Movable Secondary Transfer Unit for Image Quality

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Solution Overview

Problem

In image forming apparatuses using an intermediate transfer system, the rear portion of the medium often contacts the transfer belt after separating from the medium guide, causing disturbances to the toner image on the transfer belt, which adversely affects print quality.

Innovation Solution

The apparatus includes a secondary transfer unit with a movement mechanism that adjusts its position based on the medium's thickness, maintaining the rear portion of the medium in a spaced-apart relationship with the intermediate transfer member to prevent contact with the transfer belt during image transfer, using a controller to manage this movement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the secondary transfer unit is positioned with its rotational axis downstream of the backup member's rotational axis, then the rear portion of the medium is maintained in a spaced-apart relationship with the intermediate transfer member, preventing contact with the transfer belt and image disturbance. However, this positioning may reduce the transfer efficiency or require additional space for the movement mechanism

Engineering Contradiction:

Improveimage transfer qualityVSAvoidmovement mechanism complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The secondary transfer unit is made movable between a first position (for thick media) and a second position (for thin media) through a movement mechanism. The movement mechanism includes a drive shaft, gear, and cam that enable the secondary transfer roller to adjust its position dynamically based on medium thickness, allowing the system to adapt to different media while maintaining image quality

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the positional parameter of the secondary transfer unit based on the detected medium thickness. When medium thickness exceeds a predetermined value, the secondary transfer unit moves to the first position; otherwise, it moves to the second position. This parameter change optimizes the spaced-apart relationship between the medium rear portion and the intermediate transfer member

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the secondary transfer unit is positioned to maintain the rear portion of the medium spaced apart from the intermediate transfer member, then image disturbance is prevented. However, this may require additional space in the medium transport path or affect the compactness of the apparatus

Engineering Contradiction:

Improveprevention of image disturbanceVSAvoidapparatus space requirement

Core Design Contradiction:

ReliabilityVSVolume of moving object

Solution Approach 1:

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The apparatus is divided into functional modules including the image-forming unit, intermediate transfer member, backup member, secondary transfer unit, and movement mechanism. This segmentation allows each component to be optimized independently and facilitates compact arrangement while maintaining the necessary spaced-apart relationship

Inventive Principle:

Principle #1Segmentation

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 solution effectively prevents disturbances to the toner image, ensuring consistent print quality by maintaining the medium's rear portion away from the transfer belt, regardless of the medium's thickness, thereby enhancing the reliability of the image transfer process.

Implementation Method 1

a transfer portion at which the developed image is transferred to the medium by contact pressure

Methodology Applied

Scientific EffectFriction: Friction

Implementation Method 2

The secondary transfer roller is opposed to the backup roller through the intermediate transfer member and is configured to transfer the developed image from the intermediate transfer member to a medium

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentUS8406658B2Image forming apparatus with movable secondary transfer unit

Publication Date: 2013.03.26 OKI ELECTRIC INDUSTRY CO LTD

AI summary

An image forming apparatus includes an image-forming unit, an intermediate transfer member, a backup member and a medium transfer member. The image-forming unit is configured to form a developed image, which is transferred to the intermediate transfer member. The intermediate transfer member is entrained about the backup member. The medium transfer member is opposed to the backup member and is configured to transfer the developed image on the intermediate transfer member to a medium. The medium transfer member is also at a first position where a rotational axis of the medium transfer member lies downstream of a rotational axis of the backup member in a medium transport direction.