JP4173283B2 - Active acoustic device with panel member - Google Patents

Description

【００４７】
図１１−１４は２列目の高剛性パネル部材に関するものであり、図１５−２４は１列目の低剛性パネル部材に関するものであり、図２５−２８は３列目の中剛性パネル部材に関するものである。
【００４８】
グラフは全て、縦軸に音響出力パワー（ｄＢ／Ｗ）を、横軸に周波数をとっており、測定された音響出力パワーを周波数の関数として実際にプロットした点線で示している。グラフのほとんどは上側の真パワーライン調整も示している。前文で述べたように、この調整は平坦な直線に対して正規化を行なう機能を適用することによるもので、低周波数でのパワーの落ち込みというしばしば遭遇する影響を受けることなく、パネルの共振に際しての挙動の評価ができるようにしている。パワーの滑らかさが音質に大きく寄与することが分っている。実際のパワー出力のこのように正規化された値から、平均２乗偏差の逆数により滑らかさの評価を生成することは有益であり、棒グラフのほとんどはそのタイプである。
【００４９】
図１１−１４に関する高剛性パネル部材は、先の図７−９に用いられたものよりも実際には幾分か剛性が低いが、インボードのトランスデューサの、先に最適であるとされた配置、即ちコーナから３／７、４／９長、即ち０．４２−０．４４長の座標に対応する位置に単一のトランスデューサを配置するのが好ましいことを明示している。しかしながら、それぞれの端辺毎に、このような位置の間に、そしてこのような位置を越えて使用できる見込みのありそうな位置が実質的に拡がっており、実際には短辺及び長辺それぞれの中間領域の約１０％及び１５％以内、及び更には４分の１長位置の２８％及び３０％以内がそれに当たる。
【００５０】
別の間隔は０．０９までとしてはいるが、少なくとも殆どの部分につき、トランスデューサの端辺又は端辺付近の配置に対する試行位置は、インボードのトランスデューサ位置に対する０．４２という好適な座標値と端辺の中間点（０．５）との間の差に実質的に相当する間隔に基づいている。通常の試行位置は、従って０．０８、０．１７、０．２８、０．３３、０．４２、０．５０である。
【００５１】
図２３を参照すると、図示したグラフ及び棒グラフは、トランスデューサの取り付けについては最良且つ見込みがありそうな位置を示しており、局所的に設けられたクランピングについては、見込みの少ないトランスデューサ取り付け位置の場合にも性能をを改良する可能性がある位置を示していることは明らかである。
【００５２】
単一のトランスデューサを端辺又は端辺付近に配置することに関する限り、図１５及び２５が示すように、剛性がかなり低いものと中間のものという別の２種類のテスト用パネル部材も、パワーの滑らかさに関しては、インボードにおける好適な取付位置と対等の優位性を示している。しかしながら、剛性が低いパネル部材は、見込みのある位置範囲に近いものとして、コーナから測定して辺寸法の約４分の１から１０分の１より低い位置までの別の帯域を示している。興味深いことに、図３１Ａの平均２乗偏差棒グラフから分かるように、評価が効率即ちパワー出力の大きさに基づく場合、例えば真の出力パワープロットを通る中心線に基づいて平均２乗偏差をとるような場合には、上記帯域は斜めになって４分の１長位置が強調されるようになり、殆どの場合、インボードにおける好適な取付位置よりも好ましいものとなる。剛性が中程度のパネル部材は、剛性が高いパネル部材の特徴の方向に近づいており、インボードの好適取付座標位置の間に広がるように見込みのある取付位が存在することを示しているが、１０分の１位置周りにも見込みのある取付位置が存在することも示している。
【００５３】
真の出力パワープロットを吟味すれば、モード特性が重要な要素と考えられる音響再生の予想される質、即ち共振モードの励振の数及び均一度に対する影響という意味では、トランスデューサの標示される最良の端辺位置と実現可能な端辺位置の間には差があることが当業者には自明であろう。出力パワーの滑らかさ評価に基づき好適であると示される位置に関し、モード特性のような特性がより見込みがあるように見える場合には、無論、入力信号を上記の正規化の後に示されるものに向けて処理することは可能であり、特に、信号調整又は等化という形で低周波数を選択的に増幅することができる。このことは効率ベースで最適化された位置を使用して入手できるパワー（実際にそれを超える）を実現するが、より多くの入力パワーを使用しなければならないので、効率的といえないのは明らかである。
【００５４】
従って、先に示したように、低周波数のパワーを上げる他の方法が研究されており、それらは、バッフル配置及び／又は選択的に間隔を空けた局所的クランピング又は全端辺クランピングである。図１８Ａ、Ｂ、Ｃは、低剛性パネルよりも６０％多くの区域で周辺バッフルを施したもの、トランスデューサ位置には使わない３端辺全てに固定クランピングを施したもの、及びこのようなバッフルとクランピングの両方を施したたものにつき、低周波数出力が概ね有効に上がることを示している。このようなバッフルはモード特性を維持する傾向にあるが、特定の用途では必ずしも実行できるわけではない。したがって、クランピングをよく研究することは、低剛性のパネル部材について代替のトランスデューサ端辺位置という観点で価値があるように思われる。その結果は、図３１Ｂ、Ｃ、Ｄの棒グラフそれぞれから分かるように、効率に基づく評価は、トランスデューサ位置の端辺は長さに沿ってクランプしないで、平行な２端辺又は３端辺での全端辺クランピングをした場合と、図２９“Ｘ”に示すようなコーナ及び中間点７点の局所クランピングをした場合の両方共、４分の１長点を強調する傾向にあることを示した。しかし、図２９の“Ｘ”及び“Ｏ”の１３点クランピングの場合は、インボードの好適座標位置にはっきりと強調点が移った。パワー滑らかさに基づくクランピングしたパネル部材の評価は、図１９Ａ、２０Ｂ、２１Ｂ、２２の棒グラフに示すように、最良のトランスデューサ位置に関してはほぼ同じ結果を出しているが、次に好適な位置についてはかなり異なり、実際の出力パワーのプロットを調べることにより概ね確認される。
【００５５】
実際に、熟練者による検討に基づいた好適な結果とパワー出力の滑らかさに基づく評価との間には一般的に強い相関のあることが分かっている。このことは、いずれにしてもあまり違いはないが、音質ではなく効率を優先するという実際上の要因がなければ、このような評価がわずかにでも好ましいことを確認する方向にある。
【００５６】
局所化された端辺クランピングに対する別の適用は、見込みのないトランスデューサ端辺位置を改善することに関連があり、これについては、図２３Ａ、Ｂの棒グラフの図において対象としている左側ではなくて右側に示された部分を参照されたい。対象の事例は低剛性パネル部材に関するものであり、３つの端辺は全体をクランピングし、トランスデューサ手段が配置される端辺と同じ端辺に沿って局所化されたクランプを行い、７点にわたってクランピング位置を変化させたものである。両方の場合、励振器からより遠いコーナからの約４分の１長の位置では改善が見られたが、クランピング条件なしについては図２３Ｂの右側の棒グラフを参照されたい。図２３Ａに示すように、全端辺クランピングの場合は範囲がより大きい。
【００５７】
パワー効率に基づく評価とパワー滑らかさに基づく評価との間に不一致がある場合は、トランスデューサが取り付けられている端辺に対するコーナ部にクランピングを施したパネル部材は、コーナ部の動きを強制的にゼロにすることを心に留めておくことが大事である。つまり、振動活動が反ノードのピークに到達する前には、関係する共振モードに対し、半波長の距離までしかないはずである。コーナ部に近いトランスデューサ位置が優位であることがパワー滑らかさ評価によって示される場合は、関係する全ての共振モード波形と結びつくことにより、平滑さがその波形中に極めて小さい隆起となるものの、低パワー／効率となりかねないので用心して扱われるべきである。従って、対応するパワー／効率の評価を調べることが推奨される。実際に最良のものは、評価の２つの基本の間に実質的一致がある場合であることが多く、そうでなければ特定の用途に対してはある妥協が特別に当てはまる場合であり、評価目的に合わせて正規化無しでも有りでも有利であればどちらでも良いが、パワー／周波数グラフの熟練者による検討を考慮にいれることが望ましい。
【００５８】
高い剛性又は中程度の剛性を有する幾つかの調査したパネル部材については、最良のトランスデューサ端辺位置に関し計測結果に相当一貫性のある尺度が認められたが、他の見込みのある位置に関してはかなり差が認められた。更に低い剛性のパネル部材は見込みのあるトランスデューサ端辺位置に関しては、あまり決定的なことがないことがはっきりした。
【００５９】
この位置は、同一パネル部材の端辺に２個以上のトランスデューサ手段を配して使用する場合を考慮する際には更により明白になる。パネル部材の共振モードとの連結を強化する位置は、それら共振モードとパネル部材が本来持っている共振振動パターンとの避けられない組み合わせ相互作用の複雑さに付きまとわれ、パネル端辺だけに生じるこのような分布振動パターンにより合成されたものとなる。確立されたインボード領域におけるトランスデューサの好適な取付位置の座標軸に基づく単純な規則と比べて注目すべき変化がある。しかし、評価手順には、端辺配置されたトランスデューサ位置の良好な組み合わせを見つけるための有効なツールを使用できる。
【００６０】
図１３Ａ、１４Ａでは、前記の表の高剛性パネルについて、一つのトランスデューサ手段を長辺に沿って、０．４２の好適位置に対して約０．３８−０．４５の許容差範囲内の位置に配置している。第２のトランスデューサ手段は、最も近い短辺に沿って位置を変化させてあり、図１４Ａでは、０．４２好適位置を最も遠い位置とし、０．５８を中心として、共通のコーナから約４分の１、３分の１、３分の２長の他の位置と比べて周縁優位性を示している。興味深いことに、第２トランスデューサ手段を短いパネル端辺に沿う約０．５８好適位置に固定し、他のトランスデューサを長いパネル端辺に沿って位置を変化させると（図１３Ｂ、１４Ｂ参照）、最適位置及び次に最適な位置は長いパネル端辺に沿う約５分の１（０．１７）及び４分の１長位置になり、両方の位置ともにパワー滑らかさに関して開始位置（約０．４２）よりも良好となっている。これは明らかに反復法で更に適用することのできる手順ではあるが、しかしながら、パワー／効率評価と熟練者による検討の何れか又は両方を展開することが推奨され、特に、手順内で位置が収束しないか、又は良好な位置として示されるところが実際には希望よりも好ましくない（又は以前に手順内で好ましくなかった）場合において推奨される。
【００６１】
図１６Ａ、Ｂは、低剛性パネル部材で、長辺に対して好適な約０．４２トランスデューサ位置を適用し、第２のトランスデューサは最も近い短辺に沿って位置を変えた場合の研究の結果を示している。パワー滑らかさ増加には大した違いは見られず、最適な３箇所は直近の両コーナと最も近い０．４２優位位置であり、その他にも幾つかの組み合わせに対する概ね好適な位置がどれかの象限内にある。
【００６２】
中程度の剛性をもつパネル部材に対する同様の研究は、図２８Ａ、Ｂにある通り、隣接する象限において好ましい０．４２トランスデューサ位置（実際には０．５８）が好ましいことを強く示した。
はるかに低剛性のパネル部材の事例に戻るが、２つの効果が、十分に定義された最適の励振器位置／最適に近い励振器位置に寄与していることが分かる。１つは、最適化周波数範囲に対するパネルモードが、高剛性パネル部材の場合よりも高いことである。従って、パネル部材は連続体により近い近似体になり、出力パワーの滑らかさがトランスデューサ位置に依存する程度、特に第２トランスデューサ位置に依存する程度が弱まる。
もう１つの効果は、パネル部材の機械的インピーダンスが非常に低く、そのために、エネルギー伝達に関してトランスデューサ位置への依存がそれほど強くなくなることに関連する。関連するメカニズムについて以下に説明する。
【００６３】
図３０の１００、１０１を参照すると、パネル部材の機械的インピーダンス（Ｚｍ）が印加された点荷重のもとで生じる動きを決める。パネルのインピーダンスより非常に小さいか、それとほとんど等しいような機械的インピーダンスを持つ物体がパネル部材に取り付けられている場合には、その物体が取り付けられた位置ではパネル運動に強力な偏が生じる。可動コイル型の励振用トランスデューサをパネルに取り付けると、パネルを接地質量体（トランスデューサの磁石カップ、１０２参照）にばね（ボイスコイルサスペンション、１０２参照）を介して接続するのと同じになる。このようなばねのインピーダンスがパネルインピーダンスにあまりにも近ければ、トランスデューサ位置でのパネル運動をある程度規定することになる。トランスデューサ位置の点運動を全体的に定めるこのばねの限界点では、入力パワーの励振器位置への依存はないことになる。実際には、ばねインピーダンスのパネルインピーダンスに対する割合は、最適トランスデューサ位置に深く影響するので、結果は最良の／最良に近いトランスデューサ位置にとってもはやそれほど明白ではない。
