JP4955498B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to a developing device and an image forming apparatus used in an electrophotographic system such as a copying machine, a printer, and a facsimile.

  In an electrophotographic image forming apparatus that develops an electrostatic latent image formed on a photoreceptor using a powder developer, the developer is transported to a development area using a developing device. In the developing device, a developer regulating member is provided in order to make the amount of the developer conveyed to the developing area uniform.

  This developer description member is deformed depending on how the developer transport pressure is applied because the developer pressure to which the developer in the developing device is sequentially supplied is applied, and the developer amount cannot be specified. There is.

  Therefore, Patent Document 1 proposes a configuration in which the deformation amount due to the developer pressure is reduced by forming the layer thickness regulating member from a metal sheet metal and adding a drawing shape.

  In addition, the developing device has an opening at a portion facing the photoconductor, and the developing member disposed inside the device faces the photoconductor. However, since the developer leaks from the opening due to the structure, a seal member is used. Provided.

  For example, Patent Document 2 proposes a configuration in which an inlet seal and a side seal are attached to one member and set in a developing device for the purpose of improving the stickability of the seal.

Japanese Patent Laid-Open No. 2002-14886 JP 09-319215 A

In Patent Document 1, a diaphragm shape is formed on the layer thickness regulating member to improve strength and suppress deformation due to the developer pressure. However, an increase in parts cost is inevitable.
An object of the present invention is to propose a developing device and an image forming apparatus that can secure a sealing property while preventing deformation of a layer thickness regulating member due to developer pressure at low cost.

  In order to achieve the above object, a first aspect of the present invention is a developer that is rotatably supported by a developer container that contains a developer and supplies the developer to a development region facing an image carrier on which a latent image is formed. A carrier, a plate-like layer thickness regulating member that extends in the rotation axis direction of the developer carrier and regulates the thickness of the developer layer on the surface of the developer carrier, and the free end abuts the image carrier. The seal member disposed so as to prevent the developer from dropping from the gap between the image carrier and the developer carrier, and the base end side of the seal member are fixed, and the layer thickness regulating member and the developing container are sandwiched It has the fixing member installed in this way.

  According to a second aspect of the present invention, in the developing device according to the first aspect, the fixing member extends in the direction of the rotation axis of the developer carrying member, and the center portion in the longitudinal direction has a layer thickness compared to the end portion. It is characterized by projecting toward the regulating member side.

  According to a third aspect of the present invention, in the developing device according to the first or second aspect, the fixing member is made of a resin having an antistatic property, and the fourth aspect of the present invention is the first or second aspect. In this developing apparatus, the fixing member is formed of a nonmagnetic metal material.

  According to a fifth aspect of the present invention, there is provided an image carrier, a charging unit for charging the surface of the image carrier, a cleaning unit for removing the developer remaining on the surface of the image carrier, and a developer on the surface of the image carrier. And a developing device according to any one of claims 1 to 4 as the developing device.

  According to a sixth aspect of the present invention, in the process cartridge according to the fifth aspect, the image carrier and the developer carrier are arranged at a predetermined interval, and an opening through which exposure light to the image carrier passes is provided. The region of the opening is formed so that the fixing member can be detached from the opening.

  An image forming apparatus according to claim 7 is provided with the developing device according to any one of claims 1 to 4, and the image forming apparatus according to claim 8 is a process according to claim 5 or 6. According to a ninth aspect of the present invention, in the image forming apparatus according to the seventh or eighth aspect, a spherical toner is used as the developer.

