541783 A7 經濟部智慧財產局員工消費合作社印製 _____B7_五、發明説明（1) 【技術領域】 本發明係關於音聲輸出用擴大器，例如，被設成能連 接於耳機受聽聲音之攜帶型電子機器具備之耳機擴大器等 所適用者。 【背景技術】 一般，CD(雷射磁碟）、MD(小型磁碟）、DVD(數位錄像 磁碟）等輕便型重放裝置，MP3 ( MPEG音頻唱機3 )或 ATRAC (Adaptive Transform Acoustic Coding)等對應之壓縮 方式攜帶音頻機器、攜帶電話或PDA ( Personal Digital Assistants )等移動機器等，乃大都被設成透過連接於該等 機器之耳機而輸出聲音。此時，爲了將再生之數位音頻資 料變換爲類比信號輸出至耳機，即使用DA變換器及耳機擴 大器。 圖1爲習知DA變換器及耳機擴大器之構成例示意圖。 該圖1，則在顯示將以下所述單位元方式之數位音頻資料變 換爲類比音頻信號予以輸出所需之構成。所謂單位元方式 ’卻是藉使用△ Σ調變以控制量化噪音，而比起現在廣範 使用之PCM方式，可使由數位資料恢復至原來類比信號之 伋原力加以提升之方式，最近特別受注目。 在圖1，係具備數位介面（I / F) 1，數位濾波器2及△ Σ 調變處理部3被構成爲D A變換器。又，以具備驅動器4、5 ，線圈LI、L2，電容器Cl、C3、C4、C5，電阻Rl、R3而被 構成爲耳機擴大器。 本紙張尺度適用中國國家標準（CNS ) A4規格（210X297公慶） (請先閲讀背面之注意事項再填寫本頁) -4 - 541783 A7 B7 經濟部智慧財產局員工消費合作社印製 五、發明説明（2) D A變換器乃以自C D等數位記錄媒体再生之數位音頻 資料爲根源予以生成調變信號。連接於D A變換器後段之耳 機擴大器，則依據該調變信號進行驅動，而藉使該調變信 號脈衝幅度所對應之量之電流予以流動，以獲得被放心之 類比音頻信號。 數位I / F 1卻是將未圖示數位記錄媒体等所再生之數 位單位元信號予以輸入者。數位濾波器2即對數位I / F 1所 輸入之單位元信號進行低通濾波處理，並將其結果向△ Σ 調變處理部3輸出。△ Σ調變處理部3乃對數位濾波器2之輸 出信號進行根據△ Σ調變之變換處理，而生成調變信號。 驅動器4、5則依據△ Σ調變處理部3輸出之調變信號進 行驅動，並輸出該調變信號脈衝幅度對應量之電流。一方 驅動器4爲擔當立体聲之左側（L)頻道，另一方驅動器5爲擔 當立体聲之右側（R)頻道。該等驅動器4、5卻由使用p MOS 電晶体及η MOS電晶体之開關擴大器（反相擴大器）所構成 〇 電源供應部6係向上述數位I / F 1，數位濾波器2， △ Σ調變處理部3及驅動器4、5供應電源電壓。此時，對於 成D Α變換器之數位I / F 1，數位濾波器2及Σ調變處理部3 即予以供應數位電源電壓（VDD、DGND )，對於構成耳機擴 大器之驅動器4、5即予以供應類比電源電壓（VCC、AGND ) 。攜帶型電子機器時，自電源供應部6向該等各電路供應之 電源卻自未圖示電池等獲取之。 線圈L 1及電容器C 1乃構成L頻道用之低通濾波器，線 (請先閱讀背面之注意事項再填寫本頁) 裝· -訂 参 本紙張尺度適用中國國家標準（CNS ) A4規格（210X297公釐） -5- 541783 A7 B7 五、發明説明（3) (請先閲讀背面之注意事項再填寫本頁) 圈L3及電容器C3則構成R頻道用之低通濾波器。又，由電 阻R1構成L頻道用之偏壓電路，由電阻R3構成R頻道用之 偏壓電路。通過該等低通濾波器生成之左右類比音頻信號 ，即分別介電容器C4、C5自輸出端子1 1被予以輸出。 現在被廣範使用之耳機係具有三組信號線（L頻道、R 頻道、接地），針對之，輸出端子1 1亦具有三個端子1 1 a〜 1 lc。第一端子1 la爲L頻道用，第二端子1 lb爲接地（GND) 用，R頻道用，第三端子11c爲R頻道用。第二端子lib連 接之接地線卻被左耳機12與右耳機13所共用。 將音頻信號自左右耳機12、13輸出時，乃需要使對於左 右耳機1 2、1 3之輸出信號以接地之零電壓爲中心搖擺於正負 。惟，如攜帶型機器所用電池，電源爲未具正負之直流單 一電源時，輸出電壓即以例如被偏壓於僅正側單邊之形態 搖擺。此時之輸出聲音則發不出低音，呈爲鏘鏘之聲音。 經濟部智慧財產局員工消費合作社印製 爲防止之，即需要裝設直流截止用電容器C4、C5。然 而’攜帶型電子機器所使用耳機之阻抗一般爲十數Ω〜數 十Ω之小。因此，欲使低頻率聲音正經輸出時，即需將直 流截止用電容器C4、C5之容量設成數百// F之大。此時， 電容器之外形即變爲非常龐大。 爲迴避之，一般雖採用將低頻率之低音予以放大以減 小直流截止用電容器之容量之方法，惟此時由於使頻率特 性變化’致難免音質之劣化。又，本方法，雖亦能小型化 直流截止用電容器’但並無法完全予以消失。於是，成爲 妨礙攜帶型電子機器之小型·輕量化或低成本化之主因。 本紙張尺度適用中國國家標準（CNS ) A4規格（210X297公釐） -6 - 541783 A7 B7 經濟部智慧財產局員工消費合作社印製 五、發明説明（4) 本發明乃爲解決如此問題所開發者，而以不必使用直 流截止用電容器，能使對於耳機之輸出電壓正負搖擺，藉 此謀取電子機器之小型·輕量化及低成本化爲目的。 【發明之開示】 本發明之音聲輸出用擴大器，係具有：被供應聲音信 號之第一信號線，與被供應將取得與上述聲音信號之差向 聲音輸出部輸出使用之基準信號的第二信號線，而以備有 可生成上述第一信號線之上述聲音信號放大用電源電壓之 中間電壓，且將該中間電壓當作上述第二信號線之上述基 準信號予以施加之中間電壓生成電路爲特徵。 本發明之其他形態，則以：具有依據電源電壓放大聲 音信號予以供給第一信號線之驅動器，與可生成上述電源 電壓之中間電壓，向供給對於上述聲音信號之基準信號所 需之第二信號線予以施加上述中間電壓之中間電壓生成電 路爲特徵。 本發明之其他形態，乃以：上述第一信號線含有爲供 應至少兩頻道分之聲音信號所需之兩條信號線，而上述被 供給第二信號線之基準信號，對於被供給上述兩條信號線 之上述兩頻道分之聲音信號則呈被共用爲特徵。 本發明之其他形態，卻以：上述中間電壓生成電路係 使用運算擴大器予以構成爲特徵。 例如，上述中間電壓生成電路具有將上述電源電壓予 以略1 / 2分壓之分壓電路，與將上述被分壓之電壓作爲輸 (請先閲讀背面之注意事項再填寫本頁) 本紙張尺度適用中國國家標準（CNS ) A4規格（210X297公釐） 541783 A7 B7 五、發明説明（5) 入而動作之運算擴大器。 (請先閲讀背面之注意事項再填寫本頁) 依據如上述構成之本發明，被輸出至第一信號線之聲 音信號，係被取得與被輸出至第二信號線之基準信號之差 ’而自例如耳機等之聲音輸出部予以放聲。此時，由於第 二信號線上經常被施加電源電壓之中間電壓，因此自聲音 輸出部視之，輸出電壓即似在（-電源電壓/ 2)〜（+電源電 壓/ 2)之間正負搖擺作動。於是，被供給聲音信號之第一 信號線上雖未裝設直流截止用電容器，亦能使對於聲音輸 出部之輸出電壓準確地正負搖擺。 又，依據被構成爲藉由運算擴大器生成基準信號之中 間電壓之本發明其他特徵，卻能自聲音輸出部觀察將第二 信號線之阻抗可忽視地予以趨小。因此，能抑制第二信號 線之電壓變動，將其電位經常維持於中間電壓。 【圖示之簡單說明】 圖1爲習知耳機擴大器之構成顯示圖。 經濟部智慧財產局員工消費合作社印製 圖2爲實施本發明音聲輸出擴大器之第一實施形態之耳 機擴大器構成例顯示圖。 圖3爲本實施形態之自耳機觀察之輸出電壓動作顯示圖 〇 圖4爲實施本發明音聲輸出擴大器之第二實施形態之耳 機擴大器構成例顯示圖。 圖5爲實施本發明音聲輸出擴大器之第三實施形態之耳 機擴大器構成例顯示圖。 本紙張尺度適用中國國家標準（CNS ) A4規格（210X297公釐） -8 - 541783 A7 B7 五、發明説明（6) 主要元件對照 1 數位介面（數位I/F) 2 數位濾波器 3 △ Σ調變處理部 4,5 驅動器 6 電源供應部 7 基準電壓發生電路 8 運算擴大器 11 輸出端子 12 左耳機 13 右耳機 14,15 電池 2 1,22,23,24,25,26 運算擴大器 31,32 運算擴大器 (讀先閲讀背面之注意事¾再填寫本頁〕 經濟部智慧財產局員工消費合作社印製 【發明之最佳實施形態】 (第一實施形態） 首先，就本發明第一實施形態參照圖示加以說明。 圖2爲實施本發明音聲輸出擴大器之第一實施形態之耳 機擴大器構成例顯示圖。在此，除了耳機擴大器以外，亦 顯示DA變換器之構成。又，在圖2，具有與圖1所示構成要 素相同功能之構成要素即付予相同之符號。 在圖2(a)’ 10爲1C晶片’具有數位Ι/p 1，數位滤波 本紙張尺度適用中國國家標準（CNS ) A4規格（210X 297公釐） -9- 541783 經濟部智慧財產局員工消費合作社印製 A7 B7五、發明説明（7) 器2，△ Σ調變處理部3，以D級擴大器動作之驅動器4、5 ，電源供應部6，基準電壓發生電路7，及以B級擴大器動 作之運算擴大器8。 數位I / F 1乃將自未圖示數位記錄媒体等被再生之數 位單位元信號輸入於IC晶片1 0內。此時，數位I / ρ 1即將 L頻道用數位資料與R頻道用數位資料以串行資料DIN之 形式交叉輸入。又，識別L頻道用數位資料與R頻道用數 位資料所需之時鐘LRCK，使L頻道用數位資料與R頻道用 數位資料同步所需之時鐘BCK等亦予以輸入。 數位濾波器2則對於由數位I / F 1輸入之單位元信號進 行低通濾波器處理，將其結果輸出至△ Σ調變處理部3。 △ Σ調變處理部3即對於自數位濾波器2輸出之信號進行根 據△ Σ調變之變換處理，而生成調變信號。 驅動器4、5係使用類比電源電壓VCC，將自△ Σ調變 處理部輸出之L頻道用及R頻道用調變信號加以放大，分 別向第一信號線〇UTL、OUTR輸出。一方驅動器4爲擔當L 頻道之聲音，另一方驅動器5爲擔當R頻道之聲音。該等驅 動器4、5卻由使用pMOS電晶体與nMOS電晶体之開關擴大 器加以構成。 電源供應部6乃對數位I / F 1，數位濾波器2，△ Σ調 變處理部3及驅動器4、5，以下所述基準電壓發生電路7及運 算擴大器8供應電源電壓。此時，對於構成DA變換器之數 位I / F 1，數位濾波器2及△ Σ調變處理部3予以供應數位 電源電壓（VDD、DGND)，對於構成耳機之驅動器4、5，基準 (請先閲讀背面之注意事項再填寫本頁) 本紙悵尺度適用中國國家標準（CNS ) A4規格（210X297公釐） -10- 541783 A7 ____B7 五、發明説明（8) 電壓發生電路7及運算擴大器8予以供應類比電源電壓（VCC 、AGND)。 攜帶型電子機器時，自電源供應部6向各電路供應之電 源，則由電池14或15獲取之。電池14爲數位電源電壓VDD 與類比電源電壓VCC均被設定於3.3V者。又，電池15爲數 位電源電壓VDD被設定於3.3V，類比電源電壓VCC被設定 於5V者。該等兩電池14、15卻可任意地交換使用。使用類 比電源電壓V C C較大之電池1 5時，由於被放大之聲音信號 之振幅會變大，致能獲得更高輸出。 基準電壓發生電路7，如圖2(b)所示，係由被串聯連接 於類比電源電壓VCC與類比用接地AGND間之相同電阻値 之兩個電阻R、R，與被並聯連接於一方電阻R之電容器C 所構成。基準電壓發生電路7即藉如此構成，生成類比電源 電壓VCC之1/2電位之中間電壓（VCC/ 2)予以輸出至運算 擴大器8之正端子。 運算擴大器8乃根據上述基準電壓發生電路7生成之中 間電壓進行放大動作，將上述中間電壓之信號作爲被供給 第一信號線OUTL、OUTR之L、R頻道聲音信號之基準信號 予以供給第二信號線COM。由於運算擴大器8之輸出被反饋 輸入於本身之負端子，故第二信號線COM被經常施加所定 之中間電壓（VCC / 2)。且由上述基準電壓發生電路7及運算 擴大器8構成本發明之中間電壓生成電路。 線圈L1及電容器C1爲構成L頻道聲音信號用之低通濾 波器，線圈L3及電容器C3爲構成R頻道聲音信號用之低通 本紙張尺度適用中國國家標準（CNS ) A4規格（210X29?公釐） --------^-裝-- (請先閱讀背面之注意事項再填寫本頁) 訂 經濟部智慧財產局員工消費合作社印製 -11 - 541783 經濟部智慧財產局員工消費合作社印製 A7 _B7___五、發明説明（9) 濾波器。又，電阻Rl、R2、R 3分別構成L頻道聲音信號用 之偏壓電路，基準信號用之偏壓電路，R頻道聲音信號用之 偏壓電路。 自驅動器4、5輸出之脈衝信號，則分別通過各自之低通 濾波器變爲L、R頻道之類比聲音信號，介輸出端子11a、 1 1 c被輸出至左耳機1 2及右耳機1 3。又，基準信號用之中間 電壓，即介輸出端子1 lb被輸出至左耳機12及右耳機13雙方 〇 左耳機12係取得自輸出端子11a供應之L頻道聲音信號 與自輸出端子1 1 b供應之中間電壓基準信號之差加以輸出。 又，右耳機13卻取得自輸出端子11c供應之R頻道聲音信號 與自輸出端子1 lb供應之中間電壓基準信號之差予以輸出。 