Image Forming Apparatus Region-Based Fixing Temperature Control
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Solution Overview
Problem
Existing image forming apparatuses face challenges in determining the optimum fixing temperature control value, especially when the laser spot does not move at a constant velocity on the photosensitive member, leading to non-uniform toner layering and varying fixability across the image, making it difficult to handle different image types and positions.
Innovation Solution
The apparatus includes a scanning unit that adjusts scanning velocity based on position and a control unit that analyzes image data to divide the scanning area into regions, determining the fixing temperature based on position and printing ratio for each region, allowing for precise temperature control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a scanning lens with fθ characteristic is used to make the light beam spot move at constant velocity, then image uniformity is improved, but the device size increases
Solution Approach 1:
The patent removes the scanning lens from the optical system entirely, replacing it with a polygon mirror that directly scans the laser beam across the photosensitive member. This extraction of the scanning lens eliminates the need for large optical components while achieving acceptable image formation, directly resolving the contradiction between image uniformity and device size.
Solution Approach 2:
The patent changes the scanning velocity parameter dynamically across different positions of the photosensitive member. By making the spot velocity non-uniform (faster at edges, slower at center) and compensating through variable clock frequency and exposure amount adjustments, the system achieves uniform image density without requiring a scanning lens with fθ characteristic.
2Volume of moving object
If the spot velocity is made non-uniform to reduce device size, then device size is reduced, but toner layering uniformity deteriorates
Solution Approach 1:
The patent applies different exposure parameters to different regions of the photosensitive member. By dividing the scanning area into multiple regions and adjusting the exposure amount and clock frequency locally for each region, the system compensates for the non-uniform spot velocity, ensuring uniform toner layering across the entire image area despite the varying scan speed.
Solution Approach 2:
The patent implements a control mechanism that adjusts the clock frequency and exposure amount based on the position of the light beam spot. This feedback control ensures that even though the spot velocity varies across the scanning area, the resulting toner layering remains uniform by dynamically compensating for velocity differences.
3Device complexity
If a single fixing temperature control value is used for the entire image, then device complexity is reduced, but fixability uniformity deteriorates
Solution Approach 1:
The patent divides the image area into multiple regions along the main scanning direction, with each region assigned a different fixing temperature control value. This segmentation allows the system to address the varying fixability requirements of different image positions (center vs. edges) while maintaining relatively simple temperature control logic for each individual region.
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 enables the determination of an optimum fixing temperature for each region, ensuring uniform image formation and reducing power consumption while maintaining fixability, even for images with varying fixability like text and solid patches.
Implementation Method 1
a scanning unit that scans a surface of a photosensitive member with light and forms a latent image in accordance with image data
Implementation Method 2
a fixing unit that heats and fixes the toner image transferred to a recording material
Data Source
AI summary
An image forming apparatus is used, which includes: a scanning unit that scans a surface of a photosensitive member with light and forms a latent image according to image data; a developing unit that supplies toner to the latent image to develop the latent image; a fixing unit that heats and fixes the toner image on a recording material; and a control unit that controls a fixing temperature based on the image data, wherein the control unit analyzes a printing ratio by dividing the image data into a plurality of regions in a main scanning direction when the scanning unit scans the surface of the photosensitive member with light, and determines the fixing temperature on the basis of the position in the main scanning direction and the printing ratio for each of the plurality of regions.