JP2840832B2 - Reflective transmitter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflection type transmission device, and is particularly suitable for use in a transmission device used in an identification system using microwaves.

[0002]

2. Description of the Related Art A system has been put to practical use in which a radio wave from a transmitting device is received by a recognition device (communicator) to recognize an article or to check a person entering or leaving a gate. The transmission device used in such a system is formed in a tag (tag form) or card shape, and a reflection type or active type transmission device is used.
The reflection type transmission device is provided with an antenna for radio wave reflection on the transmission device main body, and reflects the radio wave transmitted from the recognition device by the antenna and returns the radio wave to the recognition device (for example, Japanese Patent Publication No. 57-24598). .

On the other hand, an active transmission device is provided with a data generation circuit, a transmission circuit for transmitting data, a reception circuit for receiving radio waves transmitted from the recognition device, and the like. Recognition data can be sent in response to radio waves.

[0004]

The reflection type transmission device has a simple structure and can be made small and inexpensive, but cannot transmit data. For this reason, for example, like a logistics management system implemented by courier service or air cargo service,
It could not be used if advanced recognition was required.

On the other hand, an active transmission device can transmit data, but requires a transmission circuit, a reception circuit, and a power supply for these circuits.

SUMMARY OF THE INVENTION It is an object of the present invention to reduce the size of a transmission device capable of transmitting the above-mentioned problem-related data and to operate it without a power supply.

[0007]

The reflection type transmitting apparatus of the present invention comprises an antenna 4 for reflecting an incident continuous wave radio wave 11.
A rectifier circuit (diode D) for generating an operation power supply from the continuous wave; and an identification code generation circuit 2 for operating with the operation power supply obtained by the rectification circuit to generate an identification code. The circuit is the only diode D
And the only diode D is turned on or off in accordance with the identification code generated by the identification code generation circuit 2 to change the impedance of the antenna 4.

[0008]

[Function] By driving the identification code generation circuit with the operating power supply obtained by rectifying the received wave and changing the impedance of the antenna with the generated identification code, the incident radio wave is modulated and re-emitted as reflected radio wave. Also, miniaturization is possible with electric power. Further, the reflection type transmission device includes only one diode, and this only diode functions to rectify the received wave and obtain the operation power of the identification code generation circuit,
An identification code ID generated by the identification code generation circuit
In this case, the rectifying diode is turned on or off in response to the change of the impedance of the antenna.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 2 shows the principle of a reflection type transmission device as a reference example in relation to the embodiment of the present invention. This transmitting device is configured as an ID tag device. The tag body 1 is formed in a thin attachment shape by, for example, a synthetic resin, and has a dipole antenna 4 printed and wired on a flexible substrate or the like provided on the surface as shown in the plan view of FIG. Further, an identification code generator 2 for forming transmission data and a battery 3 as a power supply for driving the identification code generator 2 are embedded therein.

The identification code generator 2 is composed of a one-chip IC in which an oscillator 5, an address counter 6, a memory 7, and an FET transistor 8 are integrated, and consumes very little power.

The memory 7 is, for example, a writable ROM (PR
OM), in which data sent from the ID tag device is written. That is, for example, when an ID tag device is used in a physical distribution system, data such as the type and receipt number of a package, names of recipients and senders, and destinations are coded (digitized) and written.

The positive and negative electrodes of the battery 3 are directly connected to the terminals 2a and 2b provided on the identification code generator 2, respectively, and the identification code generator 2 is always operating. Therefore, the data generation circuit 9 including the oscillator 5, the address counter 6, and the memory 7 is always operating, and the clock signal ck of a predetermined frequency is constantly derived from the oscillator 5 to the address counter 6.

An address counter 6 designates an address of the memory 7, and data written at the designated address is read. The address counter 6 receives the clock signal c
Since the count is incremented each time k is given and the next address is designated, the data written in the memory 7 is read one after another. The read data is applied to the gate electrode of the FET transistor 8 as a series of identification codes ID composed of digital signals. Therefore, the potential of the gate electrode changes to a high potential and a low potential in accordance with the contents (data) of the identification code ID, so that the transistor 8 performs an on / off operation according to the identification code ID.

The transistor 8 has a source electrode grounded and a drain electrode connected to the terminal 2 c of the identification code generator 2. Therefore, when the transistor 8 is turned on / off, the impedance between the terminals 2b and 2c changes. Feeding points 4a and 4b of the antenna 4 are connected to the terminals 2b and 2c.

As shown in the system block diagram of FIG.
Transmission antenna 12 of communicator 10 which is a recognition device
When receiving the continuous wave transmission wave 11 in the microwave band radiated from the antenna, a voltage is induced in the dipole antenna 4 and
The reception current I flows. Therefore, the radio wave received from the dipole antenna 4, that is, the transmission wave 11 radiated from the communicator 10 is re-radiated. The communicator 10 receives and demodulates the re-radiated radio wave, that is, the reflected wave 14 from the dipole antenna 4 by the receiving antenna 13.

