Head-Up Display Backlight Lens Array Asymmetry
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Solution Overview
Problem
Head-up display (HUD) devices experience uneven illumination and reduced light use efficiency due to aberrations in the condensing means, leading to luminance uniformity issues in the display image, especially when the focal distance of the projection optical system differs in longitudinal and lateral directions, causing convergence degradation and luminance variations.
Innovation Solution
A HUD device with a backlight unit comprising a light source, a lens array, and a condensing means with different focal distances in longitudinal and lateral directions, where the lens array has varying light distribution angles between the center and periphery, and the condensing means includes toroidal or free curved surfaces to correct focal distance discrepancies and optimize light distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional condensing means with equal focal distances in longitudinal and lateral directions is used, then the device structure is simple and manufacturing is easier, but uneven illumination occurs in the display area and light use efficiency is lowered
Solution Approach 1:
The condensing means employs asymmetric lens designs where the focal distance in the longitudinal direction differs from the focal distance in the lateral direction. This asymmetry compensates for the asymmetric light distribution characteristics of the lens array, ensuring uniform illumination across the display area while maintaining manufacturing feasibility through standardized asymmetric lens fabrication processes.
Solution Approach 2:
The condensing means uses multiple lenses with locally optimized focal distances tailored to specific regions of the display area. By adjusting the focal distance of individual lenses or lens groups according to their position, the system achieves uniform illumination across different zones while allowing for modular manufacturing and assembly.
2Manufacturing precision
If the focal distance of the projection optical system is adjusted for longitudinal direction, then convergence in that direction is improved, but luminance uniformity in lateral direction deteriorates
Solution Approach 1:
The condensing means employs asymmetric lens designs where the focal distance in the longitudinal direction differs from the focal distance in the lateral direction. This asymmetry compensates for the asymmetric light distribution characteristics of the lens array, ensuring uniform illumination across the display area while maintaining manufacturing feasibility through standardized asymmetric lens fabrication processes.
Solution Approach 2:
The system uses multiple lenses with different focal distance parameters optimized for their respective positions and functions. By varying the focal distance parameter across different lenses or lens groups, the system simultaneously achieves precise convergence in the longitudinal direction and uniform luminance distribution in the lateral direction.
3Area of stationary object
If the irradiation range is expanded from positions far from the optical axis, then coverage of the display area is improved, but light use efficiency is lowered
Solution Approach 1:
The condensing means uses multiple lenses with locally optimized focal distances tailored to specific regions of the display area. By adjusting the focal distance of individual lenses or lens groups according to their position, the system achieves uniform illumination across different zones while allowing for modular manufacturing and assembly.
Solution Approach 2:
The system uses multiple lenses with different focal distance parameters optimized for their respective positions and functions. By varying the focal distance parameter across different lenses or lens groups, the system simultaneously achieves precise convergence in the longitudinal direction and uniform luminance distribution in the lateral direction.
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 effectively controls uneven illumination and maintains high convergence and luminance uniformity of the display image by adjusting the focal distances and light distribution angles, improving light use efficiency and image quality across the entire display area.
Implementation Method 1
a lens array which divides light emitted from the light source, and generates a plurality of images of the light source
Implementation Method 2
a condensing means which condenses light emitted from an image of the light source to correspond to a display area of the display element
Data Source
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AI summary
Provided is a head-up display device capable of suppressing uneven illumination in a display area of a display element due to the aberration of a light-gathering means. A head-up display device 100 projects display light L emitted from a display 3 provided with a backlight unit 1 and a liquid crystal display element 2 on a viewpoint area of a viewer via a projection means and causes an image represented by the display light L to be visually recognized. The backlight unit 1 is provided with: a light source 10 which emits light I for illuminating the liquid crystal display element 2; a lens array 40 in which a plurality of lenses are disposed, and which divides the light I emitted from the light source 10 and generates a plurality of images of the light source 10; and light gathering means 51, 52 which gather the light I emitted from the images of the light source 10 such that the light corresponds to a display area of the liquid crystal display element 2, wherein the lens array 40 is configured such that the light distribution angles of the lenses at the periphery thereof are different from the light distribution angles of the lenses at the center thereof.