Incremental printing of symbolic information – Electric marking apparatus or processes – Electrostatic
Reexamination Certificate
1999-10-28
2001-06-19
Pendergrass, Joan (Department: 2852)
Incremental printing of symbolic information
Electric marking apparatus or processes
Electrostatic
C347S238000
Reexamination Certificate
active
06249296
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the arrangement of an exposure apparatus used in an electrophotographic image forming apparatus in which a latent image formed by exposing a photosensitive member is developed and transferred to a recording sheet, thereby recording the image.
2. Related Background Art
An image forming apparatus is widely used in practice, in which light emitted by a stationary light source such as an LED array is focused onto the surface of a photosensitive member by using a focusing optical fiber lens array to form a latent image on the surface of the photosensitive drum, and the latent image is visualized with a toner and then transferred onto a recording sheet, thus forming an image. When an LED array is used as an exposure light source, the apparatus can be downsized more than in a case using a laser as the light source.
Particularly, a color image forming apparatus, which has three or four LED arrays and forms a color image by overlaying images corresponding to respective colors obtained by color separation, can utilize the advantage of downsizing obtained by using the LED arrays.
When, however, a color image is formed by overlaying three or four colors, if an overlay error occurs, color misregistration or color irregularity is produced to greatly degrade the image quality. More specifically, in the conventional exposure apparatus, even if the LED arrays are fabricated straight in the initial state, as the apparatus is operated and the temperature in the apparatus increases, the straightness gradually degrades. This is due to the following reason. As the temperature in the apparatus increases, the temperature of an LED head having the LED arrays also increases, and the LED head is distorted due to a difference in thermal expansion of the various types of members.
In order to solve this problem, a fan is provided to cool the LED head, so that the distortion of the LED head is suppressed. In this case, the size of the apparatus, power consumption, and noise disadvantageously increase.
Furthermore, in the conventional LED head, a foreign substance such as the toner or dust may enter through the gap between the constituent elements to attach to the light-emitting portion or image forming means. In this case, light is partly shielded to cause a defect in the image.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention has to provide an exposure apparatus which can always maintain appropriate exposure even if heat is generated by the operation of the apparatus.
It is another object of the present invention to provide an exposure apparatus in which a foreign substance can be prevented from attaching to a light-emitting portion or image forming means, so an exposure defect will not occur.
To achieve the above objects, according to the present invention, there is provided an exposure apparatus comprising light-emitting means having a linear array of a plurality of light-emitting elements, a driver for driving the light-emitting elements, and image forming means for causing light emitted by the light-emitting elements to form an image at a predetermined position, wherein the light-emitting means and the driver are supported by a first support, the image forming means is supported by a second support, and a heat conductive member is interposed in a gap between the first and second supports.
To achieve the above objects, according to the present invention, there is also provided an exposure apparatus comprising light-emitting means having a linear array of a plurality of light-emitting elements, a driver for driving the light-emitting elements, and image forming means for causing light emitted by the light-emitting elements to form an image at a predetermined position, wherein the light-emitting means is supported by a first support, the driver and the image forming means are supported by a second support, and a heat conductive member is interposed in a gap between the first and second supports.
According to the present invention, the first and second supports are made of the same material.
According to the present invention, the heat conductive member is made of a resilient body.
According to the present invention, the image forming means is a focusing optical fiber lens array.
According to the present invention, the exposure apparatus is used in an electrophotographic image forming apparatus.
REFERENCES:
patent: 5036339 (1991-07-01), Hediger
patent: 5504516 (1996-04-01), Bax
patent: 5506612 (1996-04-01), Ogata et al.
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Pendergrass Joan
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