Sheet Conveyance Path Merging for Double-Sided Printing
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Solution Overview
Problem
Existing image forming apparatuses face challenges in efficiently managing the conveyance path length and sheet spacing during double-sided printing, leading to potential collisions and increased apparatus size due to separate sheet discharging and reversal paths.
Innovation Solution
The apparatus overlaps the sheet discharging and reversal paths, utilizing a controller to manage a branching and merging conveyance path system with distinct conveyance directions, allowing for consecutive image forming and sheet interval adjustment processes to prevent collisions by setting a time difference between sheets based on calculated time periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sheet discharging path and reversal path are arranged as independent separate paths, then the sheet can be discharged and reversed without interference, but the whole length of the conveyance path becomes long and the apparatus size increases
Solution Approach 1:
The patent merges the sheet discharging path and reversal path into a single shared conveyance path. The discharge and reverse roller serves both functions, and the circulation roller manages sheet flow for both discharge and reversal operations. This consolidation eliminates redundant path sections and reduces the overall conveyance path length while maintaining reliable sheet handling through controlled sheet interval adjustment.
2Reliability
If the conveyance path length increases, then sheet discharge and reversal can be performed separately, but the numbers of rollers and drive sources increase and the apparatus size becomes large
Solution Approach 1:
The discharge and reverse roller is designed to perform multiple functions: it can discharge sheets to the discharge tray or reverse sheets back into the conveyance path for double-sided printing. The circulation roller similarly handles both discharged sheets and sheets being reversed. This multi-functionality reduces the total number of rollers and drive sources needed compared to having completely separate paths for discharge and reversal.
3Reliability
If consecutive double-sided printing is performed by controlling sheet space between sheets, then collision between sheets can be suppressed, but the conveyance speed control at each point becomes complex
Solution Approach 1:
The controller monitors sheet positions and conveyance speeds throughout the path, using feedback from sheet detection to adjust conveyance speeds dynamically. This ensures that sheets are spaced appropriately to prevent collisions during reversal operations, while the controller coordinates the discharge and reverse roller and circulation roller to maintain proper timing and spacing automatically.
Data Source
AI summary
A controller calculates a first time period T1 and a second time period T2. The first time period T1 is defined as a time period required for conveying the end portion of the sheet, which is conveyed in a first conveyance direction E, disposed on the upstream side in the first conveyance direction E up to a reversal position A3. The second time period T2 is defined as a time period required for conveying an end portion of the reversed sheet disposed on an upstream side in a second conveyance direction R from the reversal position A3 to a branching point A1.