JP3882763B2

JP3882763B2 - Speaker diaphragm

Info

Publication number: JP3882763B2
Application number: JP2003041398A
Authority: JP
Inventors: 智今村; 猛平野; 知昭尾形; 敏勝桑波田
Original assignee: Victor Company of Japan Ltd
Current assignee: Victor Company of Japan Ltd
Priority date: 2003-02-19
Filing date: 2003-02-19
Publication date: 2007-02-21
Anticipated expiration: 2023-02-19
Also published as: CN101282596B; CN101282596A; CN101282593B; CN101282593A; JP2004254019A

Description

【０００１】
【発明の属する技術分野】
本発明は、オーディオ用スピーカの技術分野に属し、特にダイナミック・スピーカに用いられるスピーカ用振動板に関する。
【０００２】
【従来の技術】
従来、ダイナミック・スピーカの振動板としては、紙パルプ製、プラスチック製又はアルミ等の金属製のものが殆どであった。これら従来の振動板は均一材料をプレス成形して成るので中心から半径方向の音の伝搬速度があらゆる方向で等しくなっている。したがって、必ず定在波が発生して共振ポイントを持ち、低周波領域での分割振動による音圧周波数特性の悪化を招き、しかも臨場感が欠落するという難点がある。また、紙パルプ製やプラスチック製の振動板は比較的大きな内部損失係数を有するものの、逆に剛性（ヤング率の大小）の点では劣り、音波伝搬速度は小さいので再生音の解像度にやや不満が残る。一方、アルミ等の金属製振動板は音波伝搬速度が高いものの内部損失係数が小さいので振幅の減衰が小さく再生音の区切りが不明瞭となる（所謂、音のメリハリが悪い。）という難点がある。
【０００３】
上記のような一長一短のある既存素材の振動板に代わって、より自然に近い音を再現できるスピーカ用振動板として木製振動板の実現が望まれている。
【０００４】
即ち、木材の音波伝搬速度はその種類によって異なるが、一般に紙パルプよりも高く、さらに木目の方向とその直角方向とで異なり、木目方向（縦方向という。）の伝搬速度は速く、木目と直角方向（横方向という。）の伝搬速度は比較的遅いという異方性の伝搬性質を有している。また、木材は一般にスピーカ用振動板として適当な内部損失係数を有しており、且つ軽量で丈夫（高剛性）である。
【０００５】
したがって、木材そのものを素材とする木製振動板は定在波が発生しにくく共振ポイントが殆ど現れないので分割振動が殆ど発生せず、低周波領域の音圧周波数特性の改善が期待され、既存の紙パルプ製の振動板に比べて再生音の解像度向上や歯切れ良い音の向上が図れるのである。
【０００６】
上記木製振動板若しくは木製振動板を用いたダイナミック・スピーカや木製振動板の製造方法として、例えば以下に挙げる公知文献に種々の提案が既に為されている。
【０００７】
下記［特許文献１］には、木質材の平板状薄板にポリエステル等のプラスチックを含浸硬化したＷＰＣ化処理木材の平面薄板を寸法安定性、内部摩擦、剛性などの特性において優れるスピーカ用平面振動板として用いたスピーカが提案されている。
【０００８】
下記［特許文献２］には、図８の（ａ）、（ｂ）に示す製造手順のように、（ａ）一枚の木材薄板４から中心部に円弧状の切り欠き部１ａを有し、それに連続して扇形の切り欠き部１ｂを有する略ラッパ形状の展開形状である木材シート１を切り出し、（ｂ）木材シート１の扇形状の切り欠き部１ｂの両縁部ｂ１、ｂ２を糊代部分１ｃで互いに接着剤で重ね貼り合わせてラッパ状に形成し、その後にプレス成形してなるコーン振動板５が提案されている。
【０００９】
また、図９の（ａ）、（ｂ）に示す製造手順のように、複数の木材小片シート２ａ、２ｂ・・・、２Ｌを接着剤で貼り合わせて（ｂ）のように略ラッパ状に形成し、その後にプレス成形してなるコーン振動板２が提案されている。また、上記コーン振動板１、２に物理的耐湿処理或いは化学的耐湿処理を加えたコーン振動板が提案されている。
【００１０】
下記［特許文献３］には、８０μｍ以下にスライスされた極薄木材シートと、その裏面に貼付された接着性の樹脂からなる不織布と、から構成される複合シートを、柔軟剤で柔軟化処理して複数枚積層し、さらに加熱及び加圧して円錐形状に成形した音響用振動板が提案されている。
【００１１】
下記［特許文献４］には、扇形形状に切断した平板状の木材薄板を成形時に割れ発生を防止するために高温度の蒸気、熱湯、又はｐＨ１０以上のアルカリ溶液でボイルした後、円錐状にプレス成形してなるコーン振動板が提案されている。
【００１２】
下記［特許文献５］には、１枚の木製シートの一面側に薄い不織布又は和紙を貼着した貼り合わせシートを作成し、これを潤滑剤入りの容器に含浸し、含浸された貼り合わせシートをプレス加熱成形して略ラッパ状に成形したスピーカ用振動板が提案されている。
【００１３】
下記［特許文献６］には、プレス成形時にしわや割れの生じない、かつ、経時変化の少ない木製のスピーカ用振動板を作るために、１枚の木製シートの一面側に薄い不織布又は和紙又はカーボンシートを貼着した貼り合わせシートを作成し、これを熱硬化性樹脂に含浸させた後、プレス加熱成形して略ラッパ状に成形してなるスピーカ用振動板が提案されている。
【００１４】
【特許文献１】
特開昭６２−２２４１９６号公報
【特許文献２】
特開平１−２８８１００号公報
【特許文献３】
特開平５−８３７９２号公報
【特許文献４】
特開平６−１７８３８６号公報
【特許文献５】
特開平１０−３０４４９２号公報
【特許文献６】
特開２０００−５９８８３号公報
【発明が解決しようとする課題】
木製のスピーカ用振動板において特にポイントとなるのは、木材という素材の割れ易いという性質に如何に対処するか、また、成形性の悪さ、経年変化に如何に対処するかである。
【００１５】
この点、［特許文献１］は対象が木製の平面振動板であって、木製であることの特質・利点は示されているものの、略ラッパ状（コーン状）に成形加工する際の問題点に関する技術的資料は平面であるが故に何ら提供されていない。
【００１６】
また、［特許文献２］の図８及び図９のような製造方法では、木材シート１若しくは木材小片シート２ａ、２ｂ・・が木の素材のみの状態で成形されているために、取り扱いの際やプレス成形時に割れが生じてしまったり、木材シートを互いに接着剤で貼り合わせるため、貼着部が障害となって所望の音響特性が得られないという問題や寸法精度が確保できないという問題がある。
【００１７】
また、［特許文献３］の極薄木材シートを複数枚積層してプレス成形する方法は、加工精度に難点があり、接着層が増えて接着剤の重量により振動板自体の重量が増加して所望の音響特性が得られず、多量の接着剤が音圧周波数特性にも悪影響を与えるので好ましくない。
【００１８】
また、［特許文献４］のようにプレス成形前に高温水蒸気やＰＨ１０以上のアルカリ溶液でのボイル処理が含まれる製造工程による場合は、木材の中のリグニンという構成物質をも取り去ってしまうので木材の本来の特徴を発揮できず、音質に悪影響を与えることになる。
【００１９】
そして何よりも上記［特許文献２］、［特許文献３］、［特許文献４］の内容は製造中での割れ、ひび、しわの発生といった不具合が多く発生し、量産面での歩留まりが非常に悪くなって製品化が実現していないのである。
【００２０】
