Image forming device

Abstract

To provide an image forming apparatus that reduces the size of a mechanism for controlling contact and separation of a developing roller and drive and stop of the developing roller.SOLUTION: An image forming apparatus comprises: a cam follower 110 that can make slide movement; a switching lever 140; and a linear motion plate 200 that can linearly move fore and aft between a first position and a second position. When the linear motion plate 200 is located at the first position, the cam follower 110 is located at a pressing position where it presses a developing cartridge to locate the developing cartridge at a separation position where a developing roller is separated from a photoconductor drum, and the switching lever 140 is located at a cut-off position where a driving force from a motor is not transmitted to the developing roller. When the linear motion plate 200 is located at the second position, the cam follower 110 is located at a non-pressing position where it locates the developing cartridge at a contact position where the developing roller is in contact with the photoconductor drum, and the switching lever 140 is located at a transmission position where the driving force from the motor can be transmitted to the developing roller.SELECTED DRAWING: Figure 11

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus having a photosensitive drum and a developing roller. [Background technology]

[0002] Conventionally, an image forming apparatus has been known that includes a photosensitive drum, a developing cartridge having a developing roller, a rotating cam, and a cam follower that can slide in the direction of the rotation axis of the developing roller as the cam rotates (Patent Document 1). In this technology, the cam rotates to slide the cam follower, which causes the cam follower to press the developing cartridge, thereby moving the developing roller from a position in contact with the photosensitive drum to a position separated from the photosensitive drum.

[0003] This technology also includes a clutch having a planetary gear mechanism that can be switched between a transmission state in which the driving force is transmitted to the developing roller and a disconnection state in which the driving force is not transmitted to the developing roller, and a lever that can swing between a position in which it engages with one element of the planetary gear mechanism to put the clutch in a transmission state and a position in which it disengages from the one element to put the clutch in a disconnection state, and the transmission and disconnection of the driving force to the developing roller are switched by rotating a cam to swing the lever. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-015149 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, with the trend toward smaller image forming apparatuses, it is desired to make compact the mechanisms for controlling the contact and separation of the developing roller and the driving and stopping of the developing roller.

[0006] Therefore, an object of the present invention is to provide an image forming apparatus that can make compact the mechanism for controlling the contact and separation of the developing roller and the driving and stopping of the developing roller. [Means for solving the problem]

[0007] an image forming device having a first photosensitive drum, the image forming device comprising: a motor; a first developing cartridge having a first developing roller, the first developing cartridge being movable between a contact position where the first developing roller contacts the first photosensitive drum and a separated position where the first developing roller is separated from the first photosensitive drum; a first cam follower being slidable in the direction of the rotational axis of the first developing roller between a pressing position where the first developing cartridge is pressed to position the first developing cartridge in the separated position and a non-pressing position where the first developing cartridge is positioned at the contact position; a first switching lever being movable between a transmission position where the driving force from the motor can be transmitted to the first developing roller and a disconnection position where the driving force from the motor is not transmitted to the first developing roller; and a linear motion plate being linearly movable in a direction perpendicular to the rotational axis between the first position and a second position, the linear motion moving the first cam follower between the pressing position and the non-pressing position and moving the first switching lever between the transmission position and the disconnection position. When the linear plate is in the first position, the first cam follower is in the pressing position and the first switching lever is in the disconnecting position, and when the linear plate is in the second position, the first cam follower is in the non-pressing position and the first switching lever is in the transmitting position.

[0008] With this configuration, the mechanism for controlling the contact and separation of the developing roller and the driving and stopping of the developing roller can be made compact.

[0009] The image forming device may also be configured to include a rotating cam that rotates in conjunction with the linear movement of the linear plate, the rotating cam being capable of contacting the first cam follower and having a first cam surface that is inclined with respect to the movement direction of the first cam follower, and the first cam surface slidingly moves the first cam follower between a pressed position and a non-pressed position as the rotating cam rotates.

[0010] In addition, the linear motion plate may have a second cam surface that is capable of contacting the first cam follower and is inclined with respect to the direction of movement of the linear motion plate, and that causes the first cam follower to slide between a pressing position and a non-pressing position due to the linear motion of the linear motion plate.

[0011] The image forming apparatus may also be configured to include a first spring that biases the first cam follower toward the non-pressing position.

[0012] According to this, when the linear motion plate is located at the second position, the first cam follower can be reliably located at the non-pressing position.

[0013] In addition, the linear motion plate may be configured to move the first switching lever to the transmission position before the first cam follower moves to the non-pressing position, and to move the first switching lever to the disconnecting position after the first cam follower moves to the pressing position.

[0014] According to this, the first developing roller can be rotated before coming into contact with the first photosensitive drum, and can be stopped after being separated from the first photosensitive drum.

[0015] The image forming device may also have a planetary gear mechanism having a sun gear, a ring gear, a carrier and a planetary gear, and a clutch that can be switched between a transmission state in which the driving force from the motor can be transmitted to the first developing roller and a disconnection state in which the driving force from the motor is not transmitted to the first developing roller, and the first switching lever may be configured such that when it is located in the transmission position, it engages with one element having any of the sun gear, ring gear and carrier of the planetary gear mechanism to place the clutch in the transmission state, and when it is located in the disconnection position, it disengages from the one element to place the clutch in the disconnection state.

[0016] The first switching lever may be configured to be swingable around a swing axis between a transmission position and a disconnection position, and may include a first lever swingable around the swing axis and swinging in conjunction with the linear motion of the linear plate, a second lever swingable around the swing axis and having a tip that can engage with one element when the first switching lever is in the transmission position and disengages from the one element when the first switching lever is in the disconnection position, a first protrusion provided on the first lever that restricts the swing of the second lever in a direction in which the tip of the second lever approaches the one element, and a second spring that urges the second lever against the first lever in a direction that brings the second lever into contact with the first protrusion, and the second lever may be configured to be swingable relative to the first lever against the urging force of the second spring.

[0017] This prevents excessive force from being applied to the first switching lever even if the tip of the second lever is repelled when engaging with one of the elements of the planetary gear mechanism.

[0018] The first lever may also be provided with a second protrusion that restricts the swinging of the second lever by contacting the second lever when the second lever swings a predetermined amount relative to the first lever against the biasing force of the second spring.

[0019] According to this, the swing range of the second lever can be defined by the first protrusion and the second protrusion.

[0020] The image forming apparatus may also be configured to include a third spring that biases the first switching lever toward the transmission position.

[0021] According to this, when the linear motion plate is located at the second position, the first switching lever can be reliably located at the transmission position.

[0022] The image forming apparatus also includes a second photosensitive drum and a second developing cartridge having a second developing roller, the second developing cartridge being movable between a contact position where the second developing roller is in contact with the second photosensitive drum and a separation position where the second developing roller is separated from the second photosensitive drum, a second cam follower being slidable in the direction of the rotation axis between a pressing position where the second developing cartridge is pressed to position the second developing cartridge at the separation position and a non-pressing position where the second developing cartridge is positioned at the contact position, and a second switching lever being movable between a transmission position where a driving force from a motor can be transmitted to the second developing roller and a disconnection position where the driving force from the motor is not transmitted to the second developing roller, and the linear motion plate is movable between a first position and a second position. The linear moving plate may be configured to be linearly movable between the first and second positions via a third position which is between the first and second positions, and to move the second cam follower between the pressing position and the non-pressing position and the second switching lever between the transmission position and the disconnection position by linear movement, such that when the linear moving plate is located at the first position, the second cam follower is located at the pressing position and the second switching lever is located at the disconnection position, when the linear moving plate is located at the second position, the second cam follower is located at the non-pressing position and the second switching lever is located at the transmission position, and when the linear moving plate is located at the third position, the first cam follower is located at the non-pressing position, the first switching lever is located at the transmission position, the second cam follower is located at the pressing position, and the second switching lever is located at the disconnection position.

[0023] According to this, when the linear motion plate is located at the first position, all of the developing rollers are separated from the corresponding photosensitive drums, when the linear motion plate is located at the third position, only the first developing roller is in contact with the first photosensitive drum, and when the linear motion plate is located at the second position, all of the developing rollers are in contact with the corresponding photosensitive drums.

[0024] In addition, the linear motion plate may be configured to move the second switching lever to the transmission position before the second cam follower moves to the non-pressing position, and to move the second switching lever to the disconnecting position after the second cam follower moves to the pressing position.

[0025] According to this, the second developing roller can be rotated before coming into contact with the second photosensitive drum, and can be stopped after being separated from the second photosensitive drum.

[0026] The first cam follower may have a pin that extends in the direction of the rotation axis and presses against the first developing cartridge. [Effects of the Invention]

[0027] According to the image forming apparatus described above, the mechanism for controlling the contact and separation of the developing roller and the driving and stopping of the developing roller can be made compact. [Brief explanation of the drawings]

