Fixing Roller Duty-Ratio Control for Temperature Uniformity
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Solution Overview
Problem
Existing image forming apparatuses face challenges in maintaining optimal temperature gradients across the fixing roller to ensure uniform toner fixation on paper sheets, especially under varying environmental conditions and paper sizes, leading to potential image quality issues.
Innovation Solution
The apparatus incorporates a heat roller with a first and second heater, where the first heater heats the center portion and the second heater heats the end portions, with a control unit adjusting the duty ratios of the heaters based on detected temperature differences and environmental conditions to maintain target temperatures and gradients, using a correction value derived from stored data to optimize power supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the first heater heats the center portion and the second heater heats the end portions with fixed duty ratios, then the temperature distribution is simplified to control, but the temperature uniformity across different paper sizes and environmental conditions deteriorates
Solution Approach 1:
The patent applies dynamics by making the duty ratios of the first and second heaters variable rather than fixed. The control unit dynamically adjusts the duty ratios based on detected temperatures at the center and end portions, paper size, and environmental conditions, allowing the heating system to adapt to different operating conditions while maintaining temperature uniformity.
Solution Approach 2:
The patent changes the heating parameters (duty ratios) based on multiple factors including paper size (A4, A3, B4, etc.), environmental temperature, and detected temperature differences. This allows the system to optimize heating for each specific condition, resolving the contradiction between simplified control and temperature uniformity.
2Ease of operation
If the duty ratio of the second heater is fixed based on the first heater's duty ratio, then the control process is simplified, but the ability to adapt to varying environmental conditions and paper sizes deteriorates
Solution Approach 1:
The patent stores multiple sets of duty ratio data in a storage unit, each set corresponding to different paper sizes and environmental conditions. The control unit selects and applies the appropriate duty ratio set based on detected conditions, providing both simplified control (through pre-stored data) and high adaptability (through multiple condition-specific sets).
Solution Approach 2:
The patent performs preliminary action by pre-calculating and storing optimal duty ratio combinations for various paper sizes and environmental conditions. This allows the control unit to quickly select the appropriate parameters without complex real-time calculations, maintaining simplicity while ensuring adaptability.
3Measurement precision
If multiple heater control patterns are used to maintain temperature gradients, then temperature control accuracy is improved, but the device complexity increases
Solution Approach 1:
The patent segments the heating control into two independent but coordinated parts: the first heater controlling the center portion and the second heater controlling the end portions. Each heater has its own duty ratio that can be independently adjusted based on temperature detection, allowing precise control of different regions while maintaining manageable system 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
This solution ensures more appropriate and reliable toner image fixation on paper sheets, preventing excessive temperature increases and maintaining image quality across different paper types and sizes, while reducing processing complexity and improving image formation consistency.
Implementation Method 1
a first heater (28a) that heats a center portion (31) of the fixing roller (26) in the longitudinal direction; a second heater (28b) that heats an end portion (33a) of the fixing roller (26) in the longitudinal direction
Implementation Method 2
a temperature sensor that detects the temperatures of the fixing roller (26)
Implementation Method 3
a control unit that determines an energization ratio of the first heater (28a) and the second heater (28b) such that the temperature detected by the temperature sensor becomes equal to a target temperature
Data Source
AI summary
An image forming apparatus includes a width-information acquisition unit, an environmental-condition detecting unit, a heat roller, an end-portion-temperature-detecting unit, a first heater, a second heater, a first control unit, a first control unit, a correction-value derivation unit, an extracting unit, and a second control unit. The first heater heats a center portion of the heat roller. The second heater heats the end portion of the heat roller. The first control unit controls electric power supplied to the first heater with a first duty ratio. The correction-value derivation unit derives a correction value for the temperature condition based on an environmental condition. The extracting unit reflects the correction value for the temperature condition to extract a second duty ratio from among a plurality of second duty ratios. The second control unit controls the electric power supplied to the second heater with the data of the extracted second duty ratio.