JP2008310304A - Color electrophotographic image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a color electrophotographic image forming apparatus which achieves a simplified configuration in which a rotary is rotated to change over each developing device to a development position to thereby enable the costs and the space of the color electrophotographic image forming apparatus to be reduced, and which achieves simplified changeover operation resulting in reduction in an operating time. <P>SOLUTION: The image forming apparatus sequentially moves and changes over the respective developing devices 18a to 18d supported by the rotary 102 to the development position which faces a photosensitive drum 2 by the rotation of the rotary 102. The rotary 102 is rotated to move the developing devices 18a to 18d. A cam 101 is rotated integrally with the rotary 102, and thereby abutment portions 101e to 101h of the cam 101 are abutted against a regulating rotatable member 105, so that the developing devices 18a to 18d are spaced from the photosensitive drum 2. In a state in which the developing devices 18a to 18d are abutted against the photosensitive drum 2, the cam 101 is spaced from the regulating rotatable member 105 by recesses 101a to 101d of the cam 101. <P>COPYRIGHT: (C)2009,JPO&INPIT

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).

  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, the rotation support is rotated. As a result, the plurality of developing devices supported by the rotating support are sequentially moved to the developing position facing the photosensitive drum. Further, the rotary support is provided so as to be swingable with respect to the apparatus main body. As a result, the developing device is in contact with or separated from the photosensitive drum (see Patent Document 1).

  Specifically, the rotation support (rotation body) is rotatably supported by a swinging body that is swingable with respect to the apparatus main body. The rotary support rotates in response to the driving force from the motor. As a result, the developing device (developing unit) sequentially moves to the developing position. The swinging body is rotatably provided with a cam that rotates upon receiving a driving force. The cam rotates and engages with an engaging portion provided in the apparatus main body. As a result, the oscillating body oscillates and the developing device is separated from the photosensitive drum.

JP 2005-148319 A

  Thus, the conventional configuration requires a cam and a drive transmission mechanism for rotating the cam in order to swing the swinging body. Therefore, a space for mounting them inside the apparatus is required. For this reason, it may be a factor that hinders downsizing of the image forming apparatus.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a color electrophotographic image forming apparatus that simplifies the configuration in which the developing device is positioned at the developing position.

  Another object of the present invention is to provide a color electrophotographic image forming apparatus in which the construction for retracting the developing device from the developing position is simplified.

  Another object of the present invention is to move the developing device in a state in which the developing device is moved away from the developing position in a crossing direction intersecting the rotating direction of the rotating support when the developing device is moved by rotation of the rotating support. It is an object of the present invention to provide a color electrophotographic image forming apparatus that can be moved.

  Another object of the present invention is to move the developing device to be supported to the developing position from the rotation direction of the rotary support, and to move the developing device to be supported from the crossing direction intersecting the rotation direction to the developing position. It is an object of the present invention to provide a color electrophotographic image forming apparatus that can be used.

  Another object of the present invention is to provide a color electrophotographic image forming apparatus in which the size of the image forming apparatus is reduced by simplifying the configuration in which the developing apparatus is positioned at the developing position.

  Another object of the present invention is to shorten the operation time required to replace the developing device located at the developing position by simplifying the configuration in which each developing device is sequentially positioned to the developing position. A color electrophotographic image forming apparatus is provided.

  Another object of the present invention is to provide a color electrophotographic image forming apparatus having a simplified structure in which each developing device is moved to a developing position by rotating a rotary support.

  Another object of the present invention is to realize a low cost, space saving, and position at the developing position by simplifying the configuration in which each developing device is moved to the developing position by rotating the rotary support. Another object of the present invention is to provide a color electrophotographic image forming apparatus in which the operation time required for replacing the developing device is shortened.

  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, and an electrophotographic photosensitive drum and an electrostatic formed on the electrophotographic photosensitive drum. Rotating support for supporting a plurality of developing devices for developing a latent image, and rotating to sequentially move the supporting developing device from a rotating direction to a developing position for developing the electrostatic latent image by rotating. A supporting member, a motor, a swinging member that supports the rotating support member so as to swing, and a rotating member that rotates integrally with the rotating support member that rotates by receiving a rotational force from the motor, A separation unit for moving the developing device supported by the rotating support to the developing position from an intersecting direction intersecting the rotation direction of the rotating support, and a retracted position for retracting the developing device from the developing position. A rotating member having a contact portion for moving from the intersecting direction; and a separation member that rotates in accordance with the rotation of the rotating member to move the developing device from the intersecting direction to the developing position. In order to move the developing device from the intersecting direction to the retracted position, and in contact with the contact portion that rotates according to the rotation of the rotating member, A regulating member that regulates swinging of the rotary support in a state where it is in contact with the contact portion, and in a state where the regulating member is separated from the separation portion, the developing device is positioned at the development position. The rotating support may swing so that the developing device is positioned at the retracted position when the regulating member is in contact with the contact portion.

  According to the present invention, the configuration for positioning the developing device to the developing position can be simplified.

  According to the present invention, when the developing device is moved by the rotation of the rotating support, the developing device is moved in a state in which the developing device is moved away from the developing position in a crossing direction that intersects the rotating direction of the rotating support. It is an object of the present invention to provide a color electrophotographic image forming apparatus that achieves this.

  According to the present invention, the developing device to be supported is moved to the developing position from the rotation direction of the rotating support, and the developing device to be supported is moved from the intersecting direction intersecting the rotation direction to the developing position. did it. As a result, according to the present invention, the developing device supported by the rotating support can be rotated and moved further away from the electrophotographic photosensitive drum in a direction intersecting the rotating direction.

