| 摘要 |
PURPOSE:To obtain accurate distance information without performing feedback control over a projecting means by increasing or decreasing the amplification degrees to two photodetection outputs by projection gradually, and latching the difference calculation output obtained by subtracting the sum of the outputs by a specific value or photodetection outputs as the distance information. CONSTITUTION:When a power source switch 2 is turned on through a shutter release button, a PUC signal is generated and the voltage V2 to one-side input terminals of multiplying circuits 26 and 27 rises. The output light of a light emitting diode 10 is projected upon a body 66 whose distance is to be measured and its reflected light is made incident to the photodetection surface 20 of a PSD19, whose output is inputted to V1 terminals of the multiplying circuits 26 and 27 and multiplied by the input V2; and an adder outputs a sum signal (VA+VB) and a subtractor outputs a difference signal (VA- VB) respectively. The voltage of a signal corresponding to the sum signal (VA+VB) of the adder is compared by a comparator 57 with the voltage of a variable resistance 58 and its output is latched by a latch circuit 55 to measure the distance. The PSD19 generates a photocurrent when light is incident to the photodetection surface 20 and a current outputted from an electrode is a function of photodetection points, so that the distance measurement is taken by the photodetection points. |
