JP4006942B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus such as a copying machine, a printer, or a facsimile capable of forming a full-color or black-and-white image using an electrophotographic system, and more specifically, forms toner images having different colors. A plurality of image forming units, and a belt-like intermediate transfer body for sequentially transferring a plurality of toner images of different colors from the plurality of image forming units is disposed above the plurality of image forming units. The present invention relates to an image forming apparatus.
[0002]
[Prior art]
Conventionally, as an apparatus capable of forming a color image at high speed and high image quality in an image forming apparatus such as a copying machine or a printer capable of forming a full-color or black-and-white image using the above-described electrophotographic method, Four image forming units that form toner images of different colors such as yellow, magenta, cyan, and black are arranged in parallel with each other, and yellow, magenta, cyan, and black are sequentially formed by these image forming units. The toner images of the respective colors are temporarily transferred onto the intermediate transfer belt once in a multiplex manner, and then secondary transferred collectively from the intermediate transfer belt onto the transfer paper, and the toner image is fixed on the transfer paper, Various so-called full-color tandem machines configured to form a color image have been proposed and have actually been commercialized.
[0003]
An example of such a full-color tandem machine is shown in FIG. As shown in FIG. 7, this full-color tandem machine includes four image forming units 100Y, 100M, 100C, and 100K that form toner images of different colors such as yellow, magenta, cyan, and black. The units 100Y, 100M, 100C, and 100K are arranged in parallel at a constant interval along the horizontal direction. The four image forming units 100Y, 100M, 100C, and 100K are configured in the same manner except that the color of the toner image to be formed is different, and the surface of the photosensitive drum 101 is uniformly formed by the contact-type charging device 102. Then, the exposure device 103 performs image exposure on the surface of the photosensitive drum 101 to form an electrostatic latent image corresponding to the image information of each color. The electrostatic latent image formed on the surface of the photosensitive drum 101 is visualized by a corresponding color developing device 104 to become a toner image, and the toner image is transferred to an intermediate transfer belt by a charger 105 for primary transfer. Multiple images are sequentially transferred onto the 106. The toner and paper dust remaining on the surface of the photosensitive drum 101 are removed by the cleaning device 107 to prepare for the next image forming process.
[0004]
The intermediate transfer belt 106 is disposed below the four image forming units 100Y, 100M, 100C, and 100K, and the rotation speed of the photosensitive drum 101 is determined by a plurality of rollers 108 to 112 including a driving roller. It is designed to circulate at an equal speed. The toner images of yellow, magenta, cyan, and black, which are sequentially transferred onto the intermediate transfer belt 106 in multiple layers, are transferred to the surface of the intermediate transfer belt 106 at the secondary transfer position provided below the intermediate transfer belt 106. Are transferred all at once onto a transfer sheet 114 fed at a predetermined timing by a secondary transfer roll 113 in contact with the sheet. Thereafter, the transfer sheet 114 is conveyed to a fixing device (not shown), subjected to a fixing process with heat and pressure by the fixing device, and discharged to the outside of the device to form a full-color or monochrome image.
[0005]
[Problems to be solved by the invention]
However, the conventional technique has the following problems. That is, the conventional image forming apparatus includes four image forming units 100Y, 100M, 100C, and 100K that form toner images of each color such as yellow, magenta, cyan, and black, as shown in FIG. The toner images of each color formed by the plurality of image forming units 100Y, 100M, 100C, and 100K are sequentially primary-transferred onto the intermediate transfer belt 106 and then collectively onto the transfer paper 114 from the intermediate transfer belt 106. Thus, full-color images and the like can be formed at a high speed.
[0006]
However, in the case of the conventional image forming apparatus, the intermediate transfer belt 106 is disposed below the four image forming units 100Y, 100M, 100C, and 100K, and the four image forming units 100Y, 100M, 100C, and 100K are disposed. Since the toner images of each color such as yellow, magenta, cyan and black are sequentially transferred onto the intermediate transfer belt 106 located below the toner image, the toner image is transferred from the intermediate transfer belt 106. The transfer sheet 114 is inevitably conveyed in the horizontal direction. For this reason, the fixing device that performs the fixing process on the transfer paper 114 must be disposed at a certain distance on the side of the intermediate transfer belt 106 in the horizontal direction, and the installation area in the horizontal direction of the image forming apparatus is limited. However, the size of the apparatus is increased, and it is difficult to reduce the size of the apparatus.
