Optical Dome Geometry for LED Backlight Local Dimming
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Solution Overview
Problem
Display apparatuses face challenges in maintaining optical profiles and contrast ratios due to the expansion of optical diffusion areas, which reduces the number of blocks for local dimming and constrains the enhancement of contrast ratios, especially when using light-transmitting resin layers or lenses.
Innovation Solution
A display apparatus with a bat-wing shaped optical profile and an optical dome that maintains this profile by defining specific distances (1.70<r1/r0<1.83) for light emission, allowing for reduced optical distance or number of light sources while using a printed circuit board, LED chip, and liquid crystal panel configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a light-transmitting resin layer or lens is used to cover the light source, then the optical diffusion area is expanded, but the number of blocks for local dimming is reduced which constrains contrast ratio enhancement
Solution Approach 1:
The patent applies parameter changes by precisely controlling the ratio r1/r0 (where r1 is the distance from light source center to optical dome surface at maximum output angle, and r0 is the vertical distance from light source center to optical dome surface) within the range 1.70-1.83. This parameter optimization maintains the bat-wing optical profile while using the optical dome, allowing expansion of optical diffusion area without significantly reducing the number of local dimming blocks
Solution Approach 2:
The patent employs spheroidality by using a dome-shaped optical structure (optical dome) instead of flat or other geometric shapes. The curved surface of the optical dome refracts and distributes light in a controlled manner, maintaining the desired optical profile and diffusion characteristics while preserving the effectiveness of local dimming blocks
2Illumination intensity
If the optical diffusion area is expanded through a lens, then light distribution is improved, but contrast ratio enhancement is constrained due to reduced number of local dimming blocks
Solution Approach 1:
The patent uses parameter changes by optimizing the r1/r0 ratio within 1.70-1.83 to control the optical profile. This precise parameter control allows the system to achieve improved light distribution through the optical dome while maintaining sufficient resolution of local dimming blocks to preserve contrast ratio performance
Solution Approach 2:
The patent introduces an intermediary element - the optical dome with specifically controlled geometry - that mediates between the light source and the display panel. This intermediary structure distributes light effectively while allowing the local dimming blocks to maintain their functionality, thus resolving the conflict between light distribution and contrast ratio
3Stability of the object's composition
If a specific shape of optical dome is defined, then optical profile is maintained, but manufacturing precision requirements increase
Solution Approach 1:
The patent specifies a parameter range (r1/r0 between 1.70-1.83) rather than a single precise value, which provides manufacturing tolerance. This approach maintains the essential bat-wing optical profile characteristics while accommodating normal variations in manufacturing processes, thus balancing optical performance with manufacturability
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 configuration enhances light uniformity and contrast ratios by maintaining the optical profile of the LED chip even when covered by an optical dome, allowing for a reduction in the number of light sources or optical distance without compromising image quality.
Implementation Method 1
an optical dome covering the LED chip... The optical dome satisfies 1.70<r1/r0<1.83 where r0 is a straight distance from a center of the light emitting layer to a center of the optical dome and r1 is a straight distance from the center of the light emitting layer to a surface of the optical dome along an emission line of the maximum output light
Data Source
AI summary
A display apparatus and light source device thereof are provided. The light source device includes an optical dome having a specifically defined shape to be able to maintain an optical profile of a light source. According to the disclosure, a display apparatus includes a printed circuit board (PCB), a light emitting diode (LED) chip mounted on the PCB and configured to emit light, an optical dome formed to enclose the LED chip by being dispensed on the LED chip, and a liquid crystal panel configured to block or pass light output from the LED chip, wherein the optical dome may be formed to satisfy 1.70<r1/r0<1.83 where r0 is a straight distance for light vertically emitted from the LED chip to reach a surface of the optical dome and r1 is a straight distance for maximum output light emitted from the LED chip to reach the surface of the optical dome.