また、［特許文献５］や［特許文献６］における“張り”や“しなやかさ”を引き出すための潤滑剤の含浸及びしわや割れの発生防止、経時変化を防止するための熱硬化性樹脂の含浸後にプレス加熱成形してなるスピーカ用振動板は、前記［特許文献１］〜［特許文献４］に比べて量産に向けた製造工程の優位性は認められるが、未だ十分な成形性、成形処理の確立が達成されたとは言い難く、木製振動板の実用化に向けてより一層の成形性の向上、延いては美しい仕上がりの木製振動板の実現が望まれる。
【００２１】
本発明は、上記事情に鑑みてなされたものであり、オーディオ用スピーカの音響特性改善に有効で量産性に優れる木製のスピーカ用振動板を提供するものである。
【００２２】
【課題を解決するための手段】
本発明は上記課題を解決するために、
（１）１枚の木製シート１０を素材として略ラッパ形状にプレス成形してなるスピーカ用振動板において、１枚の木製シート１０に対して、中心部に頂点が至る略Ｖ字状の切り込み１１及び該切り込みの縁部１１ａ、１１ｂ同士が互いに重ねられて全体が略ラッパ形状に掛止保持されるための噛み合わせ掛止機構１４を設け、前記切り込み１１及び噛み合わせ掛止機構１４を設けた木製シート１０に水分を与えて軟化させるとともに木製シート中に水分を保持する作用を有する潤滑剤１６を含ませ、前記潤滑剤１６が含まされた木製シート１０は前記切り込み１１の縁部１１ａ、１１ｂ同士が互いに重ね合わされて前記噛み合わせ掛止機構１４によって全体が略ラッパ形状に掛止保持された状態で１次プレス加熱成形によって略ラッパ形状に仮成形され、仮成形の後に乾燥され、乾燥後に熱硬化性樹脂１７が含まされ、前記熱硬化性樹脂１７が半乾き状態になるまで５０℃〜６０℃の乾燥温度で略１〜１０分間乾燥が行われて半乾燥され、前記熱硬化性樹脂１７の半乾き状態で２次プレス加熱成形され、前記２次プレス加熱成形の後に防湿剤１８が塗布され、前記防湿剤１８の塗布された木製シート１０に対してボイスコイル用の中心孔２５抜きと外形抜きを行って振動板としての所定寸法形状に成形してなることを特徴とするスピーカ用振動板３０を提供する。
（２）１枚の木製シート１０を素材として略ラッパ形状にプレス成形してなるスピーカ用振動板において、１枚の木製シート１０の一面側に薄い不織布又は和紙１３が貼着されてなる貼り合わせシート１５に対して、中心部に頂点が至る略Ｖ字状の切り込み１１及び該切り込み１１の縁部１１ａ、１１ｂ同士が互いに重ねられて全体が略ラッパ形状に掛止保持されるための噛み合わせ掛止機構１４を設け、前記切り込み１１及び噛み合わせ掛止機構１４を設けた貼り合わせシート１５に水分を与えて軟化させるとともに貼り合わせシート１５中に水分を保持する作用を有する潤滑剤１６を含ませ、前記潤滑剤１６が含まされた貼り合わせシート１５は前記切り込み１１の縁部１１ａ、１１ｂ同士が互いに重ね合わされて前記噛み合わせ掛止機構１４によって全体が略ラッパ形状に掛止保持された状態で１次プレス加熱成形によって略ラッパ形状に仮成形され、仮成形の後に乾燥され、乾燥後に熱硬化性樹脂１７が含まされ、前記熱硬化性樹脂１７が半乾き状態になるまで５０℃〜６０℃の乾燥温度で略１〜１０分間乾燥が行われて半乾燥され、前記熱硬化性樹脂１７の半乾き状態で２次プレス加熱成形され、前記２次プレス加熱成形の後に防湿剤１８が塗布され、前記防湿剤１８の塗布された貼り合わせシート１５に対してボイスコイル用の中心孔２５抜きと外形抜きを行って振動板としての所定寸法形状に成形してなることを特徴とするスピーカ用振動板４０を提供する。
【００２３】
【発明の実施の形態】
本発明に係るスピーカ用振動板の実施の形態について図面に基づいて説明する。図１は本発明に係る第１及び第２の実施の形態のスピーカ用振動板の成り立ちを説明するための製造工程フロー図である。図２及び図３は前記製造工程フローの各加工状態を示す模式図である。図４は本発明に係るスピーカ用振動板の素材である木材の形状の加工段階を説明する模式図である。図５は本発明に係るスピーカ用振動板の木製シート又は貼り合わせシートに設けた略Ｖ字状の切り込み及び噛み合わせ掛止機構数例を示す図である。図６は本発明に係るスピーカ用振動板の木製シート又は貼り合わせシートを噛み合わせ掛止機構によって略ラッパ形状に掛止保持した状態を示す図である。
【００２４】
先ず、図４において、本発明のスピーカ用振動板３０又は４０の素材となる木材は、製造の準備段階として、例えば（ａ）に示されるように、木材の丸太６からロータリー方式により削り出し用刃７で円周方向から薄く剥がされて実際に振動板となる成形部分（破線の円形部分内）よりも大きめの適当な形状に切断されて（ｂ）のような大きな柾目の木製シート１０になる。例えば、口径８ｃｍ程度のダイナミック・コーン・スピーカの振動板では、一辺１２〜１４ｃｍ程度の正方形や矩形乃至直径１２ｃｍ程度の円形とする。
【００２５】
次に、製造段階に入って、前記木製シート１０又は図２の（ａ）の不織布又は和紙１３の貼り合わせ工程を経た貼り合わせシート１５に対して、図２の（ｂ）のように略Ｖ字状の切り込み１１及び該切り込みの縁部１１ａ、１１ｂ（斜線領域）同士が互いに重ねられて全体が略ラッパ形状に掛止保持されるための噛み合わせ掛止機構１４が設けられる。この噛み合わせ掛止機構１４は、例えば前記切り込みの縁部１１ａから延設する凸部１４ａと対向する他方の縁部１１ｂ近傍に設けられた切欠部１４ｂで構成され、前記凸部１４ａを前記切欠部１４ｂに挿入することにより、図６に示されるように全体が略ラッパ形状に掛止保持される。なお、上記略Ｖ字状の切り込み１１は図５の（ａ）、（ｂ）のような単純なＶ字状のみならず図５の（ｃ）のような鋸歯状や図５の（ｄ）のような波状であってもよい。要は両縁を重ね合わせると全体が略ラッパ状（コーン形状）になればよいのである。また、上記噛み合わせ掛止機構１４も上記凸部１４ａと切欠部１４ｂの組み合わせ以外に図５の（ｄ）のような互いに挟み合う形状の突起１９ａ、１９ｂでもよい。要は接着剤やクリップといった別部材を用いずに木製シート１０又は貼り合わせシート１５における成形部分（破線の円形部分内）以外の外周の余白部分を利用して掛止保持する機構であればよい。
【００２６】
次に、幾つかのプレス成形工程等を経て最終的に図７の概略図のような略ラッパ形状のダイナミック・コーン・スピーカのスピーカ用振動板３０又は４０となる（図３の（ｊ）の断面図も参照）。
【００２７】
図７に示される上記スピーカ用振動板３０又は４０の木目は、ボイスコイル用に切り抜かれた中心孔２５から半径方向（例えば、ｄａ〜ｄｈ方向）をみると、木目方向に沿うのはｄａ方向しか存在しなく、他方向は木目とある角度をもって交差している。したがって、殆どの方向において同一の音伝搬速度は存在しないことになり、定在波が発生しにくく共振ポイントが殆ど生じないので、分割振動が抑えられるのである。
【００２８】
また、上記スピーカ用振動板３０又は４０は木製であることに基づく優れた音響特性と美しい木目の仕上がりを備えるとともに選択された潤滑剤や熱硬化性樹脂、防湿剤の含浸及び一連のプレス加熱成形工程の工夫等により、しわや割れが無く、湿度による経時変化が小さく寿命の長いものとなっている。そして特筆すべきは、その製造工程は簡単でありながら非常に歩留まり良く、製造コストを抑えた量産性に優れたものとなっている。
【００２９】
ここで、本発明のスピーカ用振動板３０又は４０の素材に適する木材について考察すると、図１０の各種木材の有する内部損失係数と音伝搬速度（縦方向）についての関係を従来の材料であるアルミと紙と共に表したグラフ及び各種木材の密度、ヤング率、音速、内部損失係数（ｔａｎδ）を表した下記［表１］から判るように、概ね合板を（Ｇ点、Ｈ点、Ｉ点、Ｊ点）除く木材（無垢材）が適度な内部損失係数と高い音伝搬速度を有する優れた素材となり得ることが判る。特に、カバ（Ａ点）やブナ（Ｃ点）が最適であることが判る。
【００３０】
【表１】

