Transfer Roller Contact Layout for Cover-Open Power Disconnection
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Solution Overview
Problem
The high cost of interlock switches used to prevent short circuits when opening covers in image forming apparatuses is a challenge, as they are expensive and increase the overall cost of the device.
Innovation Solution
An image forming apparatus design that uses a power supply line with a first and second contact, where the second contact is separated from the first contact by a contact portion on a swingable opening and closing unit, eliminating the need for an interlock switch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an interlock switch is used to prevent short circuits when the cover is opened, then safety is improved, but cost increases
Solution Approach 1:
The patent extracts the interlock switch from the system by replacing it with a passive mechanical contact separation mechanism. The power supply line is designed to automatically disconnect from the transfer roller when the cover is opened, eliminating the need for an expensive interlock switch while maintaining safety functionality.
Solution Approach 2:
The patent uses simple, low-cost mechanical contacts instead of expensive electronic interlock switches. The contact structure is designed to be simple and inexpensive, using basic electrical contact elements that automatically separate when the cover is opened, providing safety without increasing cost.
2Reliability
If an interlock switch is used to prevent short circuits, then safety is improved, but device complexity increases
Solution Approach 1:
The patent removes the interlock switch component entirely and replaces it with a mechanical contact separation system integrated into the power supply line structure. This extraction reduces component count while maintaining the safety function through passive mechanical disconnection.
Solution Approach 2:
The patent merges the power supply function with the mechanical cover opening/closing action. The power supply line is integrated into the transfer roller assembly such that the act of opening the cover automatically separates the electrical contacts, combining safety interlocking with the existing mechanical structure.
3Ease of operation
If the power supply line remains connected when the cover is opened, then ease of operation is improved, but short circuit risk increases
Solution Approach 1:
The patent implements preliminary disconnection of the power supply line before the user can access the transfer roller area. When the cover is opened, the power supply line automatically disconnects in advance, preventing any potential short circuit before it can occur, while still allowing easy cover operation.
Solution Approach 2:
The patent uses the mechanical movement of the cover as an intermediary to control electrical connection. The cover opening/closing action serves as a mediator that automatically controls the power supply connection state, eliminating the need for separate safety switches while maintaining both safety and ease of operation.
Data Source
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AI summary
An image forming apparatus (1) includes a body housing (3), an opening and closing unit 821), an image carrier (15B), a transfer roller (152), a power supply line (23), a power supply line side contact (23C), and a transfer roller side contact (21C). The body housing (3) has an opening (3A). The opening and closing unit (21) can be opened and closed in the opening (3A) . The image carrier (15B) is provided in the body housing (3). The transfer roller (152) is provided in the opening and closing unit (21) . The power supply line (23) includes a first contact (231), and a second contact (232). The opening and closing unit (21) includes a contact portion (21T) which comes into contact with the second contact (232) and moves the second contact (232). The contact portion (21T) makes the second contact (232) come into contact with the first contact (231) when the opening and closing unit (21) is closed, and makes the second contact (232) separate from the first contact (231) when the opening and closing unit (21) is opened.