JP2016090821A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus that can separate a moving body from an image carrier with a simple configuration that can be easily reduced in size.SOLUTION: An image forming apparatus includes: an image carrier; a moving body; a separation member that can move between a retreat position (first position) and an operation position (second position) to separate the moving body from the image carrier; rotatable driving means 30 for rotating the image carrier; a first drive transmission part that transmits a driving force from the driving means 30 to the image carrier; and a second drive transmission part that transmits the driving force from the driving means 30 to the separation member. The first drive transmission part rotates the image carrier through normal rotation of the driving means 30, and the second drive transmission part moves the separation member from a storage position to the operation position through reverse rotation of the driving means.SELECTED DRAWING: Figure 5

Description

  The present invention relates to an image forming apparatus using an electrophotographic system or an electrostatic recording system.

  Conventionally, for example, in an image forming apparatus using an electrophotographic system, a toner image formed on an electrophotographic photosensitive member (for example, a photosensitive drum) as an image carrier is transferred to a transfer material or transferred via an intermediate transfer member. Direct transfer to a transfer material carried on a material carrier is performed. The color image forming apparatus has a plurality of image forming units along the moving direction of the intermediate transfer member or the transfer material carrier, and the toner image formed by each image forming unit is placed on the intermediate transfer member or the transfer material carrier. There is a so-called tandem type in which transfer is performed so as to be superimposed on a supported transfer material. In this case, generally, four image forming portions for each color of yellow, magenta, cyan, and black are provided. An endless belt is widely used as a movable body that can move in contact with an image carrier, such as an intermediate transfer member or a transfer material carrier.

  Such an image forming apparatus can output a color image, but may also be used when outputting a monochrome image. For this reason, such an image forming apparatus may have a color image forming mode for outputting a color image and a monochrome image forming mode for outputting a monochrome image.

  In the black and white image forming mode, the image forming unit for forming the toner image may be only the black image forming unit, and the other image forming unit (hereinafter also referred to as “color image forming unit”) forms the toner image. do not have to. However, since the photosensitive drum of each image forming unit is usually arranged in contact with the moving body, there is a problem that when the rotation of the photosensitive drum stops, a friction load is increased on the moving body.

  On the other hand, it is conceivable that the toner image is formed only by the black image forming unit and the photosensitive drum is rotated (idle rotation) in the color image forming unit. However, in this case, there is a problem that the toner is not supplied onto the photosensitive drum in the color image forming unit, and the cleaning blade that comes into contact with the photosensitive drum may be swollen. In addition, the photosensitive drum may be rubbed with a cleaning blade even when no toner image is formed, thereby causing a problem that the life of the photosensitive drum is unnecessarily shortened. Further, in the case where the toner stirring member in the developing device is configured to rotate in synchronization with the photosensitive drum, if the stirring member is rotated (idle rotation) even though the toner is not consumed, the toner is charged. The characteristics may change, and the problem of poor development may occur.

  Therefore, in the monochrome image forming mode, it has been proposed to stop the photosensitive drum by making the photosensitive drum and the moving body non-contact in the color image forming section (Patent Document 1).

Japanese Patent Laid-Open No. 10-319664

  However, in the configuration described in Patent Document 1, the photosensitive drum and the moving body are used in the color image forming unit by swinging the swinging unit to which the support roller of the moving body configured by an endless belt is attached. And are separated. In this configuration, it is necessary to separately provide a cam member and a special driving unit for driving the cam member in order to separate the photosensitive drum of the color image forming unit and the moving body. Further, in this configuration, it is necessary to largely change the posture of the moving body by swinging the swinging unit to which the support roller of the moving body is attached, and the configuration for that is complicated or relatively wide for that purpose. I have to secure a moving space.

  As described above, in the configuration described in Patent Document 1, in order to separate the moving body from the photosensitive drum of the color image forming unit, a special driving unit is provided or the posture of the moving body is greatly changed. The structure is complicated and easy to increase in size, and the cost is also increased.

  Note that the case where the image forming apparatus has the color image forming mode and the black and white image forming mode has been described above as an example. However, when there is a monochromatic image formation mode for other colors, or when it is intended to provide a separation mechanism that separates the moving body from the image carrier in some or all of the image forming units for adjustment operations, maintenance operations, etc. A similar problem may arise.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an image forming apparatus capable of separating a moving body from an image carrier with a simple and easily downsized configuration.

  The above object is achieved by the image forming apparatus according to the present invention. In summary, the present invention provides a rotatable image carrier that carries a toner image, a movable image that is movable in contact with the image carrier, and carries and conveys a toner image transferred from the image carrier. Or a moving body that carries and conveys a transfer material onto which a toner image is transferred from the image carrier, and the movable body retreats from between the image carrier and the movable body so that the movable body contacts the image carrier. A first position that is allowed to move, and the movable body is arranged between the image carrier and the movable body, and urges the movable body in a direction away from the image carrier, thereby moving the movable body to the image carrier. A separation member movable between the second position and the second position for separating the image carrier, a rotatable drive means for rotating the image carrier, and a first force for transmitting a driving force from the drive means to the image carrier. A second drive transmission portion and a second drive force transmitting the driving force from the drive means to the separation member. A drive transmission portion, wherein the first drive transmission portion transmits a driving force from the driving means rotating in a first direction to the image carrier to rotate the image carrier, and The transmission of the drive from the drive means rotating in the second direction opposite to the first direction to the image carrier is canceled, and the second drive transmission unit rotates in the second direction. The driving force from the driving means is transmitted to the spacing member to move the spacing member from the first position to the second position, and the driving force from the driving means that rotates in the first direction is applied to the spacing member. The image forming apparatus is characterized in that the separation member is transmitted to the separation member to move the separation member from the second position to the first position.

  According to the present invention, the moving body can be separated from the image carrier with a simple and easy-to-size configuration.

1 is a schematic cross-sectional configuration diagram of an image forming apparatus. It is a perspective view of a drum unit. It is a perspective view of a separation member. It is a perspective view of a drum drive part. It is a perspective view of a drum drive part. It is a schematic diagram which shows operation | movement of a separation member. 2 is a schematic control block diagram of a main part of the image forming apparatus. FIG. It is a flowchart for demonstrating switching operation | movement of a separation mechanism. It is a perspective view of the other example of a drum unit. It is a schematic sectional block diagram of the other example of an image forming apparatus.

