Barcode Decoding on Cell Phones via Dynamic Exposure Control
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Solution Overview
Problem
Imaging-based barcode scanners face challenges in decoding barcodes on dimly lit cell phones due to specular reflection from the glass window, which causes exposure issues and results in missed or incomplete barcode detection, especially when the phone is tilted to mitigate reflections.
Innovation Solution
An imaging scanner with automatic exposure control that adjusts illumination levels and exposure times based on pixel brightness profiles to enhance barcode visibility, using a method that detects the presence of a mobile device and adjusts settings to ensure adequate exposure for successful decoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the phone is tilted to mitigate specular reflection, then the reflection is reduced, but the barcode becomes dimmer and harder to detect
Solution Approach 1:
The system dynamically adjusts exposure time based on detected brightness levels in different regions of the image. When a barcode region is detected as dimmer than surrounding areas, the exposure time is increased specifically for that region, allowing the scanner to adapt to varying brightness conditions caused by phone tilting and reflection mitigation
Solution Approach 2:
The patent applies different exposure settings to different regions of the image. The system identifies the barcode region and applies localized exposure adjustment to that specific area, rather than uniformly adjusting the entire image. This allows the barcode area to be properly exposed while maintaining appropriate settings for other regions
2Illumination intensity
If exposure time is increased to capture dim barcodes, then barcode visibility improves, but LED blinking becomes more noticeable
Solution Approach 1:
The system applies different exposure times to different regions of the image. The barcode region receives extended exposure time to ensure adequate brightness, while other regions maintain normal exposure settings. This localized approach improves barcode visibility without proportionally increasing LED blinking visibility across the entire image
Solution Approach 2:
The patent applies excessive exposure time specifically to the barcode region rather than uniformly across the entire image. This partial application of extended exposure ensures the barcode is adequately captured while limiting the overall increase in LED blinking that would occur with uniform exposure adjustment
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 scanner effectively decodes barcodes on dimly lit cell phones by adjusting exposure settings, reducing the impact of bright reflections and ensuring adequate brightness for the barcode area, leading to improved scanning performance and reduced noticeable blinking of LEDs.
Implementation Method 1
An imaging sensor generally includes a plurality of photosensitive elements or pixels aligned in one or more arrays
Implementation Method 2
The imaging scanner includes an illumination source and an imaging sensor
Data Source
AI summary
A method of decoding a barcode includes generating a first illumination towards a target object with a first illumination level, capturing a first image during a first exposure time period, and determining a first location and a second location on a scan line in the first image to find a switchover condition. If the switchover condition indicates the presence of a mobile display device, the method further includes generating a second illumination towards the target object with a second illumination level, capturing a second image during a second exposure time period, and decoding the barcode in the second image. Here, at least one of the second illumination level and the second exposure time period is determined based on values of pixels on the scan line between the first location and the second location.