Patent Grant
9559421
This is a National Stage of International Application No. PCT/JP2012/068484 filed Jul. 20, 2012 (claiming priority based on Japanese Patent Application No. 2011-160900 filed Jul. 22, 2011 and Japanese Patent Application No. 2012-079300 filed Mar. 30, 2012), the contents of which are incorporated herein by reference in their entirety.
The present invention relates to an antenna used for magnetic-field-inductive, small-power wireless communications, for example, RFID (radio frequency identification) in small wireless communications apparatuses such as mobile phones, particularly to an antenna for near field communications (NFC) using a communication frequency band of 13.56 MHz.
IC card systems are widely known as those for near-field wireless communications.
The antenna apparatus 280 comprises a semiconductor 70, a first filter (noise filter) 71, a matching circuit 72, and a second filter 73. The semiconductor 70 comprises a transmission circuit, a receiving circuit, a modulation circuit, a demodulation circuit, a controller, etc. An antenna resonance circuit 66 comprises the first antenna 1a for near-field wireless communications, a resonance capacitor 65, and a resistor (not shown). The resonance frequency of the antenna resonance circuit 66 is set to be an intrinsic frequency (for example, 13.56 MHz) used for communications, in which a real part of impedance of the antenna resonance circuit 66 is substantially in a short-circuited state. The antenna resonance circuit 66 is connected to the semiconductor 70 via the impedance-matching circuit 72.
An output terminal Tx connected to the modulation circuit in the transmission circuit in the semiconductor 70 is connected to the impedance-matching circuit 72 via the first filter 71 for EMC. An input terminal Rx connected to the demodulation circuit in the receiving circuit in the semiconductor 70 is connected to a connection point of the first filter 71 and the impedance-matching circuit 72 via the second filter 73 comprising series-connected resistor and capacitor.
The transmission circuit and the receiving circuit in the semiconductor 70 are controlled to be an operation state or a non-operation state by the controller. Signals having a frequency (for example, 13.56 MHz) corresponding to a tuning frequency are supplied from an oscillator to the transmission circuit, the signals being modulated according to a predetermined protocol and supplied to the antenna resonance circuit 66. The first antenna 1a for near-field wireless communications in the antenna resonance circuit 66 is magnetically coupled to the second antenna 1b for near-field wireless communications in the IC card 285 at a predetermined coupling constant, thereby transmitting signals (carrier signals) to the IC card 285. Signals (carrier signals) from the IC card 285 are received by the receiving circuit in the semiconductor 70, after suppressed by a resistor in the second filter 73.
The antenna for near-field wireless communications (hereinafter referred to simply as “antenna”) used in such system comprises, as generally shown in
In a wireless communications apparatus, a metal shield formed by a metal sheet or case, etc. is usually disposed near the antenna 1. In this case, parasitic capacitance is formed between the coil 10 and the metal shield, so that eddy current is generated in the metal shield, reducing the inductance of the coil 10, and changing the resonance frequency of the antenna 1. Further, eddy current loss is generated, making it necessary to increase electric supply to the coil 10 for compensation, resulting in increased battery consumption. In addition, the magnetic flux not contributing to communications acts as noise to other parts, likely causing troubles.
Against such problems, the attachment of a high-permeability magnetic member to a non-transmission side of an antenna is proposed (JP 2004-166175 A).
The transmission of power and data by electromagnetic induction has long been known. For example, in noncontact-charging antennas, coils formed by enameled wires are fixed to magnetic member surfaces. To handle larger power than in small-power wireless communications (for example, to supply current of about 1 A to the coils), enameled wires of about 1 mm in diameters are generally used, with coil ends not fixed for flexibility.
Antennas for small-power wireless communications constituted according to the structure of the noncontact-charging antennas have been found to suffer the following problems. Because the antennas for small-power wireless communications handle power of at most about 15 mA, conductor wires having as small diameters as 100 μm or less can be used, and the formation of coils is easy. However, when the coil ends are free, thin lead wires are easily deformed by a small external force, restricting connection methods to other circuits. Also, when the antennas are bent or disposed on curved surfaces, tension is applied to the lead wires, likely resulting in the breakage of conductor wires of the coils, and the unwinding of coils.
