JP7497570B2 - Image forming device - Google Patents

Description

The present invention relates to an image forming device equipped with a cover that can open and close an opening in the housing.

Conventionally, there is known an image forming device that is configured to move a developing cartridge having a developing roller from a contact position where the developing roller contacts the photosensitive drum to a separation position where the developing roller is separated from the photosensitive drum in conjunction with the opening operation of the front cover (Patent Document 1).

JP 2015-069095 A

In an image forming device, it is desirable for the load applied when opening the cover to be as small as possible.

Therefore, the present invention aims to provide an image forming device that can reduce the load when opening the cover.

In order to achieve the above-mentioned object, the image forming apparatus of the present invention comprises a housing having an opening, a cover movable between a closed position which closes the opening and an open position which opens the opening, a photosensitive drum, a developing cartridge having a developing roller, and a separation mechanism movable between a contact position where the developing roller contacts the photosensitive drum and a separation position where it is separated from the photosensitive drum.
The spacing mechanism includes a cam having a first cam portion, a support shaft provided on the housing, a cam follower that engages with the support shaft and is slidable between a protruding position and a standby position along the axial direction of the support shaft and is rotatable around the axis of the support shaft between an operating position and a non-operating position, the cam follower having a contact portion that can contact the first cam portion and an arm extending in a direction away from the support shaft, and a release member that can move in conjunction with the opening and closing of the cover.
The release member rotates the cam follower from an actuated position to a non-actuated position when the cover moves from the closed position to the open position.
When the cam follower is in the operating position, as the cam rotates, the contact portion is guided by the first cam portion and can slide between the protruding position and the standby position; when in the protruding position, the cam follower presses the developing cartridge to position the developing roller in the separated position, and when in the standby position, the cam follower positions the developing roller in the contact position.
Furthermore, when the cam follower is in the inoperative position, the contact portion is not guided by the first cam portion, and the cam follower is maintained in the standby position regardless of the rotation of the cam.
The cam follower has a pressing surface that presses the developing cartridge.
The developing cartridge has a pressed surface that is pressed by the pressing surface.
The pressing surface is tapered toward the pressed surface.

This configuration reduces the contact area between the pressing surface of the cam follower and the pressed surface of the developer cartridge, so the load required to rotate the cam follower can be reduced. This reduces the load required to open the cover.

In the image forming device described above, the pressing surface can be configured to have a spherical shape.

This allows the load to be reduced when rotating the cam follower.

In the image forming device described above, the cam follower can be configured to engage with the support shaft, slide relative to the support shaft, and have a shaft portion that can rotate around the axis of the support shaft, with the pressing surface being provided at one end of the shaft portion in the axial direction.

This allows the pressing surface and the pressed surface to come into contact approximately on the axis of the shaft, so the force applied from the pressed surface to the pressing surface is less likely to impede the rotation of the cam follower. This makes it possible to further reduce the load when rotating the cam follower.

In the image forming device described above, the surface to be pressed can be configured to have a flat shape.

This allows the contact state between the pressing surface and the pressed surface to be made substantially uniform even if the contact position between the pressing surface and the pressed surface is misaligned. This allows the load to be reduced when rotating the cam follower, regardless of the contact position between the pressing surface and the pressed surface.

In the image forming device described above, the separation mechanism can be configured to include a spring that urges the cam follower from the inoperative position toward the operative position.

This allows the load required to rotate the cam follower to be reduced, so the cam follower can be rotated from the inoperative position to the operative position without increasing the spring force.

In the image forming device described above, the release member has a release engagement portion that contacts the arm to rotate the cam follower from the operating position to the non-operating position when the cover moves from the closed position to the open position, and the release engagement portion can be configured to contact the arm to restrict rotation of the cam follower when the cam rotates in the first rotation direction and the first cam portion guides the contact portion when the cam follower is in the operating position.

The image forming device described above can be configured to include a stopper that is provided so that an arm is positioned between the cam follower and the release engagement portion when the cam is in the operating position, and that contacts the arm to restrict rotation of the cam follower when the cam rotates in a second rotation direction opposite to the first rotation direction and the first cam portion guides the contact portion.

The image forming device described above includes a control unit, and the control unit can be configured to rotate the cam in a second rotation direction when the cover moves from the open position to the closed position, and then rotate the cam in a first rotation direction to bring the arm into contact with the release engagement portion.

This allows the load applied when rotating the cam follower to be reduced, so that the arm can be reliably brought into contact with the release engagement portion when the rotation direction of the cam is switched from the second rotation direction to the first rotation direction. This improves the positional accuracy of the contact portion and the first cam portion after the cover is closed to rotate the cam and then the rotation of the cam is stopped.

In the image forming device described above, the stopper moves together with the release member in conjunction with the opening and closing of the cover, and is capable of swinging relative to the release member. When the cover moves from the open position to the closed position, the cam follower rotates from the inoperative position to the operative position due to the biasing force of the spring, and is pushed by the arm to swing, allowing the cam follower to rotate from the inoperative position to the operative position.

With this, the cam follower can be returned from the inoperative position to the operative position by closing the cover. At this time, the load applied when rotating the cam follower can be reduced, allowing the cam follower to operate smoothly.

This invention reduces the load required to open the cover.

1 is a diagram showing a schematic configuration of an image forming apparatus according to an embodiment; FIG. 2 is a perspective view of a drawer, a cam, and a cam follower. 3A is a perspective view of a developing cartridge, and FIG. 5A is a schematic diagram illustrating a sliding member when the periphery of the developing cartridge is viewed from above, and shows a state in which the cam follower is located at a standby position and a state in which the cam follower is located at a protruding position; FIG. 4 is a diagram showing the inner surface (developer cartridge side) of the side frame of the drawer. FIG. 3A and 3B are perspective views of a cam follower, and FIG. FIG. 4 is a view of the drive transmission mechanism as seen from the left side along the axial direction. FIG. 2 is a perspective view of the drive transmission mechanism as viewed from the upper right. FIG. 4 is a view of the drive transmission mechanism as seen from the right side along the axial direction. 1A is a side view showing the release member when the cover is in a closed position, and FIG. 1B is a side view showing the release member when the cover is in an open position. 5A and 5B are diagrams illustrating the configuration of the stopper, showing (a) the stopper in a first position where it is not pressed by the arm, and (b) the stopper in a second position where it is pressed by the arm and swung. 1A is an exploded perspective view of a clutch as viewed from a sun gear side, and FIG. 1B is an exploded perspective view of a clutch as viewed from a carrier side. 1A is an exploded oblique view of the lever, FIG. 1B is a diagram showing a state in which the rotation of the first lever is restricted by a rotation restricting portion, and FIG. 1C is a diagram showing a state in which the first lever is swung relative to the second lever. 5 is a flowchart showing a process of a control unit when the power is turned on. 13 is a flowchart of a cam reverse rotation and separation process. 4 is a timing chart illustrating the operation of each part after the power is turned on. 1A is a perspective view showing a cam, a cam follower, and a release member when the cam rotates forward and the developing roller is in a contact position, and FIG. 1A is a perspective view showing a cam, a cam follower, and a release member when the cam rotates forward and the developing roller is in a separated position, and FIG. 1A is a perspective view showing a cam, a cam follower, and a release member when the cover is in an open position, and FIG. 20A is a perspective view showing the cam, the cam follower, and the release member when the cover is moved from the open position to the closed position from the state shown in FIG. 19, and FIG. 21A is a side view showing a cam, a cam follower and a release member, in which FIG. 21A shows a state in which the cam has rotated in the reverse direction from the state shown in FIG. 20 and the cam follower has returned from the non-operating position to the operating position, and FIG. 21B shows a state in which the cam has further rotated in the reverse direction and the stopper is regulating the rotation of the cam follower. 21(b) is a side view showing the cam, cam follower and release member, in which FIG. 21(a) shows a state in which the cam has further rotated in the reverse direction from the state shown in FIG. 21(b) so that the developing roller is in the separated position and the first lever is in the swing position, and FIG. 21(b) shows a state in which the cam has further rotated in the reverse direction so that the developing roller is in the contact position. 22(a) is a side view showing the cam, cam follower and release member, in which FIG. 22(a) shows a state in which the cam further rotates in the reverse direction from the state in FIG. 22(b) so that the contact portion contacts the first cam portion and the rotation of the arm is restricted by the stopper, and FIG. 22(b) shows a state in which the sensor has detected the detected portion twice, and then the detected portion has passed the sensor and the cam has stopped. 23(b) is a side view showing the cam, the cam follower and the release member, and shows a state in which the cam rotates forward from the state in FIG. 23(b), the sensor detects the detected portion, and the cam stops. FIG.

