201001387 九、發明說明： 【發明所屬之技術領域】 本發明係關於一種液晶顯不益及其驅動方法。 【先前技術】 因爲液晶顯示器（Liquid Crystal Display，LCD)具有體 積較小’耗電較低以及輻射小等優點，所以得到廣泛之應 用。 目前之液晶顯示器一般包括一液晶顯示面板及一背光 驅動電路。因爲液晶顯示面板不能主動發光，所以需要該 月光驅動電路爲該液晶顯示面板提供光線。該液晶顯示写 外表面般5又置按鍵，該液晶顯示器之用戶可以通過操作 該按鍵來控制該背光驅動電路提供之光線強度，從而調節 該液晶顯示面板顯示之圖像亮度。 如果液晶顯示器之用戶在看電影時，或者液晶顯示器 周圍環境光比較暗時，用戶需要手動去設定該液晶顯示器 面板之亮度。而且，用戶設定完成後，該背光驅動電路提 供之光線強度不能自動變化。 、如果用戶爲該背光驅動電路所提供之光線設定了一個 強度’而該液晶顯示面板實際顯示之圖像不需要很 :二首但是用戶忘記去重新設定背光亮度，此時會造成 5亥液日日顯示器之能源浪費。 圖像：外^該液晶顯示器需要顯示較暗之圖像或者黑色 ::夺二由於該背光驅動電路只能提供用 光線，常常導致钤、为B扣_ 度之 μ /日日頌不器顯示之圖像之亮度往往較 201001387 大’不能獲得較好之視覺效果。 【發明内容】 之液晶201001387 IX. INSTRUCTIONS: TECHNICAL FIELD OF THE INVENTION The present invention relates to a liquid crystal display and a driving method thereof. [Prior Art] Since a liquid crystal display (LCD) has a small volume, low power consumption, and low radiation, it is widely used. Currently, liquid crystal displays generally include a liquid crystal display panel and a backlight driving circuit. Since the liquid crystal display panel cannot actively emit light, the moonlight driving circuit is required to provide light to the liquid crystal display panel. The liquid crystal display writes an outer surface like a button, and the user of the liquid crystal display can control the light intensity provided by the backlight driving circuit by operating the button, thereby adjusting the brightness of the image displayed by the liquid crystal display panel. If the user of the LCD monitor is watching a movie, or when the ambient light around the LCD monitor is dark, the user needs to manually set the brightness of the LCD panel. Moreover, the light intensity provided by the backlight driving circuit cannot be automatically changed after the user setting is completed. If the user sets an intensity for the light provided by the backlight driving circuit, and the actual display image of the liquid crystal display panel does not need to be very: two but the user forgets to reset the brightness of the backlight, which will cause 5 Hai liquid days. The energy of the daily display is wasted. Image: External ^The LCD monitor needs to display a darker image or black:: Di 2 Because the backlight drive circuit can only provide light, it often leads to B, _ degree μ / day 颂 器 display The brightness of the image is often larger than 201001387 'can not get a better visual effect. SUMMARY OF THE INVENTION
有鐘於此’提供一種能夠自動調整背光強声 示器實為必要。 提供一種上述液晶顯示器之驅動方法亦實為必要。 -種液晶顯示器’其包括一背光驅動電路，該背光驅 動電路包括-控制單sm及—負載。該控制單元 用於根據外部之圖像訊號提供一第一控制訊號及一第二栌 制訊號至該逆變器。該逆變器用於根據該第一控制訊號^ 該第二控制訊號來調整該負載之發光強度。 一種液晶顯示器，其包括一背光驅動電路，該背光驅 動電路包括一控制單元、一調整單元、一逆變器及一負載。 該控制單元用於根據外部之圖像訊號提供一第一控制訊號 至該逆變器，並根據外部之圖像訊號提供一第二控制訊號 至該調整單元。該調整單元用於根據該第二控制訊號提供 一調整電壓至該逆變器。該逆變器用於根據該第一控制訊 號及該調整電壓輸出一調整電流至該負載，該調整電流可 以調整該負載之發光強度。 一種液晶顯示器’其包括一控制單元，一逆變器及一 負載’該控制單元能夠接收外部之圖像訊號並根據圖像訊 號提供至少一控制訊號至該逆變器，該逆變器用於根據該 控制说號調整該負载之工作電流。 一種液晶顯示器’其包括一控制單元，一逆變器及一 負載’該控制單元用於根據外部之圖像訊號提供多個第一 201001387 控制訊號及多個第二控制訊號至該逆變器，該逆變器用於 根據該多個第一控制訊號及該多個第二控制訊號調整該負 載之工作電流。 一種液晶顯示器驅動方法’該液晶顯示器包括包括一 控制單元、一逆變器及一負載，該方法包括接收圖像訊號； 計算所接收之圖像訊號對應之圖像亮度值；根據圖像亮度 值提供一第一控制訊號及一第二控制訊號；根據該第一控 制訊號及該第二控制訊號調整該負載之發光強度。 相較於先前技術，上述液晶顯示器包括該控制單元及 該逆變器’該控制單元根據接收之圖像訊號輸出該至少一 控制訊號至該逆變器，該逆變器根據該至少一控制訊號自 動調整該負載之發光強度。上述液晶顯示器驅動方法可以 根據對接收之圖像訊號之計算結果來調整該負載之發光強 度。 【實施方式】 請參閱圖1，是本發明液晶顯示器（未標示）第一實 鈀方式之電路方框示意圖。該液晶顯示器包括一液晶顯示 面板（圖未示）及一背光驅動電路1〇。該背光驅動電路1〇 用來爲該液晶顯示面板提供光線，該液晶顯示面板用來根 據外部之圖像訊號顯示對應圖像。 s亥背光驅動電路10包括一控制單元11、一逆變器13 及一負載14。該控制單元u用於根據外部之圖像訊號提 供一第一控制訊號及一第二控制訊號至該逆變器13。該逆 變益13用於分別根據該第一、第二控制訊號調整該負載 201001387 2之工作電流。該負載14在不同之I作電流下具有不同 :光強度。該第-、第二控制訊號爲脈衝訊號，均具有一It is necessary to provide a strong sounder that can automatically adjust the backlight. It is also necessary to provide a driving method of the above liquid crystal display. A liquid crystal display 'which includes a backlight driving circuit including - control single sm and - load. The control unit is configured to provide a first control signal and a second control signal to the inverter according to the external image signal. The inverter is configured to adjust the luminous intensity of the load according to the first control signal. A liquid crystal display comprising a backlight driving circuit, the backlight driving circuit comprising a control unit, an adjusting unit, an inverter and a load. The control unit is configured to provide a first control signal to the inverter according to the external image signal, and provide a second control signal to the adjusting unit according to the external image signal. The adjusting unit is configured to provide an adjustment voltage to the inverter according to the second control signal. The inverter is configured to output an adjustment current to the load according to the first control signal and the adjustment voltage, and the adjustment current can adjust an illumination intensity of the load. A liquid crystal display includes a control unit, an inverter and a load. The control unit is capable of receiving an external image signal and providing at least one control signal to the inverter according to the image signal, the inverter being used according to the The control number adjusts the operating current of the load. A liquid crystal display includes a control unit, an inverter and a load. The control unit is configured to provide a plurality of first 201001387 control signals and a plurality of second control signals to the inverter according to an external image signal. The inverter is configured to adjust an operating current of the load according to the plurality of first control signals and the plurality of second control signals. A liquid crystal display driving method includes: a control unit, an inverter, and a load, the method comprising: receiving an image signal; calculating an image brightness value corresponding to the received image signal; and determining an image brightness value according to the image Providing a first control signal and a second control signal; adjusting the luminous intensity of the load according to the first control signal and the second control signal. Compared with the prior art, the liquid crystal display includes the control unit and the inverter. The control unit outputs the at least one control signal to the inverter according to the received image signal, and the inverter is configured according to the at least one control signal. The luminous intensity of the load is automatically adjusted. The above liquid crystal display driving method can adjust the luminous intensity of the load based on the calculation result of the received image signal. [Embodiment] Please refer to Fig. 1, which is a block diagram of a circuit of a first real palladium mode of a liquid crystal display (not shown) of the present invention. The liquid crystal display comprises a liquid crystal display panel (not shown) and a backlight driving circuit 1A. The backlight driving circuit 1 is configured to provide light to the liquid crystal display panel, and the liquid crystal display panel is configured to display a corresponding image according to an external image signal. The backlight circuit 10 includes a control unit 11, an inverter 13, and a load 14. The control unit u is configured to provide a first control signal and a second control signal to the inverter 13 according to an external image signal. The inverse benefit 13 is used to adjust the operating current of the load 201001387 2 according to the first and second control signals, respectively. The load 14 has a different current at different I: light intensity. The first and second control signals are pulse signals, each having a
