JP5821681B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus in which a transfer belt unit can be easily replaced.

  Conventionally, an image forming apparatus that forms a toner image on an image carrier using an electrophotographic method using toner, transfers the toner image onto a sheet, and fixes the transferred toner image on the sheet with a fixing device. It has been known.

  In the above transfer, for example, in the transfer device of the image forming apparatus, the primary transfer position for transferring the developed image from the image carrier to the transfer belt is firmly held by a highly convenient mechanism and the image forming apparatus. Has been proposed. (For example, refer to Patent Document 1.)

  By the way, such an image forming apparatus includes 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 housing, 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 housing, and appears in a position where it can be easily held when pulled out from the device housing. There have been proposed a detachable unit having a grip portion that does not cause any interference and an image forming apparatus having the same. (For example, see Patent Document 2.)

JP 2010-277066 A JP 2011-191459 A

  However, since many internal devices are heavy, when removing the internal device from the mounting portion, the internal device must be unlocked before removing it. Then, there is a possibility that the internal device may be damaged due to abnormal engagement such as catching with surrounding members.

  Regarding the unlocking of the device when removing the internal device from the mounting part, the unlocking of the door of the device housing, the unlocking of the protective cover member of the internal device, the unlocking that regulates the operation of the internal device, etc. It is necessary to release the lock.

  The work of sequentially releasing such various locks is troublesome, and even if you are careful, you forget to release it and try to remove the internal device from the mounting part. In many cases, the internal device is damaged due to an abnormal engagement.

  However, regarding the internal device of the image forming apparatus, no mechanism has been presented that can simplify such various lock releases.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus in which a plurality of unlocking operations can be performed by a single operation using an interlocking mechanism so that a transfer belt unit can be easily replaced. .

  In order to solve the above problems, an image forming apparatus according to the present invention is in contact with an apparatus housing, a plurality of photosensitive drums detachably arranged on the apparatus casing, and all of the plurality of photosensitive drums. The belt posture can be displaced between a first posture that is in contact with a second posture that contacts only one of the plurality of photosensitive drums, and a third posture that is not in contact with all of the plurality of photosensitive drums. A transfer belt unit detachably attached to the apparatus housing, comprising: a transfer belt that is circulated and movable over a roller; and a belt displacement control mechanism that controls displacement of the belt posture of the transfer belt; and the apparatus An opening / closing member provided in the housing and opened / closed when the plurality of photosensitive drums are attached to and detached from the apparatus housing; and a lock lever that locks the opening / closing member; On the other hand, the belt displacement control mechanism Combined, configured and a linkage mechanism for controlling so as to displace the position of the transfer belt to the third position in conjunction with the unlocking of the lock lever with respect to the belt displacement control mechanism.

  According to the present invention, since a plurality of lock mechanisms are unlocked by a single operation by an interlocking mechanism, it is possible to provide an image forming apparatus in which the transfer belt unit can be easily replaced.

1 is a cross-sectional view showing an internal configuration of a full-color image forming apparatus (printer, apparatus casing) according to Embodiment 1 of the present invention. 1 is an external perspective view of a printer according to Embodiment 1. FIG. (a), (b), (c) is a diagram illustrating a state in which the transfer belt of the transfer belt unit of the printer according to the first embodiment is controlled in position by the belt position control mechanism with respect to the photosensitive drum of the image forming unit. is there. FIG. 3 is a perspective view illustrating a state when the transfer belt unit and four image forming units of the printer according to the first embodiment are mounted in the apparatus housing. FIG. 5 is a diagram illustrating a unit lock cover that prohibits removal of the transfer belt unit and four image forming units in the state of FIG. 4.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is an external perspective view of a full-color image forming apparatus (hereinafter simply referred to as a printer or an apparatus housing) 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 is in contact with the lower running portion surface 8a of the transfer belt 8 from right to left in FIG. 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.

