JP7794028B2 - Image forming device - Google Patents

Description

The present invention relates to an image forming apparatus equipped with a photosensitive drum and a developing roller.

Conventionally, an image forming device is known that includes a photosensitive drum, a developer cartridge having a developer roller, a rotating cam, and a cam follower that can slide in the direction of the rotational axis of the developer roller as the cam rotates (Patent Document 1). With this technology, the cam rotates to slide the cam follower, causing the cam follower to press against the developer cartridge, thereby moving the developer roller from a position in contact with the photosensitive drum to a position separated from the photosensitive drum.

This technology also includes a clutch that has a planetary gear mechanism and 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 place the clutch in a transmission state and a position in which it disengages from the element to place the clutch in a disconnection state. The transmission and disconnection of the driving force to the developing roller are switched by rotating a cam to swing the lever.

Japanese Patent Application Laid-Open No. 2021-015149

However, as image forming devices become smaller, there is a demand for more compact mechanisms for controlling the contact and separation of the developing roller, as well as the driving and stopping of the developing roller.

The objective is to provide an image forming device that can compactly control the contact and separation of the developing roller, as well as the driving and stopping of the developing roller.

an image forming apparatus having a first photosensitive drum, the apparatus 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 at 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 the 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.

This configuration allows for a compact mechanism for controlling the contact and separation of the developing roller, as well as the driving and stopping of the developing roller.

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 relative to the direction of movement of the first cam follower, and which causes the first cam follower to slide between a pressed position and a non-pressed position as the rotating cam rotates.

The linear motion plate may also have a second cam surface that is capable of contacting the first cam follower and is inclined relative to the direction of movement of the linear motion plate, and that causes the first cam follower to slide between the pressing position and the non-pressing position due to the linear motion of the linear motion plate.

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

This allows the first cam follower to be reliably positioned in the non-pressing position when the linear plate is positioned in the second position.

The linear motion plate may also 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 disconnection position after the first cam follower moves to the pressing position.

This allows the first developing roller to rotate before coming into contact with the first photosensitive drum and to stop after it separates from the first photosensitive drum.

The image forming device may also have a planetary gear mechanism including a sun gear, a ring gear, a carrier, and planetary gears, 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 in the transmission position, it engages with one element including the sun gear, ring gear, or carrier of the planetary gear mechanism to place the clutch in the transmission state, and when it is in the disconnection position, it disengages from the one element to place the clutch in the disconnection state.

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 motion 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 biases 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 biasing force of the second spring.

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.

The first lever may also be provided with a second protrusion that restricts the swing 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.

This allows the first and second protrusions to define the swing range of the second lever.

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

This allows the first switching lever to be reliably positioned in the transmission position when the linear plate is positioned in the second position.

The image forming device 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 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 developing cartridge is pressed to position the second developing cartridge in the separation position and a non-pressing position where the second developing cartridge is positioned in the contact position; and 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, and the linear motion plate is movable between a first position and a second position. The linear motion plate may be linearly movable between the first and second positions via a third position which is between the first and second positions, and may be configured to move the second cam follower between the pressing position and the non-pressing position and move the second switching lever between the transmission position and the disconnection position by linear motion; when the linear motion plate is in the first position, the second cam follower is in the pressing position and the second switching lever is in the disconnection position; when the linear motion plate is in the second position, the second cam follower is in the non-pressing position and the second switching lever is in the transmission position; and when the linear motion plate is in the third position, the first cam follower is in the non-pressing position, the first switching lever is in the transmission position, the second cam follower is in the pressing position, and the second switching lever is in the disconnection position.

This allows all developing rollers to be separated from their corresponding photosensitive drums when the linear moving plate is in the first position, only the first developing roller to be in contact with the first photosensitive drum when the linear moving plate is in the third position, and all developing rollers to be in contact with their corresponding photosensitive drums when the linear moving plate is in the second position.

The linear motion plate may also 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 disconnection position after the second cam follower moves to the pressing position.

This allows the second developing roller to rotate before coming into contact with the second photosensitive drum and to stop after it separates from the second photosensitive drum.

The first cam follower may also be configured to have a pin that extends in the direction of the rotation axis and presses against the first developing cartridge.

The image forming device described above allows for a compact mechanism for controlling the contact and separation of the developing roller, as well as the driving and stopping of the developing roller.

