Abstract:
A data entry device including a housing formed of at least two portions, data entry circuitry located within the housing, at least one case-open switch assembly operative to sense when the housing is opened and tamper indication circuitry operative to receive an input from the at least one case-open switch assembly and to provide an output indication of possible tampering with the data entry circuitry located within the housing, the at least one case-open switch assembly including an arrangement of electrical contacts including at least first, second and third contacts and a displaceable conductive element, the tamper indication circuitry and the third contact together being operative such that when the third contact is short circuited to at least one of the first contact, the second contact and another contact, an output indication of possible tampering is provided.

Description:
This application is a continuation of U.S. patent application Ser. No. 12/666,054, filed Aug. 1, 2011, titled SECURE POINT OF SALE TERMINAL, now U.S. Pat. No. 8,595,514, which is a U.S. National Phase Application of PCT Application No. PCT/IL2009/000724, filed Jul. 23, 2009, titled SECURE POINT OF SALE TERMINAL, which is a continuation-in-part of U.S. patent application Ser. No. 12/355,857, filed Jan. 19, 2009, titled SECURED KEYPAD DEVICES, which claims priority of U.S. Provisional Patent Application Ser. No. 61/011,993, filed Jan. 22, 2008, titled SECURED KEYPAD DEVICES, the disclosures of which are incorporated by reference. 
     REFERENCE TO RELATED APPLICATIONS 
     Reference is made to the following patent and patent applications, owned by assignee, the disclosures of which are hereby incorporated by reference, which are believed to relate to subject matter similar to the subject matter of the present application: 
     U.S. Pat. No. 6,853,093 and U.S. Published Patent Applications No. 2008/0135617 and 2007/0152042. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to secure keypad devices and more particularly to data entry devices having anti-tamper functionality. 
     BACKGROUND OF THE INVENTION 
     The following U.S. Patent Publications are believed to represent the current state of the art and are hereby incorporated by reference:
     U.S. Published Patent Application No. 2008/0278353;   U.S. Pat. Nos. 7,270,275; 6,646,565; 6,917,299 and 4,486,637;   European Patent Nos.: 1421549 and 1676182; and   Great Britain Patent Application No. GB8608277.   

     SUMMARY OF THE INVENTION 
     The present invention seeks to provide improved secure keypad devices. 
     There is thus provided in accordance with a preferred embodiment of the present invention a data entry device including a housing formed of at least two portions, data entry circuitry located within the housing, at least one case-open switch assembly operative to sense when the housing is opened and tamper indication circuitry operative to receive an input from the at least one case-open switch assembly and to provide an output indication of possible tampering with the data entry circuitry located within the housing, the at least one case-open switch assembly including an arrangement of electrical contacts including at least first, second and third contacts and a displaceable conductive element, which defines a short circuit between the first and second contacts only when the housing is closed, the third contact being arranged between the first and second contacts and the displaceable conductive element so as to normally not be short circuited to the first and second contacts when the housing is closed, the tamper indication circuitry and the third contact together being operative such that when the third contact is short circuited to at least one of the first contact, the second contact and another contact, an output indication of possible tampering is provided. 
     In accordance with a preferred embodiment of the present invention, at least one of the first contact, the second contact and another contact is connected to the tamper indication circuitry. Preferably, the first, second and third contacts are concentric. Additionally or alternatively, at least two of the first, second and third contacts are concentric rings. 
     In accordance with a preferred embodiment of the present invention, the housing includes a top housing portion including key apertures, a plurality of data entry keys are mounted in the housing to have data entry key depression travel paths in the housing, the plurality of data entry keys being associated with a substrate, which is disposed below the top housing portion and anti-tampering electrical conductors are arranged between the top housing portion and the substrate thereby to prevent unauthorized access to the substrate. 
     Preferably, the substrate is a flexible substrate. Additionally or alternatively, the anti-tampering electrical conductors are disposed peripherally of the substrate. 
