200912858 九、發明說明： 【發明所屬之技術領域】 本發明係關於一種驅動控制電路、背光模組及其驅動 方法，特別關於一種可保護整體電源之驅動控制電路、背 光模組及其驅動方法。 【先前技術】 隨著數位時代的來臨，液晶顯示裝置之技術亦快速成 長，已成為不可或缺的電子產品，因此對於液晶顯示裝置 之技術及功能的要求也愈來愈高。 一般而言，液晶顯示裝置係主要包含一液晶顯示面板 (Liquid Crystal Display Panel )、以及一背光模組 (Backlight Module )。其中，液晶顯示面板主要係具有兩 基板以及一夾設於兩基板間的液晶層；而背光模組係發出 均勻的光線以分佈在液晶顯示面板之表面。傳統上，係以 冷陰極螢光燈（Cold Cathode Fluorescent Lamp，CCFL)來 作為背光模組之光源，而由於冷陰極螢光燈之燈管特性， 需提供高的啟動電壓，才可啟動冷陰極螢光燈。近來，為 了避免啟動電壓過高，而造成變壓器之跳火或燒毁，故提 升背光模組之驅動功能及控制光源之發光強度已為背光 模組不可或缺的技術之一。 請參照圖1A所示，習知之一種背光模組1係包含一 控制單元11、至少一切換單元12、至少一變壓器13及至 少一冷陰極螢光燈14。在此係以背光模組1具有各一個切 200912858 換單元12、變壓器13及冷陰極螢光燈14為例。而控制單 元11係具有一預設值P01，且切換單元12電性連接於變 壓器13及控制單元11之間，冷陰極螢光燈14則與變壓 器13電性連接，其中切換單元12包含複數個開關元件。 一般係以爆發模式（burst mode)來控制冷陰極螢光燈14， 如圖1B所示，即，不調整加於冷陰極螢光燈14上的驅動 電壓之振幅，而是改變驅動電壓之責任週期（duty cycle ) 的方式，以控制冷陰極螢光燈14啟動與冷陰極螢光燈14 亮度之調整，此處之責任週期即為高電壓時間T01與一週 期時間T02之比值。 此外，再如圖1A所示，背光模組1更包含相互電性 連接之一第一電容器C1、一第二電容器C2及一回授電路 15,且第一電容器C1係電性連接於變壓器13及冷陰極螢 光燈14之間。其中，回授電路15係包括降壓及分壓用之 電阻器Rf、Rl、R2以及防止逆電流之二極體D。 背光模組1之驅動方式的作動如下：當背光模組1啟 動後，則控制單元11係產生一控制訊號S01至切換單元 12。切換單元12根據輸入之電源與控制訊號S01以切換 產生出不同極性的一次側電壓S02。變壓器13係藉由其一 次側131接收一次側電壓S02以透過二次側132感應出一 驅動訊號S03，以驅動冷陰極螢光燈14。此時，亦藉由第 一電容器C1及第二電容器C2以取得一回授訊號S04，並 透過回授電路15送至控制單元1卜控制單元11係檢測回 授訊號S04之值是否大於預設值P01，當回授訊號S04大 200912858 於預設值P01，則停止增加控制訊號SOI之值，以避免變 壓器13產生過電壓。 然而，藉由上述之驅動方式，不僅需使用高壓電容器 作為第一電容器C1及第二電容器C2,更需配合回授電路 15，且係因使用高壓電容器而使背光模組1之電路板必須 為雙層板或多層板，故更加使得整體成本提高。 因此，如何提供一種具有時序驅動程序及降低成本之 驅動控制電路、背光模組及其驅動方式，正是當前的重要 課題之一。 【發明内容】 有鑑於上述課題，本發明之目的為提供一種時序驅動 程序及降低成本之驅動控制電路、背光模組及其驅動方 式。 緣是，為達上述目的，依本發明之一種驅動方法用以 驅動一背光模組，背光模組包含複數個冷陰極榮光燈。驅 動方法包括下列步驟：於一開機時段内，逐漸增加一驅動 訊號之責任週期以點亮冷陰極螢光燈；於一閉迴路時段 内，根據冷陰極螢光燈之亮度回授訊號以調整驅動訊號之 責任週期，並接收一開路回授訊號，當判斷開路回授訊號 為異常時，進入一開路偵測時段；以及於開路偵測時段 内，於一第一預設時間内，提供一具有第一預設責任週期 之驅動訊號至冷陰極螢光燈，並持續接收開路回授訊號， 當開路回授訊號為異常時，進入一關機時段。 200912858 為達上述目的，依本發明之一種驅動控制電路包含一 控制單元、至少一切換單元以及至少一變壓器。控制單元 係接收一亮度回授訊號及一開路回授訊號，並產生至少一 驅動訊號，且控制單元係具有一第一預設責任週期及一第 二預設責任週期，並依據亮度回授訊號以調整驅動訊號。 控制單元係檢測開路回授訊號以於異常時，產生具有一第 一預設責任週期之驅動訊號，並持續接收開路回授訊號， 或控制單元產生具有一第二預設責任週期之驅動訊號。切 換單元係與控制單元電性連接，並接收及依據驅動訊號以 產生一次側電壓。變壓器係與切換單元電性連接，其係具 有一次侧及二次侧。其中一次側係接收一次側電壓，以於 二次側產生一責任週期驅動訊號驅動一發光單元。 為達上述目的，依本發明之一種背光模組包含一驅動 控制電路及至少一發光單元。驅動控制電路係具有一控制 單元、至少一切換單元以及至少一變壓器。其中控制單元 係接收一亮度回授訊號及一開路回授訊號，並產生至少一 驅動訊號。控制單元係具有一第一預設責任週期及一第二 預設責任週期，並依據亮度回授訊號以調整驅動訊號。控 制單元係檢測開路回授訊號以於異常時，產生具有一第一 預設責任週期之驅動訊號，並持續接收開路回授訊號，或 控制單元產生具有一第二預設責任週期之驅動訊號。切換 單元係與控制單元電性連接，並接收及依據驅動訊號以產 生一次側電壓。變壓器係與切換單元電性連接，其係具有 一次側及二次側。其中一次側係接收一次側電壓，以於二 200912858 次侧產生一責任週期驅動訊號。發光單元係與驅動控制電 路電性連接，以接收責任週期驅動訊號並產生亮度回授訊 號。 承上所述，因依據本發明之一種驅動控制電路、背光 模組及其驅動方法，係藉由驅動控制電路與發光單元電性 連接，並使控制單元產生驅動訊號，及接收亮度回授及開 路回授訊號，而再透過切換單元及變壓器以輸出責任週期 驅動訊號至發光單元。與習知技術相較，本發明係於電路 上除了僅使用單層板’而不需再使用習知之高壓電容外， 更於控制單元中增加第一預設責任週期及第二預設責任 週期，並分別接收自變壓器回授之開路回授訊號及自發光 單元回授之亮度回授訊號。此種方式，不僅可減少整體回 授電路’更可隨時或於不同階段而檢測開路回授訊號是否 異常’以保護並避免變壓器受到損壞，進而降低成本，並 提升背光模組之品質。 【實施方式】 以下將參照相關圖式’說明依本發明較佳實施例之驅 動控制電路、背光模組及其驅動方法。 請參照圖2所示’本發明較佳實施例之背光模組2包 含一驅動控制電路3以及至少一發光單元4。於實施上， 背光模組2係可為一直下式背光模組或一侧光式背光模 組’而發光單元4可為一冷陰極螢光燈。於此，背光模組 2係以二個發光單元4為例。 200912858 驅動控制電路3係具有一控制單元3卜至少一切換單 元32以及至少一變壓器33。本實施例之切換單元32與變 壓器33之數量係與發光單元4相對應，故在此你以驅動 控制電路3具有二個切換單元32及二個變壓器33為例。 控制單元31中可設定_第 預設責任週期P11及一 第二預設責任週期p12，分別接收一亮度回授訊號S12及 一開路回授訊號S13，並產生至少一驅動訊號S11。其中’ 控制單元31係依據亮度回授訊號S12以調整驅動訊號 S11。於實施上，亮度回授訊號S12及開路回授訊號S13 係分別為一電壓訊號或一電流訊號。 此外，控制單元31更具有，控制器或一控制晶片， 而可以依據不同需求而先行設定第一預設責任週期P11、 第二預設責任週期P12、一第〆預設時間T11及一第二預 設時間T12，其係可預先儲存或動態由外部輸入於控制單 元31中。而第一預設責任週期P11及第二預設責任週期 P12之設定方式’可藉由實驗、模擬或其他方式以取得發 光單元4之啟動電壓所對應之亮度大小。其中第二預設責 任週期P12係大於第一預設責任週期pll。 本實施例中，由於不需要使用高壓電容，因此背光模 組2可藉由單層電路板即可達到將亮度回授訊號Sl2及開 路回授訊號S13回授至控制單元31之功能。 