JP2003280372A - Developing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing device capable of preventing developer to be carried and fed from sticking to the surface of the end of the developer carrier by a resin layer formed on the surface of a developer carrier. <P>SOLUTION: A sealing member 60 preventing the developer from being leaked to the outside of a developing container 10 is arranged to slide in contact with the end surface 11a of a developing roller 11 so that it may be superposed on the resin layer 70 formed on the roller 11. Thus, a gap between the end 70a of the resin layer 70 on the roller 11 and the end 60a of the member 60 is covered with the member 60. As a result, the developer is prevented from sticking to the end surface 11a of the roller 11. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device for developing a latent image formed on a latent image carrier with a developer to make it a visible image. The present invention also relates to an image forming apparatus such as a copying machine, a facsimile, and a printer, which forms an image using the developing device.

[0002]

2. Description of the Related Art As a developing device of this type, Japanese Unexamined Patent Publication No. 2000
A developing device disclosed in Japanese Patent Publication No. 756331 is known. This developing device has a developing container for containing a developer, a developer carrier for carrying and carrying the developer, and a seal member for preventing the developer from leaking out of the developer container. The developer carrying member is rotatably supported by the developing container and carries and carries the developer toward the opening of the developer container. The seal member is fixedly arranged in the developing container so as to rub against the end surface of the developer carrying member in the rotation axis direction. The surface of the developer carrier of this developing device is blasted. The seal member is arranged so as to be in sliding contact with the end surface of the portion of the developer carrier that is out of the blasting region.

[0003]

By the way, in the above-mentioned conventional developing device, the developer is conveyed by the unevenness of the surface of the developer carrying member by the blast treatment. The irregularities on the surface of the developer carrying member due to this blasting process are worn and become smaller with time. For this reason, this conventional developing device has a problem that the amount of the developer carried by the developer carrying member decreases with time, and is poor in durability. Therefore, the present applicant has developed a developer carrier having a resin layer formed by coating the surface with a resin. In the developing device equipped with this developer carrying member, the developer is carried and conveyed by the electrostatic holding force of the resin layer of the developer carrying member. In this developing device, the decrease in the amount of developer conveyed with time, unlike the conventional developing device, is eliminated, and the durability is improved. Then, in order to prevent the developer carried by the resin layer from leaking to the outside of the developer container, the end surface of the part of the developer carrying member which is separated from the resin layer is removed in the same manner as the conventional developing device. The seal member was arranged so as to rub. As a result, it was possible to prevent the developer from entering between the end surface of the developer carrier and the sliding surface of the seal member. However,
When the seal member is arranged as in the conventional developing device, a gap is created between the seal member and the end portion of the resin layer, and a part of the end surface of the developer carrying member is exposed from this gap. Since the resin layer is not formed on the end surface of the developer carrier, the developer cannot be electrostatically held. Therefore, in the developing device having this configuration, the developer attached to the exposed portion of the end surface of the developer carrier is
This causes a problem that the developer drops from the end surface of the developer carrier and scatters out of the developing device.

The present invention has been made in view of the above problems. An object of the invention is to provide a developing device capable of preventing the developer carried by the resin layer formed on the surface of the developer carrier from being attached to the end surface of the developer carrier.

[0005]

