EP0125060A2 — Detecting luminescent security features

Claim 1

Independent Claim 80 words

A method of detecting luminescent security features in or on documents (1), the method comprising illuminating a test document with an interrogation beam; sensing luminescence emitted from the document with sensing means (7); dividing the area over which luminescence is sensed into a plurality of portions; comparing the intensity of the luminescence of each portion with the average intensity of all the portions; and detecting the presence of a security feature (2) if the two intensities satisfy a predetermined relationship.

Claim 2

Independent Claim 80 words

A method of detecting luminescent security features in or on documents (1), the method comprising illuminating a test document with an interrogation beam; sensing luminescence emitted from the document with sensing means (7); dividing the area over which luminescence is sensed into a plurality of portions; comparing the intensity of the luminescence of each portion with the average intensity of all the portions; and detecting the presence of a security feature (2) if the two intensities satisfy a predetermined relationship.

Claim 3

Dependent Claim 40 words

A method according to claim 1, further comprising repeating the sensing step over a plurality of areas of the document, and detecting the presence of a composite security feature (2) if a predetermined arrangement of individual security features are detected.

Claim 4

Dependent Claim 118 words

A method according to claim 2 for detecting a luminescent security thread (2), the method comprising feeding a test document (1) past the sensing means (7) in a direction such that a security thread will extend in the feed direction (19); sensing luminescence emitted from a plurality of sets of adjacent portions of the test document, each set of adjacent portions being aligned transversely to the security thread; determining which portion or portions of each set of portions has emitted luminescence corresponding to a security feature; and detecting the presence of a security thread (2) if security features are detected for each set of portions in positions which are arranged in a manner corresponding to a security thread.

Claim 5

Independent Claim 21 words

A method according to any of claims 1 to 3, further comprising periodically checking for failure of the sensing means (7).

Claim 6

Dependent Claim 16 words

A method according to claim 4, wherein the checking step is carried out between successive documents.

Claim 7

Independent Claim 22 words

A method according to any of the preceding claims, wherein luminescence (L) emitted from both sides of the document (1) is sensed.

Claim 8

Independent Claim 36 words

A method according to any of the preceding claims, wherein the interrogation beam is modulated, and the sensed luminescence is first demodulated prior to the comparing step so that fluorescent and phosphorescent features may be differentiated.

Claim 9

Independent Claim 44 words

A method according to any of claims 1 to 6, wherein the sensing means senses luminescence emitted from the document a predetermined time interval after the test document has been illuminated with the interrogation beam so that fluorescent and phosphorescent features may be differentiated.

Claim 10

Independent Claim 29 words

A method according to any of the preceding claims, wherein the predetermined relationship comprises a minimum predetermined threshold which must be exceeded by the difference between the two intensities.

Claim 11

Dependent Claim 103 words

A detector for detecting luminescent security features in or on documents (1), the detector comprising means (13,15) for illuminating a test document (1) with an interrogation beam; sensing means (7) for sensing luminescence emitted from the document (1); and discriminating means (20-27) for discriminating between luminescence due to a security feature and other luminescence emitted by the document, the discriminating means comprising comparison means (23) for comparing the average intensity of the luminescence emitted over a plurality of adjacent portions of the document with the intensity of each portion and detecting means (26) for detecting whether the compared intensities satisfy a predetermined relationship.

Claim 12

Dependent Claim 103 words

A detector for detecting luminescent security features in or on documents (1), the detector comprising means (13,15) for illuminating a test document (1) with an interrogation beam; sensing means (7) for sensing luminescence emitted from the document (1); and discriminating means (20-27) for discriminating between luminescence due to a security feature and other luminescence emitted by the document, the discriminating means comprising comparison means (23) for comparing the average intensity of the luminescence emitted over a plurality of adjacent portions of the document with the intensity of each portion and detecting means (26) for detecting whether the compared intensities satisfy a predetermined relationship.

Claim 13

Dependent Claim 19 words

A detector according to claim 10, further comprising checking means (28,10) for checking for failure of the sensing means.

Claim 14

Dependent Claim 51 words

A detector according to claim 11, wherein the checking means comprises means (28) for ensuring that no luminescence is sensed when no document is being illuminated; and means (10) for illuminating the sensing means (7) and means (28) to check that the sensing means then senses the apparent presence of luminescence.

Claim 15

Dependent Claim 41 words

A detector according to any of claims 10 to 12, further comprising another sensing means positioned on the opposite side of the document (1) to the one sensing means (7) to detect luminescence emitted from that side of the document (1).

Claim 16

Dependent Claim 21 words

A detector according to any of claims 10 to 13, wherein the or each sensing means comprises a photo-diode array (7).

Claim 17

Dependent Claim 39 words

A detector according to any of claims 10 to 14, for detecting a luminescent security thread (2), wherein the or each sensing means comprises a line of sensors (7), the line being transverse, in use, to the security thread.

Claim 18

Dependent Claim 62 words

Apparatus for automatically detecting the presence of security features in a plurality of documents, the apparatus comprising a detector according to any of claims 10 to 15, means for automatically feeding successive ones of the documents past -the illuminating means (13,15) and the sensing means (7); and means (28) for indicating a document in which a security feature has not been detected.

Claim 19

Dependent Claim 29 words

Apparatus according to claim 16, when dependant on claim 10 or claim 11, further comprising means (28) for indicating the presence of a fault in the or each.sensing means.

Claim 20

Dependent Claim 16 words

Apparatus according to claim 17, wherein the checking means (28, 10) is operable between successive documents.

Detecting luminescent security features

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