Adaptive video processor
First Claim
1. An adaptive video processor for use with a pattern recognition system comprising:
- video camera means for generating a video signal representative of an area being scanned,circuit means connected to the output of said video camera for generating a substantially constant amplitude output signal,comparing means for generating an output signal whenever said video signal changes positively or negatively with respect to ground,capacitor means interconnecting said circuit means with said comparing means, andcapacitor charging and discharging means selectively controlled by the output of said comparing means for controlling the charging and discharging of said capacitor means to ground as a function of the output signals received from said comparing means.
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Abstract
In a pattern recognition system the video output signal is a signal representative of either black or white. The shading effect of the video camera is minimized by using a high pass filter to accentuate the high frequency components of the signal by partially differentiating the substantially square wave input video signal and feeding forward a sample of the undifferentiated signal thereby retaining some low frequency components of the video signal and thereby minimizing the shading effect of the video camera without increasing detected noise components. Positive and negative-going zero crossings with respect to ground are detected through a capacitive coupled comparator circuit. In the absence of zero crossings the discharge circuit and charge circuit of the capacitor is interrupted thereby maintaining the value of the voltage on the capacitor with respect to ground. Changing the charge and discharge rate of the capacitor reduces the probability that noise on the signal will cause a false zero crossing.
40 Citations
14 Claims
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1. An adaptive video processor for use with a pattern recognition system comprising:
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video camera means for generating a video signal representative of an area being scanned, circuit means connected to the output of said video camera for generating a substantially constant amplitude output signal, comparing means for generating an output signal whenever said video signal changes positively or negatively with respect to ground, capacitor means interconnecting said circuit means with said comparing means, and capacitor charging and discharging means selectively controlled by the output of said comparing means for controlling the charging and discharging of said capacitor means to ground as a function of the output signals received from said comparing means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A circuit for adaptively changing an AC coupled circuit to an effectively DC coupled circuit comprising:
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means for generating an input signal, means for feeding said input signal through a coupling capacitor to a comparator reference to ground, means for charging and discharging said capacitor to ground through a controllable switch whereby said input signal is AC coupled to said comparator with the switch closed, and means responsive to the output of said comparator for opening said switch whereby said input signal is effectively DC coupled to said comparator. - View Dependent Claims (13, 14)
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Specification