201018264 六、發明說明： 【發明所屬之技術領域】 本發明係關於將永久磁鐵與振動膜予以組合，而從音 1 頻訊號進行聲音再生之電磁轉換器。 【先前技術】 將永久磁鐵板與振動膜予以組合而構成之過去的電磁 轉換器，有使永久磁鐵板與振動膜相向配置，而且在永久 磁鐵板與振動膜之間配置缓衝材者。此等永久磁鐵板、振 動膜及緩衝材，係以夾在框架等的構件之間的方式受到包 © 覆，然後安裝在例如揚聲器的框體上。 上述的永久磁鐵板，具有隔著一定的間隔形成相互不 同的極性之帶狀的磁鐵部位（亦稱為多極著磁圖案）。此 外，振動膜係在與永久磁鐵板之相異極性的交界隔著某一 間隔而相向的位置，亦即所謂的著磁中性區域（neutral zone)，形成有蛇行線圈圖案者。當音頻訊號之電流在形成 於振動膜之蛇行線圈圖案流通時，蛇行線圈圖案就會與永 _ ❹ 久磁鐵的多極著磁圖案做電磁性結合，依弗來明定則 (Fleming’s rule)，電流作用於上述的蛇行線圈圖案，振 動膜就會振動。因該振動而產生的音波，通過穿設於永久 磁鐵板及框架之放射音孔向外部放射而進行音頻再生（參 照例如專利文獻1)。 另外，亦有基於防止形成於振動膜上之蛇行線圈圖案 的導體線圈在該振動之下因金屬疲勞而斷線之目的，而利 用剛性賦與構件來補強振動膜者（參照例如專利文獻2)。 4 321031 201018264 此外，一直以來，都有在與上述的電磁轉換器同樣的 構成中不用上述的永久磁鐵板而採用長條狀的棒狀磁鐵之 稱為「gamuzon(力、λ — y’、> )型」之薄型揚聲器存在。 garouzon型之薄型揚聲器，係在振動膜的表背兩侧配置將 相互不同極性的棒狀磁鐵並排而成的棒狀磁鐵板，將振動 膜夾在中間’且將隔著振動膜而相向之棒狀磁鐵的極配置 成相同（N極與N極、或S極與S極），除此之外的構件則 ❹為與上述的電磁轉換器相同的構件而構成者。 如此之薄型揚聲器具有：在由聚酯或聚醯亞胺形成之 薄膜貼附銅或鋁箔’然後蝕刻出音圈圖案（v〇ice c〇il pattern)而構成之振動膜（參照例如非專利文獻1)。此構 成之薄型揚聲器，其音頻再生之音波產生動作也與上述的 電磁轉換器相同。 專利文獻1 :日本專利第3192372號公報 專利文獻2 :國際公開W02003/073787號公報 ® 非專利文獻1 :山本武雄編著，只！£ 一力一一 〆入丁厶， 今夕才技術社，1977年7月發行 因為過去的電磁轉換器係以如上所述的方式構成，所 以有.使永久磁鐵著磁後，必須一邊注意一個個磁極的方 向一邊安裝至框架，使得作業效率變差之課題。 而且，必須在著磁、磁化後的狀態進行作業，鐵粉等 異物容易在作業過程中混入。因此，有：電磁轉換哭^為 異物混入而發出異音，使得當初設計的性能無法發=之f 題0 321031 5 201018264 本發明係為了解決如上述之課題而完成者，其目的在 提供可將未磁化狀態之永久磁鐵安裝至框架，等到電磁轉 換器組裝起來後再一併使所有的永久磁鐵著磁之電磁轉換 器。 【發明内容】 本發明之電磁轉換器，係具備有：表面設有放音孔之 中空的框架；表面成形有蛇行線圈圖案，且設置於框架的 内部之振動膜；以及以相錯開之模樣配置固定在隔著振動 膜而相向之框架的一對内壁面，且與固定的面相反側之相 對向的端面具有相互不同的磁性之複數個永久磁鐵者。 根據本發明，由於設計成具備有以相錯開之模樣配置 固定在框架的一對内壁面，且與固定的面相反側之相對向 的端面具有相互不同的磁性之複數個永久磁鐵，因此可將 未磁化狀態之永久磁鐵安裝至框架，等到電磁轉換器組裝 起來後再一併使所有的永久磁鐵著磁。因而，可削減著磁 處理的工序，提高組裝作業的效率。 【實施方式】 以下，為了更詳細說明本發明，茲針對實施本發明之 最佳的形態，根據隨附的圖式進行說明。 實施形態1 第1圖係顯示本發明之實施形態1的電磁轉換器10的 構造之外觀圖，第1圖（a)係外觀正面圖，第1圖（b)係外 觀侧面圖，第1圖（c)係外觀平面圖，第1圖（d)係外觀背 面圖。第1圖（a)及（b)中，以虛線表示收容於框架15的内 6 321031 201018264 部而實際上看不見之構造。 第2圖係顯示本發明之實施形態1的電磁轉換器10的 構造之剖面圖，第2圖（a)係沿著第1圖（a)所示的A-A線 切斷所見之剖面圖，第2圖（b)係沿著第1圖（a)所示的 B-B線切斷所見之剖面圖，第2圖（c)係沿著第1圖（a)所 示的C-C線切斷所見之剖面圖。第3圖係顯示本發明之實 施形態1的電磁轉換器10的振動膜11的外觀之斜視圖。 第1至第3圖係為了使說明簡單而誇張放大顯示之 〇 圖，與實際的比例會有出入。 電磁轉換器10係由上側框架16、永久磁鐵12、振動 膜11、永久磁鐵13、及下侧框架17所構成。上側框架16 及下侧框架17構成框架15，此框架15為内部中空的框體 構造。此處雖然為了方便而稱為上侧框架、下側框架，但 上下反過來也無妨。 上側框架16的内壁面，亦即與振動膜11相向的面， φ 以預定的間隔利用接著劑而固定有永久磁鐵12。下側框架 17的内壁面，亦即與振動膜11相向的面之與永久磁鐵12 相互之間的間隙相當之位置，利用接著劑而固定有複數列 永久磁鐵13。因此，如第2圖（a)之剖面圖所示，形成將 永久磁鐵12，13固定在上側框架16及下側框架17相錯開 的位置之交互錯開模樣之配置。 如第2圖（a)所示，固定於上側框架16之永久磁鐵12, 其固定於上侧框架16之端面係形成為N極，與振動膜11 相向的端面則形成為S極。另一方面，固定於下側框架17 7 321031 201018264 之永久磁鐵13，其固定於下側框架17之端面係形成為S 極，與振動膜11相向的端面則形成為N極。因此，永久磁 鐵12，13係為在與固定至框架的面相反側之相對向的端面 具有相互不同的極性之構成。 另外，上側框架16及下側框架17之未固定有永久磁 鐵12，13之部份，係以一定的間隔設有向外部開口之放音 孔 15a。 振動膜11係由薄的高分子材料的片狀基材11a所構 成。此基材11a係立體構造化為有著與永久磁鐵12, 13的 固定間隔相對應的寬度之凹凸形狀。此凹凸形狀係為沿著 永久磁鐵12，13的相對向的端面所構成的凹凸構造而成的 形狀。 振動膜11的表面，成形有形成為蛇行形狀之導體線圈 lib。導體線圈lib係對於銅或鋁之電性導體的箔進行蝕刻 或以衝壓機等進行衝切而成形。 振動膜11的外周面固定有振動膜支持材14，藉由將 此振動膜支持材14固定在下側框架17的内周，而將振動 膜11支持成可上下變位。如第2圖（a)所示，振動膜支持 材14將振動膜11固定在下側框架17之際，係進行對位以 使導體線圈lib位在永久磁鐵12, 13的端面彼此相對向之 高度的位置。 而且，基材11a的凹凸形狀，係成形成：當振動膜支 持材14所支持的振動膜11振動而上下變位時不會與永久 磁鐵12，13接觸，振動膜11與永久磁鐵12，13之間存在 8 321031 201018264 有空間之形狀。 另外，在振動膜11的表面及背面 ^ 動膜11的剛性而設有凸肋（rib)構、’為了提高振 補強構造部11c。 。或凹6構造之振動膜 ❹ ❹ 按者’針對水久磁與“，U的 首先’以在框架上的位置相錯方去進订說明。 將永久磁鐵12固定於上側框架16 乂互錯開松樣配！ 下侧框架17 ’再令振動膜u夾於”水久磁鐵13固定% 組裝起來。