S-shaped Light Guide Plate Wedge for Backlight Leakage Control
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Solution Overview
Problem
In side-light type spread illuminating apparatuses for LCD panels, the reduction of the non-light-emitting region while maintaining high light utilization efficiency and uniformity of illumination is challenging due to light leakage issues from the light guide plate's tilted surface, which affects the frame width and thickness of the backlight.
Innovation Solution
The light guide plate's tilted surface is designed with an S-shape, featuring a convex portion on the light incident surface side and a concave portion on the emitting surface side, with an inflection point positioned closer to the emitting surface, reducing light leakage by minimizing the average tilt angle in regions prone to leakage and optimizing the shape to guide light more efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the light incident wedge portion length is reduced to decrease frame width, then the frame width is reduced, but light leakage increases and uniformity of illumination deteriorates
Solution Approach 1:
The tilted surface is designed with an S-shaped curved profile instead of a straight line, creating convex and concave portions that strategically control light reflection angles. This curvature allows the light incident wedge portion to be shorter while maintaining proper light guidance and reducing leakage at critical regions.
Solution Approach 2:
Different portions of the tilted surface have different local geometries - the convex portion has one curvature characteristic while the concave portion has another. This local variation in surface properties allows optimized light control at different locations within the shortened wedge structure.
2Length of stationary object
If the angle between tilted surface and emitting surface is increased to reduce wedge portion length, then the wedge portion length is reduced, but light leakage from the tilted surface increases
Solution Approach 1:
The S-shaped curved profile of the tilted surface replaces a simple increased angle approach. The curvature allows the surface to achieve effective light redirection over a shorter distance while the convex and concave portions work together to minimize leakage by controlling the distribution of reflection angles.
Solution Approach 2:
Instead of using a constant steep angle, the invention varies the local angle parameter along the tilted surface through the S-shaped curve. The angle changes continuously, being gentler in regions where leakage would be problematic and steeper where space is constrained, thus reducing overall wedge length while controlling light leakage.
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 reduces light leakage, enhances light utilization efficiency, and maintains uniformity of illumination, allowing for a thinner and narrower frame width without compromising luminance.
Implementation Method 1
a larger part of light entering the light guide plate through the light incident surface is emitted from the tilted surface of the light incident wedge portion to the outside
Data Source
AI summary
An illumination apparatus includes a light source, and a light guide plate having an emitting surface and a light incident portion including a curved surface, and decreasing in thickness from the light source side towards the emitting surface. The curved surface has an S-shape as viewed from a side, with a convex portion on the light source side and a concave portion on the emitting surface with an inflection point in between, but closer to the emitting surface than to the source side.