【００３１】
なお、図１０中のＡ点はカバ（無垢材）であり、以下、Ｂ点；シナ（無垢材）、Ｃ点；ブナ（無垢材）、Ｄ点；オーク（無垢材）、Ｅ点；チェリー（無垢材）、Ｆ点；スプルース（無垢材）、Ｇ点；シナ合板（共芯）、Ｈ点；ラワン合板、Ｉ点；ＭＦＤ、Ｊ点；パーティクルボードである。
【００３２】
次に、本発明に係るスピーカ用振動板３０又は４０の製造方法を図１の（ａ）から（ｊ）までのフロー図及び図２、図３の対応する（ａ）から（ｊ）までの模式図に従って説明する。
【００３３】
先ず、請求項２に係る第１の実施の形態（Ａ）のスピーカ用振動板４０の製造工程は、図１に示されるように予め素材準備段階で（ｐ）木製シートの作成の後の（ａ）〜（ｊ）までの１０工程で構成され、（ａ）貼り合わせ、（ｂ）Ｖ字状切り込み及び噛み合わせ掛止機構の形成、（ｃ）潤滑剤含浸、（ｄ）仮成形の１次プレス、（ｅ）乾燥１、（ｆ）熱硬化性樹脂含浸、（ｇ）半乾燥、（ｈ）２次プレス、（ｉ）防湿剤塗布、（ｊ）中心孔・外形抜きの順に行われてスピーカ用振動板４０の完成となる。
【００３４】
上記各工程の詳細内容を以下順に説明する。
工程（ａ）・・・０．ｌｍｍ〜０．９ｍｍ厚（好ましくは０．３ｍｍ程度）の木製シート１０の一面側に、接着剤により略０．０２〜０．３０ｍｍ厚の不織布又は和紙１３を貼り合わせて貼り合わせシート１５を作成する。ここにいう不織布はカーボン材その他の合成樹脂からなる周知材料であり、貼り合わせた一面側が完成した振動板３０の背面側となる。上記木製シート１０の厚さは成形性と音響特性及びダイナミック・スピーカの口径を考慮した上でのスピーカ用振動板として適正な厚さである。
工程（ｂ）・・・貼り合わせシート１５に対して、中心部に頂点が至る略Ｖ字状の切り込み１１とその頂点近傍に小穴１２及び切り込み１１の縁部１１ａ、１１ｂ（斜線領域）同士が互いに重ねられて全体が略ラッパ形状に掛止保持されるための噛み合わせ掛止機構１４を設ける。前記切り込み１１は、貼り合わせシート１５の木目方向（矢印ｆ）に概ね沿って設ける。なお、上記小穴１２は略ラッパ形状に成形する際の中心部の割れを防止するためのものであり、直径数ミリの円形、楕円形、六角形等であって形状に制限はない。
工程（ｃ）・・・Ｖ字切り込みした前記貼り合わせシート１５が軟化するように、貼り合わせシート１５の中に浸透して水分を与え且つ水分を保持する作用のある潤滑剤１６の液中に５〜６０分浸し、十分に含浸させる。
【００３５】
これは後の１次プレス加熱成形を実施する時に割れを未然に防ぎ、歩留まり良く仮成形するためである。本発明者の研究によれば前記潤滑剤１６としては、単なる水若しくはアルカリ水溶液ではなく、糖類を溶解させた水溶液が適する。なお、上記潤滑剤１６を含ませる前に、貼り合わせシート１５を前記噛み合わせ掛止機構１４で略ラッパ形状に掛止保持しておいてもよい。
工程（ｄ）・・・ヒータ３３を各々備えた上型３１と下型３２の金型構成のプレス装置Ｐ１によって、前記潤滑剤１６を含浸させた貼り合わせシート１５を前記切り込み１１の両縁部１１ａ、１１ｂを互いに重ね合わせて前記噛み合わせ掛止機構１４の凸部１４ａと切欠部１４ｂを噛み合わせることによって略ラッパ状になるように保持した状態で１次プレス加熱成形（仮成形）する。ここで１次プレス加熱成形の設定条件は、プレス圧力が略１〜１０Ｋｇ、金型温度は上型３１が略８０〜１５０℃、下型３２が略１００〜２００℃、プレス時間が略２〜６０秒である。なお、上記噛み合わせ掛止機構１４によってプレス装置Ｐ１にセッティングする前から略ラッパ状に形状が保持されているため、セッティングの作業性が向上し、且つ１次プレス加熱成形（仮成形）の成形性の向上（しわや割れが少ない）が実現している。
工程（ｅ）・・・乾燥炉（５０〜６０℃）に略１０〜３０分間入れて完全乾燥を行なう。
工程（ｆ）・・・乾燥後の貼り合わせシート１５を熱硬化性樹脂１７液中に略３０分〜１８０分浸し、十分に含浸させる。上記熱硬化性樹脂１７としてはフェノール樹脂が適する。
工程（ｇ）・・・熱硬化性樹脂１７の含浸直後、後工程の２次プレスを実施すると、金型に熱硬化性樹脂１７が貼り付いてしまい、プレス後に貼り合わせシート１５を剥がす時に割れや引きちぎれが発生して歩留まりが極度に低下する。逆に完全に乾燥させると成形性が悪くなって割れやすくなる。これを防止するために、乾燥炉（５０℃〜６０℃）に略１〜１０分間入れて熱硬化性樹脂１７を半乾燥状態（指で触ってもべたつかない程度の所謂“指触乾燥状態”である。）にする。
工程（ｈ）・・・前記工程（ｄ）と同様の周知の構成のプレス装置Ｐ２によって、含浸させた熱硬化性樹脂１７が半乾燥状態の貼り合わせシート１５を再度プレス加熱成形する。ここで２次プレス加熱成形の設定条件は、プレス圧力が略２０〜４０Ｋｇ、金型温度は上型３４が略８０〜２００℃、下型３５が略１００〜２００℃、プレス時間が略１０〜１００秒である。成形後は揮発成分が蒸散して成形形状が略ラッパ状に安定した貼り合わせシート１５となる。なお、この時点で重ね合わせて貼着された前記切り込み１１の縁部１１ａ、１１ｂ（斜線領域）同士はその段差が殆ど判別できない程度に密着しており、音響特性に与える影響は殆ど無いものとなっている。
工程（ｉ）・・・２次プレス後の貼り合わせシート１５の表裏両面に筆による塗布若しくはジャブ漬けにより防湿剤１８を塗布する。この防湿剤１８としては例えば、ポリイソシアネートとポリエステルポリオールを混合したものを用いる。なお、塗布された上記防湿剤１８は自然乾燥又は乾燥炉で完全乾燥を行なう。
工程（ｊ）・・・防湿処理されたプレス加熱成形後の貼り合わせシート１５にボイスコイル用の中心孔２５と外形抜きが施されて所定の振動板形状に加工されてスピーカ用振動板４０が完成する。
【００３６】
上記完成した略ラッパ状のスピーカ用振動板４０は、従来のダイナミック・スピーカと同様にボイスコイル、ダンパー、エッジ、磁気回路、フレーム等と組み合わされてスピーカユニットに組み込まれる。
【００３７】
次に、上記本発明に係る第１の実施の形態のスピーカ用振動板４０の製造工程（Ａ）では、不織布又は和紙１３を貼り合わせる工程（ａ）を含んでいたが、前記不織布や和紙１３を木製シート１０の一面側に貼り合わせなくても、図１に示される請求項１に係る第２の実施の形態の（Ｂ）のフローの製造工程を経てなるスピーカ用振動板３０も実現可能である。即ち、工程（ａ）が無い木製シート１０のみでも工程（ｂ）のＶ字状切り込み及び噛み合わせ掛止機構の工程以降を同じくすれば木製振動板が製造できる。その製造方法は、前述の工程（ｂ）以下の説明における「貼り合わせシート１５」を「木製シート１０」と置き換えることで説明される。
【００３８】
尤も、厚さが０．１〜０．９ｍｍ程度の木製シート１０は取り扱い上非常に割れ易いので、予め工程（ａ）を施して不織布又は和紙１３で補強することが望ましいといえる。
【００３９】
本発明者の研究によれば、上記各実施の形態において、明確に従来の紙パルプ製の振動板やアルミ製の振動板に比べて再生音の解像度向上や歯切れ良い音の向上が得られるのは、縦方向伝搬速度が４．５〜６．０ｋｍ／秒、横方向伝搬速度が２．０〜４．５ｋｍ／秒の範囲の木材を選定した場合であった。
【００４０】
特に顕著に音響特性の向上が実感されるのは、縦方向伝搬速度が４．５〜６．０ｋｍ／秒、横方向伝搬速度が２．０〜２．５ｋｍ／秒の範囲で内部損失係数が０．０２〜０．０３の範囲の木材を選択して振動板に用いた場合であり、具体的にはカバ材（無垢）が最良であった。
【００４１】
勿論、本発明のスピーカ用振動板はカバ材のみならず、ブナ、オーク、チェリー、シナ等の他の材木を適用することもできることは言うまでもない。
【００４２】
【発明の効果】
上記のように本発明に係るスピーカ用振動板は１枚の木材を素材とし、従来の紙パルプ製振動板の製造過程に存在するような化学薬品での蒸解や木材繊維の叩解処理が加えられていないので音質劣化が発生しない。
【００４３】
さらに、従来の木製振動板のような柔軟化のためのボイル処理、物理的処理、化学的薬品が施されていないので音質劣化が発生しない。
【００４４】
プレス加熱成形時のしわや割れの発生が防止されて、仕上がりの良い均一なプレス加熱成形品となっており、変形や割れといった経時変化が少ない。
【００４５】
しかも軽くて丈夫なコーン振動板が製造可能になり、ウーハーからフルレンジスピーカまで全ての帯域に対応した振動板が製造できる。
【００４６】
また、噛み合わせ掛止機構によってプレス成形前から略ラッパ状に形状が保持されているため、セッティングの作業性が向上し、成形性の向上が実現して歩留まりが向上して、安価供給が実現できる。
【００４７】
本スピーカ用振動板がスピーカユニットに採用された際には、木製であるが故の自然な振動による生音に迫る再生音が経時変化なく出力される。
【００４８】
さらに、表面に自然の木目が表れているので、高級感のある外観体裁となる。
【図面の簡単な説明】
【図１】本発明に係る第１及び第２の実施の形態のスピーカ用振動板の成り立ちを説明するための製造工程フロー図である。
【図２】前記製造工程フロー図の各加工状態（前半）を示す模式図である。
【図３】前記製造工程フロー図の各加工状態（後半）を示す模式図である。
【図４】本発明に係るスピーカ用振動板の素材である木材の形状の加工段階を説明する模式図である。
【図５】本発明に係るスピーカ用振動板の木製シート又は貼り合わせシートに設けた略Ｖ字状の切り込み及び噛み合わせ掛止機構の例を示す図である。
【図６】本発明に係るスピーカ用振動板の木製シート又は貼り合わせシートを噛み合わせ掛止機構によって略ラッパ形状に掛止保持した状態を示す図である。
【図７】本発明に係る略ラッパ形状のダイナミック・コーン・スピーカのスピーカ用振動板の概略図である。
【図８】従来の木製振動板の製造手順を示す図である。
【図９】従来の木製振動板の製造手順を示す図である。
