U.S. patent application number 10/204497 was filed with the patent office on 2003-05-15 for marking device, method and apparatus for the production thereof and a method for reading a marking device of this type.
Invention is credited to Eberhardt, Wolfgang, Morenzin, Jan, Schondelmaier, Daniel.
Application Number | 20030091867 10/204497 |
Document ID | / |
Family ID | 7631866 |
Filed Date | 2003-05-15 |
United States Patent
Application |
20030091867 |
Kind Code |
A1 |
Morenzin, Jan ; et
al. |
May 15, 2003 |
Marking device, method and apparatus for the production thereof and
a method for reading a marking device of this type
Abstract
The invention relates to a marking device (21) for the
identification of objects, comprising a coding consisting of areas
(24, 25) of differing magnetic properties. The marking device is
characterised in that it has magnetic areas (24, 25) consisting of
a homogeneous, ferromagnetic or ferrimagnetic material, each of
said areas having a magnetic anisotropy with an easy and hard
magnetic axis, whereby areas with a different orientation of the
easy magnetic axis and/or areas with remanence of different
strengths succeed each other in at least one specific direction.
The invention also relates to a method for producing a marking
device of this type and to apparatus for carrying out the
method.
Inventors: |
Morenzin, Jan; (Hennef,
DE) ; Schondelmaier, Daniel; (Titz-Rodingen, DE)
; Eberhardt, Wolfgang; (Berlin, DE) |
Correspondence
Address: |
THE FIRM OF KARL F ROSS
5676 RIVERDALE AVENUE
PO BOX 900
RIVERDALE (BRONX)
NY
10471-0900
US
|
Family ID: |
7631866 |
Appl. No.: |
10/204497 |
Filed: |
October 22, 2002 |
PCT Filed: |
January 10, 2001 |
PCT NO: |
PCT/EP01/00244 |
Current U.S.
Class: |
428/845.5 |
Current CPC
Class: |
G06K 19/12 20130101;
G06K 1/125 20130101; G06K 19/06196 20130101; Y10T 29/49133
20150115; Y10T 29/49131 20150115 |
Class at
Publication: |
428/694.0PR ;
428/694.0GR; 428/694.00B; 428/694.00R |
International
Class: |
G11B 005/66 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 22, 2000 |
DE |
100 08 097.9 |
Claims
1. A marking device 21 for the identification of objects, with a
coding of regions (24, 25) with different magnetic properties,
characterized in that magnetic regions (24, 25) of a homogeneous
ferromagnetic material or ferrimagnetic material are provided which
each have a magnetic anisotropy with magnetic easy and hard axes,
whereby in at least a certain direction, regions with different
orientations of the easy axis and/or regions with remanences of
different amplitude follow one another.
2. A marking device according to claim 1, characterized in that
magnetic regions (24, 25) in the determined direction are directly
adjacent one another.
3. A marking device according to claims 1 or 2, characterized in
that magnetic regions (24, 25) in the determined direction are
spaced apart.
4. A marking device according to claim 3, characterized in that
magnetic regions between the magnetic regions are magnetizable.
5. A marking device according to one of claims 1 to 4,
characterized in that magnetic regions have saturation
magnetizations of equal magnitudes.
6. A method of producing a marking device according to one of
claims 1 to 5, characterized in that a coding layer (23) of a
homogeneous ferromagnetic material or ferrimagnetic material is
applied to a carrier (22) and that regions (24, 25) with magnetic
anistropy with magnetically easier and harder axes are so produced
that at least in a certain direction regions with different
orientations of the easier axis and/or regions with reminances of
the different amplitudes follow one another.
7. The method according to claim 6, characterized in that the
coding layer (23) is so constructed that magnetic regions (24.25)
directly border one another in the certain direction.
8. The method according to one of claims 6 or 7, characterized in
that the coding layer is so constructed that the magnetic regions
are spaced apart in the certain direction.
9. The method according to claim 8, characterized in that the
coding layer is so constructed that the regions between the
magnetic regions are not magnetizable.
10. The method according to one of claims 6 to 9, characterized in
that the coding layer (23) is so constructed that the magnetic
regions (24, 25) have saturation magnetizations of equal
magnitudes.
11. The method according to one of claims 6 to 10, characterized in
that the coding layer (23) is produced by vapor deposition.
12. The method according to one of claims 6 to 11, characterized in
that a protective layer (65, 101, 135) is applied to the coding
layer (63, 64, 100, 134), especially by vapor deposition.
13. The method according to one of claims 6 to 12, characterized in
that the coding layer (63) upon layer build up is impressed with a
nonhomogeneous magnetic field.
14. The method according to claim 13, characterized in that to
produce the magnetic field a magnetizable carrier is
nonhomogeneously magnetized.
15. The method according to claim 13, characterized in that to form
the magnetic field a magnetizable underlay (58) is nonhomogeneously
magnetized and that the carrier (62) is placed on this underlay
(58) and the build up of the coding layer (63) is effected on the
combination of the underlay (58) and the carrier (62).
16. The method according to claim 15, characterized in that a
carrier foil is drawn from a supply and brought together with a
continuously displaced magnetic foil and both are fed through a
coating station in which the coding layer is applied.
17. The method according to claim 16, characterized in that the
carrier foil and magnetic foil are separated downstream of the
coating station.
18. The method according to claim 16 or 17, characterized in that
the magnetic foil is drawn from a supply and the magnetized and
that downstream of the coating station is taken up in a store.
19. The method according to claim 16 or 17, characterized in that
the magnetic foil (58) is spaced endlessly through the coating
station.
20. The method according to claim 19, characterized in that the
magnetic foil (58) is magnetized upstream of the coating station
(47) and downstream of the coating station (47) is demagnetized or
has its magnetization homogenized.
21. The method according to claim 13, characterized in that the
magnetic field is produced by magnetic field generating coils.
22. The apparatus for carrying out the method according to one of
claims 13 to 21, characterized by a) a supply store (61) for a
carrier foil (62); b) a coating station (47) for depositing a
coding layer (63); c) a magnetic field unit (59) juxtaposed with at
least the coating station (47) for producing a nonhomogeneous
magnetic field over the area of the carrier foil (62); d) a
receiving store (66) for taking up the marking device; e) guide
elements (49 to 54) and a drive for feeding the carrier foil (62)
from the supply store (61) through the coating station (47) to the
receiving store (66).
23. The apparatus according to claim 22, characterized in that the
magnetic field unit is arranged upstream of the coating station and
that a magnetizable carrier foil is fed through them.
24. The apparatus according to claim 22, characterized in that the
magnetic field arrangement has a magnetic foil which is
nonhomogeneous magnetized and that the guide elements effect a
meeting of the carrier foil and the magnetic foil upstream of the
coating station.
25. The apparatus according to claim 24, characterized in that a
supply for the magnetic foil is provided upstream of the coating
station and that the magnetic field unit has a magnetization device
which is disposed between the supply store and the coating
station.
26. The apparatus according to claim 24, characterized in that the
magnetic field is formed with an endless configuration and is
passed by the guide elements together with the carrier foil through
the coating station.
27. The apparatus according to claim 26, characterized in that the
magnetic field unit has a magnetizing device located in the travel
direction of the carrier foil upstream of the coating station and
generates a nonhomogeneous magnetic field, and that a quenching
device for demagnetization or homogenizing the magnetic field
between the coating station and the magnetizing device.
28. The apparatus according to claim 26 or 27, characterized in
that the magnetic foil is stretched over a support roll which is
associated with the coating station.
29. The apparatus according to claim 22, characterized in that the
coating station (47) is associated with a support roll (49) over
the roll periphery (58) of which the carrier foil is passed through
the coating station (47) and that the roll periphery (58) is
configured to be magnetizable.
30. The apparatus according to claim 29, characterized in that the
magnetic field device has a magnetizing unit (59) for magnetizing
the roll periphery (58) which generates a nonhomogeneous magnetic
field and that a quenching device (60) is provided for
demagnetization or homogenizing the magnetic field.
