Optical Waveguide Touch Screen Panel for Gloved Input
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Solution Overview
Problem
Existing touch screen technologies face issues such as low light transmittance, high cost, and malfunction due to contamination or use with gloved fingers or stylus pens, particularly in resistive, capacitive, infrared, and surface acoustic wave types.
Innovation Solution
A touch screen panel utilizing an optical grid with optical waveguides, comprising a core and clad with specific refractive indices, where the core has a higher refractive index than the clad, and an optical source and receivers to detect changes in light intensity upon touch or pressure application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If resistive type touch screen uses two substrates with transparent electrodes, then touch detection function is achieved, but light transmittance is low and battery efficiency decreases
Solution Approach 1:
The patent replaces the resistive mechanical contact system with an optical sensing system. Instead of using two substrates that must physically contact through pressure, the invention uses optical waveguides that detect touch through changes in light propagation characteristics, eliminating the need for additional power-consuming components while maintaining touch detection functionality
Solution Approach 2:
The patent changes the detection parameter from electrical contact resistance to optical properties (light intensity, refraction, reflection). By measuring changes in light parameters when the touch occurs, the system achieves touch detection without the power consumption issues of resistive screens
2Reliability
If capacitive type touch screen senses static electricity, then touch detection is achieved, but cost is high and it does not work with gloved finger or stylus pen
Solution Approach 1:
The optical waveguide-based touch detection system is designed to detect various types of touch inputs universally. It can detect touches from fingers, gloved fingers, stylus pens, and other objects by sensing changes in light propagation, making the system compatible with multiple input methods unlike capacitive screens that only work with bare fingers
3Measurement precision
If IR type touch screen uses infrared rays, then touched portion detection is achieved, but contaminated surface causes malfunction and additional lens component is required
Solution Approach 1:
The patent introduces optical waveguides as intermediary elements between the light source and the detection point. These waveguides guide light along specific paths and detect touch through changes in light propagation within the waveguide structure, making the detection system less sensitive to surface contamination compared to direct infrared beam methods that require clear optical paths
4Measurement precision
If optical waveguide touches or pressure is applied, then touched position and pressure can be detected, but optical loss occurs
Solution Approach 1:
The system uses feedback from light intensity changes in the optical waveguide to detect touch position and pressure. By monitoring how touch affects light propagation and using this feedback information, the system achieves precise detection while minimizing the actual optical energy loss through efficient light collection and detection mechanisms
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 solution allows for precise detection of touched positions and pressure with minimized error, improving light transmittance and functionality, including operation with gloved fingers or stylus pens, while reducing optical loss and maintaining high spatial resolution.
Implementation Method 1
a core including a plurality of horizontal and vertical lines provided in a grid shape, wherein the core has a first refractive index, and an upper surface of the core is exposed to the atmosphere; an intermediate clad formed between each of gaps included in the core, wherein the intermediate clad has a second refractive index which is lower than the first refractive index
Data Source
AI summary
A touch screen panel is disclosed, which is capable of sensing an exact position touched by a user or instrument, or a pressured applied to the touched position, wherein the touch screen panel comprises a core including a plurality of horizontal and vertical lines provided in a grid shape, wherein the core has a first refractive index, and an upper surface of the core is exposed to the atmosphere; an intermediate clad formed between each of gaps included in the core, wherein the intermediate clad has a second refractive index which is lower than the first refractive index, and a height of the intermediate clad is identical to a height of the core; an optical source configured to apply an optical signal to an input end of each of the plurality of horizontal and vertical lines; and a plurality of receivers configured to sense an intensity of the optical signal passing through an output end of each of the plurality of horizontal and vertical lines, the optical signal applied by the optical source.