JP6237292B2 - Developing device, process cartridge, and image forming apparatus - Google Patents

Description

  The present invention relates to a developing device that develops a latent image formed on an image carrier, and a process cartridge and an image forming apparatus including the developing device, and in particular, faces a developer carrier on the upstream side of a development region. The present invention relates to a developing device, a process cartridge, and an image forming apparatus in which a casing member is installed.

  2. Description of the Related Art Conventionally, in a developing device installed in an image forming apparatus using an electrophotographic system such as a copying machine, a printer, a facsimile, or a composite machine thereof, a developer carrier (developing roller) is provided upstream of a developing area. In order to prevent the problem that toner accumulates in the casing member that is installed so as to cover, and to prevent the problem that the toner scatters from the opening in the vicinity of the developing region, the image carrier is brought into contact with the front end side of the casing member. A technique is disclosed in which a first seal member is attached and a second seal member made of a conductive material is attached to an opposing surface of the casing member (see, for example, Patent Document 1).

  On the other hand, in Patent Document 2, a seal member that contacts the image carrier is attached to the front end side of a casing member that is installed so as to cover the developer carrier on the upstream side of the development region. A technique for forming a coating layer containing a catalyst for decomposing ozone on the surface is disclosed.

In the technique of Patent Document 1 described above, the first seal member that contacts the image carrier is attached to the front end side of the casing member, and the second seal member made of a conductive material is attached to the opposite surface of the casing member. Therefore, it is possible to greatly expect the effect of preventing the toner from being accumulated in the casing member and preventing the toner from being scattered from the opening in the vicinity of the developing region.
However, in the technique disclosed in Patent Document 1, when the second seal member made of a conductive material comes into contact with the image carrier, the latent image formed on the image carrier is electrically disturbed, resulting in an image quality. There was a possibility of affecting. Moreover, since the technique of patent document 1 has stuck two sealing members on the casing member, the assembly | attachment property was not favorable or the casing member was enlarged.

  The present invention has been made to solve the above-described problems, the casing member does not increase in size, the assembling property is relatively good, and the problem that toner accumulates in the casing member is reduced, and 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 toner is scattered from an opening in the vicinity of a developing region is reduced.

  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, and is a development region facing the image carrier. A developer carrying member that carries the developer and travels in a predetermined direction, and a developer that controls the amount of the developer carried on the developer carrying member so as to face the developer carrying member A regulating member, and at least the developer regulating member from the downstream side in the running direction of the developer carrier to the upstream side in the running direction of the developer carrier from the downstream side in the running direction with respect to the development region And a casing member formed so as to face the developer carrier through a flexible seal member, and the seal member has a tip portion in the development region. The position on the upstream side in the running direction of the image carrier A portion that contacts at least the entire area of the image carrier of the image carrier and a surface layer that faces the developer carrier are formed of an insulating material. An intermediate layer made of a conductive material is provided to face the developer carrier through a surface layer so that the intermediate layer contacts the image carrier or a non-image area of the developer carrier. It is formed.

  According to the present invention, the casing member is not increased in size, the assembling property is relatively good, the problem of toner collecting in the casing member is reduced, and the toner is scattered from the opening near the developing region. It is possible to provide a developing device, a process cartridge, and an image forming apparatus that are alleviated.

1 is an overall configuration diagram illustrating an image forming apparatus according to an embodiment of the present invention. It is sectional drawing which shows an image formation part. FIG. 3 is a cross-sectional view showing an AA cross section of the developing device in the image forming unit of FIG. 2. (A) an enlarged cross-sectional view showing a portion corresponding to the image area of the photosensitive drum, and (B) an enlarged cross-sectional view showing a portion corresponding to the non-image area of the photoconductive drum, which are main parts of the developing device It is. It is the schematic which shows a photoconductor drum and a sealing member in a longitudinal direction. The main part of the developing device as Modification 1 is (A) an enlarged sectional view showing a part corresponding to the image area of the photosensitive drum, and (B) a part corresponding to the non-image area of the photosensitive drum. It is an expanded sectional view shown. FIG. 10 is an enlarged cross-sectional view illustrating a main part of a developing device as a second modification and corresponding to a non-image area of a photosensitive drum.

