Thermoelastic bend actuator using PTFE corrugated heater ink jet printing mechanism

• US 6,312,107 B1
• Filed: 07/10/1998
• Issued: 11/06/2001
• Est. Priority Date: 07/15/1997
• Status: Expired due to Term

• Current Assignee: Memjet Technology Ltd. (Memjet Limited)
• Original Assignee: Silverbrook Research Pty Limited
• Inventors: Silverbrook, Kia
• Primary Examiner(s): Barlow, John
• Assistant Examiner(s): Do, An H.
• Application Number:
  US09/113,127
• Time in Patent Office: 1,215 Days
• Field of Search: 347/20, 347/44, 347/54.56, 347/84.85, 347/47
• US Class Current: 347/54
• CPC Class Codes: B41J 2/14 Structure thereof only for on-demand ink jet heads
• CPC Class Codes: B41J 2/16 Production of nozzles
• CPC Class Codes: B41J 2/1626 etching
• CPC Class Codes: B41J 2/1632 machining
• 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 2/17596 Ink pumps, ink valves

Abstract

A drop on demand inkjet printer which includes a thermal actuator. The thermal actuator is formed of an electrically operable heater element that is encased within actuation material having a high coefficient of thermal expansion. The heater element includes a corugated structure to improve transferral of heat from the heater element to the actuation material and hence increase the speed of actuation of the thermal actuator. The heater element is also of a serpentine or concertina form so as to allow substantially unhindered expansion of the actuation material during heating. One surface of the actuator is hydrophobic and the other surface is hydrophilic, with the heater element constructed form copper encased in polytetrafluoroethylene which is processed to form a hydrophilic surface. The actuator can include a number of layers. One of the layers is conductive material which functions as the heater element. The conductive material is sandwiched between layers of actuation material. The conductive material has a series of slots or holes so as to allow the actuation material to be integrally joined together so as to reduce a likelihood of delamination of the layers.

Claims

1. A thermal actuator comprising a heater element having a low coefficient of thermal expansion surrounded by an actuation material having a high coefficient of thermal expansion wherein said thermal actuator includes first and second layers of actuation material and a third layer of conductive material, at least a portion of which is utilised as a heater element, wherein a part of said conductive material has a series of slots or holes so as to allow said actuation material to be integrally joined together so as to reduce a likelihood of delamination of said layers.

2. A thermal actuator as claimed in claim 1 wherein said heater element is also of a serpentine or concertina form so as to allow substantially unhindered expansion of said actuation material during heating.

3. A thermal actuator as claimed in claim 1 wherein said actuator is utilised in an inkjet nozzle for ejection of ink from a nozzle chamber.

4. A thermal actuator as claimed in claim 1 wherein one surface of said actuator is hydrophobic and another surface is hydrophilic.

5. A thermal actuator as claimed in claim 4 wherein said hydrophilic material is formed by means of processing said hydrophobic material.

6. A thermal actuator as claimed in claim 1 wherein said heater element comprises substantially copper.

7. A thermal actuator as claimed in claim 1 wherein said portion having a series of slots or holes comprises a stiff structural paddle at an end of said actuator.

8. A thermal actuator as claimed in claim 7 wherein said stiff structural paddle includes a regularly spaced array of holes defined therein.

9. A thermal actuator as claimed in claim 1 wherein the said heater element is corrugated so as to improve the transferral of heat from said heater element to said actuation material so as to increase the speed of actuation of the thermal actuator.

10. A thermal actuator as claimed in claim 1, the actuator further including a clamp positioned proximal an end of the actuator which is arranged for attachment to a substrate the clamp being arranged to reduce a likelihood of separation of said actuation material from said substrate.

11. A thermal actuator as claimed in claim 10, wherein said clamp is formed by means of a sacrificial etching process.

12. A thermal bend actuator attached at one end of a substrate said actuator including an actuation material having a high coefficient of thermal expansion said actuator further comprising a stable clamp on top of said actuator at the end attached to said substrate said clamp acting to decrease a likelihood of separation of said actuation material from said substrate.

13. A thermal bend actuator as claimed in claim 12 wherein said actuator is utilised for ejection of ink from a chamber via an ink nozzle.

14. A thermal bend actuator as claimed in claim 13 wherein said clamp forms part of a grill structure for the filtering of ink flow into said chamber for subsequent ejection.

15. A thermal bend actuator as claimed in claim 12 wherein said substrate is fabricated from a silicon wafer and said clamp comprises substantially silicon nitride.

16. A thermal bend actuator as claimed in claim 15 wherein said clamp is formed by means of a sacrificial etching process.