1255355 九、發明說明： 【發明所屬之技術領域】 本發明係關於一種用作光偏振轉換（1 ight polarization conversion)之光學元件（optical element)，尤指一種應用於 LCD/LCoS投影機領域的偏振轉換系統。 【先前技術】 如該行業者所知，液晶類型投影顯示系統例如液晶（Liquid1255355 IX. Description of the Invention: [Technical Field] The present invention relates to an optical element used as a light polarization conversion, and more particularly to a polarization applied in the field of LCD/LCoS projectors. Conversion system. [Prior Art] Liquid crystal type projection display system such as liquid crystal (Liquid) as known to the industry
Crystal Display，LCD)投影機以及液晶矽晶（Uquid ClTstal 〇n Silicon，LCoS)投影機一般需要先將照明光源以光偏振轉換系統 轉換成相同的偏振態，例如P偏光或s偏光。其中，l⑶投影機因 運作時光線係穿透過LCD面板，所以屬於穿透式投影機 ，而 LCoS、 财投影機則是靠光線反射的顧顯像，所以又概稱為反射式投影 機。 第1圖顯示-種習知技藝的光偏振轉換系統。如圖所示，習知 1255355 光偏振轉換系統10包括一固態導光管12以及設於固態導光管12 入口面14的菱鏡組16，其包括兩個90-45-45度角的三角菱鏡162 以及164、將一個四角菱鏡(rh〇mb)i66夾設其中而成。三角菱鏡 162以及164的45度角鏡面上鐘有偏振光束分光(Polarization Beam Splitting，PBS)鍍膜168。在四角菱鏡166與固態導光管 12入口面14之間，另設有二分之一波板（Half-Wave Plate， HWP)18 。 從某光源產生的未極化(unpolarized)光線22由三角菱鏡162 進入’其中相對於PBS鍍膜168所定義的P偏光24穿透過PBS鑛 膜⑽，直接射入固態導光管12，而s偏光26則被pBS鍛膜⑽ 反射至三角菱鏡164的45度角PBS鍍膜168，隨後再被反射至二 分之一波板18。當S偏光26穿過二分之一波板18後，其電場偏 振方向被轉換9〇度角，成為p偏光28，.並進入到固態導光管a 中。藉由此方式，光線被線性極化成相同的偏振態，然後在固態 導光官12中經過多次的反射後，形成在導光管出口的均勻化光線。 1255355 【發明内容】 本發明提供一種改良之偏振轉換系統。 根據本發明之較佳實施例，本發明提供一種偏振轉換系統，包 含有一中空導光管，其由四片側反射鏡片定義出剖面成矩形之光 通道，並於該光通道之入口端設有一前反射鏡片，該前反射鏡片 具有一開口，讓由光源匯聚之未極化光束經由該開口入射至該光 通道内；一第一偏振光束分光模組，緊鄰該光通道之出口端，且 該第-偏振光束分光模組具有—第―偏振分光面，以45度角傾斜 配置，其中該第-偏振分光面容許該未極化光束之第—偏振態光 束通過，而反職未極化光束之第二偏振態光束，其巾該第一偏 ;一延遲板，設於該第Crystal Display (LCD) projectors and liquid crystal twin crystal (LCoS) projectors typically require the illumination source to be converted to the same polarization state, such as P-polarized or s-polarized light, by a light polarization conversion system. Among them, the l(3) projector is a transmissive projector because the light system penetrates the LCD panel during operation, while the LCoS and the financial projector are reflected by the light, so it is also called a reflective projector. Figure 1 shows a light polarization conversion system of the prior art. As shown, the conventional 1255355 light polarization conversion system 10 includes a solid state light pipe 12 and a prism group 16 disposed on the inlet face 14 of the solid state light pipe 12, which includes two triangles of 90-45-45 degree angles. The mirrors 162 and 164 are formed by sandwiching a four-angled mirror (rh〇mb) i66. The triangular mirrors of the triangular mirrors 162 and 164 have a Polarization Beam Splitting (PBS) coating 168. Between the four-corner mirror 166 and the inlet face 14 of the solid-state light pipe 12, a half-wave plate (HWP) 18 is additionally provided. The unpolarized light 22 generated from a light source enters by the triangular prism 162, wherein the P polarized light 24 defined relative to the PBS coating 168 penetrates the PBS mineral film (10) and directly enters the solid state light guide tube 12, and The polarized light 26 is reflected by the pBS forged film (10) to the 45 degree angle PBS coating 168 of the triangular prism 164, and then reflected to the half wave plate 18. When the S-polarized light 26 passes through the half-wave plate 18, its electric field polarization direction is converted to a 9-degree angle to become p-polarized light 28, and enters the solid-state light guide tube a. In this way, the light is linearly polarized into the same polarization state, and then after multiple reflections in the solid state light guide 12, uniform light is formed at the exit of the light pipe. 1255355 SUMMARY OF THE INVENTION The present invention provides an improved polarization conversion system. According to a preferred embodiment of the present invention, the present invention provides a polarization