JP2019179121A - Image forming apparatus - Google Patents

Abstract

To provide an image forming apparatus that can stop rotation of a developing roller while locating the developing roller at a separation position.SOLUTION: An image forming apparatus comprises: a motor 11; a joint 21Y; a first gear 22Y; a second gear 23Y; a spring 24Y; a support member 26Y; a rod 27Y; a shaft 29Y; a cam 30Y; a third gear 31Y; and an electromagnetic clutch 32Y. A power from the motor 11 is transmitted to the second gear 23Y and third gear 31Y. When the electromagnetic clutch 32Y is turned on, the cam 30Y rotates from a pressing position to a pressing release position. When the cam 30Y is located at the pressing release position, the support member 26Y is located at a second support position. A developing roller is then located at a separation position by the rod 27Y and lever 28Y. When transmission of power from the second gear 23Y to the first gear 22Y is cancelled, rotation of the developing roller is stopped.SELECTED DRAWING: Figure 5

Description

  The present invention relates to an image forming apparatus.

  Conventionally, an image forming apparatus includes a photosensitive drum, a developing roller, a cam, and a motor. The developing roller is movable between a contact position where the developing roller is in contact with the photosensitive drum and a separated position where the developing roller is separated from the photosensitive drum. The cam moves the developing roller between the contact position and the separation position. The motor rotates the cam (see Patent Document 1 below).

JP 2012-128017 A

  However, in the image forming apparatus described in Patent Document 1, the developing roller can be moved between the contact position and the separation position by the cam and the motor, but when the development roller is located at the separation position. In addition, the rotation of the developing roller cannot be stopped.

  From the viewpoint of suppressing the deterioration of the developing roller, it is desirable to stop the developing roller located at the separated position.

  Accordingly, an object of the present disclosure is to provide an image forming apparatus capable of stopping the rotation of the developing roller in a state where the developing roller is positioned at the separation position.

  The image forming apparatus of the present invention includes a photosensitive drum, a developing roller, a motor, a joint, a first gear, a second gear, a spring, a support member, a rod, a shaft, a cam, and a third. A gear and an electromagnetic clutch are provided.

  The developing roller is movable between a contact position where the developing roller is in contact with the photosensitive drum and a separated position where the developing roller is separated from the photosensitive drum.

  The joint transmits power to the developing roller. The joint has a joint gear. The joint is rotatable about the first axis. The first axis extends in the axial direction.

  The first gear meshes with the joint gear. The first gear is rotatable about the second axis. The second axis extends in the axial direction.

  The second gear receives power from the motor. The second gear can move in the axial direction between a transmission position where the second gear can rotate with respect to the second axis together with a release position where the second gear can rotate with respect to the second axis when the first gear is stopped. is there.

  The spring is located between the first gear and the second gear in the axial direction. The spring presses the second gear located at the transmission position toward the release position.

  The support member supports the second gear. The support member is movable in the axial direction together with the second gear. The support member is movable between a first support position where the second gear is located at the transmission position and a second support position where the second gear is located at the release position.

  The rod moves the developing roller between the contact position and the separation position. The rod is movable in the axial direction together with the support member. The rod is positioned at the advancing position where the developing roller is positioned at the contact position when the supporting member is positioned at the first supporting position, and the developing roller is positioned at the separated position when the supporting member is positioned at the second supporting position. Located in the retracted position. The rod extends along the second axis. The rod passes through the first gear and the second gear.

  The shaft is rotatable about the third axis. The third axis extends in the axial direction. The shaft extends along the third axis.

  The cam is rotatable about the third axis together with the shaft. The cam presses the support member to place the support member in the first support position, and releases the pressure on the support member to allow the support member to be positioned in the second support position. It is possible to rotate between them.

  The third gear can rotate about the third shaft by receiving power from the motor.

  The electromagnetic clutch includes an armature and a rotor. The armature is attached to the third gear. The rotor is attached to the shaft. The electromagnetic clutch can be switched between an on state in which the shaft can rotate together with the third gear and an off state in which the third gear can rotate with the shaft stopped. The electromagnetic clutch is turned on for a predetermined time in a state where the cam is located at the pressure release position, and then turned off, thereby rotating the cam from the pressure release position to the pressure position. The electromagnetic clutch is turned on for a predetermined time with the cam positioned at the pressing position, and then turned off, thereby rotating the cam from the pressing position to the pressing release position.

  According to such a configuration, when the cam is positioned at the pressing position and the support member is positioned at the first support position, the rod is positioned at the advance position where the developing roller is positioned at the contact position. Thereby, the developing roller can be positioned at the contact position.

  Further, when the support member is located at the first support position, the second gear is located at the transmission position. When the second gear is located at the transmission position, the second gear rotates together with the first gear. Thereby, the motive power from a motor can be transmitted to a joint via a 2nd gear and a 1st gear.

  As a result, the developing roller can be rotated with the developing roller positioned at the contact position.

  On the other hand, when the cam is positioned at the pressing release position and the support member is positioned at the second support position, the rod is positioned at the retracted position where the developing roller is positioned at the separation position. Thereby, the developing roller can be positioned at the separation position.

  Further, when the support member is located at the second support position, the second gear is located at the release position. When the second gear is located at the release position, the second gear rotates with the first gear stopped. Thereby, the transmission of power from the second gear to the first gear can be canceled, and the transmission of power from the motor to the joint can be canceled.

