JPH04190185A - Transponder for discriminating apparatus of moving body - Google Patents

Abstract

PURPOSE:To enable miniaturization by a construction wherein an antenna for receiving an interrogation wave and an antenna for transmitting a reflection wave modulated in accordance with discrimination information are made to be used jointly. CONSTITUTION:An antenna B1 for transmission and reception receives an interrogation signal S1 from an interrogator A. Next, a detector F distributes a power of the signal S1 to first and second powers of prescribed amounts by a reflection coefficient of a detecting element. When a determining element G determines that a voltage level of the first power of the prescribed amount distributed by the detector F is a prescribed level or above, it outputs a transmission instruction signal so as to transmit a response signal S1, and when a code generating element D receives this transmission instruction signal as an input, it generates discrimination information stored beforehand. Moreover, a modulator E changes a bias amount of the detecting element in accordance with the discrimination information outputted from the generating element D and changes a reflection coefficient of the detecting element in accordance with the discrimination information. Thereby the discrimination information is modulated to a reflection wave of the signal S1 having the second power of the prescribed amount and sent as a signal S2 in response from the antenna B1.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a transponder for a mobile object identification device that identifies a mobile object through communication between an interrogator and a transponder attached to the mobile object, for example. be.

[Conventional technology]

Conventionally, a transponder used in a mobile object identification device has a receiving antenna for receiving interrogation radio waves and a transmitting antenna for transmitting response radio waves, as disclosed in Japanese Patent Laid-Open No. 59-37477, for example. There are responders equipped with each independently.

However, the transponder disclosed in the above-mentioned publication requires two types of antennas, one for receiving and one for transmitting, so there is a problem that the transponder becomes large in size.

Therefore, as a transponder for a mobile object identification device that solves this problem, there is a transponder that uses one antenna to share two types of antennas, one for reception and one for transmission, by increasing the isolation of reception and transmission. (For example, Sharp Technical Review, No. 41, 1989).

[Problems to be Solved by the Invention] However, the above-mentioned transponder uses a hybrid ring to improve reception and transmission isolation, so although it is possible to use only one antenna, the circuit scale becomes large. However, there is a problem in that the device ends up becoming larger.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a transponder for a mobile object identification device that can be miniaturized.

[Means to solve the problem]

Therefore, the present invention provides a transponder of a mobile object identification device in which an interrogator receives a response radio wave containing identification information returned from a transponder attached to a mobile object, which includes: receiving an interrogation radio wave from the interrogator; an antenna for transmitting the response radio wave; an allocating means for distributing the power of the interrogation radio wave received by the antenna into first and second predetermined amounts of power according to a reflection coefficient of a detection element; an operation determining means for outputting a transmission command signal to transmit the response radio wave when it is determined that the voltage level of the first predetermined amount of power is equal to or higher than a predetermined level; , a generation means for generating the identification information stored in advance, and a reflection coefficient of the detection element that changes the bias amount of the detection element according to the identification information outputted from the generation means. and bias control means for modulating the identification information into a reflected radio wave of the interrogation radio wave having the second predetermined amount of power by changing it in accordance with the identification information, and replying as the response radio wave. This system employs a transponder for a mobile object identification device.

[Effect]

With the above configuration, the antenna receives the interrogation radio wave from the interrogator and also transmits the response radio wave, and the distribution means converts the power of the interrogation radio wave received by the antenna into first and second predetermined amounts of power using the reflection coefficient of the detection element. It is being distributed.

Then, the operation determining means determines the first
When it is determined that the voltage level of the predetermined amount of power is equal to or higher than the predetermined level, a transmission command signal is outputted to transmit a response radio wave, and when the generation means receives this transmission command signal, it is stored in advance. generated identification information.

Furthermore, the bias control means changes the amount of bias of the detection element according to the identification information output from the generation means,
By changing the reflection coefficient of the detection element according to the identification information, the identification information is modulated into the reflected radio wave of the interrogation radio wave having the second predetermined amount of power, and the reflected radio wave is sent back as a response radio wave.

