JP3589092B2 - Non-contact IC card reader - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a non-contact IC card reader that reads and writes data from and to a non-contact IC card.
[0002]
[Prior art]
This type of non-contact IC card reader (hereinafter referred to as an IC card reader) is connected to an IC card via an antenna. The IC card reader periodically transmits data to the IC card via an antenna in order to detect the presence or absence of electromagnetic coupling with the IC card. Here, when the IC card approaches the antenna of the IC card reader, the IC card is electromagnetically coupled to the antenna of the IC card reader and receives data from the IC card reader. Upon receiving the data from the IC card reader, the IC card modulates a start bit consisting of a predetermined number of pulses indicating the start of data transmission after a predetermined time and returns the modulated start bit from its own antenna to the IC card reader. By receiving the start bit, the IC card reader recognizes that the IC card is electromagnetically coupled to itself, and thereafter communicates with the IC card to read data stored in the IC card. And writing data to the IC card.
[0003]
[Problems to be solved by the invention]
By the way, the receiving unit of the IC card reader includes an amplifier for amplifying a received signal received via an antenna, and a comparator for inputting the output of the amplifier, comparing the output with a predetermined threshold value, and outputting the comparison result. However, when the distance from the IC card is short or long, there is a problem that the IC card reader cannot accurately receive data from the IC card.
[0004]
That is, when the distance from the IC card is short, the level of the data signal in the received signal transmitted from the IC card and received by the antenna (a received signal in which data is superimposed on a carrier) is as shown in FIG. Therefore, the level of the data signal extracted from the received signal, amplified and input to the comparator also increases as shown in FIG. When the level of the input signal is large, the comparator outputs eight pulses as start bits as shown in FIG. 6C. Since the start bit is originally composed of four pulses, a reception error of the start bit occurs on the card reader side, and thereafter, there is a problem that data cannot be read or written to the IC card.
[0005]
When the distance from the IC card is long, the level of the signal received from the antenna is small as shown in FIG. 7A, and therefore, the signal is extracted from the received signal, amplified, and input to the comparator. The level of the data signal also decreases as shown in FIG. When the level of the input signal is low, the comparator normally outputs the start bits of four pulses as three pulses as shown in FIG. 7C. As a result, a start bit reception error similarly occurs on the card reader side, and thereafter, data cannot be read from or written to the IC card.
The present invention has been made in view of the above-described problems, and has as its object to enable accurate reception of data from an IC card regardless of the distance to the IC card. .
[0006]
[Means for Solving the Problems]
In order to solve such a problem, the present invention compares a receiving unit that receives a signal from an IC card electromagnetically coupled via an antenna with a level of a received signal output from the receiving unit and a threshold value. A non-contact IC card reader device comprising a comparing means for outputting a comparison result as received data, a counting means for counting the number of pulses of the received data output from the comparing means, and a count value of the counting means being set in advance. a determination unit configured to determine whether to match the set value determined, if the discrepancy between the count value and the set value the judgment means judges and threshold adjusting means for adjusting the threshold value of the comparison means, provided transmitting means for transmitting data periodically to the IC card, receiving means receives the predetermined start bit pulse number sent back from the IC card to the transmission data from the transmitting means signals This is output to the comparison means as a signal.
The comparing means compares the threshold value adjusted by the threshold value adjusting means with the level of the received signal in the next cycle output from the receiving means, and outputs the comparison data as the received data.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram of an IC card reader according to the present invention. The IC card reader 1 reads and writes data from and to an IC card 2 that is electromagnetically coupled. The IC card reader 1 includes a CPU 11, a gate array 12, a transmitting unit 13 that transmits data to the IC card 2, a A receiving unit 16 for receiving data from the IC card 2, an antenna unit 15 for electromagnetically coupling to an antenna (not shown) of the IC card 2, and matching for optimal electromagnetic coupling between the IC card 2 and the antenna unit 15. A matching circuit 14 is provided.
[0008]
The CPU 11 of the IC card reader 1 periodically transmits polling data to the IC card in order to detect the presence or absence of electromagnetic coupling with the IC card 2. The transmission data is transmitted to the transmission unit 13 via the gate array 12, is modulated by the transmission unit 13, and is transmitted as a radio signal to the IC card 2 via the matching circuit 14 and the antenna unit 15.
