2001 Fiscal Year Final Research Report Summary
Brightness Enhancement of Fluorescent Liquid Crystal Display
| Project/Area Number |
12650335
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
電子デバイス・機器工学
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| Research Institution | AKITA UNIVERSITY |
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Principal Investigator |
YAMAGUSHI Rumiko Akita University, Faculty of Engineering and Resource Science, Research Associate, 工学資源学部, 助手 (30170799)
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| Project Period (FY) |
2000 – 2001
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| Keywords | Nematic Liquid Crystal / Guest-Host Effect / fluorescent dve / dichroic ratio / Liquid Crystal Display |
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| Research Abstract |
Emissive LCDs in which a dichroic phosphor is dissolved as a guest material have been reported and a multicolor display has been demonstrated by combining functions of the UV shutter and of the emitter in the fluorescent LC cell. Moreover, a brightness was enhanced by the use of the polarization property of the fluorescence emitting from the LC cell.
(1) 14 fluorescent dyes and 9 nematic liquid crystals were prepared, and absorption and emission spectra were measured in their combinations (14×9), In this study, a dichroic phosphor was firstly dissolved in a liquid crystal with negative dielectric anisotropy (n-type) and the dichroic ratio was investigated.
(2) The fluorescent homogeneous LC cell, fluorescent 90℃ twisted nematic (TN) LC cell and the polarizer were stacked. When the voltage was applied to the TN cell, the fluorescent color can be switched from homogeneous cell to TN cell. The brightness increases more than two times due to using the conventional polarizer for the visible light, compared to the former fluorescent LCD mode. Moreover, a novel fluorescent LCD mode in which n-type homeotropic GH LC layer and p-type (positive dielectric anisotropy) homogeneous GH LC layer are stacked was proposed. The fluorescent color switching is successfully demonstrated and the brightness was about 1.5 times higher than that of the former display mode using only p-type fluorescent LCs.
(3) Light-emitting type LCDs in which LED and EL devices were used as a back light and a excitation lightsource. Dichroic phosphors were dissolved in a nematic LC and the guest-host type LC cells are made. The emission color change from fluorescence to the back light was successfully demonstrated.
(4) A novel LCD consisting of the emissive reflector and the TN LC layer containing a dichroic fluorescent dye was proposed. In the emission mode, the fluorescent color was changed from the LC one to the reflector's. In the reflection mode, the "black on colored light" type display can demonstrated.
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Research Products
(8 results)
