Heater Control Phase Shift Harmonic Suppression
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Solution Overview
Problem
Conventional phase control methods for heater control devices in fixing devices lead to the generation of harmonic currents, which affect other electric devices and fail to balance flicker suppression with conformity to harmonic current standards.
Innovation Solution
A heater control device that performs phase control by gradually increasing the on-duty ratio, with different increment amounts based on whether the on-duty ratio is within or outside a predetermined range including 50%, to suppress harmonic currents and ensure compliance with harmonic current standards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If phase control is performed by switching on and off power supply within each half-cycle of AC power, then inrush current and flicker are suppressed, but harmonic currents are generated on the power supply line
Solution Approach 1:
The patent segments the phase control process into two distinct phases: a first phase control period where the on-duty ratio is increased by a first amount (suppressing harmonic currents), and a second phase control period where the on-duty ratio is increased by a second amount (suppressing inrush current and flicker). This segmentation allows each phase to address different harmful effects independently.
Solution Approach 2:
The patent implements periodic action by alternating between two different control modes during the warm-up period. The control unit switches between the first phase control (with first amount increase) and second phase control (with second amount increase) based on the current on-duty ratio and target power amount, creating a periodic control pattern that addresses both harmonic current and flicker issues.
2Object-affected harmful factors
If the on-duty ratio is increased by a small fixed amount for each hertz in phase control, then flicker generation is suppressed, but the through-up time to supply target power amount increases
Solution Approach 1:
The patent applies dynamics by making the increment amount of the on-duty ratio variable rather than fixed. The control unit dynamically adjusts the increment amount based on the current operational phase (first phase control or second phase control) and the relationship between the current on-duty ratio and the target power amount, optimizing both flicker suppression and through-up time.
Solution Approach 2:
The patent changes the parameter of on-duty ratio increment amount from a fixed value to a variable value that depends on the control phase. By switching between first amount (smaller increment) and second amount (larger increment) based on operational conditions, the system optimizes the balance between suppressing flicker and reducing through-up time.
3Loss of time
If the on-duty ratio is increased by a large fixed amount for each hertz in phase control, then the through-up time is reduced, but inrush current increases and flicker cannot be suppressed
Solution Approach 1:
The patent uses dynamics to adjust the on-duty ratio increment amount based on real-time operational conditions. During the first phase control, a smaller increment (first amount) is used to suppress inrush current and flicker. During the second phase control, a larger increment (second amount) is used to reduce through-up time, creating a dynamic adaptation to different operational requirements.
Solution Approach 2:
The patent changes the increment parameter of the on-duty ratio from a constant large value to a conditional variable. By switching between first amount and second amount based on the control phase and power supply status, the system achieves parameter optimization that reduces through-up time while preventing excessive inrush current and flicker.
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 reduces the time harmonic currents are generated at high values, thereby improving the balance between flicker suppression and harmonic current standard compliance.
Implementation Method 1
performing phase control of alternating power (hereinafter referred to as 'AC' power) supplied from a commercial AC power source and supplying phase-controlled power to a heater
Implementation Method 2
As a heater for heating toner transferred onto a recording sheet, such a fixing device includes, for instance, a halogen lamp or a resistance heating element
Data Source
AI summary
A heater control device that performs phase control of AC power and supplies phase-controlled power to a heater, the heater control device including: a control unit configured to, in the phase control, gradually increase an on-duty ratio until a target power amount is supplied to the heater; and a judgment unit configured to judge whether or not the on-duty ratio is within a predetermined range of on-duty ratios including a 50% on-duty ratio. The control unit (i) increases the on-duty ratio by a first amount while the on-duty ratio is within the predetermined range, and (ii) increases the on-duty ratio by a second amount while the on-duty ratio is not within the predetermined range. The first amount is greater than the second amount.