Back Curl Correction Structure for Image Forming Apparatus
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Solution Overview
Problem
Electrophotographic image forming apparatuses experience significant back curl issues due to temperature differences during the fixing process, leading to sheet curl and instability in sheet conveyance, which can result in damaged sheets and uneven toner images.
Innovation Solution
An image forming apparatus with a back curl correction structure that includes a drive roller, a driven roller, and a guide member, which forms an auxiliary nip portion to gently bend the recording sheet and correct the curl, while a guide moving device adjusts the guide member's position to minimize contact and prevent damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the heating member is formed to have a lower thermal capacity for a quick rise in temperature, then energy consumption is reduced and warm-up time is shortened, but the difference in temperature between the heating member and pressure roller increases, causing greater back curl
Solution Approach 1:
The system performs preliminary warming of the pressure roller before the heating member reaches full temperature, preparing the sheet feeding path in advance to compensate for the temperature difference that will exist during quick heating operation
Solution Approach 2:
A warming roller is introduced as an intermediary component between the pressure roller and the sheet, specifically designed to warm the sheet feeding path and reduce back curl caused by the temperature difference in quick-rise heating systems
2Reliability
If a back curl correction structure with a guide member is added to correct sheet curl, then sheet conveyance stability is improved, but the complexity of the device increases
Solution Approach 1:
The guide member is designed to be movable rather than fixed, allowing it to dynamically adjust its position based on sheet conditions. This reduces the need for additional complex mechanisms while maintaining correction effectiveness
Solution Approach 2:
The system changes the positional parameter of the guide member to optimize back curl correction. By adjusting the guide member's position, the system achieves effective correction without adding complex mechanical structures
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
The solution effectively reduces back curl, stabilizes sheet conveyance, and minimizes damage to the recording sheet and toner image, allowing for proper stacking and preventing image rubbing and gloss flaws.
Implementation Method 1
a drive roller disposed at a side where a back curl is generated on the recording sheet in the fixing nip portion; a driven roller disposed at a side where the recording sheet is heated; an auxiliary nip portion between the drive roller and the driven roller, to press and feed the recording sheet auxiliary
Implementation Method 2
The fixing device includes a heating member and a pressure roller that press against each other to form a fixing nip, through which the recording sheet on which an unfixed toner image is borne passes. The recording sheet is pressed and heated when passing through the fixing nip
Implementation Method 3
after passing through the fixing nip, moisture contained in the recording sheet evaporates more from the front surface of the recording sheet than from the back side
Data Source
AI summary
An image forming apparatus includes an image forming device to transfer an image to a recording sheet; a fixing device to feed the recording sheet and fix the image onto the recording sheet; a branching device to switch between an ejection path to eject the recording sheet fed downstream of the fixing device, to outside the apparatus, and a reversing path for duplex printing; and a back curl correction structure disposed in a sheet feeding path between the fixing device and the branching device. The back curl correction structure includes a drive roller; a driven roller; an auxiliary nip portion; a guide member; and a guide moving device to move the guide member to a first position and a second position depending on the condition of the recording sheet.