JP3254764B2 - Transponder for mobile identification device - Google Patents

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 moving object identification device, and more particularly to a transponder activated by an activation signal from an interrogator and storing a carrier wave (continuous wave, ie, CW wave) from the interrogator. The present invention relates to a transponder for a mobile object identification device used for a vehicle identification system, a distribution management system, or the like, which transmits data by modulating and returning the modulated data.

[0002]

2. Description of the Related Art A communication device (interrogator) provided on a fixed side,
A mobile communication system that communicates with a simple communication device (a transponder) provided on a mobile body side called a doug has attracted attention, for example, a transponder attached to a mobile body that has entered a communication area or An interrogator transmits an interrogation signal to a transponder carried by a human, and is used for a moving object identification device or the like that recognizes a moving object or a person in a non-contact manner based on an identification signal returned from the interrogator.

[0003] In such a mobile object identification device, the power supply of the transponder is almost always using a battery because of its simplicity and light weight. One problem is to reduce the power consumption and extend the battery life. I have. In order to solve this problem, a starting signal modulated at a modulation rate sufficiently lower than the transmission rate of the data signal from the interrogator and a non-modulated carrier continuous with the starting signal, that is, a continuous wave, are fixed in period. The transponder, which repeatedly transmits and receives the activation signal, activates the power control means of the transponder itself to supply power to its own signal processing unit, and includes the identification code (ID code) stored in the storage circuit. The present inventors have proposed a method of modulating an unmodulated carrier transmitted from an interrogator with a start response signal (Japanese Patent Application No. 1-78983). According to this transponder for a mobile object identification device, power is supplied to the signal processing unit when the activation signal is received, so that power consumption can be reduced as compared with a case where power is always supplied. A technique for reducing the power consumption of the transponder by operating the necessary circuit portion only at the time of communication as described above is also described in JP-A-61-201177.

[0004]

However, in the above technique, the starting signal receiving circuit of the transponder which receives the starting signal of the low frequency has a sensitivity from a DC component to a signal in the frequency band of the frequency of the starting signal. When the transponder enters the communication area of the interrogator when the transmission of the activation signal is completed and the unmodulated carrier is transmitted, an input that changes stepwise occurs in the activation signal receiving circuit of the transponder. But
Since this signal contains a signal in the frequency band of the DC component, the activation signal circuit of the transponder mistakenly activates the power control means in response to the activation signal from the interrogator, and the transponder transmits the data signal to the data signal processing circuit. Power is supplied and a start response signal is returned. In this case, since the activation signal from the interrogator is transmitted at a constant period, the activation signal transmitted from the interrogator collides with the activation response signal returned from the transponder, and the normal communication cannot be performed. Occurs. Also, if another interrogator enters the communication area of the interrogator while the interrogator is communicating with another interrogator, the transponder that enters later will return data from the transponder during communication. As a result, an unmodulated carrier wave transmitted from the interrogator is received and an activation response signal is returned, and a collision occurs with the data signal of the transponder during communication, so that normal communication cannot be performed.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem. In the present invention, the transponder returns an activation response signal only by the activation signal from the interrogator, and the activation response signal returned from the transponder is transmitted to the interrogator. It is an object of the present invention to provide a transponder for a mobile object identification device which is prevented from colliding with a start signal transmitted from a communication device or a communication signal of another transponder.

[0006]

To achieve the above object, according to the present invention, there is provided a receiving means continuously supplied with power for receiving a signal including a low-speed start signal, and the start signal is obtained from the received signal. A separating unit which is always supplied with power and a starting signal which is provided in the separating unit and separates the starting signal.
Latch that temporarily holds the signal and outputs it as a discrimination signal
And road, with separate activation signal is input to turn on the switch circuit when the activation signal is input, a start signal receiving circuit frequency band is continuous power is supplied low, on of the switching circuit When the power is supplied by and the discrimination signal from the latch circuit is input.
And a transmitting means for returning an activation response signal to the control unit. According to a second aspect of the present invention, there is provided a receiving unit which is always supplied with power for receiving a signal including a low-speed start signal, and a signal including the received low-speed start signal is input.
Turning on the switch circuit when the signal is input,
And activation signal receiving circuit whose frequency bands are supplied at all times power low, with the power being turned on of the switching circuit is supplied, separating means for separating only the activation signal from the signal including the low speed start signal, the separation Provided in the means
The released start signal is temporarily held and output as a discrimination signal.
A latch circuit to be supplied, and power supplied by turning on the switch circuit, and a discrimination signal from the latch circuit.
And a transmitting means for returning an activation response signal when is input .