然後，對於組裝起來=將電磁轉換器1( 於上侧框架16及下侧框架17 轉換器10，在相詞 磁，使永久磁鐵12，13都以相垂直的方向進行同時Ϊ 永久磁鐵12, 13之相對向的極方向磁化。因此， 的極性。 ° ’曰形成相互不同之帶肤 接者針對電磁轉換器1〇的红 在第1圖及第2圖所示曾作原理進行說明。 將電流（音頻訊號）供給至振動礙轉換器10中，當從外部 永久磁鐵U的N極發出沾二、、11的導體線圈lib時，從 後到達永久磁鐵12的s極通就會與導體線圈llb正交而 12，13的磁通方向大致吉此時，在成形成與永久磁鐵 圈圖案上流通的電流會鱼、角之導體線圈llb的蛇行的絲 通密度）做電磁性的耦合、，水久礤鐵12，13的著磁圖案（培 生。在產生的驅動力作用下^據弗來明定則就會有驅動力產 動膜11會振動。此振動支持於振動膜支持材14的掘 15的放音孔15a放射會產生音頻再生音而從設於框架 321031 9 201018264 根據上述的實施形態1，因為形成：使振動膜丨1成形 為凹凸形狀’使永久磁鐵12’ 13排列成位置相錯的千烏纹 樣配置，且使永久磁鐵12的磁極方向與永久磁鐵13的磁 極方向相同之構成，所以町在電磁轉換器10的組裝後再一 併使永久磁鐵12，13著磁。因此’可削減如同在過去的 gamuzon型揚聲器中之先讓永久磁鐵著磁後一邊注意一個 個磁極的方向一邊安裝至桩架之作業，可提高組裝作業效 率。 而且，因為在電磁轉換器10的組裝後進行著磁，所以 ❹ 在組裝作業中不會有鐵粉等異物混入之情形。因此，可防 止電磁轉換器1〇中有異音產生而無法發揮當初設計的性 · 能之問題，且可簡易地製造高品質的電磁轉換器1 〇。 此外’導體線圈llb町在基材11a的一側面成形，亦 可如第2圖（a)所示般在基材11a的表背兩面成形。在表背 兩面成形之情況，可更忠實地將音頻訊號轉換為音頻再生 音。201018264 VI. Description of the Invention: [Technical Field] The present invention relates to an electromagnetic converter that combines a permanent magnet and a diaphragm to perform sound reproduction from a tone 1 signal. [Prior Art] In the conventional electromagnetic converter in which a permanent magnet plate and a diaphragm are combined, a permanent magnet plate and a diaphragm are disposed to face each other, and a cushioning material is disposed between the permanent magnet plate and the diaphragm. These permanent magnet plates, vibrating membranes, and cushioning materials are covered by a cover so as to be sandwiched between members such as a frame, and then mounted on a casing such as a speaker. The above permanent magnet plate has a strip-shaped magnet portion (also referred to as a multipolar magnetic pattern) having mutually different polarities formed at regular intervals. Further, the vibrating membrane is formed at a position opposite to the boundary of the permanent magnet plates at a certain interval, that is, a so-called neutral neutral zone, and a serpentine coil pattern is formed. When the current of the audio signal circulates in the serpentine coil pattern formed on the vibrating membrane, the serpentine coil pattern is electromagnetically combined with the multipole magnetic pattern of the permanent magnet, Fleming's rule, current When the snake coil pattern is applied to the above, the diaphragm vibrates. The sound waves generated by the vibration are radiated to the outside through the radio sound holes that are bored in the permanent magnet plate and the frame (see, for example, Patent Document 1). In addition, the conductor coil for preventing the meandering coil pattern formed on the vibrating film is broken by metal fatigue under the vibration, and the vibrating membrane is reinforced by the rigid imparting member (see, for example, Patent Document 2) . 