Image Forming Heater Timing for High-Voltage Protection
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Solution Overview
Problem
Heaters in fixing devices of image forming apparatuses can be damaged by high voltages exceeding product ratings, leading to reduced printing efficiency as the machine becomes unusable.
Innovation Solution
An image forming apparatus with a voltage measuring unit, control unit, and zero crossing detection circuit determines a heating timing for the heater based on measured voltage, controlling its activation to avoid damage during high voltage input, and employs protection controls to reduce printing efficiency temporarily.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the heating unit is protected by making the machine unusable when high voltage is detected, then the heater is protected from damage, but the printing efficiency decreases
Solution Approach 1:
The system dynamically adjusts the heating control strategy based on detected voltage conditions. During high voltage periods, the heating unit is controlled to operate only during specific time windows when voltage returns to normal levels, rather than being completely disabled. This dynamic adaptation allows the system to maintain printing functionality while protecting the heater from damage.
Solution Approach 2:
The control system changes the operational parameters of the heating unit based on voltage measurements. When high voltage is detected, the system modifies heating timing, duration, and intensity parameters to operate within safe voltage conditions, rather than maintaining fixed operational parameters that would cause damage during high voltage events.
2Productivity
If the heating unit operates continuously during high voltage input, then the printing efficiency is maintained, but the heater may be damaged
Solution Approach 1:
The system continuously monitors voltage levels and uses this feedback to control the heating unit operation. When high voltage is detected, the feedback loop automatically adjusts or suspends heating operations to prevent damage. This closed-loop control ensures the heating unit operates only when voltage conditions are safe, preventing damage while maintaining printing efficiency when possible.
Solution Approach 2:
The system performs preliminary voltage detection before activating the heating unit. By checking voltage levels in advance and predicting potentially harmful high voltage conditions, the system can prevent damage by avoiding heater activation during unsafe conditions, rather than waiting for damage to occur and then responding.
3Reliability
If protection controls are implemented to reduce printing efficiency temporarily, then the heater is protected from damage, but the overall printing output decreases
Solution Approach 1:
The system implements periodic voltage monitoring and uses this information to determine appropriate heating control actions. Rather than continuous suspension of heating operations, the system periodically checks voltage conditions and resumes normal operation when safe conditions return, creating a rhythm of protected operation that minimizes impact on overall printing output while ensuring heater safety.
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 apparatus prevents heater damage while maintaining printing operations, reducing efficiency impacts, and avoids costly full protection measures, thus enhancing convenience and cost-effectiveness.
Implementation Method 1
a voltage measuring unit that measures an input voltage
Implementation Method 2
a zero crossing detection circuit that detects a zero crossing point of an AC voltage
Implementation Method 3
The fixing device includes a heating unit that heats the sheet
Data Source
AI summary
According to at least one embodiment, an image forming apparatus includes a heater and a controller. The heater is configured to generate heat. The controller is configured to control AC power to the heater so that a part of the AC power which exceeds a threshold voltage is not applied to the heater.