Mixed-density print masking in a mixed-swath-height printer

• US 6,017,113 A
• Filed: 11/05/1997
• Issued: 01/25/2000
• Est. Priority Date: 10/29/1993
• Status: Expired due to Term

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Company (HP Inc.)
• Inventors: Skene, John M., Bauman, Joseph H., Nicoloff, Nicholas Jr., Harris, Donald G., Azmoon, Majid
• Primary Examiner(s): Le, N.
• Assistant Examiner(s): Nguyen, Judy
• Application Number:
  US08/968,867
• Time in Patent Office: 811 Days
• Field of Search: 347/40, 347/43, 347/37, 347/15
• US Class Current: 347/40
• CPC Class Codes: B41J 2/1752 Mounting within the printer
• CPC Class Codes: B41J 2/17526 Electrical contacts to the cartridge
• 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: B41J 2/5056 using dot arrays providing selective dot disposition modes, e.g. different dot densities for high speed and high-quality printing, array line selections for multi-pass printing, or dot shifts for character inclination B41J2/2132 takes precedence
• CPC Class Codes: B41J 3/54 with two or more sets of type or printing elements B41J3/60 takes precedence
• CPC Class Codes: G06K 15/107 Mask selection

Abstract

At least two different pixel densities are used for different printing devices--such as inkjet pens--that operate concurrently, or different printing steps that proceed concurrently, to produce respective image swaths in a single, pixel-based printing machine. The different print devices or steps produce image swaths of respective different swath heights. In one form of the invention, the taller-swath-height printing device operates at lower pixel density, spreading its colorant over a greater area while printing-medium advance keeps pace with operation of the shallower-swath-height printing device. This procedure allows more drying and penetrating time for the colorant applied by the taller-swath device, thereby improving print attributes such as bleed, offset, cockle, curl, overall drying time and throughput. In another form of the invention the taller-swath device operates at higher pixel density, providing physical and temporal separation of colorant application from the two printing devices--to avoid adverse interfering effects between reactive inks.

Claims

1. A mixed-swath-height printer for forming images as an assemblage of ink dots at pixel locations on a printing medium;

said printer comprising;

means for holding the print medium;

first printing means, for operating to print on the medium an image swath having a first swath height;

second printing means, for concurrently operating to print on the medium an image swath having a second swath height that is greater than the first swath height;

common supporting means for supporting the first and second printing means together, relative to the print-medium holding means;

means for controlling the first printing means to apply ink to the medium by addressing the pixel locations at a first pixel density, wherein "pixel density" is defined as an actually-addressed fraction of a total number of addressable pixels; and

means for concurrently controlling the second printing means to apply ink to the medium by addressing the pixel locations at a second pixel density that is different from the first pixel density.

2. The printer of claim 1, further comprising:

means for providing relative motion, generally parallel to said swath heights, of the medium with respect to the first and second printing means; and

means for actuating the relative-motion means in conjunction with printing by said first and second printing means.

3. The printer of claim 2, wherein:

the actuating means comprise means for actuating the relative-motion means in alternation with printing by said first and second printing means.

13. The printer of claim 1, wherein:

the first printing means comprise plural discrete printing-means bodies;

the printer further comprises a plurality of arrays of colorant-dispensing devices, and each of said printing-means bodies carries a respective one of the arrays of colorant-dispensing devices;

the plural arrays of colorant-dispensing devices have a common dispensing-device array height substantially equal to the first swath height;

the second printing means comprise at least one array of colorant-dispensing devices having a dispensing-device array height substantially equal to the second swath height; and

the common supporting means comprise a common carriage which carries the first and second printing means in common for scanning together across the medium.

14. The printer of claim 13, wherein:

said plural printing-means bodies comprise three discrete pens.

15. The printer of claim 14:

further comprising a plurality of chromatic-colorant inks; and

wherein each of the plural pens carries a different chromatic-colorant ink respectively.

16. The printer of claim 13:

further comprising black ink; and

wherein the second printing means comprise a pen carrying black ink.

17. The printer of claim 1, wherein:

the first printing means comprise plural colorant-supply chambers and plural arrays of colorant-dispensing devices, in a common printing-means body;

the plural arrays of colorant-dispensing devices are respectively associated with the plural colorant-supply chambers;

said plural arrays of colorant-dispensing devices, have a common array height substantially equal to the first swath height;

the second printing means comprise at least one array of colorant dispensing devices, with an array height substantially equal to the second swath height;

the common supporting means comprise a common carriage which carries the first and second printing means in common for scanning together across the medium.

18. The printer of claim 17:

further comprising plural chromatic colorants; and

wherein each of the plural colorant-supply chambers carries a different chromatic colorant respectively.

