Multi-pass inkjet printer system and method of using same

• US 6,179,407 B1
• Filed: 11/20/1998
• Issued: 01/30/2001
• Est. Priority Date: 11/20/1998
• Status: Expired due to Term

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Company (HP Inc.)
• Inventors: Bockman, Francis E.
• Primary Examiner(s): NGUYEN, THINH H
• Application Number:
  US09/197,291
• Time in Patent Office: 802 Days
• Field of Search: 347/40, 347/15, 347/37, 347/41, 347/12, 347/19, 395/117, 395/109, 358/518, 358/298
• US Class Current: 347/40
• CPC Class Codes: B41J 2/2132 Print quality control characterised by dot disposition, e.g. for reducing white stripes or banding methods for local corrections by dot omission, image edge enhancement, or multi-pass mask selection G06K15/102; colour conversion H04N1/40
• CPC Class Codes: G06K 15/107 Mask selection
• CPC Class Codes: G06K 2215/0094 Colour printing

Abstract

An inkjet color printer accesses image data to be printed on a pixel by pixel basis and determines the Z number of drops of different color inks to distribute per pixel over a predetermined number of passes in a multi-pass print mode of operation. Predetermined constraints relative to the maximum number of drops of a single ink color per pixel and per pass permit maskless drop ordering and an even distribution of ink over time per pixel.

Claims

1. A masking method comprising the steps of:

determining a total number of droplets of each colorant ink in a plurality of different colorant inks to be deposited at a given pixel location;

determining once for said total number of droplets of each colorant ink to be deposited at said given pixel location in a substantially even rate ink droplet distribution for each colorant ink to be deposited over N number of passes available in an inkjet color printer; and

assigning an individual one of the N number of passes to each individual colorant ink droplet to be deposited at said given pixel location to effect said substantially even drop distribution at said given pixel location.

2. A masking method according to claim 1, further comprising the steps of:

receiving pixel data indicative of a desired number of ink droplets for another pixel in an image to be printed; and

repeating the steps of the first mentioned determining, the second mentioned determining, assigning, and receiving a sufficient number of times to form the desired pixels on a print medium.

3. A masking method according to claim 1, wherein said step of assigning includes randomly assigning the N number of passes to each individual colorant ink droplet to be deposited.

4. A masking method according to claim 1, further comprising the steps of:

determining pairs of different color inks when two droplets of different ink colorants are being deposited in any one of the N number of passes.

5. A masking method according to claim 1, further comprising the steps of:

determining during which ones of the N number of passes that no droplets of ink will be deposited.

6. A masking method according to claim 1, wherein the plurality of different colorant inks is three different colorant inks.

7. A masking method according to claim 1, wherein the plurality of different colorant inks is six different colorant inks.

8. A masking method comprising the steps of:

determining a total number of droplets of each colorant ink in the plurality of different colorant inks to be deposited at a given pixel location;

determining once for said total number of droplets of each colorant ink to be deposited at said given pixel location in a substantially even rate ink droplet distribution for each colorant ink to be deposited over N number of passes available in an inkjet color printer;

assigning an individual one of the N number of passes to each individual colorant ink droplet to be deposited at said given pixel location to effect said substantially even drop distribution at said given pixel location;

limiting the number of droplets of colorant ink to be deposited at said given pixel location to a maximum number of droplets; and

limiting the maximum number of droplets of any one ink colorant in any one of the N number of passes to X number of droplets, where X equal the first mentioned maximum number of droplets to be deposited at said given pixel location divided by the N number of passes.

9. A masking method according to claim 8, wherein X is equal to 1 droplet of ink when N is equal to 8 passes.

10. A masking method according to claim 9, wherein X is equal to 2 droplets of ink when N is equal to 4 passes.

11. A masking method according to claim 10, wherein the first mentioned step of limiting includes;

determining a type of print medium for depositing the ink droplets.

12. A masking method comprising the steps of:

receiving pixel data indicative of a desired number of ink droplets per color per pixel in an image to be printed;

determining an ink droplet distribution pattern for said desired number of ink droplets over N number of ink droplet depositing opportunities;

said distribution pattern limiting the maximum number of droplets of any one ink color to at least one droplet of ink in each of the N number of ink droplet depositing opportunities; and

assigning each ink droplet of the determined distribution to an individual one of the N number of depositing opportunities.

13. A masking method according to claim 12, wherein said distribution pattern is an even distribution pattern so that the maximum number of ink droplets per color per pixel is limited to a fixed number Y of droplets over the N number of depositing opportunities.

14. A masking method according to claim 12, wherein said distribution pattern further limits the maximum number of ink droplets per pixel to 8 drops.

15. A masking method according to claim 14, wherein when N is equal to 8, Y is equal to 1.

16. A masking method according to claim 15, wherein the total maximum number of ink droplets per pixel per depositing opportunity is 2.

17. A masking method according to claim 12, wherein said distribution pattern further limits the maximum number of ink droplets per pixel to 4 drops.

18. A masking method according to claim 12, wherein when N is equal to 4, Y is equal to 2.

19. A masking method according to claim 18, wherein the total maximum number of ink droplets per pixel per depositing opportunity is 1.

20. A masking method according to claim 12, wherein said step of assigning is a random assignment to any one of the N number of depositing opportunities.

21. A masking method according to claim 12, wherein said step of assigning includes:

providing a random number generator to generate non repeating patterns to use in selecting individual ones of the N number of depositing opportunities.

22. A masking method according to claim 12, further comprising the steps of:

providing Z number of different color inks.

23. A masking method according to claim 22, further comprising the steps of:

determining pairs of different color inks when two droplets of different color ink are being deposited in any one of the N number of depositing opportunities.

24. A masking method according to claim 12, further comprising the steps of:

determining during which ones of the N number of depositing opportunities that no droplets of ink will be deposited.

25. A multi-pass masking system, comprising:

an ink drop control arrangement for receiving pixel data indicative of a desired number of ink droplets per color per pixel in an image to be printed;

said ink drop control arrangement being responsive to the pixel data for determining an ink droplet distribution pattern for said desired number of ink droplets over N number of ink droplet depositing opportunities;

said distribution pattern limiting the maximum number of droplets of any one ink color in any individual one of the N number of depositing opportunities to X number of droplets, where X equals the total number of droplets of any one ink color divided by the N number of depositing opportunities; and

a plurality of sequenced pseudo-random number generators responsive to said control arrangement for assigning randomly each set of X number of droplets of any one ink color to individual ones of the N number of depositing opportunities.

26. An inkjet color printer, comprising:

means for determining a total number of droplets of each colorant ink in a plurality of different colorant inks to be deposited at a given pixel location;

means for determining once for said total number of droplets of each colorant ink to be deposited at said given pixel location in a substantially even rate ink droplet distribution for each colorant ink to be deposited over N number of available passes available; and

means for assigning an individual one of the N number of passes to each individual colorant ink droplet to be deposited at said given pixel location to effect said substantially even drop distribution at said given pixel location.