  In addition, according to the present invention, the size of the image forming apparatus can be reduced by simplifying the configuration in which the developing device is positioned at the developing position.

  In addition, according to the present invention, it is possible to shorten the operation time required to replace the developing device located at the developing position by simplifying the configuration in which the developing device is sequentially positioned to the developing position.

  In addition, according to the present invention, it is possible to simplify the configuration in which each developing device is moved to the developing position by rotating the rotary support.

  In addition, according to the present invention, by simplifying the configuration in which the rotating support is rotated to move each developing device to the developing position, development that is inexpensive, saves space, and is located at the developing position is possible. The operating time required to replace the device could be shortened.

  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 has an electrophotographic photosensitive drum 2. Around the photosensitive drum 2, a charging roller 3, an exposure device 4, four developing devices 18a to 18d, and a cleaning device 6 are arranged. The charging roller 3 is a charging unit for uniformly charging the photosensitive drum 2. The exposure device 4 is an exposure unit that irradiates the photosensitive drum 2 with laser light corresponding to image information. An electrostatic latent image is formed on the photosensitive drum 2 by irradiating the charged photosensitive drum 2 with the laser light. 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.

  The developing device 18a contains a yellow developer, and develops the electrostatic latent image with the yellow developer. The developing device 18b contains a magenta developer, and develops the electrostatic latent image with the magenta developer. The developing device 18c contains a cyan developer, and develops the electrostatic latent image with the cyan developer. The developing device 18d contains a black developer, and develops the electrostatic latent image with the black developer. That is, the developing devices 18a to 18d develop the electrostatic latent image formed on the photosensitive drum 2.

  The cleaning device 6 is a cleaning unit that removes the developer remaining on the surface of 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 7. Then, the surface of the photosensitive drum 2 is uniformly charged by the charging roller 3. At the same time, a yellow image is irradiated by the exposure device 4 to form a yellow electrostatic latent image on the photosensitive drum 2.

  Simultaneously with the formation of the electrostatic latent image, the yellow developing device is supported by supporting the four developing devices 18a to 18d and rotating a rotatable rotary (rotating support) 102 by a drive transmission mechanism (described later). 18a is positioned at the developing position 18X facing the photosensitive drum 2. At the developing position 18X, the developing roller 182a included in the developing device 18a is in contact with the photosensitive drum 2. 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 electrostatic latent image on the photosensitive drum 2. Thereby, the electrostatic latent image is developed with a yellow developer. That is, the rotary 102 supports and rotates a plurality of developing devices 18a to 18d, thereby sequentially moving the supporting developing devices one by one to the developing position 18X facing the photosensitive drum 2. The developing device located at the developing position develops the electrostatic latent image according to the color of the developer stored therein. Here, in this embodiment, as the developing rollers 182a to 182d, elastic rollers in which rubber is coated around a metal shaft 182m (FIGS. 3 and 5) are used. In the present embodiment, the developing rollers 182a to 182b are in contact with the photosensitive drum 2 at the developing position 18X (contact developing method). Each of the developing rollers 182a to 182d develops the electrostatic latent image while being in contact with the photosensitive drum 2. However, the present invention is not limited to this configuration. The present invention can also be applied to a configuration in which the latent image is developed in the developing position 18X in a close state without being in contact with each other. Even with such a configuration, the effects described below can be obtained.

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

  As described above, the primary transfer of the yellow developer image is completed. The developing devices (18b to 18d) for magenta, cyan, and black are sequentially rotated by the rotation of the rotary 102 and positioned at the developing position 18X that faces the photosensitive drum 2. Then, as in the case of yellow, electrostatic latent image formation, development, and primary transfer are sequentially performed for magenta, cyan, and black. As a result, the four color developer images are superimposed on the 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 residual toner on the transfer belt 7 is not in contact with the transfer belt 7.

  On the other hand, the sheet S as a recording medium is stored in a cassette 51 provided at the lower part of the apparatus. The recording medium is for forming a developer image, and is, for example, a recording paper, an OHP sheet, or the like. The sheets S are separated and fed one by one from the cassette 51 by the feeding roller 52 and fed to the registration roller pair (conveying roller) 53. The roller pair 53 sends out the fed sheet S between the transfer belt 7 and the transfer roller 82. Here, the transfer roller 82 and the transfer belt 7 are in pressure contact (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, and the four color developer images superimposed on the transfer belt 7 are collectively transferred onto the surface of the conveyed sheet S ( Secondary transfer).

  The sheet S on which the developer image is transferred is sent to the fixing device 54. In the fixing device 54, the sheet S is heated and pressurized, and 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 is discharged from the fixing device 54 to the discharge portion of the upper cover 55 outside the apparatus.

  Here, a drive transmission mechanism for rotating the rotary (rotary support) 102 will be described with reference to FIGS. 2 and 3. FIG. 2 is a front view showing the configuration of the drive transmission mechanism. FIG. 2 illustrates a state in which the developing roller 182a of the developing device 18a is located at the developing position 18X facing the photosensitive drum 2. FIG. 3 is a right side view of FIG. 2 viewed from the right direction. However, FIG. 2 does not show the main body frame 171 shown in FIG. In FIG. 3, 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 102 so that the four developing devices 18a to 18d supported by the rotary 102 are sequentially switched to the developing positions facing the photosensitive drum 2. Let Hereinafter, the configuration of the drive transmission mechanism will be described.

  The drive gear 172 is rotatably supported (provided) on a shaft 107 that is rotatably supported with respect to the image forming apparatus main body A. The gear 172 receives a rotational force from the motor M (drive source) (FIG. 2) and rotates.