The impedance between the terminals 2b and 2c (between the feeding points 4a and 4b) changes according to the on / off state of the transistor 8. When the transistor 8 is turned on, the impedance between the feeding points 4a and 4b becomes, for example, 50 [Ω], and the dipole antenna 4 matches the transmission wave 11 of 2.45 GHz. When the transistor 8 is turned off, the impedance of the feeding points 4a and 4b becomes, for example, 1
00 [Ω], and the matching of the dipole antenna 4 is lost. The reflection characteristics of the dipole antenna 4 differ between when matching is achieved and when matching is not achieved. Therefore, there is a difference in phase and amplitude between the reflected wave 14 when matching and the reflected wave when not matching. That is, this ID tag device turns on / off the transistor 8 and modulates the phase of the received radio wave (the transmitted wave 11 from the communicator 10) and reflects it to the communicator 10. . Therefore, the communicator 10 can receive data by receiving a combined wave of the reflected wave 14 and the transmission wave 11 and performing phase or amplitude demodulation.

As described above, the matching state of the dipole antenna 4 corresponds to the on / off of the transistor 8 and the on / off of the transistor 8 corresponds to the identification code ID. Detection becomes possible. Therefore, a carrier for transmitting the identification code ID to the communicator 10.
It is not necessary to provide a transmission circuit and a power supply for transmission since it is not necessary to make the ID tag device with the ID tag device. When the transmission wave 11 from the communicator 10 is received, the reflected wave 14 is automatically generated.
There is no need for a receiving circuit and a receiving power supply for transmitting the identification code ID in response to the above.

Therefore, since only the identification code generator 2 consumes power, the power consumption is extremely small, for example, 1 μA. For this reason, a button battery having a small capacity of about 10 mA / h can be operated continuously for about one year.

This ID tag device can be used in various fields by changing data to be written in the memory 7. For example, if data on a person is written, the system can be applied to a management system for entering and leaving the gate. In this case, the tag main body 1 is preferably formed in a card shape.

Note that another antenna, for example, a microstrip antenna may be used instead of the dipole antenna 4.

FIG. 1 is a main part circuit diagram of a reflection type transmission device showing an embodiment of the present invention in which the ID tag device of FIG. 2 is operated without electric power (without batteries). This transmitting device
Be connected to one voltage supply circuit comprising a series circuit of a diode D and a capacitor C ₁ between the feeding point 4a and 4b of the dipole antenna 4, similarly transmitted to the connection point and 2 of the diode D and the capacitor C Terminal 2a of identification code generator 2 having data generation circuit 9 for generating data to be
And are connected. Further it is connected the other terminal of the capacitor C ₁ (the feed point 4b) and a terminal 2b.

The transmission wave 11 from the communicator 10 received by the dipole antenna 4 is multiplied by the square characteristic of the diode D, and the second harmonic of the transmission wave 11 is re-emitted from the ID tag device as a reflected wave 21. You. In this example, a transmitting dipole antenna 20 that resonates with the second harmonic is provided, and the feeding points 20a and 20b of the antenna 20 are connected to the feeding points 4a and 4b of the dipole antenna 4, respectively, so that the second harmonic can be efficiently recovered. Radiating.

On the other hand, the transmitted wave 11 from the communicator 10 received by the dipole antenna 4 is rectified by the diode D, stored in the capacitor C _1. Therefore, a voltage is generated across the capacitor C ₁ as shown by the arrow A,
This voltage is applied via terminals 2a and 2b to an identification code generator 2 having a data generation circuit 9 similar to that shown in FIG.
The voltage generated at the arrow A depends on the electric field strength at the receiving point, but is usually several mV to several V, so that the identification code generator 2 can be operated sufficiently.

In this example, a shift register 22 in which a plurality of flip-flops FF are connected in series as shown in the block diagram of FIG. 5 is used as the data generation circuit 9 in the identification code generator 2, and each flip-flop FF is The data is stored. The shift register 22 is configured as a serial input serial output type, and stores data (consisting of 0 and 1) from a flip-flop FFn provided at the last stage.
Are output one bit at a time, and the terminal 2
c (output terminal). Also, the output from the last-stage flip-flop FFn is used for the first-stage flip-flop FFn.
1 is input again, and data is circulated.

The identification code ID given to the terminal 2c is
It applied to the anode of the diode D through a capacitor C ₂ and the coil L _1. Therefore, the diodes D are connected to the feeding points 20a (4a) and 20b (4
b), the impedance of the transmitting dipole antenna 20 changes according to the identification code ID. Therefore, the state (phase, amplitude, etc.) of the reflected wave 21 re-emitted from the transmitting antenna 20 depends on the identification code I.
Since it changes according to D, the communicator 10 shown in FIG. 4 receives the reflected wave 21 and demodulates it, so that data generated by the data generating circuit 9 can be obtained.

