GB2164187A - Signature validation - Google Patents

Abstract

A signature is generated by a writing implement upon a predetermined region (3) of a piece of paper, for example, which is tranversely illuminated (10) during the writing process. By monitoring (20, 21, 25) the effect of the writing implement on the illuminating beams (16, 17) the ordinate profile of the implement during the signing can be determined and the data so obtained employed to derive a transform of the signature. The region (3) may be provided by a window in a plate overlying the paper. As shown the transmitted light may be monitored; alternatively the reflected light may be monitored. <IMAGE>

Description

SPECIFICATION Signature validation This invention relates to methods and means for use in validity or recognising signature particularly for use in transaction validation/security or other applications where the identity of a person (signatory) is to be verified.

According to one aspect ofthe present invention there is provided a device for use in the analysis of a signature, comprising a region in which the signature isto be generated byawriting implement; meansfor optically illuminating said region across its surface during signature generation; means for detecting perturbation ofthis illumination by the writing imple ment; and means for deriving transform of the signature from the detecting means output.

According to another aspect of the present inven tion there is provided a method of analysing the generation of a signature comprising the transverse optical illumination ofthe region in which the signature is being generated buy a writing implement; detection ofthe perturbation ofthis illumination by the writing implement; and derivation of a transform ofthesignaturefrom signals so produced.

Embodiment of the invention will now be described with reference to the accompanying drawings, in which: Fig. 1 show a view of a signature analysis device in the "open" statefor insertion of a piece of paper upon which the signature is to be written; Fig. 2 illustrates the basic operating principle employed in a "transmission" imple entation ofthe present invention; Fig. 3 illustrates the basic operating principle employed in a "reflection" implementation ofthe present invention; Fig. 4 shows, schematically, a practical "transmis sion" implementation; Fig. 5 shows, schematically, a practical "reflection" implementation, and Fig. 6 illustrates a portion of a pen with which a signature may be written.

The signature verification methods we have pre viously proposed, such as disclosed in our Application No. 7849598 (Serial No.20391 (A. (A. E. Brewster A. J. Hicks 79-1) and our Application No. 8133884 (Serial No. 21 09970A) (A. E. Brewster-D. P Newstead-A. J. Hicks 84-5-2), are such that the act of signing generates a waveform, such as a pen velocity waveform,this being achieved electronically and involving the use of a suitably designed pen and signature tablet. The present invention, however, proposes a method and device which allows a signature to be analysed whilst being written with a substantially ordinary pen on ordinary paper, thus improving market/public acceptance.

Typicallythe paper on which the signature is to be written is sandwiched between two plates 1 and 2 (Fig.

1). The lower plate 2 provides a writing surface whilst the upper plate 1 has non-reflective surfaces and a slot orwindow3whose dimensions are such as to provide sufficientspacefora signature and may approximate to those ofthe signature space provided on current documentation, for exampletravellers cheques, credit cards, security cards etc.

The upper and lower plates may be disposed relative to each other in any fashion to permit the easy insertion of any reasonably sized paper or document upon which a signature is required and which is to be analysed for identification purposes. The exact physical format of these plates will in general be dictated by their intended use, howeverthe hinged format illustrated in Fig. 1, with a hinge 4 arranged at their long edges provides a particularly simple form of solution.

The device may be optionally equipped with a printer mechanism (not shown) capable of reproducing the signature, plus the results of its analysis as a transform ofthe signature, on other documents as desired, orwith a machine readerofa card or similar element bearing the signature ofthe holder and its transform, or its transform alone,for use in comparing signatures and/ortransformsforsignatory verifica- tion purposes. Our co-pending Application No.

(Serial No. ) (R. E. Cooke-D. P.

Newstead its.8919) describes a signature verification method involving such use of transforms of signature and, in particular, enabling signature verification to be performed at points remote from where a signature was registered and without the need to referto a central data processing or storage facility.

The operational description which follows is typical ofan unencrypted presentation of the signature generation characteristics. These, when processed, may result in an output eitherfor inclusion on a document or card atthe time of issue, orforforward transmissionovera data link, and in eithercasefor comparison with a counter signature similarly analysed in a machine designed to indicate a substantial identity or otherwise between the original and counter signature.

In the upper plate 1, typically 3/32" thick (0.238cm), is the window in which the tip of a pen is disposed for generation of a signature on a piece of paper, for example, located between plates 1 and 2. By means disposed aroundthewalls ofthewindowand examples ofwhich will be described in greater detail hereinafter, the window, or signature region, is illuminated in one or more directions parallel to and across the surface ofthe paper,that isthe window, or signature region, is illuminated transversely, the illumination being in the plane ofthe plate 1. The operation of the device is such as to detect the perturbing effect the pen has on this illumination during signature generation and from this derive a transform ofthe signature.

Fig. 2 illustrates the basic operating principle for a "transmission" type of implementation of the device.

Light from a source5 is collimated by a lens 6 to produce a parallel beam for direction across the window or signature region 3, between opposed walls ofthewindow,to a lens 7 serving to focus the beam onto a photodetector arrangement 8. When a pen is not present in the windowthe output ofthe photode tector arrangement is uniform across its whole length.