  Note that the rotational force transmission mechanism M1 that transmits rotational force from the motor M to the gear 172 can be appropriately used as long as it is a gear train, a toothed belt, and the like and can transmit rotational force. Moreover, the rotational force transmission mechanism M1 cancels the meshing state of the gears constituting the gear train using, for example, a solenoid. Thereby, even if the motor M is rotating, the gear 172 may not be transmitted with the rotational force.

  The arm 103 is a swinging member supported (provided) so as to be swingable with respect to the apparatus main body A. That is, one end side of the arm 103 is rotatably provided on the shaft 107 provided on the main body frame 171. The other end side of the arm 103 is an arm spring (for example, a compression spring) (elastic member) 104 having one end fixed to the apparatus main body A at the other end side end of the arm 103 that rotatably supports the rotary 102. The other end is attached. As a result, the arm 103 receives an urging force (elastic force, rotational force) in the direction of arrow A (FIG. 2) at the center of the shaft 107 by the elastic force of the arm spring 104.

  The rotary 102 supports a plurality (four in this case) of developing devices 18 a to 18 d and is rotatably supported by the arm 103. That is, the developing device is attached to the rotary 102. Here, the developing devices 18a to 18d may be fixed to the rotary 102 or detachable. The developing device of this embodiment is a developing cartridge that is detachably mounted on the rotary 102 by a user. That is, it is detachable from the rotary 102. Thus, according to the present embodiment, the developing device can be replaced by the user. Therefore, maintenance of the apparatus main body A is easy. The rotary 102 is provided with a gear portion (rotating support gear) 102 a along the rotation direction of the rotary 102. The gear portion 102 a meshes with the drive gear 172. That is, when the drive gear 172 rotates in the direction of arrow A (FIG. 2), the rotary 102 rotates in the direction of arrow B (FIG. 2). When the gear 172 stops rotating, the rotary 102 also stops rotating. As described above, according to the present embodiment, the gear 172 can stop rotating even when the motor M continues to rotate. This is because when the rotational force is transmitted from the motor M to the gear 172 via the mechanism M1, for example, a part of the mechanism M1 is disconnected by the action of a solenoid (not shown).

  The regulation roller 105 is rotatably supported by a roller holder 106 installed in the apparatus main body A. The regulating roller 105 is a regulating member that regulates the swing of the rotary 102. Further, if the surface layer of the regulation roller 105 is a rubber layer having elasticity, it is possible to reduce the noise and reliably rotate with a high friction coefficient. Furthermore, here, the regulation roller 105 is rotatably supported by the roller holder 106. However, if the slidability of the outer peripheral surface of the regulation roller 105 is good, it does not need to be rotatable. There is no need for a roller. According to this embodiment, the roller 105 is an elastic roller. Since it is an elastic roller, according to this embodiment, the rotary 102 can be rotated with high accuracy. Further, noise during rotation of the rotary 102 can be reduced. The elastic roller includes even if only the surface layer is elastic (for example, rubber) or the entire roller is elastic.

  The roller 105 is an elastic roller rotatably supported on a shaft 106a (FIGS. 2, 3, and 4) fixed to the apparatus main body A. A shaft 106 a that supports the roller 105 is disposed so as to be parallel to the rotation axis of the rotary 102. When the rotary 102 rotates, the roller 105 comes into contact with contact portions 101e to 101h of a cam 101, which will be described later, and rotates.

  The cam (rotating member) 101 is a rotating member (guide member) that rotates integrally with a rotary (rotating support) 102. In the present embodiment, the cam 101 is separate from the rotary 102 and is attached to the rotary 102. However, the cam 101 and the rotary 102 always move in synchronization. Therefore, both may be formed integrally. The cam 101 includes contact portions 101e to 101h that come into contact with the rollers 105 and separation portions (contact release portions) 101a to 101d that do not come into contact with the rollers 105. The separation portions 101 a to 101 d are concave portions having substantially the same shape as the outer shape of the roller 105. The contact portions 101e to 101h and the separation portions (concave portions) 101a to 101d are alternately arranged along the outer peripheral surface of the cam 101 at substantially equal angles from the rotation center 101i of the cam 101. The cam 101 is located at one end in the longitudinal direction of the developing devices 18 a to 18 d supported by the rotary 102 and is provided integrally with the rotary 102.

  Further, the separating portions 101a to 101d are recessed portions provided to be recessed at a plurality of locations along the rotation direction B of the cam 101 (FIG. 2). In the rotation direction B, the recess has an inclined surface 101m that rises from the downstream side to the upstream side on the upstream side. By having the inclined surface 101 m (FIG. 2), the developing devices 18 a to 18 d can move away smoothly from the developing position 18 </ b> X in a direction crossing the rotation direction in accordance with the rotation of the rotary 102. That is, when the contact portions 101e to 101h come into contact with the roller 105 in accordance with the rotation of the rotary 102, the developing devices 18a to 18d are moved from the crossing direction to the retreat position where the development devices 18a to 18d are retreated. The retracted position is a position where the developing devices 18a to 18d (developing rollers 182a to 182d) move away from the developing position 18X in the intersecting direction.

  Similarly, the concave portion has a slope 101n (FIG. 2) that descends from the downstream side to the upstream side in the rotation direction B on the downstream side. By having the inclined surface 101n, the developing devices 18a to 18d can approach smoothly toward the developing position 18X in the direction intersecting the rotational direction according to the rotation of the rotary 102. In other words, the developing units 18a to 18d are moved from the retracted position to the developing position 18X from the crossing direction by reaching the position where the separating portions 101a to 101d face the roller 105 according to the rotation of the rotary 102.

  However, the slope 101n may not be provided. For example, it may be a right angle instead of a slope. The inclination angles of the slope 101m and the slope 101n can be selected as appropriate.

