JP2005331548A - Coupling device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coupling device with which couplings engage in normal positions with a simple configuration and an image forming apparatus equipped therewith. <P>SOLUTION: The coupling device, in which a driving side coupling 26a and driven side coupling 26b existing in spaced positions move to the engageable positions by relative movements to the rotational axis direction and the driving side coupling 26a rotate to engages the driven side coupling 26b and torque is thereby transmitted, has a relation T 1>T 2 when the time required for the driving side coupling 26a existing in a state movable to the engageable position to rotate until the coupling engages the driven side coupling 26b is defined as T 1 and the time required for the driving side coupling 26a and the driven side coupling 26b to relatively move from the spaced positions to the engageable positions as T 2. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a coupling device that can be engaged with each other to transmit a driving force, and an image forming apparatus such as a copying machine, a printer, and a facsimile machine including the same.

  FIG. 13 schematically shows an example of a conventional color image forming apparatus using an electrophotographic process, in this example, a color laser printer.

  This color laser printer includes process cartridges 100Y, 100M, 100C, and 100K that are four image forming portions of yellow (Y), magenta (M), cyan (C), and black (K). The images formed on the photosensitive drums 101Y, 101M, 101C, and 101K, which are image carriers in the process cartridges 100Y, 100M, 100C, and 100K, are once continuously transferred to the intermediate transfer member 102 that is the second image carrier. This is a 4-drum type (in-line) printer that obtains a full-color print image by multiple transfer.

  At this time, if the process cartridges 100Y, 100M, 100C, and 100K are stacked in an up-and-down direction, the installation area can be reduced, and the advantages of space saving in the office are great, and the color laser printer is personalized. But it is an effective means.

  In this color laser printer, driving is transmitted to the intermediate transfer member 102 and the process cartridges 100Y, 100M, 100C, and 100K by coupling, and the coupling is engaged when the process cartridges 100Y, 100M, 100C, and 100K are attached and detached. Is configured to mesh when one of the couplings arranged in the apparatus body rotates to the coupling meshing position (Patent Document 1).

JP-A-6-332285

  However, in the above-described conventional example, when the coupling is not engaged, such as when the process cartridge is replaced, the rotation is performed at the normal operation speed at the start of driving, and the coupling is performed when the driving-side coupling is rotated to the engagement position. It jumped out and transmitted the coupling and meshing drive on the driven side.

  At this time, when the coupling on the driving side first rotates to the meshing position, even if it does not mesh with the coupling on the driven side, it will mesh when it continues to rotate and then rotates to the meshing position. In addition, it may be configured to mesh between several revolutions after starting driving.

  In addition, in the case of an apparatus having a plurality of electrophotographic photoreceptors and intermediate transfer bodies, such as an in-line color image forming apparatus, the reliability of the engagement operation of the coupling that transmits driving to each photoreceptor drum or intermediate transfer body Is highly demanded.

  However, even if one of the couplings has a poor meshing or it takes time to engage, and the coupling has made several turns in the meantime, for example, either the photosensitive drum or the intermediate transfer member If either of them becomes poorly coupled, or if there is a time lag in the coupling, there will be problems such as rubbing at the abutting part, generating a rubbing memory, or scratching the abutting surface. It was.

  Also, when the coupling is engaged, if it is engaged and transmitted while it is protruding partway without protruding to the proper engagement position, the coupling may come off during rotation or the coupling may rotate. However, it gradually moves to the normal meshing position, driving transmission becomes unstable, and the rotational speed on the driven side also becomes unstable. As a result, image defects due to rotational fluctuations have also been a problem.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a coupling device in which a coupling is engaged at a normal position with a simple configuration and an image forming apparatus including the coupling device.

  A representative means in the present invention for solving the above-described problem is that the driving side coupling and the driven side coupling in the separated position move relative to each other in the rotation axis direction and move to the engageable position, and the driving side In a coupling device in which a coupling rotates and engages with the driven side coupling to transmit a rotational force, the driving side coupling in a state movable to the engageable position is the driven side The time required for rotation until engaging with the coupling is T1, and the time required for relative movement of the driving side coupling and the driven side coupling from the separated position to the engageable position is T2. Then, it has a relationship of T1> T2.