Though the coils can have thick conductor wires for increased strength, the coils become thick, particularly in portions overlapping the lead wires at their ends. The antennas become thicker as the conductor wires have larger diameters. When used for small wireless communications apparatuses such as mobile phones, thin, small antennas are preferable, so that substrates should have slits for receiving lead wires to prevent the thickness increase of antennas.
In applications of limited thickness such as IC card systems, coils should be as thin as possible to provide easily handleable, thin antennas resistant to breakage, etc. Thus proposed are the formation of a coil called “printed coil” on a flexible substrate by etching a metal foil or a vapor-deposited metal film in place of using a conductor wire such as an enameled wire (JP 2004-166175 A), and the production of an antenna by printing a conductive paste in a coil shape, and transferring the resultant coil-shaped conductor pattern onto an adhesive film. However, the printed coil needs a patterning step, an etching step, etc., and the transfer-printed coil needs a printing step, a transferring step, etc., resulting in more expensive coils than those constituted by conductor wires.
In addition, because the printed coil has a thickness of about 30 μm, it should be wide to have smaller electric resistance to avoid the deterioration of antenna characteristics such as a Q value, etc. Accordingly, with the same number of winding, the printed coil occupies a larger area than that of the conductor wire coil, preventing the miniaturization of antennas. The reduction of the number of winding of a coil for being received in a predetermined size results in inductance decrease and a smaller communication distance. Though the conductor pattern can be made thicker, coils become more expensive accordingly.
Accordingly, an object of the present invention is to provide an antenna, which is less expensive and lower than printed coils, etc., and easily connectable to other circuits, and comprises a conductor wire coil whose lead wires are resistant to breakage.
The antenna of the present invention comprises a coreless coil formed by winding a conductor wire, a relay member connected to the coil, and a magnetic plate member covering the coil and part of the relay member;
the relay member comprising a substrate having a notch, through which lead wires of the coil pass, and a pair of terminal members formed on the substrate, each terminal member comprising an internal terminal portion connected to an end of each lead wire, an external terminal portion connected to an external circuit, and a line portion connecting the internal terminal portion to the external terminal portion;
the coil and part of the relay member disposed on the magnetic member being fixed to a first adhesive layer on the non-transmission side of the coil; and
the internal terminal portions being positioned in a region overlapping the magnetic member, or in a region surrounded by a hole or notch of the magnetic member.
In one embodiment of the present invention, the relay member comprises a first region overlapping the magnetic member, and a second region extending from an outer periphery of the magnetic member; and the external terminal portions in the second region are exposed on the transmission surface side of the magnetic member.
In another embodiment of the present invention, the second region of the relay member is bent to the magnetic member side, so that the external terminal portions appear on a non-transmission surface side of the magnetic member.
In a further embodiment of the present invention, both of the coil and the relay member are covered with a second adhesive layer provided on the transmission side of the coil.
In a still further embodiment of the present invention, a protective layer of a resin film is attached to the non-transmission surface side of the magnetic member.
In a still further embodiment of the present invention, the relay member extends to an inner periphery of the coil.
In a still further embodiment of the present invention, the magnetic member is constituted by pluralities of pieces attached to the first adhesive layer for flexibility.
In a still further embodiment of the present invention, pluralities of the pieces are formed by dividing the magnetic member along its slits, through-holes or recesses.
The embodiments of the present invention will be explained referring to the attached drawings, and it should be noted that explanation concerning an antenna in each embodiment is applicable to antennas in other embodiments unless otherwise mentioned. Particularly, explanations of materials of parts are common in any embodiments.
