Heater Control Unit Detecting AC Voltage Drops via Power Ratio Analysis
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Solution Overview
Problem
Existing heating fixing apparatuses in image forming devices face challenges in detecting a drop in commercial AC power supply voltage without increasing circuit complexity or cost, which can lead to data loss during voltage drops.
Innovation Solution
A heating apparatus that includes a heat generating member, a temperature detection device, and a current detection device, with a control unit that detects voltage drops based on the maximum suppliable power ratio using the current and temperature data, allowing for controlled power supply adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a low input voltage protection circuit is used to detect AC power supply voltage drops, then the reliability of the heating apparatus is improved, but the device complexity and cost increase due to additional circuits
Solution Approach 1:
The control unit performs multiple functions: it controls the heater based on temperature feedback and simultaneously detects AC power supply voltage drops by analyzing the relationship between commanded power ratio and actual power ratio. This eliminates the need for separate voltage detection circuits while maintaining reliable voltage drop detection capability.
Solution Approach 2:
The system uses its own existing sensors (temperature detection device) and control parameters (power ratio commands and actual power ratios) to detect voltage drops. The control unit leverages data already being collected for temperature control purposes, making the voltage detection self-service rather than requiring external dedicated circuits.
2Reliability
If the low input voltage protection circuit stops power supply when voltage drops, then the reliability is improved, but data loss occurs during writing operations
Solution Approach 1:
The control unit detects voltage drops in advance by monitoring the discrepancy between commanded and actual power ratios before the protection circuit activates. This early detection allows the system to initiate data protection procedures (stopping writing operations) before power supply is interrupted, preventing data loss while maintaining reliable voltage drop protection.
Solution Approach 2:
The system uses feedback from the power ratio comparison to detect voltage drops. By continuously monitoring whether the actual power ratio matches the commanded power ratio, the control unit can identify voltage drop conditions and respond appropriately, enabling timely data protection actions.
3Measurement precision
If phase control or wave number control is used for the ceramic heater, then the temperature control precision is improved, but the device complexity increases
Solution Approach 1:
The system employs feedback control where the control unit continuously compares the actual temperature (from the temperature detection device) with the target temperature and adjusts the power ratio command accordingly. This feedback mechanism enables precise temperature control using phase control or wave number control of the AC power supply without requiring overly complex control mechanisms.
Solution Approach 2:
The control unit adjusts the power ratio parameter (phase angle or wave number) to control the heater power. By manipulating this single parameter based on temperature feedback, the system achieves precise temperature control while keeping the control mechanism relatively simple, avoiding the need for multiple independent control systems.
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
Enables detection of input voltage drops without additional circuits, preventing data loss by stopping writing operations before power supply shutdown, thus maintaining data integrity and reducing costs.
Implementation Method 1
a heat generating member which generates heat when power is supplied from an AC power supply
Implementation Method 2
a temperature detection device which detects temperature of the heat generating member
Implementation Method 3
a current detection device which detects a value of current flowing in the heat generating member
Data Source
AI summary
The heating apparatus includes a heat generating member which generates heat when power is supplied from an AC power supply, a temperature detection device which detects temperature of the heat generating member, a current detection device which detects a value of current flowing in the heat generating member; and a control unit which controls the temperature of the heat generating member by controlling power supplied to the heat generating member, in which the control unit detects a drop of an input voltage of the AC power supply based on a maximum suppliable power ratio determined by using a value of current suppliable to the heat generating member, the current value detected by the current detection device, and a ratio of power supplied to the heat generating member obtained based on the temperature detected by the temperature detection device.