FIG. 1 is a diagram illustrating a schematic configuration of an image forming apparatus. FIG. 2 is a side view showing a cam follower, a rotary cam, a developing drive gear train, a switching lever, a linear motion plate, and a frame according to the first embodiment. FIG. 2 is a perspective view showing a cam follower, a rotating cam, a compression coil spring, a first shaft, and a frame. 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. 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 of a cam follower as viewed from the cam follower side. 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 the cam follower is in a pressing position and FIG. 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. 4A and 4B are side views of a switching lever, an input gear, a clutch, and an output gear, in which FIG. 4A shows the switching lever in a disengaged position, and FIG. 4B shows the switching lever in a transmitted position. 1A is an exploded oblique view of the switching lever, FIG. 1B is a diagram showing a state in which the swing of the second lever is restricted by the first protrusion, and FIG. 1C is a diagram showing a state in which the swing of the second lever is restricted by the second protrusion. FIG. 2 is a side view showing the cam follower, the rotary cam, the switching lever, the linear motion plate, and the frame. 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. 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. 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. 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. 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. 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. 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. 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 in a non-pressing position. 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. 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. 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.

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.

The sheet supply unit 20 includes a sheet tray 21 on which 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. After being fed by the pickup roller 23, the sheets S in the sheet tray 21 are separated one by one between the separation roller 24 and the separation pad 25, and then supplied to the image forming unit 30 by the conveyance roller 26 and the registration roller 27.

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 to light.

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 transport direction of the sheet S (hereinafter simply referred to as the "transport direction"). The fourth photosensitive drum 50C is disposed downstream of the third photosensitive drum 50M in the transport direction. The first photosensitive drum 50K is disposed downstream of the fourth photosensitive drum 50C in the transport direction. In other words, 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 upstream to downstream in the transport direction.

In this specification and drawings, when describing components corresponding to each color, the Y, M, C, and K symbols are used, and when describing components without distinguishing between colors, the Y, M, C, and K symbols are not used.

A developing cartridge 60 is provided corresponding to each photosensitive drum 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.

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

More specifically, the first developing cartridge 60K is movable between a contact position where the first developing roller 61K contacts 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 contacts the second photosensitive drum 50Y and a separated position where the second developing roller 61Y is separated from the second photosensitive drum 50Y.

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

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 for each photosensitive drum 50. The drawer 55 detachably supports multiple developer cartridges 60. The drawer 55 can be attached to and detached from the housing 10 through an opening 10A in the housing 10 that is exposed by opening the front cover 11.

The transfer unit 70 comprises 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, with its outer surface in contact with each photosensitive drum 50. The transfer rollers 74 are positioned inside the conveyor belt 73, sandwiching the conveyor belt 73 between themselves and the corresponding photosensitive drum 50.

The fixing unit 80 includes a heating roller 81 and a pressure roller 82 positioned opposite the heating roller 81. Downstream of the fixing unit 80 in the conveying direction, a conveying roller 15 and a discharge roller 16 are provided.

In the image forming unit 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. This forms an electrostatic latent image based on the image data 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 the contact position, to the electrostatic latent image formed on the photosensitive drum 50. This forms a toner image on the photosensitive drum 50.

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

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".

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"). Specifically, 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 developer cartridge 60 to position the developer cartridge 60 in the separated position, and a non-pressing position shown in FIG. 4(b), where it positions the developer cartridge 60 in the contact position.

As shown in Figures 4(a) and (b), the developer cartridge 60 is supported in the drawer 55 so that it can move back and forth. The drawer 55 has a contact portion 55A and a pressing member 55B. The contact portion 55A is the portion that contacts the slide member 66 (described below), and consists of a roller that can rotate around an axis that runs vertically. 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, moving it to a contact position where the development roller 61 contacts the photosensitive drum 50.

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

The first abutment member 66B has a pressing surface 66D and a sloped surface 66E inclined relative to the axial direction, while the second abutment member 66C has a sloped surface 66F inclined similarly to the sloped 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 sloped surfaces 66E and 66F abut against the contacted portion 55A, urging the developer cartridge 60 in a direction perpendicular to the rotational axis, moving the developer roller 61 to a separated position where it is separated from the photosensitive drum 50. A spring 67 is disposed between the first abutment member 66B and the case 65, urging the slide member 66 to the left.

Returning to Figure 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.

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 it in the separated position, and a non-pressing position where it positions the first developer cartridge 60K in 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 it in the separated position, and a non-pressing position where it positions the second developer cartridge 60Y in the contact position.

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 in the separated position, and a non-pressing position where it positions the third developer cartridge 60M in 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 in the separated position, and a non-pressing position where it positions the fourth developer cartridge 60C in the contact position.

As shown in Figures 5(a) and (b), the cam followers 110 (first cam follower 110K, second cam follower 110Y, third cam follower 110M, and fourth cam follower 110C) have 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 restriction portion 116.

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.

The image forming device 1 is equipped with 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, one for each cam follower 110 (see Figure 3). The pin 111 engages with the first shaft 119, and is supported so as to be slidable in the direction of the rotation axis relative to the housing 10. This allows the cam follower 110 to slide in the direction of the rotation axis between a pressed position and a non-pressed position.

