Title of Invention

APPARATUS AND METHOD FOR THE OPTICAL EXAMINATION OF VALUE DOCUMENTS

Abstract Disclosed is an apparatus for optically examining at least one value document (12) in a detection range (38) of the apparatus. Said apparatus comprises an illumination device (36) that is used for illuminating the value document (12) within the detection range (38) and is provided with at least one surface-emitting laser diode (50). The disclosed apparatus further comprises a control device (42) for triggering the laser diode (50) and a device (40) for detecting optical radiation from the detection range (38).
Full Text Apparatus and method for optical analysis of value documents
[001] The present invention relates to an apparatus and method for optical analysis
of value documents.
[002] Value documents are understood here to be card- or in particular sheet-
shaped objects that represent for example a monetary value or an authoriza-
tion and/or are not to be producible at will by unauthorized persons. They
therefore have features that are not easy to produce, in particular to copy,
whose presence is an indication of authenticity, i.e. production by an autho-
rized body. Important examples of such value documents are chip cards,
coupons, vouchers, checks and in particular bank notes.
[003] Value documents are often analyzed optically for recognition of their type
and/or their state and/or for a check of authenticity. It is fundamentally possi-
ble to use ambient light for the analysis, but such analyses show excessive
errors due to fluctuations in the properties of the ambient light.
[004] Analysis is therefore done using apparatuses that possess an illumination de-
vice for illuminating with optical radiation of given properties at least a part
of a value document portion determined by a recording area of the apparatus,
and a detection device for detecting optical radiation coming from the
recording area, in particular a value document illuminated by the illumina-
tion device.
[005] Although it is possible to use light sources such as halogen lamps for illumi-
nation, they consume a lot of power compared with the radiated power emit-
ted in a desired spectral range and therefore require adequate cooling. They
further have the disadvantage of not having a very long life. Furthermore,
such light sources have considerable space requirements.
[006] The present invention is therefore based on the problem of providing an ap-
paratus for optical analysis of value documents that permits good illumina-
tion of a value document to be analyzed while having a compact structure, as
well as of specifying a corresponding method.

[007] This problem is solved by an apparatus for optical analysis of at least one
value document in a recording area of the apparatus, having an illumination
device for illuminating the value document in at least a part of the recording
area and possessing at least one surface emitting laser diode, and a control
device for driving the laser diode, and a detection device for recording opti-
cal radiation from at least a part of the recording area.
[008] The problem is further solved by a method for optical analysis of a value
document in a recording area wherein the value document is illuminated with
at least one surface emitting laser diode.
[009] In the method it is possible to preferably record optical radiation from at
least a part of the recording area that occurs through the illumination of the
value document. This can be in particular luminescence radiation excited in
the value document, optical radiation reflected by the value document or
transmitted therethrough.
[0010] The detection device can accordingly be disposed relative to the illumination
device and the recording area in particular in such a way that its radiation en-
try is located on the same side of the value document where it is illuminated,
or on the opposite side. This means that the detection device can be so dis-
posed that analysis is possible with incident or transmitted light or in reflec-
tion or transmission.
[0011] The analysis can fundamentally be done when the value document is at rest
relative to the analysis apparatus and in particular to the illumination device.
However, in particular upon use in a value document processing apparatus in
which value documents are analyzed automatically in succession, the value
document can also be moving during illumination. The subject matter of the
invention is therefore also an apparatus for processing value documents,
hereinafter also referred to as a value document processing apparatus, having
an inventive analysis apparatus and a transport device for moving a value
document through the recording area at a given transport speed. The trans-
port speed can be given in particular in dependence on properties of the anal-

ysis apparatus or of the transport device. Upon sequential detection it is thus
possible to obtain an image of the value document portion moving through
the recording area.
[0012] The invention departs completely from the conventional manners of illumi-
nation. Although it is possible to use conventional edge emitting laser diodes
instead of halogen lamps for illumination, they radiate optical radiation with
a very inhomogeneous and not simply symmetric intensity distribution. This
can impair the analysis of the value document.
[0013] According to the invention, a surface emitting laser diode is used for illumi-
nation. A surface emitting laser diode is understood in the context of the
present invention more precisely to be a vertical surface emitting laser diode
or in particular a semiconductor device also referred to in English as a "verti-
cal cavity surface emitting laser" (VCSEL), whose laser resonator is aligned
with its output direction, in which radiation is to be coupled out of the laser
resonator, at least approximately perpendicular to the surface of the device or
chip. In particular, the laser resonator of such surface emitting laser diodes
can have reflection devices, for example reflecting layers or reflecting layer
systems, extending at least approximately parallel to the surface.
[0014] Surprisingly, the use of such surface emitting laser diodes offers not one but
several advantages for use in an apparatus for analyzing value documents,
also referred to hereinafter as an analysis apparatus.
[0015] Further, they can be produced with large exit windows compared with edge
emitting laser diodes, so that the radiated beam is not, or hardly, influenced
by diffraction on the edges.
[0016] Furthermore, surface emitting laser diodes have a beam profile that is rota-
tionally symmetric in good approximation, which substantially facilitates a
beam shaping with simple optical elements compared to edge emitting laser
diodes.