As shown in FIG. 1, the image forming device 1 according to the embodiment is a color printer, and mainly comprises a housing 10, a cover 11, a sheet supply unit 20, an image forming unit 30, and a control unit 2. For convenience, in this specification, directions such as front and back will be described with the left side of FIG. 1, where the sheet tray 21 is pulled out, as the front. In other words, the left side of FIG. 1 is the front, the right side is the rear, the top and bottom are the top and bottom, the front side of the paper in FIG. 1 is the right, and the back side of the paper is the left.

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 shown by a solid line in which the first opening 10A is closed, and an open position shown by a virtual line in which the first opening 10A is open. 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 a signal from the cover sensor.

The sheet supply unit 20 is provided at the bottom of the housing 10 and includes a sheet tray 21 that stores sheets S, and a supply mechanism 22 that supplies sheets S from the sheet tray 21 to the image forming unit 30. The sheet tray 21 is configured to be removable by pulling it out from the housing 10 to the left side in FIG. 1. The supply mechanism 22 is provided at the front of the housing 10 and includes a paper feed roller 23, a separation roller 24, a separation pad 25, and a registration roller 27. The sheet S in this specification is a medium on which the image forming device 1 can form an image, and includes plain paper, envelopes, postcards, thin paper, thick paper, glossy paper, resin sheets, stickers, etc.

In the sheet supply unit 20, the sheets S in the sheet tray 21 are sent out by the feed roller 23, and then the sheets S are separated one by one between the separation roller 24 and the separation pad 25. The leading edge position of the sheets S is then regulated by the registration roller 27, which is in a stopped state, and the sheets S are then supplied to the image forming unit 30 by the rotation of the registration roller 27.

The image forming unit 30 includes an exposure device 40, a number of photosensitive drums 50, a number of developing cartridges 60, a conveying device 70, and a fixing unit 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 multiple laser beams that expose the multiple photosensitive drums 50 and scan the surfaces of the photosensitive drums 50.

The photosensitive drum 50 includes a first photosensitive drum 50Y corresponding to yellow, a second photosensitive drum 50M corresponding to magenta, a third photosensitive drum 50C corresponding to cyan, and a fourth photosensitive drum 50K corresponding to black. In this specification and drawings, the members provided for the colors yellow, magenta, cyan, and black are indicated with Y, M, C, and K, respectively, when the colors are to be distinguished. On the other hand, when the description is given without distinguishing the colors, the reference characters Y, M, C, and K are not added, and the names 1st, 2nd, etc. are omitted.

The developing cartridges 60 are provided corresponding to each photosensitive drum 50. Specifically, the developing cartridges 60 include a first developing cartridge 60Y having a first developing roller 61Y that supplies toner to the first photosensitive drum 50Y, a second developing cartridge 60M having a second developing roller 61M that supplies toner to the second photosensitive drum 50M, a third developing cartridge 60C having a third developing roller 61C that supplies toner to the third photosensitive drum 50C, and a fourth developing cartridge 60K having a fourth developing roller 61K that supplies toner to the fourth photosensitive drum 50K.

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 the upstream side to the downstream side in the movement direction of the sheet S.

Each developing cartridge 60 is movable between a contact position shown by a solid line in FIG. 1, where the developing roller 61 contacts the corresponding photosensitive drum 50, and a separation position shown by a virtual line in FIG. 1, where the developing roller 61 is separated from the corresponding photosensitive drum 50.

As shown in FIG. 2, the photosensitive drum 50 is rotatably supported by the drawer 90. The drawer 90 also supports the developing cartridge 60 in a detachable manner. The drawer 90 is detachable from the housing 10 through a first opening 10A formed by opening the cover 11 (see FIG. 1) of the housing 10. The drawer 90 includes a pair of side frames 91 as side walls arranged apart in the axial direction of the photosensitive drum 50, a connecting frame 92 connecting the front parts of the pair of side frames 91, and a connecting frame 93 connecting the rear parts of the pair of side frames 91. The pair of side frames 91 includes a right side frame 91R and a left side frame 91L. The drawer 90 is provided with a charger 52 (see FIG. 1) arranged opposite each photosensitive drum 50 for charging the photosensitive drum 50.

Although detailed structural illustration is omitted, the pair of side frames 91 support the ends of the photosensitive drum 0. One of the side frames 91, in this case the left side frame 91L, has a second opening 91A. The second opening 91A is formed as a downwardly recessed notch on the upper edge of the side frame 91L. As a result, the second opening 91A penetrates the side frame 91L from left to right, allowing the cam follower 170, described below, to enter.

The image forming device 1 includes a separation mechanism 5 that can move the first developing roller 61Y, the second developing roller 61M, the third developing roller 61C, and the fourth developing roller 61K between a contact position where the rollers contact the corresponding photosensitive drums 50 among the multiple photosensitive drums 50, and a separation position where the rollers are separated from the corresponding photosensitive drums 50.

Specifically, the spacing mechanism 5 includes cams 150 (150Y, 150M, 150C, 150K) that rotate 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 spring 176, and a release member 180 (see FIG. 8). In this embodiment, the first spring 176 corresponds to the "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 “rotation axis direction”).

The support shaft 179 is a shaft that extends long to the left and right. The support shaft 179 is provided on a side frame (not shown) of the housing 10.

The cam follower 170 engages with the support shaft 179 and is slidable along the axial direction of the support shaft 179 and rotatable around the axis of the support shaft 179. The cam follower 170 has a contact portion 172 that can contact the first cam portion 152. Specifically, the cam follower 170 can rotate between an operating position shown in Figures 18(a) and (b) in which the contact portion 172 can contact the end face of the first cam portion 152, and a non-operating position shown in Figures 19(a) and (b) in which the contact portion 172 cannot contact the end face of the first cam portion 152. In the non-operating position, the cam follower 170 is disposed at a position that does not overlap with the first cam portion 152 when viewed from the direction of the rotation axis. Furthermore, when the cam follower 170 is in the operating position, it contacts the cam surface 152F, which is the end face of the first cam portion 152 of the cam 150. As the cam 150 rotates, the contact portion 172 is guided by the first cam portion 152 and can slide between the protruding position shown in FIG. 4(b), which positions the developing roller 61 in the separated position, and the standby position shown in FIG. 4(a), which positions the developing roller 61 in the contact position.

When the cam follower 170 is in the protruding position, it enters the second opening 91A and presses the developer cartridge 60 to position the developer roller 61 in the separated position, and when it is in the standby position, it exits the second opening 91A and positions the developer roller 61 in the contact position. On the other hand, when the cam follower 170 is in the inoperative position due to the movement of the release member 180 accompanying the movement of the cover 11 from the open position to the closed position, the contact portion 172 is not guided by the first cam portion 152 and is maintained in the standby position regardless of the rotation of the cam 150.

Returning to FIG. 2, the cam 150 and cam follower 170 are provided for each developing cartridge 60. The cam 150 and cam follower 170 are disposed on the outer side in the left-right direction of the left side frame 91L. The detailed structures of the cam 150, cam follower 170, and release member 180 will be described later.

The drawer 90 has contact portions 94 at the top of the side frames 91R and 91L that contact the slide members 64 described below. The contact portions 94 are, for example, rollers that can rotate around an axis along a third direction (vertical direction) that is perpendicular to both a first direction parallel to the axial direction of the photosensitive drums 50 and a second direction in which the photosensitive drums 50 are arranged.

The drawer 90 also includes a pressing member 95 provided for each developer cartridge 60. The pressing member 95 is provided for each developer cartridge 60 at both axial ends of the photosensitive drum 50. The pressing member 95 is biased rearward by a spring 95A (see Figures 4(a) and (b)). When the developer cartridge 60 is attached to the drawer 90, the pressing member 95 presses the protrusion 63D of the developer cartridge 60 to bring the developer roller 61 into contact with the corresponding photosensitive drum 50.

As shown in Figures 3(a) and (b), the developing cartridge 60 has a case 63 that contains toner, a sliding member 64, and a coupling 65.

