Optical Film Light Absorption for Display Contrast
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Solution Overview
Problem
Conventional liquid crystal displays experience light leakage at large viewing angles due to the total reflection of light at the optical lens structure, leading to reduced contrast ratios when the incident angle exceeds a critical value.
Innovation Solution
An optical film with a light-guiding layer and light absorption members is used, where the light-guiding members are disposed in recessed portions of the light-guiding layer, and the light absorption members cover the side surfaces of the light-guiding members, with refractive indices optimized to prevent total reflection and enhance light divergence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If an optical lens structure with lower refractive index is used to increase light emitting angle, then light divergence is improved, but total reflection occurs at side edges leading to reduced contrast ratio
Solution Approach 1:
A light absorption layer is introduced as an intermediary between the optical lens structure and the surrounding medium. This absorption layer has a refractive index between that of the optical lens structure and the surrounding medium, preventing total internal reflection at the side edges of the lens while maintaining the light divergence function. The absorption layer absorbs light that would otherwise be totally reflected, thereby improving contrast ratio without sacrificing viewing angle performance.
Solution Approach 2:
The refractive index parameter of the light absorption layer is specifically optimized to be between the refractive index of the optical lens structure and the surrounding medium. This parameter selection prevents the occurrence of total internal reflection by ensuring gradual refractive index transition, thereby eliminating light leakage at large viewing angles while preserving the light-emitting angle enhancement provided by the optical lens structure.
2Adaptability or versatility
If light is incident into the optical lens at large incident angle, then light divergence function is achieved, but light is totally reflected off the side surface reducing front view contrast
Solution Approach 1:
The light absorption layer serves as a mediator between the optical lens structure and the external environment. When light enters the optical lens at large incident angles, the absorption layer prevents total internal reflection at the side surfaces by providing a gradual refractive index transition. This eliminates the harmful reflected light that would otherwise reduce front view contrast, while allowing the optical lens to maintain its light divergence function across a wide viewing angle range.
Solution Approach 2:
The invention converts the potentially harmful total internal reflection phenomenon into a beneficial effect. By introducing the light absorption layer with intermediate refractive index, the light that would have been totally reflected and caused contrast reduction is instead absorbed or gradually transmitted, transforming a harmful optical effect into a mechanism that enhances display performance across wide viewing 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 film effectively reduces the probability of light being totally reflected, thereby improving the contrast ratio, especially in the front view direction, by absorbing light that would otherwise be refracted towards the viewer, resulting in enhanced display performance.
Implementation Method 1
the at least one light absorption member is disposed between the side surface of the at least one light-guiding member and the light-guiding layer, and the light absorption member covers the side surface
Implementation Method 2
The optical lens structure has a refractive index lower than that of the optical film layer such that the light emitting angle of incident light can be increased, thereby diverging incident light beams
Data Source
AI summary
The present invention provides an optical film. The optical film includes a first light-guiding layer, a second light-guiding layer, and at least one light absorption member. The first light-guiding layer has a first light incident surface, a first light-emitting surface, and an accommodating recessed portion formed on the first light incident surface. The second light-guiding layer is disposed on the first light incident surface, and has a second light incident surface, a second light-emitting surface, and a light-guiding member formed on the second light-emitting surface. Each light-guiding member is disposed on each accommodating recessed portion respectively, and each light-guiding member has a top portion, a bottom portion, and a side surface connecting the top portion and the bottom portion. The side surface of the light-guiding member faces the inner wall surface of the accommodating recessed portion, and the bottom portion of the light-guiding member corresponds to the opening of the accommodating recessed portion. The light absorption member covers the side surface. The first light-guiding layer has a first refractive index, and the second light-guiding layer has a second refractive index less than the first refractive index.