Piezoelectric Transducer Waveform Control for Tactile Feedback
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Solution Overview
Problem
Touchscreen systems lack the ability to provide tactile feedback that mimics mechanical inputs, such as pressing a dome button, due to their inability to embed mechanical buttons, resulting in an unsatisfying user experience.
Innovation Solution
A system using a deformable material, such as a piezoelectric transducer, is mounted under the touchscreen to emulate the motion of a pushbutton, with dynamically adjusted excitation signals to ensure the tactile feedback is felt without generating audible artifacts, utilizing a fly-back boost converter with a feedback loop to control the energy transfer and waveform generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a piezoelectric transducer is used to provide tactile feedback on a touchscreen, then the user experience is improved by simulating mechanical button press sensation, but audible clicks or artifacts may be generated
Solution Approach 1:
The patent applies dynamics by making the excitation waveform adaptive and dynamically adjustable. The system modifies the waveform parameters (amplitude, frequency, duration) in real-time based on feedback from sensors that detect transducer position and velocity, thereby optimizing the tactile sensation while minimizing audible artifacts during different phases of button press simulation.
Solution Approach 2:
The patent implements feedback by using sensors to monitor the transducer's position and velocity during actuation, and using this information to dynamically adjust the excitation waveform. This closed-loop control ensures that the tactile feedback remains realistic while preventing the generation of audible clicks by adjusting the waveform to match the actual transducer motion characteristics.
2Use of energy by moving object
If a boost converter is used to generate excitation waveforms for the piezoelectric transducer, then energy efficiency is improved, but the system complexity increases
Solution Approach 1:
The patent applies universality by designing the boost converter to perform multiple functions: it not only steps up the voltage to the required level for the piezoelectric transducer but also generates the excitation waveform itself and provides the feedback control mechanism. This multi-functional approach consolidates what could be separate components into a single integrated system, reducing overall complexity while maintaining energy efficiency.
Solution Approach 2:
The patent applies parameter changes by using the boost converter's duty cycle and switching frequency as controllable parameters to dynamically adjust the excitation waveform characteristics. By modifying these electrical parameters, the system can optimize both the tactile feedback quality and energy efficiency without requiring additional dedicated waveform generation circuitry.
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 system effectively provides tactile feedback that simulates the sensation of pressing a button, eliminating audible clicks and ensuring a satisfying user experience while being energy-efficient and adaptable to varying loads.
Implementation Method 1
A user selecting an icon on a touchscreen surface may feel a vibration... uses a deformable material, such as a piezoelectric transducer, is mounted under the touchscreen to emulate the motion of a pushbutton
Implementation Method 2
utilizing a fly-back boost converter with a feedback loop to control the energy transfer and waveform generation
Data Source
AI summary
Transducers formed as part of a touchscreen system emulate the motion of a pushbutton or other mechanical elements. A touchscreen system positions a transducer adjacent to an icon displayed on the touchscreen surface. When a user touches the icon, the transducer senses the touch and is then deformed in a pattern that emulates a mechanical motion, giving the user the sensation of touching a mechanical button. An excitation signal applied to the transducer is compared to a target excitation signal that, when applied to the transducer, causes the transducer to emulate the desired motion. When any differences between the two signals are detected, the excitation signal is adjusted so that the motion is corrected. The target excitation signal, or time and voltage segments defining it, are stored in memory and retrieved for comparison. The excitation signal is also selected to reduce any acoustic artifacts that can cause the transducer to generate audible clicks.