Piezoelectric Actuator Bending Rigidity Control for Liquid Ejecting Heads
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Solution Overview
Problem
The existing liquid ejecting heads face challenges in actuator displacement due to varying bending rigidity along the pressure chamber, leading to inefficient ink ejection and potential damage from excessive deformation.
Innovation Solution
The liquid ejecting head incorporates a piezoelectric element with a specific electrode and piezoelectric body configuration, and a vibrating plate with varying thickness and bending rigidity along the pressure chamber, where the bending rigidity at the end portion is set to be between 35% and 85% of the central portion's rigidity, optimizing actuator displacement and preventing damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the thickness of the actuator is made uniform throughout the pressure chamber, then the manufacturing is simplified, but the actuator displacement becomes insufficient at the end portions due to high rigidity
Solution Approach 1:
The actuator's thickness is made non-uniform, with the end portions having smaller thickness than the central portion. This creates different rigidity characteristics in different regions: the central portion maintains sufficient rigidity for stable operation, while the end portions have reduced rigidity to enable adequate displacement for liquid ejection.
2Strength
If the thickness of the actuator at the end portion is reduced to improve displacement, then the actuator displacement at end portions increases, but the displacement at the central portion becomes insufficient
Solution Approach 1:
The actuator is designed with spatially varying thickness: the end portions have reduced thickness (e.g., 50-70% of the central thickness) to improve displacement, while the central portion maintains greater thickness to preserve sufficient displacement capability and structural stability.
3Strength
If the bending rigidity at the end portion is too low relative to the central portion, then the actuator displacement at end portions improves, but the actuator becomes prone to cracking and damage
Solution Approach 1:
The bending rigidity ratio between the end portion and central portion is optimized to a specific range (e.g., 0.35 ≤ FR2/FR1 < 1.0). This parameter control ensures that the end portions have sufficient flexibility for displacement while maintaining enough structural integrity to prevent cracking and damage during operation.
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 enables efficient actuator displacement while maintaining ink ejection performance and preventing cracking, allowing for controlled ejection of ink from multiple pressure chambers.
Implementation Method 1
an actuator that includes a piezoelectric element which includes a first electrode, a second electrode, and a piezoelectric body and in which the piezoelectric body is provided between the first electrode and the second electrode in a thickness direction
Data Source
AI summary
A liquid ejecting head includes: an actuator including a piezoelectric element and a vibrating plate; and a pressure chamber substrate including a pressure chamber whose volume changes when the vibrating plate deforms, in which 0.35×FR1≤FR2<1.00×FR1, where one position in a longitudinal direction of the pressure chamber is a first position, another position closer than the first position to an end of the pressure chamber in the longitudinal direction of the pressure chamber is a second position, bending rigidity of the actuator in the thickness direction at the first position is FR1, and bending rigidity of the actuator in the thickness direction at the second position is FR2.