JP2011118077A - Developing device, process cartridge, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing device, a process cartridge, and an image forming apparatus that eliminate failure that a partition member separating a first conveyance path from a second conveyance path and opposed to a developer carrier bumps into the developer carrier during transportation, storage, etc. before starting the use of the developing device. <P>SOLUTION: A partition member 13d separating a first conveyance path by a first conveyance member 13b1 from a second conveyance path by a second conveyance member 13b2 is provided at the position opposed to a developer carrier 13a. Further, the partition member 13d is shrinkably formed in the direction away from the developer carrier 13a. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image forming apparatus using an electrophotographic system such as a copying machine, a printer, a facsimile, or a multifunction machine thereof, and a developing device and a process cartridge installed therein, and in particular, a developer in a longitudinal direction. The present invention relates to a developing device, a process cartridge, and an image forming apparatus in which at least two conveying members among a plurality of conveying members that are conveyed to form a circulation path are arranged to face a developer carrier.

  2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine or a printer, a developing device that contains a two-component developer composed of a toner and a carrier (including a case where an additive or the like is added), and the developer is long. At least two of the plurality of transport members that are transported in the direction to form a circulation path are installed in the vertical direction, and a developer carrying member that regulates the developer amount upstream of the developing region The technique of arrange | positioning below or below is known (for example, refer patent document 1, 2).

  In a developing device using a two-component developer, toner is appropriately replenished into the developing device from a toner replenishing port provided in a part of the developing device according to toner consumption in the developing device. The replenished toner is agitated and mixed together with the developer in the developing device by a conveying member (agitating and conveying member) such as a conveying screw. Part of the stirred and mixed developer is supplied to a developing roller (developer carrier). The developer carried on the developing roller is regulated to an appropriate amount by a doctor blade (developer regulating member) facing the developing roller, and then the toner in the two-component developer is separated from the photosensitive drum (image carrier). It adheres to the latent image on the photosensitive drum at the opposite position. A magnet is fixed inside the developing roller, and a plurality of magnetic poles are formed around the developing roller by the magnet.

In the developing device in Patent Document 1 or the like, a first conveying member (supply screw) and a second conveying member (collection screw) are installed in the vertical direction, and a developer circulation path is formed by these conveying members. ing. The first conveying member installed below supplies the developer to the developing roller at the position of the pumping magnetic pole while conveying the developer in the longitudinal direction. The second conveying member installed above conveys the developer separated from the developer roller at the position of the agent separating magnetic pole in the longitudinal direction (the direction opposite to the conveying direction by the first conveying member). The downstream side of the conveyance path (first conveyance path) by the first conveyance member and the upstream side of the conveyance path (second conveyance path) by the second conveyance member communicate with each other via the first relay unit. Then, the developer that has reached the downstream side of the first transport path stays at that position and is pushed up to reach the upstream side of the second transport path. Here, a toner supply port is provided on the upstream side of the second conveyance path, and new toner is appropriately supplied. In addition, the upstream side of the first transport path and the downstream side of the second transport path communicate with each other via the second relay unit. Then, the developer that has reached the downstream side of the second conveyance path falls by its own weight on the second relay unit and is moved to the upstream side of the first conveyance path.
Further, in the developing device in FIG. 20 of Patent Document 2, a doctor blade (developer regulating member) is disposed above the developing roller, and the first conveying member (supply screw) among the two conveying members facing the developing roller. ) Is disposed above the second conveying member (recovery screw).
In the developing device in which a plurality of conveying members are arranged in the vertical direction as described above, the developer does not flow between the first conveying path and the second conveying path at a position other than the relay unit. A partition member (separating plate) that partitions the first transport path and the second transport path is disposed so as to face the developing roller in the vicinity thereof.

  As described above, the developing device in which the plurality of conveying members are arranged in the vertical direction is a developing device as compared with the developing device in which the plurality of conveying members are arranged in the horizontal direction (for example, see FIG. 19 of Patent Document 2). Can be made compact in the horizontal direction. Therefore, a tandem type color image forming apparatus in which a plurality of developing devices are arranged in parallel in the horizontal direction is often used. In addition, a plurality of transport members are arranged in the vertical direction, and a developer supply path (first transport path) to the developer carrier and a developer recovery path (second transport path) that separates from the developer carrier. ) Is separated from the developing device in which a plurality of conveying members are arranged in parallel in the horizontal direction (for example, see FIG. 19 of Patent Document 2), and the developing device is used for the developing process. Since it is difficult for the developer to contain the toner after the development step, the density deviation of the toner image formed on the image carrier can be reduced.

  On the other hand, Patent Documents 3 and 4 disclose a developing device in which a developer is stored (preset) in advance in a developing device before the start of use, and is transported or stored before the use of the developing device is started. In order to prevent problems such as when the developer stored in the developing device scatters outside the device or when the developer stored in the developing device adheres to the developing roller and stains or damages the surface thereof. In addition, a technique is disclosed in which a developing roller and a storage portion (conveyance path) in which a developer is stored are separated by a seal member. The seal member is removed from the developing device when the user starts using the developing device.

In the developing devices described in Patent Documents 1 and 2 and the like described above, the partition member that partitions the first transport path and the second transport path facing the developer carrier is disposed so as to face the developer carrier in the vicinity. Therefore, during transportation or storage before the use of the developing device is started, the developing device receives an impact and the partition member hits the developer carrying member and damages the developer carrying member. There was a case.
In addition, such a developing device has a developer carrier and a first transport path in which the developer is accommodated in order to preliminarily accommodate (preset) the developer before the start of use as in Patent Documents 3 and 4. Even if it is attempted to install a seal member that isolates the second transport path, the partition member in the vicinity of the developer carrying member becomes in the way, making it difficult to install.

  The present invention has been made to solve the above-described problems. The first conveying path and the first conveying path that face the developer carrying member during transportation or storage before the use of the developing device is started. It is an object of the present invention to provide a developing device, a process cartridge, and an image forming apparatus in which a problem that a partition member that separates two conveyance paths does not collide with a developer carrier is generated.

  According to a first aspect of the present invention, there is provided a developing device for storing a developer having a carrier and a toner and developing a latent image formed on an image carrier, the image carrier. A plurality of conveying members that are opposed to the body and that carry a developer, and a plurality of conveying members that convey the developer contained in the apparatus in the longitudinal direction to form a circulation path. The member faces the developer carrying member and is arranged above or below the first carrying member for supplying the developer to the developer carrying member while conveying the developer in the longitudinal direction. And a second conveying member that conveys the developer separated from the developer carrying member in the longitudinal direction, at a position facing the developer carrying member. First transport by the first transport member Further comprising a partition member that partitions the second transport path by the a path second conveying member, wherein the partition member are those wherein is contractible formed in a direction away from the developer carrying member.

  According to a second aspect of the present invention, there is provided the developing device according to the first aspect, wherein the partition member is pulled out from a position separated from the developer carrier when the use of the device is started. After that, it abuts against the abutting portion and is positioned at a position facing the developer carrier.

