Thermal bend actuator with spatial thermal pattern

• US 6,938,991 B2
• Filed: 07/06/2004
• Issued: 09/06/2005
• 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): GORDON, RAQUEL YVETTE
• Application Number:
  US10/884,888
• Publication Number:
  US 20040246308A1
• Time in Patent Office: 427 Days
• Field of Search: 347/54, 347/68, 347/69, 347/70, 347/71, 347/72, 347/50, 347/40, 347/20, 347/44, 347/47, 347/27, 347/63, 399/261, 361/700, 298/901, 310328-330
• US Class Current: 347/54
• CPC Class Codes: B05D 2201/00 Polymeric substrate or laminate
• CPC Class Codes: B05D 3/08 by flames
• 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 2/04571 detecting viscosity
• 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 2/14 Structure thereof only for on-demand ink jet heads
• 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 2/1629 wet 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 2002/14419 : Manifold
• CPC Class Codes: B41J 2002/14491 : Electrical connection
• CPC Class Codes: Y10T 29/49345 : Catalytic device making

Abstract

A thermal actuator for a micro-electromechanical device such as an inkjet printer nozzle. The actuator has: (a) a base element; (b) a cantilevered element including a thermo-mechanical bender portion extending from the base element and a free end tip residing in a first position, the thermo-mechanical bender portion having a base end adjacent the base element and a free end adjacent the free end tip; and (c) apparatus adapted to apply a heat pulse having a spatial thermal pattern directly to the thermo-mechanical bender portion, causing the deflection of the free end tip of the cantilevered element to a second position, and wherein said spatial thermal pattern results in a substantially greater temperature increase of the base end than the free end of the thermo-mechanical bender portion. By designing the actuator such that the material with a high coefficient of thermal expansion heats with a predetermined spatial thermal pattern concentrated toward the base of the cantilever beam, the paddle end movement is greater and faster. The ink above the paddle is given the necessary pressure such that the ink in the bulging meniscus has sufficient momentum to break the surface tension and form a drop.

Claims

1. A thermal actuator for a micro-electromechanical device comprising:

(a) a base element;

(b) a cantilevered element including a thermo-mechanical bender portion extending from the base element and a free end tip residing in a first position, the thermo-mechanical bender portion having a base end adjacent the base element and a free end adjacent the free end tip; and

(c) apparatus adapted to apply a heat pulse having a spatial thermal pattern directly to the thermo-mechanical bender portion, causing the deflection of the free end tip of the cantilevered element to a second position, and wherein said spatial thermal pattern results in a substantially greater temperature increase of the base end than the free end of the thermo-mechanical bender portion.

2. The thermal actuator of claim 1 wherein the apparatus adapted to apply a heat pulse comprises a patterned thin film resistor layer.

3. The thermal actuator of claim 2 wherein the spatial thermal pattern results in part from spatially modifying the conductivity of the thin film resistor layer.

4. The thermal actuator of claim 1 wherein the thermo-mechanical bender portion includes a first deflector layer constructed of a first material having a high coefficient of thermal expansion and a second layer, attached to the first deflector layer, constructed of a second material having a low coefficient of thermal expansion.

5. The thermal actuator of claim 4 wherein the first material is electrically resistive having a first sheet resistance and the apparatus adapted to apply a heat pulse comprises a resistor pattern formed in the first deflector layer.

6. A liquid drop emitter comprising:

(a) a chamber, formed in a substrate, filled with a liquid and having a nozzle for emitting drops of the liquid;

(b) a thermal actuator having a cantilevered element including a thermo-mechanical bender portion extending from a wall of the chamber and a free end tip residing in a first position proximate to the nozzle, the thermo-mechanical bender portion having a base end adjacent the base element and a free end adjacent the free end tip; and

(c) apparatus adapted to apply a heat pulse having a spatial thermal pattern directly to the thermo-mechanical bender portion causing a rapid deflection of the free end tip and ejection of a liquid drop, and wherein said spatial thermal pattern results in a substantially greater temperature increase of the base end than the free end of the thermo-mechanical bending portion.

7. The liquid drop emitter of claim 6 wherein the liquid drop emitter is a drop-on-demand ink jet printhead and the liquid is ink for printing image data.

8. The liquid drop emitter of claim 6 wherein the apparatus adapted to apply a heat pulse comprises a patterned thin film resistor layer.

9. The liquid drop emitter of claim 8 wherein the spatial thermal pattern results in part from spatially modifying the conductivity of the thin film resistor layer.

10. The liquid drop emitter of claim 9 wherein the thermo-mechanical bender portion includes a first deflector layer constructed of a first material having a high coefficient of thermal expansion and a second layer, attached to the first deflector layer, constructed of a second material having a low coefficient of thermal expansion.

11. The liquid drop emitter of claim 10 wherein the first material is electrically resistive having a first sheet resistance and the apparatus adapted to apply a heat pulse comprises a resistor pattern formed in the first deflector layer.

