Image forming apparatus, and method of correcting timing for generating laser beams
AssigneeRicoh Company, Ltd.
InventorsYoshinobu Takeyama, Nobuyuki Yanagawa
Life of this patent
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Abstract
A printer includes laser beam detecting sensors for detecting a laser beams at two positions in the main scanning direction. Write clock generating circuits measure a number of counts of a predetermined clock during a period since one of the laser beam detecting sensors detects each of the beams until another sensor detects the beam. A write clock frequency adjusting circuit takes the number of counts for one laser beam as a reference value and adjusts write clock frequencies of other laser beams so as to coincide with the reference value.
Claims12
An image forming apparatus, comprising:
- a plurality of optical systems and a plurality of image carriers, each optical system scanning a surface of a corresponding image carrier with a laser beam in a main scanning direction to form an image of a specific color on the image carrier;
- a plurality of first detecting units and a plurality of second detecting units, each first detecting unit being situated at a first position along the main scanning direction of a corresponding laser beam and each second detecting unit situated at a second position along the main scanning direction of the corresponding laser beam, wherein the first detecting unit and the second detecting unit detect the corresponding laser beam;
- and
- a clock frequency adjusting unit that, counts number of clocks of a write clock during a period since a desired one of the first detecting units detects the corresponding laser beam until a desired one of the second detecting unit detects the corresponding laser beam, selects a count of the number of clocks for one laser beam as a reference value, and adjusts a write clock frequency of each of the laser beams other than the one lased beam so as to coincide with the reference value.
A method of correcting timing for generating laser beams in an image forming apparatus, the image forming apparatus having a plurality of optical systems and a plurality of image carriers, each optical system scanning a surface of a corresponding image carrier with a laser beam in a main scanning direction to form an image of a specific color on the image carrier, the method comprising:
- detecting the laser beams at least at a first position and a second position, wherein the first position and the second position being on the main scanning direction of each laser beam;
- counting number of clocks of a write clock during a period since the laser beam is detected at a desired one of the first position until the laser beam is detected at a desired one of the second position;
- selecting a count of the number of clocks for one laser beam, out of the counts of the number of clocks for the laser beams, as a reference value;
- and
- adjusting a write clock frequency of each of the laser beams other than the one lased beam so as to coincide with the reference value.
Dependencies are inferred from the claim text.