Digital strain measurement technique

摘要

An electrical circuit provides a digital representation of strain and uses electrical resistance strain gauges 2, 4 arranged in a Wheatstone bridge 1. The bridge unbalance output is integrated at 16 and compared with a reference at 19. When the reference is exceeded, flip-flop 23 changes state and closes analogue CMOS switches 10, 11 to connect resistors 8, 9 in parallel with bridge resistors 3, 5. The length of time the resistors are switched in parallel with the bridge is proportional to the magnitude of the applied strain and this time is determined by counting clock pulses. The result is displayed as a digital representation of the strain applied. IMAGE