In order to achieve the above-mentioned object, the invention of claim 1 is a developing container for accommodating a developer,
A developer carrier that is rotatably supported by the developer container and carries and conveys the developer toward the opening of the developer container, and is in sliding contact with the end surface of the developer carrier in the rotation axis direction. A developing device having a seal member that is fixedly arranged in the developer container and prevents the developer carried and carried by the developer carrier from leaking to the outside of the developer container. The developer carrying surface carrying the developer is formed of a resin layer covering the surface of the developer carrying body so as to expose the end surface of the developer carrying body in the rotation axis direction. It is characterized in that the seal member is arranged so as not to create a gap with the seal member. In this developing device, the entire surface of the end surface of the developer carrying member in the rotation axis direction is covered with the seal member, and no gap is formed between the seal member and the resin layer. This prevents the developer from adhering to the end surface of the developer carrier. The invention of claim 2 is
2. The developing device according to claim 1, wherein a part of the seal member is arranged so as to overlap with the resin layer, and a thickness of the resin layer in a part overlapping with the seal member is larger than a thickness of a resin layer in another part. It is characterized by being made smaller. According to a third aspect of the present invention, in the developing device according to the first or second aspect, a conveying force for supporting and conveying the surface roughness of an end surface of the developer carrier, which is not covered with the resin layer, is used. It is characterized in that the roughness is set so as not to generate. According to a fourth aspect of the present invention, in the developing device according to the first, second or third aspect, the developer carrying member is composed of a conductive member. Claim 5
In the developing device according to claim 1, 2, 3 or 4, the invention is characterized in that the developer is a one-component developer composed of a fine powdery solid. According to a sixth aspect of the present invention, a latent image carrier on which a latent image is formed, latent image forming means for forming a latent image on the latent image carrier, and a latent image formed on the latent image carrier are developed. An image forming apparatus having a developing unit that develops a visible image by using a developing agent is characterized in that the developing unit according to claim 1, 2, 3, 4 or 5 is used as the developing unit.

[0006]

DETAILED DESCRIPTION OF THE INVENTION An image forming apparatus to which the present invention is applied will be described below. FIG. 1 shows a schematic configuration of a printer as the image forming apparatus. This printer includes a photosensitive belt 1 as a latent image bearing member that is wound around a plurality of support rollers. In FIG. 1, the photosensitive belt 1 is rotationally driven in the clockwise direction indicated by the arrow A. A charger 3, an optical writing unit 4, four sets of developing devices 5Bk, 5C, 5M, and 5Y, an intermediate transfer belt 6 as an intermediate transfer member, a photosensitive member cleaning device 7, and the like are arranged around the photosensitive belt 1. ing. An organic photosensitive layer is formed on the surface of the photosensitive belt 1. When the image forming operation (printing operation) is executed by the printer, a high voltage is applied to the charger 3 so that the photosensitive belt 1 is uniformly charged. Then, in the image signal processing unit (not shown),
Color image information, for example, a color 4 image signal sent from an external computer is converted into an optical writing signal and sent to the optical writing unit 4. In the optical writing unit 4, a laser as a light source (not shown) is controlled based on the optical writing signal. The laser is Black (Bk), Cyan (C), and Magenta through the polygon mirror 8, the f / θ lens 9 and the reflection mirror 10.
Optical writing corresponding to the image signals of (M) and Yellow (Y) is performed. As a result, an electrostatic latent image is formed on the photosensitive belt 1. The electrostatic latent image on the photoconductor belt 1 has developing devices 5BK and 5BK each having a toner of each color as a developer charged with an electric charge having a polarity opposite to that of the latent image.
It is developed for each color by C, 5M and 5Y. As a result, a toner image is formed on the photosensitive belt 1 for each color.

A cam 50, which is independently rotatable, is in contact with the side ends (left side in the drawing) of the developing devices 5Bk, 5C, 5M, and 5Y. The rotation of the cam 50 causes the developing roller 11 to move to a position separated from the photosensitive belt 1 during non-developing. Then, when the electrostatic latent image on the photosensitive belt 1 is developed, the cam 50 is moved by a drive control unit (not shown).
It is driven to rotate by 80 degrees. As a result, for example, when the Bk electrostatic latent image on the photosensitive belt 1 is developed, the developing device 5Bk
The cam 50 located at the rear portion is driven to rotate by 180 degrees, and the developing device 5Bk is pushed out to the photosensitive belt 1 side.
Then, the developing roller 11Bk moves to the developing position where it contacts the photosensitive belt 1. Other color developing devices 5C, 5
The same applies to M and 5Y.

