JP4267052B2 - Color electrophotographic image forming apparatus - Google Patents

Description

  The present invention relates to a color electrophotographic image forming apparatus that supports a plurality of developing devices and uses a rotatable rotating support (rotary).

  2. Description of the Related Art Conventionally, a color electrophotographic image forming apparatus that supports a plurality of developing devices and uses a rotatable rotating support (rotary) is known. In the image forming apparatus, a configuration in which a pulse motor is independently used as a motor for rotating a rotary support is known (see Patent Document 1). This pulse motor is meshed with a gear having a large diameter attached to the rotary support via a plurality of gears. Then, by controlling the rotation of the pulse motor, each developing device supported by the rotating support is reliably moved to the developing position facing the photosensitive drum.

Japanese Patent Laying-Open No. 2005-227719 (FIGS. 1 and 12)

  In the conventional image forming apparatus, as described above, the stop position of the rotary support is controlled by controlling the rotation speed of the pulse motor that can control the rotation speed. Here, the pulse motor and the brushless motor which can similarly control the rotation speed are expensive and large. Therefore, it becomes a factor of cost increase and space increase.

  An object of the present invention is to provide a color electrophotographic image forming apparatus that is low in cost and space efficient as compared with the case of using a pulse motor or a brushless motor capable of controlling the number of rotations.

  Another object of the present invention is to provide a color electrophotographic apparatus capable of reliably moving each developing device supported by a rotating support to a developing position without providing a dedicated motor for rotating the rotating support. An image forming apparatus is provided.

  Another object of the present invention is to provide color electronics capable of rotating a rotational force receiving member (for example, a conveyance roller, a fixing device, a transfer belt, etc.) with the rotational force of a motor for rotating a rotary support. A photographic image forming apparatus is provided.

  Another object of the present invention is to provide a color electrophotographic image forming apparatus in which the size and cost of the apparatus are reduced as compared with the case of using a pulse motor or a brushless motor capable of controlling the rotation speed. .

In order to achieve the above object, a typical configuration of the present invention is a color electrophotographic image forming apparatus for forming an image on a recording medium, including an electrophotographic photosensitive member and a rotatable rotary support, A rotating support for supporting a plurality of developing devices for developing an electrostatic latent image formed on the photosensitive member, a rotating support gear member rotating integrally with the rotating support, and the rotating support A first transmission gear member that engages with the gear member, a rotating member that rotates integrally with the first transmission gear member, and an engaging portion that is provided on the rotating member to stop the rotation of the rotating member; An engagement member that is detachably engaged, and a second transmission gear member that transmits the rotational force of the drive member that rotates in one direction in response to the rotational force from the motor, and The engaging member engages with the engaging portion, and the rotation When the rotation of the material is stopped, the second transmission gear member is stopped by stopping the second transmission gear member from receiving the rotational force from the drive member, and the second transmission gear member is rotated by the rotation of the rotating member. In which the rotational force is transmitted from the drive member to rotate, and in the activated state, the rotating support is rotated, and the developing device develops the electrostatic latent image. sequentially moved into position, the drive member is rotated by the rotational force from the motor, the rotational force is transmitted to the rotating support via the second transmission gear member and the rotary support gear member, said The rotational support is rotated, and the rotational force from the motor is transmitted to the rotational force transmitted member to rotate the rotational force transmitted member, and the rotational force transmitted member includes at least the rotational force transmitted member. Conveying rollers for conveying the recording medium, the fixing of the developer image transferred to the recording medium to fix to the recording medium apparatus, and wherein the a one of the electrophotographic photosensitive member.

  According to the present invention, it is possible to provide a color electrophotographic image forming apparatus with low cost and good space efficiency as compared with the case of using a pulse motor or a brushless motor capable of controlling the number of rotations.

  In addition, according to the present invention, color electrophotography that can reliably move each developing device supported by the rotating support to the developing position without providing a dedicated motor for rotating the rotating support. An image forming apparatus can be provided.

  According to the present invention, a color electrophotographic image capable of rotating a rotational force receiving member (for example, a conveyance roller, a fixing device, a transfer belt, etc.) with a rotational force of a motor for rotating a rotary support. A forming apparatus can be provided.

  In addition, according to the present invention, it is possible to provide a color electrophotographic image forming apparatus in which the size and cost of the apparatus are reduced compared to the case of using a pulse motor or a brushless motor.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, exemplary embodiments of the invention will be described with reference to the drawings. However, the dimensions, materials, shapes, and relative arrangements of the components described in the following embodiments should be changed as appropriate according to the configuration of the apparatus to which the present invention is applied and various conditions. Therefore, unless specifically stated otherwise, the scope of the present invention is not intended to be limited thereto.

[First Embodiment]
A color electrophotographic image forming apparatus according to a first embodiment will be described. Here, as a color electrophotographic image forming apparatus, a color laser beam printer including four developing devices is illustrated. FIG. 1 is a sectional view of a color laser beam printer.

  First, the image forming operation of this color laser beam printer will be described. As shown in FIG. 1, the image forming apparatus includes a drum-shaped electrophotographic photosensitive member (hereinafter referred to as a photosensitive drum) 2. Around the photosensitive drum 2, a charging roller 3, an exposure device 4, V (V is a natural number, here 4) developing devices 18a to 18d, and a cleaning device 6 are arranged. The charging roller 3 is charging means for uniformly charging the photosensitive drum 2. The exposure device 4 is an exposure means for forming an electrostatic latent image by irradiating the photosensitive drum 2 with laser light in accordance with image information. The developing devices 18a to 18d are developing means for developing the latent image formed on the photosensitive drum 2 with a developer of a corresponding color to visualize the latent image. In the present embodiment, the corresponding colors are yellow, magenta, cyan, and black. The developing device 18a contains a yellow developer (not shown). The developing device 18b contains a magenta developer (not shown). The developing device 18c contains a cyan developer (not shown). The developing device 18d contains a black developer (not shown). That is, the developing devices 18a to 18d develop the latent image formed on the photosensitive drum 2 using a developer. The cleaning device 6 is a cleaning unit that removes residual developer on the photosensitive drum 2.