[0007]
Further, in the case of the conventional image forming apparatus, as described above, the transfer direction of the transfer sheet 114 is necessarily horizontal, so the discharge direction of the transfer sheet 114 is also necessarily horizontal. Therefore, it is necessary to provide a discharge tray or the like on the side surface of the main body of the image forming apparatus, and there is a problem that the installation area in the horizontal direction of the image forming apparatus becomes large and the apparatus becomes large.
[0008]
Further, in the case of the conventional image forming apparatus, as described above, the conveyance direction of the transfer paper 114 is inevitably horizontal, so that when forming a monochrome monochrome image, the black image forming unit 100K. Even if the intermediate transfer belt 106 does not rotate approximately half a circle, a monochrome single-color image cannot be transferred onto the transfer paper 114, even if it is disposed at the final stage (left end in FIG. 7). There was a problem that the productivity of monochromatic images could not be improved sufficiently.
[0009]
In particular, in recent years, with the rapid spread of personal computers and the like, the demand for full-color images has increased. However, there are not always many users who always perform full-color printing, and users who print monochrome images together. There are relatively many. As a result, in the above-described full-color image forming apparatus, even when a user prints a black and white image, it is required to form a black and white image at a speed at which a user accustomed to a conventional monochrome machine does not feel stress. Has been.
[0010]
Accordingly, the present invention has been made to solve the above-described problems of the prior art, and an object of the present invention is to provide an image forming apparatus capable of forming a full-color image at high speed. An object of the present invention is to provide an image forming apparatus that can be miniaturized.
[0011]
Another object of the present invention is that an image forming apparatus capable of forming a full-color image at a high speed can be greatly reduced in size, and monochrome images can be used only for conventional monochrome images. It is an object of the present invention to provide an image forming apparatus that can be formed with high productivity that is not inferior to that of a printing machine.
[0012]
[Means for Solving the Problems]
That is, according to the first aspect of the present invention, a plurality of image forming units that form toner images of different colors including black are arranged in parallel, and the plurality of images are formed over the plurality of image forming units. An image in which a belt-like intermediate transfer member to which toner images of respective colors formed by the forming units are transferred is arranged, and an image is written on the image carrier of each image forming unit below the plurality of image forming units. In the image forming apparatus in which the writing unit is arranged ,
The electrostatic latent images formed on the image carriers of the plurality of image forming units by driving the image carriers of the plurality of image forming units including the black by the driving means for the same image carrier. Among the developing means for developing the color toner image, a plurality of developing means for developing the color toner image are driven by the driving means for the same developing means, and the developing means for developing the black toner image is the main drive of the image forming apparatus. It is configured to be driven by means .
[0013]
According to a second aspect of the present invention, a transfer medium onto which a toner image is transferred from the belt-shaped intermediate transfer member is conveyed from the lower side to the upper side in the vertical direction, and transferred from the belt-like intermediate transfer member. Secondary transfer means for transferring the toner image onto the medium is provided on the side of the intermediate transfer belt.
[0014]
Further, according to a third aspect of the present invention, an image forming unit that forms a black toner image is disposed on the most downstream side in the moving direction of the belt-shaped intermediate transfer member among the plurality of image forming units. It is configured.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0017]
FIG. 2 shows a tandem digital color printer as an image forming apparatus according to an embodiment of the present invention. FIG. 3 shows a tandem type digital color copying machine as an image forming apparatus according to an embodiment of the present invention.
[0018]
2 and 3, reference numeral 1 denotes a main body of a tandem type digital color printer and copying machine. In the case of a digital color copying machine, as shown in FIG. An automatic document feeder (ADF) 3 that automatically conveys the documents one by one and a document reading device 4 that reads an image of the document 2 conveyed by the automatic document feeder 3 are provided. The document reader 4 illuminates a document 2 placed on a platen glass 5 with a light source 6, and reflects a reflected light image from the document 2 from a full-rate mirror 7, half-rate mirrors 8 and 9, and an imaging lens 10. The image reading element 11 composed of a CCD or the like is scanned and exposed through a reduction optical system, and the color material reflected light image of the document 2 is formed at a predetermined dot density (for example, 16 dots / mm) by the image reading element 11. It is supposed to read.