請繼續參照圖2所示，切換單元32係與控制單元31 電性連接，並具有一橋式切換電路（圖未示），例如—全 橋式切換電路或一半橋式切換電路，而切換單元32係藉 200912858 由橋式切換電路接收及依據驅動訊號S11以產生一次侧電 壓 S14 〇 變壓器33具有一次側331及二次侧332。一次侧331 係與切換單元32電性連接，二次側332係相互串接，並 電性連接於控制單元31及發光單元4之間。 一次側331係接收一次侧電壓S14，並藉由電磁感應 方式使變壓器33依據一次侧電壓S14以於二次侧332產 生開路回授訊號S13及責任週期驅動訊號S15。本實施例 之二次側332係共同產生開路回授訊號S13。 於本實施例中，發光單元4係相互電性連接，並接收 驅動控制電路3之貴任週期驅動訊號S15以共同產生亮度 回授訊號S12。 請同時參照圖3所示’本實施例之背光模組2之驅動 方法’其作動如下··當背光模組2開機後，進入一開機時 段P〇n’背光模組,2係藉由控制單元31開始產生並持續增 加驅動訊號S11之值。驅動訊號S11係經由切換單元32 以轉換為一次側電壓S14，再透過變壓器33於其二次側 332產生責任週期驅動訊號S15及共同產生開路回授訊號 S13。責任週期驅動訊號S15驅動發光單元4，以產生亮度 回授訊號S12。亮度回授訊號S12及開路回授訊號S13則 分別回授至控制單元31，此時，背光模組2係進入閉迴路 (close loop ) B夺段 PCL。 於閉迴路時段PCL中，控制單元31係檢測開路回授訊 號S13是否異常。當開路回授訊號S13為正常時，則控制 200912858 早7G 31係繼續依據發光單元4產生之亮度回授訊號犯 而調整驅動訊號sii之值。當開路回授訊號S13為異常 時，例如：發光單元4係呈現開路狀態，此時，控制單元 31係進入一開路偵測時段p〇D。 主在開路偵測時段P〇D中，控制單元31輸出具有第一預 設責任週期P11之驅動訊號su，以經由切換單元32及變 壓器33產生責任週期驅動訊號S15以驅動發光單元‘同 時，控制單元31持續檢測開路回授訊號Sl3是否異常。 右由進入此時段後起算，直至第一預設時間Tu前，當控 制單元31檢測出開路回授訊號S13為正常時，則回到閉 迴路時段pCL。即控制單元31再次依據亮度回授訊號si2 以調整驅動訊號S11，直到控制單元31下次再檢測出開路 回授訊號S13異常為止。當開路回授訊號S13為異常時， 則進入一關機時段p〇FF 0 於關機時段P〇FF中，控制單元3 1係輸出一具有第二 預設責任週期P12之驅動訊號S11，透過切換單元32及變 壓器33產生責任週期驅動訊號S15。進入此時段並經過第 二預設時間T12後，立即關閉發光單元4。 本實施例之背光模組2,係藉由控制單元31增加第一 預没責任週期P11及第二預設責任週期P12，並分別接收 自發光單元4回授之亮度回授訊號S12及自變壓器33回 授之開路回授訊號S13。此種方式，除了電路板僅使用單 層板外’更不需再使用習知之高壓電容，更可隨時或於不 同階段而檢測開路回授訊號S13是否異常，以保護並避免 12 200912858 變壓器33受到損壞，進而降低成本，並提升背光模組2 之品質。 請參照圖4所示，本發明較佳實施例之一種背光模組 之驅動方法係應用於上述較佳實施例之背光模組2 (如圖 2所示）’且在此並以較佳實施例之背光模組2為例。背光 模組2之驅動方式係包括步驟S1至步驟S6。 步驟S1係於一開機時段内，逐漸增加一驅動訊號之 責任週期以點亮冷陰極螢光燈。步驟S2係於一閉迴路時 段内，根據冷陰極螢光燈之亮度回授訊號以調整驅動訊號 之責任週期，並接收一開路回授訊號。於本實施例中，亮 度回授訊號及開路回授訊號係可分別為一電壓訊號或電 流訊號。 步驟S3係判斷開路回授訊號是否異常。當開路回授 訊號為正常時，則回到步驟S2。當判斷開路回授訊號為異 常時，進行步驟S4。步驟S4係於於開路偵測時段内，於 一第一預設時間内，提供一具有第一預設責任週期之驅動 訊號至冷陰極螢光燈，並持續接收開路回授訊號。 步驟S5係判斷開路回授訊號是否異常。當開路回授 訊號為正常時，則回到步驟S2。當判斷開路回授訊號為異 常時，進行步驟S6。步驟S6係於關機時段中，提供一具 有第二預設責任週期之驅動訊號至冷陰極螢光燈，並於一 第二預設時間之後將驅動訊號之責任週期調整為零以關 閉冷陰極螢光燈。於實施上，第二預設責任週期係大於第 一預設責任週期，且第一預設時間及/或第二預設時間係由 13 200912858 使用者設定。 其中詳細的驅動步驟，於上述較佳實施例中，已一併 詳述，故於此不再加以贅述。 綜上所述，因依據本發明之一種驅動控制電路、背光 模組及其驅動方法，係藉由驅動控制電路與發光單元電性 連接，並使控制單元產生驅動訊號，及接收亮度回授訊號 及開路回授訊號，而再透過切換單元及變壓器以輸出責任 週期驅動訊號至發光單元。與習知技術相較，本發明係於 電路上除了僅使用單層板，而不需再使用習知之高壓電容 外，更於控制單元中增加第一預設責任週期及第二預設責 任週期，並分別接收自變壓器回授之開路回授訊號及自發 光單元回授之亮度回授訊號。此種方式，可隨時或於不同 階段檢測開路回授訊號是否異常，以保護並避免變壓器受 到損壞，進而降低成本，並提升背光模組之品質。 以上所述僅為舉例性，而非為限制性者。任何未脫離 本發明之精神與範疇，而對其進行之等效修改或變更，均 應包含於後附之申請專利範圍中。 【圖式簡單說明】 圖1A為顯示習知之一種背光模組之示意圖； 圖1B為顯示習知之冷陰極螢光燈之控制模式之示意 圖， 圖2為顯示依本發明較佳實施例之一種背光模組之示 意圖； 14 200912858 圖3為顯示依本發明較佳實施例之背光模組之時間與 責任週期大小之關係示意圖；以及 圖4為顯示依本發明較佳實施例之背光模組之驅動方 法之步驟流程示意圖。 【主要元件符號說明】 I、 2 :背光模組 II、 31 :控制單元 12、 32 :切換單元 13、 33 :變壓器 14 :冷陰極螢光燈 15 :回授電路 3:驅動控制電路 131、 331 : —次側 132、 332 :二次侧 4 :發光單元 C1 :第一電容器 C2 :第二電容器 D :二極體BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving control circuit, a backlight module, and a driving method thereof, and more particularly to a driving control circuit, a backlight module, and a driving method thereof that can protect an overall power source. [Prior Art] With the advent of the digital age, the technology of liquid crystal display devices has also grown rapidly and has become an indispensable electronic product. Therefore, the requirements for the technology and functions of liquid crystal display devices are becoming higher and higher. Generally, a liquid crystal display device mainly includes a liquid crystal display panel and a backlight module. The liquid crystal display panel mainly has two substrates and a liquid crystal layer sandwiched between the two substrates; and the backlight module emits uniform light to be distributed on the surface of the liquid