Heating Lamp Power Control for Flickering Reduction
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Solution Overview
Problem
Conventional fixing circuits for laser printers and photocopiers experience irregular power control, leading to flickering and increased inrush current during initial warm-up, which results in prolonged heating times and pronounced flickering of display devices.
Innovation Solution
An apparatus and method that include a voltage detector, synch signal generator, and controller using table information of temporal duty level values to control the switching of input power to heating lamps, allowing for gradual power increase and minimizing initial heating time while reducing flickering and harmonic characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If high power is supplied to the fixing unit during initial warm-up to reduce heating time, then the instantaneous heating time is reduced, but inrush current increases causing pronounced flickering and harmonic characteristics in display devices
Solution Approach 1:
The patent applies periodic action by controlling the triac switching unit to supply power in periodic cycles with varying duty levels. During initial warm-up, the controller uses table information to output control signals that gradually increase power supply in controlled periodic intervals, avoiding instantaneous high power while still achieving heating within acceptable timeframes, thus reducing both heating time and harmful flickering effects
Solution Approach 2:
The patent implements parameter changes by dynamically adjusting the duty level of AC power supplied to the fixing unit. The controller references table information containing temporal duty level values to modify power parameters progressively during warm-up, rather than maintaining constant high power. This parameter modulation reduces inrush current and associated flickering while achieving necessary heating
2Device complexity
If the controller simply controls the triac switching unit without voltage synchronization information, then the control circuit is simple, but irregular turn-on timing causes flickering of display devices
Solution Approach 1:
The patent implements feedback by introducing a voltage detector that monitors the AC input voltage and provides synchronization information to the controller. This feedback mechanism enables the controller to adjust triac switching timing based on actual voltage conditions, ensuring regular turn-on timing that prevents display flickering while maintaining relatively simple circuit architecture
Solution Approach 2:
The patent uses an intermediary approach by introducing a voltage detector as a mediator between the AC power source and the triac switching unit. The voltage detector provides synchronization signals that enable coordinated switching, eliminating irregular turn-on timing and associated flickering without requiring complex control circuitry
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 instantaneous heating time and minimizes flickering and harmonic characteristics of display devices by gradually increasing power supply to heating lamps, optimizing the initial heating process.
Implementation Method 1
a voltage detector for detecting a voltage of an input power supplied to heat at least one heating lamp
Implementation Method 2
detecting a voltage of an input power supplied to heat at least one heating lamp
Data Source
AI summary
An apparatus and method for controlling the power supplied to a fixing unit are provided. The apparatus includes a voltage detector detecting a voltage of input power supplied to heat at least one heating lamp, a synch signal generator generating a synch signal in response to the detected voltage, a switching unit switching a supply path of the input power to be applied to the at least one heating lamp, and a controller having table information of temporal duty level values of the input power that is initially supplied, and outputting a control signal for controlling a switching operation of the switching unit using the generated synch signal and the table information, wherein the switching unit performs the switching operation corresponding to the control signal. Accordingly, by sequentially increasing the input power for initial heating of the heating lamps, flickering and harmonic characteristics of a display device can be reduced, and by setting the duty level values to supply the maximum input power within a certain time, an initial heating time of the heating lamps can be minimized.