Transcript TN Display
LCD COMPONENTS Goals 1. Light Guiding Plates 2. Reflector Sheet 3. Light Collimator Films 4. Diffusers 5. Polarizers 6. Non - Absorptive Polarizers 7. Quarter Wave Plates 8. Compensation Films 9. Color Filters 10.Transparent Electrode Films 11.Anti-Glare and Anti-Reflection Films TN Display OFF state ON state Light Efficiency in LCDs 0.600.40 0.70 0.30 = 0.05% Light Efficiency Front Polarizer 30% 70% 40% ITO Coated Glass Color Filter (30%) Liquid Crystal Layer Active Matrix (70%) Rear Polarizer (40%) 60% 100% Light Guiding Plate (60%) Light Guiding Place (LGP) Light Guiding Plate Lamp Reflector Reflector Sheet Fluorescent Lamp Dot patterns scatter a light to change a direction of propagation Fluorescent Lamp Dot Patterns Light Guiding Place (LGP) II How to produce a homogenous plane illumination? a) Single lamp b) Double lamps Dot pattern (white ink) Dots get bigger as they are farther from the lamp Fluorescent Lamp Novel LGP HSOT Highly Scattering Optical Transmission (HSOT) Polymer II Fluorescent Lamp SiO2 Particles Reflector Sheet Novel LGP Highly Scattering Optical Transmission (HSOT) Polymer, Koike, Y., Japanese Patent Number H6-186560 (1990) by the courtesy of Koike Novel LGP Homogeneity of plane illumination Light Collimator Intensity Intensity Steer more light into narrow – viewing cone Angle Angle Light Collimator Light Collimator Brightness Enhancement Foil (BEF) Angle of Collimated Light BEF 3M Product Light Collimator Brightness Enhancement Foil II Double reflection Refraction Reflection refraction BEF Diffuser Light Guiding Plate Diffusion Improve spatial uniformity of backlight Surface diffusion type Inner diffusion type Diffusion II Improve an unevenness of backlight Diffuser LGP Polarization States Ex a) Linear Ey x x z y y b) Elliptical x x z y y c) Circular x x z y y Polarizer Stretch Axis PVA Protect Film Iodine (Forms Complex) Polarizer IV x z y Iodine Complex Transmission Axis Absorption Axis Polarizer Polarizer T T// T Non Absorptive Polarizer Brightness Enhancement Applications Brightness Enhanced 50% absorbed Recycle (a) Absorbing Polarizer (b) Reflecting Polarizer Non Absorptive Polarizer Reflecting polarizer – dual brightness enhancement film (DBEF, 3M) Stretch Axis Birefringent Polymer 1 a) b) ne1 no ne2 no Birefringent Polymer 2 a) b) ne1 no ne2 no Non Absorptive Polarizer DBEF Non Absorptive Polarizer Reflecting polarizer – cholesteric LC film (TRANSMAX, Merck NIPOCS, Nitto) Transmitted Light Quarter Wave Plate Cholesteric LC Layer Reflected Incident Light Light Incident Light Non Absorptive Polarizer Material A Material B Refractive Indices Refractive Indices of of Material A Material B Match Transmission Axis Mismatch Scattering Non Absorptive Polarizer VI Scattering polarizer Diffuse reflective polarizer film (DRPF) Stretch Axis stretches Green – positive birefringent polymer Pink – negative birefringent polymer Non Absorptive Polarizer VIII Scattering polarizer Particle dispersed polymer Stretch Axis particle Green –positive birefringent polymer Pink – isotropic particles polymer Non Absorptive Polarizer IX Scattering polarizer Stretched PDLC Stretch Axis polymer Green –LC droplets Pink – polymer Liquid crystal Quarter Wave Plate (QWP) Application – Reflective LCDs White State (EOFF) Black State (EON) Linear Polarizer Quarter Wave Plate LC Cell Reflective Electrode (Aluminum) Viewing Angle Compensation Film Wide View Film (FUJIFILM) Use discotic liquid crystal molecule for viewing angle compensation Concept Structure of the Wide View Film Compensation Film Compensation Film TN-LC Cell Alignment Layer Substrate Compensation Film Viewing Angle Compensation Film Viewing Angle Improvement with the Wide View Film 150.0 150.0 100.0 100.0 50.0 50.0 0.0 0.0 Color Filters Transmittance [%] 100 80 60 40 R G B 20 0 400 500 600 700 Wavelength [nm] Only about 1/3 of the input light can transmit Decrease the light efficiency Color Filters II Non – Absorptive CF Cholesteric CF can be recycled Light Guiding Plate Transparent Electrodes (ITO) Indium tin Oxide NOW, Zinic Oxides ? Transparent Electrode II Transmittance [%] Optical Property of ITO 100 95 SiO2: n=1.45, d=550/4n=94.8nm 90 Anti – reflection coating 85 ITO: n = 2.0 88.9% with AR without AR 80 380 480 580 680 Wavelength [nm] 780 Anti–Glare / Anti–Reflection Film Anti – Glare Film (AG Film) Surface structure of AG Film 100nm How does it work? 100nm 0nm 871nm Anti–Glare / Anti–Reflection Film II Anti–Reflection Film (AR Film) Low n Layer (Ex. SiO2: n=1.45 / d=100 nm) High n Layer (Ex. TiO2: n=2.3 / d=55 nm) (Ex. n=1.45 / d=25 nm) (Ex. n=2.3 / d=30 nm) Substrate (EX. CTA: n=1.48) Reflectance [%] 5.0 4.0 with AR without AR 3.0 2.0 1.0 0.0 380 480 580 680 Wavelength [nm] Improve the contrast ratio under ambient light 780 Summary Absorption Interference Reflection Diffraction Optics Refraction Scattering Birefrigerence Near Field & Quantum