JP2004348660A - Non-contact IC card - Google Patents

Abstract

Provided is a non-contact type IC card capable of preventing the destruction of an IC chip due to heat generation even when an excessive magnetic field is applied from an external device.
In a non-contact IC card (so-called wireless card), when a temperature in an IC chip is judged to be a predetermined level or more by a temperature detecting section provided in the IC chip, the antenna section is connected to the antenna section. By controlling the switching transistors 23a and 23b inserted in series between the rectifier circuit 22 and the rectifier circuit 22 to be off, destruction of the IC chip 31 or separation of the connection portion of the antenna unit 21 due to heat is prevented.
[Selection diagram] Fig. 1

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention is used, for example, as a personal authentication medium in an entrance / exit management device, a basic resident register card, a credit card, or the like, receives an electromagnetic wave transmitted from a non-contact type card reader / writer, and operates the operating voltage by the received electromagnetic wave. A battery-less non-contact type that operates by generating and operating and wirelessly communicates with a non-contact type card reader / writer to perform information processing such as writing and reading data to and from a rewritable nonvolatile memory. The present invention relates to a type IC card (so-called wireless card).
[0002]
[Prior art]
Generally, in this type of non-contact type IC card, when an excessive magnetic field (excessive power) is applied from a non-contact type card reader / writer, which is an external device, the temperature in the IC chip which generates heat is detected by a temperature detection circuit. When the temperature is detected and it is determined that the temperature inside the IC chip is equal to or higher than a predetermined level, the operation of the IC chip is stopped. The temperature detection circuit is configured by hardware, and outputs an interrupt signal to the CPU in the IC chip when detecting a temperature abnormality. The CPU receives the interrupt signal and halts (stops) the operation of the IC chip by firmware (for example, see Patent Documents 1 and 2).
[0003]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 2001-143035
[Patent Document 2]
JP-A-2002-109495 [0005]
[Problems to be solved by the invention]
In the conventional non-contact IC card, as described above, when an excessive magnetic field is applied from the non-contact card reader / writer, when the internal temperature of the IC chip is determined to be equal to or higher than a predetermined level by the temperature detection circuit, the IC The operation of the chip has been stopped.
However, in this method, the operation of the IC chip is stopped, but the card itself continues to receive a magnetic field, and excessive power is continuously supplied to the IC chip. There is a possibility that peeling off of the connection portion may occur.
[0006]
Therefore, an object of the present invention is to provide a non-contact type IC card which can prevent the IC chip from being destroyed by heat even when an excessive magnetic field is applied from an external device.
[0007]
[Means for Solving the Problems]
A non-contact IC card according to the present invention includes an antenna unit for performing wireless communication with an external device, and an electromagnetic wave that is electrically connected to the antenna unit and transmitted from the external device via the antenna unit. IC that has a function of performing predetermined information processing and the like by performing a wireless communication with an external device through the antenna unit through operation by generating an operating voltage using the received electromagnetic wave. A chip, a temperature detecting means for detecting the temperature of the IC chip, and a connection for operating when the temperature of the IC chip detected by the temperature detecting means is equal to or higher than a predetermined value, and connecting the antenna unit and the IC chip. Switch means for interrupting the road.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
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 20 includes an antenna unit 21 for transmitting and receiving data to and from a non-contact IC card reader / writer as an external device (not shown), a rectifying circuit 22 for rectifying an electromagnetic wave received by the antenna unit 21, Switching transistors 23a and 23b as switching means connected in series to connection paths 19a and 19b between the antenna unit 21 and the rectifier circuit 22, respectively, are connected to output terminals of the rectifier circuit 22, and are stabilized by smoothing the rectified output. A power generation unit 24 that generates a converted DC voltage and supplies it to each unit as an operating voltage is connected to the connection terminals 19a and 19b and the output terminal of the rectification circuit 22, and modulates transmission data and demodulates reception data. And a central processing unit (CPU) 26 for performing various information processing and overall control A coprocessor 27 for encrypting various data, a non-volatile memory 28 such as an EEPROM as a storage means for storing various data, and ON / OFF control of switching transistors 23a and 23b according to control signals from CPU 26. The control unit 30 is configured.
[0009]
Here, each unit 22 to 30 except the antenna unit 21 is formed of one IC chip 31 and is embedded together with the antenna unit 21 in the card body. A temperature detecting section 29 as a temperature detecting means for detecting the temperature inside the IC chip 31 is provided in the IC chip 31, and an output signal (temperature detection signal) is sent to the CPU 26.
[0010]
The antenna unit 21 includes a transmission / reception antenna 21a and a tuning capacitor 21b that forms an LC resonance circuit with the transmission / reception antenna 21a. The rectifier circuit 22 is configured by a full-wave rectifier circuit in which four diodes D1 to D4 are bridge-connected. The power generation unit 24 includes a smoothing capacitor, a shunt regulator (voltage stabilizing circuit), and the like.
[0011]
In FIG. 1, the switching transistors 23a and 23b are connected in series to the connection paths 19a and 19b between the antenna unit 21 and the rectifier circuit 22, respectively. However, if the switching transistors are connected in series to at least one of the connection paths, Good.