[1] First Embodiment
(1) Structure
The antenna 1 shown in
The coil 10 formed by a spirally wound conductor wire has a lead portion, in which a lead wire 11a extending from an inside end of the coil 10 and a lead wire 11b extending from an outside end of the coil 10 are positioned. Because the relay member 20 is disposed outside the coil 10 at a position close to the lead portion of the coil 10 as shown in
For example, when a flat coil of 4 turns is formed by winding a self-bonding enameled wire as shown in
The relay member 20 shown in
The relay member 20 has a first region 20a overlapping the magnetic member 30, and a second region 20b extending from a periphery of the magnetic member 30. The relay member 20 is provided with the internal terminal portions 21a, 21b in the first region 20a, which does not overlap the coil 10, and the external terminal portions 22a, 22b connected to the internal terminal portions 21a, 21b via the line portions 23a, 23b in the second region 20b. The external terminal portions 22a, 22b are preferably exposed on the transmission surface side of the magnetic member 30.
Because the internal terminal portions 21a, 21b connected to the lead wires 11a, 11b of the coil 10 are covered with the magnetic member 30 or the adhesive layers 12a, 12c, the connecting portion of the lead wires 11a, 11b to the internal terminal portions 21a, 21b is protected, thereby avoiding the breakage of the lead wires 11a, 11b.
With a relay-member-integral coil 33 comprising the internal terminal portions 21a, 21b connected to the lead wires 11a, 11b of the coil 10 produced in advance, the antenna 1 can be easily connected to other circuits with the external terminal portions 22a, 22b in the projecting second region 20b of the relay member 20. The connection of the external terminal portions 22a, 22b can be achieved with a clamp metal connector, etc. in addition to soldering.
The relay member 20 has a positioning hole 152 used at the time of assembling the antenna, between the connecting lines 23a, 23b, and a pair of semi-circular notches 153, 153 on the periphery, though their positions and numbers may be changed if necessary. In other figures, the hole and notches may be omitted for simplicity.
Though the lead wires 11a, 11b may be soldered to the internal terminal portions 21a, 21b, they are preferably connected by heat press bonding, ultrasonic vibration welding, etc. In the heat press bonding, the ends of the lead wires 11a, 11b are pressed to the internal terminal portions 21a, 21b by a heated head for thermal diffusion bonding. In the ultrasonic vibration welding, the ends of the lead wires 11a, 11b are pressed to the internal terminal portions 21a, 21b by an ultrasonic vibration head for press bonding with vibration energy. Because such connecting methods do not increase the height of the internal terminal portions 21a, 21b covered with the magnetic member 30, the antenna is not made thicker. The coil 10 made integral with the relay member 20 by connecting the lead wires 11a, 11b to the internal terminal portions 21a, 21b is called relay-member-integral coil 33 below.
To prevent the breakage and cracking of the magnetic member 30, and to prevent the detachment of debris when the magnetic member 30 is broken, a resin film 15 is preferably attached as a protective layer to the non-transmission surface of the magnetic member 30 via an adhesive layer 12b as shown in
The magnetic member 30 as large as sufficiently covering the entire coil 10 and part of the relay member 20 is disposed on the non-transmission side of the coil 10 via the adhesive layer 12a. If the distance in a plane direction between a periphery of the coil 10 and a periphery of the soft-magnetic member 30 were small, the positional displacement, etc. of the soft-magnetic member 30 would have large influence on a leaked magnetic flux, resulting in the unevenness of electric characteristics (inductance, Q value, resonance frequency, etc.) among the antennas, and thus the unevenness of communicable distance. Accordingly, the distance should be sufficiently large to avoid the unevenness of electric characteristics. Specifically, the distance is preferably 0.5 mm or more.
As shown in
It is preferable that any adhesive layer 12a, 12b, 12c has sufficient flexibility to follow the shape of an object to be attached, and is easily deformable by heat pressing. The use of a single- or double-sided acrylic adhesive tape for such adhesive layer makes handling easy.
