JPH0980903A - Developing device for image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain a position relation between a developer regulation mem ber and a developer carrier to be constant and to form an excellent image by supporting the developer regulation member by a supporting member attached at the rigid surface member of the developer carrier. SOLUTION: A developing roller (developer carrier) 3 is provided with a mandrel and a magnetic cylinder as the rigid surface member composed of a piece of stainless steel whose surface is coated with plastic magnetic material incorporating ferrite, and an elastic body is provided between the mandrel and the magnetic cylinder. Also, the blade (developer regulation means) 4 is supported by an arm member (supporting member) 45 so as not to change the position relation between the magnetic cyliner and the blade 4, and is fixed at a supporting case 2. Thus, the magnetic cylinder of the developing roller 3 and the blade 4 are integrated through the arm member 45, so that the position relation between them is prevented from being changed.

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 an image forming apparatus such as a copying machine, a facsimile, and a printer.
Specifically, a developer carrier that carries a developer for developing a latent image formed on a latent image carrier of an image forming apparatus, and a developer regulation that regulates the amount of the developer carried on the developer carrier. And a developing device of an image forming apparatus having a member.

[0002]

2. Description of the Related Art Conventionally, as a developing device of this type, an image forming device for developing a latent image on the surface of a latent image bearing member by bringing a developer bearing member having a rigid surface into contact with the latent image bearing member. Developing devices are known. In this developing device, the developer regulating member regulates the amount of the developer carried on the developer carrying member, so that there is no variation in the amount of the developer on the surface of the developer carrying member, and a good developing operation is performed.

However, in such a developing device,
The rigid latent image carrier and the rigid developer carrier come into contact with each other, and the developer passes through the contacted portion. Therefore, the toner of the developer is crushed in this portion, and the developer in the crushed state is finally used for image formation, which may deteriorate the quality of the formed image.

In order to solve such an adverse effect, a rigid surface member that comes into contact with the latent image carrier, a shaft portion used for assembling to the housing portion, and the rigid surface member and the shaft portion are provided. A developer carrier having an elastic body provided between them may be used. If such a developer carrying member is used, the rigid surface member comes into contact with the latent image carrying member via the elastic member, so that an excessive force may be applied between the latent image carrying member and the rigid surface member. The developer is not broken by the force. Therefore, it is possible to prevent the deterioration of the image quality due to the crushing of the developer. The technique of forming the dielectric layer and the insulating layer of the developer bearing member with an elastic material is disclosed in, for example, Japanese Patent Application Laid-Open No. 57-114163.

[0005]

However, if the elastic body as described above is provided as the developer carrying member, a new problem arises. That is, in such a developing device, the developer regulating member is attached to the device casing independently of the developer carrying member. Therefore, when a developer carrying member having an elastic member is used, it may not be possible to keep the positional relationship between the rigid surface member of the developer carrying member and the developer regulating member constant. The amount of developer on the body surface is no longer well regulated. As described above, when the amount of the developer on the surface of the developer bearing member is not properly regulated and the amount of the developer on the surface becomes uneven, the amount of the developer used for the subsequent image forming operation becomes unstable. On the contrary, the image quality is deteriorated.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a rigid surface member that comes into contact with a latent image carrier, a shaft portion used for mounting to a housing portion,
Further, in the developing device of the image forming apparatus using the developer carrying member provided with the elastic body provided between the rigid surface member and the shaft portion, the positional relationship between the developer regulating member and the developer carrying member is fixed. A developing device for an image forming apparatus capable of forming a good image by preventing deterioration of image quality due to the amount of the developer on the surface of the developer carrier becoming unstable due to the fact that the image cannot be kept in To provide.

[0007]

In order to achieve the above object, the developing device according to claim 1 is arranged so as to contact the surface of a latent image carrier on which a latent image is formed. A developer carrying member carrying on its surface a developer for developing
An image forming apparatus comprising: a developer regulating member that regulates the amount of the developer carried on the developer carrying body, wherein the developer carrying body is a rigid surface in contact with the latent image carrying body. The developer, which has a member, a shaft portion used for assembling to the housing portion, and an elastic body provided between the rigid member and the shaft portion, and which is attached to the rigid member. The present invention is characterized in that a support member is provided for supporting the restriction member so that the positional relationship with the rigid member does not change.

In the developing device according to claim 1, since the developer regulating member is attached by the supporting member attached to the rigid surface member of the developer carrying member, even if the developer carrying member moves, it does not move. Along with this, the developer regulating member supported by the supporting member also moves. Therefore, the positional relationship between the developer regulating member and the latent image carrier is always kept constant.

Further, the invention of claim 2 carries on its surface a developer for developing the latent image, which is arranged so as to contact the surface of the latent image carrier on which the latent image is formed. An image forming apparatus provided with a developer carrying member and a developer regulating member arranged so as to be in pressure contact with the developer carrying member for regulating the amount of the developer carried on the developer carrying body. And
A rigid surface member in which the developer carrying member abuts the latent image carrying member, a shaft portion used for assembling to the housing portion, and elasticity provided between the rigid member and the shaft portion. It is characterized in that it has a body, and a portion of the developer regulating member that comes into contact with the developer carrying body has a curved shape.