【００６４】
機械的インピーダンスは、パネル端辺部ではたの部分よりも相当に低いので、この低い機械的インピーダンスは、インボード領域にトランスデューサが取り付けられる場合よりも端辺部にトランスデューサが取り付けられる場合の方が大きな影響を及ぼし、これはトランスデューサ、ボイスコイルサスペンションがより大きな影響力を有することを意味する。特に、前記の表の低剛性パネル部材では、
パネル本体の機械インピーダンスは、
Ｚｍｂｏｄｙ＝２．７Ｎｓｍ^-1である。
パネル端辺での機械インピーダンスは約Ｚｍｂｏｄｙの半分、即ち、
Ｚｍｅｄｇｅ＝１．３Ｎｓｍ^-1である。
使用するトランスデューサのボイスコイルサスペンションのコンプライアンスは、
Ｃｍｓ＝０．５２×１０^-3ｍＮ^-1である。
【００６５】
共振モード周波数それぞれにおける機械的インピーダンスは、平均インピーダンスＺｍｅｄｇｅよりも低い程度になるはずである。従って、それ以下で励振器がパネル部材に強い影響を及ぼす周波数を推定することが可能であり、例えば、ボイスコイルサスペンションのインピーダンスがパネル縁辺での平均インピーダンスの約５分の１となるところがそうである。従って、

であり、１２００Ｈｚの推定値を与え、これより下ではトランスデューサ及びパネルは意図的に連結されるが、それは最適化の周波数範囲内である。
【００６６】
トランスデューサとこのような低機械インピーダンスを有するパネル部材を、１つの連結されたシステムとして考えると、トランスデューサはパネル部材のインピーダンスを部分的に規定し、出力パワーの滑らかさのトランスデューサ位置への依存度が低くなる。
高剛性パネルにつきこのような分析を繰り返すことにより、１３０Ｈｚという対応する周波数が得られるが、これは最適化周波数範囲を外れている。
【図面の簡単な説明】
【図１】 本出願人による他のＰＣＴ出願に概括的に説明しているトランスデューサを取り付けた分布モード音響パネルを示す図である。
【図２】 音響パネルの周縁又は端辺を励振する４つの異なる方法を示す略図である。
【図３】 図２に示す作用を実行するため、音響パネルの縁部にトランスデューサをどのように配置できるかを示す図である。
【図３Ａ】 図３のパネルが透明パネルとなっているものを示す。
【図４】 破線で示す図１のインボード配置のトランスデューサに対応する、トランスデューサにとって好ましい４箇所の周縁位置を示す略図である。
【図５】 もう１つの好適なインボード駆動位置に対応する、同じく４つの好ましい位置と、相補的又は仮想のインボード駆動位置に対応する好ましい一対の位置を示す図である。
【図６】 このような好ましい位置にある任意の対及び全４個の駆動トランスデューサがテスト用にどのように接続されたかを示す図である。
【図７】 好適な対になった縁部駆動トランスデューサ位置が少ない場合に可能なものを示す図である。
【図８】 コーナ駆動位置とインボード好適駆動位置にある有用な質量体取り付けとを示す図である。
【図９】 ４箇所の通常は好ましくないとされる縁部駆動トランスデューサ位置を、多くの縁部質量体取り付け又はクランピング位置と共に示す図である。
【図９Ａ】 テスト用質量体と駆動トランスデューサがどのようにパネルと関連しているかを示す図である。
【図１０】 駆動トランスデューサ、クランプ終端、弾性サスペンション／取り付けに対する周縁位置内の障害物のないインボード区域を示す図である。
【図１１Ａ】 剛性が極めて高い実質的に矩形のパネル部材で、単一のトランスデューサが長い辺に沿って配置されている場合に関する、出力パワー／周波数の関係を示すグラフである。
【図１１Ｂ】 剛性が極めて高い実質的に矩形のパネル部材で、単一のトランスデューサが短い辺に沿って配置されている場合に関する、出力パワー／周波数の関係を示すグラフである。
【図１２Ａ】 出力パワーの滑らかさの計測値を示す関連棒グラフである。
【図１２Ｂ】 出力パワーの滑らかさの計測値を示す関連棒グラフである。
【図１３Ａ】 ２個のトランスデューサを配し、１個の位置を短辺又は長辺の上で動かした場合の、出力パワー／周波数の関係を示すグラフである。
【図１３Ｂ】 ２個のトランスデューサを配し、１個の位置を短辺又は長辺の上で動かした場合の、出力パワー／周波数の関係を示すグラフである。
【図１４Ａ】 出力パワーの滑らかさの測定値を示す関連棒グラフである。
【図１４Ｂ】 出力パワーの滑らかさの測定値を示す関連棒グラフである。
【図１５Ａ】 剛性がかなり低いパネル部材で、単一のトランスデューサが長辺に沿って配置されている場合についての、出力パワー／周波数の関係を示すグラフである。
【図１５Ｂ】 剛性がかなり低いパネル部材で単一のトランスデューサが長辺に沿って配置されている場合についての、パワー滑らかさ棒グラフである。
【図１６Ａ】 第２トランスデューサが短辺に沿って配置されている場合についての、出力パワー／周波数の関係を示すグラフである。
【図１６Ｂ】 第２トランスデューサが短辺に沿って配置されている場合についての、パワー滑らかさ棒グラフである。
【図１７】 剛性の低いパネル部材で、トランスデューサが好適にインボードにある場合と辺にある場合にパワー出力を比較したグラフである。
【図１８Ａ】 バフリングの効果を示すグラフである。
【図１８Ｂ】 ３端辺クランピングの効果を示すグラフである。
【図１８Ｃ】 バフリングの効果、３端辺クランピングの効果、の両方の効果を示すグラフである。
【図１９Ａ】 剛性の低いパネル部材で、３つの端辺に沿ってクランプされ、トランスデューサが第４辺にある場合の、出力／周波数の関係を示すグラフである。
【図１９Ｂ】 剛性の低いパネル部材で、３つの端辺に沿ってクランプされ、トランスデューサが第４辺にある場合の、パワー滑らかさ棒グラフである。
【図２０Ａ】 剛性の低いパネル部材で、平行な２つの端辺上でクランプされ、トランスデューサが別の辺にある場合の、出力／周波数の関係を示すグラフである。
【図２０Ｂ】 剛性の低いパネル部材で、平行な２つの端辺上でクランプされ、トランスデューサが別の辺にある場合の、関連パワー滑らかさ棒グラフである。
【図２１Ａ】 剛性の低いパネル部材で、コーナ／端辺中間で局所的にクランプされ、トランスデューサが別の長辺にある場合の、出力／周波数の関係を示すグラフである。
【図２１Ｂ】 剛性の低いパネル部材で、コーナ／端辺中間で局所的にクランプされ、トランスデューサが別の長辺にある場合の、出力／周波数の関係を示すグラフである。
【図２２】 剛性の低いパネル部材で、局所的クランピングが更に、別のコーナ／中間点クランピングの間に施されている場合のパワー滑らかさ棒グラフである。
【図２３Ａ】 剛性の低いパネル部材で、３端辺が７点でクランプされ、もう１箇所の局所クランプの位置はトランスデューサ手段が好ましくない位置にある別の辺に沿ってある場合の、正規化なしのパワー評価を示す棒グラフである。
【図２３Ｂ】 剛性の低いパネル部材で、全端辺クランプなしで、他の１箇所の局所クランプの位置はトランスデューサ手段が好ましくない位置にある別の辺に沿ってある場合の、正規化なしのパワー評価を示す棒グラフである。
【図２４Ａ】 ３端辺がクランプされた事例で正規化をして評価されたものについての、パワー出力／周波数の関係を示すグラフである。
【図２４Ｂ】 ３端辺がクランプされた事例で正規化をして評価されたものについての、関連パワー滑らかさ棒グラフである。
【図２５Ａ】 剛性が中程度のパネル部材で、単一のトランスデューサが長辺に沿って配置され、正規化が行なわれた場合のパワー出力／周波数の関係を示すグラフである。
【図２５Ｂ】 剛性が中程度のパネル部材で、単一のトランスデューサが長辺に沿って配置され、正規化が行なわれた場合の関連パワー滑らかさ棒グラフである。
【図２６Ａ】 剛性が中程度のパネル部材で、７点で局所的にクランプされ、正規化無しで評価された場合についての出力／周波数の関係を示すグラフである。
【図２６Ｂ】 剛性が中程度のパネル部材で、７点で局所的にクランプされ、正規化無しで評価された場合についてのパワー評価棒グラフである。
【図２７Ａ】 図２６Ａと同じであるが、パワー滑らかさ評価につき正規化が行なわれた場合を示すグラフである。
【図２７Ｂ】 図２６Ｂと同じであるが、パワー滑らかさ評価につき正規化が行なわれた場合を示すグラフである。
【図２８Ａ】 剛性が中程度のパネル部材で、第２トランスデューサが短辺に沿って配置されている場合についてのパワー出力グラフである。
【図２８Ｂ】 剛性が中程度のパネル部材で、第２トランスデューサが短辺に沿って配置されている場合についてのパワー滑らかさ棒グラフである。
【図２９】 上記に適用された７点及び１３点の局所的クランピングを示す図である。
【図３０】 トランスデューサ内コンプライアンスの影響力を説明するのに有効な概略図である。
【図３１Ａ】 剛性が低いパネル部材について、種々の端辺条件に対するパワー効率を示す棒グラフである。
【図３１Ｂ】 剛性が低いパネル部材について、種々の端辺条件に対するパワー効率を示す棒グラフである。
【図３１Ｃ】 剛性が低いパネル部材について、種々の端辺条件に対するパワー効率を示す棒グラフである。
【図３１Ｄ】 剛性が低いパネル部材について、種々の端辺条件に対するパワー効率を示す棒グラフである。
【図３１Ｅ】 剛性が低いパネル部材について、種々の端辺条件に対するパワー効率を示す棒グラフである。[0001]
(Technical field to which the invention belongs)
The present invention relates to an active acoustic device, more particularly to a panel member in which the acoustic action or performance is dependent on the resonant mode of bending wave action of the panel member and the advantageous distribution of surface vibrations associated therewith, It relates to a method of making or improving such an active acoustic device.
[0002]
It is convenient to use the term “distributed mode” for acoustic equipment including acoustic radiators or loudspeakers, and unless the context allows, the term “panel shape” refers to the distribution mode of the panel member. It is convenient to mean an action.
[0003]
In a panel-shaped loudspeaker, or as a panel-shaped loudspeaker, such a panel member operates as a distributed mode acoustic radiator depending on the bending wave action caused by the input means imparting mechanical motion to the panel member, and as a result Excitation of the resonant mode of bending wave action occurs, which couples with the surrounding fluid, usually air, to generate surface vibrations for acoustic output. Introductory teaching on such acoustic radiators (among a broader class of active or passive distributed mode acoustic devices) is given in Applicant's international patent application WO 97/09842, Pending patent applications contain various useful additions and improvements.
[0004]
(Background of the Invention)