crystal display panel. Traditionally, Cold Cathode Fluorescent Lamp (CCFL) is used as the light source of the backlight module, and due to the characteristics of the lamp of the cold cathode fluorescent lamp, a high starting voltage is required to start the cold cathode. Fluorescent light. Recently, in order to avoid the startup voltage from being too high, the transformer jumps or burns, so that the driving function of the backlight module and the illumination intensity of the control light source are one of the indispensable technologies for the backlight module. Referring to FIG. 1A, a conventional backlight module 1 includes a control unit 11, at least one switching unit 12, at least one transformer 13, and at least one cold cathode fluorescent lamp 14. Here, the backlight module 1 has a single cut 1212, a transformer 13, and a cold cathode fluorescent lamp 14 as an example. The control unit 11 has a preset value P01, and the switching unit 12 is electrically connected between the transformer 13 and the control unit 11, and the cold cathode fluorescent lamp 14 is electrically connected to the transformer 13, wherein the switching unit 12 includes a plurality of Switching element. Generally, the cold cathode fluorescent lamp 14 is controlled in a burst mode, as shown in FIG. 1B, that is, the amplitude of the driving voltage applied to the cold cathode fluorescent lamp 14 is not adjusted, but the responsibility of changing the driving voltage is changed. The duty cycle is used to control the cold cathode fluorescent lamp 14 to start and adjust the brightness of the cold cathode fluorescent lamp 14. Here, the duty cycle is the ratio of the high voltage time T01 to the one cycle time T02. In addition, as shown in FIG. 1A , the backlight module 1 further includes a first capacitor C1 , a second capacitor C2 , and a feedback circuit 15 electrically connected to each other, and the first capacitor C1 is electrically connected to the transformer 13 . And between the cold cathode fluorescent lamps 14. The feedback circuit 15 includes resistors Rf, R1, and R2 for buck and voltage division and a diode D for preventing reverse current. The driving mode of the backlight module 1 is as follows: After the backlight module 1 is activated, the control unit 11 generates a control signal S01 to the switching unit 12. The switching unit 12 switches to generate the primary side voltage S02 of different polarity according to the input power source and the control signal S01. The transformer 13 receives the primary side voltage S02 through its primary side 131 to induce a drive signal S03 through the secondary side 132 to drive the cold cathode fluorescent lamp 14. At this time, the first capacitor C1 and the second capacitor C2 are also used to obtain a feedback signal S04, and sent to the control unit 1 through the feedback circuit 15 to control whether the value of the feedback signal S04 is greater than a preset. The value P01, when the feedback signal S04 is 200912858 at the preset value P01, stops increasing the value of the control signal SOI to avoid the transformer 13 generating an overvoltage. However, with the driving method described above, it is necessary to use not only the high voltage capacitor as the first capacitor C1 and the second capacitor C2 but also the feedback circuit 15, and the circuit board of the backlight module 1 must be used due to the use of the high voltage capacitor. Double-layer boards or multi-layer boards