JP4590275B2 - Driving device, developing device, process cartridge, and image forming apparatus - Google Patents

Description

  The present invention relates to various image forming apparatuses that record an image on a recording medium such as a recording paper or a card, such as a copying machine, a printer, a facsimile, or a complex machine thereof, and more specifically, a driving device and a developing device in the image forming apparatus. The present invention relates to a process cartridge.

  2. Description of the Related Art Conventionally, in this type of image forming apparatus, each developing cartridge is appropriately selected and moved so as to perform development with a developing cartridge appropriately selected from a plurality of developing cartridges, and the developing roller in the developing cartridge is imaged. There are known ones that come into contact with a carrier or can be separated while maintaining a minute interval.

  For example, Patent Document 1 discloses an image forming apparatus in which the tooth surface phases of a pair of apparatus main body side driving gears and a developing cartridge side driving input (driven) gear are matched.

JP 2001-83801 A

  By the way, in Patent Document 1, the developing cartridge is moved to the photosensitive member side as a latent image carrier during image formation by the driving tangential force of a pair of driving input gears provided at both ends of the developing cartridge. A configuration is described in which the developer carrying member provided so as to be rotatable can be contacted with or not contacted with the photosensitive member, and the non-image forming member is separated from the photosensitive member.

  In this prior art, in order to bring the developing unit into contact with or away from the photosensitive member, the drive is transmitted from the driving gear to the driven gear of the developing roller by clutch ON / OFF. In this case, when the clutch is turned on, the driving power is transmitted to the driven gear, and the developing roller comes into contact with the photosensitive member. When blurring occurs or vibration is transmitted to the writing system, the LD, mirror, lens, and the like vibrate, so that the laser written on the photosensitive member vibrates and shock jitter appears in the image.

  In addition, even in a configuration including an elastic member such as a damper in order to relieve a shock at the time of contact, it is very difficult to maintain a slight amount of biting between the photosensitive member and the developing roller, and the shock is absorbed. There is a problem that I can not finish.

  The present invention has been made by paying attention to the above-described circumstances, and an object of the present invention is to appear in an image by reducing a contact shock when the developing unit at the time of color image formation contacts the photoconductor. It is an object of the present invention to provide a driving device, a developing device, a process cartridge, and an image forming apparatus that can reduce shock jitter.

In order to solve the above-mentioned problems, the invention described in claim 1 includes: a developing roller that develops toner in contact with or in proximity to an image carrier; a driven unit that rotates coaxially with the developing roller; and a driven unit. A driving unit that rotates the driven unit by meshing; and a drive control unit that can control a rotation speed of the driving unit . The driving control unit uses a driven unit that rotates by driving the driving unit during development. When the developing roller is moved from the retracted position to the developing position and the developing roller is moved from the retracted position to the developing position, the rotational speed of the driving means is set to be lower than that during the developing operation by the drive control means , and the developing roller retracted position is set. The moving speed from the toner to the developing position is reduced.

  According to a second aspect of the present invention, in the first aspect of the present invention, the drive control means temporarily retracts the developing roller to the retracted position when not developing, and sets the developing roller to the developing position when not developing. And a mode for waiting, and in the case of continuously passing a single-color image, the developing roller is kept at the developing position during non-development.

  According to a third aspect of the present invention, in the first aspect of the present invention, the drive control means temporarily retracts the developing roller to the retracted position during non-development, and sets the developing roller to the developing position during non-development. And a mode for waiting, and in the case of continuously passing a single color image, the developing roller is moved to a retracted position during non-development.

  According to a fourth aspect of the present invention, there is provided a developing device including the driving device according to any one of the first to third aspects.

  The invention described in claim 5 is characterized in that the developing device described in claim 4 is detachable from the main body of the image forming apparatus.

  According to a sixth aspect of the present invention, there is provided a process cartridge in which the developing device according to the fifth aspect, an image carrier, and a charging means for charging the image carrier are integrally stored, and the image forming apparatus It is detachable from the main body.

  The invention described in claim 7 is an image forming apparatus for color images provided with at least four process cartridges described in claim 6.

