Sheet Cooling Mechanism for Image Forming Apparatus
Solution Overview
Problem
High-speed image forming processes often result in uneven glossiness of toner images due to insufficient cooling of sheets before they reach post-processing devices, leading to issues with conveying rollers, which existing solutions attempt to address with larger and more costly cooling systems.
Innovation Solution
A sheet conveying mechanism using single-diameter rollers made of thermally conductive materials like EPC rubber and POM resin, combined with a cooling path and guide surfaces, to cool and convey sheets uniformly, preventing uneven glossiness without the need for additional cooling fans or belts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If sheets are conveyed at high speed through the fixing device, then productivity is improved, but the sheets remain hot and cause uneven glossiness in post-processing
Solution Approach 1:
The patent introduces an intermediate sheet conveying device as a mediator between the fixing device and post-processing device. This intermediary component provides a controlled cooling environment where sheets pass through a cooling section with cooled rollers and guides, allowing temperature reduction without stopping the high-speed printing process.
Solution Approach 2:
The conveying path is segmented into distinct functional sections: a fixing section for high-speed image fixation, a cooling section with cooled rollers and guides for temperature reduction, and a post-processing section. This segmentation allows each section to optimize its function independently while maintaining overall high-speed operation.
2Temperature
If cooling fans and belts are added to cool sheets, then sheet cooling is improved, but apparatus size and cost increase
Solution Approach 1:
The cooling function is merged with the sheet conveying function. The cooled rollers and cooling guides serve dual purposes: they convey the sheets through the intermediate device while simultaneously cooling them. This eliminates the need for separate cooling fans and belts, reducing apparatus complexity and cost.
Solution Approach 2:
The cooling system uses the sheet conveying mechanism itself to provide cooling. The rollers and guides are cooled and directly contact the sheets during normal conveying operation, allowing the system to cool sheets using its own existing structural components rather than requiring additional dedicated cooling equipment.
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
Effectively cools sheets to prevent uneven glossiness, maintaining surface temperature below the toner's glass transition temperature, ensuring consistent image quality and reducing apparatus size and cost.
Implementation Method 1
a sheet conveying mechanism which conveys a sheet on which an image has been fixed at a heat-fixing process, while cooling it
Data Source
Figure 1
Figure 2(a)~2(b)
AI summary
A sheet conveying mechanism (B), which conveys a sheet on which a toner image has been fixed at a heat-fixing unit (7), includes conveying rollers (10a,10b,11a,11b) each of which is a single roller having the same diameter throughout a width for passing the sheet and is disposed in a predetermined section for a cooling process after the heat-fixing process, and includes a sheet conveying guide (20a) provided on the predetermined section and having a sheet-passing surface made in the same shape throughout the width for passing the sheet.