JPH07121028A - Developing device - Google Patents

Abstract

PURPOSE:To prevent the deformation of a developing roller and the deterioration of image quality by providing a film member whose coefficient of friction with a one-component developer is larger than that of an elastic member with the one-component developer. CONSTITUTION:The plate-like elastic member 32 of a stainless steel plate. a phosphor bronze plate, etc.. is included and a dielectric film member 34 whose coefficient of friction with toner 14 is larger than that of the elastic member 32 with the toner 14 (desirably, the coefficient of friction in the toner 14) and wear resistance is excellent, such as urethane, silicone, nylon, etc., is fixed on the bottom surface of the elastic member 32 so as to project from its one end by using a joining material 35 such as an adhesive and a double coated tape. The other end of the elastic member 32 is fixed on a housing so that the film member 34 elastically comes into press-contact with the surface of the developing roller 24. Therefore, the pressing force of the elastic member 32 on the developing roller 24 can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device, and more particularly to a developing device for developing an electrostatic latent image formed on a surface of a photosensitive member by using, for example, a one-component developer.

[0002]

2. Description of the Related Art With reference to FIG. 8, in a conventional developing device 1, one end of a metal blade 2 is fixed to a developing tank 3 and the other end is elastically pressed against the surface of a developing roller 4, whereby The thickness of the one-component developer 5 attached to the surface of the developing roller 4 is regulated.

[0003]

In the conventional developing device 1, since the metal blade 2 having a small friction coefficient with the developer 5 is used, it is preferable if the pressing force of the blade 2 against the developing roller 4 is not increased. It is impossible to form a thin developer layer. However, when the pressing force of the blade 2 is increased, there is a problem that the developing roller 4 is permanently distorted and the image quality is deteriorated when the developing device 1 is left unused for a long period of time.

On the other hand, when rubber or resin having a large friction coefficient with the developer 5 is used as the material of the blade 2, the pressing force of the blade 2 against the developing roller 4 can be reduced, but if it is used for a long time, the blade is 2 is deformed, the pressing force is lowered, and the image quality is lowered. Further, in any of the above-mentioned conventional techniques, since the blade 2 needs to be pressed against the developing roller 4 at a predetermined pressure, the thickness of the blade 2 must be made relatively large. Therefore, for example, as shown in FIG. As described above, the developer 5 easily attaches to the tip portion of the blade 2 that is charged with the opposite polarity to the developer 5,
There is a problem that the image is disturbed due to the scattering of the developer 5.

Therefore, a main object of the present invention is to provide a developing device capable of preventing deterioration of image quality.

[0006]

SUMMARY OF THE INVENTION The present invention is directed to toner development of an electrostatic latent image formed on the surface of a photoconductor with a one-component developer, in which the one-component developer is stored. In a developing device including a developed developing tank, a developer carrier for supplying the one-component developer to the photoconductor, and a blade for controlling the thickness of the one-component developer attached to the developer carrier, the blade is free. A plate-shaped elastic member having an end and a part of the elastic member that is laminated and fixed to the elastic member so as to project forward from the free end, and has a friction coefficient with the one-component developer of the one-component developer of the elastic member. A developing device comprising a film member having a coefficient of friction larger than that of the friction member, and the film member being pressed against the developer carrying member by an elastic member.

[0007]

Since the film member having a large friction coefficient with the developer is pressed against the developing roller by the elastic member, the pressing force of the blade against the developing roller is relatively small even if a metal plate is used as the elastic member. You may Therefore,
It is possible to prevent distortion of the developing roller as in the prior art using a metal blade, and it is possible to prevent deformation of the blade as in the prior art using a rubber or resin blade. Since the tip of the film member is projected from the tip of the elastic member, the thickness of the tip of the blade becomes the thickness of the film member and is very thin. Therefore, it is possible to prevent the developer from adhering to the tip of the blade and prevent the image from being disturbed due to the scattering of the developer.

