GB1181536A - Improvements in or relating to Apparatus for Measuring Length. - Google Patents

Abstract

1,181,536. Length measuring systems. GERHARDT MESSMASCHINENBAU. 5 July, 1967, No. 31001/67. Heading G4H. In apparatus for measuring length by generating a voltage representing the length and comparing it in a comparator 3 with a variable reference voltage derived from the count in a counter 14, 15 the comparator 3 determines which of two pulse trains 6, 7 are fed to the counter 14, 15 (depending on the sense of the difference between the reference voltage and the measurement voltage) so that the counter 14, 15 counts in the direction which reduces the difference. In the embodiment described a measurement sensor 2 is fed with A.C. current from a generator 1 to supply a measurement voltage to comparator 3. The voltage from generator 1 is also fed to a pulse shaper 5 which generates positive and negative square wave pulse-trains 6, 7. The comparator 3 controls a switch 10-either a three position switch or a full wave rectifierso that one of the pulse trains is fed to the counter, the count being stopped when the inputs to the comparator are equal. The two decade counter 14, 15 is connected to transformers 16, 17, a number of tappings on the transformers, in accordance with the number of pulses counted, being brought in to step the reference voltage. The count is displayed on indicators 18, 19. To measure the maximum or minimum of a series of inputs, switch 8 or switch 9 may be opened so that the counter can only be incremented in one direction.