JPH0962094A - Developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stable image having high quality by uniformly bringing a layer thickness control member of developer into contact with the developer carrier surface. SOLUTION: A contact member 75 supported by a supporting member 77 of a layer thickness control member 70 fixed to a holder part 85 of a housing 80 in which the surface opposite to the developer carrier 60 is formed into a planner shape and the rear surface is formed into a projecting surface part by making the plate thickness of a lengthwise center part thicker, and a pressing member 88 fixed to the housing 80 in contact with the projecting surface part are provided, then the contact member 75 is pressed from the projecting part side. The contact member 75 is deformed by depressing the rear side center projecting part. Then, the pressing force is dispersed on the flat surface while depressing the projecting part of the contact member 75, and the surface of the developer carrier 60 is uniformly depressed to form the surface into a flat shape.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device of an image forming apparatus such as a copying machine, a facsimile machine, a printer, etc., and more specifically, it is for forming a developer on a developer carrying member in a uniform thin layer. This belongs to the improvement of the layer thickness regulating member.

[0002]

2. Description of the Related Art A layer thickness regulating member for forming a uniform thin layer of developer on a developer carrier of a developing device is disclosed in Japanese Patent Laid-Open No. 6-2.
It is disclosed in Japanese Patent No. 74019.

[0003]

An outline of the developing device of the disclosed image forming apparatus will be described (see FIG. 7). The layer thickness regulating member 10 for forming a thin layer of the developer on the developer carrying member includes a contact member 13 that abuts on the developer carrying member 20,
It comprises a support member 11 to which the contact member 13 is attached by adhesion or integral molding. The developer layer thickness regulating member 10 is a holder 35 for mounting the casing 30 of the developing device.
It is fixed by a fixing means such as a screw. Contact member 1
3 is configured to come into contact with the developer carrying member 20 to obtain a uniform pressing force in the axial direction of the developing carrier 20 due to the elasticity of the support member 11.

Here, the contact member 13 has a thickness D _{1 at the} central portion.
Is thicker in the width direction than the thickness D ₂ at both ends, and the central portion is a convex surface. Since the convex surface of the contact member 13 is opposed to the developer carrying member 20, the contact member 13 contacts the developer carrying member 20 with the contact pressure in the axial direction of the developer carrying member 20 from the end to the other. It will be more sensitive to the edges. This displacement of the contact pressure is not a big problem in the initial stage, but from the viewpoint of maintainability in long-term use, streaks on the developer carrier layer formation, image unevenness at the time of halftone such as photographs on printouts, etc. An inconvenience that causes The present invention, in a developing device for visualizing a latent image by adhering a latent image toner formed on an electrostatic latent image carrier, is stable by uniform contact of the developer layer thickness regulating member with the surface of the developer carrier. A developing device for obtaining high image quality is provided.

[0004]

A developing device for visualizing a latent image by adhering a developer to a latent image formed on an electrostatic latent image bearing member of the present invention is supported by a supporting member and carries a developer. The side surface that contacts the body is a flat surface, and the other side surface is thicker at the axial center of the developer carrier than at both ends, and the flat surface of the contact member that makes up the protrusion contacts the developer carrier. A layer thickness regulating member for regulating the amount of the developer on the developer carrying member, and a pressing member for contacting the convex portion of the contact member of the layer thickness regulating member to press the layer thickness regulating member toward the developer carrying member. It is equipped with. The pressing member of the layer thickness regulating member is fixed to the housing, or formed integrally with the supporting member of the contact member,
It has a configuration in which it is arranged parallel to the axis of the developer carrying member.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic sectional view showing a one-component developing device embodying the present invention and using a magnetic developer. The electrostatic latent image carrier 50 is a photoconductive drum having a surface layer made of a negatively charged organic photoconductor on the surface thereof, and is uniformly charged by a charging means (not shown), and then the electrostatic latent image is held. Is formed. The surface potential at this time is, for example, −
It can be 100V and -360V in the background.

