JP2013117563A - Developing device, process cartridge, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing device, a process cartridge, and an image forming apparatus that prevent toner from scattering out from an opening of the developing device, formed near a developing area, and securely prevent the trouble that the toner is accumulate on the counter face of a casing member opposite a developer carrier and the accumulated toner falls.SOLUTION: A first sealing member 13v is installed such that the leading end thereof is in contact with the upstream side place of the developing area in the running direction of the image carrier 11. A second sealing member 13w is installed such that the root thereof is held on the counter face of the casing member 13p, the leading end is suspended by itself in the direction in which the leading end approaches the upstream place of the developing area in the running direction of the developer carrier 13a, and it contacts developer held by the developer carrier 13a. In the second sealing member 13w, the surface layer 13w2 opposite the developer carrier 13a is made of a conductive material.

Description

  The present invention relates to an image forming apparatus using an electrophotographic system such as a copying machine, a printer, a facsimile machine, or a multifunction machine thereof, and a developing device and a process cartridge installed therein.

  2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine or a printer, a technique for installing an inlet seal in a developing device that contains a two-component developer composed of toner and a carrier (including cases where an additive or the like is added). Is known (for example, see Patent Document 1).

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 such as a conveying screw. Part of the stirred and mixed developer is supplied to a developing roller (developer carrier). After the developer carried on the developing roller is regulated to an appropriate amount by a doctor blade (developer regulating member), the toner in the two-component developer is opposed to the photosensitive drum (image carrier) (development area). ) To adhere to the latent image on the photosensitive drum.
In such a developing device, in order to prevent toner from scattering from the opening of the developing device formed in the vicinity of the developing region, the upstream side in the rotational direction of the photosensitive drum with respect to the developing region. A flexible inlet seal (seal member) is attached to the casing of the developing device so as to contact the position of the developing device.

  On the other hand, Patent Document 1 discloses a toner that collects or accumulates toner on an opposing surface of the developing casing that faces the developing roller, in addition to a seal member (developer scattering preventing sheet) that prevents toner scattering from the opening of the developing casing. Has disclosed a technique of installing a seal member (developer accumulation prevention sheet) for preventing a problem that the ink drops.

In the developing device described in Patent Document 1 and the like described above, the toner scatters to the outside from the opening of the developing device formed in the vicinity of the developing region, and the toner accumulates on the facing surface of the casing member facing the developer carrier. It can be expected to some extent that the effect of preventing the trouble that the accumulated toner falls is compatible.
However, there is a possibility that the toner adheres electrostatically to the opposite surface of the developer accumulation preventing sheet, and the latter effect cannot be sufficiently achieved.

  The present invention has been made to solve the above-described problems, and prevents a problem that toner is scattered outside from the opening of the developing device formed in the vicinity of the developing region, so that it faces the developer carrying member. It is an object of the present invention to provide a developing device, a process cartridge, and an image forming apparatus that can reliably prevent a problem that toner accumulates on the opposing surface of a casing member or the accumulated toner falls.

  A developing device according to a first aspect of the present invention is a developing device for developing a latent image formed on the surface of an image carrier that travels in a predetermined direction while containing a developer having a carrier and toner. And forming a developing region facing the image bearing member, a developer bearing member carrying the developer and traveling in a predetermined direction, and forming a gap facing the developer bearing member, A developer regulating member that regulates the amount of developer carried on the developer carrying member; and at least the developer with respect to the developing region from the downstream side in the running direction of the developer carrying member with respect to the position of the gap. A casing member formed so as to face the developer carrying member up to a position upstream in the traveling direction of the carrier, and a root portion is held by the casing member, and the image with respect to the developing region. Burden The base portion is disposed on the opposite surface of the casing member facing the developer carrying member and the first seal member having flexibility, and the tip portion is installed at a position upstream of the body in the traveling direction. The developer held and held on the developer carrying body at the position upstream of the developing area in the running direction of the developer carrying body with its leading end hanging down in the direction approaching the developer carrying body. A second seal member having flexibility, and the second seal member is formed of a conductive material on a surface layer facing the developer carrier. It is a thing.

  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. It is defined as a unit in which at least one of the cleaning units and the image carrier are integrated and installed detachably with respect to the image forming apparatus main body.

