JPH0548679B2 - - Google Patents
Info
- Publication number
- JPH0548679B2 JPH0548679B2 JP59009001A JP900184A JPH0548679B2 JP H0548679 B2 JPH0548679 B2 JP H0548679B2 JP 59009001 A JP59009001 A JP 59009001A JP 900184 A JP900184 A JP 900184A JP H0548679 B2 JPH0548679 B2 JP H0548679B2
- Authority
- JP
- Japan
- Prior art keywords
- diaphragm
- whiskers
- carbon fiber
- montmorillonite
- molding
- 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
- 229920000049 Carbon (fiber) Polymers 0.000 claims description 21
- 239000004917 carbon fiber Substances 0.000 claims description 21
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims description 16
- 239000003795 chemical substances by application Substances 0.000 claims description 12
- GUJOJGAPFQRJSV-UHFFFAOYSA-N dialuminum;dioxosilane;oxygen(2-);hydrate Chemical compound O.[O-2].[O-2].[O-2].[Al+3].[Al+3].O=[Si]=O.O=[Si]=O.O=[Si]=O.O=[Si]=O GUJOJGAPFQRJSV-UHFFFAOYSA-N 0.000 claims description 10
- 229910052901 montmorillonite Inorganic materials 0.000 claims description 10
- 239000002131 composite material Substances 0.000 claims description 9
- 239000000203 mixture Substances 0.000 claims description 8
- 238000000465 moulding Methods 0.000 claims description 7
- 229920005989 resin Polymers 0.000 claims description 7
- 239000011347 resin Substances 0.000 claims description 7
- 239000000463 material Substances 0.000 claims description 6
- 239000000178 monomer Substances 0.000 claims description 5
- 229920001187 thermosetting polymer Polymers 0.000 claims description 5
- 239000003822 epoxy resin Substances 0.000 claims description 4
- 229920000647 polyepoxide Polymers 0.000 claims description 4
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical class [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 claims description 3
- 229910052581 Si3N4 Inorganic materials 0.000 claims description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 2
- NJLLQSBAHIKGKF-UHFFFAOYSA-N dipotassium dioxido(oxo)titanium Chemical compound [K+].[K+].[O-][Ti]([O-])=O NJLLQSBAHIKGKF-UHFFFAOYSA-N 0.000 claims description 2
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 claims description 2
- 238000010438 heat treatment Methods 0.000 claims 1
- 239000000835 fiber Substances 0.000 description 4
- 238000001746 injection moulding Methods 0.000 description 4
- 229920000642 polymer Polymers 0.000 description 3
- -1 polypropylene Polymers 0.000 description 3
- 239000004593 Epoxy Substances 0.000 description 2
- 239000004743 Polypropylene Substances 0.000 description 2
- 239000004744 fabric Substances 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 239000005011 phenolic resin Substances 0.000 description 2
- 230000000704 physical effect Effects 0.000 description 2
- 229920001155 polypropylene Polymers 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- KXGFMDJXCMQABM-UHFFFAOYSA-N 2-methoxy-6-methylphenol Chemical compound [CH]OC1=CC=CC([CH])=C1O KXGFMDJXCMQABM-UHFFFAOYSA-N 0.000 description 1
