JP2568241Y2 - Magnetic circuit for speaker - Google Patents
Magnetic circuit for speakerInfo
- Publication number
- JP2568241Y2 JP2568241Y2 JP9145591U JP9145591U JP2568241Y2 JP 2568241 Y2 JP2568241 Y2 JP 2568241Y2 JP 9145591 U JP9145591 U JP 9145591U JP 9145591 U JP9145591 U JP 9145591U JP 2568241 Y2 JP2568241 Y2 JP 2568241Y2
- Authority
- JP
- Japan
- Prior art keywords
- magnetic
- magnet
- magnetic circuit
- speaker
- upper plate
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Landscapes
- Audible-Bandwidth Dynamoelectric Transducers Other Than Pickups (AREA)
Description
【考案の詳細な説明】[Detailed description of the invention]
【０００１】[0001]
【産業上の利用分野】本考案は、内磁型に使用した主磁
石の性能を高度に引き出すとともに、 副磁石により周囲
への漏洩磁束を軽減したスピーカ用の磁気回路に関する
ものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic circuit for a loudspeaker in which the performance of a main magnet used for an inner magnet type is brought out to a high degree and a leakage magnetic flux to the surroundings is reduced by a sub magnet.
【０００２】[0002]
【従来の技術】従来この種のスピーカ(11')の磁気回路
(5")は、図７，図８に示した様に、下部プレート(2e')
の内底面に設けた凹部に、 円柱状の例えばアルニコ磁石
(3')を載置し、その上にセンタポール(1')を固着して、
上部プレート(2c')の中心磁気空隙穴(2d')内に、前記の
センタポール(1')の先端磁極部(1a')を覗出させて、円
筒ヨーク(2')側面部(2a')の下部側面部(2b')を、 前記の
下部プレート(2e')の側面縁立て部(2f')の内面部に嵌合
して結合固定し、円環状磁気空隙(6')を形成したいわゆ
る内磁型磁気回路構造が主であった。2. Description of the Related Art Conventionally, a magnetic circuit of a speaker (11 ') of this kind.
(5 ") is the lower plate (2e ') as shown in FIGS.
In the concave part provided in the inner bottom surface of the column, for example, a cylindrical Alnico magnet
Place (3 '), fix the center pole (1') on it,
In the center magnetic gap hole (2d ') of the upper plate (2c'), the tip magnetic pole portion (1a ') of the center pole (1') is viewed, and the side surface (2a) of the cylindrical yoke (2 ') is seen. '), The lower side surface portion (2b') of the lower plate (2e ') is fitted and fixed to the inner surface portion of the side edge portion (2f') of the lower plate (2e '), thereby forming an annular magnetic air gap (6'). The so-called inner magnet type magnetic circuit structure formed was mainly used.
【０００３】そして、 前記磁気回路(5")の磁気空隙(6')
内にボイスコイル(8')をダンパ(9')で支持し、 その先端
の外周をフレーム(7')に貼り付けた振動板(10')の先端
部を取り付けて、 スピーカ(11')として組み立てられて
いた。The magnetic gap (6 ') of the magnetic circuit (5 ")
The voice coil (8 ') is supported by a damper (9') inside, and the tip of the diaphragm (10 ') attached to the frame (7') is attached to the outer periphery of the tip, and the speaker (11 ') Was assembled as
【０００４】[0004]
【考案が解決しようとする課題】したがって、従来のこ
の種の内磁型磁気回路(5")にあっては、図８に示すよう
に、磁気空隙(6')の部分が磁気回路(5")中の磁路全行程
の内、 最も磁気抵抗が大きく、 そのために磁力線の流れ
が、 磁気空隙(6')から外部へ飛び出して漏洩する成分が
殆どで、 ボイスコイルの駆動力の根源となる磁気空隙
(6')内を通過する磁束の比率が小さい（図８）ので、 能
率の良いスピーカが得られないという問題があった。Therefore, in this type of conventional internal magnetic type magnetic circuit (5 "), as shown in FIG. 8, the magnetic gap (6 ') is formed by the magnetic circuit (5'). The magnetic resistance is the largest in the entire path of the magnetic path in "). Therefore, the flow of the lines of magnetic force mostly leaks out of the magnetic air gap (6 ') and leaks out. Magnetic air gap
Since the ratio of the magnetic flux passing through (6 ') is small (FIG. 8), there is a problem that an efficient speaker cannot be obtained.
