JP4085597B2

JP4085597B2 - Antenna coil

Info

Publication number: JP4085597B2
Application number: JP2001144907A
Authority: JP
Inventors: 貴則遠藤; 隆土田; 誠朗八幡
Original assignee: Mitsubishi Materials Corp
Current assignee: Mitsubishi Materials Corp
Priority date: 2001-05-15
Filing date: 2001-05-15
Publication date: 2008-05-14
Anticipated expiration: 2021-05-15
Also published as: JP2002344226A

Description

【０００１】
【発明の属する技術分野】
本発明は、ＲＦＩＤ（無線周波数識別：Radio Frequency Identification）技術又はＥＡＳ（電子式物品監視：Electronic Article Sureillannce）技術を用いた識別タグに用いられるアンテナコイルに関するものである。
【０００２】
【従来の技術】
従来、ＲＦＩＤ技術又はＥＡＳ技術を用いたタグとして、アンテナコイルに情報を記憶したＩＣチップ又は共振用のコンデンサを電気的に接続した識別タグが知られている。これらの識別タグは、アンテナコイルに質問器の送受信アンテナから所定の周波数の電波を発信することによりタグを活性化し、電波のデータ通信による読出しコマンドに応じてＩＣチップに記憶された情報を読みとることにより、又は特定周波数の電波に対して共振するか否かによりその物品を識別又は監視するように構成されたものが知られている。
これらの識別タグに用いられる従来のアンテナコイルとして、表面が絶縁層にて被覆された導線を略正方形の渦巻き状に巻回してベース板に貼付けることにより形成されたものや、或いは図９に示すようにベース板１に積層したアルミニウム箔や銅箔等の導電層をエッチング法若しくは打抜き法等により不要部分を除去して略正方形の渦巻き状のコイル本体２を形成したものが知られている。
【０００３】
しかし、図９に示すアンテナコイルでは磁束が図の矢印で示すようにベース板１を上下に貫通する方向に生じ、そのアンテナコイルを金属製の物品に密着させると、アンテナコイルに向って発信された電波がそのベース板１を貫通し更に金属製物品を貫通する。このため、その貫通する磁束により金属部分に渦電流が生じ、その渦電流が影響を与えてアンテナコイルが正常に作動しなくなる問題点があった。また、仮に作動したとしてもその損失が増してアンテナコイルの作動距離が著しく短くなる不具合があった。
この点を解消するために、図８に示すように板状又は円柱状等に形成された磁芯部材６と、この磁芯部材６に螺旋状に巻回された導体７とを有するアンテナコイルが知られている。この図８に示すアンテナコイルでは、磁束が図の矢印で示すように磁芯部材６の軸芯方向に生じるので、このアンテナコイルを金属製の物品に取付けても、アンテナコイルに向って発信された電波が金属製物品を貫通することはなく、アンテナコイルが正常に作動することが期待されている。
【０００４】
【発明が解決しようとする課題】
しかし、図８に示すアンテナコイルは、磁芯部材６の外周面に導体７を巻回することにより製作されるので、その巻線作業が比較的煩雑で量産性に欠ける不具合があった。また、磁芯部材６の外周面に導体７を巻回するため、アンテナコイル全体が比較的厚いものになり、このアンテナコイルを物品の表面に取付けると、そのアンテナコイルが物品から比較的大きく突出する問題点があった。
本発明の目的は、金属製の物品に密着させても確実に作動するとともに、厚さを極めて薄く形成できるタグ用アンテナコイルを提供することにある。
本発明の別の目的は、量産性に適したタグ用アンテナコイルを提供することにある。
【０００５】
【課題を解決するための手段】
請求項１に係る発明は、図１及び図２に示すように、電気絶縁フィルム又は電気絶縁シートにより形成された絶縁部材１１と、絶縁部材１１の表面に蛇行して往路部１２ａと復路部１２ｂが交互に形成された一連の導電体１２と、絶縁部材１１の裏面に接着され往路部１２ａと重なることなくそれぞれの復路部１２ｂを絶縁部材１１の裏面から覆う複数の第１磁芯部材１３とを備えたアンテナコイルである。
この請求項１に記載されたアンテナコイルでは、絶縁部材１１の裏面に第１磁芯部材１３を接着するので、導電体１２に流れる電流により生じる磁束は第１磁芯部材１３を通過し、図１の実線矢印で示すようなループを描き、物品１８の表面と平行になり、このアンテナコイルを取り付けた物品の表面が金属であってもその影響を受けずに、このアンテナコイルは確実に作動する。
また、第１磁芯部材１３は往路部１２ａと重なることなく復路部１２ｂを絶縁部材１１の裏面から覆うように絶縁部材１１の裏面に接着されるので、図１の拡大図における破線矢印に示すように、第１磁芯部材１３を通過する磁束は、その端部においてその一部は拡散して往路部１２ａの上方を通過し、隣接する第１磁芯部材１３に再び戻り、往路部１２ａと復路部１２ｂを含む一連の導電体１２がその一部の磁束の周囲に巻回されたアンテナコイルと同一になる。
【０００６】
請求項２に係る発明は、請求項１に係る発明であって、図３及び図４に示すように、絶縁部材１１の表面に複数の第２磁芯部材１４が復路部１２ｂと重なることなくそれぞれの往路部１２ａを覆いかつ端部が隣接する第１磁性部材１３の端部と重なるように接着され、第２磁芯部材１４は第１磁芯部材１３を通過する磁束を往路部１２ａにおいて絶縁部材１１の表面側に導くように構成されたアンテナコイルである。
この請求項２に係るアンテナコイルでは、第１磁芯部材１３を通過する磁束は、図３における実線矢印に示すように、第１及び第２磁芯部材１３，１４を交互に移動しつつそれらの第１及び第２磁芯部材１３，１４を通過する。このため、往路部１２ａと復路部１２ｂは磁束の表及び裏に交互に存在することになり、この往路部１２ａと復路部１２ｂを含む一連の導電体１２がその磁束の周囲に巻回されたアンテナコイルと同一になる。この結果、磁芯部材の外周面に導線を巻回して製作する従来のアンテナコイルと同一の特性を有するアンテナコイル１０を比較的容易に得ることができ、従来の銅線を巻介するアンテナコイルに比較して量産性を向上させることができる。
【０００７】
請求項３に係る発明は、請求項１又は２に係る発明であって、図５及び図６に示すように、導電体１２が所定の間隔をあけて互いに沿うように絶縁部材１１の表面に蛇行して形成された複数本の導電線２１，２２を有し、導電線２１の終端部が隣接する導電線２２の始端部に接続されて一連の導電体１２が構成されたアンテナコイルである。
この請求項３に記載されたアンテナコイルでは、第１及び第２磁芯部材１３，１４を通過する磁束の表及び裏に交互に存在する往路部２１ａ，２２ａと復路部２１ｂ，２２ｂの本数を増加させていわゆる巻き線回数を容易に増加させることができ、この巻き線回数を増加させることによりアンテナコイルの特性を向上させることができる。
【０００８】
請求項４に係る発明は、請求項１ないし３いずれかに係る発明であって、絶縁部材１１の表面全体に接着された導電性箔を所定のパターンでエッチングすることにより、又は絶縁部材１１の表面に導電材料を所定のパターンでスクリーン印刷若しくは蒸着することにより、導電体１２が絶縁部材１１の表面に形成された請アンテナコイルである。
この請求項４に記載されたアンテナコイルでは、導電体１２を絶縁部材１１の表面に形成することが比較的容易になり、アンテナコイルの生産性を更に向上させることができる。
【０００９】
請求項５に係る発明は、請求項１ないし４いずれか記載の発明であって、第１磁芯部材１３及び第２磁芯部材１４のいずれか一方または双方が、軟磁性金属，アモルファス又はフェライトからなる粉末又はフレーク及びプラスチックの複合材、軟磁性金属の板又は箔、アモルファス箔又はその積層材、或いはフェライトであるアンテナコイルである。
この請求項５に記載されたアンテナコイルでは、第１又は第２磁芯部材１３，１４が比較的薄いものになり、アンテナコイルの厚さ方向の大部分を占める磁芯部材１３，１４を薄くすることにより、アンテナコイル全体の厚さを薄くすることができる。
【００１０】
請求項６に係る発明は、請求項１ないし４いずれかに係る発明であって、第１磁芯部材１３及び第２磁芯部材１４のいずれか一方または双方が磁性粉を含むインク又は塗料を絶縁部材１１に塗布乾燥することにより形成された磁性塗膜から構成されたアンテナコイルである。
この請求項６に記載されたアンテナコイルでは、射出成形において成形が困難な０．８ｍｍ以下の厚さの磁芯部材１３，１４を得ることができ、アンテナコイルの厚さを極めて薄く形成することができる。このため、物品に取付けた場合のアンテナコイルの物品から突出量を著しく抑制することができる。
