Driving Circuit Delays Power Stop to Prevent Reverse Polarity in Piezo Elements
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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, which deteriorate their characteristics and lead to potential electrical short circuits and loss of function.
Innovation Solution
A driving circuit with an integrated circuit that generates amplification control signals for a piezoelectric element, includes registers for holding operating and abnormality detection data, and an output control circuit that delays the stop of power source voltage to the switch circuit relative to the stop of voltage signals to the piezoelectric element, ensuring controlled voltage supply and minimizing reverse polarity exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a piezoelectric element is driven by a potential difference between first and second electrodes, then liquid discharge is achieved, but reverse polarity electric fields cause disturbance in polarization direction and deterioration of piezoelectric characteristics
Solution Approach 1:
The output control circuit performs preliminary action by delaying the stop of power source voltage supply to the switch circuit relative to the stop of drive voltage signals. This ensures that the switch circuit maintains power supply during the transition period, preventing the generation of reverse polarity electric fields that would disturb the piezoelectric element's polarization direction and maintain reliable operation.
2Speed
If the power source voltage is stopped simultaneously with the voltage signals to the piezoelectric element, then the circuit response is fast, but reverse polarity electric fields may occur causing operation failure
Solution Approach 1:
The output control circuit extends the power source voltage supply period as a preliminary protective measure. By maintaining power supply to the switch circuit after the drive voltage signals are stopped, the circuit prepares for and prevents the occurrence of reverse polarity electric fields, ensuring reliable operation while maintaining reasonably fast response through controlled timing extension.
3Manufacturing precision
If the piezoelectric element is subjected to polarization processing with DC electric field, then piezoelectric characteristics are realized, but subsequent reverse polarity fields disturb the aligned polarization direction
Solution Approach 1:
The output control circuit applies preliminary anti-action by controlling the timing of power source voltage cessation. This prevents the harmful reverse polarity electric field from occurring in the first place, thereby protecting the polarization alignment achieved during manufacturing and maintaining the piezoelectric element's performance over time.
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 and operation failures, maintaining the piezoelectric characteristics and extending the lifespan of the piezoelectric elements by ensuring controlled voltage supply and minimizing reverse polarity exposure.
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
AI summary
There is provided a driving circuit that drives a piezoelectric element, the driving circuit including an integrated circuit, in which the integrated circuit includes a first register that holds an operating state data, a second register that holds an abnormality detection data, an abnormality detection circuit that determines the presence or absence of an abnormality of the operating state data based on the abnormality detection data, and an output control circuit that controls supply of a first voltage signal to the piezoelectric element and supply of a power source voltage to the switch circuit, and in which the output control circuit delays stop of the supply of the power source voltage to the switch circuit with respect to stop of the supply of the first voltage signal to the piezoelectric element when the abnormality detection circuit determines that the operating state data is abnormal.