Image Forming Apparatus Sheet Feed Timing Control
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Solution Overview
Problem
Conventional image forming apparatuses face issues with inconsistent sheet feed timing due to varying stack heights of recording sheets, leading to unstable image transfer and reduced printing accuracy, especially when conveyance roller pairs are omitted between the sheet feed and transfer rollers.
Innovation Solution
An image forming apparatus that includes a sheet feeder with an elevating plate and a rotation drive mechanism, where the elevating plate swings vertically to align recording sheets with the sheet feed roller, and a conveyance controller measures sheet feed time to synchronize the sheet feed operation, ensuring consistent sheet feed timing and direct conveyance from the sheet feed roller to the transfer roller.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the elevating plate is moved vertically by rotation of gears, then the sheet feed roller can feed recording sheets, but the speed of vertical movement is low and sheet feed timing varies depending on the amount of recording sheets stacked
Solution Approach 1:
The patent replaces the gear-based mechanical vertical movement system with a direct drive system where the elevating plate is swung vertically by a drive mechanism that can control speed independently. This substitution allows for faster vertical movement while maintaining reliable sheet feed timing through coordinated control of the sheet feed roller and elevating plate movement.
2Volume of moving object
If conveyance roller pairs are omitted between sheet feed roller and transfer roller, then the apparatus size is reduced, but sheet feed timing varies depending on stack height and image transfer becomes unstable
Solution Approach 1:
The patent applies preliminary action by having the sheet feed roller feed the recording sheet to a predetermined position before the transfer roller operates. The elevating plate swings to the uppermost position in advance to ensure the sheet is properly positioned. This coordination ensures that even without intermediate conveyance roller pairs, the sheet transfer timing remains stable and reliable.
3Device complexity
If the sheet feed roller and elevating plate are driven by the same drive source, then the structure is simplified, but sheet feed timing varies depending on the number of recording sheets stacked
Solution Approach 1:
The patent applies dynamics by enabling independent control of the sheet feed roller and elevating plate movement. Although they can share a drive source, the system dynamically adjusts the timing and speed of each component based on the number of sheets stacked and the required feed timing. This dynamic coordination maintains consistent sheet feed timing while keeping the overall structure simplified.
Data Source
AI summary
An image forming apparatus feeds a recording sheet from a sheet feed roller, clamps the recording sheet between an image carrier and a transfer roller, transfers a toner image to the recording sheet from the image carrier while conveying the recording sheet, and fixes the transferred toner image on the recording sheet. Recording sheets are stacked on an elevating plate. An elevating plate swinging mechanism vertically swings the elevating plate. A rotation drive mechanism rotates the sheet feed roller in synchronism with the elevating plate swinging mechanism. A recording sheet detector detects a leading edge of each recording sheet fed from the sheet feed roller. A conveyance controller measures sheet feed time from starting a sheet feed operation to detecting the leading edge of the recording sheet. Based on the measured sheet feed time, the conveyance controller sets a sheet feed start timing of a next recording sheet.