Non-contact IC card reading/writing apparatus

• US 20040134985A1
• Filed: 12/24/2003
• Published: 07/15/2004
• Est. Priority Date: 12/24/2002
• Status: Active Grant

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Tanaka, Masahiko, Yoshinaga, Hiroshi, Hirata, Akihiko, Deguchi, Futoshi
• Granted Patent: US 7,164,344 B2
• Time in Patent Office: Days
• US Class Current: 235/451
• CPC Class Codes: G06K 19/07 with integrated circuit chips
• CPC Class Codes: G06K 7/0008 General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer
• CPC Class Codes: G06K 7/08 by means detecting the change of an electrostatic or magnetic field, e.g. by detecting change of capacitance between electrodes
• CPC Class Codes: H01Q 1/2208 associated with components used in interrogation type services, i.e. in systems for information exchange between an interrogator/reader and a tag/transponder, e.g. in Radio Frequency Identification [RFID] systems methods or arrangements for sensing record carriers, e.g. for reading patterns G06K7/00; record carrier for use with machines and with at least a part designed to carry digital markings G06K19/00
• CPC Class Codes: H01Q 1/2216 used in interrogator/reader equipment
• CPC Class Codes: H01Q 7/00 Loop antennas with a substantially uniform current distribution around the loop and having a directional radiation pattern in a plane perpendicular to the plane of the loop

Abstract

An object of the present invention is to provide a non-contact IC card reading/writing apparatus having a superior reception characteristic.

A non-contact IC card reading/writing apparatus of the present invention is arranged by employing: a loop antenna for supplying both electric power and a transmission signal to a non-contact IC card by way of an electromagnetic induction effect and for acquiring a reception signal from the non-contact IC card by way of a load variation; a resonant circuit unit for resonating the loop antenna at a desirable frequency; a wireless transmitting unit for supplying both electric power and transmission data via the resonant circuit unit to the loop antenna; and a wireless receiving unit for acquiring a reception signal from the loop antenna via the resonant circuit unit; and is arranged in such a manner that data transmitted from the non-contact IC card is demodulated from the reception signal by a demodulating circuit. In the non-contact IC reading/writing apparatus, the resonant circuit unit, the wireless transmitting unit, and the wireless receiving unit are coupled to each other via any one of a directional coupler, a circulator, and an isolator.

Claims

1. A non-contact IC card reading/writing apparatus comprising:

a loop antenna, which supplies both electric power and a transmission signal to a non-contact IC card by way of an electromagnetic induction effect and acquires a reception signal from the non-contact IC card by way of a load variation;

a resonant circuit, which resonates the loop antenna at a desirable frequency;

a wireless transmitter, which supplies both electric power and transmission data via the resonant circuit to the loop antenna; and

a wireless receiver, which acquires a reception signal from the loop antenna via the resonant circuit;

wherein data transmitted from the non-contact IC card is demodulated from the reception signal by a demodulating circuit; and

the resonant circuit, the wireless transmitter, and the wireless receiver are coupled to each other via a directional coupler.

2. A non-contact IC card reading/writing apparatus comprising:

a loop antenna, which supplies both electric power and a transmission signal to a non-contact IC card by way of an electromagnetic induction effect and acquires reception signal from the non-contact IC card by way of a load variation;

a resonant circuit, which resonates the loop antenna at a desirable frequency;

a wireless transmitter, which supplies both electric power and transmission data via said resonant circuit to the loop antenna; and

a wireless receiver, which acquires a reception signal from the loop antenna via the resonant circuit unit;

wherein data transmitted from the non-contact IC card is demodulated from the reception signal by a demodulating circuit; and

the resonant circuit, the wireless transmitter, and said wireless receiving unit are coupled to each other via a circulator.

