Electrophotography – Cleaning of imaging surface – Blade
Reexamination Certificate
2002-07-25
2004-03-02
Grainger, Quana M. (Department: 2852)
Electrophotography
Cleaning of imaging surface
Blade
C399S351000
Reexamination Certificate
active
06701123
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a cleaning device carried on, for example, an image forming apparatus of an electrophotographic system and to an image forming apparatus.
Presently, in an image forming apparatus of an electrophotographic system, for example, there is commonly used an image forming apparatus equipped with a latent image carrier composed of an organic photoreceptor containing organic photoconductive substances. The reason for this is as follows; that is, an organic photoreceptor has many advantageous points compared with other image carriers, including that materials coping with various exposure light sources covering a visible light through infrared radiation are easily developed, materials which cause no environmental pollution can be selected, and manufacturing cost is low.
In the image forming apparatus of this kind, there is known an image forming apparatus that is equipped, as a means to eliminate residual toner such as not-transferred toner or after-transfer-residual toner on an organic photoreceptor, with a cleaning device which is of a blade cleaning system to bring a flat cleaning blade made of an elastic object to be in contact with a surface of the organic photoreceptor and thereby to eliminate residual toner on the organic photoreceptor.
However, with regard to the organic photoreceptor, its mechanical strength is small, and thereby, deterioration or cracks on its surface are easily caused when making many prints, while, energy of contact with toner for visualizing an electrostatic latent image formed on the surface of the organic photoreceptor is great, and thereby, various problems described below are easily caused in the cleaning step to eliminate residual toner which has passed through a transfer area.
For example, because of the contact energy which is great, there are easily caused phenomena such as “blade eversion” which means that a tip edge of the cleaning blade that is in contact with a surface of the organic photoreceptor follows to move in the moving direction of the organic photoreceptor to be reversed, “blade bound” which means that the cleaning blade bounds on the surface of the organic photoreceptor, while being affected by the force acting in the direction to compress and deform the cleaning blade that is caused by movement of the organic photoreceptor, or “blade squeaking” which means that a minute vibration caused at a portion where the cleaning blade is in contact with the surface of the organic photoreceptor is resonant with the organic photoreceptor to produce high metallic sound.
On the other hand, in the image forming apparatus of an electrophotographic system, toner particles are now required to be small in size from the viewpoint of high image quality of an image, and a polymerization method such as, for example, an emulsion polymerization method or a suspension polymerization method is favorably used as a method to obtain the aforementioned toner particle.
However, adhesive power between toner particles and an organic photoreceptor becomes greater as toner particles are made to smaller, and thereby, removing of residual toner on the organic photoreceptor becomes more difficult, and when the so-called polymerization toner produced by the polymerization method is used, in particular, a form of a toner particle becomes to be closer to a spherical shape. Therefore, a toner particle rolls on the organic photoreceptor to cause easily a cleaning failure which means that the toner particle slips through the cleaning blade and is called the so-called “slipping-through”, which causes a problem that it is more difficult to remove residual toner on the organic photoreceptor. In particular, the surface of the organic photoreceptor tends to be worn out, and when toner sticks to the unevenness on the surface generated by wear, slipping-through of a few toner is generated for a long time, and these toner particles which have slipped through contaminate charging members (charging wires and charging rollers), resulting in a problem that forming of images having high image quality is difficult.
For preventing occurrence of such cleaning failure, TOKKAIHEI No. 3-189675, for example, discloses a cleaning system wherein mechanical cleaning by a cleaning blade and electrostatic cleaning are used together.
To be concrete, in the structure of the cleaning system, a brush roller made of conductive material is installed at the position which is upstream side of the cleaning blade in the direction of movement of a latent image carrier, and on this brush roller, there is impressed appropriate-sized bias voltage whose polarity is opposite to that of residual toner on the latent image carrier, for example, and thereby, the cleaning efficiency has been improved by both a mechanical cleaning effect by means of a cleaning blade and an electrostatic cleaning effect by means of the brush roller.
However, in the image forming apparatus of the aforementioned structure, the greater part of residual toner on the latent image carrier are removed by the brush roller located at the upstream side in the direction of movement of the latent image carrier, and thereby, an amount of residual toner arriving at the cleaning blade is extremely small in many cases, thus, aforementioned blade eversion and blade squeaking tend to be caused, resulting in a problem that stable forming of images having high image quality for a long time is difficult.
Further, to prevent occurrence of cleaning failure like that stated above, it has been suggested to make the particle shape of toner to be used to be amorphous, for example, to make a form of a particle of toner to be a shape of an ellipse, or to make a surface shape of a particle of toner to be of an unevenness shape, but none of them has been a solution in the actual conditions.
The invention has been achieved based on the aforementioned circumstances, and its object is to provide a cleaning device which is provided with a cleaning blade and is capable of exhibiting high cleaning power stably for a long time.
Another object of the invention is to provide an image forming apparatus which is capable of removing surely residual toner on a latent image carrier and thereby is capable of forming stably images having high image quality for a long time.
SUMMARY OF THE INVENTION
The cleaning device of the invention is provided with a cleaning blade mechanism that comprises a cleaning blade arranged so that its tip edge may touch the surface of a cylindrical latent image carrier that is driven to rotate and a supporting member that is positioned on the outer surface of a base end portion of the cleaning blade to urge the cleaning blade to be in contact with the surface of the latent image carrier, and in the cleaning blade mechanism, there is provided a flexible and laminar vibration-damping member which is held at its base end portion by the supporting member to extend in the same direction as that of the cleaning blade, and on the tip end portion of the vibration-damping member, there are formed slit-shaped slits so that a plurality of tab portions may be formed in the axial direction of the latent image carrier, and a tip edge of the tab portion is positioned at the outer surface of the cleaning blade.
On the cleaning device of the invention, it is preferable that a ratio of the protruded length of the vibration-damping member extending beyond the tip edge of the supporting member to that of the cleaning blade extending beyond the tip edge of the supporting member is greater than 0.1 and is not more than 0.9.
On the cleaning device of the invention, it is preferable that a length of the tab portion of the vibration-damping member in the direction of the axis of the latent image carrier is within a range of 1/100-1/10 of the length of the cleaning blade in the axial direction, and it is further preferable that a depth of a slit formed on the tip end portion is in the size ranging from 1/10 to 1/1 of the protruded length of the vibration-damping member.
The image forming apparatus of the invention is characteri
Endo Isao
Fukuo Chohiko
Makino Toru
Matsudaira Sachie
Mochizuki Fumitaka
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