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, 1 is a color printer as an image forming apparatus, 2 is a writing unit that emits laser light L based on image information, and 20Y, 20M, 20C, and 20BK correspond to each color (yellow, magenta, cyan, and black). The process cartridge 21 is a photosensitive drum as an image carrier housed in each of the process cartridges 20Y, 20M, 20C, and 20BK, 22 is a charging unit that charges the photosensitive drum 21, and 23Y, 23M, 23C, and 23BK are A developing device (developing unit) that develops the electrostatic latent image formed on the photosensitive drum 21, and a transfer bias roller (transfer unit) 24 that transfers the toner image formed on the photosensitive drum 21 to the intermediate transfer belt 27. And 25, a cleaning unit for collecting untransferred toner on the photosensitive drum 21.

  In addition, 27 is an intermediate transfer belt on which toner images of respective colors are transferred in an overlapping manner, 28 is a second transfer bias roller for transferring the toner image formed on the intermediate transfer belt 27 to the transfer material P, and 29 is an intermediate transfer belt. 27 is an intermediate transfer belt cleaning unit that collects untransferred toner, 30 is a transfer belt that conveys a transfer material P onto which four color toner images are transferred, and 32Y, 32M, 32C, and 32BK are developing devices 23Y. , 23M, 23C, and 23BK, a toner replenishing unit that replenishes toner of each color, 61 a paper feeding unit that accommodates a transfer material P such as transfer paper, and 66 a fixing that fixes an unfixed image on the transfer material P Part.

Here, each of the process cartridges 20Y, 20M, 20C, and 20BK is obtained by integrating the photosensitive drum 21, the charging unit 22, and the cleaning unit 25, respectively. The process cartridges 20Y, 20M, 20C, and 20BK are exchanged with respect to the apparatus main body 1 in a predetermined exchange cycle. Similarly, the developing devices 23Y, 23M, 23C, and 23BK are also exchanged with respect to the apparatus main body 1 in a predetermined exchange cycle.
Image formation of each color (yellow, magenta, cyan, black) is performed on the photosensitive drum 21 in each of the process cartridges 20Y, 20M, 20C, and 20BK.

Hereinafter, an operation during normal color image formation in the image forming apparatus will be described.
First, the surface of the photosensitive drum 21 is uniformly charged at a position facing the charging unit 22 (charging process). Thereafter, the surface of the charged photosensitive drum 21 reaches the irradiation position of each laser beam L.

  On the other hand, in the writing unit 2, a laser beam L corresponding to the image signal is emitted from the light source corresponding to each color. The laser light L is incident on the polygon mirror 3 and reflected, and then passes through the lenses 4 and 5. The laser light L after passing through the lenses 4 and 5 passes through different optical paths for each of the yellow, magenta, cyan, and black color components (this is an exposure process).

The laser beam L corresponding to the yellow component is reflected by the mirrors 6 to 8 and then irradiated to the surface of the photosensitive drum 21 of the first process cartridge 20Y from the left side of the drawing. At this time, the yellow component laser light L is scanned in the direction of the rotation axis (main scanning direction) of the photosensitive drum 21 by the polygon mirror 3 that rotates at high speed. Thus, an electrostatic latent image corresponding to the yellow component is formed on the photosensitive drum 21 charged by the charging unit 22.
Similarly, the laser beam L corresponding to the magenta component is reflected by the mirrors 9 to 11 and then irradiated to the surface of the photosensitive drum 21 of the second process cartridge 20M from the left side of the paper, thereby electrostatically corresponding to the magenta component. A latent image is formed. The cyan component laser light L is reflected by the mirrors 12 to 14 and then irradiated onto the surface of the photosensitive drum 21 of the third process cartridge 20C from the left side of the paper, thereby forming an electrostatic latent image of the cyan component. The black component laser light L is reflected by the mirror 15 and then irradiated to the surface of the photosensitive drum 21 of the fourth process cartridge 20BK from the left side of the paper, thereby forming an electrostatic latent image of black component.

Thereafter, the surface of the photosensitive drum 21 on which the electrostatic latent images of the respective colors are formed further rotates to reach positions facing the developing devices 23Y, 23M, 23C, and 23BK, respectively. Then, the respective color toners are supplied from the developing devices 23Y, 23M, 23C, and 23BK onto the photosensitive drum 21, and the latent image on the photosensitive drum 21 is developed (this is a developing step).
Thereafter, the surface of the photosensitive drum 21 after the development process reaches a position facing the intermediate transfer belt 27. Here, the transfer bias roller 24 is installed at each facing position so as to contact the inner peripheral surface of the intermediate transfer belt 27. Then, the image of each color formed on the photosensitive drum 21 is sequentially transferred onto the intermediate transfer belt 27 at the position of the transfer bias roller 24 (first transfer step).