  In the present invention, the time required for the drive side coupling that is movable to the engageable position to rotate until the drive side coupling engages with the driven side coupling is determined by the drive side coupling and the driven side coupling. Since it is longer than the time required for the relative movement from the separated position to the engageable position, the reliability at the time of coupling engagement is improved, and the drive is not transmitted halfway.

  Next, an image forming apparatus using the coupling device according to an embodiment of the present invention will be specifically described. In the present embodiment, a color image forming apparatus that loads four process cartridges to form a color image is illustrated.

[Overall Description of Image Forming Apparatus]
First, the overall configuration of the image forming apparatus will be outlined. FIG. 12 is a schematic cross-sectional view of the color laser printer according to this embodiment.

  As shown in FIG. 12, the color laser printer of this embodiment (hereinafter referred to as “printer”) rotates at a constant speed for each color of yellow (Y), magenta (M), cyan (C), and black (K). An image forming unit having an electrophotographic photosensitive drum (hereinafter referred to as a “photosensitive drum”), and a recording medium P which is developed by the image forming unit and holds a color image which has been multiple-transferred and is fed from the feeding unit And a belt-like intermediate transfer belt 5 which is an intermediate transfer rotating body for transferring.

  The photosensitive drum 1 (1Y, 1M, 1C, 1K) is rotationally driven in a counterclockwise direction as shown in FIG. 12 by driving means (not shown).

  The periphery of the photosensitive drum 1 is irradiated with a laser beam based on image information, a charging device 2 (2Y, 2M, 2C, 2K) for uniformly charging the surface of the photosensitive drum 1 in order according to the rotation direction, A scanner unit 3 (3Y, 3M, 3C, 3K) that forms an electrostatic latent image on the photosensitive drum 1, and a developing unit 4 (4Y, 4M, 4C) that develops a toner image by attaching toner to the electrostatic latent image. , 4K), a primary transfer roller 12 (12Y, 12M, 12C, 12K) for transferring the toner image on the photosensitive drum 1 to the intermediate transfer belt 5 at the primary transfer portion T1, and remains on the surface of the photosensitive drum 1 after transfer. A photoreceptor unit 6 (6Y, 6M, 6C, 6K) having a cleaning blade for removing transfer residual toner is disposed.

  At the time of image formation, the intermediate transfer belt 5 stretched around the rollers 14, 15, 16a, and 16b rotates, and the color toner images formed on the respective photosensitive drums are primary-transferred superimposed on the intermediate transfer belt 5. As a result, a color image is formed.

  The recording medium is conveyed to the secondary transfer portion by the conveying means so as to be synchronized with the primary transfer to the intermediate transfer belt 5. The conveying means includes a feeding cassette 17 that stores a plurality of recording media P, a feeding roller 18, a separation pad 19, and a registration roller pair 21. At the time of image formation, the feeding roller 18 is driven and rotated in accordance with the image forming operation to separate the recording media P in the feeding cassette 17 one by one, and the registration roller pair 21 performs the secondary operation in synchronization with the image forming operation. Transport to the transfer section.

  A swingable secondary transfer roller 13 is disposed in the secondary transfer portion T2. The secondary transfer roller 13 can move substantially in the vertical direction. When the image is transferred, it is pressed against the intermediate transfer belt 5 through the recording medium P with a predetermined pressure. At this time, a bias is applied to the secondary transfer roller 13 at the same time, and the toner image on the intermediate transfer belt 5 is transferred to the recording medium P.

  Since the intermediate transfer belt 5 and the secondary transfer roller 13 are driven, the recording medium P sandwiched between the two is conveyed at a predetermined speed in the left direction shown in FIG. It is conveyed to the fixing unit 8 which is the next process. In the fixing unit 8, heat and pressure are applied to fix the transferred toner image on the recording medium. The recording medium is discharged onto a discharge tray 10 on the upper surface of the apparatus by a discharge roller pair 9.

  The process cartridge 7 (7Y, 7M, 7C, 7K) includes a photosensitive drum 1, a charging device 2, a developing unit 4, and a photosensitive unit 6. The process cartridge 7 is attached / detached by opening / closing the opening / closing cover 11 of the image forming apparatus main body 20.

