| 摘要 |
PURPOSE:To accurately and easily obtain the just focusing of an image sensor by converting a signal from a photoelectric conversion means into a pulse signal based on a prescribed threshold and counting up the number of leading edges or trailing edges of the pulse signal by a counting means. CONSTITUTION:When image information on a film 1 is read out by an one- dimensional image sensor 6, a signal with an output waveform corresponding to the density of stripes can be obtained. When the signal with the output waveform is applied to a comparator 28 and compared with a threshold voltage S1, a pulse signal is obtained. The pulse signal is supplied to a counter 25, the leading edge of the pulse is counted up, the counted contents are reset every end of the pulse is counted up, the counted contents are reset every end of one main scanning and the data are latched by a latch 26. Simultaneously, the data latched before one main scanning are converted into analog value by a D/A converter 30 and the analog value is sent and indicated to/on a level meter 31. The operator depresses a manual switch 21 and moves a focus adjusting lens vertically so that the vibration of an indicator of the level meter 31 is maximized, so that just focusing can be attained. |
