TW588193B - Reflection type liquid crystal display element, display device, projection optical system and projection display system - Google Patents
Reflection type liquid crystal display element, display device, projection optical system and projection display system Download PDFInfo
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588193 ⑴ 狄、發明說明 (發明說明應敘明：發明所屬之技術領域、先前技術、内容、實施方式及圖式簡單說明) 技術領域 本發明係有關適於投影顯示系統等之反射型液晶（光電） 顯示元件、與該顯示元件組合使用之顯示裝置、投影光學 系統、及投影顯示系統。 背景技術 近年來，隨投影顯示之高精細化、小型化、及高亮度化 的發展，其顯示裝置亦可小型化、高精細化，且可達到高 度光利用效率之反射型裝置深受矚目且已趨於實用化。 其中報告有：與形成有透明電極之玻璃基板相對，如在 包含互補金屬氧半導體（CMOS ; Complementary Metal Oxide Semiconductor;互補型MOS)半導體電路之矽基板 上設置驅動元件，在其上配置形成鋁光反射電極之驅動電 路基板，在此等一對基板間注入垂直配向液晶材料之主動 型之反射型液晶顯示裝置（元件）（論文①：H. Kurogane等 人，Digests of SID1998，P33-36 (1998),及論文②：S. U c h i y a m a 等人，p r 〇 c e e d i n g s 〇 f I d w 2 0 0 0，P 1 1 8 3 -1 1 8 4 (2000))，藉由一部分的廠商實際形成商品化。 此處，所謂之垂直配向液晶材料，係指具有負介電常數 異方性（亦即，與液晶分子之長軸平行之介電常數ε ( || )與 垂直之介電常數ε (丄）之差：Δε (=ε (||) _ ε (丄為負） 的液晶材料。上述之透明電極-光反射電極間之施加電壓 為零時’液晶分子在基板面上大致垂直地配向，顯示正常 黑模式（Normally black mode)者。 588193 (2) 上述所報告之先前反射型裝置之垂直配向液晶層的厚 度（單元間隙）為3〜4 μιη，對驅動電壓（施加於液晶之電壓） 之液晶透過率的曲線（以下稱V-T曲線，但因係反射型裝 置，實測相當於裝置的反射率（但是，此時如後述，藉由 裝置，入射光如s偏光被偏光調制，而獲得ρ偏光之反射 光。）。）具有以約2 V之臨限值電壓上昇，以4〜6 V之施加 電壓達到最大值的特性。藉由在此等間改變電壓，使液晶 之透過率類比地改變，可表現灰階。圖1 4係顯示一種自上 述論文①中摘取的資料，其中報告：液晶層之厚度為3 μιη， 驅動電壓約± 4 V，反應速度（上昇時間+下降時間）約為1 7 msec0 液晶通常係在各巾貞或場使正負之電壓反轉驅動’上述之 裝置實際上表示係以最大± 4〜6 V的電壓驅動（由於正與負 之V-T曲線原則上對稱，因此V-T曲線通常僅以正值表 不）。±4〜6 V之液晶驅動電壓表不’驅動電晶體之有效而才 壓須在8〜12 V以上。 由於此遠大於一般之Μ 0 S處理的耐壓，因此形成於矽驅 動電路基板之像素内的液晶驅動電晶體上適用輕度摻雜 没極-源極（LDD; Lightly doped drain-source)構造等的高 耐壓處理。考慮製造成本及耗電等，其耐壓通常為8〜12 V。此即先前裝置以具有最大± 4〜6 V之V-T曲線之方式設 置裝置的理由。 此外，先前裝置上使用之垂直配向液晶材料的折射率異 方性Δη (亦即，與液晶分子之長軸方向平行之折射率n( || ) 588193 (3) 發明說明續頁 與其垂直之方向之折射率n(丄）之差：Δη(=η(|| ) - n(丄）） 為小於0. 1的值（典型而言約為0.08)，典型的像素間隙為 13·5 μπι (像素尺寸 13 μιη)。 近年來，如所周知的，特別凸顯出液晶顯示裝置缺點之 反應速度慢的問題，因而其快速化成為重要課題。一般而 言，液晶之反應速度（上昇時間及下降時間）如下列公式1 及公式2所示，係與液晶層之厚度d的二次方成正比，因 此，使液晶之層厚減少則有助於快速化。 上昇時間 τ on γ -d2 £(0)Ae(V2-Fc2) 公式1 下降時間τ off= .....公式2 (其中，Τ :液晶之黏度，d :液晶層之厚度，△ ε :液晶之 介電常數異方性，ε (0):真空之介電常數，K :液晶之彈 性常數’ V·施加於液晶的電壓（液晶驅動電壓）’ Vc·臨 限值電壓。） 但是，先前之垂直配向液晶顯示裝置，於減少液晶層之 厚度時，反應速度雖依據公式1及2而快速化，但是卻有為 使透過率飽和，所需之驅動電壓提高的問題。圖1 5顯示於 使用先前裝置使用之液晶材料（Δη = 0.082)系中，減少液晶 之層厚時的V-T曲線，圖16顯示飽和電壓因液晶層厚d的變 化。 如圖15、圖16所示，裝置之飽和電壓自液晶層厚度d為 2.5 μπι附近起急遽升高而超過6V，當d在2 μπι以下時還達 588193 (4) _____ 到1 Ο V。亦即，驅動電晶體之耐壓亦需要2 Ο V以上。而且， d在1.5 μιη厚以下時，透過率之絕對值未達到1 0 0 %，於1 μιη 厚時，不但僅獲得約3 0 %的透過率，且臨限值電壓亦升高。 此種現象係因垂直配向液晶隨d(單元間隙）變小，液晶分 子與配向膜之界面的相互作用（Interaction)，液晶分子因 施加電壓而對導向器的方向變化相對性變大。反之，液晶 層厚大時，因出現體積的性質，因而導向器容易移動，以 致上述界面上之相互作用的影響減少。 如上所述，液晶顯示裝置之驅動電壓提高時，一般的矽 驅動元件基板驅動困難。當然，雖可藉由提高像素驅動電 晶體的财壓來解決，但是一般而言此種處理複雜，不但成 本高、耗電大，且於提高财壓時，難免電晶體的尺寸增加。 因此，尤其很難以約1 0 μιη以下的小像素尺寸（或間隙）製 造此種高耐壓電晶體。 基於上述理由，使用先前之垂直配向液晶的反射型顯示 裝置，欲使液晶層的厚度在2.5μιη以下，目前實用上仍有 困難。 此外，如此減少液晶層厚，對施加電壓的反應性亦差， 且裝置製造良率降低。 再者，使用上述之先前裝置的投影光學系統如下所示， 欲保持高對比，必須使光學系統之F值（F N u m b e r)在3.5以 上，因而發生無法提高亮度的問題。 使用反射型液晶顯示裝置之投影系統，如圖1 7所示，需 要經由偏光分離裝置之紅（R)，綠（G)，藍（B)之各色用偏光 -10- 588193 (5) 分束器2 R，2 G，2 B，照射來自燈光源1之光束在使用垂直 配向液晶之反射型液晶顯示裝置3 R，3 G ’ 3 B上’並以合 成各色光之稜鏡（X-Cube稜鏡）4聚集被此等裝置偏光調制 的反射光，投射光1 〇 (P)經由投射透鏡5投射於屏幕（圖上 未顯示）的光學系統。 此時，照明反射型液晶顯示裝置3 R ’ 3 G ’ 3 B之照明光 學系統，係自來自白色燈光源1之白色光（P偏光成分與S偏 光成分混合之光1〇 (P，s))，通過複眼微透鏡6、偏光轉換 裝置7、及聚焦透鏡8等，形成s偏光i〇(s)，再度導至二向 色分離濾光器9，此處被分離之光經由全反射鏡1 1，1 2及 二向色反射鏡13，形成各色光i〇r(s)，KGO)，l〇B(s) 繼續經由偏光分束器2 R，2 G，2 B分別射入各反射型液晶 顯示裝置3R，3G，3B，各反射光因應反射型液晶顯示裝 置3R，3G，3B的施加電壓被偏光調制，再度射入偏光分 束器2R，2G，2B後，僅p偏光成分之光1〇R(p)，1〇G(p)， 1 〇B (p)透過，並以稜鏡4聚光。因此，由於使用該反射型 液晶顯示裝置之顯示，於施加電壓為零時，入射光直接作 為s偏光反射，因此形成不通過偏光分束器之所謂的正常 黑模式，於施加電壓上昇的同時被偏光調制，？偏光的反 射光增加，透過率上昇（參照圖14)。 使 上述論文①及②所報告之先 用之光學系統的F值在3.5以 文②中為3 · 5 )。光學系統之f值為 射光之取得角）Θ的函數，並以 前垂直配向液晶顯示裝置上 上（論文①中為3.8至4.8，論 &對裝 置之入射角 (=反 588193 ⑹ ·,*·······*·*············,*·*_·····················♦···············,········· 發明說明續耳 F = 1/(2 X sin 0 ) · · •公式 3 表示。F=3.5表示以裝置面之垂直方向為中心，以0± 8.2° 之角度内的光照明，而取得其反射光。 從上述公式3可知，由於F值小時，光之照射、取得角0 變大，因此總光束增加，亮度提高。但是，一般而言，反 射型液晶裝置之黑位準的數值（黑狀態下的透過率）於入射 角大時增加，且偏光分束器之偏光分離特性亦與0相關， 無法避免因Θ變大而惡化，因角度成分大造成p偏光成分 與s偏光成分的分離度降低。以致發生黑位準上昇對比大 幅降低的現象。 因而，在實用上須在亮度與對比上作取捨（兼顧困難 性），基於此，使用先前裝置之投影系統係使用F值（具體而 言為投影透鏡5之F值及照明光學系統之F值：以下均同）在 3.5以上的光學系統。亦即，使用先前裝置之投影光學系 統在實用上因要求實現某種程度的高對比，因此無法使F 值小於3.5，以致發生無法進一步提高亮度的問題。 因此，本發明之第一目的，在提供一種快速反應性之反 射型液晶顯示元件、使用該顯示元件之顯示裝置、投影光 學系統、及投影顯示系統，即使在垂直配向液晶顯示裝置 中，液晶層之厚度小，液晶透過率仍可以低電壓達到飽 和，即使係小像素尺寸，仍可以一般耐壓處理製造之驅動 電路基板輕易地驅動。 此外，本發明之第二目的，除上述第一目的之外，在提 供一種投影光學系統及投影顯示系統，即使係F值小之高 -12- 588193588193 发明 D. Description of the invention (The description of the invention should state: the technical field to which the invention belongs, the prior art, the content, the embodiments and the brief description of the drawings) TECHNICAL FIELD The present invention relates to a reflective liquid crystal (photoelectric) suitable for a projection display system and the like. ) Display element, display device used in combination with the display element, projection optical system, and projection display system. 2. Description of the Related Art In recent years, with the development of high-definition, miniaturization, and high-brightness projection display, the display device can also be miniaturized, high-definition, and reflective devices that can achieve high light utilization efficiency have attracted much attention and Has become practical. It is reported that, as opposed to a glass substrate formed with a transparent electrode, for example, a driving element is provided on a silicon substrate including a complementary metal oxide semiconductor (CMOS; Complementary Metal Oxide Semiconductor) circuit, and an aluminum light is arranged on the silicon substrate. A driving circuit substrate for a reflective electrode, an active reflective liquid crystal display device (element) in which a vertically aligned liquid crystal material is injected between the pair of substrates (thesis ①: H. Kurogane et al., Digests of SID 1998, P33-36 (1998 ), And paper ②: S. Uchiyama et al., Pr ceceings 〇f I dw 2 0 0 0, P 1 1 8 3 -1 1 8 4 (2000)), commercialization is actually formed by some manufacturers. Here, the so-called vertical alignment liquid crystal material refers to a material having a negative dielectric constant anisotropy (that is, a dielectric constant ε (||) parallel to a long axis of a liquid crystal molecule and a vertical dielectric constant ε (丄) Difference: Δε (= ε (||) _ ε (negative) liquid crystal material. When the applied voltage between the transparent electrode and the light-reflecting electrode is zero, the liquid crystal molecules are aligned approximately perpendicularly on the substrate surface, showing Normally black mode. 588193 (2) The thickness (cell gap) of the vertical alignment liquid crystal layer of the previous reflective device reported above is 3 ~ 4 μm, and the ratio of the driving voltage (the voltage applied to the liquid crystal) is The liquid crystal transmittance curve (hereinafter referred to as the VT curve, but because it is a reflective device, the actual measurement is equivalent to the reflectance of the device (however, as described later, the incident light such as s-polarized light is polarized by the device to obtain ρ-polarized light The reflected light.).) It has the characteristic of rising at a threshold voltage of about 2 V and reaching a maximum value at an applied voltage of 4 to 6 V. By changing the voltage during this time, the transmittance of the liquid crystal is changed analogously. , Can represent gray Figure 14 shows a data extracted from the above paper ①, which reports that the thickness of the liquid crystal layer is 3 μm, the driving voltage is about ± 4 V, and the reaction speed (rise time + fall time) is about 17 msec. Usually, the positive and negative voltages are driven in reverse in each frame or field. The above device actually means that it is driven with a maximum voltage of ± 4 ~ 6 V (Because the positive and negative VT curves are symmetrical in principle, the VT curve is usually only It is expressed as a positive value.) The liquid crystal driving voltmeter of ± 4 ~ 6 V is not effective for driving the transistor, but the voltage must be above 8 ~ 12 V. Because this is far greater than the withstand voltage of ordinary M 0 S processing, so A liquid crystal driving transistor formed in a pixel of a silicon driving circuit substrate is suitable for high withstand voltage treatment such as a lightly doped drain-source (LDD) structure. Considering manufacturing costs and power consumption, Its withstand voltage is usually 8 to 12 V. This is the reason why the previous devices were installed with a VT curve of a maximum of ± 4 to 6 V. In addition, the refractive index anisotropy Δη of the vertically aligned liquid crystal material used in the previous devices (I.e., with liquid The refractive index n (||) parallel to the major axis direction of the molecule 588193 (3) Description of the invention The difference between the refractive index n (丄) of the continuation sheet and its perpendicular direction: Δη (= η (||)-n (丄)) The value is less than 0.1 (typically about 0.08), and the typical pixel gap is 13.5 μm (pixel size 13 μm). In recent years, as is well known, the reaction speed of the shortcomings of liquid crystal display devices is particularly prominent. The problem of slowness is an important issue. In general, the reaction speed (rise time and fall time) of liquid crystal is shown in the following formulas 1 and 2, which is proportional to the square of the thickness d of the liquid crystal layer. Therefore, reducing the thickness of the liquid crystal layer helps to speed up. Rise time τ on γ -d2 £ (0) Ae (V2-Fc2) Formula 1 Fall time τ off = ..... Formula 2 (where: T: viscosity of liquid crystal, d: thickness of liquid crystal layer, Δ ε: Dielectric constant anisotropy of liquid crystal, ε (0): dielectric