  According to the present invention, since the base end side of the seal member is fixed and the fixing member is installed so as to sandwich the layer thickness regulating member and the developing container, the fixing member suppresses the bending of the layer thickness regulating member. As a result, the gap between the layer thickness regulating member and the developer carrier is constant over the longitudinal direction, and a constant amount of developer can always be conveyed to the image carrier. In addition, since the fixing member for fixing the inlet seal has a function of suppressing the bending of the layer thickness regulating member due to the agent pressure, it is possible to realize a cheaper configuration than achieving each effect by using separate parts.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a color printer as an image forming apparatus to which the present invention is applied. The image forming apparatus is not limited to a printer, and may be a copying machine, a facsimile machine, a multifunction machine, or the like using an electrophotographic system. The configuration and operation of the entire image forming apparatus will be described with reference to FIGS. The present invention can be applied not to a color image forming apparatus but also to an image forming apparatus using a single color developer.

  The color printer 1 shown in FIG. 1 is a so-called color laser printer, and a toner container housing portion 31 formed above the image forming apparatus main body 100 has four colors corresponding to yellow, magenta, cyan, and black. Two toner containers 32Y, 32M, 32C, and 32K are detachably (replaceable).

  An intermediate transfer unit 15 is disposed below the toner container housing 31. The intermediate transfer unit 15 includes an intermediate transfer belt 8 serving as an intermediate transfer member that is stretched over a plurality of roller members. Below the intermediate transfer belt 8, image forming portions 6Y, 6M, 6C, and 6K, which are process units corresponding to yellow, magenta, cyan, and black, face the intermediate transfer belt 8 and are juxtaposed with the intermediate transfer belt 8. Has been. Below the image forming units 6Y, 6M, 6C, and 6K, an exposure device 7 is disposed, and a plurality of paper feeding units 26 and 26 are disposed below the exposure device 7. Above the toner container accommodating portion 31, a stack portion 30 on which a transfer material P such as printed transfer paper is discharged and stacked is formed and disposed in the image forming apparatus main body 100.

  Next, the configuration of the image forming unit will be described on behalf of the configuration of the image forming unit 6Y corresponding to yellow. The image forming unit 6Y includes an image carrier 1Y composed of a photosensitive drum and a photoreceptor belt, a charging unit (charging unit) 4Y disposed around the image carrier 1Y, a developing device 5Y (developing unit), a cleaning unit. This is a well-known configuration including means (cleaning unit) 2Y, static elimination unit (static elimination unit) not shown. Then, an electrophotographic image forming process (charging process, exposure process, developing process, transfer process, cleaning process) is performed on the image carrier 1Y to form an image of yellow toner on the image carrier 1Y. become.

  The other three image forming units 6M, 6C, and 6K are also different from the image forming unit 6Y corresponding to yellow except that the color of the toner constituting the developer used differs from the position facing the intermediate transfer belt 8. The configuration is almost the same, and an image corresponding to each toner color is formed. Hereinafter, description of the other three image forming units 6M, 6C, and 6K will be omitted as appropriate, and only the image forming unit 6Y corresponding to yellow will be described.

As shown in FIG. 2, the image carrier 1Y is rotationally driven in a clockwise direction in FIG. 2 by a drive motor (not shown). Then, the surface of the image carrier 1Y is uniformly charged at the position of the charging unit 4Y (charging process). Thereafter, the surface of the image carrier 1Y reaches the irradiation position of the laser beam L emitted from the exposure device 7 shown in FIG. 1, and an electrostatic latent image corresponding to yellow is formed by exposure scanning at this position. (Exposure process.)
Thereafter, the surface of the image carrier 1Y reaches a position facing the developing device 5Y serving as a development area, and the electrostatic latent image is developed at this position to form a yellow toner image (development process). The surface of the image carrier 1Y reaches a position facing the intermediate transfer belt 8 and the first transfer bias roller 9Y, and the toner image on the image carrier 1Y is transferred onto the intermediate transfer belt 8 at the primary transfer position. (Primary transfer step). At this time, since a small amount of untransferred toner remains on the image carrier 1Y, the surface of the image carrier 1Y reaches a position facing the cleaning unit 2Y, and remains on the image carrier 1Y at this position. The transferred untransferred toner is mechanically collected by the cleaning blade 2a (cleaning step). The surface of the image carrier 1Y reaches a position facing an unillustrated neutralization unit, and the residual potential on the image carrier 1Y is removed at this position. In this way, a series of image forming processes performed on the image carrier 1Y is completed.

