JP2002259924A - Data carrier system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a data carrier system which surely wakes up to a normal call signal from an interrogator means and does not wake up to an external noise. SOLUTION: This data carrier system is constituted by a responder means and the interrogator means. When the interrogator means approaches the responder means, communication is executed between the responder means and the interrogator means. An identification signal is added on a top of the signal from the interrogator to call the responder. The responder is equipped with a noise countermeasure circuit to wake up when recognizing the identification signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data carrier system (individual object recognition system), and more particularly to a countermeasure against disturbance noise of a transponder (hereinafter, an ID tag) which is one of components of the data carrier system. It is.

[0002]

2. Description of the Related Art In a data carrier system, an interrogator (reader / writer, hereinafter referred to as R / W) uses microwaves,
This system reads out individual data stored in an ID tag at a position distant from the R / W and writes data to the ID tag. Such a data carrier system is widely used for factory automation (FA), logistics, reading prices of railway tickets and supermarkets, and railway security devices.

Here, an outline of a general data carrier system will be described. FIG. 3 is a block diagram showing a configuration of the data carrier system. In this figure, reference numeral 1 denotes an ID tag, which is mounted on an object to be recognized, and includes a modulation / demodulation circuit 2, an antenna 3, an MPU circuit 4, a memory 5, and a built-in battery 6, which are transmitted from the R / W 7. Its own individual information data is stored in the memory 5.

The R / W 7 includes a transmitting / receiving circuit 8, an antenna 9,
It comprises a modulation / demodulation circuit 10 and an MPU circuit 11, is connected to a host computer 12 via a communication line D3, receives a command from the host computer 12, and
It reads and writes data in the memory 5 in the tag 1. The host computer 12 controls the R / W 7 and collects and manages individual information data of a plurality of ID tags.

In the ID tag 1, the modulation / demodulation circuit 2 modulates the signal transmitted from the MPU circuit 4, transmits the modulated signal as a signal wave by the antenna 3, demodulates the signal wave received by the antenna 3, It transmits a received signal. The MPU circuit 4 manages the transmission / reception data of the reception signal from the modulation / demodulation circuit 2 and the transmission signal to the modulation / demodulation circuit 2.

In the R / W 7, the transmission / reception circuit 8 transmits and receives a transmission wave and a reception wave in communication with the ID tag 1 to the antenna 9.
Is transmitted and received by The modulation / demodulation circuit 10 modulates a signal transmitted to the transmission / reception circuit 8 and demodulates a signal received from the transmission / reception circuit 8. MPU circuit 1
1 manages data to be transmitted and received and controls communication with the host computer 12.

Next, the operation of the ID tag 1 and the R / W 7 will be described. First, the host computer 12 transmits an instruction to write or read individual data to the R / W 7 via the communication line D controlled by, for example, the RS-232C standard.
Next, upon receiving a signal from the host computer 12, the R / W 7 converts the instruction data to ASK (Amplitude Shift).
t Keying) The signal is transmitted to the ID tag 1, which is the object to be recognized, via the modulated transmission wave RD10.

When the modulation / demodulation circuit 2 receives the command data from the R / W 7, the MPU circuit 4 of the ID tag 1
It starts up from the sleep mode in which the circuit is not operating, and decodes the instruction data received and demodulated by the modulation / demodulation circuit 2. Next, the MPU circuit 4 reads or writes data stored in the memory 5 in accordance with the decoded read or write command.

Next, the MPU circuit 4 sends an end signal to the modem circuit 2 after the data processing is completed, and the modem circuit 2
The end signal is subjected to FSK (Frequency Shift Keying) modulation and BPSK (Binary Phase Shift Keying) modulation, and transmitted to the R / W 7 by the antenna 3 as the transmission wave TD10. Here, as a medium of data communication for reading and writing the individual information data between the ID tag 1 and the R / W 7, for example, a microwave in the 2.45 GHz band is used.

[0010] Further, as a standard function in the ID tag 1, there is a wake-up circuit.
When the reception signal from W7 is generated, the MPU circuit 4 in the sleep state is supplied with power and wakes up, and has a function of returning to the sleep state by a command from the MPU circuit 4 when the interrupt processing is completed.