4 321031 201018264 In addition, in the same configuration as the above-described electromagnetic converter, a long rod-shaped magnet is used instead of the above-described permanent magnet plate, and it is called "gamuzon (force, λ - y', > The thin type speaker of the ") type exists. The garouzon type thin speaker is a rod-shaped magnet plate in which rod magnets of different polarities are arranged side by side on the front and back sides of the vibrating membrane, and the vibrating membrane is sandwiched between the vibrating membranes and the diaphragm is opposed to each other. The poles of the magnets are arranged in the same order (N pole and N pole, or S pole and S pole), and the other members are the same members as the above-described electromagnetic converter. Such a thin speaker has a diaphragm in which a copper or aluminum foil is attached to a film formed of polyester or polyimide, and then a voice coil pattern is etched (see, for example, Non-Patent Literature). 1). In the thin speaker constructed as described above, the sound generation operation of the audio reproduction is also the same as that of the above-described electromagnetic converter. Patent Document 1: Japanese Patent No. 3192372 (Patent Document 2: International Publication No. WO2003/073787) Non-Patent Document 1: Edited by Yamamoto Takeo, only! £ 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一 一When the direction of the magnetic pole is attached to the frame, the work efficiency is deteriorated. In addition, it is necessary to work in a state of being magnetized or magnetized, and foreign matter such as iron powder is likely to be mixed during the work. Therefore, there is: electromagnetic conversion crying ^ for the foreign matter mixed in and emits an abnormal sound, so that the performance of the original design can not be issued = f 0 0103103 1 5 201018264 The present invention has been completed in order to solve the problems as described above, the purpose of which is to provide The permanent magnets in the unmagnetized state are mounted to the frame, and after the electromagnetic converter is assembled, the permanent magnets are magnetized. SUMMARY OF THE INVENTION An electromagnetic converter according to the present invention includes: a hollow frame having a sound-emitting hole on its surface; a vibrating film having a serpentine coil pattern formed on the surface and disposed inside the frame; and a distorted pattern The pair of inner wall surfaces fixed to the frame facing each other across the vibrating membrane, and the opposite end faces on the opposite side to the fixed surface have a plurality of permanent magnets different in magnetic properties. According to the present invention, since it is designed to have a plurality of permanent magnets which are fixed to the pair of inner wall surfaces of the frame in a phase-shifted configuration and which have mutually different magnetic faces on opposite sides of the fixed surface, The permanent magnets in the unmagnetized state are mounted to the frame, and after the electromagnetic converter is assembled, all the permanent magnets are magnetized. Therefore, the process of magnetic processing can be reduced, and the efficiency of assembly work can be improved. BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings. First Embodiment Fig. 1 is an external view showing a structure of an electromagnetic transducer 10 according to a first embodiment of the present invention. Fig. 1(a) is an external front view, and Fig. 1(b) is an external side view, Fig. 