# US 8,540,330 B2 · System and method to compensate for an inoperative inkjet in an inkjet printer

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- Number: US 8,540,330 B2
- Document ID: US8540330B2
- Status: Granted
- Kind: B2
- Application number: 12/891,217
- Filed: 2010-09-27
- Published: 2012-03-29
- Granted: 2013-09-24
- Earliest claimed: 2010-09-27
- Assignees: Xerox Corporation
- Applicants: Bhaskar T. Ramakrishnan; Brent E. Fleming; Joel Chan
- Inventors: Bhaskar T. Ramakrishnan; Brent E. Fleming; Joel Chan
- Web page: https://patentgrep.com/patent/US8540330B2

## CPC

- B41J 2/17593: {Supplying ink in a solid state}
- B41J 2/04508: {aiming at correcting other parameters}
- B41J 2/0451: {for detecting failure, e.g. clogging, malfunctioning actuator}
- B41J 2/04573: {Timing; Delays}
- B41J 2/04581: {controlling heads based on piezoelectric elements}
- B41J 2/2139: {Compensation for malfunctioning nozzles creating dot place or dot size errors (generating single droplets or particles on demand by pressure, e.g. electromechanical transducers B41J2/045)}
- B41J 2/2142: {Detection of malfunctioning nozzles (generating single droplets or particles on demand by pressure, e.g. electromechanical transducers B41J2/045, B41J2/05; jet deflection sensors B41J2/125; for cleaning purposes B41J2/16579)}
- B41J: TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS

## Abstract

An inkjet printer has been developed, which identifies one or more printing metrics and selects a corrective operation for image data. After application of the corrective operation to image data, firing signals are generated with reference to the modified image data to compensate for an inoperative inkjet in a printhead of the inkjet printer.

## Claims

### Claim 1

A printer comprising:
an image processor configured to identify at least one pixel in image data that corresponds to an inoperative inkjet in a printhead, to identify at least one metric for a portion of the image data that corresponds to one or more inkjets positioned to compensate for the inoperative inkjet, to select a corrective operation from a plurality of corrective operations, which includes an elimination of pixels corrective operation comprised of eliminating the at least one pixel and another pixel corresponding to an operable inkjet and at least one other corrective operation different than the elimination of pixels corrective operation, in response to the at least one metric being greater than a predetermined threshold, and to apply the selected corrective operation to the image data; and
a controller configured to generate firing signals to operate the one or more inkjets positioned to compensate for the inoperative inkjet with reference to the image data to which the image processor has applied the selected corrective operation.

### Claim 2 (depends on 1)

The printer of claim 1 wherein the image processor is further configured to select the elimination of pixels corrective operation in response to a dither level for the portion of the image data that corresponds to the one or more inkjets positioned to compensate for the inoperative inkjet being greater than a predetermined threshold.

### Claim 3 (depends on 1)

The printer of claim 1 wherein the image processor is further configured to identify the at least one metric by identifying an ink drop mass and an image resolution for the portion of the image data that corresponds to the one or more inkjets positioned to compensate for the inoperative inkjet.

### Claim 4 (depends on 1)

The printer of claim 1 wherein the image processor is further configured to select the corrective operation from the plurality of corrective operations with reference to at least one of a printer identifier, a printhead configuration identifier, an ink drop mass, an image resolution, an image color content, an image density, and a print mode.

### Claim 5 (depends on 1)

The printer of claim 1 wherein the at least one metric identifies the at least one identified pixel as being a black pixel in one of a textual area and graphic area.

### Claim 6 (depends on 1)

The printer of claim 1, the at least one other corrective operation different than the elimination of pixels corrective operation in the plurality of corrective operations further comprising:
generating at least one substitute pixel for the identified at least one pixel without eliminating another pixel corresponding to an operable inkjet.

### Claim 7 (depends on 6)

The printer of claim 6, the generation of at least one substitute pixel further comprising:
generating a first complementary pixel; and
generating a second complementary pixel.

### Claim 8 (depends on 7)

The printer of claim 7 wherein the first complementary pixel corresponds to a magenta ink color and the second complementary pixel corresponds to one of a cyan ink color and a yellow ink color.

### Claim 9 (depends on 6)

The printer of claim 6, the generation of at least one substitute pixel further comprising:
generating a first complementary pixel corresponding to a magenta ink color;
generating a second complementary pixel corresponding to a cyan ink color; and
generating a third complementary pixel corresponding to a yellow ink color, the first, second, and third complementary pixels being generated in response to the at least one identified pixel being a black pixel.