Piezoelectric Drive Circuit With Bootstrap Smoothing for Waveform Accuracy
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Solution Overview
Problem
Existing drive circuits for inkjet printers, particularly those using piezoelectric elements, face limitations in waveform accuracy of the drive signal, which affects the precision and efficiency of ink ejection.
Innovation Solution
A drive circuit design incorporating a first and second switching circuit, a bootstrap circuit, and a smoothing circuit to generate and smooth pulse signals, utilizing capacitive elements and diodes to optimize voltage supply and gate signal generation for improved waveform accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional amplifier circuit is used to drive the piezoelectric element, then the drive signal can be generated, but the waveform accuracy of the drive signal is insufficient
Solution Approach 1:
The drive circuit is divided into multiple switching circuits (first switching circuit, second switching circuit, third switching circuit) that operate in sequence to generate different portions of the drive signal waveform. Each switching circuit handles a specific voltage level or time period, allowing precise control of the overall waveform shape and improving waveform accuracy through segmented generation.
Solution Approach 2:
Bootstrap circuits are used to pre-charge capacitive elements to specific voltage levels before the main switching operation. This preliminary action ensures that when the switching circuits operate, they start from known voltage states, enabling accurate generation of the drive signal waveform without requiring complex real-time adjustments.
2Measurement precision
If multiple switching circuits and bootstrap circuits are added to improve waveform accuracy, then the drive signal quality improves, but the circuit complexity increases
Solution Approach 1:
Multiple switching circuits are merged into a coordinated system where the first, second, and third switching circuits work together in sequence. The bootstrap circuits are merged with the switching circuits, sharing common control signals and voltage references. This merging allows the complex functionality to be achieved through integrated operation rather than separate independent circuits.
Solution Approach 2:
The switching circuits are designed to perform multiple functions: voltage switching, waveform shaping, and timing control. The bootstrap circuits serve dual purposes of voltage pre-charging and reference level establishment. This multi-functionality reduces the need for additional dedicated circuits, managing complexity while maintaining waveform accuracy.
3Productivity
If the piezoelectric element is driven with insufficient current, then the circuit remains simple, but the ejection efficiency and operational stability deteriorate
Solution Approach 1:
The drive circuit uses periodic switching actions with multiple phases (first switching circuit, second switching circuit, third switching circuit operating in sequence). This periodic multi-phase operation delivers current in controlled pulses that are optimized for the capacitive nature of the piezoelectric element, improving ejection efficiency while managing power delivery in discrete energy packets rather than continuous high power.
Solution Approach 2:
The circuit dynamically changes voltage parameters through the switching circuits and bootstrap circuits, adjusting the voltage levels and timing to optimize current delivery to the piezoelectric element. By changing voltage parameters in a controlled sequence, the circuit achieves efficient energy transfer that improves ejection efficiency while minimizing unnecessary power loss.
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 proposed drive circuit enhances waveform accuracy and reduces power loss, leading to improved operational stability and efficiency in ink ejection processes.
Implementation Method 1
a first capacitive element of which one end is electrically coupled to the first output point, and a first diode of which a second voltage is supplied to an anode terminal, and a cathode terminal is electrically coupled to the other end of the first capacitive element
Implementation Method 2
a first diode of which a second voltage is supplied to an anode terminal, and a cathode terminal is electrically coupled to the other end of the first capacitive element
Implementation Method 3
a second capacitive element of which one end is electrically coupled to the second output point and the other end is electrically coupled to the second gate driver, and a second diode of which the first voltage is supplied to an anode terminal and a cathode terminal is electrically coupled to the other end of the second capacitive element
Implementation Method 4
a second diode of which the first voltage is supplied to an anode terminal and a cathode terminal is electrically coupled to the other end of the second capacitive element
Implementation Method 5
a smoothing circuit that smooths the second pulse signal and outputs the drive signal
Data Source
AI summary
A first switching circuit, a second switching circuit, a first bootstrap circuit that is coupled to the first switching circuit and the second switching circuit, and a smoothing circuit and outputs a drive signal are provided, in which the second switching circuit includes a second gate driver that outputs a third gate signal and a fourth gate signal, a third transistor of which the first voltage is supplied, and which is driven based on the third gate signal, a fourth transistor which is driven based on the fourth gate signal, and a second bootstrap circuit that includes a second capacitive element supplying a third voltage to the second gate driver and coupled to a second output point and the second gate driver, and a second diode of which the first voltage is supplied and which is coupled to the second capacitive element.