JP2022164328A - Image forming apparatus - Google Patents

Abstract

To provide an image forming apparatus that can locate a developing roller at a contact position when a cover is opened.SOLUTION: An image forming apparatus comprises: a cam 150 that moves a developing roller between a contact position at which the developing roller is in contact with a photoconductor drum and a separation position at which the developing roller is separated from the photoconductor drum; a sector gear 210; and a translation member 220 that translates frontward and backward. When the translation member 220 moves frontward in conjunction with the movement of a cover from a closed position to an open position from a state in which the developing roller is at the separation position, a rack gear part 222 meshes with a gear tooth part 211A of the sector gear 210 to rotate the sector gear 210 and the cam 150, thereby moving the developing roller from the separation position to the contact position. When the translation member 220 moves frontward in conjunction with the movement of the cover from the closed position to the open position from a state in which the developing roller is at the contact position, the rack gear part 222 faces a missing tooth part 211B of the sector gear 210 without meshing with the gear tooth part 211A.SELECTED DRAWING: Figure 14

Description

The present invention relates to an image forming apparatus in which a developing roller is movable between a contact position in contact with a photosensitive drum and a separated position in which the developing roller is separated from the photosensitive drum.

2. Description of the Related Art Conventionally, an image forming apparatus is known in which a developing roller is movable between a contact position in contact with a photosensitive drum and a spaced position away from the photosensitive drum (Patent Document 1). In this technology, when the cover is opened while the developing roller is in the separated position, the cam follower rotates and the contact portion of the cam follower is disengaged from the first cam portion of the cam, whereby the cam follower presses the developing cartridge. It slides and retreats from the position to the non-pressing position, whereby the developing roller of the developing cartridge moves from the separated position to the contact position.

Japanese Patent Application Laid-Open No. 2021-015140

By the way, the inventors of the present application devised a structure that is different from the conventional structure, and that allows the developing roller to be in the contact position when the cover is opened.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming apparatus in which the developing roller can be placed in a contact position when the cover is opened.

An image forming apparatus for achieving the above object comprises a housing having an opening, a cover movable between a closed position for closing the opening and an open position for opening the opening, a photosensitive drum, and a photosensitive drum. A development roller for supplying toner and a separation mechanism capable of moving the development roller between a contact position where the development roller contacts the photosensitive drum and a separation position where the development roller is separated from the photosensitive drum.
The separating mechanism is a rotatable cam for moving the developing roller between the contact position and the separated position, and a sector gear that rotates in conjunction with the rotation of the cam and has gear teeth. The position when the cover is in the closed position interlocking with the movement of the sector gear having the gear tooth portion and the toothless portion in which the gear tooth is not formed, and the movement between the closed position and the open position of the cover. a linear motion member that linearly moves between a first position and a second position that is a position when the cover is in the open position, the linear motion member having a rack gear portion that can mesh with the gear tooth portion; Prepare.
When the linear motion member moves from the first position to the second position in conjunction with the movement of the cover from the closed position to the open position from the state where the developing roller is at the separated position, the rack gear portion meshes with the gear tooth portion. The sector gear and the cam are rotated to move the developing roller from the separated position to the contact position, and the first position to the second position is interlocked with the movement of the cover from the closed position to the open position from the contact position of the developing roller. , the rack gear portion faces the toothless portion and moves without meshing with the gear tooth portion.

According to such a configuration, when the cover is opened, the developing roller can be placed in the contact position.

In the image forming apparatus described above, the spacing mechanism includes a swinging member that can swing with respect to the linear motion member and linearly moves together with the linear motion member. It has a contacted portion that can be contacted by a swinging member that linearly moves together with the direct-acting member while facing the member, and the swinging member linearly moves in conjunction with the movement of the cover from the closed position to the open position. When the member comes into contact with the contacted portion while moving from the first position to the second position, it swings and retracts so that the sector gear does not rotate and is interlocked with the movement of the cover from the open position to the closed position. When the direct-acting member contacts the contacted portion when moving from the second position to the first position, the contacted portion is pushed to rotate the sector gear, the gear tooth portion and the rack gear portion are meshed, and the linear-acting member moves to the first position. When the rack gear portion and the gear tooth portion are engaged when moving from the second position to the first position, the sector gear and the cam may be rotated to move the developing roller from the contact position to the separated position.

According to this, when the cover is closed, the gear tooth portion of the sector gear and the rack gear portion of the linear motion member can be meshed with each other by the rocking member. Further closing the cover rotates the sector gear and the cam, thereby moving the developing roller from the contact position to the separated position. On the other hand, when the swinging member comes into contact with the contacted portion when the cover is opened, the swinging member swings back and does not rotate the sector gear, so the developing roller is maintained at the contact position. can be left as is.

The image forming apparatus described above is a drawer that can move through an opening with respect to a housing, has a photosensitive drum, a side wall that supports the photosensitive drum, and has a second opening in the side wall; a developer cartridge having a roller and detachable from the drawer, and the separation mechanism has a waiting position, which is a position when the developing roller is in the contact position, and a position when the developing roller is in the separated position due to the rotation of the cam. A cam follower that slides along the direction of the rotation axis of the developing roller between a projecting position that is the position of and enters the second opening to press the developing cartridge when it is at the projecting position, and when it is at the standby position When the developing cartridge is pressed by the cam follower that moves from the standby position to the projecting position, the developing roller moves to a position where the developing roller is separated, and the cam follower moves from the projecting position to the standby position. The developing roller may be supported by the drawer so that the developing roller moves to the contact position when it is no longer pressed by the drawer.

According to this, when the developing roller is in the contact position after the cover is opened, the cam follower is in the standby position, so the cam follower can be removed from the second opening of the side wall of the drawer. Thereby, the drawer can be moved with respect to the housing, and the developer cartridge can be attached/detached to/from the drawer.

In the above-described image forming apparatus, the sector gear faces a portion of the linear motion member where no gear teeth are formed, and the gear tooth portion does not mesh with the rack gear portion when the linear motion member is at the first position. be able to.

According to this, the sector gear and the cam are allowed to rotate when the cover is closed. This makes it possible to rotate the cam to move the developing roller between the contact position and the separated position while the cover is closed.

In the image forming apparatus described above, the cam has a disk portion and a first gear portion formed on the outer circumference of the disk portion, and the sector gear has a gear tooth portion and a toothless portion; It can be configured as a two-stage gear having a first gear portion and a second gear portion that meshes with each other.

According to this, compared with the case where the sector gear is formed on the cam, it is possible to increase the degree of freedom in designing the spacing mechanism. Also, the spacing mechanism can be made smaller than when an idle gear is arranged between the sector gear and the cam.

In the image forming apparatus described above, the separating mechanism may further include a spring that biases the cam follower from the projecting position toward the standby position.

In the image forming apparatus described above, the cam is a first cam portion that can contact the cam follower, and guides the cam follower between the projecting position and the standby position; The image forming apparatus includes a clutch that can be switched between a transmission state in which the driving force is transmitted to the developing roller and a disconnected state in which the driving force is not transmitted to the developing roller, and a clutch guided by the second cam portion. It is possible to further include a lever that swings with the clutch and is capable of switching the clutch between the transmission state and the disengagement state.

In the image forming apparatus described above, the clutch has a planetary gear mechanism, and the lever is guided by the second cam portion to engage with one element of the planetary gear mechanism to bring the clutch into the transmission state. and a non-transmitting position disengaging one element of the planetary gear mechanism to disengage the clutch.

According to the present invention, the developing roller can be placed in the contact position when the cover is opened.

1 is a diagram showing a schematic configuration of an image forming apparatus according to an embodiment; FIG. FIG. 3 is a perspective view of the drawer, cam and cam follower; It is the perspective view (a) of developer cartridge, and the side view (b). It is a figure which shows the structure around a developing cartridge, and is the figure (a) which shows when a cam follower is located in a standby position, and the figure (b) which shows when it is located in a projecting position. FIG. 4 is a diagram showing the inner surface of the side frame of the drawer; It is the perspective view (a) which looked at the cam from the 1st surface side, and the perspective view (b) which looked at the cam from the 2nd surface side. 3A and 3B are side views of a cam, a cam follower, a clutch, and a lever, showing the developing roller at the contact position (a) and at the separated position; FIG. It is the side view which looked at the drive transmission mechanism from the left side. It is the side view which looked at the drive transmission mechanism from the right side. It is the exploded perspective view (a) which looked at the clutch from the sun gear side, and the exploded perspective view (b) which looked at the carrier side. FIG. 1(a) is an exploded perspective view of the lever, FIG. 1(b) shows a state where the rotation of the first lever is restricted by the rotation restricting portion, and FIG. (c). FIG. 10 is a diagram showing a state in which the first lever of the levers in the transmission position has swung relative to the second lever when the cam rotates in the reverse direction; FIG. 10 is a diagram showing the separating mechanism in a state where the direct-acting member is positioned at the first position and the developing roller is positioned at the separating position; It is the figure which expanded and showed a cam, a sector gear, a direct-acting member, and a rocking member. FIG. 10 is a diagram showing the separation mechanism in a state where the direct-acting member is positioned at the first position and the developing roller is positioned at the contact position; FIG. 10 is a diagram showing a state in which the swinging member contacts the protrusion of the sector gear and swings to the retracted position while the linear motion member is moving from the first position toward the second position; FIG. 10 is a diagram showing the spacing mechanism in a state where the linear motion member is positioned at the second position; FIG. 10 is a diagram showing a state in which the swinging member comes into contact with the protrusion of the sector gear while the linear motion member is moving from the second position toward the first position; FIG. 10 is a view showing a state in which the swinging member pushes the protrusion to rotate the sector gear, and the gear tooth portion of the sector gear and the rack gear portion of the direct-acting member are meshed; FIG. 10 is a diagram showing a state in which the rack gear and the cam are rotated by movement of the direct-acting member after the gear tooth portion and the rack gear portion are meshed; It is a figure which shows the state in which the direct-acting member was located in the 1st position.

