Fixing Device Air Ejection and Suction for Sheet Undulation
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Solution Overview
Problem
In image forming apparatuses, the separation of recording sheets from fixing members after toner fixation is challenging due to increased toner adhesion and air swirling currents, leading to sheet undulation and potential image defects, especially with thin papers and coated papers.
Innovation Solution
A fixing device with an air ejection section to blow air and separate the recording sheet, accompanied by guide members and an air suction section to manage air flow and prevent sheet undulation, ensuring smooth discharge without image defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If air is blown against the nip portion to separate recording sheets, then separation performance is improved, but air swirling currents are generated causing sheet undulation and image defects
Solution Approach 1:
The air blowing function is divided into multiple air ejection sections positioned at different locations (exit side and upstream of nip portion) with different ejection directions. This segmentation allows the air flow to be controlled more precisely, achieving effective separation while minimizing harmful swirling currents that cause sheet undulation.
Solution Approach 2:
Different air ejection sections are configured with specific ejection directions tailored to their local positions. The air ejection section at the exit side blows in the sheet discharge direction, while the upstream section blows in a direction that prevents sheet adhesion without creating excessive turbulence. This localized optimization resolves the contradiction between separation effectiveness and sheet stability.
2Productivity
If air ejection volume is increased for faster printing speeds, then productivity is improved, but sheet undulation and image defects increase
Solution Approach 1:
The air ejection system is segmented into multiple sections that can operate at different air volumes and pressures. This allows the total air ejection volume to be increased for high-speed printing while distributing the air flow across different zones, preventing excessive localized air pressure that would cause sheet undulation and image defects.
Solution Approach 2:
Different air ejection sections are optimized for different functions: some sections prioritize separation effectiveness with higher air volume, while others focus on preventing sheet adhesion with more controlled air flow. This local optimization enables high productivity while maintaining image quality by preventing sheet undulation in critical areas.
3Reliability
If separation claw tip contacts the fixing roller surface, then separation performance is improved, but scratches occur on the fluorine resin surface layer
Solution Approach 1:
The separation function is extracted from the separation claw mechanical contact method and transferred to air ejection sections. By using air flow to achieve separation, the need for mechanical contact between the separation claw tip and the fluorine resin surface layer is eliminated, preventing scratches while maintaining effective separation performance.
Solution Approach 2:
Air flow is introduced as an intermediary medium to achieve sheet separation without direct mechanical contact. The air ejection sections create a cushion of air between the separation claw and the fixing roller surface, allowing the separation function to be performed without damaging the fluorine resin surface layer.
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 separates recording sheets from the fixing device without causing undulation or image defects, even at increased air volumes for faster printing speeds and with thin papers, maintaining image quality.
Implementation Method 1
an air ejection section to eject and blow air against the recording medium to separate the recording medium from the fixing member
Implementation Method 2
an air suction section provided on a opposite side position with respect to the first guide member in the second guide member to suction air of the clearance and attract the recording medium to the second guide member
Data Source
AI summary
A fixing device to fix a toner image on a recording medium in a nip portion formed by a heated fixing member and a pressure member, the fixing device including: an air ejection section to eject and blow air against the recording medium to separate the recording medium from the fixing member, a first guide member provided on a fixing face side of the recording medium discharged from the nip portion to guide the recording medium, a second guide member provided on a non-fixing face side of the recording medium discharged from the nip portion to guide the recording medium, also having a predetermined clearance with respect to the pressure member, and an air suction section provided on a opposite side position with respect to the first guide member in the second guide member to suction air of the clearance and attract the recording medium to the second guide member.