Image forming apparatus and method with improved capabilities of correcting image magnification error
AssigneeRicoh Company, Ltd.
InventorKatsuhiko Maeda
Life of this patent
Estimating the term…
Abstract
An image forming apparatus and method that detects a light beam deflected by a polygon mirror at least at two separate locations on the line in the horizontal scanning direction, measures the difference in time of passage between these locations, makes a comparison between the thus determined interval and a reference interval, and generates a proper amount of correction corresponding to the determined interval, such as either correction data adapted to change the frequency of a pixel clock, or further correction data to change the period of the pixel clock by pixels.
Claims71
An image forming apparatus, comprising:
- an image forming unit;
- a detection unit configured to detect an error of image magnification in a horizontal scanning direction during at least one non-writing period, the non-writing period being defined by a period of time from a finish of a current image writing to a start of a next image writing in the horizontal scanning direction;
- and
- a correcting unit configured to:
- instruct said detection unit to detect said error during a first non-writing period, and
- correct said error during a second non-writing period based on a result of said error obtained by said detection unit, said second non-writing period being different from said first non-writing period.
An image forming apparatus, comprising:
- an image forming unit;
- a detection unit configured to detect an error of image magnification in a horizontal scanning direction, said error being detected between at least two pages during a continuous image printing operation on a plurality of pages;
- and
- a correcting unit configured to:
- instruct said detection unit to detect said error between first and second pages of a first group, and
- correct said error on third and fourth pages of a second group based on a result of said error detected by said detection unit, said second group being different from said first group.
An image forming apparatus configured to form a color image by superposing at least first and second monochromatic images in first and second colors, respectively, said image forming apparatus comprising:
- at least first and second image forming units configured to form said at least first and second monochromatic images, respectively;
- a detection unit configured to detect an error of image magnification in a horizontal scanning direction for said at least first and second colors, said error being detected between two pages during a continuous image printing operation on a plurality of pages;
- and
- a correcting unit configured to:
- instruct said detection unit to detect said error between first and second pages of a first group, and
- correct said error on third and fourth pages of a second group based on a result of said error detected by said detection unit, said second group being different from said first group.
A method for correcting an error of image magnification for an image forming apparatus, comprising:
- detecting an error of image magnification in a horizontal scanning direction during a first non-writing period, the non-writing period being defined by a period of time from a finish of image writing to a start of next image writing in the horizontal scanning direction;
- and
- correcting said error during a second non-writing period based on a result of said error obtained in the detecting, said second non-writing period being different from said first non-writing period.
A method for correcting an error of image magnification for an image forming apparatus, comprising:
- detecting an error of image magnification in a horizontal scanning direction between first and second pages of a first group during a continuous image printing operation on a plurality of pages;
- and
- correcting said error on third and fourth pages of a second group based on a result of said error obtained in the detecting, said second group being different from said first group.
A method for correcting an error of image magnification for an image forming apparatus configured to form a color image by superposing at least first and second monochromatic images in first and second colors, said at least first and second monochromatic images being formed by said at least a first and second image forming units, respectively, the method comprising:
- detecting an error of image magnification in a horizontal scanning direction between first and second pages of a first group for said at least first and second colors during a continuous image printing operation on a plurality of pages;
- and
- correcting said error on third and fourth pages of a second group based on a result of said error detected in the detecting, said second group being different from said first group.
An image forming apparatus, comprising:
- image forming means;
- detection means for detecting an error of image magnification in a horizontal scanning direction during at least one non-writing period, the non-writing period being defined by a period of time from a finish of a current image writing to a start of next image writing in the horizontal scanning direction;
- and
- correcting means for:
- instructing said detection means to detect said error during a first non-writing period, and
- correcting said error during a second non-writing period based on a result of said error obtained by said detection means, said second non-writing period being different from said first non-writing period.
An image forming apparatus, comprising:
- image forming means;
- detection means for detecting an error of image magnification in a horizontal scanning direction, said error being detected between at least two pages during a continuous image printing operation on a plurality of pages;
- and
- correcting means for:
- instructing said detection means to detect said error between first and second pages of a first group, and
- correcting said error on third and fourth pages of a second group based on a result of said error detected by said detection means, said second group being different from said first group.
An image forming apparatus configured to form a color image by superposing at least first and second monochromatic images in first and second colors, respectively, said image forming apparatus comprising:
- at least first and second image forming means configured to form said at least first and second monochromatic images, respectively;
- detection means for detecting an error of image magnification in a horizontal scanning direction for said at least first and second colors, said error being detected between two pages during a continuous image printing operation on a plurality of pages;
- and
- correcting means for:
- instructing said detection means to detect said error between first and second pages of a first group, and
- correcting said error on third and fourth pages of a second group based on a result of said error detected by said detection means, said second group being different from said first group.
Dependencies are inferred from the claim text.