| 摘要 |
PURPOSE:To obtain easily by one chip a photoelectric converting element which is capable of detecting a reflected light from an object which has a high S/N and a wide external light dynamic range, and can be used easily, by providing two photoelectric accumulating parts and a difference accumulating part for accumulating a difference of its accumulation quantity, on a single photoelectric converting part. CONSTITUTION:A charge of a photoelectric converting part 7 is accumulated in accumulating parts 11, 12 by a gate 8 which is opened at the time of projection, and a gate 10 which is opened by an inverting signal by an invertor 9 at the time of non-projection. A difference of the charge (voltage) accumulated in both accumulating parts 11, 12 is a reflected light component by a projection being a signal, but in case when an external light component is large, it sometimes occurs that the accumulating part is saturated before a sufficient difference output is obtained. Therefore, a reference voltage by resistances 15, 16 and each accumulating voltage are compared by comparators 13, 14, it is detected by one OR gate output that one accumulating part has reached a prescribed level, a monostable multivibrator 18 is started by its rise signal, and a signal of high of a prescribed width is outputted to a line 19 from Q. |