     In accordance with a preferred embodiment of the present invention, the data entry device also includes a plurality of key switch contacts mounted on the substrate and arranged to be displaced into or out of electrical contact with a corresponding plurality of electrical switches by depression of corresponding ones of the plurality of data entry keys to at least a predetermined extent along corresponding ones of the data entry key depression travel paths. 
     In accordance with a preferred embodiment of the present invention, the data entry device also includes a plurality of key switch contacts mounted on the plurality of data entry keys and arranged to be displaced into or out of electrical contact with a corresponding plurality of electrical switches by depression of corresponding ones of the plurality of data entry keys to at least a predetermined extent along corresponding ones of the data entry key depression travel paths. 
     Preferably, the plurality of data entry keys are integrally formed with the substrate. 
     In accordance with a preferred embodiment of the present invention, the anti-tampering electrical conductors are electrically connected to anti-tampering detection circuitry. Additionally or alternatively, the anti-tampering electrical conductors are disposed above and below the substrate. Additionally, the anti-tampering electrical conductors above the substrate and the anti-tampering electrical conductors below the substrate are electrically connected to anti-tampering detection circuitry. Additionally or alternatively, the anti-tampering electrical conductors above the substrate are electrically connected to the anti-tampering electrical conductors below the substrate. 
     In accordance with a preferred embodiment of the present invention, the housing includes a plurality of data entry keys, the data entry keys having data entry key depression travel paths in the housing, a plurality of key switch contacts are mounted on a flexible substrate separate from the plurality of data entry keys and arranged to be displaced into or out of electrical contact with a corresponding plurality of electrical switches by depression of corresponding ones of the plurality of data entry keys to at least a predetermined extent along corresponding ones of the data entry key depression travel paths and anti-tampering electrical conductors are arranged with respect to the plurality of key switch contacts thereby to prevent unauthorized electrical contact therewith. 
     Preferably, the anti-tampering electrical conductors are disposed above and below the flexible substrate. Additionally, the anti-tampering electrical conductors above the flexible substrate and the anti-tampering electrical conductors below the flexible substrate are electrically connected to anti-tampering detection circuitry. Alternatively or additionally, the anti-tampering electrical conductors above the flexible substrate are electrically connected to the anti-tampering electrical conductors below the flexible substrate. 
     In accordance with a preferred embodiment of the present invention, the plurality of data entry keys are integrally formed with the housing. 
     There is thus provided in accordance with a preferred embodiment of the present invention a data entry device including a housing including a top housing portion including key apertures, a plurality of data entry keys mounted in the housing to have data entry key depression travel paths in the housing, the plurality of data entry keys being associated with a substrate, which is disposed below the top housing portion; and anti-tampering electrical conductors arranged between the top housing portion and the substrate thereby to prevent unauthorized access to the substrate. 
     Preferably, the substrate is a flexible substrate. In accordance with a preferred embodiment of the present invention the anti-tampering electrical conductors are disposed peripherally of the substrate. 
     In accordance with a preferred embodiment of the present invention the data entry device also includes a plurality of key switch contacts mounted on the substrate and arranged to be displaced into or out of electrical contact with a corresponding plurality of electrical switches by depression of corresponding ones of the plurality of data entry keys to at least a predetermined extent along corresponding ones of the data entry key depression travel paths. Alternatively, the data entry device includes a plurality of key switch contacts mounted on the data entry keys and arranged to be displaced into or out of electrical contact with a corresponding plurality of electrical switches by depression of corresponding ones of the plurality of data entry keys to at least a predetermined extent along corresponding ones of the data entry key depression travel paths. 
     Preferably, the plurality of data entry keys are integrally formed with the substrate. In accordance with a preferred embodiment of the present invention the anti-tampering electrical conductors are electrically connected to anti-tampering detection circuitry. 
     Preferably, the anti-tampering electrical conductors are disposed above and below the substrate. Additionally, the anti-tampering electrical conductors above the substrate and the anti-tampering electrical conductors below the substrate are electrically connected to anti-tampering detection circuitry. Additionally or alternatively, the anti-tampering electrical conductors above the substrate are electrically connected to the anti-tampering electrical conductors below the substrate. 
