JP6213822B2 - Developing device, and process cartridge and image forming apparatus including the same - Google Patents

Description

  The present invention relates to a developing device using a two-component developer including toner and a carrier, and a process cartridge and an image forming apparatus provided with the developing device.

  This type of developing device used in an image forming apparatus such as a printer, a facsimile machine, and a copying machine generally has two-component development along a developer supply / conveyance path extending in the direction of the rotation axis of the developer carrier along the developer carrier. The agent (hereinafter simply referred to as “developer”) is conveyed while stirring. Further, the developer transported in the developer supply transport path disposed below the developer carrier is supported on the surface of the rotating developer carrier, and the developer is supported by the rotation of the developer carrier. Supply to development area. Some conventional developing apparatuses employ a supply / recovery integrated system in which the developed developer that has consumed toner in the development region is separated from the developer carrying member and returned to the developer supply / conveyance path (Patent Documents 1 to 4). etc).

  In this integrated supply and recovery type developing device, the developed developer that has passed through the developing region on the surface of the developer carrying member and separated from the developer carrying member is agitated with the developer in the developer supply conveyance path. In some cases, the developer is immediately supplied to the developer carrier. This occurs when the developed developer separated from the developer carrier is mixed with the developer supplied to the developer carrier from the developer supply conveyance path. Since the developed developer consumes toner and has a low toner density, when it is supplied to the developer carrier, the developer having a reduced toner density is supplied to the development area, resulting in a reduction in image density. There is a risk.

As a method for preventing the developed developer from being immediately supplied to the developer carrier, a supply position where the developer is supplied from the developer supply conveyance path on the surface of the developer carrier, and the developed development. A method of separating the distance from the separation position where the developer is separated from the developer carrying member is conceivable.
In the configuration in which the developer carrying member rotates so as to move from the upper side to the lower side in the developing region, the downstream end of the developing region is positioned lower than the upper end of the developer carrying member. Further, the supply position where the developer is supplied from the developer supply conveyance path located below the developer carrier is also located below the developer carrier. Since it is necessary to set the separation position within a limited range between the downstream end of the development region at a position lower than the upper end of the developer carrier and the supply position located below the developer carrier, supply It is difficult to increase the distance between the position and the separation position.

  On the other hand, in Patent Documents 1 to 4, the developer carrying member rotates so that the surface moves from the lower side to the upper side in the development region, and the supply position on the surface of the developer carrying member is near the lower end of the developer carrying member. A developing device is described. In such a developing device, the surface of the developer carrying member that has moved from the lower side to the upper side in the developing region reaches a top end portion of the developer carrying member, and then reaches a wide range substantially over the entire portion that moves downward from the upper side. It is possible to set the separation position. For this reason, it is possible to increase the distance between the supply position and the separation position as compared with the configuration in which the developer carrying member rotates so as to move from the upper side to the lower side in the development region. It is possible to suppress the supply to the developer carrier.

  However, even if the developer carrying member rotates so that the surface of the developer carrying member moves from the lower side to the upper side in the developing region, the developer separated at the separated position more immediately can be carried on the developer. It is desired to suppress the supply to the body.

  The present invention has been made in view of the above problems, and the object thereof is as follows. That is, in the integrated supply and recovery method, a developing device that can effectively suppress the developer separated at the separation position from being immediately supplied to the developer carrying member, and a process cartridge and an image provided with the developing device. A forming apparatus is provided.

To achieve the above object, a first aspect of the invention, a developer bearing member that rotates to the surface moves from below to above in the developing area, the rotation of the developer carrying member below said developer carrying member disposed in the developer supply conveyance path extending in the axial direction, while conveying along a two-component developer containing toner and carrier of the developer supply conveyance path in the axial direction of said developer carrying member, said developing agent a two-component developer of the supply conveyance path includes a developer supply conveyance member supplying the surface of the developer carrying member, conveying the two-component developer carried on the surface of the developer carrying member to the developing region and, with developing the latent image with toner in the two-component developer in the developing region is adhered to the latent image on the latent image bearing member surface, the two-component developer having passed through the developing region developer carrying member It is separated from, and collected in the developer supply conveyance path development In location, a supply position in which the two-component developer from the developer supply conveyance path on the surface of said developer carrying member is supplied, the two-component developer having passed the developing region is separated from the developer carrier with respect to the surface between the spaced apart position, the opposed upper end portion over the entire axial direction of the developer carrying member, wherein the separated position and the supply position is opposed space within the developing device is opposed A developer having a partition plate that divides the space and has a lower end positioned above the developer supply conveyance path, and that contains the developer carrier, and a developer that supplies the developer carrier A developer container including the developer supply transport path, a frame forming a communication port for communicating the developer carrier storage unit and the developer container, and covering the communication port From one end to the other end in the rotation axis direction And a seal member that is folded back on the other end side and extends to the one end side, and the seal member is connected to the opening surface of the communication port from the one end side. by peeling off from the frame by pulling out in a direction parallel, in the configuration for releasing the seal of the communication port, and wherein Rukoto presser lifting the lower end of the partition plate is folded back portion of said seal member To do.

  According to the present invention, there is an excellent effect that the developer separated at the separation position can be effectively suppressed from being immediately supplied to the developer carrying member by the supply and recovery integrated system.

FIG. 3 is a cross-sectional explanatory view of the developing device according to the present embodiment. 1 is a schematic configuration diagram of a copier according to an embodiment. FIG. 2 is a schematic configuration diagram of an image forming unit. FIG. FIG. 3 is a top view schematically showing a developer circulation path in the developing device. Cross-sectional explanatory drawing of the developing device before starting use. FIG. The disassembled perspective view of a communicating port sealing member. The perspective view which shows the positional relationship of the frame attached to the developing lower case, and a magnetic board. FIG. 3 is a schematic cross-sectional view of a conventional supply / collection integrated developing device that does not include a partition plate. FIG. 6 is an explanatory diagram showing a developer path separated from a developing sleeve in a developing device including a partition plate. Sectional drawing of the image development apparatus when arrangement | positioning of a partition plate is not appropriate. Explanatory drawing of the position prescription | regulation of a partition plate front-end | tip part.

Hereinafter, an embodiment of a tandem color copying machine (hereinafter referred to as a copying machine 500) as an image forming apparatus to which the present invention is applied will be described.
FIG. 2 is a schematic configuration diagram of the copying machine 500. The copying machine 500 includes a document reading unit 4 and a document conveying unit 3 above a printer unit 100 as a main body unit of the image forming apparatus, and a sheet feeding unit 7 below the printer unit 100. The document conveying unit 3 conveys the document to the document reading unit 4, and the document reading unit 4 reads image information of the conveyed document. The paper supply unit 7 is a recording medium storage unit that stores transfer paper P that is a recording medium. The paper supply unit 7 stores a plurality of transfer papers P in a stacked manner, and the transfer paper P in the paper supply cassette 26. A paper feed roller 27 that feeds the printer unit 100. A one-dot chain line in FIG. 2 indicates a conveyance path of the transfer paper P in the copying machine 500.

  An upper portion of the printer unit 100 is a paper discharge tray 30 on which transfer paper P on which an output image is formed is stacked. The printer unit 100 includes four image forming units 6 (Y, M, C, K) as image forming units for forming toner images of respective colors (yellow, magenta, cyan, black), and an intermediate transfer unit 10. . Each image forming unit 6 (Y, M, C, K) includes a drum-shaped photoconductor 1 (Y, M, C, K) as an image carrier on which each color toner image is formed, and each photoconductor ( A developing device 5 (Y, M, C, K) for developing an electrostatic latent image formed on the surface of Y, M, C, K) is provided.

  The intermediate transfer unit 10 includes an intermediate transfer belt 8 stretched by a plurality of stretch rollers and a primary transfer bias roller 9 (Y, M, C, K). The intermediate transfer belt 8 is an intermediate transfer body on which the color toner images formed on the surface of each photoconductor 1 (Y, M, C, K) are transferred in a superimposed manner, and a color toner image is formed on the surface. . Further, the primary transfer bias roller 9 (Y, M, C, K) is applied with a transfer bias having a polarity opposite to the normal charging polarity of the toner, and on the surface of each photoreceptor 1 (Y, M, C, K). 1 is a primary transfer unit that transfers the toner image formed on the intermediate transfer belt 8 to the intermediate transfer belt 8. The image forming units 6 (Y, M, C, K) are arranged side by side so as to face the intermediate transfer belt 8 of the intermediate transfer unit 10.

  The printer unit 100 includes a secondary transfer bias roller 19 for transferring the color toner image on the intermediate transfer belt 8 onto the transfer paper P. Further, the printer unit 100 once stops the conveyance of the transfer paper P sent out by the paper feed roller 27 and adjusts the timing at which the intermediate transfer belt 8 and the secondary transfer bias roller 19 are conveyed to the opposing secondary transfer nip. A registration roller pair 28 is provided. Further, the printer unit 100 includes a fixing device 20 that fixes an unfixed toner image on the transfer paper P above the secondary transfer nip.

