LCD Backlight Segments with Stacked Reflection Walls
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Solution Overview
Problem
Existing liquid crystal display devices face challenges in achieving high contrast and uniform luminance distribution due to light leakage between segments in local dimming, especially when using multiple LEDs or a diffusion sheet, which compromises the effectiveness of local dimming.
Innovation Solution
A liquid crystal display device with a back light configuration that includes a stacked structure of lower and upper reflection walls surrounding each segment, where each segment contains at least one LED, and is covered by a transparent resin, with the walls formed from silicone resin containing reflective pigments, and an optical sheet group disposed in an empty space surrounded by these walls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If multiple LEDs are placed on each segment, then luminance uniformity is improved, but light leakage into neighboring segments increases
Solution Approach 1:
A transparent resin is introduced as an intermediary medium between multiple LEDs within the same segment. This resin allows light from multiple LEDs to be effectively combined and distributed uniformly across the segment while preventing light from leaking into neighboring segments, thus resolving the contradiction between luminance uniformity and light leakage control.
Solution Approach 2:
The patent applies different optical properties to different regions: the transparent resin is specifically positioned within segment boundaries to provide localized light diffusion and uniformity enhancement, while reflection walls are positioned at segment boundaries to provide localized light confinement. This localized application of different optical functions resolves the contradiction between needing multiple LEDs for uniformity and preventing their light from leaking.
2Illumination intensity
If a diffusion sheet is placed to improve luminance uniformity, then light distribution is improved, but light leakage into neighboring segments increases
Solution Approach 1:
The transparent resin serves as an intermediary that performs the light-diffusing function traditionally performed by diffusion sheets, but with the added benefit of being confined within segment boundaries. This allows uniform light distribution within each segment while preventing the diffusion effect from causing light to leak into neighboring segments.
Solution Approach 2:
The patent uses a thin transparent resin layer as a flexible optical element that can be precisely positioned within segment boundaries. Unlike traditional diffusion sheets that are applied over the entire display area, this resin is confined to specific segments, providing localized diffusion without causing light leakage between segments.
3Illumination intensity
If segment area is reduced for better local dimming control, then contrast is improved, but it becomes difficult to place multiple LEDs on each segment
Solution Approach 1:
The patent changes the optical parameters of the resin material to achieve superior light diffusion and confinement properties. By selecting resin with specific refractive index and optical scattering characteristics, the system can maintain effective local dimming control with smaller segments while still accommodating multiple LEDs through enhanced light distribution within the confined space.
4Ease of manufacture
If only one LED is placed on each segment, then manufacturing is simplified, but luminance uniformity deteriorates and LEDs become visible
Solution Approach 1:
The transparent resin acts as an intermediary that compensates for the limitation of using a single LED per segment. By strategically positioning the LED and utilizing the resin's light-diffusing properties, the system achieves improved luminance uniformity across the segment while maintaining the manufacturing simplicity of using only one LED, thus resolving the contradiction between ease of manufacture and luminance uniformity.
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 prevents light leakage between segments, ensuring high-contrast and high-definition images by accurately controlling light distribution, reducing manufacturing complexity and costs.
Implementation Method 1
the lower reflection wall and the upper reflection wall are formed from silicone resin which include reflective pigments
Implementation Method 2
the light emitting diode is covered by a transparent resin
Data Source
AI summary
A task of the present invention is to realize a display device with high definition and high contrast by means of local dimming. The configuration is as follows. A liquid crystal display device including a display panel and a back light, the back light having a light source and a group of optical sheets, the light source including a light source substrate and LEDs arranged on the light source substrate, the light source being divided into segments in a plan view, the segment including at least one LED, characterized in that the segment is surrounded by a stacked structure of a lower reflection wall and an upper reflection wall.