Waveguide Interferometric Multi-Point Force Sensor
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Solution Overview
Problem
Existing touch and force detection systems for electronic devices require multiple sensors to detect inputs at multiple locations, which increases complexity and cost, while light-based sensors can only measure distance or displacement at a single location, limiting their multi-point detection capabilities.
Innovation Solution
The use of self-mixing interferometry with a single laser diode and an optical waveguide equipped with multiple light out-couplers allows for the detection of touch and force inputs at multiple locations by analyzing changes in the operational parameters of the laser light source, enabling precise location and magnitude determination through spectrum analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple light-based sensor mechanisms are used to detect inputs at multiple locations, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent combines multiple sensing functions into a single optical waveguide system. The waveguide integrates multiple light out-couplers at different positions, allowing one unified structure to perform multi-point detection that would otherwise require multiple separate sensors. This merging approach maintains measurement precision across multiple locations while eliminating the need for multiple independent sensor mechanisms.
Solution Approach 2:
The optical waveguide is designed as a universal structure that serves multiple sensing functions simultaneously. By positioning light out-couplers at different locations along the waveguide, a single device can detect inputs at multiple points, making the system multi-functional rather than requiring specialized sensors for each detection point.
2Device complexity
If a single laser light source is used, then device complexity is reduced, but measurement precision at multiple locations deteriorates
Solution Approach 1:
The optical waveguide acts as an intermediary that distributes light from a single laser source to multiple sensing locations. The waveguide receives light at one point and guides it through its structure to multiple out-couplers positioned at different locations, enabling the single light source to effectively reach and sense at multiple points with maintained precision.
Solution Approach 2:
The patent transitions from a point-based sensing approach to a distributed linear sensing approach by using the waveguide's spatial extension. Instead of multiple discrete light sources at different points, a single source feeds a linearly extended waveguide structure that distributes light along its length, adding a dimensional aspect to the sensing capability.
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 simplifies the detection of touch and force inputs across an electronic device's surface by using a single laser source and waveguide, enhancing precision and reducing the need for multiple sensors, thereby improving user interaction with electronic devices.
Implementation Method 1
a user input on the input surface at a first sensing location of the respective sensing locations changes an operational parameter of the laser light source that is detected by the processing electronics
Implementation Method 2
an optical waveguide positioned interior to the electronic device in proximity to the input surface, and a laser light source operable to insert light into the optical waveguide
Implementation Method 3
The optical waveguide comprises a full or partial reflector positioned at a first distance from the insertion location of the optical waveguide
Data Source
AI summary
Disclosed herein are structures, devices, and systems for detecting touch and force inputs at multiple sensing locations on a surface of an electronic device using waveguide-based interferometry. A laser light source, such as a VCSEL, inserts light into a waveguide positioned adjacent to the sensing locations, and an input at a sensing location alters the inserted light in the waveguide allowing for determination of the input's touch or force at the sensing location. Wavelength modulation of the inserted light allows isolation in frequency of the signals from each sensing location. Optical phase locking can be used to lock an absolute distance beat frequency corresponding to a stationary reference point in the waveguide.