JP2003288553A - Non-contact ic card reader - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To always correctly reproduce a transmitted data signal of an IC card. <P>SOLUTION: A non-contact IC card reader is equipped with an antenna 13 which receives a signal outputted as a radio wave from a loaded IC card 11 and having the transmitted data signal including a plurality of waveforms superposed on a carrier, a rectifier circuit 22 which rectifies the signal received by the antenna, a detector circuit 23 which detects the envelope of the rectified signal and outputs a detection signal, an A/D converter 31 which converts the detection signal from analog to digital, a waveform memory 34 which stores a signal of the invariably latest one waveform of the detection signal after the A/D conversion, a threshold calculation means 36 which calculates a threshold for binarizing the detection signal from the signal of the invariably latest one waveform to be stored, a D/A converter 37 which converts the calculated threshold from digital to analog, and a comparator 25 which compares the level of the threshold from the D/A converter with the signal level of the detection signal outputted from the detecting circuit and outputs the comparison result as a reception data signal corresponding to the transmitted data signal of the IC card. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-contact IC card reader device for reading data stored in an IC card mounted therein in a non-contact manner.

[0002]

Information (data) stored in an IC card
A non-contact IC card reader device for reading a document in a non-contact manner is configured as shown in FIG. 7, for example. The IC card 1 is embedded with an antenna, a storage element for storing various kinds of digital information, and an IC chip including a control unit and a transmission / reception circuit for reading / writing information from / to the storage element. The control unit of the IC card 1 is a non-contact IC
When a reading instruction of information (data) is received from the card reader device side through the antenna, the data is read from the storage element to generate the transmission data signal a shown in FIG. 8 and sent to the transmission / reception circuit. The transmission / reception circuit amplitude-modulates the high-frequency carrier signal with this transmission data signal a and outputs it as a transmission signal b via the antenna. In addition, in FIG. 8, the pulse pattern included in the transmission data signal a shows the information to be transmitted.

A transmission signal b shown in FIG. 8 which is a radio wave output from the IC card 1 is received by an antenna 2 installed on the side of the non-contact IC card reader and is sent to a detection circuit 3 as a reception signal c. The detection circuit 3 envelope-detects the received signal c that has been input, and outputs the received signal c as a detection signal d to the next amplifier 4
Send to. The amplifier 4 amplifies the input detection signal d and inputs it as a new detection signal e to the (+) terminal of the comparison circuit 5. A DC threshold voltage f set by a threshold setting circuit 6 including two fixed resistors 6a and 6c and one variable resistor 6b is applied to the (-) terminal of the comparison circuit 5. ing. The comparison circuit 5 compares the detection signal e applied to the (+) terminal with the threshold voltage f applied to the (-) terminal and compares the comparison result with the transmission data signal a of the IC card 1. To the outside as a received data signal g corresponding to.

In the manufacturing factory of the non-contact IC card reader device having such a configuration, the variable resistor 6b of the threshold value setting circuit 6 is adjusted before the factory shipment of the non-contact IC card reader device. As shown in (a), the threshold voltage f is adjusted so as to be located at a substantially intermediate position of the sinusoidal signal waveform of the amplified detection signal e. as a result,
The reception data signal g output from the comparison circuit 5 becomes a pulse-like binarized signal that exactly corresponds to the transmission data signal a of the IC card 1.

[0005]

However, the non-contact IC card reader device shown in FIG. 7 still has the following problems to be solved.

That is, for example, at the time of factory shipment, the threshold setting circuit 6 is adjusted so that the threshold voltage f is positioned at a substantially intermediate position of the sinusoidal signal waveform of the amplified detection signal e. Even if it does, the voltage of the amplified detection signal e changes according to the environment in which the non-contact IC card reader device is installed. Particularly, when the temperature of the environment changes, the voltage of the amplified detection signal e tends to change significantly. Furthermore, when the temperature of the environment changes, the amplification factor of the amplifier 4 also changes.

