| 摘要 |
PURPOSE:To measure a distance at multi-stages by using a triangular distance measuring type distance measuring circuit of current difference comparing type which eliminate the necessity of a logarithmic compression stage. CONSTITUTION:A light projecting part 1 emits a light beam which is then reflected by an object to be measured for a distance, and the reflected light beam is received by light receiving cells S1, S2 from which currents run. An amplifier 28 calculates a difference between the currents, and a comparator 34 determines the sign of the current difference. The current running through the cell S2 is weighed by transistors 19, 22, 23, and then runs through a subtracting point in the amplifier 28. Accordingly, by carrying out comparison with the use of the comparator 34 while successively selecting the transistors 19, 22, 23, multi-stage distance measurement can be made while the reference point is shifted. Meanwhile, a photocurrent in one of the cell is compared with a reference level by the comparator 34, indefinite distance determination can be made. |