1 (c) is a plan view of the appearance, and Fig. 1 (d) is a rear view of the appearance. In the first drawings (a) and (b), the structure which is accommodated in the inner portion of the frame 15 and is not actually visible is shown by a broken line. Fig. 2 is a cross-sectional view showing the structure of the electromagnetic converter 10 according to the first embodiment of the present invention, and Fig. 2(a) is a cross-sectional view taken along the line AA shown in Fig. 1(a). 2(b) is a cross-sectional view taken along the line BB shown in Fig. 1(a), and Fig. 2(c) is taken along the line CC shown in Fig. 1(a). Sectional view. Fig. 3 is a perspective view showing the appearance of the diaphragm 11 of the electromagnetic transducer 10 of the first embodiment of the present invention. The first to third figures are diagrams which are exaggerated and enlarged for the sake of simplicity of explanation, and may differ from the actual ratio. The electromagnetic converter 10 is composed of an upper frame 16, a permanent magnet 12, a diaphragm 11, a permanent magnet 13, and a lower frame 17. The upper frame 16 and the lower frame 17 constitute a frame 15, which is a hollow frame structure inside. Although it is called the upper frame and the lower frame for convenience, it may be reversed. The inner wall surface of the upper frame 16, that is, the surface facing the vibrating membrane 11, φ is fixed to the permanent magnet 12 by an adhesive at a predetermined interval. The inner wall surface of the lower frame 17, that is, the position facing the diaphragm 11 and the gap between the permanent magnets 12, and the plurality of permanent magnets 13 are fixed by an adhesive. Therefore, as shown in the cross-sectional view of Fig. 2(a), an arrangement in which the permanent magnets 12, 13 are fixed to the positions where the upper frame 16 and the lower frame 17 are shifted from each other is formed. As shown in Fig. 2(a), the permanent magnet 12 fixed to the upper frame 16 is formed to have an N-pole end face fixed to the upper frame 16, and an end face facing the diaphragm 11 is formed as an S-pole. On the other hand, the permanent magnet 13 fixed to the lower frame 17 7 321031 201018264 is formed such that the end face fixed to the lower frame 17 is formed as an S pole, and the end face opposed to the diaphragm 11 is formed as an N pole. Therefore, the permanent magnets 12, 13 are configured to have mutually different polarities at opposite end faces on the side opposite to the face fixed to the frame. Further, the portions of the upper side frame 16 and the lower side frame 17 to which the permanent magnets 12, 13 are not fixed are provided with sound emitting holes 15a which are open to the outside at regular intervals. The diaphragm 11 is made of a sheet-like base material 11a of a thin polymer material. This base material 11a is three-dimensionally structured into a concavo-convex shape having a width corresponding to the fixed interval of the permanent magnets 12, 13. This uneven shape is a structure in which the concavities and convexities formed by the opposing end faces