Piezoelectric Touch Panel Knock Detection to Reduce False Triggers
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing touch detection systems, such as capacitance touch panels, face high costs and false triggers when used on large surfaces like washing machine or refrigerator doors, as they cannot distinguish touch force or material, and alternative solutions like microphones and acceleration sensors pose installation challenges and design issues.
Innovation Solution
A touch detection device utilizing a piezoelectric sensor mounted on a touch panel with a control circuit board to process detection signals, employing acoustic wave absorbing materials to isolate sound waves and determine correct human finger knock events based on threshold time differences and signal processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a capacitance touch panel is used for large surface touch detection, then the touch detection function is provided, but the cost becomes very high and false triggers occur due to inability to distinguish touch force and material
Solution Approach 1:
The patent replaces the capacitance touch panel with a piezoelectric sensor-based detection system. The piezoelectric sensor detects mechanical vibration signals generated by knocking or touching actions, converting mechanical energy to electrical signals. This substitution eliminates the need for expensive large-area capacitance panels while providing accurate touch detection through vibration signal analysis, thereby reducing manufacturing cost while maintaining detection accuracy.
2Measurement precision
If a microphone is used to detect sound signals, then touch detection function is provided, but the installation becomes very troublesome due to need for closed voice cavity
Solution Approach 1:
The patent replaces the microphone-based acoustic detection system with a piezoelectric sensor that directly detects mechanical vibrations. The piezoelectric sensor can be mounted directly on the touch surface without requiring enclosed acoustic cavities or complex acoustic path designs. This simplifies the device structure and installation process while maintaining the ability to detect touch-related sounds and vibrations.
3Measurement precision
If an acceleration sensor is used to detect vibration signals, then touch detection function is provided, but the circuit board cannot be hidden when the vibration surface is made of transparent material
Solution Approach 1:
The patent replaces the acceleration sensor mounted on the circuit board with a piezoelectric sensor that can be integrated directly into the touch surface structure. The piezoelectric sensor generates electrical signals directly from mechanical stress applied to the touch surface, eliminating the need for separate acceleration sensors and complex circuit board arrangements. This allows transparent touch surfaces to maintain their aesthetic appearance without visible electronic components.
4Measurement precision
If piezoelectric sensor is used to detect knock events, then the detection accuracy is improved, but the system complexity increases due to signal processing requirements
Solution Approach 1:
The patent analyzes specific parameters of the vibration signal to distinguish genuine knock events from other disturbances. By examining characteristics such as signal amplitude, frequency spectrum, time-domain features, and arrival time differences at multiple sensors, the system achieves accurate knock detection. This parameter-based analysis provides a systematic approach to signal processing that balances detection accuracy with computational complexity.
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 accurately identifies human finger knock events with low costs and simple configuration, reducing false triggers and design challenges, allowing for efficient and cost-effective implementation on various surfaces including glass, stainless steel, and wood.
Implementation Method 1
a piezoelectric sensor mounted on the touch panel and adapted to detect a knock or touching event applied to the touch panel
Implementation Method 2
employing acoustic wave absorbing materials to isolate sound waves
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
A touch detection device includes: a touch panel; a piezoelectric sensor mounted on the touch panel and adapted to detect a knock event applied to the touch panel; and a control circuit board electrically communicated with the piezoelectric sensor. The control circuit board includes: a signal processing circuit adapted to process a detection signal output from the piezoelectric sensor; and a controller adapted to determine whether the knock event is a correct human finger knock event based on the processed detection signal. The touch detection device may conveniently and accurately identify whether the knock event applied on the touch panel is the correct human finger knock event.