Source: http://www.google.com/patents/US7570225?dq=No.+6,411,949&ei=AUR7T-LGJqSr0AHy2aSiBg
Timestamp: 2013-12-13 11:33:40
Document Index: 797306750

Matched Legal Cases: ['art 82', 'art 12', 'art 12', 'art 32', 'art 32', 'art 32', 'art 32', 'art 42', 'art 42', 'Application No. 2006', 'Application No. 04806971']

Patent US7570225 - Antenna and non-contact tag - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inAdvanced Patent SearchPatentsAn RFID antenna that can be disposed in a space-saving manner. The RFID antenna comprises an outermost peripheral conductive line that is bent in a manner extending along sides of a generally rectangular shape having a predetermined size, and a power-feeding conductive line that is disposed close to...http://www.google.com/patents/US7570225?utm_source=gb-gplus-sharePatent US7570225 - Antenna and non-contact tagAdvanced Patent SearchPublication numberUS7570225 B2Publication typeGrantApplication numberUS 11/790,580Publication dateAug 4, 2009Filing dateApr 26, 2007Priority dateDec 14, 2004Fee statusPaidAlso published asCN101053115A, CN101053115B, DE602004024602D1, EP1826866A1, EP1826866A4, EP1826866B1, US20070200711, WO2006064540A1Publication number11790580, 790580, US 7570225 B2, US 7570225B2, US-B2-7570225, US7570225 B2, US7570225B2InventorsManabu Kai, Toru Maniwa, Takashi YamagajoOriginal AssigneeFujitsu LimitedExport CitationBiBTeX, EndNote, RefManPatent Citations (30), Non-Patent Citations (5), Referenced by (1), Classifications (17), Legal Events (2) External Links: USPTO, USPTO Assignment, EspacenetAntenna and non-contact tagUS 7570225 B2Abstract An RFID antenna that can be disposed in a space-saving manner. The RFID antenna comprises an outermost peripheral conductive line that is bent in a manner extending along sides of a generally rectangular shape having a predetermined size, and a power-feeding conductive line that is disposed close to an inner periphery of the outermost peripheral conductive line in a manner extending parallel therewith, and is electrically connected to the outermost peripheral conductive line at ends thereof, the power-feeding conductive line including a portion thereof formed with a feeder part. Therefore, the antenna fits into a rectangle having a predetermined size, such as a card size.
An RFID system in which non-contact tags (hereinafter referred to as �the RFID tags�) having identification information embedded therein are attached to respective articles or persons, thereby enabling transmission/reception of information between the persons or the articles and RFID reader/writers (hereinafter simply referred to as �the reader/writers�) using a radio signal, is expected to be applied to various fields, such as management of factory production, management of physical distribution, and management of room entrance/exit, and is coming into practical use.
The illustrated conventional folded antenna 80 comprises two dipole antennas 81 a and 81 b each having a length of approximately 150 mm and arranged close to each other in parallel, with a spacing of e.g. 10 mm therebetween. The dipole antenna 81 a and the dipole antenna 81 b are connected to each other at opposite ends thereof, and electric power is fed via a feeder part 82 formed in the center of the dipole antenna 81 a. With this arrangement, the radiation resistance R2 appearing in FIG. 14 can be made more than four times larger than the radiation resistance (72 Ω) of a single dipole antenna. Further, by changing the ratio of the line width of the dipole antenna 81 b to that of the dipole antenna 81 a as shown in FIG. 15, it is possible to adjust the radiation resistance such that it is increased to approximately 1000 Ω (see e.g. �Antenna Technology Handbook� (Ohmsha Ltd.), the Institute of Electronics, Information and Communication Engineers (IEICE), October, 1980, pp. 112-115).
However, although it is desirable for practical use that an RFID tag has a size not larger than a card size (86 mm�54 mm), for example, the conventional folded antenna requires a length of a longitudinal side thereof of approximately 150 mm for receiving a radio signal in the UHF band. The length is too large for practical use.
SUMMARY OF THE INVENTION The present invention has been made in view of the problem, and an object thereof is to provide an RFID antenna that can be disposed in a space-saving manner.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view of the arrangement of an RFID antenna according to a first embodiment.
