JP5510186B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an electrophotographic image forming apparatus such as a copying machine, a printer, a plotter, a facsimile machine, and a printing apparatus. More specifically, the present invention relates to a toner image formed on an image bearing member on an intermediate transfer member. The present invention relates to an image forming apparatus adopting an indirect transfer system in which a toner image is transferred onto a transfer material by a secondary transfer member after the transfer.

Currently, as an image forming apparatus, there are known a monochrome mode image forming apparatus for obtaining a monochrome image and a color image forming apparatus capable of selectively obtaining both a monochrome image and a color image.
By the way, as a color image forming apparatus, a toner image of each color is formed using one photosensitive drum and a revolver type developing device, and each toner image is transferred onto a primary intermediate transfer member, and then a sheet-like recording material. There has been known a color image forming apparatus of a type that performs batch transfer onto a recording sheet.
On the other hand, due to the recent trend toward higher speed and higher functionality of color image output devices, a plurality of image forming units including image carriers and developing devices corresponding thereto are placed at positions facing the transfer belt. A so-called quadruple tandem color image forming apparatus, which is arranged side by side and sequentially transfers toner images on an image carrier onto transfer paper or a transfer belt, has become the mainstream.

  Such a quadruple tandem color image forming apparatus has the advantage that the printing speed can be increased because the toner images formed on the image carrier of each color can be transferred simultaneously. Compared to conventional one-drum intermediate transfer type color image forming apparatuses, the quadruple tandem method is disadvantageous for color misregistration between colors, and a mode for correcting image density and gradation is performed. The necessity is high. Furthermore, there is a problem that it takes about the same time as the color image forming mode regardless of the monochrome image forming mode.

  As a color image forming apparatus that can be obtained by switching between a monochrome image and a color image, for example, “Patent Document 1”, “Patent Document 2”, and FIG. A mode in which only the image forming unit is driven to obtain a monochrome image on a recording sheet, and a multi-color toner image other than a single color toner image is arranged on the upstream side of the monochrome image forming unit and is a loop-shaped intermediate transfer member A multi-color image forming unit for primary transfer sequentially to form a multi-color toner image on the intermediate transfer member, and a recording material for the multi-color toner image on the intermediate transfer member and the monochrome image of the monochrome image forming unit. There has been proposed a configuration in which a full color image is obtained by performing secondary transfer sequentially.

  Further, in “Patent Document 5”, a monochrome image forming unit directly transfers only a single color toner image to a recording material on a conveyance path to obtain a monochrome image on a recording sheet, and all the images including a single color. A four-color tandem-type second image forming unit that primarily transfers a plurality of color toner images to an intermediate transfer member and then secondarily transfers the plurality of color toner images of the intermediate transfer member to a recording material; Have been proposed in which a monochrome image and a full-color image are selectively obtained.

  Further, in the embodiment of FIG. 2 in “Patent Document 3” and “Patent Document 4”, only a monochrome toner image is directly transferred to a recording material on a conveyance path by a monochrome image forming unit, and a monochrome image is printed on a recording sheet. A first image forming unit for obtaining a toner image of a plurality of colors other than the color transferred by the first image forming unit, and a second image transfer unit for primary transfer to a loop-shaped intermediate transfer member using a revolver type developing device There has been proposed a configuration in which an image forming unit is arranged in parallel on a conveyance path so that a monochrome image and a full color image can be selectively obtained. Here, in FIG. 2 in “Patent Document 3”, the first image forming unit that obtains a single-color toner image is arranged downstream from the second image forming unit. A first image forming unit that obtains a toner image is disposed upstream of the second image forming unit.

  By the way, in the color image forming apparatus disclosed in “Patent Document 5”, in the monochrome mode, the second image forming unit and the intermediate transfer member used in the full color mode can be stopped, and the cost for monochrome image printing can be reduced. The durability of the second image forming unit, which is a full-color image unit, can be improved. However, in this case, each of the monochrome (black) image forming units for the full color mode and the monochrome mode is required, that is, two units, which increases the size of the apparatus and increases the cost.

  On the other hand, in each of the color image forming apparatuses proposed in “Patent Document 1” to “Patent Document 4”, a monochrome (black) image forming unit is provided in the image forming section for the full color mode and the image forming section for the monochrome mode. There is an advantage that can be shared. However, when each color image forming apparatus proposed in “Patent Document 1” to “Patent Document 4” is used to perform full color mode image formation, the first and second image forming units Are disadvantageous to color misregistration between colors. Further, in the monochrome image formation, there is a problem that the intermediate transfer member, the intermediate transfer member cleaning member, and the like need to operate in the same manner as the color image formation.

  The present invention has been made in view of the above circumstances, and provides an image forming apparatus that can easily achieve a plurality of image forming mode operations such as a monochrome mode, a full color mode, or an image adjustment pattern mode, and can quickly form a clear image. The purpose is to provide. Further, in the full color mode, the first intermediate transfer member that transfers all the toner images on the latent image carrier of each color including black, and in the monochrome mode, only the toner image on the black latent image carrier is transferred. By providing the second intermediate transfer member, a full color image is created by secondary transfer from the first intermediate transfer member to the recording material in the full color mode, and a second color image is transferred from the second intermediate transfer member to the recording material in the monochrome mode. The next transfer creates a monochrome image. At this time, stopping the first intermediate transfer member can improve the durability of the multi-color image forming unit. In addition, only one black image forming unit is required, which increases the cost. An object of the present invention is to provide an image forming apparatus capable of preventing the above-described problem.

  Furthermore, a toner image on the latent image carrier of each color in the full color mode and a first intermediate transfer member that transfers all of the toner images on the latent image carrier of black are transferred, and black in the monochrome mode. It is an object of the present invention to provide an image forming apparatus that can directly improve the durability and cost of a plurality of color image forming units by directly transferring a toner image on the latent image carrier to a recording material.

  In addition, in the full color mode, the first intermediate transfer body that transfers the toner images on the latent image carrier of each color to the recording material via the second intermediate transfer body, and in the black and white mode, the black latent image is transferred. It is an object of the present invention to provide an image forming apparatus capable of improving durability and preventing cost increase of a plurality of color image forming units by directly transferring a toner image on an image carrier onto a recording material.

  In order to achieve the above object, according to the first aspect of the present invention, there is provided an image forming apparatus having a plurality of latent image carriers corresponding to the respective colors, and visualized on the plurality of latent image carriers. A first state in which the toner image is secondarily transferred using a first transfer body as a recording material on a conveyance path at a secondary transfer position after the toner image is primarily transferred; and among the plurality of latent image carriers. A first intermediate transfer member that is at least switched to one latent image carrier and a second state separated from the first transfer member, and the first intermediate transfer member at a position facing the one latent image carrier. Is a second intermediate transfer body that can be switched between another transfer position and a position that is separated from the other transfer position, and the second intermediate transfer body is separated from the position where the toner image of the second intermediate transfer body is secondarily transferred to the recording material. A second transfer body that is switched to a position, a state of the first intermediate transfer body, and the first transfer body. It had a control means for changing in accordance with a position that is the primary transfer of the intermediate transfer member and the position where the secondary transfer of the second transfer body to the type of image forming modes, and it is characterized in.

In invention of Claim 2 ,
An image forming apparatus having a plurality of latent image carriers corresponding to each color, wherein a toner image visualized on the plurality of latent image carriers is primarily transferred at each primary transfer position and then the toner A first state in which an image can be secondarily transferred using a first transfer member as a recording material on a conveyance path at a secondary transfer position; and a primary transfer position of one of the plurality of latent image carriers. The first intermediate transfer is switched between a second state where the first transfer member is separated from the first transfer member and a third state where the second transfer member is brought into contact with the plurality of latent image carriers at a primary transfer position and then separated from the first transfer member. And a primary transfer feed state in which the toner image temporarily transferred from the latent image carrier prior to the primary transfer is primarily transferred to the first intermediate transfer member in the first state at the primary transfer position and the primary transfer state. A second intermediate transfer member that is switched from a transfer feed state to a released state; A second transfer body that is switched between a position at which toner images of one latent image carrier are primarily transferred to a recording material at a position different from the position of the second intermediate transfer body and a position at which the toner image is separated from the position; a control means for changing in accordance with a position at which the primary transfer of the state of the intermediate transfer member and the primary transfer feed state of the second intermediate transfer member and the second transfer body to the type of the image forming mode, the said control When the image forming mode is the full color mode, the first intermediate transfer member is switched to the first state by the first separation mechanism, and the second intermediate transfer member is switched to the primary transfer feed state by the second separation mechanism. The second separation member is switched to the disengaged position by the three separation mechanism, and in the monochrome mode, the first intermediate transfer member is switched to the second state by the first separation mechanism and the second intermediate transfer member is separated by the second separation. The second transfer body is switched to a position for primary transfer by a third separation mechanism and the first intermediate transfer body is moved to the position for primary transfer by the third separation mechanism. The second intermediate transfer member is switched to the primary transfer feed state by the second separation mechanism and the second transfer member is switched to the separation position by the third separation mechanism. Is.

According to a third aspect of the present invention, there is provided an image forming apparatus having a plurality of latent image carriers corresponding to respective colors, wherein a toner image visualized on the plurality of latent image carriers is primarily transferred. At least a first state in which the toner image is transferred to a temporary secondary transfer position and a second state in which the toner image is removed from one latent image carrier of the plurality of latent image carriers and the temporary secondary transfer position. The first intermediate transfer member to be switched, and the toner image temporarily transferred at the temporary secondary transfer position prior to the secondary transfer from the first intermediate transfer member to the secondary transfer position to transfer the recording material on the conveyance path A second intermediate transfer member that can be switched between a secondary feed transfer state in which the second transfer can be performed using the first transfer member and a state in which the secondary transfer transfer state is released, and the toner of the one latent image carrier Switching between the position where the image is primarily transferred to the recording material and the position where it is removed from the same position The second transfer body, the state of the first intermediate transfer body, the secondary transfer transfer state of the second intermediate transfer body, and the primary transfer position of the second transfer body are changed according to the type of image forming mode. And when the image forming mode is in the full color mode, the control means switches the first intermediate transfer member to the first state by the first separation mechanism and the second intermediate transfer member by the second separation mechanism. Is switched to the secondary feed transfer state, and the second transfer body is switched from the primary transfer position by the third separation mechanism to the position where it is separated. In the monochrome mode, the first intermediate transfer body is moved to the second position by the first separation mechanism. The second intermediate transfer member is switched to the disengaged state by the second separation mechanism, and the second transfer member is switched to the primary transfer position by the third separation mechanism. In the first mode, the first intermediate transfer member is switched to the first state by the first separation mechanism, the second intermediate transfer member is switched to the separation state, and the second transfer member is separated from the separation position by the third separation mechanism. It is characterized by switching to.

According to a fourth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects, the toner image is formed on the same side surface of the recording material in the full color mode and the monochrome mode. It is characterized by being transferred.

According to a fifth aspect of the present invention, in the image forming apparatus according to any one of the first to fourth aspects, the one latent image carrier is in the same position in the full color mode and in the monochrome mode. It is characterized by this.

In the invention of claim 6, wherein, in the image forming apparatus according to any one of claims 1 to 5, comprising an image detecting means provided opposite to the first intermediate transfer member, the image sensing means The image patterns transferred to the first intermediate transfer body after being visualized on all the plurality of latent image carriers are detected, and the image patterns transferred from the plurality of latent image carriers are mutually detected. The position is adjusted.

It In the present invention of claim 7, wherein, in the image forming apparatus according to any one of claims 1 to 6, wherein the first intermediate transfer member is an endless belt shape, the second intermediate transfer member is roller-shaped It is characterized by.

In the invention of claim 8, wherein, in the image forming apparatus according to any one of claims 1 to 7, wherein the first transfer body and the second transfer member is characterized in that it is roller-shaped.

According to a ninth aspect of the present invention, in the image forming apparatus according to any one of the first to eighth aspects, the latent image carrier having the shortest distance to the recording material conveyance path among the plurality of latent image carriers. The one latent image carrier.

According to a tenth aspect of the present invention, in the image forming apparatus according to any one of the first to fifth aspects, the position at which the toner image is transferred to the recording material in the monochrome mode is transferred to the recording material in the full color mode. It is characterized in that it is on the upstream side in the recording material conveyance direction with respect to the position of the recording material.

In the invention of claim 11, wherein, in the image forming apparatus according to any one of claims 1 to 10, wherein the image bearing member, a charging means, cleaning means, provided with a process cartridge which holds together the developing device It is characterized by being.

According to a twelfth aspect of the present invention, there is provided an image forming apparatus including a plurality of process cartridges according to the eleventh aspect.

According to a thirteenth aspect of the present invention, in the image forming apparatus according to the second or third aspect, the toner image is transferred to the same side surface of the recording material in the first mode and the second mode. To do.

According to a fourteenth aspect of the present invention, in the image forming apparatus according to the thirteenth aspect , the rotation direction of the first latent image carrier is the same in the first mode and the second mode. Is.

According to the present invention, when the toner images visualized on the plurality of latent image carriers are primarily transferred to the first intermediate transfer body, the full color mode and the image adjustment pattern mode can be easily achieved. When the toner image visualized on one of the latent image carriers is primarily transferred from a transfer position different from the first intermediate transfer member to the second intermediate transfer member, the monochrome mode is set. Can be easily achieved. In addition, compared with the configuration in which two image forming units for forming a black toner image are provided for the full color mode and the monochrome mode, only one black image forming unit is required, thereby reducing the cost. In particular, in the image adjustment pattern mode, the first intermediate transfer member is switched to the third state by the first separation mechanism and the second intermediate transfer member is detached by the third separation mechanism by the second separation mechanism. By switching to the position, all of the image adjustment toner adhesion patterns (image adjustment patterns) formed on the plurality of image carriers including black are transferred onto the first intermediate transfer member, and this is transferred to the first intermediate transfer member. It is possible to easily perform control for correcting the image density and gradation by detecting by the downstream image detection means in the traveling direction.

