Ink Storage Chamber Cross-Sectional Area Design for Detection Accuracy

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Solution Overview

Problem

Existing image forming apparatuses face issues with air entry into the recording head and inaccurate detection of ink residual amounts due to differences in liquid level lowering speeds between the ink storage chamber and the subordinate tank, leading to premature alerts or missed notifications for ink cartridge replacement.

Innovation Solution

The apparatus includes a cartridge with a first storage chamber and a cartridge attachment portion having a second storage chamber, where the cross-sectional areas are designed to control liquid level lowering speeds, ensuring precise detection of ink residual amounts and preventing air entry by maintaining liquid in the second storage chamber until necessary, with a controller notifying the user of cartridge replacement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the detecting portion detects the liquid level in the first storage chamber (cartridge), then the detection is simple, but the liquid level lowering speed in the first storage chamber is faster than in the second storage chamber, causing inaccurate residual amount detection

Engineering Contradiction:
Improvedetection structureVSAvoidresidual amount detection accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent introduces a second storage chamber (subordinate tank) as an intermediary component between the first storage chamber (cartridge) and the liquid ejection head. This subordinate tank acts as a buffer that equalizes the liquid level lowering speeds, allowing the detecting portion to accurately measure residual ink by detecting the liquid level in the second storage chamber where the lowering speed is synchronized with the actual consumption rate at the ejection head.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If the second storage chamber is designed with larger cross-sectional area to slow down liquid level lowering, then the liquid level lowering speed in the second storage chamber matches the consumption rate, but the apparatus size increases

Engineering Contradiction:
Improveliquid level detection accuracyVSAvoidapparatus size
Core Design Contradiction:
Measurement precisionVSArea of stationary object

Solution Approach 1:

The patent positions the second storage chamber (subordinate tank) vertically above the first storage chamber (cartridge) in the up-down direction, utilizing the vertical dimension to accommodate the additional chamber without significantly increasing the horizontal footprint. This vertical stacking arrangement allows the system to maintain accurate liquid level detection while minimizing the overall apparatus size.

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

3Measurement precision

If the detecting portion detects liquid level in the second storage chamber, then accurate residual amount detection is achieved, but the liquid may run out in the first storage chamber before detection, causing air entry into the recording head

Engineering Contradiction:
Improveresidual amount detection accuracyVSAvoidair entry prevention
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent designs the second storage chamber (subordinate tank) with a larger cross-sectional area than the first storage chamber, creating a buffer capacity that ensures liquid remains in the second storage chamber longer than in the first storage chamber. This preliminary design ensures that when the detecting portion detects the liquid level in the second storage chamber, there is still liquid remaining in the first storage chamber to prevent air from entering the recording head through the connecting portion.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3437881B1Image forming apparatus and image forming system
Publication Date: 2020.07.08 BROTHER KOGYO KK
  • EP3437881B1 patent drawingFigure 1A~1B
  • EP3437881B1 patent drawingFigure 2
  • EP3437881B1 patent drawingFigure 3

AI summary

In an image forming apparatus, a cartridge includes: a first storage chamber; and a supply portion. A cartridge attachment portion includes: a connecting portion; and a second storage chamber. The connecting portion is disposed at a first height and connectable to the supply portion. A detecting portion is configured to detect one of a level of a liquid stored in the first storage chamber and at a position adjacent to the supply portion and a level of the liquid stored in the second storage chamber and at a position adjacent to the connecting portion. The first storage chamber has a first cross-sectional area taken along a horizontal plane at a predetermined height between the first height and a second height above the first height. The second storage chamber has a second cross-sectional area taken along the horizontal plane. The second cross-sectional area is greater than the first cross-sectional area.