Head-Mounted Display Projector Positioning for Stray Light Reduction
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Solution Overview
Problem
Conventional head-mounted display devices face issues with stray light causing noise and reduced visibility due to the incidence of external light, and difficulty in increasing the angle of view due to the small size of optical components, which affects the see-through function and user experience.
Innovation Solution
A head-mounted display device design where a projector with an optical element is positioned in the visual fields of both eyes, ensuring a shorter distance between the tangency point of the projector's outline and the pupillary distance, allowing for a larger exit surface and improved see-through functionality even with a light shielder, and incorporating a light emitting element to reduce ghost light and enhance visibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a half mirror is used as an optical component to achieve see-through function, then external light can penetrate through, but stray light causes noise and reduced visibility
Solution Approach 1:
The patent extracts the harmful function of the half mirror by removing it from the optical path. Instead of using a half mirror that reflects and transmits light, the invention uses a fully transparent window that only transmits light, eliminating the stray light reflection problem while maintaining see-through functionality.
Solution Approach 2:
The patent converts the potential harm of light blocking into a benefit by using a transparent window that allows all light to pass through. The window's transparency transforms what could be a light-blocking obstacle into a light-transmitting element that maintains external visibility without causing stray light noise.
2Object-affected harmful factors
If the optical component is made smaller than the pupil diameter to achieve see-through function, then the angle of view is limited, but making it larger causes obstruction of external view
Solution Approach 1:
The patent changes the critical parameter from component size relative to pupil diameter to component transparency. By making the window fully transparent rather than using a half mirror or small component, the system achieves both wide angle of view and minimal obstruction of external scenery simultaneously.
3Object-affected harmful factors
If a light shielder is added to reduce stray light, then ghost light is reduced, but the visual field for surroundings is obstructed
Solution Approach 1:
The patent removes the light shielder component entirely from the design. Instead of adding a shielder that blocks light, the invention uses a transparent window that naturally prevents stray light and ghosting through its optical properties, eliminating the need for additional light-blocking elements that would obstruct the visual field.
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 design achieves enhanced visibility and increased angle of view by minimizing stray light and ghosting, while maintaining the see-through function without obstructing the user's view, thereby improving the overall display device performance.
Implementation Method 1
an optical element that projects an image on one of left and right eyes of an observer
Data Source
AI summary
A display device of the disclosure includes a projector including optical elements to project images on left or right eye of an observer and a frame connected to the projector for mounting on the observer. With the frame mounted on the observer, at least part of the projector is placed in visual fields of the eyes, and length from tangent point between leftmost one among lines of sight of the left eye overlapping outline of at least the part and the outline to intersection between an imaginary line through the tangent point parallel to direction of pupillary distance of the observer and rightmost one among lines of sight of the right eye overlapping the outline is shorter than the pupillary distance in a top plan view of the display device.