Liquid Ejecting Head Screw Arrangement for Stiffness Mismatch

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Solution Overview

Problem

The existing liquid ejecting head designs face issues with deformation of the main body part due to uneven stiffness, leading to inaccurate ink ejection, and increasing the number of screws to address this problem increases costs and reduces productivity.

Innovation Solution

The liquid ejecting head employs a strategic arrangement of screws on the sub-tank attachment, using more screws in low-stiffness areas and fewer in high-stiffness areas to distribute the reaction force effectively, thereby minimizing deformation and maintaining ejection accuracy while reducing the overall number of screws needed.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the number of screws is increased to fix the sub-tank, then the main body part conforms better to the sub-tank and deformation is reduced, but the cost and man-hour increase leading to decreased productivity

Engineering Contradiction:
Improveejection accuracyVSAvoidproductivity
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The patent applies different numbers of screws at different locations on the main body part based on local stiffness characteristics. Specifically, a first number of screws is used in a first region with certain stiffness, while a second number of screws (different from the first) is used in a second region with different stiffness. This local differentiation allows the structure to achieve adequate fixation and conformality without uniformly over-screwing the entire assembly, thereby maintaining ejection accuracy while improving productivity and reducing cost.

Inventive Principle:
Principle #3Local quality

2Manufacturing precision

If the number of screws is increased to fix the sub-tank, then the main body part conforms better to the sub-tank, but the cost increases

Engineering Contradiction:
Improveejection accuracyVSAvoidcost
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent implements a differentiated screw arrangement strategy where the number of screws varies by region based on local structural requirements. In regions with higher stiffness, fewer screws are needed, while regions with lower stiffness receive more screws. This localized approach ensures adequate conformality and ejection accuracy only where necessary, avoiding the waste of using excessive screws throughout the entire structure, thereby reducing material cost and assembly complexity.

Inventive Principle:
Principle #3Local quality

3Manufacturing precision

If the number of screws is increased to fix the sub-tank, then the main body part conforms better to the sub-tank, but the man-hour increases leading to decreased productivity

Engineering Contradiction:
Improveejection accuracyVSAvoidman-hour
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent employs a region-specific screw configuration where the quantity of screws is optimized for each local area based on stiffness characteristics. This means that instead of requiring a uniform high number of screws across the entire main body part, the design specifies different screw counts for different regions. Consequently, the assembly process requires fewer total screw installation operations, reducing man-hour and improving productivity while still achieving the necessary conformality and ejection accuracy in critical areas.

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP3936344B1Liquid ejecting head and liquid ejecting apparatus
Publication Date: 2024.03.27 CANON KK
  • EP3936344B1 patent drawingFigure 1
  • EP3936344B1 patent drawingFigure 2
  • EP3936344B1 patent drawingFigure 3

AI summary

Provided is a liquid ejecting head (5) and a liquid ejecting apparatus (1) that can suppress decrease in ejection accuracy while suppressing increase in cost and decrease in productivity. To this end, a sub-tank (20) is attached to a bottom of a main body part (10) with a greater number of screws (25) on the front side where the stiffness is low than that on the back side where the stiffness is high.