Acoustic Touch Sensor with Capacitive Hold Detection
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Solution Overview
Problem
Existing touch-sensing devices based on acoustic signals struggle to accurately detect prolonged touch hold actions and release events, as the fading acoustic signal limits their ability to differentiate between touch-release and touch-hold actions.
Innovation Solution
Integration of a capacitive sensor using an elastically compressive and dielectric acoustic isolator with conductive electrodes on either side, which monitors capacitance changes to determine the duration of touch events, allowing differentiation between short and long touch events and detecting release actions even after the acoustic signal has faded.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If acoustic signal detection is used for touch position determination, then touch location accuracy is improved, but the ability to detect prolonged touch hold actions deteriorates
Solution Approach 1:
The patent combines acoustic signal detection with capacitive sensing into a hybrid touch detection system. The acoustic transducers detect touch position through acoustic waves, while the capacitive sensor (formed by the acoustic isolator and electrodes) simultaneously monitors capacitance changes to detect both touch position and touch duration. This merging allows the system to maintain high position accuracy while adding the capability to detect prolonged touch hold actions that acoustic signals alone cannot detect.
Solution Approach 2:
The acoustic isolator serves multiple functions: it provides acoustic decoupling between the interaction means and the support structure, and simultaneously acts as a dielectric element in a capacitive sensor. This multi-functionality allows the same component to enable both acoustic touch detection and capacitive touch duration monitoring, resolving the contradiction between position accuracy and hold detection capability.
2Measurement precision
If acoustic signal analysis is used for touch detection, then touch position determination is improved, but the detection of release actions deteriorates
Solution Approach 1:
The capacitive sensor provides continuous feedback on the force applied to the interaction means by monitoring capacitance changes over time. This feedback mechanism allows the system to detect not only the presence of a touch but also the duration and release of the touch. When the user releases the touch, the capacitance returns to its baseline value, providing clear feedback that a release action has occurred, thereby preventing loss of release information.
3Reliability
If acoustic isolator is provided for acoustic decoupling, then acoustic signal detection is improved, but the device complexity increases
Solution Approach 1:
The acoustic isolator is designed to perform dual functions: acoustic decoupling and capacitive sensing. By making the acoustic isolator itself the dielectric element of the capacitive sensor, the patent eliminates the need for separate sensor components. The same physical structure (acoustic isolator with electrodes on either side) enables both acoustic isolation and capacitive touch detection, thereby reducing overall device complexity while maintaining acoustic signal detection reliability.
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
Enables precise classification of touch events into short or long actions and accurate detection of release moments, enhancing the capability to distinguish between touch-hold and touch-release actions, improving the accuracy of touch event classification beyond the limitations of acoustic signal detection.
Implementation Method 1
an acoustic isolating means (11) being elastically compressive and dielectric provided on one surface of the interaction surface (3)
Implementation Method 2
a first conductive electrode (13) provided between the interaction surface and the isolating means, a second conductive electrode (15), the first conductive electrode (13) and the second conductive electrode (15) sandwiching the isolating means (11)
Data Source
AI summary
The invention relates to a touch-sensing device comprising an interaction surface with a touch location system for determining a touch position based on an acoustic signal. Gaskets, forming a means for acoustically isolating the interaction surface from the underground on which it is placed, are provided with an upper electrode and a lower electrode. The gaskets are elastically compressible and have dielectric properties, so that the two electrodes and the gasket form a capacitor with a capacitance that varies with the force applied to the interaction surface. In addition to the touch position determined by the acoustic signal, the touch-sensing device detects a touch duration based on capacitance variations, so that touch events can be classified according to their duration. The invention also relates to the corresponding method.