Further, according to the present invention, the second intermediate transfer member is held in the primary transfer feed state, so that the toner images visualized on the plurality of latent image carriers can be primarily transferred to the first intermediate transfer member. Therefore, the full color mode and the image adjustment pattern mode can be easily achieved, the second intermediate transfer member is held in a state of being separated from the primary transfer feeding state, and the toner image on the black latent image carrier is directly transferred to the recording material. By doing this, a monochrome image is directly transferred onto the recording material and a good monochrome image can be obtained. Therefore, it is possible to improve the durability and increase the cost of the multi-color image forming units . In particular, in the image adjustment pattern mode, the first intermediate transfer member is switched to the first state by the first separation mechanism, and the second intermediate transfer member is switched to the position where the second intermediate transfer member is separated from the primary transfer feed state by the second separation mechanism. A toner adhesion pattern (image adjustment pattern) for image adjustment formed on a plurality of image carriers including black by switching the transfer body from the primary (secondary) transfer position to the separation position by the third separation mechanism. Is transferred onto the intermediate transfer member, and this is detected by the image detecting means on the downstream side in the running direction of the intermediate transfer member, so that control for correcting the image density and gradation can be easily performed.

According to the present invention, the first intermediate transfer body on which the toner images visualized on the plurality of latent image carriers are primarily transferred transfers the toner image to the temporary secondary transfer position, and the second intermediate transfer Full-color mode is easily achieved because the toner image, which has been temporarily secondary transferred at the temporary secondary transfer position, is transferred to the secondary transfer position and secondarily transferred to the recording material on the conveyance path using the first transfer body. it can. Furthermore, since the toner image visualized on one of the plurality of latent image carriers is secondarily transferred directly to the recording material in the conveyance path using the second transfer member, the monochrome mode can be easily performed. Can be achieved. In particular, in the monochrome mode, the toner image on the black latent image carrier can be directly transferred to the recording material, and the durability of the multiple color image forming units can be prevented and the cost can be prevented. In particular, in the image adjustment pattern mode, the first intermediate transfer member is held in the first state by the first separation mechanism, and the second intermediate transfer member is switched to the position where the second intermediate transfer member is released from the secondary feed transfer state by the second separation mechanism. By switching the second transfer body from the primary transfer position by the third separation mechanism to the separation position, the image adjustment pattern mode can be easily achieved, and the image adjustment pattern mode formed on the plurality of image carriers including black is used. All the toner adhesion pattern (image adjustment pattern) is transferred onto the intermediate transfer member, which is detected by the downstream image detection means in the running direction of the intermediate transfer member, and control for correcting the image density and gradation is easy. (Claim 3).

In addition, according to the present invention, the toner image is transferred to the same surface of the recording material, and the non-image portion on the back faces the first transfer member. Therefore, even in the monochrome mode, the first transfer member is removed from the conveyance path. There is no need to retreat (Claim 4 ).

Further, according to the present invention, since one latent image carrier does not move, the exposure system can be simplified, and the movement of the latent image carrier does not adversely affect the accuracy of development and exposure (claims). Item 5 ).

Further, according to the present invention, for example, a toner adhesion pattern (image adjustment pattern) for image adjustment is formed on the carrier, for example, in a non-image area, and is primarily transferred onto the intermediate transfer member, and the running direction of the intermediate transfer member The image detecting means on the downstream side in FIG. 5 can easily perform control for correcting the misalignment of the plurality of image forming positions by comparing and aligning the image adjustment patterns. Moreover, the alignment operation here can be carried out in a manner similar to conventional four-drum tandem method (claim 6).

Further, according to the present invention, the switching configuration of the image forming unit can be simplified. (Claim 7 )
Further, according to the present invention, the first and second secondary transfer bodies can be simplified, the number of parts is reduced as compared with the case of the belt shape, the cost is reduced, and the structure can be simplified. 8 ).

Further, according to the present invention, the layout is made so that one latent image carrier is closest to the recording material conveyance path, so that the position of one latent image carrier and the members around the recording material conveyance path can be controlled by the control means. When switching, the amount of movement of the member can be reduced (claim 9 ).

Further, according to the present invention, since the transfer position of the toner image onto the recording material by the second transfer member is on the upstream side in the recording material conveyance direction, switching from full color to mono color can be performed in a relatively short time. 10 ).

  Further, according to the present invention, a plurality of latent image carriers and their image forming portions can be easily formed by a process cartridge, and the configuration of a full-color image forming apparatus can be simplified.

Further, according to the present invention, it can simplify the configuration of the image forming apparatus capable of performing full-color image formation and mono-color by a plurality of process cartridges (claim 12).

  Further, according to the present invention, the intermediate transfer member can be stopped in the first mode. For this reason, compared with the conventional tandem intermediate transfer system, the second latent image carrier and the intermediate transfer body are less likely to deteriorate, and these members can have a longer life.

Furthermore, since the toner image is transferred to the same side of the recording material regardless of the mode, the first mode and the second mode can be switched for each recording material during the output of multiple sheets. Can be output together with the image forming surface of the recording material. There is no need to invert the recording material before output in accordance with the mode switching, and an easy-to-use image forming operation can be realized with a simple configuration. (Claim 13 )
According to the present invention, since the rotation direction of the first latent image carrier is the same regardless of the mode, a common image forming process around the first latent image carrier can be used. Can be configured in a simple manner. In addition, it is not necessary to separately provide a mechanism for changing the rotation direction of the first latent image carrier or to perform separate control, and the entire apparatus can be configured simply. (Claim 14 )

1 is a cross-sectional view showing an overall configuration of a color digital multifunction peripheral as an image forming apparatus according to the present invention. FIG. 2 is an enlarged schematic side view of an image forming unit according to the first embodiment. FIG. 6 is a schematic enlarged side view of a main part of the second and third separation mechanisms of the image forming unit, where (a) shows a first state and (b) shows a second state. FIG. 2 is a schematic diagram of an image forming unit, where (a) shows a first state, (b) shows a second state, and (c) shows a third state. It is explanatory drawing of the switching mode of each part of the 1st-3rd separation mechanism performed according to each image formation mode of an image formation part. FIG. 10 is a schematic enlarged side view of a main part of each separation mechanism in first and second modifications of the image forming unit. FIG. 6 is an enlarged side view showing a switching mode of each separation mechanism in a modification of the image forming unit according to the first embodiment. It is principal part schematic side surface explanatory drawing of the image formation part in the 4th modification of 1st Embodiment. FIG. 10 is a schematic enlarged side view illustrating a switching mode in a full color mode of an image forming unit according to a second embodiment. FIG. 5 is a schematic side view of an image forming unit according to a second embodiment, in which (a) shows a switching mode in a monochrome mode, and (b) shows an image adjustment time. FIG. 10 is a schematic side view of an image forming unit according to a third embodiment, showing a switching mode in the full color mode in (a) and a switching mode in the monochrome mode in (b). It is a schematic side view of the image formation part concerning 3rd Embodiment, and shows the switching mode at the time of image adjustment. FIG. 10 is a schematic side view of an image forming unit according to a fourth embodiment, in which (a) shows a switching mode in a full color mode and (b) shows a switching mode in a monochrome mode. It is a schematic side view of the image formation part concerning 4th Embodiment, and shows the switching aspect at the time of image adjustment. FIG. 10 is a schematic side view of an image forming unit according to a fifth embodiment, in which (a) shows a switching mode in a full color mode and (b) shows a switching mode in a monochrome mode. It is a schematic side view of the image formation part concerning 5th Embodiment, and shows the switching aspect at the time of image adjustment. FIG. 10 is a schematic side view of an image forming unit according to a sixth embodiment, showing a switching mode in the full color mode in (a) and a switching mode in the monochrome mode in (b). It is a schematic side view of the image formation part concerning 6th Embodiment, and shows the switching mode at the time of image adjustment. FIG. 4 is an explanatory diagram of mode switching characteristics of an image forming unit used in the image forming apparatus according to the present invention, in which (a) shows a switching mode related to claims 1 to 3, (b) shows a switching mode related to claims 4 to 6; c) describes the switching modes according to claims 7 to 9, respectively. It is arrangement | positioning and functional characteristic explanatory drawing of each structural member of the image forming part concerning 1st-6th embodiment.

  FIG. 1 shows a schematic configuration of a color digital multifunction machine as an image forming apparatus employing an embodiment of the present invention. The color digital multifunction peripheral (image forming apparatus) 1 includes an image forming unit 100 that forms an image corresponding to gradation data of each color, and a paper feeding unit 200 that conveys a recording sheet P that is a recording medium. The paper discharge unit 300 is provided at the downstream end of the conveyance path R extending from the paper supply unit 200. Further, an image processing apparatus (IPS) 400 that performs predetermined image processing on image data received from a personal computer (not shown), a facsimile, or the scanner unit 98 at the top of the image forming unit 100, the image processing apparatus 400 and the image forming apparatus. A control unit 500 that controls the unit 100 and the paper feeding unit 200 is provided.

In this color digital multi-function peripheral 1, color image information transmitted from a document read by the scanner unit 98 or the like is separated into colors of yellow, cyan, magenta, and black by an image processing apparatus (IPS) 400, and a plate of each color is obtained. Are sent to an exposure device (optical unit) 8 of the image forming unit for each color.
Here, the image forming unit 100 of the color digital multi-function peripheral 1 detachably displaces the image forming units 60Y (yellow), 60C (cyan), 60M (magenta), and 60B (black) for four colors at predetermined positions. To support. The intermediate transfer unit 10 is above the image forming units for the four colors, and the exposure device (optical unit) 8 is capable of irradiating laser light in accordance with the plate data of each color from the image processing apparatus (IPS) 400 on the lower side. Deploy oppositely. The optical unit 8 is not limited to the laser system, and may be an LED system.

A paper feeding unit 26 on the paper feeding unit 200 side is disposed below the optical unit 8, and a conveyance path R extending from the paper feeding unit 26 is first and second (upstream and downstream) on the side of the intermediate transfer unit 10. After passing through the secondary transfer positions 57f and 57r, the paper passes through the fixing unit 6 and reaches the paper discharge tray 17 of the paper discharge unit 300.
Next, the image forming unit 100 constituting the main part of the first embodiment of the present invention will be described.

  As shown in FIG. 1, the image forming unit 100 includes four color image forming units 60Y (yellow), 60C (cyan), 60M (magenta), and 60B (black) at the center of the apparatus main body 99. A first intermediate transfer belt (hereinafter simply referred to as an intermediate transfer belt) 11 that is a first intermediate transfer member of the intermediate transfer unit 10 is provided on the upper side. The intermediate transfer belt 11 rotates in a counterclockwise direction in FIG. 1, and an image forming unit 60 for four colors is arranged in series along the belt moving direction A1 in the lower part thereof (subscripts are omitted in the description of the four-color common member). The tandem system is arranged.

  The intermediate transfer unit 10 includes an intermediate transfer belt 11 that is a first intermediate transfer member, three suspension rollers 72, 33, and 74 that rotatably support the intermediate transfer belt 11 in a loop shape, and each photosensitive drum. 20 includes a primary transfer roller 12 that transfers the toner image formed on the intermediate transfer belt 11 to the intermediate transfer belt 11, and a secondary transfer roller 66 that further transfers the toner image transferred onto the intermediate transfer belt 11 to the recording paper P. .

  A support bracket 230 (see a two-dot chain line in FIG. 2) supported by the apparatus main body 99 is provided in a region facing the intermediate transfer belt 11 on the rear side in FIG. 1, and three suspension rollers 72, 33, 74 are provided here. The intermediate transfer belt 11 suspended on the photosensitive drum 20 faces the photosensitive drums 20 of the four color image forming units 60Y (yellow), 60C (cyan), 60M (magenta), and 60B (black) through primary transfer positions. The primary transfer roller 12 is pivotally supported. Incidentally, the primary transfer roller 12B of 60B (black) is provided so as to be switched and moved as will be described later.

In FIG. 1, an arrow A1 indicates the moving direction of the intermediate transfer belt 11, and an arrow B1 indicates the rotating direction of the photosensitive drum 20.
The paper feed unit 26 shown in FIG. 1 includes a paper feed roller 24 that feeds the recording paper P from the paper feed cassette 25 or the manual paper feed tray 27, and the fed recording paper P at two locations, upstream and downstream. A registration roller pair 4 and the like are sequentially provided to the first and second secondary transfer positions 57f and 57r in a timely manner.
Reference numeral 51 denotes a duplex unit. During double-sided printing, the recording paper P is switched back by the paper discharge roller pair 7, transported to the transport path R 2 of the duplex unit by the switching claw 22, and transported toward the registration roller pair 4 by the transport roller pair 23. Reference numeral 28 denotes a paper feed roller for manual paper feed, and 29 denotes a pair of transport rollers.
The fixing unit 6 includes a heating roller 62, a fixing roller 65, a fixing belt 64, and a pressure roller 63, and performs fixing by applying heat and pressure to the toner image on the recording paper P.

In the above configuration, as shown in FIGS. 1 and 2, first, the photosensitive drum 20Y of the first color yellow image carrier unit 60Y is uniformly charged by the charging device 79Y, and then the optical unit 8 irradiates the exposure position. A latent image is formed by the laser beam that has been developed, and this is developed by the developing device 80Y to form a toner image.
The toner image formed on the photosensitive drum 20Y is primarily transferred onto the intermediate transfer belt 11 by the action of the primary transfer roller 12Y. The photosensitive drum 20Y after the primary transfer is cleaned by the cleaning device 71Y to prepare for the next image formation.

The residual toner collected by the cleaning device 71 is stored in a waste toner collection bottle (not shown) installed in the direction of taking out the image carrier unit (the direction of the rotation axis of the photosensitive drum). It is detachable from the main body of the image forming apparatus so that it can be replaced when the waste toner collecting bottle is full.
A similar full color mode image forming process is performed in each of the C, M, and B image carrier units 60C, 60M, and 60B to form toner images of each color, and sequentially superimposing the previously formed toner images. Is transcribed.

  Under the image forming unit 100, paper feed trays 25 and 25 having different recording paper sizes are provided, and the recording paper P fed from each paper feed tray by the paper feed unit 24 is fed by a transport unit (not shown). It is conveyed and reaches the registration roller pair 4, where the skew is corrected and the registration roller pair 4 passes through the front secondary transfer position 57 f or here at a predetermined timing to pass through the suspension roller 72 at the rear secondary transfer position 57 r. Then, it is conveyed to a rear secondary transfer roller (first transfer body) 66. Here, in the monochrome mode, secondary transfer is performed at the front secondary transfer position 57f between the intermediate transfer roller 200, which is the second intermediate transfer body, and the front secondary transfer roller (second transfer body) 204. It passes through the secondary transfer position 57r as it is (without transfer process).