conversion system including a hollow light guide tube defined by four side reflection lenses as a light passage having a rectangular cross section, and a front end at the entrance end of the optical passage. a reflective lens, the front reflective lens having an opening through which the unpolarized light beam concentrated by the light source is incident; a first polarized beam splitting module adjacent to the exit end of the optical channel, and the first The polarized beam splitting module has a -first polarization splitting plane disposed obliquely at an angle of 45 degrees, wherein the first-polarized splitting plane allows the first-polarized beam of the unpolarized beam to pass, and the counter-polarized beam is passed a second polarization state beam, the first bias of the towel; a retardation plate, disposed in the first
再次旋轉一個相位(9/2， 而射出該延遲板時，其電場偏振方向總 振悲與該第二偏振態係為相位差為9〇度； 偏振光束分光模組上方；一及射错，抑 1255355 共被旋轉她^及—第二偏振光束分光模組，設於該第一偏 振光束分光餘下方，且該第二難縣分光模組具有—第二偏 振分光面，以相對於該第一偏振分光面9〇度角傾斜配置，其中該 第二偏振分光面反射通過該延遲板之該第二偏振態光束。 為壤本發明之上述目的、特徵、和優點能更明顯易懂，下文特 舉較佳實施方式’她合所_式，作詳細綱如下。然而如下 之較佳實施方式與圖式健參考與說彻，並制來對本發明加 以限制者。 【實施方式】 請參閱第2圖，其顯示依據本發明較佳實施例之偏振轉換系統 100。本發明偏振轉換系統1〇〇包括一中空導光管12〇，其長度為 L，由側反射鏡片組成剖面為矩形之光通道（Iight 士如此i)，以及 設置於入口端（entrance face)140的前反射鏡片122所構成。前 反射鏡片122上提供有一開口 124,讓由光源(圖未示）匯聚之光束 10 1255355 222經由開ο 124入射至該光通道内。 在導光管120的出口端160，設有一偏振光束分光模組丨，包 _ 含有一呈45度角傾斜配置之偏振光束分光(PBS)面丨92，可讓相對 · 於PBS面192所定義的p偏光224穿透過PBS面192,而讓相對於 PBS面192所定義的s偏光226反射。 偏振光束分光模組1可以為一反射式極化片（ref lecHve polarizer) ’或者單一格線方向佈設有細密銀或紹線(Wiregrw) 之光柵元件（polarization splitter module)，例如 Moxtek 公司 所k供之偏振分光器’或者是偏振光束分光器（p〇larizati〇n ]3eam splitter)，或者由45角鏡面上鍍有PBS鍍膜的菱鏡立方體。偏 振分光模組1需具有咼消光比以及低反射耗損（reflect on losses) 〇 在偏振光束分光模組1之上方設有一延遲板(retar(Jation piate)182,並在延遲板182上設置一反射鏡184。經由PBS面192 11 1255355 反射的S偏光226進入延遲叔 42’其電場偏振方向被旋轉一個相 位（0/2)，再由反射鏡184 久射弟二次進入延遲板182，其電場偏 振方向再次旋轉-個相位（θ/2)，如此使其相位轉移特定角度 Θ例如’ Θ約90度角，使其轉換成為ρ偏光，即可順利通 過偏振光束分光模組1之PBS面192。 第2圖中，在偏振光束分光模組1之下方設有-偏振光束分光 模組2，其具有一與PBS面192呈45度角傾斜配置之pBs面脱， 可讓相對於PBS面192所定義的8偏光穿透過pBS面194，而讓相 對於PBS面192所定義的p偏光228反射。穿透過哪面192的p 偏光224以及經由偏振光束分光模組2反射的p偏光228，再經由 透鏡組300投射至LCD或LCoS為投影面板。 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，皆應屬本發明專利之涵蓋範圍。 【圖式簡單說明】 12 1255355 第i圖顯示一種習知技藝的光偏振轉換系統。 第2圖顯示依據本發明較佳實施例之偏振轉換系統。 【主要元件符號說明】 10 光偏振轉換系統 14 入口面 18 二分之一波板 24 P偏光 28 P偏光 162三角菱鏡 166四角菱鏡 1 偏振光束分光模組 100偏振轉換系統 122前反射鏡片 140入口端 182延遲板 192 PBS 面 222光束 12 固態導光管 16 菱鏡組 22 未極化光線 26 S偏光 164 三角菱鏡 168 PBS鍍膜 2 偏振光束分光模組 120 導光管 124 開口 160 出口端 184 反射鏡 194 PBS 面 224 P偏光 13 1255355 226 S偏光 228 P偏光 300透鏡組Rotating one phase again (9/2, when the retardation plate is emitted, the total polarization of the electric field polarization direction and the second polarization state are phase difference of 9 ; degrees; above the polarized beam splitting module; 1255355 is rotated by a ^ and - a second polarized beam splitting module, disposed under the first polarized beam splitting light, and the second difficult county splitting module has a second polarizing beam splitting surface, relative to the first a polarizing beam splitting surface 9 is disposed at an oblique angle, wherein the second polarizing beam splitting surface reflects the second polarized light beam passing through the retardation plate. The above objects, features, and advantages of the present invention are more apparent and easy to understand. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S) The preferred embodiment of the present invention is described in detail below. However, the following preferred embodiments and drawings are intended to be illustrative and to limit the invention. 