【０００５】そこで、本考案は、このような従来の内磁
型磁気回路(5")が有していた問題点を解決するために、
主磁石(3)には従来の例えばアルニコ磁石を使用し、同
様のアルニコ磁石を副磁石(4)として磁路の一部に使用
することによって、主磁石による磁気回路(5)の性能発
揮と、 副磁石(4)の起磁力を利用して、 磁気空隙(6)の外
部に漏れる漏洩磁気を少なくして、 主、 副両磁石(3),
(4)の使用効率を高めて、磁石のスペースファクタの向
上を図ることを目的とし、磁気空隙(6)の磁束密度を飛
躍的に向上させて、 小形で、 強力、 かつ高能率なスピー
カに適した磁気回路(5)を提供しようとするものであ
る。Accordingly, the present invention has been made to solve the problem of the conventional inner magnet type magnetic circuit (5 ").
By using a conventional alnico magnet as the main magnet (3) and using a similar alnico magnet as a sub magnet (4) in a part of the magnetic path, the performance of the magnetic circuit (5) by the main magnet can be exhibited. Utilizing the magnetomotive force of the secondary magnet (4) to reduce the leakage magnetism leaking outside the magnetic air gap (6), the primary and secondary magnets (3),
With the aim of improving the use efficiency of (4) and improving the space factor of the magnet, the magnetic flux density of the magnetic air gap (6) is dramatically improved, making it a compact, powerful and highly efficient speaker. It is intended to provide a suitable magnetic circuit (5).
【０００６】[0006]
【課題を解決するための手段】該目的を達成するための
本考案の構成を、実施例に対応する図１乃至図２を用い
て説明すると、本考案は、内磁型磁気回路において、 上
部プレート(2c)の上端部(2d)に穿設した中心穴(2e)の内
側面(2h)に、 上部プレート(2c)と略厚さを等しくした直
円環状の磁石(4)を嵌入して保持し、 前記副磁石(4)の中
心穴の内側面を、磁気空隙(6)の外側面(6e)として形成
し、 主磁石(3)の磁路方向に直列に磁石(4)を挿入装着し
て、 該磁石(4)を半径方向に着磁したスピーカ用磁気回
路(5)である。The structure of the present invention for achieving the above object will be described with reference to FIGS. 1 and 2 corresponding to the embodiment. A right annular magnet (4), approximately the same thickness as the upper plate (2c), is fitted into the inner surface (2h) of the center hole (2e) drilled in the upper end (2d) of the plate (2c). The inner surface of the center hole of the auxiliary magnet (4) is formed as the outer surface (6e) of the magnetic gap (6), and the magnet (4) is connected in series in the magnetic path direction of the main magnet (3). A speaker magnetic circuit (5) inserted and mounted and magnetized in the radial direction with the magnet (4).
【０００７】[0007]
【作用】本考案は、このような構造としたものであるか
ら、図７に示す従来の例えばアルニコ磁石を使用した主
磁気回路の磁路の一部に直列に、 副磁石(4)を挿入する
ことによって、図１，図２に示すように、副磁石(4)の
起磁力を利用して、 磁気空隙(6)の外部に漏れる漏洩磁
気を少なくして、 磁気空隙(6)内に磁束を集中すること
ができる。According to the present invention, the auxiliary magnet (4) is inserted in series with a part of the magnetic path of the conventional main magnetic circuit using an alnico magnet as shown in FIG. As shown in FIGS. 1 and 2, by using the magnetomotive force of the sub-magnet (4) to reduce the leakage magnetism leaking to the outside of the magnetic gap (6), The magnetic flux can be concentrated.
