Light Guide Plate Prism Design for LCD Hot Spot Suppression
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Solution Overview
Problem
Existing backlight units for liquid crystal display devices face issues with hot spots and bright/dark lines due to the placement of prisms on the light guide plate, leading to non-uniform light emission and increased power consumption, as well as impaired split light-emission properties.
Innovation Solution
A light guide plate design featuring a reflection-and-propagation surface with parallel prism grooves and a flat propagation region adjacent to the incident surface, along with prism protrusions on the outgoing surface having curved upper ends, which helps in directing light efficiently without impairing the split light-emission property.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If prisms are placed in regular array on the light guide plate to direct light toward visual directions, then luminance can be improved, but hot spots and bright/dark lines occur causing non-uniform light emission
Solution Approach 1:
The patent applies local quality by making the outgoing surface flat in regions adjacent to the incident surface where LEDs are placed, rather than applying prisms uniformly across the entire surface. This localized differentiation prevents hot spots and bright/dark lines near the incident surface while maintaining light directionality in other regions through selective prism placement.
2Illumination intensity
If two prism sheets are used to converge light into visual directions for higher luminance, then luminance can be improved, but the number of component parts increases making assembly complicated
Solution Approach 1:
The patent merges the light guiding function and the light direction function into a single integrated light guide plate structure. By forming prisms directly on the outgoing surface of the light guide plate rather than using separate prism sheets, the invention reduces the number of component parts while maintaining the ability to converge light into visual directions for high luminance.
3Manufacturing precision
If scattered dots are printed on the bottom face of the light guide plate to control luminance distributions, then uniformity can be improved, but light orientation distribution spreads to wide angle making it difficult to direct light toward visual directions
Solution Approach 1:
The patent segments the light guide plate into distinct functional regions: a flat propagation region adjacent to the incident surface for uniform light distribution, and a prism-formed outgoing surface for light direction control. This spatial segmentation allows each region to perform its specialized function without interfering with the other, achieving both uniformity and directivity.
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 design effectively suppresses hot spots and bright/dark lines, enhances light use efficiency, and maintains uniform light distribution across the liquid crystal display screen, reducing power consumption and improving screen quality.
Implementation Method 1
a reflection-and-propagation surface at which the light incident from the incident surface is reflected so as to be propagated toward the outgoing surface
Implementation Method 2
a plurality of prism grooves extending parallel to the incident surface are formed in the reflection-and-propagation surface... a plurality of prism protrusions extending orthogonal to the incident surface are formed in a diffusion-and-propagation region of the outgoing surface
Data Source
AI summary
A light guide plate includes an incident surface on which light outputted from point light sources is incident and an outgoing surface for outputting light incident from the incident surface, wherein a reflection-and-propagation surface for reflecting light toward the outgoing surface is formed in a back surface opposite to the outgoing surface. The outgoing surface is made up of a propagation region adjacent to the incident surface, a diffusion-and-propagation auxiliary region adjacent to the propagation region, and a diffusion-and-propagation region adjacent to the diffusion-and-propagation auxiliary region. Hot spots and bright/dark lines in vicinities of the incident surface are controlled primarily by curved portions of prism upper ends formed in the diffusion-and-propagation region, and viewing-angle characteristics of the light guide plate are controlled primarily by linear portions of the prisms.