| 摘要 |
<p>PURPOSE:To make the dead area in detection absolutely zero by partially varying the sensitivity of the received light of each electrode, and arranging the electrodes so that the sensitivity distributions are arranged in the reverse directions. CONSTITUTION:The thicknesses of regions E1 and E2, which are divided into two parts, in transmitting electrodes 2 and 3 having the equal light receiving area, are made different. The electrodes have light receiving sensitivities S1 and S2 (S1>S2) having the partially different sensitivities. The electrodes 2 and 3 are arranged on the surface of a pyroelectric ray material 1 so that the sensitivity distributions are arranged in the reverse directions. Thus, the electrodes 2 and 3 have the region E1 of the high sensitivity S1 and the region E2 of the low sensitivity S2. Since the light receiving area (E1+E2) is equal, however, the output difference is not generated in common-mode noises such as solar light, which are cast into the electrodes 2 and 3 at the same time. The noises are offset and can be removed. Since the directions of the regions E1 and E2 are reverse, the difference is generated in the amounts of the transmitted lights of the incident infrared rays based on the difference between the sensitivities S1 and S2 of the light receiving parts even if a moving body approaches from, any direction, e.g. the direction (a) or the reverse direction. The difference is detected as the output difference. Therefore, the dead area in detection can be made zero.</p> |