  In the full color mode, the recording paper P passes through the upstream secondary transfer position 57f as it is (no transfer process), and then is the secondary transfer that is the first transfer body disposed opposite to the downstream secondary transfer position 57r. The toner image formed on the intermediate transfer belt 11 by the action of the roller 66 is secondarily transferred to the recording paper P. The recording paper P on which the toner image is secondarily transferred is conveyed to the fixing unit 6. The recording paper P onto which the toner image has been transferred is fixed at the nip portion between the fixing roller 65 of the fixing unit 6 and the pressure roller 63 to form a color image. After the fixing, the recording paper P is transported along the transport path R, and is discharged and stacked on the paper discharge tray 17 by the paper discharge roller pair 7 in a face-down state. In the duplex mode, the switching claw 22 guides to the transport path R2, reverses by the duplex unit 51, and then transports to the registration roller pair 4 to follow the same path as the single-sided copy.

  The intermediate transfer belt 11 after the secondary transfer is cleaned by a belt cleaning device 13 (see FIG. 1) having a cleaning blade 76 in a case 77. In this embodiment, a blade type is used, but the present invention is not limited to this, and a fur brush roller or a magnetic brush cleaning system may be used.

  As described above, the image detection unit 210 is disposed opposite to the upstream side of the cleaning blade 76 and the downstream side of the secondary transfer position 57r and the portion facing the suspension roller 74. Here, in the image adjustment pattern mode, the control unit 500 drives the image forming unit 100 to form a toner adhesion pattern (image adjustment pattern) (not shown) for image adjustment in a non-image area on the image carrier 20. Then, the image detection means 210 disposed on the downstream side of the upward surface of the intermediate transfer belt 11 causes an image adjustment pattern, that is, a density gradation based on a set alignment line pattern or density adjustment line or dot. A pattern is detected so that control such as correction of a deviation of an image forming position can be easily performed.

To supply new toner to each of the image carrier units 60Y, 60C, 60M, and 60B provided on the intermediate transfer belt 11, toner bottles 9Y, 9C, 9M, and 9K are provided on the upper portion of the apparatus main body 99. These are rotated, and the toner is conveyed to each developing device 80 through a pipe.
In the above description, the intermediate transfer belt 11 is a single-layer or multi-layer belt. In the case of a single layer, it is made to a thickness of 60 to 150 μm using polyvinylidene fluoride (PVdF), polyamideimide body (PA), polyimide body (PI), ETFE or the like. These require mechanical strength. Electrical characteristics are adjusted to 109 to 1012 Ω · cm by blending carbon black. The production is made by centrifugal molding or dipping.

In the case of a multilayer, an elastic layer and a surface layer are molded on the above-mentioned substrate. The elastic layer is formed by kneading into a flame retardant rubber such as carbon black. The rubber material is made of chloroprene rubber or the like in the same resistance region as the base in consideration of flame retardancy. Specifically, a molding method in which the substrate is cooled to some extent after molding of the substrate and then subjected to a treatment such as primer on the surface, then is made by roller coating or dipping, and vulcanized there is appropriately employed.
Finally, the surface layer is molded to a thickness of 0.5 to 10 μm with a material that does not have strong adhesion to the toner. Various materials such as urethane, PC, fluorine resin, and silicon resin can be considered as the material of the surface layer. Although this layer is thin and about 1 μm, high voltage is applied, so that the layer is made of a sufficiently high resistance material so as not to cause partial discharge, and is manufactured by spray coding or dipping.

  As shown in FIG. 2, the above-described intermediate transfer belt 11 is looped around a suspension roller 72, 33, 74 or the like so as to be rotatable. Supported. Here, the suspension roller 72, which is a part of the stretching portion that supports the intermediate transfer belt 11, is disposed opposite to the rear secondary transfer position 57 r on the conveyance path R. Further, a rear secondary transfer roller 66 as a first transfer member is disposed opposite to the suspension roller 72 with the rear secondary transfer position 57r interposed therebetween. Thereafter, at the secondary transfer position 57r, the rear secondary transfer roller 66 can press the recording paper P toward the suspension roller 72 and the intermediate transfer belt 11 to form a transfer nip, and the suspension roller 72 has a bias 81 ( 3 (a)) is applied. The suspension roller 72 is a transfer-facing roller, and is molded with a thin solid rubber material as a core bar to reliably press and convey the recording paper P and the intermediate transfer belt 11. The resistance is preferably in the same resistance region as the secondary transfer roller 66.

  By applying a bias to each of the upstream and downstream secondary transfer rollers 204 or 66 (here, only shown on the downstream side in FIG. 3), the primary transfer is performed on the intermediate transfer belt 11 or the intermediate transfer roller 200. The transfer performance at the time of secondary transfer of the superimposed toner images to the recording paper P, that is, transfer efficiency and transfer accuracy can be improved. That is, here, the secondary transfer roller 66 or 204 is applied by applying a bias having a polarity opposite to that of the toner to attract the toner to the recording paper P side (transfer by attractive force), or the intermediate transfer belt 11 is supported. Transfer (transfer by repulsive force) may be performed by applying a bias having the same polarity as the toner to the suspension roller 72 or the intermediate transfer roller 200 and pushing the toner from the intermediate transfer belt 11 or the intermediate transfer roller 200 to the recording paper P side. Further, if the roller facing the roller to which the bias is applied is electrically grounded, the transfer performance can be improved more reliably.

The post-secondary transfer roller 66 is molded into a shaft by blending an ionic conductive agent (lithium ion or sodium ion), carbon black, or the like with urethane, EPDM, or the like. The surface hardness is adjusted to 15 to 70 degrees asuka C, and the surface layer is further coated with another resin material (such as Teflon (registered trademark)) to eliminate the influence of long-term toner filming and the like.
Further, the other suspension roller 33 that suspends the intermediate transfer belt 11 and the suspension roller 74 that is a drive roller have no application to apply an electric field, and may be floated or grounded. Further, a metal roller or a resin roller may be used. The rotating shaft 741 of the suspension roller 74 as a driving roller is pivotally supported by the apparatus main body 99 via a support bracket 230 (see FIG. 2), receives a rotational force from a driving source (not shown), and causes the intermediate transfer belt 11 to loop. To turn.

  As described above, the rear secondary transfer roller (first transfer body) 66 facing the suspension roller 72 at the rear secondary transfer position 57r and the front secondary transfer facing the intermediate transfer roller 200 at the front secondary transfer position 57f. The roller (second transfer member) 204 has a roller shape. With such a configuration, the image forming unit 100 here performs color matching and density adjustment detection processing in the full color mode and the image adjustment pattern mode on the intermediate transfer belt 11 side. For this reason, the rear secondary transfer roller 66 and the front secondary transfer roller 204 may have a relatively simple roller shape, and the cost can be reduced.

  By the way, as shown in FIGS. 1 and 2, each of the photosensitive drums 20 of the image forming units 60Y (yellow), 60C (cyan), 60M (magenta), and 60B (black) for four colors is A charging device 79, an exposure position from the optical unit 8, a developing device 80, a primary transfer position facing the primary transfer roller 12, and a process cartridge integrally assembled and held with a cleaning device 71 are formed. The configuration of the unit 60 (subscripts are omitted in the description of the four-color common member) can be simplified. In addition, since the image forming units 60 (process cartridges) for four colors are provided, the configuration of the image forming unit 100 that can form full-color and mono-color images can be simplified.

Next, as shown in FIGS. 1 and 3B, the black B image forming unit 60B is disposed on the downstream side in the traveling direction on the downward surface side of the intermediate transfer belt 11 as the first intermediate transfer member. The latent image carrier 20 </ b> B here is a primary transfer position Pf <b> 1 that faces the upper intermediate transfer belt 11.
In addition, a second primary transfer position Pf2 different from that is provided, and a roller-shaped intermediate transfer roller 200 as a second intermediate transfer body is disposed opposite thereto. That is, the black (single color) photosensitive drum 20B can primarily transfer the toner image to the intermediate transfer belt 11 from the primary transfer position Pf1, or can primarily transfer to the intermediate transfer roller 200 from another primary transfer position Pf2. The black image forming unit 60B (black) (one latent image carrier) can be used in both the full color mode and the monochrome mode.

By the way, as shown in FIGS. 1 and 3A, the photosensitive drum 20B of the black image forming unit 60B (black) is formed to have a relatively larger outer diameter than the other three photosensitive drums 20. A relatively large outer peripheral area is secured, thereby facilitating securing the arrangement positions of the plurality of transfer means (two primary transfer positions Pf1, Pf2). In particular, the photosensitive drum 20B has a position Pf2 on the outer periphery which is shifted from the primary transfer position Pf1 by about 90 degrees in the circumferential direction in addition to the primary transfer position Pf1 opposed to the primary transfer roller 12B. On the other hand, the intermediate transfer roller 200 which is the second intermediate transfer member is opposed to and is held so as to be able to contact and separate at a primary transfer position P31 (the position shown in FIGS. 3A and 3B). As shown in FIG. 3B, a front secondary transfer roller 204, which is a second transfer body, is disposed on the opposite side of the primary position Pf2 of the intermediate transfer roller 200 from the front secondary transfer position 57f. .
In some cases, the arrangement interval of the photosensitive drums 20 is relatively large, the outer diameter of the photosensitive drums 20 is set to be relatively large, and the black photosensitive drum 20B and the photosensitive drums 20 of other colors are arranged. The configuration may be simplified by forming the outer diameter the same.

Next, a switching mechanism when the image carrier unit 60B for black B is driven in each image forming process in the full color mode and the monochrome mode will be described with reference to FIGS.
In order to support the intermediate transfer belt 11 in a stretched state, a support bracket 230 (indicated by a two-dot chain line in FIG. 2) integral with the apparatus main body 99 is provided with a downstream rear secondary transfer position 57r and a black B primary transfer position. A first separation mechanism 201 that switches Pf1 is attached. Further, the intermediate transfer roller 200, which is the second intermediate transfer body, in the second primary transfer position Pf2, the second separation mechanism 202 that switches the position P31 to which the toner image is primarily transferred from the photosensitive drum 20B for black B, and the upstream A third separation mechanism 203 that switches and operates the front secondary transfer roller 204 as a second transfer body that contacts and separates from the intermediate transfer roller 200 across the front secondary transfer position 57f is provided in the apparatus main body 99 in the second base frame 240. It is attached through.
As shown in FIG. 2, the first separation mechanism 201 includes a bending lever 220 that switches the suspension roller 72, and a bending lever 223 that switches the suspension roller 33 and the primary transfer roller 12B.

  In FIG. 2, the upper bending lever 220 is pivotally supported at the center by a support bracket 230, a suspension roller 72 is pivotally supported at the swinging end, and the other swinging end is used for switching. A cam 222 that is rotated by approximately 180 ° by the source 251 contacts. The bending lever 220 abuts on the cam 222 by the elastic force of the spring 221. Here, when the cam 222 is at the retracted position b, the suspension roller 72 is held at the drive position P11 (see FIG. 3A) facing the downstream secondary transfer position 57r. When the cam 222 is switched to the pressing position d (see the two-dot chain line in FIG. 2), the suspension roller 72 is detached from the secondary transfer position 57r and held at the separation position P12.

  In FIG. 2, the lower bending lever 223 is pivotally supported at the center by the support bracket 230, and the primary transfer roller 12B facing the photosensitive drum 20B and the suspension roller 33 at the suspension are pivotally supported by the swinging piece. ing. The other short piece of the bending lever 223 comes into contact with a cam 224 that is switched by about 180 ° by an appropriate rotation drive source 252. When the cam 224 is at the retracted position b, the primary transfer roller 12B is held at the primary transfer position Pf1, and the suspension roller 33 is held at the drive position P21.

When the cam 224 is switched to the pressing position d, the primary transfer roller 12 facing the photosensitive drum 20B is separated from the primary transfer position Pf1, and the suspension roller 33 is held at the separation position p22.
Here, as shown in FIG. 2, the suspension roller 72 is switched to the drive position P11, and the suspension roller 33 and the primary transfer roller 12B are switched to the drive position P21 together, so that the first state (first suspension state) m1 (FIG. 4). (See (a)) is held. Further, the second state (second state) m2 (see FIG. 4B) is maintained by switching the suspension roller 72 to the separation position P12 and the suspension roller 33 and the primary transfer roller 12B to the separation position P22. . Further, the suspension roller 72 is switched to the separation position P12 and the suspension roller 33 and the primary transfer roller 12B hold the drive position P21, whereby the third state (third suspension state) m3 (see FIG. 4A) is maintained. The Further, when the primary transfer roller 12B is separated from the primary transfer position Pf1, or when the suspension roller 72, the suspension roller 33, and the primary transfer roller 12B are sequentially switched, the state of the intermediate transfer belt 11 is loosened. The switching positions of the rollers 72, 33, and 12B are set in advance so that excessive tension is not applied.
As shown in FIG. 2, the first separation mechanism 201 alternately switches the suspension roller 72 and the suspension roller 33 to the drive positions P11 and P21 and the separation positions P12 and P22. This is performed by the control unit 500 for switching the operation.

  As shown in FIGS. 3A and 3B, the second separation mechanism 202 includes an L-shaped lever 226 that switches the intermediate transfer roller 200 as the second intermediate transfer member. The L-shaped lever 226 has a bent portion pivotally supported by the second base frame 240 on the apparatus main body 99 side, the intermediate transfer roller 200 pivotally supported at the tip of one extension portion, and the vicinity of the end portion of the other extension portion. The cam 231 contacts the lower surface. The other end of the compression spring 227 whose one end is supported by the locking piece 241 of the support bracket 240 abuts on the upper surface in the vicinity of the end of the other extension portion so as to apply a pressing force. As a result, the primary transfer position Pf2 facing the black B photosensitive drum 20B and the primary transfer position Pf2 different from the intermediate transfer belt 11 is transferred from the primary transfer position P31 and the primary transfer position P31. The intermediate transfer roller 200 is supported so as to be switchable to a separation position P32 that is a separation position.

When the cam 231 is switched to the pressing position d by the rotation driving source 253, the intermediate transfer roller 200 facing the second primary transfer position Pf2 of the photosensitive drum 20B is held at the transfer position which is the position P31 where the primary transfer is performed. . When the cam 231 is switched to the retracted position b, the intermediate transfer roller 204 is detached from the primary transfer position facing the photosensitive drum 20B and is switched to the separation position P32.
The second separation mechanism 202 switches the intermediate transfer roller 200 between the transfer position P31 (primary transfer position) and the separation position p32 as appropriate. The switching control is performed by the control unit 500 via the rotation drive source 253.

