HUD Optical Shutter Control for Sunlight-Safe AR Visibility
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Solution Overview
Problem
Head-up displays (HUDs) using augmented reality (AR) face challenges in preventing sunlight damage to the display panel while maintaining user visibility of virtual images, as widening the optical path to accommodate larger display regions increases sunlight intrusion, and existing methods like changing the transmission window size are insufficient in blocking sunlight without obstructing the video light path.
Innovation Solution
A head-up display apparatus with a switching unit, such as a shutter, that controls the optical path between the video light and sunlight, periodically switching between light transmission and blocking states to minimize sunlight damage while ensuring user visibility of virtual images, using a combination of PWM control for the light source and shutter operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the opening on the optical path is widened to widen the display region, then the display region is widened, but sunlight is more likely to enter through the optical path and damage the display panel
Solution Approach 1:
The optical path control is segmented into multiple independent switching units (shutters) positioned at different locations. Each shutter can independently block sunlight from different angles while maintaining the wide opening for video light projection. This segmentation allows the system to maintain a wide display region while providing targeted protection against sunlight intrusion from various directions.
2Object-affected harmful factors
If the optical path of sunlight is blocked to prevent damage, then sunlight damage is prevented, but the optical path of video light is also blocked and the user cannot visually recognize the virtual image
Solution Approach 1:
The shutters are designed to dynamically switch between open and closed states based on real-time detection of sunlight position and intensity. The control unit continuously monitors environmental conditions and adjusts the shutter states accordingly, ensuring that sunlight blocking is activated only when necessary while maintaining continuous visibility of the virtual image during normal operation.
Solution Approach 2:
The system uses sunlight detection units to detect the position and intensity of sunlight in advance before it can damage the display panel. Based on this preliminary detection, the control unit proactively activates the appropriate shutters to block incoming sunlight, preventing damage before it occurs while minimizing interruption to the video light path.
3Area of stationary object
If the transmission window size is changed in accordance with the display image size, then the display region is optimized, but sunlight concentration spots remain and sufficient protection cannot be achieved
Solution Approach 1:
Instead of uniformly controlling the entire transmission window, the system implements localized quality control by positioning multiple shutters at specific locations where sunlight concentration is most likely to occur. Each shutter targets specific vulnerable areas, providing localized protection against sunlight concentration while maintaining optimal transmission window size for the display region.
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 solution reduces the time users cannot see virtual images while preventing sunlight damage to the display panel, offering reliable protection and maintaining visibility by strategically controlling the shutter and light source in conjunction with the mirror's projection mode.
Implementation Method 1
The switching unit is provided on an optical path of the video light and switches to an optical path forming state in which the optical path of the video light is formed or an optical path non-forming state in which the optical path of the video light is not formed
Implementation Method 2
The video light projector projects the video light emitted from the video display to a display region so as to be reflected, thereby displaying a virtual image in front of the transportation
Data Source
AI summary
A head up display apparatus capable of reducing a time period during which a user cannot visually recognize a virtual image while preventing damage due to sunlight and a control method thereof are provided. According to the present invention, it is possible to contribute to “Goal 3: Ensure healthy lives and promote well-being for all at all ages” in the Sustainable Development Goals (SDGs). A video display 35 displays a video and emits video light of the displayed video. A mirror (video light projector) M1 projects the video light emitted from the video display 35 to a display region 5 so as to be reflected, thereby causing a user to visually recognize the projected video light as a virtual image. A shutter 68 is provided on an optical path 30 of the video light and switches to an optical path forming state in which the optical path of the video light is formed or an optical path non-forming state in which the optical path of the video light is not formed.