Piezoelectric Driving Circuit Polarization Stability
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Solution Overview
Problem
Piezoelectric elements in liquid discharge apparatuses, such as ink jet printers, face operation failures due to disturbances in polarization direction caused by reverse polarity electric fields, leading to deteriorated piezoelectric characteristics and potential electrical short circuits.
Innovation Solution
A driving circuit and method that controls the potential difference between the first and second electrodes of the piezoelectric element to minimize reverse polarity electric fields, ensuring the piezoelectric element operates within a stable polarization direction by gradually transitioning the voltage to match the reference voltage during startup and maintaining equal potentials during standby, thus preventing unintended displacements and electrical shorts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a piezoelectric element is supplied with a driving signal that creates a potential difference between electrodes, then the piezoelectric element displaces to discharge ink, but an electric field in the opposite direction to the polarization DC electric field disturbs the polarization direction and deteriorates piezoelectric characteristics
Solution Approach 1:
The patent applies preliminary action by performing polarization processing on the piezoelectric body before incorporating it into the print head. This preliminary polarization aligns the polarization directions by applying a predetermined DC electric field, ensuring the piezoelectric characteristics are established before the element is subjected to operational driving signals. This prevents subsequent reverse polarity electric fields from causing operation failures.
Solution Approach 2:
The patent applies preliminary anti-action by designing the driving circuit to control the potential difference between electrodes such that the electric field direction does not oppose the polarization direction. The control unit adjusts the driving signal to ensure the electric field acts in the same direction as the polarization DC electric field, thereby preventing disturbance to the polarization direction and maintaining piezoelectric characteristics stability.
2Adaptability or versatility
If the piezoelectric element is subjected to reverse polarity electric fields, then polarization direction disturbance occurs, but this leads to operation failure and electrical short circuits
Solution Approach 1:
The patent converts the potential harm of reverse polarity electric fields into a benefit by designing the driving circuit to exclusively apply electric fields in the same direction as the polarization DC electric field. The control unit processes the driving signal to ensure the potential difference between electrodes always creates an electric field that reinforces rather than opposes the polarization direction, thereby eliminating the harmful effect of polarization disturbance while maintaining electrical signal response capability.
3Ease of operation
If the piezoelectric element operates with unstable polarization direction, then piezoelectric characteristics deteriorate, but this reduces the reliability of the liquid discharge apparatus
Solution Approach 1:
The patent applies parameter changes by carefully controlling the electrical parameters of the driving signal, specifically the potential difference between electrodes. The control unit adjusts the driving signal parameters to ensure the resulting electric field strength and direction maintain the polarization direction stability. By optimizing these electrical parameters, the system achieves both discharge control flexibility and polarization stability simultaneously.
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 polarization direction disturbances, maintains the piezoelectric characteristics, and prevents operation failures by ensuring the piezoelectric element operates within a stable electric field, enhancing the reliability and longevity of the liquid discharge apparatus.
Implementation Method 1
The piezoelectric element is provided in a print head corresponding to a plurality of nozzles for discharging the ink and a cavity for storing the ink discharged from the nozzles. Then, when the piezoelectric element is displaced in accordance with a driving signal, a diaphragm provided between the piezoelectric element and the cavity is bent, and a volume of the cavity is changed.
Data Source
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AI summary
There is provided a driving circuit that drives a discharge head which includes a piezoelectric element having a first electrode for supplying a first voltage signal and a second electrode for supplying a second voltage signal and driven by a potential difference between the first electrode and the second electrode, and which discharges a liquid by driving the piezoelectric element, the driving circuit including: a first voltage signal generation circuit for outputting the first voltage signal; a second voltage signal generation circuit for outputting the second voltage signal; and a switch circuit in which the first voltage signal is input from one end and the other end is electrically connected to the first electrode, in which a voltage value of the first voltage signal approaches a voltage value of the second voltage signal in a shift period in which a first mode to be shifted after power is turned on is shifted to a second mode for driving the piezoelectric element.