Up to now, the position of the transducer is at least for a panel that is substantially isotropic with respect to bending stiffness and that has a substantially constant axial anisotropy with respect to bending stiffness. Drastically Inside panel member Sent to It has been considered that the position toward the center but deviating from the center is a feasible and optimal position. The above-mentioned WO97 / 09842 includes such an inboard including an alternative example. In the area Transducer Mounting Specific guidelines for optimal proportional coordinates for position are disclosed, as well as selection for separate specific coordinate combinations when using two or more transducers.
[0005]
Various advantageous applications specific to the panel shape of an acoustic device have been envisaged, including providing an acoustically non-intrusive face sheet or layer. For example, it may be visually inconspicuous and physically integrated or incorporated into a trim or exterior article. Furthermore, functional combinations with other purposes such as displays including pictures, posters, writing / erasing boards, projection screens, etc. are also conceivable. Inboard Attached to the area Many applications are sufficient if the transducer can be effectively hidden from view. However, Even if it is possible to make the transducer invisible, There are potential and practical applications where it is useful to leave a large, especially central panel area, unobstructed by the transducer. For example, for applications in video or other fluoroscopic displays, seek translucent panel members and even transparent panel members. But It's not worth it for the inboard arrangement of such transducers Even as It would be very attractive if the panel-shaped acoustic device could be made unobstructed by the wide central area.
[0006]
(Summary of Invention)
According to one device aspect of the present invention, the transducer means is provided at the peripheral position, and as a result of the arrangement, the distribution and the distribution of the resonance mode vibration exhibit an acoustically satisfactory effect resonance mode Type A panel-shaped acoustic apparatus including an acoustic panel member is provided. The presence of such an appropriate peripheral position is useful herein for the careful selection or improvement of one or more such position settings. Is made About the transducer means preferable Established as a position. This careful selection is expediently related to sufficiently transmitting the energy of vibration to the panel member by evaluating the parameters of the acoustic output from the target panel member when excited at the peripheral position or peripheral position. It is beneficial to study acoustic radiators or loudspeakers, or a selection will be made as a result of the study. at least ,this The best results apply to microphones.
[0007]
From the relevant background teachings at the time of the present invention, the possibility of utilizing such optimal perimeter positioning is at least unexpected. In fact, the main closest prior art cited against WO 97/09842 is the starting point for its invention and revelatory teaching, ie from WO 92/03024, in particular Taught in WO 92/03024 Corner section In Progress has begun in deviating from excitation. As a result of such progress, if the acoustic performance that can achieve the distributed resonance mode bending wave action is required, of Although it has become possible to understand that high vibration activity occurs at the corners, it is also generally a factor for the edge of the panel. At least intuitively, And, Somewhat off-center and biased but still inboard correctly In the area Transducer Mounting position By determining Strongly supported by actual success Is that However, this high vibration action A strong combined action with the panel periphery, which is obvious, but the mounting position is Limited Stuff , Therefore, the utilization effect of the entire panel member is reduced, and due to this combined effect, conventionally, Edge Part Excitation Was considered infeasible .
[0008]
Of the present invention Apply With regard to, a suitable acoustic panel member or at least a region thereof may be transparent or translucent. A typical panel member is generally polygonal and is often substantially rectangular. The plurality of transducer means are at or near separate edges, at least for a substantially rectangular panel member. these Transducer or transducer Each of May be any of piezoelectric, electrostatic, or electromechanical. these Transducer or transducer Each of Bend the panel edges laterally and / or across the panel corners for the purpose of sending a dense wave to the panel edges and / or for the purpose of sending lateral bending waves along the panel edges. Torsion and / or to create a linear deflection in the local area of the panel.
[0009]
The evaluation of the acoustic output from the panel member is based on the power output amount, that is, the conversion efficiency of the input mechanical vibration (automatically generated electric drive) into the acoustic output, and the power as a measure of the uniformity of excitation in the resonance mode of bending wave action. Relevant criteria for sound output, including examination of power output with respect to the frequency of the excited resonant mode, including smoothness of output, number and frequency distribution or spread, each of which is a useful guide Such an assessment of the feasibility of the position of the transducer means constitutes aspects relating to the method of the invention independently and in combination.