  The image forming apparatus main body 20 is provided with an opening / closing cover 11 so as to be rotatable, and the opening / closing cover 11 is provided with an intermediate transfer belt 5 so as to be rotatable. Accordingly, the process cartridge 7 can be attached to and detached from the image forming apparatus main body 20 with the opening / closing cover 11 and the intermediate transfer belt 5 being opened. The process cartridge 7 is configured such that a guide rail portion (not shown) provided in the image forming apparatus main body 20 and an insertion guide portion (not shown) provided in the process cartridge 7 are engaged with each other. The main body 20 can be attached and detached.

{Coupling configuration}
When the process cartridge is mounted, drive transmission from the apparatus main body 20 to the process cartridge 7 and the intermediate transfer belt 5 is performed. In this embodiment, the plurality of photosensitive drums 1 and the intermediate transfer belt 5 are configured to be driven by a single driving source, and the driving force is transmitted via a coupling device. Next, the configuration of the coupling device will be described.

  FIG. 2 is an explanatory view showing the shape of the coupling 26 of this embodiment. The driven side coupling 26b of the coupling 26 has a triangular convex shape as shown in FIG. 2 (a), and the driving side coupling 26a has a triangular concave shape as shown in FIG. 2 (b). It has become. As shown in FIG. 1, when the phases of the triangles are in phase, they are engaged to transmit drive.

  The coupling 26 is used for driving transmission to the photosensitive drum 1 for four colors and the intermediate transfer belt 5. When the process-side coupling 26a and the intermediate transfer belt unit 23 are attached / detached, the drive side coupling 26a is normally in the retracted position (separated position) as shown in FIG. It has moved to the meshing position (engageable position).

  The connection / disconnection means 27 moves from the meshing position to the retracted position. The connection / disconnection means 27 is interlocked with the opening operation of the opening / closing cover 11, and the coupling 26 is detached by opening the opening / closing cover 11, so that the user can easily attach and detach the unit. On the other hand, the movement from the retracted position to the meshing position is performed by a spring force.

(Coupling engagement)
When the open / close cover 11 is closed, such as after the process cartridge 7 and the intermediate transfer belt unit 23 are replaced or jammed, the drive side coupling 26a is driven and rotated by a motor which is a drive source (not shown). Then, when the phase of the driving side coupling 26a and the driven side coupling 26b is in a fitting relationship as shown in FIG. The side coupling 26b jumps out to the meshing position and the driving force can be transmitted.

  Here, as shown in FIG. 1, the angle θ indicates an angle that can be engaged with the driven side coupling 26b when the driving side coupling 26a rotates. A time required for the drive side coupling 26a that is movable from the retracted position to the meshing position to rotate by the angle θ is T1. Further, when the time required for the drive side coupling 26a to move from the retracted position to the meshing position is T2, in this embodiment, the relationship of T1> T2 is established.

  Here, the time T1 depends on the rotational speed of the coupling 26, and the time T2 depends on the spring force of the spring 31 applied to the drive side coupling 26a. However, increasing the spring force that causes the drive side coupling 26a to jump out to the meshing position results in resistance when the opening / closing cover 11 is opened, and the operating force of the opening / closing cover 11 increases. Therefore, in this embodiment, the drive side coupling 26a is set to the minimum spring force that can surely jump out to the meshing position.

  Therefore, T1 must be set larger than the drive-side coupling 26a popping-out time T2 when the minimum spring force is used. Therefore, in the present embodiment, the motor drive speed is set so that the rotation speed of the drive side coupling 26a at the time of meshing is lower than the rotation speed at the time of normal image formation. Furthermore, the slow rotational speed setting is from the start of rotation of the drive source until the coupling 26 is engaged, that is, only during the rotation of the number of revolutions necessary for the coupling 26 to be engaged, and thereafter the normal rotational speed is increased. It is set to rotate at high speed. As a result, the coupling can be reliably engaged without slowing the image forming speed.