4. A mixed-swath-height printer for forming images as an assemblage of ink dots at pixel locations on a printing medium;

said printer comprising;

means for holding the print medium;

first printing means, for operating to print on the medium an image swath having a first swath height;

second printing means, for concurrently operating to print on the medium an image swath having a second swath height that is greater than the first swath height;

common supporting means for supporting the first and second printing means together, relative to the print-medium holding means;

means for controlling the first printing means to apply ink to the medium by addressing the pixel locations at a first pixel density, wherein "pixel density" is defined as an actually-addressed fraction of a total number of addressable pixels;

means for concurrently controlling the second printing means to apply ink to the medium by addressing the pixel locations at a second pixel density that is different from the first pixel density;

means for providing relative motion, generally parallel to said swath heights, of the medium with respect to the first and second printing means; and

means for actuating the relative-motion means in conjunction with printing by said first and second printing means; and

wherein said concurrently-controlling means comprise means for controlling the second printing means to apply ink to the medium by addressing the pixel locations at a second pixel density that is lower than the first pixel density.

5. The printer of claim 4, wherein:

said second swath height has a value; and

the actuating means comprise means for actuating the relative-motion means to provide a relative shift, of the medium with respect to the first and second printing means, that is less than said second swath height value.

6. The printer of claim 5, wherein:

the actuating means comprise means for actuating the relative-motion means to provide a relative shift, of the medium with respect to the first and second printing means, that is one-third of said second swath height value.

7. The printer of claim 5, wherein:

the first swath height has a value; and

the actuating means comprise means for actuating the relative-motion means to provide a relative shift, of the medium with respect to the first and second printing means, that is less than said first swath height value.

8. The printer of claim 5, wherein:

the first swath height has a value; and

the actuating means comprise means for actuating the relative-motion means to provide a relative shift, of the medium with respect to the first and second printing means, that is one-half of said first swath height value.

9. The printer of claim 5, wherein:

the first swath height has a value; and

the actuating means comprise means for actuating the relative-motion means to provide a relative shift, of the medium with respect to the first and second printing means, that is equal to said first swath height value.

10. The printer of claim 5, wherein:

the first swath height has a first height value;

the second swath height has a second height value;

the actuating means comprise means for actuating the relative-motion means to provide a relative shift, of the medium with respect to the first and second printing means, that is;

a first fraction of the first swath height value, and is

a second fraction of the second swath height value; and

each of the first and second fractions has a numerator of 1 and a denominator that is a respective integer.

12. The printer of claim 5, wherein:

the printing medium is effectively subdivided, for printing, into successive height segments equal to said relative shift; and

on the medium, each height segment equal to said relative shift is addressed during more operations of said second printing means than of said first printing means.

11. A mixed-swath-height printer for forming images as an assemblage of ink dots at pixel locations on a printing medium;

said printer comprising;

means for holding the print medium;

first printing means, for operating to print on the medium an image swath having a first swath height;

second printing means, for concurrently operating to print on the medium an image swath having a second swath height that is greater than the first swath height;

common supporting means for supporting the first and second printing means together, relative to the print-medium holding means;

means for controlling the first printing means to apply ink to the medium by addressing the pixel locations at a first pixel density;

means for concurrently controlling the second printing means to apply ink to the medium by addressing the pixel locations at a second pixel density that is different from the first pixel density;

means for providing relative motion, generally parallel to said swath heights, of the medium with respect to the first and second printing means; and

means for actuating the relative-motion means in conjunction with printing by said first and second printing means; and

wherein;

said concurrently-controlling means comprise means for controlling the second printing means to apply ink to the medium by addressing the pixel locations at a second pixel density that is lower than the first pixel density;

the first swath height has a first height value;

the second swath height has a second height value;

the actuating means comprise means for actuating the relative-motion means to provide a relative shift, of the medium with respect to the first and second printing means, that is less than said second swath height value;

the actuating means comprise means for actuating the relative-motion means to provide a relative shift, of the medium with respect to the first and second printing means, that is;

a first fraction of the first swath height value, and is

a second fraction of the second swath height value; and

the first and second fractions are 1/2 and 1/3 respectively.

19. A method of forming images as an assemblage of ink dots at pixel locations on a printing medium;

said method comprising the steps of;

printing on the medium an image swath having a first swath height;

concurrently printing on the medium an image swath having a second swath height that is greater than the first swath height;

controlling the first-swath-height printing step to apply ink to the medium by addressing the pixel locations at a first pixel density, wherein "pixel density" is defined as an actually-addressed fraction of a total number of addressable pixels; and

concurrently controlling the second-swath-height printing step to apply ink to the medium by addressing the pixel locations at a second pixel density that is different from the first pixel density.

20. The method of claim 19, for printing in plural colorants, and wherein:

the second pixel density is lower than the first pixel density;

said printing and concurrently-printing steps comprise addressing to each pixel, for each colorant, an inking level selected from the group consisting of;

binary color, in which each pixel either receives or does not receive one specific number of dots for each colorant respectively; and

plural-bit color, in which each pixel receives a number of dots, for each colorant respectively, which can vary between zero and 2ⁿ -1 times a specific number of dots for each colorant, where n≧

2 is a number of bits characterizing said plural-bit color.