Piezoelectric flexural transducer with graphite fibre layer - comprising fabric impregnated with epoxide] resin, bonded between piezoceramic layers

摘要

Piezoelectric flexural transducer (1) has a graphite fibre (I) layer (2) bonded with an epoxide resin (II) (8) between 2 piezoceramic (III) layers (10,12) having electrodes (14,16) on both sides. The novelty is that the (I) layer comprises fabric impregnated with (II) and its length is at least 3 times its width. Pref (III) layers have a positive temp coefft of the piezo-constant, which is at least 0.35, (0.4-0.7)%/K in the -20 deg C to +60 deg C range. They are PZT (Pb zirconate-titanate) layers. The (I) layer is longer than the 2 (III) layers and has electric terminal, pref bonded Cu foil (18) or a hollow rivet, in the exposed area. A clip (24) on one side connects the 2 outer electrodes (14a, 16a) electrically. Transducer is produced by placing (I) fabric, impregnated with partly cured (II), between 2 polarised (III) layers and bonding by curing (II), pref at elevated temp, (ca 130 deg C). USE/ADVANTAGE - Useful eg in video appts for VTR head position adjustment, valves or blind writing/reading modules. It is more stable than the usual brittle transducers using (I).