JP2000227690A - Rotary developing device for image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotary developing device which smoothly transmits, in a coupled state, drive to a developing device and prevents, in an uncoupled state, vibration and swing of coupling components, and hence prevents the occurrence of noise. SOLUTION: In the developing device, when a joint drive shaft 36 moves in its axial direction by an equal to or more than a specific amount, an Oldham' s coupling 37 attached on the front end of the joint drive shaft 36 engages with a recess in the rear of a coupling gear 34 and a pawl 34a in the recess, thereby driving a supply roller 31 in a specific direction and at a specific rotating speed. The peripheral part of the Oldham's joint 37 is covered with an elastic sheet 41 and, in a coupled state, it is properly deformed to transmit drive force while absorbing the deviations of the shaft centers of the joint drive shaft 36 and supply roller 31. When they are brought into an uncoupled state, a coupling projection 37a is re-urged toward a rotation center by the elastic force of the elastic sheet 41, so that swing is restricted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary developing device for an image forming apparatus such as an electrophotographic copying machine, printer, facsimile or the like using two or more colors of toner.

[0002]

2. Description of the Related Art Each of latent images formed by exposing a color separation light image to a latent image carrier is developed with a toner of a complementary color of the color separation light. An image forming apparatus such as a full-color copying machine in which images are superimposed and transferred on the same paper, or images to be reproduced in different colors are separately exposed on a latent image carrier and developed with developers of different colors. There is known a multicolor image forming apparatus for transferring a plurality of obtained toner images in a superimposed manner on the same sheet. Although these image forming apparatuses require a plurality of developing units,
If each developing unit is configured separately and independently and arranged side by side around the latent image carrier, the size of the apparatus increases. Therefore, while providing a rotating body close to the latent image carrier, the rotating body supports a plurality of developing units at predetermined positions,
A rotary developing device has been developed in which each developing unit is sequentially rotated and conveyed so as to face a development area of the latent image carrier, thereby developing a latent image on the latent image carrier with each color toner. .

[0003] In such a rotary developing device, the drive transmission from the image forming apparatus main body to the developing device at the developing position is carried out smoothly to prevent the rotation unevenness, vibration, and poor engagement of the drive gear, and to form the drive gear. It is necessary to obtain a stable image free from abnormal images such as horizontal band-like pitch unevenness and density unevenness and horizontal stripe-like background soiling. For this reason, for example, an apparatus disclosed in JP-A-6-332285 employs an Oldham coupling as a drive transmission member.

In the apparatus disclosed in Japanese Patent Application Laid-Open No. Hei 6-332285, a joint having an Oldham-shaped coupling member attached to a tip end thereof is supported on a printer main body so as to be able to move in parallel in a joint axis direction, and the joint is operated during image forming operation. The coupling member is moved in the axial direction while being rotated, and the protrusion of the coupling member attached to the tip is fixed to the shaft of the developing roller (or supply roller) in the developing device in the axial direction. And the supply roller and the developing roller are driven in a predetermined direction and rotational speed.

However, in such a drive transmission mechanism configuration, when the coupling is not engaged, the movable-side coupling member moves freely within the movable range of the Oldham coupling, and thus constitutes Oldham. Noise may be generated from parts. In addition, since the concave portion of the coupling gear and the convex portion of the coupling member that engages with the claw portion in the concave portion are not located at the center, a problem may occur during insertion for engagement.

[0006] Also, Japanese Patent Application Laid-Open No. 6-332285 describes that
Although it is disclosed that an insertion guide is provided, if there is not enough space, it is not possible to provide sufficient guidance and poor engagement occurs, and if this is repeated, breakage of nails and abnormal wear occur. There is.

Further, in such a rotary type developing device, a driving device for positioning a developing roller for transporting a developer provided in each developing unit at a predetermined position in a developing area facing a latent image carrier at the time of development is provided. Although a motor and a gear device are used, there is a problem that gears are worn or noise is generated due to vibrations caused by the rotation. To the inventor's knowledge, conventionally, the solutions to these problems have been insufficient, and there has been a demand for a solution having a simple and simple configuration in consideration of cost and the like.