  First, the photosensitive drum 2 is rotated in the arrow direction (counterclockwise) in FIG. 1 in synchronization with the rotation of the intermediate transfer belt (rotational force transmitted member) 7. Then, the surface of the photosensitive drum 2 is uniformly charged by the charging roller 3. At the same time, the photosensitive drum 2 is irradiated with light of a yellow image by the exposure device 4. As a result, a yellow electrostatic latent image is formed on the photosensitive drum 2.

  Simultaneously with the formation of the electrostatic latent image, a rotary (rotary support) 105 that supports and rotates the four developing devices 18a to 18d is rotated about a shaft 105b by a drive transmission mechanism (described later). As a result, the rotary 105 rotates to place the yellow developing device 18a at the developing position 18Y facing the photosensitive drum 2 (FIG. 4). The rotary 105 is a rotatable rotating support. The rotary 105 supports a plurality of developing devices 18a to 18d for developing the electrostatic latent image formed on the photosensitive drum 2 at equal intervals in the C direction (FIGS. 2 and 4). Yes. However, the rotary 105 may not support the plurality of developing devices 18a to 18d at equal intervals. For example, when the sizes of the developing devices are different, they may be supported at intervals corresponding to the size of the developing device. In this case, the rotary 105 rotates at an angle corresponding to the size of the developing device.

  Then, a voltage having the same polarity as the charging polarity of the photosensitive drum 2 and substantially the same potential is applied to the developing roller 182a so that the yellow developer adheres to the latent image formed on the photosensitive drum 2. Thus, development is performed by attaching a yellow developer to the latent image. That is, a yellow developer image is formed on the photosensitive drum 2.

  Thereafter, a voltage having a polarity opposite to that of the developer is applied to the primary transfer roller 81 disposed inside the intermediate transfer belt 7. As a result, the yellow developer image formed on the photosensitive drum 2 is primarily transferred onto the intermediate transfer belt 7.

  When the primary transfer of the yellow developer image is completed as described above, the developing devices (18b to 18d) for magenta, cyan, and black are sequentially positioned at the developing position 18Y by the rotation of the rotary 105. Similarly to the case of yellow, latent image formation, development, and primary transfer are sequentially performed for each of magenta, cyan, and black. Then, four color developer images are superimposed on the intermediate transfer belt 7.

  During this time, the secondary transfer roller 82 is not in contact with the transfer belt 7. At this time, the cleaning unit 9 for removing the residual developer on the transfer belt 7 is also not in contact with the transfer belt 7.

  On the other hand, sheets S as recording media are stacked and stored in a feeding cassette 51 provided at the lower part of the apparatus. Then, the sheet is separated and fed from the cassette 51 by the rotation of the feeding roller 52. The fed sheet S is fed to a registration roller pair (conveying roller pair, rotational force transmitted member) 53. The registration roller pair 53 sends out the fed sheet S between the transfer belt 7 and the transfer roller 82. Here, the transfer roller 82 is in pressure contact with the transfer belt 7 (the state shown in FIG. 1).

  Further, a voltage having a polarity opposite to that of the developer is applied to the transfer roller 82. As described above, the four color developer images superimposed on the transfer belt 7 are collectively transferred (secondary transfer) onto the surface of the conveyed sheet S.

  The sheet S on which the developer image is transferred is sent to a fixing device (fixing means, fixing device, rotational force receiving member) 54. In the fixing device 54, the sheet S is heated and pressed. Then, the developer image is fixed on the sheet S. As a result, a color image is formed on the sheet S. Then, the sheet S passes through the fixing device 54 and is discharged to the discharge portion of the upper cover 55.

  Here, a drive transmission mechanism for rotating the rotary 105 will be described with reference to FIGS. 2 and 3. 2 is a front view showing the configuration of the drive transmission mechanism, and FIG. 3 is a right side view of FIG. 2 viewed from the right. However, the main body frames 171 and 172 shown in FIG. 3 are not shown in FIG. In FIG. 3, the photosensitive drum 2, the transfer belt 7 and the transfer roller 81 shown in FIG. 2 are not shown.

  The drive transmission mechanism shown in FIGS. 2 and 3 rotates the rotary 105 about the shaft 105b. Accordingly, the drive transmission mechanism sequentially moves the four developing devices 18 a to 18 d supported by the rotary 105 to the developing position 18 </ b> Y facing the photosensitive drum 2.

  Hereinafter, the configuration of the drive transmission mechanism will be described.

  The drive gear (drive member) 173 is rotatably supported with respect to the image forming apparatus main body A. The gear 173 receives a rotational force from the motor M (drive source) and rotates in one direction (here, the direction of arrow A in FIG. 2). The rotational force transmission mechanism that transmits rotational force from the motor M to the gear 173 has the following configuration. For example, a gear divided from a pair of registration rollers (conveying roller pair) 53 (rotational force transmission mechanism M1, FIG. 4) or a gear that transmits rotational force to the photosensitive drum 2 ( Any configuration that can transmit rotational force, such as a configuration divided from the rotational force transmission mechanism M2, FIG. 4), can be used as appropriate. Further, a configuration in which teeth are divided from a gear or the like (rotational force transmission mechanism M4, FIG. 4) that transmits rotational force to the fixing device 54 may be used. In this embodiment, the rotational force from the brush motor M whose rotational speed cannot be controlled is transmitted to the gear 173 via the rotational force transmission mechanism M3 (FIG. 3).