如上構成耳機放大機時，由於第二信號線COM經常被 施加中間電壓VCC / 2，致例如L頻道被施加最大電壓VCC 時，自左耳機12視之，輸出電壓即呈向正側僅被搖擺+ VCC / 2 ( = VCC - VCC / 2 )。又，例如L頻道被施加最小之零 伏特（0V)時，自左耳機視之，輸出電壓即呈向負側僅被搖擺 —VCC / 2 (= 0 - VCC / 2 )。 即，如圖3所示，自左耳機言之，輸出電壓似在- VCC / 2〜+ VCC / 2之間被正負搖擺而動作。如此情形，右耳機 亦同。因此，.依據本實施形態，被供給L、R頻道聲音信號 之第一信號線〇UTL、OUTR上雖未設置直流截止用電容器 ，亦能使對左右耳機供應之輸出電壓予以正負搖擺。藉此 ，乃能省略習知必須之非常龐大之電容器，以圖攜帶型機 本紙張尺度適用中國國家標準（CNS ) A4規格（210X297公釐） (請先閲讀背面之注意事項再填寫本頁) -12- 541783 經濟部智慧財產局員工消費合作社印製 A7 __ B7五、發明説明（1) 器之小型·輕量化及低成本化。 又’在本實施形態，係將取得L、R頻道聲音信號之差 輸出至左右耳機時所使用基準信號之中間電壓（VCC / 2)， 非以與驅動器4、5同樣之開關擴大器，而是由運算擴大器8 加以生成。於是使用運算擴大器8時，自左右耳機視12、13 之’能將第二信號線COM之阻抗可忽視程度地予以趨小。 雖亦可考慮將開關擴大器輸出之佔空率50%脈衝藉由 LC濾波器加以平滑化以生成中間電壓（VCC / 2)之方法，惟 此時，由於自第二信號線COM觀看時之阻抗會變大，致對 於第二信號線COM之輸出電壓隨著流動之電流而大爲變動 〇 因此，L頻道與R頻道之分離轉惡，會發生L、R頻道 聲音信號之一方混入另方之不妥。又，開關擴大器由於輸 出脈衝，以致雖予以平滑2化亦某程度會發生噪音，而產生 S/N變爲不佳之不妥。 針對之，如本實施形態藉使用運算擴大器8進行線性放 大動作，則能抑制第二信號線COM之電壓變動，將其電位 經常維持於VCC / 2。藉此，能將L頻道與R頻道之分離及 S / N保持於良好同時，能使對於左右耳機之輸出電壓準確 地正負搖擺。 是此，使用運算擴大器8時，比起使用LC濾波器等平 滑化電路予以生成中間電壓時，能實現更高之性能。因此 ，運算擴大器8之構成以簡易即可，不必增大晶片面積亦內 藏運算擴大器8。 本紙張尺度適用中國國家標準（CNS ) A4規格（210X297公釐） (請先閲讀背面之注意事項再填寫本頁) -13 - 541783 經濟部智慧財產局員工消費合作社印製 A7 B7五、發明説明（1) 又，本實施形態時，對於左右耳機1 2、1 3之輸出電壓係 在一 VCC/ 2〜+ VCC / 2之範圍被正負搖擺，比起習知之在 一 VCC〜+ VCC之範圍正負搖擺，其輸出功率已下降。惟 ，就以CD / MD / DVD重放裝置，MP3或ATRAC對應之攜 帶音頻機器，攜帶電話或PDA等移動機器，自左右耳機12 、i 3聽取聲音而言，如有本實施形態程度之輸出功率即足夠 。又，如盼望時，藉使用電池1 5及可獲得更大輸出。 (第二實施形態） 其次，說明本發明第二實施形態。第二實施形態係將 使用爲耳機擴大器之擴大器僅由B級擴大器加以構成之例 示。本第二實施形態，亦可適用於PCM方式或單位元方式 之任一方式。 圖4爲第二實施形態之耳機擴大器構成例顯示圖。在圖 4，以類比電源電壓VCC係使用12V。Rll、R12爲分壓用電 阻，互相具有相同電阻値。又，與電阻R 1 2並聯連接有電容 器C2 1。藉此，電阻R 1 1、R 1 2之中間結點即出現類比電源 電壓VCC被1 / 2分壓之中間電壓VCC / 2。 運算擴大器21係將該分壓所生成中間電壓VCC/ 2作爲 向正端子之輸入而動作。該運算擴大器21之輸出卻被反饋 輸入於本身之負端子。且藉此，運算擴大器21即穩定供應 VCC / 2= 6V之電壓。 另，自信號線INL、INR輸入之L頻道聲音信號及R頻 道聲音信號乃介直流截止用電容器Cl 1、C1 2被輸入於運算 本紙張尺度適用中國國家標準（CNS ) A4規格（210X297公釐） (請先閱讀背面之注意事項再填寫本頁) -14 - 541783 經濟部智慧財產局員工消費合作社印製 A7 B7五、發明説明（ 擴大器22、23。各運算擴大器22、23之輸入段則設有偏壓用 電阻R 1 5、R 1 6，運算擴大器2 1之輸出信號即被供給於此。 該等偏壓電阻Ri5、R16卻使用較大電阻値（例如100ΚΩ )。如是，藉在各運算擴大器22、23之輸入段予以設置高電 阻偏壓電路，而促使運算擴大器22、23之正端子呈高阻抗。 於是，不需直流截止用電容器Cll、C12設成大容量，亦能 使低頻聲音信號通過。即，電容器C 1 1、C 1 2之容量頂多爲1 # F (例如0.1 // F)即足夠。 在上述運算擴大器22、23被放大之L、R頻道聲音信號 係介電阻R25、R26被輸入於次段運算擴大器24、26之負端 子。該等運算擴大器24、26卻以反相擴大器動作，將其放大 信號予以輸出至第一信號線〇UTL、OUTR。此時，自各運 算擴大器24、26輸出之聲音信號即隨著被供給各運算擴大器 24、26控制端之電源電壓VCC搖擺於0〜12V之間。 運算擴大器25乃將自上述算擴大器2 1供應之中間電壓 VCC / 2作爲正端子之輸入而動作。該運算擴大器25之輸入 亦1反饋輸入於本身之負端子。藉此，運算擴大器25能穩定 地將VCC / 2 = 6V之中間電壓供給第二信號線c〇M。 如此予以構成時，如同第一實施形態，自耳機試之， 輸出電壓似在—VCC / 2〜+ VCC / 2之間被正負搖擺動作。 因此，在被供給L、R頻道聲音信號之第一信號線〇UTL、 01JTR上雖未設置直流截止用電容器，亦能使對於耳機之輸 出電壓搖擺於正負。藉此，能省略習知必須之非常龐大電 容器。 本紙張尺度適用中國國家標準（CNS ) A4規格（210X297公釐） ~ ~ ""一 -15- (請先閲讀背面之注意事項再填寫本頁) 541783 A7 _ B7 ________ 五、發明説明（Ο 又，在本實施形態，由於僅使用運算擴大器，因此自 耳機觀察能將第二信號線COM之阻抗可忽視地予以趨小。 藉此，能抑制第二信號線COM之電壓變動，將L頻道與R 頻道之分離及S / N保持於良好同時，尙能使對於耳機之輸 出電壓準確地正負搖擺。 (第三實施形態） 其次，就本發明第三實施形態加以說明。本第三實施 形態，亦可適用於PCM方式或單位元方式之任一方式。 圖5爲第三實施形態之耳機擴大器構成例顯示圖。在圖 5，與圖4所示構成要素具相同功能之構成要素即付予相同 符號，並省略重複說明。 在圖5所示第三實施形態，係替代圖4所示運算擴大器 26，使用兩個運算擴大器31、32。運算擴大器31即將L頻道 用運算擴大器25之輸出信號作爲負端子之輸入而動作。又 ，運算擴大器32則以R頻道用運算擴大器26之輸出信號作 爲負端子之輸入而動作。亦即，該等運算擴大器31、32亦以 反相擴大器動作。 運算擴大器25乃將被搖擺於0〜12V間之L頻道聲音信 號輸出至信號線OUTL-，運算擴大器31卻將與輸出至信號 線OUTL -之輸出信號相位反轉之L頻道聲音信號輸出至信 號線OUTL +。在本實施形態，即取該等輸出至信號線 〇UTL_ 、〇UTL+之聲音信號之差予以輸出至左耳機。 又，運算擴大器27則將被搖擺於0〜12V間之R頻道聲 本纸張尺度適用中國國家標準（CNS ) A4規格（210X297公釐） ' —~ -16- --------裝-- (請先閱讀背面之注意事項再填寫本頁) 訂 經濟部智慧財產局員工消費合作社印製 541783 _________ 五、發明説明（1合 (請先閲讀背面之注意事項再填寫本頁) 音信號輸出至信號線OUTR-，運算擴大器32卻將與輸出至 信號線OUTR -之輸出信號相位反轉之R頻道聲音信號輸出 至信號線OUTR +。在本實施形態，即取該等輸出至信號線 OUTR— 、OUTR+之聲音信號之差予以輸出至右耳機。 此時，例如L頻道一方信號線OUTL -之輸出電壓爲最 大之12V時，另方信號線〇UTL +之輸出電壓即呈0V，被付 與左耳機之電壓差卻呈12V。又，一方信號線OUTL -之輸 出電壓爲最小之0V時，另方信號線OUTL +之輸出電壓即 呈1 2 V ’被付與左耳機之電壓差卻呈-1 2 V。因此，以左耳 機視之，輸出電壓似在-12V〜+ 12V( - VCC〜+ VCC)間被 正負搖擺動作。右耳機亦與此相同。 如上，依據第三實施形態，由於對於耳機之輸出端子 需要四個以致缺乏通用性，惟與第二實施形態相比，卻具 有能獲得兩倍左右之大輸出功率之優點。 經濟部智慧財產局員工消費合作社印製 又，在上述第一實施形態〜第三實施形態，雖使用基 準電壓發生電路7或分壓用電阻Rll、R12作爲發生電源電壓 VCC之中間電壓所需構成，惟本發明並非被限定於此。即 ，只要是能發生中間電壓之構成，則均可加以適用。 又’在上述第一及第二實施形態，雖將供給第二信號 線COM之電壓設爲類比電源電壓VCC之剛好1 / 2之電壓， 惟嚴密說之，非1 / 2亦可。即，只要是能獲得所盼振幅電 壓以上，則稍爲偏移GND側或VCC側亦可 又，上述第--第三實施形態，雖就具L、R兩頻道之 立体聲音對應之耳機加以說明，但單耳對應之耳機等亦同 本紙張尺度適用中國國家標準（CNS ) A4規格（210X 297公釐） -17- 541783 A7 B7 五、發明説明（1令 樣可適合本發明。乂 ’上述實施形態雖以具有左右耳機1 2、 i 3爲例子進行說明，惟亦可適用於僅具一個聲音輸出部之 耳機。 (請先閱讀背面之注意事項再填寫本頁) 又’上述第--第三實施形態，雖被適用於特別盼望 小型·輕量化等之攜帶型電子機器較宜，惟不必多言，當 然亦可適用於擱置型電子機器。 另外，上述說明各實施形態，僅不過是實施本發明之 具体化一例示而已，並不得藉該等加以限定性解釋本發明 之技術範圍。即，本發明不脫逸其精神、或其主要特徵， 能以各種形態加以實施。 經濟部智慧財產局員工消費合作社印製 如上所作詳細說明，依據本發明，藉向第二信號線上 予以施加電源電壓之中間電壓，而自聲音輸出部視之能促 使輸出電壓似在（-電源電壓/ 2)〜（+電源電壓/ 2)間被正 負搖擺作動。藉此，雖在被供應聲音信號之第一信號線上 未設置直流截止用電容器，亦能使對於聲音輸出部之輸出 電壓正負搖擺。於是，能省略習知爲輸出低頻聲音所必須 之非常龐大電容器，以圖電子機器之小型·輕量化及低成 本化。 又，依據本發明之其他特徵，由於將基準信號之中間 信號由運算擴大器加以生成，因此能將第二信號線之阻抗 自聲音輸出部觀察可予以忽視趨小。且藉此，能抑制第二 信號線之電壓變動，將其電位經常維持於中間電壓。於是 ，將本發明適用於具L、R兩頻道之立体聲音時，能將其左 右頻道之分離及S / N保持於良好同時，亦能使左右耳機之 本紙張尺度適用中國國家標準（CNS ) A4規格（210X297公釐） -18- 541783 A7 ______ ______ B7_ 五、發明説明（ 蝓出電壓準確地搖擺於正負。 【產業上之可利用性】 本發明，係對於不必使用直流截止用電容器，能使對 於耳機之輸出電壓正負搖擺，藉此謀圖電子機器之小型· 輕量化及低成本化頗爲有用。 (請先閱讀背面之注意事項再填寫本頁) 經濟部智慧財產局員工消費合作社印製 一張 一紙 本 A Ns c 一準 一標 一家 ~國 國 一中 用 |適541783 A7 Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs _____B7_ V. Description of the Invention (1) [Technical Field] The present invention relates to an amplifier for sound output, for example, it is set to be able to connect to headphones Applicable to headphone amplifiers and the like included in portable electronic devices. [Background Art] Generally, portable playback devices such as CD (laser disk), MD (small disk), DVD (digital video disk), MP3 (MPEG audio player 3) or ATRAC (Adaptive Transform Acoustic Coding) Corresponding compression methods carry audio equipment, mobile phones, or mobile devices such as PDAs (Personal Digital Assistants), and most are set to output sound through headphones connected to these devices. At this time, in order to convert the reproduced digital audio data into an analog signal and output it to the headphones, a DA converter and a headphone amplifier are used. FIG. 1 is a schematic diagram of a configuration example of a conventional DA converter and a headphone amplifier. This figure 1 shows the structure required to convert the digital audio data in the unit element method described below into an analog audio signal and output it. The so-called unit element method is to control the quantization noise by using △ Σ modulation. Compared with the widely used PCM method, the digital data can be restored to the original analog signal and the original force can be improved. Attention. In FIG. 1, a digital interface (I / F) 1 is provided, a digital filter 2 and a ΔΣ modulation processing unit 3 are configured as a DA converter. Furthermore, the headphone amplifier is constituted by including drivers 4 and 5, coils LI and L2, capacitors C1, C3, C4, and C5, and resistors R1 and R3. This paper size applies to China National Standard (CNS) A4 specification (210X297 public holiday) (Please read the notes on the back before filling out this page) -4-541783 A7 B7 Printed by the Consumers ’Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs (2) The DA converter generates modulation signals based on digital audio data reproduced from digital recording media such as CDs. The headphone amplifier connected to the rear of the DA converter is driven according to the modulation signal, and the current corresponding to the amplitude of the modulation signal pulse is flowed to obtain a reassured analog audio signal. The digital I / F 1 is input to a digital unit signal reproduced from a digital recording medium, etc., not shown. The digital filter 2 performs low-pass filtering on the unit element signal input from the digital I / F 1 and outputs the result to the ΔΣ modulation processing unit 3. The delta-sigma modulation processing unit 3 performs a transformation process on the output signal of the digital filter 2 according to the delta-sigma modulation to generate a modulation signal. Drivers 4 and 5 are driven according to the modulation signal output from the ΔΣ modulation processing unit 3, and output a current corresponding to the amplitude of the modulation signal pulse. One driver 4 is the left (L) channel serving as stereo, and the other driver 5 is the right (R) channel serving as stereo. These drivers 4 and 5 are composed of a switching amplifier (inverting amplifier) using a p MOS transistor and an η MOS transistor. The power supply unit 6 sends the digital I / F 1, digital filter 2, and △. The Σ modulation processing unit 3 and the drivers 4 and 5 supply a power supply voltage. At this time, for the digital I / F 1 of the D A converter, the digital filter 2 and the sigma modulation processing section 3 supply the digital power supply voltage (VDD, DGND), and for the drivers 4, 5 constituting the headphone amplifier, Analog power supply voltages (VCC, AGND) are supplied. In the case of a portable electronic device, the power supplied from the power supply unit 6 to these circuits is obtained from a battery or the like (not shown). The coil L 1 and the capacitor C 1 are low-pass filters for the L channel. The wires (please read the precautions on the back before filling out this page). Installation--This paper applies the Chinese national standard (CNS) A4 specification ( 210X297mm) -5- 541783 A7 B7 V. Description of the invention (3) (Please read the precautions on the back before filling this page) Loop L3 and capacitor C3 constitute the low-pass filter for the R channel. A resistor R1 constitutes a bias circuit for the L channel, and a resistor R3 constitutes a bias circuit for the R channel. The left and right analog audio signals generated by these low-pass filters, namely, the capacitors C4 and C5 are output from the output terminals 11 respectively. The earphones currently used by Guangfan have three sets of signal lines (L channel, R channel, and ground). For this, the output terminal 11 also has three terminals 1 1 a to 1 lc. The first terminal 11a is used for the L channel, the second terminal 1lb is used for the ground (GND), the R channel is used, and the third terminal 11c is used for the R channel. The ground wire connected to the second terminal lib is shared by the left earphone 12 and the right earphone 13. When outputting audio signals from the left and right earphones 12, 13, it is necessary to make the output signals for the left and right earphones 1, 2, and 3 swing around positive and negative with the grounded zero voltage as the center. However, if the battery used in a portable machine is a single DC power supply with no positive or negative power, the output voltage is, for example, oscillated by being biased on only one side of the positive side. At this time, the output sound cannot produce bass sound, and it is a gurgling sound. Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs To prevent this, it is necessary to install DC cut-off capacitors C4 and C5. However, the impedance of a headphone used in a 'portable electronic device is generally several tens to several tens Ω. Therefore, if low-frequency sound is to be outputted in a straightforward manner, it is necessary to set the capacity of the DC-cut capacitors C4 and C5 to several hundreds / F. At this time, the shape of the capacitor becomes very large. In order to avoid this, although a method of amplifying low-frequency bass to reduce the capacity of the DC-cut capacitor is generally adopted, the quality of the sound is inevitably deteriorated due to the change of the frequency characteristics. In addition, although this method can reduce the size of the DC-cut capacitor, it cannot be completely eliminated. As a result, it has become a major factor preventing the miniaturization, weight reduction, and cost reduction of portable electronic devices. This paper size applies the Chinese National Standard (CNS) A4 specification (210X297 mm) -6-541783 A7 B7 Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs 5. Description of the invention (4) The present invention was developed to solve such a problem Instead of using a DC cut-off capacitor, the output voltage of the headphone can be swinged positively or negatively, thereby achieving the miniaturization, weight reduction, and cost reduction of the electronic device. [Invention of the invention] The sound output amplifier of the present invention includes a first signal line to which a sound signal is supplied, and a first signal line to which a reference signal used for outputting a difference from the sound signal to the sound output unit is supplied and used. Two signal lines, and an intermediate voltage generating circuit that generates an intermediate voltage of the power signal voltage for amplifying the sound signal of the first signal line, and applies the intermediate voltage as the reference signal of the second signal line As a feature. In another aspect of the present invention, a driver having an audio signal amplified in accordance with a power supply voltage and supplying it to the first signal line, and an intermediate voltage capable of generating the power supply voltage, and supplying a second signal required for the reference signal of the audio signal is provided. The line is characterized by an intermediate voltage generating circuit to which the intermediate voltage is applied. In another aspect of the present invention, the first signal line includes two signal lines required to supply at least two channels of sound signals, and the reference signal supplied to the second signal line is provided to the two The two channel audio signals of the signal line are characterized by being shared. Another aspect of the present invention is characterized in that the intermediate voltage generating circuit is configured using an arithmetic amplifier. For example, the above intermediate voltage generating circuit has a voltage dividing circuit that divides the power supply voltage by a factor of 1/2, and uses the divided voltage as input (please read the precautions on the back before filling this page). The scale is applicable to the Chinese National Standard (CNS) A4 specification (210X297 mm) 541783 A7 B7 V. Description of the invention (5) Operational amplifier that moves in and out. (Please read the precautions on the back before filling this page.) According to the present invention configured as described above, the sound signal output to the first signal line is the difference between the reference signal output and the reference signal output to the second signal line. The sound is output from a sound output section such as headphones. At this time, since the middle voltage of the power supply voltage is often applied to the second signal line, the output voltage seems to swing between positive and negative between (-power supply voltage / 2) ~ (+ power supply voltage / 2). . Therefore, although the DC cut-off capacitor is not installed on the first signal line to which the sound signal is supplied, the output voltage to the sound output portion can be accurately swung positively and negatively. In addition, according to other features of the present invention that are configured to generate a reference signal intermediate voltage by an arithmetic amplifier, the impedance of the second signal line can be negligibly reduced as viewed from the sound output section. Therefore, it is possible to suppress the voltage fluctuation of the second signal line and maintain the potential thereof at an intermediate voltage. [Brief description of the diagram] FIG. 1 is a structural display diagram of a conventional headphone amplifier. Printed by the Consumer Cooperative of Intellectual Property Bureau of the Ministry of Economic Affairs Fig. 2 is a diagram showing an example of the structure of a headphone amplifier that implements the first embodiment of the sound output amplifier of the present invention. Fig. 3 is an operation voltage display diagram of the output voltage observed from the earphone according to this embodiment. Fig. 4 is a display diagram showing an example of the structure of the earphone amplifier implementing the second embodiment of the sound output amplifier of the present invention. Fig. 5 is a diagram showing a configuration example of a headphone amplifier according to a third embodiment of the sound output amplifier of the present invention. This paper scale applies Chinese National Standard (CNS) A4 specification (210X297mm) -8-541783 A7 B7 V. Description of the invention (6) Comparison of main components 1 Digital interface (digital I / F) 2 Digital filter 3 △ Σ adjustment Variable processing unit 4, 5 driver 6 power supply unit 7 reference voltage generating circuit 8 arithmetic amplifier 11 output terminal 12 left earphone 13 right earphone 14, 15 battery 2 1, 22, 23, 24, 25, 26 arithmetic amplifier 31, 32 Computational Amplifier (Read the notes on the back first, and then fill out this page) Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs [Best Embodiment of Invention] (First Embodiment) First, the first implementation