GB930611A - Improvements in or relating to electromechanical transducers - Google Patents

Abstract

930,611. Binaural pick-ups and recorders. INDUSTRIES MUSICALES ET ELECTRIQUES PATHE MARCONI. July 3, 1959 [July 3, 1958], No. 22939/59. Class 40 (4). [Also in Group XXXVIII] A pick-up or cutter for stereophonic records comprises two transducers 10, Fig. 2 (one only shown), respectively coupled through two mutually perpendicular coupling members 11, 12 to a cantilever stylus arm 5, whereby in response to movement of a stylus 4 one coupling member 11 transmits only one component of the stylus arm movement and the other coupling member 12 transmits only the component of stylus arm movement perpendicular to said one component. The stylus arm 5 is formed from a tube of lightweight metal and has at one end two mutually perpendicular flattened portions 7, 8. A portion 8<SP>1</SP> is secured between supports 9 mounted in a casing 15, Fig. 3. The transducers 10 are piezoelectric crystals. The coupling members 11, 12 have forked ends 13, 14 into which fits the arm 5. The axes x-x and y-y (Fig. 5) of the coupling members 12, 11 are perpendicular to the major faces of the portions 7, 8 respectively. Limited movement of stylus 4 in the direction of axis y-y produces bending of portion 8 and causes movement of member 12 but not of member 11. Limited movement of the stylus 4 in the direction of axis x-x produces bending of portion 7 and movement of member 11 but not of member 12. The distances apart of the various pieces bear the relationship A<SP>1</SP>B/BD = A<SP>1</SP>C/CE, A<SP>1</SP> (not shown) being the point of intersection of the axis of arm 5 and stylus 4, to balance the two transmission channels. The crystals are secured to covers 18, 19, Figs. 3, 4, and fit in recesses 16, 17 in a casing 15. Terminals 25 are connected to sockets 26 for receiving a connecting plug 27. Reference has been directed by the Comptroller to Specification 871,160.