201034033 六、發明說明： 【發明所屬之技術領域】 本發明係有關用於低電壓差動訊號傳輸（LVDS)，且具 備電磁屏蔽功能之屏蔽扁平電纜。 【先前技術】 近年來，對於液晶顯示器之配線，係使用減少配線數 並以差動小振幅傳送的LVDS。LVDS中，特性阻抗係設定 ' 爲100 Ω程度。 φ 日本專利公開公報特開2006 - 32003號中，係揭示一 種扁平電纜來作爲適用於LVDS之電子機器內的配線。日 本新型登錄第3096395號係揭示一種對於扁平電纜之各信 號線爲特性阻抗一定，且於多數之信號線設置共通的接地 部。 曰本專利公開公報特開2005 — 93 1 7 8號係揭示一種屏 蔽扁平電纜。該屏蔽扁平電纜中，多數的平角導體係以絕 緣層而挾住其上下，進而以具有金屬層之屏蔽被覆帶加以 ® 覆蓋。金屬層係經由設置於絕緣層的開口而電性導通於預 •泰， 定的接地用之平角導體。 • 第5(A)圖係顯示習知之屏蔽扁平電纜1中之終端部2 的立體圖。屏蔽扁平電纜1中，複數條之扁平形導體3係 以絕緣樹脂膜4(上側膜4a、下側膜4b)而由上下加以挾住 並予以絕緣被覆》於屏蔽扁平電纜1之端部，除去上側膜 4a而露出作爲扁平形導體3之端子的部分，形成電纜終端 部2。又，於電纜終端部2未除去之下側膜4b係貼附有補 強帶6，成爲可插入連接於電性連接器之形態。 201034033 於上側膜4a，接地連接用之接地帶5係貼附在與扁平 形導體3不會產生電性短路之位置。接地帶5係以日本新 型登錄第3096395號、或日本專利公開公報特開2005 -93 178號所揭示之方法而電性導通於作爲接地用之扁平形 導體之任一者（省略圖示）。譬如由絕緣層、金屬層、導電 接著層的三層形狀所組成的薄膜，即屏蔽膜7，係其中一 部分重疊地捲繞於屏蔽扁平電纜1之外方面，且由外部屏 ' 蔽平型導體3。屏蔽膜7係電性連接於接地帶5。屏蔽扁平 Q 電纜1之特性阻抗係藉由改變絕緣樹脂膜4之比介電率及 厚度等而爲預定値（譬如100Ω程度）。 於屏蔽扁平電纜1之終端部2，爲插入連接於電性連 接器，係讓扁平形導體3露出。因此，由接地帶5起，特 性阻抗係有所變化。第5(B)圖係說明終端部2中之特性阻 抗的槪念圖》於電纜終端部2，阻抗降低。此種阻抗的變 化若存在信號傳送路徑中，恐將產生傳送信號的反射而有 傳送損失。 〇 日本專利公開公報特開2006 — 32003號中，係記載有 一種令扁平電纜之特性阻抗爲預定値之1〇〇 Ω。惟，其終端 ' 部的構成並未明白揭示，且未清楚詳細交代迄至電纜終端 部附近之阻抗。又，其雖揭示附加電磁波干擾（EMI)防止金 屬耦合，但由於無屏蔽層’因此並未明白揭示其與特性阻 抗之關係、抑或如何防止EMI。 【發明内容】 [發明欲解決之課題] 本發明之目的係提供一種可跨電纜全長提供屏蔽’且 201034033 於電纜終端部之阻抗變化少的屏蔽扁平電纜。 [用以解決課題之手段] 本發明之屏蔽扁平電纜係包含有：複數條扁平形導 體，係以預定間隔配列；第1絕緣樹脂膜及第2絕緣樹脂 膜，係由該複數條扁平形導體之配列面之上下挾住前述複 數條扁平形導體而予以絕緣被覆；及屏蔽膜，係被覆前述 第1絕緣樹脂膜及第2絕緣樹脂膜。且該屏蔽扁平電纜係 ' 至少於其中一端部，除去前述第1絕緣樹脂膜之前端部而 φ 讓複數條扁平形導體露出於第1絕緣樹脂膜側，且第2絕 緣樹脂膜之前端與複數條扁平形導體之前端一致。屏蔽扁 平電纜於端部係包含有：補強帶，係貼附於第2絕緣樹脂 膜之外方面；第1接地帶，係貼附於第1絕緣樹脂膜上， 其一端與第1絕緣樹脂膜之端部相距預定距離，另一端與 屏蔽膜重疊而電性連接；及第2接地帶，係貼附於補強帶 ，上，且其中一部分與屏蔽膜重疊而電性連接。 本發明之一個態樣中，第1接地帶與第2接地帶係一 ® 體地形成，於彎折部反折且貼附於雙面。其他態樣中，屏 蔽膜係貼附成包覆電纜長向方向之兩側緣。另一態樣中， ' 屏蔽膜與絕緣樹脂膜之間，係配置有比介電率爲2.2〜3.2 之介電體膜，且阻抗調整爲預定値。 【發明之功效】 依本發明，係可降低於屏蔽扁平電纜之終端部的特性 阻抗變化，實現良好的信號傳送。 【實施方式】 以下，參照圖式說明本發明之實施形態。圖式係以說 201034033 明爲目的，非欲以限定發明之範圍者。於圖式中，爲避免 說明重複，相同的元件標號係顯示同一部分。圖面中之尺 寸比例不一定正確》 第1(A)圖係顯示本發明實施形態之屏蔽扁平電纜11 中之終端部的立體圖。屏蔽扁平電纜11中，複數條扁平形 導體1 3係以絕緣樹脂膜1 4之上側膜1 4 a (第1絕緣樹脂膜） 與下側膜14b(第2絕緣樹脂膜）由上下加以挾住而呈絕緣 ' 被覆。且至少於其中一端部將上側膜14a加以除去而露出 φ 成爲扁平形導體13之連接端子的部分，形成電纜終端部 12»又，在電纜終端部12,於未除去之下側膜14b係貼附 有補強帶16而補強強度，成爲可插入連接於電性連接器 (未圖示）之形狀。補強帶16之端部係與下側絕緣樹脂膜 14b之端部一致，補強整個端部在強度面上是較佳的。 於上側膜14a係貼附有接地連接用之接地帶15a(第1 接地帶）。接地帶15a於上側膜14a之前端附近，係與露出 之扁平形導體13爲不產生電性短路之程度（譬如3ram〜4rom) ® 而分離。又，如後述，接地帶15a係與扁平形導體13之任 一者電性導通且接地連接。 ' 補強帶16之下方面亦貼附有與接地帶15a相同的接地 帶15b(第2接地帶）。接地帶15a與接地帶15b係挾住扁 平形導體13而相對向。接地帶15b係其前端較接地帶15a 之前端以距離T所示般地位在端部側，且屏蔽扁平電纜11 插入連接於電性連接器時，係貼附成與連接器接觸子間不 會產生電性短路。藉由設置接地帶15b，連接器與接地帶 間可避免電容產生大幅變化，可抑制特性阻抗較大的變化。 201034033 屏蔽膜17a、17b係與接地帶15a、15b之一部分重疊， 且大致跨電纜全長而由上下挾住電纜並加以貼附，讓兩側 緣之耳部20相互接著而閉合。屏蔽膜17a、17b係經由接 地帶15a、15b而接地連接，對於電纜發揮屏蔽功用。又， 屏蔽膜17a、17b與作爲信號線動作的複數條扁平形導體 13之間，於除終端附近外之區域形成均等的電容（電容器 容量），實現均等的阻抗。 ' 特性阻抗係依分佈於作爲信號線之扁平形導體13與 ❹ 屏蔽膜17a、17b間的電容器容量而加以決定。該電容器容 量係可藉由改變絕緣樹脂膜14之比介電率與薄膜厚度而 加以設定。僅有絕緣樹脂膜14而不易獲得預定的特性阻抗 (譬如LVDS用的100Ω)時，係藉由於絕緣樹脂膜14與屏 蔽膜17a、17b之間配置低介電率之低介電體膜18a、18b 而成爲預定的特性阻抗。 第1(B)圖係屏蔽扁平電纜11之a— a剖面圖》扁平形 導體13係譬如由銅箔、錫焊軟銅箔等的導電性金屬箔組 Φ 成。考慮到信號傳送的電流値與電纜的滑動性，扁平形導 體13之尺寸與配置係厚度12/ζιη〜50从m、寬度0.2mm〜 0.3mm 程度、0.3mm〜0.5mm 間隔。 上側膜14a、下側膜14b各自係由絕緣層28與接著劑 層22之二層所組成》絕緣層28係使用柔軟性優異之樹脂 材料，譬如聚酯樹脂、聚苯硫醚樹脂、聚醯亞胺樹脂等的 具通用性之樹脂膜，其厚度爲〜50//ra。作爲聚酯樹 脂，可舉出聚對苯二甲酸乙二酯樹脂、聚萘二甲酸乙二酯 樹脂、聚萘二甲酸丁二酯樹脂等的樹脂材料。又，該等樹 201034033 脂膜中，由電性特性、機械特性、成本等的觀點，宜使用 聚萘二甲酸乙二酯樹脂。再者，藉由使用由聚醯亞胺及聚 苯硫醚組成的樹脂膜，係可具有滿足美國保險業者安全試 驗所發行的安全認證（UL規格）之耐熱性。 接著劑層22係使用由樹脂材料形成者，可舉出譬如於 聚酯系樹脂及聚烯烴系樹脂添加阻燃劑之接著劑等。該接 著劑層係以厚度20/zra〜50ym形成。上側膜14a與下側膜 ' 14b係挾住扁平形導體13而朝向接著劑層22,且邊以加熱 〇 滾輪加熱邊接合而加以貼合並一體化。 第1及第2接地帶15a、15b係由導電層23及接著劑 層24組成。導電層23係使用譬如厚度爲18/zm〜35νιη程 度的錫焊銅箔，考慮到彎折耐性，宜使用軋延銅箔。接著 劑層24係譬如以丙烯系之接著層、樹脂基材、接著層之順 序加以積層，且使用加上導電層23,整體的厚度係配合連 接器的尺寸，爲85#ra〜125#m程度者。接地帶15a、15b 係將帶狀者切爲預定的長度而貼附於上側膜、下側膜。 © 屏蔽膜17a、17b係使用譬如樹脂層25、屏蔽層26及 導電接著層27之三層構造者。樹脂層25係薄膜基材，防 ' 止屏蔽層26之剝離及腐蝕以維持電纜之可靠度。樹脂層 25係使用聚對苯二甲酸乙二酯之厚度爲9/zm程度的樹脂 膜。