GB855018A - Improvements in or relating to displacement transducers - Google Patents

Abstract

855,018. Displacement transducers. SHORT BROS. & HARLAND Ltd. April 1, 1959 [April 11, 1958], No. 11609/58. Class 40 (1). A displacement transducer comprises a differential transformer provided with two subsidiary magnetic flux paths of adjustable reluctance in order that the flux in the main flux paths of the transducer may be varied to provide zero setting or sensitivity adjustment. Fig. 1 shows an E-type differential transformer provided with subsidiary flux paths O 1 , O 2 . Fig. 2a shows a modified armature to replace A in Fig. 1 to respond to rotational movement. Fig. 5 shows an alternative form of rotational transducer while Fig. 6 shows a further alternative form in which a core A of semicircular cross - section rotates inside coil SW between U-shaped cores carrying coils PW 1 and PW 2 . In these embodiments, Figs. 5 and 6, the primary winding is split and the secondary winding therefore has no induced E.M.F. when the transformer is in its balanced condition, in contrast to systems using a split secondary where equal E.M.F.'s are induced in the secondary winding which cancel out in the external circuitry and which therefore require components of a higher rating in the external circuit. Fig. 2 shows a differential transformer connected to a transistor demodulator circuit whereby a unidirectional output is derived from the A.C. input, reference voltages for the demodulator being derived from coils C 1 , D 1 , and C 2 , D 2 , wound on the same limbs as the primary winding PW 1 and PW 2 . Also described is a further alternative system of windings in which the primary winding is wound on the centre limb of an E-type transformer and the secondary is wound in 4 parts, each half of the winding having a section on each of the outer limbs of the core so that in balance the voltages induced cancel in the secondary winding rather than the external circuitry.