200527114 九、發明說明： 【發明所屬之技術領域】 本發明係關於液晶顯示投影系統，具體而言，本發明係 關於液晶顯示投影系統中之亮度調整。 【先前技術】 液晶（LC)技術已應用在投影電影中使用的投影顯示号、 電腦監視器、銷售點顯示器及電子電影，此處提出少數應 用。 一項最新LC裝置應用是在石夕基板上的反射型lc顯示 器，用以構成一種矽液晶（liquid crystal on silicon ; LCQy 結構。矽反射型LC顯示器通常包括一由互補金屬氧化物半 導體（C Μ Ο S)電晶體/切換器組成的主動式矩陣陣列，彼等電 曰曰體/切換器係用於選擇性旋轉液晶分子轴線。眾所周知， 藉由跨LC胞施加電壓，就可以控制LC分子方向，並且選擇 性變更反射光的偏光狀態。以此方式，藉由選擇性切換陣 列中的電晶體，就可以使用LC媒體來配合影像資訊調變光 線。接著’藉由偏光和投影光學就可以將已調變之光成影 於螢幕上，藉此形成影像或「圖像」。 在命多LCD糸統中’會先將來自於光源的光線選擇性往 特定方向偏光，之後才會入射在LC層上。該LC層可具有一 選擇性施加的電壓，藉此以某方式來確定材料分子的方 位。接著，在光線穿過該LC層行進過程中，選擇性改變要 入射在LC層上之光線的光偏振。 LCD系統通常包括一偏振分光器（pBS)。lcd所反射且具 98161.doc 200527114 有某偏光狀態之光線將從PBS反射或穿透PBS(視系統結構 而定），並且接著入射在投影光學元件上。此光線形成影像 的党態像素。反之，垂直於亮態像素的偏振光被阻止抵達 光學元件，並且變成暗態光。在此方式中，可以由複數個 亮態像素與暗態像素來形成一影像，而藉由捲動輸入訊號 至LCD中的電晶體矩陣，就可以形成一捲動影像。 已知的LCD顯示系統之對比度較不理想。這是因為最暗 度係由偏光器的光洩漏所決定。這也可能起因於非理想之 分子方位分佈而造成液晶層中的殘餘雙折射，以及起因於 個別偏光相依型部件之光學轴錯位。另外，當影像是暗影 像時，因為設定了最暗度，所以會由於幾乎看不見任何細 節而無法接受所形成之影像的對比。最後，已知的LCD顯 示系統可採用偏光器或其它阻滯器（retarder)，藉由增強對 比或視角相依性來改良圖像效果。然而，這些元件最終會 由於隨時間過熱導致材料降級而變成無效率。 【發明内容】 根據一項示範性具體實施例，一種LCD顯示器包括一光 源及一佈置在該光源與一偏振分光器（pBS)之間的]^(：：1)亮 度調整裝置。 根據本發明另一項示範性具體實施例，一種在Lcd顯示 裝置螢幕上形成一高對比但較暗影像之方法，其包括：在 光源與一偏振分光器（PBS)之間提供一 LCD亮度調整農 置；以及選擇性改變該LCD亮度調整裝置中液晶分子之分 子方位。選擇性改變液晶分子方位會影響往其餘光路徑反 98161.doc 200527114 射離開LCD面板之LCD亮度調整輸出的偏光向量，因此降 低正照明系統矩陣顯示面板之光的強度。結果，可通過總 光路徑的光量被減少，這會減少抵達觀看者眼睛的光量。 從下文中參考附圖解說的詳細說明可更加瞭解本發明。 應注意’附圖各項特徵不需要按比例繪製。實際上，可能 會任意放大或縮小尺寸，以利於說明更清楚。 【實施方式】 基於解說而非限制之目的，在下文的詳細說明中提出用 以揭示特定細節的示範性具體實施例，以便充分認識示範 性具體實施例。然而，熟悉此項技術且得益於此份說明書 的人士應清楚知道，不運用本文揭示之特定細節的其它具 體實施例。另外，可省略熟知之裝置、電路及方法的說明， 以防混淆本發明的說明。最後，相似的參考數字代表相似 的零件。 簡言之，示範性具體實施例係關於一種用於在lcd顯示 裝置之顯示幕上選擇性提供暗（有時候稱為「低光度」）且高 對對比影像之方法及設備。作為例證說明，一種LCD亮度 調整裝置選擇性改變其所發出之垂直偏光向量的量值，促 使衫像強度被選擇性改變成一所要的強度。隨著本份說明 書繼續將會更加明白，因為在顯示_暗影像過程中，該L⑶ 亮度調整裝置會降低LCD面板上光線的發光度，所以對比 j維持在=相對高對比度。以此方式，#不需要最大可獲 传之系統亮度時，會降低所顯示之影像内最暗像素的強度。 圖1繪示根據示範性具體實施例之LCD投影顯示裝又置 9816l.doc 200527114 (LCD顯示器）100 〇請注意，該LCD投影顯示裝置100可被併 入一前顯示裝置中。該L C D顯示器1 〇 〇包括一照明系統（或 照明單元）101，照明系統可能是放電氣體型光源（例如，高 壓水銀燈、惰性氣體弧光燈或il化金屬燈）、LED陣列或用 以發射顯示裝置中使用之含紅綠藍（R，G，B)光之光線的其它 已知光源。另外，該照明系統101可包括一抛物線狀鏡或類 似裝置。 該LCD顯示器100可包括用於LCD成像的各種熟知元 件。來自照明系統1 〇 1的光線穿過用於使光束成形之一組光 束成开> 光學元件102-103，促使以矩形且同質分佈的光束來 照射顯示器。接著，來自光束成形光學元件103的光線入射 在一偏光轉換系統（PCS) 104上。該處理序將該照明系統1〇1 所發射之無偏振光線轉換成一已偏振光束，而不會有大光 損失。作為例證說明，該PCS1{)4包括反射型偏振分光光學 元件(例如，-組偏振分光器)’用於藉由將光束某偏振模式 反射成除其它偏振模式以外的另一方向來分割該光束之偏 振模式。在該PCS 104中的某些位置，按幾何學原理分離兩 ，正父偏振模式，促使可使用偏振旋轉元件將該等兩種模 式之一轉換成相反模式。 έ月注思，元件101_104皆為 a ,,、a ......u〜π仪w芩尸/r热知，並 規明。711件及其功能的詳細描述，以防混淆本發明 美料利宏°，彼等元件的詳細描述可參閱—地等人 文〜國專利案軸，。93,該案内容以引用方式明確併入 98l6l.doc 200527114 從PCS 104發射的光線入射在一中繼透鏡1〇8上，並且被 一反射表面10 9 (圖中繚示為一鏡子）予以反射。光線入射在 一第二中繼透鏡110上，接著行進穿過一 LCD亮度調整器 111 (圖中繪示為一透射型LCD面板）。在行進穿過該LCD亮 度調整器111後，光線入射在一偏振分光器（PBS) 112上。隨 著本份說明書繼續將會更加明白，該LCD亮度調整器1丨丨及 5亥PBS 112係用來控制入射在顯示面板115-117上之光線的 強度，並且因此設定能夠抵達投影透鏡113之光線及所顯示 之影像的最大強度。 適當偏振的光線直接行進穿過該PBS 112,並且入射在由 棱鏡元件所組成的棱鏡系統114上，用以將紅光導引至一紅 色液aa面板1 1 5、一綠色液晶面板1 1 6及一藍色液晶面板 117。藉由對應面板115-117予以調變後，光線被透射至該 PBS 112，用以按偏振狀態來分離光線，並且每種顏色之亮 態光線（亮態像素）被該PBS 112反射而朝向該投影透鏡 Π3。暗態光線（暗態像素）的偏振狀態正交於朝向該投影透 鏡113之反射光線的偏振狀態，暗態光線（暗態像素）係往遠 離該投影透鏡113方向予以透射。在此方式中，暗態光線與 亮態光線在顯示幕（圖中未繪示）上形成影像。 如上文所述，該LCD亮度調整器111有助於降低顯示幕上 「暗」影像（例如，夜間錄影或相片）的整體發光度。在已知 系統中，當顯示暗相片或錄影場景時會有顯著的問題。例 如，在已知系統中，此項降低發光度同等於僅降低亮態光 線的光度。為此目的，在已知系統中，最暗像素會維持其 98161.doc 200527114 強度，而與影像内容無關。換言之，暗影像與亮影像的最 暗像素皆相同。於是，在暗影像中，介於最亮像素與最暗 像素之間的對比不佳，並且在某情況下，影像呈現出難以 識別。示範性具體實施例解決已知裝置的這些和其它缺點。 該LCD亮度調整器111是一種用於選擇性改變穿過該亮 度調整器之光線的偏振狀態之LCD裝置（單元）。在一項示範 性具體實施例中，該亮度調整器是一 9〇。扭轉向列單元，但 是可依據顯示架構來使用其它LCD裝置。請注意，在一項 示範性具體實施例中，該LCD亮度調整器lu可與該pcs 104構成一整體。 雖然90。扭轉向列單元對製造商極為有益且容易，並且最 常有效運用在LCD中，但是可使用其它裝置來當做亮度調 正器。例如，顯示系統可由一使用紅綠藍閃光時間相繼照 射的單一面板所組成。在一項示範性具體實施例中，由於 鐵電顯示效應較為快速，並且可個別完成紅綠藍閃光之對 比最佳化，所以實施鐵電單元會有所助益。 在另一項示範性具體實施例中，該亮度調整器可能是一 種長1 供電控雙折射（Electrical Controlled Birefringence ; ECB)政應的裝置。ECB效應的優點為：可藉由LCD層上的 電壓來控制ECB單元的光譜輸出；並且可依據用以呈現影 像之紅綠藍的最大必要光強度來調整亮度調整效應。 無論如何’藉由該亮度調整器Π1所改變的偏振被用來選 擇性防止一特定偏振狀態之光線被傳送至該棱鏡系統 Π4。這會在顯示幕上形成暗影像。或者，該lcd亮度調整 98161.doc 200527114 器可不改變入射在其上的光線，並且整個光線被透射至該 棱鏡系統114。這會在顯示幕上形成高強度或常態影像。最 後’光線可被以橢圓形予以偏振，促使光線具有被PBS U2 所透射的向量分量，並且該PBS 112將彼等分量往相反於該 投影透鏡113的方向反射。在此情況下，所形成的影像是螢 幕上的中等亮度影像。 請注意，在彼等及其它具體實施例中，一偏光器（例如， 圖5所示之偏光器518)可被佈置在該lcd亮度調整器111與 該PBS 112之間。假使入射在Lcd亮度調整器上之光線的偏 振狀態品質不足時，就可以使用此偏光器（例如，在暗態亮 度调整器中’亮度調整器之光輸出的光譜分佈會由於照明 系統中光學部件中的雙折射問題而變成有色）。該額外偏光 器將有效地吸收光束中的非純光。作為例證說明，該偏光 器是一反射型偏光器，例如：干涉塗膜偏光器；Brewster 片；雙折射層；全像元件；或栅線偏光器（wire grid polarizer) 〇 在此項及額外具體實施例中，LCD亮度調整裝置可包括 一雙折射補償層，用以實質上最佳化光束行進通過該LCD 亮度調整器111之主方向中之該LCD亮度調整器111的對 比。 圖2繪示圖1所示之LCD顯示系統1〇〇中之該LcD亮度調 整器處於咼強度輸出模式的圖式。在此示範性具體實施例 中，該乙0〇壳度調整器Hi的液晶分子方位，促使*RGB光 105-107(圖中標示為201)所組成之光線的輸入偏振向量2〇2 98161.doc -11 - 200527114 在’、貝上不叉影響情況下行進穿過該LCD亮度調整器 111以此方式，輸出偏振向量203相對於該輸入偏振向量 而了實：上不變更。在此示範性具體實施例中，該咖亮 度調整器111實質上不會影響行進穿過該亮度調整器之光 線的偏振狀態。即，在方向205，該PBS 112反射、約僅1%光 線。 接著，具有偏振狀態2〇3之發射光線（圖中概念上繪示為 204)入射在該pBS 112上並且實際上經由該pBs ιΐ2完全透 射，在此階段實際上無任何光線往方向2〇5反射。如上文所 述，此光線204行進穿過該棱鏡系統114且被調變成用於影 像成形的暗態像素（在此階段方向2〇5反射）及暗態像素（反 射至投影透鏡113)。顯而易見，在將開啟狀態電壓施加至 作為例證說明之LCD的狀態中，至投影透鏡的輸出在顯示 幕上形成一亮態或常態亮度影像。 