Then, the surface of the photosensitive drum 21 after the first transfer process reaches a position facing the cleaning unit 25. The untransferred toner remaining on the photosensitive drum 21 is collected by the cleaning unit 25 (this is a cleaning process).
Thereafter, the surface of the photosensitive drum 21 passes through a static elimination unit (not shown), and a series of image forming processes on the photosensitive drum 21 is completed.

On the other hand, the surface of the intermediate transfer belt 27 on which the images of the respective colors on the photosensitive drum 21 are transferred in an overlapping manner travels in the direction of the arrow in the drawing and reaches the position of the second transfer bias roller 28. Then, the full color image on the intermediate transfer belt 27 is secondarily transferred onto the transfer material P at the position of the second transfer bias roller 28 (second transfer step).
Thereafter, the surface of the intermediate transfer belt 27 reaches the position of the intermediate transfer belt cleaning unit 29. Then, the untransferred toner on the intermediate transfer belt 27 is collected by the intermediate transfer belt cleaning unit 29, and a series of transfer processes on the intermediate transfer belt 27 is completed.

Here, the transfer material P at the position of the second transfer bias roller 28 is transported from the paper feeding unit 61 via the transport guide 63, the registration roller 64, and the like.
Specifically, the transfer paper P fed by the paper feed roller 62 from the paper feed unit 61 that stores the transfer material P is guided to the registration roller 64 after passing through the conveyance guide 63. The material P to be transferred that has reached the registration roller 64 (timing roller) is conveyed toward the position of the second transfer bias roller 28 in synchronization with the toner image on the intermediate transfer belt 27.

Thereafter, the transfer material P onto which the full color image has been transferred is guided to the fixing unit 66 by the transfer belt 30. In the fixing unit 66, the color image is fixed on the transfer material P at the nip between the heating roller 67 and the pressure roller 68.
Then, the transfer material P after the fixing process is discharged as an output image outside the apparatus main body 1 by the paper discharge roller 69, and a series of image forming processes is completed.

Next, the image forming unit of the image forming apparatus will be described in detail with reference to FIGS.
FIG. 2 is a cross-sectional view showing the image forming unit, and FIG. 3 is a cross-sectional view taken along line AA showing the developing device 23.
The four image forming units installed in the apparatus main body 1 have substantially the same structure except that the color of the toner T used in the image forming process is different. Therefore, the alphabet of reference numerals in the process cartridge, the developing device, and the toner replenishing unit. (Y, M, C, BK) is removed for illustration.

  As shown in FIG. 2, the process cartridge 20 mainly contains a photosensitive drum 21 as an image carrier, a charging unit 22, and a cleaning unit 25 integrally in a case 26. The cleaning unit 25 is provided with a cleaning blade 25 a and a cleaning roller 25 b that are in contact with the photosensitive drum 21.

  The developing device 23 (developing unit) mainly includes a developing roller 23a as a developer carrying member that forms a developing region facing the photosensitive drum 21, and a first transport screw 23b (first transport member) facing the developing roller 23a. ), The second conveying screw 23c (second conveying member) facing the first conveying screw 23b via the partition member 23e, and the amount of developer G carried on the developing roller 23a facing the developing roller 23a are regulated. A doctor blade 23d as a developer regulating member, a toner concentration sensor 23g for detecting the toner concentration of the developer G in the developing device 23, and the like. In the developing device 23, a two-component developer G composed of carrier C and toner T is accommodated. Referring to FIG. 3, the developing roller 23a includes a magnet body 23a1 fixed inside to form a plurality of poles (magnetic poles) on the roller outer peripheral surface, and a sleeve 23a2 rotating around the magnet body 23a1. Composed.

The above-described image forming process will be described in more detail with a focus on the developing process.
The developing roller 23a rotates (runs) in the direction of the arrow in FIG. As shown in FIG. 3, the developer G in the developing device 23 is generated by the rotation of the first conveying screw 23 b and the second conveying screw 23 c arranged so as to interpose the partition member 23 e therebetween in the arrow direction. It circulates in the longitudinal direction while being agitated and mixed with the toner T replenished from the replenishing part 32 through the replenishing port 23f (circulation in the direction of the broken arrow in FIG. 3).
Then, the toner T that is frictionally charged and adsorbed on the carrier C is pumped onto the developing roller 23a together with the carrier C by the agent pumping pole formed on the developing roller 23a. The developer carried on the developing roller 23a is conveyed in the direction of the arrow in FIG. 2 and reaches a position facing the doctor blade 23d. The developer on the developing roller 23aY is conveyed to a position facing the photosensitive drum 21 (development region) after the developer amount is made appropriate at this position. The toner is attracted to the latent image formed on the photosensitive drum 21 by the electric field formed in the development area. Thereafter, the developer remaining on the developing roller 21a reaches above the first conveying screw 23b as the sleeve rotates, and is detached from the developing roller 21a at this position. Here, the electric field in the development region is generated by a predetermined voltage (development bias) applied to the development roller 23a by a power supply unit (not shown) for development, the charging process, and the exposure process. And a surface potential formed on the surface.

