200813975 九、發明說明： 【發明所屬之技術領域】 本發明係有關-種顯示裝置及其亮度控制方法，尤指 -種根據影像訊號之亮度分析結果來控制背光模組之顯 示裝置及其亮度控制方法。 【先前技術】 決定顯示器顯像品質之諸多因素中，對比值為一關鍵 因素，尤其對液晶顯示器（liquidcrystaldisplay LcD)來 說。其中’如液晶顯示面板之特性、影像訊號品質或液晶 顯示面板m等等’皆可影響對比值大小。因此，業界 長久以來係積極尋求顯示器其對比值的改善方法，也已發 展出若干相關技術。然*，傳統技術仍未有效加強對比值。 【發明内容】 本毛月之主要目的在於提供—種根據影像訊號之亮 度分析結果來控制背光模組之顯示裝置及其亮度控制方 法0 本發明揭露一種顯示裝置，包含有接收電路、影像處 理ί路、顯示單元、亮度分析電路、背光餘以及背光控 制單元。接收電路用以處理所接收之輸人訊號，以產生影 像訊號。影像處理電路_接收電路，並用以處理影像訊 200813975 號以產生驅動訊號。顯示單元耦接影像處理電路，並在驅 動訊號之驅動下而顯示影像訊號之對應内容。亮度分析電 路耦接接收電路，並用以分析影像訊號以產生一亮度分析 結果。背光模組用以提供顯示單元所需之背光。背光控制 單元耦接亮度分析電路及背光模組，並用以根據亮度分析 結果來產生控制訊號至背光模組，以控制背光模組。 本發明另揭露一種控制電路，用來控制顯示單元及背 光模組，背光模組用以提供顯示單元所需之背光。控制電 路包含有影像處理電路、亮度分析電路以及背光控制單 元。影像處理電路用以接收並處理包含有複數個晝面資料 之影像訊號，該顯示單元係用來顯示該晝面資料。亮度分 析電路用來接收該影像訊號並分析該影像訊號之亮度 值，以產生亮度分析結果。背光控制單元耦接亮度分析電 路，用以根據亮度分析結果來產生控制訊號至背光模組， 以控制背光模組。 本發明另揭露一種亮度控制方法，用於一顯示裝置， 該顯示裝置包含有顯示單元及背光模組，該方法係控制顯 示單元顯示影像訊號之對應内容，並控制背光模組提供至 該顯示單元之背光。該方法包含有··（a)處理影像訊號以產 生驅動訊號來驅動該顯示單元；（b)顯示影像訊號之對應内 容；（c)分析影像訊號以產生亮度分析結果；以及（d)根據亮 度分析結果來產生控制訊號至背光模組，以控制背光模組。 7 200813975 【實施方式】 在說明書及後續的申請專利範圍當中使用了某些詞 彙來指稱特定的元件。所屬領域中具有通常知識者應可理 解，硬體製造商可能會用不同的名詞來稱呼同一個元件。 本說明書及後續的申請專利範圍並不以名稱的差異來作 為區分元件的方式，而是以元件在功能上的差異來作為區 分的準則。在通篇說明書及後續的請求項當中所提及的 「包含」係為一開放式的用語，故應解釋成「包含但不限 定於」。以外，「耦接」一詞在此係包含任何直接及間接的 電氣連接手段。因此，若文中描述一第一裝置耦接於一第 二裝置，則代表該第一裝置可直接電氣連接於該第二裝 置，或透過其他裝置或連接手段間接地電氣連接至該第二 裝置。 請參照第1圖，其係本發明較佳實施例之顯示裝置之 示意圖。顯示裝置100包含有接收電路110、控制電路 120、顯示單元130以及背光模組140。 接收電路110可利用有線或無線方式來接收類比/數 位格式之輸入訊號，並加以處理而產生影像訊號。影像訊 號包含多個晝面資料（frame)，各晝面資料則包含多個像 素之諸參數值（如亮度值）。對輸入訊號所進行的處理例 如包括：將其從射頻變為中頻（intermediate frequency) 或基頻（base band)的降頻轉換（down-converting)、解 8 200813975 調變動作（demodulating )或當輸入訊號為類比格式時的 轉數位格式處理。 處理後，接收電路110將影像訊號輸出至控制電路 120。控制電路120包含有影像處理電路122、亮度分析電 路124以及背光控制單元126。如第1圖所示，影像處理 電路122耦接接收電路11〇，用以接收影像訊號並對其進 行如解析度調整（scaling )、伽瑪校正（gamma correction )、 内插處理（interpolation)及濾波處理（filtering)等一般 影像處理動作，然後據以產生一驅動訊號至顯示單元 130 °顯示單元130係在驅動訊號之驅動下，依序顯示各 晝面資料而顯示影像訊號之對應内容。 另—方面’亮度分析電路124亦接收影像訊號而對其 =分析動作，以根據各晝面資料之該些像素亮度值來產 生母一晝面資料之亮度分析結果。各晝面資 結果可作為晝面資料間的亮度程度之一比 儿^ 古存八』 。孕又參考。例如， =度:析結果可為—電壓職或H㈣，對於訊號強 度較焉之亮度分析絲，顯示單元13G_„、之書 料時可能便呈現出較高的整體晝面亮度。 心一 ' 背光控制單元12 6耦接亮度分析電路 _ ’並用以根據亮度分析結果來產生4及^核組 組Η0,以控制背光模組⑽提供給號至背光模 ”、、貝7κ早元130之背光 9 200813975 強度。背光模組140包含有兩個MOS電晶體Q1，Q2、變 壓器142、燈管144以及電阻146。兩電晶體Q1及Q2之 閘極皆接收控制訊號。變壓器142之一次侧耦接兩電晶體 Q1，Q2及一輸入電壓Vin，二次侧則耦接一接地端。燈管 144耦接於變壓器142之二次側及電阻146之間，並用以 產生光線射向顯示單元130。 此外，於本實施例中，控制訊號為一脈波寬度調變 (Pulse Width Modulation，PWM)訊號。當 PWM 訊號之 工作週期（duty cycle )改變時，變壓器142二次側之轉換 電壓也會隨之改變，進而改變燈管144之發光亮度。亦即， 可透過控制訊號來調整燈管144之亮度（即背光模組140 之背光大小）。底下茲再附圖詳細說明亮度分析電路124 如何產生亮度分析結果，以供背光控制單元126據以產生 控制訊號。 請參照第2圖，其係亮度分析電路124之示意圖。亮 度分析電路124包含有亮度分類電路210、計算電路220、 亮度指標分析電路230以及記憶單元240。亮度分類電路 210用以接收影像訊號，並將各晝面資料之該些像素之亮 度值區分為數個亮度等級。假設像素亮度值採一般的8位 元設計，即256灰階；於本實施例中，則以每32灰階（ 256/8 ) 作為一亮度等級，而得到8種亮度等級。以其中一晝面資 料為例，亮度分類電路210之區分動作係判斷其所包含之 10 200813975 各像素亮度值落於何種亮度等級中，藉此，對各晝面資料 皆進行上述之區分動作後即可產生一亮度資料。具體而 言，亮度資料能以直方圖（histogram)之方式呈現，如第 3圖所示。 於第3圖中，橫軸代表像素亮度值，且以上述256灰 階為例，由小至大每32灰階區分為一亮度等級，可得8 段相同大小的亮度等級。縱軸則代表某一晝面資料經亮度 分類電路210之區分動作後，所得的落於各亮度等級之像 素數量。例如，第一亮度等級（即區間[〇,31])所對應之 像素數量為PN1，第八亮度等級（即區間[223,255])所對 應之像素數量為PN8，其他第二至第七亮度等級對應之像 素數量分別為PN2〜PN7 (圖未示）。而亮度資料即包含各 畫面資料如第3圖之區分結果。 耦接亮度分類電路210之計算電路220則用以計算亮 度資料，如：統計出各畫面資料之PN1〜PN8的數值或者 計算各晝面資料之一平均亮度值。以第3圖為例，此晝面 資料之平均亮度值avg_LV可如式（1)定義為： avg__LV = (1) iWlxl5：^Ar2x47 + jW3x79 + /W4xlll + iW5xl43 + /W6xl75 + /W7x207 + iW8x239 pm + PN2 + pm + PN 4 + PN 5 + PN 6 + ΡΝΊ + pm 於本實施例中，tf算％路220即將各晝面資料之某一 PNi(卜1〜8)或avg_LV設為其對應之一亮度指標L_index， 11 200813975 L—index即代表對應之晝面資料之一亮度特徵。於其他實 施例中，亮度指標亦可為一組數值，包含PN1〜PN8及 avg—LV 中的數者，如··可定義！^index={pN1，avg_LV}。 