Prism Side Surfaces Light Guide Plate Brightness Uniformity
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Solution Overview
Problem
Conventional planar light source apparatuses experience uneven brightness and low light utilization efficiency due to non-uniform light diffusion and reflection at the side surfaces of the light guide plate, leading to inefficiencies in light output.
Innovation Solution
A planar light source apparatus featuring a light guide plate with a rectangular shape and second side surfaces configured as prisms with a sawtooth-like cross-section, which refract light away from the point light source, combined with a reflection sheet and optical sheet for improved light distribution and utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a hole portion is formed in a light guide plate and an LED is arranged at the center, then light incident efficiency is improved, but brightness uniformity deteriorates due to reflection at side surfaces
Solution Approach 1:
The patent applies local quality by configuring only specific side surfaces (second side surfaces) as prisms while leaving other side surfaces (first side surfaces) as flat surfaces. This localized prism configuration selectively refracts light in specific regions to improve brightness uniformity without affecting the overall light incident efficiency achieved by the central hole structure.
Solution Approach 2:
The patent introduces asymmetry by making the second side surfaces have a prism configuration with sawtooth-like cross-sections, which breaks the symmetry of the light guide plate structure. This asymmetric design causes light to be refracted at specific angles, preventing direct reflection back to the light source and improving brightness distribution uniformity.
2Illumination intensity
If light is outputted from the light guide plate and reflected at a reflecting plate, then light utilization efficiency deteriorates, but brightness uniformity may be improved
Solution Approach 1:
The patent converts the harmful effect of light reflection at side surfaces into a beneficial effect by using prism configurations. Instead of light reflecting uselessly back to the source, the prism structures refract light at specific angles to propagate away from the light source, thereby improving both brightness uniformity and light utilization efficiency simultaneously.
Solution Approach 2:
The patent changes the physical parameter of the side surfaces from flat to prism-shaped with specific angles. This parameter change alters the light interaction mode from simple reflection to controlled refraction, enabling light to be directed at optimal angles for both uniformity and efficiency.
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 configuration ensures uniform light distribution and enhanced brightness across the output surface, reducing reflection losses and improving light utilization efficiency.
Implementation Method 1
Each of the pair of second side surfaces is at least partially configured as a prism whose ridge line extends in a direction perpendicular to the output surface and whose cross-section, when sectioned in a direction parallel to the output surface, has a sawtooth-like shape in which concavity and convexity are repeated. Such a configuration enables a light incident on the light guide plate and having reached the second side surface to be refracted in a direction away from the point light source.
Data Source
AI summary
A planar light source apparatus includes a point light source and a light guide plate shaped like a flat plate with a rectangular shape in a plan view. The light guide plate includes an output surface confronting an opening portion, a pair of second side surfaces opposed to each other, and a hole opening in a non-output surface and formed near one of the first side surfaces at a position where the point light source is to be arranged. Each of the pair of second side surfaces is at least partially configured as a prism whose ridge line extends in a direction perpendicular to the output surface and whose cross-section, when sectioned in a direction parallel to the output surface, has a sawtooth-like shape in which concavity and convexity are repeated. A light of the point light source can be efficiently uniformized in the light guide plate, and thus unevenness of brightness can be prevented.