Printing apparatus, resolution conversion printing method for printing apparatus, and storage medium storing computer-readable program

• US 6,332,666 B1
• Filed: 05/30/2000
• Issued: 12/25/2001
• Est. Priority Date: 05/28/1999
• Status: Active Grant

• Current Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Original Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Inventors: Ikeda, Sanae
• Primary Examiner(s): Le, N.
• Assistant Examiner(s): Nguyen, Lamson D.
• Application Number:
  US09/580,955
• Time in Patent Office: 574 Days
• Field of Search: 347/40, 347/5, 347/12, 347/225, 347/238, 347/237, 347/112, 347/116, 358/1.5, 358/1.7, 358/1.9, 358/1.16, 358/1.18, 358/1.2, 358/1.13
• US Class Current: 347/40
• CPC Class Codes: G06K 15/1223 Resolution control, enlarging or reducing, edge or detail enhancement
• CPC Class Codes: G06K 15/128 generating or processing printable items, e.g. characters

Abstract

In a laser beam printer, it is thought that the number of scanning lines for the unit length in a sheet carrying direction (a resolution of a sub scanning direction) can be changed by making processing speed in the sheet carrying direction changeable. Further, in a general printer, raster data is generated based on vector data or code data from a superior apparatus (expansion). Ordinarily, in the printer, the raster data corresponding to resolution of a printing unit is generated by the expansion, and the generated raster data is output to the printing unit. In a printing apparatus which has the above printing unit capable of changing at least a resolution of a predetermined direction, even when the printing unit prints the data from the superior apparatus with a resolution 1/N times (N is an integer of two or more) a predetermined resolution for the predetermined direction, the printing data is expanded into the raster data with the predetermined resolution, and the resolution of the predetermined direction of the raster data is converted by generating the pixel value of one pixel, on the basis of pixel values of N pixels aligned with the predetermined direction of the obtained raster data.

Claims

1. A printing apparatus which has a printing unit capable of performing printing in a main scanning direction and in a sub scanning direction perpendicular to the main scanning direction respectively with different resolutions, comprising:

storage means for storing raster data expanded into binary data of first and second pixel values with a predetermined resolution;

first setting means for setting a multiple-speed number of printing speed to said printing unit, the multiple-speed number representing what times standard printing speed the printing is to be performed at;

second setting means for setting the printing resolution of the main scanning direction to be the resolution of the raster data stored in said storage means, and setting the printing resolution of the sub scanning direction to be a quotient of the resolution of the raster data divided by the multiple-speed number of the printing speed, to said printing unit; and

resolution conversion output means for outputting a video signal to said printing unit, the video signal being obtained by integrating to one pixel an area aligned with the sub scanning direction of the raster data stored in said storage means and composed of pixels of the number as much as the multiple-speed number of the printing speed.

2. An apparatus according to claim 1, wherein said resolution conversion output means determines a value of the one pixel obtained by integrating the area, on the basis of the number of pixels of the first pixel value or the number of pixels of the second pixel value existing within the area.

3. An apparatus according to claim 2, wherein, when the number of pixels of the first pixel value is the same as the number of pixels of the second pixel value existing within the area, said resolution conversion output means determines the value of the one pixel obtained by integrating the area, on the basis of distribution position of the pixels having the first pixel value or distribution position of the pixels having the second pixel value existing within the area.

4. A resolution conversion printing method for a printing apparatus having a printing unit capable of performing printing in a main scanning direction and in a sub scanning direction perpendicular to the main scanning direction respectively with different resolutions, said method comprising:

an expansion step of expanding printing information into raster data of a predetermined resolution, on a memory;

a first setting step of setting a multiple-speed number of printing speed to the printing unit, the multiple-speed number representing what times standard printing speed the printing is to be performed at;

a second setting step of setting the printing resolution of the main scanning direction to be the resolution of the raster data expanded on the memory, and setting the printing resolution of the sub scanning direction to be a quotient of the resolution of the raster data divided by the multiple-speed number of the printing speed, to the printing unit; and

a resolution conversion output step of outputting a video signal to the printing unit, the video signal being obtained by integrating to one pixel an area aligned with the sub scanning direction of the raster data expanded on the memory and composed of pixels of the number as much as the multiple-speed number of the printing speed.

5. A storage medium which stores a computer-readable program to control a printing apparatus having a printing unit capable of performing printing in a main scanning direction and in a sub scanning direction perpendicular to the main scanning direction respectively with different resolutions, said program comprising:

an expansion step of expanding printing information into raster data of a predetermined resolution, on a memory;

a first setting step of setting a multiple-speed number of printing speed to the printing unit, the multiple-speed number representing what times standard printing speed the printing is to be performed at;

a second setting step of setting the printing resolution of the main scanning direction to be the resolution of the raster data expanded on the memory, and setting the printing resolution of the sub scanning direction to be a quotient of the resolution of the raster data divided by the multiple-speed number of the printing speed, to the printing unit; and

a resolution conversion output step of outputting a video signal to the printing unit, the video signal being obtained by integrating to one pixel an area aligned with the sub scanning direction of the raster data expanded on the memory and composed of pixels of the number as much as the multiple-speed number of the printing speed.

