Fixing Unit Heater Control for Toner Image Overshooting
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Solution Overview
Problem
Electrophotographic image forming apparatuses face challenges in reducing overshooting during the warm-up process of the fixing unit, which can lead to excessive heating and hot offset, while also aiming to minimize first print out time (FPOT) by increasing the rate of temperature rise, but delayed entry of recording material can exacerbate overshooting.
Innovation Solution
The apparatus includes a control unit that adjusts the power supply to the heater to change the temperature gradient during the warm-up process based on the time from the start of power supply to the heater until the recording material enters the fixing nip portion, using distinct PID control parameters for warm-up and fixing processes to prevent overshooting and reduce FPOT.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the rate of temperature rise of the fixing unit is increased to reduce first print out time (FPOT), then FPOT is reduced, but overshooting occurs when entry timing of recording material is delayed
Solution Approach 1:
The patent applies dynamics by making the temperature gradient adjustable and variable during the warm-up process. The control unit dynamically changes the temperature gradient based on the actual entry timing of the recording material, transitioning from a fixed gradient approach to a flexible, adaptive one that optimizes both FPOT and overshooting control.
Solution Approach 2:
The patent implements parameter changes by modifying the temperature gradient parameter during warm-up based on recorded material entry timing. The control unit adjusts the heating power to maintain an appropriate temperature gradient, preventing overshooting while reducing FPOT through optimized temperature control parameters.
2Temperature
If different PID control parameters are used for warm-up and fixing processes, then overshooting is reduced, but the temperature gradient control flexibility is limited
Solution Approach 1:
The patent overcomes the limitation of fixed PID parameters by implementing a dynamic temperature gradient control system. The control unit continuously monitors and adjusts the heating power to maintain the appropriate temperature gradient during warm-up, providing flexibility to adapt to varying entry timing conditions rather than relying on predetermined fixed parameters.
Solution Approach 2:
The patent applies feedback by using the actual entry timing information of the recording material to adjust the temperature gradient during warm-up. The control unit receives feedback about when the recording material will enter the fixing unit and modifies the heating control accordingly, creating a closed-loop system that adapts to real-time conditions.
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 effectively reduces overshooting and minimizes FPOT by controlling the temperature gradient during the warm-up process, ensuring the fixing unit reaches the target temperature without excessive heating, thus preventing hot offset and improving print efficiency.
Implementation Method 1
power to be supplied to a heater mounted on the fixing unit is controlled so that a rate of temperature rise of the fixing unit becomes higher at the time of warm-up
Implementation Method 2
a fixing unit that heats and fix the toner image formed on the recording material to the recording material in a fixing nip portion
Data Source
AI summary
An image forming apparatus includes an image forming unit, a fixing unit, and a control unit. The image forming unit forms a toner image on a recording material. The fixing unit heats and fix the toner image formed on the recording material to the recording material in a fixing nip portion. The fixing unit includes a heater and a nip portion forming member that forms the fixing nip portion to pinch and convey the recording material. The control unit control the power to be supplied to the heater so as to change a temperature gradient at time of warm-up of the fixing unit to a target temperature in accordance with time from start of power supply to the heater until entry of the recording material into the fixing nip portion.