Optical Waveguide Touch Sensor for Display Devices
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Solution Overview
Problem
Current touch sensors for display devices face challenges in accurately detecting touch positions and estimating applied forces without generating noise or parasitic capacitance, which can affect touch sensitivity and image quality.
Innovation Solution
A touch sensor design featuring a plurality of first and second optical waveguides arranged in a stripe form, with cores made of elastomer and clad structures that allow for precise light transmission and detection, enabling accurate touch position specification and force estimation without electrical interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electrical touch sensors are used to detect touch positions and forces, then touch sensitivity can be achieved, but noise and parasitic capacitance are generated that affect image quality
Solution Approach 1:
The patent replaces electrical sensing mechanisms with an optical system. Light-emitting units send light through waveguides to light-receiving units, and touch detection is achieved by measuring changes in light transmission when the elastomer core deforms, rather than using electrical fields or capacitive sensing that generate noise and parasitic capacitance.
Solution Approach 2:
The elastomer core acts as an optical intermediary between the light-emitting and light-receiving units. When touched, the elastomer deforms and modulates the light path, converting mechanical touch force into optical signal changes that can be detected without direct electrical contact, thereby avoiding parasitic capacitance issues.
2Reliability
If waveguides with elastomer cores are used for optical transmission, then touch sensitivity is maintained, but structural complexity increases compared to conventional sensors
Solution Approach 1:
The elastomer core serves multiple functions simultaneously: it acts as the structural framework of the waveguide, provides the optical transmission medium, and functions as the touch-sensitive element that deforms under applied force. This multi-functionality reduces the need for separate components and simplifies the overall structure despite the sophisticated optical path design.
Solution Approach 2:
The use of elastomer material for the waveguide core enables flexibility and deformability while maintaining structural integrity. The elastomeric nature allows the waveguide to bend and deform in response to touch, providing tactile sensitivity without requiring complex mechanical structures or moving parts.
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 effectively specifies touch positions and estimates applied forces with high accuracy, maintaining high touch sensitivity and image quality by using elastomer cores and clad structures that deform to block or narrow optical paths, thus reducing noise and parasitic capacitance.
Implementation Method 1
cores made of elastomer and clad structures that allow for precise light transmission and detection, enabling accurate touch position specification and force estimation without electrical interference
Implementation Method 2
Each of the plurality of first optical waveguides and the plurality of second optical waveguides has a core including an elastomer
Implementation Method 3
a clad in contact with the core other than side surfaces of the core perpendicular to a longitudinal direction of the core at least in the display region; and a reflection surface at an interface between the core and the clad
Data Source
AI summary
Disclosed is a touch sensor including a plurality of first optical waveguides arranged in a stripe form, a plurality of second optical waveguides located over the plurality of first optical waveguides, arranged in a stripe form, and intersecting the plurality of first optical waveguides, and an intermediate layer between the plurality of first optical waveguides and the plurality of second optical waveguides. Each of the plurality of first optical waveguides and the plurality of second optical waveguides includes a core including an elastomer as well as a clad in contact with the core other than side surfaces of the core perpendicular to a longitudinal direction of the core. The intermediate layer has a modulus of elasticity higher than that of the elastomer.