【考案の詳細な説明】[Detailed explanation of the idea]
本考案は平面スピーカに係り、特に低い周波数
の分割振動や寄生振動の発生を防止しうる平面ス
ピーカを提供することを目的とする。
第１図ａ，ｂ、及びｃは従来の平面スピーカの
構造をそれぞれ示す図で、そのうち第１図ａは平
面図、第１図ｂは第１図ａの−線における断
面矢視図、第１図ｃは第１図ａの−線におけ
る断面矢視図である。同図において、１は振動
板、２はボイスコイル、３は磁気回路、４はエツ
ジ、５はボイスコイルボビンである。
振動板１はエツジ４により周辺を振動可能な状
態に支持されている。ボイスコイル２は振動板１
と一体となつた細長い長円筒状のボイスコイルボ
ビン５に巻き付けられ、同時に、磁性金属板には
さまれたマグネツトにより構成された磁気回路３
に遊嵌されており、磁気回路３の電磁作用によ
り、振動板１が振動して音を発生する。ボイスコ
イル２及び磁気回路３は一組となつており、振動
板１の背面全体に並列に並んで設けられている。
このような構成の従来の平面スピーカは、その
構造からボイスコイルの長手方向の振動板とボイ
スコイルそのものの剛性は大きいが、矢印Ｐ−
P′に示す長手方向と直交する方向の剛性は小さ
い。そのため、発生する音の低い周波数で分割振
動や寄生振動等を発生しやすく、実用上これらが
大きな問題点であつた。
本考案は上記の問題点を解消したものであり、
以下図面と共にその一実施例について説明する。
第２図ａ，ｂ、及びｃは本考案になる平面スピ
ーカの一実施例の構造を示す図で、そのうち第２
図ａは平面図、第２図ｂは第２図ａの−線に
おける断面矢視図、第２図ｃは第２図ａの−
線における断面矢視図である。同図において、前
出の第１図ａ，ｂ、及びｃと同一部分には同一符
号を付してその説明は省略する。
６は本考案平面スピーカの要部をなす補強の為
のリブである。同図に示すように、左右一組の磁
気回路３にはボイスコイル２の長手方向の中間部
分にあたる位置に数mm程度の間隙ｇを設け、さら
にその部分の振動板１に補強材となるリブ６を設
け、さらにリブ６はボイスコイル２を保持するボ
イスコイルボビン５にも接合されて、その補強部
材となつている。
この補強部材の位置は振動板１及びボイスコイ
ル３の例えば、剛性が小さい中央部分に設けるこ
とによつて補強の効果は大きいものとなる。
また、磁気回路３の間隙ｇによる磁束の減少
は、間隙ｇが数mm以内であれば、数％と極めて少
なくて済み、何ら問題はない。そして、本考案の
実施例による補強によつて低い周波数での分割振
動や寄生振動の発生を防止することができる。
次に本考案による平面スピーカの効果を確かめ
るために、第３図、第４図に従来及び本考案の平
面スピーカの周波数特性を対比して測定した結果
を示す。また、例えば、一組の磁気回路３の長手
方向が約80mmのものに３mmの間隙ｇを設けた場合
のデータの一部を下記の表にまとめて示す。
The present invention relates to a planar speaker, and an object of the present invention is to provide a planar speaker that can prevent split vibrations and parasitic vibrations at particularly low frequencies. Figures 1a, b, and c are diagrams showing the structure of a conventional flat speaker, respectively, of which Figure 1a is a plan view, Figure 1b is a sectional view taken along the - line in Figure 1a, and Figure 1b is a cross-sectional view taken along the - line in Figure 1a. FIG. 1c is a sectional view taken along the - line in FIG. 1a. In the figure, 1 is a diaphragm, 2 is a voice coil, 3 is a magnetic circuit, 4 is an edge, and 5 is a voice coil bobbin. The diaphragm 1 is supported by an edge 4 so that its periphery can vibrate. Voice coil 2 is diaphragm 1
A magnetic circuit 3 is wound around an elongated cylindrical voice coil bobbin 5 that is integrated with a magnetic circuit 3, and is also constituted by a magnet sandwiched between magnetic metal plates.
The diaphragm 1 vibrates and generates sound due to the electromagnetic action of the magnetic circuit 3. The voice coil 2 and the magnetic circuit 3 form a set and are arranged in parallel over the entire back surface of the diaphragm 1. In conventional planar speakers with such a configuration, the diaphragm in the longitudinal direction of the voice coil and the voice coil itself have high rigidity due to its structure.
The stiffness in the direction perpendicular to the longitudinal direction, indicated by P′, is small. As a result, split vibrations, parasitic vibrations, etc. are likely to occur at low frequencies of the generated sound, and these have been a major problem in practical use. This invention solves the above problems,
An embodiment will be described below with reference to the drawings. Figures 2a, b, and c are diagrams showing the structure of an embodiment of the flat speaker according to the present invention.