31. The apparatus according to one of claims 28 or 30 characterized
in that the roll periphery has a magnetizable coating (58).
32. The apparatus according to one of claims 29 or 31,
characterized in that the quenching device (60) and the magnetizing
unit (59) are disposed in the direction of rotation of the support
roll (57) one after the other in the region of the support roll
(47) which is free from the carrier foil (62).
33. The apparatus according to claim 22, characterized in that the
magnetic field unit has a plurality of magnetic field generating
coils.
34. The apparatus according to claim 33, characterized in that the
coils are arranged in the region of the surface of a carrier roll
over whose roll periphery the carrier foil is fed through the
coating station.
35. The apparatus according to one of claims 22 to 34,
characterized in that at least the coating station has a heating
device for generating a homogeneous temperature field.
36. The apparatus according to one of claims 22 to 35,
characterized in that a further coating station (48) is provided
for applying a protective coating (65) to the coding layer.
37. The apparatus according to one of claims 22 to 36,
characterized in that the coating stations (47, 48) have at least
one vapor deposition unit.
38. The apparatus according to one of claims 22 to 37,
characterized in that the supply store or the supply stores and the
receiving store or the receiving stores are configured as supply
rolls (61) or storage rolls (66).
39. The apparatus according to one of claims 22 to 38,
characterized in that the coating stations (47, 48) have at least
one carrier roll (49, 50) over whose roll peripheries the carrier
foil (62) is fed.
40. The method according to one of claims 6 to 12, characterized in
that the regions have layers formed by inclined vapor deposition on
the surface of the carrier (89), whereby at least two different
vapor deposition directions are used.
41. The method according to claim 40, characterized in that the
vapor deposition directions are effected by identically oriented
magnetic fields.
42. The method according to one of claims 40 and 41, characterized
in that the vapor deposition in a first vapor deposition direction
regions of the carrier (89) are covered by a first mask and that
during the vapor deposition in a second vapor deposition direction
at least the regions of the carrier (89) which were vapor deposited
with the first vapor deposition direction are covered with a second
mask (95).
43. The method according to claim 42, characterized in that in the
vapor deposition in the second vapor deposition direction, regions
have not theretofore been vapor deposited are also covered by the
second mask and at least a portion of these regions, after removal
of the second mask and application of a third mask are vapor
deposited in a third vapor deposition direction.
44. The method according to claim 42, characterized in that a
carrier foil (89) and at least two masking foils (91) and (95) are
drawn from respective supplies (88, 90, 94) and before each vapor
deposition, the carrier foil (89) and one of the masking foils (91,
95) are brought together and the vapor deposition is then effected
from the side of the masking foil (91, 95) and the masking foil
(91) is again separated from the carrier foil (89) before the
carrier foil (89) is brought together with a further masking foil
together.
45. The method according to claim 44, characterized in that the
masking foils (91, 95) are each provided with cutouts (93, 97)
after being withdrawn from the supply (90, 94) and before being
brought together with the carrier foil (89).
46. The apparatus for carrying out the method according to one of
claims 40 to 45, characterized by: a) a supply store 88 for a
carrier foil (89); b) a plurality of coating stations (72, 73) for
vapor depositing the carrier foil (89) in different vapor
deposition directions; c) a number of supply stores (90, 94) have
masking foils (90, 95) corresponding in number to the number of
coating stations (72, 73); d) receiving stores for taking up the
masking foils; e) a receiving store (104) for taking up the marking
device; f) guide elements (75 to 83) and a drive for feeding the
carrier foil (89) from the supply store (78) through the coating
stations (72, 73) to the receiving store (104) and for feeding
together the carrier foil (89) with each of the masking foils (91,
95) upstream of a coating station (72, 73) and for separating the
carrier foil (89) and the masking foil (91, 95) downstream of a
coating station.
47. The apparatus according to claim 46, characterized in that each
coating station (72, 73) is associated with a supply store (90, 94)
for a masking foil (91, 95) and a receiving store (99, 101) for
taking up the masking foil (91, 95).
48. The apparatus according to one of claims 46 or 47,
characterized in that between supply stores (90, 94) for the
masking foil (91, 95) and the meeting of the masking foils (91, 95)
and the carrier foil (89), respective mask forming stations (92,
96) are arranged for producing cutouts (93, 97) in the masking
foils (91, 95).
49. The apparatus according to claim 48, characterized in that the
mask forming stations (92, 96) has a laser burning unit.
50. The apparatus according to claim 49, characterized in that the
mask forming stations (92, 96) each have a control device for
varying the position of the laser burning unit.
51. The apparatus according to one of claims 46 to 50,
characterized in that a further coating station (74) is provided
for providing a protective layer (103) on the coding layer
(102).
52. The apparatus according to one of claims 46 to 51,
characterized in that the supply stores are configured as supply
rolls (88, 90, 94) and the receiving stores as storage rolls (99,
101, 104).
53. The apparatus according to one of claims 46 to 52,
characterized in that the coating stations (72, 73, 74) have
carrier rolls (75, 76, 77) under whose roll peripheries the carrier
foil (89) and the masking foils (91, 95) are guided.
54. The method according to claims 6 to 12, characterized in that
at least one homogenized magnetized layer is created and the layer
is subjected to: a) a homogeneous magnetic field and a
nonhomogeneous temperature field; or b) a nonhomogeneous magnetic
field and a homogeneous temperature field; or c) a nonhomogeneous
magnetic field and a temperature field, whereby the temperature
lies above the Curie temperature of the layer.
55. The method according to claim 54, characterized in that to
create the magnetic field, magnetizable carrier is magnetized.
56. The method according to claim 54, characterized in that to
create the magnetic field, magnetizable underlay is magnetized and
that the carrier with the layer is placed on this underlay and the
combination of the underlay and carrier is subjected to the
temperature field.
57. The method according to claim 56, characterized in that a
carrier foil is withdrawn from a supply and brought together with a
continuously displaced magnetic foil as an underlay and both are
fed through a heating station.
58. The method according to claim 57, characterized in that a
carrier foil and magnetic foil are separated downstream of the
heating station.
59. The method according to one of claims 57 and 58, characterized
in that the magnetic foil is drawn from a supply and then
magnetized and downstream of the heating station is taken up in a
store.
60. The method according to one of claims 57 and 58, characterized
in that the magnetic foil is shaped in an endless path through the
heating station.
61. The method according to claim 60, characterized in that the
magnetic foil is magnetized upstream of the heating station and
demagnetized downstream of the heating station or has its
magnetization homogenized.
62. The apparatus for carrying out the method according to one of
the claims 54 to 61, characterized by: a) a supply store for a
carrier foil; b) a treatment station with a magnetizing unit and a
heating unit; c) a receiving store for taking up the marking
device; d) guide elements and a drive for feeding the carrier foil
from the supply store through the treatment station to the
receiving store.
63. The apparatus according to 62, characterized by: a) a coating
station for applying a homogenizingly magnetized coating to the
carrier foil; b) guide elements and a drive for feeding the carrier
foil from a supply store through the coating station and the
treating station to the receiving store.
64. The apparatus according to one of claims 62 to 63,
characterized in that the magnetizing unit has a magnetic foil
which is magnetized and that the guide elements effect a meeting of
the carrier foil and the magnetic foil upstream of the treating
station.
65. The apparatus according to claim 64, characterized in that a
supply store for the magnetic foil is provided upstream of
treatment station and a receiving store is provided downstream of
the treating station, and that the magnetizing unit is disposed
between the supply store and the heating unit.
66. The apparatus according to claim 64, characterized in that the
magnetic foil has an endless configuration and is passed by the
guide elements through the heating unit together with the carrier
foil.
67. The apparatus according to claim 66, characterized in that the
magnetizing unit is disposed in the travel direction of the carrier
foil upstream of the heating unit and produces a nonhomogeneous
magnetic field and that a quenching device is provided between the
heating unit and the magnetizing unit for demagnetization or
homogenizing the magnetic field.
