Piezoelectric Push Button Circuit for Unipolar Signal Processing
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Solution Overview
Problem
Existing push button switches with piezoelectric elements face challenges in processing measurement signals effectively due to the generation of both positive and negative voltages, which complicates signal processing and evaluation.
Innovation Solution
Incorporating an amplifier circuit connected to the piezoelectric element's electrodes and an additional voltage source with an operating voltage greater than the maximum voltage between the electrodes, ensuring only positive voltages are generated at the circuit's output, facilitating easier signal processing. This setup includes a controller with A/D input connections and an analog multiplexer circuit for handling multiple switches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a piezoelectric element is used to generate measurement signals, then mechanical wear is eliminated and the design becomes more robust, but the generated voltage includes both positive and negative values which complicates signal processing
Solution Approach 1:
An additional voltage source is introduced as an intermediary element connected between one electrode of the piezoelectric element and the reference point of the amplifier circuit. This intermediary voltage source shifts the entire voltage range to positive values, eliminating the complexity of processing bipolar signals while preserving the measurement information.
Solution Approach 2:
The voltage parameter of the measurement signal is transformed by adding a DC offset from the additional voltage source. This parameter change converts the bipolar voltage signal into a unipolar signal, making it compatible with standard unipolar amplifier circuits and simplifying subsequent signal processing.
2Ease of operation
If the operating voltage of the additional voltage source is set appropriately, then the quiescent level is centered in the dynamic range improving signal processing, but the circuit requires more components
Solution Approach 1:
The operating voltage of the additional voltage source is specifically set to approximately half the operating voltage of the amplifier circuit. This parameter selection centers the quiescent level in the dynamic range of the amplifier, optimizing the utilization of the available voltage range and improving the linearity of signal processing.
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 simplifies the processing and evaluation of measurement signals by maintaining a positive voltage level at the output, enhancing the usability of the push button switch in electronic domestic appliances by reducing complexity and improving signal handling.
Implementation Method 1
a piezoelectric element arranged between a first electrode and a second electrode such that, when a pressure is exerted on the piezoelectric element, an electrical voltage is generated between the first and second electrodes
Data Source
AI summary
A push button switch including a piezoelectric element (10) which is arranged between a first electrode (16) and a second electrode (18) in such a manner that, when a pressure is exerted on the piezoelectric element, an electric voltage is generated between the first and the second electrode (16, 18). The voltage generated between the first and the second electrode (16, 18) of the piezoelectric element (10) is amplified via a suitable amplifier circuit (20) and supplied, for example, to a controller of an operating device of an electronic domestic appliance.