【０００１】
【発明の属する技術分野】
本発明は、接点ばね及びこれを用いたスイッチ装置に係り、携帯電話など小型の電子機器の押釦スイッチに好適な接点ばね及びこれを用いたスイッチ装置の構造に関する。
【０００２】
【従来の技術】
従来の接点ばね及びこれを用いたスイッチ装置の構造としては、固定接点が形成された基台と、この基台上に固定接点と対向配置されたドーム状の反転部を有する接点ばねとから構成されている。
【０００３】
接点ばねは、上面側に押圧操作用のキートップが配設されて使用されるものとなっており、電子機器の化粧パネル側からこのキートップを押圧することにより、接点ばねの上面が押圧されて、下面に一体的に形成された接点部が反転して固定接点と接触することにより、接点の切り換えが行われるものである。
【０００４】
押圧操作用のキートップの下面には、ドーム状の接点ばねの頂部を押圧するための突起が一体形成されており、キートップが押圧されると、その押圧力がこの突起を介して接点ばねの頂部に伝達されるため、接点ばねがクリック感を伴って反転して固定接点に接触するものとなる。
【０００５】
この場合、キートップ下面の突起と、接点ばねのドーム頂部との間に相対位置のバラツキがあると、操作フィーリングに影響してくることから、これを解決するために、従来の構成においては、キートップ下面の突起の代りに、接点ばねの上面に樹脂で突起を形成することにより、キートップの押圧力を接点ばねのドーム頂部に伝達する構造が知られている（例えば、特許文献１）。
【０００６】
しかし、上記の接点ばね及びこれを用いたスイッチ装置の構造は、接点ばねのドーム頂部に印刷などにより樹脂を盛って突起を形成するため、突起の厚みのコントロールが難しく、精度良く形成することが困難であった。
そこで、本出願人は、接点ばねのドーム頂部に、金属材からなる突起部材をかしめて突起部を形成する構成の接点ばね（接点板）の出願を行った（特願２００２−０２９２６８号参照）。
【０００７】
この構造によれば、押圧部を容易に接点ばねの膨出部の頂部に形成でき、キートップとの相対位置ずれがあっても、接点ばねの膨出部の頂部に確実に押圧力を伝達することができ、良好なフィーリングが得られるものとなっている。
【０００８】
【特許文献１】
特開平１１−００７８６２号公報
【０００９】
【発明が解決しようとする課題】
しかしながら、上述した従来の接点ばね及びこれを用いたスイッチ装置の構造においては、接点ばねにばね特性に優れた材料を用い、突起部材には、かしめて固定する際の加工性と、接点面の形成のための加工性を考慮して、加工性の良い材料を用いることが好ましく、各々異なる金属を用いることになるが、そのため、異種金属間での接合部分が酸化することにより高抵抗値となり、スイッチ用の接点ばねとして使用する場合には電気特性に影響がでることで信頼性が悪いという問題があった。
【００１０】
したがって、本発明では上述した問題点を解決し、接点ばねへの突起部の形成を容易に行うことができると共に、突起部との接合部の抵抗値を低減し、信頼性の高い接点ばね及びこれを用いたスイッチ装置を提供することを目的とする。
【００１１】
【課題を解決するための手段】
上記課題を解決するために本発明では第１の手段として、接点ばねは、反転可能な膨出部を有し、この膨出部の頂部に貫通孔が形成されたばね部材と、前記貫通孔に挿入され、一端が前記ばね部材の板厚方向の上面側に突出して保持された突起部材と、この突起部材の上面側に形成され、外部からの押圧力を伝達する押圧部と、この押圧部の他端側を前記ばね部材の膨出部の下面側に突出させて形成した接点部とを備え、前記突起部材は、前記ばね部材の板厚方向の上下両面から挟み込むように前記突起部材の外周部を変形させて前記貫通孔に抜け止め保持されており、前記突起部材の外周部と接合する前記ばね部材の貫通孔の周縁部の上下両面には、導電性に富んだ貴金属からなる被覆材を被覆したことを特徴とする。
【００１２】
また、第２の手段として、前記ばね部材は、上下両面に貴金属のめっきが施された処理鋼板からなり、これを板厚方向に打ち抜くことにより前記被覆材を有する貫通孔を形成したことを特徴とする。
また、第３の手段として、前記ばね部材の貫通孔の内周面にも、前記被覆材を施すようにしたことを特徴とする。
【００１３】
また、第４の手段として、接点ばねは、反転可能な膨出部を有し、この膨出部の頂部に貫通孔が形成されたばね部材と、前記貫通孔に挿入され、一端が前記ばね部材の板厚方向の上面側に突出して保持された突起部材と、この突起部材の上面側に形成され、外部からの押圧力を伝達する押圧部と、この押圧部の他端側を前記ばね部材の膨出部の下面側に突出させて形成した接点部とを備え、前記突起部材は、前記ばね部材の板厚方向の上下両面から挟み込むように前記突起部材の外周部を変形させて前記貫通孔に抜け止め保持されており、前記ばね部材の貫通孔の周縁部と接合する前記突起部材の外周部には、導電性に富んだ貴金属からなる被覆材を被覆したことを特徴とする。
【００１４】
また、第５の手段として、前記突起部材は、導電性に優れた貴金属の材料からなり、この外周部で前記被覆材を構成したことを特徴とする。
【００１５】
また、第６の手段として、スイッチ装置は、第１乃至第５の手段の何れかに記載の接点ばねと、固定接点と、この固定接点と導通する外部接続端子が配設された基台とを備え、前記接点ばねの接点部を前記固定接点に対向させると共に、外部から前記押圧部を操作可能に前記基台上に配置したことを特徴とする。
【００１６】
【発明の実施の形態】
以下、本発明の実施の形態を図１乃至図９に示す。図１は本発明の接点ばねの断面図、図２は接点ばねの接合部分の部分断面図、図３は接点ばねの接合部分の他の実施例の部分断面図、図４乃至図６は接点ばねの製造工程を示し、図４は突起部材のかしめ前の部分詳細図、図５はかしめ時の金型との関係を示す部分詳細図、図６はかしめ後の部分詳細図、図７は接点ばねを実装したスイッチ装置の平面図、図８は同じくスイッチ装置の断面図、図９は接点ばねを実装した他のスイッチ装置の一部を破断した分解斜視図である。
