JP2864543B2 - Transponder for mobile identification device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transponder used for an apparatus for identifying a mobile unit by exchanging an interrogator with a transponder attached to the mobile unit.

[Prior Art] A device for identifying a moving object of this type is used to sort a moving object such as a vehicle or a container, and radiates a radio wave from an interrogator to an area where the moving object may exist. Then, a configuration is adopted in which the moving object is identified by the response from the transponder.

Conventionally, as shown in FIG. 11, in such a transponder A, a unique identification code is set in a code generator A1 provided therein, and a radio wave (interrogation signal S1) from an interrogator B is transmitted to an antenna A2. , The whole or a part of the received radio wave is modulated by the modulator A3 using the identification code, and the radio wave (response signal S2) is radiated from the antenna A2 to the air again ( For example, “identification device” described in JP-A-57-79476). The response signal S2 from the transponder A is detected and identified by the interrogator B, so that the mobile body on which the transponder A is mounted is identified.

In addition, as shown in FIG. 11, as a transponder, it has an antenna A11 for detection, and an interrogation signal S1 transmitted from the interrogator B.
Is received by the antenna A11, the received signal is detected by the detector A12.
To the signal detector A13, and the signal detector A13 determines the received signal. When a desired received signal is obtained, the code generator
A configuration has been proposed in which the power supply of A1 is turned on to reduce the consumption of a built-in battery ("Microwave number identification device" described in Japanese Patent Application Laid-Open No. 53-142890).

[Problems to be Solved by the Invention] However, the former transponder (as exemplified in JP-A-57-79476) is replaced with the latter transponder (as exemplified in JP-A-53-142890). In order to reduce the consumption of the built-in battery by adding the configuration described above, the transponder needs at least two antennas for receiving radio waves from the interrogator, and there is a problem that the transponder becomes large.

This is because the antenna A2 in the former transponder is generally shared for transmission and reception, but separately from the antenna A11 for signal detection shown in the latter transponder.
Therefore, it is difficult to share both antennas A2 and A11. Because the detection antenna A11
The interrogator B received from the interrogator B is sent to the detector A12 and extracted as a low-frequency signal, and a carrier for transmitting the response signal S2 cannot be obtained. Separately, the interrogation signal S1 is received by the modulation antenna A2, the signal S1 is used as a carrier, and the modulator A3 performs modulation corresponding to the code from the code generation unit A4 to form a response signal S2. It is necessary to radiate into the air.

As a configuration that can be easily conceived to solve such a problem, there is a configuration in which the power received by one antenna is divided into two parts and sent to the detector A12 side and the modulator A3 side. However, in this configuration, the detector A12 and the modulator A3
, The power input to the device becomes small, and the distance that can be detected is shortened.

The transponder for a mobile object identification device of the present invention solves such a problem, and the transmission / reception antenna and the detection antenna are used in common, without shortening the identification detectable distance. It aims at miniaturization.

Configuration of the Invention [Means for Solving the Problems] In order to achieve the above object, the present invention has the following structures as means for solving the problems. That is,
The transponder for a mobile object identification device of the present invention receives a predetermined radio wave radiated from an interrogator and transmits internal identification information to the interrogator, as exemplified in the basic configuration diagram of FIG. Thereby, it is a transponder for a mobile object identification device capable of identifying the mobile object mounted thereon, one antenna for receiving a radio wave from the interrogator, and a radio wave received by the antenna Detecting means for detecting and outputting the detecting means; timing determining means for outputting an operation start signal in accordance with the detected signal output by the detecting means; and a transmission line between the antenna and the detecting means. A switching means for switching whether the radio wave received by the antenna is transmitted to the detection means side or reflected to the antenna side, and when an operation start signal is output by the timing determination means, Identification code generation means for supplying internal identification information to the switching means; and when the operation start signal is output by the timing determination means, the identification code generation means outputs the internal identification information to the switching means. To cause the switching means to perform switching in accordance with the supplied internal identification information, and transmit a reflected wave of the radio wave received by the antenna according to the internal identification information from the antenna. When the timing determination unit does not output the operation start signal, the switching unit transmits a radio wave received by the antenna to the detection unit side.