[0007]

According to the first aspect of the present invention, the receiving means to which power is always supplied is a signal including a low-speed start signal, for example, a start signal,
Receives carrier waves and data signals. Separation means, which is always supplied with power, separates only the start signal from the received signal
Then, the activation signal is temporarily held by the latch circuit . A startup signal receiving circuit that is always supplied with power and has a low frequency band receives the separated startup signal and turns on the switch circuit when the startup signal is input. And
When power is supplied to the transmission means by turning on the switch circuit, the transmission means receives the discrimination signal from the latch circuit.
When the start response signal is returned. That is, when only the activation response signal is separated, the activation response signal is returned by supplying power to the transponder to activate the transponder. According to the second aspect of the present invention, the receiving means to which power is constantly supplied receives a signal including a low-speed start signal. A starting signal receiving circuit having a low frequency band to which power is always supplied receives a signal including the received low-speed starting signal and turns on the switch circuit when the signal is input. When power is supplied to the separation unit by turning on the switch circuit, the separation unit separates only the start signal from the signal including the low-speed start signal , and latches the signal.
The activation signal is temporarily held by the road. Then, when power is supplied to the transmission means by turning on the switch circuit, the transmission means returns an activation response signal when only the activation signal is separated. That is, to start to supply power to the transponder when it is received a signal including an activation signal, further or latch circuit
When these discrimination signals are input, the start response signal is returned. From the viewpoint of reducing the power consumption, the invention of claim 1 having a short power supply time is superior .

[0008]

Embodiments of the present invention will be described below in detail with reference to the drawings. First, a first embodiment of the present invention will be described. In the first embodiment, the present invention is applied to a so-called tag communication system, and an interrogator 10 arranged on a fixed side shown in FIG.
And a transponder 30 attached to a moving body such as an assembly part moving on the production line or a running car shown in FIG.

As shown in FIG. 1, the interrogator 10 includes a signal processing circuit 12 including a microcomputer. The signal processing circuit 12 transmits a data signal (communication request signal) including a start signal and a command shown in FIG. 6, and a clock generation circuit that inputs a predetermined clock to the transmission circuit 14 and changes a signal transmission speed. 16 and is connected to. The clock generation circuit 16 includes the transmission circuit 1
4 is connected. This transmission circuit 14 is a mixer 18
Is connected to the transmission antenna 22 via the. The mixer 18 is connected to a carrier generation circuit 20 for generating a carrier having a predetermined frequency. The mixer 18 mixes a signal input from the transmission circuit 14 and a carrier input from the carrier generation circuit 20, and Modulates the carrier wave input from the carrier wave generation circuit 20 with the signal input from. The modulated wave is transmitted from the transmitting antenna 22 as a radio wave.

The carrier generation circuit 20 receives the carrier from the carrier generation circuit 20 and transmits an unmodulated carrier from the transmission / reception antenna 26. The carrier is also modulated and returned from the transponder 30 shown in FIG. A transmission / reception circuit 24 for extracting a data signal from the received modulated wave is connected. This transmission / reception circuit 24 is connected to the signal processing circuit 12.

As shown in FIG. 2, the transponder 30 includes a receiving antenna 32 for receiving a start signal and a data signal transmitted from the transmitting antenna 22. Receiving antenna 32
Is connected to a detection circuit 34 that detects a modulated wave received by the reception antenna 32 and obtains an activation signal or a data signal. The detection circuit 34 is connected to a switch circuit 40 via a filter means 36 and a start signal reception circuit 38, and to a signal processing circuit 46 including a microcomputer via a data signal reception circuit 44. .

The filter means 36, as shown in FIG.
It is composed of a hand-pass filter 36A that passes a signal in a predetermined frequency region whose center frequency is the frequency of the start signal, and a latch circuit 36B that temporarily holds the output of the hand-pass filter 36A and outputs it to the signal processing circuit 46 as a discrimination signal. Have been. The reset terminal of the latch circuit 36B is connected to the signal processing circuit 46.
A reset signal is input when the power is turned on to start up, and the holding state is released. The output terminal of the band pass filter 36A is connected to the input terminal of the start signal receiving circuit 38.

