Boosting Circuit Synchronization for Noise-Immune Piezoelectric Driving
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Solution Overview
Problem
In liquid discharging apparatuses, such as ink jet printers, the use of class-D amplifiers for piezoelectric elements leads to noise-related malfunctions and reduced discharge accuracy due to high oscillation frequencies, and synchronizing the boosting clock with self-excited oscillation is challenging, especially when reducing circuit size.
Innovation Solution
A liquid discharging apparatus with a modulation portion generating a pulse-modulated signal, a gate driver generating an amplification control signal, and a boosting circuit that controls voltage based on first and second clock signals, where the switching point of the second clock signal is synchronized with the modulation signal to minimize noise influence and maintain self-excited oscillation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a class-D amplifier with self-excited oscillation type modulation is used to drive piezoelectric elements, then energy efficiency is improved, but noise from the boosting circuit causes malfunction and deteriorates discharge accuracy
Solution Approach 1:
The patent applies preliminary action by generating a synchronization signal before the self-excited oscillation occurs to control the boosting circuit. The synchronization signal is generated based on a clock signal before the modulation signal from self-excited oscillation is available, ensuring the boosting circuit operates reliably from the start without causing malfunctions due to noise.
2Reliability
If the boosting clock is synchronized with the self-excited oscillation signal, then noise influence is reduced, but the self-excited oscillation may stop when circuit size is reduced
Solution Approach 1:
The patent introduces a synchronization signal as an intermediary between the clock signal and the boosting circuit control. This synchronization signal serves as a mediator that translates the clock signal into a form that can properly control the boosting circuit without directly relying on the self-excited oscillation signal, thus preventing oscillation stoppage while maintaining noise immunity.
Solution Approach 2:
The synchronization signal is generated in advance based on the clock signal before the self-excited oscillation occurs. This preliminary generation ensures that the boosting circuit has a stable control signal from the beginning, preventing the oscillation from stopping while still achieving proper synchronization to minimize noise influence.
3Measurement precision
If high oscillation frequency (1 MHz to 8 MHz) is used to achieve high output waveform accuracy, then discharge accuracy is improved, but noise from the boosting circuit increases and causes malfunction
Solution Approach 1:
The patent employs feedback by using a synchronization signal that is generated based on the clock signal and fed back to control the boosting circuit. This feedback mechanism ensures that the boosting circuit operates in synchronism with the modulation signal, minimizing noise influence while maintaining the high oscillation frequency necessary for output waveform accuracy.
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 reduces the impact of noise from the boosting circuit on the driving signal, preventing malfunctions and maintaining discharge accuracy, while allowing the boosting circuit to continue operating effectively even after self-excited oscillation initiation.
Implementation Method 1
a piezoelectric element which is displaced as the driving signal is applied
Data Source
AI summary
There is provided a driving circuit for driving a capacitive load including: a modulation portion which generates a modulation signal pulse-modulated from a source signal; a gate driver which generates an amplification control signal based on the modulation signal; a transistor which generates an amplification modulation signal amplified from the modulation signal based on the amplification control signal; a low pass filter which demodulates the amplification modulation signal and generates a driving signal; a feedback circuit which sends back the driving signal to the modulation portion; a boosting circuit which supplies a voltage which has been boosted.