[Operation] In the mobile object identification transponder of the present invention configured as described above, when the antenna receives a radio wave from the interrogator, the detection means detects the radio wave and outputs a detection signal,
Timing determination means outputs an operation start signal according to the detection signal. When the timing determining means outputs the operation start signal, the identification code generating means supplies the internal identification information to the switching means, so that the switching means performs switching according to the supplied internal identification information. To cause the antenna to transmit a reflected wave of the radio wave received by the antenna according to the internal identification information. On the other hand, when the timing determination unit does not output the operation start signal, the switching unit transmits the radio wave received by the antenna to the detection unit. That is, the switching means functions as modulation means for modulating the interrogation signal.

Embodiment Hereinafter, a preferred embodiment of a transponder for a mobile object identification device according to the present invention will be described. FIG. 1 is a block diagram showing a configuration of a moving object identification device provided with a transponder as a first embodiment of the present invention.

The mobile object identification device includes an interrogator 1 as a fixed station installed on the ground, and a transponder 2 as a mobile station installed on a mobile object such as a vehicle or an article.

The transponder 2 receives a radio wave emitted from the interrogator 1 (hereinafter, also referred to as an interrogation signal S1), and recognizes the received radio wave as a unique internal identification representing the moving body on which the transponder 2 is installed. The information is modulated by an identification code (for example, an ID code) as information, and the modulated wave (hereinafter, also referred to as a response signal S2) is transmitted to the interrogator 1.

The interrogator 1 emits a radio wave in a predetermined direction, outputs a radio wave modulated as described above from a transponder 2 installed on a moving body passing a specific place, and receives the modulated radio wave. The identification code is demodulated to identify the mobile body on which the transponder 2 is mounted, and is composed of a transmission / reception antenna 3 and a transmission / reception device 4.

Hereinafter, the configuration of the transponder 2 which is the gist of the present invention will be described in detail.

The transponder 2 has a common antenna 11 for detection modulation including a microstrip slot antenna, a rectangular patch antenna, a dipole antenna, and the like.
The radio waves received at 11 are connected in series so that they are transmitted to a signal detector 14 as timing determination means via an RF switch unit 12 as switching means and a detector 13 as detection means, and A code generator 15 as identification code generation means is connected to the detector 14, and both are connected so that an output signal from the code generation unit 15 is input to the RF switch unit 12.

The detector 13 detects and demodulates an input signal, and includes an envelope detector, a synchronous detector, and the like.

The signal detector 14 outputs an operation start signal to the code generator 15 when the input signal from the detector 13 is at a level equal to or higher than a certain set value, and turns on the power to operate the code generator 15; Further, the operation of the code generator 15 is stopped at an arbitrary timing.

The code generator 15 generates a predetermined identification code.

The configuration of the signal detector 14 and the code generation unit 15 is
This will be described below with reference to FIG. 3 and FIG.

FIG. 2 shows a pre-processing part of the signal detector 14, and FIG. 3 shows a power control part and a code generator 15 of the signal detector 14.

The pre-processing portion of the signal detector 14 is composed of a comparator 21 and the like as shown in FIG. 2, and the output voltage of the comparator 21 is "1" when the voltage level applied to the input terminal 22 is higher than a certain set value. H level, and the input terminal 22
Is low when the voltage level applied to is lower than the set value, and this voltage signal is output from the output terminal 23. Therefore, when the transponder 2 does not receive the interrogation signal S1, the voltage level applied to the input terminal 22 is smaller than the predetermined value, so that the voltage level of the output terminal 23 remains at "L" level. When the interrogator 2 receives the interrogation signal S1, the voltage level applied to the input terminal 22 becomes higher than a predetermined value, so that the voltage level of the output terminal 23 becomes “H” level. When the interrogation signal S1 has data of a certain code string, the code string is sent to the input terminal 22 through the detector 13, is code-shaped by the comparator 21, and is sent to the output terminal 23.

