Print material level sensing

Patent metadata

Field	Value
Publication number	US-11292264-B2
Application number	US-201916769042-A
Country	US
Kind code	B2
Filing date	Apr 5, 2019
Priority date	Apr 5, 2019
Publication date	Apr 5, 2022
Grant date	Apr 5, 2022

Abstract

A print material level sensor includes a series of print material level sensing devices disposed at intervals to detect the presence of print material at successive depth zones in a container. Each print material level sensing device includes a heater to emit heat at its depth zone and a sensor to sense heat at the depth zone and to output a signal based on the heat sensed. The print material level sensor includes control circuitry to enable supply of electrical power to the heater of any one of the print material level sensing devices in its depth zone and to receive the signal from the respective sensor. The control circuitry includes a comparator to compare a value of the signal to a target value. The control circuitry disables supply of the electrical power to the heater when the value of the signal is at least equal to the target value.

First claim

The invention claimed is:

1. A print material level sensor, comprising:
a series of print material level sensing devices disposed at intervals to detect a presence of a print material at successive depth zones in a container, wherein each print material level sensing device includes a heater to emit heat at its depth zone and a sensor to sense heat at the depth zone and to output a signal based on the heat sensed; and
control circuitry to enable a supply of electrical power to the heater of any one of the print material level sensing devices in its respective depth zone and to receive the signal from the sensor of the print material level sensing device, the control circuitry including a comparator to compare a value of the signal to a target value, wherein the control circuitry disables the supply of the electrical power to the heater when the value of the signal is at least equal to the target value.

2. The print material level sensor of claim 1 , the control circuitry further including a register to store the target value.

3. The print material level sensor of claim 1 , the control circuitry further including a digital to analog converter to convert the target value from a digital value to a first analog signal, wherein the comparator is an analog comparator to receive the first analog signal and to receive the signal output by the sensor as a second analog signal.

4. The print material level sensor of claim 1 , the control circuitry further including an analog to digital converter to convert the signal output by the sensor from an analog signal to a digital sensor value, wherein the comparator is a digital comparator to compare the target value to the digital sensor value.

5. The print material level sensor of claim 1 , the control circuitry further including a switch to stop supply of the electrical power to the heater when an output signal of the comparator indicates that the value of the signal output by the sensor is at least equal to the target value.

6. The print material level sensor of claim 5 , wherein the switch is a field-effect transistor (FET).

7. The print material level sensor of claim 1 , wherein the heater of each print material level sensing device has a switch electrically connected to the heater to turn on or off electrical power to the heater in accordance with a zone select signal.

8. The print material level sensor of claim 1 , wherein the sensor of each print material level sensing device has a switch electrically connected to the sensor to turn on or off transmittal of the signal to the control circuitry in accordance with a zone select signal.

9. The print material level sensor of claim 1 , wherein the control circuitry samples the signal from the sensor after disabling the supply of the electrical power to the heater.

10. The print material level sensor of claim 9 , wherein the control circuitry samples the signal from the sensor after a delay time has expired from disabling the supply of the electrical power to the heater.

11. The print material level sensor of any of claim 1 , the control circuitry including a delay timer to count a delay time starting when the comparator determines that the value of the signal first equals or exceeds the target value and a sample and hold circuit to sample the signal when the delay time has been reached.

12. The print material level sensor of claim 1 , wherein the control circuitry enables the supply of electrical power to the heater of each print material level sensing device in a sequence.

13. The print material level sensor of claim 1 , wherein the series of print material level sensing devices is provided on an elongated strip having an aspect ratio of at least 20.

14. A print material container, comprising:
a chamber to hold a print material;
a series of print material level sensing devices disposed at intervals to detect a presence of the print material at successive depth zones in the chamber, wherein each print material level sensing device includes a heater to emit heat at its depth zone and a sensor to sense heat at the depth zone and to output a signal based on the heat sensed; and
control circuitry to enable a supply of electrical power to the heater of any one of the print material level sensing devices in its respective depth zone and to receive the signal from the sensor of the print material level sensing device, the control circuitry including a comparator to compare a value of the signal to a target value, wherein the control circuitry disables the supply of the electrical power to the heater when the value of the signal is at least equal to the target value.

15. The print material container of claim 14 , the control circuitry further including a switch to disable the supply of the electrical power to the heater when an output signal of the comparator indicates that the value of the signal output by the sensor is at least equal to the target value.

16. The print material container of claim 14 , wherein the control circuitry enables the supply of electrical power to the heater of each print material level sensing device in a sequence.

17. The print material container of claim 14 , wherein the heater of each print material level sensing device has a switch electrically connected to the heater to turn on or off electrical power to the heater in accordance with a zone select signal.

18. The print material container of claim 14 , wherein the sensor of each print material level sensing device has a switch electrically connected to the sensor to turn on or off transmittal of the signal to the control circuitry in accordance with a zone select signal.

19. The print material container of claim 14 , wherein the control circuitry samples the signal from the sensor after disabling the supply of the electrical power to the heater.

20. A method, comprising:
for each of a series of print material level sensing devices provided at successive depth zones of a chamber holding a print material;
supplying electrical power to a heater of the print material level sensing device to emit heat at the depth zone of the print material level sensing device;
sensing heat received by a thermal sensor of the print material level sensing device at the depth zone;
comparing a signal from the thermal sensor to a target value to determine whether the depth zone has been heated to a target temperature;
disabling the supply of the electrical power to the heater when it is determined that the depth zone has been heated to at least the target temperature;
counting a delay time from the disabling of the supply of the electrical power; and
reading the signal from the thermal sensor after the delay time has been reached to determine whether the print material is present at the depth zone.

Assignees

• Hewlett Packard Development Co

Inventors

• Anderson Daryl E
• Gardner James Michael

Classifications

• B41J2002/17579

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• B41J2/17566 Primary

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• B41J2/17553

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