In addition, toner containers 11 (Y, M, C, and K) for each color are disposed below the paper discharge tray 30 in the printer unit 100 and above the intermediate transfer unit 10. Each color toner container 11 (Y, M, C, K) contains toner of each color (yellow, magenta, cyan, black) supplied to each developing device 5 (Y, M, C, K). Each color toner container 11 (Y, M, C, K) is detachably installed in the printer unit 100.
Further, below the four image forming units 6 (Y, M, C, K) in the printer unit 100, laser light L is irradiated on the surface of each photoconductor (Y, M, C, K). An exposure device 12 which is a latent image forming unit for forming an electrostatic latent image is provided.

FIG. 3 is an enlarged explanatory view of one of the four image forming units 6 (Y, M, C, K). The four image forming units 6 (Y, M, C, K) have substantially the same configuration and operation except for the color of the toner used in the image forming process. In the following description, symbols Y, M, C, and K indicating the above are omitted as appropriate.
FIG. 4 is a perspective explanatory view of the image forming unit 6. As shown in FIG. 4, the image forming unit 6 is a process cartridge that integrally supports the photosensitive member 1 and the developing device 5, and this process cartridge is detachable from the copying machine 500 main body. . This facilitates exchange of the developing device 5 in the main body of the copying machine 500 provided with the developing device 5, and improves the maintainability of the copying machine 500.

  The image forming unit 6 includes a photoconductor cleaning device 2 and a charging device 40 in addition to the developing device 5 around the photoconductor 1. In the image forming unit 6 of the present embodiment, the photoreceptor cleaning device 2 is configured to be cleaned by the cleaning blade 2a, and the charging device 40 is configured to be charged by the charging roller 4a. Further, the image forming unit 6 includes a charge eliminating unit (not shown) that removes the surface potential of the surface of the photoreceptor 1 after the transfer.

Hereinafter, an operation during normal color image formation in the copier 500 of the present embodiment will be described.
First, when a start button (not shown) is pressed in a state where the document is set on the document table of the document conveyance unit 3, the document is conveyed from the document table by the conveyance roller of the document conveyance unit 3, and the document reading unit 4. Placed on the contact glass. Then, the document reading unit 4 optically reads the image information of the document placed on the contact glass.

  Specifically, the document reading unit 4 scans an image of a document on the contact glass while irradiating light emitted from an illumination lamp. Then, the light reflected from the original is imaged on the color sensor via the mirror group and the lens. The color image information of the original is read for each color separation light of RGB (red, green, blue) by the color sensor, and then converted into an electrical image signal. Further, color conversion processing, color correction processing, spatial frequency correction processing, and the like are performed by the image processing unit based on the RGB color separation image signals to obtain yellow, magenta, cyan, and black color image information.

  Then, the image information of each color of yellow, magenta, cyan, and black is transmitted to the exposure device 12. The exposure device 12 emits laser light L based on the image information of each color toward the corresponding photoreceptor 1 (Y, M, C, K).

On the other hand, the four photoconductors 1 (Y, M, C, K) are rotated clockwise in FIGS. 2 and 3 by drive motors (not shown). First, the surface of the photoreceptor 1 (Y, M, C, K) is uniformly charged at a portion facing the charging roller 4a of the charging device 40 (charging process). As a result, a charged potential is formed on the surface of the photoreceptor 1 (Y, M, C, K). Thereafter, the surface of the charged photoreceptor 1 (Y, M, C, K) reaches a position where the laser beam L is irradiated.
In the exposure device 12, laser light L corresponding to the image signal is emitted from four light sources corresponding to each color. Each laser beam L passes through a different optical path for each color component of yellow, magenta, cyan, and black, and is irradiated on the surface of each photoreceptor 1 (Y, M, C, K) (exposure process).

  The laser beam L corresponding to the yellow component is applied to the surface of the first yellow photoreceptor 1Y from the left side of the drawing in FIG. At this time, the yellow component laser light L emitted based on the image signal from the exposure device 12 disposed below the yellow image forming unit 6Y is rotated at a high speed by a polygon mirror to rotate the rotation axis of the yellow photoconductor 1Y. Scanning is performed in the direction (main scanning direction). By irradiating the yellow photoconductor 1Y through the plurality of optical elements while being scanned with the laser light L in this manner, the surface of the yellow photoconductor 1Y after being charged by the charging device 40 is An electrostatic latent image corresponding to the yellow component is formed.

  Similarly, the laser beam L corresponding to the magenta component is irradiated onto the surface of the second magenta photoreceptor 1M from the left in FIG. 2, and an electrostatic latent image corresponding to the magenta component is formed. The cyan component laser light L is applied to the surface of the third cyan photoconductor 1C from the left in FIG. 2 to form an electrostatic latent image of the cyan component. The black component laser beam L is applied to the surface of the fourth black photoconductor 1K from the left in FIG. 2 to form a black component electrostatic latent image.

  Thereafter, the surface of the photoreceptor 1 (Y, M, C, K) on which the electrostatic latent images of the respective colors are formed reaches a position facing the developing device 5. Then, each color toner is supplied onto the surface of the photoreceptor 1 (Y, M, C, K) from the developing device 5 (Y, M, C, K) containing developer of each color toner and carrier, The latent image on the photoreceptor 1 (Y, M, C, K) is developed (development process). Thereby, a toner image of a corresponding color is formed on the surface of each photoreceptor 1 (Y, M, C, K).

  The surface of the photoreceptor 1 (Y, M, C, K) after passing through the developing area which is a portion facing the developing device 5 reaches a portion facing the intermediate transfer belt 8. Here, primary transfer bias rollers 9 (Y, M, C, and K) are installed at the opposing portions so as to contact the inner peripheral surface of the intermediate transfer belt 8. The photoconductor 1 (Y, M, C, K) and the primary transfer bias roller 9 (Y, M, C, K) face each other with the intermediate transfer belt 8 interposed therebetween, thereby forming a primary transfer nip. Then, the intermediate transfer belt 8 moves in the direction of the arrow in the figure (counterclockwise direction) and sequentially passes through the primary transfer nip of each primary transfer bias roller 9 (Y, M, C, K). At this primary transfer nip, the toner images of the respective colors formed on the respective photoreceptors 1 (Y, M, C, K) are sequentially transferred onto the intermediate transfer belt 8 (primary transfer process). As a result, a color toner image is formed on the intermediate transfer belt 8.

A small amount of untransferred toner remains on the surface of the photoreceptor 1 after passing through the primary transfer nip. The surface of the photoconductor 1 after passing through the primary transfer nip reaches a position facing the photoconductor cleaning device 2. The untransferred toner remaining on the photoconductor 1 is scraped off by the cleaning blade 2a at a position facing the photoconductor cleaning device 2 and mechanically collected (photoconductor cleaning process).
The surface of the photoconductor 1 that has passed through the portion facing the photoconductor cleaning device 2 passes through a charge removal unit that is opposed to a charge removal unit (not shown), and the residual charges are removed. Thus, a series of image forming processes on the photoconductor 1 is completed. In preparation for the next image forming operation.

The color toner images on the four photoconductors 1 (Y, M, C, K) are transferred in an overlapping manner, and the intermediate transfer belt 8 carrying the color toner images moves on the surface counterclockwise in FIG. It reaches the secondary transfer nip which is a position facing the secondary transfer bias roller 19. In the secondary transfer nip, the intermediate transfer belt 8 is sandwiched between the secondary transfer bias roller 19 and one of the stretching rollers to form a secondary transfer nip.
On the other hand, when the paper feeding roller 27 of the paper feeding unit 7 is driven to rotate counterclockwise in FIG. 2, the uppermost transfer paper P among the transfer papers P stored in the paper feeding cassette 26 is fed. Sent. The transfer paper P fed by the paper feed roller 27 from the paper feed cassette 26 containing the transfer paper P is guided to the registration roller pair 28 after passing through the conveyance guide, hits the registration roller pair 28, and stops once. To do. The transfer paper P that has struck the registration roller pair 28 is rotated by the registration roller pair 28 in accordance with the timing at which the color toner image formed on the intermediate transfer belt 8 is directed to the secondary transfer nip. It is conveyed toward.
Then, the color toner image carried on the intermediate transfer belt 8 at the secondary transfer nip is transferred onto the transfer paper P (secondary transfer step).

  Transfer residual toner that has not been transferred to the transfer paper P remains on the surface of the intermediate transfer belt 8 that has passed through the secondary transfer nip. The surface of the intermediate transfer belt 8 that has passed through the secondary transfer nip reaches a portion facing an intermediate transfer belt cleaning device (not shown). At this facing portion, the transfer residual toner adhering to the intermediate transfer belt 8 is collected by an intermediate transfer belt cleaning device (not shown), and a series of transfer processes in the intermediate transfer belt 8 is completed.

