Liquid Ejection Head Cavity Layout for Near-Infrared Inspection
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Solution Overview
Problem
Conventional liquid ejection heads with enclosed cavities hinder effective near-infrared light inspection due to light scattering from inclined side surfaces and curved bottom surfaces, preventing thorough inspection of energy generating elements and their connections.
Innovation Solution
The design of the liquid ejection head includes recessed portions with side surfaces and bottom surfaces that are inclined to minimize light scattering, allowing for effective near-infrared light inspection by ensuring that the energy generating elements and their connections can be clearly observed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the enclosed cavity has a folding-fan shape that widens toward the ejection port, then the energy generating element can be properly housed, but near-infrared light scatters in the folding-fan portion preventing sufficient reflected light from reaching the microscope
Solution Approach 1:
The patent inverts the conventional folding-fan shape by making the enclosed cavity narrow at the ejection port side and wide at the substrate joint side. This inversion reverses the light scattering problem, allowing near-infrared light to reflect effectively from the energy generating element to the microscope while still accommodating the component properly
Solution Approach 2:
The patent changes the geometric parameters of the enclosed cavity, specifically the angle and orientation of the side surfaces. By adjusting these parameters, the cavity shape is optimized to minimize light scattering in the near-infrared range while maintaining functional requirements for housing the energy generating element
2Shape
If the side surfaces of the recessed portion are inclined, then the energy generating element can be housed, but light scattering occurs preventing proper inspection
Solution Approach 1:
The patent applies different surface orientations to different regions of the enclosed cavity. The side surface near the electrode is inclined at a specific angle to minimize scattering, while other portions may have different orientations optimized for their specific functions, creating localized optical quality variations
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
Enables comprehensive inspection of the energy generating elements and their connections using near-infrared light, providing accurate feedback for the manufacturing process and ensuring proper assembly.
Implementation Method 1
a near-infrared light microscope, which performs inspection by irradiation with near-infrared light
Implementation Method 2
An example of the energy generating element is a piezoelectric element
Data Source
AI summary
A liquid ejection head includes a first substrate having a recessed portion, and a second substrate. An energy generating element that generates energy to eject liquid is in the recessed portion and is placed on a surface of the second substrate that faces the recessed portion. An electrode electrically connected to the energy generating element is formed in an end portion of the energy generating element. Among recessed portion side surfaces, a side surface of the recessed portion close to the electrode is inclined with respect to a joint surface between the first substrate and the second substrate. The end portion of the energy generating element close to the electrode, an end portion of the joint surface close to the electrode, and an end portion of a bottom surface of the recessed portion close to the electrode are located in sequence from a middle of the energy generating element.