JP2996831B2 - 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 in a vehicle identification system, a distribution management system, or the like, which returns data by modulating and returning the 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 (responder) provided on the mobile body side called a tag 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 as a mobile object, and is used for a purpose such as a mobile object identification device that recognizes a mobile object or a human in a non-contact manner by an identification signal returned from the transponder. Have been.

[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 responding by modulating an unmodulated carrier transmitted from an interrogator with an activation 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 only when an activation signal is received, so that power consumption is reduced as compared with a case where power is always supplied to the signal processing unit. be able to. As described above, the technology for reducing the power consumption of the transponder by operating the necessary circuit portion only during communication is as follows.
It is also described in JP-A-61-201177.

Further, the present inventors have further improved the above-mentioned technology, and provided a band-pass filter or a low-pass filter that passes a signal of a predetermined frequency band whose center frequency is the frequency of the start signal at the subsequent stage of the start signal receiving circuit. A technique has been proposed in which a filter is connected so that another signal is not erroneously detected as a start signal (Japanese Patent Application No. 4-300003).

[0005]

However, in the technique proposed by the present inventors, when the start signal is terminated and the CW wave or the data signal wave is being transmitted, the transponder is located within the communication area of the interrogator. When the intruder enters, a transient signal is inputted to the transponder because the step signal is inputted, and the transient response is continuously outputted from the activation signal receiving circuit for a predetermined time. Since this output contains a signal of a low frequency band, the activation signal is received. In some cases, the signal passes through a low-pass filter or a band-pass filter provided at a subsequent stage of the circuit, and the transponder mistakenly recognizes this output as a start signal and returns a start response signal. in this case,
The start signal from the interrogator transmitted at a fixed period may collide with the start response signal of the transponder, or another transponder entering while the interrogator is communicating with the transponder may generate a CW wave or a data signal wave. If detected, a start response signal is returned and a communication collision occurs, so that a problem arises in that normal communication cannot be performed.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and the transponder recognizes the activation signal from the interrogator without erroneous recognition, and returns the activation response signal only by the activation signal from the interrogator. An object of the present invention is to provide a transponder for a mobile object identification device in which an activation response signal returned from a transponder does not collide with an activation signal transmitted from an interrogator or a communication signal of another transponder.

[0007]

In order to achieve the above object, a transponder for a mobile object identification device according to the present invention comprises: a receiving means for receiving a signal including a start signal composed of a pulse train signal of a predetermined frequency; A start signal recognizing means for recognizing the start signal from the control unit, and a transmitting means for returning a start response signal when the start signal is recognized. The recognizing means includes a filter means for passing a signal in a predetermined band including the frequency of the start signal, a timer means for measuring an elapsed time from a time when the receiving means receives the signal, and a timer means for counting a predetermined time by the timer means. Counter means for counting the number of pulses of the signal that has passed through the filter means, and wherein the transmitting means has a plurality of pulses counted by the counter means. Characterized by returning the activated response signal to come.

[0008]

The receiving means of the present invention receives a signal including a start signal, for example, a start signal composed of a pulse train signal of a predetermined frequency, a carrier wave, a data signal, and the like. The activation signal recognizing means includes a filter means, a timer means, and a counter means, and recognizes only the activation signal from the received signal as described below. Then, only when the activation signal is recognized by the activation signal recognition means, the transmitting means returns the activation response signal, for example, by modulating the unmodulated wave (CW wave) from the interrogator with the data signal. The filter means passes a signal in a predetermined band including the frequency of the start signal, and the timer means measures an elapsed time from the time when the receiving means receives the signal. The counter counts the number of pulses of the signal that has passed through the filter before the timer measures the predetermined time. And
The transmitting means returns an activation response signal when the number of pulses counted by the counter means is plural.

Here, if the transponder enters the communication area of the interrogator while the CW wave or the data signal wave is being transmitted, a step-like signal is input to the transponder. It passes through the filter means and is counted by the counter means. However, since the signal is a step signal, the number of pulses counted by the counter means is only one, and the start response signal is not returned from the transmitting means. On the other hand, in the case of the start signal, the number of pulses counted by the counter means is plural, so the start response signal is returned from the transmitting means. Thus, only the activation signal can be recognized from the signal received by the activation signal recognition means.

Here, the time during which the transient response signal causing the false recognition of the start signal is generated is generally long enough to repeat a plurality of pulses of the start signal. It is preferable to set the length to a length of time during which the transient response signal is generated.