constant of vacuum, K: elastic constant of liquid crystal 'V · voltage applied to liquid crystal (liquid crystal driving voltage)' Vc · threshold voltage.) However, In the conventional vertical alignment liquid crystal display device, when the thickness of the liquid crystal layer is reduced, although the response speed is rapidly increased according to the formulas 1 and 2, there is a problem that the driving voltage required for saturation of the transmittance is increased. Figure 15 shows the V-T curve when the thickness of the liquid crystal layer is reduced in the system using the liquid crystal material (Δη = 0.082) used in the previous device. Figure 16 shows the change in saturation voltage due to the thickness d of the liquid crystal layer. As shown in Figures 15 and 16, the saturation voltage of the device rises sharply from the thickness of the liquid crystal layer d to about 2.5 μm and exceeds 6V. When d is less than 2 μm, it reaches 588193 (4) _____ to 10 volts. That is, the withstand voltage of the driving transistor also needs to be more than 20 volts. Moreover, when d is 1.5 μm thick or less, the absolute value of the transmittance does not reach 100%, and when 1 μm thick, not only the transmittance is only about 30%, but the threshold voltage is also increased. This phenomenon is because the vertical alignment liquid crystal becomes smaller with d (cell gap), the interaction between the liquid crystal molecules and the interface of the alignment film (Interaction), and the relative change of the orientation of the liquid crystal molecules to the director due to the applied voltage becomes larger. Conversely, when the thickness of the liquid crystal layer is large, due to the nature of the volume, the guide is easy to move, so that the influence of the interaction at the interface is reduced. As described above, when the driving voltage of a liquid crystal display device is increased, it is difficult to drive a general silicon driving element substrate. Of course, although it can be solved by increasing the financial pressure of the pixel driving transistor, in general such processing is complicated, which not only has high cost and large power consumption, but also increases the size of the transistor when the financial pressure is increased. Therefore, it is particularly difficult to produce such a highly resistant piezoelectric crystal with a small pixel size (or gap) of about 10 μm or less. Based on the above reasons, it is currently difficult to practically use a conventional reflective display device with vertically aligned liquid crystals to achieve a thickness of the liquid crystal layer of 2.5 μm or less. In addition, by reducing the thickness of the liquid crystal layer in this way, the reactivity to the applied voltage is also poor, and the yield of the device is reduced. Furthermore, the projection optical system using the above-mentioned previous device is shown below. In order to maintain high contrast, the F-number (F N u m be r) of the optical system must be 3.5 or more, and therefore a problem that the brightness cannot be improved occurs. A projection system using a reflective liquid crystal display device, as shown in Figure 17, needs to use polarized light for each color of red (R), green (G), and blue (B) through a polarizing separation device -10- 588193 (5) beam splitting Device 2 R, 2 G, 2 B, irradiates the light beam from lamp light source 1 on a reflection type liquid crystal display device 3 R, 3 G '3 B' using vertical alignment liquid crystal and synthesizes the light of each color (X-Cube Ii) 4 Reflects the polarized light modulated by these devices, and the projection light 10 (P) is projected onto the screen (not shown) through the projection lens 5 optical system. At this time, the illumination optical system of the illumination reflection type liquid crystal display device 3 R '3 G' 3 B is white light from the white lamp light source 1 (light 10 (P, s) where P polarized component and S polarized component are mixed). ), Through the fly-eye microlens 6, the polarization conversion device 7, the focusing lens 8, and the like, s-polarized light i0 (s) is formed, and is again guided to the dichroic separation filter 9, where the separated light passes through the total reflection mirror. 1 1, 12 and the dichroic mirror 13 form each color light iOR (s), KGO), and 10B (s) continue to enter each of them through the polarizing beam splitter 2 R, 2 G, and 2 B, respectively. Reflective liquid crystal display devices 3R, 3G, and 3B. Each reflected light is modulated by polarized light in response to the applied voltage of the reflective liquid crystal display devices 3R, 3G, and 3B. After being incident on the polarizing beam splitter 2R, 2G, and 2B again, only p-polarized components The light 10R (p), 10G (p), and 10B (p) were transmitted, and focused at 稜鏡 4. Therefore, since the display using the reflective liquid crystal display device, when the applied voltage is zero, the incident light is directly reflected as s-polarized light, so a so-called normal black mode that does not pass through the polarizing beam splitter is formed, and is applied while the applied voltage increases. Polarized light modulation? The reflected light of polarized light increases and the transmittance increases (see Fig. 14). Let the F value of the previously used optical system reported in the above papers ① and ② be 3.5 · in 3.5 and ②). The f value of the optical system is a function of the obtained angle of the incident light. ···············, * · * _ ··········· ♦♦ ·· ················ Description of the invention F = 1 / (2 X sin 0) · · • Formula 3 is expressed. F = 3.5 means device The vertical direction of the surface is taken as the center, and the reflected light is obtained by illuminating the light within an angle of 0 ± 8.2 °. As can be seen from the above formula 3, since the F value is small, the light irradiation and the acquisition angle 0 become larger, so the total light beam increases. In general, the black level value (transmittance in the black state) of the reflective liquid crystal device increases when the angle of incidence is large, and the polarization separation characteristic of the polarizing beam splitter is also related to 0, which cannot be Avoid deterioration due to the increase of Θ, and decrease in the separation between the p-polarized component and the s-polarized component due to the large angle component. As a result, the phenomenon that the black level rises and the contrast significantly decreases. Therefore, it is practical There must be a trade-off between brightness and contrast (taking into account the difficulty). Based on this, the projection system using the previous device uses the F value (specifically, the F value of the projection lens 5 and the F value of the illumination optical system: the same below) Optical system above 3.5. That is, the projection optical system using the previous device is practically required to achieve a certain degree of high contrast, so the F value cannot be less than 3.5, so that a problem that the brightness cannot be further improved occurs. Therefore, the present invention A first object of the present invention is to provide a reflective liquid crystal display element with fast reactivity, a display device using the display element, a projection optical system, and a projection display system. Even in a vertically aligned liquid crystal display device, the thickness of the liquid crystal layer is small. The liquid crystal transmittance can still reach saturation at a low voltage, and even with a small pixel size, it can still be easily driven by a driving circuit substrate manufactured by general withstand voltage processing. In addition, the second object of the present invention, in addition to the first object described above, Provide a projection optical system and projection display system, even if the F value is as small as -12-588193
⑺ 亮度光學系統，仍可維持極低的黑位準，在實用上實現高 對比（亦即，與先前之系統比較，兼具高亮度極高對比）。 發明之揭示⑺ The brightness optical system can still maintain a very low black level and achieve high contrast in practice (that is, compared with the previous system, it has both high brightness and extremely high contrast). Invention Revealed
亦即，本發明係有關一種反射型液晶顯示元件，其係具 有光透過性電極之第一基體、及具有光反射電極之第二基 體，在使前述光透過性電極及前述光反射電極彼此相對， 且藉有垂直配向液晶層的狀態下相對配置，前述垂直配向 液晶層之厚度在2 μιη以下，且垂直配向液晶材料之折射率 異方性Δη在0. 1以上（以下稱本發明之反射型液晶顯示元件 或裝置）者。此處，上述之所謂「光反射電極」，當然係指 電極本身具有光反射性之電極，不過，其定義亦包含在電 極上設置光反射層之電極，及即使電極具有光透過性，在 與底層膜之界面產生光反射性時，附此種底層膜的電極 (以下均同）。That is, the present invention relates to a reflective liquid crystal display element, which is a first substrate having a light-transmitting electrode and a second substrate having a light-reflecting electrode, and the light-transmitting electrode and the light-reflecting electrode are opposed to each other. 1 and relative arrangement in the state of the vertically aligned liquid crystal layer, the thickness of the aforementioned vertically aligned liquid crystal layer is below 2 μm, and the refractive index anisotropy Δη of the vertically aligned liquid crystal material is above 0.1 (hereinafter referred to as the reflection of the present invention Type liquid crystal display element or device). Here, the above-mentioned "light-reflecting electrode" refers to an electrode having a light-reflective property. However, the definition also includes an electrode having a light-reflective layer on the electrode, and even if the electrode has light-transmitting properties, When light reflection occurs at the interface of the underlying film, the electrodes of such underlying film are attached (the same applies hereinafter).
