Enhancement of Brightness and Contrast in Fluorescent Liquid Crystal Display Using Sensitizing Effect

已经报道了其中二向色性磷光体作为客体材料溶解的发射型液晶显示器（LCD）。利用敏化效应，证明了液晶显示器的亮度和对比度都得到了提高。（1）通过添加蓝色荧光二色性染料或荧光LC作为敏化剂，可以获得LC主体中香豆素-6的绿色荧光强度的显著增加。将该敏化应用于颜色从绿色切换到蓝色的发射型LCD，改善了绿色荧光的亮度和颜色切换特性。通过添加敏化剂，还改善了由蓝色LED和红色荧光LC单元组装的LCD中蓝色到红色之间的颜色切换。这些结果表明，通过利用敏化效应，激发背光的光利用率也增加了。（2）增感效应可以提高液晶基质中二色性染料的绿色和红色荧光强度。在有和没有敏化剂的荧光液晶盒中测量了吸收和发射二色性比之间的关系。当向单元施加电压时，由平行于LC方向的偏振UV光激发的荧光强度降低，并且变得低于由垂直于LC方向的偏振UV光激发的荧光强度。此外，它是澄清，亮度和对比度都可以提高，如果敏化剂的二色性比高于发射体。（3）通过在均匀、TN和垂直取向液晶盒中混合两种或三种荧光染料，成功地展示了发射白色荧光的液晶显示器。通过施加电压，白色荧光强度改变，而颜色保持白色。通过使用TN取向改善了陡度。垂直取向液晶盒的对比度为13.3，是三种液晶盒中最高的。

Emissive liquid crystal display (LCD) in which a dichroic phosphor is dissolved as a guest material have been reported. Brightness and contrast of the LCDsare enhanced has been demonstrated by using sensitizing effect.(1)The remarkable increase of the green fluorescence intensity from the coumarin-6 in the LC host can be obtained by adding the blue fluorescent dichroic dye or the fluorescent LC as a sensitizer. Applying the sensitization to the emissive type LCD of which color is switched from green to blue, the luminance of the green fluorescence and the color switching property are improved. The color switching between blue to red in the LCD assembled with the blue LED and the red fluorescent LC cell is also improved by adding the sensitizer. These results indicate that the light utilization of the excitation back light is also increased by using the sensitizing effect.(2)The increase of the green and red fluorescence intensity of dichroic dyes in the LC host can be obtained by the sensitizing effect. Relations between absorption and emission dichroic ratios are measured in the fluorescent LC cell with and without the sensitizer. When the voltage is applied to the cell, the fluorescence intensity which is excited by the polarized UV light parallel to the LC direction decreases and becomes lower than that excited by the polarized UV light perpendicular to the LC direction. Moreover, it is clarified that both the brightness and the contrast can be enhanced, if the dichroic ratio of the sensitizer is higher than that of the emitter.(3)Liquid crystal displays emitting white fluorescence are successfully demonstrated by mixing two or three fluorescent dyes in the homogeneous, TN and homeotropic alignment LC cell. The white fluorescence intensity changes by applying the voltage while the color maintains white. The steepness is improved by using TN orientation. The contrast ratio of 13.3 in the homeotropic alignment LC cell is the highest in three types of LC cell.