  As a result, the rotation of the developing roller can be stopped with the developing roller positioned at the separation position.

  According to the image forming apparatus of the present invention, the rotation of the developing roller can be stopped in a state where the developing roller is located at the separation position.

FIG. 1 is a schematic configuration diagram of the image forming apparatus, and shows a state where each of the four developing rollers is located at a contact position. FIG. 2 shows the image forming apparatus shown in FIG. 1 and shows a state where each of the four developing rollers is located at a separation position. FIG. 3 is a plan view of the switching mechanism and shows a case where the switching mechanism is in a power transmission state. FIG. 4 is a perspective view of the switching mechanism shown in FIG. FIG. 5 shows a case where the switching mechanism shown in FIG. 3 is in a transmission release state. FIG. 6 is a perspective view of the switching mechanism shown in FIG.

1. Outline of Image Forming Apparatus 1 An outline of the image forming apparatus 1 will be described with reference to FIG.

  The image forming apparatus includes a main body casing 2, a paper feed tray 3, four photosensitive drums 4Y, 4M, 4C, and 4K, four chargers 5Y, 5M, 5C, and 5K, an exposure device 6, and four developing units. Cartridges 7Y, 7M, 7C, and 7K, a transfer device 8, and a fixing device 9 are provided.

1.1 Main Body Casing The main body casing 2 constitutes the exterior of the image forming apparatus 1. The main body casing 2 includes a paper feed tray 3, four photosensitive drums 4Y, 4M, 4C, and 4K, four chargers 5Y, 5M, 5C, and 5K, an exposure device 6, and four developing cartridges 7Y, 7M, 7C and 7K, the transfer device 8, and the fixing device 9 are accommodated.

1.2 Paper Feed Tray The paper feed tray 3 stores sheets S. The sheet S in the paper feed tray 3 is conveyed toward the photosensitive drum 4Y. The sheet S is, for example, printing paper. The photosensitive drum 4Y will be described later.

1.3 Four photosensitive drums The four photosensitive drums 4Y, 4M, 4C, and 4K are arranged in the first direction. The photosensitive drum 4Y is rotatable about a drum shaft extending in the second direction. The second direction is a direction that intersects the first direction. Preferably, the second direction is orthogonal to the first direction. The photosensitive drum 4Y extends in the second direction and has a cylindrical shape. The structures of the photosensitive drums 4M, 4C, and 4K are the same as the structure of the photosensitive drum 4Y. Therefore, description of the structure of each of the photosensitive drums 4M, 4C, and 4K is omitted.

1.4 Four Chargers The charger 5Y charges the peripheral surface of the photosensitive drum 4Y. The charger 5M charges the peripheral surface of the photosensitive drum 4M. The charger 5C charges the peripheral surface of the photosensitive drum 4C. The charger 5K charges the peripheral surface of the photosensitive drum 4K. Each of the four chargers 5Y, 5M, 5C, and 5K is specifically a scorotron charger. Each of the four chargers 5Y, 5M, 5C, and 5K may be a charging roller.

1.5 Exposure Device The exposure device 6 exposes the photosensitive drum 4Y. After the charger 5Y charges the peripheral surface of the photosensitive drum 4Y, the exposure device 6 irradiates the charged peripheral surface of the photosensitive drum 4Y with light to expose the static surface of the photosensitive drum 4Y. An electrostatic latent image is formed. Specifically, the exposure device 6 is a laser scan unit that scans the circumferential surface of the photosensitive drum 4Y with laser light. The exposure device 6 may be an LED unit including an LED array. The exposure device 6 also exposes the photosensitive drums 4M, 4C, and 4K.

1.6 Four Development Cartridges The development cartridge 7Y can accommodate toner. The developing cartridge 7Y can be attached to the image forming apparatus 1. The developing cartridge 7Y includes a developing roller 10Y. That is, the image forming apparatus 1 includes a developing roller 10Y.

  The developing roller 10Y is rotatable about a developing roller shaft extending in the second direction. The developing roller 10Y extends in the second direction and has a cylindrical shape. A part of the developing roller 10Y is accommodated in the developing cartridge 7Y. The developing roller 10Y contacts the peripheral surface of the photosensitive drum 4Y in a state where the developing cartridge 7Y is mounted on the image forming apparatus 1. Thus, the developing roller 10Y can supply the toner in the developing cartridge 7Y to the peripheral surface of the photosensitive drum 4Y. The developing roller 10Y supplies the toner in the developing cartridge 7Y to the peripheral surface of the photosensitive drum 4Y, whereby the electrostatic latent image is developed, and a toner image is formed on the peripheral surface of the photosensitive drum 4Y.

  The developing cartridge 7M includes a developing roller 10M. The developing cartridge 7C includes a developing roller 10C. The developing cartridge 7K includes a developing roller 10K. That is, the image forming apparatus 1 includes four developing rollers 10Y, 10M, 10C, and 10K. The developing roller 10M can supply the toner in the developing cartridge 7M to the peripheral surface of the photosensitive drum 4M. The developing roller 10C can supply the toner in the developing cartridge 7C to the peripheral surface of the photosensitive drum 4C. The developing roller 10K can supply the toner in the developing cartridge 7K to the peripheral surface of the photosensitive drum 4K.