[0010]
As an aid to at least evaluating the smoothness of the power output, this specification proposes to use a method based on the mean square deviation from a certain reference. Use reciprocal of mean square deviation By Directly positive values and / or formulas so Of evaluation for Represents smoothness be able to There is an advantage. Appropriate criteria are individual for each case envisaged, e.g. based on an average, e.g. graphed by a smooth line across the actual measured power output for the frequency range of interest. . The fact that the reference has a normalized standard format and that the measured sound power output is adjusted to fit that standard format is very useful for mean square deviation evaluation. The standard format is a straight graph line, preferably a flat line corresponding to a certain fixed reference value, resonance Mode and resonance It is further desirable for the same line or value to be naturally found to be applied to the distributed mode panel member at the higher frequency where the mode action is more or the densest.
[0011]
In this context, a substantially constant standard Against Normalize like this Required function All can be applied to the input signal to improve the lower frequency sound output Function for Base of It is also effective as That should be noted. Feasible distributed mode panel members, as such, and with a favorable aspect ratio and bending stiffness as in the above-mentioned Applicant's application, the resonance mode and mode-like action are less dense Such a frequency distribution is often beneficial for acoustic effects in such a low frequency range, as it naturally has acoustic power output characteristics for frequencies that tend to decay toward and past low frequencies. As such, it may be useful to equalize the input signal as such. This low acoustic power output at low frequencies is related to the free-end vibration of such panel members, and inevitably the greater the loss of low-frequency power, the more effectively a short circuit around the edges of free adjacent panels. More parts, including As acoustic Imperfectly radiated , And / or tend to be dissipated. As expected, these low frequency power loss effects are due to the transducer being placed at or near the edge. Panel material And / or for panel members that are less stiff than panel members that utilize in-board transducer positions. However, and independent of the equalization of the input signal, these effects are sufficiently mitigated by attaching the panel member by surrounding the edges of the panel member with baffles and / or clamping. Indeed, spaced local edge clamps can have a selective beneficial effect that is useful for frequencies where the wavelength is longer than the local edge clamp spacing.
[0012]
Interestingly, for certain panel members that are extremely stiff, the position of the transducer at the perimeter that can be implemented is favored by applying the teachings and techniques as specified in the above patent application. Standard inboard for transducer means Mounting position Against Have a correlation Edge Includes location. When using a pair of transducer means In First priority position But , With respect to the transducer arrangement at the periphery, said correlation corresponding to a wider area conceptually included Relationship It was found by. Corresponding to Cartesian or Cartesian coordinates for substantially rectangular panel members To obtain the correlation. , In this case, The first priority position is , Diagonal transducer means Against Opposite side It is in In the quadrant To be placed . However, this is particularly relevant for high stiffness / high Q panel members, high (However , Above This is not always the case, even with lower (rigid) panels, and more specifically related to some or adjacent quadrants as shown below To state Prospect Actuation with Please refer to.
[0013]
For elliptical panel members, the correlation Relationship /Correspondence Relationship The inboard Territory By hyperbolic resonance mode relationship line extending in the end direction through the position. There are many other things that are considered less feasible but feasible, but placing the transducer means at a pair of edge positions may include in the vicinity of or including the corner position of the panel member. region Suitable transducer Mounting Found by research based on rotating orthogonal vector around position. In another aspect of the invention relating to corner or near-corner excitation, a substantially known inboard In the area Appropriately at the optimal or suitable drive position Do mass body installation or Or doing clamping, where , in this way Mass body attached The optimal drive position effectively acts as a “virtual” source of flexural wave vibration within the member to a certain effective range. The latter is Because the mass body is attached, What avoids central intrusion What is There is no corner In Certainly there is a close relationship with good peripheral excitation.
[0014]
Panel members with different stiffnesses, especially very high stiffness panel Very low panel In addition, in each case, the normal substantially rectangular shape was used, and the aspect ratio and axial bending stiffness were generally as in WO97 / 09842.
[0015]
For panel members with higher rigidity Leave ,The long side as well as Along the short side The Single transducer The Arrangement If you want Smooth power output Concerning Evaluation To do As expected for the best position of a single transducer means The peak shape of the sound output occurs in the The above preferred coordinate position was generally confirmed. However, To supplement ,The long side Is better , Each side Midpoint Coordinate position and this coordinate position Past At the transducer position between each corner up to about 1/3 length Leave Within about 15% of peak Indicates the smoothness of Furthermore, it is within about 30% to the position of at least a quarter length Indicates the smoothness of , Promising success Smoothness measurement of Distribution Indicated . For short sides, the distribution of smoothness measurements is within about 10% between coordinate positions. Yes It was within about 25% at the quarter length position. The short side actually showed a better power smoothness measurement than the long side showed from the quarter long position to within about a tenth of the corner length.
[0016]
The combination of two transducers is also the same as one transducer when one is arranged on the long side and one on the short side. Quadrant Adjacent quadrant When Has been studied. One transducer for a single transducer When research was conducted We placed it at the best position along the other side, and changed the position of the other transducer along the other end. Inboard when moving along the short side region Per one of a plurality of positions according to the coordinates of the preferred transducer position of Mentioned above The superiority is confirmed by the best smoothness measurement at about 6/10 length. The third quarter length is close to a good position, and the quarter and third length positions are slightly inferior but good. Furthermore, the corner Part Most of the locations other than about one-tenth from the same quadrant In Suitable inboard When area placement is performed Coordinates In contrast to ,Better Or As good as Or , To the same extent Close to good Or Or not so bad. When changing along the long side, the transducer on the short side is in a position close to the desired 6 / 10th, which is preferred for a combination of transducer positions in adjacent quadrants. The result was that it was actually marked and just below one-fifth was best, slightly better than the 0.42 position at the one-third long position and slightly worse at the one-tenth long position. The quarter length position is , Actually, it is almost the same as the position of the quadrant adjacent to the coordinates of the intermediate length position and the preferred inboard position. Obviously, repeating these procedures repeatedly will reveal more favorable combinations.
[0017]
Based on power output smoothness And Panel member with lower rigidity Went about Study the periphery In Transducer Occurrence of peak when Still inboard Arrangement of Case However, in the sense of the mode distribution actually achieved, the position along the side is generally less important. Show. This can be explained by the interaction between low panel stiffness and compliance within the transducer itself used.
Panel resonant mode distribution But Influenced by transducer position The It is clear that this is due to the change, at least to some extent. In the case of a panel having a higher rigidity, such an effect can be effectively avoided. However, it is clear that such intra-transducer compliance and possible interaction with panel stiffness / elasticity is another factor to consider, including effective utilization.
[0018]
Research on panel members with extremely high and fairly low stiffness, whether the importance of transducer position is greater or lesser, One transducer Or To Various examples of the use of peripheral excitation become clear, including whether the interaction with the compliance in the transducer is large or small. Thus, it is also appropriate to consider moderately rigid panel members.
[0019]
For panel members with medium rigidity, as expected, panel members with very low rigidity As the difference between , The edge clamping increases the acoustic power output, the power increases significantly for the mid-range frequency mode, and the low frequency mode Mode characteristics Or the peak is stronger Become Can Be mentioned . For the characteristics of panel members with higher rigidity When approaching Trend As The inboard Optimal in the area Transducer Mounting position Corresponding to Coordinate axis Upper edge position But, Transducer position Is strongly preferred as the best and only one , Also, Through the midpoint Position But probably about a tenth from the corner Even in the position of Promising possibility Ah The At the periphery Two Transducer means When placing About the inboard In the area Transducer Optimal for Coordinates related to position axis Is gaining attention, and at half-length or two-thirds long positions, the degree of goodness is inferior but may be realized range Is seen, and is equivalent at the position associated with the coordinates of the same quadrant and the two-thirds long position.
[0020]
Differences in panel member material parameters that exceed the basic ability to withstand bending wave effects are important in determining the peripheral transducer position, and using two or more such transducer positions, the present application It is clear that a highly independent solution is generated that requires the experimental evaluation now possible with the teachings of.
[0021]
Furthermore, at least, if not limited to the substantially rectangular panel members that have been tested, most, if not all, positions near or near the edges that are not likely for the transducer means. Also about ,local The mass body Alternatively, clamping at one or more selected peripheral positions of the panel member of interest can provide a significant improvement (with respect to bending wave dependent resonance mode distribution and excitation to the acoustic response of the member). Aspects of the invention thus include associating the drive means position with another useful mass attachment or clamping position on the periphery of the panel member.
[0022]
With regard to the use of more than one transducer means, it may not be practical to investigate thoroughly the combination of peripheral positions, but wherever the best for the second transducer and the peripheral position of a given first transducer. Methods for finding other possible peripheral positions are taught. Indeed, further edge transducer positions can be examined and evaluated in accordance with the teachings of the present application. In addition, using local peripheral damping to improve performance, for a given transducer peripheral position, will enhance the contribution of certain resonant modes to a certain extent and number using the teachings of this application? It is possible to investigate and evaluate whether to reduce, otherwise systematically interfere with other resonance modes, or mainly increase the output power.
[0023]
The lowest resonance mode is , Any panel member Also in Its longest Inherent The length of the axis is related, so the long side of the substantially rectangular panel member is a considerable extent as the position of the transducer means Always The fact that it is preferred It is generally useful to consider It is also generally considered worthwhile to take into account wherever possible where the best operation is in the case of a single transducer means. Transducer means Another To enhance certain resonance modes even when it is recommended or intended to be used for , Whether to intentionally cause interference with other resonance modes, or whether to increase the output power mainly When thinking ,this thing It makes sense to consider .
