JP2006235034A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a photosensitive drum and a static eliminating section having a light guide from interfering with each other during a mounting / demounting operation of the photosensitive cartridge, and to arrange the light guide close to and opposed to the photosensitive drum. It is an object of the present invention to provide an image forming apparatus capable of efficiently removing the residual potential on the surface of the photosensitive drum and forming a good image.
A static elimination unit 19 provided with a light guide is fixedly supported by a member that separates or abuts a transfer belt 53 on a photosensitive drum 21. As a result, as the transfer belt 53 is separated from the photosensitive drum 21 when the photosensitive cartridge is attached / detached, the static eliminating portion 19 having the light guide is separated from the photosensitive drum 21, so that the photosensitive drum 21 and the light guide are separated. Can be prevented from interfering with each other, and these can be arranged in close proximity to each other.
[Selection] Figure 5

Description

  The present invention relates to an image forming apparatus provided with a photosensitive cartridge that is detachable from a main body of the image forming apparatus.

  In image forming apparatuses such as printers, copiers, and facsimile machines, a charging unit, an image writing unit, and a developing unit are disposed around a latent image carrier such as a photoconductor. In addition, after the surface of the photosensitive member is uniformly charged by the charging unit, an electrostatic latent image is formed on the surface of the photosensitive member by the image writing unit, and the electrostatic latent image is developed in the developing unit to form an image. To do. However, as described in Patent Document 1, it has been conventionally known that image defects occur due to disturbance of the potential on the surface of the photoreceptor before charging. In order to solve this problem, a so-called neutralization unit that removes the residual potential on the surface of the photoreceptor has been proposed.

  Such a charge eliminating unit is configured to remove the residual potential by irradiating the surface of the photoreceptor with light. For example, as a conventionally known one, a plurality of LEDs (Light Emitting Diodes) arranged in the longitudinal direction of the photoconductor are arranged opposite to the photoconductor, and the residual potential on the surface of the photoconductor by the light from the LEDs. There is a way to get rid of. However, in order to irradiate uniform light on the surface of the photoconductor by a method of arranging a plurality of point light sources such as LEDs, it is necessary to arrange the LEDs somewhat densely facing the photoconductor. For this reason, the static elimination unit having such a configuration requires a large number of LEDs, and it is difficult to dispose the static elimination unit in the vicinity of the photosensitive member around which the charging unit, the developing unit, and the like are arranged.

  On the other hand, in order to improve the static elimination efficiency, it is necessary to irradiate the surface of the photosensitive member with as much light as possible from the static elimination portion. Therefore, it is desirable to dispose the charge eliminating portion near the photoconductor so that the light from the charge eliminating portion is not blocked by other members. Also, considering the miniaturization of the image forming apparatus, it is desirable to dispose the charge eliminating unit near the photoconductor. Therefore, it is desirable that the charge eliminating portion is small, but in order to meet such a demand, the light incident from the light emitting member for charge elimination is provided facing the photosensitive member in the longitudinal direction. Patent Document 1 or 2 proposes a static elimination section provided with a light guide that leads to the above. In this way, the static elimination section provided with the light guide guides the light from the static elimination light emitting member to the surface of the photosensitive member, so that it is not necessary to arrange a large number of light sources facing the photosensitive member and can be miniaturized.

JP-A No. 13-142365 (paragraph numbers [0008] [0009] [0015] [0018]) JP-A-14-278395 (paragraph numbers [0013] to [0018])

  However, even when the static eliminator provided with the light guide described above is used as the static eliminator, there are the following problems in disposing the static eliminator near the photoconductor. That is, in recent years, in an electrophotographic image forming apparatus, in order to facilitate maintenance, a photosensitive member, a developing unit that acts on the photosensitive member, a cleaning unit, and the like are integrated as a photosensitive cartridge, and the image forming apparatus main body is integrated. On the other hand, there is one that adopts a detachable method. When such a photoreceptor cartridge reaches a predetermined limit, it is removed from the image forming apparatus main body and discarded, or replaced with a new photoreceptor and reused. In the apparatus employing the photoreceptor cartridge system as described above, the following problems may occur when the charge eliminating portion is arranged near the photoreceptor. That is, when the photoconductor cartridge is attached or detached, the static eliminator and the photoconductor may interfere with each other and damage the photoconductor or the static eliminator.

  The present invention has been made in view of the above problems, and by preventing interference between the photoreceptor and the charge removal portion when the photoreceptor cartridge is attached or detached, the charge removal portion can be disposed near the photoreceptor, and is small in size. An object of the present invention is to provide an image forming apparatus capable of efficiently removing the residual potential on the surface of the photoreceptor and forming a good image.

  According to the present invention, a plurality of image forming stations for forming toner images of different colors on the surface of the respective photoreceptors are arranged side by side in the moving direction of the transfer belt, and formed on the surfaces of the plurality of photoreceptors. An image forming apparatus that forms a color image by superimposing and transferring a toner image on a surface of a transfer belt, and in order to achieve the above-described object, each of a plurality of image forming stations holds a photosensitive member included therein. The photosensitive member cartridge that is detachable from the apparatus main body, a light-emitting member for discharging light that emits light, and a surface facing the photosensitive member in a state in which the photosensitive cartridge is mounted on the apparatus main body. Each of the plurality of image forming stations, including a light guide that irradiates the surface of the photoconductor with the light emitted from the light emitting member through the facing surface. A plurality of primary transfer rollers arranged to face each other, a support member that rotatably supports the plurality of primary transfer rollers and supports a plurality of light guides, and moves the support member to move the plurality of primary transfer rollers. A roller separating / contacting means for separating or abutting the primary transfer roller with an image forming station facing each other with a transfer belt interposed therebetween, and for separating or bringing a plurality of light guides away from or in close proximity to each facing photoconductor; The apparatus further comprises belt separating means for separating the transfer belt from the plurality of image forming stations in conjunction with the separating operation of the plurality of primary transfer rollers by the separating and contacting means.

  In the image forming apparatus configured as described above, all the primary transfer rollers are separated from the opposed image forming stations by moving the support members that pivotally support all the primary transfer rollers by the roller separating and contacting means. (Roller separation operation) Further, the belt separating means separates the transfer belt from all the image forming stations in conjunction with the separating operation of these primary transfer rollers. Further, when the roller separation operation is executed by the roller separation contact means, all the light guides are separated from the opposing photoreceptors in accordance with the roller separation operation. Therefore, when the roller separation operation is executed prior to the attachment or detachment of the photosensitive cartridge, the transfer belt is separated from all the image forming stations, and all the light guides are separated from the opposing photosensitive members. . Therefore, the opposing surface of the light guide that irradiates light to the surface of the photoconductor can be disposed close to the photoconductor without considering the mutual interference between the light guide and the photoconductor when the photoconductor cartridge is attached or detached. Thus, it is possible to efficiently remove the residual potential on the surface of the photoreceptor and form a good image. In addition, the image forming apparatus main body can be reduced in size. Further, in the image forming apparatus according to the present invention, the light guide is fixedly supported by the support member that pivotally supports the primary transfer roller, thereby realizing separation of the light guide from the photosensitive member accompanying the roller separation operation. . Therefore, it is not necessary to separately provide a member for supporting the light guide and a means for separating the light guide from the photosensitive member, and the apparatus configuration can be simplified.

