Image Reading Device Moving Reference Body Shading Correction
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Solution Overview
Problem
Existing image reading devices face challenges in maintaining consistent image quality due to changes in light emission and sensitivity over time, and they cannot adjust the position of reference sheets accurately with respect to the image reading mechanism, leading to suboptimal shading correction.
Innovation Solution
An image reading device with a moving body and a separate reference body that intersects the sheet conveying direction, allowing the recording medium and reference body to contact and separate from the image reading body for precise shading correction, and a method involving the movement of these components to optimize the reading position and distance for accurate image reading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a white reference sheet is placed in contact with the exposure glass for shading correction, then shading correction can be performed, but the distance between the reference sheet and the contact image sensor cannot be adjusted, leading to suboptimal reading quality due to focal length mismatches
Solution Approach 1:
The reference sheet is made movable relative to the exposure glass through a moving body mechanism. The moving body can shift the reference sheet in the sheet conveying direction to an intermediate position during the reading process, allowing dynamic adjustment of the reading position while maintaining contact for shading correction. This resolves the contradiction by enabling both accurate shading correction and adjustable reading position.
2Measurement precision
If the contact image sensor is designed with a fixed focal length on the exposure glass surface, then optimal image reading can be achieved at that specific distance, but component tolerances and assembly tolerances cause the exposure glass surface to not constantly meet the focal length requirement
Solution Approach 1:
The moving body mechanism allows dynamic adjustment of the reference sheet position during the reading process. By shifting the reference sheet to an intermediate position in the sheet conveying direction, the system can compensate for focal length mismatches caused by tolerances, ensuring consistent image reading quality despite variations in exposure glass positioning.
3Ease of operation
If the reference sheet is moved with rotation of the rear roller from standby position to reading position, then the reference sheet can be positioned for shading correction, but the position of the reference sheet with respect to the contact image sensor cannot be adjusted
Solution Approach 1:
The moving body mechanism enables dynamic positioning of the reference sheet during the reading process. After the reference sheet is initially positioned by rear roller rotation, the moving body can further adjust it to an intermediate position in the sheet conveying direction, combining the ease of initial positioning with the precision of adjusted reading position.
Data Source
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AI summary
An image forming apparatus (1), which is used to perform a method of reading images, includes an image reading device (120) and an image forming device (4) to form an image on a recording medium (P). The image reading device (120) includes an image reading body (36) configured to read one of a recording medium (P) and the recording medium (P) together with a background area adjacent to the recording medium (P), a moving body (123) disposed facing the image reading body (36), and a reference body (100) as a reference in shading correction. The moving body (123) is configured to hold the recording medium (P) and the reference body (100) in a direction intersecting a sheet conveying direction of the recording medium (P) such that the recording medium (P) and the reference body (100) contact to and separate from the image reading body (36).