JP5929615B2 - Image forming apparatus - Google Patents

Description

The present invention is a copying machine, a printer, relates to an electrophotographic image forming apparatus such as a facsimile, in particular, it relates to an image forming apparatus to facilitate the attachment and detachment of the transfer belt unit.

  Conventionally, a toner image is formed on an image carrier using an electrophotographic method using toner, the toner image is transferred directly or indirectly to a sheet via an intermediate transfer member, and the transferred toner image is transferred by a fixing device. 2. Description of the Related Art Image forming apparatuses that fix images on paper and form images are known.

  Such an image forming apparatus includes, for example, a plurality of internal devices such as a transfer belt unit, an image forming unit, and a fixing unit in a detachable manner. During maintenance work of these internal devices, the internal device is removed from the mounting portion of the image forming apparatus main body, removed, repaired or replaced with a new one, and remounted on the mounting portion.

  In such attachment / detachment of the internal device, for example, it is stored on the surface of the unit when inserted into the device main body, appears in a position where it can be easily held when pulled out from the device main body, and interference with the device main body accompanying the insertion and withdrawal operations of the unit also occurs. Detachable units with no gripping parts are known.

  However, this attachment / detachment method is limited to a configuration in which the units are attached / detached in the vertical direction with respect to the attachment portion. Some image forming apparatuses have a system that is removed from the mounting part in the horizontal direction, such as an intermediate transfer belt unit that performs primary transfer by the secondary transfer system, and is replaced with a new one for maintenance or replacement. Technology is not applicable.

  On the other hand, an arm jig that urges the transfer belt (secondary transfer belt) unit in the separation direction with respect to the removal direction of the intermediate transfer (primary transfer) unit is arranged, and the front surface of the apparatus body housing is opened and closed. There has been proposed a mechanism that enables the intermediate transfer unit to be removed by providing a protrusion on the inside of the apparatus door and connecting the protrusion to and away from the arm jig in conjunction with opening and closing of the apparatus door. (For example, refer to Patent Document 1).

JP 2004-258092 A

  However, the technique disclosed in Patent Document 1 has a complicated configuration in which the secondary transfer unit is a transfer belt system, and further, the transfer belt unit of the secondary transfer unit is separated from and connected to the intermediate transfer unit of the primary transfer unit. In addition, a dedicated protrusion is provided on the apparatus door, and an urging member interlocking with the protrusion and an arm jig having a complicated structure are provided exclusively for the apparatus door.

  In an image forming apparatus having a large number of components and units, a dedicated cam device or interlocking mechanism with a complicated configuration such as an arm jig is not only used to increase the number of components but also increase the cost of the components. There remains a problem to be solved that man-hours increase and manufacturing costs also increase.

SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus in which a transfer belt unit can be easily attached and detached with a simple mechanism.

To solve the above problem, an image forming apparatus of the present invention, a transfer belt unit to which the toner image on the photosensitive drum to a transfer belt that circularly moves passed around a plurality of rollers is primarily transferred, and the transfer belt When the transfer belt unit is attached or detached, a secondary transfer roller for secondary transfer of the toner image primarily transferred to the transfer belt to the print medium is sandwiched between and the transfer belt unit. Of the opening / closing member, an opening / closing knob for locking or unlocking the opening / closing member, and the transfer belt and the secondary transfer roller, the secondary transfer roller is interlocked with the unlocking operation of the opening / closing knob. by moving a predetermined distance Te, and a linkage mechanism for separating the secondary transfer roller and the transfer belt, the interlocking mechanism, the secondary transfer roller An urging mechanism that applies a predetermined urging force to the transfer belt, and a support mechanism that receives the urging force instead of the transfer belt when the secondary transfer roller is separated from the transfer belt. and said that you are.

According to the present invention, it is possible to provide an image forming apparatus that can easily attach and detach the transfer belt unit with a simple mechanism.