  According to a third aspect of the present invention, there is provided the developing device according to the second aspect, wherein the partition member is directed from a position away from the developer carrying member to a position facing the developer carrying member. An urging member that urges and a regulating member that stops the partition member at a position spaced from the developer carrier so as to resist the urging force of the urging member, and the use of the apparatus is started. Sometimes, the stationary of the partition member by the restriction member is released.

  According to a fourth aspect of the present invention, in the developing device according to the first or second aspect, the partition member faces the developer carrying member from a position spaced from the developer carrying member. A gripping unit for moving to a position to be operated from the outside of the device, and a fixing member for determining the position of the gripping unit is provided outside the device, and when the use of the device is started, the gripping unit In addition, the partition member is pulled out from the position away from the developer carrier by manual operation of the fixing member, and is positioned at a position facing the developer carrier.

  A developing device according to a fifth aspect of the present invention is the developing device according to any one of the first to fourth aspects, wherein the partition member is removed from the developer carrier until the use of the device is started. A seal member is provided for isolating the first transport path and the second transport path from the developer carrying member in a contracted state at a separated position, and is provided in the first transport path and the second transport path. A developer is accommodated.

  According to a sixth aspect of the present invention, in the developing device according to the fifth aspect, the seal member can be peeled off into a case of the device and a front end portion of the partition member in a contracted state. It is formed so that it can be adhered or welded and removed from the outside of the apparatus.

  According to a seventh aspect of the present invention, there is provided the developing device according to the fifth or sixth aspect, wherein the seal member stops the partition member at a position separated from the developer carrier. It is.

  The process cartridge according to an eighth aspect of the present invention is a process cartridge that is detachably installed on the main body of the image forming apparatus, and is according to any one of the first to seventh aspects. The developing device and the image carrier are integrated.

  An image forming apparatus according to a ninth aspect of the present invention includes the developing device according to any one of the first to seventh aspects and the image carrier.

  In the present application, the “process cartridge” refers to a charging unit that charges the image carrier, a developing unit (developing device) that develops a latent image formed on the image carrier, and a cleaning on the image carrier. At least one of the cleaning units and the image carrier are defined as a unit that is integrated and detachably installed on the image forming apparatus main body.

  In the present invention, since the partition member that partitions the first transport path and the second transport path facing the developer carrying member is formed so as to be able to contract in a direction away from the developer carrying member, the use of the developing device can be performed. It is possible to provide a developing device, a process cartridge, and an image forming apparatus in which a problem that the partition member collides with the developer carrying member does not occur during transportation or storage before the start.

1 is an overall configuration diagram illustrating an image forming apparatus according to Embodiment 1 of the present invention. It is a block diagram which shows an image creation part. (A) The schematic sectional view which looked at the upper part of the developing device in the longitudinal direction, (B) The schematic sectional view which looked at the lower part of the developing device in the longitudinal direction. It is the schematic sectional drawing which looked at the circulation path of the developing device in the longitudinal direction. It is sectional drawing which shows a developing device. It is sectional drawing which shows the developing device before the start of use. It is an enlarged view which shows the state by which the partition member was contracted. It is a figure which shows the state in which the partition member is contacting the contact part. It is a figure which shows the principal part of the developing device in Embodiment 2 of this invention. It is a figure which shows the state by which the partition member was contracted.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected to the part which is the same or it corresponds, The duplication description is simplified or abbreviate | omitted suitably.

Embodiment 1 FIG.
The first embodiment of the present invention will be described in detail with reference to FIGS.
First, the configuration and operation of the entire image forming apparatus will be described with reference to FIG.
In FIG. 1, 1 is a main body of a tandem type color copier as an image forming apparatus, 3 is a document conveying unit that conveys a document to a document reading unit, 4 is a document reading unit that reads image information of a document, and 5 is an output image. , 7 is a paper feed unit that accommodates a recording medium P such as transfer paper, 9 is a registration roller that adjusts the conveyance timing of the recording medium P, and 11Y, 11M, 11C, and 11BK are each color (yellow). , Magenta, cyan, and black), a photosensitive drum as an image carrier on which a toner image is formed, and a developing device 13 that develops electrostatic latent images formed on the photosensitive drums 11Y, 11M, 11C, and 11BK. , 14 is a transfer bias roller (primary transfer bias roller) for transferring the toner images formed on the photosensitive drums 11Y, 11M, 11C, and 11BK on the recording medium P in an overlapping manner. It is.
Reference numeral 17 denotes an intermediate transfer belt onto which a plurality of color toner images are transferred, 18 denotes a secondary transfer bias roller for transferring the color toner image on the intermediate transfer belt 17 onto the recording medium P, and 20 denotes a recording medium. A fixing device 28 for fixing an unfixed image on P, and a toner container for each color for supplying toner (toner particles) of each color (yellow, cyan, magenta, black) to the developing device 13.

Hereinafter, an operation during normal color image formation in the image forming apparatus will be described. Note that FIG. 2 can also be referred to for the image forming process performed on the photosensitive drums 11Y, 11M, 11C, and 11BK.
First, the document is transported from the document table by the transport rollers of the document transport unit 3 and placed on the contact glass of the document reading unit 4. 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, a laser beam L (see FIG. 2) based on the image information of each color is emitted from the writing unit toward the corresponding photosensitive drums 11Y, 11M, 11C, and 11BK.

On the other hand, the four photosensitive drums 11Y, 11M, 11C, and 11BK are rotated clockwise in FIG. First, the surfaces of the photoconductor drums 11Y, 11M, 11C, and 11BK are uniformly charged at a portion facing the charging unit 12 (see FIG. 2) (charging process). Thus, a charged potential is formed on the photosensitive drums 11Y, 11M, 11C, and 11BK. Thereafter, the charged surfaces of the photosensitive drums 11Y, 11M, 11C, and 11BK reach the irradiation positions of the respective laser beams.
In the writing unit, laser beams corresponding to the image signals are emitted from the four light sources corresponding to the respective colors. Each laser beam passes through a separate optical path for each of the yellow, magenta, cyan, and black color components (this is an exposure process).

  Laser light corresponding to the yellow component is irradiated on the surface of the first photosensitive drum 11Y from the left side of the drawing. At this time, the yellow component laser light is scanned in the rotation axis direction (main scanning direction) of the photosensitive drum 11Y by a polygon mirror that rotates at high speed. Thus, an electrostatic latent image corresponding to the yellow component is formed on the photosensitive drum 11Y charged by the charging unit 12.

  Similarly, the laser beam corresponding to the magenta component is irradiated onto the surface of the second photosensitive drum 11M from the left side of the paper, and an electrostatic latent image corresponding to the magenta component is formed. The cyan component laser light is applied to the surface of the third photosensitive drum 11C from the left side of the paper, and an electrostatic latent image of the cyan component is formed. The black component laser beam is applied to the surface of the fourth photosensitive drum 11BK from the left side of the paper, and an electrostatic latent image of the black component is formed.