[0017] Further, in surface emitting laser diodes the emission wavelength range is
determined more strongly by the laser resonator than in edge emitting laser
diodes. This allows narrower emission wavelength ranges and leads to higher
thermal stability of the emission wavelength range.
[0018] The full width at half maximum (FWHM) of the emission spectrum is
preferably less than 1 nm.
[0019] Also, the spatial coherence of the emitted radiation is lower than in edge
emitting laser diodes, so that speckle patterns can be largely or completely
avoided on a value document illuminated with the laser diode.
[0020] Due to the favorable beam shape of the surface emitting laser diodes, they
can be advantageously combined with each other for illumination purposes,
so that besides the laser diode at least one further surface emitting laser
diode is used for illumination in the method. It is therefore preferred in the
analysis apparatus that the illumination device possesses at least one further
surface emitting laser diode for producing a given illumination pattern in the
recording area, and the control device is configured to drive the further laser
diode.
[0021] In this case it is particularly preferable that the laser diodes are configured in
a component or chip. Such a configuration is readily possible only with sur-
face emitting laser diodes and has the advantage that it is easy to produce a
large array of laser diodes. A further advantage is that only one component
needs to be handled as the radiation source upon assembly of the analysis ap-
paratus, which substantially simplifies production.
[0022] Particularly preferably, more than 50 laser diodes are disposed on a compo-
nent.
[0023] The drive of the laser diodes by means of the control device can be effected
in different ways. In the simplest variant, all laser diodes of the illumination
device are driven jointly, so that the illumination pattern obtained in the

recording area is determined substantially by the number and arrangement of
the laser diodes.
[0024] According to another embodiment, the illumination device has at least two
groups of surface emitting laser diodes which comprise the above-mentioned
surface emitting laser diodes, and the laser diodes of one group are drivable
independently of those of the other group. The control device is configured
to drive one group of laser diodes separately from the drive of the other
groups of laser diodes. In the method the value document can then be illumi-
nated with at least two groups of surface emitting laser diodes which contain
the laser diode, the laser diodes of one group being driven separately from
those of the other group. Thus, drive of the groups permits in particular a
temporal and spatial variation of the illumination pattern, which offers the
advantage of greater variability of the illumination. A separate or indepen-
dent drive or drivability is understood here to mean that the laser diodes per-
mit such a drive. Further, the control device must be able to drive the groups
independently of each other, whereby the drive of the two groups of laser
diodes can of course be coupled, for example through a programming of the
control device.
[0025] According to a further embodiment, in the analysis apparatus the laser diodes
are drivable singly and the control device is configured to drive the laser
diodes singly. If further surface emitting laser diodes are used for illuminat-
ing the value document in the method, the laser diodes can then be driven
singly. In particular, the drive can be effected independently or separately in
the above-mentioned sense. The possibility of singly driving laser diodes on
a chip is a further advantage of surface emitting laser diodes.
[0026] The arrangement of the laser diodes and their drive permit the illumination
pattern to be largely determined in its form when only a simple illumination
optic is used, i.e. in particular an illumination optic with optical components,
such as lenses, that are rotationally symmetric at least approximately around
an optical axis, optionally folded by deflecting elements, in the area of the

beam path. The use of only such an illumination optic simplifies and cheap-
ens the production of the illumination device.
[0027] An illumination device having a plurality of surface emitting laser diodes
preferably configured in a chip or component can be used advantageously for
producing an areal illumination pattern due to the form of the beam profile
of the laser diodes. For this purpose, the analysis apparatus is preferably con-
figured to illuminate a given area with an illumination pattern whose loca-
tion-dependent intensity variation over the area illuminated by the laser
diodes is smaller than 20% of the maximum intensity of the illumination pat-
tern. In the method the laser diodes can be driven in such a way that the laser
diodes illuminate a given area of the value document with an illumination
pattern whose location-dependent intensity variation over the area is smaller
than 20% of the maximum intensity of the illumination pattern. Such an illu-
mination is particularly homogeneous and thus facilitates a reliable detection
of features. The given area preferably has an extent greater than 0.5 mm2.
[0028] This homogeneity can fundamentally be obtained by using suitable optical
components or homogenization devices in the analysis apparatus. However,
the surface emitting laser diodes are preferably disposed relative to each oth-
er for illuminating a given area with an illumination pattern so that the illu-
mination pattern produced therewith has a location-dependent intensity vari-
ation over the area smaller than 20% of the maximum intensity of the illumi-
nation pattern. This makes it possible to avoid the use of special optical com-
ponents and in particular that of homogenization devices, such as diffusing
disks, diffractive optical elements or light guides, which reduce the intensity
of the emitted optical radiation. The analysis apparatus therefore particularly
preferably has no homogenization elements, such as diffusing disks, light
guides or microlens arrays, for homogenization.
[0029] The center distance between next adjacent surface emitting laser diodes of
the illumination device is for this purpose preferably smaller than 150 um.

[0030] According to a first variant, the laser diodes can be disposed in the form of a
matrix in the analysis apparatus. They can be disposed in particular on the
grid points of a rectangular or square grid. This permits a particularly simple
production of a laser diode array on a chip, in particular since in the case of a
single drivability of the laser diodes the corresponding signal connections
can be simply designed. Furthermore, a particularly simple drive can be ef-
fected with this arrangement.
[0031] In a second variant of the analysis apparatus, the laser diodes are disposed on
the points of a hexagonal point grid. This arrangement has the advantage that
a particularly dense arrangement of the laser diodes is obtained in a simple
manner, thereby permitting a particularly homogeneous illumination pattern.
[0032] As stated above, the illumination pattern can be determined in the recording
area or on the value document at least in its form substantially by the ar-
rangement of the radiating laser diodes. In the analysis apparatus the control
device is therefore preferably configured to drive only some of the laser
diodes in each case to emit optical radiation to produce a given illumination
pattern. Accordingly, in the method the laser diodes are preferably driven to
emit optical radiation so that a given illumination pattern is produced. This
embodiment has the advantage that, depending on the configuration, a
change of the illumination pattern requires only a change of the control de-
vice. If the latter is programmable, as is preferred, it is even only necessary
to change the program.
[0033] Higher flexibility is obtained when, in a preferred embodiment of the analy-
sis apparatus, the control device is configured to drive the laser diodes in de-
pendence on a signal or data stored in the control device in such a way that
the same illumination pattern is producible at different given locations in the
recording area in dependence on the signal or data. In the method the laser
diodes can then be driven in such a way in dependence on a signal or data
that the same illumination pattern is producible at one of at least two differ-
ent locations in dependence on the signal or data. The signal can be for ex-