As shown in FIGS. 3A and 3B, the third separation mechanism 203 includes an L-shaped lever 229 that switches the front secondary transfer roller 204 as the second transfer body. The L-shaped lever 229 is pivotally supported at the center of the second base frame 240 on the apparatus main body 99 side, the front secondary transfer roller 204 is pivotally supported at the tip of one extension, and the end of the other extension A cam 236 contacts the upper surface. The other end of the compression spring 232, one end of which is supported by the locking piece 242 of the second base frame 240, is in contact with the lower surface of the end of the other extending portion so as to apply a pressing force. As a result, the front secondary transfer roller 204 can be held at the transfer position u1 which is the secondary transfer position 57f with respect to the intermediate transfer roller 200 at the front secondary transfer position 57f, or can be withdrawn via the separation distance D2. It can be held at u2.
When the cam 236 is switched to the pressing position d by the rotational drive source 254, as shown in FIG. 3B, the front secondary transfer roller 204 is brought into contact with the intermediate transfer roller 200 at the transfer position P31 to transfer the position u1 (second). When the cam 236 is switched to the retracted position b, the front secondary transfer roller 204 is further moved away from the intermediate transfer roller 200 at the separation position p32 as shown in FIG. 3A. Can be switched to

As described above, the separation distance D1 between the photosensitive drum 20B and the intermediate transfer roller 204 switched by the second separation mechanism 202, and the separation distance D2 between the intermediate transfer roller 204 and the front secondary transfer roller 204 switched by the third separation mechanism 203. The distance may be sufficient to prevent toner scattering from the photosensitive drum 20B and contact between the members. However, in consideration of the stability of conveyance of the recording paper P, it is better to reduce the fluctuation of the recording material conveyance path in the full color mode and the monochrome mode shown in FIGS. 3A and 3B, and these distances are small. Better. For example, the diameter of the photosensitive drum 20B may be 40 millimeters and the diameter of the intermediate transfer roller 200 may be 20 millimeters. For example, the distances D1 and D2 may be about 1 millimeter to 20 millimeters, respectively.
In this manner, the first to third separation mechanisms 201, 202, and 203 (see FIG. 3A) are stretched around the suspension rollers 72, 33, and 74 to run and rotate in a loop shape. The intermediate transfer belt 11 is switched to the first to third states m1 to m3 and the secondary transfer at the secondary transfer positions 57f and 57r before and after the conveyance path R is selectively performed, and these image formation controls are performed. Is performed by the control unit 500.

  The transfer roller 200 that switches between the transfer position P31 and the separation position p32 has been described above. In the image forming unit 100, on the intermediate transfer belt 11 side, color registration and density adjustment detection processing is performed in the full color mode and the image adjustment pattern mode. For this reason, the transfer roller 200 (second intermediate transfer member) only needs to transfer the toner image on the latent image carrier 20B to the recording paper in the monochrome mode, and may have a roller shape. As a result, the number of parts is smaller than in the case of the belt shape, and the cost is reduced.

  In some cases, a belt-shaped second intermediate transfer member may be used instead of the roller-shaped transfer roller 200 (second intermediate transfer member).

Next, the control function by the control unit 500 of the image forming unit 100 constituting the main part of the first embodiment of the present invention and the operation of each unit will be described.
When using the image forming apparatus, the user gives an instruction using an operation panel on the image forming apparatus (not shown) or an image forming mode on a personal computer connected to the network. Alternatively, a determination unit (not shown) automatically determines a color included in the output image, and selects an image forming mode according to the toner color to be used. Upon receiving these instructions or instructions, the control unit 500 switches the image forming mode.

  At this time, image data is received from a personal computer (not shown) or a scanner unit 98, which is subjected to predetermined image processing by an image processing apparatus (IPS) 400, and laser light is blackened from the optical unit 8 in accordance with the obtained data. The photosensitive drum 20B of the image forming unit 60B (black) is irradiated and exposed to form a black toner image. In the monochrome mode, optical writing is not performed on the photosensitive drums 20 of the plurality of image forming units 60Y, 60C, and 60M, and toner images are not transferred.

  In this monochrome mode, the controller 500 stops the intermediate transfer belt 11 and the image forming units 60Y, 60C, and 60M, the suspension roller 72 is at the separation position P12, the suspension roller 33 is at the separation position P22, and the primary transfer roller 12B is primary. The first separation mechanism 201 is switched so that the intermediate transfer belt 11 is stretched in the second state m2 (see FIG. 4B) by switching to a position (see FIG. 3B) that is separated from the transfer position Pf1. Here, by switching the suspension roller 72 to the separation position P12, the intermediate transfer belt 11 slides on the toner image surface of the transfer paper that has been transferred at the upstream secondary transfer position 57f at the downstream secondary transfer position 57r. This prevents the toner image from being stained.

Further, the front secondary transfer roller 204 is brought into contact with the intermediate transfer roller 200 at a transfer position which is a position P31 where the intermediate transfer roller 200 is primarily transferred with respect to the photosensitive drum 20B of the black image forming unit 60B (black). The second and third separation mechanisms 202 and 203 are driven so as to switch to the transfer position u1 (secondary transfer position). The switching pattern in the monochrome mode is shown in FIG. 5, and the schematic layout of the intermediate transfer belt 11 is shown by reference numeral (m2) in FIG.
In this monochrome mode, the toner image primarily transferred from the black photosensitive drum 20B to the intermediate transfer roller 200 at the second primary transfer position Pf2 is transferred to the intermediate transfer roller 200 at the front secondary transfer roller 204 at the transfer position u1. Is secondarily transferred to the recording paper P in the transport path R. The recording paper P onto which the toner image has been secondarily transferred reaches the secondary transfer position 57r downstream from the upstream secondary transfer position 57f, but the intermediate transfer belt 11 here has moved to the separation position P12 side, The four-layered toner images that have been secondarily transferred are conveyed to the fixing unit 6 without being stained, fixed, and discharged to the paper discharge unit 300.

Here, since the black photosensitive drum 20B is laid out so as to be closest to the conveyance path (recording material conveyance path) R, the position of the intermediate transfer roller 200 which is a member around the latent image carrier and the recording material conveyance path. Is switched by the control means, the separation distance D1 (movement amount) of the intermediate transfer roller 200 can be relatively reduced, and the apparatus can be made compact.
In the monochrome mode, the intermediate transfer belt 11 and the plurality of image forming units 60Y, 60C, and 60M do not rotate and are merely opposed to the stretched surface. The photosensitive drums 20 of the image forming units 60Y, 60C, and 60M may be idled.
In this case, there is no transfer of the toner image, and only the photosensitive drum 20B carrying the black toner image is in contact with the tension surface of the intermediate transfer belt 11, and the intermediate transfer facing the second primary transfer position Pf2. The black toner image is secondarily transferred onto the recording paper P in association with the primary transfer to the roller 200 and further with the front secondary transfer roller 204. In particular, since the toner image is transferred onto the same side surface of the recording paper P in the full color mode and the monochrome mode, the non-image portion on the back faces the rear secondary transfer roller (first transfer body) 66. Therefore, it is not necessary to retract the rear secondary transfer roller 66 from the conveyance path R even in the monochrome mode.

As described above, the plurality of image forming units 60Y, 60C, and 60M are in contact with the stretched surface of the intermediate transfer belt 11 in the monochrome mode, but may be separated in some cases. (Refer to the switching pattern in FIG. 5)
For example, you may comprise so that it may mention later as the modification 1 of 1st Embodiment. That is, as shown in FIG. 7, the entire intermediate transfer belt 11 is supported on the movable base frame 530, and is switched up and down with respect to the plurality of image forming units 60Y, 60C, 60M, 60B arranged opposite to each other, and is driven by a solid line. You may comprise so that it may switch to the position n1 and the evacuation position n2 of a two-point difference line. This configuration will be described in detail in the description of Modification 1 of the first embodiment to be described later.

Next, the control unit 500 receives an instruction to switch the image forming mode to the full color mode, receives the image data, performs predetermined image processing, and the laser light from the optical unit 8 has four colors according to the obtained data. The photosensitive drums 20B of the image forming units 60Y, 60C, 60M, and 60B are exposed to form four-color toner images. In the full color mode, the image forming units 60Y, 60C, 60M, and 60B of the image forming units 60Y, 60C, and 60B of all four colors are in contact with the stretched surface of the intermediate transfer belt 11 on substantially the same plane. The structure of the portion 100 can be simplified and the printing speed can be increased.
Here, by switching the first separation mechanism 201, the controller 500 switches the suspension roller 72 to the drive position P11 facing the downstream secondary transfer position 57r, the suspension roller 33 to the drive position P21, and the primary transfer roller 12 to the primary transfer. The intermediate transfer belt 11 is switched to and held in the first state m1 (see FIGS. 4A and 3A). The switching pattern in the full color mode is shown in FIG. 5, and the schematic layout of the intermediate transfer belt 11 is shown by reference numeral (m1) in FIG.

Further, by performing secondary transfer at the secondary transfer position 57r between the rear secondary transfer roller (first transfer body) 66 and the suspension roller 72, the intermediate transfer roller 200 at the secondary transfer position 57f on the upstream side is moved. The second and third separation mechanisms 202 and 203 are switched to the separation position p32 so as to hold the front secondary transfer roller 204 at the separation position u2 (see FIG. 5). It passes through the next transfer position 57f as it is (without processing). Here, the secondary transfer roller 66 after the secondary transfer position 57r and the front secondary transfer roller 204 at the upstream secondary transfer position 57f are both rollers. As a result, the second secondary transfer body can be simplified, the number of parts is reduced as compared with the belt shape, the cost is reduced, and a simple configuration can be achieved.
In this full color mode, the recording paper P that has passed through the secondary transfer position 57f on the upstream side of the transport path R as it is is primarily transferred to the intermediate transfer belt 11 at the secondary transfer position 57r on the downstream side. Are secondarily transferred, conveyed to the fixing unit 6, fixed, and discharged to the paper discharge unit 300.

  Next, when the control unit 500 receives a command to switch the image forming mode to the image adjustment pattern mode, the control unit 500 uses a laser beam from the optical unit 8 to set a preset line pattern or density adjustment for alignment. A latent image is written and formed on each non-image area on the photosensitive drum 20B of each of the image forming units 60Y, 60C, 60M, and 60B in accordance with the image signal of the density gradation pattern by the lines or dots for use on the intermediate transfer belt 11. Primary transfer.

  At this time, as shown in FIG. 2, the controller 500 switches the first separation mechanism 201 to move the suspension roller 72 to the separation position P12 indicated by a two-dotted line, the suspension roller 33 to the driving position p21, and the primary transfer roller 12 to the driving position p21. Is held at the primary transfer position Pf1, and the intermediate transfer belt 11 is stretched in the switched state and held in the third suspended state m3 (see FIG. 4C). Further, the intermediate transfer roller 200 is switched to the separation position P32 (see FIG. 3A) and the front secondary transfer roller 204 is switched to the separation position u2 with respect to the photosensitive drum 20B of the black image forming unit 60B (black). The second and third separation mechanisms 202 and 203 are driven (see FIG. 5). A schematic layout of the intermediate transfer belt 11 in this image adjustment pattern mode is indicated by a symbol (m3) in FIG.

  In the image adjustment pattern mode, the supply of the recording paper P is stopped, and the latent image is transferred onto the intermediate transfer belt 11 in accordance with an image signal of a four-color image adjustment pattern or a density gradation pattern by density adjustment lines or dots. An image is formed, and a toner image of each color is formed by each developing device. Further, each toner image is formed on the intermediate transfer belt 11 by primary transfer. Further, after receiving the primary transfer of each color toner image by the primary transfer means, it passes through the downstream secondary transfer position 57r and approaches the suspension roller 74 (drive roller).

Here, as shown in FIGS. 1, 2, and 4 (c), the image detection unit 210 is disposed opposite to the suspension roller 74 (drive roller). Here, the four color image adjustment patterns are read by the image detection means (optical detection sensor) 210 provided at a position facing the suspension roller 74, whereby positional deviation information, density and gradation of each color of BMCY are read. Information is obtained. The optical detection sensor 210 is provided at a position facing the suspension roller (driven roller) 74. The position information read by the optical detection sensor 210 is used to adjust the sub-scanning direction start timing of the light writing of each color to make the color misalignment inconspicuous, the density information is used for process control, and the image density / color tone Optimization will be performed.
The toner pattern after reading is transported on the intermediate transfer belt 11, collected by the intermediate transfer cleaning device 13, and accommodated in a waste toner bottle by a waste toner transport path (not shown). In FIG. 1, FIG. 2, and FIG. 4C, the image detection means (optical detection sensor) 210 detects at a position on the suspension roller 74 (drive roller). Detection may be performed anywhere after the black is first transferred to the cleaning unit 13, or may be detected on the tension roller 33 or the intermediate transfer belt 11.

  As described above, in the image adjustment pattern mode, all the toner images of the four color image adjustment patterns are primarily transferred onto the intermediate transfer belt 11 (first intermediate transfer member), and the positional deviation of each color of YCM and B is performed. Information and density information are obtained, and image adjustment and alignment used in the full color mode can be performed on the first intermediate transfer member. For this reason, it is not necessary to detect color matching on the secondary transfer body as in the case of a conventional apparatus that employs a direct transfer of black and a tandem configuration other than black, and more accurate positional shift and density control can be performed. In addition, in the conventional apparatus, it is necessary to transfer black and color onto the same secondary transfer body, and the secondary transfer body becomes large. In addition, the surface material of the secondary transfer member needs to be smooth.

As described above, in the image forming apparatus according to the first embodiment, when the toner image is primarily transferred to the intermediate transfer belt 11 (first intermediate transfer member), the full color mode and the image adjustment pattern mode can be easily achieved. The toner image visualized on the black photoreceptor 20B, which is one of the plurality of latent image carriers, is transferred from the transfer position Pf2 different from the intermediate transfer belt 11 to the intermediate transfer roller (second When primary transfer is performed to the intermediate transfer body 200, the monochrome mode can be easily achieved. Here, since only one black B image forming unit 60B is required, the cost is reduced.
Further, in the full color mode, the intermediate transfer belt 11 is switched to the first state m1 by the first separation mechanism 201, and a good full color image can be obtained as in the case of the normal quadruple tandem.

