JP6090652B2 - Developing device, image forming apparatus, and process cartridge - Google Patents

Description

  The present invention relates to a developing device used for a copying machine, a facsimile, a printer, and the like, and an image forming apparatus and a process cartridge using the developing device.

  Conventionally, developing devices using a two-component developer containing toner and a magnetic carrier have been widely used. In this type of developing device, a developer is carried on the surface of a developer carrying member having a plurality of magnetic poles therein, the surface of which rotates, and on the surface of the latent image carrying member in a developing region facing the latent image carrying member. A toner that develops a latent image on a latent image carrier by supplying toner in the developer to the latent image is widely used (for example, Patent Documents 1 to 3). The developing devices described in Patent Documents 1 to 3 include a plurality of developer transport members that transport the developer in a direction parallel to the rotation axis of the developer carrier. Then, while circulating the developer in the developer transport path in which the developer transport member is disposed, a part of the circulating developer is supplied to the surface of the developer carrier, and the developer that has passed through the development region is the developer. The developer is collected from the surface of the carrier into the developer conveyance path and is circulated together with other developers. Further, since toner is consumed in the development area, toner is appropriately replenished into the developer conveyance path from a toner replenishment port provided in a part of the developing device according to the toner consumption. The replenished toner is stirred and mixed while being transported by the developer transport member together with the developer in the developer transport path.

As in the developing devices described in Patent Documents 1 to 3, in a developing device using a two-component developer, an initial developer and a developer carrying member accommodated in the developing device at the time of shipment and transportation of the developing device, Need to be shielded. The reason is that the developer may adhere to the surface of the developer carrying member when a long time elapses while the surface of the developer carrying member and the developer are in contact with each other.
Therefore, a two-component developer is filled in the developing device at the factory, and a sheet member that shields the space for storing the developer in the developing device and the developer carrying member is assembled to the developing device, and this developing device is connected to the image forming apparatus. Shipped in the state of being set in the main body. Also, when a developing device having a shorter device life than the image forming apparatus main body is shipped as a replacement developing unit, the sheet member may be shipped in a state assembled with the developing device.
After the user receives the image forming apparatus or the developing unit as a product, the user removes the sheet member that shields the developer and the developer carrier attached to the developing apparatus, and enables the developing operation. Start.

  Japanese Patent Laid-Open No. 2004-133242 shields an opening that communicates between the inside of the developer carrying path that supplies the developer to the developer carrying body and the developer carrying body while the developer is carried by the developer carrying member. Thus, a developing device in which a sheet member is bonded to a developing casing is described. In this developing device, the sheet member is pulled out in parallel with the axial direction of the developer carrying member to remove the sheet member, and the developer in the developer carrying path can be supplied to the developer carrying member by the developer carrying member. It is a configuration.

  In this developing device, the developer conveying path disposed opposite to the developer carrying member serves both as an action of supplying the developer to the developer carrying member and a function of collecting the developer from the developer carrying member. The supply and recovery integrated system. In the developer conveying path disposed opposite to the developer carrying member, the developer inside the developer carrying path is supplied to the developer carrying member, and the developer whose toner has been consumed by the development returns again to the same developer carrying path. The operation in which the developer returned from the developer carrying member into the developer transport path is used for development is continuously repeated in the axial direction in the developer transport path. As a result, since the developer whose toner density has decreased after passing through the development region is repeatedly used for development, the amount of toner contained in the developer carried on the developer carrying member gradually decreases in the axial direction. As a result, a density deviation in the axial direction occurs in the toner image in which the latent image is developed on the latent image carrier.

In Patent Document 2 and Patent Document 3, both a supply conveyance path for supplying a developer to a developer carrying body and a collection conveyance path for collecting the developer from the developer carrying body are opposed to the developer carrying body. A supply recovery separation type developing device is described.
In this type of developing device, the developer in the supply conveyance path is supplied to the developer carrying member, and the developer whose toner has been consumed in the development area is collected in the collection conveyance path and newly replenished with toner. The operation of returning to the supply conveyance path again and supplying the developer carrier is repeated. Therefore, the supply / recovery separation type developing device is unlikely to cause an image density difference at both ends in the longitudinal direction of the image, unlike the supply / recovery integrated type developing device.

However, this supply / recovery separation type developing device shields the developer and developer carrier in the developer conveyance path by the sheet member assembled to the developing device at the time of shipment as compared to the supply / recovery integrated type developing device. Difficult to do. This is due to the following reason.
In other words, in the supply / collection integrated type developing device, the path that connects the developer transport path in which the initial developer is accommodated and the developer carrying body supplies the developer in the developer transport path to the developer carrying body. Only the path through the opening for. Therefore, the shielding part by the sheet member need only be the opening. On the other hand, in the supply / recovery separation type developing device, the path through the supply opening for supplying the developer in the supply conveyance path to the developer carrying member, and the developed developer from the developer carrying member. There are two paths: a path through a recovery opening for recovering the liquid into the recovery transport path. Therefore, in the case of the supply / recovery separation method, it is necessary to shield the range of the opening having a wider range and a complicated shape than the supply / recovery integrated method by the sheet member. It is difficult to bond the sheet member to the developing casing so as to shield the range of the opening having such a wide range and a complicated shape.

  As a configuration capable of solving such problems, Japanese Patent Application No. 2011-247053 (hereinafter referred to as “prior application”) has a box-like shape for hermetically enclosing an initial developer in a supply / separation type developing device. A configuration in which an initial developer container is installed above the developing device is described. In this configuration, an initial agent supply opening that communicates the initial developer container and the developer conveyance path is provided, and a sheet member that shields the initial agent supply opening is assembled when the developing device is shipped. . When starting use, the sheet member is removed to drop the initial developer in the initial developer container into the developing device, supply the initial developer into the developer transport path, and transport the developer. The developer in the path can be supplied to the developer carrying member. In this developing device, in the state where the sheet member is assembled, there is no developer in the developer conveyance path, and the development can be performed without shielding the developer conveyance path and the path that connects the developer carrier. It is possible to prevent the developer from coming into contact with the agent carrier. In addition, since only the initial agent supply opening is shielded by the sheet member, it is possible to adhere the sheet member to the developing casing so as to shield the opening, as in Patent Document 1. .

  However, in the developing device having the initial developer container as in the previous application, the initial developer container becomes unnecessary after the sheet member is removed. Even if it is no longer necessary, if the initial developer container is removed, the developer may leak from the initial agent supply opening.If the developing device is set in the image forming apparatus main body without removing the initial developer container, the initial developer container may be removed. Space for arrangement is wasted, leading to an increase in the size of the apparatus.

  The present invention has been made in view of the above problems, and its object is to provide a developing device capable of preventing the developer from coming into contact with the developer carrier in a state before use, while preventing an increase in size of the device, An image forming apparatus including the developing device and a process cartridge are also provided.

In order to achieve the above object, according to the first aspect of the present invention, a developer comprising a magnetic carrier and a toner is carried on a surface by a plurality of magnetic poles provided therein, and the cylindrical surface rotates to form a latent image. a bearing member opposite to the developing region by the image bearing member a developer carrying member for supplying toner to the latent image on the surface of the developer in the developer conveyance path of the internal developer is transported, the developing agent conveyed in the axial direction of the bearing member, a supply transport member for supplying the developer to the developer carrying member, a developing casing that forms the developer conveying path, said supported on the developer carrying member developing in the developing device having a developer regulating member for regulating the amount of agent, the developer regulating member is disposed so as to face the lower portion of the developer carrying member, in the axial direction of said developer carrying member extending Mashimashi, among the developer carrying member of the developer transport path Comprising removably sheet member for shielding the developer passage openings for communicating the door, in the state of attaching the said sheet member, for shielding the developer passage openings of the sheet member in a cross section perpendicular to the axial direction one end side to the portion, wherein the developer gap between the regulating member and the developer carrying member through said sheet member, said end portion of said one end of the sheet member and said developer regulating member and the developer located outside the gap between the bearing member, the other end to the portion for shielding the developer passage openings of the sheet member, wherein provided above the portion of the developer carrying path said developing the opening of the upper side of the casing through which the sheet member, the pulling end of said other end of said sheet member is separated from the developer carrier with respect to the opening of the developing casing It is characterized in that the fixed to the outer.

Since the developer cannot pass through the sheet member, in order for the developer in the developer conveyance path to reach the opposite space across the sheet member, the end of the sheet member in the cross section orthogonal to the axial direction It is necessary to wrap around from the outside.
In a developing device provided with a conventional sheet member, the end of the sheet member in a cross section orthogonal to the axial direction is located inside the developing casing of the developing device. For this reason, in order to prevent the developer from flowing around from the outside of the end portion of the sheet member, it is necessary to bond the vicinity of the end portion of the sheet member to the developing casing without any gap. It is necessary to secure a bonding margin for bonding. In addition, it is difficult to secure a margin for the developing casing in an opening having a wide opening range and a complicated shape like a supply / separation type developing device. It was difficult to do.

  In the present invention, one end side of the sheet member passes through a regulation gap that is a gap between the developer regulating member and the developer carrying member, and the end portion is outside the regulation gap. In order for the developer to go around from the outside of the end portion of the sheet member, it is necessary to pass through the regulation gap. The regulation gap is a gap that allows the developer held on the surface of the developer carrying member by magnetic force to pass along with the surface of the rotating developer carrying member during the image forming operation. For this reason, the developer that is not carried on the surface of the developer carrying member hardly passes. Therefore, in the present invention, it is possible to prevent the developer from reaching the surface of the developer carrying member from the outside of the end portion on one end side of the sheet member without bonding the sheet member to the developing casing. .

  Further, the other end of the sheet member passes through the upper opening provided in the upper portion of the developer transport path of the developer casing, and the end is outside the developer casing. In order for the developer inside to go around from the outside of the end of the sheet member, it is necessary to pass through the upper opening. Since the upper opening is positioned above the developer transport path, some external force is applied to the developer, and the developer cannot pass through the upper opening unless the developer moves upward against gravity. In the state where the sheet member is attached, the developer conveying member that imparts conveying force to the developer in the developer conveying path is not driven, and there is little opportunity for external force to be applied to the developer. Passing is unlikely to occur. Even if the developer passes through the opening, the developer passes outside the developing casing of the developing device, so that the developer leaks out, but the developer is on the surface of the developer carrier. It is possible to prevent reaching. Therefore, even if the sheet member is not bonded to the developing casing, it is possible to prevent the developer from reaching the surface of the developer carrying member from the outside of the other end of the sheet member. The problem of the developer leaking out can be easily solved by providing a sealing means for closing the gap between the edge of the developing casing forming the opening and the sheet member.