[0026] Note that the coil L ₁ is a high-frequency choke coil, the reception wave 11 is prevented from flowing to the terminal 2c. The high-frequency manner to ground the output lines of the data by connecting the capacitor C ₃ between the ground and the connection point of the capacitor C ₂ and the coil L _1, a received wave 11 are then prevented from flowing to the terminal 2c.

Next, the block diagram of FIG. 6 shows an example of a system in which reflected waves from a plurality of ID tag devices can be distinguished from each other and identified. As described above, since data transmission is performed using reflected waves of radio waves transmitted from the communicator, if there are a plurality of ID tag devices within a responsive range to the communicator, these ID tags are The reflection from the tag device simultaneously enters the communicator, causing interference.

In the example of FIG. 6, a voltage controlled oscillator (VCO)
26, a sawtooth voltage is applied, and the frequency is ωo + △ ωot.
To generate a ramp-shaped FM wave,
Send from. Assuming that the time from when the FM transmission density 28 is received by the ID tag device and the reflected wave 29 returns to the receiving antenna 13 of the communicator 31 is Δτ, the reception frequency at time t is ωo + Δωot (t− Δτ). The reception wave 29 and the transmission wave 28 are supplied to the mixer 27 to obtain an output signal having a frequency △ ωo △ Δτ which is the difference between the two, and the signal is also supplied to the frequency demodulator 30. Depending on the distance between the communicator 31 and the ID tag device, I
Since the time △ τ until the light is reflected back by the D tag device changes, the difference frequency △ ωoｏτ is a frequency corresponding to the distance from the communicator 31 to each ID tag device.
Therefore, even if there are a plurality of ID tag devices, if the distance from the communicator 31 is different, the reflected waves that are simultaneously incident can be separated because the difference frequency △ ωo △ Δτ is different for each reflected wave. , Specific position (△ τ is a predetermined value)
Is obtained from the demodulator 30 by demodulating the reflected wave from the ID tag device. Therefore, the data sent from the ID tag device can be reproduced by, for example, phase demodulating this output.

[0029]

As described above, according to the present invention, the identification code generation circuit is driven by the operating power supply obtained by rectifying the received radio wave, and the impedance of the antenna is changed by the generated identification code to radiate the reflected wave again. Since it is a configuration,
It is power-free (battery-less) and enables miniaturization, which is the greatest requirement as a portable article (such as an identification tag). In particular, since a battery is unnecessary, maintenance for ionization consumption is not required, and a maintenance-free recognition system can be constructed. In addition, the reflection type transmission device includes only one diode, and this single diode functions to rectify the received wave to obtain the operation power of the identification code generation circuit, and the identification code generated by the identification code generation circuit. Since the rectifying diode is turned on or off in accordance with the ID to perform two functions of changing the impedance of the antenna, the circuit configuration is simple, small, and inexpensive.

[Brief description of the drawings]

FIG. 1 is a block diagram of a reflection type transmission device showing an embodiment of the present invention.

FIG. 2 is a block diagram showing the principle of a reflection type transmission device shown before describing an embodiment of the present invention.

FIG. 3 is a plan view of the ID kugu apparatus.

FIG. 4 is a block diagram of a data transmission / reception system.

FIG. 5 is a block diagram of a data generation circuit using a shift register.

FIG. 6 is a block diagram of a transmission / reception system using a plurality of transmission devices.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 ID tag device 2 identification code generator 3 battery 4 dipole antenna 5 oscillator 6 address counter 7 memory 8 FET transistor 9 data generation circuit 10 communicator 11 transmission wave 12 transmission antenna 13 reception antenna 14 reflected wave 20 transmission dipole antenna 21 reflection Wave D Diode C ₁ Capacitor

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-58-87927 (JP, A) JP-A-54-149596 (JP, A) JP-A-62-123381 (JP, A) JP-A 52-87931 120739 (JP, A) JP-A-63-5287 (JP, A) JP-A-62-277580 (JP, A) JP-A-63-29282 (JP, A) (58) Fields investigated (Int. ^6, DB name) G01S 13/74 - 13/84 H04B 1/04 G08B 13/24

Claims (1)

(57) [Claims] An antenna for reflecting an incident continuous wave radio wave, a rectifier circuit for generating an operation power supply from the continuous wave, and an identification for operating with the operation power supply obtained by the rectification circuit to generate an identification code. A code generation circuit, wherein the rectifier circuit includes only one diode, and the only diode conducts or cuts off according to the identification code generated by the identification code generation circuit, thereby changing the impedance of the antenna. A reflection-type transmission device, wherein