此外，本發明亦係有關具備本發明之反射型液晶顯示元 件（或裝置）之顯示裝置、在光程中配置有該反射型液晶顯 示元件之投影光學系統、及使用該光學系統之投影顯示系 統者。In addition, the present invention also relates to a display device including the reflective liquid crystal display element (or device) of the present invention, a projection optical system in which the reflective liquid crystal display element is arranged in the optical path, and a projection display system using the optical system. By.
依據本發明可知，即使減少垂直配向液晶層之厚度至2 μιη以下，與先前所瞭解的不同，藉由將垂直配向液晶材料 之Δη值提高，調整至0.1以上，液晶之透過率以5〜6V以下 的電壓即可輕易地飽和，可以實用性的低電壓驅動，此 外，透過率本身亦顯著提高。因此，可實現兼顧足夠之透 過率與低電壓驅動（低耐壓）的驅動特性，快速反應性佳之 -13 - 588193 ⑻ 反射型液晶顯示裝置、使用其之顯示裝置、投影光學系統 及投影顯示系統。 此種顯著之作用效果，尤其是藉由使用Δη高達0. 1以上之 垂直配向液晶材料可獲得。此因，為求快速反應而減少液 晶層之厚度在2 μπι以下時，即使因配向膜-液晶分子間之 相互作用而影響導向器的方向變化，由於提高An至0. 1以 上，入射光追隨施加電壓，在液晶中偏光調制容易，而容 易產生偏光分離，即使以低電壓仍可獲得所需的透過率。 再者，本發明亦係提供一種光程中配置有本發明之反射 型液晶顯示元件與F值在3以下之光學系統之投影光學系 統、及使用該光學系統之投影顯示系統者。 依據此等系統，由於減少垂直配向液晶層之厚度在2 μπι 以下，因此可抑制較低之與液晶層厚之二次方成正比的黑 位準，即使光學系統之F值在3以下，仍可實現高對比，且 可藉由小的F值同時實現高亮度。因此，可提供一種使用 本發明之反射型液晶元件裝置與F值在3以下之光學系統 之投影光學系統及顯示系統，與使用先前裝置與先前光學 系統之系統比較，同時滿足高對比與高亮度的系統。另 外，光學系統之F值可藉由使用之透鏡的焦點距離等控制。 圖式的簡單說明 圖1係改變反射型液晶顯不裝置之垂直配向液晶材料之 折射率異方性Δη時的V-T曲線圖（液晶層之厚度d為2 μπι 時）。 圖2係改變反射型液晶顯不裝置之垂直配向液晶材料之 •14- 588193 (9) 折射率異方性A n時的V - T曲線圖（液晶層之厚度d為1 . 5 μ m 時）。 圖3係改變反射型液晶顯示裝置之垂直配向液晶材料之 折射率異方性A η時的V - T曲線圖（液晶層之厚度d為1 μ m 時）。 圖4係顯示反射型垂直配向液晶顯示裝置之反應速度圖 (3 μιη及3·5 μπι厚度的試料係先前裝置的值）。 圖5係就各試料綜合顯示反射型液晶顯示裝置之垂直配 向液晶材料的厚度d、折射率異方性Δη及介電常數異方性 △ ε之飽和電壓、透過率及反應速度表。 圖6係顯示比較該裝置各液晶層厚d之液晶折射率異方 性Δη的飽和電壓變化圖。 圖7係該裝置之液晶層厚度為3 .5 μιη時，液晶之折射率 異方性Δη在0.13時的V-T曲線圖。 圖8係比較該裝置之黑狀態透過率與液晶層厚度之關係 (將先前裝置之液晶層厚度為3.5 μιη厚之裝置的黑狀態值 顯示為100%)圖。 圖9係比較本發明之反射型垂直配向液晶裝置與先前裝 置之黑位準因測定光學系統之F值的變化圖。 圖1 0係顯示本發明之亮度因F值的變化圖。 圖1 1係本發明之反射型垂直配向液晶顯示裝置的大致 剖面圖。 圖1 2係本發明之矽驅動電路基板側的重要部分剖面圖。 圖1 3係本發明裝置之佈局及等效電路圖。 -15- 588193 (ίο) 發明說明續頁 圖14係先前裝置的V-Τ曲線圖（液晶層之厚度約為3 μηι) 〇 圖15係先前裝置減少液晶層厚度時的V-Τ曲線圖（Δη為 0.082)。 圖1 6係顯示先前裝置之飽和電壓因液晶層厚的變化圖。 圖1 7係顯示使用先前反射型液晶顯示裝置之投影光學 系統的概要圖。 實施發明之最佳形態 本發明之反射型液晶顯示元件為獲得上述之作用效 果，其垂直配向液晶之層厚須在2 μηι以下，並宜為0.8〜2 μηι，更宜為1〜2μιη。厚度小者雖有助於快速反應，不過， 從與配向膜之相互作用的控制及層厚的控制性而言，其下 限宜為0.8μπι，更宜為Ιμιη。此外，液晶之層厚雖小，而 欲使偏光分離提高，Δη須在0.1以上，不過，過大並不能提 高其效果，且不符實用性，因此宜在0.2 5以下。 而在作為前述光透過性電極之氧化銦錫（ITO; Indium Tin Oxide)等透明電極及鋁等前述光反射電極的相對面上 分別形成有液晶配向膜，前述光反射電極可構成連接於前 述第二基體上設置之矽等單晶半導體驅動電路的主動驅 動型。第二基體使用矽驅動電路基板時，其本身為非透 明，且宜為反射型，並且可藉由半導體加工技術，將驅動 元件之金屬氧半導體（MOS; Metal Oxide Semiconductor) 電晶體及電壓供給用的輔助電容等予以高積體化成微細 圖案，因此可形成高開口率、因像素密度提高而高解像度 -16- 588193 (ii) 化、單元尺寸縮小，且可提高載體傳送速度。 實際上’驅動電路具備各像素設於石夕基板上之金屬氧半 導體場效電晶體（MOSFET ; Metal 〇xide Semiconductor Field Effect Transistor)等的驅動電晶體，該驅動電晶體之 輸出側連接有則述光反射電極。此外，為求可使用低電壓 驅動之低耐壓電晶體，因此像素尺寸可實現1〇 μπι以下。 液晶顯示裝置的尺寸亦可在對角為2时以下。 另外’前述垂直配向液晶材料之配向控制可藉由包含氧 化石夕膜的液晶配向膜來實施。此種配向膜可藉由具有方向 性（亦即液晶分子之預傾角控制容易）之真空蒸鍍法等形 成0 此外’具備本發明之反射型液晶顯示元件之顯示裝置、 及其液晶顯示元件（或進一步而言F值在3以下之光學***） 配置於光程中之投影光學及顯示系統，可在光程上配'置： 光源；使來自泫光源之光射入前述反射型液晶顯示元件之 光學系統，前述反射型液晶顯示元件；及導至來自該反射 型液晶顯示元件之反射光的光學系統。 此時，來自前述光源之光可通過偏光轉換元件及偏光分 束器，射入前述反射型液晶顯示元件，來自該反射型液1 顯示元件之反射光可再度通過前述偏光分束器被導至，Ζ 進一步導至投射透鏡及屏幕。 此外，可各色配置有前述反射型液晶顯示元件及前述偏 光分束器，來自各個反射型液晶顯示元件之反射光被聚 光，或進一步被導至前述投射透鏡。具體而言，來自白色According to the present invention, even if the thickness of the vertical alignment liquid crystal layer is reduced to less than 2 μm, it is different from the previous understanding. By increasing the Δη value of the vertical alignment liquid crystal material to be adjusted to more than 0.1, the transmittance of the liquid crystal is 5 to 6V. The following voltages can be easily saturated and can be driven by practical low voltages. In addition, the transmittance itself is significantly improved. Therefore, it is possible to achieve both sufficient transmittance and low-voltage driving (low withstand voltage) driving characteristics, and fast response. -13-588193 反射 Reflective liquid crystal display device, display device using it, projection optical system, and projection display system . Such a significant effect can be obtained, in particular, by using a vertical alignment liquid crystal material with Δη as high as 0.1 or more. For this reason, in order to reduce the thickness of the liquid crystal layer to less than 2 μm for fast response, even if the orientation of the director is affected by the interaction between the alignment film and the liquid crystal molecules, as the An is increased to 0.1 or more, the incident light follows. When a voltage is applied, polarization modulation is easy in the liquid crystal, and polarization separation is easy to occur. The required transmittance can be obtained even at a low voltage. Furthermore, the present invention also provides a projection optical system in which the reflective liquid crystal display element of the present invention and an optical system having an F value of 3 or less are arranged in the optical path, and a projection display system using the optical system. According to these systems, since the thickness of the vertically aligned liquid crystal layer is reduced to less than 2 μm, a lower black level that is proportional to the square of the liquid crystal layer thickness can be suppressed, even if the F value of the optical system is less than 3, High contrast can be achieved, and high brightness can be achieved simultaneously with a small F value. Therefore, it is possible to provide a projection optical system and a display system using the reflective liquid crystal element device of the present invention and an optical system with an F value of 3 or less, compared with a system using a previous device and a previous optical system, while meeting high contrast and high brightness system. In addition, the F-number of the optical system can be controlled by the focal length of the lens used. Brief Description of the Drawings Figure 1 is a V-T curve graph when the refractive index anisotropy Δη of the vertical alignment liquid crystal material of the reflective liquid crystal display device is changed (when the thickness d of the liquid crystal layer is 2 μm). Figure 2 shows the vertical alignment of a reflective liquid crystal display device. • 14- 588193 (9) V-T curve at the refractive index anisotropy An (when the thickness d of the liquid crystal layer is 1.5 μm ). FIG. 3 is a V-T curve when the refractive index anisotropy A η of the vertical alignment liquid crystal material of the reflective liquid crystal display device is changed (when the thickness d of the liquid crystal layer is 1 μm). FIG. 4 is a graph showing the response speed of a reflective vertical alignment liquid crystal display device (thickness samples of 3 μm and 3.5 μm are the values of the previous device). FIG. 5 is a table showing the saturation voltage, transmittance, and reaction rate of the thickness d, refractive index anisotropy Δη, and dielectric constant anisotropy Δε of the vertical alignment liquid crystal material of the reflective liquid crystal display device for each sample. Fig. 6 is a graph showing the change in saturation voltage of the liquid crystal refractive index anisotropy Δη of each liquid crystal layer thickness d of the device. Figure 7 is a V-T curve of the refractive index anisotropy Δη of the liquid crystal when the thickness of the liquid crystal layer of the device is 3.5 μm, at 0.13. Fig. 8 is a graph comparing the relationship between the black state transmittance of the device and the thickness of the liquid crystal layer (the black state value of a device with a liquid crystal layer thickness of 3.5 μm thick in the previous device is shown as 100%). Fig. 9 is a graph comparing the change of the F value of the black level-determining optical system of the reflective vertical alignment liquid crystal device of the present invention and the previous device. FIG. 10 is a graph showing a change in brightness factor F of the present invention. Fig. 11 is a schematic sectional view of a reflective vertical alignment liquid crystal display device of the present invention. FIG. 12 is a cross-sectional view of an important part of the silicon driving circuit substrate side of the present invention. Figure 13 is a layout and equivalent circuit diagram of the device of the present invention. -15- 588193 (ίο) Description of the invention Continued Figure 14 is the V-T curve of the previous device (the thickness of the liquid crystal layer is about 3 μηι) 〇 Figure 15 is the V-T curve of the previous device when the thickness of the liquid crystal layer is reduced ( Δη is 0.082). Fig. 16 is a graph showing the variation of the saturation voltage of the prior device due to the thickness of the liquid crystal layer. Fig. 17 is a schematic diagram showing a projection optical system using a conventional reflection type liquid crystal display device. Best Mode for Carrying Out the Invention In order to obtain the above-mentioned effect of the reflective liquid crystal display device of the present invention, the thickness of the vertically aligned liquid crystal layer must be 2 μm or less, preferably 0.8 to 2 μm, and more preferably 1 to 2 μm. Although the thickness is small, it contributes to rapid response, but from the point of control of the interaction with the alignment film and the controllability of the layer thickness, the lower limit should be 0.8 μm, and more preferably 1 μm. In addition, although the thickness of the liquid crystal layer is small, in order to increase the polarization separation, Δη must be 0.1 or more. However, too large a thickness does not improve its effect and is not practical, so it should be 0.2 5 or less. A liquid crystal alignment film is formed on the opposite surfaces of the transparent electrode such as indium tin oxide (ITO; Indium Tin Oxide) and the light reflecting electrode such as aluminum, and the light reflecting electrode may be connected to the first An active driving type of a single crystal semiconductor driving circuit such as silicon provided on two substrates. When a silicon substrate is used as the second substrate, the substrate itself is non-transparent and should be reflective. The semiconductor element can be used to supply metal oxide semiconductor (MOS; Metal Oxide Semiconductor) transistors and voltages through semiconductor processing technology. High-capacity auxiliary capacitors are formed into a fine pattern, so it can form a high aperture ratio, high resolution due to the increase in pixel density -16-588193 (ii), reduce the cell size, and improve the carrier transfer speed. In fact, the 'driving circuit' includes driving transistors such as metal oxide semiconductor field effect transistors (MOSFET; Metal Oxide Semiconductor Field Effect Transistor), each of which is provided on a shixi substrate. Light reflecting electrode. In addition, in order to use low-voltage piezoelectric crystals that can be driven with low voltage, the pixel size can be less than 10 μm. The size of the liquid crystal display device may be less than or equal to 2 when the diagonal is two. In addition, the aforementioned alignment control of the vertical alignment liquid crystal material can be implemented by a liquid crystal alignment film including an oxide film. Such an alignment film can be formed by a vacuum evaporation method or the like having directivity (that is, easy control of the pretilt angle of liquid crystal molecules). In addition, a display device including the reflective liquid crystal display element of the present invention, and its liquid crystal display element ( Or further speaking, an optical system with an F value of 3 or less) The projection optics and display system arranged in the optical path can be arranged on the optical path: a light source; the light that makes the light from the plutonium light source enter the aforementioned reflective liquid crystal display element System, the aforementioned reflective liquid crystal display element; and an optical system leading to reflected light from the reflective liquid crystal display element. At this time, the light from the aforementioned light source can pass through the polarization conversion element and the polarizing beam splitter to enter the aforementioned reflective liquid crystal display element, and the reflected light from the reflective liquid 1 display element can be guided to the aforementioned polarizing beam splitter again. , Z further leads to the projection lens and screen. In addition, the aforementioned reflective liquid crystal display elements and the aforementioned polarizing beam splitter may be arranged in each color, and the reflected light from each of the reflective liquid crystal display elements is focused or further guided to the aforementioned projection lens. Specifically, from white
-17- 588193 (12) _說明纘頁 光源之白色光通過前述偏光轉換元件，被導至二向色分離 據光器，此處被分離之光繼續於形成各色的分離光後，經 由前述偏光分束器，分別射入前述反射型液晶顯示元件， 各反射光以稜鏡聚光。 此處’與本發明之反射型液晶顯示元件組合使用之光學 系統的F值，為求兼具高對比與高亮度，須為3以下的較小 值，不過欲進一步提高其效果時，宜在3〇以下，15以上（更 宜在2 · 0以上）。 其次，參照圖式說明本發明適切的實施形態。 首先，構成本實施形態之顯示裝置之液晶光電元件的基 本構造顯示於圖1 1。 該裝置之反射型液晶顯示元件23包含··矽驅動電路基板 3 1 ’其係包含碎等單晶，該單晶設置具有像素構造的光反 射電極30 ;及與其相對之附透明電極32的破螭基板等透明 基板3 3 ;其間（實際上係於液晶配向膜3 4-3 5間）封入垂直配 向液晶36。如圖12所示，反射電極基板係在單晶矽基板37 上形成有包含CMOS及η通道MOS之電晶體Tr與包含電容 益C的驅動電路，在其上以鋁及銀等金屬膜形成像素狀的 光反射電極30，以構成驅動電路基板。為鋁等金屬光反射 電極時，可同時兼具光之反射膜及施加電壓於液晶上的電 極，不過，為求提高光反射率，亦可在鋁電極上形成電介 質反射鏡等多層膜的光反射層。 圖12中之電晶體τΓ如藉由η型源極區域38及汲極區域39 與閘極絕緣膜4 0及閘極4 1構成，自各主動區域分別取得電 •18- (13) ⑽193 (13) ⑽193 極 容 器 偏 壓 上 液 方 電 藏 描 電 助 驅 造 觀 設 現 加 時 2 其中電極4 3經由層間絕緣膜4 7，連接於構成電 杰C之η型區域44上之絕緣膜（電介質膜）連接的電容 電極46 ’並經由層間絕緣膜48，49 ,連接於配線50，進 ^連接於光反射電極3〇。而該裝置上，如圖I?所示之$ 光的入射光1 〇 (s )在垂直配向液晶3 6層中，因應施加電 而偏光轉換，擔^ 4異念r 传包含P偏光的反射光1〇 (p)，其被導至 述之偏光分束器2。 此處’該反射型液曰甚-- 主狄日日顯不70件依據本發明，其垂直配向 晶36之層厚（1(單元旭、、,， 、干間隙）在2 μιη以下，且使用折射率異 性Δ η在0. 1以上去从& 考作為垂直配向液晶3 6。 圖13顯示裝置之| σ 〈暴本佈局及像素部的等效電路。矽驅動 路基板•形成於各像素内之像素驅動電路；及内 於顯不區域周邊之邏輯部驅動器電路（資料驅動器、掃 驅動器等）。形成於各光反射（像素）電極3〇下之像素驅動 路由切換電晶體T r與供給電壓至垂直配向液晶3 6之輔 電容C構成。電晶體Tr上要求對應於垂直配向液晶36之 動電壓的耐壓，一般而言，係以高於邏輯的耐壓處理製 。隨形成高耐壓，電晶體之尺寸變大，且從成本與耗電 點而言，通常使用約8〜丨2 V之耐壓的電晶體，因此，宜 5十成液晶驅動電壓在士 6 γ以下，而依據本發明則可實 〇 本裝置使用之垂直配向液晶3 6 ’係藉由其分子長軸於施 電壓為零時配向成大致垂|於基板的方向’於施加電壓 對面内方向傾斜，使透過率變化者。驅動時，若液晶分 588193 (14) 子之傾斜方向不同，則產生明暗不一致，因此，為求避免， 如圖11所示，須在一定方向（一般而言為裝置的對角方向） 上預先賦予微小的預傾角，予以垂直配向。 預傾角過大時，垂直配向性惡化，黑位準上昇，致使對 比降低，而影響V-T曲線。因此，通常係控制預傾角在Γ 至7°之間。賦予該預傾角之液晶配向膜34，35，係使用氧 化矽等氧化矽薄膜之傾斜蒸鍍膜及聚醯亞胺膜，前者將傾 斜蒸鍍時之蒸鍍角度控制在如45°〜55Q，而後者藉由改變摩 擦條件，將上述預傾角控制在如1°〜7Q。 先前裝置使用圖11裝置構造之垂直配向液晶層的厚度d 約為3至4 μιη，折射率異方性An小於0. 1之值（典型而言約 為0.0 8)的垂直配向液晶材料。然而，先前裝置之液晶層厚 度d在2.5 μιη以下時，雖反應速度加快，但是如上所述， 驅動電壓提高，不適於實用裝置。因減少液晶層厚導致驅 動電壓上昇現象的機制雖尚未明確，係因層厚變厚的情況 下，主要出現液晶的整體性性質，而液晶層變薄時，則無 法忽略配向膜與液晶界面之兩者相互作用的影響（不使液 晶分子傾斜的作用）。 本發明人為求克服此種問題，反覆實施多次實驗結果發 現，藉由將垂直配向液晶材料之折射率異方性Δη之值提高 至0. 1以上，即可解決上述問題。圖1及圖2係顯示液晶層 厚度d為2μιη及1.5μπι時，改變液晶之Δη值時的V-T曲線變 化。從此等圖可知，即使使液晶層厚度d減少至2 μπι以下， 藉由使Δη在0.1以上，透過率以4〜6V以下的電壓即可輕易 -20- 588193 (15) 鞠_續買 達到飽和’可形成實用上的驅動。 且就連d = 1 μηι之極薄之液晶層厚的裝置，依據本發 明’如圖3所示，藉由使^在〇·〖以上，以約6 ν的驅動電壓 即大致飽和，且透過率亦顯著提高，先前裝置之材料構造 僅、勺3〇义。尤其藉由使用△!!=0.13之向Δη值的液晶材料， 即使為1 μηι厚度，仍可實現兼具足夠透過率與驅動特性的 矽反射型垂直配向液晶顯示裝置。 圖4顯示本發明之反射型液晶顯示裝置的反應速度（上 昇時間+下降時間）。與先前裝置比較非常快速，d = 2 μιη 厚時為7〜9 msec，1.5 μηι厚以下時為數msec以下（但是，d = 2.5 μιη厚時為13〜14 msec，反應速度不足）。再者，及二 1.5 μηι厚以下的裝置，即使是中間色調仍可保持8 mseca 下的快速反應。藉由本裝置，即使在中間色調顯示及動晝 多的影像及電視圖像上仍可實現不遜色的晝質。 圖5同時顯示本發明之裝置（試料ν〇· 7〜15)與比較試料 (試料No. 1〜6，16〜19)之各種特性，圖6顯示各種液晶層厚 d之飽和電壓因Δη的變化。從驅動特性、透過率及反應速 度的觀點，液晶層之厚度d在2μιη以下，尤其宜在 液晶之八11於2 0111厚時為厶11^〇.1(更宜為厶11^〇1〇3，最宜 為八11-〇.114)’於1.5 0111厚時為厶11-〇1〇6(更宜為^- 0.11，最宜為么11^0.114)及於1|11111厚時為么11^〇1〇4(更宜 為Δη 2 0.114 ’最宜為Δη ^ 〇.12)，在實用上特別適合。 因而，先前裝置之液晶層厚為3·5卜瓜時，使用具有Λη = 0· 1以上之高折射率異方性Δη的垂直配向液晶材料時，以^ -21 - 588193 (16) 發明說明續贾 =0. 1 3時為例，其V- T曲線顯示於圖7。從該圖可知，臨限 值電壓相當小，以約2 V的驅動電壓即達到飽和。但是， 如上述公式1所示，由於反應速度除液晶之層厚d以外，還 與驅動電壓的二次方成反比，因此此種低驅動電壓係導致 反應速度極低的因素。依據實際的測試，該裝置之黑白反 應速度為46 msec (約50 nsec)，再者，為中間色調時，反 映出驅動電壓更下降，亦接近100msec，可知欠缺實用性。 因而，從反應速度的觀點，先前裝置的Δη值宜小於0. 1。 如以上所述，本發明係新發現為實現液晶層厚度d在2 μ πι以下之反射型垂直配向液晶顯不裝置之液晶材料的△ η 值為必要條件者，即使液晶層厚d在2 μιη以下，藉由Δη g 0 . 1，可使飽和電壓降低，同時使反應速度提高。 另外，下列之表係綜合顯示上述各種Δη值（與Δε值）之垂 直配向液晶材料（此等均為MERUKU公司製）。 垂直配向液晶材料 試料A 試料B 试料C 試料D Δη +0.082 +0.103 +0.114 +0.13 η(||) 1.557 1.584 1.598 1.62 η(丄） 1.475 1.481 1.484 1.49 Δε -4.1 -5.0 -5.3 -4.3 ε(ΙΙ) 3.5 4.0 3.9 3.8 ε(丄） 7.6 9.0 9.2 8.1 其次，說明本發明之垂直配向液晶顯示裝置對F值比先 -22- 588193 發明說明纘頁 前裝置小的光學系統仍然有效。 首先顯示，發現本發明之液晶層厚薄之裝置的黑位準低 於先前之3〜4 μπι厚之裝置的結果。圖8顯示將本發明之垂 直配向液晶顯示裝置之黑位準的數值（電壓為零時之黑狀 態的透過率）作為液晶層厚的函數。各種材料係以3.5 μπι 厚的數值作為100%來表示（橫軸為液晶層的厚度）。 藉此，施加電壓為零時液晶分子係大致垂直於基板面配 向，因此，原理上入射光不改變偏光狀態而反射，並藉由 偏光分束器射回入射側，但實際的裝置藉由液晶分子預先 僅傾斜預傾角，因而稍微形成橢圓化，此外，如上所述， 由於偏光分束器的偏光分離特性與入射角相關，因此，藉 由此等，黑狀態下的透過率上昇，致使對比惡化。 