The case 63 has a first protrusion 63A and a second protrusion 63B on one side as protrusions that protrude in the direction of the rotation axis. 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 protrusion 63B is arranged a predetermined distance away from the first protrusion 63A. In this embodiment, the second protrusion 63B is arranged above the first protrusion 63A. Both the first protrusion 63A and the second protrusion 63B are rollers that can rotate around an axis that is parallel to the direction of the rotation axis. Although not shown, the case 63 also has a first protrusion 63A and a second protrusion 63B on the other side at a position symmetrical to the one side.

In addition, the case 63 has a protrusion 63D at the upper front portion of the side surface that is pressed by the pressing member 95. The protrusions 63D are provided at both ends of the case 63 in the direction of the rotation axis.

The coupling 65 engages with a coupling shaft 119 (see FIG. 8) described below, and receives a rotational driving force from the coupling shaft 119.

The slide member 64 is a member that can slide in the direction of the rotation axis relative to the case 63. The slide member 64 can slide in the direction of the rotation axis by being pressed by the cam follower 170.

As shown in Figures 4(a) and (b), the slide member 64 includes a shaft 191, a first abutment member 192, and a second abutment member 193. The first abutment member 192 is fixed to one end of the shaft 191, and the second abutment 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 that extends in the direction of the rotation axis, and is supported in the case 63 so that it can slide.

The first contact member 192 has a pressed surface 192A which is an end surface in the rotation axis direction, and an inclined surface 192B which is inclined with respect to the rotation axis direction.
The pressed surface 192A is a surface that is pressed by a pressing surface 175 (described later) of the cam follower 170. The pressed surface 192A has a planar shape. More specifically, the pressed surface 192A has a planar shape that is approximately perpendicular to the rotation axis direction.

When the slide member 64 is pressed in the direction of the rotation axis by the cam follower 170, the inclined surface 192B comes into contact with the contact portion 94 of the drawer 90, urging the developer cartridge 60 in a direction parallel to the moving direction of the sheet S, and moving the developer cartridge 60 (see FIG. 4B). As the inclined surface 192B moves from one end of the shaft 191 to the other end, it is inclined so as to be positioned in the direction (forward) from the photosensitive drum 50 toward the corresponding developer roller 61 in the second direction.

The second contact member 193 has an inclined surface 193B that is inclined similarly to the inclined surface 192B of the first contact member 192. When the slide member 64 is pressed in the direction of the rotation axis by the cam follower 170, the inclined surface 193B also comes into contact with the contacted portion 94 of the drawer 90, and urges the developer cartridge 60 in a direction parallel to the moving direction of the sheet S, thereby moving the developer cartridge 60 (see FIG. 4B).

A fourth spring 194 is disposed between the first contact member 192 and the case 63, which biases the slide member 64 in one direction along the rotation axis, in this case, toward the left side. The fourth spring 194 is a compression coil spring, and is disposed outside the shaft 191 so that the shaft 191 passes through the coil.

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 of the side frames 91L. The first support surface 96A and the second support surface 96B support the first protrusion 63A and the second protrusion 63B from below, respectively, when the developing roller 61 moves from the contact position to the separation position. The first support surface 96A and the second support surface 96B extend in the movement direction of the sheet S. The first support surface 96A is arranged to support the first protrusion 63A. The first support surface 96A serves both to guide the developing roller 61 when the developing cartridge 60 is attached to the drawer 90 and to position it in the up-down direction. The second support surface 96B is arranged above the first support surface 96A to support the second protrusion 63B. Although not shown in the figure, 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 symmetrical to the first side frame 91L.

When the developing roller 61 is located at a contact position where it contacts the photosensitive drum 50, the first protruding portion 63A is located toward the rear of the first support surface 96A as in the first developing cartridge 60Y, the second developing cartridge 60M, and the third developing cartridge 60C in Fig. 5. On the other hand, when the developing roller 61 is located at a separated position where it is separated from the photosensitive drum 50, the first protruding portion 63A is located toward the front of the first support surface 96A as in the fourth developing cartridge 60K in Fig. 5.
In this manner, when the separating mechanism 5 moves the developing roller 61 from the contact position to the separated position, 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.

As shown in Figures 17(a) and (b), the cam 150 has a disk portion 151, a gear portion 150G, a first cam portion 152, a second cam portion 153, and a detected portion 154. The cam 150 is a member that moves the corresponding developing roller 61 between a contact position and a separated position by rotating.

The disk portion 151 has a generally disk shape, and is rotatably supported by the support plate 102 (see FIG. 8).
The gear portion 150G is formed on the outer periphery of the disk portion 151 .
The first cam portion 152 is a portion that protrudes from the disk portion 151 and constitutes the separating mechanism 5 for the developing roller 61. The first cam portion 152 has a cam surface 152F on an end surface in the rotational axis direction.

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 in a standby position. The second holding surface F2 holds the cam follower 170 in a protruding 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. Note that in FIG. 11 and FIG. 17 to FIG. 24, the dot hatching on the first cam portion 152 represents the second holding surface F2.

The second cam portion 153 cooperates with the lever 160 to switch between transmission and disconnection of the clutch 120. The second cam portion 153 protrudes from the disk portion 151 in the direction of the rotation axis. The second cam portion 153 protrudes from one side of the disk portion 151 opposite the side on which the first cam portion 152 is arranged. The second cam portion 153 extends in an arc shape when viewed from the direction of the rotation axis. The second cam portion 153 is formed integrally with the disk portion 151. Therefore, the second cam portion 153 rotates together with the first cam portion 152.

The detected portion 154 protrudes in the axial direction from the disk portion 151 at a position closer to the center of rotation than the first cam portion 152. The detected portion 154 is a portion that indicates the phase of the rotational direction of the cam 150, and is detected by the separation sensors 4C and 4K described below.

The cam follower 170 has a shaft portion 171 , a contact portion 172 , an arm 173 , a spring hook portion 174 , and a pressing surface 175 .
The shaft portion 171 is cylindrical with a bottom (see FIG. 6 ), engages with a support shaft 179 fixed to the housing 10, and is supported by the support shaft 179 so as to be slidable. This allows the shaft portion 171 to slide in the direction of the rotation axis relative to the support shaft 179. The shaft portion 171 is also supported by the support shaft 179 so as to be rotatable. This allows the shaft portion 171 to rotate around the axis of the support shaft 179.

The contact portion 172 is provided extending from the shaft portion 171. An end face of the contact portion 172 in the rotation axis direction faces the cam surface 152F of the first cam portion 152 and is capable of coming into contact with the cam surface 152F.
The arm 173 extends in a direction away from the support shaft 179 and the shaft portion 171. The arm 173 extends from the shaft portion 171 in a direction different from that of the contact portion 172, for example, downward in this embodiment.
The spring hook portion 174 extends in a direction away from the shaft portion 171. In the present embodiment, the spring hook portion 174 extends forward, for example.

The first spring 176 is a tension spring. One end of the first spring 176 is hooked to the spring hook portion 174. The other end of the first spring 176 is hooked to a position on the support plate 102 that is lower than 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 protruding position toward the standby position. The first spring 176 also biases the cam follower 170 counterclockwise in FIGS. 17(a) and (b), that is, from the non-operating position toward the operating position.

As shown in Figures 6(a) to (c), the pressing surface 175 is a surface that presses the pressed surface 192A of the developing cartridge 60, and is provided at one end of the shaft portion 171 in the axial direction of the support shaft 179. The pressing surface 175 has a shape that tapers toward the pressed surface 192A of the developing cartridge 60. Specifically, the pressing surface 175 has a spherical shape that is convex toward the pressed surface 192A.

8, the cams 150Y, 150M, and 150C are substantially the same in configuration except that the length of the first cam portion 152 of the cam 150Y is longer than the others in the rotational direction of the cam 150. The black cam 150K is provided with two first cam portions 152 that are short in the rotational direction.
The housing 10 is provided with separation sensors 4C and 4K corresponding to cyan and black. The separation sensors 4C and 4K are phase sensors capable of detecting the origin of the phase of the cams 150C and 150K. The separation sensors 4C and 4K output a separation signal when the cams 150C and 150K are located in a predetermined phase range in which the third developing roller 61C and the fourth developing roller 61K are in the separated position, and do not output a separation signal when the cams 150C and 150K are not located in the predetermined phase range. In this embodiment, for convenience, the case where the separation signal is output is called ON, and the case where the separation signal is not output is called OFF. It does not matter which voltage is higher when the separation signal is output or not output.

