Waveguide Touch System Using Optical Interference
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Solution Overview
Problem
Current touch-sensing technologies for displays and devices lack sensitivity and accuracy in detecting touch events and determining their locations, particularly in alternative optics-based approaches beyond light-scattering and light-attenuation methods.
Innovation Solution
A touch system employing optical interference effects using first and second waveguides with optical paths that change upon a touch event, forming interfered light to detect and process the occurrence and location of touch events, with a network of waveguide-based interferometers providing touch-sensing capability over an area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If light-scattering and light-attenuation methods are used for touch sensing, then touch functionality can be enabled, but sensitivity and accuracy in detecting touch events and determining their locations are insufficient
Solution Approach 1:
The patent replaces conventional light-scattering and light-attenuation methods with optical interference effects. By using waveguides that deform under touch to create measurable optical path differences, the system achieves superior sensitivity and accuracy in detecting touch events and their locations, directly resolving the contradiction between measurement precision and reliability.
Solution Approach 2:
The patent changes the measurement parameter from light intensity (scattering/attenuation) to optical path difference through interference. This parameter transformation enables the system to detect sub-wavelength deformations of the waveguide, dramatically improving both the sensitivity and accuracy of touch event detection compared to conventional methods.
2Measurement precision
If waveguide deformation is used to detect touch events through optical interference, then sensitivity and accuracy are enhanced, but device complexity increases due to the network of waveguide-based interferometers
Solution Approach 1:
The patent divides the touch sensing area into a grid of independent waveguide-based interferometer units. Each unit locally detects touch events through waveguide deformation, and the collective array provides comprehensive coverage. This segmentation approach enables high precision detection while managing complexity through modular, repeatable units that can be systematically arranged.
Solution Approach 2:
The waveguide structures serve multiple functions: they guide light through the interferometer path, deform in response to touch events to create optical path differences, and collectively form the detection grid. This multi-functionality reduces the need for separate components, thereby managing device complexity while maintaining enhanced measurement precision.
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 precise detection of touch events and their locations, as well as the amount of force applied, through the use of optical fibers and unbalanced Mach-Zehnder interferometers, enhancing sensitivity and accuracy in touch-sensitive systems like keyboards.
Implementation Method 1
The change in the optical path difference ('optical path change') is detected by combining the light traveling in the two waveguides to form interfered light
Implementation Method 2
a touch event deforms at least one of the waveguides in a manner that causes the optical path difference to change
Data Source
Figure 1
Figure 2A~2B
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AI summary
A touch system that employs interference effects is disclosed. The touch system includes first and second waveguides that have first and second optical paths that define an optical path difference. The first and second waveguides are configured so that a touch event deforms at least one of the waveguides in a manner that causes the optical path difference to change. The change in the optical path difference is detected by combining the light traveling in the two waveguides to form interfered light. The interfered light is processed to determine the occurrence of a touch event. The time-evolution of the deformation at the touch-event location can also be determined by measuring the interfered light over the duration of the touch event.