200849178 九、發明說明： 【發明所屬之技術領域】 、本發明係關於-種背光模組、液晶顯示裝置及其控制 【先前技術】 、隨著顯示科技的發展，顯示裝置及其產品已經廣泛地 被人們使用，而液晶顯示裝置因具有體型輕薄、低功率消 ^以及無輻射等優越特性，已經漸漸地取代傳統陰極射線 笞”、員示衣置，並且應用至許多種類之電子產品。 ^ 般來5兒，習知之液晶顯示裝置係分別控制一 =光模、、且之發光及一液晶顯示面板之光穿透率以顯 示不同晝面。 〜 睛芩照圖1所示，其係顯示上述液晶顯示裝置 中，光線党度及光穿透率隨時間變化時，晝面之晝 素7C度Ik B守間變化的關係。光線亮度係以5〇%的責 任週，（duty cycle)來控制.及驅動背光模組為例。其 中於％*間tu之則，液晶顯示面板係控制光穿透率維 持於Tu ’俾使液晶顯示裝置所顯示之畫素亮度依照 光線亮度及光穿透率的乘積而呈正常變化。 ^而於時間tu之後，液晶顯示面板係控制光穿透 率降至Τη ’以期晝素亮度亦可對應降低。然而，由 於受到液晶反應速度的限制而造成於時間之 後’光穿透率仍未如預期降低至Τι2而導致液晶顯示 200849178 裝置所顯示之晝素亮度產生額外的亮度LPeak，進而 使得液晶顯不裝置所顯不的晝面品質不良。 近來，業者為了解決上述問題，一般會以降低 責任週期來控制及驅動背光模組發光，以減少產生 額外的亮度LPeak。其中，為了降低光線的責任週期， 背光模組必須以較高的電流位準來驅動，而導致背 光模組的壽命降低。另外，電流位準亦無法無限制 提高，因此無法有效減少產生額外的亮度LPeak。 因此，如何提供一種可以不需改變控制及驅動背光 模組發光的責任週期，卻仍可有效減少額外的亮度 產生的背光模組、液晶顯示裝置及其控制方法，正是當前 顯示器產業的重要課題之一。 【發明内容】 有鑑於上述課題，本發明之目的為提供一種可以不需 改變光線的責任週期，卻仍可有效減少額外的亮度 產生的背光模組、液晶顯示裝置及其控制方法。 緣是，為達上述目的，依據本發明之一種背光模組係 包含一發光單元及一控制單元。控制單元係以一責任週期 控制發光單元輸出一光線。其中於一第一時距内’光線之 亮度係為一第一位準，於一第二時距内，光線之亮度係由 第一位準缓變為一第二位準。上述之責任週期係定義為第 二時距與第一時距及第二時距之和的比值。 為達上述目的，依據本發明之一種背光模組之控制方 6 200849178 法，其中背光模組係具有一控制單元及一發光單元。控制 單元係以一責任週期控制發光單元輸出一光線，控制方法 係包含下列步驟：首先，於一第一時距内，光線之亮度係 為一第一位準；然後，於一第二時距内，光線之亮度係由 第一位準缓變為一第二位準，其中責任週期係定義為第二 時距與第一時距及第二時距之和的比值。 為達上述目的，依據本發明之一種液晶顯示裝置係包 含一液晶顯示面板及一背光模組。背光模組係具有一發光 單元及一控制單元。控制單元係以一責任週期控制發光單 元輸出一光線至液晶顯示面板。其中於一第一時距内，光 線之亮度係為一第一位準，於一第二時距内，光線之亮度 係由第一位準缓變為一第二位準。上述之責任週期係定義 為第二時距與第一時距及第二時距之和的比值。 為達上述目的，依據本發明之一種液晶顯示裝置之控 制方法，其中液晶顯示裝置係具有一液晶顯示面板及一背 光模組，背光模組係具有一控制單元及一發光單元。控制 單元係以一責任週期控制發光單元輸出一光線至液晶顯 示面板，且控制方法包含下列步驟：首先，於一第一時距 内，光線之亮度係為一第一位準；然後，於一第二時距内， 光線之亮度係由第一位準缓變為一第二位準，其中責任週 期係定義為第二時距與第一時距及第二時距之和的比值。 承上所述，因依據本發明之背光模組、液晶顯示裝置 及其控制方法係於第二時距内，光線之亮度由第一位準緩 變為第二位準，換言之，本發明之背光模組、液晶顯示裝 7 200849178 置及其控制方法係透過控制於不同時距内之光線之亮度 的位準變化以降低額外的亮度的產生，而不需改變光 線的責任週期，不僅可確保顯示晝面的品質，而且 可避免背光模組的使用壽命降低。 【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背 光模組、液晶顯示裝置及其控制方法。 [較佳實施例之液晶顯示裝置] 請參照圖2所示，較佳實施例之液晶顯示裝置2 係包含一液晶顯示面板21及一背光模組22。 液晶顯示面板21具有一晝素陣列211及一驅動單元 212，其中驅動單元212可驅動晝素陣列211之液晶旋轉， 俾使光穿透率T2〇改變。 背光模組22具有一發光單元221及一控制單元222， 其中控制單元222係以一責任週期D2G控制發光單元221 輸出一光線B2〇至液晶顯示面板21之晝素陣列211。 請同時參照圖2及圖3a所示，責任週期D20係定義為 一第二時距ti2與一第一時距ti]L及第二時距ti2之和的比值 (，^+ί2χΐ〇〇% )。於第一時距内，光線之亮度係為一第 一位準L21，且於第二時距ti2内，光線之亮度係依據一關 係S20由第一位準L21緩變為一第二位準L22，在本實施例 中，第一位準L21係小於第二位準L22。其中關係S20可依200849178 IX. Description of the invention: [Technical field to which the invention pertains] The present invention relates to a backlight module, a liquid crystal display device and control thereof [Prior Art] With the development of display technology, display devices and products thereof have been widely used It has been used by people, and the liquid crystal display device has gradually replaced the traditional cathode ray 、, and has been applied to many kinds of electronic products due to its superior characteristics such as slimness, low power consumption, and no radiation. In the past 5, the conventional liquid crystal display device controls the light transmittance of a light mode, a light source, and a liquid crystal display panel to display different pupil planes. In the liquid crystal display device, when the light party degree and the light transmittance change with time, the relationship between the 昼 昼 7C degree Ik B 守 守 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 And driving the backlight module as an example. In the case of %*, the liquid crystal display panel controls the light transmittance to be maintained at Tu '俾, so that the pixel brightness displayed by the liquid crystal display device is in accordance with the light. The product of the line brightness and the light