Importance

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Abstract

In an optical detection system for detecting a feature located at a predetermined lateral position on a banknote, for example, the banknote is moved along a flow path and a series of light receivers are arranged transversely across that portion of the flow path which the feature is expected to occupy, so that different ones of the light receivers will respond to the feature in the banknote depending on the lateral offset of the banknote at that portion of the flow path. The margins of the note are utilized in the detection system to gate the said light receivers so that for any position of lateral offset of the banknote only that light receiver which responds to the said feature of the banknote will produce an effective output signal. In the embodiment of FIG. 1, two sets of fibre optics are used to effect this gating, one set having its first ends (S1 to S5) opposite a light source at one margin of the sheet and its other ends (F1 to F5) adjacent the above mentioned light receivers (F1' to F5'). The said light receivers are constituted by first ends of the second set of fibre optics, the other ends (D1 to D5) of which provide light output for a detector at the other margins of the notes. An electronic gating system is also disclosed (FIG. 2).

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First Claim