Separator Spacer Gap Control Fixing Device
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Solution Overview
Problem
The existing separators for fixing devices in electrophotographic image forming apparatuses face accuracy issues in maintaining a consistent gap between the separator and the rotary members, due to shape and installation tolerance, which affects the separation of recording media from the rotary fixing member or pressure member.
Innovation Solution
A separator configuration with a separation plate and plate-shaped spacers is employed, where the spacers are disposed between the edge portion of the separation plate and the rotary member's surface, forming a gap determined by the spacers' thickness, thus isolating the gap from shape and installation tolerance variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If positioning members are provided at positions separated from the edge portion of the separation plate, then the separator structure is simpler and easier to manufacture, but the gap formation accuracy between the separator and rotary member deteriorates due to shape and installation tolerances
Solution Approach 1:
A positioning member is introduced as an intermediary element between the separation plate and the rotary member. This positioning member has a contact portion that directly contacts the rotary member and a non-contact portion that faces the separation plate, creating a mediated positioning system that eliminates direct dependency on the separation plate's edge portion positioning accuracy.
Solution Approach 2:
The design changes the positioning parameter from the edge portion position of the separation plate to the thickness dimension of the positioning member. By making the gap distance equal to the thickness of the positioning member, the positioning accuracy depends on the easily controllable thickness parameter rather than the difficult-to-control edge position parameter.
2Manufacturing precision
If the gap between the separator and rotary member is made narrow to improve separation accuracy, then the separation precision improves, but the risk of contact and stress generation increases
Solution Approach 1:
The positioning member serves as a mediator that maintains a precise gap between the separation plate and rotary member. By positioning the non-contact portion of the positioning member to face the separation plate with a predetermined distance, it ensures consistent spacing that prevents both excessive gap and harmful contact.
Solution Approach 2:
The positioning member is designed beforehand to provide a safety buffer against contact between the separation plate and rotary member. The predetermined distance between the non-contact portion of the positioning member and the separation plate edge portion creates a cushioning gap that prevents harmful contact while maintaining accurate positioning.
Data Source
AI summary
A separator is provided for a fixing device including a rotary fixing member that fixes a toner image on a recording medium and a rotary pressure member pressed against the rotary fixing member to form a fixing nip portion for nipping the recording medium. The separator includes a separation plate and plate-shaped spacers. The separation plate is disposed downstream of the fixing nip portion in a medium feeding direction, with an edge portion of the separation plate facing an outer circumferential surface of the rotary fixing member or the rotary pressure member. The spacers are disposed between portions of the edge portion of the separation plate and the outer circumferential surface of the rotary fixing member or the rotary pressure member to surround the portions of the edge portion in a direction intersecting with an extending direction of the edge portion.