| 摘要 |
PURPOSE:To execute distance measuring operation with high accuracy, and also to eliminate the waste of a distance measuring operation time by providing an offset correcting circuit for suppressing an integral output of the time to a prescribed value or below, on an integration circuit when the light for distance measurement is not emitted yet. CONSTITUTION:An offset correcting logic 321 generates correcting signals 302a, 302b from three signals of output LL, HH and AB of a comparing circuit constituted of 104-107. The correcting signals 302a, 302b are applied through fixed resistances 309a, b to inputs of operational amplifiers 304a, b of a high input impedance. A variation of output voltages of 304a, b, namely, correcting voltages 303a, b is determined by the fixed resistances 309a, b, capacitors 306a, b, and an applied voltage and an applied time of the correcting signals 302a, b. Accordingly, by controlling the polarity of the applied voltage and the applied time, this output voltage, namely, correcting voltages 303a, b can be set optionally. The correcting voltages 303a, b are applied to inputs of integration circuits 103a, b, namely negative input terminals of operational amplifiers 208a, b through fixed resistances 305a, b, and a correcting current proportional to the voltage is made to flow. |
