Displacement measuring device utilizing an incremental code

Claim 1

A device for measuring displacement comprising a coding member carried by an object to be measured and having a coding section capable of causing sensing elements to generate signals which can be discriminated as "0" and "1", and sensing means arranged to sense the coding section of the coding member and adapted to generate detection signals in response to displacement of the coding member, so that the detection signals are counted for measurement of displacement, the sensing means including first and second sensing elements arranged to generate first and second detection signals with a phase difference of 90° therebetween; first and second rectangular wave-converting circuits for receiving respectively the first and second detection signals to generate respectively first and second rectangular wave signals; a clock pulse generator for generating clock pulses of a frequency higher than the frequency of the first and second detection signals; an edge detector for receiving the clock pulses and at least one of the first and second rectangular wave signals to output, as output pulses, clock pulses coinciding with at least one of the leading and trailing edges of the first and second rectangular wave signals; a speed detecting device which has a speed detector including a counter adapted to receive the output of the edge detector and be cleared every predetermined period of time, a comparator adapted to receive a counted value from the counter and a set value from a speed setting unit for outputting a signal when the counted value has exceeded a set value and a display unit adapted to make a display when the comparator has outputted the signal; the counter of the speed detector being adapted to count the output pulses from the edge detector and be cleared by a frequency-divided pulses obtained by frequency-dividing the clock pulses from the clock pulse generator.

Claim 2

A device for measuring displacement comprising a coding member carried by an object to be measured and having a coding section capable of causing sensing elements to generate signals which can be discriminated as "0" and "1", and sensing means arranged to sense the coding section of the coding member and adapted to generate detection signals in response to displacement of the coding member, so that the detection signals are counted for measurement of displacement, the sensing means including first and second sensing elements arranged to generate first and second detection signals with a phase difference of 90° therebetween; first and second rectangular wave-converting circuits for receiving respectively the first and second detection signals to generate respectively first and second rectangular wave signals; a clock pulse generator for generating clock pulses of a frequency higher than the frequency of the first and second detection signals; an edge detector for receiving the clock pulses and at least one of the first and second rectangular wave signals to output, as output pulses, clock pulses coinciding with at least one of the leading and trailing edges of the first and second rectangular wave signals; a speed detecting device which has a speed detector including a counter adapted to receive the output of the edge detector and be cleared every predetermined period of time, a comparator adapted to receive a counted value from the counter and a set value from a speed setting unit for outputting a signal when the counted value has exceeded a set value and a display unit adapted to make a display when the comparator has outputted the signal; the counter of the speed detector being adapted to count the output pulses from the edge detector and be cleared by a frequency-divided pulses obtained by frequency-dividing the clock pulses from the clock pulse generator.