Temperature regulation of fluid ejection printheads

• US 6,634,735 B1
• Filed: 10/19/1999
• Issued: 10/21/2003
• Est. Priority Date: 10/16/1998
• Status: Expired due to Fees

• Current Assignee: Memjet Technology Ltd. (Memjet Limited)
• Original Assignee: Silverbrook Research Pty Limited
• Inventors: Silverbrook, Kia
• Primary Examiner(s): Meier, Stephen D.
• Assistant Examiner(s): TRAN, LY T
• Application Number:
  US09/422,893
• Time in Patent Office: 1,463 Days
• Field of Search: 347/60, 347/17, 347/54, 347/9, 347/10, 347/11, 347/12, 347/14, 347/15, 347/59
• US Class Current: 347/54
• CPC Class Codes: B41J 2/04528 aiming at warming up the head
• CPC Class Codes: B41J 2/04541 Specific driving circuit
• CPC Class Codes: B41J 2/04543 Block driving
• CPC Class Codes: B41J 2/04553 detecting ambient temperature
• CPC Class Codes: B41J 2/04563 detecting head temperature; Ink temperature
• CPC Class Codes: B41J 2/04573 Timing; Delays
• CPC Class Codes: B41J 2/04585 controlling heads based on thermal bent actuators
• CPC Class Codes: B41J 2/04588 using a specific waveform
• CPC Class Codes: B41J 2/04591 Width of the driving signal being adjusted
• CPC Class Codes: B41J 2/04596 Non-ejecting pulses
• CPC Class Codes: B41J 2/04598 Pre-pulse
• CPC Class Codes: B41J 2/14427 Structure of ink jet print heads with thermal bend detached actuators
• CPC Class Codes: B41J 2/1623 bonding and adhesion
• CPC Class Codes: B41J 2/1626 etching
• CPC Class Codes: B41J 2/1628 dry etching
• CPC Class Codes: B41J 2/1631 photolithography
• CPC Class Codes: B41J 2/1632 machining
• CPC Class Codes: B41J 2/1635 dividing the wafer into individual chips
• CPC Class Codes: B41J 2/1639 sacrificial molding
• CPC Class Codes: B41J 2/1642 thin film formation by CVD [chemical vapor deposition]
• CPC Class Codes: B41J 2/1646 : thin film formation by sputtering
• CPC Class Codes: B41J 2/1648 : Production of print heads with thermal bend detached actuators
• CPC Class Codes: B41J 2/175 : Ink supply systems ; Circuit parts therefor
• CPC Class Codes: B41J 2/17513 : Inner structure
• CPC Class Codes: B41J 2/17553 : Outer structure
• CPC Class Codes: B41J 2002/14491 : Electrical connection
• CPC Class Codes: B41J 2202/21 : Line printing

Abstract

A method of operation of a fluid ejection printhead within a predetermined thermal range so as to print an image, wherein the printhead temperature is measured and below a predetermined threshold, the printhead is heated to a desired temperature before printing. Where thermal bend actuators are used in the printhead, heating is controlled so as to be insufficient to cause ejection of fluid.

Claims

1. A method of operating a page width ink jet printhead within a predetermined thermal range so as to print an image, said printhead comprising:

an array of nozzles formed on a substrate, each nozzle including a thermal actuator which is displaceable to eject ink through a nozzle opening of its associated nozzle;

an ink chamber for each said nozzle;

an activation unit for each nozzle for controlling operation of said actuators, each said activation unit comprising a heater element external to said ink chamber of said nozzle;

at least one temperature sensor attached to said substrate for sensing the temperature of said substrate;

a temperature determination unit connected to said at least one temperature sensor, and

an ink ejection drive unit connected to said temperature determination unit and to said printhead;

said method including the steps of;

(a) sensing the temperature of said substrate with said at least one temperature sensor and said temperature determination unit;

(b) said ink ejection drive unit determining if said temperature is below a predetermined threshold;

(c) if said temperature is below said predetermined threshold, performing a preheating step of heating said actuators so that the printhead is heated to a temperature above said predetermined threshold;

(d) controlling said preheating step such that said thermal actuators are heated by pulses of energy less than 160 nJ, which are insufficient to cause the ejection of ink from said printhead, ejection of one ink drop from one said nozzle requiring at least 160 nJ; and

(e) utilizing said printhead to print said image.

2. A method as claimed in claim 1 further comprising the steps of:

(aa) initially sensing an ambient temperature surrounding said printhead;

(ab) setting said predetermined threshold to be said ambient temperature plus a predetermined operational factor amount, said operational factor amount being dependent on said ambient temperature.

3. A method as claimed in claim 1 further comprising the step of:

(e) monitoring said printhead temperature whilst printing said image and when said temperature falls below said predeternined threshold, reheating said actuators so that the temperature of said printhead is again above said predetermined threshold.

4. A method as claimed in claim 1 wherein said step (b) comprises constantly monitoring said printhead temperature whilst heating said printhead.

5. A method as claimed in claim 1 wherein said step (d) further comprises applying a series of short electrical pulses to said thermal actuators, each being insufficient to cause the ejection of ink from said printhead.

9. A method as claimed in claim 1 wherein ejection of one ink drop from one said nozzle requires between 160 and 190 nJ.

6. A page width ink jet printhead comprising:

an array of nozzles formed on a substrate, each nozzle including a thermal actuator which is displaceable to eject ink on demand through a nozzle opening of its associated nozzle;

an activation unit for each nozzle for controlling operation of said actuators, each said activation unit comprising a heater element external to an ink chamber of said nozzle;

at least one temperature sensor attached to said substrate for sensing the temperature of said substrate;

a temperature determinationr unit connected to said at least one temperature sensor;

an ink ejection drive unit connected to said temperature determination unit and to said printhead;

wherein, before an ink ejection operation is begun, said temperature determination unit utilizes an output from said at least one temperature sensor to sense a current temperature of said substrate, and if said temperature is below a predetermined threshold, said ink ejection drive unit outputs a preheat activation signal to generate pulses of enery of less than 160 nJ to heat each said thermal actuator to an extent sufficient to heat said substrate, while being insufficient for the ejection of ink from said array, ejection of one ink drop from one said nozzle requiring at least 160 nJ.

7. A printhead as claimed in claim 6 which includes a plurality of spaced apart temperature sensors on said substrate.

8. A printhead as claimed in claim 6 wherein said array of nozzles is divided into a series of spaced apart groups with at least one temperature sensor per group.

10. A printhead as claimed in claim 6 wherein ejection of one ink drop from one said nozzle requires between 160 and 190 nJ.