of the present invention The form will be described with reference to the figure. Fig. 2 is a diagram showing a configuration example of a headphone amplifier implementing the first embodiment of the sound output amplifier of the present invention. Here, in addition to the headphone amplifier, the configuration of a DA converter is also shown. In Fig. 2, components having the same functions as those shown in Fig. 1 are given the same symbols. In Fig. 2 (a), '10 is a 1C chip 'has a digital 1 / p 1, and digital filtering is suitable for this paper. China National Standard (CNS) A4 specification (210X 297 mm) -9- 541783 Printed by the Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs A7 B7 V. Invention description (7) Device 2, △ Σ modulation processing unit 3, with D Drivers 4 and 5 for stage amplifier operation, power supply unit 6, reference voltage generating circuit 7, and arithmetic amplifier 8 for stage B amplifier operation. Digital I / F 1 is used for digital recording media (not shown). The reproduced digital unit meta signal is input into the IC chip 10. At this time, the digital I / ρ 1 cross-inputs the digital data for the L channel and the digital data for the R channel in the form of serial data DIN. Also, it is used to identify the L channel. The clock LRCK required for the digital data and the digital data for the R channel, and the clock BCK required to synchronize the digital data for the L channel with the digital data for the R channel are also input. The digital filter 2 is input for the digital I / F 1 input. The unit element signal is processed by a low-pass filter, and the result is output to the Δ Σ modulation processing unit 3. The Δ Σ modulation processing unit 3 performs a conversion process on the signal output from the digital filter 2 according to the Δ Σ modulation While generating modulation Drivers 4 and 5 use analog power supply voltage VCC to amplify the modulation signals for L channel and R channel output from the △ Σ modulation processing unit, and output them to the first signal lines OUTL and OUTR respectively. One driver 4 is the sound of the L channel, and the other driver 5 is the sound of the R channel. These drivers 4 and 5 are composed of a switching amplifier using a pMOS transistor and an nMOS transistor. The power supply unit 6 is a digital I / F 1, digital filter 2, delta-sigma modulation processing unit 3, and drivers 4, 5 and the reference voltage generating circuit 7 and the arithmetic amplifier 8 described below supply power voltage. At this time, the digital power supply voltage (VDD, DGND) is supplied to the digital I / F 1, the digital filter 2 and the delta-sigma modulation processing unit 3 constituting the DA converter. Please read the notes on the back before filling this page) The paper size is applicable to Chinese National Standard (CNS) A4 specification (210X297mm) -10- 541783 A7 ____B7 V. Description of the invention (8) Voltage generating circuit 7 and operation amplifier 8 Supply analog power supply voltage (VCC, AGND). In the case of a portable electronic device, the power supplied to each circuit from the power supply section 6 is obtained by the battery 14 or 15. The battery 14 is a digital power supply voltage VDD and an analog power supply voltage VCC are both set to 3.3V. The battery 15 has a digital power supply voltage VDD of 3.3V and an analog power supply voltage VCC of 5V. However, the two batteries 14, 15 can be exchanged arbitrarily. When a battery 15 having a large analog power supply voltage V C C is used, the amplitude of the amplified sound signal becomes larger, so that a higher output can be obtained. As shown in FIG. 2 (b), the reference voltage generating circuit 7 is composed of two resistors R, R connected in series between the analog power supply voltage VCC and the analog ground AGND, and two resistors R and R connected in parallel. It is composed of a capacitor C of R. The reference voltage generating circuit 7 is thus configured to generate an intermediate voltage (VCC / 2) of 1/2 the potential of the analog power supply voltage VCC and output it to the positive terminal of the operational amplifier 8. The arithmetic amplifier 8 performs an amplification operation based on the intermediate voltage generated by the reference voltage generating circuit 7 and supplies the signal of the intermediate voltage as a reference signal to the L and R channel sound signals supplied to the first signal lines OUTL and OUTR. Signal line COM. Since the output of the operational amplifier 8 is fed back to its own negative terminal, a predetermined intermediate voltage (VCC / 2) is always applied to the second signal line COM. The reference voltage generating circuit 7 and the arithmetic amplifier 8 constitute the intermediate voltage generating circuit of the present invention. Coil L1 and capacitor C1 are low-pass filters for L-channel sound signals, and coil L3 and capacitor C3 are low-pass for R-channel sound signals. The paper size is applicable to Chinese National Standard (CNS) A4 specifications (210X29? Mm) ) -------- ^-Pack-(Please read the notes on the back before filling out this page) Order printed by the Intellectual Property Bureau's Consumer Cooperatives of the Ministry of Economic Affairs -11-541783 Employee Intellectual Property Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs Print A7 _B7___ V. Description of the invention (9) Filter. The resistors R1, R2, and R3 respectively constitute a bias circuit for the L-channel sound signal, a bias signal for the reference signal, and a bias circuit for the R