Image Forming Apparatus Cooling Sheet After Erasing Erasable Ink
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Solution Overview
Problem
Image forming apparatuses face challenges in applying image formation processing using erasable ink immediately after erasing an image with a fixing device, as the high temperature of the sheet causes the ink to be erased, preventing normal image formation.
Innovation Solution
The apparatus includes a first image forming unit for fixing images with a colorant, a second image forming unit for using erasable ink, and a fixing device that heats and erases the ink, with a processing control unit ensuring the sheet cools sufficiently before reaching the second image forming unit for re-imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If image formation processing using erasable ink is applied immediately after erasing with the fixing device, then productivity is improved by continuous processing, but the erasable ink is erased by the high temperature of the sheet and image formation cannot be normally performed
Solution Approach 1:
The patent introduces a cooling conveyance process that occurs before the second image forming unit applies erasable ink. The sheet conveying unit transports the sheet from the fixing device to the second image forming unit while allowing it to cool down to a temperature that will not erase the erasable ink. This preliminary cooling action ensures that when the erasable ink is subsequently applied, it remains on the sheet and image formation can proceed normally, thus resolving the contradiction between continuous processing and image quality.
2Productivity
If the sheet is conveyed quickly from the fixing device to the second image forming unit, then productivity is improved, but the sheet temperature remains high and erases the erasable ink
Solution Approach 1:
The patent dynamically adjusts the sheet conveyance speed based on temperature requirements. The sheet conveying unit is controlled to transport the sheet at a speed that allows sufficient cooling time while still maintaining continuous processing. This dynamic control of conveyance speed enables the sheet to cool down to an appropriate temperature before reaching the second image forming unit, preventing erasure of the erasable ink while maintaining productivity.
3Device complexity
If the fixing device is used for both toner fixing and erasable ink erasing, then device complexity is reduced and cost is saved, but the high temperature required for erasing affects subsequent erasable ink application
Solution Approach 1:
The patent introduces the sheet conveying unit as an intermediary between the fixing device and the second image forming unit. This intermediary component provides a transition zone where the sheet can cool down after being heated by the fixing device for erasing. The conveying unit acts as a buffer that separates the high-temperature erasing process from the low-temperature ink application process, thereby eliminating thermal interference while maintaining device simplicity.
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 configuration allows for successful application of image formation processing using erasable ink on sheets that have been erased by the fixing device, ensuring the ink is not prematurely erased, thus enabling normal image formation.
Implementation Method 1
executing erasing processing for heating the sheet, on which the image is formed with the second colorant, to the predetermined erasing temperature to thereby erase the second colorant on the sheet
Implementation Method 2
executing fixing processing for nipping and conveying the sheet, on which the image is formed by the first image forming unit, while heating the sheet to thereby fix the image on the sheet
Implementation Method 3
required time that elapses until the sheet reaches the second image forming unit from the fixing device is equal to or longer than predetermined cooling time
Data Source
AI summary
An image forming apparatus includes: a first image forming unit configured to form an image on a sheet using a first colorant to be heat-fixed on the sheet; a second image forming unit configured to form an image on the sheet using a second colorant that is erasable by heating; and a fixing device arranged further on a downstream side in a sheet conveying direction than the first image forming unit and further on an upstream side in the sheet conveying direction than the second image forming unit and capable of executing fixing processing for heat-fixing the image, which is formed on the sheet by the first image forming unit, on the sheet and executing erasing processing for heating the sheet, on which the image is formed with the second colorant, to erasing temperature to thereby erase the second colorant on the sheet.