The first flange portion 112 extends from the outer peripheral surface of the pin 111 toward the radially outward 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 rotational axis direction toward the radially outer side of the connecting wall portion 113 .

The cam contact portion 115 comes into contact with a first cam surface 126 (described below) of the rotating cam 120. The cam contact portion 115 extends from a portion of the radially outer end 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-symmetrical about 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 forms an inclined surface 115A that is approximately parallel to the first cam surface 126.

The rotation restriction portion 116 has a rib shape that protrudes radially outward from the outer peripheral surface of the cam contact portion 115 and extends in the direction of the rotation axis. Two rotation restriction portions 116 are provided, one for each cam contact portion 115. The rotation restriction portion 116 is provided so as to protrude from the end of the arc-shaped cam contact portion 115 opposite the inclined surface 115A in the circumferential direction.

The rotating cam 120 rotates in conjunction with the linear motion of the linear 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.

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

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 disc portion 121 toward one side in the direction of the rotation axis. Two first cam portions 122 are provided. The two first cam portions 122 have shapes that are point-symmetrical with respect to the rotation center of the rotating cam 120.

The rotating 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 of the first cam portion 122 in the rotational axis direction, and holds the corresponding cam follower 110 in the pressing position. The first holding surface 125 is substantially perpendicular to the rotational axis direction.

The second holding surface 127 is part of the end face on one side of 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.

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

The first cam surface 126 is capable of contacting 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 contacting 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 Figure 5(b)) as it moves from the second holding surface 127 toward the first holding surface 125.

The cam arm 123 extends from the end of one of the first cam portions 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 to extend from the tip of the cam arm 123 toward one side in the rotation axis direction. The cam boss 124 has a cylindrical shape.

As shown in FIGS. 6A and 6B, 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. 6A, 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. 6B, 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.

The cam support portion 330 is a portion that rotatably supports the rotating cam 120. As shown in Figure 3, the cam support portion 330 has a generally cylindrical shape, and four are provided, one for each rotating cam 120. The cam support portion 330 is 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 Figure 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.

The cam support portion 330 has a pair of rotation restriction grooves 331 extending in the direction of the rotation axis. The rotation restriction portion 116 of the cam follower 110 engages with the corresponding rotation restriction groove 331 of the cam support portion 330, thereby restricting rotation around the first shaft 119.

The image forming apparatus 1 is equipped with compression coil springs 150 as an example of a first spring. Four compression coil springs 150 are provided, one for each cam follower 110. The compression coil springs 150 urge the corresponding cam follower 110 toward the non-pressed position. For example, the compression coil spring 150 provided corresponding to the first cam follower 110K urges the first cam follower 110K toward the non-pressed position.

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

As shown in FIG. 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 to correspond to one of the development cartridges 60.

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).

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

As shown in Figures 7(a) and (b), clutch 160 (160K, 160Y, 160M, 160C) has a planetary gear mechanism equipped with a sun gear 161, a ring gear 162, a carrier 163, and two planetary gears 164. Clutch 160 has an input element 160A, an output element 160B, and a transfer element 160D. Input element 160A, output element 160B, and transfer element 160D are rotatable coaxially.

Clutch 160 has an input element 160A, an output element 160B, and a transfer element 160D; one of these elements has a sun gear 161, the other has a ring gear 162, and the remaining has a carrier 163. In this embodiment, transfer element 160D has the sun gear 161, input element 160A has the ring gear 162, and output element 160B has the carrier 163.

The input element 160A is an element to which a driving force is input, and includes 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.

The transfer element 160D is an element configured to be able to transfer driving force from the input element 160A to the output element 160B when rotation is restricted, and not to transfer driving force from the input element 160A to the output element 160B when rotation is not restricted. The transfer element 160D has a sun gear 161, a rotating plate 167 that rotates integrally with the sun gear 161, and a plurality of claws 168 provided on the outer periphery of the 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.

When the rotation of the transfer element 160D is stopped, the clutch 160 is in a transmission state where the driving force input to the first outer peripheral gear 165 can be transmitted 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 transmitted 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.

The switching lever 140 is movable between a transmission position shown in FIG. 8(b), in which 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), in which 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.

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.

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.

As shown in Figure 8(b), when the switching lever 140 is in the transmission position, it engages with the claw portion 168 of the transfer element 160D, putting the clutch 160 in a 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 a planetary gear mechanism." Also, as shown in Figure 8(a), when the switching lever 140 is in the disengagement position, it disengages from the claw portion 168 of the transfer element 160D, putting the clutch 160 in a disengaged state. The switching lever 140 can swing between the transmission position and the disengagement position around the swing axis 140A, which is the central axis of the second shaft 340.

