Sheet Reversing Unit Nip Switching Mechanism
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Solution Overview
Problem
Conventional sheet conveying apparatuses for two-sided printing require a switchback unit and a separate discharge unit, increasing the size and complexity of the image forming apparatus due to the need for sheet reversal after complete discharge from the reversing roller group.
Innovation Solution
A sheet conveying apparatus that switches the nip portion before the trailing edge of the sheet has completely discharged from the first nip portion, using a drive roller, discharge roller, and reversing roller configuration to change the sheet conveyance direction without the need for a separate discharge unit, allowing continuous operation and reduced apparatus size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a switchback unit and separate discharge unit are provided for sheet reversal after complete discharge, then sheet reversing function is achieved, but apparatus size and complexity increase
Solution Approach 1:
The patent merges the discharge unit and reversing unit into a single integrated reversing unit. The drive roller and discharge roller form a first nip portion for discharging sheets, while the drive roller and reversing roller form a second nip portion for reversing sheets. This consolidation eliminates the need for separate switchback and discharge units, reducing apparatus size and complexity while maintaining the sheet reversing function
Solution Approach 2:
The drive roller serves multiple functions: it acts as a discharge roller forming the first nip portion with the discharge roller for sheet discharge, and simultaneously acts as a drive roller forming the second nip portion with the reversing roller for sheet reversal. This multi-functionality reduces the number of components needed and simplifies the overall apparatus structure
2Ease of operation
If sheet reversing is performed after complete discharge from the first nip portion, then sheet conveyance control is simplified, but productivity decreases due to waiting time
Solution Approach 1:
The patent implements preliminary action by switching the nip portion from the first nip portion to the second nip portion before the trailing edge of the sheet completely discharges from the first nip portion. This allows the next sheet to be conveyed to the first nip portion while the current sheet is being reversed, eliminating waiting time and enabling continuous operation that improves productivity
Solution Approach 2:
The patent ensures continuity of useful action by overlapping the discharge of one sheet with the reversal of another sheet. While the first sheet is being reversed in the second nip portion, the second sheet is simultaneously conveyed through the first nip portion. This continuous operation eliminates idle time and maximizes productivity in two-sided printing
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables efficient two-sided printing with reduced apparatus size and complexity by switching the sheet conveyance direction within the reversing unit, improving productivity and resource utilization.
Implementation Method 1
a first nip portion at which the drive roller and the discharge roller contact each other via the sheet S
Implementation Method 2
a second nip portion at which the drive roller and the reversing roller contact each other via the sheet S
Data Source
Figure 1
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AI summary
A reversing unit has a drive roller (62), a discharge roller (61) for forming a first nip portion (N1) together with the drive roller, and a conveyance roller (63) for forming a second nip portion (N2) together with the drive roller. The reversing unit moves any one of the rollers and nips a sheet at a plurality of nip portions when moving the roller to switch the nip portion for nipping a sheet from a first nip portion to a second nip portion and change the sheet conveyance direction from a first direction to a second direction.