JPH06334565A - Transponder for moving object discriminating device - Google Patents

Abstract

PURPOSE:To provide the transponder for the moving object discriminating device which solves the problem that the energy wave of a linear polarized wave can not be received when the attitude of the transponder for the moving object discriminating device receiving the microwave of the linear polarized wave becomes different from the plane of polarization of a radiated radio wave. CONSTITUTION:Diode switches 3a and 3b which are used in common to a discrimination signal sending circuit 6 for detection are mounted on each of horizontal and vertical sides of radiation elements of a microstrip patch antenna 2 for linear polarization and the diodes 3a and 3b for detection and discrimination signal transmission are switched and used automatically by a changeover switch 5 even when the attitude of the transponder is rotated by 90 deg., thereby enabling stable operation irrelevantly to the horizontal and vertical directions of the attitude of the transponder.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transponder for a mobile identification device, which receives a predetermined radio wave radiated from an interrogator by linear polarization and responds to the interrogator with a signal corresponding to an identification code. is there.

[0002]

2. Description of the Related Art In recent years, a response device has been carried by a person or attached to a moving body, and appropriate information and the like has been stored in this response device. The response device that transmitted and received and demodulated this interrogation signal returns an appropriate response signal to the interrogation device by microwave,
For the interrogator, a system has been proposed in which a demodulation response signal received and demodulated is compared with an appropriate means to identify a person or a moving body.

A conventional transponder for a moving body identifying apparatus will be described below. If driving power is supplied from a commercial AC power source or a built-in battery when the transponder functions as an ID card, sufficient miniaturization and life of the transponder cannot be obtained. Therefore, a technique in which the electric power of the radiated radio wave is used as a drive power source from an external interrogator to a responder is disclosed in Japanese Patent Laid-Open No. 63-54023. The outline of the transponder shown here is
As shown in FIG. 7, 1 / wavelength of the interrogation signal on the substrate 13
Microstrip line 12 selected as length 2
The radiation element 14 is metallized to form an antenna, which is rectified by the diode 15a and the response signal is added to the diode 15b to transmit the response signal.

[0004]

However, in the above-mentioned conventional configuration, since the microwave is transmitted as the linearly polarized wave, if the attitude of the transponder is not the same as the plane of polarization of the radio wave radiated from the interrogator, the linearly polarized wave is generated. There is a problem that the energy wave of the wave cannot be received. In other words, since the mounting direction of the transponder is limited, it is necessary to take measures such as indicating the mounting direction or making a rectangular shape so that the mounting direction is correct, and the attitude of the transponder was changed after mounting. There was a problem that it would not work.

The present invention is to solve the above-mentioned problems of the prior art. By sharing the diode for the detection and the identification signal transmission circuit, the attitude of the transponder can be set horizontally relative to the radio wave from the interrogator. An object of the present invention is to provide a transponder for a moving object identifying device, which can obtain stable DC power for an identifying signal transmitting circuit in either of the vertical directions.

[0006]

In order to achieve this object, the present invention provides a detection circuit and an identification signal transmission circuit for each side of a radiating element of a linearly polarized microstrip patch antenna in the horizontal and vertical directions. A diode that is shared with the interrogator is installed, and power is supplied to the identification signal transmission circuit by the voltage detected by the diode installed at the feeding point of the radiating element of the microstrip patch antenna on the same polarization plane as the radio wave radiated from the interrogator. And use the other diode for the identification signal sending circuit. When the attitude of the transponder is rotated by 90 degrees, the switching means automatically switches the diode used for detection for the identification signal transmission circuit and the diode used for the identification signal transmission circuit for detection.
In this way, stable DC power can be provided to the identification signal generating circuit regardless of the horizontal and vertical directions.

Further, a diode for detection is attached to each of the horizontal and vertical sides of the radiating element of the microstrip patch antenna, and a diode for an identification signal transmission circuit is attached to the other two sides.
A voltage is detected by one of the detection diodes to supply power to the identification signal transmission circuit, and one of the other two diodes is used for the identification signal transmission circuit so that switching means is not required. May be.

Further, in addition to the diode, two diodes may be attached to the same end of the microstrip patch antenna with the anode and the cathode reversed to increase the output voltage.