     There is also provided in accordance with another preferred embodiment of the present invention a data entry device including a housing element, including a plurality of data entry keys disposed therein, the data entry keys having data entry key depression travel paths in the housing element, a plurality of key switch contacts mounted on a flexible substrate separate from the plurality of data entry keys and arranged to be displaced into or out of electrical contact with a corresponding plurality of electrical switches by depression of corresponding ones of the plurality of data entry keys to at least a predetermined extent along corresponding ones of the data entry key depression travel paths and anti-tampering electrical conductors arranged with respect to the plurality of key switch contacts thereby to prevent unauthorized electrical contact therewith. 
     Preferably, the anti-tampering electrical conductors are disposed above and below the flexible substrate. Additionally, the anti-tampering electrical conductors above the flexible substrate and the anti-tampering electrical conductors below the flexible substrate are electrically connected to anti-tampering detection circuitry. Alternatively or additionally, the anti-tampering electrical conductors above the substrate are electrically connected to the anti-tampering electrical conductors below the substrate. 
     In accordance with a preferred embodiment of the present invention the plurality of data entry keys are integrally formed with the housing element. 
     There is further provided in accordance with yet another preferred embodiment of the present invention data entry device including a housing element, including a plurality of data entry keys disposed therein, a plurality of housing-open indicating switch contacts and anti-tampering electrical conductors disposed effectively surrounding the plurality of housing-open indicating switch contacts thereby to prevent unauthorized electrical contact therewith. 
     In accordance with a preferred embodiment of the present invention the anti-tampering electrical conductors are electrically connected to anti-tampering detection circuitry. 
     Preferably, the plurality of data entry keys are integrally formed with the housing element. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A and 1B  are simplified exploded view illustrations, taken in respective opposite directions, of a secure keypad device constructed and operative in accordance with a preferred embodiment of the present invention; 
         FIG. 1C  is a simplified pictorial and sectional illustration of the assembled secure keypad device of  FIGS. 1A and 1B ; 
         FIGS. 2A and 2B  are simplified exploded view illustrations, taken in respective opposite directions, of a secure keypad device constructed and operative in accordance with another preferred embodiment of the present invention; 
         FIG. 2C  is a simplified pictorial and sectional illustration of the assembled secure keypad device of  FIGS. 2A and 2B ; 
         FIG. 3  is a simplified illustration of electrical connections between anti-tampering elements in the embodiments of  FIGS. 1A-2C ; 
         FIGS. 4A and 4B  are simplified exploded view illustrations, taken in respective opposite directions, of a secure keypad device constructed and operative in accordance with a further preferred embodiment of the present invention; 
         FIG. 4C  is a simplified illustration the secure keypad device of  FIGS. 4A and 4B  at various levels of disassembly; 
         FIG. 5  is a simplified illustration of electrical connections between anti-tampering elements in the embodiments of  FIGS. 4A-4C ; 
         FIGS. 6A and 6B  are simplified exploded view illustrations, taken in respective opposite directions, of a secure keypad device constructed and operative in accordance with yet a further preferred embodiment of the present invention; 
         FIG. 7  is a simplified illustration of electrical connections between anti-tampering elements in the embodiments of  FIGS. 6A and 6B ; 
         FIG. 8  is a simplified exploded view illustration of a secure keypad device constructed and operative in accordance with a still further preferred embodiment of the present invention; 
         FIGS. 9A and 9B  are simplified sectional illustrations of part of the device of  FIG. 8 , taken along lines IX-IX in  FIG. 8 , in respective key non-depressed and key depressed operative orientations; 
         FIG. 10  is a simplified exploded view illustration of a secure keypad device constructed and operative in accordance with a yet further preferred embodiment of the present invention; 
         FIGS. 11A &amp; 11B  are simplified sectional illustrations of part of the device of  FIG. 10 , taken along lines XI-XI in  FIG. 10 , in respective key non-depressed and key depressed operative orientations; 
         FIGS. 12A and 12B  are simplified exploded view illustrations, taken in respective opposite directions, of a secure keypad device constructed and operative in accordance with still another preferred embodiment of the present invention; 
         FIG. 13A  is a simplified partially sectional, partially schematic illustration of a first embodiment of a case open switch in a closed operative orientation; 
         FIG. 13B  is a simplified sectional illustration of the first embodiment of a case open switch of  FIG. 13A  in an open operative orientation; and 
         FIG. 14A  is a simplified partially sectional, partially schematic illustration of a second embodiment of a case open switch in a closed operative orientation; and 
         FIG. 14B  is a simplified sectional illustration of the second embodiment of a case open switch of  FIG. 14A  in an open operative orientation. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Reference is now made to  FIGS. 1A ,  1 B and  1 C, which illustrate a secure keypad device constructed and operative in accordance with a preferred embodiment of the present invention. 