  A belt position control mechanism, which will be described in detail later, 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 40, which will be described later in detail, is disposed because it is a cross-sectional view in FIG. 1.

  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.

  This duplex printing transport unit 7 has a start return path 39a that branches rightward in the figure from just before the paper discharge roller pair 38, an intermediate return path 39b that bends downward, and a left lateral direction opposite to the above. Thus, a return path 39 including a terminal return 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 end return path 39 c joins the conveyance path to the pair of standby conveyance rollers 34 corresponding to the sheet feeding cassette 30 b below the sheet feeding unit 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 30 a and 30 b shown in FIG. 1 are attached to the front of the apparatus housing 1 by a handle 43 so that they can be inserted and removed.

  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 operations 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 are performed by opening the front door 42 shown in FIG. 2 and further the unit lock cover 40 shown in FIG. And the kits are configured to be exchanged in the longitudinal direction (front door direction).

  FIGS. 3A, 3B, and 3C are diagrams illustrating a state in which the transfer belt 8 of the transfer belt unit 3 is controlled in position with respect to the photosensitive drum 10 of the image forming unit 2 by the belt position control mechanism. is there. 3 (a), (b), and (c), the same components as those shown in FIG. 1 are denoted by the same reference numerals as those in FIG.

  As described above, the primary transfer roller 23 (23y, 23m, 23c, 23k) is integrally incorporated in the belt position control mechanism 47 shown in FIGS. 3 (a), (b), and (c). As shown in FIG. 3A, the primary transfer roller 23 is held by a transfer bearing base 48, respectively.

  A slide pin 49 is attached to the transfer bearing base 48. The slide pins 49 of the transfer bearing base 48 of the primary transfer rollers 23y, 23m, and 23c are slidably fitted into the slide groove 52 at three locations on the YMC slide vertical plate 51, respectively.

  Further, the slide pin 49 of the transfer bearing base 48 of the primary transfer roller 23k is slidably fitted into the slide groove 54 of the K slide vertical plate 53. FIG. 3A shows a state in which all four slide pins 49 are moved to the lowermost ends of the slide grooves 52 and 54.

  3A, the belt position control mechanism 47 lowers all four primary transfer rollers 23 and presses them against the photosensitive drums 10 (10y, 10m, 10c, 10k) via the transfer belt 8. FIG. The position of the transfer belt 8 is set to the full color mode, and the setting is locked.

  3 (a), 3 (b), and 3 (c) only show the front side surface, the transfer bearing base 48, the slide pin 49, the YMC slide vertical plate 51, and the K slide vertical plate 53 are It is arranged on both sides of the transfer belt unit 3 via a central cam plate (not shown).

  FIG. 3B shows the other three primary transfer rollers 23y while the belt position control mechanism 47 maintains the pressure contact of the primary transfer roller 23k via the transfer belt 8 to the photosensitive drum 10k of the image forming unit 9k. , 23m and 23c are moved upward to separate the transfer belt 8 from the photosensitive drums 10y, 10m and 10c, and the position of the transfer belt 8 is set to the monochrome mode.

  That is, in FIG. 3 (b), the position of the K slide vertical plate 53 is not changed from that in FIG. 3 (a) and is still locked in the monochrome position, but the mode switching cam 55 is in the position of FIG. 3 (a). , The position of the YMC slide vertical plate 51 is moved in the direction of the driven roller 22.

  As a result, the slide pin 49 of the transfer bearing base 48 of the primary transfer rollers 23y, 23m, and 23c shown in FIG. 3 (a) moves to the top of the slide groove 52 as shown in FIG. 3 (b). Accordingly, the transfer bearing base 48 is rotated upward with the support shaft 56 as a fulcrum.

  By the upward rotation of the transfer bearing base 48, the primary transfer rollers 23y, 23m, and 23c held by the transfer bearing base 48 are lifted upward to release the pressure on the transfer belt 8, and the transfer belt 8 is The color mode is unlocked at a distance from the photosensitive drums 10y, 10m, and 10c, and only the monochrome mode is set.

