| 摘要 |
PURPOSE:To improve distance measuring accuracy with simple constitution by N(=2<n>)-ary coding an integral time difference of a couple of sensing elements. CONSTITUTION:Outputs from a couple of the sensing elements 1a and 1b are inputted to an (n) bit counter part 2a via an exclusive OR gate 4 and an AND gate 7a. When a reset signal is given, the elements 1a and 1b start to integrate photodetector output. Integration values of the elements 1a and 1b attain prescribed values in times t2 and t1 respectively. The gate 4 detects a period of time when the outputs Si and Si+1 are discorded. Since the gate 7a passes a count clock phi1 from the outside by the period of time, the counter part 2a performs count. At this time, a select signal Se is given. Further, when an interval between the times t1 and t2 is too long and outputs Q0-Qn-1 of the counter part 2a are all made high levels (H), the outputs are stopped at (H) all. In this way, the integration time difference between the elements 1a and 1b can be obtained as data with an (n) bit mark. |