As shown in FIG. 1, an image forming apparatus 1 according to the embodiment is a color printer, and mainly includes a housing 10, a cover 11, a sheet feeding section 20, an image forming section 30, and a control section 2. I have. In this specification, for the sake of convenience, directions such as the front and rear directions are described with the left side of FIG. 1 from which the sheet tray 21 is pulled out as the front side. That is, the left side of FIG. 1 is the front, the right side is the rear, and the top and bottom are the top and bottom.

The housing 10 has a first opening 10A on the front side. In this embodiment, the first opening 10A corresponds to the "opening". The cover 11 is movable between a closed position that closes the first opening 10A indicated by solid lines and an open position that opens the first opening 10A indicated by phantom lines. The housing 10 is provided with a cover sensor (not shown) that detects the open/closed state of the cover 11, and the control unit 2 can determine the open/closed state of the cover 11 based on the signal from the cover sensor. .

The sheet supply unit 20 is provided in the lower part of the housing 10 and includes a sheet tray 21 that stores the sheets S and a supply mechanism 22 that supplies the sheets S from the sheet tray 21 to the image forming unit 30 . The sheet tray 21 is configured to be removable by being pulled forward from the housing 10 . The supply mechanism 22 is provided in the front part inside the housing 10 and includes a paper feed roller 23 , a separation roller 24 , a separation pad 25 and a registration roller 27 . A sheet S in this specification is a medium on which an image can be formed by the image forming apparatus 1, and includes plain paper, envelopes, postcards, thin paper, thick paper, glossy paper, resin sheets, stickers, and the like.

In the sheet supply unit 20 , the sheets S are fed out from the sheet tray 21 by the sheet feed roller 23 and then separated one by one between the separation roller 24 and the separation pad 25 . After that, the leading edge position of the sheet S is regulated by the registration rollers 27 that are not rotating, and then the registration rollers 27 are rotated to supply the sheet S to the image forming section 30 .

Further, in the sheet supply section 20, a paper feed sensor 28A, a pre-registration sensor 28B, and a post-registration sensor 28C are provided. The paper feed sensor 28A is provided immediately downstream of the paper feed roller 23 and the separation roller 24 in the sheet S conveying direction. The pre-registration sensor 28B is provided upstream of the registration rollers 27 in the transport direction. The post-registration sensor 28C is provided downstream of the registration rollers 27 in the transport direction.

The image forming section 30 includes an exposure device 40 , a drawer 90 (see FIG. 2) having a plurality of photosensitive drums 50 , a plurality of developing cartridges 60 , a conveying device 70 and a fixing device 80 .

The exposure device 40 has a laser diode, a deflector, a lens and a mirror (not shown). The exposure device 40 is configured to emit a plurality of laser beams for exposing a plurality of photosensitive drums 50 to scan the surfaces of the photosensitive drums 50 .

The photosensitive drums 50 include a first photosensitive drum 50Y for yellow, a second photosensitive drum 50M for magenta, a third photosensitive drum 50C for cyan, and a fourth photosensitive drum 50K for black. . In the present specification and drawings, members provided corresponding to the respective colors of yellow, magenta, cyan, and black are denoted by Y, M, C, and K, respectively, when distinguishing the colors. is shown. On the other hand, when the description is made without distinguishing colors, the symbols Y, M, C, and K are omitted, and the names 1, 2, etc. are omitted.

A developing cartridge 60 is provided corresponding to each photosensitive drum 50 . Specifically, the developing cartridge 60 includes a first developing cartridge 60Y having a first developing roller 61Y for supplying toner to the first photosensitive drum 50Y, and a second developing cartridge 60Y for supplying toner to the second photosensitive drum 50M. A second developing cartridge 60M having a developing roller 61M, a third developing cartridge 60C having a third developing roller 61C for supplying toner to the third photosensitive drum 50C, and a toner cartridge for supplying toner to the fourth photosensitive drum 50K. and a fourth developer cartridge 60K having a fourth developer roller 61K.

The first developing roller 61Y, the second developing roller 61M, the third developing roller 61C, and the fourth developing roller 61K are arranged in this order from upstream to downstream in the sheet S movement direction.

Each developing cartridge 60 is located at a contact position where the developing roller 61 contacts the corresponding photosensitive drum 50, indicated by a solid line in FIG. It is movable to and from a position in a spaced position spaced apart from 50 .

As shown in FIG. 2, the photosensitive drum 50 is rotatably supported by the drawer 90 . The drawer 90 also detachably supports the developer cartridge 60 . That is, the developer cartridge 60 is attachable to and detachable from the drawer 90 . The drawer 90 is movable with respect to the housing 10 through the first opening 10A formed by opening the cover 11 (see FIG. 1) of the housing 10 . Also, the drawer 90 is detachable from the housing 10 .

The drawer 90 includes a pair of side frames 91, which are an example of side walls, spaced apart in the axial direction of the photosensitive drum 50, a connecting frame 92 connecting the front portions of the pair of side frames 91, and the pair of side frames. It has a connection frame 93 that connects the rear portions of 91 to each other. The pair of side frames 91 includes a right side frame 91R and a left side frame 91L. The drawer 90 is provided with chargers 52 (see FIG. 1) for charging the photosensitive drums 50 arranged opposite to the respective photosensitive drums 50 .

Although illustration of the detailed structure is omitted, the pair of side frames 91 support the end portions of the photosensitive drums 50 . The drawer 90 has a second opening 91A in one side frame 91, here the left side frame 91L. The second opening 91A is formed as a notch recessed downward in the upper edge of the side frame 91L. As a result, the second opening 91A penetrates the side frame 91L in the left and right direction, and allows a cam follower 170, which will be described later, to enter.

The image forming apparatus 1 includes a separation mechanism 5 capable of moving the developing roller 61 between a contact position at which the developing roller 61 contacts the corresponding photosensitive drum 50 of the plurality of photosensitive drums 50 and a separation position at which the developing roller 61 is separated from the photosensitive drum 50 . Prepare. The spacing mechanism 5 includes a cam 150 (150Y, 150M, 150C, 150K) rotatable around an axis parallel to the rotation axis 61X (see FIG. 1) of the developing roller 61, a support shaft 179, a cam follower 170, a first and a spring 176 . In this embodiment, the first spring 176 corresponds to a "spring".

The cam 150 has a first cam portion 152 that protrudes in the direction of the rotation axis of the developing roller 61 (hereinafter simply referred to as "the direction of the rotation axis").

The support shaft 179 is a shaft that extends horizontally. The support shaft 179 is provided on the support plate 102 (see FIG. 9) arranged inside the housing 10 .

Cam follower 170 engages with support shaft 179 and is slidable along the direction of the rotation axis. The cam follower 170 has a contact portion 172 that can come into contact with the first cam portion 152 . Cam follower 170 contacts cam surface 152</b>F, which is the end surface of first cam portion 152 of cam 150 . The cam follower 170 is guided by the first cam portion 152 as the cam 150 rotates, and slides between the standby position shown in FIG. 4(a) and the projecting position shown in FIG. 4(b). The standby position is the position when the developing roller 61 is in the contact position, and the projecting position is the position when the developing roller 61 is in the separated position.

When the cam follower 170 is at the projecting position, it enters the second opening 91A to press the developing cartridge 60 to position the developing roller 61 at the separated position. Position in contact position.

Returning to FIG. 2, the cam 150 and cam follower 170 are provided corresponding to each developing cartridge 60 . Cam 150 and cam follower 170 are arranged laterally outside of left side frame 91L. Detailed structures of cam 150 and cam follower 170 will be described later.

The drawer 90 is provided with a contact portion 94 that contacts a slide member 64, which will be described later, on the upper portions of the side frames 91R and 91L. The abutted portion 94 is arranged, for example, around an axis along a third direction (vertical direction) orthogonal to both a first direction parallel to the axial direction of the photosensitive drum 50 and a second direction in which the photosensitive drums 50 are arranged. It consists of rotatable rollers.

The drawer 90 also includes a pressing member 95 provided corresponding to each developing cartridge 60 . The pressing members 95 are provided at both ends of the photosensitive drum 50 in the axial direction for each developing cartridge 60 . The pressing member 95 is urged rearward by a spring 95A (see FIGS. 4A and 4B), and presses the protrusion 63D of the developing cartridge 60 when the developing cartridge 60 is attached to the drawer 90. Then, the developing roller 61 is brought into contact with the corresponding photosensitive drum 50 .