圖3繪示圖1所示之LCD投影顯示器處於低強度輸出狀 悲’藉此在顯示幕上形成一暗影像。在圖3所示之示範性具 體實施例中，該LCD亮度調整器的液晶材料分子方位，促 使具有某方向入射偏振之光線會從具有正交於輸入偏振向 ϊ之偏振向量的LCD亮度調整器發出。例如，在此示範性 具體實施例中，入射光線105-107 (圖中概念上繪示為3〇1) 具有繪不為向量3 02的輸入偏振狀態（Pin)。在行進穿過該 LCD亮度調整器111後，實質上所有光線的偏振狀態被旋轉 90°，並且從具有繪示為向量303之輸出偏振狀態（pQut)的 LCD亮度調整器發出。 98161.doc -12- 200527114 連同從具有正交於該PBS 112透射軸之偏振狀態的該 LCD亮度調整器1 π所發射之光線的一實質部分，實際上所 有光線301往方向304 (相反於該投影透鏡113的方向）反 射。另外，僅該光線3 01之一小部分（約1 %級數）會從具有對 齊該PBS 112透射軸之偏振狀態的該LCD亮度調整器111發 射。此光線（圖中概念上繪示為305)入射在該棱鏡系統 上，藉此由該等LC面板115-117予以調變。 如上文所述，依據該等LC面板115-117的作用，傳回至該 PBS 112的光線被反射而朝向該投影透鏡113或方向3〇4，若 反射朝向該投影透鏡113，則為最亮狀態；若反射朝向方向 304，則為最暗狀態。但是，在無該LCD亮度調整器之作用 情況下，由該等LC面板115-117所調變之光線305表示將透 射至該投影透鏡113或往方向304之光線的一小部分。在一 項示範性具體實施例中，包括一光線俘獲器（light trap)，用 以吸收介於該LCD亮度調整器與該等LC面板之間的PBS所 反射的光線。 在此等示範性具體實施例中，該LCD亮度調整器111會降 低至該等LC面板之光線的整體強度，最暗像素會變成較 暗，並且以目前所描述之方式，對比相較於已知裝置有所 改進。如上文所述’在已知LCD型顯示裝置中，黑態光線 控制受限於偏光器的能力及液晶電光效應。偏光器、LC材 料及對位並不理想’並且預定防止抵達顯示幕之部分光線 會穿越而洩漏。就其本身而論，在已知系統中，無關於亮 度’最暗像素的強度基本上在怪定強度。這解釋為，當所 98161.doc -13- 200527114 顯示之影像沒有任何像素處於最大亮度時，則影像的對比 降低例如，如果LCD面板可提供ίου對比，並且正在顯 示之影像具有5〇%光線輸出最亮程度（或最大值的5〇%，稱 為50%最大值）的最亮像素，則會據此來驅動lcd。然而， 當最亮像素處於50%最大值時，最暗像素仍然處於1%最大 值，亚且所顯示之影像的對比降低至僅5〇:丨。假使最亮像 素處於5%最大值時，最暗像素維持在1%最大值，則所顯示 之影像中達成的對比更下降至僅5:1。顯而易見，在非低低 光度影像中，已知LCD系統中的對比太低而無法接受，並 且會損失影像申的所有細節。 但是，根據本文中所描述之示範性具體實施例，最亮像 素的強度受控於該LCD亮度調整器，並且不受控於該等 面板（例如，115-117)。這意謂著在光線抵達該等£c面板之 前會先降低光線的強度。假使影像中的最亮像素為5〇%; 該壳度調整器將至LCD上之光線的發光度調整為5〇% ;這也 會使該顯示之影像中最暗像素的強度降低5〇%。這導致最 亮像素處於50%最大值時，而現在最暗像素被降低至僅 〇·5%最大值，導致所顯示之影像的對比為ι〇〇··ι。在此特定 實例中所達成之景》像的對比是相對於已知方法及設備的 兩倍。 在最亮像素為5〇/。最大值之第二種案例中；該亮度調整器 將至LCD上之光線的發光度調整為5%最大值；並且該亮度 調整器也將最暗像素調整為95%最大值。這導致最亮像素 處於5/。最大值日守，而現在最暗像素被降低至僅〇 最大 98161.doc -14- 200527114 值’導致所顯示之影像的對比再次為100:1。在此特定實例 中’所達成之影像的對比改良成為相對於已知設備及方法 的20倍。 此不範性具體實施例另一項有用態樣係關於對比比率關 於視角的相依性。眾所周知，當以非LCD平面法線之〇。度 的角度觀看LCD影像時，就會影響對比。但是，因為不是 直接觀看本文所描述之例證性具體實施例的LCD亮度調整 器’所以在此方式中不會不利地影響對比。 圖4繪示根據一項示範性具體實施例，圖丨所示之 不系統100中之該LCD亮度調整器處於中等強度輸出模式 的圖式。眾所周知，液晶材料的電光效應取決於施加至液 晶的電壓。例如，光透射相對於90度扭轉向列LCD面板之 電壓係隨著施加之電壓而急劇降低。就其本身而論，藉由 軛加相對應於所要之位準的電壓，就可以將透射度降低至 所選擇的程度，且因而將亮度降低至所選擇的程度。 忒LCD壳度調整器U1還可以被用於使亮度在一高亮度 (例如，圖2所不之示範性具體實施例）與低亮度（例如，圖3 所示之不範性具體實施例）之間持續變化。在圖4所示之示 範性具體實施例中，該LCD亮度調整器的液晶材料分子方 位，促使具有入射線性偏振之光線會從具有橢圓形偏振光 線的LCD冗度凋整為發出；即，具有平行且垂直於輸入偏 振狀怨之偏振向量分量的光線。例如，在此示範性具體實 施例中，入射光線105-107 (圖中概念上繪示為4〇1)具有繪 示為向量402的輸入偏振狀態（Ριη)。在行進穿過該lcd亮度 98161.doc -15- 200527114 調整器111後，光線具有如圖所示之橢圓形狀態的偏振狀態 (Pout) 403。 請注意，在此示範性具體實施例中，1>_實質上係以圓形 予以偏振，這意謂著平行於輸入偏振向量4〇2之p。^偏振向 量分量的量值等於垂直於輸入偏振向量4〇2之匕^偏振向量 分置的ϊ值。但是，顯而易見，藉由選擇施加至LCD亮度 調整器的其它電壓，就可以選用其它的橢圓狀態。 在參考圖4所描述之示範性具體實施例中，連同從具有正 父於忒PBS 112透射轴之偏振狀態的該LCD亮度調整器j J j 所發射之約二分之一光能量，實際上約5〇%光線4〇1往方向 4 0 4 (相反於e亥投影透鏡113的方向）反射。另外，僅約$ 〇 % 光線401會從具有對齊該PBS 112透射軸之偏振狀態的該 LCD亮度調整器發射。此光線（圖中概念上繪示為4〇5) 入射在該棱鏡系統114上，藉此由LC面板115-117予以調變。 如上文所述’依據該等LC面板11 5-117中個別像素的作 用，從彼等像素傳回至該PBS 112的光線被反射而朝向該投 影透鏡11 3或方向404，若反射朝向該投影透鏡丨丨3，則為亮 態像素；若反射朝向方向404，則為暗態像素。 圖5繪示根據示範性具體實施例之[CD投影顯示器50〇。 該LCD顯示器500具有前文參考圖ι-4之示範性具體實施例 所描述的示範性具體實施例特徵。據此，在相關的詳細說 明中’將不重複描述這些共同的特徵。 邊顯示器500是一包括照明源5〇 1之捲動式彩色顯示裝 置’遠照明源5 01包含一抛物面反射器及一發光元件，如上 98161.doc -16- 200527114 文所述之元件。來自照明單元501的光線穿過用於使光束成 形之一組光束成形光學元件502_503，促使以矩形且同質分 佈的光束來照射顯示器。接著，來自光束成形光學元件5〇3 的光線入射在一偏光轉換系統（1>(：^) 504上。該處理序將該 照明系統101所發射之無偏振光線轉換成一已偏振光束，而 不會有顯著的光能量損失。 孩顯示裔還包括波長選擇鏡5 0 5，其可能是物理光學所熟 知的介電堆疊型反射器或二色性鏡。彼等波長選擇鏡將反 射某波長之光線（例如，紅光506)，並且透射所有其它波長 (例如，藍光和綠光507)。 沿彼等線繼續，綠光508被反射且藍光509被透射，如圖 所示。旋轉式棱鏡5 10係用來以此項技術所熟知方式來掃描 影像’並且鏡5 11和透鏡5 12有助於視需要目苗準及聚焦光 線。最後，波長選擇鏡5 13的作用方式及類型相同於波長選 擇鏡505的作用方式及類型；但是，鏡513係用來重組至pbs 5 14的光線。PBS 5 14以已知方式作用以將光線導引至lc面 板515 (圖中繪示為LCOS面板），並且將已調變光線導引至 投影光學元件5 16。由於彼等各種元件之作用已為吾人所熟 知，所以在相關詳細說明中將省略其進一步說明。最後， 請注意，配合此項示範性具體實施例所描述之特徵及其它 特徵和說明可參閱Janssen等人的美國專利第6,563,551號。 該專利内容以引用方式明確併入本文中。 一 L C D亮度調整器5 1 7被插入在該照明源5 〇 1與該p b s 5 14之間。該LCD亮度調整器517有助於控制在顯示幕（圖中 98161.doc 17 200527114200527114 IX. Description of the invention: [Technical field to which the invention belongs] The present invention relates to a liquid crystal display projection system. Specifically, the present invention relates to brightness adjustment in a liquid crystal display projection system. [Previous Technology] Liquid crystal (LC) technology has been applied to projection display numbers, computer monitors, point-of-sale displays, and electronic movies used in projection movies, and a few applications are proposed here. One of the latest LC device applications is a reflective LCD display on a Shi Xi substrate to form a liquid crystal on silicon (LCQy) structure. Silicon reflective LC displays typically include a complementary metal oxide semiconductor (CM) 〇 S) Active matrix arrays composed of transistors / switchers, which are used to selectively rotate the axis of liquid crystal molecules. It is well known that LC molecules can be controlled by applying a voltage across the LC cell Direction, and selectively change the polarization state of the reflected light. In this way, by selectively switching the transistors in the array, LC media can be used to adjust the light