make the overall cost even higher. Therefore, how to provide a driving control circuit with a timing driver and a cost reduction, a backlight module and a driving method thereof is one of the current important topics. SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide a timing driving program, a driving control circuit for reducing cost, a backlight module, and a driving method thereof. Therefore, in order to achieve the above object, a driving method according to the present invention is used to drive a backlight module, and the backlight module includes a plurality of cold cathode glory lamps. The driving method comprises the steps of: gradually increasing a duty cycle of a driving signal to illuminate the cold cathode fluorescent lamp during a power-on period; and adjusting the driving according to the brightness of the cold cathode fluorescent lamp during a closed circuit period The duty cycle of the signal, and receiving an open circuit feedback signal, when it is determined that the open circuit feedback signal is abnormal, entering an open circuit detection period; and during the open circuit detection period, providing a first preset time The driving signal of the first preset duty cycle is to the cold cathode fluorescent lamp, and continuously receives the open circuit feedback signal. When the open circuit feedback signal is abnormal, it enters a shutdown period. In order to achieve the above object, a drive control circuit according to the present invention comprises a control unit, at least one switching unit and at least one transformer. The control unit receives a brightness feedback signal and an open feedback signal, and generates at least one driving signal, and the control unit has a first preset duty cycle and a second predetermined duty cycle, and the feedback signal is according to the brightness. To adjust the drive signal. The control unit detects the open feedback signal to generate a driving signal having a first predetermined duty cycle and continuously receives the open feedback signal, or the control unit generates a driving signal having a second predetermined duty cycle. The switching unit is electrically connected to the control unit and receives and responds to the driving signal to generate a primary side voltage. The transformer system is electrically connected to the switching unit, and has a primary side and a secondary side. The primary side receives the primary side voltage to generate a duty cycle driving signal on the secondary side to drive an illumination unit. To achieve the above objective, a backlight module according to the present invention comprises a driving control circuit and at least one light emitting unit. The drive control circuit has a control unit, at least one switching unit, and at least one transformer. The control unit receives a brightness feedback signal and an open feedback signal, and generates at least one driving signal. The control unit has a first preset duty cycle and a second preset duty cycle, and adjusts the driving signal according to the brightness feedback signal. The control unit detects the open feedback signal to generate a driving signal having a first predetermined duty cycle and continuously receives the open feedback signal, or the control unit generates a driving signal having a second predetermined duty cycle. The switching unit is electrically connected to the control unit and receives and generates a primary side voltage