Sheet Feeding Device Speed Compensation for Print Positioning
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Solution Overview
Problem
Conventional sheet feeding devices without sheet registration processes face challenges in accurately positioning printing sheets due to variations in rotation speeds of pick-up and feed rollers, leading to inconsistent nipping timing and potential misalignment at the print start position.
Innovation Solution
A sheet feeding device with a sheet detection unit, speed detection unit, and compensation mechanism that adjusts the rotation speeds of the rollers to ensure the sheet is accurately positioned at the target print start position by compensating for differences in rotation speeds and ratios, using a control unit to calculate and apply the necessary rotation amounts based on detected speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the pick-up roller and feed rollers are driven by different motors without speed synchronization, then the sheet feeding process is simple and fast, but the nipping timing becomes inconsistent leading to positioning errors at the print start position
Solution Approach 1:
The system performs preliminary speed detection of the pick-up roller and feed rollers before the sheet feeding operation. Based on the detected speeds, the control unit pre-calculates and sets the rotation amount of the feed rollers to compensate for speed variations. This preliminary action ensures that even with different motor speeds, the sheet will be accurately positioned at the print start position without requiring complex real-time synchronization mechanisms.
Solution Approach 2:
The invention incorporates speed detection units that continuously monitor the rotation speeds of the pick-up roller and feed rollers. The detected speed information is fed back to the control unit, which adjusts the rotation amount of the feed rollers accordingly. This feedback mechanism enables dynamic compensation for speed variations, maintaining positioning accuracy without requiring the motors to be perfectly synchronized.
2Manufacturing precision
If the feed rollers are controlled to stop after rotating by a predetermined amount, then the control process is simple, but positioning accuracy deteriorates due to variations in nipping timing caused by rotation speed errors
Solution Approach 1:
The invention dynamically changes the rotation amount parameter of the feed rollers based on detected rotation speeds. Instead of using a fixed predetermined rotation amount, the control unit calculates the rotation amount by compensating for speed variations of both the pick-up roller and feed rollers. This parameter change approach maintains simple stop control while achieving high positioning accuracy through adaptive rotation amount adjustment.
3Reliability
If speed detection and compensation mechanisms are added to synchronize roller speeds, then positioning accuracy improves, but the device complexity and cost increase
Solution Approach 1:
The invention replaces complex mechanical speed synchronization mechanisms with electronic speed detection and control. Instead of using mechanical linkages or gear systems to synchronize the pick-up roller and feed rollers, the system uses independent motors with electronic speed detection units and a control unit that calculates and adjusts rotation amounts. This substitution maintains reliability while avoiding complex mechanical structures.
Data Source
AI summary
A sheet feeding device includes a first roller configured to feed a sheet in a first direction along a first feed path, a second roller arranged on a downstream side of the first roller and configured to feed the sheet in the first direction along the first feed path, a sheet detection unit arranged between the first roller and the second roller. A rotation amount of the second roller from detection of the leading end of the sheet by the sheet detection unit to arrival of the sheet at a predetermined position on the downstream side is compensated based on the rotation speed of the first roller within a first period, which is a period from start of feeding of the sheet as the first roller is started to be driven to the detection of the leading end of the sheet by the sheet detection unit.