Image Forming Apparatus Delayed Power Cutoff Cover Open
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Solution Overview
Problem
Existing image forming apparatuses face issues with sudden power cutoffs when the cover is opened, leading to unstable operation, toner leakage, and potential damage to the photoconductive drum, which complicates maintenance and reduces printing quality and apparatus lifetime.
Innovation Solution
An image forming apparatus design that includes a power-supply cutoff unit to delay the cutoff time of the power-supply voltage applied to the image forming engine, allowing for a controlled shutdown without using a relay circuit, by sequentially switching off first and second switching units when the cover is opened.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the first and second switches are simultaneously switched off when the cover is opened, then the repairman or user is protected from electric shock, but the image forming engine suddenly stops operation causing unstable power-off, toner leakage, and potential damage to the photoconductive drum
Solution Approach 1:
The control unit receives a cover open signal and initiates a preliminary shutdown sequence before complete power cutoff. The controller commands the image forming engine to stop operation in a controlled manner, allowing the developing roller to stop rotating and preventing toner leakage before the power supply is fully disconnected. This preliminary action ensures safe and stable power-off while maintaining electric shock protection.
2Reliability
If a relay circuit is used as a delay circuit to allow continuous power-supply voltage during a predetermined period, then the image forming engine can normally stop operation, but the production cost increases and circuit complexity increases
Solution Approach 1:
The patent replaces the mechanical relay circuit with an electronic control system. The control unit, powered by the 5V power supply, receives the cover open signal and electronically controls the shutdown timing of the 24V power supply to the image forming engine. This electronic approach achieves the same delayed power cutoff function as a relay circuit but with simpler circuitry and lower production cost.
Solution Approach 2:
The control unit serves multiple functions: it monitors the cover open signal, controls the shutdown timing of the power supply, and manages the overall power management of the image forming apparatus. By making the control unit multi-functional, the patent eliminates the need for separate relay circuits while maintaining the controlled shutdown capability.
Data Source
AI summary
An image forming apparatus including: a main body; a cover rotatably connected to the main body; a power-supply unit to generate a first power-supply voltage and a second power-supply voltage; an image forming engine to receive the first power-supply voltage from the power-supply unit; a control unit to receive the second power-supply voltage from the power-supply unit, and to stop an operation of the image forming engine, when the second power-supply voltage is cutoff. The image forming apparatus further includes a power-supply cutoff unit that delays a cutoff time of the first power-supply voltage, as compared to a cutoff time of the second power-supply voltage, according to an opening of the cover. The cutoff unit includes a first switch to cutoff first power-supply voltage to the image forming engine, and a second switch to cutoff the second power-supply voltage to control unit.