Micro-electromechanical actuator with control logic circuitry

• US 7,028,474 B2
• Filed: 09/20/2004
• Issued: 04/18/2006
• 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): Richter, Sheldon J
• Application Number:
  US10/943,925
• Publication Number:
  US 20050039453A1
• Time in Patent Office: 575 Days
• Field of Search: 605/27, 605/28, 605/29, 310/306, 310/307, 310/309
• US Class Current: 60/527
• CPC Class Codes: B41J 2/04505 aiming at correcting alignment
• CPC Class Codes: B41J 2/04516 preventing formation of satellite drops
• CPC Class Codes: B41J 2/04518 reducing costs
• CPC Class Codes: B41J 2/0452 reducing demand in current or voltage
• 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 2/04565 detecting heater resistance
• CPC Class Codes: B41J 2/0457 Power supply level being detected or varied
• 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 2/0459 Height of the driving signal being adjusted
• CPC Class Codes: B41J 2/04591 Width of the driving signal being adjusted
• CPC Class Codes: B41J 2/04593 Dot-size modulation by changing the size of the drop
• 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 2/1628 : 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 2002/14491 : Electrical connection
• CPC Class Codes: B41J 25/005 : for serial printing movements superimposed to character- or line-spacing movements

Abstract

A micro-electromechanical actuator includes a substrate. An elongate actuator arm has a fixed end portion that is fast with the substrate and a free end portion that is spaced from the substrate. The elongate actuator arm incorporates a heating circuit that is connectable to a power supply to heat the actuator arm. At least a portion of the actuator arm is of a material having a coefficient of thermal expansion which is such that the material is capable of thermal expansion to do work. The heating circuit is positioned to generate differential thermal expansion and contraction when heated and subsequently cooled to cause reciprocal displacement of the free end portion of the actuator arm. Control logic circuitry is positioned on the substrate along an elongate region defined on the substrate and interposed between the actuator arm and the substrate. The control logic circuitry is connected to the heating circuit to enable and disable the power supply according to a control signal received by the control logic circuitry.

Claims

1. A micro-electromechanical actuator that comprises

a substrate;

an elongate actuator arm having a fixed end portion that is fast with the substrate and a free end portion that is spaced from the substrate, the elongate actuator arm incorporating a heating circuit that is connectable to a power supply to heat the actuator arm, at least a portion of the actuator arm being of a material having a coefficient of thermal expansion which is such that the material is capable of thermal expansion to do work, the heating circuit being positioned to generate differential thermal expansion and contraction when heated and subsequently cooled to cause reciprocal displacement of the free end portion of the actuator arm; and

control logic circuitry positioned on the substrate along an elongate region defined on the substrate and interposed between the actuator arm and the substrate, the control logic circuitry being connected to the heating circuit to enable and disable the power supply according to a control signal received by the control logic circuitry.

2. A micro-electromechanical actuator as claimed in claim 1, in which the actuator arm is a laminated structure having a first metal layer and a dielectric layer, the first metal layer being interposed between the dielectric layer and the substrate and defining the heating circuit.

3. A micro-electromechanical actuator as claimed in claim 2, in which the actuator arm has a second metal layer that is positioned so that the dielectric layer is interposed between the metal layers, said second metal layer being substantially the same as the first metal layer.

4. A micro-electromechanical actuator as claimed in claim 2, in which the metal layers and the dielectric layer project from the free end of the actuator arm to define a working member and a discontinuity is defined in the first metal layer between the heating circuit and the fluid ejection member.

5. A micro-electromechanical actuator as claimed in claim 2, in which the control logic circuitry defines transfer register circuitry to receive control signals and drive transistor circuitry connected to the transfer register circuitry, the drive transistor circuitry being interposed between the heating circuit and the substrate and being defined by a plurality of traces that are positioned to extend transversely with respect to a longitudinal axis of the actuator arm.

6. A micro-electromechanical actuator as claimed in claim 5, in which the first metal layer defines a series of corrugations that extend transversely with respect to the longitudinal axis of the actuator arm to correspond with the traces.