The second shaft 340 is a shaft that supports the switching lever 140 so that it 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.

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.

The first lever 141 is capable of swinging around the 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.

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 radially outer side of the first support portion 141A.
The lever boss 141C protrudes from the tip of the first arm 141B toward one side in the rotation axis direction. The lever boss 141C has a cylindrical shape.

The first protrusion 141E and the second protrusion 141F protrude from the outer peripheral surface of the first support portion 141A toward the radially outer side 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 rotation axis direction.

The second lever 142 is pivotable around the pivot shaft 140A and is capable of engaging 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.

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 radially outer side of the second support portion 142A.

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.

The lever protrusion 142D protrudes from the second support portion 142A toward the other side in the rotation axis direction. As shown in Figure 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 rotation axis direction.

The torsion spring 143 biases the second lever 142 toward the first lever 141 in a direction that causes the lever protrusion 142D of the second lever 142 to contact the first protrusion 141E provided on the first lever 141. The torsion spring 143 has a coil 143A, a first spring arm 143B extending from one end of the coil 143A toward the outside in the radial direction of the coil 143A, and a second spring arm 143C extending from the other end of the coil 143A toward the outside in the radial direction of the coil 143A.

The torsion spring 143 is positioned 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), bringing the lever protrusion 142D into contact with the first protrusion 141E. The first protrusion 141E restricts the swing of the second lever 142 in the direction in which the tip 142C of the second lever 142 approaches the transfer element 160D.

As shown in FIG. 9(c), the second lever 142 can swing counterclockwise relative to the first lever 141 against the biasing force of the torsion spring 143. The first lever 141 is provided with a second protrusion 141F. When the second lever 142 swings a predetermined amount counterclockwise relative to the first lever 141 against the biasing force of the torsion spring 143, the 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.

Returning to FIG. 9(b), the image forming apparatus 1 is equipped with tension coil springs 144 as an example of a third spring. Four tension coil springs 144 are provided, one for each switching lever 140 (see FIG. 2). The tension coil springs 144 bias the corresponding switching lever 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.

More specifically, one end of the tension coil spring 144 is hooked onto the spring hook 141H provided on the first lever 141, and the other end, in a slightly stretched state, is hooked onto 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 figure, 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.

As shown in FIG. 10, the linear motion plate 200 is supported by the frame 300 (housing 10) so that it can move linearly. Specifically, the linear motion plate 200 can move linearly 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 can move linearly in the front-to-rear direction, which is the direction in which the photosensitive drums 50 are lined up, between the first and second positions. The second position is a position forward of the first position.

The linear motion plate 200 can move linearly between the first position and the second position via the 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.

Returning to Figure 10, the frame 300 has multiple guides 351-359. Each guide 351-359 protrudes from the main body 310 in the direction of the rotation axis and extends forward and backward. Guides 351-355 are provided above the linear motion plate 200, and guides 356-359 are provided below the linear motion plate 200. Guides 351-355 and guides 356-359 hold the linear motion plate 200 so that it is sandwiched between them from above and below, and support the linear motion plate 200 so that it can move linearly forward and backward.

The linear motion plate 200 is configured to move the first cam follower 110K between the pressed position and the non-pressed position and to move the first switching lever 140K between the disengaged position and the transmitted position by linear motion in the forward and backward directions. The linear motion plate 200 is also configured to move the second cam follower 110Y, the third cam follower 110M, and the fourth cam follower 110C between the pressed position and the non-pressed position and to move the second switching lever 140Y, the third switching lever 140M, and the fourth switching lever 140C between the disengaged position and the transmitted position by linear motion in the forward and backward directions.

As shown in FIG. 11, when the linear 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 disengaging 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 disengaging 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.

As shown in FIG. 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 device 1 is in a state where the first black developer cartridge 60K is in the contact position, allowing the driving force from the first motor M1 to be transmitted to the first developing roller 61K, and the yellow, magenta, and cyan developer cartridges 60Y, 60M, and 60C are in the separated positions, preventing the driving force from the first motor M1 from being transmitted to the developing rollers 61Y, 61M, and 61C.

As shown in FIG. 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 transmission 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 transmission 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.

The pivoting 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 pivoting cam 120 is positioned in the second cam position, the cam contact portion 115 of the cam follower 110 contacts the second holding surface 127 of the pivoting cam 120 and is supported by the second holding surface 127. Also, as shown in FIG. 11, when the pivoting cam 120 is positioned in the first cam position, the cam contact portion 115 of the cam follower 110 contacts the first holding surface 125 of the pivoting cam 120 and is supported by the first holding surface 125.

As shown in FIG. 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 on the housing 10.