68. The apparatus according to claims 66 or 67, characterized in
that the magnetic foil for stretch over a support roll which is
associated with the treating station.
69. The apparatus according to claim 62, characterized in that the
treating station is associated with a support roll over whose roll
periphery the carrier foil is advanced based the treating station
and that the roll periphery is of a magnetizable configuration.
70. The apparatus according to claim 69, characterized in that the
magnetization unit produces a nonhomogeneous magnetic field and
that a quenching device for demagnetization or homogenization of
the magnetic field.
71. The apparatus according to claims (69, 70), characterized in
that the roll periphery has a magnetizable coating.
72. The apparatus according to claims 70 or 71, characterized in
that the quenching unit and the magnetization unit follow one
another in the direction of rotation of the support roll in the
region of the support roll which is free from the carrier foil.
73. The apparatus according to one of claims 62 to 72,
characterized in that the treating station has heating devices for
local heating.
74. The apparatus according to claim 73, characterized in that the
heating device or devices have at least one laser.
75. The apparatus according to one of claims 73 to 74,
characterized in that the treating station has a magnetizing device
for producing a homogenized magnetic field.
76. The apparatus according to claim 75, characterized in that the
treating station has a heating unit for producing a homogeneous
temperature field as well as a magnetizing unit for producing a
nonhomogeneous magnetic field.
77. The apparatus according to one of claims 62 to 76,
characterized in that a further coating station is provided for
applying a protective layer to the second layer.
78. The apparatus according to one of claims 62 to 77,
characterized in that the coating station has one or more vapor
deposition units.
79. The apparatus according to one of claims 62 to 77,
characterized in that the supply store is formed as a supply roll
and the receiving store as a storage roll.
80. The apparatus of claims 63 to 79, characterized in that the
coating station and the treating station have carrier rolls over
whose roll peripheries the carrier foil is fed.
81. The method defined in one of claims 6 to 12, characterized in
that at least one homogeneous magnetized layer (133) is formed and
the layer (133) is locally so subjected to an ion bombardment that
it is locally caused to have a variation in its easy axis and/or
its remanence.
82. The method according to claim 81 characterized in that the ion
bombardment is effected with the aid of a focused ion beam.
83. The method according to claim 81, characterized in that the ion
bombardment is effected on an areawide basis and in the region of
the carrier (132) a nonhomogeneous electric charge field is
produced.
84. The method according to one of claims 81 to 83, characterized
in that an electrically chargeable carrier is charged electrically
nonhomogeneously prior to the ion bombardment.
85. The method according to claim 83, characterized in that an
electrically chargeable underlay (129) is nonhomogeneous
electrically charged and that the carrier (132) placed on this
underlay (129) and the ion bombardment is effected on the
combination of the underlay (129) and the carrier (132).
86. The method according to claim 85, characterized in that a
carrier foil is drawn from a supply and after a coating is brought
together with a continuously improved charging foil (129) and both
are subjected to ion bombardment.
87. The method according to claim 86, characterized in that the
carrier foil and charging foil are separated after the ion
bombardment.
88. The method according to one of claims 86 or 87, characterized
in that the charging foil is drawn from a supply and then charged
and after the ion bombardment is taken up in a store.
89. The method according to one of claims 86 or 87, characterized
in that a charging foil (129) is circulated as an underlay through
an ion bombardment station (113) and the charging foil (129)
upstream of the ion bombardment station (113) is charged and
downstream of the ion bombardment (113) is discharged or has its
electric homogenized.
90. The method according to one of claims 81 or 82, characterized
in that a carrier foil and masking foil are continuously drawn from
respective supply and brought together and that the ion bombardment
is then effected from the side of the masking foil and the masking
foil is then separated from the carrier foil.
91. The method according to claim 90, characterized in that the
masking foil after being withdrawn from the supply and before being
brought together with the carrier foil is provided with
cutouts.
92. The apparatus for carrying out the method according to one of
claims 81 to 91, characterized by: a) a supply store (131) for a
carrier foil (132); b) an ion bombardment station (113) for the
bombardment of the layer (133); c) a receiving store (136) for the
marking device; d) guide elements (115) through (123) and a drive
for displacing the carrier foil (132) from the supply store (131)
through the ion bombardment station (113) to the receiving store
(136).
93. The device according to claim 92, characterized by: a) a
coating station (112) for applying a homogeneous magnetized layer
(133) to the carrier foil (132); b) guide elements (115) through
(123) and a drive for feeding the carrier foil (132) from the
supply store (131) through the coating station (112) and the ion
bombardment station (113) to the receiving store.
94. The apparatus according to one of claims 92, 93, characterized
in that the ion bombardment station has a focused ion beam and a
control device is provided for the targeted control of the ion
beam.
95. The apparatus according to one of claims 92, 93, characterized
in that an electrically chargeable carrier foil is passed through
the ion bombardment station and is provided with a nonhomogeneous
electric charge by a charging unit.
96. The apparatus according to one of claims 92, 93, characterized
in that the ion bombardment station has an electrically chargeable
charging foil passed through which is provided with a
nonhomogeneous electric charge and that the guide elements effect a
meeting of the carrier foil and charging foil upstream of the ion
bombardment station.
97. The apparatus according to claim 96, characterized in that a
supply store is provided for the charging foil upstream of the ion
bombardment station and a receiving store is provided downstream of
the ion bombardment station and a charging unit is provided for the
nonhomogeneous charging of the charging foil between the supply
store and the ion bombardment station.
98. The apparatus according to claim 96, characterized in that the
charging foil has an endless configuration and is based via the
guide elements together with the carrier foil through the ion
bombardment station and that the charging device in the travel
direction of the carrier foil is provided upstream of the ion
bombardment station and a quenching device is provided between the
ion bombardment station and the charging device for discharging or
homogenizing the electric charge.
99. The apparatus according to claim 98, characterized in that the
charging foil for stretching over a support roll which is
associated with the ion bombardment station.
100. The apparatus according to one of claims 92, 93, characterized
in that the ion bombardment station (113) is associated with a
support roll (116) over the roll periphery (129) of which the
carrier foil (132) is passed through the ion bombardment station
(113) and that the roll periphery (129) is chargeable with an
electric charge whereby a charging unit (128) is provided for
charging the roll periphery (129) and a quenching device (130) is
provided for discharging or homogenizing the electric charge of the
roll periphery (129).
101. The apparatus according to claim 100, characterized in that
the roll periphery has a coating chargeable with an electric
charge.
102. The apparatus according to one of claims 98 to 101,
characterized in that the discharging unit 130 and the charging
unit (128) are provided one after the other in the rotation
direction of the support roll (116) in a region of the support roll
(116) which is free from the carrier roll (132).
103. The apparatus according to one of claims 92, 93, characterized
in that the ion bombardment station has a masking foil based
therethrough and that the guide elements effect a meeting of the
carrier foil and masking foil upstream of the ion bombardment
station in such manner that the ion bombardment is effected from
the side of the masking foil and that the guide elements separate
the carrier foil and masking foil downstream of the ion
bombardment.
104. The apparatus according to claim 103, characterized in that
between a supply store for the masking foil and the meeting of the
masking foil and carrier foil a mask forming station is proposed
for producing cutouts in the masking foil.
105. The apparatus according to claim 104, characterized in that
the mask forming station has a laser burning device.
106. The apparatus according to claim 104, characterized in that
the mask forming station has a control device for varying the
position of the laser burning device.
107. The apparatus according to one of claims 92 to 106,
characterized in that a further coating station (114) is provided
for applying a protective layer 135 on the layer 133.
108. The apparatus according to one of claims 93 to 107,
characterized in that the coating stations (112, 114) have at least
one vapor deposition unit (124, 125).
109. The apparatus according to one of claims 92 to 108,
characterized in that the supply store is configured as a supply
roll and the receiving store as a storage roll.
