Duplex Paper Skew Control via Variable Speed Transport
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Solution Overview
Problem
Conventional image forming apparatuses experience paper skewing during duplex printing, leading to poor print quality due to insufficient tension in the paper from the fixing unit to the transport rollers.
Innovation Solution
An image forming apparatus with a first transporting section for fixing and a second transporting section with a controlled higher speed and reduced transporting force, utilizing a switchback mechanism with a switchback roller and idle roller to gradually remove skew by adjusting friction coefficients and speeds to maintain paper tension.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the paper is advanced at increasing lower speed from upstream to downstream to prevent excessive tension, then the paper tension is reduced, but the paper becomes skewed with respect to the transport path
Solution Approach 1:
The patent applies dynamics by making the transporting speed variable rather than constant. The second transporting section dynamically adjusts its speed to be higher than the first transporting section during specific phases, creating a speed differential that actively manages paper tension and prevents skewing while maintaining alignment precision
Solution Approach 2:
The patent changes the speed parameter of the second transporting section relative to the first transporting section. By controlling the second section to operate at a higher speed (Vr ≤ 1.05×Vf), the system optimizes paper tension and prevents skewing without compromising alignment, resolving the contradiction between tension reduction and alignment maintenance
2Manufacturing precision
If the second transporting section operates at a higher speed than the first transporting section, then paper tension is maintained to prevent skewing, but the transporting force increases
Solution Approach 1:
The patent carefully balances two parameters: speed and transporting force. The second transporting section operates at a higher speed (up to 1.05×Vf) to maintain paper tension and prevent skewing, while simultaneously limiting the transporting force to no more than 1/4 of the first transporting section's force, thus resolving the contradiction between alignment precision and force application
3Strength
If the transporting force of the second transporting section is limited to 1/4 of the first transporting section, then paper damage is reduced, but the ability to maintain tension decreases
Solution Approach 1:
The patent resolves this contradiction by changing the speed parameter rather than relying solely on force. The second transporting section operates at a higher speed to generate the necessary tension maintenance capability through kinetic effects, while the transporting force remains limited to 1/4 of the first section, thus protecting paper integrity while maintaining alignment
Solution Approach 2:
The system uses dynamic speed adjustment in the second transporting section to compensate for the reduced transporting force. By operating faster, the second section maintains adequate paper tension and prevents skewing despite the force limitation, thereby preserving both paper integrity and alignment precision
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 removes paper skew, ensuring high print quality by maintaining proper tension and alignment throughout the printing process, particularly during duplex printing.
Implementation Method 1
The idle roller is in pressure contact with the transporting roller such that the idle roller and the transporting roller exert a transporting force on the recording medium
Implementation Method 2
The first transporting section is a fixing unit that fixes a developer deposited on the recording medium while also transporting the recording medium
Data Source
AI summary
An image forming apparatus includes a medium transporting mechanism. A first transporting section transports a recording medium on which an image is formed. A second transporting section receives the recording medium from the first transporting section and then further transports the recording medium. The second transporting section has a smaller transporting force than the first transporting section. A controller controls the second transporting section in such a way that the second transporting section transports the recording medium at a higher speed than the first transporting section.