| 摘要 |
PURPOSE:To save the labor and time for a focus adjustment and to eliminate an error due to individual differences by scanning the same object successively, by comparing levels of two successive video signals with each other and by making the focus adjustment with the comparison output. CONSTITUTION:Firstly, vertical scan control part 5 sets a vertical scanning mirror in the center of an image, and infrared rays IR from an object are incident to infrared-ray detector 3 via a condenser mirror and converted into a video signal. This video signal is inputted to focus adjustment control part 6 and its maximum signal level near the center of the signal waveform is extracted by circuit 61 and stored in memory 63 temporarily. In this state, the condenser mirror is moved slightly and a maximum signal level is extracted from the video signal at that time and compared by comparing circuit 62 with the stored signal level in memory 63. Then, the condenser mirror is shifted slightly in position toward focus matching according to the comparison result to make a focus adjustment. |
