Optical Sheet Microstructures for Graphic Display Contrast
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Solution Overview
Problem
Graphic image displays that rely on backlighting and ambient lighting face challenges in achieving high image contrast and hiding power without compromising transmittance, often requiring costly diffusing particles and light-absorbing inks that increase costs and power consumption.
Innovation Solution
The use of a light-transmitting sheet with geometric microstructure units on either the viewing or backside, combined with an ink layer in an image-forming pattern, allows for enhanced image contrast and hiding power while maintaining high transmittance, by controlling light diffusion and reflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If diffusing particles are added to the optical sheet to improve hiding power, then hiding power is improved, but transmittance is reduced
Solution Approach 1:
The patent replaces the traditional approach of using diffusing particles (mechanical/additive method) with a surface microstructure approach. The optical sheet has a smooth bulk material with microstructures formed on the surface, which control light diffusion through geometric design rather than through particle scattering. This substitution eliminates the need for diffusing particles while maintaining hiding power, thereby preserving transmittance.
Solution Approach 2:
The patent changes the approach from modifying the bulk material properties (adding particles) to modifying surface geometry parameters. By controlling the size, shape, depth, and distribution of surface microstructures, the patent achieves light diffusion control without compromising the optical transparency of the base material. This parameter change allows independent optimization of hiding power and transmittance.
2Illumination intensity
If light-absorbing ink is used to improve image contrast, then image contrast is improved, but transmittance of backlight is reduced
Solution Approach 1:
The patent segments the light control function into two separate components: the surface microstructures handle light diffusion and hiding power, while the ink layer handles only the image formation and contrast. This segmentation allows the ink layer to be optimized for image contrast without needing to provide hiding power, thereby minimizing its impact on backlight transmittance. The microstructures compensate for the reduced hiding power that would result from using less ink.
Solution Approach 2:
The surface microstructures act as an intermediary between the backlight source and the ink layer. They pre-diffuse the backlight before it reaches the ink, reducing the amount of ink needed to achieve the desired contrast. This intermediary function allows the system to achieve high image contrast with minimal ink coverage, preserving backlight transmittance.
3Adaptability or versatility
If diffusing particles are added to achieve wide viewing angles, then viewing angles are improved, but transmittance is reduced
Solution Approach 1:
The patent replaces the use of diffusing particles (bulk modification) with surface microstructures (surface geometry modification) to achieve wide viewing angles. The microstructures are designed with specific geometries that redirect light over wide angles through refraction and reflection at the microstructured surface, eliminating the need for particles that would scatter light and reduce transmittance.
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 provides improved image contrast and hiding power under various lighting conditions without reducing backlight transmittance, reducing the need for diffusing particles and light-absorbing inks, thereby lowering costs and power consumption.
Implementation Method 1
optical sheet with certain levels of light diffusion are used to 'spread-out' or diffuse the incident light from the localized backlight sources
Implementation Method 2
an ink layer that partially reflects and partially transmits the light can be applied only in front of the illuminated window areas
Implementation Method 3
a light-absorbing ink is used in the image carrying layer to absorb the majority of the ambient light (and the backlight) incident upon the areas surrounding the illuminated window areas
Data Source
AI summary
In one embodiment, a graphic image display can comprise: a backlight source; a light transmitting first sheet having a viewing side and a backside, with a plurality of geometric microstructure units on the backside; and a second layer comprising a source of graphic image information. The plurality of geometric microstructure units can be selected from microlenses, polyhedral shapes, lenticular shapes, and combinations comprising at least one of the foregoing. The graphic image display can be suitable for viewing under ambient light from the viewing side alone, under backlighting alone, and in the presence of both ambient light from the viewing side and backlighting.