     As seen in  FIGS. 1A ,  1 B and  1 C, there is provided a secure keypad device  100  including a housing element  102  which, together with a back panel (not shown), defines a keypad device housing. Housing element  102  includes, on a top surface  104  thereof, a display aperture  106 , through which a display (not shown) may be viewed, and an array  108  of key apertures  110 . 
     A key mat  112 , preferably formed of a resilient plastic or rubber, defines a plurality of depressible keys  114 , preferably integrally formed with mat  112 , which partially extend through key apertures  110 . A flexible resilient protective partial enclosure  116 , which includes an anti-tampering grid  118 , formed of a multiplicity of interconnected anti-tampering electrical conductors, on a top surface  120  thereof and on side surfaces  122  thereof, is provided. A flexible cable  124  is coupled to grid  118 . 
     Disposed within protective partial enclosure  116 , underlying top surface  120 , is a key contact pad  130 . Key contact pad  130  is preferably a resilient, generally planar, pad formed of flexible and resilient plastic or rubber, having an array  132  of raised resilient conductive domes  134 , such as those commercially available from Snaptron, Inc. of Windsor, Colo., USA. 
     Disposed in predetermined spaced relationship with key contact pad  130  is an electrical circuit board  140 , which functions, inter alia, as a key contact board, defining a plurality of pairs of adjacent electrical contact pads  142 , each pair underlying a corresponding dome  134 , preferably made of carbon, metal or combination of carbon/metal. The arrangement of key contact pad  130  and of electrical circuit board  140  is such that depression of a key  114  by the finger of a user causes dome  134  to establish electrical contact with and between a corresponding pair of electrical contact pads  142  lying thereunder and in registration therewith. When key  114  is not depressed, no electrical contact exists between dome  134  and a pair of corresponding electrical contact pads  142  or between the adjacent pads of the pair. 
     Electrical circuit board  140  preferably includes an anti-tampering grid  144  formed of a multiplicity of interconnected anti-tampering electrical conductors. An electrical connector  146  is arranged for mating connection with flexible cable  124 . The anti-tampering grids  118  and  144  are coupled to anti-tampering detection circuitry  148 . 
     In accordance with a preferred embodiment of the present invention, case-open switches, which sense physical tampering and opening of the housing, are provided, preferably within partial enclosure  116 . In the illustrated embodiment, the case-open switches are each embodied in a raised resilient dome  150 , preferably formed of a conductor, mounted on key contact pad  130 . The domes may be discrete units or arrays, such as those commercially available from Snaptron, Inc. of Windsor, Colo., USA. Domes  150  preferably extend outwardly from the surface of key contact pad  130  to a greater extent than do domes  134 . 
     Disposed on electrical circuit board  140  underlying each of domes  150  are a corresponding number of arrays  152 , each preferably comprising a plurality of mutually concentric conductive pads, such as rings, each array underlying a corresponding dome  150 . The arrangement of key contact pad  130  and of electrical circuit board  140  is preferably such that as long as the housing is closed, domes  150  each are in electrical contact with some but not all of the plurality of mutually concentric conductive rings in each of arrays  152  underlying domes  150  and in registration therewith. 