channel sound signal. The pulse signals output from drivers 4 and 5 are respectively converted into analog sound signals of L and R channels through their respective low-pass filters, and the output terminals 11a and 1 1 c are output to the left earphone 12 and the right earphone 1 3 . In addition, the intermediate voltage for the reference signal, that is, the output terminal 1 lb is output to both the left earphone 12 and the right earphone 13. The left earphone 12 is obtained from the L channel sound signal supplied from the output terminal 11a and supplied from the output terminal 1 1 b. The difference between the intermediate voltage reference signals is output. In addition, the right earphone 13 obtains the difference between the R channel sound signal supplied from the output terminal 11c and the intermediate voltage reference signal supplied from the output terminal 1lb and outputs it. When the headphone amplifier is configured as above, the second signal line COM is often applied with an intermediate voltage VCC / 2. For example, when the maximum voltage VCC is applied to the L channel, the output voltage is viewed from the left earphone 12 and is only swayed to the positive side. + VCC / 2 (= VCC-VCC / 2). In addition, for example, when the minimum zero volt (0V) is applied to the L channel, the output voltage is only swinging to the negative side when viewed from the left earphone-VCC / 2 (= 0-VCC / 2). In other words, as shown in FIG. 3, from the left earphone, the output voltage appears to swing between positive and negative-VCC / 2 ~ + VCC / 2 to operate. In this case, the same goes for the right earphone. Therefore, according to this embodiment, although the first signal lines OUTL and OUTR to which the sound signals of the L and R channels are supplied are not provided with a DC cut-off capacitor, the output voltages of the left and right earphones can also be swinged positively and negatively. By this, it is possible to omit the very large capacitors that are necessary for conventional use. The paper size of the portable machine is applicable to the Chinese National Standard (CNS) A4 specification (210X297 mm) (Please read the precautions on the back before filling this page) -12- 541783 Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs A7 __ B7 V. Description of Invention (1) The size, weight and cost of the device. Also, in this embodiment, the intermediate voltage (VCC / 2) of the reference signal used when the difference between the sound signals of the L and R channels is output to the left and right earphones is not a switch amplifier that is the same as that of the drivers 4 and 5. It is generated by the operation amplifier 8. Therefore, when the operational amplifier 8 is used, the impedance of the second signal line COM can be reduced to a negligible degree from the perspective of the left and right earphones 12, 13 ,. Although a method of smoothing the 50% duty cycle output of the switching amplifier by an LC filter to generate an intermediate voltage (VCC / 2) can also be considered, at this time, due to the The impedance will increase, causing the output voltage of the second signal line COM to vary greatly with the current flowing. Therefore, the separation of the L channel and the R channel becomes bad, and one of the L and R channel sound signals will mix into the other Not right. In addition, because the switching amplifier outputs a pulse, noise may occur to some extent even if it is smoothed and the S / N becomes unfavorable. In contrast, if a linear amplification operation is performed by using the arithmetic amplifier 8 in this embodiment, the voltage variation of the second signal line COM can be suppressed and its potential can be constantly maintained at VCC / 2. In this way, the separation between the L channel and the R channel and the S / N can be maintained at the same time, and the output voltages of the left and right headphones can be accurately swinged. For this reason, when the operational amplifier 8 is used, higher performance can be achieved than when an intermediate voltage is generated using a smoothing circuit such as an LC filter. Therefore, the configuration of the arithmetic amplifier 8 can be simplified, and it is not necessary to increase the chip area, and the arithmetic amplifier 8 is built in. This paper size applies Chinese National Standard (CNS) A4 specification (210X297 mm) (Please read the precautions on the back before filling out this page) -13-541783 Printed by the Consumers ’Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs A7 B7 V. Invention Description (1) In this embodiment, the output voltages of the left and right earphones 1, 2, and 13 are swinging in the range of VCC / 2 to + VCC / 2, which is positive and negative, compared to the range of 1 VCC to + VCC as is known. Positive and negative swing, its output power has decreased. However, in the case of CD / MD / DVD playback devices, MP3 or ATRAC corresponding portable audio devices, mobile phones or PDAs and other mobile devices, listening to the sound from the left and right earphones 12 and i 3, if there is an output of this embodiment Power is sufficient. Also, as expected, by using the battery 15 and greater output. (Second Embodiment) Next, a second embodiment of the present invention will be described. The second embodiment is an example in which an amplifier used as a headphone amplifier is composed of only a B-stage amplifier. The second embodiment is also applicable to either the PCM method or the unit cell method. Fig. 4 is a diagram showing a configuration