  The image forming apparatus according to the present invention will be described below in more detail with reference to the drawings.

[Example 1]
1. 1 is a schematic cross-sectional configuration diagram of an image forming apparatus 100 according to an embodiment of the present invention. The image forming apparatus 100 according to the present exemplary embodiment is a tandem type color image forming apparatus that employs an intermediate transfer method capable of forming a full color image using an electrophotographic method.

  The image forming apparatus 100 includes first, second, third, and third images that form yellow (Y), magenta (M), cyan (C), and black (K) images as a plurality of image forming units, respectively. 4 image forming units (stations) PY, PM, PC, PK. These four image forming portions PY, PM, PC, and PK are arranged in one row. In this embodiment, the basic configurations and operations of the image forming units PY, PM, PC, and PK are substantially the same except that the color of the toner to be used is different. Therefore, hereinafter, unless there is a particular need for distinction, Y, M, C, and K at the end of a symbol indicating an element for any color will be omitted, and the element will be described generally.

  In each image forming portion P, a photosensitive drum 1 that is a drum-type (cylindrical) electrophotographic photosensitive member (photosensitive member) as a rotatable image carrier that supports a toner image is disposed. The photosensitive drum 1 is rotationally driven in the direction of arrow R1 in the figure. Around the photosensitive drum 1, the following devices are arranged in order along the rotation direction. First, a charger 2 as a charging unit is arranged. Next, an exposure device (laser scanner) 3 as an exposure unit is arranged. Next, a developing device 4 as a developing unit is arranged. Next, a primary transfer roller 5 which is a roller-shaped primary transfer member as a primary transfer means is disposed. Next, a drum cleaning device 6 as a photosensitive member cleaning unit is disposed.

  Further, the image forming apparatus 100 is formed by an endless belt as an intermediate transfer member disposed to face the photosensitive drums 1Y, 1M, 1C, and 1K of the image forming units PY, PM, PC, and PK. And an intermediate transfer belt 9. The intermediate transfer belt 9 is an example of a moving body that can move in contact with the photosensitive drum 1 and carries and conveys a toner image transferred from the photosensitive drum 1. The intermediate transfer belt 9 is wound around a driving roller 12, a push-up roller 14, a tension roller 13, and a secondary transfer counter roller 10 as a plurality of support rollers. The intermediate transfer belt 9 is stretched around the plurality of support rollers in a state in which a predetermined tension is applied by urging the tension roller 13 from the inner peripheral surface side to the outer peripheral surface side. The intermediate transfer belt 9 rotates (circulates) in the direction of the arrow R2 in the figure when the drive roller 12 is rotationally driven by a drive unit coupled to the drive roller 12. On the inner peripheral surface (back surface) side of the intermediate transfer belt 9, the primary transfer rollers 5Y, 5M, 5C, and 5K described above are disposed at positions facing the photosensitive drums 1Y, 1M, 1C, and 1K. The primary transfer roller 5 is urged (pressed) toward the photosensitive drum 1 via the intermediate transfer belt 9 by a pressing spring 8 (see FIG. 6A) as an urging means, and the intermediate transfer belt 9 and the photosensitive drum 1 are photosensitive. A primary transfer portion (primary transfer nip) T1 in contact with the drum 1 is formed. The primary transfer roller 5 rotates following the movement of the intermediate transfer belt 9. Further, on the outer peripheral surface (front surface) side of the intermediate transfer belt 9, a secondary transfer roller 11 that is a roller-like secondary transfer member as a secondary transfer unit is disposed at a position facing the secondary transfer counter roller 10. ing. The secondary transfer roller 11 is urged (pressed) toward the secondary transfer counter roller 10 via the intermediate transfer belt 9, and a secondary transfer portion (secondary transfer portion) in which the intermediate transfer belt 9 and the secondary transfer roller 11 are in contact with each other. (Next transfer nip) T2 is formed. Further, on the outer peripheral surface side of the intermediate transfer belt 9, a belt cleaning device 19 as an intermediate transfer member cleaning unit is disposed at a position facing the driving roller 12.

  In addition, the image forming apparatus 100 includes a feeding unit for the transfer material S, a fixing device 25 as a fixing unit for fixing the toner image on the transfer material S, and the like.

  The image forming operation will be described taking a case where a full color image is formed as an example. When the image forming operation is started, the outer peripheral surface (surface) of the rotationally driven photosensitive drum 1 is uniformly charged by the charger 2. The charged photosensitive drum 1 is irradiated with laser light corresponding to image information from the exposure device 3, whereby an electrostatic latent image (electrostatic image) is formed on the surface thereof. The electrostatic latent image formed on the surface of the photosensitive drum 1 is supplied with toner by the developing device 4 and developed (visualized) as a toner image.

  In this embodiment, the developing device 4 uses a two-component developer that is mainly a mixture of non-magnetic toner particles (toner) and magnetic carrier particles (carrier) as the developer. The developing device 4 includes a developing container 4a for storing a developer, a developing sleeve 4b as a developer carrying member disposed in an opening facing the photosensitive drum 1 of the developing container 4a, and the developer in the developing container 4a. And a stirring member 4c for stirring and transporting. The developer in the developing container 4a is conveyed while being stirred by the rotating stirring member 4c, and is supplied to the rotating developing sleeve 4a. The developing sleeve 4a has a magnet roller (not shown) in its hollow portion, and the developer is carried on the developing sleeve 4a by the magnetic force generated by the magnet roller. The developer carried on the developing sleeve 4a is transported to the opposite portion (developing position) between the developing sleeve 4a and the photosensitive drum 1 by the rotation of the developing sleeve 4a, and forms a magnetic brush that rises due to the magnetic force generated by the magnet roller. To do. Then, toner is supplied to the surface of the photosensitive drum 1 in accordance with the electrostatic latent image on the photosensitive drum 1 from the magnetic brush that is in contact with or close to the surface of the photosensitive drum 1 at the development position, and the electrostatic latent image becomes a toner image. As developed. At this time, a developing voltage (developing bias) is applied to the developing sleeve 4a. The developing sleeve 4a is configured to be able to apply a high voltage of several kV. In this embodiment, a toner image is formed by image portion exposure and reversal development. That is, the exposed portion on the photosensitive drum 1 where the absolute value of the potential is lowered by being exposed after being uniformly charged is charged to the same polarity (negative polarity in this embodiment) as the charging polarity of the photosensitive drum 1. Adhered toner adheres. In this embodiment, in each image forming unit P, the developing sleeve 4a and the stirring member 4c of the developing device 4 are driven to rotate in synchronization with the photosensitive drum 1 being rotated as will be described in detail later. It has become.

