Index Sheet Post-Processing Using Duplex Switchback Alignment
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Solution Overview
Problem
Existing image forming apparatuses face challenges in accurately aligning index sheets for post-processing due to protruding index portions, especially when a dedicated reverse discharge mechanism is absent, leading to incomplete or incorrect post-processing.
Innovation Solution
The apparatus includes a sheet feeding mechanism, image forming mechanism, double-sided transport mechanism, and post-processing units that allow controllers to determine the order of image formation and switchback based on the type of post-processing unit, enabling alignment of index portions with the post-processing position without a dedicated reverse discharge mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a post-processing unit that performs post-processing on a trailing end is mounted, then it is reasonable to form a punch hole on the trailing end when an index portion is located on a trailing end side, but post-processing cannot be performed when the index portion is located on a leading end side without a reverse discharge mechanism
Solution Approach 1:
The patent applies inversion by changing the mounting position of the post-processing unit from the trailing end to the leading end of the print sheet. This allows the post-processing unit to effectively process the trailing end of the sheet by utilizing the reversed transport direction created by the double-sided transport mechanism, thereby providing versatile post-processing capability without requiring a dedicated reverse discharge mechanism.
Solution Approach 2:
The double-sided transport mechanism serves multiple functions: it transports print sheets for double-sided printing and simultaneously enables index sheets to be switched back for proper alignment with post-processing units. This multi-functionality eliminates the need for separate reverse discharge mechanisms, reducing device complexity while maintaining adaptability.
2Productivity
If an index sheet is set with the index portion on a trailing end side, then printing can be performed, but accurate detection of the leading end position cannot be achieved due to the protruding index portion
Solution Approach 1:
The patent inverts the orientation handling by using the double-sided transport mechanism to switch back index sheets, effectively reversing their transport direction. This allows the index portion that would normally interfere with leading end detection to be repositioned, enabling accurate detection and processing.
3Adaptability or versatility
If a reverse discharge mechanism is added to switch back index sheets, then post-processing can be performed on trailing end, but device complexity increases
Solution Approach 1:
The patent makes the double-sided transport mechanism serve dual purposes: transporting sheets for double-sided printing and switching back index sheets for post-processing alignment. This eliminates the need for a separate reverse discharge mechanism, maintaining adaptability while reducing device complexity.
Solution Approach 2:
The patent merges the function of the double-sided transport mechanism with the index sheet switching back function. By combining these two functions into a single mechanism, the patent avoids adding the complexity of a dedicated reverse discharge mechanism while maintaining full post-processing capability.
Data Source
AI summary
An image forming apparatus comprises a sheet feeding mechanism that feeds a print sheet; an image forming mechanism capable of forming a first image on one surface of the print sheet and allowing the print sheet to pass through the image forming mechanism, and forming a second image on the other surface of the print sheet when the print sheet that has passed through the image forming mechanism is switched back and passes through the image forming mechanism again; a double-sided transport mechanism that switches back the print sheet on which the first image is formed, and guides the print sheet to the image forming mechanism again; a post-processing unit mounter on which a post-processing unit that performs post-processing on a leading end or a trailing end of a print sheet to be discharged can be mounted; and one or more controllers that control a print job, wherein when executing a print job in which at least a part of print sheets is an index sheet, and a post-processing function is set, the one or more controllers determine whether post-processing is to be performed, the order of an image to be formed, and whether to switch back a print sheet by using the double-sided transport mechanism according to a type of the mounted post-processing unit as to whether post-processing is to be performed on a leading end or a trailing end of the print sheet.