- RIAHASMJDOMQER-UHFFFAOYSA-N 5-ethyl-2-methyl-1h-imidazole Chemical compound CCC1=CN=C(C)N1 RIAHASMJDOMQER-UHFFFAOYSA-N 0.000 description 1
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 1
- 229920003319 Araldite® Polymers 0.000 description 1
- MQJKPEGWNLWLTK-UHFFFAOYSA-N Dapsone Chemical compound C1=CC(N)=CC=C1S(=O)(=O)C1=CC=C(N)C=C1 MQJKPEGWNLWLTK-UHFFFAOYSA-N 0.000 description 1
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 description 1
- LGRFSURHDFAFJT-UHFFFAOYSA-N Phthalic anhydride Natural products C1=CC=C2C(=O)OC(=O)C2=C1 LGRFSURHDFAFJT-UHFFFAOYSA-N 0.000 description 1
- YKTSYUJCYHOUJP-UHFFFAOYSA-N [O--].[Al+3].[Al+3].[O-][Si]([O-])([O-])[O-] Chemical compound [O--].[Al+3].[Al+3].[O-][Si]([O-])([O-])[O-] YKTSYUJCYHOUJP-UHFFFAOYSA-N 0.000 description 1
- 229910000278 bentonite Inorganic materials 0.000 description 1
- 239000000440 bentonite Substances 0.000 description 1
- SVPXDRXYRYOSEX-UHFFFAOYSA-N bentoquatam Chemical compound O.O=[Si]=O.O=[Al]O[Al]=O SVPXDRXYRYOSEX-UHFFFAOYSA-N 0.000 description 1
- JHIWVOJDXOSYLW-UHFFFAOYSA-N butyl 2,2-difluorocyclopropane-1-carboxylate Chemical compound CCCCOC(=O)C1CC1(F)F JHIWVOJDXOSYLW-UHFFFAOYSA-N 0.000 description 1
- ZZTCPWRAHWXWCH-UHFFFAOYSA-N diphenylmethanediamine Chemical compound C=1C=CC=CC=1C(N)(N)C1=CC=CC=C1 ZZTCPWRAHWXWCH-UHFFFAOYSA-N 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 239000002655 kraft paper Substances 0.000 description 1
- 238000002386 leaching Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000155 melt Substances 0.000 description 1
- 239000006082 mold release agent Substances 0.000 description 1
- 239000004745 nonwoven fabric Substances 0.000 description 1
- 229920001568 phenolic resin Polymers 0.000 description 1
- 238000007493 shaping process Methods 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 229920005992 thermoplastic resin Polymers 0.000 description 1
- 238000007666 vacuum forming Methods 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
- 239000002759 woven fabric Substances 0.000 description 1
- XOOUIPVCVHRTMJ-UHFFFAOYSA-L zinc stearate Chemical compound [Zn+2].CCCCCCCCCCCCCCCCCC([O-])=O.CCCCCCCCCCCCCCCCCC([O-])=O XOOUIPVCVHRTMJ-UHFFFAOYSA-L 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R7/00—Diaphragms for electromechanical transducers; Cones
- H04R7/02—Diaphragms for electromechanical transducers; Cones characterised by the construction
Landscapes
- Engineering & Computer Science (AREA)
- Multimedia (AREA)
- Physics & Mathematics (AREA)
- Acoustics & Sound (AREA)
- Signal Processing (AREA)
- Diaphragms For Electromechanical Transducers (AREA)
Description
この発明は電気音響変換器用振動板の改良に関
し、特に剛性が高く、成形が非常に容易なる材料
より構成された振動板に関する。
近年、電気音響変換器用振動板において主とし
て剛性を増す目的から振動板構成材料の一部材と
してカーボン繊維を用いたものが考えられ、かつ
実用に供されている。
この種の振動板を例示すると
(1) カーボン繊維とバルブ繊維を混抄した後、フ
エノール樹脂等を用いて賦形した振動板
(2) ポリプロピレン樹脂等の熱可塑性樹脂にカー
ボン繊維を混合してシート成形し、これを真空
成形した振動板、又は上記材料を混合して射出
成形した振動板
(3) カーボン繊維の織布又は不織布に熱硬化性樹
脂を含浸してプレプレグとし、これをプレス成
形した振動板
等が実用化されている。
しかるに、上記従来の振動板は種々の欠点を有
している。
たとえば(1)においてはカーボン繊維の特徴であ
る高弾性特性が充分に生かされず50wt％カーボ
ン繊維混入量でもヤング率はせいぜい５×
1010dyn／cmである。
これはカーボン繊維とパルプ繊維の混合率に対
