Flexible Wiring Substrate Slits for Inkjet Head Resistance
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Solution Overview
Problem
Ink jet recording heads with multiple piezoelectric actuators face issues with increased electric resistance at connection points, leading to voltage drops and potential driving failures, as well as heat-related breakdowns due to enlarged conductive areas, which hinder the miniaturization and increased density of nozzle rows.
Innovation Solution
A liquid ejecting head design featuring a flexible wiring substrate with slits connected to a common electrode via an anisotropic conductive material, reducing electric resistance by increasing the number of conductive particles and allowing for uniform gap distribution, thus suppressing driving failures and heat-related issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the conductive connection area of the connection portion is enlarged to reduce electric resistance, then voltage drop is reduced and driving reliability is improved, but the liquid ejecting head becomes larger
Solution Approach 1:
The patent employs a flexible wiring substrate with a wiring layer that can be elastically deformed. By applying pressure to the connection portion, the wiring layer deforms to conform to the terminal portion surface, ensuring intimate contact and reducing electric resistance without requiring a large connection area. This flexible film approach allows reliable electrical connection in a compact space.
Solution Approach 2:
The patent utilizes the curvature and three-dimensional surface topology of the terminal portion. The wiring layer is designed to conform to the curved or uneven surface of the terminal portion when pressed, maximizing the contact area between the wiring layer and terminal portion. This curvature-based contact optimization reduces electric resistance without increasing the overall connection area footprint.
2Reliability
If the conductive connection area of the connection portion is enlarged to reduce electric resistance, then voltage drop is reduced, but heat generation increases causing wiring substrate breakdown
Solution Approach 1:
The flexible wiring substrate with its deformable wiring layer creates intimate contact with the terminal portion, reducing contact resistance and thereby reducing heat generation at the connection interface. The elastic deformation ensures consistent pressure contact, maintaining low resistance and minimizing thermal buildup that could lead to substrate breakdown.
Solution Approach 2:
The patent changes the physical state and contact parameters of the wiring layer by applying pressure-induced elastic deformation. This dynamic adjustment of contact pressure and contact area optimizes the electrical connection properties, reducing both electric resistance and the associated heat generation that would otherwise threaten substrate integrity.
3Productivity
If the number and density of nozzle rows are increased to improve productivity, then more piezoelectric actuators are required, but electric resistance at connection portions increases causing voltage drop
Solution Approach 1:
The flexible wiring substrate with elastically deformable wiring layer provides consistent, low-resistance electrical connections to multiple piezoelectric actuators. The pressure-induced deformation ensures intimate contact across all connection points, maintaining reliable voltage delivery even as the number of actuators and nozzle rows increases, thus supporting higher productivity without sacrificing driving reliability.
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 reduces electric resistance, preventing driving failures and heat-induced breakdowns, enabling the miniaturization and increased density of nozzle rows while maintaining efficient ink droplet discharge.
Implementation Method 1
the wiring layer of the wiring substrate and the terminal portion of the pressure generation unit be connected via an anisotropic conductive material
Implementation Method 2
connected via an anisotropic conductive material
Implementation Method 3
a vibration plate, the vibration plate is deformed by the piezoelectric actuator as a piezoelectric element to pressurize ink in the pressure generation chamber
Data Source
AI summary
A liquid ejecting head includes: a pressure generation chamber that communicates with a nozzle opening which ejects liquid; a pressure generation unit that causes a change in pressure in the pressure generation chamber; and a flexible wiring substrate that transmits a control signal from outside and includes a wiring layer which is connected to each individual electrode of a plurality of pressure generation units and also connected to a terminal portion of a common electrode common to the plurality of pressure generation units. In the liquid ejecting head, the wiring layer of the wiring substrate includes slits in an area connected to the terminal portion of the common electrode of the pressure generation unit, while the wiring layer of the wiring substrate and the terminal portion of the pressure generation unit are connected via an anisotropic conductive material.