  The toner image on the photosensitive drum 1 is transferred (primary transfer) onto the rotating intermediate transfer belt 9 by the action of the primary transfer roller 5 in the primary transfer portion T1. At this time, the primary transfer roller 5 is applied with a primary transfer voltage (primary transfer bias) having a polarity (positive polarity in this embodiment) opposite to the charging polarity (normal charging polarity) of the toner during development. The primary transfer roller 5 is configured to be able to apply a high voltage of several kV. When forming a full-color image, each color toner image formed on each photosensitive drum 1 in each image forming unit PY, PM, PC, PK as described above is sequentially transferred onto the intermediate transfer belt 9 in each primary transfer unit T1. The primary transfer is performed so as to overlap.

  On the other hand, a transfer material S such as a sheet of paper or a synthetic resin is sent out from the transfer material storage 20 by a feeding roller 21 and a conveying roller 22, and the timing is matched with the toner image on the intermediate transfer belt 9 by a registration roller 23. It is conveyed to the secondary transfer portion T2. The toner image on the intermediate transfer belt 9 is transferred between the intermediate transfer belt 9 and the secondary transfer roller 11 by the action of the secondary transfer roller 11 on the transfer material S in the secondary transfer portion T2. (Secondary transfer). At this time, a secondary transfer voltage (secondary transfer bias) having a polarity (positive in this embodiment) opposite to the normal charging polarity of the toner is applied to the secondary transfer roller 11. The secondary transfer roller 11 is configured to be able to apply a high voltage of several kV. At the time of forming a full-color image, the toner images formed by superimposing four color toner images on the intermediate transfer belt 9 are secondarily transferred onto the transfer material S at once.

  The transfer material S on which the toner image is formed is conveyed to the fixing device 25 and heated and pressed at the fixing nip between the fixing roller 25a and the pressure roller 25b, so that the toner image is fixed thereon. (Fixed). Thereafter, the transfer material S is discharged onto a tray (not shown) outside the apparatus main body 110 of the image forming apparatus 100.

  Deposits such as toner (primary transfer residual toner) remaining on the surface of the photosensitive drum 1 after the primary transfer step are removed from the photosensitive drum 1 by the drum cleaning device 6 and collected. The drum cleaning device 6 scrapes off deposits such as primary transfer residual toner from the surface of the rotating photosensitive drum 1 by a cleaning blade 6 a as a cleaning member disposed in contact with the photosensitive drum 1. The cleaning blade 6 a is attached in a direction (counter direction) facing the rotation direction of the photosensitive drum 1. Further, deposits such as toner (secondary transfer residual toner) remaining on the surface of the intermediate transfer belt 9 after the secondary transfer process are removed from the intermediate transfer belt 9 by the belt cleaning device 19 and collected.

  In this embodiment, in each of the image forming units PY, PM, PC, and PK, the photosensitive drum 1 and the drum cleaning device 6 are integrated by a frame body (support body) 7a to constitute a drum unit 7 ( (See FIG. 2). The drum unit 7 can be integrally attached to and detached from the apparatus main body 110. In the present embodiment, the drum unit 7 can be attached to the apparatus main body 110 so as to be removed from the apparatus main body 110 so as to be pulled out to the front side of the apparatus main body 110 corresponding to the front side of the paper in FIG. It is like that. A drum driving unit 120 (see FIG. 4), which will be described later, is provided on the back side of the apparatus main body 110 in the mounting direction of the drum unit 7 corresponding to the back side of the sheet of FIG. In the present embodiment, the photosensitive drums 1 of the image forming units PY, PM, PC, and PK are independently driven to rotate by drum driving units 120 that are provided independently.

2. Image Forming Mode The image forming apparatus 100 according to the present exemplary embodiment includes a color image forming mode (first image forming mode) for forming a full color image, and a black and white image forming mode (second image forming mode) for forming a black and white image. Can be executed. In the color image forming mode, toner images are formed in the image forming portions PY, PM, PC, and PK for yellow, magenta, cyan, and black as described above, and the toner images are transferred to the intermediate transfer belt 9. Is transcribed. On the other hand, in the black-and-white image forming mode, the toner image is not formed in the color image forming portions PY, PM, and PC, and the toner image is formed only in the black image forming portion PK. The image is transferred to the intermediate transfer belt 9.

  As described above, when the photosensitive drum 1 is stopped in the color image forming unit in the black and white image forming mode, if the intermediate transfer belt 9 is in contact with the photosensitive drum 1, the friction load on the intermediate transfer belt 9 is increased. Increase. On the other hand, when the photosensitive drum 1 is rotated (idly rotated) in the color image forming unit, the cleaning blade may be bent, the life of the photosensitive drum 1 may be shortened, and the toner charging characteristics may be changed.

  Therefore, in this embodiment, in the monochrome image forming mode, the intermediate transfer belt 9 is separated from the photosensitive drum 1 in the color image forming unit, and the rotation of the photosensitive drum 1 is stopped.

  Here, as in Patent Document 1, a special driving unit is provided to largely separate the intermediate transfer belt 9 from the photosensitive drum 1 of the color image forming unit, or the posture of the intermediate transfer belt 9 is greatly changed. As a result, the structure becomes complicated and large, and the cost tends to increase. Further, in this configuration, the binding force on the intermediate transfer belt 9 in the black and white image forming mode is significantly lower than that in the color image forming mode. Therefore, in the black and white image forming mode, for example, when the transfer material S enters the secondary transfer portion T2, the speed fluctuation of the intermediate transfer belt 9 increases, and image degradation such as image streak may occur.

  Therefore, it is desirable to have a configuration that does not require special driving means for separating the intermediate transfer belt 9 from the photosensitive drum 1 of the color image forming unit. In addition, a configuration in which the posture of the intermediate transfer belt 9 does not need to be changed greatly in order to separate the intermediate transfer belt 9 from the photosensitive drum 1 of the color image forming unit is also desired. Further, a configuration is desired in which the change in the restraining force on the intermediate transfer belt 9 between the color image formation mode and the black and white image formation mode is sufficiently small so that the intermediate transfer belt 9 can travel stably against disturbance.

