Code Reader Scheimpflug Optical System Depth-of-Field Evaluation
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Solution Overview
Problem
In distribution sites where workpieces are conveyed closely together, it is challenging to accurately determine which workpiece a code read by a code reader should be assigned to, leading to potential code misassignment.
Innovation Solution
A code reader equipped with a Scheimpflug optical system and a control unit that calculates an index to evaluate whether a decoded code is within the depth-of-field region, allowing for accurate assignment of codes to the correct workpieces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If workpieces are conveyed closely together to increase productivity, then the productivity is improved, but the accuracy of code assignment to workpieces deteriorates
Solution Approach 1:
The patent introduces a depth dimension by creating a depth-of-field region perpendicular to the conveying direction. The imaging unit is configured to image only workpieces within this specific depth range, adding a spatial filtering dimension that distinguishes between closely spaced workpieces in the conveying direction, thereby enabling accurate code assignment even at high conveying speeds.
Solution Approach 2:
The patent applies local quality by creating a localized depth-of-field region that selectively images only the target workpiece while excluding adjacent workpieces. This localized imaging approach ensures that only codes from workpieces within the specific depth range are captured, improving code assignment accuracy without reducing productivity.
2Device complexity
If a conventional imaging system is used to read codes, then the device complexity is reduced, but the ability to distinguish codes from adjacent workpieces deteriorates
Solution Approach 1:
The patent employs a Scheimpflug optical system that creates a tilted depth-of-field region perpendicular to the conveying direction. This dimensional approach allows the imaging unit to selectively capture codes from target workpieces while excluding codes from adjacent workpieces, significantly improving code reading accuracy without requiring complex additional hardware.
Solution Approach 2:
The patent changes the imaging parameters by configuring the imaging unit with specific optical characteristics (Scheimpflug condition) that create a depth-of-field region at a predetermined angle. This parameter change enables the system to distinguish between workpieces based on their depth position, improving reliability while maintaining relatively simple device complexity.
3Ease of operation
If the depth of field is increased to capture codes from multiple workpieces, then the ease of operation is improved, but the code misassignment risk increases
Solution Approach 1:
The patent applies local quality by creating a localized depth-of-field region that images only workpieces within a specific depth range perpendicular to the conveying direction. This localized approach maintains ease of operation for target workpieces while preventing code misassignment by excluding workpieces outside the designated depth region from being imaged.
Solution Approach 2:
The patent segments the imaging space into distinct depth regions, with the depth-of-field region selectively capturing only the target workpiece. This segmentation approach allows the system to maintain comprehensive code reading coverage for the intended target while preventing misassignment by excluding codes from adjacent workpieces in different depth zones.
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
The solution effectively reduces the risk of code misassignment by calculating an index based on the depth-of-field region, even in scenarios where workpieces are closely spaced, thereby improving the accuracy of code association with workpieces.
Implementation Method 1
an imaging unit that includes a Scheimpflug optical system including a lens collecting reflected light from the code attached to the workpiece and an image sensor having a light receiving surface inclined with respect to an optical axis of the lens
Implementation Method 2
a lens collecting reflected light from the code attached to the workpiece
Data Source
AI summary
Evaluation of a code misassignment risk is enabled, and occurrence of misassignment of a code is prevented. A code reader includes: an imaging unit that includes a Scheimpflug optical system including a lens and an image sensor having a light receiving surface inclined with respect to an optical axis of the lens, the imaging unit generating and outputting a code image including the code; and a control unit that executes decoding processing on the code image. The control unit calculates an index for evaluating whether or not a code to which the decoding processing has been applied is a code that has been decoded in a depth-of-field region formed substantially perpendicular to a conveying surface of a conveyor by the Scheimpflug optical system based on a result of the decoding processing, and determines whether or not the code is assigned to a wrong workpiece based on the index.