Liquid Ejection Head Mold Asymmetry for Partition Wall Thickness
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Solution Overview
Problem
The existing manufacturing methods for liquid ejection heads face challenges in maintaining even thickness of partition walls between liquid chambers, leading to issues like sink and short circuit during molding, especially as the number of ejection ports increases, requiring larger liquid chambers to accommodate air bubbles and ink, which complicates the molding process.
Innovation Solution
The method involves arranging mold pieces with decreasing widths in opposite directions to form liquid chambers, ensuring that the partition walls have a constant thickness in the cross direction, preventing unevenness and related manufacturing defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of ejection ports is increased to increase recording rate, then the recordable width is improved, but the volume of liquid chambers needs to be increased to accommodate more liquid and air bubbles
Solution Approach 1:
The liquid chambers are elongated in the cross direction (width direction) rather than extending in the scanning direction. This dimensional reorientation allows the chambers to accommodate increased liquid volume and air bubbles while maintaining a compact form factor in the scanning direction, thus supporting higher ejection port counts without proportionally increasing overall head size.
2Ease of manufacture
If mold pieces are drawn in the same direction with draft for ease of molding, then the ease of manufacture is improved, but the thickness of partition walls becomes uneven leading to sink and short circuit defects
Solution Approach 1:
Adjacent mold pieces are drawn in opposite directions rather than the same direction. This asymmetric drawing approach creates mirror-image draft angles on either side of each partition wall, which compensates for the thickness variation that would otherwise occur. The opposing drafts balance each other out, maintaining uniform partition wall thickness while still allowing each mold piece to be drawn for ease of manufacture.
3Volume of stationary object
If liquid chambers are elongated in the cross direction to accommodate air bubbles, then the capacity to accumulate air bubbles is improved, but the mold pieces become elongated making thickness uniformity more difficult to maintain
Solution Approach 1:
By drawing adjacent mold pieces in opposite directions, the invention creates a balancing effect where the draft-induced thickness variations on one side of a partition wall are compensated by the opposing draft on the other side. This allows the mold pieces to be elongated in the cross direction to provide sufficient chamber capacity while maintaining uniform partition wall thickness through the asymmetric drawing configuration.
Data Source
AI summary
A liquid ejection head has a plurality of ejection ports for ejecting a liquid, and a housing provided with a pair of liquid chambers which supply the liquid to a corresponding ejection port. A method for manufacturing the liquid ejection head includes: arranging a pair of mold pieces, of which width decreases gradually, to adjoin in the width direction thereof with the width decreasing in the opposite directions, molding a housing, and forming the pair of liquid chambers by drawing the pair of mold pieces from the molded housing in the direction in which the width increases.