1 is a cross-sectional view showing an internal configuration of a full-color image forming apparatus (printer, apparatus main body) according to Embodiment 1 of the present invention. 1 is an external perspective view of a printer according to Embodiment 1. FIG. 4 is a diagram specifically illustrating a unit lock cover disposed on the front surface when the transfer belt unit and four image forming units are mounted in the apparatus main body in the printer according to Embodiment 1. FIG. (a), (b), and (c) are the configuration and operation of an interlocking mechanism that engages with the secondary transfer roller unit of the printer according to the first embodiment and moves the secondary transfer roller to and away from the transfer belt unit. It is a front view for demonstrating. It is the perspective view which looked at FIG.4 (c) from the top.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description, printing and printing are used synonymously.

  Further, in the following description, the opening / closing member includes, for example, a unit lock cover 47, the opening / closing member opening / closing knob includes, for example, a lock cover opening / closing knob 50, and the interlocking mechanism includes, for example, the interlocking shaft 58, abutment. It consists of a plate 59 and the like.

  FIG. 1 is an external perspective view of a full-color image forming apparatus (hereinafter simply referred to as a printer or an apparatus main body) according to Embodiment 1 of the present invention.

  A printer 1 shown in FIG. 1 is an electrophotographic secondary transfer tandem color image forming apparatus, and includes an image forming unit 2, a transfer belt unit 3, a toner supply unit 4, a paper feeding unit 5, and a belt type fixing device. It comprises a unit 6 and a transport unit 7 for duplex printing.

  The image forming unit 2 transfers the toner image onto the lower running portion surface 8a of the transfer belt 8 by a so-called back transfer method, along the lower running portion surface 8a of the transfer belt 8, from the upstream side to the downstream side in the sheet conveying direction. Up to (from right to left in the figure), four image forming units 9 (9k, 9c, 9m, 9y) are arranged in a multistage manner.

  The image forming unit 2 is held by a frame of the printer 1 main body so as to be movable up and down from a printing execution position shown in FIG. 1 to a maintenance position below it. Of the four image forming units 9, three image forming units 9y, 9m, and 9c on the upstream side (the left side in the figure) are subtractive mixed primary colors yellow (Y), magenta (M), cyan ( A monocolor image is formed with the color toner of C).

  The image forming unit 9k forms a monochrome image using black (K) toner mainly used for characters and dark portions of images. Each of the image forming units 9 has the same configuration except for the color of the toner for developing the image. Accordingly, the configuration of the image forming unit 9y for yellow (Y) toner will be described below as an example.

  The image forming unit 9 includes a photosensitive drum 10 at the top. The photosensitive drum 10 has a peripheral surface made of, for example, an organic photoconductive material. A cleaner 11, a charging roller 12, an optical writing head 13, and a developing roller 15 of the developing device 14 are disposed in contact with or surrounding the periphery of the photosensitive drum 10.

  The developing device 14 includes a unit housing 16 that covers the outside, a partition wall 17 provided inside, a developing roller 15, a first stirring and conveying screw 18, and a second stirring and conveying screw 19. Although not specifically shown, the first and second agitating and conveying screws 18 and 19 include a screw shaft and a fin that is integrally formed with the screw shaft and rotates.

  The developing unit 14 includes a toner supply container 20 (20y, 20m, 20c, and 20k) of the toner supply unit 4, and yellow (Y) and magenta (M) as indicated by Y, M, C, and K in FIG. ), Cyan (C), or black (K) toner is supplied.

  The transfer belt unit 3 has an endless transfer belt 8 that extends in the shape of a flat loop in the left-right direction in the figure at approximately the center of the main unit, and the transfer belt 8 is stretched over the transfer belt 8. A driving roller 21 and a driven roller 22 are provided to circulate and move counterclockwise as indicated by an arrow a in the figure.

  Although not particularly shown, a belt position control mechanism is disposed inside the flat loop shape of the transfer belt 8. A primary transfer roller 23 is integrally incorporated in the belt position control mechanism. The primary transfer roller 23 is pressed against the photosensitive drum 10 via the transfer belt 8 and directly transfers (primary transfer) the toner image to the lower running portion surface 8a of the transfer belt 8 that circulates downward.