【図１０】各種木材の有する内部損失係数と音伝搬速度（縦方向）についての関係を従来の材料であるアルミと紙と共に表したグラフである。
【符号の説明】
６丸太
７削り出し用刃
１０木製シート
１１略Ｖ字状の切り込み
１１ａ、１１ｂ両縁部
１２小穴
１３不織布又は和紙
１４噛み合わせ掛止機構
１４ａ凸部
１４ｂ切欠部
１５貼り合わせシート
１６水分を与え且つ水分を保持する作用のある潤滑剤
１７熱硬化性樹脂
１８防湿剤
１９ａ、１９ｂ突起
２５中心孔
３０、４０スピーカ用振動板
３１、３４上型
３３ヒータ
３２、３５下型
Ｐ１、Ｐ２プレス装置[0001]
BACKGROUND OF THE INVENTION
The present invention belongs to the technical field of audio speakers, and particularly relates to a speaker diaphragm used for dynamic speakers.
[0002]
[Prior art]
Conventionally, most diaphragms of dynamic speakers are made of paper pulp, plastic, or metal such as aluminum. Since these conventional diaphragms are formed by pressing a uniform material, the sound propagation speed in the radial direction from the center is the same in all directions. Therefore, a standing wave always occurs and has a resonance point. This causes a problem that sound pressure frequency characteristics are deteriorated due to divided vibrations in a low frequency region, and a sense of reality is lost. Paper pulp and plastic diaphragms have a relatively large internal loss factor, but on the contrary, they are inferior in terms of rigidity (Young's modulus), and the sound propagation speed is low, so the resolution of the reproduced sound is somewhat unsatisfactory. Remain. On the other hand, although a metal diaphragm such as aluminum has a high sound wave propagation speed, the internal loss coefficient is small, so that the attenuation of amplitude is small and the division of reproduced sound is unclear (so-called sound sharpness is poor). .
[0003]
Instead of the existing diaphragms having the advantages and disadvantages as described above, it is desired to realize a wooden diaphragm as a diaphragm for a speaker that can reproduce a more natural sound.
[0004]
That is, the sound wave propagation speed of wood varies depending on the type, but is generally higher than that of paper pulp. Further, the propagation speed differs in the direction of the wood grain and the direction perpendicular thereto, and the propagation speed in the wood grain direction (referred to as the vertical direction) is fast and perpendicular to the grain The propagation velocity in the direction (referred to as the transverse direction) has an anisotropic propagation property that it is relatively slow. In addition, wood generally has an appropriate internal loss factor as a speaker diaphragm, and is light and strong (high rigidity).
[0005]
Therefore, a wooden diaphragm made of wood itself is unlikely to generate a standing wave and hardly has a resonance point. Therefore, divided vibration hardly occurs, and improvement of sound pressure frequency characteristics in a low frequency region is expected. Compared with a paper pulp diaphragm, the resolution of the reproduced sound can be improved and the sound can be improved crisply.
[0006]
Various proposals have already been made, for example, in the following publicly known literatures as methods for manufacturing the wooden diaphragm or the dynamic speaker using the wooden diaphragm or the wooden diaphragm.
[0007]
In the following [Patent Document 1], a flat plate made of WPC made by impregnating and hardening a plastic material such as polyester on a flat plate made of wood material is a flat plate diaphragm for a speaker excellent in characteristics such as dimensional stability, internal friction, and rigidity. The speaker used as is proposed.
[0008]
The following [Patent Document 2] has (a) an arc-shaped cutout portion 1a in the center from one piece of wood sheet 4 as in the manufacturing procedure shown in FIGS. 8 (a) and 8 (b). Then, the wood sheet 1 which is a substantially trumpet-shaped developed shape having a fan-shaped cutout portion 1b is cut out, and (b) both edges b1 and b2 of the fan-shaped cutout portion 1b of the wood sheet 1 are glued. A cone diaphragm 5 has been proposed which is formed in a trumpet shape by being overlapped and bonded to each other at an allowance portion 1c and then press-molded.
[0009]
Further, as in the manufacturing procedure shown in FIGS. 9A and 9B, a plurality of small pieces of wood 2a, 2b,... A cone diaphragm 2 formed and then press-molded has been proposed. Further, there has been proposed a cone diaphragm obtained by adding physical moisture resistance treatment or chemical moisture resistance treatment to the