接著’計算電路220再將所得的各晝面資料之亮度指標輸 出至亮度指標分析電路230。 亮度指標分析電路230即分析亮度指標以產生各晝面 資料之亮度分析結果。其中，與亮度指標分析電路230耦 接之記憶單元240儲存有若干對應亮度指標之查詢表。視 計算電路220之売度指標定義（可由使用者決定），亮度 指標分析電路230將根據不同的查詢表來產生亮度分析結 果。例如，記憶單元240可儲存三種查詢表L1，L2，及l3， 分別對應免度指標為PNl，PN8j avg LV之情形；亦即， 如使用者決定以PN1作為亮度指標時，亮度指標分析電路 230便讀取記憶單元240中的查詢表L1來進行分析動作。 於其他實施例中，當亮度指標為一組數值時，亮度指標分 析電路230便根據此組數值來讀取對應之查詢表。以 L—index={PNl，avg—LV}為例，亮度指標分析電路23〇便 根據PN1及avg一LV來讀取對應之二維的查詢表。如前述， 亮度分析結果可為一電壓訊號或一電流訊號，對於不同的 壳度指標數值’壳度指標分析電路23()便根據查詢表產生 不同訊號強度之亮度分析結果。 如第1圖所示，背光控制單元126根據亮度分析結果 12 200813975 來控制背光模組140，亦即，背光控制單元126可隨著各 晝面資料之亮度特徵而動態調整背光模組140之背光大 小。底下係以將PN1定義為亮度指標之情形為例，並附圖 說明調整機制。 請參照第4圖，其係亮度指標與背光模組140之背光 亮度的關係圖。橫軸表示的亮度指標即PN1，縱軸代表背 光控制單元126根據由亮度指標PN1所得的亮度分析結 果，而將背光模組140調整至對應的背光亮度。如第4圖 所示，當亮度指標PN1隨著不同的畫面資料而在PNL與 PNH之間變動時，背光模組140之背光亮度將在兩預設值 BL與BH之間以圖示之負相關方式被線性調整至不同大 小。亦即，PN1越大（小），背光模組140之背光亮度將 被調得越低（高）。如某一晝面資料之亮度指標為第4圖 中的PN1時，背光模組140即以亮度為B1之背光來照射 顯示單元130。其中，若PN1大於PNH或小於PNL時， 背光模組140之背光亮度將分別被調整至BL及BH。如此 一來，PN1較大之晝面資料（即亮度低之像素數量多）將 獲得較低之背光亮度而顯示於顯示單元130，PN1較小之 晝面資料（即亮度低之像素數量少）將獲得較高之背光亮 度而顯示於顯示單元130，從而提高顯示單元130顯示影 像訊號時之對比度。當然，於其他實施例中，當採用其他 亮度指標定義或視硬體能力等等考量時’亮度指標與背光 亮度之關係亦可設計成不同於第4圖之線性關係，能以如 13 200813975 曲線關係或類似直方圖之方式來調整。 請參照第5圖，其係依照本發明較佳實施例之亮度控 制方法之流程圖。首先，接收一影像訊號（S510)。如前 述，影像訊號包含多個晝面資料（frame)，各晝面資料則 包含多個像素之諸參數值（如亮度值）。 接著，將各像素之亮度值區分為數個亮度等級，以產 生一亮度資料（S520)。如前述，於本實施例中，像素之 亮度值範圍以〇至255灰階為例，並以由小至大每32灰 階之方式區分出八個亮度等級，而各畫面資料之該些像素 即依亮度值來區分所屬的亮度等級。因此，各晝面資料之 亮度資料能以第3圖之直方圖來表達。 然後，計算亮度資料以產生一亮度指標（S530)。如 前述，亮度指標可為對應任一亮度等級之像素數量，例如 對應第一亮度等級之像素數量PN1 ;或各晝面資料之一平 均亮度值avg—LV (如式（1)之定義）；或包含PN1〜PN8及 avgJLV當中數者的一組數值，如{PN1，PN8}或{PN1， avg—LV} 〇 接著，分析亮度指標以產生一亮度分析結果（S540)。 如前述，視亮度指標的定義方式可根據適當之查詢表來產 生亮度分析結果。 14 200813975 最後，根據亮度分析結果來調整背光模組之背光 (S550)。如前述，視亮度指標之定義方式以及硬體運算 能力等實際應用考量，能以各種調整機制來控制背光模 組。例如，如第4圖所示之線性關係，或其他非線性方式。 藉此，隨著不同的畫面資料（亮度分析結果），背光模組 之背光亮度將可被動態調整至對應之適當大小，而有效提 升影像訊號呈現出之影像品質。 以上所述僅為本發明之較佳實施例，凡依本發明申請 專利範圍所做之均等變化與修飾，皆應屬本發明之涵蓋範 圍。 【圖式簡单說明】 第1圖係本發明較佳實施例之顯示裝置之示意圖。 第2圖係亮度分析電路124之示意圖。 第3圖係代表亮度資料之直方圖。 第4圖係亮度指標與背光模組140之背光亮度的關係圖。 第5圖係依照本發明較佳實施例之亮度控制方法之流程圖。 【主要元件符號說明】 100顯示裝置 110接收電路 120控制電路 122影像處理電路 15 200813975 124亮度分析電路 126背光控制單元 130顯示單元 140背光模組 142變壓器 144燈管 146電阻 210亮度分類電路 220計算電路 230亮度指標分析電路 240記憶單元200813975 IX. Description of the Invention: [Technical Field] The present invention relates to a display device and a brightness control method thereof, and more particularly to a display device for controlling a backlight module based on brightness analysis results of image signals and brightness control thereof method. [Prior Art] Among the many factors that determine the quality of display quality, the contrast value is a key factor, especially for liquid crystal display (LcD). The 'such as the characteristics of the liquid crystal display panel, the image signal quality or the liquid crystal display panel m, etc.' can affect the contrast value. Therefore, the industry has long been actively seeking ways to improve the comparison of displays, and several related technologies have also been developed. However, traditional technology has not effectively strengthened the comparison value. SUMMARY OF THE INVENTION The main purpose of the present invention is to provide a display device for controlling a backlight module according to the brightness analysis result of the image signal and a brightness control method thereof. The present invention discloses a display device including a receiving circuit and image processing. Road, display unit, brightness analysis circuit, backlight and backlight control unit. The receiving circuit is configured to