JP2008033372A - Image forming apparatus - Google Patents

Abstract

An image forming apparatus capable of detachably attaching a transfer carrier device (contact member) using a space formed by opening an exterior with a simple configuration.
The image forming apparatus includes photosensitive drums 3a to 3d, a removable transfer belt unit 8, and a rail member 201 that supports the transfer belt unit 8. The rail member 201 regulates the position of the rail groove 202 that guides the transfer belt unit 8, the recess 202a / positioning hole 202b for positioning when the transfer belt unit 8 contacts, and the position of the transfer belt unit 8 when separated. 202c. The transfer belt unit 8 is released from the support of the image forming apparatus main body by the rail member 201 by the operation of opening the side cover 35 and is in a free state.
[Selection] Figure 1

Description

  The present invention relates to an image forming apparatus including a transfer carrier device in which a transfer carrier is stretched.

  A transfer carrier device provided in an image forming apparatus and including a sheet (recording medium) to which an image formed on the image carrier is conveyed and a transfer carrier that transfers the image to itself is generally provided with a drive roller. At least two roller members are provided, and an endless transfer carrier is stretched between the roller members so as to be rotatable.

  In such a transfer carrier device, the transfer carrier is rotated and moved by a driving roller, whereby the formed image is transferred and the sheet is conveyed. Along with this operation, the transfer carrier is worn out, fatigued, adhered to dirt, etc., and the performance of the transfer carrier gradually decreases.

  For this reason, the transfer carrier is normally replaced periodically after a predetermined period of use. At this time, the entire transfer carrier device may be replaced, but generally only the transfer carrier is often replaced. In any case, it is necessary to take out the transfer carrier device from the inside of the image forming apparatus and return it again after replacement.

  In addition, in an image forming apparatus that carries a sheet on a transfer carrier and transfers an image formed on the image carrier onto the sheet, the sheet is sandwiched between the image carrier and the transfer carrier so that the transfer is good. To be done.

  Therefore, when a sheet is jammed due to some kind of trouble, the image transfer onto the sheet is performed well when the sheet is stopped while the sheet is staying on the transfer carrier. In many cases, the sheet staying on the transfer carrier must be removed.

  However, when the sheet is sandwiched between the image carrier and the transfer carrier, it is difficult to remove the sheet, and one of the image carrier and the transfer carrier device must be separated from the other.

  This separation distance is restricted by the size of the image carrier, the transfer carrier, the image forming apparatus, and the like, and cannot be so large. Accordingly, the separation distance is very small, and there is almost no gap for inserting a finger or hand to grip the sheet staying on the transfer carrier. Therefore, the image forming apparatus is usually located below the image forming apparatus. Pull out to remove the staying sheet.

  For example, there is an image forming apparatus configured to pull out the entire lifting / lowering mechanism from the image forming apparatus after the transfer carrier apparatus is lowered by operating the handle and separated from the image carrier (see, for example, Patent Document 1).

  In addition, for example, there is an image forming apparatus that supports a transfer carrier device on a drawer so as to be movable up and down. In this image forming apparatus, after the transfer carrier device is lowered and separated from the image carrier, the drawer is pulled out from the image forming device, and when a jam occurs, the staying sheet is taken out, cleaned, or the transfer carrier device Maintenance such as replacement is performed (for example, see Patent Document 2).

Further, there is an image forming apparatus in which the transfer belt is separated from the photosensitive drum on the opened side in conjunction with opening and closing of the exterior from a plurality of directions. Thereby, jam processing can be performed from an appropriate direction (see, for example, Patent Document 3).
JP-A-2-163238 (published on June 22, 1990) Japanese Patent No. 2861721 (Registered on December 11, 1998, JP-A-6-316347; published on November 15, 1994) JP 2002-214874 A (released July 31, 2002)

  However, the image forming apparatus disclosed in Patent Document 1 has a large space below the image forming apparatus in order to operate the lifting mechanism such as a release lever to greatly lower the transfer carrier apparatus in the case of jam handling or maintenance. Requires a lift mechanism.

  Further, in the configuration described in Patent Document 2, since the drawer is pulled out from the image forming apparatus, the size of the part to be pulled out and moved becomes very large. In such a structure, a large lever or the like for separating the transfer carrier device from the image carrier must be operated after the cabinet (exterior) is opened. However, there is a problem that not only the size of the image forming apparatus is increased, but also the weight is increased.

  Further, in the case where the image forming apparatus is a tandem type image forming apparatus in which a plurality of image carriers are arranged side by side, the movement direction of the transfer carrier of the transfer carrier device (perpendicular to the axis of the roller member that supports the transfer carrier) Direction) is larger than the width in the pull-out direction, so that when the transfer carrier device is pulled out in a direction perpendicular to the rotational movement direction of the transfer carrier member, the drawer on which the transfer carrier device is supported is pulled out. This causes a problem that the opening width of the image forming apparatus becomes very large, and the strength on the drawer side of the frame of the image forming apparatus tends to decrease.

  The decrease in the strength of the frame (frame body) of the image forming apparatus becomes more prominent as the area of the opening that is pulled out for replacement or maintenance of a plurality of units involved in image formation becomes larger. If the direction of pulling out is the same as the direction of pulling out the transfer carrier device for replacement or maintenance, the area of the opening must be further increased, and the strength is extremely reduced.

  For this reason, it is necessary to use a reinforcing member or to increase the thickness of the material constituting the frame (frame body), which increases the size of the device and increases the weight.

  Further, in the configuration described in Patent Document 3, the exterior can be opened from a plurality of directions, and the transfer belt is separated from the photosensitive drum on the side where the exterior is opened, so that the configuration is complicated. At the same time, the transfer carrier device including the transfer belt is not completely free. Therefore, for example, when replacing the transfer carrier device, it is necessary to make the transfer carrier device completely free.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a transfer carrier device (contact member) by utilizing a space formed by opening an exterior with a simple configuration. An object of the present invention is to provide an image forming apparatus that can be attached and detached.

  In order to solve the above problems, an image display device according to the present invention has an image carrier on which an image is formed based on image data, and is detachable from the image carrier and is in contact with the image carrier. In the image forming apparatus comprising the transfer carrier device having the transfer carrier for transferring the image by the above, the transfer carrier device is configured such that the image carrier is operated by opening a part of the exterior of the image forming device. It is characterized by being separated from the body.

  According to the above configuration, the transfer carrier device is separated from the image carrier by the operation of opening the exterior. Therefore, the transfer carrier provided in the transfer carrier device is completely separated from the image carrier, and the recording medium (sheet) staying on the transfer carrier device can be easily taken out due to a jam or the like.

  At this time, the transfer carrier device may be in a free state, and if it is in a free state, only the transfer carrier device can be easily taken out of the image forming apparatus as it is.

  Therefore, the release lever for separating the transfer carrier device from the normally provided image carrier is not operated after the exterior is released, and the release carrier is not pulled out together with the separation mechanism after the release lever is operated. That's it. Accordingly, the number of steps for taking out the transfer carrier device for jam handling work and maintenance can be reduced, and speedy work can be performed.

  Further, since the transfer carrier device is not pulled out from the image forming apparatus together with the release lever and the separation mechanism, the image forming apparatus can be reduced in size and weight, and the manufacturing cost and the maintenance cost can be reduced. be able to.

  In order to solve the above-described problems, an image forming apparatus according to the present invention includes an image carrier on which an image is formed based on image data, and an image carrier that is separable from and in contact with the image carrier. An image forming apparatus including a transfer carrier device having a transfer carrier for transferring the image, wherein the transfer carrier device is configured to open the image forming device by an operation of opening a part of the exterior of the image forming device. The support for the main body is released.

  According to the above configuration, since the positioning support of the transfer carrier device is released by the operation of opening the exterior, the transfer carrier device can be in a free state with respect to the image forming apparatus.

  Therefore, the transfer carrier provided in the transfer carrier device is completely separated from the image carrier, and a sheet staying on the transfer carrier device can be easily taken out due to a jam or the like. Further, only the transfer carrier device can be taken out from the image forming apparatus as it is.

  As a result, the release lever for separating the transfer carrier device from the normally provided image carrier is not operated after the exterior is released, and the transfer carrier device is not pulled out together with the separation mechanism after the release lever is operated. It will end. Accordingly, the number of steps for taking out the transfer carrier device for jam handling work and maintenance can be reduced, and speedy work can be performed.

  Further, since the transfer carrier device is not pulled out from the image forming apparatus together with the release lever and the separation mechanism, the image forming apparatus can be reduced in size and weight, and the manufacturing cost and the maintenance cost can be reduced. be able to.

  In the image display device described above, a part of the exterior is an exterior parallel to the axis of the roller member that rotatably supports the transfer carrier of the transfer carrier apparatus among the exteriors of the image forming apparatus. It is preferable to open in the direction orthogonal to the direction.

  According to the above configuration, a part of the exterior is an exterior parallel to any one of the four surfaces excluding the frame (front frame / rear frame) in the image forming apparatus. Therefore, it is not necessary to provide an opening for attaching and detaching the transfer carrier device to the frame, so that the strength of the frame is not reduced. For this reason, it is not necessary to increase the thickness of the frame and increase the strength of the frame, so that the weight of the image forming apparatus can be reduced.

  In general, when the exterior is opened in a direction parallel to the axis of the roller member, particularly in the case of a tandem type image display device, the opening becomes large and the strength of the frame is reduced.

  However, the transfer carrier device is moved to the image forming apparatus main body as compared with the case where the outer surface of the transfer carrier device is moved in a direction perpendicular to the axis of the roller member to move it parallel to the axis of the roller member. On the other hand, the mechanism for positioning and supporting can be formed compactly.

  Also, opening the exterior in a direction orthogonal to the axis of the roller member that supports the transfer carrier device opens the exterior toward the upstream side or the downstream side in the sheet conveyance direction.

  Therefore, when a jam or the like occurs, it is possible to easily pull the jammed sheet upstream or downstream in the conveyance direction by grasping the leading edge or the trailing edge of the sheet. As a result, it is possible to prevent the sheet from being torn when being pulled out and leaving a torn piece of the sheet in a narrow area where a hand cannot be inserted.

  In the image forming apparatus, it is preferable that the transfer carrier device is detachable from the image forming apparatus main body, and the attachment / detachment is performed when a part of the exterior is opened.

  Usually, in the transfer carrier device, at least two frames (front frame and rear frame) are formed orthogonal to the axis of the roller member that supports the transfer carrier, and the roller member is supported by these frames.

  According to the above configuration, for example, by forming the support member for positioning and supporting the transfer carrier device on the frame so as to be close to the frame, the transfer carrier device is moved by moving the support member along the guide member. Can be made. Accordingly, the transfer carrier device can be easily attached to and detached from the image forming apparatus.

  As a result, the transfer carrier device is attached to and detached from the image forming apparatus in a direction perpendicular to the axis of the roller member that supports the transfer carrier, that is, a direction parallel to the frame of the image forming apparatus. Therefore, the transfer carrier device can be easily attached and detached along the frame.

  Further, it is not necessary to provide an opening for attaching / detaching the transfer carrier device to the frame, so that the strength of the frame is not lowered. For this reason, since it is not necessary to increase the thickness of the frame and increase the strength of the frame, it is possible to reduce the weight of the image forming apparatus.

  In the image forming apparatus, the frame member of the main body of the image forming apparatus includes a positioning member for positioning the transfer carrier device with respect to the main body of the image forming apparatus, and the positioning member is a transfer carrier on the positioning member. It is preferable to have a position restricting means for restricting the displacement of the apparatus.

  Usually, if the transfer carrier device is moved carelessly, problems such as damage to the transfer carrier device and inability to position the transfer carrier device by the positioning member occur when an operation for closing the exterior is performed.

  However, according to the above configuration, when the transfer carrier apparatus is released from the support for positioning by the position restricting means and becomes free, the transfer carrier apparatus does not inadvertently shift its position. Can be.

  Further, for example, when the positioning member has a concave portion or the like as the position regulating means, it can be confirmed that the transfer carrier device can be reliably inserted into the image forming apparatus by the feeling obtained when the transfer carrier device is inserted. it can.

  The image forming apparatus includes a rail member that guides the transfer carrier device when the frame member of the image forming apparatus main body is attached or detached, and the rail member positions the transfer carrier device with respect to the image forming apparatus main body. It is preferable to include a positioning means for performing the positioning, and a position regulating means for regulating the displacement of the transfer carrier device in the rail member when a part of the exterior of the image forming apparatus is opened.

  According to the above configuration, when the support for positioning of the transfer carrier device is released by the position restricting means and becomes free, the transfer carrier device does not inadvertently shift its position. can do.

