| 摘要 |
PURPOSE:To detect assuredly a mark signal through a simple circuit, by detecting the presence or absence of mark information after extracting a high frequency component contained in a video signal sent from a TV camera. CONSTITUTION:The video signal sent from a TV camera 2 which read a mark label 1, i.e., a subject of detection is supplied to a high band pass filter 4 via an amplifier 3. The low frequency signal component produced by the background contained in the video signal is eliminated through the high band pass filter 4. Then the frequency components at front and rear edges of a mark signal pass selectively the HPF4. The output signal of the HPF4 is supplied to a high band cut-off filter 5, and the noise component in the signal is deleted. The output signal of the HPF4 is supplied to a comparator 7. A slice level controller 6 is provided to control the reference level of the comparator 7. With such a simple circuit, the mark signal can be assuredly detected even though the background has bright and dark areas or the contrast is low between the background and the mark signal. |