transmittance changes normally. ^And after the time tu, the liquid crystal display panel controls the light transmittance to fall to Τ', so that the brightness of the element can be reduced accordingly. However, due to the liquid crystal reaction speed The limitation of the light transmittance after the time has not decreased to Τι2 as expected, resulting in the brightness of the halogen displayed by the liquid crystal display 200849178 device generating additional brightness LPeak, thereby making the liquid crystal display device not showing the quality of the surface In order to solve the above problems, the industry generally controls and drives the backlight module to reduce the duty cycle to reduce the generation of additional brightness LPeak. Among them, in order to reduce the responsibility cycle of the light, the backlight module must be higher. The current level is driven to reduce the life of the backlight module. In addition, the current level cannot be increased without limitation, so it is impossible to effectively reduce the extra brightness LPeak. Therefore, how to provide a backlight module without changing the control and driving The backlight cycle of the group's illumination, but still effectively reduces the brightness of the backlight module, The crystal display device and its control method are one of the important topics in the current display industry. SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide a duty cycle that does not require changing light, but still effectively reduces additional The backlight module, the liquid crystal display device and the control method thereof are provided. For the above purpose, a backlight module according to the present invention comprises a light emitting unit and a control unit. The control unit is controlled by a duty cycle. The light emitting unit outputs a light, wherein the brightness of the light is at a first level in a first time interval, and the brightness of the light is changed from the first level to the second position in a second time interval. The above-mentioned responsibility cycle is defined as the ratio of the second time interval to the sum of the first time interval and the second time interval. In order to achieve the above object, the backlight module control method according to the present invention is 6200849178, wherein the backlight The module has a control unit and a lighting unit. The control unit controls the illumination unit to output a light with a duty cycle. The control method comprises the following steps: First, in a first time interval, the brightness of the light is a first level; then, at a second time interval The brightness of the light is changed from the first level to the second level, wherein the duty cycle is defined as the ratio of the second time interval to the sum of the first time interval and the second time interval. To achieve the above object, a liquid crystal display device according to the present invention comprises a liquid crystal display panel and a backlight module. The backlight module has a light emitting unit and a control unit. The control unit controls the light emitting unit to output a light to the liquid crystal display panel in a duty cycle. In a first time interval, the brightness of the light line is a first level, and in a second time interval, the brightness of the light changes from a first level to a second level. The above duty cycle is defined as the ratio of the second time interval to the sum of the first