JPH0774673A - Radio type data carrier equipment - Google Patents

Abstract

PURPOSE:To provide the equipment with high security in which no code information is read from a transponder by other devices than a regular interrogator. CONSTITUTION:A bit rate changeover means 13 of a transponder 2 switches a transmission speed from the transponder 2 to an interrogator 1 from a specified bit. A clock changeover means 10 of the interrogator 1 switches to other read clock from the specified bit to cope with the changeover of the transmission speed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless data carrier device.

[0002]

2. Description of the Related Art A conventional wireless data carrier device is shown in FIG.
It is configured as shown in. The wireless data carrier device is an interrogator (interrogator, interrogator).
r) 1 and transponder (transponder, Trans Pon)
der) 2. The interrogator 1 has an antenna coil 3a for both transmission and reception, receives the radio wave of the first frequency f1 from the interrogator 1, and receives the second frequency f2 different from the first frequency f1.
The transponder 2 for transmitting is provided with an antenna coil 3b for both transmission and reception.

The signal of the first frequency f1 generated from the oscillator 4 of the interrogator 1 is transmitted from the antenna coil 3a. This signal is received by the antenna coil 3b of the transponder 2 and rectified by the rectifier circuit 5 so as to cover the power required for operating the transponder 2. The signal of the first frequency f1 generated in the antenna coil 3b is divided by the frequency divider 6b to generate a clock signal CK1 of a specific frequency. The code storage unit 7 to which the clock signal CK1 is input reads the prewritten content at a bit rate determined by the clock signal CK1 and outputs it to the modulator 8. The modulator 8 transmits the signal of the second frequency f2, which is modulated with the information read from the code storage unit 7, to the interrogator 1 via the antenna coil 3b.

The demodulator 9 of the interrogator 1 demodulates the signal of the second frequency f2 received by the antenna coil 3a, reads the demodulated signal with the clock signal CK1 ', and outputs it to the subsequent stage.

The clock signal CK1 'is a signal generated by dividing the signal of the first frequency f1 generated inside the interrogator 1 by the frequency divider 6a, and has the same frequency as the specific frequency. It is synchronized with the clock signal CK1.

[0006] Such a wireless data carrier device is
The interrogator 1 is installed on the fixed side, and the transponder 2
Is installed in the moving body, the interrogator 1 can identify the transponder 2 by reading the code information from the transponder 2 without contacting the transponder 2.

The code storage unit 7 has a storage unit as shown in FIG.
Information is written in the format. The beginning of the information
Minutes based on what is stipulated in the World Shared Code
96-bit identification code D1 is written. This
Of the variable length [for example, 1
60 bits] individual information D2 is written. world
In the shared code, the 96-bit identification code D1
Can read at a bit rate of 4.194 Kbis
The frequency division ratio of the frequency dividers 6a and 6b is defined as the first frequency.
Depending on the wave number f1 and the bit rate of 4.194 Kbis
Constant value (1 / N ₁ ) Is set.

[0008]

SUMMARY OF THE INVENTION With such a configuration,
Only by bringing the carrier of the first frequency f1 and the interrogator 1 set to the bit rate of 4.194 Kbis close to the antenna coil 3b, the individual information D2 can be read out, which is the confidentiality of the individual information D2. ,
Also, it is not preferable from the viewpoint of preventing imitation of the transponder 2, and has low security.

The present invention provides a wireless data carrier device which can read the identification code D1 in accordance with the universal code and can read individual information from the transponder 2 only by the regular interrogator 1. To aim.

[0010]

A wireless data carrier device of the present invention comprises an interrogator for transmitting radio waves as a transmission medium and a transponder for transmitting radio waves modulated with its own code information. A wireless data carrier device for receiving and demodulating a transmitted radio wave on the interrogator side to read the code information, wherein the transponder has a bit rate of its own code information that modulates the radio wave from a specified bit during transmission. It is characterized in that bit rate switching means for switching to a bit rate is provided, and the interrogator is provided with clock switching means for switching the reading clock from the specified bit during reception.

[0011]

According to this structure, in the transponder, the bit rate switching means switches the bit rate from the transponder to the interrogator from the specified bit. In the interrogator, the clock switching means switches the read clock from the specified bit.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. It should be noted that components having the same functions as those of the conventional example shown in FIG.

FIG. 1 shows a wireless data carrier device of the present invention. The interrogator 1 is provided with a sequence section 11a and a specific clock detection section 12a as clock switching means 10 for switching the reading clock, and the transponder 2
3 is different from the conventional apparatus shown in FIG. 3 in that a sequence section 11b and a specific clock detection section 12b are provided as a bit rate switching means 13 for switching the bit rate during transmission.

FIG. 2 shows how the bit rate changes between the interrogator 1 and the transponder 2. The transponder 2 receives the signal of the first frequency f1 and the power required for the output of the rectifier circuit 5 is generated. Then, the transponder 2 is powered on, and the frequency divider 6b turns on the antenna coil 3b.
The signal having the first frequency f1 generated in the first frequency division ratio (1
/ N ₁ ) and the output of the clock signal CK1 is started. When the sequence section 11b counts M ₁ clock signals CK1 and detects the elapse of time T1 (= about 5 ms) from power-on, the clock signal CK to the code storage section 7 is detected.
The output of 1 is started. The code storage unit 7 to which the clock signal CK1 is input is determined by the clock signal CK1 4.1
The content is read at a bit rate of 94 Kbis and output to the modulator 8. The modulator 8 transmits the signal of the second frequency f2, which is modulated with the information read from the code storage unit 7, to the interrogator 1 via the antenna coil 3b.

