JP3455672B2 - Image forming device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus configured to apply a lubricant to the peripheral surface of an image bearing member such as a photosensitive drum.

[0002]

2. Description of the Related Art In copying machines, printers, and facsimile machines, an electrostatic latent image is formed on a photosensitive drum, and this is visualized as a toner image by a developing device. The toner image formed on the photosensitive drum is directly transferred to a sheet that has been conveyed, or is once transferred to an intermediate transfer member such as a transfer belt. At the time of this transfer, a predetermined voltage having a polarity opposite to that of the toner is applied to a transfer charger or a transfer roller provided on the back side of the paper or the transfer belt to attract the toner for transfer.

Toner may still remain on the peripheral surface of the photosensitive drum even after passing through the transfer portion. A cleaning device is provided to remove such residual toner. For example, a cleaning device uses a fur brush in which fibers are planted on the peripheral surface of the photosensitive drum and driven to rotate in order to weaken the binding force of the toner adhering to the peripheral surface of the photosensitive drum. The cleaning blade may be provided so as to be in contact with the peripheral surface of the photosensitive drum, and the cleaning blade may scrape off the toner on the peripheral surface of the photosensitive drum loosened by the fur brush.

In the case where such a cleaning device is provided, the cleaning blade is pressed against the peripheral surface of the photosensitive drum, and the toner and the paper powder that have become agglomerate adhere to the cleaning blade, and the cleaning blade and the photosensitive drum. The frictional resistance with the peripheral surface may increase. Therefore, it is conceivable to apply zinc stearate to the peripheral surface of the photosensitive drum with a fur brush to reduce the frictional resistance between the cleaning blade and the peripheral surface of the photosensitive drum. Further, it is effective to apply zinc stearate to the peripheral surface of the photoconductor drum in order to prevent the occurrence of "middle-out" in the image.

However, since the fur brush is always in contact with the peripheral surface of the photosensitive drum, zinc stearate is always applied to the peripheral surface when the photosensitive drum is rotationally driven. The developing device includes a developing roller arranged to face the photosensitive drum. A magnetic brush of toner is formed on the peripheral surface of the developing roller, and during development, the magnetic brush rubs the peripheral surface of the photosensitive drum, and an uncharged portion of the electrostatic latent image on the peripheral surface of the photosensitive drum. Toner adheres to the. From this, the electrostatic latent image on the peripheral surface of the photosensitive drum is visualized. Therefore, while the developing device is being driven, the magnetic brush of toner formed on the peripheral surface of the developing roller contacts the peripheral surface of the photoconductor drum, and even if excess zinc stearate is applied, it does not bind to the toner. And collected in the developing device.

[0006]

However, when the photosensitive drum is rotationally driven while the developing device is not driven, the zinc stearate applied to the surface of the photosensitive drum is not collected by the developing roller, so that the surface of the photosensitive drum is not recovered. The excess zinc stearate remains applied. When the image forming operation is performed in such a state, the charge amount of the toner changes and so-called "fog" occurs.

In an image forming apparatus such as a full-color copying machine, a plurality of developing devices in which toners of respective colors are stored based on color components forming a color image are arranged around a photosensitive drum, and an intermediate transfer member such as a transfer belt is arranged. There is an arrangement in which is opposed to the peripheral surface of the photosensitive drum. In this case, the toner image visualized on the photosensitive drum by one developing device is transferred onto the transfer belt, and the toner images formed by the other developing devices are sequentially transferred thereon in a laminated state. ,
A primary transfer process of forming a color toner image on the transfer belt is performed. After that, a secondary transfer step of transferring the color toner image on the transfer belt onto the conveyed paper is performed.

In the color copying machine thus constructed, zinc stearate is applied to the surface of the transfer belt in the secondary transfer process so that the toner is easily separated from the transfer belt to ensure the transfer onto the paper. For this purpose, a release agent applying means is provided. This release agent applying means can be provided, for example, with a sponge roller impregnated with zinc stearate so as to be capable of advancing and retreating with respect to the transfer belt surface so that the peripheral surface thereof can contact the transfer belt surface. Since zinc stearate is not applied to the transfer belt in the primary transfer step, the sponge roller is retracted to a position away from the transfer belt surface. The application of zinc stearate to the transfer belt is performed every time a predetermined number of secondary transfer steps are performed. For example, the number of sheets to be transferred is counted, and when the count value reaches a predetermined number, the sponge roller is brought into contact with the surface of the transfer belt, the transfer belt is rotationally driven, and zinc stearate is applied from the sponge roller. Can be configured to do.

At this time, when the transfer belt is rotationally driven,
At the same time, the photosensitive drum is also driven to rotate. When zinc stearate is applied to the transfer belt, zinc stearate is simultaneously applied to the peripheral surface of the photosensitive drum. However, when applying zinc stearate onto the transfer belt, the developing device is not driven unlike the rotational driving during image formation. Therefore, the zinc stearate applied to the peripheral surface of the photosensitive drum is not removed by the magnetic brush of the toner,
It will remain in the state that it was applied excessively. In this case, as described above, the charge amount of the toner changes, and the toner image formed has troubles such as fogging.

An object of the present invention is to remove an excessive amount of lubricant such as zinc stearate on an image bearing member such as a photosensitive drum with a simple structure and in a short time. An image forming apparatus is provided.

[0011]

[0012]

[0013]

[0014]

According to the present invention, there is provided an image forming apparatus including a photosensitive drum, a developing means, a transfer belt, a primary transfer means, a lubricant applying means, and a lubricant removing means. To do. Here, an electrostatic latent image is formed on the peripheral surface of the photosensitive drum. The developing means is composed of a plurality of developing devices in which color toners based on the color components forming the color image are stored, and visualizes the electrostatic latent image on the peripheral surface of the photosensitive drum into a toner image. The transfer belt is stretched between a driving roller and a driven roller, and is rotationally driven together with the photosensitive drum to transfer the toner images of the respective color toners visualized on the peripheral surface of the photosensitive drum in a laminated state. The primary transfer means transfers the toner image from the peripheral surface of the photosensitive drum to the intermediate transfer body. The lubricant applying means applies a lubricant to the peripheral surface of the photosensitive drum when the photosensitive drum and the transfer belt are rotationally driven. The lubricant removing unit drives any one of the plurality of developing devices to remove the excess lubricant applied to the peripheral surface of the photosensitive drum.

In such a structure, when the toner image is not formed by the developing means, the transfer belt may be rotationally driven and the lubricant may be applied to the peripheral surface of the photosensitive drum at the same time. In this case, extra lubricant is applied to the peripheral surface of the photosensitive drum. Therefore,
By removing such an excessive lubricant by the lubricant removing means, the formed image is not affected.

At this point, the transfer sheet is transferred onto the surface of the conveyed paper.
It can be from belt surface further comprises constituting a secondary transfer means for transferring the toner image. Further, it is possible to further comprise a release agent applying means for applying a toner release agent for promoting the transfer of the toner at the time of the secondary transfer to the transfer belt surface. In this case, the number of executions of the secondary transfer operation is counted. Further comprising a transfer number counting means, when the count value by the transfer number counting means reaches a predetermined value, the release agent applying means applies the toner release agent to the transfer belt,
Further, at this time, the lubricant applied to the peripheral surface of the photoconductor drum may be removed by the lubricant removing means.

In this case, when the toner releasing agent is applied to the transfer belt, the photosensitive drum is simultaneously driven to rotate,
Extra lubricant is applied to the peripheral surface of the photosensitive drum. However, it is possible to remove this excess lubricant by the lubricant removing means .

Further, the lubricant may be zinc stearate. Further, the lubricant removing means can be configured to drive any one of the plurality of developing devices to remove the excess lubricant on the peripheral surface of the photosensitive drum, and the developing means can be used for cyan, magenta, and yellow. If the black developing device is used, the lubricant removing means is configured to remove the lubricant excessively applied to the peripheral surface of the photoconductor drum by driving the black developing device. It is preferable.

The toner release agent is preferably zinc stearate.

[0020]

1 is a cross-sectional view of a full-color copying machine to which an embodiment of the present invention is applied. The copying machine 1 has a main body 10 and a document holder 11 mounted on the top of the main body 10 so as to be openable and closable. A document table 15 on which a document is placed is arranged at the upper part of the main body 10. Inside the main body 10, an image forming unit 16 is provided at an end portion on the left side when viewed from the front and substantially at the center in the vertical direction. Further, a paper feed unit 17 for feeding a document to the image forming unit 16 is provided in the lower portion.

