Duplex Fixing Temperature Control for Image Formers

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Solution Overview

Problem

In image forming apparatuses, duplex printing often results in electric discharge noise (white dots) due to increased sheet resistance from heat fixation, and insufficient heat application for the second side, leading to fixing defects.

Innovation Solution

The apparatus adjusts heat settings for duplex printing by applying a lower heat amount for the first side and a higher heat amount for the second side, using a controller to set optimal fixing temperatures based on sheet resistance, to prevent electric discharge noise and ensure sufficient heat for fixation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the fixing temperature for the first-side printing is controlled to have an optimum value to prevent curling, then the recording sheet curling is prevented, but the fixing temperature for the second-side printing becomes insufficient causing fixing defects

Engineering Contradiction:

Improveprevention of recording sheet curlingVSAvoidfixing quality of second-side printing

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The fixing temperature is changed from a static constant value to a dynamic variable that adapts based on printing mode (simplex or duplex) and side (first-side or second-side). The controller adjusts the fixing temperature to different optimal values depending on the specific printing conditions, allowing the system to maintain both curl prevention and proper fixing quality under varying operational modes.

Inventive Principle:

Principle #15Dynamics

2Ease of operation

If the fixing temperature for the second-side printing is kept constant, then the device operation is simple, but electric discharge noise occurs due to insufficient heat application

Engineering Contradiction:

Improvesimplicity of device operationVSAvoidelectric discharge noise

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The fixing temperature parameter is modified based on the printing conditions. For duplex printing on the second-side, the controller increases the fixing temperature compared to simplex printing or first-side printing. This parameter adjustment ensures sufficient heat application to prevent electric discharge noise while maintaining operational simplicity through automated control.

Inventive Principle:

Principle #35Parameter changes

3Manufacturing precision

If the fixing temperature is increased for the first-side printing, then the fixing quality is improved, but the sheet resistance increases causing electric discharge noise in the second-side printing

Engineering Contradiction:

Improvefixing quality of first-side printingVSAvoidelectric discharge noise in second-side printing

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

Different fixing temperatures are applied to different sides of the recording sheet based on their specific requirements. The first-side receives a lower fixing temperature to prevent excessive moisture reduction and maintain low sheet resistance, while the second-side receives a higher fixing temperature to ensure proper fixing quality. This localized quality approach resolves the contradiction between fixing quality and electric discharge prevention.

Inventive Principle:

Principle #3Local quality

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 minimizes electric discharge noise and ensures proper heat application for both sides of the paper, enhancing print quality and preventing fixing defects in duplex printing.

Implementation Method 1

the recording sheet is heated and pressurized at a fixing unit to fix the toner image on the recording sheet

Methodology Applied

Scientific EffectThermal energy transfer: Conduction (thermal)

Implementation Method 2

the toner, which has been transferred to the recording sheet at the transfer unit, is melted and fixed on the recording sheet

Methodology Applied

Scientific EffectMelting: Melting

Implementation Method 3

the recording sheet is heated and pressurized at a fixing unit to fix the toner image on the recording sheet

Methodology Applied

Scientific EffectCompression: Compression

Implementation Method 4

a transfer voltage is applied to a transfer roller to transfer electrified toner from the image carrier to the recording sheet

Methodology Applied

Scientific EffectElectrostatic transfer: Electrostatics

Data Source

PatentUS9599939B2Image forming apparatus with different fixing temperatures for each side in duplex fixing

Publication Date: 2017.03.21 KONICA MINOLTA INC

AI summary

An image forming apparatus includes an image carrier to carry a toner image. A transfer unit transfers the toner image to a sheet. A fixing unit fixes the toner image on the sheet. The sheet with the image is discharged to a sheet discharge tray. A circular conveyance path turns over the sheet past the transfer unit and the fixing unit and passes the sheet through the transfer unit and the fixing unit again. A heat amount setting section sets an amount of heat applied by the fixing unit when fixing of the sheet is executed. In duplex printing, a first heat amount for fixing the toner image on a first side of the sheet is smaller than a reference heat amount for simplex printing whereas a second heat amount for fixing the toner image on a second side of the sheet is larger than the reference heat amount.