Loop antenna and contactless IC card read/write apparatus
First Claim
1. A loop antenna having an electromagnetic wave shield over at least one side of the loop antenna, the electromagnetic wave shield comprising:
- a plurality of electric conductors;
a ground contact, grounding the plurality of electric conductors; and
a lead wire, connecting the plurality of electric conductors to the ground contact;
wherein the plurality of electric conductors are electrically connected via the lead wire to the ground contact and arranged so that the paths of the respective electric conductors from any of their given points to the ground contact via the lead wire are determined uniformly.
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Accused Products
Abstract
To provide a loop antenna capable of attenuating the distant electric field with the attenuation of the magnetic flux in the vicinity of an electromagnetic wave restrained, and a contactless IC card read/write apparatus.
A loop antenna 10 has an electromagnetic wave shield 1 over at least one side of the loop antenna, the electromagnetic wave shield 1 comprising a plurality of electric conductors 2, a ground contact 3 for grounding the plurality of electric conductors and a lead wire 4 for connecting the plurality of electric conductors 2 to the ground contact 3. The plurality of electric conductors 2 are electrically connected via the lead wire 4 to the ground contact 3 and the plurality of electric conductors 2 are arranged so that the paths of the respective electric conductors 2 from any of their given points to the ground contact 3 via the lead wire 4 are determined uniformly.
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Citations
22 Claims
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1. A loop antenna having an electromagnetic wave shield over at least one side of the loop antenna, the electromagnetic wave shield comprising:
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a plurality of electric conductors;
a ground contact, grounding the plurality of electric conductors; and
a lead wire, connecting the plurality of electric conductors to the ground contact;
wherein the plurality of electric conductors are electrically connected via the lead wire to the ground contact and arranged so that the paths of the respective electric conductors from any of their given points to the ground contact via the lead wire are determined uniformly. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 18, 19, 20)
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2. A loop antenna having an electromagnetic wave shield over at least one side of the loop antenna, the electromagnetic wave shield comprising:
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a plurality of electric conductors;
a ground contact, grounding the plurality of electric conductors; and
a lead wire, connecting the plurality of electric conductors to the ground contact;
wherein the plurality of electric conductors are connected via the lead wire to the ground contact through such an electric connection as not to form a closed loop structure.
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- 15. A loop antenna wherein an electromagnetic wave shield is provided with a plurality of electric conductors so arranged that the paths of the respective electric conductors from any of their given points to a ground contact are determined uniformly.
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16. A loop antenna wherein an electromagnetic wave shield is provided with a plurality of electric conductors so arranged that the electric conductors are connected to a ground contact through such an electric connection as not to form a closed loop structure.
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21. A contactless IC card read/write apparatus comprising:
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a loop antenna, supplying electric power and transmitting data to a contactless IC card by electromagnetic induction and receiving data from the contactless IC card through load changes and a read/write apparatus connected to the loop antenna;
wherein an electromagnetic wave shield is disposed in the direction in which the loop antenna communicates with the contactless IC card and arranged so that paths of a plurality of electric conductors from any of their given points to a ground contact are determined uniformly.
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22. A contactless IC card read/write apparatus comprising:
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a loop antenna, supplying electric power and transmitting data to a contactless IC card by electromagnetic induction and receiving data from the contactless IC card through load changes and a read/write apparatus connected to the loop antenna;
wherein an electromagnetic wave shield is disposed in the direction in which the loop antenna communicates with the contactless IC card and arranged so that a plurality of electric conductors are connected to a ground contact through such an electric connection as not to form a closed loop structure.
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Specification