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US 7,460,159 B2Granted
Image forming apparatus
AssigneeRicoh Company, Ltd.
InventorsHisakazu Ohkawara, Hidenori Akamatsu
Life of this patent
Estimating the term…
Abstract
Magnification correction of an image is performed by changing the cycle time of an optional pixel in the unit of pixel, until a phase adjustment amount (phase shift value) calculated by fixing the frequency exceeds a preset specified value, and after the phase adjustment amount exceeds the preset specified value, magnification correction of the image is performed by changing the frequency of an image signal in the unit of a line or in the unit of a plurality of lines. Accordingly, the number of execution of the magnification correction of an image by the latter method, in which it is necessary to suspend the image forming operation at the time of execution thereof, can be reduced.
Claims38
An image forming apparatus comprising:
- a deflector that deflects optical beams modulated according to an image signal to perform scanning in a horizontal scanning direction to form an image on an image carrier;
- two optical beam detectors that respectively detect optical beams deflected by the deflector at two positions on a horizontal scanning line;
- a time difference measuring unit that measures the time difference between detection of the optical beams by the detectors;
- a magnification correcting unit that corrects the magnification of an image in the horizontal scanning direction based on the time difference measured by the time difference measuring unit, wherein the magnification correcting unit includes
- a frequency modulator that performs magnification correction of an image by changing a frequency of the image signal in units of a line or lines;
- and
- a phase modulator that performs magnification correction of the image by fixing the frequency and changing a cycle time of an optional pixel in units of pixel;
- a comparing unit that compares the phase adjustment amount calculated by the phase modulator with a preset specified value;
- and
- an arrangement that causes the phase modulator to perform the magnification correction of the image upon the comparing unit determining that the phase adjustment amount does not exceed the specified value, and, once the comparing unit determines that the phase adjustment amount exceeds the specified value, causes the frequency modulator to perform the magnification correction of the image.
7 more elements
An image forming apparatus comprising:
- a deflector that deflects optical beams modulated according to an image signal to perform scanning in a horizontal scanning direction to form an image on an image carrier;
- two optical beam detectors that respectively detect optical beams deflected by the deflector at two positions on a horizontal scanning line;
- a time difference measuring unit that measures the time difference between detection of the optical beams by the detectors;
- a magnification correcting unit that corrects the magnification of an image in the horizontal scanning direction based on the time difference measured by the time difference measuring unit, wherein the magnification correcting unit includes
- a frequency modulator that performs magnification correction of an image by changing a frequency of the image signal in units of line or lines;
- and
- a phase modulator that performs magnification correction of the image by changing a cycle time of an optional pixel in units of pixel;
- a comparing unit that compares a phase adjustment amount in a predetermined region in the horizontal scanning direction calculated by the phase modulator with a preset specified value;
- and
- an arrangement that, depending on the result obtained by the comparing unit, decides whether the phase modulator performs the magnification correction of the image or the frequency modulator performs the magnification correction of the image.
7 more elements
An image forming apparatus comprising:
- a deflector that deflects optical beams modulated according to an image signal to perform scanning in a horizontal scanning direction to form an image on an image carrier;
- two optical beam detectors that respectively detect optical beams deflected by the deflector at two positions on a horizontal scanning line;
- a time difference measuring unit that measures the time difference between detection of the optical beams by the detectors;
- a magnification correcting unit that corrects the magnification of an image in the horizontal scanning direction based on the time difference measured by the time difference measuring unit, wherein the magnification correcting unit includes
- a frequency modulator that performs magnification correction of an image by changing a frequency of the image signal in units of line or lines;
- and
- a phase modulator that performs magnification correction of the image by changing a cycle time of an optional pixel in units of pixel;
- a comparing unit that compares the phase adjustment amount in a predetermined region in the horizontal scanning direction calculated by the phase modulator with a preset specified value;
- a predetermined region-changing unit that changes the predetermined region in the horizontal scanning direction corresponding to an image area in the horizontal scanning direction;
- and
- an arrangement that, depending on the result obtained by the comparing unit, decides whether the phase modulator performs the magnification correction of the image or the frequency modulator performs the magnification correction of the image.
8 more elements
An image forming apparatus comprising:
- a deflector that deflects optical beams modulated according to an image signal to perform scanning in a horizontal scanning direction to form an image on an image carrier;
- two optical beam detectors that respectively detect optical beams deflected by the deflector at two positions on a horizontal scanning line;
- a time difference measuring unit that measures the time difference between detection of the optical beams by the detectors;
- a magnification correcting unit that corrects the magnification of an image in the horizontal scanning direction based on the time difference measured by the time difference measuring unit, wherein the magnification correcting unit includes
- a frequency modulator that performs magnification correction of an image by changing a frequency of the image signal in units of line or lines;
- and
- a phase modulator that performs magnification correction of the image by changing a cycle time of an optional pixel in units of pixel;
- a comparing unit that compares the phase adjustment amount in a predetermined region in the horizontal scanning direction calculated by the phase modulator with a preset specified value;
- a predetermined region-changing unit that changes the predetermined region in the horizontal scanning direction depending on a size, a shape, or an orientation of a transfer paper;
- and
- an arrangement that, depending on the result obtained by the comparing unit, decides whether the phase modulator performs the magnification correction of the image or the frequency modulator performs the magnification correction of the image.
