Liquid Ejection Head Nozzle Positioning for Bubble Discharge
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Solution Overview
Problem
Ink ejection heads experience failures due to air bubbles adhering to the inner wall surfaces of nozzles, as the low flow velocity in specific regions of the liquid flow path prevents effective discharge of these bubbles, leading to pressure absorption and ink ejection failures.
Innovation Solution
A liquid ejection head design featuring a pressure chamber, descender, and communication passage, where the nozzle is positioned to maximize flow velocity by ensuring the shortest distance between its outer periphery and the center of the descender's end is greater than 0.5 times the second dimension, facilitating efficient liquid flow and bubble discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the nozzle is positioned at the region where liquid flow changes direction, then the structure is simple, but the flow velocity is low and air bubbles cannot be discharged
Solution Approach 1:
The patent applies local quality by positioning the nozzle at a specific location where the flow path has unique characteristics. The nozzle is placed at a distance greater than 0.5 times the second dimension from the center of the descender's end, creating a local region with high flow velocity that is optimal for bubble discharge. This localized positioning solves the contradiction by finding a specific spot that maintains structural simplicity while achieving the desired flow velocity.
2Device complexity
If the nozzle is positioned where liquid flow changes direction, then the structural arrangement is simplified, but air bubbles adhere to the nozzle and cause ejection failures
Solution Approach 1:
The patent applies parameter changes by modifying the positional parameter of the nozzle relative to the descender. Specifically, the distance between the nozzle outer periphery and the center of the descender's end is set to greater than 0.5 times the second dimension. This parameter change transforms the flow characteristics at the nozzle location, enabling effective bubble discharge and improving ejection reliability while maintaining simplified structural arrangement.
3Volume of moving object
If the nozzle is positioned close to the descender center, then the structure is compact, but flow velocity is insufficient to discharge air bubbles
Solution Approach 1:
The patent resolves this contradiction by applying local quality through precise nozzle positioning. Rather than uniformly distributing components, the nozzle is strategically placed at a specific distance (greater than 0.5 times the second dimension) from the descender center. This creates a localized high-velocity flow region that maintains compact overall structure while achieving sufficient flow velocity for bubble discharge at the nozzle location.
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 enhances the ejection head's ability to rapidly discharge air bubbles, reducing ejection failures by maintaining high flow velocity and efficiently guiding liquid through the system, thereby improving the reliability of ink ejection.
Implementation Method 1
Liquid flows in the individual liquid chamber in a first direction, and liquid flows in the circulation channel in a second direction crossing the first direction
Data Source
AI summary
In a liquid ejection head, an ejection pressure is applied to a pressure chamber for liquid ejection from a nozzle. A descender extends in a first direction and includes a first end connected to the pressure chamber and a second end. A communication passage is connected to the second end, extends in a second direction crossing the first direction, and has a first dimension in the first direction. The nozzle is positioned at the communication passage such that a shortest distance between an outer periphery thereof and a center of the second end is greater than 0.5 times a second dimension of the second end in the second direction. When viewed in the first direction, the center of the second end and a center of a cross-section defined by the nozzle to be orthogonal to an extending direction of the nozzle intersect an axis of the communication passage.