Laser Scanner Drive Frequency Offset Monitoring
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Solution Overview
Problem
Existing indicia readers face challenges in accurately determining and maintaining the drive frequency offset from the resonant oscillation frequency of light-deflecting assemblies, leading to variations in performance and increased system startup time due to traditional resonance testing methods.
Innovation Solution
A method that predicts the resonant oscillation frequency of the light-deflecting assembly by monitoring the phase shift between the drive frequency and sense frequency, allowing for adjustments to achieve a desired offset, thereby simplifying the process and reducing variations across devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional resonance testing methods are used to determine drive frequency offset, then the relationship between drive frequency and resonant oscillation frequency can be determined, but unwanted variation in selected drive frequency occurs due to variation in the resonant frequency check method
Solution Approach 1:
The patent employs feedback by continuously monitoring the phase shift between the drive frequency signal and the sense frequency signal from the sense winding. This phase shift feedback is used to predict the resonant oscillation frequency and adjust the drive frequency accordingly, eliminating the need for repeated resonance testing and ensuring consistent drive frequency selection across different devices.
Solution Approach 2:
The patent replaces the mechanical resonance testing method with an electrical phase shift measurement approach. By using the sense winding to generate a sense frequency and measuring the phase shift between this sense frequency and the drive frequency, the system substitutes a more precise electrical measurement method for the traditional mechanical resonance testing, thereby improving both accuracy and consistency.
2Measurement precision
If repeated resonance testing is performed to determine resonant frequency, then the drive frequency offset can be adjusted, but system startup time increases and performance variation occurs across devices
Solution Approach 1:
The patent applies preliminary action by using the sense winding to continuously provide sense frequency information during normal operation. This allows the system to predict resonant frequency changes in advance without needing to perform repeated resonance testing during startup, thereby reducing system startup time while maintaining accurate resonant frequency determination.
3Reliability
If resonance testing is performed frequently to account for resonant frequency changes over time and temperature, then drive frequency accuracy is maintained, but device complexity and operation time increase
Solution Approach 1:
The sense winding serves multiple functions: it generates the sense frequency for phase shift measurement, provides feedback for resonant frequency prediction, and enables continuous monitoring without requiring separate testing hardware. This multi-functionality reduces device complexity while maintaining the ability to accurately track resonant frequency changes over time and temperature.
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 enables more precise determination of the drive frequency settings, improving efficiency and reducing the need for frequent resonance testing, leading to consistent performance and enhanced user experience in indicia readers.
Implementation Method 1
The light-deflecting assembly has a resonant oscillation frequency
Implementation Method 2
The indicia-capturing subsystem includes a sense mechanism (e.g., sense winding) for generating a sense frequency associated with oscillation of the light-deflecting assembly
Data Source
AI summary
A method for operating an indicia reader such as a laser scanner is provided. The method affords a simplified technique for monitoring the offset between the drive frequency and the resonant oscillation frequency of the laser scanner. The phase offset between the drive frequency and the sense frequency is monitored to derive the drive frequency's offset from the resonant oscillation frequency.