[0024]
In addition, as a general matter in this regard, the target operating frequency range depends on the transducer means. for of Mounting It should be part of the location assessment and will have a major impact on the best and possible such location, ie the range above and below 500 Hz will also be different. I can say that. Another influencing factor is the presence of adjacent surfaces, eg, adjacent surfaces that are spaced apart from the panel members to affect acoustic performance.
[0025]
Mentioned above Adjacent to or adjacent to an edge Suitable The position characteristics can usually be combined with most of the closer frequency modes, and by doing so, it is likely usually avoided to dominate to just a few frequency modes, Applicant of Mentioned above PCT application It is estimated or assumed that there is a trend towards what is suggested in and other patent applications. Such suitability applies when the actual total vibrational energy that is local at the panel member is low rather than high, but is high in terms of the number of frequency modes, i.e. little or no coupling to any mode. It is rather “not activated” in that sense.
[0026]
(Description of Embodiment)
In the distributed mode acoustic panel loudspeaker 10 shown in FIG. 1, as described in WO 97/09842, the transducer 12 of the driving means is placed at a position close to the normal optimum center of the panel member 11 (but off the center). I have. The sandwich structure shown by the core 14 and the skins 15 and 16 is only an example, and many other monolith structures and / or reinforced structures and other structures are possible. In any case, standard inboard In the area Transducer arrangements allow light to pass, for example in the case of transparent or translucent panels for There is a possibility that the area where there is no obstruction can be used.
[0027]
Mainly transparent or translucent resonant mode acoustic panel members will use known transparent piezoelectric transducers such as lanthanum doped titanium zirconate. Rude Let's go. However, since these are relatively expensive, another approach is possible by optimizing the loudspeaker design so that most of the resonant mode acoustic panel member 10 is transparent and unobstructed. The loudspeaker design optimization is selected from the four types of excitation shown in FIG. 2 focused on the edge or perimeter of the panel, and each type is classified as T1-T4 as follows.
The T1-panel member 11 sends a dense wave to the edge (shown along 18A), which is effected by inertial or reference plane related drive transducers.
T2-Panel member 11 sends a lateral flexural wave along the edge (shown along 18A), but is done by flexing the panel edges laterally using a flexure actuating transducer. .
The panel member 11 is twisted as shown across the corner between the T3-edges 18A and 18B, but is effected by either a flexure or inertial drive transducer.
As shown by the T4-edge 18B, linear deflection is directly generated at the edge of the panel member 11, but is performed in the local region of the contact by the inertial action drive transducer.
[0028]
FIG. 3 shows the composite panel 11. Part of Refusal surface FIG. 5 shows the high tension skins 15 and 16 and the structural core 14. Showing Along with the four types of T1-T4 edge / peripheral drive transducers / exciters 31-34 described above used . In practice, fewer than four drive types may be used simultaneously on the panel, provided that they are effectively acoustically and mechanically optimized for the desired band of operation and the particular drive type employed. Good. That is, the optimized panel can be driven by any one or more different drive types.
[0029]
Transparent or translucent edge-driven acoustic panels , It may be a monolithic structure, for example made of glass, or a suitable transparent / translucent core and skin material, with the core surrounded by a skin, see FIG. 3A for this. A visual display unit (VDU) can be described by using the screen as a loudspeaker, and a pair of skins 15A and 16A sandwich a lightweight core 14A of airgel material with transparent adhesives 15B and 16B. If it is, it will preferably have a low mass and high bending rigidity. Airgel materials are extremely light and porous solid materials such as silica. The transparent or translucent skin or skins may be laminated and / or made from a transparent plastic material such as polyester or glass. Conventional transparent VDU screens can be replaced by such transparent acoustic radiation panels, including providing acoustic excitation outside the unobstructed main screen area.
[0030]
A specific example of a suitable silica airgel core material is (RTM) bathogel from BASF. Other possible core materials could include less familiar airgel molding materials including metal oxides such as iron and tin oxide, organic polymers, natural gels, and carbon aerogels. Specific materials for suitable plastic skin laminates include polyethylene terephthalate (RTM) mylar or other transparent materials with appropriate thickness, modulus, and density. Since airgel has a very high shear modulus, extremely thin composites can be made smaller and compatible with other physically important factors to operate under distributed mode acoustic principles.
[0031]
If desired, such a transparent panel can be added to an existing VDU panel and incorporated, for example, as an integrated front panel. In the plasma type display, the inside is kept at a low pressure close to a vacuum, and the acoustic impedance is very low. Inevitably, there is almost negligible acoustic interaction behind the acoustic radiator, which improves performance and eliminates the usual front panel. Even in the case of film-type display technology, a transparent front window can be created using a distributed mode radiator, and the rear display structure can be adjusted in dimensions and specifications to help radiate sound from the front panel. Will be able to deploy. For example, making the back display structure partially acoustically permeable reduces the reflection of waves to the back and improves the performance of the distributed mode speaker element. When the display is a light emitting type, the light emitting element is arranged on the back surface of the transparent distributed mode panel without giving a large impedance to the acoustic characteristics, and the image can be seen from the front side.
[0032]
Transparent distribution resonance Mode loudspeaker, rear projection system of Can also be used for applications, in which case Speaker It can be added to a translucent screen, or the function itself can be incorporated into a suitably prepared surface for rear projection. In this case, the projection surface and screen not only provide both benefits and economics, but also become one component that optimizes acoustic performance. The back skin may be selected to capture the projected image, or the optical properties of the core may be selected for the projection application. For example, in the case of a loudspeaker panel with a relatively thin core, complete optical transparency is not required, it is simply ideal and instead a light transmissive core, such as another grade of airgel or more economical You can also choose a substitute. Special optical properties can also be combined with the core and / or skin surface to produce directional brightness enhancement properties for the transmitted optical image.
[0033]
If the transparent distributed mode speaker has an exposed front surface, for example, providing a conductive pad or conductive area that is visible or transparent so that the user can enter data or commands on the screen can provide additional value. Can be increased. Transparent panels can also be increased in value by applying an optical coating to reduce reflection and / or improve scratch resistance, or simply by providing a scratch resistant coating. Transparent panel cores and skins are used with distributed mode transparent panel speakers or incorporated into displays to shade colors or to improve the visibility ratio in the case of dull hues. A pale color may be applied. During the manufacture of transparent distributed mode panels, invisible wiring, for example in the form of microwires or transparent conductive films, is incorporated with indicators such as light emitting diodes (LEDs) or liquid crystal displays (LCDs), etc. It can be integrated and protected with the panel, and this technique also minimizes degradation of acoustic performance. Designs that do not require overall transparency, such as making only one skin of the panel transparent so that the integrated display underneath it can be seen, are also conceivable.
[0034]
The transducer may be piezoelectric or electrodynamic according to design criteria including price and performance, and is bonded to the panel with a suitable adhesive as shown as a simple contour element in FIG. The T1 type drive excitation shows a state where the inertial transducer 31 excites a longitudinal dense wave to the panel 30. The T2 type drive excitation shows a state in which the bending type transducer 32 is bending directly and locally in order to send a bending wave through the loudspeaker panel 30. The above-described T3 type drive excitation shows a state where the inertial transducer 33 excites the corners of the panel obliquely, thereby exciting the entire loudspeaker panel 30. For the T4 type drive excitation, another inertial transducer 34 is block or semi-circular and deflects one side of the loudspeaker panel 30.
[0035]
Each type of excitation generates a distinctive drive configuration in the panel 30, which is taken into account when designing the overall loudspeaker, including the parameters of the panel 30 itself. The placement of the transducers 31-34 along the panel edges is in fact repeated with the panel design parameters in order to optimize the modal distribution of bending waves or at least to be operationally acceptable. It is conceivable to apply more than one audio channel to the panel 30 of interest, for example via a plurality of drive transducers, according to panel characteristics including, for example, controlled loss and the position and type of drive at or near the edge. . This multi-channel potential is enhanced by signal processing to optimize sound quality and / or to control acoustic radiation characteristics and / or improve perceived inter-channel separation and spatial effects. .
[0036]
A particularly satisfactory drive transducer position along the edge of a substantially rectangular panel member is inboard according to the above-mentioned PCT application of the applicant. region Lines or coordinates parallel to the edges, orthogonal to the optimal or preferred drive transducer position axis This is indicated by a broken line drawn from 42 to 45-48 in FIG. Using drive transducers in at least two of these coordinate-related edge positions 45-48 , Actually practical. FIG. 6 shows in-phase series and series / parallel connections for two and four drive transducers A and B. Other drive devices, including direct one-to-one connections for each transducer means, are possible and often preferred, and reduce unnecessary interaction between transducers and / or electrical signal sources. However, any desired signal conditions, such as differential delay, filtering, etc., may be applied to match the preferred drive transducer positions CP1-CP4 of FIG. 5 for the preferred inboard position PL. Pairing is coordinate axis One of CP1, CP2, CP2 and CP3, CP3 and CP4, CP4 and CP1, and the first preferred pairing is , A conceptual definition of the maximum coverage area That is, the transducer position is such that the area surrounded by the pair of transducers is maximized. In fact, it contains the geometric center X. Such a conceptual area is, of course, not limited to other normally optimal or suitable inboards. In the area Drive transducer Mounting See the indications of complementary positions CL and CP5 and CP6 for the first preferred pairing of drive transducer positions through or including the position.
[0037]
In a panel with very high Q, it is a moderate variation within the high frequency range, but the Cartesian coordinates On the axis Relation Do It is interesting to note that a preferred or optimal pair of drive positions can produce a more spread and uniformly distributed low frequency output than that of the earlier preferred inboard. The off-axis response is similar at high frequencies, but is actually somewhat more symmetric at low frequencies.