但是，本發明之裝置的黑位準數值如圖8所示，於液晶 層厚愈薄時愈低，2 μιη厚的裝置，與先前裝置之厚度比較 為20〜3 0%，1 .5 μπι厚時為10〜20%，1 · 0 μπι厚時為5〜1 5 %(但 是，為2.5 μπι厚時則高達40〜50%)。對比係以白位準與黑 位準之比來表示，由於白位準大致相同，因此，於圖8的 結果顯示，本發明之裝置的對比如為1.5 μπι厚的裝置時， 提高5〜10倍以上。 因而，因減少液晶層厚導致黑位準數值降低的主要原因 如下。本裝置系統之液晶的透過率Τ以下列公式4表示： Τ 〇<= sin2 (2d · Δη (eff) · κ ! λ ) · ••公式 4 其中，λ為光的波長，Δη (eff)為因應液晶分子垂直方向 -23 - 588193 (18) 翻說明續夏 之倒角0之有效折射率異方性，並以下列公式5表示： Δη (eff) = ”(丨 1)7(.:9 ----------η(丄) · · •公式 5 7[/?(丨丨)2 · cos2 (0) + π(丄)2 · sin2(Θ)] 提高液晶之驅動電壓時，液晶分子之倒角0變大，因而 Δη (eff)增加，透過率提高。原理上可知0 = 90°時，Δη (eff) 等於液晶材料的Δη值。從公式4可知，透過率滿足2d · Δη (eff)· 7τ/λ = 7Γ/2的條件時，Τ=100%。 黑位準，亦即黑狀態的透過率於液晶分子完全垂直地配 向時（0 = 0)，Δη(είί*) = 0，黑狀態之透過率為零，不過實 際上如上所述，由於係附加約1〜7 °的預傾角來配向，因此 An(eff)為有限值，其賦予黑狀態的透過率。預傾角愈大， 黑狀態下之透過率上昇，因此更宜控制在5 °以下。黑位準 中，由於2d · Δη (eff) · 7Γ /久值小，因此，公式4近似性地 形成 T a sin2 (2d · Δη (eff) · 7Γ / 又）与（2d · Δη (eff) · 7Γ / 又）2，理 論上視為與液晶層厚d的二次方成正比。可知圖8所示之實 測資料大致可以此種關係說明。 因而，本裝置藉由將液晶層之厚度d設計較薄，在2 μιη 以下，與先前之3〜4 μιη厚的裝置比較，本質性地抑制低的 黑位準，可實現高對比。 如前述，先前裝置於減少光學系統之F值時，由於黑位 準上昇，無法確保對比，因此必須將F值設定在3.5以上， 而本發明之裝置如上所述，由於裝置單體之黑位準極低， 因此即使為F值小的光學系統仍可確保足夠的對比。 圖9顯示本發明之裝置改變對應於圖1 7之投射透鏡5及 -24- 588193 (19) _說明續頁 照明光學系統之測試光學系統之F值時黑狀態透過率的變 化。減少F值時，黑位準雖上昇，但是本發明之裝置不論F 值為何均可維持低於先前裝置的黑位準，因此即使為F值 小至3以下，仍可實現足夠的對比。且如圖1 0所示，由於F 值在3以下，亦有足夠的亮度（但是未達2時亮度飽和），F 值超過3時亮度降低。 有關亮度，從實驗可知，於實用之投影系統中，如對角 為0.7吋之裝置上使用120W之燈的光學系統，自F = 3.85變 成F = 2時，其亮度約提高60%。 如上所述，使用本發明之裝置及F值在3以下之光學系統 的投影光學系統及投影顯示系統，與使用先前裝置與先前 光學系統之系統比較，可提供同時滿足高對比與高亮度的 投影系統。 以下，具體說明本發明之實施例與比較例。 [比較例1 ] 製造如下之先前裝置。首先，洗淨形成有透明電極之玻 璃基板與形成有鋁電極之矽驅動電路基板後，導至蒸鍍裝 置内，以蒸鍍角度在45〜5 5°的範圍内，傾斜蒸鍍形成作為 液晶配向膜的氧化矽膜。並將液晶配向膜之膜厚控制在5 0 nm，液晶之預傾角控制在約2.5°。 之後，在形成有液晶配向膜之上述兩基板之間，僅以適 當數量散 1〜3.5 μπι直徑的玻璃珠，黏合兩者，注入 MERUKU公司製之介電常數異方性Δε為負，具有Δη = 0.0 8 2的垂直配向液晶材料，分別製造具有3.5 μπι、2.9 -25- 588193 (20) 翻說明纘頁 μιη、2·5 μιη、2 μιη、1·5 μπι及1 μιη之液晶層厚（單元間隙） 的六種反射型液晶顯示裝置（圖5之試料No. 1〜6)。 於此等裝置中，在透明電極與鋁電極之間施加電壓，測 試改變施加電壓時之液晶透過率的變化（由於為反射型， 因此實際上係測試裝置的反射率，但由於與測試液晶之透 過率等效，因此以下如此記載）。並在室溫下進行測試。 圖1 5顯示該液晶驅動特性。如圖1 5及圖1 6所示，液晶層 之厚度比2.5 μιη薄時，飽和驅動電壓急速上昇，並超過6 V。 [實施例1 ] 以比較例1相同的方法，製造在附透明電極基板與形成 有鋁電極的矽驅動電路基板上分別形成包含氧化矽膜的 液晶配向膜，在此等基板間注入MERUKU公司製之介電常 數異方性Δε為負，折射率異方性Δη為0.103、0.114及0.13 的三種垂直配向液晶材料，各材料具有2 μπι、1.5 μιη及1 jum 之液晶層厚度之合計九種反射型液晶顯示裝置（圖5之試 料No· 7〜15)。液晶之預傾角控制在約2.5°。 與比較例1同樣地在室溫下測試此等裝置的液晶驅動特 性。圖1、圖2及圖3分別顯示液晶層厚度為2 μιη、1 . 5 μιη 及1 μιη時的驅動特性。圖5綜合顯示各裝置之透過率大致 飽和時之驅動電壓與其透過率之值。 從該結果可知，即使減少液晶層厚度d至2 μπι以下，藉 由使A η在0 . 1以上，透過率以4〜6 V以下的電壓即可輕易地 達到飽和，可形成實用性的驅動。且由於透過率亦比先前 -26- 588193 (21) 發明說明續頁 裝置大幅提高，因此可實現具有足夠透過率與驅動特性的 矽反射型垂直配向液晶顯示裝置。 另外亦製造使用聚醯亞胺膜以取代氧化矽膜，作為液晶 配向膜，以摩擦配向控制的裝置，不過，其結果與上述相 同。 [實施例2]-17- 588193 (12) _Explanation that the white light of the title page light source is led to the dichroic separation light receiver through the aforementioned polarization conversion element, and the separated light here continues to form the separated light of each color and then passes through the aforementioned polarized light The beam splitter is incident on the reflective liquid crystal display element, and each reflected light is condensed by chirp. Here, the F value of the optical system used in combination with the reflective liquid crystal display element of the present invention must be a small value of 3 or less in order to achieve both high contrast and high brightness. However, if the effect is to be further improved, it is preferable to Below 30 and above 15 (more preferably above 2.0). Next, a suitable embodiment of the present invention will be described with reference to the drawings. First, the basic structure of a liquid crystal photovoltaic element constituting the display device of this embodiment is shown in FIG. The reflection type liquid crystal display element 23 of the device includes a silicon driving circuit substrate 3 1 ′, which includes a single crystal such as a chip, and the single crystal is provided with a light reflection electrode 30 having a pixel structure; A transparent substrate 3 3 such as a substrate; a vertical alignment liquid crystal 36 is sealed between them (actually, between the liquid crystal alignment films 3 4-3 5). As shown in FIG. 12, the reflective electrode substrate is formed on a single-crystal silicon substrate 37 with a transistor Tr including CMOS and n-channel MOS and a driving circuit including capacitor C, and a pixel is formed thereon with a metal film such as aluminum and silver. The light-reflecting electrode 30 in a shape constitutes a driving circuit board. When it is a metal light reflection electrode such as aluminum, it can have both a light reflection film and an electrode that applies a voltage to the liquid crystal. However, in order to improve the light reflectivity, a multilayer film such as a dielectric mirror can also be formed on the aluminum electrode. Reflective layer. The transistor τΓ in FIG. 12 is composed of an n-type source region 38 and a drain region 39, and a gate insulating film 40 and a gate 41, and electricity is obtained from each active region. 18- (13) ⑽193 (13 ) ⑽ 193-pole container biased on the liquid side of the electric reservoir to assist in the creation of the drive time 2 in which the electrode 4 3 through the interlayer insulating film 4 7 is connected to the n-type region 44 constituting the electric film C (dielectric film) ) The connected capacitor electrode 46 ′ is connected to the wiring 50 via the interlayer insulating films 48 and 49, and is further connected to the light reflection electrode 30. On this device, as shown in Fig. I ?, the incident light 1 〇 (s) in the vertical alignment liquid crystal 36 layer, the polarization conversion in response to the application of electricity, ^ 4 different ideas r pass including the reflection of P polarization Light 10 (p) is directed to the polarizing beam splitter 2 described above. Here, the reflection type liquid is very much-the main Dili Rixian 70 pieces according to the present invention, the thickness of the vertical alignment crystal 36 (1 (unit Asahi ,,,,, dry gap) is less than 2 μm, and The refractive index anisotropy Δ η is more than 0.1 to be used as a vertical alignment liquid crystal 3 6. Fig. 13 shows the display device | σ 〈equivalent layout and pixel equivalent circuit. The silicon driver circuit substrate is formed in each Pixel driving circuit in the pixel; and logic part driver circuits (data driver, scan driver, etc.) in the periphery of the display area. The pixel driving route formed under each light reflection (pixel) electrode 30 switches the switching transistor T r and The auxiliary capacitor C, which supplies the voltage to the vertically aligned liquid crystal 36, is required. The transistor Tr requires a withstand voltage corresponding to the dynamic voltage of the vertically aligned liquid crystal 36. Generally, it is made with a higher withstand voltage than logic. Withstand voltage, the size of the transistor becomes larger, and in terms of cost and power consumption, usually with a voltage of about 8 to 2 V, so 50% of the liquid crystal drive voltage should be less than ± 6 γ, According to the present invention, the device can be implemented. The vertical alignment liquid crystal 3 6 'is aligned by its molecular long axis when the applied voltage is zero. The direction of the substrate is inclined to the in-plane direction when the applied voltage is inclined, so that the transmittance changes. 