Electrophotography – Image formation – Development
Reexamination Certificate
1998-06-30
2001-09-25
Braun, Fred L. (Department: 2852)
Electrophotography
Image formation
Development
Reexamination Certificate
active
06295429
ABSTRACT:
FIELD OF THE INVENTION AND RELATED ART
The present invention relates to an electrophotographic image forming apparatus.
In this specification, an electrophotographic image forming apparatus means an apparatus that forms an image on recording medium with the use of an electrophotographic image forming system. It includes, for example, an electrophotographic copying machine, an electrophotographic printer (laser beam printer, LED printer, and the like), a facsimile machine, a word processor, and the like.
A typical structure of a color laser beam printer prior to the present invention is as follows. A charging roller, to which voltage is being applied, is placed in contact with a photosensitive drum, with a predetermined contact pressure, to uniformly charge the peripheral surface of a photosensitive drum so that a latent image can be formed.
The charged peripheral surface of the photosensitive drum is exposed by a scanning section which comprises a laser diode. More specifically, the laser diode emits a laser beam modulated with image data signals toward a polygon mirror, which deflects the laser beam. The deflected laser beam is projected upon a polygon mirror, whereby the laser beam is caused to make a scanning movement in the direction of the generation of the photosensitive drum
1
while being focused upon the peripheral surface of the photosensitive drum
1
through an image forming lens and a deflection mirror; the scanning laser beam is projected upon the peripheral surface of the photosensitive drum
1
.
As a result, a plurality of electrostatic latent images correspondent to different primary color components of an original image, are formed on the peripheral surface of the photosensitive drum
1
by the laser beam modulated with the image data signals.
An image development rotary comprises a development unit for developing the latent image correspondent to magenta color, a development unit for developing the latent image correspondent to cyan color, a development unit for developing the latent image correspondent to yellow color, and a development unit for developing the latent image correspondent to black color.
In a latent image developing operation, the latent image developing unit (hereinafter, development unit), which contains the color toner correspondent to the latent image to be developed, is stopped at a position (hereinafter, developing position) where the distance between the peripheral surface of the latent image developing roller (hereinafter, development roller) of the development unit, and the peripheral surface of the photosensitive drum
1
, becomes minimum, that is, microscopic.
As the development unit is moved to the developing position, the development roller is connected to a high voltage power source of the main assembly of the image forming apparatus, so that bias for developing a latent image (hereinafter, development bias) is applied to the development unit. At the same time, the development roller is engaged with a driving means linked with the driving power source on the main assembly side of the image forming apparatus.
As the development roller is rotatively driven while the development bias is applied to the development roller, the latent image on the photosensitive drum is developed into a toner image.
The development unit is in the form of a development cartridge which integrally comprises the development roller as a latent image developing member, and a toner storing portion. The development unit in the form of a cartridge makes it possible for a user to maintain the image forming apparatus without relying on service personnel, and therefore, the operability of the apparatus is greatly improved. Thus, the development unit in the form of a cartridge (hereinafter, development cartridge) is widely used as a development unit for the electrophotographic image forming apparatus.
SUMMARY OF THE INVENTION
The present invention is an invention made by further developing the conventional technologies.
The primary object of the present invention is to provide an electrophotographic image forming apparatus which can form a desirable image on recording medium.
Another object of the present invention is to provide an electrophotographic image forming apparatus which can loosen the powder toner used for developing an electrostatic latent image, before developing the latent image.
Another object of the present invention is to provide an electrophotographic image forming apparatus, the development unit driving motor of which does not need to generate as much torque as the torque which the apparatus prior to the present invention must generate, to rotatively drive the development unit.
Another object of the present invention is to provide an electrophotographic image forming apparatus in which an intermittent development rotary rotation sequence, in which an image developing rotary is rotated, and then, temporarily stopped, is repeated a plurality of times immediately after one or more image development units are replaced.
Another object of the present invention is to provide an electrophotographic image forming apparatus in which development units are fitted in an image development rotary, and which requires less initial torque for driving the development unit than the apparatus prior to the present invention.
These and other objects, features and advantages of the present invention will become more apparent upon a consideration of the following description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawings.
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Isobe Hironobu
Kobayashi Kazunori
Braun Fred L.
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
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