110. The apparatus according to one of claims 93 to 109,
characterized in that the coating station and the ion bombardment
station have carrier rolls over the roll peripheries of which the
carrier foil is fed.
111. A method of reading a marking device according to one of
claims 1 to 5 with the aid of a magnetic field sensor,
characterized in that the coding is subjected to at least two
reading processes whereby one reading process is effected in a zero
field and a reading process is effected in an external magnetic
field or the reading processes are effected in different external
magnetic field.
112. The method according to claim 111, characterized in that one
reading process is carried out with saturation magnetization.
113. The method for reading marking devices according to one of
claims 1 to 5 with the aid of magnetic field sensor characterized
in that at least one reading process is carried out in the
remanence.
114. The method for reading marking devices according to one of
claims 1 to 5 with the aid of magnetic field sensor characterized
in that at least one reading process is carried out in the flux
change at the boundary between two magnetic regions is
detected.
115. The method for reading marking devices according to one of
claims 1 to 5 with the aid of magnetic field sensor characterized
in that at least two reading processes are carried out without an
external magnetic field and that the coding before a reading
process is magnetized in one direction and before a further reading
process is magnetized in another direction up to saturation.
Description
[0001] The invention relates to a marking device for the
identification of objects, with a coding of regions with different
magnetic characteristics, a method and apparatus for making the
marking device as well as a method of reading such a marking
device.
[0002] For the marking and thus the individual correlation and
verification of check cards, credit cards, access cards, electronic
keys or the like, a variety of magnetic codings are used, usually
mainly in the form of a so-called magnetic strip. For the coding, a
permanent magnetic layer is selectively magnetized, i.e. regionally
magnetized so that regions of different magnetization result,
whereby in the sense of the present description, also nonmagnetized
regions, thus regions at which the magnetization are zero are
included. With corresponding magnetic field sensors, the magnetic
signature or coding can be detected and processing can then be
carried out for the corresponding respective purpose.
[0003] There are numerous different proposals for the configuration
of the magnetic strips. In U.S. Pat. No. 4,650,978, the naturally
random variations of the magnetic characteristic of a magnetic
strip, having their origins in variations in coercivity,
granularity, layer thickness, surface profile and especially from
random variations in the hysteresis loops and the magnetic
histories from which they derive, can be used. The methods of U.S.
Pat. Nos. 5,616,904 and 4,837,426 for coding are similar. The
magnetic structures are digitalized in an appropriate form and used
for identification of the objects. A drawback is that the magnetic
strips can be manipulated relatively simply and are unstable with
respect to external magnetic fields.
[0004] In U.S. Pat. Nos. 5,480,685 and 5,972,438, magnetic strips
are described in which magnetic particles are incorporated in a
binder matrix, whereby the magnetic strips have respectively two
layers of different coercivities. The magnetic strips of U.S. Pat.
No. 5,177,344 also have magnetic particles within a binder matrix
whereby the magnetic particles are so influenced by the application
of an external magnetic failed so that they have magnetic regions
of different characteristics. This kind of magnetic strips have the
drawback that the magnetic structures can be subsequently altered
in that the binder can be heated and the magnetic particles newly
oriented by external magnetic fields.
[0005] With the magnetic strips of U.S. Pat. No. 5,365,586, a
multiplicity of microcrystalline structures are arranged in a
random pattern. The magnetic strips are then subjected to a
saturation magnetization, whereby the remnant noise is read out and
used for identification.
[0006] In U.S. Pat. No. 5,254,843, the random variations in the
time sequence of the flux changes in conventional magnetic bands
and strips are used are drawn upon for identification of the
respective objects. Here as well, the random structure can easily
be reproduced upon recognition. Aside from this, the method
requires a randomness of the variations with time which is not
always produced for certain in machine writing.
[0007] In the PCT/EP99/08433 which has not been prepublished, a
marking device is proposed in which the coding has a magnetic base
layer and a magnetic coding layer which cooperate so that over the
extent of the base layer and coding layer, there are regions with
nonparallel or antiparallel magnetic coupling. Use is here made of
the effect of magnetic intermediate layer coupling. The marking
device has the advantage of a highly characteristic property which
deviates from the usual magnetic marking upon the application of
external magnetic fields which is especially that, while the
saturation magnetic field blanks out the nonparallel or
antiparallel coupling, the original magnetization is restored,
however, after removal of the external magnetic field. The coding
can thus not be extinguished by external magnetic fields. In
addition, use can be made of the effect that magnetic coding which
has weakened, for example, because of long storage times or
so-called lost magnetic codings, can be reactivated by application
of a saturation magnetic field.
[0008] The invention has as its object the provision of a marking
device of the type described at the outset which has a durable
coding which is difficult to manipulate and is insensitive to
external effects. It should also enable a verification without data
connection to an external computer. A further object is to provide
a method and apparatus for producing such a marking device.
[0009] The first part of the above mentioned object is achieved
according to the invention in that magnetic regions are provided of
a homogeneous ferromagnetic or ferrimagnetic material that has
respectively magnetic anisotropy with magnetically soft and
magnetically hard axes [easier and harder axes], whereby in at
least one predetermined direction--this is then the intended
readout direction--regions with different directions of the easy
magnetization axes and/or regions with remanences of different
magnitudes follow one another. The basic concept is thus a
provision of a spatial distribution of the magnetic anistropy with
respective magnetically soft and hard axes. Such an anisotropy can
also be designated as bidirectional anisotropy. It is insensitive
to external influences to the extent that the ferromagnetic or
ferrimagnetic material has a Curie temperature which is
significantly above room temperature, preferably above 150.degree.
C. as is the case with the ferromagnetic materials Co or NiFe. Thus
when reference is made to homogeneous materials, it should be
understood that these include elemental substances as well as
alloys or chemical compounds of such substances like oxides, to the
extent that they, over the extent of the coding disregarding
possible crystallinity--remain uniform and do not form a matrix
system or the like.
[0010] Advantageously, the marking device is such that the magnetic
regions directly bound one another in the predetermined direction.
This does not exclude an arrangement in which the magnetic regions
are also spaced from one another in the preferred direction whereby
the regions between the magnetic regions can be formed as
nonmagnetizeable.
[0011] With the invention it is advantageous when the magnetic
regions have saturation magnetization which are of equal
magnitude.
[0012] By applying to the coding an external magnetic field up to
the saturation range, there is a homogeneous magnetization over the
extent of the coding which forms a reference and enables a
verification test. It will be selfunderstood that this is not a
compulsory requirement since the saturation magnetization can also
vary over the extent of the coding. When this variation is stored,
it can be determined by the verification test, whether a
manipulation has occurred or not. The coding as such is stored in
terms of the distribution of the magnetic bias or an anisotropy.
The marking device of the invention can be produced by applying a
coding layer of a homogeneous or ferromagnetic or ferrimagnetic
carrier and then generating regions of magnetic anisotropy with
magnetically harder or softer axes which in at least one direction
have regions with different directions of the soft axis and/or
regions with remanences of different magnitudes following one
another. This can be accomplished with the magnetic regions
directly bounding one another in succession in the preferred
direction and/or by having them spaced apart.
[0013] Since the coding layer is of relatively thin configuration,
it has been found to be desirable to make use of vapor deposition
technology for building up the layer structure, i.e. thermal vapor
deposition, sputtering or the like. The coding layer can be
provided with a protective layer, for example, of DLC (Diamond Like
Carbon) or SiC, which preferably also is applied by vapor
deposition.
[0014] The impression of the magnetic anisotropy can be effected in
a simple manner in that the coding layer can be subjected to a
nonhomogeneous magnetic field during the build up of the layer. The
distribution of the nonhomogeneity of this magnetic field enables a
pattern of different magnetic anisotropies to be provided and the
coding layer to be deposited with a uniform layer thickness.