ample read in from an external data entry terminal via an interface or trans-
mitted by a device of the value document processing apparatus containing
the analysis apparatus. The drive of the laser diodes can consist in particular
in only some of the laser diodes being switched on or off.
[0034] Thus, in a preferred embodiment of the analysis apparatus, the control device
can in particular drive the surface emitting laser diodes in such a way that an
extension of a detection area of the detection device in the transport direction
is smaller than the extension of the illumination pattern in the transport di-
rection, and the illumination pattern extends further with respect to the detec-
tion area regarded in the transport direction than contrary to the transport di-
rection. The detection area is understood here to be that portion of the
recording area from which the detection device can receive optical radiation
for detection, in particular except for scattered radiation alone. A signal or
data on the transport direction can be made available to the control device in
the above-mentioned ways, which effects the drive of the laser diodes in de-
pendence on the signal or data. This permits two things to be obtained at the
same time. Firstly, the greater extension of the illumination pattern in the
transport direction permits a greater amount of optical radiation, i.e. more
energy, to be radiated onto a given area of the value document, for example a
track with feature substances, upon an analysis, in particular a luminescence
analysis, so that the strength of the detection radiation can be increased. Sec-
ondly, the adjustment of the analysis apparatus, more precisely, of the posi-
tion of the illumination pattern relative to the detection area, can be adjusted
automatically in dependence on the transport device upon installation in the
value document processing apparatus by corresponding signals being trans-
mitted to the control device for example from a drive system of the transport
device or another device of the value document processing apparatus or be-
ing entered manually via an interface. The analysis apparatus can therefore
be designed and used as a simply configurable module.
[0035] In the embodiment just described, the drive can in particular be switchable
between two or more illumination pattern positions.

[0036] Alternatively or in combination, in the analysis apparatus the control device
can be configured to drive the laser diodes in such a way that an illumination
pattern changing in time during illumination is produced in the recording
area. In the method it is then preferred that the laser diodes are driven in such
a way that an illumination pattern changing in time during illumination is
produced. The temporal change can be in particular given, for example by a
corresponding configuration and/or programming of the control device.
[0037] The illumination pattern can be changed here in any desired way; in particu-
lar the form of the illumination pattern can be changed. However, it is pre-
ferred for many applications that the laser diodes are driven in such a way
that a given illumination pattern is moved in a given direction at a given
speed. In the analysis apparatus the control device is then configured to drive
the laser diodes in such a way that a given illumination pattern is moved in a
given direction at a given speed. The motion needs only to be effected for a
given period of time, for example until the recording area has been swept
once by the illumination pattern. Further, it is assumed that the laser diodes
are disposed suitably for producing the illumination pattern. This embodi-
ment has a number of advantages since it is usable for different purposes.
[0038] This embodiment makes it possible in particular to record a one- or two-di-
mensional image sequentially. In particular, in this case in the analysis appa-
ratus the detection device only needs to be configured to detect optical radia-
tion from the recording area integrally or only one-dimensionally in a direc-
tion perpendicular to the moving direction of the illumination pattern. Inte-
gral detection is understood here to be a detection that is non-locally resolv-
ing at a given moment. Consecutive illumination of different locations dur-
ing motion of the illumination pattern and corresponding sequential detection
thus make it possible to produce an image by assembling the data or signals
recorded at each single detection into the image.

[0039] To permit a complete illumination that is as simple as possible to produce,
the analysis apparatus can be configured in particular to produce a rectangu-
lar, in particular linear, illumination pattern.
[0040] The analysis apparatus can be used in particular for recording one- or two-di-
mensional bar codes through motion of the illumination pattern.
[0041] The value document can fundamentally be at rest during recording. Howev-
er, for faster analysis of a large number of value documents with only one
analysis apparatus, it is preferred in the method that the value document is
moved in a given transport direction and at a given transport speed during il-
lumination.
[0042] The motion speed of the illumination pattern can fundamentally be different
from the transport speed.
[0043] However, in the method the value document is preferably moved in a trans-
port direction at a transport speed, the direction being the transport direction
and the speed being the transport speed. In a particularly preferred embodi-
ment of the processing apparatus for processing value documents, the trans-
port device is then configured to move a value document through the record-
ing area at a given transport speed, and the control device is configured to
drive the laser diode in such a way that the illumination pattern is moved in
the transport direction at the transport speed. This embodiment makes it pos-
sible in a particularly advantageous manner for an area of the analyzed value
document, in particular an optical security feature, to be followed during de-
tection, so that analysis is possible even at very high transport speeds.
[0044] In general, but in particular also in connection with the last described em-
bodiment, it is possible in the analysis apparatus that the control device is
configured to produce an illumination pattern in a given part of the recording
area in dependence on position signals from a position detection device. In
the method it is accordingly preferred that the laser diodes are driven in such
a way that an illumination pattern is produced in a given part of the recording