[0009]
Here, when the IC card 2 approaches the antenna section 15 of the IC card reader 1, an antenna (not shown) of the IC card 2 and the antenna section 15 of the card reader 1 are electromagnetically coupled. As a result, transmission data based on a wireless signal transmitted from the antenna unit 15 of the IC card reader 1 is received on the IC card 2 side.
[0010]
When receiving the transmission data from the IC card reader 1, the IC card 2 modulates a start bit consisting of a predetermined number of pulses indicating the start of data transmission after a predetermined time, and transmits a wireless signal from its own antenna to the IC card reader side. I will send it back. The transmission data of the wireless signal from the IC card 2 is received and demodulated by the receiving unit 16 via the antenna unit 15 and the matching circuit 14. Demodulated data demodulated by the receiving unit 16 is sent to the CPU 11 via the gate array 12.
[0011]
The CPU 11 of the IC card reader 1 receives this demodulated data (that is, the start bit from the IC card 2) to recognize that the IC card 2 is electromagnetically coupled to the IC card reader 1. Then, upon recognizing the electromagnetic coupling with the IC card 2, the CPU 11 of the IC card reader 1 performs data communication with the IC card 2 to which the electromagnetic coupling has been performed and is stored in a memory (not shown) in the IC card 2. It reads out existing data and writes data to the memory of the IC card 2.
[0012]
FIG. 2 is a block diagram showing the configuration of the receiving unit 16 of the IC card reader 1. As shown in FIG. 2, the receiving unit 16 receives data such as start bits from a high-frequency modulated signal (a signal in which data is superimposed on a carrier) a from the IC card 2 via the antenna unit 15 and the matching circuit 14. A low-pass filter 21 for extracting a low-frequency signal corresponding to the following, an amplifier 22 for amplifying the low-frequency signal of the low-pass filter 21, and an amplified signal b of the amplifier 22 are input and compared with a threshold level. A comparator 23 that outputs an amplified signal b having a level or higher as a data signal c to the CPU 11 via the gate array 12 and a threshold level change signal d from the gate array 12 receives a threshold level setting signal. e, and a threshold level adjusting unit 24 for setting the threshold level of the comparator 23.
[0013]
That is, when the receiving section 16 of the IC card reader 1 receives a high-frequency modulated signal from the IC card 2 via the antenna section 15 and the matching circuit 14, the low-pass filter 21 of the receiving section 16 outputs the modulated signal a. , A low-frequency signal corresponding to data such as a start bit is extracted and sent to the amplifier 22. The amplifier 22 amplifies this low-frequency signal and outputs it as an input signal b of the comparator 23. When the input signal b is input to the comparator 23, the comparator 23 compares the input signal b with a threshold level set therein, and outputs the input signal b having a threshold level or higher as a data signal c to the CPU 11 via the gate array 12. .
[0014]
When the gate array 12 receives the above-mentioned start bit indicating the start of data communication with the IC card 2 as the data signal c, the gate array 12 counts the number of pulses of the data signal c and determines that the number of the start bits is four. It is determined whether or not the pulse is composed of the above pulses.
Here, the CPU 11 performs data communication with the IC card 2 based on the signal from the gate array 12 which has been determined that the start bit is composed of four pulses and has been normally received. 2 to read data stored in the memory 2 and write data to the memory of the IC card 2.
[0015]
FIG. 3 shows an example in which the start bit from the IC card 2 is normally received. FIG. 3A shows a modulated signal received by the antenna unit 15 and input to the low-pass filter 21 via the matching circuit 14. 3B is a waveform of a signal b amplified by the amplifier 22 and input to the comparator 23, and FIG. 3C is data (start bit) output from the comparator 23 to the gate array 12 side. 3) The waveform of the signal c.
The example of FIG. 3 is a waveform when the antenna section 15 of the IC card reader 1 and the IC card 2 are at an appropriate distance, and the comparator 23 shown in FIG. The four regular pulses as in c) are transmitted to the gate array 12 as start bits. In such a case, the gate array 12 counts the number of pulses, and since the count value is a predetermined four, the threshold level of the comparator 23 is determined to be an appropriate level, and Is not adjusted.
[0016]
(First Embodiment)
Next, a first embodiment in which the antenna unit 15 of the IC card reader 1 is not at an appropriate distance from the IC card 2 will be described.
When the distance between the antenna section 15 of the IC card reader 1 and the IC card 2 is not appropriate and the distance between them is short, the level of the start bit signal in the modulation signal a becomes large as shown in FIG. Therefore, the level of the input signal b which is amplified by the amplifier 22 and input to the comparator 23 also increases as shown in FIG.