in accordance with the image information. Then, 'polarization and projection optics can be used. The modulated light is reflected on the screen to form an image or "image". In the LCD system, the light from the light source is selectively polarized in a specific direction before being incident on the screen. On the LC layer. The LC layer may have a selectively applied voltage to determine the orientation of the material molecules in a certain way. Then, during the light traveling through the LC layer, Selectively change the polarization of the light to be incident on the LC layer. LCD systems usually include a polarizing beam splitter (pBS). The light reflected by the LCD with 98161.doc 200527114 will have a certain polarization state and will reflect or penetrate the PBS. (Depending on the system structure), and then incident on the projection optics. This light forms the party pixels of the image. Conversely, polarized light perpendicular to the bright pixels is prevented from reaching the optics and becomes dark. Here In the method, an image can be formed by a plurality of bright state pixels and dark state pixels, and a scrolling image can be formed by scrolling an input signal to a transistor matrix in the LCD. Contrast of a known LCD display system Less desirable. This is because the darkest degree is determined by the light leakage of the polarizer. This may also be caused by the residual birefringence in the liquid crystal layer caused by the non-ideal molecular orientation distribution, and by individual polarized light-dependent components. The optical axis is misaligned. In addition, when the image is a dark image, because the darkest setting is set, the image formed cannot be accepted because almost no details can be seen Finally, known LCD display systems can use polarizers or other retarders to improve the image effect by enhancing contrast or viewing angle dependence. However, these components will eventually cause material overheating over time [Description] According to an exemplary embodiment, an LCD display includes a light source and a light source disposed between the light source and a polarization beam splitter (pBS)] ^ (:: 1) brightness Adjusting device According to another exemplary embodiment of the present invention, a method for forming a high-contrast but darker image on a screen of an LCD display device includes: providing a light source between a light source and a polarization beam splitter (PBS); LCD brightness adjustment farm; and selectively changing the molecular orientation of liquid crystal molecules in the LCD brightness adjustment device. Selectively changing the orientation of the liquid crystal molecules will affect the polarization vector output of the LCD brightness adjustment output from the LCD panel to the rest of the light path. Therefore, the intensity of the light of the matrix display panel of the positive lighting system is reduced. As a result, the amount of light that can pass through the total light path is reduced, which reduces the amount of light reaching the eyes of the viewer. The invention will be better understood from the detailed description which follows with reference to the accompanying drawings. It should be noted that the features of the drawings are not necessarily drawn to scale. In fact, the size may be arbitrarily enlarged or reduced to make the explanation clearer. [Embodiment] For the purpose of explanation rather than limitation, exemplary embodiments for revealing specific details are proposed in the following detailed description in order to fully understand the exemplary embodiments. However, those familiar with the technology and benefiting from this specification should be aware of other specific embodiments that do not use the specific details disclosed herein. In addition, descriptions of well-known devices, circuits, and methods may be omitted to prevent obscuring the description of the present invention. Finally, similar reference numbers represent similar parts. In brief, the exemplary embodiments relate to a method and apparatus for selectively providing dark (sometimes referred to as "low light") and high-contrast images on a display screen of an LCD display device. As an illustration, an LCD brightness adjustment device selectively changes the magnitude of the vertical polarization vector it emits, so that the shirt image intensity is selectively changed to a desired intensity. As this specification continues, it will become clearer, because during the display of dark images, the LED brightness adjustment device will reduce the luminosity of light on the LCD panel, so the contrast j is maintained at a relatively high contrast. In this way, # when the maximum achievable system brightness is not needed, will reduce the intensity of the darkest pixels in the displayed image. FIG. 