Method and apparatus for thermal control of an ink jet printhead

• US 6,299,273 B1
• Filed: 07/14/2000
• Issued: 10/09/2001
• Est. Priority Date: 07/14/2000
• Status: Expired due to Term

• Current Assignee: Funai Electric Co., Ltd. (Funai Electric Holdings Company Limited)
• Original Assignee: Lexmark International Incorporated (Ninestar Corporation)
• Inventors: Jones, Christopher Dane, Mulay, Shirish Padmaker, Anderson, Frank Edward, Spencer, William Shannon, Dyer, Stanley
• Primary Examiner(s): Le, N.
• Assistant Examiner(s): Nghiem, Michael P.
• Application Number:
  US09/617,136
• Time in Patent Office: 452 Days
• Field of Search: 347/14, 347/17, 347/18, 347/19
• US Class Current: 347/17
• CPC Class Codes: B41J 2/04506 aiming at correcting manufacturing tolerances
• CPC Class Codes: B41J 2/0454 involving calculation of temperature
• CPC Class Codes: B41J 2/04553 detecting ambient temperature
• CPC Class Codes: B41J 2/04563 detecting head temperature; Ink temperature
• CPC Class Codes: B41J 2/0458 controlling heads based on heating elements forming bubbles
• CPC Class Codes: B41J 2/17546 electronically
• CPC Class Codes: B41J 2202/17 Readable information on the head

Abstract

A method of controlling a temperature of a print chip of a printhead in an ink jet printer includes providing the printer with a memory device. The print chip is provided with and at least one ink-jetting resistor. The printhead is provided with at least one substrate heater and a heatsink attached to the print chip. Power is applied to the substrate heater and/or the ink-jetting resistor. Temperature data associated with the print chip is recorded during the applying step. A thermal resistance value of the print chip to the heatsink and/or a thermal capacitance value associated with the printhead is calculated dependent upon the recorded temperature data. The thermal resistance value of the print chip to the heatsink and/or the thermal capacitance value associated with the printhead are stored in the memory device. A temperature of the heatsink is measured based upon the thermal resistance value of the print chip to the heatsink, the thermal capacitance value associated with the printhead, a temperature of the print chip, an ambient temperature, and/or a thermal resistance value associated with the heatsink. A level of power to be applied to the substrate heater is set dependent upon the thermal resistance value of the print chip to the heatsink and/or the thermal capacitance value associated with the printhead, and the temperature of the heatsink.

Claims

1. A method of controlling a temperature of a print chip of a printhead in an ink jet printer, said method comprising the steps of:

providing the printer with a memory device;

providing the printhead with at least one substrate heater;

providing the print chip with at least one ink-jetting resistor;

providing the printhead with a heatsink attached to the print chip;

applying power to at least one of said substrate heater and said ink-jetting resistor;

recording temperature data associated with the print chip during said applying step;

calculating at least one of a thermal resistance value of the print chip to said heatsink and a thermal capacitance value associated with the printhead, said calculating being dependent upon said recorded temperature data;

storing the at least one of a thermal resistance value of the print chip to said heatsink and a thermal capacitance value associated with the printhead in said memory device;

measuring a temperature of said heatsink based upon at least one of;

the at least one of a thermal resistance value of the print chip to said heatsink and a thermal capacitance value associated with the printhead;

a temperature of the print chip; and

a thermal resistance value associated with said heatsink; and

setting a level of power to be applied to said substrate heater, said setting step being dependent upon said temperature of said heatsink and the at least one of a thermal resistance value of the print chip to said heatsink and a thermal capacitance value associated with the printhead.

2. The method of claim 1, comprising the further step of providing a temperature sensing device one of attached to the print chip and formed integrally with the print chip, wherein each of said recording step and said measuring step are based upon an output of said temperature sensing device.

3. The method of claim 2, comprising the further step of determining the ambient temperature based upon said output of said temperature sensing device, and wherein said setting step is dependent upon said detennined ambient temperature.

