HUD Light Source Layout for Uniform Luminance Distribution
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Solution Overview
Problem
Existing vehicular head-up displays 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 with a prism-shaped multi-reflection member and a substrate with LED sources arranged in a specific matrix configuration, where the ratio of LED sources in the longer direction to those in the shorter direction is optimized to ensure uniform luminance distribution, is used in conjunction with a liquid crystal element to project images onto a windshield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If light sources are arranged in a matrix on a substrate to illuminate a liquid crystal element, then the head-up display can be constructed with a practical light source configuration, but the luminance distribution becomes non-uniform
Solution Approach 1:
A light guiding member with a specific refractive index is introduced as an intermediary between the LED light sources and the liquid crystal element. This light guiding member receives light from the LEDs and guides it to the liquid crystal element, acting as a mediator that transforms the non-uniform light distribution from the matrix arrangement into a more uniform illumination pattern on the display surface.
Solution Approach 2:
The patent optimizes specific parameters including the refractive index of the light guiding member, the dimensions and arrangement of LED light sources, and the geometric configuration of the light guiding member. By adjusting these parameters, the system achieves uniform luminance distribution while maintaining the practical matrix configuration of light sources on the substrate.
2Device complexity
If a simple light source arrangement is used, then the device complexity is reduced, but the luminance uniformity deteriorates
Solution Approach 1:
The light guiding member serves as a relatively simple intermediary component that bridges the simple matrix light source arrangement and the liquid crystal element. This single additional component provides the necessary light redistribution function without introducing complex mechanical or optical systems, thus maintaining low device complexity while improving luminance uniformity.
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 and consistency of the images projected in vehicular head-up displays.
Implementation Method 1
a prism-shaped multi-reflection member that has: an entrance surface; an emission surface; and a reflective surface that connects the entrance surface and the emission surface on an inner surface of the multi-reflection member
Data Source
AI summary
A light source unit used for a vehicular head-up display includes a prism-shaped multi-reflection member and a substrate. The multi-reflection member has: an entrance surface; an emission surface; and a reflective surface connecting the entrance surface and the emission surface. The substrate faces the entrance surface and is provided with a plurality of light sources mounted in a matrix. A ratio Ra=A/B or a ratio Rc=a/b is larger than a ratio Rb=C/D, where A and B is the number of the light sources provided in a longer and shorter direction of the entrance surface, respectively, C and D is a longer and shorter dimension of the emission surface, respectively, and a and b is the sum of lengths of light-emitting surfaces of the plurality of light sources in the longer and shorter direction of the entrance surface, respectively.