Paper Thickness-Adaptive Feed Roller Speed Control for Skew Correction
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Solution Overview
Problem
In compact image forming apparatuses, the lack of an intermediate conveying roller pair leads to sheet skew and creasing issues due to insufficient space for bending correction, especially when handling thin and thick papers with different slip rates, resulting in improper image transfer.
Innovation Solution
A recording medium conveyer system with a feeding member, conveying member, driver, drive transmission member, selector, and controller that independently drives the feeding and conveying members, adjusts the driving sequence and speed based on paper thickness to correct skew and prevent creasing, using a selector to determine paper thickness and control the timing and speed of the feed roller relative to the registration roller pair.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the feed roller drives the sheet at a higher speed than the registration roller pair to handle thin sheets with higher slip rates, then thin sheets can be conveyed, but the thin sheets are bent and twisted between the nip portions, causing creasing and skew correction failure
Solution Approach 1:
The patent applies dynamics by making the drive transmission mechanism adjustable based on sheet thickness. The system dynamically changes the speed relationship between the feed roller and registration roller pair: for thin sheets, the feed roller speed is matched to the registration roller pair speed to prevent excessive bending; for thick sheets, the feed roller drives at higher speed to compensate for slip. This dynamic adjustment resolves the contradiction between handling thin sheets and maintaining sheet flatness.
Solution Approach 2:
The patent changes the speed parameter of the feed roller based on the detected sheet thickness. When a thin sheet is detected, the system reduces the feed roller speed to match the registration roller pair speed, preventing the sheet from being bent and twisted. This parameter change directly addresses the contradiction by adapting the conveying speed to the specific sheet type.
2Adaptability or versatility
If the feed roller continues driving after the registration roller pair starts to accommodate thick sheets with lower slip rates, then thick sheets can be conveyed, but thin sheets are conveyed at excessively high speeds, causing bending and creasing
Solution Approach 1:
The patent uses feedback by detecting sheet thickness and using this information to control the drive transmission mechanism. The thickness detection provides feedback that allows the system to adjust the feed roller speed appropriately: for thick sheets, the feed roller continues driving at higher speed; for thin sheets, the feed roller speed is reduced to match the registration roller pair. This feedback mechanism resolves the contradiction between accommodating thick sheets and preventing excessive speed for thin sheets.
Solution Approach 2:
The system dynamically adjusts the feed roller speed based on real-time sheet thickness detection. When a thin sheet is detected, the feed roller speed is dynamically reduced to match the registration roller pair speed, preventing excessive conveying speed and associated bending. This dynamic speed control resolves the contradiction between handling thick and thin sheets appropriately.
3Ease of operation
If the sheet is bent between the feed roller nip and registration roller pair nip to correct skew, then skew correction is achieved, but thin sheets lack sufficient space for bending, causing twisting and creasing
Solution Approach 1:
The patent changes the speed parameter of the feed roller to prevent excessive bending of thin sheets. By reducing the feed roller speed to match the registration roller pair speed when thin sheets are detected, the system minimizes the bending that occurs between the nip portions, thereby preventing twisting and creasing while still maintaining skew correction capability for thicker sheets.
Solution Approach 2:
The system dynamically adjusts the conveying speed to adapt to different sheet thicknesses. For thin sheets, the reduced speed difference between feed roller and registration roller pair minimizes bending, providing sufficient space for skew correction without causing twisting. This dynamic speed adjustment resolves the contradiction between skew correction and sheet flatness.
4Device complexity
If the intermediate conveying roller pair is omitted to compact the apparatus, then device complexity is reduced, but sufficient space for sheet bending is not provided, causing skew correction failure and creasing
Solution Approach 1:
The patent compensates for the omitted intermediate conveying roller pair by changing the speed parameters of the feed roller and registration roller pair. By precisely controlling the speed relationship between these components based on sheet thickness, the system achieves adequate bending space for skew correction without requiring the intermediate roller pair, thus maintaining compact structure while ensuring sheet flatness.
Solution Approach 2:
The dynamic speed control between the feed roller and registration roller pair replaces the function of the omitted intermediate conveying roller pair. By adjusting the speed difference dynamically based on sheet thickness, the system creates sufficient bending space for skew correction in the reduced conveyer structure, preventing creasing while maintaining compact design.
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 system effectively corrects sheet skew and prevents creasing across various paper thicknesses by optimizing the timing and speed of the feed roller relative to the registration roller pair, ensuring proper image transfer and reducing mechanical stress on the paper.
Implementation Method 1
a separator including a feed roller and a separation pad separates an uppermost sheet from other sheets loaded in the paper tray by friction and feeds the uppermost sheet toward a registration roller pair
Implementation Method 2
the sheet is contacted and stopped by the registration roller pair so that the sheet is bent between a nip portion formed between the feed roller and the separation pad and a nip portion formed by the registration roller pair
Implementation Method 3
The rotating registration roller pair rotates the intermediate conveying roller via the sheet to apply tension backward to the sheet, so as to correct skew of the sheet and prevent creasing of the sheet
Data Source
AI summary
In a recording medium conveyer, a driver drives a feeding member and a conveying member provided downstream from the feeding member in a recording medium conveyance direction independently. A controller stops driving the feeding member when a first time period elapses after a recording medium reaches the conveying member. When a selector judges that the thickness of the recording medium identifies the recording medium as thin paper, the controller does not drive the feeding member after the controller starts driving the conveying member, and when the selector judges that the recording medium has a thickness greater than a thickness of the recording medium that identifies the recording medium as thin paper, the controller restarts driving the feeding member no later than when the controller starts driving the conveying member.