time interval and the second time interval. In order to achieve the above object, a liquid crystal display device has a liquid crystal display panel and a backlight module according to the present invention. The backlight module has a control unit and a light emitting unit. The control unit controls the illumination unit to output a light to the liquid crystal display panel in a duty cycle, and the control method comprises the following steps: First, in a first time interval, the brightness of the light is a first level; then, in a In the second time interval, the brightness of the light is changed from the first level to the second level, wherein the duty cycle is defined as the ratio of the second time interval to the sum of the first time interval and the second time interval. According to the above description, the backlight module, the liquid crystal display device and the control method thereof according to the present invention are in the second time interval, and the brightness of the light is changed from the first level to the second level. In other words, the present invention The backlight module and the liquid crystal display device 7 200849178 and the control method thereof reduce the generation of additional brightness by controlling the level change of the brightness of the light in different time intervals without changing the duty cycle of the light, which not only ensures The quality of the face is displayed, and the life of the backlight module is reduced. [Embodiment] Hereinafter, a backlight module, a liquid crystal display device, and a control method thereof according to a preferred embodiment of the present invention will be described with reference to the related drawings. [Liquid Crystal Display Device of Preferred Embodiment] Referring to FIG. 2, the liquid crystal display device 2 of the preferred embodiment includes a liquid crystal display panel 21 and a backlight module 22. The liquid crystal display panel 21 has a pixel array 211 and a driving unit 212. The driving unit 212 can drive the liquid crystal of the pixel array 211 to rotate, so that the light transmittance T2 is changed. The backlight module 22 has a light emitting unit 221 and a control unit 222. The control unit 222 controls the light emitting unit 221 to output a light B2 to the pixel array 211 of the liquid crystal display panel 21 in a duty cycle D2G. Referring to FIG. 2 and FIG. 3a at the same time, the duty cycle D20 is defined as the ratio of the second time interval ti2 to the sum of the first time interval ti]L and the second time interval ti2 (, ^+ί2χΐ〇〇% ). In the first time interval, the brightness of the light is a first level L21, and in the second time interval ti2, the brightness of the light is gradually changed from the first level L21 to a second level according to a relationship S20. L22. In this embodiment, the first level L21 is smaller than the second level L22. The relationship S20 can be
B 200849178 據實際狀況而有不同的設計，例如，言主表 所示，關係S2。可呈一直線狀(如;'干;、回a至圖3h 圖3b所干Η γ仏， 口 a所不）、一階梯狀（如 可於不同時二， 3 e所:：:二套用不同的闕係S 2。，舉例來說，如圖 線狀）由第—准’光線之亮度係依據闕係S2〇(直 光缞之h、㈣為第二位準k。於時距ti2内， ΐί Γ/2；；Γ ti4"JS20« 踝狀)由弟-位準l21緩變為第二位準l22。 另外，關係S2G亦可由兩部分所構成 二，_使光線之亮度由第一位 m平L·22 ’而關係s之另一邱公 乃邛刀S22⑴係使光線之亮度維 一二—一位準L22 (如圖3f〜圖3i所示）。在本實施例中， :第，l23與第二時距ti2之一部分ti2i的乘積減去於 =^距ti2之一部分hi中光線之亮度總和（第二時距ti2 之々"卩二ti21與關係S20之一部分S21⑴所圍成的面積）實質 上等於第—時距ti2之另—部分h中光線之亮度（第二時距 ti2之另一部分ti22與關係之另一部分S22(t)所圍成的面 積）、、心和減去第二位準Lu與第二時距h之另一部分^2的 乘積’如下述公式所示： ....................................