Image formation apparatus

Abstract

To facilitate attachment and detachment of an intermediate transfer unit.SOLUTION: An image formation apparatus comprises photoconductors 25Y, 25M, 25C, 25K that carry toner images, a transfer unit 100 that receives toner images from the photoconductors and carries the toner images, a secondary transfer roller 26 that transfers the toner images carried by the transfer unit 100 to a recording medium, a fixing device 32 that fixes the toner images onto the recording medium, and a conveyance guide 150 that is provided between the secondary transfer roller 26 and the fixing device 32 to guide the recording medium conveyed from the secondary transfer roller 26 toward the fixing device 32. The transfer unit 100 is attachable to and detachable from an apparatus body, and the conveyance guide 150 is retractable to a retracted position where it does not interfere with attachment and detachment of the transfer unit 100 during the attachment or detachment of the transfer unit 100.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus equipped with an image carrier that carries a toner image. [Background technology]

[0002] 2. Description of the Related Art Image forming apparatuses that form images using toner of multiple colors are known. For example, Japanese Patent No. 6358218 describes an image forming apparatus including an image carrier provided in a device body, an endless intermediate transfer belt onto which a toner image formed on the image carrier is transferred, a drive roller and a driven roller that rotatably suspend the intermediate transfer belt, an intermediate transfer unit that is insertable into and removable from the device body along the direction in which the intermediate transfer belt is suspended by the drive roller and the driven roller, a secondary transfer roller that is disposed downstream of the intermediate transfer unit in a direction in which the intermediate transfer unit is pulled out from the device body and that abuts against the outer surface of the intermediate transfer belt to form a nip portion with the intermediate transfer belt, and a fixing unit that is disposed above the intermediate transfer unit and fixes the toner image transferred from the intermediate transfer belt to a recording medium, and that is insertable into and removable from the device body in the same direction as the intermediate transfer unit, and

[0003] In the image forming apparatus described in Japanese Patent No. 6358218, when inserting or removing an intermediate transfer unit, the intermediate transfer unit must be moved upward to separate it from the image carrier, and then pulled out of the apparatus. Because an intrusion prevention member is provided between the intermediate transfer unit and the fixing unit, the intrusion prevention member interferes with the intermediate transfer unit or the fixing unit when inserting or removing the intermediate transfer unit. This requires removing the intrusion prevention member or the fixing unit before inserting or removing the intermediate transfer unit, which places a burden on the operator. Another problem is that operators may forget to install the intrusion prevention member after installing the intermediate transfer unit. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6358218 Summary of the Invention [Problem to be solved by the invention]

[0005] SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and one of the objects of the present invention is to provide an image forming apparatus in which the intermediate transfer unit can be easily attached and detached. [Means for solving the problem]

[0006] According to one aspect of the present invention, an image forming apparatus includes a photosensitive member that carries a toner image, an intermediate transfer unit that receives the toner image from the photosensitive member and carries the toner image, a transfer section that transfers the toner image carried by the intermediate transfer unit to a recording medium, a fixing section that fixes the toner image to the recording medium, and a transport guide that is provided between the transfer section and the fixing section and that guides the recording medium transported from the transfer section toward the fixing section, wherein the intermediate transfer unit is detachable from the apparatus main body, and the transport guide is retractable to a retracted position that does not interfere with the attachment and detachment of the intermediate transfer unit when the intermediate transfer unit is attached or detached. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a perspective view showing the appearance of an image forming apparatus according to an embodiment of the present invention; [Figure 2] FIG. 2 is a schematic cross-sectional view showing an example of the internal configuration of an image forming apparatus. [Figure 3] FIG. 2 is a perspective view of the image forming apparatus with the door open. [Figure 4] FIG. [Figure 5] FIG. [Figure 6] FIG. 6 is a first diagram showing a cross section taken along line AA in FIG. 5. [Figure 7] FIG. 6 is a second view showing a cross section taken along line AA in FIG. 5. [Figure 8] FIG. 6 is an enlarged view of a region R in FIG. 5. [Figure 9] FIG. [Figure 10] FIG. [Figure 11] FIG. 10 is a diagram showing a state in which the slider and the transport guide are connected. [Figure 12] 10A and 10B are diagrams illustrating an example of the relative positional relationship between a conveyance guide positioned at a guide position and a slider. [Figure 13] FIG. 10 is a perspective view showing the conveying guide and the slider positioned at the guide position. [Figure 14] 10A and 10B are diagrams illustrating an example of the relative positional relationship between a transport guide located at a retracted position and a slider. [Figure 15] FIG. 10 is a perspective view showing the transport guide and the slider positioned at the retracted position. [Figure 16] FIG. [Figure 17] FIG. 10 is a diagram showing a state in which the rotary lever and the transport guide are connected. [Figure 18] 10A and 10B are diagrams illustrating an example of the relative positional relationship between a conveyance guide located at a guide position and a rotary lever. [Figure 19] 10A and 10B are diagrams illustrating an example of the relative positional relationship between a transport guide located at a retracted position and a slider. DETAILED DESCRIPTION OF THE INVENTION

[0008] An image forming apparatus according to an embodiment of the present invention will now be described with reference to the drawings. In the following description, identical components are designated by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

[0009] First Embodiment Fig. 1 is a perspective view showing the appearance of an image forming apparatus according to the present embodiment. Referring to Fig. 1, image forming apparatus 1 includes an automatic document feeder 2, a document reading unit 3, an image forming unit 4, a paper feed unit 5, and an operation panel 6. Automatic document feeder 2 automatically transports multiple documents set on a document tray one by one to a document reading position of document reading unit 3, and ejects the documents, from which images formed on the documents are read by document reading unit 3, onto a document output tray.

[0010] The document reading unit 3 optically reads the document that has been transported to the document reading position by the automatic document feeder 2. The document reading unit 3 outputs image data obtained by optically reading the document to the image forming unit 4.

[0011] The paper feed unit 5 includes two paper feed cassettes 35, 35A for storing paper. The paper feed unit 5 transports paper stored in either of the two paper feed cassettes 35, 35A to the image forming unit 4. The image forming unit 4 forms an image using a well-known electrophotographic method, and forms an image on paper transported by the paper feed unit 5 based on image data, and discharges the paper with the image formed onto the paper output tray 7.

[0012] The operation panel 6 has a display device and an operation unit, and accepts operations input by a user. The image forming apparatus 1 operates in accordance with the operations input to the operation panel 6.

[0013] FIG. 2 is a schematic cross-sectional view showing an example of the internal configuration of an image forming apparatus. FIG. 2 shows a cross-section of the image forming apparatus as seen from the front. An X direction, a Y direction, and a Z direction are defined, which are orthogonal to each other. The X direction and the Y direction are parallel to a horizontal plane. In the following description, the X direction is parallel to the left and right of the image forming apparatus 1 and is also referred to as the left-right direction. The Y direction is parallel to the depth direction of the image forming apparatus 1 and is also referred to as the front-rear direction. The Z direction is parallel to the up-down direction of the image forming apparatus 1 and is also referred to as the up-down direction. In the image forming apparatus 1, the main scanning direction is parallel to the Y direction, and the sub-scanning direction is parallel to the X direction.