Thereafter, the surfaces of the photosensitive drums 11Y, 11M, 11C, and 11BK on which the electrostatic latent images of the respective colors are formed reach positions facing the developing device 13, respectively. Then, the respective color toners are supplied from the developing devices 13 onto the photosensitive drums 11Y, 11M, 11C, and 11BK, and the latent images on the photosensitive drums 11Y, 11M, 11C, and 11BK are developed (development process). .)
Thereafter, the surfaces of the photoconductive drums 11Y, 11M, 11C, and 11BK after the development process reach the facing portions of the intermediate transfer belt 17, respectively. Here, a transfer bias roller 14 is installed at each facing portion so as to contact the inner peripheral surface of the intermediate transfer belt 17. Then, the toner images of the respective colors formed on the photosensitive drums 11Y, 11M, 11C, and 11BK are sequentially superimposed and transferred onto the intermediate transfer belt 17 at the position of the transfer bias roller 14 (in the primary transfer process). is there.).

Then, the surfaces of the photosensitive drums 11Y, 11M, 11C, and 11BK after the transfer process reach positions facing the cleaning unit 15, respectively. Then, the untransferred toner remaining on the photosensitive drums 11Y, 11M, 11C, and 11BK is collected by the cleaning unit 15 (this is a cleaning process).
Thereafter, the surfaces of the photoconductive drums 11Y, 11M, 11C, and 11BK pass through a neutralization unit (not shown), and a series of image forming processes on the photoconductive drums 11Y, 11M, 11C, and 11BK is completed.

On the other hand, the intermediate transfer belt 17 on which the toners of the respective colors on the photosensitive drums 11Y, 11M, 11C, and 11BK are transferred (carrying) are run counterclockwise in the drawing, and the secondary transfer bias roller 18 Reach the opposite position. Then, a color toner image carried on the intermediate transfer belt 17 is transferred onto the recording medium P at a position facing the secondary transfer bias roller 18 (secondary transfer step).
Thereafter, the surface of the intermediate transfer belt 17 reaches the position of an intermediate transfer belt cleaning unit (not shown). Then, the untransferred toner attached on the intermediate transfer belt 17 is collected by the intermediate transfer belt cleaning unit, and a series of transfer processes in the intermediate transfer belt 17 is completed.

Here, the recording medium P transported between the intermediate transfer belt 17 and the secondary transfer bias roller 18 (secondary transfer nip) is transported from the paper supply unit 7 via the registration roller 9 and the like. It is a thing.
Specifically, the recording medium P fed by the paper feeding roller 8 from the paper feeding unit 7 that stores the recording medium P is guided to the registration roller 9 after passing through the conveyance guide. The recording medium P that has reached the registration roller 9 is conveyed toward the secondary transfer nip at the same timing.

Then, the recording medium P on which the full color image is transferred is guided to the fixing device 20 thereafter. In the fixing device 20, the color image is fixed on the recording medium P at the nip between the fixing roller and the pressure roller.
Then, the recording medium P after the fixing step is discharged as an output image outside the apparatus main body 1 by a discharge roller and stacked on the discharge tray 5 to complete a series of image forming processes.

Next, the image forming unit in the image forming apparatus will be described in detail with reference to FIGS.
FIG. 2 is a configuration diagram illustrating the image forming unit. 3A is a schematic cross-sectional view (horizontal cross-sectional view) of the upper portion of the developing device 13 (the position of the second transport screw 13b2 as the second transport member) in the longitudinal direction. (B) is a schematic cross-sectional view of the lower part of the developing device 13 (the position of the first conveying screw 13b1 as the first conveying member) in the longitudinal direction. FIG. 4 is a schematic cross-sectional view (vertical cross-sectional view) of the circulation path of the developing device 13 as viewed in the longitudinal direction. FIG. 5 is a cross-sectional view (a cross-sectional view orthogonal to the rotation center axis of the developing roller 13a) showing the developing device, and the method of magnetic poles H1 to H5 formed on the developing roller 13a in the drawing. The magnetic force distribution of the linear component is also shown. Further, FIG. 6 is a cross-sectional view showing the developing device 12 before the start of use, and shows a state in which the partition member 13d is contracted (stored) at a position separated from the developing roller 13a. FIG. 7 is an enlarged cross-sectional view showing a state in which the partition member 13d is contracted. FIG. 8 is a top view illustrating a state in which the partition member 13d is in contact with the abutting portion 13m1, and is a diagram illustrating a state when the developing device 13 is being used.
Since each image forming unit has substantially the same structure, the image forming unit and the developing device are illustrated in FIGS. 2 to 8 without the alphabet (Y, C, M, BK).

As shown in FIG. 2, the image forming unit includes a photosensitive drum 11 as an image carrier, a charging unit 12, a developing device 13 (developing unit), a cleaning unit 15, and the like.
The photoconductor drum 11 as an image carrier is a negatively charged organic photoconductor having an outer diameter of about 30 mm, and is driven to rotate counterclockwise by a rotation drive mechanism (not shown).

The charging unit 12 is a charging roller having elasticity in which a foamed urethane layer having a medium resistance in which a urethane resin, carbon black as conductive particles, a sulfurizing agent, a foaming agent, and the like are formed in a roller shape on a core metal. The material of the middle resistance layer of the charging unit 12 is urethane, ethylene-propylene-diene polyethylene (EPDM), butadiene acrylonitrile rubber (NBR), silicone rubber, isoprene rubber, etc. It is also possible to use a rubber material in which a conductive material such as the above is dispersed or a foamed material of these materials.
The cleaning unit 15 is provided with a cleaning blade that is in sliding contact with the photosensitive drum 11, and mechanically removes and collects untransferred toner on the photosensitive drum 11.

  The developing device 13 is disposed such that a developing roller 13a as a developer carrying member is close to the photosensitive drum 11, and a developing region (developing) where the photosensitive drum 11 and the magnetic brush are in contact with each other. Nip) is formed. A developer G (two-component developer) composed of toner T and carrier C is accommodated in the developing device 13. In the present embodiment, 225 grams of developer G having a toner concentration of 7% by weight is accommodated in the developing device 13. The developing device 13 develops the electrostatic latent image formed on the photosensitive drum 11 (forms a toner image). The configuration and operation of the developing device 13 will be described in detail later.

Referring to FIG. 1, toner container 28 contains toner T to be supplied into developing device 13 therein. Specifically, toner conveyance (not shown) is performed based on information on the toner density (the ratio of toner in the developer G) detected by a magnetic sensor (not shown) installed in the developing device 13. The toner T is appropriately supplied from the toner supply port 13e from the toner container 28 into the developing device 13 through the tube.
The supply of the toner T is not limited to the toner density information, but may be performed based on the image density information detected from the reflectance of the toner image formed on the photosensitive belt or the intermediate transfer belt. Good. Further, the implementation of the supply of the toner T may be determined by combining these different pieces of information.