  By configuring as described above, after the driving side coupling 26a and the driven side coupling 26b are in phase as shown in FIG. 1, before the driving side coupling 26a moves from the retracted position to the meshing position. Further, the drive side coupling 26a does not rotate more than the angle θ (rotation angle at which the engagement state is established) shown in FIG. Therefore, the coupling 26 can be reliably engaged at the normal engagement position when the phases are matched, so that the operational reliability of the coupling 26 can be improved. Further, it is possible to prevent image defects due to unstable meshing.

  By driving the drive transmission to the plurality of process cartridges and the intermediate transfer belt by a single motor, the rotational speed control of each drive side coupling can be easily performed.

(Release coupling)
Next, the coupling disengagement when the opening / closing cover 11 is opened and the process cartridge is replaced will be described.

  In the present embodiment, as shown in FIG. 5, when the opening / closing cover 11 is opened, the coupling 26 that transmits the drive to the process cartridge 7 is cut during the time until the cartridge holding member 30 starts moving. .

  In addition, the coupling 26 that transmits the drive to the intermediate transfer belt unit 23 operates the connecting / disconnecting means 27 (27Y, 27M, 27C, 27K) in conjunction with the operation of releasing the lever that unlocks the opening / closing cover 11. Then, the drive side coupling 26a is moved to the retracted position. Therefore, the opening / closing cover 11 can be opened without any problem, and the cartridge holding member 30 can be moved to the cartridge attaching / detaching position β shown in FIG.

  Next, the operation of the intermediate transfer belt unit 23 and the process cartridge 7 by opening / closing the opening / closing cover 11 will be described.

  6 is a cross-sectional view of the state in which the open / close cover 11 is open, FIG. 7 is a cross-sectional view of the state in which the open / close cover 11 is closed, and FIG. 8 is a configuration diagram of the state in which the open / close cover 11 is closed.

  As shown in FIGS. 6 and 7, the apparatus main body 20 has an opening / closing cover 11, an intermediate transfer belt unit 23 in a form of being housed in the opening / closing cover 11, and a rotation provided on the lower side of the apparatus. The process cartridge 7 and the intermediate transfer belt unit 23 can be accessed by opening the opening / closing cover 11 clockwise about the center 70.

  As shown in FIG. 6, each process cartridge 7 can be stored in a cartridge holding member 30 provided on the left and right side plates, and the cartridge holding member 30 is located with respect to a rotation center 80 provided on the upper side of the left and right side plates. It is attached to the apparatus main body so as to be freely rotatable.

  As shown in FIG. 8, the opening / closing cover 11 and the cartridge holding member 30 are connected to each other by two link members (a first link 71 and a second link 72). One end side 71 a of the first link 71 is rotatably connected to the opening / closing cover 11, and the other end side 71 b is rotatably connected to the second link 72. One end side 72b of the second link 72 is connected to the first link 71 and the other end side 72a is rotatably connected to the cartridge holding member 30.

  By the link mechanism, the cartridge holding member 30 moves between two positions: a state in which the open / close cover 11 is closed, that is, an image forming position α shown in FIG. 7, and an open state, that is, a cartridge attaching / detaching position β shown in FIG. be able to.

  The open / close cover 11 is closed as shown in FIG. 9 at the time of image formation, and each process cartridge 7 is held in the cartridge holding member 30 in the vertical direction in the apparatus main body. At this time, the bearing position of the photosensitive drum 1 of the process cartridge 7 is determined to abut against the abutting member 90 (90Y, 90M, 90C, 90K) disposed on the left and right side plates.

  Further, as shown in FIG. 9, a lock lever 82 is rotatably provided below the cartridge holding member 30 and is urged counterclockwise by a tension spring 83 (not less than a predetermined value). A stopper is provided to prevent rotation in the counterclockwise direction). When the open / close cover 11 is closed, the lock lever 82 is locked by locking the locking portion 30a provided at the lower portion of the cartridge holding member 30.

  10 and 11 are configuration diagrams in the middle of the opening and closing cover 11 being opened. As shown in FIGS. 10 and 11, for example, when the opening / closing cover 11 is opened to replace the process cartridge 7, one end 71 a of the first link 71 is pulled by the opening / closing cover 11, so that the opening / closing cover 11 opens. Move to.