[0014] Referring to FIG. 2, the image forming section 4 includes image forming units 20Y, 20M, 20C, and 20K, a transfer unit 100, a secondary transfer roller 26, and a fixing device 32. The image forming units 20Y, 20M, 20C, and 20K correspond to yellow, magenta, cyan, and black, respectively. Here, "Y," "M," "C," and "K" represent yellow, magenta, cyan, and black, respectively. An image is formed by driving at least one of the image forming units 20Y, 20M, 20C, and 20K. A full-color image is formed by driving all of the image forming units 20Y, 20M, 20C, and 20K. Printing data for yellow, magenta, cyan, and black is input to the image forming units 20Y, 20M, 20C, and 20K, respectively. The image forming units 20Y, 20M, 20C, and 20K differ only in the color of the toner they handle, so here, the image forming unit 20Y for forming a yellow image will be described.

[0015] The image forming unit 20Y includes a charging roller 21Y, an exposure device 22Y, a developing device 23Y, a primary transfer roller 24Y, a photosensitive member 25Y serving as an image carrier, and a toner bottle 41Y. The toner bottle 41Y contains yellow toner. The toner bottle 41Y is rotated by a toner bottle motor as a driving source, and discharges developer to the outside. The toner discharged from the toner bottle 41Y is supplied to the developing device 23Y.

[0016] The photoconductor 25Y is a cylindrical drum that can rotate around an axis of rotational symmetry. Around the photoconductor 25Y, a charging roller 21Y, an exposure device 22Y, a developing device 23Y, and a primary transfer roller 24Y are arranged in this order along the direction of rotation of the photoconductor 25Y.

[0017] After the surface of the photoreceptor 25Y is charged by the charging roller 21Y, it is irradiated with laser light emitted by the exposure device 22Y. The exposure device 22Y exposes an image-corresponding portion of the surface of the photoreceptor 25Y to light to form an electrostatic latent image. This forms an electrostatic latent image on the photoreceptor 25Y. Next, the developer 23Y develops the electrostatic latent image formed on the photoreceptor 25Y with toner. Specifically, toner held by the developing roller of the developer 23Y is placed on the electrostatic latent image formed on the photoreceptor 25Y by the action of electric field force, thereby forming a toner image on the photoreceptor 25Y. The toner image formed on the photoreceptor 25Y is transferred onto the transfer belt 30, which is an image carrier, by the action of electric field force using the primary transfer roller 24Y.

[0018] The transfer unit 100 includes a transfer belt 30, a drive roller 33, and a driven roller 34. The transfer belt 30 is suspended between the drive roller 33 and the driven roller 34 to prevent slack. When the drive roller 33 rotates clockwise in the figure, the transfer belt 30 rotates clockwise at a predetermined speed. Accompanying the rotation of the transfer belt 30, the driven roller 34 rotates clockwise. This causes the image forming units 20Y, 20M, 20C, and 20K to transfer toner images onto the transfer belt 30 in this order. The timing at which each of the image forming units 20Y, 20M, 20C, and 20K transfers a toner image onto the transfer belt 30 is adjusted by detecting a reference mark on the transfer belt 30. As a result, yellow, magenta, cyan, and black toner images are superimposed on the transfer belt 30.

[0019] When forming a full-color image, the image forming apparatus 1 drives all of the image forming units 20Y, 20M, 20C, and 20K. As a result, yellow, magenta, cyan, and black toner images are superimposed on the transfer belt 30. When forming a monochrome image, the image forming apparatus 1 drives any one of the image forming units 20Y, 20M, 20C, and 20K. It is also possible to form an image using a combination of two or more of the image forming units 20Y, 20M, 20C, and 20K.

[0020] Paper of different sizes is set in paper feed cassettes 35 and 35A, respectively. The paper stored in paper feed cassettes 35 and 35A is supplied to a conveyance path by take-out rollers 36 and 36A attached to paper feed cassettes 35 and 35A, respectively, and sent to timing rollers 31 by paper feed roller 37.

[0021] Timing roller 31 transports the paper transported by paper feed roller 37 to the nip between transfer belt 30 and secondary transfer roller 26, which is a transfer member. Secondary transfer roller 26 generates an electric field at the nip. The toner image formed on transfer belt 30 is transferred to the paper transported by timing roller 31 by the action of the electric field force at this nip. The paper with the transferred toner image is transported to fixing device 32, where it is heated and pressurized. This melts the toner and fixes it to the paper. The paper is then ejected to paper output tray 7.

[0022] Fig. 3 is a perspective view of the image forming apparatus with the door open. Referring to Fig. 3, the housing 10 of the image forming apparatus 1 has a door 11 on the left side of the housing 10. The door 11 can be opened and closed. The housing 10 has a storage space that houses the image forming unit 4 and the paper feed unit 5. When the door 11 is in the open state, the storage space of the housing 10 is open to the outside. When the door 11 is in the closed state, the storage space of the housing 10 is not open to the outside. The inner surface of the door 11 on the storage space side forms one side of a transport path through which paper passes.

[0023] When the door 11 of the housing 10 is in an open state, the ends of the transfer unit 100 and the fixing device 32 on the negative side in the X direction are exposed. This allows the user to access the transfer unit 100. A transport guide 150 is disposed between the transfer unit 100 and the fixing device 32. The transport guide 150 is fixed to the transfer unit 100. The transfer unit 100 can be removed from the housing 10 by pulling it out in the negative X direction as indicated by the arrow in the figure.

[0024] FIG. 4 is a perspective view of the transfer unit. FIG. 5 is a plan view of the transfer unit. Note that the conveying guide 150 is not shown in FIG. 5. FIG. 6 is a first diagram showing a cross section taken along line AA in FIG. 5. Referring to FIGS. 4 to 6, the transfer unit 100 includes a front frame 101A and a rear frame 101B. The front frame 101A and the rear frame 101B face each other and are disposed at a predetermined distance in the Y direction. A drive roller 33 and a driven roller 34 are disposed between the front frame 101A and the rear frame 101B. The front frame 101A and the rear frame 101B each have bearings that support the rotation shafts of the drive roller 33 and the driven roller 34.

[0025] The front frame 101A has a first front guide pin 103A and a second front guide pin 105A that protrude in a direction parallel to the Y direction from the surface opposite to the surface facing the rear frame 101B. The first front guide pin 103A and the second front guide pin 105A are arranged at a predetermined interval in the X direction. The rear frame 101B has a first rear guide pin 103B and a second rear guide pin 105B that protrude in a direction parallel to the Y direction from the surface opposite to the surface facing the front frame 101A. The first rear guide pin 103B and the second rear guide pin 105B are arranged at a predetermined interval in the X direction.

[0026] The positioning plate 109 has a flat plate shape, and both ends thereof are fixed to the upper surface of the front frame 101A and the upper surface of the rear frame 101B, respectively. The positioning plate 109 is positioned above the transfer belt 30 at the end on the negative side in the X direction of each of the front frame 101A and the rear frame 101B.