The paper feed unit 17 is detachably attached to the main body 10 and holds paper feed cassettes 18, 19 for storing paper.
20 and 21, and a bypass tray 22 provided on the right side thereof. Below the document table 15, the document table 1
An optical system 23 for reading the image information of the document placed on the sheet 5 is provided. The optical system 23 is a light source 24 for irradiating the surface of a document placed on the document table 15 with light.
And a mirror 2 for deflecting the light reflected from the document surface.
5, 26, 27, a lens 28 for converging the light from the mirror 27, a color image pickup device such as a CCD sensor for receiving the light converged by the lens 28 and generating an image data signal corresponding to an original image. 29 and 29.

The image forming section 16 has a photosensitive drum 30 on the surface of which an electrostatic latent image is formed, and further the photosensitive drum 3
0, the main charging device 31, the developing device 33,
It has 34, 35, 36, a transfer device 37 and a cleaning device 38. The main charging device 31 is a device for charging the surface of the photosensitive drum 30, and is arranged above the photosensitive drum 30. Developing devices 33, 34, 35, 36 for forming a toner image on the photoconductor drum 30 are arranged from the left side to the bottom of the photoconductor drum 30 with a predetermined gap from the main charging device 31. Each of the developing devices 33, 34, 35, and 36 stores cyan, magenta, yellow, and black toners, respectively, and visualizes the electrostatic latent image formed on the photosensitive drum 30 with each color toner. . The transfer device 37 is a device for transferring the toner image on the photoconductor drum 30 onto a sheet, and is arranged diagonally below and to the right of the photoconductor drum 30.
The cleaning device 38 is a device for removing residual toner and the like on the surface of the photoconductor drum 30, and is arranged obliquely above and to the right of the photoconductor drum 30.

An exposure device 39 for forming an electrostatic latent image on the peripheral surface of the photosensitive drum 30 is provided diagonally above and to the left of the photosensitive drum 30. The exposure device 39 includes a laser unit 40 and a mirror 41 that deflects the laser light from the laser unit 40 to the peripheral surface of the photosensitive drum 30, and the peripheral portion of the photosensitive drum 30 is rotated based on an image data signal obtained from the color image pickup device 29. An electrostatic latent image is formed on the surface. The laser light emitted from the exposure device 39 passes between the main charging device 31 and the developing device 33 and is applied to the peripheral surface of the photosensitive drum 30. [Transfer Device] As shown in FIG. 2, the transfer device 37 includes a drive roller 44 to which the drive force of the drive motor 42 is transmitted via the drive belt 43, a secondary transfer upper roller 45, and drive rollers 44 and 2. A transfer belt 46 stretched between the next transfer upper rollers 45, a primary transfer upper roller 47 that presses the outer peripheral surface of the transfer belt 46 against the peripheral surface of the photosensitive drum 30, a primary transfer lower roller 48, and a transfer. The tension roller 49 is provided on the inner peripheral surface side of the belt 46.

The primary transfer upper roller 47 and the primary transfer lower roller 48 are between the driving roller 44 and the secondary transfer upper roller 45, and the photosensitive drum 30 is provided via the transfer belt 46.
It is located at a position facing. Primary transfer upper roller 4
7 is movable between the primary transfer lower roller 48 and the pressing position where the transfer belt 46 is pressed against the peripheral surface of the photosensitive drum 30 and the separated position where the transfer belt 46 is separated from the peripheral surface of the photosensitive drum 30. ing.

For example, as shown in FIG. 3, the primary transfer roller 47 is rotatably mounted on a mounting plate 50,
The mounting plate 50 is rotatably mounted on the transfer device 37 via a support shaft 51. The mounting plate 50 has a projecting piece 52 projecting downward, and the projecting piece 52 has a primary pressing roller 53 provided in parallel with the rotation axis of the primary transfer upper roller 47.
Is provided. Also. The mounting plate 50 is biased by a spring 54 'in a direction away from the peripheral surface of the photosensitive drum 30.

On the transfer device 37 side, the primary pressing cam 5 having a cam surface capable of contacting the primary pressing roller 53 of the mounting plate 50.
4 is movably supported and provided. The driving force of the primary pressing cam drive motor 56 is transmitted to the primary pressing cam 54 by the driving belt 55, and the primary pressing cam 54 is rotatable. A light shielding plate 57 that rotates integrally with the primary pressing cam 54 is provided on the rotation shaft of the primary pressing cam 54. The light shielding plate 57 has a fan shape in which a part of a circular plate is cut out, and is arranged so as to be able to block the optical path of the transfer belt pressing sensor 58 composed of a photo interrupter.

For example, when the distance for pressing the primary pressing roller 53 on the cam surface of the primary pressing cam 54 is maximum, the primary transfer upper roller 47 presses the transfer belt 46 against the peripheral surface of the photosensitive drum 30. At the same time, the transfer belt pressing sensor 58 is shielded from light by the light shielding plate 57 and is turned on. Further, when the distance for pressing the primary pressing roller 53 on the cam surface of the primary pressing cam 54 is the minimum, the primary transfer upper roller 47 is located at the separated position for separating the transfer belt 46 from the peripheral surface of the photosensitive drum 30. At the same time,
The transfer belt pressing sensor 58 is released by the light shielding plate 57 and is turned off.

The transfer device 37 is provided with a zinc stearate coating device 59 for coating the transfer belt 46 with zinc stearate. The zinc stearate coating device 59 includes a zinc stearate coating brush 60 that is in pressure contact with the driving roller 44 via the transfer belt 46, and a zinc stearate storage unit 61 for supplying zinc stearate to the zinc stearate coating brush 60. It consists of and. The zinc stearate applying device 59 is used for the transfer belt 46.
When the toner attached to the paper is transferred to the surface of the paper, the binding force of the toner to the transfer belt 46 is weakened, and zinc stearate for preventing the hollowing of the toner image formed on the paper is transferred at regular intervals. 46 is applied to the surface. For this reason, the zinc stearate coating brush 60 is capable of projecting and retracting with respect to the transfer belt 46, and is pressed against the drive roller 44 as necessary to apply zinc stearate to the transfer belt 46. ing.

Further, the transfer belt 37 is attached to the transfer device 37.
Cleaning device 6 for cleaning the surface of 6
Two are provided. This cleaning device 62 is
Is disposed between the next lower transfer roller 48 and the secondary transfer on the roller 45, a cleaning roller 63 in contact with the inner peripheral surface of the transfer belt 46, a cleaning blade 64, the toner scraped off by the cleaning blade 64 And a toner recovery unit 66 having a spiral 65 for sending to a recovery tank.

The transfer device 37 includes a transfer belt 46.
A secondary transfer lower roller 67, which is disposed at a position facing the secondary transfer upper roller 45 via the transfer belt 46, applies a voltage having a polarity opposite to that of the toner on the surface of the transfer belt 46 to transfer the toner image onto the sheet. There is. The secondary transfer lower roller 67 is shown in FIG.
As shown in, it is rotatably supported by the mounting plate 68. Further, the secondary transfer lower roller 67 is provided with secondary pressing rollers 69 having a slightly larger outer diameter and rotating integrally with each other at both ends in the width direction. When the outer peripheral surface of the secondary pressing roller 69 contacts the side plate of the transfer device 37,
Positioning is performed so that the peripheral surface of the secondary transfer lower roller 67 and the surface of the transfer belt 46 are at a constant distance.

The mounting plate 68 is movable in the vertical direction in FIG. 4, and is biased downward by a biasing member (not shown) such as a spring. Further, the mounting plate 68 has a protruding piece 70 protruding downward. The projecting piece 70 is provided with a contact piece 71 that is projected in parallel with the rotation axis of the secondary transfer lower roller 67. The contact piece 71 can come into contact with the cam surface of the secondary pressing cam 72 rotatably supported by the side plate of the transfer device 37. The secondary pressing cam 72 is rotatable by a drive motor (not shown) and includes a light shielding plate 73 that rotates integrally. The light shielding plate 73 is configured so as to be capable of taking a position where the optical path of the transfer roller pressing sensor 74 constituted by a photo interrupter is blocked and a position where it is opened by rotating.

For example, when the contact piece 71 moved by the cam surface of the secondary pressing cam 72 is located at the uppermost position,
The mounting plate 68 is pushed up to the highest. At this time, 2
The next pressing roller 69 comes into contact with the side plate of the transfer device 37 to position the secondary transfer lower roller 67 at a predetermined position, and the light blocking plate 73 blocks the optical path of the transfer roller pressing sensor 74 to turn it on. When the contact piece 71 moved by the cam surface of the secondary pressing cam 72 is located at the lowest position,
The mounting plate 68 is positioned at the lowest position by the urging of the urging member. At this time, the secondary transfer lower roller 67 is separated from the surface of the transfer belt 46, and at the same time, the light shielding plate 73 opens the optical path of the transfer roller pressing sensor 74 to turn it off.

