Acoustic Touch Sensing With Dual-Frequency False Wake-Up Filtering
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional acoustic touch devices face difficulties in distinguishing between a finger touch and other factors like water or oil due to interference in electrical signals, leading to increased power consumption and false wake-ups.
Innovation Solution
The acoustic touch device employs a dual-signal capture system with a controller that differentiates between low-frequency signals from piezoelectric deformation and high-frequency signals from ultrasonic waves, using threshold values and duration analysis to distinguish between valid finger touches and interference from water or oil.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional acoustic touch devices use a single high-frequency acoustic wave signal for touch detection, then the device can detect finger touches through acoustic wave reflection, but the device cannot distinguish between finger touches and interference from water or oil, leading to false wake-ups and increased power consumption
Solution Approach 1:
The patent divides the touch detection process into two distinct signal frequency segments: low-frequency signals (first frequency range) for detecting finger touches through piezoelectric deformation, and high-frequency signals (second frequency range) for detecting interference from water or oil through acoustic wave reflection. By segmenting the detection frequencies, the system can distinguish between different types of touches and reduce false wake-ups.
Solution Approach 2:
The patent implements periodic signal transmission by alternately sending low-frequency and high-frequency acoustic waves through the ultrasonic transmitting unit. The controller periodically switches between different frequency ranges to collect both types of signals, enabling continuous monitoring and differentiation between finger touches and interference through rhythmic signal analysis.
2Ease of operation
If the acoustic touch device continuously monitors electrical signals to detect touches, then the device can respond to user input, but the device consumes excessive power due to frequent false wake-ups caused by interference signals
Solution Approach 1:
The patent employs feedback mechanisms where the controller analyzes both low-frequency and high-frequency signals and makes wake-up decisions based on combined information. The system provides feedback to the power supply circuit about the nature of detected signals, enabling intelligent power management that wakes the device only when genuine finger touches are confirmed, thereby reducing unnecessary power consumption.
3Device complexity
If the acoustic touch device uses a single frequency range for signal detection, then the device structure remains simple, but the device lacks the capability to differentiate between various types of touches and environmental interference
Solution Approach 1:
The patent makes the ultrasonic transmitting unit and ultrasonic receiving unit multi-functional by enabling them to operate in two different frequency ranges. The same hardware components serve dual purposes: low-frequency operation for finger touch detection through piezoelectric effects, and high-frequency operation for interference detection through acoustic wave reflection, eliminating the need for separate dedicated hardware for each function.
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 effectively reduces false wake-ups and power consumption by accurately differentiating between finger touches and interference, ensuring reliable touch detection and reduced power usage.
Implementation Method 1
the piezoelectric sheet deforms, and the piezoelectric sheet generates an electrical signal indicating that the acoustic wave generator or the acoustic wave receiving element has been touched or impacted
Implementation Method 2
an acoustic wave generator of an acoustic touch device sends a high-frequency acoustic wave to a top surface of a cover. When a finger is touching the cover, a portion of the acoustic wave can be blocked by the finger, and a portion of the acoustic wave can be reflected and be received by an acoustic wave receiving element
Data Source
AI summary
An acoustic touch device able to distinguish between user finger touches and other noise-making events includes ultrasonic transmitting and receiving units, and a controller. The ultrasonic receiving unit generates low-frequency electrical signals when the acoustic touch device is touched by an external object or affected by acoustic noise. The low frequency electrical signals cause variation in the output electrical signals of the ultrasonic receiving unit. The controller is configured to power on or power off the ultrasonic transmitting unit according to such variation.