  In the present invention, the first seal member and the second seal member are installed at optimum positions, respectively, and the surface layer of the second seal member facing the developer carrier is formed of a conductive material. As a result, the problem of toner scattering to the outside from the opening of the developing device formed in the vicinity of the developing region is suppressed, and toner accumulates on the facing surface of the casing member facing the developer carrying member, or the accumulated toner falls. Thus, it is possible to provide a developing device, a process cartridge, and an image forming apparatus that can reliably prevent such problems.

1 is an overall configuration diagram illustrating an image forming apparatus according to an embodiment of the present invention. It is a block diagram which shows an image creation part. It is a perspective view which shows a developing device. (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 sectional drawing which shows the vicinity of the 3rd relay part of a developing device. It is sectional drawing which shows the vicinity of the discharge port of a developing device. It is sectional drawing which shows the vicinity of the supply port of a developing device. It is sectional drawing which shows the vicinity of opening of the conveyance path | route for discharge | emission. It is an enlarged view showing the vicinity of a development area. It is an enlarged view which shows the vicinity of the image development area | region in the image development apparatus of another form.

Embodiment.
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.

First, the configuration and operation of the entire image forming apparatus will be described with reference to FIG.
In FIG. 1, reference numeral 1 denotes an apparatus main body of a tandem color copier as an image forming apparatus, 2 a writing unit that emits laser light based on input image information, and 3 an original conveying unit that conveys an original D to an original reading unit 4. 4 is a document reading unit that reads image information of the document D, 7 is a paper feeding 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, and 11C. , 11BK are photosensitive drums on which toner images of respective colors (yellow, magenta, cyan, and black) are formed, 12 is a charging unit that charges the photosensitive drums 11Y, 11M, 11C, and 11BK, and 13 is each photosensitive drum. A developing device for developing electrostatic latent images formed on 11Y, 11M, 11C, and 11BK, and a toner image formed on each of the photosensitive drums 11Y, 11M, 11C, and 11BK Transfer bias roller for transferring superimposed on the recording medium P (1 transfer bias roller), 15 denotes the photosensitive drums 11Y, 11M, 11C, cleaning unit for collecting the untransferred toner on 11BK, a.

Reference numeral 16 denotes an intermediate transfer belt cleaning unit that cleans the intermediate transfer belt 17, 17 an intermediate transfer belt on which toner images of a plurality of colors are transferred and superimposed, and 18 a color toner image on the intermediate transfer belt 17 on the recording medium P. A secondary transfer bias roller 20 for transferring the toner image onto the recording medium P indicates a fixing device for fixing an unfixed image on the recording medium P.
Although not shown in the drawing, a carrier (magnetic carrier) and toner (toner particles) of each color (yellow, cyan, magenta, black) are developed above the photosensitive drums 11Y, 11C, 11M, and 11BK. Each color agent cartridge is installed as a supply means for supplying to 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 D is transported from the document table in the direction of the arrow in the drawing by the transport rollers of the document transport unit 3 and placed on the contact glass 5 of the document reading unit 4. Then, the document reading unit 4 optically reads the image information of the document D placed on the contact glass 5.

  Specifically, the document reading unit 4 scans the image of the document D on the contact glass 5 while irradiating light emitted from an illumination lamp. Then, the light reflected by the document D is imaged on the color sensor via the mirror group and the lens. The color image information of the document D is read for each RGB (red, green, blue) color separation light by the color sensor, and then converted into an electrical image signal. Further, color conversion processing, color correction processing, spatial frequency correction processing, and the like are performed by the image processing unit based on the RGB color separation image signals to obtain yellow, magenta, cyan, and black color image information.

  Then, the image information of each color of yellow, magenta, cyan, and black is transmitted to the writing unit 2. The writing unit 2 emits laser light L (see FIG. 2) based on the image information of each color 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 (this is a 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 2, laser light corresponding to the image signal is emitted from the four light sources corresponding to each color. 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 photoconductive 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 in the clockwise direction in FIG. 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 the intermediate transfer belt cleaning unit 16. Then, the untransferred toner adhered on the intermediate transfer belt 17 is collected by the intermediate transfer belt cleaning unit 16, 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 by the transport belt. In the fixing device 20, the color image (toner) is fixed on the recording medium P at the nip between the fixing belt 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 paper discharge roller, and a series of image forming processes is completed.