When a pen 9 is present in the window it casts a shadow at a corresponding point B between extremes A and Con the photodetector arrangement with the result that the output of the photodetector arrange ment has a corresponding dip at B as indicated.

Fig. 3 illustrates the basic operating principle for a "reflection" type of implementation ofthe device. In thistype of implementation the light inputand the light output (detector) are disposed at the same wall of the window and in factthere are a plurality of "pairs" oflightinputand outputdisposed around the window the pairs being operated in turn.When light input B disposed between extremes A and C is operated and a pen 9 is disposed in the beam obtained therefrom it can reflect the beam to the corresponding output B1 between extremes A' and C1 and thus provide a corresponding peak in the output, as indicated.

The walls of the window 3 thus define the working aperture to the signature space or region and are provided with optics pertinentto the method of illumination and detection to be employed.

Fig. 4 illustrates a practical implementation of a "transmission" type of device. By means of a single light source 10 and an optics arrangement comprising lenses 11, 12, a beam splitter 13 and reflectors 14 and 15, two substantially collimated beams 16 and 17 are obtained which can be directed from a respective one ofthe long and shortwalls ofthewindowto the opposite wall whereby to obtain complete two- dimensional illumination of the signature region. The received illumination is focussed by lens 18,19 respectively onto a respective photodiode array 20, 21 which provideyandxoutputs and thus enable a co-ordinate map ofthe signature region to be obtained.The single light source 10 may be comprised buy a laser. Alternativelytwo light sources with respective optics may be employed. Ratherthan the separate photodiode arrays 20,21 atthe outputs, a single partitioned photodiode arraytogetherwith suitableoptics can be used to detectthe outputs on both axes.

Forwriting the signature there is employed a conventional ball point pen 22, Fig. 6, oranother similarly convenient conventional pen,which has mounted at its tip a small sphere 23 from the underside of which the ink ball or pen tip 24 protrudes.

The sphere 23 provides constant response to the illuminating signal regardless ofthe inclination ofthe pen. For a "reflection" implementation the sphere is preferably highly reflective.

In the "transmission" implementation of Fig. 4, as a signature is being written, a scanning shadow is produced corresponding to each beam 1 6.and 17, the motion ofwhich shadows are detected by the corresponding photodiode arrays and processed by means indicated at 25 to yield a signature velocity transform. The illumination will preferably have chopped characteristics and a confined frequency spectrum for enabling the device to function in the face of normal levels of either natural or artificial illumination. Thechopping rate maybe ofthe order of 1 MHz, subjectto engineering considerations.

The precision of this approach will depend on the size ofthe photodiode arrays and the associated performance of the optics used. For practical purposes, however, it is envisaged that as the signature is developed itwill be described buy a minimum of 200 ordinate pairs on which processing algorithms will operate to ectractthe characteristics of signature generation. Exampled of such algorithms are de- scribed in ourApplication Nos. 7849598 and 8313884 referred to above. The processing means 25 of Fig. 4 includes ordinate storage and analysis means and has an output 26 forthe result ofthe analysis (signature transform) which can then be applied to a printer or reader as appropriate.The result ofthe analysis may be expressed in any desired form typically as a related pattern beneath or surrounding the signature.

In the "reflection" implementation of Fig. 5,the approach is based on two planar arrays 27,28 of optical fibres mounted one on top ofthe other there being a transmitting layer and a receive layer. There are the same number offibres in each layer, each fibre has an end at the window 3, and the fibres ofthe two arrays are arranged in pairs 29 sothatonefibre of a pair can act as the input and the other can act as the output as described with reference to Fig. 3. The fibres are preferably single mode fibres to preserve integrity of illumination and may ultimately be realisable in simple integrated optical form, that is they may be formed as separate waveguides in a suitable substrate.Considerations are largely the same as with the "transmission" approach, except that the fibres in the transmitting layer are sequentially illuminated to produce a scanning beam andthefibresinthe receive layer are clocked in synchronism to gain an accurate record of the motion ofthe pen. Fig. 5 illustrates the meansfor achieving this as a scanning transmission source 30 whereby light from a laser source (not shown) is applied to each transmitting fibre in turn via a fibre ribbon 31 and the fibres in the receive layer are clocked in synchronism by a scanning receiver 32 via a fibre ribbon 33. Block 34 is similarto means 25 and includes ordinate storage and analysis means with an output 35 for the result of the analysis (signature transform).A lenslet array may be employed in front of the fibre ends atthe window, for simplicity either plastics moulded lenses or holographically produced, to ensure that the scanning illumination is suitably collimated. The resolution obtainable will be governed bythe numberoffibresused.

When writing a signature light will be reflected from the pen, when it is directly in front of the fibre transmitting atthat point in time, to the corresponding receiving fibre. For all non-aligned positionsofthe pen,therefore, the receiving fibre will "see" nothing.

Given that the scan cycle rate is suitably fast compared with the generation of the signature, forexample 10KHz, accurate positional information ofthe pen will be obtained.

