Sensor Calibration for Value Documents Using Transport Correction
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Solution Overview
Problem
Existing methods for calibrating sensors that check documents of value face challenges such as image misalignment and inaccurate magnetic signal corrections due to transport irregularities, leading to potential errors in authenticity and condition checks.
Innovation Solution
A method involving a calibration medium with defined reference areas and markings is transported past the sensor, allowing for the determination of transport properties and correction values to adjust measurement signals, ensuring precise calibration and accurate checks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a calibration medium is transported past the sensor without correction, then the calibration process is simple, but transport irregularities cause measurement errors
Solution Approach 1:
The patent applies preliminary action by determining transport properties (such as position, speed, or orientation) of the calibration medium before performing the actual calibration measurement. This allows the system to pre-calculate correction values based on detected transport deviations, ensuring accurate calibration despite irregularities in the transport process.
Solution Approach 2:
The patent implements feedback by using sensors to detect the actual transport properties of the calibration medium during calibration, comparing these against ideal transport conditions, and automatically applying correction values to compensate for deviations. This closed-loop approach ensures measurement precision while managing system complexity through automated correction.
2Measurement precision
If transport properties are measured and correction values are applied, then calibration precision is improved, but the calibration process becomes more complex
Solution Approach 1:
The system performs preliminary detection of transport properties and pre-calculates correction values before the actual calibration measurement. This preparation phase ensures that when calibration is performed, the corrections are already ready, minimizing additional time requirements while maximizing precision.
Solution Approach 2:
The patent enables continuous calibration by performing transport property detection and correction value application in an integrated, continuous process rather than as separate discrete steps. This maintains the useful action of calibration without significant time loss, as the correction process occurs concurrently with or immediately follows the measurement process.
Data Source
Figure 1a~1c
AI summary
The invention relates to a method for calibrating a sensor designed to check value documents. The sensor records measurement signals of a calibration medium transported past the sensor. From the recorded measurement signals, reference data of the calibration medium are determined, and also a transport property of the calibration medium is determined, e.g. the transport speed or the transport position of the calibration medium. At least one correction value is determined from the transport property. Said correction value is used to correct the recorded reference data of the calibration medium. Following the calibration, the corrected reference data are compared with target data of the calibration medium. The sensor is then optionally adjusted using the corrected reference data.