  According to the present invention, the developing unit is brought into contact with the image carrier of the developing unit by reducing the moving speed from the retracted position separated from the image carrier to the developing position in contact with the image carrier during image formation. It is possible to relieve the shock, reduce vibrations to the primary transfer unit and the writing unit, and reduce shock jitter appearing in the image.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a color laser printer 1 provided with a developing device 2 according to the present invention. The color laser printer 1 includes a photoconductor unit 11, a charging unit 12, a writing unit 13, and a developing unit. A unit 14, an intermediate transfer unit 15, a paper feed unit 16, a paper transfer unit 17, a fixing unit 18, and a cleaning unit 19 are provided. Reference numeral 16A denotes a conveyance roller.

  The photosensitive member 11 uses a photosensitive belt 11A as an image carrier, and an organic photosensitive layer is formed on the surface of the photosensitive belt 11A. A charging unit 12, a developing unit 14, and a cleaning unit 19 are installed around the photoreceptor belt 11A. The charging unit 12 applies a high voltage to the photoreceptor belt 11A to apply a uniform potential.

  The writing unit 13 includes a laser (not shown), a polygon mirror 13A, an f / θ lens 13B, and a reflection mirror 13C. For example, a laser is operated in accordance with an image signal output from a computer and converted into each color. That is, from this laser, lasers corresponding to image signals of black (hereinafter abbreviated as B), cyan (hereinafter abbreviated as C), magenta (hereinafter abbreviated as M), and yellow (hereinafter abbreviated as Y). Light is emitted, and this laser light is incident on the photosensitive belt 11A via the polygon mirror 13A, the f / θ lens 13B, and the reflection mirror 13C, and light writing is performed, thereby forming an electrostatic latent image of each color. The

  The developing unit 14 includes four developing cartridges 21 that respectively store toner of each color that is charged by applying a charge opposite to the potential applied to the photosensitive belt 11A by the charging unit. . The developing cartridge 21 is provided with a developing roller 22, and the toner of each color is electrostatically attracted to the electrostatic latent image via the developing roller 22 to form a toner image.

  In the intermediate transfer portion 15, an intermediate transfer belt that is in contact with a part of the photoreceptor belt 11A is used. To this intermediate transfer belt, a toner image is transferred onto the intermediate transfer belt by applying a charge opposite to that of the toner of each color, and this transfer operation is performed for each color. A double image is formed.

  The paper transfer unit 17 transfers the color toner of the four-color superimposed image formed on the intermediate transfer belt to the transfer paper by applying a charge opposite to the toner to the transfer paper transported by the transport roller 16A. To do.

  The fixing unit 18 is provided with a thermal transfer roller, and melts and fixes the toner of each color carried on the transfer paper.

  Next, the operation of the laser printer according to this embodiment will be described. For example, a color image signal output from a computer is decomposed into image signals of respective colors by the writing unit 13. A laser is activated based on the image signals of the respective colors thus separated, and optical writing is performed according to the image of each color. That is, laser light is incident on each color of the photoreceptor belt 11A, and an electrostatic latent image is formed for each color.

  Next, when the writing area of the photosensitive belt 11A on which the electrostatic latent image is formed reaches the developing unit 14, four developing cartridges containing toners of four colors B, C, M, and Y, respectively. The developing cartridge 21 corresponding to the color in which the color toner is stored is advanced toward the photosensitive belt 11A by the contact / separation mechanism, and the developing roller 22 provided in the developing cartridge 21 is moved to the photosensitive belt 11A. Abut or close. As a result, the charged color toner accommodated in the developing cartridge 21 is attracted by the electrostatic force from the developing roller 22 toward the electrostatic latent image on the photosensitive belt 11A, and is adsorbed according to the electrostatic latent image to be colored toner. Visualized as an image.

  Each color toner image adsorbed to the photosensitive belt 11A by electrostatic force is transferred to an intermediate transfer belt 15 which is given a charge having a polarity opposite to that of the color toner and is in partial contact with the photosensitive belt 11A. Is done. Such a transfer operation is performed four times for each color, and the color toner image formed for each color is superimposed on the intermediate transfer belt to form a four-color superimposed image.