cone diaphragms

1 and 2.
[0010]
In the following [Patent Document 3], a composite sheet composed of an ultrathin wood sheet sliced to 80 μm or less and a non-woven fabric made of an adhesive resin attached to the back surface thereof is softened with a softening agent. Thus, there has been proposed an acoustic diaphragm in which a plurality of sheets are stacked and further heated and pressed to form a conical shape.
[0011]
In the following [Patent Document 4], a flat timber sheet cut into a fan shape is boiled with high-temperature steam, hot water, or an alkaline solution having a pH of 10 or more to prevent cracking during molding, and then conical. A cone diaphragm formed by press molding has been proposed.
[0012]
In the following [Patent Document 5], a laminated sheet in which a thin non-woven fabric or Japanese paper is pasted on one side of one wooden sheet is prepared, and this is impregnated into a container containing a lubricant, and the impregnated laminated sheet There has been proposed a loudspeaker diaphragm that is press-heated and formed into a substantially trumpet shape.
[0013]
The following [Patent Document 6] describes a thin non-woven fabric or Japanese paper on one side of one wooden sheet in order to produce a wooden speaker diaphragm that does not cause wrinkles or cracks during press molding and has little change over time. There has been proposed a speaker diaphragm in which a bonded sheet with a carbon sheet attached is prepared, impregnated with a thermosetting resin, and then press-heat molded to form a substantially trumpet shape.
[0014]
[Patent Document 1]
JP-A-62-2224196
[Patent Document 2]
JP-A-1-288100
[Patent Document 3]
JP-A-5-83792
[Patent Document 4]
JP-A-6-178386
[Patent Document 5]
JP-A-10-304492
[Patent Document 6]
JP 2000-59883 A
[Problems to be solved by the invention]
The point of particular importance in the wooden speaker diaphragm is how to deal with the nature of wood, which is easily broken, and how to deal with poor formability and aging.
[0015]
In this respect, [Patent Document 1] is a wooden flat diaphragm, and although the characteristics and advantages of being a wooden are shown, there are problems in forming into a substantially trumpet shape (cone shape). No technical data is provided because it is flat.
[0016]
Further, in the manufacturing method as shown in FIGS. 8 and 9 of [Patent Document 2], the wood sheet 1 or the wood piece sheets 2a, 2b,. Or cracking during press molding, or because the wood sheets are bonded to each other with an adhesive, there is a problem that the adhesive part becomes an obstacle and desired acoustic characteristics cannot be obtained, and dimensional accuracy cannot be secured. .
[0017]
Further, the method of laminating a plurality of ultra-thin wood sheets of [Patent Document 3] has a difficulty in processing accuracy, and the adhesive layer increases and the weight of the diaphragm itself increases due to the weight of the adhesive. The desired acoustic characteristics cannot be obtained, and a large amount of adhesive adversely affects the sound pressure frequency characteristics, which is not preferable.
[0018]
In addition, as in [Patent Document 4], in the case of a manufacturing process including boil treatment with high-temperature steam or an alkaline solution having a pH of 10 or more before press molding, a constituent material called lignin in the wood is also removed. The original characteristics of the sound cannot be exhibited, and the sound quality will be adversely affected.
[0019]
Above all, the contents of the above [Patent Document 2], [Patent Document 3], and [Patent Document 4] have many defects such as cracks, cracks and wrinkles during production, and the yield in mass production is very high. It is getting worse and not commercialized.
[0020]
In addition, in [Patent Document 5] and [Patent Document 6], a thermosetting resin is used to impregnate a lubricant for extracting “tension” and “flexibility”, prevent wrinkles and cracks from occurring, and prevent change over time. The speaker diaphragm formed by press-heating after impregnation is superior to the above [Patent Document 1] to [Patent Document 4] in the manufacturing process for mass production, but still has sufficient moldability and molding. It is difficult to say that the establishment of the treatment has been achieved, and it is desired to further improve the formability and to realize a beautifully finished wooden diaphragm for practical use of the wooden diaphragm.
[0021]
The present invention has been made in view of the above circumstances, and provides a wooden speaker diaphragm that is effective in improving the acoustic characteristics of an audio speaker and is excellent in mass productivity.
[0022]
[Means for Solving the Problems]
In order to solve the above problems, the present invention
(1) In a speaker diaphragm formed by pressing one wooden sheet 10 into a substantially trumpet shape, a substantially V-shaped cut 11 having a vertex at the center of one wooden sheet 10. And the notch edges 11a and 11b are overlapped with each other and provided with a meshing latch mechanism 14 for latching and holding the whole in a substantially trumpet shape, and the notch 11 and the meshing latch mechanism 14 are provided. The wooden sheet 10 includes a lubricant 16 having an action of imparting moisture to the wooden sheet 10 and holding the moisture in the wooden sheet, and the wooden sheet 10 including the lubricant 16 includes the

