| 摘要 |
PURPOSE:To preclude misrecognition without any of the influence of a pattern du as irregular reflection, etc., of light in a pellet by deciding the inside and outside of the pellet with the differentiated value of an input video signal. CONSTITUTION:The input video signal 14 is lowered in its level by a constant quantity through a shifter 5 and supplied to an analog switch 13. The signal 14 is made into an impulsive signal 16 by a differentiator 6 and the signal 16 becomes a positive pulse at a corresponding change point 18 at the time of the movement of a scanning point on a picked-up image from the outside of the pellet to the inside, is not made into a pulse in a pattern area 19 corresponding to the pellet inside, and becomes a negative pulse at a corresponding change point 20 at the time of the movement of the scanning point from the pellet inside to the pellet outside. Those positive and negative pulses are passed through a filter circuit and the output of an FF 13 is held at 'H' and 'L'. The switch 13 sends either of a fixed slice level voltage 4 and the output of the shifter 5 to a comparator 3 as a slice level signal 15 according to the output of the FF 12, so that the signal 14 is converted into a binarizing signal 17A.
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