JPH0219989A - Information card - Google Patents

Abstract

PURPOSE:To irradiate an electromagnetic wave having a specific frequency from an external part and to read the data of an IC memory under a non- contact state by changing the impedance of a built-in antenna by the data of the IC memory. CONSTITUTION:A dipole antenna 14 to resonate to an ultra high frequency radio wave irradiated from the external part is built in the title card, and the characteristic impedance of this dipole antenna 14 is made variable by a variable impedance element 15 connected to the end of the antenna. Further, the variable impedance element 15 is modulated by the data of a memory 12 built in an information card 10. Thus, the data of the information card can be sent to an external device under the non-contact state without supplying transmission power from the side of the card. Further, the power for the transmission becomes an extremely small value, and the size of the card itself can be formed based on a ISO standard.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an information card that stores information in an IC memory and that can be read by an external device.

[Summary of the invention]

The thin information card of the present invention includes an IC memory in the main body that can store data regarding the card owner or the object to which the card is attached, and the impedance of the antenna is modulated by the data in the IC memory. The information card is equipped with circuit means that can change the information, and by irradiating the information card with electromagnetic waves of a specific frequency from the outside, the data in the IC memory can be read out without contact.

[Conventional technology]

In contrast to magnetic cards, which are thin card format with a magnetic stripe area made of a magnetic film on the surface and record data in this magnetic stripe area, in recent years magnetic cards have been developed with built-in IC memory inside the card. IC cards have been developed in which a large amount of information can be written in the IC memory.

IC cards with built-in IC memory can be used as cards for withdrawing money from bank accounts, cards for identifying individuals,
The contents of the item attached to the item.

It is used as a card to specify the destination (hereinafter referred to as an information card), and usually requires at least a data output terminal or a power supply terminal in order to output the data stored in the semiconductor memory. become.

However, providing a plurality of contact terminals on the surface of the card limits the handling of the card in various ways, and there is a risk that the IC memory may be destroyed by static electricity, noise, and the like.

Therefore, a card (Japanese Unexamined Patent Application Publication No. 57-502080) has a card that houses an ultra-small battery inside and transmits and receives information to and from the IC memory without contact using a light-emitting element or a light-receiving element.
JP-A No. 58-212949) and a card in which a wireless communication device is built into the card to transmit and receive data stored in the card (JP-A No. 62-26591) have been proposed.

[Problem that the invention seeks to solve]

Such an IC card allows data to be sent and received between an external device and the IC card without contact, but it is necessary to send light or electromagnetic waves from the card body to the external device. Therefore, there is a problem in that the battery built into the card is rapidly consumed and the battery has to be replaced more frequently.

Furthermore, when using a battery with a large capacity, there is a problem in that the thickness of the IC card is limited by the size of the battery, making it impossible to reduce the thickness of the IC card.

[Means for solving problems]

The present invention has been made in view of these problems.
For example, a dipole antenna that resonates at a specific frequency is built into a card that has an IC memory inside.
The antenna is configured such that the impedance exhibited by the antenna can be varied according to information data stored in the IC memory.

[Effect]

The reflection characteristics of a dipole antenna change in response to changes in the antenna's impedance, so if the antenna is irradiated with electromagnetic waves of a specific frequency and the antenna impedance is modulated by data in the IC memory, the antenna The phase or level of the reflected wave changes, and the data stored in the IC memory can be detected.

〔Example〕

FIG. 1 shows the inside of an information card 10 of the present invention. The inner surface of the card 1 includes an ultra-thin battery 2, an IC chip 3 equipped with an IC memory, and an SHF band frequency (2,45
A dipole antenna 4 that resonates at GH) is built-in.

Dipole antenna 4. IC chip 3 wiring pattern,
The electrode surface of the battery 2 is formed by printing conductive paint on the card sheet surface, and the IC chip 3 is fixed at the same time as this conductive wiring pattern is printed.

Inside the flat type IC chip 3, as will be described later, there is a variable impedance element (FET) that short-circuits the terminal end of the dipole antenna 4, and a memory section in which data specific to this information card is stored. A memory readout circuit, etc. are formed, and these are integrated into one chip.

Further, the dipole antenna 4 is set in a shape that generates a current distribution of, for example, a half wavelength of radio waves irradiated from the outside.

FIG. 2 is a block diagram of an embodiment of reading stored data from the information card IO described above, where IO is a functional block diagram of the information card, 20 is a functional block diagram of the antenna unit, and 30 is a data processing block diagram. A functional block diagram is shown.

