Piezo-Electric Transducer Sensing Circuit Segmentation
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Solution Overview
Problem
Conventional piezo-electric transducer systems face limitations in accuracy due to parasitic effects when combining drive and sensing functionalities in the same circuit, leading to inadequate sensing performance, especially with negative voltages and multi-channel configurations.
Innovation Solution
A driver circuit design that includes a sense/drive algorithm and a sensing switch to accurately sense voltages across piezo-electric transducers by repeatedly zeroing the output voltage and segmenting voltage measurements, overcoming parasitic conduction paths and enabling accurate force detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the driver circuit and sensing circuit are combined in the same circuit, then device complexity is reduced, but measurement precision deteriorates due to parasitic effects from interconnection of power devices
Solution Approach 1:
The patent segments the voltage measurement process into multiple discrete steps, measuring different voltage portions sequentially through controlled switching of power devices. This temporal segmentation allows the system to measure the complete voltage across the piezo-electric transducer while avoiding simultaneous parasitic conduction paths, thereby maintaining measurement precision without requiring separate driver and sensing circuits.
2Device complexity
If conventional sensing methods are used with piezo-electric transducers, then device simplicity is maintained, but measurement precision deteriorates especially with negative voltages and multi-channel configurations
Solution Approach 1:
The patent applies preliminary action by pre-charging or pre-discharging capacitors to known voltage states before performing measurements. This preparatory step establishes a controlled initial condition that eliminates uncertainty from residual charges, enabling accurate measurement of both positive and negative voltage excursions across the piezo-electric transducer while using a single integrated circuit.
Solution Approach 2:
The patent implements feedback by continuously monitoring the voltage across the piezo-electric transducer and using this information to control the switching sequence of power devices. The measured voltage feedback determines when to switch between different measurement configurations, allowing the system to adaptively handle both drive and sense operations with high precision in a unified circuit architecture.
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 enhances sensing accuracy by reconstructing total sensed voltage values from segmented measurements, effectively addressing limitations in conventional systems and enabling precise force detection across piezo-electric transducers, including negative voltages and multi-channel configurations.
Implementation Method 1
In conventional haptic feedback systems, which use the piezo-electric effect, a driver circuit applies a high-voltage signal to the piezo-electric transducer, and in response to the applied high-voltage signal, the piezo-electric transducer generates a mechanical movement sufficient to give a haptic sensation to a user
Implementation Method 2
when a force is applied to the piezo-electric transducer by the user, a sensing circuit generates a sensed voltage signal
Data Source
Figure 1
Figure 2A~2B
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AI summary
In a driver for a piezo-electric transducer, when a converter circuit and a sensing circuit are the same circuit, many limitations exist on the accuracy of the sensing, due to multiple parasitic effects arising from the interconnection of the power devices. These limitations may limit viability of the sensing for many applications, in particular an accurate determination of when the force on the piezo-electric transducer is fully removed. Providing an additional switch in the sensing circuit configured to repeatedly zero the sensed voltage across the piezo-electric transducer each time the sensed voltage reaches a threshold voltage generates a plurality of voltage segments between zero and the threshold voltage. Accordingly, a controller may then be configured to generate a digital reconstruction of the sensed voltage across the piezo-electric transducer by adding the plurality of voltage segments.