2 is a diagram showing a polarization conversion system 100 in accordance with a preferred embodiment of the present invention. The polarization conversion system 1 of the present invention includes a hollow light guide 12 〇 having a length L and consisting of a side reflector having a rectangular cross section. aisle The Iight is constructed such that i) and the front reflecting mirror 122 disposed at the entrance face 140. The front reflecting mirror 122 is provided with an opening 124 for allowing the light beam 10 1255355 222 concentrated by the light source (not shown) to be opened. ο 124 is incident into the optical channel. At the exit end 160 of the light pipe 120, a polarizing beam splitting module 设有 is provided, and the package _ includes a polarized beam splitting (PBS) face 92 disposed at an angle of 45 degrees. The p-polarized light 224 defined by the PBS surface 192 is passed through the PBS surface 192 to reflect the s-polarized light 226 defined by the PBS surface 192. The polarized beam splitting module 1 can be a reflective polarizer (ref lecHve polarizer) 'Or a single grating direction with a fine silver or Wiregrw grating splitter module, such as a polarizing beam splitter from Moxtek's or a polarizing beam splitter (p〇larizati〇) n ]3eam splitter), or a mirrored mirror surface coated with PBS on a 45-corner mirror. The polarization splitting module 1 needs to have a 咼 extinction ratio and a low reflectance loss on the polarized beam splitting mode. A retardation plate (rear (Jation piate) 182 is disposed above 1 and a mirror 184 is disposed on the retardation plate 182. The S polarized light 226 reflected by the PBS surface 192 11 1255355 enters the delay uncle 42' whose electric field polarization direction is rotated by one. The phase (0/2) is further incident on the retardation plate 182 by the mirror 184 for a long time, and the direction of polarization of the electric field is rotated again by one phase (θ/2), so that its phase is shifted by a specific angle, for example, 'Θ90 The angle of the angle is converted into ρ-polarized light, and the PBS surface 192 of the polarization beam splitting module 1 can be smoothly passed. In the second figure, a polarization beam splitting module 2 is disposed below the polarizing beam splitting module 1 and has a pBs surface which is disposed at an angle of 45 degrees to the PBS surface 192, so as to be opposite to the PBS surface 192. The defined 8 polarized light penetrates the pBS face 194 and is reflected by the p-polarized light 228 defined relative to the PBS face 192. The p-polarized light 224 penetrating through the surface 192 and the p-polarized light 228 reflected by the polarizing beam splitting module 2 are projected onto the LCD or LCoS via the lens group 300 as a projection panel. The above is only the preferred embodiment of the present invention, and all changes and modifications made by the scope of the present invention should be covered by the present invention. [Simple Description of the Drawings] 12 1255355 The figure i shows a light polarization conversion system of the prior art. Figure 2 shows a polarization conversion system in accordance with a preferred embodiment of the present invention. [Main component symbol description] 10 Light polarization conversion system 14 Entrance surface 18 Half wave plate 24 P Polarized light 28 P Polarized light 162 Triangle prism 166 Four-pointed mirror 1 Polarized beam splitting module 100 Polarization conversion system 122 Front reflection lens 140 Inlet end 182 retardation plate 192 PBS surface 222 beam 12 solid state light pipe 16 lens group 22 unpolarized light 26 S polarized light 164 triangular prism 168 PBS coating 2 polarized beam splitting module 120 light pipe 124 opening 160 outlet end 184 Mirror 194 PBS face 224 P polarized light 13 1255355 226 S polarized light 228 P polarized 300 lens group
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