JP4855742B2 - Developing device and image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, and a facsimile machine that develops an electrostatic latent image formed on an image carrier (photoreceptor) by an electrophotographic method, an electrostatic recording method, and the like to form a visible image. The present invention relates to a developing device and an image forming apparatus thereof.

It is equipped with a plurality of developing cartridges facing the photoconductor, and when developing an image, the developing cartridge is sequentially moved to the photoconductor side, and a developing roller rotatably provided in each developing cartridge is brought into contact with the photoconductor, or non-contact There is known a developing device configured to perform development in order to separate the developing cartridge from the photosensitive member for non-image formation.
In the image forming apparatus having the movable developing cartridge, the developer (toner) is scattered and leaked to the outside of the developing cartridge due to the inertia force when the developing cartridge moves and the impact when the developing cartridge stops moving. There is.
In order to prevent such inconvenience, for example, Patent Document 1 discloses that a forward movement force is generated by abutting the developing roller or the developing cartridge immediately before the developing roller comes into contact with the photosensitive member by an advance operation of the developing cartridge at the time of image formation. A configuration is described in which an elastic member for braking is provided to reduce the impact on the image carrier.
Patent Documents 2 and 3 describe a configuration in which scattered toner accommodating portions are provided in the longitudinal direction and the depth direction of the toner carrier and the toner layer regulating member.
JP 2001-83801 A Japanese Patent Laid-Open No. 5-53434 Japanese Patent Laid-Open No. 11-133736

The technique of Patent Document 1 cannot completely prevent leakage of the developer. Japanese Patent Application Laid-Open No. 2004-228561 describes a configuration in which the toner container is inclined toward the back side (anti-photosensitive member side). However, with respect to the movement of the toner when the developing cartridge is close (when moving to the developing position). The effect was insufficient. Further, a configuration is disclosed in which the toner accommodated in the toner accommodating portion is returned to the hopper. For example, toner that falls from the tip of the developing blade (developer layer regulating member) includes many toners having a low charge amount. The collection / reuse to the hopper causes problems such as image deterioration such as background stains, so that actual use is difficult.
In the shape of the scattered toner container described in Patent Document 3, when the amount of toner in the toner container increases, the toner cartridge gets over the convex part at the tip of the toner container when contacting the developing cartridge (when moving to the developing position). The toner inside the unit may be scattered outside the developing cartridge.
In addition, the scattering and leakage of toner from around the developing roller often occurs from the seals on both ends of the developing roller and the developing blade. (Developing Cartridge) In the case where there is no mechanism or configuration for moving in the longitudinal direction, the toner deposited on the end of the toner containing portion may leak out of the developing device from the end of the toner containing portion over time.
An object of the present invention is to provide a developing device that can reliably prevent the developer from scattering and leaking out of the developing cartridge.

In order to achieve the above object, according to the first aspect of the present invention, a plurality of developing cartridges are arranged to face the photosensitive member, and the developing cartridges are sequentially moved to the developing position at the time of developing, and are rotated in the case of the developing cartridge. a developing roller provided to freely moving performs contact or development in a non-contact state with the photosensitive member, the developing device to move the developing cartridge to the retracted position during the non-development, the lower portion of the opening provided in the casing of the developing cartridge A developer receiving portion for receiving the developer scattered and leaked from around the developing roller over the entire width in the longitudinal direction, and a rising shape portion for preventing developer leakage formed at the tip of the developer receiving portion on the photoreceptor side When a developer accommodating portion for accommodating the developer receiving portion of the developer that moves along with the movement of the retracted position from the developing position of the developing cartridge, said current Zoka When cartridge is moved from its retracted position to the developing position, the developer in the developer containing portion and a developer movement restricting portion for preventing the movement into the developer receiving portion, the rising shape And a developer receiving portion, a developer movement restricting portion, and a developer accommodating portion .
According to a second aspect of the present invention, in the developing device according to the first aspect, the developer leakage preventing member whose tip contacts with a pressing force that does not affect the developer layer on the developing roller or in the vicinity of the developing roller. It is provided in the rising shape portion .
According to a third aspect of the invention, and characterized in that the developing apparatus according to claim 1 or 2, wherein both longitudinal ends of the developer receiving portion, the inclined portion inclined downwardly toward the center is formed To do.
The invention of claim 4, wherein the image forming apparatus equipped with a developing device according to any one of claims 1 to 3, feature.