【００１７】
図１及び図２において、接点ばね１は、りん青銅又はステンレスなどの金属薄板を略円盤状に打ち抜いた導電性のばね部材から形成されており、外周縁部１ａから中心部に向かって所定角度で立ちあがるスカート部１ｂと、このスカート部１ｂに連続してドーム状に膨出した頂部１ｃとがプレスなどの方法で形成されている。また、前記頂部１ｃの中央には板厚方向に貫通する貫通孔１ｄが形成されており、この貫通孔１ｄ内には導電材料で略円柱状に形成された突起部材２が、前記貫通孔１ｄの上下方向に貫通した状態で抜け止め固定されている。
【００１８】
前記突起部材２の上面側には、外部からの押圧力を伝達す押圧部２ａが形成されており、また、下面側には、前記ばね部材の膨出部の下面側に突出させて接点部２ｂが形成されている。前記押圧部２ａの中央部には、円状の凹部２ｃが形成されており、この凹部２ｃを設けることにより、前記押圧部２ａの外周部の肉厚が、前記押圧部２ａの中央部の肉厚よりも厚くなるように形成されている。また、前記接点部２ｂの表面には、十字状の溝部２ｄが形成されており、この溝部２ｄによって複数に分割された四角部が突起状となって前記接点部２ｂの接点面を構成している。また、この接点部２ｂには銀めっきなどの表面処理が施されたものとなっている。
【００１９】
また、前記接点ばね１のばね部材の上下両面には、銀などの貴金属からなる被覆材３でめっきなどの表面処理（被覆）が施されており、ばね部材の前記貫通孔１ｄの周縁部の被覆材３と、前記突起部材２の外周部とが密着して接合されて抜け止め保持されている。
【００２０】
このように、前記突起部材２の外周部と接合するばね部材の前記貫通孔１ｄの周縁部の上下両面には、導電性に富んだ貴金属からなる前記被覆材３が被覆してあるので、前記貫通孔１ｄの周縁部が、硬度の低い（軟らかい）クッション性のあるめっき層で塞がれることになり、互いの密着性が向上することにより酸化が抑制されるので、導電性が向上されるものとなる。その結果、互いの接合部の抵抗値が低減されるので接触信頼性の高い接点ばね１が得られる。
【００２１】
この場合、前記接点ばね１のばね部材として、予め両面に貴金属のめっきが施された処理鋼板を使用して、板厚方向に略円盤状に打ち抜くことにより前記接点ばね１を形成しても良く、この場合には、めっき工程が省けるので、前記突起部材２との接合部の抵抗値の低い材料からなるばね部材を簡単に形成できると共に、コストの削減が図れるものとなる。
【００２２】
図３は、前記接点ばね１のばね部材の前記貫通孔１ｄの内周面（打ち抜きによる破断面）にも、前記被覆材３を施すようにした接点ばね１の構成を示している。この場合には、更に、前記突起部材２との接合部の密着性が向上され、導電性が向上されるので、更に、接合部の抵抗値の低減が図れるものとなっている。
【００２３】
前記突状部材２を、前記接点ばね１のばね部材へ固着する場合には、まず、図２に示すように、予め片面に銀めっきなどの表面処理が施された黄銅などの導電性の金属柱からなる突起部材２を、前記貫通孔１ｄの内径よりもわずかに小径となるように形成する。この場合、前記金属柱は接点面となる片面に銀めっきなどを施した金属板材を打ち抜いて形成するようにしても良い。そして、前記金属柱からなる突起部材２を略円盤状の外形に打ち抜かれた前記ばね部材の貫通孔１ｄ内にめっき面が下面側になるように配置する。
【００２４】
次に、図３に示すように、前記金属柱からなる突起部材２を上下方向から上型Ｊと下型Ｋとで挟み込んで加圧変形させることにより、前記突起部材２の外周部を前記ばね部材の貫通孔１ｄの内縁に食い込ませて抜け止めを形成し保持させる。また、同時に、前記突起部材の上面には前記押圧部２ａを、下面には前記接点部２ｂを形成する。
【００２５】
この時、前記上型Ｊの前記突起部材２の押圧部２ａとの当接面の中央には凸部Ｊａが形成されており、前記突起部材２の加圧変形時に、前記凸部Ｊａによって前記押圧部２ａの上面側の肉厚が中央部から外周部方向へ押し広げられるようになっている。そして、この結果、前記押圧部２ａの中央には円状の前記凹部２ｃが形成されるものとなる。
【００２６】
また、前記下型Ｋの前記突起部材２の接点部２ｂとの当接面には十字状の突出部Ｋａが形成されており、前記突起部材２の加圧変形時に、前記突出部Ｋａによって前記突起部材２の下面側の肉厚が十字状の四角方向へ押し広げられるようになっている。そして、この結果、前記接点部２ｂには、十字状の前記溝部２ｄが形成され、この溝部２ｄによって複数に分割された四角部が突起状となって前記接点部２ｂの接点面を構成するものとなる。
【００２７】
これにより、図４に示すように、前記突起部材２は、前記ばね部材の板厚方向の上下両面から挟み込むように前記突起部材２の外周部を変形させて前記ばね部材の貫通孔１ｄに抜け止め保持されるものとなる。
そして、このようにして前記突起部材２が一体化された前記ばね部材を、図示しないプレス金型によって絞り加工することにより、前記ばね部材に前記スカート部１ｂと頂部１ｃとを有するドーム状の膨出部が形成されて前記接点ばね１が形成されるものとなっている。
【００２８】
このように、予め前記ばね部材に前記突起部材２を一体化しておき、しかる後に前記ばね部材をプレス成形してドーム状に形成することにより、反転可能な膨出部と外部からの押圧部２ａを精度良く形成することができる。また、前記突状部材２を導電材料で形成することにより、前記押圧部２ａに対して前記接点部２ｂをも精度良く形成することができる。
【００２９】
上記のようにして形成された前記接点ばね１は、前記外周縁部１ａの下面を被支持面として後述する周辺固定接点上に配置されて、前記押圧部２ａの外部からの押圧によって前記頂部１ｃが反転して、前記接点部２ｂが中央固定接点と接触可能となっている。そして、固定接点に接触する前記外周縁部１ａの下面及び前記接点部２ｂとが銀などの貴金属のめっき処理面となるため、接点間の導通を確実に行うことができる。
