Electrophotography – Internal machine environment – Particle or contaminant control
Reexamination Certificate
2000-06-06
2001-10-23
Lee, Susan S.Y. (Department: 2852)
Electrophotography
Internal machine environment
Particle or contaminant control
C399S092000, C399S093000
Reexamination Certificate
active
06308024
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a dust protector for preventing particles such as toner and dust from sticking to an image exposure device such as ROS (raster output scanner) and LED array used in an image forming apparatus such as a printer and copying machine utilizing an electrophotographic system, and the image forming apparatus utilizing the same. More particularly, the invention relates to a dust protector suitable for an image exposure device for performing image exposure on a member to be exposed from below and an image forming apparatus utilizing the same.
2. Description of the Related Art
Conventional image forming apparatuses of this type such as printers and copying machines utilizing an electrophotographic system have a configuration in which image exposure is performed by an image exposure device such as an ROS or LED array on a surface of a photosensitive drum to form an electrostatic latent image thereon in accordance with image information and in which the electrostatic latent image is developed and transferred to and fused on transfer paper to form a monochrome or full color image on the same.
As image forming apparatuses for such printers, copying machines and the like, a variety of so-called tandem type color image forming apparatuses have been proposed in which plural image forming units for forming images in predetermined colors on a photosensitive drum are provided in parallel with each other to allow high speed formation of a full color image and in which the images in different colors formed by the plurality of image forming units are directly transferred to transfer ipaper transported by a transfer material transport belt on a multiplex basis or are temporarily transferred to an intermediate transfer belt on a multiplex basis and are thereafter subjected to a secondary transfer from the intermediate transfer belt to transfer paper at a time. Such apparatuses have already been released as products by the present applicant.
The so-called tandem type full color image forming apparatuses as described above have a configuration in which image forming units for colors such as yellow (Y), magenta (M), cyan (C) and black (K) are provided in parallel with each other; image exposure is performed on a surface of a photosensitive drum of each of the image forming, units by an image exposure device such as an ROS or LED array provided above the photosensitive drums to form latent images in accordance with image information; and the latent images are developed and transferred to and fused on transfer paper to form a full color image.
Tandem type full color image forming apparatuses as described above have a problem that the apparatuses become massive because four image forming units for colors such as yellow (Y), magenta (MH, cyan (C) and black (K) are provided in parallel with each other and a transfer material transport belt and an intermediate transfer belt for transferring images from those four image forming units must be provided under the same and because a transport material must be provided under those belts to transport transfer paper removed from the transfer material transfer belt and/or to transport transfer paper on which images have been transferred from the intermediate transfer belt.
Techniques have already been proposed to allow tandem type full color image forming apparatuses as described above to be made compact including, for example, those disclosed in Japanese unexamined patent publications No. H5-61307/1993, No. H7-140747/1995, No. H8-95333/1996, No. H10-307439/1998, etc.
A color image forming apparatus according to Japanese unexamined patent publication No. H5-61307 is a color image forming apparatus having an image forming body in the form of a stretched belt and plural developers provided under the same in which a cleaning portion is disposed adjacent to the developers and in which the image forming bodies and the developers are configured such that they can be integrally attached to and detached from the image forming apparatus.
A color image forming apparatus according to Japanese unexamined patent publication No. H7-140474 is equipped with four processing units having at least a photosensitive body and a developer for forming images in four different colors, two optical beam generating units, a polarizing unit having at least a set of polarizing mirrors and a set of lenses and a splitting unit for splitting two optical beams from the two optical beam generating units and for guiding the split four optical beams to the four respective photosensitive bodies. The apparatus is configured such that each of the processing units sequentially forms an image in one respective color.
A color image forming apparatus according to Japanese unexamined patent publication No. H8-95333 is an image forming apparatus wherein three or more image forming units are arranged each of which is formed by arranging rows of light-emitting elements in the form of an array on an inner circumference of a photosensitive drum formed by sequentially stacking a translucent conductive layer and a photoconductive layer on a translucent support body in the axial direction of the drum. The image forming unit at one end is configured as a monochrome image forming mechanism which uses a black toner in a developing portion thereof, and developing portions and transfer portions of the remaining image forming units are respectively provided under and above the photosensitive drums thereof. The image forming units are connected with a transfer belt. An image forming mechanism for monochrome or color images is provided by using a black toner in the developing portion of the image forming unit adjacent to the monochrome image forming mechanism and color toners in the developing portions of the remaining image forming units. The image forming apparatus is configured with a detecting unit for detecting each of sheets of paper supplied from a cassette sequentially, a switching unit for transporting the sheets of paper sequentially supplied from the cassette to the monochrome image forming mechanism or the monochrome/color image forming mechanism alternately according to a detection signal from the detecting unit and a fusing unit for sequentially fusing sheets of paper on which image transfer has been performed by the monochrome image forming mechanism or monochrome/color image forming mechanism alternately.
An image forming apparatus according to the Japanese unexamined patent publication No. H10-307439 is an image forming apparatus having a writing unit for illuminating plural photosensitive bodies provided in association with respective component colors with illumination beams modulated based on image information in respective component colors to form electrostatic latent images associated with the colors of the image information on the respective photosensitive bodies, a transport unit for transporting transfer paper on which images are to be formed from the image information, an image forming unit including the plural photosensitive bodies, disposed close to the transport unit in a face-to-face relationship therewith, for transferring the image information as images formed on the photosensitive bodies to the transfer paper and a fusing unit disposed at one end of the transport unit for performing a fusing process on the transfer paper on which the image information has been transferred. The writing unit is disposed under the image forming unit, and the transport unit, transfer unit and fusing unit are disposed to be able to rotate integrally with the image forming unit such that they define a sufficient operating space with the image forming unit.
However, in the case of the image forming apparatuses disclosed in the Japanese unexamined patent publications No. H5-61307, No. H7-140747 and No. H8-95333, although the tandem type full color image forming apparatuses can be made compact, the image exposure devices such as the writing unit of those image forming apparatuses must be provided under the respective image forming units
Egusa Naoyuki
Hisano Tohru
Ichikawa Yoshihiko
Ishikawa Tomonori
Nakayama Yutaka
Fuji 'Xerox Co., Ltd.
Lee Susan S.Y.
Oliff & Berridg,e PLC
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