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 and the agent cartridge 28. FIG. 3 is a perspective view showing the developing device. 4A is a schematic cross-sectional view of the upper portion of the developing device 13 (the positions of the first conveying screw 13b1 and the discharging conveying screw 13k) in the longitudinal direction, and FIG. It is the schematic sectional drawing which looked at the lower part (the position of the 2nd conveyance screw 13b2 and the 3rd conveyance screw 13b3) in the longitudinal direction. 5 is a cross-sectional view showing the vicinity of the third relay portion 13h of the developing device 13, FIG. 6 is a cross-sectional view showing the vicinity of the discharge port 13d of the developing device 13, and FIG. 7 is a replenishing port 13e of the developing device 13. FIG. 8 is a cross-sectional view showing the vicinity of the opening 13r of the discharge transport path. Further, FIG. 9 is an enlarged view showing the vicinity of the development region.
Since each image forming unit has almost the same structure, and each agent cartridge has almost the same structure, the image forming unit and the agent cartridge are denoted by alphabets (Y, C, M, BK) is shown in the figure.

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.
A photosensitive drum 11 as an image carrier is a negatively charged organic photosensitive member, and is rotated counterclockwise by a drive motor (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 brush (or 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 arranged such that a developing roller 13a as a developer carrying member is close to the photosensitive drum 11, and a developing region where the photosensitive drum 11 and the magnetic brush are in contact with each other is formed. Is done. A developer G (two-component developer) composed of toner T and carrier C 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).
Specifically, the developer G on the developing roller 13a is regulated to an appropriate amount at the position facing the doctor blade 13c (the position of the doctor gap), and then the position facing the photosensitive drum 11 (the developing area). )). 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. A predetermined developing bias (voltage) is applied to the developing roller 12 a from the power supply unit 41, and a developing electric field is formed between the developing roller 12 a and the photosensitive drum 11. In addition, an opening is formed in the vicinity of the developing area in the developing device 13 so that the developing roller 13 a faces the photosensitive drum 11.
The configuration and operation of the developing device 13 will be described in detail later.

Here, the developing device 13 in the present embodiment is of a premix developing system, and a new carrier C (developer G) is appropriately supplied from the agent cartridge 28 into the developing device 13 and deteriorated. The developer G thus discharged is discharged toward a agent storage container (not shown) through a discharge path 70 (see FIG. 4) installed outside the developing device 13.
Referring to FIG. 2, the agent cartridge 28 accommodates developer G (toner T and carrier C) to be supplied into the developing device 13 therein. The agent cartridge 28 functions as a toner cartridge that supplies new toner T to the developing device 13, and also functions as a supply unit that supplies new carrier C to the developing device 13. Specifically, based on information on toner density (which is the ratio of toner in the developer G) detected by a magnetic sensor (not shown) installed in the developing device 13, the shutter driving unit performs shutter. The mechanism 80 is opened and closed to appropriately supply the developer G from the agent cartridge 28 serving as a supply unit into the developing device 13. Here, in the present embodiment, the mixing ratio of the carrier C in the toner T in the developer G of the agent cartridge 28 is set to about 10 wt%.
The supply of the developer G is not limited to the toner density information, but is 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. Also good. Further, the implementation of the supply of the developer G may be determined by combining these different pieces of information.

  The supply pipe 29 as a supply means is for reliably guiding the developer G (toner T and carrier C) supplied from the agent cartridge 28 into the developing device 13. That is, the developer G discharged from the agent cartridge 28 is supplied into the developing device 13 through the supply pipe 29 from the supply port 13e (developer supply port).

