Variable Lenslet Array for Uniform Illumination in Tilted HUDs
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Solution Overview
Problem
Conventional head-up displays suffer from non-uniform zone sizes and intensity due to the tilt of the LCD relative to the backlight, leading to a 'postcard' effect and issues with solar back-reflection and overheating.
Innovation Solution
A variable lens array with lenses of varying optical power is used to compensate for the tilt, ensuring uniform projection of light zones onto the LCD by adjusting beam angles based on the distance from the light emitters to the LCD.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the LCD is tilted relative to the backlight plane to prevent solar back-reflection and overheating, then thermal management and solar reflection are improved, but the zone sizes and intensity become non-uniform across the LCD
Solution Approach 1:
The patent applies local quality by varying the optical characteristics (focal length) of individual lenslets based on their position in the array. Lenslets closer to the LCD have different optical power than those farther away, creating localized adjustments that compensate for the tilt-induced non-uniformity. This allows each region of the backlight to be optimized independently for uniform zone projection onto the tilted LCD.
Solution Approach 2:
The patent changes the optical parameters (focal length, optical power) of the lenslets to compensate for the geometric effects of LCD tilt. By adjusting these parameters across the lens array, the system maintains uniform zone sizes and intensities despite the non-parallel arrangement, resolving the contradiction between thermal management requirements and illumination uniformity.
2Object-affected harmful factors
If the LCD is tilted relative to the backlight plane, then solar back-reflection is reduced, but the intensity distribution across the display becomes non-uniform
Solution Approach 1:
The patent implements local quality by assigning different optical characteristics to lenslets based on their spatial position. Lenslets in regions that would otherwise receive excessive or insufficient light due to tilt are given adjusted focal lengths, creating localized compensation that maintains overall intensity uniformity across the tilted LCD surface.
Solution Approach 2:
The patent modifies optical parameters of the lenslets to counteract the intensity non-uniformity caused by LCD tilt. By varying focal length and optical power across the array, the system achieves uniform illumination distribution while maintaining the beneficial tilted configuration for reducing solar back-reflection.
3Device complexity
If conventional lenslets with constant optical power are used, then the system structure is simple, but the projected zones vary in size and intensity across the LCD
Solution Approach 1:
The patent applies local quality by making each lenslet's optical characteristics position-dependent. Instead of using identical constant-power lenslets, the system employs lenslets with varying focal lengths tailored to their specific locations in the array, compensating for the tilt geometry and achieving uniform zone projection.
Solution Approach 2:
The patent changes the optical parameters of the lenslets from constant to variable based on position. This parameter variation across the lens array compensates for the non-parallel geometry between backlight and LCD, maintaining consistent zone sizes and intensities without requiring complex mechanical adjustments.
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
Achieves uniform illumination across the LCD, reducing the 'postcard' effect and improving image quality by maintaining consistent zone sizes and intensities despite the LCD tilt.
Implementation Method 1
A plurality of lenses are disposed between the first plane and the second plane. Each lens passes light from a respective one of the light emitters to a respective zone of the liquid crystal display.
Implementation Method 2
At least one mirror reflects light emitted by the liquid crystal display such that the reflected light is again reflected by a windshield of the motor vehicle
Implementation Method 3
At least one mirror reflects light emitted by the liquid crystal display such that the reflected light is again reflected by a windshield of the motor vehicle so as to be visible by a human driver of the motor vehicle as a virtual image
Data Source
AI summary
A head up display arrangement for a motor vehicle includes a picture generation unit having a plurality of light emitters conjunctively defining a first plane and each emitting light. A liquid crystal display defines a second plane that is nonparallel to the first plane. A plurality of lenses are disposed between the first plane and the second plane. Each lens passes light from a respective one of the light emitters to a respective zone of the liquid crystal display. Each lens has an optical characteristic that is dependent upon a distance between the respective one of the light emitters and the respective zone of the liquid crystal display. At least one mirror reflects light emitted by the liquid crystal display such that the reflected light is again reflected by a windshield of the motor vehicle to be visible by a human driver of the motor vehicle as a virtual image.