  A plurality of poles are formed by the magnet body 23a1 on the outer peripheral surface of the sleeve 23a2 of the developing roller 23a. Specifically, the magnet body 23a1 includes three N-pole magnet portions and two S-pole magnet portions. By these magnet portions, a developer pumping electrode for pumping the developer G onto the developing roller 23a, a transport pole for transporting the developer G carried on the developing roller 23a to the doctor blade 23d, and the developer G A magnetic force distribution including a transport pole for transporting to the development area, a main electrode formed in the development area, and an agent separation pole for separating the developer G after passing through the development area from the development roller 23a It is formed on 23a. Due to the magnetic force distribution, the developer G moves on the developing roller 23a as the sleeve 23a2 rotates.

  Here, the toner replenishing unit 32 provided in the apparatus main body includes a replaceable toner bottle 33, a toner hopper unit 34 that holds and rotates the toner bottle 33, and replenishes the developing device 23 with fresh toner T. , Is composed of. The toner bottle 33 contains toner T (any one of yellow, magenta, cyan, and black). In addition, a spiral protrusion is formed on the inner peripheral surface of the toner bottle 33.

The toner T in the toner bottle 33 is appropriately replenished into the developing device 23 from the replenishing port 23f as the toner T in the developing device 23 is consumed. Consumption of the toner T in the developing device 23 is detected by a toner concentration sensor 23g that magnetically detects the toner concentration of the developer G in the device 23 (the ratio of the toner T in the developer G). In the present embodiment, the toner concentration of the developer G in the developing device 23 is controlled to be 5 to 9% by weight.
The replenishing port 23f is provided at one end in the longitudinal direction of the second transport screw 23c (the left-right direction in FIG. 3) and above the second transport screw 23c.

Hereinafter, the configuration and operation of the developing device 23, which are characteristic in the present embodiment, will be described in detail with reference mainly to FIGS.
As shown in FIG. 4 (or FIG. 2), the developing device 23 in the present embodiment is opposed to the developing roller 23a (developer carrier) with a predetermined gap (doctor gap). A doctor blade 23d (developer regulating member) is installed. The doctor blade 23d is a substantially plate-like member made of a metal material such as stainless steel or aluminum for restricting the developer G carried on the developing roller 23a to an appropriate amount and performing the developing process. . The doctor blade 23d is screwed to the developing case 23h through a long hole whose longitudinal direction is the vertical direction, and is configured so that the size of the doctor gap can be adjusted.

In this embodiment, at least the doctor blade 23d faces the developing roller 23a (the position of the doctor gap) from the downstream side in the running direction of the developing roller 23a with respect to the developing region. A casing member 23i (development inlet cover) formed so as to face the developing roller 23a through a flexible seal member 23j (development inlet seal) is installed up to a position upstream in the running direction. Yes. Specifically, referring to FIG. 4 (or FIG. 2), a casing member 23i is installed on the downstream side of the doctor blade 23d so as to face the developing roller 23a. The casing member 23i is formed of aluminum, a resin material, or the like, and the front end portions 23j4 and 23j5 protrude on the photosensitive drum 21 side on the facing surface (the surface facing the developing roller 23a). A seal member 23j having a three-layer structure is attached.
The casing member 23i is developed together with the doctor blade 23d so as to come into contact with the downstream side wall surface of the doctor blade 23d (the wall surface that meets the developing roller 23a on the downstream side in the running direction of the developing roller 23a). Screwed to the case 23h.

Here, with reference to FIGS. 4A, 4B, and 5, the seal member 23j has its leading end portions 23j4 and 23j5 upstream in the running direction of the photosensitive drum 21 with respect to the developing region (upstream in the rotational direction). Side) position. As a result, the problem of toner scattering from the opening in the vicinity of the development area can be reliably reduced.
In the present embodiment, the seal member 23j is in contact with the photoconductive drum 21 in the counter direction so that the front end portions 23j4 and 23j5 of the seal member 23j are along the rotation direction of the photoconductive drum 21. The problem that the seal member 23j is caught or twisted by the rotation of the photosensitive drum 21 is suppressed.