  According to the present invention, a plurality of developing cartridges are provided facing the photosensitive member side, the developing cartridges are sequentially moved to the developing position at the time of image formation, and a developing roller provided rotatably in the developing cartridge is used as the photosensitive member. In a developing device that performs contact or non-contact development and moves the developing cartridge to the retracted position for non-image formation, the developing cartridge is scattered from the periphery of the developing roller to the lower part of the developing roller over the entire width in the longitudinal direction. A developer receiving portion that receives the leaked developer, a developer receiving portion that moves and stores the developer received in the developer receiving portion by moving the developer cartridge from the developing position to the retracted position, and further developing. Provided with a developer movement restricting portion that prevents the developer in the developer accommodating portion from moving to the developer receiving portion when the cartridge moves from the retracted position to the developing position. Since, scattering of the developer to the outside of the developer cartridge, it is possible to reliably prevent leakage.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a configuration diagram of a color laser printer as an image forming apparatus according to an embodiment of the present invention. The printer 1 includes a photoconductor 11, a charging device 12, a writing device 13, a developing device 14, an intermediate transfer belt 15, a paper feeding device 16, a transfer device 17, a fixing device 18, a cleaning device 19, and the like.
As the photoreceptor 11 which is an image carrier, a belt-shaped photoreceptor having an organic photosensitive layer formed on the surface is used. The charging device 12, the developing device 14, and the cleaning device 19 are installed around the photoconductor 11.
The charging device 12 applies a high voltage to the photoconductor 11 to apply a uniform potential to the surface of the photoconductor.
The writing device 13 includes a laser (not shown), a polygon mirror 13A, an f / θ lens 13B, a reflection mirror 13C, and the like. Laser beams 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) are emitted from the laser. Is done. This laser light is incident on the photosensitive member 11 through the polygon mirror 13A, the f / θ lens 13B, and the reflection mirror 13C, and optical writing is performed. Thereby, an electrostatic latent image of each color is formed on the surface of the photoconductor 11.
The developing device 14 includes four developing cartridges 21 in which toner of each color charged with a charge having a polarity opposite to that of the potential applied by the charging device 12 is individually stored in the photosensitive member 11. Yes. Since each developing cartridge 21 has the same configuration, FIG. 2 shows one of the developing cartridges 21.
Each developing cartridge 21 is provided with a developing roller 22 as shown in FIG. Each color toner is electrostatically attracted to the electrostatic latent image on the surface of the photoconductor 11 via the developing roller 22 of each developing cartridge 21, and a toner image of each color is sequentially formed on the surface of the photoconductor 11.
The intermediate transfer belt 15 is in contact with a part of the surface of the photoconductor 11. A charge having a polarity opposite to that of the toner of each color is applied to the intermediate transfer belt 15. As a result, the toner images of the respective colors formed on the surface of the photoconductor 11 are sequentially superimposed and transferred onto the intermediate transfer belt 15, and four color images are formed on the intermediate transfer belt 15.
The color image formed on the intermediate transfer belt 15 is transported from the paper feeding device 16 by a transport roller, and is transferred by the transfer device 17 onto a transfer sheet to which a charge having a polarity opposite to that of the toner is applied. The transfer paper onto which the color image has been transferred is discharged from the printer body after the toner is melted and fixed by the fixing device 18.