Further, the secondary transfer lower roller 67 is provided with a cleaning blade 75 for peeling off the toner adhering to the peripheral surface in a state of being pressed against the peripheral surface. further,
A separation needle 7 for separating a sheet from the transfer belt 46 by applying a predetermined voltage in the vicinity of the secondary transfer lower roller 67.
6 is provided. [Paper Feed Unit] The paper feed unit 17 includes the paper feed cassettes 18 and 1.
A vertical transport path 81 for transporting paper from 9, 20, and 21 toward the image forming unit 16 and a bypass transport path 82 for transporting paper from the bypass tray 22 toward the image forming unit 16 are provided. Each paper feed cassette 18, 19, 20,
21 and the bypass tray 22 have pickup rollers 83, 84, 8 for taking out stored sheets.
5, 86, 87 and paper feed roller pairs 88, 89, 90, 91, 92 for feeding the paper one by one to the conveying path are provided. The vertical transport path 81 has a pair of transport rollers 93,
94, 95, 96 are provided. The vertical transport path 81 and the bypass transport path 82 are joined on the right side of the secondary transfer upper roller 45 and the secondary transfer lower roller 67 of the transfer device 37, and a paper feed transport path 97 for supplying a sheet to the transfer device 37.
In succession. The sheet feeding / transporting path 97 is provided with registration rollers 98 for holding the sheet transported from the sheet feeding section 17 at a predetermined position. [Fixing Device] On the left side of the secondary transfer upper roller 45 and the secondary transfer lower roller 67 of the transfer device 37, a paper discharge transport path 99 for transporting the paper on which the toner image is transferred is formed. Further, the fixing device 100 is arranged on the left side. The fixing device 100 includes a heating roller 101 having a built-in heater and a pressure roller 10 that is in pressure contact with the heating roller 101.
2 is provided to sandwich and convey the paper between both rollers and heat and fix the toner image formed on the paper surface.

A paper discharge roller pair 103 is provided on the further left side of the fixing device 100, and is configured to discharge the paper to a paper discharge tray 104. [Transfer Belt] The transfer belt 46 is made of a fluororesin or the like, and as shown in FIG. 5, an outer peripheral surface 111 to which a toner image is transferred and an intermediate inner peripheral surface supported by the outer peripheral surfaces of the rollers. It has 112. At both edges of the transfer belt 46 in the width direction, meandering prevention ridges 11 protruding toward the inner peripheral surface side are formed.
3,113 are provided. This meandering prevention ridge 11
Reference numerals 3 and 113 have end inner peripheral surfaces 114 and 114 that contact the outer peripheral surfaces of the end edges of the rollers.

Each roller on which the transfer belt 46 is stretched has a structure as shown in FIG. 5, and here the primary transfer upper roller 47 is shown as an example. Primary transfer upper roller 4
Reference numeral 7 denotes an intermediate support portion 115 that supports the intermediate inner peripheral surface 112 of the transfer belt 46, and an edge support portion 116 that has a diameter smaller than that of the intermediate support portion 115 by the height of the meandering prevention protrusion 113. have. The outer peripheral surface of the intermediate support portion 115 has a width substantially the same as the width of the intermediate inner peripheral surface 112 of the transfer belt 46, and contacts the intermediate inner peripheral surface 112 to support the intermediate inner peripheral surface 112 of the transfer belt 46. Intermediate support surface 1
Make up 17. The end edge support portions 116 are provided at both end edges of the intermediate support portion 115, and the outer peripheral surfaces thereof have a width substantially the same as the width of the meandering prevention ridges 113 of the transfer belt 46. End inner peripheral surface 114 of the strip 113
Constitutes an end support surface 118 for supporting.

As a result, as shown in FIG. 6, the intermediate inner peripheral surface 112 of the transfer belt 46 has the primary transfer upper roller 47.
Of the primary transfer roller 47 by contacting the inner peripheral surface 114 of the end portion of the meandering prevention protrusion 113 with the end support surface 118 of the primary transfer upper roller 47. It is supported on the outer peripheral surface. Each of the primary transfer lower roller 48, the cleaning roller 63, the secondary transfer upper roller 45, the tension roller 49, and the drive roller 44 has an intermediate support portion and an edge support portion, like the primary transfer upper roller 47 described above. It is configured to have and. As a result, the transfer belt 46 comes into contact with and uniformly supports the outer peripheral surface of each roller at the widthwise intermediate portion and the widthwise end portion, and thus the outer peripheral surface does not have irregularities. Particularly, in the primary transfer portion, since the primary transfer upper roller 47 and the primary transfer lower roller 48 are arranged relatively close to each other, the inner peripheral surface of the meandering preventing protrusion 113 is separated from the outer peripheral surface of the roller. In that case, a dent is likely to occur at the end edge portion between both rollers, but in the above-described embodiment, such a problem is ameliorated, and it is possible to prevent the toner image to be transferred from missing.

A detection hole 120 is formed at the end of the transfer belt 46 in the width direction so as to penetrate both sides. The detection holes 120 are provided at six locations at equal intervals in the rotation direction of the transfer belt 46, and are used to position the tip of the toner image formed on the outer peripheral surface 111. Transfer device 37
As shown in FIG. 2, a photo interrupter 122 is attached to the frame of FIG.
As shown in FIG. 7, the photo interrupter 122 is L
The light emitting portion 123 formed of the ED and the light receiving portion 124 formed of a phototransistor are arranged so as to face each other with a predetermined distance therebetween, and the light emitting portion 123 and the light receiving portion 124 are the widthwise edges of the transfer belt 46. It is arranged so as to sandwich the section. The light emitted from the light emitting unit 123 of the photo interrupter 122 is blocked by the transfer belt 46 and is received by the light receiving unit 124.
If not reached, the photo interrupter 122
Does not output a detection signal. As the transfer belt 46 rotates, the detection hole 12 is formed at the position of the photo interrupter 122.
When 0 arrives, the light from the light emitting unit 123 receives light from the light receiving unit 124.
The photo interrupter 122 generates a detection signal. Based on the detection signal output from the photo interrupter 122, a timing signal for performing the transfer operation is generated to perform the primary transfer of the toner image from the photosensitive drum 30 to the transfer belt 46 or the toner image from the transfer belt 46 to the paper. Second transfer is performed.

At this time, the detection holes 120 provided at the widthwise edge of the transfer belt 46 are provided at six positions at equal intervals in the rotation direction, and the photo interrupter 122 detects which detection hole 120. A transfer timing signal can be generated even at the timing, and the standby time can be shortened and the processing time can be shortened. [Cleaning Device] As shown in FIG. 2, the cleaning device 38 includes a casing 141 arranged near the peripheral surface of the photosensitive drum 30.
A fur brush 142 rotatably supported by the casing 141, and a cleaning blade 143 pressed against the peripheral surface of the photosensitive drum 30. The fur brush 142 is a roller in which fibers are planted on the peripheral surface,
In order to weaken the binding force of the toner adhering to the peripheral surface of the photosensitive drum 30, the fiber tip is brought into contact with the peripheral surface of the photosensitive drum 30, and is rotated at a counter or at a peripheral speed different from that of the photosensitive drum 30. Also, the fur brush 14 2, zinc stearate is supplied from the zinc stearate housing portion 144. As a result, the photosensitive drum 3
With the rotation of 0, so that the zinc stearate is applied to the photosensitive drum 30 peripheral surface with the fur brush 14 2.

The cleaning blade 143 is made of a resin plate member whose tip is pressed against the peripheral surface of the photosensitive drum 30, and scrapes off the toner on the peripheral surface of the photosensitive drum 30 whose binding force is weakened by the fur brush 142. It is composed. The toner removed from the peripheral surface of the photoconductor drum 30 is collected in the casing 141 and collected in a collection tank (not shown).
Will be collected. [Control System] A control unit 201 is provided inside the copying machine 1 as shown in FIG. The control unit 201 uses the CP
It is composed of a microcomputer system including U, RAM, ROM and various drivers. Control unit 201
An operation panel 202 for issuing various operation instructions is connected to the. The operation panel 202 includes an input key section including a numeric keypad and other command keys, a liquid crystal display element, and an LED.
It also includes a display unit configured by, for example, a start key for instructing the start of the copying operation, and a switch for setting the special paper mode.

