| 摘要 |
PROBLEM TO BE SOLVED: To provide a range finder incorporating a double integral type A/D converter, which can prevent a time lag from being long during measurement of a distance even though an inexpensive high dielectric constant capacitor is used, and which can prevent producing errors in a measured distance. SOLUTION: An output signal from a PSD(position detecting element) 20, caused by light reflected by an object is processed by a measured distance processing circuit 12 which delivers an output analog signal is converted into a degital signal by an A/ D converter in the circuit 12. The measured distance processing circuit 12 and the double integral type A/D converter are controlled by a CPU 10. Further, the circuit 12 and the CPU 10 can be changed over between a first operation mode for performing normal operation and a second operation mode for restraining current consumption. When the CPU is shifted into the first operation mode into the second operation mode, the CPU carries out a series of distance measuring operations in order to avoid erroneously measuring caused by a hysteresis phenomenon such as dielectric absorption. |