according to the driving signal. The transformer system is electrically connected to the switching unit, and has a primary side and a secondary side. The primary side receives the primary side voltage to generate a duty cycle drive signal on the second side of 200912858. The lighting unit is electrically connected to the driving control circuit to receive the duty cycle driving signal and generate a brightness feedback signal. According to the present invention, a driving control circuit, a backlight module, and a driving method thereof are electrically connected to a light emitting unit by a driving control circuit, and the control unit generates a driving signal, and receives brightness feedback and The open circuit feedback signal is transmitted to the light emitting unit through the switching unit and the transformer to output a duty cycle. Compared with the prior art, the present invention is based on the fact that only a single layer board is used on the circuit, and the conventional high voltage capacitor is not needed, and the first preset duty cycle and the second preset duty cycle are added to the control unit. And receiving the open feedback signal from the transformer feedback and the brightness feedback signal fed back from the self-illuminating unit. In this way, not only can the overall feedback circuit be reduced, but whether the open feedback signal is abnormal at any time or at different stages can be detected to protect and avoid damage to the transformer, thereby reducing the cost and improving the quality of the backlight module. [Embodiment] Hereinafter, a drive control circuit, a backlight module, and a drive method thereof according to a preferred embodiment of the present invention will be described with reference to the related drawings. Referring to FIG. 2, the backlight module 2 of the preferred embodiment of the present invention includes a driving control circuit 3 and at least one light emitting unit 4. In practice, the backlight module 2 can be a direct-type backlight module or a side-light backlight module ′ and the illuminating unit 4 can be a cold cathode fluorescent lamp. Here, the backlight module 2 is exemplified by two light-emitting units 4. 200912858 The drive control circuit 3 has a control unit 3, at least one switching unit 32 and at least one transformer 33. The number of the switching unit 32 and the transformer 33 of the present embodiment corresponds to the light-emitting unit 4, so here, the drive control circuit 3 has two switching units 32 and two transformers 33 as an example. The control unit 31 can set a first predetermined duty cycle P11 and a second preset duty cycle p12 to receive a brightness feedback signal S12 and an open feedback signal S13, respectively, and generate at least one driving signal S11. The control unit 31 adjusts the driving signal S11 according to the brightness feedback signal S12. In practice, the brightness feedback signal S12 and the open feedback signal S13 are respectively a voltage signal or a current signal. In addition, the control unit 31 further has a controller or a control chip, and can set a first preset duty cycle P11, a second preset duty cycle P12, a second preset time T11, and a second according to different requirements. The preset time T12 is pre-stored or dynamically input into the control unit 31 by the outside. The first preset duty cycle P11 and the second preset duty cycle P12 can be set by the experiment, simulation or other