3. Next, a separation mechanism for separating the intermediate transfer belt 9 from the photosensitive drum 1 in this embodiment will be described. In this embodiment, the separation mechanism is provided in the color image forming units PY, PM, and PC among the four image forming units. However, in this embodiment, the separation member described later also functions as a protection member for the photosensitive drum 1 when the drum unit 7 is taken out of the apparatus main body 110 as described later. Therefore, among the elements constituting the separation mechanism, elements such as a separation member described later provided in the drum unit 7 are also provided in the black image forming unit PK. Here, unless otherwise specified, a color image forming unit will be described as an example.

  In this embodiment, the separation mechanism is roughly configured as follows. That is, the drive is distributed from the drive train that drives the photosensitive drum 1, and the rotatable roller member of the separation member enters (inserts) between the photosensitive drum 1 and the intermediate transfer belt 9 in the primary transfer portion T <b> 1. The roller member is biased (pressed) toward the primary transfer roller 5 via the intermediate transfer belt 9, and the intermediate transfer belt 9 is moved while the intermediate transfer belt 9 is sandwiched between the roller members. Rotates in conjunction with. This will be described in more detail below.

  FIG. 2 is an external perspective view of the drum unit 7 as viewed from the drum driving unit 120 (FIG. 4). The photosensitive drum 1 is rotatably supported on the frame 7 a of the drum unit 7. Further, a separation member 70 is movably supported on the frame body 7 a of the drum unit 7.

  3A and 3B are perspective views showing the spacing member 70 in more detail. As shown in FIG. 3A, the separation member 70 has a support portion 71 formed by deforming a metal shaft in this embodiment. The support portion 71 has a main portion 71a extending in a direction along the longitudinal direction (rotation axis direction) of the photosensitive drum 1 and a direction substantially orthogonal to the axis of the main portion 71a at both ends in the longitudinal direction of the main portion 71a. And an extending mounting portion 71b. A connecting portion 71c for connecting the separating member 70 to the frame body 7a is formed at the end of the mounting portion 71b opposite to the main portion 71a on both ends in the longitudinal direction of the photosensitive drum 1. . Further, as shown in FIG. 3B, the separating member 70 includes a roller member 72 as a rotating member that is rotatably attached to the support portion 71. The roller member 72 is attached to both ends in the longitudinal direction of the main portion 71a corresponding to the outside (non-image forming region) of the image forming region (region in which a toner image can be formed) in the longitudinal direction of the photosensitive drum 1. It has been. Further, as shown in FIG. 3B, the separation member 70 includes a cover member 73 attached to the support portion 71 so as to cover a part of the roller member 72 in the circumferential direction outside the roller member 72. The cover member 73 covers a part of the surface on the photosensitive drum 1 side in the circumferential direction of the roller member 72, and exposes the surface of the other part on the intermediate transfer belt 9 side in the circumferential direction of the roller member 72.

  As shown in FIG. 2, the separation member 70 includes a rack member 74 as an operation unit that operates the separation member 70. The rack member 74 is slidably attached to the side portion 7b of the frame 7a on the drum driving unit 120 side in the longitudinal direction of the photosensitive drum 1. One connecting portion 71 c formed on the support portion 71 is connected to the rack member 74. On the side opposite to the drum driving unit 120 in the longitudinal direction of the photosensitive drum 1, the other connecting portion 71 c formed on the support portion 71 is movably connected to the side portion 7 b of the frame body 7 a.

  Inside the apparatus main body 110, the rack member 74 is connected to a drive train branched from the drum drive train that drives the photosensitive drum 1, as will be described later. Thus, the separation member 70 is connected to the drive train branched from the drum drive train that drives the photosensitive drum 1 via the rack member 74. The rack member 74 moves in a direction approaching and moving away from the photosensitive drum 1 along a direction substantially orthogonal to the longitudinal direction of the photosensitive drum 1. The rack member 74 and the other elements of the separation member 70 are configured to move (interlock) together.

  The separation member 70 includes a first position (storage position) that allows the intermediate transfer belt 9 to contact the photosensitive drum 1, a second position (operation position) that separates the intermediate transfer belt 9 from the photosensitive drum 1, and Can be moved between. The separation member 70 is retracted from between the photosensitive drum 1 and the intermediate transfer belt 9 and separated from the intermediate transfer belt 9 when in the retracted position. Further, the separation member 70 is disposed between the photosensitive drum 1 and the intermediate transfer belt 9 when in the operating position, and urges the intermediate transfer belt 9 in a direction away from the photosensitive drum 1. In this embodiment, the separating member 70 has a roller member 72 that can rotate by following the movement of the intermediate transfer belt 9 in contact with the intermediate transfer belt 9 when the separating member 70 is in the operating position. In this embodiment, the separation member 70 includes a cover member 73 that is disposed between the roller member 72 and the photosensitive drum 1 and contacts the surface of the photosensitive drum 1 when in the operating position. In this embodiment, the cover member 73 contacts the surface of the photosensitive drum 1 in the non-image forming region at the end portion in the longitudinal direction of the photosensitive drum 1. That is, in this embodiment, when the separation member 70 is in the operating position, the main portion 71 a of the support portion 71, the roller member 72, and the cover member 73 of the separation member 70 are connected between the photosensitive drum 1 and the intermediate transfer belt 9. Arranged between.

