Patent ID: 6323786
Filing Date: 2001-11-27
Classification: G01P

Abstract:
An absolute-value encoder device comprising:a rotary disc rotating with a shaft;pulse signal forming means for producing first and second pulse signals shifted approximately 90.degree. from each other, each said pulse signal being generated one pulse for each complete revolution of the shaft, based on light passing through a light shut-off portion provided on said rotary disc, wherein there are four angular segments into which angular positions of one revolution of said shaft are divided, each said angular position specified by said first and second pulse signals;clock generating means for generating a clock pulse signal; androtation quantity counting means which counts, based on said clock pulse signal, when said first pulse signal changes its logic level while said second pulse signal is in a predetermined logic level, and holds the present value of the number of revolutions of said shaft;wherein when either of said two pulse signals changes its logic level, said clock generating means changes the frequency of said clock pulse signal to a higher frequency.