1.7 Transfer Device The transfer device 8 transfers the toner images formed on the four photosensitive drums 4Y, 4M, 4C, and 4K to the sheet S. The sheet S supplied from the sheet feeding tray 3 is conveyed toward the fixing unit 9 through between the transfer device 8 and the four photosensitive drums 4Y, 4M, 4C, and 4K. At this time, the transfer device 8 transfers the toner image formed on each of the four photosensitive drums 4Y, 4M, 4C, and 4K to the sheet S.

1.8 Fixing Device The fixing device 9 heats and pressurizes the sheet S on which the toner image is transferred, and fixes the toner image on the sheet S. The sheet S that has passed through the fixing device 9 is discharged onto the upper surface of the main casing 2.

2. Details of Image Forming Apparatus Next, details of the image forming apparatus 1 will be described with reference to FIGS.

  As shown in FIG. 3, the image forming apparatus 1 includes a motor 11, a separation member 12Y, and a switching mechanism 13Y. The image forming apparatus 1 further includes separation members 12M, 12C, and 12K and switching mechanisms 13M, 13C, and 13K. That is, the image forming apparatus 1 includes four switching mechanisms 13Y, 13M, 13C, and 13K. Each of the separation members 12M, 12C, and 12K has the same structure as the separation member 12Y, and the switching mechanisms 13M, 13C, and 13K have the same structure as the switching mechanism 13Y. Therefore, in the following description, illustration and description of the separation members 12M, 12C, and 12K and the switching mechanisms 13M, 13C, and 13K are omitted.

2.1 Motor The motor 11 is provided in the main casing 2. The power of the motor 11 is transmitted to the idle gear 25Y and the third gear 31Y of the switching mechanism 13Y by a gear train (not shown).

2.2 Separation Member The separation member 12Y moves the developing roller 10Y from the contact position (see FIG. 1) to the separation position (see FIG. 2). That is, the developing roller 10Y is movable between the contact position and the separation position. When the developing roller 10Y is in the contact position, the developing roller 10Y comes into contact with the photosensitive drum 4Y. When the developing roller 10Y is in the separated position, the developing roller 10Y is separated from the photosensitive drum 4Y.

  The separation member 12Y is movable between a first position shown in FIG. 3 and a second position shown in FIG. When the separation member 12Y is located at the first position, the developing roller 10Y is located at the contact position (see FIG. 1). When the separation member 12Y is located at the second position, the developing roller 10Y is located at the separation position (see FIG. 2).

  The separation member 12Y is movable in the axial direction. The axial direction is a direction in which the first axis A1 extends. The first axis A1 will be described later. In this embodiment, the axial direction is the same direction as the second direction. In this embodiment, the separation member 12Y extends in the axial direction and has a prismatic shape.

2.3 Switching Mechanism The switching mechanism 13Y can be switched to the power transmission state shown in FIG. 3 or the transmission release state shown in FIG. When the switching mechanism 13Y is in the power transmission state, the switching mechanism 13Y can position the developing roller 10Y at the contact position (see FIG. 1) and transmit power to the developing roller 10Y. When the switching mechanism 13Y is in the transmission canceling state, the switching mechanism 13Y positions the developing roller 10Y at the separation position (see FIG. 2) and cancels transmission of power to the developing roller 10Y.

  Specifically, as shown in FIGS. 3 and 4, the switching mechanism 13Y includes a joint 21Y, a first gear 22Y, a second gear 23Y, a spring 24Y (see FIG. 4), an idle gear 25Y, a support member 26Y, a rod 27Y, A shaft 29Y, a cam 30Y, a third gear 31Y, an electromagnetic clutch 32Y, and a lever 28Y are provided. That is, the image forming apparatus 1 includes a joint 21Y, a first gear 22Y, a second gear 23Y, a spring 24Y, an idle gear 25Y, a support member 26Y, a rod 27Y, a shaft 29Y, a cam 30Y, a third gear 31Y, an electromagnetic clutch 32Y, and A lever 28Y is provided.

2.3.1 Joint The joint 21Y transmits power to the developing roller 10Y. The joint 21Y can rotate about the first axis A1. The first axis A1 extends in the axial direction. Specifically, the joint 21Y includes a joint gear 41Y and a coupling 42Y.

  The joint gear 41Y is rotatable about the first axis A1. Specifically, the joint gear 41Y is a spur gear. The joint gear 41Y may be an inclined gear.

  The coupling 42Y can rotate about the first axis A1 together with the joint gear 41Y. The coupling 42Y extends in the axial direction and has a cylindrical shape. The coupling 42Y is fitted into the developing coupling of the developing cartridge 7Y in a state where the developing cartridge 7Y is mounted on the image forming apparatus 1. The development coupling is not shown. The coupling 42 </ b> Y can rotate about the first axis A <b> 1 together with the development coupling while being fitted in the development coupling. Accordingly, the joint 21Y can transmit power to the developing roller 10Y in a state where the coupling 42Y is fitted in the developing coupling. The coupling 42Y is movable in the axial direction with respect to the joint gear 41Y. The coupling 42Y is movable in the axial direction between a position where the coupling 42Y is fitted into the developing coupling and a position where the coupling 42Y is separated from the developing coupling.

