Operating a page width printhead to print an image

• US 6,827,428 B2
• Filed: 08/18/2003
• Issued: 12/07/2004
• 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:
  US10/642,337
• Publication Number:
  US 20040051759A1
• Time in Patent Office: 477 Days
• Field of Search: 347/60, 347/11, 347/12, 347/14, 347/19
• US Class Current: 347/60
• 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 to print an image, wherein the printhead temperature is measured and if the temperature is below a predetermined threshold, the printhead is heated by pulses of energy to a desired temperature above the predetermined threshold temperature before printing. Where thermal bend actuators are used in the printhead, heating is controlled such that the pulses of energy are insufficient to cause ejection of fluid from the printhead and their duration is tuned in accordance with the fluid composition.

Claims

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

an array of nozzles formed on a substrate, each nozzle including a nozzle opening, an associated displaceable thermal actuator for ejecting ink through said nozzle opening, an ink chamber and an activation unit for controlling operation of said actuator;

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 coupled 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 that are insufficient to cause the ejection of ink from said printhead and tuning a duration of said pulses in accordance with a composition of said ink; and

,

(e) utilizing said printhead to print said image.

2. The method as claimed in claim 1, wherein the energy of said pulses in said preheating step is less than 160 nJ and the ejection of one ink drop from one said nozzle requires at least 160 nJ.

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

4. The method as claimed in claim 1, further including the steps of:

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

(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.

5. The method as claimed in claim 1, further including the step of:

(f) monitoring said printhead temperature whilst printing said image and when said temperature falls below said predetermined threshold, reheating said actuators to again raise the temperature of said printhead above said predetermined threshold.

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

7. The method as claimed in claim 1, further including the step of tuning said duration of said energy pulses to compensate for changes in viscosity of said ink with temperature.

8. The method as claimed in claim 7, further comprising retrieving viscosity/temperature relationship data stored in an authentication chip associated with said ink.

9. A page width ink jet printhead comprising:

an array of nozzles formed on a substrate, each nozzle including a displaceable thermal actuator for ejecting ink on demand through a nozzle opening of its associated nozzle;

an activation unit for each nozzle for controlling operation of said actuators,

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;

an ink ejection drive unit coupled 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 energy 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, a duration of said pulses being tuned in accordance with a composition of said ink.

10. The printhead as claimed in claim 9, wherein a plurality of said temperature sensors are spaced apart on said substrate.

11. The printhead as claimed in claim 9, wherein said array of nozzles is divided into a series of spaced apart groups with at least one temperature sensor per group.

12. The printhead as claimed in claim 9, wherein the energy of said pulses is less than 160 nJ and the ejection of one ink drop from one said nozzle requires at least 160 nJ.

13. The printhead as claimed in claim 9, wherein ejection of one ink drop from one said nozzle requires between 160 and 190 nJ.

14. The printhead as claimed in claim 9, further comprising an authentication chip associated with said ink for storing viscosity/temperature relationship data to enable the tuning of the duration of the energy pulses to compensate for changes in viscosity of said ink with temperature.

15. The printhead as claimed in claim 9, wherein each said activation unit comprises a heater element external to said ink chamber of each said nozzle for heating said actuator.