Piezoelectric Drive Circuit Stabilization Sequence
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Solution Overview
Problem
Piezoelectric elements in liquid ejecting apparatuses, such as inkjet printers, experience degradation in piezoelectric characteristics when an electric field opposite to the polarized DC electric field is applied, leading to abnormal operations due to disorder in polarization directions.
Innovation Solution
A drive circuit is designed with a drive signal output circuit, a switch circuit, and a reference voltage signal output circuit, where the switch circuit is controlled to be non-conductive before the reference voltage signal is output, and the drive signal output circuit supplies a constant voltage signal, ensuring that the piezoelectric element is not driven until the reference voltage is stabilized, thereby preventing reverse voltage application and maintaining polarization alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a drive signal is supplied to the piezoelectric element before the reference voltage is stabilized, then the liquid ejecting apparatus can start operating earlier, but the piezoelectric characteristics may be degraded due to reverse voltage application
Solution Approach 1:
The reference voltage signal output circuit is activated in advance before the drive signal is supplied to the piezoelectric element. This preliminary action ensures that the reference voltage is already stabilized when the drive signal arrives, preventing any reverse voltage application and protecting the piezoelectric characteristics while enabling immediate operational readiness.
Solution Approach 2:
The switch circuit is configured to block the drive signal path before the reference voltage is ready, and only allows the drive signal to pass after the reference voltage is stabilized. This preliminary protective action prevents the harmful reverse voltage from reaching the piezoelectric element, ensuring reliability while maintaining startup speed.
2Productivity
If the switch circuit is kept conductive continuously, then the drive signal can be supplied immediately, but unintended stress may be applied to the piezoelectric element during voltage transitions
Solution Approach 1:
The reference voltage signal output circuit is activated in advance to establish a stable reference voltage level before the drive signal is allowed to pass through the switch circuit. This preliminary preparation ensures that when the switch closes, both the drive signal and reference voltage are at safe, stable levels, preventing unintended stress on the piezoelectric element.
Solution Approach 2:
The switch circuit acts as an intermediary between the drive signal output circuit and the piezoelectric element. It mediates the connection by remaining open during voltage transitions and only closing when both the drive signal and reference voltage are stable, thereby preventing harmful stress while maintaining productivity.
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 prevents unintended stress and reverse voltage application to the piezoelectric element, reducing the likelihood of abnormal operations and maintaining the piezoelectric characteristics, ensuring stable and consistent ink ejection performance.
Implementation Method 1
the piezoelectric element, which is included in a print head, is provided to correspond to a plurality of nozzles for ejecting ink and a cavity for storing the ink ejected from the nozzles. As the piezoelectric element is displaced according to a drive signal, a vibration plate provided between the piezoelectric element and the cavity bends, and a volume of the cavity changes.
Data Source
AI summary
A drive circuit includes a drive signal output circuit that outputs a drive signal supplied to the piezoelectric element and a first constant voltage signal that is constant at a first voltage value; a switch circuit having one end electrically coupled to an output terminal of the drive signal output circuit and the other end electrically coupled to the first terminal of the piezoelectric element, and a reference voltage signal output circuit that is electrically coupled to the second terminal of the piezoelectric element and outputs a second constant voltage signal which is constant at a second voltage value, in which before the reference voltage signal output circuit starts to output the second constant voltage signal, the one end and the other end of the switch circuit are controlled to be non-conductive, and the drive signal output circuit outputs the first constant voltage signal.