As shown in FIGS. 3A and 3B, the developer cartridge 60 (60Y, 60M, 60C, 60K) has a case 63 containing toner, a slide member 64, and a coupling 65. As shown in FIG.

The case 63 has a first protrusion 63A and a second protrusion 63B on one side surface as protrusions protruding in the rotation axis direction. The first protrusion 63A is arranged coaxially with the rotation axis 61X of the developing roller 61 and protrudes in the direction of the rotation axis. The second projecting portion 63B is arranged at a predetermined distance from the first projecting portion 63A. In this embodiment, the second projecting portion 63B is arranged above the first projecting portion 63A. Both the first projecting portion 63A and the second projecting portion 63B are rollers rotatable around an axis parallel to the rotation axis direction. Although not shown, the case 63 is also provided with a first projecting portion 63A and a second projecting portion 63B on the other side surface at positions symmetrical to the one side surface.

Further, the case 63 has a protrusion 63</b>D that is pressed by the pressing member 95 on the upper front side of the side surface. The protrusions 63D are provided at both ends of the case 63 in the rotation axis direction.

The coupling 65 engages with a coupling shaft 119 to be described later, and receives rotational driving force from the coupling shaft 119 .

The slide member 64 is a member that can slide in the rotation axis direction with respect to the case 63 . The slide member 64 is slidable in the rotational axis direction by being pressed by the cam follower 170 .

As shown in FIGS. 4A and 4B, the slide member 64 includes a shaft 191, a first contact member 192, and a second contact member 193. As shown in FIGS. The first contact member 192 is fixed to one end of the shaft 191 and the second contact member 193 is fixed to the other end of the shaft 191 .

The shaft 191 is disposed through a hole formed in the case 63 and extending in the rotation axis direction, and is slidably supported by the case 63 .

The first contact member 192 has a pressing surface 192A, which is an end surface in the rotation axis direction, and an inclined surface 192B inclined with respect to the rotation axis direction. The pressing surface 192A is a surface pressed by the cam follower 170 . When the slide member 64 is pressed in the rotation axis direction by the cam follower 170, the inclined surface 192B abuts against the abutted portion 94 of the drawer 90 and directs the developing cartridge 60 in a direction parallel to the moving direction of the sheet S. energized to move the developer cartridge 60 . The slope 192B is inclined from one end of the shaft 191 toward the other end so as to be positioned in the direction (forward) from the photosensitive drum 50 toward the corresponding developing roller 61 in the second direction.

The second contact member 193 has a slope 193B that is inclined similarly to the slope 192B of the first contact member 192 . When the slide member 64 is pressed in the rotation axis direction by the cam follower 170, the inclined surface 193B also abuts against the abutted portion 94 of the drawer 90, and attaches the developing cartridge 60 in a direction parallel to the moving direction of the sheet S. force to move the developer cartridge 60 .

A spring 194 is arranged between the first contact member 192 and the case 63 to bias the slide member 64 toward one side of the rotation axis direction, that is, leftward in this case. The spring 194 is a compression coil spring and is arranged outside the shaft 191 so that the shaft 191 passes through the coil.

When the developing cartridge 60 is pressed by the cam follower 170 that has moved from the standby position shown in FIG. 4A to the projecting position shown in FIG. The developing roller 61 is supported by the drawer 90 so as to move to the separated position, more specifically, to the front by contacting the abutted portion 94 of the developing roller 61 . Further, when the developing cartridge 60 is no longer pressed by the cam follower 170 that has moved from the projecting position to the standby position, the pressing member 95 presses the projection 63D, and the developing roller 61 is at the contact position. is supported by a drawer 90 so as to move rearward.

As shown in FIG. 5, the drawer 90 has a first support surface 96A and a second support surface 96B as support surfaces on the inner surface of one side frame 91L. The first support surface 96A and the second support surface 96B respectively support the first projecting portion 63A and the second projecting portion 63B from below when the developing roller 61 moves from the contact position to the separated position. The first support surface 96A and the second support surface 96B extend in the sheet S moving direction. The first support surface 96A is arranged to support the first protrusion 63A. The first support surface 96</b>A also functions to guide and vertically position the developing roller 61 when the developing cartridge 60 is attached to the drawer 90 . The second support surface 96B is arranged above the first support surface 96A so as to support the second protrusion 63B. Although not shown, the drawer 90 also has a first support surface 96A and a second support surface 96B on the inner surface of the other side frame 91R, which are bilaterally symmetrical with the one side frame 91L.

When the developing roller 61 is positioned at the contact position where the developing roller 61 contacts the photosensitive drum 50, the first projecting portion 63A is positioned on the first supporting surface like the first developing cartridge 60Y, the second developing cartridge 60M and the third developing cartridge 60C in FIG. It is located toward the rear in 96A. On the other hand, when the developing roller 61 is positioned at the spaced position away from the photosensitive drum 50, the first projecting portion 63A is positioned toward the front of the first support surface 96A, like the fourth developing cartridge 60K in FIG. The separating mechanism 5 moves the developing roller 61 from the downstream side to the upstream side in the moving direction of the sheet S when moving the developing roller 61 from the contact position to the separated position.

Returning to FIG. 1 , the conveying device 70 is provided between the sheet tray 21 and the photosensitive drum 50 . The conveying device 70 includes a driving roller 71 , a driven roller 72 , a conveying belt 73 made up of an endless belt, and four transfer rollers 74 . The conveying belt 73 is stretched between the driving roller 71 and the driven roller 72 , and the outer surface of the conveying belt 73 faces the photosensitive drums 50 . Each transfer roller 74 is arranged inside the conveying belt 73 so as to sandwich the conveying belt 73 with each photosensitive drum 50 . The conveying device 70 conveys the sheet S by moving the conveying belt 73 with the sheet S placed on the outer peripheral surface of the upper side.

The fixing device 80 is provided behind the photosensitive drum 50 and the conveying device 70 . The fixing device 80 includes a heating roller 81 and a pressure roller 82 arranged to face the heating roller 81 . A conveying roller 15 is provided above the fixing device 80 , and a discharge roller 16 is provided above the conveying roller 15 .

In the image forming section 30 , first, the surface of each photosensitive drum 50 is uniformly charged by the charger 52 and then exposed to light emitted from the exposure device 40 . As a result, an electrostatic latent image is formed on each photosensitive drum 50 based on the image data.

The toner in the developing cartridge 60 is carried on the surface of the developing roller 61 and supplied to the electrostatic latent image formed on the photosensitive drum 50 when the developing roller 61 faces and contacts the photosensitive drum 50 . . Thereby, a toner image is formed on the photosensitive drum 50 .

Next, the sheet S supplied onto the conveying belt 73 passes between each photosensitive drum 50 and each transfer roller 74, whereby the toner image formed on each photosensitive drum 50 is transferred onto the sheet S. be. As the sheet S passes between the heating roller 81 and the pressure roller 82 , the toner image transferred onto the sheet S is thermally fixed to the sheet S.

The sheet S ejected from the fixing device 80 is accumulated on the paper ejection tray 13 on the upper surface of the housing 10 by the transport roller 15 and the ejection roller 16 .

As shown in FIGS. 6A and 6B, the cam 150 is a member that rotates to move the corresponding developing roller 61 between the contact position and the separated position. The cam 150 has a disc portion 151 , a first gear portion 150 G, a first cam portion 152 , a second cam portion 153 and a phase detection wall 154 .

The disc portion 151 has a substantially disc shape and is rotatably supported by the support plate 102 (see FIG. 9). The disk portion 151 has one positioning hole 159 that penetrates in the axial direction. When each cam 150 is supported by the support plate 102, the positioning hole 159 allows each cam 150 to be assembled in a predetermined phase by inserting a pin provided in an assembly jig (not shown). holes for ease of use. The assembly jig has four pins, and by inserting each pin into the positioning hole 159 of each cam 150, each cam 150 is oriented in a predetermined design direction.
The first gear portion 150G is formed on the outer circumference of the disc portion 151 .

The first cam portion 152 is an end face cam for moving the developing roller 61, and protrudes from the first surface 151A, which is one surface of the disk portion 151, in the direction of the rotation axis. The first cam portion 152 has a shape extending in a circumferential direction around the rotational axis of the cam 150 . The first cam portion 152 has a cam surface 152F on its end face in the rotation axis direction.

The cam surface 152</b>F is a surface for guiding the cam follower 170 between the standby position and the projecting position, and is capable of contacting the cam follower 170 . The cam surface 152F has a first holding surface F1, a second holding surface F2, a first guide surface F3, and a second guide surface F4. The first holding surface F1 holds the cam follower 170 at the standby position. The second holding surface F2 holds the cam follower 170 at the projecting position. The first guide surface F3 is a surface that connects the first holding surface F1 and the second holding surface F2 and is inclined with respect to the first holding surface F1. The second guide surface F4 is a surface that connects the second holding surface F2 and the first holding surface F1 and is inclined with respect to the first holding surface F1. In addition, in FIG. 7 and the like, the dot hatch attached to the first cam portion 152 represents the second holding surface F2.