  In addition, a plurality of image forming stations that form toner images of different colors on the surface of the respective photoreceptors are arranged side by side in the moving direction of the transfer belt, and the toner images formed on the surfaces of the plurality of photoreceptors are arranged. Only the toner image formed on the surface of the photoreceptor of the specific image forming station among the multiple image forming stations is transferred to the transfer belt. In the image forming apparatus that selectively executes the monochromatic mode for forming a monochromatic image, each of the plurality of image forming stations holds the photosensitive member of each of the image forming stations. A photosensitive cartridge that is detachable from the main body, a light-emitting light emitting member that emits light, and the photosensitive cartridge are mounted on the apparatus main body. A neutralization unit comprising a light guide that has a facing surface facing the surface of the photosensitive member in a state where the photosensitive member surface is irradiated and irradiates the surface of the photosensitive member with light emitted from the light-emitting member for neutralization through the facing surface; A single-color primary transfer roller arranged opposite to the specific image forming station and a plurality of image forming stations arranged in one-to-one correspondence with each of all the image forming stations excluding the specific image forming station. A primary transfer roller for color, a primary transfer roller for monochrome, and a single color support member for fixing and supporting a light guide of a specific image forming station, and a plurality of primary transfer rollers for color The plurality of image forming stations except for the specific image forming station out of the plurality of image forming stations are rotatably supported. The color support member for fixing and supporting the color guide and the single color support member are moved so that the single color primary transfer roller is separated from or in contact with the specific image forming station with the transfer belt interposed therebetween, and the single color support member is fixed. The single-color roller separating / contacting means for moving the supporting light guide away from or in proximity to the opposing photoreceptor, and the color support member are moved so that all of the plurality of primary transfer rollers for color face each other. A color roller separating / contacting means for separating or abutting a plurality of light guides fixedly supported by the color support member from a photoconductor facing each other with a transfer belt sandwiched between the station and a single color The transfer belt is moved to the specific image forming station in conjunction with the separation operation of the primary transfer roller for single color by the roller separation contact means. The transfer belt is separated from all image forming stations except for the specific image forming station among the plurality of image forming stations in conjunction with the separating operation of the plurality of color primary transfer rollers by the color roller separating and contacting means. You may comprise so that the belt separation means to separate may further be provided.

  In the image forming apparatus configured as described above, the single color primary transfer roller facing the specific image forming station is separated from the specific image forming station by moving the single color supporting member by the single color roller separating and contacting means. (Single color roller separation operation). Further, by moving the color support member by the color roller separating and contacting means, all of the color primary transfer rollers facing each of all the image forming stations except for the specific image forming station among the plurality of image forming stations can be obtained. Are separated from the image forming stations facing each other (color roller separation operation). In addition, the belt separating means separates the transfer belt from the specific image forming station in conjunction with the single color roller separating operation, and the specific image forming station among the plurality of image forming stations in conjunction with the color roller separating operation. The transfer belt is separated from all the image forming stations except for. Further, when the single color roller separation operation is performed, the light guide fixedly supported by the single color support member is separated from the opposing photosensitive member, and when the color roller separation operation is performed, the color guide A plurality of light guides fixedly supported by the support member are configured to be separated from the opposing photoconductors. Therefore, when the single color roller separation operation and the color roller separation operation are performed simultaneously or sequentially prior to the mounting and removal of the photosensitive cartridge, the transfer belt is separated from all the image forming stations, and all the light guides are Each is separated from the opposing photoconductor. Therefore, the opposing surface of the light guide that irradiates light to the surface of the photoconductor can be disposed close to the photoconductor without considering the mutual interference between the light guide and the photoconductor when the photoconductor cartridge is attached or detached. Thus, it is possible to efficiently remove the residual potential on the surface of the photoreceptor and form a good image. In addition, the image forming apparatus main body can be reduced in size. In the image forming apparatus according to the present invention, the light guide included in the specific image forming station is fixedly supported by the single color supporting member that pivotally supports the single color primary transfer roller, and the plurality of color primary transfer rollers are pivotally supported. The plurality of light guides possessed by all the image forming stations except for the specific image forming station among the plurality of image forming stations are fixedly supported by the color support member, thereby causing the single color roller separating operation and the color roller separating operation. The light guide is separated from the photoreceptor. Therefore, it is not necessary to separately provide a member for supporting the light guide and a means for separating the light guide from the photosensitive member, and the apparatus configuration can be simplified.

  If necessary, after the color mode is performed, the single color primary transfer roller is separated from the specific image forming station by the single color roller separation and contact means, and the plurality of primary colors are separated by the color roller separation and contact means. Each of the transfer rollers may be separated from the opposing image forming station.

  As described above, when the single color roller separation operation and the color roller separation operation are executed, the transfer belt is separated from all the image forming stations by the belt separation means. Therefore, in the image forming apparatus configured as described above, the transfer belt is in contact with all the image forming stations during the execution of the color mode. By simultaneously or sequentially executing the roller separation operation for color and the roller separation operation for color, the transfer belt is separated from all the image forming stations. Further, when the single color roller separation operation and the color roller separation operation are executed as described above, all the light guides are separated from the opposing photoreceptors. Therefore, the opposing surface of the light guide that irradiates light on the surface of the photoconductor can be disposed close to the photoconductor without considering the mutual interference between the light guide and the photoconductor when the photoconductor cartridge is attached or detached. Thus, it is possible to efficiently remove the residual potential on the surface of the photoreceptor and form a good image. In addition, the image forming apparatus main body can be reduced in size.

  Further, at the time of executing the single color mode, the color primary transfer rollers may be separated from the image forming stations facing each other by the color separation contact means. In such an image forming apparatus, the single-color primary transfer roller may be separated from the specific image forming station by the single-color roller separating / contacting unit as necessary after execution of the single-color mode.

  In the image forming apparatus configured as described above, when the single color mode is executed, the color roller separating / contacting unit executes the color roller separating operation, and the belt separating unit interlocks with the color roller separating operation. Thus, the transfer belt is separated from all the image forming stations except the specific image forming station. Therefore, when the single color roller separation operation is performed after the single color mode is executed, the transfer belt is separated from the specific image forming station by the belt separation unit in conjunction with the single color roller separation operation. Thus, the transfer belt is separated. Furthermore, as described above, when the single color roller separation operation and the color roller separation operation are executed, all the light guides are separated from the opposing photoreceptors. Therefore, when the photosensitive cartridge is attached or detached after the monochrome mode is executed, the transfer belt is separated from all the image forming stations only by executing the monochrome roller separation operation by the monochrome roller separation contact means. The light guides are separated from the opposing photoconductors. Therefore, the opposing surface of the light guide that irradiates light on the surface of the photoconductor can be disposed close to the photoconductor without considering the mutual interference between the light guide and the photoconductor when the photoconductor cartridge is attached or detached. Thus, it is possible to efficiently remove the residual potential on the surface of the photoreceptor and form a good image. In addition, the image forming apparatus main body can be reduced in size.

  Further, it is also possible to further comprise a light emitting member separating means for separating the light-emitting light-emitting member from the photosensitive member as the light guide is separated from the photosensitive member in each of the plurality of image forming stations. In the image forming apparatus configured as described above, the light-emitting member for discharging is separated from the photosensitive member by the light-emitting member separating unit in accordance with the separation operation of the light guide from the photosensitive member when the photosensitive member cartridge is attached or detached. Accordingly, when disposing the charge eliminating unit close to the photosensitive member, the charge eliminating unit is disposed close to the photosensitive member without considering the mutual interference between the light emitting member for discharging and the photosensitive member when the photosensitive member cartridge is attached or detached. be able to. Therefore, it is possible to efficiently remove the residual potential on the surface of the photoreceptor and form a good image. In addition, the image forming apparatus main body can be reduced in size.

  In the above invention, the light emitting member is separated from the photosensitive member by using the light emitting member separating means, but the discharging light emitting member is integrally attached to the light guide at each image forming station. May be. By adopting such a configuration, the light emitting member is separated from the photosensitive member together with the light guide as the light guide is separated from the photosensitive member. Therefore, the light emitting member separating means can be omitted, and the apparatus configuration can be simplified.

