| 摘要 |
PURPOSE:To obtain the accurate focus information on an image of low contrast, by transmitting the output signals delivered from the adjacent photodetectors to a detection part via the same transmission line. CONSTITUTION:The output signals of a counter 32 increase one by one and then written into an RAM28 when the analog signal in accordance with the output signal is coincident with the output signal of a photodetector. Changeover switches 14 and 24 are switched in coupling to each other. As a result, the output signal of a photodetector 10-i is written into a storage area 28-iA in the 1st state, and the output signal of a photodetector 30-j is written into a storage area 28-(j+1)B in the 2nd state. In this case, the difference of data between the areas 28-iA and 28-iB is identical with the difference of output signals of the adjacent photodetectors. Thus the effect of the threshold voltage and the offset voltage of each element within a transmission line 12 can be eliminated. In such way, the accurate focus information can be obtained even for an image of low contrast. |
