Tag device, antenna, and portable card

• US 20070262871A1
• Filed: 07/06/2007
• Published: 11/15/2007
• Est. Priority Date: 01/07/2005
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Kai, Manabu, Maniwa, Toru, Yamagajo, Takashi
• Granted Patent: US 7,880,680 B2
• Time in Patent Office: Days
• US Class Current: 340/572.700
• CPC Class Codes: G06K 19/07771 the record carrier comprising means for minimising adverse effects on the data communication capability of the record carrier, e.g. minimising Eddy currents induced in a proximate metal or otherwise electromagnetically interfering object
• 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

Abstract

A tag device that performs high-quality radio communication without radio wave radiation or receiving characteristics being deteriorated near a person'"'"'s body and without hindering communication by another IC tag. A main loop section sends and receives radio waves. The main loop section is a metal foil and has the shape of a long thin loop. The area of the main loop section is smaller than the area of a dielectric substrate. The main loop section covers part of surfaces of the dielectric substrate and part of sides of the dielectric substrate so as to put the dielectric substrate inside the loop. The main loop section is mounted in a horizontal direction of the dielectric substrate. Each of capacitive load sections is a metal foil and has a load corresponding to a capacitance component. The capacitive load sections are located at both end portions of the main loop section which covers part of the front side of the dielectric substrate and are located at both end portions of the main loop section which covers part of the reverse side of the dielectric substrate. A control unit is connected to the main loop section and controls information via the radio waves.

Claims

1. A tag device for performing radio communication, the device comprising:

an antenna unit including;

a main loop section being a loop-like metal foil mounted on a surface of a dielectric substrate for sending and receiving radio waves, and

capacitive load sections being metal foils connected to the main loop section and each having a load corresponding to a capacitance component; and

a control unit connected to the main loop section for controlling information via the radio waves.

2. The tag device according to claim 1, wherein:

the main loop section has the shape of a long thin loop, is smaller than the dielectric substrate in area, covers part of surfaces of the dielectric substrate and part of sides-of the dielectric substrate so as to put the dielectric substrate inside the loop, and is mounted in a horizontal direction of the dielectric substrate; and

the capacitive load sections are located at both end portions of the main loop section which covers part of a front side of the dielectric substrate and at both end portions of the main loop section which covers part of a reverse side of the dielectric substrate.

3. The tag device according to claim 1, wherein:

the main loop section has the shape of a long thin loop, is smaller than the dielectric substrate in area, covers part of surfaces of the dielectric substrate and part of sides of the dielectric substrate so as to put the dielectric substrate inside the loop, and is mounted in the direction of an oblique line of the dielectric substrate; and

the capacitive load sections are located at both end portions of the main loop section which covers part of a front side of the dielectric substrate and at both end portions of the main loop section which covers part of a reverse side of the dielectric substrate.

4. The tag device according to claim 1, wherein when the tag device is located near a person'"'"'s body, loop-like electric current distribution is created between a surface of the person'"'"'s body and the main loop section by an electric current which runs through the main loop section and the antenna unit functions as a loop antenna via the surface of the person'"'"'s body.

5. The tag device according to claim 1, wherein by connecting the capacitive load sections to the main loop section in the antenna unit, a band corresponding to electric field strength of the radio waves sent or received by the main loop section is made wide.

6. The tag device according to claim 1, wherein:

impedance of the main loop section can be changed by changing area of the capacitive load sections; and

the capacitive load sections the area of which is adjusted so as to make impedance of the control unit match the impedance of the main loop section are located on the dielectric substrate.

7. The tag device according to claim 1, wherein when the tag device is located near an object which interferes with radiation or receiving of the radio waves, the main loop section is located on the dielectric substrate so that the main loop section is distant from a position of the object.

8. The tag device according to claim 1, wherein when the tag device is located near an apparatus which performs electromagnetic induction, the main loop section is located on the dielectric substrate so as not to interrupt magnetic flux produced by the electromagnetic induction.

9. An antenna for radiating and receiving radio waves, the antenna comprising:

a main loop section being loop-like metal for sending and receiving the radio waves; and

capacitive load sections being metal connected to the main loop section and each having a load corresponding to a capacitance component.

10. The antenna according to claim 9, wherein the capacitive load sections are connected perpendicularly to both end portions of the loop-like main loop section to form a structure in the shape of the letter H.

11. The antenna according to claim 9, wherein end portions of the capacitive load sections are connected upward and downward to both end portions of the loop-like main loop section at acute angles to form a structure in the shape of the letter N.