example of a headphone amplifier according to a second embodiment. In Figure 4, the analog power supply voltage VCC is used at 12V. Rll and R12 are resistors for voltage division and have the same resistance 互相. A capacitor C2 1 is connected in parallel with the resistor R 1 2. As a result, the intermediate node of the resistors R 1 1 and R 1 2 becomes the intermediate voltage VCC / 2 of the analog power supply voltage VCC divided by 1/2. The arithmetic amplifier 21 operates as an intermediate voltage VCC / 2 generated by the divided voltage as an input to the positive terminal. The output of the operational amplifier 21 is fed back to its own negative terminal. And by this, the arithmetic amplifier 21 stably supplies a voltage of VCC / 2 = 6V. In addition, the L channel sound signals and R channel sound signals input from the signal lines INL and INR are input to the DC cut-off capacitors Cl 1 and C1 2 for calculation. The paper size applies the Chinese National Standard (CNS) A4 specification (210X297 mm). (Please read the precautions on the back before filling out this page) -14-541783 Printed by A7 B7, Consumer Cooperatives, Intellectual Property Bureau, Ministry of Economic Affairs V. Invention Description (Amplifiers 22 and 23. Input sections for each calculation amplifier 22, 23 The bias resistors R 1 5 and R 1 6 are provided, and the output signal of the arithmetic amplifier 21 is supplied here. These bias resistors Ri 5 and R 16 use larger resistors 例如 (for example, 100KΩ). If yes, By providing a high-resistance bias circuit at the input sections of each of the operational amplifiers 22 and 23, the positive terminals of the operational amplifiers 22 and 23 are caused to have a high impedance. Therefore, it is not necessary to set the DC cut-off capacitors C11 and C12 to be large. The capacity can also pass low-frequency sound signals. That is, the capacity of the capacitors C 1 1 and C 1 2 is at most 1 # F (for example, 0.1 // F) is sufficient. The sound signals of channel R are dielectric resistances R25 and R2 6 is input to the negative terminals of the secondary operation amplifiers 24 and 26. However, these operation amplifiers 24 and 26 operate as inverting amplifiers and output their amplified signals to the first signal lines OUTL and OUTR. At this time The audio signal output from each of the arithmetic amplifiers 24 and 26 swings between 0 and 12 V as the power supply voltage VCC supplied to the control terminals of each of the arithmetic amplifiers 24 and 26. The arithmetic amplifier 25 is a signal from the arithmetic amplifier 2 described above. The intermediate voltage VCC / 2 supplied by 1 operates as the input of the positive terminal. The input of the operational amplifier 25 is also fed back to its negative terminal. By this, the operational amplifier 25 can stably change VCC / 2 = 6V. The intermediate voltage is supplied to the second signal line coM. When configured in this way, as in the first embodiment, the output voltage seems to be positively and negatively oscillated between -VCC / 2 ~ + VCC / 2 as tested in the first embodiment. The first signal lines 〇UTL and 01JTR to which the sound signals of the L and R channels are supplied, although no DC cut-off capacitor is provided, can also swing the output voltage of the headphones to positive and negative. This can eliminate the very large capacitors that are necessary for conventional use. . This paper The dimensions are applicable to the Chinese National Standard (CNS) A4 specification (210X297 mm) ~ ~ " " 一 -15- (Please read the precautions on the back before filling this page) 541783 A7 _ B7 ________ V. Description of the invention In this embodiment, since only the operational amplifier is used, the impedance of the second signal line COM can be negligibly reduced from the earphone observation. This can suppress the voltage variation of the second signal line COM and reduce the L channel. Separate from the R channel and keep S / N at the same time, it can make the output voltage of the headphones accurately swing positive and negative. (Third Embodiment) Next, a third embodiment of the present invention will be described. The third embodiment is also applicable to either the PCM method or the unit cell method. Fig. 5 is a diagram showing a configuration example of a headphone amplifier according to a third embodiment. In FIG. 5, the same reference numerals are given to the constituent elements having the same functions as the constituent elements shown in FIG. 4, and repeated description is omitted. In the third embodiment shown in Fig. 5, instead of the arithmetic amplifier 26 shown in Fig. 4, two arithmetic amplifiers 31 and 32 are used. The arithmetic amplifier 31 operates the output signal of the L channel using the arithmetic amplifier 25 as an input of a negative terminal. The arithmetic amplifier 32 operates with the output signal of the R channel arithmetic amplifier 26 as the input of the negative terminal. That is, the operational amplifiers 31 and 32 also operate as inverting amplifiers. The arithmetic amplifier 25 outputs the L-channel sound signal swinging between 0 and 12V to the signal line OUTL-, while the arithmetic amplifier 31 outputs the L-channel sound signal whose phase is inverted from the output signal output to the signal line OUTL- To signal line OUTL +. In this embodiment, the difference between the sound signals output to the signal lines 〇UTL_ and 〇UTL + is output to the left earphone. In addition, the operational amplifier 27 will be oscillated between 0 ~ 12V. The paper size of this paper