Data coding systems

Claim 2

A data code reader system for reading data represented in the form of a number of pairs of optically recognisable elements arranged in line, the elements of a pair having different relative reflectivity shade or colour, the significance of a pair (i.e., mark or space) being determined by the relative width of the elements of a pair, comprising light sensitive code reading means for producing a video waveform as data represented by said elements is scanned, the video waveform being utilised to gate pulses from a clock pulse generator to counter means, pulses counted during scanning of one element of a pair being compared with the number of pulses counted during scanning of the other element of the pair to provide an indication of the significance of data represented by that pair, the counter means being zeroed consequent upon the detection of a transmission from a light to a dark element and arranged to count up clock pulses during a dark element and triggered consequent upon the transition from a dark to a light element of a pair to count down clock pulses towards zero, the count state just before the next successive zeroing operation being indicative of the significance of data represented by the elements of a pair.

Claim 3

A data code reading system for reading data represented in the form of a number of pairs of optically recognisable elements arranged in line, the elements of a pair having different relative reflectivity shade or colour, the significance of a pair (i.e., mark or space) being determined by the relative width of the elements of a pair, comprising light sensitive code reading means for producing a video waveform as data represented by said elements is scanned, the video waveform being utilised to gate pulses from a clock pulse generator to counter means, pulses counted during scanning of one element of a pair being compared with the number of pulses counted during scanning of the other element of the pair to provide an indication of the significance of data represented by that pair, wherein the counter is zeroed consequent upon the detection of a transition from a dark to a light element of a pair and thereafter arranged to count clock pulses from the clock pulse generator until the detection of a transition from a light to a dark element, whereupon the counter is arranged to count down towards zero for a period during which the light element is scanned, the count state being interrogated just before the counter is zeroed consequent upon the detection of the next transition from a dark to a light element, the interrogated count state being indicative of the significance of data represented by the elements of the pair.

Claim 4

A data code reading system for reading data represented in the form of a number of pairs of optically recognisable elements arranged in line, the elements of a pair having different relative reflectivity shade or colour, the significance of a pair (i.e., mark or space) being determined by the relative width of the elements of a pair, comprising light sensitive code reading means for producing a video waveform as data represented by said elements is scanned, the video waveform being utilised to gate pulses from a clock pulse generator to counter means, pulses counted during scanning of one element of a pair being compared with the number of pulses counted during scanning of the other element of the pair to provide an indication of the significance of data represented by that pair, wherein the counter is zeroed consequent upon the detection of a transition from a dark to a light element of a pair and thereafter arranged to count clock pulses from the clock pulse generator until the detection of a transition from a light to a dark element, whereupon the counter is arranged to count down towards zero for a period during which the light element is scanned, the count state being interrogated just before the counter is zeroed consequent upon the detection of the next transition from a dark to a light element, the interrogated count state being indicative of the significance of data represented by the elements of the pair.