The transfer paper P on which the color toner image is transferred at the secondary transfer nip is guided to the fixing device 20. In the fixing device 20, a color image is fixed on the transfer paper P by heat and pressure at a fixing nip formed by a fixing roller and a pressure roller (fixing step).
The transfer paper P that has passed through the fixing device 20 is discharged as an output image outside the printer unit 100 by the paper discharge roller pair 25 and stacked on the paper discharge tray 30 to complete a series of image forming processes.

FIG. 1 is a cross-sectional explanatory view of the developing device 5 of the present embodiment.
The developing device 5 includes a developing roller 50 including a magnet roller 55 as a magnetic field generating unit and a developing sleeve 51 as a developer carrier that rotates around the magnet roller 55. The developing roller 50 is provided in a developing roller accommodating portion 62 as a developer carrying member accommodating portion.
The developing sleeve 51 is a cylindrical member that includes a magnet roller 55 and is made of a rotatable nonmagnetic material. On the surface of the developing sleeve 51, as a plurality of magnetic poles, a first magnetic pole P1 (S pole), a second magnetic pole P2 (N pole), a third magnetic pole P3 (S pole), a fourth magnetic pole P4 (N pole), And the five magnetic poles of the fifth magnetic pole P5 (N pole) are formed by the magnet roller 55. Note that P1 to P5 in FIG. 1 indicate the distribution of the normal direction magnetic flux density (absolute value) on the surface of the developing sleeve 51 of the magnetic field formed by each magnetic pole.

  The developing sleeve 51 is subjected to blasting on the surface of the image forming region in the longitudinal direction (rotating axis direction) so that the developer can be favorably carried. A part of the surface of the developing sleeve 51 is partially exposed from the opening 61 of the casing 60 that forms the developing roller housing portion 62, and forms a developing region facing the photoreceptor 1.

  Further, a doctor blade 52 as a developer regulating member for regulating the layer thickness of the developer is provided on the upstream side in the surface movement direction of the developing sleeve 51 from the developing region. Further, a magnetic plate 58 is provided adjacent to the upstream side of the doctor blade 52 in the surface movement direction of the developing sleeve 51. The base of the magnetic plate 58 is supported on the upstream side surface of the doctor blade 52, and the tip side is bent substantially horizontally to form a facing surface 58 a that faces the surface of the developing sleeve 51 on the upstream side of the doctor blade 52. doing.

  Below the developing roller accommodating portion 62, a supply / recovery conveying path 53a and a circulating conveying path 54a are provided as a developer accommodating portion for accommodating a developer G, which is a two-component developer composed of a carrier and toner. As shown in FIG. 3, the circulation conveyance path 54 a communicates with the toner supply port 64 through an opening formed above the circulation conveyance path 54 a.

  The developer accommodating portion is partitioned by a partition wall 57 into a supply / recovery conveyance path 53 a on the developing sleeve 51 side and a circulation conveyance path 54 a on the toner supply port 64 side. The supply / recovery conveyance path 53a and the circulation conveyance path 54a on the toner supply port 64 side communicate with each other through an opening (not shown) provided at the end of the partition wall 57. The supply / recovery conveyance path 53 a on the developing sleeve 51 side includes a communication port 59 with the developing roller accommodating portion 62. A supply / recovery screw 53 and a circulation screw 54 for stirring and conveying the toner are provided in the supply / recovery conveyance path 53a and the circulation / conveyance path 54a, respectively. The supply / recovery screw 53 and the circulation screw 54 rotate counterclockwise as indicated by arrows in FIG.

The developer G in the developing device 5 is adjusted so that the ratio of toner in the developer (toner concentration) is within a predetermined range. Specifically, a toner replenishing device (not shown) is driven according to the consumption of toner in the developing device 5, and the toner stored in the toner container 11 (see FIG. 2) is circulated and conveyed through the toner replenishing device 54a. It is replenished inside.
A density detection sensor 56 for detecting the toner density of the developer is provided on the bottom surface of the circulation conveyance path 54a. When the density detection sensor 56 detects that the toner density is insufficient in the developer accommodating portion, a toner replenishing device (not shown) is driven, and enters the circulation conveyance path 54a from the toner container 11 (see FIG. 2) via the toner replenishing port 64. Toner is replenished.

  FIG. 5 is a top view schematically showing the circulation path of the developer G in the developing device 5, the broken arrow in FIG. 5 indicates the flow of the developer G, and the solid arrow in FIG. The flow of toner supplied from the toner supply port 64 is shown. In the developing device 5, the developer G in the supply / recovery conveyance path 53a is supplied to the development sleeve 51, and the developer G carried on the development sleeve 51 and passed through the development region is collected in the supply / recovery conveyance path 53a. . The density detection sensor 56 indicated by a broken-line square in FIG. 5 is installed below a portion of the casing 60 that forms the circulation conveyance path 54a.

Next, the operation of the developing device 5 will be described.
The toner replenished to the developing device 5 by the toner replenishing device is replenished from the toner replenishing port 64 into the circulation conveyance path 54a of the developer accommodating portion. The toner replenished to the circulation conveyance path 54 a of the developing device 5 is agitated with the developer G composed of toner and carrier by the circulation screw 54. In the circulation conveyance path 54 a, the developer G composed of toner and carrier and the replenished toner are conveyed in the axial direction while being agitated by the circulation screw 54, and the replenished toner is taken into the developer G.

  The developer G that has been transported to the circulation screw 54 and has reached the downstream end in the transport direction of the circulation transport path 54a passes through the opening at the end of the partition wall 57 (circulation downstream end opening 57a), and is supplied, recovered and transported. Move to the road 53a. The developer G in the supply / recovery conveyance path 53a is conveyed in the opposite direction to the developer G in the circulation / conveyance path 54a while being stirred by the supply / recovery screw 53. When the downstream end of the supply / recovery conveyance path 53a in the conveyance direction is reached, it passes through the opening at the end of the partition wall 57 (supply downstream end opening 57b) and moves to the circulation conveyance path 54a. As described above, the developer is circulated in the developer accommodating portion constituted by the supply / recovery conveyance path 53a and the circulation / conveyance path 54a by the supply / recovery screw 53 and the circulation screw 54. Further, as shown by arrows in FIGS. 1 and 3, the developing sleeve 51 rotates in the counterclockwise direction in the drawings.

  Of the developer G stirred and conveyed by the supply / recovery screw 53 in the supply / recovery conveyance path 53a, the developer G attracted to the developing sleeve 51 by the magnetic force of the fifth magnetic pole P5 of the magnet roller 55 is described later. And is carried on the developing sleeve 51. The developer G attracted by the magnetic pole of the fifth magnetic pole P5 is carried on the pumping portion 511 which is a supply position on the surface of the developing sleeve 51. The carrier in the developer G is attracted to the developing sleeve 51 by the magnetic force of the magnet roller 55 included in the developing sleeve 51 and is carried on the developing sleeve 51. In addition, the toner in developer G is charged with the opposite polarity to the carrier due to frictional charging with the carrier as developer G is agitated, and the electrostatic force acts between the carrier and is adsorbed to the carrier. The carrier is carried on the developing sleeve 51 together with the carrier. The developer G carried on the developing sleeve 51 moves around the developing roller 50 as the developing sleeve 51 rotates.

  The developer G carried on the developing sleeve 51 is conveyed counterclockwise in FIG. 1 as the developing sleeve 51 rotates, and reaches a position where the doctor blade 52 and the surface of the developing sleeve 51 face each other. Then, the developer G on the developing sleeve 51 passes through a gap (doctor gap) between the doctor blade 52 and the surface of the developing sleeve 51 at this position, so that the layer thickness is regulated, and the amount of the developer becomes an appropriate amount. Is done. On the upstream side of the doctor blade 52, a facing surface 58 a of the magnetic plate 58 is provided so as to face the developing sleeve 51. By the action of the facing surface 58a, the developer stirring function in the doctor blade 52 can be improved.

  When the developer G on the developing sleeve 51 that has passed through the doctor blade 52 is transported to the developing area facing the photosensitive member 1, the developer G stands on the developing sleeve 51 by the magnetic force of the magnet roller 55. Here, the developing sleeve 51 moves in the same direction in the developing region at a higher linear velocity than the surface of the photoreceptor 1. The carrier spiked on the developing sleeve 51 supplies the toner adhered to the carrier surface to the surface of the photoreceptor 1 while rubbing the surface of the photoreceptor 1. At this time, a developing bias is applied to the developing sleeve 51 from a power source (not shown), whereby a developing electric field is formed in the developing region.