(First embodiment)
FIG. 1 is a diagram showing a first embodiment of an image forming apparatus according to the present invention. FIG. 2 is a diagram showing an electrical configuration of the image forming apparatus of FIG. This device includes a color printing process for forming a full color image by superposing four color toners (developers) of black (K), cyan (C), magenta (M), and yellow (Y), and black (K). This is an image forming apparatus that selectively executes a monochromatic printing process for forming a monochrome image using only the toner. In this image forming apparatus, when an image forming command (printing command) is given to the main controller 510 from an external device such as a host computer, the engine controller 520 controls each part of the engine unit EG in accordance with the command from the main controller 510. Then, a predetermined image forming operation is executed, and an image corresponding to the image forming command is formed on a sheet (recording material) S such as copy paper, transfer paper, paper, and an OHP transparent sheet.

  In the housing main body 3 included in the image forming apparatus of the present embodiment, an electrical component box 5 containing a power circuit board, a main controller 510 and an engine controller 520 is provided. An image forming unit 7, a transfer belt unit 9, and a paper feed unit 11 are also disposed in the housing body 3. In FIG. 1, a secondary transfer unit 12, a fixing unit 13, and a sheet conveying mechanism 15 are disposed on the right side in the housing body 3. The paper feeding unit 11 is configured to be detachable from the apparatus main body 1. The paper feeding unit 11 and the transfer belt unit 9 can be removed and repaired or exchanged.

  The image forming unit 7 includes image forming stations Y (for yellow), M (for magenta), C (for cyan), and K (for black) for forming a plurality of different color images. In the present embodiment, the image forming station K corresponds to the “specific image forming station” in the present invention. Each of the image forming stations Y, M, C, and K is provided with a photosensitive drum 21 on which the respective color toner images are formed. Each photosensitive drum 21 is connected to a dedicated drive motor and is driven to rotate at a predetermined speed in the direction of arrow D21 in the figure. A charging unit 23, an image writing unit 29, a developing unit 25, a charge eliminating unit 19, and a photoconductor cleaner 27 are disposed around the photoconductive drum 21 along the rotation direction. These functional units perform a charging operation, a latent image forming operation, a toner developing operation, and a charge eliminating operation. In FIG. 1, the image forming stations of the image forming unit 7 have the same configuration, and therefore, for convenience of illustration, only some image forming stations are denoted by reference numerals, and the other image forming stations are omitted. .

  The charging unit 23 includes a charging roller whose surface is made of elastic rubber. The charging roller is configured to rotate in contact with the surface of the photosensitive drum 21 at the charging position, and at a peripheral speed in the driven direction with respect to the photosensitive drum 21 as the photosensitive drum 21 rotates. Followed rotation. The charging roller is connected to a charging bias generator (not shown). The charging roller is supplied with the charging bias from the charging bias generator and is charged at the charging position where the charging unit 23 and the photosensitive drum 21 come into contact with each other. The surface of 21 is charged.

  The image writing unit 29 is an array writing in which elements such as a liquid crystal shutter including a light emitting diode and a backlight are arranged in a line in the axial direction of the photosensitive drum 21 (direction perpendicular to the paper surface of FIG. 1). The head is used and is spaced from the photosensitive drum 21. The array-like writing head has a shorter optical path length and is more compact than the laser scanning optical system. Therefore, it can be disposed close to the photosensitive drum 21 and has the advantage that the entire apparatus can be reduced in size.

  In this embodiment, the photosensitive drums 21, 17 M, 17 C, and 17 K of the photosensitive drums 21, the charging unit 23, the developing unit 25, and the photosensitive unit cleaner 27 of the image forming stations Y, M, C, and K (see FIG. It is unitized as 2). Each of the photoconductor cartridges 17Y, 17M, 17C, and 17K is provided with nonvolatile memories 910, 920, 930, and 940 for storing information related to the photoconductor cartridge. The transmission / reception units 530Y, 530M, 530C, and 530K provided on the respective photosensitive cartridges and the transmission / reception units 5220Y, 5220M, 5220C, and 5220K provided on the main body side are arranged close to each other, and the CPU 5210 of the engine controller 520 Wireless communication is performed with the memories 910, 920, 930, and 940. In this way, information on each photoconductor cartridge is transmitted to the CPU 5210, and information in each memory 910, 920, 930, 940 is updated and stored.

  Next, details of the developing unit 25 will be described on behalf of the image forming station K. The developing unit 25 includes a toner storage container 31 for storing toner, two toner agitation supply members 33 and 35 disposed in the toner storage container 31, and a partition member 37 disposed in proximity to the toner agitation supply member 35. And a toner supply roller 39 disposed above the partition member 37, a developing roller 41 that contacts the toner supply roller 39 and the photosensitive drum 21 and rotates in a direction indicated by an arrow at a predetermined peripheral speed. It is comprised from the control blade 43 contact | abutted.

  In each developing unit 25, the toner stirred and carried by the toner stirring supply member 35 is supplied to the toner supply roller 39 along the upper surface of the partition member 37. Further, the toner thus supplied is supplied to the surface of the developing roller 41 via the toner supply roller 39. The toner supplied to the developing roller 41 is regulated to a predetermined layer thickness by the regulating blade 43 and is conveyed to the photosensitive drum 21. The charged toner is developed at a developing position where the developing roller 41 and the photosensitive drum 21 come into contact with each other by a developing bias applied to the developing roller 41 from a developing bias generator (not shown) electrically connected to the developing roller 41. Is moved from the developing roller 41 to the photosensitive drum 21, and the electrostatic latent image formed by the image writing unit 29 becomes obvious.

  The toner image that has been made visible at the developing position in this way is conveyed in the rotational direction D21 of the photosensitive drum 21, and then the primary transfer position TR1 where the transfer belt 53, which will be described later, and each photosensitive drum 21 come into contact with each other. 1 is primarily transferred to the transfer belt 53.

  The neutralization unit 19 exposes the surface of the photosensitive drum 21 after the toner image is primarily transferred to the transfer belt 53 to remove residual potential on the surface of the photosensitive drum. It is disposed downstream of the transfer position TR1 so as to face the surface of the photosensitive drum 21.

  FIG. 3A is a diagram showing the configuration of the charge removal unit 19 as viewed from the direction perpendicular to the arrow D19 in the figure, which is substantially parallel to the straight line connecting the primary transfer positions TR1 in each image forming station. It is. FIG. 3B is a perspective view thereof. In the present embodiment, the static elimination unit 19 includes two static elimination light emitting members 191 a and 191 b and a light guide 193, and has an integrated structure in which the light emission members 191 a and 191 b are respectively attached to both ends of the light guide 193. is doing. Further, the structure is symmetric with respect to a symmetry axis 19X indicated by a broken line in FIG.

  The light guide 193 is formed in a thin plate shape so that it can be disposed close to and opposed to the photosensitive drum 21. The light guide 193 has two light incident surfaces 194a and 194b on which light from the light-emitting members 191a and 191b for neutralization are incident at both ends in the major axis direction (left and right direction in FIG. 5A). Two light reflecting surfaces 195a and 195b that reflect the incident light, and a light irradiation surface 196 that irradiates the surface of the photosensitive drum with light reflected by the light reflecting surfaces 195a and 195b facing the photosensitive drum 21, respectively. Is provided. Further, the light reflecting surfaces 195a and 195b extend in the major axis direction of the light guide 193 so as to approach the light irradiation surface 196 from the both ends of the light guide 193 toward the inside of the light guide 193, and at the symmetry axis 19X. It is configured to be connected to each other.

  The neutralizing light-emitting members 191a and 191b are respectively disposed at both ends in the long axis direction of the light guide 193, and are opposed to the light incident surfaces 194a and 194b provided at both ends in the long axis direction of the light guide 193, respectively. LEDs 192a and 192b that are arranged to radiate light toward the inside of the light guide 193 are included therein.

