Inkjet Head Electrical Connection via Cavity and Conductive Paste

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Solution Overview

Problem

The existing inkjet head technologies face issues with maintaining a reliable electrical connection between the flow channel unit and the common electrode of the actuator unit, leading to potential damage due to hydrogen ion migration and adhesive leakage, which can clog ink channels.

Innovation Solution

The inkjet head design incorporates a contact terminal exposed on the attachment surface of the actuator unit, with a cavity on the flow channel unit filled with a conductive material to establish a secure electrical connection without the need for scraping off adhesive, preventing hydrogen ion migration and channel clogging.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conductive adhesive is applied on the side end face of the actuator unit to electrically connect the common electrode to the flow channel unit, then electrical connection is established, but adhesive may leak onto the upper surface of the flow channel unit causing channel clogging

Engineering Contradiction:

Improveelectrical connection reliabilityVSAvoidadhesive leakage causing channel clogging

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent divides the electrical connection function from the adhesive application area. A cavity is formed on the flow channel unit, and conductive paste is applied only within this cavity, separating the electrical connection zone from the adhesive application zone. This prevents adhesive from leaking onto the upper surface and clogging channels while maintaining reliable electrical connection.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The cavity acts as an intermediary structure that contains the conductive paste and prevents adhesive from migrating into the ink discharge path. The conductive paste serves as an intermediary material that provides electrical connection without requiring adhesive to be applied in the ink discharge area.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Strength

If adhesive is applied to fix the actuator unit to the flow channel unit, then mechanical attachment is achieved, but adhesive may cover the upper surface preventing electrical connection

Engineering Contradiction:

Improvemechanical attachment strengthVSAvoidelectrical connection reliability

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The patent segments the attachment surface into two functional zones: a cavity area for electrical connection and an adhesive application area for mechanical attachment. The cavity is positioned such that adhesive applied for mechanical bonding does not interfere with the electrical connection area, allowing both functions to be performed simultaneously without interference.

Inventive Principle:

Principle #1Segmentation

3Object-affected harmful factors

If the common electrode is electrically connected to the flow channel unit, then hydrogen ion migration is prevented, but adhesive leakage may clog ink channels

Engineering Contradiction:

Improvehydrogen ion migration preventionVSAvoidadhesive leakage causing channel clogging

Core Design Contradiction:

Object-affected harmful factorsVSObject-generated harmful factors

Solution Approach 1:

The patent creates a clear separation between the electrical connection function (achieved through conductive paste in the cavity) and the mechanical attachment function (achieved through adhesive). This segmentation ensures that adhesive does not leak into the ink discharge path while the electrical connection is maintained, preventing both hydrogen ion migration and channel clogging.

Inventive Principle:

Principle #1Segmentation

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 configuration ensures a reliable and adhesive-free electrical connection between the flow channel unit and the common electrode, preventing damage and maintaining ink channel integrity.

Implementation Method 1

The cavity is filled with a conductive material, and the conductive material electrically connects the contact terminal of the actuator unit with the flow channel unit

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 2

The actuator unit includes a piezoelectric sheet, a common electrode and a plurality of individual electrodes

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentUS7581825B2Inkjet head and a method of manufacturing thereof

Publication Date: 2009.09.01 BROTHER KOGYO KK

AI summary

To provide an inkjet head that maintains a reliable electric connection between a flow channel unit and a common electrode of an actuator unit, a flow channel unit is provided with a cavity formed on an attachment surface of flow channel unit to attach to an actuator unit, and the actuator unit is provided with a contact terminal connected to the common electrode and formed at a position facing the cavity when the flow channel unit and the actuator unit are attached. The common electrode is reliably connected to the flow channel unit through the contact terminal and a conductive material filling the cavity.