【００３０】
尚、上記実施例においては、前記接点ばね１のばね部材の両面に、銀などの貴金属からなる前記被覆材３でめっきなどの表面処理（被覆）が施された構成とし、前記ばね部材の貫通孔１ｄの周縁部の被覆材３と、導電材料からなる前記突起部材２の外周部とが密着して接合されて保持される構成としたが、これとは逆に、前記突起部材２の外周部に、銀などの貴金属からなる前記被覆材３でめっきなどの表面処理（被覆）を施した構成とし、前記突起部材２の外周部の被覆材３と、導電材料からなる前記ばね部材の貫通孔１ｄの周縁部とが密着して接合される構成としても良い。この場合には、前記ばね部材の下面側で周辺固定接点と接触する部分には銀などのめっき処理を施しておくものとする。
また、この場合に、前記突起部材２を、導電性に優れた貴金属の材料（例えば銀線、洋白条など）で一体的に形成するようにしても良く、この場合には、めっき工程が省ける。
【００３１】
上記構成においても、前記ばね部材の貫通孔１ｄの周縁部と接合する前記突起部材２の外周部には、導電性に富んだ貴金属からなる前記被覆材３が被覆してあるので、前記突起部材２の外周部が、硬度の低い（軟らかい）クッション性のある被覆層で塞がれることになり、互いの密着性が向上することにより酸化が抑制されるので、導電性が向上されるものとなる。その結果、互いの接合部の抵抗値が低減されるので接触信頼性の高い接点ばね１が得られる。
また、前記突起部材２を、導電性に優れた貴金属の材料で一体的に形成した場合には、接合部の抵抗値の低い材料からなる突起部材を簡単に形成できる。
【００３２】
次に、図７及び図８で前記接点ばね１を実装したスイッチ装置の構成について説明する。図７及び図８は、上記した接点ばね１を単キースイッチとして構成した場合の押釦スイッチの構成を示す。
【００３３】
押釦スイッチ１０の基台としてのハウジング１１は合成樹脂などの絶縁材からなり、矩形状の底板部１１ａの外周を環状に取り囲んで起立する側壁１１ｂによって上部が開放された箱状の収納部１２が形成されている。そして、このハウジング１１の底板部１１ａには、導電性の金属材からなる一対の端子材がインサート成形されており、その一端が底板部１１ａ内で屈曲されて前記収納部１２内に突出して中央固定接点１６ａが形成されている。
また、他方の端子材の一端は、底板部１１ａ内で二股に分岐して各々が前記収納部１２内に中央固定接点１６ａを挟んで突出して一対の周辺固定接点１６ｂが設けられている。
【００３４】
中央固定接点１６ａは、ハウジング１１の収納部１２の略中央に位置し、収納部１２への底板部１１ａからの突出量が、中央固定接点１６ａに対して周辺固定接点１６ｂが若干高くなるように形成されている。
そして、中央固定接点１６ａに接続した端子材の他端部は、ハウジング１１外に導出されて前記側壁１１ｂに沿って曲げられ面実装用の半田付け部を有する外部接続端子１５ａが形成されている。同様に、周辺固定接点１６ｂに接続した端子材の他端部には、面実装用の半田付け部を有する外部接続端子１５ｂが形成されている。
【００３５】
そして、前記接点ばね１が前記ハウジング１１の凹状の収納部１２に収容され、その外周縁部１ａが周辺固定接点１６ｂ上に載置されて常時接触すると共に、接点部２ｂが中央固定接点１６ａ上に接離可能に対向配置されて可動接点を形成している。また、前記ハウジング１１内に収納された前記接点ばね１は、その上面が絶縁性の粘着シート１３によって覆われている。そして、前記粘着シート１３の貼付けしろ１３ａが前記ハウジング１１の上面に粘着層によって固着されて外部からの塵埃の侵入を防止している。
【００３６】
次に、上記構成の押釦スイッチ１０の動作について説明する。
押釦スイッチ１０の押圧部２ａの非押圧時には、前記接点ばね１のばね力によって、中央固定接点１６ａと接点部２ｂとは離間しており、スイッチは電気的にオフ状態となっている。
【００３７】
この状態から、前記押圧部２ａが図示しないキートップなどで押圧操作されると、粘着シート１３を撓ませながら接点ばね１が座屈反転してクリック感を創出すると共に、中央固定接点１６ａと接点部２ｂとが接触し、スイッチが電気的にオン状態となり、外部接続端子１５ａ、１５ｂを通じて、電子機器へ信号が送出されるものとなる。
【００３８】
この時、前記接点ばね１の頂部１ｃには、前記押圧部２ａが形成されているため、キートップの取り付け誤差や、押圧時の傾きなどにより、接点ばね１の頂部との相対位置ずれが発生したとしても、キートップからの押圧力を接点ばね１に確実に付与でき、良好な操作フィーリングが得られる。また、前記ばね部材の貫通孔１ｄの周縁部と前記接点部２ｂを有する突起部材２の外周部とが、導電性に富んだ貴金属からなる前記被覆材３を介して接合してあるので、導電性が向上され接合部の抵抗値が低減されるので、信頼性の高いスイッチ装置を提供することができる。
【００３９】
図９に示すのは、前記接点ばね１を固定接点が形成された接点基板上に多数実装してシート状スイッチ装置を構成したものである。
シート状スイッチ装置４０における基台としての接点基板３０は、絶縁性の樹脂などの積層板から形成されており、その表面に銅箔や、カーボンなどにより複数組みの固定接点３１が形成されている。この固定接点３１は、環状に形成された周辺固定接点３１ｂの内側に離間させて中央固定接点３１ａが配設されてなり、各々が接続パターンによって外部端子に接続されている。そして、この周辺固定接点３１ｂに上記接点ばね１の外周縁部１ａが常時導通可能に載置されると共に、接点ばね１の接点部２ｂが中央固定接点３１ａ上に接離可能に対向配置されて可動接点を形成している。
【００４０】
また、接点ばね１は、押圧部２ａを設けた側が、下面に粘着層を形成した絶縁性の可撓性粘着シート３５によって覆われている。そして、粘着シート３５の貼付けしろ３５ａに形成された粘着層によって、接点基板３０の上面に固着されてシート状スイッチ装置４０が形成されると共に、接点部内への外部からの塵埃の侵入を防止している。