  In the monochrome mode, the intermediate transfer roller (second intermediate transfer member) 200 is secondarily transferred by the second separation mechanism 202 to the position P31 where the secondary transfer roller 204 (second transfer member) is secondarily transferred by the third separation mechanism 203. By switching to the transfer position u1, the toner image in the monochrome mode is secondarily transferred to the recording paper P, and a good monochrome image is obtained.

  In particular, in the monochrome mode, a plurality of photoconductors 60Y, 60C, and 60M other than black, their toner developing devices, and the intermediate transfer belt 11 can be stopped, and each part deteriorates with time as compared with the case of the normal quadruple tandem. Is less likely to occur.

All of the image adhesion toner adhesion patterns (image adjustment patterns) formed on the plurality of photoreceptors 60B, 60Y, 60C, and 60M including black are transferred onto the intermediate transfer belt 11, and this is transferred to the intermediate transfer belt 11. The image detecting means 210 on the downstream side in the direction can be easily controlled to correct the image density and gradation.
Further, as described above, the photosensitive drum 20B of the black image forming unit 60B (black) does not move in any of the monochrome mode, the full color mode, and the image adjustment pattern mode. For this reason, the exposure position may be the same, and the exposure apparatus (optical unit) 8 can be simplified.

Particularly, since the intermediate transfer belt 11 (first intermediate transfer member) has an endless belt shape and the intermediate transfer roller (second intermediate transfer member) 200 has a roller shape, the switching configuration of the image forming unit can be simplified.
Since the front secondary transfer roller 204 (second transfer body) and the rear secondary transfer roller 66 (first transfer body) are in a roller shape, the number of parts is smaller than in the case of a belt shape, and the cost is reduced. Also, a simple configuration can be achieved.
Further, since the transfer position 57f of the mono-color transfer position toner image onto the recording paper P by the front secondary transfer roller 204 (second transfer body) is on the upstream side in the recording material conveyance direction, the black transfer is first, and the transfer There is no problem that the color color adheres (reverse transfer) to the black photoreceptor through the paper P.

Although the first embodiment of the present invention has been described above, the present invention is not limited to the specific configuration of the embodiment, and various configurations can be made within the scope described in the claims.
For example, as a first modification of the first embodiment, instead of the cams 222, 224, 231 and 236 shown in FIG. 2 and FIG. 4 (a) in order to realize the first to third separation mechanisms 201, 202 and 203, Further, solenoids SL1 to SL4 as shown in FIG. 6 may be used at positions corresponding to them.
Further, as a second modification, the bending levers 220 and 223 of the first separation mechanism 201 shown in FIG. 2 are L-shaped in side view, but instead of this, as shown in FIG. It is good also as flat lever 220 ', 223' supported so that sliding contact is possible to the guide rails 221 and 222 fixed to 230 side.

Further, as a second modification of the first embodiment, as shown in FIG. 7, the entire intermediate transfer belt 11 is supported by a movable base frame 530, and the movable base frame 530 is a plurality of guide rails on the apparatus main body 99 side. 510, the movable base frame 530 is connected to a movable piece of a solenoid SL0 via a plurality of pivot pins 540, and the intermediate transfer belt 11 is vertically moved using the plurality of solenoids SL0. The whole may be switched and supported.
In this case, it is configured to switch between a solid line reference position n1 and a two-point difference line retraction position n2.
When the image forming mode is the monochrome mode, the entire intermediate transfer belt 11 is held at the retracted position n2, thereby holding the intermediate transfer belt 11 at a position corresponding to the second state m2, and in the full color mode, the reference position n1 (the first position). One state m1). In the image adjustment pattern, after being held at the reference position n1, only the bending lever 220 of the first separation mechanism 201 swings to separate the suspension roller 72 from the secondary transfer roller 66, which corresponds to the third state m3. It is possible to obtain the positional deviation information, density, and gradation information of each color of YCMB by the optical detection sensor 210 by holding the position and avoiding the transfer at the secondary transfer position 57r.

  In this case, in the monochrome mode, the stretched surface of the intermediate transfer belt 11 is detached from the plurality of image forming units 60Y, 60C, 60M, and 60B, and in the full color mode, the stretched surface of the intermediate transfer belt 11 is moved to the plurality of image forming units 60Y, The support bracket 530 side is controlled so as to come into contact with 60C, 60M, and 60B and enable primary transfer. However, in some cases, the switching pattern may be changed according to the case where the mode switching pattern changes.

For example, when printing in the full color mode immediately after the monochrome mode, a transfer operation is being performed on the intermediate transfer roller 200 so that the primary transfer can be started immediately using the plurality of image forming units 60Y, 60C, 60M. A plurality of image forming units 60Y, 60C, and 60M remain in contact with each other while the intermediate transfer belt 11 is separated from the black B photosensitive drum 20B by driving the bending lever 223 (see FIG. 2) (driving position n1). ) May be held.
On the other hand, when there is no need to perform full color mode printing or image adjustment pattern mode after operation in the monochrome mode, a plurality of loads are applied to eliminate the load on the intermediate transfer belt 11 due to contact with the photosensitive drum 20. The image forming unit is held at the retracted position n2 so as to hold the separated state.

Furthermore, as a fourth modification of the first embodiment, as shown in FIG. 8, the image forming units 60Y, 60C, and 60M may be arranged in the vertical direction on the left side of the transfer belt 11.
The image forming unit 100f of the fourth modified example includes many overlapping configurations as compared with the image forming unit 100 in the first embodiment. Here, the description of the overlapping members is omitted, and the overlapping members and the members related thereto are the same. A subscript f is added to the symbol. Further, the components of the color digital multi-function peripheral 1 other than the image forming unit 100f are configured in the same manner, and redundant description is omitted.

  In the cases of the first to fourth modifications, the operations of the multiple image forming modes such as the monochrome mode, the full color mode, and the image adjustment pattern mode can be easily achieved. Further, in the case of the full color mode, secondary transfer is performed to the recording material P from the intermediate transfer belt 11 to create a full color image, and in the case of the monochrome mode, secondary transfer is performed to the recording paper P from the intermediate transfer roller 200 to create a monochrome image. In addition, the durability of each of the image forming units 60Y, 60C, and 60M (image forming units) of a plurality of colors can be improved by stopping the intermediate transfer belt 11 when the monochrome image is generated. Since only one unit 60B is required, an increase in cost can be prevented.

Next, an image forming unit 100a that can be employed in the color digital multifunction peripheral 1 as the second embodiment instead of the image forming section 100 that can be employed in the color digital multifunction peripheral 1 according to the first embodiment will be described.
The image forming unit 100a of the second embodiment is shown in FIGS. 9, 10A, and 10B. Note that the image forming unit 100a of the second embodiment includes many overlapping configurations as compared with the image forming unit 100 of the first embodiment. Here, the description of the overlapping members is omitted, and the overlapping members and the members related thereto are omitted. Added the subscript a to the same symbol to simplify the duplicate description. Further, the components of the color digital multi-function peripheral 1 other than the image forming unit 100a are configured in the same manner, and redundant description is omitted.

In the image forming unit 100a of the second embodiment, an intermediate transfer belt 11a as a first intermediate transfer member is rotatably supported in a loop shape at the center of an apparatus main body 99 (see FIG. 1). Includes four color image forming units 60 arranged in series along the belt moving direction A1 of the intermediate transfer belt 11a.
Here, the order of the image forming units 60B (black) is located on the most upstream side with respect to the other image forming units 60Y (yellow), 60C (cyan), and 60M (magenta), and is opposite to the first embodiment. This is different from the first embodiment. The rotation direction A1 of the intermediate transfer belt 11a and the flow path direction of the transport path R are the same as those in the first embodiment.

  Further, transfer positions 57f and 57r are set at two positions in the front and rear of the intermediate transfer belt 11 in the flow path direction of the transport path R. The front secondary transfer position 57f faces the secondary transfer roller 66a that is the first transfer body, and the rear secondary transfer position 57r faces the secondary transfer roller 204a that is the second transfer body. That is, the positions of the secondary transfer roller (second transfer member) 66a and the rear secondary transfer roller (first transfer member) 204a here are opposite to those in the first embodiment, and the conveyance path R When the image forming mode is in the full color mode on the upstream side in the flow path direction, a pre-secondary transfer position 57f for secondary transfer of the full-color toner image is provided, and the image is formed on the downstream side in the flow path direction of the transport path R. When the formation mode is the monochrome mode, a secondary transfer position 57r is provided after the secondary transfer of the black toner image.

Further, the intermediate transfer belt 11a in this state is reversed in the up-down direction by switching in the same manner in the state where the stretching position is vertically reversed by the first separation mechanism 201a, the second separation mechanism 202a, and the third separation mechanism 203a. Thus, the intermediate transfer belt 11 is switched to the first state m1, the second state m2, and the third state (third suspension state) m3.
Here, as shown in FIG. 9, when the image forming mode is in the full color mode, the suspension roller 72 is held at the drive position P11 and the intermediate transfer belt 11a contacts the front secondary transfer roller 66a (second transfer member). In contact with each other, the suspension roller 33 and the primary transfer roller 12B are both switched to the drive position (solid line position) P21, whereby the first state (first suspension state) m1 is maintained. At the same time, the intermediate transfer roller (second intermediate transfer member) 200a is released from the black 20B photosensitive member to the separation position P32, and the rear secondary transfer roller 204a (first transfer member) is separated from the position s1 for primary transfer to the recording paper P. Switch to position s2.

  Further, as shown in FIG. 10A, when the image forming mode is the monochrome mode, the suspension roller 72 reaches the separation position P12 and is separated from the front secondary transfer roller 66a, and the suspension roller 33 and the primary transfer roller 12B are removed. The second state (second state) m2 is held by switching to the separation position P22. At the same time, the intermediate transfer roller (second intermediate transfer member) 200a is switched to the drive position P31 in contact with the black 20B photoconductor, and the rear secondary transfer roller (second transfer member) 204a is switched to the position s1 for primary transfer to the recording paper P. .

Further, as shown in FIG. 10B, when the image forming mode is the image adjustment pattern mode, the suspension roller 72 reaches the separation position P12 and is separated from the front secondary transfer roller 66a, and the suspension roller 33 and the primary transfer are transferred. The third state (third suspended state) m3 (see FIG. 10B) is held by holding the driving position P21 together with the rollers 12B. At the same time, the intermediate transfer roller (second intermediate transfer member) 200a is switched to the separation position P32 from the black 20B photosensitive member, and the rear secondary transfer roller 204a (first transfer member) is switched to the separation position s2.
It should be noted that control for switching the intermediate transfer belt 11 to the first to third states m1 to m3 using the first to third separation mechanisms 201, 202, and 203, and secondary transfer positions 57f before and after the conveyance path R, The control of the secondary transfer selectively performed at 57r is performed by the control unit 500. Such a second embodiment can obtain substantially the same operational effects as the first embodiment.

Next, instead of the image forming unit 100 that can be employed in the color digital multifunction peripheral 1 in the first embodiment, an image forming unit 100b that can be employed in the color digital multifunction peripheral 1 as the third embodiment will be described.
The image forming unit 100b of the third embodiment is shown in FIGS. 11 (a), 11 (b), and 12. FIG. Note that the image forming unit 100b of the third embodiment includes many overlapping configurations as compared with the image forming unit 100 of the first embodiment. Here, the description of the overlapping members is omitted, and the overlapping members and the members related thereto are omitted. Added the subscript b to the same symbol to simplify the duplicate description. Further, the components of the color digital multi-function peripheral 1 other than the image forming unit 100b are configured in the same manner, and redundant description is omitted.

  In the image forming unit 100b of the third embodiment, an intermediate transfer belt 11b, which is a first intermediate transfer body, is rotatably supported in a loop shape at the center of an apparatus main body 99 (see FIG. 1). On the side, image forming units 60Y, 60C, 60M, and 60B for four colors are arranged in series along the belt movement direction A1 of the intermediate transfer belt 11b. Further, the tension position of the intermediate transfer belt 11b here is changed by the first separation mechanism 201 in the first state m1 (shown in FIG. 11A), the second state m2 (shown in FIG. 11B), the third state. The front and rear transfer positions 57fb and 57rb are set at two points in the front and rear in the rotation direction A1 of the intermediate transfer belt 11b and the flow path direction of the conveyance path R, and the point (the third suspension state) m3 (shown in FIG. 12). This is the same as the first embodiment. Further, each of the first to third separation mechanisms 201b to 203b is formed by adopting the same configuration as the mechanism forming the first embodiment, but redundant description is omitted here.

  Here, in particular, the primary transfer position Pf1 of the black photosensitive member 20B, which is one latent image carrier, and the intermediate transfer belt 11b (in the case of being described in common with other photosensitive members, the symbol a as shown in FIG. 19B). The intermediate transfer roller (second intermediate transfer member) 200b is provided between the intermediate transfer roller 200b and the intermediate transfer roller 200b.

  This intermediate transfer roller (second intermediate transfer member) 200b is primary-transferred to the intermediate transfer belt (first intermediate transfer member) 11b in the first state m1 after the toner image temporarily transferred from the black 20B photosensitive member prior to the primary transfer. The primary transfer feed state in which primary transfer is performed at the transfer position Pf1 (the state held by the symbol e1 in FIG. 19B) and the state separated from the primary transfer feed state (the state held in the symbol e2 in FIG. 19B) ) And the second separation mechanism 202b.

Further, the front secondary transfer roller (second transfer body) 204b is disposed opposite to the position of the intermediate transfer roller (second intermediate transfer body) 200b on the black 20B photoconductor. Here, the front transfer roller (second transfer member) 204b is switched by the third separation mechanism 203b between a position s1 for primary transfer onto the recording paper P and a position s2 separated from the same position.
Further, a rear transfer roller 66b, which is a first transfer body, is disposed at the rear transfer position 57rb on the downstream side in the flow path direction of the transport path R so as to face the suspension roller 72 via the intermediate transfer belt 11b.

  Here, when the image forming mode is the full color mode, the intermediate transfer belt 11 is switched to the first state m1. As shown in FIG. 11A, the suspension roller 72 reaches the driving position P11 where the intermediate transfer belt 11 comes into contact with the rear transfer roller 66b, and holds it so as to be capable of secondary transfer. Further, the suspension roller 33 and the primary transfer roller 12B are both switched to the driving position (solid line position) P21, so that the first state m1 is maintained.