The present invention has been made in view of the above-mentioned conventional problems,
The drive transmission to the developing device can be performed smoothly, and the rotation unevenness and vibration of the drive gear, the engagement failure, etc. are prevented,
It is an object of the present invention to provide a rotary developing device capable of obtaining a stable image free from abnormal images such as horizontal band-like pitch unevenness (banding and jitter), density unevenness, and horizontal stripe-like background stain on a formed image.

[0009]

According to a first aspect of the present invention, there is provided a rotary developing device for an image forming apparatus, comprising: an electrostatic latent image formed on an electrostatic image carrier; A plurality of developing devices each having a roller member for adhering a powder developer to the developing device, and developing around a common rotation axis by rotating the developing devices around a common rotation axis. In a rotary type developing device for an image forming apparatus which performs development by moving to a position, a rotational drive transmitting device for rotating the developing device uses a coupling for absorbing eccentricity and deviation of an axis angle during rotation. A mechanism is provided, and the drive transmission mechanism has a means for restricting the movement of the coupling when the coupling is not connected.

According to a second aspect of the present invention, the coupling is an Oldham coupling, and the restricting means is an elastic member that covers an outer peripheral surface of the movable joint member.

According to a third aspect of the present invention, there is provided a developing device having a roller member for adhering a powder developer to an electrostatic latent image on an electrostatic image carrier to visualize the electrostatic latent image on the electrostatic image carrier. A plurality of the developing units are rotated around a common rotation axis to move to a developing position opposed to the electrostatic image bearing member to perform development by using an image forming apparatus. A drive source that rotationally drives the common rotation shaft, a motor, a worm gear attached to an output shaft of the motor, a worm wheel that meshes with the worm to convert the rotation axis direction to an orthogonal direction, and the worm wheel. And a coaxial spool gear, which are mounted on a common base body, and a buffer portion interposed between the base body and a member or the like located around the mounting portion in the image forming apparatus main body. Characterized by comprising attached to.

According to a fourth aspect of the present invention, the cushioning member is a rubber rubber damper having a right cylindrical shape, and the rubber damper is arranged at least on an upper side of the motor and a lower side of each gear.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic center cross-sectional view of a multicolor image forming apparatus that can employ an embodiment of a rotary developing device for an image forming apparatus according to the present invention. In the figure, reference numeral 1 denotes a belt-shaped photosensitive member which is driven to rotate in the direction of arrow A, and is supported around rollers 2 and 3. This photoreceptor 1 has a charging device 4
The surface is uniformly charged to a predetermined polarity. Then, a polygon mirror 5B driven to rotate by a motor 5A from a laser light source (not shown) by the scanning optical device 5,
An electrostatic latent image is formed on the surface of the photoconductor 1 charged with the laser light 5D corresponding to the write information for each color via optical components such as the fθ lens 5C and the mirror 5F. This latent image is developed and visualized by the cyan developing unit C, the magenta developing unit M, and the yellow developing unit Y provided in the black toner developing unit 7 or the multicolor developing unit 6. The multicolor developing device 6 is driven to rotate by a driving device (not shown), and moves a desired developing unit to a predetermined position to perform development.
The black toner developing unit 7 uses the cam 45 to
Approaching / separating from

In FIG. 1, reference numeral 10 denotes a belt-like intermediate transfer member which is rotatably supported by rollers 11 and 12 and which rotates in the direction of arrow B to contact the photoreceptor 1 to act on the photosensitive member 1. Receives the toner image on the photoreceptor 1.
In forming a full-color image, toner images of each color of black, yellow, magenta, and cyan are superimposed on the intermediate transfer body 10 and are collectively transferred to paper. The transfer to the paper is performed by the transfer roller 14.

