Incremental printing of symbolic information – Light or beam marking apparatus or processes – Scan of light
Reexamination Certificate
1999-05-28
2003-06-24
Pham, Hai (Department: 2861)
Incremental printing of symbolic information
Light or beam marking apparatus or processes
Scan of light
C347S244000
Reexamination Certificate
active
06583805
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an exposure unit used in electrophotographic systems, such as copying machines and electrophotographic units, and relates to an electrophotographic image forming apparatus.
2. Description of the Related Art
Usual exposure systems for forming latent images on photosensitive members include laser beam systems and LED array systems. A laser beam system, however, requires optical components, such as polygon mirrors and lenses, and thus have some problems, for example, the difficulty of miniaturizing apparatuses and of operating at high-speed.
On the other hand, an LED array system uses an expensive substrate and requires the arrangement of many cut chips, because the array cannot be formed of one substrate. Such arrangement results in problematic steps and gaps between chips. Furthermore, the LED array system requires a rod lens array for forming an image on a photosensitive member. Since light is collected by the rod lens array with low efficiency, light from a luminescent device cannot be effectively used when diffused light is focused on the photosensitive member using the rod lens array. Thus, a high intensity of light must be emitted from the luminescent device so that the required intensity of light reaches the photosensitive member.
The present assignee disclosed, in Japanese Patent Application Laid Open No. 9-45477 and European Patent No. 0756334A2, a light emitting device including a positive electrode layer, an active layer, and a negative electrode layer in which the distance between the positive electrode layer and the negative electrode layer is partly different at some positions so as to emit mixed light having different wavelengths in response to the distance. In detail, the light emitting device includes a first substrate, a positive electrode layer formed on the first substrate, a second substrate, a negative electrode layer formed on the second substrate, and an active layer formed between the positive electrode layer and the negative electrode layer. Light emitting regions are formed between the positive electrode layer and the negative electrode layer in such a manner that the distance between the positive electrode layer and the negative electrode layer varies from one light-emitting region to another. The device further includes a resin layer disposed either between the first substrate and the positive electrode layer or between the second substrate and the negative electrode layer to form the light-emitting regions in which the distance varies.
In this light emitting device, the luminescent device is an organic luminescent device, and the substrate for forming the luminescent device has a microlens array. This pending patent, however, does not disclose an electrophotographic apparatus of the present invention.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an exposure unit for electrophotographic apparatuses, which can solve the above-mentioned problems.
It is another object of the present invention to provide an exposure unit for electrophotographic apparatuses, which is capable of high-speed operation, is compact, is formed with low cost, and has high resolution.
It is a further object of the present invention to provide an exposure unit for electrophotographic apparatuses, which can effectively use light emitted from a luminescent device.
It is another object of the present invention to provide an electrophotographic image forming apparatus using the exposure unit.
The exposure unit, for an image forming apparatus using an electrophotographic system in accordance with the present invention, includes a luminescent device array comprising a pair of electrodes and an organic compound layer disposed between the electrodes, and a microlens array arranged corresponding to the luminescent device array.
The electrophotographic image forming apparatus in accordance with the present invention includes an electrophotographic member, a charging unit, an exposure unit, a developing unit, a transfer unit, and a fixing unit, wherein the exposure unit includes a luminescent device array comprising a pair of electrodes and an organic compound layer disposed between the electrodes, and a microlens array arranged corresponding to the luminescent device array.
The exposure unit does not require alignment between the luminescent device array and a lens system. Such an exposure unit is applicable to an optical printer head and an electrophotographic apparatus.
REFERENCES:
patent: 4734723 (1988-03-01), Ishitobi
patent: 5023442 (1991-06-01), Taniguchi et al.
patent: 5465265 (1995-11-01), Ota
patent: 0 756 334 (1996-07-01), None
patent: 8-288064 (1996-11-01), None
patent: 9-45477 (1997-02-01), None
Serway, Raymond A., “Physics: For Scientists and Engineers”, Saunders College Publishing, pp. 764, 776 and 777, copyright 1982.
Koumura Noboru
Mashimo Seiji
Nagase Yukio
Senoo Akihiro
Ueno Kazunori
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Pham Hai
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