Further, the seal member 23j has at least a portion of the front end portions 23j4 and 23j5 that contacts the entire area of the image region M of the photosensitive drum 21 (the image region front end portion 23j4) and a surface layer 23j1 that faces the developing roller 23a. Are formed of an insulating material, and are further formed with an intermediate layer 23j2 made of a conductive material, facing the developing roller 23a via the surface layer 23j1. Further, the intermediate layer 23j2 is a non-image area N of the photosensitive drum 21 (a longitudinal area where no image can be formed regardless of the size of the recording medium P to be passed, etc.). It is formed so that it may contact the area | region outside.
Specifically, the seal member 23j is formed such that the intermediate layer 23j2 is exposed to a portion (non-image region tip portion 23j5) that directly contacts the non-image region N of the photosensitive drum 21 in the tip portions 23j4 and 23j5. ing. Then, the intermediate layer 23j2 is formed so as to be covered with an insulating material except for a portion (non-image region tip portion 23j5) in contact with the non-image region N of the photosensitive drum 21. The potential of the intermediate layer 23j2 is equal to the potential (surface potential) of the non-image area N of the photosensitive drum 21.

  Specifically, the sealing member 23j in the present embodiment also has a base layer 23j3 attached to the casing member 23i, and the base layer 23j3 covers the intermediate layer 23j2 so that it is not exposed to the casing member 23i side. It has been broken. That is, the intermediate layer 23j2 is exposed to the outside by the base layer 23j3, the front end portion 23j4, and the surface layer 23j1 except for the non-image region front end portion 23j5 that is exposed to the photosensitive drum 21 side and contacts the non-image region N. Covered not to. In other words, in the sealing member 23j, the intermediate layer 23j2 made of a conductive material is in a layer made of an insulating material except for the non-image region tip portion 23j5 (base layer 23j3, image region tip portion 23j4, surface layer 23j1). It is a flexible sheet member having a three-layer structure formed so as to be sandwiched between the two.

More specifically, in the present embodiment, the seal member 23j has a base layer 23j3 made of an insulating Mylar material having a layer thickness of about 0.01 to 0.03 mm (a developed view as viewed from above has a substantially convex shape. The intermediate layer 23j2 having a layer thickness of about 0.01 to 0.03 mm made of a conductive material such as copper is formed on the top (development viewed from above is substantially concave). And a surface layer 23j1 made of a Mylar material having an insulating property with a thickness of about 0.01 to 0.03 mm on the intermediate layer 23j2 (the developed view as viewed from above is substantially convex). And the top end of the base layer 23j3 and the top end of the surface layer 23j1 are bonded to each other so that the intermediate layer 23j2 is not exposed. , A non-image area tip 23j5 intermediate layer 23j2 is exposed, is formed.
In this embodiment, the three layers 23j1 to 23j3 are bonded to form the three-layer seal member 23j. However, the three layers 23j1 to 23j3 are sequentially stacked by vapor deposition to form a three-layer seal member. 23j can also be formed. In that case, the vapor deposition process is performed using a mold in which the surface layer 23j1 and the base layer 23j3 are not formed at the non-image region distal end portion 23j5.

Then, the exposed intermediate layer 23j2 (non-image area front end portion 23j5) is in contact with the non-image area N on the surface of the photosensitive drum 21, and the intermediate layer 23j2 is maintained at the same potential as the surface potential of the non-image area N. become.
Specifically, in the present embodiment, in the non-image area N of the photosensitive drum 21, an electric field is formed between the developing roller 23a and an electric field that prevents the toner T from moving electrically from the developing roller 23a side. Charged. That is, since the non-image area N of the photosensitive drum 21 is an area where an image is not originally planned to be formed, the charging potential (toner) in the charging process without being irradiated with the laser beam L in the exposure process. Is maintained, and the intermediate layer 23j2 becomes the same potential as the charging potential (non-image portion potential) via the non-image region front end portion 23j5, and the toner T becomes the sealing member 23j. It becomes difficult to adhere to.
On the other hand, the image region M of the photosensitive drum 21 is irradiated with the laser beam L in the exposure process after the charging process according to the image to be formed, and the toner T is electrically applied from the developing roller 23a side. The moving electric field is charged so as to be formed between the developing roller 23a (the surface potential of the black portion changes to the plus side with respect to the developing bias). Therefore, if the intermediate layer 23j2 is configured to come into contact with the image area M of the photosensitive drum 21, an electric field is generated so that the toner T does not move electrically from the developing roller 23a side to the intermediate layer 23j2. The toner T is positively attached to the seal member 23j. Further, if the intermediate layer 23j2 is configured so as to be in contact with the image region M of the photosensitive drum 21, the potential of the intermediate layer 23j2 is not stable.

