Incremental printing of symbolic information – Light or beam marking apparatus or processes – Scan of light
Reexamination Certificate
2001-11-16
2003-06-03
Pham, Hai (Department: 2861)
Incremental printing of symbolic information
Light or beam marking apparatus or processes
Scan of light
C347S255000
Reexamination Certificate
active
06573924
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention belongs to a technical field of image recording by scanning exposure. More specifically, the present invention relates to an exposure head of a low-cost and compact-sized type capable of realizing multi-channel image exposure, and to an image recording apparatus using the exposure head.
Exposure apparatuses, which perform scanning exposure for photosensitive materials such as silver halide photographic photosensitive materials and electrophotographic photoreceptors with recording light modulated in accordance with images to be recorded, are used in various kinds of printers and copiers.
With respect to such an exposure apparatus, the one has been primarily used, which uses so-called light beam scanning exposure in the following manner. Light beams modulated in accordance with an image to be recorded are deflected in a main scanning direction, and, at the same time, a photosensitive material and the light beams are moved relatively to each other in an auxiliary scanning direction perpendicular to the main scanning direction, whereby the photosensitive material is scan-exposed two-dimensionally by the light beams for image recording.
With the progress of technology in recent years, such a light beam scanning exposure has made it possible to record high quality images at a high-speed. However, the image exposure by light beam scanning shows a limitation to a realization of higher speed image exposure and higher resolution. Particularly, regarding large images often used in a printing field or the like, it is considered to be difficult to record a high quality image at a higher speed by use of the image exposure by the light beam scanning.
As a method of solving the foregoing problems and enabling a high-speed and high-quality image recording, multibeam image exposure has been known, in which a plurality of light beams simultaneously expose a photosensitive material.
As methods of realizing the multibeam exposure, the following methods have been known: a method using light sources such as laser diodes (LD) corresponding to light beams in the number, which perform an exposure; a method which splits a light beam into a plurality of light beams by use of an optical system and performs an exposure by use of a light modulator such as an acoustooptic modulator (AOM) for each of the light beams; and a method which allows light beams emitted from a light source to be incident into a spatial light modulator such as a liquid crystal shutter array by use of an optical system, and to be focused on an exposure surface as the plurality of light beams individually modulated in order to form an image.
However, in the method of using the light sources corresponding to the light beams in the number, though a sufficient amount (or intensity) of light can be obtained for each light beam, costs are required in various points, such as a plurality of light sources; an optical system for making the light beam emitted from each light source be incident into and focused on a predetermined position in order to form an image; and unitization thereof.
In the method of split the light beam, the number of split light beams, that is, the number of light beams available is limited in terms of an amount of light (or light intensity). Moreover, since the optical system is required for making the plurality of light beams incident into the light modulator, this method is also expensive.
In the method of using the spatial light modulator, since a transverse multimode light source such as a broad area LD is available, a sufficient amount (or intensity) of light can be obtained for each light beam. However, though the optical system and the like are required for making the light beams emitted from the light source incident into all modulation elements of the spatial light modulator, this method is also expensive.
In addition, any method described above cannot prevent the increase in size of the apparatus for obtaining multibeams (a plurality of light beams). The improvement is desired in this point.
SUMMARY OF THE INVENTION
The objects of the present invention are to solve the foregoing problems in the conventional art. Specifically, the first object of the present invention is to provide an exposure head of a multi-channel type capable of performing the multi-channel exposure with less limitations in terms of the amount (or intensity) of light by use of light beams of sufficient light amount (intensity) for all channels, and capable of realizing a cost and size reduction of the apparatus.
Further, the second object of the present invention is to provide an image recording apparatus using the above exposure head.
In order to attain the first object described above, the first aspect of the present invention provides an exposure head comprising: at least one light source of a broad area type; an optical waveguide gradually broadening in a broad area direction of the at least one light source toward a traveling direction of light emitted from the at least one light source; a member collimating the light traveling in a perpendicular direction to the broad area direction, the light being emitted from the optical waveguide; and a light modulating device including a plurality of modulation units arrayed in the broad area direction.
In order to attain the second object described above, the second aspect of the prevent invention provides an image recording apparatus, comprising: an exposure head including; at least one light source of a broad area type; an optical waveguide gradually broadening in a broad area direction of the at least one light source toward a traveling direction of light emitted from the at least one light source; a member collimating the light traveling in a perpendicular direction to the broad area direction, the light being emitted from the optical waveguide; and a light modulating device including a plurality of modulation units arrayed in the broad area direction; an optical system for focusing on a predetermined position the light emitted from the exposure head; and a scanner for allowing the exposure head and a photosensitive material to move relatively, while regulating the photosensitive material at the predetermined position.
Preferably, the optical waveguide has one of a tapered shape and a parabolic shape.
Preferably, each of the modulation units includes a transparent conductive material disposed so as to be opposite to a boundary surface of the optical waveguide with a space therebetween and a unit for bringing the conductive material into contact with the boundary surface of the optical waveguide by use of static electricity.
REFERENCES:
patent: 4713821 (1987-12-01), Bradford et al.
patent: 5228049 (1993-07-01), Paoli
patent: 10-50968 (1998-02-01), None
Miyagawa Ichiro
Sawano Mitsuru
Fuji Photo Film Co. , Ltd.
Pham Hai
Sughrue & Mion, PLLC
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