  Further, for example, when the positioning means is a recess, it can be confirmed that the transfer carrier device can be reliably inserted into the image forming apparatus by the feeling obtained when the transfer carrier device is inserted.

  In the image forming apparatus, it is preferable that the position regulating unit is a recess that is disposed so as to face the positioning unit and regulates the positional deviation of the shaft of the roller member that rotatably supports the transfer carrier.

  According to said structure, even when a transfer carrier apparatus becomes a free state, it can control so that a transfer carrier apparatus may not move from a predetermined range in a recessed part. Further, since the concave portion is opposed to the positioning means, since the positional deviation of the transfer carrier device is restricted even when the transfer carrier device is positioned, the positioning can be easily performed.

  Further, when the transfer carrier device is guided (inserted) along the rail member, the user can recognize that the transfer carrier device is in the concave portion, so that the user can securely connect the transfer carrier device to the image forming apparatus. It can be confirmed that it has been inserted.

  When the transfer carrier is in contact with the image carrier, the image forming apparatus is engaged with the image carrier unit including the image carrier, while the transfer carrier is not in contact with the image carrier. It is preferable to include a blocking member that is disengaged from the image carrier unit and moves in conjunction with the opening / closing operation of the exterior.

  According to the above configuration, the blocking member can protect the image carrier unit from being pulled out of the image forming apparatus when the transfer carrier is in contact with the image carrier. On the other hand, it is possible to prevent the surface of the image carrier or the surface of the transfer carrier from being damaged by accidentally pulling out the image carrier unit while the transfer carrier is still in contact with the image carrier.

  An image forming apparatus according to the present invention includes an image carrier on which an image is formed based on image data, and a transfer carrier that is detachable from the image carrier and transfers the image by contacting the image carrier. In the image forming apparatus including the transfer carrier device, the transfer carrier device is attached to and detached from the image forming apparatus main body in a direction perpendicular to the axis of the roller member that rotatably supports the transfer carrier. It is characterized by being performed by moving the transfer carrier device.

  Usually, in the transfer carrier device, at least two frames (front frame and rear frame) are formed orthogonal to the axis of the roller member that supports the transfer carrier, and the roller member is supported by these frames.

  According to the above configuration, for example, by forming the support member for positioning and supporting the transfer carrier device on the frame so as to be close to the frame, the transfer carrier device is moved by moving the support member along the guide member. Can be made. Accordingly, the transfer carrier device can be easily attached to and detached from the image forming apparatus.

  As a result, the transfer carrier device is attached to and detached from the image forming apparatus in a direction perpendicular to the axis of the roller member that supports the transfer carrier, that is, a direction parallel to the frame of the image forming apparatus. Therefore, the transfer carrier device can be easily attached and detached along the frame.

  Further, it is not necessary to provide an opening for attaching / detaching the transfer carrier device to the frame, so that the strength of the frame is not lowered. For this reason, since it is not necessary to increase the thickness of the frame and increase the strength of the frame, it is possible to reduce the weight of the image forming apparatus.

  In the image forming apparatus, it is preferable that a plurality of image carriers are arranged in a direction perpendicular to the axis of a roller member that rotatably supports the transfer carrier.

  In general, in a so-called tandem type image forming apparatus in which a plurality of image carriers are arranged in a direction orthogonal to the axis of a roller member that supports a transfer carrier, the size of the transfer carrier device is large. In the body device, the size in the direction in which the transfer carrier moves is larger.

  However, according to the above configuration, the transfer carrier device is moved in the direction orthogonal to the axis of the roller member, and the transfer carrier device is attached to and detached from the image forming apparatus main body, thereby transferring even a small opening space. The carrier device can be attached and detached.

  Further, the reduction in the strength of the frame of the image forming apparatus can be reduced as compared with the structure in which the frame is moved in a direction parallel to the axis of the roller member that supports the transfer carrier. Further, even in a structure in which the frame is provided in parallel to the direction orthogonal to the axis of the roller member that supports the transfer carrier (the moving direction of the transfer carrier and the recording member), the transfer carrier device is detachable from the frame. It is not necessary to provide an opening. Therefore, it is not necessary to increase the thickness of the frame and increase the strength of the frame, so that the weight of the image forming apparatus can be reduced.

  In order to solve the above-described problems, the image forming apparatus of the present invention can be separated from and contacted to an image carrier on which an image is formed based on image data, and a voltage is applied by a transfer member. And a transfer carrier device having a transfer carrier for transferring the image, wherein a plurality of the image carriers are arranged in a direction perpendicular to an axis of a roller member that rotatably supports the transfer carrier. An image forming mode in which all the image carriers are used in contact with the transfer carrier, and image formation in which any one of the plurality of image carriers is used in contact with the transfer carrier In an image forming apparatus having a mode, when an image forming mode using the specific image carrier is selected, transfer corresponding to an image carrier not used and at least excluding a transfer member located at an end portion Material Is characterized by being configured such that the non-contact state with the transfer carrier.

  Usually, in an image forming mode (monochrome mode) using a specific image carrier, the contact force between the transfer member corresponding to the image carrier not used for image formation and the transfer carrier is reduced, particularly at the end. The contact force between the transfer member excluding the positioned transfer member and the transfer carrier is extremely reduced. For this reason, the transfer member corresponding to the unused image carrier and excluding the transfer member located at least at the end cannot be rotated by the frictional force with the transfer carrier. For this reason, uneven wear of the transfer member that cannot be rotated occurs, and as a result, troubles such as a reduction in the life of the transfer member and uneven transfer occur.

  However, according to the above configuration, by making such a transfer member non-contact with the transfer carrier, these problems can be prevented and good image formation can be maintained for a long time. .

  As described above, in the image display device of the present invention, the transfer carrier device is configured to be separated from the image carrier by the operation of opening a part of the exterior of the image forming apparatus.

  Accordingly, the transfer carrier device is separated from the image carrier by the operation of opening the exterior. Therefore, the transfer carrier provided in the transfer carrier device is completely separated from the image carrier, and the recording medium (sheet) staying on the transfer carrier device can be easily taken out due to a jam or the like.

  At this time, the transfer carrier device may be in a free state, and if it is in a free state, only the transfer carrier device can be easily taken out of the image forming apparatus as it is.

  Therefore, the release lever for separating the transfer carrier device from the normally provided image carrier is not operated after the exterior is released, and the release carrier is not pulled out together with the separation mechanism after the release lever is operated. That's it. Accordingly, the number of steps for taking out the transfer carrier device for jam handling work and maintenance can be reduced, and speedy work can be performed.

  Further, since the transfer carrier device is not pulled out from the image forming apparatus together with the release lever and the separation mechanism, the image forming apparatus can be reduced in size and weight, and the manufacturing cost and the maintenance cost can be reduced. There is an effect that can be.

  As described above, the image forming apparatus of the present invention is configured such that the transfer carrier device is released from the support to the image forming apparatus main body by the operation of opening a part of the exterior of the image forming apparatus.

  Accordingly, the positioning support of the transfer carrier device is released by the operation of opening the exterior, so that the transfer carrier device can be in a free state with respect to the image forming apparatus.

  Therefore, the transfer carrier provided in the transfer carrier device is completely separated from the image carrier, and a sheet staying on the transfer carrier device can be easily taken out due to a jam or the like. As a result, the number of procedures for taking out the transfer carrier device for jam handling work and maintenance can be reduced, and speedy work can be performed.

  Further, since the transfer carrier is not pulled out from the image forming apparatus together with the release lever and the separation mechanism, the image forming apparatus can be reduced in size and weight, and the manufacturing cost and the maintenance cost can be reduced. There is an effect that can be.

  In the image display device of the present invention, a part of the exterior is an exterior parallel to the axis of the roller member that rotatably supports the transfer carrier of the transfer carrier device among the exteriors of the image forming apparatus. It is the structure open | released in the direction orthogonal to an axis | shaft.

  As a result, a part of the exterior is an exterior parallel to any of the four surfaces except the frame in the image forming apparatus, and therefore there is no need to provide an opening for attaching or detaching the transfer carrier device to the frame. Does not cause a decrease in frame strength. For this reason, it is not necessary to increase the thickness of the frame and increase the strength of the frame, so that the weight of the image forming apparatus can be reduced.

  Further, the mechanism for positioning and supporting the transfer carrier device with respect to the main body of the image forming apparatus can be formed more compactly than when moving in parallel with the axis of the roller member.

  Furthermore, opening the exterior in a direction orthogonal to the axis of the roller member that supports the transfer carrier device opens the exterior toward the upstream side or the downstream side in the sheet conveyance direction.

  Therefore, when a jam or the like occurs, it is possible to easily pull the jammed sheet upstream or downstream in the conveyance direction by grasping the leading edge or the trailing edge of the sheet. As a result, there is an effect that it is possible to prevent the sheet from being torn when being pulled out and leaving a torn piece of the sheet in a narrow place where a hand cannot be inserted.

  The image forming apparatus of the present invention has a configuration in which the transfer carrier device is detachable from the image forming apparatus main body, and is attached and detached when a part of the exterior is opened.

  Accordingly, the transfer carrier device can be easily attached to and detached from the image forming apparatus.

  Accordingly, when the transfer carrier device is attached to or detached from the image forming apparatus, the transfer carrier device is placed in a direction perpendicular to the axis of the roller member that supports the transfer carrier, that is, in a direction parallel to the frame of the image forming device. The transfer carrier device can be easily attached and detached along the frame because the opening is formed by moving and moving the exterior in the same direction in advance.

  Further, it is not necessary to provide an opening for attaching / detaching the transfer carrier device to the frame, so that the strength of the frame is not lowered. For this reason, since it is not necessary to increase the thickness of the frame and increase the strength of the frame, there is an effect that the weight of the image forming apparatus can be reduced.

  In the image forming apparatus of the present invention, the frame member of the image forming apparatus main body includes a positioning member for positioning the transfer carrier device with respect to the image forming apparatus main body, and the positioning member is a transfer carrier on the positioning member. It is the structure which has the position control means for controlling the position shift of a body apparatus.

  As a result, the transfer carrier device can be prevented from inadvertently being displaced when the support for positioning is released by the position restricting means and becomes free. There is an effect.

  In the image forming apparatus of the present invention, the frame member of the image forming apparatus main body includes a rail member that guides the transfer carrier apparatus when the image forming apparatus main body is attached or detached. The image forming apparatus includes a positioning unit for positioning, and a position regulating unit for regulating a displacement of the transfer carrier device in the rail member when a part of the exterior of the image forming apparatus is opened.

  As a result, the transfer carrier device can be prevented from inadvertently being displaced when the support for positioning is released by the position restricting means and becomes free. There is an effect.

  The image forming apparatus of the present invention has a configuration in which the position restricting unit is a recess that is disposed so as to face the positioning unit and restricts the positional deviation of the shaft of the roller member that rotatably supports the transfer carrier.

  As a result, even when the transfer carrier device is in a free state, the transfer carrier device can be regulated so as not to move from a predetermined range in the recess. Further, since the concave portion is opposed to the positioning means, since the positional deviation of the transfer carrier device is restricted even when the transfer carrier device is positioned, the positioning can be easily performed.

  Further, when the transfer carrier device is guided (inserted) along the rail member, the user can recognize that the transfer carrier device is in the concave portion, so that the user can securely connect the transfer carrier device to the image forming apparatus. The effect that it can confirm that it was able to insert is produced.

  In the image forming apparatus of the present invention, when the transfer carrier is in contact with the image carrier, the image carrier is engaged with the image carrier unit including the image carrier, while the transfer carrier is not in contact with the image carrier. Is configured to include a blocking member that is disengaged from the image carrier unit and moves in conjunction with the opening / closing operation of the exterior.

  Thus, when the transfer carrier is in contact with the image carrier, the image carrier unit can be protected from being pulled out of the image forming apparatus. On the other hand, it is possible to prevent the surface of the image carrier or the surface of the transfer carrier from being scratched by accidentally pulling out the image carrier unit while the transfer carrier is still in contact with the image carrier. Play.

  In the image forming apparatus of the present invention, as described above, the transfer carrier apparatus is attached to and detached from the image forming apparatus main body in the direction perpendicular to the axis of the roller member that rotatably supports the transfer carrier. This is a configuration performed by movement.

  Accordingly, the transfer carrier device can be easily attached to and detached from the image forming apparatus.

  Accordingly, when the transfer carrier device is attached to or detached from the image forming apparatus, the transfer carrier device is placed in a direction perpendicular to the axis of the roller member that supports the transfer carrier, that is, in a direction parallel to the frame of the image forming device. The transfer carrier device can be easily attached and detached along the frame because the opening is formed by moving and moving the exterior in the same direction in advance.

