Light Color Toner Transfer Efficiency in Image Forming Apparatus
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Solution Overview
Problem
In image forming apparatuses using pale and dark color toners, the transfer efficiency of light color toner images is lower due to re-transfer issues, leading to irregularities in image quality and color balance, especially during secondary transfer steps where the light color toner forms the first and second layers on an intermediary transfer member.
Innovation Solution
An image forming apparatus is designed with developing devices for dark and light color toners, where the light color toner is developed prior to the dark toner, and an external additive with a specific aspect ratio and particle size is used to enhance transfer efficiency by increasing toner coverage on the intermediary transfer member, improving the stability and flowability of the toner.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If light color toner is transferred first onto the intermediary transfer member, then the light color toner forms the first layer, but the transfer efficiency is lower and image quality deteriorates due to re-transfer issues
Solution Approach 1:
The patent applies different external additives to light color toner versus dark color toner. The light color toner contains external additives with specific properties (such as silica particles with controlled surface treatment) that differ from those in dark color toner, optimizing each toner type's transfer characteristics for its specific role in the multi-layer transfer process
Solution Approach 2:
The patent modifies physical and chemical parameters of the light color toner, including particle size distribution, surface charge characteristics, and external additive composition, to enhance transfer efficiency and prevent re-transfer issues during the intermediary transfer process
2Productivity
If multilayer transfer is performed with light color toner first, then dark color toner, then color balance deviates and image irregularities occur
Solution Approach 1:
Different external additives are used for light color and dark color toners to optimize their respective transfer characteristics. This localized differentiation ensures that light color toner transfers efficiently without re-transfer issues while dark color toner maintains its color stability
Solution Approach 2:
The patent optimizes the sequence and conditions of multilayer transfer based on observed transfer efficiencies and color outcomes. By controlling the transfer parameters and toner composition, the system achieves stable color balance despite the complex multi-step transfer process
3Productivity
If spherical toner is used to improve transferability, then transfer efficiency increases, but cleaning latitude decreases
Solution Approach 1:
The patent uses composite toner particles consisting of a base resin matrix combined with specific external additives (such as inorganic particles like silica or titanium oxide). This composite structure maintains the spherical shape needed for transfer efficiency while the external additives provide surface properties that improve cleaning latitude and prevent excessive toner adhesion
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 significantly enhances the transfer efficiency of light color toner images, maintaining image quality and stability even during subsequent transfer steps, by optimizing the deposition and charge characteristics of the toner, thus preventing color shifts and irregularities.
Implementation Method 1
a photosensitive drum, on which an electrostatic latent image is formed
Implementation Method 2
a toner image is superposed on the intermediary transfer member
Implementation Method 3
a secondary transfer step for transferring four color toners transferred onto the intermediary transfer member onto a transfer material at a time
Data Source
AI summary
An image forming apparatus includes a developing apparatus for developing an electrostatic image with a developer comprising at least a toner and a first external additive, the developing apparatus including a plurality of developing devices, containing toners different in color or lightness from each other, in which at least two developing devices contain a dark color toner and a light color toner which have an identical hue and different lightnesses and the developing device containing the light color toner is subjected to a developing operation prior to another developing device; a first transfer apparatus for sequentially transferring toner images, which have been developed by the plurality of developing devices, onto an intermediary transfer member; and a second transfer apparatus for transferring the toner images from the intermediary transfer member all together onto a transfer medium The first external additive includes particles having an aspect ratio of not less than 1.0 and not more than 1.5 and a number-average particle size of not less than 0.06 μm and not more than 0.3 μm, and has a coverage thereof with respect to the light color toner larger than that with respect to the dark color toner in a transferred state on the intermediary transfer member.