Systems and methods for object-optimized control of laser power

• US 6,239,829 B1
• Filed: 11/18/1998
• Issued: 05/29/2001
• Est. Priority Date: 11/18/1998
• Status: Expired due to Term

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Curry, Douglas N.
• Primary Examiner(s): Le, N.
• Assistant Examiner(s): NGUYEN, LAMSON D
• Application Number:
  US09/195,165
• Time in Patent Office: 923 Days
• Field of Search: 347/251, 347/240, 347/236, 347/246, 347/252, 347/5, 347/253, 395/109, 395/117, 358/456, 358/518, 382/173
• US Class Current: 347/251
• CPC Class Codes: H04N 1/40037 the reproducing element being a laser

Abstract

A method and apparatus for altering a drive signal provided to an image forming element of a printer based on the type of object being printed, e.g., text and/or lineart, halftone, etc., to provide an optimal exposure level for producing the particular object. The apparatus provides an increased drive signal which, for example, provides an increased laser power during text and/or lineart production using a high setpoint and re-normalizes laser power by providing a decreased drive signal which, for example, provides a decreased laser power during halftone production using a low setpoint. This increased power offers improved appearance of text and/or lineart and the re-normalization offers more quantization levels for tone adjustment, better highlight production, and better overall control of tone during halftone production in a write black printer.

Claims

1. A method for printing at least one image, each image having a plurality of portions of image data, the plurality of portions of each image having a plurality of different types of image data, the method comprising:

distinguishing, for each image, between the plurality of portions of image data that include different types of data within that image;

printing the portions of image data of that image that have of a first type of image data using a laser power drive signal at a first setpoint; and

printing the portions of image data of that image that have of a second type of image data using the laser power drive signal at a second setpoint,

wherein the first setpoint is different from the second setpoint and the first setpoint and second setpoint are set based on the type of data being printed.

2. The method of claim 1, wherein the first type of image data is halftone data and the second type of image data is text or lineart data.

3. The method of claim 1, wherein the first setpoint is lower than the second setpoint.

4. The method of claim 1, wherein the first and the second setpoints are set independently of each other.

5. A method for printing at least one image, each image having a plurality of portions of image data, the method comprising:

determining, for each image and each portion of image data whether that portion of image data of that image corresponds to a type of object; and

altering a setpoint of a drive signal used to render that portion of image data of that image based on whether that portion of image data of that image corresponds to the type of object.

6. The method of claim 5, wherein the drive signal affects a level of exposure light.

7. The method of claim 5, wherein the type of data is text or lineart data.

8. The method of claim 7, wherein the altering the setpoint step comprises one of increasing and decreasing the drive signal setpoint.

9. The method of claim 8, wherein increasing the drive signal setpoint increases a level of exposure provided by a light source in a printing apparatus.

10. A method for printing based on object optimized print data of an output image, the method comprising:

inputting document data defining a document, the document comprising at least one page;

converting the document data into a plurality of independent image objects, each independent image object having an object type indicated by at least a rendering tag, each page of the document comprising at least one of the plurality of independent image objects;

producing metabit data for each of the plurality of independent image objects based on the rendering tag indicating the type of object; and

modulating, based on the metabit data, a drive power supplied to an image forming element used to print at least one of the plurality of independent image objects.

11. The method for printing of claim 10, wherein modulating the drive power includes altering, based on the metabit data, the saturation laser power used to print at least one of the plurality of independent image objects.

12. A printer controller that adjusts a drive signal setpoint used to print a portion of image data of an image, that image having a plurality of portions of image data, the plurality of portions of that image having a plurality of different types of object, based on the type of object to which that portion of image data of that image corresponds, the printer controller comprising:

an image output terminal that receives print data and metabit data of that image, the image output terminal including an image processing system that contains an object-optimized image formation modulation subsystem that is selectively controlled by the metabit data sent to the image output terminal;

wherein;

the metabit data of each portion of image data of that image controls the object-optimized image formation modulation subsystem to select between different drive signal setpoints depending on the type of object to which that portion of image data of that image corresponds; and

the drive signal setpoint affects the formation of the object corresponding to that portion of image data of that image.

13. The printer controller of claim 12, wherein the drive signal setpoint controls the level of exposure light provided by a laser light or LED light source.

14. The printer controller of claim 12, wherein, when the portion of image data corresponds to a halftone object, the drive signal is set to a first setpoint and when the portion of image data corresponds to a text or lineart object, the drive signal is set to a second setpoint.

15. The printer controller of claim 14, wherein the first setpoint is independent of the second setpoint.

16. An image forming device, including the printer controller of claim 12.

17. The image forming device of claim 16 wherein the image forming device is a facsimile machine, a laser printer, an inkjet printer, a digital copier or a full-width-print bar printer.

18. A method for object-optimized printing based on characteristics of a bitmap region in which a portion of image data is located, the method comprising:

distinguishing between at least two of a first image region that includes only a text or lineart object, a second image region that includes only a halftone object and a third image region that includes both halftone and text or lineart objects;

altering a setpoint of a drive signal that drives an image forming device during printing of the image region based on the objects included within the image region.

19. The method of claim 18, wherein the altering step comprises:

driving the image forming device with a drive signal at a first setpoint during printing of the first image region;

driving the image forming device with a drive signal at a second setpoint during printing of an image region that includes only halftone objects; and

driving the image forming device with a drive signal at a third setpoint during printing of the third image region.

20. The method of claim 19, wherein the first, second and third setpoints are different from each other.

21. The method of claim 20, wherein the first setpoint is lower than the second setpoint and the third setpoint is between the first and second setpoints.