  The transfer belt 8 conveys the toner image to the paper secondary transfer unit 24 for further transfer (secondary transfer) to the paper. The secondary transfer unit 24 includes a transfer auxiliary roller 25 disposed on the downstream side (upward in the drawing) adjacent to the drive roller 21, and a secondary transfer roller 26 that is in pressure contact with the transfer auxiliary roller 25 via the transfer belt 8. And is formed.

  A belt cleaner 27 is disposed on the transfer belt 8. The belt cleaner 27 includes a cleaning blade 28 that contacts the surface of the transfer belt 8 that is stretched around the driven roller 22. A waste toner collection container 29 is detachably disposed adjacent to the belt cleaner 27 from the left to the bottom.

  The belt cleaner 27 scrapes off and removes the waste toner remaining on the surface of the transfer belt 8 by the cleaning blade 28, and sends the waste toner to the waste toner collection container 29 by a conveyance screw (not shown).

  The toner supply unit 4 includes four toner supply containers 20 (20y, 20m, 20c, and 20k) that are detachably disposed above the upper running unit of the transfer belt 8. As described above, the four toner supply containers 20 contain yellow (Y), magenta (M), cyan (C), and black (K) toners.

  These four toner replenishing containers 20 are hidden behind the opposite side of the transfer belt unit 3 in FIG. 1 but are not visible, but each corresponding image forming unit 9 via a toner supply path following the toner supply port of the mounting portion. The developing device 14 is connected.

  Although not particularly illustrated, the toner supply unit 4 is held on the frame of the main body of the printer 1 through a mounting unit so as to be movable up and down from a printing execution position shown in FIG. 1 to a maintenance position above it.

  The paper feed unit 5 includes two paper feed cassettes 30 (30a, 30b) arranged in two upper and lower stages. A paper take-out roller 31, a feed roller 32, a separating roller 33, and a standby conveyance roller pair 34 are disposed in the vicinity of the paper feed opening (right side in the figure) of the two paper feed cassettes 30, respectively.

  In the paper conveyance direction (vertical upward direction in the drawing) of the standby conveyance roller pair 34, the above-described secondary transfer portion 24 to the paper by the transfer belt 8, the transfer auxiliary roller 25, and the secondary transfer roller 26 is formed. On the forefront of the transfer belt unit 3 and the four image forming units 9, a unit lock cover 47, which is not shown in FIG.

  A belt-type heat fixing unit 6 is disposed on the downstream side (upper side in the drawing) of the secondary transfer unit 24, and the sheet after fixing is belt-type heat fixing unit further downstream of the belt-type heat fixing unit 6. A pair of unloading rollers 36 that unloads the sheet 6 and a pair of discharge rollers 38 that discharge the unloaded sheets to a sheet discharge tray 37 formed on the upper surface of the apparatus are disposed.

  The conveyance unit 7 for double-sided printing also serves as an opening / closing member whose outer surface (right outer surface in the drawing) opens or shields the inside of the printer 1 from the side surface to the outside.

  The duplex printing transport unit 7 has a return start path 39a that branches rightward in the figure from immediately before the paper discharge roller pair 38, a return intermediate path 39b that bends downward, and a left lateral direction opposite to the above. Thus, a return path 39 including a return end path 39c for finally inverting the return sheet is provided.

  In the middle of the return path 39, five pairs of return rollers 41 (41a, 41b, 41c, 41d, 41e) are arranged. The exit of the return termination path 39c joins a conveyance path to the standby conveyance roller pair 34 corresponding to the sheet feeding cassette 30b below the sheet feeding section 5.

  FIG. 2 is an external perspective view of the printer 1. As shown in FIG. 2, the printer 1 includes a front door 42 on the front side. Below the front door 42, the two paper feed cassettes 30a and 30b shown in FIG.

  In addition, the printer 1 includes an opening / closing member 45 having a handle 44 at the upper part on the right side surface. 1 is integrated with the opening / closing member 45. As shown in FIG. An operation panel unit 46 having a display unit and an input operation unit is disposed on the upper right side of the printer 1. Further, on the left side of the operation panel 46, a paper discharge tray 37 shown in FIG.