  Thus, in the present embodiment, the support portion 71 of the separation member 70 supports the roller member 72 in a rotatable manner, supports the cover member 73 so as to cover the roller member 72, and is formed at the end. Are connected to the rack member 74. Therefore, the movement of the rack member 74 causes the separation member 70 to be taken in and out between the photosensitive drum 1 and the intermediate transfer belt 9 as follows. When the drive is input to the rack member 74, the separation member 70 is guided by guide portions 7 d (see FIG. 2) formed on the side portions 7 b of the frame bodies 7 a on both ends in the longitudinal direction of the photosensitive drum 1. Then, it enters (or retreats) between the photosensitive drum 1 and the intermediate transfer belt 9. When the separating member 70 enters (or retracts) between the photosensitive drum 1 and the intermediate transfer belt 9, the roller member 72 enters between the photosensitive drum 1 and the intermediate transfer belt 9 while rolling on the intermediate transfer belt 9. (Or evacuate). At this time, the cover member 73 provided outside the roller member 72 contacts the non-image forming area of the photosensitive drum 1 and enters (or retracts) between the photosensitive drum 1 and the intermediate transfer belt 9 while sliding. To do. 6A and 6B schematically show the state of the primary transfer portion T1 when the separating member 70 is in the retracted position and the operating position, respectively. In this embodiment, when the separation member 70 is disposed at the operating position, the roller member 72 contacts the primary transfer roller 5 via the intermediate transfer belt 9. Further, the separation member 70 pushes down the primary transfer roller 5 against the pressing force of the pressing spring 8 by the roller member 72 via the intermediate transfer belt 9. The separation member 70 separates the intermediate transfer belt 9 from the photosensitive drum 1 in a state where the intermediate transfer belt 9 is sandwiched between the separation member 70 and the primary transfer roller 5. That is, the primary transfer roller 5 sandwiches the intermediate transfer belt 9 with the photosensitive drum 1 when the separating member 70 is in the retracted position (FIG. 6A), and when the separating member 70 is in the operating position. The intermediate transfer belt 9 is sandwiched between the separation member 70 (FIG. 6B).

  Further, the side portion 7b of the frame 7a on the drum driving unit 120 side in the longitudinal direction of the photosensitive drum 1 is provided with an abutting portion 7c that abuts the rack member 74 when the separating member 70 is stored in the storage position. Yes. As a result, further movement of the separating member 70 in the direction from the operating position toward the retracted position is restricted.

  4 and 5 are perspective views illustrating the drum driving unit 120 of the photosensitive drum 1 provided in the apparatus main body 110 in a state where the drum unit 7 is mounted on the apparatus main body 110. FIG. In particular, FIG. 4 shows a state in which a drum drive motor 30 to be described later rotates (hereinafter also referred to as “forward rotation”) in a first direction that is a rotation direction during image formation. On the other hand, FIG. 5 shows a state in which a drum drive motor 30 to be described later rotates (hereinafter also referred to as “reverse rotation”) in a second direction which is a rotation direction opposite to the rotation direction during image formation. .

  The drum driving unit 120 includes a drum driving motor 30 that inputs driving to the photosensitive drum 1 as a rotatable driving unit that rotates the image carrier. In this embodiment, a stepping motor is used as the drum drive motor 30. The drum drive motor 30 is fixed to the support plate 31. Gear portions 32 a and 32 b are formed on both sides of the output shaft of the drum drive motor 30. One gear portion (drum side gear portion) 32 a of the drum drive motor 30 is connected to the drum drive gear 41. The drum drive gear 41 is disposed coaxially with the photosensitive drum shaft 16 connected to the photosensitive drum 1. A one-way clutch 42 (see FIG. 7) is inserted into the connecting portion between the drum drive gear 41 and the photosensitive drum shaft 16. As a result, as shown in FIG. 4, the drive from the drum drive motor 30 is transmitted to the photosensitive drum 1 only when the drum drive motor 30 rotates forward. When the drum drive motor 30 rotates in the forward direction, the drum drive gear 41, the flywheel 43 provided on the same axis as the drum drive gear 41, and the photosensitive drum 1 rotate in the arrow direction in FIG.

  On the other hand, the other gear portion (separation mechanism side gear portion) 32b of the drum drive motor 30 is connected to a separation drive gear train 61 (more specifically, the most upstream input gear 61a) that transmits drive to the separation member 70. ing. The separation drive gear train 61 (more specifically, the most downstream output gear 61b) is connected to the rack member 74 of the separation member 70. As shown in FIG. 5, in the separation drive gear train 61, when the drum drive motor 30 reverses, the rack member 74 moves in the direction of the arrow in FIG. 5, and the separation member 70 protrudes toward the primary transfer portion T1. That is, it is configured to move from the retracted position toward the operating position. When the rack member 74 moves, the flag 74a (see FIG. 7) provided on the rack member 74 also moves. Then, the stop position is detected by a photo sensor 90 (see FIG. 7) provided in the drum unit 7, and the drive is stopped. When the drum drive motor 30 rotates in the reverse direction, the drum drive gear 41 idles in the direction of the arrow in FIG. However, at this time, since the one-way clutch 42 is provided, the flywheel 43 and the photosensitive drum 1 provided coaxially with the drum drive gear 41 are stopped. As the separation member 70 enters the primary transfer portion T1, the cover member 73 of the separation member 70 moves in contact with the surface of the photosensitive drum 1, so that the photosensitive drum 1 is rotated in the rotation direction during image formation. Rotates in the opposite direction. However, at this time, the one-way clutch 42 is idled to prevent the drum drive motor 30 from being applied with a force in the direction opposite to the direction in which the output shaft rotates.

  Further, as shown in FIG. 4, the separation drive gear train 61 moves the rack member 74 in the direction of the arrow in FIG. 4 when the drum drive motor 30 rotates forward, and the separation member 70 is pulled out from the primary transfer portion T1. That is, it is configured to move from the operating position toward the retracted position. At this time, the rack member 74 moves in a direction to abut against the abutting portion 7c. A torque limiter 62 (see FIG. 7) is provided in the separation drive gear train 61 so that the drive is not transmitted from the drum drive motor 30 to the separation member 70 when the rack member 74 abuts against the abutting portion 7c. . This prevents the drum drive motor 30 from stepping out and the spacing member 70 from being destroyed. In addition, since the torque limiter is provided in the drive train, the load of the torque limiter always functions as a load for driving the photosensitive drum 1, and for example, the load fluctuation when the transfer material S enters the secondary transfer portion T2. Can be reduced.

  Here, in this embodiment, the separation member 70 is a protective member (supporting member) for the photosensitive drum 1 for improving workability when the drum unit 7 is removed from the apparatus main body 110 and the photosensitive drum 1 is replaced. It also has the function of That is, as shown in FIG. 2, for example, when the drum unit 7 is placed on the floor or table outside the apparatus main body 110, the separation member 70 is disposed at a position corresponding to the above-described operation position (second position). . The drum unit 7 is supported on the floor or the table by the bottom plate portion 7e of the frame body 7a and the roller member 72 of the separation member 70. Thereby, the surface of the photosensitive drum 1 is suppressed from being damaged. For this reason, in this embodiment, the separation member 70 can be taken in and out even outside the apparatus main body 110. The separation member 70 is connected to a lever (not shown) protruding outside the drum unit 7. In this embodiment, this lever is provided so as to protrude from the side portion 7b of the frame body 7a opposite to the drum driving portion 120 in the longitudinal direction of the photosensitive drum 1 corresponding to the back side of the paper surface of FIG. In order to perform the operation of inserting and removing the separation member 70 outside the apparatus main body 110, the lever is slid between a position corresponding to the storage position and the operation position. When the drum unit 7 is mounted on the apparatus main body 110, the separation member 70 is retracted to the storage position. Inside the apparatus main body 110, as described above, the separation member 70 is connected to the drive train branched from the drum drive train that drives the photosensitive drum 1 via the rack member 74.

