Capacitive Load Driving Circuit With Tracking Supply Voltages
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Solution Overview
Problem
Existing driving circuits for capacitive loads in inkjet recording apparatuses face challenges in reducing power consumption, especially at high frequencies, due to increased power consumption by transistors and instability caused by delays in smoothing circuits, making it difficult to maintain stable operation.
Innovation Solution
A driving circuit that uses a complementary transistor pair for generating driving signals and a power source voltage generating unit with a capacitor to produce high and low voltage power source voltages that follow the driving signal, reducing voltage differences and power consumption, and stabilizing operation by adjusting the control signal waveform.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the current of the driving signal is amplified by a current amplifying unit, then the piezoelectric elements can operate without problem, but the power consumption of the transistors is increased
Solution Approach 1:
The patent changes the voltage parameters of the power source by generating auxiliary power source voltages that are offset from the main driving signal. Specifically, it generates a high-voltage power source voltage higher than the main driving signal and a low-voltage power source voltage lower than the main driving signal, thereby changing the voltage difference parameter to reduce power consumption while maintaining reliable operation
Solution Approach 2:
The patent segments the power source voltage into multiple levels by using separate voltage generation circuits for high-voltage and low-voltage power sources. This segmentation allows independent control of voltage levels to optimize the voltage difference across transistors, reducing power consumption while ensuring reliable piezoelectric element operation
2Use of energy by moving object
If an auxiliary driving signal offset by a predetermined amount is generated to follow the main driving signal, then the power consumption is reduced, but the operation becomes unstable due to delay in the smoothing circuit
Solution Approach 1:
The patent makes the power source voltage dynamic by generating auxiliary voltages that actively follow the waveform of the main driving signal. The voltage generation circuits are designed to dynamically adjust the high-voltage and low-voltage power source levels in response to the main driving signal variations, maintaining optimal voltage differences throughout the signal cycle and ensuring stable operation at high frequencies
Solution Approach 2:
The patent implements a feedback mechanism where the auxiliary driving signal is generated based on the main driving signal waveform. The voltage generation circuits continuously monitor and respond to the main driving signal, adjusting the power source voltages to maintain the desired offset relationship, thereby compensating for delays and ensuring operational stability
3Productivity
If the frequency of the main driving signal is increased, then the productivity is improved, but the influence of delay in the smoothing circuit cannot be ignored
Solution Approach 1:
The patent applies preliminary action by pre-generating the auxiliary driving signal with the appropriate offset before it is needed for power source voltage generation. This advance preparation ensures that when the high-frequency main driving signal arrives, the power source voltages are already positioned to maintain stable operation, compensating for any delays in the voltage generation process
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 effectively reduces power consumption and maintains stable operation even at high frequencies by generating high and low voltage power source voltages that closely follow the driving signal, thereby decreasing power consumption and minimizing the impact of delays.
Implementation Method 1
an ink jet record head that drives a piezoelectric element by using a driving signal having a trapezoidal shape
Implementation Method 2
a capacitor of which low-voltage terminal is connected to an output side of the power source transistor pair... the high-voltage power source voltage is output from a high-voltage terminal of the capacitor as a voltage that is acquired from adding a charged voltage of the capacitor to the low-voltage power source voltage
Data Source
AI summary
A driving circuit for a capacitive load includes a driving signal generating unit that generates a driving signal for driving the capacitive load by using a pair of driving transistors. A power source voltage generating unit generates high-voltage and low-voltage power source voltages that are higher and lower, respectively, than the voltage of the driving signal and applies the voltages to collectors of the driving transistors. The power source voltage generating unit includes a pair of power source transistors and a capacitor. The low-voltage power source voltage is generated in an output side of the power-source transistor pair as a voltage that is in a voltage region lower than that of the driving signal and follows the driving signal. The high-voltage power source voltage is output from a high-voltage terminal of the capacitor, is in a voltage region higher than that of the driving signal, and follows the driving signal.