IMAGE FORMING APPARATUS AND METHOD THEREOF

• US 20080112012A1
• Filed: 10/25/2007
• Published: 05/15/2008
• Est. Priority Date: 11/13/2006
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Kurosawa, Hidenori, Morita, Seijiro, Ogura, Keigo, Yokoyama, Noboru
• Granted Patent: US 7,859,720 B2
• Time in Patent Office: Days
• US Class Current: 358/3.03
• CPC Class Codes: H04N 1/0473 in subscanning direction, e.g. picture start or line-to-line synchronisation
• CPC Class Codes: H04N 1/506 Reproducing the colour component signals picture-sequentially, e.g. with reproducing heads spaced apart from one another in the subscanning direction
• CPC Class Codes: H04N 2201/04787 by changing or controlling the addresses or values of pixels, e.g. in an array, in a memory, by interpolation

Abstract

In a line by line image forming apparatus, line switching information which depends on scan line curve and an overlap data length to be read that overlaps across a plurality of lines before and after a switching position instructed by line switching information are set in a register. If switching to the line above or below is instructed by the line switching information, an address generating unit, when reading image data from an image memory, generates the read address and read data length of the image memory in accordance with the line switching information and the overlap data length, and reads image data corresponding to a current line and the line above or below the current line in accordance with the generated data.

Claims

1. An image forming apparatus for forming an image, comprising:

a storage unit configured to store at least a plurality of lines of image data;

a data reading unit configured to read image data in a line direction from said storage unit based on a read start address;

a setting unit configured to set line switching address in the line direction, for switching a line of the image data to be read by said data reading unit from a first line to a second line;

a generating unit configured to generate the read start address of the second line in a case where said data reading unit switches the line of the image data from the first line to the second line, so that the read address of the first line in the line direction overlaps the read address of the second line in the line direction;

a control unit configured to control said data reading unit to read image data of the second line based on the read start address generated by said generating unit in a case where the read address, in the line direction, and to read the image data of the first line become identical to the line switching address;

a halftone processing unit configured to perform halftone processing based on the image data of the first line and the image data of the second line read by said data reading unit; and

an image forming unit configured to form an image based on the image data to which the halftone processing is performed by said halftone processing unit.

2. An image forming apparatus according to claim 1, wherein the second line is adjacent to the first line.

3. An image forming apparatus according to claim 2, wherein said setting unit sets the line switching address based on a length of each segment in a case where image data of one line is divided into a plurality of segments.

4. An image forming apparatus according to claim 3, wherein the length of each of the plurality of segments is variable.

5. An image forming apparatus according to claim 3, wherein the read start address equates to a base address of a segment to be read.

6. An image forming apparatus according to claim 1, wherein said data reading unit reads image data from the storage unit via a ring buffer.

7. An image forming method for forming an image, comprising:

a data reading step of reading image data in a line direction from a memory storing at least a plurality of lines of image data based on a read start address;

a setting step of setting line switching address in the line direction, for switching a line of the image data to be read in said data reading step from a first line to a second line;

an generating step of generating the read start address of the second line in a case where said data reading step switches the line of the image data from the first line to the second line, so that the read address of the first line in the line direction overlaps the read address of the second line in the line direction;

a controlling step of controlling said data reading step to read image data of the second line based on the read start address generated in said generating step in a case where the read address, in the line direction, and reading the image data of the first line become identical to the line switching address;

a halftone processing step of performing halftone processing based on the image data of the first line and the image data of the second line read in said data reading step; and

an image forming step of forming an image based on the image data to which the halftone processing is performed in said halftone processing step.

8. An image forming method according to claim 7, wherein the second line is adjacent to the first line.

9. An image forming method according to claim 7, wherein said setting step sets the line switching address based on a length of each segment in a case where image data of one line is divided into a plurality of segments.

10. An image forming method according to claim 9, wherein the length of each of the plurality of segments is variable.

11. An image forming method according to claim 9, wherein the read start address equates to a base address of a segment to be read.

12. An image forming method according to claim 7, wherein in said data reading step, image data is read from the memory via a ring buffer.

13. An image forming apparatus comprising:

an input unit configured to receive image data in pages;

an image data storage unit configured to store image data received by said input unit;

a reading unit configured to read image data stored in the image data storage unit based on a read start address and a read data length, as data segments of the read data length;

an image forming unit configured to scan an image support body based on scan lines of image data constituted by a plurality of the data segments read by said reading unit, and form an image on the image support body in the scan lines;

a correction information storage unit configured to store correction information for correcting curvature of the scan lines on the image support body;

a generating unit configured to generate a plurality of the read start addresses, based on the correction information stored in said correction information storage unit,

wherein said reading unit sequentially reads the plurality of data segments from the image data storage unit, while switching the plurality of read start addresses generated by the generating unit.

14. An image forming apparatus according to claim 13, wherein said image forming unit has a plurality of the image support bodies,

said correction information storage unit stores plural pieces of correction information corresponding one-to-one with the plurality of image support bodies, and

said generating unit generates the plurality of read start addresses, based on the correction information corresponding to each of a plurality of colors of the image data stored in said image data storage unit.

15. An image forming apparatus according to claim 14, wherein said reading unit performs DMA transfers of the data segments from said image data storage unit to the image forming unit, based on the read data length and the plurality of read start addresses generated by said generating unit.