Movable Prism Layer for HUD Dark Band Suppression
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Solution Overview
Problem
Prismatic periodic structures in head-up displays cause visual artefacts such as dark bands and loss of image content due to refraction and internal reflection, which affect image quality.
Innovation Solution
A light control layer with moveable elongate structures, such as triangular prisms, is used to mitigate glare and reduce dark bands by oscillating between positions to allow continuous propagation of light replicas, minimizing image loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If prismatic periodic structures are used to control light in head-up displays, then light propagation is directed and glare is reduced, but visual artefacts such as dark bands and image content loss occur due to refraction and internal reflection
Solution Approach 1:
The patent applies the dynamics principle by making the light control layer moveable rather than fixed. The layer oscillates between two positions to dynamically control light propagation, allowing light replicas to pass through continuously without being blocked by stationary prismatic structures. This dynamic approach eliminates dark bands and prevents image content loss while maintaining glare reduction benefits.
Solution Approach 2:
The light control layer performs periodic oscillation between two positions at a frequency that creates a temporal averaging effect. This periodic motion ensures that over time, light replicas can propagate through the structure without encountering blocking surfaces, thereby eliminating visual artefacts like dark bands while maintaining the periodic glare suppression function.
2Speed
If prismatic periodic structures are used to control light, then light direction is controlled, but dark bands appear due to refraction and internal reflection
Solution Approach 1:
By making the light control layer moveable and oscillating, the patent transforms a static light-blocking structure into a dynamic one. The oscillation ensures that light replicas can pass through the structure at any given moment, preventing the formation of persistent dark bands while maintaining effective light direction control through the periodic positioning of the prismatic elements.
3Object-affected harmful factors
If a light control layer with elongate structures is introduced to reduce glare, then device complexity increases, but image quality is maintained through motion
Solution Approach 1:
The patent replaces complex multi-layer static optical structures with a single moveable light control layer that uses simple oscillating motion to achieve glare reduction. This mechanical substitution simplifies the overall device architecture while maintaining the desired optical performance, as the motion-based control is more efficient than complex static geometric arrangements.
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
The motion of the light control layer effectively reduces dark bands and image loss, maintaining image quality by ensuring continuous propagation of light replicas.
Implementation Method 1
by utilising an angled face of the cross-section of the structures to provide refraction, the angle of the light exiting the waveguide can be adjusted
Implementation Method 2
The first surface may be arranged to form the plurality of replicas of the spatially modulated light by wavefront division
Data Source
AI summary
A head-up display for a vehicle is provided. The head-up display comprises an optical component arranged to emit light from a first surface thereof. The head-up display further comprises a light control layer having a plurality of elongate structures and being arranged in cooperation with the optical component on an optical path between the first surface and an eye-box of the head-up display. Finally, the head-up display comprises a driver arranged to move the light control layer between a first position and a second position. The motion is on a plane parallel to a plane of the first surface.