[0028] [Figure 1] FIG. 1 is a diagram illustrating a schematic configuration of an image forming apparatus. [Figure 2] FIG. 2 is a side view showing the cam follower, the rotary cam, the developing drive gear train, the switching lever, the linear motion plate, and the frame of the first embodiment. [Figure 3] FIG. 2 is a perspective view showing a cam follower, a rotary cam, a compression coil spring, a first shaft, and a frame. [Figure 4] 1A and 1B are diagrams illustrating a configuration for moving a developer cartridge, in which FIG. 1A shows the developer cartridge at a separated position and FIG. 1B shows the developer cartridge at a contact position. [Figure 5] 1A is a perspective view of a cam follower, a rotary cam, and a first shaft as viewed from the first shaft side, and FIG. 1B is a perspective view as viewed from the cam follower side. [Figure 6] 1A is a cross-sectional view of a cam follower and a frame near the cam follower, and FIG. 1B is a cross-sectional view of the cam follower when it is in a pressing position and FIG. 1B is a cross-sectional view of the cam follower when it is in a non-pressing position. [Figure 7] 1A and 1B are perspective views showing a switching lever, an input gear, an output gear, and a clutch in an exploded state, in which FIG. 1A is a view from the transmission element side, and FIG. 1B is a view from the output element side. [Figure 8]1A is a side view of a switching lever, an input gear, a clutch, and an output gear, and FIG. 1B is a side view of the switching lever when it is in a disengagement position and when it is in a transmission position. [Figure 9] FIG. 1A is an exploded perspective view of the switching lever, FIG. 1B is a view showing a state in which the swing of the second lever is restricted by the first protrusion, and FIG. 1C is a view showing a state in which the swing of the second lever is restricted by the second protrusion. [Figure 10] FIG. 2 is a side view showing the cam follower, the rotary cam, the switching lever, the linear motion plate, and the frame. [Figure 11] 10A and 10B are diagrams illustrating the positions of the cam follower and the switching lever when the linear motion plate is located at a first position. [Figure 12] 10A and 10B are diagrams illustrating the positions of the cam follower and the switching lever when the linear motion plate is located between the first position and the third position. [Figure 13] 10A and 10B are diagrams illustrating the positions of the cam follower and the switching lever when the linear motion plate is located at a third position. [Figure 14] 10A and 10B are diagrams illustrating the positions of the cam follower and the switching lever when the linear motion plate is located between the third position and the second position. [Figure 15] 10A and 10B are diagrams illustrating the positions of the cam follower and the switching lever when the linear motion plate is located at a second position. [Figure 16] FIG. 10 is a perspective view showing a cam follower, a compression coil spring, a first shaft, a linear motion plate, and a frame according to a second embodiment. [Figure 17] FIG. 2 is a perspective view of the cam follower, the compression coil spring, the first shaft, and the linear motion plate as viewed from the frame side. [Figure 18] 1A is a cross-sectional view of a cam follower and a linear motion plate and a frame near the cam follower, and FIG. 1B is a view of the cam follower in a pressing position and a view of the cam follower in a non-pressing position. [Figure 19] 10A and 10B are diagrams illustrating the positions of the cam follower and the switching lever when the linear motion plate is located at a first position. [Figure 20]10A and 10B are diagrams illustrating the positions of the cam follower and the switching lever when the linear motion plate is located at a third position. [Figure 21] 10A and 10B are diagrams illustrating the positions of the cam follower and the switching lever when the linear motion plate is located at a second position. DETAILED DESCRIPTION OF THE INVENTION

[0029] Next, a first embodiment will be described. 1, image forming apparatus 1 is a color printer and includes a housing 10, a sheet supply unit 20, an image forming unit 30, and a control unit 2. In the embodiment, the right side of FIG. 1 is the front, the left side is the rear, the top and bottom are the top and bottom, and the front side of the paper in FIG. 1 is the left and the back side of the paper is the right.

[0030] The sheet supply unit 20 includes a sheet tray 21 on which the sheets S are set, and a supply mechanism 22. The supply mechanism 22 includes a pickup roller 23, a separation roller 24, a separation pad 25, a conveyance roller 26, and a registration roller 27. The sheets S in the sheet tray 21 are sent out by the pickup roller 23, then separated one by one between the separation roller 24 and the separation pad 25, and supplied to the image forming unit 30 by the conveyance roller 26 and the registration roller 27.

[0031] The image forming section 30 includes an exposure unit 40, a plurality of photosensitive drums 50, a plurality of developing cartridges 60, a transfer unit 70, and a fixing unit 80. The exposure unit 40 includes a light source, a deflector, a lens, a mirror, etc. (not shown). The exposure unit 40 emits a light beam (see the dashed line) to expose the surface of the photosensitive drum 50.

[0032] The photosensitive drums 50 include a first photosensitive drum 50K corresponding to black, a second photosensitive drum 50Y corresponding to yellow, a third photosensitive drum 50M corresponding to magenta, and a fourth photosensitive drum 50C corresponding to cyan. The third photosensitive drum 50M is disposed downstream of the second photosensitive drum 50Y in the conveying direction of the sheet S (hereinafter simply referred to as the "conveying direction"). The fourth photosensitive drum 50C is disposed downstream of the third photosensitive drum 50M in the conveying direction. The first photosensitive drum 50K is disposed downstream of the fourth photosensitive drum 50C in the conveying direction. That is, the second photosensitive drum 50Y, the third photosensitive drum 50M, the fourth photosensitive drum 50C, and the first photosensitive drum 50K are disposed in this order from the upstream side to the downstream side in the conveying direction.

[0033] In this specification and drawings, when describing components provided corresponding to each color by distinguishing between colors, the components are designated with the symbols Y, M, C, and K, and when describing components without distinguishing between colors, the components are not designated with the symbols Y, M, C, and K.

[0034] The developing cartridges 60 are provided corresponding to the respective photosensitive drums 50. In detail, the developing cartridges 60 include a first developing cartridge 60K having a first developing roller 61K that supplies toner to the first photosensitive drum 50K, a second developing cartridge 60Y having a second developing roller 61Y that supplies toner to the second photosensitive drum 50Y, a third developing cartridge 60M having a third developing roller 61M that supplies toner to the third photosensitive drum 50M, and a fourth developing cartridge 60C having a fourth developing roller 61C that supplies toner to the fourth photosensitive drum 50C.

[0035] The developing cartridge 60 is movable between a contact position shown by a solid line where the developing roller 61 contacts the corresponding photosensitive drum 50, and a separation position shown by a virtual line where the developing roller 61 is separated from the corresponding photosensitive drum 50.

[0036] Specifically, the first developing cartridge 60K is movable between a contact position where the first developing roller 61K is in contact with the first photosensitive drum 50K and a separated position where the first developing roller 61K is separated from the first photosensitive drum 50K. The second developing cartridge 60Y is movable between a contact position where the second developing roller 61Y is in contact with the second photosensitive drum 50Y and a separated position where the second developing roller 61Y is separated from the second photosensitive drum 50Y.

[0037] The third developing cartridge 60M is movable between a contact position where the third developing roller 61M contacts the third photosensitive drum 50M and a separated position where the third developing roller 61M is separated from the third photosensitive drum 50M. The fourth developing cartridge 60C is movable between a contact position where the fourth developing roller 61C contacts the fourth photosensitive drum 50C and a separated position where the fourth developing roller 61C is separated from the fourth photosensitive drum 50C.

[0038] The photosensitive drums 50 are rotatably supported in a drawer 55. A charger 52 for charging the photosensitive drum 50 is provided in the drawer 55 corresponding to each photosensitive drum 50. The drawer 55 detachably supports a plurality of developing cartridges 60. The drawer 55 is detachable from the housing 10 through an opening 10A in the housing 10 that is exposed when the front cover 11 is opened.

[0039] The transfer unit 70 includes a drive roller 71, a driven roller 72, an endless conveyor belt 73, and four transfer rollers 74. The conveyor belt 73 is stretched between the drive roller 71 and the driven roller 72, and its outer surface is in contact with each photosensitive drum 50. The transfer rollers 74 are disposed inside the conveyor belt 73, and sandwich the conveyor belt 73 between themselves and the corresponding photosensitive drum 50.

[0040] The fixing unit 80 includes a heating roller 81 and a pressure roller 82 disposed opposite the heating roller 81. A conveying roller 15 and a discharging roller 16 are provided downstream of the fixing unit 80 in the conveying direction.

[0041] In the image forming section 30, the surface of the photosensitive drum 50 is uniformly charged by the charger 52 and then exposed to a light beam emitted from the exposure unit 40. As a result, an electrostatic latent image based on image data is formed on the photosensitive drum 50. Furthermore, toner contained in the developer cartridge 60 is carried on the surface of the developer roller 61 and supplied from the developer roller 61, which is positioned at a contact position, to the electrostatic latent image formed on the photosensitive drum 50. As a result, a toner image is formed on the photosensitive drum 50.

[0042] The toner image formed on the photosensitive drum 50 is transferred onto the sheet S when the sheet S is fed onto the conveyor belt 73 and conveyed on the conveyor belt 73 and passes between the photosensitive drum 50 and the transfer roller 74. The toner image is then fixed onto the sheet S when the sheet S passes between the heating roller 81 and the pressure roller 82. Thereafter, the sheet S is discharged onto the discharge tray 13 by the conveyor roller 15 and the discharge roller 16.

[0043] 2, the image forming apparatus 1 further includes a first motor M1, a second motor M2, a cam follower 110, a rotating cam 120, a development drive gear train 130, a switching lever 140, and a linear motion plate 200. The housing 10 also includes a frame 300. The first motor M1 is a drive source that drives the developing roller 61, and the second motor M2 is a drive source that drives the linear motion plate 200. The first motor M1 corresponds to the "motor".

[0044] As shown in Fig. 3, the cam follower 110 is slidable in the direction of the rotational axis of the first developing roller 61K (corresponding to the direction in which the dashed line shown in Fig. 3 extends; hereinafter, simply referred to as the "rotational axis direction"). In more detail, the cam follower 110 slides in the direction of the rotational axis between a pressing position shown in Fig. 4(a) where it presses the developing cartridge 60 to position the developing cartridge 60 at the separated position, and a non-pressing position shown in Fig. 4(b) where it positions the developing cartridge 60 at the contact position.

[0045] As shown in FIGS. 4(a) and 4(b), the developer cartridge 60 is supported in the drawer 55 so as to be movable back and forth. The drawer 55 has a contact portion 55A and a pressing member 55B. The contact portion 55A is the portion that a slide member 66 (described later) contacts, and is made of a roller that can rotate around a vertical axis. The pressing member 55B is biased rearward by a spring 55C, and when the developer cartridge 60 is installed in the drawer 55, it presses the developer cartridge 60 to move it to a contact position where the developing roller 61 contacts the photosensitive drum 50.

[0046] The developer cartridge 60 has a case 65 that contains toner, and a slide member 66. The slide member 66 is slidable in the direction of the rotation axis relative to the case 65, and is caused to slide in the direction of the rotation axis by being pressed by a cam follower 110. The slide member 66 has a shaft 66A slidably supported by the case 65, a first contact member 66B provided at one end of the shaft 66A, and a second contact member 66C provided at the other end of the shaft 66A.

