200917903 九、發明說明： 【發明所屬之技術領域】 本發明係關於一種使複數個冷陰極放電燈（CCFL : Cold Cathode Fluorescent Lamp)、外部電極螢光燈或螢光燈等之 放電燈點燈之放電燈點燈裝置，且特別關於改善放電燈之 亮度梯度之技術。 【先前技術】 冷陰極放電燈’一般係利用變流器，用數l〇kHz之頻 率且施加數百V〜千數百V之電壓來進行點燈。又，亦有稱 為外部電極螢光燈（EEFL : External Electrode Fluorescent Lamp)之螢光官。外部電極螢光燈與冷陰極放電燈之電極構 造不同，除此以外幾乎相同，發光原理亦與冷陰極放電燈 相同。因此，用來使外部電極螢光燈或冷陰極放電燈點燈 之變流器的原理係相同。因&，以下，使用冷陰極放電燈 (簡稱放電燈）說明變流器。 圖1係表示此種變流器之構成圖。此變流器10係由交 流電壓產生電路丨丨與電壓轉換電路12構成。 流電 後從 交流電壓產生電路η係用既定頻率切換直流電源vin 流^電壓而產生夺泊雷懕。带麻、& μ & .—..... 。電壓轉換電路12係將來自交200917903 IX. Description of the Invention: [Technical Field] The present invention relates to a discharge lamp for a plurality of cold cathode fluorescent lamps (CCFLs), external electrode fluorescent lamps or fluorescent lamps. A discharge lamp lighting device, and in particular a technique for improving the brightness gradient of a discharge lamp. [Prior Art] A cold cathode discharge lamp 'generally uses a current transformer to perform lighting with a frequency of several 〇 kHz and a voltage of several hundred V to several hundreds of V. Also, there is a fluorescent officer called an external electrode fluorescent lamp (EEFL: External Electrode Fluorescent Lamp). The electrode structure of the external electrode fluorescent lamp is different from that of the cold cathode discharge lamp, except that it is almost the same, and the principle of light emission is the same as that of the cold cathode discharge lamp. Therefore, the principle of the converter for lighting the external electrode fluorescent lamp or the cold cathode discharge lamp is the same. For &, the converter is described below using a cold cathode discharge lamp (abbreviated as a discharge lamp). Fig. 1 is a view showing the configuration of such a current transformer. This converter 10 is composed of an AC voltage generating circuit 丨丨 and a voltage converting circuit 12. After the current is discharged, the AC voltage generating circuit η switches the DC power source vin current with a predetermined frequency to generate a bouncing thunder. With hemp, & μ & .-..... The voltage conversion circuit 12 will come from
器等具有正阻抗特性之元件串聯 性’因此將電容器或電 於放電燈，以使該合成 200917903 阻抗成為正阻抗特性。此時所連接之電容器稱為鎮流電容 器（ballast condenser)，線圈稱為鎮流線圈。圖2係表示透 過鎮流電容器C1〜C4,將放電燈i連接於變流器1〇之習知 放電燈點燈裝置之構成圖。 又，由於放電燈之長度越長點燈所需之電壓越高，因 此必須使變流器產生高電壓。其結果，必須使用大对壓之 零件，構成變流器，有變流器價格變高的問題。為解決此 種問題’開發了圖3所示之能使用小耐壓零件之變流器i〇a 之放電燈點燈裝置。 此放電燈點燈裝置係在構成變流器1〇a之電壓轉換電 路⑶之變Μ II Ta之二次繞組之中點設置中分接頭，將二 次繞組分割成二次繞組81(第！繞組）與二次繞組叫第2繞 ’:)，將中分接頭連接於接地(例如f體等)。放電燈點燈裝 =之構成係將二次繞組S1之-端（非接地端子）連接於第】 :==鎮流?容器C1〜C4,將第1輪出端子連接 連接於第2於屮之I將一次繞組S2之—端(非接地端子) 接於弟2輸出端子，透過鎮流電容器c5〜c8， 出端子連接於放電燈la〜ld之另—端。 ， ' 構：中’變η ^係將從二次繞組S1輸出之交 輪出至鎮流電容器C1，，將從二次繞 出之广電壓V3輸出至鎮流電容器C5〜c8。交流 相對父流電麗V2係反相。根據此構成，變壓器丁 _ * 繞組SI、S2只要產生變流器輸出 ：-次 使料壓小之變磨器。此外，轉換二了電，即可，能 吳電路12a有時亦用輸 200917903 出反相電壓之2個變壓器構成。 在使放電燈點燈之放電燈點燈裝置中，一般在放電燈 與構裝放電燈之筐體等之間存在寄生電容，通過該寄生電 容流出漏電流。放電燈越長所施加之電壓越高，漏電流亦 增大，其影響不容忽視。放電燈之亮度主要係由流經放電 燈之電流值來決定。流經放電燈之電流係原來之放電電流 與流經寄生電容之漏電流之合計。 圖4(b)係圖3所示之放電燈點燈裝置之漏電流分布 圖。圖4(b)中’與虛線所示之寄生電容平行描畫之箭頭係 表示流經各寄生電容之電流，箭頭之長度係表示流經電流 之大小。放電燈動作上之接地電位（GND電位）係在放電燈 之中心附近，漏電流之大小在放電燈之中心附近之兩側係 對稱。 圖5係表示流經放電燈之電流狀態，圖5(a)係表示電流 朝單向流動之情形，圖5(b)係表示電流朝反向流動之情形。 攸放電燈之管面通過寄生電容流向接地電位之漏電流亦有 助於放電燈之亮度。圖5中之箭頭數係模仿電流量，在放 電燈兩端之電流量較中心附近為多且兩端相等。因此，放 電燈之亮度係如圖4(a)所示，雖在放電燈之兩端變高且在中 心附近變低，但輝度梯度變小。 如上所述，圖3所示之習知放電燈點燈裝置，在放電 燈兩端無亮度差，又，由於放電燈之中心附近與兩端間之 輝度梯度小，實用上大多無問題，因此一般被廣為使用。 專利文獻1 :日本特開平8 — 122776號公報 200917903 【發明内容】 然而，上述圖3所示之習知放電燈點燈裝置中，對應】 個放電燈’必須要有2個鎮流電容器。特別在大型液晶電 視等所使用之放電燈數亦不少，例如，在使用2〇個放電燈 之液晶電視中，必須要有4〇個鎮流電容器。 此處，能考慮刪除串聯於圖3所示之放電燈點燈裝置 之各放電燈之2個電容器中之1個，具有如圖6所示之構 成之放電燈點燈裝置。 1,. 當二次繞組S1之_N2與二次繞組S2之ϋ數奶相 同時，從二次繞組81輸出之交_ V2之電麼值之絕對 值係與從二次繞組S2輸出之交流㈣v3之電録之絕對 值相等。此時，放電燈la〜ld之兩端對接地之電位相異。 。由於在鎮流電容器C1〜C4中產生壓降，因此連接鎮流電容 益CM〜C4之放電燈la〜ld之電極处附近對接地之電位變 低，其他之電極Ea附近的電位變高。 圖7⑻係表示圖6所示之放電燈點燈裝置之漏電流分 布圖。由於放電燈之電極附近對接地之電位相異，因此來 自未連接鎮流電容器〜U之電極附近之漏電流量較來自 另一電極附近之漏電流量為多。圖8係表示流經圖6所示 之放電燈點燈裝置之放電燈之電流狀態，圖8⑷係表示電流 朝單向流動之情形，圖8(b)係表示電流朝反向流動之情形。 