In the developing device according to the second aspect, the curved portion of the developer regulating member (hereinafter referred to as the curved portion) is brought into pressure contact with the latent image carrier. Therefore, even if the positional relationship between the developer carrying member and the developer regulating member changes to some extent,
The pressed state of the curved surface portion with respect to the developer carrying member does not change so much. Therefore, the regulation of the amount of the developer carried on the surface of the developer carrying member can be satisfactorily carried out almost as well as before. That is, contact failure between the two members due to a change in the positional relationship between the developer carrying member and the latent image developing agent controlling member occurs, for example, when the portion of the developer controlling member in contact with the developer carrying member has a sharp edge shape. Therefore, even after the positional relationship between both members has changed, the amount of the developer carried on the developer carrying member can be well regulated.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION

[First Embodiment] A first embodiment in which the present invention is applied to a developing device of an electrophotographic copying machine (hereinafter referred to as a copying machine) which is an image forming apparatus will be described below. FIG. 1 is a front view showing a schematic configuration of the developing device according to the present embodiment. This developing device includes a cylindrical photosensitive drum 1 as a latent image carrier.
A support case 2 as a housing which is disposed on the side of the housing and has an opening formed toward the photosensitive drum 1, and a magnetic toner (hereinafter referred to as “toner”) as a developer, a part of which is exposed from the opening. A developing roller 3 serving as a developer carrying member, a blade 4 serving as a developer regulating member that is carried on the developing roller 3 to regulate the layer thickness of the magnetic toner, and frictionally charges the toner. A mini-agitator 5 as a toner supply member for supplying the toner in the toner hopper 6 as a container to the developing roller 3 is provided. Inside the toner hopper 6, there is provided an agitator 7 for conveying the toner to the mini agitator 5 side. The conductive shaft of the photoconductor drum is grounded.

The developing roller 3 will be further described.
The developing roller 3 is provided in contact with the photosensitive drum 1 in the developing area as shown in FIG. That is, the entire developing device is pressed in the direction of the arrow shown in FIG. 1 by a pressing means (not shown) such as a spring, so that the developing roller 3
Contacts the photosensitive drum 1.

FIG. 2 is a sectional view showing the structure of the developing roller 3. As shown in FIG. 2, the developing roller 3 includes a metal core 34 as a shaft portion and a magnetic cylinder 32 as a rigid surface member made of stainless steel having a surface coated with a ferrite-containing plastic magnetic material 31. The toner is held by magnetizing the surface thereof in the axial direction. Since the developing roller 3 is provided with the cylindrical member 32 made of stainless steel, it can be magnetized with high magnetic force and is hard to break as compared with the developing roller having no such member. An elastic body 33 is provided between the cored bar 34 and the magnetic cylinder 34. As the elastic body 33, a material having an Asker C hardness of about 40 degrees and an electric resistance of about 1 × 10 ⁶ Ωcm is used.

Regarding the structure for assembling the blade 4,
Description will be added with reference to FIGS. 1, 2 and 3. FIG. 3 is an explanatory diagram showing the arm member 45, and FIG. 4 is an explanatory diagram showing how the blade 4 is assembled to the apparatus main body using the arm member 45. As shown in FIGS. 1 and 3, the blade 4 is assembled on the opposite side of the apparatus by an arm member 45 as a support member that supports the blade 4 so that the positional relationship between the magnetic cylinder 32 and the blade 4 does not change. That is, after the arm members 45 are loosely fitted to the cored bar 34 from both ends thereof (see FIG. 4A), each arm member 45 is attached to the magnetic cylinder 32.
Both arm members 45 fitted in the
The blade 4 is attached to the holder via the holder 4a. Then, the blades 4 are assembled by fixing the integrated arm members 45 and the blades 4 to the support case 2.

According to this assembly structure, the arm member 45
Since the magnetic cylinder 32 and the blade 4 are integrated with each other, the positional relationship between the two does not change. Further, the arm member 45 is fitted into the magnetic cylinder 32 by such fitting that the magnetic cylinder 32 can rotate. Therefore, even if the blade 4 is fixed to the support case 2, the rotation of the developing roller 3 is not hindered.

In this copying machine constructed as described above, the toner is supplied from the toner hopper 6 to the developing roller 3 by the agitator 7 and the mini agitator 5. This toner is magnetically held by the developing roller 3 which rotates in the same direction as the photosensitive drum 1 at a speed three times faster,
As a result, the layer thickness of the toner on the developing sleeve 31 is regulated and frictionally charged. Then, the charged toner is conveyed to the developing area by the developing roller 3 and develops the latent image formed on the surface of the photosensitive drum 1 in the developing area. The developing bias is set to -650V DC,
It was applied to the core metal 34. However, as the applied voltage, alternating current, pulse voltage or the like can be used instead of direct current. Further, when the developing operation is performed, the blade 4 and the developing roller 3 are usually at the same potential, but a potential difference may be provided between the two members in order to inject a charge into the toner.