【００１１】
請求項７に係る発明は、請求項１ないし６いずれかに係る発明であって、シート状又は板状の導電部材１６が絶縁部材１１の裏面に第１磁芯部材１３を覆うように接着されたアンテナコイルである。
この請求項７に記載されたアンテナコイルでは、導電体１２と物品と間にその導電部材１６が介在することになるので、その導電部材１６が物品への電波の通過を遮蔽するため、物品の表面が金属により形成されていても、その金属面に生じる渦電流等による損失は発生しない。この結果、アンテナコイルを確実に動作させることができる。
【００１２】
【発明の実施の形態】
次に本発明の第１の実施の形態を図面に基づいて説明する。
図１及び図２に示すように、アンテナコイル１０は、電気絶縁フィルム又は電気絶縁シートにより形成された絶縁部材１１と、絶縁部材１１の表面に導電材料により蛇行するように形成された導電体１２と、絶縁部材１１の裏面に接着され第１磁芯部材１３とを有する。絶縁部材１１は電気絶縁性を有するプラスチック製のフィルム又はシート或いは紙により長方形状に形成されるが、ポリエステルやポリイミド等のプラスチックフィルム又はプラスチックシートにより形成されることが好ましい。導電体１２の形成は、絶縁部材１１の表面に接着された導電性箔を所定のパターンでエッチングすることにより、若しくは所定のパターンで打ち抜かれた導電性箔又は薄板を絶縁部材１１の表面に接着することにより、又は絶縁部材１１の表面にＣｕ，Ａｌ，Ｚｎ等の導電材料を所定のパターンでスクリーン印刷若しくは蒸着することにより形成することができる。
【００１３】
図２に示すように、導電体１２は絶縁部材１１の表面にその幅方向に所定の間隔をあけかつその長手方向に延びる往路部１２ａと復路部１２ｂが交互に形成され、これらの往路部１２ａと復路部１２ｂの両端を交互に接続して上記往路部１２ａと復路部１２ｂを蛇行させる複数の接続部１２ｃとを有する。また絶縁部材１１の表面には一対のリード部１２ｄ，１２ｄが設けられる。これらのリード部１２ｄ，１２ｄの一端は絶縁部材１１の幅方向の両端に位置する往路部１２ａと復路部１２ｂにそれぞれ接続され、他端は絶縁部材１１の幅方向の略中央に互いに近接するように設けられ、タグとして使用する場合におけるＩＣチップ又はコンデンサ１９は、一対のリード線１２ｄ，１２ｄの他端にそれぞれ電気的に接続された状態で、絶縁部材１１の表面に接着される。
【００１４】
一方、第１磁芯部材１３は、往路部１２ａと重なることなく復路部１２ｂを絶縁部材１１の裏面から覆うように絶縁部材１１の裏面に接着される。第１磁芯部材１３としては、軟磁性金属により形成されるか、或いは、軟磁性金属，アモルファス又はフェライトからなる粉末又はフレークとプラスチックとの複合材により形成することができる。また、第１磁芯部材１３としては、Ｆｅ系アモルファス合金（アライドケミカル社製のＭＥＴＧＬＡＳ２６０５Ｓ−２）やＣｏ系アモルファス合金（アライドケミカル社製のＭＥＴＧＬＡＳ２７１２Ａ）等のアモルファス箔又はその積層材により形成されたものであっても良く、方形状に形成されたフェライトであっても良い。
【００１５】
複合材におけるプラスチックとしては加工性の良い熱可塑性のプラスチックを用いたり、或いは耐熱性の良い熱硬化性のプラスチックを用いたりすることができる。また上記軟磁性金属の粉末としては、カーボニル鉄粉末，鉄−パーマロイ等のアトマイズ粉末，還元鉄粉末等が用いられる。一方、軟磁性金属のフレークとしては、上記粉末をボールミル等で微細化して粉末を成形した後に、この粉末を機械的に扁平化して得られたフレークや、鉄系又はコバルト系アモルファス合金の溶湯粒を水冷銅に衝突させて得られたフレークが用いられる。
【００１６】
また第１磁芯部材１３が複合材により形成される場合、その複合材を射出成形又は圧縮成形することにより第１磁芯部材１３を形成することができる。このように形成された第１磁芯部材１３は、脆弱なフェライトにより形成された磁芯部材と比較して、強靱であるため薄くしても割れ難いものになる。また軟磁性金属，アモルファス又はフェライトからなる粉末又はフレークがプラスチックに分散されて、プラスチックにより相互に絶縁されているため、全体としては導電性を有せず、高周波の電波を受けても渦電流は発生しない第１磁芯部材１３が得られる。ここで、極力薄いアンテナコイル１０の厚さ方向の大部分を占めることになる第１磁芯部材１３は極力薄く形成されることが望ましい。具体的にシート状の第１磁芯部材１３を用いる場合には、第１磁芯部材１３を構成するシートの厚さを０．０１〜１ｍｍにすることが好ましく、０．０５〜１ｍｍにすることが更に好ましい。また、このようにシートを薄く形成すれば複数枚のシートを積層して第１磁芯部材１３とすることによりその厚さを調整することもできる。
【００１７】
図１及び図２における第１磁芯部材１３は複合材を方形状に射出成形したシート状のものが用いられ、この第１磁芯部材１３は電気絶縁フィルム１２の裏面に接着される。第１磁芯部材１３の絶縁部材１１への接着は、第１磁芯部材１３及び絶縁部材１１のいずれか一方又は双方に接着剤を塗布し、その後絶縁部材１１に第１磁芯部材１３を押し当てることにより接着する。この場合、第１磁芯部材１３は、往路部１２ａと重なることなく復路部１２ｂを絶縁部材１１の裏面から覆うように絶縁部材１１の裏面に接着される。
【００１８】
この実施の形態では、図１に示すように、シート状又は板状の導電部材１６が絶縁部材１１の裏面に第１磁芯部材１３を覆うように積層接着される。導電部材１６は銅又はアルミニウム等の導電性材料から成り、第１磁芯部材１３が導電性を有する場合には、間に絶縁フィルムを介して積層接着される。導電部材１６の厚さは０．０１ｍｍ〜５ｍｍであることが好ましい。導電部材１６の厚さを０．０１〜５ｍｍにすることにより、導電部材１６と導電体１２との間隔が開き、導電体１２におけるＱ値を向上させてアンテナコイル１０としての性能を向上させることができる。また、導電部材１６の幅１ｃｍ長さ１ｃｍの電気抵抗は５Ω以下であることが好ましい。
【００１９】
このように構成されたアンテナコイル１０は、その厚さが極めて薄く形成できる。またこの薄さのため、このアンテナコイル１０を物品１８に取付けても、アンテナコイル１０が物品１８から殆ど突出することはない。また、絶縁部材１１の裏面に第１磁芯部材１３を接着するので、導電体１２に流れる電流により生じる磁束は第１磁芯部材１３を通過し、図１の実線矢印で示すようなループを描く。また、第１磁芯部材１３は往路部１２ａと重なることなく復路部１２ｂを絶縁部材１１の裏面から覆うように絶縁部材１１の裏面に接着されるので、図１の拡大図における破線矢印に示すように、第１磁芯部材１３を通過する磁束は、その端部においてその一部は拡散して往路部１２ａの上方を通過し、隣接する第１磁芯部材１３に再び戻る。
【００２０】
従って、このタグ用アンテナコイル１０を物品１８の表面に取付けても、その磁束方向は図１の矢印で示すような物品１８の表面と平行になり、物品１８を通過することが少なくなる。このため、物品１８が金属により形成されていても、物品１８に生じる渦電流は抑制されてアンテナコイル１０の共振周波数は上記金属製の物品の影響を受けず、このアンテナコイル１０は確実に作動する。特にこの実施の形態では、導電部材１６を絶縁部材１１の裏面に第１磁芯部材１３を覆うように積層接着したので、第１磁芯部材１３と物品１８と間にその導電部材１６が介在することになる。このため、第１磁芯部材１３を通過してその端部から拡散して往路部１２ａの上方を通過する磁束は増加し、アンテナコイル１０は確実に動作することになる。
【００２１】
なお、上述した実施の形態では、軟磁性金属，複合材、軟磁性金属の板又は箔、アモルファス箔又はその積層材、或いはフェライトからなる第１磁芯部材１３を説明したが、第１磁芯部材１３は図示しないが絶縁性樹脂フィルム又はシートと、この絶縁性樹脂フィルム又はシートの表面に形成された磁性塗膜とを備えるものであっても良い。ここで磁性塗膜を形成する際の絶縁性樹脂フィルム又はシートの厚さは１０〜１００μｍであることが好ましく、更に好ましくは２０〜４０μｍである。この絶縁性樹脂フィルム又はシートとその表面に形成された磁性塗膜からなる磁芯部材では、絶縁性樹脂フィルム又はシートの表面に磁性材料からなる粉末又はフレークを含む塗料を塗布乾燥することにより作られ、射出成形において成形が困難な０．８ｍｍ以下の厚さの第１磁芯部材１３を得ることができ、更に薄いアンテナコイル１０を得ることができる。
【００２２】
次に、図３及び図４に本発明の第２の実施の形態を示す。図面中上述した実施の形態と同一符号は同一部品を示し、繰り返しての説明を省略する。
この実施の形態では、絶縁部材１１の表面に第２磁芯部材１４が復路部１２ｂと重なることなく往路部１２ａを覆いかつ端部が隣接する第１磁性部材１３の端部と重なるように接着される。この実施の形態における第２磁芯部材１４は、磁性材料からなる粉末又はフレークを含む塗料を塗布乾燥することにより形成された磁性塗膜から形成される。即ち、磁性材料からなる粉末又はフレークを含む塗料が復路部１２ｂと重なることなく往路部１２ａを覆うように絶縁部材１１の表面に塗布され、その後乾燥することにより第２磁芯部材１４を構成する磁性塗膜が形成される。