process the received input signal to generate an image signal. The image processing circuit _ receiving circuit is used to process the video signal 200813975 to generate a driving signal. The display unit is coupled to the image processing circuit and displays the corresponding content of the image signal driven by the driving signal. The brightness analysis circuit is coupled to the receiving circuit and used to analyze the image signal to generate a brightness analysis result. The backlight module is used to provide the backlight required by the display unit. The backlight control unit is coupled to the brightness analysis circuit and the backlight module, and is configured to generate a control signal to the backlight module according to the brightness analysis result to control the backlight module. The invention further discloses a control circuit for controlling a display unit and a backlight module, and the backlight module is used for providing a backlight required by the display unit. The control circuit includes an image processing circuit, a brightness analysis circuit, and a backlight control unit. The image processing circuit is configured to receive and process an image signal including a plurality of facets, and the display unit is configured to display the facet data. The brightness analysis circuit is configured to receive the image signal and analyze the brightness value of the image signal to generate a brightness analysis result. The backlight control unit is coupled to the brightness analysis circuit for generating a control signal to the backlight module according to the brightness analysis result to control the backlight module. The present invention further discloses a brightness control method for a display device. The display device includes a display unit and a backlight module. The method controls the display unit to display the corresponding content of the image signal, and controls the backlight module to be provided to the display unit. Backlighting. The method comprises: (a) processing the image signal to generate a driving signal to drive the display unit; (b) displaying the corresponding content of the image signal; (c) analyzing the image signal to generate a brightness analysis result; and (d) according to the brightness The result of the analysis is to generate a control signal to the backlight module to control the backlight module. 7 200813975 [Embodiment] Certain terms are used in the specification and subsequent claims to refer to specific elements. Those of ordinary skill in the art should understand that a hardware manufacturer may refer to the same component by a different noun. The scope of this specification and the subsequent patent application do not use the difference in name as the means of distinguishing the elements, but the difference in function of the elements as the criterion for the distinction. The "contains" mentioned in the overall specification and subsequent claims are an open term and should be interpreted as "including but not limited to". In addition, the term "coupled" is used herein to include any direct and indirect electrical connection. Thus, if a first device is coupled to a second device, it is meant that the first device can be directly electrically coupled to the second device or indirectly electrically coupled to the second device through other devices or connection means. Please refer to Fig. 1, which is a schematic view of a display device in