Power transmission system IC card and information communication system using IC card

• US 6,321,067 B1
• Filed: 09/15/1997
• Issued: 11/20/2001
• Est. Priority Date: 09/13/1996
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Nagai, Kenji, Suga, Takashi, Hayashi, Yoshihiko, Yoshino, Ryouzou
• Primary Examiner(s): Maung, Nay
• Assistant Examiner(s): Trinh, Sonny
• Application Number:
  US08/929,060
• Time in Patent Office: 1,527 Days
• Field of Search: 340/825.54, 340/825.69, 340/825.72, 340/10.1, 340/10.3, 455/572, 455/127, 455/557, 455/558, 455/41, 455/73, 455/343, 455/573, 455/80, 235/492, 235/487, 342/51, 343/895, 343/867, 343/701
• US Class Current: 455/41.2
• CPC Class Codes: G06K 19/0701 at least one of the integrated circuit chips comprising an arrangement for power management
• CPC Class Codes: G06K 19/0715 the arrangement including means to regulate power transfer to the integrated circuit
• CPC Class Codes: G06K 19/0723 the record carrier comprising an arrangement for non-contact communication, e.g. wireless communication circuits on transponder cards, non-contact smart cards or RFIDs
• CPC Class Codes: G06K 19/0726 the arrangement including a circuit for tuning the resonance frequency of an antenna on the record carrier
• 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: G07C 9/28 the pass enabling tracking or indicating presence
• CPC Class Codes: H01Q 1/2225 used in active tags, i.e. provided with its own power source or in passive tags, i.e. deriving power from RF signal
• CPC Class Codes: H01Q 7/005 with variable reactance for tuning the antenna
• CPC Class Codes: H02J 50/005 Mechanical details of housing or structure aiming to accommodate the power transfer means, e.g. mechanical integration of coils, antennas or transducers into emitting or receiving devices
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/20 using microwaves or radio frequency waves
• CPC Class Codes: H02J 50/80 involving the exchange of data, concerning supply or distribution of electric power, between transmitting devices and receiving devices
• CPC Class Codes: H02J 50/90 involving detection or optimisation of position, e.g. alignment

Abstract

The present invention comprises a power transmission system, an IC card, and an information communication system using an IC card. In the power transmission system, power is transmitted by radio from the power transmission device to the IC card. In the IC card, the transmitted induced power is converted into a DC voltage, the transmitted induced power or a voltage corresponding to the induced power is detected, and a desired DC voltage to be suppled to the internal circuit is obtained in controlling resistance the detected induced power or the voltage corresponding to the induced power.

Claims

1. A power transmission system in which power is transmitted by radio wave from a power transmission device to an IC card, said IC card comprising:

a converter circuit including a first antenna having a resonance circuit for receiving said transmitted radio wave and a rectifier circuit which converts an induced power received in said antenna into a DC voltage in rectifying it, the DC voltage being supplied to an internal circuit,

a detector circuit portion for detecting one of the induced power obtained from said first antenna of the converter circuit and a voltage corresponding to said induced power, and

a transmitting unit which transmits an information by a radio wave to the power transmission device, the information concerning with said one of the induced power and the voltage detected by said detector circuit portion; and

said power transmission device comprising;

a receiving unit which receives said information by the radio wave being transmitted from the transmitting unit of the IC card,

a control power supply circuit which controls an output of high frequency power based on the information received by receiving unit, and

a power transmitting unit having a second antenna for transmitting the output of high frequency power by the radio wave, the output of high frequency power being controlled by said control power supply circuit.

2. A power transmission system in which power is transmitted by radio wave from a power transmission device to an IC card, said IC card comprising;

a converter circuit including a first antenna having a resonance circuit for receiving said transmitted radio wave and a rectifier circuit which converts induced power received in said antenna into a DC voltage in rectifying it,

an internal circuit to be supplied with the DC voltage which is converted in said rectifier circuit of said convertor circuit,

a detector circuit which detects one of said induced power and a voltage corresponding to said induced power, and

a transmission unit which transmits an information by a radio wave to said power transmission device, the information concerning with said one of the induced power and the voltage detected by the detector circuit; and

said power transmission device comprising;

a receiving unit which receives said information by the radio wave being transmitted from the transmission unit of the IC card,

a control power supply circuit which controls an output of high frequency power based on the information received by the receiving unit, and

a power transmitting unit having a second antenna for transmitting the output of high frequency power by the radio wave, the output of high frequency power being controlled by said control power supply circuit.

3. A power transmission system in which power is transmitted by radio wave having a predetermined high frequency from a power transmission device to an IC card, said IC card comprising:

an antenna having a resonance circuit which comprises by connecting in parallel with a coil and a capacitor for receiving said transmitted radio wave and generating an induced voltage;

a rectifier circuit portion which converts an induced voltage generated from said antenna into a DC voltage in rectifying it;

a detector circuit portion which detects an information corresponding to relative distance between the IC card and the power transmission device;

a variable resonance frequency control circuit which controls the induced voltage generated from said antenna in accordance with shifting resonance frequency of said resonance circuit by varying one of capacitance of the capacitor and inductance of the coil based on said information corresponding to relative distance detected by the detector circuit portion to control the DC voltage obtained from said rectifier circuit; and

an internal circuit to be supplied with a controlled DC voltage being obtained from said rectifier circuit portion.

4. A power transmission system comprising:

an IC card comprising;

a converter circuit including a first antenna having a resonance circuit for receiving radio wave being transmitted from a power transmission device and a rectifier circuit which converts an induced power received in said antenna into a DC voltage in rectifying it, and

an internal circuit to be supplied with the DC voltage which is converted in said rectifier circuit of said converter circuit; and

said power transmission device comprising;

a detector unit which detects an information corresponding to relative distance between the IC card and the power transmission device,

a control power supply circuit which controls by varying a level of a high frequency power based on the information corresponding to relative distance detected by the detector unit and generates a controlled level of the high frequency power, and

a power transmitting unit having a second antenna for transmitting the controlled level of the high frequency power being generated from said control power supply circuit to the first antenna of the converter circuit of the IC card by the radio wave.

5. A power transmission system as claimed in claim 4, wherein the detector unit is formed by a distance detector unit which detects a relative distance information between the IC card and the power transmission device.

6. A power transmission system as claimed in claim 4, wherein the detector unit is formed by a distance detector unit which detects a relative distance information between the IC card and the power transmission device by using one of infrared rays and ultrasonic rays.

7. A power transmission system as claimed in claim 4, wherein the power transmission device is formed by a reader and/or writer.