Optical Sheet with Light Diffusing Layer for Color Consistency
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Solution Overview
Problem
Conventional optical sheets used in display devices cause a change in color when viewed from different angles due to wavelength dispersion of light during refraction, affecting image quality.
Innovation Solution
An optical sheet comprising a plurality of layers, including a light diffusing material-containing layer with optical diffusing particles and a refractive index and Abbe number relationship that controls wavelength dispersion, and prisms with light-absorbing portions to manage light transmission and absorption, ensuring minimal color change with angle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional optical sheets with light-transmitting portions and triangular structures are used to disperse light at large angles, then light dispersion capability is improved, but color change depending on viewing angle occurs due to wavelength dispersion during refraction
Solution Approach 1:
The patent introduces a light diffusing material-containing layer as an intermediary between the image source and the optical functional sheet layer. This layer contains particles with specific refractive index and Abbe number relationships that mediate the light path to reduce wavelength dispersion effects. The particle layer acts as a buffer that diffuses light before it enters the prism structures, thereby maintaining color consistency while preserving light dispersion capability.
Solution Approach 2:
The patent applies parameter changes by carefully selecting materials with specific optical parameters. The light diffusing material-containing layer uses particles where the refractive index difference (NdR - NdK) and Abbe number difference (νdR - νdK) satisfy specific relationships. By controlling these physical parameters of the materials, the patent achieves reduced wavelength dispersion and minimized color change across different viewing angles while maintaining effective light dispersion.
2Use of energy by moving object
If prisms are arranged in parallel to transmit light through the optical sheet, then light transmission efficiency is improved, but wavelength dispersion during refraction causes color shift at different observation angles
Solution Approach 1:
The patent applies preliminary action by placing the light diffusing material-containing layer before the light enters the prism structures. This layer pre-diffuses the light and reduces the impact of wavelength-dependent refraction that would occur in the prisms. By performing this diffusion action in advance, the patent maintains high light transmission efficiency through the parallel prism arrangement while minimizing color shifts at different observation angles.
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 optical sheet effectively controls color change with angle, enhancing image quality by diffusing light in a way that reduces wavelength-dependent dispersion, providing a consistent color perception across different viewing angles.
Implementation Method 1
a light diffusing material-containing layer (18) with optical diffusing particles dispersed in a sheet-shaped base material
Implementation Method 2
one of the causes of a change in color depending on the angle for observing an image is wavelength dispersion of light occurred when the light is refracted
Implementation Method 3
light-absorbing portions (14, 14, . . . ) arranged in parallel between the prisms in such a way as to absorb light
Implementation Method 4
prisms (13, 13, . . . ) arranged in parallel along a surface of the optical sheet in such a way that light is transmittable
Implementation Method 5
the sheet reflects image light at an interface between the portions for transmitting image light and the triangular structure to disperse the light
Data Source
AI summary
Provided is an optical sheet hardly causing a change in color depending on the observation angle of an image, the optical sheet including a plurality of layers, at least one of the layers being an optical functional sheet layer including prisms arranged in parallel along a surface of the optical sheet such that light is transmittable; and light-absorbing portions arranged in parallel between the prisms in a way to absorb light, at least another one of the layers being a light diffusing material-containing layer with optical diffusing particles dispersed in a base material, and the optical sheet satisfying a relation of NdK <NdR and vdK <vdR, wherein NdK is a refractive index of the base material of the light diffusing material-containing layer, vdK is an Abbe number thereof, NdR is a refractive index of the optical diffusing particles and vdR is an Abbe number thereof.