Increase in the thickness of the adhesive layer 12a determining the lamination-direction distance between the coil 10 and the magnetic member 30 leads to decrease in magnetic flux passing through the magnetic member 30, resulting in a short communication distance. On the other hand, the adhesive layers 12a, 12c should absorb the thickness difference (step) of structural members laminated. Accordingly, the thickness of the adhesive layers 12a, 12c is preferably in a range of 10-100 μm.
When a brittle member such as a sintered ferrite plate, etc. is used for the magnetic member 30, it may be broken or cracked by handling. Accordingly, the attaching of the protective layer 15 to the magnetic member 30 in advance prevents not only the breakage, etc. of the magnetic member 30, but also the detaching of its debris by breakage, etc.
The protective layer 15 is preferably constituted by a flexible insulation film of polyethylene terephthalate (PET), etc. Taking into consideration the thickness of the antenna 1, the thickness of the protective layer 15 is preferably 150 μm or less. Because the magnetic member 30 is held by the adhesive layer 12a and the protective layer 15, its debris is not detached when broken. The protective layer 15 prevents the breakage from propagating, thereby preventing decrease in the effective permeability of the magnetic member 30, and thus suppressing the variation of the resonance frequency of the antenna.
(2) Constituent Parts
(a) Coil
The coil 10 is formed by spirally winding a conductor wire 2 turns or more, with lead wires 11a, 11b extending from its internal and external ends. Though the size of the coil 10 is determined by a space in which the antenna 1 is mounted, the coil 10 preferably has as large an area as possible. Though the conductor wire may be a single- or multi-wire, it is preferably a single-wire for a smaller height of the antenna 1. Specifically, the conductor wire is preferably an enameled single-wire, more preferably an enameled wire (self-bonding wire) with a fusible overcoat. The self-bonding wire makes integration with the coil 10 easy. The diameter of the single-wire is preferably 30-100 μm. When it is less than 30 μm, the conductor wire is easily broken in winding, and the coil 10 is easily deformed at the time of assembling, resulting in difficulty in handling.
The Q value is also deteriorated. On the other hand, when it is more than 100 μm, the antenna 1 is too thick. As a result, air is trapped when the coil 10 is attached to the magnetic member 30 with an adhesive layer, resulting in lower fixing strength of the coil 10.
(b) Relay Member
When the antenna 1 should be flexible, the relay member 20 is preferably a flexible printed circuit board comprising terminal members 26a, 26b formed on a polyimide film substrate 25. When flexibility is not needed, a rigid printed circuit board formed by a glass-fiber-reinforced epoxy resin may be used. Also, a rigid-flexible printed circuit board composed of a flexible printed circuit board and a rigid printed circuit board may be used.
The relay member 20 thinner than 30 μm does not have sufficient strength. On the other hand, when it is thicker than 200 μm, an overlapping portion of the relay member 20 and the lead wires 11a, 11b of the coil 10 is too thick, resulting in a step with other portions. Though a step per se does not affect the characteristics of the antenna 1, partial thickness increase fails to provide a flat transmission surface, likely hindering the arrangement (attachment) of the antenna 1, and making the entire antenna 1 thicker when the partial thickness is to be absorbed. Accordingly, the thickness of the relay member 20 is preferably 30-200 μm, more preferably 40-150 μm.
The relay member 20 can be formed on a flexible or rigid substrate by photolithography. Specifically, a metal foil is adhered to a surface of the substrate, coated with a photoresist, and then subject to patterning exposure; a photoresist layer in other portions than a predetermined pattern is removed; the exposed metal foil is removed by chemical etching to form a conductor pattern coated with the photoresist layer; and part of the photoresist layer is removed to partially expose the metal foil at both ends of the conductor pattern, so that terminal members (conductor patterns) 26a, 26b, whose internal terminal portions 21a, 21b and external terminal portions 22a, 22b are exposed, are formed.
(c) Magnetic Member
The magnetic member 30 need only be large enough to cover the coil 10 and the lead wires 11a, 11b. The thickness of the magnetic member 30 is preferably 50-300 μm, though it may vary depending on the magnetic properties such as permeability, etc. of a soft-magnetic material used.
