Note: Descriptions are shown in the official language in which they were submitted.
W09S/14944 21 7736& r~ M
V~ N OF ~;UUI~r;H~ T.F';,
This invention relates to a means of invisibly marking articles for
identification and authentication purposes, particularly (but not
exclusively) in the retail trade,
The counterfeiting and parallel trading of retail goods is a long standing
problem in the retail industry: lost revenue, legal liability for claims
and ~uaL~lL~es~ and damage to goodwill can seriously affect a company.
The need for an effective means of combating counterfeiting has been the
subject of considerable effort in the past. Perhaps the simplest and most
common way of in~lirPtin~ the origin of goods is by the use of trade marks.
Such marks, which are directed primarily at the customer. are obvious to
the counterfeiter and readily lend themselves to copying. As a
COUnL~L~ UL~ some marks have become increasingly complex in design,
sometimes incorporating sophisticated optical effects such as holograms,
diffraction effects etc., but the determined counterfeiter has proved equal
to the task of copying even the most sophisticated mark.
The use of infrared technology in the retail trade is also known. For
example EP 444 331 describes the marking of an object with a code which can
be scanned with infrared radiation. The code is applied using a printing
ink which is colourless in the visible spectrum but absorbing in the
infrared spectrum.
The above patent is primarily concerned with use on decorative packs, where
a visible code would be undesirable, and with the prevention of
counterfeiting of banknotes. The need for infrared scanning equipment
renders the technique unsuitable for many of the circumstances which arise
in the ongoing campaign against illegal trading: often it is necessary to
enter premises and inspect the suspect goods and this is a potentially
dangerous situation for the inspector concerned. The need for a means of
covertly inspecting suspect goods is well r~cognised.
21 77368
la
Japanese patent application number Hl 305 484 is concerned with a bar coding system in
which the bar code label is constructed from inlc which absorbs infrared light and trarlsmits
visible light. The bar code is scanned using infrared light to recover data, but no image of the
label is fommed.
Similarly,JapanesepatentapplicationnumberH5274462isconcemedwith;,~ ..l,...,,1;"~a
bar code which does not spoil the extemal appearance of an article. The bar code is irLvisible
under visible light but may be scanned using an infrared beam. Again no image is fommed.
~uropean Patent Application 0 440 814 relates to the fabrication of Identity cards which r
contain data of several types irlcludmg pictorial data which is gathered using a CCD scanner.
This invention is not, however, concemed with infrared imaging.
AMENGED SHEET
2~ 77368
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According to this invention, apparatus for identifying articles~/comprises
at least one label for applying to articles and is ~ L&~L~,lsed by means
for producing an image of said label based on its optical properties in the
infrared region of the elc~LL~ Lic spectrum, said label having
charactersitics which are not visible to the unaided hu_an eye but which
are visible in the image so produced.
In a preferred: ~ ' m~nt. the infrared imaging equipment comprises a
television camera which is sensitive to radiation within the infrared
region of the ele~ LL U~ Llc spectrum .
In a further preferred ' ~mont the television camera is of the silicon
charge coupled device ~CCD) type.
In a further preferred: ' ' m~nt an optical filter is used to reduce the
amount of visible light entering the television camera.
In a further preferred Pmt~o~1im~nt the optical filter comprises a
~- ' 'n51t~nn of gelatin filters.
In a further pre~erred Pnho~im~nt the optical filter comprises crossed
polaroids .
In a further preferred: ' _''m~nt the optical filter may be switched in and
out of operation.
In a further preferred ' m~ont the optical filter comprises a liquid
crystal cell.
In a further preferred embodiment the switching of the optical filter is
synchronised to the camera frame period.
In a further preferred embodiment an artificial source of infrared
radiation is used to ill 'n~tP the article~.
AMENDED SHEET
. '
~- 21 77368
In a further preferred embodiment the source of infrared radiation
comprises an infrared radiation emitting diode.
In a further preferred rmho~lim~nt the source of infrared radiation
comprises a tungsten lamp.
In a further preferred embodiment the output from the source of infrared
radiation is not visible under normal viewing conditions.
In a further preferred ~mhorl~mrnt the source of infrared radiation F
comprises tungsten lamp used in con~unction with an optical filter.
In addition to its use as an anticounterfeiting tool, the current invention
provides a means for combating parallel tradin6. Information rnnrF~rn~ng
the legitimate retail route for an article (eg date of manufacture, batch
no., legitimate distributor or retail outlet etc. ~ may be secretly
incorporated into a label on the article. The articles may then be
examined in a retail outlet or warehouse in order to ascertain whether they
have gone through a legitimate route from the factory to that outlet.
Under the present invention an identification mark, which is not
rorn~n1cAhl~ as such under normal viewing conditions, is applied to
articles and means of visually checking articles for the presence of such
labels is provided. Unlike the invention described in the above referenced
patent, the current invention forms a visible two ~imr-ncinnAl image of the
identification mark. The images produced can be viewed on a suitable
television monitor or recorded using standard video recording equipment for
future reference. Moreover, with the benefit of current technologY, the
imaging equipment used can be small enough to be used covertly.
AMENDED SHEET
WO 95/14944 2 1 7 7 3 6 8 r~ c77
The invention will now be described, by way of example only, with reference
to the following figures in which:-
Figure l i8 a schematic repr~cPntAt;r,n of an embodiment of the invention.
Figures 2a and 2b show, by example, cross sections of identification markswhich may be used in this embodiment.
Figure 3 is a schematic cross-section of a liquid crystal cell for use as a
switchable optical filter in this embodiment.
Referring to figure l, articles or their packaging 1 are labelled with a
distinctive identii'ication mark 2 . The ~ Je.lL 0~ of this mark when viewed
with the aid of suitable IR imaging equipment is ~icrPrnih1y different to
that when viewed with the unaided eye under normal lighting conditions.