accordance with a preferred embodiment of the present invention. The display device 100 includes a receiving circuit 110, a control circuit 120, a display unit 130, and a backlight module 140. The receiving circuit 110 can receive the input signal in the analog/digital format by wire or wirelessly and process it to generate an image signal. The image signal contains a plurality of facets, and each facet data contains parameter values (such as brightness values) of a plurality of pixels. The processing performed on the input signal includes, for example, down-converting from radio frequency to intermediate frequency or base band, solution 8 200813975 modulation (demodulating) or when The conversion format is processed when the input signal is in the analog format. After processing, the receiving circuit 110 outputs the image signal to the control circuit 120. The control circuit 120 includes an image processing circuit 122, a brightness analysis circuit 124, and a backlight control unit 126. As shown in FIG. 1, the image processing circuit 122 is coupled to the receiving circuit 11 for receiving image signals and performing scaling, gamma correction, interpolation, and A general image processing operation such as filtering is performed, and then a driving signal is generated to the display unit 130. The display unit 130 is driven by the driving signal to sequentially display each side of the data to display the corresponding content of the image signal. In another aspect, the brightness analysis circuit 124 receives the image signal and performs an analysis operation to generate a brightness analysis result of the parent side data based on the pixel brightness values of the respective face data. The results of each face can be used as one of the brightness levels of the facet data. Pregnancy and reference. For example, = degree: the result of the analysis can be - voltage or H (four), for the brightness analysis of the signal intensity, the display unit 13G_„, the book material may show a higher overall brightness of the face. The control unit 12 6 is coupled to the brightness analysis circuit _′ and is configured to generate a 4 and a core group Η0 according to the brightness analysis result, so as to control the backlight module (10) to provide a signal to the backlight mode”, and the backlight of the 7 κ early element 130 200813975 Strength. The backlight module 140 includes two MOS transistors Q1, Q2, a transformer 142, a lamp 144, and a resistor 146. The gates of both transistors Q1 and Q2 receive control signals. The primary side of the transformer 142 is coupled to the two transistors Q1, Q2 and an input voltage Vin, and the secondary side is coupled to a ground terminal. The light tube 144 is coupled between the secondary side of the transformer 142 and the resistor 146, and is used to generate light to the display unit 130. In addition, in this embodiment, the control signal is a Pulse Width Modulation (PWM) signal. When the duty cycle of the PWM signal changes, the switching voltage of the secondary side of the transformer 142 also changes, thereby changing the luminance of the lamp 144. That is, the brightness of the lamp 144 (ie, the backlight size of the backlight module 140) can be adjusted by the control signal. The following figure details how the brightness analysis circuit 124 produces a brightness analysis result for the backlight control unit 126 to generate a control signal. Please refer to FIG. 2, which