| 摘要 |
PURPOSE:To correctly measure the distance to an object by providing a circuit which casts light to the object from a light emitting element, photoelectrically converts the reflecting light from the object by a photodetecting element, thereby to detect the distance to the object based on the photoelectrically converted signals, and first to third control circuits. CONSTITUTION:When a rectangular wave impressed to a control terminal of a transistor 15 is at the high level, a constant current flowing in a transistor 17 is an ON current for a light emitting element 11. Accordingly, the element 11 emits light and a transistor 16 is turned OFF. On the other hand, when the rectangular wave impressed to the transistor 15 is in the low level, the transistor 15 is turned OFF and the constant current flowing in true transistor 17 runs to the transistor 16. Therefore, the current supplied from a power source 18 is always constant. In this manner, the light cast from the element 11 is modulated and radiated to the object 12. The reflecting light from the object, 12 is photoelectrically converted by a photodetecting element 13. A detecting circuit 14 detects the distance to the object 12 on the basis of tone photoelectrically converted signals from the element 13. |