  The image forming process described above is performed in the other image forming units 6M, 6C, and 6K similarly to the yellow image forming unit 6Y. That is, the laser beam L based on the image information is emitted from the exposure unit 7 disposed below the image forming unit onto the image carriers of the image forming units 6M, 6C, and 6K. Specifically, the exposure unit 7 emits a laser beam L from a light source and scans the laser beam L with a polygon mirror that is rotationally driven, and then on the image carrier of each imaging unit via a plurality of optical elements. Irradiate. Thereafter, the toner images of the respective colors formed on the respective image carriers through the development process are transferred onto the intermediate transfer belt 8 in an overlapping manner. In this way, a color image is formed on the intermediate transfer belt 8.

  As shown in FIG. 1, the intermediate transfer unit 15 includes an intermediate transfer belt 8, four primary transfer bias rollers 9Y, 9M, 9C, and 9K, a secondary transfer backup roller 12, a cleaning backup roller 13, a tension roller 14, and an intermediate transfer unit. The transfer cleaning unit 10 and the like are included. The intermediate transfer belt 8 is stretched and supported by the three rollers 12 to 14 and is endlessly moved counterclockwise in FIG.

  The four primary transfer bias rollers 9Y, 9M, 9C, and 9K sandwich the intermediate transfer belt 8 with the image carriers 1Y, 1M, 1C, and 1K to form primary transfer nips. A transfer bias opposite to the polarity of the toner is applied to the primary transfer bias rollers 9Y, 9M, 9C, and 9K.

  The intermediate transfer belt 8 travels counterclockwise and sequentially passes through the primary transfer nips of the primary transfer bias rollers 9Y, 9M, 9C, and 9K, so that the intermediate transfer belt 8 moves over the image carriers 1Y, 1M, 1C, and 1K. Are transferred onto the intermediate transfer belt 8 so as to be primarily transferred.

  Thereafter, the intermediate transfer belt 8 on which the toner images of the respective colors are transferred in a superimposed manner reaches a position facing the secondary transfer roller 19. At this position, the secondary transfer backup roller 12 sandwiches the intermediate transfer belt 8 with the secondary transfer roller 19 to form a secondary transfer nip. The four color toner images formed on the intermediate transfer belt 8 are transferred onto the transfer material P conveyed to the position of the secondary transfer nip. At this time, the untransferred toner that has not been transferred to the transfer material P remains on the intermediate transfer belt 8. Thereafter, the intermediate transfer belt 8 reaches the position of the intermediate transfer cleaning unit 10, and untransferred toner on the intermediate transfer belt 8 is collected at this position. Thus, a series of transfer processes performed on the intermediate transfer belt 8 is completed.

  The transfer material P transported to the position of the secondary transfer nip is transported from a paper feed unit 26 disposed below the image forming apparatus main body 100 via a paper feed roller 27, a registration roller pair 28, and the like. It is a thing.

  More specifically, a plurality of transfer materials P are stored in each sheet feeding unit 26 in a stacked manner. When the paper feed roller 27 is rotated in the counterclockwise direction in FIG. 1, the uppermost transfer material P is fed between the rollers of the registration roller pair 28. The transfer material P conveyed to the registration roller pair 28 is temporarily stopped at the position of the roller nip of the registration roller pair 28 that has stopped rotating. Then, the registration roller pair 28 is rotationally driven in synchronization with the color image on the intermediate transfer belt 8, and the transfer material P is conveyed toward the secondary transfer nip. Thus, a desired color image is transferred onto the transfer material P.