The control unit 201 further includes an image reading unit 2
03 is connected. The image reading unit 203 includes the above-described optical system 23 and the like, irradiates a document placed on the document table 15 with light, and reflects light reflected from the document on the color image pickup device 2.
It is read at 9 and converted into an image data signal. The control unit 201 also receives an image data signal output from the color image sensor 29 and performs image processing on the image data.
4 is connected. In the image processing unit 204, a two-dimensional color image is restored by the image data signal output from the color image pickup device 29, and this is further converted into cyan,
Decomposes into images of magenta, yellow, and black color components.

An exposure section 205 including a laser unit 40 is connected to the control section 201. In the exposure unit 205, laser light is emitted from the laser unit 40 based on the image information decomposed into each color component by the image processing unit 204, and an electrostatic latent image is formed on the peripheral surface of the photosensitive drum 30.
Further, the control unit 201 is connected to a photoconductor drum drive unit 206 for driving the photoconductor drum 30 to rotate. The photoconductor drum drive unit 206 rotationally drives the photoconductor drum 30 in synchronization with the laser light emitted from the exposure unit 205.

Further, the control section 201 includes a paper transport system 20.
7 is connected. The paper transport system 207 includes a paper feed transport system including a drive motor 42 for rotationally driving the transfer belt 46, a paper discharge transport path 99, a fixing device 100, and a discharge motor including drive motors such as a pair of paper discharge rollers 103. It is composed of the system. The paper carrying system 207 can be set to at least one of the normal carrying speed and the special paper carrying speed which is slower than the normal carrying speed, and performs speed control according to the set mode. Is possible.

The control unit 201 includes a primary transfer upper roller 47.
A primary transfer roller control unit 208 for moving the pressure roller between the pressure contact position and the separation position is connected. The primary transfer roller control unit 208 drives and controls the primary pressing cam drive motor 56 to bring the primary transfer upper roller 47 into pressure contact with and away from the photosensitive drum 30.
In normal operation, the primary transfer upper roller 47 moves the transfer belt 46 together with the primary transfer lower roller 48 to the photosensitive drum 30.
The primary transfer upper roller 47 is moved to the press contact position so as to be pressed against the peripheral surface, and in the special paper mode, the primary transfer upper roller 47 separates the transfer belt 46 from the peripheral surface of the photosensitive drum 30. The next transfer upper roller 47 is moved to the separated position.

The control unit 201 includes a secondary transfer lower roller 67.
Secondary transfer roller control unit 2 for moving the sheet between a predetermined position at the time of transfer and a separated position separated from the transfer belt 46.
09 is connected. This secondary transfer roller control unit 20
Reference numeral 9 indicates that the secondary transfer lower roller 67 is moved toward and away from the transfer belt 46 by driving and controlling a motor that drives the secondary pressing cam. Photoconductor drum 30
During the primary transfer of the toner image from the transfer belt 46 to the transfer belt 46, the secondary transfer lower roller 67 is separated from the transfer belt 46, and the secondary transfer of the toner image from the transfer belt 46 to the sheet is performed.
When performing the secondary transfer, the secondary transfer lower roller 67 is moved so that the gap between the peripheral surface of the secondary transfer lower roller 67 and the surface of the transfer belt 46 becomes a predetermined distance.

Further, a secondary transfer voltage controller 210 for controlling the voltage applied to the secondary transfer lower roller 67 is connected to the controller 201. Secondary transfer voltage controller 2
Reference numeral 10 denotes a transfer belt 46 for attracting toner from the back surface of the paper onto the paper and transferring the toner image to the front surface of the paper.
A voltage having a polarity opposite to that of the surface toner is applied to the secondary transfer lower roller 67. When the toner is negatively charged, the voltage applied to the secondary transfer lower roller is a DC bias voltage of about +1 kV to 2.5 kV. Immediately after the apparatus returns from the stopped state, there is a possibility that toner is attached to the secondary transfer lower roller 67, and the secondary transfer voltage controller 210 applies a predetermined voltage to the secondary transfer lower roller 67 for a certain period of time. Both applied 2
The transfer belt 46 and the secondary transfer roller 67 are rotationally driven at a position where the lower secondary transfer roller 67 is close to the transfer belt 46. At this time, the voltage applied to the secondary transfer lower roller 67 has the same polarity as that at the time of transfer and is a DC bias voltage of about +300 to 400V. However, when the cleaning blade 75 is not in contact with the secondary transfer lower roller 67, the voltage at this time is preferably reverse polarity.

Still another input / output unit is connected to the control unit 201. [General Operation] The operation of the copying machine 1 thus configured will be described with reference to the flowchart shown in FIG.

When the power of the copying machine 1 is turned on, various parameters and the entire apparatus are initialized in step S1 shown in FIG. During this initialization operation, a toner separation voltage is applied to the secondary transfer lower roller 67 to apply the transfer belt 46.
And the secondary transfer lower roller 67 is rotationally driven for a predetermined time,
The operation includes re-transferring the toner attached to the next transfer lower roller 67 to the transfer belt 46 and collecting the toner to the cleaning device 62 provided on the transfer belt 46. The toner peeling voltage applied to the secondary transfer lower roller 67 is a DC voltage of +300 to 400 V when the cleaning blade 75 is in contact with the peripheral surface of the secondary transfer lower roller 67. After this,
The photoconductor drum 30, the transfer belt 46, etc. are set to the initial positions.

In step S2, it is determined whether or not the special paper mode is set. Here, the operation panel 20
When the special paper mode is selected by the mode setting button No. 2, it is determined that the special paper mode has been set, and the process proceeds to step S3. In step S3, an image forming process in the special paper mode is executed. When it is determined in step S2 that the special paper mode is not set, the process proceeds to step S4. In step S4, the apparatus is set to the normal image forming mode. In step S5, it is determined whether or not there is an instruction to start image formation. When the start key provided on the operation panel 202 is operated, it is determined that an instruction to start image formation has been given,
Control goes to step S6.

In step S6, an image is formed on the sheet based on the normal image forming mode. Here, a document placed on the document table 15 is irradiated with light by the optical system 23, and the reflected light is converted into an image data signal by the color image pickup device 29. The image data signal is decomposed into an image of each color component by the image processing unit 204, and first, an electrostatic latent image based on the cyan color component is formed on the photoconductor drum 30. This electrostatic latent image is visualized by the developing device 33 containing cyan toner.

The primary transfer upper roller 47 is the photosensitive drum 3
It is located at a pressure contact position close to the 0 side, and the transfer belt 46 together with the primary transfer lower roller 48 is in pressure contact with the peripheral surface of the photosensitive drum 30. As a result, the toner image of cyan color toner formed on the photosensitive drum 30 is transferred onto the surface of the transfer belt 46 by the primary transfer upper roller 47 and the primary transfer lower roller 48.

When the toner image of cyan color toner is transferred to the transfer belt 46, an electrostatic latent image corresponding to magenta is formed on the photosensitive drum 30, and similarly, the toner of color toner is used by the developing device 34. The image is visualized. This toner image is similarly transferred onto the transfer belt 46. Thereafter, in the same manner, the toner images of the respective color components of yellow and black are transferred onto the transfer belt 46 in a laminated state. When transferring the toner image of each color component,
The images are synchronized so that the images are not displaced.
At the same time, the paper feed cassettes 18, 19, 20, 21,
The sheet is conveyed from one of the bypass trays 22 and is made to stand by the registration rollers 98 in the sheet feeding passage 97.

When the transfer of the color toner image onto the transfer belt 46 is completed, a sheet is supplied from the registration roller 98 between the secondary transfer upper roller 45 and the secondary transfer lower roller 67, and is stacked on the surface of the transfer belt 46. The color toner image formed in this state is transferred onto the sheet by the secondary transfer lower roller 67. After that, the paper on which the color toner image is transferred is conveyed to the fixing device 100 through the paper discharge conveyance path 99, and the color toner image transferred on the paper surface is heated and melted and fixed, and then discharged onto the paper discharge tray 104. To do. During this time, 1
The next transfer upper roller 47 is located at the pressure contact position,
The surface of the transfer belt 46 is pressed against the peripheral surface of the photosensitive drum 30 by a primary transfer upper roller 47 and a primary transfer lower roller 48. Further, the paper transport system 207 is set to a normal transport speed in synchronization with the photosensitive drum drive unit 206.