The second cam portion 153 is a portion that operates the clutch 120 in cooperation with a lever 160 to be described later to switch transmission/disengagement of the clutch 120 . The second cam portion 153 is a plate cam that protrudes in the rotation axis direction from the second surface 151B, which is the other surface of the disc portion 151 . The second cam portion 153 protrudes from the side surface of the disk portion 151 opposite to the side surface on which the first cam portion 152 is arranged. The second cam portion 153 extends in an arc shape when viewed from the rotation axis direction. The second cam portion 153 is formed integrally with the disc portion 151 . Therefore, the second cam portion 153 rotates together with the first cam portion 152 .

The phase detection wall 154 is a wall that extends in the circumferential direction around the rotation axis of the cam 150 and blocks the light emitted by the light emitting elements of the separation sensors 4C and 4K (see FIG. 9). The phase detection wall 154 axially protrudes from the first surface 151A of the disc portion 151 at a position closer to the center of rotation than the first cam portion 152 is. In other words, the phase detection wall 154 protrudes from the same side surface of the disc portion 151 as the side surface on which the first cam portion 152 is arranged. The phase detection wall 154 is arranged inside the inner peripheral surface 152</b>S of the first cam portion 152 . The phase detection wall 154 has a first slit 154A and a second slit 154B for indicating the phase of the cam 150 in the rotational direction.

The first slit 154A allows passage of light emitted by the light emitting elements of the separation sensors 4C and 4K when the developing roller 61 is at the separation position. The second slit 154B transmits light emitted by the light emitting elements of the separation sensors 4C and 4K when the developing roller 61 is in the contact position. The second slit 154B differs from the first slit 154A in size in the circumferential direction. Specifically, the size of the second slit 154B in the circumferential direction is larger than the size of the first slit 154A in the circumferential direction. The first slit 154A and the second slit 154B are located approximately on opposite sides of the rotation axis of the cam 150 .

As shown in FIG. 7 , the cam follower 170 has a slide shaft portion 171 , a contact portion 172 and a spring hook portion 174 .
The slide shaft portion 171 is slidably supported by a support shaft 179 (see FIG. 4) fixed to the housing 10 . The slide shaft portion 171 is slidable in the rotation axis direction.

The contact portion 172 is provided to extend from the slide shaft portion 171 . The end surface of the contact portion 172 in the rotation axis direction faces the cam surface 152F of the first cam portion 152 and can come into contact with the cam surface 152F.
The spring hook portion 174 extends away from the slide shaft portion 171 . In this embodiment, the spring hook portion 174 extends forward as an example.

The first spring 176 is a tension spring. One end of the first spring 176 is hooked on the spring hook portion 174 . The other end of the first spring 176 is hooked on the support plate 102 at a position below the spring hook portion 174 . As a result, the first spring 176 biases the cam follower 170 toward the support plate 102, that is, from the projecting position to the standby position.

As shown in FIG. 9, the cams 150Y, 150M, 150C, and 150K differ from each other in that only the cam 150Y has a longer length in the rotation direction of the cam 150 of the first cam portion 152 than the others. are approximately the same.

The housing 10 is provided with separation sensors 4C and 4K corresponding to black and cyan. The separation sensors 4C and 4K are phase sensors capable of detecting the phases of the cams 150C and 150K. The separation sensors 4C and 4K are composed of photointerrupters having light emitting elements and light receiving elements. As an example, the separation sensors 4C and 4K are configured such that the first slit 154A or the second slit 154B is positioned between the light emitting element and the light receiving element, and when the light receiving element receives the light emitted by the light emitting element, the control unit 2 A signal is output, the phase detection wall 154 enters between the light emitting element and the light receiving element to block the light emitted by the light emitting element, and no signal is output to the control section 2 when the light receiving element does not receive the light.

Light emitted by the light emitting elements of the separation sensors 4C and 4K passes through the first slit 154A and the second slit 154B when the developing roller 61 is at the separation position and the contact position, respectively. Therefore, the separation sensors 4C and 4K output a signal to the control unit 2 when the developing rollers 61 are in the separated position and the light emitted by the light emitting element passes through the first slit 154A and is received by the light receiving element. Further, the separation sensors 4C and 4K output a signal to the control section 2 when each developing roller 61 is in the contact position and the light emitted by the light emitting element passes through the second slit 154B and is received by the light receiving element. In other words, the separation sensors 4C and 4K can detect the first slit 154A when the developing roller 61 is in the separated position, and can detect the second slit 154B when the developing roller 61 is in the contact position. Provided in a detectable position.

The cams 150Y and 150M are also provided with the same shape as the phase detection wall 154, but the separation sensors corresponding to the cams 150Y and 150M are not provided.

Next, details of a configuration for driving/stopping the developing roller 61 and a configuration for moving the developing roller 61 into contact with/separate from the photosensitive drum 50 will be described.
As shown in FIG. 8 , the image forming apparatus 1 includes a motor 3 that drives the developing roller 61 and a drive transmission mechanism 100 that transmits driving force from the motor 3 to the developing roller 61 . The cam 150 described above is mechanically connected to the drive transmission mechanism 100 . The drive transmission mechanism 100 is configured not to transmit the driving force to the developing roller 61 when the developing roller 61 is at the separated position.

Motor 3 is a drive source that drives developing roller 61 and cam 150 . The motor 3 is capable of forward rotation and reverse rotation opposite to the forward rotation, and the rotation is controlled by the controller 2 .

The drive transmission mechanism 100 includes a drive transmission gear train 100D for transmitting the driving force of the motor 3 to the developing roller 61, and a drive control gear train 100C for controlling transmission of the driving force of the drive transmission gear train 100D. are mechanically connected to The drive control gear train 100C can transmit the driving force from the motor 3 to each cam 150, rotates the cam 150 forward when the motor 3 rotates forward, and rotates the cam 150 in reverse when the motor 3 rotates backward. rotate. In FIGS. 8 and 9, meshing between the gears of the drive transmission gear train 100D is indicated by thick solid lines, and meshing between the gears of the drive control gear train 100C is shown by thick dashed lines.

The drive transmission gear train 100D includes two first idle gears 110 (110A, 110B), three second idle gears 113A, 113B, 113C, a third idle gear 115 (115Y, 115M, 115C, 115K), It includes four clutches 120 and four coupling gears 117 (117Y, 117M, 117C, 117K). Each gear constituting the drive transmission gear train 100</b>D is supported by the support plate 102 or a frame (not shown) and is rotatable around a rotation axis parallel to the axial direction of the photosensitive drum 50 .

The motor 3 has a rotationally driven output shaft 3A. A gear (not shown) is provided on the output shaft 3A.

The third idle gears 115Y, 115M, 115C, and 115K are provided corresponding to each color and arranged in this order from front to back.

The four clutches 120 each have the same configuration. Each clutch 120 meshes with one of third idle gears 115Y, 115M, 115C, and 115K and receives driving force from third idle gear 115. As shown in FIG. The configuration of clutch 120 will be described later.

Each coupling gear 117 meshes with one of the clutches 120 . Each coupling gear 117 has a coaxial coupling shaft 119 (see FIG. 9) that rotates together. The coupling shaft 119 is configured to be axially movable in conjunction with the opening and closing of the cover 11 . Specifically, the coupling shaft 119 engages with the coupling 65 (see FIG. 3A) of the developing cartridge 60 when the cover 11 is closed, and is disengaged from the coupling 65 when the cover 11 is opened.

With such drive transmission gear train 100D, yellow coupling gear 117Y receives driving force from motor 3 via first idle gear 110A, second idle gear 113A, third idle gear 115Y and clutch 120. . Driving force is transmitted from the motor 3 to the magenta coupling gear 117M via the first idle gear 110A, the second idle gear 113A, the third idle gear 115M and the clutch 120. FIG. Driving force is transmitted from the motor 3 to the cyan coupling gear 117C via the first idle gear 110B, the second idle gear 113B, the third idle gear 115C and the clutch 120. As shown in FIG. Further, the black coupling gear 117K receives driving force from the motor 3 through the first idle gear 110B, the second idle gear 113B, the third idle gear 115C, the second idle gear 113C, the third idle gear 115K and the clutch 120. is transmitted.

As shown in FIG. 9, the drive control gear train 100C includes two fourth idle gears 131 (131A, 131B), two fifth idle gears 132 (132A, 132B), a YMC electromagnetic clutch 140A and a K electromagnetic clutch. 140K, two sixth idle gears 133 (133A, 133B), a seventh idle gear 134, an eighth idle gear 135, a ninth idle gear 136, a tenth idle gear 137, a cam 150 (150Y, 150M, 150C, 150K). Each gear constituting the drive control gear train 100</b>C is supported by the support plate 102 or a frame (not shown) and is rotatable around a rotation axis parallel to the axial direction of the photosensitive drum 50 .

The two fifth idle gears 132 include a fifth idle gear 132A arranged on the front side of the fourth idle gear 131A and a fifth idle gear 132B arranged on the rear side of the fourth idle gear 131B. Each of the fifth idle gears 132A, 132B meshes with the fourth idle gears 131A, 131B.

The YMC electromagnetic clutch 140A switches transmission/disconnection of the driving force of the drive control gear train 100C of the series that transmits the driving force to the cams 150 of yellow, magenta and cyan. That is, the YMC electromagnetic clutch 140A can switch rotation/stop of the cams 150Y, 150M, and 150C. The YMC electromagnetic clutch 140A includes a large-diameter gear 140L and a small-diameter gear 140S having fewer teeth than the large-diameter gear 140L. The YMC electromagnetic clutch 140A is arranged in front of the fifth idle gear 132A, and the large diameter gear 140L meshes with the fifth idle gear 132A. When the YMC electromagnetic clutch 140A is energized (turned ON), the large-diameter gear 140L and the small-diameter gear 140S rotate together. Gear 140S does not rotate.