【００２３】
ここで塗料に含ませる磁性材料の粉末としては、カーボニル鉄粉末，鉄−パーマロイ等のアトマイズ粉末，還元鉄粉末等が用いられる。一方、磁性材料のフレークとしては、上記粉末をボールミル等で微細化して粉末を成形した後に、この粉末を機械的に扁平化して得られたフレークや、鉄系又はコバルト系アモルファス合金の溶湯粒を水冷銅に衝突させて得られたフレークが用いられる。また形成された磁性塗膜の厚さは１０〜８００μｍが好ましく、更に好ましくは３０〜３００μｍである。なお、塗料を一度塗布しただけでは所定の厚さが得られない場合には、繰り返し同一の塗料を塗布乾燥することにより所望の厚さの塗膜を得ることができる。この磁性塗膜からなる第２磁芯部材１４は、塗料を塗布乾燥させるだけの簡単な作業で比較的薄い第２磁芯部材１４を得ることが可能になる。
【００２４】
このように構成されたアンテナコイル１０は、第２磁芯部材１４が磁性塗膜から形成されるので、射出成形において成形が困難な０．８ｍｍ以下の厚さの第２磁芯部材１４を得ることが可能になり、その厚さを薄くすることができる。また、往路部１２ａを覆いかつ端部が隣接する第１磁性部材１３の端部と重なるように第２磁芯部材１４を絶縁部材１１の表面に接着するので、第１磁芯部材１３を通過する磁束は、図３における実線矢印に示すように、第１磁芯部材１３の端部において第２磁芯部材１４に移行して往路部１２ａの上方を通過し、第２磁芯部材１４の端部から隣接する第１磁芯部材１３の端部に再び移行する。このため、第２磁芯部材１４は第１磁芯部材１３を通過する磁束を往路部１２ａにおいて絶縁部材１１の表面側に導き、磁束は第１及び第２磁芯部材１３，１４を交互に移動しつつそれらの第１及び第２磁芯部材１３，１４を通過する。このため、往路部１２ａと復路部１２ｂは磁束の表及び裏に交互に存在することになり、この往路部１２ａと復路部１２ｂを含む一連の導電体１２がその磁束の周囲に巻回されたアンテナコイルと同一になる。このため、磁芯部材の外周面に導線を巻回して第１導体を製作する従来のアンテナコイルと同一の特性を有するアンテナコイル１０を比較的容易に得ることができ、従来の銅線を巻介するアンテナコイルに比較して量産性を向上させることができる。
【００２５】
次に、図５及び図６に本発明の第３の実施の形態を示す。図面中上述した実施の形態と同一符号は同一部品を示し、繰り返しての説明を省略する。
この実施の形態では、導電体１２が２本の導電線２１，２２を有し、この２本の導電線２１，２２は所定の間隔をあけて互いに沿うように絶縁部材１１の表面にそれぞれ蛇行して形成される。２本の導電線２１，２２には往路部２１ａ，２２ａと復路部２１ｂ，２２ｂがそれぞれ交互に形成され、それぞれの往路部２１ａ，２２ａと復路部２１ｂ，２２ｂが複数の接続部２１ｃ，２２ｃにより交互に接続される。また２本の導電線２１，２２の両端にはリード部２１ｄ，２２ｄがそれぞれ設けられ、一方の導電線２１の終端部におけるリード部２１ｄが隣接する他方の導電線１１の始端部におけるリード部２２ｄに接続されて一連の導電体１２が構成される。
【００２６】
そして、往路部２１ａ，２２ａと重なることなく復路部２１ｂ，２２ｂを絶縁部材１１の裏面から覆うように第１磁芯部材１３が絶縁部材１１の裏面に接着され、絶縁部材１１の表面に第２磁芯部材１４が復路部２１ｂ，２２ｂと重なることなく往路部２１ａ，２２ａを覆いかつ端部が隣接する第１磁性部材１３の端部と重なるように接着される。
このように構成されたアンテナコイル１０では、導電体１２を２本の導電線２１，２２により構成するので、第１及び第２磁芯部材１３，１４を通過する磁束の表及び裏に交互に存在する往路部２１ａ，２２ａと復路部２１ｂ，２２ｂの本数は単一の導電線から導電体が構成される場合に比較して増加する。このため、いわゆる巻き線回数が増加することになり、この巻き線回数を増加させることによりアンテナコイルの特性を向上させることができる。
【００２７】
なお、上述した第３の実施の形態では、２本の導電線２１，２２から構成される導電体１２を説明したが、導電体１２は図７に示すように３本の導電線３１，３２，３３から構成されるものであっても良く、図示しないが４本、５本、６本、７本、又は９本以上の導電線から構成しても良い。導電線の数を増加させると、いわゆる巻き線回数が増加することになり、この巻き線回数を増加させることによりアンテナコイルの特性を更に向上させることができる。
また、上述した実施の形態では、複合材を射出成形することにより得られた第１磁芯部材１３と磁性塗膜からなる第２磁芯部材１４を説明したが、第１磁芯部材を磁性塗膜から構成しても良く、第２磁芯部材を軟磁性金属，アモルファス又はフェライトからなる粉末又はフレーク及びプラスチックの複合材、軟磁性金属の板又は箔、アモルファス箔又はその積層材、或いはフェライトにより構成しても良い。
【００２８】
【実施例】
次に本発明の実施例を比較例とともに詳しく説明する。
＜実施例１＞
図１及び図２に示すように電気絶縁フィルムからなる絶縁部材１１の表面に導電体１２を形成した。電気絶縁フィルムとしては、厚さ５０μｍであって縦及び横が６５ｍｍ×５５ｍｍのポリイミドフィルムを用いた。このポリイミドフィルムの一方の主面に厚さ３５μｍの銅箔を積層接着し、この銅箔をエッチングすることによりポリイミドフィルムの一方の表面に蛇行して、長さがそれぞれ４０ｍｍの往路部１２ａと復路部１２ｂが１０ｍｍの隙間を開けて交互に３本形成された一連の導電体１２を形成した。この導電体１２は０．８ｍｍの幅に形成した。
【００２９】
その後、導電体１２が設けられた電気絶縁フィルム１２の裏面に、厚さが１ｍｍであって縦及び横が４０ｍｍ×２０ｍｍの第１磁芯部材１３を接着した。第１磁芯部材１３としては、カーボニル鉄粉をナイロン樹脂に９２重量％含ませた複合材を射出成形したものを使用した。第１磁芯部材１３の接着は、第１磁芯部材１３が往路部１２ａと重なることなく復路部１２ｂを絶縁部材１１の裏面から覆うように行った。
そして厚さが０．１ｍｍであって縦及び横が７０ｍｍ×６０ｍｍのアルミ板からなる導電部材１６を、絶縁部材１１の裏面に第１磁芯部材１３を覆うように接着した。このようにして第１磁芯部材１３のみを有するアンテナコイルを実施例１とした。
【００３０】
＜実施例２＞
実施例１と同一の第１磁芯部材１３のみを有するアンテナコイルを得た。そして実施例１と同一の複合材により実施例１における第１磁芯部材と同形同大の第２磁芯部材１４を準備した。この第２磁芯部材１４を復路部１２ｂと重なることなく往路部１２ａを覆いかつ端部が隣接する第１磁性部材１３の端部と重なるように絶縁部材１１の表面に接着して図３及び図４に示すアンテナコイルを得た。このように第１磁芯部材１３及び第２磁芯部材１４の双方を有するアンテナコイルを実施例２とした。
【００３１】
＜比較例１＞
図９に示すようにベース板１としての単一の電気絶縁フィルムにコイル本体２を形成した。電気絶縁フィルム１としては、厚さ５０μｍであって縦及び横がそれぞれ５０ｍｍのポリイミドフィルムを用いた。このポリイミドフィルム１の表面に厚さ３５μｍの銅箔を積層接着し、この銅箔をエッチングすることにより導体を形成して、ポリイミドフィルムの一方の主面にその導体が４回渦巻き状に巻回されたコイル本体２を形成した。導体は０．８ｍｍの幅に形成され、この導体により形成されるコイル本体２の外形は４５ｍｍ×４５ｍｍであり、このコイル本体２により包囲される中央部は３７ｍｍ×３７ｍｍの方形状になるように形成した。そして厚さが０．１ｍｍであって縦及び横が７０ｍｍ×６０ｍｍのアルミ板からなる図示しない導電部材を、電気絶縁フィルムからなるベース板１の裏面に接着した。この電気絶縁フィルムからなるベース板１に渦巻き状のコイル本体２が形成されたアンテナコイルを比較例１とした。
【００３２】
＜比較試験＞
物品として、１００ｍｍ×１００ｍｍであって厚さが０．１６ｍｍのアクリル板と、そのアクリル板と同形同大のアルミニウム板及び軟鋼板をそれぞれ準備した。これらのアクリル板、アルミニウム板及び軟鋼板の表面に上述した実施例１及び２並びに比較例１におけるアンテナコイルをそれぞれ配置した。アンテナコイルの配置に際しては、導電部材がそれらの物品に直接接触するように配置した。そして、それらのアンテナコイルの導電体１２の両端部（図２のＸ及びＹ）に、コイル特性を測定する測定器（HEWLETT PACKARD社製４３９５）の測定用ターミナルを接続させ、その測定器により所定の周波数に対するコイル本体のＬ値並びにＱ値をそれぞれ測定した。
また、比較例１及び実施例１のアンテナコイルにそれぞれコンデンサ１６を接続して８．２ＭＨｚで作動するＥＡＳタグを得た。このタグを上述したアクリル板、アルミニウム板及び軟鋼板の表面にそれぞれ配置した場合の動作の有無を確認した。これらの結果を表１にそれぞれ示す。
【００３３】
【表１】