するヤング率にピーク値が生じ、カーボン繊維の
混合率に制限があるためである。
又、(2)においてはシート成形時における混合物
の流動性、吐出ノズルの寸法からカーボン繊維混
入量が制限を受ける。
たとえば、0.3〜0.5mm厚のシートではカーボン
繊維の混合量はせいぜい20wt％である。
また、上記混合量は真空成形工程からの制限も
受ける。
一方、射出成形では上記混合量はせいぜい
15wt％である。
したがつて、振動板の剛性を充分に上げること
ができない。
更に(3)は上記２例から比べると剛性の高い振動
板が得られるが、一旦織布として組織化された一
枚の平らな布をコーン状又はドーム状に成形する
にはカーボン繊維自体の伸縮が奇態できない以上
織目ズレを利用して賦形しなければならないの
で、予備成形等の数々の工程を経て賦形が可能と
なるため製造コストが極めて高く、又頂角の大き
い形状やコルゲーシヨンリブの一体成形等の複雑
な形状の振動板が成形困難であつた。
そこでこの発明では硬化剤又は硬化促進剤を層
間に吸着せしめたモンモリロナイトと熱硬化性樹
脂モノマーとカーボン繊維を主要材料とする複合
材料とウイスカーとの混合物を加熱成形すること
により物性の優れた振動板を提供すると共に成形
を容易にしたものであり、以下実施例について詳
細に説明する。
この発明の目的には硬化剤又は硬化促進剤を層
間に吸着せしめた含水アルミケイ酸塩の一種であ
るモンモリロナイト（Al2O3・4Si2O・nH2O、別
名ベントナイト）が重要である。
当該モンモリロナイトを硬化剤又は硬化促進剤
を適当な溶剤に溶かした溶液中に（60℃、数時
間）浸漬する。
これによつてモンモリロナイトのシリケート層
間に硬化剤又は硬化促進剤が吸着される。
これを溶液洗浄した後、乾燥せしめて硬化剤又
は硬化促進剤との複合体を得る。
次に当該複合体を用いたこの発明振動板の実施
例について説明する。
［実施例］
複合体（硬化剤としてジアミノジフエニールメタ
ン吸着） 10部
エポキシ樹脂モノマー（商品名アラルダイト
6071） 30部
硬化剤（ジアミノジフエニールスルホン） 4.4部
離型剤（ステアリン酸亜鉛） １部
カーボン繊維（ポリアクニロニトリル系カーボン
繊維 平均長0.35mm） 45部
上記配合物を加温下（85℃）で撹拌して均一に
配合し、しかる後に冷却せしめて粉砕し粉末状の
複合材料を得た。
当該複合材料にシリコンカーバイドウイスカー
（繊維径0.2〜0.5μｍ）10部を均一に混合して所定
形状の金型により温度160℃、プレス圧85Kg／cm2、
成形時間10分でプレス成形してコーン型振動板を
得た。
上記実施例で得られた振動板とカーボン繊維を
用いた従来の振動板として
従来例 １
クラフトパルプ50wt％、カーボン繊維35wt％、
フエノール樹脂15wt％よりなる振動板。
従来例 ２
ポリプロピレン樹脂に15wt％のカーボン繊維
を混合し射出成形してなる振動板。
との物性（密度ρ、ヤング率Ｅ）を測定した結果
を下表に示す。
The present invention relates to an improvement in a diaphragm for an electroacoustic transducer, and particularly to a diaphragm made of a material that has high rigidity and is extremely easy to mold. In recent years, diaphragms for electroacoustic transducers using carbon fiber as a component of the diaphragm have been considered and put into practical use primarily for the purpose of increasing rigidity. Examples of this type of diaphragm are: (1) A diaphragm made by mixing carbon fiber and valve fiber and then shaping it using phenol resin, etc. (2) A sheet made by mixing carbon fiber with a thermoplastic resin such as polypropylene resin. A diaphragm that is molded and vacuum-formed, or a diaphragm that is injection-molded by mixing the above materials (3) Carbon fiber woven or non-woven fabric is impregnated with a thermosetting resin to make a prepreg, which is then press-molded. Vibration plates and the like have been put into practical use. However, the conventional diaphragm described above has various drawbacks. For example, in (1), the high elasticity characteristic of carbon fiber is not fully utilized, and even if the amount of carbon fiber mixed is 50 wt%, the Young's modulus is at most 5 ×
10 10 dyn/cm. This is because a peak value occurs in Young's modulus with respect to the mixing ratio of carbon fibers and pulp fibers, and there is a limit to the mixing ratio of carbon fibers. In addition, in (2), the amount of carbon fiber mixed is limited by the fluidity of the mixture during sheet forming and the dimensions of the discharge nozzle. For example, in a sheet with a thickness of 0.3 to 0.5 mm, the amount of carbon fiber mixed is at most 20 wt%. Further, the above mixing amount is also limited by the vacuum forming process. On the other hand, in injection molding, the above mixing amount is at most
