Piezoelectric Actuator for Ink-Jet Head with Constant Voltage Control
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Solution Overview
Problem
The existing ink-jet head technology experiences a decrease in liquid transport efficiency due to compression distortion in the piezoelectric layer caused by differences in linear expansion coefficients between the vibration plate and the piezoelectric layer, leading to reduced deformation and ink jetting performance.
Innovation Solution
A liquid transporting apparatus with a piezoelectric actuator that includes a piezoelectric layer, electrodes, and a voltage applying mechanism, where a constant voltage is applied between auxiliary electrodes and the common electrode to contract the piezoelectric layer in a planar direction, reducing compression distortion and maintaining efficient ink transport.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the vibration plate and piezoelectric layer are joined by heating, then they are securely bonded, but compression distortion occurs in the piezoelectric layer due to differential thermal expansion
Solution Approach 1:
The patent changes the physical state of the adhesive from solid to liquid by heating, enabling secure bonding. The vibration plate and piezoelectric layer are heated to a temperature where the adhesive melts and bonds the components together, resolving the contradiction between bonding strength and dimensional stability.
Solution Approach 2:
The patent introduces a cushioning layer between the vibration plate and piezoelectric layer to compensate for the compression distortion caused by differential thermal expansion. This cushioning layer absorbs the dimensional changes during heating and cooling, preventing permanent distortion of the piezoelectric layer while maintaining secure bonding.
2Strength
If the piezoelectric layer is compressed due to thermal expansion difference, then bonding is maintained, but piezoelectric characteristics are declined and deformation amount is reduced
Solution Approach 1:
The cushioning layer is positioned between the vibration plate and piezoelectric layer to preemptively absorb compression forces during thermal cycling. This prevents the transmission of compressive stress to the piezoelectric layer, maintaining both bonding integrity and piezoelectric characteristics without degradation.
Solution Approach 2:
The cushioning layer acts as an intermediary element between the vibration plate and piezoelectric layer. It mediates the mechanical stress transmission during thermal expansion and contraction, protecting the piezoelectric layer from direct compression while maintaining the structural connection.
3Strength
If a thermosetting adhesive is used to join the vibration plate and piezoelectric layer, then strong bonding is achieved, but heating causes compression distortion in the piezoelectric layer
Solution Approach 1:
The patent utilizes the temperature-dependent properties of the thermosetting adhesive, heating it to its melting point to achieve bonding. The adhesive transitions from solid to liquid state during heating, then solidifies upon cooling to create a strong permanent bond between the vibration plate and piezoelectric layer.
Solution Approach 2:
The cushioning layer is introduced to compensate for the dimensional changes that occur during the heating and cooling process required for thermosetting adhesive bonding. It absorbs the compression distortion that would otherwise occur in the piezoelectric layer due to differential thermal expansion between materials.
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 solution prevents the reduction in deformation and ink transport efficiency by minimizing compression distortion in the piezoelectric layer, ensuring consistent ink jetting performance and simplifying electrode wiring configurations.
Implementation Method 1
by applying a voltage between the vibration plate as a common electrode and one of the individual electrodes, an electric field is generated at a portion, of the piezoelectric layer, sandwiched between the common electrode and the individual electrode in a thickness direction of the piezoelectric layer, and portions of the vibration plate and the piezoelectric layer which face the pressure chamber are deformed to form a projection toward the pressure chamber
Implementation Method 2
when the temperature is returned to a room temperature after heating, there is a compression distortion in a planar direction of the piezoelectric layer due to a difference in the coefficient of linear expansion of the vibration plate and the piezoelectric layer
Data Source
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AI summary
A liquid transporting apparatus includes a channel unit (31) with a liquid transporting channel including a pressure chamber (10); a piezoelectric actuator (32) which is connected to the channel unit, and having: a piezoelectric layer (42); a first electrode (43) arranged on a first surface of the piezoelectric layer; a second electrode (45) arranged opposite the first electrode, on a second surface of the piezoelectric layer; third electrodes (44) arranged on the piezoelectric layer to sandwich the first electrode in a plan view; and fourth electrodes (45) which are arranged, to face the third electrode, on the piezoelectric layer; a voltage applying mechanism which applies a voltage to the piezoelectric actuator; and a controller (100) which controls the voltage applying mechanism to apply a voltage between the first and second electrode to deform the piezoelectric layer facing the pressure chamber and to apply a predetermined constant voltage between the third and fourth electrodes during the pressure applying operation.