     In accordance with a first embodiment of the invention, indicated in  FIG. 1A  as Option A, each array  152  comprises an outer ring  153 , an intermediate ring  154  and an inner ring  155 . In this embodiment, as long as the housing is closed and not tampered with, the dome  150  is in electrical contact with outer ring  153  and inner ring  155  but not with intermediate ring  154 . Dome  150  is normally in electrical contact with outer ring  153 . Preferably, dome  150  is soldered to outer ring  153 . If tampering is attempted, electrical contact is made between intermediate ring  154  and at least one of dome  150 , outer ring  153  and inner ring  155 . 
     In accordance with a second embodiment of the invention, indicated in  FIG. 1A  as Option B, each array  152  comprises an outermost ring  156 , a second to outermost ring  157 , an outer intermediate ring  158 , an inner intermediate ring  159  and an inner ring  160 . In this embodiment, as long as the housing is closed and not tampered with, the dome  150  is in electrical contact with outer intermediate ring  158  and inner ring  160  but not with any of outermost ring  156 , second to outermost ring  157  and inner intermediate ring  159 . Dome  150  is normally in electrical contact with outer intermediate ring  158 . Preferably, dome  150  is soldered to outer intermediate ring  158 . If tampering is attempted, electrical contact is made between at least one of outermost ring  156 , second to outermost ring  157  and inner intermediate ring  159  and at least one of dome  150 , outer intermediate ring  158  and inner ring  160 . 
     Reference is now made additionally to  FIGS. 13A and 13B  and to  FIGS. 14A and 14B , which are simplified partially sectional and partially schematic illustrations of respective first and second embodiments of the case open switch in respective closed and open operative orientations, coupled to case tamper detection circuitry. 
     As seen in  FIGS. 13A and 13B , electrical contact between each dome  150  and corresponding ring  155  is ensured by the provision of a pin  161 , preferably integrally formed on housing element  102 . When the housing is closed, pins  161  urge corresponding protrusions  162  in key mat  112  towards partial enclosure  116  and urge partial enclosure  116  and thus corresponding domes  150  towards ring  155  of array  152 . In an alternative embodiment, where partial enclosure  116  is not provided, when the housing is closed, pins  161  urge corresponding protrusions  162  in key mat  112  and thus corresponding domes  150  towards arrays  152 . 
     As seen in  FIG. 13A , outer ring  153  is grounded, intermediate ring  154  is coupled to a voltage VDD via a resistor R1 and inner ring  155  is coupled to a voltage VDD via a resistor R2. A voltage V2 may be measured to indicate whether the housing is open or closed, i.e. whether or not dome  150  is simultaneously in contact with both inner ring  155  and outer ring  153 . 
     When this simultaneous contact exists, V2 is zero; otherwise V2 equals VDD. An attempt to tamper with the switch by short circuiting inner ring  155  and outer ring  153  will also short circuit intermediate ring  154  and may be detected by measuring a voltage V1. During normal operation, where no tampering is detected, V1 is equal to VDD. An attempt to tamper with the case open switch causes voltage V1 to be zero. 
     As seen in  FIGS. 14A and 14B , electrical contact between each dome  150  and corresponding ring  160  is ensured by the provision of pin  161 , preferably integrally formed on housing element  102 . When the housing is closed, pins  161  urge corresponding protrusions  162  in key mat  112  towards partial enclosure  116  and urge partial enclosure  116  and thus corresponding domes  150  into electrical contact with rings  160 . In an alternative embodiment, where partial enclosure  116  is not provided, when the housing is closed, pins  161  urge corresponding protrusions  162  in key mat  112  and thus corresponding domes  150  towards rings  160 . 
     When attempted tampering occurs and the housing is opened, no electrical contact exists between domes  150  and corresponding rings  155  ( FIG. 13B ) or  160   FIG. 14B ) and a suitable alarm and/or disablement occurs. 
     As seen in  FIG. 14A , inner ring  160  is coupled to a voltage VCC via a resistor R2, inner intermediate ring  159  is coupled to voltage VCC via resistor R1, and outer intermediate ring  158  is grounded. Outermost ring  156  is grounded and second to outermost ring  157  is coupled to voltage VCC via resistor R1. 