由於放電燈兩端附近之電流值不同，因此如圖7⑷所示，放 電燈兩端之亮度亦相異。亦即’放電燈產生亮度梯度。此 200917903 亮度梯度在放電燈越長時越明顯。 在圖6所示之放電燈點燈裝置中，雖放電燈產生亮度 梯度，但有能刪除鎮流電容器之優點。因此，圖6所示之 放電燈點燈裝置，雖可適用於能容許某程度亮度梯度之用 途’但不適用於液晶電視或照明裝置等，人直接觀看的系 統或人能直接觀看的系統之用途。 本發明之課題在於提供一種即使減少零件數亦能減少 放電燈之亮度梯度之廉價的放電燈點燈裝置。 為解決上述課題，第丨發明之放電燈點燈裝置，其具 備.變流器，輸入直流電壓，轉換為以接地為基準電位之 第1交流電壓’及以該接地為該基準電位、相對該第i交 流電壓電壓相位為反相且電壓值小之第2交流電壓·;從第i 輸出端子輸出該第1交流電壓，從第 一"广 攸弟2輸出端子輸出該第2 壓；鎮流元件，一端連接於㈣1輸出端子；以及 =燈，連接於該鎮流元件之另—端與該帛2輸出端子之 第2發明係在第1發明 哭且供一 Κ敌電燈點燈裝置中，該變流 -具備.父流電壓產生電路， 产兩廢.u έ 係輸Α該直流電壓以產生交 々丨匕电堡，以及變壓器，具有一次 h 诘鈿及m /、—-人繞組，該一次 —且係用以輸入該交流電壓產生電路 厭，斥產生之該父流電 .土 —— 人邊組係由第1繞組鱼第：> 姑。冰 組之-端連接…… 繞組構成’該第1繞 鳊運接於5亥弟1輸出端子， 產生以該接地為該基準電位之第j六 於該接地， 之-端連接於該接地，另 1第2繞組 運接於該第2輪出端子，產 200917903 生以該接地為該基準電位、相對該第丄交流電壓電壓相位 為反相且電壓值小之該第2交流電壓。 第3發明係在第丨發明之放電燈點燈裝置中，該變流 器具備：交流電壓產生電路，係輸入該直流電壓以產生交 /’’《電壓’第1變壓器，具有用以輸入該交流電壓產生電路 所產生之交流電壓之一次繞組，及一端連接於該第丨輸出 端子、另一端連接於該接地、產生以該接地為該基準電位 之该第1交流電壓之二次繞組；以及第2變壓器，具有用 ( 以輸入該交流電壓產生電路所產生之該交流電壓之一次繞 組，及一端連接於該接地、另一端連接於該第2輸出端子、 產生以該接地為該基準電位、相對該第1交流電壓電壓相 位為反相且電壓值小之該第2交流電壓之二次繞組。 第4發明係在第1發明之放電燈點燈裝置中，該鎮流 元件係由電容器或線圈構成。 【實施方式】 ί， 以下’參照圖式詳細說明本發明之實施形態。 實施例1 圖9係表示本發明實施例丨之放電燈點燈裝置之構成 圖。該放電燈點燈裝置具備直流電源Vin、變流器10b、鎮 流電容器C1- C4、及放電燈la〜ld。該放電燈點燈裝置之構 成’除構成變流器1 Ob所包含之電壓轉換電路12b之變壓 器Tb之二次繞組si(第1繞組）之匝數N2與二次繞組S2(第 2繞組）之匝數N3之關係外，與圖6所示之習知放電燈點燈 200917903 裝置之構成相同。 圖6所示之習知放電燈點燈裝置中’如上所述，由於 來自放電燈la〜Id兩端之漏電流量相異’因此產生亮度梯 度。其原因在於來自放電燈la〜id兩端之接地之電位值之 絕對值相異。 又’把絕對值當作問題之理由如下。亦即’一般而言， 由於點燈中之放電燈能看作電阻，因此變流器（電壓轉換電 路12b)之負載係電阻與電容器之串聯電路。在此串聯電路 f 中，由於施加於電阻與電容器之各電壓相位不同，因此來 自電阻兩端之接地之電位之相位不同。但是，由於漏電流 量與相位無關，因此僅絕對值成為問題。 即使僅在放電燈la〜Id之一側加入鎮流電容器 C1~C4’若來自放電燈ia〜id兩端之接地之電位的絕對值相 等’則能減小亮度梯度。實施例1之放電燈點燈裝置係藉 由調整變壓器Tb之二次繞組S 1之匝數N2與二次繞組S2 之匝數N3 ’以使來自放電燈la〜id兩端之接地之電位之值 i? 的絕對值相等。 實施例1之放電燈點燈裝置與圖6所示之習知放電燈 點燈裝置之相異點係變壓器Tb之匝數比，換言之，係變壓 器Tb之輸出電壓。具體而言，變壓器Tb之二次繞組S1之 區數N2係設定成較二次繞組S2之區數N3為大。纟士果， 二次繞組S1所產生之交流電壓V2(第1交流電壓）之電壓值 較二次繞組S2所產生之交流電壓V3(第2交流電壓）之電壓 值為大。二次繞組S1之阻數N2係考慮鎮流電容器匸卜以 11 200917903 之壓降量而設定’以使二次繞組s 1產生預先加上此壓降量 之電壓。 在以上般構成之放電燈點燈裝置中，變壓器Tb係從第 1輸出端子輸出以接地為基準電位之交流電壓V2’從第2 輸出端子輸出以接地為基準電位、相對交流電壓V2電壓相 位為反相且電壓值小之交流電壓V3 ^藉此，能進行控制使 得放電燈1 a〜1 d兩端電位之絕對值相等。 根據以上所說明之本發明實施例丨之放電燈點燈裝 置，由於變壓器Tb之二次繞組S1之匝數N2能設定成較二 次繞組S2之阻數N3為大，藉由提高鎮流電容器C1〜C4側 之乂机電C V2，以使來自放電燈丨a〜丨d兩端之接地之電位 之值的絕對值相等，因此放電燈u〜ld兩端之漏電流值趨 近相等值’能減小亮度梯度。 實施例2 圖10係表示本發明實施例2之放電燈點燈裝置之構成 圖。此放電燈點燈裝置係將實施你"之放電燈點燈裝置之 變流器⑽變更為變流器…。更詳言之，係將變流器10b 所包含之電壓轉換電路12b變更為電壓轉換電&…。以 下，僅說明與實施例1相異之部分。 心、電：轉換電路⑶係由第1變壓器T1與第2變壓器T2 Ν λ、1相11 T1係由11數N1之-次繞組P1與數 =二二次繞組Si構成。第2變壓器T2係由随N3之一 人、、>〇，.且P2與匝數N4之-士镇細 之—-人繞組S2構成。第1變壓器T1 之一次繞組ΪΜ與第2變愚哭^ ^ 弟變壓Τ2之一次繞組Ρ2係並聯且連 12 200917903 接於交流電壓產生電路丨丨之輸出端子。第i變壓器丁丨之 二次繞組si之另一端（終繞端）與第2變壓器T2之二次繞組 S2之一端（始繞端（鲁側））係共通連接於接地。 第1變壓器Τ1之匝數比Ν2/Ν1係設定成較第2變壓器 Τ2之阻數比Ν4/Ν3為大，換言之’產生於第i變壓器η 之一次繞組S 1之交流電壓V2之電壓值係設定成較產生於 第2變壓器T2之二次繞組S2之交流電壓V3之電壓值為 大。此時，第i變壓器T1之二次繞組S1之&數比n2/ni 之設定係考慮鎮流電容器Cl〜C4之壓降量’以使二次繞組 S1產生預先加上此壓降量之電壓。 根據以上所說明之本發明實施例2之放電燈點燈裝 置，第1變壓器T1之匝數比N2/N1係設定成較第2變壓器 T2之匝數比N4/N3為大，使鎮流電容器C1〜C4側之交流電 壓V2之電壓值的絕對值大於交流電壓V3之電壓值的絕對 值，以使來自放電燈la〜Id兩端之接地之電位之值的絕對 值相等。因此，放電燈la〜ld兩端之漏電流值趨近相等值， 能減小亮度梯度。 實施例2之放電燈點燈裝置中，由於能進行實際動作 之驗證，因此將其結果表示如下。圖丨丨係表示為與實施例 2之放電燈點燈裝置比較，用習知放電燈點燈裝置所測量之 數值例=第1變壓器τι之匝數比N2/N1及第2變壓器T2 之匝數比Ν4/Ν3為10係相等。來自此時之放電燈1&〜1{1兩 端之接地之電位之值的絕對值係920Vrms(電壓有效值）與 lOOOVrms，有 80Vrms 的差。 13 200917903 圖12係表示本發明實施例2之放電燈點燈裝置所測量 之數值例。第1變壓器T1之匝數比N2/N1係12.5，第2變 壓器丁2之阻數比N4/N3係1〇。此時，來自放電燈 兩端之接地之電位之值的絕對值兩端皆能達到1。 亦即，以接地為基準電位，能使施加於放電燈之一端之電 壓值的絕對值與施加於另一端之電壓值的絕對值相等。藉 此’亮度梯度不會變差且能削減電容器之使用數。 曰 上又，在實施例丨、實施例2中，雖設置複數個放電燈， 但該放電燈數亦可為單燈（1燈）。 、根據第1發明，由於從連接鎮流元件之第丨輸出端子 輸出之第1交流電壓的絕對值係較從未連接鎮流元件之第2 輸出端子輸出之第2交流電壓的絕對值為大，因此即使鎮 僅連接於放電燈之—㈣，亦能使放電燈兩端之電 口此，此減小將鎮流元件僅連接於放電燈之一側 壳度梯度。又’由於能減少鎮流元件數，因此能 廉偏構成放電燈點燈裝置。 之第1 因此能 據第2發明，由於變流器係由具有匝數不同 繞組與第·^ & 1 、、堯、，·且所構成之二次繞組之變壓器構成， ν的零件數構成放電燈點燈裝置。 由於變流器係由匝數比不同之2個變 2變壓器）構成，因此能用廉價的零件 根據第3發明， 壓器（笫！ _ t V罘1變壓器及第 構成。 外部電極螢光燈或 一本發明可適用於使冷陰極放電燈 光燈等之放電燈點燈的裝置。 14 200917903 【圖式簡單說明】 圖1係表示習知放電燈點燈裝置所使用之變流器之構 成的圖。 圖2係表示習知放電燈點燈裝置之構成的圖。 圖3係表示習知其他放電燈點燈裝置之構成的圖。 圖4(a)、（b)係表示圖3所示之放電燈點燈裝置之漏電 流及亮度分布的圖。 圖5 (a)、（b)係表示圖3所示之放電燈點燈裝置中，流 經放電燈之電流狀態的圖。 