1 illustrates an LCD projection display device 9816l.doc 200527114 (LCD display) 100 according to an exemplary embodiment. Please note that the LCD projection display device 100 can be incorporated into a front display device. The LCD display 100 includes a lighting system (or lighting unit) 101. The lighting system may be a discharge gas type light source (for example, a high-pressure mercury lamp, an inert gas arc lamp or a metallized metal lamp), an LED array, or a display device for emitting Other known light sources containing red, green and blue (R, G, B) light. In addition, the lighting system 101 may include a parabolic mirror or the like. The LCD display 100 may include various well-known elements for LCD imaging. The light from the lighting system 101 passes through a group of beams used to shape the beam > optical elements 102-103, causing the display to be illuminated with a rectangular and homogeneous beam. Then, the light from the beam shaping optical element 103 is incident on a polarization conversion system (PCS) 104. This processing sequence converts the unpolarized light emitted by the lighting system 101 into a polarized light beam without large light loss. As an illustration, the PCS1 {) 4 includes a reflective polarization beam splitting optical element (for example, a -group polarization beam splitter) for splitting a light beam by reflecting a polarization mode of the light beam in a direction other than the other polarization modes. Of polarization mode. At some points in the PCS 104, the geometric separation of the two, positive-parent polarization modes, has prompted the use of polarization rotation elements to convert one of these two modes to the opposite. Judging from month to month, the elements 101_104 are all a ,,, a ...... u ~ π instrument w 芩 dead body / r is known and specified. A detailed description of 711 pieces and their functions, so as not to confuse the present invention. The detailed description of their components can be found in ——Guang et al. 93. The content of this case is explicitly incorporated by reference into 98l6l.doc 200527114. The light emitted from the PCS 104 is incident on a relay lens 108 and is reflected by a reflective surface 10 9 (shown as a mirror in the figure). . The light is incident on a second relay lens 110 and then travels through an LCD brightness adjuster 111 (illustrated as a transmissive LCD panel). After traveling through the LCD brightness adjuster 111, light is incident on a polarization beam splitter (PBS) 112. As this manual continues to become more clear, the LCD brightness adjuster 1 丨 丨 and PBS112 are used to control the intensity of the light incident on the display panels 115-117, and therefore set to reach the projection lens 113. Maximum intensity of light and displayed image. Appropriately polarized light travels directly through the PBS 112 and is incident on a prism system 114 composed of prism elements to guide red light to a red liquid aa panel 1 1 5 and a green liquid crystal panel 1 1 6 And a blue liquid crystal panel 117. After being adjusted by the corresponding panels 115-117, the light is transmitted to the PBS 112 to separate the light according to the polarization state, and the bright state light (bright state pixels) of each color is reflected by the PBS 112 and faces the Projection lens Π3. The polarization of the dark light (dark pixels) is orthogonal to the polarization of the reflected light toward the projection lens 113. The dark light (dark pixels) is transmitted away from the projection lens 113. In this method, dark light and bright light form an image on a display screen (not shown). As mentioned above, the LCD brightness adjuster 111 helps to reduce the overall luminosity of "dark" images (eg, night recordings or photos) on the display. In known systems, there are significant problems when displaying dark photos or video scenes. For example, in known systems, this reduction in luminosity is equivalent to reducing only the luminosity of bright light. For this purpose, in known systems, the darkest pixels maintain their 98161.doc 200527114 intensity regardless of the image content. In other words, the darkest pixels in both dark and light images are the same. Thus, in a dark image, the contrast between the brightest and darkest pixels is poor, and in some cases, the image appears difficult to recognize. Exemplary embodiments address these and other disadvantages of known devices. The LCD brightness adjuster 111 is an LCD device (unit) for selectively changing the polarization state of light passing through the brightness adjuster. In an exemplary embodiment, the brightness adjuster is 90 °. The nematic unit is reversed, but other LCD devices can be used depending on the display architecture. Please note that, in an exemplary embodiment, the LCD