  At the same time, the intermediate transfer roller 200b preliminarily transfers the toner image temporarily transferred from the black photoconductor 20B, which is one latent image carrier, to the intermediate transfer belt 11 in the first state m1 at the primary transfer position Pf1. The primary transfer feeding state for primary transfer (the state shown in FIG. 11A) is maintained. Further, the front transfer roller 204b at the front transfer position 57fb is switched and held at the separation position s2. Thus, when the image forming mode is the full color mode, the full color toner image can be secondarily transferred to the recording paper P at the post-transfer position 57rb.

When the image forming mode is the monochrome mode, the intermediate transfer belt 11 is held in the second state (second state) m2. As shown in FIG. 11B, the suspension roller 72 is switched to the separation position P12 where the intermediate transfer belt 11 is separated from the rear transfer roller 66b, and the suspension roller 33 and the primary transfer roller 12B are both switched to the separation position P22. In the second state (second state) m2.
Further, the intermediate transfer roller 200b is held in a detached state (the state shown in FIG. 11B) that is separated from the primary transfer feeding state (the state shown in FIG. 11A) where the primary transfer is performed at the primary transfer position Pf1. At the same time, the front transfer roller 204b at the front transfer position 57fb is held at the drive position s2. Thus, when the image forming mode is the monochrome mode, the black toner image can be primarily transferred (directly transferred) to the recording paper P at the front transfer position 57fb.

  When the image forming mode is the image adjustment pattern mode, the intermediate transfer belt 11 is held in the third state m3. Here, as shown in FIG. 12, the intermediate transfer roller 200b transfers the toner image, which has been temporarily transferred from the black photoreceptor 20B prior to the primary transfer, to the intermediate transfer belt 11 in the third state m3 at the primary transfer position Pf1. The primary transfer feed state for primary transfer (the state shown in FIG. 12) is maintained. Further, the suspension roller 72 is switched to the separation position P12 where the intermediate transfer belt 11 is separated from the rear transfer roller 66b, and the suspension roller 33 and the primary transfer roller 12B are switched together to the driving position P21, so that a plurality of latent image carriers are formed. It is held in the third state m3 in which it is abutted at the primary transfer position (while it is left) and is separated from the rear transfer roller 66b. At the same time, the front transfer roller 204b at the front transfer position 57fb is switched and held at the separation position s2.

Control for switching the intermediate transfer belt 11b to the first to third states m1 to m3 using the first to third separation mechanisms 201b, 202b, and 203b, and a secondary transfer position 57fb before and after the conveyance path R. , 57rb selectively transfer control is performed by the control unit 500 (see FIG. 1).
Such a third embodiment can obtain substantially the same operational effects as the first embodiment. In particular, by directly transferring the toner image visualized on the black photoreceptor 20B, which is one of the plurality of latent image carriers, onto the recording paper P, a monochrome mode toner image can be obtained. The primary transfer is directly performed on the recording paper P to obtain a good monochrome image, and the durability of the multi-color image forming units 60Y, 60C and 60M can be prevented and the cost can be prevented from increasing. Further, in the monochrome mode, the intermediate transfer belt 11b is switched to the second state m2 by the first separation mechanism, and the front secondary transfer roller 204b is moved to a position e2 where the intermediate transfer roller 200b is separated from the primary transfer feed state by the second separation mechanism. Can be reliably switched to the position where the first transfer is performed by the third separation mechanism. In addition, each component is less likely to deteriorate with time compared to a normal quadruple tandem.

  Further, in the image adjustment pattern mode, the intermediate transfer belt 11b is switched to the third state m3, the intermediate transfer roller 200b is switched to the primary transfer feed state, and the front secondary transfer roller 204b is switched from the position for primary transfer to the position s2. As a result, it is possible to transfer all of the image adjustment toner adhesion patterns (image adjustment patterns) formed on the plurality of image carriers including black onto the intermediate transfer member, and this can be transferred in the running direction A1 of the intermediate transfer member. The image detecting means 210 on the downstream side can easily detect and control the correction of the image density and gradation.

Next, an image forming unit 100c that can be employed in the color digital multifunction peripheral 1 as the fourth embodiment in place of the image forming section 100 that can be employed in the color digital multifunction peripheral 1 in the first embodiment will be described.
The image forming unit 100c of the fourth embodiment is shown in FIGS. 13 (a), 13 (b), and 14. FIG.

  The image forming unit 100c according to the fourth embodiment includes many overlapping configurations as compared with the image forming unit 100 according to the first embodiment. Here, the description of the overlapping members is omitted, and the overlapping members and the members related thereto are omitted. Added the subscript c to the same symbol to simplify the duplicate description. Further, the components of the color digital multi-function peripheral 1 other than the image forming unit 100c are configured in the same way, and redundant description is omitted.

  In an image forming unit 100c according to the fourth embodiment, an intermediate transfer belt 11c is rotatably supported in a loop shape at the center of an apparatus main body 99 (see FIG. 1), and an intermediate transfer belt 11c is provided below the intermediate transfer belt 11c. The image forming units 60Y, 60C, and 60M for three colors are arranged in series along the belt moving direction A1, and the downstream side of the three image forming units 60 is above the intermediate transfer belt 11c. A black B image forming unit 60B is provided. In response to this, a suspension roller 72 is disposed downstream of the three image forming units 60 and below the intermediate transfer belt 11c, and a suspension roller 33 is disposed downstream of the intermediate transfer belt 11c. This is different from the first and third embodiments.

In particular, the photoconductor 20B of the image forming unit 60B here is disposed at a position facing the primary transfer roller 12B in the upper portion of the intermediate transfer belt 11c via the intermediate transfer roller (second intermediate transfer body) 200c. A first transfer position Pf1 for black B is set, which is different from the first and third embodiments.
As shown in FIG. 13 (a), the intermediate transfer roller 200c is primary-transferred from the black photoreceptor 20B to the intermediate transfer belt 11c in the first state m1 at the primary transfer position Pf1. A second transfer state (a state held at reference numeral e1 in FIG. 13A) and a state separated from the primary transfer feed state (a state held at reference numeral e2 in FIG. 13B) are second. It is switched by the separation mechanism 202c.

Further, a secondary transfer roller (second transfer member) 204c is disposed opposite to the black photosensitive member 20B at a position different from the position of the intermediate transfer roller (second intermediate transfer member) 200c. Here, the secondary transfer roller (second transfer member) 204c is switched by the third separation mechanism 203c between a position s1 for secondary transfer onto the recording paper P and a position s2 that is detached from the same position.
In the image forming unit 100c according to the fourth embodiment, the tension position of the intermediate transfer belt 11c is set to the first state m1 (shown in FIG. 13A) and the second state m2 (see FIG. 13A) by the first separation mechanism 201c. b), the point where the state is switched to the third state m3 (shown in FIG. 14), and the front and rear transfer positions 57fc and 57rc at the front and rear two positions in the rotation direction A1 of the intermediate transfer belt 11c and the flow path direction of the transport path R. Is the same as that of the first embodiment.

Here, when the image forming mode is the full color mode, as shown in FIG. 13A, the suspension roller 72 is at the drive position P11, and the suspension roller 33 and the primary transfer roller 12B are both at the drive position (solid line position) P21. By switching, it is held in the first state (first suspension state) m1, and the suspension roller 72 reaches the drive position P11 where the intermediate transfer belt 11 contacts the front transfer roller 66c, and is held so as to be capable of secondary transfer.
At the same time, the intermediate transfer roller 200c performs a primary transfer feeding state in which the toner image, which has been temporarily primary transferred from the black photoreceptor 20B prior to the primary transfer, is primarily transferred to the intermediate transfer belt 11 in the first state m1 at the primary transfer position Pf1. The state shown in FIG. Further, the rear transfer roller 204c of the rear transfer position 57rc is switched and held at the separation position s2. Accordingly, when the image forming mode is the full color mode, the full color toner image can be secondarily transferred to the recording paper P at the front transfer position 57fb.

When the image forming mode is the monochrome mode, the intermediate transfer belt 11 is held in the second state (second state) m2. As shown in FIG. 13B, the suspension roller 72 is switched to the separation position P12 where the intermediate transfer belt 11 is separated from the front transfer roller 66c, and the suspension roller 33 and the primary transfer roller 12B are both switched to the separation position P22. In the second state (second state) m2.
At the same time, the intermediate transfer roller 200b is held in a detached state (the state shown in FIG. 13B) that is separated from the primary transfer position Pf1. Further, the rear transfer roller 204c of the rear transfer position 57rb is switched to the drive position s2. Thus, in the monochrome mode, the black toner image can be primarily transferred (directly transferred) to the recording paper P at the post-transfer position 57rb.

When the image forming mode is the image adjustment pattern mode, the intermediate transfer belt 11c is held in the third state m3. Here, as shown in FIG. 14, the intermediate transfer roller 200 c transfers the toner image temporarily transferred from the black photoreceptor 20 B prior to the primary transfer to the intermediate transfer belt 11 in the third state m 3 at the primary transfer position Pf 1. The primary transfer feeding state for primary transfer (the state shown in FIG. 14) is maintained. At the same time, the rear transfer roller 204c of the rear transfer position 57rc is switched and held at the separation position s2.
Further, the suspension roller 72 is switched to the separation position P12 where the intermediate transfer belt 11c is separated from the front transfer roller 66c, and the suspension roller 33 and the primary transfer roller 12B are switched together to the driving position P21, thereby forming a plurality of latent image carriers. It is held in the third state m3 in which it is in contact with the primary transfer position a (while it is still) and is separated from the front and rear transfer rollers 66c and 204c.

  In the image adjustment pattern mode, the supply of the recording paper P is stopped, and the latent image is transferred onto the intermediate transfer belt 11 in accordance with an image signal of a four-color image adjustment pattern or a density gradation pattern by density adjustment lines or dots. An image is formed, and a toner image of each color is formed by each developing device. Further, each toner image is formed on the intermediate transfer belt 11 c by the primary transfer, and each color toner image passes through the downstream secondary transfer position 57 r and approaches the image detection unit 210 in the vicinity of the suspension roller 72. The image detection unit 210 can easily perform control for correcting the image density and gradation according to the detected toner image of each color.

Control for switching the intermediate transfer belt 11c to the first to third states m1 to m3 using the first to third separation mechanisms 201c, 202c, and 203c, and a secondary transfer position 57fc before and after the conveyance path R. , 57rc and the transfer control selectively performed by the controller 500 (see FIG. 1).
In the fourth embodiment, substantially the same operational effects as those in the first and third embodiments can be obtained. In particular, in the full color mode, the full color toner image is transferred to the recording paper P at the upstream front transfer position 57fc in the flow path direction of the conveyance path R, and in the monochrome mode, the black toner image is recorded at the downstream rear transfer position 57rc. It can be transferred onto the paper P, and in this respect, it is possible to have a configuration upside down with respect to the third embodiment.

Next, an image forming unit 100d that can be employed in the color digital multifunction peripheral 1 as the fifth embodiment in place of the image forming section 100 that can be employed in the color digital multifunction peripheral 1 according to the first embodiment will be described.
The image forming unit 100d of the fifth embodiment is shown in FIGS. 15 (a), 15 (b), and 16. FIG.

  Note that the image forming unit 100d of the fifth embodiment includes many overlapping configurations as compared with the image forming unit 100 of the first embodiment. Here, the description of the overlapping members is omitted, and the overlapping members and the members related thereto are omitted. Added the suffix d to the same symbol to simplify the duplicate description. Further, the components of the color digital multi-function peripheral 1 other than the image forming unit 100d are configured in the same way, and redundant description is omitted.

  In the image forming unit 100d according to the fifth embodiment, an intermediate transfer belt 11d is loopably supported in a central portion of the apparatus main body 99 (see FIG. 1) in a loop shape. The intermediate transfer belt 11d rotates in the clockwise direction, and the image forming units 60B, 60Y, 60C, and 60M for four colors are arranged in series along the belt moving direction A2 below the intermediate transfer belt 11d. Here, the rotation direction of the photosensitive member 20 in the image forming unit 60 is counterclockwise, and the positions of the developing device, the cleaning device, and the charging device are reversed from those in the first embodiment. An intermediate transfer roller (second intermediate transfer member) 200d is provided on the downstream side of the four image forming units 60 and on the upper side of the intermediate transfer belt 11c. This is different from the first embodiment.

Here, the tension position of the intermediate transfer belt 11d is changed to the first state m1 (shown in FIGS. 15A and 16) and the second state m2 (shown in FIG. 15B) by the first separation mechanism 201d. And the third state m3 is eliminated, which is different from the first embodiment in this respect. Further, the present embodiment is the same as the first embodiment in that front and rear transfer positions 57fd and 57rd are set at two front and rear positions in the flow path direction of the transport path R.
Further, in the image forming unit 100d of the fifth embodiment, the suspension roller 33 is disposed on the upstream side of the four image forming units 60 of the intermediate transfer belt 11d, and the suspension roller 72 is further disposed on the upstream side thereof. The suspension roller 72 and the intermediate transfer roller (second intermediate transfer member) 200d are in contact with each other with the intermediate transfer belt 11d interposed therebetween.

  As shown by the solid line in FIG. 15A, the intermediate transfer roller (second intermediate transfer member) 200d is temporarily secondary at the temporary secondary transfer position pd prior to the secondary transfer from the intermediate transfer belt 11d in the first state m1. The transferred full-color toner image is transferred to a secondary transfer position 57rd which is a position different from the temporary secondary transfer position pd. Further, the intermediate transfer roller 200d faces the rear transfer roller (first transfer body) 66d so as to be able to contact and separate at the secondary transfer position 57rd.

  At this time, the intermediate transfer roller 200d uses the post-transfer roller (first transfer body) 66d as the recording material P in the transport path R by transferring the temporary secondary transfer full-color toner image to the secondary transfer position 57rd. Then, it is switched and held in the secondary feed transfer state in which the secondary transfer is performed (the state indicated by the symbol e1 in FIG. 15A and the symbol e1 in FIG. 19C). The intermediate transfer roller 200d maintains a state where the toner image is temporarily transferred at the temporary secondary transfer position pd, and is separated from the secondary feed transfer state (see symbol e2 in FIG. 15B). Is switched by the second separation mechanism 202d.

