Liquid drop emitter with split thermo-mechanical actuator

• US 20060082615A1
• Filed: 12/05/2005
• Published: 04/20/2006
• Est. Priority Date: 06/27/2003
• Status: Active Grant

• Current Assignee: Antonio Cabal, John A. Lebens
• Original Assignee: Antonio Cabal, John A. Lebens
• Inventors: Lebens, John A., Cabal, Antonio
• Granted Patent: US 7,144,099 B2
• Time in Patent Office: Days
• US Class Current: 347/56
• CPC Class Codes: B41J 2/14427 Structure of ink jet print heads with thermal bend detached actuators
• CPC Class Codes: B41J 2/1628 dry etching
• CPC Class Codes: B41J 2/1639 sacrificial molding
• CPC Class Codes: B41J 2/1648 Production of print heads with thermal bend detached actuators
• CPC Class Codes: B41J 2002/14346 Ejection by pressure produced by thermal deformation of ink chamber, e.g. buckling

Abstract

An apparatus for a liquid drop emitter, especially for use in an ink jet printhead, is disclosed. A chamber filled with a liquid, a nozzle and a thermo-mechanical actuator, extending into the chamber from at least one wall of the chamber is disclosed. A movable element of the thermo-mechanical actuator is configured with a bending portion which bends when heated, the bending portion having at least one actuator opening for passage of the liquid. Apparatus is adapted to apply heat pulses to the bending portion resulting in rapid deflection of the movable element, ejection of a liquid drop, and passage of liquid through the at least one actuator opening. A movable element configured as a cantilever or as a beam extending from anchor walls of the chamber is disclosed. The thermo-mechanical actuator may be formed as a laminate structure including a layer constructed of a deflector material having a high coefficient of thermal expansion and that is electrically resistive, for example, titanium aluminide. Apparatus adapted to apply heat pulses comprising a resistive heater formed in the deflector material in the bending portion is also disclosed.

Claims

1. A liquid drop emitter comprising:

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

(b) a thermo-mechanical actuator, extending into the chamber from at least one wall of the chamber, and having a movable element residing in a first position proximate to the nozzle;

(c) the movable element having a bending portion which bends when heated, the bending portion having at least one actuator opening in the chamber that is open through the bending portion to permit passage of the liquid through the at least one actuator opening; and

(d) apparatus adapted to apply heat pulses to the bending portion actuator resulting rapid deflection of the movable element to a second position, ejection of a liquid drop, and passage of liquid through the at least one actuator opening.

2. The liquid drop emitter of claim 1 wherein the liquid drop emitter is a drop-on-demand ink jet printhead and the liquid is an ink for printing image data.

3. The liquid drop emitter claim 1 wherein the thermo-mechanical actuator includes a deflector layer constructed of a deflector material having a high coefficient of thermal expansion and a low expansion layer, attached to the deflector layer, constructed of a low expansion material having a low coefficient of thermal expansion.

4. The liquid drop emitter claim 3 wherein the deflector material is electrically resistive and the apparatus adapted to apply a heat pulse includes a resistive heater formed in the deflector layer.

5. The liquid drop emitter claim 4 wherein the deflector material is titanium aluminide.

6. The liquid drop emitter of claim 1 wherein the movable element is an elongated structure having a lengthwise axis and the at least one actuator opening is substantially symmetric about the lengthwise axis.

7. The liquid drop emitter of claim 1 wherein the nozzle has a cross sectional area A_n for passage of the liquid, the movable element has one or more actuator openings having a total cross sectional area A_m for passage of the liquid, wherein A_n<

A_m<

10A_n.

8. A liquid drop emitter comprising:

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

(b) a thermo-mechanical actuator, having a cantilevered element extending from an anchor wall of the chamber and a free end residing in a first position proximate to the nozzle;

(c) the cantilevered element having a bending portion which bends when heated, the bending portion having at least one actuator opening in the chamber that is located in a center of the bending portion and is open through the bending portion to permit passage of the liquid through the at least one actuator opening; and

(d) apparatus adapted to apply heat pulses to the bending portion actuator resulting rapid deflection of the free end to a second position, ejection of a liquid drop, and passage of liquid through the at least one actuator opening.

9. The liquid drop emitter of claim 8 wherein the liquid drop emitter is a drop-on-demand ink jet printhead and the liquid is an ink for printing image data.

10. The liquid drop emitter claim 8 wherein the thermo-mechanical actuator is a laminate including a deflector layer constructed of a deflector material having a high coefficient of thermal expansion and a low expansion layer, attached to the deflector layer, constructed of a low expansion material having a low coefficient of thermal expansion.

11. The liquid drop emitter claim 10 wherein the deflector material is electrically resistive and the apparatus adapted to apply a heat pulse includes a resistive heater formed in the deflector layer.

12. The liquid drop emitter claim 11 wherein the deflector material is titanium aluminide.

13. The liquid drop emitter of claim 11 wherein the resistive heater is configured to have a first resistor segment and a second resistor segment each extending from the anchor wall and the at least one actuator opening is located between the first and second resistor segments.

14. The liquid drop emitter of claim 13 wherein the at least one actuator opening includes slot portions that define a central stationary portion of the cantilevered element that does not bend when the bending portion is heated.

15. The liquid drop emitter of claim 14 wherein the anchor wall of the chamber has an upper anchor wall portion and the upper anchor wall portion is extended along the central stationary portion of the cantilevered element.

16. The liquid drop emitter of claim 14 wherein the thermal conductivity of the deflector material is substantially greater than the thermal conductivity of the low expansion material and the low expansion material is removed in the central stationary portion of the cantilevered element.

17. The liquid drop emitter of claim 14 wherein the thermal conductivity of the low expansion material is substantially greater than the thermal conductivity of the deflector material and the deflector material is removed in the central stationary portion of the cantilevered element.

18. The liquid drop emitter of claim 14 wherein the substrate further includes a heat sink portion and a third material having high thermal conductivity is laminated to the central stationary portion and brought into good thermal contact with the heat sink portion.

19. The liquid drop emitter of claim 8 wherein the nozzle has a cross sectional area A_n for passage of the liquid, the cantilevered element has one or more actuator openings having a total cross sectional area A_m for passage of the liquid, wherein A_n<

A_m<

10A_n.