Communication device

• US 6,869,019 B1
• Filed: 09/08/2000
• Issued: 03/22/2005
• Est. Priority Date: 10/13/1999
• Status: Expired due to Term

• Current Assignee: ROHM Co., Ltd.
• Original Assignee: ROHM Co., Ltd.
• Inventors: Ueda, Takashi, Nagi, Katsutoshi
• Primary Examiner(s): Le, Thien M.
• Assistant Examiner(s): TRAIL, ALLYSON NEEL
• Application Number:
  US10/089,937
• Time in Patent Office: 1,656 Days
• Field of Search: 235/492, 235/449, 235/462.47, 235/451, 235/462.45, 235/472.01, 235/382, 235/385, 235/375, 235/380, 235/441, 361/737, 361/818
• US Class Current: 235/492
• 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 19/07749 the record carrier being capable of non-contact communication, e.g. constructional details of the antenna of a non-contact smart card
• 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 1/243 with built-in antennas
• CPC Class Codes: H01Q 1/245 with means for shaping the antenna pattern, e.g. in order to protect user against rf exposure
• CPC Class Codes: H01Q 1/48 Earthing means; Earth screens; Counterpoises
• CPC Class Codes: H01Q 1/52 Means for reducing coupling between antennas; Means for reducing coupling between an antenna and another structure absorbing means H01Q17/00
• CPC Class Codes: H01Q 1/526 Electromagnetic shields
• CPC Class Codes: H01Q 17/001 for modifying the directional characteristic of an aerial
• 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
• CPC Class Codes: H04B 1/3838 Arrangements for reducing RF exposure to the user, e.g. by changing the shape of the transceiver while in use

Abstract

In a communication device, electric circuits other than an antenna are enclosed in a shielding member made of a material that shuts off radio waves, and the antenna is enclosed by disposing in front thereof a radio wave absorbing member that attenuates radio waves in a predetermined frequency band. Thus, unnecessary electromagnetic emission is alleviated while satisfactory communication quality is secured.

Claims

1. A communication device that supplies electric power to a communication partner and communicates therewith by electromagnetic induction on a non-contact basis,

wherein electric circuits other than an antenna are enclosed in a first shielding member made of a material that shuts off, reflects, or absorbs radio waves, and the antenna is enclosed in a second shielding member of which a portion facing a front face of the antenna is made of a material that attenuates radio waves in a predetermined frequency band.

2. A communication device as claimed in claim 1, wherein the portion of the second shielding member facing the front face of the antenna has such a frequency response as to permit passage of radio waves only in a frequency band centered around a frequency used for communication.

3. A communication device as claimed in claim 1, wherein the first shielding member has a double structure by being composed of an inner layer made of a material that absorbs radio waves and an outer layer made of a material that reflects radio waves.

4. A communication device as claimed in claim 1, wherein a filter is inserted in a line that electrically connects the antenna to other electric circuits.

5. A communication device as claimed in claim 4, wherein the filter has a frequency response identical with a frequency response of the portion of the second shielding member facing the front face of the antenna.

6. A communication device as claimed in claim 1, wherein a portion of the first shielding member is shared as a portion of the second shielding member other than the portion thereof facing the front face of the antenna.

7. A communication device as claimed in claim 6, wherein the first shielding member has a recess formed therein so as to sink inward, the antenna is arranged in the recess, and the second shielding member is arranged so as to cover an opening of the recess.

8. A communication device that supplies electric power to a communication partner and communicates therewith by electromagnetic induction on a non-contact basis,

wherein electric circuits other than an antenna are enclosed in a first shielding member made of a material that shuts off, reflects, or absorbs radio waves, and the antenna is enclosed in a second shielding member that has an opening formed in a portion thereof facing a front face of the antenna so as to attenuate radio waves in a frequency band corresponding to an area of the opening.

9. A communication device as claimed in claim 8, wherein the first shielding member has a double structure by being composed of an inner layer made of a material that absorbs radio waves and an outer layer made of a material that reflects radio waves.

10. A communication device as claimed in claim 8, wherein a filter is inserted in a line that electrically connects the antenna to other electric circuits.

11. A communication device as claimed in claim 10, wherein the filter has a frequency response identical with a frequency response of the portion of the second shielding member facing the front face of the antenna.

12. A communication device as claimed in claim 8, wherein a portion of the first shielding member is shared as a portion of the second shielding member other than the portion thereof facing the front face of the antenna.

13. A communication device as claimed in claim 12, wherein the first shielding member has a recess formed therein so as to sink inward, the antenna is arranged in the recess, and the second shielding member is arranged so as to cover an opening of the recess.

14. A communication device as claimed in claim 8, wherein the opening formed in the second shielding member is formed in such a way that the portion of the second shielding member facing the front face of the antenna has such a frequency response as to attenuate radio waves in a frequency band below and including an upper limit of frequencies that need to be attenuated.

15. A communication device as claimed in claim 14, wherein the second shielding member has four quadrilateral, openings formed therein in a grid-like arrangement.