     A voltage at tamper detection input points TD2 may be measured to indicate whether the hosing is open or closed, i.e. whether or not dome  150  is simultaneously in contact with both inner ring  160  and outer intermediate ring  158 . When this simultaneous contact exists, voltage measured at TD2 is zero; otherwise voltage measured at TD2 equals VCC. Thus, an attempt to remove of adequate pressure from the dome  150  and open the housing triggers a tamper response. 
     An attempt to tamper with the switch, for example by applying pressure to the snap dome, such as by drilling a hole in the dome or by injection of conductive glue, results in short circuiting inner ring  160  and outer intermediate ring  158  and inner intermediate ring  159  and may be detected by measuring a voltage at nTD3. During normal operation, where no tampering is detected, voltage measured at nTD3 is equal to VCC. An attempt to tamper with the case open switch causes voltage measured at nTD3 to be zero. 
     It is appreciated that the rings of array  152 , both in Option A and Option B and corresponding  FIGS. 13A &amp; 13B  and  FIGS. 14A &amp; 14B , can be of any suitable shape, such as circular or elliptical shape and are preferably concentric. 
     Disposed below electrical circuit board  140 , there is provided a peripheral protective grid element  163  which includes an anti-tampering grid  164 , preferably coupled to a flexible cable  165 , which is in turn connected to a connector  166  on electrical circuit hoard  140 . Peripheral protective grid element  163  preferably is located interiorly of the side surfaces  122  of enclosure  116 . Fixedly attached to peripheral protective grid element  163  and preferably disposed therebelow is a bottom protective grid element  168  which includes an anti-tampering grid  170 , which is coupled via contacts  172  and via a connector  174  which extends through an aperture  176  formed in peripheral grid element  163  into electrical contact with contacts  178  on electrical circuit board  140 . The anti-tampering grids  164  and  170  are coupled to anti-tampering detection circuitry  148 . 
     Reference is now made to  FIGS. 2A ,  2 B and  2 C, which illustrate a secure keypad device constructed and operative in accordance with another preferred embodiment of the present invention. 
     As seen in  FIGS. 2A-2C , there is provided a secure keypad device  200  including a housing element  202  which, together with a back panel (not shown), defines a keypad device housing. Housing element  202  includes, on a top surface  204  thereof, a display aperture  206 , through which a display (not shown) may be viewed, and an array  208  of key apertures  210 . 
     A key mat  212 , preferably formed of a resilient plastic or rubber, defines a plurality of depressible keys  214 , preferably integrally formed with mat  212 , which partially extend through key apertures  210 . A flexible resilient protective partial enclosure  216 , which includes an anti-tampering grid  218 , formed of a multiplicity of interconnected anti-tampering electrical conductors, on a top surface  220  thereof and on side surfaces  222  thereof, is provided. A flexible cable  224  is coupled to grid  218 . 
     Disposed within protective partial enclosure  216 , underlying top surface  220 , is a key contact pad  230 . Key contact pad  230  is preferably a resilient, generally planar, pad formed of flexible and resilient plastic or rubber, having an array  232  of raised resilient domes  234  having conductors  236  formed on corresponding bottom facing surfaces  238  thereof. 
     Disposed in predetermined spaced relationship with key contact pad  230  is a electrical circuit board  240 , which functions, inter alia, as a key contact board, defining a plurality of pairs of adjacent electrical contact pads  242 , each pair underlying a corresponding conductor  236 . The arrangement of key contact pad  230  and of electrical circuit board  240  is such that depression of a key  214  by the finger of a user causes conductor  236  to establish electrical contact with and between a corresponding pair of electrical contact pads  242  lying thereunder and in registration therewith. When key  214  is not depressed, no electrical contact exists between conductor  236  and a pair of corresponding electrical contact pads  242  or between the adjacent pads of the pair. 
     Electrical circuit board  240  preferably includes an anti-tampering grid  244  formed of a multiplicity of interconnected anti-tampering electrical conductors. An electrical connector  246  is arranged for mating connection with flexible cable  224 . The anti-tampering grids  218  and  214  are coupled to anti-tampering detection circuitry  248 . 
