Document Scanner Sensor Units Angled Light Guides
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Solution Overview
Problem
Large format document scanners face challenges in manufacturing due to the increased risk of failure in image sensor units with larger detector arrays, leading to higher costs and inconsistencies in scanning motion, which result in errors when stitching together scan line portions.
Innovation Solution
The use of first and second image sensor units with angled light guides and a common light source, arranged in a staggered configuration to reduce the distance between imaging lines and minimize inconsistencies in scanning motion, allowing for a continuous composite imaging line with reduced stitching errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If multiple image sensor units are used to scan large format documents, then the scanning width capability is improved, but the device complexity increases due to the need for stitching multiple scan line portions together
Solution Approach 1:
The document scanning system is divided into multiple independent image sensor units, each responsible for capturing a specific portion of the scan line. This segmentation allows the system to handle large format documents by processing smaller segments independently and then combining them, resolving the contradiction between increased scanning width capability and stitching complexity.
2Ease of manufacture
If contact image sensors are arranged in a physically overlapping relationship to ensure continuous scan lines, then the manufacturing cost is reduced by avoiding bulky optical systems, but the distance between imaging lines increases leading to stitching errors
Solution Approach 1:
The patent introduces angular orientation of light guides in the third dimension (vertical angle) to resolve the horizontal distance issue. By angling the light guides, the imaging lines from adjacent sensors can be brought into closer horizontal alignment without requiring the sensors to be physically closer in the horizontal direction, thus maintaining manufacturing simplicity while improving stitching accuracy.
3Manufacturing precision
If the distance between adjacent scan line portions is minimized, then stitching accuracy is improved, but the device complexity increases due to tighter spacing requirements for detector arrays and circuitry
Solution Approach 1:
The light guides are oriented at angles in the vertical dimension, which allows the imaging lines to be projected closer together in the horizontal scanning direction without requiring the sensor units themselves to be placed closer together. This dimensional transformation resolves the contradiction by achieving horizontal proximity while maintaining adequate vertical separation for circuitry.
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 configuration reduces the risk of stitching errors and allows for wider document scanning while maintaining a compact and cost-effective design, ensuring accurate and continuous image capture.
Implementation Method 1
one or more light guides for directing light from a respective one of two imaging lines onto the detectors
Implementation Method 2
one or more light guides for directing light from a respective one of two imaging lines onto the detectors
Data Source
AI summary
A document scanner comprises a first image sensor unit (32) and a second image sensor unit (30) and a scanning mechanism (70, 72, 76, 80) for causing relative movement between a document and the units so that the units scan the document in a scanning direction. The first unit (32) is situated ahead of the second unit (30) in the scanning direction and partially overlaps the second unit. Each sensor unit has a respective linear array (44) of electromagnetic radiation detectors and one or more light guides (48, 49) for directing light from a respective one of two imaging lines (63) on to the detectors, wherein, in use, the imaging lines scan the document to capture data representative of two respective sets of scan line portions for combination to obtain a succession of scan lines for the document, the one or more light guides of the first unit (32) are angled rearwardly with respect to the scanning direction, whilst the one or more light guides of the second unit (30) are angled forwardly with respect to the scanning direction, so as to reduce the distance with respect to the scanning direction, between the imaging lines (63).