屏蔽層2 6係譬如於樹脂層25之樹脂膜的背面蒸鍍銀 等的導電性金屬而形成。 導電接著層27除貼附於絕緣樹脂膜14，並可獲得與 接地帶15a、15b之電性導通而產生屏蔽之功能，譬如於屏 蔽層26之銀蒸鍍面塗佈銀糊而加以形成。屏蔽膜17a、17b .201034033 係整體的厚度在30 Mm程度，分爲上下而直接或經低介電 體膜18a、18b而貼附於絕緣樹脂膜14之外周》 接地帶15a，15b之導傳層23係其中一部分與屏蔽膜 17之導電接著層27呈電性接觸。並且絕緣樹脂膜14a、14b 中，平型導體13之任一成爲接地線者的上部或下部的部 分，係於長向方向加以除去至少一部分，且接地線與屏蔽 膜17之導電接著層27呈電性接觸。具低介電體膜18a、 ' 18b時，低介電體膜18a、18b之一部分亦加以除去，且接 φ 地線與導電接著層27呈電性接觸。如此，接地帶15a、15b、 屏蔽膜17及接地線係電性導通。藉由讓接地線接地，接地 帶及屏蔽膜亦接地。 低介電體膜18a、18b係在僅有絕緣樹脂膜14而無法 得到預定的特性阻抗之場合加以使用。作爲低介電體膜 18a、18b，係使用具有低介電性，且以柔軟性、加工性優 異之樹脂材料爲主成分者。譬如作爲具有低介電性及柔軟 性者，係可舉出聚烯烴系之樹脂、聚丙烯（PP)、聚乙烯樹 © 脂（PE)、酸變性聚乙烯樹脂、乙烯醋酸乙烯酯共聚物 (EVA)、乙烯丙烯酸乙酯等。又，作爲低介電性與加工性優 ' 異者，可舉出低密度聚乙烯樹脂（LDPE)、直鏈狀低密度聚 乙烯樹脂（LLDPE)。 低介電體膜18a、18b係將譬如比介電率2.2〜3.2、 厚度100/zm〜3 50 /zm程度者重叠於絕緣樹脂膜14而加以 使用。藉此，可將屏蔽扁平電纜之特性阻抗在50Ω〜110 Ω之範圍設定爲任意値。 第2(A)圖係顯示本發明其他實施形態之屏蔽扁平電纜 •10- 201034033 21中之終端部的立體圖。屏蔽扁平電纜21係以 地帶15(第2(B)圖）而形成屏蔽扁平電纜11中之 帶15a與第2接地帶15b。接地帶15係經由彎折 一體地形成第1接地帶部15d及第2接地帶部1 於接地帶15，第2接地帶部15e側係較第1接地 在寬度上大出第1圖之距離T許多》 接地帶1 5係以第1接地帶部1 5 d而貼附於扁 ' 1 3露出之側的上側膜1 4 a，其次，以彎折部1 5 c 〇 曲，並以第2接地帶部15e而貼附於下側的補強草 方面。接地帶15中，無須讓第1接地帶部15d與 帶部15e分別各自與設定爲接地連接用之扁平形 通。又，因第1接地帶部15d與第2接地帶部1: 爲一片接地帶15加以管理，故零件數少而易於管 第3(A)圖係顯示本發明其他實施形態之屏蔽 31中之終端部的立體圖。屏蔽扁平電纜31係以 蔽膜17而一體地形成屏蔽扁平電纜11中之上側 Φ 17a與下側的屏蔽膜17b之例（第3(B)圖）。屏蔽H 含有於中央部貼附在下側（補強帶側）之屏蔽膜1 ' 其兩側部具有經彎折部1 7 c而貼附於上側之屏蔽 屏蔽膜1 7e係貼附於低介電體膜，以與貼附 側之第2屏蔽膜15b有部分地重疊。兩側之屏蔽 部分，係以彎曲部1 7 c而彎折成包繞電纜側緣， 低介電體膜。且兩側的屏蔽膜17d係於電纜的上 央部分，沿長向方向相互貼附以具有重疊而加以 屏蔽膜17不會產生於使用上下兩片屏蔽膜1 一片的接 第1接地 部15c而 5 e。又， 帶部1 5d 平形導體 而加以彎 学1 6之外 第2接地 導體爲導 5 e係可作 ;理。 扁平電纜 一片的屏 的屏蔽膜 I 1 7係包 7 e，且於 膜 17d ° 於補強帶 膜17d的 並貼附於 方面之中 閉合。 7a，1 7b 時 -11- 201034033 所產生的耳部20。其結果，可避免由於露出於耳部20之 屏蔽層的導電體而於配線機器內引起電性短路之問題。 又’讓屏蔽膜17之前端17f配合接地帶的形狀而進行加工 外’亦可不對於帶狀的薄膜施予特別的加工而直接加以使 用’因可以一片的屏蔽膜進行管理，因此零件數量少而易 於管理》 第4(A)圖、第4(B)圖係顯示本發明其他實施形態之屏 " 蔽扁平電纜41A、41B中之終端部的立體圖。電纜41A係於 〇 屏蔽扁平電纜11中，讓低介電體膜設置於電纜終端部時之 例，電纜41B係於屏蔽扁平電纜31中，讓低介電體膜設置 於電纜終端部時之例。屏蔽扁平電纜41A中，上側的接地 帶15a係貼附於低介電體膜18a之上方面。於下側，補強 帶16係作爲絕緣體作用。因此，亦可不將低介電體膜18b 積層於補強帶16之外方面。於屏蔽扁平電纜41B，除屏蔽 膜17的形狀不同，其他皆與電纜41A相同。 任一之例中，與絕緣樹脂膜14積層之低介電體膜 O 18a、18b係改變形成於信號線之扁平形導體13與接地之 屏蔽膜17a、17b間的電容器容量（電容）而實現預定的特性 ' 阻抗。低介電體膜1 8 a、1 8b係令其介電率縮小而增加特性 阻抗，又，可藉由增加其厚度而增加特性阻抗。因此，以 屏蔽扁平電纜而減輕於電纜終端部12之特性阻抗的變化 時，宜至電纜終端部都盡可能地存有均等的絕緣體（介電 體）。 如前述，在不妨礙的範圍藉由設置低介電體膜18a、 18b至電纜終端部12，係可跨電纜全長而做成均等地分佈 -12- 201034033 之電容器容量。且，如前述，可藉由於補強帶側亦設置於 電纜終端部之接地帶，而做成具有穩定之特性阻抗的屏蔽 扁平電纜。 [產業上之可利用性] 本發明之屏蔽扁平電纜作爲LVDS用之配線材料係極 爲有用。 【圖式簡單說明】 第1(A)圖係顯示本發明實施形態之屏蔽扁平電纜中之 Ο 終端部的立體圖，第1(B)圖係顯示第1(A)圖中之a— a剖面 圖。 第2(A)圖係顯示本發明其他實施形態之屏蔽扁平電纜 中之終端部的立體圖，第2(B)圖係顯示該實施形態中之接 地帶的立體圖。 第3(A)圖係顯示本發明另一實施形態之屏蔽扁平電纜 中之終端部的立體圖，第3(B)圖係顯示該實施形態中之屏 蔽膜的立體圖。 ® 第4(A)圖、第4(B)圖係顯示本發明其他實施形態之屏 蔽扁平電纜中之終端部的立體圖。 第5(A)圖係顯示習知之屏蔽扁平電纜中之終端部的立 體圖，第5(B)圖係說明終端部中之特性阻抗的槪念圖。 【主要元件符號說明】 1 屏蔽扁平電纜 2 終端部 3 扁平形導體 -13- 201034033201034033 VI. Description of the Invention: [Technical Field of the Invention] The present invention relates to a shielded flat cable for low voltage differential signal transmission (LVDS) and having an electromagnetic shielding function. [Prior Art] In recent years, for the wiring of a liquid crystal display, LVDS which reduces the number of wirings and transmits with a small differential amplitude is used. In LVDS, the characteristic impedance is set to '100 Ω. In Japanese Patent Laid-Open Publication No. Hei. No. 2006-32003, a flat cable is disclosed as a wiring in an electronic machine suitable for LVDS. Japanese Laid-Open No. 3096395 discloses a grounding portion in which a signal impedance is constant for each signal line of a flat cable and a common signal line is provided for a plurality of signal lines. A flat panel cable is disclosed in Japanese Laid-Open Patent Publication No. 2005-937-18. In the shielded flat cable, most of the flat-angle guide systems are held up and down