  Further, it is not necessary to provide an opening for attaching / detaching the transfer carrier device to the frame, so that the strength of the frame is not lowered. For this reason, since it is not necessary to increase the thickness of the frame and increase the strength of the frame, there is an effect that the weight of the image forming apparatus can be reduced.

  The image forming apparatus of the present invention has a configuration in which a plurality of image carriers are arranged in a direction perpendicular to the axis of a roller member that rotatably supports a transfer carrier.

  Thereby, the transfer carrier device can be attached and detached even in a small opening space. Further, the reduction in the strength of the frame of the image forming apparatus can be reduced as compared with the structure in which the frame is moved in a direction parallel to the axis of the roller member that supports the transfer carrier. Further, even in a structure in which the frame is provided in parallel to the direction orthogonal to the axis of the roller member that supports the transfer carrier (the moving direction of the transfer carrier and the recording member), the transfer carrier device is detachable from the frame. It is not necessary to provide an opening.

  Therefore, it is not necessary to increase the thickness of the frame and increase the strength of the frame, so that the image forming apparatus can be reduced in weight.

  As described above, when the image forming mode using a specific image carrier is selected, the image forming apparatus of the present invention corresponds to an image carrier that is not used, and is at least positioned at the end. The transfer member except for is configured to be in a non-contact state with the transfer carrier.

  As a result, it is possible to prevent the occurrence of life reduction, transfer unevenness, etc., and to maintain good image formation for a long time.

  An embodiment of the present invention will be described with reference to FIGS. 1 to 24 as follows.

  FIG. 1 shows contact / separation of a transfer belt unit 8 (transfer carrier device, contact member) of the image forming apparatus according to the present embodiment with respect to the photosensitive drums 3a to 3d (image carrier, support member). The structure of the principal part of a mechanism is shown. As shown in the figure, this separation / contact mechanism moves the transfer belt unit 8 to either an image forming position or a free position where the transfer belt unit 8 is separated from any of the photosensitive drums 3a to 3d and is in a free state. Hold. The separation / contact mechanism includes a rail member 201 (a support member and a positioning member) and a slide portion 18 (a biasing member) that interlocks with a side cover 35 (a part of the exterior) of the image forming apparatus.

  Here, as shown in FIG. 15, the exterior of the image forming apparatus includes a front frame 205 on the operation side, a rear frame 206 on the rear side (rear side), and a side cover 35 that can be opened and closed. The front and rear frames 205 and 206 (frame members, frames) are main frame members of the image forming apparatus. In the present embodiment, the side cover 35 constitutes a part of the side surface of the image forming apparatus. When the side cover 35 is in a closed state, the side cover 35 is used together with the side upper cover 28 (see FIGS. 1 and 2). A side surface of the exterior of the image forming apparatus is configured.

  The front frame 205 and the rear frame 206 are roller members (for example, a drive roller 71 and a tension roller 73 described later) for supporting a transfer belt 7 (transfer carrier, contact member) described later in the transfer belt unit 8. They are provided on the side surfaces orthogonal to the axis and parallel to the sheet conveying direction. With reference to the front and rear frames 205 and 206, each functional unit that executes an image forming process or the like is positioned and arranged.

  Further, below the transfer belt unit 8, as shown in FIG. 23, a slide plate including a fixed portion 17 and a slide portion 18 is disposed. The slide plate is interlocked with the side cover 35 and is pulled out together when the side cover 35 is pulled out. Here, the slide plate is made of Acculide (registered trademark), and two slide plates are arranged on the front frame 205 side and the rear frame 206 side.

  In the image forming apparatus, the transfer belt unit 8 is supported by rail members 201 and 201 that are respectively fixed inside the front frame 205 and the rear frame 206 (see FIG. 15).

  Further, as shown in FIG. 3, the transfer belt unit 8 includes support shafts 78 a and 78 b and a support member 50.

  As shown in FIG. 2, the rail member 201 (support member, positioning member) includes a unit lift arm 211 and a stop member lift arm 233, and a rail 203 on the surface 203 on the side where the transfer belt unit 8 is disposed. A groove 202 is provided. The rail groove 202 is for guiding the support shafts 78a and 78b of the transfer belt unit 8 in order to attach and detach the transfer belt unit 8 to and from the image forming apparatus.

  In addition, the rail groove 202 has concave portions 202a and 202c that face the vertical direction of the image forming apparatus, and a positioning hole 202b.

  The positioning hole (positioning means) 202b positions the support shaft 78b and rotatably supports the transfer belt unit 8. The concave portion (positioning means) 202 a performs positioning on the rotational movement side of the transfer belt unit 8. That is, the support shaft 78a is disposed at the image forming position by being pressed against the recess 202a.

  Further, a concave portion (position restricting means) 202c and a convex portion (position restricting means) 203a are arranged at a position facing the concave portion 202a. The concave portion 202c and the convex portion 203a prevent the displacement of the support shaft 78a when the transfer belt unit 8 is in a free state. Here, the free state means a state in which the support of the transfer belt unit 8 is released and the support shafts 78 a and 78 b of the transfer belt unit 8 are placed in contact with the lower surface of the rail groove 202.

  The convex portion 203a is arranged on the insertion port side (side cover 35 side) of the transfer belt unit 8 to the image forming apparatus from the concave portion 202a. The concave portions 202a and the convex portions 203a are provided to prevent the transfer belt unit 8 from inadvertently moving to the insertion port side and being displaced when the transfer belt unit 8 is in a free state. At the same time, it is provided so that it can be recognized that the transfer belt 7 has been inserted with a sense that can be felt when the transfer belt unit 8 is inserted.

  Note that both the concave portion 202a and the convex portion 203a may be provided, but the present invention is not limited to this, and only one of the concave portion 202a and the convex portion 203a can perform the above function.

  The unit lift arm 211 and the stop member lift arm 233 are rotatably supported by the rail member 201.

  As shown in FIG. 5, the unit lift arm 211 includes a lift block 212, a compression coil spring (elastic member) 213, and a lift roller 214.

  The lift block 212 is urged by a compression coil spring 213 in the direction of the arrow in the figure (the direction in which the photoconductive drums 3a to 3d are arranged) and is slidably supported.

  The lift roller 214 is rotatably attached to the unit lift arm.

  On the other hand, a slide portion 18 is disposed below the unit lift arm 211. As shown in FIG. 3, the slide part 18 includes slide cams 18a and 18b.

  As shown in FIG. 3, the lift roller 214 engages with the upper surface of the slide cam 18b. As shown in FIG. 2, the slide cam 18a engages with the stop member lift arm 233 at the flat portion 183 on the upper surface thereof, and engages with the separation control unit 38 at the slope portion 181 at the lower portion thereof. .

  The lift roller 214, the stop member lift arm 233, and the separation control unit 38 are configured to rotate in response to the opening / closing of the side cover 35.

  It should be noted that a slope portion 182 may be provided on the upper portion of the slide cam 18a so as to be in the same position as the lower slope portion 181 when attached to the opposing slide portion 18. Thus, the same component can be used by forming symmetrically. Therefore, the mold used at the time of manufacture can be made common, a mass production effect can be obtained, and the part cost can be reduced.

  Hereinafter, the insertion of the transfer belt unit 8 into the image forming apparatus will be described.

  As shown in FIG. 2, after the side cover 35 is opened (drawn), the transfer belt unit 8 is inserted from the wide open portion as indicated by an arrow in the figure. At this time, the transfer belt unit 8 is inclined and the support shaft 78 b is first fitted into the rail groove 202 of the rail member 201. Then, the transfer belt unit 8 is inserted into the image forming apparatus while sliding the support shaft 78b in the rail groove 202.

  At this time, the fixing device 12 pulled out together with the side cover 35 may be removed. As a result, it is possible to widen a portion that is opened when the transfer belt unit 8 is inserted (an insertion port into the image forming apparatus).

  Further, as the transfer belt unit 8 is inserted, the transfer belt unit 8 is brought into a horizontal state.

  When the support shaft 78a gets over the convex portion 203a and is positioned in the concave portion 202a, the transfer belt unit 8 is completely inserted into the image forming apparatus.

  Note that the user who has inserted the transfer belt unit 8 may recognize that the transfer belt unit 8 has been completely inserted by the feeling obtained when the support shaft 78a falls from the convex portion 203a to the concave portion 202a. it can.

  At this time, the transfer belt unit 8 is in a free state (a state in which the support is released), and the distance between the photosensitive drum 3 and the transfer belt 7 is sufficiently maintained.

  Next, the inserted transfer belt unit 8 is positioned by the rail member 201 (supports the transfer belt unit 8). This positioning is performed by closing the side cover 35.

  That is, after the transfer belt unit 8 is inserted, the side cover 35 is closed, whereby the slide portion 18 is guided to the fixed portion 17 and slides in the image forming apparatus.

  At this time, when the slide cam 18b is engaged (biased) with the unit lift arm 211, the unit lift arm 211 rotates upward. Thereby, the lift block 212 pushes up the support shaft 78b, and the support shaft 78b is guided to the positioning hole 202b. The support shaft 78b is supported by the positioning hole 202b by the pressing force of the compression coil spring 213. Thus, the support shaft 78b is positioned in the positioning hole 202b by closing the side cover 35.

  Note that the support shaft 78 b serves as a rotation fulcrum of the transfer belt unit 8 in this positioned and supported state. Therefore, the lift block 212 is preferably formed of self-lubricating material having good slipperiness, such as PON, so as not to hinder the rotation of the support shaft 78b.

  On the other hand, when the side cover 35 is closed, the support shaft 78a is also pushed up by the separation control unit 38 substantially simultaneously with the support shaft 78b, and is supported (positioned) in contact with the recess 202a.

  That is, in such an operation, the cam part 43/43 is brought into contact with the support member 50/50 of the transfer belt unit 8 and pushed up by rotating the entire separation / contact control unit 38 upward by closing the side cover 35. Is done.

  At this time, the support shaft 78a of the transfer belt unit 8 is pressed against and supported by the recess 202a by the pressing force of the elastic member 50a provided between the support member 50 and the housing 70.

  Here, for example, when the multi-color mode is set as the default state of the image forming mode, the cam portion 43 is in the state shown in FIG. 14, but in the single-color mode, the cam portion 43 is shown in FIG. It becomes a state.

  As shown in FIG. 3, the rotational movement of the entire separation / contact control unit 38 is performed by rotating the rotary bosses 51/51 provided on the frame members 49/49 (see FIG. 9) of the separation / contact control unit 38, which will be described later. It is rotatably supported by a hole provided in the connecting / disconnecting means supporting portion 204/204 extending downward from 201, and via sleeves 52/52 provided on the outer circumferences of both ends of the rotating shaft 48 of the connecting / detaching control portion 38. This is done by engaging the slope portions 181 and 181 at the bottom of the slide cams 18a and 18a.

  Notches are provided in the holes of the rotating bosses 51 and 51 provided in the separation control unit 38 and the separation means support portions 204 and 204 extending downward from the rail members 201 and 201, respectively. As a result, the attachment / detachment control unit 38 can be easily attached and detached from the side cover 35 side, and the assembling time is shortened and the assembling cost is reduced.

  Also, the release of the support of the transfer belt unit 8 is the reverse movement described above by opening (withdrawing) the side cover 35. That is, it can be performed by dropping the support shafts 78b and 78a of the transfer belt unit 8 in the rail grooves 203 and 203 of the rail members 201 and 201.

  This can be done by operating the lever to release the positioning of the transfer belt unit after opening the exterior, or by pulling out the transfer belt unit from the drawer unit after pulling out the drawer unit that supports the transfer belt unit, etc. It can be performed without using the operation and mechanism part.

  That is, the support of the transfer belt unit 8 is released only by opening the side cover 35, and it is possible to make the free state sufficiently separated from the photosensitive drum 3. Thereby, it is possible to remove the fastening state with a tool or the like without removing it from the image apparatus as it is, or to remove a sheet staying on the transfer belt 7 due to a jam or the like.

  Therefore, the image forming apparatus can be reduced in size and weight, and easy maintenance and cost reduction can be realized.

  Hereinafter, a stop member (blocking member) for locking the photosensitive drum 3 to the transfer belt unit 8 will be described with reference to FIGS. 5, 11, and 12.

  The image forming apparatus further includes a stop member 231. The stop member 231 is formed of a thin plate such as a steel plate, and is positioned between the inner side of the front frame 205 and the rail member 201, and can be slid up and down by a plurality of guide members of the rail member 201. The stop member 231 is always urged downward by elastic members 232.