In step S7, it is determined whether or not a predetermined image forming operation is completed. Here, the operation panel 20
When the copying operation for the number of sheets instructed from 2 is completed, it is determined that the predetermined image forming operation is completed, and step S8 is performed.
Move to. In step S8, other processing is executed. [Special Paper Mode] In the special paper mode in step S3, the operation as shown in FIG. 10 is executed. Step S1
At 1, it is determined whether or not there is an instruction to start image formation. Here, the paper feed cassettes 18 and 1 of the paper feed unit 17 are previously set.
Special paper for image formation is set on any one of 9, 20, 21 and the bypass tray 22, and the operation panel 202 gives an instruction to start feeding the special paper. Special paper is thick paper or OHP
It is a sheet or surface-coated paper with a surface coating, and is usually set in the bypass tray 22 in many cases. In this case, the setting for feeding from the bypass tray 22 may be indicated from the operation panel 202. .
After that, when the start key provided on the operation panel 202 is operated, it is determined that there is an instruction to start image formation, and the process proceeds to step S12.

In step S12, a process of reading the original image placed on the original table 15 and transferring the color toner image onto the transfer belt 46 is executed. In this case, similarly to the case of forming an image on plain paper, the original placed on the original table 15 is irradiated with light by the optical system 23, and the reflected light is imaged by the color image pickup device 29. Convert to signal. The image data signal from the color image pickup device 29 is decomposed into an image of each color component by the image processing unit 204, and an electrostatic latent image is formed on the peripheral surface of the photosensitive drum 30 in the order of cyan, magenta, yellow, and black. The developing devices 33, 34, 35, and 36 visualize the images, and the images are sequentially transferred to the transfer belt 46. At the same time, the paper feed unit 1
The paper is taken out from a position designated in advance in 7 and conveyed to the transfer device 37 side, and is made to stand by by the registration roller 98.

At this time, the primary transfer upper roller 47 is located at a pressure contact position which is close to the photosensitive drum 30 side, and the paper transport system 207 operates normally in synchronization with the photosensitive drum driving section 206. Driving each part at speed. In step S13, it is determined whether or not the primary transfer operation is completed. Here, when the transfer of the cyan, magenta, yellow, and black toner images onto the transfer belt 46 is completed, it is determined that the primary transfer operation is completed, and the process proceeds to step S14.

In step S14, the primary transfer upper roller 4
7 is moved to the separated position to separate the surface of the transfer belt 46 from the peripheral surface of the photoconductor drum 30, and the paper transport speed of the paper transport system 207 is set to a special paper transport speed slower than the transport speed in the normal operation. To do. This special paper conveyance speed is set to such a speed that the color toner image transferred in a stacked state on the surface of material paper such as thick paper, OHP sheet, and surface coated paper is sufficiently melted and fixed in the fixing device 100.

In step S15, the registration roller 98
The sheet of paper that has been made to stand by is conveyed to the transfer device 37, and the secondary transfer operation for this paper is started. Here, the secondary transfer upper roller 45 is driven by the special paper transport speed, and the paper is transported by this special paper transport speed, and the color toner image formed on the transfer belt 46 is transferred onto the paper. . After that, the paper on which the color toner image is transferred is conveyed to the fixing device 100, the color toner on the paper surface is melted and fixed, and the paper discharge roller pair 1
The sheet is discharged to the sheet discharge tray 104 by 03.

In step S16, it is determined whether or not a predetermined image forming operation has been completed. Here, the operation panel 2
When the copying operation for the number of sheets instructed from 02 is completed,
When it is determined that the predetermined image forming operation is completed, the process returns to the main routine. In this case, when the image formation is performed on the material paper such as the thick paper, the OHP sheet, and the surface coated paper, when the transfer of the toner image to the transfer belt 46 is completed, the primary transfer upper roller 47 is formed. Is moved to a separating position to separate the surface of the transfer belt 46 from the peripheral surface of the photoconductor drum 30, and the sheet is conveyed at a special sheet conveying speed that is lower than the normal conveying speed of the sheet conveying system 207. Therefore, the color toner image transferred onto the sheet can be sufficiently fused and fixed, and the photosensitive drum 3
It is possible to prevent the peripheral surface of 0 from rubbing against the transfer belt 46 and being damaged. [Secondary Transfer Voltage Control] During the secondary transfer for transferring the toner image on the surface of the transfer belt 46 onto the sheet, the voltage applied to the secondary transfer lower roller 67 by the secondary transfer voltage controller 210 is the transfer belt. + 1kV of opposite polarity to the toner on 46
It is set to 2.5 kV.

At the time of initial setting immediately after the power is turned on, as described above, the toner separation voltage is applied to the secondary transfer lower roller 67 to transfer the transfer belt 46 and the secondary transfer lower roller 67.
Is rotationally driven for a certain period of time, the toner adhering to the secondary transfer lower roller 67 is retransferred to the transfer belt 46, and a roller initialization operation is performed to collect the toner on a cleaning device 62 provided on the transfer belt 46. In this case, the cleaning blade 75 is provided in pressure contact with the secondary transfer lower roller 67, and the toner separation voltage applied to the secondary transfer lower roller 67 by the secondary transfer voltage controller 210 is the toner on the surface of the transfer belt 46. And +300 to 400V, which is the opposite polarity.

When the paper jam or the device cover is opened, the device is stopped. The operation at this time is shown in a flowchart in FIG. In step S21, it is determined whether a paper jam has occurred. Here, it is provided at various places such as the vertical conveyance path 81 of the paper feed section 17, the bypass conveyance path 82, the paper feed conveyance path 97, the paper ejection conveyance path 99, and the path from the fixing device 100 to the paper ejection roller pair 103. It is determined based on the detection signal of the paper detection sensor whether the paper is normally conveyed. For example, if any of the paper detection sensors does not detect a paper even after a predetermined time,
When it is determined that a paper jam has occurred, the process proceeds to step S23.

In step S22, it is determined whether or not the device cover is open. For example, a sensor that turns off when the device cover is in the closed position at a predetermined position and turns on when the device cover is in the open state is provided, and the device cover opens based on the detection signal of this sensor. It is possible to determine whether or not there is. If the device cover is open, the process proceeds to step S23.

In step S23, the apparatus is stopped to prohibit the operation instruction input from the operation panel 202, and the location of the paper jam on the liquid crystal display of the operation panel 202 and the opened apparatus cover position. Is displayed in correspondence with the current situation. In step S24,
It is determined whether the return work is completed. For example, when a paper jam occurs, it is determined that the restoration work is completed when the paper is removed from the location where the jam occurs and the reset switch is operated. Further, when the device cover is opened and the sensor is turned off and the device cover is in the closed state, it is determined that the restoration work is completed. However, in order to remove the paper from the location where the paper jam occurred, it is necessary to open the device cover and perform the paper removal work.If the device is stopped due to the paper jam, the device cover is closed. Things are included in the return work. Therefore, here, the case where the apparatus cover is opened is, for example, a case where an operation inside the apparatus is performed due to toner replenishment or other maintenance, or when the apparatus cover is accidentally opened. In this step S24,
If it is determined that the return work is completed, the process proceeds to step S25.

In step S25, the same roller initialization work as immediately after the power is turned on is performed. Here, the secondary transfer lower roller 67 has a polarity of +30 opposite to that of the toner on the surface of the transfer belt 46.
By applying a toner peeling voltage of 0 to 400 V, the transfer belt 46 and the secondary transfer lower roller 67 are rotationally driven for a fixed time (here, 3 seconds). As a result, the toner attached to the secondary transfer lower roller 67 is retransferred to the transfer belt 46, and the cleaning device 6 provided on the transfer belt 46.
Collect to 2.

For example, when the transfer of the toner image onto the transfer belt 46 is completed and a paper jam occurs at the registration roller 98 when the secondary transfer is started, the paper is not conveyed to the transfer portion. Nevertheless, the voltage application to the secondary transfer lower roller 67 is started, and the toner on the transfer belt 46 is transferred to the secondary transfer lower roller 67. Since the distance between the registration roller 98 and the transfer portion (the position where the transfer belt 46 and the secondary transfer lower roller 67 are close to each other) is short, when the occurrence of a paper jam is detected, the voltage application to the secondary transfer lower roller 67 is already started. The toner is transferred to the secondary transfer lower roller 67. When the jammed paper is removed and the apparatus returns from the stopped state, the secondary transfer lower roller 67
If the toner adhered to is left as it is, the toner adheres to the back surface side of the paper at the time of the next image formation, and the paper is contaminated. Therefore, when the apparatus returns from the stopped state, a predetermined toner peeling voltage is applied to the secondary transfer lower roller 67 to retransfer to the transfer belt 46 side, and the cleaning apparatus 62 collects the toner.

