Document Sheet Tilt Correction in Image Reading Apparatus
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Solution Overview
Problem
Conventional image reading apparatuses face challenges in confirming the correction of document sheet tilt, leading to potential insufficient tilt correction and inconsistent document sheet conveyance.
Innovation Solution
The apparatus employs two document sheet sensors and independent roller pairs to detect and adjust the tilt of the document sheet by changing the rotation speed ratio of the roller pairs, ensuring the document sheet is conveyed without tilt by the time it reaches the reading position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the rotation speeds of the two sets of independent roller pairs are changed to correct tilt, then the tilt correction capability is improved, but the conveyance stability deteriorates
Solution Approach 1:
The system performs preliminary detection of document sheet tilt using two document sheet sensors positioned upstream before the reading position. Based on the detection results, the control portion pre-adjusts the rotation speed ratio of the two sets of independent roller pairs to correct the tilt before the document sheet reaches the reading position, ensuring both tilt correction precision and conveyance stability.
Solution Approach 2:
The system dynamically adjusts the rotation speeds of the two sets of independent roller pairs based on real-time tilt detection. The control portion continuously monitors the document sheet position and modifies the speed ratio between the left and right roller pairs to actively correct tilt while maintaining stable conveyance through coordinated rotation control.
2Measurement precision
If two document sheet sensors are used to detect tilt, then the measurement precision is improved, but the device complexity increases
Solution Approach 1:
The system divides the tilt detection function into two separate document sheet sensors positioned at different locations upstream. Each sensor independently detects the document sheet position at its specific location, and the control portion processes these segmented detection results to calculate and correct the tilt angle, achieving high measurement precision through distributed sensing.
3Manufacturing precision
If the detection position is upstream of the reading position, then the time for tilt correction is increased, but the correction effectiveness is improved
Solution Approach 1:
The document sheet sensors are positioned upstream of the reading position to enable preliminary tilt detection and correction. The control portion uses the detection results to adjust the roller pair rotation speeds in advance, ensuring that tilt correction is performed during the conveyance time before the document sheet reaches the reading position, thereby maximizing correction effectiveness without excessive time loss.
Data Source
AI summary
An image sensor reads an image from a document sheet at a reading position. Two document sheet sensors are capable of detecting the document sheet at two positions along boundaries of a reference pass-through area of the document sheet at a detection position more on an upstream side of a conveying direction than the reading position. Two sets of independent roller pairs are arranged with an interval provided therebetween in a width direction at positions between the detection position and the reading position, and rotation speeds thereof can be changed independently. A control portion changes, when the document sheet is detected by one of the two document sheet sensors, a speed ratio of the two sets of independent roller pairs from a reference ratio to a correction ratio during an adjustment period that lasts until the document sheet is no longer detected by both of the two document sheet sensors.