The separation sensors 4C and 4K have a light-emitting portion that emits detection light and a light-receiving portion that can receive the detection light from the light-emitting portion. The separation sensors 4C and 4K output an ON signal to the control unit 2 when the detected portion 154 comes between the light-emitting portion and the light-receiving portion, blocking the detection light from the light-emitting portion, and the light-receiving portion does not receive the detection light, and output an OFF signal to the control unit 2 when the detected portion 154 comes out from between the light-emitting portion and the light-receiving portion and the light-receiving portion receives the detection light from the light-emitting portion. The cams 150Y and 150M are also provided with a shape similar to the detected portion 154, but since there is no separation sensor corresponding to the cams 150Y and 150M, these do not function as detected portions.

Returning to FIG. 1, the conveying device 70 is provided between the sheet tray 21 and the photosensitive drums 50. The conveying device 70 includes a drive roller 71, a driven roller 72, a conveying belt 73 consisting of an endless belt, and four transfer rollers 74. The conveying belt 73 is stretched between the drive roller 71 and the driven roller 72, and its outer surface is arranged to face each photosensitive drum 50. Each transfer roller 74 is arranged inside the conveying belt 73 so as to sandwich the conveying belt 73 between 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 upper outer peripheral surface, and at this time, transfers the toner images of the multiple photosensitive drums 50 to the sheet S.

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

In the image forming unit 30 configured in this manner, the surface of each photosensitive drum 50 is first uniformly charged by the charger 52, and then exposed to light emitted from the exposure device 40. This forms an electrostatic latent image based on image data on each photosensitive drum 50.

The toner in the case 63 is carried on the surface of the developing roller 61, and when the developing roller 61 comes into contact with the photosensitive drum 50, the toner is supplied to the electrostatic latent image formed on the photosensitive drum 50. This forms a toner image on the photosensitive drum 50.

Next, the sheet S fed onto the conveyor belt 73 passes between each photosensitive drum 50 and each transfer roller 74, so that the toner image formed on each photosensitive drum 50 is transferred onto the sheet S. Then, the sheet S passes between the heating roller 81 and the pressure roller 82, so that the toner image transferred onto the sheet S is thermally fixed onto the sheet S.

The sheet S discharged from the fixing unit 80 is accumulated in the discharge tray 13 on the top surface of the housing 10 by the conveying rollers 15 and the discharge rollers 16.

Next, a configuration for driving and stopping the developing roller 61 and a configuration for moving the developing roller 61 so as to contact and separate from the photosensitive drum 50 will be described in detail.
7, the image forming apparatus 1 includes a motor 3 that drives the developing roller 61, and a drive transmission mechanism 100 that transmits a drive force from the motor 3 to the developing roller 61. The cam 150 that is a part of the separation mechanism 5 described above is mechanically connected to the drive transmission mechanism 100. The drive transmission mechanism 100 is configured not to transmit a drive force to the developing roller 61 when the developing roller 61 is in the separation position.

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 is mechanically connected to a drive control gear train 100C for controlling the transmission of the driving force of the drive transmission gear train 100D. In Figures 7 and 9, the meshing of the gears in the drive transmission gear train 100D is indicated by thick solid lines, and the meshing of the gears in the drive control gear train 100C is indicated 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), four clutches 120, and four coupling gears 117 (117Y, 117M, 117C, 117K). Each gear constituting the drive transmission gear train 100D is supported by a support plate 102 or a frame (not shown) and can rotate around a rotation axis parallel to the axial direction of the photosensitive drum 50.

The motor 3 has an output shaft 3A that rotates. The output shaft 3A is provided with a gear (not shown).

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

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

Each coupling gear 117 meshes with one of the clutches 120. Each coupling gear 117 has a coupling shaft 119 (see FIG. 8) that rotates coaxially with the coupling gear 117. The coupling shaft 119 is configured to be movable axially in conjunction with the opening and closing of the cover 11, and engages with the coupling 65 (see FIG. 3(a)) of the developing cartridge 60 when the cover 11 is closed.

By means of this drive transmission gear train 100D, the drive force is transmitted from the motor 3 to the yellow coupling gear 117Y via the first idle gear 110A, the second idle gear 113A, the third idle gear 115Y and the clutch 120.
Further, the 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.
Further, 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.
Further, the driving force is transmitted from the motor 3 to the black coupling gear 117K via 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.

As shown in Figures 8 and 9, the drive control gear train 100C includes two fourth idle gears 131 (131A, 131B), two fifth idle gears 132 (132A, 132B), a YMC clutch 140A and a K 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, and a cam 150 (150Y, 150M, 150C, 150K). Each gear constituting the drive control gear train 100C is supported by a support plate 102 or a frame (not shown) and can rotate 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 disposed in front of the fourth idle gear 131A, and a fifth idle gear 132B disposed behind the fourth idle gear 131B. Each of the fifth idle gears 132A, 132B meshes with the fourth idle gears 131A, 131B.

The YMC clutch 140A switches between transmitting and disconnecting the driving force of the drive control gear train 100C, which transmits driving force to the yellow, magenta, and cyan cams 150. In other words, the YMC clutch 140A can switch between rotating and stopping the cams 150Y, 150M, and 150C. The YMC 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 clutch 140A is disposed in front of the fifth idle gear 132A, and the large diameter gear 140L meshes with the fifth idle gear 132A.
The YMC clutch 140A is, for example, an electromagnetic clutch. When electricity is applied (ON), the large diameter gear 140L and the small diameter gear 140S rotate together. When electricity is stopped (OFF), the large diameter gear 140L rotates freely and the small diameter gear 140S does not rotate.

The K clutch 140K has the same configuration as the YMC clutch 140A. The K clutch 140K switches between transmitting and disconnecting the driving force of the drive control gear train 100C, which transmits driving force to the black cam 150. The K clutch 140K includes a large diameter gear 140L and a small diameter gear 140S that has fewer teeth than the large diameter gear 140L. The K clutch 140K is disposed 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 disposed in front of the YMC clutch 140A and a sixth idle gear 133B disposed in rear of the K clutch 140K. Each sixth idle gear 133 meshes with the small diameter gear 140S of the YMC clutch 140A or the K clutch 140K.

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

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

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

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

With this type of drive control gear train 100C, driving force is transmitted from the motor 3 to the yellow cam 150Y via the first idle gear 110A, the fourth idle gear 131A, the fifth idle gear 132A, the YMC clutch 140A, the sixth idle gear 133A and the seventh idle gear 134.
Further, the driving force is transmitted to the magenta cam 150M from the yellow cam 150Y via the eighth idle gear 135.
Further, the driving force is transmitted to the cyan cam 150C from the magenta cam 150M via the ninth idle gear 136.
When the YMC clutch 140A is energized, the cams 150Y, 150M, and 150C rotate simultaneously, and when the YMC clutch 140A is deenergized, the cams 150Y, 150M, and 150C all stop.

On the other hand, the driving force is transmitted from the motor 3 to the black cam 150K via the first idle gear 110B, the fourth idle gear 131B, the fifth idle gear 132B, the K clutch 140K, the sixth idle gear 133B and the tenth idle gear 137.
When the K-clutch 140K is energized, the cam 150K rotates, and when the K-clutch 140K is deenergized, the cam 150K stops.

Next, the release member 180 will be described.
The release member 180 is a member that moves the coupling shaft 119 in the direction of the rotation axis and rotates the cam follower 170 from the operating position to the non-operating position when the cover 11 moves from the closed position to the open position.

As shown in FIG. 10(a), the release member 180 is connected to the cover 11 via a link 11A. When the cover 11 moves from the closed position shown in FIG. 10(a) to the open position shown in FIG. 10(b), the release member 180 moves linearly forward. In other words, the release member 180 can move in conjunction with the opening and closing of the cover 11.

As shown in FIG. 8, the release member 180 has a coupling interlocking member 181 that moves the coupling shaft 119, and a cam follower interlocking member 182 that moves the cam follower 170. The image forming device 1 also includes a stopper 183 that moves with the linear movement of the release member 180 in conjunction with the opening and closing of the cover 11 and is swingable relative to the release member 180, and a stopper biasing spring 184 that biases the stopper 183 (see FIGS. 11(a) and (b)). Although not shown, the coupling interlocking member 181 is supported by the housing 10 so that it can move linearly in the front-to-rear direction, which is the direction in which the photosensitive drums 50 are lined up.

