Evaluating print head nozzle condition

Patent metadata

Field	Value
Publication number	US-9956763-B2
Application number	US-201415304750-A
Country	US
Kind code	B2
Filing date	Apr 23, 2014
Priority date	Apr 23, 2014
Publication date	May 1, 2018
Grant date	May 1, 2018

Abstract

The present subject matter relates to evaluating print head nozzle condition of a plurality of nozzle columns. Each of the plurality of nozzle columns comprises a set of nozzles. A plurality of drive bubble detect modules are activated, by a timing circuit coupled to each of the plurality of nozzle columns upon occurrence of at least a first predetermined time instant and a second predetermined time instant. For each of the plurality of nozzle columns, test results for a nozzle of the nozzle column are registered by the corresponding drive bubble detect module. Test results obtained based on impedances measured across a nozzle associated with the nozzle column corresponding to a drive bubble detect module are registered by the drive bubble detect module at the first predetermined time instant and the second predetermined time instant. The print head nozzle condition of the nozzle is evaluated based on the test results.

First claim

We claim:

1. A method for evaluating a print head nozzle condition of a plurality of nozzle columns on a print die, wherein each of the plurality of nozzle columns comprises a respective set of nozzles, the method comprising:
obtaining a first time instant stored in a first time repository on the print die, and a second time instant stored in a second time repository on the print die;
activating, by a timing circuit on the print die and coupled to each of the plurality of nozzle columns, a plurality of drive bubble detect modules on the print die at the first time instant and the second time instant, wherein each of the plurality of drive bubble detect modules is coupled to a corresponding nozzle column from among the plurality of nozzle columns;
for each of the plurality of nozzle columns, registering by the corresponding drive bubble detect module, test results for a nozzle of the nozzle column in memory elements on the print die, wherein the test results are based on impedances measured across the nozzle at the first time instant and the second time instant; and
evaluating the print head nozzle condition of the nozzle based on the test results.

2. The method as claimed in claim 1 , wherein the test results include a first test result and a second test result, and wherein the first test result is obtained by comparing impedance corresponding to the impedance measured at the first time instant with a threshold impedance.

3. The method as claimed in claim 2 , wherein the second test result is obtained by comparing impedance corresponding to the impedance measured at the second time instant with the threshold impedance.

4. The method as claimed in claim 2 , wherein the first test result and the second test result are in the form of a logical output.

5. The method as claimed in claim 2 , wherein:
the first test result is indicative of whether a drive bubble persisted at the first time instant; and
the second test result is indicative of whether the drive bubble collapsed and ink within an ink chamber associated with the nozzle replenished by the second time instant.

6. The method as claimed in claim 1 , wherein the first time instant and the second time instant are measured with respect to a firing pulse based on clocked signal.

7. The method as claimed in claim 1 , wherein the first time instant stored in the first time repository represents a time at which a printing fluid flows out of the nozzle, and the second time instant stored in the second time repository represents a time at which a printing fluid flows into the nozzle.

8. The method as claimed in claim 6 , wherein the measuring of the first time instant and the second time instant with respect to the firing pulse comprises:
using a counter clocked by the clocked signal to measure an elapsed time from the firing pulse to the first time instant;
registering a first test result of the test results in a first memory element of the memory elements in response to the counter indicating the elapsed time from the firing pulse to the first time instant;
using the counter clocked by the clocked signal to measure an elapsed time from the first time instant to the second time instant; and
registering a second test result of the test results in a second memory element of the memory elements in response to the counter indicating the elapsed time from the first time instant to the second time instant.

9. A print die comprising:
a plurality of nozzle columns on the print die, wherein each of the plurality of nozzle columns comprises a respective set of nozzles;
a first time repository on the print die to store a first time instant, and a second time repository on the print die to store a second time instant;
a plurality of drive bubble detect modules provided onto the print die, wherein each of the plurality of drive bubble detect modules is coupled to each of the set of nozzles of a corresponding nozzle column from among the plurality of nozzle columns, wherein each of the drive bubble detect modules is to:
register, for a nozzle of the corresponding set of nozzles at the first time instant obtained from the first time repository, a first test result obtained based on an impedance measured across the nozzle;
register, for the nozzle at the second time instant obtained from the second time repository, a second test result obtained based on an impedance measured across the nozzle; and
determine a nozzle condition of the nozzle based on the first test result and the second test result; and

a timing circuit on the print die and coupled to each of the plurality of drive bubble detect modules, wherein the timing circuit is to activate the plurality of drive bubble detect modules at the first time instant and the second time instant, to register the first test result and the second test result.

10. The print die as claimed in claim 9 , wherein each of the plurality of drive bubble detect modules is to provide the first test result and the second test result as a binary output.

11. The print die as claimed in claim 10 , wherein each of the plurality of drive bubble detect modules is to determine that the nozzle is functioning properly when the first test result is a logical high output and the second test result is a logical low output.

12. The print die as claimed in claim 9 , wherein each of the plurality of drive bubble detect modules further comprises a memory element for registering the first test result and the second test result.

13. The print die as claimed in claim 9 , wherein the timing circuit is to measure the first time instant and the second time instant with respect to an occurrence of a firing pulse.

14. The print die as claimed in claim 9 ,
wherein the timing circuit further comprises a multiplexer for selecting one of the first time repository and the second time repository.

15. The print die as claimed in claim 9 , wherein the first time instant stored in the first time repository represents a time at which a printing fluid flows out of the nozzle, and the second time instant stored in the second time repository represents a time at which a printing fluid flows into the nozzle.

16. The print die as claimed in claim 13 , wherein the timing circuit comprises:
a counter clocked by a clocked signal to:
measure an elapsed time from the firing pulse to the first time instant, and
measure an elapsed time from the first time instant to the second time instant,

the timing circuit to cause each of the drive bubble detect modules to:
register the first test result in a first memory element on the print die in response to the counter indicating the elapsed time from the firing pulse to the first time instant;
register the second test result in a second memory element on the print die in response to the counter indicating the elapsed time from the first time instant to the second time instant.

17. A print die comprising:
a plurality of nozzle columns on the print die, wherein each of the plurality of nozzle columns comprises a set of nozzles;
a plurality of drive bubble detect modules on the print die, wherein each of the plurality of drive bubble detect modules is coupled to the set of nozzles of a corresponding nozzle column from among the plurality of nozzle columns, wherein each of the plurality of drive bubble detect modules is to:
register, for a nozzle from among the set of nozzles of the corresponding nozzle column, a first test result in a first memory element on the print die, based on comparing a first measure of impedance associated with the nozzle at a first predetermined time instant;
regis

Assignees

• Hewlett Packard Development Co

Inventors

• Anderson Daryl E
• Martin Eric T

Classifications

• B41J2/0451 Primary

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

• B41J2/0458

  controlling heads based on heating elements forming bubbles · CPC title

• B41J2/14153

  Structures including a sensor · CPC title

• B41J2/04541

  Specific driving circuit · CPC title

• B41J2/04555

  detecting current · CPC title