[0019]
The color material reflected light image of the document 2 read by the document reading device 4 is, for example, IPS (red (R), green (G), blue (B) (8 bits each) as document reflectance data of three colors. (Image Processing System) 12, and the IPS 12 performs predetermined corrections such as shading correction, position shift correction, brightness / color space conversion, gamma correction, frame deletion, color / moving editing, etc. on the reflectance data of the document 2. Image processing is performed. The IPS 12 also performs predetermined image processing on image data sent from a personal computer or the like.
[0020]
The image data that has been subjected to the predetermined image processing by the IPS 12 as described above is also four colors of yellow (Y), magenta (M), cyan (C), and black (K) (each 8 bits) by the IPS 12. As described below, the image forming units 13Y, 13M, 13C, and 13K for each color of yellow (Y), magenta (M), cyan (C), and black (K) are converted. The ROS (Raster Output Scanner) 14 is used, and the ROS 14 serving as the image exposure apparatus performs image exposure with the laser beam LB in accordance with document reproduction color material gradation data of a predetermined color.
[0021]
By the way, in the image forming apparatus according to this embodiment, a plurality of image forming units that form toner images of different colors are arranged in parallel, and the plurality of image forming units are formed over the plurality of image forming units. An image document in which a belt-like intermediate transfer member to which toner images of respective colors formed by the unit are transferred is arranged, and an image is written on the image carrier of each image forming unit below the plurality of image forming units. It is comprised so that an insertion means may be arrange | positioned.
[0022]
In this embodiment, the transfer medium on which the toner image is transferred from the belt-shaped intermediate transfer member is conveyed from the lower side to the upper side in the vertical direction, and the belt-like intermediate transfer member is transferred onto the transfer medium. Secondary transfer means for transferring the toner image is provided on the side of the intermediate transfer belt.
[0023]
Further, in this embodiment, an image forming unit for forming a black toner image is arranged on the most downstream side in the moving direction of the belt-shaped intermediate transfer member among the plurality of image forming units. ing.
[0024]
That is, inside the tandem type digital color printer and copying machine main body 1, as shown in FIGS. 1, 2, and 3, yellow (Y), magenta (M), cyan (C), black (K ) Four image forming units 13Y, 13M, 13C, and 13K are arranged in parallel at regular intervals in the horizontal direction.
[0025]
These four image forming units 13Y, 13M, 13C, and 13K are all configured in the same manner, and roughly divided, a photosensitive drum as an image carrier that is rotationally driven at a predetermined speed (for example, 200 mm / sec). 15, a charging roll 16 for primary charging that uniformly charges the surface of the photosensitive drum 15, and an image corresponding to a predetermined color is exposed on the surface of the photosensitive drum 15 to form an electrostatic latent image. ROS 14 as image exposure means, a developing unit 17 for developing the electrostatic latent image formed on the photosensitive drum 15 with toner of a predetermined color, and a cleaning device 18 for cleaning the surface of the photosensitive drum 15. It is configured. These photosensitive drums 15 and image forming members disposed in the periphery are integrally unitized, and are configured to be individually replaceable from the printer and the copying machine main body 1.
[0026]
As shown in FIGS. 2 and 3, the ROS 14 is configured in common to the four image forming units 13Y, 13M, 13C, and 13K, and uses four semiconductor lasers (not shown) to reproduce the color reproduction gradation material for each color. The laser beams LB-Y, LB-M, LB-C, and LB-K are emitted from these semiconductor lasers according to the gradation data. Of course, the ROS 14 may be individually configured for each of a plurality of image forming units. The laser beams LB-Y, LB-M, LB-C, and LB-K emitted from the semiconductor laser are irradiated to the polygon mirror 19 through an f-θ lens (not shown), and are deflected and scanned by the polygon mirror 19. The The laser beams LB-Y, LB-M, LB-C, and LB-K deflected and scanned by the polygon mirror 19 are exposed to exposure points on the photosensitive drum 15 through an imaging lens and a plurality of mirrors (not shown). Then, scanning exposure is performed obliquely from below.
