JP2682233B2 - Moving object identification device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a mobile body identification device for identifying a mobile body by communication between an interrogator and a responder attached to the mobile body, for example.

[Conventional technology]

Conventionally, in a transponder used in a mobile body identification device, as disclosed in, for example, Japanese Patent Laid-Open No. 59-37477, a receiving antenna for receiving an inquiry radio wave and a transmitting antenna for transmitting a response radio wave are provided. There are transponders equipped with each independently.

However, since the transponder disclosed in the above publication requires two types of antennas, one for receiving and the other for transmitting,
There is a problem that the transponder becomes large in size.

Therefore, as a transponder for a mobile body identification device that solves this problem, there is a transponder in which two types of antennas, one for reception and the other for transmission, are shared by a single antenna by increasing the isolation of reception and transmission. (For example, Sharp Technical Report, No. 41, 1989).

[Problems to be solved by the invention]

However, in the above-mentioned transponder, since the isolation of reception and transmission is enhanced by using the hybrid ring, although the number of antennas can be one, the circuit scale becomes large, and eventually the device becomes large. There is a problem.

Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide a moving object identification device that can be downsized and can prevent malfunctions as much as possible.

[Means for solving the problem]

Therefore, the present invention is an interrogator that transmits an interrogation radio wave, and a mobile body identification device that is mounted on a mobile body and has a transponder that transmits a response radio wave including identification information according to the interrogation radio wave, wherein the transponder is: One antenna that receives the inquiry radio wave and transmits the response radio wave, and a first predetermined amount of electric power that is connected to this antenna and is a part of the received electric power of the inquiry radio wave received by the antenna When it is determined that the detection means for detecting the first signal and the first predetermined amount of power included in the first signal detected by the detection means are equal to or higher than a predetermined level, a transmission command is issued. Operation determining means for outputting a signal, generating means for generating the identification information stored in advance in response to the input of the transmission command signal output from the operation determining means, Is connected to the antenna in parallel with a stage, and distributes the received power of the interrogation radio wave to the first predetermined amount of power and the second predetermined amount of power according to the impedance amount of the detection means and the impedance amount of itself. , The impedance amount of the device itself is changed according to the identification information from the information generating means, and the second signal having the second predetermined amount of power is modulated and transmitted as the response radio wave. A mobile unit identification device is provided which is equipped with a modulator.

(Effects)

With the above configuration, in the present invention, the received power of the interrogation radio wave received by the antenna is distributed to the first and second predetermined amounts of power by the impedance amounts of the detection means and the modulation means. Then, it is determined whether or not the response radio wave is transmitted by the first signal having the first predetermined amount of electric power, and when the response radio wave is transmitted, the second predetermined amount of electric power is set in accordance with the identification information. A response radio wave is transmitted from the antenna by modulating the second signal that it has.

Therefore, the antenna for receiving the inquiry radio wave and the antenna for transmitting the responder radio wave modulated according to the identification information can be shared without using a hybrid ring or the like, and the device can be downsized. It has an excellent effect that it can be done.

Further, since the predetermined amount of power of each of the distributed inquiry radio waves is used for the transmission propriety determination and the response radio wave generation, the reception state of the received radio waves is constantly monitored by the detection means and the operation determination means while generating the response radio waves. You can Therefore, for example, even when a noise radio wave having a strong local level is temporarily received, the reception level is monitored one by one by the detection means and the operation determination means, and the radio wave received earlier is a temporary noise radio wave on the way. Therefore, there is an excellent effect that the transmission of the response radio wave can be immediately stopped and the malfunction can be reduced as much as possible.

〔Example〕

 Hereinafter, the present invention will be described based on an embodiment shown in the drawings.

FIG. 1 is a block diagram showing a schematic configuration of a moving body identifying apparatus having a responder as an embodiment of the present invention.

In FIG. 1, the mobile body identification device is composed of a fixed station (interrogator) A that is fixed and a mobile station (responder) B that is installed in a mobile body such as a vehicle or an article.

The transponder B receives the radio wave transmitted from the interrogator A (hereinafter referred to as the interrogation signal S1), and transmits the received radio wave to the unique identification data (for example, the mobile body in which the transponder B is installed) It is configured to be modulated by an ID code) and to transmit the modulated wave (hereinafter referred to as response signal S2) to the interrogator A.

