JPH02218986A - Transponder for discrimination of moving body - Google Patents

Abstract

PURPOSE:To make an apparatus small in size and to reduce power consumption by modulating a signal of a microwave band from an interrogating device by one diode and by breaking a power source of an unnecessary circuit outside an emission area of the signal of the microwave band. CONSTITUTION:A control element 9 of a transponder is ordinarily out of operation, and when the transponder approaches a service area of an interrogating device, a microwave transmitted from the inerrogating device and received by an antenna 1 is detected by a diode 4. When a detection output thereof exceeds a prescribed value, the control element 9 is started and put in a state of operation. The antenna 1 and a modulator 10 are in matched states at this time, the microwave is taken in efficiently from the antenna 1, and the detection sensitivity of the diode 4 can be made high. In the service area, the transponder impresses a non-bias or reverse-bias voltage on the diode 4 through a diode 7 in accordance with internal data of the control element 9. When the reverse- bias voltage is impressed, the modulator 10 is put in a state of mismatch in impedance with the antenna 1 and a microwave signal is reflected totally by the antenna 1.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is particularly aimed at reducing the power consumption of a transponder. This invention relates to a transponder for mobile object identification using microwaves.

BACKGROUND OF THE INVENTION In recent years, mobile object identification devices using microwaves have been actively developed.

A mobile object identification device is a transponder installed on a mobile object that emits electromagnetic waves from a fixed interrogation device toward the mobile object.
The transmitted wave from the interrogation device is subjected to some modulation (amplitude modulation, phase modulation, etc.) based on the internal data of the transponder, the reflected wave is sent back to the interrogation device, and the modulated reflected wave is sent back to the interrogation device. By detecting waves, the information transmitted from the mobile object can be read.

FIG. 2 shows the basic configuration of a conventional mobile object identification device using microwaves. In FIG. 2, 2.1 is an interrogator, and 22 is a responder.

The interrogation device 21 includes a signal generator 23 that generates a microwave band signal, a demodulator 24 that receives and demodulates the microwave band signal reflected from the transponder 22, and the signal generator 2.
3 to the transponder 22;
It is comprised of a circulator 25 that separates the microwave band reception signal reflected from the transponder 22, and an antenna 26 that transmits and receives the microwave band signal.

On the other hand, the responder 22 includes a control section 27 that generates sending data.
, a modulator 28 that modulates a microwave band transmission signal transmitted from the interrogation device 21 using a signal from the control section 27;
and an antenna 29 that transmits and receives microwave band signals.
It is composed of a lot of things.

In the mobile object identification device described above, a microwave band signal sent out from the signal generator 23 of the interrogation device 21 is transmitted from the transmission and reception antenna 26 to the transponder 22. The transmitted microwave band signal is transmitted to the antenna 29 of the transponder 22.
The signal is received by the controller 27, modulated by the modulator 28 based on internal data of the control unit 27, and transmitted from the antenna 29 toward the interrogation device.

Then, the interrogator 21 receives the signal transmitted from the transponder 22 with the antenna 26, separates the transmitted signal from the signal generator 23 with the circulator 25, and demodulates the received signal with the demodulator 24. Can read 22 pieces of information.

Problems to be Solved by the Invention Now, in a mobile object identification device system, the interrogation device 21 is normally installed in a fixed manner, and the transponder 22 is installed in the mobile object. Since the transponder 22 is installed in a moving body, it usually uses a battery as a power source, so it is required to be small and have low power consumption. A method was used in which the microwave band signal transmitted from the interrogation device 21 is reflected and absorbed to modulate its amplitude using a varactor diode whose impedance can be greatly changed by electric power.

On the other hand, in order to reduce the power consumption of the control unit 27.

If the microwave band signal from the interrogator 21 cannot be received by the transponder 22, it may be possible to turn off the power to unnecessary circuits, but this would require an additional microwave detection circuit. Therefore, it has been difficult to realize a transponder with low power consumption.

The present invention solves the above problems and provides a small transponder with low power consumption in a mobile object identification device using microwaves.

Means for Solving the Problems In order to achieve the above object, the present invention applies modulation to a microwave band signal emitted from an interrogation device by changing the impedance of a diode, and also modulates a microwave band signal emitted from an interrogation device by changing the impedance of a diode. The system is configured to detect the radiation area of microwave band signals.

Function: With the above configuration, the present invention modulates the microwave band signal from the interrogation device with one diode, and
The aim is to reduce the size and power consumption of the transponder by detecting the radiation area of the microwave band signal and turning off the power to unnecessary circuits of the transponder outside the area. be.

EXAMPLE An example of the present invention will be described below with reference to FIG. FIG. 1 shows an embodiment of a mobile body identification transponder using microwaves according to the present invention.

