Power Supply Apparatus for Heat Fixing with Transformer-Based Detection
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Solution Overview
Problem
Existing power supply apparatuses for heat fixing devices in image forming equipment face challenges in accurately controlling and detecting power supply, leading to inefficiencies in shortening the First Print Out Time (FPOT) due to errors in power duty and variations in heating resistor temperatures.
Innovation Solution
A power supply apparatus with a configuration that includes a voltage detection device, current detection unit, zero-crossing detection unit, voltage calculation unit, power calculation unit, and a control unit, which accurately calculates and corrects the power supplied to the heat fixing device by using transformers and switching units to manage AC power supply effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If power supply control is simplified using conventional methods, then device complexity is reduced, but measurement precision of power supplied to heat fixing device deteriorates
Solution Approach 1:
The patent introduces intermediary components (transformers T1 and T2, current converters) that mediate between the AC power supply and the control system. These intermediaries enable accurate measurement of voltage and current without requiring the control unit to directly interface with high-power circuits, thus maintaining measurement precision while keeping the control structure manageable.
Solution Approach 2:
The patent replaces direct electrical measurement methods with transformer-based measurement systems. Instead of using complex power monitoring circuits that would increase device complexity, the system uses electromagnetic transformation to convert power measurements into measurable voltage and current signals, achieving accurate power detection through physical field transformation rather than complex electronic circuits.
2Productivity
If power detection accuracy is improved through detailed monitoring, then productivity in shortening FPOT is enhanced, but device complexity increases
Solution Approach 1:
The patent segments the power detection function into separate voltage detection and current detection units, each with dedicated transformers and processing circuits. This segmentation allows each unit to be optimized for its specific function, improving overall measurement accuracy for power calculation while keeping each individual unit relatively simple and maintainable.
Solution Approach 2:
The patent implements a feedback mechanism where the control unit continuously monitors voltage and current, calculates actual power consumption, compares it with target values, and adjusts power supply accordingly. This feedback loop enables precise control of heating power to achieve accurate temperature control and shortened FPOT, while the automated nature of the feedback reduces the need for complex manual intervention systems.
3Device complexity
If conventional power detection methods are used, then device complexity is minimized, but reliability of power control for heat fixing deteriorates
Solution Approach 1:
The patent uses transformers as intermediary devices that electrically isolate the measurement circuit from the high-power heating circuit. This isolation improves reliability by preventing measurement errors from affecting the heating control and by protecting the control system from voltage spikes and electrical noise generated by the heating element, while maintaining system simplicity through standard isolated measurement techniques.
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 enables precise detection and control of power supplied to the heat fixing device, reducing errors and ensuring appropriate power duty, thereby shortening FPOT without causing fixing failures and improving image formation efficiency.
Implementation Method 1
a first transformer (T1) including a primary winding and a secondary winding, the voltage detection device configured to detect an AC voltage based on a signal indicating the AC voltage output from the secondary winding of the first transformer by supplying the current converted by the conversion element to the primary winding
Implementation Method 2
a current detection unit including a second transformer (T2) having a primary winding and a secondary winding, the current detection unit configured to detect a current value of a current supplied to a first load included in the load based on a signal indicating an AC voltage output to a secondary side of the second transformer according to the current by supplying the current to the primary winding
Data Source
AI summary
The power supply apparatus configured to supply power to a load includes a control unit that corrects a power amount calculated by a power calculation unit based on a first voltage of an AC power supply calculated by a voltage calculation unit when the power amount is calculated, and a second voltage of the AC power supply calculated by the voltage calculation unit when a switching unit is controlled to start power supply to a power supply and a first transformer from the AC power supply.