Liquid Discharge Head Venting Hole Reduces Air Expansion
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Solution Overview
Problem
Conventional liquid discharge heads face malfunctions due to air expansion causing separation of the flexible wiring substrate from the piezoelectric actuator substrate, leading to contact between electrodes and liquid, which results in malfunction.
Innovation Solution
Incorporating a first hole that allows communication between the space surrounded by the piezoelectric actuator substrate, flexible wiring substrate, and adhesive member, and the outside, reducing the likelihood of air expansion and subsequent separation, thereby preventing liquid contact with the electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the space surrounded by the piezoelectric actuator substrate, flexible wiring substrate, and adhesive member is closed, then the individual electrodes are isolated from liquid, but air expansion causes separation of the flexible wiring substrate from the piezoelectric actuator substrate
Solution Approach 1:
The patent divides the internal space into two separate functional zones: a liquid-tight sealed space for protecting individual electrodes from liquid contact, and a ventilated space for accommodating air expansion without causing substrate separation. This segmentation resolves the contradiction by allowing each zone to fulfill its specific function independently.
Solution Approach 2:
The patent introduces a partition wall as an intermediary structure between the liquid-tight sealed space and the ventilated space. This partition wall physically separates the two spaces while allowing the overall structure to maintain both liquid protection and pressure equalization functions, thus resolving the contradiction between electrode protection and substrate adhesion stability.
2Object-affected harmful factors
If the space is sealed to prevent liquid contact with electrodes, then electrode protection is improved, but heat transfer causes air expansion leading to substrate separation
Solution Approach 1:
The patent segments the internal volume into a liquid-tight sealed space for electrode protection and a ventilated space for pressure relief. This allows the structure to simultaneously protect electrodes from liquid while accommodating thermal expansion stresses without causing substrate separation.
Solution Approach 2:
The patent extracts the air venting function from the liquid-tight sealed space by creating a separate ventilated space. This extraction allows the liquid protection function to remain intact while the pressure management function is handled independently through the ventilation hole, resolving the stress accumulation problem.
3Reliability
If adhesive member surrounds individual electrodes to prevent liquid contact, then electrode protection is improved, but manufacturing complexity increases
Solution Approach 1:
The patent replaces the complex adhesive application process with a simpler partition wall structure that naturally creates the liquid-tight seal. This segmentation approach eliminates the need for precise adhesive application around each electrode, significantly simplifying the manufacturing process while maintaining reliable liquid protection.
Solution Approach 2:
The patent extracts the sealing function from the adhesive member and implements it through a structural partition wall with integrated liquid-tight seals. This extraction simplifies manufacturing by using rigid structural components instead of requiring precise application of flexible adhesive materials around sensitive electrodes.
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 effectively reduces the occurrence of malfunctions on the piezoelectric actuator substrate by minimizing the risk of liquid contact with the electrodes, ensuring stable operation.
Implementation Method 1
A piezoelectric actuator substrate having thereon a plurality of individual electrodes for pressurizing the pressurizing chambers is disposed on the flow channel member
Implementation Method 2
The flexible wiring substrate is adhered to the piezoelectric actuator substrate with, for example, an adhesive member interposed therebetween
Data Source
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AI summary
The present invention provides a liquid discharge head and a recording apparatus each capable of reducing the possibility that a malfunction occurs on a piezoelectric actuator substrate due to contact between individual electrodes and a liquid. The liquid discharge head 2 includes a head body 2a that includes a flow channel member 4 and a piezoelectric actuator substrate 21 having a plurality of individual electrodes 25, a flexible wiring substrate 92, and an adhesive member 60 that adheres the flexible wiring substrate 92 and the head body 2a and surrounds the individual electrodes 25. When a surface of the head body 2a surrounded by the adhesive member 60 is taken as a first region E2, and a surface of the head body 2a other than the first region E2 is taken as a second region E3, the head body 2a has a first through hole 7 connecting the first region E2 and the second region E3. The first through hole 7 permits communication between a space S1 surrounded by the flexible wiring substrate 92, the adhesive member 60, and the first region E1, and an outside other than the space S1.