Drive Circuit Voltage Stabilization for Capacitive Loads
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Solution Overview
Problem
Existing drive circuits for capacitive loads, such as piezoelectric elements, experience unstable voltage variations due to feedback and pulse modulation, leading to self-oscillation issues that affect the reliability of the drive signal.
Innovation Solution
A drive circuit configuration that includes a signal generating circuit, arithmetic circuit, modulation circuit, digital power amplifier circuit, smoothing circuit, compensation circuit, and a voltage generating circuit, which generates a first voltage exceeding the voltage range where pulse frequency does not vary with respect to drive signal voltage, ensuring the drive signal is supplied after the initial voltage is set, thereby stabilizing the voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pulse modulation is performed with feedback of the drive signal, then the drive signal is generated, but voltage variation occurs due to self-oscillation
Solution Approach 1:
The patent applies preliminary action by setting the drive signal voltage to a predetermined voltage value before starting pulse modulation. This preliminary voltage setting prevents the occurrence of self-oscillation during the modulation process, thereby maintaining voltage stability and eliminating the harmful voltage variations that would otherwise occur.
2Productivity
If feedback signal is used to advance phase, then the drive signal is generated, but voltage varies unstably
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the drive signal voltage based on the operation state of the power amplifier circuit. When the power amplifier is not operating, the voltage is set to a predetermined value; when operating, it switches to a different voltage level. This parameter change prevents self-oscillation during transitions and maintains voltage stability throughout the drive signal generation process.
Data Source
AI summary
A drive circuit includes a signal generating circuit that generates drive waveform signal, an arithmetic circuit that generates difference signal representing a difference between the drive waveform signal and a feedback signal, a modulation circuit that modulates the difference signal pulse to generate modulated signal, a digital power amplifier circuit that amplifies the modulated signal to generate amplified signal, a smoothing circuit that smoothes the amplified signal to generate drive signal, a compensation circuit that generates the feedback signal based on the drive signal, and a voltage generating circuit that is connected to wiring between the digital power amplifier circuit and the capacitive load and generates a first voltage that exceeds a voltage range in which a pulse frequency of the modulated signal does not vary with respect to voltage variation of the drive signal, the drive signal being supplied to the capacitive load after the first voltage.