Through-Display Depth Sensing Using Diffraction-Aware Light Patterns
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Solution Overview
Problem
Existing 3D imaging systems face challenges in functioning beneath transparent or translucent displays due to microstructure interference, low light transmission, and diffraction effects, which hinder reliable depth measurement.
Innovation Solution
A display device with an illumination source projecting an illumination pattern, an optical sensor capturing reflection features, and an evaluation device analyzing beam profiles to generate a depth map, utilizing a translucent display with integrated components to minimize diffraction interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a translucent display is used for 3D imaging, then the display can be integrated without empty windows, but the microstructure causes diffraction effects that degrade measurement quality
Solution Approach 1:
The patent converts the harmful diffraction grating effect caused by the display's microstructure into a beneficial feature by using it for wavelength multiplexing. The diffraction separates different wavelengths spatially, allowing the system to use multiple wavelengths for depth measurement simultaneously, thereby transforming the previously problematic diffraction into a useful mechanism for enhancing measurement capability
Solution Approach 2:
The system changes the wavelength parameter of the illumination light to exploit the diffraction effect. By using multiple wavelengths and analyzing their different diffraction patterns, the system can distinguish between real objects and diffraction artifacts, thereby maintaining measurement precision despite the presence of the display's microstructure
2Area of stationary object
If traditional structured light with many projection points is used, then coverage is improved, but light transmission through the display becomes insufficient
Solution Approach 1:
The patent changes the wavelength parameter of the illumination light to exploit the diffraction effect. By using multiple wavelengths and analyzing their different diffraction patterns, the system can distinguish between real objects and diffraction artifacts, thereby maintaining measurement precision despite the presence of the display's microstructure
3Illumination intensity
If high-power projection is used to compensate for low light transmission, then sufficient light reaches the sensor, but ambient light robustness deteriorates
Solution Approach 1:
The patent uses wavelength as a distinguishing parameter, illuminating the scene with multiple wavelengths and analyzing their different diffraction patterns. This allows the system to identify and filter out ambient light interference by recognizing the characteristic diffraction signatures of the projected wavelengths, thereby maintaining ambient light robustness without requiring excessive projection power
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
Enables reliable depth measurement through displays with reduced technical effort and resource requirements, improving ambient light robustness and reducing the need for high-power projection.
Implementation Method 1
at least one optical sensor having at least one light sensitive area, wherein the optical sensor is configured for determining at least one first image comprising a plurality of reflection features generated by the scene in response to illumination by the illumination features
Implementation Method 2
The microstructure of the transparent or translucent display works like a diffraction grating structure for laser light. As most of the projectors of structured light imagers are based on a laser source that projects a well-defined dot pattern, this pattern experiences a grating effect of the display and every single spot of the dot pattern will show higher diffraction orders
Data Source
AI summary
Disclosed herein is a display device includingan illumination source configured to project an illumination pattern including a plurality of illumination features on a scene;a camera configured to capture a first image of the scene under the illumination pattern;a translucent display, where the camera is placed in direction of propagation of the illumination pattern in front of the display; anda processor configured to identify the reflection features and their brightness from the first image, match reflection features with corresponding illumination features, and classify a reflection feature being matched with an illumination feature as a real feature or as a false feature using its brightness.