Split-Field Imager Subfield Exposure Control
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Solution Overview
Problem
Existing imager-based workstations require multiple imagers to achieve reliable reading of indicia on three-dimensional products, which increases cost and complexity, as a single auto-exposure circuit can only measure illumination light intensity in a single field of view, limiting the ability to adjust exposure in split subfields.
Innovation Solution
A dual-window workstation with two solid-state imagers, each with a field of view split into multiple subfields using optical splitters, and individually controlled illuminators and exposure sensors for each subfield, allowing for adjustable exposure times and redundant coverage of indicia on various product sides.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a single imager with split subfields is used, then the number of imagers is reduced, but the ability to measure illumination light intensity in all subfields is insufficient
Solution Approach 1:
The field of view of the single imager is divided into multiple subfields using optical splitters, with each subfield having its own dedicated exposure sensor. This segmentation allows the system to maintain comprehensive coverage while using fewer imagers, and each subfield can be independently exposed based on its specific lighting conditions
Solution Approach 2:
Multiple exposure sensors are introduced as intermediary devices to measure illumination light intensity in each subfield. These sensors act as mediators between the light sources and the main imager, providing the necessary exposure information for each subfield without requiring multiple full imagers
2Reliability
If multiple imagers are used to cover all product sides, then full coverage is achieved, but cost and system complexity increase
Solution Approach 1:
The workstation uses a single imager with its field of view segmented into multiple subfields through optical splitters. Each subfield is directed at different product sides, achieving comprehensive coverage without requiring multiple complete imagers, thus reducing system complexity while maintaining reliability
Solution Approach 2:
A single imager performs multiple functions by capturing images from different product sides through its split subfields. This multi-functional approach replaces what would traditionally require multiple specialized imagers, reducing both cost and complexity while maintaining full coverage capability
3Ease of operation
If exposure duration is adjusted globally for the imager, then exposure control is simplified, but optimal exposure cannot be achieved for each subfield with different lighting conditions
Solution Approach 1:
The exposure control system is segmented into independent control units for each subfield, with each exposure sensor managing the exposure duration for its corresponding subfield. This allows each subfield to be optimized independently according to its specific lighting conditions while maintaining overall system simplicity
4Reliability
If the scan zone covers all six sides of products, then reading reliability is improved, but the volume of the scan zone grows rapidly requiring more imagers
Solution Approach 1:
The scan zone covering all six sides of products is achieved by segmenting the field of view into multiple subfields, each oriented to cover specific product sides. This segmentation allows comprehensive coverage to be achieved with a single imager rather than requiring multiple imagers, thus maintaining reliability while reducing the quantity of imagers needed
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
Reduces the number of imagers needed while ensuring maximum performance by providing redundant coverage and optimal visibility of indicia, allowing for efficient reading of indicia on products presented in various orientations and positions.
Implementation Method 1
the image sensors detect the return illumination light reflected and/or scattered from the indicia
Implementation Method 2
when at least one laser scan line generated by a laser-based reader sweeps over a symbol
Implementation Method 3
Each imager includes either a global or a rolling shutter to help prevent image blur... Each imager includes an associated illuminator to illuminate the indicia with illumination light
Data Source
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AI summary
A bi-optical, dual window, point-of-transaction workstation images indicia associated with multi-sided products by splitting the field of view of each imager into a plurality of subfields that simultaneously extend through each window over regions of the product. A plurality of energizable illuminators, one for each subfield, illuminates each subfield with illumination light over an adjustable illumination time. The illumination light returned from the indicia in each subfield is captured along respective optical paths from each window to each imager. A plurality of exposure sensors, one for each subfield, and located externally of each imager, senses the returned illumination light in each subfield. A controller energizes each illuminator to illuminate each subfield, deenergizes each illuminator when the returned illumination light sensed by the respective exposure sensors exceeds a threshold, and processes the captured illumination light in at least one of the subfields.