Then, between the electrostatic latent image on the photosensitive member 1 and the developing sleeve 51, an electrostatic force directed toward the electrostatic latent image side acts on the toner on the developing sleeve 51. As a result, the toner on the developing sleeve 51 adheres to the electrostatic latent image on the photoreceptor 1. By this adhesion, the electrostatic latent image on the photoreceptor 1 is developed into a corresponding color toner image. Thereafter, the developer G that has consumed the toner on the developing sleeve 51 reaches the upper portion of the developing roller accommodating portion 62 as it rotates, and is separated from the developing sleeve 51 at this position.
At this time, the developer G on the surface of the developing sleeve 51 is at an inflection point 512 that is an agent separating magnetic pole constituted by the fourth magnetic pole P4 and the fifth magnetic pole P5 that are adjacent magnetic poles of the same polarity (N pole). The developing sleeve 51 is detached from the surface by the action of magnetic force.

Next, the characteristic part of the developing device 5 of the present embodiment will be described.
The developing device 5 includes a partition plate 520 whose upper end faces the entire surface in the longitudinal direction of the developing sleeve 51 with respect to the surface between the pumping portion 511 on the developing sleeve 51 and the inflection point 512. The partition plate 520 divides the space where the pumping unit 511 is opposed to the space where the inflection point 512 is opposed in the developing device 5, and the lower end portion is located above the supply / recovery conveyance path 53 a.
With such a configuration, the developer G separated at the inflection point 512 passes through the space on the side facing the inflection point 512 across the partition plate 520 along the inclined surface 521 of the partition plate 520, and the supply / recovery conveyance path. It is recovered in 53a. On the other hand, the developer G supplied from the supply / recovery conveyance path 53a to the surface of the developing sleeve 51 is supplied to the surface of the developing sleeve 51 through a space on the side facing the pumping portion 511 with the partition plate 520 interposed therebetween. .

The path of the developer G separated by the inflection point 512 and the path of the developer G supplied to the pumping unit 511 can be partitioned by the partition plate 520. For this reason, it is possible to effectively prevent the developer G separated at the inflection point 512 from being mixed with the developer G supplied to the pumping unit 511. Therefore, it is possible to effectively supply the developer G separated at the inflection point 512 to the developing sleeve 51 immediately by the supply / recovery integrated system in which the developer G separated at the inflection point 512 is collected in the supply / recovery conveyance path 53a. Can be suppressed.
Further, in the developing device 5, the developer G separated from the developing sleeve 51 at the inflection point 512 can flow on the inclined surface 521 of the partition plate 520. Further, the presence of the partition plate 520 can prevent the separated developer G from being attracted to the fifth magnetic pole P5 and re-magnetized on the surface of the developing sleeve 51.

When the repulsive magnetic field formed at the inflection point 512 is weak, the developer G is not so far away from the developer G and may be mixed with the developer G pumped up by the pumping unit 511 by the inertial force along the surface moving direction. The developer G that has passed through the development area has a low toner concentration. When development is performed in a state where the developer G is mixed with the developer pumped up normally, the developer G supplied to the development area is used. Thus, an abnormal image in which the image density varies is formed.
On the other hand, in the copying machine 500 provided with the developing device 5 of the present embodiment, the developer G separated at the inflection point 512 can be effectively suppressed from being immediately supplied to the developing sleeve 51, and therefore image fluctuation Can be suppressed, and stable image formation can be performed.

Further, the supply / recovery screw 53 of the developer supply / conveyance member rotates when the screw blade portion 53c, which is a conveyance blade portion, rotates around the screw shaft 53b, which is a conveyance rotation shaft extending in the rotation axis direction of the developing sleeve 51. The developer G in the supply / recovery conveyance path 53a is conveyed.
Here, in the space that is divided into two in the horizontal direction with the screw shaft 53b as a boundary in the supply / recovery conveyance path 53a, the space in which the screw blade portion 53c moves upward from below as the supply / recovery screw 53 rotates (see FIG. The space on the right side in 1) is defined as the wing rising space. On the other hand, a space (left space in FIG. 1) in which the screw blade portion 53c moves downward from above with the rotation of the supply / recovery screw 53 is defined as a blade-lowering space. At this time, as shown in FIG. 1, the developer G in the supply / recovery conveyance path 53a is supplied to the surface of the developing sleeve 51 from the wing rising space, and the lower end portion of the partition plate 520 is located above the screw shaft 53b or Located above the wing down space.

  With such a configuration, the developer G separated from the developing sleeve 51 at the inflection point 512 is transferred into the wing descending space, and is supplied, recovered, and conveyed along with the movement of the screw wing 53c in the wing descending space. It is taken into the developer G in the passage 53a and stirred. Accordingly, it is possible to more effectively suppress the developer G separated from the developing sleeve 51 from being immediately supplied to the developing sleeve 51 without being stirred with the developer G in the supply / recovery conveyance path 53a.

  As shown in FIG. 1, the partition plate 520 is inclined so that the horizontal position with respect to the rotation axis of the developing sleeve 51 is separated from the upper end portion to the lower end portion. With such a configuration, all of the developer G separated from the developing sleeve 51 at the inflection point 512 can be dropped to the far side from the developing sleeve 51 with the screw shaft 53b interposed between the partition plates 520. Thereby, it is possible to further effectively suppress the developer G separated at the inflection point 512 from being immediately supplied to the developing sleeve 51.

  As shown in FIG. 1, the lower end portion of the partition plate 520 is positioned above the upper end portion of the supply / recovery screw 53, and does not contact the developer G in the supply / recovery conveyance path 53a. A flexible sheet member such as Mylar may be provided at the lower end portion of the partition plate 520, and the lower end portion may be in contact with the developer G in the supply / recovery conveyance path 53a. By providing such a sheet member, it is possible to reliably supply the developer G separated from the developing sleeve 51 into the developer G in the supply / recovery conveyance path 53a that descends in the wing portion descending space. Thereby, it is possible to more effectively suppress the developer G separated at the inflection point 512 from being immediately supplied to the developing sleeve 51.

FIG. 6 is a cross-sectional explanatory view of the developing device 5 before starting use, and FIG. 7 is a perspective explanatory view of the developing device 5 before use. The image forming unit 6 shown in FIG. 4 is also in a state before use.
The casing of the developing device 5 includes a developing upper case 60a including the inner wall of the developing roller accommodating portion 62, and a developing lower case 60b including the inner wall of the developer accommodating portion composed of the supply / recovery conveying path 53a and the circulation conveying path 54a. It is mainly composed. A developing sleeve 51 is attached to the lower developing case 60b via a bearing (not shown), and a doctor blade 52, a magnetic plate 58, and the like are also attached. The upper development case 60a is attached to the upper side of the lower development case 60b to which these members are attached.

Further, the lower developing case 60b has a communication port seal that seals a communication port 59 that connects the developing roller accommodating portion 62 formed by the upper developing case 60a and the supply / recovery conveyance path 53a formed by the lower developing case 60b. A stop member 80 is attached. The communication port sealing member 80 can prevent the developer from leaking and scattering from the opening of the developing roller housing 62 when the image forming unit 6 is carried alone. Further, since the developer accommodating portion is blocked from the outside air, it is possible to prevent the developer G from being deteriorated due to the developer G coming into contact with air. At the start of use, the sealing by the communication port sealing member 80 is released, and the above-described image forming operation is performed.

  FIG. 8 is an exploded perspective view of a communication port sealing member 80 which is a communication port sealing means. The communication port sealing member 80 includes a frame body 81 that forms an opening as the communication port 59 and a seal member 82 that is directly bonded to the frame body 81 by thermocompression bonding (heat sealing) so as to cover the opening. ing. The seal member 82 is bonded to the frame body 81 from the front side end portion to the back side end portion in FIG. 6 so as to cover the opening serving as the communication port 59, and seals the communication port 59. The tip portion is returned to the front end portion by being folded back at the portion. In order to pull out the seal member 82, the tip end portion protrudes outward from the end portion of the frame 81 as shown in FIG. 4 and FIG.

  8 is pulled out in the right front direction in FIG. 8 in parallel with the opening surface, the seal member 82 which is thermocompression bonded to the frame 81 is peeled off, and the opening formed in the frame 81 appears, and the supply and recovery are performed. A communication port 59 between the conveyance path 53a and the developing roller accommodating portion 62 is formed. As a result, the developer can be supplied from the supply / recovery conveyance path 53 a to the developing roller accommodating portion 62 through the communication port 59.

  In addition, the frame body 81 has a bent portion 83 formed by bending the end portion of the frame body located in the lateral direction with respect to the direction in which the seal member 82 is pulled out. By providing such a bent portion 83, it is possible to increase the strength against the force that pulls the seal member 82 in the direction parallel to the opening surface and peels it off from the frame 81.

  As a material of the frame body 81, a resin material which is polypropylene (PP) and is strong against bending is used. The reason why the material is polypropylene (PP) is that the moldability is better than that of PET resin, and even a thick plate can be stably formed without causing cracks, fluffing and the like. It is. When a crack is generated, foreign matter such as dust at the cracked portion may enter the developer and an abnormal image such as a white stripe may be generated. In addition, the plate thickness is 0.8 [mm] or less. By providing the bent portion 83 in the frame body 81, it is possible to provide sufficient strength even with such a plate thickness as compared with a flat plate. Moreover, since polypropylene (PP) is used, it is cheaper than PET resin.