Such a signal detector 14 is provided following the preprocessing section, and a control circuit shown in FIG. 3 is provided. As described above, this control circuit includes a power control part of the signal detector 14 and a code generation part 15.
And comprises an RS flip-flop 24, an AND circuit 25, a switch 26, a CPU 27, a ROM 28, a RAM 29, a clock generator 30, and the like.

The output of the RS flip-flop 24 is such that when the input S becomes “H”, the output Q becomes “H”, and even when the input S becomes “L”, the input R
Until the input R becomes “H”. When the input R becomes “H” and the Q becomes “L”, the input S becomes “H”.
The input S is connected to the input terminal 31 of this circuit, the input Q is connected to the output of the AND circuit 25, and the output Q is connected to the control terminal T of the switch 26. .

One input of the AND circuit 25 is an inverting input, and the inverting input terminal has an input terminal 31 and the other input terminals have a CPU 27.
OUT3 terminals are connected.

The switch 26 closes the contacts when the control terminal T is "H" to turn on the power of the power supply 32 to the CPU 27, and opens the contacts when the control terminal T is "L" to turn off the power of the CPU 27. Has both the basic function of the code generator 15 and the function of issuing a command to turn off the power of the signal detector 14. When the switch 26 is turned on and the power of the power supply 32 is turned on, the output OUT is output based on the identification code stored in the ROM 28 in advance.
Control the voltage level of 1. Also, the input IN signal is checked, and if the signal is a specific code string, the IN signal is written into the RAM 29, and the output OUT1 is output based on the written code string.
Can be controlled. The input IN is the input terminal 31 of the circuit, and the output OUT1 is the output terminal 33 of the circuit.
Connected to each other.

The ROM 28 stores programs and identification codes required by the CPU 27 in advance.

The RAM 29 is backed up by a backup power supply 34 and can always hold data, and various stored data can be rewritten under the control of the CPU 27.

The pull-down resistor 35 is a resistor connected to the output OUT3 of the CPU 27, and keeps the voltage level of the output OUT3 at “L” when the power of the CPU 27 is not turned on.

The operation of the circuit shown in FIG.
Next, a description will be given.

When the input terminal 31 becomes "H", the input S of the RS flip-flop 24 becomes "H", and the output Q thereof holds the information "H", the switch 26 is turned on, and the CPU 27 and the ROM 28, The power of the RAM 29 and the clock generator 30 is turned on. Then, the CPU 27 starts up, the program stored in the ROM 28 is executed, and the identification code stored in the ROM 28 is output to the RF switch unit 12, or the code string input from the input IN of the CPU 27 is stored in the RAM 29. The stored code string is output to the RF switch unit 12 as an identification code. Then, when a series of operations is completed, the output OUT3 is set to “H” after a predetermined time to turn off the power supply.

Next, the configuration of the RF switch unit 12 will be described. The RF switch unit 12 is a main line connecting the shared antenna 11 and the detector 13
In this configuration, a phase modulator 12b is connected in parallel with 12a.

The phase modulator 12b switches the impedance of the output terminal (connection terminal to the main line 12a) between "SHORT" and "OPEN" according to the level of the modulation code input from the code generation unit 15. Here, "SHORT" means zero or a value very low compared to the characteristic impedance of the main line 12a connecting the antenna 11 and the detector 13, and "OPEN" means infinity or the characteristic of the main line 12a. The value should be very high compared to the impedance. Here, the phase modulator 12b is set to be "OPEN" when the modulation code level is "L" and "SHORT" when it is "H".

The detailed configuration of the phase modulator 12b is as shown in FIG. The diode 42 is turned on or off according to the modulation code level of the output signal from the code generator 15 input from the input terminal 41.
This changes to FF, and the impedance of the output terminal 43 is switched between “SHORT” and “OPEN”. In the figure, the capacitor 44
Is for bypass, and the low-pass filter 45 is for setting the DC level of the main line 12a to OV.

The operation of the transponder 2 configured as described above will be described next.

First, the power received by the shared antenna 11 is
This section describes how to behave depending on the modulation code level of 12b.