  FIG. 3 (c) shows the driven roller until the belt position control mechanism 47 rotates the separation cam lever 57 90 degrees toward the driven roller 22 until the K slide vertical plate 53 comes into contact with the right end of the YMC slide vertical plate 51. A state in which the mode switching cam 55 is rotated to the transfer position shown in FIG.

  However, in the case of FIG. 3C, the K slide vertical plate 53 is in contact with the right end portion of the YMC slide vertical plate 51 even when the mode switching cam 55 returns to the transfer position similar to FIG. Therefore, the YMC slide vertical plate 51 cannot return to the transfer position shown in FIG. 3A while maintaining the non-transfer position shown in FIG.

  Here, since the K slide vertical plate 53 has moved to the left, the slide pin 49 of the transfer bearing base 48 of the primary transfer roller 23k with respect to the photosensitive drum 10k of the image forming unit 9k is moved to the K slide vertical plate 53, that is, the slide groove 54. Is moved to the uppermost part of the slide groove 54 with the movement to the left.

  When the slide pin 49 is moved to the uppermost part of the slide groove 54, the transfer bearing base 48 of the primary transfer roller 23k rotates upward with the support shaft 58 as a fulcrum, and the primary transfer roller 23k is lifted and the transfer belt 8 is moved. The non-transfer mode in which the transfer belt 8 is separated from the photosensitive drum 10k, the transfer belt 8 is separated from the photosensitive drum 10 together with all the four primary transfer rollers 23 is set.

  In this state, when the separation cam lever 57 rotates 90 degrees toward the driving roller 21 and the K slide vertical plate 53 moves toward the driving roller 21, it is biased toward the driving roller 21 by a spring mechanism (not shown). The YMC slide vertical plate 51 is moved to the transfer position shown in FIG. 3A as the K slide vertical plate 53 is moved because the mode switching cam 55 is already at the transfer position.

  Here, the separation cam lever 57 automatically rotates according to the setting mode, but can also be rotated manually. As described above, even if the mode switching cam 55 is at the color transfer position shown in FIG. 3A or the monochrome transfer position shown in FIG. And the all non-transfer mode shown in FIG. 3C can be set.

  In other words, the contact relationship between the transfer belt 8 and the photosensitive drum 10 is the same regardless of whether the transfer belt 8 and the photosensitive drum 10 are in the full color mode or the monochrome mode as well as the all non-transfer mode. The transfer belt unit 3 as a whole can be brought into a non-contact state from the photosensitive drum 10 by being released.

  FIG. 4 is a perspective view showing a state when the transfer belt unit 3 and the four image forming units 9m, 9c, 9y, and 9k are mounted in the apparatus housing 1. In FIG. 4, the same components as those shown in FIGS. 1 to 3 are denoted by the same reference numerals as those in FIGS.

  As shown in FIG. 4, the transfer belt unit 3 slides on the front frame 59a, the rear frame 59b, the YMC slide vertical plate 51, and the K slide vertical plate 53 shown in FIGS. 3 (a), (b), and (c). It is held via a driving roller 21 and a driven roller 22 on a unit frame made of a slide face plate or the like that can be held.

  The front YMC slide vertical plate 51 and K slide vertical plate 53 shown in FIG. 3 are arranged in a state of being covered by the front frame 59a shown in FIG. A discharge port cap 61 for opening and closing the waste toner discharge port is disposed at the back end of the belt cleaner 27.

  At the center of the front frame 59 a of the transfer belt unit 3, a unit handle 62 that is used when the transfer belt unit 3 is attached to and detached from the apparatus housing 1 is formed. Further, two handle plates 63 are disposed above the upper surface of the transfer belt 8 so as to be passed between the front frame 59a and the rear frame 59b.