Therefore, in the present invention, the power of the interrogation radio wave received by the antenna is distributed to the first and second predetermined amounts of power, and the second
It is determined whether or not to transmit a response radio wave based on the first predetermined amount of power, and when the response radio wave is to be transmitted, the inquiry radio wave having the first predetermined amount of power is modulated according to the identification information to respond. Radio waves are returned from the antenna.

〔Effect of the invention〕

As described above, in the present invention, the power of the interrogation radio wave received by the antenna is determined by the reflection coefficient of the detection element.
and a second predetermined amount of power, and it is determined whether or not to transmit a response radio wave using the second predetermined amount of power, and when transmitting a response radio wave, the second predetermined amount of power is allocated to the first location according to the identification information. A question radio wave having a fixed power is modulated and a response radio wave is sent back from the antenna.

Therefore, for example, we have developed a transponder for a mobile object identification device that can share an antenna for receiving interrogation radio waves and an antenna for transmitting reflected radio waves modulated according to identification information without using a hybrid ring. It has the excellent effect of being able to be made smaller.

〔Example] Hereinafter, the present invention will be explained based on embodiments shown in the drawings.

FIG. 1 is a block diagram showing a schematic configuration of a mobile object identification device equipped with a transponder as an embodiment of the present invention.

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

When transponder B receives the radio waves transmitted from interrogator A (hereinafter referred to as interrogation signal Sl), transponder B converts the received radio waves into unique identification data representing the mobile body in which transponder B is installed ( For example, the interrogator A is configured to modulate the modulated wave (hereinafter referred to as a response signal S2) using an ID code) and transmit the modulated wave (hereinafter referred to as a response signal S2) to the interrogator A.

On the other hand, the interrogator A transmits an interrogation signal S1 in a predetermined direction, causes the transponder B installed on a moving body passing through a specific location to output a response signal S2 modulated as described above, and also transmits this response signal S2. receive and demodulate the above identification data,
The mobile body on which the transponder B is mounted is identified.

The configurations of interrogator A and responder B will be described in detail below.

In FIG. 1, an interrogator A includes an interrogation signal oscillator A2 that oscillates an interrogation signal S1, an amplifier A3 that amplifies the oscillated interrogation signal S1, and transmits an amplified interrogation signal SL and receives a response signal S2. Transmitting/receiving antenna AI,
Circulator A4, transponder B that switches the transmission/reception state
a demodulator A5 that demodulates the response signal S2 output from the demodulator A6, a central processing unit (hereinafter referred to as CPU) A6 that analyzes identification data using the demodulated response signal S2, and a CPU.
It is composed of an output device A7 that outputs the analysis result (identification data) of A6 to an external device.

On the other hand, the transponder B has a transmitting/receiving antenna (antenna) B that transmits the response signal S2 and receives the interrogation signal S2.
1. A modulation/detection unit C that modulates a part of the received interrogation signal S1 and detects the part, a code generation unit D (corresponding to a generation means) that has a built-in memory for storing data, and determines the operation based on the detection result. A power supply H that supplies power to the determination section G (corresponding to the operation determination means), the code generation section, and the determination section G.
It is made up of. Further, the modulation detection section C is composed of a modulator E (corresponding to bias control means) and a detector F (corresponding to distribution means).

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

Figure 2 shows the transmitting/receiving antenna B1 and the modulation/detection section C.
FIG. 2 is a circuit diagram showing a specific configuration.

In FIG. 2, a transmitting/receiving antenna B1 is a microstrip antenna, and the power received by this antenna passes through a microstrip line 82 and is guided to a detection diode 90. A stub 83 is provided 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.

The line length of the micro strip and pline 84 is set to 174 wavelengths on the substrate. Also, microstri
A resistor 85 and a capacitor 86 are connected in parallel to the knob line 84, and the opposite sides of each are grounded. The detector F is constituted by each of the elements described above.

Transmitting/receiving antenna B1 and microstrip line 8
At the connection point with 2, a capacitor 87, a diode 88,
A modulator E composed of a resistor 89 and a feedthrough capacitor 91 is connected.