定之占空比。所謂占空比，轴Η邮I ^ ^ ^ . ,疋脈衝矾旒之一個周期内訊 唬之持、，、貝時間及整個周期之持續時間之比值。 該背光驅動電路1Q正常工作時，該控制單元u接收 外部之圖像訊號’並對所接收之s像訊號進行計算。 控制ΐ該，11接收對應黑色圖像之圖像訊號前，該 工J早7L 11輸ώ之該第一控制訊號之纟空比大小取決於 用戶對圖像顯示亮度之需求設^。該第-控制訊號之占空 比之範圍可以是在〇〜100%。比如，用戶可以通過 3控制單元11之外部⑽（°η — display)單元調節 该第一控制訊號之占空比，該外部之0SD單元可以包括延 伸至該液晶顯示II之外表面之按鍵以方便用戶操作控制。 同時，該控制單元1 i輸出之該第二控制訊號具 空比。 β ώ ，該控制單元11接收對應黑色圖像之圖像訊號時，該 控制單元11根據對所接收之圖像訊號之計算結果輸出具 有對應占空比之該第一控制訊號。該計算結果可以代表所 接收之圖像訊號對應之圖像之平均亮度值。該計算結果與 該第一控制訊號之占空比大小具有一預先設定之線性或者 非線性對應關係，如：該計算結果可以爲0〜100，其中0 代表最暗（此時圖像訊號對應之黑色圖像），100代表最亮 (此時圖像訊號對應全白圖像），對應之該第一控制訊號之 占空比爲20%〜100%。上述對圖像訊號之計算過程可以由 201001387 一預先设置在該控制單元n之計算電路實現，比如，該計 算電路可以預先存儲多個不同之圖像訊號與其對應之亮度 值之關係。每當接收一幅圖像所包括之全部或者部份圖像 σ孔號夺就對接收之圖像訊號進行計算，從而得到對應之 該幅圖像之亮度值。同時，該控制單元1:輸出具有一第二 占二比之第一控制訊號，並且該第二控制訊號此後將保持 具有該第二占空比。其中，該第二控制訊號之第一占空比 大於其第二占空比。如該第一占空比可以爲100%，該第二 占空比可以爲20%。因此，當該控制單元u接收對應黑 圖像之圖像訊號後，該第二控制訊號之占空比由該^一占 空比變爲該第二占空比。在該背光驅動電 過程中’該第二控制訊號將保持該第二占空比。後之 該逆變器13接收該第一控制訊號及該第二控制訊 號，並輸出一調整電流至該負載14。該第一控制訊號用來 調整該調整電流之占空比，而該第二控制訊號用來調整該 調整電流之幅值。該調整電流大小同時正比於該第一、第 二控制訊號之占空比。該第-、第：控制訊號之占空比之 二者中任意一個單獨減小，該調整電流都會減小。當該第 一控制訊號之占空比及該調整電壓同時減小時，該=電 流減小。該調整電流之占空比及幅值分別決定該負載Μ ::作電流之占空比及幅值。所以’當該調整電流減小時， 该負載14之工作電流減小。 201001387 收之圖像訊號對應黑色圖像。如圖所示，自t〇時刻開如 該第一控制訊號之占空比減小，於是該調整電流之占空比 減^ _ ’該第二控制訊號之占空比由第—占空比減小 爲弟二占空比’對應之調整電壓由第一調整電壓減小爲第 二調整電壓，於是該調整電流之幅值也減小。 因此’該背光驅動電路10能夠根據接收之圖像訊號自 動調整該負冑14之發光強度，使該液晶顯示器在顯示黑色 圖像時之亮度較低，該液晶顯示器顯示圖像之效果較好。 請參閱圖3，是本發明液晶顯示器（未標示）第二實 施方式之電路方框示意圖。該液晶顯示器包括一液晶顯示 面板（圖未示）及一背光驅動電路2〇。該背光驅動電路2〇 用來爲該液晶顯示面板提供光線，該液晶顯示面板用來根 據外部之圖像訊號顯示對應圖像。 5玄煮光驅動電路20包括一控制單元21、一調整單元 22、一逆變器23及一負載24。該控制單元21用於根據外 部之圖像訊號提供一第一控制訊號至該逆變器23及一第 二控制訊號至該調整單元22。該液晶顯示面板接收該圖像 訊號並顯示具有具有對應亮度之圖像。該調整單元22用於 接收該第二控制訊號，並根據該第二控制訊號提供一調整 電壓至該逆變器23。該逆變器23用於接收該第一控制訊 號及該調整電壓，並根據該第一控制訊號及該調整電壓提 供一調整電流，該調整電流對應該負載24之工作電流。該 第一控制訊號用來調整該調整電流之占空比，該第二控制 訊號則用來調整該調整調整電流之幅值。該調整電壓爲一 11 201001387 直流電壓。該負載24用於爲該液晶顯示面板提供光線。該 負載之工作電流可以是一正弦波電流。其中，該第一及第 一控制訊號都是脈衝訊號，該第一及第二控制訊號均具有 一疋之占空比。該負載24可以是多個冷陰極管（cold cathode fluorescent lamp，CCFL)。該負載 24 可以設置在該 液晶顯示面板側邊，或者設置在該液晶顯示面板背面。 請參閱圖4，是圖3所示調整單元22之電路結構示意 圖。該調整單元22包括一積分電路（未標示）。該積分電 路包括一電阻221及一電容222，該電阻221串聯在該控 制單元21及該逆變器23之間，該電容222串聯在該電阻 221與該逆變器23之間一節點及地之間。該電阻221及該 電容222實際上構成一 r_C電路。該r_c電路可以將輸入 之脈衝訊號進行積分，並轉換成直流電壓輸出，而且該直 流電壓之大小與輸入之脈衝訊號之占空比成正比。也就是 說，如果輸入之脈衝訊號之占空比越小，則輸出之直流電 壓越小。該電阻之大小可以爲1 ΚΩ，該電容大小可以爲 47 ju F ° 該積分電路包括該電阻221及電容222構成之R_C電 路’因此該積分電路能夠將該控制單元21提供之第二控制 訊號轉換成該調整電壓。 該背光驅動電路20正常工作時，該控制單元21接收 外部之圖像訊號，並對所接收之圖像訊號進行計算。 在該控制單元21接收對應黑色圖像之圖像訊號前，該 控制單元21輸出之該第一控制訊號之占空比大小取決於 12 201001387 〇用二：圖像顯示亮度之需求設定’其範圍可以是在 〇比如，用戶可以通過一連接至該控制單元21之 2 OSD(⑽咖en display)單元調節該第—控制訊號之占 冰。卜#之〇SD單元可以包括延伸至該液晶顯示器之 之按鍵以方便用戶操作控制。同時，該控制單元^ 輸出之該第二控制訊號具有一第一占空比。 在該控制單元21接收對應一第一參考亮度值之圖像 2像訊料’該控鮮元^㈣對所接收之圖像訊號之 ^結果輸出具有對應占空比之該第—控制訊號。該計算 〜果可以代表所接收之圖像訊號對應之圖像之平均亮度 值=計算結果與該第一控制訊號之占空比大小具有一預 先設定之線性或者非線性對應關係，如：該計算結果可以 爲ι〇0 /、中〇代表最暗（此時圖像訊號對應黑色圖像）， 1〇〇代表最亮（此時圖像訊號對應白色圖像），對應之該第 控制訊號之占空比爲20%〜1〇〇%。上述對圖像訊號之計 算過程可以由一預先設置在該控制單元21之計算電路實 現，比如，該計算電路可以預先存儲多個不同之圖像訊號 與其對應之亮度值之關係。每當接收一幅圖像之指定部份 之圖像訊號，就對所接收之圖像訊號進行計算，從而得到 該幅圖像對應之亮度值。 同時，該控制單元21輸出之第二控制訊號具有一第二 占空比，其中，該第二控制訊號之第一占空比大於其第二 占空比。如該第一占空比可以冑1〇〇%，該帛二占空比可 以爲20%。此後，當該控制單元21接收對應一第二參考 13 201001387 亮度值之圖像訊號時 第一占空比。 β亥第一控制訊號之占空比還原至該 該第-參考亮度值對應之圖像亮度小於該第二參考齐 度值對應之圖像亮度。比如’該第—參考亮度值對應之圖 像可以爲黑色圖像，該第二參考亮度值對應之圖像可 白色圖像。另外’該第-參考亮度值及該第二參考亮度值 可以根據不同客戶之需要在出廠時進行設置。 因此’當該控制單元21接收對應該第_參考亮产值之 圖像之圖像訊號後，該第二控制訊號之占空比由一占 空比變爲該第二占空比，並根據該控制單元21接收之圖像 訊號對應之圖像亮度在該第一占空比及該第二占空比之間 切換。 如上所述’在該控制單元21接收對應該第一參考亮度 值之圖像之圖像訊號之前，該控制單元21輸出之第二控制 訊號具有该弟一占空比，並定義此時該調整單元22輸出之 調整電壓爲第一調整電壓。在該控制單元21接收對^該第 一參考亮度值之圖像之圖像訊號後，該控制單元21輸出之 第二控制訊號具有該第二占空比，並定義此時該調整單元 22輸出之調整電壓爲第二調整電壓。因爲該第一占空比大 於該第二占空比，所以該第一調整電壓大於該第二調整電 壓。比如，當該第一占空比爲100%，該第二占空比爲2〇% 時，該第一調整電壓可以爲2·1 V，該第二調整電壓可以爲 0.6V。 該逆變器23接收該第一控制訊號及該調整電壓，並根 201001387 據該第一控制訊號及該調整電壓輸出該調整電流至該負載 24。該調整電流大小同時正比於該第—控制訊號之占/空比 及該調整電壓之大小。該第-控制訊號之占空比及該調整 電壓二者中任意一個單獨減小，該調整電流都會減小。當 該第一控制訊號之占空比及該調整電壓同時減小時，該調 整電流減小。同時，該調整電流大小決定該負載％之工作 電流大小。當該調整電流減小時，該負載24之工作電流減 /J\ 〇 "月參閱圖5 ’是圖3所不之背光驅動電路2〇之調整電 流之波形變化示意圖。&中，在心夺刻該控制單元所接收 之圖像訊號對應黑色圖像。如圖所示，自刻開始，該 第一控制訊號之占空比減小，於是該調整電流之占空比減 t。同時，該第二控制訊號之占空比由第一占空比減小爲 第二占空比，對應之調整電壓由第—調整電壓減小爲第二 調整電壓，於是該調整電流之幅值減小。因此 色圖像時，該負載24之發光強声 日β 一 科 兀*涵度紅小，該液晶顯示面板顯 不之圖像之党度較低’該液晶顯示器顯示圖像之效果較 好在t2時刻，該控制單元21接收對應白色圖像之圖像 ^，該第-控制訊號之占空比增大，該第二控制訊號之 ^ ^ I舄这第—占空比，該調整電壓對 應由該第二調整電壓變爲該第一 [灼茨弟凋整電壓。於是，該調整 電Λ丨L之占空比及幅值對應增大。 上 9〇 & 八艳樣的活，該背光驅動電 ，可以在需要顯示黑色圖像時減小該負載24之發光強 度’而在顯示白色圖像時增大該負載24之發光強度。 15 201001387 事實上，该背光驅動電路20具有兩個工作狀態：接收 對應該第-參考亮度值之圖像之圖像訊號之前之工作狀態 及接收對應該第一參考亮度值之圖像之圖像訊號之後之工 作狀^。定義接收對應該第一參考亮度值之圖像之圖像訊 ，之前之工作狀態爲靜態工作狀態，接收對應該第一參考 冗度值之圖像之圖像訊號之後之工作狀態爲動態工作狀 態。 那麼，在靜態工作狀態時，該背光驅動電路2〇之負載 24之發光強度疋由該液晶顯示器之用戶設定之；在動態工 作狀態時，該背光驅動電路2〇之負載之發光強度是由^背 光驅動電路20進行自動調整的。該控制單元21可以根據 接收之圖像訊號調整該第一及第二控制訊號之輸出，從而 自動調整該負載24之發光強度，使得該液晶顯示面板在該 背光驅動電路10處於動態工作狀態時，顯示之對應該第一 參考亮度值之圖像之亮度降低且顯示之對應該第二^考亮 度值之圖像之亮度不降低。 綜上所述，在該背光驅動電路2〇處於動態工作狀態 時，該負載24之發光強度可以根據圖像訊號被自動調整二 從而使該液晶顯示面板可以獲得較好之顯示效果，較高之 對比度以及較好之省電性能。 门 請參閱圖6，是本發明液晶顯示器（未標示）第三實 施方式之電路方框示意圖。該液晶顯示器包括一液晶顯示 面板（圖未示）及一背光驅動電路3〇。該背光驅動電^路 包括一控制單元31、一調整單元32、一逆變器幻及一負 16 201001387 載34。該控制單元31包括一復位電路311。 該控制單元31用於根據外部之圖像訊號提供一第一 控制訊號至該逆變器33及一第二控制訊號至該調整單元 32。該調整單元32用於接收該第二控制訊號，並根據該第 二控制訊號提供一調整電壓至該逆變器33。該逆變器33 用於接收該第一控制訊號及該調整電壓，並根據該第一控 制讯號及該調整電壓提供一調整電流用來調節該負載34 之工作電流。 該調整電壓爲一直流電壓。該負載34用於爲該液晶顯 示面板k供光線。該調整電流可以是一正弦波電流。其中， 該第一及第二控制訊號都是脈衝訊號，該第一及第二控制 訊號均具有一定之占空比，且該第一、第二控制訊號之幅 值爲3.3V。該負載34可以是多個冷陰極管（c〇ld cath〇de fluorescent lamp，CCFL)。該負載34可以設置在該液晶顯 示面板側邊，或者設置在該液晶顯示面板背面。 請參閱圖7，是圖6所示調整單元32之電路結構示意 圖。該調整單元32包括一積分電路36及一分壓電路37。 該積分電路36包括一第一電阻361、一第二電阻362、一 第一電容363及一第二電容364，該第一及第二電阻361、 362依次串聯在該控制單元31及該逆變器33之間，該第 一及第二電容363、364並聯在該第一電阻361及該第二電 阻362之間一節點及地之間。該第一電阻361及該第一、 第二電容363、364實際上構成一 R_c電路。該分壓電路 37包括一第三電阻371、一第四電阻372及一第三電容 17 201001387 373。該第三、第四電阻371、372依次串接在一 5V直流 電壓源及地之間。該第三、第四電阻371、372之間一節^ 連接至該逆變器33，即該直流電壓源經由該第三電阻 連接至該逆變器33，該直流電壓源還經由該第三電阻37ΐ 及該第三電容373接地。該積分電路％用於將該第二控制 訊號轉換成一直流電壓，該分壓電路37用於將該積分電路 36轉換得到之直流電壓進行分壓處理得到該調整電壓。 該背光驅動電路30正常工作時，該控制單元31接收外部 之圖像訊號，並對所接收之圖像訊號進行計算。 