GB709528A - A magnetostrictive and electromechanical transducer device - Google Patents

Abstract

709,528. Piezo-electric and magneto-strictive instruments. CLEVITE CORPORATION. Oct. 30, 1951 [Jan, 24 1951], No. 25332/51. Class 40 (4) [Also in Groups XXXVI, XXXVIII and XL (c)] A piezo-electric element and a magnetostrictive element are secured together so that either element may be used to exert a mechanical control over the other. The mechanical strain in the controlled element controls the electrical characteristic of a circuit associated with the element. Both elements may be electrically controlled to produce mechanical vibration in the device. As shown in Fig. 1, a plate 10 is of Rochelle salt or of barium titanate is secured between a nickel plate 11 and an electrode 12. With the switches 17, 22 as shown, signals from a source 16 control the piezo-electric element 10. The magnetostrictive element 11 is driven by the piezoelectric element 10 and produces flux changes in a coil 21 which feeds a signal reproducer 25. A D.C. bias is supplied from a source 23 and may be cut out by a switch 30. By means of the switches 17, 22 either element may be connected to a source of signals and the other element to a signal reproducer. Both elements may be driven by signals simultanously to vibrate the device either as an expander or as a bender. The magneto-strictive element may be biased electromagnetically as shown or by a permanent magnet 32, Fig. 2 or by residual magnetism. An element of barium titanate is prepolarized in known manner by a high D.C. voltage. The electrode 12 may consist of a second magneto-strictive element. Two piezo-electric elements 10 may be combined with three magneto-strictive elements as shown in Fig. 4., The elements of any of these devices may be formed as closed loops. If a small gap 44 is left in the magnetostrictive element 41, the cylindrical device shown in Fig. 5 may be used as a recording or reproducing head (see Group XXXVIII) or as a device for measuring magnetic fields (see Group XXVI). The magneto-strictive elements 11 are used to couple coils 75, 76 in the anode circuit and the grid circuit of an oscillator valve 70, Fig. 11. The coupling is controlled by the bias potential applied from a source 77 to the piezo-electric element 10. Fig. 12 shows the device used as a variable coupling between an A.C. source 80 and a voltmeter 85. The coupling is controlled by an adjustable source 82 of D.C. bias and a biasing coil 83.' The elements of the device may be cemented together. Nickel may be electroplated on some piezo-electric elements and may be soldered or fired to barium titanate. The device may be used instead of quartz to control the frequency of oscillatory circuits (see Group XL (c)).