Fixing Nip Pressure Release for Safe Paper Jam Removal
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Solution Overview
Problem
In image forming apparatuses, when the door is opened during operation, the interruption of power supply to the driving circuit causes recording material jams, making it difficult to remove stuck paper from the nip portion, potentially damaging the apparatus and the paper.
Innovation Solution
An image forming apparatus with a door opening/closing detection unit, a decision unit to check for paper at the nip portion, and a control unit that releases pressure at the nip portion when the door is opened and paper is detected, allowing safe removal of jammed paper.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If power supply to driving circuit is interrupted when door is opened, then user safety is improved (prevention of electrocution), but recording material gets jammed in conveyance path and cannot be removed
Solution Approach 1:
The control unit performs preliminary action by releasing the pressurized state of the nip portion before the user needs to remove jammed paper. When door opening is detected and jammed paper is confirmed, the control unit automatically releases pressure at the nip portion, creating favorable conditions for paper removal before the user attempts to access the conveyance path.
Solution Approach 2:
The control unit acts as an intermediary between the door opening detection and the paper removal process. It receives the door opening signal, determines the presence of jammed paper, and autonomously releases pressure at the nip portion, mediating between safety requirements and operational needs without requiring user intervention in the pressure control mechanism.
2Reliability
If pressure is maintained at nip portion during door opening, then fixing unit continues to hold recording material, but apparatus or recording material may be damaged when user removes jammed paper
Solution Approach 1:
The invention converts the potentially harmful situation of maintained pressure during door opening into a beneficial outcome. By detecting door opening and automatically releasing pressure at the nip portion, the system transforms what would be a damaging condition (pressure on jammed paper during user access) into a protective action that prevents damage to both the apparatus and recording material while enabling safe paper removal.
3Object-affected harmful factors
If power supply is interrupted by interlock circuit, then driving circuit stops operation, but pressure releasing operation cannot be performed to remove JAM paper
Solution Approach 1:
The system performs self-service by autonomously releasing pressure at the nip portion when door opening is detected and jammed paper is present. The control unit automatically executes the pressure release operation without requiring user activation, enabling the fixing unit to assist in paper removal even though the interlock circuit has interrupted power supply to most driving circuits.
Data Source
AI summary
An image forming apparatus comprising a conveyance path of recording material comprises a door, when opened, the inside of the apparatus is exposed, and an interlock circuit which detects opening/closing state of the door. The detection unit of the door is arranged on the conveyance path. At the arranged position, the image forming apparatus comprises a registration sensor for detecting presence and absence of the recording material and delivery sensor. The CPU controls pressure to the recording material S passing the fixing nip portion formed by a pair of rollers arranged on the conveyance path. Also, the CPU decides whether the recording material exists at the fixing nip portion based on the respective detection result from the registration sensor and the delivery sensor.