Electrowetting Liquid Transfer Device for Compact Inkjet Heads
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Solution Overview
Problem
Conventional inkjet heads have complex constructions that increase manufacturing costs and make it difficult to densely pack nozzles and pressure chambers, limiting the reduction in size of the device.
Innovation Solution
A liquid transfer device with a simple construction featuring insulating regions, neighboring regions with varying liquid-repellent properties, and electrodes that control potential differences to manage liquid flow by opening or closing the flow passage through electro-wetting phenomena, allowing pressurized liquid to be transferred efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional inkjet head construction with separate passage unit and actuator unit is used, then reliable ink ejection is achieved, but device complexity increases and manufacturing cost rises
Solution Approach 1:
The patent merges the passage unit and actuator unit into a single integrated structure where the piezoelectric layer is formed directly on the flow passage defining face. This eliminates the need for separate actuator units and complex bonding interfaces, reducing device complexity while maintaining reliable ink ejection through the integrated pressure application mechanism.
Solution Approach 2:
The flow passage defining face serves multiple functions: it defines the ink flow passages, provides the surface for piezoelectric layer formation, and acts as the actuation surface. This multi-functionality reduces the number of separate components needed, simplifying the overall construction while preserving the reliability of ink ejection.
2Productivity
If multiple individual ink flow passages with pressure chambers are formed densely, then nozzle density increases, but each pressure chamber requires minimum volume making dense formation difficult
Solution Approach 1:
The patent extracts the pressure chamber concept from the traditional design and replaces it with a piezoelectrically-actuated flow passage system. By applying pressure directly through the piezoelectric layer on the flow passage defining face, the need for large-volume pressure chambers is eliminated, enabling much higher nozzle density while maintaining effective ink ejection.
Solution Approach 2:
The patent changes the operating parameters of the flow passage system by using piezoelectric actuation to generate the necessary pressure dynamically, rather than relying on fixed-volume pressure chambers. This allows the flow passages to be made much smaller and more numerous, increasing nozzle density while maintaining the required pressure for ink ejection through electrical actuation.
3Ease of operation
If piezoelectric actuator unit with multiple individual electrodes and common electrode is used, then precise ink ejection control is achieved, but manufacturing cost increases
Solution Approach 1:
The patent merges the electrode structure directly into the flow passage defining face, eliminating the need for separate actuator units with multiple electrodes. The piezoelectric layer is formed directly on the flow passage defining face, reducing the number of components and assembly steps, thereby lowering manufacturing cost while maintaining precise ink ejection control through the integrated structure.
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 enables a cost-effective and compact liquid transfer device that can efficiently open and close ink flow passages, reducing manufacturing costs and allowing for a more compact design while ensuring reliable ink transfer.
Implementation Method 1
a piezoelectric layer made of lead zirconate titanate (PZT), sandwiched by the individual electrodes and the common electrode. When the electric potential of an individual electrode is controlled to be different from that of the common electrode, an electric field is applied to the portion of the piezoelectric layer sandwiched by the individual electrode and the common electrode and thereby the piezoelectric layer is partially deformed.
Implementation Method 2
a liquid flow passage defined by one or more flow passage defining faces, the liquid flow passage comprising insulating regions and a first neighboring region formed on at least one of the flow passage defining faces, the first neighboring region being lower in liquid-repellent than the insulating regions... an opening/closing controller that controls potentials of the first and second electrodes to change over the liquid flow passage
Data Source
AI summary
A liquid transfer device includes therein a liquid flow passage in which an insulating region and a neighboring region lower in liquid-repellent than the insulating region and neighboring the insulating region in the direction of flow of liquid, are formed on a flow passage defining face. A first electrode is covered with a flow passage area provided in the insulating region so as to neighbor the neighboring region and extend over the whole length of the insulating region in the direction of flow of liquid. A second electrode is covered with a first bubble hold area provided in the insulating region so as to neighbor the neighboring region. By controlling the potentials of the first and second electrodes, the liquid flow passage is changed over between a first state wherein liquid can be transferred on the flow passage area, and a second state wherein the liquid flow passage is closed by a meniscus formed such that the flow passage area is covered with no liquid.