Halogen Lamp Heater Duty Cycle Control for Image Fixing
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Solution Overview
Problem
The life of halogen lamp heaters in image forming apparatuses is shortened due to chemical attack caused by continuous application of drive voltage with low duty cycles, especially when forming images on small sheets, leading to filament erosion.
Innovation Solution
The apparatus includes multiple halogen lamp heaters with different distributions, an AC power supply, and a processor that adjusts the duty cycle of the drive voltage based on temperature readings, switching between heaters to maintain optimal operating conditions and prevent prolonged low-duty-cycle exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If drive voltage is applied continuously with low duty cycle to halogen lamp heater, then heat requirement is met for small sheet imaging, but filament erosion occurs due to chemical attack
Solution Approach 1:
The patent implements periodic action by alternating between two or more halogen lamp heaters in a cyclic manner. Instead of continuously operating a single heater at low duty cycle, the system switches between multiple heaters, allowing each to undergo periods of operation and rest. This periodic operation prevents continuous chemical attack on any single filament, thereby extending heater life while maintaining the ability to provide necessary heat for small sheet imaging.
Solution Approach 2:
The patent applies the discarding and recovering principle by temporarily discontinuing use of a halogen lamp heater after a predetermined period of continuous low-duty-cycle operation, then switching to an alternative heater. This allows the first heater to recover from chemical attack conditions, preventing permanent filament erosion. The system recovers heater life by periodically taking heaters out of service and switching to backups.
2Reliability
If duty cycle is increased to prevent chemical attack, then heater life is extended, but heat distribution uniformity deteriorates
Solution Approach 1:
The patent applies segmentation by dividing the heating function into multiple halogen lamp heaters with different spatial distributions (e.g., center-distributed, side-distributed, overall-distributed). Each heater is responsible for heating specific regions of the fixing member. By segmenting the heating task across multiple specialized heaters and alternating their use, the system maintains heat distribution uniformity while preventing any single heater from suffering continuous chemical attack.
Solution Approach 2:
The patent implements local quality by using halogen lamp heaters with different distributions tailored to specific heating zones. The center-distributed heater targets the center area, side-distributed heaters target side areas, and overall-distributed heaters cover the entire area. This localized heating approach ensures that each region receives appropriate heat while the system alternates between heaters to prevent chemical attack, maintaining both heater life and heat uniformity.
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 life of halogen lamp heaters by preventing chemical attack and ensuring consistent heat distribution across various sheet sizes, maintaining filament integrity and reducing maintenance needs.
Implementation Method 1
halogen lamp heaters 186 to 188 each of which is constituted by a fixing lamp (or fixing heater) extending along the rotation axis of the fixing roller 183
Implementation Method 2
a temperature detector 185 which detects a temperature of the fixing roller 183
Data Source
AI summary
An image forming apparatus includes a processor and heaters which heat a fixing member of an image fixing device. The processor calculates an application pattern for the heaters based on a temperature of the fixing member and generates a drive voltage by suitably selecting half waves from an AC waveform of an AC power supply according to the application pattern. When a duration of time the drive voltage is applied to a first heater in the application pattern having a duty cycle of a predetermined level or less exceeds a predetermined period of time, (i) the processor turns off the first heater and turns on a second heater with a different distribution, or (ii) the processor increases the duty cycle of the first heater and decreases a duty cycle of the second heater.