Image Forming Apparatus With Side-End Sheet Alignment
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Solution Overview
Problem
Existing image forming apparatuses face issues with significant oblique movement and positional deviation of sheets during the formation of images on both surfaces, particularly when reversing and re-feeding sheets, leading to reduced quality and potential creasing.
Innovation Solution
The apparatus incorporates a registration unit with a registration roller pair and a moving mechanism to correct oblique movement by forming a loop with the sheet's leading end, and a reversing unit with a reversing roller pair to adjust the sheet's position in the widthwise direction, using sensors to detect end positions and control motors for precise movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the sheet is fed through the reversing portion and re-feeding portion to form an image on the second surface, then double-sided imaging is achieved, but the sheet position in the widthwise direction deviates significantly
Solution Approach 1:
The patent applies preliminary action by detecting the sheet's widthwise position before the reversing and re-feeding operations, then pre-calculating and applying the necessary correction amount. The side end detecting portion detects the position in advance, and the control unit determines the correction amount before the actual reversing operation occurs, allowing precise position correction to be applied subsequently.
Solution Approach 2:
The patent implements feedback by using the side end detecting portion to continuously monitor the sheet's widthwise position during the feeding and reversing operations. The control unit receives this detection information and adjusts the moving means accordingly, creating a closed-loop control system that corrects position deviations based on actual measured values rather than relying solely on predetermined parameters.
2Manufacturing precision
If the movement amount of the side end portion is increased to correct position deviation, then position accuracy is improved, but the degree of oblique movement becomes large causing sheet distortion
Solution Approach 1:
The patent applies dynamics by making the correction amount variable rather than fixed. The control unit dynamically adjusts the correction amount based on the actual position detected by the side end detecting portion. This allows the system to apply only the necessary correction amount needed to achieve accurate positioning, avoiding excessive correction that would cause sheet distortion while still achieving precise position control.
3Manufacturing precision
If the sheet is nipped by the registration roller pair for position correction, then oblique movement is corrected, but the sheet may experience creasing and resistance issues
Solution Approach 1:
The patent applies parameter changes by adjusting the nipping force and correction speed parameters during the position correction process. The control unit controls the moving means to move the registration roller pair at an appropriate speed while applying suitable nipping force, thereby achieving effective oblique movement correction without creating excessive resistance or sheet creasing.
Data Source
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AI summary
The present invention relates to an image forming apparatus (1) comprising: an image forming portion (N) configured to form an image on a sheet (S); a conveying roller pair (131) configured to nip and convey the sheet of which the image is formed on a first surface by the image forming portion; a sheet detecting portion (138) configured to detect the sheet conveyed by the conveying roller pair; a side end of the sheet detecting portion (139) configured to detect a position of the side end of the sheet (S) conveyed by the conveying roller pair (131) with respect to a widthwise direction (W); a reversing roller pair (132) configured to reverse the sheet (S) conveyed by the conveying roller pair by conveying in a first direction (A1) while nipping the sheet (S) and then by conveying in a second direction (A2) opposite to the first direction, and a moving means of the reversing roller pair (137) configured to move the sheet (S) in the widthwise direction (W) in a state in which the sheet (500) is nipped by the reversing roller pair (132), wherein the moving means of the reversing roller pair (137) moves the sheet in the widthwise direction on the basis of a detection result of the side end of the sheet detecting portion, and wherein the side end of the sheet detecting portion (139) is disposed in a downstream side of the sheet detecting portion (138) in the first direction.