本発明においては、高分子分散型液晶層の観察側とは反対側に再帰反射層を設けたので、透明状態にある画素の照明光が正反射方向に反射して光が目に入り、黒く見えずむしろ白黒反転して著しく視認性を低下させてしまう問題が防止（緩和）できると共に、明るく、コントラストが高く、色度が高く、広視野で視認性の良い反射型高分子分散型液晶表示装置を可能にする。
In the present invention, since the retroreflective layer is provided on the side opposite to the observation side of the polymer-dispersed liquid crystal layer, the illumination light of the transparent pixel is reflected in the normal reflection direction and the light enters the eyes and becomes black. A reflective polymer-dispersed liquid crystal display that is bright, has high contrast, has high chromaticity, and has good visibility in a wide field of view, while preventing (alleviating) the problem of invisible black and white inversion and significantly reducing visibility. Enables the device.
図１に戻り、この反射型ＰＤ液晶表示装置は代表的に３つの画素Ｘ，Ｙ，Ｚからなるものとする。いま、画素Ｘ，Ｚは電圧が印加されておらず、画素Ｙには電圧が印加されているとすると、画素Ｘ，Ｚは散乱状態、画素Ｙは透明状態にあるので、適当な入射角で外光（周囲の環境光）１４がこの反射型ＰＤ液晶表示装置に入射すると、画素Ｘ，Ｚは散乱状態にあるので、後方散乱光はそのまま、前方散乱光は再帰反射層２０で一旦再帰反射されてこの反射型ＰＤ液晶表示装置の前方に位置する観察者の目に入り略白く見える。画素Ｙは透明状態であるので、外光１４は再帰反射層２０で外光１４の入射方向と反対方向にのみ再帰反射光１６として反射され、外光１４の入射方向以外の方向には反射されないので、略黒に見える（実際には、観察者が位置する前方はある程度の明るさがあるので、完全な黒にはならない。）。この場合、外光１４は正反射方向Ａへも反射されないので、従来のように透明状態にある画素Ｙからその正反射方向Ａに位置する観察者の目に反射光が入り、その画素Ｙが黒く見えず白黒反転してしまう現象は緩和される。したがって、どの方向から観察しても十分にコントラストが高く、明るく、白黒反転が緩和され、広視野で視認性の良いモノクロの反射型高分子分散型液晶表示装置が実現できる。
Returning to FIG. 1, this reflective PD liquid crystal display device is typically composed of three pixels X, Y, and Z. Assuming that no voltage is applied to the pixels X and Z and a voltage is applied to the pixel Y, the pixels X and Z are in the scattered state and the pixel Y is in the transparent state. When the external light (ambient ambient light) 14 is incident on this reflective PD liquid crystal display device, the pixels X and Z are in a scattered state, so that the backscattered light remains as it is and the forward scattered light is retroreflected by the retroreflective layer 20. Then, it looks almost white in the eyes of an observer located in front of this reflective PD liquid crystal display device. Since the pixel Y is in a transparent state, the external light 14 is reflected by the retroreflective layer 20 as the retroreflective light 16 only in the direction opposite to the incident direction of the external light 14, and is not reflected in any direction other than the incident direction of the external light 14. Therefore, it looks almost black (actually, the front where the observer is located has some brightness, so it is not completely black). In this case, since the external light 14 is not reflected even in the specular reflection direction A, the reflected light enters the eyes of the observer located in the specular reflection direction A from the pixel Y which is in the transparent state as in the conventional state, and the pixel Y is transferred. The phenomenon of black and white inversion without appearing black is alleviated. Therefore, it is possible to realize a monochrome reflective polymer-dispersed liquid crystal display device that has sufficiently high contrast, is bright, has alleviated black-and-white inversion, and has a wide field of view and good visibility regardless of the direction of observation.
