Document Conveying Device Sheet Feeding Speed Control
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Solution Overview
Problem
Existing document conveying devices face challenges in maintaining high productivity by ensuring documents reach the reading position without delay, regardless of conveying speed, due to limitations in controlling sheet-to-sheet intervals and motor rotation speeds.
Innovation Solution
A document conveying device with a document tray, sheet feeding rotary member, and secondary sheet feeding roller, controlled by a controller that adjusts feeding speeds and stops to optimize document delivery, allowing for primary and secondary sheet feeding at different speeds to ensure timely arrival at the reading position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the conveying speed is increased to reduce sheet-to-sheet intervals, then the productivity is improved, but the motor rotation speed may already be close to maximum speed and cannot be increased further to cancel delays
Solution Approach 1:
The controller performs preliminary action by momentarily stopping the sheet feeding rotary member before the trailing end of the document sheet leaves it. This advance stopping prevents excessive sheet-to-sheet intervals from occurring in the first place, ensuring that subsequent sheets are fed at optimal intervals without needing to maximize conveying speed continuously.
Solution Approach 2:
The system implements periodic action by alternating between rotation and momentary stopping of the sheet feeding rotary member. This periodic on-off control creates consistent sheet intervals without requiring continuous high-speed operation, allowing the motor to operate within its speed capabilities while maintaining high productivity.
2Productivity
If the sheet feeding speed is increased to deliver documents without delay, then the productivity is improved, but the complexity of control increases due to varying conveying speeds in different modes
Solution Approach 1:
The controller changes operational parameters by switching between primary sheet feeding speed and secondary sheet feeding speed based on the reading mode. This parameter adjustment allows the system to optimize document delivery timing for each specific mode without requiring complex real-time calculations, simplifying the overall control architecture.
Solution Approach 2:
The system implements dynamics by making the sheet feeding speed adjustable between different modes. The controller dynamically switches between primary and secondary feeding speeds according to the specific reading mode requirements, allowing flexible adaptation without permanent complex control mechanisms for each mode.
3Productivity
If the motor rotation speed is maximized to cancel sheet delays, then the productivity is improved, but the difficulty of control increases due to case-by-case speed variation requirements
Solution Approach 1:
The controller performs self-service by automatically determining when to momentarily stop the sheet feeding rotary member based on the position of the trailing end of the document sheet. This self-regulating mechanism eliminates the need for external intervention or complex case-by-case control decisions, making operation simple while maintaining high productivity.
Solution Approach 2:
The system uses feedback by monitoring the position of the trailing end of the document sheet relative to the sheet feeding rotary member. This feedback information triggers the momentary stopping action automatically, creating a closed-loop control system that is easy to operate but effectively maintains optimal sheet intervals.
Data Source
AI summary
A controller starts sheet feeding at a primary sheet feeding speed, then momentarily stops a sheet feeding rotary member, and thereafter starts secondary sheet feeding. When the secondary sheet feeding speed equals a first speed, the controller momentarily stops the sheet feeding rotary member such that the leading end of a document sheet stops at a first stop position. When the secondary sheet feeding speed equals a second speed, the controller momentarily stops the sheet feeding rotary member such that the leading end of a document sheet stops at a second stop position. The second stop position is located downstream of the first stop position in the document conveying direction.