edges

11a and 11b of the notch 11. They are overlapped with each other and are held in a substantially trumpet shape by the meshing latching mechanism 14 so as to be substantially trumpet shaped by primary press thermoforming. Molded, dried after the temporary molding, the thermosetting resin 17 is included after the drying, until the thermosetting resin 17 is half-dried state Drying is performed at a drying temperature of 50 ° C. to 60 ° C. for about 1 to 10 minutes. Semi-dried and secondarily press-molded with the thermosetting resin 17 in a semi-dried state, and after the second press-heated molding, a moisture-proofing agent 18 is applied to the wooden sheet 10 to which the moisture-proofing agent 18 is applied. Thus, a speaker diaphragm 30 is provided, which is formed by removing a central hole 25 and an outer shape for a voice coil and molding the voice coil into a predetermined shape.
(2) Bonding in which a thin nonwoven fabric or Japanese paper 13 is bonded to one surface of a single wooden sheet 10 in a speaker diaphragm formed by pressing a single wooden sheet 10 into a substantially trumpet shape. Engagement with the sheet 15 so that the substantially V-shaped notch 11 whose apex reaches the center and the

edges

11a and 11b of the notch 11 are overlapped with each other and the whole is hooked and held in a substantially trumpet shape. A latching mechanism 14 is provided, and a lubricant 16 having an action of imparting moisture to the laminated sheet 15 provided with the notch 11 and the engagement latching mechanism 14 to soften it and holding the moisture in the laminated sheet 15 is included. In addition, the laminating sheet 15 including the lubricant 16 is formed so that the

edges

11a and 11b of the notch 11 are overlapped with each other, and the meshing latching machine is used. 14 is temporarily molded into a substantially trumpet shape by primary press thermoforming in a state where the whole is hooked and held in a trumpet shape, dried after the temporary molding, and includes a thermosetting resin 17 after drying. The adhesive resin 17 is semi-dry Drying is performed at a drying temperature of 50 ° C. to 60 ° C. for about 1 to 10 minutes. Semi-dried and secondarily press-molded in the semi-dried state of the thermosetting resin 17. After the second press-heated molding, a moistureproof agent 18 is applied to the laminated sheet 15 to which the moistureproof agent 18 is applied. On the other hand, a speaker diaphragm 40 is provided, which is formed by removing a central hole 25 and an outer shape for a voice coil and forming the diaphragm into a predetermined size shape as a diaphragm.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of a speaker diaphragm according to the present invention will be described with reference to the drawings. FIG. 1 is a manufacturing process flow chart for explaining the formation of the speaker diaphragm according to the first and second embodiments of the present invention. 2 and 3 are schematic views showing each processing state of the manufacturing process flow. FIG. 4 is a schematic diagram for explaining the processing stage of the shape of the wood that is the material of the speaker diaphragm according to the present invention. FIG. 5 is a diagram showing a number of substantially V-shaped notching and engagement latching mechanisms provided on a wooden sheet or a laminated sheet of a speaker diaphragm according to the present invention. FIG. 6 is a view showing a state in which a wooden sheet or a laminated sheet of a speaker diaphragm according to the present invention is latched and held in a substantially trumpet shape by an interlocking latch mechanism.
[0024]
First, in FIG. 4, the wood used as the material for the speaker diaphragm 30 or 40 according to the present invention is cut out from a wood log 6 by a rotary method as shown in FIG. It is peeled thinly from the circumferential direction with the blade 7 and cut into an appropriate shape larger than the molded part (inside the broken-lined circular part) that actually becomes a diaphragm, and formed into a large square wooden sheet 10 as shown in (b). Become. For example, a dynamic cone speaker diaphragm having a diameter of about 8 cm is a square having a side of about 12 to 14 cm or a rectangle or a circle having a diameter of about 12 cm.
[0025]
Next, with respect to the laminated sheet 15 which has entered the manufacturing stage and has undergone the laminating process of the wooden sheet 10 or the nonwoven fabric or Japanese paper 13 of FIG. 2A, as shown in FIG. A character-shaped notch 11 and

edge portions

11a and 11b (hatched area) of the notch are overlapped with each other, and an engagement latching mechanism 14 is provided for latching and holding the whole in a substantially trumpet shape. The engagement latching mechanism 14 includes, for example, a notch 14b provided in the vicinity of the other edge 11b opposite to the protrusion 14a extending from the edge 11a of the notch, and the protrusion 14a is formed in the notch. By inserting into the part 14b, the whole is latched and held in a substantially trumpet shape as shown in FIG. The substantially V-shaped notch 11 is not only a simple V-shape as shown in FIGS. 5A and 5B, but also a saw-tooth shape as shown in FIG. 5C, or FIG. It may be wavy. In short, it is sufficient if the two edges are overlapped so that the whole becomes a substantially trumpet shape (cone shape). Further, the engagement latching mechanism 14 may be projections 19a and 19b having a shape sandwiched with each other as shown in FIG. 5D, in addition to the combination of the convex portion 14a and the notch portion 14b. In short, any mechanism can be used as long as it is latched and held using a blank portion on the outer periphery other than the molded portion (within the circular portion indicated by a broken line) in the wooden sheet 10 or the laminated sheet 15 without using another member such as an adhesive or a clip. .
[0026]
Next, after a number of press molding processes and the like, the speaker diaphragm 30 or 40 of a dynamic cone speaker having a substantially trumpet shape as shown in the schematic diagram of FIG. 7 is finally obtained (in FIG. 3 (j)). (See also cross-sectional view).
[0027]
When the speaker diaphragm 30 or 40 shown in FIG. 7 is seen from the center hole 25 cut out for the voice coil in the radial direction (for example, the da to dh directions), it is the da direction along the grain direction. However, the other direction intersects with the grain at a certain angle. Therefore, the same sound propagation speed does not exist in most directions, and standing waves are hardly generated and resonance points are hardly generated, so that divided vibration is suppressed.
[0028]
The speaker diaphragm 30 or 40 has excellent acoustic characteristics based on being made of wood and a beautiful wood finish, and is impregnated with a selected lubricant, thermosetting resin, moisture-proofing agent, and a series of press thermoforming. Due to the process, etc., there are no wrinkles or cracks, the change with time due to humidity is small, and the life is long. It should be noted that the manufacturing process is simple but has a very good yield and is excellent in mass productivity with reduced manufacturing costs.
[0029]
Here, considering wood suitable for the material of the speaker diaphragm 30 or 40 of the present invention, the relationship between the internal loss coefficient and the sound propagation speed (longitudinal direction) of various kinds of wood in FIG. As can be seen from the following [Table 1], which shows the density, Young's modulus, sound speed, internal loss coefficient (tan δ) of various woods and graphs represented with paper, the plywood (G point, H point, I point, J Point) It can be seen that the wood (solid material) except it can be an excellent material having an appropriate internal loss factor and a high sound propagation speed. In particular, it is found that hip (point A) and beech (point C) are optimal.
[0030]
[Table 1]