The label may if required contain coded lnformation about, for example. the
origin of the goods, date of manufacture etc. That component of' the mark
which is visible under normal lighting conditions can be incorporated into
the visible features of the article or package so that it would not be
obvious that a mark is present.
There are several means -of devising suitable marks, for example by use of
materials which are substantially transparent in the visible spectrum but
absorbing, or reflecting, in the infrared (for example a thin layer 4f
copper sulphate). The fundamental requirement is that the authentication
mark is not rrrr~niqAhlr as such to the unassisted human eye but is
rrrr.~niqAh1r- if irradiated with infrared radiation and viewed with the aid
of suitable equipment, - in this case a CCD TV camera. Other embodiments
may include some of the optical effects currently seen in the visible
spectrum (eg diffraction, hologramatic etc, see for example "Principles of
Optics" by M ~3orn and E Wolf, Pergamon Press).
.
WO95/14944 21 77 3 68 r~ i77
Articles are checked using a Pulnix model TM6 silicon CCD Al`V camera 3available from Pulnix house, Aviary court, Wade Road, Basingstoke,
Hampshire, RG24 OLP, UK. The sensitivity of this device extends from the
lower end of the visible region of the el-~Li ui,ia~jl,eLic spectrum (wavelengthof 0.4 micrometre) into the near infrared region (up to a wavelength of 1.1
micrometer) where it is limited by the bandgap of silicon. ûther imaging
devices can be used if their sensitivity extends into the infrared
spectrum .
The lens 4 used with this camera was an 8.5mm fl.3 item available from RS
components, (stock no 625-132) PO Box 99, Corby, Northants., NN17 9RS, UK.
Any standard CCTV lens, selected to give the required range, field of view
etc., and which is 1, ~ii,y~ t to infrared within the wavelength range
being used would be acceptable.
An optical filter 5 may be placed in the path of radiation entering thecamera (most conveniently over the lens) to filter out visible radiation.
In this ' ''monf an electronically switchable filter derived from
polaroids and liquid crystal material is used. Use of a switchable filter,
in con~unction with a camera sensitive to both infrared and visible
radiation allows the investigator to reference the infrared images to the
more familiar visible image of the article under scrutiny.
The infrared radiation which is present in the ambient lighting may be
s rrl torl by means such as a switchable tungsten lamp 6. Covert
ill 'n~tir~n may be achieved by including a filter 7 to block out the
visible component from the output of the lamp 6. In this embodiment,
filter 7 was cu--~L~ u~:Lt:~'i using three Wratten (TMr) gelatin filters: Nos.
25 (red), 58 (green) and 47B (blue).
WO 95/14944 P~
21 77368
Referring to figure 2a, authentication mark 2 comprises two layers. In
this example the first layer 8 comprises a material which is absorbing in
the infrared region (for exàmple copper sulphate) and is covered by the
second layer 9 which is printed in ink which is not LLal~ Lellt to all
radiation in the visible region but LLal.~l,c-ellt to infrared radiation
within the sensitivity range of the camera being used. Thus under normal
viewing conditions only the top layer may be seen, but with the aid of the
CCD TV camera the bottom layer, which may be patterned or coded, can be
imaged .
Figure 2b shows, in ~Lu~a ~Lion~ a second example of an identification
mark comprising a plurality of elements arranged in a single layer. One or
more element 10 is formêd in ink which is coloured under normal (visible)
lighting but is highly transmissive to infrared radiation. If the
substrate 12 is highly reflective in the infrared (for example paper) then
overall there is high reflectivity of infrared radiation.
One or more element 11 is formed in ink which is coloured under normal
(visible) lighting and absorbing or reflecting to infrared. The mark may
blend in with the other visible features of its environment under normal
viewing conditions but appears quite different when imaged using the CCD TV
camera.
Referring to figure 3, switchable optical filter 5, takes the form of aliquid crystal cell. The construction of such a device is well documented
(for example in Appl. Phys. Lettr. lf~, 1971, pl27.) and it's usefulness
in the present invention depends on the fact that whether in the blocking
or transmitting state with regard to visible radiation, it remains at least
partially LL~Ia~J~Lellt to infrared radiation of suitable wavelength
(radiation in the near IR is unaffected by the polaroid filters used in
such a device).
WO 9~14944 21 7 7 3 6 8 r_. ~.O L //
Two glass plates 13, held apart by spacers 14, sandwich a f`ive micrometre
layer of' twisted nematic li~uid crystal material E7 15 available from Merck
chemical co . ( formerly ~DH) . The glass plates 13 are clad on their outer
sides by polarisers 16a and 16b arranged so that their respective axes o~
rn~AriRa~ n are mutually perr.~n~ lAr, the directions of' these axes being
represented by ~ (in the plane of the page) and ~ (normal to the
plane o~ the page).
WO9~/14944 2 ~ 7 73 6~ r~ 77
The inner surfaces of the glass plates 13 are clad with electrodes which
take the form of thin layers of InSnO 17. Prior to assembly these surfaces
are treated so as to effect alignment of the liquid crystal molecules.
This could be achieved by, for example, unidirectional rubbing. The
direction of rubbing on each plate is substantially parallel with the
polarisation axis of the polariser Accor- )~tP~ with that plate.
Li6ht entering the cell substantially along the direction indicated by the
arrow 18 is polarised on passing through polariser 16a. As the light then
passes through the liquid crystal material 15, in the absence of an
electric field, the axis of polarisation is rotated by 90- thus allowing
the light to exit the cell through polariser 16b.
The presence of an electric field, applied via electrodes 17, removes this
90 rotation thus allowing no light to pass through polariser 15b.