area in dependence on position signals from a position detection device. This
embodiment has the advantage that a device for determining the position of a
value document or the position of a feature to be analyzed optically can be
used to produce the position signal representing the position, in particular
relative to the analysis apparatus, and that precisely this feature can be illu-
minated and analyzed in dependence on said position signal. This permits the
amount of data arising upon an analysis of the total value document to be
strongly reduced, so that an analysis can be effected faster and an evaluation
device for evaluating the detection results can be constructed more simply. In
particular in the case that the detection device is configured for locally re-
solved recording of optical radiation in at least one given spectral range, a
considerable data reduction and an increase in data processing speed can be
obtained when following the feature.
[0045] Alternatively to, or in combination with, the previously described embodi-
ments, in the analysis apparatus the detection device can be configured for
locally resolved recording of optical radiation in at least one given spectral
range, and the control device configured to drive the laser diodes in such a
way that a variation of a sensitivity of the detection device to the optical radi-
ation in the spectral range is at least partly compensated in dependence on
the location. In the method it is accordingly preferred that the laser diodes
are driven in such a way that a variation of a sensitivity of a detection device
for locally resolved recording of optical radiation in at least one given spec-
tral range is at least partly compensated in dependence on the location. In
this way a local adaptation of the illuminance to the sensitivity of the detec-
tion device can be effected, even after a relatively long time, thereby permit-
ting an exact optical analysis lastingly.
[0046] Within the scope of the invention the laser diodes can be operated as contin-
uously luminous or pulsed radiation sources, for which the control device is
then configured accordingly.

[0047J The invention will hereinafter be explained more closely by way of example
with reference to the drawings. These show:
Fig. 1 a schematic representation of a value document processing apparatus ac-
cording to a first preferred embodiment;
Fig. 2 a schematic representation of an analysis apparatus of the value document
processing apparatus in Fig. 1,
Fig. 3 a schematic plan view of an edge emitting laser diode,
Fig. 4 a schematic representation of a beam profile of the edge emitting laser diode
in Fig. 3 in the form of a contour diagram,
Fig. 5 a schematic lateral sectional view of a surface emitting laser diode,
Fig. 6 a schematic representation of a beam profile of the surface emitting laser
diode in Fig. 5 in the form of a contour diagram,
Fig. 7 a schematic plan view of a chip of the analysis apparatus in Fig. 2 with a
matrix arrangement of surface emitting laser diodes,
Fig. 8 a lateral view and a plan view for two possible illuminations by drives of
the laser diodes in Fig. 7,
Fig. 9 a schematic representation of a value document processing apparatus ac-
cording to a second preferred embodiment
Fig. 10 a schematic representation of a temporal evolution of an illumination of a
value document transported in the value document processing apparatus in
Fig. 9, wherein the illumination pattern is guided after the value document,
in a lateral view and a plan view,
Fig. 11 a schematic representation of a temporal evolution of an illumination of a
value document at rest wherein the illumination pattern is guided over the
value document, in a lateral view and a plan view,

Fig. 12 a schematic representation of a part of a detection device of an analysis ap-
paratus according to a further embodiment of the invention, and
Fig. 13 a schematic plan view of a chip of the analysis apparatus in Fig. 2 with an
arrangement of surface emitting laser diodes on grid points of a hexagonal
point grid.
[0048] A value document processing apparatus 10 in Fig. 1 which comprises an ap-
paratus for optical analysis of value documents 12, in the example bank
notes, has an input pocket 14 for the input of value documents 12 to be pro-
cessed, a singler 16 which can access value documents 12 in the input pocket
14, a transport device 18 with a gate 20, and, along a transport path 22 given
by the transport device 18, an apparatus 24 for analyzing value documents
which is disposed before the gate 20, and after the gate 20 a first output
pocket 26 for value documents recognized as authentic and a second output
pocket 28 for value documents recognized as non-authentic. A central con-
trol and evaluation device 30 is connected at least to the analysis apparatus
24 and the gate 20 via signal connections and is used for driving the analysis
apparatus 24, evaluating check signals from the analysis apparatus 24 and for
driving at least the gate 20 in dependence on the result of evaluation of the
check signals.
[0049] The analysis apparatus 24 in connection with the control and evaluation de-
vice 30 is used for recording optical properties of the value documents 12
and forming check signals representing said properties.
[0050] While a value document 12 is transported past at a given transport speed in a
transport direction T given by the transport path 22, the analysis apparatus 24
records optical property values of the value document, whereby the corre-
sponding check signals are formed.
[0051] From the check signals of the analysis apparatus 24 the central control and
evaluation device 30 determines upon a check signal evaluation whether the

value document is recognized as authentic or not according to a given au-
thenticity criterion for the check signals.
[0052] The central control and evaluation device 30 has for this purpose in particu-
lar, besides corresponding interfaces for the sensors, a processor 32 and a
memory 34 connected to the processor 32 and storing at least one computer
program with program code upon the execution of which the processor 32
controls the apparatus or evaluates the check signals and drives the transport
device 18 in accordance with the evaluation.
[0053] In particular, the central control and evaluation device 30, more precisely the
processor 32 therein, can check an authenticity criterion which includes for
example reference data for a value document to be considered authentic
which are given and stored in the memory 34. In dependence on the deter-
mined authenticity or non-authenticity, the central control and evaluation de-
vice 30, in particular the processor 32 therein, drives the transport device 18,
more precisely the gate 20, in such a way that the value document 12 is
transported, according to its determined authenticity, for storage into the first
output pocket 26 for value documents recognized as authentic or into the
second storage pocket 28 for value documents recognized as non-authentic.
[0054] The analysis apparatus 24 is shown more exactly in Fig. 2. It comprises an il-
lumination device 36 for illuminating at least a part of a flat recording area
38 in the transport path 22 which is reached via the transport path 22 by val-
ue documents 12 to be analyzed, and a detection device 40. A control device
42 for driving the illumination device 36, and an evaluation device 44 for
evaluating signals from the detection device 40 are combined in a pro-
grammed data processing device 46 which in this example comprises a pro-
cessor (not shown) and a memory (not shown) which stores a program, exe-
cutable by the processor, for controlling the illumination device 36 and for
evaluating the signals from the detection device 40. The control and evalua-
tion devices 42, 44 are connected to the central control and evaluation device
30 via a signal connection.