  For both the end portion on one end side and the end portion on the other end side of the sheet member, the developer wraps around from the outside of the end portion of the sheet member to the developer carrying member without bonding the sheet member to the developing casing. It can be prevented from reaching. Since no adhesion is required, it is not necessary to secure a margin for adhesion to the developing casing, and even a developer passage opening with a wide opening range and a complicated shape can be shielded with a sheet member before use. In this state, the developer in the developer conveyance path can be prevented from coming into contact with the developer carrying member. Further, since the developer is accommodated in the developer conveyance path, it is not necessary to provide a space for accommodating the initial developer different from the developer conveyance path unlike the above-mentioned earlier developer container. The enlargement of the apparatus can be prevented.

  According to the present invention, there is an excellent effect that it is possible to prevent the developer from coming into contact with the developer carrying member in a state before use while preventing an increase in the size of the developing device.

Cross-sectional explanatory drawing of the developing device before use. 1 is a schematic configuration diagram of a copier according to an embodiment. The schematic block diagram of an image creation part. Cross-sectional explanatory drawing of a developing device. FIG. FIG. 3 is a schematic diagram illustrating movement of a developer in a longitudinal direction in a developing device. The perspective view which shows a part of developing device of the developing device before use with sectional drawing. Sectional explanatory drawing of the axial direction edge part vicinity of the developing device before use. Sectional explanatory drawing before use of a developing device provided with a sheet winding apparatus. Explanatory drawing of a state where a shielding sheet is removed by a developing device having a sheet guide surface, (a) is a perspective explanatory view of an axial end portion of the developing device, and (b) is an enlarged explanation of a region η in (a). Figure. FIG. 6 is a perspective explanatory view of an axial end portion in a state where a shielding sheet is attached by a developing device having a sheet guide surface. Sectional explanatory drawing before use of the developing device from which the position of a cover opening part differs from the structure shown in FIG. Sectional explanatory drawing before use of the image development apparatus of the modification 1. FIG. FIG. 10 is an enlarged cross-sectional view of the vicinity of a sheet cleaning member of a developing device according to Modification 1; FIG. 15 is an enlarged cross-sectional view of the vicinity of a sheet cleaning member having a configuration in which the relationship between the length of the free end side of the sheet cleaning member and the thickness of the developing cover is different from that in FIG. FIG. 10 is an enlarged cross-sectional view in the vicinity of a sheet cleaning member of a developing device according to Modification 2;

Hereinafter, an embodiment in which the present invention is applied to a tandem type color copying machine (hereinafter referred to as a copying machine 500) as an image forming apparatus 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 feed unit 7 includes a paper feed cassette 26 that stores transfer paper P that is a recording medium, and a paper feed roller 27 that feeds the transfer paper P in the paper feed cassette 26 toward 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 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. . The primary transfer bias rollers 9 (Y, M, C, K) transfer primary toner images formed on the surfaces of the photoreceptors 1 (Y, M, C, K) to the intermediate transfer belt 8. Means.

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. In addition, a registration roller pair 28 is provided that adjusts the timing at which the transfer paper P delivered by the paper supply roller 27 is conveyed to the secondary transfer nip where the intermediate transfer belt 8 and the secondary transfer bias roller 19 face each other. 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).

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.
As shown in FIG. 3, the image forming unit 6 is a process cartridge that integrally supports the photoreceptor 1 and the developing device 5, and this process cartridge is detachable from the copying machine 500 main body. . In addition to the developing device 5, the image forming unit 6 includes a photoconductor cleaning device 2, a lubricant application device 41, and a charging device 40 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.

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, image information of each color of yellow, magenta, cyan, and black is transmitted to a writing unit (not shown). Then, laser light L based on the image information of each color is emitted from the writing unit toward the corresponding photoreceptor 1 (Y, M, C, K).

On the other hand, the four photoconductors 1 (Y, M, C, K) rotate in the clockwise direction in FIGS. 2 and 3, respectively. 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). Thus, 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 the irradiation position of the laser beam L.
In the writing unit, laser light L corresponding to the image signal is emitted from the 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 is scanned in the axial direction (main scanning direction) of the rotation axis of the yellow photoreceptor 1Y by a polygon mirror that rotates at high speed. Thus, an electrostatic latent image corresponding to the yellow component is formed on the surface of the yellow photoreceptor 1Y after being charged by the charging device 40.

  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).
The surface of the photoreceptor 1 (Y, M, C, K) after passing through the portion facing the developing device 5 reaches the 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, in 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 step). .

The surface of the photoconductor 1 after passing through the primary transfer nip reaches a position facing the photoconductor cleaning device 2. Then, untransferred toner remaining on the photosensitive member 1 is scraped and collected by the cleaning blade 2a at a position facing the photosensitive member cleaning device 2 (photosensitive member cleaning step).
The surface of the photoconductor 1 that has passed through the portion facing the photoconductor cleaning device 2 passes through a neutralization unit (not shown) to remove residual charges, and a series of image forming processes on the photoconductor 1 is completed. Prepare for image motion.

On the other hand, the respective color toner images on the four photoreceptors 1 (Y, M, C, K) are transferred in a superimposed manner, and the intermediate transfer belt 8 carrying the color toner images moves on the surface counterclockwise in FIG. Thus, it reaches the secondary transfer nip which is the position facing the secondary transfer bias roller 19.
Further, 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, and hits the registration roller pair 28. Stop once. The transfer paper P that has abutted against the registration roller pair 28 is conveyed toward the secondary transfer nip in accordance with the timing at which the color toner image formed on the intermediate transfer belt 8 moves toward the secondary transfer nip.
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).

  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 untransferred toner scraped off from the surface of the photoreceptor 1 by the cleaning blade 2a is accommodated in a waste toner storage container (not shown) through a recovery toner transport path (not shown). Further, untransferred toner scraped off from the surface of the intermediate transfer belt 8 by the intermediate transfer belt cleaning device and toner of a pattern image for process control also pass through a collected toner transport path (not shown) and a waste toner storage container (not shown). Is housed.

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.
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. 4 is a cross-sectional explanatory view of the developing device 5 of the present embodiment, and FIG. 5 is a perspective explanatory view of the developing device 5. The casing 58 of the developing device 5 includes a developing lower case 58a, a developing upper case 58b, a developing cover 58c, and a pre-developing case 58d.
The developing device 5 includes a developing roller 50 as a developer carrying member facing the photoreceptor 1, a supply screw 53 as a supply and conveyance member, a collection screw 54 as a collection and conveyance member, a doctor blade 52 as a developer regulating member, and A partition plate 57 is provided. The supply screw 53 and the recovery screw 54 are screw members provided with a spiral wing on the rotation shaft, and convey the developer in the axial direction of the rotation shaft by rotating. Further, a development region entrance seal 552 for preventing toner scattering may be disposed between the doctor portion where the doctor blade 52 faces the developing roller 50 and the development region.

  Of the space in the casing of the developing device 5, the supply conveyance path 53 a where the supply screw 53 is arranged and the collection conveyance path 54 a where the collection screw 54 is arranged are spatially partitioned by a partition plate 57. Further, the partition plate 57 has an end portion in a cross section orthogonal to the axial direction (cross section shown in FIG. 4) facing the surface of the developing roller 50 and is disposed close to the surface of the developing roller 50. It also functions as a separation plate that promotes the detachment of the developer G from above. Due to the function of the partition plate 57 as a separation plate, the developer G carried by the developing roller 50 and having passed through the developing region is prevented from reaching the supply conveyance path 53a, and is not delayed toward the collection conveyance path 54a. Can be moved.

The developing roller 50 includes a magnet roller 55 composed of a plurality of magnets fixed inside, and a developing sleeve 51 that rotates around the magnet roller 55. The developing sleeve 51 is a cylindrical member that includes a magnet roller 55 and is made of a rotatable nonmagnetic material. The magnet roller 55 of this embodiment includes a first magnetic pole P1 (N pole), a second magnetic pole P2 (S pole), a third magnetic pole P3 (N pole), a fourth magnetic pole P4 (N pole), as a plurality of magnetic poles. And the five magnetic poles of the 5th magnetic pole P5 (S pole) are provided. Note that P1 to P5 in FIG. 4 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 device 5 accommodates a two-component developer G (including a case where an additive or the like is added) composed of a toner and a carrier. A supply screw 53 and a recovery screw 54 are provided as a developer conveying member that conveys the developer G in the longitudinal direction (axial direction of the rotation axis of the developing sleeve 51) to form a circulation path. Further, in the developing device 5, the supply screw 53 and the collection screw 54 are arranged in the vertical direction, and the supply conveyance path 53 a and the collection conveyance path 54 a are separated by the partition plate 57 arranged between the supply screw 53 and the collection screw 54. Is formed.
Further, the amount of developer carried on the surface of the developing sleeve 51 on the upstream side in the surface movement direction of the developing sleeve 51 with respect to the developing area which is a facing portion between the photosensitive member 1 and the developing sleeve 51 is increased toward the developing area. A doctor blade 52 to be regulated is arranged below the developing roller 50.

Since the developing device 5 uses the two-component developer G, the toner is appropriately fed into the developing device 5 from the toner supply port 59 provided in a part of the developing device according to the toner consumption in the developing device 5. Is replenished.
Here, replenishment of new toner to the developing device 5 will be described. New toner filled in the toner container 11 is supplied to a toner hopper (not shown) disposed on the rear side of the copying machine 500 main body in FIG. 2 by a toner supply device (not shown) and stored in the toner hopper. When the toner stored in the toner hopper is judged to have a low toner concentration in the developing device 5 by a toner concentration detecting means (not shown) disposed in the developing device 5, the toner supply screw in the toner hopper is rotated. At this time, the toner replenishing screw is rotated for a time converted according to a predetermined conversion formula, and an appropriate amount of toner is supplied from the toner hopper to the toner replenishing port 59 of the developing device 5.

A toner detection sensor is disposed in the toner hopper. When the toner detection sensor detects that there is no toner at the detection position, a control unit (not shown) requests the toner supply device to supply the toner.
In response to this request, toner is supplied into the toner hopper by the toner replenishing device, and when the toner detection sensor detects that there is toner at the detection position, the toner supply by the toner replenishing device is stopped. On the other hand, if the toner detection sensor in the toner hopper does not detect the presence of toner at the detection position even if the control unit requests the toner supply device to supply the toner for a predetermined time, the control unit detects the toner in the toner container 11. Judge that there is no. Thereby, it can be detected that the toner remaining in the toner container 11 is exhausted.