As shown in FIG. 4, the start signal receiving circuit 38 amplifies a low-speed start signal passed through the band-pass filter 36A, and converts the signal to a logic level connected to the subsequent stage of the amplifier circuit A1. Comparator C for signal conversion
The output terminal of the comparator C1 is connected to the control terminal P3 of the switch circuit 40. Although FIG. 4 illustrates an example in which the output terminal of the amplifier circuit A1 is connected to the control terminal P3 via the comparator C1, the amplifier circuit A1 is directly connected to the control terminal P3 of the switch circuit 40 as shown by a broken line in FIG. May be connected.

The data signal receiving circuit 44 includes an amplifier circuit A2 for amplifying the high-speed data signal detected by the detector circuit 34, and a comparison for signal conversion to a logic level connected to the subsequent stage of the amplifier circuit A2. The comparator C2 is connected to the signal processing circuit 46.

The relationship between the frequencies of the input signals to the amplifier circuits A1 and A2 and the frequency bands and gains of the amplifier circuits A1 and A2 is, as shown in FIG. Although the configuration is such that the gain can be obtained only in a low frequency band that covers the frequency of the start signal, the amplification circuit A2 included in the data signal reception circuit 44
Has a predetermined gain up to a high frequency band covering the frequency of high-speed data. Here, the low speed refers to a case where the activation signal is slower than the transmission speed of the data signal, and the high speed refers to a case where the transmission speed of the data signal is faster than the transmission speed of the activation signal. For example, when the transmission speed of the start signal is several Kb
When the transmission rate of the data signal is less than ps and the transmission rate of the data signal exceeds several Kbps, the start signal is called low speed and the data signal is called high speed, respectively. Further, a low frequency means that a low-speed start signal can be transmitted and received without distortion (for example, several tens KH).
z or lower), and a high frequency band means a frequency band (for example, several tens KHz or higher) in which a high-speed data signal can be transmitted and received without distortion.

A battery 42 is connected to the filter means 36, the start signal receiving circuit 38, and the switch circuit 40, and is always supplied with power.

The signal processing circuit 46 is connected to a storage circuit 48 for storing data such as an identification code and a transmission circuit 50 for transmitting a data signal containing the identification code. The modulated unmodulated carrier is modulated by the data signal from the signal processing circuit 46 and returned via the transmission / reception antenna 52. Since the data signal receiving circuit 44, the signal processing circuit 46, the storage circuit 48, and the transmitting circuit 50 are connected to the battery 42 via the switch circuit 40, power is supplied to these circuits only when the switch circuit 40 is turned on. Is done.

The operation of this embodiment will be described below. Interrogator 1
0, the signal processing circuit 12 sets the output clock of the clock generation circuit 16 to a predetermined low frequency by the control signal,
An activation signal is output to the transmission circuit 14. The start signal is input to the mixer 18 as a pulse start signal shown in FIG. 6 synchronized with the clock from the clock generation circuit 16. The mixer 18 modulates a carrier having a predetermined frequency generated by the carrier generation circuit 20 with a start signal and transmits the modulated signal from the transmission antenna 22 as a radio wave.

The signal processing circuit 12 transmits the modulated wave from the transmitting antenna 22 and simultaneously operates the transmitting antenna 22 by the control signal to continuously transmit and receive the carrier wave generated by the carrier wave generating circuit 20 without modulating the carrier wave. The signal is transmitted from the antenna 26. In this way, the interrogator 1
0 indicates that a modulated wave modulated by a low-frequency start signal and a carrier wave of an unmodulated wave continuous to the modulated wave are repeatedly transmitted at a constant period. In the present embodiment, the carrier of the modulated wave transmitted from the transmitting antenna 22 and the unmodulated carrier transmitted from the transmitting / receiving antenna 26 have the same frequency. However, two carrier generators for generating carriers of different frequencies are used. Use
Carrier waves having different frequencies may be used.