It is 15wt%. Therefore, the rigidity of the diaphragm cannot be increased sufficiently. Furthermore, in (3), a diaphragm with higher rigidity can be obtained compared to the above two examples, but in order to form a flat cloth into a cone or dome shape once organized as a woven cloth, the carbon fiber itself must be formed. Since it is impossible to stretch or contract, it is necessary to take advantage of the misalignment of the weave to form the shape, so the manufacturing cost is extremely high because the shape can be formed through a number of processes such as preforming. It was difficult to mold a diaphragm with a complicated shape, such as one-piece molding of gagement ribs. Therefore, in this invention, a diaphragm with excellent physical properties is achieved by heat-forming a mixture of whiskers and a composite material whose main materials are montmorillonite with a curing agent or curing accelerator adsorbed between the layers, a thermosetting resin monomer, and carbon fiber. The present invention provides the following advantages and facilitates molding.Examples will be described in detail below. For the purpose of this invention, montmorillonite (Al 2 O 3 .4Si 2 O.nH 2 O, also known as bentonite), which is a type of hydrous aluminum silicate in which a curing agent or a curing accelerator is adsorbed between layers, is important. The montmorillonite is immersed (60° C., several hours) in a solution of a hardening agent or hardening accelerator in a suitable solvent. As a result, the curing agent or curing accelerator is adsorbed between the silicate layers of montmorillonite. After solution washing, this is dried to obtain a composite with a curing agent or curing accelerator. Next, an example of the diaphragm of the present invention using the composite will be described. [Example] Composite (diaminodiphenylmethane adsorption as curing agent) 10 parts Epoxy resin monomer (trade name: Araldite)
6071) 30 parts hardening agent (diaminodiphenylsulfone) 4.4 parts mold release agent (zinc stearate) 1 part carbon fiber (polyacnylonitrile carbon fiber average length 0.35 mm) 45 parts The above mixture was heated ( The mixture was mixed uniformly by stirring at 85° C.), then cooled and pulverized to obtain a powdered composite material. 10 parts of silicon carbide whiskers (fiber diameter 0.2 to 0.5 μm) were uniformly mixed into the composite material and molded using a mold of a predetermined shape at a temperature of 160°C and a press pressure of 85 kg/cm 2 .
A cone-shaped diaphragm was obtained by press molding in 10 minutes. Conventional example 1: 50wt% kraft pulp, 35wt% carbon fiber,
A diaphragm made of 15wt% phenolic resin. Conventional example 2 A diaphragm made by injection molding a mixture of polypropylene resin and 15wt% carbon fiber. The results of measuring the physical properties (density ρ, Young's modulus E) are shown in the table below.
