Sheet Feeding Mechanism for Intermittent Conveyance and Skew Correction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing image forming apparatuses face reduced throughput due to the need to completely discharge one sheet before feeding the next, and they often fail to correct skew in subsequent pages, leading to undesirable image positioning or paper jams.
Innovation Solution
An image forming apparatus with a sheet conveying system that includes a sheet feed roller, conveyor rollers, and a controller to intermittently rotate the conveyor rollers, allowing the leading edge of the next sheet to collide with the conveyor unit while forming an image on the previous sheet, and correcting skew before completing the image formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the image forming apparatus waits for complete discharge of the preceding sheet before feeding the next sheet, then sheet discharge reliability is improved, but throughput decreases
Solution Approach 1:
The next sheet is fed to the sheet conveying unit in advance while the recording unit is still forming an image on the current sheet. This preliminary action of feeding the next sheet allows the system to prepare for the subsequent operation without waiting for the current sheet to be completely discharged, thereby increasing throughput while maintaining discharge reliability through controlled sequential operations.
2Productivity
If the sheet conveying unit continuously conveys sheets, then throughput is improved, but skew correction capability deteriorates
Solution Approach 1:
The sheet conveying unit operates intermittently rather than continuously. It conveys a sheet to the recording unit, holds it there during image formation, then conveys the next sheet while the previous sheet is being processed. This periodic action pattern allows the system to maintain high throughput through overlapping operations while providing sufficient time for skew correction on each individual sheet before recording.
Solution Approach 2:
The leading edge of the next sheet is positioned and collides with the sheet conveying unit in advance while the current sheet is being processed. This preliminary positioning action allows the system to prepare the next sheet for accurate alignment before the current recording operation completes, ensuring skew correction is performed without sacrificing throughput.
3Speed
If the sheet feed roller rotates continuously to feed sheets, then feeding speed is improved, but control precision for sheet positioning deteriorates
Solution Approach 1:
The sheet feed roller operates periodically, rotating to feed sheets at high speed when needed, then remaining stationary during the holding and recording phases. This periodic operation pattern allows the roller to maintain high feeding speed during the feeding phase while providing precise positioning control during the holding phase when the roller does not rotate, resolving the contradiction between speed and 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
This approach enhances throughput by allowing continuous printing without waiting for sheet discharge and ensures accurate image placement by correcting sheet skew before forming images on subsequent pages, thereby reducing paper jams and improving print quality.
Implementation Method 1
a sheet feeding unit comprising a sheet feed roller configured to feed a first sheet of the plurality of sheets from the tray through the sheet conveying path
Implementation Method 2
a sheet conveying unit comprising a conveyor roller configured to rotate intermittently, and to intermittently hold the plurality of sheets at the sheet holding position
Data Source
AI summary
An image forming apparatus includes a tray, a sheet conveying path through which sheets are conveyed, a sheet feeding unit including a sheet feed roller for feeding a first sheet to a sheet holding position, a sheet conveying unit having a conveyor roller that intermittently rotates and holds the sheets. The sheet conveying unit is upstream from a recording position, and downstream from the sheet feeding unit. The image forming apparatus also includes a recording unit, and a controller. The recording unit forms an image onto the first sheet while the conveyor roller is not rotating. The sheet feeding unit feeds a leading edge of a second sheet to the sheet conveying unit and maintains the leading edge of the second sheet colliding against the sheet conveying unit at the sheet holding position by rotating the sheet feed roller prior to completing image formation on the first sheet.