In such a case, based on the threshold level when the distance from the IC card 2 is at an appropriate distance as shown in FIG. The start bit signal c is output to the gate array 12 side. Therefore, in this case, a start bit as shown in FIG. 6C is output to the gate array 12 side as eight pulses.
[0017]
When the start bit is received from the IC card 2 side, the gate array 12 similarly counts the number of pulses and determines whether or not the start bit is composed of four predetermined pulses.
In this example, since the gate array 12 counts eight pulses, it is determined that the level of the received signal from the IC card 2 is large, and the threshold level change signal d corresponding to the level of the received signal is determined. Output to the threshold level adjusting unit 24. At this time, the gate array 12 determines that a reception error has occurred.
[0018]
Upon receiving the threshold level change signal d from the gate array 12, the threshold level adjuster 24 outputs a threshold setting signal e included in the change signal d to the comparator 23 so that the comparator 23 operates. Set the threshold level to the new threshold level.
Thereafter, the IC card reader 1 transmits polling data to the IC card in the next cycle, but since the distance from the IC card 2 is the same as that at the time of the previous polling, the IC card 2 The received waveform of the start bit (the received waveform of the current start bit) returned from the above has a large level as shown in FIG. 4A, as in the previous polling, and the amplified waveform of the amplifier 22 is also shown in FIG. Large as in b).
[0019]
However, since the threshold level of the comparator 23 is set higher than that at the time of the previous polling, the comparator 23 compares the waveform of the input start bit with the new threshold level, and compares the waveform of FIG. As shown, it can be output to the gate array 12 side as four regular pulses. As a result, four regular pulse signals are output from the gate array 12 to the CPU 11, so that the CPU 11 can recognize it as a start bit. Therefore, data communication with the IC card 2 is performed thereafter. It reads data from the IC card and writes data to the IC card. When reading data from the IC card 2, the comparator 23 compares the received data, which is the read data, according to a newly set threshold level, and compares the comparison result via the gate array 12. Output to the CPU 11 side.
[0020]
On the other hand, when the distance between the antenna section 15 of the IC card reader 1 and the IC card 2 is long, the level of the start bit reception signal a becomes small as shown in FIG. Also, the level of the amplified signal b decreases as shown in FIG.
In such a case, in the comparator 23, based on the threshold level when the distance from the IC card 2 is at an appropriate distance, the input signal b having the threshold level or more is used as the start bit signal c as the gate array 12 Output to the side. Therefore, in this case, the start bit is output as three pulses to the gate array 12 as shown in FIG. 7C.
[0021]
When the start bit is received from the IC card 2 side, the gate array 12 similarly counts the number of pulses and determines whether or not the start bit is composed of four predetermined pulses.
In this example, since the gate array 12 counts three pulses, it determines that the level of the received signal from the IC card 2 is low, and issues a threshold change signal d according to the level of the received signal. Output to the threshold level adjustment unit 24. At this time, the gate array 12 determines that a reception error has occurred.
[0022]
Upon receiving the threshold change signal d from the gate array 12, the threshold level adjuster 24 outputs a threshold setting signal e included in the change signal d to the comparator 23, and the threshold of the comparator 23. Set the value level to the new threshold level.
Thereafter, the IC card reader 1 transmits polling data to the IC card in the next cycle. However, since the distance from the IC card 2 is as long as the previous polling, the polling data is returned from the IC card 2. The received waveform of the start bit (the received waveform of the present start bit) has a small level as shown in FIG. 5A, as in the previous polling, and the amplified waveform of the amplifier 22 is also shown in FIG. So small.
[0023]
However, since the threshold level of the comparator 23 is set to a level lower than that at the time of the previous polling, the comparator 23 compares the waveform of the input start bit with the new threshold level, and compares the waveform of FIG. As shown, the pulse is output to the gate array 12 as four regular pulses. As a result, the CPU 11 can recognize the data as a normal start bit, and thereafter performs data communication with the IC card 2 to read data from the IC card and write data to the IC card. When reading data, the comparator 23 compares the received data, which is the read data, with the newly set threshold level, and outputs the comparison result to the CPU 11 via the gate array 12.
