Optically readable card carrying digital data, and an access control system using said card
First Claim
1. An optically readable card for carrying a digital data message, comprising:
- at least one succession of marks and spaces having respective different optical properties, the marks and spaces being detectable by an opto-electronic pick-up means, the pick-up means including a source of light radiation and a detector therefor;
wherein the succession of marks includes genuine data-significant marks having a first optical spectral response to light emitted by the source of light radiation, the genuine data-significant marks being interspersed with dummy or decoy marks having the same appearance visually and photographically as the genuine data-significant marks, the dummy or decoy marks responding to light emitted by the source of light radiation with a second optical spectral response, the second response being analogous to the response of the spaces to the light radiation.
1 Assignment
0 Petitions
Accused Products
Abstract
The card is particularly intended to give a card-holder access to a service such as pay-TV (broadcast or cable), but in principle could be adapted to any lock-and-key type of system, e.g. credit cards, cards giving access to computer terminals or rooms, etc. The data is encoded on the card in the form of data-significant marks and spaces (2, 3). For example, the marks (2) may be distributed along two parallel tracks with marks in one track representing "1" bits and marks in the other track representing "0" bits. Dummy marks (20, 21, 30, 31, 32, 33) are also made on the card. The dummy marks have the same appearance to the human eye and to photographic and photocopying equipment as the data-significant marks. However, they are printed using inks having a different response in an invisible part of the spectrum, so that card reading equipment can be made to treat dummy marks differently from the way it treats data-significant marks. This makes the cards difficult to fake using commonly available equipment.
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Citations
11 Claims
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1. An optically readable card for carrying a digital data message, comprising:
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at least one succession of marks and spaces having respective different optical properties, the marks and spaces being detectable by an opto-electronic pick-up means, the pick-up means including a source of light radiation and a detector therefor; wherein the succession of marks includes genuine data-significant marks having a first optical spectral response to light emitted by the source of light radiation, the genuine data-significant marks being interspersed with dummy or decoy marks having the same appearance visually and photographically as the genuine data-significant marks, the dummy or decoy marks responding to light emitted by the source of light radiation with a second optical spectral response, the second response being analogous to the response of the spaces to the light radiation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. In an access control system using optically readable cards for giving card-holders access to a service, each of the cards including at least one succession of marks and spaces having respective different optical properties, and wherein the succession of marks includes genuine data-significant marks, the genuine data-significant marks being interspersed with dummy marks having the same appearance visually and photographically as the genuine data-significant marks, the access control system comprising:
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an optical reader having two pick-ups, each pick-up including a source of light radiation of predetermined spectrum for giving a first optical response when inspecting the genuine data-significant marks and for giving a second optical response when inspecting spaces or dummy marks; and a detector of the light radiation for detecting the optical responses, the detector being insensitive to that portion of the visible light spectrum which is absent from the predetermined spectrum; whereby the dummy marks are treated as spaces.
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Specification