圖6係表示從習知其他放電燈點燈裝置刪除部分電容 器時之構成的圖。 圖7(a)、（b)係表示圖6所示之放電燈點燈裝置之漏電 流及亮度分布的圖。 圖8〇)、（b)係表示圖6所示之放電燈點燈裝置中，流 經放電燈之電流狀態的圖。 圖9係表示本發明實施例1之放電燈點燈裝置之構成 的圖。 圖1 〇係表示本發明實施例2之放電燈點燈裝置之構成 的圖。 圖1】係表示為與本發明實施例2之放電燈點燈裝置比 較’用習知放電燈點燈裝置所測量之數值例的圖。 圖12係表示本發明實施例2之放電燈點燈裝置中所測 量之數值例的圖。 15 200917903 【主要元件符號說明】 la、 lb、 1 c、 Id 放 電 燈 10、 10a 、10b 、10c 變 流 器 11 交 流 電壓 產 生電路 12、 12a 、12b 、12c 電 壓 轉換 電 路 Cl、 C2 、C3、 C4 鎮 流 電容 器 C5、 C6 、C7、 C8 鎮流 電容 器 Ea、 Eb 電 極 P、PI、 P2 一 _ 次 繞組 SI 二 次 繞組 S2 二 次 繞組 T1 第 1 變壓 器 T2 第 2 變壓 器 Ta、 Tb 變 壓 器 Yin 直 流 電源 16The device is connected in series with a positive impedance characteristic, so that the capacitor or the electric discharge lamp is used to make the synthesized 200917903 impedance a positive impedance characteristic. The capacitor connected at this time is called a ballast condenser, and the coil is called a ballast coil. Fig. 2 is a view showing the configuration of a conventional discharge lamp lighting device which connects the discharge lamp i to the current transformer 1 through the ballast capacitors C1 to C4. Further, since the length of the discharge lamp is longer, the voltage required for lighting is higher, so that it is necessary to cause the converter to generate a high voltage. As a result, it is necessary to use a large-pressure part to constitute a current transformer, and there is a problem that the price of the converter becomes high. In order to solve such a problem, a discharge lamp lighting device capable of using a small-voltage-resistant component converter i〇a shown in Fig. 3 was developed. The discharge lamp lighting device is provided with a tap in a secondary winding of the secondary winding constituting the voltage conversion circuit (3) of the current transformer 1A, and divides the secondary winding into a secondary winding 81 (the first! The winding) and the secondary winding are called the second winding ':), and the middle tap is connected to the ground (for example, the f body, etc.). Discharge lamp lighting installation = the connection of the secondary winding S1 end (non-grounding terminal) to the first]: == ballast? Container C1 ~ C4, the first round of the terminal connection is connected to the second I connects the end of the primary winding S2 (non-grounding terminal) to the output terminal of the second terminal, through the ballast capacitors c5 to c8, and the output terminal is connected to the other end of the discharge lamps la to ld. The 'structure: medium' variable η ^ is output from the output of the secondary winding S1 to the ballast capacitor C1, and is output from the second-out wide voltage V3 to the ballast capacitors C5 to c8. The exchange is reversed relative to the parent flow of the V2 system. According to this configuration, the transformer _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ In addition, the conversion of the second power, that is, the Wu circuit 12a sometimes also uses the two transformers that output the reverse voltage of 200917903. In a discharge lamp lighting device for lighting a discharge lamp, a parasitic capacitance is generally present between the discharge lamp and a casing for constituting the discharge lamp, and a leakage current flows through the parasitic capacitance. The longer the discharge lamp is applied, the higher the voltage applied, and the leakage current also increases, and its influence cannot be ignored. The brightness of the discharge lamp is mainly determined by the current flowing through the discharge lamp. The current flowing through the discharge lamp is the sum of the original discharge current and the leakage current flowing through the parasitic capacitance. Fig. 4 (b) is a diagram showing the leakage current distribution of the discharge lamp lighting device shown in Fig. 3. The arrow drawn in parallel with the parasitic capacitance indicated by the