【００３４】
表１から明らかなように、実施例１及び実施例２ではアクリル板、アルミニウム板及び軟鋼板上のいずれでもＬ値はほとんど変らず、アルミニウム板及び軟鋼板上の場合もアクリル板の場合に比較してＱ値の低下は少ない。しかし比較例１ではアクリル板上に比較しアルミニウム板上ではＬ値が著しく変化する。また軟鋼板上の場合はＱ値が著しく低下する。これは実施例１及び実施例２ではコイルから発生する磁束の方向が板の面に平行になっているのに対して、比較例では磁束の方向が板の面に垂直であって、導電部材を接着していても磁束の大部分が板に到達してしまうことに起因するものと考えられる。また、実施例１及び実施例２のアンテナコイルにＩＣチップを接続したタグは、アクリル板、アルミニウム板及び軟鋼板のいずれの表面に配置しても動作するのに対して、比較例１のアンテナコイルにＩＣチップを接続したタグは、アクリル板の表面に配置した場合にのみ動作し、アルミニウム板及び軟鋼板の表面に配置した場合には動作しなかった。これはアルミニウム板の場合はＬ値が変化し、共振周波数が変化したことと、エネルギーが鉄板に吸収され損失となったためと考えられる。
【００３５】
【発明の効果】
以上述べたように、本発明によれば、絶縁部材と、絶縁部材の表面に蛇行して往路部と復路部が交互に形成された一連の導電体と、絶縁部材の裏面に接着された第１磁芯部材とを備えたので、導電体に流れる電流により生じる磁束は第１磁芯部材を通過してアンテナコイルが取付けられる物品の表面と平行になる。また、第１磁芯部材は往路部と重なることなく復路部を絶縁部材の裏面から覆うように絶縁部材の裏面に接着されるので、第１磁芯部材を通過する磁束は、その端部においてその一部は拡散して往路部の上方を通過し、隣接する第１磁芯部材に再び戻り、その物品表面が金属であってもその影響を受けずに確実に作動する。
【００３６】
また、復路部と重なることなく往路部を覆いかつ端部が隣接する第１磁性部材の端部と重なるように第２磁芯部材を絶縁部材の表面に接着すれば、磁束が第１及び第２磁芯部材を交互に移動しつつそれらの第１及び第２磁芯部材を通過する。このため、往路部と復路部は磁束の表及び裏に交互に存在することになり、この往路部と復路部を含む一連の導電体がその磁束の周囲に巻回されたアンテナコイルと同一になり、磁芯部材の外周面に導線を巻回して製作する従来のアンテナコイルと同一の特性を有するアンテナコイルを比較的容易に得ることができ、その量産性を向上させることができる。更に、所定の間隔をあけて互いに沿うように絶縁部材の表面に蛇行して形成された複数本の導電線により一連の導電体を形成すれば、磁束の表及び裏に交互に存在する往路部と復路部の本数を増加させていわゆる巻き線回数を容易に増加させることができ、この巻き線回数を増加させることによりアンテナコイルの特性を向上させることができる。
【００３７】
更に、導電体をエッチング若しくは打ち抜き、又はスクリーン印刷若しくは蒸着することにより形成すれば、絶縁部材への導電体の形成が比較的容易になり、第１又は第２磁芯部材が、軟磁性金属，アモルファス又はフェライトからなる粉末又はフレーク及びプラスチックの複合材、軟磁性金属の板又は箔、アモルファス箔又はその積層材、或いはフェライトであれば、磁芯部材が比較的薄いものになり、アンテナコイル全体の厚さを薄くすることができる。特に磁性塗膜を磁芯部材とすることにより、磁芯部材を更に薄くすることができ、射出成形において成形が困難な０．８ｍｍ以下の厚さの磁芯部材により更に薄いアンテナコイルを得ることが可能になる。
【図面の簡単な説明】
【図１】本発明第１実施形態のアンテナコイルを示す図２のＡ−Ａ線断面図。
【図２】そのアンテナコイルの平面図。
【図３】本発明第２実施形態のアンテナコイルを示す図１に対応する断面図。
【図４】そのアンテナコイルの平面図。
【図５】本発明第３実施形態のアンテナコイルを示す図１に対応する断面図。
【図６】そのアンテナコイルの平面図。
【図７】３本の導電線からなる導電体を有するアンテナコイルの平面図。
【図８】磁芯部材に螺旋状に巻回された導体を有する従来のアンテナコイルを示す斜視図。
【図９】渦巻き状のコイル本体からなる従来のアンテナコイルを示す斜視図。
【符号の説明】
１１絶縁部材
１２導電体
１２ａ，２１ａ，２２ａ往路部
１２ｂ，２１ｂ，２２ｂ復路部
１３第１磁芯部材
１４第２磁芯部材
１６導電部材
２１，２２導電線[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an antenna coil used for an identification tag using RFID (Radio Frequency Identification) technology or EAS (Electronic Article Sureillannce) technology.
[0002]
[Prior art]
Conventionally, an identification tag in which an IC chip storing information in an antenna coil or a resonance capacitor is electrically connected is known as a tag using RFID technology or EAS technology. These identification tags activate the tag by transmitting a radio wave of a predetermined frequency from the transmission / reception antenna of the interrogator to the antenna coil, and read information stored in the IC chip in response to a read command by radio wave data communication. Or an article configured to identify or monitor the article depending on whether or not it resonates with a radio wave of a specific frequency.
As a conventional antenna coil used for these identification tags, a conductor wire whose surface is covered with an insulating layer is wound in a substantially square spiral shape and attached to a base plate, or FIG. As shown in the figure, a conductive layer such as an aluminum foil or a copper foil laminated on a base plate 1 is removed from an unnecessary portion by an etching method or a punching method to form a substantially square spiral coil body 2. .
[0003]
However, in the antenna coil shown in FIG. 9, the magnetic flux is generated in the direction vertically passing through the base plate 1 as shown by the arrows in the figure, and when the antenna coil is brought into close contact with a metal article, it is transmitted toward the antenna coil. The transmitted radio wave penetrates the base plate 1 and further penetrates the metal article. For this reason, an eddy current is generated in the metal portion by the penetrating magnetic flux, and the eddy current affects the antenna coil so that the antenna coil does not operate normally. Further, even if it operates, there is a problem that the loss increases and the working distance of the antenna coil is remarkably shortened.
In order to eliminate this point, an antenna coil having a magnetic core member 6 formed in a plate shape or a columnar shape as shown in FIG. 8 and a conductor 7 wound spirally around the magnetic core member 6 It has been known. In the antenna coil shown in FIG. 8, since the magnetic flux is generated in the axial direction of the magnetic core member 6 as shown by the arrow in the figure, even if this antenna coil is attached to a metal article, it is transmitted toward the antenna coil. It is expected that the radio wave does not penetrate through the metal article and the antenna coil operates normally.
[0004]
[Problems to be solved by the invention]
However, since the antenna coil shown in FIG. 8 is manufactured by winding the conductor 7 around the outer peripheral surface of the magnetic core member 6, the winding work is relatively complicated and lacks mass productivity. Further, since the conductor 7 is wound around the outer peripheral surface of the magnetic core member 6, the entire antenna coil becomes relatively thick. When the antenna coil is attached to the surface of the article, the antenna coil protrudes relatively large from the article. There was a problem to do.
An object of the present invention is to provide a tag antenna coil that can be reliably operated even when it is brought into close contact with a metal article and can be formed extremely thin.
Another object of the present invention is to provide a tag antenna coil suitable for mass productivity.
[0005]
[Means for Solving the Problems]
As shown in FIGS. 1 and 2, the invention according to claim 1 includes an insulating member 11 formed of an electric insulating film or an electric insulating sheet, and a forward path portion 12a and a return path portion 12b meandering on the surface of the insulating member 11. Are bonded to the back surface of the insulating member 11 without overlapping the forward path portion 12a. each The return path portion 12b is covered from the back surface of the insulating member 11. plural The antenna coil includes a first magnetic core member 13.
In the antenna coil according to the first aspect, since the first magnetic core member 13 is bonded to the back surface of the insulating member 11, the magnetic flux generated by the current flowing through the conductor 12 passes through the first magnetic core member 13, and FIG. A loop as indicated by a solid line arrow 1 is drawn, parallel to the surface of the article 18, and even if the surface of the article to which the antenna coil is attached is a metal, the antenna coil operates reliably. To do.
The first magnetic core member 13 is bonded to the back surface of the insulating member 11 so as to cover the return path portion 12b from the back surface of the insulating member 11 without overlapping the forward path portion 12a. As described above, a part of the magnetic flux passing through the first magnetic core member 13 diffuses at the end thereof, passes above the forward path portion 12a, returns to the adjacent first magnetic core member 13, and returns to the forward path portion 12a. The series of conductors 12 including the return path portion 12b is the same as the antenna coil wound around a part of the magnetic flux.
[0006]
The invention according to claim 2 is the invention according to claim 1, wherein, as shown in FIG. 3 and FIG. plural The second magnetic core member 14 does not overlap the return path portion 12b. each The second magnetic core member 14 covers the forward path portion 12a and is bonded so that the end portion thereof overlaps the end portion of the adjacent first magnetic member 13, and the second magnetic core member 14 insulates the magnetic flux passing through the first magnetic core member 13 in the forward path portion 12a. 11 is an antenna coil configured to be led to the surface side of the antenna 11.
In the antenna coil according to the second aspect, the magnetic flux passing through the first magnetic core member 13 moves alternately between the first and second