[0031]
In addition, A point in FIG. 10 is a hip (solid wood), and below, B point; China (solid wood), C point; Beech (solid wood), D point; Oak (solid wood), E point; Cherry (Solid wood), F point; spruce (solid wood), G point; China plywood (core), H point; Lauan plywood, I point; MFD, J point; particle board.
[0032]
Next, the manufacturing method of the speaker diaphragm 30 or 40 according to the present invention will be described with reference to the flow charts from (a) to (j) of FIG. 1 and the corresponding (a) to (j) of FIGS. It demonstrates according to a schematic diagram.
[0033]
First, as shown in FIG. 1, the manufacturing process of the speaker diaphragm 40 according to the first embodiment (A) according to claim 2 is performed in advance in the material preparation stage (p) after the production of the wooden sheet ( It consists of 10 steps from a) to (j), (a) bonding, (b) formation of V-shaped notch and engagement latching mechanism, (c) lubricant impregnation, (d) temporary molding 1 Next press, (e) Dry 1, (f) Thermosetting resin impregnation, (g) Semi-dry, (h) Secondary press, (i) Dampproofing agent application, (j) Center hole / outside shape removal Thus, the speaker diaphragm 40 is completed.
[0034]
The detailed contents of the above steps will be described in the following order.
Step (a) ... 0. A non-woven fabric or Japanese paper 13 having a thickness of approximately 0.02 to 0.30 mm is bonded to one side of a wooden sheet 10 having a thickness of 1 mm to 0.9 mm (preferably about 0.3 mm) with an adhesive to create a bonded sheet 15. To do. The non-woven fabric here is a well-known material made of a carbon material or other synthetic resin, and the bonded one surface side is the back surface side of the completed diaphragm 30. The thickness of the wooden sheet 10 is an appropriate thickness for a speaker diaphragm in consideration of moldability, acoustic characteristics, and the diameter of a dynamic speaker.
Step (b): A substantially V-shaped notch 11 having a vertex at the center and a small hole 12 and

edges

11a and 11b (hatched areas) of the notch 11 in the vicinity of the vertex of the laminated sheet 15 A meshing latching mechanism 14 is provided that is overlapped with each other and latched and held in a substantially trumpet shape as a whole. The cuts 11 are provided substantially along the grain direction (arrow f) of the bonded sheet 15. The small hole 12 is for preventing cracking of the central portion when being formed into a substantially trumpet shape, and has a circular shape, an elliptical shape, a hexagonal shape or the like with a diameter of several millimeters, and the shape is not limited.
Step (c): In the liquid of the lubricant 16 that has the function of permeating into the bonding sheet 15 to give moisture and holding moisture so that the V-cut laminated sheet 15 is softened. Soak for 5-60 minutes and fully impregnate.
[0035]
This is in order to prevent the cracking in the subsequent primary press heat forming and to perform temporary forming with a high yield. According to the study of the present inventors, the lubricant 16 is not simply water or an alkaline aqueous solution, but an aqueous solution in which saccharides are dissolved. Note that, before the lubricant 16 is included, the bonded sheet 15 may be latched and held in a substantially trumpet shape by the meshing latch mechanism 14.
Step (d): The laminated sheet 15 impregnated with the lubricant 16 is applied to both edges of the notch 11 by a press device P1 having a mold configuration of an upper die 31 and a lower die 32 each having a heater 33. 11a and 11b are overlapped with each other, and the convex portion 14a and the notch portion 14b of the engagement latching mechanism 14 are engaged with each other, and the primary press heat molding (temporary molding) is performed in a state of being held in a substantially trumpet shape. Here, the setting conditions of the primary press thermoforming are as follows: the press pressure is approximately 1 to 10 kg, the mold temperature is approximately 80 to 150 ° C. for the upper die 31, approximately 100 to 200 ° C. for the lower die 32, and the press time is approximately 2 to 2. 60 seconds. In addition, since the shape is maintained in a substantially trumpet shape before being set in the press device P1 by the meshing engagement mechanism 14, the workability of the setting is improved and the primary press heat forming (temporary forming) is formed. The improvement of property (less wrinkles and cracks) has been realized.
Step (e): Complete drying is carried out in a drying furnace (50-60 ° C.) for about 10-30 minutes.
Step (f): The laminated sheet 15 after drying is immersed in the thermosetting resin 17 liquid for approximately 30 minutes to 180 minutes and sufficiently impregnated. As the thermosetting resin 17, a phenol resin is suitable.
Step (g): Immediately after impregnation with the thermosetting resin 17, if the secondary press in the subsequent step is carried out, the thermosetting resin 17 is stuck to the mold, and cracks occur when the laminated sheet 15 is peeled off after pressing. As a result, tearing occurs and the yield decreases extremely. On the other hand, when it is completely dried, the moldability deteriorates and it becomes easy to crack. In order to prevent this, the thermosetting resin 17 is placed in a drying oven (50 ° C. to 60 ° C.) for approximately 1 to 10 minutes in a semi-dried state (so-called “finger-dried state” that is not sticky to the touch) ).
Step (h): The laminated sheet 15 in which the impregnated thermosetting resin 17 is semi-dried is press-heated again by the press device P2 having a known configuration similar to the step (d). Here, the setting conditions of the secondary press thermoforming are as follows: the press pressure is approximately 20 to 40 kg, the mold temperature is approximately 80 to 200 ° C. for the upper die 34, approximately 100 to 200 ° C. for the lower die 35, and the press time is approximately 10 to 10 ° C. 100 seconds. After molding, the volatile component is evaporated, and the bonded sheet 15 is formed in a stable shape in a substantially trumpet shape. It should be noted that the

