Communications: electrical – Continuously variable indicating – With meter reading
Patent
1988-06-28
1989-09-05
Yusko, Donald J.
Communications: electrical
Continuously variable indicating
With meter reading
340825340, 340825540, 361172, 235439, H04Q 900, E05B 4900
Patent
active
048642924
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND
The present invention relates generally to the field of electronic locking or access-control systems where a user wishing to gain access to a restricted area, or to some service such as the use of a cash-dispensing machine, presents to a receiving apparatus a token which transmits identification data indicative of the user's authority to gain such access. More particularly, the invention relates to a contactless-identification system of the kind where the receiving apparatus includes an alternating magnetic field generator and the token includes a transponder powered by induction from said field.
SUMMARY
As essential component of the transponder in a system of the kind indicated above is a coil or antenna through which the power for operation is induced and through which the identification data is transmitted. In prior art locking system in which this principle of operation has been used at least the antenna (and possibly other components, in particular capacitors) is manufactured and assembled as a discrete component separate from the rest of the transponder circuit, to which it must be electrically connected when assembled to the token. The present invention, on the other hand, proposes in one broad aspect a token for use in an electronic locking or access-control system of the kind indicated above of which the transponder is manufactured as a complete integrated circuit including the antenna. By eliminating the need to make connections between at least a separate antenna and other parts of the transponder circuit the reliability and manufacturing cost of a token in accordance with the invention should be respectively increased and decreased in comparison with those used in prior art systems.
BRIEF DESCRIPTION OF DRAWINGS
This and other features of the present invention will now be more particularly described, by way of example, with reference to the accompanying drawings, in which:
FIG. 1 is a schematic block diagram of a system operating in accordance with the invention as applied to physical access-control;
FIGS. 2-6 are schematic block diagrams of various circuits illustrating the development of a suitable transponder in accordance with the invention;
FIG. 7 illustrates schematically an example of the implementation of transponder as an integrated circuit; and
FIGS. 8A-8D include several schematic block diagrams illustrating the development of a suitable transmitter for use in the system.
DETAILED DESCRIPTION OF DRAWINGS
Referring to FIG. 1, the illustrated access-control system comprises a receiving apparatus 1 to which users present an individual identification token 2 when entry through a normally-locked door 3 is required. When a token is presented to the apparatus its presence is sensed by a detector 4 which instructs the central logic unit 5 to activate a transmitter 6. The latter energises the primary coil 7 of an alternating magnetic field generator comprising a ferromagnetic core 8 which forms a magnetic loop with a small gap 8A. When the token 2 is presented to the apparatus an integrated circuit transponder 9 carried by it is placed within the gap 8A and is subjected to the alternating field concentrated by the core 8. As more particularly described below the transponder is thus caused to transmit identification data which modulates the magnetic field in the core 8 in amplitude or frequency, or adds a magnetic field with a different frequency, and can be detected by a receiver 10 associated with the transmitter 6. The received data is compared by the logic unit 5 with data stored in an associated memory 11 and if found valid an electromagnetic door release 12 is actuated to permit entry.
The transponder circuit 9 may operate on a principle as illustrated in FIG. 2. An antenna coil L receives the magnetic energy from the generator in the apparatus 1 and provides the circuit with power to function. Diodes D1-D4 rectify the induced voltage in L, capacitor CS buffers the supply voltage VDD, while zener diode ZD limits the maximum supply voltage. The frequency of the altern
REFERENCES:
patent: 3440633 (1969-04-01), Vinding
patent: 3696383 (1972-10-01), Oishi et al.
patent: 4371867 (1983-02-01), Gander
patent: 4388524 (1983-06-01), Walton
patent: 4549176 (1985-10-01), Kreft
patent: 4580041 (1986-04-01), Walton
Nederlandse Organisatie voor Toegepast-Natuurwetenschappelijk On
Pudpud E. O.
Yusko Donald J.
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