在該控制單元31接收之圖像訊號對應黑色圖像前，該 第一控制單元輸出之該第一控制訊號之占空比取決於用戶 對圖像顯示亮度之需求設^，該第—控制訊號之占空比之 範圍可以是0〜100%。此時，該控制單元21輸出一具有第 一占空比之該第二控制訊號。 在該控制單兀31接收之圖像訊號對應黑色圖像時，該 控制單元31根據對所接收之圖像訊號之計算結果輸出具 有對應占空比之該第一控制訊號。該計算結果可以代表所 接收之圖像訊號對應之圖像之亮度參考值。該計算結果與 «亥第控制吼號之占空比大小具有一預先設定之線性或者 非線性對應關係，如：該計算結果可以爲〇〜1〇〇，其中〇 代表最暗（此時圖像訊號對應之黑色圖像），1〇〇代表最亮 (此時圖像訊號對應全白圖像），對應之該第一控制訊號之 占空比爲20%〜100%。上述對圖像訊號之計算過程可以由 一預先設置在該控制單元21之計算電路實現，比如，該計 18 201001387 算電路可以預先存儲多個圖像訊號與對應之亮度值之關 係’每當接收一幅圖像之指定部份之圖像訊號，就對接收 之圖像訊號進行计舁，從而得到該幅圖像之平均亮度值。 同^•該控制單元31輸出之該第二控制訊號具有__第三占 空比。其中，該第一占空比大於該第二占空比，如該第一 以爲聰，該第二占空比可以爲2〇%。在該控制 Γ Γ办1妾收對應黑色圖像之圖像訊號後，該第二控制訊號 二比根據所接收之圖像訊號對應之圖像亮度在該第一 占空比及該第二占空比之間變化。也就是說，該控單元31 輸出具有對應圖像亮度之占Μ之第_控制訊號，且此時 之占空比在該第一占空比及該第二占空比之間。 因：，當：控制單元31接收之圖像訊號對應黑色圖像 該第-、第二控制訊號之占空比由該控制單元31根據 接收之圖像訊號對應之圖像之亮度值自動控制。 =復位電路311包括一延伸至該液晶顯示面板外表面之控 二根據用戶需求重定該第_、第二控制訊號： Μ弟一、第一控制訊號返回至該控制單元未接收對應里 色圖像之圖像訊號時之輸出。即，該液晶顯示 以通過對該復位電路311之控制使該第一控制訊號返回至 =有用戶歧之占空比，同時使該第：控制訊號返回至具 有第一占空比。 /、 如上所述，在該控制單元⑴妾收之圖像訊號對應里色 圖像前’該控制單元31輪出之第二控制訊號具有該第： 空比’定義此時該調整單元32輸出之調整電壓爲第一調整 19 201001387 電壓。在/玄控制單元31接收對應黑色圖像之圖像訊號時， 4控制單7L 31輸出之第二控制訊號具有該第二占空比，定 義此時該調整單元32輸出之調整電壓爲第二調整電壓。因 爲該第:占空比大於該第二占空比，所以該第一調整電壓 〇於該第二調整電壓。比如，當該第-占空比爲100%，該 一占二比爲2〇%時，該第一調整電壓可以爲2.1V，該第 二調整電壓可以爲〇.6V。 二該逆變器33接收該第一控制訊號及該調整電壓，並根 據忒第_控制訊號及該調整電壓分別調整該調整電流之占 空比及幅值M吏該調整電流之占空比及幅值分別減小。該 凋王，々丨L大小同時正比於該第一控制訊號之占空比及該調 整電壓之大小。因此，該第一控制訊號之占空比及該調整 電壓一者中任意一個單獨減小，該調整電流都會減小。當 忒第一控制訊號之占空比及該調整電壓同時減小時，該調 整電流減小。同時，該調整電流大小決定該負載之工作電 流大小。當該調整電流減小時，該負載之工作電流減小。 該調整電流與該第一、第二控制訊號之關係可以爲：1 = 314 X VxD τ 1.414 (其中’I代表調整電流，v代表調整電壓， D代表該第一控制訊號之占空比）。 因此在該液晶顯示器顯示黑色圖像時，該背光驅動電 路30提供之背光強度較小。而在黑色圖像顯示過後，該背 光驅動電路30可以自動之根據圖像訊號調整該第一及第 二控制訊號之占空比，進而調整該逆變器33輸出之調整電 流之占空比及幅值，使該負載34在顯示黑色圖像時發光強 20 201001387 ’該負载34之發光 色圖像之亮度不會 度較小，而且在此後之圖像顯示過程中 強度根據圖像訊號自動調整，顯示之白 降低。 鬥之it說，該調整電流之占空比不能低於正常工作範 一 比如，占空比不低於20% )，該調整電流之 幅值也不能低於其正作範圍之最小值（如W)，否 則該液晶顯示器顯示之圖像之效果會受至影響，甚至顯干 之圖: 象會出現水波紋等現象。因此，通過單獨調整占= 或者早獨調整幅值來調整負載發光強度之液晶顯示器在顯 不黑色圖像之時候其亮度無法得到進—步降低，導致其對 比度只能達至ό000 · 1 -h -4- I » , 一 ^ 1左右。比如，一般之液晶顯示器顯 不白色圖像時最大亮度爲則流明，顯示黑色圖像時之亮 度爲0.05流日月’則其對比度爲_〇 : 1。另外，在圖像訊 號對應之圖像亮度-致之情況下，該負載34之發光強度不 同也會導致該液晶顯示器顯示之圖像之亮度不同。通過單 獨調整占空比或者單獨調整幅值來調整負載發光強度之液 晶顯示器在顯示白色圖像時其最大亮度及最小亮度之間之 π度可變化範圍通常較小，比如顯示白色圖像之最大亮度 爲300流明，顯示白色圖像最小亮度爲67流明，其亮度調 整範圍僅爲（300— 67) + 300= 75%。 在該液晶顯示器顯示黑色圖像時，該第一控制訊號可 以控制该调整電流之占空比至正常工作範圍之最小值，該 第二控制訊號可以控制該調整電流之幅值至正常工作範圍 之最小值，因此能夠同時對該調整電流之占空比及幅值進 21 201001387 灯:周正口亥調整電流之大小可以變化至比單獨調整該調整 f流之占空比或者幅值之情況下更小，從而使該液晶顯示 益顯不之黑色圖像之亮度更低。通過該背光驅動電路30 對㈣整電流之占空比及幅值之㈣調整，該液晶顯示器 之：比ί可：顯著提高。比如，該液晶顯示器顯示白色圖 像¥之最大冗度可以爲珊流明，顯示黑色圖像時之亮度 可以低至0.014流明左右，從而對比度可達至2〇_:工以 上’使該液晶顯示器顯示之圖像具有良好之視覺效果。該 液晶顯示器顯示白色圖像之最大亮度可以爲300流明，顯 不白色圖像之最小亮度可以爲12流明，其亮度調整範圍可 以大大提高，達至（3〇〇—12) + 3〇〇=96%。 在匕該背光驅動電路3〇接收對應黑色圖像之圖像訊號 4該月光驅動電路3〇根據接收之圖像訊號對應之圖像亮 度自動調整該調整電流’從而調整該負載％之發光強度。 因此’該液晶顯示器顯示可以獲得較好之顯示效果，較高 之對比度效果以及較好之省電性能。 本，明並不限於以上實施方式，如：第一實施方式中 之^制單兀11在接受至對應黑色圖像之圖像訊號時，該控 制早70 11輸出之該第一控制訊號保持與用戶設定之亮度 值對應之占工比’该第二控制訊號之占空比變爲該第二 空比。 …另外，第一實施方式中之第二控制訊號可以爲直流電 ，。孔號。在該控制單A u接收對應黑色圖像之圖像訊號 刚’ 5亥第—控制訊號之電壓大小爲—第—電壓，在該控制 22 201001387 單元11接收對應黑色圖像之圖像訊號後，該第二控制訊號 之電壓大小變爲一第二電壓，且該第一電壓大於第二電 壓。該第一電壓可以是2.1V，該第二電壓可以是〇.6v。 另外，第三實施方式中之調整單元32可以被省略。當 該背光驅動電路30處於靜態工作狀態時，該控制單元31 輸出至該逆變器33之該第二控制訊號是一 21V直流電 壓，而當該背光驅動電路處於動態工作狀態時，該控制單 元31輸出至該逆變器33之該第二控制訊號是一 〇 6v直流 電壓。上述工作過程可以通過該控制單元21内部之軟體或 者硬體設置實現。 另外，第二實施方式中之復位電路311可以與一 〇sd 單元結合，用戶可以通過調節〇SD單元之内容使該第一控 制訊號及該第二控制訊號重定。 1外，第三實施方式中之復位電路311可以設置在該 控制單元31之外，並通過該控制單元31重定該第一、 二控制訊號。 另外，第三實施方式中之控制單元31可以更改設定啓 動該背光驅動電4 30動態工作模式之條件，即可以 收對應特定亮度值之时之圖像訊料 = 30進入動態工作模式。 牙祕動電路 另外，第二實施方式中之控制單元21輸出之第二 «在該背光驅動電路2G處於動“作狀態時會自 據接收之圖像訊號對應之圖像亮度值進行調整，該㈣電 壓也對應變化。如’該第二控制訊號在該控制單元21接收 23 201001387 之圖像訊號對應之圖像亮度值變化時，其占空比對應不同 之圖像亮度值在該第-占空比及該第二占空比之間自動變 化。該第二控制訊號之占空比之變化可以由該控制單元u 之軟體或者硬體設置實現，這種變化可以是線性之或者是 非線性之，也可以是連續之或者是非連續的。 另外’第二實施方式中之控制單元21輸出之該第二控 制訊號之占空比在靜態工作狀態時及動態工作狀態時可以 保持不變。該第二控制訊號在靜態工作狀態時具有一第一 頻率，在動態工作狀態時具有一第二頻率，該第一頻率大 於該第二頻率。該第一頻率對應該第一調整電壓，該第二 頻率對應該第二調整電壓。 另外’第二實施方式中之控制單元21可以輸出多個第 一控制訊號及多個第二控制訊號，該多個第— 於調整該調整電流之占空比，該多個第二控制訊 整該調整電流之幅值。 另外，第二實施方式中之控制單元21可以輸出至少一 控制訊號，從靜態工作狀態進入動態工作狀態時，該至少 一控制訊號之占空比及頻率分別變小，從而該調整電流之 占空比及頻率分別變小。 另外，第二實施方式中之控制單元21可以輸出至少一 控制訊號，在從靜態工作狀態進入動態工作狀態時，^至 少一控制訊號之占空比及幅值分別變小，從而該調整電流 之占空比及幅值分別變小。 & 另外，第二實施方式中之控制單元21還可提供一第三 24 201001387 =制訊號至該逆變器23。該第三控制訊號在靜態工作狀態 時之頻率大於其在動態工作狀態時之頻率，從而使該調整 電流在靜態玉作狀態時之頻率也大於其在動態工作狀態時 之頻率。 綜上所述，本發明確已符合發明專利之要件，爰依法 提出專射請。惟，以域述者僅為本發明之較佳實施方 ^，本發明之·並不以上述實施方式為限，舉凡熟悉本 案技藝之人士援依本發明之精神所作之等效修飾或變化， 皆應涵蓋於以下申請專利範圍内。 【圖式簡單說明】 圖1係本發明液晶顯示器第一實施方式電路方框示意 圖° 圖2係圖1所示背光驅動電路之調整電流波形變化示意 圖 〇 圖3係本發明液晶顯示器第二實施方式電路方框示意 圏 〇 ,V_k 圖4係圖3所示調整單元電路結構示意圖。 圖5係圖3所示背光驅動電路之調整電流波形變化示意 圖6係本發明液晶顯示器第三實施方式電路方框示意 圖7係圖6所示調整單元之電路結構示意圖。 【主要元件符號說明】 背光驅動電路10、20、30 第一電阻 25 201001387 控制單元 11 、 21 、 31 第二電阻 362 調整單元 22 ' 32 第三電阻 371 逆變器 13 、 23 、 33 第四電阻 372 負載 14 、 24 、 34 第一電容 363 電阻 221 第二電容 364 電容 222 第三電容 373 26The duty cycle is fixed. The so-called duty cycle, the axis Η I I ^ ^ ^ . , 疋 矾旒 矾旒 矾旒 矾旒 矾旒 一个 一个 一个 一个 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 When the backlight driving circuit 1Q is operating normally, the control unit u receives the external image signal ' and calculates the received s image signal. Controlling, 11 before the image signal corresponding to the black image is received, the blank ratio of the first control signal transmitted by the JJ 7L 11 depends on the user's requirement for the brightness of the image display. The duty ratio of the first control signal can be in the range of 〇~100%. For example, the user can adjust the duty ratio of the first control signal through the external (10) (° η - display) unit of the control unit 11, and the external OFDM unit can include a button extending to the outer surface of the liquid crystal display II for convenience. User operation control. At the same time, the second control signal outputted by the control unit 1 i has a null ratio. When the control unit 11 receives the image signal corresponding to the black image, the control unit 11 outputs the first control signal having the corresponding duty ratio according to the calculation result of the received image signal. The result of the calculation can represent the average brightness value of the image corresponding to the received image signal. The calculation result has a preset linear or non-linear correspondence relationship with the duty ratio of the first control signal, for example, the calculation result may be 0 to 100, where 0 represents the darkest (in this case, the image signal corresponds to Black image), 100 represents the brightest (in this case, the image signal corresponds to the all-white image), and the duty ratio of the first control signal is 20%~100%. The calculation process of the image signal may be implemented by a calculation circuit preset in the control unit n in 201001387. For example, the calculation circuit may pre-store a relationship between a plurality of different image signals and their