  The two handle plates 63 are respectively attached with handles 64 whose both ends are slidable to be carried when the transfer belt unit 3 is outside the apparatus housing 1.

  Below the transfer belt unit 3, four image forming units 9 (9m, 9c, 9y, 9k) are arranged. Each of the four image forming units 9 is provided with a handle 65 that is picked up when the image forming unit 9 is attached to or detached from the apparatus housing 1.

  In FIG. 4, the contact state between the toner image transfer surface on the lower surface of the transfer belt 8 and the photosensitive drum 10 of the image forming unit 9 is not visible in the figure, but the separation cam lever 57 is in the vertical position. It can be seen that the full color printing mode shown in FIG. 3A or the monochrome printing mode shown in FIG. 3B is set.

  In this state, the unit lock cover 40 shown in FIG. 1 is unlocked, the unit lock cover 40 is opened, the unit handle 62 is put in hand, and the transfer belt unit 3 is pulled out to the front of the apparatus housing 1. Then, the lower surface of the transfer belt 8 and the upper surface of the photosensitive drum 10 are in sliding contact with each other and both are damaged.

  Therefore, the separation cam lever 57 is rotated 90 degrees by hand counterclockwise from the vertical position, and as shown in FIG. 3C, the transfer belt 8 together with all four primary transfer rollers 23 together with the photosensitive drum 10 The transfer belt unit 3 must be pulled out after setting to the all non-transfer mode away from.

  FIG. 5 is a diagram specifically showing the unit lock cover 40 shown in FIG. 1 arranged on the front surface in the state of FIG. A lock cover opening / closing knob 66 is disposed near the right end of the unit lock cover 40.

  The lock cover opening / closing knob 66 is rotatably attached to a cover lock position shown in FIG. 5 and a cover lock release position rotated 90 degrees counterclockwise as indicated by an arrow b.

  When the lock cover opening / closing knob 66 is rotated to the cover lock position and prohibits the opening / closing of the unit lock cover 40, the transfer belt unit 3 and the four image forming units 9 can be removed from the apparatus housing 1 by the unit lock. It is prohibited by the cover 40.

  In this example, the inside of the lock cover opening / closing knob 66 is formed in a cavity, although not particularly shown. However, a plate-like body having a radius extending from the knob shaft to the inner peripheral surface is disposed at a predetermined location.

  When the lock cover opening / closing knob 66 is in the cover lock position as shown in FIG. 5, this plate-like body is formed in correspondence with the position where it comes into contact with the right side surface of the separation cam lever 57 in the vertical position shown in FIG. ing. That is, the separation cam lever 57 shown in FIG. 4 enters the inside of the lock cover opening / closing knob 66 in the state of FIG.

  When the user or maintenance worker takes out the transfer belt unit 3 from the apparatus housing 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 40 shown in FIGS. 1 and 5, the lock cover opening / closing knob 66 is twisted 90 degrees counterclockwise.

  As a result, the lock of the unit lock cover 40 is released and the unit lock cover 40 can be opened, and the separation cam lever 57 rotates 90 degrees counterclockwise from the vertical position in conjunction with the lock cover opening / closing knob 66. (If it is rotated 90 degrees from the original position, it is as it is).

  As a result, the user or the maintenance worker immediately takes the unit handle 62 without paying attention to the engagement state between the transfer belt unit 3 and the photosensitive drum 10 of the image forming unit 9, and removes the transfer belt unit 3. It can be taken out from the device housing 1.

  As described above, according to this embodiment, since the plurality of lock mechanisms are unlocked by one operation by the interlocking mechanism, the transfer belt (secondary transfer belt) unit is maintained, inspected, replaced, etc. It can be easily performed without error without causing damage or the like due to interference such as sliding contact with the drum.

