Optical Filter for Display Unit Color Purity
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Solution Overview
Problem
Display units using RGB primary colors face challenges in maintaining color reproduction range and viewing angle characteristics due to light leakage and alignment issues, particularly with larger substrates and finer pixels, which affect image quality.
Innovation Solution
A display unit incorporating an optical filter with a first filter layer that transmits a central wavelength band and removes a secondary band, and a second filter layer that reduces transmissivity of a third band, enhancing color purity and correcting viewing angle fluctuations by adjusting refractive index layers to maintain chromaticity and color reproduction range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the concentration of pigment or dye in the color filter is increased to expand the color reproduction range, then the color reproduction range is improved, but the transmissivity is lowered
Solution Approach 1:
The patent introduces an interference filter as an intermediary component between the light-emitting section and the color filter. This interference filter selectively transmits specific wavelength bands while blocking others, thereby enhancing color purity without requiring increased pigment concentration in the color filter, thus maintaining transmissivity while expanding color reproduction range
2Object-affected harmful factors
If the distance between the light-emitting section and the color filter is decreased to reduce light leakage, then color mixing is reduced, but alignment accuracy becomes more difficult to maintain
Solution Approach 1:
The interference filter serves as a mediator that enables effective wavelength selection even when the distance between the light-emitting section and color filter is increased. This allows for relaxed alignment requirements while still achieving low light leakage and reduced color mixing through the interference filter's wavelength-selective properties
Solution Approach 2:
The patent replaces the mechanical alignment system (which relies on precise positioning between light-emitting section and color filter) with an optical interference system. The interference filter's wavelength-selective properties are achieved through optical path differences rather than mechanical precision, thereby reducing the impact of alignment variations
3Manufacturing precision
If the opening of the light-emitting section is narrowed to improve alignment margin, then alignment accuracy is improved, but the current density increases and luminance deteriorates
Solution Approach 1:
The interference filter acts as an intermediary that enables effective color filtering without requiring a narrowed light-emitting section opening. By using wavelength-selective interference rather than geometric alignment, the system maintains larger openings that preserve current density and luminance while still achieving low light leakage
4Quantity of substance
If an interference notch filter is combined with a color filter to enhance color purity, then the color reproduction range is expanded, but chromaticity changes easily depending on viewing angle
Solution Approach 1:
The patent segments the wavelength selection function into two parts: the interference filter handles wavelength-selective blocking of unwanted bands, while the color filter handles the primary color transmission. This segmentation allows each component to optimize its function independently, with the color filter's broader transmission characteristics compensating for viewing-angle-induced chromaticity shifts
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 solution effectively expands the color reproduction range while improving viewing angle characteristics by selectively removing unwanted wavelength bands and offsetting chromaticity changes, thus enhancing image quality without requiring precise alignment of light-emitting sections.
Implementation Method 1
an optical filter that transmits color light beams while selectively removing a part of a wavelength band of the color light beams
Data Source
AI summary
A display unit includes a plurality of light-emitting sections and an optical filter. The plurality of light-emitting sections emit color light beams having different colors. The optical filter is disposed on light emission side of the plurality of light-emitting sections, and transmits the color light beams while selectively removing a part of a wavelength band of the color light beams. The optical filter includes the first filter layer and the second filter layer. The first filter layer transmits a first band including a center wavelength out of the wavelength band of each of the color light beams, and removes a second band that is at least a part of a band other than the first band. The second filter layer reduces transmissivity of a third band that is a part of the first band of at least one color light beam out of the color light beams.