[0027] A front handle 107A is provided at the end of the front frame 101A on the negative side in the X direction. A rear handle 107B is provided at the end of the rear frame 101B on the negative side in the X direction. The front handle 107A and the rear handle 107B are sized and shaped to be grippable by a user. A user can grip the front handle 107A and the rear handle 107B with both hands. This makes it easier for a user to attach the transfer unit 100 to the housing 10 or remove the transfer unit 100 from the housing 10. Specifically, the user can easily move the transfer unit 100 up and down, move the transfer unit 100 horizontally, and rotate the transfer unit 100 horizontally.

[0028] The transfer unit 100 is attached to or detached from the housing 10 by sliding it in a direction parallel to the X direction within the housing 10. As shown in Fig. 6, the transfer unit 100 is supported by and fixed to the housing 10 at both ends in the Y direction. The configuration in which the transfer unit 100 is supported and fixed to the housing 10 is the same at both ends in the Y direction, so the configuration will be described here using the front side of the transfer unit 100 as an example.

[0029] A first front guide 13A is fixed to the inside of the front wall of the housing 10. A second front guide 15A is fixed to the inside of the rear wall of the housing 10. Each of the first front guide 13A and the second front guide 15A is a plate extending in the X direction. The first front guide 13A extends in the Z direction and has a restriction surface 17A formed thereon that faces the positive side of the X direction.

[0030] When the transfer unit 100 is located at the receiving position, the first front guide pin 103A fixed to the front frame 101A is supported by the first front guide 13A, and the second front guide pin 105A fixed to the front frame 101A is supported by the second front guide 15A. Furthermore, while the first front guide pin 103A is supported by the first front guide 13A, its movement to the negative side in the X direction is restricted by the restriction surface 17A.

[0031] When the user attaches or detaches the transfer unit 100 to or from the housing 10, the first front guide pin 103A needs to be positioned above the regulating surface 17A. When the user attaches or detaches the transfer unit 100 to or from the housing 10, this includes when the transfer unit 100 is removed from the housing 10 and when the transfer unit 100 is attached to the housing 10.

[0032] Meanwhile, a transport guide 150 is fixed to the transfer unit 100. The transport guide 150 is located between the secondary transfer roller 26 and the fixing device 32. In this embodiment, the transport guide 150 is located between the transfer unit 100 and the fixing device 32. For this reason, when the relative positions of the transfer unit 100 and the transport guide 150 are in the positional relationship shown in FIG. 6, the transfer unit 100 cannot be moved upward without the transport guide 150 coming into contact with the fixing device 32. The position of the transport guide 150 when the relative positions of the transfer unit 100 and the transport guide 150 are in the positional relationship shown in FIG. 6 is referred to as the guide position.

[0033] In the image forming apparatus 1 of the present embodiment, when the transfer unit 100 is attached to or detached from the housing 10, the conveying guide 150 is retracted to a retracted position that does not interfere with the attachment or detachment of the transfer unit 100. The configuration for moving the conveying guide 150 from the guide position to the retracted position will be described in detail later.

[0034] Figure 7 is a second diagram showing the cross section taken along line AA in Figure 5. Figure 7 shows the transfer unit 100 in a state after the transport guide 150 has moved from the guide position to the retracted position. A space is secured between the transfer unit 100 and the fixing device 32. Here, the operation by the user to attach or detach the transfer unit 100 to or from the housing 10 in a state after the transport guide 150 has moved from the guide position to the retracted position will be described.

[0035] When the user attaches the transfer unit 100 to the housing 10, first, the user places the second front guide pin 105A of the transfer unit 100 on the second front guide 15A. In this state, when the user pushes the transfer unit 100 toward the positive side in the X direction, the second front guide pin 105A slides on the second front guide 15A. Next, the user places the first front guide pin 103A on the first front guide 13A with the first front guide pin 103A positioned on the first front guide 13A. At this stage, the vertical positions of the first front guide pin 103A and the opposing first rear guide pin 103B, and the second front guide pin 105A and the opposing second rear guide pin 105B of the transfer unit 100 are determined.

[0036] The first front guide 13A has a first portion on the negative side of the regulating surface 17A in the X direction and a second portion on the positive side, which are different in height. The first portion is located higher than the second portion. The height of the second portion is such that the distance between the transfer belt 30 of the transfer unit 100 and each of the photoconductors 25Y, 25M, 25C, and 25K is a predetermined distance. Therefore, when the first front guide pin 103A is located above the first portion, the distance between the transfer unit 100 and each of the photoconductors 25Y, 25M, 25C, and 25K is longer than the predetermined distance. Therefore, while the first front guide pin 103A slides on the first portion, the transfer belt 30 abuts against the photoconductors 25Y, 25M, 25C, and 25K, preventing damage to the photoconductors 25Y, 25M, 25C, and 25K and the transfer belt 30.

[0037] Furthermore, when the user pushes the transfer unit 100 toward the positive side in the X direction, the first front guide pin 103A moves further toward the positive side in the X direction than the regulating surface 17A. When the first front guide pin 103A moves further toward the positive side in the X direction than the regulating surface 17A, the height of the first front guide pin 103A is determined by the second portion of the first front guide 13A. This adjusts the distance between the transfer unit 100 and the photoconductors 25Y, 25M, 25C, and 25K to a predetermined distance.

[0038] An elastic member that biases the transfer unit 100 toward the negative side in the X direction is provided on the inner surface of the right wall of the housing 10. When the user releases the transfer unit 100 after the first front guide pin 103A has moved beyond the regulating surface 17A to the positive side in the X direction, the first front guide pin 103A abuts against the regulating surface 17A, and the transfer unit 100 is positioned at the receiving position. With the first front guide pin 103A positioned on the regulating surface 17A, the installation of the transfer unit 100 into the housing 10 is complete. In this state, the transfer belt 30 of the transfer unit 100 contacts the secondary transfer roller 26 diagonally below the secondary transfer roller 26 on the negative side in the X direction of the transfer unit 100, and the distance between the transfer belt 30 and the photoconductors 25Y, 25M, 25C, and 25K becomes a predetermined distance.

[0039] When the user removes the transfer unit 100 from the housing 10, the user first moves the transfer unit 100 upward to the separated position where the first front guide pin 103A is above the regulating surface 17A. Since the transfer unit 100 is biased in the negative X direction, the transfer unit 100 moves in the negative X direction. The positional relationship between the transfer unit 100 and the housing 10 at this stage is shown in FIG. 7.

[0040] Because the first front guide pin 103A does not abut against the regulating surface 17A, the transfer unit 100 can move in the negative X direction. When the user moves the transfer unit 100 in the negative X direction, the first front guide pin 103A slides on the first front guide 13A, and the second front guide pin 105A slides on the second front guide 15A. When the first front guide pin 103A is positioned above the first portion, the distance between the transfer unit 100 and the photoconductors 25Y, 25M, 25C, and 25K is longer than a predetermined distance. Therefore, while the first front guide pin 103A slides above the first portion, the transfer belt 30 abuts against the photoconductors 25Y, 25M, 25C, and 25K, preventing damage to the photoconductors 25Y, 25M, 25C, and 25K and the transfer belt 30.