When the modulation code level is "L", that is, when a signal of "L" is input from the code generator 15, the phase modulator 12b is "OPEN" when viewed from the connection with the main line 12a, so that the phase modulation is performed. This is the same as when the detector 12b is not connected, and all or almost all of the power received by the antenna 11 flows to the detector 13. In addition, the detector 13 absorbs all or almost all of the power that has flowed in order to increase the detection efficiency, and therefore does not re-radiate any or almost no radio waves from the antenna 11.

When the modulation code level is “H”, that is, when a “H” signal is input from the code generation unit 15, the phase modulator
Since 12b is “SHORT” when viewed from the connection with the main line 12a, the connection acts as a “SHORT” end, and the power received by the antenna 11 proceeds to the diode 42 and the capacitor 44, and most of the power thereafter is reflected. The light proceeds from the antenna 11 to the diode 44 and is re-emitted into the air.

The above operation is equivalent to transmitting the interrogator 1 from the interrogator 1 with amplitude modulation using the interrogation signal S1 as a carrier in accordance with the modulation code level when the transponder 2 is viewed from the interrogator 1.
The response signal S2 can be transmitted from the transponder 2 to the interrogator 1 simply by directly transmitting the code from the code generator 15 to the input terminal 41 of b.

Next, how the responder 2 performs data communication with the interrogator 1 will be described.

First, when the transponder 2 does not receive the interrogation signal S1, the code generator 15 is turned off and is inactive, but at this time, the modulation code transmitted from the code generator 15 to the phase modulator 12b. The level is set in advance to be “L”. Therefore, at the same time as receiving the interrogation signal S1, the signal is sent from the shared antenna 11 to the detector 13 and further sent to the signal detector 15, and when the signal has a voltage level equal to or higher than the set value, the signal detector 14 The power of the code generator 15 is turned on.
When the power is turned on, the code generator 15 controls the phase modulator 12b to enter a transmission state. In this transmission state, by controlling the modulation code level output to the phase modulator 12b based on the identification code stored in the ROM 28, a response signal to the interrogator 1 that has been subjected to the amplitude modulation based on the identification code described above.
S2 is transmitted. When the transmission of the response signal S2 is completed, the modulation code level is fixed to "L" again to enter the reception state, and thereafter, reception and transmission are switched as required.
Thereafter, when a series of necessary transmission / reception is completed (for example, after a predetermined number of times have elapsed), the power of the code generation unit 15 is turned off, and the transponder 2 is set to a receivable state.

By the above operation, in the transponder 2, the RF switch unit 12 connects the detector 13 to the shared antenna 11 only when necessary, and otherwise, the RF switch unit 12 operates as one amplitude modulator. That is, the transponder 2 performs detection and modulation in a time-division manner.

With such an operation, the transponder 2 according to the present embodiment utilizes all the power obtained by the shared antenna 11,
Two antennas for detection and modulation can be shared.

Therefore, according to the transponder 2 of the present embodiment, it is possible to reduce the size of the apparatus without shortening the detectable distance. When two antennas are used, it is conceivable that they adversely affect the directivity of the antennas, but such adverse effects can be eliminated.

Note that, as another aspect of the first embodiment, the phase modulator 12
As shown in FIG. 5, the configuration of b
The load conversion circuit 52 may be connected to 1 and the impedance of the output terminal 54 may be changed using the change in the capacitance of the diode 51 due to the change in the reverse bias voltage applied to the modulation code input terminal 53. The same effects as in the embodiment can be obtained. The load conversion circuit 52 is configured by a combination of a transmission line such as a microstrip line and a stub, a capacitor, an inductor, and the like.

 Next, a second embodiment of the present invention will be described.

FIG. 6 is a block diagram showing a configuration of a transponder according to a second embodiment.

As shown in FIG. 6, the transponder 60 includes a shared antenna 61, a detector 62, a signal detector 63, and a code generator 64 having the same configuration as in the first embodiment, and an RF switch having a different configuration from the first embodiment. And a part 65.

The RF switch unit 65 has a configuration in which two phase modulators 67 and 68 are arranged in a π shape on both sides of a transmission line 66, and the transmission line 66 is made of, for example, a microstrip line or a coaxial line. The length is π / 2 phase length, ie, 1 effective wavelength. Further, the phase modulators 67 and 68 are exactly the same as the phase modulator 12b of the first embodiment.