  Here, the rotational force transmission mechanisms M <b> 1 to M <b> 4 are not limited to gear trains, and can be applied to any member that can transmit rotational force, such as a belt.

  Here, the rotational force receiving member that rotates by receiving the rotational force from the motor M is not limited to the above configuration. The rotational force receiving member includes at least a conveyance roller (registration roller) 53 that conveys the sheet S, a fixing device 54 that fixes the developer image transferred onto the sheet S, and the photosensitive drum 2. One of them.

  Further, examples of the rotational force transmission mechanism for transmitting the rotational force from the motor M to the rotational force transmitted member include rotational force transmission mechanisms M1, M2, and M3.

  Further, the motor M is not limited to a brush motor, and for example, a stepping motor, a brush DC motor, a brassless DC motor, or the like can be applied. According to the present embodiment, although the rotational speed cannot be controlled, each of the motors which are inexpensive compared with the pulse motor having the same output can be applied. Also, these motors are smaller than pulse motors if they have the same output. Therefore, according to the present embodiment, the advantages of these motors can be effectively utilized.

  The rotary 105 holds the developing devices 18a to 18d and is rotatably attached to the main body frames 171 and 172. The developing devices 18 a to 18 d may be a fixed type that is fixed to the rotary 105 or a detachable type that can be detached from the rotary 105. In this embodiment, the developing device employs a developing cartridge that is detachably attached to the rotary 105. Since the developer cartridge is detachable from the rotary 105 by the user, maintenance is easy. A rotary gear 105 a is provided on the outer periphery of the rotary 105. The gear 105 a rotates integrally with the rotary 105. The gear 105a is a rotation support gear member having the number of teeth Y (Y is a natural number). A shaft 108 provided rotatably with respect to the apparatus main body A is provided with a rotary drive gear 104 by a parallel pin or the like. The gear 104 is a transmission gear (first transmission gear member) having the number of teeth X (X is a natural number) that transmits the rotational force from the drive gear 173 rotating in one direction. The gear 105a is engaged with (engaged with) the gear 104. Therefore, the rotary 105 rotates in synchronization with the gear 104.

  The developing devices 18a to 18d supported by the rotary 105 have developing rollers 182a to 182d, respectively. The developing rollers 182a to 182d are elastic bodies and have a predetermined elastic force. The developing rollers 182a to 182d develop the latent image while being in pressure contact with the photosensitive drum 2.

  The shaft 108 is provided with a trigger cam 101 by a parallel pin or the like. For this reason, the cam 101 and the shaft 108 rotate in synchronization. The cam 101 is a rotating member having M (M is a natural number, here 1) claw portions (engagement portions) 101a that can be engaged with an electric actuator (described later). The cam (rotating member) 101 rotates integrally with the gear 104.

  The trigger spring 103 is, for example, a tension spring. One end of the spring 103 is fixed to the apparatus main body A, and the other end is rotatably provided on the cam 101. The spring 103 is an urging member (elastic member) that urges the cam 101 in the rotation direction (here, the arrow B direction in FIG. 2).

  The solenoid (engagement member) 102 is fixed to the apparatus main body A. The solenoid 102 locks a claw portion (engagement portion) 101 a provided on the cam 101. This prevents the cam 101 from rotating in the direction of arrow B (FIG. 2) due to the elastic force of the spring 103. Here, the solenoid 102 is detachably engaged with a claw portion (engagement portion) 101 a provided on the cam 101 in order to stop the rotation of the cam 101.

  Further, a voltage can be applied to the solenoid 102 from a control unit C (FIG. 4) as a control means. The solenoid 102 is an electric actuator (engagement member) that is turned ON / OFF by application of a voltage. When a voltage is applied from the unit C to the solenoid 102, the solenoid 102 moves away from the claw portion 101a. As a result, the cam 101 is rotated in the arrow B direction by the elastic force of the spring 103. When the voltage to the solenoid 102 is turned off, the solenoid 102 engages with the claw portion 101a. Thereby, the rotation of the cam 101 is restricted.

  The shaft 108 is provided with a missing gear () 106. The missing tooth gear 106 is fixed to the side portion of the cam 101. That is, in this embodiment, the missing gear 106 and the trigger cam 101 are integrally formed. The missing gear 106 is not a perfect gear. As shown in FIG. 2, in the state where the rotation of the cam 101 is restricted by the solenoid 102, the teeth of the missing gear 106 are partially cut (missed teeth portion) so as not to mesh with the gear 173. That is, the gear 106 is M (one in this case) facing the drive gear 173 in a state where the gear 106 a meshable with the gear 173 and the solenoid 102 are engaged with the claw 101 a of the trigger cam 101. And a missing tooth portion 106b. The gear (second transmission gear member) 106 receives the rotational force from the motor M and transmits the rotational force of the gear (drive member) 173 that rotates in one direction to the cam 101.

  Therefore, the cam 101, the drive gear 104, the toothless gear 106, and the shaft 108 are integrated and can rotate around the shaft 108. Each member described above constitutes a drive transmission mechanism.

  Further, the drive transmission mechanism is set so that the values X, M, Y, and V of the natural numbers of the members described above satisfy a relationship in which (X / M) is a divisor of (Y / V). .

Here, when a voltage is applied to the solenoid 102, the engagement of the solenoid 102 with the claw portion 101a of the trigger cam 101 is released. As a result, the regulating force received by the cam 101 from the solenoid 102 is eliminated, and the cam 101 rotates in the direction of arrow B by the pulling force (biasing force, elastic force) of the spring 103. As a result, the toothless gear 106 synchronized with the cam 101 rotates, and the gear portion 106 a of the toothless gear 106 meshes with the drive gear 173. That is, by applying a voltage to the solenoid 102, the drive transmission mechanism rotates in the direction of arrow B in FIG. The time required for the drive transmission mechanism to make one rotation is t1, the time for applying a voltage to the solenoid 102 is t2, and the response time of the solenoid 102 is temporarily 0. Then, when t1> t2, the drive transmission mechanism makes one rotation. As a result, the cam 101 is locked by the solenoid 102 and stops rotating. That is, every time the solenoid 102 is disengaged from the claw 101a of the cam 101, the cam 101 rotates 1 / M in the direction of arrow B (one rotation here) . Further, when the solenoid 102 is engaged with the claw portion 101a, the cam 101 stops rotating.