  The toner replenished from the toner replenishing port 59 is agitated and mixed while being transported together with the developer G in the developing device 5 by the collection screw 54 and the supply screw 53 which are developer transport members. In this way, a part of the developer G stirred and mixed by the developer conveying member is supplied to the surface of the developing sleeve 51 which is a developer carrying member and is carried on the surface. The developer G carried on the surface of the developing sleeve 51 reaches the developing region after being regulated to an appropriate amount by the doctor blade 52 installed below the developing sleeve 51. In the developing area, the toner in the developer G on the surface of the developing sleeve 51 adheres to the latent image on the surface of the photoreceptor 1. A developing roller 51 constituting the developing roller 50 includes a magnet roller 55 in which a plurality of magnets are fixed. The magnet roller 55 includes a plurality of magnetic poles (P 1 to P 5) that form a magnetic field around the developing sleeve 51. ).

  In the developing device 5 of the present embodiment, a toner mainly composed of a polyester resin (average particle size 5.8 [μm]) and a carrier that is magnetic fine particles (average particle size 35 [μm]) are contained in the toner concentration. Is filled with 300 [g] of developer G uniformly mixed so as to be 7 [wt%]. Then, by rotating the supply screw 53 and the recovery screw 54 arranged in parallel at 600 [rpm], the conveyance of the developer G and the stirring of the new toner replenished from the toner replenishing port 59 are simultaneously performed. The toner and carrier are uniformly mixed and charged.

  The uniformly mixed developer G is transported in the longitudinal direction by a supply screw 53 provided in parallel in the vicinity of the developing sleeve 51 and developed by the magnetic force of the fifth magnetic pole P5 of the magnet roller 55 contained in the developing sleeve 51. It is delivered to the outer peripheral surface of the sleeve 51. The developer G transferred to the surface of the developing sleeve 51 reaches the developing region when the developing sleeve 51 rotates counterclockwise as indicated by an arrow in FIG. By applying a voltage to the developing sleeve 51 from a high voltage power source (not shown), a developing electric field is formed between the developing sleeve 51 and the photoreceptor 1 in the developing region. By this developing electric field, the toner in the developer G on the surface of the developing sleeve 51 is supplied to the latent image on the surface of the photoreceptor 1, and the latent image on the photoreceptor 1 is developed.

  The developer G on the surface of the developing sleeve 51 after passing through the developing region is collected in a collecting conveyance path 54 a in the developing device 5 as the developing sleeve 51 rotates. Specifically, the developer G detached from the surface of the developing sleeve 51 falls on the upper surface of the partition plate 57 and slides down, and is collected by the collecting screw 54.

FIG. 6 is a schematic diagram showing the movement of the developer G in the longitudinal direction in the developing device 5. A white arrow in FIG. 6 indicates the flow of the developer G in the developing device 5.
The partition plate 57 (not shown in FIG. 6) is provided with openings (71, 72) that connect the supply conveyance path 53a and the collection conveyance path 54a to both ends of the developing device 5 in the longitudinal direction. Then, the developer G that has reached the downstream end in the conveyance direction of the supply screw 53 in the supply conveyance path 53 a passes through the agent lifting port 72 in the opening provided in the partition plate 57, and is conveyed in the collection conveyance path 54 a. Delivered to the upstream end. On the other hand, the developer G that has reached the downstream end in the transport direction of the recovery screw 54 in the recovery transport path 54 a passes through the agent dropping port 71 in the opening provided in the partition plate 57 and is transported in the supply transport path 53 a. Delivered to the upstream end.

  In FIG. 6, for the sake of convenience of schematically showing the supply and recovery of the developer G to the developing sleeve 51, it is depicted that there is a certain distance between the supply transport path 53a and the recovery transport path 54a. However, the supply conveyance path 53a and the collection conveyance path 54a are partitioned by a plate-shaped partition plate 57 as shown in FIG. 4, and the agent lifting port 72 and the agent dropping port 71, which are the openings, are formed in a plate-shaped partition. It is a through-hole that penetrates the plate 57 from the front to the back.

  As shown in FIG. 6, the developer G in the supply conveyance path 53 a below the collection conveyance path 54 a is fed by the supply screw 53 along the axial direction (longitudinal direction) of the supply screw 53 on the right side in FIG. 6. It is conveyed toward. Further, while the developer G in the supply conveyance path 53a is conveyed to the supply screw 53, a certain amount is pumped to the surface of the developing sleeve 51 by the rotation of the supply screw 53 and the magnetic force of the fifth magnetic pole P5 as the pumping magnetic pole. . After being pumped up on the surface of the developing sleeve 51, the developer G on the surface of the developing sleeve 51 that has passed through the developing region is adjacent to the third magnetic pole P3 and the fourth magnetic pole P4, which are magnetic poles of the same polarity (N pole). The position of the agent separation magnetic pole constituted by is reached. Then, due to the action of the magnetic force of the agent separating magnetic pole and the action of the partition plate 57 as the separation plate, the separation sleeve 57 is separated from the surface of the developing sleeve 51 and sent into the collection conveyance path 54a.

The collection screw 54 in the collection conveyance path 54a above the supply conveyance path 53a removes the developer G separated from the developing sleeve 51 at the position of the agent separation magnetic pole in the axial direction of the collection screw 54 (conveyance direction by the supply screw 53). And in the longitudinal direction along the opposite direction).
A downstream side of the supply conveyance path 53 a that is a conveyance path by the supply screw 53 and an upstream side of the collection conveyance path 54 a that is a conveyance path by the collection screw 54 communicate with each other via the agent lifting port 72. The developer G that has not been pumped up from the supply conveyance path 53a to the developing roller 50 and has reached the downstream end of the supply conveyance path 53a remains in that position, and is pushed up by the developer G that is conveyed later, It reaches the upstream end of the collection conveyance path 54a.

  In addition, a toner replenishing port 59 is provided at the upstream end of the collection conveyance path 54a, and new toner is appropriately replenished from the toner container 11 to the toner replenishing port 59 via a toner replenishing device and a toner hopper (not shown). Is done. Further, the upstream end of the supply conveyance path 53 a and the downstream end of the recovery conveyance path 54 a communicate with each other via the agent dropping port 71. Then, the developer G that has reached the downstream end of the recovery transport path 54a falls by its own weight through the agent dropping port 71 and is delivered to the upstream end of the supply transport path 53a.

The developer G is transferred from the downstream end portion of the supply conveyance path 53a to the recovery conveyance path 54a, and further transferred from the downstream end portion of the recovery conveyance path 54a to the supply conveyance path 53a. Circulates in the developing device 5.
In the supply conveyance path 53a, the developer G is pumped up to the developing roller 50 while being conveyed to the supply screw 53, so that the amount of the developer G decreases as it goes downstream in the conveyance direction.
In the collection conveyance path 54a, the new toner and the developer G supplied from the toner supply port 59 are conveyed while being agitated by the collection screw 54. In the collection conveyance path 54a, the developer G that has passed through the development region and then separated from the surface of the developing sleeve 51 is collected and conveyed by the collection screw 54. Therefore, the developer G in the collection conveyance path 54a is downstream in the conveyance direction. Increase as you go to the side.

  In addition, a toner concentration sensor (not shown) serving as a toner concentration detection unit is disposed below the supply screw 53 in the supply conveyance path 53a or below the collection screw 54 in the collection conveyance path 54a. The toner density sensor measures the toner density in the developing device 5 as needed, and a control unit (not shown) controls the toner hopper so that the toner density falls within an appropriate value based on the measurement result.

  As described above, in the developing device 5, the supply screw 53 and the collection screw 54 rotate in the direction indicated by the arrow in FIG. 4, and at the same time, the magnetic force of the magnet roller 55 included in the developing sleeve 51 causes the developing sleeve 51 to move to the developing sleeve 51. Draw. Further, the developer sleeve 51 is rotated at a predetermined speed ratio with respect to the photosensitive member 1 so that the developer G is continuously pumped and supplied to the developing region. The developer G is detached from the developing sleeve 51 by forming a repulsive magnetic force at the agent separating magnetic pole constituted by the third magnetic pole P3 and the fourth magnetic pole P4. Then, the developer G carried to the section where the repulsive magnetic force is formed is released in the combined direction of the normal direction and the rotational tangential direction by the agent separating magnetic pole, and is recovered by dropping itself on the partition plate 57. The

Next, problems of the conventional developing device will be described.
Conventional development devices using the two-component development method such as the development device described in Patent Document 1 generally have two screws arranged horizontally and one of them facing the developing roller. The developing device is configured to cause the developer supply and recovery to proceed simultaneously between the developing roller and one screw (supply screw). The developing device having such a configuration is referred to as a horizontal biaxial circulation type, and this horizontal biaxial circulation type developing device is configured to supply developer to the developing roller and collect developer from the developing roller. With two screws. For this reason, when forming an image with a high image area ratio, there is a problem in that the toner density in the developer is lowered downstream of the developer conveyance of the screw that supplies the developer to the developing roller, and the image density is lowered. .

  As developing devices capable of solving such problems, there are developing devices described in Patent Documents 2 to 6 and the like. In these developing apparatuses, a supply conveyance path for supplying the developer to the developing roller while conveying the developer and a recovery conveyance path for collecting the developer on the surface of the developing roller that has passed through the development area while conveying the developer are spatially separated. It is formed so as to be separated. In this developing device, a developer conveying member includes a supply screw that conveys the developer in the supply conveyance path, and a recovery screw that conveys the developer in the recovery conveyance path. As described above, the developing device having the supply conveyance path and the recovery conveyance path separated from each other is supplied to the surface of the developing roller from the supply conveyance path, and the developer whose toner density has decreased after passing through the development region is transferred to the collection conveyance path. To be recovered. This configuration is a so-called one-way circulating conveyance developing device in which the developer supplied from the supply conveyance path to the developing roller is not returned to the supply conveyance path but is transferred to the collection conveyance path. The developer is separately supplied to and collected from the developing roller, and the developer having a reduced toner concentration is not delivered to the supply conveyance path and is not used for development. The density deviation of the developed toner image can be reduced.

  In the developing device described in Patent Document 2, the supply conveyance path is arranged above the collection conveyance path, and the doctor blade is arranged above the development roller. The developer is transported from the supply transport path disposed above to the developing roller, and then transported through the recovery transport path disposed below. In such a configuration, the forward development is performed when the transfer unit is disposed below the developing device or the photosensitive member, and the reverse development is performed when the transfer unit is disposed above. May be a restriction. Further, in order to lift the developer from the lower recovery transport path to the upper supply transport path, the developer pressure at the downstream end in the transport direction of the recovery transport path through which all the circulating developer passes. The developer is stressed.