[0041] Furthermore, when the user moves the transfer unit 100 to the negative side in the X direction, the first front guide pin 103A moves further to the negative side in the X direction than the first front guide 13A, and the second front guide pin 105A slides on the second front guide 15A. Thereafter, the user can remove the transfer unit 100 from the housing 10.

[0042] Next, a configuration for moving the conveying guide 150 between the guiding position and the retracted position will be described. FIG. 8 is an enlarged view of region R in FIG. 5. Referring to FIG. 8, the slider 110 is disposed between the rear handle 107B and the rear frame 101B. A hole penetrating the rear handle 107B in the X direction is formed, and the slider 110 passes through the hole and is disposed in the gap between the rear handle 107B and the rear frame 101B. The gap between the rear handle 107B and the rear frame 101B has a shape that extends in the X direction. Because the slider 110 is sandwiched between the rear handle 107B and the rear frame 101B, movement in the Y direction is restricted.

[0043] FIG. 9 is a perspective view of a slider. Referring to FIG. 9, slider 110 includes a pressed plate 111, a slide plate 112, a guide plate 115, a locking portion 117, and an engaging portion 119. Slide plate 112 has opposite surfaces and is a flat plate extending in the X direction. Each of the surfaces is perpendicular to the Y direction. Guide groove 113 is formed in slide plate 112. Guide groove 113 has a first groove and a second groove that are parallel to the X direction. The first groove and second groove partially overlap in the X direction and are formed in slide plate 112 at a predetermined interval in the Z direction.

[0044] The end of the sliding plate 112 on the negative side in the X direction is connected to the pressed plate 111. The pressed plate 111 perpendicularly intersects with both faces of the sliding plate 112. The end of the sliding plate 112 on the positive side in the X direction is connected to the guide plate 115. The pressed plate 111 has a pressed surface that is perpendicular to the X direction and faces the negative side in the X direction.

[0045] The end of the slide plate 112 on the positive side in the X direction is connected to a guide plate 115 and an engagement portion 119. The guide plate 115 has a guide surface 116 facing the negative side in the X direction. A locking portion 117 is fixed to the end of the guide plate 115 opposite the guide surface 116. The locking portion 117 has a cylindrical shape extending in the Y direction. The locking portion 117 protrudes further toward the negative side in the Y direction than the guide plate 115 in the Y direction. The engagement portion 119 is disposed adjacent to the negative side of the guide plate 115 in the X direction. The engagement portion 119 is a groove extending in the Y direction and has an engagement surface that connects to the lower end of the guide surface 116. The engagement surface has a curved shape that protrudes downward when cut along a plane perpendicular to the Y direction.

[0046] FIG. 10 is a perspective view of the transport guide. Referring to FIG. 10, the transport guide 150 has a sliding protrusion 151 at its end on the positive side in the Y direction. Similarly, the transport guide 150 has a sliding protrusion 151 at its end on the negative side in the Y direction. The two sliding protrusions 151 formed at both ends of the transport guide 150 in the Y direction are each cylindrical, and their rotational symmetry axes are parallel to the Y direction. The rotation axes of the two sliding protrusions 151 formed at both ends of the transport guide 150 in the Y direction are collinear. The sliding protrusion 151 at the end on the positive side in the Y direction of the transport guide 150 is journaled by the rear frame 101B. The sliding protrusion 151 at the end on the positive side in the Y direction of the transport guide 150 is journaled by the front frame 101A. Therefore, the transport guide 150 rotates around the rotation axis of the sliding protrusion 151 relative to the front frame 101A and the rear frame 101B.

[0047] The transport guide 150 has a vertical portion 150A and a horizontal portion 150B near the center between both ends in the Y direction. The vertical portion 150A and the horizontal portion 150B are flat plate-shaped extending in the Y direction and perpendicularly intersect each other. A cross section of the transport guide 150 taken near the center along a plane perpendicular to the Y direction is L-shaped. When the transport guide 150 is positioned at the guide position, the lower surface of the horizontal portion 150B abuts against the upper surface of the positioning plate 109. Therefore, when the horizontal portion 150B of the transport guide 150 abuts against the positioning plate 109, the rotation of the transport guide 150 is restricted, and the transport guide 150 is positioned at the guide position.

[0048] 11 is a diagram showing the state in which the slider and the conveying guide are connected. The locking portion 117 of the slider 110 and the sliding protrusion 151 of the conveying guide 150 are connected by a tension spring 123. One end of a compression spring 121 is connected to the surface of the pressed plate 111 of the slider 110 opposite to the pressed surface. The other end of the compression spring 121 is connected to the rear frame 101B.

[0049] FIG. 12 is a diagram illustrating an example of the relative positional relationship between the transport guide and the slider when the transport guide is positioned at the guide position. FIG. 13 is a perspective view illustrating the transport guide and the slider when the transport guide is positioned at the guide position. Referring to FIGS. 12 and 13, the rear frame 101B is provided with a first guide pin 108A and a second guide pin 108B on the surface opposite to the surface facing the front frame 101A. The first guide pin 108A and the second guide pin 108B are provided in a portion of the rear frame 101B that overlaps with the rear handle 107B. The first guide pin 108A and the second guide pin 108B are arranged on the rear frame 101B at a predetermined interval in the X direction. The first guide pin 108A and the second guide pin 108B protrude from the rear frame 101B in a direction parallel to the Y direction. The first rear guide pin 103B and the second rear guide pin 105B are arranged at a predetermined interval in the X direction.

[0050] The slider 110 is attached to the rear frame 101B with the first guide pin 108A and the second guide pin 108B passing through the guide groove 113. Therefore, the slider 110 is restricted in its movement in the Z direction and its rotational movement in a plane perpendicular to the Y direction by the first guide pin 108A and the second guide pin 108B, but is movable in the X direction. The movement of the slider 110 in the X direction is limited within the range of the X-direction length of the guide groove 113. The position where the slider 110 has moved furthest in the positive X direction is referred to as the operating position, and the position where the slider 110 has moved furthest in the negative X direction is referred to as the attachment / detachment position. The figure shows the slider 110 in the operating position.

[0051] In FIG. 12, as shown by the white arrow, the force of the pressed plate 111 is directed in the positive X direction. In this state, the slider 110 moves to the positive side in the X direction and is positioned at the attachment / detachment position. In this case, the compression spring 121 disposed between the pressed plate 111 and the rear frame 101B is compressed.

[0052] 3, a pressing portion 19 is provided on the inner surface of door 11 of housing 10 at a position corresponding to slider 110. Referring to FIGS. 3 and 12, when door 11 is closed, pressing portion 19 comes into contact with pressed plate 111 of slider 110, and pressing portion 19 presses pressed plate 111 toward the positive side in the X direction. This causes slider 110 to move toward the positive side in the X direction and to assume the attachment / detachment position. Therefore, when door 11 of housing 10 is closed, slider 110 moves toward the positive side in the X direction and assumes the operating position.