brightness adjuster lu may be integrated with the pcs 104. Although 90. Twisted nematic units are extremely beneficial and easy for manufacturers, and are most often used in LCDs, but other devices can be used as brightness correctors. For example, the display system may consist of a single panel using successive red, green and blue flash times. In an exemplary embodiment, since the ferroelectric display effect is relatively fast and the red, green, and blue flash comparison can be individually optimized, the implementation of the ferroelectric unit can be helpful. In another exemplary embodiment, the brightness adjuster may be a device with a length of 1 Electrically Controlled Birefringence (ECB). The advantages of the ECB effect are: the spectral output of the ECB unit can be controlled by the voltage on the LCD layer; and the brightness adjustment effect can be adjusted according to the maximum necessary light intensity of the red, green and blue used to present the image. In any case, the polarization changed by the brightness adjuster Π1 is used to selectively prevent light of a specific polarization state from being transmitted to the prism system Π4. This creates a dark image on the display. Alternatively, the LCD brightness adjustment 98161.doc 200527114 may not change the light incident thereon, and the entire light is transmitted to the prism system 114. This creates a high-intensity or normal image on the display. Finally, the light rays can be polarized in an elliptical shape, causing the light rays to have a vector component transmitted by the PBS U2, and the PBS 112 reflects their components in a direction opposite to the projection lens 113. In this case, the resulting image is a medium-brightness image on the screen. Please note that in these and other embodiments, a polarizer (for example, the polarizer 518 shown in FIG. 5) may be disposed between the LCD brightness adjuster 111 and the PBS 112. This polarizer can be used if the quality of the polarization state of the light incident on the LCD brightness adjuster is insufficient (for example, the spectral distribution of the light output of the brightness adjuster in a dark-state brightness adjuster may be due to optical components in the lighting system Coloring problems in birefringence). This additional polarizer will effectively absorb impure light in the beam. As an illustration, the polarizer is a reflective polarizer, such as: interference coating polarizer; Brewster sheet; birefringent layer; holographic element; or grid grid polarizer. In an embodiment, the LCD brightness adjustment device may include a birefringence compensation layer to substantially optimize the contrast of the LCD brightness adjuster 111 in the main direction of the light beam traveling through the LCD brightness adjuster 111. FIG. 2 is a diagram showing that the LcD brightness adjuster in the LCD display system 100 shown in FIG. 1 is in a 咼 intensity output mode. In this exemplary embodiment, the orientation of the liquid crystal molecules of the B00 shell adjuster Hi causes the input polarization vector of the light consisting of * RGB light 105-107 (labeled 201 in the figure) 2022161. doc -11-200527114 Go through the LCD brightness adjuster 111 under the influence of “,” and in this way, the output polarization vector 203 is relative to the input polarization vector: it does not change. In this exemplary embodiment, the brightness adjuster 111 does not substantially affect the polarization state of the light traveling through the brightness adjuster. That is, in direction 205, the PBS 112 reflects only about 1% of the light. Then, the emitted light with a polarization state of 203 (conceptually shown as 204 in the figure) is incident on the pBS 112 and is actually completely transmitted through the pBs ι2. At this stage, there is virtually no light in the direction of 205. reflection. As described above, the light 204 travels through the prism system 114 and is tuned into dark-state pixels (reflected at direction 205 at this stage) and dark-state pixels (reflected to the projection lens 113) for image formation. Obviously, in the state where the on-state voltage is applied to the LCD as an example, the output to the projection lens forms a bright or normal brightness image on the display screen. FIG. 3 illustrates that the LCD projection display shown in FIG. 1 is in a low-intensity output state, thereby forming a dark image on the display screen. In the exemplary embodiment shown in FIG. 3, the orientation of the liquid crystal material molecules of the LCD brightness adjuster causes the light having an incident polarization in a certain direction to change from the LCD brightness adjuster having a polarization vector orthogonal to the input polarization to ϊ issue. For example, in this exemplary embodiment, the incident rays 105-107 (conceptually shown as 301 in the figure) have an input polarization state (Pin) that is not drawn as a vector 302. After traveling through the LCD brightness adjuster 111, the polarization state of substantially all light rays is rotated by 90 °, and is emitted from the LCD brightness adjuster having an output polarization state (pQut) shown as a vector 303. 