【表】
表から明らかなようにこの発明による振動板は
Ｅ／ρが極めて高いことが分る。
この発明の振動板のヤング率が著しく上昇する
要因としては、カーボン繊維およびウイスカーの
空間を埋めるようにモンモリロナイト−エポキシ
複合体が分散し、かつモンモリロナイトの層間に
入り込んだエポキシポリマーとモンモリロナイト
が強固に結合されたブレンド形ポリマーが形成さ
れ、当該ブレンド形ポリマーがカーボン繊維およ
びクイスカーをからみ込むように３次元網状構造
に組織化され、かつ繊維径の大きいカーボン繊維
間の隙間を繊維計の小さいウイスカーが分散配置
される為であると思われる。
又、この発明の振動板はプレス金型内において
エポキシ樹脂が一旦溶融し低粘度となつて流動す
るが、一定温度（150℃）まではモンモリロナイ
トの層間に吸着された硬化剤又は硬化促進剤が浸
出しないので低粘度の流動状態を保持する結果、
複雑な形状の金型であつても隅々まで充填され形
状寸法精度の高い振動板を得することができた。
従来のエポキシ樹脂、硬化剤混合体を成形する
場合硬化がただちに開始されるので短時間の成形
しか行なえず、又金型の隅々まで充填することが
困難であり、射出成形等が不可能であつたのに対
し、この発明によればこれらの欠点を解消し射出
成形による振動板の成形も可能となる。
なお上記実施例ではウイスカーとしてシリコン
カーバイドウイスカーを使用した場合について述
べたが、この発明に使用できる他のウイスカーと
してチタン酸カリウムウイスカー、窒化ケイ素ウ
イスカーおよびアルミナウイスカー等の１種もし
くは２種以上の組み合わせで使用できる。
又、モンモリロナイトに吸着させる硬化促進剤
としては、たとえばエチルメチルイミダゾールが
無水フタル酸（硬化剤）との組み合わせで使用で
きる。
以上に説明したように、この発明は硬化剤又は
硬化促進剤を層間に吸着せしめたモンモリロナイ
トと熱硬化性樹脂モノマーとカーボン繊維を主要
材料とする複合材料とウイスカーを主要材料と
し、上記材料の混合物を加熱成形してなることを
特徴とする電気音響変換器用振動板であつて、振
動板の高剛性化もしくは軽量化することができる
ので良好な周波数特性を有するスピーカーを提供
することができる。
尚、この発明をコーン型振動板に適用した場合
について述べたが勿論ドーム型振動板、更にはセ
ンタードームラジエーターにも適用することがで
きるものである。[Table] As is clear from the table, the diaphragm according to the present invention has an extremely high E/ρ. The reason why the Young's modulus of the diaphragm of this invention increases significantly is that the montmorillonite-epoxy composite is dispersed to fill the spaces between the carbon fibers and whiskers, and the epoxy polymer and montmorillonite that have entered between the layers of montmorillonite are strongly bonded. A blended polymer is formed, and the blended polymer is organized into a three-dimensional network structure so as to entangle carbon fibers and whiskers, and whiskers with small fiber diameters are dispersed in the gaps between carbon fibers with large diameters. This seems to be due to the placement. In addition, in the diaphragm of the present invention, the epoxy resin once melts in the press mold and becomes low in viscosity and flows, but up to a certain temperature (150°C), the curing agent or curing accelerator adsorbed between the layers of montmorillonite is As a result of no leaching, it maintains a low viscosity fluid state.