3. A non-contact IC card reading/writing apparatus comprising:

a loop antenna, which supplies both electric power and a transmission signal to a non-contact IC card by way of an electromagnetic induction effect and acquires a reception signal from the non-contact IC card by way of a load variation;

a resonant circuit, which resonates the loop antenna at a desirable frequency;

a wireless transmitter, which supplies both electric power and transmission data via the resonant circuit to the loop antenna; and

a wireless receiver, which acquires a reception signal from the loop antenna via the resonant circuit unit;

wherein data transmitted from the non-contact IC card is demodulated from the reception signal by a demodulating circuit;

the resonant circuit, the wireless transmitter, and the wireless receiver are coupled to each other via an isolator.

4. A non-contact IC card reading/writing apparatus comprising:

a loop antenna, which supplies both electric power and a transmission signal to a non-contact IC card by way of an electromagnetic induction effect and acquires a reception signal from the non-contact IC card by way of a load variation;

a first resonant circuit, resonates the loop antenna at a first desirable frequency;

a wireless transmitter, which supplies both electric power and transmission data via the first resonant circuit to the loop antenna; and

a wireless receiver, acquires a reception signal from the loop antenna via a second resonant circuit which is connected to the loop antenna by way of a coupling capacitor and is resonated at a second desirable frequency;

wherein data transmitted from the non-contact IC card is demodulated from the reception signal by a demodulating circuit.

5. The non-contact IC card reading/writing apparatus as claimed in claim 4 wherein:

a resonant frequency of the first resonant circuit is set to a frequency of a carrier wave used to transfer both the electric power and the transmission signal; and

a resonant frequency of the second resonant circuit is set to a frequency of a modulated subcarrier which is produced based upon a load variation occurred on the side of the non-contact IC card.

6. The non-contact IC card reading/writing apparatus as claimed in any one of claim 4 and claim 5 wherein:

a second coil is provided in the vicinity of a first coil which constitutes the second resonant circuit and is coupled to the first coil by way of a mutual induction effect;

one terminal of the first coil is connected to a first ground;

one terminal of the second coil is connected to a second ground; and

the ground of both the wireless transmitter and an antenna circuit is separated from the ground of the wireless receiving unit.

7. The non-contact IC card reading/writing apparatus as claimed in any one of claim 4 to claim 6 wherein:

both a turn number “

n1”

of the first coil which constitutes the second resonant circuit and a turn number “

n2”

of the second coil which is coupled to the first coil by way of the mutual induction effect are selected in such a manner that said turn number “

n1”

is matched to an output impedance “

Z1”

of the second resonant circuit, and the turn number “

n2”

is matched to an input impedance of the wireless receiver; and

both the first coil and the second coil own an impedance converting function.

8. The non-contact IC card reading/writing apparatus as claimed in any one of claim 4 to claim 7 wherein:

both a first capacitor “

C1” and

a second capacitor “

C2”

are series-connected between one terminal and the other terminal of the second coil;

an output signal is derived from a joint point between the first capacitor C1 and the second capacitor C2; and

both the first capacitor C1 and the second capacitor C2 own an impedance converting function.

9. The non-contact IC card reading/writing apparatus as claimed in any one of claim 4 to claim 7 wherein:

the resonant frequency of the second resonant circuit is set to a frequency of a lower-sided modulated subcarrier within both side bands which are formed based upon a load variation occurred on the side of the non-contact IC card.

10. The non-contact IC card reading/writing apparatus as claimed in any one of claim 4 to claim 7 and claim 8 wherein:

the resonant frequency of the second resonant circuit is set to a frequency of an upper-sided modulated subcarrier within both side bands which are formed based upon a load variation occurred on the side of the non-contact IC card.

11. The non-contact IC card reading/writing apparatus as claimed in any one of claim 4 to claim 8 wherein:

the resonant frequency of the second resonant circuit is set to a frequency range which covers a plurality of modulated subcarriers formed based upon a load variation occurred on the side of the non-contact IC card.

13. The non-contact IC card reading/writing apparatus as claimed in any one of claim 4 to claim 12 wherein:

an intermediate frequency transformer is provided between the second resonant circuit and the wireless receiver; and

the ground of the second resonant circuit is separated from the ground of the wireless receiver.