[0024]
As described above, the gate array 12 counts the number of pulses of the input start bit and determines whether or not the counted value is a predetermined number (four). The threshold level adjusting unit 24 is instructed to increase the threshold level of the threshold 23 and to lower the threshold of the comparator 23 when the counted number of pulses is smaller than a predetermined number. The relationship between the number of start pulse input pulses and the threshold level of the comparator 23 is actually stored as a table in a memory (not shown) built in the gate array 12, and the gate array 12 follows this table. A threshold level corresponding to the counted number of pulses is transmitted to the threshold level adjusting unit 24, and the comparator 23 is set by the threshold level adjusting unit 24.
[0025]
(Second embodiment)
Next, a second embodiment in which the antenna unit 15 of the IC card reader 1 and the IC card 2 are not at an appropriate distance will be described.
When the distance between the antenna unit 15 of the IC card reader 1 and the IC card 2 is not appropriate and the distance between the two is short, the comparator 23 determines that the distance from the IC card 2 as shown in FIG. Based on the threshold level at a short distance, an input signal b at or above the threshold level is output to the gate array 12 as a start bit signal c. Therefore, in this case, a start bit as shown in FIG. 6C is output to the gate array 12 side as eight pulses.
[0026]
When receiving the start bit from the IC card 2, the gate array 12 similarly counts the number of pulses and determines whether or not this start bit is composed of four pulses. Therefore, it is determined that the level of the received signal from the IC card 2 is large, and a threshold level change signal d corresponding to the level of the received signal is output to the threshold level adjusting unit 24. The threshold level adjuster 24 outputs a threshold setting signal e included in the threshold change signal d to the comparator 23 to set the threshold level of the comparator 23 to a new threshold level. .
[0027]
When a data signal following the start bit transmitted from the IC card 2 is input to the comparator 23, the comparator 23 compares the data signal with a new threshold set at a higher level than when the start bit was received. The comparison result is output to the gate array 12 side. Thus, the gate array 12 can input the data signal following the start bit from the IC card 2 as a normal data signal and transmit the data signal to the CPU 11.
As described above, in the gate array 12, when the pulse number of the start bit from the IC card 2 is larger than the normal pulse number, the threshold level of the comparator 23 is adjusted to a high level, and the data signal following the start bit is adjusted. Are compared with a new threshold value, thereby enabling reception as a normal data signal. As a result, when receiving data from the IC card side, data can be received more quickly than in the first embodiment.
[0028]
On the other hand, even when the distance between the antenna unit 15 of the IC card reader 1 and the IC card 2 is long, the comparator 23 similarly performs the operation when the distance from the IC card 2 is an appropriate distance as shown in FIG. Based on the threshold level, an input signal b having the threshold level or higher is output to the gate array 12 as a start bit signal c. Therefore, in this case, a start bit as shown in FIG. 7C is output as three pulses to the gate array 12 side.
[0029]
When receiving the start bit from the IC card 2 side, the gate array 12 similarly counts the number of pulses and determines whether or not the start bit is composed of four pulses. Therefore, it is determined that the level of the received signal from the IC card 2 is low, and a threshold level change signal d corresponding to the level of the received signal is output to the threshold level adjusting unit 24. The threshold level adjuster 24 outputs a threshold setting signal e included in the threshold change signal d to the comparator 23 to set the threshold level of the comparator 23 to a new threshold level. .
[0030]
When the comparator 23 receives a data signal following the start bit transmitted from the IC card 2 side, the comparator 23 compares the data signal with a new threshold set at a lower level than when the start bit was received. The comparison result is output to the gate array 12 side. As a result, the gate array 12 can input a data signal following the start bit from the IC card 2 as a normal data signal and send it to the CPU 11.
As described above, in the gate array 12, when the pulse number of the start bit from the IC card 2 is smaller than the normal pulse number, the threshold level of the comparator 23 is adjusted to a low level, and the data signal following the start bit is adjusted. Are compared with a new threshold value, thereby enabling reception as a normal data signal. As a result, when receiving data from the IC card side, data can be received more quickly than in the first embodiment.
[0031]
In this way, the level of the waveform received from the IC card 2 (the number of pulses of the start bit) is determined, and the detection sensitivity (threshold level) of the received waveform is changed. As a result, even when the distance between the IC card reader 1 and the IC card 2 is short or long, the data from the IC card 2 can always be received with the optimum sensitivity, and the communication performance is improved.
In the present embodiment, the comparing means (comparator 23) is provided in the receiving means (receiving section 16), but the receiving means and the comparing means may be independently provided.
In this embodiment, the gate array 12 is provided, and the gate array 12 is provided with a function of counting the number of pulses of the start bit and adjusting the threshold value of the comparator 23 based on the counted value. It is also possible for the CPU 11 to have functions. Thereby, a gate array can be made unnecessary.