  For example, as shown in FIG. 5, the cam 101 rotates integrally with the rotary 102. Then, when the contact portion 101 e comes into contact with the regulating roller (regulating member) 105, the developing roller 182 a included in the developing device 18 a is separated from the photosensitive drum 2. Even if the other contact portions 101f to 101h come into contact with the regulation roller 105, the developing rollers 182b to 182d of the developing devices 18b to 18d are separated from the photosensitive drum 2, respectively. Therefore, the roller (regulating member) 105 is opposed to the separating portions 101a to 101d that rotate according to the rotation of the cam 101 in order to move the developing devices 18b to 18d from the intersecting direction to the developing position 18X. It is provided in the position to do. Further, the roller 105 is provided at a position in contact with the contact portions 101e to 101h that rotate according to the rotation of the cam 101 in order to move the developing devices 18b to 18d from the intersecting direction to the retracted position. The roller 105 regulates the swing of the rotary 102 in a state where the roller 105 is in contact with the contact portions 101e to 101h.

  That is, the rotary 102 swings so that the developing devices 18b to 18d are located at the developing position when the roller 105 is separated from the separating portions 101a to 101d. Further, the rotary 102 swings so that the developing devices 18b to 18d are located at the retracted position when the roller 105 is in contact with the contact portions 101e to 101h. Each structure mentioned above is the same also in embodiment mentioned below.

  Here, as shown in FIG. 3, a cam (rotating member) 101, a rotary (rotating support) 102, an arm (swinging member) 103, and a regulating roller (regulating member) 105 are supported by the developing device to be supported. It arrange | positions at the one end side and other end side of a longitudinal direction.

  The state shown in FIG. 5 shows a state where the rotary 102 is rotating as will be described later. However, the state shown in FIG. 5 is also a state where the rotary 102 stops rotating and the rotary 102 is positioned at the standby position 18Y. Here, the standby position 18Y is a state in which the rotary 102 is stopped and each of the developing devices does not perform development. As shown in FIG. 5, in this state, each developing roller is not in contact with the photosensitive drum 2. For example, the developing roller 182a is located at the standby position 18Y on the downstream side of the roller 105. Further, at the standby position 18Y, the roller 105 supports the lower side of the rotary 102 disposed on the one end side. A roller 105 supports the lower part of the rotary 102 disposed on the other end side. Thus, the rotary 102 supporting each developing device is restricted from swinging by the rollers 105.

  On the other hand, as shown in FIG. 2, when the developing roller 182a is in contact with the photosensitive drum 2, the roller 105 is opposed to the bottom surface of the concave portion (separating portion) 101a. This state is a state where the developing device is located at the developing position 18X. When the developing roller 182b is located at the developing position 18X in contact with the photosensitive drum 2, the roller 105 is opposed to the bottom surface of the recess 101b. Similarly, when the developing roller 182c is positioned at the developing position 18X in contact with the photosensitive drum 2, the roller 105 is opposed to the bottom surface of the recess 101c. In the state where the developing roller 182d is located at the developing position in contact with the photosensitive drum 2, the roller 105 is opposed to the bottom surface of the recess 101d. That is, the cam 101 is separated from the regulation roller 105.

  2 and 3 showing the developing device during development, the roller 105 is in the vicinity of the recess 101a (101d), and the recess 101a (101d) is arranged so that the roller 105 and the cam 101 do not contact each other. Has been. Therefore, the arm 103 biased by the elastic force of the spring 104 biases the rotary 102. The urging force (elastic force) becomes a contact pressure between the developing roller 182a (˜182d) and the photosensitive drum 2.

  The drive gear 172 receives the rotational force from the motor M and rotates in the arrow A direction (FIG. 2). Then, as described above, the rotary 102 rotates in the arrow B direction (FIG. 2). The cam 101 provided in the rotary 102 also rotates in the direction of arrow B together with the rotary 102. FIG. 4 shows a state where the rotary 102 is rotated by receiving the rotational force of the drive gear 172. FIG. 4 illustrates a state in which the development of the developing device 18a is completed, the developing device 18a is retracted from the developing position 18X, and the developing device 18b is directed to the developing position 18X.

  In this embodiment, the arm (swinging member) 103 is rotatably supported by the main body A of the image forming apparatus. The arm 103 supports a rotation center 101 i of a rotary (rotary support) 102. The rotation center 101 i is also the rotation center of the cam (rotating member) 101. The cam 101 is attached to the rotary 102. Therefore, the arm 103 supports the rotation center 101 i of the cam 101.

  The rotary 102 has a gear portion (rotating support gear) 102a provided on the entire circumference along the rotation direction. A drive gear (oscillating member gear) 172 is provided on the same axis as the rotation center 103a that rotatably supports the arm 103 on the apparatus main body A. Thereby, the gear 172 and the gear part 102a are meshed. Therefore, even if the arm 103 swings, the gear 172 and the gear portion 102a can always maintain the meshing state. The same applies to the following embodiments.

  The rotation center 103a is the axis of the shaft 172a that rotatably supports the gear 172. The shaft 172a is fixed to the main body frame 171. One end of the arm 103 is rotatably attached to the shaft 172a.

  As described above, as shown in FIGS. 2 and 3, the elastic force (biasing force) of the spring 104 acts as a force with which the developing roller 182 a presses against the photosensitive drum 2. From this state, when the rotary 102 rotates, the pressure contact state between the developing roller 182a and the photosensitive drum 2 is released. When the pressure contact state is released, the urging force of the spring 104 acts as a force that the cam 101 presses against the roller 105. As a result, the cam 101 can reliably contact the roller 105.