The first cam groove 210 moves the first cam follower 110K between the pressing position and the non-pressing position due to the linear movement of the linear plate 200. The 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 plate 200 moves linearly, 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.

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 actuator plate 200. The lever boss 141C of the first switching lever 140K engages with the first lever groove 220. The first lever groove 220 has a vertical groove 222 extending vertically, 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 actuator 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.

The linear actuator plate 200 is configured 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 positioned downstream of the vertical groove 211 of the first cam groove 210 in the direction in which the linear actuator plate 200 moves from the first position to the second position. More specifically, the vertical groove 222 of the first lever groove 220 is positioned ahead of the vertical groove 211 of the first cam groove 210.

The second cam grooves 230 move the cam followers 110Y, 110M, and 110C between the pressed position and the non-pressed position due to the linear motion of the linear motion plate 200. Three second cam grooves 230 are provided, one for each cam follower 110Y, 110M, and 110C. The cam bosses 124 of the corresponding rotating cams 120Y, 120M, and 120C engage with the second cam grooves 230.

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 pivoting cam 120Y, 120M, 120C in the first cam position. The vertical groove 232 acts on the cam boss 124 of the corresponding pivoting cam 120Y, 120M, 120C as the linear motion of the linear motion plate 200 occurs, causing the pivoting cam 120Y, 120M, 120C to pivot between the first cam position and the second cam position.

The second lever grooves 240 move the switching levers 140Y, 140M, and 140C between the disconnection position and the transmission position through the linear motion of the linear motion plate 200. Three second lever grooves 240 are provided, one for each of the switching levers 140Y, 140M, and 140C. The lever bosses 141C of the corresponding switching levers 140Y, 140M, and 140C engage with the second lever grooves 240.

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 disengagement 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 disengagement position and the transmission position. The horizontal groove 243 maintains the corresponding switching lever 140Y, 140M, 140C in the transmission position.

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.

Specifically, the vertical groove 242 of the second lever groove 240 is positioned 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 positioned ahead of the vertical groove 232 of the second cam groove 230.

The rack gear 250 is formed on the underside of the rear end of the linear motion plate 200. The rack gear 250 meshes with the 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 reverse. 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 reverse and the drive gear 260 rotates counterclockwise in FIG. 10, the linear motion plate 200 moves linearly from front to rear.

The control unit 2 is equipped with 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 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.

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.

When the drive gear 260 rotates clockwise in Figure 11, the linear motion plate 200 moves linearly forward from the first position to the second position. As a result, the cam boss 124 of the first rotating cam 120K is pushed forward by the wall of the vertical groove 211, causing the first rotating cam 120K to begin rotating counterclockwise in Figure 11 from the first cam position.

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. The lever boss 141C is then 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 causing the first developing roller 61K to begin to drive.

When 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 slides the first cam follower 110K from the pressed position to the non-pressed position.

As shown in Figure 13, when the linear plate 200 is positioned in 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 retaining surface 127, and the first cam follower 110K is positioned in the non-pressing position. As a result, the first developing cartridge 60K is positioned in the contact position, and the first developing roller 61K contacts the first photosensitive drum 50K.

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

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

When the linear motion plate 200 moves further forward from the third position toward the second position, the cam bosses 124 of the pivoting cams 120Y, 120M, and 120C move relative to the lower end of the vertical groove 232 of the second cam groove 230. Then, as the cam bosses 124 are pushed forward by the wall of the vertical groove 232, the pivoting cams 120Y, 120M, and 120C begin to rotate counterclockwise in Figure 13 from the first cam position.

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. The lever boss 141C is then 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. This causes the tip 142C to engage with the claw portion 168 of the transmission element 160D of the corresponding clutch 160Y, 160M, and 160C, transmitting the driving force from the first motor M1 to the developer cartridges 60Y, 60M, and 60C, and the developing rollers 61Y, 61M, and 61C begin to drive.

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

As shown in FIG. 15, when the linear plate 200 is positioned in the second position, the rotating cams 120Y, 120M, and 120C rotate to the second cam position, and the surface that contacts the cam contact portion 115 of the corresponding cam follower 110Y, 110M, or 110C switches from the first cam surface 126 to the second holding surface 127, and the cam follower 110Y, 110M, or 110C is positioned in the non-pressing position. As a result, the developer cartridges 60Y, 60M, and 60C are positioned in the contact position, and the developer rollers 61Y, 61M, and 61C contact the corresponding photosensitive drums 50Y, 50M, and 50C.

When the linear plate 200 is in the second position, printing can be performed using all of the developing rollers 61.

