Indications of similarity for drop detector signals

Patent metadata

Field	Value
Publication number	US-2019092002-A1
Application number	US-201616097969-A
Country	US
Kind code	A1
Filing date	Jul 25, 2016
Priority date	Jul 25, 2016
Publication date	Mar 28, 2019
Grant date	—

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

1 . A print apparatus comprising:
a printhead carriage to receive a printhead comprising a print agent ejection node; 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 comprising a convolution module to convolve the drop detector signal with the print agent ejection signature, wherein 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.

2 . A print apparatus according to claim 1 in which the memory is to hold a plurality of print agent ejection signatures, wherein the processing circuitry comprises a selection module to select a print agent ejection signature to convolve with a drop detector signal obtained following an intended print agent ejection based on at least one of:
a color of the print agent;
a type of the print agent; and
an intended volume of the print agent.

3 . 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.

4 . A print apparatus according to claim 1 in which the memory is to hold a plurality of print agent ejection signatures, wherein the convolution module is to convolve the drop detector signal with a plurality of print agent ejection signatures and the processing apparatus is to identify to which print agent ejection signature the drop detector signal is most similar.

5 . A print apparatus according to claim 1 in which the processing circuitry comprises a nozzle assessment module to determine, based on the indication of similarity, an indication of an operational status of the nozzle from which the print agent was ejected.

6 . A print apparatus according to claim 1 in which the processing circuitry is to determine the indication of similarity from a peak height in the output of the convolution module.

7 . A print apparatus according to claim 1 in which the drop detector signal and the print agent ejection signature are normalised prior to convolution.

8 . A method comprising:
acquiring a signal from a detector to detect 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.

9 . The method of claim 8 in which determining an indication of an operational status of the printhead nozzle comprises determining a similarity parameter based on the filtered signal.

10 . The method of claim 8 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).

11 . The method of claim 8 further comprising determining, using a process 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.

12 . The method of claim 11 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.

13 . 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.

14 . Tangible machine readable medium according to claim 13 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.

15 . Tangible machine readable medium according to claim 14 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

• B41J2/16579

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

• B41J2/04586

  controlling heads of a type not covered by groups B41J2/04575 - B41J2/04585, or of an undefined type · CPC title

• B41J2/04561 Primary

  detecting presence or properties of a drop in flight · 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