Sensor for verifying value documents

Patent metadata

Field	Value
Publication number	US-12450967-B2
Application number	US-202218546463-A
Country	US
Kind code	B2
Filing date	Feb 15, 2022
Priority date	Feb 16, 2021
Publication date	Oct 21, 2025
Grant date	Oct 21, 2025

Abstract

A sensor for verifying value documents and designed to determine the luminescence time constant of a value document that is moved past the sensor for verification purposes, and the provision of a velocity correction of the luminescence time constant of the value document in the sensor. The relative movement between the value document and the sensor causes movement effects, resulting in a distortion of the intensity curve from which the luminescence time constant is derived. The luminescence time constant is corrected using a sensor-specific corrective factor ascertained for the velocity of the movement of the value document during the verification process. For this purpose, different sensor-specific corrective factors are used for different examples of sensors that are nominally identical in design and are part of the same sensor production series.

First claim

The invention claimed is:

1. A method for providing a velocity correction of a luminescence time constant of a value document in a sensor which is configured for measuring a change over time in a luminescence of the value document while the value document is transported past the sensor, and which is configured for determining the luminescence time constant of the value document on the basis of the measured change over time in the luminescence and for verifying the luminescence of the value document, comprising the following steps: a) determining at least one sensor-specific parameter on the basis of a measurement at the sensor or on the basis of a measurement with the aid of the sensor, b) storing the at least one sensor-specific parameter in the sensor, c) providing the velocity correction, which, during the verification of the luminescence of the value document transported past the sensor at a verification transport velocity, is usable for correcting a luminescence time constant determined for the value document, in a correction device of the sensor, wherein the correction device, for the velocity correction of the luminescence time constant of the value document, is configured: on the basis of the at least one sensor-specific parameter stored in the sensor and by means of information made available in the sensor regarding the verification transport velocity of the value document, to determine a sensor-specific correction factor which is applicable to the verification transport velocity of the value document to be verified in each case, and to correct the luminescence time constant determined for the value document with the aid of the sensor-specific correction factor applicable to the verification transport velocity of the value document in order to determine a corrected luminescence time constant for the value document, wherein the sensor is designed to verify the luminescence of the value document on the basis of the corrected luminescence time constant.

2. The method according to claim 1 , wherein a velocity dependence of a sensor-generally applicable correction factor is stored in the sensor, which velocity dependence assigns in each case a sensor-generally applicable correction factor to different possible transport velocities of the value document to be verified, and the sensor-generally applicable correction factor applicable to the verification transport velocity of the value document is used for the velocity correction of the luminescence time constant determined for the value document.

3. The method according to claim 1 , wherein at least one correction assignment, in particular offset value assignment or correction table or correction formula, is stored in the sensor, which correction assignment, for different possible sensor-specific offset values of the sensor, assigns in each case an offset-dictated correction factor to in each case different possible transport velocities of the value document to be verified, and in that during the velocity correction it is provided that on the basis of the correction assignment, in particular on the basis of the offset value assignment or correction table or correction formula, with the aid of the sensor-specific parameter stored in the sensor, the sensor-specific correction factor is determined which is applicable to the sensor-specific parameter of the sensor stored in the sensor and to the verification transport velocity of the value document, and the luminescence time constant of the value document is corrected with the aid of the sensor-specific correction factor determined on the basis of the correction assignment and applicable to the verification transport velocity.

4. The method according to claim 1 , wherein the correction device is configured to determine the sensor-specific correction factor applicable to the verification transport velocity depending on information made available to the sensor regarding the transport direction of the value document to be verified relative to the sensor and/or wherein the correction device is configured to determine the sensor-specific correction factor applicable to the verification transport velocity depending on information made available to the sensor regarding a target value of the luminescence time constant of the value document to be verified.

5. The method according to claim 1 , wherein the sensor-specific parameter stored in the sensor is a sensor-specific offset value of the sensor, which is characteristic of a sensor-specific offset along the transport direction of the value document between an illumination region and a detection region of the sensor, in particular a sensor-specific offset length of the sensor, which indicates the distance along the transport direction of the value document between the illumination region and the detection region.

6. The method according to claim 1 , wherein in step a) when determining the sensor-specific parameter, the following steps are carried out: a1) transporting a reference medium provided with a reference luminescent material past the sensor at a reference transport velocity along a transport direction, wherein the reference luminescent material has a specified luminescence time constant, and a2) measuring the change over time in the luminescence of the reference luminescent material by means of the sensor at the reference transport velocity while the reference medium is transported past, and a3) determining a reference medium time constant of the reference luminescent material for the reference transport velocity on the basis of the change over time in the luminescence of the reference luminescent material measured at the reference transport velocity, and a4) determining a specific sensor-specific correction factor applicable to the reference transport velocity on the basis of the determined reference medium time constant of the reference luminescent material and on the basis of the specified luminescence time constant of the reference luminescent material, and wherein in step b) when storing the sensor-specific parameter in the sensor, the following steps are carried out: b1) storing the specific sensor-specific correction factor applicable to the reference transport velocity as a sensor-specific parameter in the sensor or b2) storing a sensor-specific offset parameter, which was determined on the basis of the specific sensor-specific correction factor and the value of the reference transport velocity, as a sensor-specific parameter, and wherein in step c) when providing the velocity correction, the correction device, for the velocity correction of the luminescence time constant of the value document, is configured to determine, in particular to calculate, the sensor-specific correction factor which is applicable to the verification transport velocity of the value document to be verified in each case by means of information made available to the sensor regarding the verification transport velocity of the value document and on the basis of the specific sensor-specific correction factor stored in the sensor and optionally the value of the reference transport velocity stored in the sensor or on the basis of the sensor-specific offset parameter of the sensor stored in the sensor, if the verification transport velocity does not correspond to the reference transport velocity.

7. The method according to claim 6 , wherein the specific sensor-specific correction factor applicable to the reference transport velocity and the value of the reference transport velocity have been/are stored in the sensor, and for the velocity correction it is provided that on the basis of
the specific sensor-specific correction factor and
the value of the reference transport velocity and
the sensor-generally applicable correction factor applicable to the reference transport velocity
the

Assignees

• Giesecke & Devrient Currency Technology Gmbh

Inventors

• Danhof Julia
• Geiseler Henning
• Deckenbach Wolfgang

Classifications

• G07D7/2075

  Setting acceptance levels or parameters · CPC title

• G07D7/121

  Apparatus characterised by sensor details · CPC title

• G07D7/1205 Primary

  Testing spectral properties · CPC title