Imaging Roller Speed Control for Sheet Conveyance Reliability
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Solution Overview
Problem
In image forming apparatuses, when the discharge roller pair and the conveyance roller pair are driven by the same motor to reduce costs, controlling the motor to accelerate the discharge roller pair can inadvertently accelerate the conveyance roller pair, leading to issues where the accelerated conveyance roller pair fails to receive subsequent sheets fed at a lower speed from the image forming unit.
Innovation Solution
Implementing a control unit that switches the speed of the conveyance roller pair and the discharge roller pair between two speeds, with the motor controlled to accelerate the discharge roller pair to a higher speed only when the trailing end of the sheet reaches a specific position, and decelerate when the leading end of the subsequent sheet reaches another position upstream, ensuring proper sheet alignment and detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the discharge roller pair and conveyance roller pair are driven by the same motor to reduce cost, then device complexity is reduced, but the conveyance roller pair cannot receive subsequent sheets when the motor accelerates the discharge roller pair
Solution Approach 1:
The patent applies dynamics by making the roller speeds adjustable and independent through separate drive mechanisms. The discharge roller pair and conveyance roller pair can operate at different speeds simultaneously, allowing the system to adapt to different operational phases (acceleration, constant speed, deceleration) without compromising sheet conveyance reliability
Solution Approach 2:
The patent segments the drive system into separate motors for the discharge roller pair and conveyance roller pair. This segmentation allows independent control of each roller pair's speed, enabling the discharge roller pair to accelerate for high-speed discharge while the conveyance roller pair maintains appropriate speed to receive subsequent sheets from the image forming unit
2Productivity
If the discharge roller pair accelerates the sheet to shorten printing time, then productivity is improved, but the accelerated conveyance roller pair fails to receive subsequent sheets fed at lower speed
Solution Approach 1:
The system dynamically adjusts the speed of each roller pair based on operational requirements. The discharge roller pair can accelerate to high speeds to shorten printing time, while the conveyance roller pair independently maintains a speed appropriate for receiving sheets from the image forming unit, ensuring both productivity and reliable sheet reception
Solution Approach 2:
The patent changes the speed parameters of different roller pairs independently. By allowing the discharge roller pair to operate at high speeds during discharge while the conveyance roller pair operates at lower speeds for sheet reception, the system achieves both high productivity and reliable sheet handling
Data Source
AI summary
An image forming apparatus includes an image forming unit to form an image on a sheet while conveying the sheet at an image forming speed, a discharge roller pair to discharge the sheet, a conveyance roller pair to convey the sheet from the image forming unit to the discharge roller pair, and a control unit to control a motor to switch a speed of the conveyance roller pair and the discharge roller pair between a first speed corresponding to the image forming speed and a second speed higher than the first speed. In first control, the speed is switched from the second to the first speed at timing at which a trailing end of the sheet reaches a first position. In second control, the speed is switched from the second to the first speed at timing at which a leading end of a subsequent sheet reaches a second position.