Optical Bandpass Filter for Barcode Scanning Stability
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Solution Overview
Problem
Optical indicia reading terminals face challenges in achieving high motion tolerance while minimizing perceived illumination intensity, which affects image stability and balance, particularly in point-of-sale and other applications where intense illumination is required.
Innovation Solution
Incorporating an optical bandpass filter in the optical path of the image sensor to selectively pass light within specific wavelength ranges and attenuate outside ranges, allowing for balanced color content and reduced perceived illumination, thereby enhancing image stability and motion tolerance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If intense illumination is used to improve scanning capability, then bar code reading performance is improved, but perceived illumination intensity increases causing image instability and reduced motion tolerance
Solution Approach 1:
The patent applies parameter changes by introducing an optical bandpass filter that selectively transmits light within a specific wavelength range (e.g., 400-700nm) while blocking other wavelengths. This changes the spectral composition of the illumination, allowing intense illumination to maintain high scanning capability while the filtered light produces more stable images with reduced perceived intensity, thus resolving the contradiction between productivity and illumination intensity.
2Adaptability or versatility
If broad spectral illumination is used to ensure complete light coverage, then illumination completeness is improved, but image balance and stability deteriorate due to unwanted light wavelengths
Solution Approach 1:
The patent applies local quality by using a bandpass filter to selectively allow only specific local portions of the spectrum (useful wavelengths) to pass through while blocking other portions (unwanted wavelengths). This creates a localized spectral quality improvement, enhancing image stability by eliminating harmful wavelengths while maintaining necessary illumination coverage, thus resolving the contradiction between adaptability and stability.
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 optical bandpass filter improves image stability and balance by reducing unwanted light, allowing for more efficient bar code scanning and decoding, even in environments with varying lighting conditions, while maintaining user satisfaction with reduced perceived illumination intensity.
Implementation Method 1
an optical bandpass filter disposed in an optical path of light incident on the image sensor and adapted to transmit light in first, second and third narrow wavelength bands within the red, green and blue wavelength ranges and to attenuate light at wavelengths outside of the first, second and third narrow wavelength bands
Data Source
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AI summary
Methods for using an optical indicia reading terminal including a housing, a multiple pixel image sensor disposed within the housing, an imaging lens assembly configured to focus an image of decodable indicia on the image sensor, an optical bandpass filter disposed in an optical path of light incident on the image sensor, an analog-to-digital (A/D) converter configured to convert an analog signal read out of the image sensor into a digital signal representative of the analog signal, and processor configured to output a decoded message data corresponding to the decodable indicia by processing the digital signal.