Image Reading Apparatus Cover Gap Light Interference Correction
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Solution Overview
Problem
Existing image reading apparatuses face challenges in accurately detecting document sheet sizes due to external light interference from gaps between the cover and the document sheet table, which affects detection accuracy.
Innovation Solution
The apparatus includes a photoelectric conversion portion disposed outside the maximum readable size area, covered by the cover member, which outputs data used to correct image data read when the cover member's pivoting angle changes, allowing for improved detection accuracy by adjusting the threshold values based on external light conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cover member is closed to perform image reading, then the reading process can be executed, but external light enters through gaps between the cover and document sheet table, degrading detection accuracy
Solution Approach 1:
The patent performs image reading at a specific moment when the cover member's pivoting angle changes from exceeding a detection angle to being equal to or less than the detection angle. This preliminary action captures the document image before the cover is fully closed and external light can significantly interfere, thereby maintaining detection accuracy while enabling the reading process
Solution Approach 2:
The patent uses a photoelectric conversion portion to detect external light conditions and provides feedback to a data correcting portion. This feedback mechanism allows the system to correct image data based on detected external light levels, compensating for light interference and maintaining reliable detection accuracy
2Productivity
If image reading is performed immediately before cover closure, then reading speed is improved, but external light interference from gaps reduces measurement precision
Solution Approach 1:
The system performs the image reading operation at the optimal moment when the cover angle changes to the detection threshold, which is immediately before full closure. This timing achieves both fast reading speed and acceptable external light conditions, resolving the contradiction between productivity and precision
Solution Approach 2:
The patent changes the parameter of reading timing based on the cover member's pivoting angle. By dynamically adjusting when the reading occurs based on the angle parameter, the system optimizes both the speed of reading and the precision of measurement by selecting the moment when external light interference is minimized
3Measurement precision
If the photoelectric conversion portion is placed outside the maximum readable size area, then external light can be detected for correction, but the area is covered by the cover member during normal operation
Solution Approach 1:
The patent divides the photoelectric conversion function into two separate portions: one for normal image reading within the maximum readable size area, and another for external light detection outside that area. This segmentation allows each portion to perform its specific function optimally without interference, achieving both measurement precision and operational simplicity
Solution Approach 2:
The photoelectric conversion portion disposed outside the readable area acts as an intermediary that detects external light conditions without interfering with the main image reading process. It serves as a mediator that provides environmental light information for correction purposes while remaining spatially separated from the primary reading function
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 solution enhances the detection accuracy of document sheet sizes by accounting for external light interference, ensuring precise identification of document sheet boundaries and sizes.
Implementation Method 1
a photoelectric conversion portion disposed in an area that is out of a predetermined maximum readable size area in the image reading portion, and is covered by the cover member when the cover member is closed
Data Source
AI summary
In image reading apparatus, reading control portion causes image reading portion to read at least line of image data when pivoting angle of cover member with respect to document sheet table has changed from angle exceeding predetermined detection angle to angle equal to or less than detection angle. Photoelectric conversion portion is disposed in area that is out of predetermined maximum readable size area in image reading portion, and is covered by cover member when cover member is closed. Data correcting portion corrects image data read by reading control portion, based on output of photoelectric conversion portion output when pivoting angle has changed from angle exceeding detection angle to angle that is equal to or less than detection angle. Document sheet width detecting portion detects width, in main scanning direction, of document sheet placed on document sheet mounting surface, based on image data corrected by data correcting portion.