  FIG. 3C is an enlarged view of the light reflecting surfaces 195a and 195b. As described above, the surface of each light reflecting surface is configured to have a number of step shapes as it proceeds from each end of the light guide 193 to the inside of the light guide 193 in the long axis direction of the light guide 193. The reason for configuring the surfaces of the light reflecting surfaces 195a and 195b in this way is as follows. In general, light emitted from a light source attenuates as the distance from the light source increases. Therefore, when the light reflectance of the surfaces of the light reflecting surfaces 195a and 195b is made uniform, the light reflecting surfaces 195a and 195b are reflected as the distance from the LEDs 192a and 192b, which are light sources that enter the light, increases. Light is reduced and unevenness occurs in the light irradiated from the light irradiation surface 196. Therefore, the above-described step shape is provided on the surfaces of the light reflecting surfaces 195a and 195b, and the light reflecting surfaces 195a and 195a and 195a and 195b have a higher reflectance as the distance from the LEDs 192a and 192b, which are light sources that respectively enter light, increases. A surface of 195b was constructed. With this configuration, uniform light is irradiated from the light irradiation surface 196, and the residual potential on the surface of the photosensitive drum 21 can be removed satisfactorily.

  As described above, the static elimination unit 19 in the present embodiment reflects the light incident from the static elimination light emitting members 191a and 191b toward the light irradiation surface 196 facing the surface of the photosensitive drum 21 by the light reflection surfaces 195a and 195b. Thus, the light guide 193 configured to irradiate the surface of the photosensitive drum 21 with uniform light and remove the residual potential on the surface is employed. The light guide 193 configured as described above can be reduced in size as compared with a structure in which a large number of LEDs are arranged facing the photosensitive drum 21, and the light guide 193 is disposed so as to be opposed to the photosensitive drum 21. be able to.

  Further, in this embodiment, a photoconductor cleaner 27 is provided in contact with the surface of the photoconductor drum 21 on the downstream side of the static eliminating unit 19 in the rotation direction D21 of the photoconductor drum 21. The photoconductor cleaner 27 abuts on the surface of the photoconductor drum to remove the toner remaining on the surface of the photoconductor drum 21 after the primary transfer.

  The transfer belt unit 9 includes a driving roller 49 disposed below the housing body 3, a driven roller 51 disposed obliquely above the driving roller 49, and stretched around these rollers in the direction of an arrow D53 shown in the drawing. A transfer belt 53 that is circulated and a tension roller 55 that is biased in a direction in which the transfer belt 53 is stretched are provided. Further, the transfer belt unit 9 is disposed on the inner side of the transfer belt 53 so as to face the respective photosensitive drums 21 included in the image forming stations Y, M, C, and K when the photosensitive cartridge is mounted. 57Y, 57M, 57C, 57K. These primary transfer rollers are electrically connected to a primary transfer bias generator 5250, respectively. The primary transfer rollers are brought into contact with the photosensitive drums 21 facing each other with the transfer belt 53 interposed therebetween, and the primary transfer bias is applied from the primary transfer bias generator 5250 at an appropriate timing. Thus, the toner image formed on the surface of each photoconductive drum 21 can be transferred onto the transfer belt 53 at the primary transfer position TR1 where the photoconductive drum and the transfer belt 53 come into contact with each other.

  The drive roller 49 circulates and drives the transfer belt 53 in the direction of the arrow D53 in the figure, and also serves as a backup roller for the secondary transfer roller 75. A rubber layer having a thickness of about 3 mm and a volume resistivity of 1000 kΩ · cm or less is formed on the peripheral surface of the drive roller 49. Secondary transfer is omitted by grounding through a metal shaft. A conductive path of the secondary transfer bias supplied from the bias generation unit via the secondary transfer roller 19 is used. Thus, by providing the driving roller 49 with a rubber layer having high friction and shock absorption, the sheet S enters the contact portion (secondary transfer position TR2) between the driving roller 49 and the secondary transfer roller 75. At that time, it is difficult for the impact to be transmitted to the transfer belt 53, and deterioration of image quality can be prevented.

  The primary transfer rollers 57Y, 57M, and 57C (corresponding to the “primary transfer roller for color” in the present invention) are rotatable about the color rotation shaft 59 in the direction of arrow D59 in the drawing and in this direction. Is rotatably supported by a color roller support frame 61 (corresponding to a “color support member” in the present invention) that is urged by. In addition, the color roller support frame 61 fixedly supports a plurality of charge removal units 19 included in each of the image forming stations Y, M, and C. Further, the color roller support frame 61 performs primary transfer when the arc surface of the color frame cam 65 fixed to the cam rotation shaft 63 rotated by the actuator 67 is brought into contact with the color roller support frame 61. The rollers 57Y, 57M, and 57C are in contact with the photosensitive drums 21 of the image forming stations Y, M, and C with the transfer belt 53 interposed therebetween, and a plurality of static elimination units 19 that are fixedly supported by the color roller support frame 61. The respective light irradiation surfaces 196 are configured so as to be close to the respective photosensitive drums 21 included in the respective image forming stations Y, M, and C. When the arc surface of the color frame cam 65 is removed from the color roller support frame 61, the primary transfer rollers 57Y, 57M, and 57C face the urging direction D59 of the color roller support frame 61, respectively. The plurality of static eliminating portions 19 fixedly supported by the color roller support frame 61 are also separated from the opposite photosensitive drums 21 (for color). Guide separation operation). Thus, in the present embodiment, the actuator 67, the cam rotation shaft 63, and the color frame cam 65 function as the “color roller separating and contacting means” in the present invention. The actuator 67 is electrically connected to an actuator control unit 5270 (FIG. 2), and is configured such that the rotation angle of the actuator 67 is adjusted by a signal from the actuator control unit 5270 corresponding to a command from the CPU 5210. ing.

  A primary transfer roller 57K (corresponding to a “monochromatic primary transfer roller” in the present invention) is rotatable about a monochrome rotation shaft 69 in the direction of an arrow D69 and is urged in that direction. It is rotatably supported by a monochrome roller support frame 71 (corresponding to the “monochromatic support member” in the present invention). Further, the monochrome roller support frame 71 fixedly supports the static eliminating unit 19 included in the image forming station K. The monochrome roller support frame 71 is primary when the arc surface of the monochrome frame cam 73 fixed to the cam rotation shaft 63 rotated by the actuator 67 is brought into contact with the monochrome roller support frame 71. The transfer roller 57K is in contact with the photosensitive drum 21 of the image forming station K with the transfer belt 53 interposed therebetween, and the light irradiation surface 196 of the static eliminating portion 19 fixedly supported by the monochrome roller support frame 71 is an image forming station. It is configured so as to be close to the photosensitive drum 21 of K. When the arc surface of the monochrome frame cam 73 is removed from the monochrome roller support frame 71, the primary transfer roller 57K is opposed to the photosensitive drum in the biasing direction D69 of the monochrome roller support frame 71. At the same time, the neutralization unit 19 fixedly supported by the monochrome roller support frame 71 is also separated from the photosensitive drum 21 facing it (single color guide separation operation). Thus, in the present embodiment, the actuator 67, the cam rotation shaft 63, and the monochrome frame cam 73 function as the “monochromatic roller separating and contacting means” in the present invention.

  Further, in the present embodiment, the arc surface of the color frame cam 65 overlaps the arc surface of the monochrome frame cam 73 and is shorter than the arc surface of the monochrome frame cam 73. Therefore, by adjusting the rotation angle of the actuator 67 by the actuator control unit 5270, the primary transfer rollers 57Y, 57M, and 57C are kept in contact with the photosensitive drum 21 of the image forming station K. Can be separated or brought into contact with the photosensitive drum 21 facing each other. Further, when the color roller separation operation is executed, the tension roller 55 moves in the direction in which the transfer belt 53 is stretched in conjunction with the separation operation, so that the transfer belt 53 is tensioned. 53 is also separated from the photosensitive drum 21 included in each of the image forming stations Y, M, and C (color belt separating operation). Accordingly, by appropriately adjusting the rotation angle of the actuator, color printing processing (FIG. 1) performed by bringing the transfer belt 53 into contact with all the photosensitive drums 21 of the image forming stations Y, M, C, and K; The single-color printing process (FIG. 4) performed by bringing the transfer belt 53 into contact with only the photosensitive drum 21 of the image forming station K and separating from the photosensitive drum 21 of the image forming stations Y, M, and C is selectively performed. Can be executed. In addition, since the actuator control unit 5270 is configured to adjust the actuator 67 in accordance with a command from the CPU 5210, the above-described color printing process or single color printing process can be selectively executed by issuing an appropriate command from the CPU 5210. . Further, as described above, in the present embodiment, when the color roller separation operation is executed, the color guide separation operation is always executed. Therefore, when the color belt separation operation is executed, the color guide separation operation is always executed.