The specific clock detector 12b counts (M ₁ +3072) clock signals CK1 from power-on to detect the completion time of reading the identification code D1.
The frequency division ratio of the frequency divider 6a is switched to the second frequency division ratio (1 / N ₂ ). The first frequency f1 to the second frequency division ratio (1 / N ₂ )
The second clock signal CK2 generated by frequency division is supplied to the sequence unit 11b.

When the sequence section 11b counts M ₂ clock signals CK2 and detects the elapse of time T2 (= about 5 ms), the clock signal CK2 to the code storage section 7 is detected.
Start the output of.

The code accumulator 7 to which the clock signal CK2 is input is 5.592 Kb determined by the clock signal CK2.
The individual information D2 is read at the bit rate of is and output to the modulator 8. The modulator 8 transmits the signal of the second frequency f2, which is modulated with the information read from the code storage unit 7, to the interrogator 1 via the antenna coil 3b.

As described above, in the transponder 2, the bit rate is 4.194K while the contents are read from the code storage unit 7 and transmitted from the antenna coil 3b.
Switched from bis to 5.592 Kbis.

In the interrogator 1, the sequence section 11a
By changing the frequency division ratio of the frequency divider 6a by the specific clock detection unit 12a in the same manner as the frequency divider 6b of the transponder 2, the identification code D1 and the individual information D2 of the transponder 2 transmitted by switching the bit rate. And read the information accurately.

Specifically, in the interrogator 1, the frequency divider 6a divides the frequency of the carrier of the first frequency f1 supplied to the antenna coil 3a by the first frequency division ratio (1 / N ₁ ) and clocks it. The output of the signal CK1 'is started. Sequence part
11a counts M ₁ clock signals CK1 ′ and detects the elapse of time T1 (= about 5 ms) from power-on, detects 3840 clock signals CK2, and detects the completion time of reading the individual information D2. Then, the frequency division ratio of the frequency divider 6a is switched to the first frequency division ratio (1 / N ₁ ). The interrogator 1 receives the individual information D2 based on the clock signal CK2.
Then, when the elapse of the prescribed time T3 is detected, the transmission of the individual information D2 by the clock signal CK1 is restarted.

With the above configuration, the code storage unit 7
The content of the transponder 2 whose bit rate can be switched from 4.194 Kbis to 5.592 Kbis while the content is read from the antenna coil 3b and being transmitted from the antenna coil 3b has a bit rate of 4.194 K as shown in FIG.
When bis is accessed by the fixed interrogator 1, even if the identification code D1 can be read correctly, the individual information D2 cannot be read, and the transponder 2
Can be expected to improve security.

In the above embodiment, the read bit rate of the individual information D2 is set higher than the read bit rate of the identification code D1, but the read bit rate of the individual information D2 is set lower than the read bit rate of the identification code D1. Can also be expected to improve the security of the transponder 2.

In the above-mentioned embodiment, the transmission frequency of the transponder and the transmission frequency of the interrogator are different, but it is also possible to carry out communication at the same frequency.

[0024]

As described above, according to the present invention, in the transponder, the bit rate switching means switches the bit rate from the transponder to the interrogator from the specified bit, and in the interrogator, the clock switching means changes the read clock from the specified bit. To switch
A general interrogator that does not have a function of switching the read clock from the specified bit cannot read other contents of the identification code written in the transponder. Therefore, by dividing the code information of the transponder into public information and non-public information, transmitting the public information during the period up to the specified bit, and transmitting the non-public information from the specified bit, it becomes possible to transmit to the general interrogator. In this case, the secret information can be kept in a secret state in which it cannot be read, and the illegal action such as reading the information from the transponder to imitate the transponder can be prevented.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a wireless data carrier device of the present invention.

FIG. 2 is an explanatory diagram of a clock signal switching section in the transponder and the interrogator of the same embodiment.

FIG. 3 is a configuration diagram of a conventional wireless data carrier device.

FIG. 4 is a format diagram of information written in a transponder.

[Explanation of symbols]

 1 interrogator 2 transponder 3a, 3b antenna coil 6a, 6b frequency divider 8 modulator 9 demodulator 10 clock switching means 11a, 11b sequence section 12a, 12b specific clock detection section 13 bit rate switching means D1 identification code D2 individual information

Claims (1)

[Claims] 1. An interrogator for transmitting a radio wave as a transmission medium and a transponder for transmitting a radio wave modulated by its own code information, wherein the radio wave transmitted from the transponder side is received and demodulated by the interrogator side. A wireless data carrier device for reading information, the transponder is provided with a bit rate switching means for switching the bit rate of its own code information that modulates radio waves from a specified bit to a different bit rate during transmission, and the interrogator has A wireless data carrier device provided with clock switching means for switching a read clock from the specified bit during reception.