Method and apparatus to regulate temperature of printheads

Patent metadata

Field	Value
Publication number	US-10124582-B2
Application number	US-201114123799-A
Country	US
Kind code	B2
Filing date	Jul 1, 2011
Priority date	Jul 1, 2011
Publication date	Nov 13, 2018
Grant date	Nov 13, 2018

Abstract

An apparatus including an analog memory, a temperature sensor, a comparator, and a pulse circuit. The analog memory is charged to a reference voltage corresponding to a predetermined temperature of a printhead. The temperature sensor measures a thermal voltage of at least one of the plurality of local areas of the printhead. The comparator obtains a comparison result by comparing the reference voltage to the thermal voltage. The pulse circuit selectively transmits a series of warming pulses to the at least one of the plurality of local areas of the printhead based on the comparison result.

First claim

What is claimed is:

1. An apparatus comprising:
an analog memory comprising a capacitor to maintain a reference voltage determined using a wafer test corresponding to a predetermined temperature of a printhead, the reference voltage maintained on non-volatile memory on the printhead;
a temperature sensor to measure a thermal voltage of at least one of a plurality of local areas of the printhead, the capacitor and temperature sensor being electrically coupled to a global timing signal generator that generates timing signals to control a transition between a first state of the apparatus where the analog memory is charged to the reference voltage and a second state of the apparatus;
a comparator to obtain a comparison result by comparing the reference voltage to the thermal voltage; and
a pulse circuit to selectively transmit a series of warming pulses to the at least one of a plurality of nozzles grouped within the at least one of the plurality of local areas of the printhead based on the comparison result.

2. The apparatus of claim 1 , wherein the thermal voltage is measured across a set of forward biased silicon diodes in the at least one of the plurality of local areas.

3. The apparatus of claim 1 , further comprising a control unit to receive the thermal voltage from the temperature sensor and to determine an actual temperature of the at least one of the plurality of local areas of the printhead.

4. The apparatus of claim 1 , further comprising a digital to analog converter to:
generate the reference voltage corresponding to a desired temperature of the printhead; and
charge the analog memory to the reference voltage.

5. The apparatus of claim 1 , wherein the analog memory stores the reference voltage.

6. The apparatus of claim 1 , wherein the analog memory is a capacitor.

7. The apparatus of claim 1 , further comprising a local AND gate associated with the at least one of a plurality of local areas of the printhead to receive the comparison result from the comparator and a signal from the pulse circuit and transmit the warming pulses based on the comparison result.

8. The apparatus of claim 7 , further comprising a unique OR gate associated with at least one of the nozzles grouped within the at least one of a plurality of local areas, wherein the unique OR gate receives the transmitted warming pulse from the AND gate and coordinates firing pulses associated with the at least one of the nozzles with the transmitted warming pulse.

9. The apparatus of claim 1 , wherein the second state is a state where the analog memory transmits the reference voltage to the comparator and the temperature sensor transmits the thermal voltage of at least one of a plurality of local areas of the printhead.

10. A printhead comprising:
a temperature regulating circuitry unit including:
a local analog memory comprising a capacitor charged to a global reference voltage corresponding to a predetermined temperature of the entire printhead, the local analog memory associated with a first of a plurality of local areas along the printhead;
a local temperature sensor to measure a thermal voltage representing an actual temperature of the first local area of the printhead, the capacitor and local temperature sensor being electrically coupled to a global timing signal generator that generates timing signals to control a transition between a first state and a second state of the temperature regulating circuitry unit;
a local comparator to obtain a comparison result by comparing the reference voltage from the local analog memory to a thermal voltage from the local temperature sensor; and
a global warming pulse circuit to selectively transmit a series of warming pulses to the first local area of the printhead based on the comparison result;
wherein:
the reference voltage used to cause the transmission of the series of warming pulses based on the comparison result is determined using a wafer test,
the reference voltage is maintained on non-volatile memory on the printhead, and
the first state is a state where the analog memory is charged to the reference voltage.

11. The printhead of claim 10 , wherein the thermal voltage is measured across a set of forward biased silicon diodes in the first local area.

12. The printhead of claim 10 , further comprising a control unit to receive the thermal voltage from the temperature sensor and to determine an actual temperature of the first local area of the printhead.

13. The printhead of claim 10 , wherein the temperature regulating circuitry unit further includes a digital to analog converter to:
generate the reference voltage corresponding to a desired temperature of the printhead; and
charge the local analog memory to the reference voltage.

14. The printhead of claim 10 , wherein the local analog memory is a capacitor.

15. The printhead of claim 10 , further comprising a local AND gate associated with the first of a plurality of local areas to receive the comparison result from the comparator and a signal from the pulse circuit and transmit the warming pulses based on the comparison result.

16. The printhead of claim 15 , further comprising a unique OR gate associated with at least one of a plurality of nozzles grouped within the first of a plurality of local areas, wherein the unique OR gate receives the transmitted warming pulse from the AND gate and coordinates firing pulses associated with the at least one of the nozzles with the transmitted warming pulse.

17. A printhead comprising:
a temperature regulating circuit comprising:
a local analog memory comprising a capacitor and associated with a unique local area of a plurality of local areas of the printhead, the local analog memory to receive a global reference voltage equal to an operating temperature of all the local areas of the printhead;
a local temperature sensor to measure a temperature of the unique local area and output a voltage proportional to the measured temperature, the capacitor and local temperature sensor being electrically coupled to a global timing signal generator that generates timing signals to control a transition between a first state and a second state of the temperature regulating circuit;
a local comparator to compare the global reference voltage to the output voltage of the local temperature sensor and provide a comparison result; and
a global pulse circuit to, based on the comparison result, selectively transmit at least one warming pulse to at least one of a plurality of nozzles grouped within the unique local area;

wherein:
the global reference voltage used to cause the transmission of the series of warming pulses based on the comparison result is determined using a wafer test,
the global reference voltage is maintained on non-volatile memory on the printhead,
the first state is a state where the analog memory is charged to the reference voltage, and
the second state is a state where the analog memory transmits the reference voltage to the comparator and the temperature sensor transmits the thermal voltage of at least one of a plurality of local areas of the printhead.

18. The printhead of claim 17 , wherein the local temperature sensor is a forward biased silicon diode.

19. The printhead of claim 17 , wherein local analog memory is a capacitor and receives the global reference voltage from a digital to analog converter that produces a differentially driven and buffered voltage that corresponds to the global reference voltage.

20. The printhead of claim 17 , further comprising a local AND gate

Assignees

• Van Brocklin Andrew L
• Hunter Mark
• Fricke Peter James
• Ghozeil Adam L
• Gardner James Michael
• Hewlett Packard Development Co

Inventors

• Van Brocklin Andrew L
• Hunter Mark
• Fricke Peter James
• Ghozeil Adam L
• Gardner James Michael

Classifications

• B41J2/04563 Primary

  detecting head temperature; Ink temperature · CPC title

• B41J2/04588

  using a specific waveform · CPC title

• B41J2/04596

  Non-ejecting pulses · CPC title

• B41J2/04528

  aiming at warming up the head · CPC title

• B41J2/0458

  controlling heads based on heating elements forming bubbles · CPC title