Liquid Ejection Head Wiring Extraction for Bend Reliability
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Solution Overview
Problem
The increasing integration of energy generation elements in liquid ejection heads leads to a higher number of wires in flexible circuit boards, which can result in wiring breakage at bending portions due to insufficient bend curvature and increased size of the liquid ejection head.
Innovation Solution
The liquid ejection head is designed with a flexible circuit board that has a bending portion bent along one side of a support member, where the wiring is absent in a region facing the element substrate, allowing for improved electrical reliability and reduced bending curvature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the flexible circuit board is bent with a small bend curvature to reduce the size of the liquid ejection head, then the size of the liquid ejection head is reduced, but the wiring inside the flexible circuit board may be broken at the bending portion
Solution Approach 1:
The patent extracts the wiring from the bending portion of the flexible circuit board by creating an opening that excludes the wiring region from the bending area. This allows the flexible circuit board to be bent with small curvature while preventing wiring breakage, as the wiring is removed from the region subject to bending stress.
Solution Approach 2:
The flexible circuit board is segmented into distinct regions: a bending portion for flexibility and an opening region that excludes wiring. This segmentation allows the bending portion to be optimized for flexibility while the wiring is protected in a separate region, resolving the contradiction between small bend curvature and wiring reliability.
2Length of moving object
If the flexible circuit board is bent at a curvature close to a right angle to suppress increase in paper pressing width, then the paper pressing width is suppressed, but the wiring inside the flexible circuit board may be broken at the bending portion
Solution Approach 1:
The wiring is extracted from the bending portion by creating an opening that excludes the wiring region. This enables the flexible circuit board to be bent at a curvature close to a right angle to suppress paper pressing width increase, while the wiring is protected from breakage by being removed from the high-stress bending region.
3Quantity of substance
If the width and length of the flexible circuit board are increased to accommodate the increased number of wires, then the number of wires can be accommodated, but the size of the liquid ejection head increases
Solution Approach 1:
The patent utilizes the vertical dimension by creating an opening that extends in the thickness direction of the flexible circuit board. This allows the wiring to be routed through the opening, accommodating the increased number of wires without increasing the planar width and length of the flexible circuit board, thereby avoiding size increase of the liquid ejection head.
Data Source
AI summary
A liquid ejection head includes an element substrate configured to include an element, which is driven by a drive signal, and an ejection opening for ejecting liquid by driving of the element, a flexible circuit board configured to include wiring for supplying the drive signal to the element, and a support member configured to support the element substrate and the flexible circuit board via a surface of the support member, wherein the flexible circuit board has a bending portion bent along one side of the support member extending in a first direction, and wherein in the bending portion, the wiring is absent in a region facing a side of the element substrate in a second direction orthogonal to the first direction when viewed from a direction perpendicular to the surface of the support member.