Hereinafter, the developing device 13 in the image forming apparatus will be described in detail.
2 to 6, the developing device 13 includes a developing roller 13a as a developer carrying member, conveying screws 13b1 and 13b2 (auger screws) as conveying members, a doctor blade 13c as a developer regulating member, and a partition. It is comprised by the member 13d.
A developing roller 13a as a developer carrying member is a developing roller having a small outer diameter of about 18 mm, and includes a sleeve 13a2 formed by forming a non-magnetic material such as aluminum, brass, stainless steel, or conductive resin into a cylindrical shape. It is configured to be rotated counterclockwise at about 150 to 600 rpm by a rotation driving mechanism (not shown). 3 and 5, a magnet 13a1 for forming a plurality of magnetic poles H1 to H5 is fixed on the peripheral surface of the sleeve 13a2 in the sleeve 13a2 of the developing roller 13a. The developer G carried on the developing roller 13a is conveyed as the developing roller 13a rotates in the direction of the arrow, and reaches the position of the doctor blade 13c. The developer G on the developing roller 13a is regulated to an appropriate amount at this position, and then conveyed to a position facing the photosensitive drum 11 (which is a developing region). The toner is attracted to the latent image formed on the photosensitive drum 11 by the electric field (developing electric field) formed in the developing area.

FIG. 5 shows a plurality of magnetic poles H1 to H5 formed around the developing roller 13a (sleeve 13a2) by the magnet 13a1. As shown in FIG. 5, the plurality of magnetic poles are a first magnetic pole H1 (main magnetic pole) formed at a position facing the photoconductive drum 11, and downstream of the first magnetic pole H1 and in the case 13m (developing case). A second magnetic pole H2 (conveying magnetic pole) formed at a position over the upper part, a third magnetic pole H3 (conveying magnetic pole) formed downstream of the second magnetic pole H2 and upward in the second conveying path, Position where the fourth magnetic pole H4 (opposing magnetic pole) formed on the downstream side of the three magnetic poles H3 and facing the partition member 13d, and the position facing the first conveying screw 13b1 beyond the position facing the doctor blade 13c And a fifth magnetic pole H5 (pumping magnetic pole) formed over the top.
First, the fifth magnetic pole H5 (pumping magnetic pole) acts on a carrier as a magnetic material, and the developer G accommodated in the first transport path is pumped onto the developing roller 13a. Part of the developer G carried on the developing roller 13a is scraped off at the position of the doctor blade 13c (developer regulating member) and returned to the first transport path. On the other hand, the developer G carried on the developing roller 13a through the doctor gap between the doctor blade 13c and the developing roller 13a at the position of the doctor blade 13c where the magnetic force by the fifth magnetic pole H5 acts is the first magnetic pole H1. It rises at the position of the (main magnetic pole) and becomes a magnetic brush in the developing region, and comes into sliding contact with the photosensitive drum 11. Thus, the toner T in the developer G carried on the developing roller 13 a adheres to the latent image on the photosensitive drum 11. Thereafter, the developer G that has passed through the position of the first magnetic pole H1 is conveyed to the position of the fourth magnetic pole H4 (opposing magnetic pole) by the second magnetic pole H2 and the third magnetic pole H3. The developer G after the development process carried on the developing roller 13a at the position of the counter magnetic pole H4 is held between the developing roller 13a and the partition member 13d by the magnetic pole of the counter magnetic pole H4. It is detached from the developing roller 13a so as to be pushed out by G. The detached developer G falls into the second transport path along the inclination of the upper surface of the partition member 13d and is transported downstream of the second transport path by the second transport screw 13b2.

  Referring to FIG. 5, in the first embodiment, the half-value central angle of the first magnetic pole H1 (the central position of the region where the peak magnetic force is halved is the center of the developing roller 13a and the photosensitive drum 11 in FIG. The angle formed in the counterclockwise direction with respect to the line connecting the center of the second magnetic pole H) is −5 °, the half-width central angle of the second magnetic pole H2 is 58 °, the half-width central angle of the third magnetic pole H3 is 120 ° The half-value central angle of the four magnetic poles H4 is set to 205 °, and the half-value central angle of the fifth magnetic pole H5 is set to 280 °. The first magnetic pole H1 has a peak magnetic force of 100 mT, the second magnetic pole H2 has a peak magnetic force of 85 mT, the third magnetic pole H3 has a peak magnetic force of 52 mT, the fourth magnetic pole H4 has a peak magnetic force of 70 mT, and the fifth magnetic pole H5 has a peak magnetic force. It is set to 78 mT.

Here, referring to FIG. 5, the five magnetic poles H1 to H5 described above have five poles magnetized on the magnet 13a1 of the developing roller 13a (in FIG. 5, “(N)” or “(S ) ”Is a magnetic pole formed by“) ”. Here, of the five magnetic poles H1 to H5, the counter magnetic pole H4 and the fifth magnetic pole H5 adjacent to the downstream side (the downstream side in the rotation direction of the developing roller 13a) have the same polarity (this embodiment). 1 is the S pole). Therefore, a repulsive magnetic field (a magnetic field acting in a direction away from the developing roller 13a) is formed between the opposing magnetic pole H4 and the fifth magnetic pole H5 adjacent to each other. The repulsive magnetic field acts on the developer G that attempts to pass through the gap between the partition member 13d and the developing roller 13a, and the developer G from above the developing roller 13a at the position of the fourth magnetic pole H4 (opposing magnetic pole). The withdrawal is promoted.
The configuration / operation of the partition member 13d will be described in more detail later.

Referring to FIG. 2 and the like, a doctor blade 13c as a developer regulating member (first developer regulating member) is a non-magnetic plate-like member (a part of which is magnetically disposed below the developing roller 13a). It can also be made of a material. The developing roller 13a rotates counterclockwise in FIG. 2, and the photosensitive drum 11 rotates clockwise in FIG.
With such a configuration, the photosensitive drum 11 is disposed below the intermediate transfer belt 17 for the purpose of shortening the conveyance path of the recording medium P and reducing the horizontal size of the image forming apparatus main body 1. Even so, since the rotation direction of the developing roller 13a can be the forward direction with respect to the photosensitive drum 11 in the developing gap, the doctor blade 13c is provided above the developing roller 13a and the photosensitive drum 11 is disposed. As compared with the case where the rotation direction of the developing roller 13a is opposite, the developing time in the developing gap can be sufficiently secured and the developing ability can be enhanced.

The two conveying screws 13b1 and 13b2 (conveying members) stir and mix the developer G accommodated in the developing device 13 while circulating in the longitudinal direction (the direction perpendicular to the paper surface of FIG. 2).
The first transport screw 13b1 as the first transport member is disposed at a position facing the developing roller 13a, and transports the developer G horizontally in the longitudinal direction (rotation axis direction) (see FIG. 3B). In addition, the developer G is supplied onto the developing roller 13a at the position of the pumping magnetic pole H5 (fifth magnetic pole) (the supply in the direction of the white arrow in FIG. 3B). .) The first transport screw 13b1 rotates counterclockwise in FIG.