Further, the dependency on the received electric field strength may be adjusted by combining the diodes mounted at the respective ends with those having different forward voltage characteristics.

Further, the linearly polarized microstrip patch antenna is formed in a circular shape instead of a rectangular shape, and feeding points are provided at two points or four points with a central angle shifted by 90 degrees, and diodes are mounted. Is also good.

Further, the number of the microstrip patch antennas is two, a feeding point is provided on each side of the first microstrip patch antenna in the horizontal direction and in the vertical direction of the second microstrip patch antenna, and a diode is mounted. It may be configured to do so.

The first and second microstrip patch antennas may have a trapezoidal shape instead of a square shape, and a feeding point may be provided on the bottom bottom of the trapezoidal shape to mount a diode.

Also, predetermined radio waves are transmitted from the interrogator in vertical and horizontal polarizations with different output powers, DC power is obtained from the radio waves having a high output power, and the radio waves having a low output power are transmitted. Alternatively, the identification signal may be returned.

The radio wave transmitted from the interrogator may be circularly polarized.

[0015]

The present invention makes it possible to perform a stable response operation regardless of the horizontal or vertical orientation of the attitude of the transponder by sharing the diode of the detector for supplying DC power and the diode for the identification signal transmitting circuit. , In the case of installing multiple interrogators, it is possible to respond to those with different polarization planes of transmission and reception in order to prevent interference between the interrogators. Furthermore, the dependency on the received electric field strength can be adjusted by combining with diodes having different forward voltage characteristics. Further, by using a plurality of patch antennas, it is possible to eliminate interference between feeding points, and by making the shape of the patch antenna trapezoidal, size reduction can be achieved.

[0016]

(Embodiment 1) Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.

The transponder for the moving body identifying apparatus of FIG.
One side formed above is about 1 / wavelength of the radio wave from the interrogator
2 includes a linearly polarized square microstrip patch antenna 2, a diode 3a, 3b, a coil L and a capacitive element C.
The low-pass filters 4a and 4b composed of
The changeover switch 5 and the identification signal generating circuit 6 are provided between them. FIG. 2 shows the details of the changeover switch 5. FIG. 2A shows a circuit connection method (internal view) of the changeover switch 5, and FIG. 2B shows a configuration for automatic changeover (front view). ) Is shown. That is, FIG.
In the configuration for automatic switching of the switch, a metal ball 7 that can move along the groove 8 is provided in the groove 8.
Is provided. The change-over switch 5 installed on the board 1 depends on the installation state of the board 1 and the ball 7 is moved by its own weight.
Moves to the side a or the side b shown in FIG. By this movement of the ball 7, the circuit connection shown in FIG. 2A is switched to the a side or the b side by a mechanical method not shown.

For the transponder having the above-mentioned structure, a predetermined radio wave is radiated by the linearly polarized wave from the interrogator. The reception polarization plane of the microstrip patch antenna 2 in the transponder becomes Pv or Ph depending on the attitude of the transponder.
When the polarization plane of the received radio wave is vertical (Pv), the changeover switch 5 is on the a side, is rectified by the diode 3a, and the DC power obtained by passing through the low-pass filter 4a is the identification signal generating circuit 6 Is supplied to. And
By applying the signal generated by the identification signal generating circuit 6 to the diode 3b, the identification signal is transmitted on another polarization plane (Ph).

On the other hand, when the attitude of the transponder is rotated by 90 degrees, the changeover switch 5 is switched to the b side, the received radio wave (plane of polarization Ph) is rectified by the diode 3b, and passed through the low pass filter 4b. The obtained DC power is supplied to the identification signal generating circuit 6. Then, the identification signal is transmitted on another polarization plane (Pv) by applying the signal generated by the identification signal generation circuit 6 to the diode 3a.

As described above, in the transponder for a moving body identifying apparatus of this embodiment, stable DC power can be obtained regardless of the orientation of the transponder in the horizontal and vertical directions.

(Second Embodiment) A second embodiment of the present invention will be described below with reference to FIG.

3 is different from FIG. 1 in that the number of diodes 3 is increased and diodes 3a to 3d are provided, and the changeover switch 5 in FIG. 1 is not necessary.