The developer carrying member 60 is provided so as to face the electrostatic latent image holding member 50, and rotates to carry the developer adhering to the surface thereof. Then, at the position A (development area) close to the electrostatic latent image holding member 50, the gap between the developer carrying member 60 and the electrostatic latent image holding member 50 is set to be about 200 μm to 350 μm. Inside the developer carrier 60, a magnet shaft 66 is provided in which a plurality of magnets are arranged along the peripheral surface and are fixed and supported so as not to rotate. The magnet shaft 66 forms a magnetic pattern in which the S poles and N poles of a plurality of magnets are arranged along the circumferential surface,
According to this magnetic pattern, the magnetic developer is attracted to the surface of the developing sleeve 67 of the developer carrier 50.

The developer layer thickness regulating member 70 is a contact member 75 which is pressed against the surface of the developer carrying member 60, and a contact member 75.
And a support member 77 that is integrally formed with the. Contact member 75
Is a plate body made of an elastic material such as urethane rubber having a width of 15 mm, a thickness of 1.00 mm and a rubber hardness of 63 °. The contact member 75 has a flat side 750 on one side, and the other side located on the back side of the flat side 750 has a convex side surface 75 having a thick central portion.
5 is assumed. The projecting degree of the projecting portion of the convex side surface 755 is about 200 μm projecting from both end portions. A flat plate-shaped mounting portion 753 is formed on the convex side surface 755.

The supporting member 77 is a galvanized steel plate having a thickness of 1 mm, and the first supporting portion 771 for supporting the contact member 75.
And a second support portion 773 fixed to the holder portion 85 of the housing 80 formed by being connected to the first support portion 771. The first support portion 771 of the support member 77 is fixed to the attachment portion 753 of the contact member 75, the second support portion 773 is fixed to the holder portion 85, and the contact member 75 is fixed to the housing 80.
It is fixedly supported inside. The contact member 75 is brought into contact with the developer carrying member 60 by bringing the flat plate surface 750 into contact with the surface of the developer carrying member 60. Then, the contact position P of the contact member 75
Is the angle θ between the position where the developer carrying member 60 is closest to the electrostatic latent image holding member 50 (the position indicated by A) and the reference line R connecting the axis of the magnetic shaft 66 and the contact position P. The angle θ = 5 ° is formed on the downstream side in the rotation direction of the developer carrier 60. Then, the free end of the contact member 75 is installed so as to face the upstream side in the rotation direction of the developer carrier 60.

The housing 80 of the developing device stores the magnetic one-component developer to be supplied to the developer carrier 60, and also houses the developer carrier 60. The surface of the developer carrier 60 is exposed at the portion where the housing 80 opens toward the electrostatic latent image carrier 50, and the developer carrier 60 and the electrostatic latent image carrier 50 are arranged close to each other. To be done. A high voltage AC power supply 90 and a DC power supply 95 apply a DC superimposing AC power supply, which is a bias voltage, to the developer carrier 60, and in the developing area A where the developer carrier 60 and the electrostatic latent image carrier 50 are close to each other, An alternating electric field is generated between the surface of the electrostatic latent image carrier 50 and the grounded electrode under the photoreceptor layer. This bias voltage has, for example, an AC component frequency of 2.4 KHZ, a peak-to-peak voltage of 2000 V,
The DC component can be -250V. Alternatively, only a DC component may be applied.

When the developing device develops the electrostatic latent image on the electrostatic latent image holder 50, the developer in the developing device housing 80 is adsorbed on the surface of the rotating developer carrier 60. Then, the contact member 75 of the layer thickness regulating member 70 rubs the surface of the developer carrying body 60, so that the developer on the developer carrying body 60 is thinned and an appropriate electric charge is applied to the developer. .
The thinned developer is conveyed to the developing area A by the rotation of the developer carrier 60, and has an appropriate electric charge in the alternating electric field generated in the gap between the developer carrier 60 and the electrostatic latent image carrier 50. Many developer particles having a number of particles fly and reciprocate. Also, due to this reciprocating motion, the particles of the developer collide with each other,
The entire developer becomes cloud-shaped. The developer cloud is formed by the electrostatic latent image holder 5 by the DC component of the bias voltage.
The development is completed by being attracted to the latent image portion above 0.