Even if the mold had a complicated shape, it was possible to obtain a diaphragm that was filled to every corner and had high shape and size accuracy. When molding conventional epoxy resin and curing agent mixtures, curing starts immediately, so molding can only be done for a short time, and it is difficult to fill every corner of the mold, making injection molding impossible. However, according to the present invention, these drawbacks can be overcome and the diaphragm can also be formed by injection molding. In the above embodiments, silicon carbide whiskers were used as the whiskers, but other whiskers that can be used in this invention include potassium titanate whiskers, silicon nitride whiskers, and alumina whiskers, or a combination of two or more of them. Can be used. Further, as a curing accelerator to be adsorbed to montmorillonite, for example, ethylmethylimidazole can be used in combination with phthalic anhydride (hardening agent). As explained above, the present invention uses a composite material mainly composed of montmorillonite, a thermosetting resin monomer, and carbon fiber with a curing agent or curing accelerator adsorbed between the layers, and whiskers as the main materials, and a mixture of the above materials. This is a diaphragm for an electroacoustic transducer characterized by being formed by heat-molding the diaphragm, and since the diaphragm can be made highly rigid or lightweight, it is possible to provide a speaker with good frequency characteristics. Although the present invention has been described as being applied to a cone-shaped diaphragm, it can of course also be applied to a dome-shaped diaphragm, and furthermore to a center dome radiator.
Claims (1)
モンモリロナイトと熱硬化性樹脂モノマーとカー
ボン繊維を主要材料とする複合材料とウイスカー
との混合物を加熱成形してなることを特徴とする
電気音響変換器用振動板。 ２ 熱硬化性樹脂モノマーがエポキシ樹脂である
ことを特徴とする特許請求の範囲第１項記載の電
気音響変換器用振動板。 ３ ウイスカーがシリコンカーバイドウイスカ
ー、チタン酸カリウムウイスカー、窒化ケイ素ウ
イスカー、及びアルミナウイスカーから選ばれた
１種又は２種以上の組み合わせであることを特徴
とする特許請求の範囲の第１項記載の電気音響変
換器用振動板。[Claims] 1. It is characterized by being formed by heating and molding a mixture of whiskers and a composite material whose main materials are montmorillonite with a curing agent or curing accelerator adsorbed between the layers, a thermosetting resin monomer, and carbon fiber. A diaphragm for electroacoustic transducers. 2. The diaphragm for an electroacoustic transducer according to claim 1, wherein the thermosetting resin monomer is an epoxy resin. 3. The electroacoustic device according to claim 1, wherein the whiskers are one or a combination of two or more selected from silicon carbide whiskers, potassium titanate whiskers, silicon nitride whiskers, and alumina whiskers. Transducer diaphragm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP900184A JPS60153299A (en) | 1984-01-21 | 1984-01-21 | Diaphragm for electroacoustic transducer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP900184A JPS60153299A (en) | 1984-01-21 | 1984-01-21 | Diaphragm for electroacoustic transducer |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS60153299A JPS60153299A (en) | 1985-08-12 |
| JPH0548679B2 true JPH0548679B2 (en) | 1993-07-22 |
Family
ID=11708430
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP900184A Granted JPS60153299A (en) | 1984-01-21 | 1984-01-21 | Diaphragm for electroacoustic transducer |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS60153299A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102200481A (en) * | 2010-03-23 | 2011-09-28 | 北京派科森科技有限公司 | Carbon Fiber Laminate Composite material used for Fiber Bragg Grating high voltage sensor |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5275316A (en) * | 1975-12-19 | 1977-06-24 | Mitsubishi Electric Corp | Diaphragm for speakers |
| JPS5351151U (en) * | 1976-10-04 | 1978-05-01 | ||
| JPS593689B2 (en) * | 1976-03-04 | 1984-01-25 | シ−メンス・アクチエンゲゼルシヤフト | Presetting device for flow measuring device |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS593689U (en) * | 1982-06-30 | 1984-01-11 | 株式会社ケンウッド | Diaphragm for speaker |
-
1984
- 1984-01-21 JP JP900184A patent/JPS60153299A/en active Granted
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5275316A (en) * | 1975-12-19 | 1977-06-24 | Mitsubishi Electric Corp | Diaphragm for speakers |
| JPS593689B2 (en) * | 1976-03-04 | 1984-01-25 | シ−メンス・アクチエンゲゼルシヤフト | Presetting device for flow measuring device |
| JPS5351151U (en) * | 1976-10-04 | 1978-05-01 |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS60153299A (en) | 1985-08-12 |
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