  In the present embodiment, the drum drive gear 41, the one-way clutch 42, and the like constitute a first drive transmission unit 40 (see FIG. 7) that transmits the driving force from the drum drive motor 30 to the photosensitive drum 1. The drum drive motor 30 and the first drive transmission unit 40 constitute a drum drive mechanism 50 (see FIG. 7). The first drive transmission unit 40 transmits the driving force from the drum drive motor 30 that rotates in the first direction, which is the rotation direction during image formation, to the photosensitive drum 1 to rotate the photosensitive drum 1 in the rotation direction during image formation. Rotate to On the other hand, the first drive transmission unit 40 cancels the transmission of the drive from the drum drive motor 30 rotating in the second direction opposite to the first direction to the photosensitive drum 1.

  In the present embodiment, the second drive transmission unit 60 (see FIG. 7) that transmits the driving force from the drum drive motor 30 to the separation member 70 is configured by the separation drive gear train 61, the torque limiter 62, and the like. The drum drive motor 30, the second drive transmission unit 60, the separation member 70, the photo sensor 90, and the like constitute a separation mechanism 80. The second drive transmission unit 60 transmits the driving force from the drum drive motor 30 rotating in the second direction to the separation member 70 to move the separation member 70 from the retracted position (first position) to the operating position (first position). 2). On the other hand, the second drive transmission unit 40 transmits the driving force from the drum drive motor 30 rotating in the first direction to the separation member 70 to move the separation member 70 from the operating position (second position) to the storage position. Move to (first position).

4). Separation Operation Next, control for switching the separation mechanism 80 in accordance with the image forming mode will be described. FIG. 7 is a schematic control block diagram of control for switching the separation mechanism 80 in the present embodiment. FIG. 8 is a schematic control flowchart of control for switching the separation mechanism 80 in the present embodiment.

  In the present exemplary embodiment, a control unit 150 serving as a control unit provided in the image forming apparatus 100 comprehensively controls each unit of the image forming apparatus 100. The control unit 150 includes a CPU 151 that is a central element that performs arithmetic processing, a ROM 152 and a RAM 153 that are storage elements, and the like. The RAM 153 stores sensor detection results, calculation results, and the like, and the ROM 152 stores a control program, a previously obtained data table, and the like. Each control object in the image forming apparatus 100 is connected to the control unit 150. In relation to this embodiment, the control unit 150 includes a drum drive motor 30, a photo sensor 90, a belt drive motor 15 as a drive unit for the intermediate transfer belt 9, and an operation panel 130 as an operation unit for the apparatus main body 110. Etc. are connected. Note that the drum drive motor 30 is provided in each of the image forming units PY, PM, PC, and PK, but in FIG. 7, only the drum drive motor 30 of one image forming unit that is an image forming unit for color is used. Is shown.

  The control unit 150 can cause the image forming apparatus 100 to execute a series of image forming operations (jobs) that form and output an image on a single or a plurality of transfer materials P, which is started by one start instruction. . In addition, the control unit 150 functions as an execution unit that selectively executes a color image formation mode (first image formation mode) and a monochrome image formation mode (second image formation mode). Then, according to whether the job is a color image forming mode job or a monochrome image forming mode job, the control unit 150 causes the color image forming units PY, PM, and PC of the photosensitive drum 1 and the intermediate transfer belt 9 to be The state of contact or separation of is switched.

  First, when a job start signal is input (S101), the control unit 150 determines whether a color image formation mode is selected or a monochrome image formation mode is selected (S102). The monochrome image formation mode is selected by pressing a monochrome image formation mode selection button provided on the operation panel 130 operated by the operator, and the color image formation mode is selected when there is no particular operation. When the monochrome image output mode is selected, the intermediate transfer belt 9 is separated from the photosensitive drum 1 in the primary transfer portion T1 for color image forming portions PY, PM, and PC, and the color image forming portions PY, PM, and PC are set. The function of is stopped.

  When the control unit 150 determines that the black and white image forming mode is selected, the drum driving motor 30 is reversely rotated in the color image forming unit (S103), and the separation member 70 is protruded to the operating position. Then, the intermediate transfer belt 9 is separated (S104). At this time, due to the action of the one-way clutch 42, the drive is not transmitted to the photosensitive drum 1 and is stopped. Then, when it is detected by the photosensor 90 that the separation member 70 is disposed at the operating position, the control unit 150 stops the drum drive motor 30 and stops the movement of the separation member 70 (S105). Thereafter, the control unit 150 rotates the drum driving motor 30 of the black image forming unit PK in the normal direction to input the driving to the photosensitive drum 1 and rotates the belt driving motor 15 to input the driving to the intermediate transfer belt 9. (S106). Then, the control unit 150 starts image formation in the black image forming unit PK (S107). At this time, in the color image forming portions PY, PM, and PC, the intermediate transfer belt 9 is held between the roller member 72 of the separation member 70 and the primary transfer roller 5, and the roller member 72 is rotated while the intermediate transfer belt 9 is rotating. Also, it rotates following the movement of the intermediate transfer belt 9. Thereafter, when the image formation in the black image forming unit PK is completed (S108), the control unit 150 stops the drum drive motor 30 and the belt drive motor 15 of the black image forming unit PK (S109), and performs the job. Is terminated (S110).

