JP5847553B2 - Drive transmission device and image forming apparatus using the same - Google Patents

Description

  The present invention relates to a drive transmission device capable of releasing transmission of a drive force from a drive member rotated by a drive source to a driven member, and an image forming apparatus using the drive transmission device.

  2. Description of the Related Art Conventionally, in image forming apparatuses such as copying machines, printers, and facsimiles, a drive transmission device that performs an intermittent rotation operation is used for a contact-separation mechanism of a transfer roller, a sheet pickup mechanism of a sheet feeding unit, and the like. In such a drive transmission device, it is common to use an electromagnetic clutch, a dedicated motor, etc. in order to perform an intermittent rotation operation. There exists a structure shown in patent document 1.

  FIG. 5 is a simplified view of a conventional drive transmission device described in Patent Document 1. In FIG. This configuration will be described. A drive gear (drive member) 22 that is rotationally driven in the direction of arrow A by a drive source (not shown) and a driven gear (driven member) 23 that can rotate coaxially with the drive gear 22 are provided. The driven gear 23 holds a drive transmission member 24 that can move between a position that rotates with respect to the driven gear 23 and engages with the drive gear 22 and a position that is disengaged.

  As shown in FIG. 5A, in the state where the engaging portion 24 a of the drive transmission member 24 is engaged with the drive gear 22, the driving force is transmitted from the drive gear 22 to the driven gear 23 via the drive transmission member 24. Communicated. For this reason, the driven gear 23 and the drive transmission member 24 rotate integrally with the drive gear 22 in the arrow A direction.

  When releasing the transmission of the driving force to the driven gear 23, as shown in FIG. 5B, the contact member 17 is moved to a position where it contacts the drive transmission member 24, and the drive transmission member 24 is locked. Thus, the engagement between the drive transmission member 24 and the drive gear 22 is released. By doing so, the transmission of the driving force from the driving gear 22 to the driven gear 23 is released.

JP-A-3-158328

  In Patent Document 1, the drive transmission member 24 is urged by a spring 25 in a direction to mesh with the drive gear 22 so that the engagement portion 24a of the drive transmission member 24 is reliably engaged with the drive gear 22. Therefore, in order to cancel the transmission of the driving force to the driven gear 23, the driving transmission member 24 is moved against the urging force of the spring 25 when the abutting member 17 abuts against the driving transmission member 24. It is necessary to release (retract) from 22 and release the engagement.

  Here, in the configuration of Patent Document 1, the driving force is not transmitted from the driving gear 22 to the driven gear 23 at the moment when the engagement of the driving gear 22 with the tip of the engaging portion 24a of the driving transmission member 24 is disengaged. The rotation of the driven gear 23 is immediately stopped by the load applied to the gear 23. For this reason, when the rotation of the driven gear 23 stops, there is a possibility that the tip of the engaging portion 24a of the drive transmission member 24 cannot move to a position away (retracted) from the drive gear 22 with a sufficient distance.

  On the other hand, normally, there is a backlash or other backlash between the driven gear 23 and a member on the downstream side in the drive transmission direction of the driven gear 23, and the driven gear 23 is in a state where no driving force is transmitted from the drive gear 22. Will be able to rotate backwards by backlash. For this reason, when the driven gear 23 rotates in the reverse direction due to vibration or the like in the apparatus main body, the tip of the engaging portion 24a of the drive transmission member 24 collides with the driving gear 22 that continues to rotate by the driving source, and the collision sound Etc. may occur.

  Therefore, in view of the above problems, the present invention provides a drive transmission device that uses a driven member that holds a drive transmission member that can be engaged with the drive member. The purpose is to further suppress this.

The present invention comprises a driving member that rotates by a driving force from a driving source, a driven member that rotates coaxially with the driving member in response to the driving force from the driving member, and is held movably with respect to the driven member, A drive transmission member that engages with the drive member; and a contact member that contacts the drive transmission member to release the engagement between the drive transmission member and the drive member; and the driving force from the drive member through the drive transmitting member and the drive transmission member is engaged with the said drive member by the drive transmission member is separated into the driven member is transmitted, the abutting member In the drive transmission device in which transmission of the driving force from the drive member to the driven member is released when the engagement between the drive transmission member and the drive member is released by the contact of the drive transmission member The driven member It has a rotation means for rotating,
The rotating means moves the driven member in the state in which the drive transmission member is in contact with the contact member so that the drive transmission member moves in a direction in which the engagement with the drive member is released. It is made to rotate with respect to.

