Fixing Heater Relay Segmentation for Power Shut-off Reliability
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Solution Overview
Problem
Image forming apparatuses with multiple fixing heaters face challenges in preventing abnormal heat generation due to relay failures, which can lead to safety issues and the inability to shut off power supply effectively.
Innovation Solution
The apparatus employs a configuration with two relays in each power feeding path for the fixing heaters, allowing for independent control of AC power supply through triacs and relays to ensure safe shut-off in case of relay failures, using a first relay for neutral and a second relay for hot power lines to prevent abnormal heat generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a relay having a plurality of contacts is used to save space in the substrate, then the area occupied by relays is reduced, but the reliability of power shut-off is compromised due to potential relay drive circuit failures
Solution Approach 1:
The patent divides the power feeding paths into multiple independent segments, each controlled by a separate relay. Specifically, the hot power feeding line is controlled by a first relay and the neutral power feeding line is controlled by a second relay. This segmentation ensures that even if one relay fails, the other relay can still shut off power to the fixing heaters, thereby maintaining power shut-off reliability while using multiple relays on the substrate.
Solution Approach 2:
The patent implements a redundant relay configuration as a preventive measure against relay failures. By providing two independent relays (first relay for hot line, second relay for neutral line) instead of relying on a single multi-contact relay, the system cushions against the potential failure of one relay drive circuit. This beforehand cushioning ensures that power can still be shut off reliably even if one relay fails.
2Productivity
If multiple fixing heaters are used to increase productivity, then the heat generation capability is improved, but the risk of abnormal heat generation due to control errors increases
Solution Approach 1:
The patent segments the power supply control for multiple fixing heaters by implementing independent relay control for hot and neutral power feeding lines. Each fixing heater can be controlled independently through this segmented approach, allowing precise temperature management and reducing the risk of abnormal heat generation while maintaining high productivity through multiple heaters operating simultaneously.
Solution Approach 2:
The patent incorporates temperature detection means that continuously monitors the temperature of fixing heaters and provides feedback to the control system. This feedback mechanism allows the system to adjust power supply in real-time, preventing abnormal heat generation while maintaining the high productivity enabled by multiple fixing heaters operating at optimal temperatures.
3Reliability
If one relay is provided in every power feeding path from hot and neutral power feeding lines, then the configuration complexity increases, but the reliability of individual path control is improved
Solution Approach 1:
The patent applies segmentation by assigning separate relays to different power feeding paths: the first relay controls the hot power feeding line and the second relay controls the neutral power feeding line. This segmentation improves individual path control reliability by isolating control functions, while the systematic arrangement of these relays on the substrate minimizes the increase in overall configuration complexity.
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 effectively prevents abnormal heat generation by ensuring reliable shut-off of AC power to the fixing heaters even in case of relay failures, enhancing safety and reliability compared to previous designs.
Implementation Method 1
a first relay configured to be switched between a first state in which electric connection is established and a second state in which electric connection is not established; and a second relay configured to be switched between a third state in which electric connection is established and a fourth state in which electric connection is not established
Implementation Method 2
a first fixing heater and a second fixing heater which are configured to generate heat, the fixing device being configured to heat the image on the recording material by using the first fixing heater and the second fixing heater
Data Source
AI summary
An image forming apparatus includes an AC input portion to which AC power is to be supplied from a commercial power source, an image forming unit configured to form an image on a recording material, a fixing device including a first fixing heater and a second fixing heater which are configured to generate heat, the fixing device being configured to heat the image on the recording material by using the first fixing heater and the second fixing heater to fix the image to the recording material, a first relay configured to be switched between a first state in which electric connection is established and a second state in which electric connection is not established, and a second relay configured to be switched between a third state in which electric connection is established and a fourth state in which electric connection is not established.