At the contact portion between the photosensitive belt 1 and the intermediate transfer belt 6, by applying an electric charge having a polarity opposite to that of the toner to the intermediate transfer belt 6, the toner image on the photosensitive belt 1 is transferred onto the intermediate transfer belt 6. Is transcribed to. By repeating this toner image formation and transfer operation four times, a four-color superposed color toner image is formed on the intermediate transfer belt 6.
The color toner image on the intermediate transfer belt 6 is transferred from the paper feed cassette 40 or the manual feed tray 41 to the conveyance roller pair 42.
Is transferred by a paper transfer roller 43 as a secondary transfer member onto the transfer paper as a recording material sent by
The transfer paper on which the color toner image is transferred is a fixing roller pair 4
Then, the toner image is fused and fixed.

Next, the developing devices 5Bk, 5C, 5M and 5Y used in the printer will be described. Figure 2
An example of a developing device having a configuration common to the developing devices 5Bk, 5C, 5M, and 5Y is shown in FIG. This developing device is a one-component developing type developing device using a non-magnetic one-component toner (hereinafter referred to as "toner") as a developer. This developing device has a developing container 10 having an opening toward the photoconductor belt 1 and a developing roller 11 as a developer carrying member. Further, the toner supply roller 12 that supplies toner onto the developing roller 11, and the transport paddle 17 that sends out the toner stored in the toner storage portions 18a, 18b, and 18c in the developing container 10 to the supply roller 12 side.
It has a, 17b, and 17c. Further, it has a regulating roller 14 as a developer layer regulating member for abutting on the developing roller 11 and regulating the layer thickness of the toner carried on the developing roller to form a toner layer having a predetermined layer thickness. . The developing roller 11 is partially exposed from the opening of the developing container 10,
It is installed so as to rotate counterclockwise at a predetermined linear velocity during development. The developing roller 11 carries the toner on the roller surface and conveys the toner to a developing position, which is a contact portion with the photosensitive belt 1, and develops the latent image formed on the photosensitive belt 1. The toner supply roller 12 is in contact with the developing roller 11 with a predetermined pressure. The surface of the toner supply roller 12 is made of foamed polyurethane. Further, a toner regulating blade 13 is in contact with the toner supply roller 12. The toner regulating blade 13 is the developing roller 11
It is configured to regulate the amount of toner supplied to the. Each transport paddle 17 is installed rotatably in the counterclockwise direction of the arrow. The toner is sent to the supply roller 12 side by the rotation of each of the transport paddles 17. Each transport paddle 17
As the material of, a soft and elastic material such as polypropylene can be used. Utilizing its elasticity, each of the transport paddles 17 rotates while being in close contact with the inner wall of the developing container 10 to reliably transport the toner. The regulation roller 14 regulates the toner on the developing roller 11 to a predetermined layer thickness, and frictionally charges the toner by slidingly contacting the toner. The charged toner on the developing roller 11 develops the electrostatic latent image on the photosensitive belt 1. In this developing device, urethane rubber coated with resin is used as the material of the surface portion of the regulation roller 14. A regulation roller cleaning blade 16 is in contact with the regulation roller 14. The regulation roller cleaning blade 16 cleans the surface of the regulation roller 14 that has passed the contact portion with the developing roller 11. Further, a spring 19 is provided as an urging means for bringing the regulating roller 14 into contact with the developing roller 11. Further, on the inner surface of the developing container 10, an inlet seal 15 is provided as an inlet seal member that extends so that the tip of the developing roller 11 contacts the surface of the developing roller 11.

