Piezoelectric Liquid Ejecting Head Frequency-Adaptive Voltage Control
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Solution Overview
Problem
Existing liquid ejecting apparatuses using piezoelectric elements face challenges in enhancing displacement characteristics while considering the drive frequency, as the coercive voltage shifts in high frequency bands due to circuit rate limiting.
Innovation Solution
The apparatus employs a liquid ejecting head with a piezoelectric body driven by a voltage applying section, where a reference voltage is applied to one electrode and a time-varying drive voltage to the other. The difference between the reference and minimum drive voltages is set higher than the coercive voltage at the first drive frequency but lower than at a second, lower drive frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the voltage applied to the piezoelectric body is set higher than the coercive voltage in the normal frequency band, then the displacement characteristics are improved, but in the high frequency band the coercive voltage shifts toward the negative side causing suboptimal performance
Solution Approach 1:
The patent applies dynamics by making the voltage application strategy frequency-dependent. The voltage applying section dynamically adjusts its behavior based on the drive frequency: applying a voltage higher than the coercive voltage at normal frequencies for enhanced displacement, and applying a voltage lower than the coercive voltage at high frequencies to account for the shift toward negative side, thereby optimizing performance across different frequency bands
Solution Approach 2:
The patent changes the voltage parameter based on frequency conditions. By detecting the drive frequency and selectively applying different voltage levels (higher than coercive voltage at normal frequencies, lower than coercive voltage at high frequencies), the system adapts the electrical parameter to match the piezoelectric body's frequency-dependent characteristics, resolving the contradiction between displacement optimization and frequency adaptability
2Stability of the object's composition
If the minimum value of the voltage applied to the piezoelectric body is set higher than the coercive voltage, then the range of voltage can be set in a range where polarization reversal is not completed, but this setting does not account for coercive voltage reduction in high frequency bands
Solution Approach 1:
The patent makes the voltage application dynamic by detecting the drive frequency and adjusting the voltage level accordingly. At normal frequencies, it maintains polarization stability by applying voltage higher than the coercive voltage. At high frequencies, it detects the coercive voltage shift and applies a lower voltage to prevent excessive polarization reversal, thereby maintaining stability across varying speeds
Solution Approach 2:
The patent implements feedback by having the voltage applying section detect the drive frequency and use this information to determine the appropriate voltage level to apply. This closed-loop approach ensures that the voltage applied to the piezoelectric body is always appropriate for the current operating frequency, maintaining polarization stability while adapting to high frequency conditions
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
This configuration enhances the displacement characteristics of the piezoelectric element at high frequencies, leading to increased ink ejection and improved printing performance compatible with high frequency driving.
Implementation Method 1
a piezoelectric body disposed between the first electrode and the second electrode... drives the piezoelectric body to eject a liquid
Data Source
AI summary
When the drive frequency of the piezoelectric body at which the liquid is ejected is defined as a first drive frequency, the coercive voltage of the piezoelectric body obtained when the piezoelectric body is driven at the first drive frequency is defined as a first coercive voltage, a drive frequency lower than the first drive frequency is defined as a second drive frequency, and the coercive voltage of the piezoelectric body obtained when the piezoelectric body is driven at the second drive frequency is defined as a second coercive voltage, the difference between the reference voltage and the minimum value of the drive voltage is higher than the first coercive voltage and is lower than the second coercive voltage.