Hereinafter, the developing device 13 in the image forming apparatus will be described in detail.
2 to 9, the developing device 13 includes a developing roller 13a as a developer carrying member, conveying screws 13b1 to 13b3 (auger screws) as conveying members, a doctor blade 13c as a developer regulating member, discharge. A discharge conveying screw 13k as a conveying member, an inlet case 13p as a casing member, a first inlet seal 13v as a first seal member, a second inlet seal 13w as a second seal member, and the like.
The developing roller 13a (developer carrying member) has an outer diameter of 25 mm, and a sleeve formed of a nonmagnetic material such as aluminum, brass, stainless steel, or conductive resin in a cylindrical shape is a drive motor (not shown). )) To be rotated clockwise. Referring to FIG. 4, a magnet 13 a 1 that forms a magnetic field is fixed in the sleeve 13 a 2 of the developing roller 13 a so as to cause the developer G to rise on the peripheral surface of the sleeve. The carrier C in the developer G rises in a chain shape on the sleeve 13a2 so as to follow the normal line of magnetic force emitted from the magnet 13a1. The charged toner T is attached to the carrier C that is spiked in a chain shape to form a magnetic brush. The magnetic brush is transferred in the same direction (clockwise) as the sleeve 13a2 by the rotation of the sleeve 13a2.

Referring to FIG. 2, the doctor blade 13c (developer regulating member) is installed on the upstream side of the developing area so as to face the developing roller 13a with a predetermined gap (doctor gap) therebetween. The developer G carried on the developing roller 13a is regulated to an appropriate amount.
In the present embodiment, a cooling unit 13n is installed in the vicinity of the doctor blade 13c. The cooling unit 13n is a hollow structure in which a plurality of fins are provided, and air is sent into the inside from a fan (not shown). As a result, the temperature rise of the doctor blade 13c made of a metal material is reduced (air-cooled), and toner sticking to the doctor blade 13c and the developing roller 13a is suppressed.

The three conveying screws 13b1 to 13b3 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 (rotational axis direction) (see FIG. 4A). In addition, the developer G is supplied onto the developing roller 13a (in the direction of the white arrow in FIG. 4A).

  The second conveyance screw 13b2 as the second conveyance member is disposed below the first conveyance screw 13b1 and at a position facing the developing roller 13a. Then, the developer G separated from the developing roller 13a (the developer G forcibly separated from the developing roller 13a by the agent separation pole after the developing step, and separated in the direction of the white arrow in FIG. 4B). Is transported horizontally in the longitudinal direction (the transport is in the right direction indicated by the broken arrow in FIG. 4B).

The 3rd conveyance screw 13b3 as a 3rd conveyance member is a position adjacent to the 2nd conveyance screw 13b2, and is arrange | positioned diagonally below the 1st conveyance member 13b1. The third transport screw 13b3 transports the developer G transported by the second transport screw 13b2 to the upstream side of the transport path by the first transport member 13b1, and from the downstream side of the transport path by the first transport screw 13b1. The developer G circulated through the first relay portion 13f is transported to the upstream side of the transport path by the first transport member 13b1 (the transport in the left direction indicated by the broken-line arrow in FIG. 4B).
The three conveying screws 13b1 to 13b3 are arranged so that the rotation shaft is substantially horizontal, like the developing roller 13a and the photosensitive drum 11. In addition, the three conveying screws 13b1 to 13b3 are obtained by spirally winding a screw part around a shaft part, and the outer diameter of the screw part is set to 22 mm. Each of the three transport screws 13b1 to 13b3 is connected to a drive motor via a gear train (not shown) and is driven to rotate in a predetermined direction by the drive motor.

In addition, the conveyance path by the 1st conveyance screw 13b1, the conveyance path by the 2nd conveyance screw 13b2, the conveyance path by the 3rd conveyance screw 13b3, the conveyance path for discharge by the discharge conveyance screw 13k (discharge conveyance member), Are isolated by a partition (wall).
Referring to FIG. 4B, the downstream side of the conveyance path by the second conveyance screw 13b2 and the upstream side of the conveyance path by the third conveyance screw 13b3 communicate with each other via the second relay unit 13g. Also, referring to FIGS. 4A and 4B, the downstream side of the transport path by the first transport screw 13b1 and the upstream side of the transport path by the third transport screw 13b3 are the first relay portion 13f. It communicates through. 4A, FIG. 4B, and FIG. 5, the downstream side of the transport path by the third transport screw 13b3 and the upstream side of the transport path by the first transport screw 13b1 are the third. It communicates via the relay part 13h. Referring to FIG. 5, the developer G staying and rising in the vicinity of the third relay portion 13 h in the transport route by the third transport screw 13 b 3 is transported by the first transport screw 13 b 1 via the third relay portion 13 h. It is conveyed (supplied) to the upstream side.

