GB1131466A - Position digitizer apparatus - Google Patents

Abstract

1,131,466. Selective signalling. W. J. MILAN-KAMSKI. 20 Jan., 1966, No. 2675/66. Heading G4H. In a shaft position digitizer, Fig. 1, an outer track comprising a pattern of magnetizable material on a disc of non-magnetizable material is sensed by two groups of series connected heads 15, 16 so arranged as to produce quadrature outputs, Fig. 5, which pass through 32 complete cycles for one revolution of the disc, two inner tracks are each sensed by an arcuate head 17, 18 also arranged to produce quadrature outputs but passing through one complete cycle for one revolution of the disc, each pair of quadrature signals is digitized to seven bits by conventional self-balancing techniques using potentials, shown dotted on Fig. 5, produced by additional windings on the heads as reference potentials, and the resulting two 7- bit numbers, which have an overlap of two bits, are combined, the bits derived from the outer track being used to correct the bits derived from the inner track, to produce a 12-bit representation of the position of the disc. Each head (Figs. 2a and 2b, not shown) comprises an E-shaped core having an input winding on the centre limb and three output windings on each of the outer limbs, two pairs of these windings being connected in series adding to provide the two reference potentials and the remaining two windings (one on each outer limb) being connected in series-opposition to provide the data output signal which varies linearly, as shown in Fig. 5, with the disc position.