| 摘要 |
PURPOSE:To enable a range finder to have multiple functions with simple circuit configuration without using any expensive IC for auto-focusing by amplifying and smoothing one of two current signals outputted from a position detecting means and calculating the distance to an object from the difference between the amplified and smoothed output of the current signal and the amplified output of the other current signal. CONSTITUTION:An IRED 10 projects pulsed distance measuring light upon an object 13 and an optical position detecting element (PSD) 1 receives reflected light from the object 13 and outputs two current signals depending upon the incident position of the reflected light. The two current signals are respectively amplified by means of amplifiers 2 and 3 and the output of the amplifier 2 is smoothed through a low-pass filter 4. A computing element 6 computes the differences between the outputs of the amplifiers 2 and 3 and between the outputs of the filter 4 and amplifier 3. A CPU 8 calculates the distance to the object 13 based on the subtracted results. |