The second conveying screw 13b2 as the second conveying member is disposed above the first conveying screw 13b1 and at a position facing the developing roller 13a. Then, the developer G released from the developing roller 13a (the developer G forcibly released from the developing roller 13a after the developing step, which is released in the direction of the white arrow in FIG. 3A). It is transported horizontally in the longitudinal direction (this is the transport in the right direction indicated by the broken line arrow in FIG. 3A). In the first embodiment, the rotation direction of the second conveying screw 13b2 is set to be opposite to the rotation direction of the developing roller 13a (the clockwise direction in FIG. 2).
Then, the second transport screw 13b2 has a second developer G circulated from the downstream side of the transport path by the first transport screw 13b1 via the first relay portion 13f to the upstream side of the transport path by the first transport member 13b1. It conveys via the relay part 13g (it is the conveyance shown by the dashed-dotted arrow of FIG. 3).
The two conveying screws 13b1 and 13b2 are arranged so that the rotation shaft is substantially horizontal, like the developing roller 13a and the photosensitive drum 11. Moreover, as for the two conveyance screws 13b1 and 13b2, both have a screw part (screw pitch: about 40 mm, number of threads: one or two) with a shaft part with a shaft diameter of about 6 to 10 mm and an outer diameter of about 20 mm. It is wound in a spiral. Moreover, the rotation speed of the two conveyance screws 13b1 and 13b2 is set to about 600 to 900 rpm.

The conveyance path (first conveyance path) by the first conveyance screw 13b1 and the conveyance path (second conveyance path) by the second conveyance screw 13b2 are isolated from each other by a wall portion.
3 and 4, the downstream side of the transport path (second transport path) by the second transport screw 13b2 and the upstream side of the transport path (first transport path) by the first transport screw 13b1 are 2 It communicates via the relay part 13g. The developer G that has reached the downstream side of the second conveyance path by the second conveyance screw 13b2 falls by its own weight at the second relay portion 13g and reaches the upstream side of the first conveyance path.
3 and 4, the downstream side of the conveyance path by the first conveyance screw 13b1 and the upstream side of the conveyance path by the second conveyance screw 13b2 communicate with each other via the first relay unit 13f. Yes. Then, the developer G that has not been supplied onto the developing roller 13a in the first conveyance path by the first conveyance screw 13b1 stays in the vicinity of the first relay portion 13f and rises up, and then passes through the first relay portion 13f. It is transported (supplied) to the upstream side of the second transport path by the two transport screws 13b2.
In addition, in order to improve the transportability of the developer (transfer of the developer against the direction of gravity from the first transport path to the second transport path) in the first relay portion 13f, the first transport screw 13b1 A paddle-shaped portion or a screw portion in which the winding direction of the screw is formed in the reverse direction can be provided at a downstream position (a position corresponding to the first relay portion 13f).

  With such a configuration, a circulation path for circulating the developer G in the longitudinal direction in the developing device 13 is formed by the two conveying screws 13b1 and 13b2. That is, when the developing device 13 is operated, the developer G accommodated in the device flows in the direction of the broken line arrow in FIGS. 3 and 4. Thus, the developer G supply path (the first transport path by the first transport screw 13a1) to the developing roller 13a and the developer G recovery path (second transport screw) separated from the developing roller 13a. 13a2), the density deviation of the toner image formed on the photosensitive drum 11 can be reduced.

Although illustration is omitted, a magnetic sensor for detecting the toner concentration of the developer circulating in the apparatus is installed in the conveyance path by the second conveyance screw 13b2. Then, based on the toner density information detected by the magnetic sensor, the toner container 28 is directed into the developing device 13 through the toner supply port 13e (located in the vicinity of the first relay portion 13f). New toner T is supplied.
3 and 4, the toner replenishing port 13e is located above the upstream side of the transport path by the second transport screw 13b2 and away from the developing area (the range in the longitudinal direction of the developing roller 13a). It is arranged outside.). By installing the toner replenishing port 13e in the vicinity of the first relay portion 13f in this way, the developer detached from the developing roller 13a falls from above the replenishment toner having a small specific gravity in the second transport path, and the second transport path. The replenishment toner can be sufficiently dispersed and mixed with respect to the developer over a relatively long time toward the downstream side.
In the first embodiment, the toner replenishment port 13e is disposed in the conveyance path by the second conveyance screw 13a2, but the position of the toner replenishment port 13e is not limited to this, and for example, the first conveyance path It can also be arranged above the upstream side.

  Referring to FIG. 4, in the first transport path, in order to supply the developer to the developing roller 13a while transporting the developer in the longitudinal direction, the upstream side except for the vicinity of the first relay portion 13f. The developer surface of the developer G becomes lower as it goes downstream. On the other hand, in the second transport path, the developer surface of the developer G is directed from the upstream side toward the downstream side in order to collect the developer separated from the developing roller 13a while transporting the developer in the longitudinal direction. Is getting higher.

Hereinafter, the developer G used in Embodiment 1 will be briefly described.
The toner T (the toner in the developer G and the toner in the toner container 28) used in the first embodiment is a polymerized toner, and a styrene-acrylonitrile-acrylic acid ester copolymer is used as a binder resin. Styrenic resins (monopolymer or copolymer containing styrene or styrene-substituted product), polyester resins, epoxy resins, or composites thereof can be used. In addition, as a production method (polymerization method) of these polymerized toners, bulk polymerization, solution polymerization, emulsion polymerization, suspension polymerization, and the like can be used.
Further, as the external additive of the toner T, it is preferable to use inorganic fine particles (for example, those having 1.0% by weight of silica and 0.5% by weight of titanium oxide). Furthermore, oxidized rice wax, low molecular weight polypropylene wax, carnauba wax and the like can be used as a release agent. Moreover, a charge control agent can be contained as required.
The toner T used in the first embodiment is a small-diameter toner having a volume average particle diameter of 5.8 μm, and the toner T having a particle diameter of 5 μm or less is formed to be 60 to 80% by number.
In the first embodiment, polymerized toner is used, but pulverized toner can also be used.

The carrier C in the developer G used in the first embodiment is a small-diameter carrier formed so that the weight average particle diameter is 20 to 60 μm. In the first embodiment, the carrier C formed so that the weight average particle diameter is 35 μm is used.
Specifically, the carrier C is formed by coating the ferrite particles serving as the core material with a methyl methacrylate resin (MMA) having a film thickness of 0.5 μm so as to have the above-described particle size. As the carrier C, a coating carrier having magnetite as a core material can also be used.
By using the carrier C having such a small particle diameter, the solid uniformity of the output image and the halftone image quality can be improved. Further, since the carrier C having such a small particle size can increase the carrier coverage of the toner, it has a good compatibility with a small particle size toner suitable for high image quality.