Note that 92 is a modulation terminal, and 93 is a detection terminal, both of which are connected to the code generator D (FIG. 1).

Here, the operation of the above configuration will be explained using the Smith chart shown in FIG.

If the potential of the modulation terminal 92 (the level of the identification data output from the code generator shown in FIG. 1) is OV, then
The resistance of the diode 88 becomes infinite, which is equivalent to the fact that the modulator E is not connected to the transmitting/receiving antenna B1. As a result, the impedance seen from the transmitting/receiving antenna Bl to the modulator E and the detector F is set to point I as shown in FIG. 3 (for example, VSWR=
5-6) be done. Note that VSWR refers to voltage standing wave ratio.

Therefore, 67 to 72% of the radio waves (interrogation signal) received by the transmitter/receiver antenna B1 are transmitted to the transmitter/receiver antenna B1.
1, and 28 to 33% of the radio waves are guided to the detector F.

Further, when the potential of the modulation terminal 92 is set to a predetermined potential,
The diode 88 becomes conductive, a load (R+1/jωC) consisting of the capacitor 87 and the diode 88 is applied in parallel, and the transmitting/receiving antenna B1 is set to the point ■ as shown in FIG. 3 (for example, , vswR=1
) to be done.

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

Next, the specific configurations of the determination section G, code generation section D, and electric power BH will be explained.

FIG. 4 shows the determining section G, the code generating section D, and the electronic! FIG. 2 is a circuit diagram showing a specific configuration of H.

In FIG. 4, the detection terminal 93 of the transmitting/receiving antenna B1 is connected to 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 a transistor 110. connected on the wiring.

A set voltage is applied from a terminal 103 via a resistor 102 to the inverting input terminal of the operational amplifier 100, and the operational amplifier 10
The output of 0 is connected to the inverter IC1 via the diode 104.
07 (for example, 74HCOO manufactured by TI). Note that the cathode side of the diode 1040 is grounded through a resistor 105 and a capacitor 106.

The output of the inverter IC107 is the inverter IC108
The signal is input to the input/output port (hereinafter referred to as I10 port) of the central processing unit (hereinafter referred to as CPU) 130 via the input/output port (hereinafter referred to as I10 port). Note that power for the operational amplifier 100 and the inverter ICs 107 and 108 described above is supplied through a terminal 6 directly connected to the battery 123. Further, the set voltage applied to the terminal 103 is set using the terminal (2) as a source.

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

The collector terminal of the transistor 110 is connected to an inverter IC 114 via a capacitor 113, and a resistor 1 is connected between the input and output of the inverter IC 114.
15 are provided. Note that the transistor 1 described above
10 and the inverter IC 114 are powered by a battery 123.
It is supplied from the terminal VCC via the transistor 120 connected to the terminal VCC.

A resistor 122 is provided between the emitter terminal and the base terminal of this transistor 120.
The base terminal of 20 is connected to the I10 port of the CPU 130 via a resistor 121. CPU130 is RAM
140, CPU 130 and RAM 140
is directly connected to the power supply 123 via the terminal vll.

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

In FIG. 4, an interrogation signal S1 from interrogator A (FIG. 1)
is transmitted, and when the transmitting/receiving antenna B1 receives the interrogation signal S1, the detection terminal 93 of the transmitting/receiving antenna B1
A power proportional to the received power is generated.

Then, the operational amplifier 100 compares the voltage level (detection level) generated at the detection terminal 93 with the set potential applied from the terminal 103, and if the detection level is higher than the set potential, the operational amplifier 100 Outputs a high level signal.

Therefore, a voltage obtained by subtracting the voltage drop across the diode 104 from the voltage of the high-level signal output from the operational amplifier is applied to the input terminal of the inverter IC 107.

Then, this inverter IC 107 judges the applied voltage as high level and sends a low level signal to the inverter IC 107.
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 sends the activation signal to the resistor 121 to make the transistor 120 conductive. It is output to transistor 120 via. As a result, the transistor 120 becomes conductive, and power is applied to the transistor 110 and the inverter TC114 at the terminal (2). Supplied via C.