  As shown in FIG. 1, the printer 1 does not directly transfer a toner image onto a sheet. Instead, the printer 1 conveys a sheet conveyed vertically to a secondary transfer unit by a pair of standby conveying rollers 34 via a transfer belt 8. The toner image is transferred, and the sheet is further conveyed in the vertical direction to fix the transferred toner image on the sheet.

  Therefore, it is possible to cope with the maintenance process for recovering the trouble such as a paper jam occurring in the paper transport path by simply opening the right opening / closing member 45 shown in FIG. In other words, problems such as paper jams do not occur in the arrangement section of the kits.

  The operation of attaching and detaching consumables such as kits such as the transfer belt unit 3 and the image forming unit 9 concentrated on the left side of FIG. 1 is performed by opening the front door 42 shown in FIG. 2 and further the unit lock cover 47 shown in FIG. And the kits are configured to be replaced in the longitudinal direction (front door direction), that is, in the horizontal direction.

  3 shows the unit lock shown in FIG. 1 arranged on the front surface of the transfer belt unit 3 and the four image forming units 9m, 9c, 9y, 9k when they are mounted in the apparatus main body 1. FIG. It is a figure which shows the cover 47 concretely. The unit lock cover 47 opens and closes to the front side of the apparatus body 1 with the hinge 48 at the lower part as a fulcrum.

  Although not particularly shown, the unit lock cover 47 is provided with a lock mechanism for positioning the unit lock cover 47 on the apparatus main body 1. Therefore, when the unit lock cover 47 is locked to the apparatus main body 1, the transfer belt unit 3 is automatically positioned and fixed to the apparatus main body 1.

  In addition, a right end cover (not shown) is disposed adjacent to the right side of the unit lock cover 47. A secondary transfer roller unit (described later) that holds the secondary transfer roller 26 is integrally attached to the right end cover. The secondary transfer roller 26 is always positioned with respect to the transfer belt unit 3.

  A lock cover opening / closing knob 50 is disposed near the right end of the unit lock cover 47. The lock cover opening / closing knob 50 includes a circular main body rotation unit 51 and a squeeze 52 attached to the front surface of the main body rotation unit 51.

  The lock cover opening / closing knob 50 is rotatably attached to a cover lock position shown in FIG. 3 and a cover lock release position rotated 90 degrees counterclockwise as indicated by an arrow b.

  The lock cover opening / closing knob 50 is rotated to the cover lock position to prohibit the opening / closing of the unit lock cover 47, thereby positioning the transfer belt unit 3 and the four image forming units 9 in the apparatus main body 1 as described above. Removal from the apparatus main body 1 is prohibited by the unit lock cover 47.

  In this example, the inside of the lock cover opening / closing knob 50, that is, the inside of the unit lock cover 47 is formed in a cavity, although not particularly shown. Further, a plate-like body is disposed in a radial direction from one place of the shaft of the lock cover opening / closing knob 50 to the inner peripheral surface of the main body rotating portion 51.

  This plate-like body is formed corresponding to a position where the lock cover opening / closing knob 50 is in contact with the right side surface of the separation cam lever (not shown) when the lock cover opening / closing knob 50 is in the cover lock position as shown in FIG. The function of moving the transfer belt 8 to and away from the photosensitive drum 10 is provided.

  When a user or maintenance worker takes out the transfer belt unit 3 from the apparatus main body 1 in order to perform maintenance or inspection of the transfer belt unit 3, first, the front door 42 shown in FIG. 2 is opened. Next, to unlock the unit lock cover 47 shown in FIGS. 1 and 3, the lock cover opening / closing knob 50 is twisted 90 degrees counterclockwise.

  As a result, the lock of the unit lock cover 47 is released and the unit lock cover 47 can be opened, and the separation cam lever is rotated 90 degrees counterclockwise from the vertical position in conjunction with the lock cover opening / closing knob 50. The transfer belt unit 3 is separated from the photosensitive drum 10 by operating the belt position control mechanism.