magnetic core members

13 and 14 as shown by solid arrows in FIG. The first and second

magnetic core members

13 and 14 pass through. For this reason, the forward path portion 12a and the return path portion 12b are alternately present on the front and back of the magnetic flux, and a series of conductors 12 including the forward path portion 12a and the return path portion 12b are wound around the magnetic flux. Same as antenna coil. As a result, it is possible to relatively easily obtain the antenna coil 10 having the same characteristics as the conventional antenna coil manufactured by winding the conductive wire around the outer peripheral surface of the magnetic core member. In comparison, mass productivity can be improved.
[0007]
The invention according to claim 3 is the invention according to claim 1 or 2, and as shown in FIGS. 5 and 6, the conductors 12 are formed on the surface of the insulating member 11 so as to follow each other at a predetermined interval. An antenna coil having a plurality of

conductive wires

21 and 22 formed in a meandering manner and having a series of conductors 12 formed by connecting a terminal portion of a conductive wire 21 to a starting end portion of an adjacent conductive wire 22. .
In the antenna coil according to the third aspect, the number of the

forward path portions

21a and 22a and the

return path portions

21b and 22b that alternately exist on the front and back sides of the magnetic flux passing through the first and second

magnetic core members

13 and 14 is set. By increasing the number of windings, the number of windings can be easily increased. By increasing the number of windings, the characteristics of the antenna coil can be improved.
[0008]
The invention according to claim 4 is the invention according to any one of claims 1 to 3, wherein the conductive foil bonded to the entire surface of the insulating member 11 is etched in a predetermined pattern, or the insulating member 11 The conductor antenna 12 is an antenna coil formed on the surface of the insulating member 11 by screen printing or vapor-depositing a conductive material on the surface in a predetermined pattern.
In the antenna coil according to the fourth aspect, it becomes relatively easy to form the conductor 12 on the surface of the insulating member 11, and the productivity of the antenna coil can be further improved.
[0009]
The invention according to claim 5 is the invention according to any one of claims 1 to 4, wherein one or both of the first magnetic core member 13 and the second magnetic core member 14 are soft magnetic metal, amorphous or ferrite. A composite material of powder or flakes and plastic, a soft magnetic metal plate or foil, an amorphous foil or a laminate thereof, or an antenna coil made of ferrite.
In the antenna coil described in claim 5, the first or second

magnetic core members

13, 14 are relatively thin, and the

magnetic core members

13, 14 occupying most of the antenna coil in the thickness direction are thinned. By doing so, the thickness of the whole antenna coil can be reduced.
[0010]
An invention according to a sixth aspect is the invention according to any one of the first to fourth aspects, wherein one or both of the first magnetic core member 13 and the second magnetic core member 14 includes an ink or a paint containing magnetic powder. It is an antenna coil composed of a magnetic coating film formed by applying and drying the insulating member 11.
In the antenna coil according to the sixth aspect, the