  Further, when the arc surface of the monochrome frame cam 73 is separated from the monochrome roller support frame 71 by rotating the cam rotation shaft 63 from the state of FIG. 4, the monochrome roller separation operation is executed as shown in FIG. Therefore, all the primary transfer rollers are separated from the photosensitive drums 21 facing each other. At this time, since the tension roller 55 moves in the tensioning direction of the transfer belt 53 in conjunction with the single color roller separation operation, tension is applied to the transfer belt 53. Therefore, the image forming station K also includes the transfer belt 53. It is separated from the photosensitive drum 21 (monochromatic belt separating operation). Thus, in this embodiment, the tension roller 55 functions as the “belt separation means” of the present invention. Further, as described above, when the single color roller separation operation is executed, the single color guide separation operation is always executed. Therefore, when the monochrome belt separation operation is executed, the monochrome guide separation operation is always executed. Furthermore, as described above, in the present embodiment, the arc surface of the color frame cam 65 overlaps the arc surface of the monochrome frame cam 73 and is shorter than the arc surface of the monochrome frame cam 73. As a result, the color belt separation operation is always executed when the monochrome belt separation operation is executed. Therefore, in the present embodiment, the transfer belt 53 can be separated from all the photosensitive drums 21 included in the image forming stations Y, M, C, and K by performing the single color belt separation operation. The neutralization unit 19 can be separated from the photosensitive drum 21 facing each other.

  The sheet feeding unit 11 includes a sheet feeding unit having a sheet feeding cassette 77 in which sheets S are stacked and held, and a pickup roller 79 that feeds the sheets S from the sheet feeding cassette 77 one by one. The sheet S fed from the sheet feeding unit by the pickup roller 79 is fed to the secondary transfer position TR2 after the feeding timing is adjusted by the registration roller pair 81.

  The secondary transfer roller 75 is provided so as to be able to come into contact with and separate from the transfer belt 53 and is driven to come into contact with and separate from a secondary transfer roller driving mechanism (not shown). The fixing unit 13 includes a heating roller 83 that incorporates a heating element such as a halogen heater and is rotatable, and a pressure roller 85 that presses and biases the heating roller 83. The image secondarily transferred to the sheet S is fixed to the sheet S at a predetermined temperature at a nip portion formed by the heating roller 83 and the pressure roller 85. In the present embodiment, the fixing unit 13 can be disposed in a space formed obliquely above the transfer belt 53, in other words, in a space opposite to the image forming unit 7 with respect to the transfer belt 16. The heat conduction to the electrical component box 5, the image forming unit 7, and the transfer belt 53 can be reduced, and the influence of temperature fluctuations on these can be reduced. Further, the sheet S thus subjected to the fixing process is conveyed to a paper discharge tray 4 provided on the upper surface portion of the housing body 3 via a paper discharge roller pair 87.

  Further, as shown in FIG. 2, the apparatus includes a display unit 540 that is controlled by the CPU 5110 of the main controller 510. This display unit 540 is configured by, for example, a liquid crystal display, and in accordance with a control command from the CPU 5110, the operation guidance to the user, the progress of the image forming operation, the occurrence of an abnormality in the apparatus, the replacement timing of any unit, etc. A predetermined message for notification is displayed.

  In FIG. 2, reference numeral 5130 denotes an image memory provided in the main controller 510 for storing an image given from an external device such as a host computer via the interface 5120. Reference numeral 5230 is a ROM for storing a calculation program executed by the CPU 5210, control data for controlling the engine unit EG, and the like. Reference numeral 5240 is a RAM for temporarily storing a calculation result in the CPU 5210 and other data. is there.

  Next, the attaching / detaching operation of the photosensitive cartridge in the image forming apparatus configured as described above will be described. Here, for example, when the photosensitive drum 21 in the photosensitive cartridge 17 reaches a predetermined lifetime, the photosensitive cartridge 17 needs to be replaced. In that case, first, it is necessary to take out the photosensitive cartridge 17 which is mounted on the apparatus main body and constitutes the image forming station. Therefore, in this image forming apparatus, the CPU 5110 instructs the display unit 540 to display the replacement request for the photosensitive member cartridge 17 and causes the display unit 540 to display the replacement request. When the operator who has confirmed this presses a specific button on an operation unit (not shown) provided adjacent to the display unit 540, for example, when the operator presses a specific button on the operation unit (not shown), the main controller 510 causes the engine controller 520 to perform photosensitivity. Body cartridge replacement is instructed. In this apparatus, by performing the single color roller separation operation as described above, all of the single color belt separation operation, the color belt separation operation, the single color guide separation operation, and the color guide separation operation can be performed. Therefore, the engine controller 520 that has received the photoconductor cartridge replacement command only outputs a single color roller separation command to the actuator controller 5270 regardless of whether the color printing processing is performed or after the single color printing processing is performed. The single color belt separation operation, the color belt separation operation, the single color guide separation operation, and the color guide separation operation are executed. That is, the CPU 5210 controls each part of the apparatus in accordance with a belt separation program stored in the ROM 5230 in advance to separate the transfer belt 53 from the image forming stations Y, M, C, and K, so that the photosensitive drum 21 and the transfer belt 53 are separated. While being spaced apart from each other, the charge eliminating portion 19 is separated from the photosensitive drum 21 (FIG. 5).

  When the separation operation of the transfer belt 53 and the charge removal unit 19 from the photoconductor drum 21 is completed, a display indicating that the photoconductor cartridge can be replaced by a command from the CPU 5110 of the main controller 510 is displayed on the display unit 540. Is done. In response to this, the operator removes the photoconductor cartridge to be replaced from the apparatus main body in a state where the transfer belt 53 and the charge removal unit 19 are separated from the photoconductor drum 21. Thereafter, a new photoconductor cartridge is mounted on the apparatus main body. Even at the time of mounting, the transfer belt 53 and the charge removal unit 19 are positioned at the separated positions, as in the stage of removing the photosensitive cartridge.

  As described above, in the present embodiment, a small-sized unit having the light guide 193 is adopted as the charge eliminating unit 19 and, when the photosensitive cartridge 17 is attached or detached, the respective charge eliminating units 19 must be opposed to each other. Separated from the body drum 21. Therefore, the photosensitive drum 21 and the light guide 193 facing the photosensitive drum 21 are prevented from interfering with each other when the photosensitive cartridge 17 is attached or detached, thereby preventing the photosensitive drum 21 or the light guide 193 from being damaged. As a result, the light irradiation surface 196 of the light guide 193 can be disposed close to and opposed to the photosensitive drum 21, and the light irradiated from the light irradiation surface 196 of the light guide 193 is blocked by other members or the like. The surface of the photosensitive drum 21 can be exposed without any problem. Therefore, the residual potential on the surface of the photosensitive drum 21 can be efficiently removed, and a good image can be formed. In addition, the image forming apparatus main body can be miniaturized.

