Liquid Ejecting Head Sealing with High Gas Barrier Member
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Solution Overview
Problem
Existing liquid ejecting heads suffer from liquid thickening due to moisture evaporation through seal members with inadequate gas barrier properties, leading to viscosity increase and reliability issues in inkjet printers and other applications.
Innovation Solution
A liquid ejecting head with a flow path member housed in a sealed space defined by a flow path-isolating member with higher gas barrier properties, preventing moisture evaporation and ensuring double-sealing of the connecting portions between case members, while allowing a resistance pathway for pressure equalization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a seal member made of common elastomer is used to provide liquid-tight communication, then liquid sealing is achieved, but moisture vapor passes through the seal member material causing liquid thickening
Solution Approach 1:
The patent segments the sealing function into two distinct components: a seal member for liquid-tight sealing and a flow path-isolating member for gas barrier protection. This segmentation allows each component to specialize in its respective function without compromise.
Solution Approach 2:
The flow path-isolating member acts as an intermediary between the liquid flow path and the atmosphere, providing a high gas barrier property layer that prevents moisture evaporation while allowing the seal member to focus on liquid sealing.
2Ease of manufacture
If the upper case member is merely fixed to the lower case member by screwing or crimping, then assembly is simple, but gas tightness and liquid tightness of the interior are not secured
Solution Approach 1:
The patent merges the case fixing function with the sealing function by integrating the flow path-isolating member into the case structure. This merging ensures that gas tightness and liquid tightness are secured while maintaining assembly simplicity through the unified design.
3Stress or pressure
If an atmospherically open path is provided through the seal member, then pressure equalization is achieved, but moisture vapor diffuses into the atmosphere causing liquid thickening
Solution Approach 1:
The patent applies local quality by providing different properties in different regions: the seal member region allows pressure equalization through atmospherically open paths, while the flow path-isolating member region provides high gas barrier properties to prevent moisture evaporation.
4Loss of substance
If a flow path-isolating member with higher gas barrier property is introduced, then moisture evaporation is prevented, but device complexity increases
Solution Approach 1:
The flow path-isolating member is designed to perform multiple functions: providing high gas barrier properties, maintaining structural integrity, and working in conjunction with the seal member. This multi-functionality reduces the need for additional components, thereby limiting the increase in device complexity.
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 solution effectively inhibits liquid thickening, maintaining consistent ink ejection characteristics and improving the reliability of the liquid ejecting apparatus by reducing moisture evaporation and pressure changes within the sealed space.
Implementation Method 1
moisture (a solvent component) in a liquid flow path passes in the form of vapor through the material of the seal member in addition to the foregoing atmospherically open path and diffuses into the atmosphere. Therefore, there is a problem that the thickening (viscosity increase) of the liquid in the liquid flow path of the flow path member in particular progresses.
Implementation Method 2
a seal member (bush) made of an elastic material is provided between a lower case member and a flow path portion that includes the upper case member and a flow path member. This seal member provides liquid-tight communication between a flow path of a flow path portion side and a flow path of a lower case member side via a through opening of the seal member.
Data Source
AI summary
A liquid ejecting head includes a first case that houses a flow path member that is provided with a liquid flow path, a second case that includes a head unit, a seal member that includes a connecting portion that seals and liquid-tightly connects the liquid flow path on a first case side and a liquid flow path on a second case side. The liquid ejecting head ejects a liquid supplied from the flow path member from a nozzle of the head unit. A flow path-isolating member having higher gas barrier property than the seal member is disposed between the first case and the seal member. The flow path member is disposed in a sealed space that is defined in the first case by a flow path-isolating member being joined to the first case.