magnetic core members

13 and 14 having a thickness of 0.8 mm or less, which are difficult to be formed by injection molding, can be obtained, and the thickness of the antenna coil is extremely thin. Can do. For this reason, the protrusion amount from the article of the antenna coil when attached to the article can be remarkably suppressed.
[0011]
The invention according to claim 7 is the invention according to any one of claims 1 to 6, wherein the sheet-like or plate-like conductive member 16 is bonded to the back surface of the insulating member 11 so as to cover the first magnetic core member 13. Antenna coil.
In the antenna coil described in claim 7, since the conductive member 16 is interposed between the conductor 12 and the article, the conductive member 16 shields the passage of radio waves to the article. Even if the surface is formed of metal, loss due to eddy currents or the like generated on the metal surface does not occur. As a result, the antenna coil can be reliably operated.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Next, a first embodiment of the present invention will be described with reference to the drawings.
As shown in FIGS. 1 and 2, the antenna coil 10 includes an insulating member 11 formed of an electric insulating film or an electric insulating sheet, and a conductor 12 formed to meander on the surface of the insulating member 11 with a conductive material. And a first magnetic core member 13 bonded to the back surface of the insulating member 11. The insulating member 11 is formed in a rectangular shape by a plastic film or sheet having electrical insulating properties or paper, but is preferably formed by a plastic film or plastic sheet such as polyester or polyimide. The conductor 12 is formed by etching the conductive foil bonded to the surface of the insulating member 11 with a predetermined pattern, or bonding the conductive foil or thin plate punched out with the predetermined pattern to the surface of the insulating member 11. By doing so, a conductive material such as Cu, Al, Zn or the like can be formed on the surface of the insulating member 11 by screen printing or vapor deposition in a predetermined pattern.
[0013]
As shown in FIG. 2, in the conductor 12, the forward path portions 12a and the return path portions 12b are formed alternately on the surface of the insulating member 11 with a predetermined interval in the width direction and extending in the longitudinal direction thereof. And a plurality of connection portions 12c that meander the forward path portion 12a and the return path portion 12b by alternately connecting both ends of the return path portion 12b. A pair of

lead portions

12 d and 12 d are provided on the surface of the insulating member 11. One end of each of the

lead portions

12d and 12d is connected to the forward path portion 12a and the backward path portion 12b located at both ends in the width direction of the insulating member 11, and the other end is close to the approximate center in the width direction of the insulating member 11. When used as a tag, the IC chip or capacitor 19 is bonded to the surface of the insulating member 11 in a state where it is electrically connected to the other ends of the pair of

lead wires

12d and 12d.
[0014]
On the other hand, the first magnetic core member 13 is bonded to the back surface of the insulating member 11 so as to cover the return path portion 12b from the back surface of the insulating member 11 without overlapping the forward path portion 12a. The first magnetic core member 13 can be formed of a soft magnetic metal or a composite of powder or flakes made of soft magnetic metal, amorphous or ferrite, and plastic. The first magnetic core member 13 is formed of an amorphous foil such as an Fe-based amorphous alloy (METGLAS 2605S-2 manufactured by Allied Chemical) or a Co-based amorphous alloy (METGLAS 2712A manufactured by Allied Chemical) or a laminated material thereof. May be a ferrite formed in a square shape.
[0015]
As the plastic in the composite material, a thermoplastic plastic having good processability can be used, or a thermosetting plastic having good heat resistance can be used. Examples of the soft magnetic metal powder include carbonyl iron powder, atomized powder such as iron-permalloy, and reduced iron powder. On the other hand, as flakes of soft magnetic metal, the above powder is refined with a ball mill or the like to form a powder, and then the powder is mechanically flattened, or a molten particle of iron-based or cobalt-based amorphous alloy Flakes obtained by impinging on water-cooled copper are used.
[0016]
When the first magnetic core member 13 is formed of a composite material, the first magnetic core member 13 can be formed by injection molding or compression molding the composite material. The first magnetic core member 13 formed in this way is tougher than a magnetic core member formed of fragile ferrite, so it is difficult to break even if it is thin. Also, since powders or flakes made of soft magnetic metal, amorphous or ferrite are dispersed in plastic and insulated from each other by plastic, they do not have electrical conductivity as a whole, and eddy currents are not affected by high-frequency radio waves. The 1st magnetic core member 13 which does not generate | occur | produce is obtained. Here, it is desirable that the first magnetic core member 13 that occupies most of the antenna coil 10 in the thickness direction as thin as possible is formed as thin as possible. Specifically, when the sheet-like first magnetic core member 13 is used, the thickness of the sheet constituting the first magnetic core member 13 is preferably 0.01 to 1 mm, and is preferably 0.05 to 1 mm. More preferably. In addition, if the sheet is formed thin in this way, the thickness can be adjusted by stacking a plurality of sheets to form the first magnetic core member 13.
[0017]
The first magnetic core member 13 in FIG. 1 and FIG. 2 is a sheet-like member in which a composite material is injection-molded into a square shape, and the first magnetic core member 13 is bonded to the back surface of the electrical insulating film 12. The first magnetic core member 13 is bonded to the insulating member 11 by applying an adhesive to one or both of the first magnetic core member 13 and the insulating member 11, and then attaching the first magnetic core member 13 to the insulating member 11. Adhere by pressing. In this case, the first magnetic core member 13 is bonded to the back surface of the insulating member 11 so as to cover the return path portion 12b from the back surface of the insulating member 11 without overlapping the forward path portion 12a.
[0018]
In this embodiment, as shown in FIG. 1, a sheet-like or plate-like conductive member 16 is laminated and bonded to the back surface of the insulating member 11 so as to cover the first magnetic core member 13. The conductive member 16 is made of a conductive material such as copper or aluminum. When the first magnetic core member 13 has conductivity, the conductive member 16 is laminated and bonded via an insulating film therebetween. The thickness of the conductive member 16 is preferably 0.01 mm to 5 mm. By setting the thickness of the conductive member 16 to 0.01 to 5 mm, the gap between the conductive member 16 and the conductor 12 is increased, and the Q value of the conductor 12 is improved to improve the performance as the antenna coil 10. Can do. The electrical resistance of the conductive member 16 having a width of 1 cm and a length of 1 cm is preferably 5Ω or less.
[0019]
The antenna coil 10 thus configured can be formed to be extremely thin. Further, due to this thinness, even when the antenna coil 10 is attached to the article 18, the antenna coil 10 hardly protrudes from the article 18. Further, since the first magnetic core member 13 is bonded to the back surface of the insulating member 11, the magnetic flux generated by the current flowing through the conductor 12 passes through the first magnetic core member 13 and loops as shown by the solid line arrow in FIG. Draw. The first magnetic core member 13 is bonded to the back surface of the insulating member 11 so as to cover the return path portion 12b from the back surface of the insulating member 11 without overlapping the forward path portion 12a. Thus, a part of the magnetic flux passing through the first magnetic core member 13 is diffused at the end portion, passes above the forward path portion 12a, and returns to the adjacent first magnetic core member 13 again.
[0020]
Therefore, even if the tag antenna coil 10 is attached to the surface of the article 18, the direction of the magnetic flux is parallel to the surface of the article 18 as shown by the arrow in FIG. For this reason, even if the article 18 is made of metal, the eddy current generated in the article 18 is suppressed, and the resonance frequency of the antenna coil 10 is not affected by the metal article, so that the antenna coil 10 operates reliably. To do. Particularly in this embodiment, since the conductive member 16 is laminated and bonded to the back surface of the insulating member 11 so as to cover the first magnetic core member 13, the conductive member 16 is interposed between the first magnetic core member 13 and the article 18. Will do. For this reason, the magnetic flux passing through the first magnetic core member 13 and diffusing from the end portion thereof and passing over the forward path portion 12a increases, and the antenna coil 10 operates reliably.
[0021]
In the above-described embodiment, the first magnetic core member 13 made of soft magnetic metal, composite material, soft magnetic metal plate or foil, amorphous foil or laminated material thereof, or ferrite has been described. Although not shown, the member 13 may include an insulating resin film or sheet and a magnetic coating film formed on the surface of the insulating resin film or sheet. Here, the thickness of the insulating resin film or sheet when forming the magnetic coating film is preferably 10 to 100 μm, and more preferably 20 to 40 μm. In the magnetic core member comprising the insulating resin film or sheet and the magnetic coating film formed on the surface thereof, the surface of the insulating resin film or sheet is prepared by applying and drying a coating material containing powder or flakes made of a magnetic material. Thus, it is possible to obtain the first magnetic core member 13 having a thickness of 0.8 mm or less, which is difficult to be molded by injection molding, and to obtain the thinner antenna coil 10.
[0022]
Next, FIGS. 3 and 4 show a second embodiment of the present invention. In the drawings, the same reference numerals as those in the above-described embodiment denote the same parts, and repeated description will be omitted.
In this embodiment, the second magnetic core member 14 is bonded to the surface of the insulating member 11 so as to cover the forward path portion 12a without overlapping the return path portion 12b and to overlap the end portion of the adjacent first magnetic member 13. Is done. The second magnetic core member 14 in this embodiment is formed from a magnetic coating film formed by applying and drying a coating material containing powder or flakes made of a magnetic material. That is, the coating material containing powder or flakes made of a magnetic material is applied to the surface of the insulating member 11 so as to cover the forward path portion 12a without overlapping the backward path portion 12b, and then dried to constitute the second magnetic core member 14. A magnetic coating is formed.
[0023]
Here, as the powder of the magnetic material included in the paint, carbonyl iron powder, atomized powder such as iron-permalloy, reduced iron powder, and the like are used. On the other hand, as flakes of magnetic material, flakes obtained by refining the above powder with a ball mill or the like and molding the powder, and then mechanically flattening this powder, or molten particles of iron-based or cobalt-based amorphous alloy are used. Flakes obtained by colliding with water-cooled copper are used. Moreover, 10-800 micrometers is preferable and, as for the thickness of the formed magnetic coating film, More preferably, it is 30-300 micrometers. In addition, when a predetermined thickness cannot be obtained only by applying a coating material once, a coating film having a desired thickness can be obtained by repeatedly applying and drying the same coating material. The second magnetic core member 14 made of this magnetic coating film can obtain the relatively thin second magnetic core member 14 by a simple operation of simply applying and drying the paint.
[0024]
In the antenna coil 10 configured in this manner, since the second magnetic core member 14 is formed from a magnetic coating film, the second magnetic core member 14 having a thickness of 0.8 mm or less that is difficult to be molded by injection molding is obtained. And the thickness can be reduced. Further, since the second magnetic core member 14 is bonded to the surface of the insulating member 11 so as to cover the forward path portion 12a and the end portion thereof overlaps the end portion of the adjacent first magnetic member 13, the first magnetic core member 13 is passed. The magnetic flux to be transferred to the second magnetic core member 14 at the end of the first magnetic core member 13 and passes above the forward path portion 12a as shown by the solid line arrow in FIG. The transition is made again from the end to the end of the adjacent first magnetic core member 13. For this reason, the second magnetic core member 14 guides the magnetic flux passing through the first magnetic core member 13 to the surface side of the insulating member 11 in the forward path portion 12a, and the magnetic flux alternates between the first and second