  On the other hand, the black photoconductor 20B provided at a position upstream of the other photoconductors 20 has a front transfer roller (in a position different from the position of the intermediate transfer belt 11d (first intermediate transfer body)). The second transfer member 204d is disposed opposite to the front transfer position 57fd. Here, the front transfer roller 204d is switched by a third separation mechanism 203d between a position s1 (see FIG. 15B) for primary transfer onto the recording paper P and a position s2 (see FIG. 15A) separated from the same position. It is done.

  Here, when the image forming mode is the full color mode, as shown in FIG. 15A, the suspension roller 72 is switched to the drive position P11, and the suspension roller 33 and the primary transfer roller 12B are switched to the drive position (solid line position) P21. In other words, the intermediate transfer belt 11d is held in the first state m1. At the same time, the intermediate transfer roller 200d transfers the toner image temporarily transferred at the temporary secondary transfer position pd prior to the secondary transfer from the intermediate transfer belt 11d to the rear secondary transfer position 57rd to transfer the recording material P on the conveyance path R. In addition, the secondary transfer transfer state (see FIG. 15A) in which secondary transfer can be performed using the post-transfer roller 66d is switched and held.

At the same time, the front transfer roller 204d at the front transfer position 57fd is switched and held at the separation position s2. As a result, the image forming mode is maintained in the full color mode, and the full color toner image is secondarily transferred to the recording paper P at the post-transfer position 57rd.
When the image forming mode is the monochrome mode, the intermediate transfer belt 11d is held in the second state (second state) m2. As shown in FIG. 15 (b), the suspension roller 72 and the primary transfer roller 12B are switched to the separation position P22 while the suspension roller 72 remains at the driving position P11, so that the second state (second state) m2 is maintained. The At the same time, the intermediate transfer roller 200d is switched to the temporary secondary transfer position pd by the second separation mechanism 202d from the secondary feed transfer state (see FIG. 15B). Further, the front transfer roller 204d at the front transfer position 57fd is switched to the drive position s1 where it contacts the photoconductor 20B. Thus, in the monochrome mode, the black toner image can be primarily transferred (directly transferred) to the recording paper P at the front transfer position 57fd from the photoreceptor 20B. At this time, the intermediate transfer belt 11d is stopped or idly rotated.

When the image forming mode is the image adjustment pattern mode, the intermediate transfer belt 11d is held in the first state m1. Here, as shown in FIG. 16, the intermediate transfer roller 200d is in the temporary secondary transfer position pd, and the rear transfer roller (first transfer body) 66d is separated from the secondary feed transfer state by the second separation mechanism 202d. (See FIG. 16). At the same time, the front transfer roller 204d at the front transfer position 57fd is switched and held at the separation position s2 by the third separation mechanism 202d.
In this case, as shown in FIG. 16, the intermediate transfer roller 200d is provided with an image detecting means 210 close to the downstream side of the position pd where temporary secondary transfer is performed in the rotational direction, and the belt cleaning device 13 ( The same configuration as that shown in FIG. 1 is adopted.

In this case, a latent image is formed on the photoconductor 20 of each color according to the image signal of the density adjustment pattern of four color image adjustment patterns or density adjustment lines or dots. It is formed. Further, each toner image is formed on the intermediate transfer belt 11d by the primary transfer, and the toner images of the respective colors are temporarily transferred to the intermediate transfer roller 200d at the downstream temporary secondary transfer position pd.
The intermediate transfer roller 200d rotates in a state where the intermediate transfer roller 200d is disengaged from the secondary feed transfer state (see FIG. 16), and transfers the temporarily secondary transferred toner image to the image detection unit 210. The image detection unit 210 can easily perform control for correcting the image density and gradation in accordance with the detected toner image of each color, and then the toner image of each color is removed by the belt cleaning device 13 on the downstream side.

  Such a fifth embodiment can obtain substantially the same operational effects as the first embodiment. In particular, the first separation mechanism 201d is only switched to the first and second states, and the apparatus can be simplified. Further, in the image adjustment pattern mode, the intermediate transfer belt 11d is held in the first state m1 by the first separation mechanism 201d and the intermediate transfer roller 200d is temporarily moved to the temporary secondary transfer position pd by the second separation mechanism 202d. After the next transfer, the secondary transfer transfer state is switched to the released state (see FIG. 16). At the same time, the image transfer pattern mode can be easily achieved by switching and holding the front transfer roller 204d at the front transfer position 57fd to the separation position s2. In addition, all of the image adjustment toner adhesion patterns (image adjustment patterns) formed on the plurality of image carriers including black are transferred onto the intermediate transfer roller 200d, which is downstream in the rotation direction of the intermediate transfer roller 200d. The image detecting means 210 can easily detect and control the image density and gradation.

Next, an image forming unit 100e that can be employed in the color digital multifunction peripheral 1 as the sixth embodiment instead of the image forming unit 100 that can be employed in the color digital multifunction peripheral 1 according to the first embodiment will be described.
The image forming unit 100e of the sixth embodiment is shown in FIGS. 17 (a), 17 (b), and 18. FIG.

  Note that the image forming unit 100e of the sixth embodiment includes many overlapping configurations as compared with the image forming unit 100 of the first embodiment. Here, the description of the overlapping members is omitted, and the overlapping members and the members related thereto are omitted. Added the subscript e to the same symbol to simplify the duplicate description. Further, the components of the color digital multi-function peripheral 1 other than the image forming unit 100e are configured in the same manner, and redundant description is omitted.

In the image forming unit 100e of the sixth embodiment, an intermediate transfer belt 11e is supported in a central portion of the apparatus main body 99 (see FIG. 1) in a loop shape so as to be rotatable in the clockwise direction. The intermediate transfer belt 11e is provided with the image forming units 60 of three color image forming units 60Y, 60C, 60M in series along the belt moving direction A2 at the lower portion thereof, and downstream of the three image forming units 60. Thus, the black B image forming unit 60B is disposed on the upper side of the intermediate transfer belt 11e. Accordingly, a suspension roller 72 is disposed on the upstream side of the three image forming units 60 and below the intermediate transfer belt 11e, and a suspension roller 33 is disposed on the intermediate transfer belt 11e.
The photoconductor 20B of the image forming unit 60B and the primary transfer roller 12B facing the photoconductor 20B are arranged on the upper portion of the intermediate transfer belt 11e, which sets the primary transfer position Pf1 for black B, which is the first embodiment. Is different.

  Here, the tension position of the intermediate transfer belt 11e is switched to the first state m1 (shown in FIG. 17A) and the second state m2 (shown in FIG. 17B) by the first separation mechanism 201e. The tristate m3 is eliminated and is different from the first embodiment in this respect. Here, in the second state m2, the suspension roller 33 and the primary transfer roller 12B are switched from the drive position P21 to the separation position P22, and at the same time, the suspension roller 72 is separated from the drive position P11 contacting the intermediate transfer roller 200e to the separation position P12. Switch. Note that this is the same as in the first embodiment in that front and rear transfer positions 57fe and 57re are set at two front and rear positions in the flow path direction of the transport path R.

As shown by a solid line in FIG. 17A, the intermediate transfer roller (second intermediate transfer member) 200e contacts the suspension roller 72 with the intermediate transfer belt 11e interposed therebetween.
The intermediate transfer roller 200e transfers the full-color toner image temporarily transferred at the temporary secondary transfer position pd prior to the secondary transfer from the intermediate transfer belt 11e in the first state m1 to the front transfer position 57fe. Further, the intermediate transfer roller 200e faces the front transfer roller (first transfer body) 204e at a front transfer position 57fe that is different from the temporary secondary transfer position pd.

Here, the intermediate transfer roller 200e transfers the full-color toner image temporarily transferred at the temporary secondary transfer position pd prior to the secondary transfer from the intermediate transfer belt 11e in the first state m1 to the previous transfer position 57fe. The recording material P in the conveyance path R is held in a secondary feed transfer state (state indicated by a solid line in FIG. 17A) that can be secondary transferred using the front transfer roller 204e.
Here, in particular, instead of the intermediate transfer roller 200e disposed opposite to the front transfer position 57fe, the front transfer roller 204e is switched by the second separation mechanism 202e between the transfer position e1 and the separation position e2 where the front transfer position 57fe is separated. Retained.

Thus, when the front transfer roller 204e is switched to the separation position e2, the intermediate transfer roller 200e is held at the temporary secondary transfer position pd in a state of separation from the secondary feed transfer state (see FIG. 18). At the same time, the rear transfer roller 66e of the rear transfer position 57rd is switched and held at the separation position s2 by the third separation mechanism 203e.
In this case, as shown in FIG. 18, the intermediate transfer roller 200e is provided with an image detecting unit 210 close to the downstream side of the position pd where temporary secondary transfer is performed in the rotational direction, and the belt cleaning device 13 ( The same configuration as that shown in FIG. 1 is adopted.

  When the image forming mode is the full color mode, as shown in FIG. 17A, the suspension roller 72 is switched to the drive position P11, and the suspension roller 33 and the primary transfer roller 12B are switched to the drive position (solid line position) P21. Change. At the same time, the intermediate transfer roller 200e can transfer the toner image temporarily secondary transferred from the intermediate transfer belt 11e to the front secondary transfer position 57fe, and can be secondarily transferred to the recording material P in the conveyance path R using the front transfer roller 204e. The secondary feed transfer state (see FIG. 17A)) is maintained.

At the same time, the rear transfer roller 66e of the rear transfer position 57re is switched to the separation position s2 and held. As a result, the image forming mode is maintained in the full color mode, and the full color toner image is secondarily transferred to the recording paper P at the front transfer position 57fe.
When the image forming mode is the monochrome mode, as shown in FIG. 17B, the suspension roller 72 is switched to the separation position P12, and the suspension roller 33 and the primary transfer roller 12B are switched to the separation position P22. Retained. At the same time, the front transfer roller 204e at the front transfer position 57fe is switched to the second separation mechanism 202e at the separation position e2. Further, the post-transfer roller 66e is switched to the drive position s1 in contact with the photoconductor 20B.
Thereby, in the monochrome mode, the black toner image can be primarily transferred (directly transferred) to the recording paper P at the rear transfer position 57re from the photoreceptor 20B. At this time, the intermediate transfer belt 11e is stopped.

When the image forming mode is the image adjustment pattern mode, as shown in FIG. 18, the front transfer roller 204e at the front transfer position 57fe is held at the separation position e2, and the intermediate transfer roller 200e is at the temporary secondary transfer position pd. Thus, the black toner image is switched from the photosensitive member 20B to the intermediate transfer belt 11e at the primary transfer position Pf1 at the primary transfer position Pf1.
In this case, a latent image is formed on the photoconductor 20 of each color according to the image signal of the density adjustment pattern of four color image adjustment patterns or density adjustment lines or dots, and a toner image of each color is formed by each developing device. It is formed. Further, each toner image is formed on the intermediate transfer belt 11d by the primary transfer, and the toner images of the respective colors are temporarily transferred to the intermediate transfer roller 200e at the downstream temporary secondary transfer position pd.
The intermediate transfer roller 200e rotates in a state where the intermediate transfer roller 200e is separated from the secondary feed transfer state (see FIG. 18), and transfers the temporarily secondary transferred toner image to the image detection unit 210. The image detection unit 210 can easily perform control for correcting the image density and gradation in accordance with the detected toner image of each color, and then the toner image of each color is removed by the belt cleaning device 13 on the downstream side.

  Such a sixth embodiment can obtain substantially the same operational effects as the first embodiment. In particular, the first separation mechanism 201d is only switched to the first and second states, and the apparatus can be simplified. Further, in the image adjustment pattern mode, the intermediate transfer belt 11d is held in the first state m1 by the first separation mechanism 201d, and the front transfer roller 204e is switched to the separation position s2, not the intermediate transfer roller, by the second separation mechanism 202d. As a result, the intermediate transfer roller 200e can maintain a state (see FIG. 18) in which the toner image is temporarily transferred to the secondary image and then separated from the secondary feed transfer state. At the same time, the image transfer pattern mode can be easily achieved by switching and holding the post-transfer roller 66e at the post-transfer position 57re to the separation position s2. In addition, all the image adjustment toner adhesion patterns (image adjustment patterns) formed on the plurality of image carriers including black are transferred onto the intermediate transfer roller 200e, and this is downstream of the rotation direction of the intermediate transfer roller 200e. The image detecting means 210 can easily detect and control the image density and gradation.

Next, the configurations of the image forming units 100 to 100e used in the color digital multi-function peripheral 1 described as the first, third, and fifth embodiments are described with reference to FIGS. The explanation will be made after collecting each common part. It is to be noted that claims 19 and 20 are provided in consideration of the aggregated configuration.
Here, as shown in FIG. 19A, the image forming unit 100 of the first embodiment is in the first mode (monochrome mode), that is, when the first separation mechanism 201 is in the second state m2. A toner image is formed on the black photosensitive member 20B (first latent image carrier), and recording is performed using the intermediate transfer roller (second intermediate transfer member) 200 without the intermediate transfer belt 11 (first intermediate transfer member). A black toner image is transferred to the paper P.

On the other hand, in the second mode (full color mode), that is, when the first separation mechanism 201 is in the first state m1, a plurality of photoconductors other than black on the black photoconductor 20B (first latent image carrier). Color toner images are formed on 20Y, 20C, and 20M (a plurality of color photosensitive drums), and after these toner images are transferred onto the intermediate transfer belt 11 (first intermediate transfer body), the intermediate transfer belt 11 is used. The toner image is transferred onto the recording paper P using a post-transfer roller (first transfer body) 66.
In both the first mode and the second mode, a full-color toner image is transferred onto the same side (left side in FIG. 19) of the recording paper P.

Next, with respect to the image forming unit 100b of the third embodiment, as shown in FIG. 19B, when in the first mode (monochrome mode), that is, when the first separation mechanism 201b is in the second state m2. After the toner image is formed on the black photosensitive member 20B, the third separation mechanism 203b directly switches the front transfer roller (second transfer member) 204b to the driving position s1, so that the black toner is applied to the recording paper P. Transfer the image.
On the other hand, in the second mode (full color mode), that is, when the first separation mechanism 201b is in the first state m1, a black toner image is formed on the black photoreceptor 20B, and this is transferred to the intermediate transfer roller (first transfer mode). A second intermediate transfer member) 200b is transferred onto the intermediate transfer belt 11b (first intermediate transfer member), and at the same time, a color toner image is formed on a plurality of photoconductors 20Y, 20C, and 20M other than black. The toner image is transferred onto the intermediate transfer belt 11b (first intermediate transfer member), and then the toner image on the intermediate transfer belt 11b is transferred onto the recording paper P using a rear transfer roller (first transfer member) 66b.
Also in this case, the full-color toner image is transferred onto the same side (left side in FIG. 19) of the recording paper P in both the first mode and the second mode.

