A novel piezoelectric electro-motional device using a PVF2 multilayer bimorph structure is described. This structure delivers a relatively large bending motion at low applied voltages because of the bimorph action and the thickness of the polymer films. Typically, the bending deflection at the unsupported end of a two-layer bimorph cantilever structure 20 mm in length is 1 mm per 10 volts of dc applied potential across the layers. Frequency response is typically 10 - 102 Hz depending upon cantilever length. Performance is relatively insensitive to temperature over the range 35 to 40. A large range of mechanical-electrical tradeoffs in relatively simple structures using inexpensive material makes these devices potentially attractive for a wide range of applications that require low frequencies and mechanical force, for example: for fine motion control, for displays, for light beam control, and for certain types of electrical circuit control.

Design theory for piezoelectric polymer membrane motional devices is presented. Three types of structures are considered: 1) multilayer structures with a central non-piezoelectric layer, 2) multilayer structures using layers with various thickness in which the electric field is expressed by a approximation of linear spatial dependence, and 3) single layer structures with interdigitated electrodes. The first and second structures feature a reduction in the number of layers with little reduction in motional performance. These approaches are advantageous for structural simplification. The third structure provides a 35 times larger bending displacement than that of the original double layer bimorph using the same layer thickness.

It was found that an oxide power-epoxi resin mixture is an optimum material for surface acoustic wave absorbers oberlayed on LiNb03, Using a SAW device with edge reflection absorbers of this mixture for an FM discriminator, 0.05% distortion at 10.7 MHz center frequency, and 75 KHz frequency deviation, were obtained.

Detailed investigation has been made of a surface acoustic wave FM demodulator in which the phase difference between the input and output signals of a SAW delay device is detected. Total harmonic distortion of the audio output signal is measured to be 0.05%, a value comparable with best commercial practice with demodulators operating at a frequency deviation of 75 KHz with a center frequency of 10.7 MHz. Distortion mainly consists of evenorder harmonic components which are less objectionable to a listener than the odd-order harmonic components found in conventional high quality FM demodulators. Analysis shows that the distortion can be reduced reducing both the amplitude of the SAW spurious signals and the delay time difference between the spurious and main delay signals. The spurious SAW signals of concern included those from direct feed-through, triple-transit echoes, bulk waves, and edge reflections. Techniques for reducing or eliminating these are described. Calculated results are in fairly good agreement with experiment.