Touch Sensing System Distinguishing Digit and Liquid Events
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Solution Overview
Problem
Current technologies fail to effectively distinguish between different touch events, such as a digit versus a liquid droplet, and cannot accurately determine actual-touch events versus non-touch events using piezoelectric micromechanical ultrasonic transducers and force-measuring elements.
Innovation Solution
A force-measuring and touch-sensing system incorporating piezoelectric ultrasonic transducers and force-measuring elements, where ultrasound signals are transmitted and received to differentiate between touch events based on voltage signal processing, determining event types by analyzing the percentage decrease in digital data and noise threshold values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If piezoelectric ultrasonic transducers and force-measuring elements are used to detect touch events, then touch-sensing capability is improved, but the ability to distinguish between different types of touch events (digit vs. liquid droplet) deteriorates
Solution Approach 1:
The patent segments the touch detection function into two independent sensing channels: ultrasonic transducers for detecting touch presence and piezoelectric force-measuring elements for detecting applied force. By processing signals from both channels separately and comparing them, the system can distinguish between different event types (digit touch vs. liquid droplet) that would otherwise be indistinguishable using a single sensing method.
Solution Approach 2:
The patent introduces signal processing circuitry as an intermediary that receives and processes signals from both the ultrasonic transducers and piezoelectric force-measuring elements. This intermediary component analyzes the combined signal characteristics and determines event type based on predefined criteria, enabling differentiation between touch events that the raw sensors alone cannot distinguish.
2Loss of information
If voltage signal processing is used to determine event types, then event differentiation is improved, but system complexity increases
Solution Approach 1:
The patent changes the parameters being measured and compared: it evaluates the percentage decrease in ultrasonic signal strength alongside the magnitude of piezoelectric voltage signals, and compares these against predefined thresholds. By monitoring multiple parameters simultaneously (signal decrease percentage, voltage magnitude, threshold comparisons) and using logical combinations of these parameters, the system achieves event differentiation through relatively simple threshold-based logic rather than complex algorithms.
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 accurate differentiation between various touch events and actual-touch events, improving the reliability of touch-sensing systems by distinguishing between significant and non-significant forces applied to the sense region.
Implementation Method 1
Each PUT or PFE includes a piezoelectric capacitor. Each PUT transmitter transmits ultrasound signals towards the sense region
Implementation Method 2
a signal processing circuitry reads voltage signals from the PUT receivers generated in response to ultrasound signals arriving at the PUT receivers from the sense region
Implementation Method 3
The signal processing circuitry reads voltage signals from the PFEs generated in response to a low-frequency mechanical deformation of the respective piezoelectric capacitor
Data Source
AI summary
A method of distinguishing between a first-type touch event and a second-type touch event is disclosed. A force-measuring and touch-sensing system includes piezoelectric force-measuring elements (PFEs) and piezoelectric ultrasonic transducers (PUTs), wherein each PUT can be configured as a transmitter (PUT transmitter) and/or a receiver (PUT receiver). The force-measuring and touch-sensing system is configured at a sense region. Each PUT transmitter transmits ultrasound signals towards the sense region and voltage signals are generated at the PUT receivers in response to ultrasound signals arriving from the sense region. Voltage signals are generated at PFEs in response to a low-frequency mechanical deformation of the respective piezoelectric capacitors. An event is determined to be a first-type touch event or a second-type touch event depending on a PUT data decrease and a magnitude of PFE data.