magnetic core members

13 and 14. Passing through the first and second

magnetic core members

13 and 14 while moving. For this reason, the forward path portion 12a and the return path portion 12b are alternately present on the front and back sides of the magnetic flux, and a series of conductors 12 including the forward path portion 12a and the return path portion 12b are wound around the magnetic flux. Same as antenna coil. For this reason, it is possible to obtain the antenna coil 10 having the same characteristics as those of the conventional antenna coil for winding the conductive wire around the outer peripheral surface of the magnetic core member and manufacturing the first conductor. The mass productivity can be improved as compared with the antenna coil interposed.
[0025]
Next, FIGS. 5 and 6 show a third embodiment of the present invention. In the drawings, the same reference numerals as those of the above-described embodiment denote the same parts, and repeated description will be omitted.
In this embodiment, the conductor 12 has two

conductive lines

21 and 22, and the two

conductive lines

21 and 22 meander on the surface of the insulating member 11 so as to be along each other at a predetermined interval. Formed.

Outward path portions

21a and 22a and return

path portions

21b and 22b are alternately formed in the two

conductive wires

21 and 22, respectively, and each of the

forward path portions

21a and 22a and the

return path portions

21b and 22b are formed by a plurality of

connection portions

21c and 22c. Connected alternately. Lead

portions

21 d and 22 d are provided at both ends of the two

conductive wires

21 and 22, respectively, and the lead portion 21 d at the end portion of one conductive wire 21 is the lead portion 22 d at the start end portion of the other conductive wire 11 adjacent thereto. A series of conductors 12 is configured.
[0026]
Then, the first magnetic core member 13 is bonded to the back surface of the insulating member 11 so as to cover the

return path portions

21b and 22b from the back surface of the insulating member 11 without overlapping with the

forward path portions

21a and 22a. The magnetic core member 14 is bonded so as to cover the

forward path portions

21a and 22a without overlapping the

return path portions

21b and 22b and to overlap the end portion of the adjacent first magnetic member 13.
In the antenna coil 10 configured as described above, the conductor 12 is constituted by the two

conductive wires

21 and 22, so that the magnetic flux passing through the first and second

magnetic core members

13 and 14 is alternately arranged on the front and back sides. The number of the existing forward

path portions

21a and 22a and the

backward path portions

21b and 22b increases as compared with the case where the conductor is constituted by a single conductive line. For this reason, the number of windings increases, and the characteristics of the antenna coil can be improved by increasing the number of windings.
[0027]
In the third embodiment described above, the conductor 12 composed of the two

conductive lines

21 and 22 has been described. However, the conductor 12 includes three conductive lines 31 and 32 as shown in FIG. , 33, or although not shown, it may be composed of 4, 5, 6, 7, or 9 or more conductive wires. When the number of conductive wires is increased, the so-called number of windings increases, and the characteristics of the antenna coil can be further improved by increasing the number of windings.
In the above-described embodiment, the first magnetic core member 13 obtained by injection molding of the composite material and the second magnetic core member 14 made of a magnetic coating film have been described. However, the first magnetic core member is made magnetic. The second magnetic core member may be composed of a coating film, and the second magnetic core member is a composite material of powder or flakes made of soft magnetic metal, amorphous or ferrite, and plastic, a plate or foil of soft magnetic metal, an amorphous foil or a laminate thereof, or ferrite You may comprise by.
[0028]
【Example】
Next, examples of the present invention will be described in detail together with comparative examples.
<Example 1>
As shown in FIG.1 and FIG.2, the conductor 12 was formed in the surface of the insulating member 11 which consists of an electrical insulating film. As the electrical insulating film, a polyimide film having a thickness of 50 μm and a length and width of 65 mm × 55 mm was used. A copper foil having a thickness of 35 μm is laminated and bonded to one main surface of the polyimide film, and the copper foil is etched to meander to one surface of the polyimide film, and the forward path portion 12a and the return path each have a length of 40 mm. A series of conductors 12 in which three portions 12b were alternately formed with a gap of 10 mm were formed. This conductor 12 was formed to a width of 0.8 mm.
[0029]
Thereafter, a first magnetic core member 13 having a thickness of 1 mm and a length and width of 40 mm × 20 mm was bonded to the back surface of the electrical insulating film 12 provided with the conductor 12. As the first magnetic core member 13, a material obtained by injection-molding a composite material containing 92% by weight of carbonyl iron powder in a nylon resin was used. The first magnetic core member 13 was bonded so that the first magnetic core member 13 covered the return path portion 12b from the back surface of the insulating member 11 without overlapping the forward path portion 12a.
A conductive member 16 made of an aluminum plate having a thickness of 0.1 mm and a length and width of 70 mm × 60 mm was bonded to the back surface of the insulating member 11 so as to cover the first magnetic core member 13. Thus, the antenna coil which has only the 1st magnetic core member 13 was made into Example 1. FIG.
[0030]
<Example 2>
An antenna coil having only the same first magnetic core member 13 as in Example 1 was obtained. A second magnetic core member 14 having the same shape and size as the first magnetic core member in the first embodiment was prepared using the same composite material as in the first embodiment. The second magnetic core member 14 is bonded to the surface of the insulating member 11 so as to cover the forward path portion 12a without overlapping the return path portion 12b and to overlap the end portion of the adjacent first magnetic member 13 as shown in FIG. The antenna coil shown in FIG. 4 was obtained. Thus, the antenna coil which has both the 1st magnetic core member 13 and the 2nd magnetic core member 14 was made into Example 2. FIG.
[0031]
<Comparative Example 1>
As shown in FIG. 9, the coil body 2 was formed on a single electrical insulating film as the base plate 1. As the electrical insulating film 1, a polyimide film having a thickness of 50 μm and a length and width of 50 mm each was used. A 35 μm thick copper foil is laminated on the surface of the polyimide film 1 and a conductor is formed by etching the copper foil. The conductor is wound four times in a spiral on one main surface of the polyimide film. The coil body 2 thus formed was formed. The conductor is formed with a width of 0.8 mm, the outer shape of the coil body 2 formed by this conductor is 45 mm × 45 mm, and the central portion surrounded by the coil body 2 is a 37 mm × 37 mm square shape. Formed. A conductive member (not shown) made of an aluminum plate having a thickness of 0.1 mm and a length and width of 70 mm × 60 mm was bonded to the back surface of the base plate 1 made of an electric insulating film. An antenna coil in which a spiral coil body 2 was formed on a base plate 1 made of this electrically insulating film was used as Comparative Example 1.
[0032]
<Comparison test>
As articles, an acrylic plate having a size of 100 mm × 100 mm and a thickness of 0.16 mm, and an aluminum plate and a mild steel plate having the same shape and size as the acrylic plate were prepared. The antenna coils in Examples 1 and 2 and Comparative Example 1 described above were arranged on the surfaces of these acrylic plates, aluminum plates, and mild steel plates, respectively. When arranging the antenna coil, the conductive member was arranged so as to be in direct contact with those articles. Then, a measuring terminal for measuring coil characteristics (4395 manufactured by HEWLETT PACKARD) is connected to both end portions (X and Y in FIG. 2) of the conductor 12 of the antenna coil, and the measuring device determines a predetermined value. The L value and Q value of the coil body with respect to the frequency were measured.
Moreover, the capacitor | condenser 16 was connected to the antenna coil of the comparative example 1 and Example 1, respectively, and the EAS tag which operate | moves at 8.2 MHz was obtained. The presence or absence of operation when this tag was placed on the surface of the above-described acrylic plate, aluminum plate, and mild steel plate was confirmed. These results are shown in Table 1, respectively.
[0033]
[Table 1]