公式 乂當然，亦可於不同時間下，呈現不同關係S2〇(具有部 刀S21⑴及部分S22(t))，在此容不贅述。 承上，再印參A?、圖2所示，因依據本發明之液晶顯示 200849178 裝置2係於第二時距ti2内，光線B20之亮度由第一位準L21 缓變為第二位準L22,俾使於第二時距ti2中，晝素陣列211 之光穿透率T2〇與光線B2〇之亮度的乘積為最小，來降低 額外的亮度的產生。如此一來，不僅可確保顯示晝 面的品質，而且可避免背光模組22因為提高驅動訊 號而使得使用壽命降低。 除此之外，請參照圖4所示，光線B2G之亮度係以與 一液晶反應關係約成反比之關係S20由第一位準L21緩變 為第二位準L22，俾使於第二時距ti2中，晝素陣列211之 光穿透率T2〇與光線B2〇之亮度的乘積為最小，來降低額 外的亮度的產生。而液晶反應關係係定義反應時間與晝 素陣列211之光穿透率T2〇之間的關係，且液晶反應關係 係與壞境溫度、液晶材料、驅動液晶轉動的前後顯不灰階 值等有關。 其中，液晶顯示裝置2更可包含一圖框輸入模組23、 一圖框緩衝模組24、一分析模組25、一過驅動值產生模 組26及一圖框輸出模組27。圖框緩衝模組24係與圖框輸 入模組23電性連接，以輸出複數個晝素P2G之複數個顯示 灰階值G21至分析模組25。而圖框輸入模組23係輸出該 等晝素P2G之複數個待顯示灰階值G22至分析模組25。分 析模組25係依據該等顯示灰階值G21之至少其中之一及該 等待顯示灰階值G22之至少其中之一，以即時運算或比對 表比對等方式而得與液晶反應關係約成反比之關係S20。 控制單元222係依據關係S2G及責任週期D2G以控制發光 200849178 單元221輸出光線B20。 過驅動值產生模組26係分別與圖框輸入模組23及圖 框緩衝模組24電性連接，以依據該等顯示灰階值G21之至 少其中之一及該等待顯示灰階值G22之至少其中之一，以 即時運算或比對表比對等方式而得到一過驅動值V20。圖 框輸出模組27係輸出過驅動值V20至驅動單元212以驅動 晝素陣列211。 承上，因依據本發明之液晶顯示裝置係於第二時距 内，光線之亮度由第一位準緩變為第二位準，且第二時距 内亮度與光穿透率的乘積，係可補償於第一時距内亮度與 光穿透率的乘積，以使得人眼可以感受到正確的顯示資 料。簡而言之，本發明之液晶顯示裝置係透過控制於不同 時距内光線之亮度的位準變化以降低額外的亮度的產 生，而不需降低光線的責任週期，不僅可確保顯示 晝面的品質，而且可避免背光模組的使用壽命降低。 [較佳實施例之液晶顯示裝置之控制方法] 請參照圖5所示，較佳實施例之液晶顯示裝置之 控制方法，其中液晶顯不裝置係具有一液晶顯不面板及一 背光模組，背光模組係具有一控制單元及發光單元，控制 單元係以一責任週期控制發光單元輸出一光線至液晶顯 示面板，且控制方法包含步驟S100至步驟S110。 步驟S100係於一第一時距内，由控制單元控制發光 單元所輸出光線之亮度為一第一位準。 步驟S110係於一第二時距内，由控制單元控制發光 11 200849178 - 單元所輸出光線之亮度由第一位準缓變為一第二位準，其 . 中責任週期係定義為第二時距與第一時距及第二時距之 和的比值。 本實施例之液晶顯示裝置之控制方法已於上述液晶 顯示裝置2中詳述（如圖2、圖3a至圖3i及圖4所示），在 此容不贅述。 [較佳實施例之背光模組] 請參照圖6所示，較佳實施例之背光模組22係包 含發光單元221及控制單元222，控制單元222係以責任 週期D2G控制發光單元221輸出光線B2G，責任週期D20 係定義為第二時距ti2與第一時距tu及第二時距ti2之和的 比值。於一第一時距内，光線之亮度係為一第一位準 L21，且於一第二時距。内，光線之亮度係依據一關係s20 由第一位準L21缓變為一第二位準L22。 本實施例之背光模組22已於上述液晶顯示裝置2中 背光模組22中詳述(如圖2、圖3a至圖3i及圖4所示）， 在此容不贅述。 [較佳實施例之背光模組之控制方法] 請參照圖7所示，較佳實施例之背光模組之控制 方法，其中背光模組係具有一控制單元及發光單元，控制 - 單元係以一責任週期控制發光單元輸出一光線，控制方法 - 係包含步驟S200至步驟S210。 步驟S200係於一第一時距内，由控制單元控制發光 單元所輸出光線之亮度為一第一位準。 12 200849178 步驟S210係於一第二時距内，由控制單元控制發光 單元所輸出光線之亮度由第一位準緩變為一第二位準，其 中責任週期係定義為第二時距與第一時距及第二時距之 和的比值。 本實施例之背光模組之控制方法已於上述液晶顯示 裝置2中詳述（如圖2、圖3a至圖3i及圖4所示），在此容 不贅述。 綜上所述，因依本發明之背光模組、液晶顯示裝置及 其控制方法係於第二時距内，光線之亮度由第一位準緩變 為第二位準，換言之，本發明之背光模組、背光模組之控 制方法、液晶顯示裝置及液晶顯示裝置之控制方法係透過 控制於不同時距内光線之亮度的位準變化以降低額外的 亮度的產生，而不需改變光線的責任週期，不僅可 確保顯示晝面的品質，而且可避免背光模組的使用 壽命降低。 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1顯示習知液晶顯示裝置中，光線亮度及光穿 透率隨時間變化時，晝面之晝素亮度隨時間變化的 關係； 圖2係顯示本發明較佳實施例之一液晶顯示裝置； 13 200849178 圖3a至圖3i係顯示圖2之液晶顯示裝置中，發光單 元所輸出之光線強度隨時間的變化； 圖4係顯示本發明較佳實施例之另一液晶顯示裝置； 圖5係顯示本發明較佳實施例之液晶顯示裝置之控制 方法， 圖6係顯示本發明較佳實施例之背光模組；以及 圖7係顯示本發明較佳實施例之背光模組之控制方 法0 元件符號說明： 2 ·液晶顯不裝置 21 ·液晶顯不面板 211 :晝素陣列 212 :驅動單元 22 :背光模組 221 :發光單元 222 :控制單元 23 :圖框輸入模組 24 :圖框缓衝模組 25 :分析模組 26 :過驅動值產生模組 27 :圖框輸出模組 B20 ·光線 D20 :責任週期 14 200849178 g21 :顯示灰階值 G22 :待顯示灰階值 L21 第一位準 L22 第二位準 L23 第三位準 LPeak :額外的亮度 ?20 ： 晝素 $20: 關係 s21(t) ··部分 S22(t):另一部分 S10C 1〜S110 :步驟 S200 1〜S210 :步驟 tu、 tl2 :時間 til · 第一時距 ti2 ： 第二時距 ti21 ： 一部分 ti22 : 另一部分 tiO : 時距 ti4 : 時距 Tn、 T12、τ2〇:光穿 V2〇 ： 過驅動值 15B 200849178 There are different designs depending on the actual situation, for example, as shown in the main table, relationship S2. It can be in a straight line (eg; 'dry; back to a figure 3h, Figure 3b, dry 仏 仏, mouth a not), a step (if at different times, 3 e::: two sets of different The 阙S 2 , for example, as shown in the figure, is based on the brightness of the first-quasi-light, which is based on the 阙S2〇 (the straight 缞 h, (4) is the second level k. Within the time interval ti2 , ΐί Γ/2;; Γ ti4"JS20« 踝 )) from the younger-level l21 slowly changed to the second level l22. In addition, the relationship S2G can also be composed of two parts, _ so that the brightness of the