Even when the apparatus is stopped except for the paper jam in the registration roller 98, there is a possibility that toner is attached to the secondary transfer lower roller 67, and when the apparatus returns from the stopped state. The secondary transfer lower roller 6 is always applied for a predetermined time by applying the toner peeling voltage as described above.
7 and the transfer belt 46 are rotationally driven.

The toner peeling voltage is the secondary transfer lower roller 67.
Of the cleaning blade 75 that is pressed against the surface of No. 1 differs from that of No. In the case of the above-described embodiment, since the cleaning blade 75 is pressed against the surface of the secondary transfer lower roller 67, it is preferable to apply a voltage having a polarity opposite to that of the toner on the surface of the transfer belt 46. Two
Toner is forcibly attached to the secondary transfer lower roller 67, and the voltage applied to the secondary transfer lower roller 67 is set to -200V, -150V.
V, -100V, -50V, 0V, + 50V, +100
Table 1 shows the cleaning performance when V and +200 V are set and the voltage application time is 3 seconds. From this, when the applied voltage is a negative voltage of the same polarity as the toner, the effect of peeling off the toner adhering to the secondary transfer lower roller 67 becomes poor, and when the applied voltage is a positive voltage of the opposite polarity to the toner, the secondary transfer It was found that the effect of removing the toner adhering to the roller 67 was good.

If there is no cleaning blade 75 that presses against the peripheral surface of the secondary transfer lower roller 67, it is preferable to apply a voltage having the same polarity as the toner. When the cleaning blade 75 is not provided, the toner is forcibly attached to the secondary transfer lower roller 67, and the voltage applied to the secondary transfer lower roller 67 is -500V, -400V, -300V, -20.
0V, -150V, -100V, -50V, 0V, +5
Set to 0V and + 100V, and set the voltage application time to 3
The cleaning performance in seconds is shown in Table 1. From this, when the cleaning blade 75 is not provided and the applied voltage is a negative voltage having the same polarity as the toner, the effect of separating the toner adhering to the secondary transfer lower roller 67 is good, and the applied voltage is a positive voltage having the opposite polarity to the toner. In the case of voltage,
It was found that the peeling effect of the toner adhering to the secondary transfer lower roller 67 deteriorates.

[0068]

[Table 1]

As described above, when the apparatus returns from the stopped state, the toner peeling voltage is applied to the secondary transfer lower roller 67 to retransfer the adhered toner to the secondary transfer lower roller 67 for cleaning. Therefore, it is possible to prevent the toner from adhering to the back surface of the paper and being contaminated. [Copy Control for Multiple Copies] When a copy process for multiple copies is selected by an instruction from the operation panel 202, the operation is performed based on the flowchart shown in FIG.

In step S31, the copy number n designated by the operation panel 202 is substituted into the variable k. In step S32, the optical system 2 is added to the original placed on the original table 15.
3 is used to irradiate light, the reflected light is converted into an image data signal by the color image pickup device 29, and the original image is read. In step S33, the color image sensor 2
The image data signal converted by the image processing unit 2
By 04, it is decomposed into images of each color component.

In step S34, it is determined whether or not the size of the original set on the original table 15 or the paper size designated by the operation panel 202 is A4 landscape or smaller.
The size of the paper to be copied exceeds A4 landscape, eg A3
If it is the size, the process proceeds to step S35. In step S35, a normal image forming operation is performed in which a toner image based on the original image is formed on the peripheral surface of the photoconductor drum 30, and the toner image is transferred onto the surface of the transfer belt 46 and further transferred onto a sheet. In this case, the toner image based on each color component of the original image is laminated on the surface of the transfer belt 46 with the leading edge positioned based on the detection signal detected by the photo interrupter 122 in the detection hole 120 of the transfer belt 46. . As described above, the widthwise end portion of the transfer belt 46 is provided with the six detection holes 120 at equal intervals in the rotation direction, and cyan toner from the photosensitive drum 30 is generated based on the first detection signal. The transfer of the image to the surface of the transfer belt 46 is started. After this, the photo interrupter 1
The counting of the detection signal output by 22 is started, and the transfer of the toner image by magenta is started based on the sixth detection signal. Similarly, the yellow and black toner images are transferred based on the sixth detection signal, and a full-color image in which the toner images of the respective color components are stacked is formed on the transfer belt 46. Further, the secondary transfer is started based on the predetermined number of detection signals. This ensures the positioning of the front end of the transferred toner image, and can start image formation based on the detection signal by the earliest one of the six detection holes 120 at the start of transfer. The waiting time at the start of image formation is reduced, and the processing time can be shortened.

When the copying operation for one sheet is completed, the value of the variable k is decremented and the above operation is repeated until the value of the variable k reaches 0. When it is determined in step S34 that the size of the paper to be copied is A4 landscape or smaller, the process proceeds to step S36. Step S3
At 6, it is determined whether the photo interrupter 122 has output a predetermined detection signal. Here, the process proceeds to step S37 based on the detection signal when the photo interrupter 122 first detects the detection hole 120.

In step S37, the transfer of the toner image by the color component of the first color of the first image onto the transfer belt 46 is started. Here, the color component of the first color is cyan. At this time, counting of the detection signal output from the photo interrupter 122 is started. In step S38, it is determined whether or not the detection signal of the photo interrupter 122 has reached a predetermined number. Here, when the count number of the detection signal of the photo interrupter 122 reaches "3", it is determined that the count has reached a predetermined number, and the process proceeds to step S39. At this time, the transfer belt 46 has made 1/2 rotation after the transfer of the toner image by the first color component of the first image is started, and the size of the paper to be copied is A4 landscape or smaller. The transfer operation of the toner image of the first image onto the transfer belt 46 is completed.

In step S39, transfer of the toner image by the color component of the first color of the second image onto the transfer belt 46 is started. At this time, the count of the detection signal output from the photo interrupter 122 is reset and a new count is started. In step S40, it is determined whether or not the detection signal of the photo interrupter 122 has reached a predetermined number. Here, when the count number of the detection signal of the photo interrupter 122 becomes “3”, it is determined that the count has reached the predetermined number, and the process proceeds to step S41. At this time, the transfer belt 46 has rotated once since the transfer of the toner image by the first color component of the first image was started. Therefore, the transfer of the toner image onto the transfer belt 46 by the second color component of the first image is started. Here, the color component of the second color is magenta. Further, the count number of the detection signal of the photo interrupter 122 is reset. In step S42, it is determined whether or not the detection signal of the photo interrupter 122 has reached a predetermined number. Similarly to the above, when the count number of the detection signal of the photo interrupter 122 becomes “3”, it is determined that the count has reached the predetermined number, and the process proceeds to step S43.

In step S43, the transfer of the toner image by the second color component of the second image onto the transfer belt 46 is started. At this time, the count of the detection signal output from the photo interrupter 122 is reset and a new count is started. In step S44, it is determined whether or not the detection signal count number of the photo interrupter 122 is "3". When the count number of the detection signal of the photo interrupter 122 becomes "3", the process proceeds to step S45.

In step S45, the transfer of the toner image by the third color component of the first image onto the transfer belt 46 is started. Here, the third color component is yellow. Further, the count number of the detection signal of the photo interrupter 122 is reset. In step S46, it is determined whether or not the count number of the detection signal of the photo interrupter 122 has reached "3". When the number of detection signals of the photo interrupter 122 reaches "3", the process proceeds to step S47.

In step S47, the transfer of the toner image by the color component of the third color of the second image onto the transfer belt 46 is started. At this time, the count of the detection signal output from the photo interrupter 122 is reset and a new count is started. In step S48, it is determined whether or not the detection signal count number of the photo interrupter 122 has become "3". When the count number of the detection signal of the photo interrupter 122 becomes "3", the process proceeds to step S49.

In step S49, transfer of the toner image by the color component of the fourth color of the first image onto the transfer belt 46 is started. Here, the fourth color component is black. Further, the count number of the detection signal of the photo interrupter 122 is reset. In step S50, it is determined whether or not the count number of the detection signal of the photo interrupter 122 has reached "3". When the count number of the detection signal of the photo interrupter 122 becomes “3”, the process proceeds to step S51.

In step S51, transfer of the toner image by the color component of the fourth color of the second image onto the transfer belt 46 is started. At this time, the count of the detection signal output from the photo interrupter 122 is reset and a new count is started. In step S52, it is determined whether or not the count number of the detection signal of the photo interrupter 122 has reached a predetermined number. Here, when the count number of the detection signal of the photo interrupter 122 reaches a predetermined number, the front end position of the first image is set to reach a predetermined position near the secondary transfer position, and the detection of the photo interrupter 122 is performed. When the signal count reaches the predetermined number, the count is reset to newly start the detection signal count, and the process proceeds to step S53.