98161.doc -12- 200527114 together with a substantial part of the light emitted from the LCD brightness adjuster 1 π with a polarization state orthogonal to the transmission axis of the PBS 112, virtually all light 301 goes in the direction 304 (as opposed to the Direction of the projection lens 113). In addition, only a small portion (approximately 1% series) of the light 301 will be emitted from the LCD brightness adjuster 111 having a polarization state aligned with the transmission axis of the PBS 112. This light (conceptually shown as 305 in the figure) is incident on the prism system, thereby being modulated by the LC panels 115-117. As described above, according to the functions of the LC panels 115-117, the light returned to the PBS 112 is reflected toward the projection lens 113 or direction 30. If the reflection is directed toward the projection lens 113, it is the brightest. State; if the reflection is in the direction 304, it is the darkest state. However, without the effect of the LCD brightness adjuster, the light 305 modulated by the LC panels 115-117 represents a small portion of the light that will be transmitted to the projection lens 113 or to the direction 304. In an exemplary embodiment, a light trap is included to absorb light reflected by the PBS between the LCD brightness adjuster and the LC panels. In these exemplary embodiments, the LCD brightness adjuster 111 reduces the overall intensity of the light of the LC panels, and the darkest pixels become darker, and in the manner described so far, the contrast is The device is known to be improved. As mentioned above, in the known LCD type display device, the control of the black state light is limited by the ability of the polarizer and the liquid crystal electro-optical effect. Polarizers, LC materials, and alignment are not ideal 'and are intended to prevent some of the light reaching the display screen from passing through and leaking. For its part, in known systems, the intensity of the darkest pixel irrespective of brightness ' is basically weird. This is explained when the image displayed by 98161.doc -13- 200527114 does not have any pixels at the maximum brightness, the contrast of the image is reduced. For example, if the LCD panel can provide a contrast and the image being displayed has 50% light output The brightest pixels (or 50% of the maximum, called the 50% maximum) will drive the LCD accordingly. However, when the brightest pixels are at 50% maximum, the darkest pixels are still at 1% maximum, and the contrast of the displayed image is reduced to only 50: 1. Assuming that the brightest pixels are at a maximum of 5% and the darkest pixels are maintained at a maximum of 1%, the contrast achieved in the displayed image is further reduced to only 5: 1. Obviously, in non-low-light images, it is known that the contrast in LCD systems is too low to accept, and it will lose all the details of the image application. However, according to the exemplary embodiments described herein, the intensity of the brightest pixels is controlled by the LCD brightness adjuster and not controlled by the panels (e.g., 115-117). This means that the intensity of the light is reduced before it reaches these £ c panels. If the brightest pixel in the image is 50%; the shell adjuster adjusts the luminosity of the light to the LCD to 50%; this will also reduce the intensity of the darkest pixel in the displayed image by 50% . This caused the brightest pixels to be at a maximum of 50%, and now the darkest pixels were reduced to only a maximum of 0.5%, resulting in the contrast of the displayed image being ι〇〇 ·· ι. The comparison of the scene achieved in this particular example is twice that of known methods and equipment. The brightest pixel is 50 /. In the second case of the maximum value, the brightness adjuster adjusts the luminosity of the light to the LCD to the maximum value of 5%; and the brightness adjuster also adjusts the darkest pixel to the maximum value of 95%. This results in the brightest pixel at 5 /. The maximum value is observed, and now the darkest pixels are reduced to only 0. The maximum value of 98161.doc -14- 200527114 value 'causes the contrast of the displayed image to be 100: 1 again. In this particular example, the contrast improvement of the image achieved is 20 times compared to known equipment and methods. Another useful aspect of this anomalous embodiment is the dependence of the contrast