Indications of similarity for drop detector signals

Patent metadata

Field	Value
Publication number	US-10625500-B2
Application number	US-201616097969-A
Country	US
Kind code	B2
Filing date	Jul 25, 2016
Priority date	Jul 25, 2016
Publication date	Apr 21, 2020
Grant date	Apr 21, 2020

Abstract

In an example, a print apparatus includes a printhead carriage to receive a printhead comprising a print agent ejection nozzle, a drop detector to acquire a signal indicative of variations in a parameter detected by the drop detector over a period of drop detection, a memory to hold a print agent ejection signature, and processing circuitry. The processing circuitry includes a convolution module to convolve the drop detector signal with the print agent ejection signature, and the processing circuitry is to determine, from an output of the convolution module, an indication of similarity between the drop detector signal and the print agent ejection signature.

First claim

The invention claimed is:

1. A print apparatus comprising:
a printhead carriage to receive a printhead comprising a print agent ejection nozzle;
a drop detector to acquire a signal indicative of variations in a parameter detected by the drop detector over a period of drop detection;
a memory to hold a plurality of print agent ejection signatures; and
processing circuitry comprising a convolution module to convolve the drop detector signal with the print agent ejection signatures, wherein the processing circuitry is to identify, from an output of the convolution module, the print agent ejection signature with which the drop detector signal is most similar.

2. A print apparatus according to claim 1 in which the drop detector comprises a radiation detector to detect radiation intensity, and the parameter comprises a radiation intensity value.

3. A print apparatus according to claim 1 in which the processing circuitry comprises a nozzle assessment module to determine, based on the print agent ejection signature with which the drop detector signal is most similar, an indication of an operational status of the nozzle from which the print agent was ejected.

4. A print apparatus according to claim 1 in which the processing circuitry is to determine the print agent ejection signature with which the drop detection similar is most similar from an indication of similarity from a peak height in the output of the convolution module for each print agent ejection signature.

5. A print apparatus according to claim 1 in which the drop detector signal and the print agent ejection signatures are normalized prior to convolution.

6. A method comprising:
acquiring a signal from a detector to detect a passage of a quantity of print agent ejected from a printhead nozzle;
filtering, using a processor, the acquired signal by convolving the acquired signal with a model print agent passage signal; and
determining, using a processor and based on the filtered signal, an indication of an operational status of the printhead nozzle.

7. The method of claim 6 in which determining an indication of an operational status of the printhead nozzle comprises determining a similarity parameter based on the filtered signal.

8. The method of claim 6 further comprising selecting, using a processor, a model print agent passage signal from a plurality of model print agent passage signals based on a property of a print agent of an intended print agent ejection, and determining a filtered signal using the selected model print agent passage signal(s).

9. The method of claim 6 further comprising determining, using a processor, a filtered signal using each of a plurality of model print agent passage signals, and identifying the model print agent passage signal which is the closest match to the acquired signal.

10. The method of claim 9 in which identifying the model print agent passage signal which is the closest match to the acquired signal comprises determining the filtered signal having the highest peak.

11. A tangible machine readable medium comprising instructions which, when executed by a processor, cause the processor to:
determine a property of print agent to be dispensed by a printhead in an ejection event;
identify a print agent ejection signature associated with that property;
acquire a drop detector output signal following an attempt to dispense a quantity of print agent in the ejection event; and
determine, by convolving the print agent ejection signature with the drop detector output signal, an indication of success of the ejection event.

12. A tangible machine readable medium according to claim 11 further comprising a data store, the data store comprising a plurality of print agent ejection signatures, each print agent ejection signature being associated with a property comprising at least one of a print agent color and a print agent volume.

13. A tangible machine readable medium according to claim 12 in which the data store comprises a plurality of print agent ejection signatures associated with a common set of properties.

Assignees

• Hewlett Packard Development Co

Inventors

• Tuset Pere
• Vilajosana Xavier
• Cabello Sheila

Classifications

• B41J2/165

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

• B41J2/16579

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

• B41J29/38

  Drives, motors, controls or automatic cut-off devices for the entire printing mechanism · CPC title

• B41J2/195

  for monitoring ink quality · CPC title

• B41J2/04561 Primary

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