[0015] The magnetic field, for example, can be generated by
nonhomogeneously magnetizing a magnetizable carrier or a
magnetizable underlay for the carrier. In the latter case, the
carrier is placed on the underlay and the coding layer is built up
on the combination of the underlay and carrier.
[0016] The marking device can be especially economically fabricated
when a carrier foil is drawn from a supply and brought together
with a continuously displaced magnetic foil and both are fed
through a coating station in which the coding layer is applied.
Then the carrier foil and the magnetic foil should be again
separated. It is advantageous to draw the magnetic foil also from a
supply and then magnetize it and downstream of the coating station
to take it up again in a store. It is especially advantageous if
the magnetic foil is passed in an endless path through the coating
station. In order to produce such a varying nonhomogeneity of the
magnetic field, the magnetic foils should be individually
magnetized upstream of the coating station and downstream of the
coating station should be again demagnetized or have their
demagnetization homogenized. Instead of a magnetic foil, the
magnetic field can also be created by means of generating
coils.
[0017] An apparatus for carrying out the aforedescribed method is
characterized by
[0018] a) a supply store for a carrier foil;
[0019] b) a coating station for forming the coding layer;
[0020] c) a magnetic field unit juxtaposed at least with the
coating station for producing a nonhomogeneous magnetic field over
the area of the carrier foil;
[0021] d) a receiving store for the take up of the marking
device;
[0022] e) guide elements and a drive for feeding the carrier foil
from the supply store through the coating station to the receiving
store.
[0023] With this apparatus, it can be provided that the magnetic
field unit will be arranged upstream of the coating station and
that the magnetizable carrier foil is passed through it. Instead,
the magnetic field unit can have a magnetic foil which is
magnetized nonhomogeneously, whereby the guide elements effect a
joining of the carrier foil and the magnetic foil upstream of the
coating station. In a concrete manner this can be achieved by
providing a supply store for the magnetic foil upstream of the
coating station and a receiving store downstream of the coating
station and a magnetic field unit which has a magnetizing device
which is arranged between the supply store and the coating
station.
[0024] As an alternative thereto, however, the magnetic foil can
also have an endless configuration and be fed via the guide
elements through the carrier foil through the coating station.
Advantageously, the magnetic field unit should then include a
magnetizing unit in the travel direction of the carrier foil which
is upstream of the coating station and which produces a
nonhomogeneous magnetic field, while a quenching device for
demagnetization or homogenization of the magnetic field is provided
between the coating station and the magnetizing unit. The magnetic
foil can, for example, be stretched across a support roll which is
juxtaposed with the coating station and over which the carrier foil
travels. Instead, however, the roll periphery itself can be
configured to be magnetizable and here as well a magnetizing unit
can be provided for magnetizing the roll periphery and a quenching
unit can be provided for demagnetizing or homogenizing the magnetic
field. The roll periphery can be provided with a magnetizable
coating. In all cases, the quenching device and the magnetizing
device should be provided in the direction of rotation of the
support roll one after the other in a region of the roll periphery
which is free from the carrier foil.
[0025] Alternatively, it can be provided that the magnetic field
unit have a multiplicity of magnetic field generating coils. These
coils can be arranged in the vicinity of the surface of a carrier
roll over the roll periphery of which the carrier foil is guided
through the coating station so that during the vapor deposition, a
nonhomogeneous magnetic field prevails. According to a further
feature of the invention, at least the coating station is provided
with a heating unit for producing a homogeneous field preferably
above the Curie temperature.
[0026] It is also proposed to provide a further coating station to
apply a protective layer on the coding layer. In this case, it is
desirable for the coating stations to have vapor deposition units
for application of the coding layer by means of thermal vapor
deposition or sputtering. The supply store or receiving store can
advantageously be formed as a supply roll or as a storage roll.
[0027] The method according to the invention can also be so
configured that the magnetic region has a vapor deposition device
which is inclined to the surface of the carrier whereby with
reference to the plane of the carrier at least two different vapor
deposition directions are provided. In this manner alone, the
anisotropic distribution according to the invention can be achieved
with different directions of the easy magnetization access. This
effect can, however, also be amplified by the simultaneous
impression of a preferably nonhomogeneous magnetic field which is
respectively codirectional with the vapor deposition device.
[0028] More concretely stated, the aforedescribed method can be so
carried out that for the vapor deposition in a first vapor
deposition direction region, the carrier is covered with a first
mask and that in the vapor deposition in a second vapor deposition
direction at least the regions of the carrier which the first vapor
device formed a deposit upon are covered with a second mask. Then
the first and second vapor deposition units can also be identical
when they include units with the aid of which the vapor deposition
direction can be altered. It is possible that in the vapor
deposition in the second vapor deposition direction with the second
mask, regions which had not been covered previously be vapor
deposition could be covered and at least a portion of these
regions, after removal of the second mask and the application of a
third mask, can be vapor deposited in a third vapor deposition
direction.
[0029] In order to be able to make the marking device in a
continuous process, the invention provides that a carrier foil and
at least two masking foils are drawn from respective supplies and
before each vapor deposition, the carrier foil and one of the
masking foils are brought together and the vapor deposition carried
out from the side of the masking foil and the masking foil again be
separated from the carrier before the carrier foil is combined with
a further masking foil. The masking foil can be provided with a
certain mask pattern already before its withdrawal from the supply.
Alternatively thereto it is proposed that the masking foil once
withdrawn from the supply but before being brought together with
the carrier foil, be provided with cutouts. An apparatus for
carrying out the method is characterized by
[0030] a) a supply store for a carrier foil;
[0031] b) a plurality of coating stations for vapor depositing on
the carrier foil in different vapor deposition directions;
[0032] c) a number of supply stores for a masking foil
corresponding in number to the number of coating stations;
[0033] d) receiving stores for taking up the masking foils;
[0034] e) a receiving store for taking up the marking device;
[0035] f) guide elements and a drive for feeding the carrier foil
from the supply store through the coating stations to a receiving
store and for feeding each of the masking foils together with the
carrier foil upstream of a coating station and for separating the
carrier foil and the masking foil downstream of a coating
station.
[0036] Advantageously, each coating station has a supply store for
a masking foil and a receiving store for the take up of the masking
foil. Between each supply store for the masking foil and the
junction for the masking foil and the carrier foil, respective mask
forming stations can be provided to produce cutouts in the masking
foil and thus impress upon each masking foil an individual mask
pattern. The mask forming stations can, for example, have a laser
burning device which has a control unit for varying the position of
the laser burning device.
[0037] Also with this apparatus, a further coating station can be
provided for applying a protective layer to the coding layer. The
supply store can advantageously be a supply roll and the receiving
store a storage roll. Advantageously, the coating station has
carrier rolls over whose roll periphery the carrier foil and the
masking foil are guided.
[0038] The method of the invention can also be carried out in such
manner that initially a layer is applied and this layer during or
after application is so magnetized that it has a homogeneous
anisotropic direction so that the layer is then:
[0039] a) subjected to a homogeneous magnetic field and a
nonhomogeneous temperature field, or
[0040] b) subjected to a nonhomogeneous magnetic field and a
homogeneous temperature field, or
[0041] c) subjected to a nonhomogeneous magnetic field and
temperature field, whereby the temperature lies above the Curie
temperature of the layer.
[0042] By heating the homogeneously magnetized layer to a
temperature above the Curie temperature of the layer. By heating
the homogeneously magnetized layer to a temperature above the Curie
temperature the distributions of the different magnetic anistropies
can be so controlled that either the temperature field under
simultaneous effect of a magnetic field is nonhomogeneously formed
whereby the magnetic field can either be homogeneous or
nonhomogeneously formed or with a homogeneous temperature field, a
nonhomogeneous magnetic field is produced.