[0038]
FIG. 7 shows a pair of transducers that maintain a right angle relative relationship. about The above standard inboard region In Can Suitable transducer position And a line connecting each of a pair of transducer positions arranged in the periphery is perpendicular to each other. , concrete Includes coordinate-related edge drive positions SP1 and SP4. The position of the transducer at the periphery is moved along the periphery so that a right angle relationship is maintained as shown in FIG. test did The result of the experiment is shown. The most feasible / probable pair positions are labeled with pair positions 1a, 1b to 6a, 6d. FIG. 7 actually shows that the transducer pair is a straight line passing through the preferred inboard drive positions SP1,2. Both sides The results of another experiment at the edge are also shown. At positions 2a, 2d and 3a, 3d, few feasible / promising positions were found. It is worth doing more experiments on other pairs or more edge drive positions, and theoretical / systematic studies have been attempted. It should be understood that FIG. 7 is not strictly scaled from the quoted dimensions and as measured at paired positions that give a feasible / probable measured / evaluated result. .
[0039]
FIG. 8 shows a panel 70 having a structure composed of a core 74 and skins 75 and 76, including a transducer 72 attached in the vicinity of a corner, In effect, Standard inboard Transducer mounting position in the area, i.e. Suitable transducer Mounting position Mass body 78 is attached , This mass body mounting position is In fact, one farthest away from the excitation corner by the transducer 72 Position of Or Multi-position A group, this is , As a “virtual” source of flexural wave vibration behavior Like Pretend Has been found to be particularly effective Have The Transducer is on the side from the corner Neighborhood A coordinate position that is substantially centered by 5% of the dimension. To avoid , Ie At least that position Outside To be attached to That is advantageous, This position to avoid A number of resonant modes have nodes Is a place That is, it is confirmed that it is a low vibration activity region.
[0040]
In FIG. 9, ST1 to ST4 indicate one position with respect to one end side or attachment of the transducer adjacent to the end side, that is, a corner portion, a half side length, a quarter side length, and a three-eighth side length, respectively. , And edge clamping of edge positions around the panel / Mass body mounting An overview of the research related to selecting the position of the is shown. For example, an excitation transducer such as 92 for panel 90 of FIG. Side retention / Grip Used with load / clamp by means of a 93A / B magnet.
[0041]
When the corner portion excitation transducer position ST1 is used, the position Pos. 13, 14, 18, 19 Mass body mounting in Assisted by doing (Figure 9A) further Including combinations with other positions Be turned . In the excitation transducer position ST2, a good single mass attachment position is Pos. 6, 7, 8, possibly 9, 11, especially 12, 15, but again, combinations with other positions are possible. Combination 5 When 11 and 6 When 11 is specific of Value, and can include other combinations. At the excitation transducer position ST3, a good single mass loading position is Pos. 5, 6, 7, 13, especially combinations 5 + 13 and 10 + 13, combinations 6 + 18, but there are other combinations. At the excitation transducer position ST4, the best positions are 6, 18, but neither is as good as the positions for the other exciter positions ST1-ST3.
[0042]
Figure 10 shows a standard inboard In the area All suitable drive transducer positions and inboards beyond region A panel-shaped loudspeaker 80 having a non-obstructed region 81 and a transducer 82 located at the periphery are shown. The area 81 may be directly used for display applications, or may represent an entity supported by the panel 80 without affecting the acoustic effect, or an entity through which the loudspeaker panel 80 passes. Closed space and / or transparent or translucent. Both volume and sound quality can be easily enhanced, the volume is controlled by a carefully placed additional drive transducer (not shown), and the sound quality effectively controls a specific mode-like vibration point as a panel termination Enhanced by localized edge clamping which is beneficial to The panel 80 is further shown with a localized elastic suspension 84 that is neutrally or advantageously arranged with respect to the acoustic performance to be achieved. The high pass filter 85 is preferred for the input signal to drive the transducer 82 and conveniently limits to the best reproduction range, eg, 100 Hz or higher for A4 size or equivalent panels. Thus, the problematic low frequency panel / exciter vibrations are eliminated.
[0043]
With respect to acoustic performance, it is useful to control acoustic impedance loading on the panel 80 so that it is relatively low, for example near the periphery or periphery, particularly near the drive transducer 82 where the surface velocity tends to be high. Providing such beneficial control means includes sufficient clearance for the local planar member (eg, about 1-3 centimeters), and / or adjacent peripheral frames, or slots on support means or grill elements or other An opening can be mentioned.
[0044]
Careful trimming of the mechanical attenuation to lead to acoustic improvements including loss of area 81 or its periphery is feasible and useful and should not be cut off at least at high frequencies. This can be accomplished by selecting materials, including monolithic polycarbonate or acrylic, and / or a suitable surface coating, or laminate structure.
[0045]
As a result, acoustic radiation can be effectively concentrated in the peripheral region around the plurality of drive transducers, and one near-field hearing sound for applications with at least a localized virtual sound stage, such as a computer game. It is significantly easier to play more than the acoustic channel. Furthermore, even when a plurality of activated sound sources are combined, at least with respect to an audiovisual presentation or the like, problems do not occur due to the addition.
[0046]
The following table shows the physical parameters associated with the actual panel members used in the study involving FIGS. 11-28.

[0047]
11-14 relates to the second row of high-rigidity panel members, FIG. 15-24 relates to the first row of low-rigidity panel members, and FIG. 25-28 relates to the third row of medium-rigidity panel members. Is.
[0048]
In all the graphs, the vertical axis represents the acoustic output power (dB / W) and the horizontal axis represents the frequency, and the measured acoustic output power is shown as a dotted line actually plotted as a function of frequency. Most of the graphs also show the upper true power line adjustment. As mentioned in the previous sentence, this adjustment is due to the application of a normalization function to a flat line, without the often encountered effects of power drop at low frequencies. The panel resonance Behavior Can be evaluated. It turns out that smoothness of power contributes greatly to sound quality. From this normalized value of actual power output, it is beneficial to generate a smoothness estimate by the reciprocal of the mean square deviation, and most of the bar graphs are of that type.
[0049]
The high stiffness panel member with respect to FIGS. 11-14 is actually somewhat less rigid than that used in FIGS. 7-9 above, but the in-board transducer's previously preferred arrangement That is, it is preferable to place a single transducer at a position corresponding to coordinates 3/7, 4/9 long, or 0.42-0.44 long from the corner. However, for each edge, there is a substantial expansion of the possible positions that can be used between and beyond such positions, and in fact the short and long sides respectively. This is within about 10% and 15% of the middle region, and within 28% and 30% of the quarter length position.
[0050]
Although the other spacing is up to 0.09, at least for the most part, the trial position for the placement at or near the end of the transducer has a preferred coordinate value of 0.42 with respect to the inboard transducer position and the end position. This is based on an interval substantially corresponding to the difference from the side midpoint (0.5). Normal trial positions are therefore 0.08, 0.17, 0.28, 0.33, 0.42, 0.50.
[0051]
Referring to FIG. 23, the graph and bar graph shown are transducers. For installation Shows the best and likely location, local Established About clamped , Less promising transducer attachment It is clear that the location also indicates a location that may improve performance.
[0052]
As far as the placement of a single transducer at or near the edge is concerned, as FIGS. 15 and 25 show, the two other types of test panel members, one with fairly low stiffness and one with intermediate, are also of power Regarding smoothness Is It shows the same advantage as the preferred mounting position on the inboard. However, a panel member with low stiffness exhibits another band from a corner to a position lower than about one-tenth of the side dimension, as measured from the corner, as close to a promising position range. Interestingly, as can be seen from the mean square deviation bar graph of FIG. size Based on For example Through the true output power plot Based on centerline Mean square deviation Like taking Case In , The above band is diagonal Become Quarter length position But Emphasis To become , In most cases Inboard Than the preferred mounting position in This is preferable. Panel members with medium rigidity are close to the direction of the characteristics of panel members with high rigidity, and are suitable for inboard. Mounting Between coordinate positions To spread Promising Mounting position must be present Is also expected around 1 / 10th position of is there Installation position exists thing Also shows .
[0053]
If you examine the true output power plot, Mode characteristics In terms of the expected quality of sound reproduction, i.e. the effect on the number and uniformity of excitations in the resonant mode, between the best indicated edge position of the transducer and the achievable edge position. It will be apparent to those skilled in the art that there are differences. For positions indicated as preferred based on a smoothness assessment of output power, Mode characteristics Of course, it is possible to process the input signal towards what is shown after the above normalization, especially in the form of signal conditioning or equalization. The low frequency can be selectively amplified. This achieves the power available using the optimized location on an efficiency basis (actually beyond that), but it is not efficient because more input power must be used. it is obvious.
[0054]
Therefore, First As indicated, other ways to increase the power of low frequencies have been studied, Baffle placement And / or selectively spaced local clamping or full edge clamping. FIGS. 18A, B, and C show a perimeter baffle in 60% more area than a low stiffness panel, a fixed clamp on all three edges not used for transducer positions, and such a baffle. It is shown that the low-frequency output is increased substantially effectively for both of those subjected to clamping and clamping. Such a baffle Mode characteristics However, it is not always feasible for a specific application. Therefore, a well-studied clamping seems to be valuable in terms of alternative transducer edge positions for low stiffness panel members. As can be seen from each of the bar graphs in FIGS. 31B, 31C, and 31D, the evaluation based on the efficiency does not clamp the edge of the transducer position along the length, but at two parallel edges or three edges. Both the case of clamping all edges and the case of local clamping of 7 corners and corners as shown in Fig. 29 "X" tend to emphasize the quarter long point. Indicated. However, “X” in FIG. as well as In the case of 13-point clamping of “O”, the emphasis point clearly moved to the preferred coordinate position of the inboard. The evaluation of the clamped panel member based on power smoothness gives nearly the same results for the best transducer position, as shown in the bar graphs of FIGS. 19A, 20B, 21B and 22, but for the next preferred position Are quite different and are generally confirmed by examining actual output power plots.