ratio on the viewing angle. As we all know, when the non-LCD plane normal is 0. Contrast can be affected when viewing the LCD image at a degree. However, because the LCD brightness adjuster ' of the illustrative embodiment described herein is not viewed directly, the contrast is not adversely affected in this manner. FIG. 4 illustrates a diagram of the LCD brightness adjuster in the system 100 shown in FIG. 1 in a medium-intensity output mode according to an exemplary embodiment. It is well known that the electro-optical effect of a liquid crystal material depends on the voltage applied to the liquid crystal. For example, the voltage of light transmission relative to a 90-degree twisted nematic LCD panel decreases sharply with the applied voltage. For its part, by applying a voltage corresponding to a desired level to the yoke, the transmittance can be reduced to a selected level, and thus the brightness can be reduced to a selected level.忒 LCD case adjuster U1 can also be used to make the brightness at a high brightness (for example, the exemplary embodiment shown in FIG. 2) and a low brightness (for example, the irregular embodiment shown in FIG. 3) Continuous change between. In the exemplary embodiment shown in FIG. 4, the orientation of the liquid crystal material molecules of the LCD brightness adjuster causes the light with incident linear polarization to be withdrawn from the redundancy of the LCD with elliptical polarization; Light rays that are parallel and perpendicular to the polarization vector component of the input polarization. For example, in this exemplary embodiment, the incident rays 105-107 (conceptually shown as 401 in the figure) have an input polarization state (Prin) shown as a vector 402. After traveling through the LCD brightness 98161.doc -15- 200527114 adjuster 111, the light has a polarization state (Pout) 403 in an elliptical state as shown in the figure. Please note that in this exemplary embodiment, 1 > is essentially polarized in a circle, which means p parallel to the input polarization vector 402. The magnitude of the polarization vector component is equal to the value of the polarization vector division perpendicular to the input polarization vector 402. However, it is obvious that by selecting other voltages to be applied to the LCD brightness adjuster, other elliptical states can be selected. In the exemplary embodiment described with reference to FIG. 4, together with about one-half of the light energy emitted from the LCD brightness adjuster j J j having a polarization state of the transmission axis of the positive PBS 112 112, actually Approximately 50% of the light 401 is reflected in the direction 4 0 4 (opposite to the direction of the e-hai projection lens 113). In addition, only about $ 0% of light 401 will be emitted from the LCD brightness adjuster with a polarization state aligned with the transmission axis of the PBS 112. This light (conceptually shown as 405 in the figure) is incident on the prism system 114, thereby being modulated by the LC panels 115-117. As described above, according to the role of individual pixels in the LC panels 11 5-117, the light returned from their pixels to the PBS 112 is reflected toward the projection lens 113 or direction 404. If the reflection is directed toward the projection The lens 3 is a bright pixel; if the reflection is in the direction 404, it is a dark pixel. FIG. 5 illustrates a CD projection display 50 according to an exemplary embodiment. The LCD display 500 has the features of the exemplary embodiment described above with reference to the exemplary embodiment of Figs. Accordingly, these common features will not be described repeatedly in the related detailed description. The side display 500 is a scroll-type color display device including an illumination source 501. The remote illumination source 501 includes a parabolic reflector and a light-emitting element, as described above in 98161.doc -16-200527114. The light from the lighting unit 501 passes through a set of beam-shaping optical elements 502_503 for shaping the beam, causing the display to be illuminated with a rectangular and homogeneous beam. Next, the light from the beam-shaping optical element 503 is incident on a polarization conversion system (1 > (: ^) 504. This processing sequence converts the unpolarized light emitted by the illumination system 101 into a polarized light beam without There will be significant loss of light energy. The display also includes a wavelength-selective mirror 50.5, which may be a dielectric stacked reflector or a dichroic mirror well known in physical optics. Their wavelength-selective mirrors will reflect a certain wavelength. Light (e.g., red light 506), and transmits all other wavelengths (e.g., blue and green light 507). Continuing along those lines, green light 508 is