JP2006227071A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a photosensitive drum and a static eliminating portion having a light guide from interfering with each other during a mounting / demounting operation of a photosensitive cartridge, and to dispose the light guide in close proximity to the photosensitive drum. Therefore, an image forming apparatus capable of efficiently removing a residual potential on the surface of a photosensitive drum and forming a good image is provided.
In an image forming apparatus that selectively executes a color mode and a monochromatic mode, the transfer belt 53 is separated from an image forming station K that forms a monochromatic image, which is performed prior to attachment / detachment of a photosensitive cartridge 17. Thus, the static elimination unit 19 having a light guide is configured to be separated from the photosensitive drum 21. Accordingly, it is possible to prevent the photosensitive drum 21 and the light guide from interfering with each other when the photosensitive cartridge is attached and detached, and the light guide can be disposed close to and opposed to the photosensitive drum 21.
[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-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.

  In the present invention, a plurality of image forming stations for forming toner images of different colors on the respective photoreceptors are arranged along the moving direction of the transfer belt, and the toner images on the plurality of photoreceptors are transferred. An image forming apparatus that selectively executes a color mode for forming a color image superimposed on a belt and a single color mode for forming a single color image only by a specific image forming station among a plurality of image forming stations, In order to achieve the above object, each of a plurality of image forming stations holds a photosensitive member, and is detachably provided with respect to the apparatus main body, a light-emitting light-emitting member that emits light, and the photosensitive member. When the body cartridge is mounted on the apparatus main body, it has a facing surface facing the photoconductor, and senses the light emitted from the light-emitting member for static elimination through the facing surface. A monochromatic belt separating means for separating the transfer belt from the specific image forming station, and a color belt for separating the transfer belt from the image forming station excluding the specific image forming station. The image forming apparatus further includes a separating unit, and a guide separating unit that separates the opposing surfaces of the plurality of light guides from the opposing photoconductor in accordance with the separating operation of the transfer belt by the single color belt separating unit.

  In the image forming apparatus configured as described above, the transfer belt is separated from the specific image forming station by the single color belt separating unit (monochromatic belt separating operation), and the image excluding the specific image forming station by the color belt separating unit. By separating the transfer belt from the forming station (color belt separating operation), the transfer belt can be separated from all the image forming stations. Further, according to the separation operation of the transfer belt by the single color belt separation means, all of the light guides arranged facing the photoconductor among the members constituting the static elimination unit are separated from the photoconductors facing each other. It is composed. Therefore, when the transfer belt is separated from all the image forming stations prior to attaching or detaching the photosensitive member cartridge, all the light guides are separated from the photosensitive member, thereby preventing mutual interference between the photosensitive member and the light guide. The 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, after execution of the color mode, the separation of the transfer belt from the specific image forming station by the single color belt separating unit and the separation of the transfer belt from the image forming station excluding the specific image forming station by the color belt separating unit are performed. And may be configured to execute. 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 executing the belt separating operation and the color belt separating operation, the transfer belt is separated from all the image forming stations. Further, according to the separation operation of the transfer belt by the single color belt separation means, all of the light guides arranged facing the photoconductor among the members constituting the static elimination unit are separated from the photoconductors facing each other. It is composed. 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.

  In addition, when the monochrome mode is executed, the transfer belt is separated from the image forming station excluding the specific image forming station by the color belt separating means, and all of the plurality of light guides are respectively arranged to face the plurality of photosensitive members. You may do it. In such an image forming apparatus, after the single color mode is executed, the transfer belt is separated from the specific image forming station by the single color belt separating means as necessary, and all the light guides are respectively separated according to the separating operation. You may comprise so that it may space apart from the opposing photoreceptor.

  In the image forming apparatus configured as described above, when the single color mode is executed, the transfer belt is separated from the image forming station excluding the specific image forming station for forming a single color image. 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 performing the monochrome belt separation operation. Further, all the light guides are separated from the opposing photoconductors according to the belt separating operation. 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. Therefore, 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 light-emitting member 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.

  FIG. 1 is a diagram showing an 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 has a color mode in which four color toners (developers) of black (K), cyan (C), magenta (M) and yellow (Y) are superimposed to form a color image, and black (K) The image forming apparatus selectively executes a monochrome mode in which a monochrome image is formed using only 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” of the present invention. In the single color mode, the image forming station K forms a single color (black) image. Each of the image forming stations Y, M, C, and K is provided with a photosensitive drum 21 on which a toner image of each color is 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. A downstream side of the next transfer position TR1 is disposed to face the surface of the photosensitive drum 21. Further, the static elimination unit 19 is fixedly supported by the static elimination unit support frame 45. Further, the static eliminator support frame 45 is fixedly supported by a single color roller support member 71 connected to a single color solenoid 48.