with an insulating layer, and are covered with a shielded tape having a metal layer. The metal layer is electrically connected to the pre-determined grounding conductor for the grounding via an opening provided in the insulating layer. • Fig. 5(A) is a perspective view showing the terminal portion 2 in the conventional shielded flat cable 1. In the shielded flat cable 1, a plurality of the flat conductors 3 are covered by the insulating resin film 4 (the upper film 4a and the lower film 4b) and are insulated and covered by the upper and lower portions of the shielded flat cable 1 to be removed. The upper film 4a exposes a portion which is a terminal of the flat conductor 3, and the cable end portion 2 is formed. Further, the reinforcing tape 6 is attached to the lower side film 4b without removing the cable end portion 2, and is inserted into the electrical connector. 201034033 In the upper film 4a, the grounding strap 5 for grounding is attached to a position where the flat conductor 3 does not electrically short. The grounding belt 5 is electrically connected to any of the flat conductors for grounding (not shown) by the method disclosed in Japanese Laid-Open Patent Publication No. 3096395 or Japanese Laid-Open Patent Publication No. 2005-93178. For example, a film composed of a three-layer shape of an insulating layer, a metal layer, and a conductive adhesive layer, that is, a shielding film 7 is partially overlapped and wound around the shielded flat cable 1 and is shielded by an external screen. 3. The shielding film 7 is electrically connected to the ground strap 5. The characteristic impedance of the shielded flat Q cable 1 is predetermined (e.g., about 100 Ω) by changing the specific dielectric constant and thickness of the insulating resin film 4. The terminal portion 2 of the shielded flat cable 1 is inserted into and connected to the electrical connector to expose the flat conductor 3. Therefore, the characteristic impedance changes from the grounding strip 5. The fifth (B) diagram illustrates the concept of the characteristic impedance in the terminal unit 2, and the impedance is lowered at the cable end portion 2. If such a change in impedance exists in the signal transmission path, there is a fear that a reflection of the transmission signal will occur and there is a transmission loss. In Japanese Laid-Open Patent Publication No. 2006-32003, there is described a characteristic that the characteristic impedance of the flat cable is 1 〇〇 Ω. However, the configuration of the terminal portion is not disclosed, and the impedance to the vicinity of the cable terminal portion is not clearly explained in detail. Further, although it discloses that additional electromagnetic interference (EMI) prevents metal coupling, it does not understand the relationship with the characteristic impedance or how to prevent EMI because of the absence of the shielding layer. SUMMARY OF THE INVENTION [Problem to be Solved by the Invention] An object of the present invention is to provide a shielded flat cable which can provide a shield across the entire length of the cable and which has a small change in impedance at the cable end portion of 201034033. [Means for Solving the Problem] The shielded flat cable of the present invention includes: a plurality of flat conductors arranged at predetermined intervals; and the first insulating resin film and the second insulating resin film are the plurality of flat conductors The plurality of flat conductors are placed under the surface of the array to be insulated and covered, and the shielding film covers the first insulating resin film and the second insulating resin film. In