corresponding brightness values. Whenever all or part of the image included in an image is received, the received image signal is calculated to obtain the brightness value of the corresponding image. At the same time, the control unit 1: outputs a first control signal having a second ratio, and the second control signal will thereafter maintain the second duty ratio. The first duty cycle of the second control signal is greater than the second duty cycle thereof. If the first duty cycle can be 100%, the second duty cycle can be 20%. Therefore, after the control unit u receives the image signal corresponding to the black image, the duty ratio of the second control signal is changed from the duty ratio to the second duty ratio. The second control signal will maintain the second duty cycle during the backlight drive process. The inverter 13 receives the first control signal and the second control signal, and outputs an adjustment current to the load 14. The first control signal is used to adjust the duty ratio of the adjustment current, and the second control signal is used to adjust the amplitude of the adjustment current. The magnitude of the adjustment current is also proportional to the duty cycle of the first and second control signals. Any one of the duty ratios of the first and third control signals is individually reduced, and the adjustment current is reduced. When the duty ratio of the first control signal and the adjustment voltage are simultaneously reduced, the = current is reduced. The duty cycle and amplitude of the adjustment current determine the duty cycle and amplitude of the load Μ :: current. Therefore, when the adjustment current is decreased, the operating current of the load 14 is reduced. 201001387 The received image signal corresponds to a black image. As shown in the figure, since the duty ratio of the first control signal is decreased from time t, the duty ratio of the adjustment current is decreased by _ 'the duty ratio of the second control signal is determined by the first duty ratio The adjustment voltage corresponding to the reduction of the duty ratio of the second is reduced from the first adjustment voltage to the second adjustment voltage, and the magnitude of the adjustment current is also reduced. Therefore, the backlight driving circuit 10 can automatically adjust the luminous intensity of the negative cymbal 14 according to the received image signal, so that the liquid crystal display has a low brightness when displaying a black image, and the liquid crystal display has a better effect of displaying an image. Referring to Figure 3, there is shown a block diagram of a second embodiment of a liquid crystal display (not shown) of the present invention. The liquid crystal display comprises a liquid crystal display panel (not shown) and a backlight driving circuit 2''. The backlight driving circuit 2 is configured to provide light to the liquid crystal display panel, and the liquid crystal display panel is configured to display a corresponding image according to an external image signal. The simmering light driving circuit 20 includes a control unit 21, an adjusting unit 22, an inverter 23, and a load 24. The control unit 21 is configured to provide a first control signal to the inverter 23 and a second control signal to the adjustment unit 22 according to the external image signal. The liquid crystal display panel receives the image signal and displays an image having a corresponding brightness. The adjusting unit 22 is configured to receive the second control signal, and provide an adjustment voltage to the inverter 23 according to the second control signal. The inverter 23 is configured to receive the first control signal and the adjustment voltage, and provide an adjustment current according to the first control signal and the adjustment voltage, and the adjustment current corresponds to an operating current of the load 24. The first control signal is used to adjust the duty ratio of the adjustment current, and the second control signal is used to adjust the amplitude of the adjustment current. The adjustment voltage is a 11 201001387 DC voltage. The load 24 is used to provide light to the liquid crystal display panel. The operating current of the load can be a sinusoidal current. The first and first control signals are pulse signals, and the first and second control signals each have a duty cycle of one turn. The load 24 can be a plurality of cold cathode fluorescent lamps (CCFLs). The load 24 may be disposed on the side of the liquid crystal display panel or on the back side of the liquid crystal display panel. Please refer to FIG. 4, which is a schematic diagram of the circuit structure of the adjusting unit 22 shown in FIG. The adjustment unit 22 includes an integration circuit (not shown). The integrating circuit includes a resistor 221 and a capacitor 222. The resistor 221 is connected in series between the control unit 21 and the inverter 23. The capacitor 222 is connected in series between the resistor 221 and the inverter 23. between. The resistor 221 and the capacitor 222 actually constitute an r_C circuit. The r_c circuit can integrate the input pulse signal and convert it into a DC voltage output, and the magnitude of the DC voltage is proportional to the duty ratio of the input pulse signal. That is, if the duty cycle of the input pulse signal is smaller, the DC voltage of the output is smaller. The size of the resistor may be 1 ΚΩ, and the capacitor may be 47 ju F °. The integrating circuit includes the resistor 221 and the capacitor 222 formed by the R_C circuit. Therefore, the integrating circuit can convert the second control signal provided by the control unit 21. Into this adjustment voltage. When the backlight driving circuit 20 is operating normally, the control unit 21 receives an external image signal and calculates the received image signal. Before the control unit 21 receives the image signal corresponding to the black image, the duty ratio of the first control signal output by the control unit 21 depends on 12 201001387. 