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.
Claims21
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 a first 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 said 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 in said first non-writing period, 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 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 said first non-writing period in the detecting, 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 during a first 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 said 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 in said first non-writing period, said second non-writing period being different from said first non-writing period.
Dependencies are inferred from the claim text.