JP2004206409A - Contactless ic card - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a contactless IC card capable of monitoring the electric energy of electric power waves received from the outside and lowering power consumption when the received electric energy is small and performing a high-speed processing when the received electric energy is large by switching to an operation mode corresponding to the electric energy. <P>SOLUTION: In a batteryless type contactless IC card (so-called radio card), the electric energy of the electric power waves transmitted from a contactless IC card reader-writer is detected and changeover to the operation mode corresponding to the detected electric energy is performed. For instance, the changeover to a low power consumption mode is performed if the detected electric energy is small and the changeover to a high-speed operation mode is performed if the detected electric energy is large. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a batteryless non-contact type IC card used as a ticket for passing through an automatic ticket gate or as a personal authentication medium in an entrance / exit management device, for example.
[0002]
[Prior art]
Recently, for example, a non-contact type IC card called a wireless card has been used as a ticket for passing through an automatic ticket gate. In this case, when the user passes through the automatic ticket gate, the non-contact IC card possessed by the user is held over the antenna unit of the automatic ticket gate to perform wireless communication to perform the ticket gate processing. .
[0003]
Also, for example, the entrance / exit management device distributes a non-contact type IC card (wireless card) recording personal physical characteristic information and the like to the entrance / exit, and communicates with a card reader / writer installed at the entrance of the room. By performing wireless communication by using, the physical characteristic information is collated and the opening and closing of the entrance door is controlled.
[0004]
The non-contact type IC card called a wireless card is mainly a battery-less type IC card due to elimination of battery replacement work, downsizing, cost reduction, and long life.
Therefore, recent non-contact type IC cards operate by receiving a power wave transmitted from a card reader / writer, generating an operating voltage using the received power wave, and supplying the operating voltage to each unit as an operating power supply. Has become.
[0005]
However, in the conventional non-contact type IC card, the card itself cannot know the magnitude of the received power wave (the magnitude of the received power), and is not affected by the amount of received power. Instead, it operates with a constant current consumption (current consumption is maximized when operations such as CPU, coprocessor, and memory access inside the card are performed simultaneously).
[0006]
Generally, a shunt regulator as a power generation unit that generates a power supply voltage for operating an IC chip having a CPU, a coprocessor, a memory, and the like is mounted inside a batteryless non-contact IC card. Operates so that its output voltage becomes stable and constant. The output voltage of the shunt regulator is constantly monitored by the power supply voltage monitoring unit, and the operation is stopped when the operation of each unit in the card drops to a voltage that cannot be guaranteed. This function operates regardless of the amount of power received by the contactless IC card.
[0007]
[Problems to be solved by the invention]
However, when the non-contact type IC card is receiving weak power (in a state where the card is at the very last operation), when the maximum current consumption operation such as the coprocessor operation or the memory write operation is performed, the power supply voltage drops. , The operation range of the card becomes narrow, and eventually the operation range of the card becomes narrow (the communication range becomes short).
[0008]
Therefore, the present invention can monitor the power amount of the power wave received from the outside, and can reduce power consumption when the received power amount is small by switching to an operation mode according to the power amount. It is another object of the present invention to provide a non-contact type IC card capable of performing high-speed processing when the amount of received power is large.
[0009]
[Means for Solving the Problems]
The non-contact type IC card of the present invention receives a power wave transmitted from an external device, generates an operation power source by using the received power wave, operates, and performs wireless communication with the external device. In a non-contact type IC card for performing predetermined information processing and the like, power detection means for detecting the power amount of the received power wave, and operation mode switching for switching to an operation mode corresponding to the power amount detected by the power detection means Means.
[0010]
Further, the non-contact type IC card of the present invention provides an antenna for performing wireless communication with an external device, and performs predetermined information processing by performing wireless communication with the external device via the antenna. Information processing means for performing, for example, power supply generation means for receiving a power wave transmitted from an external device via the antenna, generating an operating voltage using the received power wave, and supplying the operating voltage to the information processing means as an operation power supply Power detection means for detecting the power amount of the received power wave, and operation mode switching means for switching the operation mode of the information processing means in accordance with the power amount detected by the power detection means. .
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0012]
FIG. 1 schematically shows a configuration of a non-contact type IC card according to an embodiment of the present invention. The non-contact IC card 10 includes a transmission / reception antenna unit 11 for transmitting and receiving data to and from a non-contact IC card reader / writer (not shown), and modulates transmission data and demodulates reception data. Unit 12, a CPU (Central Processing Unit) 13 for performing various data processing and overall control, a coprocessor 14 for encrypting various data, a non-volatile memory 15 such as an EEPROM for storing various data, a transmitting / receiving antenna unit A power supply as power generation means for generating a stabilized DC voltage by rectifying and smoothing a power wave from the non-contact type IC card reader / writer received at 11 by a rectifier circuit and supplying it as an operating voltage to each unit. A generation unit 16, a power detection unit 17 as a power detection unit for detecting a power amount of the received power wave, and And a mode switching section 18 as the operation mode switching means for switching the operation mode corresponding to the detected amount of power by the output unit 17.