  Specifically, the toner T used in the present embodiment is a negatively charged toner, and −600 V is supplied from the developing power supply unit (not shown) to the developing roller 23a during a normal developing process. About a developing bias is applied. The photosensitive drum 21 (non-image area N) is controlled so that the potential difference from the developing bias is about −150 V in the charging process. That is, as described above, when a developing bias of −600 V is applied to the developing roller 23a, the charging process is performed so that the surface potential of the non-image area N of the photosensitive drum 21 is about −750V, and the intermediate A voltage of about −750 V is also applied to the layer 23j2.

As a result, the toner T in the developer G carried on the developing roller 23a at the position facing the seal member 23j stays on the developing roller 23a side without being electrically attracted to the casing member 23i side. Therefore, the problem that toner accumulates on the casing member 23i (seal member 23j) side is surely reduced.
In the present embodiment, the intermediate layer 23j2 is not provided with a power supply unit for applying a voltage to the intermediate layer 23j2, and the intermediate layer 23j2 is not subjected to special power application control for the intermediate layer 23j2. Since the electric field is formed so that the toner T does not move from the developing roller 23a side to the seal member 23j side while maintaining the same potential as that of the non-image area N, the structure is relatively inexpensive and simple. .

In the present embodiment, the tip 23j4 (the tip of the image area) of the seal member 23j that contacts the photosensitive drum 21 in the image area M is formed of an insulating material, and thus is formed of a conductive material. Unlike the case where the intermediate layer 23j2 is in direct contact with the image area M of the photosensitive drum 21, the electrostatic latent image formed on the photosensitive drum 21 is electrically disturbed, which affects the image quality. Defects are reliably reduced.
In particular, when the layer formed of the conductive material is configured to directly contact the image area M of the photosensitive drum 21 or to face the developing roller 23a, the photosensitive drum 21 and the developing roller 23a. As a result of sliding contact with the developer G carried thereon, irregularities are formed on the surface of the layer formed of the conductive material, and the convex portions act like an electrical antenna to act as a photosensitive drum 21. Since the upper electrostatic latent image is easily disturbed, and the electric field formed between the developing roller 23a and the seal member 23j is likely to be disturbed, the configuration in this embodiment is useful.
In the present embodiment, since one seal member 23j having a function of preventing toner scattering and a function of preventing toner accumulation is adhered to the casing member 23i, the toner is Compared with the case where the first seal member having the function of preventing scattering and the second seal member having the function of preventing toner accumulation are separately attached to the casing member, the assembling property is improved and the casing member is improved. 23i can be prevented from increasing in size and shape.

  In the present embodiment, the sealing member 23j has at least a surface layer 23j1 and tip portions 23j4 and 23j5 having a low-friction material (more It is preferably made of an abrasion resistant material. For example, the surface layer 23j1 of the seal member 23j and the image region tip 23j4 are coated with an insulating fluorine material, and the non-image region tip 23j5 of the seal member 23j is coated with a conductive fluorine material. You can also.

In this embodiment, the seal member 23j has a three-layer structure including a base layer 23j3 (insulating layer), an intermediate layer 23j2 (conductive layer), and a surface layer 23j1 (insulating layer). However, the base layer 23j3 is not necessarily formed. 6A and 6B, the tip 23j4 and the surface layer 23j1 are made of an insulating material so that the portion of the intermediate layer 23j2 corresponding to the image region M is not exposed in the seal member 23j. As long as it is formed.
In the example of FIG. 6, as shown in FIG. 6A, the opposite surface of the intermediate layer 23 j 2 and the tip of the intermediate layer 23 j 2 corresponding to the image region M (image region tip 23 j 4) are covered. A surface layer 23j1 made of an insulating material is formed to be folded at the image region front end portion 23j4. Then, as shown in FIG. 6B, the non-image area front end portion 23j5 of the intermediate layer 23j2 is directly exposed to the non-image area N of the photosensitive drum 21 at both ends in the longitudinal direction. 6A and 6B, the back surface of the intermediate layer 23j2 (the surface on the opposite side of the facing surface on which the surface layer 23j1 is formed) is directly on the casing member 23i. It is stuck.
Even in such a case, the above-described effects of the present invention are exhibited.