broken line in Fig. 4(b) indicates the current flowing through each parasitic capacitance, and the length of the arrow indicates the magnitude of the current flowing. The ground potential (GND potential) at the discharge lamp operation is near the center of the discharge lamp, and the magnitude of the leakage current is symmetrical on both sides near the center of the discharge lamp. Fig. 5 is a view showing a state of current flowing through the discharge lamp, Fig. 5(a) shows a case where current flows in one direction, and Fig. 5(b) shows a case where current flows in a reverse direction. The leakage current of the tube surface of the discharge lamp through the parasitic capacitance to the ground potential also contributes to the brightness of the discharge lamp. The number of arrows in Fig. 5 simulates the amount of current, and the amount of current at both ends of the discharge lamp is more than that near the center and the ends are equal. Therefore, the brightness of the discharge lamp is as shown in Fig. 4(a), and the luminance gradient becomes small as it becomes higher at both ends of the discharge lamp and becomes lower near the center. As described above, the conventional discharge lamp lighting device shown in FIG. 3 has no brightness difference at both ends of the discharge lamp, and since the luminance gradient between the center and the both ends of the discharge lamp is small, practically, there is no problem. Generally used widely. However, in the conventional discharge lamp lighting device shown in Fig. 3, two ballast capacitors are required for the corresponding discharge lamps. In particular, the number of discharge lamps used in large-sized liquid crystal televisions is also large. For example, in a liquid crystal television using two discharge lamps, it is necessary to have four ballast capacitors. Here, it is conceivable to delete one of the two capacitors of the respective discharge lamps connected in series to the discharge lamp lighting device shown in Fig. 3, and to have a discharge lamp lighting device constructed as shown in Fig. 6. 1. When the _N2 of the secondary winding S1 is the same as the number of turns of the secondary winding S2, the absolute value of the value of the _V2 from the output of the secondary winding 81 is the same as the output of the output from the secondary winding S2. (4) The absolute value of the electricity record of v3 is equal. At this time, the ends of the discharge lamps la to ld are different from the ground potential. . Since a voltage drop occurs in the ballast capacitors C1 to C4, the potential of the ground is lowered near the electrode of the discharge lamps la to ld connected to the ballast capacitors CM to C4, and the potential near the other electrodes Ea becomes high. Fig. 7 (8) is a view showing a leakage current distribution of the discharge lamp lighting device shown in Fig. 6. Since the potential of the ground near the electrode of the discharge lamp is different, the amount of leakage current from the vicinity of the electrode to which the ballast capacitor is not connected is higher than the amount of leakage current from the vicinity of the other electrode. Fig. 8 is a view showing a state of current flowing through a discharge lamp of the discharge lamp lighting device shown in Fig. 6. Fig. 8(4) shows a case where current flows in one direction, and Fig. 8(b) shows a case where current flows in a reverse direction. Since the current values near the two ends of the discharge lamp are different, the brightness of the two ends of the discharge lamp is also different as shown in Fig. 7 (4). That is, the 'discharge lamp produces a brightness gradient. This 200917903 brightness gradient is more pronounced as the discharge lamp is longer. In the discharge lamp lighting device shown in Fig. 6, although