[0012]
In such a configuration, when an excessive magnetic field is applied from a non-contact type IC card reader / writer (not shown), the temperature detecting unit 29 constituted by hardware detects the temperature inside the IC chip 31 at a predetermined level. If it is determined that this is the case, an abnormal interrupt signal is sent to the CPU 26.
[0013]
At this time, the CPU 26 outputs a control signal for turning off the switching transistors 23a and 23b to the control unit 30 composed of hardware, which is controlled by the firmware stored in the memory 28 by the abnormal interrupt routine. When the control signal is input, the control unit 30 operates to turn off the switching transistors 23a and 23b which are normally on.
[0014]
Next, details of the operation will be described with reference to the flowchart shown in FIG.
The antenna unit 21 receives an electromagnetic wave from the non-contact type IC card reader / writer, and is activated when the voltage generated by the power generation unit 24 becomes higher than the operable voltage (step S1). When activated, after the reset operation (step S2), the operation of the normal routine is started (downloading a program from the memory 28 and setting various functions), and waiting for an instruction from the non-contact type IC card reader / writer. Become.
[0015]
Here, the temperature detection unit 29 constantly monitors the temperature of the IC chip 31 and determines whether or not the temperature is a predetermined temperature X (step S3). If the result of this determination is that the temperature of the IC chip 31 is lower than the predetermined temperature X, normal operation is performed (step S4).
[0016]
However, when an excessive magnetic field from the non-contact type IC card reader / writer is received and it is determined that the temperature has exceeded the predetermined temperature X due to a rise in the temperature of the IC chip 31 (step S3), abnormal temperature detection is performed and the temperature detection unit is detected. 29 outputs an interrupt signal notifying an abnormality to the CPU 26 (step S5).
[0017]
Upon receiving the abnormality interrupt signal, the CPU 26 transfers the abnormality interruption routine to the abnormality detection routine by the firmware (step S6), and outputs a control signal for turning off the switching transistors 23a and 23b to the control unit 30. , 23b are turned off (step S7). When the switching transistors 23a and 23b are turned off, the antenna unit 21 and the rectifier circuit 22 are cut off, so that the card itself becomes insufficient in power and is deactivated.
[0018]
Thereafter, the magnetic field (radio wave) from the non-contact type IC card reader / writer starts to be received again, and when the voltage generated by the power generation unit 24 becomes higher than the operable voltage, it is activated again. Here, when the temperature detection works again, the above operation is repeated.
[0019]
As described above, when an excessive magnetic field is applied from the non-contact type IC card reader / writer, when the temperature in the IC chip 31 is determined to be equal to or higher than a predetermined level by the temperature detecting unit 29 provided in the IC chip 31 , The switching transistors 23a and 23b inserted between the antenna unit 21 and the rectifier circuit 22 are controlled to be turned off.
[0020]
Thereby, the energy induced by the antenna unit 21 cannot be transmitted to the IC chip 31 because the connection between the antenna unit 21 and the rectifier circuit 22 is cut off. This can prevent the destruction of the IC chip 31 or separation of the connection portion such as the antenna section 21 due to heat.
[0021]
【The invention's effect】
As described above in detail, according to the present invention, it is possible to provide a non-contact type IC card capable of preventing the destruction of an IC chip due to heat generation even when an excessive magnetic field is applied from an external device.
[Brief description of the drawings]
FIG. 1 is a configuration diagram schematically showing a configuration of a non-contact type IC card according to an embodiment of the present invention.
FIG. 2 is a flowchart illustrating details of an operation.
[Explanation of symbols]
Reference Signs List 20 non-contact type IC card, 21 antenna part, 21a transmission / reception antenna, 21b tuning capacitor, 22 rectifier circuit, 19a, 19b connection path, 23a, 23b switching transistor (switch means), 24 power supply Generation unit, 25 modulation / demodulation unit, 26 CPU, 27 coprocessor, 28 nonvolatile memory (storage means), 29 temperature detection unit (temperature detection means), 30 control unit, 31 IC chip.

Claims (3)

An antenna unit for performing wireless communication with an external device,
The antenna unit is electrically connected to the antenna unit, receives an electromagnetic wave transmitted from an external device through the antenna unit, generates an operating voltage by the received electromagnetic wave, and operates. An IC chip having a function of performing predetermined information processing and the like by performing wireless communication with the device;
Temperature detecting means for detecting the temperature of the IC chip;
A switch unit that operates when a temperature of the IC chip detected by the temperature detecting unit is equal to or higher than a predetermined value and cuts off a connection path connecting the antenna unit and the IC chip;
A non-contact type IC card, comprising: The IC chip is electrically connected to the antenna unit, has a rectifier circuit that rectifies an output of the antenna unit, and a power supply generator that generates an operating voltage from an output of the rectifier circuit.
The switch unit is connected in series to a connection path connecting the antenna unit and the rectifier circuit, and is normally in an on state, and is turned off when the temperature of the IC chip detected by the temperature detection unit becomes equal to or higher than a predetermined value. 2. The non-contact type IC card according to claim 1, comprising a transistor that performs the operation. 2. The non-contact IC card according to claim 1, wherein said temperature detecting means is provided in said IC chip.

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