Hereinafter, a characteristic configuration and operation of the developing device 13 according to the first embodiment will be described.
Referring to FIG. 5, the developing device 13 according to the first embodiment is provided with a partition member 13d (separating plate) that partitions the first transport path and the second transport path at a position facing the developing roller 13a. ing. In other words, the developer G released from the developing roller 13a is reduced from being carried on the developing roller 13a again between the first conveying path and the second conveying path at a position facing the developing roller 13a. A partition member 13d is provided.
Specifically, the partition member 13d functions as a wall portion that separates the first conveyance path and the second conveyance path, and is formed to protrude toward the developing roller 13a. In addition, the partition member 13d is formed integrally with a case 13m (a case member indicated by hatching in FIG. 2). The partition member 13d is formed so that the gap CG between the facing surface facing the developing roller 13a and the developing roller 13a is 2 mm or less (preferably 0.1 to 0.5 mm). In the first embodiment, the gap CG is set to 0.3 mm.
Since the partition member 13d is formed of a non-magnetic material, the carrier, which is a magnetic material, is magnetically attracted to the partition member 13d to obstruct the flow of the developer in the second transport path. Problems such as promoting the movement of the developer to the transport path are reduced.

Referring to FIG. 6, the developing device 13 according to the first embodiment is formed so that the partition member 13d can be contracted in a direction away from the developing roller 13a (in the direction of the broken arrow). That is, the partition member 13d has a position shown by a broken line in FIG. 6 (a position close to the developing roller 13a and a position shown in FIG. 5) and a position shown by a solid line in FIG. It is configured to be able to expand and contract between.
Specifically, with reference to FIG. 7, the partition member 13d has an extendable portion 13d1 covering the tip of the main body portion 13d2. Further, a hole is formed at the tip of the main body 13d2 of the partition member 13d, and a compression spring 13d3 as an urging member is embedded in the hole. The compression spring 13d3 functions as a biasing member that biases the partition member 13d (expandable portion 13d1) from a position spaced from the developing roller 13a toward a position facing (close to) the developing roller 13a.
Since the developer flows on the partition member 13d, the sealability (sealing performance) of both the members 13d1 and 13d2 is ensured within a range that does not significantly affect the sliding of the expansion / contraction portion 13d1 with respect to the main body portion 13d2. Yes.

  In this way, the partition member 13d is formed so as to be contractible in the direction away from the developing roller 13a, so that the partition member 13d can be used for the developing roller 13a during transportation or storage before the use of the developing device 13 is started. The problem of hitting and damaging the developing roller 13a is less likely to occur. That is, even if the partition member 13d hits the developing roller 13a due to vibration during transportation of the developing device 13, the partition member 13d contracts in a direction away from the developing roller 13a due to an external force acting on the partition member 13d at that time. Therefore, damage to the developing roller 13a can be reduced.

  Here, in the first embodiment, in order to further secure the above-described effect, the developing device 13 before use is resisted against the spring force of the compression spring 13d3 (the biasing force of the biasing member). As described above, the seal member 13k is installed as a regulating member that stops the expansion / contraction part 13d1 (partition member 13d) at a position separated from the developing roller 13a.

  Specifically, the seal member 13k is attached to the developing device 13 assembled at the manufacturing factory in a state where the developer G is stored (preset) in the first transport path and the second transport path (FIG. 6). Is the state.) The seal member 13k is for isolating the first conveyance path and the second conveyance path in which the developer G is stored from the developing roller 13a, and is used during transportation before the use of the developing device 13 is started. During storage or the like, the developer G accommodated in the developing device 13 is scattered outside the device, or the developer G accommodated in the developing device 13 adheres to the developing roller 13a and stains or damages the surface thereof. Prevent malfunctions. The seal member 13k is removed (peeled) from the developing device 13 when the use of the developing device 13 is started by the user, so that the developing device 13 can be used in the image forming apparatus main body 1. Become.

Further, as shown in FIG. 6, the seal member 13k is in a state in which the partition member 13d (expandable portion 13d1) is contracted to a position away from the developing roller 13a (the state shown in FIG. 7), and the developer G is in the state. The accommodated first transport path and second transport path are installed so as to be separated from the developing roller 13a. That is, the partition member 13d (expandable portion 13d1) is held (stationary) at a position separated from the developing roller 13a by the seal member 13k.
Specifically, the seal member 13k is a thin sheet-like member made of a resin material such as vinyl, and is a position surrounded by a broken line in FIG. 6 (the case 13m and the tip of the partition member 13d in a contracted state). .) Is releasably adhered (or welded). In this state, the partition member 13d (expandable portion 13d1) is held at a position separated from the developing roller 13a by the tension of the seal member 13k adhered to the case 13m in a balanced manner. During transportation before storage is started, during storage, etc., the problem that the partition member 13d hits the developing roller 13a and damages the developing roller 13a is reliably prevented.

The seal member 13k is removed from the developing device 13 when the use of the developing device 13 is started under the user.
Specifically, first, the knob portion 13k1 of the seal member 13k protruding outside the developing device 13 is picked, and the portion of the seal member 13k attached to the upper portion of the case 13m is peeled off. Thereafter, the seal member 13k is pulled out in the diagonally left direction (in the direction of the arrow) in FIG. 6 to complete the removal operation of the seal member 13k from the developing device 13. Then, when the sealing member 13k as the regulating member is removed from the developing device 13, the stationary state of the partition member 13d (expandable portion 13d1) is released. As a result, the partition member 13d (expandable portion 13d1) is stretched to a position close to and opposed to the developing roller 13a by the biasing force of the compression spring 13d3 (biasing member), and is normally held (positioned) at that position. The function as the partition member 13d in the developing process is exhibited.

Here, in the first embodiment, as shown in FIG. 8, the partition member 13d (expandable portion 13d1) is separated from the developing roller 13a when the seal member 13k is removed when the use of the developing device 13 is started. After being pulled out from the separated position, the abutting portion 13d4 abuts against the abutting portion 13m1 of the case 13m and is positioned at a position facing the developing roller 13a.
With such a configuration, the gap between the developing roller 13a and the partitioning member 13d during use can be easily optimized even when the partitioning member 13d is deformable to be stretchable.

  As described above, in the first embodiment, the partition member 13d is configured to be extendable and retractable, so that the developing roller 13a and the developer G are preliminarily stored (preset) before the start of use. The seal member 13k that separates the accommodated first conveyance path and the second conveyance path can be installed in a state where the partition member 13d is contracted to a position away from the developing roller 13a. That is, the problem that the partition member 13d adjacent to the developing roller 13a becomes an obstacle and the installation of the seal member 13k becomes difficult is solved. Further, there is no need to provide a developer preset container separately from the developing device 13, and as shown in FIG. 6, the seal member 13k can be installed compactly in a plane within a minimum range.

  In the first embodiment, in order to remove the sealing member 13k, the hole formed in the upper portion of the case 13m is provided with a sealing material 13n that is in close contact with the cut portion even if the sealing member 13k is removed. Has been. Thereby, the malfunction which a developer leaks outside from the hole part formed in the upper part of case 13m is suppressed irrespective of the presence or absence of removal of the sealing member 13k.