  On the other hand, the connecting portions 71b and 72b of the second link 72 with the first link 71 move in the opening direction of the opening / closing cover 11, so that the opening / closing cover 11 tends to be pulled in the opening direction. However, since the lock lever 82 prevents the cartridge holding member 30 from moving, the second link 72 rotates in the counterclockwise direction while the connecting portion 72a to the cartridge holding member 30 remains stationary. As a result, when the opening / closing cover 11 is slightly opened, the positions and postures of the cartridge holding member 30 and the process cartridge 7 remain held at the image forming position α (see FIG. 10).

  The image forming apparatus of the present embodiment opens the opening / closing cover 11 as described above, and further opens the opening / closing cover 11 to release the coupling 26 during the time until the cartridge holding member 30 starts moving. The movement of the second link 72 is used as an operating force for operating the connection / disconnection means 27.

  That is, as shown in FIG. 5, the rack 28 is moved horizontally by the operation in which the second link 72 rotates around the connection point 72 a with the cartridge holding member 30. As shown in FIGS. 3 and 4, the horizontally moving rack 28 is engaged with a gear train 29 connected to the connecting / disconnecting means 27, and the rotation of the gear train 29 is transmitted to the outer cam 27a of the connecting / disconnecting means. Then, the outer cam 27a rotates. An inner cam 27b is engaged with the outer cam 27a, and the inner cam 27b can move in the horizontal direction shown in FIGS. 3 and 4 by the rotation of the outer cam 27a. The inner cam 27b is engaged with a drive side coupling 26a urged by a compression spring 31.

  As a result, as shown in FIG. 4, from the state in which the driving side coupling 26a and the driven side coupling 26b are engaged, the opening / closing cover 11 is opened and the outer cam 27a is rotated to move the inner cam 27b to FIG. By moving in the right direction shown, the drive side coupling 26a is moved to the retracted position to release the coupling state.

  Therefore, in any case, such as when the power is turned off during the image forming operation, the coupling 26 can be released while the opening / closing cover 11 is opened, and the operation reliability of the opening / closing cover 11 can be guaranteed. it can.

  Further, when the opening / closing cover 11 is opened, the first link 71 is pulled by the opening / closing cover 11 and further moves in the direction of the opening / closing cover 11, and the second link 72 moves from the rotational movement toward the opening / closing cover 11. Change to move. When the second link 71 changes to move in the direction of the opening / closing cover 11, an acting force pulling the coupling portion 72 a with the cartridge holding member 30 works, and the cartridge holding member 30 opposes the drag force of the lock lever 82, and FIG. As shown in FIG.

  Then, as shown in FIG. 6, when the lock lever 82 is released and the opening / closing cover 11 is fully opened, the cartridge holding member 30 and the process cartridge 7 are held in the attachment / detachment position β protruding from the inside of the apparatus main body. The process cartridge 7 and the intermediate transfer belt unit 23 can be easily attached and detached.

  In the above-described embodiment, an example in which the intermediate transfer belt 5 is used as a rotating body arranged to face a plurality of photosensitive drums that are driven and transmitted by the coupling 26 is shown, but this is limited to the intermediate transfer belt. There is no need, and it may be another belt member such as a conveyance belt that adsorbs and conveys the recording medium. Therefore, the coupling device having the above-described configuration can be suitably used even for an apparatus that directly transfers an image from a photosensitive drum to a recording medium without performing intermediate transfer.

  In the above-described embodiment, the color image forming apparatus in which four process cartridges are mounted has been illustrated. However, the above-described coupling configuration does not use an intermediate transfer belt, and a single process cartridge is mounted to generate a monochrome image. Even a monochrome image forming apparatus to be formed can be suitably used.

  Furthermore, the above-described coupling configuration can be suitably used in an apparatus that performs drive transmission using a coupling configuration in addition to the image forming apparatus.

