Prism Sheet Refractive Index Optimization for LCD Luminance
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Solution Overview
Problem
Existing illumination apparatuses for liquid crystal displays do not effectively optimize front luminance and light extracting efficiency due to neglecting the refractive index in the thickness direction of the prism sheet, despite optimizing the combination of the polarization plate and in-plane refraction axes in the ridge line and arrangement directions.
Innovation Solution
The illumination apparatus incorporates a light transmission film with prisms having refractive indices in the ridge line, arrangement, and thickness directions optimized such that one axis with a larger refractive index is perpendicular or parallel to the transmission axis of the polarization plate, improving the combination of the polarization plate and refraction axes in all three directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the refractive index in the thickness direction of the prism sheet is not optimized, then the device complexity is reduced, but the front luminance and light extracting efficiency deteriorate
Solution Approach 1:
The patent applies parameter changes by optimizing the refractive index in the thickness direction (nz) of the prism sheet relative to the refractive indexes in the ridge line (nx) and arrangement (ny) directions. Specifically, it establishes that nx > ny and nz > ny, creating a specific refractive index relationship that enhances front luminance and light extracting efficiency without adding device complexity
Solution Approach 2:
The patent transitions from optimizing only in-plane refraction axes (ridge line and arrangement directions) to including the thickness direction refraction axis. This dimensional expansion from 2D to 3D optimization enables comprehensive control of light propagation, improving both front luminance and light extracting efficiency
2Productivity
If the refractive index in the thickness direction is not considered, then the manufacturing process is simplified, but the light extracting efficiency deteriorates
Solution Approach 1:
The patent changes the refractive index parameter in the thickness direction (nz) to be greater than the refractive index in the arrangement direction (ny), while maintaining nx > ny. This specific parameter configuration optimizes light extraction efficiency by controlling total internal reflection at the prism interfaces, achieving high productivity without complicating the manufacturing process
3Illumination intensity
If the refractive index relationship is not optimized, then the device structure is simpler, but the luminance distribution and view angle characteristics deteriorate
Solution Approach 1:
The patent optimizes luminance distribution and view angle characteristics by establishing specific refractive index relationships: nx > ny and nz > ny. This parameter configuration controls the angular distribution of extracted light, ensuring uniform luminance across different viewing angles while maintaining a simple device structure without additional optical elements
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 optimization enhances front luminance and light extracting efficiency, leading to improved luminance and reduced power consumption in liquid crystal display apparatuses, with different configurations suited for various applications based on specific refractive index relationships.
Implementation Method 1
the light transmission film is disposed such that one axis along a direction in which the prism has a larger refractive index, of two axes along a ridge line direction and an arrangement direction, is perpendicular to a transmission axis of the polarization plate
Implementation Method 2
The illumination apparatus includes a polarization plate, a light source, and a light transmission film
Data Source
AI summary
An illumination apparatus is disclosed. The illumination apparatus includes a polarization plate, a light source, and a light transmission film disposed between the polarization plate and the light source and including a plurality of prisms formed on a surface thereof. The plurality of prisms each have a ridge line in a first direction and are continuously arranged in a second direction perpendicular to the first direction. The light transmission film is disposed such that a ridge line direction of the plurality of prisms is one of a perpendicular direction and an approximately perpendicular direction to a transmission axis of the polarization plate. The plurality of prisms each have refractive indexes in the ridge line direction, an arrangement direction, and a thickness direction, the refractive index in the ridge line direction being larger than the refractive indexes in the arrangement direction and thickness direction.