When the transponder 30 attached to the mobile enters the communication area of the interrogator 10, the receiving antenna 32 receives the modulated wave transmitted from the transmitting antenna 22. This modulated wave is detected by the detection circuit 34 and input to the filter means 36 and the data signal reception circuit 44. The filter means 36 separates the start signal from the received signal by passing only the start signal by the band-pass filter 36A.
8 and the latch circuit 36B. by this,
The start signal receiving circuit 38 turns on the switch circuit 40, and the data signal receiving circuit 44, the signal processing circuit 46, the storage circuit 4
8 and the transmission circuit 50. The latch circuit 36B supplies the discrimination signal to the signal processing circuit 46. As a result, the signal processing circuit 46 starts operating, resets the latch circuit 36B in response to the discrimination signal from the latch circuit 36B, reads an identification code (ID code) from the storage circuit 48, and activates the start response signal including the identification code. Is input to the transmission circuit 50. The transmitting circuit 50 includes a transmitting / receiving antenna 5
The modulated signal is transmitted by modulating the unmodulated carrier received in step 2 with the activation response signal.

The interrogator 10 receives the activation response signal by the transmission / reception antenna 26, and takes the activation response signal into the signal processing circuit 12 via the transmission / reception circuit 24. The signal processing circuit 12 confirms the identification code in the activation response signal, outputs a control signal to the clock generation circuit 16 again, and sets the output clock of the clock generation circuit 16 to a predetermined high frequency corresponding to the transmission rate of the data signal, The data signal including the identification code in the received start response signal is output to the transmission circuit 14.
FIG. 6 shows the data signal synchronized with the high frequency clock output.
Is input to the combiner 18 as a pulse-like data signal, and is transmitted by the transmission antenna 22 as a radio wave obtained by modulating a carrier wave from the carrier wave generation circuit 20 with a data signal.

The radio wave transmitted from the transmitting antenna 22 is
The signal received by the receiving antenna 32 of the transponder 30
4, the filter means 36 and the data signal receiving circuit 4
4 is input. Since the data signal does not include the frequency component of the start signal, the data signal does not pass through the band-pass filter 36A, and as a result, no signal is input to the start signal receiving circuit 38 and the latch circuit 36B. Therefore, the start response signal is not transmitted from the transponder 30 when the data signal is received.

The data signal receiving circuit 44 includes a detection circuit 34
Is input to the signal processing circuit 46. If the data signal is pure data, the signal processing circuit 46 stores the data in the storage circuit 48. If the data signal is a read command, the signal processing circuit 46 outputs a predetermined address of the storage circuit 48. More necessary data is read out, the data is output to the transmission circuit 50, and the unmodulated wave received by the transmission / reception antenna 52 is modulated by the data signal from the signal processing circuit 46 and returned to the interrogator 10.

At the end of the communication, the signal processing circuit 12 of the interrogator 10 transmits a stop command modulated at the same high frequency as the data signal via the transmission circuit 14, the mixer 18, and the transmission antenna 22. This stop command is input to the signal processing circuit 46 via the receiving antenna 32, the detection circuit 34, and the data signal receiving circuit, the switch circuit 40 is turned off, and the data signal receiving circuit 44, the signal processing circuit 4
6. The supply of power to the storage circuit 48 and the transmission circuit 50 is stopped. In the above embodiment, all or part of the functions of the transmission circuit 14 and the clock generation circuit 16 may be processed by software of the signal processing circuit 12, and a RAM is used as the storage circuit 48 of the transponder 30. In this case, the power is always supplied from the battery 42 to the RAM. Further, a signal having a frequency different from that of the start signal may be used as the stop signal, and the signal processing circuit 46 may determine whether the stop signal has been received and turn off the switch circuit 40 when the stop signal is received.