According to the present invention, the drive transmission device using a driven member to hold the engageable drive transmission member to the drive member, the drive transmission member is securely retracted from the drive member, be further suppressed the generation of the collision sound it can.

1 is a schematic sectional view of an image forming apparatus. The perspective view of a drive transmission device. (A) The figure which looked at the drive transmission device from the axial direction of the rotation center. (B) The figure which looked at the drive transmission device from the axial direction of the rotation center. (A) The figure which looked at the drive transmission device from the axial direction of the rotation center. (B) The figure which looked at the drive transmission device from the axial direction of the rotation center. (A) The figure which simplifies and shows the conventional drive transmission device. (B) The figure which simplifies and shows the conventional drive transmission device.

<First Embodiment>
A first embodiment of the present invention will be described. In the present embodiment, a drive transmission device mounted on an electrophotographic image forming apparatus will be described. The image forming apparatus will be described first before describing the drive transmission device.

[Image forming apparatus]
FIG. 1 is a schematic sectional view of the image forming apparatus. This image forming apparatus is a tandem type electrophotographic color laser printer using an intermediate transfer belt (intermediate transfer member).

  The image forming apparatus 600 includes four image forming units Y, M, C, and K that form toner images of yellow, magenta, cyan, and black, and these image forming units Y, M, C, and K are images. In the forming apparatus main body 600, they are arranged in parallel from left to right.

  Each of the image forming units Y, M, C, and K is an image forming unit of an electrophotographic image forming system, and each of the image forming units except for forming a different color toner image on the photosensitive drum of each image forming unit. The configuration of the parts is the same. Each image forming unit has a photosensitive drum 1 (1Y, 1M, 1C, 1K). Further, in each image forming unit, a charging roller 2 (2Y, 2M, 2C, 2K) and a developing roller 3 (3Y, 3M, 3C, 3K) are provided around the photosensitive drum 1 as process means acting on the photosensitive drum 1. And a transfer roller 7 (7Y, 7M, 7C, 7K) and a cleaning blade 8 (8Y, 8M, 8C, 8K). Further, a laser scanner 4 for irradiating each photosensitive drum 1 with laser light corresponding to image information is provided below each photosensitive drum 1.

  Next, image formation in each image forming unit will be described. Each photosensitive drum 1 is driven to rotate clockwise in FIG. In this state, the photosensitive drum 1 is charged by the charging roller 2 and irradiated with laser light from the laser scanner 4 to form a latent image. A toner image is formed on the surface of the photosensitive drum 1 by attaching toner that adheres to the developing roller 3 to the latent image. A yellow toner image, which is a color separation component color of the full-color image, is formed on the surface of the photosensitive drum 1Y of the image forming unit Y, and a magenta toner image is formed on the surface of the photosensitive drum 1M of the image forming unit M. Further, a cyan toner image is formed on the surface of the photosensitive drum 1C of the image forming unit C, and a black toner image is formed on the surface of the photosensitive drum 1C of the image forming unit C.

  On the other hand, an intermediate transfer belt 601 to which a toner image is transferred from each photosensitive drum 1 is disposed above the image forming portions Y, M, C, and K. The intermediate transfer belt 601 has a winding roller 5 disposed on the image forming unit Y side, a winding roller 6 disposed on the image forming unit K side, and a secondary transfer facing member disposed above the hanging roller 6. The roller 602T is stretched between the three parallel-arranged rollers. The rolling roller 6 is a roller for driving the intermediate transfer belt 601 in the direction of arrow B (counterclockwise) so that the speed of the surface of the intermediate transfer belt 601 is substantially the same as the speed of the surface of each photosensitive drum 1. Rotation is driven by a drive source (not shown).

  A primary transfer roller 7 is disposed between the winding rollers 5 and 6 so as to face the photosensitive drums 1 of the image forming portions Y, M, C, and K with the intermediate transfer belt 61 interposed therebetween. A nip portion T1 is formed. A primary transfer bias is applied at the primary transfer nip to transfer the toner image on each photosensitive drum 1 onto the intermediate transfer belt 601.