is a schematic diagram of the brightness analysis circuit 124. The brightness analysis circuit 124 includes a brightness classification circuit 210, a calculation circuit 220, a brightness indicator analysis circuit 230, and a memory unit 240. The brightness classification circuit 210 is configured to receive the image signal and divide the brightness values of the pixels of each of the face data into a plurality of brightness levels. It is assumed that the pixel luminance value adopts a general 8-bit design, that is, 256 gray scales; in this embodiment, each of the 32 gray scales (256/8) is used as a luminance level, and eight luminance levels are obtained. Taking one of the face data as an example, the distinguishing action of the brightness classifying circuit 210 determines which brightness level the pixel brightness value of each of the 10, 2008, and 13 pixels included in the brightness is included in the brightness level, thereby performing the above-mentioned distinguishing action on each facet data. A brightness data can be generated. Specifically, the brightness data can be presented in the form of a histogram, as shown in Figure 3. In Fig. 3, the horizontal axis represents the pixel luminance value, and the above-mentioned 256 gray scale is taken as an example, and each of the 32 gray scales is divided into a brightness level from small to large, and 8 segments of the same size brightness level can be obtained. The vertical axis represents the number of pixels that fall within each brightness level after a certain facet data is distinguished by the brightness classification circuit 210. For example, the number of pixels corresponding to the first brightness level (ie, interval [〇, 31]) is PN1, and the number of pixels corresponding to the eighth brightness level (ie, interval [223, 255]) is PN8, and other second to seventh brightness levels. The corresponding number of pixels is PN2~PN7 (not shown). The brightness data contains the results of each screen data as shown in Figure 3. The calculation circuit 220 coupled to the brightness classification circuit 210 is configured to calculate brightness data, such as: counting the values of PN1 to PN8 of each picture data or calculating an average brightness value of each of the face data. Taking Figure 3 as an example, the average brightness value avg_LV of this facet data can be defined as: (v): avg__LV = (1) iWlxl5:^Ar2x47 + jW3x79 + /W4xlll + iW5xl43 + /W6xl75 + /W7x207 + iW8x239 pm + PN2 + pm + PN 4 + PN 5 + PN 6 + ΡΝΊ + pm In this embodiment, the tf calculation % path 220 sets a certain PNi (Bu 1~8) or avg_LV of each side data to its corresponding A brightness index L_index, 11 200813975 L—index represents the brightness characteristic of one of the corresponding side data. In other embodiments, the brightness indicator can also be a set of values, including the number of PN1~PN8 and avg-LV, as defined by! ^index={pN1, avg_LV}. Then, the calculation circuit 220 outputs the obtained brightness index of each facet data to the brightness indicator analysis circuit 230. The brightness indicator analysis circuit 230 analyzes the brightness indicator to generate a brightness analysis result for each facet data. The memory unit 240 coupled to the brightness indicator analysis circuit 230 stores a plurality of lookup tables corresponding to the brightness indicators. Depending on the parameter definition of the calculation circuit 220 (which can be determined by the