Identification card with concealed coding and a simple reader module to decode it
First Claim
1. The combination of an identification card and reading apparatus for said card, said combination comprising:
- (a) a card provided with a concealed code which, while being invisible to the naked eye when viewed in visible light, is readable in transmission using infra-red radiation, said code being characterized by successive digits represented by transparent windows alternating with regions opaque to infra-red radiation, the said windows and opaque regions being arranged along a line parallel to one edge of the card and each window representing a binary digit of the code with one binary digit being represented by wide rectangular windows while the other binary digit is represented by significantly narrower windows;
(b) an optoelectric reader consisting of a single source of infra-red radiation and a single infra-red detector arranged to either side of a card slot to enable the coded card to be read on passage along the slot; and
(c) an electronic system responsive to a signal from said reader and having a first threshold detector arranged to produce a clock signal each time that the reader detects a window in the card and a second threshold detector arranged to produce a second signal to represent a binary one when a second threshold level of output from the electronic reader is passed, the absence of said second signal when a clock signal is detected indicating the presence of a binary ZERO whereby said code windows are self-clocking and the code can be scanned independently of the rate at which said card is moved along the slot.
1 Assignment
0 Petitions
Accused Products
Abstract
An instruction or identification card or badge for use in a time recording system, to authorize admission to restricted locations or for use in credit transactions comprises layers of material that is opaque to visible light but transparent to infra-red radiation. A code that is readable by an optoelectronic reader but is invisible in ordinary light is provided by transparent windows alternating with infra-red opaque regions arranged along a line parallel to one edge of the card, one binary digit being represented by wide rectangular windows and the other binary digit being represented by narrower windows that when read in a badge reader give different peak heights. The code is self-clocking and need occupy only a small portion of the card area.
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Citations
16 Claims
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1. The combination of an identification card and reading apparatus for said card, said combination comprising:
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(a) a card provided with a concealed code which, while being invisible to the naked eye when viewed in visible light, is readable in transmission using infra-red radiation, said code being characterized by successive digits represented by transparent windows alternating with regions opaque to infra-red radiation, the said windows and opaque regions being arranged along a line parallel to one edge of the card and each window representing a binary digit of the code with one binary digit being represented by wide rectangular windows while the other binary digit is represented by significantly narrower windows; (b) an optoelectric reader consisting of a single source of infra-red radiation and a single infra-red detector arranged to either side of a card slot to enable the coded card to be read on passage along the slot; and (c) an electronic system responsive to a signal from said reader and having a first threshold detector arranged to produce a clock signal each time that the reader detects a window in the card and a second threshold detector arranged to produce a second signal to represent a binary one when a second threshold level of output from the electronic reader is passed, the absence of said second signal when a clock signal is detected indicating the presence of a binary ZERO whereby said code windows are self-clocking and the code can be scanned independently of the rate at which said card is moved along the slot. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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Specification