Halogen Lamp Heater Control for Fixing Roller Temperature
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Solution Overview
Problem
In image forming apparatuses, halogen lamp heaters face issues with temperature stabilization and filament degradation due to inadequate heat control, particularly when handling thin papers, leading to inefficient heat management and reduced heater lifespan.
Innovation Solution
The implementation of a control unit that manages a plurality of halogen lamp heaters with the same light distribution, using an AC power supply to apply a drive voltage with a half-wave AC waveform and a predetermined duty cycle, allowing for precise heat amount adjustment to prevent filament degradation and maintain temperature stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If the duty cycle of the application pattern is limited to a predetermined value or more to prevent chemical attack, then the lifespan of the halogen lamp heater is extended, but the heater cannot be turned off at appropriate timing to match the required heat amount, resulting in unstable fixing roller temperature
Solution Approach 1:
The fixing device is divided into a plurality of halogen lamp heaters (first halogen lamp heater and second halogen lamp heater) with different heat generation capacities. This segmentation allows the control unit to select appropriate heater combinations based on required heat amounts, enabling both lifespan extension through minimum duty cycle control and temperature stability through precise heat matching.
Solution Approach 2:
The control unit dynamically selects which halogen lamp heater to operate based on the required heat amount. When the required heat amount is small, the second halogen lamp heater (with lower heat generation) is selected to operate at minimum duty cycle, preventing chemical attack while matching the heat requirement. When the required heat amount is large, the first halogen lamp heater (with higher heat generation) is selected. This dynamic selection resolves the contradiction between extending lifespan and maintaining temperature stability.
2Use of energy by moving object
If the number of selected half-waves of AC waveform is small to reduce heat amount for thin paper, then the heat amount matches the requirement, but the effective value of drive voltage becomes smaller than reference voltage, causing chemical attack on the filament
Solution Approach 1:
The halogen lamp heater is segmented into two versions with different power ratings (first halogen lamp heater with higher power, second halogen lamp heater with lower power). This allows the system to select the second halogen lamp heater for thin paper processing, where it can operate at minimum duty cycle (preventing chemical attack) while still providing sufficient heat, thus resolving the contradiction between energy efficiency and filament reliability.
Solution Approach 2:
The system changes the parameter of heater power rating by selecting different halogen lamp heaters based on the required heat amount. For thin paper with small heat requirements, the second halogen lamp heater (lower power rating) is selected, allowing operation at minimum duty cycle that prevents chemical attack while maintaining filament integrity. This parameter change resolves the contradiction between efficient heat usage and filament protection.
3Productivity
If the heater is turned off at appropriate timing to match the required heat amount, then the heat amount efficiency is improved, but the temperature control cannot stabilize the fixing roller temperature
Solution Approach 1:
By segmenting the heater into two halogen lamp heaters with different heat generation capacities, the system can select the appropriate heater based on the required heat amount. This allows continuous heat amount adjustment without frequent on/off cycling, improving heat efficiency while maintaining temperature stability through sustained heater operation at minimum duty cycle.
Solution Approach 2:
The invention maintains continuous useful action by keeping the selected halogen lamp heater operating at minimum duty cycle rather than turning it off and on frequently. This continuous operation at minimum duty cycle both prevents chemical attack (by maintaining reference voltage) and stabilizes temperature (by avoiding temperature fluctuations from frequent shutdowns), while still matching the required heat amount through heater selection.
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 extends the lifespan of halogen lamp heaters and stabilizes the temperature of the fixing roller by ensuring the heat amount generated is sufficient for image forming while preventing filament breakdown, even when handling thin papers.
Implementation Method 1
a halogen lamp heater which generates a heat amount being a minimum heat amount required for fixing or less when turned on with the application pattern having the duty cycle of the predetermined value
Implementation Method 2
there is a reference voltage with which halogen cycle occurs most efficiently. If the number of selected half-waves (i.e., the selected number of half-waves) of the AC waveform is small, and hence the effective value of drive voltage to be supplied to a halogen lamp heater is smaller than the reference voltage, the temperature of a filament (tungsten) of the halogen lamp heater becomes low, and a phenomenon that the filament is eaten away, called 'chemical attack', occurs
Data Source
AI summary
An image forming apparatus includes halogen lamp heaters, an AC power supply, a temperature detection unit and a control unit. The heaters have a same light distribution and heat a fixing member of an image fixing unit. The detection unit detects a temperature of the fixing member. The control unit determines a combination of the heaters based on output of the detection unit and applies a drive voltage of a half-wave of an AC waveform of the AC power supply to a heater of the heaters. The half-wave is selected based on an application pattern having a duty cycle of a predetermined value or more. The heaters include at least one heater which generates a heat amount being a minimum heat amount required for fixing or less when turned on with the application pattern having the duty cycle of the predetermined value.