Image Forming Apparatus Power State Transition Logic
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Solution Overview
Problem
Image forming apparatuses face challenges in transitioning to and returning from hibernation state due to the erasure of sub CPU execution programs stored in outside-OS-management areas when the main memory is powered off, leading to issues in loading programs during suspend and hybrid sleep modes.
Innovation Solution
The image forming apparatus includes a first controller that manages the transition to and from power saving states, including suspend and hibernation, by controlling the timing of loading programs for the sub CPU, ensuring program integrity across different power states by distinguishing between suspend and hibernation states and using non-volatile storage for data management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the image forming apparatus transitions to hibernation state where current is not applied to memory, then power consumption is reduced, but the sub CPU execution programs stored in outside-OS-management areas are erased
Solution Approach 1:
The system performs preliminary actions by saving sub CPU execution programs to non-volatile storage before transitioning to hibernation state, and restores them after hibernation. This preliminary preparation ensures that critical information is preserved despite memory power-off during hibernation, resolving the contradiction between power saving and information retention.
2Loss of information
If the image forming apparatus uses suspend state where current is applied to memory, then sub CPU execution programs are maintained, but power consumption is higher compared to hibernation
Solution Approach 1:
The system dynamically selects between suspend and hibernation states based on operational requirements. When sub CPU execution is anticipated soon, suspend state maintains programs in memory with acceptable power consumption. When power saving is prioritized and sub CPU execution can be delayed, hibernation state is used with program restoration from non-volatile storage. This dynamic adaptation resolves the contradiction between information retention and power consumption.
3Speed
If the system loads sub CPU programs into memory before suspend transition, then fast start is achieved, but the timing differs from hibernation state causing operational issues
Solution Approach 1:
The system applies different local quality treatments for suspend and hibernation states. In suspend state, sub CPU programs are loaded into memory before transition to enable fast start. In hibernation state, programs are saved to non-volatile storage and restored after wake-up. This localized differentiation of program handling strategies according to the specific power state resolves the timing synchronization issues while maintaining fast start capability where applicable.
Data Source
AI summary
An image forming apparatus is controlled as follows. In a case where a first controller receives an end process event, the first controller that causes the image forming apparatus to transition to a power saving state causes the image forming apparatus to transition to a hibernation state in a case where transition to the hibernation state is enabled, and loads a program for a second controller into the memory and causes the image forming apparatus to transition to a suspend state in a case where transition to the suspend state is enabled.