Photoluminescent Sheet with Rough Passivation Film
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Solution Overview
Problem
Photoluminescent sheets used in liquid crystal display back light units face issues with moisture accumulation and contact-related deterioration when connected to other sheets, leading to a 'wet' appearance on the screen.
Innovation Solution
A photoluminescent sheet design incorporating a phosphor for light absorption and emission, a matrix for light penetration, and a passivation film with a rough surface to minimize contact area with adjacent sheets, potentially including beads for further reduction of contact points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the photoluminescent sheet is connected to other sheets with a smooth surface, then light diffusion and color conversion are improved, but moisture accumulation and contact-related deterioration occur leading to wet appearance on screen
Solution Approach 1:
The passivation film is applied selectively to specific regions of the photoluminescent sheet where moisture accumulation is most problematic, rather than covering the entire surface. This allows light diffusion areas to remain smooth while contact-prone areas gain moisture protection through the passivation film coating
Solution Approach 2:
The solution combines the photoluminescent material (for light conversion) with a passivation film (for moisture protection) to create a composite structure. The passivation film is applied over the photoluminescent sheet, forming a protective layer that prevents moisture ingress while allowing the underlying photoluminescent properties to function
2Reliability
If a passivation film is added to prevent moisture accumulation, then reliability is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
A thin passivation film is applied to the photoluminescent sheet to provide moisture protection. The film is sufficiently thin that it does not significantly alter the optical properties or add substantial complexity to the overall device structure, while still providing effective barrier protection against moisture
Solution Approach 2:
The passivation function is merged with the existing photoluminescent sheet structure rather than being implemented as a separate, complex subsystem. The passivation film is integrated into the sheet assembly process, combining protective functionality with the existing structural framework
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 prevents moisture-related issues and ensures proper contact between sheets, maintaining the display's integrity and performance by reducing the contact area and enhancing light diffusion and color conversion functions.
Implementation Method 1
a phosphor, for absorbing some light, of at least one wavelength, of light emitted from a light source and emitting particular light of a wavelength different from the wavelength of the emitted light
Implementation Method 2
a roughness is formed on a surface of the passivation film to reduce a contacting area between the photoluminescent sheet and another sheet
Data Source
AI summary
A photoluminescent sheet is disclosed. In one embodiment, the photoluminescent sheet includes i) a phosphor, for absorbing some light, of at least one wavelength, of light emitted from a light source and emitting particular light of a wavelength different from the wavelength of the emitted light, ii) a matrix, for having the phosphor, the remaining of the light emitted from the light source penetrating the matrix and iii) a passivation film, for being laminated to at least one surface of the matrix, whereas a roughness is formed on a surface of the passivation film to reduce a contacting area between the photoluminescent sheet and another sheet. According to one embodiment of the present invention, wet is not generated on a screen even though the photoluminescent sheet is connected to other sheets.