As a result, there is a case where the threshold voltage f is largely deviated from substantially the middle position of the sinusoidal signal waveform of the detected signal e. In FIG. 9B, the amplification factor of the amplifier 4 increases or the threshold voltage f decreases, and the threshold voltage f largely deviates downward from the middle position of the sinusoidal signal waveform of the detection signal e. FIG. In this case, the amplified detection signal e does not fall to the threshold voltage f, so that the reception data signal g cannot correctly reproduce the transmission data signal a in the IC card 1.

In FIG. 9 (c), the amplification factor of the amplifier 4 is reduced or the threshold voltage f is increased, so that the threshold voltage f
FIG. 6 is a diagram showing a case where is greatly deviated upward from the intermediate position of the sinusoidal signal waveform of the detection signal e. In this case, since the amplified detection signal e does not fall to the threshold voltage f, the reception data signal g cannot correctly reproduce the transmission data signal a in the IC card 1.

Further, the amplification factor of the amplifier 4 and the threshold voltage f change due to the time-dependent change of each element constituting the amplifier 4 and the threshold setting circuit 6, which is caused only by the environmental change such as temperature and humidity. In some cases.

Although it is theoretically possible for the administrator of the information processing apparatus incorporating this non-contact IC card reader to frequently adjust the threshold voltage f of the threshold setting circuit 6, Not practical.

The present invention has been made in view of such circumstances, and even if the environment such as temperature and humidity changes or the elements change over time, the transmission data signal in the IC card is always transmitted. Non-contact IC that can be reproduced correctly
It is an object to provide a card reader device.

[0012]

In order to solve the above problems, in the non-contact IC card reader device of the present invention,
An antenna that receives a signal in which a transmission data signal including a plurality of waveforms is superimposed on a carrier wave, which is output from a mounted IC card as a radio wave, a rectifier circuit that rectifies the signal received by the antenna, and a rectifier circuit that outputs the signal A detection circuit that envelope-detects the rectified signal and outputs a detection signal including a waveform corresponding to the waveform of the transmission data signal; an A / D converter that A / D converts the detection signal output from the detection circuit; The detection signal from the latest 1-waveform signal stored in the waveform memory and the waveform memory that always stores the latest 1-waveform signal in the A / D-converted detection signal output from the / D converter
The threshold value calculating means for calculating the threshold value for binarization and the threshold value calculated by the threshold value calculating means are D /
The D / A converter for A conversion and the level of the threshold value sequentially output from the D / A converter and the signal level of the detection signal output from the detection circuit are compared to determine the comparison result of the IC card. And a comparison circuit that outputs a reception data signal corresponding to the transmission data signal.

In the non-contact IC card reader having the above structure, the signal output from the IC card as a radio wave has a signal waveform in which a transmission data signal including a plurality of waveforms is superimposed on a carrier wave. Therefore, the detection signal obtained by rectifying the signal from the IC card received by the antenna of the non-contact IC card reader device side by the rectification circuit and further performing the envelope detection by the detection circuit does not include the signal component of the carrier wave,
A waveform component and a DC component corresponding to each waveform of the transmission data signal of the card are included.

The detection signal containing the waveform component and the DC component is A / D converted by the A / D converter and written in the waveform memory. In this case, the waveform memory stores only the latest signal of one wavelength in the detected signal. That is, the signal stored in the waveform memory is always updated to the latest signal for one wavelength in synchronization with the clock.

Then, for example, in synchronization with the clock, a threshold value for binarizing the detection signal is sequentially calculated from the latest one waveform signal stored in the waveform memory.
Therefore, the sequentially calculated threshold value has a function such as a moving average.

As described above, the threshold value, which is sequentially updated with the passage of time, naturally changes according to this fluctuation when the signal level of the detection signal changes, and therefore crosses the waveform of the detection signal of this threshold value. The position is almost constant. Therefore, even if the temperature of the environment in which the non-contact IC card reader device is installed changes, the relative positional relationship between the threshold value and the waveform does not change.

Therefore, this threshold value is D / A converted,
The reception data signal obtained by comparing the detected signal with the detection signal in the comparison circuit corresponds exactly to the transmission data signal in the IC card. That is, the transmission data signal in the IC card can be accurately reproduced.

Another invention is the contactless IC card reader device of the invention described above, and further controls the pulse width of each pulse waveform included in the received data signal output from the comparison circuit to a constant value. A waveform shaping circuit is added.

