Bidirectional Image Sensor Reference Position Detection
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Solution Overview
Problem
Image reading apparatuses that support both flatbed and automatic document feeder (ADF) methods suffer from reduced reading precision due to backlash issues, as the reference position is detected in only one direction, affecting the start and read positions.
Innovation Solution
The image reading apparatus incorporates a drive mechanism that allows the image sensor to move in two directions, with a reference plate used to detect reference positions in both directions, enabling precise document reading by adjusting the sensor's movement accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the reference position is detected in only one direction (scanning or return), then the device complexity is reduced, but the reading precision deteriorates due to backlash affecting start and read positions
Solution Approach 1:
The patent segments the reference position detection into two separate detections: one for the scanning direction and another for the return direction. This allows each direction to have its own optimized reference position, eliminating the negative impact of backlash on reading precision while maintaining manageable system complexity.
2Measurement precision
If the image sensor moves in two directions to detect reference positions, then the reading precision is improved, but the device complexity increases due to bidirectional drive mechanism
Solution Approach 1:
The patent implements dynamic reference position detection by detecting reference positions differently based on the movement direction of the image sensor. The system adaptively selects and uses appropriate reference positions (first reference position for scanning direction, second reference position for return direction) to maintain high reading precision throughout the bidirectional movement cycle.
3Ease of operation
If backlash is not compensated through bidirectional reference detection, then the ease of operation is maintained, but the reading precision deteriorates at start and read positions
Solution Approach 1:
The patent creates a virtual copy of the reference position detection process by detecting reference positions in both scanning and return directions. This virtual duplication allows the system to compensate for backlash effects without adding physical complexity, maintaining operational simplicity while achieving high reading precision through computational use of multiple reference positions.
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 improves reading precision by allowing the image sensor to accurately detect and adjust for backlash, ensuring high-quality image capture in both flatbed and ADF reading methods.
Implementation Method 1
an image sensor in which a light receiving element is arranged in a predetermined direction for reading a document
Data Source
AI summary
An image reading apparatus, includes an image sensor, a drive mechanism configured to cause the image sensor to move in a first direction and a second direction opposite to the first direction, a reference plate, and a control unit configured to execute a first reading method of detecting a first reference position by driving the image sensor in the first direction and reading the reference plate, thereafter reading a document by driving the image sensor in the first direction, and a second reading method of detecting a second reference position by driving the image sensor in the second direction and reading the reference plate, and thereafter reading a document by driving the image sensor in the second direction.