FIG. 3 to FIG. 5 show an example of the construction of the main part of the above-mentioned developing device, which is common to the embodiments described later. 3 to 5, those having the same configurations and functions as those of the constituent elements of the developing device shown in FIG. 2 are designated by the same reference numerals as those of the constituent elements of the developing device shown in FIG. And its description is omitted. The developing device according to each embodiment includes a seal member 60 for preventing the toner carried and conveyed by the developing roller 11 from leaking out of the developing container 10. As shown in FIGS. 3 to 5, the sealing member 60 is fixedly arranged in the developing container 10 so as to be in sliding contact with the end surface 11a of the developing roller 11 in the rotation axis direction. Further, the developing roller 11 of the developing device according to each embodiment has a resin layer 70 formed by coating a resin on the surface thereof (see FIG. 4). The developing roller 10 can carry and convey toner by the electrostatic holding force of the resin layer 70. However, the resin layer 7 of the developing roller 11
When the seal member 60 is arranged so as to be in sliding contact with the end surface 11a of the portion deviated from 0, the seal member 60 and the resin layer 7
A gap is created between the two and zero. Then, a part of the end surface 11a of the developing roller 11 is exposed from this gap. The end surface 11a of the developing roller 11 has a resin layer 7
Since 0 is not formed, the toner cannot be electrostatically held. Therefore, the seal member 60 is
In the developing device having the arrangement described above, there is a problem that the toner attached to the exposed portion of the end surface 11a of the developing roller 11 drops and scatters. This problem can be solved by using the developing device according to each of the embodiments described below. Among the constituent elements of the developing device according to the following embodiments, those having the same configurations and functions as those of the constituent elements of the developing device shown in FIGS.
The same reference numerals are given to the respective constituent elements in FIGS. 3 to 5, and the description thereof will be omitted.

(Embodiment 1) The developing device according to Embodiment 1 has the following features in addition to the configuration of the developing device shown in FIGS. FIG. 6 shows an example of the developing device according to the first embodiment. This developing device includes an end portion 70 a of the resin layer 70 of the developing roller 11 and an end portion 60 a of the seal member 60.
And the seal member 60 so as not to create a gap between
Are arranged. Specifically, as shown in FIG. 6, the end portion 70a of the resin layer 70 of the developing roller 11 and the end portion 60a of the seal member 60 are configured to overlap each other by the distances a and b. Where the distances a and b
Is preferably in the range of 0 to 2 mm. That is,
When the distances a and b exceed the range of 0 to 2 mm, the toner that has entered between the seal member 60 and the resin layer 70 is melted by the sliding friction and fixed to the developing roller 11 due to the repetition of the developing operation. Sometimes. Then, the regulation roller 14 is formed by the toner fused and fixed to the developing roller 11.
May be pushed down, and the contact failure between the developing roller 11 and the regulation roller 14 may occur, which may cause toner scattering. Therefore, as a result of various experiments, the present inventor found out that the melt fixation of the toner to the developing roller 11 can be eliminated by setting the distances a and b within the range of 0 to 2 mm. That is, from this experiment, the distances a and b at which the seal member 60 and the resin layer 70 overlap each other are 0 to 2
By reducing the size to mm, heat generation during the developing operation is reduced. Thereby, the seal member 60 and the resin layer 7
It was found that the toner melt-fixing does not occur in the portion where 0 and 0 overlap. By the way, in this experiment, the axial width of the seal member 60 was set to 15 mm. It should be noted that the toner is not melted and fixed on the end surface 11a of the developing roller 11. The reason is that the end surface 1 of the developing roller 11 is
1a basically has no toner holding power, so the resin layer 7
This is because the toner is less likely to adhere and the heat generated due to the rubbing between the seal member 60 and the toner is less than that in the case of 0. Here, as the resin material of the resin layer 70 of the developing roller 11,
A non-contaminating material that does not contaminate the latent image carrier such as the photosensitive belt 1 is selected. Examples of such resin material include urea resin, melamine resin, alkyd resin, and modified alkyd resin such as phenol-modified or silicone-modified. Further, acrylic resin, silicone resin, fluororesin, phenol resin, polyamide resin, epoxy resin, polyester resin, maleic acid resin and the like can be mentioned. Among these resin materials, it is desirable to select urea resin, melamine resin, acrylic resin or the like from the viewpoint of film forming property and adhesiveness.