The antenna 10 according to the first embodiment is formed by bending the folded antenna, shown in FIG. 15, into a rectangular shape, and comprises an outmost peripheral conductive line (hereinafter simply referred to as the outermost peripheral line) 11 bent in a manner extending along the sides of a rectangle having a size of approximately 72 mm�42 mm, for example, and a power-feeding conductive line (hereinafter simply referred to as the feeder line) 13 disposed close to the inner periphery of the outermost peripheral line 11 in a manner extending parallel therewith. The feeder line 13 is electrically connected to the outermost peripheral line 11 at ends thereof, and includes a portion formed with a feeder part 12. In the antenna 10 according to the first embodiment, the outermost peripheral line 11 and the feeder line 13 are formed in a manner extending bilaterally symmetrically with respect to the feeder part 12.
By configuring the antenna 10 as described above, it is possible to reduce the size of the folded antenna capable of obtaining a high radiation resistance e.g. to a card size (86 mm�54 mm).
It is preferred that the bending angle of the rectangle is set to 90�, because this makes it possible to increase the antenna size within a predetermined area. However, the bending angle may be set to an angle of e.g. 80� or 45�, which is smaller than 90�.
The antenna 10 has a size of approximately 72 mm�42 mm and a thickness of approximately 0.02 mm, for example. The sheet 21 is formed e.g. of paper or PET (polyethylene terephthalate) film. The sheet 21 has a size of approximately 86 mm�54 mm and a thickness of approximately 0.1 mm, for example.
The IC chip 22 has a size of approximately 1 mm�1 mm and a thickness of approximately 0.2 mm, for example.
The directivity of the antenna 10 according to the first embodiment is maximized when the angle φ is 90� or 270�.
Similarly to the antenna according to the first embodiment, the antenna 30 according to the second embodiment comprises an outermost peripheral line 31 that is bent in a manner extending along the sides of a rectangle having a size of approximately 72 mm�42 mm, for example, and a feeder line 33 that is disposed close to the inner periphery of the outermost peripheral line 31 in a manner extending parallel therewith, and is electrically connected to the outermost peripheral line 31 at ends thereof, the feeder line 33 including a portion formed with a feeder part 32. However, the antenna 30 according to the second embodiment is different from the antenna 10 according to the first embodiment in that the outermost peripheral line 31 and the feeder line 33 are formed in a manner extending bilaterally asymmetrically with respect to the feeder part 32.
While the directivity of the antenna 10, shown in FIG. 1, according to the first embodiment is maximized, as shown in FIG. 6, at the angle φ of 90� or 270�, the directivity of the antenna 30 according to the second embodiment, in which the outermost peripheral line 31 and the feeder line 33 are formed in a manner extending bilaterally asymmetrically with respect to the feeder part 32, is maximized, as shown in FIG. 11, at the angle φ of 45� or 225�, by adjusting the position of the feeder part 32.
Although in the above-described first and second embodiments, the description is given of the antennas 10 and 30 which can be received within the card size (86 mm�54 mm), it is possible to further reduce the antenna size.
The antenna 40 according to the third embodiment comprises an outermost peripheral line 41 that is bent in a manner extending along the sides of a rectangle having a size of approximately 42 mm�42 mm, for example, and a feeder line 43 that is disposed close to the inner periphery of the outermost peripheral line 41 in a manner extending parallel therewith, and is electrically connected to the outermost peripheral line 41 at ends thereof, the feeder line 43 including a portion formed with a feeder part 42. If the size of the antenna is reduced as in the case of the antenna 40 according to the third embodiment, the outermost peripheral line 41 suffers from a length shortage by which the outer periphery of the rectangle having a size of 42 mm�42 mm, for example, is short of a length required for receiving radio waves of 953 MHz, and hence a length corresponding to the shortage is formed by bending the outermost peripheral line 41 into the inside of the rectangle, as illustrated by lines 41 a. Further, the antenna 40 has an impedance-adjusting inductor 44 for performing impedance matching with an IC chip (not shown) connected to the feeder part 42. The inductor 44 is disposed in an area inside the rectangle. In the antenna 40 according to the third embodiment, the inductor 44 is connected to two opposite sides of a rectangular shape into which the feeder line 43 is bent. Compared with the inductor 14 of the antenna 10 according to the first embodiment, the inductor 44 has no bent portion so as to eliminate loss due to current concentration.
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