【００４１】
上記のように構成されたシート状スイッチ装置４０は、可撓性粘着シート３５の上面にキートップを配置して電子機器に組み込まれるが、この組込み時にキートップと接点ばね１との相対位置にずれが生じたとしても、キートップからの押圧力を押圧部２ａを介して接点ばね１に確実に付与でき、良好な操作フィーリングが得られるものとなっている。また、前記接点ばね１のばね部材と前記接点部２ｂを有する突起部材２とが導電性に富んだ貴金属からなる前記被覆材３を介して接合してあるので、接合部の抵抗値を低減し信頼性の高いスイッチ装置を提供することができる。
【００４２】
【発明の効果】
以上説明したように、本発明の接点ばねは、反転可能な膨出部を有し、この膨出部の頂部に貫通孔が形成されたばね部材と、貫通孔に挿入され、一端がばね部材の板厚方向の上面側に突出して保持された突起部材と、この突起部材の上面側に形成され、外部からの押圧力を伝達する押圧部と、この押圧部の他端側をばね部材の膨出部の下面側に突出させて形成した接点部とを備え、突起部材は、ばね部材の板厚方向の上下両面から挟み込むように突起部材の外周部を変形させて貫通孔に抜け止め保持されており、突起部材の外周部と接合するばね部材の貫通孔の周縁部の上下両面には、導電性に富んだ貴金属からなる被覆材を被覆したことから、接点部が設けられた突起部材の外周部と接合する貫通孔の周縁部が、硬度の低い（軟らかい）クッション性のある被覆層で塞がれるため、互いの密着性が向上して酸化が抑制され、導電性が向上されるので、接合部の抵抗値の低減が図れる。
【００４３】
また、ばね部材は、上下両面に貴金属のめっきが施された処理鋼板からなり、これを板厚方向に打ち抜くことにより被覆材を有する貫通孔を形成したことから、接合部の抵抗値の低い材料からなるばね部材を簡単に形成できると共に、コストの削減が図れる。
また、ばね部材の貫通孔の内周面にも、被覆材を施すようにしたことから、さらに、接合部の密着性が向上され、導電性が向上されるので、接合部の抵抗値の低減が図れる。
【００４４】
また、接点ばねは、反転可能な膨出部を有し、この膨出部の頂部に貫通孔が形成されたばね部材と、前記貫通孔に挿入され、一端が前記ばね部材の板厚方向の上面側に突出して保持された突起部材と、この突起部材の上面側に形成され、外部からの押圧力を伝達する押圧部と、この押圧部の他端側を前記ばね部材の膨出部の下面側に突出させて形成した接点部とを備え、前記突起部材は、前記ばね部材の板厚方向の上下両面から挟み込むように前記突起部材の外周部を変形させて前記貫通孔に抜け止め保持されており、前記ばね部材の貫通孔の周縁部と接合する前記突起部材の外周部には、導電性に富んだ貴金属からなる被覆材を被覆したことから、同様に、ばね部材の貫通孔の周縁部と接合する突起部材の外周部が、硬度の低い（軟らかい）クッション性のある被覆層で塞がれるため、互いの密着性が向上して酸化が抑制され、導電性が向上されるので、接合部の抵抗値の低減が図れる。
【００４５】
また、突起部材は、導電性に優れた貴金属の材料からなり、この外周部で被覆材を構成したことから、接合部の抵抗値の低い材料からなる突起部材を簡単に形成できる。
【００４６】
また、スイッチ装置は、第１乃至第５の手段の何れかに記載の接点ばねと、固定接点と、この固定接点と導通する外部接続端子が配設された基台とを備え、接点ばねの接点部を固定接点に対向させると共に、外部から押圧部を操作可能に基台上に配置したことから、キートップと接点ばねとの間に相対位置ずれが生じた場合であっても、接点ばねの膨出部の頂部へキートップの押圧力を確実に伝達することができ、良好な操作フィーリングが得られると共に、接合部の抵抗値を低減し信頼性の高いスイッチ装置を提供できる。
【図面の簡単な説明】
【図１】本発明の一実施例である接点ばねを示す断面図である。
【図２】本発明の接点ばねの接合部分を示す部分断面図である。
【図３】本発明の接点ばねの接合部分の他の実施例を示す部分断面図である。
【図４】本発明の突起部材のかしめ前の状態を示す部分詳細図である。
【図５】本発明の突起部材のかしめ時の金型との関係を示す部分詳細図である。
【図６】本発明の突起部材のかしめ後の状態を示す部分詳細図である。
【図７】本発明の接点ばねを実装したスイッチ装置を示す平面図である。
【図８】本発明の接点ばねを実装したスイッチ装置を示す断面図である。
【図９】本発明の接点ばねを実装した他のスイッチ装置の一部を破断した状態を示す分解斜視図である。
【符号の説明】
１ 接点ばね（ばね部材）
１ａ 外周縁部
１ｂ スカート部
１ｃ 頂部
１ｄ 貫通孔
２ 突起部材
２ａ 押圧部
２ｂ 接点部
２ｃ 凹部
２ｄ 溝部
３ 被覆材
１０ 押釦スイッチ
１１ ハウジング
１１ａ 底板部
１１ｂ 側壁
１２ 収納部
１３ 粘着シート
１３ａ 貼付けしろ
１５ａ，１５ｂ 外部接続端子
１６ 固定接点
１６ａ 中央固定接点
１６ｂ 周辺固定接点
３０ 接点基板
３１ 固定接点
３１ａ 中央固定接点
３１ｂ 周辺固定接点
３５ 可撓性粘着シート
３５ａ 貼付けしろ
４０ シート状スイッチ装置
Ｊ 上型
Ｊａ 凸部
Ｋ 下型
Ｋａ 突出部[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a contact spring and a switch device using the same, and more particularly to a contact spring suitable for a push button switch of a small electronic device such as a mobile phone and a structure of a switch device using the same.