In principlethefibre arrays may be addressed by any of a number of techniques including mechanical deflection/distribution, passive acousto-optic deflec tion, and switched lightgatearrangements. Data will be recorded twice per cycle due to the fibre array being disposed about the full periphery of the recess, relaxing possible constraints on the manner in which the pen is held. The sphere at the top ofthe pen, in this case used as a simple reflector, provides constant reflection independent ofthe inclination of the pen.

The subject of passive deflection referred to above is described in our co-pending Application No. 8227750 (Serial No.2128355) (J. S. Heeks-R. E.Cooke37-5).

The procedures outlined above optically monitor a signature during its generation and provide data from which the neuro-physiological patterns of the signature (thetransform) can be extracted to enhance machine signature recognition capabilities. The device and method may relate to eithertransmission or reflection signature scanning, with the former offering potentially the simplest and cheapest solution, high recognition accuracy at low cost being a prerequisite forthe consumer market.

Claims (17)

1. A device for use in the analysis of a signature, comprising a region in which the signature is to be generated by a writing implement, means fo illuminating the region during signature generation, means for detecting perturbation of the illumination by the writing emplement; and means for deriving a transform ofthe signature from the detecting means output.

2. A device as claimed in claim 1 ,comprising a plate having a window thereth rough in part defining said region and within which the signature is generated, in use of the device, by the writing implement on a surfaceexposed by the window.

3. A device as claimed in claim 2, wherein the illumination means serve to direct asubstantially collimated beam across the region and in the plane of the platafrom one wall ofthewindowtothe opposite wall, andthedetecting means serve to detect the motion of the shadow cast on the opposite wall by the writing implement during signature generation.

4. Adevice as claimed in claim 3, wherein the illumination means serves also to direct another substantially collimated beam across the region and substantially at right angles to said first mentioned beam and wherein the detecting means serve also to detectthe motion of the shaetw corresponding to the other beam.

5. Adevice as claimed inclaim3including asingle light source and optical components whereby both thefirst mentioned and the other beam are derived fromthe single light source.

6. A device as claimed in claim3 or claim4, wherein the detecting means includes a respective photodiode arrayforfirst mentioned and the other beam.

7. Adevice as claimed in claim 2, wherein a plurality of light guides extend within the plateto the window, the light guides being disposed in two layers at least atthe window walls, each light guide on one layerhaving an associated lightguide in the other layer, wherein the light guides of one layer comprise means whereby light can be transmitted into the window for said illumination and the light guides of the other layer comprise means whereby light can be detected following reflection by the writing element.

8. A device as claimed in claim 7, including scanning means whereby light is transmitted from each light guide in the one layer in turn into the window and wherein said detecting means includes receiving means which scan output ends of the light guides ofthe other layer synchronously with the scanning meanswherebyto detectwhen light trans- mitted by a light guide in the one layer is received by the associated light guide in the other layer after reflection by the writing implement, thereby determining the ordinates of the region through which the implement passes during signing.

9. A device as claimed in claim 7 or claim 8, wherein said light guides are comprised of optical fibres.

10. A device as claimed in claim 9, wherein atthe windowwallthe optical fibres areterminated by collimating lenses.

11. A device as claimed in any one ofthe preceding claims in combination with a writing implement including a reflective sphere through which the writing tip of the implement protrudes.

12. A method of analysing the generation of a signature comprising illuminating a region in which the signature is being generated by a writing implement, detecting perturbation ofthe illumination by the writing implement and deriving a transform ofthe signature from signals corresponding to the detection of perturbation.

13. A method as claimed in claim 12 including the step of defining the region in which the signature is to be generated by disposing a plate having a window therein on a surface upon which the signature is to be generated by the writing implement, the signature being generated by writing with the implement on the surface via the window, the illumination being directed in the plane of the plate and across the window.

14. A method as claimed in claim 13wherein the illumination comprises a substantiallycollimated beam directed across the window from one wall ofthe window to the opposite wall and wherein the perturbation detection step comprises detecting the motion ofthe shadow cast on the opposite wall bythe writing implement during signal generation.

15. A method as claimed in claim 13 wherein the illumination further comprises another substantially collimated beam directed across the window in the plane ofthe plate and substantially at rightangNbsto said first mentioned beam, and wherein the perturba tion step comprises also detecting the motion of the shadow corresponding to the other beam.

16. A method as claimed in claim 13, wherein the plate includes a plurality of light guides extending thereintothewindow,the light guides being disposed in two layers at least at the window walls, each light guide of one layer having an associated light guide in the other layer, wherein for illuminating the region an optical beam is transmitted through each light guide in turn oftheonelayerandwhereinwhilsttheoptical beam is being transmitted through one light guide the associated light guide of the other layer is monitored whereby to detect if light is reflected thereto from the writing element.

17. A device for use in the analysis of a signature substantially as herein described with reference to and as illustrates in Figs. 1,2,4 and 6, or Figs. 1,3,5 and 6 of the accompanying drawings.

'18. A method of analysing the generation of a signature substantially as herein described with reference to Figs. 1,2,4 and 6, or Figs. 1,3,5 and 6 of the accompanying drawings.