Sheet Conveyance Path Switching for Double-Sided Printing Safety
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Solution Overview
Problem
In image forming apparatuses, there is a risk of user contact with protruding sheets during double-sided printing, and potential collisions between sheets on the discharge tray, due to conveyance delays or misalignment, which can hinder printing speed and safety.
Innovation Solution
The apparatus includes a conveyance path system with a discharge path and a reconveyance path, where the controller switches the conveyance of sheets between these paths based on predetermined conditions, ensuring that sheets are either reconveyed to the image forming unit or discharged efficiently, preventing user contact and collisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the sheet is switchbacked by using the discharge path after printing is terminated on the back surface of the second sheet, then the printing speed is improved, but the sheet protrudes on the discharge tray causing user contact risk and potential sheet collision
Solution Approach 1:
The patent divides the sheet conveyance system into three distinct paths: the discharge path for normal sheet discharge, the reconveyance path for returning sheets to the image forming unit, and a temporary holding position. This segmentation allows the controller to direct sheets to different paths based on their conveyance state, preventing protruding sheets from causing harm while maintaining high-speed printing operation.
Solution Approach 2:
The reconveyance path acts as an intermediary between the discharge path and the image forming unit. When a sheet is switchbacked, instead of directly discharging it to the discharge tray where it would protrude and cause harm, the sheet is conveyed through the reconveyance path to a temporary holding position, then returned to the image forming unit. This intermediary path eliminates the harmful protrusion effect while preserving the high-speed conveyance benefit.
2Object-affected harmful factors
If the sheet is switchbacked by using the reconveyance path, then user contact and sheet collision are prevented, but the printing speed is reduced due to conveyance delay
Solution Approach 1:
The patent implements a dynamic conveyance control system where the controller continuously monitors the conveyance state of sheets and dynamically switches between different paths (discharge path vs. reconveyance path) based on real-time conditions. This dynamic adjustment allows the system to optimize between safety (preventing protrusion) and speed (maintaining high-speed printing) depending on the specific conveyance circumstances.
Solution Approach 2:
The controller changes the conveyance parameters by selecting different paths based on sheet position and conveyance timing. When the sheet conveyance timing indicates potential protrusion risk, the system changes the path selection to the reconveyance path. When timing allows safe discharge, the system changes to the discharge path. This parameter change approach enables optimization of both safety and speed based on real-time conveyance conditions.
3Productivity
If the conveyance space between sheets is shortened to improve printing speed, then productivity increases, but the risk of sheet misalignment and protrusion increases
Solution Approach 1:
The controller monitors the conveyance state of sheets and uses this feedback information to determine the appropriate path (discharge or reconveyance). By continuously tracking sheet position and timing, the system can detect when shortened conveyance space might cause misalignment or protrusion, and adjust the conveyance path accordingly to maintain reliability while preserving high-speed printing performance.
Data Source
AI summary
An image forming apparatus includes: a main apparatus body having an image forming unit and a discharge tray; and a controller. The main apparatus body includes a conveyance path along which a sheet passed through the image forming unit is conveyed; a discharge path branched from the conveyance path and connected to the discharge tray; and a reconveyance path having a first path different from the discharge path and a second path for conveying the sheet to the image forming unit. In a double-sided printing, if a first sheet has passed through the first path when a forward end of a second sheet arrives at a predetermined position in the conveyance path, the controller conveys the second sheet to the first path and then conveys the second sheet to the second path.