GB1351312A - Apparatus for counting pulses developed by a distance-measuring arrangement - Google Patents

Abstract

1351312 Measuring displacement SOC D'OPTIQUE PRECISION ELECTRONIQUE ET MECANIQUE 2 Dec 1971 [4 Dec 1970] 56012/71 Headings G4D D6Y D6Cl D6L and D1D11 In apparatus for preventing counting errors in a displacement measuring system each pulse from a direction discriminator 4, Fig. 1, representing an increment of displacement of scale 2 relative to heads 1 and occurring on one of two output leads in dependence on the direction of movement, results in either the input 9 or the input 10 of a counter 6 being enabled and also input 8 being enabled so that the signal applied at terminal 7 increments or decrements the counter by one unit. The outputs from the heads 1 may be coded into reflected form before being fed to the discriminator 4. In the embodiment of Fig. 1 the output from discriminator 4 is applied to an exclusive-or gate 11 which results in a monostable 21 giving an output pulse of duration # 1 when one and only one of the outputs of discriminator 4 gives a signal. The monostable output triggers a further monostable 22 triggering another monostable 23 so that after a delay of duration # 2 a signal of duration # 3 is applied to terminal 8 the counter then being incremented or decremented in dependence on which of two AND gates 12, primed by the output of monostable 21, is enabled by the output of a bi-stable circuit 5 connected to the discriminator outputs. In the embodiment of Fig. 2 (not shown) the pulses to be counted are derived from a separate pulse forming circuit (13) connected in parallel with the direction discriminator (4), each pulse triggering a monostable circuit (31) applying a pulse of duration # 1 to the input (7) of the counter (6).