  On the other hand, the transfer paper fed one by one from the paper supply unit 16 and conveyed toward the paper transfer unit by the conveyance belt is given a charge opposite to that of the color toner. When passing, the color toner that forms the four-color superimposed image formed thereon is adsorbed and transferred by electrostatic force. In this manner, the color toner that forms the four-color superimposed image transferred to the transfer paper is melted and fixed by the fixing unit 18.

  Next, the developing device 2 according to the present invention will be specifically described. The developing device 2 according to the first embodiment is prepared in the same manner for each of the B, C, M, and Y color toners. That is, as shown in FIG. 2, the developing device 2 is provided with a developing cartridge 21 for each color in order to store each color toner, and the developing cartridge 21 is advanced and retracted toward the photosensitive belt 11A. A driving device 3 is provided.

  As shown in FIG. 3A, each of these developing cartridges 21 is constantly given an elastic force in a direction away from a photosensitive member (not shown) by a compression spring 23 provided between the housing 10 on the apparatus main body side. Has been. As a result, when the developing cartridge 21 is not normally developed, the developing cartridge 21 is retracted to a state where the developing cartridge 21 abuts on the stopper 24 provided in the casing 10 on the apparatus main body side by the elastic force of the compression spring 23. .

  These developing cartridges 21 incorporate a developing roller 22 for supplying color toner to the photoreceptor belt 11A, and this developing roller 22 is rotated by a drive motor 31 described later.

  The driving device 3 shown in FIG. 2 causes the developing roller 22 on the side of the developing cartridge 21 containing the color toner to abut on the photosensitive belt 11A during the developing operation for supplying each color toner to the photosensitive belt 11A. While maintaining a very small distance (see FIG. 3B), the developing roller 22 is separated from the photosensitive belt 11A when the developing operation is not performed (see FIG. 3A).

  The drive device 3 of this embodiment includes a drive motor 31 attached to the housing 10 on the apparatus main body side, gears 32A to 32C that rotate by the drive force of the drive motor 31, and the rotation force of the gear 32C that drives the drive shaft 33. A clutch 32D that is connected to the drive shaft, a drive gear (drive means) 34 that is fixed to the drive shaft 33, a pair of left and right driven gears (driven means) 35 that mesh with the drive gear 34, and a development that is coaxial with the driven gear 35. The rotating shaft 38 to which the roller 22 is attached, a cap 36 provided at both ends of the rotating shaft 38, and a guide member 37 for guiding the moving operation of the cap 36 are configured. The rotation direction and the rotation speed of the drive motor 31 are controlled by the drive control means 30.

  The drive gear 34 is composed of a pair fixed to the left and right ends of the drive shaft 33, and the drive shaft 33 is rotatably attached to the housing 10 of the apparatus body via a bearing 10D.

  On the other hand, the driven gear 35 is attached to both sides of the developing cartridge 21 and is movable with respect to the casing 10 on the apparatus main body side, but the moving direction is regulated by the guide member 37.

  By the way, in the configuration described above, when the developing unit connects the clutch 32D from the standby position in FIG. 3A, driving is transmitted to the driven gear of the developing roller, and the photosensitive unit abutment position in FIG. Although it moves, the control which relieves a contact shock is performed by making the moving speed of the developing unit low at this time.

  First, the control of the conventional developing drive motor 31 for a single color image will be described with reference to the timing chart shown in FIG. First, the rotation speed of the developing motor is raised to full speed rotation in the non-image forming area (at the start), and the image forming area (the area indicated by the oblique line) is when the rotation after α time has elapsed from the ON signal of the clutch 32D. Control at the timing of starting. As an operation of the developing unit, the movement starts when the clutch 32D is turned on, and reaches the photosensitive member contact position during the α time. The image forming area means a time zone in which the developing toner is transferred to the latent image on the photoreceptor.

  Next, a description will be given of the control between the sheets (area indicated by the broken line). The clutch 32D is turned off simultaneously with the end of the image forming area, and then the control is performed at the timing when the image forming area starts when the rotation after the interval of α is stabilized from the ON signal of the clutch 32D. At this time, the developing drive motor 31 continues to rotate at full speed. The operation is the same for a color image, and the interval between sheets in a single color only corresponds to the interval between other color images.

