Transponder used in a remote identification system

• US 5,642,103 A
• Filed: 06/14/1994
• Issued: 06/24/1997
• Est. Priority Date: 10/01/1990
• Status: Expired due to Term

• Current Assignee: Sharp Electronics Corporation (Hon Hai Precision Industry Co., Ltd.), Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Ohta, Tomozo, Tokuda, Masamori, Nakano, Hiroshi
• Primary Examiner(s): Swarthout, Brent A.
• Assistant Examiner(s): HILL, ANDREW M
• Application Number:
  US08/267,291
• Time in Patent Office: 1,106 Days
• Field of Search: 340/825.54, 359/169, 343/700 MS, 235/379, 235/380, 235/383, 235/491, 342/44, 342/50, 342/51, 342/361
• US Class Current: 340/10.51
• CPC Class Codes: G01S 13/756 using a signal generator for modifying the reflectivity of the reflector G01S13/758 takes precedence
• CPC Class Codes: G01S 7/024 using polarisation effects in waveguides H01P1/165; for aerials H01Q, e.g. H01Q15/22, H01Q15/24, H01Q19/195
• 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 19/07703 the interface being visual
• CPC Class Codes: G07B 15/063 using wireless information transmission between the vehicle and a fixed station identification of vehicles G08G
• CPC Class Codes: G07C 9/28 the pass enabling tracking or indicating presence

Abstract

A transponder used in a remote identification system requiring an interrogator and a transponder. The transponder which is thin and compact includes a transmit/receive antenna which is thin for receiving an interrogating signal and a rewrite signal emitted from the interrogator, and for emitting a response signal towards the interrogator. There is a modulator/demodulator for modulating a signal according to a code inherent in the transponder to emit the same from the antenna as the response signal without newly applying energy to the interrogating signal, and for demodulating the rewrite signal. A controller for applying a modulating signal generated according to the inherent code to the modulator/demodulator and for storing a signal demodulated by the modulator/demodulator. A liquid crystal display is used for displaying data including bar codes which can be read by a bar code reader. The bar code can be rewritten.

Claims

1. A transponder for use in a remote identification system requiring an interrogator, the transponder, comprising:

a transmit/receive antenna for receiving an interrogating signal and a rewrite signal emitted from said interrogator, and for emitting a response signal towards said interrogator,

a modulator/demodulator for receiving said interrogating signal and for emitting said response signal from and to the transmit/receive antenna, the response signal being formed of a pattern of one of total reflection of the interrogating signal and absorption, the pattern being determined according to a modulation signal, the modulation signal being a function of a code specifically related to said transponder, thereby forming the response signal without newly applying energy to said interrogating signal, and for demodulating said rewrite signal,

wherein said modulator/demodulator includes;

a polarized wave selection circuit, operatively connected to a reflection type modulator, and a demodulator,

said reflection type modulator including a first impedance converter operatively connected to a first bias circuit, the converter and bias circuit formed as micro strip lines and a first diode operatively connected to the first impedance converter;

said demodulator including a second impedance converter operatively connected to a second bias circuit, the converter and bias circuit formed as micro strip lines and a second diode operatively connected to the second impedance converter;

said polarized wave selection circuit directing said interrogation signal received by said transmit/receive antenna to said reflection type modulator, and directing said rewrite signal to said demodulator,

a dielectric substrate having a first surface and a second surface oppositively opposed to each other,

said polarized wave selection circuit, said first impedance converter, said first bias circuit, said second impedance converter, said second bias circuit and said first and second diodes located on said first surface and operatively connected to each other,

a ground conductor formed on said second surface,

a controller for applying a modulation signal generated according to said code to said modulator/demodulator, and for storing a signal demodulated by said modulator/demodulator,

a liquid crystal display of dot matrix for displaying various types of data operatively connected to said controller, said reflection type modulator modulating said interrogating signal according to said modulation signal from said controller to emit said modulation signal as said response signal to said transmit/receive antenna via said polarized wave selection circuit,

said demodulator demodulating said rewrite signal and providing the rewrite signal to said controller, and

a battery operatively connected to the controller for supplying power, the transmit/receive antenna is in a microwave range, and the two impedance converters are each optimized for their respective modulator and demodulator circuits, whereby the impedance converter of the reflection type modulator is adjusted so that the applied interrogating signal is perfectly reflected or absorbed according to the modulation signal attaining high or low potential and the impedance converter of the demodulator is adjusted so that the rewrite signal is absorbed by the diode of the demodulator so that demodulation is carried out by the diode and a demodulated signal is derived by the bias circuit of the demodulator and provided therefrom to the controller.

2. The transponder according to claim 1 wherein

said transmit/receive antenna comprises a print antenna formed on said first surface of said dielectric substrate.

3. The transponder according to claim 1, further including means for presenting bar codes in dot matrix on the liquid crystal display, so that the bar code can be read by a bar code reader.

4. The transponder according to claim 3, wherein the bar codes can be rewritten.

5. A transponder for use in an identification system requiring an interrogator, said transponder, comprising:

a dielectric substrate having a first surface and a second surface oppositively opposed to each other, the dielectric substrate having mounted on the first surface;

a transmit/receive antenna,

a modulator/demodulator operatively connected to the transmit/receive antenna, the modulator/demodulator including a micro-strip line impedance converter operatively connected to a micro-strip line bias circuit and a diode operatively connected to the impedance converter,

a controller operatively connected to the modulator/demodulator,

a flat battery operatively connected to the controller,

a liquid crystal dot matrix display operatively connected to the controller, and

a ground conductor mounted on said second surface,

wherein the impedance converter is adjusted so that an applied interrogating signal is totally reflected or absorbed according to a modulation signal attaining high or low potential to emit a response signal, the response signal being formed of a pattern of one of total reflection of the interrogating signal add absorption, the pattern being determined according to a modulation signal, the modulation signal being a function of a code specifically related to the transponder thereby forming a response signal without newly applying energy to the interrogating signal, and that the diode is at a non-biased state to carry out demodulation of a rewrite signal to provide demodulated data to the controller.