Inkjet Recording Head Preliminary Discharge Control

Solution Overview

Problem

Ink jet recording apparatuses face issues with declining ink discharge performance and increased waste ink due to moisture evaporation in nozzles, especially with multi-color inks and smaller nozzles, leading to frequent preliminary discharge and suction operations, which can result in unnecessary ink discharge.

Innovation Solution

An inkjet recording apparatus with a preliminary discharge unit that adjusts the discharge operation based on the capping time of the recording head, varying the number of ink droplets discharged for different colors to maintain humidity and prevent density unevenness, thereby reducing waste ink and maintaining high image quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a cap is provided to cover the recording head, then moisture evaporation is prevented and discharge performance is maintained, but the cap itself transmits moisture and ink still dries over long periods requiring preliminary discharge

Engineering Contradiction:

Improvedischarge performanceVSAvoidwaste ink

Core Design Contradiction:

ReliabilityVSLoss of substance

Solution Approach 1:

The patent performs preliminary discharge of ink with high water mole fraction in the cap before capping to maintain humidity inside the cap. This preliminary action ensures that when the cap is later opened, the ink in the nozzles has not dried out, preventing discharge defects and eliminating the need for subsequent preliminary discharge operations that would waste ink.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent changes the parameter of ink composition by selectively discharging ink with higher water mole fraction in the cap before capping. This parameter change maintains the humidity environment inside the cap, preventing ink from drying out during storage and reducing the frequency of waste-generating preliminary discharge operations.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If preliminary discharge is performed in the cap before capping, then humidity is maintained for a certain period, but unnecessary ink is discharged if recording starts shortly after capping increasing waste

Engineering Contradiction:

Improvehumidity maintenanceVSAvoidwaste ink

Core Design Contradiction:

ReliabilityVSLoss of substance

Solution Approach 1:

The patent performs preliminary discharge of ink with high water mole fraction in the cap before capping to maintain humidity inside the cap. This preliminary action ensures that when the cap is later opened, the ink in the nozzles has not dried out, preventing discharge defects and eliminating the need for subsequent preliminary discharge operations that would waste ink.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent monitors the timing of recording operations after capping and adjusts whether to perform preliminary discharge based on this feedback. If recording starts shortly after capping, the system determines that preliminary discharge is unnecessary and skips it, thereby avoiding waste ink while still maintaining reliability when needed.

Inventive Principle:

Principle #23Feedback

3Manufacturing precision

If multi-color inks with different moisture fractions are used, then color gamut and gradation are improved, but each color dries at different rates requiring frequent preliminary discharge

Engineering Contradiction:

Improveimage qualityVSAvoidrecording efficiency

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The patent performs preliminary discharge of ink with high water mole fraction in the cap before capping to maintain humidity inside the cap. This preliminary action ensures that when the cap is later opened, the ink in the nozzles has not dried out, preventing discharge defects and eliminating the need for subsequent preliminary discharge operations that would waste ink.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent changes the parameter of ink composition by selectively discharging ink with higher water mole fraction in the cap before capping. This parameter change maintains the humidity environment inside the cap, preventing ink from drying out during storage and reducing the frequency of waste-generating preliminary discharge operations.

Inventive Principle:

Principle #35Parameter changes

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

The solution effectively reduces the frequency of preliminary discharge operations and waste ink while ensuring high image quality by tailoring the discharge operation to the capping time and color-specific moisture levels, addressing the challenges of moisture evaporation and ink density changes.

Implementation Method 1

moisture in the ink in the nozzle evaporates and the viscosity of the ink rises

Methodology Applied

Scientific EffectEvaporation: Evaporation

Implementation Method 2

discharge an ink droplet from a recording head

Methodology Applied

Scientific EffectThermal energy conversion:

Data Source

PatentUS8794728B2Ink jet recording apparatus

Publication Date: 2014.08.05 CANON KK

AI summary

An inkjet recording apparatus includes a recording head, a cap, and a preliminary discharge unit. The recording head can discharge a plurality of types of ink. The cap caps a discharge port face of the recording head. The preliminary discharge unit causes the recording head to execute a preliminary discharge. The preliminary discharge unit changes a preliminary discharge operation according to a length of time during which the discharge port face is capped by the cap.