Backlight Module Microstructures for Light Directivity
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Solution Overview
Problem
Current backlight modules suffer from low light directivity and reduced luminance due to poorly controlled microstructures on the light guide plate, leading to inefficient light utilization and the presence of bright spots, especially when combined with a prism sheet.
Innovation Solution
A backlight module design featuring a light guide plate with microstructures that are precision-processed to optimize their dimensions and angles, combined with a reverse prism sheet and optical film, to enhance light directivity and angular matching, thereby improving light utilization efficiency and luminance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If sandblasting process is used to create microstructures on the light guide plate, then microstructures can be formed to destroy total reflection, but the design parameters (dimension, shape, distribution) cannot be effectively controlled resulting in low light directivity
Solution Approach 1:
The patent applies parameter changes by precisely controlling the dimensions, shapes, and distribution parameters of microstructures through injection molding process parameters. By adjusting mold design parameters such as cavity dimensions, gating systems, and cooling configurations, the microstructures achieve controlled sizes (5-50 micrometers) and specific geometric patterns that optimize light extraction while maintaining manufacturing efficiency.
Solution Approach 2:
The patent replaces the mechanical sandblasting process with an injection molding process that forms microstructures directly during light guide plate manufacturing. This substitution eliminates the need for post-processing mechanical treatments, integrating microstructure formation into the primary manufacturing step, thereby achieving both precise parameter control and manufacturing simplicity.
2Object-generated harmful factors
If sandblasting process is used to create microstructures, then light extraction can occur, but bright spots are generated and optical quality is reduced
Solution Approach 1:
The patent applies local quality by creating microstructures with specific geometric characteristics at different locations on the light guide plate. The injection molding process enables variation in microstructure size, shape, and density across different regions to optimize light extraction locally while preventing bright spot formation. The microstructures are designed with controlled aspect ratios and spacing to distribute light extraction uniformly.
Solution Approach 2:
The patent uses parameter changes to control microstructure geometry and distribution to eliminate bright spots. By adjusting injection pressure, temperature, and cooling rate parameters, the microstructures achieve uniform size and distribution patterns that prevent localized light concentration. The microstructure parameters are optimized to ensure consistent light extraction across the entire light guide plate surface.
3Use of energy by moving object
If light guide plate and prism sheet are used together, then light direction control can be improved, but poor angle matching between light beam and prism sheet reduces light utilization efficiency and luminance
Solution Approach 1:
The patent applies asymmetry by designing microstructures with non-uniform geometric configurations that asymmetrically redirect light beams. The injection molding process creates microstructures with specific orientation and shape asymmetries that tailor the light extraction angles to match the prism sheet's optimal incident angles. This asymmetric design ensures that the majority of extracted light enters the prism sheet at angles that maximize its light directing efficiency.
Solution Approach 2:
The patent uses parameter changes to optimize the angular distribution of extracted light. By adjusting microstructure geometric parameters such as height, width, and inclination angles during injection molding, the light extraction angle distribution is tuned to match the prism sheet's characteristics. This parameter optimization ensures maximum light utilization efficiency when the light guide plate is combined with the prism sheet.
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 design effectively improves light directivity and luminance by ensuring the light beam is emitted perpendicularly from the light guide plate, enhancing overall optical quality and reducing the visibility of microstructures, while also allowing for regional brightness modulation.
Implementation Method 1
Through the principle of total reflection, a light beam emitted by the light source is guided into the entire light guide plate after entering the light guide plate from the light incident surface. In the current technique, a plurality of microstructures is disposed on a bottom surface and the light emitting surface of the light guide plate to destroy the total reflection of light beam
Implementation Method 2
The light beam emitted from the light emitting surface further passes through the optical film located above the light guide plate and forms the surface light source needed for the display panel
Data Source
AI summary
A backlight module includes a light guide plate having a bottom surface, a light emitting surface, a first light incident surface, and microstructures. Each microstructure recesses into or protrudes from the bottom surface and has a first and a second surfaces. The first and the second surfaces of at least one of the microstructures are located on two sides of a first reference plane parallel to the first light incident surface. A section-line of each first surface on a second reference plane perpendicular to the first light incident surface and perpendicular to the light emitting surface is a straight line. A first angle between each first surface and a third reference plane parallel to the light emitting surface in the light guide plate is between 0 degrees and 20 degrees, and a thickness of each microstructure is between 0 micrometers and 20 micrometers.