  The transfer material P on which the color image is transferred at the position of the secondary transfer nip is conveyed to the fixing unit 20. The color image transferred to the surface is fixed on the transfer material P by heat and pressure generated by a known fixing roller and pressure roller. The transfer material P on which the image has been fixed passes through the pair of paper discharge rollers 29 and is discharged to the outside of the apparatus, and is sequentially stacked on the stack unit 30 as an output image. Up to here, a series of image forming processes in the color image forming apparatus is completed.

Next, the configuration and operation of the developing device in the image forming unit will be described in more detail with reference to FIG. Here, the yellow developing device 5Y will be described as a representative.
The developing device 5Y includes a developer carrier 51Y that faces the image carrier 1Y, a layer thickness regulating member 52Y that faces the developer carrier 51Y, and two transport screws 55Y disposed in the developer accommodating portions 53Y and 54Y. Further, a density detection sensor 56Y for detecting the toner density in the developer is provided. In the developer accommodating portions 53Y and 54Y, a two-component developer G composed of a carrier and a toner is accommodated. The developer accommodating portion 54Y communicates with the toner receiving port 43Y through an opening 60Ya formed above the developer accommodating portion 54Y.

  The developer carrier 51Y is configured in a known roller shape such as a magnet fixed inside and a sleeve rotating around the magnet. The developer carrier 51Y is disposed in a casing 60 serving as a developer container for containing the developer and is rotatably supported, and supplies the developer to a development region facing the image carrier 1Y on which a latent image is formed. It is configured as follows. The image carrier 1Y and the developer carrier 51Y are arranged at a predetermined interval when mounted on the image forming unit 6Y.

  The thickness regulating member 52Y extends in the rotation axis direction of the developer carrier 51Y and regulates the thickness of the developer layer on the developer carrier surface 51Ya, and is constituted by a plate-like member. Between the layer thickness regulating member 52Y and the charging roller 4Y, an opening 160 through which the exposure light L to the image carrier 1Y passes is formed. Within the opening 160, the free end 157Ya has elasticity to abut against the surface of the image carrier 1Y so as to prevent the developer from dropping from the gap between the image carrier 1Y and the developer carrier 51Y. The base end 157Yb of the seal member 157Y is mounted and disposed on the fixing member 57Y.

  The fixing member 57Y is configured to be detachable from the casing 60 of the developing device 5Y included in the image forming unit 6Y with the seal member 157Y attached. As shown in FIG. 4, the fixing member 57Y extends in the rotation axis direction of the developer carrier 51Y indicated by the arrow X, and circular boss portions 158Ya and 158Yb are provided at both ends 57Ya and 57Yb, respectively. ing. The boss portions 158Ya and 158Yb are formed so as to be inserted into a groove (not shown) formed on the developing device 5Y side when being attached to and detached from the casing 60.

  The fixing member 57Y includes a mounting portion 57Yc to which the seal member 157Y is mounted, and a snap fit portion 57Yd that is formed integrally with the mounting portion 57Yc and that is disposed with a space YS1 from the mounting portion 57Yc. Yes. The snap fit portion 57Yd is a claw portion formed so as to be caught by the casing 60 when it is attached to the casing 60 of the developing device 5Y, and can be elastically deformed. The interval YS1 is a space into which both the casing 60 and the layer thickness regulating member 52Y attached and fixed thereto are inserted, and is formed so as to sandwich the casing 60 and the layer thickness regulating member 52Y. As shown in FIG. 5, the fixing member 57 </ b> Y is formed such that the central portion 51 </ b> Ye in the longitudinal direction protrudes to the layer thickness regulating member side 52 </ b> Y as compared with both ends 51 </ b> Ya and 51 </ b> Yb.

  The length of the seal member 157Y is set so that the free end 157Ya comes into contact with the surface of the image carrier 1Y when the fixing member 57Y is attached to the developing device 5Y. The opening 160 has a region that is large enough to allow the fixing member 57Y to which the seal member 157Y is attached to be attached and detached.