  FIG. 3A is a diagram showing the configuration of the static eliminating unit 19 as viewed from the vertical direction with respect to the arrow DTR1 in the drawing which is substantially horizontal with 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 are rotatably supported on the color roller support frame 61. Further, the color roller support frame 61 can be moved by a color solenoid 47 in a direction substantially perpendicular to the arrow DTR1 in the drawing. As a result, the primary transfer rollers 57Y, 57M, and 57C can come into contact with the photosensitive drums 21 of the image forming stations Y, M, and C with the transfer belt 53 interposed therebetween.

  FIG. 4 is a diagram showing an internal state of the image forming apparatus when the primary transfer rollers 57Y, 57M, and 57C are separated from the photosensitive drums 21 of the image forming stations Y, M, and C, respectively. As shown in FIG. 4, when the primary transfer rollers 57Y, 57M, and 57C are separated from the image forming stations Y, M, and C, the tension is applied to the transfer belt 53 by the tension roller 55. 53 abuts only on the photosensitive drum 21 included in the image forming station K and is separated from the photosensitive drum 21 included in each of the image forming stations Y, M, and C (color belt separating operation). As described above, in this embodiment, the transfer belt 53 is separated from the image forming stations Y, M, and C by the color roller support frame 61, the color solenoid 47, and the tension roller 55. It functions as “belt separation means”.

  The color solenoid 47 is electrically connected to the color solenoid control unit 5260 (FIG. 2), and the stroke of the color solenoid 47 according to a signal from the color solenoid control unit 5260 corresponding to a command from the CPU 5210. Is configured to be adjusted. Accordingly, the transfer belt 53 can be separated or brought into contact with the image forming stations Y, M, and C by issuing an appropriate command from the CPU 5210.

  Further, the description will be continued with reference to FIG. The primary transfer roller 57K is rotatably supported by the monochromatic roller support member 71. Further, as described above, the monochromatic roller support member 71 can be moved by the monochromatic solenoid 48 in a direction substantially perpendicular to the arrow DTR1 in the drawing. Thus, the primary transfer roller 57K can come into contact with and come into contact with the photosensitive drum 21 of the image forming station K with the transfer belt 53 interposed therebetween.

  FIG. 5 is a diagram illustrating a state inside the image forming apparatus when the primary transfer roller K is separated from the photosensitive drum 21 included in the image forming station K in the state of FIG. As shown in FIG. 5, when the primary transfer roller 57K is separated from the image forming station K, the tension is applied to the transfer belt 53 by the tension roller 55. It separates from the body drum 21 (monochromatic belt separating operation). As described above, in this embodiment, the transfer belt 53 is separated from the image forming station K by the single color roller support member 71, the single color solenoid 48, and the tension roller 55, and these are the “monochromatic belt separation means” of the present invention. Is functioning as Furthermore, as described above, the monochromatic roller support member 71 fixedly supports the static elimination unit support frame 45 that fixes and supports all the static elimination units 19. Therefore, when the single color belt separation operation is executed, the light guides of all the charge removal units 19 are separated from the photosensitive drums 21 facing each other (guide separation operation). As described above, in this embodiment, the static elimination unit support frame 45, the single color roller support member 71, and the single color solenoid 48 function as the “guide separation unit” in the present invention.

  The monochrome solenoid 48 is electrically connected to the monochrome solenoid control unit 5270 (FIG. 2), and the stroke of the monochrome solenoid 48 is determined by a signal from the monochrome solenoid control unit 5270 corresponding to a command from the CPU 5210. Is configured to be adjusted. Accordingly, the transfer belt 53 can be separated or brought into contact with the image forming station K by issuing an appropriate command from the CPU 5210. Further, in accordance with such a separation and contact operation of the transfer belt 53, all the charge removal units 19 can be separated from or brought close to the respective photosensitive drums 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 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, as shown in FIG. 1, the transfer belt 53 contacts the photosensitive drums 21 of the image forming stations Y, M, C, and K to form the primary transfer position TR1. ing. 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 a single color belt separation command to the single color solenoid control unit 5270 to execute the above-described single color belt separation operation and guide separation operation, and the color solenoid control unit 5260 provides the color belt separation operation. A separation command is output to execute the above-described color belt separation operation. 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. 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.

