| 摘要 |
PURPOSE:To normally operate a sense amplifier even in the condition of much disturbing light without making the equipment large sized by differentiating the output signal of a pulse modulation light receiving means by a differentiating means and integrating this signal by an integrating means thereafter and shaping the waveform of the integral signal by a waveform shaping means to obtain an output signal. CONSTITUTION:When the pulse modulation light from a light projecting element 14 and a disturbing light 16 are made incident on a light receiving element 15, an electric signal corresponding to this incident light is supplied to a pulse modulation light receiving circuit 17, and the output signal of this circuit 17 has a waveform resulting from superposition of the disturbing light 16 on the pulse modulation light. This waveform is differentiated by a differentiating circuit 18 to obtain a waveform consisting of only signal components of the pulse modulation light and the disturbing light 16. This differential signal is integrated by an integrating circuit 19 to obtain an integral waveform, and this integral waveform is shaped by a Schmitt trigger circuit 20 to remove the signal component of the disturbing light 16, and the output waveform consisting of only the signal component of the pulse modulation light is obtained. Thus, a light shielding means is unnecessary even in the condition of much disturbing light and the equipment is prevented from being made large-sized. |