  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 three transport screws 13b1 to 13b3. That is, when the developing device 13 is operated, the developer G accommodated in the device flows in the direction of the broken arrow in FIG. In this way, the developer G supply path to the developing roller 13a (the transport path by the first transport screw 13a1) and the developer G recovery path to be separated from the developing roller 13a (by the second transport screw 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 third conveyance screw 13b3. Then, based on the toner density information detected by the magnetic sensor, a developer G having a predetermined toner density is supplied from the agent cartridge 28 serving as a supply unit into the developing device 13 through the supply port 13e.
3, 4B, and 7, the replenishment port 13e is located upstream of the upstream side of the transport path by the third transport screw 13b3 and away from the development area (the development roller 13a). Outside the range in the longitudinal direction.).

Here, referring to FIG. 2, FIG. 4A, and FIG. 6, a part of the developer G accommodated in the developing device 13 is placed outside the transport path on the partition wall of the transport path by the first transport screw 13b1. A discharge port 13d for discharging is provided.
In detail, the discharge port 13d (discharge means) is supplied with the developer G into the developing device 13 by the supply means 28, 29, 80, and the developer amount in the device increases to be conveyed to that position. When the developer surface (upper surface) exceeds a predetermined height, the excess developer G is discharged toward the discharge conveyance path (the discharge conveyance screw 13k is installed). is there. The developer discharged from the discharge port 13d is transported in the longitudinal direction (the left direction in FIG. 4A) by the discharge transport screw 13k and falls by its own weight from the opening 13r (also see FIG. 8). Then, after being discharged out of the apparatus (discharge path 70), it is recovered into the agent storage container (not shown) via the discharge path 70. That is, the excess developer G exceeds the height below the discharge port 13 d, is discharged from the discharge port 13 d, and stores the agent via the discharge conveyance path (discharge conveyance screw 13 k) and the discharge path 70. It is transported toward the container. As described above, the carrier deteriorated by being contaminated with the base resin or the external additive of the toner T is automatically discharged to the outside of the developing device, so that deterioration of the image quality can be suppressed over time. The discharge path 70 is connected to all the discharge conveyance paths of the developing devices 13 for each color (four), and the developer discharged from each developing device 13 is collected together in the agent storage container.

  In addition, the conveyance path by the 1st conveyance screw 13b1 in this Embodiment is the vicinity of the discharge port 13d, and the ceiling part 13m adjacent to the 1st conveyance screw 13b1 is installed above the 1st conveyance screw 13b1. . Specifically, referring to FIG. 2, FIG. 4 (A), and FIG. 6, the ceiling portion 13m is opposed to narrow the gap above the first conveying screw 13b1 (screw portion) in the vicinity of the discharge port 13d. The surface is formed in an arc shape following the outer diameter shape of the screw portion of the first conveying screw 13b1. As a result, in the vicinity of the discharge port 13d, the developer surface (upper surface) of the developer is increased by the gap narrowed by the ceiling portion 13m. Accordingly, excess developer is discharged from the discharge port 13d located at a position higher than the rotation center of the first transport screw 13b1. Note that the gap amount and the longitudinal range between the ceiling portion 13m and the first conveying screw 13b1 can be determined based on the results of experiments so that the amount of developer discharged from the discharge port 13d is optimized.

  In addition, the discharge conveying screw 13k in the present embodiment has a shaft portion (outer diameter: 2 mm) extending in the longitudinal direction and a screw portion (outer diameter: spirally wound around the shaft portion). 8 mm). Further, similarly to the three transport screws 13b1 to 13b3, the discharge transport screw 13k is disposed so that the rotation shaft is substantially horizontal. And in this Embodiment, the conveyance screw 13k for discharge is also rotationally driven with a drive motor with the three conveyance screws 13b1-13b3.

