PTC Heating Resistor Control for Inrush Current Suppression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Image forming apparatuses using PTC materials for heaters face challenges in efficiently managing power consumption, as the resistance of PTC materials increases with temperature, leading to potential overconsumption at lower temperatures.
Innovation Solution
The image forming apparatus includes a control unit that adjusts the energization amount of the heating resistor based on its temperature, using a higher energization amount when the temperature is higher than a predetermined value and a lower amount when it is lower, thereby optimizing power usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a PTC material is used as a heating element, then safety and energy savings are obtained at high temperatures due to increased resistance, but more power than expected is consumed when the temperature is low
Solution Approach 1:
The patent applies dynamics by making the heating system adaptable through multi-stage control. The system transitions from a static PTC heater to a dynamic system that adjusts heating intensity based on temperature requirements, using different energization stages (first, second, and third energization amounts) to match the actual heating needs at different operational phases.
Solution Approach 2:
The patent changes the electrical parameter (energization amount) based on temperature parameters. By monitoring temperature and adjusting the energization amount accordingly, the system optimizes power consumption. The control unit switches between different resistance values and corresponding energization amounts to match the heating requirements at different temperature levels.
2Device complexity
If a PTC element is used for heating, then temperature control is simplified due to positive temperature coefficient, but inrush current occurs when the temperature is low
Solution Approach 1:
The patent applies preliminary action by implementing a staged heating approach. Before applying full power, the system first applies a lower first energization amount to gradually heat the PTC element. This preliminary heating phase prevents the sudden inrush current that would occur if full power were applied directly to a cold PTC element.
Solution Approach 2:
The patent uses periodic action through multi-stage energization control. The heating process is divided into distinct periods or stages: an initial stage with first energization amount, followed by a second stage with second energization amount, and potentially a third stage with third energization amount. This periodic adjustment of power levels smooths out current surges.
3Productivity
If high energization amount is applied to heat the PTC heater quickly, then heating efficiency is improved, but power consumption increases and flicker occurs
Solution Approach 1:
The patent applies partial action by using different energization amounts appropriate to different heating stages. Instead of continuously applying excessive high power, the system uses a moderate first energization amount initially, then transitions to a second energization amount as needed. This partial application of power achieves heating efficiency while avoiding unnecessary energy waste 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
This approach effectively suppresses maximum power consumption, preventing inrush current and reducing flicker, while ensuring the heating element reaches the required temperature efficiently.
Implementation Method 1
a conveyed sheet and developer are heated by a heater through the film
Implementation Method 2
A specific example of such a material is a positive temperature coefficient (PTC) material. A PTC material has a positive temperature coefficient of resistance (PTCR), i.e., the electrical resistance of the material increases as the temperature increases.
Data Source
AI summary
An image forming apparatus includes a fixing device and a control unit. The fixing device includes a heating resistor formed of a positive temperature coefficient material. The control unit energizes the heating resistor with a first energization amount if a temperature of the heating resistor is lower than a predetermined temperature, and energizes the heating resistor with a second energization amount that is higher than the first energization amount if the temperature of the heating resistor is higher than the predetermined temperature.