Sheet Conveyance Skew Correction via Width-Adaptive Control
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Solution Overview
Problem
Conventional image forming apparatuses face challenges in accurately correcting skew-feed issues for sheets of varying widths, leading to reduced conveyance efficiency and potential sheet damage during skew-feed correction, as the conveying force and timing of skew-feed correction rollers are not adequately adjusted for different sheet sizes.
Innovation Solution
A sheet conveying apparatus that adjusts the loop control time and skew-correction conveyance amount based on the sheet's width size and basis weight to ensure reliable skew-feed correction, using a combination of through roller and divided roller types to maintain conveyance stability and prevent sheet buckling, with independent control of sheet discharge and skew-feed correction rollers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the conveying roller conveys sheets with fixed conveying force, then wide sheets can be conveyed stably, but narrow sheets experience increased skew-feed and reduced conveyance efficiency
Solution Approach 1:
The patent applies dynamics by making the conveying force adjustable based on sheet width. The control unit dynamically changes the rotation speed of the conveying roller according to the detected sheet width, ensuring optimal conveying force for each sheet size. This resolves the contradiction by allowing the system to adapt its conveying characteristics rather than using a fixed conveying force that cannot simultaneously optimize for both wide and narrow sheets.
Solution Approach 2:
The patent changes the parameter of conveying force (rotation speed of conveying roller) based on sheet width. The control unit adjusts the rotation speed parameter according to the sheet width detected by the sensor, thereby optimizing the conveying force for each sheet size. This parameter adaptation allows the system to maintain conveyance stability for wide sheets while preventing excessive skew-feed for narrow sheets.
2Reliability
If the skew-feed correction roller starts rotation after a fixed predetermined time, then wide sheets can be corrected properly, but narrow sheets may not be sufficiently aligned
Solution Approach 1:
The patent applies dynamics by making the delay time dynamic rather than fixed. The control unit adjusts the delay time before the skew-feed correction roller starts rotation based on the sheet width detected by the sensor. For narrow sheets, a longer delay time is applied to allow sufficient alignment, while for wide sheets, a shorter delay time is used. This dynamic adjustment resolves the contradiction between correction reliability and conveyance time.
Solution Approach 2:
The patent changes the time parameter (delay time before correction roller rotation) based on sheet width. The control unit modifies this temporal parameter according to the sheet width, ensuring that narrow sheets receive adequate alignment time while wide sheets maintain efficient conveyance. This parameter adaptation resolves the contradiction between sufficient skew-feed correction and minimal conveyance time.
3Reliability
If the skew-feed correction roller starts rotation earlier to align narrow sheets, then narrow sheets are corrected properly, but wide sheets may be damaged due to excessive loop formation
Solution Approach 1:
The patent applies dynamics by making the correction timing adaptive rather than fixed. The control unit dynamically determines when the skew-feed correction roller should start rotation based on real-time sheet width detection. This prevents narrow sheets from being damaged by excessive skew-feed while preventing wide sheets from suffering damage due to excessive loop formation, thereby resolving the contradiction between correction reliability and sheet damage prevention.
Solution Approach 2:
The patent changes the timing parameter (when correction roller starts rotation) based on sheet width. By adjusting this critical timing parameter according to sheet dimensions, the system ensures that narrow sheets receive sufficient alignment time without causing excessive loop formation in wide sheets. This parameter adaptation prevents both types of sheet damage while maintaining correction effectiveness.
4Productivity
If the conveying roller rotates faster to improve productivity, then conveyance speed increases, but skew-feed amount increases for narrow sheets
Solution Approach 1:
The patent applies dynamics by making the conveying speed adjustable rather than fixed. The control unit dynamically modifies the rotation speed of the conveying roller based on the detected sheet width. For narrow sheets, the speed is reduced to minimize skew-feed, while for wide sheets, the normal speed is maintained to ensure productivity. This dynamic speed adjustment resolves the contradiction between productivity and skew-feed correction reliability.
Solution Approach 2:
The patent changes the speed parameter of the conveying roller based on sheet width. The control unit adapts the conveying speed parameter to match the sheet dimensions, ensuring that narrow sheets are conveyed at a speed that minimizes skew-feed while wide sheets are conveyed at optimal productivity speeds. This parameter adaptation resolves the contradiction between conveyance efficiency and skew-feed correction reliability.
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
Ensures reliable skew-feed correction across various sheet widths, preventing sheet damage and maintaining printing accuracy and quality, while also supporting miniaturization and cost reduction in image forming apparatuses.
Implementation Method 1
The sheet conveyed by the conveying roller receives a sliding friction caused by a guide.
Implementation Method 2
The leading edge of the sheet strikes the stopped skew-feed correction roller, whereby the leading edge of the sheet is aligned by the skew-feed correction roller
Data Source
Figure 1
Figure 2A~2C
Figure 3A~3C
AI summary
A sheet conveying apparatus, including: a conveyance portion configured to convey a sheet along a conveyance path; a skew-feed correction member (29, 42, 23) positioned in the conveyance path such that a leading edge of the sheet conveyed by the conveyance portion contacts the skew-feed correction member to correct a skew-feed of the sheet; a receiving portion (200a) configured to receive information indicative of the width of the conveyed sheet, the width being in a direction orthogonal to a sheet conveyance direction; and a control portion (200) configured to adjust a skew-correction conveyance amount of the conveyance portion applied to correct the skew-feed of the sheet by the skew-feed correction member, wherein the skew-correction conveyance amount is adjusted based on the information received by the receiving portion such that the skew-correction conveyance amount is set to be larger for a sheet of smaller width compared to a sheet of greater width.