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Thermal bend actuator and control circuitry for a micro-electromechanical device

  • US 6,786,573 B2
  • Filed: 11/17/2003
  • Issued: 09/07/2004
  • Est. Priority Date: 10/16/1998
  • Status: Expired due to Fees
First Claim
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1. A thermal bend actuator which includesa wafer substrate;

  • an elongate actuator arm that is fixed to the substrate at a fixed end, the elongate actuator arm including a heater layer of a conductive material and a dielectric, resiliently flexible layer, the heater layer defining a heater circuit which is connected to an electrical potential;

    a working member that is fixed to an opposite free end of the actuator arm; and

    control logic circuitry that is positioned on the substrate, between, and generally aligned with, the heater layer and the substrate, the control logic circuitry being interconnected between a data input means and the heater circuit and including register circuitry connected to the data input means to generate an enabling signal and firing circuitry connected between the register circuitry and the heater circuit to close the heater circuit on receipt of the enabling signal so that said electrical potential generates a current in the heater circuit, resistively to heat the heater layer, at least the heater layer being of a material having a coefficient of thermal expansion which is such that the heater layer can expand on heating and contract on cooling to do work, the heater layer being positioned so that the elongate actuator arm experiences differential thermal expansion and contraction and thus reciprocally displaces the working member.

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