  As the seal member 82, an easy peel film (manufactured by Sanei Kaken) was used. The sealing member 82 made of this easy peel film is directly bonded to the polypropylene frame 81 by thermocompression bonding without using a double-sided tape. For this reason, when the seal member 82 is peeled off, there is no possibility that the double-sided tape abuts on the developing sleeve 51 or is mixed into the developing roller accommodating portion 62 to generate an abnormal image. Further, compared to the two-step manufacturing process in which the sealing member 82 is further bonded after the double-sided tape is applied, the manufacturing process is easy because the sealing member is directly bonded by thermocompression bonding.

  However, in the above configuration, the floating occurs at the folded portion 82 a of the seal member 82 on the back side of the developing device 5. When the lifting member pulls out the seal member 82, the seal member 82 may be caught by an edge portion or the like of the member disposed above the frame body 81, and the seal member 82 may be split or cut off in the middle. The problem that the film cannot be peeled off satisfactorily occurred.

Specifically, a facing surface 58 a of the magnetic plate 58 adjacent to the upstream side of the doctor blade 52 and bent substantially horizontally so as to face the surface of the developing sleeve 51 is disposed above the frame body 81. .
FIG. 9 is a perspective view showing the positional relationship between the frame 81 attached to the lower developing case 60b and the magnetic plate 58 on the rear side of the developing device. In the image forming region in the longitudinal direction of the developing sleeve 51, a facing surface 58a of the magnetic plate 58 is formed opposite to the blasted surface 51a of the developing sleeve 51 by bending the tip of the magnetic plate 58 substantially horizontally. Yes. On the other hand, at the back end that is outside the image forming region, the tip of the magnetic plate 58 is not bent, and the tip is not blasted with the developing sleeve 51 along the upstream side surface of the doctor blade 52. It is opposed to the blast region 51b. As a result, a magnetic seal is formed at the inner end of the developing sleeve 51 that is outside the image forming area, and leakage of the developer G from the end of the developing sleeve 51 is prevented.

  The longitudinal end portion of the communication port 59 formed by the frame body 81 is disposed on the far side of the end portion 58 b of the facing surface 58 a of the magnetic plate 58. When the sealing member 82 is bonded to the frame body 81 and folded back so as to cover the communication port 59, the folded portion 82a (see FIG. 8) of the sealing member 82 is located behind the end portion 58b of the facing surface 58a in the longitudinal direction. Placed in. Between the frame 81 and the opposing surface 58a of the magnetic plate 58, there is a narrow gap of about 1 to 2 [mm], and the folded seal member 82 is arranged in this narrow gap.

  In this configuration, when the seal member 82 is pulled out, the folded portion 82a of the seal member 82 passes through a position where the end portion 58b of the facing surface 58a of the magnetic plate 58 is disposed above. At this time, since the gap between the facing surface 58a of the magnetic plate 58 and the frame 81 is narrow, the folded portion 82a may be lifted up by the end portion 58b of the facing surface 58a of the magnetic plate 58 disposed above. If the seal member 82 is caught by the end portion 58b, the seal member 82 may be split or cut in the middle, and the seal member cannot be peeled off from the communication port 59 well. Further, the object to which the seal member 82 is caught is not limited to the magnetic plate 58.

  If the seal member 82 is torn, the image forming unit 6 is removed from the copying machine 500 main body, the developing device 5 is removed from the image forming unit 6, and the developing sleeve 51 is further removed from the developing device 5 to perform the recovery process. There is a need to. For this reason, the work is complicated and cannot be recovered by the user.

  In the developing device 5 of the present embodiment, the folded-back portion 82a of the seal member 82 is prevented from being caught by the end portion 58b of the facing surface 58a of the magnetic plate 58 disposed above, so that the floating-up portion 82a is lifted from above. A holding member 70 is provided. Further, the lower end portion of the partition plate 520 also has a function of suppressing the floating of the folded portion 82a from above.

  The material of the holding member 70 is, for example, a resin thin plate such as an Tolerance mirror, and the thickness of the thin plate is preferably 0.1 to 0.2 [mm]. If it is too thin, the force for pressing the bent portion 82a of the seal member 82 will be weak, and if it is too thick, the force for pressing will be too strong.

  The lower end portion of the pressing member 70 and the partition plate 520 suppresses the rising of the folded portion 82a of the sealing member 82 to the frame body 81 side, so that the sealing member 82 is an end portion of the opposing surface 58a of the magnetic plate 58 disposed above. 58b is prevented from being caught.

Such a pressing member 70 needs to be inserted into a narrow gap between the sealing member 82 adhered to the frame body 81 and the magnetic plate 58 around the end portion 58b of the facing surface 58a of the magnetic plate 58. In the present embodiment, the upper developing case 60a to which the pressing member 70 is attached is attached to the lower developing case 60b to which the magnetic plate 58, the sealing member 82, the magnetic plate 58 and the like are attached, so that the pressing member 70 and the sealing member 82 are attached. Set in a narrow gap between the magnetic plate 58.
On the other hand, in the configuration in which the seal member 82 is pressed by the lower end portion of the partition plate 520, the seal member 82 can be prevented from being caught by the magnetic plate 58 or the like without inserting the member into a narrow gap.

  In this way, by pressing the upper surface of the seal member 82 with the lower end portions of the pressing member 70 and the partition plate 520, the folded-back portion 82a of the seal member 82 can be prevented from rising when the seal member 82 is pulled out. Accordingly, the seal member 82 is prevented from being caught by the end portion 58b of the facing surface 58a of the magnetic plate 58 disposed above the frame 81. For this reason, when pulling out the seal member 82, the seal member 82 is prevented from being split or cut off in the middle, and the seal member 82 can be peeled off from the frame body satisfactorily.

  As described above, in the present embodiment, when the seal member 82 is pulled out, an example in which the lift of the folded portion 82a is not caught on the end portion 58b of the facing surface 58a of the magnetic plate 58 disposed above the frame body 81 is used. The present invention has been described. However, the present invention is not limited to the above-described embodiment, and it is obvious that the above-described embodiment can be modified as appropriate within the scope of the technical idea of the present invention, other than suggested in the above-described embodiment. For example, the present invention can be applied if the lifting of the folded portion of the seal member is caught by a member disposed above the frame, and the same effect can be obtained. In addition, the number, position, shape, and the like of the constituent members are not limited to the above-described embodiment, and can be set to a suitable number, position, shape, and the like in practicing the present invention.

  In the configuration in which the flexible sheet member is provided at the lower end portion of the partition plate 520, the flexible sheet member is attached so as to be positioned above the seal member 82 before the seal member 82 is pulled out. Then, by pulling out the seal member 82, the lower end portion of the flexible sheet member is brought into contact with the developer G in the supply / recovery conveyance path 53a.

  In the developing device 5 of the above-described embodiment, the developer that has consumed toner in the developing region is separated from the developer carrying member such as the developing roller 50, and is supplied back to the supply / recovery conveyance path 53a that is the developer supply conveyance path again. It is a collection integrated system. As another method for recovering the developed developer from the developer carrier, the development of the supply / recovery separation system for recovering the developed developer separated from the developer carrier in a developer transport path other than the developer supply path The device is known.

  In the supply / recovery separation type developing device, the developer amount for the entire developed developer decreases toward the downstream side in the transport direction in the developer supply transport path, and thus the decrease amount increases. As a configuration that suppresses the influence of the developer decreasing toward the downstream side in the transport direction in the developer supply transport path, the entire transport amount of the developer transported in the developer supply transport path is increased, or the developer supply There is known a configuration in which the transport speed for transporting the developer in the transport path is increased. Increasing the total amount of developer transported in the developer supply transport path leads to an increase in the size of the entire developing device, and increasing the transport speed leads to an increase in cost of the drive source and transport member.

  On the other hand, in the supply / collection integrated type developing device, the amount of the developer consumed for development decreases toward the downstream side in the transport direction in the developer supply transport path, but the decrease is small. For this reason, it is not necessary to increase the entire transport amount of the developer or increase the transport speed, and it is possible to reduce the size of the developing device and to reduce the cost of the drive source and the transport member.

However, after the developed developer returns to the developer supply conveyance path, there may be a problem that the developer is supplied again to the developer carrying member without being sufficiently stirred. Hereinafter, this problem is referred to as “re-pumping”. When re-pumping occurs, development is locally performed with a developer having a low toner concentration, and an uneven image may occur.
The developing device 5 according to the present embodiment includes a partition plate 520 and drops the developed toner in the wing descending space located at a position away from the developing roller 50 in the supply / recovery conveyance path 53a, thereby preventing re-pumping. .

