Inkjet Head Electrode Insulation via Groove Trimming
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Solution Overview
Problem
The insulation property of the protective film in inkjet heads is insufficient at the end portions of the piezoelectric body, leading to potential electrolysis of ink due to electrical contact, which can cause ink ejection failures.
Innovation Solution
A method for manufacturing inkjet heads involves forming a conductive film on the inner surface of grooves in the piezoelectric body, ensuring it is separated from the top portion and slant surfaces, and covering it with insulating films to prevent electrical contact with ink, using a substrate, nozzle plate, and piezoelectric actuators with slant surfaces and grooves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protective film is formed to cover the electrode in the groove, then the electrode is protected, but the insulating property at the end portions of the piezoelectric body remains insufficient
Solution Approach 1:
The electrode is designed to extend beyond the groove toward the end portion of the piezoelectric body before the protective film is applied. This preliminary positioning allows the protective film to cover both the electrode surface and the critical end portion area, ensuring sufficient insulation is established before any harmful contact can occur.
Solution Approach 2:
The protective film is extended not only to cover the groove area but also to reach and cover the end portion of the piezoelectric body where the electrode extends. This dimensional extension of the protective film coverage from just the groove to include the end portion eliminates the insulation gap that previously allowed electrolysis.
2Area of moving object
If the electrode is formed to extend to the upper surface of the piezoelectric body, then the electrode area is increased, but the nozzle plate deformation is prevented or reduced
Solution Approach 1:
The electrode is designed with non-uniform distribution: it extends beyond the groove in the central area to increase effective electrode area for better actuation, but deliberately does not extend to the very end portions of the piezoelectric body. This local differentiation allows the electrode to have sufficient area for performance while avoiding the end regions where it would constrain nozzle plate deformation necessary for ink ejection.
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 enhances the insulation of the electrode, preventing electrolysis and ensuring reliable ink ejection by maintaining the electrode's area and deformation, thus improving the operational stability of the inkjet head.
Implementation Method 1
A piezoelectric element, also referred to as a piezo element, included in the piezoelectric body, is an electromechanical conversion element to convert a voltage into force. The deformation of the piezoelectric element is used to generate pressure in ink contained in the ink pressure chamber.
Implementation Method 2
forming an insulating film over the conductive film... covering it with insulating films to prevent electrical contact with ink
Data Source
AI summary
According to one embodiment, a method for manufacturing an inkjet head includes attaching a piezoelectric body facing the substrate, forming slanting side surfaces on the piezoelectric body, the slanting side surfaces extending between a first surface and a second surface of the piezoelectric body such that first surface has a remaining area that is less that a remaining area of second surface, forming a groove in the piezoelectric body from the first surface towards the second surface, the groove passing through two slanting side surfaces on opposite sides of the piezoelectric body, forming a conductive film on an inner surface of the groove, trimming portions of the conductive film proximate to the first surface and the slanting side surfaces such that the conductive film is separated from the first surface and the slanting side surfaces at outer edges of the groove, and forming an insulating film over the conductive film.