2.3.2 First gear The first gear 22Y meshes with the joint gear 41Y. Note that the first gear 22Y does not mesh with the idle gear 25Y. The first gear 22Y is located away from the idle gear 25Y in the axial direction. The first gear 22Y can rotate about the second axis A2. The second axis A2 extends in the axial direction. The first gear 22Y is a spur gear. The first gear 22Y may be an inclined gear. The first gear 22Y has one surface 221 in the axial direction, the other surface 222 in the axial direction, a through hole 223 (see FIG. 3), and a plurality of protrusions 224. The other surface 222 is located closer to the second gear 23Y than the one surface 221 in the axial direction.

  The rod 27Y is inserted through the through hole 223. Thereby, the first gear 22Y can rotate about the rod 27Y.

  Each of the plurality of protrusions 224 is located on the other surface 222. Each of the plurality of protrusions 224 extends from the other surface 222 toward the second gear 23Y. Each of the plurality of protrusions 224 extends in the axial direction. The plurality of protrusions 224 are spaced apart from each other in the circumferential direction of the first gear 22Y.

2.3.3 Second Gear The second gear 23Y receives power from the motor 11 via the idle gear 25Y. The second gear 23Y can rotate about the second axis A2. Further, the second gear 23Y is movable in the axial direction. The second gear 23Y is movable between the transmission position shown in FIG. 3 and the release position shown in FIG. The second gear 23Y meshes with the idle gear 25Y at both the transmission position and the release position. When the second gear 23Y is located at the transmission position, the second gear 23Y can rotate about the second axis A2 together with the first gear 22Y. Further, when the second gear 23Y is located at the release position, the second gear 23Y can rotate about the second axis A2 with the first gear 22Y stopped. Specifically, as shown in FIG. 3 and FIG. 4, the second gear 23 </ b> Y has one surface 231 in the axial direction, the other surface 232 in the axial direction, a through hole 233 (see FIG. 3), and a plurality of protrusions 234 ( 3). The other surface 232 is located closer to the first gear 22Y than the one surface 231 in the axial direction.

  The rod 27Y is inserted into the through hole 233. Thereby, the 2nd gear 23Y can rotate about rod 27Y.

  Each of the plurality of protrusions 234 is located on the other surface 232. Each of the plurality of protrusions 234 extends from the other surface 232 toward the first gear 22Y. Each of the plurality of protrusions 234 extends in the axial direction. The plurality of protrusions 234 are spaced from each other in the circumferential direction of the second gear 23Y.

  As shown in FIG. 3, when the second gear 23Y is positioned at the transmission position, when the second gear 23Y rotates, one of the plurality of protrusions 234 is one of the plurality of protrusions 224 of the first gear 22Y. One is in contact with the second gear 23Y in the rotating direction. As a result, power is transmitted from the second gear 23Y to the first gear 22Y. Then, the second gear 23Y and the first gear 22Y rotate together in a state where any one of the plurality of protrusions 234 is in contact with any one of the plurality of protrusions 224.

  Further, as shown in FIG. 5, when the second gear 23Y is positioned at the release position, the plurality of protrusions 234 are separated from the plurality of protrusions 224 of the first gear 22Y in the axial direction. Thereby, transmission of power from the second gear 23Y to the first gear 22Y is released. Then, the first gear 22Y stops when the power from the second gear 23Y is not transmitted. On the other hand, the second gear 23Y rotates independently of the first gear 22Y by the power from the motor with the first gear 22Y stopped.

  The second gear 23Y is preferably a spur gear.

2.3.4 Spring The spring 24Y is positioned between the first gear 22Y and the second gear 23Y in the axial direction, as shown in FIG. The spring 24Y is a compression coil spring. The spring 24Y can expand and contract in the axial direction. The spring 24Y is located around the rod 27Y. The spring 24Y is compressed in the axial direction when the second gear 23Y is positioned at the transmission position (see FIG. 3) compared to when the second gear 23Y is positioned at the release position (see FIG. 5). Thereby, the spring 24Y presses the second gear 23Y located at the transmission position toward the release position.

2.3.5 Idle Gear The idle gear 25Y meshes with the second gear 23Y. Power from the motor 11 is transmitted to the idle gear 25Y by a gear train (not shown). The idle gear 25Y is preferably a spur gear.

2.3.6 Support Member The support member 26Y is located on the opposite side of the first gear 22Y with respect to the second gear 23Y in the axial direction. The support member 26Y extends in the axial direction and has a cylindrical shape. The support member 26Y is movable in the axial direction. The support member 26Y is movable between a first support position shown in FIG. 3 and a second support position shown in FIG.

  The support member 26Y moves from the second support position to the first support position, thereby pressing the second gear 23Y from the release position to the transmission position. Thereby, the second gear 23Y moves from the release position to the transmission position against the pressing force of the spring 24Y. At this time, the support member 26Y is movable together with the second gear 23Y. When the support member 26Y is located at the first support position, the second gear 23Y is located at the transmission position. When the support member 26Y is located at the first support position, the support member 26Y supports the second gear 23Y located at the transmission position.

  Further, the support member 26Y moves from the first support position to the second support position, thereby releasing the pressure on the second gear 23Y. As a result, the second gear 23Y moves from the transmission position to the release position by the pressing force of the spring 24Y. Also at this time, the support member 26Y can move together with the second gear 23Y. When the support member 26Y is located at the second support position, the second gear 23Y is located at the release position. When the support member 26Y is located at the second support position, the support member 26Y is separated from the second gear 23Y located at the release position. The support member 26Y may contact the second gear 23Y located at the release position when the support member 26Y is located at the second support position.

