Piezo MEMS Driver Circuit with Intermediary Capacitor
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Solution Overview
Problem
Existing piezo driver technologies suffer from high power loss due to ineffective voltage conversion, leading to inefficient operation of piezoelectric MEMS sound transducers.
Innovation Solution
A method and circuit that gradually charge and discharge the piezo component using a recharging unit in a parallel circuit, allowing for step-by-step energy transfer between the energy store and the piezo component, reducing power loss by incrementally increasing voltage and enabling energy recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a voltage converter is used to transfer electrical charge between energy storage components and the piezo device, then the piezo driver can operate in various states, but the voltage converter operates ineffectively leading to high power loss
Solution Approach 1:
The patent introduces an intermediary capacitor as a mediator between the energy storage component and the piezo device. This intermediary stores electrical charge temporarily and releases it in controlled amounts, enabling versatile operating states while avoiding the high power loss associated with continuous voltage converter operation. The intermediary capacitor acts as a buffer that decouples the direct connection between energy storage and piezo actuation.
Solution Approach 2:
The patent implements periodic charging and discharging cycles of the intermediary capacitor. Instead of continuous voltage conversion, the system periodically transfers charge from the energy storage component to the intermediary capacitor, then releases it to the piezo device. This periodic action reduces average power loss while maintaining the ability to operate in various states through controlled timing and frequency of these cycles.
2Device complexity
If electrical energy is directly transferred from energy store to piezo component, then the circuit is simple, but power loss is high due to ineffective voltage conversion
Solution Approach 1:
The patent adds an intermediary capacitor to the direct energy transfer path. This intermediary component enables efficient voltage conversion by storing and releasing charge in discrete packets, reducing power loss without requiring complex continuous voltage conversion circuitry. The intermediary capacitor provides a simple yet effective solution that maintains circuit simplicity while dramatically improving energy efficiency.
3Power
If high voltage is applied to the piezo component, then the sound transducer performance improves, but heat dissipation and component stress increase
Solution Approach 1:
The patent uses periodic charging cycles where the intermediary capacitor is charged to high voltage and then discharged in controlled pulses to the piezo component. This periodic action delivers the necessary high voltage for optimal sound transducer performance only when needed, rather than maintaining continuous high voltage. The intervals between pulses allow heat to dissipate, reducing overall temperature and component stress while maintaining peak performance during active sound generation.
Solution Approach 2:
The patent segments the voltage delivery into discrete pulses rather than continuous high voltage application. The intermediary capacitor stores energy and releases it in segmented pulses to the piezo component, providing high voltage when needed for performance while allowing the system to cool between pulses. This segmentation of power delivery reduces cumulative heat dissipation and component stress.
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 significantly reduces power loss during operation and energy recovery, allowing for more efficient use of electrical energy and potentially higher voltages on the piezo component, while minimizing heat dissipation and component stress.
Implementation Method 1
a piezoelectric actuator and a membrane that can be deflected by the actuator
Data Source
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AI summary
The invention relates to a method for operating a piezoelectric MEMS sound transducer (4), in particular a MEMS loudspeaker and/or MEMS microphone operating in the audible wavelength spectrum and/or in the ultrasonic range, in which electrical energy is stored in at least one energy store (2) and this electrical energy is transferred between the energy store (2) and the piezoelectric MEMS sound transducer (4) indirectly via at least one transfer unit (3, 13). According to the invention, the at least one transfer unit (3, 13) and the piezoelectric MEMS sound transducer (4) are arranged in a parallel circuit (5) with respect to one another and are connected in such a manner that, in order to operate the piezoelectric MEMS sound transducer (4) in a first switching state, the at least one transfer unit (3) is first of all charged from the energy store (2) and this transfer unit (3) is then discharged again in a second switching state and the piezoelectric MEMS sound transducer (4) is charged in this case, and/or, in order to recover energy in a third switching state, the piezoelectric MEMS sound transducer (4) is discharged again and the at least one transfer unit (3, 13) is charged in this case and this transfer unit (3, 13) is then discharged again in a fourth switching state and the energy store (2) is charged in this case.