  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, as shown in FIG. 4, the transfer belt 53 is separated from the image forming stations Y, M, and C, and contacts only with the photosensitive drum 21 of the image forming station K. Thus, the primary transfer position TR1 is formed. 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 single-color belt separation command to the single-color solenoid control unit 5270 because the transfer belt 53 is already separated from the image forming stations Y, M, and C. A belt separation operation and a guide separation operation are executed. 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 static elimination unit 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.

  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 5260. That is, when a color mode command is output after execution of the single color mode, the color solenoid control unit 5260 adjusts the stroke of the color solenoid, and the primary transfer rollers 57Y, 57M, and 57C are sandwiched by the transfer belt 53, respectively. Are 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 (FIG. 1). 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. (FIG. 4).

  In the present embodiment, each static eliminating unit 19 is arranged to face each of the photosensitive drums 21 of the image forming stations Y, M, and C even when the monochrome mode is executed. On the other hand, when the monochrome mode is executed, the image forming stations Y, M, and C do not perform image formation. Therefore, when the monochrome mode is executed, it is also conceivable that the charge eliminating units 19 facing the photosensitive drums 21 included in these are separated from the photosensitive drums 21 facing each other. For example, it is also possible to adopt a configuration in which these static eliminators are fixedly supported by the color roller support frame 61 and separated from the photosensitive drum 21 in accordance with the color belt separation operation. However, in the present embodiment, the static eliminator 19 is disposed to face the photosensitive drums 21 of the image forming stations Y, M, and C even when the monochrome mode is executed for the following reason.

  As described above, when the color mode is switched to the single color mode, the transfer belt 53 moves from a contact position with the photosensitive drum 21 included in each of the image forming stations Y, M, and C to a predetermined separation position ( FIG. 6). On the other hand, the surface of the transfer belt 53 includes a toner image before secondary transfer, toner remaining after secondary transfer, and the like. Therefore, when switching from the color mode to the single color mode, toner that has scattered from these toner images and residual toner exists in the region (DM53) that the transfer belt 53 has passed in the process of moving from the contact position to the separation position. There is a case. Therefore, as described above, the static eliminator 19 corresponding to the image forming stations Y, M, and C is fixedly supported by the color roller support frame 61, and the static eliminator 19 is separated from the photosensitive drum 21 along with the color belt separation operation. If the structure to be taken is taken, the static elimination part 19 will be spaced apart in this area | region, and the static elimination part 19 will be contaminated with a toner. Such contamination of the charge removal unit 19 causes a reduction in charge removal efficiency and becomes an obstacle to good image formation. Therefore, in the present embodiment, each static eliminating unit 19 is arranged to face each of the photosensitive drums 21 of the image forming stations Y, M, and C even when the monochrome mode is executed.

  As described above, in the present embodiment, a small-sized one having the light guide 193 is adopted as the charge removal unit 19 and when the photosensitive cartridge 17 is attached or detached, either after the monochrome mode is executed or after the color mode is executed. In this case, the static eliminators 19 are always separated from the photosensitive drums 21 facing each other. 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 this embodiment, the separation operation of the transfer belt 53 from the image forming station is made independent between the specific image forming station K and the other image forming stations Y, M, and C. Further, even when the transfer belt 53 is separated from the image forming stations Y, M, and C, the charge eliminating unit 19 in the image forming stations Y, M, and C is not moved, and the transfer belt 53 is separated from the specific image forming station K. All the static eliminating sections 19 are separated from the photosensitive drum 21 in accordance with the operation of separating the single color belts. For this reason, as described above, the toner contamination of the charge removal unit 19 can be effectively prevented. In addition, since all the static eliminators 19 are configured to move according to the single color belt separation operation, the control sequence is simplified compared to the case where the static eliminator 19 is controlled to be moved including the color belt separation operation. can do.

  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. In the above embodiment, both the static elimination unit support frame 45 and the primary transfer roller 57K are configured to be supported by the single color roller support member 71, and the single color belt separation operation and the guide separation operation are performed simultaneously. Yes. However, for example, as shown in FIG. 7, a static elimination solenoid 50 is provided separately from the single color solenoid 48 to support the static elimination support frame 45 by the static elimination solenoid 50 and the stroke of the static elimination solenoid 50 is increased. By adjusting, all of the static eliminators 19 may be separated from the photosensitive drums 21 facing each other independently of the primary transfer roller 57K. In this case, at the same time as the operation of separating the transfer belt 53 from the image forming station K by the single-color belt separating means, all the static eliminating sections 19 may be separated from the photosensitive drums 21 facing each other, or the transfer belt 53 is separated. After the operation, all the static eliminating sections 19 may be separated from the photosensitive drums 21 facing each other. Of course, each separation operation may be executed in the reverse order. In short, the separation operation of the static eliminating unit 19 may be executed in accordance with the transfer belt separation operation by the single color belt separation means. Further, the direction of the stroke of the neutralizing unit solenoid 50 does not need to be parallel to the direction of the stroke of the single color solenoid 48, for example, a photoconductor facing each of the neutralizing units 19 such as a direction perpendicular thereto. Any direction that separates from the drum 21 is acceptable.