2.3.7 Rod The rod 27Y extends along the second axis A2. The rod 27Y has a cylindrical shape. The rod 27Y is inserted through the through hole 223 of the first gear 22Y and the through hole 233 of the second gear 23Y. Thereby, the rod 27Y penetrates the first gear 22Y and the second gear 23Y. The rod 27Y extends from the support member 26Y. The rod 27Y may be configured as a member different from the support member 26Y and attached to the support member 26Y. The rod 27Y is movable in the axial direction together with the support member 26Y.

  Specifically, as shown in FIG. 3, the rod 27Y is located at the advanced position when the support member 26Y is located at the first support position. The rod 27Y presses the first end 281 of the lever 28Y when positioned at the advanced position. The first end 281 will be described later.

  Further, as shown in FIG. 5, the rod 27Y is located at the retracted position when the support member 26Y is located at the second support position. When the rod 27Y is positioned at the retracted position, the rod 27Y releases the pressure on the first end 281 of the lever 28Y.

2.3.8 Shaft The shaft 29Y is rotatable about the third axis A3 as shown in FIGS. The third axis A3 extends in the axial direction. The shaft 29Y extends along the third axis A3. The shaft 29Y has a cylindrical shape.

2.3.9 Cam The cam 30Y can rotate about the third axis A3 together with the shaft 29Y. The cam 30Y can rotate between a pressing position shown in FIG. 4 and a pressing release position shown in FIG. As shown in FIGS. 3 and 4, the cam 30Y has a first plane 301A, a second plane 301B, and an inclined surface 301C.

  The first plane 301A extends in a direction intersecting the third axis A3. Preferably, the first plane 301A extends in a direction orthogonal to the third axis A3. Specifically, the first plane 301A extends in the circumferential direction of the cam 30Y.

  As shown in FIGS. 5 and 6, the first plane 301A faces the support member 26Y located at the second support position in the axial direction when the cam 30Y is located at the press release position. That is, when the cam 30Y is positioned at the press release position, the cam 30Y releases the press against the support member 26Y and allows the support member 26Y to be positioned at the second support position. The first plane 301A may contact the support member 26Y located at the second support position when the cam 30Y is located at the press release position.

  As shown in FIGS. 3 and 4, the second plane 301B is located at a position different from the first plane 301A in the circumferential direction of the cam 30Y. The second plane 301B is located at a distance from the first plane 301A in the circumferential direction of the cam 30Y. Further, the second plane 301B is located at a position different from the first plane 301A in the axial direction. The second plane 301B is located at an interval from the first plane 301A in the axial direction. The second plane 301B is located closer to the first gear 22Y than the first plane 301A in the axial direction. The second plane 301B extends in a direction intersecting the third axis A3. Preferably, the second plane 301B extends in a direction orthogonal to the third axis A3. Specifically, the second plane 301B extends in the circumferential direction of the cam 30Y. The second plane 301B is parallel to the first plane 301A. When the cam 30Y is positioned at the pressing position, the second plane 301B contacts the support member 26Y positioned at the first support position in the axial direction. That is, when the cam 30Y is positioned at the pressing position, the cam 30Y presses the support member 26Y and positions the support member 26Y at the first support position.

  The inclined surface 301C is located between the first plane 301A and the second plane 301B in the circumferential direction of the cam 30Y. The inclined surface 301C is inclined with respect to the first plane 301A and the second plane 301B. The inclined surface 301C connects the first plane 301A and the second plane 301B. The inclined surface 301C approaches the first gear 22Y in the axial direction as it approaches the second plane 301B from the first plane 301A. When the cam 30Y rotates from the pressing release position (see FIG. 6) to the pressing position (see FIG. 4), the support member 26Y moves from the second support position to the first support position by sliding on the inclined surface 301C. To do.

  More specifically, the cam 30 </ b> Y includes a disc 51 and a rib 52.

  The disc 51 has a first plane 301A. The disc 51 extends in a direction intersecting the third axis A3. Preferably, the disc 51 extends in a direction orthogonal to the third axis A3.

  The rib 52 has a second plane 301B and an inclined surface 301C. The rib 52 is provided in a part of the cam 30Y in the circumferential direction of the cam 30Y. The rib 52 protrudes from the disc 51 in the axial direction. The rib 52 extends in the circumferential direction of the cam 30Y. The rib 52 is located around the shaft 29Y. The rib 52 is located around the third axis A3.

2.3.10 Third gear The third gear 31Y receives power from the motor 11 and can rotate about the third axis A3. Power from the motor 11 is transmitted to the third gear 31Y by a gear train (not shown). The third gear 31Y is a spur gear. The third gear 31Y may be a bevel gear.

2.3.11 Electromagnetic clutch The electromagnetic clutch 32Y can be switched to an on state or an off state. When the electromagnetic clutch 32Y is in the on state, the shaft 29Y can rotate together with the third gear 31Y. That is, when the electromagnetic clutch 32Y is in the on state, power is transmitted from the third gear 31Y to the shaft 29Y, and the cam 30Y rotates. In addition, when the electromagnetic clutch 32Y is in the off state, the third gear 31Y can rotate with the shaft 29Y stopped. That is, when the electromagnetic clutch 32Y is in the off state, the transmission of power from the third gear 31Y to the shaft 29Y is released, and the rotation of the cam 30Y is stopped.