the discharge lamp produces a luminance gradient, there is an advantage that the ballast capacitor can be removed. Therefore, the discharge lamp lighting device shown in FIG. 6 can be applied to a device that can tolerate a certain degree of brightness gradient, but is not suitable for a liquid crystal television or a lighting device, etc., a system directly viewed by a person or a system that can be directly viewed by a person. use. An object of the present invention is to provide an inexpensive discharge lamp lighting device which can reduce the brightness gradient of a discharge lamp even if the number of parts is reduced. In order to solve the above problems, a discharge lamp lighting device according to a third aspect of the invention includes a current transformer that inputs a DC voltage, converts it into a first AC voltage ' with a ground potential as a reference potential, and uses the ground as the reference potential. The second alternating voltage of the ith AC voltage and voltage phase is inverted and the voltage value is small; the first alternating current voltage is output from the ith output terminal, and the second voltage is output from the first "Guangzhao 2 output terminal; a flow element having one end connected to the (four) 1 output terminal; and a = lamp connected to the other end of the ballast element and the second invention of the 帛2 output terminal in the first invention crying and being supplied to an enemy lamp lighting device , the converter - has a parent flow voltage generating circuit, produces two wastes. The system generates the DC voltage to generate the AC power, and the transformer has a primary h 诘钿 and m /, - human winding This time - and is used to input the AC voltage generating circuit, and the parental current generated by the repelling. The human side group is composed of the first winding fish: > The end connection of the ice group... The winding constitutes 'the first winding is connected to the 5th output terminal of the 5th, and the ground is the jth of the reference potential at the ground, and the end is connected to the ground, The other second winding is transported to the second round-out terminal, and the second alternating current voltage having a low voltage phase is opposite to the phase of the second alternating current voltage with the ground potential being the reference potential. According to a third aspect of the invention, in the discharge lamp lighting device of the invention, the converter includes: an alternating current voltage generating circuit that inputs the direct current voltage to generate a first voltage transformer, which has a a primary winding of an alternating current voltage generated by the alternating voltage generating circuit, and a secondary winding having one end connected to the second output terminal and the other end connected to the ground to generate the first alternating current voltage at which the ground is the reference potential; The second transformer has a primary winding for inputting the alternating current voltage generated by the alternating current voltage generating circuit, and one end is connected to the ground and the other end is connected to the second output terminal, and the ground is used as the reference potential. In the discharge lamp lighting device according to the first aspect of the invention, the ballast element is a capacitor or [Embodiment] Embodiments of the present invention will be described in detail below with reference to the drawings. Embodiment 1 FIG. 9 is a view showing a discharge lamp dot of an embodiment of the present invention. The discharge lamp lighting device includes a DC power source Vin, a current transformer 10b, a ballast capacitor C1-C4, and discharge lamps 1a to 1d. The discharge lamp lighting device is configured to "construct the converter 1" The relationship between the number of turns N2 of the secondary winding si (first winding) of the transformer Tb of the voltage conversion circuit 12b included in Ob and the number of turns N3 of the secondary winding S2 (second winding) is the same as that shown in FIG. The discharge lamp lighting 200917903 has the same configuration. In the conventional discharge lamp lighting device shown in Fig. 6, as described above, since the amount of leakage current from both ends of the discharge lamps 1a to 1d is different, a brightness gradient is generated. The reason is that the absolute values of the ground potentials from the ground ends of the discharge lamps la~id are different. The reason for using the absolute value as a problem is as follows. That is, in general, the discharge lamp in the lighting can be regarded as a resistor, and thus a load circuit of the current transformer (voltage conversion circuit 12b) is a series circuit of a capacitor. In this series circuit f, since the phases of the voltages applied to the resistor and the capacitor are different, the potential from the ground at both ends of the resistor Different phases However, since the amount of leakage current is independent of the phase, only the absolute value becomes a problem. Even if only one side of the discharge lamps 1a to 1d is added to the ballast capacitors C1 to C4', the ground potential from both ends of the discharge lamp ia~id The absolute value is equal to 'the brightness gradient can be reduced. The discharge lamp lighting device of the first embodiment adjusts the number N2 of the secondary winding S 1 of the transformer Tb and the number N3 of the secondary winding S2 to cause the discharge from The absolute value of the value of the ground potential of the two ends of the lamps la to id is equal. The difference between the discharge lamp lighting device of the first embodiment and the conventional discharge lamp lighting device shown in Fig. 6 is the transformer Tb. The ratio, in other words, the output voltage of the transformer Tb. Specifically, the number of regions N2 of the secondary winding S1 of the transformer Tb is set to be larger than the number N3 of the secondary winding S2. In the gentleman's fruit, the voltage value of the AC voltage V2 (the first AC voltage) generated by the secondary winding S1 is larger than the voltage of the AC voltage V3 (the second AC voltage) generated by the secondary winding S2. The resistance number N2 of the secondary winding S1 is set in consideration of the ballast capacitor by the voltage drop amount of 11 200917903 to cause the secondary winding s 1 to generate a voltage to which the voltage drop amount is applied in advance. In the discharge lamp lighting device configured as described above, the transformer Tb outputs an AC voltage V2' whose grounding is the reference potential from the first output terminal, and outputs the ground potential as a reference potential from the second output terminal, and the voltage phase is relative to the AC voltage V2. The AC voltage V3, which is inverted and has a small voltage value, can be controlled so that the absolute values of the potentials across the discharge lamps 1a to 1d are equal. According to the discharge lamp lighting device of the embodiment of the invention described above, since the number of turns N2 of the secondary winding S1 of the transformer Tb can be set to be larger than the resistance number N3 of the secondary winding S2, by increasing the ballast capacitor The electromechanical C V2 on the C1 to C4 side is such that the absolute values of the potentials from the grounds of the discharge lamps 丨a to 丨d are equal, so that the leakage current values at both ends of the discharge lamps u to ld approach an equal value. 