[0053] The locking portion 117 of the slider 110 is connected to the sliding protrusion 151 of the transport guide 150 via a tension spring 123. The transport guide 150 has two rotation shafts 153 at both ends, which are supported by the front frame 101A and the rear frame 101B, respectively. Therefore, the sliding protrusion 151 receives a force in the positive X direction and rotates around the rotation shaft 153, thereby positioning the transport guide 150 at the guiding position. The guiding position is a state in which the horizontal portion 150B of the transport guide 150 abuts against the positioning plate 109. In this state, it is preferable that the distance between the sliding protrusion 151 and the locking portion 117 be longer than the length of the tension spring 123. The tension spring 123 is extended by a predetermined length and applies a force that rotates the transport guide 150 in the clockwise direction, as indicated by the thick black arrow in FIG. 12, thereby reliably positioning the transport guide 150.

[0054] Fig. 14 is a diagram showing an example of the relative positional relationship between the transport guide and the slider when they are in the retracted position. Fig. 15 is a perspective view showing the transport guide and the slider when they are in the retracted position. Referring to Figs. 14 and 15, as indicated by the outline arrow, the pressed plate 111 receives a force from the compression spring 121 in the negative X-direction, causing the slider 110 to move in the negative X-direction. The elastic force of the compression spring 121 is greater than the elastic force of the tension spring 123.

[0055] 3 and 12, when door 11 is opened, pressing portion 19 moves away from pressed plate 111 of slider 110. As a result, pressed plate 111 no longer receives force from pressing portion 19, and slider 110 moves in the positive X direction to the attachment / detachment position due to the elastic force of compression spring 121. Therefore, when door 11 of housing 10 is opened, slider 110 moves in the positive X direction and is positioned in the attachment / detachment position.

[0056] During a first movement period in which the slider 110 moves from the operating position to the attachment / detachment position, the transport guide 150 moves from the guide position to the retracted position. During the first movement period, the guide plate 115 of the slider 110 pushes the sliding protrusion 151 toward the negative side of the X direction. This causes the transport guide 150 to rotate counterclockwise around the rotation axis 153, as indicated by the thick black arrow in the figure. During the first movement period, the sliding protrusion 151 slides along a guide surface 116 formed on the sliding protrusion 151. The relative position between the sliding protrusion 151 and the slider 110 changes during this movement period as the sliding protrusion 151 moves from above to below along the guide surface 116 of the guide plate 115 and abuts against an engagement portion 119 connected to the guide surface 116. When the sliding protrusion 151 abuts against the engagement portion 119, the transport guide 150 stops rotating, and the slider 110 stops moving. When the slider 110 is in the attachment / detachment position, the sliding protrusion 151 abuts against the engagement portion 119, and the transport guide 150 is in the retracted position.

[0057] 12 and 14, during a second movement period in which the slider 110 moves from the attachment / detachment position to the operating position, the transport guide 150 moves from the retracted position to the guide position. During the second movement period, the slider 110 moves in the positive X direction, and the locking portion 117 moves in the positive X direction. When the distance between the locking portion 117 and the sliding protrusion 151 becomes longer than the length of the tension spring 123, the sliding protrusion 151 receives a force in a direction toward the negative X direction. This causes the transport guide 150 to rotate around the rotation axis 153 in the clockwise direction as indicated by the thick black arrow in FIG. 12. When the horizontal portion 150B of the transport guide 150 abuts against the positioning plate 109, the transport guide 150 stops rotating and is positioned at the guide position.

[0058] In the present embodiment, while the sliding protrusion 151 moves between the guide position and the retracted position, the sliding protrusion 151 is positioned above the rotation shaft 153. In other words, the sliding protrusion 151 moves between the guide position and the retracted position within a range in which the sliding protrusion 151 is positioned above the rotation shaft 153.

[0059] <Second embodiment> In the image forming apparatus 1 in the first embodiment, the transfer unit 100 has a slider 110. In the image forming apparatus 1 in the second embodiment, the transfer unit 100 has a rotary lever 130 instead of the slider 110. Other configurations are the same as those of the image forming apparatus 1 in the first embodiment, so here, the image forming apparatus 1 in the second embodiment will be mainly described with reference to the differences from the image forming apparatus 1 in the first embodiment.

[0060] FIG. 16 is a perspective view of a rotary lever. Referring to FIG. 16, rotary lever 130 has rotary bearing 131 and a first end and a second end sandwiching rotary bearing 131. A contact portion 135 is provided at the first end, and a locking portion 133 is provided at the second end. Rotary lever 130 has a flat plate shape with both sides perpendicular to the Y direction. Rotary bearing 131 is an opening that penetrates the flat plate in the Y direction. Locking portion 133 is an opening that penetrates the flat plate in the Y direction. A contact portion 135 is provided on the opposite side of the rotary bearing 131 from the end where locking portion 133 is formed. A contact portion 135 has an abutment surface facing the negative side in the Z direction. Abutting portion 135 is formed by bending a flat plate at a right angle.

[0061] 17 is a diagram showing the state in which the rotary lever and the conveying guide are connected. The locking portion 133 of the rotary lever 130 and the sliding protrusion 151 of the conveying guide 150 are connected by a tension spring 123.

[0062] Figure 18 is a diagram showing an example of the relative positional relationship between the conveyance guide located at the guide position and the rotary lever. Referring to Figure 18, a lever rotation shaft 106 is provided on the rear frame 101B. The lever rotation shaft 106 protrudes from the rear frame 101B in a direction parallel to the Y direction. The lever rotation shaft 106 is provided above the first rear guide pin 103B.

[0063] The lever rotation shaft 106 is inserted into the rotation bearing 131 of the rotation lever 130, whereby the rotation lever 130 is attached to the rear frame 101B. The rotation lever 130 is rotatable around the lever rotation shaft 106 while attached to the rear frame 101B. The distance between the rotation shaft of the rotation bearing 131 of the rotation lever 130 and the abutment portion 135 is longer than the length of the restriction surface 17B in the Z direction.

[0064] The locking portion 133 of the rotating lever 130 is connected to the sliding protrusion 151 of the transport guide 150 via the tension spring 123. The transport guide 150 has a rotation shaft 153 which is supported by the rear frame 101B. When the transport guide 150 is located at the guiding position, its center of gravity is located on the negative side in the X direction relative to the lever rotation shaft 106.

[0065] When the user rotates the rotating lever 130 clockwise, the sliding protrusion 151 receives a force in the positive X direction, rotates around the rotation axis 153, and is positioned at the guide position. The guide position is a state in which the horizontal portion 150B of the transport guide 150 abuts against the positioning plate 109. In this state, it is preferable that the distance between the sliding protrusion 151 and the locking portion 117 is longer than the length of the tension spring 123. The tension spring 123 is extended by a predetermined length, and a force is applied to rotate the transport guide 150 in the clockwise direction as indicated by the thick black arrow in FIG. 18, thereby ensuring that the transport guide 150 is positioned reliably. The position of the rotating lever 130 shown in FIG. 18 is referred to as the operating position.

