Liquid Ejection Head Electrode Layout for Low Resistance and Corrosion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High common electrode resistance in liquid ejection heads can lead to driver IC damage due to latch-up and increased heat generation, which is exacerbated by high ink ejection speeds, and the use of temperature control fluid paths can cause electrode corrosion.
Innovation Solution
The liquid ejection head design incorporates a multi-layered electrode structure for the common electrode, including Ni sputtered film, electroless Ni plated film, and electrolytic Au plated film, with specific configurations to minimize contact with temperature control fluids and reduce resistance, while maintaining effective voltage application to pressure chambers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the common electrode resistance is reduced by forming the electrode film on the back surface of the substrate, then the driver IC damage due to latch-up is prevented, but the electrodes may contact with the temperature control flow path and corrode due to electrolysis
Solution Approach 1:
The patent positions the common electrode on the back surface of the substrate, utilizing the z-dimension (thickness direction) to separate the electrode from the temperature control flow path. This spatial separation in the thickness direction prevents contact between the electrode and cooling fluid while still achieving low resistance through the extended electrode area on the back surface.
Solution Approach 2:
The substrate itself acts as an intermediary barrier between the common electrode and the temperature control flow path. By forming the electrode on the back surface, the substrate thickness serves as a physical separation layer that prevents direct contact between the electrode and cooling fluid, eliminating the electrolysis corrosion issue.
2Productivity
If the ink ejection speed is increased to improve productivity, then the printing efficiency is enhanced, but the heat generation in the head substrate is increased
Solution Approach 1:
The temperature control flow path acts as an intermediary heat dissipation system. By introducing cooling fluid that flows through the substrate, heat generated during high-speed ink ejection is efficiently removed, allowing sustained high productivity without excessive temperature rise.
Solution Approach 2:
The temperature control system utilizes phase change or heat absorption by the cooling fluid to remove excess heat from the substrate, enabling the system to maintain operational temperature even during high-speed ejection operations that generate significant heat.
3Reliability
If the common electrode area is increased to reduce resistance, then the driver IC protection is improved, but the contact area with temperature control fluid is increased leading to more corrosion
Solution Approach 1:
The patent resolves this contradiction by moving the electrode to the back surface of the substrate, utilizing the thickness dimension to create separation. This allows the electrode to have sufficient area for low resistance while being positioned in a location that does not contact the temperature control fluid, thus preventing corrosion.
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 design effectively reduces common electrode resistance, preventing driver IC damage and corrosion, while enabling efficient ink ejection and temperature control, thereby enhancing the reliability and performance of the liquid ejection head.
Implementation Method 1
Ni sputtered film
Implementation Method 2
electroless Ni plated film
Implementation Method 3
electrolytic Au plated film
Implementation Method 4
a vibrating plate at which is formed a piezoelectric element which deforms when voltage is applied
Implementation Method 5
the integrated circuit die is cooled by a coolant contacting the integrated circuit die and flowing through the substrate
Implementation Method 6
the electrode film is formed on the back surface of the substrate
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
According to one embodiment, a liquid ejection head includes a substrate with an opening through which a first liquid can pass. An actuator is on a first side of the substrate and has a plurality of pressure chambers. A manifold is on a second side of the substrate. The manifold forms a first flow path for a second fluid. The liquid ejection head has first electrode with portions formed on an upper surface of the actuator, a surface on the first side of the substrate, an inner wall of the opening, and a surface on the second side of the substrate in a region outside the first flow path.