Rotating Narrow-Angle Diffuser for Eye-Tracking Display
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Solution Overview
Problem
Directional backlit display devices with eye tracking are challenged by limited viewing angles due to a small projection area, causing observers to miss parts of the image when moving their heads or being replaced by others, as existing diffusers do not effectively adjust to maintain image visibility across various positions.
Innovation Solution
A directional backlit display device incorporating a reflective narrow-angle diffuser with an array of micro curved mirrors, controlled by a drive module and eye tracking device, which adjusts the projection area by rotating the diffuser to maintain a uniform directional light beam and image projection across a wider area, ensuring observers see a full image from various positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a reflective narrow-angle diffuser with micro curved mirrors is used to concentrate light in a preset direction, then the brightness of the image is significantly increased, but the projection area becomes very small (eye box), causing observers to miss parts of the image when moving their heads or being replaced by others
Solution Approach 1:
The patent applies the dynamics principle by making the reflective narrow-angle diffuser rotatable around a shaft. The diffuser's rotation angle is dynamically adjusted based on eye tracking information, allowing the projection area to move and track the observer's eye position. This transforms the originally static, fixed projection area into a dynamic one that can adapt to different viewing positions, resolving the contradiction between concentrated brightness and limited projection area.
Solution Approach 2:
The patent implements feedback by using an eye tracking device to detect the observer's eye position and feeding this information back to the control module. The control module then adjusts the rotation angle of the reflective narrow-angle diffuser accordingly. This closed-loop feedback system ensures the projection area continuously tracks the eye position, maintaining full image visibility while preserving the high brightness concentration achieved by the narrow-angle diffuser.
2Ease of manufacture
If a flat-surfaced reflector is used with a smooth and flat surface, then the manufacturing process is simple, but the viewing angles are limited and there is no diffusion effect
Solution Approach 1:
The patent applies segmentation by dividing the reflector surface into multiple independent micro curved mirrors arranged in an array. Each micro curved mirror can be manufactured with standard curvature, simplifying the manufacturing process compared to creating a complex continuously variable surface. Meanwhile, the collective array of segmented mirrors achieves the desired narrow-angle diffusion effect, resolving the contradiction between manufacturing simplicity and viewing angle adaptability.
Solution Approach 2:
The patent implements local quality by giving each micro curved mirror a specific curvature and orientation tailored to its position in the array. This local customization of mirror properties allows the overall system to achieve precise control over light diffusion angles while maintaining relatively simple individual mirror manufacturing. The local quality variation across the array enables the narrow-angle diffusion effect without requiring complex manufacturing of each individual mirror.
3Adaptability or versatility
If a projection screen with a wide scattering surface is used to diffuse light in all directions, then observers from all angles can see the projected image, but the brightness of the image observed is greatly reduced
Solution Approach 1:
The patent applies dynamics by replacing the static wide-scattering surface with a dynamic system consisting of a rotatable reflective narrow-angle diffuser. Instead of constantly diffusing light in all directions, the system dynamically adjusts the diffusion direction to track the observer's eye position. This dynamic adjustment maintains high image brightness by concentrating light in a narrow angle while adapting the viewing direction, resolving the contradiction between wide viewing angle and high brightness.
Solution Approach 2:
The patent implements parameter changes by varying the rotation angle of the reflective narrow-angle diffuser based on eye tracking data. The diffusion angle parameter remains narrow (maintaining brightness), but the direction parameter changes dynamically to follow the observer's eye position. This parameter adjustment strategy allows the system to achieve wide effective viewing coverage without sacrificing image brightness, unlike the static wide-scattering surface approach.
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 solution provides a high-brightness, uniform image across a larger viewing area, allowing multiple observers to see the entire image without the need for frequent adjustments, as the diffuser dynamically adjusts to track the observer's eye position, enhancing the viewing experience by maintaining image continuity.
Implementation Method 1
The array of the plurality of micro curved mirrors of the reflective narrow-angle diffuser reflect the light and uniformly diffuses the light with a narrow diffusion angle
Implementation Method 2
driving the reflective narrow-angle diffuser to rotate to change a projecting direction of the uniform directional light beam
Data Source
AI summary
A directional backlit display device includes a light source module, a reflective narrow-angle diffuser, a backlit display device panel, an eye tracking device, and a controller. The diffuser includes a shaft and is utilized to reflect and uniformly diffuse the light to provide a uniform directional light beam. The backlit display device panel is included on the projecting optical path of the uniform directional light beam. The uniform directional light beam illuminates an image displayed on the backlit display device panel and projects to a projection area. The controller receives an eye position information from the eye tracking device and determines a coordinate. The controller determines a corrective projection area when the coordinate deviates from the projection area, and the drive module rotates the reflective narrow-angle diffuser around an axis of the shaft according to the corrective projection area, so the image projection area moves with the eye.