Active transponder with means allowing the maximum communication distance to be varied

• US 7,015,794 B2
• Filed: 04/02/2001
• Issued: 03/21/2006
• Est. Priority Date: 04/06/2000
• Status: Expired due to Term

• Current Assignee: EM Microelectronic - Marin SA (The Swatch Group AG)
• Original Assignee: EM Microelectronic - Marin SA (The Swatch Group AG)
• Inventors: Degrauwe, Marc, Roz, Thierry, Rudin, Jürg
• Primary Examiner(s): Horabik, Michael
• Assistant Examiner(s): JENKINS, KIMBERLY YVETTE
• Application Number:
  US09/822,222
• Publication Number:
  US 20010028302A1
• Time in Patent Office: 1,814 Days
• Field of Search: 340 101- 105, 340/5.61, 340/5.1, 340/10.34
• US Class Current: 340/10.4
• CPC Class Codes: G06K 19/0723 the record carrier comprising an arrangement for non-contact communication, e.g. wireless communication circuits on transponder cards, non-contact smart cards or RFIDs
• CPC Class Codes: G06K 19/07777 the antenna being of the inductive type

Abstract

The active transponder is intended for several applications or to operate in various modes requiring different levels of security. Security is controlled by varying the maximum communication distance to a reader. The active transponder includes a battery (2) powering the various electronic circuits amplifying component (8), a module (4) forming a demodulator for the incoming signals, and a component for validating the data comprised in the signals, and a data processing unit (10). The unit includes circuit (12) for controlling the maximum communication distance between the transponder and a reader transmitting signals at a determined power. Circuit (12) sends a security signal (S1, S2) respectively to the data validating component and/or to the signal amplifying component. This signal is used either to control the value of the reference value of the validating component, or to vary the gain of the amplifying component to vary the maximum communication distance.

Claims

1. An active transponder including:

an electronic unit arranged so as to control several applications or operating modes;

an antenna for receiving incoming signals carrying data; and

an electric power supply connected to said electronic unit, wherein said electronic unit includes;

a data processing unit;

means for amplifying incoming signals received by said antenna, and

means for validating the incoming signals as a function of mean induced voltages in said antenna, wherein the validating means supplies to said data processing unit a validating signal for data contained in a first incoming signal when a mean voltage on an input side of the data processing unit is greater than or equal to a determined reference voltage, wherein the data processing unit includes means for varying the maximum communication distance to a reader or transceiver as a function of the application selected from said several applications or the operating mode selected from said operating modes, wherein the means for varying the maximum communication distance is arranged to vary one or both of amplification gain of said amplification means and said reference voltage of said validating means.

2. A transponder according to claim 1, wherein said validating means includes a comparator having a first input and a second input, wherein the first input is connected to means supplying the mean induced voltage of the incoming signal, before or after said means for amplifying incoming signals, and the second input is connected to means supplying said reference voltage.

3. A transponder according to claim 2, wherein said reference voltage is variable and defined by a security signal so that the value of said reference voltage is relatively high when the selected application or operating mode is provided with a high level of security.

4. A transponder according to claim 2, wherein said reference voltage is fixed, and said amplification gain is variable and defined by a security signal so that the value of said amplification gain is relatively low when the selected application or operating mode is provided with a high level of security.

5. A transponder according to claim 3, wherein said means for varying the maximum communication distance includes a memory in which a security code is stored for each application and for each operating mode able to be selected in the transponder, wherein these security codes are used to generate said security signal.

6. A transponder according to claim 4, wherein said means for varying the maximum communication distance includes a memory in which a security code is stored for each application and for each operating mode able to be selected in the transponder, wherein these security codes are used to generate said security signal.

7. A transponder according to claim 1, wherein the electric power supply is a battery.