Toner Transfer Unit Arrangement for Image Uniformity

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Solution Overview

Problem

Existing image forming apparatuses face issues with unevenness in output images due to the transfer of low-lightness colors, particularly when violet and green toner images are transferred after yellow, leading to visible defects in the final printed product.

Innovation Solution

The apparatus rearranges the toner image forming units such that the first transfer roller for the color with the highest lightness among special colors is adjacent to the first transfer roller for yellow, ensuring that low-lightness colors are not directly adjacent to the yellow transfer roller, and uses a specific order and bias voltage for transferring toner images to prevent residual toner issues.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If low-lightness colors (violet and green) are transferred after yellow using conventional transfer unit arrangement, then the image forming process can be completed, but visible unevenness and defects appear in the final printed image

Engineering Contradiction:

Improveimage forming process completionVSAvoidimage uniformity

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent applies preliminary action by transferring the yellow toner image first before transferring low-lightness colors. This sequential arrangement prevents low-lightness colors from being transferred after yellow, thereby avoiding visible unevenness and defects in the final printed image while maintaining complete image forming process

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent inverts the conventional transfer sequence by placing the yellow transfer unit at the upstream end rather than having low-lightness colors transferred after yellow. This reversed arrangement of transfer units eliminates the harmful effect of low-lightness color transfer after yellow, resolving the image uniformity issue

Inventive Principle:

Principle #13The other way round (Inversion)

2Device complexity

If transfer units are arranged in conventional sequence, then the device structure remains simple, but residual toner remains on the transfer member causing quality degradation

Engineering Contradiction:

Improvetransfer unit arrangementVSAvoidimage quality consistency

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent uses preliminary action by establishing a predetermined transfer sequence where the yellow transfer unit operates first. This sequential control prevents residual toner from low-lightness colors from remaining on the transfer member, ensuring consistent image quality without requiring complex additional cleaning mechanisms

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent maintains continuity of useful action through a optimized transfer sequence that ensures complete transfer of toner images without residual toner accumulation. The predetermined arrangement of transfer units continues the transfer process smoothly from yellow to other colors, eliminating interruptions and quality degradation

Inventive Principle:

Principle #20Continuity of useful action

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 configuration suppresses the degradation of image quality by preventing low-lightness colors from being improperly transferred, reducing the likelihood of visible unevenness in the output image and enhancing overall image quality.

Implementation Method 1

the first transfer units each transfer the image of a corresponding one of the reference colors onto the transfer member while the transfer member is being rotated

Methodology Applied

Scientific EffectElectrostatic charge transfer: Electrostatics

Data Source

PatentUS9442406B2Image forming apparatus for determining a difference in lightness between colors in toner image forming units

Publication Date: 2016.09.13 FUJIFILM BUSINESS INNOVATION CORP

AI summary

An image forming apparatus includes a transfer member, first transfer units, and second transfer units. Images of reference colors and other colors are transferred onto the transfer member being rotated. The first transfer units each transfer the image of a corresponding one of the reference colors. The second transfer units disposed upstream of the first transfer units in a rotational direction of the transfer member each transfer the image of a corresponding one of the other colors. The image of one of the reference colors is transferred by one of the first transfer units disposed most upstream. The other colors include at least one color of lightness lower than lightness of the one of the reference colors of the image transferred by the one of the transfer units. The highest-lightness image among the other colors is transferred by one of the second transfer units disposed most downstream.