[0002]
[Prior art]
The structure of a conventional contact spring and a switch device using the same includes a base on which a fixed contact is formed, and a contact spring having a dome-shaped reversing portion disposed on the base so as to face the fixed contact. Have been.
[0003]
The contact spring has a key top for pressing operation disposed on the upper surface side and is used. By pressing the key top from the decorative panel side of the electronic device, the upper surface of the contact spring is pressed. Thus, the contact portion integrally formed on the lower surface is inverted and comes into contact with the fixed contact, thereby switching the contact.
[0004]
A projection for pressing the top of the dome-shaped contact spring is integrally formed on the lower surface of the key top for pressing operation. When the key top is pressed, the pressing force is applied to the contact spring via the projection. , The contact spring is inverted with a click feeling and comes into contact with the fixed contact.
[0005]
In this case, if there is a variation in the relative position between the projection on the lower surface of the key top and the dome top of the contact spring, the operation feeling will be affected. There is known a structure in which a pressing force of a key top is transmitted to a dome top of a contact spring by forming a projection with a resin on the upper surface of a contact spring instead of the protrusion on the lower surface of the key top (for example, Patent Document 1). ).
[0006]
However, in the structure of the contact spring and the switch device using the contact spring, since the protrusion is formed by applying resin on the top of the dome of the contact spring by printing or the like, it is difficult to control the thickness of the protrusion, and it is difficult to accurately form the protrusion. It was difficult.
Accordingly, the present applicant has filed an application for a contact spring (contact plate) having a configuration in which a protrusion made of a metal material is formed on the top of the dome of the contact spring to form a protrusion (see Japanese Patent Application No. 2002-029268). .
[0007]
According to this structure, the pressing portion can be easily formed on the top of the bulging portion of the contact spring, and even if there is a relative displacement with the key top, the pressing force is reliably transmitted to the top of the bulging portion of the contact spring. And a good feeling can be obtained.
[0008]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 11-007862
[Problems to be solved by the invention]
However, in the structure of the above-mentioned conventional contact spring and the switch device using the same, a material having excellent spring characteristics is used for the contact spring, and the workability when caulking and fixing the contact member and the contact surface are improved. In consideration of workability for forming, it is preferable to use a material having good workability, and different metals are used, however, a high resistance value is obtained by oxidizing a joint between different metals. However, when used as a contact spring for a switch, there is a problem in that the electrical characteristics are affected and the reliability is poor.
[0010]
Therefore, the present invention solves the above-described problems, facilitates formation of the protrusion on the contact spring, reduces the resistance value of the joint with the protrusion, and increases the reliability of the contact spring. An object is to provide a switch device using the same.
[0011]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, in the present invention, as a first means, the contact spring has a reversible bulging portion, and a spring member having a through-hole formed at the top of the bulging portion; A protruding member which is inserted and one end of which protrudes and is held on the upper surface side in the plate thickness direction of the spring member; a pressing portion formed on the upper surface side of the protruding member for transmitting a pressing force from the outside; And a contact portion formed by projecting the other end of the spring member to the lower surface side of the bulging portion of the spring member. An outer peripheral portion is deformed and held in the through hole so as to be retained. The upper and lower surfaces of a peripheral portion of the through hole of the spring member joined to the outer peripheral portion of the projection member are covered with a precious metal having high conductivity. The material is covered.
[0012]
As a second means, the spring member is made of a treated steel plate having upper and lower surfaces plated with a noble metal, and punched in the thickness direction to form a through hole having the coating material. And
As a third means, the coating material is applied to the inner peripheral surface of the through hole of the spring member.
[0013]
As a fourth means, the contact spring has a reversible bulging portion, a spring member having a through hole formed at the top of the bulging portion, and a spring member inserted into the through hole, one end of which is the spring member. A protruding member protruding from the upper surface side in the thickness direction of the protruding member, a pressing portion formed on the upper surface side of the protruding member and transmitting an external pressing force, and the other end of the pressing portion being a spring member. And a contact portion formed by protruding from the lower surface side of the bulging portion. The projecting member deforms an outer peripheral portion of the projecting member so as to sandwich the spring member from both upper and lower surfaces in a thickness direction of the spring member, and The outer peripheral portion of the projection member, which is retained and retained in the hole and joined to the peripheral portion of the through hole of the spring member, is coated with a coating material made of a highly conductive noble metal.
[0014]
As a fifth means, the projecting member is made of a precious metal material having excellent conductivity, and the covering material is formed on an outer peripheral portion thereof.
[0015]
Further, as a sixth means, the switch device comprises a contact spring according to any one of the first to fifth means, a fixed contact, and a base provided with an external connection terminal electrically connected to the fixed contact. A contact portion of the contact spring is opposed to the fixed contact, and the pressing portion is arranged on the base so as to be operable from outside.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention is shown in FIGS. 1 is a sectional view of a contact spring according to the present invention, FIG. 2 is a partial sectional view of a joint portion of the contact spring, FIG. 3 is a partial sectional view of another embodiment of the joint portion of the contact spring, and FIGS. FIG. 4 is a partial detailed view of the spring member before caulking, FIG. 5 is a partial detailed view showing the relationship with the mold at the time of caulking, FIG. 6 is a partial detailed view after caulking, and FIG. FIG. 8 is a plan view of the switch device having the contact spring mounted thereon, FIG. 8 is a cross-sectional view of the same switch device, and FIG. 9 is an exploded perspective view of a part of another switch device having the contact spring mounted thereon.