[0066] Fig. 19 is a diagram showing an example of the relative positional relationship between the transport guide and the slider when the transport guide is in the retracted position. Referring to Fig. 19, when the rotary lever 130 rotates from the operating position in a direction in which the abutment portion 135 faces the first rear guide 13B, the rotary lever 130 rotates to the detachment position shown in Fig. 19. The center of gravity of the transport guide 150 is located on the negative side of the lever rotation shaft 106 in the X direction. Therefore, during a first movement period in which the rotary lever 130 moves from the operating position to the detachment position, the transport guide 150 rotates around the rotation shaft 153 in the counterclockwise direction as indicated by the thick black arrow in Fig. 17.

[0067] The locking portion 133 of the rotating lever 130 and the sliding protrusion 151 of the conveying guide 150 are connected by the tension spring 123. Therefore, when the rotating lever 130 stops at the attachment / detachment position, the conveying guide 150 also stops.

[0068] Furthermore, because the contact portion 135 of the rotary lever 130 contacts the first rear guide 13B, the point of contact between the contact portion 135 and the first rear guide 13B serves as a fulcrum, and the rotary bearing 131 serves as a point of action. As a result, the rotary bearing 131 rotates around the point of contact between the contact portion 135 and the first rear guide 13B. Because the point of contact between the contact portion 135 and the first rear guide 13B is fixed, the rotary bearing 131 moves in a direction away from the first rear guide 13B. As a result, the first rear guide 13B moves above the restricting surface 17B.

[0069] An elastic member that biases the transfer unit 100 toward the negative side in the X direction is provided on the inner surface of the right wall of the housing 10. The first rear guide 13B moves to the negative side in the X direction beyond the regulating surface 17B. The positional relationship between the transfer unit 100 and the housing 10 at this stage is shown in FIG. 19.

[0070] 18 and 19, during a second movement period in which the rotating lever 130 moves from the attachment / detachment position to the operating position, the transport guide 150 moves from the retracted position to the guide position. During the second movement period, the rotating lever 130 rotates clockwise, causing the locking portion 117 to move toward the positive side of the X direction. When the distance between the locking portion 117 and the sliding protrusion 151 becomes longer than the length of the tension spring 123, the sliding protrusion 151 receives a force toward the negative side of the X direction. This causes the transport guide 150 to rotate clockwise around the rotation axis 153, as indicated by the thick black arrow in FIG. 18. When the horizontal portion 150B of the transport guide 150 abuts against the positioning plate 109, the transport guide 150 stops rotating and is positioned at the guide position.

[0071] In the second embodiment, while the sliding protrusion 151 moves between the guide position and the retracted position, the sliding protrusion 151 is positioned above the rotation shaft 153. In other words, the sliding protrusion 151 moves between the guide position and the retracted position within a range in which the sliding protrusion 151 is positioned above the rotation shaft 153.

[0072] <Other embodiments> In the image forming apparatus 1 according to the first embodiment, the center of gravity of the conveying guide 150 in the XY plane may be arranged to be on the negative side in the X direction relative to the rotation axis 153. In this case, the conveying guide 150 rotates due to gravity, and therefore the guide surface 116 does not need to be provided.

[0073] As described above, the image forming apparatus 1 in this embodiment is provided with a transport guide 150 that is provided between the secondary transfer roller 26 and the fixing device 32 and that guides paper transported from the secondary transfer roller 26 toward the fixing device 32. When attaching the transfer unit 100 to the housing 10 or when removing the transfer unit 100 from the housing 10, the transport guide 150 can be retracted to a retracted position that does not interfere with the attachment or removal of the transfer unit 100. This eliminates the need to remove the transport guide 150 before attaching or removing the intermediate transfer unit 100, making it easy to attach or remove the transfer unit 100.

[0074] Furthermore, the conveying guide 150 retreats from the guiding position to the retreat position before the transfer unit 100 moves from the receiving position to the separating position. Therefore, after the conveying guide 150 retreats to the retreat position, the transfer unit 100 can be moved from the receiving position to the separating position, making it possible to attach and detach the transfer unit 100.

[0075] The image forming apparatus 1 also includes a first front guide 13A having a regulating surface 17A extending in the Z direction. The transfer unit 100 includes a first front guide pin 103A that positions the transfer unit 100. The first front guide pin 103A abuts against the regulating surface 17A when the transfer unit 100 is below the fixing device 32 and above the photoconductors 25Y, 25M, 25C, and 25K, maintaining a predetermined distance from the photoconductors 25Y, 25M, 25C, and 25K. This positions the transfer unit 100 in the X direction. Therefore, the regulating surface 17A determines the horizontal position of the transfer unit 100. Furthermore, when the first front guide pin 103A moves above the regulating surface 17A, horizontal movement is no longer regulated, simplifying the process of attaching and detaching the transfer unit 100.

[0076] Furthermore, the conveying guide 150 has a rotation shaft 153, and moves between the guiding position and the retracted position by rotating around the rotation shaft 153. This makes it possible to eliminate the need to remove the conveying guide 150 with a simple configuration.

[0077] Furthermore, the rotation shaft 153 is supported by the transfer unit 100. This improves the accuracy of positioning the conveyance guide at the guide position.

[0078] The transport guide 150 also has a sliding protrusion 151 at one end parallel to the rotation shaft 153, extending in a direction square to the rotation shaft 153, and the sliding protrusion 151 is connected to the locking portion 117 by the tension spring 123. Therefore, as the slider 110 moves toward the positive X-direction, the sliding protrusion 151 receives a force in the positive X-direction from the tension spring 123, allowing the transport guide 150 to move from the retracted position to the guide position. The slider 110 also has a guide surface 116 facing the negative X-direction and abutting against the sliding protrusion 151. As the slider moves toward the negative X-direction, the guide surface 116 moves toward the negative X-direction, and the guide surface 116 pushes the sliding protrusion 151 toward the negative X-direction. Therefore, the transport guide 150 can be moved from the guide position to the retracted position.

[0079] The slider 110 further includes a compression spring 121 that biases the slider 110 toward the negative side in the X direction. The slider 110 has a pressed plate 111 at its end on the negative side in the X direction, and the door 11 of the housing 10 has a pressing portion 19 on its inner surface facing the internal space that abuts against the pressed plate 111 in the closed state. As the door 11 changes from the closed state to the open state, the pressed plate 111 no longer abuts against the pressing portion 19, and the slider 110 moves toward the negative side in the X direction due to the action of the compression spring 121. As the door 11 changes from the open state to the closed state, the pressing portion 19 presses the pressed plate 111 toward the positive side in the X direction, and the slider 110 moves toward the positive side in the X direction. Therefore, the slider 110 can be moved in the X direction as the door 11 of the housing 10 is opened or closed.

[0080] Furthermore, the slider 110 is provided on the transfer unit 100. Therefore, the slider 110 can be accurately positioned with respect to the transfer unit 100, and the slider 110 can be accurately positioned with respect to the conveyance guide 150.