  As described above, the outer peripheral surface of the cam 101 excluding the places where the separation portions (recess portions) 101a to 101d are provided are the contact portions 101e to 101h with which the rollers 105 come into contact. When the contact portions 101e to 101h are in contact with the roller 105, the developing devices 18a to 18d are configured not to contact the photosensitive drum 2. Therefore, the developing devices 18a to 18d can be sequentially moved to the developing position without affecting the photosensitive drum 2. The contact portions 101e to 101h and the separation portions 101a to 101d are alternately arranged along the rotation direction of the cam 101 (rotary 102). The distance L1 between the separation portions 101a to 101d and the rotation center 101i of the cam 101 is shorter than the distance L2 between the contact portions 101e to 101h and the rotation center 101i of the cam 101 (FIG. 5).

  When the developing device 18b (to 18d) is moved to the developing position 18X, a controller (not shown) cuts off the rotational force of the drive gear 172, and the rotary 102 stops rotating. Then, the developing device 18b reaches the developing position 18X. At the developing position 18X, the developing roller 182b (˜182d) and the photosensitive drum 2 are in pressure contact. In this state, as shown in FIG. 2, the roller 105 faces the separated portion (recessed portion) 101 b (−101 d) of the cam 101 in a separated state. The separation part 101b (-101d) and the roller 105 are in a separated state. The developing devices 18a to 18d sequentially move to the developing position 18X while repeating such an operation. In the present embodiment, the gap G (FIG. 2) between the roller 105 and the bottom surface of the recess 101b as the separation portion is about 1.5 mm apart.

  Thus, in the present embodiment, the cam 101 having the contact portions 101e to 101h and the separation portions 101a to 101d is integrally provided on the rotary 102, and the roller 105 is provided on the apparatus main body A. Accordingly, the developing devices 18a to 18d (developing rollers 182a to 182d) can be brought into contact with or separated from the photosensitive drum 2 while rotating the developing devices 18a to 18d only by rotating the rotary 102. For this reason, the structure which rotates the rotary 102 and moves each developing device 18a-18d to the developing position 18X can be simplified. Therefore, the cost of the apparatus can be reduced. Moreover, the apparatus can be miniaturized. Further, the developing devices 18a to 18d (developing rollers 182a to 182d) are brought into contact with or separated from the photosensitive drum 2 while being rotated. Therefore, the switching operation is simplified and the operation time can be shortened as compared with the conventional operation.

  Here, a modification of the cam 101 is shown in FIG.

  FIG. 6 is an enlarged view of a main part showing a state around the separation part (concave part) of the cam 101. FIG. 6A is a view showing a state before the developing roller 182a contacts the photosensitive drum 2 (before reaching the developing position 18X). FIG. 6B is a diagram illustrating a state in which the developing roller 182a is in contact with the photosensitive drum 2 (when the developing roller 182a reaches the developing position 18X).

  The cam 101 shown in FIG. 6 further includes a contact assisting portion 101k in addition to the contact portion and the separation portion described above. As shown in FIG. 6 (A), the contact assisting portion 101k is configured so that the developing roller 182a before contacting the photosensitive drum 2 is maintained at the same position as that contacting the photosensitive drum 2. 105 is contacted. Here, only the peripheral portion of the developing roller 182a is illustrated, but the other peripheral portions of the developing roller are similarly configured.

  That is, in the present embodiment, the contact assisting portion 101k is provided in the separation portions 101a to 101d. The auxiliary portion 101k is disposed on the downstream side in the rotation direction B of the separation portions 101a to 101d. Therefore, the auxiliary portion 101k comes into contact with the roller 105 before the developing rollers 182a to 182d come into contact with the photosensitive drum 2. Therefore, the developing rollers 182a to 182d before coming into contact with the photosensitive drum 2 can be positioned on substantially the same rotation locus as the position in contact with the photosensitive drum 2.

  With this configuration, as shown in FIG. 6B, the developing roller 182a contacts the photosensitive drum 2 at substantially the same position as that of the photosensitive drum 2. That is, the developing roller 182a enters the photosensitive drum with substantially the same rotation locus as that in contact with the photosensitive drum 2. Therefore, it is possible to reduce an impact when the developing roller 182a and the photosensitive drum 2 come into contact with each other. Therefore, according to this embodiment, it is effective in improving image quality, reducing wear of the developing roller 182a or the photosensitive drum 2, and reducing noise. However, the present invention is not limited to this. The present invention is applicable even when the auxiliary unit 101k is not provided.

  The rotary 102, the arm 103, the cam 101, and the elastic roller 105 are arranged on one end side and the other end side in the longitudinal direction of the developing devices 18a to 18d supported by the rotary 102. When the developing devices 18a to 18d are positioned at the standby position 18Y where development is not performed, the rotary 102 disposed on the one end side is supported below the roller 105 disposed on the one end side. (FIG. 5). Further, the rotary 102 arranged on the other end side is supported below the roller 105 arranged on the other end side. As a result, the swing of the rotary 102 is restricted by the roller 105. When the rotary 102 is located at the developing position 18X, the rotary 102 disposed on the one end side and the other end side swings when the developing rollers 182a to 182d come into contact with the photosensitive drum 2. Is regulated.

  As described above, various contact methods and contact release (separation) methods can be adopted by changing the shape of the cam 101 in various ways.

[Second Embodiment]
Next, another form of the drive transmission mechanism for rotating the rotary 102 will be described with reference to FIGS.

  FIG. 7 is a front view showing the configuration of the drive transmission mechanism, and shows a state in which the developing roller 182a is at the developing position facing the photosensitive drum 2. FIG. FIG. 8 is a right side view of FIG. 7 viewed from the right direction. However, in FIG. 7, the main body frame 171 shown in FIG. 8 is not shown. In FIG. 8, the transfer belt 7 and the transfer roller 81 shown in FIG. 7 are not shown.