[0011]

However, the ID tag 1 does not wake up with a normal reception signal from the R / W 7, but receives a noise radio wave from the outside and the wake-up circuit malfunctions. There is.

The present invention has been made in view of the above problems, and has as its object to provide a data carrier system that wakes up reliably with a normal calling signal from the R / W and does not wake up with external noise. Is what you do.

[0013]

To solve this problem, a feature of the configuration according to the first aspect of the present invention comprises a transponder means and an interrogator means, and the interrogator means comprises the transponder means. In the data carrier system for executing communication with the interrogator means when the interrogator approaches, the identification signal is added to the head of the signal for calling the transponder from the interrogator.

A feature of the configuration according to claim 2 is that the transponder includes a noise countermeasure circuit that wakes up when the identification signal is recognized.

According to a third feature of the present invention, the identification signal is a pulse train signal having a predetermined cycle, and the noise countermeasure circuit detects a second rising of the identification signal within the predetermined cycle. The point is that sometimes it is judged as a normal call.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a data carrier system according to the present invention will be described with reference to the drawings. FIG. 1 is a block diagram illustrating a functional configuration of the present embodiment. Elements having the same functions as those in FIG. 3 are denoted by the same reference numerals.

First, a normal operation state will be described. In this figure, reference numeral 13 denotes a detection circuit composed of a passive element such as a diode.
A reception signal d from W7 is generated. This reception signal d is input to the wake-up level detection circuit 14.

When the ID tag 1 is in the sleep state, only the memory 5, the wake-up level detection circuit 14, the noise countermeasure circuit 15, and the signal hold circuit 16 are supplied with the power supply voltage VCC1 from the battery 6 and are in an active state.

If the received signal d is equal to or higher than the predetermined level, the wake-up level detection circuit 14 operates, and the noise countermeasure circuit 15 operates by its normal output w1. further,
The signal hold circuit 16 is operated by the normal output w2 of the noise countermeasure circuit 15, and V is set by the normal hold output w2.
The CC2 control circuit 17 is activated, the power supply voltage VCC2 is supplied to other circuits including the MPU circuit 4, and the ID tag 1 enters a wake-up state.

In the wake-up state, the detection circuit 1
The MPU executes an interrupt process based on the third received signal d. When this interrupt processing is completed, the end signal w4 is supplied from the MPU circuit 4 to the VCC2 control circuit 17, the supply of the power supply voltage VCC2 is turned off, and the ID tag 1 returns to the sleep state.

Reference numeral 18 denotes a communication control circuit, which passes the received signal d demodulated by the demodulation circuit 2a to the MPU circuit 4 during the interruption process based on the received signal d from the R / W 7, and is passed from the MPU circuit 4. The data is supplied to the antenna 3 via the modulation circuit 2b, and the radio communication with the R / W 7 is controlled.

Next, the noise countermeasure circuit 15 and the signal hold circuit 16, which are characteristic parts of the present invention, will be described.
The noise countermeasure circuit 15 includes a counter circuit 19 for counting the pulse signal w1 from the wake-up level detection circuit 14 and a feedback clear circuit 20 for receiving one of its own count outputs QA. The other count output QB is supplied as an input w2 of the signal hold circuit 16.

The configuration of the feedback clear circuit 20 is as follows.
A charging circuit comprising a resistor 21 and a capacitor 22 for giving a first-order lag characteristic to the rising edge of the count output QA, and when the voltage of this charging circuit reaches a predetermined threshold value, the charging circuit is inverted and the counter circuit is reset via a reset terminal CLR. 19 comprises an inverter 23 for restoring the initial state.

When the counter circuit 19 operates normally, R
The level of the count output QA is changed from "0" (hereinafter "off") to "1" (hereinafter "on") at the rising edge of the identification signal composed of a pulse train of a predetermined period added to the head of the reception signal "d" from / W7. Further, the counter circuit 19 turns on the count output QB from off at the rise of the second pulse of the identification signal.