'Can reduce the brightness gradient. (Embodiment 2) Fig. 10 is a view showing the configuration of a discharge lamp lighting device according to a second embodiment of the present invention. This discharge lamp lighting device changes the converter (10) that implements your discharge lamp lighting device to a current transformer. More specifically, the voltage conversion circuit 12b included in the converter 10b is changed to voltage conversion power & Hereinafter, only the portion different from the embodiment 1 will be described. Heart and Electricity: The conversion circuit (3) is composed of a first transformer T1 and a second transformer T2 Ν λ, and a phase 11 T1 is composed of an 11-number N1 primary winding P1 and a number = secondary winding Si. The second transformer T2 is composed of a human winding S2 which is one of N3, >, and P2 and the number of turns N4. The primary winding 第 of the first transformer T1 and the second variable 愚 哭 ^ ^ ^ ^ ^ ^ ^ ^ 一次 一次 之 之 之 之 2009 2009 2009 2009 2009 2009 2009 2009 2009 2009 2009 2009 2009 2009 2009 2009 2009 2009 2009 2009 2009 2009 2009 2009 2009 2009 2009 2009 The other end (final winding end) of the secondary winding si of the i-th transformer is connected to the ground of one end (the starting end (lu-side)) of the secondary winding S2 of the second transformer T2. The turns ratio Ν2/Ν1 of the first transformer Τ1 is set to be larger than the resistance ratio Ν4/Ν3 of the second transformer Τ2, in other words, the voltage value of the alternating current voltage V2 generated in the primary winding S1 of the i-th transformer η The voltage value of the AC voltage V3 set to be smaller than the secondary winding S2 of the second transformer T2 is set to be large. At this time, the &numerical ratio n2/ni of the secondary winding S1 of the i-th transformer T1 is set in consideration of the voltage drop amount of the ballast capacitors C1 to C4 so that the secondary winding S1 is pre-applied with this voltage drop amount. Voltage. According to the discharge lamp lighting device of the second embodiment of the present invention described above, the turns ratio N2/N1 of the first transformer T1 is set to be larger than the turns ratio N4/N3 of the second transformer T2, so that the ballast capacitor is made larger. The absolute value of the voltage value of the AC voltage V2 on the C1 to C4 side is larger than the absolute value of the voltage value of the AC voltage V3 so that the absolute values of the potentials from the grounds at both ends of the discharge lamps 1a to 1d are equal. Therefore, the leakage current values at both ends of the discharge lamps la to ld approach an equal value, and the luminance gradient can be reduced. In the discharge lamp lighting device of the second embodiment, since the actual operation can be verified, the results are shown below. The figure is shown as a numerical example measured by a conventional discharge lamp lighting device as compared with the discharge lamp lighting device of the second embodiment = the first transformer τ1 turns ratio N2/N1 and the second transformer T2 The number Ν4/Ν3 is equal to 10 systems. The absolute value of the value of the ground potential from both ends of the discharge lamp 1&~1{1 at this time is 920 Vrms (voltage rms) and 100 rmrms, which is 80 Vrms. 13 200917903 Fig. 12 is a view showing an example of numerical values measured by the discharge lamp lighting device of the second embodiment of the present invention. The turns ratio of the first transformer T1 is 12.5 for the N2/N1 system, and the resistance ratio of the second transformer T2 is 1〇 for the N4/N3 system. At this time, the absolute value of the potential from the ground at both ends of the discharge lamp can reach 1 at both ends. That is, with the ground as the reference potential, the absolute value of the voltage