| 摘要 |
<p>PURPOSE:To detect the different light receiving levels even in case to output a constant level of light receiving signal by a light receiving unit composed of a single chip from a light receiving element to a comparison circuit. CONSTITUTION:A light projecting member 1 projects the light in a specific cycle, and outputs plural phase beams increasing the light projecting amount gradually in one round projecting operation. When a light receiving unit 9 receives the pulse beam by a light receiving element 10, the pulse beam is converted into an electric signal, integrated in an integration circuit 12 through an amplifier circuit 11, and when the integrated value exceeds a standard value, a light receiving signal of 'H' level is output from a comparison circuit 13. A deciding circuit 14 outputs a detecting signal when the setting time to detect the light receiving condition is reached, by the first discriminating circuit 15, according to the receiving signal from the light receiving unit 9, and outputs a stable operation signal when a setting time to detect the stable operation condition is reached. Consequently, a detection corresponding to the different light receiving amount can be carried out while preventing an error detection owing to a single round of external disturbance light.</p> |