[0027]
As shown in FIG. 2, the ROS 14 scans and exposes an image on the photosensitive drum 15 from below. Therefore, the ROS 14 includes four image forming units 13Y, 13M, 13C, and 13K located above. There is a possibility that toner or the like may fall from the developing unit 17 and be contaminated. Therefore, the periphery of the ROS 14 is hermetically sealed by a rectangular parallelepiped frame 20, and four laser beams LB-Y, LB-M, LB-C, and LB-K are placed on the upper portion of the frame 20, Transparent glass windows 21Y, 21M, 21C, and 21K as shield members are provided for exposure on the photosensitive drums 15 of the image forming units 13Y, 13M, 13C, and 13K.
[0028]
From the IPS 12, the image of each color is provided to the ROS 14 provided in common to the image forming units 13Y, 13M, 13C, and 13K of each color of yellow (Y), magenta (M), cyan (C), and black (K). Data is sequentially output, and the laser beams LB-Y, LB-M, LB-C, and LB-K emitted from the ROS 14 in accordance with the image data are scanned and exposed on the surface of the corresponding photosensitive drums 15 to statically. An electrostatic latent image is formed. The electrostatic latent images formed on the photosensitive drum 15 are respectively developed in yellow (Y), magenta (M), cyan (C), and black (K) colors by developing units 17Y, 17M, 17C, and 17K. Developed as a toner image.
[0029]
The yellow (Y), magenta (M), cyan (C), and black (K) toner images sequentially formed on the photosensitive drums 15 of the image forming units 13Y, 13M, 13C, and 13K are as follows. Multiplexed by four primary transfer rolls 26Y, 26M, 26C, and 26K on an intermediate transfer belt (belt-shaped intermediate transfer member) 25 of a transfer unit 22 disposed over the image forming units 13Y, 13M, 13C, and 13K. Is transcribed. These primary transfer rolls 26Y, 26M, 26C, and 26K are disposed on the back side of the intermediate transfer belt 25 corresponding to the photosensitive drums 15 of the image forming units 13Y, 13M, 13C, and 13K. The primary transfer rolls 26Y, 26M, 26C, and 26K in this embodiment use volume resistance values that have been adjusted to a resistance of 10 ⁵ to 10 ⁸ Ωcm. The primary transfer rolls 26Y, 26M, 26C, and 26K are connected to a transfer bias power source (not shown), and a transfer bias having a polarity opposite to a predetermined toner polarity (positive polarity in the present embodiment) is predetermined. It is applied at the timing.
[0030]
Further, as shown in FIG. 2, the intermediate transfer belt 25 is wound around the drive roll 27, the tension roll 24, and the backup roll 28 with a certain tension, and has excellent constant speed (not shown). The drive roll 27 is rotationally driven by a dedicated drive motor and is circulated at a predetermined speed in the direction of the arrow. FIG. 1 shows a case where the intermediate transfer belt 25 is supported by four rolls including an idler roll 24 b in addition to the drive roll 27, the tension roll 24 a, and the backup roll 28. The intermediate transfer belt 25 is made of, for example, a belt material (rubber or resin) that does not cause charge-up, and its volume resistance value is adjusted to a resistance of about 10 ⁵ to 10 ¹² Ωcm. Has been.