  On the other hand, the gear 104 and the gear 105a mesh with each other. Therefore, as the gear 106 rotates, the rotary 105 also rotates in the direction of arrow C (FIG. 2). Here, the four-color developing devices (18a to 18d) are sequentially moved to the developing position 18Y (state shown in FIG. 2). Therefore, the number of teeth Y of the gear 105a is assumed to be four times the number of teeth X of the drive gear 104. For example, the number of teeth Y of the gear 105a is 80, and the number of teeth X of the drive gear 104 is 20. Note that the developing roller 182 is in pressure contact with the photosensitive drum 2 at the developing position 18Y.

At this time, when a voltage is applied to the solenoid 102 by t2 (<t1), the rotary 105 moves the next developing device 18b to the developing position 18Y and stops it at the developing position 18Y. Further, when the development of the developing device 18b is completed and development is performed by the developing device 18c, a voltage is again applied to the solenoid 102 by t2 (<t1). As a result, the developing device 18c is moved to the developing position 18Y and stopped at the developing position 18Y.

  On the other hand, as described above, the number of teeth Y of the gear 105a is four times the number of teeth X of the drive gear 104, but the multiple may be any natural number times four. For example, the number of teeth Y of the gear 105a is 120, and the number of teeth X of the drive gear 104 is 15 (120: 15 = 8: 18 times). In this case, a voltage is applied to the solenoid 102 twice for a time t2 (<t1) with a sufficient interval, or a voltage is applied to the solenoid 102 only for a time t2 where t1 <t2 <2 × t1. Thus, the developing devices 18a to 18d can be sequentially moved to the developing position 18Y. Further, it can be stopped at the developing position 18Y. The control of the voltage application to the solenoid 102 is performed by the control unit C (FIG. 4).

  The rotation of the rotary 105 that supports the developing devices 18a to 18d is stopped as follows. First, the application of voltage to the solenoid 102 is released. As a result, the solenoid 102 is engaged with the claw portion 101a. Then, as shown in FIG. 2, the rotation of the rotary 105 stops at a position where the missing tooth portion 106 b of the missing tooth gear 106 faces the drive gear 173.

  As described above, any drive transmission mechanism that is set so that the value of each natural number satisfies the relationship in which (X / M) is a divisor of (Y / V) can be configured as follows. . That is, every time the cam 101 rotates 1 / M, a rotational force (driving force) is transmitted from the driving gear 104 that rotates integrally with the cam 101 to the gear 105a. Then, the rotary 105 can be stopped by rotating it by an angle W which is a divisor of (360 / V).

  That is, according to the present embodiment, it is not necessary to provide a motor that can rotate the rotary 105 and control the rotational speed for accurately determining the position of the rotary 105 independently. According to the present embodiment, each developing device attached to the rotary 105 can be reliably moved to the developing position even when the motor capable of controlling the rotation speed is not provided independently. Further, it can be stopped at the development position. That is, the apparatus can be reduced in size and cost. Further, each developing device attached to the rotary can be reliably moved to the developing position without providing a motor capable of controlling the rotation speed independently. Further, it can be stopped at the development position.

  Further, the number of teeth Y of the gear 105a and the number of teeth X of the drive gear 104 are set to 4N times (N is a natural number of 2 or more) in this way. Accordingly, the rotary 105 can be stopped at a position where the developing rollers 182a to 182d and the photosensitive drum 2 are not in contact with each other, other than a position where the developing rollers 182a to 182d are in pressure contact with the photosensitive drum 2 (developing position).

  That is, in this embodiment, the rotary 105 rotates 45 degrees around the shaft 105b from the developing position 18Y and then stops. Accordingly, the developing devices 18 a to 18 d can stop at the standby position 18 </ b> X where the developing rollers 182 a to 182 d do not come into contact with the photosensitive drum 2. FIG. 4 shows a state in which the rotary 105 stops after rotating 45 degrees, and the developing device 18a moves from the developing position 18Y to the standby position 18X and then stops at the standby position 18X.

  In this case, the developing rollers 182a to 182d can stand by without contacting the photosensitive drum 2. Accordingly, it is possible to prevent the photosensitive drum 2 or the developing rollers 182a to 182d from being deteriorated in some way by the pressure contact between the developing roller and the photosensitive drum 2 other than during development.

  In addition, although a four-color developing device is assumed here, three or two colors may be used. In this case, the same effect can be obtained by setting the number of teeth Y of the gear 105a to 2 × P times (P is a natural number) and 3 × Q times (Q is a natural number) of the number of teeth X of the rotary drive gear 104. The same applies to five or more colors. Incidentally, three developing devices are attached to the rotary 105 in the case of three colors, and two developing devices are attached in the case of two colors.

  Furthermore, in FIG. 2, the claw part (engagement part) 101a of the trigger cam 101 is made into one place. However, as shown in FIG. 4, there may be a plurality of claw portions 101a at equal intervals (equal angles). For example, as shown in FIG. 4, there are two claw portions 101a and 101b, and there are two toothless portions 106b1 and 106b2 of the drive gear 104 corresponding to this. When the ratio of the number of teeth X of the drive gear 104 to the number of teeth Y of the rotary gear 105a is 1: 2, the rotary 105 can be rotated by ¼ rotation and stopped. That is, the four-color developing device as described above can be sequentially rotated to the developing position and stopped.

