Diffuser Plate Microlens Curvature Uniformity
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Solution Overview
Problem
Existing diffuser plates with microlens arrays suffer from luminance and color unevenness, leading to grainy image projections, and existing solutions that attempt to address these issues often result in compromised appearance quality.
Innovation Solution
A diffuser plate with a plurality of fine structures, such as microlenses, arranged on a main surface with specific pitch and standard deviation of relative luminance, and phase modulation shapes to ensure uniform diffusion properties within a desired angle range, reducing luminance and color unevenness while maintaining excellent appearance quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If microlens array is used to reduce speckle noise, then light diffusion capability is improved, but luminance and color unevenness occurs
Solution Approach 1:
The patent applies local quality by varying the curvature radius of individual microlenses based on their position within the array. Specifically, microlenses at different locations have different curvature radii, which locally adjusts the light diffusion characteristics to compensate for positional variations and reduce luminance unevenness across the screen surface.
Solution Approach 2:
The patent implements parameter changes by systematically varying the curvature radius parameter of microlenses according to their position in the array. This parameter variation is designed to control the diffusion angle and intensity of light from each microlens, thereby achieving uniform luminance distribution across the entire diffuser plate surface.
2Manufacturing precision
If parameters of microlenses are randomly distributed to reduce unevenness, then luminance uniformity is improved, but image becomes grainer
Solution Approach 1:
Instead of random distribution, the patent applies local quality by assigning specific curvature radii to microlenses based on their positional coordinates in the array. This deterministic local variation achieves luminance uniformity while maintaining image quality, avoiding the graininess that would result from random parameter distribution.
3Manufacturing precision
If two microlens arrays are used to prevent luminance unevenness, then diffusion uniformity is improved, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the microlens array into multiple regions based on positional coordinates, with each region containing microlenses of different curvature radii. This segmented approach to parameter variation achieves diffusion uniformity equivalent to using multiple arrays, but with a simpler single-array structure.
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 achieves uniform light diffusion and reduced graininess, providing a diffuser plate with improved optical properties and appearance quality by optimizing the arrangement and phase differences of microlenses.
Implementation Method 1
A diffuser plate using a microlens array is used as a screen for head-up displays and laser projectors... incident light can be appropriately diffused
Implementation Method 2
unevenness in luminance and color is likely to occur... unevenness in luminance caused by diffracted light and interference light generated by a periodic structure
Data Source
AI summary
A diffuser plate includes a plurality of fine structures having two or more types of lens functions arranged on a main surface. Intensity of diffused light within a desired diffusion angle range is substantially uniform, and the diffuser plate satisfies a relation of P×P×Sk≤400 [μm2], where P is an average pitch of the plurality of fine structures, Sk is a standard deviation of relative luminance of the plurality of fine structures in their front directions, P≤200 [μm], and Sk≥0.005. Thus, it is possible to provide a diffuser plate having a simple structure capable of achieving optical properties with little luminance and color unevenness and excellent appearance quality when an image is projected.