Determining the existence of point defects in print apparatuses

Patent metadata

Field	Value
Publication number	US-12130575-B2
Application number	US-202218051333-A
Country	US
Kind code	B2
Filing date	Oct 31, 2022
Priority date	Oct 31, 2022
Publication date	Oct 29, 2024
Grant date	Oct 29, 2024

Abstract

A print apparatus is disclosed. The print apparatus includes a photoconductive surface to receive a latent image representative of an image to be printed onto a printable substrate; a charging component to apply a voltage is to be applied to the photoconductive surface as the charging component moves relative to the photoconductive surface; and processing circuitry to receive data indicative of a measurement of a first current resulting from the voltage applied by the charging component; determine, responsive to detecting an increase in the measured first current relative to a reference current, the increase being greater than a first defined threshold current, that there exists a point defect under affecting the latent image; and generate instruction data responsive to determining that there exists a point defect under affecting the latent image. A method and a machine-readable medium are also disclosed.

First claim

The invention claimed is:

1. A print apparatus comprising:
a rotatable photoconductor having a photoconductive surface to receive a latent image representative of an image to be printed onto a printable substrate;
a charging component to apply a voltage to the photoconductive surface as the photoconductor rotates about an axis; and
processing circuitry to:
receive data indicative of a measurement of current resulting from the voltage applied by the charging component;
determine sample current values corresponding to respective rotation angle positions of the photoconductor about the axis;
filter the sample current values;
determine, responsive to detecting a spike in the filtered sample current values being greater than a threshold, that there exists a point defect affecting the latent image; and
generate instruction data responsive to determining that there exists a point defect affecting the latent image.

2. A print apparatus according to claim 1 , wherein filtering the sample current values includes applying a low-pass filter.

3. A print apparatus according to claim 2 , wherein applying a low pass filter includes applying a moving average for a window size.

4. A print apparatus according to claim 1 , wherein filtering the sample current values includes applying a differentiator filter.

5. A print apparatus according to claim 1 , wherein
determining, responsive to detecting a spike in the filtered sample current values being greater than a threshold, that there exists a point defect affecting the latent image includes:
responsive to determining that the spike is greater than a first defined threshold, that there exists a point defect affecting the latent image;
responsive to determining that the spike is less than the first defined threshold current, compare the spike to a second defined threshold current, the second defined threshold current being lower than the first defined threshold current; and
determine, responsive to determining that the spike is greater than the second defined threshold current, that there exists a point defect affecting the latent image.

6. A print apparatus according to claim 5 , wherein
the second threshold corresponds to a noise level threshold.

7. A print apparatus according to claim 1 , wherein the instruction data comprises data to instruct a device to generate an alert to be delivered to a user interface.

8. A method comprising:
applying a voltage from a charging surface onto a rotatable photoconductor of a print apparatus;
obtaining data indicative of a measurement of a charging current resulting from applying the voltage, wherein data includes sample current values corresponding to respective rotation angle positions of the photoconductor about an axis;
filtering the sample current values;
responsive to detecting a spike in the filtered sample current value being greater than a threshold, determining the photoconductive surface includes a point defect; and
generating instruction data to instruct a recipient device to notify an operator of the presence of the point defect.

9. A method according to claim 8 , further comprising:
generating instruction data comprising an instruction to perform a cleaning task associated with the photoconductive surface.

10. A method according to claim 8 , further comprising:
wherein the photoconductor includes regions used in a printing operation and regions not used in a printing operation and wherein the respective rotation angle positions correspond to regions of the photoconductor used in a printing operation.

11. A method according to claim 8 , further comprising:
determining, based on a respective rotation angle position of a spike, an approximate location of the point defect relative to the photoconductive surface.

12. A method according to claim 8 ,
wherein determining the photoconductive surface includes a point defect, responsive to detecting a spike in the filtered measured current value being greater than a threshold, includes:
iteratively comparing the spike to a threshold amount, the threshold amount decreasing with each iteration from a maximum threshold amount to a minimum threshold amount; and
responsive to determining that the spike is greater than a threshold amount in one of the iterations, determining that the photoconductive surface includes a point defect.

13. A method according to claim 8 , wherein filtering the sample current values includes applying a low-pass filter.

14. A method according to claim 13 , wherein applying a low pass filter includes applying a moving average for a window size.

15. A method according to claim 8 , wherein filtering the sample current values includes applying a differentiator filter.

16. A machine-readable medium comprising instructions which, when executed by a processor, cause the processor to:
receive data indicative of a current measurement associated with a voltage applied onto a photoconductive surface of a rotatable photoconductor of a print apparatus, wherein the data includes sample current values corresponding to respective rotation angle positions of the photoconductor about an axis;
filtering the data;
determine whether a spike in the filtered data is greater than a threshold amount; and
responsive to determining that a spike is greater than a threshold amount, generate instruction data to cause a recipient to be alerted to the current increase.

17. A machine-readable medium according to claim 16 , wherein filtering the data includes applying a low-pass filter.

18. A machine-readable medium according to claim 17 , wherein applying a low pass filter includes applying a moving average for a window size.

19. A machine-readable medium according to claim 16 , wherein filtering the data includes applying a differentiator filter.

Assignees

• Hewlett Packard Development Co

Inventors

• Assenheimer Michel
• Shoshani Asaf
• Barak Naama
• Shalev Dorit

Classifications

• G03G15/0163 Primary

  primary transfer to the final recording medium · CPC title

• G03G15/553

  Monitoring or warning means for exhaustion or lifetime end of consumables, e.g. indication of insufficient copy sheet quantity for a job · CPC title

• G03G15/5037

  the characteristics being an electrical parameter, e.g. voltage · CPC title

• G03G15/0216

  by bringing a charging member into contact with the member to be charged, e.g. roller, brush chargers · CPC title

• G03G21/0094 Primary

  fatigue treatment of the photoconductor · CPC title