Note that the code generator 64 has the same configuration as the code generator 15 of the first embodiment, but the input to the second phase modulator 68 is CP
The signal from the output terminal OUT2 (FIG. 2) of U is input.

Next, the operation of the transponder 60 configured as described above will be described.

Assuming that the modulation code levels applied to the phase modulators 67 and 68 are L1 and L2, respectively, when L1 = "L", the impedance of the phase modulator 67 viewed from the connection point P1 between the transmission line 66 and the phase modulator 67. Is "OPEN", and almost all of the power received by the antenna 61 flows into the transmission line 66.

On the other hand, when L2 = “L”, the phase modulator 68 is “OPEN” when viewed from the connection point P2 between the transmission line 66 and the phase modulator 68, and most of the power flows to the detector 62 and is absorbed there. . Therefore, no or little radio waves are re-emitted from the antenna 61. Conversely, when L = 2 “H”, the connection point P2 is “SH
The impedance becomes "OPEN" when viewed from the connection point P1 separated by π / 2 phase length, so that the connection point P1 re-radiates the radio wave from the antenna 61 as the "OPEN" end.

When L1 = “H”, the power received by the antenna 61 is re-emitted from the antenna 61 with the connection point P1 as the “SHORT” end.

The above operation is as follows. When the responder 60 is viewed from an interrogator (not shown), the radio wave is absorbed by the detector 62 when L1 = L2 = “L”; otherwise, the interrogation signal is transmitted by the RF switch 65 according to the modulation code. 180 for “OPEN” and “SHORT” as carrier
This is equivalent to transmitting with phase modulation of ゜.

Next, how the transponder 60 performs data communication with the interrogator will be described.

When the transponder 60 has not received the interrogation signal, the power of the code generator 64 is off. At this time, L1 = L2 = "L"
Set to fix to. Then, at the same time when the power of the code generator 64 is turned on, the detector 62 is cut off at a high frequency by setting L2 = “H”, and L1 is switched between “L” and “H” to transmit a response signal. When the transmission is completed, the code generator 64
Turn off the power and fix L1 = L2 = "L" again.
The received signal at 61 flows into the detector 62.

With the above operation, in the transponder 60, the RF switch unit 65 connects the detector 62 to the antenna 61 only when necessary, and otherwise, the RF switch unit 65 operates as one phase modulator. With such operations, the transponder 60 according to the present embodiment is
By utilizing all the power obtained by the shared antenna 61, the two antennas for detection and modulation can be shared, and therefore, the same effects as in the first embodiment can be obtained.

 Next, a third embodiment of the present invention will be described.

FIG. 7 is a block diagram showing a configuration of a transponder according to a third embodiment.

As shown in FIG. 7, the transponder 70 includes a shared antenna 71, a detector 72, a signal detector 73, and a code generator 74 having the same configuration as the first embodiment, and an RF switch having a different configuration from the first embodiment. And a unit 75.

The RF switch unit 75 outputs “OPEN” when the signal level applied to the control input terminal is “L” and “SHORT” when the signal level is “H”.
In addition, it can be switched to "THRU" when "M".
Here, “THRU” means that all or most of the power passes at both ends of the RF switch unit 75.

The RF switch unit 75, as shown in FIG.
It is composed of two diodes 81 and 82 and a low-pass filter 83. The two diodes 81 and 82 have different signal levels to be turned on. When the signal level is “M”, the diode 81 is turned on but the diode 82 remains off. Here, when the signal level (hereinafter, LCON) applied to the control input terminal 84 is “L”, the diodes 81 and 82 are both off, and the input impedance of the terminal 85 is “OPEN”. When LCON = "M",
Diode 81 is on, diode 82 is off, and terminal
85 is connected only to terminal 86 and becomes "THRU". LCON =
When "H", the diodes 81 and 82 are both turned on, the terminal 85 is connected to both the terminal B86 and the ground, and its input impedance becomes "SHORT". The low-pass filter 83 is for setting the DC level to OV.

