| 摘要 |
<p>PURPOSE:To provide a human body sensor in which light is projected at two different light quantity levels alternately from light projecting elements, variation of projecting light quantity level and receiving light quantity level are determined, behavioral conditions of an object to be searched are detected, and then positive control procedures are taken in response thereto. CONSTITUTION:High and low level pulse signal generating circuits 21, 22 at a light projecting section 2 produce a signal 23a having a signal level composed of a code sequence of alternating magnitudes and the signal 23a is fed to a transistor 24b in a light projecting circuit 24 and a comparison reference signal input terminal 4a of a position deciding means 4. The light projecting circuit 24 projects infrared rays having a level determined based on a signal 23a to be modulated being applied to the transistor 24b. The infrared rays impinge on a light receiving element 31 and then amplified 32, detected 35, and shaped 36 to produce a signal having predetermined level. The position deciding means 4 compares the signal 23a fed to the terminal 4a with a receiving light quantity deciding output signal 3a fed to a decision signal input terminal 4b and decides a position according to a reference when the signal 3a is in synchronism with the signal 23a corresponding to a light projection signal.</p> |
