Edge-Lit LCD Backlight Uniformity via Segmented LED Assemblies
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Solution Overview
Problem
Conventional liquid crystal display devices using edge type backlight units with LEDs struggle to achieve high brightness while minimizing hot spots, as the current configuration often results in alternating bright and dark portions due to inadequate light diffusion distances.
Innovation Solution
The implementation of first and second LED assemblies with different widths and distances on opposite sides of a light guide plate, ensuring that the width-to-distance ratio of each LED assembly is greater than or equal to 0.5, and the distance of the first LED assembly is less than or equal to twice the width, to prevent hot spots and achieve high brightness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a single LED package is used in the edge type backlight unit, then the device structure is simple, but the brightness is insufficient and hot spots occur
Solution Approach 1:
The backlight unit is segmented into multiple LED packages (first and second LED packages) positioned at different locations. Each LED package has its own light guide plate section, allowing independent light emission zones that collectively achieve high brightness without requiring a single complex high-power LED assembly.
Solution Approach 2:
Multiple LED packages are merged into a unified backlight system where their light outputs combine through the light guide plate. The first LED package emits light through its light guide plate section, and the second LED package emits light through its light guide plate section, merging to create uniform high brightness across the display area.
2Length of stationary object
If LED packages are positioned close to the light guide plate to reduce size, then the profile is thinner, but hot spots and light diffusion issues occur
Solution Approach 1:
Different regions of the backlight unit have different structural characteristics. The first LED package and its light guide plate section form one local configuration, while the second LED package and its light guide plate section form another. Each local region is optimized for its specific function, with the light guide plate sections having different widths to control light diffusion locally and prevent hot spots.
3Illumination intensity
If the light guide plate width is increased to improve light diffusion, then light distribution improves, but the device width increases
Solution Approach 1:
The light guide plate is segmented into multiple sections, each with optimized width for its specific function. The first light guide plate section has a width optimized for the first LED package, and the second light guide plate section has a different width optimized for the second LED package. This segmentation allows efficient light diffusion in each section without requiring the entire light guide plate to be excessively wide.
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 effectively increases the brightness of the liquid crystal display device to 400 nits or more without hot spots, reduces production costs, and allows for a narrow bezel by optimizing light diffusion and distribution.
Implementation Method 1
the light from the LED chip 29a is incident on the light entering surface, then is refracted in the light guide plate 23 and goes out upward
Implementation Method 2
a voltage applied between the electrodes induces an electric field across the liquid crystal material. Alignment of the liquid crystal molecules in the liquid crystal material changes in accordance with the intensity of the induced electric field into the direction of the induced electric field, thereby changing the light transmissivity
Data Source
AI summary
A liquid crystal display device includes a liquid crystal panel including a display region and first to fourth non-display regions surrounding the display region; a light guide plate below the liquid crystal panel; and first and second LED assemblies facing opposite sides of the light guide plate and corresponding to the first and second non-display regions, respectively, that have different first and second widths, respectively, wherein the first LED assembly includes a plurality of first LED packages arranged at a first distance, and the second LED assembly includes a plurality of second LED packages arranged at a second distance.