Barcode Scanner Noise Cancellation Circuit for Flickering Ambient Light
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Laser-based barcode scanners face difficulties in functioning properly due to noise interference caused by high-frequency flickering ambient light sources, such as CFLs and LED lamps, which introduce false edge detection and incorrect decoding of barcodes.
Innovation Solution
A barcode scanning device equipped with a light source, a first sensor to detect the barcode signal, a second sensor to detect ambient light signals, and a noise cancelling circuit using differential amplifiers to subtract ambient light noise from the barcode signal, ensuring accurate decoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If energy saving light sources (CFLs and LED lamps) are used to provide illumination, then energy efficiency is improved, but high-frequency flickering noise is introduced that interferes with barcode scanning
Solution Approach 1:
The patent uses the harmful flickering noise from energy-saving lights as a reference signal to identify and subtract the interference component from the barcode scanning signal. By treating the noise as a usable reference, the system converts the harmful effect into a beneficial solution for noise cancellation.
Solution Approach 2:
The patent introduces a noise cancelling circuit as an intermediary component that processes both the scanning signal and the reference noise signal. This intermediary circuit performs differential amplification to eliminate the flickering interference while preserving the barcode information.
2Illumination intensity
If ambient light is present in the scanning environment, then illumination for barcode visibility is improved, but false edge detection occurs leading to incorrect decoding
Solution Approach 1:
The patent extracts the ambient light noise component from the total received signal by using a reference sensor to detect only the noise portion. This extracted noise signal is then subtracted from the main scanning signal, effectively removing the harmful illumination interference while keeping the barcode data intact.
Solution Approach 2:
The patent segments the optical signal detection into two separate functions: one sensor detects the combined scanning signal plus noise, while another reference sensor detects only the ambient noise. This segmentation allows independent processing and selective cancellation of the noise component.
3Measurement precision
If a noise cancelling circuit is added to eliminate flicker interference, then decoding accuracy is improved, but device complexity increases
Solution Approach 1:
The patent employs a differential amplifier as an intermediary noise cancelling circuit that subtracts the reference noise signal from the scanning signal. This simple intermediary component provides effective noise cancellation without requiring complex processing systems, maintaining relatively low device complexity while improving decoding accuracy.
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 cancels out ambient light noise, allowing laser-based barcode scanners to operate accurately even in the presence of high-frequency flickering light sources, improving decoding performance and reliability.
Implementation Method 1
The first sensor is configured to detect a first optical signal indicative of light reflecting off of a barcode
Implementation Method 2
The second sensor is configured to detect a second optical signal indicative of light originating from the at least one ambient light source
Implementation Method 3
The noise cancelling circuit is configured to obtain a noise-cancelled scanning signal from the first and second optical signals
Data Source
AI summary
Systems and methods for cancelling noise caused by the flicker of ambient lights are provided. Such noise cancelling systems and methods may be incorporated in a laser-based barcode scanning device. In one example, a barcode scanning device includes a light source, a first sensor, a second sensor, and a noise cancelling circuit. The light source is configured to emit a beam of light. The first sensor is configured to detect a first optical signal indicative of light reflecting off of a barcode. The reflected light may originate from the light source and from at least one ambient light source in the vicinity of the barcode scanning device. The second sensor is configured to detect a second optical signal indicative of light originating from the at least one ambient light source. The noise cancelling circuit is configured to obtain a noise-cancelled scanning signal from the first and second optical signals.