8 more elements
An image forming apparatus comprising:
- a deflector that deflects optical beams modulated according to an image signal to perform scanning in a horizontal scanning direction to form an image on an image carrier;
- two optical beam detectors that respectively detect optical beams deflected by the deflector at two positions on a horizontal scanning line;
- a time difference measuring unit that measures the time difference between detection of the optical beams by the detectors;
- a magnification correcting unit that corrects the magnification of an image in the horizontal scanning direction based on the time difference measured by the time difference measuring unit, wherein the magnification correcting unit includes
- a frequency modulator that performs magnification correction of an image by changing a frequency of the image signal in units of line or lines;
- and
- a phase modulator that performs magnification correction of the image by fixing the frequency and changing a cycle time of an optional pixel in the unit of pixel;
- a comparing unit that compares the phase adjustment amount calculated by the phase modulator with a preset specified value;
- a specified value-changing unit that changes the specified value according to an image type;
- and
- an arrangement that causes the phase modulator to perform the magnification correction of the image until the comparing unit determines that the phase adjustment amount exceeds the specified value, and, once the comparing unit determines that the phase adjustment amount exceeds the specified value, causes the frequency modulator to perform the magnification correction of the image.
8 more elements
An image forming apparatus comprising:
- a deflector that deflects optical beams modulated according to an image signal to perform scanning in a horizontal scanning direction to form an image on an image carrier;
- two optical beam detectors that respectively detect optical beams deflected by the deflector at two positions on a horizontal scanning line;
- a time difference measuring unit that measures the time difference between detection of the optical beams by the detectors;
- a magnification correcting unit that corrects the magnification of an image in the horizontal scanning direction based on the time difference measured by the time difference measuring unit, wherein the magnification correcting unit includes
- a frequency modulator that performs magnification correction of an image by changing a frequency of the image signal in units of a line or lines;
- and
- a phase modulator that performs magnification correction of the image by fixing the frequency and changing a cycle time of an optional pixel in units of pixel;
- a comparing unit that compares the phase adjustment amount in a horizontal scanning predetermined region calculated by the phase modulator with a preset specified value;
- a specified value-changing unit that changes the specified value according to an image type;
- and
- an arrangement that, depending on the result obtained by the comparing unit, decides whether the phase modulator performs the magnification correction of the image or the frequency modulator performs the magnification correction of the image.
8 more elements
An image forming apparatus comprising:
- a deflector that deflects optical beams modulated according to an image signal to perform scanning in a horizontal scanning direction to form an image on an image carrier;
- two optical beam detectors that respectively detect optical beams deflected by the deflector at two positions on a horizontal scanning line;
- a time difference measuring unit that measures the time difference between detection of the optical beams by the detectors;
- a magnification correcting unit that corrects the magnification of an image in the horizontal scanning direction based on the time difference measured by the time difference measuring unit, wherein the magnification correcting unit includes
- a frequency modulator that performs magnification correction of an image by changing a frequency of the image signal in units of a line or lines;
- and
- a phase modulator that performs magnification correction of the image by fixing the frequency and changing a cycle time of an optional pixel in units of pixel;
- and
- a frequency adjustment amount converter that converts the phase adjustment amount set by the phase modulator to a frequency adjustment amount by the frequency modulator.
6 more elements
An image forming apparatus comprising:
- a deflector that deflects optical beams modulated according to an image signal to perform scanning in a horizontal scanning direction to form an image on an image carrier;
- two optical beam detectors that respectively detect optical beams deflected by the deflector at two positions on a horizontal scanning line;
- a time difference measuring unit that measures the time difference between detection of the optical beams by the detectors;
- a magnification correcting unit that corrects the magnification of an image in the horizontal scanning direction based on the time difference measured by the time difference measuring unit, wherein the magnification correcting unit includes
- a frequency modulator that performs magnification correction of an image by changing a frequency of the image signal in units of a line or lines;
- and
- a phase modulator that performs magnification correction of the image by fixing the frequency and changing a cycle time of an optional pixel in units of pixel;
- a frequency adjustment amount converter that converts the phase adjustment amount set by the phase modulator to a frequency adjustment amount by the frequency modulator;
- a comparing unit that compares the phase adjustment amount in a horizontal scanning predetermined region with a preset specified value;
- a region-changing unit that changes the horizontal scanning predetermined region according to a horizontal scanning imaging range;
- and
- an arrangement that causes the phase modulator to perform the magnification correction of the image upon the comparing unit determining that the phase adjustment amount does not exceed the specified value, and, once the comparing unit determines that the phase adjustment amount exceeds the specified value, causes the frequency modulator to perform the magnification correction of the image based on the frequency adjustment amount calculated by the frequency adjustment amount converter.
9 more elements
An image forming apparatus comprising:
- a deflector that deflects optical beams modulated according to an image signal to perform scanning in a horizontal scanning direction to form an image on an image carrier;
- two optical beam detectors that respectively detect optical beams deflected by the deflector at two positions on a horizontal scanning line;
- a time difference measuring unit that measures the time difference between detection of the optical beams by the detectors;
- a magnification correcting unit that corrects the magnification of an image in the horizontal scanning direction based on the time difference measured by the time difference measuring unit, wherein the magnification correcting unit includes
- a frequency modulator that performs magnification correction of an image by changing a frequency of the image signal in units of a line or lines;
- and
- a phase modulator that performs magnification correction of the image by fixing the frequency and changing a cycle time of an optional pixel in units of pixel;
- a frequency adjustment amount converter that converts the phase adjustment amount set by the phase modulator to a frequency adjustment amount by the frequency modulator;
- a comparing unit that compares the phase adjustment amount in a horizontal scanning predetermined region exceeds a preset specified value;
- a region-changing unit that changes the horizontal scanning predetermined region according to a size, a shape, or an orientation of a transfer paper;
- and
- an arrangement that causes the phase modulator to perform the magnification correction of the image upon the comparing unit determining that the phase adjustment amount does not exceed the specified value, and, once the comparing unit determines that the phase adjustment amount exceeds the specified value, causes the frequency modulator to perform the magnification correction of the image based on the frequency adjustment amount calculated by the frequency adjustment amount converter.
9 more elements
Dependencies are inferred from the claim text.