  A secondary transfer roller 602 is disposed downstream of the primary transfer nip T1 in the rotation direction of the intermediate transfer belt 601 so as to face the secondary transfer counter roller 602T with the intermediate transfer belt 61 interposed therebetween. The secondary transfer roller 602 presses the secondary transfer counter roller 602T via the intermediate transfer belt 601, and the intermediate transfer belt 601 and the secondary transfer roller 602 form a secondary transfer nip portion T2. The toner image on the intermediate transfer belt 601 is transferred onto a sheet conveyed to the secondary transfer nip T2 by applying a secondary transfer bias at the secondary transfer nip T2.

  An intermediate transfer belt cleaner 603 is disposed at a position facing the winding roller 5 downstream of the intermediate transfer belt 601 in the rotation direction of the secondary transfer nip T2. The intermediate transfer belt cleaner 603 brings the cleaning blade into contact with the outer surface of the intermediate transfer belt 601 and scrapes off the remaining toner that is not transferred at the secondary transfer nip portion T2.

  Reference numeral 604 denotes a fixing device including a pressure roller pair of a fixing roller (heating roller) 604a and a pressure roller 604b.

  Next, a process for forming a four-color toner image on the sheet S will be described. Reference numeral 605 denotes a control board as control means for controlling the image forming apparatus, and controls an image forming operation of the image forming apparatus. The control substrate 605 forms yellow, magenta, cyan, and black toner images on the photosensitive drums 1 of the image forming units Y, M, C, and K based on the print start signal. Each toner image is sequentially superimposed and transferred onto the intermediate transfer belt 601 at the primary transfer nip T1, forming four color toner images on the intermediate transfer belt 601, and four-color toner images onto the secondary transfer nip T2. Move on.

  On the other hand, one sheet (recording material) S stacked and housed in the sheet feeding cassette 9 is separated and fed by the rotational driving of the sheet feeding roller 10 and conveyed to the registration roller pair 11. The registration roller pair 11 introduces the sheet S into the secondary transfer nip T2 in accordance with the arrival of the four color toner images on the intermediate transfer belt 601 at the secondary transfer nip T2. Then, the four color toner images on the intermediate transfer belt 601 are transferred onto the sheet S by the secondary transfer bias. The sheet S exiting the secondary transfer nip portion T2 is conveyed to the fixing device 604 and heated and pressed to fix the unfixed toner image on the sheet S. In this manner, four color toner images are formed on the sheet S.

  Incidentally, in the image forming apparatus 600, there is a possibility that the photosensitive drums 1Y, 1M, and 1C of the image forming units Y, M, and C are rubbed against the intermediate transfer belt 601 and worn out during monochromatic image formation (monochrome printing). Therefore, in order to prevent this, a primary transfer roller contact / separation mechanism (not shown) for bringing the primary transfer rollers 7Y, 7M, and 7C into contact with or separating from the intermediate transfer belt 601 is provided. The primary transfer roller contact / separation mechanism includes a cam, and is configured to switch between a contact state and a separation state between the primary transfer roller 7 and the intermediate transfer belt 601 by changing the rotational phase of the cam. The drive transmission device of this embodiment is used in a part of a gear train that intermittently transmits a driving force to the cam and rotates the cam by a predetermined angle at a predetermined timing.

[Drive transmission device]
Next, this drive transmission device will be described. FIG. 2 is a perspective view of the drive transmission device. This apparatus has an input gear (drive member) 701, an output gear (driven member) 702, an urging lever 703, and a solenoid SL. The input gear 701 is drivingly connected to a motor (drive source) (not shown) via a gear 707 and is rotated by a driving force from the motor. The output gear 702 is a cam drive that transmits a driving force to a cam of a primary transfer roller contact / separation mechanism (not shown) for switching between a contact state and a separation state of the primary transfer roller 7 via the gear 708. Drive connected to the gear train.

  Both the input gear 701 and the output gear 702 rotate coaxially around the rotation center 709. A drive transmission claw 705 is integrally formed around the rotation axis of the input gear 701. The output gear 702 rotates and swings around a shaft 702 a different from the rotation center 709 on the side surface, and holds a drive transmission lever (drive transmission member) 704 as an engagement means that can be engaged with the drive transmission claw 705. To do. On the outer periphery of the output gear 702, a cam portion 706 having a cam surface 706a is integrally formed. The urging lever (pressing member) 703 pulled by the spring 711 presses the cam surface 706a to give a rotational force to the output gear 702. The cam portion only needs to be rotatable integrally with the output gear 702. For example, a member including the cam portion 706 may be fixed to the output gear 702 with an adhesive or the like.

