Flexible Board Wiring Overlap for Low-Noise Liquid Jet Heads

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Solution Overview

Problem

Existing liquid jet recording devices face challenges in improving the reliability of liquid jet heads due to issues with drive noise, inductance components, and increased rigidity affecting the flexibility and handling of flexible boards.

Innovation Solution

The flexible boards are designed with overlapping regions of individual and common wiring layers, ensuring the common wiring lines are adjacent to individual wiring lines, reducing inductance components, and maintaining flexibility while enhancing electrical stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the common wiring line is arranged on the flexible board, then the liquid jet head can be driven, but the flexible board becomes rigid and handling becomes difficult

Engineering Contradiction:
Improvedriving capabilityVSAvoidhandling ease
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The patent uses a flexible board with a thin film structure that can bend and flex. The wiring layers are integrated into this flexible substrate, allowing the board to maintain its flexibility while providing necessary electrical connections for driving the liquid jet head.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The patent arranges wiring layers in multiple dimensions - individual wiring lines and common wiring lines are positioned in different layers and spatial relationships. This multi-dimensional arrangement reduces inductance by optimizing the geometric configuration of current paths without compromising flexibility.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Ease of operation

If the common wiring line is arranged away from individual wiring lines, then the flexible board remains flexible, but inductance increases and drive noise occurs

Engineering Contradiction:
ImproveflexibilityVSAvoidinductance and drive noise
Core Design Contradiction:
Ease of operationVSObject-generated harmful factors

Solution Approach 1:

The patent applies different wiring arrangements in different regions of the flexible board. In regions where individual wiring lines are present, common wiring lines are positioned adjacent to them to reduce inductance. In other regions, the wiring arrangement is optimized for flexibility. This localized optimization resolves the contradiction between flexibility and noise reduction.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent converts the potential harm of close wiring arrangement (which could increase capacitance) into a benefit by carefully controlling the geometry and spacing. The adjacent arrangement of individual and common wiring lines reduces inductance and drive noise while the flexible substrate design prevents excessive capacitance, turning a potential problem into a solution.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

Data Source

PatentEP4378692B1Flexible board, liquid jet head, and liquid jet recording device
Publication Date: 2025.09.24 SII PRINTEK INC
  • EP4378692B1 patent drawingFigure 1~2
  • EP4378692B1 patent drawingFigure 3
  • EP4378692B1 patent drawingFigure 4

AI summary

The flexible board according to an embodiment of the present disclosure includes a first wiring layer and a second wiring layer opposed to each other along a direction perpendicular to a board surface of the flexible board, at least one drive device which is arranged on the first wiring layer, and which is configured to generate a drive signal, an individual wiring region which is arranged in the first wiring layer, and which includes a plurality of individual wiring lines, a common wiring region which is arranged in the second wiring layer, and which includes at least one common wiring line, a pressure-bonding electrode part which is arranged closed to the jet section side than the individual wiring region and the common wiring region in the board surface, and which includes a plurality of pressure-bonding electrodes electrically coupled individually to the plurality of individual wiring lines and the at least one common wiring line, and an overlap region in which at least a part of the individual wiring region and at least a part of the common wiring region overlap each other in the board surface.