[0043] To create the magnetic field both in the formation of the
layer and also in the subsequent temperature treatment, a
magnetizable carrier can be provided which is correspondingly
magnetized. Instead, a magnetizable underlay can also be provided
which is correspondingly homogeneously or nonhomogeneously
magnetized and the carrier with the layer can be placed on this
underlay. To the extent that a magnetic field is impressed
subsequent to the layer formation, the combination of underlay and
carrier can be exposed to the temperature field. To the extent that
the method is carried out continuously, a carrier foil should be
drawn from a supply and brought together with a continuously
displaced magnetic foil and the two fed through a heating station
after which they are again separated. The magnetic foil can also be
initially drawn from a supply and then magnetized and then
downstream of the heating station taken up in a store.
Alternatively, the magnetic foil can be displaced in a closed path
through the heating station, whereby the magnetic foil is
magnetized upstream of the heating station and downstream of the
heating station is demagnetized or magnetization homogenized. The
latter is especially advantageous when the carrier foil is to be
exposed to a nonhomogeneous magnetic field. An apparatus for
carrying out your method is characterized in accordance with the
invention by
[0044] a) a supply store for a carrier foil;
[0045] b) a treatment station with a magnetization unit and a
heating unit;
[0046] c) a receiving store for taking up the marking device;
[0047] d) guide elements and a drive for feeding the carrier foil
from the supply store through the treatment station to the
receiving store.
[0048] With the aid of this apparatus a corresponding method can be
carried out in which in the treatment station a nonhomogeneous or
homogeneous magnetization and or homogeneous or nonhomogeneous heat
treatment can be effected. A prerequisite for the application of a
homogeneous ferromagnetic or ferrimagnetic layer with a homogeneous
orientation of the bidirectional anisotropy on the carrier foil.
Advantageously this can be achieved with an apparatus in which the
aforedescribed apparatus is completed with the following apparatus
parts:
[0049] a) a coating station for applying a layer with homogeneous
anistropy to the carrier foil;
[0050] b) guide elements and a drive for feeding the carrier foil
from the supply store through the coating station and the treating
station to the receiving store.
[0051] The coating station is provided with a device for producing
a sufficiently strong homogeneous magnetic field that fixes the
magnetic anisotropy. The device can be so configured that directly
above the carrier foil and between the coating station and the
carrier foil at a location at which the material meets the carrier
foil a sufficient magnetic field is created for a new orientation
of the magnetic anisotropy.
[0052] The application of a magnetic field can be effected in this
case also with the aid of a magnetic foil which is correspondingly
homogeneous or nonhomogeneous magnetized, whereby the guide
elements effect a joining of the carrier foil and the magnetic foil
upstream of the treatment station. In more concrete terms, this can
be achieved in that a supply store is provided for the magnetic
foil upstream of the treatment station and a receiving store is
provided downstream of the treatment station and the magnetizing
unit is located between the supply store and the heating
device.
[0053] Instead, the magnetic foil can also be of endless
configuration and can be fed via the guide elements together with
the carrier foil through the heating unit. To the extent that a
nonhomogeneous magnetic foil is to be produced, the magnetizing
unit can be arranged in the travel direction of the carrier foil
upstream of the heating unit and, in addition, a quenching device
can be provided for demagnetization or homogenizing the magnetic
field between the heating unit and the magnetizing unit. The
magnetic foil can be fed freely over rerouting rollers it can,
however, also be stretched over a support roll which is juxtaposed
with the treatment station. In this case, however, an additional
magnetic foil can be eliminated when the roll periphery is
magnetizable or has a magnetizable coating. The quenching device
and the magnetization device are preferably located one after the
other in the direction of rotation of the support roll in the
region of the support roll which is free from the carrier foil.
Depending upon the type of method, the treatment station can have
heating units for locally heating the carrier foil whereby lasers
are especially suitable for this purpose. In this case, a
homogeneous magnetic field is sufficient as generated by a
corresponding magnetizing unit. Alternatively, the treatment
station can have a heating device for producing a homogeneous
temperature field as well as a magnetic field for producing a
nonhomogeneous magnetic field. The alteration of a homogeneously
magnetized layer in the sense of the present invention can be
effected not only by a subsequent impression with a magnetic field
and a temperature field, but local ion bombardment in the sense
that the alteration of the direction of the anistropy and/or the
remanence will occur. The ion bombardment can be effected with the
aid of a focused ion beam. Alternatively, the ion bombardment can
be effected on an areawide basis and in the region of the carrier,
a nonhomogeneous electronic charge field can be generated.
[0054] This can be so arranged that an electrically chargeable
carrier is charged prior to the ion bombardment with a
nonhomogeneous electric charge. The electric charge can, for
example, be produced with the aid of a nonhomogeneously
electrically charged underlay on which the carrier is placed.
[0055] The carrier foil is advantageously drawn from a supply and
after the coating brought together with a continuously displaced
charging foil as an underlay. Both are then subjected to areawide
ion bombardment. Then they are again separated from one another.
The charging foil can also be drawn from a supply and then charged
and after the ion bombardment can be taken up in a store.
[0056] In a variation, the charging foil can be also circulated as
an underlay through the ion bombardment station and the charging
foil can be charged upstream of the ion bombardment station and
downstream of the ion bombardment station again discharged or can
have its electronic charge homogenized. In this manner individual
charge patterns can be applied.
[0057] Alternatively thereto it is proposed that a charging foil
and a masking foil be continuously drawn from respective supplies
and brought together and that the ion bombardment then be effected
from the side of the masking foil and the masking foil again
separated from the carrier foil. In this case, the masking foil,
after withdrawal from the supply and prior to being brought
together with the carrier foil, should be provided with cutouts. It
can also be provided that the masking foil be held in a supply
already provided with cutouts.
[0058] The apparatus can be formed analogously to the apparatus in
which a treatment station is provided with a magnetization unit and
a heating unit. Instead of this treatment station, now an ion
[0059] The apparatus can be formed analogously to the apparatus in
which a treatment station is provided with a magnetization unit and
a heating unit. Instead of this treatment station, now an ion
bombardment station is provided for the ion beam treatment of the
layer on the carrier foil. With the aid of the ion bomb station, a
focused ion beam can be generated whereby a controlled device
cooperates therewith is a targeted control of the ion beam. A
nonhomogeneous ion beam treatment can, however, be produced with an
areawide ion beam when it impinges on regions of the carrier foil
with a nonhomogeneous charge field which has a charge corresponding
to the charge of the ions and thus can repel the ion beam in these
regions so that the ions of the beam do not impinge upon the
carrier foil.
[0060] Finally, it can, for example also be effective to guide an
electrically chargeable carrier foil through the ion bombardment
station, where a charge device applies a nonhomogeneous electric
charge thereto. Alternatively, an electrically chargeable charging
foil can be passed through the ion bombardment station and can have
been provided with a nonhomogeneous electric charge, the guide
elements effecting a meeting of the carrying foil and the charging
foil upstream of the ion bombardment station. A supply store can be
provided for the carrier foil upstream of the ion bombardment
station and a receiving store downstream of the ion bombardment
station while a charging device for applying a nonhomogeneous
charge to the charging foil is arranged between the supply station.
Instead, the carrier foil can, however, be configured as an endless
charging foil and guided via the guide elements together with the
carrier foil through the ion bombardment station. In this case, the
charging device is provided in the travel direction of the carrier
foil upstream of the ion bombardment station and a quenching device
can be provided for discharging or homogenizing the electric charge
bottom the ion bombardment and the charging device. The charging
foil can also be stretched over a support roll which is juxtaposed
with the ion bombardment station.
[0061] In the latter case, a charging foil can be eliminated when
the roll periphery of the support roll is chargeable with an
electric charge. Then a charging device for charging the roll
periphery and a quenched device for discharging or homogenizing the
electric charge of the roll periphery should be provided.
[0062] To enable the roll periphery to be chargeable, it can also
be provided with a corresponding coating.
[0063] The charging device and the discharging device are
advantageous disposed one after the other in the direction of
rotation of the support roll and in a region of the support roll
which is free from the carrier foil.