Soft-magnetic materials for the magnetic member 30 include soft-magnetic ferrites such as Ni ferrite, Mn ferrite, Li ferrite, etc., and soft-magnetic alloys such as Fe—Si alloys, Fe- or Co-based amorphous alloys, ultra-fine crystalline, soft-magnetic alloys, etc. When the soft-magnetic ferrite is used as a magnetic material, green sheets formed by known sheeting technologies such as a doctor blade method are formed into a predetermined shape, and sintered with or without lamination. When laminated, green sheets of different soft-magnetic ferrites may be laminated such that constituting layers have different magnetic properties. When the amorphous alloy or the ultra-fine crystalline soft-magnetic alloy is used as a magnetic material, the alloy sheet usually in a ribbon shape is cut to a predetermined shape to obtain the magnetic member 30 with or without lamination. Also, the amorphous alloy or the ultra-fine crystalline soft-magnetic alloy may be formed into powder or flakes, dispersed in a resin or a rubber, and then formed into a sheet.
[2] Second Embodiment
Though the use of a rigid sintered ferrite plate as the magnetic member 30 provides an antenna 1 having no flexibility, the use of a magnetic member 30 constituted by pluralities of separate pieces 18 provides the antenna 1 with flexibility. When the amorphous alloy or the ultra-fine crystalline soft-magnetic alloy is used as the magnetic member 30, the division of the alloy sheets to pluralities of pieces 18 suppresses the generation of eddy current. Spaces between adjacent pieces act as magnetic gaps, and the expansion of gaps between pieces is prevented by the resin film 15, thereby avoiding decrease in permeability, and thus suppressing the variation of the resonance frequency of the antenna 1. In any case, because the antenna 1 is not always disposed on a flat surface but may be disposed on a curved surface, the flexibility of a magnetic member 30 constituted by pluralities of pieces 18 increases the degree of freedom of disposing the antenna 1. The pieces 18 are held at least by the adhesive layer 12a.
Though each piece 18 preferably has a rectangular shape of 1-5 mm in each side, it may have an irregular shape to prevent breakage and its propagation. Taking into consideration the formability of slits, etc., the piece 18 more preferably has a rectangular shape of 1-5 mm×5 mm.
To obtain the magnetic member 30 constituted by pluralities of separate pieces 18, (a) after the coil 10 is attached to the magnetic member 30 to constitute an antenna, the magnetic member 30 is divided along slits 19a, 19b, through-holes or recesses (not shown) formed on at least one main surface of the magnetic member 30; (b) when the magnetic member assembly 31 and the relay-member-integral coil 33 are formed in advance, the magnetic member 30 is divided before the relay-member-integral coil 33 is attached; or (c) pluralities of magnetic material pieces 18 formed in advance are disposed closely on the adhesive layer. To form a magnetic member 30 having slits, through-holes or recesses, the slits, through-holes or recesses are formed in each green sheet of a soft-magnetic material.
[3] Third Embodiment
[4]Fourth embodiment
[5] Fifth Embodiment
[6] Sixth Embodiment
A substrate 25 for the relay member 20 has a substantially rectangular, flat shape with a pair of projections 25a, 25b on one side. A pair of terminal members 26a, 26b longitudinally extend on the substrate 25, such that each internal terminal portion 21a, 21b is positioned in each projection 25a, 25b, while external terminal portions 22a, 22b are positioned near a side (external side) opposite to the projections 25a, 25b. The internal terminal portions 21a, 21b and the external terminal portions 22a, 22b are formed on the same surface of the substrate 25. Two notches 125a, 125b are provided in a slit-shaped notch 24 between a pair of projections 25a, 25b.