[0017]
1 and 2, a contact spring 1 is formed of a conductive spring member formed by stamping a thin metal plate such as phosphor bronze or stainless steel into a substantially disk shape, and has a predetermined angle from an outer peripheral edge 1a toward the center. A skirt portion 1b standing up at the bottom and a top portion 1c bulging in a dome shape continuously from the skirt portion 1b are formed by a method such as pressing. A through-hole 1d is formed at the center of the top 1c in the thickness direction, and a projecting member 2 formed of a conductive material in a substantially cylindrical shape is formed in the through-hole 1d. Is secured in such a way that it penetrates vertically.
[0018]
A pressing portion 2a for transmitting a pressing force from the outside is formed on the upper surface side of the projecting member 2, and a contact portion is formed on the lower surface side so as to project toward the lower surface side of the bulging portion of the spring member. 2b is formed. A circular concave portion 2c is formed at the center of the pressing portion 2a. By providing the concave portion 2c, the thickness of the outer peripheral portion of the pressing portion 2a is reduced at the central portion of the pressing portion 2a. It is formed so as to be thicker than the thickness. A cross-shaped groove 2d is formed on the surface of the contact portion 2b, and the quadrangular portion divided into a plurality by the groove 2d forms a projection to form a contact surface of the contact portion 2b. I have. The contact portion 2b is subjected to a surface treatment such as silver plating.
[0019]
The upper and lower surfaces of the spring member of the contact spring 1 are subjected to a surface treatment (coating) such as plating with a coating material 3 made of a noble metal such as silver, so that a peripheral portion of the through hole 1d of the spring member is formed. The coating material 3 and the outer peripheral portion of the protruding member 2 are tightly joined to each other and are retained and retained.
[0020]
As described above, the upper and lower surfaces of the peripheral portion of the through hole 1d of the spring member joined to the outer peripheral portion of the projecting member 2 are covered with the covering material 3 made of a highly conductive noble metal. The periphery of the through-hole 1d is closed by a plating layer having a low hardness (soft) and having a cushioning property. Oxidation is suppressed by improving mutual adhesion, so that conductivity is improved. It will be. As a result, the contact spring 1 with high contact reliability is obtained because the resistance value of the joints is reduced.
[0021]
In this case, the contact spring 1 may be formed by using a treated steel sheet having precious metal plated on both sides in advance as a spring member of the contact spring 1 and punching the contact spring 1 in a substantially disk shape in the thickness direction. In this case, since the plating step can be omitted, a spring member made of a material having a low resistance value at the joint with the projection member 2 can be easily formed, and the cost can be reduced.
[0022]
FIG. 3 shows a configuration of the contact spring 1 in which the coating material 3 is applied to an inner peripheral surface (a cut surface by punching) of the through hole 1 d of the spring member of the contact spring 1. In this case, the adhesion of the joint with the protruding member 2 is further improved, and the conductivity is further improved, so that the resistance of the joint can be further reduced.
[0023]
When the projecting member 2 is fixed to the spring member of the contact spring 1, first, as shown in FIG. 2, a conductive metal such as brass whose one surface is previously subjected to a surface treatment such as silver plating is used. The protrusion member 2 formed of a pillar is formed so as to have a slightly smaller diameter than the inner diameter of the through hole 1d. In this case, the metal column may be formed by punching a metal plate material having one side serving as a contact surface and having silver plating applied thereto. Then, the projecting member 2 formed of the metal column is disposed in the through hole 1d of the spring member punched into a substantially disk-shaped outer shape such that the plating surface is on the lower surface side.
[0024]
Next, as shown in FIG. 3, the outer peripheral portion of the projecting member 2 is subjected to the spring by sandwiching the projecting member 2 made of the metal column between the upper mold J and the lower mold K from above and below and pressing and deforming the same. The inner edge of the through hole 1d of the member is bitten to form and hold a stopper. At the same time, the pressing portion 2a is formed on the upper surface of the projection member, and the contact portion 2b is formed on the lower surface.
[0025]
At this time, a convex portion Ja is formed in the center of the contact surface of the upper die J with the pressing portion 2a of the projecting member 2, and when the projecting member 2 is deformed under pressure, the convex portion Ja causes The thickness of the pressing portion 2a on the upper surface side can be expanded from the central portion toward the outer peripheral portion. As a result, the circular concave portion 2c is formed at the center of the pressing portion 2a.
[0026]
Further, a cross-shaped protrusion Ka is formed on a contact surface of the lower die K with the contact portion 2b of the protrusion member 2, and when the protrusion member 2 is deformed under pressure, the protrusion Ka causes the protrusion Ka to deform. The thickness of the lower surface side of the projecting member 2 can be pushed and spread in a cross-shaped square direction. As a result, the contact portion 2b is formed with the cross-shaped groove 2d, and the quadrangular portion divided by the groove 2d into a plurality of protrusions forms a contact surface of the contact portion 2b. It becomes.
[0027]
Thereby, as shown in FIG. 4, the projecting member 2 deforms the outer peripheral portion of the projecting member 2 so as to be sandwiched from both the upper and lower surfaces in the thickness direction of the spring member, and comes out through the through hole 1d of the spring member. It will be stopped and held.
Then, the spring member integrated with the projection member 2 is drawn by a press die (not shown), so that the spring member has a dome-shaped expansion having the skirt portion 1b and the top portion 1c. An extension is formed to form the contact spring 1.
[0028]
As described above, the projection member 2 is integrated with the spring member in advance, and then the spring member is press-formed to form a dome shape, whereby the reversible bulging portion and the pressing portion 2a from the outside are formed. Can be accurately formed. In addition, by forming the protruding member 2 from a conductive material, the contact portion 2b can be formed with high accuracy with respect to the pressing portion 2a.