[0064] As an alternative thereto, it can be provided that a masking
foil is fed through the ion bombardment station and that the guide
elements effect a meeting of the carrier foil and the masking foil
upstream of the ion bombardment station in such manner that the ion
bombardment is carried out from the side of the masking foil and
that the guide elements separate the carrier foil and masking foil
downstream of the ion bombardment station. In this case as well,
the ion bombardment can be effected on an area wide basis, whereby
the impact on the layer on the carrier foil is limited by the
cutouts in the masking foil.
[0065] In the apparatus, an already preformed masking foil can be
introduced. As an alternative thereto, it is proposed in accordance
with the invention that between a supply store for the masking foil
and the meeting of the masking foil and the carrier, a mask forming
station be arranged to produce the cutouts in the masking foil,
whereby the masking forming station is provided as a laser burning
unit with a control device for varying the position control of the
laser burning unit.
[0066] The subject of the invention is also a method of reading the
above described marking devices with the aid of at least one
magnetic field sensor.
[0067] According to the invention, the coding is subjected to at
least two reading processes whereby one reading process is effected
in a zero field and one reading processing an externally applied
magnetic field or the reading processes are effected under
different magnetic fields. In the first mentioned reading process,
information stored in the magnetic regions is detected based upon
location, for example, by reading certain features of the
hysteresis loops. In the second reading process, which preferably
is carried out under saturation magnetization, the distribution of
the saturation magnetization is detected and compared with a
predetermined reference structure. The sequence of the two reading
processes does not matter.
[0068] It is also of advantage that for the reading of the marking
devices according to the invention, conventional magnetic field
sensors are suitable, that is, for example, inductive sensors,
magnetoresistive sensors, magneto-optical sensors, Hall-effect
sensors or SQUID sensors.
[0069] The reading which is resolved as to location is effected by
relative movement between the magnetic field sensor and the marking
device and it is not significant whether one or the other of the
two is moved. A plurality of magnetic sensors can also be used to
detect the magnetic structure of the marking device in a stationary
state but as a function of position.
[0070] To detect the information stored in the coating, various
features of the hysteresis loop can be considered. It is simple to
detect the remanence in a zero field or a very small magnetic
field. Instead, it is, however, also possible to detect the flux
change at the boundaries between two positions since with the
marking device according to the invention at these boundaries stray
fields arise whose distribution in a certain direction from the
coding.
[0071] The invention is described in greater detail with reference
to the drawing based upon examples. The drawing shows:
[0072] FIG. 1 a plan view on a portion of a marking device in
remanence, illustrating the hysteresis loops of two magnetic
regions;
[0073] FIG. 2 a longitudinal section through the marking device
according to FIG. 1;
[0074] FIG. 3 a diagram illustrating the principles of the marking
device according to FIGS. 1 and 2 with a magnetic field sensor;
[0075] FIG. 4 an illustration of the principles for producing a
nonhomogeneous magnetic field by means of a magnetizable
underlay;
[0076] FIG. 5 an apparatus for producing a marking device by means
of layer build up in a nonhomogeneous field;
[0077] FIG. 6 an apparatus for producing a marking device by means
of inclined vapor deposition in two deposition directions;
[0078] FIG. 7 a device for producing a marking foil by means of ion
bombardment.
[0079] In FIGS. 1 and 2, a marking device 21 has been shown in
which a homogeneous ferromagnetic layer 23 is applied to a carrier
22. The ferromagnetic layer 23, for example, of FE, CO, NI, a
magnetic rare earth metal, an alloy or a ferrite itself has a
randomly arranged array of magnetic regions distributed over its
area and, for example, indicated at 24 or 25. In the production of
the ferromagnetic layer 23 by corresponding local field application
a magnetic anisotropy is so generated that in the magnetic regions
24, 25 the easy access is oriented corresponding to the arrows (in
FIG. 2 symbolized by the point in the circle).
[0080] If a measurement is carried out by means of a magnetic field
sensor in the direction indicated by the arrow below the carrier 22
(FIG. 2), i.e. the reading direction, the magnetic regions 24 have
a magnetic characteristic corresponding to the hysteresis loop 26
while the magnetic regions 25 have a magnetic property
corresponding to the hysteresis loops 27. At the transitions
between two enabling regions 24 and 25, there is a difference in
the strengths of the remanent magnetizations with respect to a
reading direction. The flux change there produces stray fields
which, like the local magnetization itself has a structure
affecting the signal pattern which corresponds to the coding.
[0081] By imposing an external magnetic field in the saturation
range, in the directions of the magnetic field H a uniform
magnetization arises. Upon removal of the magnetic field, the
illustrated structure returns.
[0082] In FIG. 3, the marking device 21 has been turned so that the
carrier 22 is disposed at the upper side and the ferromagnetic
layer 23 on the lower side. Below it, a magnetic field sensor 31 is
arranged which has a reading head 32 over which the marking device
21 with the carrier 22 is displaced past in the pull through
direction. At the boundaries of the different magnetized regions in
the zero field, a stray field is generated which induces a current
pulse 33. Via an external current source 34 an additional current
can be fed to a coil 35 at the reading head 32 whereby at the
location of the detection an external magnetic field is detected.
By the readout, a signal develops which is processes in an
amplification stage 37 and in a further stage 38. If the external
current is equal to zero then the stored information can be read.
If the current is sufficient to saturate the ferromagnetic layer
23, the current pulse 33 disappears. In this manner a verification
test of the coding is possible.
[0083] It is especially advantageous for the magnetic field sensor
31 and the ferromagnetic layer 23 to match each other in shape so
that the saturation field corresponds to a field stretch in which
the characteristic lines of the magnetic field sensor 31 are linear
to enable a distinction between saturation of the coding and
saturation of the magnetic field sensor. A further possibility is
overcoming the saturation problem of several magnetic field
sensors, for example, inductive or magneto-resistive magnetic field
sensors is for the saturation field to be applied in a direction
which does correspond to the sensitive region of the magnetic field
sensor. It is also advantageous to use a magnetic field sensor
which is suitable for detection of the local magnetization of the
layer, for example (a magneto-optical detection device) to exclude
influence on the external field on the sensitivity of the magnetic
field sensor.
[0084] FIG. 4 shows a carrier plate 41 on which a magnetic foil 42
is placed. The magnetic foil 42 is magnetized perpendicularly to
the layer plane in strips--for example indicated at 43--and indeed
in a strip 43 with a preferred direction downwardly and an adjacent
strip 43 with a preferred direction upwardly as symbolized by the
arrows. This yields a stray field configuration as shown
schematically by the semicircles 44. The so-configured stray field
is sufficient to localize the direction of the magnetic
anisotropy.
[0085] On the magnetic foil 42 a carrier foil 45 is placed and in
which, by means of the magnetic foil 42, a magnetic field
distribution is produced whose components in the layer plane vary
in accordance with the pattern therebelow which has been indicated
by the horizontal arrows on the carrier foil 45. By the vapor
deposition of a suitable ferromagnetic material or ferrimagnetic
material on the carrier foil 45, the magnetic field distribution
determines the spatial distribution of the magnetic anisotropy and
thus the signature of the coding.
[0086] FIG. 5 shows an apparatus 46 in which the principle of FIG.
4 is used in a continuous manufacturing process. The apparatus 46
is disposed in a housing not either shown in detail and which is
under high vacuum.
[0087] The apparatus 46 has two vapor deposition stations 47 and
48, whereby each vapor deposition station 47, 48 has a support roll
49, 50 associated therewith and which are flanked by respective
rerouting rollers 51, 52 or 53, 54 in their lower regions.
[0088] The first vapor deposition station 47 is provided above the
respective support roll 49 with a vapor deposition device 55. The
support roll 49 is provided with a magnetic layer along its roll
periphery, for example, a thin polymer layer of about 3 mm, in
which a high proportion of ferromagnetic particles are embedded.
