Asymmetric Prism Sheet Lighting Device Viewing Angle
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Solution Overview
Problem
Conventional lighting devices for liquid crystal display devices suffer from poor viewing angle characteristics due to inefficient light emission beyond the frontal direction, resulting in reduced luminance and display quality.
Innovation Solution
A lighting device comprising a light-guiding plate, a first prism sheet with asymmetric unit prisms, and a second prism sheet with symmetric unit prisms, where the second prism sheet's oblique sides form equal angles with its base, enhancing light recycling and emission efficiency across various angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If two upward prism sheets with large frontal base angles (66 degrees and 80 degrees) are stacked to raise light toward the frontal direction, then frontal luminance is greatly improved, but light emission in inclined directions is markedly reduced, resulting in poor viewing angle characteristics
Solution Approach 1:
The first prism sheet employs asymmetric unit prisms where one oblique side forms a larger angle with the base than the other oblique side. This asymmetric configuration differentially controls light reflection angles, allowing simultaneous optimization of frontal luminance and inclined direction light emission, thereby resolving the viewing angle problem while maintaining high frontal brightness
Solution Approach 2:
Different regions of the prism structure are assigned different functional characteristics through the asymmetric unit prisms. The first oblique side is optimized for reflecting light toward the frontal direction to enhance luminance, while the second oblique side is optimized for maintaining light emission in inclined directions, achieving local functional differentiation that resolves the contradiction
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 improves viewing angle characteristics and luminance by effectively recycling and redirecting light, resulting in a superior display quality with wider viewing angles and higher luminance.
Implementation Method 1
a first prism sheet, placed on a light exit side of the light-guiding plate, that includes a plurality of first unit prisms
Implementation Method 2
causes incident light having fallen on the sheet bottom surface to be emitted from the prism formation surface
Data Source
AI summary
First and second prism sheets have pluralities of first and second unit prisms, respectively, arranged along a first direction and extending along a second direction, each of which has a base that is parallel to the first direction and a pair of oblique sides standing from both ends, respectively, of the base, and an angle that a second LED facing oblique side, which is one of the oblique sides that faces toward the LED, forms with respect to the base in the first direction in the second unit prism is smaller than an angle that a first LED facing oblique side that faces toward the LED forms with respect to the base in the first direction in the first unit prism.