light is from the first position m to L·22 ', and the other relationship of the s, Qiu Gong Nai Shovel S22 (1), makes the brightness of the light one or two - one standard L22 (as shown in Figure 3f to Figure 3i). In the present embodiment, the product of the first portion ti2i of the first, l23 and the second time interval ti2 is subtracted from the sum of the luminances of the light in the portion hi of the distance ti2 (the second time interval ti2) " The area enclosed by a portion S21(1) of the relationship S20 is substantially equal to the brightness of the light in the other portion h of the first-time interval ti2 (the other portion ti22 of the second time interval ti2 is surrounded by another portion S22(t) of the relationship) The area, the heart, and the product of subtracting the second level Lu from the other part of the second time interval ^2 are as shown in the following formula: ................ ....................Forms 乂 Of course, different relationships can also be presented at different times S2〇 (with part knife S21(1) and part S22(t)), This content is not described here. As shown in Fig. 2, since the liquid crystal display 200849178 device 2 according to the present invention is in the second time interval ti2, the brightness of the light B20 is gradually changed from the first level L21 to the second level. L22, in the second time interval ti2, the product of the light transmittance T2 昼 of the halogen array 211 and the brightness of the light B2 为 is minimized to reduce the generation of additional brightness. In this way, not only the quality of the display surface can be ensured, but also the backlight module 22 can be prevented from lowering the service life by increasing the driving signal. In addition, as shown in FIG. 4, the brightness of the light B2G is inversely proportional to the liquid crystal reaction relationship S20 from the first level L21 to the second level L22, and the second time is From ti2, the product of the light transmittance T2 昼 of the halogen array 211 and the brightness of the light B2 为 is minimized to reduce the generation of additional brightness. The liquid crystal reaction relationship defines the relationship between the reaction time and the light transmittance T2〇 of the halogen array 211, and the liquid crystal reaction relationship is related to the ambient temperature, the liquid crystal material, and the gray-scale value before and after the driving of the liquid crystal. . The liquid crystal display device 2 further includes a frame input module 23, a frame buffer module 24, an analysis module 25, an overdrive value generating module 26, and a frame output module 27. The frame buffer module 24 is electrically connected to the frame input module 23 to output a plurality of display gray scale values G21 of the plurality of pixels P2G to the analysis module 25. The frame input module 23 outputs a plurality of gray scale values G22 to be displayed of the pixels P2G to the analysis module 25. The analysis module 25 is configured to react with the liquid crystal according to at least one of the display gray scale values G21 and at least one of the waiting display gray scale values G22 by an instant operation or a comparison table. Inversely proportional to the relationship S20. The control unit 222 controls the illumination according to the relationship S2G and the duty cycle D2G. The unit 221 outputs the light B20. The overdrive value generating module 26 is electrically connected to the frame