  In the present embodiment, cams 183 as rotating members (guide members) that rotate integrally with the rotary 102 are provided in the developing devices 18 a to 18 d supported by the rotary 102. Other configurations and operations are the same as those in the above-described embodiment.

  As shown in FIGS. 7 and 8, each of the developing devices 18 a to 18 d includes contact portions 183 e to 183 h that come into contact with the regulation roller 105 and separation portions (recesses and contact release portions) that release the regulation from the regulation roller 105. 183a to 183d. The contact portion and the separation portion are provided on the outer surface of the outer frame 18S of the developing device. The contact part and the separation part have the same configuration (shape) as in the above-described embodiment. Further, the separation portions (recess portions) 183a to 183d do not contact the roller 105 during development (when the developing roller and the photosensitive drum are in contact), similarly to the separation portion of the cam 101 of the above-described embodiment. The urging force (elastic force) of the arm spring (elastic member) 104 acts as a force for the developing roller 182a to come into pressure contact with the photosensitive drum 2. On the other hand, when the rotary 102 is rotated by the rotational force of the drive gear 172 to move the next developing device to the developing position 18X, the separating portions 183a to 183d are brought into pressure contact with the roller 105. As a result, the developing rollers 182a to 182d are separated from the photosensitive drum 2.

  As described above, in this embodiment, the developing devices 18a to 18d are provided with the cams 183 having the contact portions 183e to 183h and the separation portions (recess portions) 183a to 183d. Thereby, the cam 101 shown in the embodiment described above can be eliminated. As a result, the apparatus can be further reduced in size.

  Also in this embodiment, a contact assisting portion (FIGS. 6A and 6B) may be provided in the same manner as the above-described embodiment.

[Third Embodiment]
Next, another form of the drive transmission mechanism that rotates the rotary 102 will be described in detail with reference to FIGS. 9 and 10.

  FIG. 9 is a front view showing the configuration of the drive transmission mechanism, and shows a state in which the developing roller 182a is at the developing position facing the photosensitive drum 2. FIG. 10 is a right side view of FIG. 9 viewed from the right. However, in FIG. 9, the main body frame 171 shown in FIG. 10 is not shown. In FIG. 10, the transfer belt 7 and the transfer roller 81 shown in FIG. 9 are not shown.

  In the present embodiment, the above-described regulating member is provided integrally with the photosensitive drum 2. That is, the support rod 2a that supports the photosensitive drum 2 serves as a function of a regulating member that regulates the swing of the rotary. In the present embodiment, the support rod 2a has the function of the regulation roller 105 in the above-described embodiment. Also in this embodiment, the same result as that of the above-described embodiment can be obtained. Other configurations and operations are the same as those in the above-described embodiment.

  The cam 101 rotates integrally with the rotary 102. Then, the contact portions 101e to 101h come into contact with the support rod 2a included in the photosensitive drum 2. As a result, the developing roller 182 is separated from the photosensitive drum 2. On the other hand, as shown in FIG. 9, when the developing roller 182 a is in contact with the photosensitive drum 2, the cam 101 is separated from the support rod 2 a by the separation portion (concave portion) 101 a. In other developing devices as well, when the developing roller is in contact with the photosensitive drum 2, the cam 101 is separated from the support rod 2a at each of the separating portions (concave portions) 101b to 101d.

  Here, the photosensitive drum 2 and the support rod 2a are originally components of the image forming apparatus. In the above-described embodiment, the photosensitive drum 2 and the support rod 2a handle the swing of the rotary 102. Thereby, it is not necessary to provide the regulation roller 105 and the roller holder 106 as the regulation member in the embodiment described above. Therefore, cost reduction and space can be reduced.

  Further, as described in the first embodiment, the contact assisting member described above may be provided on the cam. According to this configuration, when the developing roller is brought into contact with the photosensitive drum 2 in a substantially contact state, component tolerances such as the restriction roller 105 and the roller holder 106 that constitute the restriction member are not applied.

  The regulating member (roller 105, roller holder 106) may be provided integrally with a unit (not shown) that supports the photosensitive drum 2.

  As described above, according to the present embodiment, the regulating member is provided integrally with the photosensitive drum 2 or a unit (not shown) that supports the photosensitive drum 2.

[Fourth Embodiment]
Next, another form of the drive transmission mechanism that rotates the rotary 102 will be described with reference to FIGS. 11 and 12.

  FIG. 11 is a front view showing a schematic configuration of the drive transmission mechanism, in which the developing roller 182a is located at the developing position 18X and is in a developing state. FIG. 12 is a right side view of FIG. 11 viewed from the right direction. However, in FIG. 11, the main body frame 171 shown in FIG. 12 is not shown. In FIG. 12, the transfer belt 7 and the transfer roller 81 shown in FIG. 11 are not shown.

  The present embodiment is a combination of the second embodiment and the third embodiment described above. That is, cams 183 as rotating members (guide members) that rotate integrally with the rotary 102 are provided in the developing devices 18 a to 18 d supported by the rotary 102. Further, a regulating member is provided integrally with the photosensitive drum 2. Here, the support rod 2a that supports the photosensitive drum 2 is configured to function also as a regulating member that regulates the swing of the rotary. Other configurations and operations are the same as those in the above-described embodiment.

  According to this embodiment, the cam 101, the regulation roller 105, the roller holder 106, etc. in the above-described embodiment can be eliminated. Therefore, cost reduction and space can be reduced.