【０００８】[0008]
【実施例】以下本考案の実施例について図面に基づいて
説明する。図中、図１及び図２は、本第１考案の１実施
例を示す図であって、図１はその縦断面図を、図２は図
１の実施例の磁力線の流れを示す縦断面図である。DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 are views showing one embodiment of the first invention, FIG. 1 is a longitudinal sectional view thereof, and FIG. 2 is a longitudinal sectional view showing a flow of magnetic field lines in the embodiment of FIG. FIG.
【０００９】本第１考案は、内磁型磁気回路において、
上部プレート(2c)の上端部(2d)に穿設した中心穴(2e)の
内側面(2h)に、 上部プレート(2c)と略厚さを等しくした
直円環状の副磁石(4)を嵌入して保持し、 前記副磁石(4)
の中心穴の内側面を、 磁気空隙(6)の外側面(6e)として
形成し、 主磁石(3)の磁路方向に直列に副磁石(4)を挿入
装着して、 該磁石(4)を半径方向に着磁したスピーカ用
磁気回路(5)である。The first device of the present invention relates to an inner magnet type magnetic circuit,
At the inner surface (2h) of the center hole (2e) drilled at the upper end (2d) of the upper plate (2c), a right circular sub-magnet (4) approximately equal in thickness to the upper plate (2c) is provided. The auxiliary magnet (4)
The inner surface of the center hole is formed as the outer surface (6e) of the magnetic air gap (6), and the sub magnet (4) is inserted and mounted in series in the magnetic path direction of the main magnet (3). ) Is a speaker magnetic circuit (5) magnetized in the radial direction.
【００１０】第２考案は、第１考案を変形した構造であ
って、図３に示すように、前記の副磁石(4)を嵌入して
保持した、 上部プレート(2c)の上面が、 副磁石(4)の上
面を含めて、 センタポール(1)の上面(1a)より少なくと
も(Ｄ)以上高く位置せしめた第１考案相当のスピーカ用
磁気回路(5')である。ここにＤ＞０の関係式が成立す
る。The second invention is a modified structure of the first invention. As shown in FIG. 3, the upper surface of the upper plate (2c) in which the above-mentioned sub-magnet (4) is fitted and held, A magnetic circuit (5 ') for a speaker according to the first invention, which is located at least (D) higher than the upper surface (1a) of the center pole (1), including the upper surface of the magnet (4). Here, the relational expression of D> 0 holds.
【００１１】以上本考案の代表的と思われる実施例につ
いて説明したが、本考案は必ずしもこれらの実施例構造
のみに限定されるものではなく、本考案にいう前記の構
成要件を備え、かつ、本考案にいう目的を達成し、以下
にいう効果を有する範囲内において適宜改変して実施す
ることができるものである。Although the embodiments which are considered to be representative of the present invention have been described above, the present invention is not necessarily limited only to the structure of the embodiments, but has the above-mentioned constitutional requirements according to the present invention, and The present invention achieves the object of the present invention and can be appropriately modified and implemented within a range having the following effects.
【００１２】[0012]
【考案の効果】以上の説明から既に明らかなように、本
考案は、このような構造としたものであるから、主磁石
には従来の例えばアルニコ磁石を使用して、副磁石(4)
として磁路の一部に使用することによって、主磁石によ
る磁気回路の性能発揮と、 異方性磁石(4)の起磁力を利
用して、 磁気空隙(6)の外部に漏れる漏洩磁気を少なく
して、 主、 副両磁石(3),(4)の使用効率を高めて、 磁石
のスペースファクタの向上を図ることを目的とし、磁気
空隙の磁束密度を飛躍的に向上させて、 小形で、 強力、
かつ高能率なスピーカに適した磁気回路(5)となる。従来
例と本願考案との磁気回路の漏洩磁束の比較を、 磁気空
隙のレラクタンスの比較から計算すると、次ぎの表１の
ようになる。[Effects of the Invention] As is apparent from the above description, the present invention has such a structure. Therefore, a conventional magnet such as an alnico magnet is used as the main magnet, and the auxiliary magnet (4) is used.
