Liquid Ejecting Head Case Member Wall Enclosure Bending
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Solution Overview
Problem
Ink jet type recording heads and other liquid ejecting heads face issues with ink leakage due to bending and distortion of case members and head chips, leading to adhesive strength challenges and increased risk of ink leakage during operation.
Innovation Solution
A liquid ejecting head design featuring a case member with a wall-shaped enclosure and a cover member fixed through integral molding, which creates a predetermined space to house the head chip, preventing external forces and minimizing the risk of ink leakage by using a flexible adhesive for fixation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If members are directly fixed to the case member using adhesive, then assembly is simplified, but adhesive strength is insufficient and ink leakage occurs due to bending and distortion
Solution Approach 1:
The case member is divided into a body portion and a protruding portion that extends into the predetermined space. The protruding portion acts as a separate structural element that provides additional support and anchoring for the head chip, separating the functions of containment (body portion) and structural reinforcement (protruding portion). This segmentation allows the adhesive to bond to both surfaces, effectively doubling the bonding area and strength without complicating the assembly process.
Solution Approach 2:
The protruding portion extends in the depth dimension into the predetermined space, creating a three-dimensional bonding structure rather than a simple two-dimensional surface bond. This dimensional extension provides the adhesive with additional bonding surfaces and creates a mechanical interlock that resists peeling forces from bending and distortion, significantly enhancing adhesive strength while maintaining assembly simplicity.
2Volume of moving object
If head chip size is reduced, then device miniaturization is achieved, but adhesive strength between members becomes insufficient
Solution Approach 1:
The case member is segmented into a body portion and a protruding portion, creating multiple bonding surfaces for the adhesive. This segmentation compensates for the reduced head chip size by providing additional bonding area through the protruding portion, ensuring sufficient adhesive strength is maintained even as the overall device is miniaturized.
Solution Approach 2:
The protruding portion extends into the depth dimension, creating a three-dimensional bonding structure that provides enhanced adhesive strength. This dimensional approach allows the bonding strength to be increased without increasing the planar footprint of the head chip, enabling miniaturization while maintaining structural integrity.
3Adaptability or versatility
If case member is bent during operation, then flexibility is achieved, but peeling force on fixed members increases causing ink leakage
Solution Approach 1:
The case member is segmented into a flexible body portion and a reinforcing protruding portion. This segmentation allows the body to maintain flexibility for adaptability while the protruding portion provides structural support to resist peeling forces during bending, preventing ink leakage without sacrificing the necessary flexibility.
Solution Approach 2:
The protruding portion acts as a preemptive structural reinforcement that cushions against the harmful peeling forces generated during bending. By providing this additional structural support in advance, the design prevents the adhesive bonds from failing under stress, thereby preventing ink leakage before it can occur during operation.
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 effectively suppresses ink leakage by preventing bending and external forces on the head chip and case member, ensuring reliable operation and maintaining adhesive strength even with smaller head chip sizes.
Implementation Method 1
a piezoelectric actuator which is disposed to face the pressure generation chamber. A pressure change is generated in the pressure generation chamber by a displacement of the piezoelectric actuator so that the ink drops are ejected from the nozzle
Data Source
AI summary
A wall-shaped enclosure that forms a space which can accommodate a head chip is formed in a projecting manner at a lower end of a lower case member. Since a cylindrical thick part is formed at the lower end of the lower case member, the lower case member is unlikely to be bent, particularly around the wall-shaped enclosure and a part where the wall-shaped enclosure is disposed. The head chip that is disposed in the space of the lower case member which is unlikely to be bent is unlikely to be subjected to an external force, and the cover member absorbs torsion generated between the head chip and the lower case member so that the head chip is even more unlikely to be subjected to the external force.