The paper 17A is stored in a paper feeder (paper feed cassette).
17, the sheet is fed by the rotation of a sheet feeding roller 18, conveyed through a pair of conveying rollers 19, timed by a pair of registration rollers 20, and placed on a sheet 17A at a predetermined position on the intermediate transfer body 10. The toner image is transferred. Thereafter, the sheet 17A passes through the fixing device 50, receives the fixation of the toner image, and is discharged by the discharge roller pair 51 to the discharge stack unit 5.
2 are stacked with the image surface facing down, that is, in page order.

When the toner is transferred from the photosensitive member 1 to the intermediate transfer member 10, the toner remaining on the photosensitive member 1 is scraped off by a cleaning means (blade) 15A. On the other hand, the intermediate transfer member 10
The toner remaining on the intermediate transfer body 10 when the toner is transferred to the sheet 17 </ b> A is scraped off by the cleaning blade 16 </ b> A of the cleaning device 16. The cleaning unit 15 </ b> A of the photoconductor 1 always performs a cleaning operation while being in contact with the photoconductor 1.
Reference numeral 6A has a contact / separation mechanism for contacting the intermediate transfer member 10 after transferring the toner image onto the sheet 17A and scraping off the remaining toner, and controls the operation timing thereof.

In the drawing, reference numeral 21 denotes a charge removing lamp. The light from the charge removing lamp 21 makes the residual potential on the photoreceptor 1 normal after the cleaning process, and the process can proceed to the next image forming process.

FIG. 2 is a schematic center sectional view showing a state in which the front cover is opened and the process cartridge unit is to be taken out or to be mounted. In the figure, reference numeral 22 denotes a unitized process cartridge, which includes a photosensitive member 1, a charging device 4, an intermediate transfer belt 10, and a cleaning device 1.
6. The transport guide 23 and the like forming the paper transport path are integrally incorporated so that they can be replaced at the end of their service life.
In addition to the replacement of the process cartridge 22, the multi-color developing device 6, the black developing device 7, and the like are also replaced when their lifespan expires. The front frame 8 has a structure in which the front frame 8 can be pivotally opened around the support shaft 9A.

1 and 2, an electric equipment / control device E is accommodated, and a fan F is provided above the electric equipment / control device E. The fan F is provided to exhaust air to prevent an excessive rise in temperature in the machine. It has become. On the right side of the figure, another relatively small MF is provided. In the figure, the sheet feeding device MF is in a folded state, but is opened and used.

FIG. 3 is a cross-sectional view showing the drive connecting portions of the developing devices 6 and 7. FIG. 3A shows the drive connection unit 60 in a non-connected state, and FIG. 3B shows the drive connection unit 60 in a connected state. As shown in these drawings, a coupling gear 34 is attached to the end of the central shaft of the toner supply roller 31 that rotates in contact with the developing roller 30 so as to rotate integrally with the supply roller 31. The rear end of the coupling gear 34 has a concave shape, and a claw portion 34a is provided in the concave portion.

On the other hand, a joint drive shaft 36 which rotates substantially coaxially with the supply roller 31 and the coupling gear 34 at the developing position and is supported so as to be able to translate in the axial direction, and an Oldham joint 37 at the end thereof are provided in the apparatus main body. It is provided. As shown in FIG.
The swing plate 37b is sandwiched between the coupling convex portion 37a and the joint boss 37c, and is swingably fixed by a pin 37d. The outer circumference of the Oldham joint 37 is
Coupling protrusion 3 when uncovered by covering with elastic sheet 41
The backlash of 7a can be regulated. In the drawing, reference numeral 39 denotes a developing drive cover, and the coupling gear 34 faces to the outside from an opening provided in the developing drive cover 39, and can be engaged with the Oldham joint 37. In the figure, reference numeral 40 denotes a main body side plate, through which the joint drive shaft 36 passes.

