Through-Display Interferometric Sensing for Precise Proximity Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional through-display proximity sensors for electronic devices face challenges due to self-reflection and scattering of emitted light, leading to poor accuracy and precision in detecting objects nearby, causing unintended device behaviors such as unexpected touch screen enabling/disabling, display brightness changes, and speaker volume adjustments.
Innovation Solution
An interferometric optical sensing system is implemented, featuring a light emitter and photosensitive element optically coupled via a waveguide, operating as a heterodyne interferometer to determine object velocity and proximity by analyzing light reflections through the display, leveraging principles of optical field strength fading rather than intensity-based methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional reflective infrared sensor is used to detect objects through the display, then the sensor can operate through the display, but self-reflection and scattering of emitted light by the display reduces signal to noise ratio and measurement precision
Solution Approach 1:
The patent replaces conventional intensity-based detection with interferometric detection using a heterodyne interferometer. The system uses a light emitter to send modulated light through the display to an object, and a photosensitive element to detect the reflected light. The interferometric measurement of phase or frequency changes enables precise proximity and velocity detection despite self-reflection and scattering in the display medium.
Solution Approach 2:
The patent changes the detection parameter from light intensity to light phase or frequency. By using a heterodyne interferometer with modulated light emission and interferometric detection, the system measures phase shifts or frequency changes in the reflected light rather than intensity variations, thereby achieving high precision through-display sensing despite display-induced scattering and self-reflection.
2Productivity
If conventional intensity-based proximity sensing is used, then the system can detect object proximity, but the signal to noise ratio is poor leading to unintended device behaviors
Solution Approach 1:
The patent replaces intensity-based sensing with interferometric sensing. The heterodyne interferometer detects phase or frequency modulations in reflected light, providing superior signal-to-noise ratio and reliability for proximity detection compared to conventional intensity-based methods, thereby preventing unintended device behaviors.
Solution Approach 2:
The system uses a light emitter to send modulated light through the display to an object, and a photosensitive element to detect the reflected light. The interferometric measurement provides feedback on object proximity and velocity, enabling reliable detection and appropriate device responses.
3Measurement precision
If an interferometric optical sensing system with waveguide is implemented, then signal to noise ratio and measurement precision are significantly improved, but device complexity increases
Solution Approach 1:
The patent integrates the light emitter, optical waveguide, and photosensitive element into a unified interferometric sensing system. The waveguide optically couples the light emitter to the photosensitive element, forming a compact heterodyne interferometer that achieves high measurement precision while maintaining reasonable device complexity through component integration.
Solution Approach 2:
The optical waveguide serves as an intermediary component that efficiently couples light from the light emitter to the photosensitive element. The waveguide enables precise interferometric measurements by guiding the optical path while maintaining system compactness, thereby achieving high measurement precision without excessive complexity.
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 approach significantly improves signal-to-noise ratio, enabling more accurate and precise proximity and velocity sensing with reduced power consumption, allowing for detailed signal analysis and effective operation in low-power devices like wearables, and preventing unintended device interactions.
Implementation Method 1
a light emitter configured to emit light toward the object to illuminate the object
Implementation Method 2
receive light reflecting from the object
Implementation Method 3
an optical waveguide coupling the light emitter and the photosensitive element
Implementation Method 4
operating as an interferometric optical sensor or, more specifically, as a heterodyne interferometer
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An optical sensing system includes a transmitter side and a receiver side, and is configured to be positioned below a display of an electronic device. The transmitter side includes a light emitter. The receiver side includes an array of photodiodes. The light emitter of the transmitter side and the array of photodiodes of the receiver side are optically coupled via a waveguide. As a result of this construction, the optical sensing system can be operated as an interferometric optical sensor.