Optical Reader Quality Factor Monitoring for Calibration Drift
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Solution Overview
Problem
Optical reader systems face challenges in maintaining calibration over time due to changes in light sources and photo-sensitive devices, leading to slow and costly field service responses when issues arise, as manufacturers are only informed of problems through warranty issues or service complaints.
Innovation Solution
A quality factor (QF) system is introduced to monitor and track the performance of optical readers, using a mid-level gray target to generate a numeric value that indicates performance, allowing for preemptive maintenance and reducing downtime by scheduling service before failures occur.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If optical reader systems operate without continuous monitoring, then device complexity is reduced, but reliability deteriorates due to calibration drift from light source and photo-sensitive device changes
Solution Approach 1:
The optical reader system performs self-diagnosis by automatically monitoring its own light source output and photo-sensitive device response through a control circuit that measures electrical characteristics and generates quality factors, eliminating the need for external monitoring equipment and enabling the system to detect its own calibration drift
Solution Approach 2:
The control circuit continuously measures the electrical characteristics of light sources and photo-sensitive devices, compares readings against baseline calibration data, and generates quality factor indicators that provide feedback on calibration status, allowing the system to detect drift before it affects reading accuracy
2Productivity
If field service is provided only after warranty issues or service complaints, then service cost is reduced, but productivity deteriorates due to extended reader downtime
Solution Approach 1:
The quality factor monitoring system detects calibration drift and performance degradation before they cause complete failure, allowing maintenance to be scheduled in advance during convenient time windows, thereby preventing unplanned downtime and enabling proactive rather than reactive service
Solution Approach 2:
The patent replaces the traditional mechanical service model (physical inspection after failure) with an electronic monitoring system that continuously tracks performance parameters and predicts maintenance needs, substituting automated electronic detection for manual field service intervention
3Manufacturing precision
If comprehensive testing is performed on all readers before shipping, then manufacturing precision is improved, but productivity deteriorates due to extended testing time
Solution Approach 1:
The patent extracts the comprehensive calibration verification process from the pre-shipment testing phase and relocates it to the field operation phase, where quality factors are monitored during actual use, allowing faster initial shipping while maintaining calibration verification through ongoing monitoring
Solution Approach 2:
Instead of performing calibration verification as a one-time pre-shipment action, the system implements continuous monitoring of quality factors during field operation, ensuring calibration accuracy is maintained over time without requiring extended testing periods before shipping
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 QF system enables real-time monitoring and tracking of optical reader performance, allowing for proactive maintenance and reducing the likelihood of field failures, thereby minimizing downtime and service costs.
Implementation Method 1
The illumination source may include a series of light emitting diodes (LEDs) and the sensor array may include a set of photo-transistors. Both the illumination source and the sensor array may be distributed along the bar assembly across the readable width of the document. The light from the LEDs is reflected from the document onto the sensors.
Data Source
AI summary
A method and apparatus for generating and applying quality factors (QFs) to an optical reader. After an optical reader is calibrated, a mid-range gray scale level is selected and scanned. The reader outputs digital numbers (DNs) that are generated for all the pixels that will be responding to the reading of a document. A histogram of the DNs is generated and characteristics of the histogram distribution are calculated and used as QFs. For example, the standard deviation of the histogram may serve as a QF, where a lower standard deviation is preferred. Thresholds and standards may be developed from experience that indicate the operating condition of the reader. The QFs, thus, may be used during manufacturing and for field servicing of the reader.