  On the other hand, when the control unit 150 determines that the color image forming mode has been selected, the drum driving motors 30 of all the image forming units are rotated forward to input driving to the photosensitive drums 1 and the belt driving motor 15 is rotated. Then, driving is input to the intermediate transfer belt 9 (S111). At this time, in the color image forming portions PY, PM, and PC, the drive is transmitted to the separation member 70 as well. When the separation member 70 is in the operating position in the color image forming units PY, PM, and PC before the rotation of the drum drive motor 30 starts, the separation member 70 moves in the direction from the operation position toward the storage position. Retreated to the storage position. Then, driving is input to the separating member 70 until the rack member 74 abuts against the abutting portion 7c, and when the rack member 74 abuts against the abutting portion 7c, the torque limiter 62 is activated and the drive is not transmitted, and the separating member 70 stops. If the separation member 70 is already in the storage position in the color image forming portions PY, PM, and PC before the drum drive motor 30 starts to rotate, the rack member 74 hits the abutting portion 7c and the torque limiter. The separation member 70 does not move due to the operation of 62. Thereafter, the control unit 150 starts image formation in each image forming unit P (S112). Thereafter, when image formation in each image forming unit P is completed (S113), the control unit 150 stops the drum drive motor 30 and the belt drive motor 15 of all the image forming units P (S114), and ends the job. (S110).

  As described above, in this embodiment, the intermediate transfer belt 9 can be separated from the photosensitive drum 1 by using the drum drive motor 30 as a drive source. Therefore, it is not necessary to provide special driving means for separating the intermediate transfer belt 9 from the photosensitive drum 1. In addition, since the color image forming unit can be stopped in the monochrome image forming mode, it is possible to prevent the cleaning blade 6a from curling in the color image forming unit and the life of the photosensitive drum 1 from being shortened. In addition, since the agitating member 4c of the developing device 4 of the color image forming unit is not idly rotated in the black and white image forming mode, it is possible to suppress a change in the charging characteristics of the toner and to cause a problem of development failure. Can be suppressed.

  In this embodiment, since the intermediate transfer belt 9 is separated from the photosensitive drum 1 of the color image forming unit, it is not necessary to largely change the posture of the intermediate transfer belt 9. Therefore, it is not necessary to secure an extra space for that purpose, and it is possible to suppress the enlargement of the apparatus main body 110, and it is not necessary to provide a complicated mechanism for that purpose, and it is possible to suppress the complication of the configuration.

  In the present embodiment, in the black and white image forming mode, the intermediate transfer belt 9 is held between the roller member 72 provided on the separating member 70 and the primary transfer roller 5 in the color image forming portion and has sufficient restraining force. Is granted. Due to the restraining force of the roller member 72 and the primary transfer roller 5, it is possible to suppress the speed fluctuation of the intermediate transfer belt 9 that occurs when, for example, the transfer material S enters the secondary transfer portion T2 in the black and white image forming mode. That is, according to the present embodiment, the change in the restraining force (constraining condition) on the intermediate transfer belt 9 in the black and white image forming mode and the color image forming mode is made sufficiently small to prevent the intermediate transfer belt 9 from being disturbed. Can stabilize the speed. Therefore, for example, it is possible to suppress the load fluctuation that occurs when the transfer material P enters the secondary transfer portion T2. Further, since the running of the intermediate transfer belt 9 is stabilized, it is possible to suppress image deterioration such as a streak image due to speed fluctuation even in the monochrome image forming mode.

[Example 2]
Next, another embodiment of the present invention will be described. The basic configuration and operation of the image forming apparatus of this embodiment are the same as those of the first embodiment. Therefore, in the image forming apparatus of this embodiment, elements having the same or corresponding functions or configurations as those of the image forming apparatus of Embodiment 1 are denoted by the same reference numerals, and detailed description thereof is omitted.

  FIG. 9 is an external perspective view of the drum unit 7 in the present embodiment. In this embodiment, the drum unit 7 is provided coaxially with the photosensitive drum 1 at both ends in the longitudinal direction of the photosensitive drum 1, and is capable of rotating relatively with respect to the surface of the photosensitive drum 1. Have

  On the other hand, in this embodiment, the separating member 70 does not have the cover member 73 provided in Embodiment 1, and the roller member 72 slips from the intermediate transfer belt 9 when the separating member 70 is in the operating position. Contact the ring 17.

  As in the first embodiment, in the monochrome image forming mode, the separation member 70 is used to separate the intermediate transfer belt 9 from the photosensitive drum 1 in the primary transfer portion T1 for color image forming portions PY, PM, and PC. And the intermediate transfer belt 9. At this time, in this embodiment, the roller member 72 provided on the separation member 70 contacts the slip rings 17 provided on both ends of the photosensitive drum 1. In the present embodiment, when the separation member 70 is disposed at the operating position, the slip ring 17 rotates as the roller member 72 rolls on the intermediate transfer belt 9, so that the separation member 70 and the photosensitive drum 1 are rotated. Easy to insert between the intermediate transfer belt 9.

  Similarly to the first embodiment, in the black and white image forming mode, the roller member 72 rotates following the movement of the intermediate transfer belt 9 while the intermediate transfer belt 9 is rotating. Then, the slip ring 17 also rotates following the rotation of the roller member 72. Thereby, even if the rotation of the photosensitive drum 1 is stopped, the rotation of the intermediate transfer belt 9 is stabilized.

  As described above, according to the present embodiment, the same effects as those of the first embodiment can be obtained, and the load of the roller member 72 can be reduced when the photosensitive drum 1 is stopped without providing the cover member 73 in the first embodiment. Can be reduced.

[Others]
As mentioned above, although this invention was demonstrated according to the specific Example, this invention is not limited to the above-mentioned Example.

  In the above embodiment, the intermediate transfer type image forming apparatus in which the moving body is an intermediate transfer body has been described as an example. However, the present invention is also applicable to a direct transfer type image forming apparatus in which the moving body is a transfer material carrier. can do. FIG. 10 is a schematic cross-sectional configuration diagram of a direct transfer type image forming apparatus. In the figure, elements having the same or corresponding functions or configurations as those of the image forming apparatus of FIG. The image forming apparatus of FIG. 10 has a transfer material carrying belt 18 formed of an endless belt as a transfer material carrying body instead of the intermediate transfer belt 9 in the image forming apparatus of FIG. The transfer material carrying belt 18 is an example of a moving body that can move in contact with the photosensitive drum 1 and carries and conveys the transfer material S onto which the toner image is transferred from the photosensitive drum 1. The toner images formed on the respective photosensitive drums 1 are sequentially transferred onto the transfer material S carried on the transfer material carrying belt 18 at each transfer portion T. Also in such an image forming apparatus, in the monochrome image forming mode, the transfer material carrying belt 18 is separated from the photosensitive drum 1 in the color image forming portions PY, PM, and PC to stop the rotation of the photosensitive drum 1 and the like. Is desired. Therefore, also in such an image forming apparatus, the transfer material T carries the transfer material from the photosensitive drum 1 in the transfer portion T in the same manner as the intermediate transfer belt 9 is separated from the photosensitive drum 1 in the primary transfer portion T1 in the above-described embodiment. The belt 18 can be separated. Thereby, the same effect as the above-mentioned Example is acquired. Regarding the details of the configuration and operation of the separation mechanism 80, the description of the above-described embodiment is used by making appropriate replacements such as replacing the intermediate transfer belt 9 in the above-described embodiment with the transfer material carrying belt 18, and the like. Description is omitted.

