Head-Up Display Dual Diffusion Plate Visibility
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Solution Overview
Problem
Conventional head-up display devices have limited visibility of virtual images due to the reciprocal action of light source image expansion by the condensing unit, which narrows the range in which a bright virtual image is visible to an occupant.
Innovation Solution
The head-up display device includes multiple light emitting devices aligned along one direction, a first diffusion plate to diffuse illumination light, a cylindrical lens as a condensing unit to exert a condensing action in the vertical direction, and a second diffusion plate on the optical path between the condensing unit and the image forming unit to further diffuse the illumination light, ensuring efficient illumination and expanding the visibility range of the virtual image.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a condensing unit is used to condense illumination light in the vertical direction, then illuminance uniformity on the illumination target surface is improved, but the spreading of the light flux of display light is reduced, narrowing the visible range of the virtual image
Solution Approach 1:
The patent divides the diffusion function into two separate diffusion plates positioned at different locations in the optical path. The first diffusion plate is positioned before the condensing unit to diffuse light from light emitting devices, while the second diffusion plate is positioned after the condensing unit to diffuse the condensed light again. This segmentation allows each diffusion plate to perform its specific function without interfering with the condensing action, thereby maintaining both illuminance uniformity and light flux spreading for wide virtual image visibility.
2Illumination intensity
If light emitting devices are aligned along one direction with a diffusion plate, then a surface light source is formed improving illuminance distribution, but the light flux spreading is reduced due to reciprocal action of condensing unit
Solution Approach 1:
The patent introduces a second diffusion plate in the vertical direction (perpendicular to the alignment direction of light emitting devices) after the condensing unit. This adds another dimensional diffusion action that compensates for the light flux spreading reduction caused by the condensing unit's vertical condensing action. The combination of horizontal diffusion (first diffusion plate) and vertical diffusion (second diffusion plate) achieves comprehensive illuminance distribution while maintaining light flux spreading in all directions for wide virtual image visibility.
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 enhances the visibility of the virtual image by reducing illumination unevenness and preventing the narrowing of the visible range, while maintaining efficient illumination on the target surface, thus providing a head-up display device with high visibility.
Implementation Method 1
a first diffusion plate configured to diffuse the illumination light emitted from each of the light emitting devices
Implementation Method 2
a condensing unit configured to exert a condensing action on the illumination light, which is diffused with the first diffusion plate, in a vertical direction perpendicular to the alignment direction
Implementation Method 3
a second diffusion plate located on an optical path between the condensing unit and the image forming unit. The second diffusion plate is configured to again diffuse the illumination light condensed with the condensing unit
Data Source
AI summary
Light emitting devices are aligned along one alignment direction. A first diffusion plate diffuses the illumination light from each of the light emitting devices. A condensing unit exerts a condensing action on the illumination light diffused with the first diffusion plate in a vertical direction perpendicular to the alignment direction. An image forming unit has an illumination target surface illuminated with the illumination light, which is condensed with the condensing unit, and allows a part of the illumination light incident on the illumination target surface to pass therethrough to form the image and to emit display light of the image as a light flux. A second diffusion plate is located on an optical path between the condensing unit and the image forming unit to again diffuse the illumination light condensed with the condensing unit and to cause the diffused illumination light to incident on the illumination target surface.