reflected and blue light 509 is transmitted as shown. Rotating prism 5 The 10 series is used to scan images in a manner well known in the art. And the mirror 5 11 and the lens 5 12 help to focus and focus the light as needed. Finally, the wavelength selection mirror 5 13 functions the same way as the wavelength Choose the mode and type of action of mirror 505; however, mirror 513 is used to recombine the light into pbs 5 14. PBS 5 14 acts in a known manner to direct light to lc panel 515 (shown as LCOS panel) And will be tuned The light is guided to the projection optical element 5 16. Since the functions of their various elements are already well known to us, further explanations will be omitted in the related detailed description. Finally, please note that in conjunction with the description of this exemplary embodiment For features and other features and descriptions, see US Patent No. 6,563,551 to Janssen et al. The contents of this patent are expressly incorporated herein by reference. An LCD brightness adjuster 5 1 7 is inserted into the illumination source 5 01 and the pbs 5 to 14. The LCD brightness adjuster 517 helps to control the display (98161.doc 17 200527114 in the picture)
亮度，同時維持足夠的對比，甚 忒LCD焭度調整器5丨7的功能實 示範（生具體實施例所描述之LCD 未繪示）上所形成之影像的 至維持低光度影像的對比 質上完全相同於前文配合 壳度調整器的功能。 已詳細描述各項示範性且妒眘 ^ /、體實她例，熟悉此項技術且得 显於此份說明書的人士應清楚知道本發明的修改方案。這 些修改方案及變化版都屬於隨附t請專利範圍的範㈣。 【圖式簡單說明】 之LCD投影顯示裝置的 圖1繪示根據示範性具體實施例 概要圖。 圖2繪示圖i所示之LCD顯示裝置的透視圖，用以呈現在 高強度輸出模式中LCD亮度調整裝置所發出之光線的偏光 狀悲。 圖3繪示圖1所示之LCD顯示裝置的透視圖，用以呈現在 低強度輸出模式中LCD亮度調整裝置所發出之光線的偏光 狀態。 圖4繪示圖1所示之LCD顯示裝置的透視圖，用以呈現在 中寺強度輸出核式中LCD免度調整裝置所發出之光線的偏 光狀態。 圖5繪示根據示範性具體實施例之LCD投影顯示裝置的 概要圖。 【主要元件符號說明】 100 LCD投影顯示裝置（LCD顯示器） 101 照明系統（或照明單元） 98161.doc -18 - 200527114 102-103 光束成形光學元件 104 偏光轉換系統（PCS) 105-107 RGB光 108 中繼透鏡 109 反射表面 110 第二中繼透鏡 111 LCD亮度調整器 112 偏振分光器（PBS) 113 投影透鏡 114 棱鏡系統 115 紅色液晶面板 116 綠色液晶面板 117 藍色液晶面板 201 光線 202 輸入偏振向量 203 輸出偏振向量 204 光線 205 方向 301 光線 302 輸入偏振向量 303 輸出偏振向量 304 方向 305 光線 401 光線 98161.doc -19-Brightness, while maintaining sufficient contrast, even the demonstration of the function of the LCD brightness adjuster 5 丨 7 (the LCD is not shown in the specific embodiment) to maintain the contrast quality of low-lightness images Exactly the same function as the shell adjuster. Exemplary and jealous examples have been described in detail, and those who are familiar with this technology and who will be apparent from this specification should be aware of the modification of the present invention. These amendments and variations are within the scope of the attached patents. [Brief Description of the Drawings] FIG. 1 shows a schematic diagram of an LCD projection display device according to an exemplary embodiment. Fig. 2 is a perspective view of the LCD display device shown in Fig. I, for showing the polarized light of the light emitted by the LCD brightness adjustment device in the high-intensity output mode. FIG. 3 is a perspective view of the LCD display device shown in FIG. 1 to show the polarization state of the light emitted by the LCD brightness adjustment device in the low-intensity output mode. FIG. 4 is a perspective view of the LCD display device shown in FIG. 1 for presenting the polarization state of light emitted by the LCD immunity adjustment device in the Nakaji intensity output core type. FIG. 5 illustrates a schematic diagram of an LCD projection display device according to an exemplary embodiment. [Symbol description of main components] 100 LCD projection display device (LCD display) 101 Lighting system (or lighting unit) 98161.doc -18-200527114 102-103 Beam shaping optical element 104 Polarization conversion system (PCS) 105-107 RGB light 108 Relay lens 109 Reflective surface 110 Second relay lens 111 LCD brightness adjuster 112 Polarizing beam splitter (PBS) 113 Projection lens 114 Prism system 115 Red LCD panel 116 Green LCD panel 117 Blue LCD panel 201 Light rays 202 Input polarization vector 203 Output polarization vector 204 light 205 direction 301 light 302 input polarization vector 303 output polarization vector 304 direction 305 light 401 light 98161.doc -19-
200527114 402 輸入偏振向量 403 輸出偏振向量 404 方向 405 光線 Pin 輸入偏振狀態 P out 輸出偏振狀態 500 LCD投影顯示器 501 照明源 502-503 光束成形光學元件 504 偏光轉換系統（PCS) 505, 513 波長選擇鏡 506 紅光 507 藍光和綠光 508 綠光 509 藍光 510 旋轉式棱鏡 511 鏡 512 透鏡 514 偏振分光器（PBS) 515 LC面板 516 投影光學元件 98161.doc - 20 -200527114 402 Input polarization vector 403 Output polarization vector 404 Direction 405 Light Pin Input polarization state P out Output polarization state 500 LCD projection display 501 Illumination source 502-503 Beam shaping optics 504 Polarization conversion system (PCS) 505, 513 Wavelength selection mirror 506 Red light 507 Blue light and green light 508 Green light 509 Blue light 510 Rotating prism 511 Mirror 512 Lens 514 Polarizing beam splitter (PBS) 515 LC panel 516 Projection optics 98161.doc-20-