In step S53, the sheet already waiting by the registration rollers 98 is conveyed to the transfer device 37 side, a predetermined voltage is applied to the secondary transfer lower roller 67, and the secondary transfer operation for the sheet is started. . At this time, at the same time, the next sheet is conveyed from the sheet feeding unit 17 and the registration roller 98
To wait. As a result, the first image formed on the transfer belt 46 is transferred to the paper. When the count number of the photo interrupter 122 reaches “3”, the secondary transfer operation of the first image has already been completed,
The leading end position of the second image has reached a predetermined position near the secondary transfer position. Therefore, the sheet of paper which is kept waiting by the registration roller 98 is conveyed to the transfer device 37 side, a predetermined voltage is applied to the secondary transfer lower roller 67, and the secondary transfer operation for the sheet is started. When the secondary transfer operation of the two images is completed, the process proceeds to step S54. Step S54
Then, "2" is subtracted from the variable k indicating the number of copies remaining. In step S55, the value of the variable k is compared with "1". When the value of the variable k is larger than “1”, the process proceeds to step S36 and the same image forming operation is repeated. If the value of the variable k is "1", step S3
Go to 5. This corresponds to the final copy when an odd number is selected as the number of copies, and in this case, only one image needs to be formed on the transfer belt 46, so that normal image formation in step S35 is performed. It suffices to perform processing. If the value of the variable k is smaller than 1, it is determined that all the instructed copy numbers have been processed, and the step S
Move to 56. In step S56, end processing is performed.

In the embodiment configured as described above, the detection hole 12 provided at the widthwise end edge of the transfer belt 46.
0 is provided at six positions at equal intervals in the rotation direction, and a transfer timing signal can be generated at the timing at which any of the detection holes 120 is detected by the photo interrupter 122, and the waiting time is shortened and the processing time is also reduced. It can be shortened. [Zinc stearate application control] Also, the operation panel 202
When a copy operation is instructed from, it is regarded as one operation even in the case of an instruction to copy a plurality of copies,
The instructed copy number is continuously processed, and zinc stearate is applied to the surface of the transfer belt 46 by the zinc stearate applying device 59 each time each operation is completed. Further, the number of times the toner image is transferred onto the surface of the transfer belt 46 is counted, and even when the number of times of transfer reaches a predetermined number, zinc stearate is transferred to the transfer belt 46.
It is configured to be applied to the surface. This will be described based on the flowchart shown in FIG.

In step S61, a copy operation instruction is accepted. For example, when a copy operation instruction is given from the operation panel 202, the number of copies, presence / absence of double-sided copy, whether a monocolor copy instruction or a full-color copy instruction is determined, and based on these instructions, an image of one operation is displayed. Set the forming operation. In step S62, step S6
Based on the image forming operation of one operation set in 2, the number of times l of performing the secondary transfer operation from the transfer belt 46 to the sheet is set. For example, when 10 copies are produced from one original, the number of times l of the secondary transfer operation is set to "10".

In step S63, a primary transfer operation of forming a toner image on the photosensitive drum 30 and transferring it to the transfer belt 46 and a secondary transfer operation of transferring the toner image from the transfer belt 46 onto the paper are performed. In step S64, "1" is subtracted from the variable l indicating the number of copies remaining in the operation, and zinc stearate is previously applied to the transfer belt 46, and then the toner image is transferred from the photosensitive drum 30 to the transfer belt 46. A predetermined number is added to the transfer number m indicating the total number of times. The predetermined number to be added to the transfer number m is, for example, "1" is added in the case of mono-color copying and "4" is added in the case of full-color copying. Further, in the case of double-sided copying, in order to increase the application frequency of zinc stearate, “2” may be added in the case of mono color and “8” may be added in the case of full color.

In step S65, it is determined whether or not the transfer number m exceeds a predetermined number M. The predetermined number M is the transfer number m
Is a threshold value that is set so that zinc stearate is applied to the transfer belt 46 when this number is reached,
For example, it is set to about 200 to 240. As a result, in the case of a mono-color only copying operation, it is 200 to 24
It is considered that this threshold value is reached when copying is performed on 00 sheets, and 50 is set when only full-color copying operation is performed.
It is considered that this threshold value has been reached when copying is performed for 60 sheets. In case of double-sided copying,
In the case of full-color copying, it is considered that this threshold value has been reached when the copying operation is performed on 25 to 30 sheets.

If it is determined in step S65 that the transfer count m has reached the threshold value M, the process proceeds to step S66. In step S66, the zinc stearate coating brush 60 is brought into contact with the transfer belt 46 to move the transfer belt 4
6 is rotationally driven to apply zinc stearate to the surface of the transfer belt 46. In step S 6 7, a developing device 36 for storing black toner is brought into contact with the peripheral surface of the photosensitive drum 30 and the developing roller and driven to execute the development aging.

When the transfer belt 46 is rotationally driven in step S66, the photosensitive drum 30 also rotates at the same time. At this time, zinc stearate is applied to the peripheral surface of the photosensitive drum 30 by the fur brush 142 of the cleaning device 38. However, when an electrostatic latent image is not formed on the peripheral surface of the photosensitive drum 30 and no developing device is driven, the photosensitive drum 30
The amount of zinc stearate applied to the peripheral surface is excessive. Therefore, the black developing device 36 is driven to bring the magnetic brush of toner formed on the developing roller into contact with the peripheral surface of the photosensitive drum 30, thereby removing the excess zinc stearate on the peripheral surface of the photosensitive drum 30. can do. In step S68, it is determined whether or not a predetermined time has elapsed.
Here, the predetermined time can be set to about 20 seconds.
When 20 seconds have elapsed in step S68, the application of zinc zinc stearate and the development aging are stopped, and the process proceeds to step S69. As a result, zinc stearate can be sufficiently applied to the surface of the transfer belt 46, and it is possible to prevent the formation of a hollow image in the formed image. In step S69, the variable m indicating the total number of transfers is reset, and the process proceeds to step S70.

In step S70, it is determined whether or not the remaining copy number l in the operation is larger than "0". When the number of remaining copies l is larger than "0", the process proceeds to step S63 and the next copy operation is executed. In step S70, the remaining copy number l is "0".
When it reaches, the process proceeds to step S71. In step S71, the zinc stearate coating brush 60 is brought into contact with the transfer belt 46 to rotationally drive the transfer belt 46, and zinc stearate is applied to the surface of the transfer belt 46. In this case, zinc stearate is applied during one rotation of the transfer belt 46 after the sheet has passed the secondary transfer position. For example, if it takes about 6 seconds for the transfer belt 46 to make one rotation, the zinc stearate coating brush 60 is brought into contact with the transfer brush 46 and the transfer belt 46 is rotated for about 6 seconds. it can. In this case, at the same time, the developing device 36 is connected to the photosensitive drum 30.
The developing roller may be driven by bringing it into contact with the peripheral surface of the developing roller to perform the developing aging.

In this way, on the transfer belt 46,
Since zinc stearate is applied for each operation, it is possible to prevent the toner image transferred onto the sheet from suffering a defect such as a hollow image. Immediately after the transfer of the toner image onto the paper is completed, the transfer belt 46 is moved to about 1
Since zinc stearate is applied by rotating, the processing time is short and the user does not have to wait.

Even when the number of copies in one operation is large, zinc stearate is applied to the surface of the transfer belt 46 when the number of times the toner image is transferred onto the transfer belt 46 reaches a predetermined value. Therefore, the transfer belt 4
6 Zinc stearate on the surface is not insufficient, and obstacles such as hollow holes can be prevented. When the zinc stearate is applied onto the transfer belt 46, the photosensitive drum 30 also rotates at the same time, so that the zinc stearate is applied to the peripheral surface of the photosensitive drum 30 by the fur brush 142. Since the developing device 36 is driven to perform development aging, excess zinc stearate on the peripheral surface of the photosensitive drum 30 is removed by the developing device 36. Therefore, the zinc stearate applied to the peripheral surface of the photoconductor drum 30 is kept in an appropriate amount. [Other Embodiments] (A) Reflecting members such as aluminum foils are provided at six end portions in the width direction of the transfer belt 46 at equal intervals in the rotation direction,
A light emitting portion such as an LED that irradiates the reflecting member with light and a light receiving portion such as a phototransistor that receives the light reflected from the reflecting member are arranged and used as a transfer timing signal based on the output signal of the phototransistor It is also possible. (B) Although the six detection holes 120 are provided in the above-described embodiment, the number is not limited to this, and four or six detection holes 120 are provided.
It is also possible to provide them in an even number of places. (C) In the above embodiment, the photo interrupter 122 is used.
The secondary transfer timing signal is generated based on the detection signal of the second transfer timing. However, the detection signal of the photo interrupter 122 and a timer may be used to generate the secondary transfer timing signal. It is also possible to additionally provide a photo interrupter for generating a secondary transfer timing signal. (D) An automatic document feeder (ADF) is provided and is of a size capable of forming two toner images on the transfer belt 46 when performing a copy operation based on a plurality of documents inserted in the ADF. When performing image formation on paper, 2
It can be configured such that one original image is read, two toner images are formed in parallel on the transfer belt 46, and this is continuously secondarily transferred to two sheets. In this case, similarly to the case of the above-described embodiment, the transfer timing signal is generated based on the detection signal of the photo interrupter 122, and the toner image based on the two originals is formed on the transfer belt 46. After the toner images based on the respective color components are formed in a laminated state, the secondary transfer is continuously performed on two sheets of paper. When the number of originals is an odd number, normal transfer processing is performed only on the final original.

