Fixing Device Heating Control to Suppress Fluorescent Lamp Flicker
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Solution Overview
Problem
Existing image forming apparatuses experience flickering of fluorescent lamps due to sharp fluctuations in alternating current power supply to the heater, which affects the fixing of toner images on recording media.
Innovation Solution
A fixing device with a controller that switches between first and second heating modes, initiating second heating before the recording medium enters the nip by a delay time and maintaining a duty cycle of less than 40%, using a combination of feedforward and feedback control to stabilize temperature and reduce flickering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the heater is supplied with power from an alternating current power supply to heat the rotator to target temperature, then the rotator can fix the toner image on the recording medium, but the alternating current voltage fluctuates sharply causing fluorescent lamps to flicker
Solution Approach 1:
The patent applies periodic action by switching between first heating (full power) and second heating (reduced power) in a cyclic manner. The controller alternates between these two heating modes to maintain the rotator temperature while reducing voltage fluctuations. This periodic switching smooths the power consumption profile, preventing sharp voltage spikes that cause fluorescent lamp flickering, while still achieving the required heating effect over time.
2Object-affected harmful factors
If the heater is controlled to switch between first heating and second heating to suppress flickering, then fluorescent lamp flickering is reduced, but the temperature control complexity increases
Solution Approach 1:
The patent employs feedback control where the controller monitors the rotator temperature and adjusts the heating mode accordingly. The temperature sensor provides real-time temperature data to the controller, which then determines whether to apply first heating or second heating. This feedback mechanism automates the temperature regulation process, managing the control complexity through intelligent algorithms rather than simple on-off control.
3Object-affected harmful factors
If the heater switches from first heating to second heating before the recording medium enters the nip, then voltage fluctuations are reduced, but the heating timing precision must be increased
Solution Approach 1:
The patent applies preliminary action by switching from first heating to second heating before the recording medium actually enters the nip region. This anticipatory switching occurs at a predetermined time point calculated based on the medium's position and the heater's thermal response characteristics. By acting in advance, the system smooths voltage fluctuations before they would occur during medium passage, while the predetermined timing ensures the rotator remains at the correct temperature when the medium arrives.
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 suppresses flickering and improves the fixing process, ensuring consistent image quality and glossiness on the recording medium.
Implementation Method 1
As the heater is supplied with power from an alternating current power supply, the heater generates heat, heating the rotator to a target temperature
Implementation Method 2
As the recording medium enters the nip formed between the rotators, the rotator heats the unfixed toner image on the recording medium, fixing the unfixed toner image on the recording medium
Data Source
AI summary
A fixing device includes a first rotator and a second rotator that form a nip therebetween and fix an image on a recording medium that enters the nip. A heater heats at least one of the first rotator or the second rotator. A controller controls the heater to switch between a first heating and a second heating, to switch from the first heating to the second heating before the recording medium enters the nip, to start the second heating at a time prior to a nip entry time at which the recording medium enters the nip by a delay time period taken for the heater to conduct heat to the nip, and to continue the first heating before the second heating for at least one control cycle at a duty cycle of power supplied to the heater. The duty cycle is not greater than 40%.