Lens Sheet for Backlight Reducing Side Lobes
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Solution Overview
Problem
Conventional prism sheets used in display devices suffer from unnatural angular distribution of brightness due to side lobes, limiting the improvement of front side brightness and requiring multiple sheets for effective light collection, which complicates manufacturing and increases the risk of damage during installation.
Innovation Solution
A single lens sheet comprising a base film, a lenticular lens resin layer with cylindrical lenses, a prism resin layer with prisms, and a filling resin layer with a higher refractive index than the prism resin layer, where the refractive index of the filling resin layer is higher than the prism resin layer and the base film, allowing for stepwise light collection and reduced side lobe emission, and eliminating the need for a protection film due to the cylindrical lenses' curvature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a conventional prism sheet is used to collect light to the front surface, then the front side brightness is improved, but side lobes are generated causing unnatural angular distribution of brightness
Solution Approach 1:
The lens sheet is divided into multiple functional layers: a base film, a first lens layer with cylindrical lenses, and a second lens layer with prisms. Each layer performs a specific function in light control, with the cylindrical lenses collecting light in one direction and the prisms controlling light in the orthogonal direction, thereby eliminating side lobes while maintaining front brightness
Solution Approach 2:
Different regions of the lens sheet have different optical properties tailored to specific functions. The cylindrical lenses in the first layer have different refractive index characteristics compared to the prism structures in the second layer, allowing each region to optimize light collection and distribution for its specific purpose, preventing side lobe formation
2Illumination intensity
If multiple prism sheets are stacked to further improve front side brightness, then the brightness improvement is enhanced, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
Multiple light-collecting functions are merged into a single integrated lens sheet structure. The first lens layer with cylindrical lenses and the second lens layer with prisms are combined in one sheet, eliminating the need to stack multiple separate prism sheets. This integration maintains the light collection effectiveness while simplifying the overall device structure and manufacturing process
3Illumination intensity
If a prism sheet is used, then light collection is achieved, but the prism apex is easily damaged during manufacture and transport requiring a protection film
Solution Approach 1:
The first lens layer uses cylindrical lenses with curved surfaces instead of sharp prism apexes. The curved geometry of the cylindrical lenses eliminates the vulnerable sharp points that characterize traditional prisms, making the lens sheet inherently more resistant to damage during manufacturing, transport, and installation without requiring additional protection films
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 lens sheet enhances front side brightness while restraining side lobes, achieving a natural angular distribution of brightness with improved manufacturing efficiency and reduced risk of damage, using a single sheet instead of multiple prism sheets.
Implementation Method 1
The refractive index of the filling resin layer is higher than the refractive index of the prism resin layer, and therefore diffused light incident to the filling resin layer is refracted at the prism plane and collected to the front surface
Implementation Method 2
the refractive index of the base film is higher than the refractive index of the prism resin layer and therefore a light beam incident to the base film from the prism resin film is refracted at the surface of the base film and collected more to the front surface
Implementation Method 3
the light beam emitted from the base film is let into the lenticular lens resin layer, refracted at the convex surface of the cylindrical lens and collected to the front surface for emission
Data Source
AI summary
A lens sheet according to the invention includes a base film, a lenticular lens resin layer, a prism resin layer, and a filling resin layer. The lenticular lens resin layer includes a plurality of cylindrical lenses formed on one surface of the base film and arranged. The prism resin layer includes a plurality of prisms formed on the other surface of the base film and arranged, and has a lower refractive index than the refractive index of the base film. The filling resin layer is filled on a surface of the prism resin layer provided with the arranged prisms and has a higher refractive index than the refractive index of the prism resin layer. Therefore, the lens sheet according to the invention can restrain side lobe light emitted obliquely to the front surface.