When the drive gear 260 rotates counterclockwise in Figure 15, the linear motion plate 200 moves linearly backward from the second position to the first position. As a result, the cam bosses 124 of the rotating cams 120Y, 120M, and 120C are pushed backward by the wall of the vertical groove 232 of the second cam groove 230, causing the rotating cams 120Y, 120M, and 120C to begin rotating clockwise in Figure 15 from the second cam position. The lever boss 141C moves relatively along the horizontal groove 243 of the second lever groove 240, preventing the switching levers 140Y, 140M, and 140C from swinging and maintaining them in the transmission position.

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, pressing against the corresponding developer cartridges 60Y, 60M, and 60C. This causes the developer rollers 61Y, 61M, and 61C to separate from the corresponding photosensitive drums 50Y, 50M, and 50C.

When the developing rollers 61Y, 61M, and 61C separate from their corresponding photosensitive drums 50Y, 50M, and 50C, as shown in FIG. 14, the lever boss 141C of the switching levers 140Y, 140M, and 140C moves relative to the upper end of the vertical groove 242 of the second lever groove 240. The lever boss 141C is then pushed backward by the wall of the vertical groove 242, causing the switching levers 140Y, 140M, and 140C to swing from the transmission position to the disengagement position against the biasing force of the tension coil spring 144. This causes the tip 142C to disengage from the transmission element 160D of the corresponding clutch 160Y, 160M, and 160C, preventing the driving force from the first motor M1 from being transmitted to the developing cartridges 60Y, 60M, and 60C, causing the developing rollers 61Y, 61M, and 61C to stop.

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, and 110C come into contact with the first holding surfaces 125 of the corresponding pivot cams 120Y, 120M, and 120C.
While the linear motion plate 200 moves from the second position to the third position, the first pivoting 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.

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 pivoting cam 120K moves relative to the upper end of the vertical groove 211 of the first cam groove 210. Then, as the cam boss 124 is pushed backward by the wall of the vertical groove 211, the first pivoting cam 120K begins to rotate clockwise in Figure 13 from the first cam position. The first switching lever 140K does not swing because the lever boss 141C moves relatively along the horizontal groove 223 of the first lever groove 220, and is maintained in the transmission position.

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, pressing the first developing cartridge 60K. This causes the first developing roller 61K to separate from the first photosensitive drum 50K.

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, as the lever boss 141C is pushed rearward by the wall of the vertical groove 222, the first switching lever 140K pivots from the transmission position to the disengagement position against the biasing force of the tension coil spring 144. This causes the tip 142C to disengage from the transmission element 160D of the clutch 160K, preventing the driving force from the first motor M1 from being transmitted to the first developing cartridge 60K, and the first developing roller 61K stops. 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 contacts the first holding surface 125 of the first rotating cam 120K.

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 that slides a 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 electromagnetic clutch to transmit 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, allowing for a space-saving configuration, and there is no need to provide a gear train or electromagnetic clutch to transmit the drive force from the motor to the rotating cam 120. As a result, 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.

In addition, a compression coil spring 150 is provided to bias the cam follower 110 toward the non-pressing position, so that the cam follower 110 can be reliably positioned in the non-pressing position when the linear plate 200 is positioned in the second position.

In addition, because the corresponding switching lever 140 is moved to the transmission position before the cam follower 110 moves to the non-pressing position, the developing roller 61 can be rotated before coming into contact with the corresponding photosensitive drum 50. In addition, because the corresponding switching lever 140 is moved to the disconnection position after the cam follower 110 moves to the pressing position, the developing roller 61 can be stopped after it has separated from the corresponding photosensitive drum 50.

In addition, because 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 transfer element 160D, excessive force is not applied to the switching lever 140.

In addition, the first lever 141 is provided with a first protrusion 141E and a second protrusion 141F, which can determine the swing range of the second lever 142.

In addition, a tension coil spring 144 is provided to bias the switching lever 140 toward the transmission position, so that the switching lever 140 can be reliably positioned in the transmission position when the linear motion plate 200 is in the second position.

Furthermore, when the linear motion plate 200 is in the first position, all of the developing rollers 61 are separated from their corresponding photosensitive drums 50; when the linear motion plate 200 is in 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 in the second position, all of the developing rollers 61 are in contact with their 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 their 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.

Next, a second embodiment will be described. Note that the following description will focus on differences from the first embodiment, and descriptions 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 rotary cam.

The cam followers 110 (first cam follower 110K, second cam follower 110Y, third cam follower 110M, and fourth cam follower 110C) have a pin 111 and a first flange portion 112 extending radially outward from the outer circumferential surface of the pin 111.

The linear 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 direction of the rotation axis. 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 direction of the rotation axis and is connected to the upper end of the fourth plate portion 204. The fourth plate portion 204 is located at a different position in the direction of the rotation axis from the second plate portion 202. Specifically, the fourth plate portion 204 is located closer to the frame 300 in the direction of the rotation axis than the second plate portion 202. The fourth plate portion 204 has a first lever groove 220, three second lever grooves 240, and a rack gear 250.