  On the other hand, in the developing devices described in Patent Documents 3 to 6, the doctor blade is disposed below the developing roller. In this configuration, the developer is transported from the supply transport path disposed below to the developing roller, and then transported to the collection transport path disposed above. The developer transported in the recovery transport path by the recovery screw and reaches the downstream end of the recovery transport path in the transport direction is dropped by its own weight and transferred to the supply transport path. With such a configuration, unlike the configuration in which the supply conveyance path is arranged above, it is not necessary to increase the developer pressure at the transfer section at the downstream end in the half direction of the collection conveyance path, and the stress on the developer Can be reduced.

  However, in the developing devices described in Patent Document 3 and Patent Document 4, the developer in the collection conveyance path reaches a position higher than the tip of the partition member that spatially partitions the supply conveyance path and the collection conveyance path. It is a configuration. In such a configuration, the developer accumulated in the collection conveyance path flows into the supply conveyance path below from the gap between the partition member and the developing roller, and one-way circulation is not established. If the unidirectional circulation is not established, the developer that has passed through the developing area is reattached to the surface of the developing roller immediately after being separated from the developing roller, and is conveyed to the developing area, resulting in an image density reduction or density unevenness image. There is a risk. In the unidirectional circulation configuration, the developer in the collection conveyance path tends to gradually increase in volume toward the downstream side in the conveyance direction, so that the above-described image defects are more likely to occur toward the downstream side in the conveyance direction of the collection conveyance path. .

  In the developing devices described in Patent Documents 5 and 6, the leading end portion of the partition member that spatially partitions the supply transport path and the recovery transport path is set at a higher position than the configurations described in Patent Document and Patent Document 4. . As a result, it is possible to prevent the developer from getting over the front end of the partition member in the collection conveyance path and leaking into the supply conveyance path.

  On the other hand, in order to prevent the developer from sticking to the developing roller during storage of the developer, the developing device, the process cartridge including the developing device, the copying machine, and the printer, many developing devices including an easy peel sheet member have been proposed. (For example, Patent Document 1). However, a configuration in which an easy-peel sheet member that shields the developer and the developing roller in the developer transport path is provided in a one-way circulation developing device is not in practice. This is for the following reason.

  The integrated supply / recovery system, in which two screws are horizontally arranged and the supply and recovery of the developer is performed in one developer transport path in which one screw is arranged, is performed between the developer roller and the developer roller. What is necessary is just to shield between the developing agent conveyance path which performs transfer, and a developing roller. That is, since there is only one opening for transferring the developer between the developing roller and the developer conveying path, it is easy to arrange a sheet member that shields the opening. On the other hand, in a supply / recovery separation type developing device in which the supply conveyance path and the recovery conveyance path are separated as in one-way circulation, the developer conveyance path between the supply conveyance path and the collection conveyance path and the developing roller are separated. Then, the developer is transferred through the respective openings. For this reason, it is necessary to shield each of the two openings, and if it is intended to shield with one sheet member, it covers a plurality of openings, making it difficult to arrange the sheet members.

Further, the supply / collection integrated type developing device has a space above the developer conveyance path on which the developer is not transferred to and from the developing roller, and an initial developer for storing the initial developer before use in this space. A configuration in which a developer container is disposed is conceivable. In such a configuration, the sheet member is arranged in the opening between the developer conveyance path and the initial developer container, and the sheet member can be removed during use, so that the developer is dropped by gravity and developed. The developer is filled in the agent conveyance path.
On the other hand, if the initial developer container is arranged above the collection conveyance path of the developing apparatus in which the collection conveyance path is arranged above the supply conveyance path in the supply / recovery separation system, the image forming apparatus is very small in the height direction. It becomes difficult to. This is because the upper part of the supply / recovery separation type developing device with the recovery conveyance path disposed above is a transfer provided with an intermediate transfer belt and the like so as to span a plurality of developing devices and photosensitive members so as to be compact in layout. This is because there are many configurations in which the apparatus is arranged horizontally.

Next, features of the present invention will be described.
FIG. 1 is an explanatory cross-sectional view of the developing device 5 before use such as when shipped from a factory, and FIG. 7 is a perspective view showing a part of the developing device of the developing device 5 before use in a sectional view.
As shown in FIGS. 1 and 5, the developing device 5 is disposed such that the doctor blade 52 faces the lower side of the developing roller 50, and the developer G is accommodated in the supply conveyance path 53a and the collection conveyance path 54a. ing.
Then, a supply opening 53b that communicates between the developing roller 50 and the inside of the supply conveyance path 53a and a shielding sheet 70 that shields the collection opening 54b that communicates between the development roller 50 and the inside of the collection conveyance path 54a are provided. Prepare. The shielding sheet 70 can be removed from the developing device 5 by being pulled out from the upper end portion 70b side by a user or the like.

In a state where the shielding sheet 70 is attached, a doctor gap that is a gap between the doctor blade 52 and the developing roller 50 is shielded on the lower end portion 70a side of the shielding sheet 70 in a cross section orthogonal to the axial direction (the cross section shown in FIG. 1). It arrange | positions so that the sheet | seat 70 may pass. The lower end portion 70a of the shielding sheet 70 is located outside the doctor gap, and the lower end portion 70a is disposed so as to overlap the front end portion of the development area inlet seal 552 as shown in FIG. .
Further, on the upper end portion 70 b side of the shielding sheet 70, the shielding sheet 70 is disposed so as to pass through a cover opening 580 provided in the developing cover 58 c which is a portion above the collection conveyance path 54 a of the casing 58. The upper end portion 70b of the shielding sheet 70 is positioned outside the developing cover 58c. As shown in FIG. 1, a part of the shielding sheet 70 on the upper end portion 70b side serves as a sheet bonding portion 70c. It is bonded and fixed to the upper surface of 58c.

  In the axial direction, the shielding sheet 70 shields a region β where the supply conveyance path 53 a faces the developing roller 50 and a region α where the collection conveyance path 54 a faces the developing roller 50. It is arranged extending in the axial direction. In addition, the cover opening 580 is formed over the entire longitudinal direction of the developing device 5 in accordance with the width (length in the axial direction) of the shielding sheet 70 so that the shielding sheet 70 that shields the regions α and β can pass therethrough. It is formed across.

  Further, since the toner replenishing port 59 is opened in the developing device 5, a shutter member or a cap member (not shown) is provided so as to close the toner replenishing port 59 in a state before use such as at the time of shipment. The shutter member or the cap member is removed from the toner supply port 59 automatically or manually when the developing device 5 is mounted on the copying machine 500 main body.

  As shown in FIG. 1, the shielding sheet 70 passes from the outside of the casing 58 of the developing device 5 through the doctor gap, through the gap between the partition plate 57 and the developing roller 50, and from the cover opening 580 provided in the developing cover 58c. It slips out of the casing 58. The supply opening 53b and the collection opening 54b can be closed by the shielding sheet 70 arranged so as to pass through such a path, and the developer G in the developing device 5 is supplied to the supply conveyance path 53a or the collection conveyance. The developing roller 50 is shielded while being stored in the path 54a.

Since the developer G cannot pass through the shielding sheet 70, the lower end of the developer G in the supply conveyance path 53 a and the collection conveyance path 54 a reaches the opposite space across the shielding sheet 70. It is necessary to wrap around from the outside of 70a or the lower end 70a.
On the lower end portion 70 a side of the shielding sheet 70, the shielding sheet 70 is arranged so that the shielding sheet 70 passes through, and the lower end portion 70 a of the shielding sheet 70 is positioned outside the doctor gap. Therefore, the developer G in the supply conveyance path 53a or the collection conveyance path 54a needs to pass through the doctor gap in order to go around from the outside of the lower end portion 70a of the shielding sheet 70. The doctor gap is a gap that allows the developer G held on the surface of the developing roller 50 by the magnetic force of the magnet roller 55 to pass along with the rotating developing sleeve 51 during the image forming operation. For this reason, the developer G that is not carried on the developing sleeve 51 hardly passes. Therefore, in the developing device 5 of the present embodiment, the developer G wraps around from the outside of the lower end portion 70 a of the shielding sheet 70 to the surface of the developing roller 50 without bonding the shielding sheet 70 to the casing 58. It can be prevented from reaching.

  Further, on the upper end portion 70b side of the shielding sheet 70, the shielding sheet 70 is disposed so as to pass through a cover opening 580 provided in the developing cover 58c, and the upper end portion 70b is positioned outside the developing cover 58c. . Therefore, the developer G in the supply conveyance path 53a and the collection conveyance path 54a needs to pass through the cover opening 580 in order to go around from the outside of the upper end portion 70b of the shielding sheet 70. Since the cover opening 580 is positioned above the collection conveyance path 54a disposed above the supply conveyance path 53a, some external force is applied to the developer G, and the developer G does not move upward against gravity. And the cover opening 580 cannot pass. In a state where the shielding sheet 70 is attached, the supply screw 53 and the collection screw 54 that apply the conveyance force to the developer G in the supply conveyance path 53a and the collection conveyance path 54a are not driven. Therefore, since there is little opportunity for external force to be applied to the developer G, it is difficult for the developer G to pass through the cover opening 580.

  Even if the developer G passes through the cover opening 580, the developer G is leaked because it is outside the casing 58 of the developing device 5, so that the developer G leaks. Reaching the surface of the roller 50 can be prevented. Therefore, even if the shielding sheet 70 is not bonded to the casing 58, the developer G can be prevented from wrapping around from the outside of the upper end portion 70b of the shielding sheet 70 and reaching the surface of the developing roller 50. Further, the problem that the developer G leaks out can be easily solved by providing the cover filter 523 so as to close the gap between the edge of the casing 58 forming the cover opening 580 and the shielding sheet 70. is there.

For both the lower end portion 70 a and the upper end portion 70 b of the shielding sheet 70, the developer G wraps around from the outside of the end portion of the shielding sheet 70 to the developing roller 50 without bonding the shielding sheet 70 to the casing 58. It can be prevented from reaching. Since no adhesion is required, it is not necessary to secure a margin for adhesion to the casing 58, and a developer passage opening having a wide opening range and a complicated shape, such as the supply opening 53b and the collection opening 54b. Even if it exists, it can shield with the shielding sheet 70. FIG. By this shielding, it is possible to prevent the developer G in the developer conveyance path, which is the supply conveyance path 53a and the collection conveyance path 54a, from contacting the developing roller 50 before use. Further, since the developer G is stored in the developer transport path, it is not necessary to provide a space for storing the initial developer different from the developer transport path as in the above-described initial developer container. The enlargement of the apparatus can be prevented.
As described above, in the developing device 5 of the present embodiment, it is possible to prevent the developer G from coming into contact with the developing roller 50 in a state before use while preventing an increase in size of the device.