The K electromagnetic clutch 140K has the same configuration as the YMC electromagnetic clutch 140A. The K electromagnetic clutch 140K switches transmission/disconnection of the driving force of the drive control gear train 100C of the system that transmits the driving force to the cam 150 of black. The K electromagnetic clutch 140K includes a large-diameter gear 140L and a small-diameter gear 140S having fewer teeth than the large-diameter gear 140L. The K electromagnetic clutch 140K is arranged behind the fifth idle gear 132B, and the large diameter gear 140L meshes with the fifth idle gear 132B.

The two sixth idle gears 133 include a sixth idle gear 133A arranged on the front side of the YMC electromagnetic clutch 140A and a sixth idle gear 133B arranged on the rear side of the K electromagnetic clutch 140K. Each sixth idle gear 133 meshes with the small diameter gear 140S of the YMC electromagnetic clutch 140A or the K electromagnetic clutch 140K.

The seventh idle gear 134 is arranged between the sixth idle gear 133A and the cam 150Y. The seventh idle gear 134 meshes with the sixth idle gear 133A and the first gear portion 150G of the cam 150Y.

The eighth idle gear 135 is arranged between the cam 150Y and the cam 150M. The eighth idle gear 135 meshes with the first gear portion 150G of the cam 150Y and the first gear portion 150G of the cam 150M.

The ninth idle gear 136 is arranged between the cam 150M and the cam 150C. The ninth idle gear 136 meshes with the first gear portion 150G of the cam 150M and the first gear portion 150G of the cam 150C.

The tenth idle gear 137 is arranged between the sixth idle gear 133B and the cam 150K. The tenth idle gear 137 meshes with the sixth idle gear 133B and the first gear portion 150G of the cam 150K.

With such drive control gear train 100C, cam 150Y for yellow is driven from motor 3 to first idle gear 110A, fourth idle gear 131A, fifth idle gear 132A, YMC electromagnetic clutch 140A, sixth idle gear 133A and third idle gear 133A. A driving force is transmitted through the 7 idle gear 134 . Further, the magenta cam 150</b>M receives driving force from the yellow cam 150</b>Y through the eighth idle gear 135 . Further, the cyan cam 150</b>C receives driving force from the magenta cam 150</b>M through the ninth idle gear 136 . By energizing the YMC electromagnetic clutch 140A, the cams 150Y, 150M, 150C rotate simultaneously, and by deenergizing the YMC electromagnetic clutch 140A, the cams 150Y, 150M, 150C all stop.

On the other hand, the black cam 150K is driven from the motor 3 via the first idle gear 110B, fourth idle gear 131B, fifth idle gear 132B, K electromagnetic clutch 140K, sixth idle gear 133B and tenth idle gear 137. force is transmitted. By energizing the K electromagnetic clutch 140K, the cam 150K rotates, and by deenergizing the K electromagnetic clutch 140K, the cam 150K stops.

Next, the configuration and function of clutch 120 will be described.
As shown in FIGS. 10(a) and 10(b), the clutch 120 has a planetary gear mechanism. The clutch 120 is configured to be switchable between a transmission state in which the driving force from the motor 3 is transmitted to the developing roller 61 and a disconnected state in which the driving force from the motor 3 is not transmitted to the developing roller 61 . Specifically, the clutch 120 includes a sun gear 121 , a ring gear 122 and a carrier 123 that are rotatable about one axis, and a planetary gear 124 supported by the carrier 123 .

The sun gear 121 has a disc portion 121B that rotates integrally with the gear portion 121A, and a plurality of claw portions 121C provided on the outer circumference of the disc portion 121B. The claw portion 121C has a sharp tip, and this sharp tip is inclined in one rotational direction in the circumferential direction.
The ring gear 122 has an inner gear 122A provided on the inner peripheral surface and an input gear 122B provided on the outer peripheral surface.

Carrier 123 has four shafts 123A that rotatably support planetary gear 124 . Further, the carrier 123 is provided with an output gear 123B on its outer peripheral surface.

Four planetary gears 124 are provided, and each of them is rotatably supported by the shaft portion 123A of the carrier 123 . The planetary gear 124 meshes with the gear portion 121 A of the sun gear 121 and also meshes with the inner gear 122 A of the ring gear 122 .

Clutch 120 has input gear 122B in mesh with third idle gear 115 (see FIG. 8), and output gear 123B in mesh with coupling gear 117 (see FIG. 8). In a state in which the sun gear 121 is stopped so as not to rotate, a transmission state is established in which the driving force input to the input gear 122B can be transmitted to the output gear 123B. On the other hand, when the sun gear 121 is rotatable, it is in a disconnected state in which the driving force input to the input gear 122B cannot be transmitted to the output gear 123B. When the driving force is input to the input gear 122B while the clutch 120 is disengaged and the load is applied to the output gear 123B, the output gear 123B does not rotate and the sun gear 121 idles.

As shown in FIG. 9, the drive transmission mechanism 100 further includes a lever 160 that is guided by the second cam portion 153 of the cam 150 to swing. Lever 160 is swingably supported by support shaft 102A fixed to support plate 102 . Note that the levers 160 are provided corresponding to the respective colors of yellow, magenta, cyan, and black.

Lever 160 is a member capable of switching clutch 120 between a transmission state and a disengaged state. The lever 160 cooperates with the cam 150 to engage the sun gear 121, which is one of the elements of the planetary gear mechanism, the ring gear 122, and the carrier 123, so that the sun gear 121 does not rotate. It has a function of restricting, setting the clutch 120 to the transmitting state, disengaging from the sun gear 121, and setting the clutch 120 to the disengaged state. The lever 160 switches the clutch 120 between the transmission state and the disengaged state when the cam 150 rotates forward, and maintains the clutch 120 in the disengaged state when the cam 150 rotates in the reverse direction.

Specifically, the lever 160 has a first lever 161, a second lever 162, and a second spring 163, as shown in FIG. 11(a).
The first lever 161 can swing around the swing axis X2, which is the central axis of the support shaft 102A, and can come into contact with the second cam portion 153. As shown in FIG. The first lever 161 includes a rotation support portion 161A having a hole 161B fitted to the support shaft 102A, a first arm 161C extending from the rotation support portion 161A, and protruding from the rotation support portion 161A on the side opposite to the first arm 161C. and a protrusion 161D.

The second lever 162 can swing around the swing axis X2. Second lever 162 is engageable with sun gear 121 , which is one element of clutch 120 . The second lever 162 is combined with the first lever 161, and as shown in FIGS. 11(b) and 11(c), can also swing relative to the first lever 161 around the swing axis X2. be. Conversely, the first lever 161 is combined with the second lever 162 so as to be able to swing relative to the second lever 162 about the swing axis X2. As shown in FIG. 11(c), the position where the first lever 161 swings against the biasing force of the second spring 163 with respect to the second lever 162 is referred to as the "swing position".

The second lever 162 has a rotation support portion 162A having a hole 162B fitted to the support shaft 102A, a second arm 162C extending from the rotation support portion 162A, a rotation restricting portion 162D, and a spring hook portion 162E. The rotation restricting portion 162D protrudes from the second arm 162C in the direction in which the swing axis X2 extends. As shown in FIG. 11B, the rotation restricting portion 162D restricts the rotation of the second lever 162 in one direction with respect to the first lever 161 by contact with the projection 161D.

The second spring 163 is a torsion spring, and urges the first lever 161 against the second lever 162 in a direction in which the projection 161D comes into contact with the rotation restricting portion 162D. In other words, the second spring 163 rotates the first lever 161 against the second lever 162 by contacting the projection 161D of the first lever 161 with the rotation restricting portion 162D provided on the second lever 162. Bias it against rotation.

The tip of the second arm 162C of the lever 160 extends toward the outer peripheral surface of the disk portion 121B of the sun gear 121 when the first lever 161 and the second lever 162 are combined. As shown in FIG. 7, one end of the third spring 169 is hooked on the spring hook portion 162E. The third spring 169 is a tension spring, and the other end of the third spring 169 is hooked on a spring hook (not shown) of the support plate 102 . As a result, the third spring 169 urges the second lever 162 clockwise in the figure. That is, the third spring 169 urges the second arm 162C of the second lever 162 in a direction to swing toward the outer peripheral surface of the sun gear 121 (disk portion 121B). Second arm 162</b>C engages with claw portion 121</b>C on the outer peripheral surface of sun gear 121 to restrict rotation of sun gear 121 .

The tip of the first arm 161</b>C of the lever 160 can come into contact with the outer peripheral surface of the second cam portion 153 . The lever 160 is guided by the second cam portion 153 to move the clutch 120 to the transmitting position as shown in FIG. 7(a) and the clutch 120 as shown in FIG. 7(b). It is swingable between a non-transmitting position in which it is in a disconnected state. As shown in FIG. 7(a), the lever 160 has a first lever 161 whose tip is separated from the second cam portion 153, and a second lever 162 whose tip is a sun gear 121 which is one element of the planetary gear mechanism. engages with the claw portion 121C of the clutch 120 to bring the clutch 120 into the transmission state. 7B, the tip of the first lever 161 of the lever 160 contacts the second cam portion 153 and is pushed, so that the tip of the second lever 162 moves toward the sun gear 121. As shown in FIG. The clutch 120 is disengaged by detaching from the pawl portion 121C.