user), the brightness indicator analysis circuit 230 will generate a brightness analysis result based on different lookup tables. For example, the memory unit 240 can store three look-up tables L1, L2, and l3, respectively, corresponding to the case where the degree of exemption index is PN1, PN8j avg LV; that is, if the user decides to use PN1 as the brightness index, the brightness indicator analyzing circuit 230 The lookup table L1 in the memory unit 240 is read to perform an analysis operation. In other embodiments, when the brightness indicator is a set of values, the brightness indicator analysis circuit 230 reads the corresponding lookup table based on the set of values. Taking L-index={PNl, avg-LV} as an example, the brightness index analysis circuit 23 reads the corresponding two-dimensional lookup table according to PN1 and avg-LV. As described above, the brightness analysis result may be a voltage signal or a current signal. For different shell index values, the shell index analysis circuit 23() generates brightness analysis results of different signal intensities according to the lookup table. As shown in FIG. 1 , the backlight control unit 126 controls the backlight module 140 according to the brightness analysis result 12 200813975. That is, the backlight control unit 126 can dynamically adjust the backlight of the backlight module 140 according to the brightness characteristics of each facet data. size. The case where PN1 is defined as a brightness index is taken as an example, and the adjustment mechanism is illustrated in the drawings. Please refer to FIG. 4, which is a relationship diagram between the brightness index and the backlight brightness of the backlight module 140. The luminance index indicated by the horizontal axis is PN1, and the vertical axis represents the backlight control unit 126 adjusts the backlight module 140 to the corresponding backlight luminance based on the luminance analysis result obtained from the luminance index PN1. As shown in FIG. 4, when the brightness index PN1 varies between PNL and PNH with different picture data, the backlight brightness of the backlight module 140 will be negative between the two preset values BL and BH. The correlation is linearly adjusted to different sizes. That is, the larger (small) PN1, the lower the backlight brightness of the backlight module 140 will be adjusted (high). If the brightness index of a certain facet data is PN1 in Fig. 4, the backlight module 140 illuminates the display unit 130 with a backlight having a brightness of B1. Wherein, if PN1 is greater than PNH or smaller than PNL, the backlight brightness of the backlight module 140 will be adjusted to BL and BH, respectively. In this way, the larger PN1 data (ie, the number of pixels with low brightness) will obtain a lower backlight brightness and be displayed on the display unit 130, and the smaller PN1 data (ie, the number of pixels with low brightness) is small. A higher backlight brightness will be obtained and displayed on the display unit 130, thereby improving the contrast of the display unit 130 when displaying the image signal. Of course, in other embodiments, when other brightness index definitions or hardware capabilities are taken into consideration, the relationship between the brightness index and the backlight brightness can also be designed to be different from the linear relationship of FIG. 4, which can be as a curve as 13 200813975. A relationship or a similar