Image Forming Apparatus Power Management via WDT Flag Notification
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Solution Overview
Problem
In high-functional image forming apparatuses, when a malfunction occurs, the system instability prevents proper handling of watchdog timer (WDT) interrupts, leading to potential damage from incorrect power plane reinitialization and difficulty in monitoring devices whose power is not controlled by the malfunctioning device.
Innovation Solution
Implementing a control unit with non-volatile storage to enable a flag for WDT notification, allowing the second control unit to notify devices whose power is not controlled by the malfunctioning device, ensuring proper initialization and preventing damage from reverse currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the controller centrally controls the entire power supply to manage high-functional devices, then the power management efficiency is improved, but the complexity of monitoring all devices increases
Solution Approach 1:
The patent divides the monitoring responsibility into segments: the controller monitors devices whose power it controls, while each device monitors itself. This segmentation reduces the controller's monitoring burden while maintaining centralized power management efficiency.
Solution Approach 2:
Each device is designed to monitor its own operational state and trigger WDT interrupts independently, eliminating the need for the controller to continuously monitor all devices. This self-service approach maintains power management efficiency while reducing monitoring complexity.
2Object-affected harmful factors
If the WDT interrupt resets only the device whose power is controlled by the malfunctioning device, then the risk of reverse current damage is reduced, but the system reinitialization becomes incomplete
Solution Approach 1:
The patent implements a feedback mechanism where devices send notifications to the controller about WDT interrupt occurrences. This feedback allows the controller to coordinate comprehensive system reinitialization while maintaining safe power sequencing that prevents reverse current damage.
Solution Approach 2:
The controller receives advance notification of WDT interrupts and prepares the appropriate reinitialization sequence before power is restored. This preliminary action ensures complete system reinitialization while maintaining safe power sequencing to prevent damage.
3Reliability
If the controller monitors the state of all devices including those whose power is not controlled by the malfunctioning device, then the system reliability is improved, but the controller's processing burden increases
Solution Approach 1:
The monitoring function is segmented between the controller and individual devices. The controller monitors devices under its power control, while each device monitors its own state. This division reduces the controller's processing burden while maintaining system reliability.
Solution Approach 2:
Devices act as intermediaries by monitoring their own states and notifying the controller of WDT interrupts. This intermediary approach allows the controller to receive critical information without continuously monitoring all devices, reducing processing burden while maintaining reliability.
Data Source
AI summary
A device of a lower hierarchy in a power supply configuration sets a flag of a non-volatile storage area when the device of the lower hierarchy reset by WDT. In a case where the flag at the time of starting, the device of an upper hierarchy is notified that the device of the lower hierarchy in the power supply configuration is reset. Thus, the device of the upper hierarchy initializes the entire system, and the image forming apparatus can be operated.