System and method to detect ink drop directionality degradation and perform remedial measures to prevent failing inkjets in printheads

Patent metadata

Field	Value
Publication number	US-11059289-B1
Application number	US-201916724459-A
Country	US
Kind code	B1
Filing date	Dec 23, 2019
Priority date	Dec 23, 2019
Publication date	Jul 13, 2021
Grant date	Jul 13, 2021

Abstract

A directionality detector is configured for use in an inkjet printer to attenuate the effects of ink drying in the nozzles of a printhead during printing operations. The directionality detector includes an optical sensor that generates image data of a test pattern formed on media by the printer, a diffuser that emits humidified air toward the media before the media is printed, and a controller operatively connected to the optical sensor and diffuser. The controller is configured compare the image data of the test pattern to stored image data of the test pattern printed at a previous time and determine whether any difference between the two images is greater than a predetermined threshold. The controller then operates the diffuser to direct humidified air toward the media passing the diffuser using the differences between the stored image data of the test pattern and the image data of the test pattern.

First claim

What is claimed is:

1. An inkjet printer comprising:
a plurality of printheads, each printhead having a plurality of inkjets operatively connected to a supply of ink;
a media transport for moving media past the printheads in a process direction;
an optical sensor positioned so the media passes the optical sensor after the media passes the plurality of printheads, the optical sensor being configured to generate image data of the media after the media has passed the plurality of printheads;
a diffuser positioned so the media passes the diffuser before the media passes the plurality of printheads, the diffuser being configured to emit humidified air toward the media passing the diffuser; and
a controller operatively connected to the plurality of printheads, the media transport, the optical sensor, and the diffuser, the controller being configured to:
operate the media transport to move media past the diffuser, the plurality of printheads, and the optical sensor in the process direction;
operate the inkjets in the printheads to eject ink drops toward the media as the media passes the printheads to form a test pattern on the media;
receive from the optical sensor image data of the media after the test pattern has been formed on the media;
compare the image data of the media to stored image data of the test pattern printed at a previous time, identify a difference between the image data of the media and the stored image data of the test pattern, and determine whether the identified difference is greater than a predetermined threshold; and
operate the diffuser to direct humidified air toward the media passing the diffuser when the difference between the image data of the media and the stored image data of the test pattern is greater than the predetermined threshold.

2. The inkjet printer of claim 1 , the controller being further configured to:
identify a difference between the image data of the media and the stored image data of the test pattern for each inkjet that formed a portion of the test pattern on the media; and
operating the diffuser using the identified differences for the inkjets that formed the test pattern on the media.

3. The inkjet printer of claim 2 , the diffuser further comprising:
an array of transducers and a supply of water adjacent the array of transducers; and the controller is further configured to:
operate the transducers in the array of transducers at a predetermined level to direct uniformly humidified air toward the media passing the diffuser.

4. The inkjet printer of claim 3 , the controller being further configured to operate the transducers independently using the identified differences for the inkjets that formed the test pattern on the media.

5. The inkjet printer of claim 4 , the controller being further configured to:
independently operate the transducers by varying an amplitude of a signal provided to one or more of the transducers to alter an amount of moisture in the humidified air produced by the one or more transducers.

6. The inkjet printer of claim 4 , the controller being further configured to:
independently operate the transducers by providing an energizing signal to less than all of the transducers to produce humidified air from some areas of the diffuser and not from other areas of the diffuser.

7. The inkjet printer of claim 6 , the controller being further configured to:
independently operate the transducers by varying an amplitude of a signal provided to one or more of the transducers to alter an amount of moisture in the humidified air produced by the one or more transducers.

8. A method of operating an inkjet printer comprising:
operating with a controller a media transport to move media past a plurality of printheads in a process direction;
operating with the controller the plurality of printheads to form a test pattern on the media with one or more inkjets in the printheads;
generating with an optical sensor image data of the test pattern formed on the media after the media has passed the plurality of printheads;
comparing with the controller the image data of the media received from the optical sensor to stored image data of the test pattern printed at a previous time;
identifying with the controller a difference between the image data of the media and the stored image data of the test pattern;
determining whether the identified difference is greater than a predetermined threshold; and
operating with the controller a diffuser to direct humidified air toward the media passing the diffuser before the media passes the plurality of printheads when the difference between the image data of the media and the stored image data of the test pattern is greater than the predetermined threshold.

9. The method of claim 8 , the identification of the difference further comprising:
identifying a difference between the image data of the media and the stored image data of the test pattern for each inkjet that formed a portion of the test pattern on the media; and
operating the diffuser with the controller using the identified differences for the inkjets that formed the test pattern on the media.

10. The method of claim 9 further comprising:
operating with the controller transducers in an array of transducers in the diffuser at a predetermined level to direct uniformly humidified air toward the media passing the diffuser.

11. The method of claim 10 further comprising:
operating the transducers in the array of transducers independently of one another using the identified differences for the inkjets that formed the test pattern on the media.

12. The method of claim 11 , the independent operation of the transducers further comprising:
varying with the controller an amplitude of an energizing signal provided to one or more of the transducers to alter an amount of moisture in the humidified air produced by the one or more transducers.

13. The method of claim 11 further comprising:
providing an energizing signal to less than all of the transducers to produce humidified air from some areas of the diffuser and not from other areas of the diffuser.

14. The method of claim 13 further comprising:
varying an amplitude of the energizing signal to one or more of the transducers to alter an amount of moisture in the humidified air produced by the one or more transducers.

15. A directionality degradation detector configured for use in an inkjet printer comprising:
an optical sensor positioned so media passes the optical sensor after a test pattern has been formed on the media by at least a portion of the inkjets in a plurality of printheads, the optical sensor being configured to generate image data of the test pattern on the media;
a diffuser configured to emit humidified air toward the media before the test pattern is formed on the media; and
a controller operatively connected to the optical sensor and the diffuser, the controller being configured to:
receive from the optical sensor image data of the media after the test pattern has been formed on the media;
compare the image data of the media to stored image data of the test pattern printed at a previous time, identify a difference between the image data of the media and the stored image data of the test pattern, and determine whether the identified difference is greater than a predetermined threshold; and
operate the diffuser to direct humidified air toward the media passing the diffuser when the difference between the image data of the media and the stored image data of the test pattern is greater than the predetermined threshold.

16. The directionality degradation detec

Assignees

• Xerox Corp

Inventors

• Praharaj Seemit
• Herrmann Douglas K
• Mcconville Paul J
• Lefevre Jason M
• Liu Chu-Heng
• Vankouwenberg David A
• Levy Michael J
• Hoover Linn C
• Wyble Thomas J
• Meyers John P

Classifications

• B41J2/1707 Primary

  Conditioning of the inside of ink supply circuits, e.g. flushing during start-up or shut-down · CPC title

• B41J2/125 Primary

  Sensors, e.g. deflection sensors {(nozzle clogging detection for cleaning reasons B41J2/16579; detection for compensation for failed nozzles B41J2/2139)} · CPC title

• B41J29/393

  Devices for controlling or analysing the entire machine {; Controlling or analysing mechanical parameters involving printing of test patterns} · CPC title

• B41J2/2146

  for line print heads · CPC title

• B41J2/16585

  for paper-width or non-reciprocating print heads · CPC title