Below the support roll 49 and between the associated rerouting
rolls 51, 52, at the left side a magnetizing unit 59 is provided
which can have a row of permanent magnets and/or magnetic field
generating coils and which is capable of providing the magnetic
layer 58 with a certain magnetization pattern which in its simplest
form can have the form shown in FIG. 4. The magnetic layer 58
produces a nonhomogeneous magnetic field corresponding to its
magnetization. To the right adjacent the magnetizing unit 59, a
quenching unit 60 is arranged which either completely demagnetizes
the magnetic layer 58 or magnetizes it homogeneously and thus
eliminates the nonhomogeneous magnetization impressed by the
magnetizing unit 59. On a supply roll 61, a carrier foil 62, for
example, a polyester foil, is rolled up. In operation, the carrier
foil 62, by the drive of the support rolls 49, 50, is withdrawn
from the supply roll 61 and pass around the first rerouting roller
51 and onto the magnetic layer 58 where it is entrained by the
rotation of the support roll 59 therewith. In the vapor deposition
unit 55, the carrier foil 62 is provided with a layer 63 of
ferromagnetic material. Through the spatial magnetic field
distribution, created by the magnetic layer 58, the desired
directional distribution of the magnetic anisotropy is
produced.
[0089] After passing around the rerouting rollers 52, 53, the
carrier foil 62 passes through the second vapor deposition station
48 where it travels onto the periphery of the respective support
roll 50 and travels with the support roll 50. It thus passes the
vapor deposition device 64 which applies a protective layer 65 over
the entire area, for example, of DLC. After traversing the second
vapor deposition station 28, the carrier foil passes around the
last rerouting roller 54 and is taken up by a storage roll 66. It
can then be subsequently subdivided into individual sheets.
[0090] With the apparatus 71 according to FIG. 6, another
manufacturing process is used. The apparatus 71 has three vapor
deposition stations 72, 73, 74, whereby the vapor deposition
stations 72, 73, 74 have support rolls 75, 76, 77 associated with
them and which, in their lower regions, are flanked by rerouting
rollers 78, 79 or 80, 81 or 82, 83. Above the support rolls 75, 76,
77, respective vapor deposition devices 84, 85, 86 are
arranged.
[0091] Upstream of the first support roll 75 there is located a
supply roll 88 on which a carrier foil 89 is rolled. Above the
supply roll 88, a further supply roll 90 is provided on which a
making foil 91 is provided.
[0092] The further supply roll 90 is juxtaposed with a roll 92 with
the aid of which opens, for example, indicated at 93 can be burned
into the masking foil 91.
[0093] Upstream of the second support roll 76 there is found a
third supply roll 94 on which a second masking foil 95 is rolled.
The third supply roll 94 is also here juxtaposed with a laser
device 96 with openings, for example, designated with 97 are burned
out of the masking foil 95.
[0094] In operation, the carrier foil 89 and the masking foils 91,
95 are drawn at the same speed from their supply rolls 88 or 90 or
94, for example by the drive of the support rolls 75, 76, 77. In
the masking foils 91, 95 shortly downstream of their respective
supply rolls 90 or 94, a pattern of cutouts 93, 99 is burned with
the aid of the laser devices 92, 96. By corresponding control of
the laser beams generated by the laser devices 92, 96, more can
also be provided--, predetermined patterns or continuously changing
random patterns, for example, made with the aid of a random
generator, can be produced, which are in a complimentary
relationship as further detailed below.
[0095] The carrier foil 89 and the masking foil 91 travel onto the
first rerouting roller 78 together and are entrained by the support
roll 75.
[0096] The masking foil 91 lies outside of the carrier foil 89.
Both are based together in the upper region of the support roll 75
past the first vapor deposition device 84 whereby the vapor
deposition device vapor deposits a ferromagnetic layer 98 in a
first direction with the deposit however appearing only in the
regions of the cutouts 93 on the carrier foil 89. After passing
around the rerouting roller 79, the masking foil 91 is led upwardly
away from the carrier foil 89 and rolled up on a storage roll
99.
[0097] The carrier foil 89 then travels horizontally to the next
rerouting roller 80 and combines their with the second masking foil
95. Both then travel on the support roll 76. With the aid of the
vapor deposition unit 85, a second ferromagnetic layer 100 is vapor
deposited on the carrier foil 89 with a second direction different
from the first. This deposition on the carrier foil 89 is also
delimited to the regions of the cutouts 97. The cutouts 97 are so
arranged that they leave on the carrier foil 89 only regions free
which are covered in the first coating station by the masking foil
91 there. Because of the different vapor deposition directions of
the vapor deposition devices 84 and 85, regions are produced with
different directions of the easy axis of magnetic anistropy.
[0098] Next, the thus coated carrier foil 89 loops around the
rerouting rollers 81, 82 and passes into the last support roll 77.
With the aid of the further deposition unit 86, a protective layer
103 is applies to the ferromagnetic coding layer 102. After passing
the last rerouting roller 83 the carrier provider 89 with the
coating is rolled up on a storage roll 103. It can then be
correspondingly packaged depending upon its respective use.
[0099] FIG. 7 shows a further apparatus 111 for the production of a
marking device with regional anisotropy. It has, in the sequence of
travel, a first vapor deposition station 112, an ion bombardment
113 and a second vapor deposition station 114. The stations 112,
113, 114 are associated with support rolls 115, 116, 117 which are
flanked in their lower regions respectively by two rerouting 118,
119 or 120, 121 or 122, 123.
[0100] The vapor deposition stations 112, 114 are each provided
with a vapor deposition device 124, 125 above the associated
support roll 115, 117. In the ion bombardment station 113, above
the associated support roll 116 an ion bombardment device 117 is
arranged. Below the support roll 116 and between the rerouting
rollers 120, 121 associated therewith is a charging distribution
device 128 deposited at the left side and with which the support
roll 116 is provided with regions with positive charge and/or
regions of negative charge. This can be effected, for example, in
accordance with the principles of the laser printer. For this
purpose, the support roll 116 is provided with an electrically
chargeable coating 129. To the right of the charge distributing
device 128, a quenching device 130 is arranged which either
completely discharges the surface of the support roll 116 or
provides it with a homogeneous electric charge.
[0101] On a supply roll 131, a carrier foil 132 is rolled. In
operation, the carrier foil 132, for example by driving the support
rolls 115, 116, 117, is drawn from the supply roll 131, passes
around the first rerouting roller 118 and passes onto the periphery
of the first support roll 115 with which it is entrained. The
carrier foil is thereby displaced past the first vapor deposition
device 124 and is provided, by sputtering under a homogeneous
magnetized field, with a ferromagnetic layer 133. With this layer
133, the carrier foil travels around the next following rerouting
rollers 119, 120 and onto the periphery of the second support roll
116 and loops about the latter. Thus the carrier foil travels past
the ion bombardment device 127 which fires onto the layer 133 over
the entire width of the carrier foil 132. Because of the charge
distribution on the surface of the support roll 116, which was
produced previously by the charge drawbacks device 128, there are
formed on the surface of the first layer 133, regions which are
repellant for the ions of the ion bombardment device 127 and
regions with attractive potential. In the regions with attractive
potential, the layer 133 is so influenced that the magnetic
anisotropy is altered in its direction so that a coding layer 134
results.
[0102] The support roll 116, on each pass has its charge
homogenized by the quenching device 130, that is either completely
discharged or provided with a homogeneous charge, at each pass
upstream of the charge distribution device 128 so that the charge
distribution device 128 always produces a new randomly generated
distribution charge pattern on the support roll 116.
[0103] After looping around the rerouting rollers 121, 122, the
carrier foil 132 travels into the second vapor deposition station
114 where its here guided again over the periphery of a support
roll 117. There the layer 133 receives, with the aid of the vapor
deposition device 125 and over its entire area, a protective layer
135.
[0104] The carrier foil 132 then travels around the last rerouting
roller 123 and is rolled up in a storage roll 136. It can be
subsequently subdivided.
[0105] It will be understood that in FIGS. 6 and 7 as well devices
71, 111 can be disposed within a housing which is under high
vacuum.
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