[0032]
【The invention's effect】
As described above, according to the present invention, a receiving unit that receives a signal from an IC card electromagnetically coupled via an antenna is compared with a level of a received signal output from the receiving unit and a threshold value. In a non-contact IC card reader device comprising a comparison means for outputting a result as reception data, the number of pulses of the reception data output from the comparison means is counted, and whether or not the counted value matches a predetermined set value is determined. Is determined, and when it is determined that the count value does not match the set value, the threshold value (sensitivity) of the comparing means is changed. Therefore, even when the distance between the card reader and the IC card is short, In addition, data can be always received from the IC card with an optimum sensitivity even in a distant place, so that data from the IC card can be accurately received.
In addition, since the level of the threshold level of the comparing means is changed according to whether the count value is larger or smaller than the set value, the threshold value of the comparing means can be adjusted with a simple configuration.
When the count value matches a predetermined set value, the threshold value is not adjusted, so that unnecessary adjustment of the threshold value can be prevented.
Also, a transmitting means for periodically transmitting data to the IC card is provided, and the receiving means uses a predetermined number of start bits returned from the IC card for the transmission data from the transmitting means as a received signal as a comparing means. , The threshold value can be adjusted to an optimal threshold value prior to the start of data communication, so that subsequent data communication can be performed accurately.
Also, since the comparing means compares the threshold value adjusted by the threshold value adjusting means with the level of the received signal of the next cycle output from the receiving means, and outputs the comparison data as the received data. , It is possible to perform accurate reception from data of the next cycle.
When the receiving means receives the start bit transmitted from the IC card and the data signal following the start bit, the receiving means outputs the received signal to the comparing means as a received signal. Since the new threshold value adjusted by the threshold value adjusting means is compared with the data signal level based on the comparison result and the comparison result is output as reception data, the transmission data from the IC card can be quickly received. .
[Brief description of the drawings]
FIG. 1 is a block diagram of a non-contact IC card reader device according to the present invention.
FIG. 2 is a block diagram showing a configuration of a receiving unit of the IC card reader.
FIG. 3 is a waveform chart showing a first reproduction example of a reception waveform in a reception unit.
FIG. 4 is a waveform diagram showing a second reproduction example of a reception waveform in a reception unit.
FIG. 5 is a waveform diagram showing a third reproduction example of a reception waveform in a reception unit.
FIG. 6 is a waveform diagram showing a reproduction example of a reception waveform of a conventional IC card reader.
FIG. 7 is a waveform diagram showing another example of reproduction of a reception waveform of a conventional IC card reader.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Non-contact IC card reader apparatus, 2 ... IC card, 11 ... CPU, 12 ... Gate array, 13 ... Transmission part, 14 ... Matching circuit, 15 ... Antenna part, 16 ... Receiving part, 21 ... Low-pass filter, 22 ... Amplifier 23, comparator 24, threshold level adjuster.

Claims (2)

Receiving means for receiving a signal from an IC card electromagnetically coupled via an antenna, and comparing means for comparing a level of a received signal output from the receiving means with a threshold value and outputting a comparison result as received data; In a non-contact IC card reader device provided with
Counting means for counting the number of pulses of the received data output from the comparing means,
Determining means for determining whether or not the count value of the counting means matches a predetermined set value;
When the determination unit determines that the count value does not match the set value, a threshold value adjustment unit that adjusts a threshold value of the comparison unit ,
Transmitting means for periodically transmitting data to the IC card , wherein the receiving means indicates a start of data transmission returned from the IC card in response to transmission data from the transmitting means. A non-contact IC card reader device, which outputs a received signal when a predetermined number of pulses of a start bit are received . Receiving means for receiving a signal from an IC card electromagnetically coupled via an antenna, and comparing means for comparing a level of a received signal output from the receiving means with a threshold value and outputting a comparison result as received data; In a non-contact IC card reader device provided with
Counting means for counting the number of pulses of the received data output from the comparing means,
Determining means for determining whether or not the count value of the counting means matches a predetermined set value;
A threshold adjusting unit that adjusts a threshold of the comparing unit when the determining unit determines that the count value does not match the set value;
The comparing means compares the threshold value adjusted by the threshold value adjusting means with the level of a received signal of the next cycle output from the receiving means, and outputs comparison data as the received data A non-contact IC card reader device.

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