Continuous Sheet Conveyance Control for Stable Image Reading
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Image reading devices struggle to maintain stable conveyance speed when applied to long or continuous sheets, leading to unstable reading performance due to the influence of high-torque fixing rollers on downstream conveyance rollers.
Innovation Solution
An image forming system with a controller that performs speed control on the first conveyance section and torque control on the second conveyance section, applying tension to the recording medium by driving the second conveyance section at a predetermined target conveyance speed while keeping the first conveyance section in a stop state, determining the target torque when it is saturated, and performing torque control based on this target.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the speed of conveyance rollers on the downstream side is controlled to be slightly higher than the fixing roller, then tension is applied to maintain reading height, but the conveyance speed becomes unstable due to influence from the high driving force of the fixing roller
Solution Approach 1:
The patent changes the control parameter from speed to torque for the conveyance rollers. By controlling the torque of the conveyance rollers to be lower than the torque of the fixing roller, the system maintains stable conveyance speed while still applying necessary tension to the sheet, resolving the instability caused by the high driving force of the fixing roller.
2Stability of the object's composition
If the conveyance roller speed is increased to maintain tension on the sheet, then reading height is maintained, but reading performance deteriorates due to unstable conveyance speed
Solution Approach 1:
The patent transitions from speed control to torque control for the conveyance rollers. This parameter change allows the system to maintain stable conveyance speed (improving reading performance) while still applying adequate tension to maintain reading height consistency through the torque relationship with the fixing roller.
3Reliability
If the fixing roller uses high driving force for stable conveyance, then sheet conveyance reliability is improved, but downstream conveyance rollers cannot maintain target speed due to the influence of the fixing roller's high torque
Solution Approach 1:
The patent changes the control parameter of downstream conveyance rollers from speed to torque. By setting the torque of conveyance rollers to be lower than the torque of the fixing roller, the system allows the fixing roller to provide high driving force for reliable sheet conveyance while the downstream rollers maintain their target speed through torque control, preventing speed instability.
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
An image forming system includes: an image forming unit that forms an image on a recording medium that is a continuous sheet or a long sheet; a first conveyance section that conveys the recording medium on a first conveyance path on which the image forming unit is placed; an image reading section that reads an image formed on the recording medium in a second conveyance path on a downstream side of the first conveyance path in a conveyance direction of the recording medium; a second conveyance section that conveys the recording medium on the second conveyance path; and a controller that performs speed control on a drive source of the first conveyance section and performs torque control on a drive source of the second conveyance section.