means to obtain the brightness corresponding to the starting voltage of the light-emitting unit 4. The second preset responsibility period P12 is greater than the first preset responsibility period p11. In this embodiment, since the high voltage capacitor is not required, the backlight module 2 can realize the function of feeding back the brightness feedback signal S12 and the open feedback signal S13 to the control unit 31 by using a single layer circuit board. Referring to FIG. 2, the switching unit 32 is electrically connected to the control unit 31 and has a bridge switching circuit (not shown), such as a full bridge switching circuit or a half bridge switching circuit, and the switching unit 32. The circuit is received by the bridge switching circuit according to 200912858 and generates a primary side voltage S14 according to the driving signal S11. The transformer 33 has a primary side 331 and a secondary side 332. The primary side 331 is electrically connected to the switching unit 32, and the secondary side 332 is connected in series with each other and electrically connected between the control unit 31 and the light emitting unit 4. The primary side 331 receives the primary side voltage S14 and causes the transformer 33 to generate the open circuit feedback signal S13 and the duty cycle drive signal S15 on the secondary side 332 in accordance with the primary side voltage S14 by electromagnetic induction. The secondary side 332 of this embodiment collectively produces an open circuit feedback signal S13. In this embodiment, the light-emitting units 4 are electrically connected to each other and receive the noble period drive signal S15 of the drive control circuit 3 to jointly generate the brightness feedback signal S12. Referring to FIG. 3, the driving method of the backlight module 2 of the present embodiment is as follows: When the backlight module 2 is turned on, it enters a booting period P〇n' backlight module, and 2 is controlled by Unit 31 begins to generate and continues to increase the value of drive signal S11. The driving signal S11 is converted into the primary side voltage S14 via the switching unit 32, and the duty cycle driving signal S15 is generated on the secondary side 332 through the transformer 33 and the open circuit feedback signal S13 is collectively generated. The duty cycle driving signal S15 drives the light emitting unit 4 to generate a brightness feedback signal S12. The brightness feedback signal S12 and the open feedback signal S13 are respectively sent back to the control unit 31. At this time, the backlight module 2 enters a close loop B segment PCL. In the closed loop period PCL, the control unit 31 detects whether the open loop feedback signal S13 is abnormal. When the open circuit feedback signal S13 is normal, then the control system 200912858 early 7G 31 continues to adjust the value of the driving signal sii according to the brightness feedback signal generated by the light unit 4. When the open loop feedback signal S13 is abnormal, for example, the light emitting unit 4 is in an open state, and at this time, the control unit 31 enters an open circuit detecting period p〇D. In the open detection period P〇D, the control unit 31 outputs a driving signal su having a first predetermined duty cycle P11 to generate a duty cycle driving signal S15 via the switching unit 32 and the transformer 33 to drive the lighting unit' while controlling The unit 31 continuously detects whether