Power Supply Control Unit for Image Forming Apparatus Shutdown
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Solution Overview
Problem
Conventional image forming apparatuses lack an effective mechanism to differentiate between normal and abnormal states during power shutdown operations, potentially leading to data corruption or unintended restarts when a long press of the power switch occurs, especially when the main control unit is in a normal state.
Innovation Solution
The image forming apparatus includes a power supply control unit that detects the pressing time of the power switch and initiates a power shutdown process only if the predetermined time is reached without a change in the control signal, thereby distinguishing between normal and abnormal states of the main control unit, ensuring controlled shutdowns and preventing data corruption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the main control unit counts pressing time and enters shutdown mode after a predetermined time, then the shutdown function is achieved, but data corruption or unintended restarts may occur when the main control unit is in a normal state
Solution Approach 1:
The patent introduces a power supply control unit as an intermediary between the power switch and the main control unit. This intermediary monitors the control signal state independently and can detect abnormal states (where the main control unit fails to respond) without being affected by the main control unit's operational status. The power supply control unit then directly controls the power supply circuit to execute forced shutdown, preventing data corruption while maintaining reliable shutdown functionality.
Solution Approach 2:
The patent segments the control system into two independent parts: the main control unit for normal operation and the power supply control unit for power management and abnormal state detection. This segmentation allows the power supply control unit to independently monitor the control signal and detect abnormal states without being influenced by the main control unit's processing status, thereby preventing unintended restarts and data corruption during shutdown operations.
2Reliability
If the power supply control unit forcibly starts power shutdown when pressing time reaches predetermined time without control signal change, then abnormal states are handled, but normal shutdown operations may be interfered with
Solution Approach 1:
The power supply control unit continuously monitors the control signal from the power switch and compares it against expected states. When the control signal remains unchanged for the predetermined time period, this feedback indicates an abnormal state (such as the main control unit being unresponsive). The system then triggers forced shutdown only in this specific abnormal condition, while normal shutdown operations (where the control signal changes appropriately) are not interfered with.
3Ease of operation
If the main control unit performs shutdown control process, then normal shutdown is achieved, but the system cannot differentiate between normal and abnormal states during long press operations
Solution Approach 1:
The power supply control unit acts as an intermediary that independently monitors the control signal state without relying on the main control unit's processing. By directly detecting whether the control signal changes during the pressing period, the system can precisely differentiate between normal shutdown operations (signal changes) and abnormal states (no signal change), enabling appropriate response actions.
Data Source
AI summary
An image forming apparatus includes a power switch, a power supply circuit, a power supply control unit, and a main control unit that sends a control signal to the power supply control unit and allows the power supply control unit to perform the power supply process based on the control signal. The power supply control unit starts to count pressing time as an elapsed time while the power switch is kept pressed. If the pressing time reaches a predetermined time without a change in the control signal, the power supply control unit forcibly starts a power shutdown process. If the control signal changes before the pressing time reaches the predetermined time, the power supply control unit starts the power shutdown process after receiving from the main control unit the control signal requesting for the power shutdown process.