Photocopying – Projection printing and copying cameras – Multicolor picture
Reexamination Certificate
2000-07-24
2001-09-25
Adams, Russell (Department: 2851)
Photocopying
Projection printing and copying cameras
Multicolor picture
C355S041000, C355S045000, C355S047000, C250S234000, C250S235000, C347S101000, C347S187000, C347S215000, C347S225000, C347S231000, C399S032000, C399S051000, C399S078000
Reexamination Certificate
active
06295116
ABSTRACT:
CLAIM OF PRIORITY
This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. §119 from an application entitled Image Printing Apparatus earlier filed in the Korean Industrial Property Office on Jul. 29, 1999, and there duly assigned Ser. No. 99-31056 by that Office.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to optical scanning systems for printers, and more particularly, to an optical scanning system for a printer that suppresses image print errors on a photosensitive belt due to variations in the amount of light repeatedly scanned by the photosensitive belt from an optical scanning unit.
2. Description of the Related Art
A printer may reproduce images or text on a photosensitive medium such as a photosensitive (or photoreceptor) belt to which toner is applied. Where a light beam strikes the photosensitive belt, it will hold developer for transfer to a sheet of paper.
An image is formed on the photosensitive belt by scanning the beam of light onto the photosensitive belt. Multiple rollers circulate the photosensitive belt, while a development unit develops the image to be printed on a transfer surface of the photosensitive belt. The developed image on the photosensitive belt is transferred to the paper or other printable medium when it passes the transfer unit.
For a high quality image to be printed, the positioning of the image on the photosensitive belt is important. One problem that occurs is that the image print starting position is irregularly set along the edge of the photosensitive belt in the traveling direction.
Exemplar of the background art U.S. Pat. No. 6,072,176 for Laser Beam Optical Scanning Device and Image Forming Apparatus with Laser Beam Optical Scanning Device issued to Kohsaka et al., U.S. Pat. No. 6,043,484 for Printer Optical Scanning Apparatus and Color Printer Optical Scanning System issued to Park, U.S. Pat. No. 5,138,479 for Light Beam Scanning Apparatus and Method of Detecting a Variation of a Scanning Speed of a Light Beam issued to Ando, U.S. Pat. No. 5,606,449 for Optical Scanning Device issued to Nishiyama, U.S. Pat. No. 5,365,364 for Optical Scanner and Printer issued to Taylor, U.S. Pat. No. 5,255,063 for Color Copying Apparatus with Improved Start Timing of a Scanner issued to Ideyama et al. disclose optical scanning systems for printers. I have found that the art does not show a way to reduce the irregularity of the starting position of the image print on a photosensitive medium of a printer.
SUMMARY OF THE INVENTION
To solve the above problems, it is an objective of the present invention to provide an optical scanning system for a printer, in which an image print error due to variations in an amount of light repeatedly scanning a photosensitive belt after being emitted from an optical scanning unit can be suppressed.
It is another object to have a higher quality of printing though a more accurate optical scanning system for a printer.
It is yet another object to have a scanning system for a printer that reduces errors in the starting position of the image print placed on a photosensitive medium of the printer.
It is still yet another object to have a printer that has the same image print starting position in each line scanned onto a photosensitive medium of the printer.
To achieve the objective of the present invention, there is provided an optical scanning system for a printer having an optical scanning unit having a deflector divided into a plurality of deflection regions to allow repetitive scanning of light emitted from a light source by rotation, the optical scanning unit for scanning light onto a photosensitive belt traveling around a plurality of rollers; a first photodetector installed at a position separated from the edge of the photosensitive belt, to be able to receivable light scanned beyond the edge of the photosensitive belt; a second photodetector installed a predetermined distance apart from the first photodetector, to be able to receive light scanned just beyond the edge of the photosensitive belt until the light hits the edge of the photosensitive belt; a scanning reference position signal generator for generating a scanning reference position signal at a point in time at which a signal output from the first photodetector in response to the reception of light, and a signal output from the second photodetector in response to the reception of light have the same level; an edge pulse generator for generating an edge pulse signal whose width corresponds to the period from the reception of the scanning reference position signal until the light reception of the second photodetector is terminated; and a controller for calculating the degree of deviation from a reference track of the photosensitive belt, in a direction perpendicular to the traveling direction of the photosensitive belt, using the width of the edge pulse signal, and controlling the driving of the optical scanning unit such that light corresponding to image information is emitted onto the photosensitive belt, beginning from the starting point of an image print region of the photosensitive belt.
Preferably, the optical scanning system further has a belt steering portion for controlling one of the rollers for use in steering the photosensitive belt, to allow the traveling of the photosensitive belt along the reference track, where the controller calculates the amount of deviation from the reference track of the photosensitive belt, using the width of the edge pulse signal, and controls the belt steering portion to reduce the amount of deviation.
Preferably, the first and second photodetectors are separated from each other to the extent that both the first and second photodetectors share a light spot emitted from the optical scanning unit at the middle point between the first and second photodetectors.
REFERENCES:
patent: 5138479 (1992-08-01), Ando
patent: 5255063 (1993-10-01), Ideyama et al.
patent: 5365364 (1994-11-01), Taylor
patent: 5392060 (1995-02-01), Imakawa
patent: 5606449 (1997-02-01), Nishiyama
patent: 5724087 (1998-03-01), Sugano et al.
patent: 5926203 (1999-07-01), Shimura et al.
patent: 5987193 (1999-11-01), Eguchi et al.
patent: 6043484 (2000-03-01), Park
patent: 6072176 (2000-06-01), Kohsaka et al.
Adams Russell
Brown Khaled
Bushnell , Esq. Robert E.
Samsung Electronics Co,. Ltd.
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