Determining a time instant for an impedance measurement

Patent metadata

Field	Value
Publication number	US-9776395-B2
Application number	US-201415306737-A
Country	US
Kind code	B2
Filing date	Apr 30, 2014
Priority date	Apr 30, 2014
Publication date	Oct 3, 2017
Grant date	Oct 3, 2017

Abstract

In an example, a method for determining an issue in an inkjet nozzle includes providing an initial fire pulse for firing a nozzle, and receiving the initial fire pulse as a delayed fire pulse at a primitive of the nozzle. The method includes firing the nozzle with the delayed fire pulse, and determining a first time instant following the delayed fire pulse for taking a first impedance measurement across the nozzle.

First claim

What is claimed is:

1. A method for determining an issue in an inkjet nozzle, the method comprising:
providing an initial fire pulse for firing a nozzle;
receiving the initial fire pulse as a delayed fire pulse at a primitive of the nozzle;
firing the nozzle with the delayed fire pulse; and
determining a first time instant following the delayed fire pulse for taking a first impedance measurement associated with the nozzle.

2. A method as in claim 1 , further comprising determining a second time instant following the delayed fire pulse for taking a second impedance measurement associated with the nozzle.

3. A method as in claim 1 , wherein firing the nozzle comprises the nozzle generating a drive bubble, the method further comprising:
comparing a voltage corresponding with the first impedance measurement with a threshold voltage; and
obtaining a first test result based on the comparing, the first test result to indicate whether the drive bubble is present within the nozzle at the first time instant.

4. A method as in claim 3 , further comprising:
second comparing a voltage corresponding with the second impedance measurement with the threshold voltage; and
obtaining a second test result based on the second comparing, the second test result to indicate whether the drive bubble has collapsed within the nozzle by the second time instant.

5. A method as in claim 1 , wherein determining a first time instant following the delayed fire pulse comprises:
communicating the delayed fire pulse from the primitive to a drive bubble detect measurement circuit through a tri-state device within the primitive.

6. A method as in claim 5 , wherein communicating the delayed fire pulse from the primitive to a drive bubble detect measurement circuit through a tri-state device comprises:
enabling the tri-state device by loading data into a data latch of the primitive and placing an enable signal on a drive bubble detect enable bus.

7. A print head comprising:
a primitive including a print nozzle and a tri-state device, the primitive to receive a delayed fire pulse to fire the nozzle, and the tri-state device to communicate the delayed fire pulse to a drive bubble detect (DBD) module on a print die of the print head; and
the DBD module to determine, based on the delayed fire pulse, a first time instant following the firing of the nozzle at which to perform a first DBD impedance measurement associated with the nozzle.

8. A print head as in claim 7 , further comprising:
a plurality of primitives arranged along a nozzle column; and
a compensated fire pulse bus running along the length of the column through each primitive and coupled to an output of a tri-state device in each primitive.

9. A print head as in claim 8 , further comprising a DBD enable bus running along the length of the column through each primitive to carry an enable signal to each tri-state device in the plurality of primitives.

10. A print head as in claim 8 , wherein the compensated fire pulse bus couples the output of each tri-state device with the DBD module.

11. A print head as in claim 7 , further comprising:
a data latch of the primitive to receive data to enable the tri-state device; and
a delay latch of the primitive to receive the delayed fire pulse and to transfer the delayed fire pulse to an input of the tri-state buffer.

12. A print head as in claim 7 , the DBD module to further determine a second time instant following the firing of the nozzle at which to perform a second DBD impedance measurement associated with the nozzle, the print head further comprising:
an ink_out time repository to store an ink_out time result determined from the first DBD measurement; and
an ink_in time repository to store an ink_in time result determined from the second DBD measurement.

13. A print head as in claim 12 , further comprising a threshold source to provide a threshold voltage to compare with a voltage associated with the nozzle to determine the ink_in time and the ink_out time.

14. A printer comprising:
a print nozzle to fire upon receiving a delayed fire pulse;
a sensor within the print nozzle;
a drive bubble detect (DBD) module to determine a condition on the print nozzle based on a DBD impedance measurement associated with the print nozzle and taken with the sensor at a time instant following the delayed fire pulse; and
a tri-state device to communicate the delayed fire pulse to the DBD module.

15. A printer as in claim 14 , wherein the time instant is selected from the group consisting of a first time instant at which a drive bubble is expected to be present within the print nozzle, and a second time instant at which the drive bubble is expected to have collapsed.

Assignees

• Hewlett Packard Development Co Lp

Inventors

• Anderson Daryl E
• Martin Eric T
• Fricke Peter James

Classifications

• B41J2/16579

  Detection means therefor, e.g. for nozzle clogging · CPC title

• B41J2/0458

  controlling heads based on heating elements forming bubbles · CPC title

• B41J2/0451 Primary

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

• B41J2/04598

  Pre-pulse · CPC title

• B41J2/165

  Prevention {or detection} of nozzle clogging, e.g. cleaning, capping or moistening for nozzles · CPC title