As a part of the magnetic path, the performance of the magnetic circuit by the main magnet and the use of the magnetomotive force of the anisotropic magnet (4) to reduce leakage magnetism leaking outside the magnetic air gap (6) The purpose is to increase the efficiency of use of the main and sub magnets (3) and (4) and to improve the space factor of the magnets. , Powerful,
And a magnetic circuit (5) suitable for a highly efficient speaker. The following Table 1 shows a comparison of the leakage flux of the magnetic circuit between the conventional example and the present invention based on the comparison of the reluctance of the magnetic air gap.
【００１３】[0013]
【表１】 [Table 1]
【００１４】従来例と本願考案との磁気回路側面の近傍
を、 磁気回路の軸と平行な方向に沿って測定した漏洩磁
束の実数比較は、図４，図５に示すとおりであって、横
軸に磁気回路(原点０)からの距離を取り、縦軸にその点
からの磁束密度の絶対値を示す。 測定位置は、図５に
示すとおりである。これらから見られるように、本考案
実施例は従来例に対し、 １５〜２３％漏洩磁束が少な
く、有効に作用して効果が現出している。即ち、図４の
従来例と本願考案の実施例のカーブの上下の開きの大き
な箇所が漏洩磁束の差が大きなところである。これか
ら、磁気回路外側の原点Ｏ点から２cmの測定点が、 最も
差が大きくなっている。A comparison of the real numbers of the leakage magnetic flux measured in the direction parallel to the axis of the magnetic circuit between the conventional example and the side of the magnetic circuit of the present invention is as shown in FIGS. The axis indicates the distance from the magnetic circuit (origin 0), and the axis of ordinate indicates the absolute value of the magnetic flux density from that point. The measurement positions are as shown in FIG. As can be seen from the above, the embodiment of the present invention has a smaller leakage magnetic flux by 15 to 23% than the conventional example, and works effectively to show the effect. That is, the difference between the leakage magnetic flux is large in the conventional example shown in FIG. From this, the difference is largest at the measurement point 2 cm from the origin O point outside the magnetic circuit.
【００１５】図６に示す図は、従来例と本考案実施例の
磁気空隙に発生する磁束密度の比較であり、横軸に磁気
空隙上端部(０)からの距離を、 縦軸に磁束密度の絶対値
を表す。これから見られるように、磁気空隙の中央付近
で本考案で10,200ガウス、 従来例で8,000ガウスとなり、
実施例は従来例に対して２４％程度向上している。第
２考案は、図３に示すように、請求項１に記載のスピー
カ用磁気回路の変形であって、前記の副磁石(4)を嵌入
して保持した、 上部プレート(2c)の上面が、磁石(4)の上
面を含めて、 センタポール(1)の上面(1a)より少なくと
も高く位置せしめた構造によって、センタポール(1)の
上面(1a)の角部の、 最も磁束の集中する箇所が、 副磁石
(4)の磁気空隙(6)の中腹部に対向するので、 磁束が下方
へ引き込まれて、 その漏洩率が減少し、磁気空隙の磁束
密度の増加効果は更に向上する。FIG. 6 is a comparison of the magnetic flux density generated in the magnetic air gap between the conventional example and the embodiment of the present invention. The horizontal axis indicates the distance from the upper end (0) of the magnetic air gap, and the vertical axis indicates the magnetic flux density. Represents the absolute value of As can be seen, near the center of the magnetic air gap, the present invention is 10,200 gauss, the conventional example is 8,000 gauss,
The embodiment is improved by about 24% compared to the conventional example. The second invention is a modification of the magnetic circuit for a loudspeaker according to claim 1, as shown in FIG. 3, wherein the upper surface of the upper plate (2c) in which the auxiliary magnet (4) is fitted and held is formed. Due to the structure positioned at least higher than the upper surface (1a) of the center pole (1), including the upper surface of the magnet (4), the magnetic flux concentrates at the corners of the upper surface (1a) of the center pole (1). Where the secondary magnet
Since it faces the middle part of the magnetic gap (6) of (4), the magnetic flux is drawn downward, the leakage rate decreases, and the effect of increasing the magnetic flux density of the magnetic gap further improves.
【図１】本考案の１実施例を示した縦断面図。FIG. 1 is a longitudinal sectional view showing one embodiment of the present invention.
