| 摘要 |
PURPOSE:To accurately guide a flight body, by providing an area operation circuit for always measuring the area of a target and a judge circuit. CONSTITUTION:An infrared ray receiving element 3 converts infrared rays scanned by a scanning optical system 1 to an electric signal and a filter circuit 5 applies filtering processing to the output of the infrared ray receiving element 3. A multiplexer 27 selects the output of the circuit 3 and the output of the infrared ray receiving element 3. A threshold value setting circuit 9 receives the digital video data being the output of an A/D converter circuit 7 to determine a threshold value and a binarization circuit 11 receives said threshold value to binarize the digital video data. A center-of-gravity operation circuit 13 receives the output of the circuit 11 and calculates the center of gravity of a target region to output a guide signal. An area operation circuit 23 receives binary video data 12 to calculate the area of the target area and a judge circuit 25 compares area data 24 with the determined threshold value and, when the data 24 is larger than the determined threshold value, a changeover signal 26 is made significant and an analogue video signal 4 is supplied to the A/D converter circuit 7.
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