  In the present embodiment, the monochromatic guide separation operation is accompanied by the monochromatic roller separation operation by fixing and supporting the neutralization unit 19 facing the photosensitive drum 21 of the image forming station K by the monochrome roller support frame 71. In addition, the neutralization unit 19 that faces each of the photosensitive drums 21 of the image forming stations Y, M, and C is fixedly supported by the color roller support frame 61, so that the color guide separation operation is performed. Is performed in accordance with the color roller separation operation. As a result, there is no need to separately provide a member for supporting the neutralization unit 19 included in the image forming stations Y, M, C, and K, a means for separating the neutralization unit 19 from the photosensitive drum 21 facing each other, and the like. Simplification is achieved.

  Further, in the present embodiment, the arc surface of the color frame cam 65 overlaps the arc surface of the monochrome frame cam 73 and is shorter than the arc surface of the monochrome frame cam 73. As a result, the color belt separation operation is always executed when the monochrome belt separation operation is executed. Therefore, in the present embodiment, regardless of whether the color printing process is performed or the monochrome printing process is performed, the monochrome belt separation operation is performed, so that the image forming stations Y, M, C, and K Since the transfer belt 53 can be separated from all of the photosensitive drums 21 and all the static eliminating sections 19 can be separated from the photosensitive drums 21 facing each other, the control means is simplified. .

(Second Embodiment)
FIG. 6 is a diagram showing another embodiment (second embodiment) of the present invention. In this embodiment, the color roller support frame 61 is fixedly supported by the color solenoid 47, and the monochrome roller support frame 71 is fixedly supported by the monochrome solenoid 48. Other configurations are the same as those in the first embodiment. FIG. 7 is a diagram illustrating an electrical configuration of the image forming apparatus according to the second embodiment. In the second embodiment, in order to control the color solenoid 47 and the monochrome solenoid 48 based on a command from the CPU 5210, the color solenoid control unit 5280 and the monochrome solenoid electrically connected to the color solenoid 47 are used. A monochrome solenoid control unit 5290 electrically connected to 48 is provided. Other electrical configurations are the same as those in the first embodiment.

  In the second embodiment, by adjusting the stroke of the color solenoid 47 in the direction D47, the primary transfer rollers 57Y, 57M, and 57C are separated from or contacted with the photosensitive drum 21 facing each other, and the color roller The neutralizing unit 19 fixedly supported by the support frame 61 is configured to be separated from or close to the photosensitive drum 21 facing each other. Further, by adjusting the stroke of the monochrome solenoid 48 in the direction of D48, the primary transfer roller 57K is separated from or brought into contact with the photosensitive drum 21 facing the primary transfer roller 57K, and the static elimination which is fixedly supported by the monochrome roller support frame 71. The part 19 is configured to be separated from or close to the photosensitive drum 21 facing the part 19. That is, in the embodiment shown in FIG. 6, the color solenoid 47 corresponds to the “color roller separation / contact means” in the present invention, and the monochrome solenoid 48 corresponds to the “single color roller separation / contact means” in the present invention. To do. When the primary transfer rollers 57Y, 57M, and 57C are separated from the photosensitive drums 21 facing each other (color roller separation operation), the tension is applied to the transfer belt 53 by the tension roller 55. Also, the primary transfer rollers 57Y, 57M and 57C are separated from the opposing photosensitive drum 21 (color belt separation operation). Furthermore, when the primary transfer roller 57K is separated from the photosensitive drum 21 facing the primary transfer roller 57K (single color roller separation operation), the tension is applied to the transfer belt 53 by the tension roller 55, so that the transfer belt 53 is also primary. The transfer roller 57K is separated from the opposing photosensitive drum 21 (monochromatic belt separation operation). Thus, also in the second embodiment, the tension roller 55 functions as the “belt separating means” in the present invention, as in the first embodiment. Therefore, also in the second embodiment, by adjusting the stroke of the color solenoid 47 in the direction D47, all the primary transfer rollers 47Y, 47M, 47C, and 47K are brought into contact with the photosensitive drum 21 facing each other. The color printing process performed in this manner and the monochrome printing process performed by bringing only the primary transfer roller 47K into contact with the opposing photosensitive drum 21 can be selectively executed.

  Also in the second embodiment, the static eliminator 19 is fixedly supported by the color roller support frame 61 and the monochrome roller support frame 71 as in the first embodiment. Therefore, when the color belt separating operation is executed, the charge eliminating portions 19 fixedly supported by the color roller support frame 61 are separated from the photosensitive drums 21 facing each other. Further, when the single color roller separation operation is executed, the neutralization unit 19 fixedly supported by the monochrome roller support frame 71 is separated from the photosensitive drum 21 facing it.

  Next, the operation for attaching and detaching the photosensitive cartridge after the color mode is executed in the image forming apparatus configured as described above will be described. In this apparatus, when the color mode is executed, the transfer belt 53 is in contact with the photosensitive drums 21 of the image forming stations Y, M, C, and K as shown in FIG. Here, for example, when the photosensitive drum 21 in the photosensitive cartridge reaches a predetermined life, the photosensitive cartridge needs to be replaced. In that case, first, it is necessary to take out the photosensitive cartridge that is mounted on the apparatus main body and constitutes the image forming station. Therefore, in this image forming apparatus, the CPU 5110 instructs the display unit 540 to display the replacement request for the photosensitive member cartridge 17 and causes the display unit 540 to display the replacement request. When the operator who has confirmed this presses a specific button on an operation unit (not shown) provided adjacent to the display unit 540, for example, when the operator presses a specific button on the operation unit (not shown), the main controller 510 causes the engine controller 520 to perform photosensitivity. Body cartridge replacement is instructed. In response to this, the engine controller 520 outputs a monochrome belt separation command to the monochrome solenoid control unit 5290 to execute the above-described monochrome belt separation operation, and outputs a color belt separation command to the color solenoid control unit 5280. Then, the above-described color belt separating operation is executed. Further, as described above, in the second embodiment as well, as in the first embodiment, the neutralization unit 19 included in each of the image forming stations Y, M, C, and K is fixed by the color roller support frame 61 and the monochrome roller support frame 71. It is supported. Therefore, when the single-color belt separation operation and the color belt separation operation are executed in accordance with a command from the engine controller 520, all the charge removal units 19 are separated from the photosensitive drums 21 facing each other. That is, the CPU 5210 controls each part of the apparatus in accordance with the color mode belt separation program stored in the ROM 5230 in advance to separate the transfer belt 53 from the image forming stations Y, M, C, K, and the photosensitive drum 21 and the transfer belt. 53 are separated from each other, and the charge eliminating unit 19 is separated from the photosensitive drum 21 (FIG. 8). In the above description, the single color belt separation operation and the color belt separation operation are performed almost simultaneously, but these timings do not have to be the same. In other words, the color belt separation operation may be performed after the single color belt separation operation or vice versa.

  When the separation operation of the transfer belt 53 and the charge removal unit 19 from the photoconductor drum 21 is completed, a display indicating that the photoconductor cartridge can be replaced by a command from the CPU 5110 of the main controller 510 is displayed on the display unit 540. Is done. In response to this, the operator removes the photoconductor cartridge to be replaced from the apparatus main body in a state where the transfer belt 53 and the charge removal unit 19 are separated from the photoconductor drum 21. Thereafter, a new photoconductor cartridge is mounted on the apparatus main body. Even at the time of mounting, the transfer belt 53 and the charge removal unit 19 are positioned at the separated positions, as in the stage of removing the photosensitive cartridge.

