Image Defect Detection in Image Forming Apparatus
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Solution Overview
Problem
Image forming apparatuses face challenges in accurately detecting image defects due to variations in sheet conveyance speed during image formation, which can lead to erroneous defect determination during image reading.
Innovation Solution
An image forming apparatus with a control unit that adjusts the conveyance speed of the sheet and a determination unit that excludes image data from periods of speed variation, allowing for accurate image defect detection by reading images only during stable conveyance speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the conveyance speed of the sheet is kept constant during image reading, then the image can be stably read, but the conveyance speed must be maintained constant even during image formation which causes timing issues
Solution Approach 1:
The patent segments the image data into multiple pieces corresponding to different conveyance speed periods. The determination unit processes each piece separately, excluding pieces obtained during speed variation periods and using only those from stable conveyance periods for defect determination. This segmentation allows the system to maintain constant speed during reading while allowing speed variations during formation.
Solution Approach 2:
The patent performs preliminary identification of conveyance speed variation periods before defect determination. The determination unit pre-identifies which time periods correspond to speed variations and excludes image data from these periods beforehand, ensuring that only data from stable conveyance periods is used for defect detection.
2Productivity
If the conveyance speed varies during image formation to improve productivity, then image formation efficiency increases, but image reading accuracy deteriorates due to speed variation influence
Solution Approach 1:
The patent extracts and excludes image data obtained during conveyance speed variation periods from the defect determination process. The determination unit identifies and removes data pieces corresponding to speed variation periods, using only data from stable conveyance periods for accurate defect detection, thus separating the harmful speed variation influence from the measurement process.
Solution Approach 2:
The system performs preliminary identification of speed variation periods and pre-excludes data from these periods before defect determination. This preliminary action ensures that only image data obtained during stable conveyance periods is used for defect detection, maintaining measurement precision while allowing productivity improvements.
3Adaptability or versatility
If image data from all conveyance periods is used for defect determination, then the detection process is comprehensive, but erroneous defect determination occurs due to speed variation influence
Solution Approach 1:
The patent applies different quality standards to different portions of image data. The determination unit evaluates each image data piece individually, determining whether it was obtained during a stable conveyance period or a speed variation period. Only data pieces from stable periods are used for defect determination, applying local quality assessment to ensure accuracy.
Solution Approach 2:
The patent segments the complete image data into multiple pieces corresponding to different conveyance speed conditions. The determination unit processes each segment separately, excluding segments from speed variation periods and using only segments from stable periods for defect determination, maintaining both comprehensiveness and accuracy.
Data Source
AI summary
An image forming apparatus includes an image forming unit configured to form an image on a sheet; a reading unit configured to read the image formed on the sheet by the image forming unit during a period in which the sheet is being conveyed by a conveying unit; a control unit configured to control a conveyance speed of the sheet by the conveying unit; and a determination unit configured to determine whether or not there is an image defect in the image formed on the sheet by the image forming unit based on image data of a first partial image read by the reading unit, excluding a second partial image passing through the reading unit during a speed variation period in which the control unit varies the conveyance speed of the sheet.