It is the figure which showed the range which a coupling can mesh | engage. It is the figure which showed the shape of the drive side and the to-be-driven side coupling. It is a figure of the coupling cutting state of a photoconductor drum. It is a figure of the coupling connection state of a photoconductor drum. FIG. 4 is a cross-sectional view showing a configuration of a link mechanism, a rack, and a gear train of a drive cutting / connecting unit and a cover for a photosensitive drum. It is sectional drawing which shows the state which the opening / closing cover has opened completely. It is sectional drawing which shows a state when an opening / closing cover is closed. It is the figure which showed the structure of the opening / closing cover, the cartridge holding member, and the link mechanism. FIG. 6 is a diagram illustrating a mechanism for holding a cartridge holding member at an image forming position. It is sectional drawing which shows the state which the opening-and-closing cover began to open. It is sectional drawing which shows a state just before an opening-and-closing cover opens and a cartridge holding member begins to move. 1 is a cross-sectional view illustrating a configuration of an entire image forming apparatus. It is sectional drawing which shows a prior art example.

Explanation of symbols

P: Recording medium T1: Primary transfer unit T2: Secondary transfer unit 1 ... Photoconductor drum 2 ... Charging device 3 ... Scanner unit 4 ... Development unit 5 ... Intermediate transfer belt 6 ... Photoconductor unit 7 ... Process cartridge 8 ... Fixing unit 9… discharge roller pair
10… discharge tray
11… Open / close cover
12… Primary transfer roller
13… Secondary transfer roller
14, 15, 16a, 16b ... Roller
17… Feed cassette
18… feed roller
19… Separation pad
20 ... Image forming device body
21… Registration roller pair
22… Conveyor belt
23… Belt unit
26… Coupling
26a ... Drive side coupling
26b Driven side coupling
27… Connect / disconnect means
27a… Outer cam
27b ... Inner cam
28… Rack
29… Gear train
30 ... Cartridge holding member
30a ... Locking part
31… Spring
70… center of rotation
71 ... 1st link
72 ... Second link
80… center of rotation
82… Lock lever
83… Spring
90… Abutting member

Claims (5)

The driving side coupling and the driven side coupling in the separated position move relative to each other in the rotation axis direction and move to the engageable position, and the driving side coupling rotates and engages with the driven side coupling. In the coupling device in which the rotational force is transmitted,
T1 represents the time required for the drive side coupling that is movable to the engageable position to rotate until it engages with the driven side coupling;
When the time required for the drive side coupling and the driven side coupling to move relative from the separated position to the engageable position is T2,
T1> T2
A coupling device having the following relationship: In an image forming apparatus in which a process cartridge having an image carrier is mounted on the apparatus body, and an image formed on the image carrier is transferred to a recording medium to form an image.
A drive side coupling provided in the apparatus body;
A driven side coupling for transmitting a driving force to a process cartridge mounted on the apparatus body;
Have
The driving side coupling and the driven side coupling move relative to each other in the direction of the rotation axis from the separated position, and the driving side coupling rotates and engages with the driven side coupling to transmit the rotational force. Is,
T1 represents the time required for the drive side coupling that is movable to the engageable position to rotate until it engages with the driven side coupling;
When the time required for the drive side coupling and the driven side coupling to move relative from the separated position to the engageable position is T2,
T1> T2
An image forming apparatus having the following relationship: In an image forming apparatus in which a plurality of process cartridges having an image carrier are mounted on an apparatus main body, and an image is formed by rotating a rotating body arranged to face the plurality of image carriers.
A drive side coupling provided in the apparatus body;
A process cartridge mounted on the apparatus main body and a driven side coupling for transmitting a driving force to the rotating body;
Have
The driving side coupling and the driven side coupling move relative to each other in the direction of the rotation axis from the separated position, and the driving side coupling rotates and engages with the driven side coupling to transmit the rotational force. Is to be
T1 represents the time required for the drive side coupling that is movable to the engageable position to rotate until it engages with the driven side coupling;
When the time required for the drive side coupling and the driven side coupling to move relative from the separated position to the engageable position is T2,
T1> T2
An image forming apparatus having the following relationship: The rotation until the drive side coupling that is movable to the engageable position engages with the driven side coupling is slower than the rotation speed of the drive side coupling during the image forming operation. The image forming apparatus according to claim 2, wherein the image forming apparatus is provided. 4. The image forming apparatus according to claim 3, wherein the plurality of process cartridges and the rotating body are driven by a single drive source.

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