In the copying machine 500, when image formation is performed with the developer G fixed to the developing roller 50, there is a risk of image failure. In this embodiment, since the developer G can be prevented from coming into contact with the developing roller 50 of the developing device 5 before use, image defects caused by the developer G sticking to the developing roller 50 before use are prevented. Can be prevented.
Further, the developing device 5 of the present embodiment is detachable as the image forming unit 6 from the copying machine 500 main body, and when the image forming unit 6 is replaced, the shielding sheet 70 provided in the developing device 5 is pulled out. Mounted on the copying machine 500 main body. Thereby, it is possible to prevent the developer G from adhering to the developing roller 50 provided in the developing device 5 before use when the image forming unit 6 is stored or transported.

In the developing device 5 of the present embodiment, polyurethane is used as the material of the shielding sheet 70, but is not limited thereto.
In the present embodiment, the invention in which the sheet member such as the shielding sheet 70 is arranged from the doctor gap to the casing above the developer conveyance path is applied to a biaxial one-way circulation developing device. The developing device to which the arrangement of the sheet member which is a characteristic configuration of the present invention is applied is not limited to the biaxial developing device, but a triaxial type like the developing device described in Patent Document 5. You may apply to the developing device of direction circulation.

  Further, like the developing device described in Patent Document 1, the present invention can also be applied to a developing device of an integrated supply and recovery system. In the developing device described in Patent Document 1, there is one opening to be shielded by the sheet member, and the sheet member is shielded by adhering to the casing. However, by disposing the sheet member from the doctor gap to the casing above the developer conveyance path as in the present invention, the process of adhering the sheet member to the casing becomes unnecessary, simplifying the manufacturing process, and freedom of layout There are advantages such as improvement.

  When applied to a biaxial unidirectional circulation developing device such as the developing device 5 of the present embodiment, the toner image has a density deviation in the axial direction as compared to a supply and recovery integrated developing device. It can be prevented from occurring. In addition, space can be saved in the horizontal direction as compared with a three-axis one-way circulation developing device.

  Further, the developing device 5 has a function as an opening sealing member for sealing the cover opening 580 provided in the developing cover 58c so that the developer G does not pass through, and a cover in which a gap through which air can pass is formed. A filter 523 is provided. In the state where the shielding sheet 70 is attached, the cover filter 523 is contracted. When the shielding sheet 70 is removed, the cover filter 523 expands by the thickness of the shielding sheet 70 and the cover opening 580 is sealed, so that the developer G, in particular, toner with small particles does not leak out of the casing 58. . Furthermore, since the air can pass through the cover filter 523, the air escapes through the cover filter 523 even if the air pressure increases due to the temperature of the air in the casing 58 rising due to driving heat of the developing device 5 or the like. The fluctuation of the atmospheric pressure in the casing 58 can be suppressed. By suppressing the fluctuation of the atmospheric pressure in the casing 58, it is possible to prevent the atmospheric pressure in the casing 58 from rising. Thereby, it is possible to prevent the toner from being blown out from the gap between the surface of the developing roller 50 and the casing 58 or the gap between the casings 58 due to the increase in the atmospheric pressure in the casing 58.

In the developing device 5, the cover filter 523 is disposed on the opposite side of the developing roller 50 with the shielding sheet 70 interposed therebetween, that is, on the collection conveyance path 54 a side. Since the shielding sheet 70 prevents the developer conveyance path 53a and the developer G in the supply conveyance path 53a from reaching the developing roller 50, the surface of the shielding sheet 70 opposite to the developing roller 50 is the developer. G may adhere. If the shielding sheet 70 with the developer G adhered thereto is removed from the developing device 5, the developer G may be scattered.
On the other hand, in the developing device 5, the cover filter 523 is disposed on the opposite side of the developing roller 50 with the shielding sheet 70 interposed therebetween, and contacts the surface to which the developer G may adhere. With such a configuration, when the shielding sheet 70 is pulled out from the developing device 5, the developer G adhering to the surface of the shielding sheet 70 opposite to the developing roller 50 is wiped off by the cover filter 523. Thereby, it is possible to prevent the developer G from scattering.
By sealing the cover opening 580 with the cover filter 523, it is not necessary to separately provide a member that shields the cover opening 580 or a member that cleans the shielding sheet 70 while suppressing an increase in the atmospheric pressure in the casing 58. Cost reduction can be achieved.

  FIG. 8 is an explanatory cross-sectional view of the vicinity of the end portion in the axial direction of the developing device 5 before use. As shown in FIGS. 7 and 8, a side seal 570 is provided near the end in the axial direction of the developing device 5 so as to close the gap between the surface of the developing roller 50 and the casing 58. Although the side seal 570 can also be confirmed in the cross section shown in FIG. 1, the side seal 570 is not shown in FIG. 1 in order to prevent the drawing from becoming complicated.

  The side seal 570 is a plastic seal member made of sponge or the like. The developing device 5 has a developing cover 58 c above the developing roller 50, and a side seal 570 is disposed so as to close a gap like a cylindrical part between the developing cover 58 c and the developing roller 50. Yes. Further, at the position where the side seal 570 is provided, it is outside the axial ends of the supply transport path 53a and the recovery transport path 54a, and the casing 58 is a wall surface at the end in the axial direction of the supply transport path 53a and the recovery transport path 54a. Is forming. The portion of the casing 58 that forms the wall surface has a shape that avoids the end portion in the axial direction of the developing roller 50, and a part of the cylindrical shape is also formed between the casing 58 that forms the wall surface and the developing roller 50. A gap having a shape like this is formed. That is, a gap in the shape of a part of a cylindrical shape having a “C” shape in the cross section shown in FIG. 8 is formed between the casing 58 at the axial end and the surface of the developing roller 50. The side seal 570 is disposed so as to close the “C” -shaped space.

Further, as shown in FIG. 8, the side seal 570 is provided with a slit portion 570 a that obliquely penetrates from the inside of the “C” shape to the outside in the vicinity of the position facing the partition plate 57. As shown in FIG. 8, in the range from the doctor gap to the vicinity of the position where the tip of the partition plate 57 faces the developing roller 50, the end portion in the axial direction of the shielding sheet 70 is between the side seal 570 and the surface of the developing roller 50. It is sandwiched between. The shielding sheet 70 passes through the slit portion 570 a near the position where the front end of the partition plate 57 faces the developing roller 50, exits to the “C” -shaped outside of the side seal 570, and covers the opening 580. From the casing 58 to the outside.
In a portion where the axial end portion of the shielding sheet 70 is sandwiched between the side seal 570 and the surface of the developing roller 50, the developer G wraps around from the outside of the axial end portion of the shielding sheet 70 and the developing roller 50. Can be prevented from reaching the surface.

The configuration for removing the shielding sheet 70 from the developing device 5 is not limited to a configuration in which a user or the like pulls out, and a configuration in which the shield sheet 70 is automatically wound up may be employed. FIG. 9 is an explanatory cross-sectional view of the developing device 5 including the sheet winding device 525 that winds the shielding sheet 70 before use.
In a state where the developing device 5 shown in FIG. 9 is mounted on the copying machine 500 main body, the take-up shaft 525a rotates in the direction of the arrow γ in FIG. As a result, the shielding sheet 70 is automatically wound up, and the developing device 5 can supply the developer G to the developing roller 50.
The sheet winding device 525 is driven by a driving source (not shown) provided in the copying machine 500 main body, and automatically stops after driving for a predetermined time required for winding.

In the developing device 5 shown in FIG. 1, when the developing device 5 or the image forming unit 6 as a process cartridge is transported alone, the shield sheet 70 is pulled out of the apparatus and set in the copying machine 500 main body. Is completed. However, in order to remove the shielding sheet 70 from the developing device 5 and the image forming unit 6 in which the shielding sheet 70 is set in the copying machine 500, it is necessary to remove the developing device 5 and the image forming unit 6 from the copying machine 500 once. Yes, it takes time.
On the other hand, in the developing device 5 shown in FIG. 9, since the sheet winding device 525 automatically winds the shielding sheet 70, the shielding sheet 70 (preset seal) is removed without removing the developing device 5 from the copying machine 500. Can do. For this reason, it is possible to save the work of the user by omitting the manual operation of the user at the time of setup before using the developing device 5.

As the developing device 5, a guide surface for guiding the shielding sheet 70 may be provided in the casing 58. Hereinafter, the developing device 5 having a configuration including the sheet guide surface 58e for guiding the shielding sheet 70 will be described with reference to FIGS.
FIG. 10 is an explanatory view showing a state in which the shielding sheet 70 is removed by the developing device 5 having the sheet guide surface 58e. FIG. 10A is a perspective explanatory view of an end portion in the axial direction of the developing device 5, and FIG. 10B is an enlarged explanatory view of a region η in FIG. FIG. 11 is a perspective explanatory view of the end portion in the axial direction in a state where the shielding sheet 70 is attached by the developing device 5 having the sheet guide surface 58e. 10 and 11, the developing cover 58c and the developing region entrance seal 552 are omitted.

As shown in FIG. 1 and the like, a gap of 0.1 to 0.6 [mm] is formed between the front end surface 57a of the partition plate 57 (see FIGS. 10 and 11) and the surface of the developing roller 50. Thus, the partition plate 57 is arranged so as not to contact the developing roller 50.
In the developing device 5 shown in FIGS. 10 and 11, the sheet guide surface 58e is formed to be a continuous surface with the front end surface 57a. By moving the shielding sheet 70 while being guided by the sheet guide surface 58e, the shielding sheet 70 can be prevented from being deformed by twisting or wrinkling, and is excellent in the space between the developing roller 50 and the developer G. Can be obtained.

  In the developing device 5 shown in FIGS. 10 and 11, a portion of the sheet guide surface 58e above the front end surface 57a is formed to extend vertically from the front end surface 57a. Further, a portion of the sheet guide surface 58e below the front end surface 57a has a shape along the surface of the developing roller 50 while maintaining the same distance as the distance between the front end surface 57a and the surface of the developing roller 50. That is, the sheet guide surface 58e extends from the position of the front end surface 57a to the position where the doctor blade 52 is disposed, so that the distance from the surface of the developing roller 50 matches the distance between the front end surface 57a and the surface of the developing roller 50. Thus, the shape is along the surface of the developing roller 50.

