Fluid ejection device with a through-chip micro-electromechanical actuator

• US 20050264610A1
• Filed: 07/08/2005
• Published: 12/01/2005
• Est. Priority Date: 07/15/1997
• Status: Active Grant

• Current Assignee: Zamtec Limited (Memjet Limited)
• Original Assignee: Kia Silverbrook, Silverbrook Research Pty Limited
• Inventors: Silverbrook, Kia
• Granted Patent: US 7,125,103 B2
• Time in Patent Office: Days
• US Class Current: 347/54
• 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 2/1643 thin film formation by plating
• CPC Class Codes: B41J 2/1645 thin film formation by spincoating
• CPC Class Codes: B41J 2/1648 Production of print heads with thermal bend detached actuators
• CPC Class Codes: B41J 2002/041 Electromagnetic transducer

Abstract

A fluid ejection device includes a substrate that defines a plurality of nozzle chambers. A drive circuitry layer is positioned on one side of the substrate and contains drive circuitry. A structural layer is positioned on an opposite side of the substrate and defines a plurality of ink ejection ports in fluid communication with respective nozzle chambers. A plurality of micro-electromechanical actuators is fast at one end with the substrate and extends into respective nozzle chambers. Each actuator comprises an actuating member that is connected to the drive circuitry and anchored at one end to the substrate. Each actuating member is displaceable between a quiescent position and an active position to eject fluid from the respective ejection ports.

Claims

1. A fluid ejection device that comprises

a substrate that defines a plurality of nozzle chambers;

a drive circuitry layer positioned on one side of the substrate and containing drive circuitry;

a structural layer positioned on an opposite side of the substrate and defining a plurality of ink ejection ports in fluid communication with respective nozzle chambers; and

a plurality of micro-electromechanical actuators fast at one end with the substrate and extending into respective nozzle chambers, each actuator comprising an actuating member that is connected to the drive circuitry and anchored at one end to the substrate, the actuating member being displaceable between a quiescent position and an active position to eject fluid from the respective ejection port.

2. A fluid ejection device as claimed in claim 1, in which at least a portion of each actuating member is of an electrically conductive material that defines a heating circuit configured so that, when the circuit is heated with an electrical current, the actuating member is displaced between the quiescent and active positions, the circuit being connected to the drive circuitry so that the circuit is heated on receipt of an electrical signal from the drive circuitry.

3. A fluid ejection device as claimed in claim 2, in which each heating circuit is of a shape memory alloy.

4. A fluid ejection device as claimed in claim 3, in each actuating member is a laminated structure, with the heating circuit defining one layer of the actuating member.

5. A fluid ejection device as claimed in claim 4, in which each actuating member includes a pre-stressing layer positioned on, and mechanically fast with, the respective heating circuit, the shape memory alloy having a generally planar form when in the austenitic phase and the pre-stressing layer serving to curl the actuating member away from the ejection port when the shape memory alloy is in a martensitic phase, such that, when heated, the shape memory alloy drives the actuating member into a planar form, thereby ejecting a drop of ink from the ejection port.

6. A fluid ejection device as claimed in claim 5, in which the shape memory alloy is a nickel titanium alloy.

7. A fluid ejection device as claimed in claim 5, in which the pre-stressing layer is silicon nitride deposited to generate a pre-stressed condition in the silicon nitride.

8. A fluid ejection device as claimed in claim 5, in which each heating circuit is interposed between the pre-stressing layer and a stress reference layer for the pre-stressing layer.