588193 (14) If the tilt direction of the son is different, the brightness and darkness will be inconsistent. Therefore, to avoid it, as shown in Figure 11, a small pretilt angle must be given in a certain direction (generally the diagonal direction of the device). When the pretilt angle is too large, the vertical alignment deteriorates, the black level rises, causing the contrast to decrease, and affecting the VT curve. Therefore, the pretilt angle is usually controlled between Γ and 7 °. The liquid crystal alignment that gives the pretilt angle Films 34 and 35 are tilted vapor-deposited films using silicon oxide films such as silicon oxide, and polyimide films. The former controls the evaporation angle during tilted deposition to 45 ° ~ 55Q, while the latter changes friction conditions by The pre-tilt angle is controlled to be 1 ° ~ 7Q. The thickness of the vertically aligned liquid crystal layer d of the previous device using the device of FIG. 11 is about 3 to 4 μιη, and the refractive index anisotropy An is less than 0.1 value (typically The vertical alignment liquid crystal material is 0.0 8). However, when the thickness d of the liquid crystal layer of the previous device is less than 2.5 μm, the response speed is accelerated, but as mentioned above, the driving voltage is increased, which is not suitable for practical devices. It is caused by reducing the thickness of the liquid crystal layer. Although the mechanism of the driving voltage rise phenomenon has not yet been clarified, because the layer thickness becomes thicker, the integral properties of the liquid crystal mainly appear, and when the liquid crystal layer becomes thin, the influence of the interaction between the alignment film and the liquid crystal interface cannot be ignored. (The effect of not tilting the liquid crystal molecules). In order to overcome this problem, the inventors repeatedly carried out experimental results and found that by increasing the value of the refractive index anisotropy Δη of the vertically aligned liquid crystal material to 0.1 or more, The above problem can be solved. Figures 1 and 2 show the changes in the V-T curve when the Δη value of the liquid crystal is changed when the thickness d of the liquid crystal layer is 2 µm and 1.5 µm. From these figures, it can be seen that even if the thickness d of the liquid crystal layer is reduced to less than 2 μm, by making Δη above 0.1 and the transmittance at a voltage of 4 to 6V, it is easy to -20- 588193 (15) 'Can form a practical drive. Moreover, even a device with an extremely thin liquid crystal layer of d = 1 μηι, according to the present invention, as shown in FIG. 3, by making ^ above 〇 · 〖, a driving voltage of about 6 ν is approximately saturated, and transmits The rate is also significantly improved. The material structure of the previous device is only 30 millimeters. In particular, by using a liquid crystal material having a Δη value of Δ !! = 0.13, a silicon reflective vertical alignment liquid crystal display device having sufficient transmittance and driving characteristics can be realized even with a thickness of 1 μm. Fig. 4 shows the response speed (rise time + fall time) of the reflective liquid crystal display device of the present invention. Compared with the previous device, it is very fast, 7 to 9 msec when d = 2 μm thick and several msec or less when 1.5 μm thick or less (however, 13 to 14 msec when d = 2.5 μm thick, the reaction speed is insufficient). Furthermore, with devices less than 1.5 μm thick, fast response at 8 mseca can be maintained even with midtones. With this device, the daylight quality is not inferior even in the mid-tone display and the images and TV images with many daylight. Fig. 5 shows various characteristics of the device of the present invention (samples ν〇 · 7 ~ 15) and comparative samples (samples No. 1 to 6, 16 to 19) at the same time. Fig. 6 shows the saturation voltage due to the Δη of various liquid crystal layer thicknesses d Variety. From the viewpoint of driving characteristics, transmittance, and reaction speed, the thickness d of the liquid crystal layer is 2 μm or less, and is particularly preferably 厶 11 ^ 〇.1 (more preferably 厶 11 ^ 〇1〇) when the thickness of the liquid crystal is 11 to 2 0111. 3, most preferably 8 11-〇.114) 'at 1.5 0111 thickness is 厶 11-〇1〇6 (more preferably ^ -0.11, most preferably 11 ^ 0.114) and at 1 | 11111 thickness Then 11 ^ 〇104 (more preferably Δη 2 0.114 ', most preferably Δη ^ 〇.12) is particularly suitable for practical use. Therefore, when the thickness of the liquid crystal layer of the previous device is 3.5, the vertical alignment liquid crystal material having a high refractive index anisotropy Δη of Λη = 0.1 or more is used. ^ -21-588193 (16) Description of the invention Continued Jia = 0. 1 3 as an example, the V-T curve is shown in Figure 7. As can be seen from the figure, the threshold voltage is quite small, and it reaches saturation with a driving voltage of about 2 V. However, as shown in the above formula 1, since the reaction speed is inversely proportional to the second power of the driving voltage in addition to the thickness d of the liquid crystal, such a low driving voltage causes a very low reaction speed. According to actual tests, the black and white response speed of this device is 46 msec (approximately 50 nsec). In addition, when it is halftone, it reflects that the driving voltage has dropped even closer to 100 msec, which shows that it lacks practicality. Therefore, from the viewpoint of reaction speed, the Δη value of the previous device should be less than 0.1. As described above, the present invention is a new discovery in which the value of the Δ η of the liquid crystal material of a reflective vertical alignment liquid crystal display device with a liquid crystal layer thickness d of 2 μ π or less is necessary, even if the liquid crystal layer thickness d is 2 μ η Hereinafter, Δη g 0.1 can reduce the saturation voltage and increase the reaction speed. In addition, the following tables show the vertical alignment liquid crystal materials of the above various Δη values (and Δε values) (these are all manufactured by MERUKU). Vertical alignment liquid crystal material sample A sample B sample C sample D Δη +0.082 +0.103 +0.114 +0.13 η (||) 1.557 1.584 1.598 1.62 η (丄) 1.475 1.481 1.484 1.49 Δε -4.1 -5.0 -5.3 -4.3 ε ( II) 3.5 4.0 3.9 3.8 ε (丄) 7.6 9.0 9.2 8.1 Secondly, the vertical alignment liquid crystal display device of the present invention will be described to be effective for an optical system having a smaller F value than the previous -22-588193 invention description. First, it is shown that the black level of the device with a thin liquid crystal layer according to the present invention is lower than that of the previous device with a thickness of 3 to 4 μm. Fig. 8 shows the value of the black level (transmittance of the black state when the voltage is zero) of the vertical alignment liquid crystal display device of the present invention as a function of the thickness of the liquid crystal layer. For each material, a value of 3.5 μm thick is taken as 100% (the horizontal axis is the thickness of the liquid crystal layer). As a result, the liquid crystal molecules are aligned approximately perpendicular to the substrate surface when the applied voltage is zero. Therefore, in principle, incident light is reflected without changing the polarization state and is returned to the incident side by a polarizing beam splitter. However, the actual device uses liquid crystal The molecules are only tilted by the pretilt angle in advance, so that they become slightly elliptical. In addition, as described above, the polarization separation characteristics of the polarizing beam splitter are related to the angle of incidence. As a result, the transmittance in the black state increases, resulting in a contrast. deterioration. However, the black level value of the device of the present invention is as shown in FIG. 8, which is lower as the thickness of the liquid crystal layer is thinner. For a device with a thickness of 2 μm, compared with the thickness of the previous device, it is 20 ~ 30%, 1.5 μm. 10 to 20% when thick, and 5 to 15% when 1.0 μm thick (however, up to 40 to 50% when 2.5 μm thick). The contrast is expressed by the ratio of the white level to the black level. Since the white level is approximately the same, the result shown in FIG. 8 shows that when the device of the present invention is 1.5 μm thick, it is increased by 5 to 10. Times more. Therefore, the main reasons for the decrease in the black level value due to the reduction in the thickness of the liquid crystal layer are as follows. The transmittance T of the liquid crystal of the device system is expressed by the following formula 4: Τ 〈= sin2 (2d · Δη (eff) · κ! Λ) · •• Formula 4 where λ is the wavelength of light and Δη (eff) In order to respond to the vertical direction of the liquid crystal molecules -23-588193 (18), we will explain the effective refractive index anisotropy of the chamfer 0 of the summer, and use the following formula 5: Δη (eff) = ”(丨 1) 7 (.: 9 ---------- η (丄) · · • Equation 5 7 [/? (丨 丨) 2 · cos2 (0) + π (丄) 2 · sin2 (Θ)] Improve the driving of liquid crystal At voltage, the chamfer 0 of the liquid crystal molecules becomes larger, so Δη (eff) increases, and the transmittance increases. In principle, it can be known that when 0 = 90 °, Δη (eff) is equal to the Δη value of the liquid crystal material. From Equation 4, we can know that the transmittance When the conditions of 2d · Δη (eff) · 7τ / λ = 7Γ / 2 are satisfied, T = 100%. The black level, that is, the transmittance of the black state when the liquid crystal molecules are completely vertically aligned (0 = 0), Δη (είί *) = 0, the transmittance of the black state is zero, but in fact, as mentioned above, because a pretilt angle of about 1 ~ 7 ° is added to align, An (eff) is a finite value, which gives the black state Transmittance. The greater the pretilt angle, the darker In the black state, the transmittance is increased, so it is more suitable to control it below 5 °. In the black level, since 2d · Δη (eff) · 7Γ / long value is small, Equation 4 approximately forms T a sin2 (2d · Δη (eff) · 7Γ / again) and (2d · Δη (eff) · 7Γ / again) 2 are theoretically considered to be proportional to the square of the thickness d of the liquid crystal layer. It can be seen that the measured data shown in Figure 8 can be roughly this. Therefore, by designing the thickness d of the liquid crystal layer to be thinner than 2 μm, compared with the previous device with a thickness of 3 to 4 μm, this device can substantially suppress the low black level and achieve high Contrast. As mentioned above, when the previous device reduces the F value of the optical system, the contrast cannot be ensured because the black level rises. Therefore, the F value must be set to 3.5 or more. The device of the present invention is as described above. The black level is extremely low, so sufficient contrast can be ensured even with an optical system with a small F value. Figure 9 shows that the device of the present invention changes corresponding to the projection lenses 5 and -24-588193 of Figure 17 (19) _Explanation continued Test of the optical system of the page illumination optical system The change of the overrate. When the F value is reduced, the black level rises, but the device of the present invention can maintain the black level lower than the previous device regardless of the F value, so it can be achieved even if the F value is less than 3 Sufficient contrast. As shown in Figure 10, because the F value is below 3, there is also sufficient brightness (but the brightness is saturated when it is less than 2), and the brightness decreases when the F value exceeds 3. With regard to brightness, it can be known from experiments that in a practical projection system, such as an optical system using a 120W lamp on a device with a diagonal of 0.7 inches, when F = 3.85 is changed to F = 2, its brightness is increased by about 60%. As described above, the projection optical system and projection display system using the device of the present invention and an optical system with an F value of 3 or less can provide a projection that satisfies both high contrast and high brightness compared with a system using a previous device and a previous optical system. system. Hereinafter, examples and comparative examples of the present invention will be specifically described. [Comparative Example 1] The following conventional device was manufactured. First, the glass substrate on which the transparent electrode is formed and the silicon drive circuit substrate on which the aluminum electrode is formed are washed, and then led into a vapor deposition device, and the liquid crystal is formed by oblique vapor deposition at a vapor deposition angle within a range of 45 to 55 °. Silicon oxide film for alignment film. The thickness of the liquid crystal alignment film is controlled at 50 nm, and the pretilt angle of the liquid crystal is controlled at about 2.5 °. After that, between the two substrates on which the liquid crystal alignment film is formed, only a suitable number of glass beads with a diameter of 1 to 3.5 μm are dispersed, and the two are bonded, and the dielectric constant anisotropy Δε manufactured by MERUKU is negative and has Δη. = 0.0 8 2 vertical alignment liquid crystal material to produce liquid crystal layer thicknesses of 3.5 μπι, 2.9 -25- 588193 (20) flip sheet μιη, 2 · 5 μιη, 2 μιη, 1.5 μιη, and 1 μιη, respectively ( Cell gap) of six types of reflective liquid crystal display devices (Sample Nos. 1 to 6 of Fig. 5). In these devices, a voltage is applied between the transparent electrode and the aluminum electrode to test the change in the transmittance of the liquid crystal when the voltage is changed (because it is reflective, it is actually the reflectance of the test device, but because The transmittance is equivalent, so it is described below). And tested at room temperature. Figure 15 shows the liquid crystal driving characteristics. As shown in Fig. 15 and Fig. 16, when the thickness of the liquid crystal layer is thinner than 2.5 μm, the saturation driving voltage rises rapidly and exceeds 6 V. [Example 1] In the same manner as in Comparative Example 1, a liquid crystal alignment film including a silicon oxide film was formed on a substrate with a transparent electrode and a silicon drive circuit substrate formed with an aluminum electrode, and a substrate made by MERUKU was injected between these substrates. Three kinds of vertical alignment liquid crystal materials with negative dielectric anisotropy Δε and refractive index anisotropy Δη of 0.103, 0.114, and 0.13, each material has a total of nine reflections of a liquid crystal layer thickness of 2 μm, 1.5 μm, and 1 jum Type liquid crystal display device (sample Nos. 7 to 15 in Fig. 5). The pretilt angle of the liquid crystal is controlled at about 2.5 °. As in Comparative Example 1, the liquid crystal driving characteristics of these devices were tested at room temperature. FIG. 1, FIG. 2 and FIG. 3 show the driving characteristics when the thickness of the liquid crystal layer is 2 μm, 1.5 μm, and 1 μm, respectively. Figure 5 shows the drive voltage and its transmittance when the transmittance of each device is approximately saturated. From this result, it can be seen that even if the thickness d of the liquid crystal layer is reduced to 2 μm or less, the saturation can be easily reached with a voltage of 4 to 6 V or less by setting A η to 0.1 or more, and practical driving can be formed. . And because the transmittance is also much higher than the previous -26- 588193 (21) Invention Description Continuation Device, a silicon reflective vertical alignment liquid crystal display device with sufficient transmittance and driving characteristics can be realized. In addition, a device using a polyimide film instead of a silicon oxide film as a liquid crystal alignment film and controlling frictional alignment is also manufactured, but the results are the same as those described above. [Example 2]
測試實施例1所製造之反射型液晶顯示裝置之上昇（自 黑至白）及下降（自白至黑）的反應速度。將其總和作為裝置 的反應速度，圖5顯示其結果。並在室溫下進行測試。圖4 顯示代表例為An = 0. 1 3之裝置時（圖5之試料N 〇. 9，1 2， 1 5，及d二2.5 μιη之試料），將液晶層的厚度作為函數。此 外，比較例亦顯示先前例之試料Ν ο · 1與以3 μιη厚製造之 試料（均為An = 0.08 2)的反應速度。The reflective liquid crystal display device manufactured in Example 1 was tested for rising (from black to white) and falling (from white to black) response rates. The total is taken as the reaction speed of the device, and the results are shown in Fig. 5. And tested at room temperature. Fig. 4 shows a representative example of an apparatus with An = 0.13 (samples No. 0.9, 12, 15, and d = 2.5 μm in Fig. 5), using the thickness of the liquid crystal layer as a function. In addition, the comparative example also shows the reaction speed of the sample Ν · · 1 of the previous example and the sample (both An = 0.08 2) manufactured in a thickness of 3 µm.