  As shown in FIG. 6, the electromagnetic clutch 32Y is turned on for a predetermined time in a state where the cam 30Y is located at the pressure release position, and then turned off, thereby bringing the cam 30Y into the pressure release position (FIG. 6). From the reference position) to the pressing position (see FIG. 4).

  Further, as shown in FIG. 4, the electromagnetic clutch 32Y is turned on for a predetermined time in a state where the cam 30Y is located at the pressing position, and then turned off, thereby pressing the cam 30Y (see FIG. 4). From the reference) to the pressure release position (see FIG. 6).

  Specifically, the electromagnetic clutch 32 </ b> Y includes a stator 321, a rotor 322, and an armature 323. The stator 321 is fixed to the image forming apparatus 1. The rotor 322 is rotatable with respect to the stator 321. The rotor 322 is attached to the shaft 29Y. The armature 323 can rotate with respect to the stator 321 together with the rotor 322 when the electromagnetic clutch 32Y is in an on state. Further, the armature 323 can rotate with respect to the stator 321 independently of the rotor 322 when the electromagnetic clutch 32Y is in the OFF state. The armature 323 is attached to the third gear 31Y.

2.3.12 Lever The lever 28Y is rotatable about the fourth axis A4 as shown in FIGS. The fourth axis A4 extends in a direction that intersects the axial direction. Preferably, the fourth axis A4 extends in a direction orthogonal to the axial direction. The lever 28Y is movable between a lever pressing position (see FIGS. 5 and 6) and a lever pressing release position (see FIGS. 3 and 4). The lever 28Y is pressed by a spring (not shown) so as to rotate about the fourth axis A4 from the lever pressing release position toward the lever pressing position.

  As shown in FIGS. 3 and 4, the lever 28Y is positioned at the lever pressing release position by being pressed by the rod 27Y with the support member 26Y positioned at the first support position. Specifically, the lever 28 </ b> Y has a first end 281 and a second end 282. The first end 281 is located away from the fourth axis A4. The second end 282 is located on the opposite side of the first end 281 with respect to the fourth axis A4. The second end 282 is located away from the fourth axis A4. When the support member 26Y moves from the second support position (see FIGS. 5 and 6) to the first support position (see FIGS. 3 and 4), the first end 281 is pressed by the rod 27Y. As a result, the lever 28Y moves from the lever pressing position to the lever pressing release position against the pressing force of a spring (not shown). When the lever 28Y is positioned at the lever pressing release position, the second end 282 is separated from the separation member 12Y. That is, when the lever 28Y is at the lever pressing release position, the lever 28Y releases the pressing on the separating member 12Y. Accordingly, the lever 28Y allows the separation member 12Y to be positioned at the first position (see FIG. 3). As described above, when the separation member 12Y is located at the first position, the developing roller 10Y is located at the contact position. That is, when the rod 27Y presses the lever 28Y from the lever pressing position toward the lever pressing release position, the developing roller 10Y moves from the separated position to the contact position. That is, when the rod 27Y is located at the advanced position, the rod 27Y positions the developing roller 10Y at the contact position.

  Further, as shown in FIGS. 5 and 6, the lever 28Y is released from the pressure by the rod 27Y in a state where the support member 26Y is positioned at the second support position, and the lever 28Y is pressed by a spring pressure (not shown). Located in the pressing position. Specifically, when the support member 26Y moves from the first support position (see FIG. 4) to the second support position (see FIG. 6), the rod 27Y releases the pressure on the first end 281. The rod 27Y may be separated from the first end 281. Thereby, the lever 28Y rotates about the fourth axis A4 from the lever pressing release position toward the lever pressing position by the pressing force of a spring (not shown). When the lever 28Y is positioned at the lever pressing position, the second end 282 presses the separation member 12Y. That is, when the lever 28Y is in the lever pressing position, the lever 28Y presses the separation member 12Y from the first position (see FIG. 3) to the second position (see FIG. 5). Thereby, the lever 28Y positions the separating member 12Y at the second position. As described above, when the separation member 12Y is located at the second position, the developing roller 10Y is located at the separation position. That is, when the rod 27Y releases the pressure on the lever 28Y, the developing roller 10Y moves from the contact position to the separated position. That is, the rod 27Y moves the developing roller 10Y between the contact position and the separation position. Further, when the rod 27Y is positioned at the retracted position, the rod 27Y positions the developing roller 10Y at the separated position.

3. Operation of Switching Mechanism Next, the operation of the switching mechanism 13Y will be summarized with reference to FIG. 3 and FIG.

  As shown in FIG. 3, when the switching mechanism 13Y is in the power transmission state, the support member 26Y is positioned at the first support position when the cam 30Y is positioned at the pressing position. When the support member 26Y is positioned at the first support position, the second gear 23Y is positioned at the transmission position. When the second gear 23Y is positioned at the transmission position, both the first gear 22Y and the second gear 23Y can rotate. As a result, the power from the motor 11 is sequentially transmitted through the idle gear 25Y, the second gear 23Y, the first gear 22Y, and the joint 21Y, and is input to the developing cartridge 7Y (see FIG. 1). Then, the developing roller 10Y rotates.

  Further, when the support member 26Y is positioned at the first support position, the lever 28Y is positioned at the lever pressing release position by being pressed by the rod 27Y. Further, when the lever 28Y is positioned at the pressing release position, the separation member 12Y is positioned at the first position. As a result, the developing roller 10Y is positioned at the contact position (see FIG. 1).