In the contactless IC card reader device thus configured, the pulse width of the pulse waveform included in the received data signal output from the comparison circuit is controlled to a constant value, so that this contactless IC card Misreading of data in the information processing device that processes the received data signal output from the reader device can be prevented.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a schematic configuration of a non-contact IC card reader device according to an embodiment of the present invention. The non-contact IC card reader device of this embodiment is
It has not only the function of reading information (data) stored in the IC card, but also the function of writing various information (data) in the IC card.

In FIG. 1, the non-contact IC of this embodiment
The card reader device is a control unit 12 including a computer that controls the operation of the entire non-contact IC card reader device.
And a writing unit 14 for writing various information (data) to the IC card 11 via the antenna 13 and transmitting a read command, and a reading unit for reading various information (data) from the IC card 11 via the antenna 13. And part 15. The antenna 13 is an antenna for both transmission and reception. That is, under the control of the control unit 12, transmission and reception are performed in different time zones.

The IC card 11 is a conventional I card shown in FIG.
It has the same configuration as the C card 1. That is, this I
In the C card 11, an antenna, a storage element for storing various kinds of digital information, and an IC chip including a control unit and a transmission / reception circuit for reading / writing information from / to the storage element are embedded.

The control unit of this IC card 11 is
When a read command of information (data) is received from the non-contact IC card reader side via the antenna 13, the information (data) is read from the storage element and a plurality of pulse waveforms having the reference pulse width To shown in FIG. A transmission data signal a including 30 is created and sent to the transmission / reception circuit. The transmission / reception circuit amplitude-modulates the high-frequency carrier signal with this transmission data signal a and outputs it as a transmission signal b via the antenna.

First, a case where the control unit 12 writes various information (data) into the IC card 11 will be described. The control unit 12 sends the data to be written in the IC card 11 to the encoder 16 of the writing unit 14. Encoder 16
Converts the data to be written into a write data signal having a serial pulse waveform. The write data signal output from the encoder 16 is input to the signal modulator 17. The signal modulator 17 amplitude-modulates the high-frequency carrier signal transmitted from the carrier oscillator 18 with the write data signal and transmits it as a write signal to the next amplifier 19. The write signal amplified by the amplifier 19 has its noise component removed by the filter 20, is resonated at the frequency of the carrier wave by the resonator 21, and is applied to the antenna 13 as a write signal having large power. . As a result, the write signal is emitted from the antenna 13 as a radio wave.

The transmission / reception circuit of the IC card 11 mounted in this non-contact IC card reader device is the IC card 11
When the write signal is received by the antenna embedded therein, the received write signal is demodulated to the original write data signal and sent to the control unit. The control unit writes the data of the write data signal in the storage element.

Next, a case where the control unit 12 reads various information (data) stored in the IC card 11 will be described. The control unit 12 sends a read command of information (data) stored in the storage element to the IC card 11 via the writing unit 14 and the antenna 13. The control unit 12
Simultaneously sends a reading command to the reading unit 15.
Then, as described above, the transmission signal b shown in FIG. 2 is output as a radio wave from the IC card 11.

The antenna 13 on the side of the non-contact IC card reader receives the transmission signal b output as a radio wave and sends it as a reception signal c to the rectifying circuit 22 composed of a diode in the reading section 15. The rectification circuit 22 half-wave rectifies the input reception signal c as shown in FIG. 2 and sends it to the next detection circuit 23 as a rectification signal h. The detection circuit 23 envelope-detects the input rectified signal h and sends it as a detected signal i to the next amplifier 24.

As described above, since the reception signal c is amplitude-modulated by the transmission data signal a including a plurality of pulse waveforms 30 having the reference pulse width To, this reception signal c
When the rectified signal h is detected by envelope detection, the detected signal i has a DC component and a transmission data signal a as shown in FIG.
A plurality of waveforms 29 corresponding to the respective pulse waveforms 30 are included.

The amplifier 24 receives a plurality of input waveforms 29
The detected signal i including is amplified as a new detected signal j,
The voltage is applied to the (+) terminal of the comparison circuit 25 and the threshold value calculation processing unit 26.

