Label reader

Claim 1

In a label reading system for reading marks formed of at least two segments the improvement including means for excepting a signal derived from a contrasting gap between two such segments comprising: a capacitor and a charging circuit for charging said capacitor; gating means for discharging said capacitor in response to a signal derived from a gap and enabling said charging circuit to charge said capacitor in response to a signal derived from a segment; a comparator having a first input connected to said capacitor and a second input connected to a reference voltage, said comparator producing a first signal when said capacitor is charged to a voltage which is greater than said reference voltage and a second signal when said capacitor is charged to a voltage which is less than said reference voltage; and a clipping circuit connected to said first input to limit the voltage to which said capacitor can be charged to a value greater than said reference voltage for standardizing the initial level at which discharge of said capacitor begins at the end of each segment, said level being set at a value high enough with respect to said reference voltage to prevent the capacitor voltage from decreasing to said reference voltage during the interval of a gap, whereby the output of said comparator produces a representation of a mark formed of two or more segments excepting interstitial gaps.