The operation of the drive connecting portions of the developing devices 6 and 7 will be described. When the predetermined developing unit 6 (or 7) rotates (or moves horizontally) to a predetermined developing position facing the photoconductor 1 to develop the electrostatic latent image and stops,
The joint drive shaft 36 and the Oldham joint 37 are pushed out in the direction of arrow A in the figure by drive means (not shown).
When the joint drive shaft 36 moves in the direction of arrow A by a predetermined amount or more, the coupling convex portion 37a
It engages with the rear concave portion and the claw portion 34a in the concave portion, and drives the supply roller 31 in a predetermined direction and rotational speed. At this time, the elastic sheet 41 covering the outer peripheral portion of the Oldham joint 37 is appropriately deformed. In this state, the Oldham joint 37 transmits the driving force while absorbing the axial center deviation between the joint drive shaft 36 and the supply roller 31. A gear is formed on the body peripheral surface of the coupling gear 34, and the gear 33 and the toner conveying member 32 attached to the shaft of the developing roller 30 are formed.
The gear meshes with a gear 35 attached to the rear part, and transmits a driving force to the developing roller 30 and the toner conveying member 32.

A taper is formed on the outer periphery of the distal end of the coupling convex portion 37a so that the joint drive shaft 36
The coupling convex portion 37a can be more smoothly engaged with the concave portion at the end of the coupling gear 34 at the time of moving. Further, as described above, since the Oldham joint 37 moves while rotating, the coupling convex portion 37a and the claw portion 34a in the coupling gear 34 concave portion are securely engaged. When the predetermined developing operation at the developing position is completed, the drive shaft (not shown) drives the joint drive shaft 36 as shown in FIG.
Move in the direction of arrow B inside, the coupling convex portion 37a, the concave portion at the end of the coupling gear 34 and the claw portion 34a in the concave portion.
Is disengaged. At this time, Oldham Joint 3
The coupling convex portion 37a is again urged to the center of rotation by the elastic force of the elastic sheet 41 covering the outer peripheral portion of 7, and the swing is restricted.

FIG. 5 is a side view of a rotary driving device in another embodiment of the rotary developing device for an image forming apparatus according to the present invention, FIG. 6 is a front view thereof, and FIG. 7 is a plan view thereof. 6 in the figure
Reference numeral 0 denotes a gear for rotating the entire rotating body including the developing unit in the multicolor developing device 6. The driving device according to the present embodiment mainly includes a motor 61 such as a stepping motor or a pulse motor serving as a driving source, a worm 62 attached to the motor shaft, and meshing with the worm 62 to convert the direction of the rotating shaft into a direction orthogonal to the motor shaft. A worm wheel 63, a spool gear 64 formed coaxially with the worm wheel 63 for transmitting rotational driving force by meshing with the gear 60, and a base member 65 serving as a common base for mounting and fixing these. It is composed.

The base member 65 is made of, for example, a thick aluminum material having a relatively high rigidity and the like, and cushioning (more preferably, it is not limited to simple cushioning but also has a vibration-proof and vibration-damping function). There are also three rubber dampers 66. In the illustrated example, an upper central portion of the motor 61,
It is arranged below the worm 62 so as to be located on both sides of the spool gear 64. Of course, the number and position of these rubber dampers 66 are not limited to those in the illustrated example, and the material of the cushioning member is not limited to rubber.
It is preferable to arrange at least the upper side of the motor 61 and the lower side of each gear.

When attached to the main body of the image forming apparatus as such a unitized structure, the vibration generated by the motor 61 and gears is absorbed by the rubber damper 66 and is hardly transmitted to other constituent members. Further, since the meshing state of the gears is determined exactly at a predetermined position and state, the meshing state is improved without rattling, vibration and noise are less likely to occur, and thus, tooth wear and the like are reduced.

[0027]

According to the first and second aspects of the present invention, the rotary developing device for an image forming apparatus according to the present invention has the following features.
A rotation drive transmission device for rotating the developing device includes a drive transmission mechanism using a coupling that absorbs eccentricity and deviation of an axis angle during rotation, and the drive transmission mechanism regulates the movement of the coupling when not coupled. Since there is a means, noise due to rattling of the coupling during non-connection is not generated, and since the position of the coupling is regulated,
There is an effect that coupling insertion becomes easy.