2: Image display brightness requirement setting 'its range For example, the user can adjust the ice of the first control signal through an OSD ((10) coffee display unit) connected to the control unit 21. The SD unit may include a button extending to the liquid crystal display to facilitate user operation control. At the same time, the second control signal output by the control unit ^ has a first duty ratio. The control unit 21 receives the image 2 corresponding to a first reference brightness value, and the control unit outputs a first control signal having a corresponding duty ratio to the received image signal. The calculation may be representative of the average brightness value of the image corresponding to the received image signal = the calculation result has a predetermined linear or non-linear correspondence with the duty ratio of the first control signal, such as: The result can be ι〇0 /, the middle 〇 represents the darkest (the image signal corresponds to the black image), 1 〇〇 represents the brightest (the image signal corresponds to the white image), corresponding to the first control signal The duty ratio is 20%~1〇〇%. The calculation process of the image signal may be implemented by a calculation circuit preset in the control unit 21. For example, the calculation circuit may pre-store a relationship between a plurality of different image signals and their corresponding brightness values. Each time an image signal of a specified portion of an image is received, the received image signal is calculated to obtain a brightness value corresponding to the image. At the same time, the second control signal outputted by the control unit 21 has a second duty ratio, wherein the first duty ratio of the second control signal is greater than the second duty ratio thereof. If the first duty cycle is 胄1〇〇%, the second duty cycle can be 20%. Thereafter, when the control unit 21 receives an image signal corresponding to a second reference 13 201001387 luminance value, the first duty ratio. The duty ratio of the first control signal of the β-hai is restored until the image brightness corresponding to the first reference brightness value is smaller than the image brightness corresponding to the second reference uniformity value. For example, the image corresponding to the first reference brightness value may be a black image, and the image corresponding to the second reference brightness value may be a white image. In addition, the first reference brightness value and the second reference brightness value can be set at the factory according to the needs of different customers. Therefore, after the control unit 21 receives the image signal corresponding to the image of the _th reference lighting value, the duty ratio of the second control signal changes from a duty ratio to the second duty ratio, and according to the The image brightness corresponding to the image signal received by the control unit 21 is switched between the first duty ratio and the second duty ratio. As described above, before the control unit 21 receives the image signal corresponding to the image of the first reference luminance value, the second control signal output by the control unit 21 has the duty ratio and defines the adjustment at this time. The regulated voltage output by unit 22 is the first regulated voltage. After the control unit 21 receives the image signal of the image of the first reference brightness value, the second control signal output by the control unit 21 has the second duty ratio, and defines the output of the adjusting unit 22 at this time. The adjustment voltage is the second adjustment voltage. Because the first duty cycle is greater than the second duty cycle, the first adjustment voltage is greater than the second regulation voltage. For example, when the first duty ratio is 100% and the second duty ratio is 2〇%, the first adjustment voltage may be 2·1 V, and the second adjustment voltage may be 0.6V. The inverter 23 receives the first control signal and the adjustment voltage, and the root controller 201001387 outputs the adjustment current to the load 24 according to the first control signal and the adjustment voltage. The magnitude of the adjustment current is proportional to the ratio of the occupation/empty ratio of the first control signal and the adjustment voltage. The duty ratio of the first control signal and the adjustment voltage are individually reduced, and the adjustment current is reduced. When the duty ratio of the first control signal and the adjustment voltage are simultaneously reduced, the adjustment current is decreased. At the same time, the magnitude of the adjustment current determines the operating current of the load %. When the adjustment current is reduced, the operating current of the load 24 is reduced by /J\ 〇 " month see Fig. 5' is a waveform change diagram of the adjustment current of the backlight driving circuit 2〇 shown in Fig. 3. In &, the image signal received by the control unit is corresponding to the black image. As shown in the figure, the duty ratio of the first control signal is reduced from the moment of engraving, and the duty ratio of the adjustment current is decreased by t. At the same time, the duty ratio of the second control signal is reduced from the first duty ratio to the second duty ratio, and the corresponding adjustment voltage is reduced from the first adjustment voltage to the second adjustment voltage, so the amplitude of the adjustment current Reduced. Therefore, when the color image is used, the light of the load 24 is strong, the sound of the day β is a small degree, the density is small, and the image of the liquid crystal display panel is low. The effect of displaying the image on the liquid crystal display is better. At time t2, the control unit 21 receives the image corresponding to the white image, the duty ratio of the first control signal increases, and the second control signal has a first duty ratio, and the adjustment voltage corresponds to The second adjustment voltage is changed to the first [Zengzidian voltage. Therefore, the duty ratio and amplitude of the adjustment voltage L are correspondingly increased. The upper 9 〇 &; 艳 样 , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , 15 201001387 In fact, the backlight driving circuit 20 has two operating states: an operating state before receiving an image signal corresponding to an image of the first reference luminance value and an image of receiving an image corresponding to the first reference luminance value The work after the signal ^. Defining an image signal that receives an image corresponding to the first reference brightness value, the previous working state is a static working state, and the working state after receiving the image signal corresponding to the image of the first reference redundancy value is a dynamic working state . Then, in the static working state, the luminous intensity of the load 24 of the backlight driving circuit 2 is set by the user of the liquid crystal display; in the dynamic working state, the luminous intensity of the load of the backlight driving circuit 2 is determined by ^ The backlight drive circuit 