[0013]
The other units 12 to 18 except the transmission / reception antenna unit 11 are configured by one (or a plurality of) IC chips, and are embedded in the card body together with the transmission / reception antenna unit 11.
[0014]
FIG. 2 shows a specific configuration example of the transmission / reception antenna unit 11, the power generation unit 16, and the power detection unit 17. The transmission / reception antenna unit 11 includes a transmission / reception antenna 21 and a tuning capacitor (C1) 22 forming an LC resonance circuit therewith. The power generation unit 16 includes a full-wave rectifier 23, a smoothing capacitor (C2) 24, and a shunt regulator (voltage stabilizing circuit) 25. The power detection unit 17 includes a subtractor 26, an AD converter 27, and a register 28.
[0015]
Next, an operation mainly in detecting power transmitted from the non-contact type IC card reader / writer in such a configuration will be described with reference to a flowchart shown in FIG.
An LC resonance circuit is formed by the transmission / reception antenna 21 and the tuning capacitor 22, and is tuned to a frequency at which a transmission carrier frequency from the non-contact type IC card reader / writer can be induced.
[0016]
Now, the power wave transmitted from the non-contact type IC card reader / writer is received by the transmission / reception antenna 21 and induced at both ends thereof as an AC voltage. The induced AC voltage is full-wave rectified by the full-wave rectifier 23 and then smoothed by the smoothing capacitor 24 to become the DC voltage V1. The DC voltage V1 is a voltage that changes according to the strength (power amount) of the power wave received by the transmitting / receiving antenna 21. When the received power wave is strong, the DC voltage V1 increases, and when the received power wave is weak. , The DC voltage V1 drops.
[0017]
The shunt regulator 25 operates to maintain a constant power supply voltage VCC with respect to the DC voltage V1. The voltage at which the card 10 is activated (operated) is set in advance, and when the generated power supply voltage VCC becomes equal to or higher than the set voltage, the card 10 is activated and operable for the first time (step S1). When the generated power supply voltage VCC becomes equal to or lower than the set voltage (voltage at which operation cannot be guaranteed), the operation is stopped.
[0018]
The subtracter 26 operates to perform subtraction (V1-VCC) between the DC voltage V1 and the generated power supply voltage VCC (step S2). The result of the subtraction is defined as V2, and this voltage V2 is converted into a digital signal by the AD converter 27 (step S3). The converted digital signal is a value (detected power amount) that changes depending on the strength (power amount) of the power wave received by the transmission / reception antenna 21, and is stored in the register 28 (step S4).
[0019]
The mode switching unit 18 determines the operation mode by reading out the value (the detected power amount) に stored in the register 28 by a program process (step S5).
That is, the value χ read from the register 28 is compared with a preset first threshold value VL (step S6), and if the condition of [VL ≧ χ] is satisfied, the power saving mode is set to “low power consumption mode”. Switching is performed (step S7). In this low power consumption mode, the operation clock of each unit is switched to a lower speed (for example, 3.39 MHz) than in the normal operation, and the supply of the operation clock to the CPU 13 and the nonvolatile memory 15 is stopped when the coprocessor 14 operates. In short, when the CPU 13 operates, the supply of the operation clock to the coprocessor 14 and the nonvolatile memory 15 is stopped.
[0020]
If the condition of [VL ≧ χ] is not satisfied in step S6, the value χ read from the register 28 is compared with a second threshold VH (VH> VL) set in advance (step S8), and [χ ≦ [VH], the mode is switched to the "normal operation mode" (step S9). In the normal operation mode, the operation clock of each section is switched to the normal operation (for example, 6.78 MHz), and the operations of the CPU 13 and the coprocessor 14 and the access operation to the nonvolatile memory 15 can be performed simultaneously.
[0021]
If the condition of [χ ≦ VH] is not satisfied in step S8, the mode is switched to the “high-speed operation mode” (step S10). In this high-speed operation mode, the operation clock of each unit is switched to a higher speed (for example, 13.56 MHz) than in the normal operation, and each operation of the CPU 13 and the coprocessor 14 and an access operation to the nonvolatile memory 15 can be performed simultaneously. And
Here, the relationship between each mode and the threshold is shown in FIG.