  Therefore, the number of teeth of the drive gear 104 is X, the number of teeth of the gear 105a is Y, and the number of the claw portions 101a of the cam 101 is M. Accordingly, the rotary 105 can be rotated and stopped at an angle (pitch) W that satisfies 360 / (X × M / Y) = W °. However, W must be a divisor of (360 / V) in order to stop each developing device of V color at the developing position.

As described above, according to the present embodiment, a rotational force transmission unit that can take a stopped state in which the transmission of rotational force from the motor M is stopped and an operating state in which the rotational force is transmitted from the motor M. X. Then, in the operating state, the rotational force transmission unit X receives the rotational force from the motor M, rotates the rotary 105 by a predetermined amount, and sequentially moves the developing devices 18a to 18d to the developing position 18Y. Here, the rotational force transmission unit X includes a gear 173, a gear 106, a gear 104, a gear 105 a, a cam 101, a solenoid 102, and a spring 103.

  In the developing state as shown in FIG. 2, unless the voltage is applied to the solenoid 102, the rotary 105 is restricted by the solenoid 102 so that it cannot rotate in the direction of arrow C (FIG. 2). The cam 101 is also biased in the direction opposite to the arrow C direction by the elastic force of the trigger spring 103. Therefore, the rotary 105 cannot rotate without a force that resists this elastic force. Of course, the elastic force of the spring 103 is sufficient to prevent the rotary 105 from rotating in the direction opposite to the arrow C direction. That is, in the development state shown in FIG. 2, the rotary 105 is in a fixed state, and development can be performed reliably.

[Second Embodiment]
Next, another embodiment of the drive transmission mechanism that rotates the rotary 105 will be described with reference to FIGS. 5 and 6. FIG. 5 is a front view showing a schematic configuration of the drive transmission mechanism, and FIG. 6 is a right side view of FIG. 5 viewed from the right direction. However, in FIG. 5, the main body frames 171 and 172 shown in FIG. 6 are not shown. In FIG. 6, the photosensitive drum 2, the transfer belt 7, and the transfer roller 81 shown in FIG. 5 are not shown. In the second and third embodiments, description and illustration of members having the same functions as those in the first embodiment are omitted.

  In the drive transmission mechanism according to the present embodiment, torque transmission means 111 is added, the toothless gear 106 is changed to the sliding gear 112, and the trigger spring 103 is eliminated compared to the above-described embodiment.

  The sliding gear 112 is rotatably provided with respect to the shaft 108 and is always meshed with the driving gear 173.

  The torque transmission unit 111 is, for example, a torque limiter. The torque transmitting means 111 is provided so as to be rotatable with respect to the shaft 108, and includes a fixed side (fixed portion) 111a and a sliding side (sliding portion) 111b. The fixed side 111 a is engaged with the sliding gear 112 so that it can rotate in synchronization with the sliding gear 112. The sliding side 111 b is engaged with the cam 101 so that it can rotate in synchronization with the trigger cam 101. The fixed side 111a and the sliding side 111b normally rotate in synchronism, but if a predetermined torque T or more is generated between them, the fixed side 111a and the sliding side 111b slip and do not rotate in synchronism.

  As described above, the sliding gear 112 receives a rotational force from the driving gear 173. Therefore, the sliding gear 112 rotates in the arrow B direction (in FIG. 5) together with the fixed side 111a. On the other hand, the sliding side 111b, the cam 101, the drive gear 104, and the shaft 108 receive a force that rotates in the direction of arrow B (FIG. 5) from the fixed side 111a. However, the claw portion 101 a of the cam 101 is locked by the solenoid 102. For this reason, the fixed side 111a and the sliding side 111b of the torque transmission means 111 are in a sliding state, the rotational force of the sliding gear 112 is cut off with respect to the cam 101, and the rotation of the drive transmission mechanism is stopped. .

  In this state, when a voltage is applied to the solenoid 102, the engagement of the solenoid 102 with the claw portion 101a is released. Then, the fixed side 111a and the sliding side 111b rotate in synchronization. Thereby, the rotational force of the sliding gear 112 is transmitted to the cam 101 and the drive transmission mechanism is rotated. That is, the cam 101, the drive gear 104, the shaft 108, the torque transmission means 111, and the sliding gear 112 can be rotated together in the arrow B direction (FIG. 5). Therefore, the rotary 105 can be rotated. Subsequent operations are the same as those in the above-described embodiment.

As described above, according to the present embodiment, a rotational force transmission unit that can take a stopped state in which the transmission of rotational force from the motor M is stopped and an operating state in which the rotational force is transmitted from the motor M. Y. Then, in the operating state, the rotational force transmission unit Y receives the rotational force from the motor M, rotates the rotary 105 by a predetermined amount, and sequentially moves the developing devices 18a to 18d to the developing position 18Y. Here, the rotational force transmission unit Y includes a gear 173, a gear 112, a gear 104, a gear 105 a, and a solenoid 102.

  According to this embodiment, the same effect as the above-described embodiment can be obtained.

  Further, when a predetermined torque T or more is applied between the fixed side 111a and the sliding side 111b, both slip. Thereby, for example, even when foreign matter enters the rotary 105 and the rotary 105 cannot rotate, when the rotary 105 is rotated by applying a voltage to the solenoid 102, the fixed side 111a and the sliding side 111b Slip. Thereby, the driving torque (rotational torque) from the driving source (not shown) is not transmitted more than T. Therefore, it is possible to prevent the apparatus main body from being broken.

[Third Embodiment]
Next, another form of the drive transmission mechanism for rotating the rotary 105 will be described with reference to FIGS. FIG. 7 is a front view showing a schematic configuration of the drive transmission mechanism, and FIG. 8 is a right side view of FIG. 7 viewed from the right direction. However, the photosensitive drum, intermediate transfer belt, primary transfer roller, etc. are not shown. Here, the rotation direction of the rotary 105 is opposite to that in the above-described embodiment, but there is no problem with development.