Further, as shown in FIG. 12, the lever 160 is in the transmission position where the tip of the second lever 162 is engaged with the pawl portion 121C of the sun gear 121, and the cam 150 rotates counterclockwise in the figure. When the first lever 161 rotates and is pushed by the second cam portion 153 , the first lever 161 swings relative to the second lever 162 against the biasing force of the second spring 163 and swings. located in position. Since the first lever 161 can swing relative to the second lever 162 in this manner, the lever 160 is not subjected to excessive force when the cam 150 is reversely rotated.

The control unit 2 is a device that controls the operation of the image forming apparatus 1 . The control unit 2 has a CPU, a ROM, a RAM, an input/output unit, etc., and executes each process by executing a pre-stored program. The control unit 2 controls the driving of the motor 3, controls the ON/OFF of the electromagnetic clutches 140A and 140K, and controls the operation of the cam 150, thereby driving/stopping the developing roller 61 and controlling the operation of the developing roller. 61 to/from the corresponding photosensitive drum 50 is controlled.

Here, an example of processing of the control unit 2 will be described.
In the image forming apparatus 1, all the developing rollers 61 are positioned at the separated positions in a standby state before executing image formation. At this time, as shown in FIG. 7B, the cam follower 170 is positioned at the protruding position where the contact portion 172 contacts the second holding surface F2 of the cam 150 .

When a print job is input and image formation is to be executed, the control unit 2 rotates the motor 3 in the forward direction, turns on the YMC electromagnetic clutch 140A or the K electromagnetic clutch 140K according to the color of the toner used for image formation, and turns on the cam 150. rotate clockwise in the figure. As a result, the contact portion 172 of the cam follower 170 is guided from the second holding surface F2 to the second guide surface F4, slidably contacted on the second guide surface F4, and as shown in FIG. Contact surface F1. As a result, the cam follower 170 slides from the projecting position to the waiting position by the biasing force of the first spring 176, and the developing roller 61 moves from the separated position to the contact position. After the developing roller 61 has moved to the contact position, the control section 2 turns off the YMC electromagnetic clutch 140A and the K electromagnetic clutch 140K to stop the cam 150 .

When the development by the developing roller 61 is completed, the control section 2 turns ON the YMC electromagnetic clutch 140A and the K electromagnetic clutch 140K, and rotates the cam 150 again clockwise in the figure. As a result, the contact portion 172 is guided from the first holding surface F1 to the first guide surface F3, slides on the first guide surface F3, and moves to the second holding surface F2 as shown in FIG. 7(b). Contact. As a result, the cam follower 170 slides from the standby position to the projected position, and the developing roller 61 moves from the contact position to the separated position. When the developing roller 61 is moved to the separated position, the control section 2 turns off the YMC electromagnetic clutch 140A and the K electromagnetic clutch 140K to stop the cam 150 .

As shown in FIG. 13, the spacing mechanism 5 includes a cam 150 (150Y, 150M, 150C, 150K), a cam follower 170, a sector gear 210, a linear motion member 220, a swing member 230, and a fourth spring 240. is further provided. Sector gear 210 includes YMC sector gear 210A and K sector gear 210K, and swinging member 230 includes YMC swinging member 230A and K swinging member 230K.

As shown in FIG. 14, the sector gears 210 (210A, 210K) are two-stage gears having a sector gear portion 211 and a second gear portion 212, respectively. The sector gear portion 211 has a gear tooth portion 211A and a toothless portion 211B on the outer circumference. The gear tooth portion 211A is a portion of the outer periphery of the sector gear portion 211 in which gear teeth are formed, and the toothless portion 211B is a portion of the outer periphery of the sector gear portion 211 in which no gear teeth are formed. The second gear portion 212 has gear teeth formed on the entire outer periphery.

Sector gear 210 rotates in conjunction with the rotation of cam 150 . Specifically, as shown in FIG. 13, in the YMC sector gear 210A, the second gear portion 212 meshes with the first gear portion 150G of the cam 150M. Thus, the YMC sector gear 210A rotates together with the cams 150Y, 150M, 150C when the cams 150Y, 150M, 150C rotate. Further, when the YMC electromagnetic clutch 140A (see FIG. 9) is turned off and the YMC sector gear 210A rotates, the cams 150Y, 150M and 150C rotate.

The second gear portion 212 of the K sector gear 210K meshes with the first gear portion 150G of the cam 150K. Thus, the K sector gear 210K rotates together with the cam 150K when the cam 150K rotates. Further, when the K electromagnetic clutch 140K (see FIG. 9) is turned off and the K sector gear 210K rotates, the cam 150K rotates.

Returning to FIG. 14, each sector gear 210 (210A, 210K) further has a protrusion 213 as an example of a contact portion. The protrusion 213 has a substantially cylindrical shape and protrudes from the sector gear portion 211 in the rotation axis direction. The protrusion 213 is positioned away from the center of rotation of the sector gear 210 , more specifically, at the peripheral edge of the sector gear 210 when viewed from the direction of the rotation axis. More specifically, the projection 213 is located at a position corresponding to the center of the toothless portion 211B in the circumferential direction in the peripheral portion of the sector gear 210 .

As shown in FIG. 15 , the protrusion 213 can be contacted by a swinging member 230 that linearly moves back and forth together with the linear motion member 220 in a state where the toothless portion 211B faces the linear motion member 220 . That is, the protrusion 213 is provided so as to be positioned on the locus of movement (see the dashed line) when the swinging member 230 linearly moves back and forth with the toothless portion 211B facing the linear motion member 220. ing. The projection 213 of the YMC sector gear 210A can be contacted by the YMC swing member 230A, and the projection 213 of the K sector gear 210K can be contacted by the K swing member 230K.

The linear motion member 220 moves the photosensitive drum 50 between the first position shown in FIGS. 13 and 15 and the second position shown in FIG. 17 in conjunction with the movement of the cover 11 between the closed position and the open position. are supported by the housing 10 so as to move linearly in the front-rear direction, which is the direction in which they are arranged. The first position is the position of the linear motion member 220 when the cover 11 is in the closed position, and the second position is the position of the linear motion member 220 when the cover 11 is in the open position.

The linear motion member 220 is connected to the cover 11 via a link (not shown). When the cover 11 is opened by moving from the closed position to the open position, the linear motion member 220 moves forward from the first position to the second position. Further, when the cover 11 is moved from the open position to the closed position and closed, the linear motion member 220 moves from the second position to the rearward first position.

As shown in FIG. 14 , the direct-acting member 220 has a first facing surface 221 , a rack gear portion 222 and a second facing surface 223 on the surface facing the sector gear portion 211 of the sector gear 210 , specifically the upper surface. have Two sets of the first facing surface 221, the rack gear portion 222 and the second facing surface 223 are provided on the linear motion member 220 corresponding to the YMC sector gear 210A and the K sector gear 210K.

The first opposing surface 221 and the second opposing surface 223 are portions where gear teeth are not formed. In the movement direction from the first position to the second position of the direct-acting member 220, the first opposing surface 221 is positioned downstream of the rack gear portion 222, specifically, on the front side of the rack gear portion 222. 223 is located upstream of the rack gear portion 222 , specifically, on the rear side of the rack gear portion 222 .

The rack gear portion 222 is a portion formed with gear teeth, and can mesh with the gear tooth portion 211A of the sector gear 210 . The rack gear portion 222 is provided between the first opposing surface 221 and the second opposing surface 223 .

The sector gear portion 211 of the sector gear 210 faces the first facing surface 221 of the linear motion member 220 when the linear motion member 220 is at the first position. That is, sector gear 210 has gear tooth portion 211A not meshing with rack gear portion 222 when cover 11 is in the closed position. This allows the sector gear 210 and the cam 150 to rotate when the cover 11 is closed. This makes it possible to rotate the cam 150 to move the developing roller 61 between the contact position and the separated position while the cover 11 is closed.

17, sector gear portion 211 of sector gear 210 faces second facing surface 223 of direct-acting member 220 when direct-acting member 220 is at the second position. That is, the gear tooth portion 211A of the sector gear 210 does not mesh with the rack gear portion 222 even when the cover 11 is in the open position.

Returning to FIG. 14 , the swinging member 230 is supported by the linear motion member 220 and linearly moves in the front-rear direction together with the linear motion member 220 . Also, the swinging member 230 can swing with respect to the direct-acting member 220 . Specifically, the swing member 230 is swingably supported by a support shaft 239 fixed to the linear motion member 220 . The swinging member 230 can swing about an axis extending in the rotation axis direction between a pressing position indicated by a solid line and a retracted position indicated by a virtual line.

The rocking members 230 (230A, 230K) each have a rocking support portion 231 having a hole for fitting the support shaft 239, a contact portion 232, and an arm 233. As shown in FIG.