  However, if the position of the partition plate 520 is not properly disposed, the developer separated from the developing roller 50 adheres to the developing roller 50 again before contacting the partition plate 520, and the re-pumping prevention function cannot be sufficiently obtained. There is. For this reason, it is calculated | required to arrange | position the position of the partition plate 520 appropriately so that re-pumping can be prevented more reliably.

  FIG. 10 is a schematic cross-sectional view of a conventional supply / collection integrated developing device 5 that does not include a partition plate 520. In the developing device 5 shown in FIG. 10, the developing sleeve 51, the supply / recovery screw 53, and the circulating screw 54 are rotated in the counterclockwise direction in the drawing. The circulation screw 54 may be configured to rotate in the clockwise direction.

  The developer G that has passed through the developing region is separated from the developing sleeve 51 toward the supply and recovery screw 53. The position at which the separated developer G falls determines whether the developer G is sufficiently agitated with the other developer G by the supply / recovery screw 53 or is re-pumped to the developing sleeve 51 with insufficient agitation. In FIG. 10, the path of the developer G that is separated from the developing sleeve 51 is indicated by a dashed arrow.

In the configuration of FIG. 10, a part of the developer G separated from the developing sleeve 51 is re-pumped with insufficient stirring. In particular, when the output image is a high image area image, the toner density after passing through the development area is low, and the developer G in the supply / recovery conveyance path 53a and the developer G after passing through the development area are low. And there is a difference in toner density. For this reason, when an image with a high image area is output, an abnormal image in which the image density is locally reduced may occur due to the re-pumping of the developer G having a lowered toner density.
Regarding the developer G in the supply / recovery conveyance path 53a and the circulation / conveyance path 54a, the developer G in the supply / recovery conveyance path 53a is conveyed by the supply / recovery screw 53 toward the back side in FIG. On the other hand, the developer G in the circulation conveyance path 54a is conveyed toward the front side in FIG.

  FIG. 11 is a cross-sectional view of the developing device 5 including the partition plate 520, as in the above-described embodiment, and is an explanatory diagram showing the path of the developer G that is separated from the developing sleeve 51 with a dashed arrow. As shown in FIG. 11, the developing device 5 of the present embodiment is provided with a partition plate 520 that guides the developer G separated from the developing sleeve 51 to a position far from the developing sleeve 51 in the supply / recovery conveyance path 53a. It is.

  As shown by the broken arrow in FIG. 11, the developer G that has passed through the developing region and separated from the developing sleeve 51 is transported along the partition plate 520, and is located far from the developing sleeve 51 in the supply / recovery transport path 53a. Fall into. The developer G that has fallen into the supply / recovery conveyance path 53 a is agitated with the other developer G in the supply / recovery conveyance path 53 a by the rotation of the supply / recovery screw 53 and then pumped up to the developing sleeve 51. Therefore, since the developer G that has passed through the development region is sufficiently stirred with the other developer G in the supply / recovery conveyance path 53a and then supplied to the developing sleeve 51, the occurrence of an abnormal image due to uneven toner density can be suppressed.

  Further, the developer G that has fallen from the partition plate 520 is required to fall at least on the side farther from the developing sleeve 51 than the screw shaft 53b. This is because, if the screw shaft 53b falls closer to the developing sleeve 51, it may be re-pumped before being stirred by the supply / recovery screw 53.

FIG. 12 is a cross-sectional view of the developing device 5 when the partition plate 520 is not properly arranged. Also in FIG. 12, the path of the developer G that is separated from the developing sleeve 51 is indicated by a dashed arrow.
As shown in FIG. 12, when the position of the partition plate 520 is not appropriate, the developer G separated from the developing sleeve 51 may adhere to the developing sleeve 51 again before it hits the partition plate 520. In this case, since the developer G after passing through the development region is not stirred by the supply and recovery screw 53, the developer G having a low toner concentration is supplied to the development region, leading to uneven image density.

The position definition of the front end of the partition plate 520 on the developing sleeve 51 side (hereinafter referred to as “partition plate front end portion 520a”) will be described. FIG. 13 is an explanatory view for defining the position of the partition plate front end portion 520a, and is a cross-sectional view showing the developing roller 50, the doctor blade 52, and the supply / recovery screw 52, in which the region affected by the repulsive magnetic force is described. .
“55a”, “55b”, and “55c” indicated by broken lines in FIG. 13 indicate the magnetic force in the “r direction” (the radial direction of the developing roller 50) acting on the carrier on the surface of the developing sleeve 51 around the separation position. The absolute value of is shown. A portion indicated by “55c” in the region α indicated by an ellipse represents a magnetic force acting in a direction away from the surface of the developing sleeve 51, that is, a repulsive magnetic force.

  The developer G is separated by receiving a force separating from the developing sleeve 51 by a repulsive magnetic force. The partition plate 520 needs to be arranged so that the partition plate tip 520a is positioned at a position where the developer G is separated from the developing sleeve 51. The position where the developer G is separated is set on the downstream side in the surface movement direction of the developing sleeve 51 with respect to the position where the repulsive magnetic force peak indicated by the one-dot chain line in FIG. In the portion where the repulsive magnetic force is acting, the developer G receives a force separating from the developing sleeve 51. Therefore, the developer G is once separated from the developing sleeve 51 within the range where the repulsive magnetic force indicated by the region α is acting. The developer G receives a force in a further away direction.

  When the magnetic force changes from repulsion to attraction (the direction in which the developing sleeve 51 is attracted), the developer G acts in the direction in which the developer G is attracted to the developing sleeve 51. The position of the front end 520a of the partition plate is preferably a position that is downstream of the developing sleeve 51 in the surface movement direction with respect to the position where the repulsive magnetic force peak is present, and is further downstream of the region where the repulsive magnetic force is working. Better. This is because even if the magnetic force changes from repulsion to attraction, the force does not become so large that the developer G adheres to the developing sleeve 51 immediately. However, if the position of the front end 520a of the partition plate changes too much to the downstream side after changing to the attractive magnetic force, the target function cannot be performed.

In FIG. 13, a virtual straight line connecting the rotation center of the developing sleeve 51 and the position where the repulsive magnetic force peak is indicated by a one-dot chain line β, and a virtual straight line connecting the rotation center of the developing sleeve 51 and the partition plate tip 520a. Indicated by γ. In the embodiment shown in FIG. 13, the angle θ of the front end 520a of the partition plate with respect to the position where the repulsive magnetic force peak is set to a position that is about 20 ° on the downstream side of the surface movement direction of the developing sleeve 51. Yes. When the position of the partition plate tip 520a is separated from the position where the repulsive magnetic force peak is such that the angle θ is 40 [°] or more, the developer G separated from the developing sleeve 51 contacts the partition plate 520. Before, there is a case where it reattaches to the developing sleeve 51. In this case, the partition plate 520 cannot perform the intended function.
The magnetic force calculation method is disclosed in, for example, Japanese Patent Application Laid-Open No. 2012-145937, and detailed description thereof is omitted.

Next, the inclination angle of the inclined surface 521 of the partition plate 520 will be described.
The developer G that has separated the developing sleeve 51 slides on the inclined surface 521 of the partition plate 520 and falls into the supply / recovery conveyance path 53a. In order for the developer G to slide on the inclined surface 521, there is a limit to the inclination of the inclined surface 521, and it is necessary to be at least the repose angle of the developer G. If the inclination angle is less than the repose angle of the developer G, the developer G that has landed on the inclined surface 521 may be deposited on the inclined surface 521 of the inclined surface 521. On the other hand, by setting the inclination angle of the inclined surface 521 to be equal to or greater than the repose angle of the developer G, it is possible to suppress the developer G from being deposited on the inclined surface 521, and the developer G separated from the developing sleeve 51. Can be more reliably guided to the supply / recovery conveyance path 53a.

The angle of repose of developer G is 30 to 50 [°]. The angle of repose varies depending on the fluidity and toner concentration of the toner, but hardly exceeds 50 [°]. Therefore, it is desirable to arrange the partition plate 520 so that the angle of the inclined surface 521 with respect to the horizontal direction is 50 [°] or more. However, if the angle of the inclined surface 521 with respect to the horizontal direction is too steep, the original function of transporting the developer G to a position far from the developing sleeve 51 cannot be performed.
In the embodiment shown in FIG. 13, in order to achieve both the margin for the angle of repose and the function of dropping the developer G to a position far from the developing sleeve 51, the inclination of the inclined surface 521 with respect to the horizontal direction is 55 [°]. In addition, a partition plate 520 is disposed.
In addition, since the measuring method of a repose angle is disclosed by Unexamined-Japanese-Patent No. 2012-145937 etc., detailed description is abbreviate | omitted.

  As for the arrangement of the partition plate 520, the position of the partition plate tip 520a is determined by the positional relationship with the range in which the repulsive magnetic force acts, and the inclination of the inclined surface 521 with respect to the horizontal direction is determined with respect to the angle of repose of the developer G. This relationship is not limited to the same configuration as the developing device 5 of the present embodiment, and is a setting that can be applied to other developing devices.