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.

The holding surface 272 is an end surface on one side of the second cam portion 270 in the rotational axis direction, 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 Figure 17) from the rear to the front.

Three third cam portions 280 are provided corresponding to the second cam follower 110Y, the third cam follower 110M, and the fourth cam follower 110C, and have 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. In the movement direction (front-to-back direction) of the linear motion plate 200, the length of the third cam portion 280 is longer than the length of the second cam portion 270. The third cam portion 280 has a third cam surface 281 and a retaining surface 282.

The holding surface 282 is the end face on one side of the third cam portion 280 in the rotational axis direction, 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-to-back direction) of the linear motion plate 200, the length of the holding surface 282 is longer than the length of the holding surface 272.

The third cam surface 281 slides the corresponding cam follower 110Y, 110M, 110C between the pressing position and the non-pressing position due to the linear motion of the linear motion plate 200. The third cam surface 281 is capable of contacting the corresponding cam follower 110Y, 110M, 110C and is inclined relative to the movement direction of the linear motion plate 200. Specifically, the third cam surface 281 is inclined so that it approaches the corresponding developer cartridge 60Y, 60M, 60C (the front side in Figure 17) from rear to front.

As shown in Figure 18(a), when the cam follower 110 is in the pressed position, the first flange portion 112 contacts the retaining surfaces 272, 282 of the corresponding cam portions 270, 280. Also, as shown in Figure 18(b), when the cam follower 110 is in the non-pressed position, the first flange portion 112 does not contact the corresponding cam portion 270, 280. When the cam follower 110 is in the non-pressed position, the first flange portion 112 contacts the end face of the second plate portion 202 on one side in the rotational axis direction. The cam follower 110 is biased toward the non-pressed position by the compression coil spring 150.

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 and 282 of the cam portions 270 and 280 are indicated by dot hatching.
As shown in FIG. 19, when the linear motion plate 200 is in the first position, all the cam followers 110 are in the pressing position, and all the switching levers 140 are in the disconnecting position.

When the linear motion plate 200 moves linearly forward from the first position shown in FIG. 19 to the third position shown in FIG. 20, the first lever groove 220 causes the first switching lever 140K to swing from the disengagement position to the transmission position, and the tip 142C engages with the claw portion 168 (transmission element 160D) of the clutch 160K. This causes the driving force from the first motor M1 to be transmitted to the first developing cartridge 60K, and the first developing roller 61K begins to drive.

The surface of the first cam follower 110K that contacts 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 second cam surface 271 causes the first cam follower 110K to slide from the pressing position to the non-pressing position. Then, when the first flange portion 112 no longer contacts the second cam surface 271 (second cam portion 270) and contacts the second plate portion 202, the first cam follower 110K is positioned in the non-pressing position. This positions the first developer cartridge 60K in the contact position, and the first developer roller 61K contacts the first photosensitive drum 50K.

While the linear plate 200 moves from the first position to the third position, the switching levers 140Y, 140M, and 140C are maintained in the disconnection position. Furthermore, the cam followers 110Y, 110M, and 110C do not slide and are maintained in the pressing position because the first flange portion 112 remains in contact with the holding surface 282 of the third cam portion 280.

When the linear motion plate 200 moves further forward from the third position shown in FIG. 20 toward the second position shown in FIG. 21, the second lever groove 240 causes the switching levers 140Y, 140M, 140C to swing from the disengagement position to the transmission position, and the tip 142C engages with the claw portion 168 (transmission element 160D) of the corresponding clutch 160Y, 160M, 160C. This causes the driving force from the first motor M1 to be transmitted to the developer cartridges 60Y, 60M, 60C, and the developer rollers 61Y, 61M, 61C begin to drive.

The surface of the cam follower 110Y, 110M, 110C that contacts 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 third cam surface 281 causes the cam follower 110Y, 110M, 110C to slide from the pressing position to the non-pressing position. Then, when the first flange portion 112 no longer contacts the third cam surface 281 (third cam portion 280) and contacts the second plate portion 202, the cam follower 110Y, 110M, 110C is positioned in the non-pressing position. This positions the developer cartridge 60Y, 60M, 60C in the contact position, and the developer roller 61Y, 61M, 61C contacts the corresponding photosensitive drum 50Y, 50M, 50C.

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

When the linear motion plate 200 moves linearly backward from the second position shown in FIG. 21 toward the third position shown in FIG. 20, the second lever groove 240 causes the switching levers 140Y, 140M, 140C to swing from the transmission position to the disconnection position, and the tip 142C disengages from the transmission element 160D of the corresponding clutch 160Y, 160M, 160C. As a result, the driving force from the first motor M1 is no longer transmitted to the developer cartridges 60Y, 60M, 60C, and the developer rollers 61Y, 61M, 61C stop.