  In the unit lock cover 47, the lock cover opening / closing knob 50 is further provided with another interlocking mechanism according to the present invention. This interlocking mechanism has a function of engaging with the secondary transfer roller unit to bring the secondary transfer roller 26 into and out of contact with the transfer belt unit 3.

  4 (a), 4 (b), and 4 (c) illustrate the configuration and operation of an interlocking mechanism that engages with the secondary transfer roller unit and separates the secondary transfer roller 26 from the transfer belt unit 3. It is a front view for demonstrating. 4A, 4B, and 4C, the same components as those shown in FIGS. 1 and 3 are denoted by the same reference numerals as those in FIGS.

  FIG. 5 is a perspective view of FIG. 4C as viewed from above. Hereinafter, the configuration of the interlocking mechanism of this example will be described first with reference to FIGS. 4 (a), (b), (c) and FIG. In the secondary transfer roller 26 shown in FIG. 1, both ends of the rotation shaft 53 are held by the secondary transfer roller unit 54.

  The secondary transfer roller unit 54 is always urged in the direction of the transfer belt unit 3 by the urging member 55 shown in FIGS. 4A, 4B, and 4C (not shown in FIG. 5). When no external force is applied to the secondary transfer roller unit 54, the secondary transfer roller 26 held by the secondary transfer roller unit 54 always transfers the auxiliary transfer roller 25 via the transfer belt 8 as shown in FIG. Is in pressure contact.

  FIG. 4A shows the state at this time, that is, the state where the secondary transfer roller 26 is engaged with the transfer belt unit 3. In FIG. 4A, since the secondary transfer roller 26 is engaged with the transfer belt unit 3, only the rotation shaft 53 is visible together with the bearing.

  In FIG. 4A, the roller body of the secondary transfer roller 26 appears hidden behind the frame of the transfer belt unit 3 that holds the bearings of the rotation shaft 56 of the auxiliary transfer roller 25 and the rotation shaft 57 of the drive roller 21. Absent. In FIGS. 4B, 4C and 5, the secondary transfer roller 26 is visible because the engagement between the secondary transfer roller 26 and the transfer belt unit 3 is released.

  FIG. 4B shows a state in which the lock cover opening / closing knob 50 is rotated 90 degrees counterclockwise as indicated by the arrow b from the state of FIG. As described above, since the lock of the unit lock cover 47 is released in the state of FIG. 4B, the unit lock cover 47 can be opened forward as shown in FIG. 4C.

  Also, as described above, the photosensitive drum 10 is separated from the transfer belt 8 of the transfer belt unit 3 in conjunction with the unlocking of the unit lock cover 47. In addition to this, in this example, as shown in FIG. 4 (c) (see also FIGS. 4 (a), (b) and FIG. 5), the interlocking shaft passes through the hinge 48 serving as the opening / closing fulcrum of the unit lock cover 47. 58 is provided.

  The interlocking shaft 58 engages with a plate-like body provided with the left end extending from the shaft of the lock cover opening / closing knob 50 provided in the cavity of the unit lock cover 47 described in FIG. It is configured to be possible. FIG. 4A shows a state in which the engagement is released, and FIGS. 4B, 4C, and 5 show a state in which the engagement is established.

  As shown in FIGS. 4 (a), (b), (c) and FIG. 5, the right end of the interlocking shaft 58 extends forward from the front end of the secondary transfer roller unit 54. It always abuts against the abutting surface 59-1 of the abutting plate 59 provided.

  When the lock cover opening / closing knob 50 is rotated 90 degrees counterclockwise as shown in FIG. 4B from the state in which the unit lock cover 47 shown in FIG. The interlocking shaft 58 engaged with the plate-like body of the knob 50 moves to the right in conjunction with the rotation of the lock cover opening / closing knob 50, presses the abutting surface 59-1 of the abutting plate 59, and the urging member 55 The secondary transfer roller unit 54 is moved rightward against the urging force.

  As a result, as shown in FIG. 4B, the engagement between the secondary transfer roller 26 and the transfer auxiliary roller 25 via the transfer belt 8 is released. Since the lock of the unit lock cover 47 is released, the unit lock cover 47 can be opened forward as shown in FIGS.