Here, referring to FIG. 9 and the like, the inlet case 13p as a casing member is connected to the developing roller 13a from the downstream side in the rotation direction of the developing roller 13a (downstream in the running direction) with respect to the position of the doctor gap. Is formed so as to face the developing roller 13a up to a position upstream in the rotational direction (upstream in the traveling direction). That is, the inlet case 13p is installed so as to cover the upper side of the developing roller 13a at a position from the position of the doctor blade 13c to the vicinity of the position facing the photosensitive drum 11 along the rotation direction of the developing roller 13a. . The inlet case 13p functions as a part of the casing (housing) of the developing device 13, and is formed of a resin material or a metal material. The inlet case 13p is screwed to the main part of the casing of the developing device 13 together with the doctor blade 13c.
9 and the like, the inlet case 13p includes a first inlet seal 13v as a flexible first seal member and a second inlet seal 13w as a flexible second seal member. And are attached.

The first inlet seal 13v (first seal member) is made of Mylar having a thickness of about 0.01 to 0.3 mm, and the root portion (the portion that contacts the inlet case 13p) is the tip of the inlet case 13p. Is held (adhered) to the step portion of the photosensitive drum 11 with a double-sided tape, and the tip thereof contacts the position on the upstream side in the rotation direction (upstream side in the running direction) of the photosensitive drum 11 with respect to the developing region (photosensitive drum 11 This is a forward contact that follows the rotation of the
In this way, by installing the first inlet seal 13v (first seal member), the opening of the developing device 13 formed in the vicinity of the developing region (a part of the developing roller 13a is exposed). The problem of toner scattering to the outside is suppressed.

  The root of the second inlet seal 13w (second seal member) (the range indicated by the alternate long and short dash line in FIG. 9) is the facing surface of the inlet case 13p (the surface facing the developing roller 13a). Is held (adhered) via a double-sided tape, and its leading end hangs down by its own weight in a direction approaching the developing roller 13a at a position upstream of the developing roller 13a in the rotational direction (upstream in the running direction) with respect to the developing region. It is installed as follows. That is, the second inlet seal 13w is not attached to the entire area of the opposing surface of the inlet case 13p, but is attached only to a part of the opposing surface of the inlet case 13p, and the tip part hangs down under its own weight. It is installed so that there is a gap from the facing surface of the entrance case 13p from the top to the front end. With such a configuration, at least the front end portion of the second inlet seal 13w always comes into contact with the developer G carried on the developing roller 13a (the developer G that has risen). Therefore, even if toner adheres to the surface of the second inlet seal 13w, the toner is scraped off by the developer G carried on the developing roller 13a, so that toner accumulates on the surface of the second inlet seal 13w, It is possible to suppress a problem that the accumulated toner falls as a lump on the developing roller 13a and causes an abnormal image.

Further, in the second inlet seal 13w (second seal member) in the present embodiment, the surface layer 13w2 on the side facing the developing roller 13a is formed of a conductive material. Specifically, the second inlet seal 13w is formed by depositing aluminum on a base layer 13w1 made of Mylar having a thickness of about 0.01 to 0.3 mm to form a thin surface layer 13w2 (aluminum layer). is there.
In this manner, the opposing surface (surface layer 13w2) of the second inlet seal 13w is formed of a conductive material, so that the toner T in the developer G carried on the developing roller 13a (the toner in a frictionally charged state). .) Is less likely to electrostatically adhere to the second inlet seal 13w (surface layer 13w2). Therefore, the function of the above-described second inlet seal 13w (a function of suppressing the problem that toner accumulates on the surface of the second inlet seal 13w or the accumulated toner falls as a lump onto the developing roller 13a. .) Will be demonstrated more reliably.
In particular, in the present embodiment, since the surface layer 13w2 of the second inlet seal 13w is formed of aluminum having good thermal conductivity, the developer G carried on the developing roller 13a is exposed to the surface of the second inlet seal 13w. Even if heat is generated by sliding contact with the layer 13w2, the heat is diffused and radiated by the surface layer 13w2. Therefore, the problem that the developer G (toner T) carried on the developing roller 13a is solidified by heat and becomes a lump is reduced.

Further, in the present embodiment, the distal end portion of the second inlet seal 13w is formed so as to be positioned closer to the developing region than the distal end portion of the first inlet seal 13v.
Thereby, the function of the 2nd inlet seal 13w mentioned above and the function of the 1st inlet seal 13v are effectively exhibited mutually, without being inhibited by the other party's inlet seal.