(Second Embodiment) The developing device according to the second embodiment has the following features in addition to the structure of the developing device according to the first embodiment. In the developing device according to the second embodiment, the thickness of the resin layer 70 in the portion overlapping the seal member 60 is made smaller than the thickness of the resin layer 70 in the other portions.
Specifically, as shown in FIG. 7, the film thickness c of the end portion of the resin layer 70 is made smaller than the film thickness e of the central portion. Further, in the region d having a smaller film thickness than the central portion, the distance b (and a) of the portion where the resin layer 70 and the seal member 60 overlap each other.
It is configured to be larger than. Here, the area d is
It is set outside the developing area of the latent image by the developing roller 11. Here, the smaller the film thickness of the resin layer 70, the lower the electrostatic toner holding force. The presence of the resin layer portion having no toner holding force inside the seal member 60 causes the toner to scatter due to the falling of the toner. Therefore, in the developing device according to the present embodiment,
The electrostatic holding force of the toner in this portion is reduced as long as it is possible to prevent the toner from being melted and fixed in the portion where the resin layer 70 and the seal member 60 overlap. Further, in the developing device according to the present embodiment, as shown in FIG. 7, the width of the region d is set to 3 mm, the film thickness e is set to 20 μm, and the film thickness c is set to 5 μm. Further, the resin layer in the region d is formed so that the film thickness is continuously changed, and the regulation roller 14 is formed.
It is prevented as much as possible that a step is formed at the contact portion between the resin layer 70 and the resin layer 70.

(Third Embodiment) In addition to the configuration of the developing device according to the first or second embodiment,
It has the following features. The developing device according to the third embodiment is
The surface roughness Rz of the end surface 11a of the developing roller 11 on which the resin layer 70 is not formed is set to be less than 1 μm. The end surface 11 of the developing roller 11
Compared to the resin layer 70, a has almost no carrying force for carrying and carrying toner. However, when the surface roughness Rz of the end surface 11a of the developing roller 11 becomes 1 μm or more,
A carrying force for carrying and carrying the toner is generated on the end surface 11a. The end surface 1 of the developing roller 11
When the carrying force for carrying and carrying the toner is generated on 1a, the toner comes into the sliding contact surface side of the seal member 60, and the toner is scattered to the outside of the seal member 60. The relationship between the surface roughness Rz of the end surface 11a of the developing roller 11 and the toner transporting property is that the amount of toner adhered due to the abrasion of the unevenness of the surface of the developing roller 11 that has been subjected to the conventional blast treatment. Can be understood from the decrease in

(Embodiment 4) The developing apparatus according to Embodiment 4 has the following characteristics in addition to the configuration of the developing apparatus according to Embodiment 1, 2 or 3. In the developing device according to the fourth embodiment, the base of the developing roller 11 on which the resin layer 70 is formed is
It is composed of a conductive member. As such a developing roller 11, for example, a metal roller such as an aluminum tube can be used.

(Embodiment 5) The developing device according to the fifth embodiment has the following features in addition to the structure of the developing device according to the first, second, third, or fourth embodiment. The developing device according to the fifth embodiment uses a one-component developer made of fine powdery solid, for example, toner, as a developer for developing the latent image formed on the photosensitive belt 1. The developing device using the one-component developer does not require a carrier, a toner concentration sensor, or the like, as compared with the developing device using the two-component developer, and thus has an advantage that it can be constructed at a low cost. However, since the developing device using the one-component developer cannot regulate the developer using magnetic force, unlike the developing device using the two-component developer, the sealing property of the developer cannot be improved. There are difficulties.

