Heated Conveying Rollers for Gloss Uniformity
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Solution Overview
Problem
The existing image forming apparatuses experience gloss unevenness on sheets due to temperature differences in toner cooling, particularly when using glossy coated or waterproof papers, as the conveying rollers have lower temperatures than the toner, causing uneven heat transfer and cooling.
Innovation Solution
A sheet conveying apparatus with a conveying roller system that includes heating units to adjust the temperature of the rollers to match the toner temperature, ensuring consistent cooling and reducing gloss unevenness by using temperature sensors and heaters to control the temperature of the rollers in contact with the toner.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the conveying roller uses rubber rollers with lower temperature to convey the sheet, then the sheet can be conveyed smoothly, but the toner on the sheet experiences uneven cooling and gloss unevenness occurs
Solution Approach 1:
The patent changes the temperature parameter of the conveying roller from a low temperature state to a high temperature state (matching or exceeding toner temperature) to prevent unwanted heat transfer. This parameter change eliminates the thermal gradient between the roller and toner, thereby preventing uneven cooling and gloss variations while maintaining smooth sheet conveyance
Solution Approach 2:
The patent creates a thermal equipotential condition by heating the conveying roller to the same temperature as the toner. When both are at equal temperature, no heat transfer occurs between them, eliminating the uneven cooling effect that causes gloss unevenness while preserving the smooth conveyance function
2Speed
If the conveying roller temperature is kept low for efficient heat dissipation, then cooling speed increases, but temperature difference across the toner surface causes gloss unevenness
Solution Approach 1:
The patent fundamentally changes the temperature parameter of the conveying roller from low to high (matching toner temperature). This eliminates the thermal gradient that causes uneven cooling patterns across the toner surface, preventing gloss unevenness while still allowing controlled cooling to occur as the toner naturally dissipates heat to the environment
3Manufacturing precision
If heating units are added to the conveying roller to match toner temperature, then gloss unevenness is suppressed, but device complexity increases
Solution Approach 1:
The patent merges the heating function with the conveying roller by integrating heating units directly into the roller structure. This combination allows the conveying roller to simultaneously perform its original conveyance function and the new heating function, maintaining gloss uniformity without requiring a completely separate heating system
Solution Approach 2:
The conveying roller is transformed into a multi-functional component that both conveys sheets and controls toner temperature. By incorporating heating capability, the roller serves dual purposes: mechanical conveyance and thermal management, thereby suppressing gloss unevenness while minimizing additional device complexity
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 maintains consistent toner temperature across the sheet, preventing heat deprivation and thus suppressing gloss unevenness on the printing surface, especially on glossy coated or waterproof papers.
Implementation Method 1
a heating unit configured to heat the plural rollers of the conveying roller
Implementation Method 2
a temperature control unit configured to control the heating unit such that the temperature of the plural rollers approaches toner temperature of the sheet passing through the conveying roller
Data Source
AI summary
According to one embodiment, a sheet conveying apparatus includes: a fixing device configured to heat, with a heat roller, a sheet having a toner image transferred thereon and fix a toner on the sheet; a conveying roller arranged downstream of the fixing device and including plural rollers configured to convey the sheet from the fixing device; a heating unit configured to heat the plural rollers of the conveying roller; and a temperature control unit configured to control the heating unit such that the temperature of the plural rollers approaches the toner temperature of the sheet passing through the conveying roller.