In the present embodiment, the intermediate layer 23j2 of the seal member 23j is in contact with the non-image area N of the photosensitive drum 21 (image carrier), and the intermediate layer 23j2 is the same as the non-image area N of the photosensitive drum 21. It comprised so that it might become an electric potential.
On the other hand, the intermediate layer 23j2 of the seal member 23j comes into contact with the non-image area of the developing roller 23a (developer carrier) so that the intermediate layer 23j2 has the same potential as the developing bias applied to the developing roller 23a. It can also be configured. That is, as shown in FIG. 7, the seal member 23j is a non-image of the developing roller 23a via the relay member 23n formed of a conductive material at the end in the longitudinal direction corresponding to the rotation axis direction of the developing roller 23a. The intermediate layer 23j is formed so as to be in indirect contact with the region, and is covered with the front end portions 23j4 and 23j5 formed of an insulating material and the surface layer 23j1, and the potential of the intermediate layer 23j2 is set to the developing roller 23a. It can be configured to be equivalent to the potential (development bias). In the example of FIG. 7, a leaf spring member (for example, the intermediate layer 23j2) in which a part of the side surface on one end side in the longitudinal direction of the intermediate layer 23j2 and the end surface in the shaft portion on one end side in the longitudinal direction of the developing roller 23a are electrically conductive. The side is a fixed end, and the developing roller 23a side is a free end so as to be slidable. In the example of FIG. 7, the tip portions 23j4 and 23j5 of the seal member 23j are formed of an insulating material over the entire longitudinal direction.
In such a case, a voltage having the same potential as the voltage (development bias) applied to the developing roller 3a is applied to the intermediate layer 23j2 of the seal member 23j, and the polarity of the toner T is positively applied. Although the toner T does not move electrically to the developing roller 23a side, the toner T does not move electrically to the casing member 23i side, so that the toner accumulates on the casing member 23i (sealing member 23j) side. Can be reduced. That is, if the voltage difference between the developing bias and the voltage applied to the intermediate layer 23j2 is 0 V or less with respect to the toner T having a negative polarity, the toner accumulates on the casing member 23i (seal member 23j) side. It can be reduced.
The reason why the intermediate layer 23j2 and the non-image area of the developing roller 23a are brought into contact with each other is that if the intermediate layer 23j2 and the image area of the developing roller 23a are brought into contact with each other in the image area carried on the developing roller 23a. This is because the amount of the developer G fluctuates and a good development process cannot be performed. Furthermore, in order to ensure electrical connection between the intermediate layer 23j2 and the developing roller 23a, it is preferable that the intermediate layer 23j2 is brought into contact with a portion where the developer G is not carried in the non-image area of the developing roller 23a.

  As described above, in the present embodiment, the seal member 23j has its leading end portions 23j4 and 23j5 in contact with the position upstream of the developing direction of the photosensitive drum 21 (image carrier) with respect to the development region. The surface layer 23j4 (image region tip) that is installed and contacts at least the entire area of the image region M and the surface layer 23j1 that faces the developing roller 23a (developer carrier) are formed of an insulating material. The intermediate layer 23j2 (non-image area front end 23j5) is a part of the non-image area N of the photosensitive drum 21. The intermediate layer 23j2 is opposed to the developing roller 23a through 23j1 and is formed of a conductive material. Or it is formed so that all may be contacted. As a result, the casing member 23i on which the seal member 23j is installed is not increased in size, the assemblability is relatively good, the problem of toner collecting in the casing member 23i is reduced, and the opening near the developing region is reduced. The problem of toner scattering is reduced.

In the present embodiment, the developing device 23 is configured separately from the process cartridge 20. On the other hand, the developing device 23 can be integrated with the process cartridge 20. Further, the developing device 23 is integrated with at least one of the photosensitive drum 21, the charging unit 22, the transfer unit 24, the cleaning unit 25, and the toner replenishing unit 32 to constitute a unit. It can also be detachably installed in the apparatus main body 1. In such a case, the same effect as in the present embodiment can be obtained, and the maintainability of the image forming unit is improved.
In the present application, the “process cartridge” refers to a charging unit that charges the image carrier, a developing device (developing unit) 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 configured to be detachable from the image forming apparatus main body.