In the developing device according to the first embodiment, the end portion 70a of the resin layer 70 of the developing roller 11 and the seal member 6 are provided.
The gap between the zero end portion 60a and the end portion 60a is closed by the seal member 60. This prevents the developer from adhering to the end surface 11a of the developing roller 11. Also, this developing device
The toner is carried and conveyed by the electrostatic holding force of the resin layer 70 of the developing roller 11. As a result, unlike the conventional developing roller whose surface has been blasted, the toner conveyance amount does not decrease due to the abrasion of the surface irregularities over time, and the durability is improved. Further, by forming the overlapping width of the seal member 60 and the resin layer 70 of the developing roller 11 to be 0 to 2 mm, it is possible to suppress heat generation due to the sliding contact of the seal member 60. As a result, it is possible to prevent the toner from sticking to the developing roller 11 and prevent the toner from scattering over time. In particular, in the developing device according to the second embodiment, the electrostatic holding force at the end of the resin layer 70 can be reduced to prevent the toner from sticking and melting to the end of the resin layer 70. Also,
The heat generated due to the sliding contact of the seal member 60 can be further suppressed, and the toner fixation to the developing roller 11 can be prevented more reliably. In the developing device according to the third embodiment, the surface roughness R of the end surface 11a of the developing roller 11 is R.
By setting z to be less than 1 μm, the toner carrying force on the end surface 11a is reduced. As a result, it is possible to reliably prevent the toner from entering the sliding contact surface side of the seal member 60, and it is possible to prevent the toner from scattering to the outside of the seal member 60. Further, in the developing device according to the fourth embodiment, by using the developing roller 11 made of a conductive member, the developing bias can be easily applied to the developing roller 11. Further, since the end surface 11a of the developing roller 11 is not charged,
It becomes possible to prevent toner adhesion to the end surface 11a due to electrostatic force. Further, in the developing device according to the fifth embodiment, even when a one-component developer having a sealing problem is used, it is possible to prevent the one-component developer from leaking out of the developing container 10 as described above. Like As a result, the developing device can be constructed at low cost.

[0017]

According to the present invention, it is possible to prevent the developer carried by the resin layer formed on the surface of the developer carrier from being adhered to the end surface of the developer carrier. is there.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an example of an image forming apparatus to which the present invention is applied.

FIG. 2 is a schematic configuration diagram of a developing device used in the image forming apparatus.

FIG. 3 is a schematic configuration diagram of a main part of a developing device common to each embodiment of the present invention.

FIG. 4 is a schematic perspective view of a main part of the developing device shown in FIG.

5 is a schematic perspective view showing a seal member and a developing container of the developing device shown in FIG.

FIG. 6 is a schematic configuration diagram of a developing device according to the first embodiment of the present invention.

FIG. 7 is a schematic configuration diagram of a developing device according to a second embodiment of the present invention.

[Explanation of symbols]

1 photoconductor belt 3 charger 4 Optical writing unit 5Bk, 5C, 5M, 5Y Developing device 6 Intermediate transfer belt 10 developer container 11 Developing roller 11a End surface of developing roller 12 Toner supply roller 13 Toner regulation blade 14 Regulation roller 17a, 17b, 17c Transport paddle 18a, 18b, 18c toner container 60 seal member 60a End of seal member 70 Resin layer of developing roller 70a Edge of resin layer

Claims (6)

[Claims] 1. A developer container containing a developer, a developer carrier rotatably supported by the developer container and carrying and carrying the developer toward an opening of the developer container, and the developer carrier. And a seal member fixedly arranged in the developing container so as to be in sliding contact with the end surface of the rotation axis direction of the developer and preventing leakage of the developer carried and carried by the developer carrier to the outside of the developer container. In the developing device, the developer carrying surface of the developer carrying body carrying the developer is coated on the surface of the developer carrying body so as to expose the end surface in the rotation axis direction of the developer carrying body. A developing device comprising a resin layer, wherein the sealing member is arranged so as not to create a gap between an end portion of the resin layer and the sealing member. 2. The developing device according to claim 1, wherein a part of the seal member is arranged so as to overlap with the resin layer, and a thickness of the resin layer in a part overlapping with the seal member is set to a resin in another part. A developing device characterized by being made smaller than the layer thickness. 3. The developing device according to claim 1, wherein the surface roughness of the end surface of the developer carrier which is not covered with the resin layer produces a carrier force for carrying and carrying the developer. A developing device characterized by being set to have no roughness. 4. The developing device according to claim 1, 2, or 3,
The developing device, wherein the developer carrying member is formed of a conductive member. 5. The developing device according to claim 1, 2, 3 or 4, wherein the developer is a one-component developer made of fine powdery solid. 6. A latent latent image carrier on which a latent image is formed, latent image forming means for forming a latent image on the latent image carrier, and a latent image formed on the latent image carrier as a developer. An image forming apparatus comprising: a developing unit that develops into a visible image by using the developing unit according to claim 1, 2, 3, 4, or 5 as the developing unit.