addition, the shielded flat cable is at least one end portion, and the end portion of the first insulating resin film is removed, φ is made to expose a plurality of flat conductors on the side of the first insulating resin film, and the front end of the second insulating resin film is plural. The flat ends of the flat conductors are identical. The shielded flat cable includes a reinforcing tape attached to the second insulating resin film at the end portion, and the first grounding tape is attached to the first insulating resin film, and one end thereof and the first insulating resin film The ends are spaced apart from each other by a predetermined distance, and the other end is electrically connected to the shielding film; and the second grounding tape is attached to the reinforcing tape, and a part thereof is electrically connected to the shielding film. In one aspect of the present invention, the first ground strap and the second ground strap are formed integrally, and are folded back at the bent portion and attached to both sides. In other aspects, the shielding film is attached to both sides of the cable in the longitudinal direction. In another aspect, a dielectric film having a specific dielectric constant of 2.2 to 3.2 is disposed between the shielding film and the insulating resin film, and the impedance is adjusted to a predetermined value. [Effect of the Invention] According to the present invention, it is possible to reduce the characteristic impedance change at the end portion of the shielded flat cable and achieve good signal transmission. [Embodiment] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The schema is intended to be in the meaning of the scope of the invention. In the drawings, the same reference numerals are used to the The size ratio in the drawing is not necessarily correct. Fig. 1(A) is a perspective view showing the end portion of the shielded flat cable 11 according to the embodiment of the present invention. In the shielded flat cable 11, a plurality of flat conductors 13 are sandwiched between the upper film 14 a (first insulating resin film) and the lower film 14 b (second insulating resin film) of the insulating resin film 14 It is insulated 'coated. At least one end portion of the upper film 14a is removed to expose a portion where φ becomes a connection terminal of the flat conductor 13, and the cable end portion 12» is formed. Further, at the cable end portion 12, the side film 14b is attached without being removed. The reinforcing tape 16 is attached to reinforce the strength, and is formed into a shape that can be inserted and connected to an electrical connector (not shown). The end portion of the reinforcing tape 16 is aligned with the end portion of the lower insulating resin film 14b, and it is preferable to reinforce the entire end portion on the strength surface. A ground strap 15a (first ground strap) for ground connection is attached to the upper film 14a. The ground strap 15a is separated from the exposed flat conductor 13 to the extent that it does not cause an electrical short (e.g., 3 ram to 4 rom) ® in the vicinity of the front end of the upper film 14a. Further, as will be described later, the ground strap 15a is electrically connected to any of the flat conductors 13 and is grounded. The grounding strap 15b (second grounding strap) identical to the grounding strap 15a is attached to the lower side of the reinforcing strap 16. The ground strap 15a and the ground strap 15b are opposed to each other by the flat conductor 13. The grounding strap 15b has a front end that is positioned on the end side as the distance T from the front end of the grounding strap 15a, and when the shielded flat cable 11 is inserted and connected to the electrical connector, the attachment is not in contact with the connector. An electrical short circuit is generated. By providing the ground strap 15b, a large change in capacitance can be avoided between the connector and the ground strap, and a large change in characteristic impedance can be suppressed. 