Backlight Optical Filter for Luminance Uniformity
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Solution Overview
Problem
Display devices, particularly LCDs, suffer from variations in color impressions across different regions due to backlight unit characteristics, leading to degraded display performance and luminance issues.
Innovation Solution
A backlight unit with an optical filter system that allows specific wavelengths of light to pass through while reflecting others, using multiple filter elements with polymer layers of different refractive indices to reduce color impression variations and improve luminance uniformity, is integrated between a diffusion layer and a color conversion layer or applied to the light guide plate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a light-absorbing optical filter is used to remove different color impressions, then color uniformity is improved, but luminance is reduced
Solution Approach 1:
The patent converts the harmful effect of light absorption (which causes luminance loss) into a beneficial effect by using the absorbed light to excite phosphors that emit useful wavelengths. The optical filter absorbs specific wavelengths that would otherwise cause color non-uniformity, and this absorbed energy is then converted into beneficial light emission through phosphor conversion, simultaneously improving color uniformity while maintaining luminance.
Solution Approach 2:
The patent employs a composite optical filter structure combining multiple materials with different optical properties. This includes integrating phosphor materials with the optical filter substrate, creating a composite system where the filter layer absorbs harmful wavelengths while the phosphor layer converts this energy into useful light, achieving both color uniformity and luminance preservation through material composition.
2Device complexity
If the backlight unit structure is simplified, then manufacturing cost is reduced, but color impression variations increase
Solution Approach 1:
The patent makes the optical filter serve multiple functions simultaneously: it acts as a wavelength selective filter to remove harmful wavelengths, a phosphor conversion layer to generate useful wavelengths, and a light diffusion element to ensure uniform distribution. This multi-functionality allows a single integrated component to address color uniformity issues without requiring additional separate structures, thereby reducing overall device complexity while improving color impression uniformity.
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 solution enhances display performance by minimizing color impression degradations and improving luminance uniformity, thereby preventing or reducing the adverse effects of backlight structure and light source characteristics on display performance.
Implementation Method 1
each of the two or more filter elements comprising two or more polymer layers having different refractive indices
Implementation Method 2
the optical filter allowing light within a specific wavelength range to pass through while reflecting light within other wavelength ranges
Data Source
AI summary
A backlight unit includes an optical filter made of at least two or more filters. A first filter of the at least two or more filters reflects light within a first wavelength range, and a second filter of the at least two or more filters reflects light within a second wavelength range. The backlight unit has a structure that can prevent or reduce an effect on display performance, which would otherwise be caused by degradations in uniform color impression due to characteristics of light sources or a backlight structure.