On the other hand, the interrogator A transmits the interrogation signal S1 in a predetermined direction, causes the transponder B installed in the moving body passing through the specific place to output the response signal S2 modulated as described above, and outputs the response signal S2. The mobile station on which the transponder B is mounted is identified by receiving and demodulating the identification data.

Hereinafter, the configurations of the interrogator A and the responder B will be described in detail.

In FIG. 1, an interrogator A transmits an interrogation signal oscillator A2 that oscillates an interrogation signal S1, an amplifier A3 that amplifies the oscillated interrogation signal S1, and an amplified interrogation signal S1 and receives a response signal S2. A transmission / reception antenna A1, a circulator A4 for switching the transmission / reception state, a demodulator A5 for demodulating the response signal S2 output from the responder B, the demodulated response signal
Central processing unit (hereinafter CP
A) and an output device A7 that outputs the analysis result (identification data) of the CPU A6 to an external device.

On the other hand, the responder B transmits and receives the response signal S2 and receives the interrogation signal S2.
A modulation detection unit C that modulates a part of the received inquiry signal S1 and detects a part of it, a code generation unit D (corresponding to generation means) that has a memory for storing data, and a determination unit that determines an operation based on the detection result. G (corresponding to operation determination means), and a power supply H for supplying power to the code generation section D and the determination section G. Further, the modulation detection section C is composed of a modulator E (corresponding to the modulation means) and a detector F (corresponding to the detection means).

Next, a specific configuration of the above-described device of the present invention will be described.

FIG. 2 shows a transmitting / receiving antenna B1 and a modulation detection unit C.
FIG. 3 is a circuit diagram showing a specific configuration of FIG.

In FIG. 2, the transmitting / receiving antenna B1 is a microstrip antenna, and the electric power received by this antenna passes through the microstrip line 82 and the detection diode.
Guided to 90. A stub 83 is meshed in the middle of the microstrip line 82, and the tip of the stub 83 is grounded.

The anode side of the detection diode 90 is connected to the microstrip line 82, and the cathode side is connected to the microstrip line 84. Micro strip line
The line length of 84 is set to 1/4 of the wavelength on the substrate.
Further, a resistance 85 and a capacitor 86 are connected in parallel to the microstrip line 84, and the opposite sides thereof are installed. And the detector F is comprised by each element mentioned above.

Transmitting / receiving antenna B1 and microstrip line 82
A capacitor 87, a diode 88, a resistor 8
A modulator E composed of 9 and a feedthrough capacitor 91 is connected. Reference numeral 92 is a modulation terminal, and 93 is a detection terminal, both terminals being connected to the code generator D (FIG. 1).

Here, the operation of the above configuration will be described with reference to the Smith chart of FIG.

The potential of the modulation terminal 92 (the code generator D shown in FIG.
If the identification data level output by is 0V,
The resistance of the diode 88 becomes infinite, which is equivalent to that the modulator E is not connected to the transmitting / receiving antenna B1. As a result, the impedance of the modulator E and the detector F seen from the transmission / reception antenna B1 is set to point I as shown in FIG. 3 (for example, VSWR = 5 to 6). The VSWR is the voltage standing wave ratio.

Therefore, 67-72% of the radio waves (interrogation signal) received by the transmitting / receiving antenna B1 is re-radiated by the transmitting / receiving antenna B1, and 28-33% of the electric waves are guided to the detector F.

When the potential of the modulation terminal 92 is set to a predetermined potential,
The diode 88 becomes conductive, and a load (R + 1 / jωc) composed of the capacitor 87 and the diode 88 is added in parallel, and the transmitting / receiving antenna B1 is turned on as shown in FIG.
It is set to be II (for example, VSWR = 1).

Therefore, most of the radio waves received by the transmission / reception antenna B1 are output to the detection diode 90 and output to the detection terminal 93 via the microstrip line 84.

Next, specific configurations of the determination unit G, the code generation unit D, and the power supply H will be described.

FIG. 4 is a circuit diagram showing a specific configuration of the determination unit G, the code generation unit D, and the power supply H.