12. The antenna according to claim 9, wherein if the antenna is mounted on a dielectric substrate:

the main loop section has the shape of a long thin loop, is smaller than the dielectric substrate in area, covers part of surfaces of the dielectric substrate and part of sides of the dielectric substrate so as to put the dielectric substrate inside the loop, and is mounted in a horizontal direction of the dielectric substrate; and

the capacitive load sections are located at both end portions of the main loop section which covers part of a front side of the dielectric substrate and at both end portions of the main loop section which covers part of a reverse side of the dielectric substrate.

13. The antenna according to claim 9, wherein if the antenna is mounted on a dielectric substrate:

the main loop section has the shape of a long thin loop, is smaller than the dielectric substrate in area, covers part of surfaces of the dielectric substrate and part of sides of the dielectric substrate so as to put the dielectric substrate inside the loop, and is mounted in the direction of an oblique line of the dielectric substrate; and

the capacitive load sections are located at both end portions of the main loop section which covers part of a front side of the dielectric substrate and at both end portions of the main loop section which covers part of a reverse side of the dielectric substrate.

14. The antenna according to claim 9, wherein when the antenna is located near a person'"'"'s body, loop-like electric current distribution is created between a surface of the person'"'"'s body and the main loop section by an electric current which runs through the main loop section and the antenna functions as a loop antenna via the surface of the person'"'"'s body.

15. The antenna according to claim 9, wherein by connecting the capacitive load sections to the main loop section, a band corresponding to electric field strength of the radio waves sent or received by the main loop section wide is made wide.

16. The antenna according to claim 9, wherein:

impedance of the main loop section can be changed by changing area of the capacitive load sections; and

if a control unit for controlling information via the radio waves is connected to the main loop section, the area of the capacitive load sections is adjusted so as to make impedance of the control unit match the impedance of the main loop section.

17. The antenna according to claim 9, wherein when the antenna is located near an object which interferes with radiation or receiving of the radio waves, the main loop section is connected to the capacitive load sections so that the main loop section is distant from a position of the object.

18. The antenna according to claim 9, wherein when the antenna is located near an apparatus which performs electromagnetic induction, the main loop section is connected to the capacitive load sections so as not to interrupt magnetic flux produced by the electromagnetic induction.

19. A portable card for performing radio communication, the card comprising:

an antenna unit including;

a main loop section being a loop-like metal foil mounted on a surface of a dielectric substrate for sending and receiving radio waves, and

capacitive load sections being metal foils connected to the main loop section and each having a load corresponding to a capacitance component;

a control unit connected to the main loop section for controlling information via the radio waves; and

a member having the shape of a portable card for housing the antenna unit and the control unit.

20. The portable card according to claim 19, wherein:

the main loop section has the shape of a long thin loop, is smaller than the dielectric substrate in area, covers part of surfaces of the dielectric substrate and part of sides of the dielectric substrate so as to put the dielectric substrate inside the loop, and is mounted in a horizontal direction of the dielectric substrate; and

the capacitive load sections are located at both end portions of the main loop section which covers part of a front side of the dielectric substrate and at both end portions of the main loop section which covers part of a reverse side of the dielectric substrate.

21. The portable card according to claim 19, wherein:

the main loop section has the shape of a long thin loop, is smaller than the dielectric substrate in area, covers part of surfaces of the dielectric substrate and part of sides of the dielectric substrate so as to put the dielectric substrate inside the loop, and is mounted in the direction of an oblique line of the dielectric substrate; and

the capacitive load sections are located at both end portions of the main loop section which covers part of a front side of the dielectric substrate and at both end portions of the main loop section which covers part of a reverse side of the dielectric substrate.

22. The portable card according to claim 19, wherein when the portable card is located near a person'"'"'s body, loop-like electric current distribution is created between a surface of the person'"'"'s body and the main loop section by an electric current which runs through the main loop section and the antenna unit functions as a loop antenna via the surface of the person'"'"'s body.

23. The portable card according to claim 19, wherein by connecting the capacitive load sections to the main loop section in the antenna unit, a band corresponding to electric field strength of the radio waves sent or received by the main loop section is made wide.

24. The portable card according to claim 19, wherein:

impedance of the main loop section can be changed by changing area of the capacitive load sections; and

the capacitive load sections the area of which is adjusted so as to make impedance of the control unit match the impedance of the main loop section are located on the dielectric substrate.

25. The portable card according to claim 19, wherein when the portable card is located near an object which interferes with radiation or receiving of the radio waves, the main loop section is located on the dielectric substrate so that the main loop section is distant from a position of the object.

26. The portable card according to claim 19, wherein when the portable card is located near an apparatus which performs electromagnetic induction, the main loop section is located on the dielectric substrate so as not to interrupt magnetic flux produced by the electromagnetic induction.