Secondary Transfer Roller Position Switching for Shock Jitter Reduction
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Solution Overview
Problem
Image forming apparatuses face challenges in reducing shock jitter-induced abnormal images due to speed differences between the intermediate transfer belt and photoconductor, leading to uneven image density and horizontal streaks, especially when the leading or trailing end of the recording material enters or exits the secondary transfer portion.
Innovation Solution
An image forming apparatus with a contact-separation mechanism that switches the position of the secondary transfer roller between a nipping and separating position based on specified abnormal image reduction conditions, using a control circuit to adjust the operation timing and gap size to mitigate shock jitter impacts, and prioritizing transfer pressure and image pattern perception to minimize abnormal images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the secondary transfer member maintains constant contact with the intermediate transfer member during recording material conveyance, then transfer reliability is improved, but shock jitter occurs when the leading or trailing end enters or exits the secondary transfer portion, causing abnormal images
Solution Approach 1:
The patent applies the dynamics principle by making the contact state between the secondary transfer member and intermediate transfer member variable rather than fixed. The switching unit dynamically changes the contact state between a first state (contacting to ensure transfer reliability) and a second state (separated to eliminate shock jitter). This allows the system to adapt to different operational phases: maintaining contact during stable transfer and separating during entry/exit phases when shock jitter would occur.
Solution Approach 2:
The patent implements periodic action through the switching unit that periodically alternates between contact and separation states. The control unit triggers periodic switching operations: separating before the leading end enters the secondary transfer portion, contacting when the leading end is within the portion, and separating again when the trailing end exits. This periodic modulation of the contact state prevents continuous shock jitter while maintaining transfer reliability during critical phases.
2Object-affected harmful factors
If the secondary transfer member separates from the intermediate transfer member to reduce shock jitter, then abnormal images are reduced, but transfer reliability may deteriorate due to insufficient transfer pressure
Solution Approach 1:
The patent applies preliminary action by performing separation operations in advance before shock jitter would occur and recovery operations after the critical transfer phase. Specifically, the switching unit separates before the leading end enters the secondary transfer portion (preventing anticipated shock jitter) and maintains contact during the actual transfer when the recording material is within the secondary transfer portion. This timing strategy ensures transfer reliability is maintained while preventing abnormal images.
Solution Approach 2:
The system dynamically adjusts the contact state based on the position of the recording material. The control unit monitors whether the leading or trailing end is within the secondary transfer portion and triggers switching operations accordingly. This dynamic response ensures that separation occurs only when it will prevent abnormal images without compromising transfer reliability during the critical transfer window.
3Object-affected harmful factors
If the moving speed of the secondary transfer member is reduced to slow down contact operation, then shock jitter is mitigated, but productivity decreases due to slower transfer process
Solution Approach 1:
The patent uses periodic action to intermittently reduce speed only when necessary. The switching unit periodically slows down the secondary transfer member's movement during critical phases (when leading or trailing ends enter or exit the secondary transfer portion) to mitigate shock jitter, then restores normal speed during stable transfer phases. This periodic speed modulation reduces abnormal images while maintaining overall productivity by minimizing speed reduction duration.
Solution Approach 2:
The system dynamically adjusts the moving speed of the secondary transfer member based on real-time position detection. The control unit commands speed reduction only when the leading or trailing end is detected within the secondary transfer portion, and maintains normal speed during other phases. This dynamic speed control mitigates shock jitter during critical transitions while preserving productivity during stable operation phases.
Data Source
AI summary
An image forming apparatus includes a latent image bearer, a toner image forming unit, an intermediate transfer member, a primary transfer member, a secondary transfer member, a switching unit, and control circuitry. The toner image forming unit forms toner images on the latent image bearer. The primary transfer member transfers the toner images on the latent image bearer onto the intermediate transfer member. The secondary transfer member transfers the toner images on the intermediate transfer member onto recording materials. The switching unit switches a position of one of the secondary transfer member and the intermediate transfer member between a first and a second position. The control circuitry controls at least one of a first and a second operation. The control circuitry changes at least one of the first and the second operation when the toner images satisfy a specified abnormal image reduction condition at a first and a second timing.