  Here, not only the engagement between the secondary transfer roller 26 and the transfer auxiliary roller 25 via the transfer belt 8 is released, but as described above, the lock cover opening / closing knob 50 is originally formed of the unit lock cover 47. A function of releasing the lock and separating the photosensitive drum 10 from the transfer belt unit 3 is provided.

  Thus, with the unit lock cover 47 opened to the front, the user or maintenance worker not only engages the photosensitive drum 10 of the image forming unit 9 and the transfer belt unit 3 but also the secondary transfer roller 26. The transfer belt unit 3 can be immediately removed from the apparatus main body 1 without paying attention to the engagement state between the transfer belt unit 3 and the transfer belt unit 3.

  As described above, according to this embodiment, when the unit lock cover 47 is opened, the lock of the lock cover opening / closing knob 50 that releases the lock of the unit lock cover 47 and releases the engaged state of the photosensitive drum 10 and the transfer belt unit 3 is opened. The engagement between the secondary transfer roller 26 and the transfer belt unit 3 is also released with a simple configuration that uses an interlocking mechanism that interlocks with the rotation of the roller and simply adds an interlocking shaft that interlocks with the interlocking mechanism and an abutment portion. be able to.

  The plurality of lock mechanisms are unlocked by a single operation of the lock cover opening / closing knob 50 by the interlock mechanism, so that the transfer belt (secondary transfer belt) unit can be maintained, inspected, replaced, etc. Can be easily performed without error without causing damage due to interference such as sliding contact between the belt and the secondary transfer roller.

  In FIG. 5, the secondary transfer roller unit 54 is controlled by a mechanism (not shown), for example, front and rear by guide rails, and moves in parallel to the transfer belt unit 3, that is, by the same distance in the front and rear.

  When the front end of the rotation shaft 53 of the secondary transfer roller 26 is turned as a fulcrum and the front is rotated in the separating direction, the distance of the separation is different between the front and the rear, but the entire roller circumferential surface is separated from the transfer belt unit 3. There is no change in. In this case, if a universal joint is disposed between the rotation shaft 53 of the secondary transfer roller 26 and the bearing, the rotation shaft 53 is not subjected to distortion due to rotation.

  In the present embodiment, the back transfer type image forming apparatus that transfers the toner image to be primarily transferred onto the lower running surface of the transfer belt has been described. However, the present invention is not limited to this, and the image is transferred to the upper running surface of the transfer belt. Needless to say, the present invention can also be applied to an image forming apparatus of the above type.

Although several embodiments of the present invention have been described, the present invention is included in the invention described in the claims and the equivalents thereof. Hereinafter, the invention described in the scope of claims of the present application will be appended.
[Appendix 1]

The device body;
A photosensitive drum that is detachably provided on the apparatus body and carries a developed toner image and rotates;
An intermediate transfer belt provided with an intermediate transfer belt that is circulated and moved over a plurality of rollers so as to be able to contact with and separate from the photosensitive drum and primary transfer the toner image on the photosensitive drum, and is detachably disposed on the apparatus main body. Unit,
A secondary transfer roller that holds a sheet in cooperation with the intermediate transfer belt unit and secondarily transfers a toner image on the intermediate transfer belt to the sheet so as to be in contact with and away from the intermediate transfer belt. Unit,
An opening / closing member provided in the apparatus main body and opened and closed when the photosensitive drum is attached to and detached from the apparatus main body;
An opening / closing member opening / closing knob for locking or unlocking the opening / closing member with respect to the apparatus main body;
The intermediate transfer belt engages with the opening / closing member opening / closing knob and the secondary transfer roller unit, and interlocks with the unlocking operation of the opening / closing member opening / closing knob via the secondary transfer roller unit. An interlocking mechanism for moving to a retracted position away from
An image forming apparatus comprising:
[Appendix 2]

The interlocking mechanism engages with the secondary transfer roller unit to return the secondary transfer roller from the retracted position to a position in contact with the intermediate transfer belt in conjunction with the locking operation of the opening / closing member opening / closing knob. The image forming apparatus according to supplementary note 1, wherein the image forming apparatus is released.
[Appendix 3]