     In accordance with a preferred embodiment of the present invention, case-open switches, which sense physical tampering and opening of the housing, are also located within partial enclosure  216 . In the illustrated embodiment the case-open switches are each embodied in a raised resilient dome  250  formed on key contact pad  230  and have conductors  252  formed on an underside surface thereof. Domes  250  preferably extend outwardly from the surface of key contact pad  230  to a greater extent than do domes  234 . Alternatively, the case-open switches may be constructed and operative as described hereinabove with reference to one of the embodiments shown  FIGS. 1A ,  1 B,  13 A- 14 B. 
     Disposed on electrical circuit board  240  underlying each of domes  250  are a corresponding number of pairs of adjacent electrical contact pads  254 , each pair underlying a corresponding conductor  252 . The arrangement of key contact pad  230  and of electrical circuit board  240  is such that as long as the housing is closed, conductors  252  each are in electrical contact with and between a corresponding pair of electrical contact pads  254  lying thereunder and in registration therewith. This electrical contact is ensured by the provision of pins  256  integrally formed on housing element  202 . When the housing is closed, pins  256  urge corresponding protrusions  258  in key mat  212  towards partial enclosure  216  and urge partial enclosure  216  and thus corresponding domes  250  and the conductors  252 , on the underside surfaces thereof, into electrical contact with corresponding electrical contact pads  254 . 
     When the housing is opened, no electrical contact exists between conductor  252  and corresponding pairs of electrical contact pads  254  or between the adjacent pads of the pair of electrical contact pads  254  and a suitable alarm or disablement occurs. 
     Disposed below electrical circuit board  240 , there is provided a peripheral protective grid element  260  which includes an anti-tampering grid  262 , preferably coupled to a flexible cable  264 , which is in turn connected to a connector  266  on electrical circuit board  240 . Peripheral protective grid element  260  preferably is located interiorly of the side surfaces  222  of enclosure  216 . Fixedly attached to peripheral protective grid element  260 , and preferably disposed therebelow, is a bottom protective grid element  268  which includes an anti-tampering grid  270 , which is coupled via contacts  272  and via a connector  274 , which extends through an aperture  276  formed in peripheral grid element  260 , into electrical contact with contacts  278  on electrical circuit board  240 . The anti-tampering grids  262  and  270  are coupled to anti-tampering detection circuitry  248 . 
     In the illustrated embodiment of  FIGS. 2A ,  2 B and  2 C, there is also provided a structural peripheral enclosure element  280  which is disposed interiorly of the sides  222  of the flexible resilient protective partial enclosure  216  and which provides a peripheral seating surface  282  for electrical circuit board  240 . 
     Reference is now made to  FIG. 3 , which is a generalized illustration of the electrical connections described hereinabove and includes reference numerals corresponding to both of the above-described embodiments shown respectively in  FIGS. 1A-1C  and  2 A- 2 C. It may be appreciated from  FIG. 3  that all of the anti-tampering grids are connected to the anti-tampering circuitry which is located within the protective enclosure. 
     Reference is now made to  FIGS. 4A and 4B , which are simplified exploded view illustrations, taken in respective opposite directions, of a secure keypad device constructed and operative in accordance with a further preferred embodiment of the present invention, to  FIG. 4C , which is a simplified illustration the secure keypad device of  FIGS. 4A and 4B  at various stages of disassembly, and to  FIG. 5 , which is a simplified illustration of electrical connections between anti-tampering elements in the embodiments of  FIGS. 4A-4C .  FIG. 4C  is provided to better illustrate the various elements of the keypad device of  FIGS. 4A and 4B . 
     As seen in  FIGS. 4A-5 , there is provided a secure keypad device  400  including a housing element  402  which, together with a back panel (not shown), defines a keypad device housing. Housing element  402  includes, on a top surface  404  thereof, a display aperture  406 , through which a display (not shown) may be viewed, and an array  408  of key apertures  410 . 
     An anti-tamper board  412 , which includes an anti-tampering grid  414  formed of a multiplicity of interconnected anti-tampering electrical conductors  416 , underlies top surface  404  and is provided with key apertures  420  in registration with key apertures  410 . Fixedly and electrically coupled to anti-tamper board  412  is a peripheral anti-tamper keypad enclosure  422 , which preferably includes an anti-tampering grid  423  formed of a multiplicity of interconnected anti-tampering electrical conductors. 