Next, the operation of the transponder 70 configured as described above will be described.

When LCON = “L”, the impedance of the RF switch unit 75 is “OPEN”, and the power received by the antenna 71 is re-emitted from the antenna 71 as the “OPEN” end.

When LCON = “M”, the RF switch unit 75 is “THRU”, and the antenna 71 and the detector 72 are directly connected. Therefore, almost all of the power received by the antenna 71 flows to the detector 72, where it is absorbed. Therefore, the antenna 71 hardly re-radiates radio waves.

When LCON = “H”, the impedance of the RF switch unit 75 is “SHORT”, and the power received by the antenna 71 is re-emitted from the antenna 71 as the “SHORT” end.

The above operation is as follows. When the transponder 70 is viewed from an interrogator (not shown), the radio wave is absorbed by the detector 72 when LCON = “M”, and the modulation code level (“L” or “H” Level) according to the interrogation signal as carrier 180
This is equivalent to transmitting with phase modulation of ゜.

Next, how the transponder 70 performs data communication with the interrogator will be described.

When the transponder 70 does not receive the interrogation signal, the power of the code generator 74 is off, and at this time, LCON is set to be fixed at "M". Then, when the power is turned on, the code generation unit 74 sends an identification code to the input terminal 84 of the RF switch unit 75, transmits a response signal, and when the transmission is completed, turns off the power of the code generation unit 74 and again. As LCON = “M”, the received signal of the antenna 71 is caused to flow into the detector 72.

Therefore, the embodiment 70 has the same effect as the first embodiment.

 Next, a fourth embodiment of the present invention will be described.

FIG. 9 is a block diagram showing a configuration of a transponder as a fourth embodiment.

As shown in FIG. 9, the transponder 90 includes a shared antenna 91, a detector 92, a signal detector 93, and a code generator 94 having the same configuration as in the first embodiment, and an RF switch having a different configuration from the first embodiment. And a unit 95. Note that the code generator 94 is configured to output a signal also from the output terminal OUT2 of the CPU, as in the second embodiment.

The RF switch unit 95 has a configuration in which an RF switch 96, a transmission line 97, and an RF switch 98 are connected in series. The transmission line
97 is the same as that of the second embodiment, and the RF switch 9
6,98 are connected or disconnected according to the signal level applied to the control input terminal, and the signal level is "H"
, And open when “L”.

As shown in FIG. 10, the RF switches 96 and 98 are composed of a diode 100, a capacitor 101, and a low-pass filter.
The diode 100 changes between ON and OFF depending on the signal level applied to the control input terminal 103, and the terminal 104 and the terminal 105
Is connected or disconnected. Also the capacitor
101 is for RF bypass, and the low-pass filter 102 is for setting the DC level to OV.

Next, the operation of the transponder 90 configured as described above will be described.

Assuming that the modulation code levels applied to the RF switches 96 and 98 are L1 and L2, respectively, when L1 = "H", the antenna 91 and the transmission line 97 are connected by the RF switch 96. Here, when L2 = “H”, the transmission line 97 and the detector 92 are connected by the RF switch 98, and all or almost all of the power received by the antenna 91 flows to the detector 92, where it is absorbed. You. Therefore, the transponder 90 hardly emits radio waves.

Conversely, when L2 = "L", the RF switch 98 is open.
When this is viewed from the RF switch 96 side separated by π / 2 phase length, the impedance becomes “SHORT”. Therefore, the RF switch 96 re-radiates from the antenna 91 as a “SHORT” end.

When L1 = "L", the RF switch 96 is "OPEN", nothing is connected to the antenna 91, and the power received there is
It is re-emitted from the antenna 91.

The above operation is performed when L1 =
When L2 = “H”, the detector 72 absorbs the radio wave, and otherwise, it is equivalent to transmitting the query signal as a carrier with a 180 ° phase modulation according to the modulation code.

The operation of the transponder 90 configured as described above is the same as the operation of the transponder 60 of the second embodiment. Therefore, the transponder 90 of the present embodiment is different from the transponders of the first and second embodiments. A similar effect is achieved.

