Micro-electromechanical integrated circuit device with laminated actuators

1. A micro-electromechanical integrated circuit device comprising:

a substrate;

drive circuitry positioned on the substrate; and

a plurality of elongate actuators, each actuator comprising a fixed end portion fast with the substrate, a free end portion that is spaced from the substrate, and a heating circuit that is connected to the drive circuitry to heat the actuator, wherein

a portion of the actuator is formed of a material having a coefficient of thermal expansion such that the material is capable of performing work by thermal expansion,

the heating circuit is positioned to generate differential thermal expansion and contraction when heated and cooled to cause reciprocal displacement of the free end portion of the actuator,

each actuator 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, and

the drive circuitry is operable to generate drive pulses of first and second widths, the pulses of the first width being sufficient to cause substantial displacement of the free end of the actuator, and the pulses of the second width being insufficient to cause substantial displacement of the free end of the actuator.

2. A micro-electromechanical integrated circuit device as claimed in claim 1 , wherein the drive circuitry includes control and drive circuitry portions positioned on the substrate along respective elongate regions defined on the substrate and interposed between respective actuators and the substrate.

3. A micro-electromechanical integrated circuit device as claimed in claim 2 , wherein each actuator has a second metal layer that is positioned to interpose the dielectric layer between the first and second metal layers, said second metal layer being substantially the same as the first metal layer.

4. A micro-electromechanical integrated circuit device as claimed in claim 2 , wherein the metal layers and the dielectric layer project from the free end portion of each actuator to define a working member and a discontinuity is defined in the first metal layer between the heating circuit and the working member electrically to isolate the working member.

5. A micro-electromechanical integrated circuit device as claimed in claim 2 , wherein the control circuitry defines transfer register circuitry to receive control signals and drive circuitry connected to the transfer register circuitry, the drive circuitry being interposed between the heating circuits and the substrate and being defined by a plurality of traces that are positioned to extend transversely with respect to longitudinal axes of the actuators.

6. A micro-electromechanical integrated circuit device as claimed in claim 4 , further comprising a plurality of nozzle chamber structures positioned on the substrate and defining nozzle chambers and fluid ejection ports in fluid communication with respective nozzle chambers, the substrate defining a plurality of ink inlet channels in fluid communication with respective nozzle chambers, the working members being in the form of fluid ejection members positioned in respective nozzle chambers such that displacement of the actuators results in the ejection of fluid from the fluid ejection ports.