With this configuration, the ADF
It is possible to perform the copying process using the high speed. (E) In the above-described embodiment, there is a difference in peripheral speed between the intermediate support surface and the edge support surface of each roller. On the other hand, the intermediate inner peripheral surface 112 of the transfer belt 46 and the meandering prevention ridge 1
The inner peripheral surface 114 of the edge of 13 moves at the same speed in the straight portion. Therefore, the intermediate inner peripheral surface 1 of the transfer belt 46
12 and the edge inner peripheral surface 114 of the meandering prevention protrusion 113 are in contact with the intermediate support surface and the edge support surface of the roller, slippage occurs, and wear of parts becomes a problem.

In order to solve such a problem, an embodiment in which each roller has a structure as shown in FIG. 13 is shown. Here again, the primary transfer upper roller 47 is shown as an example. The primary transfer upper roller 47 has an intermediate inner peripheral surface 112 of the transfer belt 46.
It has a roller body 131 for supporting the. The roller main body 131 has an almost same width as the intermediate inner peripheral surface 112 of the transfer belt 46, and an outer peripheral surface of the roller main body 131 constitutes an intermediate support surface 132 that abuts and supports the intermediate inner peripheral surface 112 of the transfer belt 46. ing.

Further, at both ends of the roller body 131, support rollers 133 rotatably supported by a rotation shaft (not shown) of the roller body 131 are provided. Supporting roller 133
Is larger than the diameter of the roller body 131 and is a protrusion 113 for preventing meandering.
The diameter is set to be smaller by the height of the transfer belt 46, and the outer peripheral surface of the transfer belt 46 has a width substantially the same as the width of the meandering-preventing ridge 113 of the transfer belt 46. An end support surface 134 that supports 114 is configured.
The support roller 133 is rotatably supported independently of the roller body 131.

As a result, the intermediate inner peripheral surface 112 of the transfer belt 46 comes into contact with the intermediate supporting surface 132 of the roller body 131, and the end inner peripheral surface 114 of the meandering-preventing rib 113 is supported by the end supporting surface of the supporting roller 133. The transfer belt 46 is supported on the outer peripheral surface of the primary transfer roller 47 by coming into contact with the roller 134. Primary transfer lower roller 48, cleaning roller 63, secondary transfer upper roller 45, tension roller 4
9. Each of the driving rollers 44 has a roller body and a supporting roller, like the primary transfer upper roller 47 described above. As a result, the transfer belt 46
Is abutted against the outer peripheral surfaces of the roller body and the support roller at the widthwise intermediate portion and the widthwise end edge portion, respectively, and is evenly supported, so that the outer peripheral surfaces are not uneven. Since the support roller 133 can be independently rotated regardless of the rotation of the roller body 131, there is no difference in peripheral speed even if the roller body 131 and the support roller 133 have different diameters. Therefore, slippage does not occur between the inner peripheral surface of the transfer belt 46 and each roller, and it is possible to prevent the life of each component from being shortened due to wear. (F) The cleaning device 62 may be provided with a fur brush having fibers planted on its peripheral surface, and zinc stearate may be applied to the surface of the transfer belt 46. In this case, the cleaning roller 6 of the cleaning device 62
When 5 comes into contact with the transfer belt 46, at the same time, this fur brush passes through the secondary transfer position of the transfer belt 46, and the portion where the transfer of the toner image to the paper is completed is cleaned by the cleaning roller 65. At the same time, the application of zinc stearate with a fur brush can be performed automatically.

[0094]

According to the present invention, since the lubricant applied to the peripheral surface of the image bearing member is removed by the lubricant removing means, the image is formed with good image quality without fog. It can be performed.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view of a copying machine adopting an embodiment of the present invention.

FIG. 2 is an enlarged view of a main part thereof.

FIG. 3 is a perspective view for explaining a main part.

FIG. 4 is a partial vertical sectional view thereof.

FIG. 5 is a perspective view showing a relationship between a transfer belt and rollers.

FIG. 6 is a vertical sectional view thereof.

FIG. 7 is a vertical cross-sectional view showing an edge portion of a transfer belt.

FIG. 8 is a control block diagram.

FIG. 9 is a control flowchart of one embodiment.

FIG. 10 is a control flowchart of one embodiment.

FIG. 11 is a control flowchart of one embodiment.

FIG. 12 is a control flowchart of one embodiment.

FIG. 13 is a control flowchart of one embodiment.

FIG. 14 is a vertical cross-sectional view showing the relationship between a transfer belt and rollers of another embodiment.

[Explanation of symbols]

1 Copier 10 body 15 Platen 16 Image forming section 17 Paper feeder 22 Bypass tray 23 Optical system 30 photoconductor drum 33 Developing device 34 Developing device 35 developing device 36 Developing device 37 Transfer device 39 Exposure equipment 43 Secondary transfer upper roller 46 transfer belt 47 Primary transfer upper roller 48 Primary transfer lower roller 59 Zinc stearate coating device 60 Zinc stearate coating brush 61 Zinc stearate storage 67 Secondary transfer lower roller 111 outer peripheral surface 112 Middle inner surface 113 Meandering prevention ridges 114 Inner peripheral surface 115 Intermediate support 116 Edge support part

Continuation of the front page (56) Reference JP-A-53-133439 (JP, A) JP-A-55-53384 (JP, A) JP-A-5-53485 (JP, A) JP-A-9-319274 (JP , A) JP-A-9-146433 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G03G 15/16-15/16 103 G03G 21/00 G03G 21/10-21 / 12 G03G 15/01-15/01 117 G03G 15/08-15/08 507

Claims (5)

(57) [Claims] 1. A photosensitive drum peripheral surface on which a latent electrostatic image is formed, and a plurality of developing devices for storing color toners based on color components forming a color image. Developing means for developing the electrostatic latent image of the toner image into a toner image, and the respective colors visualized on the peripheral surface of the photosensitive drum by being stretched between the driving roller and the driven roller and being rotationally driven together with the photosensitive drum. A transfer belt on which toner images formed by toner are transferred in a stacked state, a primary transfer unit that transfers the toner image from the peripheral surface of the photosensitive drum to the transfer belt, and when the photosensitive drum and the transfer belt are rotationally driven. A lubricant applying means for applying a lubricant to the peripheral surface of the photosensitive drum, and a lubricant for driving any one of the plurality of developing devices to remove the lubricant excessively applied to the peripheral surface of the photosensitive drum. Removal means and Toner from the transfer belt surface in the conveyed sheet surface
-Secondary transfer means for transferring an image, and toner peeling for promoting toner transfer during secondary transfer
Release agent applying means for applying an agent to the surface of the transfer belt, and transfer number counting means for counting the number of executions of the secondary transfer operation
If, and to comprise, count value by the transfer number counting means reaches a predetermined value
Remove the toner on the transfer belt by the release agent applying means.
After applying the release agent, the photoconductor drum is continued.
The extra lubricant applied to the peripheral surface is used as the lubricant removing means.
An image forming apparatus configured to be further removed . 2. The image forming apparatus according to claim 1 , wherein the lubricant is zinc stearate. Wherein said developing means, cyan, becomes magenta, yellow, four developing devices for black, also claim 1
Is an image forming apparatus according to 2. 4. The image forming apparatus according to claim 3 , wherein the lubricant removing means removes the lubricant excessively applied to the peripheral surface of the photosensitive drum by driving the black developing device. Wherein said toner release agent is zinc stearate, an image forming apparatus according to any one of claims 1 to 4.