  When the switching mechanism 13Y is switched from the power transmission state (see FIG. 3) to the transmission release state (see FIG. 5), the electromagnetic clutch 32Y is switched from the off state to the on state.

  Then, the cam 30Y rotates together with the third gear 31Y from the pressing position (see FIG. 3) to the pressing release position (see FIG. 5). The electromagnetic clutch 32Y is switched from the on state to the off state at the timing when the cam 30Y is positioned at the pressing release position. Thereby, as shown in FIG. 5, the cam 30Y is located in the press release position.

  When the cam 30Y is positioned at the press release position, the support member 26Y is positioned at the second support position. When the support member 26Y is located at the second support position, the second gear 23Y is located at the release position. When the second gear 23Y is located at the release position, the transmission of power from the second gear 23Y to the first gear 22Y is released, and the rotation of the first gear 22Y and the joint 21Y stops. As a result, the rotation of the developing roller 10Y stops.

  Further, when the support member 26Y is positioned at the second support position, the lever 28Y is positioned at the lever pressing position by releasing the pressing of the rod 27Y against the lever 28Y. Further, when the lever 28Y is positioned at the lever pressing position, the separation member 12Y is positioned at the second position. As a result, the developing roller 10Y is positioned at the separation position (see FIG. 2).

  When the switching mechanism 13Y is switched from the transmission release state (see FIG. 5) to the power transmission state (see FIG. 3), the electromagnetic clutch 32Y is switched from the off state to the on state, and then the cam 30Y is moved to the pressed position. At the timing of positioning, the on state is switched to the off state.

  Then, when the second gear 23Y is positioned at the transmission position, the developing roller 10Y rotates, and when the lever 28Y is positioned at the lever pressing release position, the developing roller 10Y is positioned at the contact position.

4). According to the image forming apparatus 1, as shown in FIG. 3, when the cam 30Y is positioned at the pressing position and the support member 26Y is positioned at the first support position, the rod 27Y is positioned at the advanced position, and the lever 28Y is located at the lever pressing release position. Thereby, the switching mechanism 13Y can position the developing roller 10Y at the contact position.

  Further, when the support member 26Y is located at the first support position, the second gear 23Y is located at the transmission position. When the second gear 23Y is located at the transmission position, the second gear 23Y rotates together with the first gear 22Y. Thereby, the power from the motor 11 can be transmitted to the joint 21Y via the second gear 23Y and the first gear 22Y.

  As a result, the developing roller 10Y can be rotated with the developing roller 10Y positioned at the contact position.

  On the other hand, as shown in FIG. 5, when the cam 30Y is positioned at the pressing release position and the supporting member 26Y is positioned at the second supporting position, the rod 27Y is positioned at the retracted position and the lever 28Y is positioned at the lever pressing position. To position. Thereby, the switching mechanism 13Y can position the developing roller 10Y in the separated position.

  Further, when the support member 26Y is located at the second support position, the second gear 23Y is located at the release position. When the second gear 23Y is located at the release position, the second gear 23Y rotates with the first gear 22Y stopped. Thereby, the transmission of power from the second gear 23Y to the first gear 22Y can be released, and the transmission of power from the motor 11 to the joint 21Y can be released.

  As a result, the rotation of the developing roller 10Y can be stopped with the developing roller 10Y positioned at the separated position.

  Further, according to the image forming apparatus 1, as shown in FIG. 5, the electromagnetic clutch 32Y is turned on for a predetermined time with the cam 30Y positioned at the pressing release position, and then turned off. The cam 30Y can be rotated from the pressing release position (see FIG. 5) to the pressing position (see FIG. 3).

  Therefore, the developing roller 10Y can be positioned at the contact position and the developing roller 10Y can be rotated by a simple operation of switching the electromagnetic clutch 32Y between the on state and the off state.

  Similarly, the electromagnetic clutch 32Y is turned on for a predetermined time in a state where the cam 30Y is located at the pressing position (see FIG. 3), and then turned off, so that the cam 30Y is moved to the pressing position (FIG. 3). It can be rotated from the press release position (see FIG. 5).

  For this reason, the developing roller 10Y can be positioned at the separated position and the rotation of the developing roller 10Y can be stopped by a simple operation of switching the electromagnetic clutch 32Y between the on state and the off state.

  Further, according to the image forming apparatus 1, as shown in FIGS. 3 and 5, the separation member 12Y is moved from the first position to the second position by moving the support member 26Y from the first support position to the second support position. The second gear 23Y can be moved from the transmission position to the release position.

  Therefore, the rotation of the developing roller 10Y can be stopped at the timing when the developing roller 10Y is positioned at the separation position.

  Further, according to the image forming apparatus 1, as shown in FIGS. 3 and 5, the first gear 22Y and the second gear 23Y can rotate about the second axis A2, and the rod 27Y moves on the second axis A2. And extends through the first gear 22Y and the second gear 23Y.

  Therefore, the rod 27Y, the first gear 22Y, and the second gear 23Y can be collectively arranged, and the switching mechanism 13Y can be downsized.

5. Modified Example The developing roller 10Y may be located at the separation position when the separation member 12Y is located at the first position, and may be located at the contact position when the separation member 12Y is located at the second position.

  Although not shown, the image forming apparatus 1 includes one drum unit having four photosensitive drums 4Y, 4M, 4C, and 4K, and four developing cartridges 7Y, 7M, 7C, and 7K that can be attached to the drum unit. Also good. In this case, the separation members 12Y, 12M, 12C, and 12K may be provided in the drum unit.

