Liquid Ejection Head Electrode Layout Against Ink Erosion
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Solution Overview
Problem
In liquid ejection heads with independent drive structures, the erosion of common electrodes due to ink components can lead to disconnection of electrodes and increased resistance, causing variations in drive waveforms and deteriorating print quality such as dot diameter and linearity.
Innovation Solution
A liquid ejection head design featuring a common electrode that is formed on multiple surfaces of the substrate, including the front, back, and inner sidewalls, with individual electrodes covered by a coating layer to prevent erosion and maintain consistent drive waveforms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a common electrode is formed on the back surface of the substrate to enable independent drive structure, then liquid ejection speed is improved, but the electrode is eroded by ink components causing disconnection and resistance increase
Solution Approach 1:
The common electrode is extended from a single-plane configuration to a multi-dimensional configuration that includes the front surface, back surface, and side surfaces of the substrate. This spatial extension ensures that at least one portion of the common electrode remains in contact with the liquid supply hole, providing redundant electrical pathways and preventing complete disconnection even when other portions are eroded by ink components.
Solution Approach 2:
Different portions of the common electrode are strategically positioned in different locations (front surface, back surface, side surfaces) with varying exposure to ink. The electrode portions contact with the liquid supply hole are protected from erosion, while other portions may be exposed but serve as redundant pathways, creating localized functional zones within the electrode structure.
2Reliability
If the common electrode is formed on multiple surfaces including contact with liquid supply hole, then electrode erosion is prevented, but device complexity increases
Solution Approach 1:
The common electrode structure serves multiple functions simultaneously: it provides electrical connection to all pressure chambers, acts as a reference electrode for the drive circuit, and forms a protective configuration that prevents erosion by ink components. By making the electrode structure multi-functional, the patent avoids the need for separate protective structures, thereby managing complexity while achieving 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 design ensures high print quality by preventing electrode disconnection and resistance variations, ensuring uniform ink ejection and improved print quality.
Implementation Method 1
a coating layer to cover at least a part of the first surface of the substrate
Data Source
AI summary
According to one embodiment, a liquid ejection head includes a substrate and an actuator on a first surface side of the substrate. The actuator has pressure chambers and air chambers. Each pressure chamber is connected to an opening in the substrate extending from a second surface side of the substrate to the pressure chamber. A manifold is on the second surface side of the substrate and connected to the opening in the substrate. A common electrode includes a portion on the actuator, a portion on a surface of the substrate, a portion on another surface of the substrate, a portion on a sidewall surface of the opening, and a portion on a side surface of the substrate. Individual electrodes each have a portion on a surface of the actuator and a portion on a surface of the substrate.