[0031]
As shown in FIG. 2, the toner images of yellow (Y), magenta (M), cyan (C), and black (K) transferred onto the intermediate transfer belt 25 are transferred to the intermediate transfer belt 25. The recording sheet is secondarily transferred onto a recording sheet 30 as a recording medium by a secondary transfer roll 29 that is pressed against the backup roll 28 disposed on the side surface of the recording sheet, and the toner images of these colors are transferred. 30 is conveyed to a fixing device 31 positioned above. The secondary transfer roll 29 is in pressure contact with the side of the backup roll 28, and secondary-transfers each color toner image onto a recording sheet 30 that is conveyed upward from below in the vertical direction. . The recording paper 30 onto which the toner images of the respective colors are transferred is subjected to a fixing process by heat and pressure by a fixing device 31 and then discharged onto a discharge tray 33 provided on the upper portion of the main body 1 by a discharge roll 32. The
[0032]
As shown in FIGS. 2 and 3, the recording paper 30 is of a predetermined size from a paper feeding device 34 disposed inside the apparatus main body 1 and is fed with a nudger roll 35 and a paper for separating and conveying the paper. The rolls 36 are once transported to a resist roll 38 provided in the paper transport path 37 in a state of being separated one by one and stopped. A conveyance path 37 of the fed recording paper 30 is directed upward in the vertical direction. The recording paper 30 supplied from the paper feeding device 34 is sent to the secondary transfer position of the intermediate transfer belt 35 by a registration roll 38 that rotates at a predetermined timing.
[0033]
In the above digital color printer and copying machine, when making a full-color double-sided copy, the recording paper 30 having an image fixed on one side is not directly discharged onto the discharge tray 33 by the discharge roll 32, but is shown in the figure. The conveyance direction is switched by the switching gate not to be conveyed, and the sheet is conveyed to the duplex conveyance unit 40 via the sheet conveyance roller pair 39. In the double-sided conveyance unit 40, the recording paper 30 is conveyed again to the registration roll 38 with the front and back sides of the recording paper 30 reversed by a pair of conveyance rollers (not shown) provided along the conveyance path 41. Is discharged onto the discharge tray 33 after the image is transferred and fixed on the back surface of the recording paper 30.
[0034]
2 and 3, 44Y, 44M, 44C, and 44K supply toners of predetermined colors to the developing devices 17 of yellow (Y), magenta (M), cyan (C), and black (K), respectively. Each toner cartridge is shown.
[0035]
FIG. 4 shows the image forming units of the digital color printer and the copying machine.
[0036]
The four image forming units 13Y, 13M, 13C, and 13K of yellow, magenta, cyan, and black are all configured similarly as shown in FIG. 4, and these four image forming units 13Y. , 13M, 13C, and 13K, as described above, yellow, magenta, cyan, and black toner images are sequentially formed at predetermined timings. As described above, the image forming units 13Y, 13M, 13C, and 13K for the respective colors are provided with the photosensitive drums 15, and the surfaces of these photosensitive drums 15 are uniformly formed by the charging rolls 16 for primary charging. Charged. Thereafter, the surface of the photosensitive drum 15 is scanned and exposed to an image forming laser beam LB emitted from the ROS 14 according to the image data, and an electrostatic latent image corresponding to each color is formed. The laser beam LB that is scanned and exposed on the photosensitive drum 15 is set so as to be exposed from an obliquely lower side slightly to the right of the photosensitive drum 15. The electrostatic latent image formed on the photosensitive drum 15 is converted into yellow, magenta, cyan, and black colors by the developing roll 17a of the developing unit 17 of each image forming unit 13Y, 13M, 13C, and 13K. The visible toner images are developed with toner, and these visible toner images are sequentially transferred in multiple onto the intermediate transfer belt 25 by the charging of the primary transfer roll 26.
[0037]
Residual toner, paper dust, and the like are removed from the surface of the photosensitive drum 15 after the toner image transfer process by the cleaning device 18 to prepare for the next image forming process. The cleaning device 18 includes a cleaning blade 42, and the cleaning blade 42 removes residual toner, paper dust, and the like on the photosensitive drum 15. Further, the surface of the intermediate transfer belt 25 after the toner image transfer process is finished, as shown in FIGS. 2 and 3, the residual toner and paper dust are removed by the cleaning device 43, and the next image forming process. Prepare for. The cleaning device 43 includes a cleaning brush 43a and a cleaning blade 43b. The cleaning brush 43a and the blade 42 remove residual toner, paper dust, and the like on the intermediate transfer belt 25.