  Next, the operation for attaching and detaching the photosensitive cartridge after the monochrome mode is executed in the image forming apparatus configured as described above will be described. In this apparatus, when the monochrome mode is executed, the transfer belt 53 is separated from the image forming stations Y, M, and C and is in contact with only the photosensitive drum 21 of the image forming station K. Here, for example, when the photosensitive drum 21 in the photosensitive cartridge reaches a predetermined life, the photosensitive cartridge needs to be replaced. In that case, first, it is necessary to take out the photosensitive cartridge that is mounted on the apparatus main body and constitutes the image forming station. Therefore, in this image forming apparatus, the CPU 5110 instructs the display unit 540 to display a request for replacing the photosensitive cartridge, and causes the display unit 540 to display the replacement request. When the operator who has confirmed this presses a specific button on an operation unit (not shown) provided adjacent to the display unit 540, for example, when the operator presses a specific button on the operation unit (not shown), the main controller 510 causes the engine controller 520 to perform photosensitivity. Body cartridge replacement is instructed. In response to this, the engine controller 520 outputs only the monochrome belt separation command to the monochrome solenoid control unit 5290 because the transfer belt 53 is already separated from the image forming stations Y, M, and C, and the above-described monochrome controller. The belt separation operation is executed. Further, as described above, in the second embodiment as well, as in the first embodiment, the charge removal unit 19 included in each of the image forming stations Y, M, C, and K is fixed by the color roller support frame 61 and the monochrome roller support frame 71. It is supported. Therefore, in a state where the primary transfer rollers 57Y, 57M, 57C, and 57K are separated from all the photosensitive drums 21, all the static eliminating sections 19 are separated from the opposing photosensitive drums 21. That is, the CPU 5210 controls each part of the apparatus according to the belt separation program in the monochrome mode stored in advance in the ROM 5230 to separate the transfer belt 53 from the image forming station K, and separates the photosensitive drum 21 and the transfer belt 53 from each other. At the same time, the charge eliminating portion 19 is separated from the photosensitive drum 21 (FIG. 8).

  When the separation operation of the transfer belt 53 and the charge removal unit 19 from the photoconductor drum 21 is completed, a display indicating that the photoconductor cartridge can be replaced by a command from the CPU 5110 of the main controller 510 is displayed on the display unit 540. Is done. In response to this, the operator removes the photoconductor cartridge to be replaced from the apparatus main body in a state where the transfer belt 53 and the charge removal unit 19 are separated from the photoconductor drum 21. Thereafter, a new photoconductor cartridge is mounted on the apparatus main body. Even at the time of mounting, the transfer belt 53 and the charge removal unit 19 are positioned at the separated positions, as in the stage of removing the photosensitive cartridge.

  In such an image forming apparatus, the switching operation between the color mode and the single color mode can be executed by outputting a color mode command or a single color mode command from the CPU 5210 to the color solenoid control unit 5280. That is, when a color mode command is output after executing the single color mode, the color solenoid control unit 5280 adjusts the stroke of the color solenoid 47 so that the primary transfer rollers 57Y, 57M, and 57C sandwich the transfer belt 53. Each is brought into contact with the opposing photosensitive drum 21. As a result, the transfer belt 53 comes into contact with the image forming stations Y, M, and C. Conversely, when a single color mode command is output after execution of the color mode, the transfer belt 53 is separated from the image forming stations Y, M, and C by executing the same operation as the color belt separation operation described above. be able to.

  As described above, in the second embodiment, a small-sized unit having the light guide 193 is employed as the charge eliminating unit 19, and each charge eliminating unit 19 always faces each other when the photosensitive cartridge 17 is attached or detached. Separated from the photosensitive drum 21. Therefore, the photosensitive drum 21 and the light guide 193 facing the photosensitive drum 21 are prevented from interfering with each other when the photosensitive cartridge 17 is attached or detached, thereby preventing the photosensitive drum 21 or the light guide 193 from being damaged. As a result, the light irradiation surface 196 of the light guide 193 can be disposed close to and opposed to the photosensitive drum 21, and the light irradiated from the light irradiation surface 196 of the light guide 193 is blocked by other members or the like. The surface of the photosensitive drum 21 can be exposed without any problem. Therefore, the residual potential on the surface of the photosensitive drum 21 can be efficiently removed, and a good image can be formed. In addition, the image forming apparatus main body can be miniaturized.

  In the present embodiment, the static eliminator 19 facing the photosensitive drum 21 of the image forming station K is fixedly supported by the monochrome roller support frame 71, so that the static eliminator 19 of the static eliminator 19 is separated with the monochromatic roller separation operation. It realizes a monochromatic roller separating / contacting means for separating the photosensitive drum 21 from the opposing photosensitive drum 21, and also includes a neutralizing section 19 facing each of the photosensitive drums 21 included in the image forming stations Y, M, and C. By being fixedly supported by the color roller support frame 61, a color roller separating / contacting means for performing the separation from the photosensitive drum 21 facing each of the static eliminating portions 19 in accordance with the color roller separating operation is realized. Yes. As a result, there is no need to separately provide a frame for supporting the neutralization unit 19 included in the image forming stations Y, M, C, and K, a means for separating the neutralization unit 19 from the opposing photosensitive drum 21, and the like. Simplification is achieved.

(Third embodiment)
The present invention can be applied not only to an image forming apparatus that selectively executes color printing processing and single color printing processing, but also to an image forming apparatus that executes only color printing processing. FIG. 9 is an embodiment (third embodiment) of the present invention in an image forming apparatus that executes only color printing processing. In this embodiment, one support member 89 rotatably supports the primary transfer rollers 57Y, 57M, 57C, and 57K, and fixedly supports the charge eliminating unit 19 of the image forming stations Y, M, C, and K. is doing. The support member 89 is supported by the solenoid 91. Therefore, by adjusting the stroke of the solenoid 91, the primary transfer rollers 57Y, 57M, 57C, and 57K can be separated from or brought into contact with the opposing photosensitive members, and the image forming stations Y, M, C, and The opposing surface 196 of the static eliminating unit 19 possessed by K can be separated from or brought close to the photosensitive drum 21 facing each other. That is, in the third embodiment, the solenoid 91 corresponds to the “roller separating contact means” in the present invention. Further, when the stroke of the solenoid 91 is adjusted so that all the primary transfer rollers are separated from the photosensitive drums 21 facing each other, the tension roller 55 moves in the direction in which the transfer belt 53 is stretched, thereby transferring the transfer belt. Apply tension to 53. Therefore, the transfer belt 53 is also separated from all the photosensitive drums 21. Thus, also in the third embodiment, the tension roller 55 functions as the “belt separating means” in the present invention, as in the first and second embodiments. The configuration other than the roller separation contact means and the belt separation means is the same as in the above embodiment.

  Since the third embodiment is configured as described above, when the photosensitive cartridge 17 is attached or detached, the primary transfer rollers 57Y, 57M, 57C, and 57K are separated by the roller separation and contact means. Thus, the transfer belt 53 and the charge eliminating portion 19 that opposes each photoconductor can be separated from all the photoconductor drums 21 (FIG. 10). As described above, in the third embodiment, a small-sized unit equipped with the light guide 193 is adopted as the charge eliminating unit 19, and when the photosensitive cartridge 17 is attached or detached, the respective charge eliminating units 19 must be opposed to each other. Separated from the body drum 21. Therefore, the photosensitive drum 21 and the light guide 193 facing the photosensitive drum 21 are prevented from interfering with each other when the photosensitive cartridge 17 is attached or detached, thereby preventing the photosensitive drum 21 or the light guide 193 from being damaged. As a result, the light irradiation surface 196 of the light guide 193 can be disposed close to and opposed to the photosensitive drum 21, and the light irradiated from the light irradiation surface 196 of the light guide 193 is blocked by other members or the like. The surface of the photosensitive drum 21 can be exposed without any problem. Therefore, the residual potential on the surface of the photosensitive drum 21 can be efficiently removed, and a good image can be formed. In addition, the image forming apparatus main body can be miniaturized.

  Further, in the third embodiment, all the static eliminators 19 are fixedly supported by the support member 89, whereby the primary transfer rollers 57Y, 57M, 57C, and 57K are separated from the photosensitive drum 21 facing each other. Separation of the charge removal unit 19 from the photosensitive drum 21 is realized. As a result, there is no need to separately provide a frame for supporting the neutralization unit 19 included in the image forming stations Y, M, C, and K, a means for separating the neutralization unit 19 from the opposing photosensitive drum 21, and the like. Simplification is achieved.

