HUD Direction-Selective Light Filter Reduces Reflection
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Solution Overview
Problem
Existing HUD systems face issues with reflection of ambient light from the display device back into the driver's eyes, degrading user experience and causing the image display device to heat up.
Innovation Solution
A direction-selective light filter is placed in the light path between the image display device and the reflecting element, featuring light guiding channels that allow imaging light cones to pass through while blocking reflection light cones, thereby reducing ambient light reflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a direction-selective light filter is added to block reflection light cones, then the harmful reflection is reduced, but the device complexity increases
Solution Approach 1:
A direction-selective light filter is introduced as an intermediary component between the image display device and the reflecting element. This filter selectively transmits imaging light cones while blocking reflection light cones, thereby reducing harmful reflections without requiring fundamental changes to the existing HUD architecture.
Solution Approach 2:
The light filter is structured with multiple light guiding channels that are segmented to correspond with individual pixels or groups of pixels on the display device. Each channel is configured to transmit only light within a specific angular range, enabling precise control over which light paths are permitted while blocking others.
2Illumination intensity
If light guiding channels are configured to block reflection light cones, then the contrast ratio is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The light guiding channels are designed with specific geometric parameters (width, depth, angle) that are optimized to match the angular characteristics of the imaging and reflection light cones. By carefully controlling these parameters during manufacturing, the system achieves high contrast ratios while maintaining feasible manufacturing tolerances.
Solution Approach 2:
The light filter may be constructed using composite materials or multi-layer structures that provide both the necessary optical properties and structural integrity. This allows for more relaxed manufacturing tolerances while still achieving the required precision in light path control.
3Temperature
If the light filter blocks reflection light cones, then the heating of the image display device is reduced, but the device complexity increases
Solution Approach 1:
The light filter is designed to convert the harmful reflection light cones into a beneficial function by directing them away from the display device. The blocked reflection light is effectively discarded, preventing it from heating the display, while the transmitted imaging light continues to form the desired image.
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 solution significantly reduces distracting reflections, enhances the contrast ratio of the HUD system's image, and minimizes the heating of the image display device.
Implementation Method 1
a plurality of light guiding channels is formed in the direction-selective light filter, each of the channels being configured to substantially pass imaging light cones entering the respective channel
Implementation Method 2
each of the channels being configured to substantially pass imaging light cones entering the respective channel, and to substantially block reflection light cones reflected by the image display device
Data Source
AI summary
The invention relates to a HUD system (100) with reduced reflection comprising an image display device (1) and a reflecting element (3) which are fixed and angled relative to each other, the image display device (1) being adapted to generate imaging light cones (11) radiating from points of an image generated thereby and reflected from the reflecting element (3), which imaging light cones (11) have their axes (T) pointing towards a designed detection point (23a) after reflection from the reflecting element (3), and wherein the imaging light cones (11) illuminate a designed detection area (23) in a plane passing through the detection point (23a), and wherein the HUD system (100) comprises a direction-selective light filter (20) arranged in the light path between the image display device (1) and the reflecting element (3), in which direction-selective light filter (20) a plurality of light guiding channels (22) passing through the direction-selective light filter (20) are arranged such that each of the channels (22) is configured in such a way as to be substantially transparent to imaging light cones (11) entering that channel (22), and to substantially block reflection light cones (12) reflected by the image display device (1) towards the reflecting element (3), which have axes (D) at different angles to the axes (T) of the imaging cones (11), wherein the image display device (1) is configured as a screen (2) closing an angle α with the reflecting element (3), and in that the light guiding channels (22) are arranged in the direction-selective light filter (20) in such a way that the period distance (p) defined by the width (h) and the wall thickness (w) of the light guiding channels (22) is at most one fifth or at least five times the pixel size of the screen (2).The invention also relates to a method for reducing the reflection of a HUD system (100).