of the permanent magnets 12, 13 are formed. A conductor coil lib formed in a meandering shape is formed on the surface of the diaphragm 11. The conductor coil lib is formed by etching a foil of an electrical conductor of copper or aluminum or punching it with a press machine or the like. The diaphragm support member 14 is fixed to the outer peripheral surface of the vibrating membrane 11, and the vibrating membrane support member 14 is fixed to the inner periphery of the lower frame 17, whereby the vibrating membrane 11 is supported to be vertically displaceable. As shown in Fig. 2(a), when the diaphragm support member 14 fixes the diaphragm 11 to the lower frame 17, it is aligned so that the conductor coils lib are at the heights of the end faces of the permanent magnets 12, 13 facing each other. s position. Further, the uneven shape of the base material 11a is formed so as not to come into contact with the permanent magnets 12, 13 when the diaphragm 11 supported by the diaphragm support member 14 vibrates and is displaced up and down, and the diaphragm 11 and the permanent magnets 12, 13 There is a space between 8 321031 201018264. Further, the surface of the vibrating membrane 11 and the back surface of the diaphragm 11 are provided with a rib structure to increase the rigidity of the vibrating structure 11c. . Or the diaphragm of the concave 6 structure ❹ ❹ ' 针对 水 水 水 水 针对 针对 针对 针对 针对 针对 针对 针对 针对 针对 针对 针对 针对 针对 针对 针对 针对 针对 针对 针对 针对 针对 针对 针对 针对 针对 针对 针对 针对 针对 针对 针对 针对 针对 针对 针对 针对 针对 针对 针对 针对 针对 针对Samples! The lower frame 17' is then assembled with the vibrating membrane u clamped to the "long-term magnet 13". Then, for assembly = the electromagnetic converter 1 (in the upper frame 16 and the lower frame 17 converter 10, in the phase magnetic, the permanent magnets 12, 13 are simultaneously perpendicular to the direction of the permanent magnet 12, The relative direction of the magnetization of the opposite direction of the 13th. Therefore, the polarity of the ''the formation of mutually different skins for the electromagnetic converter 1〇 red is illustrated in the first and second figures. The current (audio signal) is supplied to the vibration impeding converter 10. When the conductor coil lib of the second and the eleventh is emitted from the N pole of the outer permanent magnet U, the s pole current from the rear to the permanent magnet 12 is connected to the conductor coil. The llb is orthogonal and the magnetic flux directions of 12 and 13 are substantially yoke. At this time, the current flowing in the pattern forming the permanent magnet ring pattern is electromagnetically coupled to the meandering density of the fish and the corner conductor coil 11b. The magnetic pattern of the long-lasting iron 12,13 (Peisheng. Under the driving force generated, according to the Fleming, there will be a driving force to produce the film 11 to vibrate. This vibration is supported by the diaphragm support material 14 The sound emission hole 15a of the excavation 15 emits audio reproduction sound According to the first embodiment described above, since the diaphragm 1 is formed