Fusing Unit Current-Feed Controller Harmonic Reduction
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Solution Overview
Problem
Conventional techniques for reducing harmonic current in image forming apparatuses, particularly in fusing units, are insufficient in meeting stricter standards while maintaining temperature stability, especially during the heating control process.
Innovation Solution
An image forming apparatus with a current-feed controller that adjusts the current-feed ratio dynamically using a switching circuit and temperature detector to maintain target temperature ranges, and executes specific current-feed modes based on the position of the recording medium, fixing the duty ratio to almost 100% or 0% during certain phases to minimize harmonic current and temperature instability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If conventional sine-wave AC switching technique is used to reduce high frequency wave, then high frequency wave occurrence is reduced, but harmonic current standards are not met under stricter requirements
Solution Approach 1:
The patent applies dynamics by making the current feed ratio adjustable and variable over time. The control unit dynamically changes the current feed ratio to almost 100% or almost 0% at specific timing (when the end of recording medium is detected at the fusing position) rather than maintaining a fixed switching pattern. This dynamic adjustment allows the system to adapt to different operational conditions and meet stricter harmonic current standards while maintaining temperature stability.
Solution Approach 2:
The patent changes the parameter of current feed ratio from a conventional fixed switching pattern to a variable parameter that can be adjusted to almost 100% or almost 0%. By changing this key parameter at specific timing based on recording medium position, the system achieves better harmonic current compliance while maintaining effective heating control.
2Measurement precision
If current feed is frequently switched on/off to control heater temperature, then temperature control precision is improved, but temperature instability occurs
Solution Approach 1:
The patent applies preliminary action by detecting the position of the recording medium end at the fusing position in advance and proactively adjusting the current feed ratio to almost 100% or almost 0% before temperature instability can occur. This preventive measure allows the system to maintain temperature stability by anticipating and counteracting potential temperature fluctuations before they affect the fusing process.
3Object-generated harmful factors
If harmonic current is reduced by adjusting current switching, then compliance with standards is improved, but heating efficiency may deteriorate
Solution Approach 1:
The patent applies periodic action by implementing regular position-based control cycles. The control unit periodically detects the position of the recording medium end and adjusts the current feed ratio in a systematic periodic manner. This periodic adjustment strategy ensures that harmonic current is reduced while maintaining heating efficiency, as the system follows a predetermined optimal control pattern that balances both requirements.
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
Effectively reduces harmonic current and stabilizes the temperature of the fusing unit, preventing overheating and thermal runaway, while adhering to stricter harmonic current standards.
Implementation Method 1
a fusing unit including a heater that receives electric power from an AC power source
Data Source
AI summary
An image forming apparatus includes a fusing unit configured to fuse an image formed on a recording medium to a recording medium, at a fusing position where a heater and a rotator nip the recording medium therebetween, and a current-feed controller configured to execute a first current-feed mode of changing a current-feed ratio of current-feed time from an AC power source to the heater to unit time by controlling switching of a switching circuit so that a temperature detected by a temperature detector falls within a target range. The current-feed controller executes a second current-feed mode of fixing the current-feed ratio to almost 100% or almost 0% in place of the first current-feed mode based on a timing when a position detector detects that an end of the recording medium in a conveying direction is located at the fusing position.