  Also in this embodiment, the above-described contact assisting portion (FIGS. 6A and 6B) may be provided in the same manner as in the above-described embodiment. According to the configuration in which the contact assistant is provided, when the developing roller comes into contact with the photosensitive drum 2 in a substantially contact state, tolerances of components such as the cam 101, the regulation roller 105, and the roller holder 106 are not added.

  In the above-described embodiment, the printer is exemplified as the image forming apparatus, but the present invention is not limited to this. For example, the image forming apparatus may be another image forming apparatus such as a copying machine or a facsimile machine, or another image forming apparatus such as a multi-function machine combining these functions. Further, according to the above-described embodiment, an intermediate transfer member (belt) is used, toner images of respective colors are sequentially transferred onto the intermediate transfer member, and the toner image carried on the intermediate transfer member is used as a recording material. An example of an image forming apparatus that performs batch transfer is illustrated. However, the present invention is not limited to this. For example, an image forming apparatus that uses a recording medium carrier and sequentially transfers the developer images of the respective colors onto the recording medium carried on the recording medium carrier may be used. By applying the present invention to such an image forming apparatus, the same effect as described above can be obtained.

  In each of the embodiments, the developing rollers 182a to 182d develop the electrostatic latent image in a state where they are in contact with the photosensitive drum 2 (so-called contact development). Therefore, the configuration in which the developing rollers 182a to 182d are in contact with the photosensitive drum 2 at the developing position 18X has been described. However, the present invention is not limited to this configuration. The present invention can also be applied to a configuration in which the developing rollers 182a to 182d do not contact the photosensitive drum 2 at the developing position 18X. In the present invention, for example, spacer rollers provided at one end and the other end of the developing rollers 182a to 182d are brought into contact with the end portion of the photosensitive drum 2 at the developing position 18X. Accordingly, the present invention can be applied to a configuration in which the developing roller and the photosensitive drum 2 are brought close to each other.

  According to each of the above-described embodiments, when the developing devices 18a to 18d are moved by the rotation of the rotary 102, the developing device is moved away from the developing position 18X in the crossing direction intersecting the rotation direction B of the rotary 102. The developing device can be moved.

  As described above, according to each of the above-described embodiments, the developing devices 18a to 18d to be supported are moved to the developing position 18X from the rotation direction B of the rotary 102, and the developing devices 18a to 18d are moved in the rotation direction B. Can be moved to the developing position 18X from the intersecting direction intersecting with. As a result, the developing device supported by the rotary 102 can be rotated and moved further away from the photosensitive drum 2 in the direction crossing the rotation direction B.

  Further, according to the above-described embodiments, the developing devices 18a to 18d to be supported are moved away from the developing position 18X in the rotation direction B of the rotary 102, and the developing devices 18a to 18d are intersected with the rotation direction B. Can be moved away from the development position 18X. The developing devices 18a to 18d can be moved in the rotation direction B in a state where the developing devices 18a to 18d are moved away from each other in the crossing direction.

  According to each of the embodiments described above, the developing devices 18a to 18d are moved away from the developing position 18X in the direction intersecting with the rotation direction B of the cam 101 by the rotation of the cam 101 and reach the retracted position. Here, the standby position 18Y is a position where each of the developing devices 18a to 18d is deviated from the developing position in the rotation direction B. The developing device located at the standby position 18Y is also located at the retracted position. The developing devices 18a to 18d located at the retracted position reach the developing position 18X from the intersecting direction intersecting the rotational direction B by the rotation of the cam 101.

Sectional drawing which shows schematic structure of the laser beam printer which is an example of an image forming apparatus The front view which shows the structure of the switching mechanism of the developing device which concerns on 1st Embodiment. The perspective view of the structure shown in FIG. The right view of the switching mechanism of the developing device which concerns on 1st Embodiment. The front view which shifted the phase of the rotation support body of FIG. Fig. 2 is an enlarged view of the main part showing the vicinity of the recess in Fig. The front view which shows schematic structure of the switching mechanism of the developing device which concerns on 2nd Embodiment. The right view of the switching mechanism of the developing device which concerns on 2nd Embodiment. The front view which shows schematic structure of the switching mechanism of the developing device which concerns on 3rd Embodiment. A right side view of a switching mechanism of a developing device according to a third embodiment The front view which shows schematic structure of the switching mechanism of the developing device which concerns on 4th Embodiment. A right side view of a developing device switching mechanism according to a fourth embodiment.

Explanation of symbols

S: Sheet (recording medium)
2 ... electrophotographic photosensitive drum 2a ... support rods 18a to 18d ... developing device 101 ... cam (rotating member)
101a to 101d ... separation part (concave part)
101e to 101h ... contact part 101k ... contact auxiliary part 102 ... rotary (rotary support)
102a ... Gear portion (rotating support gear)
103. Arm (swing member)
104. Arm spring (elastic member)
105… Regulation roller
106 ... roller holder 107 ... shaft 172 ... drive gears 182a to 182d ... developing roller 183 ... cam (rotating member)
183a to 183d ... separation part (concave part)
183e to 183h ... contact portion

Claims (12)

