Dual-Sensor Ink Level Detection for Continuous Printing

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Solution Overview

Problem

Existing image forming apparatuses with liquid discharge recording types face challenges in maintaining optimal ink supply to the sub-tank during printing, leading to interruptions and reduced printing speed due to imprecise detection of ink levels and negative pressure fluctuations.

Innovation Solution

The apparatus employs a dual-sensor system where the first sensor on the carriage detects the displacement member's position during printing, and the second sensor on the body of the apparatus confirms the fully filling state, allowing continuous ink supply without interrupting the printing process by calculating the differential supply amount based on the displacement change.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single sensor on the carriage detects ink level, then the structure is simple, but printing must be interrupted to confirm full filling state

Engineering Contradiction:
Improvesensor system structureVSAvoidprinting speed
Core Design Contradiction:
Device complexityVSProductivity

Solution Approach 1:

The ink level detection function is segmented into two parts: a first sensor on the carriage for real-time monitoring during printing, and a second sensor on the body for confirming full filling state. This segmentation allows continuous printing while maintaining accurate ink level detection without requiring complete carriage stops.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The first sensor detects the displacement member position preliminarily during printing to determine when ink supply is needed, allowing the system to prepare for ink supply without interrupting the printing process, thus maintaining productivity.

Inventive Principle:
Principle #10Preliminary action

2Measurement precision

If ink supply is performed only when carriage is at detection position, then detection is accurate, but printing speed decreases due to interruptions

Engineering Contradiction:
Improveink level detection precisionVSAvoidprinting speed
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The first sensor enables continuous ink level monitoring during printing operations, allowing the system to maintain accurate detection without stopping the carriage. This ensures both measurement precision and continuous printing productivity.

Inventive Principle:
Principle #20Continuity of useful action

3Device complexity

If negative pressure is not maintained properly, then ink supply is simple, but ink seeping or dripping occurs from nozzles

Engineering Contradiction:
Improvenegative pressure control mechanismVSAvoidink discharge control
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The dual-sensor system provides feedback on the displacement member position, which reflects the ink level and negative pressure state in the sub-tank. This feedback enables the control system to adjust ink supply to maintain optimal negative pressure, preventing ink seeping or dripping while ensuring reliable ink discharge.

Inventive Principle:
Principle #23Feedback

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 approach enables continuous ink supply to the sub-tank during printing, maintaining optimal negative pressure and improving printing speed and efficiency by avoiding interruptions and errors in ink detection.

Implementation Method 1

a negative pressure creating part that includes a resilient member that gives such force to the flexible member to cause it to move outward

Methodology Applied
Scientific EffectElastic force: Elasticity

Implementation Method 2

The sub-tank is provided with a displacement member (also referred to as a detection member or a detection filler) which changes a position itself as a position of the flexible member changes

Methodology Applied
Scientific EffectMechanical displacement: Displacement

Implementation Method 3

a first photo sensor fixed to the carriage for detecting the position of the displacement member

Methodology Applied
Scientific EffectPhotoelectric detection: Photoelectric Effect

Data Source

PatentEP2605912B1Image forming apparatus
Publication Date: 2016.06.29 RICOH CO LTD
  • EP2605912B1 patent drawingFigure 1
  • EP2605912B1 patent drawingFigure 2
  • EP2605912B1 patent drawingFigure 3

AI summary

In an image forming apparatus, a first detection part and a second detection part, each for detecting a position of a displacement member that changes its position according to a remaining amount of liquid in a sub-tank, are provided to a carriage carrying the sub-tank and a recording head, and a body of the image forming apparatus, respectively. A first position is a position of the displacement member detected by the first detection part such that the remaining amount of liquid in the sub-tank is smaller than that at a second position detected by the second detection part. The liquid is supplied to the sub-tank of a differential supply amount, corresponding to a displacement amount of the displacement member between a position detected by the first detection part and a position detected by the second detection part, after the first detection part detects the displacement member.