Next, the driving device for the developing cartridge 21 of the developing device 14 will be described. This drive device is prepared in the same manner for each developing cartridge 21 containing B, C, M, and Y color toners. As shown in FIG. 2, the driving device of the developing device 14 includes an approach / separation mechanism 3 that advances and retracts the developing cartridge 21 toward and from the photosensitive member 11.
As shown in FIGS. 2 and 3A, each developing cartridge 21 is constantly given an elastic force in a direction away from the photoconductor 11 by a compression spring 23 provided between the developing cartridge 21 and the housing 10 on the apparatus main body side. Has been. As a result, the developing cartridge 21 is normally retracted to abut against the stopper 24 provided on the housing 10 on the apparatus main body side by the elastic force of the compression spring 23 when development is not normally performed. Each developing cartridge 21 is detachable from the housing 10 on the apparatus main body side. These developing cartridges 21 incorporate a developing roller 22 for supplying color toner to the photoreceptor 11. The developing roller 22 is rotated by a drive motor 31.
The contact / separation mechanism 3 serving as the driving device abuts the developing roller 22 on the side of the developing cartridge 21 containing the color toner to the photosensitive member 11 during the developing operation for supplying each color toner to the photosensitive member 11 or a minute interval. Are held apart (see the solid line in FIG. 4). When the developing operation is not performed, the developing roller 22 is separated from the photosensitive member 11 (see the chain line in FIG. 4).
The contact / separation mechanism 3 includes a drive motor 31 attached to the housing 10 on the apparatus main body side, and gears 32A and 32B that are rotated by the drive force of the drive motor 31. Further, a clutch 32D that cuts and connects the rotational force of the gear 32B to the drive shaft 33, a drive gear 34 fixed to the drive shaft 33, and a pair of left and right driven gears 35 that mesh with the drive gear 34 are provided. Further, the rotating shaft 38 on which the developing roller 22 is mounted coaxially with the driven gear 35, the caps 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 provided. .

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.
The driven gear 35 is attached to both sides of the developing cartridge 21 and is movable with respect to the housing 10 on the apparatus main body side. The moving direction of the driven gear 35 is regulated by the guide member 37. Further, as shown in FIG. 4, the cap 36 is constituted by a substantially disk-shaped member having a predetermined radius provided at both ends of a rotating shaft 38 coaxial with the driven gear 35 and the developing roller 22.
On the other hand, as shown in FIG. 4, the guide member 37 has a shape having a narrow-diameter portion 37 </ b> A whose diameter is narrowed toward the photoreceptor 11. When the cap 36 comes into contact with the narrow-diameter portion 37A of the guide member 37, the moving operation of the developing cartridge 21 is stopped.
As a result, the approaching operation is restricted so that the developing cartridge 21 and the developing roller 22 do not come too close to the photosensitive member 11 by a certain distance or more. The positions of the developing cartridge 21 and the developing roller 22 when the cap 36 is closest are the normal developing positions for the photosensitive member 11.
As described above, in the developing device 14, each developing cartridge is appropriately selected and moved, and the developing roller 22 of the developing cartridge 21 is brought into contact with or separated from the photosensitive member 11 by the contact / separation device 3. It is configured as follows.

Hereinafter, main parts of the developing device according to the present invention will be described.
FIGS. 5A to 5C are views showing how the developer moves in the case of the first embodiment in accordance with the operation of the developing cartridge in the developing device according to the embodiment of the present invention. The case 40 of the developing cartridge 21 has a function of receiving and storing the developer scattered and leaked from around the developing roller 22.
The case 40 extends over the entire width of the developing cartridge opening in the longitudinal direction, and is provided with a developer receiving portion 40-1 below the developing roller 22, a developer movement restricting portion 40-2 rising in a substantially vertical direction, and a developer containing portion 40-. 3. The developer receiving portion 40-1 is located on the opening side (front side) which is the right direction in the figure, and the developer accommodating portion 40-3 is located on the back side (rear side) which is the left direction in the figure.
The developing cartridge 21 moves from the developing position shown in FIG. 5A to the retracted position shown in FIG. The developer received by the developer receiving portion 40-1 receives an inertial force in the process, passes through the developer layer restricting member (doctor roller) 41 and the gap of the case 40, and the developer movement restricting portion 40-2. Then, the developer is accommodated in the developer accommodating section 40-3. When this operation is repeated, the developer is accumulated in the developer container 40-3 as shown in (c).
For the next image forming operation, the developing cartridge 21 moves from the retracted position to the developing position. At that time, the developer in the developer accommodating portion 40-3 receives an inertial force on the front side of the developing cartridge (photoreceptor 11), but the developer receiving restricting portion 40-2 is caused by the developer movement restricting portion 40-2. -1 is prevented, and the developer is prevented from scattering and leaking outward from the developing cartridge opening.
As described above, even when the developing cartridge moving operation for image formation is repeated, as shown in FIG. 5C, the developer scattered and leaked from around the developing roller 22 is not contained in the developer containing portion 40. -3.
Note that a rising shape portion 40-4 for preventing leakage of the developer from the developer receiving portion 40-1 is provided at the tip of the developer receiving portion 40-1 on the photosensitive member 11 side. Further, a developer leakage preventing member 42 is provided in the rising shape portion 40-4. The tip of the developer leakage preventing member 42 is close to the developing roller 22 or is in contact with a contact pressure that does not affect the developer layer on the developing roller 22. By doing so, leakage of the developer can be prevented more reliably.
Further, by providing the developer receiving portion 40-1 with the inclined surface 40-1 ′ that descends toward the developer accommodating portion 40-3, the developer can be moved more smoothly and reliably. .
By the way, particularly in a developing device using a non-magnetic one-component developer, it is difficult to control leakage of the developer other than electrostatic force, and a developing roller, a developer layer thickness regulating member (blade, doctor roller), and developing Even if a sealing member straddling the cartridge case is disposed, a part of the sealing member may leak. When the developer at the end portion where the developer leakage is large accumulates in part over time, the developer in the developer accommodating portion 40-3 overflows, and the developer cartridge 21 is scattered and leaked to the outside of the developer cartridge. There is.