  As described above, by closing the side cover 35, the slide cam 18a engages with the unit lift arm 211, and the slide cam 18b engages with the stop member lift arm 233 (see FIG. 11). As a result, the unit lift arm 211 and the stop member lift arm 233 rotate and move upward, push up the stop member 231, and cause the stop member 231 to protrude from the rail member 201.

  Accordingly, as shown in FIG. 12, convex portions 304 (304a, 304b, 304c, 304d) for preventing erroneous drawing provided in the process unit 303 (303a, 303b, 303c, 303d) including the photosensitive drum 3 are provided. Further, by interfering with the protruding portion of the stop member 231, it is possible to prevent the photosensitive drum 3 from being pulled out from the image forming apparatus. That is, the process unit 303 including the photosensitive drum 3 is protected from being pulled out from the image forming apparatus.

  Thus, the process unit 303 can be pulled out without opening the side cover 35, that is, when the transfer belt unit 8 is released from the support and the photosensitive drum 3 and the transfer belt 7 are not completely separated from each other. It is protected so that it does not.

  As a result, the drawing operation of the process unit 303 when the transfer belt 7 and the photosensitive drum 3 are in contact with each other can be prevented, and the photosensitive drum 3 and the transfer belt 7 are prevented from being damaged.

  On the other hand, by opening the side cover 35, as shown in FIG. 11, the engagement of the slide cams 18a and 18b with the corresponding unit lift arm 211 and stop member lift arm 233 is released. Thereby, the unit lift arm 211 and the stop member lift arm 233 rotate and move downward, the push-up of the stop member 231 is released, and the elastic member 232 that urges the lower side to release the tip (upper end) of the stop member 231. ) Is lower than the upper end of the rail member 201.

  Accordingly, the prevention of drawing out from the image forming apparatus applied to the convex portion 304 for preventing erroneous drawing of the process unit 303 including the photosensitive drum 3 is released, and the process unit 303 including the photosensitive drum 3 is removed. It can be pulled out.

  Thus, when the transfer belt 7 and the photosensitive drum 3 are in contact with each other, the process unit including the photosensitive drum 3 cannot be pulled out by mistake. Accordingly, it is possible to prevent the photosensitive drum 3 and the transfer belt 7 from being damaged.

  The transfer carrier device that can be attached to and detached from the image forming apparatus and includes a separation / contact mechanism is not limited to the transfer belt unit 8, and conveys a photosensitive belt, a document, a sheet, and the like. Therefore, the present invention can also be applied to a sheet conveying belt for the purpose.

  As described above, the separation / contact mechanism supports the transfer belt unit 8 in the separation / contact mechanism that removably supports the transfer belt unit 8 (contact member) with respect to the photosensitive drum 3 (carrier). A slide unit 18 that urges the transfer belt unit 8 toward the photosensitive drum 3 via the rail member 201 so that the rail member 201 (support member) and the transfer belt unit 8 abut against the photosensitive drum 3. A contact control unit 38 (biasing member). The rail member 201 further includes a recess 202a and a positioning hole 202b (positioning means) for positioning the transfer belt unit 8 when the transfer belt unit 8 and the photosensitive drum 3 are in contact with each other. Further, the support of the transfer belt unit 8 by the concave portion 202 a and the positioning hole 202 b is released by moving the slide portion 18 and the separation control unit 38 in one direction, and the transfer belt unit 8 is separated from the photosensitive drum 3. Can do.

  As a result, the transfer belt unit 8 can be easily brought into a free state simply by moving the slide unit 18 and the separation / contact control unit 38 in one direction. Therefore, the transfer belt unit 8 can be easily replaced.

  The separation / contact mechanism is a separation / contact mechanism that removably supports the transfer belt unit 8 (contact member) with respect to the photosensitive drum 3 (support), and a rail member 201 that supports the transfer belt unit 8. (A support member) and a slide unit 18 that urges the transfer belt unit 8 in the direction of the photosensitive drum 3 via the rail member 201 so that the transfer belt unit 8 contacts the photosensitive drum 3. 38 (biasing member). The rail member 201 includes positioning means (concave portion 202 a and positioning hole 202 b) for positioning the contact member when the transfer belt unit 8 and the photosensitive drum 3 are in contact, and the transfer belt unit 8 and the photosensitive drum 3. Are provided with a concave portion 202c and a convex portion 203a (position regulating means) for regulating the displacement of the transfer belt unit 8 with respect to the rail member 201 at the time of separation, and by the slide portion 18 / separation control portion 38 at the time of contact. The urged transfer belt unit is supported by the concave portion 202a and the positioning hole 202b, and is supported by placing the transfer belt unit 8 at the time of separation.

  Thereby, since the rail member 201 only mounts the transfer belt unit 8 at the time of separation (support by the rail member 201 is released), the transfer belt unit 8 can be in a free state. Therefore, the transfer belt unit 8 can be easily replaced.

  Further, when the support for positioning of the transfer belt unit 8 is released by the concave portions 202c and the convex portions 203a, and the transfer belt unit 8 is in a free state, the transfer belt unit 8 is not inadvertently displaced. Can do.

  Furthermore, for example, by positioning any one of the concave portion 202a and the positioning hole 202b and the concave portion 202c and the convex portion 203a, the positioning can be performed smoothly even in a free state.

  In the separation / contact mechanism, the rail member 201 (support member) preferably includes a rail groove 202 (guide groove) that allows the transfer belt unit 8 (contact member) to be attached and detached.

  Thereby, the transfer belt unit 8 can be easily replaced.

  That is, the image forming apparatus provided with the above-described separation / contact mechanism can be separated from / contacted to the photosensitive drum 3 (image carrier) on which an image is formed based on the image data. 3 is provided with a transfer belt unit 8 (transfer carrier device) having a transfer belt 7 (transfer carrier) for transferring the image by contacting with the belt 3.

  Then, the transfer belt unit 8 is separated from the photosensitive drum 3 by the operation of opening the side cover 35 (a part of the exterior) of the image forming apparatus. Alternatively, the transfer belt unit 8 is released from the support to the image forming apparatus main body by the operation of opening the side cover 35 (a part of the exterior) of the image forming apparatus.

  Therefore, the transfer belt 7 provided in the transfer belt unit 8 is completely separated from the photosensitive drum 3, and a sheet staying on the transfer belt unit 8 can be easily taken out due to a jam or the like.

  At this time, the transfer belt unit 8 may be in a free state, and if it is in a free state, only the transfer belt unit 8 can be easily taken out from the image forming apparatus as it is.

  Therefore, the release lever that separates the transfer belt unit 8 from the photosensitive drum 3 that is normally provided is not operated after the exterior is released, and the transfer belt unit 8 is not pulled out together with the separation mechanism after the release lever is operated. It will end. As a result, the number of steps for taking out the transfer belt unit 8 for jam handling work and maintenance can be reduced, and speedy work can be performed.

  Further, since the transfer belt unit 8 is not pulled out from the image forming apparatus together with the release lever and the separation mechanism, the image forming apparatus can be reduced in size and weight, and the manufacturing cost and the maintenance cost can be reduced. be able to.

  Further, the side cover 35 is an exterior parallel to the axes of the drive roller 73 and the tension roller 71 (roller member) that rotatably supports the transfer belt 7 of the transfer belt unit 8 in the exterior of the image forming apparatus. It is opened in the direction orthogonal to.

  That is, the side cover 35 is an exterior parallel to any one of the four surfaces excluding the frames 205 and 206 in the image forming apparatus. Therefore, it is not necessary to provide openings for attaching and detaching the transfer belt unit 8 to the frames 205 and 206, so that the strength of the frames 205 and 206 is not reduced. For this reason, it is not necessary to increase the thickness of the frames 205 and 206 to increase the strength thereof, so that the weight of the image forming apparatus can be reduced.

  In general, if the exterior is opened in a direction parallel to the axes of the drive roller 73 and the tension roller 71, particularly in the case of a tandem type image display device, the opening becomes large, and the strength of the frames 205 and 206 is reduced. Become.

  However, when the exterior of the transfer belt unit 8 is moved in a direction perpendicular to the axes of the drive roller 73 and the tension roller 71, compared with the case where the transfer belt unit 8 is moved parallel to the axes of the drive roller 73 and the tension roller 71, A mechanism for positioning and supporting the transfer belt unit 8 with respect to the image forming apparatus main body can be formed compactly.

  In addition, opening the exterior in a direction orthogonal to the axes of the drive roller 73 and the tension roller 71 that supports the transfer belt unit 8 opens the exterior toward the upstream side or the downstream side in the sheet conveyance direction. .

  Therefore, when a jam or the like occurs, it is possible to easily pull the jammed sheet upstream or downstream in the conveyance direction by grasping the leading edge or the trailing edge of the sheet. As a result, it is possible to prevent the sheet from being torn when being pulled out and leaving a torn piece of the sheet in a narrow area where a hand cannot be inserted.

  Hereinafter, the configuration of the transfer belt unit 8 will be described in detail with reference to FIGS. 4 and 16 to 19.

  As shown in FIG. 16, the transfer belt unit 8 includes a transfer belt 7 that is an endless belt, a transfer belt support unit (hereinafter referred to as a support unit) 81 that is a belt unit, and a transfer belt support unit that is a belt unit. (Hereinafter, referred to as a support unit) 82.

  The support unit 81 and the support unit 82 are connected to each other by a connecting portion 86 described later. When the support unit 81 and the support unit 82 are linearly connected in this manner, the transfer belt 7 is stretched on the support units 81 and 82.

  As shown in FIGS. 17A and 17B, both the support unit 81 and the support unit 82 have the same housing (base member) 70 as a base.

  Further, as shown in FIGS. 17A and 17B, the housing 70 includes a connecting portion 86 having a hole through which a fastening member such as a screw or a pin passes, and a belt tension which is a roller mounting portion for belt stretching. And a support shaft 78 functioning as a fulcrum part and a support part. Here, as shown in FIG. 16, among the support shafts 78, the support shaft of the support unit 81 is a support shaft 78a, and the support shaft of the support unit 82 is a support shaft 78b.

  Also, as shown in FIGS. 17A and 17B, in the housing 70, one of the belt stretching roller mounting portions 75 is disposed at one end of the housing 70, and a transfer belt drive roller 71 (FIG. 18) described later. (B)) or a transfer belt tension roller 73 (FIG. 18A) is attached.

  Further, as shown in FIG. 17B, a transfer roller is a portion to which a transfer roller is attached on the surface of the housing 70 that is a side (upper surface (front surface) side) facing an image forming station (see FIG. 4) described later. Roller mounting portions 76a and 76b are provided.

  On the other hand, as shown in FIG. 17A, transfer belt driven rollers 72 and 74 (see FIG. 4) are attached to the back surface (lower surface) of the housing 70 on the side opposite to the side facing the image forming station. A transfer belt driven roller mounting portion 77 and a belt stretching roller mounting portion 75 to which the transfer belt driving roller 71 and the transfer belt tension roller 73 (see FIGS. 18 and 22) are mounted are provided.

  Therefore, the support unit 81 and the support unit 82 can be formed by combining a plurality of parts with respect to the same housing 70.

  That is, as shown in FIG. 18A, the support unit 82 has a transfer belt tension roller (hereinafter referred to as a tension roller) 73 as a roller member and a transfer roller 6a as a roller member on the surface of the housing 70. -It has 6b and the fixed board 85 which is a connection member.

  The fixing plate 85 is provided on one side of the connecting portion 86 and has a hole through which a fastening member or the like passes or a screw hole to be screwed and fastened.

  The tension roller 73 is attached to the belt tension roller attaching portion 75 located at one end of the housing 70 (FIG. 17A), and the transfer rollers 6a and 6b are respectively provided with bearings 762 on the transfer roller attaching portions 76a and 76b. (See FIG. 22), for example, is movable up and down at right angles to the axial direction, and is biased upward (on the image forming station side) by, for example, a compression coil spring (elastic member) 763. .

  Further, as shown in FIG. 18B, the support unit 81 includes a transfer belt driving roller (hereinafter referred to as a driving roller) 71, which is a roller member, and transfer rollers 6c and 6d on the surface of the housing 70. And a fixed plate 85. Similarly to the above, the fixing plate 85 is provided on the same side as the connecting portion 86 of the housing 70 of the support unit 82, and has a hole through which a fastening member or the like passes or a screw hole to be screwed and fastened.

  The drive roller 71 is attached to the belt stretching roller attachment portion 75 located at one end of the housing 70 (FIG. 17B), and the transfer rollers 6c and 6d are respectively attached to the transfer roller attachment portions 76b and 76a. It is attached in the same manner as the support unit 82.

  Furthermore, transfer belt driven rollers 72 and 74 (see FIG. 4), which will be described later, are attached to the back surfaces of the housings 70 and 70 of the support units 81 and 82 by a transfer belt driven roller mounting portion 77. In the present embodiment, the tension roller 73 and the drive roller 71 also have a function as a belt stretching roller for stretching the transfer belt 7.

