GB2045165A - Magnetic document - Google Patents

Abstract

A magnetic document comprises a support with a track of magnetizable material deposited thereon and capable of receiving and storing a message, the maximum magnetic moment per unit area of the track along a predetermined direction varying from one point to another in such a way that the magnetic configuration detected after removal of one longitudinal half of the track differs from the configuration detected from an entire track. <IMAGE>

Description

SPECIFICATION Magnetic document The present invention relates to a magnetic document and to a method of manufacturing it. A magnetic document comprises a support on which at least one magnetic track is deposited, e.g. credit cards or tickets for operating automatic turnstiles.

More particularly, the invention is concerned with preventing the fraud which is constituted by cutting a magnetic document along the centre line of a magnetic track deposited on the document and then sticking each half onto a support so as to simulate a document of the usual dimensions, thus making two documents out of one.

The invention therefore provides a magnetic document comprising a support with a track of magnetizable material deposited thereon and capable of receiving and storing a message, wherein the degree of magnetizability per unit area of the track along a predetermined direction varies from one point to another in a configuration that is detectable by magnetic reading means, the configuration of varying magnetizability being such that the configuration that would be detected after removal of one longitudinal half of the track differs from the configuration detected from an entire track.

The variation in magnetizability is preferably obtained by depositing a varying quantity of magnetizable material at different points along the track.

Advantageously the magnetizable material is deposited along the track with maxima distributed at regular intervals alternately on either side of the centre line of the track.

In another aspect the invention also provides a method of manufacturing a magnetic document, the method including at least two photogravure passes, one pass depositing the magnetizable material in quantities that vary along the track and distributed on the track in a manner such that the configuration detected by reading one longitudinal half of the track by appropriate means is different from that detected by reading the entire track, the other pass depositing a continuous and uniform layer of magnetizable material.

Preferably the first photogravure pass deposits discontinuous quantities of magnetizable material.

The accompanying sole figure illustrates a nonlimiting embodiment of the invention and shows a magnetic ticket 1 on which a magnetic track 2 is deposited. The magnetic track 2 includes a discontinuous series of deposits of magnetizable material 3. These deposits are spaced at regular intervals along the track, but they are disposed alternately on either side of the centre line of the track 2. A continuous uniform layer of magnetizable material, represented by shading 4 is then deposited over the deposits 3.

The magnetic track 2 is deposited by means of two photogravure passes : a first pass which deposits the discontinuous series of deposits 3; and a second pass which deposits the continuous uniform layer 4.

When the magnetic track 2 passes under a suitable magnetic reading head, a higher magnetic moment is detected from the track each time that a deposit 3 passes under the reading head. The maxima occur at a frequency 2f. If the ticket is cut longitudinally along the centre line of the track, the frequency at which magnetic maxima occur is no longer 2f, but f, thereby indicating fraud regardless of the message recorded on the continuous track 4.

Naturally, the configuration of the deposits 3 could be quite different, it would even be possible to provide a continuous but non-uniform layer, the essential feature is that a difference is detected on reading depending on whether the entire track is passed under the reading head or whether only a half-track is passed.

1. A magnetic document comprising a support with a track of magnetizable material deposited thereon and capable of receiving and storing a message, wherein the degree of magnetizability per unit area of the track along a predetermined direction varies from one point to another in a configuration that is detectable by magnetic reading means, the configuration of varying magnetizability being such that the configuration that would be detected after removal of one longitudinal half of the track differs from the configuration detected from an entire track.

2. A magnetic document according to claim 1, wherein the variation in magnetizability is obtained by depositing a varying quantity of magnetizable material at different points along the track.

3. A magnetic document according to claim 2, wherein the magnetizable material is deposited along the track with maxima distributed at regular intervals alternately on either side of the centre line of the track.

4. A magnetic document substantially as herein described with reference to the sole figure of the accompanying drawing.

5. A method of manufacturing a magnetic document according to any previous claim, the method including at least two photogravure passes, one pass depositing the magnetizable material in quantities that vary along the track and distributed on the track in a manner such that the configuration detected by reading one longitudinal half of the track by appropriate means is different from that detected by reading the entire track, the other pass depositing a continuous and uniform layer of magnetizable material.