The coupling interlocking member 181 has a through hole 181A and a coupling retraction cam 181B corresponding to each coupling shaft 119. The through hole 181A allows the tip of the coupling shaft 119 to pass through and engage with the coupling 65. The coupling retraction cam 181B has a surface that is inclined in the front-to-rear direction, and functions to move the coupling shaft 119 in the direction of the rotation axis to remove it from the coupling 65 when the release member 180 moves forward.

A total of four cam follower interlocking members 182 are provided, one for each cam follower 170. Each cam follower interlocking member 182 is fixed to the coupling interlocking member 181 and can move linearly back and forth together with the coupling interlocking member 181.

As shown in FIGS. 11(a) and 11(b), the cam follower interlocking member 182 has a release engagement portion 182A and a cam follower holding portion 182B.
The release engagement portion 182A protrudes upward at the rear side of the arm 173 of the cam follower 170 in the operating position, and is located at the rear side of the arm 173. Therefore, when the cover 11 moves from the closed position to the open position, and the release member 180 moves linearly forward, the release engagement portion 182A comes into contact with the arm 173, and is capable of rotating the cam follower 170 from the operating position to the non-operating position. In addition, when the cover 11 is located at the closed position and the cam follower 170 is located at the operating position, when the motor 3 rotates forward, the cam 150 rotates forward, and the first cam portion 152 guides the contact portion 172, the release engagement portion 182A comes into contact with the arm 173 to restrict the rotation of the cam follower 170 around the axis of the support shaft 179.

The cam follower holding portion 182B extends rearward from the upper end of the release engagement portion 182A. The cam follower holding portion 182B has an upward facing surface, and is the portion that comes into contact with the arm 173 of the cam follower 170 that is in the inoperative position when the cover 11 is moved from the closed position to the open position, thereby maintaining the position of the cam follower 170 (see FIG. 19).

The stopper 183 is rotatably supported at its front end by the cam follower interlocking member 182. Specifically, the stopper 183 is rotatable around an axis extending in the direction of the rotation axis, and is rotatable up and down between the rotation restricted position shown in FIG. 11(a) and the rotation permitted position shown in FIG. 11(b).

The stopper biasing spring 184 is arranged so as to constantly bias the stopper 183 from the rotation-permitted position toward the rotation-restricted position. In Figs. 11(a) and (b), the stopper biasing spring 184 is illustrated as a compression coil spring arranged below the stopper 183, but the stopper biasing spring may be a torsion spring or the like. When the stopper 183 is in the uppermost position, the upper surface of the stopper 183 is located below the upper surface of the cam follower holding portion 182B.

The stopper 183 is provided so that when the cover 11 moves from the open position to the closed position and the cam follower 170 is in the operating position, as shown in FIG. 11(a), the arm 173 is positioned between the release engagement portion 182A and the stopper 183. As a result, when the motor 3 rotates in the reverse direction and the cam 150 rotates in the reverse direction, and the first cam portion 152 guides the contact portion 172, the arm 173 comes into contact with the stopper 183 to restrict the rotation of the cam follower 170 from the operating position to the non-operating position (see FIG. 21(b)).

In this embodiment, the rotation direction of the motor 3 when the image forming device 1 forms an image is defined as forward rotation, and rotation in the opposite direction to the forward rotation is defined as reverse rotation. Also, in this embodiment, the rotation direction of the cam 150 when the motor 3 rotates forward and the cam 150 rotates forward corresponds to the "first rotation direction", and the rotation direction of the cam 150 when the motor 3 rotates reverse and the cam 150 rotates reverse corresponds to the "second rotation direction" opposite to the first rotation direction.

On the other hand, as shown in FIG. 11(b), when the cover 11 moves from the open position to the closed position and the cam follower 170 is in the inoperative position, the stopper 183 is pushed by the arm 173 to swing when the cam follower 170 rotates from the inoperative position to the operative position due to the biasing force of the first spring 176, thereby allowing the cam follower 170 to rotate from the inoperative position to the operative position.

Next, the configuration and function of the clutch 120 will be described.
12A and 12B, 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 disconnection state in which the driving force from the motor 3 is not transmitted to the developing roller 61. Specifically, the clutch 120 is configured to include a sun gear 121, a ring gear 122, and a carrier 123, which are elements that can rotate around one axis, and a planetary gear 124 supported by the carrier 123.

The sun gear 121 has a disk portion 121B that rotates integrally with the gear portion 121A, and a plurality of claw portions 121C provided on the outer periphery of the disk portion 121B. The claw portions 121C have a pointed tip that is inclined circumferentially toward one rotational direction.
The ring gear 122 has an inner gear 122A provided on its inner circumferential surface and an input gear 122B provided on its outer circumferential surface.

The carrier 123 has four shafts 123A that rotatably support the planetary gear 124. The carrier 123 also has an output gear 123B on its outer circumferential surface.

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

The clutch 120 has the input gear 122B meshing with the third idle gear 115, and the output gear 123B meshing with the coupling gear 117 (see FIG. 7). When the sun gear 121 is stopped from rotating, the clutch 120 is in a transmission state 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, the clutch 120 is in a disconnected state in which the driving force input to the input gear 122B cannot be transmitted to the output gear 123B. If a driving force is input to the input gear 122B while the clutch 120 is in a disconnected state and the output gear 123B is under load, the output gear 123B does not rotate, and the sun gear 121 spins freely.

9, the drive transmission mechanism 100 further includes a lever 160 that swings while being guided by the second cam portion 153. The lever 160 is swingably supported by a support shaft 102A fixed to the support plate 102. The levers 160 are provided for each of the colors yellow, magenta, cyan, and black. By working together with the cam 150, the lever 160 engages with the sun gear 121, which is one of the elements of the planetary gear mechanism, the sun gear 121, the ring gear 122, and the carrier 123, to restrict the sun gear 121 from rotating, thereby placing the clutch 120 in a transmission state, and disengages from the sun gear 121 to place the clutch 120 in a disconnected state. In other words, the lever 160 can switch the clutch 120 between a transmission state and a disconnected state.

Specifically, as shown in FIG. 13A , the lever 160 has a first lever 161 , a second lever 162 , and a second spring 163 .
The first lever 161 is capable of swinging around a swing axis X2 which is the central axis of the support shaft 102A, and is capable of coming into contact with the second cam portion 153. The first lever 161 has a rotation support portion 161A having a hole 161B which fits onto the support shaft 102A, a first arm 161C extending from the rotation support portion 161A, and a protrusion 161D protruding from the rotation support portion 161A on the opposite side to the first arm 161C.

The second lever 162 can be swung around the swing axis X2. The second lever 162 can be engaged with the sun gear 121, which is one element of the clutch 120. The second lever 162 is combined with the first lever 161, and as shown in Figures 13(b) and (c), can be swung relatively to the first lever 161 around the swing axis X2. In other words, the first lever 161 is combined with the second lever 162 so as to be swung around the swing axis X2 relative to the second lever 162. As shown in Figure 13(c), the position where the first lever 161 is swung relative to the second lever 162 against the biasing force of the second spring 163 is referred to as the "swing position".

The second lever 162 has a rotation support part 162A having a hole 162B that fits onto the support shaft 102A, a second arm 162C extending from the rotation support part 162A, a rotation restriction part 162D, and a spring hook part 162E. The rotation restriction part 162D protrudes from the second arm 162C in the direction in which the swing axis X2 extends. As shown in FIG. 13(b), the rotation restriction part 162D restricts the rotation of the second lever 162 in one direction relative to the first lever 161 by contacting the protrusion 161D.

The second spring 163 is a torsion spring, and biases the first lever 161 relative to the second lever 162 in a direction in which the protrusion 161D abuts against the rotation restricting portion 162D. In other words, the second spring 163 biases the first lever 161 so that it does not rotate relative to the second lever 162 when the rotation restricting portion 162D provided on the second lever 162 comes into contact with the protrusion 161D of the first lever 161.

When the first lever 161 and the second lever 162 are combined, the tip of the second arm 162C of the lever 160 extends toward the outer circumferential surface of the disk portion 121B of the sun gear 121. As shown in FIG. 17B, one end of the third spring 169 is hooked to the spring hook portion 162E. The third spring 169 is a tension spring, and the other end of the third spring 169 is hooked to a spring hook portion (not shown) of the support plate 102. As a result, the third spring 169 biases the second lever 162 clockwise in FIG. 17B. In other words, the third spring 169 biases the second arm 162C of the second lever 162 in a direction that swings it toward the outer circumferential surface of the sun gear 121 (disk portion 121B), which is one element of the planetary gear mechanism. The second arm 162C can restrict the rotation of the sun gear 121 by engaging with the claw portion 121C on the outer circumferential surface of the sun gear 121.