  In the above-described embodiment, the light-emitting light-emitting members 191 a and 191 b are attached to both ends of the light guide 193 so that the light guide 193 and the light-emitting members 191 a and 191 b are integrally separated from or adjacent to 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 separated from the photosensitive drum 21. Or may be configured to be close to each other. 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.

  In the above embodiment, the image forming station K is the specific image forming station in the present invention, and a black image is formed when the monochromatic mode is executed. However, the specific image is not limited to black, and other images such as yellow and magenta are used. It may be a color. In the above embodiment, the image forming stations Y, M, C, and K are arranged in this order from the upstream side in the moving direction of the transfer belt 53. However, the arrangement of the image forming stations is limited to this order. is not. 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 showing an embodiment of an image forming apparatus according to the present invention. FIG. 2 is a block diagram showing an electrical configuration of the image forming apparatus in FIG. 1. The figure which shows the structure of the static elimination part of FIG. The figure which shows the state inside an apparatus at the time of color belt separation operation | movement execution. The figure which shows the state inside an apparatus at the time of belt separation operation | movement for a single color. The figure which shows the employment | foundation basis of a guide separation means. FIG. 5 is a diagram showing another embodiment of the image forming apparatus according to the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Apparatus main body, 17 ... Photoconductor cartridge, 19 ... Static elimination part, 21 ... Photoconductor drum, 45 ... Static elimination part support frame, 47 ... Color solenoid, 48 ... Single color solenoid, 53 ... Transfer belt, 55 ... Tension roller 57Y, 57M, 57C, 57K ... primary transfer roller, 61 ... color roller support frame, 71 ... single color roller support member, 191a, 191b ... light emission member for static elimination, 193 ... light guide, 5260 ... solenoid control unit for color, 5270: Monochromatic solenoid control unit, Y, M, C, K: Image forming station

Claims (6)

A plurality of image forming stations for forming toner images of different colors on the respective photoreceptors are arranged along the moving direction of the transfer belt, and the toner images on the plurality of photoreceptors are placed on the transfer belt. In an image forming apparatus that selectively executes a color mode for forming a color image by superimposing on and a monochrome mode for forming a monochrome image only by a specific image forming station among the plurality of image forming stations,
Each of the plurality of image forming stations includes a photosensitive member cartridge that is detachably attached to the apparatus main body while holding the photosensitive member, a light-emitting light-emitting member that emits light, and the photosensitive member cartridge. A neutralization unit including a light guide that has a facing surface facing the photoconductor in a state of being mounted on the light guide and guides light emitted from the light-emitting light-emitting member to the photoconductor through the facing surface. ,
A monochromatic belt separating means for separating the transfer belt from the specific image forming station;
A color belt separating means for separating the transfer belt from an image forming station excluding the specific image forming station;
The apparatus further comprises guide separation means for separating the plurality of light guides from the photoconductors facing each other, in accordance with the separation operation of the transfer belt by the single color belt separation means. Image forming apparatus.   After the color mode is executed, the transfer belt is separated from the specific image forming station by the monochromatic belt separating unit, and the image forming station is excluded from the specific image forming station by the color belt separating unit. The image forming apparatus according to claim 1, wherein the transfer belt is separated.   When the monochrome mode is executed, the transfer belt is separated from the image forming stations except the specific image forming station by the color belt separating means, and all of the plurality of light guides are respectively arranged to face the plurality of photosensitive members. The image forming apparatus according to claim 1 or 2.   After the monochrome mode is executed, the transfer belt is separated from the specific image forming station by the monochrome belt separating means as necessary, and the plurality of light guides are separated from the plurality of photoconductors according to the separation operation. The image forming apparatus according to claim 3.   5. The light emitting member separation 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. In each of the plurality of image forming stations, a static elimination light emitting member is integrally attached to the light guide, and the static elimination light emitting member is attached to the photosensitive member as the light guide is separated from the photosensitive member by the guide separation means. The image forming apparatus according to claim 1, wherein the image forming apparatus is separated from the image forming apparatus.

Images