There are a plurality of the photosensitive drums, and the plurality of photosensitive drums are arranged side by side in a multi-stage manner along the transfer surface of the intermediate transfer belt from the upstream side to the downstream side in the sheet conveying direction so as to form a full color image. The image forming apparatus according to Supplementary Note 1, wherein
[Appendix 4]

The image forming apparatus according to claim 1, wherein the intermediate transfer belt transfers the toner image onto a surface of a lower traveling portion that is circulated and moved.
[Appendix 5]

  2. The image forming apparatus according to claim 1, wherein the intermediate transfer belt transfers the toner image onto the surface of the upper traveling portion that is circulated.

  The present invention can be used in an image forming apparatus that can easily attach and detach a transfer belt unit in a horizontal direction with a simple mechanism.

1 Full-color image forming device (printer, device body)
DESCRIPTION OF SYMBOLS 2 Image formation part 3 Transfer belt unit 4 Toner supply part 5 Paper feed part 6 Belt type fixing unit 7 Conveyance unit for double-sided printing 8 Transfer belt 8a Lower travel part surface 9 (9m, 9c, 9y, 9k) Image formation unit 10 Photosensitive Body drum 11 Cleaner 12 Charging roller 13 Optical writing head 14 Developer 15 Developing roller 16 Unit housing 17 Bulkhead 18 First agitating and conveying screw 19 Second agitating and conveying screw 20 (20y, 20m, 20c, 20k) Toner replenishment Container 21 Drive roller 22 Driven roller 23 (23y, 23m, 23c, 23k) Primary transfer roller 24 Secondary transfer unit 25 Transfer auxiliary roller 26 Secondary transfer roller 27 Belt cleaner 28 Cleaning blade 29 Waste toner collection container 30 (30a, 30b) ) Paper cassette 31 Paper removal Roller 32 Feed roller 33 Rolling roller 34 Standby transport roller pair 36 Unloading roller pair 37 Paper discharge tray 38 Paper discharge roller pair 39 Return path 39a Return start path 39b Return intermediate path 39c Return end path 41 (41a, 41b, 41c, 41d) 41e) Return roller pair 42 Front door 43, 44 Handle 45 Opening / closing member 46 Operation panel 47 Unit lock cover 48 Hinge 50 Lock cover open / close knob 51 Main body rotating part 52 Stagnation 53 Rotating shaft of secondary transfer roller 54 Secondary transfer Roller unit 55 Biasing member 56 Rotating shaft of auxiliary transfer roller 57 Rotating shaft of driving roller

Claims (4)

A transfer belt unit to which the toner image on the photosensitive drum to a transfer belt that circularly moves passed around a plurality of rollers is primarily transferred,
A secondary transfer roller for secondarily transferring the toner image primarily transferred to the transfer belt to the print medium by sandwiching the print medium with the transfer belt;
An opening and closing member that is opened and closed when the transfer belt unit is attached and detached ;
An opening / closing knob for locking or unlocking the opening / closing member ;
By moving the secondary transfer roller of the transfer belt and the secondary transfer roller by a predetermined distance in conjunction with the unlocking operation of the opening / closing knob , the transfer belt and the secondary transfer roller are moved. An interlocking mechanism for separating
With
The interlock mechanism includes an urging mechanism that applies a predetermined urging force to the transfer belt via the secondary transfer roller, and the transfer belt instead of the transfer belt when the secondary transfer roller is separated from the transfer belt. An image forming apparatus comprising: a support mechanism that receives an urging force . The image forming apparatus according to claim 1, wherein the opening / closing knob is configured to show a locked state when turned in a horizontal direction and to show an unlocked state when turned in a vertical direction. apparatus. The image forming apparatus according to claim 1, wherein the transfer belt unit is configured to be detachable in a horizontal direction . 4. The image forming apparatus according to claim 1, further comprising a second interlocking mechanism for separating the transfer belt unit from the photosensitive drum in conjunction with an unlocking operation of the opening / closing knob. apparatus.