Fixation Roller Speed Control via Optical Feedback
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Solution Overview
Problem
Existing image formation apparatuses face challenges in accurately sensing the speed of conveyance of moving elements, particularly when the fixation roller is eccentric or the sheet flutters, leading to misalignment and quality issues in printing due to inaccuracies in speed detection.
Innovation Solution
An image formation apparatus that generates multiple images of the moving element at different timings and senses the distance between the generator and the element at each shot, using a hardware processor to calculate and adjust the conveyance speed based on these images and distances, thereby correcting for errors caused by eccentricity or fluttering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the fixation roller is controlled to be higher in speed of conveyance than the secondary transfer portion to apply tensile force to the sheet, then wrinkles are prevented in the sheet, but misalignment in transfer occurs due to thermal expansion of the fixation roller
Solution Approach 1:
The patent implements a feedback control system where the actual speed of the fixation roller is continuously detected and compared with the target speed. The detected speed information is fed back to the control unit, which adjusts the roller speed to maintain the desired speed difference with the secondary transfer portion, compensating for thermal expansion effects and preventing misalignment.
Solution Approach 2:
The patent replaces mechanical speed detection methods with an optical measurement system. A light source and photodetector are used to non-contactively measure the speed of the fixation roller by detecting the frequency of light modulation caused by the rotating roller surface, providing more accurate and stable speed detection.
2Ease of operation
If the speed detection apparatus calculates speed based on images obtained at constant intervals, then speed can be measured, but accuracy deteriorates when the sheet flutters during conveyance
Solution Approach 1:
The patent replaces image-based speed detection with direct optical measurement of the fixation roller's rotation speed. By using a light source and photodetector to measure the frequency of light modulation caused by the rotating roller, the system obtains accurate speed data without being affected by sheet flutter or image magnification changes.
Solution Approach 2:
The patent introduces the fixation roller itself as an intermediary for speed detection. Instead of detecting the speed of the fluttering sheet directly, the system measures the rotation speed of the fixation roller, which serves as a stable reference that indirectly provides the conveyance speed information needed for control.
3Measurement precision
If multiple images are taken to calculate speed, then speed information can be obtained, but device complexity increases due to additional sensors and processing
Solution Approach 1:
The patent extracts the speed detection function from the image formation system. Instead of using the imaging system to detect sheet speed, a separate, dedicated optical measurement system is employed to measure the fixation roller's rotation speed, simplifying the overall system architecture and reducing processing complexity.
Solution Approach 2:
The patent uses the fixation roller as an intermediary element that enables simple speed detection. By measuring the rotation speed of this intermediary component rather than directly measuring the sheet speed, the system achieves accurate conveyance speed measurement with minimal device complexity.
Data Source
AI summary
An image formation apparatus includes a conveyor configured to convey a moving element on which an image is formed, a generator configured to generate a first image and a second image by shooting the conveyed moving element at different timing, a detector configured to sense a first distance between the generator and the moving element at the time of shooting of the first image and sense a second distance between the generator and the moving element at the time of shooting of the second image, and a hardware processor configured to calculate a speed of conveyance of the moving element based on the first image, the second image, the first distance, and the second distance, and output the speed of conveyance.