Next, a second embodiment of the present invention will be described. In the present embodiment, as shown in FIG. 7, the filter means of the first embodiment includes a data signal receiving circuit 44 and a signal processing circuit 4.
6, the same reference numerals are given to portions corresponding to those in FIG. 2 and the description thereof will be omitted. As shown in FIG. 7, a filter 54 is connected between the data signal receiving circuit 44 and the signal processing circuit 46. As shown in FIG. 8, the filter means 54 includes a band-pass filter 54A and a latch circuit 54B similar to the band-pass filter 36A of the first embodiment.
The latch circuit 54B temporarily holds the output of the bandpass filter 54A and supplies the output to the signal processing circuit 46 as a discrimination signal. When the discrimination signal is input, the signal processing circuit 46 supplies a reset signal to the filter means 54 to release the holding of the latch circuit 54B, and outputs an activation response signal to the transmission circuit 50 in the same manner as described above. . As a result, the activation response signal is returned only when the activation signal is separated by the filter means 54 as described above. In this embodiment, since no filter means is provided between the detection circuit 34 and the activation signal receiving circuit 38, the transponder 30 enters the communication area of the interrogator 10, and the activation signal from the interrogator 10 or When the antenna 32 receives a non-modulated carrier wave or a communication signal with another interrogator, a signal having a frequency within the frequency band of the amplifier circuit A1 is detected by the detection circuit 34, which is indicated by a broken line in FIG. At this time, power is not supplied to the data signal processing section including the filter means 54, and the data signal processing section including the filter means 54 and the signal processing circuit 46 is not started until the switch circuit 40 is turned on via the activation signal receiving circuit 38. The data signal processing unit operates. Therefore, the filter means is not used for the initial start signal from the interrogator 10 or the unmodulated carrier or the communication signal with another transponder, which activates the transponder 30 to supply power to the signal processing unit. 54 does not operate yet and the activation signal is not separated, so that the classification signal is not input to the signal processing circuit 46, and the activation response signal is not returned. In this case, the activation response signal is transmitted from the interrogator 10 and then output to the latch circuit separated by the filter means 54 when the activation response signal is received by the transponder 30 and output to the data processing circuit 46, The signal is returned via the transmission circuit 50 and the transmission / reception antenna 52.

[0026]

According to the present invention as described above, according to the present invention, electrostatic
The power consumption is reduced, and the
The start-up signal receiving circuit of the transponder
Even if the signal has sensitivity up to the frequency band of the wave number , the start response signal is returned when only the start signal is separated by the transponder. Therefore, collision or communication between the start response signal and the start signal is performed. Thus, there is an effect that the communication can be normally performed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an interrogator.

FIG. 2 is a block diagram showing a transponder according to the first embodiment.

FIG. 3 is a block diagram showing the filter means of FIG. 2;

FIG. 4 is a block diagram showing a start signal receiving circuit and a data signal receiving circuit of FIG. 2;

FIG. 5 is a diagram showing a relationship between a frequency band and a gain of the amplifier circuit.

FIG. 6 is a diagram showing waveforms of a start signal and a data signal.

FIG. 7 is a block diagram showing a transponder according to a second embodiment.

FIG. 8 is a block diagram showing the filter means of FIG. 7;

[Explanation of symbols]

 Reference Signs List 10 interrogator 12 signal processing circuit 14 transmission circuit 16 clock generation circuit 18 combiner 20 carrier generation circuit 22 transmission antenna 24 transmission / reception circuit 26 transmission / reception antenna 30 transponder 32 reception antenna 34 detection circuit 36 filter means 38 start-up signal reception circuit 40 switch circuit 42 Battery 44 Data signal receiving circuit 46 Signal processing circuit 48 Storage circuit 50 Transmission circuit 52 Filter means 36A Band pass filter 36B Latch circuit 54 Filter means

──────────────────────────────────────────────────の Continued on the front page (72) Inventor Souichi Ishikawa 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Takehiko 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (56) References JP-A-3-257726 (JP, A) JP-A-63-134978 (JP, A) JP-A-62-26573 (JP, A) JP-A-3-128534 (JP, A) JP-A-4-263385 (JP, A) JP-A-5-203735 (JP, A) JP-A-5-281347 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01S 13 / 00-13/95 G08G 1/017 H04B 7/26

Claims (2)

(57) [Claims] And 1. A receiving means is continuous power supply for receiving a signal including a low speed start signal is supplied, a separating means for power supply at all times supplied to separate only the activation signal from the received signal, said separating means Provided, separate activation signal for temporary
And a latch circuit that outputs the signal as a discrimination signal while holding the switch, and turns on the switch circuit when the separated start signal is input and the start signal is input. A moving body identification comprising: a signal receiving circuit; and a transmitting means for supplying power when the switch circuit is turned on and returning a start-up response signal when a discrimination signal is input from the latch circuit. Transponder for device. 2. A receiving means which receives a signal including a low-speed start signal, which is always supplied with power, a signal including a received low-speed start signal, and a switch circuit when the signal is input. A start signal receiving circuit that has a low frequency band and is always supplied with power, and a separation that supplies power when the switch circuit is turned on and separates only the start signal from a signal including a low-speed start signal. Means , provided in the separating means, for temporarily separating the separated starting signal.
And a latch circuit that outputs the activation response signal when the switching circuit is turned on and power is supplied and a discrimination signal is input from the latch circuit. Means, and a transponder for a mobile object identification device.