In Fig. 4, the detection terminal of the transmitting / receiving antenna B1
Reference numeral 93 is connected to the connection between a resistor 101 connected to the non-inverting input terminal of an operational amplifier (for example, TLC271 manufactured by TI) and a capacitor 112 connected to the base terminal of the transistor 110.

The set voltage via the resistor 102 is applied to the inverting input terminal of the operational amplifier 100 from the terminal 103, and the output of the operational amplifier 100 passes through the diode 104 and the inverter IC 107 (for example, manufactured by TI
74HC00) is input. The cathode side of the diode 104 is grounded by the resistor 105 and the capacitor 106.

The output of the inverter IC 107 is input to an input / output port (hereinafter, I / O port) of a central processing unit (hereinafter, CPU) 130 via the inverter IC 108. The power supplies of the operational amplifier 100 and the inverter ICs 107 and 108 described above are supplied via a terminal V _B directly connected to the battery 123. Further, the set voltage applied to the terminal 103 is
Configured with terminal V _B as the source.

A resistor 111 is provided between the base terminal and the collector terminal of the transistor 110, and the emitter terminal of the transistor 110 is grounded.

The collector terminal of the transistor 110 is connected to the inverter IC 114 via the capacitor 113, and the resistor 115 is provided between the input and the output of the inverter IC 114. The power source of the transistor 110 and the inverter IC 114 described above is the transistor 12 connected to the battery 123.
Supplied from terminal V _CC via 0.

A resistor 122 is provided between the emitter terminal and the base terminal of the transistor 120, and the base terminal of the transistor 120 is connected to the I / O port of the CPU 130 via the resistor 121. CPU130 is connected with RAM140, CPU130 and
The RAM 140 is directly connected to the power supply 123 via the terminal V _B.

 Next, the operation in FIG. 4 will be described.

In Fig. 4, the interrogator A (Fig. 1) sends the interrogation signal SI.
Is transmitted and the transmission / reception antenna B1 receives the inquiry signal SI, power proportional to the reception power is generated at the detection terminal 93 of the transmission / reception antenna B1.

Then, in the operational amplifier 100, the voltage level (detection level) generated at the detection terminal 93 is compared with the set potential applied from the terminal 103. If the detected level is higher than the set potential, the operational amplifier 100 Output a high level signal.

Therefore, at the input terminal of the inverter IC107, the diode of the high level signal voltage output from the operational amplifier
The voltage obtained by subtracting the voltage drop of 104 is applied.

Then, this inverter IC107 judges that the applied voltage is high level and outputs a low level signal to the inverter IC108.
The inverter IC 108 inputs this low level signal and outputs a high level signal.

When the CPU 130 detects the high-level signal output from the inverter IC 108, it determines that it has received the interrogation signal S1 transmitted by the interrogator A (FIG. 1), and the operating signal is set to the resistor 121 so that the transistor 120 becomes conductive. Through the transistor 1
Output to 20. As a result, transistor 120 becomes conductive, and power is supplied to transistor 110 and inverter IC 114 via terminal V _CC .

Then, the circuit including the transistor 110 and the inverter IC 114 operates as an amplifier circuit, amplifies a part of the interrogation signal S1 from the interrogator, and inputs the amplified signal to the CPU 130.

The CPU 130 intermittently processes the input signal.
For example, when writing movement data to the responder B, RA
When the movement data is written in the M140, and conversely, when the movement data is read out, the movement data written in the RAM140 is read out and the modulator E of the transmission / reception antenna B1 is operated, and the interrogator A (Fig. 1). Send move data to.

As described above, in the above-described embodiment, part of the power of the received signal S1 received is used for detection, and the remaining power is used for modulation, so the antenna can be used for both transmission and reception. Therefore, the device can be downsized.

Also, with a feedthrough capacitor that blocks high frequency signals,
The circuit section and the high frequency section can be easily separated, and the modulator section can be designed compactly.

Furthermore, by providing a wave detector, the identification data can be updated (RAM rewriting) according to the voltage level of the inquiry signal S1.