the open feedback signal S13 is abnormal. The right is counted from the time after entering the period until the first preset time Tu, and when the control unit 31 detects that the open feedback signal S13 is normal, it returns to the closed loop period pCL. That is, the control unit 31 adjusts the driving signal S11 again according to the brightness feedback signal si2 until the control unit 31 detects the open circuit feedback signal S13 abnormally next time. When the open circuit feedback signal S13 is abnormal, it enters a shutdown period p〇FF 0 in the shutdown period P〇FF, and the control unit 31 outputs a driving signal S11 having a second preset duty cycle P12, through the switching unit. 32 and transformer 33 generate a duty cycle drive signal S15. After entering this period and after the second preset time T12, the lighting unit 4 is turned off immediately. The backlight module 2 of the embodiment is configured to increase the first pre-default duty cycle P11 and the second preset duty cycle P12 by the control unit 31, and receive the brightness feedback signal S12 and the self-transformer fed back from the light-emitting unit 4 respectively. 33 open circuit feedback signal S13. In this way, except that the circuit board only uses a single-layer board, it is no longer necessary to use the conventional high-voltage capacitor, and it is also possible to detect whether the open-circuit feedback signal S13 is abnormal at any time or at different stages to protect and avoid 12 200912858 transformer 33 being subjected to Damage, which in turn reduces costs and improves the quality of the backlight module 2. Referring to FIG. 4, a driving method of a backlight module according to a preferred embodiment of the present invention is applied to the backlight module 2 (shown in FIG. 2) of the above preferred embodiment, and is preferably implemented herein. For example, the backlight module 2 is taken as an example. The driving method of the backlight module 2 includes steps S1 to S6. Step S1 is to gradually increase the duty cycle of a driving signal to illuminate the cold cathode fluorescent lamp during a power-on period. Step S2 is to feedback the signal according to the brightness of the cold cathode fluorescent lamp to adjust the duty cycle of the driving signal in a closed loop period, and receive an open feedback signal. In this embodiment, the brightness feedback signal and the open feedback signal can be respectively a voltage signal or a current signal. Step S3 determines whether the open feedback signal is abnormal. When the open circuit feedback signal is normal, the process returns to step S2. When it is judged that the open feedback signal is abnormal, step S4 is performed. Step S4 is to provide a driving signal with a first predetermined duty cycle to the cold cathode fluorescent lamp during a first preset time period, and continuously receive the open circuit feedback signal. Step S5 determines whether the open feedback signal is abnormal. When the open circuit feedback signal is normal, the process returns to step S2. When it is judged that the open feedback signal is abnormal, step S6 is performed. Step S6 is to provide a driving signal with a second preset duty cycle to the cold cathode fluorescent lamp during the shutdown period, and adjust the duty cycle of the driving signal to zero after a second preset time to turn off the cold cathode fluorescent Lights. In implementation, the second preset duty