The developing device 5Y configured as described above operates as follows.
The sleeve of the developer carrier 51Y rotates in the direction of the arrow in FIG. The developer G carried on the developer carrier 51Y by the magnetic field formed by the magnet moves on the developer carrier 51Y as the sleeve rotates.

  Here, the developer G in the developing device 5Y is adjusted so that the ratio of toner in the developer (toner concentration) is within a predetermined range. Specifically, according to the toner consumption in the developing device 5Y, the toner stored in the toner container 32Y is supplied into the developer storage portion 54Y via a toner supply device (not shown). Thereafter, the toner replenished in the developer accommodating portion 54Y is circulated through the two developer accommodating portions 53Y and 54Y while being mixed and stirred together with the developer G by the two conveying screws 55Y and 55Y. The circulation direction is a direction perpendicular to the paper surface of FIG. The toner in the developer G is adsorbed to the carrier by frictional charging with the carrier and is carried on the developer carrier 51Y together with the carrier by the magnetic force formed on the developer carrier 51Y.

  The developer G carried on the developer carrier 51Y is conveyed in the direction of the arrow in FIG. 2 and reaches the position of the layer thickness regulating member 52Y. The developer G on the developer carrier 51Y is conveyed to a position (development region) facing the image carrier 1Y after the developer amount is made appropriate at this position. The toner is attracted to the latent image formed on the image carrier 1Y by the electric field formed in the development area. Thereafter, the developer G remaining on the developer carrier 51Y reaches the upper portion of the developer container 53Y as the sleeve rotates, and is detached from the developer carrier 51Y at this position.

  Next, mounting of the fixing member 57Y and the seal member 157Y will be described. As shown in FIG. 3, the fixing member 57Y detached from the casing 60 (developing device 5Y) is inserted through the opening 160 for exposure (in the direction of the arrow in the figure), and the bosses 158Ya and 158Yb at both ends thereof are placed in the casing. Set so as to fit in a groove (not shown) provided in 60. Then, as shown in FIG. 2, the snap fit portion 57Yd bites into the casing 60 by pushing it into the casing 60 as it is, and the assembling work of the developing device 5A is completed. The boss portions 158Ya and 158Yb and the groove are desirably arranged so that the casing 60 and the layer thickness regulating member 52Y are positioned in the interval YS1 when they are engaged and moved toward the inside of the casing 60. . Such a configuration is not only applied to the yellow developing device 5Y and the image forming unit 6Y, but is similarly applied to the developing device 5Y and the image forming unit 6Y of each color.

  In this way, the base end side 157b of the seal member 157Y is fixed to the fixing member 57Y installed so as to sandwich the layer thickness regulating member 52Y and the casing 60, and is attached to the casing 60. The bending of the thickness regulating member 52Y is suppressed, and the gap between the layer thickness regulating member 52Y and the developer carrier 51Y is constant over the longitudinal direction, so that a constant amount of developer is always conveyed to the image carrier 1Y. be able to. In addition, since the fixing member 57Y for fixing the seal member 157Y has a function of suppressing the bending of the layer thickness regulating member 52Y due to the agent pressure, it is less expensive than achieving the respective effects with conventional separate parts. Can be realized.

  In addition, since the central portion 57e of the fixing member 57Y protrudes toward the layer thickness regulating member 52Y, the deflection of the central portion of the layer thickness regulating member 52Y having the largest deflection due to the agent pressure can be more effectively suppressed.

  If each color fixing member is formed of a resin having antistatic properties, it is possible to prevent dust from adhering to the surface of the member due to charging, and a defect caused by obstructing the exposure light L to the image carrier 1Y. Images can be suppressed. When each color fixing member is formed of a nonmagnetic metal material, the strength is higher than that of a resin material or the like, and the effect of suppressing the bending of the layer thickness regulating member can be further enhanced.