  The drive transmission mechanism shown in FIGS. 7 and 8 rotates the rotary 105. Thus, the four developing devices 18 a to 18 d supported by the rotary 105 are sequentially switched and moved to the developing position facing the photosensitive drum 2. Hereinafter, the configuration of the drive transmission mechanism will be described.

  The rotary 105 holds (attaches) the four developing devices 18 and is provided so as to be rotatable with respect to the main body frames 171 and 172. As described above, the four developing devices 18 may be fixed to or removable from the rotary 105. A rotary gear 126 is provided on the outer periphery of the rotary 105. The rotary gear 126 rotates integrally with the rotary 105. The gear 126 has a gear portion 126a that can mesh with the rotary drive gear 127 rotating in one direction. Further, the gear 126 has V missing tooth portions 126 b that face the drive gear 127 when the solenoid 102 is engaged with any of the claw portions 121 a to 121 d of the cam 121. Here, the gear 126 possesses four of the above-mentioned missing tooth portions 126b at an equal angle.

  The cam 121 as a rotating member is engaged with the rotary 105 so that it can rotate in synchronization with the rotary 105 (may be integrated), and V (here, four) claw portions (engaged) that can be engaged with the solenoid 102. Part) 121a-121d. Here, the cam 121 has the claw portions 121a to 121d arranged at an equal angle.

  The claw portions 121a to 121d of the cam 121 and the four missing tooth portions 126b of the gear 126 are set at positions corresponding to the development position.

  The biasing cam 122 is engaged with the cam 121 so that it can rotate in synchronization with the cam 121 (may be integrated). The urging cam 122 is a guide member having V (four in this case) guide portions 122a.

  The trigger lever 123 is a lever member that is engaged with the guide portion 122 a of the biasing cam 122. The lever 123 is rotatably provided on a rotation shaft 125 provided in the apparatus main body.

  The biasing spring 124 is a biasing member (elastic member) that biases the lever 123 to bias the cam 121 in the rotation direction (the direction of arrow D in FIG. 7). The biasing spring 124 is, for example, a tension spring, one end is fixed to the apparatus main body, and the other end is provided on the lever 123. The spring 124 gives a turning force to the lever 123. Thereby, the lever 123 urges the urging cam 122, the cam 121, and the rotary 105 in the arrow D direction (FIG. 7) by the elastic force (spring force) of the spring 124.

  The rotary drive gear (drive member) 127 receives a rotational force from a drive source (not shown), and always rotates in one direction (here, arrow F direction in FIG. 7). As described above, this drive source (not shown) is, for example, divided from a gear driving a conveyance roller (not shown) or from a gear driving the photosensitive drum 2. As long as it has a rotational force, it can be applied as appropriate.

  A drive transmission mechanism is constituted by the above-described members. In the drive transmission mechanism, the engagement of the solenoid 102 with the claw portions 121a to 121d of the cam 121 is released, and the gear portion 126a of the gear 126 that rotates in synchronization with the cam 121 becomes the drive gear 127 each time it is engaged. Mesh. Then, the drive transmission mechanism stops the rotary 105 after rotating the rotary 105 by an angle W of (360 / V).

  In the state shown in FIG. 7, the solenoid 102 is engaged with the claw portion 121 a of the cam 121. As a result, the missing tooth portion 126b of the gear 126 is located at a position facing the drive gear 127, and no rotational force is transmitted to the gear 126. Therefore, the rotation of the drive transmission mechanism is stopped. Further, in the state shown in FIG. 7, the developing roller 182 is pressed against the photosensitive drum (not shown) with an elastic force.

  In this state, when a voltage is applied to the solenoid 102 for a predetermined time, the engagement of the solenoid 102 with the claw portion 121a of the cam 121 is released. For this reason, the trigger lever 123 urges the urging cam 122 in the direction of arrow D (FIG. 7) by the elastic force (the urging force) of the urging spring 124. Accordingly, the cam 121 rotates so that the gear portion 126a of the gear 126 meshes with the drive gear 127. Thereby, the urging cam 122, the cam 121, and the rotary 105 urged by the trigger lever 123 are integrally rotated in the arrow D direction. Then, the gear part 126a meshes with the drive gear 127 and rotates to the next missing tooth part 126b. Thereafter, the cam 121 is locked to the solenoid 102, and the biasing cam 122, the cam 121, and the rotary 105 are stopped. That is, the rotary 105 moves the next developing device to the developing position and stops it.

As described above, according to the present embodiment, the solenoid 102 (engagement member) is engaged with the claw portion (engagement portion) 101a, and the rotation of the cam 101 (rotation member) is stopped. As a result, the gear (second transmission gear member) 106 stops receiving the rotational force from the gear (drive member) 173, and the cam 101 rotates to cause the gear 106 to rotate from the gear 173. And an operating state that rotates in response to the transmission. In the operating state, the rotary 105 is rotated by a predetermined amount to sequentially move the developing devices 18a to 18d to the developing position 18Y.

In addition, according to the present embodiment, the rotational force transmission unit Z that can take a stopped state in which the transmission of rotational force from the motor M is stopped and an operating state in which the rotational force is transmitted from the motor M is provided. . Then, in the operating state, the rotational force transmission unit Z receives the rotational force from the motor M, rotates the rotary 105 by a predetermined amount, and sequentially moves the developing devices 18a to 18d to the developing position 18Y. Here, the rotational force transmission unit Z includes a gear 127, a gear 126, a cam 121, a cam 122, and a solenoid 102.