6. A method of manufacturing a magnetic document according to claim 5, wherein the first photogravure pass deposits discontinuous quantities of magnetizable material.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (6)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Magnetic document The present invention relates to a magnetic document and to a method of manufacturing it. A magnetic document comprises a support on which at least one magnetic track is deposited, e.g. credit cards or tickets for operating automatic turnstiles. More particularly, the invention is concerned with preventing the fraud which is constituted by cutting a magnetic document along the centre line of a magnetic track deposited on the document and then sticking each half onto a support so as to simulate a document of the usual dimensions, thus making two documents out of one. The invention therefore provides a magnetic document comprising a support with a track of magnetizable material deposited thereon and capable of receiving and storing a message, wherein the degree of magnetizability per unit area of the track along a predetermined direction varies from one point to another in a configuration that is detectable by magnetic reading means, the configuration of varying magnetizability being such that the configuration that would be detected after removal of one longitudinal half of the track differs from the configuration detected from an entire track. The variation in magnetizability is preferably obtained by depositing a varying quantity of magnetizable material at different points along the track. Advantageously the magnetizable material is deposited along the track with maxima distributed at regular intervals alternately on either side of the centre line of the track. In another aspect the invention also provides a method of manufacturing a magnetic document, the method including at least two photogravure passes, one pass depositing the magnetizable material in quantities that vary along the track and distributed on the track in a manner such that the configuration detected by reading one longitudinal half of the track by appropriate means is different from that detected by reading the entire track, the other pass depositing a continuous and uniform layer of magnetizable material. Preferably the first photogravure pass deposits discontinuous quantities of magnetizable material. The accompanying sole figure illustrates a nonlimiting embodiment of the invention and shows a magnetic ticket 1 on which a magnetic track 2 is deposited. The magnetic track 2 includes a discontinuous series of deposits of magnetizable material 3. These deposits are spaced at regular intervals along the track, but they are disposed alternately on either side of the centre line of the track 2. A continuous uniform layer of magnetizable material, represented by shading 4 is then deposited over the deposits 3. The magnetic track 2 is deposited by means of two photogravure passes : a first pass which deposits the discontinuous series of deposits 3; and a second pass which deposits the continuous uniform layer 4. When the magnetic track 2 passes under a suitable magnetic reading head, a higher magnetic moment is detected from the track each time that a deposit 3 passes under the reading head. The maxima occur at a frequency 2f. If the ticket is cut longitudinally along the centre line of the track, the frequency at which magnetic maxima occur is no longer 2f, but f, thereby indicating fraud regardless of the message recorded on the continuous track 4. Naturally, the configuration of the deposits 3 could be quite different, it would even be possible to provide a continuous but non-uniform layer, the essential feature is that a difference is detected on reading depending on whether the entire track is passed under the reading head or whether only a half-track is passed. CLAIMS

1. A magnetic document comprising a support with a track of magnetizable material deposited thereon and capable of receiving and storing a message, wherein the degree of magnetizability per unit area of the track along a predetermined direction varies from one point to another in a configuration that is detectable by magnetic reading means, the configuration of varying magnetizability being such that the configuration that would be detected after removal of one longitudinal half of the track differs from the configuration detected from an entire track.

2. A magnetic document according to claim 1, wherein the variation in magnetizability is obtained by depositing a varying quantity of magnetizable material at different points along the track.

3. A magnetic document according to claim 2, wherein the magnetizable material is deposited along the track with maxima distributed at regular intervals alternately on either side of the centre line of the track.

4. A magnetic document substantially as herein described with reference to the sole figure of the accompanying drawing.

5. A method of manufacturing a magnetic document according to any previous claim, the method including at least two photogravure passes, one pass depositing the magnetizable material in quantities that vary along the track and distributed on the track in a manner such that the configuration detected by reading one longitudinal half of the track by appropriate means is different from that detected by reading the entire track, the other pass depositing a continuous and uniform layer of magnetizable material.

6. A method of manufacturing a magnetic document according to claim 5, wherein the first photogravure pass deposits discontinuous quantities of magnetizable material.