  These support units 81 and 82 are connected to each other by a connecting portion 86 at the end of the housing 70 shown in FIGS. 17A and 17B (FIG. 19A). At this time, as shown in FIG. 19A, the support unit 81 and the support unit 82 are configured such that the above-described surfaces of the housings 70 and 70 of the support units 81 and 82 constitute a single plane. The above-described back surface 70 constitutes one plane.

  That is, as shown in FIGS. 18A and 18B, the housing 70 of the support unit 81 is connected in a state where the housing 70 of the support unit 82 is rotated 180 degrees in the plane.

  Thereby, the fixing plate 85 provided in the support unit 81 is connected to the connecting portion 86 on the side of the support unit 82 where the fixing plate 85 is not provided, while the fixing plate 85 of the support unit 82 is connected to the support unit 81. Are connected to the connecting portion 86 on the side where the fixing plate 85 is not provided.

  More specifically, as shown by the arrows in FIGS. 19B and 19C, the connecting portion 86 of the support unit 81 including the fixing plate 85 is connected to the supporting unit 82 not including the fixing plate 85. 86 (FIG. 19B) is overlapped with the support unit 82 provided with the fixed plate 85, and the connecting unit 86 of the support unit 81 not provided with the fixed plate 85 (FIG. 19C). The two support units 81 and 82 are connected so as to overlap with each other.

  Then, as shown in FIGS. 19B and 19C, the two support units 81 and 82 are configured such that the fixing plate 85 and the connecting portion 86 are supported by a support fastening member (hereinafter referred to as a support member) through respective holes. And a step screw 84 which is a support fixing member (hereinafter referred to as a fixing member).

  Further, by removing the step screw 84 and loosening the fastening state of the step screw 83, each of the support units 81 and 82 can be rotated with the step screw 83 as a fulcrum.

  In the present embodiment, a step screw 83 is provided on the surface side (upper side in the drawing) of the housings 70 and 70 of the support units 81 and 82. For this reason, the support units 81 and 82 rotate with the stepped screw 83 as a fulcrum so that the surfaces of the respective housings 70 are close to each other, so that it is possible to form a substantially V-shaped bent state. ing.

  Then, as shown in FIG. 19A, when the support unit 81 and the support unit 82 are kept in a straight line, the support unit 81 is provided on the back side of the housing 70 (the lower side of FIG. 19C). The 82 fixing plate 85 and the connecting portion 86 are fixed by inserting and screwing the stepped screw 84. Further, by twisting and fixing the step screw 83, it can be reliably maintained in a straight line.

  The step screw 83 and the step screw 84 are the same fastening member. Thereby, a component kind can be reduced and the mass productivity at the time of manufacture can be improved. Further, when the step screws 83 and 84 are replaced with shaft members such as pins, the holes provided in the fixing plate 85 and the connecting portion 86 are not screw holes but have substantially the same hole diameter as the shaft diameter of the shaft members such as pins. Just make a hole.

  Moreover, since the hole provided in the connection part 86 is a hole of the internal diameter substantially the same as the outer diameter of the step part of step screw 83 * 84, a highly accurate connection can be performed. By fixing the corrugated screws 83 and 84 in a strong fastening state, the fixing plate 85 and the connecting portion 86 can be firmly fixed. On the other hand, by loosening the fastening state and removing one of the corrugated screws, the support unit 81. 82 can be pivotable.

  The step screws 83 and 84 may be different fastening members instead of the same fastening member, and may be fastening members such as ordinary screws instead of the step screws.

  Further, the stepped screw 83 is not limited to being provided in the connecting portion 86 on the surface side of the housing 70, and the stepped screw 83 is formed at a position serving as a fulcrum when the two support units 81 and 82 are V-shaped. A screw 83 may be provided.

  That is, when the back surfaces of the housings 70 of the support units 81 and 82 are bent so that they face each other, the step screw 83 may be provided at the position where the step screw 84 is installed.

  In this embodiment, the tension roller 73 attached to the belt stretching roller attachment portion 75 has a tension function. However, the present invention is not limited to this, and a transfer belt driven member described later attached to the belt driven roller attachment portion 77 is provided. The roller 72 may have a tension function.

  In addition, as shown in FIG. 16, the transfer belt unit 8 has no hindrance to the attachment / detachment of the transfer belt 7, and receives power for transmitting / receiving and receiving power on the side where the support shaft 78b that moves little when switching the image forming mode is located. A connector 240 is provided.

  As described above, since the support unit 81 and the support unit 82 have the same housing 70 and 70 as a base member, the sizes of both are substantially the same.

  For this reason, as shown in FIG. 16, the distance L2 from the step screw 83, which is the fulcrum of the connecting portion 86 of the support units 81, 82, to the tension roller 73, which is the tip of the support unit 81 (see FIG. 18A). The distance L1 from the step screw 83 to the driving roller 71 that is the tip of the support unit 82 is substantially equal.

  Further, as shown in FIG. 16, the transfer belt unit 8 is a straight line formed by combining two support units 81 and 82 having the same distances L1 and L2, and the transfer belt 7 surrounds both support units 81 and 82. It has a structure. Further, the transfer belt 7 is stretched by drive rollers 71 and tension rollers 73 located at both ends of the transfer belt unit 8.

  Hereinafter, the operation of attaching or detaching the transfer belt 7 to / from the support units 81 and 82 performed when the transfer belt 7 is replaced will be described with reference to FIGS.

  As shown in FIG. 16, the transfer belt unit 8 operates in a state where the transfer belt 7 is stretched and supported by the support units 81 and 82. Therefore, in order to make the transfer belt 7 stretched, first, the step screw 84 (see FIG. 19C) fixing the support units 81 and 82 is removed, and the step screw 83 is further loosened. After that, as shown in FIG. 20, the support units 81 and 82 are bent into a substantially V shape with the step screw 83 as a fulcrum.

  At this time, since the step screw 83 is provided on the surface side of the housing 70 of the support units 81 and 82, the support unit 81 and the support unit 82 are bent so that the surfaces approach each other.

  Next, as shown in FIG. 20, the transfer belt 7 is covered on the support units 81 and 82 having a substantially V shape from the direction indicated by the arrow so as to cover the periphery. At this time, since the support units 81 and 82 are folded, they fall within a circle formed by the transfer belt 7.

  Then, with the stepped screw 83 as a fulcrum, the surface of the support units 81 and 82 is turned away (the direction opposite to the bending direction). As a result, the support units 81 and 82 are aligned, and the transfer belt 7 is stretched and supported by the support units 81 and 82 as shown in FIG.

  At this time, the driving roller 71 and the tension roller 73 are positioned at both ends of the transfer belt unit 8. Then, the transfer belt 7 can be stretched by applying tension to the transfer belt 7 by a tension member 79 (see FIG. 4) made of a coil spring or the like provided on the tension roller 73.

  Further, when the support units 81 and 82 are in a straight line, the two support units 81 and 82 are fixed by the step screws 84 to enable the transfer belt 7 to be held in a stretched state.

  Further, at this time, the transfer rollers 6a, 6b, 6c and 6d (see FIG. 19A) push up the transfer belt 7, but 6b and 6c are slightly more than the line connecting the upper surface of the drive roller 71 and the tension roller 73. 6a and 6d push the transfer belt 7 higher than 6b and 6c. Accordingly, 6b and 6c are not in contact with the back surface of the transfer belt 7.

  This is because the heights of the bearing restricting portions of the transfer roller mounting portions 76b and 76a for mounting the bearings 762 that rotatably support the transfer rollers 6a to 6d are different (see FIG. 22). The height of the bearing restricting portion will be described in detail later.

  As described above, in the support units 81 and 82, L1 and L2 shown in FIGS. 16 and 20 have substantially the same length, so that the transfer belt 7 can be easily attached to or detached from the support units 81 and 82. ing. This is because when the support units 81 and 82 are substantially V-shaped, the circumference of the circle surrounding the support units 81 and 82 is minimized when L1 and L2 are equal.

  That is, in the present embodiment, since L1 and L2 are substantially the same length, the support units 81 and 82 are formed around the support units 81 and 82 formed when the support units 81 and 82 are substantially V-shaped. The length of the surrounding circle (hereinafter referred to as the substantially outer circumference of the support units 81 and 82) can be minimized.

  Therefore, the difference between the peripheral length of the transfer belt 7 and the substantially outer periphery of the support units 81 and 82 becomes large, and the transfer belt 7 can be easily attached and detached.

  In order to specifically show the difference between the circumferential length of the transfer belt 7 and the substantially outer circumference of the support units 81 and 82, the support units 81 and 82 in which L1 and L2 are about 165 mm are described below, and the circumference is 730 mm. A case where a certain transfer belt 7 is used will be described as an example with reference to FIG. It is assumed that the thickness of the support units 81 and 82 indicated by W in FIG. 21 is about 35 mm.

  As shown in FIG. 16, when the support units 81 and 82 are in a straight line, the outer periphery thereof is equal to the peripheral length of the transfer belt 7 so that the transfer belt 7 can move on the support units 81 and 82. Then, the transfer belt 7 is stretched.

  On the other hand, as shown in FIG. 20, when the support units 81 and 82 are substantially V-shaped, the tension of the transfer belt 7 is relaxed. Thus, as shown in FIG. 21, when the transfer belt 7 is circular, the diameter D of the transfer belt 7 is about 233 mm.

  At this time, as shown in FIG. 21, if the internal angle α formed by the support unit 81 and the support unit 82 is 60 degrees, the lengths L1 and L2 of the support units 81 and 82 form two sides of an equilateral triangle. . That is, L1, L2, and L3 in FIG. 21 all have the same length. Therefore, since this equilateral triangle has a side length of 165 mm, the diameter of the circumscribed circle of the equilateral triangle shown by the alternate long and short dash line in FIG. 21 is about 190.5 mm. Here, L3 indicates the remaining one side with the support units 81 and 82 as two sides of the triangle.

  On the other hand, since the support units 81 and 82 include the drive roller 71 and the tension roller 73 (see FIGS. 18A and 18B), it is considered that the support units 81 and 82 are actually slightly larger than about 190.5 mm.

  In view of the outer shape of the drive roller 71 and the tension roller 73 and the thickness W (FIG. 21) of the support units 81 and 82, the approximate outer circumference formed by the support units 81 and 82 is calculated. It is considered to be about 220 mm.

  As described above, the diameter D of the transfer belt 7 is about 233 mm, which is sufficiently larger than the substantially outer periphery (220 mm) formed by the support units 81 and 82. Therefore, since the folded support units 81 and 82 can be accommodated in the transfer belt 7 as shown in FIG. 20, the transfer belt 7 can be easily attached and detached, and the operation when replacing the transfer belt 7 is performed. Improves.

  The smaller the inner angle α formed by folding the support unit 81 and the support unit 82, the better. However, in order to set α to 0 degree, it is necessary to provide the connecting portion 86 so as to protrude to the back side of the support units 81 and 82 when the support units 81 and 82 are aligned.

  For this reason, in the present embodiment, α is set to about 60 degrees as an angle at which the connecting portion 86 does not need to protrude when the support units 81 and 82 are aligned.

  Hereinafter, the configuration of the image forming apparatus including the transfer belt unit 8 described above will be described with reference to FIG.

  Here, the image forming apparatus shown in FIG. 4 is generally provided in a copying machine or the like including the image forming apparatus and the paper feeding device shown in FIG.

The image forming apparatus forms multicolor and single color images on a predetermined sheet (recording medium) in accordance with image data transmitted from the outside. The image forming apparatus includes an exposure unit 1 (1a to 1d), a developing device 2 (2a to 2d), a photosensitive drum 3 (3a to 3d), a charger 5 (5a to 5d), and a cleaner unit 4 (4a). 4d), the transfer belt unit 8, the fixing unit 12, the sheet conveying path S, the paper feed tray 10, the paper discharge trays 15 and 33, and the like. Note that image data handled in the image forming apparatus is black (K ), Cyan (C), magenta (M), and yellow (Y).

  Accordingly, the exposure unit 1 (1a, 1b, 1c, 1d), the developing device 2 (2a, 2b, 2c, 2d), the photosensitive drum 3 (3a, 3b, 3c, 3d), and the charger 5 (5a, 5b, 5c, 5d), and four cleaner units 4 (4a, 4b, 4c, 3d) are provided to form four types of latent images corresponding to the respective colors, a being black, b being cyan, Four image forming stations are configured with c set to magenta and d set to yellow.