20 performs automatic adjustment. The control unit 21 can adjust the output of the first and second control signals according to the received image signal, thereby automatically adjusting the illumination intensity of the load 24, so that the liquid crystal display panel is in a dynamic working state when the backlight driving circuit 10 is in a dynamic working state. The brightness of the image corresponding to the first reference brightness value displayed is lowered and the brightness of the image corresponding to the second brightness value is not lowered. In summary, when the backlight driving circuit 2 is in a dynamic working state, the luminous intensity of the load 24 can be automatically adjusted according to the image signal, so that the liquid crystal display panel can obtain a better display effect, which is higher. Contrast and better power saving performance. Gate Referring to Figure 6, there is shown a block diagram of a circuit of a third embodiment of the liquid crystal display (not shown) of the present invention. The liquid crystal display comprises a liquid crystal display panel (not shown) and a backlight driving circuit 3''. The backlight driving circuit includes a control unit 31, an adjusting unit 32, an inverter phantom and a negative 16 201001387 load 34. The control unit 31 includes a reset circuit 311. The control unit 31 is configured to provide a first control signal to the inverter 33 and a second control signal to the adjustment unit 32 according to an external image signal. The adjusting unit 32 is configured to receive the second control signal, and provide an adjustment voltage to the inverter 33 according to the second control signal. The inverter 33 is configured to receive the first control signal and the adjustment voltage, and provide an adjustment current according to the first control signal and the adjustment voltage for adjusting an operating current of the load 34. The adjustment voltage is a DC voltage. The load 34 is used to supply light to the liquid crystal display panel k. The adjustment current can be a sinusoidal current. The first and second control signals are all pulse signals, and the first and second control signals each have a certain duty ratio, and the amplitudes of the first and second control signals are 3.3V. The load 34 can be a plurality of cold cathode tubes (CCFLs). The load 34 may be disposed on the side of the liquid crystal display panel or on the back side of the liquid crystal display panel. Please refer to FIG. 7, which is a schematic diagram of the circuit structure of the adjusting unit 32 shown in FIG. The adjusting unit 32 includes an integrating circuit 36 and a voltage dividing circuit 37. The integrating circuit 36 includes a first resistor 361, a second resistor 362, a first capacitor 363 and a second capacitor 364. The first and second resistors 361 and 362 are sequentially connected in series to the control unit 31 and the inverter. The first and second capacitors 363 and 364 are connected in parallel between the node between the first resistor 361 and the second resistor 362 and the ground. The first resistor 361 and the first and second capacitors 363, 364 actually constitute an R_c circuit. The voltage dividing circuit 37 includes a third resistor 371, a fourth resistor 372, and a third capacitor 17 201001387 373. The third and fourth resistors 371, 372 are sequentially connected in series between a 5V DC voltage source and ground. The third and fourth resistors 371, 372 are connected to the inverter 33, that is, the DC voltage source is connected to the inverter 33 via the third resistor, and the DC voltage source is further connected via the third resistor 37ΐ and the third capacitor 373 are grounded. The integrating circuit % is used to convert the second control signal into a DC voltage, and the voltage dividing circuit 37 is configured to perform a voltage division process on the DC voltage converted by the integrating circuit 36 to obtain the adjusted voltage. When the backlight driving circuit 30 is operating normally, the control unit 31 receives an external image signal and calculates the received image signal. Before the image signal received by the control unit 31 corresponds to the black image, the duty ratio of the first control signal output by the first control unit depends on the user's requirement for the brightness of the image display, and the first control signal The duty cycle can range from 0 to 100%. At this time, the control unit 21 outputs the second control signal having the first duty ratio. When the image signal received by the control unit 31 corresponds to a black image, the control unit 31 outputs the first control signal having a corresponding duty ratio according to the calculation result of the received image signal. The result of the calculation can represent the brightness reference value of the image corresponding to the received image signal. The calculation result has a preset linear or nonlinear correspondence relationship with the duty ratio of the «Haidi control nickname, for example, the calculation result may be 〇~1〇〇, where 〇 represents the darkest (the image at this time) The black image corresponding to the signal), 1〇〇 represents the brightest (in this case, the image signal corresponds to the all-white image), and the duty ratio of the first control signal is 20%~100%. The calculation process of the image signal may be implemented by a calculation circuit preset in the control unit 21. For example, the circuit 18 201001387 may pre-store the relationship between the plurality of image signals and the corresponding brightness values. The image signal of a specified portion of an image is counted on the received image signal to obtain an average brightness value of the image. The second control signal outputted by the control unit 31 has a __third duty ratio. The first duty ratio is greater than the second duty ratio. For example, the first duty ratio is Cong, and the second duty ratio may be 2〇%. After the control unit receives the image signal corresponding to the black image, the second control signal 2 is greater than the image brightness corresponding to the received image signal at the first duty ratio and the second The air ratio changes. That is, the control unit 31 outputs a first control signal having a corresponding image brightness, and the duty ratio at this time is between the first duty ratio and the second duty ratio. Because: the image signal received by the control unit 31 corresponds to the black image. The duty ratio of the first and second control signals is automatically