反應速度如從上述公式1，2所推測，係與液晶層之厚度 的大致二次方成正比變化，而由於本發明之裝置之液晶層 厚度d在2 μιη以下，Δη在0.1以上，因此證明可實現9 msec 以下的快速反應。 [比較例2 ]The reaction rate, as inferred from the above formulas 1,2, varies in proportion to the approximate square of the thickness of the liquid crystal layer, and since the thickness d of the liquid crystal layer of the device of the present invention is 2 μm or less and Δη is 0.1 or more, it is proved that Achieve quick response below 9 msec. [Comparative Example 2]
以實施例1相同的方法製造使用An = 0 · 1 3之液晶材料， 層厚為3.5 μιη的反射型液晶顯示裝置（試料No. 16)，探討 液晶驅動特性。 圖7顯示其結果與Δη = 0.082時（試料No. 1)比較，該裝置 的驅動電壓極低。此外，與實施例2同樣地測試在室溫下 之反應速度的結果，反應速度為46 msec。由於驅動電壓 -27- 588193 (22) 奋明說麟:績貢： 為1 V，因此中間色調更緩慢，2 5 %之灰階上的反應速度接 近 1 0 0 m s e c 〇 [實施例3 ] 測試實施例1所製造之反射型液晶顯示裝置之施加電壓 為零（黑狀態）時的透過率（黑位準）。為求有系統地探討黑 位準對液晶層厚度的變化，以各Δη的試料製造先前裝置之 層厚為3.5 μπι之裝置（圖5之試料No. 17〜19)及層厚為2.5 μιη之裝置，並與實施例1之試料（試料No· 7〜15)同時測試。 圖8係顯示各個Δη之試料，將3.5 μπι厚之裝置的數值作為 10 0%，顯示黑位準的數值。 如圖8所示，各個An的試料，均發現減少液晶層厚度在2 μ m以下時，黑位準顯著降低，如1 . 5 μ m厚的裝置比3 · 5 μ m 厚之裝置的數值，顯示低10〜2 0%的黑位準。亦即，顯示裝 置之對比達5〜1 0倍。圖7之測試光學系統的F值為3 · 8 5，不 過，即使改變F值，此種情形大致相同。 [實施例4 ] 將實施例1之An = 0.13，液晶層厚1.5 μιη，2.0 μιη之裝置 (試料No. 12，9)設置在F值為3.85，3及2的測試光學系統 内，將裝置之黑位準（黑狀態之透過率）與先前裝置（試料No _ 1)比較。 圖9顯示其結果。黑位準因F值降低而上昇，但是本發明 之裝置，不論何種F值，均維持低於先前裝置的黑位準。 各裝置之白位準的透過率約為〇 · 6，且大致相同。因此，黑 位準之比直接賦予裝置的對比之比，可知本發明之裝置， -28- 588193 (23) 發明說明績頁 即使為F值小至3以下的光學系統，仍可實現與先前裝置相 等或大於的對比。該F值的下限宜為1 . 5，更宜為2.0。 此外，以上述相同的規格製造對角為0.7吋之矽反射型垂 直配向液晶顯示裝置，使用120W之燈光源，以F值=3.85， 3.5，3，2.5及2的實用投影光學系統比較亮度，如圖1 0所 示，對應於F值=3 . 8 5之光學系統的亮度值，F值=3約提 高3 2 %，F值=2.5約提高4 4 %，F值=2約提高6 0 %，F值S 3 時大幅提高。但是，F值=3 . 5時，僅提高約1 5 %，此外，F 值==1 . 5時，與F值=2並無太大變動。對比如上所述，即 使為F值$ 3的光學系統，仍維持高於先前裝置之對比的高 對比。亦即，比先前裝置可實現同時提高亮度與對比的投 影系統。 以上所述之本發明的實施形態及實施例，依據本發明之 技術構想可作各種改變。 例如，上述之反射型液晶顯示元件及使用其之光學或投 影系統之構成部分的構造及材質等，並不限定於上述者， 可作各種改變。 如以上所述，依據本發明，即使垂直配向液晶層之厚度 小至2 μπι以下，藉由將垂直配向液晶材料之Δη的值提高至 0. 1以上，液晶之透過率以5〜6 V的電壓即可輕易地達到飽 和，可以實用性的低電壓驅動，且透過率本身亦顯著提 高。因此，可實現具有足夠透過率與低電壓驅動（低耐壓） 之驅動特性，快速反應佳之反射型垂直配向液晶顯示裝 置、使用其之顯示裝置、投影光學及顯示系統。 -29-In the same manner as in Example 1, a reflective liquid crystal display device (Sample No. 16) using a liquid crystal material of An = 0.13 and a layer thickness of 3.5 μm was manufactured, and the liquid crystal driving characteristics were examined. Fig. 7 shows the results when compared with Δη = 0.082 (Sample No. 1), the driving voltage of this device is extremely low. The reaction rate at room temperature was measured in the same manner as in Example 2. The reaction rate was 46 msec. Because the driving voltage is -27- 588193 (22) Fen Ming said Lin: Ji Gong: It is 1 V, so the intermediate tone is slower, and the response speed on the gray scale of 25% is close to 100 msec. [Example 3] Test implementation The transmittance (black level) when the applied voltage of the reflective liquid crystal display device manufactured in Example 1 was zero (black state). In order to systematically explore the change of the black level to the thickness of the liquid crystal layer, a device with a layer thickness of 3.5 μm (sample No. 17 to 19 in FIG. 5) and a layer thickness of 2.5 μm were prepared from each sample of Δη. The device was tested simultaneously with the sample (Sample Nos. 7 to 15) of Example 1. Fig. 8 shows each sample of Δη. The value of a device with a thickness of 3.5 μm is taken as 100%, and the value of the black level is shown. As shown in Figure 8, for each An sample, it is found that when the thickness of the liquid crystal layer is reduced below 2 μm, the black level is significantly reduced. For example, a device with a thickness of 1.5 μm is larger than a device with a thickness of 3.5 μm , Showing a low black level of 10 to 20%. That is, the contrast ratio of the display devices is 5 to 10 times. The F value of the test optical system in Fig. 7 is 3 · 8 5. However, even if the F value is changed, the situation is about the same. [Example 4] An apparatus (An = 0.13, liquid crystal layer thickness 1.5 μm, 2.0 μm) of Example 1 (Sample No. 12, 9) was set in a test optical system with F values of 3.85, 3, and 2. The black level (transmittance in the black state) is compared with the previous device (sample No. 1). Figure 9 shows the results. The black level rises as the F value decreases, but the device of the invention, regardless of the F value, remains lower than the black level of the previous device. The white level transmittance of each device is approximately 0.6, and is approximately the same. Therefore, the ratio of the black level directly gives the ratio of the device. It can be seen that the device of the present invention, -28- 588193 (23) Invention description page can be achieved even with an optical system with an F-number as low as 3 or less. Equal or greater contrast. The lower limit of the F value should be 1.5, more preferably 2.0. In addition, a silicon reflective vertical alignment liquid crystal display device with a diagonal of 0.7 inches is manufactured with the same specifications as described above, and a 120W lamp light source is used, and the practical projection optical system with F value = 3.85, 3.5, 3, 2.5 and 2 is used to compare the brightness. As shown in Fig. 10, corresponding to the brightness value of the optical system with F value = 3. 8 5, F value = 3 is increased by about 3 2%, F value = 2.5 is increased by about 4 4%, and F value = 2 is increased by about 6 0%, the F value is greatly increased at S3. However, when F value = 3.5, the increase is only about 15%. In addition, when F value == 1.5, there is not much change from F value = 2. The contrast is as described above, and even the optical system with an F value of $ 3 maintains a high contrast higher than that of the previous device. That is, a projection system capable of simultaneously improving brightness and contrast can be realized as compared with the previous devices. The embodiments and examples of the present invention described above can be variously modified in accordance with the technical concept of the present invention. For example, the structures and materials of the above-mentioned reflective liquid crystal display elements and the components of optical or projection systems using the same are not limited to the above, and various changes can be made. As described above, according to the present invention, even if the thickness of the vertically aligned liquid crystal layer is as small as 2 μm or less, by increasing the value of Δη of the vertically aligned liquid crystal material to 0.1 or more, the transmittance of the liquid crystal is 5 to 6 V. The voltage can easily reach saturation, can be driven by practical low voltage, and the transmittance itself is significantly improved. Therefore, a reflective vertical alignment liquid crystal display device with sufficient transmittance and low-voltage driving (low withstand voltage) driving characteristics, and fast response can be realized, a display device using the same, projection optics, and a display system. -29-
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| JP2002181945A JP3758612B2 (en) | 2001-06-26 | 2002-06-21 | Reflective liquid crystal display device, display device, projection optical system, and projection display system |
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| WO2003001285A1 (en) | 2001-06-26 | 2003-01-03 | Sony Corporation | Reflection type liquid crystal display element, display unit, projection optical system, and projection displaysystem |
| US7193671B2 (en) | 2003-09-02 | 2007-03-20 | Sony Corporation | Reflective liquid crystal display device having obliquely evaporated alignment film on vertically evaporated film, method of manufacturing the same, and vertically aligned liquid crystal display unit |
| JP3752691B2 (en) | 2003-09-11 | 2006-03-08 | ソニー株式会社 | Reflective liquid crystal display element, manufacturing method thereof, and liquid crystal display device |
| US8462299B2 (en) * | 2004-03-05 | 2013-06-11 | Sony Corporation | Reflection type liquid crystal display device, display apparatus, and projection system |
| JP2007033588A (en) * | 2005-07-25 | 2007-02-08 | Sony Corp | Liquid crystal display element and liquid crystal projector |
| JP2011227455A (en) | 2010-04-02 | 2011-11-10 | Seiko Epson Corp | Liquid crystal device and electronic equipment |
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