[0011]

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 has 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, which are composed of a pulse train signal of a predetermined frequency shown in FIG. 6, and inputs a predetermined clock to the transmission circuit 14 to transmit a signal. It is connected to a clock generation circuit 16 for changing the speed. The clock generation circuit 16 is connected to the transmission circuit 14. This transmitting circuit 14 is connected to a transmitting antenna 22 via a mixer 18. The mixer 18 is connected to a carrier generation circuit 20 for generating a carrier wave of a predetermined frequency. The mixer 18 mixes a signal input from the transmission circuit 14 with 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, and also modulates the signal from the transponder 30 shown in FIG. A transmission / reception circuit 24 for extracting a data signal from the 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 including a switch 40A via a start signal reception circuit 38 and a switch control circuit 40B for controlling ON / OFF of the switch 40A, and controls a microcomputer via a data signal reception circuit 44. Signal processing circuit 46 configured to include
It is connected to the. The activation signal receiving circuit 38 includes:
It is connected to the signal processing circuit 46 via the activation signal recognition means 36.

[0015] As shown in FIG.
The filter means 36A, which is constituted by a low-frequency pass filter or a band-pass filter, which passes a signal in a predetermined frequency band whose cutoff frequency is the frequency of the start-up signal, starts operation by the output of the filter means 36A, and starts a predetermined T [S
ec] timer means 36B for measuring time, and counter means 36C for counting the number of pulses output from the filter means 36A and outputting the result to the signal processing circuit 46 as a start signal reception flag based on the result. The reset terminal of the counter means 36C is connected to the signal processing circuit 46.
When the signal processing circuit 46 recognizes the activation signal by the activation signal reception flag, a reset signal is immediately issued to wait for the input of the next activation signal.
When the power is turned on, the counter means 36C is in a reset state and waits for input of a start signal.

As shown in FIG. 4, the start signal receiving circuit 38
Is composed of an amplifier circuit A1 for amplifying a low-speed start-up signal passed through the detection circuit 34, and a comparator C1 for signal conversion to a logic level connected to the subsequent stage of the amplifier circuit A1. The output terminal of 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 frequency of the input signal 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, 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. Further, a low frequency means that a low-speed start signal can be transmitted and received without distortion (for example, several tens of k).
Hz), and a high frequency band means a frequency band (for example, several tens kHz or more) in which a high-speed data signal can be transmitted and received without distortion.

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

The signal processing circuit 46 is further 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 received unmodulated carrier is modulated with the data signal from the signal processing circuit 46 and returned via the transmitting / receiving 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, these circuits are connected only when the switch 40A of the switch circuit 40 is turned on. Power is supplied.

The operation of the 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 start signal composed of a pulse train 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 as a radio wave from the transmission antenna 22.

The signal processing circuit 12 transmits the modulated wave from the transmitting antenna 22 and simultaneously activates the transmitting / receiving circuit 24 by the control signal to modulate the carrier generated by the carrier generating circuit 20 and subsequently to the transmitting / receiving antenna without modulating the carrier. 26. In this way, the interrogator 10
Transmits a modulated wave modulated by a low-frequency start signal and a non-modulated carrier wave subsequent to the modulated wave 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. Alternatively, carrier waves having different frequencies may be used.

The transponder 30 attached to the moving body is the interrogator 1
When entering the communication area of 0, the modulated wave transmitted from the transmitting antenna 22 of the interrogator 10 is received by the receiving antenna 32 of the transponder 30. This modulated wave is supplied to a detection circuit 34.
, And input to the start signal receiving circuit 38 and the data signal receiving circuit 44. The signal that has passed through the activation signal receiving circuit 38 is transmitted to the activation signal
0, the switch 40A of the switch circuit 40 is turned on, and the data signal receiving circuit 44, the signal processing circuit 46,
Power is supplied to the storage circuit 48 and the transmission circuit 50.

When the switch 40A is turned on, the timer means 36B in the start signal recognition means 36 starts operating,
As shown in FIG. 7, it operates for a predetermined time T [sec], during which the number of pulses passing through the filter circuit 36A is counted by the counter means 36C. As a result, the activation signal reception flag is set only when the count number is plural. The signal processing circuit 46 to which power has been supplied inspects the activation signal reception flag output from the activation signal recognition means 36. If the flag is set, the signal processing circuit 46 reads an identification code (ID code) from the storage circuit 48, and starts the activation signal including the identification code. The response signal 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. If the activation signal reception flag is not set, the process waits until the next activation signal is issued.

The interrogator 10 receives the activation response signal by the transmission / reception antenna 26 and takes in 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 mixer 18 as a pulse-like data signal shown in FIG. 1 and transmitted by the transmission antenna 22 as a radio wave obtained by modulating the carrier wave from the carrier wave generation circuit 20 with the 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 start signal recognition means 36 and the data signal circuit 4
4 is input. This data signal does not include the frequency component of the start signal. However, as shown in FIG. 8, since the data signal wave is inputted in a stepwise manner, the filter means 36A may output a solid line or a broken line depending on the circuit configuration. (One pulse) is essentially output. Even if the transient response is output in this way, the counter means 36C sets the activation signal reception flag only when counting a plurality of pulses. Therefore, the activation signal reception flag is not set when a data signal is received. The activation response signal is not transmitted from 30.

