Barcode Scanner Noise Compensation via Learning Mode
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Solution Overview
Problem
Optical bar code scanning is impaired by noise, which can be mistaken for transitions in the bar code signal, leading to decoding errors and requiring additional processing resources to identify and compensate for noise influences, particularly due to predictable events during the scan process.
Innovation Solution
The scanner operates in a learning mode to identify and log noise patterns, constructing a noise occurrence table that allows for noise elimination or compensation by deactivating the laser or ignoring specific light signals during known noise times, using a noise elimination module to create a command table for minimizing noise effects during operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the scanner continuously monitors and processes all light signals during operation, then decoding accuracy may improve, but processing time increases and throughput decreases
Solution Approach 1:
The system performs preliminary noise characterization during a learning mode before normal operation. The noise occurrence table is constructed in advance by monitoring light signals during learning scans, identifying predictable noise patterns and their timing. During actual bar code scanning, the system uses this pre-built table to quickly identify and ignore noise signals, avoiding the need for complex real-time analysis and thus maintaining high throughput while ensuring accurate decoding.
2Measurement precision
If the scanner operates in learning mode to identify noise patterns, then noise compensation accuracy improves, but initial setup time and operational time are increased
Solution Approach 1:
The system changes operational parameters by switching between learning mode and normal scan mode. During learning mode, the scanner collects data to build the noise occurrence table with specific timing and pattern parameters. Once the table is constructed, the system transitions to normal operation where bar code scans proceed at full speed using the pre-acquired noise information, thus limiting the time spent in learning mode to only when necessary.
Solution Approach 2:
The noise occurrence table is a lightweight data structure that can be quickly constructed and updated. The learning process is designed to be relatively brief, creating a simple lookup table that provides long-term benefits without requiring extensive learning time. The table acts as a disposable or periodically refreshable resource that enables fast noise rejection during normal operation.
3Reliability
If the laser is deactivated during identified noise times, then noise influence is reduced, but scanning speed and throughput may be affected
Solution Approach 1:
The system uses periodic action by deactivating the laser only during specific, predictable time intervals when noise is expected to occur, as identified in the noise occurrence table. Rather than continuous operation or frequent on/off cycling, the laser remains on during normal scanning and is briefly deactivated only during the specific time windows when noise events are predicted, thus maintaining high scan speed while improving signal accuracy during critical measurement periods.
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
This approach reduces decoding errors by identifying and mitigating noise sources, improving scanning efficiency and throughput by eliminating or compensating for noise at predictable times, thereby enhancing the accuracy and speed of bar code detection.
Implementation Method 1
a laser beam 104. The laser beam 104 is directed to a deflector mirror 106 and is reflected to strike a rotating polygonal spinner 108
Implementation Method 2
The scan signal is processed to extract bar code information from light resulting from the reflection of a scan pattern from a bar code into one of the scan windows 116A and 116B and back to the photodetector 118
Data Source
AI summary
Systems and techniques for eliminating or compensating for noise affecting a bar code scanner. A scanner is operated in a learning mode under conditions designed to insure that a scan signal will take on predictable characteristics and noise affecting the scan signal will be easily detectable. During the learning mode, information relating to noise affecting the scan signal and the conditions under which the noise occurs is stored. During normal operation of the scanner, the stored noise information is used in controlling operation of the scanner so as to eliminate or compensate for noise under conditions in which noise has been shown to be susceptible to occur.