Optical Touch Coupling With Edge Diffusers for Robust Light Sensing
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Solution Overview
Problem
Existing touch-sensitive panels face issues with signal loss, complexity, alignment challenges, and reduced robustness due to the use of collimated light and edge components, which increase cost and reduce compactness.
Innovation Solution
A touch-sensitive apparatus with a diffusive light scattering element arranged outside the panel sides, allowing diffusive light propagation above the touch surface, minimizing signal loss and alignment complexity, and enhancing robustness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If collimated light and edge components are used, then light propagation is achieved, but alignment complexity and manufacturing difficulty increase
Solution Approach 1:
The patent changes the light propagation parameter from collimated to diffusive scattering, which fundamentally alters how light travels through the panel. This parameter change eliminates the need for precise alignment between emitters, detectors, and optical components, while still achieving reliable light propagation for touch sensing.
Solution Approach 2:
The patent extracts and eliminates complex optical components such as lenses and reflectors from the system. By using diffusive light scattering at the panel edges, the invention removes the need for these additional components, thereby reducing alignment complexity and manufacturing difficulty while maintaining functional reliability.
2Illumination intensity
If diffuser overlays panel edges, then light scattering is achieved, but available touch surface area is reduced
Solution Approach 1:
The patent moves the diffusive light scattering function from the panel surface (2D) to the panel edges (1D boundary). By applying the diffuser material to the vertical edges rather than overlaying the horizontal surface, the invention achieves light scattering without encroaching on the touch surface area, effectively utilizing a different spatial dimension.
3Ease of operation
If multiple electro-optical components are used, then light control is improved, but system cost increases
Solution Approach 1:
The patent extracts and removes multiple electro-optical components including lenses, reflectors, and complex optical assemblies. By relying on the inherent diffusive scattering properties of the panel edges, the invention achieves adequate light control with minimal components, thereby reducing system cost while maintaining operational effectiveness.
4Reliability
If components are added on top of light transmissive panel, then light propagation is enhanced, but system robustness is compromised
Solution Approach 1:
The patent relocates the light propagation enhancement function from the panel surface to the panel edges. By applying diffusive material to the vertical edges rather than adding components on top of the horizontal surface, the invention enhances light propagation without compromising structural robustness or creating thermal expansion mismatches.
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 more reliable, compact, and cost-effective touch-sensitive apparatus with improved signal-to-noise ratio and scalability for various sizes, facilitating easier manufacturing and reduced component alignment requirements.
Implementation Method 1
a light guide arranged along the perimeter and having a first reflective surface comprising a diffusive light scattering element. The light emitters are arranged to emit a respective beam of light onto the diffusive light scattering element so as to generate propagating light that diffusively propagates above the touch surface
Implementation Method 2
the light detectors are arranged to receive detection light generated as said propagating light impinges on the diffusive light scattering element
Data Source
AI summary
A touch sensing apparatus is disclosed, comprising a light transmissive panel that defines a touch surface, an opposite rear surface, and panel sides extending between the touch surface and rear surface. The panel sides define a perimeter of the light transmissive panel. The touch sensing apparatus comprises a plurality of light emitters and detectors arranged along the perimeter and adjacent the panel sides, a light guide arranged along the perimeter and having a first reflective surface comprising a diffusive light scattering element. The light emitters are arranged to emit a respective beam of light onto the diffusive light scattering element so as to generate propagating light that diffusively propagates above the touch surface, wherein the light detectors are arranged to receive detection light generated as said propagating light impinges on the diffusive light scattering element, and wherein the diffusive light scattering element is arranged at least partly outside the panel sides and extending at least partly above the touch surface.