Induction Heating Fixing Unit Noise Control via Cyclic Waveform
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Solution Overview
Problem
Existing induction heating type fixing units in image forming apparatuses face challenges in controlling heating values with a simple configuration, often resulting in unwanted noise and vibration issues due to specific frequency components in the drive voltage, which can affect image quality.
Innovation Solution
A fixing unit with a tubular rotary member and a magnetic core, where a controller adjusts the output of a cyclic waveform to control the heating value, avoiding specific frequency components by changing the pulse cycle and pause periods, thereby preventing unwanted noise and vibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a step-down converter is used to control the heating value, then the heating value can be controlled, but the device complexity and cost increase
Solution Approach 1:
The patent extracts the problematic step-down converter from the system and replaces it with a simpler pulse width modulation approach using existing converter device circuitry, eliminating unnecessary components while maintaining heating control capability
Solution Approach 2:
The existing converter device is made to perform dual functions: both voltage conversion and heating value control through pulse width modulation, eliminating the need for separate control circuitry and reducing overall system complexity
2Device complexity
If pulse width modulation is used to control heating value, then the configuration is simplified, but mosquito sound and vibration occur due to specific frequency components
Solution Approach 1:
The patent employs periodic pulse width modulation with carefully selected pulse cycles and pause periods that avoid resonant frequencies of the rotary member, thereby eliminating mosquito sound and vibration while maintaining effective heating control
Solution Approach 2:
The patent dynamically adjusts pulse cycle and pause period parameters based on the rotary member's operational state, changing the frequency characteristics of the drive voltage to avoid specific frequency components that cause noise and vibration
3Power
If the pulse cycle is shortened to increase heating value, then the heating efficiency improves, but high frequency components cause noise and vibration
Solution Approach 1:
The patent uses periodic pulsing with optimized duty cycles and pause periods that deliver sufficient heating power while keeping the fundamental frequency and its harmonics away from the rotary member's resonant frequencies, thus avoiding noise and vibration
Solution Approach 2:
The patent dynamically adjusts the pulse cycle and pause period based on real-time heating requirements and rotary member state, allowing flexible optimization of both heating efficiency and noise reduction under different operating 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 solution allows for effective control of heating values with a simple configuration, reducing noise and vibration, and maintaining desired heat generation distributions, thus enhancing image quality.
Implementation Method 1
The induction heating type fixing unit generates an alternating magnetic field by applying an AC voltage to a coil, and heats a rotary member having a conductive layer according to the electromagnetic induction principle
Implementation Method 2
heats a rotary member having a conductive layer according to the electromagnetic induction principle
Implementation Method 3
The controller causes the converter device to output a cyclic waveform in which a first waveform and a second waveform appear... such that the conductive layer is heated by induction heating
Data Source
AI summary
A fixing unit includes a rotary member, a magnetic core, a coil, a converter device, a temperature detection unit, and a controller. A conductive layer of the rotary member is heated by induction heating. The controller causes the converter device to output a cyclic waveform in which a first waveform and a second waveform appear. The first waveform is a waveform in which pulses having a constant cycle are successively output for a first output period and output of the pulses is paused for a first pause period after the first output period. The second waveform is a waveform in which the first waveform is repeatedly output for a second output period and output of the first waveform is paused for a second pause period after the second output period. The cyclic waveform is a waveform in which the second waveform is cyclically repeated as a repetition unit.