Next, regarding the image forming unit 100d of the fifth embodiment, as shown in FIG. 19C, when in the first mode (monochrome mode), that is, when the first separation mechanism 201d is in the second state m2. After the toner image is formed on the black photoconductor 20B, the third separation mechanism 203d directly switches the front transfer roller (second transfer body) 204d to the driving position s1, so that the black toner is applied to the recording paper P. Transfer the image.
On the other hand, in the second mode (full color mode), that is, when the first separation mechanism 201d is in the first state m1, a black toner image is formed on the black photoreceptor 20B, and this is formed on the intermediate transfer belt 11d. At the same time, a color toner image is formed on a plurality of photoconductors 20Y, 20C, and 20M other than black, and this is transferred onto an intermediate transfer belt 11d. The toner image on the intermediate transfer belt 11d is transferred to an intermediate transfer roller. (Second intermediate transfer member) Transferred from the temporary secondary transfer position to the secondary transfer position via 200d, and then transferred to the recording paper P via the rear transfer roller (first transfer member) 66d.

Also in this case, the full-color toner image is transferred onto the same side (left side in FIG. 19) of the recording paper P in both the first mode and the second mode.
Here, in the fifth embodiment (in the case of FIG. 19C), the rotation direction of the intermediate transfer belt 11 (first intermediate transfer member) and the plurality of photoconductors 20 is reverse to that of the first and third embodiments. . Further, in the first embodiment (in the case of FIG. 19A), the black photoconductor 20B rotates clockwise, and in the third and fifth embodiments, the black photoconductor 20B rotates counterclockwise. Furthermore, the intermediate transfer roller (second intermediate transfer member) 200 of the first and fifth embodiments rotates clockwise, and in the third embodiment (in the case of FIG. 19B), it rotates clockwise.

Any of these configurations (Examples 1 to 6) has the following effects.
In the first mode, the intermediate transfer belt 11 (first intermediate transfer member) can be stopped. Therefore, the conventional tandem intermediate transfer system, for example, the photoreceptors of the image forming units of all colors are provided facing the intermediate transfer belt (intermediate transfer body), and the toner images of all the photoreceptors are always intermediate transfer bodies. In the case of adopting a method of transferring to a recording material via the intermediate transfer member, for example, it is necessary to rotate the intermediate transfer member even in the monochrome mode using only one black photosensitive member. Compared with such a conventional tandem intermediate transfer system, the second latent image carrier and the intermediate transfer body are less likely to deteriorate, and these members can have a longer life.

  Furthermore, since the toner image is transferred to the same side of the recording material regardless of the mode, the first mode and the second mode can be switched for each recording material during the output of multiple sheets. When a plurality of originals to be printed include a mixture of monochrome pages and full-color pages, for example, the image forming surfaces of recording materials can be output together. There is no need to invert the recording material before output in accordance with the mode switching, and an easy-to-use image forming operation can be realized with a simple configuration.

  In addition, regardless of the first mode and the second mode, the rotation direction on the first latent image carrier (for example, the black photoconductor 20B in FIG. 19) is the same, so the work around the black photoconductor 20B is performed. A common image process can be used, and the first latent image carrier can be configured simply. In addition, it is not necessary to separately provide a mechanism for changing the rotation direction of the first latent image carrier or to perform separate control, and the entire apparatus can be configured simply.

  Next, the arrangement and functional characteristics of the constituent members of the image forming units 100 to 100e used in the color digital multifunction peripheral 1 described as the first to sixth embodiments are displayed in FIG.

  Regarding A (color (mode) transferred first to transfer paper), in the first, third, and fifth embodiments, black is transferred first. In this case, there is no problem that the color color adheres (reverse transfer) to the black photoreceptor 20B through the transfer paper P. In contrast, in the second, fourth, and sixth embodiments, full-color transfer is first. In this case, there is no problem that black color adheres (reverse transfer) to the intermediate transfer belt through the transfer paper P.

  Regarding B (the position of the black color on the intermediate transfer belt 11), in the second, fourth, and fifth embodiments, the black photosensitive member 20B is the most upstream, and in this case, the black photosensitive member 20B is transferred from the intermediate transfer belt 11 to the black photosensitive member 20B. Color color is not mixed. On the other hand, in the first, third, and fifth embodiments, the black photoconductor 20B is the most downstream, and in this case, the black color is not mixed into the color photoconductors (20Y, 20C, and 20M).

  Regarding C (black color transfer method in the monochrome mode), in the first and second embodiments, secondary transfer is performed via the intermediate transfer roller (second intermediate transfer member) 200. In this case, the black photosensitive member 20B is transferred. There is no problem of paper dust mixing. On the other hand, since the black color is directly transferred in the third to sixth embodiments, the transfer rate to the paper is improved by the amount not passing through the second intermediate transfer body 200, and a good monochrome image is obtained.

  Regarding D (position where the intermediate transfer roller (second intermediate transfer member) 200 is provided), in the first and second embodiments, the intermediate transfer roller (second intermediate transfer member) 200 is disposed between the photosensitive member 20B and the second transfer member 204. In the third and fourth embodiments, an intermediate transfer roller (second intermediate transfer member) 200 is provided between the photoconductor 20B and the intermediate transfer belt 11. In the fifth embodiment, an intermediate transfer roller (second intermediate transfer member) 200 is provided. Is provided between the first transfer member 66d and the photosensitive member 20B, and in the sixth embodiment, an intermediate transfer roller (second intermediate transfer member) 200 is provided between the first transfer member 66e and the photosensitive member 20B. Exhibits the transcription function.

  E (the rotation direction of the black photoconductor 20B in monochrome / full color) is the same in each of the first to sixth embodiments. For this reason, the configuration can be simplified in that there is no need for reverse rotation and that the image forming process can be made common regardless of the mode.

  The image forming unit 100 according to the first to sixth embodiments that can be employed in the color digital multifunction peripheral 1 has been described above. However, other image forming apparatuses that replace the color digital multifunction peripheral 1 also include the first to sixth embodiments. The image forming unit 100 of the embodiment can be applied in the same manner, and the same function and effect can be obtained.

1 Color digital multifunction device 8 Exposure device (optical unit)
DESCRIPTION OF SYMBOLS 10 Intermediate transfer unit 11-11e Intermediate transfer belt 57f-57fe Previous secondary transfer position 57r-57re Rear secondary transfer position 60Y, 60C, 60M, 60B Image forming unit 66-66e Rear transfer roller 99 Main body 100-100e Image formation Part 200-200e Intermediate transfer roller 201-201e First separation mechanism 202-202e Second separation mechanism 203-203e Third separation mechanism 204-204e Pre-transfer roller 500 Control unit m1 First state m2 Second state u1 Secondary transfer Position u2 Retraction position D1, D2 Separation distance P Recording paper P31 Primary transfer position (transfer position)
P32 Separation position R Conveyance path

JP 2002-182447 A JP 2006-251535 A JP 2006-85138 A JP 10-55094 A JP 2007-279624 A

Claims (14)

An image forming apparatus having a plurality of latent image carriers corresponding to respective colors, wherein a toner image visualized on the plurality of latent image carriers is primarily transferred, and then the toner image is secondarily transferred. A first state in which secondary transfer can be performed using a first transfer member as a recording material on a conveyance path at a position, and one latent image carrier among the plurality of latent image carriers and the first transfer member are separated from each other. A first intermediate transfer body that is switched between a second state and a third state in which the plurality of latent image carriers are brought into contact with each other at a primary transfer position and then separated from the first transfer body ; and the one latent image carrier A second intermediate transfer member that is switched to a position different from the first intermediate transfer member at a position opposite to the first intermediate transfer member and a position separated from the other transfer position, and a toner image of the second intermediate transfer member. A second transfer body that is switched to a position where the secondary transfer is performed and a position where the second transfer is separated from the same position; And a control means for changing in accordance with the position of the secondary transfer position and the second transfer body which is the primary transfer of the state and the second intermediate transfer member of the transfer body to the kind of image forming mode, a possess the When the image forming mode is the full color mode, the control means switches the first intermediate transfer member to the first state by the first separation mechanism, and the second intermediate transfer member to the third state by the second separation mechanism. Each of the first intermediate transfer members is switched to the second state by the first separation mechanism and the second intermediate transfer member is moved to the primary transfer position by the second separation mechanism. The second transfer body is switched to the secondary transfer position by the third separation mechanism, and further, when in the image adjustment pattern mode, the first intermediate transfer body is switched to the third state by the first separation mechanism. Image forming apparatus characterized by switching each disengaged position said second transfer member by the third separation mechanism by the second separation mechanism the second intermediate transfer member with. An image forming apparatus having a plurality of latent image carriers corresponding to each color, wherein a toner image visualized on the plurality of latent image carriers is primarily transferred at each primary transfer position and then the toner A first state in which an image can be secondarily transferred using a first transfer member as a recording material on a conveyance path at a secondary transfer position; and a primary transfer position of one of the plurality of latent image carriers. The first intermediate transfer is switched between a second state where the first transfer member is separated from the first transfer member and a third state where the second transfer member is brought into contact with the plurality of latent image carriers at a primary transfer position and then separated from the first transfer member. And a primary transfer feed state in which the toner image temporarily transferred from the latent image carrier prior to the primary transfer is primarily transferred to the first intermediate transfer member in the first state at the primary transfer position and the primary transfer state. A second intermediate transfer member that is switched from a transfer feed state to a released state; A second transfer body that is switched between a position at which toner images of one latent image carrier are primarily transferred to a recording material at a position different from the position of the second intermediate transfer body and a position at which the toner image is separated from the position; Control means for changing the state of the intermediate transfer member, the primary transfer feeding state of the second intermediate transfer member, and the primary transfer position of the second transfer member according to the type of image forming mode. When the image forming mode is the full color mode, the first intermediate transfer member is switched to the first state by the first separation mechanism, and the second intermediate transfer member is switched to the primary transfer feed state by the second separation mechanism. The second separation member is switched to the disengaged position by the three separation mechanism, and in the monochrome mode, the first intermediate transfer member is switched to the second state by the first separation mechanism and the second intermediate transfer member is separated by the second separation. The second transfer body is switched to a position for primary transfer by a third separation mechanism and the first intermediate transfer body is moved to the position for primary transfer by the third separation mechanism. The second intermediate transfer member is switched to the primary transfer feed state by the second separation mechanism and the second transfer member is switched to the separation position by the third separation mechanism. Image forming apparatus. An image forming apparatus having a plurality of latent image carriers corresponding to each color, wherein a toner image visualized on the plurality of latent image carriers is primarily transferred, and the toner image is temporarily secondary-transferred. A first intermediate transfer body that is switched at least between a first state that is transferred to a transfer position and a second state that is separated from one of the plurality of latent image carriers and the temporary secondary transfer position; The toner image, which has been temporarily secondary transferred at the temporary secondary transfer position prior to the secondary transfer from the first intermediate transfer body, is transferred to the secondary transfer position, and the first transfer body is used as a recording material on the conveyance path. A second intermediate transfer body that can be switched between a secondary feed transfer state in which secondary transfer is possible and a state in which the secondary transfer transfer state is released, and a toner image of the one latent image carrier are primarily transferred to a recording material. A second transfer body that is switched to a position separated from the same position, and the front Control means for changing the state of the first intermediate transfer member, the secondary feed transfer state of the second intermediate transfer member, and the primary transfer position of the second transfer member according to the type of image forming mode. When the image forming mode is the full color mode, the control unit switches the first intermediate transfer member to the first state by the first separation mechanism, and switches the second intermediate transfer member to the secondary feed transfer state by the second separation mechanism. At the same time, the second transfer body is switched from the primary transfer position by the third separation mechanism to the separation position, and in the monochrome mode, the first intermediate transfer body is switched to the second state by the first separation mechanism. The second intermediate transfer body is switched to the released state and the second transfer body is switched to a primary transfer position by a third separation mechanism. Further, when in the image adjustment pattern mode, And characterized in that one of the intermediate transfer member is switched to the first state by the first separating unit, switching the second intermediate transfer member to the disengaged position by the third separating mechanism of the second transfer body with switching to the state of the withdrawal Image forming apparatus. 4. The image forming apparatus according to claim 1, wherein a toner image is transferred onto the same surface of the recording material in the full color mode and the monochrome mode . 5. Image forming apparatus. The image forming apparatus according to any one of claims 1 to 4, wherein one of the latent image bearing member, an image forming apparatus, characterized in that in the same position as in the case of a full color mode and the monochrome mode . The image forming apparatus according to any one of claims 1 to 5, comprising an image detecting means provided opposite to the first intermediate transfer member, the image detection means, all of the plurality of latent image An image pattern transferred to the first intermediate transfer member after being visualized on the carrier is detected, and the positions of the image patterns transferred from the plurality of latent image carriers are aligned with each other. Image forming apparatus. 7. The image forming apparatus according to claim 1, wherein the first intermediate transfer member has an endless belt shape, and the second intermediate transfer member has a roller shape . The image forming apparatus according to any one of claims 1 to 7, the image forming apparatus, wherein the first transfer body and the second transfer member is a roller shape. 9. The image forming apparatus according to claim 1, wherein a latent image carrier having a closest distance to a recording material conveyance path among the plurality of latent image carriers is the one latent image carrier. an image forming apparatus characterized in that. The image forming apparatus according to any one of claims 1 to 5,
An image forming apparatus , wherein a position where a toner image is transferred to a recording material in a monochrome mode is upstream of a position where the toner image is transferred to the recording material in a full color mode . The image forming apparatus odor according to any one of claims 1 to 10 Te, the latent image bearing member, a charging means, cleaning means, image, characterized in that it comprises a process cartridge integrally holding a developing device Forming equipment. An image forming apparatus comprising a plurality of process cartridges according to claim 11 . 4. The image forming apparatus according to claim 2, wherein a toner image is transferred to the same side surface of the recording material in the first mode and the second mode . 14. The image forming apparatus according to claim 13 , wherein the rotation direction of the first latent image carrier is the same in the first mode and the second mode .

Images