In a color electrophotographic image forming apparatus for forming an image on a recording medium,
An electrophotographic photosensitive drum;
A rotating support for supporting a plurality of developing devices for developing an electrostatic latent image formed on the electrophotographic photosensitive drum, wherein the supporting developing device is rotated from the rotating direction by rotating the electrostatic developing image. A rotating support for sequentially moving the latent image to a developing position for developing the latent image;
A motor,
A swinging member that swingably supports the rotating support;
A rotating member that rotates together with the rotating support that rotates in response to a rotational force from the motor, the developing device supported by the rotating support from the intersecting direction intersecting the rotating direction of the rotating support; A rotating member having a separating portion for moving to the developing position and a contact portion for moving the developing device from the crossing direction to a retracted position for retracting the developing device from the developing position;
In order to move the developing device from the intersecting direction to the developing position, the developing device is placed at a position facing the spaced apart portion that rotates in accordance with the rotation of the rotating member. In order to move the rotating support to the retracted position, it is provided at a position in contact with the contact portion that rotates according to the rotation of the rotating member, and restricts the swinging of the rotating support in a state in contact with the contact portion. A regulating member;
Have
The developing device is positioned at the developing position when the regulating member is separated from the separation portion, and the developing device is located at the retracted position when the regulating member is in contact with the contact portion. As described above, the color electrophotographic image forming apparatus is characterized in that the rotary support swings.   The rotating member is located at one end in the longitudinal direction of the developing device supported by the rotating support, and is provided integrally with the rotating support, and the contact portion and the separation portion are supported by the rotation support. It is alternately arranged along the rotation direction of the body, and the distance between the spaced-apart portion and the rotation center of the rotation support is shorter than the distance between the contact portion and the rotation center of the rotation support. The color electrophotographic image forming apparatus according to claim 1.   The spacing portion is a recess provided at a plurality of locations along the rotation direction of the rotating member, and the recess has a slope that rises from the downstream side toward the upstream side in the rotation direction. The color electrophotographic image forming apparatus according to claim 1, wherein:   4. The color electrophotographic image forming apparatus according to claim 3, wherein the rocking member is rotatably supported by a main body of the image forming apparatus, and supports a rotation center of the rotation support. apparatus.   The rotary support has a rotary support gear provided along the rotation direction thereof, and the swing member is coaxial with a rotation center that rotatably supports the swing member on the main body. 5. The color electrophotographic image forming apparatus according to claim 4, wherein a gear is provided, and the rotary support gear and the swinging member gear mesh with each other.   The restricting member is an elastic roller rotatably supported on a shaft fixed to the main body of the image forming apparatus, and the shaft supporting the elastic roller is parallel to a rotation axis of the rotation support body. 5. The color electrophotographic image forming apparatus according to claim 4, wherein the elastic roller is driven to rotate in contact with a contact portion of the rotating member when the rotating member rotates. .   The rotating support, the swinging member, the rotating member, and the elastic roller are disposed on one end side and the other end side in the longitudinal direction of the developing device supported by the rotating support, and the developing In a state where the apparatus is located at a standby position where development is not performed, the rotary support disposed on the one end side is supported below the elastic roller disposed on the one end side, and The rotation support body arranged on the other end side is supported below the elastic roller arranged on the other end side, whereby the rotation support body is restricted from swinging by the elastic roller. The color electrophotographic image forming apparatus according to claim 6.   The separation portion is configured so that the developing roller has the developing roller in a position substantially the same as the position in contact with the electrophotographic photosensitive drum, in order to position the developing roller of the developing device before contacting the electrophotographic photosensitive drum. The color electrophotographic image forming apparatus according to claim 1, further comprising a contact assisting portion that contacts the regulating member prior to contacting the electrophotographic photosensitive drum.   The color electrophotographic image forming apparatus according to claim 1, wherein the rotating member is provided integrally with the developing device supported by the rotating support.   5. The color electrophotographic image according to claim 1, wherein the regulating member is provided integrally with an electrophotographic photosensitive drum or a unit that supports the electrophotographic photosensitive drum. 6. Forming equipment. In a color electrophotographic image forming apparatus for forming an image on a recording medium,
An electrophotographic photosensitive drum;
A rotating support for supporting a plurality of developing devices for developing an electrostatic latent image formed on the electrophotographic photosensitive drum, wherein the supporting developing device is rotated from the rotating direction by rotating the electrostatic developing image. A rotating support for sequentially moving the latent image to a developing position for developing the latent image;
A motor,
A swinging member that is rotatably supported by the main body of the image forming apparatus, and that supports the rotation supporter in a swingable manner;
A rotating member that rotates together with the rotating support that rotates in response to a rotational force from the motor, the developing device supported by the rotating support from the intersecting direction intersecting the rotating direction of the rotating support; A separation portion for moving the developing device to a developing position and a contact portion for moving the developing device from the crossing direction to a retracting position for retracting the developing device from the developing position are alternately arranged along the rotation direction of the rotating support. The distance between the contact portion and the rotation center of the rotation support is shorter than the distance between the separation portion and the rotation center of the rotation support, and the contact portion is a recess, A rotating member having a slope rising from the downstream side toward the upstream side in the rotation direction;
A rotation support gear provided along the rotation direction of the rotation support;
A swinging member gear that is disposed coaxially with a rotation center that rotatably supports the swinging member on the main body, and meshes with the rotation support gear;
An elastic roller provided at a position in contact with the contact portion that rotates in accordance with the rotation of the rotating member, and at a position facing the separation portion that rotates in accordance with the rotation of the rotating member. An elastic roller disposed so that a rotation axis of the elastic roller is parallel to a rotation axis of the rotating support;
Have
The developing device is positioned at the developing position when the elastic roller is opposed to the separating portion, and the developing device is positioned when the regulating member is in contact with the contact portion. A color electrophotographic image forming apparatus, wherein the rotary support swings so as to be located at a retracted position.   The rotating support, the swinging member, the rotating member, and the elastic roller are disposed on one end side and the other end side in the longitudinal direction of the developing device supported by the rotating support, In a state where the developing device is located at a standby position where development is not performed, the rotary support disposed on the one end side is supported below the elastic roller disposed on the one end side, and The rotation support body arranged on the other end side is supported below the elastic roller arranged on the other end side, whereby the rotation support body is restricted from swinging by the elastic roller. The color electrophotographic image forming apparatus according to claim 12, wherein:

Images