  Although not shown, the image forming apparatus 1 includes a photosensitive drum 4Y and a drum cartridge 100Y to which the developing cartridge 7Y can be mounted. A drum cartridge 100M including the photosensitive drum 4M and to which the developing cartridge 7M can be mounted; There may be provided a drum cartridge 100C having the photosensitive drum 4C to which the developing cartridge 7C can be mounted, and a drum cartridge 100K having the photosensitive drum 4K to which the developing cartridge 7K can be mounted. In this case, the separation member 12Y is provided in the drum cartridge 100Y, the separation member 12M is provided in the drum cartridge 100M, the separation member 12C is provided in the drum cartridge 100C, and the separation member 12K is provided in the drum cartridge 100K. May be.

  Although not shown, the image forming apparatus 1 includes a process cartridge 101Y having a photosensitive drum 4Y and a developing roller 10Y, a process cartridge 101M having a photosensitive drum 4M and a developing roller 10M, a photosensitive drum 4C, and a developing roller 10C. And a process cartridge 101K having a photosensitive drum 4K and a developing roller 10K. In this case, the separation member 12Y is provided in the process cartridge 101Y, the separation member 12M is provided in the process cartridge 101M, the separation member 12C is provided in the process cartridge 101C, and the separation member 12K is provided in the process cartridge 101K. May be.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 4Y Photosensitive drum 4M Photosensitive drum 4C Photosensitive drum 4K Photosensitive drum 10Y Developing roller 10M Developing roller 10C Developing roller 10K Developing roller 11 Motor 12Y Separation member 13Y Switching mechanism 21Y Joint 22Y First gear 23Y Second gear 24Y Spring 26Y Support Member 27Y Rod 28Y Lever 29Y Shaft 30Y Cam 31Y Third gear 32Y Electromagnetic clutch 41Y Joint gear 322 Rotor 323 Armature A1 First axis A2 Second axis A3 Third axis

Claims (4)

A photosensitive drum;
A developing roller that is movable between a contact position that contacts the photosensitive drum and a separation position that is separated from the photosensitive drum;
A motor,
A joint for transmitting power to the developing roller, the joint having a joint gear and rotatable about a first axis extending in the axial direction;
A first gear meshing with the joint gear, the first gear being rotatable about a second axis extending in the axial direction;
A second gear that receives power from the motor, the transmission position being rotatable with respect to the second shaft together with the first gear, and being rotatable with respect to the second shaft while the first gear is stopped; A second gear movable in the axial direction between the release position;
A spring located between the first gear and the second gear in the axial direction and pressing the second gear located at the transmission position toward the release position;
A support member for supporting the second gear, the support member being movable in the axial direction together with the second gear, wherein the second gear is located at the transmission position; and A support member movable between a second support position where the gear is located at the release position;
A rod for moving the developing roller between the contact position and the separation position, the rod being movable in the axial direction together with the support member, wherein the support member is positioned at the first support position. In this case, the developing roller is positioned at the advancing position where the developing roller is positioned at the contact position, and when the support member is positioned at the second supporting position, the developing roller is positioned at the retracted position where the developing roller is positioned at the separation position. A rod extending along the second axis and passing through the first gear and the second gear;
A shaft rotatable about a third axis extending in the axial direction, the shaft extending along the third axis;
A cam that is rotatable about the third axis together with the shaft, pressing the support member, positioning the support member at the first support position, and releasing the pressure on the support member; A cam rotatable between a pressing release position allowing the member to be positioned at the second support position;
A third gear capable of rotating about the third shaft by receiving power from the motor;
An electromagnetic clutch comprising an armature attached to the third gear and a rotor attached to the shaft, wherein the shaft is rotatable together with the third gear, and the shaft is stopped when the shaft is stopped. An electromagnetic clutch that can be switched between an off state in which three gears can rotate, and is in the on state for a predetermined time with the cam positioned at the pressing release position, and then in the off state. By rotating the cam from the pressing release position to the pressing position, the cam is positioned at the pressing position, and is turned on for a predetermined time, and then turned off. An electromagnetic clutch for rotating a cam from the pressing position to the pressing release position;
An image forming apparatus comprising: A separation member for moving the development roller from the contact position to the separation position, a first position where the development roller is located at the contact position, and a second position where the development roller is located at the separation position. A spacing member movable in the axial direction between
The lever is movable between a lever pressing position that presses the spacing member from the first position to the second position and a lever pressing release position that releases the pressing against the spacing member, and the support member is the lever When the rod is pressed by the rod in the state of being in the first support position, the lever is released in the position of releasing the lever press, and in the state of the support member being in the second support position, the pressure by the rod is released. A lever positioned at the lever pressing position,
The image forming apparatus according to claim 1, further comprising: The image forming apparatus is in a power transmission state in which the developing roller is positioned at the contact position and power can be transmitted to the developing roller, or the developing roller is positioned at the separation position and power of the developing roller is It has a switching mechanism that can be switched to a transmission release state that releases transmission,
The switching mechanism includes the joint, the first gear, the second gear, the spring, the support member, the rod, the lever, the shaft, the cam, a third gear, and the electromagnetic clutch. The image forming apparatus according to claim 2.   The image forming apparatus according to claim 3, comprising four photosensitive drums, four developing rollers, and four switching mechanisms.

Images