into a concave-convex shape, the permanent magnets 12' 13 are arranged in a positionally misaligned configuration, and the permanent magnets 12 are arranged. Since the direction of the magnetic poles is the same as the direction of the magnetic poles of the permanent magnets 13, the permanent magnets 12 and 13 are magnetized after the assembly of the electromagnetic converter 10, so that it can be reduced as in the past gamuzon type speakers. When the permanent magnet is magnetized and attached to the pile frame while paying attention to the direction of the magnetic poles, the assembly work efficiency can be improved. Further, since the electromagnetic converter 10 is magnetized after assembly, the assembly operation is not performed. In the case where foreign matter such as iron powder is mixed in, it is possible to prevent the occurrence of abnormal noise in the electromagnetic converter 1 而, and it is possible to easily produce the high-quality electromagnetic converter 1 〇. The conductor coil 11b is formed on one side surface of the base material 11a, and may be formed on both the front and back surfaces of the base material 11a as shown in Fig. 2(a). Case, the audio can be more faithfully reproduced sound into an audio signal.
Q 另外上述的實施形態1 ’雖為在電磁轉換器1 〇的組 裝後再一併使固定於框架15的永久磁鐵12，13著磁之構 成，但亦可為將上側框架16及下側框架17分開而分別使 永久磁鐵12, 13著磁之構成。 另外，上述的實施形態1 ,雖為使永久磁鐵12，13排 成三列之構成，但只要是兩列以上的構成可得到與實施形 態1同樣的效果。 實施形態2 321031 10 201018264 第4圖係顯示本發明之實施形態2的電磁轉換器10的 構造之剖面圖，第4圖（a)係在相當於第1圖（a)所示的A-A 線之位置將該電磁轉換器10切斷所見之剖面圖，第4圖（b) 係在相當於第1圖（a)所示的B-B線之位置將該電磁轉換器 10切斷所見之剖面圖。第4圖中，對於與在上述實施形態 1中說明過的電磁轉換器10相同或相當的部份都標以相同 的符號且省略其說明。 第4圖所示的電磁轉換器10，係在永久磁鐵12，13 ® 其各自的與振動膜11相向之端面，接著固定有用來提高磁 通密度之鐵板18。 在電磁轉換器10中，因為鐵板18與導體線圈lib在 相同高度的位置，所以集中於鐵板18之磁通與流通於導體 線圈lib的電流做電磁性的耦合，而可得到更大的音壓準 位。 根據上述的實施形態2,形成：在永久磁鐵12，13其 @ 各自的與振動膜11相向之端面接著固定鐵板18之構成。 因此，可提高通過導體線圈lib之磁通密度。 (產業上之可利用性） 如以上所述，本發明之電磁轉換器，因為在組裝後才 進行著磁以防止異物混入而不會有異音產生，所以適合用 於揚聲器。 【圖式簡單說明】 第1圖係顯示本發明之實施形態1的電磁轉換器的構 造之外觀圖，第1圖（a)係外觀正面圖，第1圖（b)係外觀 11 321031 201018264 側面圖，第1圖（C)係外觀平面圖，第1圖（d)係外觀背面 圖。 第2圖係顯示本發明之實施形態1的電磁轉換器的構 造之剖面圖’第2圖（a)係沿著第1圖（a)所示的A-A線切 斷所見之剖面圖，第2圖（b)係沿著B-B線切斷所見之剖 面圖’第2圖（c)係係沿著C-C線切斷所見之剖面圖。 第3圖係顯示本發明之實施形態1的電磁轉換器的振 動膜的外觀之斜視圖。 第4圖係顯示本發明之實施形態2的電磁轉換器的構 ❹ 造之剖面圖’第4圖（a)係在相當於第1圖（a)所示的A-A 線之位置切斷所見之剖面圖，第4圖（b)係在相當於b-B線 之位置切斷所見之剖面圖。 【主要元件符號說明】 10 電磁轉換器 11 振動膜 11a 基材 lib 導體線圈 11c 振動膜補強構造部 12 永久磁鐵 13 永久磁鐵 14 振動膜支持材 15 框架 15a 放音孔 16 上侧框架 17 下侧框架 18 鐵板 321031 12Further, in the above-described first embodiment, the permanent magnets 12 and 13 fixed to the frame 15 are magnetized after the assembly of the electromagnetic transducer 1 ,, but the upper frame 16 and the lower frame may be used. 17 separates and causes the permanent magnets 12, 13 to be magnetically formed. Further, in the first embodiment described above, the permanent magnets 12 and 13 are arranged in three rows. However, as long as the configuration is two or more rows, the same effects as in the first embodiment can be obtained. Embodiment 2 321031 10 201018264 Fig. 4 is a cross-sectional view showing the structure of an electromagnetic converter 10 according to Embodiment 2 of the present invention, and Fig. 4(a) is