  Next, FIG. 5 shows the control of the developing drive motor 31 at the time of color image according to the present invention. The development drive motor 31 of the development drive source for each color is provided with four motors corresponding to each color. As shown in FIGS. 5A to 5D, images are formed in the order of the first color → second color → third color → fourth color, and a color image is formed. ), The rotational speed of the developing motor is raised to a low speed, and after a lapse of β hours from the ON signal of the clutch 32D, the speed is switched to the full speed. As an operation of the developing unit, the movement starts when the clutch 32D is turned on, and reaches the photosensitive member contact position during β time. The clutch 32D is turned off at the same time as the image forming area is finished, the motor is stopped, and then the same operation of the second sheet as the next print image (start up to low-speed rotation, and after β hours from the ON signal of the clutch 32D, full-speed rotation is performed. Switching) is repeated.

  Here, four motors corresponding to each color have been described, but the first color and the third color are driven by a single development drive motor 31 and the second color and the fourth color are driven by a single development drive motor 31. Even if a total of two development drive motors 31 are used, the same drive is possible in terms of timing.

  Next, the control of the developing drive motor 31 at the time of monochromatic image according to the present invention will be described with reference to timing charts shown in FIGS.

  During continuous operation of a single color image, the single development drive motor 31 is always operated. Further, the paper interval at that time differs in length between papers corresponding to the paper size length in the transport direction. For example, A3 vertical feed is set to double paper spacing with respect to A4 horizontal feed. The reason is that there is a switchback during double-sided conveyance.

  When the interval between the sheets is short, as shown in FIG. 6, the clutch 32D is not turned off even when the previous image formation area ends, and the connection is maintained and the image formation is continued to the next image formation area. If the paper interval is long, as shown in FIG. 7, the clutch 32D is turned off simultaneously with the end of the previous image formation area, the motor is stopped, and then the motor is stopped until it rotates at a low speed. After a period of time, the rotation is switched to full speed rotation, and control is performed at the timing when the image forming area starts when the rotation is stabilized.

  The reason for having these two modes is that when the interval between sheets is short as shown in FIG. 8, the clutch 32D is turned off simultaneously with the end of the previous image formation area, the motor is stopped, and then it is attempted to start up to low speed rotation. This is because the development drive motor 31 is connected to the low-speed rotation without falling.

  As described above, according to the present exemplary embodiment, the speed at which the developing unit moves from the position separated from the photoconductor during color image formation until it contacts the photoconductor is lower than that of the conventional photoconductor. It is possible to relieve the contact shock, reduce vibrations to the primary transfer unit and the writing unit, and reduce shock jitter appearing in the image.

  Further, in this embodiment, the developing roller is continuously developed on the photosensitive member even in the non-image portion in the case of a single color image that is continuously operated by the same driving source, so that the photosensitive member of the developing unit is not reduced without reducing the image forming speed. It is possible to relieve contact shock.

  In this embodiment, in the case of a monochrome image in which the same drive source is continuously operated, when the developing roller is moved away from the photosensitive member, the non-image portion reduces the moving speed of the developing unit to reduce the contact shock. Thus, it is possible to relieve the photoconductor contact shock of the developing unit. Further, since it is not necessary to rotate the developing roller in the non-image area, it is possible to prevent the life of the developing unit from being deteriorated.

  Further, in the present embodiment, in the single color image that is the continuous operation of the same drive source, the separation between the continuous operation and the separation operation mode is separated by the time during which the drive in the low speed mode is stable. It is possible to relieve the contact shock.

  Needless to say, the present invention is not limited to the above-described embodiment, and can be variously modified without departing from the scope of the invention. As shown in FIG. 9, when the developing roller 22 is in the retracted position, the drive gear 34 and the driven gear 35 are disengaged from each other, and the developing device 2 is in contact with the housing 10 on the apparatus main body side. It is removable.

  Since the developing device 2 is detachable from the main body of the image forming apparatus, maintenance and replacement in the developing device 2 are easy, and shock jitter generated at the time of impact during the contact / separation operation of the developing device 2 is reduced. Can do.