histogram is used to adjust. Referring to Figure 5, there is shown a flow chart of a brightness control method in accordance with a preferred embodiment of the present invention. First, an image signal is received (S510). As mentioned above, the image signal contains a plurality of frame data, and each of the face data includes parameter values (such as brightness values) of a plurality of pixels. Next, the luminance values of the respective pixels are divided into a plurality of luminance levels to generate a luminance data (S520). As described above, in the embodiment, the luminance value range of the pixel is exemplified by 〇 to 255 gray scale, and eight brightness levels are distinguished by a small to large gray scale, and the pixels of each picture data are used. That is, the brightness level is distinguished according to the brightness value. Therefore, the brightness data of each facet data can be expressed by the histogram of Fig. 3. Then, the brightness data is calculated to generate a brightness indicator (S530). As described above, the brightness indicator may be the number of pixels corresponding to any brightness level, for example, the number of pixels corresponding to the first brightness level PN1; or the average brightness value of each of the face data avg-LV (as defined by equation (1)); Or a set of values including PN1 to PN8 and avgJLV, such as {PN1, PN8} or {PN1, avg-LV} Next, the luminance index is analyzed to generate a luminance analysis result (S540). As described above, the brightness indicator can be defined in a manner that produces a brightness analysis result based on an appropriate lookup table. 14 200813975 Finally, the backlight of the backlight module (S550) is adjusted according to the brightness analysis result. As described above, depending on the actual application considerations such as the definition of the brightness index and the hardware computing power, the backlight module can be controlled by various adjustment mechanisms. For example, a linear relationship as shown in Figure 4, or other non-linear approach. Therefore, with different picture data (luminance analysis results), the backlight brightness of the backlight module can be dynamically adjusted to a correspondingly appropriate size, thereby effectively improving the image quality of the image signal. The above are only the preferred embodiments of the present invention, and all changes and modifications made to the scope of the invention are intended to be included in the scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic view of a display device in accordance with a preferred embodiment of the present invention. FIG. 2 is a schematic diagram of the brightness analysis circuit 124. Figure 3 is a histogram representing the luminance data. FIG. 4 is a graph showing the relationship between the brightness index and the backlight brightness of the backlight module 140. Figure 5 is a flow chart of a brightness control method in accordance with a preferred embodiment of the present invention. [Main component symbol description] 100 display device 110 receiving circuit 120 control circuit 122 image processing circuit 15 200813975 124 brightness analysis circuit 126 backlight control unit 130 display unit 140 backlight module 142 transformer 144 lamp 146 resistance 210 brightness classification circuit 220 calculation circuit 230 brightness indicator analysis circuit 240 memory unit
Ql、Q2 MOS電晶體 16Ql, Q2 MOS transistor 16