201034033 The shielding films 17a, 17b are partially overlapped with one of the grounding straps 15a, 15b, and are clamped up and down across the entire length of the cable, and the ears 20 of the both sides are closed to each other. The shielding films 17a and 17b are grounded via the contact regions 15a and 15b, and function as a shield for the cable. Further, between the shielding films 17a and 17b and the plurality of flat conductors 13 operating as signal lines, uniform capacitance (capacitor capacity) is formed in a region other than the vicinity of the terminal, and an equal impedance is realized. The characteristic impedance is determined by the capacity of the capacitor distributed between the flat conductor 13 as the signal line and the 屏蔽 shielding films 17a and 17b. The capacity of the capacitor can be set by changing the specific dielectric ratio of the insulating resin film 14 and the film thickness. When the insulating resin film 14 is not easily obtained with a predetermined characteristic impedance (for example, 100 Ω for LVDS), a low dielectric film 18a having a low dielectric constant is disposed between the insulating resin film 14 and the shielding films 17a and 17b. 18b becomes a predetermined characteristic impedance. Fig. 1(B) is a cross-sectional view of the shielded flat cable 11 a-a. The flat conductor 13 is made of, for example, a conductive metal foil group Φ such as copper foil or soldered soft copper foil. Considering the current 値 of the signal transmission and the slidability of the cable, the size of the flat conductor 13 and the thickness of the arrangement 12/ζιη~50 are spaced from m, width 0.2 mm to 0.3 mm, and 0.3 mm to 0.5 mm. The upper film 14a and the lower film 14b are each composed of two layers of the insulating layer 28 and the adhesive layer 22. The insulating layer 28 is made of a resin material excellent in flexibility, such as a polyester resin, a polyphenylene sulfide resin, or a polyfluorene. A versatile resin film such as an imide resin has a thickness of 〜50//ra. The polyester resin may, for example, be a resin material such as polyethylene terephthalate resin, polyethylene naphthalate resin or polybutylene naphthalate resin. Further, in the 201034033 lipid film, a polyethylene naphthalate resin is preferably used from the viewpoints of electrical properties, mechanical properties, cost, and the like. Further, by using a resin film composed of polyimine and polyphenylene sulfide, it is possible to have heat resistance satisfying the safety certification (UL specification) issued by the American Insurance Company Safety Test. The subsequent layer 22 is formed of a resin material, and examples thereof include an adhesive for adding a flame retardant to a polyester resin or a polyolefin resin. The adhesive layer is formed to have a thickness of 20/zra to 50 μm. The upper film 14a and the lower film '14b are sandwiched between the flat conductors 13 and directed toward the adhesive layer 22, and joined while being heated by a heated crucible roller. The first and second ground straps 15a and 15b are composed of a conductive layer 23 and an adhesive layer 24. The conductive layer 23 is a soldered copper foil having a thickness of, for example, 18/zm to 35νηη, and in view of