6. A printing apparatus which has a printing unit capable of performing printing with resolutions of main and sub scanning directions differentiated by changing printing speed, comprising:

expansion means for expanding printing data from a superior apparatus into raster data with a predetermined resolution;

storage means for storing the expanded raster data;

raster data conversion means for generating, when said printing unit performs the printing at speed N times (N is an integer of two or more) printing speed corresponding to the predetermined resolution, the raster data obtained by integrating to one pixel an area composed of N pixels, on the basis of the raster data of N pixels aligned with the sub scanning direction of the raster data stored in said storage means; and

output means for outputting the raster data converted by said raster data conversion means to said printing unit.

7. An apparatus according to claim 6, wherein said raster data conversion means determines a pixel value of the raster data obtained by integrating the N-pixel area to the one pixel, on the basis of the number of pixels of a predetermined pixel value among the N pixels.

8. An apparatus according to claim 7, wherein said raster data conversion means determines the pixel value of the raster data obtained by integrating the N-pixel area to the one pixel, on the basis of the number of pixels of the predetermined pixel value among the N pixels and distribution position of the pixels of the predetermined pixel value within the area.

9. An apparatus according to claim 6, wherein said raster data conversion means determines a pixel value of the raster data obtained by integrating the N-pixel area to the one pixel, on the basis of the sum of the pixel values of the N pixels.

10. An apparatus according to claim 6, wherein said raster data conversion means determines a pixel value of the raster data obtained by integrating the N-pixel area to the one pixel, on the basis of the number of pixels of a predetermined pixel value among the N pixels and a pixel value of the pixel corresponding to an area adjacent to the N-pixel area.

11. A printing apparatus which has a printing unit capable of changing at least a resolution of a predetermined direction, comprising:

expansion means for expanding, even when said printing unit performs the printing for the predetermined direction with a resolution 1/N times (N is an integer of two or more) a predetermined resolution printing data from a superior apparatus into raster data with the predetermined resolution;

storage means for storing the expanded raster data;

raster data conversion means for converting, when said printing unit performs the printing for the predetermined direction with the resolution 1/N times the predetermined resolution, the resolution of the raster data for the predetermined direction by generating a pixel value of one pixel, on the basis of pixel values of N pixels aligned with the predetermined direction of the raster data stored in said storage means; and

output means for outputting the raster data converted by said raster data conversion means to said printing unit.

12. An apparatus according to claim 11, wherein said raster data conversion means determines the pixel value of the one pixel to be generated, on the basis of the number of pixels of a predetermined pixel value among the N pixels.

13. An apparatus according to claim 12, wherein said raster data conversion means determines the pixel value of the one pixel to be generated, on the basis of the number of pixels of the predetermined pixel value among the N pixels and positions of the pixels of the predetermined pixel value.

14. An apparatus according to claim 11, wherein said raster data conversion means determines the pixel value of the one pixel to be generated, on the basis of the sum of the pixel values of the N pixels.

15. An apparatus according to claim 11, wherein said raster data conversion means determines the pixel value of the one pixel to be generated, on the basis of the number of pixels of a predetermined pixel value among the N pixels and a pixel value of the pixel adjacent to the N pixels.

16. An image processing method for a printing apparatus having a printing unit capable of changing at least a resolution of a predetermined direction, said method comprising:

an expansion step of expanding, even when the printing unit performs printing with a resolution 1/N times (N is an integer of two or more) a predetermined resolution, printing data from a superior apparatus into raster data with the predetermined resolution;

a storage step of storing the expanded raster data in a storage means;

a raster data conversion step of converting, when the printing unit performs the printing for a predetermined direction with the resolution 1/N times the predetermined resolution, the resolution of the raster data for the predetermined direction by generating a pixel value of one pixel, on the basis of pixel values of N pixels aligned with the predetermined direction of the raster data stored in the storage means; and

an output step of outputting the raster data converted in said raster data conversion step to the printing unit.

17. A method according to claim 16, wherein said raster data conversion step determines the pixel value of the one pixel to be generated, on the basis of the number of pixels of a predetermined pixel value among the N pixels.

18. A method according to claim 17, wherein said raster data conversion step determines the pixel value of the one pixel to be generated, on the basis of the number of pixels of the predetermined pixel value among the N pixels and positions of the pixels of the predetermined pixel value.

19. A method according to claim 16, wherein said raster data conversion step determines the pixel value of the one pixel to be generated, on the basis of the sum of the pixel values of the N pixels.

20. A method according to claim 16, wherein said raster data conversion step determines the pixel value of the one pixel to be generated, on the basis of the number of pixels of a predetermined pixel value among the N pixels and a pixel value of the pixel adjacent to the N pixels.