The contact portion 232 extends from the swing support portion 231 . In this embodiment, as an example, the contact portion 232 extends upward from the swing support portion 231 and protrudes above the upper surface of the linear motion member 220 when the swing member 230 is in the pressing position. The contact portion 232 has an inclined surface 232A inclined with respect to the linear motion direction of the swing member 230 and a pressing surface 232B substantially perpendicular to the linear motion direction of the swing member 230 . In the movement direction from the first position to the second position of the direct-acting member 220, the inclined surface 232A is located downstream of the contact portion 232, specifically, the front side of the contact portion 232, and the pressing surface 232B is located on the contact portion. 232 , specifically behind the contact portion 232 .

The inclined surface 232A approaches the linear motion member 220 from the upstream side toward the downstream side in the movement direction of the linear motion member 220 from the first position to the second position when the swing member 230 is at the pressing position. Inclined. Specifically, the slope 232A is inclined downward from the rear side toward the front side when the swing member 230 is in the pressing position. The slope 232A can contact the projection 213 of the sector gear 210 when the swinging member 230 linearly moves along with the linear motion of the linear motion member 220 from the first position to the second position. Further, the pressing surface 232B can come into contact with the protrusion 213 of the sector gear 210 when the swing member 230 linearly moves along with the linear motion of the linear motion member 220 from the second position to the first position.

The arm 233 extends downward from the swing support portion 231 in a direction different from that of the contact portion 232, which is an example in this embodiment. The arm 233 restricts the counterclockwise swing of the swing member 230 by coming into contact with the swing restricting portion 224 provided on the linear motion member 220 .

The fourth spring 240 is a compression spring. One end of the fourth spring 240 is held by the swing restricting portion 224 of the linear motion member 220 . When the fourth spring 240 is in a compressed state, the other end of the fourth spring 240 contacts the rocking member 230 and biases the rocking member 230 counterclockwise in the drawing. As a result, the fourth spring 240 urges the swing member 230 from the retracted position indicated by the imaginary line toward the pressing position indicated by the solid line.

Next, the operation of the spacing mechanism 5 when opening and closing the cover 11 will be described.
First, the operation of the separation mechanism 5 accompanying the movement of the cover 11 from the closed position to the open position from the state where the developing roller 61 is at the separated position will be described.

When a print job is input and image formation is to be performed, the image forming apparatus 1 rotates the cam 150 for a predetermined time to move the developing roller 61 from the separated position to the contact position, thereby performing development by the developing roller 61 . When the development by the developing roller 61 is completed, the cam 150 is rotated again for a predetermined time to move the developing roller 61 from the contact position to the separated position. When image formation is normally completed, all the developing rollers 61 are at the separated position, and as shown in FIG. be. At this time, sector gear 210 ( 210 A, 210 K) has gear tooth portion 211 A facing first facing surface 221 of direct-acting member 220 .

When the cover 11 is moved from the closed position to the open position while the developing roller 61 is at the separated position, the direct-acting member 220 moves forward from the first position to the second position in conjunction with the movement of the cover 11 . do. At this time, the rack gear portion 222 of the linear motion member 220 meshes with the gear tooth portion 211A of the sector gear 210 to rotate the sector gear 210 clockwise in the drawing, thereby rotating the cam 150 meshing with the sector gear 210 counterclockwise in the drawing. rotate.

As a result, the contact portion 172 of the cam follower 170 is guided from the second holding surface F2 to the first guide surface F3, slides on the first guide surface F3, and moves to the first holding surface F1 as shown in FIG. Contact. As a result, the cam follower 170 slides from the projecting position to the waiting position by the biasing force of the first spring 176, and the developing roller 61 can be moved from the separated position to the contact position.

After the developing roller 61 moves to the contact position, the gear tooth portion 211A and the rack gear portion 222 are disengaged, and the toothless portion 211B faces the rear portion of the rack gear portion 222, thereby stopping the rotation of the sector gear 210 and the cam 150. do. The swinging member 230 (230A, 230K) comes into contact with the projection 213 of the sector gear 210 and swings clockwise in the drawing to retreat to the retracted position. After passing the projection 213, the swinging member 230 swings counterclockwise in the drawing by the biasing force of the fourth spring 240 and returns to the pressing position.

After that, as shown in FIG. 17, when the cover 11 reaches the open position and is completely opened, and the direct-acting member 220 reaches the second position, the toothless portion 211B moves toward the second opposing surface 223 of the direct-acting member 220. It will be in a state of facing.

Next, the operation of the separation mechanism 5 accompanying the movement of the cover 11 from the closed position to the open position from the state where the developing roller 61 is in the contact position will be described.
If the sheet S is jammed in the housing 10 during image formation with the developing roller 61 at the contact position, the controller 2 stops the motor 3 . In this case, as shown in FIG. 15, the cam follower 170 is in the standby position where the contact portion 172 is held by the first holding surface F1 of the cam 150. As shown in FIG. At this time, the sector gear 210 (210A, 210K) faces the first facing surface 221 of the linear motion member 220 at the toothless portion 211B.

When the cover 11 is moved from the closed position to the open position while the developing roller 61 is in the contact position, the direct-acting member 220 moves forward from the first position to the second position in conjunction with the movement of the cover 11 . to move. At this time, since the rack gear portion 222 of the linear motion member 220 faces the toothless portion 211B of the sector gear 210, the rack gear portion 222 does not mesh with the gear tooth portion 211A, and the linear motion member 220 moves from the first position to the second position. move towards

The swinging member 230 (230A, 230K) moves the linear motion member 220 when the linear motion member 220 moves from the first position toward the second position in conjunction with the movement of the cover 11 from the closed position to the open position. 232A of slopes contact the protrusion 213 on the way. As shown in FIG. 16, when the swinging member 230 comes into contact with the protrusion 213, the swinging member 230 swings clockwise in the figure and retreats to the retracted position, thereby preventing the sector gear 210 and the cam 150 from rotating and causing the protrusion 213 to move. pass. The swinging member 230 that has passed the projection 213 returns from the retracted position to the pressing position by the biasing force of the fourth spring 240 .

After that, as shown in FIG. 17, when the cover 11 reaches the open position and is completely opened, and the direct-acting member 220 reaches the second position, the toothless portion 211B moves toward the second opposing surface 223 of the direct-acting member 220. It will be in a state of facing.

In the above case, the cam follower 170 is kept at the standby position where the contact portion 172 is held by the first holding surface F1 because the cam 150 does not rotate, and the developing roller 61 is kept at the contact position. maintained.

Next, the operation of the separating mechanism 5 accompanying the movement of the cover 11 from the open position to the closed position will be described.
As shown in FIG. 17 , when the cover 11 is in the open position and the linear motion member 220 is in the second position, the toothless portion 211B of the sector gear 210 faces the second facing surface 223 of the linear motion member 220 .

In this state, when the cover 11 is moved from the open position to the closed position, the linear motion member 220 moves backward from the second position toward the first position in conjunction with the movement of the cover 11 from the open position to the closed position. Moving. When the linear motion member 220 moves from the second position to the first position, the swing member 230 linearly moves rearward together with the linear motion member 220, and as shown in FIG. 232B contacts the protrusion 213 .

When swinging member 230 comes into contact with projection 213, as shown in FIG. It meshes with the rack gear portion 222 . When the rack gear portion 222 and the gear tooth portion 211A are engaged with each other, the linear motion member 220 rotates the sector gear 210 counterclockwise in the drawing, thereby rotating the cam 150 meshing with the sector gear 210 clockwise in the drawing.

As a result, the contact portion 172 of the cam follower 170 is guided from the first holding surface F1 to the first guide surface F3, slides on the first guide surface F3, and moves to the second holding surface F2 as shown in FIG. Contact. As a result, the cam follower 170 slides from the standby position to the projected position, and the developing roller 61 can be moved from the contact position to the separated position.

As shown in FIG. 21, after the developing roller 61 is moved to the spaced position, the rack gear portion 222 passes through the sector gear portion 211 and the rack gear portion 222 and the gear tooth portion 211A are disengaged. stops rotating. After that, when the cover 11 reaches the closed position and is completely closed, the linear motion member 220 reaches the first position.

According to the present embodiment as described above, when the cover 11 is opened, the developing roller 61 can be placed in the contact position. Specifically, when the cover 11 is opened from the state in which the developing roller 61 is at the separated position, the rack gear portion 222 of the linear motion member 220 meshes with the gear tooth portion 211A of the sector gear 210, and the sector gear 210 and the cam 150 rotate. , the developing roller 61 can be moved from the separated position to the contact position.

When the cover 11 is opened from the contact position of the developing roller 61, the rack gear portion 222 of the linear motion member 220 does not mesh with the gear tooth portion 211A of the sector gear 210, so the sector gear 210 and the cam 150 are not rotated. Instead, the developing roller 61 can be maintained in the contact position. Thus, when the cover 11 is opened from the contact position of the developing roller 61, the sector gear 210, the cam 150, and the developing roller 61 can be prevented from moving unnecessarily.

When the developing roller 61 is at the contact position after the cover 11 is opened, the cam follower 170 is at the standby position, so the cam follower 170 can be removed from the second opening 91A of the side frame 91L of the drawer 90. . As a result, the drawer 90 can be moved with respect to the housing 10 , and the developer cartridge 60 can be attached/detached to/from the drawer 90 pulled out from the housing 10 .