As shown in
[7] Seventh Embodiment
As shown in
In the first to seventh embodiments, (a) the internal terminal portions 21a, 21b connected to the lead wires 11a, 11b of the coil 10 are surrounded by the magnetic member assembly 31 and the adhesive layer assembly 32, or (b) even when the magnetic member 30 has a notch 30a as shown in
[8] Wireless Communications Apparatus
In the case 110, the antenna 1 opposes the circuit board 126 on the side of the magnetic member 30, and the case 110 on the side of the coil 10, so that electromagnetic coupling with other antennas is not hindered. In the example shown in
The magnetic member 30 acts not only as a magnetic core but also as a magnetic yoke for the coil 10. Though a casing for the battery pack 120 is made of a metal such as aluminum, excellent antenna characteristics are kept even when the battery pack 120 is close to the antenna 1, because the magnetic member 30 prevents electromagnetic interference between the coil 10 and the metal casing of the battery pack 120.
[9] Assembling Method of Antenna
Referring to
A magnetic member assembly 31 is received in each recess 216, with a protective layer 15 on the upper side and an adhesive layer 12a on the lower side. A surface of the adhesive layer 12a in the magnetic member assembly 31 received in each recess 216 is on the same level as or slightly higher than a surface of the assembling jig 300, on which the positioning pins 310 are provided.
A relay-member-integral coil 33 assembled in advance is attached to a surface of the adhesive layer 12a. A coil-winding jig (not shown) used for assembling the relay-member-integral coil 33 comprises a flange, a rectangular-cross-sectioned core projecting from a center of the flange, and a recess receiving the relay member 20. A conductor wire is wound around the rectangular-cross-sectioned core to form a rectangular coil 10, and end portions of the coil 10 are led to the recess of the flange, and cut to a predetermined length to form lead wires 11a, 11b. The relay member 20 is disposed in the recess with the internal terminal portions 21a, 21b on the upper side, and the lead wires 11a, 11b of the coil 10 are then fused to the internal terminal portions 21a, 21b to produce a relay-member-integral coil 33.
The coil-winding jig comprises positioning pores each corresponding to each positioning pin 310 of the assembling jig 300, and a pushing pin for removing the relay-member-integral coil 33. With the relay-member-integral coil 33 attached to the coil-winding jig opposing the magnetic member assembly 31, the positioning pins 310 of the assembling jig 300 are inserted into the positioning pores of the coil-winding jig, and the relay-member-integral coil 33 is pushed onto the adhesive layer 12a by the pushing pin of the coil-winding jig to attach the coil 10 and the relay member 20 to the adhesive layer 12a. Thereafter, the coil-winding jig is detached.
As shown in
The present invention will be explained in more detail referring to Examples below without intention of restricting the present invention thereto.
A self-bonding enameled wire of 80 μm in diameter was wound 4 turns to produce a rectangular, flat coil 10 of 35 mm in long side and 25 mm in short side. Used for the relay member 20 was a flexible polyimide film substrate of 100 μm in thickness and 10 mm×10 mm in outer size. Each adhesive layer was a double-sided acrylic adhesive tape, adhesive layers 12a, 12b being 30 μm in thickness, and an adhesive layer 12c being 100 μm in thickness. Used for the protective layer 15 was a PET film of 30 μm in thickness.
Used for the magnetic member 30 was a rectangular sintered ferrite plate having of 160 μm in thickness, 40 mm in long side and 30 mm in short side. The sintered ferrite plate had a composition (100% by mol in total) comprising 48.5% by mol of Fe2O3, 20% by mol of ZnO, 22.7% by mol of NiO, and 8.8% by mol of CuO, and initial permeability of 180.
Using these parts, the antenna shown in
An antenna having the basic structure shown in
After a 70-μm-thick relay member 20 comprising a flexible polyimide substrate was laminated on the coil 10, a region of the relay member 20 including projections 25a, 25b was attached to the adhesive layer 12c. The lead wires 11a, 11b of the coil 10 were drawn from a slit-shaped notch 24 of the relay member 20, and their end portions were soldered to the internal terminal portions 21a, 21b of the relay member 20.
