Sheet Conveyance Device Nip Switching Mechanism
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Solution Overview
Problem
Existing sheet conveyance devices in image forming apparatuses require a switchback portion for sheet reversal, leading to increased apparatus size due to the need for a separate sheet discharge portion, which complicates the layout and reduces efficiency in two-sided printing operations.
Innovation Solution
A sheet conveyance device with a switching unit that changes the nip portions before the sheet is completely discharged from the first nip portion, allowing the sheet to be switched to a second nip portion without the need for a separate discharge portion, utilizing a first rotating member, a second rotating member, and a third rotating member to convey the sheet in different directions and switch the nip state using a cam-driven mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a switchback portion is provided for sheet reversal, then sheet conveyance function is achieved, but apparatus size increases
Solution Approach 1:
The patent merges the sheet discharge portion with the reversing portion into a single integrated unit. The sheet discharge roller is positioned to form a nip portion with the driving roller, and this same nip portion is used for reversing sheets. By combining these functions, the apparatus eliminates the need for a separate switchback portion, thereby reducing apparatus size while maintaining both sheet discharge and reversal capabilities.
Solution Approach 2:
The first nip portion formed by the driving roller and sheet discharge roller serves multiple functions: it acts as both the sheet discharge path and the reversing mechanism. The sheet discharge roller not only discharges sheets but also works in conjunction with the driving roller to create the nip portion that reverses sheets by rotating in opposite directions. This multi-functional design eliminates redundant components and reduces overall apparatus size.
2Ease of operation
If a separate sheet discharge portion is provided, then sheet discharge function is achieved, but device complexity increases
Solution Approach 1:
The patent combines the sheet discharge portion and reversing portion into one integrated structure. The sheet discharge roller is positioned to form a nip portion with the driving roller, and this same nip portion performs both discharge and reversal functions. By merging these components, the apparatus reduces structural complexity while maintaining distinct discharge and reversal capabilities through coordinated roller rotation.
Solution Approach 2:
The first nip portion serves dual purposes: it is both the sheet discharge path and the reversing mechanism. The sheet discharge roller not only discharges sheets but also works with the driving roller to create the nip portion that reverses sheets. This multi-functional design eliminates redundant components and simplifies the overall apparatus structure.
3Ease of operation
If sheet is completely discharged to switchback portion, then reversal is achieved, but productivity decreases
Solution Approach 1:
The patent implements preliminary switching of the nip portion before the sheet is completely discharged from the first nip portion. The switching unit detects the sheet position and switches from the first nip portion to the second nip portion in advance, allowing the sheet to be conveyed to the reversing portion while the first nip portion is already prepared for the next sheet. This overlapping operation eliminates idle time and improves continuous printing productivity.
Solution Approach 2:
The patent enables continuous operation by allowing the first nip portion to immediately begin conveying the next sheet after switching to the second nip portion for the current sheet's reversal. This continuous overlapping operation ensures that both nip portions are constantly utilized without idle time, maximizing productivity during two-sided printing operations.
Data Source
AI summary
A sheet conveyance device includes first, second, and third rotating members and a switching unit. The first rotating member rotates in one direction. The second rotating member conveys a sheet in a first direction with the first rotating member rotating. The third rotating member conveys the sheet in a second direction, different from the first direction, in conjunction with the first rotating member rotating. The switching unit switches from a first state where the second rotating member contacts a sheet first surface and the first rotating member contacts a sheet second surface to a second state in which the first rotating member contacts the first surface of the sheet and the third rotating member contacts the sheet second surface by moving the second rotating member before a trailing edge of the sheet conveyed in the first direction is conveyed by the first rotating member and the second rotating member.