Capacitive Load Driving Circuit Voltage Control
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Solution Overview
Problem
Liquid discharging apparatuses, such as ink jet printers, face challenges in safely stopping operations when abnormal conditions, like power source voltage fluctuations, occur, leading to potential overloads in piezoelectric elements due to the lack of effective control mechanisms.
Innovation Solution
A capacitive load driving circuit with a detection portion that generates a modulation signal, amplifies it using a switching element, and controls the driving signal voltage based on power source voltage levels, ensuring safe operation by preventing continuous high-voltage input to the piezoelectric elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a class-D amplifier is used to drive piezoelectric elements, then energy efficiency is improved, but the ability to safely stop during abnormal conditions deteriorates
Solution Approach 1:
The patent implements a feedback mechanism where the detection portion monitors the power source voltage and provides this information to the control portion. The control portion then adjusts the driving signal voltage based on the detected voltage level, creating a closed-loop system that enables safe operation during abnormal conditions while maintaining energy efficiency of the class-D amplifier
Solution Approach 2:
The detection portion detects lowering of the power source voltage in advance before damage can occur to the piezoelectric elements. By performing this detection beforehand and triggering appropriate control actions, the system prevents over-load conditions and ensures safe stopping before failures occur
2Power
If high voltage driving signals are continuously input to piezoelectric elements, then driving performance is maintained, but the risk of over-load and damage increases during abnormal conditions
Solution Approach 1:
The patent makes the driving signal voltage dynamic rather than fixed. The control portion adjusts the voltage level of the driving signal in real-time based on the detected power source voltage. During normal operation, high voltage maintains driving performance, but during abnormal conditions, the voltage is reduced to prevent over-load, thus adapting the system behavior to current operating conditions
Solution Approach 2:
The patent changes the voltage parameter of the driving signal based on the power source voltage level. When the power source voltage is normal, the driving signal uses high voltage for optimal performance. When the power source voltage drops, the control portion changes the driving signal voltage to a lower level, preventing over-load conditions while maintaining acceptable operation
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 the risk of overloads by controlling the driving signal voltage, allowing the apparatus to safely stop during abnormal conditions, thereby maintaining operational integrity and preventing damage.
Implementation Method 1
a piezoelectric element that is displaced by applying the driving signal
Data Source
AI summary
A liquid discharging apparatus includes a modulation portion that generates a modulation signal obtained by pulse-modulating a source signal; a switching element that generates an amplification modulation signal obtained by amplifying the modulation signal; a low-pass filter that generates a driving signal by demodulating the amplification modulation signal; a piezoelectric element that is displaced by applying the driving signal; a selection portion that is configured to include a transistor and selects whether or not the driving signal is applied to the piezoelectric element; and a detection portion that detects lowering of a power source voltage supplied to the selection portion. The detection portion performs control for lowering a voltage of the driving signal if lowering of the power source voltage is detected.