図２は、本発明に基づくカラーの反射型ＰＤ液晶表示装置の概略の構成を示す図である。この場合も、画素電極、対向電極は図示を省く。この構成は、基本的に図１のＰＤ液晶１０の観察側の透明基板１１表面に、Ｒ（赤色）透過Ｒフィルター１５Ｒ、Ｇ（緑色）透過Ｇフィルター１５Ｇ、Ｂ（青色）透過Ｂフィルター１５Ｂのアレーからなるカラーフィルター１５を配置したもので、この場合も代表的に３つの画素Ｒ，Ｇ，Ｂからなるものとする。いま、画素Ｒ，Ｂは電圧が印加されておらず、画素Ｇには電圧が印加されているとすると、画素Ｒ，Ｂは散乱状態、画素Ｇは透明状態にあるので、適当な入射角で外光（周囲の環境光）１４がこのカラー反射型ＰＤ液晶表示装置に入射すると、画素Ｒ，Ｂは散乱状態にあるため、それぞれＲ透過Ｒフィルター１５Ｒ、Ｂ透過Ｂフィルター１５Ｂを透過したＲ光、Ｂ光の後方散乱光はそのまま、前方散乱光は再帰反射層２０で一旦再帰反射されてこの反射型ＰＤ液晶表示装置の前方に位置する観察者の目に入り、それぞれ赤色、青色に見える。画素Ｇは透明状態であるので、外光１４は再帰反射層２０で外光１４の入射方向と反対方向にのみ再帰反射光１６として反射され、外光１４の入射方向以外の方向には反射されないので、略黒に見える（実際には、観察者が位置する前方はある程度の明るさがあるので、完全な黒にはならない。）。
FIG. 2 is a diagram showing a schematic configuration of a color reflective PD liquid crystal display device based on the present invention. Also in this case, the pixel electrode and the counter electrode are omitted from the illustration. This configuration basically consists of R (red) transmissive R filter 15R, G (green) transmissive G filter 15G, and B (blue) transmissive B filter 15B on the surface of the transparent substrate 11 on the observation side of the PD liquid crystal 10 in FIG. A color filter 15 composed of an array is arranged, and in this case as well, it is typically composed of three pixels R, G, and B. Assuming that no voltage is applied to the pixels R and B and a voltage is applied to the pixel G, the pixels R and B are in the scattered state and the pixel G is in the transparent state. When the external light (ambient ambient light) 14 is incident on the color reflection type PD liquid crystal display device, the pixels R and B are in a scattered state, so that the R light transmitted through the R transmission R filter 15R and the B transmission B filter 15B, respectively. The backscattered light of the B light remains as it is, and the backscattered light is once retroreflected by the retroreflective layer 20 and enters the eyes of the observer located in front of the reflective PD liquid crystal display device, and appears red and blue, respectively. Since the pixel G is in a transparent state, the external light 14 is reflected by the retroreflective layer 20 as the retroreflective light 16 only in the direction opposite to the incident direction of the external light 14, and is not reflected in any direction other than the incident direction of the external light 14. Therefore, it looks almost black (actually, the front where the observer is located has some brightness, so it is not completely black).
このカラーの反射型ＰＤ液晶表示装置の場合も、外光１４は正反射方向Ａへも反射されないので、従来のように透明状態にある画素Ｇからその正反射方向Ａに位置する観察者の目に反射光が入り、その画素Ｇが黒く見えず白黒反転してしまう現象は緩和される。したがって、どの方向から観察しても十分にコントラストが高く、明るく、色度が高く、白黒反転が緩和され、広視野で視認性の良いカラーの反射型高分子分散型液晶表示装置が実現できる。
Even in the case of this color reflective PD liquid crystal display device, since the external light 14 is not reflected in the specular reflection direction A, the eyes of the observer located in the specular reflection direction A from the pixel G in the transparent state as in the conventional case. The phenomenon that the reflected light enters the space and the pixel G does not look black and is black and white inverted is alleviated. Therefore, it is possible to realize a reflective polymer-dispersed liquid crystal display device having sufficiently high contrast, brightness, high chromaticity, mitigation of black-and-white inversion, and good visibility in a wide field of view regardless of the direction of observation.
【００２０】
【発明の効果】
以上の説明から明らかなように、本発明の反射型高分子分散型液晶表示装置によると、高分子分散型液晶層の観察側とは反対側に再帰反射層を設けたので、透明状態にある画素の照明光が正反射方向に反射して光が目に入り、黒く見えずむしろ白黒反転して著しく視認性を低下させてしまう問題が防止（緩和）できると共に、明るく、コントラストが高く、色度が高く、広視野で視認性の良い反射型高分子分散型液晶表示装置を可能にする。
0020
【Effect of the invention】
As is clear from the above description, according to the reflective polymer-dispersed liquid crystal display device of the present invention, since the retroreflective layer is provided on the side opposite to the observation side of the polymer-dispersed liquid crystal layer, it is in a transparent state. It is possible to prevent (alleviate) the problem that the illumination light of the pixel is reflected in the normal reflection direction and the light enters the eyes and does not look black but rather reverses black and white and significantly reduces visibility, and is bright, has high contrast, and colors. It enables a reflective polymer-dispersed liquid crystal display device with a high degree of visibility, a wide field of view, and good visibility.