[0055] The illumination device 36 has a semiconductor device or a semiconductor
chip 48 in which a matrix arrangement of at least fifty surface emitting laser
diodes 50 for emitting optical radiation in a given spectral range is config-
ured (cf. Fig. 7), and an illumination optic 52. The latter possesses, along an
illuminating beam path, a beam-concentrating optic 54, a deflecting element
56 for deflecting the optical radiation leaving the beam-concentrating optic
into the recording area 38, and a focusing optic 58 for focusing the deflected
illumination radiation as an illumination pattern 60 onto an illumination field
62 in the recording area 38.
[0056] The spectral range is given by the type of value documents to be analyzed,
more precisely of security features formed thereon. In this example, lumines-
cence properties of the value documents are to be analyzed. For this purpose
the spectral range is selected so that the excitation radiation for luminescence
of an authentic value document is within the spectral range. The deflecting
element 56 is deflective for the excitation radiation, but in good approxima-
tion transparent to the luminescence radiation, so that the latter can pass
through the deflecting element 56 without deflection.
[0057] Optical radiation emanating from the recording area 38 or from a value doc-
ument 12 therein, i.e. detection radiation, is imaged into infinity by the fo-
cusing optic 58 and passes through the deflecting element 56 without deflec-
tion into the detection device 40, which in the example comprises a detection
optic 64, a spectrographic device 66, for example an imaging optical grating,
illuminated by means of the detection optic 64, and detection elements 68 for
recording the intensity of spatially separated spectral components of the de-
tection radiation which are produced by the spectrographic device 66. For
transmission of detection signals representing the intensity of the impinging
spectral components to the evaluation device 44 the detection elements 68
are connected thereto via signal connections. The detection device 40 there-
fore records the detection radiation in locally unresolved fashion, so that an
integral recording of the detection radiation is given.

[0058] As illustrated in Fig. 7, the surface emitting laser diodes 50 are disposed in
the semiconductor device 48 of the illumination device 36 in parallel rows
and columns perpendicular to the rows, whereby the distance between next
adjacent laser diodes is 110 μm immediately before the particular laser
diode.
[0059] To distinguish clearly from conventional edge emitting laser diodes, Fig. 3
shows a schematic plan view of a semiconductor device 70 with an edge
emitting laser diode. The semiconductor device 70 has configured therein,
parallel to the surface of the semiconductor device 70 or of the wafer for
producing the semiconductor device, a resonator 72 which on its edges 74
and 74' along a low indexed lattice plane is partly reflective to the laser radi-
ation to be produced and in which the laser active zone, i.e. a p-n junction, of
the laser diode is located. The output laser radiation is emitted, as indicated
in Fig. 3, perpendicular to the edges 74 and 74' and parallel to the surface.
The beam profile, i.e. the intensity distribution over a plane perpendicular to
the beam direction, is shown in Fig. 4 schematically as a contour diagram in
which x and y are Cartesian coordinates in the plane and the lines represent
lines of equal intensity. One can clearly recognize a saddle shape of the dis-
tribution, which is therefore not rotationally symmetric.
[0060] Fig. 5 shows schematically, in contrast, a surface emitting laser diode 76
wherein a substrate 78 has disposed thereon a resonator 80 which is given by
reflection structures or reflecting layer structures 84, 84', for example in the
form of interference layers, extending parallel to the substrate 78 and the
wafer surface 82. The laser radiation is now emitted perpendicular to the sur-
face 82 of the wafer or the substrate 78. For simplicity's sake the electrodes
and the distribution of the current-carrying layers are not explicitly shown.
[0061] Fig. 6 shows, in a representation corresponding to Fig. 4, the beam profile of
the laser beam emitted by the surface emitting laser diode. It is in good ap-
proximation rotationally symmetric around the beam direction and is there-

fore very well suited for further beam shaping with a simple illumination op-
tic with spherical and planar optical elements as in this embodiment.
[0062] The surface emitting laser diodes 50 are configured and contacted in the
semiconductor device 48 so as to be singly drivable independently of each
other.
[0063] Number, arrangement and area of the surface emitting semiconductor diodes
50 and the illumination optic 52 are selected so that a contiguous areal illu-
mination field with a superficial extent of at least 0.5 mm2 can be illuminated
in the recording area 38 homogeneously, i.e. with an intensity fluctuation
based on the maximum intensity in the illumination area smaller than 20%.
[0064] The control device 42 is used for separately driving the laser diodes 50. In
this embodiment the analysis apparatus 24 is designed as a module to be in-
stalled in a value document processing apparatus, said module being so con-
structed that the value documents 12 are fundamentally feedable thereto from
opposite directions.
[0065] To obtain as long an illumination as possible of luminescent substances in a
value document to be analyzed, the control device 42 drives the laser diodes
50 in such a way that an illumination field 62 or an illumination pattern 60
extending further beyond a detection field 86 (cf. Fig. 8) contrary to the
transport direction T than in the transport direction T is produced in the
recording area 38. The detection field 86 is defined in that, except for scat-
tered radiation, only optical radiation from the detection field 86 can reach
the detection device 40. This achieves that an area on the value document is
exposed to the illumination or excitation radiation for a time that is longer
than the time in which it is located in the detection field 86. This permits an
increased luminescence radiation to be obtained, which facilitates the detec-
tion of the luminescence.
[0066] The control device 42 is so adapted, here through corresponding program-
ming, that upon a signal from the central control and evaluation device 30

