Liquid Ejection Head Curved Protrusion for Membrane Crack Prevention
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Solution Overview
Problem
The existing manufacturing methods for liquid ejection heads face challenges in ensuring a sufficient area for the supply path opening portion while preventing cracks in the membrane film, which can lead to reliability issues and closure of the supply path opening portion.
Innovation Solution
The liquid ejection head features a flow path forming member with a structure protruding from the substrate towards the supply path, having a curved surface peripheral shape at the distal end portion, which reduces the bending angle of the membrane film and suppresses stress concentration, thereby preventing cracks and ensuring a sufficient supply path area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a structure protruding toward the supply path is added to support the membrane film, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The distal end portion of the protruding structure is designed with a curved surface shape instead of a sharp corner. This curvature reduces stress concentration at the tip of the protrusion, preventing membrane film cracks while maintaining structural support. The curved surface distributes mechanical stress more evenly, solving the contradiction between providing sufficient support and avoiding stress-induced failures.
Solution Approach 2:
The protruding structure is strategically positioned only where membrane film support is needed, rather than uniformly across the entire flow path forming member. This localized approach provides necessary support to prevent cracks in critical areas while minimizing overall structural complexity and material usage.
2Productivity
If the supply path opening portion area is increased, then the productivity is improved, but the manufacturing precision deteriorates due to difficulty in preventing membrane film cracks
Solution Approach 1:
The curved surface at the distal end of the protruding structure eliminates stress concentration points that would otherwise cause membrane film cracks. This allows the supply path opening portion to be made larger without compromising manufacturing precision, as the curved geometry prevents crack initiation even in larger opening areas where membrane film stress would otherwise be higher.
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 design effectively prevents cracks in the membrane film and maintains a sufficient area for the supply path opening portion, enhancing the reliability and functionality of the liquid ejection head.
Implementation Method 1
a silicon oxide film or a silicon nitride film formed on a surface of the silicon substrate is used as an etching stop layer
Implementation Method 2
a peripheral shape of a distal end portion of the structure is a curved surface shape
Data Source
AI summary
A liquid ejection head including a substrate, an energy generating element provided on the substrate, a film provided on the substrate and the energy generating element, and a flow path forming member provided on the substrate, forming a flow path of a liquid between the flow path forming member and the substrate, and having an ejection orifice at a position faced with the energy generating element, characterized in that the substrate has a supply path of the liquid communicating with the flow path, the flow path forming member has a structure protruding toward the supply path, and a peripheral shape of a distal end portion of the structure is a curved surface shape.