Optical Touch Surface with Tactile Features for Friction and Reflection Control
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Solution Overview
Problem
Touch-sensitive displays face issues with excessive friction due to user interactions and environmental light reflections, which negatively impact the user experience.
Innovation Solution
An optical touch-sensitive device with a planar optical waveguide structure featuring tactile surface features and emitters/detectors that reduce friction and minimize light reflections by using a tactile coating and anti-reflective layers, allowing for effective detection of touch events through total internal reflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a smooth touch-sensitive surface is used, then light reflections are minimized, but friction between the touch object and surface becomes excessive
Solution Approach 1:
The patent applies different surface properties to different regions or aspects of the touch surface. The base surface maintains optical smoothness for minimal reflection, while tactile features (protrusions, recesses, or textured patterns) are introduced in specific locations to reduce friction. This allows the surface to have locally differentiated properties: optically smooth for light interaction and tactilely textured for friction reduction.
Solution Approach 2:
The patent uses composite surface structures combining materials or surface treatments with different properties. One layer or region provides optical smoothness to minimize reflections, while another layer or region provides tactile texture to reduce friction. The composite structure integrates both functions: the smooth portion handles light interaction while the textured portion handles tactile interaction.
2Ease of operation
If tactile surface features are added to reduce friction, then user tactile experience improves, but light reflections increase
Solution Approach 1:
The tactile features are designed with specific geometric characteristics (size, shape, spacing, depth) that are locally optimized to minimize their optical impact while maximizing their tactile effect. The features are small enough or shaped in such a way that they do not significantly disrupt the overall optical smoothness of the surface, thus minimizing light reflections while still providing friction reduction.
Solution Approach 2:
The patent optimizes parameters of the tactile features (such as protrusion height, recess depth, feature spacing, and surface area ratio) to find a balance point where tactile friction reduction is achieved while optical reflection remains minimized. By carefully controlling these parameters, the surface maintains its optical properties while gaining tactile benefits.
3Object-affected harmful factors
If anti-reflective layers are applied to minimize light reflections, then environmental light interference reduces, but surface tactile properties deteriorate
Solution Approach 1:
The anti-reflective treatment is segmented or patterned rather than applied uniformly across the entire surface. The anti-reflective layer is applied in specific regions or as a discontinuous pattern that allows tactile features to protrude through or be exposed in certain areas. This segmentation enables the surface to have anti-reflective properties in some regions while maintaining tactile friction reduction in other regions.
Solution Approach 2:
The solution moves the tactile features to a different dimensional level by making them protrude through the anti-reflective layer. The tactile features extend in the vertical dimension beyond the anti-reflective coating, allowing them to provide friction reduction while the anti-reflective layer covers the base surface to minimize reflections. This dimensional separation allows both functions to coexist without compromising each other.
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 enhances the tactile experience and reduces the impact of environmental light reflections, providing improved user interaction and sensitivity while maintaining efficient touch event detection.
Implementation Method 1
The emitters produce optical beams that propagate through the waveguide structure via total internal reflection (TIR) to the detectors
Data Source
AI summary
An optical touch-sensitive device includes a touch-sensitive surface over which touch events are detectable. The device also includes surface features on the surface that reduce touch object friction relative to an absence of surface features. Emitter and detectors are arranged along a periphery of the touch-sensitive surface. The emitters can produce optical beams that travel across the touch-sensitive surface to the detectors. Touches on the touch-sensitive surface disturb the optical beams and the touch-sensitive device determines touch events based on the disturbed optical beams. The surface features may also be arranged to reduce glare by diffusing light. In some embodiments, an anti-reflective layer is on top of the touch-sensitive surface and the surface features.