1. Light Control Film for Cholesteric LCD Image Quality Enhancement
Speaker: Ching-Yao Huang (黃靖堯)
Advisors: Prof.Yi-Pai Huang (黃乙白教授)
Prof.Chung-Hao Tien (田仲豪教授)
Institute of Electro-Optical Engineering,
National Chiao Tung University, Hsinchu, Taiwan
Oct

2. Outline Introduction Motivation and objective Simulation module
Conclusions and future works

3. Introduction of Cholesteric LCD
E-book
Billboard
Advantages:
Low power consumption
Stable structure
No color filter
Disadvantages:
Specular reflection
The glare effect
Color shift

4. Outline Introduction Motivation and objective Simulation module
Conclusions and future works

5. Motivation Line light source X LCF Viewing region
Substrate
Electrode
Alignment layer
LCF
Cholesteric LC
Ch-LCD
Viewing region
Alignment layer
Electrode
Substrate
The lens specification can be determined by the position of light source, display, and viewers.

6. The position of light source and display size
Objective
Measurement
(BRDF of the display)
Indoor large billboard
Ch-LCD
The position of light source and display size
Optical film
Mathematical module
Film design
Light source
The viewing region
Uniform illumination

7. Outline Introduction Motivation and objective Simulation module
Conclusions and future works

8. BRDF Bidirectional reflectance distribution function(BRDF) Definition:
BRDF defines the reflective characteristic of the surface.

9. Simulation Structure 10cm 20cm 30cm 14.03 ° 5.71 ° 180cm 160cm 20mm
LCF
Up glass
Ch-LC cell
Low glass
Light source
Light source
20cm
10cm
Ch-LCD
30cm
14.03 °
10mm
20mm
5.71 °
180cm
160cm 2m
15mm

10. Microstructure ρ=25° ρ=50° ρ: incident angle σ: reflection angle
α, β: inclined angle of slope
ρ=60°
The mark area is the slope range of micro-lens
corresponding to the expected reflection angle.

11. Simulation result
The reflected light redistributed to the expected region by adding the LCF in front of the display.
Bare Ch-LCD
With LCF

12. Outline Introduction Motivation and objective Simulation module
Conclusions and future works

13. Conclusions
The design process can get the appropriate parameters of the micro-lens.
The angular distribution of reflected light with LCF redistributed to the expected value in simulation.
The incident angle can’t be too large that causes the shadow effect.

14. Future Works Realize the design of LCF .
Verify the design process with the experimental result and improve if there is any drawback.
(1) BRDF
(2) Experimental setup

15. Thanks for your kind attention

16. The curved surface can be expressed as:
Its tangent vector is:
The wavefront unit vector of incident light

17. Light source

18. Conic constant k = 0 sphere -1 < k < 0
ellipse with major axis on the z axis
k = -1
parabola
k < -1
hyperbola
k > 0
oblate sphere (ellipse swept about minor axis)

19. Planar texture
Focal conic texture
Homeotropic texture