【図２】図１の本考案の実施例の磁力線の流れを示す縦
断面図。FIG. 2 is a longitudinal sectional view showing the flow of the magnetic field lines in the embodiment of the present invention in FIG. 1;
【図３】本考案の他の実施例の縦断面図。FIG. 3 is a longitudinal sectional view of another embodiment of the present invention.
【図４】磁気回路の側面漏洩磁束の比較図。FIG. 4 is a comparison diagram of the side leakage magnetic flux of the magnetic circuit.
【図５】図４の測定点の位置を示す図。FIG. 5 is a diagram showing positions of measurement points in FIG. 4;
【図６】磁気空隙内の磁束密度の比較図。FIG. 6 is a comparison diagram of a magnetic flux density in a magnetic gap.
【図７】従来例の縦断面図。FIG. 7 is a longitudinal sectional view of a conventional example.
【図８】従来例の磁力線の流れを示す縦断面図。FIG. 8 is a longitudinal sectional view showing a flow of lines of magnetic force of a conventional example.
(1) センタポール (1a) センタポール先端部 (2) 円筒形ヨーク (2a) 円筒形ヨーク側面部 (2b) 円筒形ヨーク下部内側面 (2c) 上部プレート (2d) 上端部 (2e) 中心穴 (2h) 内側面 (3) 主磁石 (4) 副磁石 (5) 磁気回路 (5') 磁気回路 (6) 磁気空隙 (6e) 磁気空隙外側面 (D) 差 (1) Center pole (1a) Center pole tip (2) Cylindrical yoke (2a) Cylindrical yoke side (2b) Cylindrical yoke lower inner side (2c) Upper plate (2d) Upper end (2e) Center hole (2h) Inner surface (3) Main magnet (4) Secondary magnet (5) Magnetic circuit (5 ') Magnetic circuit (6) Magnetic air gap (6e) Magnetic air gap outer surface (D) Difference
フロントページの続き (56)参考文献 特開 昭60−167309（ＪＰ，Ａ) 特開 昭51−54424（ＪＰ，Ａ) 特開 平１−300696（ＪＰ，Ａ) 実開 昭61−40175（ＪＰ，Ｕ) 実開 昭59−96994（ＪＰ，Ｕ) 実開 昭59−104697（ＪＰ，Ｕ) 実開 昭55−31386（ＪＰ，Ｕ) 実開 昭59−57095（ＪＰ，Ｕ) 実開 昭57−41607（ＪＰ，Ｕ) 特公 昭45−12105（ＪＰ，Ｂ１)Continuation of the front page (56) References JP-A-60-167309 (JP, A) JP-A-51-54424 (JP, A) JP-A-1-300696 (JP, A) Jpn. , U) Fully open sho 59-96994 (JP, U) Really open sho 59-104697 (JP, U) Really open sho 55-31386 (JP, U) Really open sho 59-57095 (JP, U) Real open sho 57-41607 (JP, U) JP-B-45-12105 (JP, B1)
Claims (2)
（２ｃ）の上端部（２ｄ）に穿設した中心穴（２ｅ）の
内側面（２ｈ）に、上部プレート（２ｃ）と略厚さを等
しくした直円環状の副磁石（４）を嵌入して保持し、前
記副磁石（４）の中心穴の内側面を、磁気空隙（６）の
外側面（６ｅ）として形成し、主磁石（３）の磁路方向
に直列に副磁石（４）を挿入装着して、該副磁石（４）
を半径方向に着磁したスピーカ用磁気回路。In the internal magnetic type magnetic circuit, the thickness of the upper plate (2c) is substantially the same as that of the upper plate (2c) on the inner surface (2h) of the center hole (2e) formed in the upper end (2d) of the upper plate (2c). The sub-magnet (4) having the same straight annular shape is fitted and held, and the inner surface of the center hole of the sub-magnet (4) is formed as the outer surface (6e) of the magnetic gap (6). 3) the sub magnet (4) in series in the direction of the magnetic path by inserting mounting of the auxiliary magnet (4)
Is a magnetic circuit for a speaker that is magnetized radially.