edges

11a and 11b (shaded areas) of the cuts 11 that are overlapped and stuck at this point are in close contact with each other so that the level difference is hardly discernable, and there is almost no influence on the acoustic characteristics. It has become.
Step (i)... The moisture-proof agent 18 is applied to both the front and back surfaces of the bonded sheet 15 after the secondary press by brush application or jab immersion. As this moisture-proof agent 18, what mixed polyisocyanate and polyester polyol is used, for example. The applied moistureproof agent 18 is naturally dried or completely dried in a drying furnace.
Step (j): The voice coil center hole 25 and the outer shape of the laminated sheet 15 after press thermoforming that has been subjected to moisture-proofing are processed into a predetermined diaphragm shape, and the speaker diaphragm 40 is formed. Complete.
[0036]
The completed substantially trumpet-shaped speaker diaphragm 40 is combined with a voice coil, a damper, an edge, a magnetic circuit, a frame, and the like in the same manner as a conventional dynamic speaker and incorporated in a speaker unit.
[0037]
Next, the manufacturing process (A) of the speaker diaphragm 40 according to the first embodiment of the present invention includes the step (a) of bonding the nonwoven fabric or Japanese paper 13. The speaker diaphragm 30 can be realized through the manufacturing process of the flow (B) of the second embodiment according to claim 1 shown in FIG. It is. That is, a wooden diaphragm can be manufactured even if only the wooden sheet 10 without the step (a) is the same as the step of the V-shaped notch and engagement latching mechanism in the step (b). The manufacturing method will be described by substituting the “bonded sheet 15” with the “wood sheet 10” in the following description of the step (b).
[0038]
However, since the wooden sheet 10 having a thickness of about 0.1 to 0.9 mm is very easy to handle, it can be said that it is desirable to perform the step (a) in advance and reinforce it with a nonwoven fabric or Japanese paper 13.
[0039]
According to the inventor's research, in each of the above-described embodiments, it is possible to clearly improve the resolution of reproduced sound and improve sharp sound compared to conventional paper pulp diaphragms and aluminum diaphragms. Was the case of selecting wood having a vertical propagation speed of 4.5 to 6.0 km / second and a horizontal propagation speed of 2.0 to 4.5 km / second.
[0040]
The remarkable improvement in acoustic characteristics is particularly noticeable when the longitudinal propagation velocity is 4.5 to 6.0 km / sec and the lateral propagation velocity is 2.0 to 2.5 km / sec. This is the case where wood in the range of 0.02 to 0.03 is selected and used for the diaphragm, and specifically, the cover material (solid) is the best.
[0041]
Of course, it goes without saying that the speaker diaphragm of the present invention can be applied not only to birch but also other timbers such as beech, oak, cherry, and china.
[0042]
【The invention's effect】
As described above, the loudspeaker diaphragm according to the present invention is made of a single piece of wood, and is subjected to digestion with chemicals and beating of wood fibers that are present in the manufacturing process of conventional paper pulp diaphragms. Sound quality degradation does not occur.
[0043]
Furthermore, since the boil processing, physical processing, and chemical agents for softening as in the conventional wooden diaphragm are not performed, sound quality deterioration does not occur.
[0044]
Occurrence of wrinkles and cracks during press thermoforming is prevented, resulting in a uniform press thermoformed product with good finish, and there is little change over time such as deformation and cracking.
[0045]
Moreover, a light and durable cone diaphragm can be manufactured, and a diaphragm corresponding to all bands from a woofer to a full range speaker can be manufactured.
[0046]
In addition, the engagement latch mechanism keeps the shape in a roughly trumpet shape before press molding, improving setting workability, improving moldability, improving yield, and realizing low-cost supply. it can.
[0047]
When this speaker diaphragm is employed in a speaker unit, a reproduced sound approaching the raw sound due to natural vibration because it is made of wood is output without change over time.
[0048]
Furthermore, the natural wood grain appears on the surface, so it has a high-quality appearance.
[Brief description of the drawings]
FIG. 1 is a manufacturing process flow chart for explaining the formation of speaker diaphragms according to first and second embodiments of the present invention.
FIG. 2 is a schematic diagram showing each processing state (first half) of the manufacturing process flow chart.
FIG. 3 is a schematic diagram showing each processing state (second half) of the manufacturing process flow chart.
FIG. 4 is a schematic diagram for explaining a processing stage of a shape of wood that is a material of a speaker diaphragm according to the present invention.
FIG. 5 is a view showing an example of a substantially V-shaped notch and engagement latching mechanism provided on a wooden sheet or a laminated sheet of a speaker diaphragm according to the present invention.
FIG. 6 is a diagram showing a state in which a wooden sheet or a laminated sheet of a speaker diaphragm according to the present invention is latched and held in a substantially trumpet shape by an interlocking latch mechanism.
FIG. 7 is a schematic view of a speaker diaphragm of a substantially trumpet-shaped dynamic cone speaker according to the present invention.
FIG. 8 is a diagram showing a manufacturing procedure of a conventional wooden diaphragm.
FIG. 9 is a diagram showing a manufacturing procedure of a conventional wooden diaphragm.
FIG. 10 is a graph showing the relationship between the internal loss coefficient and sound propagation speed (longitudinal direction) of various kinds of wood together with aluminum and paper, which are conventional materials.
[Explanation of symbols]
6 logs
7 Cutting blade
10 Wooden sheet
11 V-shaped notch
11a, 11b both edges
12 Small hole
13 Nonwoven fabric or Japanese paper
14 Meshing latch mechanism
14a Convex
14b Notch
15 Bonding sheet
16 Lubricant that provides moisture and retains moisture
17 Thermosetting resin
18 Moisturizer
19a, 19b protrusion
25 Center hole
30, 40 Speaker diaphragm
31, 34 Upper mold
33 Heater
32, 35 Lower mold
P1, P2 press machine

Claims

In a speaker diaphragm formed by pressing a single wooden sheet into a substantially trumpet shape,
Engagement latch for a substantially V-shaped cut having a vertex at the center and the edges of the cut are overlapped with each other and held in a substantially trumpet shape on one wooden sheet A wooden sheet provided with a mechanism, and includes a lubricant having an action of softening the wooden sheet provided with the incision and meshing latching mechanism and retaining moisture in the wooden sheet; The sheet is temporarily formed into a substantially trumpet shape by primary press thermoforming in a state where the edges of the cuts are overlapped with each other and the whole is latched and held by the meshing latching mechanism. is dried after, the thermosetting resin is included after drying, the thermosetting resin is semi-dried is performed dried substantially 1 to 10 minutes at a drying temperature of 50 ° C. to 60 ° C. until a semi-dry state A secondary press thermoforming is performed in a semi-dry state of the thermosetting resin, a moistureproof agent is applied after the secondary press thermoforming, and a central hole for a voice coil is formed on the wood sheet coated with the moistureproof agent. And a speaker diaphragm, wherein the diaphragm is molded into a predetermined size and shape as a diaphragm.

In a speaker diaphragm formed by pressing a single wooden sheet into a substantially trumpet shape,
For a laminated sheet in which a thin non-woven fabric or Japanese paper is adhered to one side of a single wooden sheet, a substantially V-shaped incision with a vertex at the center and the edges of the incisions are overlapped with each other. A meshing latching mechanism is provided so that the whole is latched and held in a substantially trumpet shape, and moisture is given to the laminated sheet provided with the incision and meshing latching mechanism to soften and moisture is contained in the laminated sheet. The bonded sheet containing the lubricant containing the holding action is overlapped with each other at the edges of the cuts, and the entire latching mechanism is latched and held by the meshing latching mechanism. In a state of being temporarily molded into a substantially trumpet shape by primary press thermoforming, dried after temporary molding, and after drying, a thermosetting resin is contained, and the thermosetting resin is semi-dried At a drying temperature of 50 ° C. to 60 ° C. until the condition is performed dried substantially 1-10 minutes are semi-dried, the secondary press heat molding in a semi-dry state of the thermosetting resin, the secondary press heat molding After that, a moisture proofing agent is applied, and the laminated sheet coated with the moisture proofing agent is formed into a predetermined dimension shape as a diaphragm by performing a central hole punching for the voice coil and a contour cutting. A diaphragm for a speaker.