  Even if configured as described above, the same effects as those of the above-described embodiment can be obtained. That is, the rotation of the rotary can be controlled without providing a drive motor capable of controlling the rotation speed independently.

  In this embodiment, the claw portion 121a and the missing tooth portion 126b are provided at four equal angles in order to sequentially move the four color developing devices to the developing position. However, these may be provided at 4 × N (N is a natural number) locations. Further, as described in the above-described embodiment, 3 × N (N is a natural number) in the case of three colors, and 2 × N (N is a natural number) in the case of two colors may be provided. The same applies to five or more colors.

  According to each embodiment described above, the control of the solenoid 102 is performed by the unit C.

  Moreover, according to each embodiment, as a member which transmits rotational force, it is not limited to a gear. As the gear member, for example, a member that transmits rotational force, such as a gear, a toothed belt, and a transmission belt, can be used as appropriate.

  Further, according to each embodiment, the motor M continues to rotate in the stopped state. Thereby, the control of the motor can be simplified.

  Further, according to each embodiment, the rotational force from the motor M not only rotates the rotary 105 but also the rotational force is transmitted to the rotational force transmitted member to rotate the rotational force transmitted member. Here, the rotational force receiving member includes at least a conveyance roller (registration roller) 53 that conveys the sheet S, a fixing device 54 that fixes the developer image transferred to the sheet S, and a photosensitive member. In order to transfer the developer image formed on the drum 2 to the sheet S, it is any one of the transfer belts 7 that convey the sheet S to the photosensitive drum 2.

  In the above-described embodiment, the printer is exemplified as the electrophotographic image forming apparatus. However, the present invention is not limited to this. For example, it may be another electrophotographic image forming apparatus such as a copying machine or a facsimile machine, or another electrophotographic image forming apparatus such as a multifunction machine combining these functions. In addition, an intermediate transfer member (belt) is used, and developer images of respective colors are sequentially superimposed and transferred onto the intermediate transfer member. An example of an image forming apparatus that collectively transfers a developer image carried on the intermediate transfer member onto a recording medium is illustrated. However, the present invention is not limited to this. For example, an electrophotographic image forming apparatus may be used in which a recording medium carrier is used and developer images of respective colors are sequentially superimposed and transferred onto the recording medium carried on the recording medium carrier. The same effect can be obtained by applying the present invention to the image forming apparatus.

Sectional drawing which shows the structure of the laser beam printer which is an example of an electrophotographic image forming apparatus The front view which shows the structure of the drive transmission mechanism which concerns on 1st Embodiment. The right view of the drive transmission mechanism which concerns on 1st Embodiment Front view showing another example of the drive transmission mechanism according to the first embodiment The front view which shows the structure of the drive transmission mechanism which concerns on 2nd Embodiment. A right side view of a drive transmission mechanism according to the second embodiment The front view which shows the structure of the drive transmission mechanism which concerns on 3rd Embodiment. The right side view of the drive transmission mechanism concerning a 3rd embodiment

Explanation of symbols

S: Sheet (recording medium)
2 ... Photosensitive drums 18a to 18d ... Developing device 101 ... Trigger cams 101a, 121a to 121d ... Claw parts (engaging parts)
102 ... Solenoid 103 ... Trigger spring (elastic member)
104, 127 ... Rotary drive gear 105 ... Rotary 105a, 126 ... Rotary gear 106 ... Missing gear 106a, 126a ... Gear 106b, 126b ... Missing tooth 182a to 182d ... Developing roller

Claims (7)