  The supply / recovery integrated developing device 5 draws the developer G from the supply / recovery conveyance path 53a to the developing sleeve 51, and the toner is developed when it passes through the development region. Therefore, the developer G after passing through the development region has a reduced toner concentration (ratio of the toner weight to the developer weight). When the developer G returned to the supply / recovery conveyance path 53a is reduced in toner density and pumped up to the developing sleeve 51 again without being sufficiently stirred with the other developer G in the supply / recovery conveyance path 53a, the toner The developer G having a lowered density is transported to the development area. In such a case, the amount of toner developed on the latent image on the photoconductor 1 decreases when the toner density is low, and therefore, the amount of toner on the photoconductor 1 decreases and a portion with a low image density is generated. .

  On the other hand, in the developing device 5 of this embodiment, the partition plate 520 that guides the developer G using the developer G that has passed through the developing region as a guide member is used to remove the developing sleeve 51 from the supply / recovery conveyance path 53a. The developer G is conveyed to a distant part. Thereby, it is possible to suppress the pumping up to the developing sleeve 51 again with insufficient stirring.

  Further, in order to prevent the pumping up again, it is necessary to dispose the partition plate 520 so as to land on the inclined surface 521 of the partition plate 520 after the developer G is separated from the developing sleeve 51. Usually, when the developer G is spoken from the developing sleeve 51, a repulsive magnetic force (force acting in a direction away from the developing sleeve 51), gravity, and centrifugal force are used. Among these, the repulsive magnetic force is an important factor when the developer G is separated. In the developing device 5 of the present embodiment, the partition plate 520 is disposed so as to come into contact after the developer G is separated from the developing sleeve 51 by the repulsive magnetic force. Accordingly, the purpose of transporting the developer G far from the developing sleeve 51 by the partition plate 520 after the developing agent G is separated from the developing sleeve 51 can be achieved.

  Since the developing device 5 of the present embodiment is a supply / recovery integrated system, it is possible to prevent the occurrence of an abnormal image due to re-pumping while realizing downsizing of the developing device and cost reduction of the driving source and the conveying member. By using the partition plate 520 as an abnormal image countermeasure that has been improved only with the developing roller, the tolerance of the developing roller can be widened and reduced.

What has been described above is merely an example, and the present invention has a specific effect for each of the following modes.
(Aspect A)
Development of a developer carrying member such as a developing sleeve 51 that rotates so as to move the surface from below to above in the developing region, and development such as a supply and recovery conveyance path 53a that extends below the developer carrying member in the direction of the rotation axis of the developer carrying member. The developer supply / conveyance is performed while the two-component developer such as developer G including the toner and the carrier in the developer supply / conveyance path is transported along the axial direction of the developer carrier. And a developer supply / conveyance member such as a supply / recovery screw 53 for supplying the two-component developer in the path to the surface of the developer carrier, and the two-component developer carried on the surface of the developer carrier to the development region. The toner in the two-component developer is transported and adhered to the latent image on the surface of the latent image carrier to develop the latent image, and the two-component developer that has passed through the development region is removed from the developer carrier. A developing device that separates and collects in the developer supply conveyance path In a developing device such as the above, the supply position of the pumping unit 511 to which the two-component developer is supplied from the inside of the developer supply transport path on the surface of the developer carrying member, and the two-component developer that has passed through the development region are the developer. A space in which the upper end faces the entire surface in the rotation axis direction of the developer carrying member and the supply position in the developing device faces the surface between the inflection point 512 and the like separated from the carrying member. And a partition plate such as a partition plate 520 whose lower end is positioned above the developer supply transport path.
According to this, as described in the above embodiment, the developer separated at the separation position passes through the space on the side where the separation position opposes across the partition plate, and is collected into the developer supply conveyance path. On the other hand, the developer supplied from the developer supply / conveyance path to the surface of the developer carrier is supplied to the surface of the developer carrier through the space on the side where the supply positions are opposed with the partition plate in between. Since the developer path separated at the separation position and the developer path supplied to the supply position can be partitioned by the partition plate, the developer separated at the separation position is supplied to the supply position. Mixing can be effectively suppressed. Therefore, in this aspect, it is effective that the developer separated at the separation position is immediately supplied to the developer carrying member by the supply / recovery integrated system that collects the developer separated at the separation position in the developer supply conveyance path. Can be suppressed.
(Aspect B)
In the aspect A, the magnet roller 55 is disposed inside the developer carrying member such as the developing sleeve 51 and generates a repulsive magnetic force so that the two-component developer such as the developer G is separated from the developer carrying member at the separated position. The closest position of the partition plate such as the partition plate tip 520a closest to the partition plate such as the partition plate 520 on the surface of the developer carrying member is repulsive on the surface of the developer carrying member. It is located downstream of the developer carrying member in the surface movement direction with respect to the position where the repulsive magnetic force is maximized, such as the position where the magnetic force peak is reached.
According to this, as described in the above embodiment, the developer separated from the developing sleeve can be landed on the partition plate up to a position where the repulsive magnetic force is maximized, and re-pumping can be prevented more reliably.
(Aspect C)
In aspect B, the closest position of the partition plate such as the front end portion 520a of the partition plate is the direction of surface movement of the developer carrier relative to the region affected by the repulsive magnetic force on the surface of the developer carrier such as the developing sleeve 51. Located downstream.
According to this, as described in the above embodiment, re-pumping can be prevented. This is due to the following reason. That is, when the magnetic force changes from repulsion to attraction (the direction in which the developer carrying member is attracted), the developer such as developer G acts in the direction in which the developer is attracted to the developer carrying member. However, even if the magnetic force changes from repulsion to attraction, the force is not so large that the developer is immediately attached to the developer carrying member.
(Aspect D)
In aspects A to C, the developer supply / conveyance member such as the supply / recovery screw 53 is a screw blade portion centered on the conveyance rotation axis such as the screw shaft 53b extending in the rotation axis direction of the developer carrying member such as the developing sleeve 51. The two-component developer such as the developer G in the developer supply transport path such as the supply / recovery transport path 53a is transported by the rotation of the transport blades such as 53c and the developer supply transport member in the developer supply transport path The space divided into two in the horizontal direction with the transport rotation axis as the boundary is a wing rising space in which the transport wing moves upward from below as the developer supply transport member rotates, and the transport wing from the top When the wing part descending space moving downward is used, the developer in the developer supply conveyance path is supplied from the wing part ascending space to the surface of the developer carrying member, and the lower end of the partition plate such as the partition plate 520 is Above the conveyance rotation axis or the wing lowering space Located above.
According to this, as described in the above embodiment, the developer separated from the developer carrier at the separation position is transferred into the wing descending space, and the transport wing moves in the wing descending space. Accordingly, the toner is taken into the developer in the developer supply conveyance path and stirred. Thereby, it can suppress more effectively that the developer separated from the developer carrier is immediately supplied to the developer carrier without being agitated with the developer in the developer supply conveyance path.
(Aspect E)
In any one of the aspects A to D, the partition plate such as the partition plate 520 is hung from the upper end portion to the lower end portion so that the horizontal position with respect to the rotation axis of the developer carrier such as the developing sleeve 51 is separated. It is inclined.
According to this, as described in the above embodiment, all of the developer separated from the developer carrying member at the separated position can be dropped to the far side from the developer carrying member with the conveyance rotation shaft interposed between the partition plates. . Thereby, it can suppress more effectively that the developer separated in the separation position is immediately supplied to the developer carrying member.
(Aspect F)
In the aspect E, the inclination angle such as the inclination angle of the inclined surface 521 of the partition plate such as the partition plate 520 is larger than the repose angle of the two-component developer such as the developer G.
According to this, as described in the above embodiment, the two-component developer can be suppressed from being deposited on the partition plate, and the two-component developer separated from the developer carrier such as the developing sleeve 51 can be more reliably secured. The developer can be guided into the developer supply / conveyance path such as the supply / recovery conveyance path 53a.
(Aspect G)
In any one of the aspects A to F, a developer carrier housing portion such as a developing roller housing portion 62 that houses a developer carrier such as the developing sleeve 51, and a developer supplied to the developer carrier are housed. A frame 81 or the like that forms a communication port such as a communication port 59 that communicates the developer accommodating portion including the developer supply conveyance path such as the supply / recovery screw 53, and the developer carrier accommodating portion and the developer accommodating portion. a frame body, the one end portion in the rotation axis direction so as to cover the communication port to the other end portion is adhered to the frame body, and, folded at the other end, such as sealing member 82 extending to one end and a sealing member, by peeling off from the frame by pulling out the seal member from one end side to the opening direction parallel to the surface of the communication port, in a configuration for releasing the seal of the communication port, the partition plate such as the partition plate 520 The bottom end of the seal lifts the folded part of the seal member Feel more alert.
According to this, as described in the above embodiment, the seal member that seals the communication port between the developer carrier housing portion and the developer housing portion can be satisfactorily pulled out and peeled off.
(Aspect H)
In any of the aspects A to G, the developer is supplied from the developer supply conveyance path such as the supply / recovery conveyance path 53a to the surface of the developer carrier such as the developing sleeve 51 and is carried on the surface of the developer carrier. A developer regulating member such as a doctor blade 52 that regulates the amount of developer toward the developing region, and a facing surface 58a facing the developer carrying member upstream of the developer regulating member with respect to the surface movement direction of the developer carrying member. And a magnetic plate such as a magnetic plate 58 having opposing surfaces such as.
According to this, as described in the above embodiment, according to this, as described in the above embodiment, the developer restricting member regulates the developer by the action of the opposing surface of the magnetic plate. The developer stirring effect can be obtained.
Furthermore, by providing the configuration of the aspect D, the sealing member is prevented from being damaged due to the sealing member being caught on the magnetic plate, and even in the aspect including the magnetic plate, the sealing member can be satisfactorily pulled out and peeled off. it can.
(Aspect I)
At least a latent image carrier and a developing unit in an image forming apparatus such as a copying machine 500 including a latent image carrier such as the photosensitive member 1 that carries the latent image and a developing unit that develops the latent image on the latent image carrier. In the process cartridge such as the image forming unit 6 that is held on a common holding body as a unit and detachable from the main body of the image forming apparatus, the developing device according to any one of the aspects A to H is used as the developing unit. A developing device such as 5 is used.
According to this, as described in the above embodiment, the development in the image forming apparatus including the developing device that can effectively suppress the developer separated at the separation position from being immediately supplied to the developer carrying member. The apparatus can be easily replaced, and the maintainability of the image forming apparatus is improved.
(Aspect J)
At least a latent image carrier such as the photosensitive member 1, a charging unit such as a charging device 40 for charging the surface of the latent image carrier, an exposure device 12 for forming an electrostatic latent image on the latent image carrier, and the like. In the image forming apparatus such as the copier 500 having the latent image forming unit and the developing unit for developing the electrostatic latent image into a toner image, the developing unit is any one of the modes A to H. A developing device such as the developing device 5 is used.
According to this, as described in the above embodiment, a decrease in image density caused by the developer separated at the separation position being immediately supplied to the developer carrying member is suppressed, and stable image formation is performed. be able to.