The tip of the first arm 161C of the lever 160 can come into contact with the outer circumferential surface of the second cam portion 153. The lever 160 can move between a transmission position, as shown in Figs. 17(a) and (b), in which the tip of the first lever 161 is separated from the second cam portion 153 and the second lever 162 engages with the claw portion 121C of the clutch 120 to put the clutch 120 in a transmission state, and a non-transmission position, as shown in Figs. 18(a) and (b), in which the tip of the first lever 161 comes into contact with the second cam portion 153 and is pushed and moved, so that the tip of the second lever 162 is disengaged from the claw portion 121C of the sun gear 121, which is one element of the planetary gear mechanism, to put the clutch 120 in a disconnected state.

When the motor 3 rotates in the reverse direction and the first lever 161 is pressed by the second cam portion 153 while the lever 160 is in the transmission position where the second lever 162 is engaged with the claw portion 121C of the sun gear 121, which is one element of the planetary gear mechanism, the first lever 161 swings relative to the second lever 162 against the biasing force of the second spring 163 and is positioned in the swing position, as shown in FIG. 22(a). In this way, the first lever 161 can swing relative to the second lever 162, so that excessive force is not applied to the lever 160 when the motor 3 is rotated in the reverse direction.

Next, the control by the control unit 2 will be described.
The control unit 2 is a device that controls the overall 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 program stored in advance.

In this embodiment, the control unit 2 controls the YMC clutch 140A and the K clutch 140K based on signals from the separation sensors 4C and 4K, and controls the contact and separation of the developing roller 61 with respect to the photosensitive drum 50.

When the cover 11 moves from the open position to the closed position, the control unit 2 starts rotating the cam 150, and after the cover 11 moves to the closed position, the control unit 2 stops the rotation of the cam 150 after the separation sensors 4C, 4K detect the detection portion 154 twice and before they detect it a third time.
For this reason, the control unit 2 performs the processes shown in, for example, FIGS.

As shown in FIG. 14, the control unit 2 determines whether the power is ON (S1), and if it determines that the power is ON (S1, Yes), it proceeds to step S2, and if it determines that the power is not ON (S1, No), it waits until the power is ON.

After the power is turned on, the control unit 2 judges whether the cover 11 is closed or not based on the signal of the open/close sensor (S2). If the control unit 2 judges that the cover 11 is not closed (S2, No), it waits until the cover 11 is closed, and if it judges that the cover 11 is closed (S2, Yes), it executes a cam reverse rotation separation process (S100) in which the cam 150 is rotated in the reverse direction to separate the developing roller 61 from the photosensitive drum 50. Thereafter, the control unit 2 judges whether the cover 11 is open or not based on the signal of the open/close sensor (S4). If the control unit 2 judges that the cover 11 is not open (S4, No), it waits until the cover 11 is opened, and if it judges that the cover 11 is open (S4, Yes), it proceeds to step S2 and repeats the process of waiting for the cover 11 to be closed.

As shown in FIG. 15, the control unit 2 executes a cam reverse rotation and separation process (S100) to return the cam 150 and the lever 160 and cam follower 170 acting on the cam 150 to their initial positions after the cover 11 is closed. In this process, the control unit 2 rotates the cam 150 in the reverse direction, and then rotates the cam 150 in the forward direction to bring the arm 173 of the cam follower 170 into contact with the release engagement portion 182A of the release member 180.

Specifically, the control unit 2 first rotates the motor 3 in the reverse direction (S101), and then turns on the YMC clutch 140A (S102). This causes the cams 150 (150Y, 150M, 150C) to rotate in the reverse direction.

Then, the control unit 2 determines whether the separation sensor 4C has turned ON (S111) and waits until it is determined that the separation sensor 4C has turned ON. If it is determined that the separation sensor 4C has turned ON (S111, Yes), the control unit 2 next determines whether the separation sensor 4C has turned OFF (S112) and waits until it is determined that the separation sensor 4C has turned OFF. Furthermore, if the control unit 2 determines that the separation sensor 4C has turned OFF (S112, Yes), the control unit 2 next determines whether the separation sensor 4C has turned ON (S113) and waits until it is determined that the separation sensor 4C has turned ON. If the control unit 2 determines that the separation sensor 4C has turned ON (S113, Yes), the control unit 2 next determines whether the separation sensor 4C has turned OFF (S114) and waits until it is determined that the separation sensor 4C has turned OFF. After determining that the separation sensor 4C has turned OFF (S114, Yes), the control unit 2 waits for a predetermined time to elapse (S115), and when it determines that the predetermined time has elapsed (S115, Yes), it turns OFF the YMC clutch 140A (S116) and stops the motor 3 (S117). When the YMC clutch 140A is turned OFF in step S116, the cams 150 (150Y, 150M, 150C) stop.
In other words, through the processing from steps S111 to S114, the control unit 2 stops the cam 150 (150Y, 150M, 150C) after a predetermined time has elapsed after the separation sensor 4C has turned ON twice (ON → OFF → ON → OFF) and then turned OFF.

Next, the control unit 2 rotates the motor 3 in the forward direction (S121) and turns on the YMC clutch 140A (S122). This causes the cams 150 (150Y, 150M, 150C) to rotate in the forward direction. The control unit 2 then determines whether the separation sensor 4C has been turned on (S123) and waits until it is determined that the sensor has been turned on. If the control unit 2 determines that the separation sensor 4C has been turned on (S123, Yes), it turns off the YMC clutch 140A (S124) and stops the motor 3 (S125). The cams 150 (150Y, 150M, 150C) stop when the YMC clutch 140A is turned off.
Note that, although the process for returning the cams 150 of the three colors, yellow, magenta, and cyan, to their initial positions has been described here, the same process can be performed in the case of black as well, except that the target sensor is the separation sensor 4K and the target clutch is the K clutch 140K, and so detailed explanation will be omitted.

The operation of each member in the image forming apparatus 1 which executes the above-mentioned control will be described with reference to the timing chart of FIG. 16 and FIGS. 17 to 24. FIG.
When the cover 11 is in the closed position and the image forming apparatus 1 is operating normally, the contact portion 172 of the cam follower 170 may be located on the first holding surface F1 of the first cam portion 152 (when the developing roller 61 is in the contact position) as shown in Figures 17(a) and 17(b) or may be located on the second holding surface F2 (when the developing roller 61 is in the separated position) as shown in Figures 18(a) and 18(b). In either case, when the motor 3 rotates forward and the cam 150 rotates forward (clockwise in Figures 17 and 18), the frictional force acting between the contact portion 172 and the first cam portion 152 pulls the contact portion 172 upward and urges the cam follower 170 counterclockwise in the figure, so that the posture of the cam follower 170 is determined by the contact of the arm 173 with the release engagement portion 182A.

18(a) and (b), that is, when the contact portion 172 is located on the second holding surface F2 and the developing roller 61 is in the separated position, when the cover 11 is moved from the closed position to the open position, the release member 180 is pulled by the cover 11 and moves forward in a straight line, as shown in FIG. 19(a) and (b). As a result, the coupling shaft 119 is pushed in the direction of the rotation axis by the coupling retraction cam 181B of the release member 180 and retracts, and is disengaged from the coupling 65. In addition, as the release member 180 moves forward in a straight line, the release engagement portion 182A urges the arm 173 of the cam follower 170 forward, rotating the cam follower 170 from the operating position to the non-operating position. Then, the cam follower holding portion 182B comes into contact with the arm 173, thereby holding the attitude of the cam follower 170. Therefore, as long as the cover 11 is open and the cam follower holding portion 182B holds the position of the cam follower 170, the cam follower 170 is held in the inoperative position regardless of the phase of the cam 150.

When the cam follower 170 rotates from the operating position to the non-operating position, the first spring 176 biases the cam follower 170 toward the standby position, so that the moment the contact portion 172 disengages from the first cam portion 152, the cam follower 170 moves from the protruding position to the standby position. This causes the developing roller 61 to move from the separated position to the contact position. With the cam follower 170 in the standby position, the shaft portion 171 comes out of the second opening 91A, so that even if the drawer 90 is pulled out of the housing 10 through the first opening 10A or the pulled-out drawer 90 is reattached, the shaft portion 171 does not interfere with the side frame 91L of the drawer 90.