[Operation of drive transmission device]
Next, the intermittent drive of the output gear 702 using this drive transmission device will be described with reference to FIGS.

  FIG. 3A shows a standby state in which the energization of the solenoid SL is released and a flapper (contact member) 207 serving as a locking member for locking the drive transmission lever 704 is locking the drive transmission lever 704. Yes. At this time, the drive transmission lever 704 is in the disengaged position where the engagement between the drive transmission claw 705 and the drive transmission lever 704 is released. For this reason, drive is not transmitted from the input gear 701 to the output gear 702, the output gear 702 is stopped, and only the upstream gears in the drive transmission direction such as the input gear 701 and the gear 707 are rotating. The input gear 701 rotates in the direction of arrow C.

  Next, the solenoid SL is energized, and the flapper 207 is retracted from the drive transmission lever 704 to release the engagement with the drive transmission lever 704. Then, a spring 710 provided between the output gear 702 and the drive transmission lever 704 presses the drive transmission lever 704 and rotates it in the direction of the arrow D1, so that the drive transmission lever 704 moves to the engagement position and the drive transmission claw 705. Engage with. With this engagement, as shown in FIG. 3B, the input gear 701 and the output gear 702 are coupled via the drive transmission lever 704 and integrally start to rotate in the direction of arrow C, and driven from the output gear 704. A driving force is transmitted to the output gear 708. The reason why the spring 710 presses the drive transmission lever 704 will be described later.

  Thereafter, the energization of the solenoid SL is released, and the retracted flapper 207 returns to the locking position where the drive transmission lever 704 can be locked. In this state, as shown in FIG. 4A, when the drive transmission lever 704 that rotates integrally with the output gear 702 returns to the position where it abuts against the flapper 207, one end of the drive transmission lever 704 is caused by the flapper 207. The part 704a is locked. The drive transmission lever 704 is pulled by the drive transmission claw 705 because the other end 704b is engaged with the drive transmission claw 705 at the moment when the one end 704a contacts the flapper 207. For this reason, the drive transmission lever 704 rotates in the direction D2 until the engagement between the other end 704b and the drive transmission claw 705 is released with the one end 704a contacting the flapper 207 as a fulcrum. When the engagement is released, the driving force is not transmitted to the output gear 702, so that the output gear 702 stops.

  Here, in the conventional configuration, when the engagement between the drive transmission claw 705 and the drive transmission lever 704 is disengaged and the output gear 702 stops, the drive transmission lever 704 can no longer be retracted from the drive transmission claw 705. For this reason, when the output gear 702 stops, there exists a possibility that the drive transmission lever 704 may be in a state where it is not retracted with a sufficient distance from the drive transmission claw 705. When this happens, the other end 704b of the drive transmission lever 704 collides with the tip of the drive transmission claw 705 that continues to rotate, generating a noise, which causes noise generation.

  Therefore, in the present embodiment, as shown in FIG. 4B, a biasing lever 703 biased by a spring 711 presses the cam surface 706a of the cam portion 706 to apply a rotational force to the output gear 702. Rotate. Then, by the rotation of the output gear 702, the drive transmission lever 704 is retracted with a sufficient distance from the drive transmission claw 705. The urging lever 703 is rotatable about a shaft 703a.

  More specifically, the drive transmission lever 704 has one end 704a in contact with the flapper 207 and the other end 704b engaged with the drive transmission claw 705, and the tip of the urging lever 703 has the inclined portion L of the cam surface 706a. Press in the direction of arrow E. By pressing the inclined portion L of the cam surface 706a in this way, a rotational force is applied to the output gear 702, and the output gear 702 is rotated in the C direction. As the output gear 702 rotates, the shaft 702a also rotates around the rotation center 709 in the C direction. With this rotational force, the drive transmission lever 704 is rotated in the D2 direction with the one end 704a as a fulcrum, and is further rotated in the D2 direction after the other end 704b and the drive transmission claw 705 are disengaged. For this reason, the other end 704 b of the drive transmission lever 704 can be retracted with a sufficient distance from the drive transmission claw 705.

  The length and inclination of the inclined portion L of the cam surface 706a are set so that the rotation of the output gear 702 stops at an appropriate position where the other end 704b of the drive transmission lever 704 is at a sufficient distance from the drive transmission claw 705. Yes.

