Backlight Light Guide Plate Refracting Portion Brightness Uniformity
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Solution Overview
Problem
Planar illumination devices for liquid crystal display devices suffer from brightness unevenness due to localized dark and bright regions near the light entering end face, caused by uneven light distribution and leakage, which affects the overall emission light quality.
Innovation Solution
The illumination device incorporates a light guide plate with a light refracting portion where the occupancy rate of unit light refracting portions is lower at the end side portions compared to the central side portion, and the length of the end side portions is optimized within specific ranges to control light diffusion and leakage, combined with a prism sheet configuration to enhance light usage efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the angle range of incident light is narrowed to improve front brightness, then the front brightness of emission light is improved, but brightness unevenness occurs with dark portions near the opposite end face and bright portions near the light entering end face
Solution Approach 1:
The patent applies local quality by differentiating the occupancy rate of unit light refracting portions between the end side portion and central side portion of the light entering end face. Specifically, the occupancy rate in the end side portion is set lower than in the central side portion, creating localized optical properties that compensate for light distribution unevenness while maintaining overall brightness uniformity across the emission plate face.
2Loss of energy
If the occupancy rate of unit light refracting portions is increased to improve light distribution, then light leakage is reduced, but brightness unevenness worsens due to excessive light concentration in the central region
Solution Approach 1:
The patent implements local quality by setting different occupancy rates for unit light refracting portions in different regions of the light entering end face. The end side portion has a lower occupancy rate to prevent excessive light concentration and reduce brightness unevenness, while the central side portion maintains a higher occupancy rate to effectively control light leakage.
Solution Approach 2:
The patent applies parameter changes by optimizing the occupancy rate within specific numerical ranges: the end side portion occupancy rate is set within 40-60% and the central side portion occupancy rate within 70-85%. These parameter adjustments balance light leakage control with brightness uniformity, resolving the contradiction between reducing light loss and maintaining uniform illumination.
3Loss of energy
If the light refracting portion covers the entire light entering end face to maximize light control, then light leakage is minimized, but brightness unevenness increases due to over-concentration of light in the central area
Solution Approach 1:
The patent applies segmentation by dividing the light entering end face into distinct regions: an end side portion and a central side portion. Each region is equipped with unit light refracting portions at different occupancy rates, allowing independent optimization of light control in each zone. This segmentation enables the system to control light leakage effectively while preventing brightness unevenness through regional differentiation.
Solution Approach 2:
The patent implements local quality by assigning different optical properties (occupancy rates) to different regions of the light entering end face. The end side portion has a lower occupancy rate (40-60%) to reduce light concentration, while the central side portion has a higher occupancy rate (70-85%) for better light leakage control, achieving both goals simultaneously.
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 suppresses brightness unevenness by reducing light leakage and ensuring uniform light distribution, improving the front brightness and display quality of the liquid crystal display device.
Implementation Method 1
a light refracting portion configured with a plurality of unit light refracting portions arranged side by side on the light entering end face along an alignment direction of the plurality of light sources, the light refracting portion being configured to refract incident light
Data Source
AI summary
A backlight device includes at least a plurality of LEDs arranged in a row, a light guide plate including at least a light entering end face having a plate shape, and a light refracting portion configured with a plurality of unit light refracting portions arranged side by side on the light entering end face along an alignment direction of the plurality of LEDs, wherein in the light refracting portion, an occupancy rate occupied by the unit light refracting portion in an end side portion of the light entering end face in the alignment direction is made lower than an occupancy rate occupied by the unit light refracting portion in a central side portion of the light entering end face in the alignment direction.