Optical Element with Recessed Surface for LCD Brightness Uniformity
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Solution Overview
Problem
Backlight units in liquid crystal displays (LCDs) face challenges in achieving uniform brightness, leading to issues like mura (non-uniform illumination) due to light concentration at the center portion, which reduces the cover region and affects display quality.
Innovation Solution
An optical element comprising a lens with a surface of incidence, a recessed first optical surface, and an extending second optical surface, coupled with a cover having a light transmittance of 70% or less, is used to control light path and distribution, preventing light concentration at the center and enhancing brightness uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a conventional light guide panel is used in the backlight unit, then the structure is simple, but light concentration occurs at the center portion causing non-uniform illumination (mura)
Solution Approach 1:
The optical element is divided into multiple functional regions: a light incident region with a first refractive index for receiving light from LEDs, and a light emitting region with a second refractive index for emitting light toward the liquid crystal panel. This segmentation allows different parts of the optical element to perform different functions, preventing light concentration at the center while maintaining structural simplicity.
Solution Approach 2:
Different regions of the optical element are assigned different optical properties (refractive indices). The light incident region has a first refractive index optimized for light reception, while the light emitting region has a second refractive index optimized for light emission. This local differentiation of optical properties enables uniform light distribution without requiring complex overall structures.
2Area of stationary object
If the cover region is reduced to simplify the optical element, then manufacturing becomes easier, but the area for controlling light distribution decreases
Solution Approach 1:
The optical element merges the light guide function and the light distribution control function into a single integrated component. By combining these functions, the patent eliminates the need for separate cover regions while maintaining effective light distribution control, thereby simplifying manufacturing without reducing the functional area.
Solution Approach 2:
The optical element serves multiple functions simultaneously: it guides light from the LEDs, controls light distribution to prevent center concentration, and emits light toward the liquid crystal panel. This multi-functionality allows the optical element to replace what would traditionally require multiple separate components, maintaining a sufficient effective area while simplifying the overall structure.
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
The solution effectively reduces light concentration at the center, improving illumination uniformity and expanding the cover region, thereby enhancing the overall display quality by ensuring even light distribution across the LCD.
Implementation Method 1
a lens 121, which refracts light incident from the light emitting element 110 and controls a luminous flux
Implementation Method 2
a cover 122 arranged on the lens 121 to cover at least a part of an upper surface of the lens 121
Data Source
AI summary
An optical element includes a lens includes a surface of incidence on which light is incident from a light source, a first optical surface recessed toward the light source, and a second optical surface extending from the first optical surface, and a cover arranged on the lens to cover at least a part of the first optical surface.