For example, the threshold value calculation processing unit 26 composed of a small-sized microprocessor has a threshold value Th for binarizing the detected signal j from the input detected signal j.
Is calculated and applied to the (−) terminal of the comparison circuit 25. The comparison circuit 25 compares the signal level of the detected signal j after amplification applied to the (+) terminal with the level of the threshold Th applied to the (-) terminal, and compares the result. Is output as a binarized reception data signal n including a plurality of continuous pulse waveforms 40 corresponding to the transmission data signal a in the IC card 11.

The binarized received data signal n output from the comparison circuit 25 is input to the next waveform shaping circuit 27. The waveform shaping circuit 27 controls the pulse width T of each pulse waveform 40 of the input reception data signal n to a constant pulse width Ts, and sends it as a new reception data signal o to the next decoder 28. The decoder 28 converts the input serial signal received data signal o into read data and sends the read data to the control unit 12. Therefore, the control unit 12 can read the information (data) stored in the storage element of the IC card 11.

Next, the detailed configuration and detailed operation of the threshold value calculation processing unit 26 composed of a small microprocessor will be described.

FIG. 3 is a block diagram showing a schematic configuration of the threshold value calculation processing unit 26. This threshold value calculation processing unit 2
A detection signal j output from the amplifier 24 is stored in
Based on the control of the A / D converter 31 for D-converting and outputting the digital detection signal k and the timer 32a, the specified time Δt
A data acquisition unit 32 for acquiring each data (sampling data) D of the A / D converted detection signal k at intervals, and a data determination for determining whether or not the acquired data D should be stored in the waveform memory 34. A section 33 and a waveform memory 34 for storing the data D determined to be stored by the data determination section 33 are provided.

The waveform memory 34 stores the TW for one waveform of the plurality of waveforms 29 included in the A / D converted detection signal k.
A total of eight writing areas 34a are formed with area numbers N of 1 to 8 for temporarily storing the respective data D.
That is, each data SD1 to SD8 written in each of the eight write areas 34a in total is each data D when one waveform 29 is divided into eight equal parts. Specifically, the specified time Δt, which is the time interval for capturing each data D of the A / D-converted detection signal k, is adjusted so that each data D of one waveform TW of the waveform 29 is temporarily stored in the waveform memory 34. Remembered.

Further, in the threshold value calculation processing unit 26,
A waveform for constantly updating the data SD1 to SD8 for one waveform stored in the waveform memory 34 to the latest data SD1 to SD8 for one waveform by using the area value (count value) N counted by the area counter 35a. Memory updating unit 35,
Data SD for one waveform stored in the waveform memory 34
1 to SD8 is used to calculate the latest threshold value Th, and the calculated threshold value Th is D / A converted and applied to the (−) terminal of the comparison circuit 25. A / A converter 37 is provided.

FIG. 4 and FIG. 5 are flow charts showing the detailed operation of the threshold value calculation processing unit 26 composed of the above-mentioned small-sized microprocessor.

When the control unit 12 inputs an information (data) read command for the IC card 11, the data acquisition unit 32 is activated to clear the data SD1 to SD8 in the respective write areas 34a of the waveform memory 34. (Step S1) and the external comparison circuit 2 calculated by the threshold value calculation unit 36.
The threshold value Th set at the (-) terminal 5 is cleared (S2). Further, the writing area (count value) N of the area counter 35a is initialized to 1 (S3).

When the above initialization processing is completed, the control unit 1
Confirm that the reading end command is not input from 2 (S
4) Read one piece of data (sampling data) D in the digital detection signal k output from the A / D converter 31 (S5). In S6, the waveform memory updating unit 35 is activated, and the data D read this time is transferred to the waveform memory 3
4 count value of the area counter 35a (writing area) N
Is written in the writing area 34a designated by (SDN = D).

When the data SD1 to SD8 are not written in all the write areas 34a of N = 1 to 8 of the waveform memory 34 (S7), the process proceeds to S11 of FIG. Waiting, and in S12, the area counter 35
The count value (writing area) N of a is updated (N = N +
1). The updated count value (write area) N is the write area 3
When the number of 4a is 8 or less (S13), the process returns to S5, and one piece of data (sampling data) in the digital detection signal k output from the A / D converter 31.
Read D.

