Micro Lens Array Border Curvature for Head-Up Display Noise Reduction
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Solution Overview
Problem
Existing headup display devices using coherent light beams suffer from interfering noise such as speckle and interference fringes, which degrade image quality and visibility, and existing noise reduction methods either require complex light source structures or result in reduced brightness.
Innovation Solution
The use of a micro lens array with micro convex lenses arranged tightly, where each lens has a diameter larger than the light beam diameter, and a curvature radius of border surfaces between lenses set smaller than the light wavelength, to diverge the light beam and prevent overlapping interfering noise, while maintaining image brightness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a laser beam with high optical energy density and directivity is used to form the image, then the image brightness and scanning efficiency are improved, but interfering noise such as speckle and interference fringes occurs due to the coherence of the laser beam
Solution Approach 1:
The patent applies local quality by making the micro lens array non-uniform: the lens pitch varies across different regions, and the curvature radius of border surfaces between lenses is specifically controlled to be smaller than the light wavelength. This local variation in optical properties allows the system to maintain laser coherence benefits while reducing interference patterns in specific critical areas.
Solution Approach 2:
The patent changes key optical parameters of the micro lens array: (1) varying the lens pitch across different regions rather than using uniform spacing, and (2) controlling the curvature radius of border surfaces to be smaller than the light wavelength. These parameter changes disrupt the regular interference patterns caused by laser coherence while preserving the overall optical functionality.
2Object-affected harmful factors
If micro convex cylindrical lenses are arranged as a micro lens array with beam diameter smaller than lens pitch, then interfering noise is removed, but the light source and scanning structure become complex
Solution Approach 1:
Instead of requiring complex pulsed light sources and scanning synchronization, the patent uses local quality variation in the micro lens array itself - non-uniform lens pitch and controlled border surface curvature - to passively eliminate interference noise while allowing continuous light beam scanning.
Solution Approach 2:
The patent changes the physical parameters of the micro lens array (lens pitch distribution and border surface curvature radius) to achieve noise reduction, replacing the need for complex temporal modulation of the light source with spatial parameter optimization of the optical element.
3Object-affected harmful factors
If an optical shield layer is provided on border portions to block light beam, then interfering noise is removed, but the brightness of the displayed enlarged virtual image decreases
Solution Approach 1:
The patent applies local quality by creating optical asymmetry at border regions through controlled curvature radius smaller than the wavelength, which selectively suppresses interference patterns at lens boundaries while allowing the main light beam to pass through the micro lenses undisturbed, thus eliminating noise without reducing overall image brightness.
Solution Approach 2:
The patent uses curvature control of the border surfaces between lenses, making the curvature radius smaller than the light wavelength. This curved surface design at critical interfaces disrupts the formation of interference fringes while maintaining the optical transmission properties needed for image brightness.
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
Effectively reduces visible interfering noise, improving image quality and maintaining the brightness of the enlarged virtual image displayed by two-dimensional scanning with coherent light beams.
Implementation Method 1
micro convex lenses which diverge the light beam
Implementation Method 2
curvature radius r of border surfaces between the micro convex lenses is smaller than a light wavelength λ
Data Source
Figure 1A~1C
Figure 2A~2B
Figure 3A~3C
AI summary
An image display device includes a light source, an imaging element to form an image with a light beam from the light source, and a lens array illuminated with the light beam forming the image for image display, in which lenses are arranged closely to each other. In which in the lens array a curvature radius of a surface of a border of neighboring lenses is set to be smaller than a wavelength of the light beam.