The structure is similar to that of the first embodiment, except that the linearly polarized microstrip patch antenna 2 has diodes 3a to 3d.
Is mounted, and the identification signal generating circuit 6 is inserted between them. The capacitive element C7 is for DC cutting and the coil L8.
Is for DC feedback.

In the above structure, when the polarization plane of the received radio wave is vertical (Pv), it is rectified by the diode 3a,
The DC power obtained by passing through the low pass filter 4 is supplied to the identification signal generating circuit 6. Then, the identification signal generated by the identification signal generation circuit 6 is applied to the diode 3c to transmit the identification signal on another polarization plane (Ph). Although the identification signal of the plane of polarization (Pv) is actually transmitted through the diode 3d, there is no problem because only the plane of polarization (Ph) is accepted on the interrogator side.

On the other hand, when the attitude of the transponder is rotated by 90 degrees, the received radio wave (plane of polarization Ph) is rectified by the diode 3b and the DC power obtained by passing it through the low pass filter 4 is an identification signal. It is supplied to the generation circuit 6. Then, the identification signal generated by the identification signal generation circuit 6 is applied to the diode 3d, so that the identification signal is changed to another polarization plane (P
Send in v). Although the identification signal of the polarization plane (Ph) is actually transmitted through the diode 3c, there is no problem because only the polarization plane (Pv) is accepted on the interrogator side.

As described above, in the moving body identifying device responder of the present embodiment, stable DC power can be obtained irrespective of the horizontal and vertical orientations of the posture of the responder without the need for a changeover switch.

(Embodiment 3) A third embodiment of the present invention will be described below with reference to FIG.

4 is different from FIG. 1 in that the number of diodes 3 is increased and the diodes 3e to 3h are used to perform voltage doubler rectification.

That is, in this configuration, two sets of two diodes 3e to 3h are mounted on the microstrip patch antenna 2 for linearly polarized waves similar to those of the first embodiment, two diodes 3e to 3h being cathodes and two anodes are reversed, and the changeover switch 5 is provided therebetween. And the identification signal generating circuit 6 is included.

The received radio wave has a vertical polarization plane (P
In the case of v), the DC power that is rectified by the diodes 3e and 3f and doubled by passing through the low pass filter 4a is supplied to the identification signal generating circuit 6. Then, the signals generated by the identification signal generating circuit 6 are supplied to the diodes 3g, 3h.
To transmit the identification signal in another polarization plane (Ph).

On the other hand, when the posture of the transponder is rotated by 90 degrees, the received radio wave (polarization plane Ph) is rectified by 3g and 3h, and the DC power is double-voltage rectified by passing through the low pass filter 4b. Are switched by the changeover switch 5 and supplied to the identification signal generating circuit 6. Then, the signals generated by the identification signal generation circuit 6 are transferred to the diodes 3e, 3f.
To transmit the identification signal in another polarization plane (Pv).

As described above, in the transponder for a moving body identifying apparatus of this embodiment, stable DC power can be obtained regardless of the orientation of the transponder in the horizontal and vertical directions, and the diode arranged in the opposite direction. Double voltage is obtained by 3e to 3h.

(Embodiment 4) A fourth embodiment of the present invention will be described below with reference to FIGS.

The fourth embodiment is different from the third embodiment in that diodes 3a to 3d having different forward voltage characteristics are used to adjust the dependency on the received electric field strength.

Specifically, as shown in FIG. 4, by combining a diode A having a good forward voltage characteristic in a weak electric field and a diode B having a good forward voltage characteristic in a strong electric field, the dependency on the received electric field strength can be arbitrarily set. Can be adjusted.

The structure is similar to that of the third embodiment, in which a linearly polarized microstrip patch antenna 2 is provided with two sets of diodes 3a to 3d having different forward voltage characteristics, two sets of cathodes and two sets of anodes in reverse, and in between. It includes a changeover switch 5 and an identification signal generating circuit 6.

As described above, in the transponder for a moving body identifying apparatus of this embodiment, stable DC power can be obtained regardless of the orientation of the transponder in the horizontal and vertical directions, and the diode arranged in the opposite direction. Double voltage is obtained by 2a to 2d,
In addition, the dependence on the received electric field strength can be adjusted.