which represents the transport direction T with respect to the position of the
analysis apparatus 24, it drives the laser diodes 50 in such a way that one of
the two illumination patterns 60, 61 shown in Fig. 8 is produced by the laser
beams 88 in the recording area 38 in dependence on the transport direction T
or the signal representing it. They are shifted relative to the chip 48 so that
the above-described effect occurs. For this purpose, only some of the laser
diodes 50 are switched on, namely the laser diodes on the left (a)) or right
(b)) in Fig. 8, while the others remain switched off. The figure does not show
the illumination optic 52 or its influence on the beam path for simplicity's
sake. "Switched on" is understood here to mean that they are operated either
continuously or also in pulsed fashion.
[0067] A second embodiment in Fig. 9 differs from the first embodiment in that
there is now disposed along the transport path 22 upstream of an analysis ap-
paratus 24' an image sensor 90 which is used for recording images of fed val-
ue documents and transfers the images to a central control and evaluation de-
vice 30' via an image signal connection. All other components are un-
changed, so that the same reference signs are used for them as in the first
embodiment and the comments on the first embodiment also apply accord-
ingly here.
[0068] The central control and evaluation device 30' differs from the central control
and evaluation device 30 in that it has an interface (not shown in Fig. 9) for
recording the image data of the image sensor 90 and is configured, in the ex-
ample through a corresponding program module, to determine from the im-
age data the position of an area of the value document, for example of a cer-
tain feature area, to be analyzed more exactly with the optical analysis appa-
ratus 24' and to output it to the analysis apparatus 24'. The image sensor 90
therefore constitutes, in conjunction with the central control and evaluation
device 30', a position detection device.
[0069] The analysis apparatus 24' differs from the analysis apparatus 24 of the first
embodiment solely in that the control device is now changed compared to the

control device 42. The control device is, more precisely, configured to drive
the laser diodes 50 differently from the control device 42. As shown
schematically in Fig. 10 in a time sequence a), b), c) in a manner correspond-
ing to Fig. 8, the control device drives the laser diodes 50 in such a way that
laser diodes 92 at the front in the transport direction are switched on and
laser diodes 94 at the back in the transport direction are switched off pro-
gressing in the transport direction T in each case in time sequence. This is ef-
fected in such a way that the same illumination pattern 60' or illumination
field 62' which is produced from laser beams 88 of the front laser diodes is
carried along directed onto the selected area 98 in the transport direction T at
the transport speed T. Thus, in effect only the selected area 98 is illuminated
while it is transported through the detection field 86. This makes it possible
to effectively reduce the production of scattered radiation or interfering radi-
ation from other areas of the value document 12.
[0070] In other embodiments the image sensor 90 can also be replaced by other de-
vices, compared to the last embodiment, that permit recognition of the posi-
tion of certain features to be analyzed. For example, it is also possible, de-
pending on the feature, to use a signal from an edge detector for recognizing
an edge of the value document leading in the transport direction, for example
a light barrier or an ultrasonic sensor, in connection with the known transport
speed and the known position of the feature on the value document to pro-
duce a suitable position signal.
[0071] A further embodiment differs from the first embodiment in that for analysis
of a value document the value document is stopped completely and after it is
stopped in the recording area a start signal is outputted to an analysis appara-
tus 24", for which purpose the central control and evaluation device 30 is
modified accordingly. The analysis apparatus 24" differs from the analysis
apparatus 24 of the first embodiment solely by the configuration or program-
ming of the control and the evaluation devices 42, 44. For all other compo-
nents the same reference signs are therefore used as in the first embodiment
and the comments thereon also apply accordingly here.

[0072] The control device is configured to drive the laser diodes 50 in such a way
that they produce an illumination pattern changing in time during illumina-
tion. More precisely, the laser diodes are driven in such a way that the same
illumination pattern 60" is moved over the value document 12 at a speed that
is constant in the example, as illustrated in Fig. 11 corresponding in repre-
sentation to Fig. 10 in a time sequence a), b), c). At the same time the reflect-
ed detection radiation is recorded at constant time intervals, in case of pulsed
drive of the laser diodes in synchronism with the pulses, by the detection de-
vice 40 and the evaluation device 44 and stored in the evaluation device 44
according to the time sequence and thus the location on the value document,
or transferred directly to the central control and evaluation device. Thus, an
image of the value document is obtained. Optionally after intermediate stor-
age in the evaluation device, the corresponding image data are transmitted to
the central control and evaluation device 30 and evaluated further there.
[0073] The illumination pattern 60" has a rectangular slot shape, as illustrated in
Fig. 11. The illumination pattern 60" is preferably so narrow that it can serve
as a "virtual" entrance slit for the detection device or the spectrographic de-
vice, which then need no longer have an entrance slit.
[0074] Such an analysis apparatus can also be used advantageously for recognizing
bar codes. In particular in this case the detection device need then only have
a detection element but not a spectrographic device.
[0075] In another variant, it is possible to provide in the detection device, instead of
only one detection element, a row of detection elements by means of which
areas in the recording or detection area are recordable in locally resolved
fashion along a row perpendicular to the moving direction of the illumination
pattern. Such an analysis apparatus can in particular also be used for record-
ing two-dimensional bar codes.
[0076] In a further embodiment, the analysis apparatus differs from the analysis ap-
paratus of the first embodiment by a different detection device 40'" as well as
a different control and evaluation device.