Although several embodiments of the present invention have been described above,
The present invention is not limited to such an embodiment at all. For example, in the present embodiment, the power of the code generator is turned on when the detected radio wave has a signal level higher than a certain set value. However, instead of this, it is possible to implement in various modes without departing from the gist of the present invention, such as a configuration in which the power of the code generator is turned on only when the detected radio wave has a specific pattern. Of course.

Effect of the Invention As described in detail above, in the transponder for mobile object identification of the present invention, when the antenna receives a radio wave from the interstitial device,
The detection means detects the radio wave and outputs a detection signal, and the timing determination means outputs an operation start signal according to the detection signal. When the timing determining means outputs the operation start signal, the identification code generating means supplies the internal identification information to the switching means, so that the switching means performs switching according to the supplied internal identification information. The radio wave received by the antenna,
The reflected wave according to the internal identification information is transmitted from the antenna. On the other hand, when the timing determination unit does not output the operation start signal, the switching unit transmits the radio wave received by the antenna to the detection unit.

Thus, in the present invention, when the antenna is not receiving the radio wave from the interrogator, it is configured to detect the radio wave received by the antenna, and when the radio wave from the interrogator is received and detected, By switching according to the internal identification information, the radio wave from the interrogator is modulated according to the internal identification signal and transmitted from the received antenna. That is, according to the present invention, detection and modulation can be performed with a single antenna without shortening the identification detection distance, and the size of the device can be reduced. Also, since two antennas are not used, the device has excellent antenna directivity.

[Brief description of the drawings]

1 to 4 show a first embodiment of the present invention.
FIG. 1 is a block diagram showing the configuration of a moving object identification device provided with a transponder as a first embodiment, FIG. 2 is a circuit diagram showing a preprocessing portion of a signal detector, and FIG. 3 is a power supply of the signal detector. FIG. 4 is a circuit diagram showing a phase modulator, FIG. 5 is a circuit diagram showing a phase modulator of another embodiment of the first embodiment, and FIG. 6 is a circuit diagram showing a phase modulator of the first embodiment. FIG. 7 is a block diagram showing a configuration of a transponder as an embodiment, FIG. 7 is a block diagram showing a configuration of a transponder as a third embodiment, FIG. 8 is a circuit diagram showing an RF switch unit of the third embodiment, FIG. 9 is a block diagram showing the configuration of a transponder as a fourth embodiment, and FIG.
FIG. 11 is a circuit diagram showing an RF switch according to an embodiment, and FIG. 11 is a block diagram showing a configuration of a conventional moving object identification device. 1 Interrogator 2,60,70,90 Transponder 11,61,71,91 Common antenna 12,65,75,95 RF switch unit 13,62,72,92 Detector 14,63,73,93 …… Signal detector 15,64,74,94 …… Code generator 12b, 67,68 …… Phase modulator 66,97 …… Transmission line 96,98 …… RF switch

Claims (1)

(57) [Claims] 1. A mobile object identification device for receiving a predetermined radio wave radiated from an interrogator and transmitting internal identification information to the interrogator, thereby enabling identification of a mobile object mounted therein. A transponder, one antenna for receiving a radio wave from the interrogator, a detecting unit for detecting a radio wave received by the antenna and outputting a detection signal, and a detecting unit output by the detecting unit Timing determining means for outputting an operation start signal in accordance with the signal, provided on a transmission line between the antenna and the detecting means, and transmitting a radio wave received by the antenna to the detecting means side Switching means for switching whether to reflect to the antenna side, and an identification code generator for supplying the internal identification information to the switching means when an operation start signal is output by the timing determination means. And wherein when the operation start signal is output by the timing determination means, the identification code generation means supplies the internal identification information to the switching means, so that the internal identification information is supplied to the switching means. The switching according to the internal identification information, the reflected wave of the radio wave received by the antenna is transmitted from the antenna according to the internal identification information, and the operation start signal is output by the timing determination unit. When not, the switching means transmits a radio wave received by the antenna to the detection means side, the transponder for identifying a moving body.