Conveying Roller Temperature Control for Gloss Uniformity
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Solution Overview
Problem
In image forming apparatuses, the uneven cooling of toner on sheets due to low-temperature rubber rollers causes gloss differences and unevenness on the surface, particularly noticeable in thick, coated, or waterproof sheets.
Innovation Solution
The apparatus includes a control unit that controls the sheet to pass through conveying rollers multiple times before printing, ensuring the rubber rollers' surface temperature matches the sheet's temperature, preventing heat transfer and maintaining even toner cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If low-temperature rubber rollers are used to convey the sheet, then the cost is reduced and the rollers are easier to manufacture, but the toner on the sheet cools unevenly causing gloss differences and surface unevenness
Solution Approach 1:
The patent applies preliminary action by pre-heating the rubber rollers before they contact the hot toner on the sheet. The rollers are heated to a temperature close to the toner temperature (e.g., 60-80°C) so that when the sheet passes through, minimal heat transfer occurs. This preliminary heating prevents the rollers from extracting heat from the toner, thereby maintaining uniform gloss and preventing surface unevenness while still using cost-effective rubber materials.
2Ease of manufacture
If the conveying rollers are made of rubber material, then the cost is reduced, but the rollers remove heat from the toner causing temperature differences and gloss unevenness
Solution Approach 1:
The patent implements preliminary action by heating the rubber rollers to a temperature close to the toner temperature before the sheet passes through. This pre-heating ensures that when contact occurs, the temperature difference between the roller and toner is minimal, preventing heat extraction from the toner. This allows the use of inexpensive rubber rollers while maintaining uniform toner temperature and preventing gloss unevenness.
Solution Approach 2:
The patent applies parameter changes by adjusting the temperature parameter of the rubber rollers. Instead of using cold rubber rollers that naturally cool the toner, the rollers are heated to a specific temperature range (60-80°C) to match the toner temperature. This parameter change transforms the thermal interaction from heat extraction to thermal equilibrium, maintaining toner temperature uniformity while keeping the rollers inexpensive.
3Manufacturing precision
If the sheet passes through the conveying rollers multiple times, then the roller temperature matches the sheet temperature preventing heat transfer, but the processing time increases
Solution Approach 1:
The patent applies preliminary action by pre-heating the rubber rollers before the sheet passes through. This preliminary heating to near-toner-temperature ensures that when the sheet contacts the rollers, minimal heat transfer occurs, maintaining uniform gloss immediately on the first pass. This eliminates the need for multiple passes through the rollers, thereby reducing processing time while maintaining gloss uniformity.
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 ensures even gloss across the sheet surface, reducing stripe-like unevenness and providing satisfactory printing results, especially for glossy or thick sheets.
Implementation Method 1
The low temperature rubber rollers, through contact with the sheet, remove heat from the toner on the sheet while conveying the high temperature sheet
Data Source
AI summary
According to one embodiment, an image forming apparatus includes a printing unit, a fixing device, a conveying roller, and a control unit. The printing unit is configured to form an image by transferring toner onto a sheet. The fixing device is configured to heat and fix the toner onto the sheet. The fixing device is disposed on the downstream side of the printing unit. The conveying roller is configured to convey the sheet from the fixing device. The conveying roller is disposed on the downstream side of the fixing device. The control unit is configured to control the sheet heated by the fixing device to pass through the conveying roller a plurality of times before the image is formed on the sheet by the printing unit.