DESCRIPTION OF SYMBOLS 1 Photoconductor 1Y Yellow photoconductor 1C Cyan photoconductor 1K Black photoconductor 1M Magenta photoconductor 2 Photoconductor cleaning device 2a Cleaning blade 3 Document conveyance section 4 Document reading section 4a Charging roller 5 Developing device 6 Image forming unit 7 Feeder 8 Intermediate transfer belt 9 Primary transfer bias roller 10 Intermediate transfer unit 11 Toner container 12 Exposure device 19 Secondary transfer bias roller 20 Fixing device 25 Paper discharge roller pair 26 Paper feed cassette 27 Paper feed roller 28 Registration roller pair 30 Ejection Paper tray 40 Charging device 50 Developing roller 51 Developing sleeve 51a Blast surface 51b Non-blasting region 52 Doctor blade 53 Supply recovery screw 53a Supply recovery conveyance path 53b Screw shaft 53c Screw blade 54 Circulation screw 54a Circulation conveyance path 55 Magnet roller 56 Concentration detection Sensor 58 Magnetic plate 57 Partition wall 58a Opposing surface 58b End portion 59 Communication port 60 Casing 60a Development upper case 60b Development lower case 61 Opening portion 62 Development roller storage portion 64 Toner supply port 70 Holding member 80 Communication port sealing member 81 Frame 82 Seal member 82a Folding part 83 Bending part 100 Printer part 500 Copying machine 511 Pumping part 512 Inflection point 520 Partition plate 520a Partition plate tip 521 Inclined surface G Developer L Laser light P Transfer paper P1 First magnetic pole P2 Second magnetic pole P3 3rd magnetic pole P4 4th magnetic pole P5 5th magnetic pole

JP 2005-189249 A JP 2006-189734 A JP 2009-251036 A JP 2010-276974 A

Claims (9)

A developer carrier that rotates to move from the bottom to the top in the development region;
Wherein disposed in the developer carrying member of the developer supply conveyance path to below extending in the rotation axis direction of the developer carrying member, said developing a two-component developer containing toner and carrier of the developer supply conveyance path agent while transporting along the axial direction of the bearing member, and a developer supply conveyance member supplying the two-component developer on the surface of the developer carrying member of the developer supply conveyance path,
Wherein conveying the developer carrying member a two-component developer carried on the surface of the developing area, the toner in the two-component developer in the developing region is adhered to the latent image on the latent image bearing member surface latent image as well as developing a two-component developer having passed through the developing region is separated from the developer carrier in the developing device for collecting the developer supply conveyance path,
A supply position in which the two-component developer from the developer supply conveyance path on the surface of said developer carrying member is supplied, a separated position in which the two-component developer having passed through the developing region is separated from the developer carrier with respect to the surface between the opposed upper end portion over the entire axial direction of the developer carrying member, wherein said supply position is the opposite spatial separation position within the developing device and the space opposed A partition, a partition plate having a lower end located above the developer supply transport path ,
A developer carrier housing portion for housing the developer carrier;
Contains a developer to be supplied to the developer carrying member, and includes a developer containing portion including the developer supply transport path;
A frame that forms a communication port for communicating the developer carrying member accommodating portion and the developer accommodating portion;
A seal member that is bonded to the frame body from one end portion to the other end portion in the rotation axis direction so as to cover the communication port, and is folded back at the other end portion side and extends to the one end portion side. Prepared,
With a configuration in which sealing of the communication port is released by pulling out the seal member from the one end side in a direction parallel to the opening surface of the communication port and peeling it from the frame body,
A developing device lower portion of the partition plate and wherein Rukoto presser lifting of folded portion of said sealing member. The developing device according to claim 1.
Wherein disposed inside the developer carrying member, comprising a magnetic field generator for generating a repulsion magnetic force as a two-component developer in the spaced position is separated from the developer carrier,
The partition plate closest position where the partition plate is closest to the surface of the developer carrying member, relative to the position where the repulsive magnetic force on the surface of said developer carrying member is maximum, the developer carrier A developing device characterized in that the developing device is located on the downstream side in the direction of surface movement of the toner. The developing device according to claim 2.
The partition plate closest position, the region where the repelling magnetic force on the surface of said developer carrying member is affected, that being located in the surface movement direction downstream side of the developer carrying member A developing device. In the developing device according to any one of claims 1 to 3,
The developer supply conveyance member, a two-component developer of the developer supply conveyance path conveyed by the conveying vanes portion around the transport rotation axis extending in the direction of the rotation axis of said developer carrying member is rotated ,
The space is divided into two in the horizontal direction as a boundary the transport rotation axis of the developer supply conveyance member by the developer supply conveyance path, the transporting blade section with the rotation of the developer supply conveyance member from below wing portion increases space moves upward, and when said transporting blade unit has a blade unit falling space which moves from top to bottom,
The developer in the developer supply conveyance path is supplied to the developer carrying member surface from the wing portion increases space,
The developing device according to claim 1, wherein a lower end portion of the partition plate is located above the conveyance rotation shaft or above the wing portion descending space. In the developing device according to any one of claims 1 to 4,
The partition plate is away a horizontal position relative to the rotation axis of the developer carrier over the lower portion from the upper portion, a developing device which is characterized in that inclined. The developing device according to claim 5.
The developing device according to claim 1, wherein an inclination angle of the partition plate is larger than an angle of repose of the two-component developer . The developing device according to any one of 請 Motomeko 1 to 6,
Wherein the developer supply conveyance path is fed to the surface of the developer carrying member, a developer regulating member for regulating an amount of the developer carrying member carried on the surface of the developer toward the developing region,
Wherein upstream of said developer regulating member with respect to the surface movement direction of the developer carrying member, a developing apparatus, comprising a magnetic plate having a facing surface that faces the developer carrying member. A latent image carrier for carrying a latent image;
At least the image bearing member and said developing means and common is held by the holding member with the image forming apparatus main body as one unit of the image forming apparatus and a developing means for developing the latent image on the latent image bearing member In the process cartridge that can be attached and detached,
Wherein as a developing unit, a process cartridge, which comprises using a developing device according to any one of claims 1 to 7. At least a latent image carrier;
A charging means for charging said image bearing member surface,
A latent image forming means for forming an electrostatic latent image on said image bearing member,
In an image forming apparatus having developing means for developing the electrostatic latent image into a toner image,
Wherein as a developing unit, an image forming apparatus which comprises using a developing device according to any one of claims 1 to 7.

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