4. The method of claim 1, wherein said calculating step includes dividing a change in temperature of said print chip by an amount of power applied in said applying step to thereby yield a measured thermal resistance value.

5. The method of claim 4, wherein said calculating step includes:

computing a temperature difference between a peak temperature of the print chip and an initial temperature of the print chip;

determining a cooling detection temperature by adding a predetermined fraction of the temperature difference to the initial temperature of the print chip;

ascertaining a time period between a time of termination of said applying step and a time at which a temperature of the print chip reaches the cooling detection temperature; and

producing a thermal capacitance value by dividing the time period by the measured thermal resistance value.

6. The method of claim 5, wherein said initial temperature of the print chip is approximately equal to said temperature of said heatsink.

7. The method of claim 1, comprising the further step of attaching said memory device to the printhead.

8. The method of claim 1, comprising the further step of installing the printhead in the printer, wherein said applying, recording, calculating and storing steps are all performed substantially immediately after said installing step.

9. The method of claim 1, wherein said applying step comprises applying said power to said ink-jetting resistor while the printhead is in a spit location.

10. The method of claim 1, wherein said measuring step comprises at least one of monitoring and predicting said temperature of said heatsink.

11. A method of controlling a temperature of a print chip of a printhead in an ink jet printer, said method comprising the steps of:

providing a memory device within the printer;

providing the printhead with at least one substrate heater;

applying power to said substrate heater;

recording temperature data associated with the print chip during said applying step;

calculating at least one of a thermal resistance value associated with the printhead and a thermal capacitance value associated with the printhead, said calculating including dividing a change in temperature of said print chip by an amount of power applied in said applying step to thereby yield a measured thermal resistance value;

storing the at least one of a thermal resistance value associated with the printhead and a thermal capacitance value associated with the printhead in said memory device; and

setting a level of power to be applied to said substrate heater, said setting step being dependent upon the at least one of a thermal resistance value associated with the printhead and a thermal capacitance value associated with the printhead.

12. The method of claim 11, comprising the further steps of:

attaching a heatsink to the print chip; and

one of monitoring and predicting a temperature of said heatsink;

wherein said setting step is dependent upon said temperature of said heatsink.

13. The method of claim 12, wherein said predicting step is dependent upon the at least one of a thermal resistance value associated with the printhead and a thermal capacitance value associated with the printhead.

14. The method of claim 11, comprising the further step of providing a temperature sensing device attached to the print chip, wherein said recording step is based upon an output of said temperature sensing device.

15. The method of claim 14, comprising the further step of determining an ambient temperature based upon said output of said temperature sensing device, and wherein said setting step is dependent upon said determined ambient temperature.

16. The method of claim 11, wherein said calculating step includes:

computing a temperature difference between a peak temperature of the print chip and an initial temperature of the print chip;

determining a cooling detection temperature by adding a predetermined fraction of the temperature difference to the initial temperature of the print chip;

ascertaining a time period between a time of termination of said applying step and a time at which a temperature of the print chip reaches the cooling detection temperature; and

producing a thermal capacitance value by dividing the time period by the measured thermal resistance value.

17. The method of claim 16, wherein said initial temperature of the print chip is approximately equal to a temperature of a heatsink attached to the print chip.

18. The method of claim 11, comprising the further step of attaching said memory device to the printhead.

19. The method of claim 11, comprising the further step of installing the printhead in the printer, wherein said applying, recording, calculating and storing steps are all performed substantially immediately after said installing step.

20. An ink jet printer comprising:

a printhead including;

a substrate heater;

a print chip; and

a heatsink attached to said print chip;

a memory device storing a thermal resistance value of said print chip to said heatsink; and

a controller configured to;

retrieve the thermal resistance value from said memory device; and

set a level of power to be applied to said substrate heater dependent upon a temperature of said heatsink and the thermal resistance value of said print chip to said heatsink.

21. The ink jet printer of claim 20, wherein said print chip includes a temperature sensing device configured to output a temperature of said print chip, said controller being configured to predict said temperature of said heatsink based upon said temperature of said print chip.