[0008]

According to the present invention, deterioration of image quality can be prevented. The above-mentioned objects, other objects, features and advantages of the present invention will become more apparent from the following detailed description of the embodiments with reference to the drawings.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The developing device 10 of this embodiment shown in FIG. 1 has one component for a latent image formed on the surface of a photosensitive drum (photosensitive plate, photosensitive belt or the like) 12 which is an electrostatic latent image carrier. A developer (toner) 14 is attached to form a visible image, and includes a housing 16. An accommodating container 18 for accommodating the toner 14 is arranged in an upper part of the housing 16, and a developing tank 22 having an opening 20 in a lower part thereof is formed inside the housing 16 and below the accommodating container 18. Further, a developing roller 24 as a developer carrying member that abuts on the photosensitive drum 12 and supplies the toner 14 to the photosensitive drum 12 is disposed in the opening 20, and inside the developing tank 22, the developing tank 22 is connected to the developing tank 22. The toner 14 supplied to the developing roller 24
A supply roller 26 for supplying to is disposed. A voltage applying device 28 is connected to the developing roller 24, and a blade 30 for regulating the thickness of the toner 14 attached to the surface of the developing roller 24 is provided in the opening 20.

2 and 3, the blade 30 includes a plate-shaped elastic member 32 such as a stainless plate or a phosphor bronze plate, and the lower surface of the elastic member 32 extends from one end of the elastic member 32 toward the front. And the coefficient of friction with the toner 14 is larger than the coefficient of friction between the elastic member 32 and the toner 14 (preferably the coefficient of friction between the toners 14), such as urethane, silicon, and nylon. A dielectric film member 34 having excellent wear resistance is fixed by using a bonding material 35 such as an adhesive or a double-sided tape.
The other end of the elastic member 32 is fixed to the housing 16 (FIG. 1) so that the film member 34 can be elastically pressed against the surface of the developing roller 24. The film member 3
The surface roughness of No. 4 is preferably 5 μm or less in Rz, and the material of the film member 34 is a pure material that does not contain a thermoplastic material or the like in order to prevent fusion of the toner 14. desirable. Further, the width d ₁ of the fixing region between the film member 34 and the elastic member 32 is preferably 5 mm or more in order to secure the fixing strength, and the width d _{2 of the} protruding portion is such that the edge portion of the film member 34 is developed. Roller 24
It is desirable that the thickness is 0.5 mm or more so as not to come into contact with and disturb the image. Further, in order to improve the flatness, the film member 34 may be laminated on the elastic member 32 by the integral molding or the hot melt method, so that the film member 34 and the elastic member 32 are joined together.

Returning to FIG. 1, such a developing device 10 is installed in an image forming apparatus such as a copying machine or a printer.
By the pressing device 36, the developing roller 24 is approximately 1 kgf to 3 kg.
It is pressed against the photoconductor drum 12 by the force of f, whereby
A suitable development nip (1-2 mm) is maintained in the development area 38. A charging device 40, a cleaning device 42, and the like are arranged around the photosensitive drum 12.

The developing device 10 can be applied to both the reversal development process in a printer or the like and the normal rotation development process in a copying machine or the like.
The reversal development process using the developing device 10 will be described. However, the photosensitive drum 12 is a negatively charged organic photosensitive drum, the toner 14 is a negatively charged non-magnetic toner containing styrene-acrylic resin as a main component, and a film member 34.
A urethane sheet having a wall thickness of about 0.1 mm was used as the.

When the developing roller 24 and the supply roller 26 are rotated in the arrow direction by a motor (not shown), the toner 14 is supplied to the developing roller 24 by the supply roller 26. At this time, frictional charging occurs between the toner 14 and the supply roller 26 and the developing roller 24, and the toner 14 is negatively charged. Here, if a conductive roller such as a conductive urethane foam laminated on a metal shaft is used as the supply roller 26, it is possible to prevent deterioration of the charging performance of the toner 14 due to overcharge. Developing roller 2
The toner 14 supplied to the toner No. 4 is regulated in thickness by the blade 30 to have a thin layer (10 μm to 30 μm) and is charged again by friction. As a result, the toner 14
Are further negatively charged, and the blade 30 (the film member 3
4) is positively charged. Then, the thinned toner 1
4 is conveyed to the developing area 38. On the other hand, the charging device 40 holds the surface potential of the photoconductor drum 12 at −700 V, and the surface of the photoconductor drum 12 is exposed by an optical writer (not shown) to form an electrostatic latent image on that portion. This electrostatic latent image is toner-developed in the developing area 38.

