Paper Pre-heater Front Surface Heating for Offset Reduction
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Solution Overview
Problem
Existing image formation apparatuses face issues with fixing under offset, image unevenness, and disturbance of unfixed toner images due to inadequate heating of thick or tack papers, which can lead to toner blister or paper blister.
Innovation Solution
The image formation apparatus includes a paper pre-heater that heats the front surface of the paper on the upstream side of the intermediate transfer unit, ensuring sufficient temperature rise on the front surface without forming a paper nip, thus reducing the risk of image formation failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the paper pre-heating member is disposed between the transferrer and the fixer and heated from the back surface of the paper, then the paper temperature can be raised, but for thick paper or tack paper the heat cannot be sufficiently transmitted to the front surface, resulting in fixing under offset
Solution Approach 1:
Instead of heating the paper from the back surface (release paper side) as in conventional designs, the patent heats the paper from the front surface (image formation surface side) by disposing the paper pre-heating member on the upstream side of the transferrer. This inversion of heating direction allows heat to be effectively transmitted to the front surface of thick paper and tack paper, ensuring sufficient temperature for proper fixing without causing fixing under offset.
Solution Approach 2:
The paper pre-heating member is disposed on the upstream side of the transferrer to perform preliminary heating of the paper before the toner image is transferred. This preliminary action ensures that the paper reaches the necessary temperature for proper fixing before the toner is applied, preventing fixing under offset while avoiding excessive heating that would cause toner blister or image unevenness.
2Temperature
If the amount of heating from the back-surface side of the paper is increased to such an extent that fixing under offset does not occur, then the paper temperature rises sufficiently, but moisture contained in the paper is vaporized and air bubbles are generated in the toner layer, resulting in image unevenness and toner blister
Solution Approach 1:
By inverting the heating direction to heat from the front surface rather than the back surface, the patent achieves sufficient paper temperature without excessive heat accumulation. The front-surface heating allows controlled temperature rise that prevents moisture vaporization and air bubble formation in the toner layer, eliminating image unevenness and toner blister while ensuring proper fixing temperature is reached.
Solution Approach 2:
The paper pre-heating member is designed to heat only the local area where the paper passes through on the upstream side of the transferrer, rather than heating the entire paper sheet uniformly from the back surface. This localized heating approach prevents excessive temperature rise that would cause moisture vaporization, while still achieving sufficient temperature for proper fixing at the critical transfer zone.
3Temperature
If the paper pre-heating member is brought into contact with the paper to heat it, then the paper temperature can be raised, but disturbance of the unfixed toner image occurs and toner is scattered
Solution Approach 1:
The paper pre-heating member heats the paper in advance on the upstream side of the transferrer, before the toner image is transferred onto the paper. This timing ensures that the paper is warmed up without the toner present, eliminating the risk of toner disturbance or scattering. The heating action is completed prior to toner application, maintaining image quality while achieving necessary paper temperature for proper fixing.
4Temperature
If a paper pre-heating member is disposed between the transferrer and the fixer, then the paper can be heated, but the structure becomes more complex and the device size increases
Solution Approach 1:
The paper pre-heating member is integrated into the existing image formation apparatus structure, serving multiple functions: it heats the paper on the upstream side of the transferrer, works in conjunction with the transferrer and fixer, and can be controlled through the existing control unit. This multi-functional integration achieves effective paper heating without significantly increasing device complexity or requiring separate dedicated heating systems.
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 effectively reduces the occurrence of fixing under offset and image unevenness, while minimizing the chance of toner or paper blister, and prevents disturbance of unfixed toner images.
Implementation Method 1
a paper pre-heater that heats, on the upstream side of the transferrer in the paper conveyance direction, the image formation surface of the paper
Data Source
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AI summary
Provided is an image formation apparatus (1) capable of reducing occurrence of image formation failure. An image formation apparatus (1) includes a transferrer (42) that forms a toner image on an image formation surface of paper, a fixer (60) that fixes the toner image on the paper, a paper conveyor (50) that conveys the paper between an upstream side of the transferrer (42) and a downstream side of the fixer (60) in a paper conveyance direction, and a paper pre-heater (80) that heats, on the upstream side of the transferrer (42) in the paper conveyance direction, the image formation surface of the paper.