| 摘要 |
PURPOSE:To remove various error detections and automatically detect the precise focusing state by obtaining respective time series luminance signals from two systems of photo detector rows, digitally converting the same to binary coded signals and detecting the maximum value of the coincidence information of both optical images. CONSTITUTION:A first optical system 20 which fixes an optical axis 30 to the target 2 and a second optical system 22 in which an optical axis 32 is movable are provided and a standard image 34 and a reference image 36 are formed respectively on the line sensors 24 linearly arrayed within the same plane 26 by both optical systems. From the image plane illuminance distrubution thereof, the control signal for focus adjustment is obtained. At this time, high speed clock pulses are supplied to the line sensors 24 to have the video signal corresponding to the brightness of the images outputted. The peak value thereof is then detected with a peak holding detection circuit 116 and is converted to a binary coded signal by a comparator 64. This digital signal is processed in the order of operation modes by sequence-controlling a series of data-processing means to detect the maximum value of the coincidence information of both optical images. This value is made the focused position. Thereby, the focus detection of high reliability may be performed. |
