Transfer Roller Velocity Control for Shock Jitter Suppression
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Solution Overview
Problem
Current transfer devices in electrophotographic image forming apparatuses face challenges in suppressing image quality reduction, such as shock jitter, when handling thicker recording media like cardboard, due to rapid nipping pressure increases and oscillations in the transfer process.
Innovation Solution
A transfer device with a moving unit that controls the transfer roller's movement between contact and separation states, adjusting its velocity to reduce the impact of thicker media by slowing down the contact operation and increasing the pressing operation velocity, ensuring the nipping pressure is established before the image-forming region enters the transfer nipping portion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the transfer roller is quickly pressed against the intermediate transfer belt to generate nipping pressure, then the transfer operation is efficient and productive, but the rapid pressure increase causes shock jitter and image quality degradation when handling thicker media
Solution Approach 1:
The cam profile is designed to perform preliminary action by first bringing the transfer roller into contact with the intermediate transfer belt at a location upstream of the image-forming region, establishing nipping pressure before the media enters the transfer zone. This preliminary contact occurs in the non-image-forming region, allowing pressure stabilization before image transfer begins, thereby preventing shock jitter while maintaining efficiency
Solution Approach 2:
The transfer operation is segmented into distinct phases by the cam profile: a contact phase where the roller approaches and contacts the belt upstream, and a pressing phase where full nipping pressure is applied. This segmentation allows the contact operation to occur before the image-forming region enters, separating the pressure-establishment function from the image-transfer function, thus eliminating shock jitter while preserving productivity
2Reliability
If the transfer roller is separated from the intermediate transfer belt during waiting time, then the transfer device is protected from deterioration, but the frequent contact and separation operations increase mechanical wear and complexity
Solution Approach 1:
The moving unit employs dynamic cam mechanisms that enable smooth, controlled contact and separation of the transfer roller from the intermediate transfer belt. The cam profile continuously adjusts the roller position, providing gradual engagement and disengagement rather than abrupt movements, which reduces mechanical shock and wear while maintaining the necessary separation during waiting periods to prevent device deterioration
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces the rapid increase in nipping pressure and oscillations, thereby enhancing the suppression of image quality reductions like shock jitter, even at higher sheet conveyance velocities, and maintains image quality by stabilizing the nipping pressure before the image-forming region passes through.
Implementation Method 1
a biasing unit that biases the secondary transfer roller toward the intermediate transfer belt
Implementation Method 2
The cams are plate cams provided in a rotary shaft that rotatably supports a secondary-transfer opposing roller
Implementation Method 3
a state of a predetermined nipping pressure being generated in a secondary transfer nipping portion formed by the intermediate transfer member and the secondary transfer roller
Data Source
AI summary
A transfer device includes an image carrier, a transfer roller, and a moving unit. The moving unit moves the transfer roller between a nip formation state in which the transfer roller forms a transfer nipping portion in contact with the image carrier and a separated state in which the transfer roller is separated from the image carrier. In a contact operation of bringing the transfer roller into contact with the image carrier via the recording medium, the moving unit moves the transfer roller toward the image carrier at a moving velocity slower than that in a pressing operation of generating a predetermined nipping pressure by further moving the transfer roller toward the image carrier after the contact operation. The moving unit causes the recording medium to enter the transfer nipping portion in the contact operation.