Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
131 words
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.
Claim 2
Dependent Claim
131 words
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.
Claim 3
Dependent Claim
151 words
An optically readable card according to claim 1, wherein said digital data message is encoded as a succession of bars of equal width disposed side-by-side along two distinct tracks, with data-significant bars representative of binary "1" digits being written in succession on a first one of said tracks, and with data-significant bars representative of binary "0" digits being written on a second one of said tracks which extends parallel to said first track, successive bars on either track, whether they be data-significant bars or dummy bars, being separated from one another by intervening spaces of equal width to said bars or of width equal to an integer multiple thereof, each track being read by a corresponding opto-electronic pick-up during motion in a predetermined direction of the card relative to the pick-ups, each of said pick-ups providing a succession of pulses corresponding to the succession of data-significant bars on the corresponding track.
Claim 4
Dependent Claim
20 words
An optically readable card according to claim 2, wherein said parallel tracks are disposed on opposite sides of the card.
Claim 5
Dependent Claim
22 words
An optically readable card according to claim 1, wherein said card is made of material having a surface which reflects infrared radiation.
Claim 6
Dependent Claim
30 words
An optically readable card according to claim 4, wherein said data-significant marks are printed using an ink of a predetermined visible color, said ink being an absorber of infrared radiation.
Claim 7
Dependent Claim
30 words
An optically readable card according to claim 5, wherein said dummy marks are printed using an ink of the same predetermined visible color, said ink being transparent to infrared radiation.
Claim 8
Dependent Claim
27 words
An optically readable card according to claim 4, wherein said card is made of plastic material which is thick enough to ensure that the card is rigid.
Claim 9
Dependent Claim
15 words
An optically readable card according to claim 4, wherein said card is made of paper.
Claim 10
Dependent Claim
58 words
An optically readable card according to claim 1, wherein said card is made of a material which absorbs infrared radiation, wherein said data-significant marks are printed using an ink of a predetermined visible color which reflects infrared radiation, and wherein said dummy marks are printed using an ink of the same predetermined visible color which absorbs infrared radiation.
Claim 11
Dependent Claim
126 words
An optically readable card according to claim 2, wherein said digital data message is encoded as a sequence of data words (e.g. 8-bit bytes) in such a manner that two successive data-significant bars in the same data word but on different tracks because they are representative of complementary binary digits are located substantially immediately adjacent to each other, and wherein dummy bars are inserted in locations selected from the following possible locations: before the first word in a data message; after the last word in a data message; between two successive words in a data message where the last bit of one word is the same as the first bit of the next word; and between successive occurrences of the same bit within a data word.
Claim 12
Dependent Claim
151 words
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: 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.
Claim 13
Dependent Claim
151 words
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: 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.