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]

A device housing;
A plurality of photosensitive drums detachably arranged in the apparatus housing;
A first position that contacts all of the plurality of photosensitive drums, a second position that contacts only one of the plurality of photosensitive drums, and a third position that does not contact all of the plurality of photosensitive drums. And a belt displacement control mechanism for controlling the displacement of the belt posture of the transfer belt. A removable transfer belt unit;
An opening / closing member provided in the apparatus casing and opened and closed when the plurality of photosensitive drums are attached to and detached from the apparatus casing;
A lock lever for locking the opening and closing member;
On the one hand, it engages with the lock lever, and on the other hand, it engages with the belt displacement control mechanism, and the posture of the transfer belt is changed to the third posture in conjunction with unlocking of the lock lever with respect to the belt displacement control mechanism. An interlocking mechanism for controlling the displacement,
An image forming apparatus comprising:
[Appendix 2]

When the interlock mechanism rotates to move the lock lever to the unlock position, the belt displacement control mechanism is interlocked with the transfer belt when the interlock mechanism and the belt displacement control mechanism are engaged. Formed so as to rotate in a direction to displace the posture of the third posture to the third posture,
The image forming apparatus as set forth in appendix 1, wherein:
[Appendix 3]

The plurality of photosensitive drums are respectively incorporated in a plurality of image forming units that are detachable from the apparatus housing so as to form toner images of different colors.
The image forming apparatus as set forth in appendix 1, wherein:
[Appendix 4]

The different color toner images are images of yellow, magenta, cyan, and black toners,
The image forming apparatus according to Supplementary Note 3, wherein

  The present invention can be used in an image forming apparatus in which a transfer belt unit can be easily replaced because a plurality of lock mechanisms are unlocked by a single operation by an interlocking mechanism.

1 Full-color image forming device (printer, device housing)
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 conveyance roller pair 36 Unloading roller pair 37 Paper discharge tray 38 Paper discharge roller pair 39 Return path 39a Start return path 39b Intermediate return path 39c End return path 41 (41a, 41b, 41c, 41d) 41e) Return roller pair 40 Unit lock cover 42 Front door 43, 44 Handle 45 Opening / closing member 46 Operation panel 47 Belt position control mechanism 48 Transfer bearing base 49 Slide pin 51 YMC slide vertical plate 52 Slide groove 53 K slide vertical plate 54 Slide groove 55 Mode switching cam 56 Support shaft 57 Separation cam lever 58 Support shaft 59a Front frame 59b Rear frame 61 Outlet cap 62 Unit handle 63 Handle plate 64, 65 Handle 66 Lock cover opening / closing knob

Claims (3)

A device housing;
A plurality of photosensitive drums detachably arranged in the apparatus housing;
A first position that contacts all of the plurality of photosensitive drums, a second position that contacts only one of the plurality of photosensitive drums, and a third position that does not contact all of the plurality of photosensitive drums. And a belt displacement control mechanism for controlling the displacement of the belt posture of the transfer belt. A removable transfer belt unit;
An opening / closing member provided in the apparatus casing and opened and closed when the plurality of photosensitive drums are attached to and detached from the apparatus casing;
A lock lever for locking the opening and closing member;
On the one hand, it engages with the lock lever, and on the other hand, it engages with the belt displacement control mechanism, and the posture of the transfer belt is changed to the third posture in conjunction with unlocking of the lock lever with respect to the belt displacement control mechanism. An interlocking mechanism for controlling the displacement,
Equipped with a,
When the interlock mechanism rotates to move the lock lever to the unlock position, the belt displacement control mechanism is interlocked with the transfer belt when the interlock mechanism and the belt displacement control mechanism are engaged. An image forming apparatus, wherein the image forming apparatus is formed so as to be rotated in a direction to displace the first position in the third position . The plurality of photosensitive drums are respectively incorporated in a plurality of image forming units that are detachable from the apparatus housing so as to form toner images of different colors.
  The image forming apparatus according to claim 1. The different color toner images are images of yellow, magenta, cyan, and black toners,
  The image forming apparatus according to claim 2.