Image Forming Apparatus Uniform Density Fixing Temperature Control

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Solution Overview

Problem

In image forming apparatuses, uneven brightness occurs in finished images due to variations in toner melting during the fixing process, especially in regions with uniform density, leading to suboptimal image quality.

Innovation Solution

An image forming apparatus that calculates the size parameter of uniform density regions in toner images and adjusts the fixing temperature of the fixing section to prevent uneven brightness, ensuring high-quality image output by maintaining or increasing the temperature based on calculated thresholds for area, area ratio, or data amount of these regions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a given fixing temperature is used in the fixing process, then the fixing operation can be performed efficiently, but uneven brightness occurs due to variation in toner melting in uniform density regions

Engineering Contradiction:
Improvefixing operation efficiencyVSAvoidimage quality uniformity
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The fixing temperature is changed from a static given value to a dynamic value that varies based on the coverage rate calculated from image data. The control section adjusts the fixing temperature according to the size parameter of uniform density regions, making the fixing process adaptive to different image characteristics and preventing uneven brightness while maintaining efficiency.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The invention changes the physical parameter of fixing temperature based on the coverage rate and size parameter of uniform density regions. By calculating the coverage rate from image data and determining the size parameter of uniform density regions, the system adjusts the fixing temperature to ensure uniform toner melting across different region types, thereby eliminating uneven brightness while preserving fixing efficiency.

Inventive Principle:
Principle #35Parameter changes

2Manufacturing precision

If the fixing temperature is increased to prevent uneven brightness, then image quality improves, but energy consumption increases

Engineering Contradiction:
Improveimage quality uniformityVSAvoidfixing section energy consumption
Core Design Contradiction:
Manufacturing precisionVSUse of energy by moving object

Solution Approach 1:

Instead of uniformly increasing the fixing temperature across the entire image, the invention applies localized temperature adjustment based on the coverage rate and size parameter of uniform density regions. The control section calculates which specific regions require higher temperatures and adjusts the fixing temperature accordingly, ensuring uniform toner melting only where needed rather than across the whole image, thus improving image quality while minimizing energy consumption.

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

The solution effectively suppresses the occurrence of uneven brightness by precisely controlling the fixing temperature, resulting in high-quality images by ensuring uniform toner melting across all regions of the image.

Implementation Method 1

The fixing section fixes the toner image on the printing paper through thermo compression

Methodology Applied
Scientific EffectThermal melting: Melting

Implementation Method 2

The fixing section fixes the toner image on the printing paper through thermo compression

Methodology Applied
Scientific EffectThermal compression: Compression

Data Source

PatentEP2657791B1Image forming apparatus
Publication Date: 2019.07.10 KYOCERA DOCUMENT SOLUTIONS INC
  • EP2657791B1 patent drawingFigure 1
  • EP2657791B1 patent drawingFigure 2
  • EP2657791B1 patent drawingFigure 3

AI summary

An image forming apparatus includes a toner image forming section, a fixing section, and a control section. The toner image forming section forms a toner image based on image data for printing on printing paper. The fixing section fixes the toner image on the printing paper through thermocompression. The control section controls a toner image forming operation by the toner image forming section and a fixing operation by the fixing section. The control section calculates a size parameter associated with a size of a uniform density region included in the toner image based on the image data for the printing and controls a fixing temperature of the fixing section according to a calculation result.