Acoustic Touch Substrate with Dual-Surface Multi-Touch Sensing
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Solution Overview
Problem
Acoustic touch sensors face difficulties in accurately distinguishing and determining the coordinates of multiple simultaneous touches due to insufficient clear coordinate information, leading to ambiguity and erroneous touch position detection.
Innovation Solution
The implementation of a substrate with opposite surfaces that propagate surface acoustic waves, featuring a transmitting element and a receiving element on each surface, which alternate in transmitting and receiving waves to differentiate between touches by analyzing signal perturbations and attenuations, forming probable zones of touch contact to distinguish between simultaneous touches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional acoustic touch sensors use single-surface wave propagation, then the device structure is simple, but the ability to distinguish multiple simultaneous touches is insufficient
Solution Approach 1:
The patent transitions from single-surface acoustic wave propagation to dual-surface oscillating propagation, adding a vertical dimension (top-bottom surfaces) to the wave propagation path. This creates alternating sensitive zones that enable distinction between multiple simultaneous touches by analyzing which surface the wave is propagating on, thereby improving measurement precision without excessive complexity increase
Solution Approach 2:
The touch detection area is segmented into alternating sensitive zones corresponding to different propagation surfaces (top and bottom). Each surface creates distinct zones where touches can be differentiated, allowing the system to resolve multiple simultaneous touches by determining which surface each touch occurred on
2Measurement precision
If acoustic touch sensors increase the number of transducers per coordinate axis to improve multi-touch detection, then touch detection accuracy improves, but the device complexity and cost increase
Solution Approach 1:
Each transducer pair (one transmitting, one receiving) serves multiple functions: it detects touches on both the top and bottom surfaces alternately, and contributes to forming multiple sensitive zones across the touch area. This multi-functionality allows dual-surface oscillating propagation to achieve multi-touch detection capability without increasing the number of transducers per coordinate axis
Solution Approach 2:
The acoustic waves oscillate periodically between the top and bottom surfaces, creating alternating sensitive zones. This periodic action allows the same transducer pair to sequentially detect touches on different surfaces, enabling multi-touch distinction without requiring additional transducers for each surface
3Adaptability or versatility
If the substrate thickness is increased to allow surface acoustic wave propagation between opposite surfaces, then multi-touch differentiation capability improves, but the manufacturing precision requirements and material usage increase
Solution Approach 1:
The patent utilizes the parameter of substrate thickness to enable a specific physical phenomenon (surface acoustic wave oscillation between surfaces). By controlling the thickness to support this oscillation mode, the system achieves multi-touch differentiation capability. The thickness parameter is optimized to balance the need for wave propagation between surfaces with manufacturing feasibility
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 approach enables accurate determination of positional information for multiple simultaneous touches, reducing ambiguity and improving touch detection accuracy by varying touch sensitivity along the acoustic path and utilizing top-bottom oscillation phenomena to create sensitivity grids for precise coordinate identification.
Implementation Method 1
a substrate that has two opposite surfaces and that is adapted to propagate surface acoustic waves along each opposite surface
Implementation Method 2
said substrate being adapted to transfer, through the substrate, surface acoustic waves between the opposite surfaces so as to alternate in the touch region the propagating surface acoustic waves from each opposite surface
Implementation Method 3
The transmitting element may comprise an acoustic transducer that generates propagating surface acoustic waves
Implementation Method 4
a reflector array that reflects the generated propagating surface acoustic waves onto each opposite surface
Implementation Method 5
touching the substrate surface at a point causes a loss of energy by the surface acoustic waves passing through the point of touch. This is manifested as an attenuation of the surface acoustic waves
Implementation Method 6
Detection circuitry associated with each receiving transducer detects the attenuation as a perturbation in the surface acoustic wave signal
Data Source
AI summary
An acoustic touch apparatus (100) that utilizes the transfer of surface acoustic waves from one surface (115), through the touch substrate (105), to another surface (110) and a grid of sensitivity zones (Z) formed on one of the surfaces (115) to enable multi-touch capabilities.