input module 23 and the frame buffer module 24, respectively, to display at least one of the grayscale values G21 and the waiting display grayscale value G22. At least one of them obtains an overdrive value V20 by an instant operation or a comparison table. The frame output module 27 outputs an overdrive value V20 to the drive unit 212 to drive the pixel array 211. According to the above, the liquid crystal display device according to the present invention is in the second time interval, the brightness of the light is gradually changed from the first level to the second level, and the product of the brightness and the light transmittance in the second time interval is The product of the brightness and the light transmittance in the first time interval can be compensated so that the human eye can feel the correct display material. In short, the liquid crystal display device of the present invention reduces the generation of additional brightness by controlling the level change of the brightness of the light at different time intervals, without reducing the duty cycle of the light, and not only ensuring the display of the surface. Quality, and can avoid the life of the backlight module is reduced. [Manufacturing Method of Liquid Crystal Display Device of Preferred Embodiment] Referring to FIG. 5, a control method of a liquid crystal display device according to a preferred embodiment, wherein the liquid crystal display device has a liquid crystal display panel and a backlight module. The backlight module has a control unit and a light-emitting unit. The control unit controls the light-emitting unit to output a light to the liquid crystal display panel in a duty cycle, and the control method includes steps S100 to S110. Step S100 is performed within a first time interval, and the brightness of the light output by the light-emitting unit is controlled by the control unit to be a first level. Step S110 is performed within a second time interval, and the control unit controls the illumination 11200849178 - the brightness of the light outputted by the unit is changed from the first level to the second level, wherein the responsibility period is defined as the second time. The ratio of the distance to the sum of the first time interval and the second time interval. The control method of the liquid crystal display device of the present embodiment has been described in detail in the above liquid crystal display device 2 (as shown in Figs. 2, 3a to 3i and 4), and will not be described herein. [Backlight Module of the Preferred Embodiment] Referring to FIG. 6, the backlight module 22 of the preferred embodiment includes a light emitting unit 221 and a control unit 222. The control unit 222 controls the light output unit 221 to output light with a duty cycle D2G. B2G, the duty cycle D20 is defined as the ratio of the second time interval ti2 to the sum of the first time interval tu and the second time interval ti2. In a first time interval, the brightness of the light is a first level L21 and at a second time interval. The brightness of the light is gradually changed from the first level L21 to the second level L22 according to a relationship s20. The backlight module 22 of the present embodiment has been described in detail in the backlight module 22 of the liquid crystal display device 2 (as shown in FIG. 2, FIG. 3a to FIG. 3i and FIG. 4), and details are not described herein. [Control Method of Backlight Module of Preferred Embodiment] Referring to FIG. 7 , a control method of a backlight module according to a preferred embodiment, wherein the backlight module has a control unit and a light emitting unit, and the control unit is A duty cycle control lighting unit outputs a light, and the control method includes steps S200 to S210. Step S200 is performed within a first time interval, and the brightness of the light output by the light emitting unit is controlled by the control unit to be a first level. 