After that, when the cover 11 is moved from the open position to the closed position, the cover sensor turns ON (see time t1 in FIG. 16), and the release member 180 moves linearly backward as shown in FIGS. 20(a) and 20(b). This causes the coupling shaft 119 to protrude and engage with the coupling 65. In addition, as the release member 180 moves linearly backward, the upper surface of the cam follower holding portion 182B no longer holds the arm 173 of the cam follower 170, but the contact portion 172 comes into contact with the outer peripheral surface of the first cam portion 152, so that the cam follower 170 is held in the inoperative position. At this time, the lower end of the arm 173 is located above the upper surface of the stopper 183, so it is not caught by the stopper 183, and the stopper 183 moves backward passing under the arm 173.

When the cover 11 is in the closed position, the contact portion 172 is located on the first holding surface F1 and the developing roller 61 is in the contact position, and when the cover 11 is moved from the closed position to the open position and then returned to the closed position, the cam follower 170 rotates due to the biasing force of the first spring 176, and can return to a position where the contact portion 172 can contact the first cam portion 152 (see Figures 17(a) and (b)). In other words, the cam follower 170 rotates from the inoperative position to the operative position when the cover 11 moves from the open position to the closed position.

After the cover 11 reaches the closed position, the control unit 2 rotates the motor 3 in the reverse direction (t2) and turns on the YMC clutch 140A (t3), causing the cam 150 to rotate in the reverse direction.
20(a) and 20(b), when the cam 150 rotates in the reverse direction as shown in Fig. 21(a), at the point when the wall of the first cam portion 152 separates from the contact portion 172, the cam follower 170 rotates counterclockwise in the drawing from the inoperative position to the operative position due to the biasing force of the first spring 176. At this time, the stopper 183 is pushed by the arm 173 of the cam follower 170 and swings downward once.

21(b), when the cam 150 further rotates in the reverse direction and the contact portion 172 comes into contact with the second guide surface F4 of the first cam portion 152, the frictional force between the second guide surface F4 and the contact portion 172 pushes the contact portion 172 downward, causing the cam follower 170 to rotate slightly clockwise in the figure. Then, the arm 173 hits the stopper 183, determining the position of the cam follower 170, after which the cam follower 170 is pushed by the second guide surface F4 and moves toward the protruding position without rotating.

When the cam 150 rotates further in the reverse direction from the state shown in FIG. 21(b), as shown in FIG. 22(a), the contact portion 172 is located on the second holding surface F2, and the shaft portion 171 is located in the protruding position, so that the developing roller 61 is located in the separated position (t4). Then, the detected portion 154 passes the separation sensor 4C, so that the signal of the separation sensor 4C turns ON (t5) and then turns OFF (t6). Then, the first lever 161 of the lever 160 hits the second cam portion 153. At this time, the second lever 162 remains in contact with the sun gear 121 and cannot move, so instead the first lever 161 swings against the biasing force of the second spring 163 to the swing position.

When the cam 150 further rotates in the reverse direction from the state shown in FIG. 22(a), the contact portion 172 is positioned on the first holding surface F1, as shown in FIG. 22(b), and the shaft portion 171 is positioned in the standby position, so that the developing roller 61 is positioned in the contact position (t7).

Then, as shown in FIG. 23(a), the cam 150 rotates in the reverse direction until the contact portion 172 is again positioned on the second holding surface F2, and after the developing roller 61 separates from the photosensitive drum 50 (t8), the detected portion 154 reaches the separation sensor 4C. The separation sensor 4C turns ON (t9). This is the second time that the separation sensor 4C detects the detected portion 154 since the cam 150 began to rotate in the reverse direction.

After that, when the cam 150 further rotates in the reverse direction, the control unit 2 turns off the YMC clutch 140A (t11) and stops the motor 3 (t12) when a predetermined time T1 has elapsed since the separation sensor 4C turned off (t10). This causes the cam 150 to stop as shown in FIG. 23(b). At this time, the first lever 161 of the lever 160 is no longer in contact with the second cam portion 153 and returns from the swing position to the normal position. In other words, the predetermined time T1 is set so that this timing occurs.

Then, the control unit 2 rotates the motor 3 in the forward direction (t13) and turns on the YMC clutch 140A (t14), thereby rotating the cam 150 in the forward direction. Then, after the cam 150 has rotated forward a predetermined angle, when the detected portion 154 reaches the separation sensor 4C and the separation sensor 4C turns on, the control unit 2 turns off the YMC clutch 140A (t15). Then, the control unit 2 stops the motor 3 (t16).

As a result, when the contact portion 172 is guided by the first guide surface F3 from the first holding surface F1 to the second holding surface F2, the frictional force between the contact portion 172 and the first guide surface F3 pushes the contact portion 172 upward, causing the cam follower 170 to rotate counterclockwise from the position shown in FIG. 23(b) to the position shown in FIG. 24. Then, the arm 173 comes into contact with the release engagement portion 182A, and the position of the cam follower 170 is set to the initial position.

As shown in FIG. 24, the contact portion 172 is located on the second holding surface F2, and the shaft portion 171 is located in the protruding position, so that the developing roller 61 is located in the separated position. In addition, the first lever 161 of the lever 160 is pushed by the second cam portion 153, so that the lever 160 is located in the non-transmitting position where the clutch 120 is in a disengaged state.

In this way, when the cover 11 is moved from the closed position to the open position and then moved back to the closed position, the developing roller 61 can be returned to its initial state in which it is separated from the photosensitive drum 50.

In this embodiment, the pressing surface 175 of the cam follower 170 tapers toward the pressed surface 192A, so the contact area between the pressing surface 175 and the pressed surface 192A of the developer cartridge 60 can be reduced. This reduces the load required to rotate the cam follower 170, and therefore the load required to open the cover 11.

In addition, because the pressing surface 175 has a spherical shape, the contact area between the pressing surface 175 and the pressed surface 192A can be made smaller than when the pressing surface has a truncated cone shape, for example. This makes it possible to reduce the load when rotating the cam follower 170.

In addition, since the pressing surface 175 is provided at one end of the shaft portion 171, the pressing surface 175 and the pressed surface 192A can be brought into contact with each other approximately on the axis of the shaft portion 171. This makes it difficult for the force applied to the pressing surface 175 from the pressed surface 192A to impede the rotation of the cam follower 170, making it possible to further reduce the load when rotating the cam follower 170.

In addition, because the pressed surface 192A of the developing cartridge 60 has a flat shape, even if the contact position between the pressing surface 175 and the pressed surface 192A shifts, the contact state between the pressing surface 175 and the pressed surface 192A can be made substantially uniform. This makes it possible to reduce the load when rotating the cam follower 170, regardless of the contact position between the pressing surface 175 and the pressed surface 192A.

In addition, by reducing the load required to rotate the cam follower 170, the cam follower 170 can be rotated from the inoperative position to the operative position without increasing the biasing force of the first spring 176.

In addition, by reducing the load when rotating the cam follower 170, the arm 173 can be reliably brought into contact with the release engagement portion 182A of the release member 180 when the rotation direction of the cam 150 is switched from reverse rotation to forward rotation. This improves the accuracy of the initial positions of the contact portion 172 and the first cam portion 152 after the cover 11 is closed to rotate the cam 150 and then the rotation of the cam 150 is stopped.

When the cover 11 is closed and the cam follower 170 rotates from the inoperative position to the operative position due to the biasing force of the first spring 176, the stopper 183 is pushed by the arm 173 and swings, allowing the cam follower 170 to rotate, so that the cam follower 170 can be returned from the inoperative position to the operative position by closing the cover 11. At this time, the load required to rotate the cam follower 170 can be reduced, allowing the cam follower 170 to operate smoothly.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment and can be modified as appropriate.

In the above embodiment, the pressing surface 175 has a spherical shape, but the pressing surface may have, for example, a truncated cone shape.

In the above embodiment, the second opening in the side wall is a recess or notch that opens upward, but the second opening may be a through hole in the side wall.

In the above embodiment, an image forming device 1 that prints color images using four color toners is exemplified, but the image forming device may be one that can only print in monochrome, or may be a device that prints color images using three or five color toners. The image forming device may also be a multifunction device or a copier.

Furthermore, the elements described in the above embodiments and variations can be implemented in appropriate combinations.

