Piezoelectric Liquid Ejecting Head Electrode Width Optimization
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Solution Overview
Problem
The existing liquid ejecting heads with piezoelectric elements face a challenge in optimizing the excluded volume, which affects the efficiency of liquid ejection, as increasing the width of the lower electrode film to enhance the active section area leads to reduced deformation of the vibration plate and subsequently decreases the excluded volume.
Innovation Solution
The solution involves forming the first electrode layer with a width of 50% or more and 80% or less of the pressure chamber width, and the piezoelectric body layer with a width of 90% or less of the pressure chamber width, optimizing the ratio to improve the excluded volume and enhance liquid ejection efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the width of the lower electrode film is increased to enhance the active section area, then the excluded volume may be reduced due to inhibited vibration plate deformation
Solution Approach 1:
The piezoelectric body layer is divided into multiple sections along the width direction, with each section having different widths. This segmentation allows different regions to serve different functions: some regions provide insulation coverage while others allow vibration plate deformation, thus resolving the contradiction between active section area and excluded volume
Solution Approach 2:
Different regions of the piezoelectric body layer are designed with different local properties - some regions have full width coverage for insulation, while other regions have reduced width to permit vibration plate deformation. This local differentiation enables both adequate insulation and sufficient excluded volume
2Reliability
If the width of the piezoelectric body layer is increased to cover the lower electrode film for suppressing insulation breakdown, then the width of the region where the piezoelectric body layer is not laminated is reduced, inhibiting vibration plate deformation
Solution Approach 1:
The piezoelectric body layer is segmented into multiple width sections, creating a pattern where insulated regions and deformation regions are alternately arranged. This segmentation ensures that insulation breakdown is prevented in covered regions while vibration plate deformation is permitted in uncovered regions
Solution Approach 2:
The piezoelectric body layer exhibits spatially varying width characteristics, with local regions providing full coverage for insulation and other local regions providing reduced coverage for deformation. This local quality differentiation simultaneously achieves insulation reliability and excluded volume requirements
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 allows for improved excluded volume and more efficient liquid ejection from the nozzles, ensuring a sufficient ejection performance by maintaining a balance between the electrode layer widths and the pressure chamber dimensions.
Implementation Method 1
a piezoelectric element is preferably used. For example, the piezoelectric element is configured such that a lower electrode film that functions as an individual electrode provided for each pressure chamber, a piezoelectric body layer of lead zirconate titanate (PZT) and the like, and an upper electrode film that functions as a common electrode common to a plurality of pressure chambers are respectively laminated
Implementation Method 2
The vibration plate has flexibility and is deformed depending on the deformation of the piezoelectric element
Data Source
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AI summary
A liquid ejecting head includes a pressure chamber forming substrate in which a plurality of spaces to be pressure chambers in communication with nozzles are provided side by side in a nozzle column direction, in which in a region corresponding to the pressure chamber, a lower electrode film is formed with a width of 50% or more and 80% or less of a width of the pressure chamber in the nozzle column direction and the piezoelectric body layer covers the lower electrode film in the nozzle column direction and is formed with a width of 90% or less of the width of the pressure chamber.