[0038]
Further, in this embodiment, each image carrier of the plurality of image forming units is driven by the same driving means, and an electrostatic latent image formed on each image carrier of the plurality of image forming units is converted into an electrostatic latent image. Among the developing means for developing, a plurality of developing means for developing a color toner image are driven by the same driving means, and the developing means for developing a black toner image are driven by different driving means. ing.
[0039]
That is, in this embodiment, as shown in FIGS. 5 and 6, the photosensitive drums 15Y, 15M, 15C, and 15K of the image forming units 13Y, 13M, 13C, and 13K are connected by a common photosensitive member driving motor 51. The photosensitive member drive motor 51 is configured to be driven by a control circuit 50 including a CPU.
[0040]
Further, in this embodiment, as shown in FIGS. 5 and 6, among the image forming units 13Y, 13M, 13C, and 13K, each of the colors yellow (Y), magenta (M), and cyan (C) is selected. The developing machines 17Y, 17M, and 17C are configured to be driven by a common developing machine drive motor 52. The developing machine drive motor 52 is controlled by a control circuit 50 including a CPU and the like.
[0041]
Further, the black developing machine 17K is configured to be rotationally driven through a clutch 54 by a main motor 53 that drives a paper feed system and the like. The main motor 53 drives a paper feed system / conveyance system 56 such as a registration roll 38, a feed roll 36, or a nudger roll 35 through a clutch 55, and directly drives the fixing device 31 and the secondary transfer roll 29. It is configured to drive. The main motor 53 is controlled by a control circuit 50 including a CPU.
[0042]
The intermediate transfer belt 25 is configured to be rotationally driven by an intermediate transfer member drive motor 57 provided independently. The intermediate transfer member drive motor 57 is also controlled by a control circuit 50 including a CPU. It has become so.
[0043]
With the above configuration, in the printer and the copying machine according to this embodiment, the image forming apparatus capable of forming a full-color image at high speed can be significantly downsized as follows. It has become.
[0044]
Further, in the printer and the copying machine according to this embodiment, the apparatus can be greatly reduced in the following manner, and the monochrome image is inferior to the conventional monochrome machine. It is possible to form with high productivity.
[0045]
That is, in the printer and the copier according to this embodiment, as shown in FIGS. 1 and 2, each of the image forming units 13Y for yellow (Y), magenta (M), cyan (C), and black (K), Since the intermediate transfer belt 25 to which the toner images of the respective colors are transferred from the image forming units 13Y, 13M, 13C, and 13K is disposed above the 13M, 13C, and 13K, the toner images of the respective colors are transferred from the intermediate transfer belt 25. The conveyance direction of the recording paper 30 that is secondarily transferred collectively can be changed to the vertical direction instead of the horizontal direction as in the prior art, and the toner images of the respective colors are collectively output from the intermediate transfer belt 25 to the secondary direction. A fixing device 31 that performs a fixing process on the transferred recording paper 30 can be disposed above the intermediate transfer belt 25. Therefore, as in a conventional tandem type image forming apparatus, the conveyance direction of the recording paper is set to the horizontal direction, and the fixing is performed on the recording paper on which each color toner image is transferred from the intermediate transfer belt. The size of the image forming apparatus as a printer or a copying machine is reduced to a size substantially equal to the installation area of the intermediate transfer belt 25 because there is no need to install the device separately from the side of the intermediate transfer belt. It becomes possible to do.
[0046]
In the printer and the copying machine according to this embodiment, as shown in FIGS. 1 and 2, the image forming unit 13 </ b> K that forms a black toner image is placed at the final stage along the moving direction of the intermediate transfer belt 25. Therefore, when forming a black and white image, the toner image formed by the black image forming unit 13K is primarily transferred onto the intermediate transfer belt 25 and then recorded from the intermediate transfer belt 25. Since the secondary transfer can be immediately performed on the paper 30, the moving distance of the toner image when forming a black and white image is almost the same as that of a conventional monochrome machine, and the first black and white image can be transferred in a short time. In addition to being able to output, continuous productivity of black and white images can be obtained as high as that which is not inferior to that of conventional monochrome machines.