In the above-described transponder, the detection level is lower than the predetermined level even if the transmitting / receiving antenna B1 receives a noise radio wave or the like when the interrogator A (FIG. 1) does not transmit the interrogation signal S1. The operation of the determination unit G described above is not performed, and thus it is possible to prevent malfunction due to noise radio waves or the like.

Further, for example, even when a noise radio wave having a locally strong level is temporarily received, the reception level is monitored by the detector F and the determination unit G one by one, and the radio wave received earlier is a temporary noise radio wave on the way. Since it can be determined that there is a response, the transmission of the response radio wave can be immediately stopped, and the malfunction can be reduced as much as possible.

 Next, another embodiment of the modulation detector C will be described.

FIG. 5 is a circuit diagram showing the configuration of the modulation detection section in another embodiment. It should be noted that, in the drawing numbers in FIG. 5, the parts having the same numbers as the drawing numbers in FIG. 2 indicate the parts equivalent to the drawing numbers in FIG.

All the components of the transponder in this embodiment are arranged on the same printed board, but as shown in FIG.
Transmitter / receiver antenna B1, microstrip line 2,
The stub 83 and the microstrip line 4 are arranged on the front surface of the printed board 95, and other components are arranged on the rear surface of the printed board 95, and the front surface and the rear surface are connected by through holes. Since the operation is the same as that of the above-mentioned embodiment, the explanation is omitted.

By configuring as shown in FIG. 5, it is possible to realize further miniaturization.

Next, still another embodiment of the modulation detector C will be described.

FIG. 6 is a circuit diagram showing the configuration of the modulation detection section in still another embodiment. It is to be noted that, in the drawing numbers in FIG. 6, the parts having the same numbers as the drawing numbers in FIG. 2 indicate the parts equivalent to the drawing numbers in FIG.

In FIG. 6, the microstrip antenna 94 is
This is an antenna for degenerate separation for circular polarization, and the modulator E is connected to the microstrip line 82 so as to form an angle of 90 °.

Then, the right-handed circularly polarized wave transmitted from the interrogator A (FIG. 1) is guided to the detector F and detected. On the other hand, Interrogator A
The left-handed circularly polarized wave transmitted from (FIG. 1) is guided to the modulator E and modulated.

With this setting, the interrogator requires two types of antennas for transmitting right-handed circularly polarized waves and left-handed circularly polarized waves, but requires right-handed circularly polarized waves that have the power required for detection and modulation. Since it is possible to individually set the left-handed circular polarization and
The electric power of the received radio wave can be used more efficiently.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a circuit diagram showing a modulation detector in the above embodiment, and FIG. 3 is a diagram for explaining the operation of the modulation detector. Smith chart, FIG. 4 is a circuit diagram showing the entire configuration excluding the modulation detector in the above embodiment, FIG. 5 is a circuit diagram showing the modulation detector in another embodiment, and FIG. It is a circuit diagram which shows the modulation detection part in other Examples. B1 ... Antenna for both transmission and reception (antenna), D ... Code generator (generation means), E ... Modulator (corresponding to modulation means), F ...
Detector (corresponding to detection means), G ... Judgment part (operation judgment means).

Claims (1)

(57) [Claims] 1. A mobile body identification device having an interrogator for transmitting an interrogation radio wave and a transponder mounted on a mobile body and transmitting a response radio wave including identification information according to the interrogation radio wave, wherein the transponder comprises: One antenna that receives the inquiry radio wave and transmits the response radio wave, and a first predetermined amount of electric power that is connected to this antenna and is a part of the received electric power of the inquiry radio wave received by the antenna When it is determined that the detection means for detecting the first signal and the first predetermined amount of power included in the first signal detected by the detection means are equal to or higher than a predetermined level, a transmission command is issued. An operation determining means for outputting a signal; a generating means for generating the identification information stored in advance in response to the input of the transmission command signal output from the operation determining means; Are connected to the antenna, and the received power of the interrogation radio wave is distributed to the first predetermined amount of power and the second predetermined amount of power according to the impedance amount of the detection unit and the impedance amount of the detection unit itself, and A modulation unit that modulates the second signal having the second predetermined amount of electric power and transmits the response signal as the response radio wave by changing the amount of impedance of the second generation unit according to the identification information from the information generation unit. A moving body identification device comprising: