Angular Filter for Display Light Directivity
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Solution Overview
Problem
Conventional display devices face challenges in controlling light transmittance based on incident angles, particularly for blue light, which affects light efficiency and contrast ratio.
Innovation Solution
Incorporation of an angular filter between the backlight unit and the color conversion layer, which includes a first layer with a specific refractive index and a second layer with a different refractive index, effectively blocking 50% or more of light incident at angles of 30 degrees or more, including blue light, to enhance light directivity and reduce unnecessary light emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional display devices are used without angular filter, then light transmission is maintained across all angles, but contrast ratio deteriorates due to side light leakage during pixel black states
Solution Approach 1:
The angular filter changes the optical parameters of light transmission based on incident angle. It allows light transmission at small incident angles (0-30 degrees) while blocking light at large incident angles (30 degrees or more), thereby improving contrast ratio without significantly reducing overall light transmission efficiency
Solution Approach 2:
The angular filter applies different transmission characteristics to different regions of incoming light based on their incident angles. Light rays at small angles experience high transmission while light rays at large angles experience blocking, creating spatially selective optical properties that improve contrast ratio
2Reliability
If angular filter is added to block side light, then contrast ratio is improved, but device complexity increases due to additional optical layers
Solution Approach 1:
The angular filter is constructed as a composite optical structure with multiple layers having different refractive indices. This composite design enables the filter to achieve angular-selective light blocking functionality while being integrated into the existing display device architecture, adding only one functional component rather than multiple separate elements
Solution Approach 2:
The angular filter serves multiple functions simultaneously: it blocks side light to improve contrast ratio, maintains light transmission at normal angles for display brightness, and can be integrated into existing LCD or PLD device structures. This multi-functionality reduces the need for additional separate components
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 angular filter significantly improves the contrast ratio and display characteristics by blocking side light at oblique angles, preventing light emission during pixel black states and enhancing color rendering capabilities.
Implementation Method 1
The angular filter blocks about 50% or more of a blue light incident to the angular filter at an incident angle of about 30 degrees or more
Implementation Method 2
The angular filter may include: a first layer having light transmittance and having a first refractive index; and a second layer having light transmittance and having a second refractive index different from the first refractive index
Implementation Method 3
The color conversion layer includes a phosphor, and the angular filter blocks about 50% or more of a light incident to the angular filter
Data Source
AI summary
A display device includes: a backlight unit emitting a light; a first substrate on a path of a light emitted from the backlight unit; a pixel electrode on the first substrate; a light amount control layer on the pixel electrode; a first polarizer on the light amount control layer; a color conversion layer on the first polarizer; and an angular filter between the backlight unit and the color conversion layer. The color conversion layer includes a phosphor, and the angular filter blocks 50% or more of a light incident to the angular filter at an incident angle of 30 degrees or more.