| 摘要 |
<p>A fully automatic exposure control system is desired for providing either a shortened or an extended maximum exposure interval time out period dependent upon the distance between the camera and subject either directly by sonic ranging or indirectly by sampled reflected light. An automatic exposure control system is disclosed wherein a sonic rangefinder (132) and counter (146) sets a flip-flop (166) if the subject distance is far beyond the effective flash range. A logic circuit (168, 170, 172) routes a shortened or extended maximum exposure time out signal from counter (174) if the light integrating circuit (72) has not reached a certain level (88) to terminate exposure. Alternatively the maximum exposure interval time is lengthened if logic circuit (90) detects light integrating circuit (72) has not reached a certain level (84) when a pulse (114) is generated overlapping the illumination period. </p> |