[0047] The first contact member 66B has a pressing surface 66D and an inclined surface 66E inclined relative to the axial direction, and the second contact member 66C has an inclined surface 66F inclined similarly to the inclined surface 66E. The pressing surface 66D is pressed by the cam follower 110. When the slide member 66 is pressed by the cam follower 110, the inclined surfaces 66E and 66F come into contact with the contacted portion 55A and urge the developer cartridge 60 in a direction perpendicular to the rotational axis direction, moving the developer roller 61 to a spaced position where it is spaced from the photosensitive drum 50. A spring 67 is disposed between the first contact member 66B and the case 65 to urge the slide member 66 leftward.

[0048] Returning to FIG. 3, the cam followers 110 include a first cam follower 110K, a second cam follower 110Y, a third cam follower 110M, and a fourth cam follower 110C.

[0049] The first cam follower 110K slides in the direction of the rotation axis between a pressing position where it presses the first developer cartridge 60K to position the first developer cartridge 60K at the separated position and a non-pressing position where it positions the first developer cartridge 60K at the contact position. The second cam follower 110Y slides in the direction of the rotation axis between a pressing position where it presses the second developer cartridge 60Y to position the second developer cartridge 60Y at the separated position and a non-pressing position where it positions the second developer cartridge 60Y at the contact position.

[0050] The third cam follower 110M slides in the direction of the rotation axis between a pressing position where it presses the third developer cartridge 60M to position it at the separated position and a non-pressing position where it positions the third developer cartridge 60M at the contact position. The fourth cam follower 110C slides in the direction of the rotation axis between a pressing position where it presses the fourth developer cartridge 60C to position it at the separated position and a non-pressing position where it positions the fourth developer cartridge 60C at the contact position.

[0051] As shown in Figures 5(a) and (b), the cam follower 110 (first cam follower 110K, second cam follower 110Y, third cam follower 110M and fourth cam follower 110C) has a pin 111, a first flange portion 112, a connecting wall portion 113, a second flange portion 114, a cam contact portion 115 and a rotation regulating portion 116.

[0052] When the cam follower 110 moves from the non-pressing position to the pressing position, the pin 111 presses the corresponding developer cartridge 60. For example, the pin 111 of the first cam follower 110K presses the first developer cartridge 60K. The pin 111 extends in the direction of the rotation axis. The pin 111 has a cylindrical shape with a bottom and one side in the direction of the rotation axis closed.

[0053] The image forming apparatus 1 includes a first shaft 119 extending in the direction of the rotation axis. The first shaft 119 is provided in the housing 10. Four first shafts 119 are provided corresponding to the cam followers 110 (see FIG. 3). The pins 111 are engaged with the first shafts 119, and are supported so as to be slidable in the direction of the rotation axis relative to the housing 10. This allows the cam followers 110 to slide in the direction of the rotation axis between a pressed position and a non-pressed position.

[0054] The first flange portion 112 extends from the outer peripheral surface of the pin 111 toward the outside in the radial direction of the pin 111. The connecting wall portion 113 connects the first flange portion 112 and the second flange portion 114. The connecting wall portion 113 has a cylindrical shape and extends from the radially outer end of the first flange portion 112 toward one side in the rotational axis direction. The second flange portion 114 extends from one end of the connecting wall portion 113 in the rotation axis direction toward the outside in the radial direction of the connecting wall portion 113.

[0055] The cam contact portion 115 comes into contact with a first cam surface 126 of the rotating cam 120, which will be described later. The cam contact portion 115 extends from a part of the radially outer end portion of the second flange portion 114 toward the other side in the direction of the rotation axis. The cam contact portion 115 has an arc-shaped wall shape centered on the central axis of the pin 111. Two cam contact portions 115 are provided. The two cam contact portions 115 have shapes that are point-symmetric with respect to the central axis of the pin 111. The surface of the cam contact portion 115 that faces the first cam surface 126 in the rotation direction of the rotating cam 120 is an inclined surface 115A that is approximately parallel to the first cam surface 126.

[0056] The rotation restricting portions 116 have a rib shape that protrudes from the outer peripheral surface of the cam contact portion 115 toward the outside in the radial direction of the pin 111 and extends in the direction of the rotation axis. Two rotation restricting portions 116 are provided corresponding to each cam contact portion 115. The rotation restricting portions 116 are provided so as to protrude from the end of the arc-shaped cam contact portion 115 opposite the inclined surface 115A of the cam contact portion 115 in the circumferential direction.

[0057] The rotating cam 120 rotates in conjunction with the linear movement of the linear motion plate 200, thereby sliding the cam follower 110 between the pressing position and the non-pressing position. As shown in Fig. 3, the rotating cam 120 includes a first rotating cam 120K that slides the first cam follower 110K between the pressing position and the non-pressing position, a second rotating cam 120Y that slides the second cam follower 110Y between the pressing position and the non-pressing position, a third rotating cam 120M that slides the third cam follower 110M between the pressing position and the non-pressing position, and a fourth rotating cam 120C that slides the fourth cam follower 110C between the pressing position and the non-pressing position.

[0058] Returning to Figure 5, the rotating cam 120 (first rotating cam 120K, second rotating cam 120Y, third rotating cam 120M and fourth rotating cam 120C) has a ring-shaped disk portion 121, a first cam portion 122, a cam arm 123 and a cam boss 124.

[0059] The first cam portion 122 has an arc-shaped wall shape centered on the rotation center of the rotating cam 120, and protrudes from the disk portion 121 toward one side in the rotation axis direction. Two first cam portions 122 are provided. The two first cam portions 122 have shapes that are point-symmetric with respect to the rotation center of the rotating cam 120.

[0060] The pivoting cam 120 further includes a first holding surface 125, a first cam surface 126, and a second holding surface 127. The first holding surface 125 is an end surface on one side in the rotational axis direction of the first cam portion 122, and holds the corresponding cam follower 110 in the pressing position. The first holding surface 125 is approximately perpendicular to the rotational axis direction.

[0061] The second holding surface 127 is a part of the end surface on one side in the rotational axis direction of the disc portion 121, and holds the corresponding cam follower 110 in a non-pressing position. The second holding surface 127 is approximately perpendicular to the rotational axis direction. The second holding surface 127 is located at the same position as the first holding surface 125 in the radial direction of a circle centered on the rotation center of the rotating cam 120.

[0062] First cam surface 126 is a surface connecting first holding surface 125 and second holding surface 127, and causes corresponding cam follower 110 to slide between a pressing position and a non-pressing position as rotating cam 120 rotates. For example, first cam surface 126 of first rotating cam 120K causes first cam follower 110K to slide between a pressing position and a non-pressing position as first rotating cam 120K rotates.

[0063] The first cam surface 126 is capable of coming into contact with the cam contact portion 115 of the corresponding cam follower 110, and is inclined with respect to the movement direction of the corresponding cam follower 110. For example, the first cam surface 126 of the first pivoting cam 120K is capable of coming into contact with the cam contact portion 115 of the first cam follower 110K, and is inclined with respect to the movement direction of the first cam follower 110K. The first cam surface 126 is provided on the first cam portion 122. The first cam surface 126 is inclined so as to approach the corresponding developer cartridge 60 (the front side in FIG. 5(b)) as it moves from the second holding surface 127 toward the first holding surface 125.

[0064] The cam arm 123 extends from the end of the first cam portion 122 opposite the first cam surface 126 and from the disk portion 121 in the radial direction of a circle centered on the rotation center of the rotating cam 120. The cam boss 124 is provided so as to extend toward one side in the rotation axis direction from the tip of the cam arm 123. The cam boss 124 has a cylindrical shape.

[0065] As shown in FIGS. 6(a) and 6(b), the frame 300 has a plate-shaped main body 310, a through hole 320, and a cam support portion 330. The through-holes 320 are holes through which the pins 111 of the cam followers 110 pass. As shown in FIG. 6(a), when the cam followers 110 are in the pressing position, the pins 111 protrude from the frame 300 and press the developer cartridge 60, and as shown in FIG. 6(b), when the cam followers 110 are in the non-pressing position, the pins 111 retract and no longer press the developer cartridge 60. Four through-holes 320 are provided, one for each cam follower 110.

[0066] The cam support portion 330 is a portion that rotatably supports the rotating cam 120. As shown in FIG. 3, the cam support portion 330 has a substantially cylindrical shape, and four cam support portions 330 are provided corresponding to the respective rotating cams 120. The cam support portions 330 are provided so as to protrude in the direction of the rotation axis from the portion of the main body portion 310 around the through-hole 320 (see FIG. 6). The rotating cam 120 is rotatable relative to the frame 300 with the first cam portion 122 engaged with the cam support portion 330.

[0067] Cam support portion 330 has a pair of rotation restriction grooves 331 extending in the direction of the rotation axis. Rotation of cam follower 110 around first shaft 119 is restricted by rotation restriction portions 116 engaging with the corresponding rotation restriction grooves 331 of cam support portion 330.

[0068] The image forming apparatus 1 includes compression coil springs 150 as an example of first springs. Four compression coil springs 150 are provided corresponding to the cam followers 110. The compression coil springs 150 bias the corresponding cam followers 110 toward the non-pressing position. For example, the compression coil spring 150 provided corresponding to the first cam follower 110K biases the first cam follower 110K toward the non-pressing position.

[0069] As shown in Fig. 6(b), compression coil spring 150 is disposed between the area around through-hole 320 of main body portion 310 of frame 300 and first flange portion 112 of cam follower 110. When cam follower 110 slides from the non-pressing position shown in Fig. 6(b) to the pressing position shown in Fig. 6(a), compression coil spring 150 is compressed, and the restoring force generated at this time urges first flange portion 112 in a direction away from main body portion 310. In this way, compression coil spring 150 urges cam follower 110 from the pressing position toward the non-pressing position.

[0070] 2, the development drive gear train 130 is capable of transmitting the driving force of the first motor M1 to the development cartridges 60. The development drive gear train 130 includes four input gears 131 (131K, 131Y, 131M, 131C), four clutches 160 (160K, 160Y, 160M, 160C), and four output gears 133 (133K, 133Y, 133M, 133C), each provided corresponding to one of the development cartridges 60.