  In the above-described embodiments, the case where the image forming apparatus has the color image forming mode and the monochrome image forming mode has been described as an example. However, according to the present invention, the moving body is separated from the image carrier in some or all of the image forming units for the case where the image forming apparatus has a single color image forming mode of another color, or for an adjustment operation or a maintenance operation. The present invention can also be applied when a separation mechanism is to be provided. In other words, the present invention can be applied if the image forming apparatus has at least one image forming unit that needs to move the moving body away from the image carrier. For example, there may be an image forming mode in which a toner image is formed in at least two image forming units, not all of the plurality of image forming units, and a toner image is not formed in one or more other image forming units. . Further, for example, in order to prevent the adjustment toner image formed on the image carrier in the adjustment operation from coming into contact with the moving body, a part or all of the plurality of image forming units in the adjustment operation. In this case, the moving body may be separated from the image carrier. When the moving body is separated from the image carrier in the plurality of image forming units, the separation timing may be substantially the same timing or different timing.

  In the above-described embodiment, the case where the separation member is provided with the rotation member has been described. Accordingly, as described in the above-described embodiment, the rotating member rotates while contacting the moving body or the image carrier when the separating member is disposed at the operating position or during image formation, and the separating member and the moving body are rotated. Alternatively, the load on the image carrier or the like is reduced. However, the present invention is not limited to this, and the separation member is configured to have a sufficiently low frictional resistance at the contact portion between the separation member and the moving body or the image carrier. The structure which rubs may be sufficient.

DESCRIPTION OF SYMBOLS 1 Photosensitive drum 5 Primary transfer roller 9 Intermediate transfer belt 30 Drum drive motor 40 1st drive transmission part 60 2nd drive transmission part 70 Separation member 71 Support part 72 Roller member 73 Cover member 74 Rack member 80 Separation mechanism

Claims (11)

A rotatable image carrier carrying a toner image;
It is movable in contact with the image carrier and carries and conveys a toner image transferred from the image carrier or carries and transfers a transfer material onto which a toner image is transferred from the image carrier. A moving object,
A first position that is retracted from between the image carrier and the movable body and allows the movable body to contact the image carrier, and is disposed between the image carrier and the movable body. A separation member that is movable between a second position that urges the movable body in a direction away from the image carrier and separates the movable body from the image carrier;
Rotatable drive means for rotating the image carrier;
A first drive transmission section for transmitting a driving force from the driving means to the image carrier;
A second drive transmission portion for transmitting a driving force from the drive means to the separation member;
Have
The first drive transmission unit transmits the driving force from the driving means rotating in the first direction to the image carrier to rotate the image carrier, and the first drive transmission unit rotates in the direction opposite to the first direction. Release the drive transmission from the drive means rotating in the direction of 2 to the image carrier,
The second drive transmission unit transmits a driving force from the driving means rotating in the second direction to the separation member to move the separation member from the first position to the second position. An image forming apparatus, wherein a driving force from the driving means rotating in the first direction is transmitted to the separation member to move the separation member from the second position to the first position. .   2. The rotation member according to claim 1, wherein the separation member includes a rotation member that is rotatable in contact with the moving body and following the movement of the moving body when the separation member is in the second position. The image forming apparatus described.   3. The spacing member includes a cover member that is disposed between the rotating member and the image carrier and is in contact with the surface of the image carrier when in the second position. The image forming apparatus described in 1.   The image forming apparatus according to claim 3, wherein the cover member is in contact with a surface of the image carrier in a non-image forming region at an end portion in a rotation axis direction of the image carrier. A rotation part provided at an end of the image carrier in the rotation axis direction and rotatable relative to the surface of the image carrier;
3. The image according to claim 2, wherein the rotation unit is rotatable by contacting the rotation member and following the rotation of the rotation member when the separation member is in the second position. Forming equipment. A transfer member that performs the transfer when a voltage is applied is disposed opposite to the image carrier via the moving body,
The transfer member holds the moving body between the transfer member and the image carrier when the separation member is in the first position, and the transfer member and the separation member when the separation member is in the second position. The image forming apparatus according to claim 1, wherein the moving body is sandwiched between the two. The image carrier and the separation member are integrally provided in a unit that can be attached to and detached from the apparatus main body of the image forming apparatus.
The separation member also serves as a protection member that is disposed at a position corresponding to the second position when the unit is detached from the apparatus main body and protects the image carrier. The image forming apparatus according to any one of 1 to 6.   The image forming apparatus according to claim 1, further comprising a cleaning member that contacts the surface of the image carrier and removes deposits on the surface of the image carrier.   A developer container that contains a developer containing toner; and a stirring member that rotates in synchronization with the rotation of the image carrier and stirs the developer contained in the developer container. The image forming apparatus according to claim 1, further comprising a developing device that forms an image. When the image carrier is a first image carrier, a second image carrier different from the first image carrier;
Second driving means for rotating the second image carrier;
A toner image can be transferred from the first and second image carriers to the moving member that moves in contact with the first and second image carriers or to a transfer material supported on the movable member. The first image forming mode and the moving body that moves in contact with only the second image carrier among the first and second image carriers, or the transfer material carried on the movable body. A second image forming mode capable of transferring a toner image from the second image carrier, and an execution unit that selectively executes the second image forming mode;
Have
When executing the second image forming mode, the execution unit rotates the driving unit in the second direction to move the moving unit away from the first image carrier, and the driving unit The image forming apparatus according to claim 1, wherein after the stop, rotation of the second image carrier by the second driving unit is started.   The image forming apparatus according to claim 10, further comprising a plurality of the first image carriers.

Images