Dynamic Pressure Control for Transfer Nip Impact Reduction
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Solution Overview
Problem
In electrophotographic image forming apparatuses, speed fluctuations of the intermediate transfer body cause deviations in superimposing positions of color toner images, leading to color irregularity and deteriorated image quality, particularly due to unsteady impact forces when sheets enter or leave the transfer nip, which existing technologies struggle to effectively suppress.
Innovation Solution
A pressure device with a first and second pressing unit, a driving unit, distance detection, and control unit that adjusts the distance between the units based on detected sheet presence and thickness to apply a predetermined pressure, minimizing impact forces by setting target distances and pressures accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If pressure is applied to the sheet medium during transfer, then transfer quality is improved, but impact forces occur when sheets enter or leave the transfer nip
Solution Approach 1:
The system detects the leading edge of the sheet before it enters the transfer nip and preemptively reduces the pressure from the pressing units. This preliminary anti-action prevents the impact force from occurring in the first place, rather than reacting to it after it happens. The pressure is restored to normal levels after the sheet has fully entered the nip region.
Solution Approach 2:
The sheet detection mechanism performs preliminary detection of the sheet's presence and position before the actual transfer process begins. This allows the control system to prepare the pressing units by reducing pressure in advance, ensuring smooth sheet entry without impact forces while still maintaining transfer quality when needed.
2Stability of the object's composition
If constant pressure is maintained in the transfer nip, then transfer consistency is improved, but speed fluctuations of the intermediate transfer body cause image displacement
Solution Approach 1:
The system transitions from static constant pressure to dynamic pressure control. The pressure applied by the pressing units is continuously adjusted based on real-time detection of sheet presence and position. This dynamic approach allows the system to maintain transfer consistency through adaptive pressure while preventing image displacement by reducing pressure during critical entry and exit phases.
Solution Approach 2:
The sheet detection mechanism provides continuous feedback about sheet position and speed to the control system. This feedback loop enables real-time adjustments to the pressing unit pressure, ensuring that pressure is applied consistently during the transfer phase while being reduced when sheet speed fluctuations occur, thereby maintaining both transfer consistency and image position accuracy.
Data Source
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AI summary
A pressure device applies pressure to a sheet medium on part of a surface of which an image bearer is formed. The pressure device includes: a driving unit that changes a distance between a first pressing unit and a second pressing unit; a control unit that controls the driving unit such that the distance between the first pressing unit and the second pressing unit becomes a set target value; and a target setting unit that sets the target value to a first distance that is larger than a thickness of the sheet medium when the sheet medium is not present between the first pressing unit and the second pressing unit, and sets the target value to a second distance for applying a target pressure to the sheet medium when the sheet medium and the image bearer are present between the first pressing unit and the second pressing unit.