[0055]
Actually, based on examination by skilled workers Favorable results And smoothness of power output Based on It has been found that there is generally a strong correlation with evaluation. This is not much different anyway But, If there is no practical factor to prioritize efficiency rather than sound quality, such an assessment may be slightly preferable There is a direction to confirm that.
[0056]
Another for localized edge clamping Apply Is related to improving the undesired transducer edge position, About this, 23A, B bar graph of Figure In The right side, not the intended left side Please refer to the part shown in . The target case is for low-rigidity panel members. Horn Edge Is the whole Clamping Shi , Transducer means The edge where the is placed The clamp is localized along the same edge, and the clamping position is changed over 7 points. In both cases, improvement was seen at about a quarter length from the corner farther away from the exciter, but see the bar graph on the right side of FIG. 23B for no clamping condition. As shown in FIG. 23A, in the case of all edge clamping range Is larger.
[0057]
If there is a discrepancy between the power efficiency rating and the power smoothness rating, the transducer Attached Corner against edge Part Panel members that have been clamped to , corner Force the movement of the part to zero It is important to keep this in mind. In other words, vibration activity Anti-node Before reaching the peak, half the wavelength for the relevant resonant mode of There should be no more than a distance. corner Part Transducer position close to But Superiority Be Should be treated with caution as it can result in low power / efficiency, although smoothness can result in very small ridges in the waveform, coupled with all relevant resonant mode waveforms. It is. It is therefore recommended to examine the corresponding power / efficiency assessment. The best in practice is often the case when there is a substantial agreement between the two bases of the evaluation, otherwise there is a particular compromise that applies to a particular application, However, it is preferable to take into consideration the examination by a skilled person in the power / frequency graph.
[0058]
For some investigated panel members with high or moderate stiffness, a fairly consistent measure of measurement results was observed for the best transducer edge position, but significantly for other probable positions. Differences were noted. It has also been found that lower stiffness panel members are less critical with respect to the probable transducer edge positions.
[0059]
This position becomes even more apparent when considering the use of two or more transducer means on the edge of the same panel member. The position where the connection with the resonance mode of the panel member is strengthened Resonance mode And panel members But The complexity of the inevitable combination interaction with the resonance vibration pattern that is originally possessed is combined with such a distributed vibration pattern generated only at the edge of the panel. Established inboard In the area Suitable for transducer Mounting Position coordinates axis There are notable changes compared to simple rules based on. However, the evaluation procedure can use an effective tool to find a good combination of edge-located transducer positions.
[0060]
In FIGS. 13A and 14A, the high-rigidity panels in the above table are One The transducer means are arranged along the long side at a position within a tolerance range of about 0.38-0.45 with respect to a preferred position of 0.42. Second of The transducer means along the nearest short side Position 14A, in FIG. 14A, the preferred position is 0.42. Is the farthest position 0.58 The center As , Other locations about a quarter, one third, two thirds from the common corner When Compared to the edge advantage. Interestingly, when the second transducer means is fixed at a preferred position of about 0.58 along the short panel edge and the other transducers are repositioned along the long panel edge (see FIGS. 13B and 14B), the optimum position And the next best position is about one-fifth (0.17) and one-quarter long positions along the long panel edges, both positions from the starting position (about 0.42) for power smoothness. Is also good. This is obviously a procedure that can be further applied in an iterative method, however, it is recommended to develop either or both of power / efficiency assessment and expert review, especially where the position converges within the procedure. No or recommended as a good location is recommended in cases where it is actually less preferred than desired (or previously unfavorable in the procedure).
[0061]
FIGS. 16A and B are low stiffness panel members that apply a preferred approximately 0.42 transducer position to the long side, of The transducer shows the results of the study when changing position along the nearest short side. There is not much difference in increasing power smoothness, the best three locations are the closest 0.42 dominant positions with the two closest corners, and there are generally other suitable positions for some combinations In the quadrant.
[0062]
During ~ Degree rigidity Have A similar study on panel members is shown in adjacent quadrants as shown in FIGS. In Preferred 0.42 transducer position (actually 0.58) Is preferable Strongly indicated.
By far Low rigidity of Returning to the case of panel members, two effects Enough Defined The Optimal Exciter position / It can be seen that this contributes to a near-optimal exciter position. One is that the panel mode for the optimized frequency range is higher than for a rigid panel member. Therefore, the panel member becomes an approximate body closer to the continuum, and the smoothness of the output power. But Transducer position In Dependence Degree to do , Especially the second transducer position In Dependence Degree to do Is weakened.
Another effect is , Very low mechanical impedance of panel members The , for that reason, Less dependent on transducer position for energy transfer Become Especially Related . The related mechanism will be described below.
[0063]
Referring to 100 and 101 in FIG. 30, the point load to which the mechanical impedance (Zm) of the panel member is applied. Under The resulting movement Ki Decide. panel of Much more than impedance small Or And An object with almost equal mechanical impedance is attached to the panel member. If you have In the position where the object is attached, a strong bias occurs in the panel motion. When a moving coil type excitation transducer is attached to the panel, it is the same as connecting the panel to a grounded mass (see transducer magnet cup, 102) via a spring (voice coil suspension, see 102). If the impedance of such a spring is too close to the panel impedance, it will define some panel motion at the transducer position. At this spring limit, which generally defines the point motion of the transducer position, there will be no dependence of the input power on the exciter position. In practice, the ratio of spring impedance to panel impedance has a profound effect on the optimal transducer position, so the result is no longer so obvious for the best / closest transducer position.
[0064]
machine Target Impedance is , panel end Neighborhood Part Then Than the part Equivalent In Low Because This low No machine Target Impedance is , Inboard In the area Transducer When can be installed than end Side In Transducer If you can install It has a great influence, which means that the transducer and the voice coil suspension have a greater influence. In particular, in the low rigidity panel member of the above table,
The mechanical impedance of the panel body is
Zmbody = 2.7Nsm ^-1 It is.
The mechanical impedance at the edge of the panel is about half of Zmbody, ie
Zmerge = 1.3Nsm ^-1 It is.
The compliance of the voice coil suspension of the transducer used is
Cms = 0.52 × 10 ^-3 mN ^-1 It is.
[0065]
resonance Each mode frequency In machine Target The impedance should be lower than the average impedance Zmerge. Therefore, it is possible to estimate the frequency at which the exciter has a strong influence on the panel member below, for example, where the impedance of the voice coil suspension is about one-fifth of the average impedance at the panel edge. is there. Therefore,

Giving an estimate of 1200 Hz, below which the transducer and panel are intentionally coupled, but within the frequency range of optimization.
[0066]
Considering a transducer and a panel member with such a low mechanical impedance as one coupled system, the transducer partially defines the impedance of the panel member, and the dependence of the output power smoothness on the transducer position is Lower.
Repeating such an analysis for a stiff panel yields a corresponding frequency of 130 Hz, which is outside the optimized frequency range.
[Brief description of the drawings]
FIG. 1 shows a distributed mode acoustic panel fitted with a transducer as generally described in another PCT application by the applicant.
FIG. 2 is a schematic diagram showing four different ways of exciting the periphery or edge of an acoustic panel.
FIG. 3 is a diagram showing how a transducer can be placed at the edge of an acoustic panel to perform the action shown in FIG. 2;
FIG. 3A shows the panel of FIG. 3 being a transparent panel.
FIG. 4 is a schematic diagram illustrating four preferred peripheral positions for a transducer, corresponding to the in-board transducer of FIG.
FIG. 5 shows four preferred positions corresponding to another preferred inboard drive position and a preferred pair of positions corresponding to complementary or virtual inboard drive positions.
FIG. 6 shows how any pair and all four drive transducers in such a preferred position were connected for testing.
FIG. 7 illustrates what is possible when there are few suitable paired edge drive transducer positions.
FIG. 8 is in a corner driving position and an inboard suitable driving position. Useful mass mounting FIG.
FIG. 9 shows four normally unfavorable edge drive transducer positions for many edges Mass body mounting Or it is a figure shown with a clamping position.
FIG. 9A: Test Mass body And how a drive transducer is associated with a panel.
FIG. 10 shows an unobstructed inboard area in the peripheral position for the drive transducer, clamp end, elastic suspension / attachment.
FIG. 11A is a graph showing the output power / frequency relationship for a substantially rectangular panel member with very high stiffness with a single transducer placed along a long side.
FIG. 11B is a graph showing the output power / frequency relationship for a very rectangular, substantially rigid panel member with a single transducer positioned along a short side.
FIG. 12A is a related bar graph showing measured values of smoothness of output power.
FIG. 12B is a related bar graph showing measured values of smoothness of output power.
FIG. 13A is a graph showing the relationship of output power / frequency when two transducers are arranged and one position is moved on the short side or the long side.
FIG. 13B is a graph showing the relationship of output power / frequency when two transducers are arranged and one position is moved on the short side or the long side.