[0077] The detection device 40"' (cf. Fig. 12) has a field 100 with a two-dimension-
al arrangement of detection elements 102 for locally resolved detection of
optical radiation coming from the recording area 38 or the detection field 86,
as well as an imaging optic 104 for focusing the infinite beam path after the
focusing optic 58 onto the arrangement of detection elements 102. The de-
tection elements 102 can have different sensitivities to optical radiation in
the same spectral range, for example due to fluctuations during production or
to different aging.
[0078] The control device 42" is changed, i.e. configured, as opposed to the control
device 42 in such a way as to drive the laser diodes 50 according to the sensi-
tivity of the detection elements 102 in such a way that the differences in sen-
sitivity are evened out. More precisely, this means that the laser diodes 50
are driven in such a way that all detection elements 102 output the same de-
tection signals.
[0079] Errors in the imaging optic can also be compensated in this way.
[0080] The evaluation device 44" is configured to record the detection signals of the
detection elements 102.
[0081] In a particularly preferred embodiment, the control device is configured to
record the detection signals from the detection elements for a given drive of
the laser diodes by means of the evaluation device, and to automatically
change the drive of the laser diodes in such a way that all detection elements
emit the same detection signal.
[0082] This corresponds in a sense to a calibration of the analysis apparatus. This
process can, depending on the embodiment, be carried out automatically at
given intervals in the service life of the analysis apparatus or upon each
switch-on or switch-off of the analysis apparatus, for which purpose the con-
trol device can be configured accordingly, for example through correspond-
ing programming.

[0083] Yet a further embodiment differs from the first embodiment only in that the
surface emitting laser diodes 50 are configured in the semiconductor device
and contacted so as to be drivable separately or independently of each other
in at least two groups, in this embodiment row by row. The control device 42
is accordingly modified in such a way as to drive the groups, i.e. here the
rows, singly separately from each other, whereby the same illumination pat-
tern as in the first embodiment can be obtained.
[0084] Further embodiments differ from the previously described embodiments only
by the arrangement of the laser diodes 50 in the semiconductor device 48'.
All other parts are unchanged. The surface emitting laser diodes 50 are now
disposed in the semiconductor device 48' (cf. Fig. 13) on the grid points of a
hexagonal point grid at a distance of nearest neighbors smaller than 120 um,
in the example 100 jim, thereby making it possible to obtain a further in-
crease in the homogeneity of the illumination pattern.
[0085] In yet further embodiments, the illumination device does not have the de-
flecting element 56, so that a straight illuminating beam path is obtained.
The detection device is configured and disposed for detecting optical radia-
tion after transmission through the value document. It has its own optic, cor-
responding in its properties to the focusing optic, for imaging at least a por-
tion of the value document on the side not illuminated by the illumination
device.
[0086] In other embodiments, the illumination of the value document can also be ef-
fected at angles other than 90°, in which case the detection device might be
configured and disposed accordingly.

Claims
1. An apparatus for optical analysis of at least one value document (12) in a record-
ing area (38) of the apparatus, having
an illumination device (36) for illuminating the value document (12) in at least a
part of the recording area (38) and possessing at least one surface emitting laser
diode (50; 76),
a control device (42) for driving the laser diode (50; 76), and
a detection device (40; 40'") for recording optical radiation from at least a part of
the recording area (38).
2. The apparatus according to claim 1, wherein the illumination device (36) possess-
es at least one further surface emitting laser diode (50; 76) for producing a given
illumination pattern in the recording area, and the control device (42) is config-
ured to drive the further laser diode (50; 76).
3. The apparatus according to claim 2 or claim 3, wherein the laser diodes (50; 76)
are configured in a component (48) or chip.
4. The apparatus according to claim 2 or 3, wherein the illumination device (36) has
at least two groups of surface emitting laser diodes (50; 76) which comprise the
laser diodes (50; 76), wherein the laser diodes (50; 76) of one group are drivable
independently of those of the other group, and wherein the control device (42) is
configured to drive one group of laser diodes (50; 76) separately from the drive
of the other groups of laser diodes (50; 76).
5. The apparatus according to any of claims 2 to 4, wherein the laser diodes (50; 76)
are drivable singly and the control device (42) is configured to drive the laser
diodes (50; 76) singly.
6. The apparatus according to any of claims 2 to 5 which is configured to illuminate
a given area with an illumination pattern (60) whose location-dependent intensity
variation over the area illuminated by the laser diodes (50; 76) is smaller than
20% of the maximum intensity of the illumination pattern (60).

7. The apparatus according to claim 6, wherein the given area (62) has an ex-
tent greater than 0.5 mm2.
8. The apparatus according to any of claims 2 to 7, wherein the laser diodes (50; 76)
are disposed in the form of a matrix.
9. The apparatus according to any of claims 2 to 7, wherein the laser diodes (76) are
disposed on the points of a hexagonal point grid.
10. The apparatus according to any of claims 2 to 9, wherein the control device (42)
is configured to drive only some of the laser diodes (50; 76) in each case to emit
optical radiation to produce a given illumination pattern (60).
11. The apparatus according to claim 10, wherein the control device (42) is config-
ured to drive the laser diodes (50; 76) in dependence on a signal or data stored in
the control device (42) in such a way that the same illumination pattern (60) is
producible at different given locations in the recording area (38) in dependence
on the signal or data.
12. The apparatus according to claim 10 or claim 11, wherein the control device (42)
is configured to drive the laser diodes (50; 76) in such a way that an illumination
pattern (60) changing in time during illumination is produced in the recording
area (38).
13. The apparatus according to any of claims 10 to 12, wherein the control device
(42) is configured to drive the laser diodes (50; 76) in such a way that a given il-
lumination pattern (60) is moved in a given direction at a given speed.
14. The apparatus according to any of claims 2 to 13, which is configured to produce
a rectangular, in particular linear, illumination pattern (60).
15. The apparatus according to any of the previous claims, wherein the detection de-
vice (40) integrally detects optical radiation coming from the recording area (38).
16. The apparatus according to any of claims 2 to 14, wherein the detection device
(40'") is configured for locally resolved recording of optical radiation in at least

