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US 2003/0076554 A1Published application
Image scanning apparatus
AssigneeToshiba Tec Kabushiki Kaisha
InventorNaoaki Ide
Life of this patent
Estimating the term…
Abstract
With the present invention, by changing the scanning timing of a CCD line sensor in accordance with the amount of scanning misregistration corresponding to a magnification, misregistration of less than one line can be accurately corrected, thereby eliminating degradation of MTF, which has occurred in conventional apparatuses.
Claims11
A document scanning apparatus comprising:
- a scanning section which reads and scans a document line by line in the horizontal scanning direction thereof, with a relative movement of the document in the vertical scanning direction;
- a shift mechanism which shifts said scanning section and said document relative to each other in the vertical scanning direction of said document, at various speeds based on the scanning magnification;
- a CCD line sensor for the color red, to which an image for each line is guided from said scanning section, to convert it into pixel signals of a plurality of pixels based on the density of the red color component;
- a CCD line sensor for the color green provided parallel with said CCD line sensor for the color red with a predetermined distance therebetween, to which an image for each line is guided from said scanning section, to convert it into pixel signals of a plurality of pixels based on the density of the green color component;
- a CCD line sensor for the color blue provided parallel with said CCD line sensor for the color green with a predetermined distance therebetween, to which an image for each line is guided from said scanning section, to convert it into pixel signals of a plurality of pixels based on the density of the blue color component;
- a memory section which stores beforehand alienation time comprising a line unit component and a pixel unit component between said respective CCD line sensors, in such a state that said scanning section and said document are relatively shifted by said shift mechanism, at a different speed based on various scanning magnifications;
- a modification section which, at the time of scanning at a predetermined scanning magnification, reads the alienation time between said respective CCD line sensors based on this magnification, and modifies the output timing of the pixel signal from said each CCD line sensor, based on the pixel unit component of this readout alienation time;
- and
- a delay section which delays the pixel signal in a unit of one line, obtained by changing the output timing of the pixel signal from each said CCD line sensor by the modification section, by the line unit component of said alienation time.
6 more elements
An image forming apparatus comprising:
- a setting section which sets a scanning magnification at the time of forming an image;
- a scanning section which reads and scans a document line by line in the horizontal scanning direction, with a relative movement of the document in the vertical scanning direction;
- a shift mechanism which shifts said scanning section and said document relative to each other in the vertical scanning direction of said document, at various speeds based on the scanning magnification set by said setting section;
- a CCD line sensor for the color red, to which an image for each line is guided from said scanning section, to convert it into pixel signals of a plurality of pixels based on the density of the red color component;
- a CCD line sensor for the color green provided parallel with said CCD line sensor for the color red with a predetermined distance therebetween, to which an image for each line is guided from said scanning section, to convert it into pixel signals of a plurality of pixels based on the density of the green color component;
- a CCD line sensor for the color blue provided parallel with said CCD line sensor for the color green with a predetermined distance therebetween, to which an image for each line is guided from said scanning section, to convert it into pixel signals of a plurality of pixels based on the density of the blue color component;
- a memory section which stores beforehand alienation time comprising a line unit component and a pixel unit component between said respective CCD line sensors, in such a state that said scanning section and said document are relatively shifted at a different speed based on various scanning magnifications;
- a modification section which, at the time of scanning at a predetermined scanning magnification, reads the alienation time between said respective CCD line sensors based on this magnification, and modifies the output timing of the pixel signal from said each CCD line sensor, based on the pixel unit component of this readout alienation time;
- a delay section which delays the pixel signal in a unit of one line, obtained by changing the output timing of the pixel signal from said each CCD line sensor by the modification section, by the line unit component of said alienation time;
- and
- an image forming section which forms an image on an image forming medium, based on the pixel signal in a unit of one line for each color output from said delay section.
8 more elements
A document scanning method in an apparatus comprising:
- a scanning section which reads and scans a document line by line in the horizontal scanning direction thereof, with a relative movement of the document in the vertical scanning direction;
- a shift mechanism which shifts said scanning section and said document relative to each other in the vertical scanning direction of said document, at various speeds based on the scanning magnification;
- a CCD line sensor for the color red, to which an image for each line is guided from said scanning section, to convert it into pixel signals of a plurality of pixels based on the density of the red color component;
- a CCD line sensor for the color green provided parallel with said CCD line sensor for the color red with a predetermined distance therebetween, to which an image for each line is guided from said scanning section, to convert it into pixel signals of a plurality of pixels based on the density of the green color component;
- a CCD line sensor for the color blue provided parallel with said CCD line sensor for the color green with a predetermined distance therebetween, to which an image for each line is guided from said scanning section, to convert it into pixel signals of a plurality of pixels based on the density of the blue color component;
- and
- a memory section which stores beforehand alienation time comprising a line unit component and a pixel unit component between said respective CCD line sensors, in such a state that said scanning section and said document are relatively shifted by said shift mechanism, at a different speed based on various scanning magnifications;
- wherein said method comprises:
- modification of reading, at the time of scanning at a predetermined scanning magnification, the alienation time between said respective CCD line sensors based on this magnification and modifies the output timing of the pixel signal from said each CCD line sensor, based on the pixel unit component of this readout alienation time;
- and
- delaying the pixel signal in a unit of one line, obtained by changing the output timing of the pixel signal from said each CCD line sensor by said modification step, by the line unit component of said alienation time.
8 more elements
Dependencies are inferred from the claim text.