A square-shaped magnetic member assembly 31 of 22 mm in each side, which comprised a 200-μm-thick magnetic member 30 (sintered ferrite plate having the same composition as in Example 1), and a 100-μm-thick adhesive layer 12a, were overlapped and attached to the relay member 20 and the coil 10 under pressure. The magnetic member 30 had a notch 30a at a position corresponding to the internal terminal portions 21a, 21b of the relay member 20. The resultant antenna 1 was 33 mm in longitudinal length including the relay member 20, 22 mm in transverse length, and 0.7 mm in maximum thickness (excluding a parting paper), having self-inductance of 2.3 μH.
Communications between the antenna and an IC tag were conducted with an evaluation system shown in
The use of a coil formed by a conductor wire such as an enameled wire, and a relay member having internal terminal portions and external terminal portions without overlapping the coil, with lead wires of the coil connected to the internal terminal portions, provides an antenna for near-field wireless communications, which has low height without too thick connecting portions to the lead wires, and is easily connectable to other circuits. Because the coil and part of the relay member disposed on the magnetic member are fixed to the first adhesive layer, and because the internal terminal portions are positioned in a region overlapping the magnetic member, or in a region surrounded by a hole or notch of the magnetic member, the connecting portions of the lead wires to the relay member are so protected that the lead wires are not easily broken. Further, the division of the magnetic member to pluralities of pieces provides a flexible antenna capable of easily following a curved surface.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2011-160900 | Jul 2011 | JP | national |
| 2012-079300 | Mar 2012 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2012/068484 | 7/20/2012 | WO | 00 | 1/22/2014 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2013/015222 | 1/31/2013 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 6380834 | Canzano | Apr 2002 | B1 |
| 6412702 | Ishikawa | Jul 2002 | B1 |
| 7152803 | Stromberg | Dec 2006 | B2 |
| 7495625 | Endo et al. | Feb 2009 | B2 |
| 7712672 | Takahashi et al. | May 2010 | B2 |
| 8169286 | Hasegawa et al. | May 2012 | B2 |
| 8188826 | Okada | May 2012 | B2 |
| 8188933 | Nakamura et al. | May 2012 | B2 |
| 8378774 | Okada | Feb 2013 | B2 |
| 20030020583 | Hui | Jan 2003 | A1 |
| 20050092836 | Kudo | May 2005 | A1 |
| 20050162331 | Endo et al. | Jul 2005 | A1 |
| 20050270745 | Chen | Dec 2005 | A1 |
| 20070030659 | Suzuki | Feb 2007 | A1 |
| 20070095913 | Takahashi et al. | May 2007 | A1 |
| 20080197960 | Hasegawa et al. | Aug 2008 | A1 |
| 20090001930 | Pohjonen | Jan 2009 | A1 |
| 20090015197 | Sogabe | Jan 2009 | A1 |
| 20100156735 | Nakamura et al. | Jun 2010 | A1 |
| 20130057375 | Ankyu | Mar 2013 | A1 |
| Number | Date | Country |
|---|---|---|
| 1619572 | May 2005 | CN |
| 1816945 | Aug 2006 | CN |
| 101286411 | Oct 2008 | CN |
| 101345437 | Jan 2009 | CN |
| 201655982 | Nov 2010 | CN |
| 2002-373319 | Dec 2002 | JP |
| 2004-166175 | Jun 2004 | JP |
| 2006-164083 | Jun 2006 | JP |
| 2006-174223 | Jun 2006 | JP |
| 2010-200061 | Sep 2010 | JP |
| 5024263 | Sep 2012 | JP |
| 2006036012 | Apr 2006 | WO |
| Entry |
|---|
| Communication dated Dec. 3, 2014, issued by the State Intellectual Property Office of the People's Republic of China in corresponding Chinese Application No. 201280036144.1. |
| International Search Report of PCT/JP2012/068484 dated Oct. 23, 2012. |
| Number | Date | Country | |
|---|---|---|---|
| 20140168026 A1 | Jun 2014 | US |