Here, with reference to FIG. 5, in the present embodiment, the second transport screw 13b2 (second transport member) is viewed in a cross section (FIG. 5) perpendicular to the rotation center axis of the developing roller 13a. In addition, the position of the rotation center axis of the second transport screw 13b2 is disposed below the virtual horizontal line passing through the upper end of the developing roller 13a and above the virtual horizontal line passing through the lower end of the developing roller 13a. . That is, the position of the rotation center axis of the second transport screw 13b2 (or the virtual horizontal line S2 passing therethrough) is disposed in the range indicated by the double arrow M1.
With such a configuration, the developer G after the development process carried on the developing roller 13a is pushed out by the developer G staying between the developing roller 13a and the partition member 13d at the position of the opposing magnetic pole H4. In addition to the pressure, centrifugal force due to the rotation of the developing roller 13a, force received from the repulsive magnetic field formed by the fourth magnetic pole H4 and the fifth magnetic pole H5, and the like act. As a result, the developer G after the developing process carried on the developing roller 13a is efficiently separated from the developing roller 13a at the position upstream of the partition member 13d without causing a failure to separate from the developing roller 13a. The separated developer G is smoothly collected in the second transport path. Accordingly, it is difficult for the developer G to be detached after the developing process carried on the developing roller 13a, and the developer G after the developing process released from the developing roller 13a in the second transport path is developed immediately thereafter. It becomes difficult for the roller 13a to be re-supported, and the problem that the image density unevenness (density deviation) or the image density is lowered on the output image is surely reduced.
In the first embodiment, the position of the rotation center axis of the second transport screw 13b2 (or the virtual horizontal line S2 passing therethrough) is the position of the rotation center axis of the developing roller 13a (or the virtual horizontal line S1 passing therethrough). ), The above-described effects are more reliably exhibited.

  Further, with reference to FIG. 5, in the first embodiment, when viewed in a cross section orthogonal to the rotation center axis of the developing roller 13a, the tip of the partition member 13d has the rotation center axis of the second transport screw 13b2. It is formed so as to be above the virtual horizontal line S2 that passes therethrough. As a result, it is possible to reduce a problem that the developer G collected in the second transport path flows over the partition member 13d and flows into the first transport path.

Further, in the first embodiment, the inclination angle (the angle formed with the horizontal plane) of the inclined surface (an inclined surface formed on the second transport path side) of the partition member 13d is the developer G. It is formed to be larger than the angle of repose. Here, the angle of repose of the developer is an angle formed by the ridge line of the developer crest that rises in a conical shape by dropping the developer on the horizontal plane and the horizontal plane. -S "(manufactured by Hosokawa Micron Corporation) can be used.
With such a configuration, the developer G separated from the developing roller 13a at the position of the fourth magnetic pole H4 is smoothly guided to the second transport path without staying along the inclined surface of the partition member 13d. It is possible to reduce a problem that the developer after the separation is re-supported by the developing roller 13a.
In order to reliably prevent the developer having a small diameter with poor fluidity from staying on the inclined surface, it is preferable that the inclined angle of the inclined surface of the partition member 13d be 40 degrees or more. In the first embodiment, the inclination angle of the inclined surface is set to about 45 degrees.

Further, referring to FIG. 5, in the first embodiment, the position of the rotation center axis of the first conveyance screw 13b1 is the second conveyance screw 13b2 when viewed in a cross section orthogonal to the rotation center axis of the developing roller 13a. The first conveying screw 13b1 is located between the virtual vertical line passing through the rotation center axis of the developing roller 13a and the virtual vertical line passing through the rotation center axis of the developing roller 13a (between the range M2 in FIG. 5). It is arranged.
Accordingly, the first transport screw 13b1 can be brought close to the pumping magnetic pole H5 of the developing roller 13a, and the supply capability of the developer G to the developing roller 13a by the first transport screw 13b1 can be enhanced.

  As described above, in the first embodiment, the partition member 13d that partitions the first conveyance path and the second conveyance path facing the developing roller 13a (developer carrying member) in a direction away from the developing roller 13a. Since it is formed so as to be shrinkable, it is possible to prevent a problem that the partition member 13d hits the developing roller 13a during transportation or storage before the use of the developing device 13 is started.

Embodiment 2. FIG.
A second embodiment of the present invention will be described in detail with reference to FIGS.
FIG. 9 is a top view illustrating a main part of the developing device 13 according to the second embodiment, and corresponds to FIG. 8 according to the first embodiment. FIG. 10 is a top view showing a state in which the partition member 13d is contracted.
The developing device 13 in the second embodiment is different from that in the first embodiment in which the partition member 13d is automatically extended from the outside of the developing device 13 in that the partition member 13d is manually operated from the outside.

  Similarly to the first embodiment, the developing device 13 according to the second embodiment also has a developing roller 13a (developer carrying member), two conveying screws 13b1, 13b2 (conveying member), a doctor blade 13c (developer). A restricting member), a partition member 13d, and the like. Also in the second embodiment, the partition member 13d is formed so as to be contractible in a direction away from the developing roller 13a.

  Here, the partition member 13d in the second embodiment is provided with a gripping portion 13d5 for moving from a position away from the developing roller 13a to a position facing the developing roller 13a from the outside of the developing device 13. Yes. In addition, a fixing plate 13p and a fixing screw 13w are installed outside the developing device 13 as fixing members for determining the position of the grip portion 13d5 (partition member 13d). When the use of the developing device 13 is started and the removal of the seal member 13k is completed, the partition member 13d is pulled out from the position separated from the developing roller 13a by manual operation of the gripping portion 13d5 and the fixing members 13p and 13w. Thus, positioning to a position facing the developing roller 13a is performed.

Specifically, as shown in FIG. 10, before the use of the developing device 13 is started (during packing), the extendable portion 13d1 of the partition member 13d is held at a position away from the developing roller 13a.
A boss-shaped gripping part 13d5 protruding from both ends of the expansion / contraction part 13d1 (partition member 13d) is provided with a long hole 13m2 formed on the side of the case 13m and a hole formed in the fixing plate 13p. Exposed outside the device. Then, in FIG. 10, the fixing screw 13 w is a screw hole formed in the fixing member 13 p at a position where the gripping portion 13 d 5 comes into contact with the lower end of the long hole 13 m 2 (the position where the expansion and contraction portion 13 d 1 contracts). And is screwed into a first female thread portion (not shown) formed in the case 13m. As a result, the partition member 13d (expandable portion 13d1) is held at a position sufficiently separated from the developing roller 13a.
In the second embodiment as well, in the developing device 13 before the start of use, the first transport path and the second transport path in a state where the partition member 13d is contracted (the state shown in FIG. 10). Developer G is preset. As in the first embodiment, the seal member 13k is pasted so as to isolate the first transport path and the second transport path from the developing roller 13a in a state where the partition member 13d is contracted. ing.