Figure a is a plan view, Figure 2 b is a sectional view taken along the - line in Figure 2 a, and Figure 2 c is a - line in Figure 2 a.
FIG. In this figure, the same parts as those in FIGS. 1a, b, and c described above are given the same reference numerals, and the explanation thereof will be omitted. Reference numeral 6 denotes a reinforcing rib that forms the main part of the flat speaker of the present invention. As shown in the figure, a gap g of approximately several mm is provided between the left and right magnetic circuits 3 at a position corresponding to the longitudinally intermediate portion of the voice coil 2, and a rib serving as a reinforcing material is provided on the diaphragm 1 at that portion. Further, the rib 6 is also joined to the voice coil bobbin 5 that holds the voice coil 2, and serves as a reinforcing member thereof. By locating this reinforcing member at, for example, the central portion of the diaphragm 1 and voice coil 3 where the rigidity is low, the reinforcing effect will be great. Furthermore, if the gap g in the magnetic circuit 3 causes a decrease in magnetic flux, the decrease in magnetic flux can be as small as a few percent if the gap g is within several mm, and there is no problem. Further, the reinforcement according to the embodiment of the present invention can prevent split vibrations and parasitic vibrations from occurring at low frequencies. Next, in order to confirm the effect of the planar speaker according to the present invention, FIGS. 3 and 4 show the results of comparing and measuring the frequency characteristics of the conventional planar speaker and the planar speaker according to the present invention. Further, for example, part of the data when a gap g of 3 mm is provided in a set of magnetic circuits 3 having a length of about 80 mm is summarized in the table below.
【表】
同表に示すように、600Hzにおける歪が66dBか
ら42dBに大幅に減少する（24dBの改善）と共
に、低い周波数の音圧レベルは増加する。また、
構造の改良による磁束密度の減少は約２％にすぎ
ず、何ら問題はない。
以上のように、本考案になる平面スピーカは、
振動板に設けた長円筒状のボイスコイルを磁気回
路中に遊嵌し、ボイスコイルの長手方向の略中間
部分に対応する位置の磁気回路に間隙を設け、間
隙に対応する位置の振動板に、間隙に遊嵌しうる
補強部材を設けた構成であるので、従来の平面ス
ピーカに比して、ボイスコイルの長手方向と直交
する方向の振動板を補強部材（リブ）によつて補
強して、その剛性を大きくでき、低い周波数での
分割振動や寄生振動の発生を防止できると共に、
歪み、耐入力等の向上がはかれ、さらに、スピー
カとしての音圧の増加もはかれる等の数々の効果
を有するものである。[Table] As shown in the table, the distortion at 600Hz is significantly reduced from 66dB to 42dB (an improvement of 24dB), while the sound pressure level of low frequencies increases. Also,
The reduction in magnetic flux density due to structural improvement is only about 2%, and there is no problem. As mentioned above, the planar speaker of the present invention is
An elongated cylindrical voice coil provided on a diaphragm is loosely fitted into a magnetic circuit, a gap is provided in the magnetic circuit at a position corresponding to approximately the middle portion in the longitudinal direction of the voice coil, and a gap is provided in the diaphragm at a position corresponding to the gap. Since the structure includes a reinforcing member that can fit loosely into the gap, compared to conventional flat speakers, the diaphragm in the direction perpendicular to the longitudinal direction of the voice coil is reinforced with the reinforcing member (rib). , its rigidity can be increased and split vibrations and parasitic vibrations can be prevented from occurring at low frequencies.
It has many effects such as improved distortion and input resistance, and also increases sound pressure as a speaker.
【図面の簡単な説明】[Brief explanation of the drawing]
第１図ａ，ｂ、及びｃは従来の平面スピーカの
構造を示す図、第２図ａ，ｂ，ｃは本考案になる
平面スピーカの一実施例の構造を示す図、第３図
は従来の平面スピーカの周波数特性を示す図、第
４図は本考案になる平面スピーカの周波数特性を
示す図である。
１……振動板、２……長円筒状のボイスコイ
ル、３……磁気回路、４……エツジ、５……ボイ
スコイルボビン、６……リブ、７……間隙。
Figures 1 a, b, and c are diagrams showing the structure of a conventional flat speaker; Figure 2 a, b, and c are diagrams showing the structure of an embodiment of the flat speaker according to the present invention; Figure 3 is a diagram showing the structure of a conventional flat speaker. FIG. 4 is a diagram showing the frequency characteristics of the flat speaker according to the present invention. 1... Vibration plate, 2... Long cylindrical voice coil, 3... Magnetic circuit, 4... Edge, 5... Voice coil bobbin, 6... Rib, 7... Gap.