[0081] Furthermore, the transport guide 150 rotates within a rotation range in which its center of gravity does not overlap the rotation shaft 153 in the up-down direction on a plane perpendicular to the rotation shaft 153. The transport guide 150 has a sliding protrusion 151 extending in a direction parallel to the rotation shaft 153 at one end parallel to the rotation shaft 153. The transport guide 150 has a center of gravity located away from the rotation shaft 153 on the negative X-direction side on a plane perpendicular to the rotation shaft 153 (XY plane), and the slider 110 has a locking portion 117 connected to the sliding protrusion 151. Therefore, as the slider 110 moves toward the positive X-direction side, the sliding protrusion 151 moves together with the locking portion 117. This allows the transport guide 150 to move from the retracted position to the guiding position. As the slider 110 moves toward the negative X-direction side, the sliding protrusion 151 moves together with the locking portion 117. Since the center of gravity of the transport guide 150 is located away from the rotation shaft 153 on the negative side in the X direction, the sliding protrusion 151 moves on the negative side in the X direction. This allows the transport guide 150 to move from the guiding position to the retracted position.

[0082] Furthermore, in the image forming apparatus 1 according to the second embodiment, the distance between the contact portion 135 of the rotary lever 130 and the rotary bearing 131 is longer than the distance between the rotary bearing 131 and the first rear guide pin 103B when the transfer unit 100 is attached to the housing 10. Therefore, when the rotary lever 130 is in the attachment / detachment position, the first rear guide pin 103B can be positioned above the restriction surface 17B. Furthermore, when the rotary lever 130 is in the operating position, the first rear guide pin 103B can be brought into contact with the restriction surface 17B. This makes it easier to attach and detach the transfer unit 100.

[0083] <Summary of implementation form> (Item 1) A photoreceptor that carries a toner image; an intermediate transfer unit that receives the toner image from the photoreceptor and carries the toner image; a transfer section that transfers the toner image carried by the intermediate transfer unit onto a recording medium; a fixing unit that fixes the toner image onto the recording medium; a conveyance guide provided between the transfer unit and the fixing unit, the conveyance guide guiding the recording medium conveyed from the transfer unit toward the fixing unit, the intermediate transfer unit is detachable from the main body of the apparatus; The image forming apparatus, wherein the transport guide is retractable to a retracted position where it does not interfere with the attachment or detachment of the intermediate transfer unit when the intermediate transfer unit is attached or detached.

[0084] According to this aspect, the transport guide provided between the transfer section that transfers the toner image carried by the intermediate transfer unit onto the recording medium and the fixing section can be retracted to a retracted position that does not interfere with the installation and removal of the intermediate transfer unit when the intermediate transfer unit is installed or removed. This eliminates the need to remove the transport guide before installing or removing the intermediate transfer unit, making it possible to provide an image forming apparatus in which the intermediate transfer unit can be easily installed and removed.

[0085] (Item 2) The intermediate transfer unit is moved from a receiving position where it receives the toner image from the photosensitive member to a separated position away from the photosensitive member, and then is detached from the device main body; Item 2. The image forming apparatus according to item 1, wherein the transport guide retracts from a guide position for guiding the recording medium to the retracted position before the intermediate transfer unit moves from the receiving position to the separated position.

[0086] According to this aspect, the transport guide retracts from the guide position to the retracted position before the intermediate transfer unit moves from the receiving position to the separating position. Therefore, after the transport guide has retracted to the retracted position, the intermediate transfer unit can be moved from the receiving position to the separating position, making it possible to attach and detach the intermediate transfer unit.

[0087] (Item 3) The positioning unit further includes a regulating surface extending in the vertical direction, 3. The image forming apparatus according to item 2, wherein the intermediate transfer unit has a convex portion that contacts the regulating surface when the intermediate transfer unit is positioned in a vertical direction.

[0088] According to this aspect, the intermediate transfer unit, which is located below the fixing unit and above the photosensitive member and in contact with the photosensitive member, has its convex portion abutting against the regulating surface when its vertical position is determined. Therefore, the horizontal position of the intermediate transfer unit is determined by the positioning unit. Furthermore, since the horizontal movement of the convex portion is no longer restricted when the convex portion is moved above the positioning unit, the work of attaching and detaching the intermediate transfer unit can be simplified.

[0089] (Item 4) The image forming apparatus according to item 2 or 3, wherein the transport guide has a rotation shaft and moves between the guide position and the retracted position by rotating around the rotation shaft.

[0090] According to this aspect, the transport guide moves between the guiding position and the retracted position by rotating about the rotation axis, which makes it possible to eliminate the need for removing the transport guide with a simple configuration.

[0091] (Item 5) The image forming apparatus according to Item 3, wherein the rotation shaft is supported by the intermediate transfer unit.

[0092] Therefore, the accuracy of positioning the transport guide at the guide position can be improved.

[0093] (Item 6) The image forming apparatus according to item 4 or 5, wherein the conveying guide rotates within a rotation range in which the center of gravity of the conveying guide does not overlap the rotation shaft in the up-down direction on a plane perpendicular to the rotation shaft.

[0094] In this aspect, the center of gravity of the transport guide does not overlap with the rotation axis in the vertical direction, so that the transport guide can be rotated by applying a force in one direction to the transport guide.

[0095] (Item 7) The conveying guide has a sliding protrusion extending in a direction parallel to the rotation axis, 7. The image forming apparatus according to any one of items 4 to 6, further comprising: a slider that is directly or indirectly connected to the slide protrusion and is attached so as to be movable in one direction within a plane that intersects with the rotation shaft.

[0096] According to this aspect, the transport guide can be rotated in accordance with the movement of the slider in one direction. By moving the slider in a first direction, the sliding protrusion can be moved in the first direction, thereby moving the transport guide from the retracted position to the guide position. Furthermore, by moving the slider in a second direction opposite to the first direction, the sliding protrusion can be moved in the second direction, thereby moving the transport guide from the guide position to the retracted position.

[0097] (Item 8) The slider includes an engagement portion connected to the slide protrusion via a first elastic member; 8. The image forming apparatus according to item 7, further comprising: a guide surface disposed between the sliding protrusion and the engagement portion in the one direction and facing a second direction opposite to a first direction toward the engagement portion.

[0098] According to this aspect, as the slider moves in the first direction, the engaging portion moves in the first direction. Because the sliding protrusion is connected to the engaging portion via the first elastic member, as the engaging portion moves in the first direction, the sliding protrusion moves in the first direction. This allows the transport guide to be moved from the retracted position to the guide position. Furthermore, as the slider moves in the second direction, the guide surface moves in the second direction, so the guide surface facing the second direction pushes the sliding protrusion in the second direction. Accordingly, the sliding protrusion moves in the second direction. This allows the transport guide to be moved from the guide position to the retracted position.

[0099] (Item 9) The image forming apparatus according to item 7 or 8, wherein the slider is provided in the intermediate transfer unit.

[0100] According to this aspect, the slider is provided on the intermediate transfer unit, so that the slider can be accurately positioned with respect to the intermediate transfer unit and the conveyance guide.

[0101] (Item 10) A housing having an internal space in which the photosensitive member, the intermediate transfer unit, the transfer unit, the fixing unit, and the conveyance guide are accommodated; a second elastic member that biases the slider in a first direction, the slider has a pressed portion at an end in the first direction, the housing has a door that can be opened and closed between an open state in which at least a portion of the internal space is opened to the outside and a closed state in which the internal space is not opened to the outside, 10. The image forming apparatus according to any one of items 7 to 9, wherein the door has a pressing member on a surface facing the internal space, the pressing member being in contact with the pressed portion in the closed state.