bending resistance, a rolled copper foil is preferably used. The adhesive layer 24 is laminated in the order of a acryl-based adhesive layer, a resin substrate, and a subsequent layer, and a conductive layer 23 is used, and the overall thickness is matched with the size of the connector, and is 85#ra~125#m. Degree. The grounding belts 15a and 15b are cut into a predetermined length and attached to the upper film and the lower film. © The shielding films 17a and 17b are three-layer structures using, for example, a resin layer 25, a shield layer 26, and a conductive adhesive layer 27. The resin layer 25 is a film substrate which prevents peeling and corrosion of the shield layer 26 to maintain the reliability of the cable. The resin layer 25 is a resin film having a thickness of polyethylene terephthalate of about 9/zm. The shield layer 26 is formed by depositing a conductive metal such as silver on the back surface of the resin film of the resin layer 25. The conductive adhesive layer 27 is attached to the insulating resin film 14 and can be electrically connected to the ground straps 15a and 15b to form a shield. For example, the silver vapor-deposited surface of the shield layer 26 is coated with a silver paste. The shielding films 17a, 17b. 201034033 are integrally formed to have a thickness of about 30 Mm, which is divided into the upper and lower sides or directly attached to the outer periphery of the insulating resin film 14 via the low dielectric films 18a and 18b. Layer 23 is partially in electrical contact with conductive backing layer 27 of shielding film 17. Further, of the insulating resin films 14a and 14b, any one of the flat conductors 13 that is the upper or lower portion of the grounding wire is removed in the longitudinal direction by at least a portion, and the grounding wire and the conductive adhesive layer 27 of the shielding film 17 are Electrical contact. When the low dielectric films 18a, 18b are provided, a portion of the low dielectric films 18a, 18b is also removed, and the ground wire is electrically contacted with the conductive via 27. Thus, the ground straps 15a, 15b, the shielding film 17, and the grounding wire are electrically connected. By grounding the ground wire, the ground strap and the shielding film are also grounded. The low dielectric films 18a and 18b are used in the case where only the insulating resin film 14 is provided and a predetermined characteristic impedance cannot be obtained. As the low dielectric films 18a and 18b, a resin material having low dielectric properties and excellent in flexibility and workability is used as a main component. For example, as a resin having low dielectric properties and flexibility, a polyolefin resin, polypropylene (PP), polyethylene resin (PE), acid-denatured polyethylene resin, or ethylene vinyl acetate copolymer ( EVA), ethylene ethyl acrylate, and the like. Further, examples of low dielectric properties and workability include low density polyethylene resin (LDPE) and linear low density polyethylene resin (LLDPE). The low dielectric films 18a and 18b are used by superposing, for example, a dielectric constant of 2.2 to 3.2 and a thickness of 100/zm to 3 50 /zm on the insulating resin film 14. Thereby, the characteristic impedance of the shielded flat cable can be set to any range from 50 Ω to 110 Ω. Fig. 2(A) is a perspective view showing a terminal portion of a shielded flat cable according to another embodiment of the present invention, 10 - 201034033. The shielded flat cable 21 is formed by the belt 15 (Fig. 2(B)) to form the belt 15a and the second ground belt 15b in the shielded flat cable 11. The ground strap 