Image Reading Unit Edge Detection via Positional Shift
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Solution Overview
Problem
Conventional image-reading devices face challenges in accurately determining the arrival of the leading or trailing edge of an original sheet at the read region, especially when there is no identification image on the original-pressing plate, and when the image values obtained from the sheet and the plate are similar.
Innovation Solution
An image reading device with a conveying unit, an image reading unit, an opposing member with distinct parts, and a control device that moves the image reading unit between different read positions to generate unique image values, allowing for reliable edge detection based on changes in scan data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an identification image is depicted on the original-pressing plate to enable edge detection, then the leading or trailing edge of the original sheet can be determined, but the identification image adversely affects the image of the original read by the image-reading unit
Solution Approach 1:
The patent extracts the identification function from the original-pressing plate by removing the identification image entirely. Instead, it uses the inherent structural difference between the original-pressing plate and the original sheet (the presence of a gap when the sheet is loaded) to enable edge detection without adding interfering visual elements to the reading region.
Solution Approach 2:
The patent introduces a gap between the original-pressing plate and the original sheet as an intermediary element. This gap serves as a mediator that allows the image-reading unit to detect the presence and position of the original sheet without requiring any identification images on the pressing plate itself, thereby eliminating image interference while maintaining detection capability.
2Object-generated harmful factors
If no identification image is depicted on the original-pressing plate to avoid image interference, then the original image quality is preserved, but the device cannot reliably determine when the leading or trailing edge of the original sheet has arrived at the read region
Solution Approach 1:
The patent enables the system to detect sheet edges using the natural state of the system components themselves. The original-pressing plate and original sheet create a detectable gap condition that serves its own detection purpose without requiring external identification marks, making the detection mechanism self-sufficient and free from interfering elements.
Solution Approach 2:
Instead of using the presence of an identification image to detect edges, the patent inverts the approach by detecting edges through the absence of contact between the original-pressing plate and the original sheet. The detection is based on the gap condition rather than visual patterns, fundamentally reversing the traditional identification image approach.
3Object-generated harmful factors
If the image values from the original sheet and original-pressing plate are similar to avoid adding complex identification patterns, then the original image quality is maintained, but the device cannot distinguish between the sheet and the plate for accurate edge detection
Solution Approach 1:
The patent performs preliminary detection of the gap between the original-pressing plate and the original sheet before the sheet enters the reading region. By detecting the positional relationship and gap condition in advance, the system can determine edge arrival without needing to differentiate between similar image values during the reading process itself.
Solution Approach 2:
The gap between the original-pressing plate and the original sheet serves as an intermediary detection signal. This physical separation creates a detectable state that allows the control device to distinguish between the plate and sheet conditions without relying on image value differences, thereby maintaining image quality while enabling reliable detection.
Data Source
AI summary
In an image reading device, an opposing member opposes an image reading unit. The opposing member has a first part and a second part. A moving unit moves the image reading unit between first and second read positions. An image value generated by reading an image of the first part at the first read position is different from an image value generated by reading an image of the second part at the second read position. The control device is configured to: set a read position to selected one of the first read position and the second read position; control the moving unit to move the image reading unit to the read position; and determine that an edge of the original sheet reaches the reading region when image values generated by the image reading unit are changed while the conveying unit conveys the original sheet along the conveying path.