REFERENCE SIGNS LIST 1 Image forming apparatus 2 Control unit 5 Separation mechanism 10 Housing 10A First opening 11 Cover 50 Photosensitive drum 60 Development cartridge 61 Development roller 150 Cam 152 First cam portion 170 Cam follower 171 Shaft portion 172 Contact portion 173 Arm 175 Pressing surface 176 First spring 179 Support shaft 180 Release member 182A Release engagement portion 183 Stopper 192A Pressed surface

Claims (12)

A housing having an opening;
a cover movable between a closing position for closing the opening and an opening position for opening the opening;
A photosensitive drum;
a developing cartridge having a developing roller;
a separation mechanism that is 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 includes:
A cam having a first cam portion;
A support shaft provided in the housing;
a cam follower that is engaged with the support shaft, is slidable between a protruding position and a standby position along an axial direction of the support shaft, and is rotatable between an operating position and a non-operating position around an axis of the support shaft, the cam follower having a contact portion that is capable of contacting the first cam portion;
A release member that is movable in conjunction with the opening and closing of the cover,
the release member rotates the cam follower from the actuated position to the inactuated position when the cover moves from the closed position to the open position;
The cam follower is
When the cam is in the operating position, the contact portion is capable of contacting a cam surface on an end surface of the first cam portion in the axial direction, and as the cam rotates, the contact portion is guided by the first cam portion and is capable of sliding between the protruding position and the standby position,
When the developing cartridge is in the protruding position, the developing cartridge is pressed to position the developing roller in the separated position,
When the developing roller is in the standby position, the developing roller is positioned at the contact position;
When the contact portion is in the non-operating position, the contact portion cannot come into contact with the cam surface on the axial end surface of the first cam portion, the contact portion is not guided by the first cam portion, and is maintained at the standby position regardless of the rotation of the cam,
the cam follower has a pressing surface that presses the developing cartridge,
the developing cartridge has a pressed surface that is pressed by the pressing surface,
13. An image forming apparatus, comprising: a pressing surface having a shape tapered toward the pressed surface. The image forming device according to claim 1, characterized in that the pressing surface has a spherical shape. A housing having an opening;
a cover movable between a closing position for closing the opening and an opening position for opening the opening;
A photosensitive drum;
a developing cartridge having a developing roller;
a separation mechanism that is 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 includes:
A cam having a first cam portion;
A support shaft provided in the housing;
a cam follower that engages with the support shaft, is slidable between a protruding position and a standby position along an axial direction of the support shaft, and is rotatable around an axis of the support shaft between an operating position and a non-operating position, the cam follower having a contact portion that can come into contact with the first cam portion and an arm that extends in a direction away from the support shaft;
A release member that is movable in conjunction with the opening and closing of the cover,
the release member rotates the cam follower from the actuated position to the inactuated position when the cover moves from the closed position to the open position;
The cam follower is
When the cam is in the operating position, the contact portion is guided by the first cam portion as the cam rotates, and is slidable between the protruding position and the standby position;
When the developing cartridge is in the protruding position, the developing cartridge is pressed to position the developing roller in the separated position,
When the developing roller is in the standby position, the developing roller is positioned at the contact position;
When the contact portion is in the non-operating position, the contact portion is not guided by the first cam portion and is maintained at the standby position regardless of the rotation of the cam.
the cam follower has a pressing surface that presses the developing cartridge,
the developing cartridge has a pressed surface that is pressed by the pressing surface,
The pressing surface is tapered toward the pressed surface,
The pressing surface has a spherical shape,
the cam follower is engaged with the support shaft, is slidable relative to the support shaft, and has a shaft portion rotatable around an axis of the support shaft;
The image forming apparatus according to claim 1, wherein the pressing surface is provided at one end of the shaft portion in the axial direction. The image forming device according to any one of claims 1 to 3, characterized in that the pressed surface has a flat shape. The image forming apparatus according to any one of claims 1 to 4, characterized in that the spacing mechanism includes a spring that biases the cam follower from the non-operating position toward the operating position. A housing having an opening;
a cover movable between a closing position for closing the opening and an opening position for opening the opening;
A photosensitive drum;
a developing cartridge having a developing roller;
a separation mechanism that is 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 includes:
A cam having a first cam portion;
A support shaft provided in the housing;
a cam follower that engages with the support shaft, is slidable between a protruding position and a standby position along an axial direction of the support shaft, and is rotatable around an axis of the support shaft between an operating position and a non-operating position, the cam follower having a contact portion that can come into contact with the first cam portion and an arm that extends in a direction away from the support shaft;
A release member that is movable in conjunction with the opening and closing of the cover;
a spring that biases the cam follower from the inoperative position toward the operative position,
the release member rotates the cam follower from the actuated position to the inactuated position when the cover moves from the closed position to the open position;
The cam follower is
When the cam is in the operating position, the contact portion is guided by the first cam portion as the cam rotates, and is slidable between the protruding position and the standby position;
When the developing cartridge is in the protruding position, the developing cartridge is pressed to position the developing roller in the separated position,
When the developing roller is in the standby position, the developing roller is positioned at the contact position;
When the contact portion is in the non-operating position, the contact portion is not guided by the first cam portion and is maintained at the standby position regardless of the rotation of the cam.
the cam follower has a pressing surface that presses the developing cartridge,
the developing cartridge has a pressed surface that is pressed by the pressing surface,
The pressing surface is tapered toward the pressed surface,
the release member has a release engagement portion that contacts the arm to rotate the cam follower from the operating position to the non-operating position when the cover moves from the closed position to the open position,
an image forming apparatus characterized in that, when the cam follower is located in the operating position, the release engagement portion contacts the arm to regulate the rotation of the cam follower when the cam rotates in a first rotational direction and the first cam portion guides the contact portion. The image forming apparatus according to claim 6, further comprising a stopper that is provided so that the arm is positioned between the release engagement portion and the cam follower when the cam is positioned at the operating position, and that contacts the arm to restrict the rotation of the cam follower when the cam rotates in a second rotation direction opposite to the first rotation direction and the first cam portion guides the contact portion. A control unit is provided,
The image forming apparatus according to claim 7, characterized in that, when the cover moves from the open position to the closed position, the control unit rotates the cam in the second rotational direction, and then rotates the cam in the first rotational direction to bring the arm into contact with the release engagement portion. The stopper is
The cover is movable together with the release member in association with opening and closing of the cover, and is swingable relative to the release member.
An image forming apparatus as described in claim 7 or claim 8, characterized in that when the cover moves from the open position to the closed position, the cam follower rotates from the non-operating position toward the operating position due to the spring force, and is pushed by the arm to swing, allowing the cam follower to rotate from the non-operating position to the operating position. A housing having an opening;
a cover movable between a closing position for closing the opening and an opening position for opening the opening;
A photosensitive drum;
a developing cartridge having a developing roller movable between a contact position where the developing roller contacts the photosensitive drum and a spaced position where the developing roller is spaced from the photosensitive drum;
a separation mechanism capable of moving the developing roller between the contact position and the separation position,
A cam having a first cam portion;
a cam follower that is movable in a direction of a rotation axis of the developing roller between a protruding position and a standby position by being guided by the first cam portion as the cam rotates, the cam follower pressing the developing cartridge when located at the protruding position to position the developing roller at the separated position, and when located at the standby position to position the developing roller at the contact position;
and a spacing mechanism having
the cam follower is rotatable about an axis extending in the rotational axis direction between an operating position in which the cam follower can contact the first cam portion and a non-operating position in which the cam follower does not overlap with the first cam portion as viewed from the rotational axis direction, and rotates from the operating position to the non-operating position as the cover moves from the closed position to the open position,
an image forming apparatus, wherein the cam follower has a pressing surface that presses the developing cartridge, the pressing surface having a shape that tapers toward the developing cartridge in the direction of the rotation axis; The cam follower is
When the lever is located at the operating position, the lever is movable in the rotation axis direction between the protruding position and the standby position while being guided by the first cam portion as the cam rotates,
11. The image forming apparatus according to claim 10, wherein when the roller is located at the non-operating position, the roller is not guided by the first cam portion and is maintained at the standby position regardless of rotation of the cam. A release member movable in conjunction with the opening and closing of the cover is further provided,
12. The image forming apparatus according to claim 10, wherein the release member contacts the cam follower to rotate the cam follower from the operating position to the non-operating position when the cover moves from the closed position to the open position.

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