When the use of the developing device 13 is started, the seal member 13k is removed as in the first embodiment. And in this Embodiment 2, the extending | stretching operation | movement of the partition member 13d is performed manually.
Specifically, for the developing device 13 in the state of FIG. 10, after the screwing of the fixing screw 13w from the case 13m is once released, the gripping portion 13d5 is operated from the outside of the device to operate the partition member 13d (expandable) The portion 13d1) is pulled out to a position close to the developing roller 13a (the position in FIG. 9). Specifically, the fixing screw 13w is inserted through the screw hole formed in the fixing member 13p at the position where the gripping portion 13d5 abuts on the upper end of the long hole 13m2 (the position where the expansion / contraction portion 13d1 extends). And a second female screw portion (not shown, formed at a position different from the first female screw portion described above) formed in the case 13m. Thereby, the partition member 13d (expandable portion 13d1) is held at a position sufficiently close to the developing roller 13a.
In addition, in order to prevent the developer from leaking from the long hole 13m2 formed in the case 13m, the sealing performance (adhesion) between the fixing plate 13p and the case 13m is sufficiently ensured.

  As described above, also in the second embodiment, similarly to the first embodiment, the partition member 13d that partitions the first transport path and the second transport path facing the developing roller 13a (developer carrier) is provided. Further, since it is formed so as to be able to contract in a direction away from the developing roller 13a, there is a problem that the partition member 13d hits the developing roller 13a during transportation or storage before the use of the developing device 13 is started. It can be prevented from occurring.

  In each of the above embodiments, the toner T is supplied from the toner container 28 toward the developing device 13. However, the developer G (toner T and carrier C) is directed toward the developing device 13 from the toner container (developer container). Can also be supplied. In that case, a means for appropriately discharging excess developer from the developing device 13 is provided. Even in such a case, it is possible to obtain the same effects as those of the above embodiments.

  In each of the above embodiments, the present invention is applied to an image forming apparatus in which the developing device 13 is configured as a unit that is detachably attached to the main body of the image forming apparatus. However, the application of the present invention is not limited to this, and the present invention can naturally be applied to an image forming apparatus in which a part or all of the image forming unit is formed as a process cartridge. In that case, the workability of maintenance of the image forming unit is improved.

Further, in each of the above embodiments, the present invention is applied to the developing device 13 in which two conveying screws as conveying members are installed. However, three or more conveying screws are installed, and at least two conveying screws are included. The present invention can also be applied to a developing device installed so as to face the developing roller 13a.
In the embodiment, the developing device in which the second conveying screw 13b2 functioning as a recovery screw is installed above the first screw 13b1 functioning as a supply screw, and the doctor blade 13c is installed below the developing roller 13a. The present invention was applied to 13. On the other hand, the second conveying screw 13b2 that functions as a recovery screw is installed below the first screw 13b1 that functions as a supply screw, and the doctor blade 13c is installed above the developing roller 13a. Of course, the present invention can be applied.
In each of the above embodiments, the number of magnetic poles H1 to H5 formed around the developing roller 13a is five. However, the number of magnetic poles formed around the developing roller 13a is four or less, or six or more. It can also be.
And also in those cases, the same effect as each said embodiment can be acquired by comprising the partition member 13d so that expansion-contraction is possible.

  It should be noted that the present invention is not limited to the above-described embodiments, and within the scope of the technical idea of the present invention, the embodiments can be modified as appropriate in addition to those suggested in the embodiments. Is clear. In addition, the number, position, shape, and the like of the constituent members are not limited to the above embodiments, and can be set to a number, position, shape, and the like that are suitable for carrying out the present invention.

1 image forming apparatus body (apparatus body),
11, 11Y, 11C, 11M, 11BK Photosensitive drum (image carrier),
13 Developing device (developing part),
13a Development roller (developer carrier),
13b1 first conveying screw (first conveying member),
13b2 second conveying screw (second conveying member),
13c Doctor blade (developer regulating member),
13d partition member,
13d1 telescopic part, 13d2 body part,
13d3 compression spring (biasing member),
13d4 contact part, 13d5 grip part,
13k sealing member (regulating member),
13m case,
13m1 abutment part,
13p fixing plate (fixing member),
13w fixing screw (fixing member),
G developer (two-component developer), T toner, C carrier.

Japanese Patent Laid-Open No. 11-174810 JP 2008-26408 A JP 2002-268353 A Japanese Patent No. 4003411

Claims (9)

A developing device that contains a developer having a carrier and toner and that develops a latent image formed on an image carrier,
A developer carrying body facing the image carrying body and carrying a developer;
A plurality of transport members that transport the developer contained in the apparatus in the longitudinal direction to form a circulation path;
With
The plurality of conveying members are:
A first conveying member facing the developer carrying member and supplying the developer to the developer carrying member while conveying the developer in the longitudinal direction;
A second conveying member disposed above or below the first conveying member so as to face the developer carrying member and convey the developer detached from the developer carrying member in the longitudinal direction;
Comprising
A partition member that partitions the first transport path by the first transport member and the second transport path by the second transport member at a position facing the developer carrier;
The developing device according to claim 1, wherein the partition member is formed to be contractible in a direction away from the developer carrying member.   When the use of the apparatus is started, the partition member is pulled out from a position away from the developer carrier and then abuts against the abutting portion to be positioned at a position facing the developer carrier. The developing device according to claim 1. A biasing member that biases the partition member from a position spaced from the developer carrier to a position facing the developer carrier;
A regulating member that stops the partition member at a position spaced from the developer carrier so as to resist the biasing force of the biasing member;
With
The developing device according to claim 2, wherein when the use of the apparatus is started, the stationary of the partition member by the restriction member is released. The partition member includes a gripping portion for moving from a position away from the developer carrier to a position facing the developer carrier from the outside of the apparatus.
A fixing member for determining the position of the grip portion is provided outside the apparatus,
When the use of the apparatus is started, the partition member is pulled out from a position away from the developer carrier by manual operation of the gripping part and the fixing member, and positioned to a position facing the developer carrier. The developing device according to claim 1, wherein: the developing device according to claim 1.   A seal for isolating the first transport path and the second transport path from the developer carrier in a state where the partition member is contracted to a position spaced from the developer carrier until the use of the apparatus is started. The developing device according to claim 1, wherein a member is installed and a developer is accommodated in the first transport path and the second transport path.   The seal member is detachably bonded or welded to a case of the apparatus and a distal end portion of the partition member in a contracted state, and is formed so as to be removable from the outside of the apparatus. Item 6. The developing device according to Item 5.   The developing device according to claim 5, wherein the seal member stops the partition member at a position separated from the developer carrier. A process cartridge that is detachably installed on the main body of the image forming apparatus,
8. A process cartridge, wherein the developing device according to claim 1 and the image carrier are integrated.   An image forming apparatus comprising the developing device according to claim 1 and the image carrier.

Images