[0071] The input gear 131 is a gear to which the driving force from the first motor M1 is input. The output gear 133 is a gear that outputs the driving force from the first motor M1 to the corresponding developing cartridge 60 (developing roller 61).

[0072] The clutch 160 is switchable between a transmission state in which the driving force from the first motor M1 can be transmitted to the corresponding developing roller 61 and a disconnection state in which the driving force from the first motor M1 is not transmitted to the corresponding developing roller 61. For example, the clutch 160K is switchable between a transmission state in which the driving force from the first motor M1 can be transmitted to the first developing roller 61K and a disconnection state in which the driving force from the first motor M1 is not transmitted to the first developing roller 61K.

[0073] 7(a) and (b), the clutch 160 (160K, 160Y, 160M, 160C) has a planetary gear mechanism including a sun gear 161, a ring gear 162, a carrier 163, and two planetary gears 164. The clutch 160 has an input element 160A, an output element 160B, and a transfer element 160D. The input element 160A, the output element 160B, and the transfer element 160D are rotatable coaxially.

[0074] Clutch 160 has an input element 160A, an output element 160B, and a transmission element 160D, one of which has a sun gear 161, one other than the element having sun gear 161 has a ring gear 162, and the remaining one has a carrier 163. In this embodiment, transmission element 160D has the sun gear 161, input element 160A has the ring gear 162, and output element 160B has the carrier 163.

[0075] The input element 160A is an element to which a driving force is input, and has a ring gear 162 and a first outer peripheral gear 165 formed on the outer periphery of the ring gear 162. The first outer peripheral gear 165 meshes with the input gear 131. The output element 160B is an element that outputs driving force, and has a carrier 163 and a second outer peripheral gear 166 formed on the outer periphery of the carrier 163. The second outer peripheral gear 166 meshes with the output gear 133. The carrier 163 also has two shaft portions 163A that rotatably support the planetary gear 164.

[0076] Transfer element 160D is an element configured to be able to transmit driving force from input element 160A to output element 160B when rotation is restricted, and not to transmit driving force from input element 160A to output element 160B when rotation is not restricted. Transfer element 160D has a sun gear 161, a rotating plate 167 that rotates integrally with sun gear 161, and a plurality of claws 168 provided on the outer periphery of rotating plate 167. The planetary gear 164 is rotatably supported by a shaft portion 163A of the carrier 163. The planetary gear 164 meshes with the sun gear 161 and the ring gear 162.

[0077] When the rotation of the transfer element 160D is stopped, the clutch 160 is in a transfer state where the driving force input to the first outer peripheral gear 165 can be transferred to the second outer peripheral gear 166. On the other hand, when the transfer element 160D is rotatable, the clutch 160 is in a disengaged state where the driving force input to the first outer peripheral gear 165 cannot be transferred to the second outer peripheral gear 166. When the clutch 160 is in a disengaged state and a load is applied to the second outer peripheral gear 166, and a driving force is input to the first outer peripheral gear 165, the output element 160B does not rotate and the transfer element 160D spins freely.

[0078] The switching lever 140 is movable between a transmission position shown in Fig. 8(b) where the driving force from the first motor M1 can be transmitted to the developing roller 61, and a disconnection position shown in Fig. 8(a) where the driving force from the first motor M1 is not transmitted to the developing roller 61. As shown in Fig. 2, the switching lever 140 includes a first switching lever 140K, a second switching lever 140Y, a third switching lever 140M, and a fourth switching lever 140C.

[0079] The first switching lever 140K is movable between a transmission position where the driving force can be transmitted to the first developing roller 61K and a disconnection position where the driving force is not transmitted to the first developing roller 61K. The second switching lever 140Y is movable between a transmission position where the driving force can be transmitted to the second developing roller 61Y and a disconnection position where the driving force is not transmitted to the second developing roller 61Y.

[0080] The third switching lever 140M is movable between a transmission position where the driving force can be transmitted to the third developing roller 61M and a disconnection position where the driving force is not transmitted to the third developing roller 61M. The fourth switching lever 140C is movable between a transmission position where the driving force can be transmitted to the fourth developing roller 61C and a disconnection position where the driving force is not transmitted to the fourth developing roller 61C.

[0081] As shown in FIG. 8(b), when the switching lever 140 is located at the transmission position, it engages with the claw portion 168 of the transfer element 160D to put the clutch 160 in the transmission state. In the embodiment, the transfer element is an example of "one element having any of the sun gear, ring gear, and carrier of the planetary gear mechanism." Also, as shown in FIG. 8(a), when the switching lever 140 is located at the disengagement position, it disengages from the claw portion 168 of the transfer element 160D to put the clutch 160 in the disengagement state. The switching lever 140 is swingable between the transmission position and the disengagement position around the swing axis 140A, which is the central axis of the second shaft 340.

[0082] The second shaft 340 is a shaft that supports the switching lever 140 so that the switching lever 140 can swing, and is provided on the frame 300 as shown in Fig. 3. The second shaft 340 extends in the direction of the rotation axis. Four second shafts 340 are provided, one for each switching lever 140.

[0083] As shown in FIG. 9(a), the switching lever 140 (first switching lever 140K, second switching lever 140Y, third switching lever 140M and fourth switching lever 140C) has a first lever 141, a second lever 142 and a torsion spring 143 as an example of a second spring.

[0084] The first lever 141 is swingable around a swing shaft 140A and swings in conjunction with the linear motion of the linear motion plate 200. The first lever 141 has a first support portion 141A, a first arm 141B, a lever boss 141C, a first protrusion 141E, a second protrusion 141F, a first spring contact portion 141G, and a spring hook portion 141H.

[0085] The first support portion 141A has a cylindrical shape, and is supported by engaging with the second shaft 340 so as to be swingable around the swing axis 140A. The first arm 141B extends from the outer circumferential surface of the first support portion 141A toward the outside in the radial direction of the first support portion 141A. The lever boss 141C protrudes from the tip of the first arm 141B toward one side in the direction of the rotation axis. The lever boss 141C has a cylindrical shape.

[0086] The first protrusion 141E and the second protrusion 141F protrude from the outer circumferential surface of the first support portion 141A toward the outside in the radial direction of the first support portion 141A. The first protrusion 141E and the second protrusion 141F protrude in a direction different from that of the first arm 141B. The first protrusion 141E and the second protrusion 141F are provided spaced apart in the circumferential direction of the first support portion 141A. The first spring contact portion 141G and the spring hook portion 141H protrude from the first arm 141B toward the other side in the direction of the rotation axis.

[0087] The second lever 142 is pivotable around the pivot shaft 140A and is engageable with the transmission element 160D of the clutch 160. The second lever 142 has a second support portion 142A, a second arm 142B, a tip 142C, a lever protrusion 142D, and a second spring contact portion 142G.

[0088] The second support portion 142A has a cylindrical shape, and is supported so as to be swingable around the swing shaft 140A by engaging with the first support portion 141A of the first lever 141. The second lever 142 can also swing relatively to the first lever 141 around the swing shaft 140A. The second arm 142B extends from the outer circumferential surface of the second support portion 142A toward the outside in the radial direction of the second support portion 142A.

[0089] The tip 142C protrudes from the tip of the second arm 142B toward the transfer element 160D (see FIG. 9(b)). The tip 142C can engage with the claw portion 168 of the transfer element 160D when the switching lever 140 is in the transmission position, and disengages from the claw portion 168 of the transfer element 160D when the switching lever 140 is in the disengagement position. For example, the tip 142C of the first switching lever 140K can engage with the claw portion 168 of the transfer element 160D when the first switching lever 140K is in the transmission position, and disengages from the claw portion 168 of the transfer element 160D when the first switching lever 140K is in the disengagement position.

[0090] The lever protrusion 142D protrudes from the second support portion 142A toward the other side in the rotation axis direction. As shown in Fig. 9(b), the lever protrusion 142D is disposed between the first protrusion 141E and the second protrusion 141F of the first lever 141 in a state in which the second lever 142 is assembled to the first lever 141. The second spring contact portion 142G protrudes from the second arm 142B toward the other side in the direction of the rotation axis.

[0091] Torsion spring 143 biases second lever 142 toward first lever 141 in a direction that brings lever protrusion 142D of second lever 142 into contact with first protrusion 141E provided on first lever 141. Torsion spring 143 has a coil 143A, a first spring arm 143B extending from one end of coil 143A toward the outside in the radial direction of coil 143A, and a second spring arm 143C extending from the other end of coil 143A toward the outside in the radial direction of coil 143A.

[0092] The torsion spring 143 is disposed with the coil 143A engaged with the second shaft 340, the first spring arm 143B in contact with the first spring contact portion 141G, and the second spring arm 143C in contact with the second spring contact portion 142G. The torsion spring 143 biases the second lever 142 clockwise in FIG. 9(b), causing the lever protrusion 142D to contact the first protrusion 141E. The first protrusion 141E restricts the swing of the second lever 142 in a direction in which the tip 142C of the second lever 142 approaches the transfer element 160D.

[0093] 9(c), the second lever 142 can swing counterclockwise in the figure relative to the first lever 141 against the biasing force of the torsion spring 143. A second protrusion 141F is provided on the first lever 141. When the second lever 142 swings a predetermined amount counterclockwise in the figure relative to the first lever 141 against the biasing force of the torsion spring 143, a lever protrusion 142D of the second lever 142 comes into contact with the second protrusion 141F, thereby restricting further swing of the second lever 142.

[0094] Returning to FIG. 9(b), the image forming apparatus 1 includes tension coil springs 144 as an example of a third spring. Four tension coil springs 144 are provided corresponding to the switching levers 140 (see FIG. 2). The tension coil springs 144 bias the corresponding switching levers 140 toward the transmission position. For example, the tension coil spring 144 provided corresponding to the first switching lever 140K biases the first switching lever 140K toward the transmission position.

[0095] More specifically, one end of the tension coil spring 144 is hooked to a spring hook 141H provided on the first lever 141, and the other end, in a slightly stretched state, is hooked to a spring hook (not shown) provided on the housing 10 at a position forward of the spring hook 141H. As a result, the tension coil spring 144 biases the switching lever 140 in the clockwise direction in the drawing, which is the direction in which the tip 142C approaches the transfer element 160D. As a result, the tension coil spring 144 biases the switching lever 140 from the disconnection position toward the transfer position.