FIG. 14A is a related bar graph showing measured smoothness of output power.
FIG. 14B is a related bar graph showing measured smoothness of output power.
FIG. 15A is a graph showing the output power / frequency relationship for a panel member with fairly low stiffness with a single transducer positioned along the long side.
FIG. 15B is a power smoothness bar graph for a panel member with fairly low stiffness with a single transducer placed along the long side.
FIG. 16A is a graph showing an output power / frequency relationship when the second transducer is disposed along the short side.
FIG. 16B is a power smoothness bar graph when the second transducer is arranged along the short side.
FIG. 17 is a graph comparing the power output when the transducer is preferably on the inboard and on the side with a panel member having low rigidity.
FIG. 18A is a graph showing the effect of buffing.
FIG. 18B is a graph showing the effect of three-end side clamping;
FIG. 18C is a graph showing both the buffing effect and the three-end side clamping effect.
FIG. 19A is a panel member with low rigidity, 3 Horn FIG. 6 is a graph showing the output / frequency relationship when clamped along an edge and the transducer is on the fourth edge.
FIG. 19B shows a panel member with low rigidity, 3 Horn FIG. 6 is a power smoothness bar graph when clamped along an edge and the transducer is on the fourth edge.
FIG. 20A is a panel member with low rigidity, parallel 2 Horn FIG. 6 is a graph showing the output / frequency relationship when clamped on an edge and the transducer is on another edge.
FIG. 20B is a panel member with low rigidity, parallel 2 Horn Figure 6 is an associated power smoothness bar graph when clamped on an edge and the transducer is on another edge.
FIG. 21A is a graph showing the output / frequency relationship when a panel member with low rigidity is clamped locally in the corner / edge middle and the transducer is on another long side.
FIG. 21B is a graph showing the output / frequency relationship when a panel member with low rigidity is clamped locally in the corner / edge middle and the transducer is on another long side.
FIG. 22 is a power smoothness bar graph for a low stiffness panel member where local clamping is further applied during another corner / midpoint clamping.
FIG. 23A: Normalization with a panel member with low stiffness, with 3 edge sides clamped at 7 points, and another local clamp location along another side where the transducer means is in an unfavorable position It is a bar graph which shows power evaluation without.
FIG. 23B is a non-rigid panel member without full edge clamps, and the other local clamp location is along the other side where the transducer means is in an unfavorable position, without normalization. It is a bar graph which shows power evaluation.
FIG. 24A is a graph showing the relationship between power output and frequency for a case where three edge sides are clamped and evaluated by normalization.
FIG. 24B is a related power smoothness bar graph for a case where the three edges were clamped and evaluated by normalization.
FIG. 25A is a graph showing a power output / frequency relationship when a panel member having medium rigidity and a single transducer are arranged along the long side and normalization is performed.
FIG. 25B is a related power smoothness bar graph for a moderately rigid panel member with a single transducer placed along the long side and normalized.
FIG. 26A is a graph showing the output / frequency relationship for a panel member with medium stiffness, clamped locally at 7 points, and evaluated without normalization.
FIG. 26B is a power evaluation bar graph for a panel member with medium stiffness, clamped locally at 7 points, and evaluated without normalization.
FIG. 27A is a graph similar to FIG. 26A but showing a case where normalization is performed for power smoothness evaluation.
FIG. 27B is a graph similar to FIG. 26B but showing a case where normalization is performed for power smoothness evaluation.
FIG. 28A is a power output graph in the case where the panel member has a medium rigidity and the second transducer is disposed along the short side.
FIG. 28B is a power smoothness bar graph in the case of a panel member having a medium rigidity and the second transducer arranged along the short side.
FIG. 29 is a diagram showing 7-point and 13-point local clamping applied above.
FIG. 30 is a schematic diagram useful for explaining the influence of compliance within a transducer.
FIG. 31A is a bar graph showing power efficiency with respect to various edge conditions for a panel member having low rigidity.
FIG. 31B is a bar graph showing power efficiency with respect to various edge conditions for a panel member having low rigidity.
FIG. 31C is a bar graph showing power efficiency for various edge conditions for a panel member with low stiffness.
FIG. 31D is a bar graph showing power efficiency with respect to various edge conditions for a panel member having low rigidity.
FIG. 31E is a bar graph showing power efficiency with respect to various edge conditions for a panel member having low rigidity.

Claims (23)

A panel member having a plurality of sides and a transducer connected to the panel member, and a plurality of resonance modes of bending wave vibration induced in the panel member by the transducer are distributed in the panel member to generate an acoustic output. A distributed resonance mode type active acoustic device that has been generated ,
The panel member can maintain a plurality of bending waves in the operating frequency range over an active area extending in a plane direction of the panel member, so that the distribution of the plurality of resonance modes of the bending wave vibration affects the acoustic performance together with the transducer. And
The panel member has at least one inboard region in the active area in which a plurality of low-frequency resonant bending wave modes within the operating frequency range are vibrationally active antinodes;
The transducer is coupled to said the panel member at a peripheral position of the panel member corresponding to two orthogonal coordinate axes which intersect at a point at least one inboard region, substantially shielding the at least one inboard region In such a way that an operational interaction between the panel member and the transducer is achieved.
A distributed resonance mode type active acoustic device. A panel member having a plurality of sides and a transducer connected to the panel member, wherein a plurality of resonance modes of bending wave vibration induced in the panel member by the transducer are distributed in the panel member to generate an acoustic output. A distributed resonance mode type active acoustic device that has been generated,
The panel member can maintain a plurality of bending waves in an operating frequency range over an active area extending in a plane direction of the panel member, and a distribution of a plurality of resonance modes of the bending wave vibration influences acoustic performance together with the transducer. And
The panel member has at least one inboard region in the active area in which a plurality of low frequency resonant bending wave modes within the operating frequency range are vibrationally active antinodes;
The transducer is coupled to the panel member at a peripheral position of the panel member that lies on a line that passes through a point of the at least one inboard region and is parallel to or perpendicular to the principal axis of the active area, and the at least one inboard region is An operational interaction between the panel member and the transducer is achieved in a substantially unobstructed state, wherein the main axis of the active area passes through the center of the active area. Defined as the axis parallel to the longest side of the active area
A distributed resonance mode type active acoustic device. 3. The distributed resonance mode type active acoustic device according to claim 1, wherein the panel member is clamped along a part of an edge thereof. Clamping of said end edges, distributed resonant mode type active acoustic device according to claim 3, wherein it has been found locally provided. 5. The distributed resonance mode type active acoustic device according to claim 3 or 4 , wherein the localized edge clamps are plural. The spacing between the plurality of localized edge clamps is related to the wavelength of the low frequency resonant mode, thereby increasing their contribution to the acoustical action of the device. 5. The distributed resonance mode type active acoustic device according to 5. Wherein the plurality of localized clamp end side is distributed resonant mode type active acoustic device according to claim 5 or claim 6, characterized in that it is in connection with the more than one side. The panel member is substantially rectangular, said plurality of localized clamp end side is claim from claim 5, I characterized in that it is in relation to the side that is not combined with the transducer The distributed resonance mode type active acoustic device according to any one of 7 to 7 . Wherein the plurality of localized clamp end side is distributed resonant mode type active acoustic device according to claim 8, characterized in that the midpoint of each corner and the sides. 4. The distributed resonance mode type active acoustic device according to claim 3 , wherein the clamp on the end side extends along the panel member. Distributed resonant mode type active acoustic device according to claim 10 clamp said end edges, characterized in that extending along at least one side not combined with the transducer. The distributed resonance mode type active acoustic device according to claim 11 , wherein the panel member is substantially rectangular, and the clamp on the end side extends along two parallel sides. 12. The distributed resonance mode type active acoustic device according to claim 11 , wherein the end side clamp extends along three sides. The panel member is substantially rectangular with four corners and four sides , and the peripheral position is at each intermediate region along one of the short side and the long side of the panel member . distributed resonant mode type active acoustic device according to any one of claims 1 to 13, characterized in that there from one within a distance by 10% to 15% of the total length of該辺. The panel member is generally rectangular having four corners and four sides , and the peripheral position is 28% to 30% of the total length of the side from one of the corners along one side of the panel member. The distributed resonance mode type active acoustic device according to any one of claims 1 to 14, wherein the active acoustic device is in a remote range . The panel member is generally rectangular with four corners and four sides , and the peripheral position extends from one of the corners to 38 % to 45 % of the length of the side along one side of the panel member. distributed resonant mode type active acoustic device according to any one of claims 1 to 14, characterized in that in the range away. The distributed resonance according to claim 16 , wherein the peripheral position is within a range of 42 % to 44 % of the total length of the side from one of the corners along one side of the panel member. Mode type active acoustic equipment. The distributed resonance mode type active acoustic device according to any one of claims 1 to 17 , wherein the panel member has at least two of the transducers on an end side having the transducers. The panel member has a shape having a plurality of sides, distributed resonant mode type active acoustic device according to claim 18, wherein the transducer is combined with at least two sides. The panel member is substantially rectangular, distributed resonant mode type active acoustic device according to claim 18 or claim 19, wherein the transducer is combined with the long and short sides. 21. The distributed resonance mode type active acoustic device according to any one of claims 1 to 20 , further comprising a baffle extending around and beyond the panel member. The distributed resonance mode type active acoustic device according to any one of claims 1 to 21, wherein the panel member is at least partially transparent or translucent. The distributed resonance mode type active acoustic device according to any one of claims 1 to 22 , wherein the transducer is an electromechanical type.

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