| 摘要 |
An apparatus for and method of operating a thermal actuator for a micromechanical device, especially a liquid drop emitter such as an ink jet printhead, is disclosed. The disclosed thermal actuator comprises a base element and a cantilevered element extending from the base element and normally residing at a first position before activation. The cantilevered element includes a barrier layer constructed of a low thermal conductivity material, bonded between a first deflector layer and a second deflector layer, both of which are constructed of electrically resistive materials having substantially equal coefficients of thermal expansion. The thermal actuator further comprises a first pair of electrodes connected to the first deflector layer and a second pair of electrodes is connected to the second deflector layer for applying electrical pulses to cause resistive heating of the first or second deflector layers, resulting in thermal expansion of the first or second deflector layer relative to the other. Application of an electrical pulse to either pair of electrodes causes deflection of the cantilevered element away from its first position and, alternately, causes a positive or negative pressure in the liquid at the nozzle of a liquid drop emitter. Application of electrical pulses to the pairs of is used to adjust the characteristics of liquid drop emission. The barrier layer exhibits a heat transfer time constant &tgr;B. The thermal actuator is activated by a heat pulses of duration &tgr;P wherein &tgr;P<½&tgr;B.
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