controlled by the control unit 31 according to the brightness value of the image corresponding to the received image signal. The reset circuit 311 includes a control unit extending to the outer surface of the liquid crystal display panel to re-determine the first and second control signals according to user requirements: Μ一一, the first control signal is returned to the control unit, and the corresponding color image is not received. The output of the image signal. That is, the liquid crystal display returns the first control signal to the duty ratio of the user by controlling the reset circuit 311 while returning the first control signal to have the first duty ratio. /, as described above, before the image signal received by the control unit (1) corresponds to the color image, the second control signal that the control unit 31 rotates has the first: empty ratio 'defined at this time, the adjustment unit 32 outputs The adjustment voltage is the first adjustment 19 201001387 voltage. When the image control signal corresponding to the black image is received by the control unit 31, the second control signal outputted by the control unit 7L 31 has the second duty ratio, and the adjustment voltage output by the adjustment unit 32 is defined as the second. Adjust the voltage. Because the first: the duty ratio is greater than the second duty ratio, the first adjustment voltage is greater than the second adjustment voltage. For example, when the first duty ratio is 100%, and the second ratio is 2〇%, the first adjustment voltage may be 2.1V, and the second adjustment voltage may be 〇.6V. The inverter 33 receives the first control signal and the adjustment voltage, and adjusts the duty ratio and the amplitude M of the adjustment current according to the 忒th control signal and the adjustment voltage, and the duty ratio of the adjustment current and The amplitude is reduced separately. The magnitude of the fading, 々丨L is proportional to the duty cycle of the first control signal and the magnitude of the adjustment voltage. Therefore, any one of the duty ratio of the first control signal and the adjustment voltage is separately reduced, and the adjustment current is reduced. The adjustment current decreases when the duty cycle of the first control signal and the adjustment voltage decrease simultaneously. At the same time, the magnitude of the adjustment current determines the magnitude of the operating current of the load. When the adjustment current decreases, the operating current of the load decreases. The relationship between the adjustment current and the first and second control signals may be: 1 = 314 X VxD τ 1.414 (where 'I represents the adjustment current, v represents the adjustment voltage, and D represents the duty ratio of the first control signal). Therefore, when the liquid crystal display displays a black image, the backlight driving circuit 30 provides a backlight with a small intensity. After the black image is displayed, the backlight driving circuit 30 can automatically adjust the duty ratio of the first and second control signals according to the image signal, thereby adjusting the duty ratio of the regulated current output by the inverter 33 and The amplitude causes the load 34 to emit light when displaying a black image. 20 201001387 'The brightness of the illuminating color image of the load 34 is not small, and the intensity is automatically adjusted according to the image signal during the subsequent image display. , the whiteness of the display is lowered. Douit it said that the duty cycle of the adjustment current can not be lower than the normal working mode, for example, the duty ratio is not less than 20%), and the amplitude of the adjustment current cannot be lower than the minimum value of the positive range (eg W), otherwise the effect of the image displayed by the liquid crystal display will be affected, or even the image of the dry: the phenomenon of water ripples will appear. Therefore, the liquid crystal display that adjusts the luminous intensity of the load by adjusting the amplitude alone or adjusting the amplitude separately can not be further reduced in brightness when the black image is displayed, so that the contrast can only reach ό000 · 1 -h -4- I » , a ^ 1 or so. For example, when the general liquid crystal display displays a white image, the maximum brightness is lumens, and when the black image is displayed, the brightness is 0.05 stream day and month, and the contrast is _〇: 1. In addition, in the case of the brightness of the image corresponding to the image signal, the difference in the luminous intensity of the load 34 may also cause the brightness of the image displayed by the liquid crystal display to be different. A liquid crystal display that adjusts the duty ratio of the load by individually adjusting the duty ratio or separately adjusting the amplitude to display the white image may have a smaller range of π degrees between the maximum brightness and the minimum brightness, such as displaying the maximum white image. The brightness is 300 lumens, and the white image has a minimum brightness of 67 lumens, and its brightness adjustment range is only (300-67) + 300 = 75%. When the liquid crystal display displays a black image, the first control signal can control the duty ratio of the adjustment current to a minimum value of a normal working range, and the second control signal can control the amplitude of the adjustment current to a normal working range. The minimum value, so the duty cycle and amplitude of the adjustment current can be simultaneously entered into the 21 201001387 lamp: the magnitude of the current adjustment current can be changed to be more than the case where the duty cycle or amplitude of the adjustment f stream is separately adjusted. Small, so that the liquid crystal display can not show the brightness of the black image is lower. Through the backlight drive circuit 30, (four) the duty cycle and the amplitude (four) adjustment of the entire current, the liquid crystal display can be significantly improved. For example, the liquid crystal display displays a white image. The maximum redundancy of the image can be Shan Luming. When the black image is displayed, the brightness can be as low as about 0.014 lumens, so that the contrast can reach up to 2 〇 _: The image has a good visual effect. The liquid crystal display can display a maximum brightness of 300 lumens for a white image, and a minimum brightness of 12 lumens for a white image, and the brightness adjustment range can be greatly improved to (3〇〇-12) + 3〇〇= 96%. The backlight driving circuit 3 