(Fifth Embodiment) A fifth embodiment of the present invention will be described below with reference to FIG.

In FIG. 6, the difference from FIG. 1 is that the number of linearly polarized microstrip patch antennas 2 is increased and microstrip patch antennas 2a and 2b are provided to improve isolation between feed points in the vertical and horizontal directions in FIG. There is a point.

The transponder for the moving body identifying apparatus shown in FIG.
One side formed above is about 1 / wavelength of the radio wave from the interrogator
The low-pass filters 4a and 4b composed of the diodes 3a and 3b, the coil L, and the capacitive element C are mounted on the linearly polarized square microstrip patch antennas 2a and 2b, and the changeover switch 5 is identified therebetween. The signal generating circuit 6 is provided.

To the transponder having the above-mentioned structure, the interrogator radiates a predetermined radio wave as a linearly polarized wave. Microstrip patch antennas 2a and 2b in the transponder
The received polarization plane at Pv or Ph depends on the attitude of the transponder.
Becomes When the polarization plane of the received radio wave is vertical (Pv), the changeover switch 5 is on the a side, and the diode 3
The DC power rectified by a and obtained by passing through the low-pass filter 4a is supplied to the identification signal generating circuit 6.
Then, by adding the signal generated by the identification signal generation circuit 6 to the diode 3b, the identification signal is changed to another polarization plane (P
Send in h).

On the other hand, when the attitude of the transponder is rotated by 90 degrees, the selector switch 5 is switched to the b side, the received radio wave (plane of polarization Ph) is rectified by the diode 3b, and passed through the low pass filter 4b. The obtained DC power is supplied to the identification signal generating circuit 6. Then, the identification signal is transmitted on another polarization plane (Pv) by applying the signal generated by the identification signal generation circuit 6 to the diode 3a.

As described above, in the transponder for a moving body identifying apparatus of this embodiment, stable DC power can be obtained regardless of the orientation of the transponder in the horizontal and vertical directions, and the microstrip patch antennas 2a, 2b are provided. Since there are two, it is not necessary to consider the isolation between the feeding points.

The linearly polarized microstrip patch antenna 2 according to the first, second, third and fourth embodiments.
The shape may be circular instead of rectangular, and the feeding points may be provided at two or four points with the central angle shifted by 90 degrees, and the diode may be mounted.

The linearly polarized microstrip patch antennas 2a and 2b in the fifth embodiment are not trapezoidal but trapezoidal, and the feeding point is provided on the lower bottom of each trapezoid and the diode is mounted. May be.

As a method of transmitting the identification signal in the first, second, third, fourth and fifth embodiments, vertical and horizontal radio waves with different output powers are transmitted from the interrogator to determine the output power. The identification signal may be returned by obtaining DC power from a radio wave having a large polarization plane and changing the reflectance of the radio wave on a polarization plane having a small output power.

In the first, second, third, fourth, and fifth embodiments, the interrogator transmits a radio wave as a circularly polarized wave, and the DC power is supplied in either the horizontal or vertical polarization plane. Then, the identification signal may be transmitted by changing the reflectance of the radio wave on the other polarization plane.

[0048]

INDUSTRIAL APPLICABILITY As described above, the transponder for a moving body identifying apparatus of the present invention can obtain stable DC power regardless of the orientation of the transponder in the horizontal and vertical directions, and a plurality of interrogators are installed. In some cases, in order to prevent interference between interrogators, it is possible to respond to transmission and reception with different polarization planes. Furthermore, the dependency on the received electric field strength can be adjusted by combining with diodes having different forward voltage characteristics. Further, by using a plurality of patch antennas, it is possible to eliminate interference between feeding points, and by making the shape of the patch antenna trapezoidal, size reduction can be achieved.

[Brief description of drawings]

FIG. 1 is a plan view of a main part of a transponder for a moving body identifying apparatus according to a first embodiment of the present invention.

FIG. 2 is a plan view of a changeover switch, which is a main part of the transponder for the same moving body identifying apparatus.