one given spectral range, and wherein the control device (42) is configured to
drive the laser diodes (50; 76) in such a way that a variation of a sensitivity of the
detection device (40'") to the optical radiation in the spectral range is compensat-
ed at least partly in dependence on the location.
17. The apparatus according to any of claims 2 to 15, wherein the control device (42)
is configured to produce an illumination pattern (60) in a given part of the record-
ing area (38) in dependence on position signals from a position detection device
(30', 90).
18. An apparatus for processing value documents (12) having an analysis apparatus
(24) according to any of the previous claims and a transport device (18) for mov-
ing a value document (12) through the recording area (38) at a given speed.
19. The apparatus for processing value documents according to claim 18, wherein the
transport device (18) is configured to move a value document (12) through the
recording area (38) at a given transport speed, and wherein the control device
(42) is configured to drive the laser diodes (50; 76) in such a way that the illumi-
nation pattern (60) is moved in the transport direction at the transport speed.
20. A method for optical analysis of a value document (12) in a recording area (38),
wherein the value document (12) is illuminated with at least one surface emitting
laser diode (50; 76).
21. The method according to claim 20, wherein the value document (12) is illuminat-
ed with at least two groups of surface emitting laser diodes (50; 76) which con-
tain the laser diode (50; 76), the laser diodes (50; 76) of one group being driven
separately from those of the other group.
22. The method according to claim 21, wherein further surface emitting laser diodes
(50; 76) are used for illuminating the value document (12), and wherein the laser
diodes (50; 76) are driven singly.
23. The method according to either of claims 21 and 22, wherein the laser diodes (50;
76) are driven in such a way that the laser diodes (50; 76) illuminate a given area

of the value document with an illumination pattern (60; 61) whose location-de-
pendent intensity variation over the area is smaller than 20% of the maximum in-
tensity of the illumination pattern.
24. The method according to any of claims 21 to 23, wherein the laser diodes (50; 76)
are driven to emit optical radiation, so that a given illumination pattern (60; 61) is
produced.
25. The method according to any of claims 21 to 24, wherein the laser diodes (50; 76)
are driven in such a way in dependence on a signal or data that the same illumina-
tion pattern (60; 61) is producible at one of at least two different locations in de-
pendence on the signal or data.
26. The method according to any of claims 21 to 25, wherein the laser diodes (50; 76)
are driven in such a way that an illumination pattern (60') changing in time during
illumination is produced.
27. The method according to any of claims 21 to 26, wherein the laser diodes (50; 76)
are driven in such a way that a given illumination pattern (60') is moved in a giv-
en direction at a given speed.
28. The method according to claim 27, wherein the value document (12) is moved in
a given transport direction and at a given transport speed during illumination.
29. The method according to claim 28, wherein the value document (12) is moved in
a transport direction at a transport speed and wherein the direction is the transport
direction and the speed is the transport speed.
30. The method according to any of claims 21 to 29, wherein the laser diodes (50; 76)
are driven in such a way that a variation of a sensitivity of a detection device
(40'") for locally resolved recording of optical radiation in at least one given
spectral range is compensated at least partly in dependence on the location.
$1. The method according to any of claims 21 to 30, wherein the laser diodes (50; 76)
are driven in such a way that an illumination pattern (60') is produced in a given

part of the recording area (38) in dependence on position signals from a position
detection device (30'; 90).

Disclosed is an apparatus for optically examining at least one value document (12) in a detection range (38) of the
apparatus. Said apparatus comprises an illumination device (36) that is used for illuminating the value document (12) within the
detection range (38) and is provided with at least one surface-emitting laser diode (50). The disclosed apparatus further comprises a
control device (42) for triggering the laser diode (50) and a device (40) for detecting optical radiation from the detection range (38).

Documents:

http://ipindiaonline.gov.in/patentsearch/GrantedSearch/viewdoc.aspx?id=oSZHjJgL6tfyuSPPysXPoA==&loc=wDBSZCsAt7zoiVrqcFJsRw==


Patent Number 268870
Indian Patent Application Number 1132/KOLNP/2009
PG Journal Number 39/2015
Publication Date 25-Sep-2015
Grant Date 21-Sep-2015
Date of Filing 24-Mar-2009
Name of Patentee GIESECKE & DEVRIENT GMBH
Applicant Address PRINZREGENTENSTR. 159, 81677 MUNCHEN
Inventors:
# Inventor's Name Inventor's Address
1 BLOSS, MICHAEL BAD ISCHLER STRASSE 2/B, 81241 MUNCHEN
2 DECKENBACH, WOLFGANG BIRKENWEG 15, 83135 SCHECHEN
3 CLARA, MARTIN KAISERSTRASSE 47, 80801 MUNCHEN
PCT International Classification Number G07D 7/12
PCT International Application Number PCT/EP2007/008383
PCT International Filing date 2007-09-26
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 10 2006 045 626.2 2006-09-27 Germany