Next, the structure and function of the layer thickness regulating member 70 of the developing device of the present invention will be described with reference to FIG. The plate-shaped contact member 75 made of a soft elastic body has a flat plate surface 750 facing the position where the developer carrying member 60 is arranged, and the pressing plate 88 of the contact member 75 arranged in the housing 80 in parallel with the holder portion 85. And the convex side surface 755 are brought into contact with each other. At this time, since the convex side surface 755 of the contact member 75 has a plate thickness difference of approximately 200 μm between the both end portions and the central protruding portion, the pressing plate 8
8 and the contact member 75 at both ends, a gap H of a difference in plate thickness.
Is formed. The support member 77 made of a galvanized steel plate or the like to which the contact member 75 is attached is attached to a holder portion 85 formed in the developing device housing 80 made of ABS with screws or the like.

The development carrier 60 is attached to the housing 80 having the contact member 75 thus formed attached thereto so as to press the flat plate surface 750 of the contact member 75. At this time, the gap H between both ends of the convex side surface 755 of the contact member 75 and the central protrusion disappears. That is, the central part of the contact member 75 is deformed by the pressing of the pressing plate 88, and the pressing force is dispersed on the flat plate surface 750 to be crushed to form a flat plate. Then, the developer carrier 60 that contacts the flat plate surface 750 of the contact member 75.
Will obtain uniform pressure from the contact member 75 in the axial direction, which is the contact surface of the contact member 75. For example, in this embodiment, the contact member 75 has a developer carrier 60 of 50 g / cm.
Will be pressed evenly.

As described above, since the toner adsorbed on the developer carrier 60 makes a line contact with the contact member 75 of the layer thickness regulating member 70 by a uniform pressing force, a uniform layer can be formed and the toner charge amount is uniform. Becomes As a result, unevenness in halftone of printed paper is eliminated, and stable image quality can be maintained.

Next, another example of the mounting portion of the pressing plate is shown in FIG. The pressing plate 880 connects the contact member 75 to the housing 8
The support member 770 attached to the holder part 85 of No. 0 is integrally provided. The pressing plate 880 is fixed to the arms 885 hanging from both ends of the supporting member 770. The pressing plate 880 is arranged so as to contact the convex surface portion 755 of the contact member 75. In the layer thickness regulating member thus configured, the pressing plate is integrally formed and can be attached to and detached from the developing device, so that the assembly operability is improved.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view of a developing device of the present invention.

FIG. 2 is a perspective view of a contact member.

FIG. 3 is a perspective view of a main part of the developing device.

FIG. 4 is a top view of the contact member when the contact member is not in contact with the development carrier.

FIG. 5 is a top view of the contact member when the contact member contacts the development carrier.

FIG. 6 is a perspective view showing another embodiment of the developing device.

FIG. 7 is a perspective view of a conventional developing device.

FIG. 8 is a top view of a conventional contact member.

[Explanation of symbols]

50 electrostatic latent image carrier, 60 developer carrier, 66
Magnetic shaft, 67 developing sleeve, 70 developer layer thickness regulating member, 75 contact member, 77 supporting member,
85 mounting holder, 80 developing device casing, 88 pressing member, 90 high-voltage AC power supply, 95
DC power supply, 750 flat plate surface, 755 convex surface portion.

Claims (4)

[Claims] 1. An electrostatic latent image bearing member comprising: a layer thickness regulating member for regulating the amount of developer on the developer bearing member; and a pressing member for pushing the layer thickness regulating member toward the developer bearing member. In a developing device that visualizes a latent image by attaching a developer to the formed latent image, the layer thickness regulating member has a contact member that contacts the developer carrier and a support member that supports the contact member. Is a flat surface on the side that comes into contact with the developer carrier, and the other side is thicker than the plate thickness on both ends of the developer carrier axially central portion to form a convex portion, and the pressing member is the contact member. A developing device arranged in contact with the convex portion. 2. The developing device according to claim 1, wherein the pressing member of the layer thickness regulating member is fixed to the housing and is arranged parallel to the axis of the developer carrying member. 3. The developed image value according to claim 1, wherein the pressing member of the contact member is formed integrally with the support member of the contact member. 4. The contact surface of the contact member of the layer thickness regulating member is parallel to the developer carrying member at least when not in contact with the developer carrying member.
The developing device described.