[0096] As shown in Fig. 10, the linear motion plate 200 is supported by the frame 300 (housing 10) so as to be linearly movable. Specifically, the linear motion plate 200 is linearly movable in a direction perpendicular to the direction of the rotation axis between a first position shown in Fig. 11 and a second position shown in Fig. 15. Specifically, the linear motion plate 200 is linearly movable in the front-rear direction, which is the direction in which the photosensitive drums 50 are arranged, between the first position and the second position. The second position is a position before the first position.

[0097] The linear motion plate 200 can move linearly between the first position and the second position via a third position shown in Fig. 13. The third position is a position between the first position and the second position. In this embodiment, the linear motion plate 200 can move linearly forward from the first position to the third position and from the third position to the second position, and can also move linearly backward from the second position to the third position and from the third position to the first position.

[0098] Returning to Fig. 10, the frame 300 has a plurality of guides 351 to 359. Each of the guides 351 to 359 is provided to protrude from the main body 310 in the direction of the rotation axis and extend forward and backward. The guides 351 to 355 are provided above the linear motion plate 200, and the guides 356 to 359 are provided below the linear motion plate 200. The guides 351 to 355 and the guides 356 to 359 hold the linear motion plate 200 so as to sandwich it from above and below, and support the linear motion plate 200 so that it can move linearly forward and backward.

[0099] The linear motion plate 200 is provided so as to move the first cam follower 110K between the pressing position and the non-pressing position and to move the first switching lever 140K between the disengagement position and the transmission position by linear motion in the front-rear direction. The linear motion plate 200 is also provided so as to move the second cam follower 110Y, the third cam follower 110M, and the fourth cam follower 110C between the pressing position and the non-pressing position and to move the second switching lever 140Y, the third switching lever 140M, and the fourth switching lever 140C between the disengagement position and the transmission position by linear motion in the front-rear direction.

[0100] 11, when the linear motion plate 200 is in the first position, the first cam follower 110K is in the pressing position, and the first switching lever 140K is in the disengagement position. The second cam follower 110Y, the third cam follower 110M, and the fourth cam follower 110C are in the pressing position, and the second switching lever 140Y, the third switching lever 140M, and the fourth switching lever 140C are in the disengagement position. At this time, the image forming apparatus 1 is in a state where all of the developer cartridges 60 are in the separated position, and the driving force from the first motor M1 is not transmitted to any of the developer rollers 61.

[0101] 13, when the linear motion plate 200 is in the third position, the first cam follower 110K is in the non-pressing position, and the first switching lever 140K is in the transmitting position. The second cam follower 110Y, the third cam follower 110M, and the fourth cam follower 110C are in the pressing position, and the second switching lever 140Y, the third switching lever 140M, and the fourth switching lever 140C are in the disconnecting position. At this time, the image forming apparatus 1 is in a state in which the first black developing cartridge 60K is in the contact position, and the driving force from the first motor M1 can be transmitted to the first developing roller 61K. The yellow, magenta, and cyan developing cartridges 60Y, 60M, and 60C are in the separated positions, and the driving force from the first motor M1 is not transmitted to the developing rollers 61Y, 61M, and 61C.

[0102] 15, when the linear motion plate 200 is in the second position, the first cam follower 110K is in the non-pressing position, and the first switching lever 140K is in the transmitting position. The second cam follower 110Y, the third cam follower 110M, and the fourth cam follower 110C are in the non-pressing position, and the second switching lever 140Y, the third switching lever 140M, and the fourth switching lever 140C are in the transmitting position. At this time, all of the developer cartridges 60 in the image forming apparatus 1 are in the contact position, and the driving force from the first motor M1 can be transmitted to all of the developer rollers 61.

[0103] The rotating cam 120 is rotatable between a first cam position shown in Fig. 11 in which the corresponding cam follower 110 is positioned in a pressing position, and a second cam position shown in Fig. 15 in which the corresponding cam follower 110 is positioned in a non-pressing position. When the rotating cam 120 is positioned in the second cam position, the cam contact portion 115 of the cam follower 110 contacts a second holding surface 127 of the rotating cam 120 and is supported by the second holding surface 127. Furthermore, as shown in Fig. 11, when the rotating cam 120 is positioned in the first cam position, the cam contact portion 115 of the cam follower 110 contacts a first holding surface 125 of the rotating cam 120 and is supported by the first holding surface 125.

[0104] 10, the linear motion plate 200 has a first cam groove 210, a first lever groove 220, a second cam groove 230, a second lever groove 240, and a rack gear 250. The image forming apparatus 1 also includes a drive gear 260 rotatably supported by the housing 10.

[0105] The first cam groove 210 moves the first cam follower 110K between a pressing position and a non-pressing position due to the linear motion of the linear motion plate 200. A cam boss 124 of the first rotating cam 120K engages with the first cam groove 210. The first cam groove 210 has a vertical groove 211 extending vertically and a horizontal groove 212 extending rearward from the upper end of the vertical groove 211. The vertical groove 211 acts on the cam boss 124 of the first rotating cam 120K as the linear motion of the linear motion plate 200 occurs, causing the first rotating cam 120K to rotate between the first cam position and the second cam position. The horizontal groove 212 maintains the first rotating cam 120K in the second cam position.

[0106] The first lever groove 220 moves the first switching lever 140K between the disengagement position and the transmission position due to the linear movement of the linear motion plate 200. A lever boss 141C of the first switching lever 140K engages with the first lever groove 220. The first lever groove 220 has a vertically extending vertical groove 222, a horizontal groove 221 extending forward from the lower end of the vertical groove 222, and a horizontal groove 223 extending rearward from the upper end of the vertical groove 222. The horizontal groove 221 maintains the first switching lever 140K in the disengagement position. The vertical groove 222 acts on the lever boss 141C of the first switching lever 140K in accordance with the linear movement of the linear motion plate 200, causing the first switching lever 140K to rotate between the disengagement position and the transmission position. The horizontal groove 223 maintains the first switching lever 140K in the transmission position.

[0107] The linear motion plate 200 is provided to move the first switching lever 140K to the transmission position before the first cam follower 110K moves to the non-pressing position, and to move the first switching lever 140K to the disconnecting position after the first cam follower 110K moves to the pressing position. Specifically, the vertical groove 222 of the first lever groove 220 is disposed downstream of the vertical groove 211 of the first cam groove 210 in the direction in which the linear motion plate 200 moves from the first position to the second position. More specifically, the vertical groove 222 of the first lever groove 220 is disposed forward of the vertical groove 211 of the first cam groove 210.

[0108] The second cam grooves 230 move the cam followers 110Y, 110M, and 110C between a pressing position and a non-pressing position by linear motion of the linear motion plate 200. Three second cam grooves 230 are provided corresponding to the cam followers 110Y, 110M, and 110C. The second cam grooves 230 are engaged with the cam bosses 124 of the corresponding rotating cams 120Y, 120M, and 120C.

[0109] The second cam groove 230 has a vertical groove 232 extending vertically and a horizontal groove 231 extending forward from the lower end of the vertical groove 232. The horizontal groove 231 maintains the corresponding rotating cam 120Y, 120M, 120C at the first cam position. The vertical groove 232 acts on the cam boss 124 of the corresponding rotating cam 120Y, 120M, 120C as the linear motion of the linear motion plate 200 occurs, causing the rotating cam 120Y, 120M, 120C to rotate between the first cam position and the second cam position.

[0110] The second lever grooves 240 move the switching levers 140Y, 140M, 140C between the disconnection position and the transmission position by linear motion of the linear motion plate 200. Three second lever grooves 240 are provided corresponding to the switching levers 140Y, 140M, 140C. The second lever grooves 240 are engaged with the lever bosses 141C of the corresponding switching levers 140Y, 140M, 140C.

[0111] The second lever groove 240 has a vertical groove 242 extending vertically, a horizontal groove 241 extending forward from the lower end of the vertical groove 242, and a horizontal groove 243 extending rearward from the upper end of the vertical groove 242. The horizontal groove 241 maintains the corresponding switching lever 140Y, 140M, 140C in the disengaged position. The vertical groove 242 acts on the lever boss 141C of the corresponding switching lever 140Y, 140M, 140C in accordance with the linear movement of the linear motion plate 200, causing the switching lever 140Y, 140M, 140C to rotate between the disengaged position and the transmission position. The horizontal groove 243 maintains the corresponding switching lever 140Y, 140M, 140C in the transmission position.

[0112] The linear motion plate 200 is configured to move the second switching lever 140Y, the third switching lever 140M and the fourth switching lever 140C to the transmission position before the second cam follower 110Y, the third cam follower 110M and the fourth cam follower 110C move to the non-pressing position, and to move the second switching lever 140Y, the third switching lever 140M and the fourth switching lever 140C to the disconnecting position after the second cam follower 110Y, the third cam follower 110M and the fourth cam follower 110C move to the pressing position.

[0113] Specifically, the vertical groove 242 of the second lever groove 240 is disposed downstream of the vertical groove 232 of the second cam groove 230 in the direction in which the linear motion plate 200 moves from the first position to the second position. More specifically, the vertical groove 242 of the second lever groove 240 is disposed forward of the vertical groove 232 of the second cam groove 230.

[0114] The rack gear 250 is formed on the underside of the rear end portion of the linear motion plate 200. The rack gear 250 meshes with a drive gear 260. The drive gear 260 rotates when a driving force is input from the second motor M2. The second motor M2 is capable of rotating forward and backward. For example, when the second motor M2 rotates forward and the drive gear 260 rotates clockwise in FIG. 10, the linear motion plate 200 moves linearly from rear to front, and when the second motor M2 rotates reversely and the drive gear 260 rotates counterclockwise in FIG. 10, the linear motion plate 200 moves linearly from front to rear.