The data signal receiving circuit 44 includes a detecting 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, and the switch of the switch circuit 40 is turned off, so that the data signal receiving circuit 44, the signal processing circuit 46, The supply of power to the circuit 48 and the transmission circuit 50 is stopped. In the above embodiment, the transmission circuit 1
All or a part of the functions of the clock generation circuit 4 and the clock generation circuit 16 may be processed by software of the signal processing circuit 12, and when a RAM is used as the storage circuit 48 of the transponder 30, the battery 42 Is always supplied with power. Further, a signal having a frequency different from that of the start signal is used as the stop signal. The signal processing circuit 46 determines whether or not the stop signal is received.
May be turned off.

Next, a second embodiment of the present invention will be described. In this embodiment, as shown in FIG. 9, the start signal recognition means 36 of the first embodiment is connected between the start signal receiving circuit 38 and the switch circuit 40. The same reference numerals are given to the same parts and the description is omitted. As in the first embodiment, the activation signal recognition means 36 counter means 36C counts the number of pulses which have passed through the filter means 54A while the timer means 36B is operating. Output a signal. The switch circuit 40 turns on the switch 40A in response to the ON signal, and supplies power to the signal processing circuit 46, the storage circuit 48, the data signal receiving circuit 44, and the transmitting circuit 50. The signal processing circuit 46 reads the identification signal from the storage circuit 48, and returns the identification signal as an activation response signal to the interrogator 10 via the transmission means 50 and the transmission / reception antenna 52. Thereafter, the counter 36C of the activation signal recognizing means 36 is reset in preparation for the next activation signal, and the processing ends.

Therefore, the start response signal is returned only when the start signal is separated by the start signal receiving circuit 36.

In the above embodiment, when the counter means counts a plurality of pulses, the counter means outputs a flag. However, the counter means outputs a signal indicating a count value to the signal processing circuit. Alternatively, the signal processing circuit may determine whether the count value is 2 or more.

[0032]

As described above, according to the present invention, since the activation response signal is returned only when the activation signal is recognized by the transponder, the collision between the activation response signal and the activation signal can be prevented. There is an effect that no communication collision occurs and communication can be performed normally.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an interrogator.

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

FIG. 3 is a block diagram illustrating an activation signal recognition unit 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 diagram showing signal waveforms output from each means with respect to a start signal of a start signal recognition unit of FIG. 3;

FIG. 8 is a diagram showing signal waveforms output from each means for a data signal and a readout wave (CW wave) of the activation signal recognition means of FIG. 3;

FIG. 9 is a block diagram illustrating a transponder according to a second embodiment.

[Explanation of symbols]

 Reference Signs List 10 interrogator 12 signal processing circuit 14 transmission circuit 16 clock generation circuit 18 mixer 20 carrier generation circuit 22 transmission antenna 24 transmission / reception circuit 26 transmission / reception antenna 30 transponder 32 reception antenna 34 detection circuit 36 activation signal recognition means 38 activation signal reception circuit 40 switch Circuit 42 Battery 44 Data signal receiving circuit 46 Signal processing circuit 48 Storage circuit 50 Transmitting circuit 52 Transmitting / receiving antenna 36A Filter means 36B Timer means 36C Counter means

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Chisato Endo 41-41, Chuchu-Yokomichi, Nagakute-cho, Aichi-gun, Aichi Prefecture Inside Toyota Central Research Laboratory Co., Ltd. (72) Inventor Souichi Ishikawa 1st Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Takehiko Okuda 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (56) References JP-A-61-133887 (JP, A) JP-A-2-257726 ( JP, A) JP-A-3-249585 (JP, A) JP-A-2-163681 (JP, A) JP-A-2-83484 (JP, A) JP-A-3-175389 (JP, A) 64-18850 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01S 13/74-13/86 H04B 1/59

Claims (1)

(57) [Claims] 1. A receiving means for receiving a signal including a start signal comprising a pulse train signal of a predetermined frequency; a start signal recognizing means for recognizing a start signal from the received signal; and a start response signal when the start signal is recognized. A responding device for a mobile object identification device, comprising: a transmitting device that returns a signal of a predetermined band including a frequency of the activating signal; and a receiving device. Timer means for measuring an elapsed time from when the signal is received, and counter means for counting the number of pulses of the signal that has passed through the filter means until a predetermined time is measured by the timer means. A transmitting unit that returns an activation response signal when a plurality of pulses are counted by the counter unit;