HUD Light Guide Prism Layout for Narrow-Angle Light Extraction
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Solution Overview
Problem
Current optical systems for head-up displays in vehicles face challenges in achieving high light extraction efficiency while maintaining a narrow viewing angle and high light intensity, often resulting in light leakage and reduced performance.
Innovation Solution
The optical system incorporates a light guide member with a prism structure that reflects light directly from the first surface to the second surface, minimizing repeated reflections and using light control members to control the divergence angle of light, thereby enhancing light extraction efficiency and reducing leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If light is reflected multiple times within the light guide member to increase light extraction, then light extraction efficiency improves, but light leakage increases and viewing angle control deteriorates
Solution Approach 1:
The light guide member is divided into multiple regions with different reflection characteristics. A first light guide member with high reflection rate is positioned in a specific region, while a second light guide member with lower reflection rate is positioned in another region. This segmentation allows different parts of the system to perform different functions: one region maximizes light extraction while another region controls light direction and prevents leakage, thereby resolving the contradiction between extraction efficiency and leakage control.
2Illumination intensity
If the viewing angle is narrowed to improve image quality, then light intensity concentrates, but light extraction efficiency decreases
Solution Approach 1:
Different regions of the light guide member are assigned different reflection rates according to their specific functional requirements. The first light guide member with high reflection rate (80% or higher) is placed in a region where light extraction is prioritized, while the second light guide member with lower reflection rate is placed in a region where viewing angle control is prioritized. This local differentiation of optical properties allows the system to simultaneously achieve high light extraction efficiency in certain areas and narrow viewing angle control in other areas, resolving the contradiction between light intensity concentration and extraction efficiency.
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 significantly increases light extraction efficiency, maintaining a narrow viewing angle and high light intensity, while eliminating the need for additional optical elements, thus improving the overall performance of the head-up display.
Implementation Method 1
The prism is provided for the first surface and reflects, toward the second surface, the light passing inside the light guide member
Implementation Method 2
a light guide member having: an incident surface on which light is incident; and a first surface and a second surface facing each other. The second surface is a light emergent surface
Data Source
AI summary
An optical system includes a light guide member having a light incident surface, a first surface, and a light emergent surface facing the first surface; and a prism provided in the first surface for reflecting light passing inside the light guide member towards the light emergent surface. The light guide member includes a direct optical path, along which the light that has entered the light guide member through the incident surface is directly reflected from the prism and allowed to emerge from the light emergent surface. At least one of the first surface or the light emergent surface includes a luminous intensity distribution control member configured to control a luminous intensity distribution of light to be extracted from the light emergent surface. The luminous intensity distribution control member includes a Fresnel lens.