[0115] The control unit 2 includes a CPU, ROM, RAM, input / output units, etc., and performs control by executing pre-stored programs. The control unit 2 controls the driving and stopping of the motors M1 and M2. The control unit 2 also controls the rotation direction of the second motor M2 to linearly move the linear motion plate 200 back and forth, thereby controlling the contact and separation of the developing roller 61 with the corresponding photosensitive drum 50, and the driving and stopping of the developing roller 61.

[0116] Next, the operation of the image forming apparatus 1 of the first embodiment will be described. 11, when the linear motion plate 200 is in the first position, all of the cam followers 110 are in the pressing position, and all of the switching levers 140 are in the disengaging position. At this time, the cam boss 124 of the first cam follower 110K is located at the lower end of the vertical groove 211 of the first cam groove 210, and the lever boss 141C of the first switching lever 140K is located in the horizontal groove 221 of the first lever groove 220. In addition, the cam bosses 124 of the cam followers 110Y, 110M, and 110C are located in the horizontal groove 231 of the corresponding second cam groove 230, and the lever boss 141C of the switching levers 140Y, 140M, and 140C is located in the horizontal groove 241 of the corresponding second lever groove 240.

[0117] 11, the linear motion plate 200 moves linearly forward from the first position to the second position. Then, the cam boss 124 of the first rotating cam 120K is pushed forward by the wall of the vertical groove 211, and the first rotating cam 120K starts to rotate counterclockwise in FIG. 11 from the first cam position.

[0118] While the first switching lever 140K remains in the disengaged position, the lever boss 141C moves relative to the lower end of the vertical groove 222 of the first lever groove 220. Then, the lever boss 141C is pushed forward by the wall of the vertical groove 222, causing the first switching lever 140K to swing from the disengaged position to the transmission position as shown in FIG. 12. At this time, the biasing force of the tension coil spring 144 also acts, ensuring that the first switching lever 140K swings from the disengaged position to the transmission position. This causes the tip 142C to engage with the claw portion 168 of the transmission element 160D of the clutch 160K, transmitting the driving force from the first motor M1 to the first developing cartridge 60K and starting to drive the first developing roller 61K.

[0119] As the first rotating cam 120K rotates, the surface that contacts the cam contact portion 115 of the first cam follower 110K switches from the first holding surface 125 to the first cam surface 126, and the first cam surface 126 causes the first cam follower 110K to slide from the pressing position toward the non-pressing position.

[0120] 13, when the linear motion plate 200 is located at the third position, the first rotating cam 120K rotates to the second cam position, the surface of the first cam follower 110K that contacts the cam contact portion 115 switches from the first cam surface 126 to the second holding surface 127, and the first cam follower 110K is located at the non-pressing position. As a result, the first developing cartridge 60K is located at the contact position, and the first developing roller 61K contacts the first photosensitive drum 50K.

[0121] While the linear motion plate 200 moves from the first position to the third position, the rotating cams 120Y, 120M, 120C do not rotate and are maintained at the first cam position because the cam boss 124 moves relatively in the lateral groove 231 of the second cam groove 230. Furthermore, the switching levers 140Y, 140M, 140C do not swing and are maintained at the disconnection position because the lever boss 141C moves relatively in the lateral groove 241 of the second lever groove 240.

[0122] When the linear motion plate 200 stops at the third position, printing can be performed using only the first black developing roller 61K.

[0123] When the linear motion plate 200 moves further forward linearly from the third position toward the second position, the cam bosses 124 of the rotating cams 120Y, 120M, 120C move relative to the lower ends of the vertical grooves 232 of the second cam grooves 230. Then, the cam bosses 124 are pushed forward by the walls of the vertical grooves 232, causing the rotating cams 120Y, 120M, 120C to start rotating counterclockwise in FIG. 13 from the first cam position.

[0124] Furthermore, the lever boss 141C of the switching levers 140Y, 140M, and 140C moves relative to the lower end of the vertical groove 242 of the second lever groove 240. Then, the lever boss 141C is pushed forward by the wall of the vertical groove 242, causing the switching levers 140Y, 140M, and 140C to swing from the disengagement position to the transmission position as shown in FIG. 14. At this time, the biasing force of the tension coil spring 144 also acts, ensuring that the switching levers 140Y, 140M, and 140C swing from the disengagement position to the transmission position. As a result, the tip 142C engages with the claw portion 168 of the transmission element 160D of the corresponding clutch 160Y, 160M, and 160C, and the driving force from the first motor M1 is transmitted to the developer cartridges 60Y, 60M, and 60C, causing the developing rollers 61Y, 61M, and 61C to start driving.

[0125] When the rotating cams 120Y, 120M, 120C rotate, the surface that contacts the cam contact portion 115 of the corresponding cam follower 110Y, 110M, 110C switches from the first holding surface 125 to the first cam surface 126, and the first cam surface 126 slides the corresponding cam follower 110Y, 110M, 110C from the pressed position toward the non-pressed position.

[0126] 15, when the linear motion plate 200 is located at the second position, the rotating cams 120Y, 120M, 120C rotate to the second cam position, the surfaces of the corresponding cam followers 110Y, 110M, 110C that contact the cam contact portions 115 change from the first cam surfaces 126 to the second holding surfaces 127, and the cam followers 110Y, 110M, 110C are located at the non-pressing positions. As a result, the developing cartridges 60Y, 60M, 60C are located at the contact positions, and the developing rollers 61Y, 61M, 61C contact the corresponding photosensitive drums 50Y, 50M, 50C.

[0127] When the linear motion plate 200 is located at the second position, printing can be performed using all of the developing rollers 61.

[0128] When the drive gear 260 rotates counterclockwise in Fig. 15, the linear motion plate 200 moves linearly backward from the second position to the first position. Then, the cam bosses 124 of the rotating cams 120Y, 120M, 120C are pushed backward by the wall of the vertical groove 232 of the second cam groove 230, causing the rotating cams 120Y, 120M, 120C to start rotating clockwise in Fig. 15 from the second cam position. The lever boss 141C moves relatively along the horizontal groove 243 of the second lever groove 240, so that the switching levers 140Y, 140M, 140C do not swing and are maintained in the transmission position.

[0129] The cam followers 110Y, 110M, and 110C slide from the non-pressing position to the pressing position as the corresponding rotating cams 120Y, 120M, and 120C rotate, and press the corresponding developer cartridges 60Y, 60M, and 60C, thereby separating the developer rollers 61Y, 61M, and 61C from the corresponding photosensitive drums 50Y, 50M, and 50C.

[0130] 14, when the developing rollers 61Y, 61M, 61C are separated from the corresponding photosensitive drums 50Y, 50M, 50C, the lever bosses 141C of the switching levers 140Y, 140M, 140C move relative to the upper end of the vertical groove 242 of the second lever groove 240. Then, the lever boss 141C is pushed rearward by the wall of the vertical groove 242, causing the switching levers 140Y, 140M, 140C to swing from the transmission position to the disengagement position against the biasing force of the tension coil spring 144. As a result, the tip ends 142C are disengaged from the transmission elements 160D of the corresponding clutches 160Y, 160M, 160C, and the driving force from the first motor M1 is no longer transmitted to the developing cartridges 60Y, 60M, 60C, causing the developing rollers 61Y, 61M, 61C to stop.

[0131] As shown in FIG. 13, when the linear motion plate 200 is located at the third position, the cam contact portions 115 of the cam followers 110Y, 110M, 110C come into contact with the first holding surfaces 125 of the corresponding rotating cams 120Y, 120M, 120C. While the linear motion plate 200 moves from the second position to the third position, the first rotating cam 120K does not rotate and is maintained at the second cam position because the cam boss 124 moves relatively along the lateral groove 212 of the first cam groove 210. Furthermore, the first switching lever 140K does not swing and is maintained at the disconnection position because the lever boss 141C moves relatively along the lateral groove 223 of the first lever groove 220.

[0132] When the linear motion plate 200 moves further linearly backward from the third position toward the first position, the cam boss 124 of the first rotating cam 120K moves relatively to the upper end of the vertical groove 211 of the first cam groove 210. Then, the cam boss 124 is pushed backward by the wall of the vertical groove 211, causing the first rotating cam 120K to start rotating clockwise in Figure 13 from the first cam position. The first switching lever 140K does not swing because the lever boss 141C moves relatively in the horizontal groove 223 of the first lever groove 220, and is maintained in the transmission position.

[0133] The first cam follower 110K slides from the non-pressing position to the pressing position due to the rotation of the first rotating cam 120K, and presses the first developing cartridge 60K, thereby separating the first developing roller 61K from the first photosensitive drum 50K.

[0134] When the first developing roller 61K separates from the first photosensitive drum 50K, as shown in FIG. 12, the lever boss 141C of the first switching lever 140K moves relative to the upper end of the vertical groove 222 of the first lever groove 220. Then, the lever boss 141C is pushed rearward by the wall of the vertical groove 222, causing the first switching lever 140K to swing from the transmission position to the disengagement position against the biasing force of the tension coil spring 144. As a result, the tip 142C disengages from the transmission element 160D of the clutch 160K, and the driving force from the first motor M1 is no longer transmitted to the first developing cartridge 60K, causing the first developing roller 61K to stop. Then, as shown in FIG. 11, when the linear motion plate 200 is positioned in the first position, the cam contact portion 115 of the first cam follower 110K comes into contact with the first holding surface 125 of the first rotating cam 120K.

[0135] According to the first embodiment described above, the mechanism for controlling the contact and separation of the developing roller 61 and the drive and stop of the developing roller 61 can be made compact. For example, if a cam surface for sliding the cam follower is provided on a rotating cam, the diameter of the cam would increase, and it would be necessary to provide a gear train or an electromagnetic clutch for transmitting the drive force from the motor to the cam, which would limit how compact the mechanism can be. In a configuration using the linear motion plate 200 as in the first embodiment, for example, the rotating cam 120 does not need to rotate once, so a space-saving configuration is possible, and it is not necessary to provide a gear train or an electromagnetic clutch for transmitting the drive force from the motor to the rotating cam 120. Therefore, the mechanism for controlling the contact and separation of the developing roller 61 and the drive and stop of the developing roller 61 can be made compact.

[0136] Furthermore, since the compression coil spring 150 is provided to bias the cam follower 110 toward the non-pressing position, the cam follower 110 can be reliably positioned at the non-pressing position when the linear motion plate 200 is positioned at the second position.

