HUD Light Source Layout for Uniform Windshield Image Brightness
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Solution Overview
Problem
Existing vehicular head-up displays (HUDs) face challenges in achieving uniform luminance distribution in the light emitted by their light source units, which affects the quality of the projected images.
Innovation Solution
A light source unit featuring a prism-shaped multi-reflection member with a substrate-mounted LED array, where the ratio of LED numbers and lengths in the longer and shorter directions is optimized to ensure uniform light distribution, ensuring that light is emitted with consistent intensity across the emission surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If light sources are arranged in a conventional configuration on the substrate, then the device complexity is reduced and ease of manufacture is improved, but the luminance distribution uniformity deteriorates
Solution Approach 1:
The patent applies local quality by arranging light sources with different spatial densities in different regions of the substrate. Specifically, the ratio Ra (number of light sources in longer direction / number of light sources in shorter direction) is made larger than ratio Rb (emission surface longer dimension / shorter dimension), creating non-uniform local distribution that compensates for optical path differences and achieves uniform overall luminance distribution on the emission surface.
Solution Approach 2:
The patent changes the arrangement parameters of light sources (numbers A and B in different directions) to optimize luminance distribution. By controlling the ratio Ra > Rb, the patent adjusts the spatial distribution parameters of light sources to compensate for optical path length variations, thereby achieving uniform luminance without complex additional optical components.
2Manufacturing precision
If a prism-shaped multi-reflection member is added to optimize light distribution, then the luminance distribution uniformity is improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent employs asymmetry in the prism-shaped multi-reflection member, where the reflective surfaces are configured with specific asymmetric angles and orientations. This asymmetric geometry is designed to compensate for the non-uniform light source distribution (Ra > Rb) and achieve uniform luminance distribution on the emission surface, resolving the contradiction between improved uniformity and manufacturing complexity.
3Manufacturing precision
If the ratio of light source numbers in different directions is optimized (Ra > Rb), then the luminance distribution uniformity is improved, but the light source configuration becomes more complex
Solution Approach 1:
The patent optimizes the arrangement parameters of light sources by setting ratio Ra (A/B) larger than ratio Rb (C/D), where A and B are the numbers of light sources in the longer and shorter directions respectively. This parameter optimization achieves uniform luminance distribution by compensating for optical path differences in different directions, while maintaining a relatively simple matrix arrangement configuration.
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 configuration results in a more uniform luminance distribution, enhancing the quality of the images projected onto the windshield, thereby improving the overall performance of the head-up display.
Implementation Method 1
a reflective surface that connects the entrance surface and the emission surface on an inner surface of the multi-reflection member
Implementation Method 2
a liquid crystal element; and the light source unit described above
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A light source unit (60) used for a vehicular head-up display according to the present invention is provided with: a tubular multi-reflection member (61) which connects an entrance plane (63) and an exit plane (64) and which has a reflecting plane (66) provided on an inner surface thereof; and a substrate (62) which is disposed so as to face the entrance plane (63) and on which a plurality of light sources (65) are mounted in a matrix configuration. The ratio Ra = A/B between the number A of light sources (65) disposed in a long-axis direction (X) of the entrance plane (63) and the number (B) of light sources (65) disposed in a short-axis direction (Y) of the entrance plane (63) is configured to be greater than the ratio Rb = C/D between the long-axis dimension C and the short-axis dimension D of the exit plane (64).