The doctor gap of the developing device 5 is normally set by adjusting at the time of fitting. Specifically, adjustment work is required in which the developing roller 50 and the doctor blade 52 are arranged in the developing device 5, a certain gap such as a gap gauge is set, and fixed with a screw or the like. In this case, it is difficult to perform the adjustment operation with the shielding sheet 70 sandwiched between the doctor gaps.
In the developing device 5 having the sheet guide surface 58e for such a problem, the shielding sheet 70 can be inserted from the doctor gap side or the cover opening 580 side after performing the adjustment work. Specifically, the shielding sheet 70 inserted from one opening of the doctor gap or the cover opening 580 is guided along the sheet guide surface 58e, so that the other opening does not occur without twisting or wrinkling. Can reach up to. Thereby, since the supply opening 53b and the collection opening 54b can be shielded, it is possible to realize a configuration in which the shielding sheet 70 can be disposed after the doctor gap adjustment work.

  In the developing device 5 of the present embodiment, the shielding sheet 70 is removed from the developing device 5 by pulling one of the end portions in the cross section orthogonal to the axial direction, that is, the lower end portion 70a or the upper end portion 70b. Yes. The drawing direction of the shielding sheet 70 in the developing device 5 configured to arrange the shielding sheet 70 across the doctor gap from the cover opening 580 may be a direction parallel to the axial direction. However, in the case of a configuration that is pulled out in a direction parallel to the axial direction, it is necessary to provide an opening for pulling out the shielding sheet 70 on the side surface of the casing, and it is difficult to maintain the strength of the casing 58. On the other hand, if it is the structure which pulls the lower end part 70a or the upper end part 70b of the shielding sheet 70, it is not necessary to provide a new opening part for drawing out the shielding sheet 70 other than the cover opening part 580 and the doctor gap, and the casing. It can suppress that the intensity | strength of falls.

  Further, in the developing device 5 of this embodiment, the shielding sheet 70 is configured to remove the shielding sheet 70 from the cover opening 580 by pulling the upper end portion 70b. When removing the shielding sheet 70 from the developing device 5, the shielding sheet 70 is pulled out with the unit including the developing device 5 removed from the copying machine 500 main body. At this time, in the case of a configuration in which a process cartridge that integrally supports the developing device 5 and the photosensitive member 1 is formed, if an attempt is made to pull out from the lower end portion 70a side that is the end portion on the doctor gap side of the shielding sheet 70, Such a problem may occur. That is, when the drawing operation is performed on the side close to the photosensitive member 1, the operator's hand or the shielding sheet 70 may come into contact with the photosensitive member 1 and the surface of the photosensitive member 1 may be damaged. On the other hand, as in the present embodiment, the upper end portion 70b, which is the end portion opposite to the doctor gap, is pulled, so that the surface of the photoreceptor 1 is prevented from being damaged, and the shielding sheet 70 is protected from the cover opening 580. Good operability when pulling out can be obtained.

  FIG. 12 shows that the position of the cover opening 580 is closer to the developing roller 50 than the developing device 5 shown in FIG. 1 and the cover filter 523 is located on the developing roller 50 side with respect to the shielding sheet 70 before use. FIG. The cover filter 523 is an opening sealing member that allows passage of air and prevents passage of the developer G so as to prevent an increase in internal pressure in the developing device 5 during image formation.

In the developing device 5 shown in FIG. 12, since the cover filter 523 is positioned on the developing roller 50 side with respect to the shielding sheet 70, the developer in the supply conveyance path 53a and the collection conveyance path 54a when the shielding sheet 70 is attached. G does not contact the cover filter 523. When the developer G can come into contact with the cover filter 523 with the shielding sheet 70 attached, the developer G comes into contact with the cover filter 523 before using the developing device 5 during transportation or storage. May cause clogging.
On the other hand, in the developing device 5 shown in FIG. 12, the developer G in the supply conveyance path 53a and the collection conveyance path 54a does not contact the cover filter 523 in a state where the shielding sheet 70 is attached. It is possible to prevent clogging from occurring in the cover filter 523 before use.

Further, the developing device 5 shown in FIG. 12 includes a sheet cleaning member 524 for wiping off the developer G adhering to the surface of the shielding sheet 70 opposite to the developing roller 50. In the developing device 5 shown in FIG. 12, since the cover filter 523 is disposed on the developing roller 50 side with respect to the shielding sheet 70, the developer G attached to the surface of the shielding sheet 70 opposite to the developing roller 50 is removed. The cover filter 523 cannot be wiped off. However, since the developer G adhering to the shielding sheet 70 can be wiped off by the sheet cleaning member 524, the developer G can be prevented from scattering.
The arrangement of the sheet cleaning member 524 may be outside the developing cover 58c as shown by a solid line in FIG. 12, or may be inside the developing cover 58c as shown by a broken line in FIG.

[Modification 1]
Next, the cover filter 523 is not disposed in the cover opening 580 through which the shielding sheet 70 is passed, the sheet cleaning member 524 is disposed, and after the shielding sheet 70 is pulled out, the cover opening 580 is closed by the sheet cleaning member 524. Example 1 will be described.
FIG. 13 is an explanatory cross-sectional view of the developing device 5 of Modification 1. FIG. 14 is an enlarged cross-sectional view of the vicinity of the sheet cleaning member 524 of the developing device 5 shown in FIG. An arrow A in FIG. 14 indicates the drawing direction of the shielding sheet 70.
As shown in FIG. 13, in the developing device 5 of the first modification, a pressure release opening 581 is provided in the development cover 58 c separately from the cover opening 580, and a cover filter 523 is provided in the pressure release opening 581. .

  The developing device 5 of Modification 1 includes a first sheet cleaning member 524a and a second sheet cleaning member 524b on the developing roller 50 side with the shielding sheet 70 interposed therebetween as the sheet cleaning member 524. The two sheet cleaning members 524 are disposed in a portion of the developing cover 58c where the cover opening 580 is formed, and the surface of the shielding sheet 70 is pulled when the shielding sheet 70 is pulled upward and passes through the cover opening 580. Clean by touching.

  Two sheet cleaning members 524 are arranged so as to sandwich the shielding sheet 70, and are plate-like members made of an elastic material that are bonded to the developing cover 58c by the bonding surface 535. The two sheet cleaning members 524 facing each other with the shielding sheet 70 in between are flat plate-shaped elastic members. As shown in FIG. 14, the sheet cleaning member 524 is disposed on the developing cover 58c by the adhesive surface 535 extending in the horizontal direction, and bends in an L shape at the position of the cover opening 580 provided in the developing cover 58c. The free end side is arranged so as to extend vertically upward. Further, the two sheet cleaning members 524 are arranged so as to be pressed against each other by a restoring force for returning to the flat plate shape from the bent state in the L shape.

  The direction in which the two sheet cleaning members 524 are bent is the drawing direction of the shielding sheet 70 indicated by the arrow A in FIG. 14, and the free end side of the sheet cleaning member 524 protrudes from the developing cover 58c in the pulling direction. Yes.

In the case of a configuration in which the shielding sheet 70 is pulled out from the upper portion of the casing 58 as in the developing device 5 illustrated in FIG. 1, the following problem may occur.
When the shielding sheet 70 is pulled out, an upward force acts on the developing cover 58c by the frictional force between the developing cover 58c constituting the upper portion of the casing 58 and the shielding sheet 70, and the central portion in the axial direction of the developing cover 58c. The developing cover 58c is deformed so as to be lifted. As a result, the member for cleaning the surface of the shielding sheet 70 fixed in the vicinity of the cover opening 580 of the developing cover 58c ("cover filter 523" in FIG. 1 and "sheet cleaning member 524" in FIG. 12) is also deformed. When the member that cleans the surface of the shielding sheet 70 is deformed, a part of the shielding sheet 70 and the member to be cleaned is not in contact with each other, and the entire axial direction of the shielding sheet 70 cannot be cleaned.

Further, in order to clean the entire axial direction of the shielding sheet 70, it is conceivable to increase the pressing force of the member to be cleaned against the shielding sheet 70. However, when the pressing force is increased, the above-described frictional force is increased, and a member to be cleaned installed near the cover opening 580 is deformed. As a result, the entire axial direction of the shielding sheet 70 cannot be cleaned.
Further, when deformation occurs in the portion of the developing cover 58 c that forms the cover opening 580, a gap is generated after the shielding sheet 70 is pulled out, and the developer G inside the casing 58 may be scattered outside the casing 58.

  Patent Document 7 discloses a toner wiping member installed in the developing device for the purpose of wiping off the developer attached to the sheet member. The developing device described in Patent Document 7 is similar to the developing device of Modification 1 in that the developer attached to the sheet member is wiped off by a cleaning member installed in the developing device. However, when the sheet member is pulled out from the upper part of the developing device, the problem that the entire surface of the sheet member cannot be cleaned due to deformation near the opening of the casing cannot be solved. Furthermore, the developing device described in Patent Document 7 is based on the premise that the sheet member is pulled out in the axial direction. In this case, the amount of deformation near the opening of the casing is relatively small, so that poor cleaning is unlikely to occur. . However, in the one-way circulation type developing device as shown in FIG. 1 and the like, it is difficult to pull out the sheet member from the end portion in the axial direction with a small deformation amount due to layout limitations. Therefore, it is necessary to install an opening for pulling out the sheet member in another part, that is, a part constituting the wall surface parallel to the axial direction, and such an opening is long in the axial direction and forms the opening. The casing of the part is likely to be deformed.

  On the other hand, in the developing device 5 of the first modified example, even when the developing cover 58c is deformed when the shielding sheet 70 is pulled out, the developing device 5 at the portion where the deformation that causes a gap with the shielding sheet 70 occurs. Both or one of the two sheet cleaning members 524 fall toward the other. As a result, even if the developing cover 58c is deformed, the gap can be filled, the state where the shielding sheet 70 is sandwiched between the two sheet cleaning members 524 can be maintained, and the sheet cleaning member 524 can be maintained over the entire axial direction. The contact state with respect to the shielding sheet 70 can be maintained. Therefore, the developer G adhering to the shielding sheet 70 can be cleaned evenly.

Further, as described above, the free end sides of the two sheet cleaning members 524 extend in the drawing direction. Further, they are arranged so as to push each other with a restoring force to return to a flat plate shape. With these configurations, the two sheet cleaning members 524 fall over each other with respect to the gap generated after the shielding sheet 70 is pulled out, and the gap can be filled. Therefore, it is possible to prevent the developer G from leaking out from the cover opening 580 after the shielding sheet 70 is pulled out.
As the sheet cleaning member 524, various materials generally used as a sealing material for sealing, such as polyurethane, can be used. However, even a material used as a sealing material, such as UBT, has a low resistance to rubbing and wears when the shielding sheet 70 is pulled out, and there is a possibility that a gap may be formed after the shielding sheet 70 is pulled out. It is desirable not to use it.