[0137] Furthermore, since the corresponding switching lever 140 is moved to the transmission position at a timing before the cam follower 110 moves to the non-pressing position, the developing roller 61 can be rotated before contacting the corresponding photosensitive drum 50. Furthermore, since the corresponding switching lever 140 is moved to the disconnecting position at a timing after the cam follower 110 moves to the pressing position, the developing roller 61 can be stopped after being separated from the corresponding photosensitive drum 50.

[0138] Furthermore, since the second lever 142 of the switching lever 140 can swing relative to the first lever 141 against the biasing force of the torsion spring 143, even if the tip 142C of the second lever 142 is repelled when engaging with the claw portion 168 of the rotating transmission element 160D, excessive force is not applied to the switching lever 140.

[0139] Furthermore, since the first lever 141 is provided with the first protrusion 141E and the second protrusion 141F, the swing range of the second lever 142 can be determined by the first protrusion 141E and the second protrusion 141F.

[0140] Furthermore, since the tension coil spring 144 is provided to bias the switching lever 140 toward the transmission position, the switching lever 140 can be reliably positioned at the transmission position when the linear motion plate 200 is positioned at the second position.

[0141] Furthermore, when the linear motion plate 200 is located at the first position, all of the developing rollers 61 are separated from the corresponding photosensitive drums 50, when the linear motion plate 200 is located at the third position, only the first developing roller 61K is in contact with the first photosensitive drum 50K, and when the linear motion plate 200 is located at the second position, all of the developing rollers 61 are in contact with the corresponding photosensitive drums 50. This makes it possible to switch, for example, between a mode in which all of the developing rollers 61 are separated from the corresponding photosensitive drums 50, a mode in which printing is performed using only the first developing roller 61K, and a mode in which printing is performed using all of the developing rollers 61.

[0142] Next, a second embodiment will be described. Note that, below, differences from the first embodiment will be described, and explanations of the same points will be omitted as appropriate, for example, by assigning the same reference numerals to similar elements. 16, the image forming apparatus 1 includes a cam follower 110, a compression coil spring 150, a linear motion plate 200, and a frame 300. The image forming apparatus 1 of the second embodiment does not include a rotating cam.

[0143] Cam follower 110 (first cam follower 110K, second cam follower 110Y, third cam follower 110M, and fourth cam follower 110C) has a pin 111 and a first flange portion 112 extending from the outer circumferential surface of pin 111 toward the outside in the radial direction of pin 111.

[0144] The linear motion plate 200 has a first plate portion 201, a second plate portion 202, a third plate portion 203, and a fourth plate portion 204. The first plate portion 201 extends from the upper end of the second plate portion 202 toward one side in the rotational axis direction. The second plate portion 202 has a long hole 205 that is long in the front-to-rear direction for passing the four first shafts 119. The third plate portion 203 extends from the lower end of the second plate portion 202 toward one side in the rotational axis direction and is connected to the upper end of the fourth plate portion 204. The fourth plate portion 204 is located at a different position from the second plate portion 202 in the rotational axis direction. Specifically, the fourth plate portion 204 is located closer to the frame 300 than the second plate portion 202 in the rotational axis direction. The fourth plate portion 204 has a first lever groove 220 , three second lever grooves 240 , and a rack gear 250 .

[0145] As shown in FIG. 17, the linear motion plate 200 further includes a second cam portion 270 and a third cam portion 280. The second cam portion 270 is provided corresponding to the first cam follower 110K, and has a rib shape that protrudes to one side in the rotation axis direction from the upper and lower portions of the elongated hole 205 of the second plate portion 202. The second cam portion 270 has a second cam surface 271 and a holding surface 272.

[0146] The holding surface 272 is an end surface on one side in the rotational axis direction of the second cam portion 270, and holds the first cam follower 110K in the pressing position. The holding surface 272 is approximately perpendicular to the rotational axis direction. The second cam surface 271 slides the first cam follower 110K between the pressing position and the non-pressing position due to the linear motion of the linear motion plate 200. The second cam surface 271 is capable of coming into contact with the first cam follower 110K and is inclined with respect to the movement direction of the linear motion plate 200. Specifically, the second cam surface 271 is inclined so as to approach the first developing cartridge 60K (the front side in FIG. 17) from the rear to the front.

[0147] Three third cam portions 280 are provided corresponding to second cam follower 110Y, third cam follower 110M, and fourth cam follower 110C, and have a rib shape that protrudes to one side in the rotation axis direction from upper and lower portions of elongated hole 205 of second plate portion 202. In the movement direction (front-rear direction) of linear motion plate 200, the length of third cam portion 280 is longer than the length of second cam portion 270. Third cam portion 280 has a third cam surface 281 and a holding surface 282.

[0148] The holding surface 282 is an end surface on one side in the rotational axis direction of the third cam portion 280, and holds the corresponding cam followers 110Y, 110M, 110C in the pressing position. The holding surface 282 is approximately perpendicular to the rotational axis direction. In the movement direction (front-rear direction) of the linear motion plate 200, the length of the holding surface 282 is longer than the length of the holding surface 272.

[0149] The third cam surfaces 281 slide the corresponding cam followers 110Y, 110M, 110C between a pressing position and a non-pressing position due to the linear motion of the linear motion plate 200. The third cam surfaces 281 are capable of coming into contact with the corresponding cam followers 110Y, 110M, 110C, and are inclined with respect to the movement direction of the linear motion plate 200. Specifically, the third cam surfaces 281 are inclined so as to approach the corresponding developer cartridges 60Y, 60M, 60C (the front side in FIG. 17) from the rear to the front.

[0150] As shown in FIG. 18(a), when cam follower 110 is located in the pressing position, first flange portion 112 comes into contact with holding surfaces 272, 282 of the corresponding cam portions 270, 280. Also, as shown in FIG. 18(b), when cam follower 110 is located in the non-pressing position, first flange portion 112 does not come into contact with the corresponding cam portions 270, 280. When cam follower 110 is located in the non-pressing position, first flange portion 112 comes into contact with an end face on one side in the rotational axis direction of second plate portion 202. Cam follower 110 is biased toward the non-pressing position by compression coil spring 150.

[0151] Next, the operation of the image forming apparatus 1 of the second embodiment will be described. Note that in Figures 19(a), 20(a) and 21(a), the holding surfaces 272, 282 of the cam portions 270, 280 are indicated by dot hatching. As shown in FIG. 19, when the linear motion plate 200 is located at the first position, all the cam followers 110 are located at the pressing position, and all the switching levers 140 are located at the disconnecting position.

[0152] 19 to the third position shown in Fig. 20, the first lever groove 220 causes the first switching lever 140K to swing from the disconnection position to the transmission position, and the tip 142C engages with the claw portion 168 (transmission element 160D) of the clutch 160K. As a result, the driving force from the first motor M1 is transmitted to the first developing cartridge 60K, and the first developing roller 61K begins to drive.

[0153] The surface of the first cam follower 110K that comes into contact with the first flange portion 112 switches from the holding surface 272 of the second cam portion 270 to the second cam surface 271, and the first cam follower 110K slides from the pressing position to the non-pressing position due to the second cam surface 271. Then, when the first flange portion 112 is no longer in contact with the second cam surface 271 (second cam portion 270) and comes into contact with the second plate portion 202, the first cam follower 110K is positioned at the non-pressing position. As a result, the first developing cartridge 60K is positioned at the contact position, and the first developing roller 61K comes into contact with the first photosensitive drum 50K.

[0154] While the linear motion plate 200 moves from the first position to the third position, the switching levers 140Y, 140M, and 140C are maintained in the disconnecting position. Also, the first flange portion 112 of the cam follower 110Y, 110M, and 110C continues to contact the holding surface 282 of the third cam portion 280, so that the cam follower 110Y, 110M, and 110C does not slide and is maintained in the pressing position.

[0155] 21, the second lever groove 240 causes the switching levers 140Y, 140M, and 140C to swing from the disconnection position to the transmission position, and the tips 142C engage with the pawl portions 168 (transmission elements 160D) of the corresponding clutches 160Y, 160M, and 160C. As a result, the driving force from the first motor M1 is transmitted to the developer cartridges 60Y, 60M, and 60C, and the developing rollers 61Y, 61M, and 61C begin to drive.

[0156] The surface of the cam follower 110Y, 110M, 110C that comes into contact with the first flange portion 112 switches from the holding surface 282 of the corresponding third cam portion 280 to the third cam surface 281, and the cam follower 110Y, 110M, 110C slides from the pressing position to the non-pressing position due to the third cam surface 281. Then, when the first flange portion 112 of the cam follower 110Y, 110M, 110C is no longer in contact with the third cam surface 281 (third cam portion 280) and comes into contact with the second plate portion 202, the cam follower 110Y, 110M, 110C is positioned at the non-pressing position. As a result, the developer cartridges 60Y, 60M, 60C are positioned at the contact position, and the developer rollers 61Y, 61M, 61C come into contact with the corresponding photosensitive drums 50Y, 50M, 50C.

[0157] As shown in FIG. 21, when the linear motion plate 200 is in the second position, all the cam followers 110 are in the non-pressing position, and all the switching levers 140 are in the transmitting position.

[0158] 20, the second lever groove 240 causes the switching levers 140Y, 140M, and 140C to swing from the transmission position to the disconnection position, and the tip ends 142C are disengaged from the transmission elements 160D of the corresponding clutches 160Y, 160M, and 160C. As a result, the driving force from the first motor M1 is no longer transmitted to the developer cartridges 60Y, 60M, and 60C, and the developer rollers 61Y, 61M, and 61C stop.

[0159] The first flange portions 112 of the cam followers 110Y, 110M, and 110C come into contact with the third cam surfaces 281 of the corresponding third cam portion 280, and the cam followers 110Y, 110M, and 110C slide from the non-pressing position toward the pressing position due to the third cam surfaces 281. The cam followers 110Y, 110M, and 110C are then positioned at the pressing position when the surface with which the first flange portions 112 come into contact switches from the third cam surface 281 to the holding surface 282. As a result, the developer cartridges 60Y, 60M, and 60C are positioned at the separated position, and the developer rollers 61Y, 61M, and 61C are separated from the corresponding photosensitive drums 50Y, 50M, and 50C.

