Cleaning device, and image forming method and image forming...

Electrophotography – Cleaning of imaging surface – Blade

Reexamination Certificate

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Reexamination Certificate

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06580897

ABSTRACT:

FIELD OF THE INVENTION
The invention relates to a cleaning device to be used in a electrophotographic copy machine or a printer, and an image forming method and an image forming apparatus using the cleaning device.
BACKGROUND OF THE INVENTION
Recently, an organic photoreceptor, hereinafter referred to a photoreceptor, containing an organic photoconductive substance is most widely used as an image carrier to be used in an electrophotographic image forming apparatus. The organic photoreceptor has advantages over another photoreceptor in that the organic photoreceptor responding various light sources from visible rays through infrared rays can be easily developed, a material without environment pollution can be selected and the material can be produced with a low cost. However, the organic photoreceptor has a shortcoming that such the photoreceptor is weak in the mechanical strength and tens to occur a degradation or formation of damage on the photoreceptor surface when the photoreceptor is subjected to many times of copying or printing operations.
Moreover, a remaining toner remained on the photoreceptor after transfer of the toner image to an image receiving member is difficultly removed since the contact energy of the photoreceptor with the toner for developing the electrostatic latent image formed on the photoreceptor is large. Consequently, various problems tend to be raised on the cleaning of the photoreceptor surface.
Besides, in the electrophotographic image forming method, a digital method is become the main current of the image formation technology accompanied with the progress in the digital technology. It is standardized in the digital image formation that a fine dot image of one pixel such as 400 dots per inch (dpi) is made actual image. Accordingly, a high quality image forming technology is required by which such the fine dot image can be reproduced with a high fidelity.
On the other hand, various methods for raising the mechanical strength of the photoreceptor surface have been proposed as a countermeasure against the degradation of the organic photoreceptor surface accompanied with the cleaning.
Japanese Patent Publication Open to Public Inspection No. 9-258460 proposes a photoreceptor having a surface layer of polycarbonate resin having a high hardness for reducing the surface abrasion. Such the photoreceptor having the polycarbonate resin layer is different from the usual photoreceptor in that the friction force between a cleaning blade, hereinafter simply referred to a blade and the surface of photoreceptor, since the surface abrasion of the photoreceptor by the cleaning is small. Consequently, an incompletely cleaning tends to be occurred by the turning over of the blade and the toner slipping through the blade caused by vibration of the blade.
Another one of the methods is technology regarding the production of toner. Currently, a crushed toner is mainly used to form an electrophotographic image, which is produced by mixing and kneading binder resin and pigment, and crushing the kneaded mixture to prepare a toner powder and classifying the crushed powder. However, there is a limit on the unifying of the size of such the toner particles, and the uniformities of the size and the shape of the toner particles are insufficient. It is difficult to achieve a sufficient high quality of image by an electrophotography using such the crushed toner.
Recently, an electrophotographic developer or an image forming method using a polymerized toner is proposed as a means to unify the size and the shape of the toner particles. The polymerized toner is produced by dispersing a raw material toner in an aqueous medium and polymerizing the dispersed monomer, thus a toner can be obtained composed of particles unformed in the size and the shape thereof.
However, a technical problem is newly raised when the polymerized toner is used in an image forming apparatus having the organic photoreceptor. The polymerized toner is produced so that the particles each have an approximately spherical shape since the shape of the toner is formed in the course of the polymerization of the toner. As well-known, the spherical toner remaining on the photoreceptor tends to cause incomplete cleaning. Particularly, the surface of the organic photoreceptor is easily abraded and slipping of the fine toner particle through the blade in a degree so as to form no image are occurred during a long period of time when the toner is adhered in the irregularities of the surface formed by the abrasion. The toner particles slipped through the blade contaminate a charging member such as a charging wire and a charging roller and an unevenness of the image is formed in the halftone image.
Various methods have been proposed for improving the incompletion of cleaning such as the turning over of the blade and the toner slipping through the blade in the image forming method using the polymerized toner. Among them, a proposal to change the shape of the toner particle from the spherical shape to an ellipse shape and that to make irregular the surface of the toner particle are tried. However, these proposals cannot be sufficient solving means.
SUMMARY OF THE INVENTION
The object of the invention is to solve the foregoing problems and to provide a cleaning device, and an image forming method and an image forming apparatus using the cleaning device, by which the cleaning effect is maintained for a long period of time and a good electrophotographic image can be obtained without any fault in image.
It is found by the inventors that a good cleaning property can be maintained and a stable vibration of the blade can be kept by sticking a plastic member to the cleaning blade, and the foregoing problems can be solved.
The invention and the embodiment thereof are described below.
1. A cleaning device removing residual toner on a photoreceptor wherein the cleaning device comprises a cleaning blade composed of a plurality of plate materials laminated each other, the plurality of plate materials including a cleaning blade member and a plastic member each of which is mounted on a support member, the cleaning blade member being brought into contact with said photoconductor and the plastic member not being brought into contact with said photoconductor, wherein elastic modulus of the cleaning blade D
1
and the elastic modulus of the plastic member D
2
satisfy
16≦
D
2
/D
1
≦2,800.
2. The cleaning device of item 1 wherein tensile strength H of the plastic member satisfies
1.4≦H≦35 (H: kgf/mm
2
).
3. The cleaning device of item 1 wherein bending strength M of the plastic member satisfies
0≦M≦41 (M: kgf/mm
2
).
4. The cleaning device of item 1 wherein length L
1
of the cleaning blade member is longer than length L
2
of the plastic member.
5. The cleaning device of item 1 wherein the cleaaning member and the plastic member are laminated with an adhesive layer.
6. The cleaning device of item 1, wherein the cleaning device satisfies;
0.1≦
L
2
/L
1≦0.9
wherein L
1
is a free length of the cleaning blade member and L2 is a free length of the plastic member,
{fraction (1/50)}
<t
2
/t
2
<1
wherein t
1
is a thickness of the cleaning blade member and t
2
is a thickness of the plastic member, and
1.4≦H≦35 (H: kgf/mm
2
).
wherein H is tensile strength of the plastic member.
7. The cleaning device of item 1, wherein the cleaning device satisfies;
0.1
<L
2
/L
1≦0.9
wherein L1 is a free length of the cleaning blade member and L2 is a free length of the plastic member,
{fraction (1/50)}<
t
2
/t
1
<1
wherein t
1
is a thickness of the cleaning blade member and t
2
is a thickness of the plastic member, and
0<M≦41 (M: kgf/mm
2
)
wherein bending M is bending strength of the plastic member.
8. The cleaning device of item 6 wherein L2/L1 is 0.3 to 0.7.
9. A cleaning device removing residual toner on a photoreceptor wherein the cleaning apparatus comprises a cleaning blade composed of a plurality of plate material laminated each other, the plurality of plate material including a cleaning blade membe

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