Light Guide Prism Arrangement for Uniform Illumination
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Solution Overview
Problem
The brightness of the emission surface in illumination devices, such as backlights for liquid crystal display devices, is often uneven, leading to degraded image quality due to narrow viewing angles and insufficient light intensity near the light sources.
Innovation Solution
The illumination device incorporates a light guide with a specific arrangement of prisms on its second main surface, including first, second, and third areas with varying thickness and prism density, which helps to distribute light intensity uniformly across the emission surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a light source with narrow viewing angle is used, then light intensity is concentrated in a specific direction, but brightness uniformity on the emission surface deteriorates
Solution Approach 1:
The patent applies local quality by dividing the light guide into multiple regions (first, second, and third regions) with different optical characteristics. Each region has prisms with specific inclination angles tailored to its position, creating localized optical properties that collectively achieve uniform brightness across the entire emission surface while maintaining high light intensity concentration from the narrow viewing angle light source.
2Area of stationary object
If light travels through a light guide from the side surface, then light can be distributed across the emission surface, but brightness uniformity deteriorates near the light source area
Solution Approach 1:
The patent applies parameter changes by systematically varying the inclination angles of prisms across different regions of the light guide. The first region has prisms with a first inclination angle, the second region has prisms with a second inclination angle, and the third region has prisms with a third inclination angle. This gradual parameter change compensates for the natural brightness gradient, ensuring uniform illumination across the entire emission surface including areas near the light source.
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 arrangement ensures excellent brightness distribution and improved display quality by ensuring consistent light intensity across the emission surface, preventing brightness reduction near the light sources and enhancing overall image quality.
Implementation Method 1
The prisms are provided on the second main surface... In a sectional view, a first virtual line connecting apexes of the first prisms is inclined with respect to the first main surface
Implementation Method 2
The light from the light source enters the light guide from a side surface, travels through the light guide, and exits from an emission surface
Data Source
AI summary
In one embodiment, an illumination device includes a light guide, a light source and prisms. The light guide has a side surface and first and second main surfaces. The light source emits light to the side surface in a first emission direction. The prisms are provided on the second main surface. The second main surface has first and second areas. The prisms include first prisms in the first area and second prisms in the second area. A first virtual line connecting apexes of the first prisms is inclined with respect to the first main surface. A distance between the second area and the first main surface is greater than a distance between the first area and the first main surface.