  In this embodiment, each color process cartridge includes a seal member integrated with a fixing member, and a developing device that serves as a reinforcement structure for the layer thickness regulating member by attaching the fixing member to the casing. Exchange workability by the user is improved. In addition, since each seal member is mounted on the casing and the positional relationship with the image carrier is defined, the seal member mounting system is higher than when the seal member is attached and detached alone, and is unnecessary. It is also possible to eliminate the problem of scratching the surface of the image carrier due to various mounting operations.

  Each process cartridge has an opening area so that the fixing member can be attached and detached from the opening through which the exposure light to the image carrier passes. It is possible to eliminate the problem of scratching the surface of the image carrier. In addition, since the seal member can be mounted without disassembling the process cartridge after measuring the gap between the image carrier and the developer carrier in the assembly process, the measured values of the carrier and developer carrier can be guaranteed. It can be done reliably, leading to improved image quality.

  Since each layer thickness regulating member is not bent and a constant amount of developer is always conveyed to the image carrier, a good image can be output and the process cartridge system is used. Can be provided. When a spherical toner is used as the toner constituting the developer, the development state is improved, so that a high-quality image can be provided.

1 is an overall configuration diagram of an image forming apparatus according to an embodiment of the present invention. FIG. 3 is an enlarged view of a developing device and a process cartridge showing a mounting state of a seal member. FIG. 3 is an enlarged view of a developing device and a process cartridge showing a state before the seal member is mounted. It is a partially broken perspective view which shows the structure of the fixing member with which the sealing member was mounted | worn. It is a top view which shows the structure of a fixing member.

Explanation of symbols

1 (Y, M, C, K) Image carrier 2 (Y, M, C, K) Cleaning means 4 (Y, M, C, K) Charging means 5 (Y, M, C, K) Developing device 6 (Y, M, C, K) Process cartridge 51 (Y, M, C, K) Developer carrier 51 (Y, M, C, K) a Developer carrier 52 (Y, M, C, K) Layer thickness regulating member 57 (Y, M, C, K) Fixing member 57 (Y, M, C, K) e Center portion 57 (Y, M, C, K) b, c Both ends 60 Developer container 157 (Y, M, C, K) seal member 157 (Y, M, C, K) a free end 157 (Y, M, C, K) b base end 160 (Y, M, C, K) opening G developer L Exposure light

Claims (9)

A developer carrier that is rotatably supported by a developer container that contains the developer, and that supplies the developer to a development region facing the image carrier on which the latent image is formed;
A plate-like layer thickness regulating member that extends in the rotation axis direction of the developer carrying body and regulates the thickness of the developer layer on the surface of the developer carrying body;
A seal member disposed such that a free end abuts against the image carrier and the developer is prevented from dropping from a gap between the image carrier and the developer carrier;
A developing device, comprising: a fixing member fixed to a base end side of the seal member and installed so as to sandwich the layer thickness regulating member and the developing container.   The fixing member extends in a rotation axis direction of the developer carrying member, and a central portion in a longitudinal direction thereof protrudes toward the layer thickness regulating member as compared with an end portion. Item 2. The developing device according to Item 1.   The developing device according to claim 1, wherein the fixing member is formed of a resin having an antistatic property.   The developing device according to claim 1, wherein the fixing member is made of a nonmagnetic metal material. An image carrier, a charging unit that charges the surface of the image carrier, a cleaning unit that removes the developer remaining on the surface of the image carrier, and a developing device that supplies the developer to the surface of the image carrier And
A process cartridge comprising the developing device according to claim 1 as the developing device. The image carrier and the developer carrier are arranged at a predetermined interval,
An opening through which exposure light to the image carrier passes;
6. The process cartridge according to claim 5, wherein a region of the opening is formed so that the fixing member can be attached and detached from the opening.   An image forming apparatus comprising the developing device according to claim 1.   An image forming apparatus comprising the process cartridge according to claim 5.   9. The image forming apparatus according to claim 7, wherein a spherical toner is used as the developer.

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