Method and device for reading coded information in the form of intervals of predetermined sizes

A method of recognizing an item of information defined by a first plurality m of different intervals between consecutive pulses of a primary pulsed signal, said method comprising:

• generating a second plurality n of separate pulsed signals the pulses of which are differently delayed with respect to corresponding pulses of the primary pulsed signal by delay intevals e;
• comparing the pulsed signals of the second plurality n to produce an output signal representing the item of information, the delay interval e between a first and second signal of the second plurality being selected and the comparison being such that a first interval a of the first plurality m is identified when a leading edge of a pulse of the second signal occurs during a pulse of the first signal, a second interval b of the first plurality m is identified when a trailing edge of a pulse of the second signal occurs during a pulse of the first signal, and an interval of the first plurality m which is different from the first and second intervals a and b is identified when neither a leading nor a trailing edge of a pulse of the second signal occurs during a pulse of the first signal.

A device for reading an item of information defined by a plurality of different intervals between consecutive elements on a data carrier, said device comprising:

• first and second element detectors arranged for motion relative to the elements on the data carrier, generating responses to the elements, and spaced from each other by a distance e such that the responses to each element generated by said second element detector have a delay corresponding to the distance e with respect to the responses generated by said first element detector;
• and
• means for comparing the responses of said first and second element detectors to produce an output signal representing the item of information, the distance e being selected and the comparison being such that a first interval a is identified when the beginning of a response by said second element detector occurs during a response by said first element detector, and a second interval b is identified when the end of a response by said first element detector occurs during a response by said first element detector.