After the developer cartridge 60 is attached to the drawer 90 and the drawer 90 is attached to the housing 10, the cover 11 is closed. can bite. Further closing the cover 11 rotates the sector gear 210 and the cam 150, thereby moving the developing roller 61 from the contact position to the separated position.

On the other hand, when the swinging member 230 comes into contact with the projection 213 of the sector gear 210 when the cover 11 is opened, the swinging member 230 swings and retreats, so that the sector gear 210 is not rotated. It can remain in position.

Further, since the sector gear 210 (210A, 210K) is a two-stage gear having the sector gear portion 211 and the second gear portion 212 that meshes with the first gear portion 150G of the cam 150, the sector gear may be formed on the cam. In comparison, for example, the degree of freedom in arranging the direct-acting member 220 within the housing 10 can be increased. As a result, the degree of freedom in designing the spacing mechanism 5 can be increased. Also, the spacing mechanism 5 can be made smaller than when an idle gear is arranged between the sector gear 210 and the cam 150 .

Although the embodiments have been described above, the present invention is not limited to the above-described embodiments, and can be implemented with appropriate modifications as exemplified below.

For example, the linear motion member 220 may have a function of moving the coupling shaft 119 in the rotational axis direction in conjunction with opening and closing of the cover 11 .

In the above-described embodiment, the spacing mechanism 5 has a structure in which the first gear portion 150G of the cam 150 and the second gear portion 212 of the sector gear 210 are directly meshed. may have one or more idle gears between the cam and the sector gear. Also, in the above embodiment, the cam 150 and the sector gear 210 are separate members, but are not limited to this, and may be an integral member. For example, the sector gear may be formed on the cam.

Further, in the above-described embodiment, the second opening 91A formed in the side frame 91L (side wall) of the drawer 90 is a notch (recess) that opens upward, but the present invention is not limited to this. For example, the second opening may be a through hole formed in the side wall.

Also, in the above embodiment, the first spring 176 as a spring was a tension spring, but it is not limited to this. That is, the spring may be any spring other than the tension spring as long as it can urge the cam follower from the projecting position toward the standby position.

In the above-described embodiment, the spacing mechanism 5 has a configuration in which the cam 150 acts on the developing cartridge 60 via the cam follower 170 to bring the developing roller 61 into contact with or separate from it. However, the configuration is not limited to this. For example, the separating mechanism may have a configuration in which the cam does not include a cam follower, and the cam directly acts on the developing cartridge to bring the developing roller into contact with or separate from it.

Further, in the above-described embodiment, the sun gear 121 was illustrated as one element of the planetary gear mechanism with which the lever 160 engages and disengages, but the present invention is not limited to this. For example, one element of the planetary gear mechanism that the lever engages and disengages from may be a ring gear or a carrier.

In the above embodiment, the clutch 120, the lever 160, and the second cam portion 153 of the cam 150 are used to switch between transmitting and not transmitting the driving force from the motor 3 to the developing roller 61, but the present invention is limited to this. not. For example, the clutch, the lever, and the second cam portion may not be provided, and the driving force may be switched between a state in which the driving force is transmitted to the developing roller by an electromagnetic clutch or the like, and a state in which it is not transmitted, regardless of the rotation of the cam.

Further, in the above embodiment, the photosensitive drum 50 is supported by the housing 10 via the drawer 90, but the present invention is not limited to this. For example, a configuration in which a drawer is not provided and a photosensitive drum is directly supported by a housing may be employed.

Further, in the above-described embodiment, the developer cartridge 60 is attachable to and detachable from the drawer 90, and is supported by the housing 10 via the drawer 90. However, the present invention is not limited to this. For example, the developing cartridge may be detachable from the housing and directly supported by the housing.

Further, in the above embodiment, the image forming apparatus 1 is illustrated as a color printer including a plurality of photosensitive drums 50 and a plurality of developing rollers 61, but is not limited to this. For example, the image forming apparatus may be a monochrome printer having one photosensitive drum and one developing roller. Also, the image forming apparatus is not limited to a printer, and may be, for example, a copier, a multifunction machine, or the like.

Moreover, each element described in the above-described embodiment and modifications may be implemented in any combination.

Reference Signs List 1 image forming apparatus 5 spacing mechanism 10 housing 10A first opening 11 cover 50 photosensitive drum 61 developing roller 150 cam 210 sector gear 211A gear tooth portion 211B toothless portion 220 linear motion member 222 rack gear portion

Claims (8)

a housing having an opening;
a cover movable between a closed position closing the opening and an open position opening the opening;
a photosensitive drum;
a developing roller for supplying toner to the photosensitive drum;
An image forming apparatus comprising a separation mechanism capable of moving the developing roller between a contact position where the developing roller contacts the photosensitive drum and a separation position where the developing roller is separated from the photosensitive drum,
The spacing mechanism is
a rotatable cam for moving the developing roller between the contact position and the separated position;
a sector gear that rotates in conjunction with the rotation of the cam, the sector gear having a gear tooth portion having gear teeth and a toothless portion having no gear teeth;
In conjunction with the movement of the cover between the closed position and the open position, a first position, which is the position when the cover is in the closed position, and a position when the cover is in the open position. a linear motion member that linearly moves between a certain second position, the linear motion member having a rack gear portion that can mesh with the gear tooth portion;
The linear motion member is
When the developing roller moves from the first position to the second position in conjunction with the movement of the cover from the closed position to the open position from the spaced position, the rack gear portion engages the gear teeth. portion to rotate the sector gear and the cam to move the developing roller from the spaced position to the contact position;
When the developing roller moves from the first position to the second position in association with the movement of the cover from the closed position to the open position from the contact position, the rack gear portion is moved to the missing tooth. An image forming apparatus, characterized in that the image forming apparatus moves facing the gear tooth portion without meshing with the gear tooth portion. the spacing mechanism includes a swinging member that can swing with respect to the linear motion member, the swinging member linearly moving together with the linear motion member;
The sector gear has a contacted portion that can be contacted by the oscillating member that linearly moves together with the linear motion member in a state in which the toothless portion faces the linear motion member,
The rocking member is
When the direct-acting member contacts the contacted portion while moving from the first position to the second position in conjunction with the movement of the cover from the closed position to the open position, it swings and retreats. By doing so, the sector gear is not rotated,
When the direct-acting member contacts the contacted portion when moving from the second position to the first position in association with the movement of the cover from the open position to the closed position, the contact portion is pushing to rotate the sector gear, meshing the gear tooth portion and the rack gear portion;
The linear motion member rotates the sector gear and the cam to move the developing roller from the contact position when the rack gear portion and the gear tooth portion are engaged when moving from the second position to the first position. 2. The image forming apparatus according to claim 1, wherein the image forming apparatus is moved to the separated position. a drawer movable through the opening with respect to the housing, the drawer having the photosensitive drum and a side wall supporting the photosensitive drum, the side wall having a second opening;
a developing cartridge having the developing roller and detachable from the drawer;
By rotation of the cam, the separating mechanism moves between a standby position, which is a position when the developing roller is in the contact position, and a projecting position, which is a position when the developing roller is in the separated position. A cam follower that slides along the direction of the axis of rotation of the developing roller, and enters the second opening to press the developing cartridge when it is at the projecting position, and pushes the developing cartridge through the second opening when it is at the waiting position. Equipped with a cam follower that can be pulled out,
When the developing cartridge is pressed by the cam follower that has moved from the standby position to the projecting position, the developing roller moves to the spaced position, and the cam follower that has moved from the projecting position to the standby position moves the developing roller to the separated position. 3. The image forming apparatus according to claim 1, wherein the developing roller is supported by the drawer so that the developing roller moves to the contact position when it is no longer pressed. When the linear motion member is at the first position, the sector gear faces a portion of the linear motion member where no gear teeth are formed, and the gear tooth portion is not meshed with the rack gear portion. The image forming apparatus according to any one of claims 1 to 3. The cam has a disk portion and a first gear portion formed on the outer circumference of the disk portion,
4. The sector gear is a two-stage gear having a sector gear portion having the gear tooth portion and the toothless portion, and a second gear portion meshing with the first gear portion. The image forming apparatus according to any one of . 4. The image forming apparatus according to claim 3, wherein the spacing mechanism further includes a spring that biases the cam follower from the projecting position toward the standby position. The cam is
a first cam portion contactable with the cam follower, the first cam portion guiding the cam follower between the projecting position and the standby position;
a second cam portion that rotates together with the first cam portion;
The image forming device
a clutch capable of switching between a transmission state in which driving force is transmitted to the developing roller and a disconnected state in which driving force is not transmitted to the developing roller;
7. The clutch is further provided with a lever that is guided by the second cam portion and swings, the lever being capable of switching the clutch between the transmission state and the disengagement state. The image forming apparatus according to . The clutch has a planetary gear mechanism,
By being guided by the second cam portion, the lever engages with one element of the planetary gear mechanism to bring the clutch into the transmission state, a transmission position, and the one element of the planetary gear mechanism. 8. The image forming apparatus according to claim 7, wherein the image forming apparatus is capable of swinging between a non-transmitting position in which the clutch is disengaged and the clutch is disengaged.

Images