  The photosensitive drum 3 is disposed (attached) at substantially the center of the image forming apparatus, and has a photosensitive member on the surface thereof. The photosensitive drum 3 has a drum shape and is driven to rotate. Around the photosensitive drum 3, a charger 5, a developing device 2, a transfer roller 6, and a cleaner unit 4 are arranged along the rotation direction.

  The charger 5 is a charging means for uniformly charging the surface of the photosensitive drum 3 to a predetermined potential. In addition to a contact-type roller type and a brush type charger, a charger type as shown in FIG. The charger is used.

  Although the LED writing head is used as the exposure unit 1, it is not limited to this. For example, an EL (electroluminescence) in which light emitting elements are arranged in an array, or a laser including a laser irradiation unit and a reflection mirror. A scanning unit (LSU) or the like may be used.

  The exposure unit 1 has a function of forming an electrostatic latent image corresponding to the image data on the surface thereof by exposing the charged photosensitive drum 3 according to the input image data.

  The developing device 2 visualizes the electrostatic latent images formed on the respective photosensitive drums with (K, C, M, Y) toner.

  The cleaner unit 4 removes and collects toner remaining on the surface of the photosensitive drum 3 after development and image transfer.

  As described above, the transfer belt unit 8 disposed below the photosensitive drum 3 includes the two support units 81 and 82 (see FIG. 16). That is, the transfer belt unit 8 includes a transfer belt 7, a driving roller 71, a tension roller 73, transfer belt driven rollers 72 and 74, and a transfer roller 6 (6a, 6b, 6c, and 6d). A transfer belt cleaning unit 9 is provided adjacent to the transfer belt unit 8.

  The drive roller 71, the tension roller 73, the transfer roller 6, the transfer belt driven rollers 72, 74, and the like stretch the transfer belt 7 and rotate the transfer belt 7 in the direction of arrow B.

  The transfer roller 6 is rotatably supported by transfer roller mounting portions 76 a and 76 b of the housing 70 of the transfer belt unit 8, and the toner image (image) of the photosensitive drum 3 is attracted onto the transfer belt 7 and conveyed. A transfer bias for transferring to a sheet (recording member) to be transferred is provided.

  The transfer belt 7 is formed endlessly using a film having a thickness of about 100 μm to 150 μm, is provided so as to come into contact with each photosensitive drum 3, and each color formed on the photosensitive drum 3. The toner images are sequentially superimposed on the sheet and transferred to form a color toner image (multicolor toner image).

  Transfer of the toner image from the photosensitive drum 3 to the sheet is performed by the transfer roller 6 that is in contact with the back side of the transfer belt 7. A high voltage transfer bias (a high voltage having a polarity (+) opposite to the toner charging polarity (−)) is applied to the transfer roller 6 in order to transfer the toner image.

  The transfer roller 6 is a roller whose base is a metal (for example, stainless steel) shaft having a diameter of 8 to 10 mm and whose surface is covered with a conductive elastic material (for example, EPDM, urethane foam, or the like). By this conductive elastic material, a high voltage can be uniformly applied to the sheet. In this embodiment, the transfer roller 6 is used as the transfer electrode, but a brush or the like may be used in addition to that.

  Further, the toner adhering to the transfer belt 7 due to contact with the photosensitive drum 3 is set to be removed and collected by the transfer belt cleaning unit 9 in order to cause the back surface of the recording paper to become dirty. The transfer belt cleaning unit 9 includes a cleaning blade as a cleaning member that contacts the transfer belt 7, for example, and the transfer belt 7 that contacts the cleaning blade is supported by a transfer belt driven roller 74 from the back side.

  The paper feed tray 10 is a tray for storing sheets used for image formation, and is provided below the image forming unit of the image forming apparatus. A paper discharge tray 15 provided on the upper portion of the image forming apparatus is a tray on which printed sheets are placed face down, and a paper discharge tray provided on a side portion of the image forming apparatus. The tray 33 is a tray for placing the image-formed sheet face up.

  In addition, the image forming apparatus is provided with an S-shaped sheet conveyance path S for sending the sheets in the paper feed tray 10 to the paper discharge tray 15 via the transfer conveyance unit 8 and the fixing unit 12. Yes. Further, in the vicinity of the sheet transport path S from the paper feed tray 10 to the paper discharge tray 15 and the paper discharge tray 33, a pickup roller 16, a paper feed transport roller 23, a registration roller 14, a fixing unit 12, and a transport direction switching guide 34 are provided. Further, conveying rollers 26, 24, and 27 for conveying the sheet, a discharge roller 25, and the like are arranged.

  The pickup roller 16 is provided at the end of the paper feed tray 10 and is a calling roller that feeds sheets one by one from the paper feed tray 10 toward the paper feed conveyance roller 23 in the sheet conveyance path S.

  The conveyance direction switching guide 34 is rotatably provided on the side cover 35, and separates the sheet from the middle of the conveyance path S by discharging from the state indicated by the solid line to the state indicated by the broken line and discharges the sheet to the paper discharge tray 33. It can be done. In the state indicated by the solid line, the sheet passes through the conveyance unit S ′ (a part of the sheet conveyance path S) formed between the fixing unit 12, the side cover 35, and the conveyance switching guide 34, and the upper discharge tray. 15 is discharged by a paper discharge roller 25.

  Further, the registration roller 14 temporarily holds the sheet being conveyed through the sheet conveyance path S. The sheet has a function of transporting the sheet with good timing in accordance with the rotation of the photosensitive drum 3 so that the toner image on the photosensitive drum 3 can be satisfactorily transferred onto the sheet.

  That is, the registration roller 14 conveys the sheet so that the leading edge of the toner image on each photosensitive drum 3 is aligned with the leading edge of the image forming range on the sheet based on a detection signal output from a pre-registration detection switch (not shown). Is set to

  The fixing unit 12 includes a heat roller 31, a pressure roller 32, and the like, and the heat roller 31 and the pressure roller 32 rotate with a sheet interposed therebetween.

  The heat roller 31 is set by the control unit to have a predetermined fixing temperature based on a signal from a temperature detector (not shown), and is transferred to the sheet by thermocompression bonding the sheet together with the pressure roller 32. The resulting multicolor toner image is melted, mixed, and pressed to thermally fix the sheet.

  The sheet after the fixing of the multicolor toner image is transported through the reverse paper discharge path of the sheet transport path S by the transport rollers 26, 27, and 24, and in a reversed state (with the multicolor toner image facing downward). ) The paper is discharged onto the paper discharge tray 15 by the paper discharge roller 25.

  Hereinafter, the separation / contact operation of the transfer belt unit 8 with respect to the image forming station will be described.

  First, the relationship between the separation / contact operation and the transfer roller 6 will be described.

  The support shafts 78 (78a and 78b) shown in FIG. 17 function as rotating shafts and positioning members when the transfer belt unit 8 is moved away from or in contact with the image forming station. As shown in FIGS. 17 and 18, the support shaft 78 is formed in the housing 70, and is substantially on the extension of the axis of the transfer roller 6 a. One support shaft 78 is formed on each side of each of the support unit 81 and the support unit 82, that is, two support shafts 78 are formed on each unit.

  As shown in FIG. 3, the support shafts 78a and 78b are provided on rail members 201 and 201 provided inside the front frame 205 and the rear frame 206, which are frame members (see FIG. 15) of the main body of the image forming apparatus. . That is, the support shaft 78b is fitted into the positioning hole 202b at a position that serves as a rotation fulcrum, and the support shaft 78a is pressed against the concave portion 202a for positioning.

  As a result, the transfer belt unit 8 is positioned with respect to the rail members 201 and 201, and the support shaft 78b becomes a rotation shaft in the positioning holes 202b and 202b. As described above, the transfer belt unit 8 is supported by the positioning holes 202b and 202b and is rotatable about the support shaft 78b as a rotation axis.

  FIG. 22 is an enlarged view in which the transfer belt 7 is added to the FF partial cross section and the GG partial cross section shown in FIG. As shown in FIG. 22, the transfer roller 6 a is rotated by bearings 762 and 762 that are vertically movable on bearing support portions 761 and 761 of transfer roller mounting portions 76 a and 76 a formed in the housing 70 of the support unit 82. Supported and movable up and down.

  Further, the transfer roller mounting portion 76a is urged toward the transfer belt 7 (upward) by, for example, a compression coil spring 763. Accordingly, the transfer roller mounting portions 76a and 76a are configured such that the shaft center of the transfer roller 6a is loosely fitted, and the shaft center of the transfer roller 6a can move up and down.

  As a result, even if the transfer belt unit 8 performs a separation / contact operation for switching the image forming mode, the transfer roller 6a can move up and down independently of the support shaft 78b, and the contact between the transfer belt 7 and the photosensitive drum 3a. The state is always kept stable, and a predetermined nip width and a predetermined pressing force can be maintained.

  At this time, the shaft centers of the support shafts 78b and 78b are positioned on a line substantially equal to the line obtained by extending the shaft center of the transfer roller 6a, so that the transfer belt unit 8 switches the image forming mode. Even when the transfer is performed, the function of the transfer roller 6a is not impaired (see FIG. 5).

  On the other hand, the other transfer rollers 6b, 6c, and 6d are also movable up and down independently of the transfer roller mounting portions 76b and 76b or the transfer roller mounting portions 76a and 76a, similarly to the transfer roller 6a.

  Thus, as shown in FIG. 6B, in the image forming mode (multicolor mode) in which the transfer belt 7 is in contact with the photosensitive drums 3a to 3d, the transfer belt 7 and all the photosensitive drums 3a to 3d. Can be maintained with a predetermined nip width and a predetermined pressing force.

  Further, as shown in FIG. 22, the transfer roller mounting portions 76a and 76b are provided with regulating members 764a and 764b for regulating the free height of the transfer roller 6, respectively. When the photosensitive drum 3 and the transfer belt 7 are brought into a non-contact state by engaging the transfer roller 6 with a hooking portion 765 of a bearing 762 that is rotatably and vertically movable, the transfer roller 6 6 free height is regulated. The restriction member 764 is formed so that the amount of restriction differs between the transfer roller mounting portions 76a and 76b.

  That is, the free height of the regulating member 764a formed on the transfer roller mounting portion 76a is set to be higher than the free height of the regulating member 764b formed on the transfer roller mounting portion 76b, and the transfer roller 6a. , 6d is set to be higher than the driving roller 71 and the tension roller 73 located at both ends of the transfer belt unit 8.

  Here, the difference D in the free height between the transfer rollers 6a and 6d and the transfer rollers 6b and 6c is set to 1.5 to 3 mm. However, the present invention is not limited to this. What is necessary is just to make the difference which roller 6b * 6c does not contact.

  6A, when the support of the transfer belt unit 8 is released, the transfer rollers 6a and 6d are positioned higher than the drive roller 71 and the tension roller 73 located at both ends, and the transfer roller The positions 6b and 6c are lower than the transfer rollers 6a and 6d, and the photosensitive drum 3 is not in contact with the transfer belt 7.

  At this time, the distance between the transfer belt 7 and the surface of the photosensitive drum 3 is about 12 mm, and the surface of the photosensitive drum 3 and the surface of the transfer belt 7 are sufficiently separated from each other. Accordingly, when the photosensitive drum 3 is replaced or when the transfer belt 7 is replaced, it is possible to pull out the unit including each without interference.

  As described above, the difference in the free heights of the transfer rollers 6a to 6d is as shown in FIG. 6C in the image forming mode (monochrome mode) in which the photosensitive drums 3b, 3c, and 3d are not used. The contact force between the transfer rollers 6 b to 6 d corresponding to the photosensitive drums 3 b to 3 d not used for image formation and the transfer belt 7 is reduced, and in particular, the transfer rollers 6 b and 6 c positioned at the center portion of the transfer belt unit 8. This is because the contact force with respect to the transfer belt 7 is extremely reduced.

  For example, if the transfer rollers 6 a to 6 d have the same height, the transfer rollers 6 b and 6 c cannot be rotated by the frictional force with the transfer belt 7 when the transfer belt 7 is rotated. As a result, uneven wear of the transfer rollers 6b and 6c occurs, causing troubles such as a decrease in the life of the transfer rollers 6b and 6c and uneven transfer.

  In the image forming mode in which there is an image forming portion (image forming station) that does not operate as in the single color mode, the transfer rollers 6b and 6c positioned at the central portion of the transfer belt unit with the separation and contact of the transfer belt unit 8 Since the contact with the transfer belt 7 is released, abnormal wear (uneven wear) of the transfer roller 6 can be prevented, the life of the transfer roller 6 can be extended, and good image formation can be maintained over a long period of time.