FIG. 3 is a plan view of a main part of a transponder for a moving body identifying apparatus according to a second embodiment of the present invention.

FIG. 4 is a plan view of a main part of a transponder for a moving body identifying apparatus according to third and fourth embodiments of the present invention.

FIG. 5 is a characteristic diagram of an input electric field and a detection voltage of a diode used in a fourth embodiment of the present invention.

FIG. 6 is a plan view of a main part of a transponder for a moving body identifying apparatus according to a fifth embodiment of the present invention.

FIG. 7 is a plan view of a main part of a conventional transponder for a moving body identifying device.

[Explanation of symbols]

 1 Substrate 2 Microstrip Patch Antenna 3 Diode 4 Low Pass Filter 5 Changeover Switch 6 Identification Signal Generation Circuit 7 Capacitance Element C 8 Coil L 9 Feed Point 10 Identification Signal Input Terminal 11 Power Supply Voltage Output Terminal 12 Microstripline 13 Board 14 Radiation Element 15 diode

Claims (9)

[Claims] 1. A microstrip patch antenna for receiving a predetermined radio wave radiated in a vertically or horizontally polarized wave from an interrogator, and a radiating element of the microstrip patch antenna, which is connected to each one side in the horizontal and vertical directions. Power is supplied from the first and second diodes and one of the first and second diodes through the first terminal, and the identification signal is sent to the other diode through the second terminal. An identification signal transmission circuit for radiating radio waves from the microstrip patch antenna horizontally or vertically.
Depending on its own posture, one of the first and second diodes is switched from the first terminal to the second terminal, and the other is connected from the second terminal to the first terminal. A transponder for a moving body identification device, which has switching means for switching to. 2. A microstrip patch antenna for receiving a predetermined radio wave radiated in a vertical or horizontal polarization from an interrogator, and a radiating element of the microstrip patch antenna connected to each side in the horizontal and vertical directions. The first and second diodes, and the third and fourth diodes connected to the remaining sides in the horizontal and vertical directions of the radiating element of the microstrip patch antenna, which face the first and second diodes. Power is supplied from a diode and one of the first and second diodes, and an identification signal is sent out through the third and fourth diodes to generate horizontal or vertical polarization from the microstrip patch antenna. A transponder for a mobile body identification device, which has an identification signal transmission circuit for emitting radio waves. 3. A fifth voltage and a sixth diode, in which the anode and the cathode of the first diode and the second diode are reversed, are provided for each of the first diode and the second diode, and a voltage doubler is provided for power supply. The transponder for a mobile body identification device according to claim 1. 4. A response for a mobile body identifying apparatus according to claim 3, wherein fifth and sixth diodes having forward voltage characteristics different from those of the first and second diodes are provided to adjust the dependence on the received electric field strength. vessel. 5. A microstrip patch antenna having a circular shape instead of a rectangular shape, and feeding points are provided at two or four points with a central angle shifted by 90 degrees, and each diode is mounted. The transponder for a mobile body identification device according to any one of the above. 6. A first microstrip patch antenna for receiving a predetermined radio wave radiated from an interrogator in vertical polarization, and a second microstrip patch antenna for receiving a predetermined radio wave radiated in horizontal polarization. A first and a second diode connected to each one side of the radiating element of the microstrip patch antenna in the horizontal and vertical directions, and from one of the first and second diodes via a first terminal An identification signal transmitting circuit which receives an electric power supply and transmits an identification signal to the other diode through the second terminal to radiate a radio wave from the microstrip patch antenna in horizontal or vertical polarization, and in its own posture Accordingly, one connection of the first diode and the second diode is switched from the first terminal to the second terminal, and the other connection is connected from the second terminal. A transponder for a moving body identifying device, comprising: a switching unit that switches to the first terminal. 7. The transponder for a moving body identifying apparatus according to claim 6, wherein the first and second microstrip patch antennas are trapezoidal instead of rectangular. 8. The transponder for a mobile body identification device according to claim 1, wherein the interrogator transmits predetermined radio waves by vertically and horizontally polarized waves with different output powers. 9. The transponder for a mobile body identification device according to claim 1, wherein a predetermined radio wave is transmitted from the interrogator by circular polarization.