According to the third and fourth aspects of the present invention, the rotary developing device for an image forming apparatus according to the present invention has a motor serving as a drive source, a worm gear attached to an output shaft of the motor, and a rotating shaft. A worm wheel that transforms in the orthogonal direction and a coaxial spool gear are mounted on a common base body, and these are unitized, and are interposed between members and the like located around the mounting portion in the image forming apparatus main body. Since the shock absorbing member is attached to the base body, vibration and noise caused by the rotation of the motor and gears are almost eliminated, and the meshing state of the gears is maintained in a good state, so that tooth wear is reduced. This has the effect of extending the life.

[Brief description of the drawings]

FIG. 1 is a schematic center cross-sectional view of a multicolor image forming apparatus that can employ an embodiment of a rotary developing device for an image forming apparatus according to the present invention.

FIG. 2 is a schematic center sectional view showing a state in which a front cover is opened and a process cartridge unit is to be taken out or attached in the apparatus of FIG. 1;

FIG. 3 is an enlarged sectional view showing a drive transmission mechanism in an embodiment of the rotary developing device for an image forming apparatus according to the present invention.

FIG. 4 is an exploded perspective view of the Oldham coupling shown in FIG. 3;

FIG. 5 is a side view of a rotary driving device in another embodiment of the rotary developing device for an image forming apparatus according to the present invention.

FIG. 6 is a front view of the same.

FIG. 7 is a plan view of the same.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoreceptor 2, 3 Roller 4 Charging device 5 Laser writing unit 6 Multicolor developing device 7 Black developing unit 8 Front frame 9 Main frame 10 Intermediate transfer belt 11, 12 Roller 13 Bias means 14 Transfer roller 15 Collection container 16 Cleaning device 17 Paper feeder 17A Paper 18 Paper feed roller 19 Transport roller pair 20 Registration roller pair 21 Static elimination lamp 22 Process cartridge unit 23 Transport guide 30 Developing roller 31 Supply roller 32 Toner transport member 33 Developing roller gear 34 Coupling gear 35 Toner transport gear 36 Joint Drive shaft 37 Oldham joint 37a Coupling projection 37b Swing plate 37c Joint boss 37d Pin 38 Developing side plate 39 Developing drive cover 40 Main body side plate 41 Elastic sheet 45 Cam 50 Fixing device 51 Paper discharge roller pair 52 Paper discharge stack part 60 Gear 61 Motor 62 Worm 63 Worm wheel 64 Spool gear 65 Base member 66 Rubber damper

Claims (4)

[Claims] A developing device having a roller member for adhering a powder developer to an electrostatic latent image on an electrostatic image carrier to visualize the developing device, wherein the developing device has a common rotating shaft In a rotary type developing device for an image forming apparatus that performs development by moving to a developing position facing the electrostatic image carrier by rotating around, a rotation drive transmitting device for rotating the developing device is provided with An image forming apparatus comprising: a drive transmission mechanism using a coupling that absorbs eccentricity and deviation of an axis angle; and the drive transmission mechanism includes a unit that restricts the movement of the coupling when the coupling is not connected. Rotary developing device. 2. The rotary developing device for an image forming apparatus according to claim 1, wherein said coupling is an Oldham coupling, and said regulating means is an elastic member covering an outer peripheral surface of a movable joint member. apparatus. 3. A developing device having a roller member for adhering a powder developer to an electrostatic latent image on an electrostatic image carrier and visualizing the electrostatic latent image, wherein the developing device has a common rotating shaft In a rotary developing device for an image forming apparatus that performs development by moving to a developing position opposed to the electrostatic image carrier by rotating around, a driving source that rotationally drives the common one rotation shaft includes: A motor, a worm gear attached to the output shaft of the motor, a worm wheel that meshes with the worm to convert the direction of the rotation axis into an orthogonal direction, and a spool gear that is coaxial with the worm wheel, and has a common base body. And a buffer member interposed between the base body and a member or the like located around the mounting portion in the main body of the image forming apparatus. Rotary developing device. 4. The rubber damper according to claim 1, wherein the shock-absorbing member is a straight cylindrical rubber damper, and the rubber damper is disposed at least on an upper side of the motor and a lower side of each of the gears.
Rotary developing device for an image forming apparatus.