Then, in S7, N = of the waveform memory 34
Data SD1 to SD8 in all write areas 34a of 1 to 8
If is written, the threshold value calculation unit 36 is activated to calculate an average value SDm of the eight data SD1 to SD8 of this one waveform TW (S8). Further, using this average value SDm, a threshold Th for binarizing the portion of the detected signal k containing each waveform 29 is calculated using the following equation (S9).

Th = SDm-α where α is a predetermined constant. The threshold value Th calculated in this way is at a substantially intermediate position (level) of each waveform 29 in the detected signal k, as shown in FIG.

The calculated threshold value Th is converted into an analog threshold value Th by the D / A converter 37 and the comparison circuit 25.
It is set to the (-) terminal of (S10).

Then, the process proceeds to S11 of FIG. 5 and waits for the lapse of the specified time Δt described above, and in S12, the count value (writing area) N of the area counter 35a is updated (N = N).
+1).

When the updated count value (write area) N exceeds 8, which is the number of write areas 34a, the process returns to S3 to initialize the write area.

When a reading end command is input from the control unit 12 in S4, the information (data) of the IC card 11 is input.
Has been read, the waveform memory and the threshold value Th are cleared, and this threshold value calculation processing is ended (S1).
4).

In the threshold value calculation processing unit 26 of the non-contact IC card reader device configured as described above, as shown in FIG.
As shown in FIG. 3, each waveform 29 is located at a position corresponding to each pulse waveform 30 included in the transmission data signal a of the IC card 11.
The detection signal j including is A / D-converted by the A / D converter 31 and the data D is read at the specified time Δt as the digital detection signal k, and the latest eight waveforms of one waveform Tw. Are sequentially written to the waveform memory 34.

That is, the oldest data in the waveform memory 34 is updated to the latest data every specified time Δt. Then, the latest threshold value Th is calculated and output for each specified time Δt. As a result, the threshold value Th applied to the (-) terminal of the comparison circuit 25 is updated to the latest threshold value Th every specified time Δt.

The waveform 29 from which the threshold value Th applied to the (−) terminal of the comparison circuit 25 is calculated is the waveform TW before one waveform of the detection signal j applied to the (+) terminal of the comparison circuit 25. Is. This time delay of one waveform TW can be ignored. Therefore, this calculated threshold value Th naturally changes according to this fluctuation when the signal level of the detected signal k changes, so the detected signal k of this threshold value Th
The position across the waveform 29 in (j) is almost constant.

Therefore, even if the temperature of the environment in which this non-contact IC card reader device is installed changes, the relative positional relationship between the threshold value Th and the waveform 29 does not change, so it was obtained by binarization. Each pulse waveform 40 of the digital reception data signal n corresponds exactly to each pulse waveform 30 of the transmission data signal a in the IC card 11. That is, the information (data) stored in the storage element of the IC card 11 can be accurately read by the control unit 12.

In the detection signal j (k), the threshold value for binarizing the self signal (detection signal k) is obtained by the eight data SD1 to SD8 from one waveform TW of the self signal to the immediately preceding. The value Th is created. As shown in FIGS. 2 and 6, there is no threshold Th for the signal of one wavelength immediately after the start of the detection signal j (k). Therefore, there is no binarized reception data signal n for one wavelength immediately after the start of the detection signal j (k). However, since the carrier wave signal is present before the transmission data signal a, the threshold Th can be set before the transmission data signal a.

The waveform shaping circuit 27 is composed of a monostable circuit (one-shot multivibrator). This monostable circuit is output when the signal level of the reception data signal n having a continuous pulse waveform output from the comparison circuit 25 applied to the input terminal falls from the high (H) level to the low (L) level. The terminal outputs a signal that rises to the high (H) level after maintaining the low (L) level for a fixed time Ts determined by the time constant of the resistor and the capacitor. In this way, the waveform shaping circuit 27 controls each pulse width of the reception data signal n output from the comparison circuit 25 to the constant pulse width Ts.