  In this way, the drive transmission lever 704 is retracted from the drive transmission claw 705. When the retracting operation of the drive transmission lever 704 is viewed from the output gear 702, the other end 704b of the drive transmission lever 704 is removed from the drive transmission claw 705. It is rotating around the shaft 702a to leave. At this time, the drive transmission lever 704 pushes and shrinks the spring 710 while rotating. Therefore, when the output gear 702 stops, the spring 710 is pressed and contracted. When the flapper 207 releases the lock of the drive transmission lever 704, the spring 710 is released and presses the drive transmission lever 704 as described above. And rotate.

  Further, the output gear 702 that is stopped by being locked by the flapper 207 is subjected to a load by a cam or a gear train (not shown) on the downstream side in the drive transmission direction, and the load rotates the output gear 702. Rotation resistance of For this reason, the spring pressure of the spring 710 is set to be smaller than its rotational resistance, and the output gear 702 is prevented from rotating clockwise in the drawing by the force of the spring 710.

  In this embodiment, the output gear is rotated in the C direction by pressing the urging lever 703 on the cam portion 706. However, the output gear may be rotated in the C direction by an actuator such as a solenoid at the timing when the flapper 207 is brought into contact with the one end 704a of the drive transmission lever 704.

  In the present embodiment, the example in which the drive transmission device of the present invention is applied to the primary transfer contact / separation mechanism of the image forming apparatus is shown, but the drive transmission device of the present invention is not limited to this. That is, the drive transmission device of the present invention switches the drive of the paper feed unit of the image forming apparatus, the contact / separation mechanism between the developing roller 3 and the photosensitive drum 1, the drive switching of the toner replenishing unit, and other drive transmission units. The present invention can be applied to devices having a drive transmission unit other than the image forming apparatus.

  As described above, in the present embodiment, when the drive transmission lever 704 is locked to the flapper 207, the biasing lever 207 presses the inclined portion L of the cam surface 706a and rotates the output gear 702. The drive transmission lever 704 can be reliably retracted to a position at a sufficient distance from the drive transmission claw 705. And by retreating reliably in this way, it is possible to solve mechanical problems such as reliable release of drive transmission and prevention of collision noise.

207 Flapper (contact member)
701 Input gear (drive member)
702 Output gear (driven member)
703 Energizing lever (pressing member)
704 Drive transmission lever (drive transmission member)
705 Drive transmission claw 706 Cam portion 706a Cam surface 710 Spring 711 Spring

Claims (7)

A driving member that is rotated by a driving force from a driving source;
A driven member that receives a driving force from the driving member and rotates coaxially with the driving member;
A drive transmission member held movably with respect to the driven member and engaged with the drive member;
A contact member that contacts the drive transmission member in order to release the engagement between the drive transmission member and the drive member;
A driving force from the drive member to the driven member via the drive transmission member when the contact member is separated from the drive transmission member and the drive transmission member is engaged with the drive member. If the engagement between the drive transmission member and the drive member is released by the contact between the contact member and the drive transmission member, the drive force from the drive member to the driven member is reduced . In the drive transmission device in which transmission is released,
A rotating means for rotating the driven member;
The rotating means moves the driven member in the state in which the drive transmission member is in contact with the contact member so that the drive transmission member moves in a direction in which the engagement with the drive member is released. A drive transmission device, wherein The driven member includes a shaft portion serving as a rotation center of the drive transmission member at a position different from a rotation center of the driven member, and the drive transmission member rotates and moves around the shaft portion. Item 2. The drive transmission device according to Item 1 . The rotating means includes a cam portion that rotates integrally with the driven member, and a pressing member that presses the cam portion,
3. The drive transmission member is separated from the drive member by the pressing member pressing the cam portion in a state where the drive transmission member is in contact with the contact member. The drive transmission device described in 1. 4. The drive according to claim 3, wherein the drive transmission member includes one end portion that contacts the contact member on one end side, and an engagement portion that engages the drive member on the other end side. Transmission device. Biasing means for urging the drive transmission member in a direction in which the drive transmission member is engaged with the drive member, and the drive by the urging means in a state where the abutment member is not in contact with the drive transmission member. drive transmission device according to any one of claims 1 to 4 transmitting member and wherein the engaging said drive member. The drive according to any one of claims 1 to 5, wherein the contact member is movable by a solenoid to a position where the contact member is in contact with the drive transmission member and a position where the contact member is separated from the drive transmission member. Transmission device . An image forming apparatus having a drive transmission device according to any one of claims 1 to 6.

Images