In a color electrophotographic image forming apparatus for forming an image on a recording medium,
An electrophotographic photoreceptor;
A rotatable rotating support for supporting a plurality of developing devices for developing an electrostatic latent image formed on the electrophotographic photosensitive member;
A rotating support gear member that rotates integrally with the rotating support;
A first transmission gear member engaged with the rotary support gear member;
A rotating member that rotates integrally with the first transmission gear member;
An engagement member that detachably engages with an engagement portion provided on the rotation member in order to stop the rotation of the rotation member;
A second transmission gear member for receiving the rotational force from the motor and transmitting the rotational force of the drive member that rotates in one direction to the rotational member;
Have
A stop state in which the second transmission gear member stops receiving the rotational force from the driving member by the engagement of the engaging member with the engaging portion and the rotation of the rotating member being stopped. And an operating state in which the second transmission gear member rotates by receiving the transmission of the rotational force from the drive member by rotating the rotating member, and in the operating state, Rotating, sequentially moving the developing device to a developing position for developing the electrostatic latent image ,
The driving member is rotated by receiving a rotational force from a motor, and the rotational force is transmitted to the rotational support via the second transmission gear member and the rotational support gear member to rotate the rotational support. In addition, the rotational force from the motor is transmitted to the rotational force transmitted member to rotate the rotational force transmitted member,
The rotational force receiving member includes at least one of a conveyance roller for conveying the recording medium, a fixing device for fixing the developer image transferred to the recording medium to the recording medium, and the electrophotographic photosensitive member. A color electrophotographic image forming apparatus characterized in that it is one . The second transmission gear member is a sliding gear,
A fixed portion engaged with the sliding gear; and a sliding portion that is engaged with the rotating member and rotates in synchronization with the fixed portion. A predetermined torque or more is provided between the fixed portion and the sliding portion. A torque transmitting means that, when generated, the fixed portion and the sliding portion slide and do not rotate synchronously;
When the electric actuator is disengaged from the engaging portion, the fixed portion and the sliding portion rotate synchronously, and the rotational force of the sliding gear is transmitted to the rotating member, so that the rotating member Rotated,
When the electric actuator is engaged with the engaging portion, the fixed portion and the sliding portion slide, the rotational force of the sliding gear is cut off from the rotating member, and the rotation of the rotating member is stopped. The color electrophotographic image forming apparatus according to claim 1 . In a color electrophotographic image forming apparatus for forming an image on a recording medium,
An electrophotographic photoreceptor;
A rotatable rotating support for supporting a plurality of developing devices for developing an electrostatic latent image formed on the electrophotographic photosensitive member;
A rotating support gear member that rotates integrally with the rotating support;
A first transmission gear member engaged with the rotary support gear member;
A rotating member that rotates integrally with the first transmission gear member;
An engagement member that detachably engages with an engagement portion provided on the rotation member in order to stop the rotation of the rotation member;
A second transmission gear member for receiving the rotational force from the motor and transmitting the rotational force of the drive member that rotates in one direction to the rotational member;
Have
A stop state in which the second transmission gear member stops receiving the rotational force from the driving member by the engagement of the engaging member with the engaging portion and the rotation of the rotating member being stopped. And an operating state in which the second transmission gear member rotates by receiving the transmission of the rotational force from the drive member by rotating the rotating member, and in the operating state, Rotating, sequentially moving the developing device to a developing position for developing the electrostatic latent image ,
The second transmission gear member is a toothless gear, the driving member is a gear, the engagement member is an electric actuator, the gearless gear is a gear portion that can mesh with a gear that is the driving member, and the electric actuator is M gear teeth that face the gear as the driving member while being engaged with the engaging portion of the rotating member, and urge the rotating member in the rotation direction. And the disengagement of the electric actuator with respect to the engaging portion is released, so that the gear portion of the toothless gear meshes with the gear as the driving member by the elastic force of the elastic member. The rotating member is rotated so that the rotational force of the gear as the driving member rotates the rotating support through the gear portion, the rotating support gear member, and the first transmission gear member. Let the electric act When the eta is engaged with the engaging portion, the rotation of the rotating member is stopped at a position where the missing tooth portion of the missing tooth gear faces the gear that is the driving member. A color electrophotographic image forming apparatus, wherein the rotational force of the gear is not transmitted to the second transmission gear member . The driving member is rotated by receiving a rotational force from a motor, and the rotational force is transmitted to the rotational support via the second transmission gear member and the rotational support gear member to rotate the rotational support. In addition, the rotational force from the motor is transmitted to the rotational force transmitted member to rotate the rotational force transmitted member,
The rotational force receiving member includes at least one of a conveyance roller for conveying the recording medium, a fixing device for fixing the developer image transferred to the recording medium to the recording medium, and the electrophotographic photosensitive member. color electrophotographic image forming apparatus according to claim 3, characterized in that one or. In a color electrophotographic image forming apparatus for forming an image on a recording medium,
An electrophotographic photoreceptor;
A rotatable rotating support for supporting V (V is a natural number) developing devices for developing an electrostatic latent image formed on the electrophotographic photosensitive member;
An electric actuator;
A rotating member having M (M is a natural number) engaging portions engageable with the electric actuator;
A transmission gear having the number of teeth X (X is a natural number) to which a rotational force from a driving member rotating in one direction is transmitted, and a tooth that meshes with the transmission gear and rotates integrally with the rotation support body. Drive support gear set such that the value of each natural number satisfies a relationship in which (X / M) is a divisor of (Y / V) Mechanism,
Have
The rotation member rotates 1 / M each time the electric actuator is disengaged from the engagement portion, and the rotation support is supported by a transmission gear that rotates integrally with the rotation member each time the 1 / M rotation is performed. A developing position for developing the electrostatic latent image by transmitting rotational force to the body gear, rotating the rotating support body by an angle W that is a divisor of (360 / V), and then stopping the rotating support body. in order to move to,
The drive transmission mechanism is
A toothless gear having a gear portion engageable with the driving member, and M number of toothless portions facing the driving member when the electric actuator is engaged with an engaging portion of the rotating member; ,
An elastic member biasing the rotating member in the rotation direction,
When the engagement of the electric actuator with respect to the engagement portion is released, the rotating member is rotated so that the gear portion of the toothless gear meshes with the drive member by the elastic force of the elastic member,
The electrophotographic actuator is engaged with the engagement portion, whereby the rotation of the rotating member is stopped at a position where the tooth missing portion of the tooth missing gear faces the drive member. Image forming apparatus. In a color electrophotographic image forming apparatus for forming an image on a recording medium,
An electrophotographic photoreceptor;
A rotatable rotating support for supporting V (V is a natural number) developing devices for developing an electrostatic latent image formed on the electrophotographic photosensitive member;
An electric actuator;
A rotating member having V engaging portions engageable with the electric actuator, and rotating integrally with the rotating support;
A gear portion that can mesh with a driving member rotating in one direction, and V number of toothless portions facing the driving member in a state where the electric actuator is engaged with the engaging portion. A rotation support gear that rotates integrally with the rotation support, and a drive transmission mechanism in which the engagement portion and the missing tooth portion are set to positions corresponding to the development position;
Have
The electric actuator is disengaged from the engaging portion, and a gear portion of a rotating support gear that rotates in synchronism with the rotating member every time the electric actuator is engaged is engaged with the driving member to disengage the rotating support member. A color electrophotographic image forming apparatus, which is rotated by an angle W of (360 / V) and stopped. The drive transmission mechanism is
A guide member having V guide portions that rotate in synchronization with the rotation member;
A lever member engaged with a guide portion of the guide member;
An urging member that urges the lever member to urge the rotating member in the rotation direction;
When the electric actuator is disengaged from the engaging portion, the lever member urges the guide member in the rotation direction by the urging force of the urging member, and the gear portion of the rotation support gear. The rotating member is rotated so as to mesh with the drive member,
By the electrical actuator is engaged with the engaging portion, the claims rotation of the rotary member at a position where the toothless portion of the rotary support gear is opposed to said drive member, characterized in that it is stopped 6. A color electrophotographic image forming apparatus according to 6.

Images