た、上部プレート（２ｃ）の上面を、副磁石（４）の上
面を含めて、センタポール（１）の上面（１ａ）よりも
高い位置に配置した請求項１に記載のスピーカ用磁気回
路。2. A were held by fitting the said auxiliary magnet (4), the upper surface of the upper plate (2c), including the upper surface of the auxiliary magnet (4), the upper surface of the center pole (1) (1a) Also
The magnetic circuit for a speaker according to claim 1, wherein the magnetic circuit is arranged at a high position .
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP9145591U JP2568241Y2 (en) | 1991-10-11 | 1991-10-11 | Magnetic circuit for speaker |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP9145591U JP2568241Y2 (en) | 1991-10-11 | 1991-10-11 | Magnetic circuit for speaker |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0534797U JPH0534797U (en) | 1993-05-07 |
| JP2568241Y2 true JP2568241Y2 (en) | 1998-04-08 |
Family
ID=14026846
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP9145591U Expired - Lifetime JP2568241Y2 (en) | 1991-10-11 | 1991-10-11 | Magnetic circuit for speaker |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2568241Y2 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US11184712B2 (en) | 2015-05-19 | 2021-11-23 | Bose Corporation | Dual-field single-voice-coil transducer |
| US11245986B2 (en) | 2019-10-24 | 2022-02-08 | Bose Corporation | Electro-magnetic motor geometry with radial ring and axial pole magnet |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2006080405A1 (en) * | 2005-01-28 | 2006-08-03 | Matsushita Electric Industrial Co., Ltd. | Electrokinetic electro-acoustic converter and electronic device |
| JP2007281869A (en) * | 2006-04-06 | 2007-10-25 | Fujitsu Ten Ltd | Speaker magnetic circuit |
| JP4661666B2 (en) * | 2006-04-07 | 2011-03-30 | パナソニック株式会社 | Speaker and electronic device using it |
| EP1928208B1 (en) * | 2006-09-29 | 2012-08-01 | Panasonic Corporation | Speaker and electronic equipment utilizing the same |
-
1991
- 1991-10-11 JP JP9145591U patent/JP2568241Y2/en not_active Expired - Lifetime
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US11184712B2 (en) | 2015-05-19 | 2021-11-23 | Bose Corporation | Dual-field single-voice-coil transducer |
| US11245986B2 (en) | 2019-10-24 | 2022-02-08 | Bose Corporation | Electro-magnetic motor geometry with radial ring and axial pole magnet |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0534797U (en) | 1993-05-07 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US7477757B2 (en) | Dual-gap transducer with radially-charged magnet | |
| US7065225B2 (en) | Electromagnetic transducer having a low reluctance return path | |
| US20040131223A1 (en) | Electromagnetic transducer having a hybrid internal/external magnet motor geometry | |
| US5550332A (en) | Loudspeaker assembly | |
| JP2568241Y2 (en) | Magnetic circuit for speaker | |
| JPH0543697U (en) | Magnetic circuit for speaker | |
| JP2558095Y2 (en) | Magnetic circuit for speaker | |
| JP2607796Y2 (en) | Magnetic circuit for speaker | |
| US3549830A (en) | Magnet configuration for a loudspeaker | |
| JP4594562B2 (en) | Magnetic circuit of speaker | |
| JP2549167Y2 (en) | Magnetic circuit for speaker | |
| JP2600135B2 (en) | Speaker | |
| JP2000358296A (en) | Speaker and speaker device | |
| JPS5931110Y2 (en) | electrodynamic speaker | |
| JP3195520B2 (en) | Repulsion magnetic circuit type speaker | |
| JPS6311822Y2 (en) | ||
| JPS5855742Y2 (en) | Magnetic circuit for speakers | |
| JPS5838713Y2 (en) | Magnetic circuit structure of permanent magnet for speaker | |
| JPH0413909Y2 (en) | ||
| JP3076591B2 (en) | Electrodynamic electroacoustic transducer | |
| JP2605427Y2 (en) | Magnetic circuit for speaker | |
| JPS6198098A (en) | Dynamic speaker | |
| JP2586418Y2 (en) | Magnetic circuit for speaker | |
| JPH0422637Y2 (en) | ||
| JP3053925U (en) | Magnetic circuit for speaker |