cycle is greater than the first preset duty cycle, and the first preset time and/or the second preset time is set by the user of 13 200912858. The detailed driving steps are detailed in the above preferred embodiments, and thus will not be further described herein. In summary, the driving control circuit, the backlight module and the driving method thereof are electrically connected to the lighting unit by the driving control circuit, and the control unit generates the driving signal and receives the brightness feedback signal. And the open circuit feedback signal, and then the switching unit and the transformer are used to output the duty cycle driving signal to the light emitting unit. Compared with the prior art, the present invention is based on the circuit, except that only a single layer board is used, and the conventional high voltage capacitor is not needed, and the first preset duty cycle and the second preset duty cycle are added to the control unit. And receiving the open feedback signal from the transformer feedback and the brightness feedback signal fed back from the self-illuminating unit. In this way, it is possible to detect whether the open feedback signal is abnormal at any time or at different stages to protect and prevent the transformer from being damaged, thereby reducing the cost and improving the quality of the backlight module. The above is intended to be illustrative only and not limiting. Any equivalent modifications or alterations to the spirit and scope of the present invention are intended to be included in the scope of the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1A is a schematic view showing a conventional backlight module; FIG. 1B is a schematic view showing a control mode of a conventional cold cathode fluorescent lamp, and FIG. 2 is a view showing a backlight according to a preferred embodiment of the present invention. FIG. 3 is a schematic diagram showing the relationship between the time and the duty cycle of the backlight module according to the preferred embodiment of the present invention; and FIG. 4 is a diagram showing the driving of the backlight module according to the preferred embodiment of the present invention. Schematic diagram of the steps of the method. [Description of main component symbols] I, 2: backlight module II, 31: control unit 12, 32: switching unit 13, 33: transformer 14: cold cathode fluorescent lamp 15: feedback circuit 3: drive control circuit 131, 331 : - Secondary side 132, 332 : Secondary side 4 : Light-emitting unit C1 : First capacitor C2 : Second capacitor D : Diode
Rl、R2、Rf :電阻器 P01 :預設值 P11 :第一預設責任週期 P12 ··第二預設責任週期 S01 :控制訊號 15 200912858 S02 ： 一次側電壓 S03 ： 驅動訊號 S04 ： 回授訊號 S11 ： 驅動訊號 S12 ： 亮度回授訊號 S13 ： 開路回授訊號 S14 ： 一次側電壓 S15 ： 責任週期驅動訊號 T01 ： 尚電壓時間 T02 ： 週期時間 T11 ： 第一預設時間 T12 ： 第二預設時間 P〇N : 開機時段 PCL ： 閉迴路時段 P〇D : 開路偵測時段 P〇FF : 關機時段 S1-S6:背光模組之驅動方法之步驟 16Rl, R2, Rf: Resistor P01: preset value P11: first preset duty cycle P12 · second predetermined duty cycle S01: control signal 15 200912858 S02 : primary side voltage S03 : drive signal S04 : feedback signal S11 : Drive signal S12 : Brightness feedback signal S13 : Open feedback signal S14 : Primary voltage S15 : Responsibility cycle drive signal T01 : Voltage time T02 : Cycle time T11 : First preset time T12 : Second preset time P〇N : PCL during power-on period: closed loop period P〇D : open circuit detection period P〇FF : shutdown period S1-S6: step 16 of driving method of backlight module