The first flange portion 112 of the cam follower 110Y, 110M, 110C contacts the third cam surface 281 of the corresponding third cam portion 280, and the third cam surface 281 causes the cam follower 110Y, 110M, 110C to slide from the non-pressing position to the pressing position. The cam follower 110Y, 110M, 110C then moves to the pressing position when the surface with which the first flange portion 112 contacts switches from the third cam surface 281 to the holding surface 282. This positions the developer cartridge 60Y, 60M, 60C in the separated position, and the developer roller 61Y, 61M, 61C separates from the corresponding photosensitive drum 50Y, 50M, 50C.

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. Furthermore, 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 therefore maintained in the non-pressing position.

When the linear motion plate 200 moves further backward from the third position shown in FIG. 20 toward the first position shown in FIG. 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.

The first cam follower 110K slides from the non-pressing position to the pressing position due to the second cam surface 271 contacting the first flange portion 112 of the second cam portion 270. The first cam follower 110K then moves to 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 in the separated position, and the first developing roller 61K separates from the first photosensitive drum 50K.

According to the second embodiment described above, as with the first embodiment, 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 more compact. In particular, the second embodiment does not include a rotating cam, and the cam follower 110 is slid directly by the linear motion plate 200, making it 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.

The above describes an embodiment, but the image forming device can be modified as appropriate, as exemplified below.

In the above embodiment, a compression coil spring 150 was used as an example of 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 and third springs. Furthermore, the image forming apparatus may be configured without a third spring, for example.

In the above embodiment, the first lever 141 of the switching lever 140 was provided with a second protrusion 141F for defining the swing range of the second lever 142. However, for example, the first lever may not be provided with a second protrusion. Also, in the above embodiment, the switching lever 140 had the first lever 141 and the second lever 142, and the second lever 142 was swingable relative to the first lever 141. However, for example, the switching lever may be a component in which the first lever 141 and the second lever 142 of the above embodiment are integrally molded.

In the above embodiment, the linear motion plate 200 was configured to be linearly movable between the first position and the second position via the third position. However, 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 in the first position, all cam followers may be in the pressing position and all switching levers may be in the disengaging position, and when the linear motion plate is in the second position, all cam followers may be in the non-pressing position and all switching levers may be in the transmitting position.

The linear motion plate may also 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. The linear motion plate may also be configured to be able to move linearly between the first position and the second position via a third position, a 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 moving plate is in the first position, four cam followers are in the pressing position and four switching levers are in the disconnecting position; when the linear moving plate is in the third position, one cam follower is in the non-pressing position and one corresponding switching lever is in the transmitting position; when the linear moving plate is in the fourth position, two cam followers are in the non-pressing position and two corresponding switching levers are in the transmitting position; when the linear moving plate is in the fifth position, three cam followers are in the non-pressing position and three corresponding switching levers are in the transmitting position; and when the linear moving plate is in the second position, four cam followers are in the non-pressing position and four switching levers are in the transmitting position.

In the above embodiment, the image forming device 1 was a color printer equipped with multiple photosensitive drums 50 and corresponding multiple developing cartridges 60, cam followers 110, and switching levers 140. However, for example, the image forming device may be a monochrome printer equipped with only one photosensitive drum and one developing cartridge, one cam follower, and one switching lever. Furthermore, for example, the image forming device may be a copier, multifunction device, etc.

The elements described in the above embodiments and variations may be implemented in any combination.

1 Image forming apparatus 50K First photosensitive drum 60K First developing cartridge 61K First developing roller 110K First cam follower 140K First switching lever 200 Linear motion plate M1 First motor

Claims (12)

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; 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. The image forming apparatus described in claim 1, characterized in that the linear motion plate has a second cam surface that is capable of contacting the first cam follower and is inclined with respect to the movement direction of the linear motion plate, and that causes the first cam follower to slide between the pressing position and the non-pressing position due to the linear motion of the linear motion plate. An image forming apparatus as described in claim 2 or claim 3, characterized in that it comprises a first spring that biases the first cam follower toward the non-pressing position. An image forming apparatus according to any one of claims 1 to 4, characterized in that the linear motion 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. 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. 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. The image forming apparatus described in 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. The image forming apparatus of any one of claims 1 to 8, further comprising a third spring that biases the first switching lever toward the transmission position. 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. An image forming apparatus as described in claim 10, characterized in that 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. An image forming apparatus according to any one of claims 1 to 11, characterized in that the first cam follower has a pin extending in the direction of the rotation axis and pressing against the first developing cartridge.