| 摘要 |
<p>An automatic continuous focus system having range sensing means for providing a time varying first signal having first and second states, the last transition of the first signal from the first to the second state being indicative of a position of proper focus; a signal source; signal storage means; first switch means connected to said range sensing means and operable in accordance with the first signal to connect said signal source to said signal storage means upon the occurrence of the last transition whereby said signal storage means thereafter stores a second signal derived from said signal source and of magnitude which varies with the time of occurrence of the last transition; and means connecting the signal storage means to the drive means to cause the drive means to move the lens means toward the position of proper focus at a rate which depends upon the magnitude of the second signal.</p> |