[0022]
As described above, when the power transmitted from the non-contact type IC card reader / writer is weak (when the power amount of the power wave is small), the value χ stored in the register 28 indicates the low power consumption mode, and the firmware By the processing, the operation is performed so that the individual hardware units such as the CPU 13, the coprocessor 14, and the nonvolatile memory 15 are not simultaneously operated. In addition, the operation clock is switched to a “low power consumption mode” in which the operation clock is made slower than usual and power consumption is suppressed.
[0023]
Further, when the power transmitted from the non-contact type IC card reader / writer is strong (when the amount of power of the power wave is large), the value χ stored in the register 28 indicates the high-speed operation mode, and the CPU 13 , Coprocessor 14, non-volatile memory 15, etc., simultaneously. Further, the operation clock is switched to the “high-speed operation mode” in which the operation clock is faster than the normal operation and the internal processing can be sped up.
[0024]
Therefore, the non-contact type IC card 10 can monitor the amount of power transmitted from the non-contact type IC card reader / writer by the card itself, and by switching to an operation mode corresponding to the amount of power, the received power amount can be reduced. When the amount is small, low power consumption can be realized, and when the amount of received power is large, high-speed processing can be performed.
[0025]
【The invention's effect】
As described above in detail, according to the present invention, the power amount of the power wave received from the outside can be monitored, and by switching to an operation mode corresponding to the power amount, low power consumption is achieved when the received power amount is small. It is possible to provide a non-contact IC card capable of performing high-speed processing when the amount of received power is large.
[Brief description of the drawings]
FIG. 1 is a block diagram schematically showing a configuration of a non-contact type IC card according to an embodiment of the present invention.
FIG. 2 is a circuit diagram showing a specific configuration example of a transmission / reception antenna unit, a power generation unit, and a power detection unit.
FIG. 3 is a flowchart illustrating an operation mainly for detecting power transmitted from a non-contact type IC card reader / writer.
FIG. 4 is a diagram showing a relationship between each mode and a threshold.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Non-contact type IC card, 11 ... Transmission / reception antenna part, 12 ... Modulation / demodulation part, 13 ... CPU (information processing means), 14 ... Coprocessor (information processing means), 15 ... Non-volatile memory (information processing means), 16 ... power generation unit (power generation unit), 17 ... power detection unit (power detection unit), 18 ... mode switching unit (operation mode switching unit), 21 ... transmission and reception antenna, 22 ... tuning capacitor, 23 ... full-wave rectifier, 24: smoothing capacitor, 25: shunt regulator (voltage stabilizing circuit), 26: subtractor, 27: AD converter, 28: register.

Claims (7)

A non-contact type that receives a power wave transmitted from an external device, generates an operation power source by using the received power wave, operates, and performs predetermined information processing and the like by performing wireless communication with the external device. In an IC card,
Power detection means for detecting the amount of power of the received power wave,
Operation mode switching means for switching to an operation mode corresponding to the amount of power detected by the power detection means;
A non-contact type IC card, comprising: An antenna for performing wireless communication with an external device;
Information processing means for performing predetermined information processing by performing wireless communication with an external device via the antenna;
Power generation means for receiving a power wave transmitted from an external device via the antenna, generating an operation voltage by the received power wave and supplying the information processing means as an operation power supply,
Power detection means for detecting the amount of power of the received power wave,
An operation mode switching unit that switches an operation mode of the information processing unit according to the amount of power detected by the power detection unit;
A non-contact type IC card, comprising: The non-contact type IC card according to claim 2, wherein the power detection means detects an amount of power of the power wave received via the antenna based on an input / output voltage difference of the power generation means. The operation mode switching unit switches the operation mode of the information processing unit to a low power consumption mode when the amount of power detected by the power detection unit is smaller than a preset threshold, and is detected by the power detection unit. 3. The non-contact type IC card according to claim 2, wherein the operation mode of the information processing means is switched to a high-speed operation mode when the amount of power is larger than a preset threshold value. The information processing means includes a CPU (Central Processor Unit) that performs various data processing and overall control, a coprocessor that performs encryption of various data, and a non-volatile memory such as an EEPROM that stores various data. Become
In the low power consumption mode, the supply of the operation clock to the CPU and the nonvolatile memory is stopped during the operation of the coprocessor, and the supply of the operation clock to the coprocessor and the nonvolatile memory is stopped during the operation of the CPU. The non-contact type IC card according to claim 4, wherein the non-contact type IC card is stopped. 6. The non-contact type IC card according to claim 5, wherein the CPU, the coprocessor, and the non-volatile memory can be simultaneously operated in the high-speed operation mode. The operation mode switching means further switches the operation clock to the CPU, the coprocessor, and the nonvolatile memory at a lower speed than in the normal operation in the low power consumption mode, and further operates in the high speed operation mode. 7. The non-contact IC card according to claim 5, wherein an operation clock for switching to a non-contact type IC card is switched at a higher speed than in a normal operation.

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