[0034]
As is clear from Table 1, in Example 1 and Example 2, the L value hardly changed on any of the acrylic plate, the aluminum plate, and the mild steel plate, and compared with the case of the acrylic plate also on the aluminum plate and the mild steel plate. As a result, there is little decrease in the Q value. However, in Comparative Example 1, the L value changes significantly on the aluminum plate as compared to the acrylic plate. On the other hand, when it is on a mild steel plate, the Q value is significantly reduced. In the first and second embodiments, the direction of the magnetic flux generated from the coil is parallel to the plane of the plate, whereas in the comparative example, the direction of the magnetic flux is perpendicular to the plane of the plate and the conductive member. This is considered to be caused by the fact that most of the magnetic flux arrives at the plate even when these are bonded. Further, the tag in which the IC chip is connected to the antenna coil of Example 1 and Example 2 operates regardless of the surface of the acrylic plate, the aluminum plate, and the mild steel plate, whereas the antenna of Comparative Example 1 The tag in which the IC chip is connected to the coil operates only when it is disposed on the surface of the acrylic plate, and does not operate when it is disposed on the surface of the aluminum plate and the mild steel plate. This is considered to be because the L value changed in the case of an aluminum plate, the resonance frequency changed, and energy was absorbed by the iron plate, resulting in a loss.
[0035]
【The invention's effect】
As described above, according to the present invention, the insulating member, the series of conductors meandering on the surface of the insulating member and alternately forming the forward path portion and the return path portion, and the first member bonded to the back surface of the insulating member. 1 magnetic core member is provided, the magnetic flux generated by the current flowing through the conductor passes through the first magnetic core member and becomes parallel to the surface of the article to which the antenna coil is attached. Further, since the first magnetic core member is bonded to the back surface of the insulating member so as to cover the return path portion from the back surface of the insulating member without overlapping the forward path portion, the magnetic flux passing through the first magnetic core member is at the end portion thereof. A part of it diffuses and passes over the forward path part, returns to the adjacent first magnetic core member again, and operates reliably without being affected by the article surface even if it is a metal.
[0036]
In addition, if the second magnetic core member is bonded to the surface of the insulating member so as to cover the forward path portion without overlapping the return path portion and the end portion overlaps the end portion of the adjacent first magnetic member, the magnetic flux can be The two magnetic core members pass through the first and second magnetic core members while moving alternately. For this reason, the forward path part and the return path part alternately exist on the front and back of the magnetic flux, and the series of conductors including the forward path part and the backward path part are the same as the antenna coil wound around the magnetic flux. Thus, an antenna coil having the same characteristics as a conventional antenna coil manufactured by winding a conducting wire around the outer peripheral surface of the magnetic core member can be obtained relatively easily, and its mass productivity can be improved. Furthermore, if a series of conductors are formed by a plurality of conductive wires meandering on the surface of the insulating member so as to be along each other at a predetermined interval, the forward path portions alternately present on the front and back of the magnetic flux By increasing the number of return paths, the number of windings can be easily increased, and the characteristics of the antenna coil can be improved by increasing the number of windings.
[0037]
Furthermore, if the conductor is formed by etching or punching, or screen printing or vapor deposition, the formation of the conductor on the insulating member becomes relatively easy, and the first or second magnetic core member is made of a soft magnetic metal, If the powder or flake made of amorphous or ferrite and a composite of plastic, soft magnetic metal plate or foil, amorphous foil or laminated material thereof, or ferrite, the magnetic core member becomes relatively thin, and the entire antenna coil The thickness can be reduced. In particular, by using a magnetic coating film as a magnetic core member, the magnetic core member can be further thinned, and a thinner antenna coil can be obtained by a magnetic core member having a thickness of 0.8 mm or less, which is difficult to form in injection molding. Is possible.
[Brief description of the drawings]
1 is a cross-sectional view taken along line AA of FIG. 2 showing an antenna coil according to a first embodiment of the present invention.
FIG. 2 is a plan view of the antenna coil.
FIG. 3 is a cross-sectional view corresponding to FIG. 1 showing an antenna coil according to a second embodiment of the present invention.
FIG. 4 is a plan view of the antenna coil.
FIG. 5 is a cross-sectional view corresponding to FIG. 1, showing an antenna coil according to a third embodiment of the present invention.
FIG. 6 is a plan view of the antenna coil.
FIG. 7 is a plan view of an antenna coil having a conductor made of three conductive wires.
FIG. 8 is a perspective view showing a conventional antenna coil having a conductor spirally wound around a magnetic core member.
FIG. 9 is a perspective view showing a conventional antenna coil composed of a spiral coil body.
[Explanation of symbols]
11 Insulating material
12 Conductor
12a, 21a, 22a Outward part
12b, 21b, 22b Return part
13 First magnetic core member
14 Second magnetic core member
16 Conductive member
21, 22 Conductor wire

Claims

An insulating member (11) formed of an electric insulating film or an electric insulating sheet;
A series of conductors (12) meandering on the surface of the insulating member (11) and alternately forming forward paths (12a) and return paths (12b);
The bonded to the back surface of the insulating member (11) said forward portion each of the return portion without overlapping with (12a) said insulating member (12b) (11) a plurality of first magnetic core member for covering from the rear surface (13) An antenna coil comprising:

A plurality of second magnetic core members (14) cover each forward path portion (12a) without overlapping the return path portion (12b) on the surface of the insulating member (11), and the first magnetic member (13) whose end portion is adjacent The second magnetic core member (14) is bonded so as to overlap with the end of the first magnetic core member (13), and the second magnetic core member (14) transmits the magnetic flux passing through the first magnetic core member (13) to the surface side of the insulating member (11) in the forward path portion (12a) The antenna coil according to claim 1, wherein the antenna coil is configured to lead to

The conductor (12) has a plurality of conductive lines (21, 22) formed meandering on the surface of the insulating member (11) so as to be along each other at a predetermined interval, and the conductive line (21) The antenna coil according to claim 1 or 2, wherein a series of conductors (12) is configured by connecting a terminal portion of each of said conductors to a starting end portion of an adjacent conductive wire (22).

By etching the conductive foil adhered to the entire surface of the insulating member (11) with a predetermined pattern, or screen printing or vapor-depositing a conductive material with a predetermined pattern on the surface of the insulating member (11), The antenna coil according to any one of claims 1 to 3, wherein a conductor (12) is formed on a surface of the insulating member (11).

Either one or both of the first magnetic core member (13) and the second magnetic core member (14) is a composite material of soft magnetic metal, powder or flakes made of amorphous or ferrite and plastic, soft magnetic metal plate or foil The antenna coil according to any one of claims 1 to 4, wherein the antenna coil is amorphous foil or a laminated material thereof, or ferrite.

One or both of the first magnetic core member (13) and the second magnetic core member (14) are formed by applying and drying ink or paint containing magnetic powder on the insulating member (11). The antenna coil according to claim 1, comprising:

The antenna coil according to any one of claims 1 to 6, wherein a sheet-like or plate-like conductive member (16) is bonded to the back surface of the insulating member (11) so as to cover the first magnetic core member (13).