Variable Conveying Force in Duplex Sheet Delivery Rollers
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Solution Overview
Problem
Existing image forming apparatuses face challenges in achieving high stacking regularity and sufficient skew feed correction during duplex printing, particularly due to excessive conveying force of delivery rollers in skew feed correction mechanisms.
Innovation Solution
An image forming apparatus with a discharging roller pair that adjusts its conveying force, featuring a skew feed correction member in the re-conveying path with a lower conveying force than the discharging roller pair, to correct skew feed and enhance stacking regularity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the conveying force of the delivery rollers is increased to improve sheet delivery reliability, then the sheet delivery reliability is improved, but the skew feed correction effect deteriorates because the leading edge passes through the skew-correcting portion without sufficient alignment
Solution Approach 1:
The patent applies the dynamics principle by making the conveying force of the delivery rollers variable rather than constant. The conveying force is dynamically adjusted based on the operational phase: a first conveying force is applied during normal sheet delivery to ensure reliable delivery, while a second, smaller conveying force is applied during skew feed correction to enable proper alignment. This dynamic adjustment resolves the contradiction between delivery reliability and skew correction precision.
Solution Approach 2:
The patent implements parameter changes by modifying the conveying force parameter of the delivery rollers according to different operational requirements. The control unit changes the conveying force from a first value (for delivery) to a second value (for skew correction), allowing the system to optimize performance for each specific function and resolve the trade-off between reliable delivery and precise skew correction.
2Manufacturing precision
If the conveying force of the delivery rollers is decreased to improve skew feed correction effect, then the skew feed correction precision is improved, but the sheet delivery reliability deteriorates
Solution Approach 1:
The system dynamically adjusts the conveying force parameter based on the operational phase. During skew feed correction, a smaller conveying force is applied to enable precise alignment, while during normal delivery, a larger conveying force ensures reliable sheet transport. This dynamic behavior resolves the contradiction between skew correction precision and delivery reliability.
Solution Approach 2:
The control unit changes the conveying force parameter between two distinct values: a first conveying force for reliable delivery and a second, smaller conveying force for precise skew correction. This parameter switching allows the system to optimize for the current operational requirement, resolving the trade-off between the two competing objectives.
3Manufacturing precision
If a skew feed correction mechanism is added to correct skew feed during switchback operation, then the skew feed correction capability is improved, but the device complexity increases
Solution Approach 1:
The patent applies the universality principle by enabling the delivery rollers to perform multiple functions: normal sheet delivery and skew feed correction. By controlling the rotation direction and conveying force of the same delivery rollers, the system achieves skew correction capability without adding separate correction mechanisms, thus improving skew correction capability while minimizing increases in device complexity.
Solution Approach 2:
The delivery rollers perform skew feed correction as a self-service function by utilizing their own rotational control capabilities. The control unit directs the delivery rollers to rotate in reverse and apply a reduced conveying force, allowing the same component to correct skew without requiring external correction devices, thereby improving skew correction capability while avoiding additional system complexity.
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
The solution effectively enhances stacking regularity and achieves a high skew feed correction effect by controlling the conveying force, ensuring proper alignment and correction of sheets during duplex printing.
Implementation Method 1
sheets are conveyed to a fixing unit by a conveying roller pair, and thereafter, are delivered to a delivery tray by a delivery roller pair
Data Source
AI summary
An image forming apparatus has an image forming unit that forms an image on a sheet; a discharging roller pair that discharges the sheet, on which the image is formed, onto a stacking portion with a rotation in a first direction, and conveys the sheet to a re-conveying path for conveying the sheet to the image forming unit again with a rotation in a second direction opposite to the first direction; and a skew feed correction member that is provided in the re-conveying path, and contacts against a leading edge of the sheet conveyed by the rotation in the second direction to correct skew feed of the sheet. The sheet conveying force when contacting the leading edge of the sheet against the skew feed correction member is smaller than sheet conveying force of the discharging roller pair when discharging the sheet onto the stacking portion.