Dynamic Pressure Fixing for Low-Gloss Toner Images
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Solution Overview
Problem
Existing image forming apparatuses face challenges in controlling the gloss of printed images, particularly in achieving low-gloss outputs while minimizing defective fixing and offset issues, especially when using toners with particle sizes larger than 6 μm.
Innovation Solution
The apparatus employs a fixing device with a pressing member that applies varying pressures and heating times depending on the mode of operation, with a lower pressure and longer heating time in the low-gloss mode to reduce gloss and prevent offset, using toners with a volume-mean particle size of 6 μm or smaller.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If high pressure is applied to the toner image in the pressing portion, then the gloss of the formed image is increased, but the toner image may offset or fail to fix properly
Solution Approach 1:
The pressing member dynamically adjusts the pressure applied to the toner image between two distinct states: a first pressure for high-gloss images and a second lower pressure for low-gloss images. This dynamic pressure adjustment allows the system to optimize both gloss control and fixability reliability by selecting appropriate pressure levels based on the desired image output characteristics.
Solution Approach 2:
The invention changes the pressure parameter applied by the pressing member to the toner image. By switching between a first pressure (higher) and a second pressure (lower), the system controls the gloss of the formed image while maintaining reliable fixing. The pressure parameter is adjusted according to the type of image to be formed, enabling flexible control over image properties without compromising fixability.
2Productivity
If the recording material passes through the pressing portion quickly, then productivity is improved, but the toner image may not fix properly
Solution Approach 1:
The system dynamically adjusts the passing time of the recording material through the pressing portion based on the image type. For low-gloss images, the material passes through more slowly, allowing adequate time for proper fixing at lower pressure. For high-gloss images, the material can pass through more quickly with higher pressure applied. This dynamic timing adjustment maintains both productivity and fixability reliability.
Solution Approach 2:
The invention implements periodic adjustment of the pressing conditions and passing time based on the type of image being formed. The system alternates between different operating modes (first pressure with shorter passing time for high-gloss, second lower pressure with longer passing time for low-gloss), enabling flexible control over both productivity and fixing reliability according to production requirements.
3Illumination intensity
If low pressure is applied to achieve low-gloss output, then gloss control is improved, but defective fixing may occur
Solution Approach 1:
The invention changes the pressure parameter to a second lower pressure when low-gloss output is desired. This pressure reduction achieves the desired gloss control while the system compensates by adjusting the passing time to ensure adequate fixing duration, thereby maintaining fixability reliability even at lower pressure levels.
Solution Approach 2:
The system periodically switches between different pressure levels and corresponding passing times based on the desired image gloss. When low-gloss output is required, the system applies the second lower pressure with an extended passing time, ensuring that proper fixing is achieved despite the reduced pressure, thus preventing defective fixing while achieving the desired gloss control.
4Device complexity
If the pressing member uses a single pressure level, then device complexity is reduced, but gloss control versatility is limited
Solution Approach 1:
The pressing member is designed with dynamic capability to switch between two pressure levels (first pressure and second pressure) rather than using a single fixed pressure. This dynamic design provides versatile gloss control for different image types while maintaining relatively simple device architecture. The ability to adjust between pressure states enables the system to produce both high-gloss and low-gloss images without requiring complex multi-component pressing mechanisms.
Solution Approach 2:
The pressing member is designed with multi-functionality, capable of performing both high-pressure pressing for high-gloss images and low-pressure pressing for low-gloss images. This universal design allows a single pressing mechanism to handle multiple image types and gloss requirements, eliminating the need for separate pressing devices for different gloss levels and thereby maintaining device simplicity while achieving gloss control versatility.
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 approach effectively achieves images with lower gloss in the low-gloss mode while minimizing defective fixing and offset, even with smaller toner particle sizes, and maintains high fixability.
Implementation Method 1
a heating member that heats the fixing member
Implementation Method 2
a pressing member that applies pressure to the toner image at a pressing portion
Data Source
AI summary
An image forming apparatus includes a toner-image-forming device that forms a toner image on a recording material with a toner having a volume-mean particle size of about 6 μm or smaller; and a fixing device that includes a fixing member that fixes the toner image, a pressing member that applies pressure to the toner image, and a heating member that heats the fixing member. The pressing member applies a first pressure to the toner image while the recording material carrying the toner image passes through a pressing portion by taking a first passing time period in a first state. The pressing member applies a second pressure lower than the first pressure to the toner image while the recording material carrying the toner image passes through the pressing portion by taking a second passing time period longer than the first passing time period in a second state.