Liquid Ejection Head Substrate Heating Unit Design
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Solution Overview
Problem
Temperature distribution in print head substrates leads to uneven ink ejection, causing image quality deterioration, and existing solutions increase the substrate area and print head size by widening the sub heater, limiting design flexibility.
Innovation Solution
A liquid ejection head substrate with a heating unit comprising a heating element and wiring spaced orthogonally, connected by bypass portions, allowing current to flow through the wiring when the heating element is energized, reducing the overall resistance and area of the sub heater while maintaining desired heating values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the width of the sub heater is increased to reduce electric resistance and raise heating value, then the heating value is improved, but the substrate area and print head size increase
Solution Approach 1:
The patent introduces a vertical dimension by positioning the sub heater and wiring in layers above and below the substrate surface, respectively. This three-dimensional arrangement allows current to flow through the wiring in parallel with the sub heater, reducing the effective resistance without increasing the substrate area. The wiring is spaced apart from the sub heater in the vertical direction, creating a layered structure that maintains compact footprint while improving heating efficiency.
Solution Approach 2:
The wiring acts as an intermediary element that provides an additional current path. By positioning the wiring between the sub heater and the substrate, the system creates a parallel circuit where current can flow through both the sub heater and the wiring. This intermediary structure reduces the overall resistance without requiring the sub heater to occupy more area, as the wiring shares the current load.
2Power
If the area of the sub heater is increased to reduce electric resistance, then the heating value is improved, but the degree of freedom in sub heater arrangement is reduced
Solution Approach 1:
The patent resolves the arrangement flexibility issue by utilizing the vertical dimension. The sub heater and wiring are positioned in separate layers above and below the substrate, allowing independent optimization of their positions. This layered structure maintains design flexibility because the wiring can be routed in various patterns to achieve desired heating characteristics without being constrained by a large sub heater area.
Solution Approach 2:
The system segments the current path into two distinct components: the sub heater for primary heating and the wiring for supplementary current conduction. This segmentation allows each component to be independently designed and positioned, maintaining adaptability in arrangement while achieving the desired heating value through the combined effect of both elements.
3Power
If the width of the sub heater is increased to minimize electric resistance, then the heating value is improved, but the size of the print head increases
Solution Approach 1:
The patent eliminates the need to increase print head size by utilizing the vertical dimension for current path expansion. The wiring is positioned in a layer below the substrate, creating a three-dimensional current pathway that reduces resistance without adding lateral dimensions. This maintains a compact print head footprint while achieving improved heating value through the additional current path provided by the wiring.
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 configuration effectively heats ink to a desired value with reduced substrate area and print head size, enhancing design flexibility and improving image quality by uniform temperature distribution.
Implementation Method 1
a heating element extending in a direction of the element array and generating heat by being energized
Implementation Method 2
An ejection energy generating element for ink ejection is provided for each of the plurality of ejection ports of the print head substrate, and ink in the ejection port is ejected in the form of droplets by the ejection energy generating element being driven
Data Source
AI summary
A liquid ejection head substrate has heating unit and an element array in which a plurality of ejection energy generating elements generating ejection energy for liquid ejection are arranged on a surface side of a base material. The heating unit includes a heating element extending in a direction of the element array and generating heat by being energized, wiring spaced apart from the heating element in a direction orthogonal to the surface of the base material, and a plurality of connecting portions connecting the heating element and the wiring to each other. The heating element, the wiring, and the plurality of connecting portions are provided in a region overlapping a region where the element array is disposed in a direction orthogonal to the direction of the element array when seen from the direction orthogonal to the surface of the base material. A current flows to the wiring in a middle of a path of the current flowing through the heating element when the heating element is energized.