applies the Chinese National Standard (CNS) A4 specification (210X297 mm). '~~ -16- ------- -Install-(Please read the precautions on the back before filling this page) Order printed by the Intellectual Property Bureau of the Ministry of Economic Affairs's Consumer Cooperatives 541783 _________ 5. Description of the invention (1 in (Please read the precautions on the back before filling out this page) The audio signal is output to the signal line OUTR-, but the arithmetic amplifier 32 outputs the R channel sound signal whose phase is inverted to the output signal output to the signal line OUTR- to the signal line OUTR +. In this embodiment, these outputs are taken The difference between the sound signals to the signal lines OUTR— and OUTR + is output to the right earphone. At this time, for example, when the output voltage of one signal line OUTL-of the L channel is a maximum of 12V, the output voltage of the other signal line OUTL + is displayed. 0V, the voltage difference between the left earphone and the left earphone is 12V. Moreover, when the output voltage of one signal line OUTL-is the smallest 0V, the output voltage of the other signal line OUTL + is 1 2 V The voltage difference is -1 2 V. Therefore, with the left ear In view of this, the output voltage seems to be positively and negatively swinging between -12V ~ + 12V (-VCC ~ + VCC). The same is true for the right earphone. As above, according to the third embodiment, four earphone output terminals are required. Lack of versatility, but compared with the second embodiment, it has the advantage of being able to obtain about twice the output power. Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs Although the reference voltage generating circuit 7 or the voltage-dividing resistors R11 and R12 are used to generate the intermediate voltage of the power supply voltage VCC, the present invention is not limited to this. That is, as long as the intermediate voltage can be generated, all It can also be applied. In the first and second embodiments described above, although the voltage supplied to the second signal line COM is set to a voltage that is exactly 1/2 of the analog power supply voltage VCC, strictly speaking, it is not 1/2. Yes, as long as it can obtain the desired amplitude voltage or more, it may be slightly offset from the GND side or the VCC side. The above-mentioned third to third embodiments have three-dimensional sound corresponding to L and R channels. The earphones are described, but the corresponding earphones and the like are also applicable to the Chinese national standard (CNS) A4 specifications (210X 297 mm) -17- 541783 A7 B7 in the same paper size. 5. Description of the invention (1 order can be adapted to the present invention.乂 'Although the above embodiment uses the left and right earphones 1 2, i 3 as an example, it can also be applied to earphones with only one sound output section. (Please read the precautions on the back before filling this page) The first to third embodiments are suitable for portable electronic devices that are particularly expected to be small, lightweight, etc., but needless to say, they can also be applied to stand-alone electronic devices. In addition, each embodiment described above is merely an example of implementation of the present invention, and it should not be construed to limit the technical scope of the present invention. That is, the present invention can be implemented in various forms without departing from its spirit or its main features. According to the present invention, the consumer cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs printed the detailed description above. According to the present invention, the intermediate voltage of the power supply voltage is applied to the second signal line. / 2) ~ (+ power supply voltage / 2) are moved by positive and negative swing. Thereby, although no DC-cut capacitor is provided on the first signal line to which the sound signal is supplied, the output voltage to the sound output section can be made to swing positively and negatively. Therefore, it is possible to omit a very large capacitor which is conventionally required for outputting low-frequency sound, and to reduce the size, weight, and cost of electronic equipment. In addition, according to another feature of the present invention, since the intermediate signal of the reference signal is generated by the arithmetic amplifier, the impedance of the second signal line can be viewed from the sound output section and can be ignored and reduced. Furthermore, it is possible to suppress the voltage variation of the second signal line and maintain its potential at an intermediate voltage. Therefore, when the present invention is applied to stereo sound with two channels of L and R, the separation of the left and right channels and the S / N can be maintained at the same time, and the paper size of the left and right earphones can be adapted to the Chinese National Standard (CNS). A4 specifications (210X297 mm) -18- 541783 A7 ______ ______ B7_ 5. Description of the invention (The output voltage accurately swings between positive and negative. [Industrial Applicability] The present invention is a device that can It is very useful to make the output voltage of the headphone swing positive and negative, so as to try to reduce the size, weight and cost of electronic equipment. (Please read the precautions on the back before filling this page) Make a piece of paper A Ns c One quasi-one standard one ~ national one in China | suitable
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