[0029]
The contact spring 1 formed as described above is disposed on a peripheral fixed contact, which will be described later, with the lower surface of the outer peripheral edge portion 1a as a supported surface, and the top portion 1c is pressed by the pressing portion 2a from outside. Are reversed, so that the contact portion 2b can contact the central fixed contact. Since the lower surface of the outer peripheral edge portion 1a and the contact portion 2b that come into contact with the fixed contact are plated with a noble metal such as silver, conduction between the contacts can be reliably performed.
[0030]
In the above embodiment, the surface of the spring member of the contact spring 1 is coated (plated) with the coating material 3 made of a noble metal such as silver on both surfaces, and the spring member is penetrated. The coating material 3 at the peripheral edge of the hole 1d and the outer peripheral portion of the projecting member 2 made of a conductive material are tightly joined and held, but conversely, the outer periphery of the projecting member 2 is The part is subjected to a surface treatment (coating) such as plating with the coating material 3 made of a noble metal such as silver, and the coating material 3 on the outer peripheral portion of the projection member 2 and the penetration of the spring member made of a conductive material are provided. A configuration in which the periphery of the hole 1d is closely contacted and joined may be adopted. In this case, a portion of the lower surface of the spring member that contacts the peripheral fixed contact is plated with silver or the like.
Further, in this case, the protrusion member 2 may be integrally formed of a precious metal material having excellent conductivity (for example, a silver wire or a white strip). In this case, the plating step can be omitted. .
[0031]
Also in the above configuration, the outer peripheral portion of the projection member 2 joined to the peripheral edge of the through hole 1d of the spring member is covered with the coating material 3 made of a precious metal having high conductivity. 2 is closed by a coating layer having a low hardness (soft) cushioning property, and oxidation is suppressed by improving adhesion to each other, so that conductivity is improved. Become. As a result, the contact spring 1 with high contact reliability is obtained because the resistance value of the joints is reduced.
Further, when the projection member 2 is integrally formed of a precious metal material having excellent conductivity, the projection member made of a material having a low resistance value at the joint can be easily formed.
[0032]
Next, the configuration of the switch device on which the contact spring 1 is mounted will be described with reference to FIGS. FIGS. 7 and 8 show a configuration of a push button switch when the above-mentioned contact spring 1 is configured as a single key switch.
[0033]
A housing 11 as a base of the push button switch 10 is made of an insulating material such as a synthetic resin, and has a box-shaped storage portion 12 whose upper portion is opened by a side wall 11b which stands around the outer periphery of a rectangular bottom plate portion 11a in a ring shape. Is formed. A pair of terminal materials made of a conductive metal material are insert-molded in the bottom plate portion 11a of the housing 11, and one end thereof is bent in the bottom plate portion 11a and protrudes into the storage portion 12 so as to be centered. A fixed contact 16a is formed.
One end of the other terminal material is bifurcated in the bottom plate portion 11a, and each is provided with a pair of peripheral fixed contacts 16b protruding into the housing portion 12 with the central fixed contact 16a interposed therebetween.
[0034]
The central fixed contact 16a is located substantially at the center of the storage portion 12 of the housing 11, and the amount of protrusion from the bottom plate portion 11a into the storage portion 12 is such that the peripheral fixed contact 16b is slightly higher than the central fixed contact 16a. Is formed.
The other end of the terminal material connected to the central fixed contact 16a is led out of the housing 11 and bent along the side wall 11b to form an external connection terminal 15a having a soldering portion for surface mounting. . Similarly, an external connection terminal 15b having a soldering part for surface mounting is formed at the other end of the terminal material connected to the peripheral fixed contact 16b.
[0035]
The contact spring 1 is accommodated in the concave accommodating portion 12 of the housing 11, and the outer peripheral edge 1a is placed on the peripheral fixed contact 16b to make constant contact, and the contact portion 2b is placed on the central fixed contact 16a. The movable contact is formed so as to be able to contact and separate from the movable contact. The upper surface of the contact spring 1 housed in the housing 11 is covered with an insulating adhesive sheet 13. And, a sticking margin 13a of the adhesive sheet 13 is fixed to the upper surface of the housing 11 by an adhesive layer to prevent intrusion of dust from the outside.
[0036]
Next, the operation of the push button switch 10 having the above configuration will be described.
When the pressing portion 2a of the push button switch 10 is not pressed, the center fixed contact 16a and the contact portion 2b are separated by the spring force of the contact spring 1, and the switch is in an electrically off state.
[0037]
In this state, when the pressing portion 2a is pressed with a key top (not shown) or the like, the contact spring 1 is buckled while bending the adhesive sheet 13 to create a click feeling, and the center fixed contact 16a and the contact are fixed. The switch is electrically turned on by contact with the portion 2b, and a signal is transmitted to the electronic device through the external connection terminals 15a and 15b.
[0038]
At this time, since the pressing portion 2a is formed on the top 1c of the contact spring 1, a relative positional deviation from the top of the contact spring 1 occurs due to a mounting error of the key top, an inclination at the time of pressing, and the like. Even if it does, the pressing force from the key top can be reliably applied to the contact spring 1, and a good operation feeling can be obtained. Further, since the outer peripheral portion of the through-hole 1d of the spring member and the outer peripheral portion of the protrusion member 2 having the contact portion 2b are joined via the covering material 3 made of a highly conductive noble metal, Since the resistance is improved and the resistance value of the junction is reduced, a highly reliable switch device can be provided.
[0039]
FIG. 9 shows a sheet-like switch device in which a large number of the contact springs 1 are mounted on a contact substrate on which fixed contacts are formed.
The contact substrate 30 as a base in the sheet-like switch device 40 is formed from a laminated plate of an insulating resin or the like, and a plurality of sets of fixed contacts 31 are formed on the surface thereof by copper foil, carbon, or the like. . The fixed contact 31 is provided with a central fixed contact 31a spaced apart from a peripheral fixed contact 31b formed in an annular shape, and each is connected to an external terminal by a connection pattern. The outer peripheral edge portion 1a of the contact spring 1 is placed on the peripheral fixed contact 31b so as to be always conductive, and the contact portion 2b of the contact spring 1 is disposed on the central fixed contact 31a so as to be able to contact and separate therefrom. A movable contact is formed.