The transponder includes an antenna 1 that transmits and receives a microwave signal transmitted from an interrogation device (not shown), and amplitude modulates the microwave signal transmitted from the interrogation device according to internal data of a control unit 9. A modulator 10, a resistor 11°12 for applying a modulation signal to the modulator 10, a diode 7, and a control section 9.
It also includes an amplifier 8 that amplifies the detection output obtained by detecting the microwave signal transmitted from the interrogation device by the diode 4 of the modulator 10. Further, when the modulator 10 does not apply a reverse bias voltage to the diode 4, the antenna 1
It has a matching circuit 2 that matches the input impedance of the modulator viewed from the side with the impedance of the antenna 1, and a low-pass filter (LPF) 3 whose impedance is open in the microwave band used and whose diode 4 is grounded in a DC manner. Note that this diode 4 matches or mismatches the input impedance of the modulator 10 with the impedance of the antenna 1 by applying a reverse bias voltage, and detects the microwave signal from the interrogation device in the matched state. Also, one end is open, and one end is connected to the transmission line 5 of approximately 174 wavelengths in the microwave band used, one end is connected to the cathode of the diode 4, and the other end is connected to the amplifier 8,
LPG that is connected to diode 7 and has an open impedance in the microwave band used! Consists of 117.

In the above configuration, the control unit 9 of the responder is normally in a dormant state in order to reduce power consumption.

When the transponder approaches the interrogator's service area,
A diode 4 detects microwaves transmitted from an interrogation device and received by an antenna 1. When the detection output of the diode 4 exceeds a certain value, the control section 9 is activated and becomes operational.

At this time, the antenna 1 and the modulator 10 are in a matching state, and the antenna 1 efficiently absorbs the p microwave.

The detection sensitivity of the diode 4 can be increased.

Furthermore, when the diode 7 is in the OFF state, it has a high impedance when viewed from the diode 4 side, and separates the control section 9 and the amplifier 8 that amplifies the detection output of the diode 4.

Then, when the transponder again moves out of the service area of the interrogation device, the control section 9 returns to the hibernation state.

Within the service area of the interrogator, the transponder applies a non-biased or reverse-biased voltage to the diode 4 of the modulator 10 through the diode 7, depending on the internal data of the control unit 9. In the modulator 10, the diode 4 matches the impedance of the antenna 1 when no bias is applied, and absorbs the microwave signal transmitted from the quality control device. Also, diode 4
When a reverse bias voltage is applied to the antenna 1 , the modulator 10 has an impedance mismatch with the antenna 1 , and the microwave signal transmitted from the interrogation device is totally reflected by the antenna 1 . In this way, ASK modulation can be equivalently applied by changing the reflectance of the antenna 1. Further, at this time, in order to distinguish between the reflected wave from the transponder and the reflected wave from a non-responsive object, subcarrier ASK modulation is used in which a subcarrier is placed on the data signal.

The interrogator receives the subcarrier ASK modulated reflected wave from the responder, detects it, and reproduces the data.
The internal data of the transponder can be read.

In this way, by detecting the service area of the interrogation device and performing ASK modulation with one diode,
A small and low power consumption transponder can be realized.

Effects of the Invention As described above, the present invention provides an extremely effective means for realizing a small and low power consumption transponder in a mobile object identification transponder using microwaves. .

[Brief explanation of the drawing]

FIG. 1 is a block wiring diagram of a transponder for mobile object identification in one embodiment of the present invention, and FIG. 2 is a block wiring diagram showing the basic configuration of a mobile object identification device. DESCRIPTION OF SYMBOLS 1... Antenna, 2... Matching circuit, 3, 6... Low pass filter, 4... Diode, 5... Transmission line, 7... Diode, 8... Amplifier, 9...・・・
Control unit, 10...Modulator, 11.12...Resistor.

Claims (2)

[Claims] (1) The microwave band signal emitted from the interrogation device,
By changing the impedance of the diode, it is reflected, absorbed, modulated, and re-radiated to the interrogation device, and by detecting the microwave band signal from the interrogation device with the diode, the microwave of the interrogation device is A transponder for mobile object identification that detects the radiation area of waveband signals. (2) One end of the diode has an open impedance in the microwave band, and one end is connected to an impedance matching circuit composed of a grounded first low-pass filter and a microstrip line; One end of the diode is connected to the microwave band antenna, and the other end of the diode is connected to a second low-pass filter whose impedance is open in the microwave band. The other end of the pass filter 2 receives the microwave signal from the interrogation device via an amplifier and two diodes arranged in parallel, each anode connected to the cathode of one of the diodes, or a capacitor or a resistor. 2. The transponder for mobile object identification according to claim 1, wherein the transponder is connected to a control section that modulates the transponder.