15 integrally forms the first ground strap portion 15d and the second ground strap portion 1 on the ground strap 15 via the bending, and the second ground strap portion 15e side is wider than the first ground in the width of the first map. A plurality of ground straps 1 5 are attached to the upper film 1 4 a on the side where the flat ' 1 3 is exposed by the first ground strap portion 15 5 d, and secondly, the bent portion 15 c is twisted, and 2 The grounding belt portion 15e is attached to the reinforcing grass on the lower side. In the grounding belt 15, it is not necessary to make the first grounding belt portion 15d and the belt portion 15e each have a flat shape for connection to the ground. Further, since the first ground strap portion 15d and the second ground strap portion 1 are managed by one ground strap 15, the number of components is small, and the third (A) diagram is shown in the shield 31 of another embodiment of the present invention. A perspective view of the terminal portion. The shielded flat cable 31 integrally forms an example of shielding the upper side Φ 17a of the flat cable 11 and the lower side shielding film 17b with the shielding film 17 (Fig. 3(B)). Shielding H includes a shielding film 1' attached to the lower side (reinforcing tape side) at the center, and a shielding film 1 7e attached to the upper side via the bent portion 1 7 c on both sides is attached to the low dielectric The body film partially overlaps the second shielding film 15b on the attachment side. The shield portions on both sides are bent to form a side wall of the cable, a low dielectric film, with a bent portion 1 7 c. The shielding films 17d on both sides are attached to the upper central portion of the cable, and are attached to each other in the longitudinal direction so as to overlap with each other. The shielding film 17 is not generated by the first grounding portion 15c using the upper and lower shielding films 1 . 5 e. Further, the belt portion 1 5d is a flat conductor and is bent to be 1 6. The second ground conductor is a guide. Flat cable The shielding film of the screen of one piece I 7 7 is 7 e, and is closed in the aspect where the film 17d is attached to the reinforcing film 17d and attached. Ears 20 produced by 7a, 1 7b -11- 201034033. As a result, the problem of causing an electrical short circuit in the wiring machine due to the conductor exposed to the shield layer of the ear portion 20 can be avoided. In addition, 'the front end 17f of the shielding film 17 can be processed in accordance with the shape of the grounding strip.' It can also be used without special processing for the strip-shaped film. 'The shielding film can be managed by one piece, so the number of parts is small. It is easy to manage. Fig. 4(A) and Fig. 4(B) are perspective views showing the end portions of the flat panel cables 41A and 41B according to the other embodiment of the present invention. The cable 41A is attached to the 〇 shielded flat cable 11, and the low dielectric film is placed in the cable end portion, and the cable 41B is placed in the shielded flat cable 31, and the low dielectric film is placed at the cable end portion. . In the shielded flat cable 41A, the upper ground strap 15a is attached to the low dielectric film 18a. On the lower side, the reinforcing tape 16 acts as an insulator. Therefore, the low dielectric film 18b may not be laminated on the reinforcing tape 16. The shielded flat cable 41B is the same as the cable 41A except that the shape of the shield film 17 is different. In either case, the low dielectric film O 18a, 18b laminated with the insulating resin film 14 changes the capacity (capacitance) of the capacitor formed between the flat conductor 13 of the signal line and the shielding films 17a and 17b of the ground. The predetermined characteristic 'impedance. The low dielectric film 18 8 a, 18 b reduces the dielectric constant and increases the characteristic impedance. Further, the characteristic impedance can be increased by increasing the thickness thereof. Therefore, when the flat cable is shielded and the characteristic impedance of the cable end portion 12 is reduced, it is preferable to have an equal insulator (dielectric) as far as possible at the cable end portion. As described above, by providing the low dielectric films 18a and 18b to the cable end portion 12 in a range that does not interfere, the capacitor capacity of -12-201034033 can be equally distributed across the entire length of the cable. Further, as described above, the shielded flat cable having a stable characteristic impedance can be formed by the ground strap provided on the reinforcing tape side also at the cable end portion. [Industrial Applicability] The shielded flat cable of the present invention is extremely useful as a wiring material for LVDS. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1(A) is a perspective view showing a terminal portion of a shielded flat cable according to an embodiment of the present invention, and Fig. 1(B) is a cross-sectional view showing a-a of Fig. 1(A). Figure. Fig. 2(A) is a perspective view showing a terminal portion of a shielded flat cable according to another embodiment of the present invention, and Fig. 2(B) is a perspective view showing a contact zone in the embodiment. Fig. 3(A) is a perspective view showing a terminal portion of a shielded flat cable according to another embodiment of the present invention, and Fig. 3(B) is a perspective view showing a shield film in the embodiment. Fig. 4(A) and Fig. 4(B) are perspective views showing the end portion of the shielded flat cable according to another embodiment of the present invention. Fig. 5(A) is a perspective view showing a terminal portion in a conventional shielded flat cable, and Fig. 5(B) is a view showing a characteristic impedance in a terminal portion. [Main component symbol description] 1 Shielded flat cable 2 Terminal section 3 Flat conductor -13- 201034033
4 絕緣樹脂膜 4 a 上側膜 4b 下側膜 5 接地帶 6 補強帶 7 屏蔽膜 11 屏蔽扁平電纜 12 電纜終端部 13 扁平形導體 4 絕緣樹脂膜 14a 上側膜（第1絕緣樹脂膜） 14b 下側膜（第2絕緣樹脂膜） 15 接地帶 15a 接地帶（第1接地帶） 15b 接地帶（第2接地帶） 15c 彎折部 15d 第1接地帶部 15e 第2接地帶部 16 補強帶 17 屏蔽膜 17a 屏蔽膜 17b 屏蔽膜 17c 彎折部 17d 、 17e 屏蔽膜 17f 前端 -14- 201034033 18a、 18b 低 介 電 體 膜 20 耳 部 21 屏 蔽 扁 平 電 纜 22 接 著 劑 層 23 導 電 層 24 接 著 劑 層 25 樹 脂 層 26 屏 蔽 層 27 導 電 接 著 層 28 絕 緣 層 3 1 屏 蔽 扁 平 電 纜 41A、41B 屏 蔽 扁 平 電 纜 T 距 離4 Insulating resin film 4 a Upper film 4b Lower film 5 Grounding tape 6 Reinforcing tape 7 Shielding film 11 Shielding flat cable 12 Cable end portion 13 Flat conductor 4 Insulating resin film 14a Upper film (first insulating resin film) 14b Lower side Film (second insulating resin film) 15 Grounding strap 15a Grounding strap (first grounding strap) 15b Grounding strap (second grounding strap) 15c Bending portion 15d First grounding strap portion 15e Second grounding strap portion 16 Reinforcing strip 17 Shielding Film 17a Shielding film 17b Shielding film 17c Bending portion 17d, 17e Shielding film 17f Front end-14-201034033 18a, 18b Low dielectric film 20 Ear 21 Shielding flat cable 22 Adhesive layer 23 Conductive layer 24 Next agent layer 25 Resin Layer 26 Shielding layer 27 Conductive bonding layer 28 Insulation layer 3 1 Shielding flat cable 41A, 41B Shielding flat cable T distance
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