Fixing Device Series Heater Circuit Simplification
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Solution Overview
Problem
Conventional fixing devices with multiple heaters connected in parallel require a temperature sensor for each heater, making the internal circuit complex and prone to overheating due to potential short-circuits, which complicates temperature control.
Innovation Solution
The heaters are connected in series with a single temperature sensor for each heater, allowing for simplified internal circuitry and effective temperature control by using a first temperature sensor to measure the central heater and an end temperature sensor to monitor the end heaters, preventing overheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple heaters are connected in parallel with individual temperature sensors, then each heater can be independently controlled, but the internal circuit becomes complex and the number of temperature sensors increases
Solution Approach 1:
The patent merges multiple temperature sensors into a single temperature sensor that measures the temperature of the fixing belt. This single sensor replaces multiple individual heater temperature sensors, simplifying the internal circuit while maintaining temperature control reliability through feedback control of the heater assembly.
Solution Approach 2:
The single temperature sensor serves a universal function by monitoring the temperature of the fixing belt that is heated by multiple heaters working together. This multi-functional approach allows one sensor to provide temperature feedback for the entire heating system rather than requiring dedicated sensors for each heater.
2Reliability
If multiple temperature sensors are provided for each heater, then overheating can be detected, but the device complexity and cost increase
Solution Approach 1:
The patent combines multiple temperature sensing functions into a single temperature sensor that monitors the fixing belt temperature. This single sensor provides overheating detection for the entire heating system, reducing the number of sensors from multiple to one while maintaining safety.
Solution Approach 2:
The fixing belt acts as an intermediary that transfers heat from multiple heaters to a single temperature sensor. The sensor measures the temperature of the fixing belt, which indirectly monitors the temperature of all heaters, providing a simplified overheating detection mechanism.
3Ease of manufacture
If heaters are connected in parallel, then power distribution is simplified, but temperature control becomes less precise and overheating risk increases
Solution Approach 1:
The patent implements feedback control by connecting the single temperature sensor to the controller, which adjusts the power supply to the heater assembly based on the measured fixing belt temperature. This feedback mechanism enables precise temperature control despite the parallel connection of multiple heaters.
Solution Approach 2:
The patent changes the control parameter from individual heater temperatures to the overall fixing belt temperature. By controlling the total power supplied to the heater assembly based on the single temperature sensor reading, the system achieves precise temperature control through parameter transformation rather than individual heater control.
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 configuration reduces the number of temperature sensors needed and simplifies the internal circuit, effectively preventing overheating by using a single end temperature sensor to monitor and control the end heaters, ensuring efficient heat distribution and fixing performance.
Implementation Method 1
The heating part is provided in an inner space of the heated member and heating an inner circumferential face of the heated member
Implementation Method 2
the heat is transferred from the nip area to the pressing roller through the fixing belt, and the pressing roller is also heated
Data Source
AI summary
The fixing device includes a cylindrical heated member and a heating part. The cylindrical heated member is long in a width direction of a sheet, and is supported in a rotatable manner with coming into contact with a fixing face of the sheet. The heating part is provided in an inner space of the heated member and heating an inner circumferential face of the heated member. The heating part includes a plurality of heaters disposed side by side in a longitudinal direction of the heated member; and a first temperature sensor measuring a first heater of the plurality of heaters or a heated area of the heated member heated by the first heater. The plurality of heaters and the first temperature sensor are connected in series by a first power supply line.