receives the image signal corresponding to the black image. The moonlight driving circuit 3 automatically adjusts the adjusting current according to the image brightness corresponding to the received image signal to adjust the luminous intensity of the load %. Therefore, the liquid crystal display shows that a better display effect, a higher contrast effect, and better power saving performance can be obtained. The present invention is not limited to the above embodiments. For example, when the control unit 11 of the first embodiment receives the image signal corresponding to the black image, the first control signal outputted by the control 70 11 remains and The user-defined brightness value corresponds to the duty ratio 'the duty ratio of the second control signal becomes the second space ratio. In addition, the second control signal in the first embodiment may be a direct current. Hole number. After the control unit A u receives the image signal corresponding to the black image, the voltage of the control signal is - the voltage, after the control 22 201001387 unit 11 receives the image signal corresponding to the black image, The voltage of the second control signal becomes a second voltage, and the first voltage is greater than the second voltage. The first voltage can be 2.1V and the second voltage can be 〇.6v. In addition, the adjustment unit 32 in the third embodiment may be omitted. When the backlight driving circuit 30 is in a static working state, the second control signal outputted by the control unit 31 to the inverter 33 is a 21V DC voltage, and when the backlight driving circuit is in a dynamic working state, the control unit The second control signal outputted to the inverter 33 is a 6V DC voltage. The above working process can be realized by software or hardware setting inside the control unit 21. In addition, the reset circuit 311 in the second embodiment can be combined with a 〇sd unit, and the user can reset the first control signal and the second control signal by adjusting the content of the 〇SD unit. In addition, the reset circuit 311 in the third embodiment may be disposed outside the control unit 31, and the first and second control signals are reset by the control unit 31. In addition, the control unit 31 in the third embodiment can change the condition for setting the dynamic operation mode of the backlight driving power, that is, the image information = 30 can be entered into the dynamic working mode when the specific brightness value is corresponding. In addition, the second output of the control unit 21 in the second embodiment is adjusted when the backlight driving circuit 2G is in the active state, and the image brightness value corresponding to the received image signal is adjusted. (4) The voltage also changes correspondingly. If the second control signal receives the image brightness value corresponding to the image signal of 23 201001387 when the control unit 21 changes, the duty ratio corresponding to the different image brightness value is in the first-occupied The air ratio and the second duty ratio are automatically changed. The duty cycle of the second control signal can be changed by the software or hardware setting of the control unit u, and the change can be linear or nonlinear. In addition, the duty ratio of the second control signal outputted by the control unit 21 in the second embodiment may remain unchanged in the static working state and the dynamic working state. The second control signal has a first frequency in the static working state and a second frequency in the dynamic working state, the first frequency being greater than the second frequency. a first adjustment voltage, the second frequency corresponding to the second adjustment voltage. In addition, the control unit 21 in the second embodiment may output a plurality of first control signals and a plurality of second control signals, the plurality of first adjustments The duty ratio of the current is adjusted, and the plurality of second controls are used to adjust the amplitude of the current. In addition, the control unit 21 in the second embodiment may output at least one control signal when entering the dynamic working state from the static working state. The duty ratio and the frequency of the at least one control signal are respectively reduced, so that the duty ratio and the frequency of the adjustment current are respectively reduced. In addition, the control unit 21 in the second embodiment can output at least one control signal in the slave. When the static working state enters the dynamic working state, the duty ratio and the amplitude of the at least one control signal become smaller, respectively, so that the duty ratio and the amplitude of the adjusting current become smaller respectively. Further, in the second embodiment The control unit 21 can also provide a third 24 201001387 = signal to the inverter 23. The frequency of the third control signal in the static working state is greater than its dynamic work. The frequency of the state, so that the frequency of the adjustment current in the state of static jade is also greater than the frequency of its dynamic working state. In summary, the present invention has indeed met the requirements of the invention patent, and has proposed a special shot according to law. However, the description of the present invention is only a preferred embodiment of the present invention, and the present invention is not limited to the above-described embodiments, and those skilled in the art will be able to modify the equivalent modifications according to the spirit of the present invention. The following is a description of the circuit of the first embodiment of the liquid crystal display of the present invention. FIG. 2 is a schematic diagram showing the variation of the adjustment current waveform of the backlight driving circuit shown in FIG. 3 is a block diagram of a second embodiment of the liquid crystal display of the present invention, and FIG. 4 is a schematic structural diagram of the adjustment unit shown in FIG. FIG. 5 is a block diagram showing the circuit of the third embodiment of the liquid crystal display of the present invention. FIG. 7 is a schematic diagram showing the circuit structure of the adjusting unit shown in FIG. [Description of main component symbols] Backlight drive circuit 10, 20, 30 First resistor 25 201001387 Control unit 11, 21, 31 Second resistor 362 Adjustment unit 22' 32 Third resistor 371 Inverter 13, 23, 33 Fourth resistor 372 Load 14, 24, 34 First capacitor 363 Resistor 221 Second capacitor 364 Capacitor 222 Third capacitor 373 26