  As described above, in order to solve the above-described problem, the image forming apparatus can be separated from and contacted with the photosensitive drum 3 on which the image is formed based on the image data, and the transfer roller ( A transfer belt unit 8 having a transfer belt 7 to which a voltage is applied by a transfer member) and transferring the image. A plurality of photosensitive drums 3 are arranged in a direction orthogonal to the axes of the drive roller 71 and tension roller 73 (roller member) that rotatably support the transfer belt 7, and all the plurality of photosensitive drums 3 are attached to the transfer belt 7. An image forming mode (multi-color mode) used in contact with an image, and an image forming mode (monochromatic mode) in which any one of the plurality of photosensitive drums 3 is brought into contact with the transfer belt 7 and used. Have When the monochrome mode is selected, the transfer rollers 6b and 6c corresponding to the photosensitive drum 3 that is not used and at least the transfer rollers 6a and 6d located at the end portions are not in contact with the transfer belt 7. It is comprised so that it may become a state.

  Usually, in an image forming mode (single color mode) using a specific photosensitive drum 3 (here, photosensitive drum 3a), transfer rollers 6b to 6d corresponding to the photosensitive drums 3b to 3d not used for image formation are provided. The contact force with the transfer belt 7 is reduced, and particularly the contact force between the transfer rollers 6b and 6c excluding the transfer roller 6d located at the end and the transfer belt 7 is extremely reduced. Therefore, the transfer rollers 6b and 6c corresponding to the unused photosensitive drum 3 and at least the transfer rollers 6a and 6d positioned at the end cannot be rotated by the frictional force with the transfer belt 7. In this case, uneven wear of the transfer roller 6 that cannot be rotated occurs, and as a result, troubles such as a reduction in the life of the transfer roller 6 and uneven transfer occur.

  However, according to the above-described configuration, the transfer rollers 6b and 6c are not in contact with the transfer belt 7, so that these problems can be prevented and good image formation can be maintained for a long time. be able to.

  Further, the transfer roller 6b or the transfer rollers 6b and 6c may be configured to be lower than the driving roller 71 so as not to contact the transfer belt 7.

  Since the transfer roller 6d located at the end is close to the drive roller 71 and has a high free height, the contact force with the transfer belt 7 can be maintained to some extent in order to push up the transfer belt 7. Therefore, the rotation operation by friction with the transfer belt 7 can be obtained almost normally without being pressed against the photosensitive drum 3d.

  Here, the angle difference (separation angle range) θ (see FIG. 8) between the multicolor mode and the single color mode of the transfer belt unit 8 is the same as that of the image forming station corresponding to the transfer roller 6b that is not used in the single color mode. The separation distance between the photosensitive drum 3b and the transfer belt 7 is set to be about 2.5 to 4 mm. This angle θ varies depending on the setting of the separation distance from the interval between the photosensitive drums 3 and is set to be 2 to 3 degrees here.

  The angle θ is not particularly limited, but the separation distance between the photosensitive drum 3b adjacent to the photosensitive drum 3a that contacts the transfer belt unit 7 and the transfer belt 7 in the monochromatic mode disturbs the recorded image. It is sufficient that the distance between the sheet and the end of the sheet to be conveyed is not in contact with the photosensitive drum 3b.

  The angle θ is short for switching the image forming mode, and the sheet is transferred to and from adjacent functional parts (the fixing unit 12 and the registration roller 14 in the present embodiment) that deliver the conveyed sheet. Since it can be performed smoothly, the smaller one is preferable.

  However, it is preferable that the angle θ is as small as possible. However, in the system in which the transfer is performed by transporting the sheet to the transfer belt 7, the sheet is supplied to the transfer belt 7 when the sheet is separated from the transfer belt 7 or vice versa. At times, it is necessary to pay attention because the sheet conveyance may be hindered if the sheet height differs greatly in each mode.

Here, the relationship between the separation distance between the photosensitive drum 3b and the transfer belt 7, the rubbing between the photosensitive drum 3b corresponding to the transfer roller 6b and the end of the sheet, and transfer failure (retransfer) is shown in the following table. It is shown in 1. Thereby, it is preferable that the said separation distance shall be 2.5-4 mm. Here, in Table 1, “◯” is always good, “Δ” is sometimes bad, and “x” is always bad. The basis weight in the normal sheet is 81~105g / m ^2.

  That is, as shown in Table 1, when the distance between the photosensitive drum 3b and the transfer belt 7 is 2.5 mm or more, any sheet has a problem with rubbing against the end of the sheet and transfer failure (retransfer). It turns out that there is no.

  Moreover, although the experiment under the condition setting exceeding 4 mm is not performed in the experimental results shown in Table 1, it can be predicted that there is no problem with respect to the above items exceeding 4 mm. However, it is conceivable that troubles may occur when the sheet is conveyed from the transfer belt 7 to the next process, the size of the image forming apparatus becomes large, and the separation distance is preferably 4 mm or less.

  Next, control of the separation / contact operation in the transfer belt unit 8 will be described.

  When separating the transfer belt 7 from the rotating photosensitive drum 3 at the time of conversion between image forming modes (multicolor mode and single color mode), a separation operation is performed while rotating both at a constant speed. The rotation of the drum 3 is stopped after the transfer belt unit 8 completes the lowering and the transfer belt 7 is completely separated from the photosensitive drum 3 (3b to 3d). The image forming mode can be switched even when both operations are stopped.

  7 to 10 show the configuration of the separation control unit 38 for moving the transfer belt unit 8 to and from the photosensitive drum 3.

  As shown in FIG. 10, the separation / contact control unit 38 includes a drive source (separation / contact drive motor) 39, a gear transmission mechanism 40 for transmitting a driving force from the drive source 39, and the gear transmission mechanism 40. The cam gear 41 includes a cam portion 43 that is rotationally driven and has a cam portion 43 that slides and mounts a support member 50 (see FIG. 9) fixed to both lower portions of the downstream portion of the transfer belt unit 8. A frame member 49 is disposed between the drive source 39 and the gear transmission mechanism 40.

  The gear transmission mechanism 40 is attached to the frame member 49, and includes a drive gear 44 fixed to the output shaft of the drive source 39, an intermediate gear 45 that meshes with the drive gear 44, and a driven gear 46 that meshes with the intermediate gear 45. ing. In place of the gear transmission mechanism 40, a winding transmission mechanism including a belt, a pulley, or the like may be used.

  The driven gear 46 is fitted on the rotary shaft 48 via a one-way clutch (one-way clutch) 47 shown in FIG. Both side portions of the rotating shaft 48 are rotatably supported by frame members 49 and 49 of the main body of the separation control unit 38, and a pair of cam gears 41. 41 is fixed.

  The cam gear 41 is formed of a resin such as POM (polyacetal) having self-lubricating properties. As shown in FIGS. 7 and 8, the cam gear 41 is formed by integrating a partial gear 42 formed in a fan shape and a cam portion 43. A torque limiter 53 that meshes with the partial gear 42 is provided on one frame member 49, and the cam member 43 has support members 50, 50 projecting downward at the lower portions on both sides of the downstream portion of the transfer belt unit 8. Is in sliding contact.

  The support member 50 is supported by a housing 70 of a support unit 81 constituting the transfer belt unit 8 so as to be vertically movable, and is urged so as to push up the transfer belt unit 8 by an elastic member 50a made of a compression coil spring or the like. (See FIG. 3).

  As shown in FIG. 10, a sensor blade 41a is integrally formed in one cam gear 41, and its position state is detected by a detector 41b provided on the image forming apparatus main body side. It is like that.

  A torque limiter 53 shown in FIG. 10 includes two washers such as a flat washer (polyslider) made of resin and the like, a compression spring 53a sandwiched between the washers, a brake gear 53b, and the like, and includes a transfer belt unit. 8 is provided for buffering and regulating the descending operation of 8 and stably maintaining the position state at the lowest point.

  The load torque at the rotating shaft 48 of the cam gear 41 is 6.5 kgfcm, and the braking force of the torque limiter 53 is set to be 1.2 to 1.6 kgfcm at the rotating shaft 48 of the cam gear 41.

  The reason why the braking force is set to be small in this way is to prevent the braking force from acting on the drive source 39, and the direction of the solid arrow of the driven gear 46 by the one-way clutch 47 (see FIG. 9). Therefore, the cam gear 41 is set slightly ahead of the rotation of the drive source 39 due to the load applied to the cam portion 43.

  With the above configuration, for example, as shown in FIG. 7, the transfer belt unit 8 that was initially in the upper position (multicolor mode) in contact with all the photosensitive drums 3 a to 3 d is rotated forward ( The cam gear 41 rotates 180 degrees in the direction indicated by the solid arrow. As a result, as shown in FIG. 8, the downstream side of the transfer belt unit 8 moves downward with the axis of the support shaft 78b as the center of rotation, and is separated from the photosensitive drums 3b to 3d. That is, the monochrome mode in which only the photosensitive drum 3 a is in contact with the transfer belt unit 8 can be set.

  At this time, the partial gear 42 of the cam gear 41 is engaged with the brake gear 53b of the torque limiter 53, so that a braking force is applied. As a result, the forward rotation of the cam gear 41 is buffered and restricted, and the lowering operation of the transfer belt unit 8 is buffered and smoothly guided to the lowest point position.

  When the monochrome mode is set as the default state, the partial gear 42 does not mesh with the brake gear 53 b of the torque limiter 53 when the cam portion 43 is at the uppermost point. On the other hand, when the cam portion 43 is at the lowest point, only one tooth of the partial gear 42 meshes with the brake gear 53b of the torque limiter 53, and the transfer belt 7 floats carelessly in the default state of the transfer belt unit 8. In order to prevent this, a braking force acts and the transfer belt 7 is stably held.

  Since the load of the transfer belt unit 8 is configured to be directed in the direction of the rotation axis of the cam gear 41 (vertically downward), even when the cam portion 43 of the cam gear 41 is at the uppermost point (multicolor mode), the transfer is performed. A force for rotating the cam gear 41 is not generated by the load of the belt unit 8, and the transfer belt unit 8 is stably held.

  By adopting a stepping motor as a drive source 39 for performing the separation / contact operation of the transfer belt unit 8 and a drive source for rolling the photosensitive drum 3 and the transfer belt 7, speed control is achieved. In addition, the position control can be performed with high accuracy in an open loop, and the timing of each operation can be easily and appropriately taken.

  In particular, in the present embodiment, the driving force from the driving source 39 is transmitted to the auger 37 via another gear train 55 and collected from the transfer belt 7 by the transfer belt cleaning unit 9 (see FIG. 4). The toner thus collected can be conveyed and collected in the toner storage 36.

  As shown in FIG. 9, the gear train 55 includes a transmission gear 56 that meshes with the drive gear 44 of the drive source 39, an intermediate gear 57 that meshes with the transmission gear 56, and a driven gear 58 attached to one end of the auger 37. Become. The transmission gear 56 and the intermediate gear 57 are supported by a connecting movable arm 60 pivotally supported by a frame member 49, and are always urged in the meshing direction by an urging member (not shown).

  As a result, the meshed state between the driven gear 58 that moves up and down with the vertical movement of the transfer belt unit 8 and the intermediate gear 57 is ensured.

  Here, the load applied to the cam portion 43 of each cam gear 41 is set to 5 kgf, and a total load of 10 kgf by the transfer belt unit 8 is shared and supported by the cam portions 43 of the left and right cam gears 41. In addition, the range in which the teeth of the partial gear 42 of the cam gear 41 are formed is 150 degrees here, but may be appropriately changed according to the design conditions.

  With the above-described configuration, when the transfer belt unit 8 is lowered, the driving force of the driving source 39 that rotates clockwise (in the direction of the arrow indicated by the dotted line in FIG. 10) causes the driving gear 44 shown in FIG. The driven gear 58 rotates counterclockwise (in the direction indicated by the dotted line in FIG. 10). Accordingly, the auger 37 integrated with the driven gear 58 can be rotated in the same direction, and the toner collected from the transfer belt 7 can be conveyed and collected toward the toner collection container 36. That is, the driving force of the driving source 39 is also used as a driving force for rotating the auger 37, and the effective use thereof is intended.

  The toner remaining on the transfer belt 7 is directly transferred from the photosensitive drum 3 onto the transfer belt 7 for the control of the image forming process performed for maintaining the image quality, or the toner adhered due to trouble such as sheet conveyance jam. In other words, the toner of the patch image or the scattered toner floating in the multicolor image forming apparatus adheres to the transfer belt. By removing these toners at an appropriate timing (when the image forming mode is changed) as described above, stable image quality can be ensured.

  In this embodiment, since the auger 37 is formed of a spiral member, the toner is conveyed in the axial direction. However, the blade is attached in the axial direction, and the toner is supplied in a direction perpendicular to the axial direction. It is good also as a structure to scrape. In this case, a simple square or the like can be used.