[0160] While the linear motion plate 200 moves from the second position to the third position, the first switching lever 140K is maintained in the transmission position. Also, the first cam follower 110K does not slide because the first flange portion 112 does not contact the second cam portion 270 and remains in contact with the second plate portion 202, and is maintained in the non-pressing position.

[0161] 19, the first lever groove 220 causes the first switching lever 140K to swing from the transmission position to the disconnection position, and the tip 142C disengages from the transmission element 160D of the clutch 160K. As a result, the driving force from the first motor M1 is no longer transmitted to the first developing cartridge 60K, and the first developing roller 61K stops.

[0162] The first cam follower 110K has its first flange portion 112 contacting the second cam surface 271 of the second cam portion 270, and is slid by the second cam surface 271 from the non-pressing position to the pressing position. The first cam follower 110K is then positioned at the pressing position when the surface with which the first flange portion 112 contacts switches from the second cam surface 271 to the holding surface 272. This positions the first developing cartridge 60K at the separated position, and the first developing roller 61K is separated from the first photosensitive drum 50K.

[0163] According to the second embodiment described above, similarly to the first embodiment, it is possible to make compact the mechanism for controlling the contact and separation of the developing roller 61 and the drive and stop of the developing roller 61. In particular, in the second embodiment, a rotating cam is not provided, and the cam follower 110 is slid directly by the linear motion plate 200, so that it is possible to make the mechanism for controlling the contact and separation of the developing roller 61 and the drive and stop of the developing roller 61 even more compact.

[0164] Although the embodiment has been described above, the image forming apparatus can be modified as appropriate as exemplified below.

[0165] In the above embodiment, the compression coil spring 150 is exemplified as the first spring that biases the cam follower toward the non-pressing position, but the first spring may be a spring other than a compression coil spring as long as it has the same function. The same applies to the second spring and the third spring. Furthermore, the image forming apparatus may be configured without the third spring, for example.

[0166] In the above embodiment, the first lever 141 of the switching lever 140 is provided with the second protrusion 141F for defining the swing range of the second lever 142, but for example, the first lever may not be provided with the second protrusion. Also, in the above embodiment, the switching lever 140 has the first lever 141 and the second lever 142, and the second lever 142 is swingable relative to the first lever 141, but for example, the switching lever may be a member in which the first lever 141 and the second lever 142 of the above embodiment are integrally molded.

[0167] In the above embodiment, the linear motion plate 200 is configured to be linearly movable between the first position and the second position via the third position, but for example, the linear motion plate may be configured to be linearly movable only between the first position and the second position. In this case, for example, when the linear motion plate is located at the first position, all the cam followers may be located at the pressing position and all the switching levers may be located at the disconnecting position, and when the linear motion plate is located at the second position, all the cam followers may be located at the non-pressing position and all the switching levers may be located at the transmitting position.

[0168] The linear motion plate may be configured to be able to move linearly between the first position and the second position via a third position and a fourth position that is a position between the third position and the second position. Furthermore, the linear motion plate may be configured to be able to move linearly between the first position and the second position via the third position, the fourth position, and a fifth position that is a position between the fourth position and the second position. In this case, for example, when the linear plate is located at the first position, four cam followers are located at the pressing position and four switching levers are located at the disconnecting position; when the linear plate is located at the third position, one cam follower is located at the non-pressing position and one corresponding switching lever is located at the transmission position; when the linear plate is located at the fourth position, two cam followers are located at the non-pressing position and two corresponding switching levers are located at the transmission position; when the linear plate is located at the fifth position, three cam followers are located at the non-pressing position and three corresponding switching levers are located at the transmission position; and when the linear plate is located at the second position, four cam followers are located at the non-pressing position and four switching levers are located at the transmission position.

[0169] In the embodiment described above, the image forming apparatus 1 is a color printer having a plurality of photosensitive drums 50 and a corresponding plurality of developing cartridges 60, cam followers 110, and switching levers 140. However, for example, the image forming apparatus may be a monochrome printer having only one photosensitive drum and one developing cartridge, one cam follower, and one switching lever. Also, for example, the image forming apparatus may be a copying machine, a multifunction machine, or the like.

[0170] The elements described in the above-described embodiment and modified examples may be implemented in any combination. [Explanation of symbols]

[0171] 1. Image forming device 50K 1st photosensitive drum 60K 1st Developer Cartridge 61K First developing roller 110K 1st cam follower 140K First switching lever 200 Linear motion plate M1 First motor

Claims

1. An image forming apparatus including a first photosensitive drum, A motor; a first developing cartridge having a first developing roller, the first developing cartridge being movable between a contact position where the first developing roller contacts the first photosensitive drum and a separation position where the first developing roller is separated from the first photosensitive drum; a first cam follower that is slidable in a direction of the rotation axis of the first developing roller between a pressing position where the first developing cartridge is pressed against the first developing cartridge to position the first developing cartridge at the separated position and a non-pressing position where the first developing cartridge is positioned at the contact position; a first switching lever movable between a transmission position where the driving force from the motor can be transmitted to the first developing roller and a disconnection position where the driving force from the motor is not transmitted to the first developing roller; a linear motion plate that is linearly movable in a direction perpendicular to the rotation axis direction between a first position and a second position, and that linearly moves the first cam follower between the pressing position and the non-pressing position and moves the first switch lever between the transmission position and the disconnection position, When the linear motion plate is located at the first position, the first cam follower is located at the pressing position and the first switching lever is located at the disconnecting position, an image forming apparatus, wherein when the linear motion plate is located at the second position, the first cam follower is located at the non-pressing position and the first switching lever is located at the transmitting position;

2. a rotary cam that rotates in conjunction with the linear motion of the linear motion plate; 2. The image forming apparatus according to claim 1, wherein the rotating cam has a first cam surface that is capable of contacting the first cam follower and is inclined with respect to the movement direction of the first cam follower, and that causes the first cam follower to slide between the pressing position and the non-pressing position upon rotation of the rotating cam.

3. 2. The image forming apparatus according to claim 1, wherein the linear plate has a second cam surface that is capable of contacting the first cam follower and is inclined with respect to the direction of movement of the linear plate, and the second cam surface causes the first cam follower to slide between the pressing position and the non-pressing position due to the linear movement of the linear plate.

4. 4. The image forming apparatus according to claim 2, further comprising a first spring that biases the first cam follower toward the non-pressing position.

5. 5. The image forming apparatus according to claim 1, wherein the linear plate is configured to move the first switching lever to the transmission position before the first cam follower moves to the non-pressing position, and to move the first switching lever to the cutting position after the first cam follower moves to the pressing position.

6. a clutch that includes a planetary gear mechanism including a sun gear, a ring gear, a carrier, and planetary gears, and that is switchable between a transmission state in which the driving force from the motor can be transmitted to the first developing roller and a disconnection state in which the driving force from the motor is not transmitted to the first developing roller; 6. An image forming apparatus according to claim 1, wherein when the first switching lever is located in the transmission position, it engages with one element having one of the sun gear, the ring gear, and the carrier of the planetary gear mechanism to place the clutch in the transmission state, and when the first switching lever is located in the disengagement position, it disengages from the one element to place the clutch in the disengagement state.

7. the first switching lever is swingable around a swing shaft between the transmission position and the disconnection position, a first lever that is swingable around the swing shaft and swings in conjunction with the linear motion of the linear motion plate; a second lever that is swingable around the swing shaft, the second lever having a tip that is engageable with the one element when the first switching lever is located at the transmission position and that disengages from the one element when the first switching lever is located at the disconnection position; a first protrusion provided on the first lever, the first protrusion restricting the swing of the second lever in a direction in which the tip of the second lever approaches the one element; a second spring that biases the second lever toward the first lever in a direction that brings the second lever into contact with the first protrusion; and 7. The image forming apparatus according to claim 6, wherein the second lever is capable of swinging relative to the first lever against the biasing force of the second spring.

8. The image forming apparatus according to claim 7, characterized in that the first lever is provided with a second protrusion that restricts the swinging of the second lever by contacting the second lever when the second lever swings a predetermined amount relative to the first lever against the biasing force of the second spring.

9. 9. The image forming apparatus according to claim 1, further comprising a third spring that biases the first switching lever toward the transmission position.

10. A second photosensitive drum; a second developing cartridge having a second developing roller, the second developing cartridge being movable between a contact position where the second developing roller contacts the second photosensitive drum and a separation position where the second developing roller is separated from the second photosensitive drum; a second cam follower that is slidable in the direction of the rotation axis between a pressing position where the second developer cartridge is pressed to position the second developer cartridge at the separated position and a non-pressing position where the second developer cartridge is positioned at the contact position; a second switching lever that is movable between a transmission position where the driving force from the motor can be transmitted to the second developing roller and a disconnection position where the driving force from the motor is not transmitted to the second developing roller, the linear motion plate is linearly movable between the first position and the second position via a third position which is a position between the first position and the second position, and is configured to move the second cam follower between the pressing position and the non-pressing position and move the second switch lever between the transmission position and the disconnection position by linear motion, When the linear motion plate is located at the first position, the second cam follower is located at the pressing position and the second switching lever is located at the disconnecting position, When the linear motion plate is located at the second position, the second cam follower is located at the non-pressing position and the second switching lever is located at the transmitting position, 10. The image forming apparatus according to claim 1, wherein, when the linear plate is located at the third position, the first cam follower is located at the non-pressing position, the first switching lever is located at the transmitting position, the second cam follower is located at the pressing position, and the second switching lever is located at the disconnecting position.

11. 11. The image forming apparatus according to claim 10, wherein the linear motion plate is configured to move the second switching lever to the transmission position before the second cam follower moves to the non-pressing position, and to move the second switching lever to the cutting position after the second cam follower moves to the pressing position.

12. 12. The image forming apparatus according to claim 1, wherein the first cam follower has a pin that extends in the direction of the rotation axis and presses the first developing cartridge.

Images