Determining an issue in an inkjet nozzle with impedance measurements

Patent metadata

Field	Value
Publication number	US-9701116-B2
Application number	US-201615262248-A
Country	US
Kind code	B2
Filing date	Sep 12, 2016
Priority date	Apr 19, 2012
Publication date	Jul 11, 2017
Grant date	Jul 11, 2017

Abstract

A method for determining an issue in an inkjet nozzle with impedance measurements, includes taking a first impedance measurement to detect a drive bubble with an impedance sensor; and taking a second impedance measurement to detect said drive bubble with said impedance sensor after said first impedance measurement.

First claim

What is claimed is:

1. A printhead, comprising:
a firing chamber comprising a drive bubble formation mechanism; and an impedance sensor positioned in the firing chamber to detect a presence of a drive bubble, the impedance sensor to take a first impedance measurement within said firing chamber after activation of the drive bubble formation mechanism.

2. The printhead of claim 1 , wherein the impedance sensor measures both impedance and resistance to detect the presence of a drive bubble.

3. The printhead of claim 1 , wherein the impedance sensor takes the first impedance measurement within 5 to 35 microseconds after activation of the drive bubble formation mechanism.

4. The printhead of claim 1 , wherein the drive bubble formation mechanism comprises a heater.

5. The printhead of claim 1 , the impedance sensor being located in the firing chamber in a drive bubble formation area of the firing chamber in which the drive bubble formation mechanism forms a drive bubble.

6. The printhead of claim 1 , wherein the impedance sensor comprises a first region and a second region, the first and second regions being at different locations and providing individual impedance readings.

7. The printhead of claim 6 , wherein the first region and second region are located on separate metal plates electrically connected in parallel.

8. The printhead of claim 6 , wherein an output of the impedance sensor comprises a summed output from the first and second regions.

9. The printhead of claim 6 , wherein the first region is closer to the drive bubble thrmation mechanism than is the second region.

10. The printhead of claim 1 , the printhead further comprising a firing demultiplexer to distribute firing signals to different drive bubble formation mechanisms in different firing chambers of the printhead.

11. The printhead of claim 10 , further comprising a sensing multiplexer to pass signals from multiple impedance sensors, each in a firing chamber of the printhead, to a sensing unit.

12. A printhead, comprising:
an array of firing chamber to selectively deposit droplets of to a print medium;
a drive bubble formation mechanism located in each firing chamber; and
an impedance sensor positioned in each firing chamber to detect a presence of a drive bubble.

13. The printhead of claim 12 , wherein each impedance sensor measures both impedance and resistance to detect the presence of a drive bubble.

14. The printhead of claim 13 , wherein the impedance sensor is to take a first impedance measurement within said firing chamber after activation of the drive bubble formation mechanism.

15. The printhead of claim 12 , wherein each impedance sensor comprises a first region and a second region, the first and second regions being at different locations and providing individual readings.

16. The printhead of claim 15 , wherein the first region and second region are located on separate metal plates electrically connected in parallel.

17. The printhead of claim 15 , wherein an output of each impedance sensor comprises a summed output from the first and second regions of that impedance sensor.

18. The printhead of claim 15 , wherein the first region is closer to the drive bubble formation mechanism than is the second region.

19. The printhead of claim 12 , the printhead further comprising a firing demultiplexer to distribute firing signals to different drive bubble formation mechanisms in different tiring chambers of the printhead.

20. The printhead of claim 12 , further comprising, a sensing multiplexer to pass signals from multiple impedance sensors, each in a firing chamber of the printhead, to a sensing unit.

Assignees

• Hewlett Packard Development Co Lp

Inventors

• Van Brocklin Andrew L
• Martin Eric T
• Govyadinov Alexander
• Maxfield David

Classifications

• B41J2/14153 Primary

  Structures including a sensor · CPC title

• B41J2/0451

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

• B41J2/04555

  detecting current · CPC title

• B41J2002/14354

  Sensor in each pressure chamber · CPC title

• B41J29/393

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