a line corresponding to the AA line shown in Fig. 1(a). The electromagnetic converter 10 is cut at a position where it is seen, and Fig. 4(b) is a cross-sectional view showing the electromagnetic converter 10 at a position corresponding to the BB line shown in Fig. 1(a). In the fourth embodiment, the same or equivalent portions as those of the electromagnetic converter 10 described in the first embodiment are denoted by the same reference numerals, and their description will be omitted. The electromagnetic converter 10 shown in Fig. 4 is attached to the end faces of the permanent magnets 12, 13 ® facing the vibrating membrane 11, and then an iron plate 18 for increasing the magnetic flux density is fixed. In the electromagnetic converter 10, since the iron plate 18 and the conductor coil lib are at the same height position, the magnetic flux concentrated on the iron plate 18 and the current flowing through the conductor coil lib are electromagnetically coupled, and a larger one can be obtained. Sound pressure level. According to the second embodiment described above, the iron plates 18 are fixed to the end faces of the permanent magnets 12 and 13 which are opposed to the diaphragm 11 . Therefore, the magnetic flux density passing through the conductor coil lib can be increased. (Industrial Applicability) As described above, the electromagnetic converter of the present invention is suitable for use in a speaker because it is magnetized after assembly to prevent foreign matter from entering without abnormal noise. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is an external view showing a structure of an electromagnetic converter according to a first embodiment of the present invention. Fig. 1(a) is a front view of the appearance, and Fig. 1(b) is an appearance 11 321031 201018264. Fig. 1(C) is a plan view of the appearance, and Fig. 1(d) is a rear view of the appearance. Fig. 2 is a cross-sectional view showing the structure of the electromagnetic converter according to the first embodiment of the present invention. Fig. 2(a) is a cross-sectional view taken along the line AA shown in Fig. 1(a), and second. Fig. 2(b) is a cross-sectional view taken along line BB. Fig. 2(c) is a cross-sectional view taken along the line CC. Fig. 3 is a perspective view showing the appearance of a vibration film of the electromagnetic converter according to the first embodiment of the present invention. Fig. 4 is a cross-sectional view showing the configuration of the electromagnetic converter according to the second embodiment of the present invention. Fig. 4(a) shows the position cut at the position corresponding to the line AA shown in Fig. 1(a). In the cross-sectional view, Fig. 4(b) is a cross-sectional view taken at a position corresponding to the line bB. [Explanation of main components] 10 Electromagnetic converter 11 Vibrating membrane 11a Substrate lib Conductor coil 11c Vibrating membrane reinforcing structure 12 Permanent magnet 13 Permanent magnet 14 Vibrating membrane support material 15 Frame 15a Sound hole 16 Upper side frame 17 Lower side frame 18 iron plate 3210012 12