value applied to one end of the discharge lamp can be made equal to the absolute value of the voltage value applied to the other end. By this, the brightness gradient does not deteriorate and the number of capacitors can be reduced. Further, in the second embodiment and the second embodiment, a plurality of discharge lamps are provided, but the number of the discharge lamps may be a single lamp (one lamp). According to the first aspect of the invention, the absolute value of the first alternating current voltage outputted from the second output terminal connected to the ballast element is larger than the absolute value of the second alternating current voltage outputted from the second output terminal of the unconnected ballast element. Therefore, even if the town is only connected to the discharge lamp (4), the electric port at both ends of the discharge lamp can be made, which reduces the ballast element to be connected to only one side of the discharge lamp. Further, since the number of ballast elements can be reduced, the discharge lamp lighting device can be constructed inexpensively. First, according to the second aspect of the invention, the converter is composed of a transformer having a plurality of windings and a secondary winding formed by the first and second windings, and the number of parts of ν is constituted. Discharge lamp lighting device. Since the converter is composed of two transformers with different turns ratios, it is possible to use inexpensive parts according to the third invention, and the transformer (笫! _ t V罘1 transformer and the first component. External electrode fluorescent lamp) Or a device which can be applied to lighting a discharge lamp such as a cold cathode discharge lamp, etc. 14 200917903 [Simplified description of the drawings] Fig. 1 shows a configuration of a converter used in a conventional discharge lamp lighting device. Fig. 2 is a view showing a configuration of a conventional discharge lamp lighting device. Fig. 3 is a view showing a configuration of another conventional discharge lamp lighting device. Fig. 4 (a) and (b) are views showing Fig. 4; Fig. 5 (a) and (b) are diagrams showing the state of current flowing through the discharge lamp in the discharge lamp lighting device shown in Fig. 3. Fig. 6 is a view showing a state of current flowing through the discharge lamp. Fig. 7(a) and Fig. 7(b) are diagrams showing leakage current and luminance distribution of the discharge lamp lighting device shown in Fig. 6. Figs. 7(a) and 7(b) are diagrams showing the configuration of a conventional capacitor lamp lighting device. 8A) and (b) show the electricity flowing through the discharge lamp in the discharge lamp lighting device shown in Fig. 6. A diagram of the flow state. Fig. 9 is a view showing the configuration of a discharge lamp lighting device according to a first embodiment of the present invention. Fig. 1 is a view showing the configuration of a discharge lamp lighting device according to a second embodiment of the present invention. Fig. 1 is a view showing an example of numerical values measured by a conventional discharge lamp lighting device in comparison with the discharge lamp lighting device of the second embodiment of the present invention. Fig. 12 is a view showing an example of numerical values measured in the discharge lamp lighting device of the second embodiment of the present invention. 15 200917903 [Description of main components] la, lb, 1 c, Id Discharge lamps 10, 10a, 10b, 10c Converter 11 AC voltage generation circuits 12, 12a, 12b, 12c Voltage conversion circuits Cl, C2, C3, C4 Ballast capacitors C5, C6, C7, C8 Ballast capacitors Ea, Eb Electrodes P, PI, P2 _ secondary winding SI secondary winding S2 secondary winding T1 1st transformer T2 2nd transformer Ta, Tb Transformer Yin DC power supply 16