12 200849178 Step S210 is within a second time interval, and the brightness of the light output by the light-emitting unit controlled by the control unit is changed from the first level to the second level, wherein the duty cycle is defined as the second time interval and The ratio of the sum of the first time interval and the second time interval. The control method of the backlight module of the present embodiment has been described in detail in the above liquid crystal display device 2 (as shown in Figs. 2, 3a to 3i and 4), and will not be described herein. In summary, the backlight module, the liquid crystal display device and the control method thereof according to the present invention are in the second time interval, and the brightness of the light is changed from the first level to the second level. In other words, the present invention The backlight module, the control method of the backlight module, the liquid crystal display device and the control method of the liquid crystal display device reduce the generation of additional brightness by controlling the level change of the brightness of the light at different time intervals without changing the light. The duty cycle not only ensures the quality of the painted surface, but also reduces the life 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. 1 is a diagram showing the relationship between the brightness of a pupil surface and the temporal change of light when the brightness and light transmittance of a conventional liquid crystal display device change with time; FIG. 2 shows a preferred embodiment of the present invention. A liquid crystal display device; 13 200849178 FIG. 3a to FIG. 3i are diagrams showing changes in light intensity outputted by the light emitting unit in the liquid crystal display device of FIG. 2; FIG. 4 is another liquid crystal display showing a preferred embodiment of the present invention. FIG. 5 is a diagram showing a control method of a liquid crystal display device according to a preferred embodiment of the present invention, FIG. 6 is a backlight module showing a preferred embodiment of the present invention; and FIG. 7 is a backlight module showing a preferred embodiment of the present invention. Control method 0 Component symbol description: 2 · Liquid crystal display device 21 · Liquid crystal display panel 211 : Alizarin array 212 : Drive unit 22 : Backlight module 221 : Light-emitting unit 222 : Control unit 23 : Frame input module 24 : Frame buffer module 25 : Analysis module 26 : Overdrive value generation module 27 : Frame output module B20 · Light D20 : Responsibility cycle 14 200849178 g21 : Display gray scale value G22 : Gray scale value to be displayed L21First position L22 Second level L23 Third level LPeak: Extra brightness? 20: Elemental $20: Relationship s21(t) · Part S22(t): Another part S10C 1~S110: Step S200 1~ S210: Steps tu, tl2: Time til · First time interval ti2: Second time interval ti21: Part ti22: Another part tiO: Time interval ti4: Time interval Tn, T12, τ2 〇: Light wear V2 〇: Overdrive value 15