  FIG. 10 shows the configuration of the process cartridge 61. In FIG. 10, the image carrier cartridge 51 in which the cleaning means 55 for cleaning the surface of the photoconductor 53 and the charging means 57 are integrated, and the developing cartridge 21 are integrated as members related to image formation, and a process cartridge is obtained. 61 is constituted.

  The process cartridge 61 is detachable from the main body of the image forming apparatus, so that the process cartridge 61 can be easily maintained and replaced, and a shock jitter generated at the time of an impact during the contact / separation operation of the developing device 2 in the process cartridge 61. Can be reduced.

  FIG. 11 shows a tandem type image forming apparatus 70 on which four process cartridges 61 shown in FIG. 10 are mounted. The image forming apparatus 70 includes four photoconductors (image carriers) 53 in the apparatus main body, and magenta, cyan, yellow, and black toner images are formed on the photoconductors 53. It has become. A toner image is transferred from each photosensitive member 53 to an intermediate transfer member 71 disposed opposite to the photosensitive member 53, and is collectively transferred to a transfer sheet conveyed from a paper feeding device 75 at a secondary transfer position 73, and a fixing device 77. And the paper discharge device 79 are sequentially conveyed.

1 is a schematic configuration diagram of a color laser printer according to the present invention. It is a block diagram of the contact-and-separation mechanism of the image development apparatus used for the image development part of the color laser printer of FIG. (A) is explanatory drawing which shows the separation state of a developing cartridge and a developing roller, (b) is explanatory drawing which shows the contact or proximity | contact state to the photoreceptor of a developing cartridge and a developing roller. It is a timing chart which shows control of the conventional development drive motor at the time of a monochrome image. FIG. 4 is a timing chart showing the control of the developing drive motor in the case of a color image according to the present invention, wherein (a) is the first color, (b) is the second color, (c) is the third color, and (d) is the fourth color. 6 is a timing chart showing control of the development drive motor during monochrome image according to the present invention. 6 is a timing chart showing control of the development drive motor during monochrome image according to the present invention. It is a timing chart when the interval between sheets is short. It is sectional drawing which shows schematically the image development apparatus of the image forming apparatus which concerns on the modification of this invention. FIG. 6 is a cross-sectional view schematically showing a process cartridge of an image forming apparatus according to a modification of the present invention. It is sectional drawing which shows roughly the whole image forming apparatus which concerns on the modification of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Developing apparatus 3 Drive apparatus 11 Photoconductor (image carrier)
22 Developing roller 30 Drive control means 34 Drive gear (drive means)
35 Driven gear (driven means)
53 Photoconductor (image carrier)
61 process cartridge 70 image forming apparatus

Claims (7)

A developing roller for developing a toner in contact with or in proximity to the image bearing member, and a driven means for rotating a developing roller coaxially, and driving means for rotationally driving the driven unit by engagement between the driven means, rotation of the drive means Drive control means capable of controlling the speed, and the drive control means moves the developing roller from the retracted position to the developing position using a driven means that is rotated by driving of the driving means at the time of development. When moving to the developing position, the driving control means lowers the rotational speed of the driving means than during the developing operation, and lowers the moving speed of the developing roller from the retracted position to the developing position. .   The drive control means has a mode in which the developing roller is temporarily retracted to the retracted position during non-development and a mode in which the developing roller is kept in the developing position during non-development. The driving device according to claim 1, wherein the roller is kept waiting at the developing position.   The drive control means has a mode in which the developing roller is temporarily retracted to the retracted position during non-development and a mode in which the developing roller is kept in the developing position during non-development. The drive device according to claim 1, wherein the roller is moved to a retracted position.   A developing device comprising the driving device according to claim 1.   5. The developing device according to claim 4, wherein the developing device is detachable from the main body of the image forming apparatus.   6. A process cartridge comprising: the developing device according to claim 5; an image carrier; and a charging unit that charges the image carrier. The process cartridge is detachable from the image forming apparatus main body. .   An image forming apparatus for color images, comprising at least four process cartridges according to claim 6.

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