Fixing Roller Temperature Control for Overheating Prevention
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Solution Overview
Problem
Conventional image forming apparatuses face issues with overheating of the fixing member, leading to breakdown and image deterioration due to temperature discrepancies between the sheet passing and non-passing areas, especially during continuous printing with varying paper sizes.
Innovation Solution
An image forming apparatus with a temperature detection system and control unit that adjusts productivity in multiple steps based on the size of the recording medium and surface temperature of the non-passing area, reducing overheating by changing the control temperature and productivity accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the diameter or thickness of the fixing roller is reduced to reduce heat capacity, then power consumption is reduced and productivity is improved, but the sheet non-passing area becomes prone to overheating causing breakdown of the fixing member
Solution Approach 1:
The heating system is segmented into multiple independent heaters (main heater and sub-heaters) positioned at different locations along the fixing roller. Each heater can be controlled independently based on temperature feedback from corresponding detection elements, allowing localized heat management to prevent overheating in non-passing areas while maintaining productivity with a thinner roller design
Solution Approach 2:
Temperature detection elements are positioned to detect temperatures at both sheet passing and sheet non-passing areas of the fixing roller. The control system uses this feedback to dynamically adjust the power supplied to different heaters, preventing overheating in non-passing areas while maintaining the thin roller design for high productivity
2Stability of the object's composition
If multiple heaters are used to maintain temperature during continuous printing, then temperature maintaining property is improved, but the sheet non-passing area becomes overheated causing breakdown
Solution Approach 1:
Different regions of the fixing roller are equipped with different heating capabilities - the main heater serves the central sheet passing area while sub-heaters serve the end non-passing areas. Temperature detection elements are also positioned at different locations to monitor local temperatures, enabling localized quality control where each region receives appropriate heat management tailored to its specific thermal characteristics and usage pattern
Solution Approach 2:
The control system dynamically changes the power supply parameters to different heaters based on real-time temperature feedback. When the sheet non-passing area temperature approaches the heat resistance limit, the control system reduces power to the sub-heaters or stops heating in those regions, preventing overheating while maintaining temperature stability in the sheet passing area during continuous printing
3Productivity
If the thermostat temperature is set high to maintain productivity, then printing speed is maintained, but toner excessively melts and adheres to the fixing member causing hot offset
Solution Approach 1:
Temperature detection elements are positioned to detect temperatures in the sheet non-passing area before sheets are fed. The control system uses this advance temperature information to preemptively adjust heater power, preventing the sheet passing area temperature from rising to levels that would cause toner to excessively melt and adhere to the fixing roller, thus preventing hot offset while maintaining productivity
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 solution effectively suppresses overheating of the fixing member, maintaining productivity and extending the lifespan of the fixing roller and pressure roller by adjusting heat supply based on detected temperatures and paper sizes.
Implementation Method 1
a fixing member constituted of a heated rotary member heated by a heating device
Implementation Method 2
The temperature detection device detects surface temperature of the heated rotary member in a non-passing area the recording medium does not pass
Implementation Method 3
The fixing device melts the toner while conveying the paper sheet, using a fixing member constituted of a heated roller
Data Source
AI summary
An image forming apparatus includes an image forming unit, a fixing device, a temperature detection device, a driving device, a printed sheet number counting unit, a fixing voltage power supply, and a control unit. The fixing device includes a fixing member constituted of a heated rotary member heated by a heating device and a pressure member contacting the heated rotary member to form a fixing nip. The temperature detection device detects surface temperature of the heated rotary member in a non-passing area. The control unit changes a productivity in two or more steps from a default setting, on the basis of an accumulated number of printed sheets from start of a productivity change mode counted by the printed sheet number counting unit, and the surface temperature of the non-passing area detected by the temperature detection device, and changes control temperature of the fixing member in accordance with the productivity.