Electromagnetic field generation device for a transponder

• US 20020017991A1
• Filed: 05/17/2001
• Published: 02/14/2002
• Est. Priority Date: 05/17/2000
• Status: Active Grant

• Current Assignee: STMicroelectronics SA (STMicroelectronics NV)
• Original Assignee: STMicroelectronics SA (STMicroelectronics NV)
• Inventors: Wuidart, Luc, Bardouillet, Michel
• Granted Patent: US 7,046,146 B2
• Time in Patent Office: Days
• US Class Current: 340/572.1
• CPC Class Codes: G06K 19/07767 the first and second communication means being two different antennas types, e.g. dipole and coil type, or two antennas of the same kind but operating at different frequencies
• CPC Class Codes: G06K 7/0008 General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer
• CPC Class Codes: G06K 7/10178 including auxiliary means for focusing, repeating or boosting the electromagnetic interrogation field comparable booster antennas integrated on the record carrier itself G06K19/07794
• CPC Class Codes: G06K 7/10336 the antenna being of the near field type, inductive coil

Abstract

A device for generating an electromagnetic field by a first oscillating circuit excited by a high-frequency signal, including, at a distance from the first oscillating circuit, a second passive, unloaded and coreless oscillating circuit, forming an element for concentrating the magnetic flux intended to be intercepted by a transponder by a third oscillating circuit.

Claims

1. A device for generating an electromagnetic field of a first oscillating circuit excited by a high-frequency signal, including, at a distance from the first oscillating circuit, a second passive, unloaded and coreless oscillating circuit, forming an element for concentrating the magnetic flux intended to be received by a transponder by a third oscillating circuit.

2. The device of claim 1, wherein the second oscillating circuit and the first oscillating circuit have approximately identical natural resonance frequencies chosen, preferably, to approximately correspond to the frequency of the excitation signal of the first oscillating circuit.

3. The device of claim 1, wherein the second oscillating circuit includes at least one planar inductance, a general surface area of which is inscribed in a surface area greater than that in which is inscribed an inductance included in the third oscillating circuit of a transponder intended for receiving the magnetic flux.

4. The device of claim 1, wherein the second oscillating circuit includes at least one planar inductance, a general surface area of which is inscribed in a surface area greater than or equal to that in which is inscribed an inductance included in the first oscillating circuit.

5. The device of claim 4, wherein an orientation of the planes in which are inscribed planar inductances of the first and second oscillating circuits is chosen according to desired privileged operating areas.

6. The device of claim 1, wherein the concentrator includes at least two voltage or current sampling terminals.

7. A magnetic flux concentrator adapted to cooperating with an element for generating an electromagnetic field in the device of claim 1, this concentrator being formed of an oscillating circuit provided with a single inductance in parallel with a capacitor.

8. A magnetic flux concentrator adapted to cooperating with an element for generating an electromagnetic field in the device of claim 1, including n oscillating circuits with coplanar inductances.

9. A magnetic flux concentrator adapted to cooperating with an element for generating an electromagnetic field in the device of claim 1, including n coplanar inductances, in parallel with a single capacitor.

10. A system of information exchange between an electromagnetic transponder and a read and/or write terminal, including the device for generating an electromagnetic field of claim 1.

11. The system of claim 10, wherein the electromagnetic field generation device includes the concentrator of claim 7.

12. The system of claim 11, wherein the electromagnetic field generation device includes the concentrator of claim 8.

13. The system of claim 10, wherein the electromagnetic field generation device includes the concentrator of claim 9.