Entrance Guide Locking Member for Jammed Sheet Recovery
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In image forming apparatuses, jammed sheets often get stuck between the fixing roller and pressure roller, making it difficult to recover the sheet due to the stiffness difference between the jammed sheet and auxiliary guide members, especially when the auxiliary guide member is weaker, causing the sheet to enter the lower side of the entrance guide during reverse rotation.
Innovation Solution
The apparatus includes a manual discharge member and a locking member with a bending portion on the entrance guide to guide the sheet back to the guide member, allowing the central portion of the sheet to be bent along the guide surface, facilitating easy recovery of the jammed sheet by preventing it from entering the lower side of the entrance guide.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a plate-shaped auxiliary guide member is disposed on the tip end of the entrance guide to prevent the jammed sheet from entering between the entrance guide and pressure roller, then the sheet guidance is improved, but when the auxiliary guide member has weaker stiffness than the jammed sheet, the sheet enters the lower side of the entrance guide during reverse rotation, making it difficult to recover the jammed sheet
Solution Approach 1:
The auxiliary guide member is divided into a plate-shaped portion for guiding the sheet and a locking member with a bending portion for securing the sheet during recovery. This segmentation allows each part to have optimized properties: the plate-shaped portion provides guidance while the locking member provides the necessary stiffness and locking function without requiring the entire auxiliary guide member to be highly rigid.
Solution Approach 2:
The locking member is positioned on the back side of the guide face to preliminarily lock the downstream-side end of the sheet before the reverse rotation occurs. This preliminary locking action prevents the sheet from entering the lower side of the entrance guide during recovery, solving the problem of sheet misplacement while maintaining ease of operation.
2Ease of operation
If the auxiliary guide member is made with sufficient stiffness to prevent sheet entry during reverse rotation, then the ease of jam recovery is improved, but the device complexity increases due to the need for stronger, more robust components
Solution Approach 1:
Instead of making the entire auxiliary guide member highly rigid, the locking member is designed with a specific bending portion that provides localized stiffness only where needed for locking. The rest of the auxiliary guide member can remain relatively simple in structure, reducing overall device complexity while maintaining ease of jam recovery.
Solution Approach 2:
The locking member incorporates a bending portion with a curved surface that contacts the sheet. This curved surface provides effective locking through geometric constraint rather than relying solely on high stiffness, simplifying the structural requirements of the auxiliary guide member while maintaining ease of operation.
Data Source
AI summary
An image forming apparatus is designed to easily recover a jammed sheet nipped by a fixing roller and a pressure roller. In an entrance guide which guides a sheet to a fixing nip portion between the fixing roller and the pressure roller, a bending portion is provided on a back side of a guide face which guides the sheet to the fixing nip portion. Then, when the sheet to be discharged toward the entrance guide by a manual discharge member enters the back side of the entrance guide, a downstream end of the sheet, in a discharging direction of the sheet, is locked to the bending portion, and thus the central portion of the sheet in the sheet discharging direction is bent along the surface of the guide face by discharging the sheet in a state where the downstream end in the discharging direction is locked.