Liquid Ejection Head Inverted Electrical Connections

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Solution Overview

Problem

Existing liquid ejection heads with heat generating resistor elements face issues of increased power consumption due to thick protective films and the formation of non-heat generating regions, which lead to stagnant ink and bubble pool formation, affecting ejection performance.

Innovation Solution

The liquid ejection head design features electrical connection regions on the substrate-facing surface of heat generating resistor elements, minimizing non-heat generating regions and using oblique or curved corner profiles to reduce stagnation, thereby enhancing thermal conductivity and ejection efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If electrical connection regions are arranged on the bubble forming chamber-facing surface, then electrical connection reliability is improved, but protective film thickness must be increased and power consumption rises

Engineering Contradiction:

Improveelectrical connection reliabilityVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent inverts the conventional arrangement by placing electrical connection regions on the substrate-facing surface instead of the bubble forming chamber-facing surface. This inversion eliminates the need for thick protective films while maintaining electrical connection reliability through direct plug contact with the inverted connection regions.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent changes the spatial dimension of electrical connection regions from the top surface (bubble forming chamber-facing) to the bottom surface (substrate-facing) of the heat generating resistor element, allowing electrical connections to be established without interfering with the bubble formation process and reducing protective film requirements.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Reliability

If electrical connection regions are positioned away from peripheral edges, then electrical connection reliability is improved, but non-heat generating regions increase and bubble pools form

Engineering Contradiction:

Improveelectrical connection reliabilityVSAvoidliquid ejection performance

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

By inverting the electrical connection regions to the substrate-facing surface, the patent allows connection regions to extend to the peripheral edges of the heat generating resistor element without compromising connection reliability. This eliminates non-heat generating regions at the edges and prevents bubble pool formation while maintaining reliable electrical connections.

Inventive Principle:

Principle #13The other way round (Inversion)

3Reliability

If protective film thickness is increased, then electrical connection reliability is improved, but thermal conductivity decreases and power consumption increases

Engineering Contradiction:

Improveelectrical connection reliabilityVSAvoidthermal conductivity

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The patent inverts the electrical connection arrangement to the substrate-facing surface, which eliminates the need for thick protective films. This allows thermal energy to be efficiently conducted from the heat generating resistor element to the liquid in the bubble forming chamber while maintaining reliable electrical connections through direct plug contact.

Inventive Principle:

Principle #13The other way round (Inversion)

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 design reduces power consumption and minimizes bubble pool formation, improving ink ejection capacity and speed by optimizing the arrangement of electrical connections and corner profiles.

Implementation Method 1

heat generating resistor elements arranged on the substrate to generate thermal energy for ejecting liquid

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Data Source

PatentEP3412462B1Liquid ejection head

Publication Date: 2020.12.23 CANON KK

Figure 1
Figure 2A~2B
Figure 3

AI summary

A liquid ejection head includes a substrate, a heat generating resistor element arranged on the substrate and a flow channel forming member for forming a flow channel. The flow channel forming member has a side wall surrounding at least part of the heat generating resistor element. The heat generating resistor element has a pair of oppositely disposed sides and a pair of electrical connection regions which extend along the respective ones of the pair of sides and are separated from the respective ones of the pair of sides by a distance. The side wall has at least one concave corner which is comprised of a curved surface or a surface extending obliquely to the pair of sides and the heat generating resistor element has at least one convex corner which faces the at least one concave corner of the side wall and is rounded or chamfered.