When the output from the feedback clear circuit 20 which starts operation when the level of the count output QB changes to ON is given to the reset terminal CLR, the count output Q
The levels of A and QB return to the initial state of off. The level change of the count output QB to ON is determined by the signal hold circuit 1
6 and activates the VCC2 control circuit 17 to wake up the ID tag 1.

When the rising edge of the second pulse of the identification signal is not input to the counter circuit 19, the count output QB remains off and the signal hold circuit 16
Does not activate the VCC2 control circuit 17 via the
Keeps sleep.

Further, based on the waveform diagrams of the respective sections shown in FIG. 2, the operation in the case of normal operation and the case of receiving external noise will be compared and described with a common time axis. (A) is a waveform diagram in the case of normal operation, (B) is a waveform diagram in the case of receiving noise earlier than the cutoff frequency of the detection circuit 13,
(C) is a waveform diagram when a noise that is slower than the operation time of the feedback clear circuit 20 is received.

In the case of (A), as is clear from the description of the normal operation, the count output QB is turned on from the off at the rising of the second pulse of the identification signal P, and the processing of the MPU is performed by wakeup. Executes normally. The time τ from when the count output QA turns on to when the count outputs QA and QB turn off can be determined to be an optimum value by a time constant of the resistor 21 and the capacitor 22 of the feedback clear circuit 20.

FIG. 3B is a waveform diagram when a fast noise is received. Generally, the wake-up level detection circuit 14
Predetermined cut-off frequency (100
(About Hz). In general, the fast external noise has a frequency (several megahertz) much higher than the cutoff frequency, and thus the detection circuit itself cannot respond to the fast noise. Therefore, the count output QB is not turned on due to noise, and the count output QB is kept off, so that the ID tag 1 keeps sleep.

FIG. 3C is a waveform diagram when a slow noise is received. If the operation time τ of the feedback clear circuit 20 is set earlier than the predicted period of the slow noise, the lapse of τ is earlier than the time at which the second pulse of noise is generated, so that the count output QB remains off. Since the count output QA is also turned off and returns to the initial state, the ID tag 1 holds the sleep state.

According to the present embodiment, the identification signal consisting of a pulse train of a predetermined period added to the head of the data from the R / W 7 and the noise countermeasure circuit provided on the ID tag 1 side are slow against radio wave noise of a high frequency. A highly reliable ID tag system that does not cause erroneous wake-up even with radio wave noise of a frequency can be realized.

[0032]

As described above, according to the present invention,
It is possible to realize a data carrier system that wakes up reliably with a normal calling signal from the interrogator means and does not wake up with external noise.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a functional configuration of an embodiment of the present invention.

FIG. 2 is a waveform chart of each part for explaining the operation of one embodiment of the present invention.

FIG. 3 is a block diagram illustrating a configuration example of a conventional data carrier system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... ID tag (response means) 2a ... Demodulation circuit 2b ... Modulation circuit 3 ... Antenna 4 ... MPU circuit 5 ... Memory 6 ... Battery 13 ... Detection circuit 14 ... Wakeup level detection circuit 15 ... Noise countermeasures Circuit 16 ... Signal hold circuit 17 ... VCC2 control circuit 18 ... Communication control circuit 19 ... Counter circuit 20 ... Feedback clear circuit

Continued on the front page F term (reference) 5B035 BB09 CA12 CA23 CA31 5B058 CA15 CA23 5K012 AB05 AB12 AC01 AC09 AC11 AD02 BA02 BA07 BA15

Claims (3)

[Claims] 1. A data carrier system comprising: transponder means and interrogator means, wherein said interrogator means communicates with said interrogator means when said interrogator means is close to said transponder means. A data carrier system, wherein an identification signal is added to the head of a signal for calling the transponder. 2. The data carrier system according to claim 1, wherein the transponder includes a noise countermeasure circuit that wakes up when the identification signal is recognized. 3. The identification signal is a pulse train signal having a predetermined period, and the noise countermeasure circuit determines a normal call when detecting a second rising of the identification signal within the predetermined period. The data carrier system according to claim 1, wherein