Then, the transistor 110 and the inverter IC11
The circuit consisting of 4 operates as an amplifier circuit, amplifies a part of the interrogation signal S1 from the interrogator, and inputs it to the CPU 130.

The CPU 130 processes this input signal intermittently. For example, when writing movement data to transponder B, the movement data is written to RAM 140, and conversely,
When reading the movement data, the movement data written in the RAM 140 is read out and transmitted and received by the antenna B.
Modulator E of No. 1 is activated to transmit movement data to interrogator A (FIG. 1).

As described above, in the above embodiment, a part of the power of the received signal Sl is used for detection and the remaining power is used for modulation, so the antenna can be used for both transmission and reception. It is possible to downsize the device.

Further, the circuit section and the high frequency section can be easily separated by the feedthrough capacitor that blocks high frequency signals, and the modulation section can be designed compactly.

Furthermore, by providing a detector, the identification data is updated (RAM rewritten) according to the voltage level of the interrogation signal S1.
You can also do

In the transponder described above, when the interrogation signal S1 is not transmitted from the interrogator A (Fig. 1), even if the transmitting/receiving antenna B1 receives noise radio waves, the detection level is lower than the predetermined level. , the above-described determination unit G is not operated, thereby preventing malfunctions caused by noise radio waves or the like.

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

FIG. 5 is a circuit diagram showing the configuration of a modulation detection section in another embodiment. Note that the figure numbers in FIG. 5 that are the same as the figure numbers in FIG. 2 are equivalent to the figure numbers in FIG. 2.

The components of the transponder in this embodiment are all arranged on the same printed board, and as shown in FIG.
The stub 83 and the microstripe line 4 are arranged on the front surface of the printed board 95, and the other components are arranged on the back surface of the printed board 95, and the front and back surfaces are connected by through holes. Note that since the operation is the same as that of the above embodiment, the explanation will be omitted.

By configuring as shown in FIG. 5, further miniaturization can be realized.

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

FIG. 6 is a circuit diagram showing the configuration of a modulation detection section in still another embodiment. Note that the figure numbers in FIG. 6 that are the same as the figure numbers in FIG. 2 are equivalent to the figure numbers in FIG. 2.

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

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

With this setting, the interrogator will need two types of antennas to transmit right-handed circularly polarized waves and left-handed circularly polarized waves.
Since the right-handed circularly polarized wave having the power necessary for detection and the left-handed circularly polarized wave necessary for modulation can be individually set, the power of the received radio wave can be used more efficiently.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a circuit diagram showing a modulation detection section in the above embodiment, and FIG. 3 is a diagram for explaining the operation of the modulation detection section. Smith chart diagram, FIG. 4 is a circuit diagram showing the overall configuration excluding the modulation detection section in the above-mentioned one embodiment, FIG. 5 is a circuit diagram showing the modulation detection section in another embodiment, FIG. 7 is a circuit diagram showing a modulation detection section in another embodiment. B1... Transmitting/receiving antenna (antenna), D...
Code generation section (generation means), E... modulator (bias control means), F... detector (distribution means), G... judgment section (operation judgment means). Representative Patent Attorney Takashi Okabe (and 1 other person) Figure 2 Shin 3

Claims (1)

[Scope of Claims] A transponder of a mobile object identification device that receives, with an interrogator, a response radio wave containing identification information returned from a transponder attached to a mobile object, comprising: , an antenna for transmitting the response radio wave; an allocating means for distributing the power of the interrogation radio wave received by the antenna into first and second predetermined amounts of power according to a reflection coefficient of a detection element; an operation determining means for outputting a transmission command signal to transmit the response radio wave when it is determined that the voltage level of the first predetermined amount of power is equal to or higher than a predetermined level; When a signal is input, a generating means for generating the identification information stored in advance; and a bias amount of the detection element is changed according to the identification information outputted from the generation means, and the reflection of the detection element is changed. and bias control means for modulating the identification information into a reflected radio wave of the interrogation radio wave having the second predetermined amount of power by changing a coefficient according to the identification information, and returning it as the response radio wave. A transponder of a mobile object identification device characterized by: