Bar Code Scanner Imaging Orientation and Depth of Field
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Solution Overview
Problem
Conventional imaging bar code scanners exhibit strong orientation preferences, leading to poor performance when bar codes are presented at non-orthogonal angles, and have limited depth of field due to shallow object distances and wide camera apertures, causing operator discomfort and difficulties in processing small bar codes.
Innovation Solution
The use of imaging devices oriented at non-orthogonal angles, such as +45° or −45°, and multiple cameras with staggered object distances and rapid focus lenses to capture bar codes effectively, allowing for effective magnification and increased depth of field, and employing data processing techniques to combine and validate data from multiple rows of pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If imaging devices are oriented orthogonally to bar codes in preferred orientations, then processing efficiency is improved for those orientations, but performance deteriorates when bar codes are presented at non-orthogonal angles
Solution Approach 1:
The system divides the imaging function into multiple imaging devices, each oriented at different angles (e.g., 0°, 45°, 90°, 135°). Each device specializes in capturing bar codes within its optimal orientation range, allowing the system to maintain high processing efficiency across all bar code orientations by selecting the appropriate device for each scan.
Solution Approach 2:
The system creates a universal bar code scanning capability by combining multiple imaging devices with different orientations. The controller coordinates these devices to provide omnidirectional scanning coverage, making the system adaptable to any bar code presentation angle while maintaining optimal processing efficiency for each orientation.
2Object-affected harmful factors
If a wide camera aperture is used to avoid excessively bright illumination, then operator discomfort is reduced, but depth of field becomes shallow
Solution Approach 1:
The system divides the imaging function across multiple imaging devices positioned at different object distances. This segmentation allows each device to operate with a narrower aperture at its optimized distance, achieving both adequate depth of field for small bar codes and reduced illumination intensity to prevent operator discomfort.
Solution Approach 2:
The system resolves the depth of field limitation by adding the dimension of multiple imaging devices at different distances from the scan window. Instead of relying on a single device with a wide aperture and shallow depth of field, the system uses multiple devices with narrower apertures and greater depths of field, each optimized for specific distance ranges.
3Area of stationary object
If imaging devices are positioned at short object distances, then scanning coverage is improved, but depth of field is reduced and illumination requirements increase
Solution Approach 1:
The system segments the scanning coverage area by positioning multiple imaging devices at different object distances. Each device is responsible for capturing bar codes within its optimal focal range, allowing the system to maintain adequate depth of field for each device while collectively providing comprehensive scan coverage across various distances.
Solution Approach 2:
The system extends the effective scanning coverage by adding the dimension of multiple imaging devices at different distances. This multi-distance arrangement allows each device to operate at its optimal focal distance with adequate depth of field, while the collective coverage of all devices spans a broader range of object distances and maintains comprehensive scan coverage.
Data Source
AI summary
Improved systems and techniques for imaging bar code processing. One or more cameras are deployed in a bar code scanner, oriented so that an imaging device of each camera is oriented such that rows of data elements in the imaging device are oriented nonorthogonally with respect to a preferred orientation of a bar code. One or more imaging devices captures bar code data representing light and dark spaces of the bar code. The captured bar code data is analyzed to create one or more rows of data completely transecting the bar code, and the rows of data are processed to generate a scan signal which is in turn processed to extract bar code data.