The IC chip inside the information card has an oscillator 11 that generates a clock signal. Memory 12 in which data is stored. A control section 13 is provided to form a readout control signal for the memory 12, and the
The value signal (i,o) is fed to a switching circuit 15 consisting of an FET, which opens and closes the ends of the dipole antenna 14, thereby shorting the antenna or bringing it to the characteristic impedance Z of the antenna.

In the functional block diagram 20 of the antenna unit, 2.45
An oscillator 21 that generates the SHF signal of GH1, a high frequency output amplifier 22. A transmitting antenna 23 is provided to broadcast the output of the high-frequency output amplifier 22 as radio waves, and irradiates the dipole antenna 14 of the information card with electromagnetic waves.

For example, when the information card is used as a tag card for an object, the type of object, destination, and other information are stored as data in the memory lz, and the data in this IC memory is stored in the built-in IC memory. It is repeatedly read out by a control signal from a control circuit 13 that operates using a power source 16 (battery) as a driving source.

Then, the variable impedance element 15 changes the terminating resistance of the dipole antenna 14 to 0Ω or ZΩ (75Ω) based on the “1” and “0” information of the read data.

The radiation impedance of the dipole antenna 14 is Zr.
, if the load impedance is Zl, then Z1=Zr
The maximum received power will be obtained when ZI
=O, the received voltage output to the antenna terminal is 0
, the standing wave ratio of the current flowing through the antenna itself increases, and the re-radiated power P' increases.

As a result, the dipole antenna 14 operates as a reflector, and the receiving antenna 24 of the antenna unit
This reflected wave is received.

The reflected radio wave received by the receiving antenna 24 is converted into a low frequency detection signal by the detector 25 and supplied to the amplifier 26 .

The output of the amplifier 26 is a signal obtained by modulating the impedance of the dipole antenna 14 of the information card, that is, an IC
Contains memory data.

In the data processing section, the output signal of the amplifier 26 is digitized by an A/D converter 31, and is taken into a memory (RAM) 32.

The data taken into the memory (RAM) 32 is sent to the control unit (
The information card is decoded by the CPU 33 and the data on the information card is displayed on the display 34.

Further, this data is sent out as a command signal from the control unit 33 to the outside, and forms a signal for confirming the owner of the information card or for transporting the object to which the information card is attached.

In this way, when the information card is within the receiving area of continuous radio waves output from the receiving antenna 23 of the antenna unit, it always sends its stored data to the outside via the dipole antenna 14. However, since the dipole antenna 14 does not require transmission power,
Even when the IC chip 3 is always in operation, the power consumption of the information card can be made extremely small by using, for example, a MOS type IC circuit.

The information card may detect the power received when the feeding end impedance of the dipole antenna 14 is Z using a diode D, and the IC chip 3 may be in an operating state for a certain period of time based on the detected output.

Furthermore, if the information card has a built-in secondary battery,
It is also possible to use the detection signal of diode D as the battery charging voltage.

Further, when a specific signal is supplied from the antenna unit, the contents of the memory 12 may be rewritten, or a pinhole may be made in the cover sheet of the dipole antenna 14. Alternatively, the data in the IC memory may be rewritten.

〔Effect of the invention〕

As explained above, the information card of the present invention has a built-in dipole antenna that can resonate with super high frequency (SHF) radio waves irradiated from the outside, and the characteristic impedance of this dipole antenna is The transmission power is supplied from the card side by configuring the variable impedance element to be modulated by the data in the memory built into the information card. This has the advantage that the data on the information card can be sent to an external device without contact.

Also, since the power for transmission is extremely small,
It becomes fully possible to form the size of the card itself in compliance with ISO standards.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an overview of the information card of the present invention, and FIG.
The figure is a block diagram of an IC chip built into an information card and a block diagram of an external device for detecting information. In the figure, IO is a functional block diagram of the information card, 12 is a memory, 14 is a dipole antenna, 15 is a switch circuit consisting of a variable impedance element, 20 is an antenna unit block diagram, 23 is a transmitting antenna, 24 is a receiving antenna, and 30 is a A data processing block diagram is shown.

Claims (1)

[Claims] An information card with a built-in IC memory includes a dipole antenna that resonates at a specific frequency, a variable impedance element that is connected to the terminal end of the dipole antenna and changes its characteristic impedance, and a variable impedance element that is connected to the IC memory. An information card characterized in that it houses a circuit means for modulating according to stored data.