The amount of toner attached to the developing roller 3 is about 0.6 to 1.0 mg / cm ² , and the amount of toner charge is about -7.5 to 15 μc / g.

[Second Embodiment] A second embodiment in which the present invention is applied to an electrophotographic copying machine (hereinafter referred to as a copying machine) which is an image forming apparatus will be described below. It should be noted that this embodiment is different from the first embodiment in the shape and assembly structure of the blade 4, but is otherwise the same as the first embodiment. Therefore, description of the same points as in the first embodiment will be omitted, and only different points will be described.

FIG. 5 is a schematic configuration diagram of the copying machine according to the present embodiment. In this embodiment, as shown in FIG. 5, the blade 4 is fixed to the support case 2 via the holder 4a.
The blade tip portion 4b, which is a portion of the blade 4 that contacts the developing roller 3, has a curved shape. In the illustrated example, the blade tip 4a is bent to form a curved shape, but the tip 4b may be polished to form a curved shape.

According to this embodiment, even if the positional relationship between the photosensitive drum 1 and the developing roller 3 changes to some extent, that is,
Even if the amount of protrusion of the blade 4 changes a little, the pressure contact state of the tip end portion 4b having a curved surface shape with respect to the photosensitive drum 1 does not change so much. Therefore, the regulation of the amount of the developer carried on the photoconductor drum 1 can be satisfactorily performed almost in the same manner as before. FIG. 6 is a graph showing the relationship between the amount of protrusion of the blade and the amount of toner attached to the developing roller 3 in this embodiment. Note that r shown in the graph is the diameter of the developing roller. From this graph, it can be read that the amount of toner adhering to the developing roller 3 hardly changes when the amount of protrusion of the blade is in the range of −r / 5 to 0.

[0021]

According to the invention of claim 1, even if the developer carrying member moves, the developer regulating member also moves in accordance with the movement. Therefore, the positional relationship between the developer regulating member and the latent image carrier is It is always kept constant. Therefore, since the positional relationship cannot be maintained constant, the quality of the image finally formed does not deteriorate due to the amount of the developer on the surface of the developer carrier being not regulated well. , A good image is formed.

Further, according to the second aspect of the invention, even if the positional relationship between the developer carrying member and the developer regulating member is slightly changed, the pressure contact state of the curved surface portion with respect to the developer carrying member does not change so much, and the development is performed. The regulation of the amount of the agent will be well realized. Therefore, the quality of the image finally formed does not deteriorate due to the fact that the amount of the developer on the surface of the developer bearing member is not regulated well, and a good image is formed.

[Brief description of drawings]

FIG. 1 is a front view showing a schematic configuration of a developing device according to a first embodiment.

FIG. 2 is a sectional view showing a structure of a developing roller of the developing device.

FIG. 3 is an explanatory view showing an arm for assembling a blade to the developing device.

FIG. 4A and FIG. 4B are explanatory views showing how a blade is assembled in the developing device.

FIG. 5 is a front view showing a schematic configuration of a developing device according to a second embodiment.

FIG. 6 is a graph showing the relationship between the blade protrusion amount and the amount of toner attached to the developing roller in the developing device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoconductor drum (latent image carrier) 2 Support case 3 Developing roller (developer carrier) 4 Blade (developer regulating member) 5 Mini agitator 6 Toner hopper 7 Agitator 31 Plastic magnetic body 32 Magnetic cylinder (rigid surface member) 33 Elastic body (elastic body) 34 Core metal (shaft portion) 45 Arm member (support member)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Akira Sawada Akira Sawada 1-3-6 Nakamagome, Ota-ku, Tokyo Ricoh Co., Ltd. (72) Hiroshi Saito 1-3-6 Nakamagome Ota-ku, Tokyo Shares Company Ricoh

Claims (2)

[Claims] 1. A developer carrying member, which is provided so as to contact a surface of a latent image carrier on which a latent image is formed, and which carries a developer for developing the latent image on the surface thereof, An image forming apparatus comprising: a developer regulating member that regulates the amount of the developer carried on the developer carrying body, wherein the developer carrying body is a rigid surface member in contact with the latent image carrying body; The developer regulation, which has a shaft portion used for assembling to a casing portion, and an elastic body provided between the rigid member and the shaft portion, and which is attached to the rigid surface member. A developing device for an image forming apparatus, comprising: a supporting member that supports a member so that a positional relationship with the rigid surface member does not change. 2. A developer carrying member, which is provided so as to come into contact with the surface of a latent image carrier on which a latent image is formed, and which carries a developer for developing the latent image on the surface thereof, An image forming apparatus comprising: a developer regulating member that is arranged so as to be pressed against a developer bearing body and regulates the amount of the developer carried on the developer bearing body. The carrier has a rigid surface member that comes into contact with the latent image carrier, a shaft portion used for assembling to the housing, and an elastic body provided between the rigid member and the shaft portion. In addition, the developing device of the image forming apparatus is characterized in that a portion of the developer regulating member that comes into contact with the developer carrying member has a curved shape.