| 摘要 |
PURPOSE:To easily and accurately match the focus of an image pickup device by finding the conditions of focusing by comparing the numbers of picture elements in respective scanning periods, and lighting a display element when the condition of the smallest number of picture elements is satisfied. CONSTITUTION:A count-up counter 8 counts up pulses in one cycle of the image picture number signal CT of the board part between an object image and its background. When the counted value X2 is smaller than a numeral X1 which is already latched by a latch circuit 9, numely, when X1 > X2, a flip-flop 13 for display is connected to a count-down counter 11 for display whose smaller value of the picture element is latched by the latch circuit 9 in every scanning cycle; when its output 22 and a scanning end signal ED satisfy a NAD condition at a NAND gate 17, a lighting signal 24 is inputted to a pulse generator 9, so that the display element 21 lights throughout the output period of one-shot pulses 26. |
