Developer Particle Size Control for Tint Stability

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Solution Overview

Problem

The challenge in electrophotographic image formation is the change in tint of toner images due to the proportion of toner particles containing no brilliant pigment, which affects the consistency of yellow, magenta, and cyan tones, especially when using brilliant toners like gold or silver.

Innovation Solution

A developer comprising particles with a binder resin, aluminum brilliant pigment, yellow pigment, magenta pigment, reddish-orange fluorescent dye, and yellow fluorescent dye, where the volume average particle diameter of brilliant pigments is controlled to ensure less than 4% of particles have diameters in the range from 4 µm to 1.2 times the average diameter, reducing the proportion of particles without brilliant pigment and thus minimizing tint changes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If brilliant pigments with diameter of 5-10 μm are used in toner particles, then the brilliance effect is achieved, but the toner particles containing no brilliant pigment increase, causing yellow tint to decrease and tint consistency to deteriorate

Engineering Contradiction:
Improvebrilliance effectVSAvoidtint consistency
Core Design Contradiction:
Illumination intensityVSStability of the object's composition

Solution Approach 1:

The invention changes the particle size parameter of brilliant pigments to a specific range (0.3-2.0 μm) and controls the particle size distribution of toner particles, ensuring that at least 80% of toner particles have diameters within 3.0-6.0 μm. This parameter optimization allows brilliant pigments to be effectively contained within toner particles while maintaining consistent tint across continuous printing operations.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention creates local quality differentiation by specifying that at least 80% of toner particles must contain brilliant pigment, while allowing other particles to have different compositions. This localized control ensures sufficient brilliance effect while maintaining overall tint consistency through the majority of particles containing the brilliant pigment.

Inventive Principle:
Principle #3Local quality

2Quantity of substance

If toner particles with larger size are used to contain brilliant pigment, then the brilliant pigment can be contained, but the proportion of particles without brilliant pigment increases, affecting image quality

Engineering Contradiction:
Improvebrilliant pigment contentVSAvoidparticle size control
Core Design Contradiction:
Quantity of substanceVSManufacturing precision

Solution Approach 1:

The invention optimizes particle size parameters by controlling brilliant pigment diameter to 0.3-2.0 μm and toner particle diameter to 3.0-6.0 μm (with at least 80% within this range). This precise parameter control ensures brilliant pigment is effectively contained while maintaining consistent particle size distribution and preventing excessive variation in particle dimensions.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention applies preliminary action by pre-controlling the particle size distribution of toner particles before image formation, ensuring that at least 80% of particles fall within the 3.0-6.0 μm range and contain brilliant pigment. This preliminary control prevents tint variation during continuous printing operations.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3276421B1Developer, developer storage body, developing device and image forming apparatus
Publication Date: 2020.04.22 OKI DATA CORP
  • EP3276421B1 patent drawingFigure 1
  • EP3276421B1 patent drawingFigure 2
  • EP3276421B1 patent drawingFigure 3

AI summary

A developer including developer particles. Each developer particle includes a binder resin, a brilliant pigment whose principal component is aluminum, a yellow pigment, a magenta pigment, a reddish-orange fluorescent dye, and a yellow fluorescent dye. When an average particle diameter of the brilliant pigments included in the developer particles is expressed as D (µm), a number proportion of the developer particles having particle diameters in a range from 4 µm to 1.2×D µm in the whole developer particles is less than or equal to 4%.