Testing a printhead

Patent metadata

Field	Value
Publication number	US-9527276-B2
Application number	US-201314760417-A
Country	US
Kind code	B2
Filing date	Jan 23, 2013
Priority date	Jan 23, 2013
Publication date	Dec 27, 2016
Grant date	Dec 27, 2016

Abstract

A system and method for testing printheads is disclosed. The system comprises an optical sensor mounted on a movable carriage. The optical sensor is moved past a nozzle to be tested on the printhead while the nozzle ejects ink. The output signal of the optical sensor can be used to determine when the trajectory of the ejected ink is improper.

First claim

What is claimed is:

1. A method of testing a printhead, comprising:
positioning an optical sensor on one side of at least one nozzle in the printhead such that a leading edge of a light beam from the optical sensor is spaced apart from the nozzle location;
moving the optical sensor towards the at least one nozzle in a direction perpendicular with the light beam while the optical sensor is taking measurements;
repeatedly ejecting ink drops from the at least one nozzle into the moving light beam;
moving the optical sensor past the nozzle location while the optical sensor is taking measurements such that a trailing edge of the light beam is on the other side of the nozzle location and is spaced apart from the nozzle location;
analyzing the optical sensor measurements to determine the ejected ink trajectory.

2. The method of claim 1 , wherein the optical sensor is moved at a constant velocity.

3. The method of claim 1 , wherein the ink is ejected from the at least one nozzle in bursts with a gap between the bursts.

4. The method of claim 3 , wherein the bursts comprise between 4 and 20 drops.

5. The method of claim 3 , wherein the gap between the bursts is between 100 and 2000 microseconds.

6. The method of claim 1 , wherein optical sensor moves in a direction parallel with a printing direction for the printhead.

7. The method of claim 1 , wherein the nozzle is disabled when the ejected ink trajectory is improper.

8. The method of claim 1 , wherein the light beam has a diameter between 0.05 and 1 inches.

9. A printer, comprising
at least one printhead mount to mount a printhead, the printhead having a plurality of nozzles to eject ink onto media;
an optical sensor mounted on a movable carriage, the optical sensor comprising a light source and a light detector, the light source emitting a light beam towards the light detector;
the optical carriage movable between a first position and a second position such that a full width of the light beam passes underneath the plurality of nozzles when the carriage is moved from the first position to the second position;
a processor coupled to memory, the memory comprising computer readable instructions that, when executed by the processor, cause the printer to test a printhead mounted in the at least one printhead mount by:
ejecting ink from at least one of the plurality of nozzles while moving the carriage from the first position to the second position and while the optical sensor is taking measurements;
analyzing an output from the light detector to determine the ejected ink trajectory.

10. The printer of claim 9 , wherein the carriage is moved at a constant velocity.

11. The printer of claim 9 , wherein the ink is ejected from the at least one of the plurality of nozzles in bursts with a gap between the bursts.

12. The printer of claim 11 , wherein the bursts comprise between 4 and 20 drops.

13. The printer of claim 9 , wherein the carriage moves in a direction parallel with a printing direction for the printer.

14. The printer of claim 9 , wherein the nozzle is disabled when the ejected ink trajectory is improper.

15. The printer of claim 9 , wherein the light beam has a diameter between 0.5 and 1 inches.

16. A printer, comprising
at least one printhead having a plurality of nozzles to eject ink onto media;
an optical sensor, the optical sensor comprising a light source and a light detector, the light source emitting a light beam towards the light detector;
a carriage movable between a first position and a second position such that a full width of the light beam passes through and perpendicular to a line of fire for each of the plurality of nozzles;
a processor coupled to memory, the memory comprising computer readable instructions that, when executed by the processor, cause the printer to test at least one of the nozzles by:
repeatedly ejecting ink from a nozzle under test into the light beam while the light beam is moving relative to and across the line of fire of the nozzle under test and while the optical sensor is taking measurements; and
analyzing an output from the light detector to determine whether the ejected ink from the nozzle under test is following a correct trajectory.

17. The printer of claim 16 , wherein the carriage supports the optical sensor to move the optical sensor through the line of fire of the nozzles.

18. The printer of claim 16 , wherein the processor is programmed to control the nozzle under test to eject a continuous stream of ink drops while the light beam is passing through the nozzle's line of fire.

19. The printer of claim 16 , wherein the processor is programmed to control the nozzle under test to eject bursts of ink drops with gaps in between the bursts while the light beam is passing through the nozzle's line of fire.

20. The printer of claim 16 , wherein the processor is programmed to analyze a shape of a light detector output curve to determine whether the nozzle under test is ejecting ink on the correct trajectory.

Assignees

• Hewlett Packard Development Co Lp

Inventors

• Portela Mala Laura
• Soriano Fosas David

Classifications

• B41J2/0456

  detecting drop size, volume or weight · CPC title

• B41J2/04561

  detecting presence or properties of a drop in flight · CPC title

• B41J19/20

  Positive-feed character-spacing mechanisms (controlled by escapements B41J19/52) · CPC title

• B41J29/393

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

• B41J2/0451 Primary

  for detecting failure, e.g. clogging, malfunctioning actuator · CPC title