Self-Mixing Interferometry Sensor Module for Buttonless Motion Control
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Solution Overview
Problem
Existing electronic devices face challenges with mechanical buttons that require space, are prone to wear, and pose risks of dust and water penetration, while optoelectronic modules are bulky due to the need for multiple components like light emitters and photodiodes.
Innovation Solution
A self-mixing interferometry sensor module using a light emitter with a cavity resonator and an electronic control unit to detect movements based on self-mixing interference, eliminating the need for collimation optics and photodiodes, and enabling gesture and finger movement control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If mechanical buttons are integrated into the housing, then control functionality is provided, but device space is consumed and complexity increases
Solution Approach 1:
The patent replaces mechanical buttons with an optoelectronic sensor module that detects finger movements through optical interference. This substitution eliminates the need for physical buttons, openings in the housing, and associated mechanical components, thereby saving device space while maintaining control functionality.
Solution Approach 2:
The invention extracts the control functionality from the mechanical button structure and relocates it to an optoelectronic detection system. By taking out the mechanical button and its required housing openings, the design achieves space efficiency while preserving the essential user interaction capability.
2Ease of operation
If mechanical buttons are integrated into the housing, then control functionality is provided, but reliability decreases due to wear and water/dust penetration risks
Solution Approach 1:
The patent replaces mechanical buttons with an optoelectronic sensor module that detects finger movements through optical interference. This substitution eliminates mechanical wear from springs and moving parts, and removes openings that could allow water and dust penetration, thereby significantly improving device reliability while maintaining control functionality.
Solution Approach 2:
The invention eliminates components with limited lifetimes (mechanical springs and buttons) in favor of solid-state optoelectronic components that have no moving parts and do not wear out, thereby extending device lifetime and improving reliability.
3Adaptability or versatility
If optoelectronic modules with multiple components are used, then movement detection capability is provided, but device footprint increases
Solution Approach 1:
The patent merges the light emitter and light detector into a single integrated sensor module. The light emitter projects coherent light that reflects off the user's finger and returns to the same module's detector, eliminating the need for separate emitter and detector components and their associated collimation optics, thereby significantly reducing the sensor module footprint.
Solution Approach 2:
The integrated sensor module performs multiple functions: it emits light, detects reflected light, and processes interference signals to determine finger movement. This multi-functionality in a single compact module reduces the overall footprint compared to traditional multi-component optoelectronic systems.
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 compact, cost-effective sensor module that accurately detects movements for controlling electronic devices, offering additional functionalities and reducing mechanical wear and water/dust risks.
Implementation Method 1
self-mixing, or back-injection, interference, in which at least a part of the emitted light is reflected off a target outside the module, e.g. a user's finger, back into a cavity of the light emitter causing a modulation in frequency of the emitted optical beam
Implementation Method 2
The light emitter for enabling self-mixing interference, comprises a cavity resonator, into which at least a fraction of the light emitted by the light emitter is reflected, or backscattered, from an object outside the module
Data Source
AI summary
A self-mixing interferometry sensor module includes a light emitter and an electronic control unit coupled to the light emitter. The light emitter is configured to emit coherent electromagnetic radiation out of the sensor module. The light emitter is also configured to undergo self-mixing interference (SMI) caused by reflections of the emitted electromagnetic radiation from an object outside the sensor module. The electronic control unit is configured to detect a change in an electrical property of the light emitter caused by the SMI. The electronic control unit is also configured to determine from the detected change a movement of the object outside the sensor module. The electronic control unit is further configured to generate an output signal that includes information of the determined movement.