  The present invention is not limited to the above-described embodiment, and various modifications other than those described above can be made without departing from the spirit of the present invention. For example, in the above three embodiments, the light emitting members 191 a and 191 b for static elimination are attached to both ends of the light guide 193, and the light guide 193 and the light emitting members 191 a and 191 b are integrally separated from the photosensitive drum 21. Although the light guide 193 and the light emitting members 191a and 191b are separated and the light emitting members 191a and 191b are fixedly arranged, only the light guide 193 is located with respect to the photosensitive drum 21. You may comprise so that it may space apart or adjoin. In this case, the moving mechanism for moving the light guide 193 corresponds to the “guide separating means” of the present invention. In addition, the light emitting members 191 a and 191 b may be configured such that the light emitting members 191 a and 191 b are separated from or close to the photosensitive drum 21 as the light guide 193 moves away or approaches. In this case, the moving mechanism for moving the light emitting members 191a and 191b corresponds to the “light emitting member separating means” of the present invention.

  Moreover, in the said embodiment, although the static elimination process is performed using two light emitting members, it is arbitrary about the number of light emitting members, a kind, arrangement | positioning position, etc., and the light which combined the light emitting member and the light guide. The present invention can be applied to all image forming apparatuses adopting a static elimination method.

1 is a diagram illustrating a first embodiment of an image forming apparatus according to the present invention. 1 is a block diagram illustrating an electrical configuration of an image forming apparatus. The figure which shows the structure of a static elimination part. The figure which shows the inside of an apparatus at the time of monochrome printing processing execution. FIG. 3 is a view showing the inside of the apparatus when a photosensitive cartridge is attached or detached. FIG. 5 is a diagram illustrating a second embodiment of an image forming apparatus according to the present invention. FIG. 9 is a block diagram illustrating an electrical configuration of an image forming apparatus according to a second embodiment. The figure which shows the inside of an apparatus at the time of the photoconductor cartridge attachment or detachment in 2nd Embodiment. FIG. 9 is a diagram illustrating a third embodiment of an image forming apparatus according to the invention. The figure which shows the inside of an apparatus at the time of the photoconductor cartridge attachment or detachment in 3rd Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Apparatus main body, 17 ... Photoconductor cartridge, 19 ... Static elimination part, 21 ... Photoconductor drum, 47 ... Color solenoid, 48 ... Monochrome solenoid, 53 ... Transfer belt, 55 ... Tension roller, 57Y, 57M, 57C, 57K: primary transfer roller, 59: color rotation shaft, 61: color roller support frame, 63: cam rotation shaft, 65: cam for color frame, 67: actuator, 69: monochrome rotation shaft, 71: monochrome roller support Frame, 73 ... monochrome frame cam, support member ... 89, solenoid ... 91, 191a, 191b ... light emission member for static elimination, 193 ... light guide, 5270 ... actuator controller, 5280 ... color solenoid controller, 5290 ... monochrome Solenoid controller, Y, M, C, K ... Image forming station

Claims (7)

A plurality of image forming stations that form toner images of different colors on the surface of the respective photoreceptors are arranged side by side in the moving direction of the transfer belt, and the toner images formed on the surfaces of the plurality of photoreceptors are arranged. In an image forming apparatus for forming a color image by superimposing and transferring on the surface of the transfer belt,
Each of the plurality of image forming stations includes a photosensitive member cartridge that is detachable from the apparatus main body while holding the photosensitive member included therein, a light-emitting member that discharges light, and the photosensitive member cartridge. A neutralization unit comprising a light guide having a facing surface facing the photoconductor in a state of being attached to the light guide and irradiating light emitted from the light-emitting light-emitting member to the surface of the photoconductor through the facing surface. Have
A plurality of primary transfer rollers disposed one-on-one facing each of the plurality of image forming stations;
A support member that rotatably supports the plurality of primary transfer rollers and fixedly supports the plurality of light guides;
The support member is moved so that the plurality of primary transfer rollers are separated from or abutted by the image forming stations facing each other with the transfer belt interposed therebetween, and the plurality of light guides are separated from the photoreceptors facing each other. Roller separation contact means for separating or approaching; and
An image forming apparatus, further comprising: a belt separating unit that separates the transfer belt from the plurality of image forming stations in conjunction with the separating operation of the plurality of primary transfer rollers by the roller separating and contacting unit. . A plurality of image forming stations that form toner images of different colors on the surface of the respective photoreceptors are arranged side by side in the moving direction of the transfer belt, and the toner images formed on the surfaces of the plurality of photoreceptors are A color mode in which a color image is formed by superimposing and transferring on the surface of the transfer belt, and only the toner image formed on the surface of the photoreceptor of the specific image forming station among the plurality of image forming stations. In an image forming apparatus that selectively executes a single color mode for forming a single color image by transferring to
Each of the plurality of image forming stations includes a photosensitive member cartridge that is detachable from the apparatus main body while holding the photosensitive member included therein, a light-emitting member that discharges light, and the photosensitive member cartridge. A neutralization unit comprising: a light guide that has a facing surface facing the surface of the photoconductor in a state of being mounted on the light guide and irradiates the surface of the photoconductor through the facing surface with light emitted from the light-emitting member for neutralization; Have
A primary transfer roller for single color disposed opposite to the specific image forming station;
A plurality of primary transfer rollers for color arranged in a one-to-one relationship with each of all the image forming stations except the specific image forming station among the plurality of image forming stations;
A monochromatic support member that rotatably supports the monochromatic primary transfer roller, and fixedly supports the light guide of the specific image forming station;
A color that rotatably supports the plurality of primary color transfer rollers for color and fixedly supports the plurality of light guides of all the image forming stations other than the specific image forming station among the plurality of image forming stations. A supporting member;
The single color support member is moved so that the single color primary transfer roller is separated or brought into contact with the specific image forming station with the transfer belt interposed therebetween, and the light guide fixedly supported by the single color support member serves as the light guide. Single color roller separating and contacting means for separating or approaching from the opposing photoconductor;
The color support member is moved so that all of the plurality of color primary transfer rollers are separated or abutted against the image forming station facing each other with the transfer belt interposed therebetween, and the color support member is fixed. A color roller separating / contacting means for separating or approaching the plurality of light guides to be supported from or facing each other;
The transfer belt is separated from the specific image forming station in conjunction with the separation operation of the primary transfer roller for single color by the single color roller separation and contact means, and the plurality of colors by the color roller separation and contact means. Belt separating means for separating the transfer belt from all the image forming stations except the specific image forming station among the plurality of image forming stations in conjunction with the separating operation of the primary transfer roller. An image forming apparatus.   If necessary, after the color mode is executed, the single color primary transfer roller is separated from the specific image forming station by the single color roller separation / contact unit, and the plurality of colors are formed by the color roller separation / contact unit. The image forming apparatus according to claim 2, wherein each of the primary transfer rollers for use is separated from the image forming station facing each other.   4. The image forming apparatus according to claim 2, wherein, when the single color mode is executed, the plurality of color primary transfer rollers are separated from the opposed image forming stations by the color separating and contacting unit. 5.   The image forming apparatus according to claim 4, wherein the monochrome primary transfer roller is separated from the specific image forming station by the monochrome roller separating and contacting unit as necessary after execution of the monochrome mode.   6. The light emitting member separating unit according to claim 1, further comprising: a light emitting member separating unit that separates the light-emitting light-emitting member from the photosensitive member as the light guide is separated from the photosensitive member in each of the plurality of image forming stations. The image forming apparatus described.   The discharge light emitting member is integrally attached to the light guide in each of the plurality of image forming stations, and the discharge light emitting member is separated from the photoconductor as the light guide is separated from the photoconductor. 6. The image forming apparatus according to any one of items 5 to 5.

Images