Edge-Type Backlight Local Dimming via Electro-Optical Layer
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Solution Overview
Problem
Edge-type backlight units face challenges in precisely controlling local dimming, which affects the contrast ratio and leads to light loss in display apparatuses.
Innovation Solution
Incorporating an electro-optical layer with electrodes that change optical properties based on an electric field, allowing for precise control of light passage or scattering across the light guide plate, enabling improved local dimming capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If an edge-type backlight unit is used to achieve a thin backlight structure, then the thickness of the backlight is reduced, but the ability to precisely control local dimming deteriorates
Solution Approach 1:
The backlight unit is segmented into multiple independent light emitting regions along the edge, with each region controlled by separate light sources. This segmentation enables precise local dimming control while maintaining the thin edge-type structure, as each segment can be independently adjusted without affecting the overall thin profile of the backlight unit.
Solution Approach 2:
Different regions of the backlight unit are assigned different optical properties and control characteristics. The light guide plate incorporates position-dependent optical elements that enable varying light distribution patterns in different areas, allowing precise local dimming control in specific regions while maintaining the thin overall structure of the backlight unit.
2Illumination intensity
If local dimming is implemented in an edge-type backlight unit, then brightness control according to position is achieved, but light loss increases
Solution Approach 1:
The backlight unit incorporates feedback mechanisms that monitor the actual light output and adjust the intensity of individual light sources accordingly. This feedback control optimizes light distribution across different positions, achieving precise local dimming while minimizing overall light loss by only reducing illumination in areas where it is needed rather than uniformly dimming the entire backlight.
Solution Approach 2:
The optical parameters of the light guide plate are optimized to enhance light extraction efficiency in specific regions. By adjusting parameters such as refractive index distribution, surface microstructures, and optical element positioning, the system achieves position-dependent brightness control with minimized light loss, as the optical parameters are tailored to maximize light utilization in each local region.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enhances the contrast ratio and minimizes light loss during local dimming, providing more efficient and nuanced control over light emission in display apparatuses.
Implementation Method 1
an electro-optical layer configured to change optical properties according to an electric field
Implementation Method 2
light enters the light guide plate from the light source located on the side of the light guide plate. The light incident on the light guide plate may move from the side of the light guide plate to the center through total internal reflection inside the light guide plate
Data Source
AI summary
A display apparatus includes a light source emitting light; a light guide plate having a first surface and a second surface, and spreading light emitted from the light source therein to emit light through the first surface; and a local dimming unit configured to pass or scatter light emitted through the second surface of the light guide plate according to a position. The local dimming unit may include: an electro-optical layer configured to which optical properties change according to an electric field; and a plurality of electrodes positioned on the same plane to generate the electric field.