GB1001146A - Capacitative or inductive coder - Google Patents

Abstract

1,001,146. Electric selective signalling systems. B. LIPPEL. Aug. 14, 1962 [Aug. 16, 1961], No. 31171/62. Heading G4H. A shaft position digitizer comprises a plurality of groups of appropriately shaped rotor plates which co-operate with appropriately shaped stator plates, the latter being arranged so as to be equivalent to "lead and lag " sensing brushes. The embodiments described use capacitative coupling but it is stated that inductive coupling could be used. In a first embodiment, Fig. 1, each group 1, 2, 3 of plates-the rotors A and stators B being shown respectively in Figs. 2, 3 and 4-produces one bit of pure binary output, and each group, except the least significant, has lead and lag segments. A circuit for sensing the positions of the various rotor plates is shown in Fig. 5. In operation a source 74, Fig. 5, applies a pulse to all the rotor plates which pulse is capacitatively coupled, in varying degrees, to the stator plates. The pulse induced in the least significant stator plates 100 is applied to an amplitude discriminator 79 which produces, in accordance with the pulse amplitude, the least significant output bit D1 and which also opens a " lead " or " lag " gate 57, 59, for the next higher denomination, in which the " lead " and " lag " plates 54 are labelled A and B respectively. In a similar way the second output bit D 2 controls the choice of " lead " and " lag " gates for the third bit, and so on. In a second embodiment a complete rotation of the shaft is divided into 100 divisions and a binary-coded decimal output is produced. As a modification of either embodiment it is stated that a high order plate and a low order plate may be combined concentrically, Fig. 12A, to economize on space, especially when the plates are " printed." Specifications 650,913 and 819,252 are referred to.