FIGS. 6A and 6B are configuration diagrams of a case according to the second embodiment, in which FIG. 6A is a perspective view, FIG. 6B is an A view of FIG. 6A, and FIG. The case 40 of the second embodiment is provided with inclined portions 40-1a inclined downward toward the center at both ends in the longitudinal direction of the developer receiving portion 40-1. When the developing cartridge 21 moves from the retracted position to the developing position, the developer dropped on the developer receiving portion 40-1 moves in the direction of arrow C shown in FIG. Housed in the center.
Thereby, it is possible to prevent the developer at the end portion where leakage is large from being partially accumulated over time, and to reliably prevent the developer from scattering and leaking to the outside due to the movement of the developing cartridge 21.

1 is a configuration diagram of a color laser printer as an image forming apparatus according to an embodiment of the present invention. It is a side view (perpendicular to the axial direction) of a general developing device. FIG. 3 is a diagram illustrating an operation of the developing cartridge illustrated in FIG. 2. FIG. 3 is a diagram showing a state where the developing cartridge shown in FIG. In the developing device according to the embodiment of the present invention, the developer moves in the case of the first example along with the operation of the developing cartridge. It is a block diagram of the case which concerns on a 2nd Example.

Explanation of symbols

14 Developing Device 21 Developing Cartridge 22 Developing Roller 40 Case 40-1 Developer Receiving Portion 40-2 Developer Movement Restricting Portion 40-3 Developer Housing Portion

Claims (4)

A plurality of developing cartridges are arranged facing the photoconductor, and during development, the developing cartridges are sequentially moved to the developing position, and a developing roller provided rotatably in the case of the developing cartridge is in contact with or not in contact with the photoconductor. In the developing device that performs development in the state, and moves the developing cartridge to the retracted position when not developing,
Over the longitudinal entire width at the bottom of the opening provided in the casing of the developer cartridge, formed at the tip of the photoreceptor side of a developer receiving portion for receiving the developer scattered or leaked from the developing roller around receives developer unit has been a rising shape portion for the developer leakage prevention, and the developer containing portion, wherein the moving with the developing position of the developing cartridge to move to the retracted position for accommodating the developer receiving portion of the developer, the current image cartridge when moves from its retracted position to the developing position, and a said developer movement restricting portion in which the developer in the developer accommodating portion is prevented from moving to the developer-receiving portion, and, the rising shape And a developer receiving portion, a developer movement restricting portion, and a developer containing portion . The developer rising prevention portion according to claim 1 , wherein a developer leakage preventing member is provided in the rising shape portion so that a tip thereof is brought into contact with a pressing force that does not affect the developer layer on the developing roller or in the vicinity of the developing roller . Development device. Wherein the longitudinal ends of the developer receiving portion, the developing device according to claim 1 or 2, characterized in that the inclined portion inclined downwardly toward the center is formed. Image forming apparatus characterized by mounting the developing device according to any one of claims 1 to 3.

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