12. A thermal actuator for a micro-electromechanical device comprising:

(a) a base element;

(b) a cantilevered element including a thermo-mechanical bender portion extending from the base element to a free end tip residing at a first position, the thermo-mechanical bender portion having a base end adjacent the base element and a free end adjacent the free end tip, the thermo-mechanical bender portion further including a first deflector layer constructed of a first material having a large coefficient of thermal expansion, a second deflector layer, and a barrier layer constructed of a dielectric material having low thermal conductivity wherein the barrier layer is bonded between the first deflector layer and the second deflector layer; and

(c) apparatus adapted to apply a heat pulse having a spatial thermal pattern directly to the first deflector layer, causing the deflection of the free end tip of the cantilevered element to a second position, followed by restoration of the cantilevered element to the first position as heat diffuses through the barrier layer to the second deflector layer and the cantilevered element reaches a uniform temperature, and wherein said spatial thermal pattern results in a substantially greater temperature increase of the base end than the free end of the first deflector layer.

13. The thermal actuator of claim 12 wherein the apparatus adapted to apply a heat pulse comprises a patterned thin film resistor layer.

14. The thermal actuator of claim 13 wherein the spatial thermal pattern results in part from spatially modifying the conductivity of the thin film resistor layer.

15. The thermal actuator of claim 14 wherein the first material is electrically resistive having a first sheet resistance and the apparatus adapted to apply a heat pulse comprises a resistor pattern formed in the first deflector layer.

16. The thermal actuator of claim 15 wherein the second deflector layer is constructed of the first material and the first deflector layer and the second deflector layer are substantially equal in thickness.

17. A liquid drop emitter comprising:

(a) a chamber, formed in a substrate, filled with a liquid and having a nozzle for emitting drops of the liquid;

(b) a cantilevered element including a thermo-mechanical bender portion extending from a wall of the chamber to a free end tip residing at a first position proximate to the nozzle, the thermo-mechanical bender portion having a base end adjacent the base element and a free end adjacent the free end tip, the thermo-mechanical bender portion further including a first deflector layer constructed of a first material having a large coefficient of thermal expansion, a second deflector layer, and a barrier layer constructed of a dielectric material having low thermal conductivity wherein the barrier layer is bonded between the first deflector layer and the second deflector layer; and

(c) apparatus adapted to apply a heat pulse having a spatial thermal pattern directly to the first deflector layer, causing a rapid deflection of the free end tip and ejection of a liquid drop, followed by restoration of the cantilevered element to the first position as heat diffuses through the barrier layer to the second deflector layer and the cantilevered element reaches a uniform temperature, and wherein said spatial thermal pattern results in a substantially greater temperature increase of the base end than the free end of the first deflector layer.

18. The liquid drop emitter of claim 17 wherein the apparatus adapted to apply a heat pulse comprises a patterned thin film resistor layer.

19. The liquid drop emitter of claim 18 wherein the spatial thermal pattern results in part from spatially modifying the conductivity of the thin film resistor layer.

20. The liquid drop emitter of claim 19 wherein the first material is electrically resistive having a first sheet resistance and the apparatus adapted to apply a heat pulse comprises a resistor pattern formed in the first deflector layer.

21. The liquid drop emitter of claim 17 wherein the second deflector layer is constructed of the first material and the first deflector layer and the second deflector layer are substantially equal in thickness.

22. The liquid drop emitter of claim 17 wherein the liquid drop emitter is a drop-on-demand ink jet printhead and the liquid is ink for printing image data.

23. A drop ejection device comprising:

a base;

a chamber for holding liquid to be ejected, the chamber formed on the base and having a nozzle opening;

a thermal bend actuator for ejecting drops of the liquid from the chamber through the nozzle, the bend actuator being configured as a cantilever with one end of the cantilever is anchored to the base and the opposite end supporting a liquid paddle, the actuator having a deflector section constructed of a material having a large coefficient of thermal expansion and a barrier layer constructed of a dielectric material having low thermal conductivity;

wherein,

differential thermal expansion of the deflector section and the barrier layer causes the actuator to bend so that the paddle ejects drops of liquid from the nozzle.

24. The drop ejection device of claim 23 wherein the deflector section is configured for heating to provide a spatial thermal pattern along the cantilever such that the resultant temperature change is greater at the base end of the cantilever than the paddle end of the cantilever.

25. The drop ejection device of claim 24 wherein the deflector section is a first deflector layer and the device further comprises a second deflector layer, and the barrier layer is bonded between the first deflector layer and the second deflector layer such that the spatial heating pattern causes a substantially greater temperature increase of the base end than the free end of the first deflector layer.

26. The drop ejection device of claim 23 wherein the deflector section is a thin film resistor layer and the spatial thermal pattern results in part from spatially modifying the conductivity of the thin film resistor layer.

27. The drop ejection device of claim 26 wherein the second deflector layer is constructed of the same material as the first deflector layer and the second deflector layer is substantially equal in thickness to the first deflector layer.

28. The drop ejection device of claim 26 wherein the liquid drop emitter is a drop-on-demand ink jet printhead and the liquid is ink for printing image data.