In the present embodiment, the present invention is applied to the developing device 23 using the two-component developer G composed of the toner T and the carrier C. On the other hand, the present invention can also be applied to a developing device using a one-component developer composed only of toner (including external additives and the like).
In the present embodiment, the present invention is applied to the developing device 23 in which the casing member 23i is configured as a member different from the developing case 23h. However, the configuration of the casing member 23i is not limited thereto. For example, the present invention is also applied to the developing device 23 in which the casing member 23i is configured as one member integrally with the developing case 23h. Can do.
In such cases, the same effects as those of the present embodiment can be obtained.

In the present embodiment, the intermediate layer 23j2 of the seal member 23j is configured to be in contact with the non-image area N of the photosensitive drum 21 at both ends in the longitudinal direction. On the other hand, the intermediate layer 23j2 of the seal member 23j can be configured to contact the non-image region N of the photosensitive drum 21 only at one end portion in the longitudinal direction.
Even in such a case, the intermediate layer 23j2 contacts the non-image area N without contacting the image area M, and the intermediate layer 23j2 has the same potential as the non-image area N of the photosensitive drum 21, The same effect as that of the present embodiment can be obtained.

  It should be noted that the present invention is not limited to the present embodiment, and it is obvious that each embodiment can be modified as appropriate within the scope of the technical idea of the present invention, other than suggested in each 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 (image forming apparatus main body),
20, 20Y, 20M, 20C, 20BK Process cartridge,
21 Photosensitive drum (image carrier),
23, 23Y, 23M, 23C, 23BK Developing device (developing unit),
23a Development roller (developer carrier),
23b first conveying screw,
23c second conveying screw,
23d doctor blade (developer regulating member),
23h Development case,
23i casing member,
23j sealing member,
23j1 surface layer, 23j2 intermediate layer,
23j3 base layer,
23j4 tip (image region tip),
23j5 tip (non-image region tip),
23n Relay member.

JP 2013-117563 A JP 2010-176038 A

Claims (9)

A developing device for developing a latent image formed on the surface of an image carrier traveling in a predetermined direction,
A developer carrying member that forms a development region facing the image carrier and carries the developer and travels in a predetermined direction;
A developer regulating member that regulates the amount of developer carried on the developer carrying body opposite the developer carrying body;
At least the position where the developer regulating member faces the developer carrier from the downstream side in the running direction of the developer carrier to the position upstream in the running direction of the developer carrier relative to the development region A casing member formed so as to face the developer carrier via a flexible sealing member,
With
The seal member is disposed such that a tip portion thereof is in contact with a position on the upstream side in the running direction of the image carrier with respect to the development region, and at least the entire image region of the image carrier among the tip portions. And a surface layer facing the developer carrying member is formed of an insulating material, and an intermediate layer formed of an electrically conductive material is opposed to the developer carrying member via the surface layer. And a developing device wherein the intermediate layer is formed in contact with a non-image area of the image carrier or the developer carrier.   In the seal member, the intermediate layer is exposed to a portion of the tip portion that directly contacts a non-image area of the image carrier, and a portion of the intermediate layer excluding the contact portion is the insulating material. The developing device according to claim 1, wherein the developing device is formed so as to be covered with an intermediate layer, and the potential of the intermediate layer is equal to the potential of the non-image region of the image carrier.   The non-image area of the image carrier is charged such that an electric field is formed between the developer carrier and the developer carrier so that toner does not move electrically from the developer carrier side. The developing device according to claim 2.   The seal member indirectly contacts a non-image area of the developer carrier via a relay member formed of a conductive material at an end in a longitudinal direction corresponding to the rotation axis direction of the developer carrier. The intermediate layer is formed so as to be covered with the tip portion and the surface layer formed of an insulating material, and the potential of the intermediate layer becomes equal to the potential of the developer carrier. The developing device according to claim 1.   The developing device according to claim 1, wherein the surface layer and the tip end portion of the seal member are formed of a low friction material.   The said sealing member is equipped with the base layer stuck to the said casing member, The said intermediate | middle layer was covered with the said base layer so that it may not expose to the said casing member side. Item 6. The developing device according to Item 5.   The developing device according to claim 1, wherein the developer is a two-component developer having a carrier and a toner. A process cartridge that is detachably attached to the image forming apparatus main body,
8. A process cartridge comprising the developing device according to claim 1 and the image carrier integrally.   An image forming apparatus comprising the developing device according to claim 1 and the image carrier.

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