  The auger 37 rotates in the reverse direction when the transfer belt unit 8 is separated and attached. However, since the frequency of the reverse rotation operation is small and is short, in the present embodiment, the auger 37 rotates in the reverse direction. Is an acceptable structure.

  However, when the reverse rotation operation of the auger 37 becomes a problem, the driven gear 58 may be attached to the rotation shaft 48 of the auger 37 via a one-way clutch (one-way clutch). In order to suppress an increase in the cost of the apparatus, a structure that allows reverse rotation of the auger 37 may be adopted.

  As a result, the drive source 39 of the separation / contact control unit 38 not only causes the transfer belt unit 8 (transfer belt 7) to separate / contact the photosensitive drum 3, but also drives the auger 37 to convey the collected toner. Therefore, the driving force of the driving source can be used effectively, and cost performance with excellent economic efficiency can be realized.

  Hereinafter, power supply and communication to the transfer belt unit 8 will be described with reference to FIGS. 1, 2, 13, and 14.

  The transfer belt unit 8 is a test that is formed on the transfer belt 7 so that the image quality of the image to be formed is always good, such as a drive source such as a stepping motor that rotates the drive roller 71 and rotates the transfer belt 7. Detector for detecting the density of the patch to control the process, and image formation as a reference so that a good image without color misregistration can be formed in the multicolor mode by aligning the position of the image formed at each image station A detector for detecting a test image formed on the transfer belt 7 in order to obtain a correction value for correcting the timing of forming the image of another image station with respect to the image of the station (the above-mentioned detector for process control) Or a transfer roller 6 to which a transfer bias is applied from a high voltage power source (not shown) or a transfer belt that requires grounding. And a roller member such as, for example, the tension roller 73 except the transfer roller 6 to touch.

  For this reason, electrical connection for performing power supply from various power sources and communication with a control unit or the like is necessary. In order to perform this electrical connection, as shown in FIGS. 1 and 2, the image forming apparatus includes a power supply connector 241 for performing transmission / reception and power supply on the image forming apparatus main body side.

  On the other hand, the transfer belt unit 8 is provided with a power receiving connector 240 for performing transmission / reception and power reception on the side where the support shaft 78b is located so that there is no hindrance to the attachment / detachment of the transfer belt 7 and the movement is small when the image forming mode is switched.

  The power feeding connector 241 includes a connector portion and a connector support portion. A slide hole 241a having a size larger than the thickness of the slide shaft that allows sliding movement with respect to the slide shaft 242 and a size that allows connection is provided in the connector support portion. That is, since the transfer belt unit 8 is inclined according to the image forming mode, the slide hole 241a is provided so as to cope with this inclination.

  Further, the power supply connector 241 is biased by an elastic member 243 made of a compression coil spring or the like so as to be positioned at the lower side, that is, the height of the power receiving connector 240 in the free state in which the support of the transfer belt unit 8 is released. Has been.

  When the transfer belt unit 8 is completely inserted into the image forming apparatus, the power receiving connector 240 is inserted and connected to the power supply connector 241 to complete the connection (see FIG. 1).

  In this state, when the transfer belt unit 8 is moved upward and pressed against positioning, the state shown in FIG. 13 or FIG. 14 is obtained, that is, the state shown in FIG. 14 in the multicolor mode and the state in the single color mode. 13 states. In the multicolor mode, the power supply connector 241 moves upward together with the transfer belt unit 8 as indicated by an arrow in FIG.

  In the monochromatic mode, a margin is provided for the size of the slide hole 241a with respect to the thickness of the slide shaft 242 so that the power supply connector 241 can be inclined according to the inclination of the transfer belt unit 8 at the raised position. Therefore, normal communication and power supply can always be performed.

  This eliminates the need for a serviceman to attach and detach the connector by hand, and the connector is automatically attached and detached simply by opening and closing the side cover 35, so that no connection mistakes occur and the workability such as maintenance is improved. Work time is shortened and maintenance costs can be reduced.

  Needless to say, when the side cover 35 is opened, the power supply to the transfer belt unit 8 is disconnected for safety.

  In this embodiment, the transfer carrier is described as the transfer belt 7. However, the same effect can be obtained not only with the belt-like transfer belt but also with a transfer carrier using a drum-like transfer drum or the like. .

  In addition, the conveyance belt apparatus having only a function of conveying a recording member or the like without being limited to the transfer carrier has substantially the same structure as the transfer belt, and thus can be implemented as the same configuration of the transfer belt unit 8 described above. Needless to say.

  In the above-described embodiment, the description has been given using the image forming apparatus of the type in which the sheet is carried on the transfer belt 7 and directly transferred to the sheet. However, the present invention is not limited to this. The present invention is also applicable to an intermediate transfer type image forming apparatus that once transfers an image formed on a photosensitive drum to a transfer belt, superimposes the image on the intermediate transfer belt, and then performs batch transfer onto the conveyed sheet. .

  FIG. 24 is a diagram illustrating a configuration of an intermediate transfer type image forming apparatus. In FIG. 24, the same components as those in the image forming apparatus shown in FIG.

  In this image forming apparatus, the transfer belt 7 of the transfer belt unit 8 is used as an intermediate transfer belt 7a, and a secondary transfer member (secondary transfer roller) provided to face a roller member 71a corresponding to the drive roller 71. 90.

  After the toner image formed on each photosensitive drum (image carrier) 3 is once transferred to the intermediate transfer belt 7a, the toner image is conveyed toward a place where the intermediate transfer belt 7a and the secondary transfer member 90 are in pressure contact with each other. The image is retransferred to the sheet by a secondary transfer member (transfer roller) 90.

FIG. 3 is a diagram illustrating a configuration of a main part of the image forming apparatus when the separation belt mechanism according to an embodiment of the present invention is applied to the transfer belt unit and the transfer belt unit is in a free state. It is a figure which shows attachment and detachment of a transfer belt unit. It is a figure which shows the structure of a rail member and a slide part. 1 is a diagram illustrating a configuration of a main part of an image forming apparatus. It is a perspective view shown about the structure of the transfer belt unit corresponding to a unit lift arm. 4A and 4B are diagrams illustrating a positional relationship between the photosensitive drum and the transfer belt unit. FIG. 5A illustrates a case where the transfer belt unit is in a free state, FIG. 5B illustrates a case where the image forming mode is a multicolor mode, FIG. 6C is a diagram illustrating a case where the image forming mode is a single color mode. FIG. 4 is a diagram illustrating a configuration of a photosensitive drum, a transfer belt unit, and a separation / contact control unit viewed from the rear side in a multicolor mode. FIG. 3 is a diagram illustrating a configuration of a photosensitive drum, a transfer belt unit, and a separation / contact control unit viewed from the rear side in a single color mode. FIG. 3 is a diagram illustrating the configuration of a separation / contact control unit from the front side of the image forming apparatus. It is a perspective view shown about the structure of a separation / contact control part. It is a figure which shows the state which the convex part and stop member of the process unit left | separated. It is a figure which shows the state which the convex part and stop member of the process unit engaged. FIG. 6 is a diagram illustrating a state in which one of the support shafts of the transfer belt unit is supported by a rail member in the monochrome mode. FIG. 6 is a diagram illustrating a state in which one of the support shafts of the transfer belt unit is supported by a rail member in the multicolor mode. 2 is a perspective view illustrating a configuration of an exterior of the image forming apparatus. FIG. It is a perspective view which shows the structure of a transfer belt unit. The structure of the housing in the two support units connected is shown, (a) is a perspective view when viewed from below, and (b) is a perspective view when viewed from above. The structure of the housing to which the roller was attached is shown, (a) is a perspective view when viewed from below, and (b) is a perspective view when viewed from above. (A) is a perspective view which shows the structure of the connected housing, (b) is a figure which expands and shows the area | region shown by B in (a), (c) is C in (a). It is a figure which expands and shows the area | region shown by. It is a figure which shows the structure of the transfer belt unit at the time of bending a support unit in a substantially V shape. It is a figure which shows a structure when two housings become a substantially V shape. It is a figure which compares the height of a transfer roller, and is a figure which shows the cross section of the principal part of two transfer rollers shown to Fig.18 (a). 1 is a diagram illustrating a configuration of a copying machine including an image forming apparatus and a paper feeding device. FIG. 3 is a diagram illustrating a configuration of a main part of an intermediate transfer type image forming apparatus.

Explanation of symbols

3a to 3d photosensitive drum (image carrier, carrier)
6 Transfer roller (transfer member)
7 Transfer belt (transfer carrier, contact member)
8 Transfer belt unit (transfer carrier device, contact member)
18 Slide part (biasing member)
35 Side cover (part of exterior)
38 Separation / contact control unit (biasing member)
78a Support shaft 78b Support shaft 86 Connecting portion 201 Rail member (support member, positioning member)
202 Rail groove (guide groove)
202a recess (positioning means)
202b Positioning hole (positioning means)
202c Recess (Position restricting means)
203a Convex part (position regulating means)
205 Front frame (frame member, frame)
206 Rear frame (frame member, frame)
211 Unit lift arm 231 Stop member (blocking member)
233 Stop member lift arm

Claims (11)

An image carrier on which an image is formed based on image data, and a transfer carrier device that has a transfer carrier that can be separated from and contacted with the image carrier and transfers the image by contacting the image carrier. In the provided image forming apparatus,
The image forming apparatus, wherein the transfer carrier device is separated from the image carrier by an operation of opening a part of the exterior of the image forming device. An image carrier on which an image is formed based on image data, and a transfer carrier device that has a transfer carrier that can be separated from and contacted with the image carrier and transfers the image by contacting the image carrier. In the provided image forming apparatus,
In the image forming apparatus, the support for the image forming apparatus main body is released by an operation in which a part of the exterior of the image forming apparatus is opened. The part of the exterior is an exterior parallel to the axis of the roller member that rotatably supports the transfer carrier of the transfer carrier device among the exteriors of the image forming apparatus,
The image forming apparatus according to claim 1, wherein a part of the exterior is opened in a direction orthogonal to the axis of the roller member.   3. The transfer carrier device according to claim 1, wherein the transfer carrier device is detachable with respect to the image forming apparatus main body, and the detachment is performed when a part of the exterior is opened. Image forming apparatus. The frame member of the image forming apparatus main body includes a positioning member for positioning the transfer carrier device with respect to the image forming apparatus main body,
3. The image forming apparatus according to claim 1, wherein the positioning member includes a position restricting unit for restricting a displacement of the transfer carrier device in the positioning member. The frame member of the image forming apparatus main body includes a rail member that guides the transfer carrier device when the transfer carrier device is attached to and detached from the image forming apparatus main body.
The rail member includes a positioning means for positioning the transfer carrier device with respect to the image forming apparatus main body, and the transfer carrier on the rail member when a part of the exterior of the image forming apparatus is opened. The image forming apparatus according to claim 1, further comprising a position regulating unit configured to regulate a positional deviation of the body device.   The position restricting means is a concave portion that is disposed so as to face at least one of the positioning means and restricts a positional deviation of a shaft of a roller member that rotatably supports the transfer carrier. The image forming apparatus according to claim 6.   When the transfer carrier is in contact with the image carrier, it engages with an image carrier unit including the image carrier, while the transfer carrier is not in contact with the image carrier. The image forming apparatus according to claim 1, further comprising a blocking member that is disengaged from the image carrier unit and moves in conjunction with the opening / closing operation of the exterior. An image carrier on which an image is formed based on image data, and a transfer carrier device that has a transfer carrier that can be separated from and contacted with the image carrier and transfers the image by contacting the image carrier. In the provided image forming apparatus,
The transfer carrier device is attached to and detached from the image forming apparatus main body by moving the transfer carrier device in a direction perpendicular to the axis of a roller member that rotatably supports the transfer carrier. Forming equipment.   10. A plurality of image carriers are arranged in a direction perpendicular to the axis of a roller member that rotatably supports the transfer carrier. Image forming apparatus. A transfer carrier device having an image carrier on which an image is formed based on image data, and a transfer carrier that is separable from the image carrier and is applied with a voltage by a transfer member and transfers the image. A plurality of the image carriers in a direction perpendicular to the axis of a roller member that rotatably supports the transfer carrier, and the image is used by contacting all of the plurality of image carriers with the transfer carrier. In an image forming apparatus having a forming mode and an image forming mode in which any one of the plurality of image carriers is used in contact with the transfer carrier,
When an image forming mode using the specific image carrier is selected, a transfer member corresponding to an image carrier that is not used and excluding a transfer member located at least at the end is not attached to the transfer carrier. An image forming apparatus configured to be in a contact state.

Images