Color image forming apparatus having means for properly superimposing image colors on each other
First Claim
1. An image forming apparatus comprising:
- scanner means, using a plurality of laser beams having the same characteristic, for scanning a predetermined color image, each of the laser beams representing the predetermined color image and being shifted with respect to each other in a vertical scanning direction by a first pitch, the first pitch being defined by dividing a diameter of each of the laser beams by the number of the laser beams;
an optical recording system including a rotating polygon mirror which deflects each of the laser beams;
a body system including a rotating photosensitive body onto which each laser beam deflected by the rotating polygon mirror is radiated so as to form a latent image corresponding to the predetermined color image; and
selecting means for selecting one of the laser beams of the scanner means based on a time difference between a position detecting signal and a position signal, the position detecting signal indicating that each laser beam is ready to be radiated onto the photosensitive body of the body system, the position signal indicating that the photosensitive body is located at a position where each laser beam can be properly radiated thereon, and the position detecting signal being asynchronous with the position signal.
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Abstract
An image forming apparatus using a plurality of laser beams having the same characteristic in order to form a predetermined color image. The predetermined color image consists of a plurality of image colors. The laser beams are shifted with respect to each other in a vertical scanning direction by a diameter of each laser beam divided by the number of the laser beams. Since a rotating of a polygon mirror which deflects the laser beams is asynchronous with a rotating of a photosensitive body on which each laser beam is radiated so as to form a latent image, image colors are shifted with respect to each other. According to the present invention, one of the laser beams is selected for each image color, based on a timing difference between the polygon mirror and the photosensitive body, so that image colors can be superimposed on each other.
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Citations
8 Claims
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1. An image forming apparatus comprising:
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scanner means, using a plurality of laser beams having the same characteristic, for scanning a predetermined color image, each of the laser beams representing the predetermined color image and being shifted with respect to each other in a vertical scanning direction by a first pitch, the first pitch being defined by dividing a diameter of each of the laser beams by the number of the laser beams; an optical recording system including a rotating polygon mirror which deflects each of the laser beams; a body system including a rotating photosensitive body onto which each laser beam deflected by the rotating polygon mirror is radiated so as to form a latent image corresponding to the predetermined color image; and selecting means for selecting one of the laser beams of the scanner means based on a time difference between a position detecting signal and a position signal, the position detecting signal indicating that each laser beam is ready to be radiated onto the photosensitive body of the body system, the position signal indicating that the photosensitive body is located at a position where each laser beam can be properly radiated thereon, and the position detecting signal being asynchronous with the position signal. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An image forming apparatus comprising:
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scanner means for scanning each line of a predetermined color image and for generating an image data representing the predetermined color image by means of a laser beam, the predetermined color image comprising a plurality of image colors; an optical recording system including a rotating polygon mirror which deflects the laser beam; a body system including a rotating photosensitive body onto which the laser beam deflected by the rotating polygon mirror is radiated so as to form a latent image corresponding to the predetermined color image; buffer means for storing at least three lines of the image data, a first line of image data being stored twice; and switch means, coupled to the body system, for determining, based on a time difference between a position detecting signal and a position signal, whether or not the first line of image data is output twice to the body system, and for outputting each line of image data to said body system so that the image colors can be approximately superimposed on each other, the position detecting signal indicating that the laser beam is ready to be radiated onto the photosensitive body of the body system, the position signal indicating that the photosensitive body is located at a position where the laser beam can be properly radiated thereon, and the position detecting signal being asynchronous with the position signal.
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Specification