[0040]
In addition, the contact spring 1 is provided on the side provided with the pressing portion 2a with an insulating flexible adhesive sheet 35 having an adhesive layer formed on the lower surface. Then, the sheet-like switch device 40 is formed by being adhered to the upper surface of the contact substrate 30 by the adhesive layer formed on the adhesive margin 35a of the adhesive sheet 35, and the intrusion of dust from the outside into the contact portion is prevented. ing.
[0041]
The sheet-like switch device 40 configured as described above is installed in an electronic device by disposing a key top on the upper surface of the flexible adhesive sheet 35, and at the time of this assembling, the key top and the contact spring 1 are positioned relative to each other. Even if the displacement occurs, the pressing force from the key top can be reliably applied to the contact spring 1 via the pressing portion 2a, and a good operation feeling can be obtained. Further, since the spring member of the contact spring 1 and the projecting member 2 having the contact portion 2b are joined via the covering material 3 made of a noble metal having high conductivity, the resistance value of the joint is reduced. A highly reliable switch device can be provided.
[0042]
【The invention's effect】
As described above, the contact spring of the present invention has a reversible bulging portion, a spring member having a through-hole formed at the top of the bulging portion, and a spring member inserted into the through-hole and one end of the spring member. A protruding member projecting from the upper surface side in the plate thickness direction and held; a pressing portion formed on the upper surface side of the protruding member to transmit a pressing force from outside; A contact portion formed so as to protrude from the lower surface side of the protruding portion, wherein the protrusion member is deformed at the outer peripheral portion of the spring member so as to be sandwiched from both upper and lower surfaces in the plate thickness direction of the spring member, and is retained in the through hole to be retained. Since the upper and lower surfaces of the peripheral portion of the through hole of the spring member joined to the outer peripheral portion of the projection member are coated with a coating material made of a precious metal having high conductivity, the contact member is provided with a projection member. The periphery of the through hole that joins the outer periphery is low (soft) Because the closed with Deployment resistant is the coating layer, oxidation and improved adhesion to each other is suppressed, since conductivity is improved, it can be reduced in the resistance of the junction.
[0043]
In addition, the spring member is made of a treated steel plate on which both upper and lower surfaces are plated with a noble metal, and a through-hole having a coating material is formed by punching the plate in a thickness direction, so that a material having a low resistance value at a joint portion is formed. And the cost can be reduced.
In addition, since the coating material is also applied to the inner peripheral surface of the through hole of the spring member, the adhesion of the joint is further improved, and the conductivity is improved, so that the resistance value of the joint is reduced. Can be achieved.
[0044]
The contact spring has a reversible swelling portion, a spring member having a through hole formed at the top of the swelling portion, and an upper surface in the thickness direction of the spring member which is inserted into the through hole and has one end. A protruding member protruding and held to the side, a pressing portion formed on the upper surface side of the protruding member and transmitting an external pressing force, and the other end side of the pressing portion being the lower surface of the bulging portion of the spring member A contact portion formed so as to protrude to the side, wherein the projection member deforms an outer peripheral portion of the projection member so as to be sandwiched from both upper and lower surfaces in the thickness direction of the spring member, and is retained and retained in the through hole. The outer peripheral portion of the projection member joined to the peripheral portion of the through hole of the spring member is coated with a coating material made of a precious metal having high conductivity. The outer periphery of the protruding member that joins the part has low hardness (soft Because the closed with a coating layer cushioned, oxidation and improved adhesion to each other is suppressed, since conductivity is improved, it can be reduced in the resistance of the junction.
[0045]
In addition, since the projecting member is made of a precious metal material having excellent conductivity, and the outer peripheral portion constitutes the covering material, the projecting member made of a material having a low resistance value at the joint can be easily formed.
[0046]
Further, the switch device includes the contact spring according to any one of the first to fifth means, a fixed contact, and a base provided with an external connection terminal that is electrically connected to the fixed contact. Since the contact portion is opposed to the fixed contact and the pressing portion is operably arranged on the base from the outside, even if a relative displacement occurs between the key top and the contact spring, the contact spring can be used. The pressing force of the key top can be reliably transmitted to the top of the bulging portion, a good operation feeling can be obtained, and the resistance value of the joining portion can be reduced to provide a highly reliable switch device.
[Brief description of the drawings]
FIG. 1 is a sectional view showing a contact spring according to an embodiment of the present invention.
FIG. 2 is a partial sectional view showing a joint portion of the contact spring of the present invention.
FIG. 3 is a partial cross-sectional view showing another embodiment of the joint portion of the contact spring of the present invention.
FIG. 4 is a partial detailed view showing a state before the caulking of the projection member of the present invention.
FIG. 5 is a partial detailed view showing a relationship between a protrusion member and a mold at the time of caulking according to the present invention.
FIG. 6 is a partial detailed view showing a state after swaging of the projection member of the present invention.
FIG. 7 is a plan view showing a switch device on which the contact spring of the present invention is mounted.
FIG. 8 is a sectional view showing a switch device on which the contact spring of the present invention is mounted.
FIG. 9 is an exploded perspective view showing a state in which a part of another switch device on which the contact spring of the present invention is mounted is broken.
[Explanation of symbols]
1 Contact spring (spring member)
1a Outer peripheral edge 1b Skirt 1c Top 1d Through hole 2 Projecting member 2a Pressing portion 2b Contact 2c Recess 2d Groove 3 Coating material 10 Push button switch 11 Housing 11a Bottom plate 11b Side wall 12 Storage 13 Adhesive sheet 13a Pasting margin 15a, 15b External connection terminal 16 Fixed contact 16a Central fixed contact 16b Peripheral fixed contact 30 Contact board 31 Fixed contact 31a Central fixed contact 31b Peripheral fixed contact 35 Flexible adhesive sheet 35a Pasting margin 40 Sheet switch device J Upper type Ja Convex portion K Lower Mold Ka Projection