Therefore, since only the received data signal o having the constant pulse width Ts is input to the decoder 28,
The decoder 28 can correctly convert the input received data signal o into digital read data without error.

The present invention is not limited to the above embodiment. In the apparatus of the embodiment, the threshold value Th is set to the eight data S stored in the waveform memory 34.
The average value SDm of D1 to SD8 and a constant α are obtained, and the threshold value Th is subtracted from the maximum value SDmax of the eight data SD1 to SD8 by a constant value β as shown in the following equation. It is also possible to ask by. Th = SDmax-β In this case, the sampling rate can be slowed down.

Further, the threshold value calculation processing unit 26 of the reading unit 15 can be incorporated in the control unit 12 which controls the operation of the entire non-contact IC card reader device.

[0055]

As described above, in the non-contact IC card reader of the present invention of the present invention, the received signal from the IC card is rectified and detected, and the latest one waveform of the detected signal is detected. The signal data is stored in the waveform memory, the threshold value is sequentially calculated from the latest signal data of one waveform stored in the waveform memory, and the detection signal is binarized by the sequentially calculated threshold value. To obtain the received data signal.

Therefore, even if the environment such as temperature and humidity changes or the elements change over time, the transmission data signal in the IC card can always be reproduced correctly.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a non-contact IC card reader device according to an embodiment of the present invention.

FIG. 2 is a time chart showing the overall operation of the non-contact IC card reader device of the embodiment.

FIG. 3 is a detailed block diagram of a threshold value calculation processing unit in the non-contact IC card reader device of the same embodiment.

FIG. 4 is a flowchart showing a detailed operation of a threshold value calculation processing unit in the non-contact IC card reader device of the embodiment.

FIG. 5 is a flowchart showing a detailed operation of a threshold value calculation processing unit in the contactless IC card reader device of the same embodiment.

FIG. 6 is a time chart showing a detailed operation of a threshold value calculation processing unit in the non-contact IC card reader device of the embodiment.

FIG. 7 is a block diagram showing a schematic configuration of a conventional non-contact IC card reader device.

FIG. 8 is a time chart showing the overall operation of the conventional non-contact IC card reader device.

FIG. 9 is a time chart for explaining problems of the conventional non-contact IC card reader device.

[Explanation of symbols]

11 ... IC card 12 ... Control unit 13 ... Antenna 14 ... Writing section 15 ... Reading unit 16 ... Encoder 17 ... Signal modulator 18 ... Carrier generation circuit 19, 24 ... Amplifier 20 ... Filter 21 ... Resonator 22 ... Rectifier circuit 23 ... Detection circuit 25 ... Comparison circuit 26 ... Threshold value calculation processing unit 27 ... Waveform shaping circuit 28 ... Decoder 29 ... Waveform 30, 40 ... Pulse waveform 31 ... A / D converter 34 ... Waveform memory 36 ... Threshold calculation unit 37 ... D / A converter

Claims (2)

[Claims] 1. An antenna (13) for receiving a signal obtained by superimposing a transmission data signal including a plurality of waveforms on a carrier wave, which is output from a mounted IC card (11) as a radio wave, and a signal received by this antenna. Rectifier circuit (2
2), a detection circuit (23) that envelope-detects the rectified signal output from the rectification circuit and outputs a detection signal including a waveform corresponding to the waveform of the transmission data signal, and the detection circuit (23). A / D converter (31) for A / D converting the detection signal, and a waveform memory for always storing the latest one waveform signal in the detection signal after A / D conversion output from the A / D converter (34), threshold value calculating means (36) for calculating a threshold value for binarizing the detected signal from the latest one-waveform signal stored in the waveform memory, and the threshold value. A D / A converter (37) for D / A converting the threshold value calculated by the calculating means, a threshold level output from the D / A converter, and a detection signal output from the detection circuit. The signal level is compared with the signal level of C comparing circuit (25) for outputting as the card received data signal corresponding to the transmission data signal and the non-contact IC card reader equipped with. 2. The contactless IC card reader device according to claim 1, further comprising a waveform shaping circuit (27) for controlling the pulse width of each pulse waveform included in the received data signal output from the comparison circuit to a constant value. .