Piezoelectric Liquid Discharge Head Stress Control for Plate Deflection
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Solution Overview
Problem
Existing liquid discharge heads face inefficiencies due to excessive deflection of the vibration plate when the piezoelectric element is not driven, limiting the displacement amount and reducing discharge efficiency.
Innovation Solution
A liquid discharge head design with a laminated structure of a pressure chamber substrate, vibration plate, and piezoelectric element, incorporating an elastic film and insulating film with specific stress relationships (X>−0.48Z−904) to optimize the initial deflection and enhance displacement efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the vibration plate is in a state of being deflected toward the pressure chamber when the piezoelectric element is not driven, then the initial deflection is large, but the displacement amount of the vibration plate reaches the limit even when an attempt is made to further displace the vibration plate by driving the piezoelectric element
Solution Approach 1:
The patent applies parameter changes by precisely controlling the film stress parameters of the elastic film and insulating film. By satisfying the specific mathematical relationship X>−0.48Z−904 between the film stress X of the elastic film and the film stress Z of the insulating film, the initial deflection of the vibration plate is optimized to an appropriate level, preventing excessive deflection that would limit subsequent displacement range.
Solution Approach 2:
The patent uses composite materials by combining the elastic film and insulating film in a laminated structure. This composite structure allows for independent optimization of each layer's stress characteristics, enabling precise control over the overall film stress and thus the initial deflection of the vibration plate while maintaining electrical insulation.
2Ease of manufacture
If the film stress of the elastic film and insulating film are not optimized, then the manufacturing process is simpler, but the displacement efficiency of the vibration plate is insufficient
Solution Approach 1:
The patent transforms the manufacturing approach by introducing specific parameter control requirements for film stress. By establishing the quantitative relationship X>−0.48Z−904, the patent converts a qualitative design into a quantitative control specification, enabling precise adjustment of vibration plate characteristics through film stress optimization during the manufacturing process.
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 optimized stress relationships reduce initial deflection, allowing for improved displacement efficiency and effective liquid discharge by ensuring the vibration plate does not reach its elastic deformation limit prematurely.
Implementation Method 1
a piezoelectric element that vibrates the vibration plate
Implementation Method 2
a film stress of the elastic film is X (MPa), and a film stress of the insulating film is Z (MPa), and X>−0.48Z−904
Data Source
AI summary
There is provided a liquid discharge head including: a piezoelectric element; a pressure chamber substrate provided with a pressure chamber that communicates with a nozzle; and a vibration plate configured to apply a pressure to a liquid in the pressure chamber by vibrating when the piezoelectric element is driven, in which the pressure chamber substrate, the vibration plate, and the piezoelectric element are laminated in this order in a lamination direction, the vibration plate includes an elastic film provided on the pressure chamber substrate and an insulating film provided between the elastic film and the piezoelectric element, and X>−0.48Z−904, where a compressive stress is represented by a negative value, a tensile stress is represented by a positive value, a film stress of the elastic film is X [MPa], and a film stress of the insulating film is Z [MPa].