[0047]
Further, in the printer and the copying machine according to this embodiment, as shown in FIGS. 1 and 2, the developing device 17K of the black image forming unit 13K forms each of yellow, magenta, and cyan for forming other color images. Since the image forming units 13Y, 13M, and 13C are configured to be driven by a developing device drive motor 52 different from the developing devices 17Y, 17M, and 17C, when forming a black and white image, the color developing devices 17Y, Since it is not necessary to drive 17M and 17C, it is possible to prevent the developer of the color developing machines 17Y, 17M and 17C from being deteriorated.
[0048]
Furthermore, in the printer and the copier according to this embodiment, as shown in FIGS. 5 and 6, each image forming unit 13Y of yellow (Y), magenta (M), cyan (C), and black (K) is formed. , 13M, 13C, and 13K are configured to be driven by a common photoconductor drive motor 51. Therefore, a photoconductor drive motor is provided for each image forming unit. It is not necessary to reduce the cost of the apparatus, and it is possible to form a monochrome image by driving all the photosensitive drums 15Y, 15M, 15C, and 15K even when a monochrome image is formed. Sometimes, the color photoconductor drums 15Y, 15M, 15C and the color photoconductor drums 15Y, 15M, 15C During the transfer belt 25 and is rubbed, the color of the photosensitive drums 15Y, 15M, there is also an effect that the surface of the 15C can be reliably prevented from uneven wear.
[0049]
【The invention's effect】
As described above, according to the present invention, it is possible to provide an image forming apparatus capable of significantly reducing the size of the image forming apparatus capable of forming a full-color image at high speed.
[0050]
In addition, according to the present invention, in an image forming apparatus capable of forming a full-color image at high speed, the apparatus can be greatly reduced in size. It is possible to provide an image forming apparatus that can be formed with high productivity that is not so inferior.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing a digital color printer as an image forming apparatus according to an embodiment of the present invention.
FIG. 2 is a block diagram showing a digital color printer as an image forming apparatus according to an embodiment of the present invention.
FIG. 3 is a block diagram showing a digital color copying machine as an image forming apparatus to which a paper feeding device according to an embodiment of the present invention is applied.
FIG. 4 is a block diagram showing an image forming unit of the image forming apparatus according to the embodiment of the present invention.
FIG. 5 is a block diagram showing a drive system of the image forming apparatus according to an embodiment of the present invention.
FIG. 6 is a block diagram showing a drive system of the image forming apparatus according to the embodiment of the present invention.
FIG. 7 is a block diagram showing a conventional image forming apparatus.
[Explanation of symbols]
1: Digital color printer main body, 13Y, 13M, 13C, 13K: Image forming unit for each color of yellow (Y), magenta (M), cyan (C), black (K), 14: ROS, 15: photosensitive drum , 17: developing device, 25: intermediate transfer belt (belt-shaped intermediate transfer member), 29: secondary transfer roll, 30: recording paper, 31: fixing device.

Claims (3)

A plurality of image forming units for forming toner images of different colors including black are arranged in parallel, and the toner images of the respective colors formed by the plurality of image forming units are provided over the plurality of image forming units. In the image forming apparatus, the belt-shaped intermediate transfer member to be transferred is disposed, and further, an image writing unit for writing an image on the image carrier of each image forming unit is disposed below the plurality of image forming units .
The electrostatic latent images formed on the image carriers of the plurality of image forming units by driving the image carriers of the plurality of image forming units including the black by the driving unit for the same image carrier. Among the developing means for developing the color toner image, a plurality of developing means for developing a color toner image are driven by the driving means for the same developing means, and the developing means for developing the black toner image is a main drive of the image forming apparatus. An image forming apparatus driven by means . Secondary transfer in which a transfer medium on which a toner image is transferred from the belt-shaped intermediate transfer member is conveyed from the lower side to the upper side in the vertical direction, and the toner image is transferred from the belt-like intermediate transfer member onto the transfer medium. 2. The image forming apparatus according to claim 1, wherein the means is provided on a side of the intermediate transfer belt. The image forming unit for forming a black toner image is disposed on the most downstream side in the moving direction of the belt-shaped intermediate transfer member among the plurality of image forming units. Image forming apparatus.

Images