Sheet Conveyance Speed Control for Image Transfer Vibration
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Solution Overview
Problem
Conventional image forming apparatuses fail to effectively correct sub scanning obliqueness during image transfer, leading to image defects due to misalignment and vibration issues, particularly with long sheets, as existing registration displacement control techniques only address registration displacement before image transfer and not during the process.
Innovation Solution
An image forming apparatus and conveyance control method that control the displacement speed of the sheet conveying member to be lower than before image transfer, preventing vibration transmission to the transfer section and correcting sub scanning obliqueness by maintaining a loop in the sheet between the registration and transfer nips.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sheet conveying member is displaced at high speed to correct registration displacement, then registration accuracy is improved, but vibration is transmitted to the transfer section causing image defects
Solution Approach 1:
The patent applies dynamics by changing the displacement speed of the sheet conveying member based on the operational phase. During image transfer, the displacement speed is reduced to prevent vibration transmission, while during non-transfer phases, normal speed can be maintained. This dynamic speed adjustment resolves the contradiction between achieving registration accuracy and preventing harmful vibration transmission to the transfer section.
2Device complexity
If registration displacement control is performed only before image transfer, then the control system is simple, but sub scanning obliqueness during transfer cannot be corrected
Solution Approach 1:
The patent applies preliminary action by performing registration displacement control before image transfer begins, and then maintaining a loop in the sheet during transfer. This preliminary positioning combined with loop maintenance during transfer allows correction of sub scanning obliqueness without requiring complex real-time control during the transfer process itself, thus balancing simplicity and precision.
3Object-affected harmful factors
If the displacement speed is reduced during image transfer, then vibration transmission is prevented, but registration correction capability is reduced
Solution Approach 1:
The patent applies segmentation by dividing the sheet conveyance process into distinct phases: before image transfer where registration displacement control is actively performed, and during image transfer where the loop is maintained at reduced speed. This temporal segmentation allows full registration correction capability before transfer while preventing vibration during transfer, resolving the contradiction between correction capability and vibration prevention.
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
An image forming apparatus (1) includes: a transfer section (421, 423B, 424) that transfers an image onto a sheet (S); a sheet conveying member (53a) that conveys the sheet (S), the sheet conveying member (53a) being provided upstream of the transfer section (421, 423B, 424) in a sheet conveyance direction; and a control unit (100) that controls displacement of the sheet conveying member (53a) so that the sheet (S) is displaced along a width direction of the sheet (S). The control unit (100) sets a displacement speed (VI) of the sheet conveying member (53a) for the sheet (S) during transfer of the image by the transfer section (421, 423B, 424) to be lower than the displacement speed of the sheet conveying member (53a) for the sheet (S) before the transfer of the image by the transfer section (421, 423B, 424).