  As in the first modification, the two sheet cleaning members 524 are arranged so as to be bent in an L shape. As shown in FIG. 14, the free end side of the sheet cleaning member 524 extends in the pulling direction from the developing cover 58c. The configuration is not limited to the protruding configuration. As shown in FIG. 15, even if the free end of the sheet cleaning member 524 does not protrude from the developing cover 58c, the free end of the sheet cleaning member 524 protrudes in the pulling direction of the shielding sheet 70 from the adhesive surface 535. If it is. With such a configuration, the two sheet cleaning members 524 are pressed against each other with a restoring force to return to the flat plate shape from the bent state, and the gap can be filled even if the developing cover 58c is deformed.

  In the configuration in which the shielding sheet 70 is sandwiched between the two sheet cleaning members 524 as in Modification 1, the materials of the first sheet cleaning member 524a and the second sheet cleaning member 524b may be different. In this case, it is desirable that the first sheet cleaning member 524a is made of a material having good sliding properties with respect to the shielding sheet 70, and the second sheet cleaning member 524b is made of a material having good cleaning properties with respect to the shielding sheet 70. The surface of the shielding sheet 70 on the side where the first sheet cleaning member 524a contacts is the surface facing the developing roller 50 and does not contact the developer G. Therefore, it is not necessary to clean the surface when pulling out. . Then, by using a material that places importance on slidability, the sliding load when the shielding sheet 70 is pulled out can be reduced, and the operability can be improved.

  On the other hand, since the surface of the shielding sheet 70 on the side where the second sheet cleaning member 524b comes into contact is in contact with the developer G, it is required to clean the surface reliably when the sheet is pulled out. By using a material that emphasizes cleaning properties for the second sheet cleaning member 524b, the developer G adhering to the shielding sheet 70 can be more reliably removed, and scattering of the developer G can be more reliably prevented.

[Modification 2]
Next, modified example 2 in which the mounting angle of the sheet cleaning member 524 with respect to the developing cover 58c is different from modified example 1 will be described.
FIG. 16 is an enlarged cross-sectional view of the vicinity of the sheet cleaning member 524 of the developing device 5 of Modification 2. An arrow A in FIG. 16 indicates the drawing direction of the shielding sheet 70.
In the second modification, two sheet cleaning members 524 are disposed opposite to the developing cover 58c, and the shielding sheet 70 is configured to pass between the two sheet cleaning members 524.

  In the second modification, an adhesive surface 535 having a gradient is provided in the vicinity of the cover opening 580 of the developing cover 58c, and the two sheet cleaning members 524 are fixed to the developing cover 58c by the adhesive surface 535. The two sheet cleaning members 524 are arranged so as to bend more gently than the L shape at the position of the cover opening 580 provided in the developing cover 58c, and the free end side thereof extends vertically upward. Further, the two sheet cleaning members 524 are arranged so as to be pressed against each other by a restoring force for returning to a flat plate shape from the bent state. Further, the direction in which the two sheet cleaning members 524 are bent is the drawing direction of the shielding sheet 70 indicated by the arrow A in FIG. 16, and the free end side of the sheet cleaning member 524 protrudes from the developing cover 58c in the drawing direction. It has become.

In the second modification, the sheet cleaning member 524 is fixed by the adhesive surface 535 having a gradient, and the developer G is wiped off at a portion protruding from the developing cover 58c. With such a configuration, the frictional force generated between the shielding sheet 70 and the sheet cleaning member 524 when the shielding sheet 70 is pulled out can be reduced, and the operability when the shielding sheet 70 is pulled out can be improved.
Further, similarly to the first modification example, the two sheet cleaning members 524 are arranged to face each other with the shielding sheet 70 interposed therebetween, so that the surface of the shielding sheet 70 and the sheet cleaning member 524 are in contact with each other without any gap in the entire axial direction. Can do. Thereby, the developer G adhering to the surface of the shielding sheet 70 can be cleaned evenly.

  Further, in the developing device 5 of Modification 2, the free end sides of the two sheet cleaning members 524 extend in the drawing direction. Further, the two sheet cleaning members 524 are fixed to the developing cover 58c by an adhesive surface 535 having a gradient, and are arranged so as to be pressed against each other by a restoring force for returning from a bent state to a flat plate shape. With these configurations, the two sheet cleaning members 524 fall over each other with respect to the gap generated after the shielding sheet 70 is pulled out, and the gap can be filled. Therefore, it is possible to prevent the developer G from leaking out from the cover opening 580 after the shielding sheet 70 is pulled out.

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)
A developer such as developer G composed of a magnetic carrier and toner is carried on the surface by a plurality of magnetic poles provided inside, and the cylindrical surface rotates to face a latent image carrier such as the photoreceptor 1. A developer carrying member such as a developing roller 50 for supplying toner to the latent image on the surface of the latent image carrying member in the developing region, and a developer such as a supply carrying path 53a and a collection carrying path 54a through which the developer is carried. A casing 58 that forms a developer conveyance path, and a supply conveyance member such as a supply screw 53 that conveys the developer in the conveyance path along the axial direction of the developer carrier and supplies the developer to the developer carrier. In a developing device such as the developing device 5 having a developing casing such as a developer casing and a developer regulating member such as a doctor blade 52 that regulates the amount of developer carried on the developer carrying member, the developer regulating member Opposite below the developer carrier Developer passing openings such as a supply opening 53b and a recovery opening 54b that are disposed and extend in the axial direction of the developer carrier and communicate the developer carrier with the inside of the developer transport path. A sheet member such as a shielding sheet 70 to be shielded is detachably provided, and in a state where the sheet member is attached, the developer passage opening portion of the sheet member such as the lower end portion 70a in the cross section orthogonal to the axial direction is shielded. On one end side, the sheet member passes through the gap between the developer regulating member and the developer carrying body, and the end thereof is located outside the gap between the developer regulating member and the developer carrying body. The opening of the cover opening 580 and the like provided in the upper portion of the developer conveyance path of the developing casing such as the developing cover 58c on the other end side with respect to the portion that shields the developer passing opening of the sheet member such as the portion 70b. Part Its end is located outside of the developing casing through which over preparative member.
According to this, as described in the above-described embodiment, it is possible to prevent the developer from coming into contact with the developer carrier in a state before use, while preventing an increase in the size of the developing device.
(Aspect B)
In Aspect A, the developer such as the developer G is delivered from the developer carrying member such as the developing roller 50 after passing through the developing region, and the developer is conveyed along the axial direction. The developer conveyance path includes a supply conveyance path such as a supply conveyance path 53a in which a supply conveyance member is arranged and a collection conveyance path 54a in which a collection conveyance member is arranged by a partition member such as a partition plate 57 that partitions the space. A developer supply opening, such as a supply opening 53b, which is partitioned by a recovery conveyance path, etc., and communicates between the developer carrier and the inside of the supply conveyance path, and a developer carrier. And a developer collection opening such as a collection opening 54b that communicates with the inside of the collection conveyance path, and a sheet member such as a shielding sheet 70 shields the developer supply opening and the developer collection opening. .
According to this, as described in the above embodiment, the toner image is applied in the axial direction of the toner image as compared with the developing device of the supply and recovery integrated type by applying to the developing device of the biaxial one-way circulation type. It is possible to prevent density deviation from occurring. In addition, space can be saved in the horizontal direction as compared with a three-axis one-way circulation developing device. Furthermore, since there is no need to secure a bonding margin, there is a plurality of developer passage openings such as a one-way circulation type developing device, and even if the shape of the opening to be shielded is complicated, the developing device is large. It is possible to prevent the developer from coming into contact with the developer carrying member before use.
(Aspect C)
In the aspect B, guide surfaces such as a sheet guide surface 58e for guiding a sheet member such as the shielding sheet 70 are formed at both ends in the axial direction of the developing casing such as the casing 58, and the developing roller 50 of the partition member such as the partition plate 57 is formed. The tip surfaces of the tip surface 57a and the like facing the developer carrier such as the end surface in the axial direction form a continuous surface with the guide surface, and the guide surface is a developer such as the doctor blade 52 from the position of the tip surface. In a shape along the surface of the developer carrier so that the distance between the surface of the developer carrier and the surface of the developer carrier is the same as the distance between the tip surface and the surface of the developer carrier over the position where the regulating member is disposed. is there.
According to this, as described with reference to FIGS. 10 and 11 in the above-described embodiment, the sheet member is prevented from being twisted or wrinkled by moving while being guided by the guide surface. can do. As a result, good shielding properties can be obtained in the space between the developer carrying member and the developer.
(Aspect D)
In any one of the aspects A to C, a plastic seal member such as a side seal 570 disposed at a gap between the surface of the developer carrier such as the developing roller 50 and the developing casing such as the casing 58 at both ends in the axial direction. The one end side of the sheet member such as the lower end portion 70a of the shielding sheet 70 is sandwiched between the plastic seal member and the surface of the developer carrier.
According to this, as described with reference to FIG. 8 in the above embodiment, it is possible to prevent the developer from wrapping around from the outside of the axial end portion of the sheet member and reaching the surface of the developer carrying member.
(Aspect E)
In any one of the aspects A to D, the sheet member is pulled from the other end side such as the upper end portion 70b in the cross section orthogonal to the upper axis direction of the sheet member such as the shielding sheet 70, and the outside of the developing casing such as the casing 58 The sheet member winding means such as a sheet winding device 525 for winding the sheet member is provided.
According to this, as described in the above-described embodiment, for this reason, it is possible to save the user's labor by omitting the manual operation by the user before using the developing device.
(Aspect F)
In any of the aspects A to E, the sheet member such as the shielding sheet 70 is a developing device such as the developing device 5 by pulling an end portion on the other end side such as the upper end portion 70b in a cross section orthogonal to the axial direction. Remove from.
According to this, as described in the above embodiment, the surface of the latent image carrier such as the photoreceptor 1 is prevented from being damaged, and good operability when the sheet member is pulled out can be obtained.
(Aspect G)
In any one of the aspects A to F, an opening sealing member such as a cover filter 523 that seals the developer from passing through the opening such as the cover opening 580 of the developing casing such as the casing 58 is provided. Gas can pass through the sealing member.
According to this, as described in the above embodiment, it is necessary to separately provide a member that shields the opening and a member that cleans the sheet member while suppressing the air pressure in the developing casing from being changed by the opening sealing member. The cost can be reduced.
(Aspect H)
In the aspect G, in a state where the sheet member such as the shielding sheet 70 is attached, the opening sealing member such as the cover filter 523 is disposed on the developer carrier such as the developing roller 50 with respect to the sheet member. .
According to this, as described with reference to FIG. 12 in the above embodiment, it is possible to prevent clogging from occurring in the opening sealing member before using the developing device.
(Aspect I)
In the aspect F or G, the sheet member such as the shielding sheet 70 is pulled to the other end side such as the upper end portion 70b in the portion where the opening portion such as the cover opening portion 580 of the developing casing such as the casing 58 is formed. A sheet cleaning member such as a sheet cleaning member 524 that cleans the sheet member in contact with the surface of the sheet member.
According to this, since the developer adhered to the sheet member can be wiped off by the sheet cleaning member as described in the above embodiment, the developer can be prevented from scattering.
(Aspect J)
In the aspect I, a plurality of sheet cleaning members such as the sheet cleaning member 524 are arranged so as to sandwich the sheet member such as the shielding sheet 70 and are plate-like members made of an elastic material, and are opposed to each other with the sheet member interposed therebetween. The two sheet cleaning members such as the cleaning member 524a and the second sheet cleaning member 524b are arranged in a folded state and pressed against each other with a restoring force from the folded state.
According to this, as described in the first modification, the gap can be filled even if the developing casing such as the developing cover 58c is deformed, and the state in which the sheet member is sandwiched between the two sheet cleaning members is maintained. Can do. For this reason, the contact state of the sheet cleaning member with respect to the sheet member can be maintained over the entire axial direction, and the developer attached to the sheet member can be cleaned evenly.
(Aspect K)
In aspect J, of the two sheet cleaning members such as the first sheet cleaning member 524a and the second sheet cleaning member 524b that are opposed to each other with the sheet member such as the shielding sheet 70 interposed therebetween, the development roller 50 or the like is developed with the sheet member interposed therebetween. The sheet cleaning member such as the first sheet cleaning member 524a on the material carrier side is more slidable than the sheet cleaning member such as the second sheet cleaning member 524b on the developer conveyance path side, and the sheet cleaning member on the developer conveyance path side is The cleaning property is better than the sheet cleaning member on the developer carrier side.
According to this, as described in the first modification, it is possible to more reliably prevent the developer from being scattered while improving the operability when the sheet member is pulled out.
(Aspect L)
In the aspect J or K, when the sheet member such as the shielding sheet 70 is pulled out from the opening such as the cover opening 580, the opening is closed by the sheet cleaning member such as the sheet cleaning member 524.
According to this, as described in the above embodiment, it is possible to prevent the developer from leaking from the opening after the sheet member is pulled out.
(Aspect M)
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, a writing unit for forming an electrostatic latent image on the latent image carrier, etc. In an image forming apparatus such as a copier 500 having a latent image forming means and a developing means for developing an electrostatic latent image into a toner image, any of the aspects A to L can be used as the developing means for the developing device 5 or the like. The developing device of this aspect is used.
According to this, as described in the above embodiment, the developer is prevented from adhering to the developer carrying member provided in the developing device before use, so that the developer is put on the developer carrying member before the start of use. It is possible to prevent the occurrence of image defects due to fixing.
(Aspect N)
In an image forming apparatus comprising a latent image carrier that carries a latent image and a developing unit that develops the latent image on the latent image carrier, at least the latent image carrier and the developing unit are shared as one unit. In the process cartridge such as the image forming unit 6 that is held by the holding body and is detachable from the main body of the image forming apparatus, the developing device according to any one of the aspects A to L is used as the developing unit of the developing device 5 or the like. .
According to this, as described in the above embodiment, the developer adheres to the developer carrier such as the developing roller 50 provided in the developing device before use when the process cartridge is stored or transported in the state of the process cartridge. Can be prevented.

DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Photoconductor cleaning apparatus 2a Cleaning blade 3 Original conveyance part 4 Original reading part 4a Charging roller 5 Developing apparatus 6 Image forming unit 7 Paper feed part 8 Intermediate transfer belt 9 Primary transfer bias roller 10 Intermediate transfer unit 11 Toner container 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 Paper discharge tray 40 Charging device 41 Lubricant coating device 50 Development roller 51 Development sleeve 52 Doctor blade 53 Supply screw 53a Supply conveyance path 53b Supply opening 54 Collection screw 54a Collection conveyance path 54b Collection opening 55 Magnet roller 57 Partition plate 57a Front end surface 58 Casing 58a Development lower case 58b Development upper case 58c Development cover 58d Pre-development case 58e Sheet guy Surface 59 Toner supply port 70 Shielding sheet 70a Lower end portion 70b Upper end portion 70c Sheet adhesive portion 71 Agent dropping port 72 Agent lifting port 100 Printer unit 500 Copying machine 523 Cover filter 524 Sheet cleaning member 524a First sheet cleaning member 524b First Two-sheet cleaning member 525 Sheet take-up device 525a Take-up shaft 535 Adhesive surface 552 Development area entrance seal 570 Side seal 570a Slit 580 Cover opening 581 Depressurization opening G Developer P Transfer paper P1 First magnetic pole P2 Second magnetic pole P3 Third magnetic pole P4 Fourth magnetic pole P5 Fifth magnetic pole

Japanese Patent No. 4341957 Japanese Patent No. 3104722 Japanese Patent Laid-Open No. 11-174810 Patent 3950735 JP 2008-026408 A JP 2011-174955 A JP 2000-122419 A

Claims (14)

A plurality of magnetic poles provided inside the developer comprising a magnetic carrier and the toner carried on the surface, the surface of the latent image bearing member in the developing area where the cylindrical surface facing the rotating latent image bearing member A developer carrier for supplying toner to the latent image above;
The developer in the developer conveyance path of the internal developer is conveyed, transported along the axial direction of the developer carrier, a supply transport member for supplying the developer to the developer carrying member,
A developing casing that forms the developer conveying path,
In the developing device having a developer regulating member for regulating the amount of developer carried on the developer carrying member,
The developer regulating member is disposed so as to face the lower portion of the developer carrying member,
The extending in the axial direction of the developer carrying member, provided with detachably sheet member for shielding the developer passage opening for communicating the interior of the developer transport path and the developer carrying member,
In the state of attaching the sheet member, one end side to the portion for shielding the developer passage openings of the sheet member in a cross section perpendicular to the axial direction, said the developer regulating member and the developer carrying member through the gap the sheet member is positioned outside the gap between the end of said one end of said sheet member and said developer regulating member and said developer carrying member,
Wherein the other end side with respect to the portion for shielding the developer passage openings of the sheet member, the opening of the upper side of the developing casing provided above the portion of the developer transport path through which the sheet member , a developing device, characterized in that the pulling end of said other end of said sheet member is fixed to the outside of the side away from the developer carrier with respect to the opening of the developing casing. The developing device according to claim 1.
Wherein after passing through the developing region passed a developer carrying member or al current image agent, a developer having a recovery conveying member for conveying along the axial direction,
The developer transport path, the partition member that partitions the space, the supply conveying member supply conveyance path were disposed, is partitioned into a recovery path disposed the recovery conveying member,
As the developer passage openings, the developer supply opening for communicating the interior of the developer carrying member and the supply conveyance path, and a developer for communicating the interior of the collection conveyance path and the developer carrying member Collecting opening, forming,
A developing device wherein the sheet member, characterized in that for shielding the developer supply opening and the developer collecting opening. The developing device according to claim 2.
Wherein forming a guide surface for guiding the sheet member at both ends of the axial direction of the developing casing,
The distal end surface facing the developer carrying member of the partition member, both ends of the axial direction to form a continuous surface and the guide surface,
The guide surface across said developer regulating member is disposed position from the position of the front end surface, the distance between the distance between the surface of the developer carrying member, wherein the distal end surface and the surface of the developer carrying member of the to match the developing device wherein the a shape along the surface of the developer carrying member. In the developing device according to any one of claims 1 to 3,
Comprising a plastic seal member disposed in a gap between the developer carrying member surface and the developer casing at both ends of the axial direction,
Wherein said one end of the sheet member, a developing apparatus characterized by being sandwiched between said plastic sealing member and the developer carrying member surface. In the developing device according to any one of claims 1 to 4,
Developing device from said the other end side in a cross section perpendicular to the axial direction of the sheet member pulling said sheet member, characterized in that it comprises a sheet member take-up means on the outside winding the sheet member of the developing casing. The developing device according to claim 1, wherein:
Said sheet member, a developing apparatus characterized by removing from the developing device by pulling on the end portion of the other end side in a cross section perpendicular to the axial direction. The developing device according to any one of claims 1 to 6,
An opening sealing member for sealing the opening portion of the developing casing as the developer does not pass,
The developing device characterized in that the opening sealing member allows gas to pass therethrough (suppresses fluctuations in atmospheric pressure). The developing device according to claim 7.
Wherein in the state in which the mounting seat member, a developing device wherein the opening sealing member is characterized by being arranged such that the side of the developer carrying member relative to the seat member. The developing device according to claim 5 or 6,
The portion forming the opening of the developing casing, when passing through the opening the sheet member is pulled to the other end, comprises a seat cleaning member for cleaning in contact with the surface of the sheet member A developing device. The developing device according to claim 9.
The sheet cleaning member, said a plurality of arranged so as to sandwich the sheet member is a plate-like member made of an elastic material,
2. The developing device according to claim 1, wherein the two sheet cleaning members facing each other with the sheet member interposed therebetween are arranged in a folded state and pressed against each other by a restoring force from the folded state. The developing device according to claim 10.
Wherein one of the two of the sheet cleaning member to opposite sides of the sheet member, the sheet cleaning member of the developing material carrier side across the sheet member may have sliding properties as compared with the sheet cleaning member of the developer conveying path ,
A developing device wherein the sheet cleaning member of the developer conveying path is characterized by good cleaning properties in comparison with the sheet cleaning member of the developing material carrier side. The developing device according to claim 10 or 11,
When withdrawing the sheet member from said opening, a developing device, characterized in that closing the opening portion by the sheet cleaning member. 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 12. A latent image carrier that carries a latent image, a common and said developing means and at least the image bearing member as one unit in an image forming apparatus and a developing means for developing the latent image on the latent image bearing member In the process cartridge that is held by the holding body and is detachable from the image forming apparatus main body,
13. A process cartridge using the developing device according to claim 1 as the developing means.

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