According to this embodiment, since the film member 34 having a large friction coefficient with the toner 14 is used, the pressing force of the elastic member 32 against the developing roller 24 can be reduced. Therefore, even when the developing roller 24 is not used for a long period of time, the problem that the developing roller 24 is deformed by the pressing force of the blade 30 (elastic member 32) does not occur. Further, since the film member 34 is provided so as to project forward from the end portion of the elastic member 32, the thickness of the tip portion of the blade 30 becomes the thickness (0.1 mm) of the film member 34, which is extremely thin. Therefore, the toner 14 is
Can be prevented from being attached, and the image can be prevented from being disturbed due to toner scattering or the like.

In the above embodiment, the film member 34 is fixed to the inner surface of the end of the elastic member 32. However, as shown in FIG. 4, the film member 34 is pressed against the developing roller 24. In the area A, the film member 3
4 may not be fixed to the elastic member 32. When the non-sticking area is provided in this way, that portion (area A)
In this case, since the bonding material 35 such as an adhesive or a double-sided tape is not interposed, the waviness of the film member 34 due to air (air bubbles) mixed in the bonding portion can be eliminated, and a better image can be obtained.

In the above embodiment, the vicinity of the edge portion 44 (FIG. 4) of the elastic member 32 is pressed against the developing roller 24 via the film member 34. However, as shown in FIG. Alternatively, the end portion of the elastic member 32 may be subjected to polishing treatment, and the polishing-treated surface 46 may be pressed against the developing roller 24 via the film member 34. In addition, FIG.
As shown in, the tip of the elastic member 32 is bent upward,
The bent portion 48 may be pressed against the developing roller 24 via the film member 34. As described above, when the polishing surface 46 (FIG. 5) and the bent portion 48 (FIG. 6) are brought into pressure contact with each other, burrs generated at the edge portion 44 are not affected, so that a better image can be obtained.

Further, as shown in FIG. 7, for example, by applying a voltage having the same polarity as the charging polarity of the toner 14 to the blade 30 (elastic member 32) by the voltage application device 28, the toner 14 adheres to the blade 30. May be prevented.

[Brief description of drawings]

FIG. 1 is an illustrative view showing one embodiment of the present invention.

FIG. 2 is an illustrative view showing a blade used in the embodiment in FIG.

FIG. 3 is an illustrative view showing an action of a blade used in the embodiment in FIG.

FIG. 4 is an illustrative view showing a modified example of a blade.

FIG. 5 is an illustrative view showing a modified example of a blade.

FIG. 6 is an illustrative view showing a modified example of a blade.

FIG. 7 is an illustrative view showing another embodiment of the present invention.

FIG. 8 is an illustrative view showing a conventional technique.

FIG. 9 is an illustrative view showing a state in which toner adheres to a tip portion of a blade in a conventional technique.

[Explanation of symbols]

 10 ... Developing device 12 ... Photosensitive drum 14 ... Toner 16 ... Housing 24 ... Developing roller 26 ... Supply roller 30 ... Blade 32 ... Elastic member 34 ... Film member 35 ... Bonding material

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Asahiro Katayama 2-5-5 Keihan Hondori, Moriguchi City, Osaka Sanyo Electric Co., Ltd.

Claims (2)

[Claims] 1. A developer tank for developing an electrostatic latent image formed on a surface of a photoconductor with a one-component developer, the developing tank containing the one-component developer therein, In a developing device including a developer carrying member that supplies the one-component developer to a photoconductor, and a blade that regulates the thickness of the one-component developer attached to the developer carrying member, the blade has a free end. The plate-shaped elastic member and the one-component developer that are partially laminated and fixed to the elastic member so as to project forward from the free end, and have a friction coefficient with the one-component developer. And a film member having a coefficient of friction larger than that of the developer, wherein the elastic member presses the film member against the developer carrying member. 2. The developing device according to claim 1, wherein the film member is pressed against the developing roller by directly pressing the film member at the free end of the elastic member without inclusions.