HUD Screen Main Beam Orientation for Brightness
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Solution Overview
Problem
Existing image projection devices for head-up displays in vehicles face inefficiencies due to limited installation space, leading to insufficient light transmission and uneven illumination, as the etendue of the imager is not adequately matched with the projection device, resulting in a dark or dim image.
Innovation Solution
The device optimizes image projection by aligning the main beam directions of the screen to direct maximum intensity light towards the entrance pupil of the second projection device, using a curved or segmented screen with micro-lenses to ensure efficient light transmission and minimize light loss, and optionally tilting the screen to prevent reflections and enhance compactness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a screen is used to increase the solid angle of light emission, then the etendue of the projection device is improved, but light is lost because it does not reach the entrance pupil of the second projection device
Solution Approach 1:
The patent applies local quality by differentiating the screen's radiation characteristics across different spatial regions. The screen is designed to radiate light with direction-dependent intensity, where the main beam directions correspond to maximum intensity. This ensures that light is preferentially directed toward the entrance pupil of the second projection device, resolving the contradiction between increasing etendue and minimizing light loss.
2Adaptability or versatility
If a screen is used to increase the solid angle, then light guidance is improved, but uneven illumination of the entrance pupil occurs causing brightness variations
Solution Approach 1:
The patent addresses brightness uniformity by designing the screen to have spatially varying radiation characteristics. Different regions of the screen (central vs. edge regions) are configured to direct their main beam directions appropriately, ensuring uniform illumination across the entrance pupil and eliminating brightness variations during eye movement.
3Volume of moving object
If the imager size is kept small for limited installation space, then device compactness is improved, but the etendue becomes insufficient to fill the projection device
Solution Approach 1:
The patent introduces a screen as an intermediary element between the imager and the second projection device. This screen acts as a mediator that increases the etendue by radiating light over a larger solid angle, allowing a compact imager to effectively fill the projection device's etendue requirements without increasing overall device size.
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 approach enhances the projection efficiency by ensuring maximum intensity light is transmitted to the display area, providing brighter and more uniform illumination, while also allowing for a more compact device design.
Implementation Method 1
a screen (5) onto which the first projection device projects the intermediate image
Implementation Method 2
using a curved or segmented screen with micro-lenses to ensure efficient light transmission
Data Source
AI summary
Device (1) for projecting an image into a display area (2), with an imager (31) generating the picture, a first projection device (30) for generating a real intermediate image (R), a screen (5) onto which the first projection device (32) projects the intermediate image (R) and to a second projection device (9) projecting the intermediate image (R) into the display area (2). In order to project the image with the least possible loss of brightness, the invention provides that main beam directions (H, H′, H″) of the screen (5) point into an entrance pupil (20) of the second projection device (9).