In the present embodiment, the surface layer 13w2 of the second inlet seal 13w is configured to be in an electrically floating state.
On the other hand, as shown in FIG. 10, a voltage having the same potential as the developing bias applied to the developing roller 13a may be applied to the surface layer 13w2 of the second inlet seal 13w. Specifically, a voltage (having the same potential as the developing bias) is applied from the power supply unit 41 (developing bias supply unit) to the surface layer 13w2 of the second inlet seal 13w through a conduction path (not shown). To do.
With such a configuration, the toner T in the developer G carried on the developing roller 13a (the toner in a frictionally charged state) is less likely to adhere to the second inlet seal 13w (surface layer 13w2). . Therefore, the function of the above-described second inlet seal 13w (a function of suppressing the problem that toner accumulates on the surface of the second inlet seal 13w or the accumulated toner falls as a lump onto the developing roller 13a. .) Will be demonstrated more reliably.

  As described above, in the present embodiment, the first inlet seal 13v (first seal member) and the second inlet seal 13w (second seal member) are installed at optimum positions, and the developing roller 13a ( A surface layer 13w2 of the second inlet seal 13w facing the developer carrier is formed of a conductive material. As a result, the problem of toner scattering to the outside from the opening of the developing device 13 formed in the vicinity of the developing region is suppressed, and the toner accumulates or accumulates on the facing surface of the inlet case 13p (casing member) facing the developing roller 13a. It is possible to reliably reduce the problem that the toner drops.

  In the present embodiment, the present invention is applied to the trickle developing type developing device 13, but all other developing devices can be used as long as they use a two-component developer. The present invention can be applied to these developing devices. Even in this case, the same effect as that of the present embodiment can be obtained.

  Further, in the present embodiment, 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 the developing device 13 is a process cartridge.

  It should be noted that the present invention is not limited to the present embodiment, and it is obvious that the present embodiment can be modified as appropriate within the scope of the technical idea of the present invention, other than suggested in the present embodiment. is there. In addition, the number, position, shape, and the like of the constituent members are not limited to the present embodiment, and the number, position, shape, and the like suitable for implementing the present invention can be achieved.

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),
13c Doctor blade (developer regulating member),
13p inlet case (casing member),
13v first inlet seal (first seal member),
13w second inlet seal (second seal member),
13w1 base layer, 13w2 surface layer,
G developer (two-component developer), T toner, C carrier.

Japanese Patent No. 4280537

Claims (6)

A developing device that contains a developer having a carrier and toner and develops a latent image formed on the surface of an image carrier that travels in a predetermined direction.
A developer carrying member that forms a developing region facing the image carrier and carries a developer and travels in a predetermined direction;
A developer regulating member that forms a gap facing the developer carrying member and regulates the amount of developer carried on the developer carrying member;
The developer carrier is opposed to at least the position of the gap from the downstream side in the running direction of the developer carrier to the upstream side in the running direction of the developer carrier relative to the development region. A casing member formed as follows:
A first seal member that is flexible and has a root portion held by the casing member so that a tip end portion is in contact with a position on the upstream side in the running direction of the image carrier with respect to the development region. When,
A root portion is held on the facing surface of the casing member facing the developer carrying member, and a tip end portion of the developer carrying member is located upstream of the developing region in the running direction of the developer carrying member. A second seal member that hangs down by its own weight in the approaching direction and is placed in contact with the developer carried on the developer carrying body, and having flexibility,
With
The developing device according to claim 2, wherein the second seal member is formed of a conductive material on a surface layer facing the developer carrying member.   The developing device according to claim 1, wherein a voltage having the same potential as a developing bias applied to the developer carrier is applied to the surface layer of the second seal member.   The developing device according to claim 1, wherein the surface layer of the second seal member is made of aluminum.   The tip end portion of the second seal member is formed so as to be positioned closer to the developing region than the tip end portion of the first seal member. The developing device according to any one of the above. A process cartridge that is detachably installed on the main body of the image forming apparatus,
5. A process cartridge in which 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.

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