[0102] According to this aspect, as the door changes from the closed state to the open state, the pressed portion is no longer in contact with the pressing member, so the slider moves in the first direction. Also, as the door changes from the open state to the closed state, the pressing member presses the pressed portion in the second direction, so the slider moves in the second direction. Therefore, the slider can be moved in one direction as the door opens and closes.

[0103] (Item 11) A positioning portion having a regulating surface extending in the vertical direction; a rotating lever attached to the intermediate transfer unit so as to be rotatable around a lever rotating shaft protruding from a side surface of the intermediate transfer unit, the rotating lever having a first end and a second end sandwiching the lever rotating shaft therebetween; the intermediate transfer unit has a convex portion that contacts the regulating surface when the position of the intermediate transfer unit in the up-down direction is determined, The protrusion is disposed below the lever rotation shaft, the distance between the first end and the lever rotation shaft is longer than the length of the restriction surface in the up-down direction; 7. The image forming apparatus according to any one of items 4 to 6, wherein the second end is connected to the transport guide.

[0104] According to this aspect, the convex portion is positioned below the lever rotation shaft, so that the convex portion can be brought into contact with the regulating surface to position the intermediate transfer unit. Furthermore, because the distance between the first end and the lever rotation shaft is longer than the vertical length of the regulating surface, the convex portion can be moved above the positioning portion. This makes the intermediate transfer unit detachable. Furthermore, the second end is connected to the transport guide. Therefore, by moving the rotating lever in a first rotation direction, the transport guide can be rotated in the first rotation direction, so that the transport guide can be moved from the retracted position to the guide position. Furthermore, by moving the rotating lever in a second rotation direction opposite to the first rotation direction, the transport guide can be rotated in the second rotation direction, so that the transport guide can be moved from the guide position to the retracted position.

[0105] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0106] 1 image forming device, 2 automatic document feeder, 3 document reading unit, 4 image forming unit, 5 paper feed unit, 6 operation panel, 7 paper output tray, 10 housing, 11 door, 13A first front guide, 13B first rear guide, 15A second front guide, 17A regulating surface, 17B regulating surface, 19 pressing unit, 20Y, 20M, 20C, 20K image forming unit, 21Y charging roller, 22Y exposure device, 23Y developing unit, 24Y primary transfer roller, 25Y, 25M, 25C, 25K photosensitive body, 26 secondary transfer roller, 30 transfer belt, 31 timing roller, 32 fixing device, 33 drive roller, 34 driven roller, 35, 35A paper feed cassette, 36, 36A take-out roller, 37 paper feed roller, 41Y Toner bottle, 100 transfer unit, 101A front frame, 101B rear frame, 103A first front guide pin, 103B first rear guide pin, 105A second front guide pin, 105B second rear guide pin, 106 lever rotation shaft, 107A front handle, 107B rear handle, 108A first guide pin, 108B second guide pin, 109 positioning plate, 110 slider, 111 pressed plate, 112 slide plate, 113 guide groove, 115 guide plate, 116 guide surface, 117 engaging portion, 119 engaging portion, 121 compression spring, 123 tension spring, 130 rotating lever, 131 rotating bearing, 133 engaging portion, 135 abutting portion, 150 conveying guide, 150A vertical portion, 150B Horizontal part, 151 sliding projection, 153 rotating shaft.

Claims

1. a photoreceptor carrying a toner image; an intermediate transfer unit that receives the toner image from the photoreceptor and carries the toner image; a transfer section that transfers the toner image carried by the intermediate transfer unit onto a recording medium; a fixing unit that fixes the toner image onto the recording medium; a conveyance guide provided between the transfer unit and the fixing unit, the conveyance guide guiding the recording medium conveyed from the transfer unit toward the fixing unit, the intermediate transfer unit is detachable from the main body of the apparatus; The image forming apparatus, wherein the transport guide is retractable to a retracted position where it does not interfere with the attachment or detachment of the intermediate transfer unit when the intermediate transfer unit is attached or detached.

2. the intermediate transfer unit is moved from a receiving position where it receives the toner image from the photosensitive member to a separated position away from the photosensitive member, and then is detached from the apparatus main body; 2. The image forming apparatus according to claim 1, wherein the transport guide retracts from a guide position for guiding the recording medium to the retracted position before the intermediate transfer unit moves from the receiving position to the separated position.

3. a positioning portion having a restriction surface extending in the vertical direction, 3. The image forming apparatus according to claim 2, wherein the intermediate transfer unit has a convex portion that comes into contact with the regulating surface when the position of the intermediate transfer unit in the up-down direction is determined.

4. 3. The image forming apparatus according to claim 2, wherein the transport guide has a rotation shaft, and moves between the guiding position and the retracted position by rotating around the rotation shaft.

5. 5. The image forming apparatus according to claim 4, wherein the rotation shaft is supported by the intermediate transfer unit.

6. 5. The image forming apparatus according to claim 4, wherein the conveying guide rotates within a rotation range in which a center of gravity of the conveying guide does not overlap with the rotation shaft in the up-down direction on a plane perpendicular to the rotation shaft.

7. The conveying guide has a sliding protrusion extending in a direction square to the rotation shaft, 7. The image forming apparatus according to claim 4, further comprising a slider connected directly or indirectly to said sliding protrusion and attached so as to be movable in one direction within a plane intersecting said rotation shaft.

8. the slider includes an engaging portion connected to the sliding protrusion via a first elastic member; 8. The image forming apparatus according to claim 7, further comprising: a guide surface disposed between the sliding protrusion and the engaging portion in the one direction, the guide surface facing a second direction opposite to the first direction toward the engaging portion.

9. The image forming apparatus according to claim 7 , wherein the slider is provided in the intermediate transfer unit.

10. a housing having an internal space in which the photosensitive member, the intermediate transfer unit, the transfer section, the fixing section, and the conveyance guide are housed; a second elastic member that biases the slider in a first direction parallel to the one direction, the slider has a pressed portion at an end in the first direction, the housing has a door that can be opened and closed between an open state in which at least a portion of the internal space is opened to the outside and a closed state in which the internal space is not opened to the outside, The image forming apparatus according to claim 7 , wherein the door has a pressing member on a surface facing the internal space, the pressing member being in contact with the pressed portion in the closed state.

11. a positioning portion having a restriction surface extending in the vertical direction; a rotating lever attached to the intermediate transfer unit so as to be rotatable around a lever rotating shaft protruding from a side surface of the intermediate transfer unit, the rotating lever having a first end and a second end sandwiching the lever rotating shaft therebetween, the intermediate transfer unit has a convex portion that contacts the regulating surface when the position of the intermediate transfer unit in the up-down direction is determined, The protrusion is disposed below the lever rotation shaft, a distance between the first end and the lever rotation shaft is longer than a vertical length of the restriction surface; 7. The image forming apparatus according to claim 4, wherein the second end is connected to the transport guide.

Images