Image Forming Device Sheet Transport Timing Control
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Solution Overview
Problem
Image forming devices without transportation rollers face challenges in maintaining image alignment due to sheet size variations, leading to misalignment and potential slipping during the printing process, especially when using sheets of different lengths.
Innovation Solution
An image forming device with a controller that adjusts the timing of sheet transport and image formation based on sheet size, suspending the rotation of the feed roller at a predetermined distance from the rear end to prevent multiple sheet feeding and apply controlled transportation load, thereby ensuring proper alignment by delaying or advancing the start of image formation and transport.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the feed roller keeps rotating after the rear end of a sheet has passed to prevent multiple transportation, then sheet feeding reliability is improved, but sheet transportation timing accuracy deteriorates due to delay
Solution Approach 1:
The feed roller rotation is suspended in advance before the rear end of the sheet completely passes, at a predetermined distance L away. This preliminary suspension prevents multiple sheet feeding (improving reliability) while minimizing the delay effect on transportation timing (preserving timing accuracy).
Solution Approach 2:
The invention changes the parameter of feed roller rotation state from continuous to intermittent, suspending rotation at a specific position (distance L from rear end). This parameter change allows the system to balance between preventing multiple feeding and maintaining transportation timing accuracy.
2Ease of operation
If the feed roller rotation is suspended to prevent multiple sheet feeding, then sheet feeding control is improved, but sheet transportation speed varies causing timing mismatch
Solution Approach 1:
The feed roller rotation is suspended in advance at a predetermined position (distance L from rear end of sheet). This preliminary action provides consistent control timing regardless of sheet size variations, maintaining transportation speed consistency while preventing multiple feeding.
Solution Approach 2:
The invention dynamically adjusts the feed roller rotation state based on sheet position, suspending rotation when the sheet reaches a specific position (distance L from rear end). This dynamic control maintains consistent transportation timing while preventing multiple sheet feeding.
3Device complexity
If the image formation timing is fixed, then image formation simplicity is maintained, but image alignment accuracy deteriorates due to sheet size variations
Solution Approach 1:
The invention changes the timing parameter of image formation based on sheet size. For sheets shorter than length (M+L), the image formation start time is delayed by a predetermined time period. This parameter adjustment maintains alignment accuracy while keeping the control method relatively simple.
Solution Approach 2:
The invention applies different image formation timing strategies for different sheet sizes. Short sheets (length < M+L) receive delayed timing, while standard sheets use normal timing. This local differentiation ensures alignment accuracy for each sheet type without overly complicating the overall control system.
Data Source
AI summary
An image forming device makes a sheet pass between first rotating member and separator in a pressed position, causes second rotating member pair to transport a sheet, transports the sheet from second rotating member pair with the sheet held between third rotating member and image carrier in a transfer position, transfers an image formed on image carrier onto the sheet, and suspends rotation of first rotating member when a portion of the sheet, which is distance L away from the sheet's rear end, passes the pressed position. Provided that length 1≧(M+L) and length 2<(M+L) where M is a distance from the pressed position to the transfer position, when the sheet has length 2 in a transport direction, the device delays image formation start and/or advances sheet transport start, by a predetermined time period as compared to when the sheet has length 1 in the transport direction.