Image Magnification Control via Secondary Transfer Speed

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Solution Overview

Problem

Existing image forming apparatuses face productivity issues due to time-consuming adjustments in rotation speeds of polygon mirrors and photoconductive drums to match longitudinal and lateral magnifications, leading to misalignment and color shifts during the intermediate and secondary transfer processes, especially in color image forming systems.

Innovation Solution

An image forming apparatus that controls longitudinal magnification by varying the rotation speed of the secondary transfer member while keeping the intermediate transfer member's speed constant, using a conversion table to adjust the rotation speed based on the target magnification, and applying lubricants to prevent misalignment and slipping during the transfer process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the rotation speed of the intermediate transfer member and secondary transfer member are changed to adjust longitudinal magnification, then the image magnification can be controlled, but misalignment of transfer and color shift occur due to speed differences between transfer members

Engineering Contradiction:

Improveimage magnification controlVSAvoidtransfer alignment

Core Design Contradiction:

Measurement precisionVSManufacturing precision

Solution Approach 1:

The patent separates the magnification control function from the intermediate transfer member and assigns it exclusively to the secondary transfer member. This segmentation allows the intermediate transfer member to maintain constant speed (ensuring transfer alignment) while the secondary transfer member adjusts its speed independently to control longitudinal magnification, thereby resolving the contradiction between magnification control and transfer alignment.

Inventive Principle:

Principle #1Segmentation

2Measurement precision

If the rotation speed of polygon mirror and photoconductive drum are changed to adjust magnification, then the longitudinal magnification can be controlled, but the adjustment time increases and productivity decreases

Engineering Contradiction:

Improvelongitudinal magnificationVSAvoidadjustment time

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The patent extracts the magnification control function from the exposure system (polygon mirror and photoconductive drum) and relocates it to the secondary transfer member's speed control. This extraction eliminates the need for time-consuming adjustments in the exposure system, as magnification can be adjusted simply by changing the secondary transfer member's rotation speed, thereby improving productivity while maintaining precise magnification control.

Inventive Principle:

Principle #2Taking out (Extraction)

3Measurement precision

If the drive speed of the secondary transfer member is changed to control magnification, then the longitudinal magnification can be adjusted, but misalignment and color shift occur due to interference with the intermediate transfer member

Engineering Contradiction:

Improvelongitudinal magnification adjustmentVSAvoidtransfer position alignment

Core Design Contradiction:

Measurement precisionVSManufacturing precision

Solution Approach 1:

The patent segments the transfer process into two independent speed control systems: the intermediate transfer member operates at constant speed to ensure stable transfer positioning, while the secondary transfer member independently adjusts its speed to control longitudinal magnification. This segmentation eliminates the interference and speed mismatch problems that occur when both members are adjusted simultaneously, resolving the contradiction between magnification adjustment and transfer alignment.

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 approach allows for precise control of image magnification without requiring time-consuming adjustments, reducing the risk of misalignment and color shifts, thereby enhancing productivity and maintaining image quality across various sheet types.

Implementation Method 1

the control section controls a magnification of the toner image transferred onto the sheet at a secondary transfer position in a sheet conveyance direction to be a target value by changing a rotation speed of the second transfer section

Methodology Applied

Scientific EffectSpeed control:

Implementation Method 2

applying lubricants to prevent misalignment and slipping during the transfer process

Methodology Applied

Scientific EffectLubrication: Lubrication

Data Source

PatentUS8971742B2Image forming apparatus to change image magnification by controlling sheet conveyance speed

Publication Date: 2015.03.03 KONICA MINOLTA BUSINESS TECH INC

AI summary

Provided is an image forming apparatus which enables control to change a longitudinal magnification of an image transferred on a sheet in a sheet conveyance direction by changing a rotation speed of a second transfer section while prohibiting misalignment of transfer without requiring a changing time of the longitudinal magnification which causes the decreasing of productivity.