     A key mat  432 , preferably formed of a resilient plastic or rubber, defines a plurality of depressible keys  434 , preferably integrally formed with mat  432 , which partially extend through key apertures  410  and  420  and have conductors  436  formed on corresponding bottom facing surfaces  438  thereof. 
     An electrical circuit board  440 , which functions, inter alia, as a key contact board, is disposed in predetermined spaced relationship with key mat  432  and defines a plurality of pairs of adjacent electrical contact pads  442 , each pair underlying a corresponding conductor  436 . The arrangement of key mat  432  and of electrical circuit board  440  is such that depression of a key  434  by the finger of a user causes conductor  436  to establish electrical contact with and between a corresponding pair of electrical contact pads  442  lying thereunder and in registration therewith. When key  434  is not depressed, no electrical contact exists between conductor  436  and a pair of corresponding electrical contact pads  442  or between the adjacent pads of the pair. 
     Circuit board  440  preferably includes an anti-tampering grid  444  formed of a multiplicity of interconnected anti-tampering electrical conductors. Fixedly coupled to circuit board  440  and an additional electrical circuit board  456  is a peripheral anti-tamper enclosure  460  which preferably includes an anti-tampering grid  461  formed of a multiplicity of interconnected anti-tampering electrical conductors. 
     Electrical connectors  446 , which extend through apertures  443  formed in peripheral anti-tamper enclosure  460 , are coupled via contacts  445  to grid  444  and arranged for mating connection through contacts  457  with an anti-tampering grid  454 , formed of a multiplicity of interconnected anti-tampering electrical conductors, which is formed on additional electrical circuit board  456 . 
     Electrical connectors  471  extend through apertures  473  formed in peripheral anti-tamper keypad enclosure  422  and through apertures  475  formed in circuit board  440 , each underlying corresponding aperture  473 . Electrical connectors  471  are coupled via contacts  477  to anti-tampering grid  461  and arranged for mating connection through contacts  479  with anti-tampering grid  414 . 
     Electrical connectors  481 , which extend through apertures  483  formed in keymat  432 , are coupled via contacts  485  to anti-tampering grid  414  and arranged for mating connection through contacts  487  with anti-tampering grid  444 . 
     Anti-tampering grid  423  is soldered via soldering points  489  on board  422  and soldering points  491  on board  412  to anti-tampering grid  414 . 
     It is thus appreciated that the anti tampering grids  444 ,  414 ,  454 ,  423  and  461  on boards  440 ,  412  and  456  and enclosures  422  and  460 , respectively, are interconnected so as to define an anti-tampering enclosure, which is coupled to and physically encloses anti-tampering detection circuitry  493 . 
     It is appreciated that the anti-tampering grids can be interconnected in numerous ways using various types of connectors. 
     In accordance with a preferred embodiment of the present invention, case-open switches, which sense physical tampering and opening of the housing, are also located within the anti-tampering enclosure. In the illustrated embodiment, the case-open switches are each embodied in conductors  462  mounted on key mat  432  and corresponding pair of electrical contact pads  464  mounted on board  440 . Alternatively, the case-open switches may be constructed and operative as described hereinabove with reference to one of the embodiments shown  FIGS. 1A ,  1 B,  13 A- 14 B. 
     When the housing is closed, pins  465 , which extend through apertures  466  in board  412 , force conductors  462  and corresponding pair of electrical contact pads  464  into electrical contact or between the adjacent pads of the pair. When the housing is opened, pins  465  no longer force conductors  462  and corresponding pair of electrical contact pads  464  into electrical contact and as a result electrical contact no longer exists between conductors  462  and corresponding pair of electrical contact pads  464  or between the adjacent pads of the pair and a suitable alarm or disablement occurs. 
     Reference is now made  FIGS. 6A and 6B , which are simplified exploded view illustrations, taken in respective opposite directions, of a secure keypad device constructed and operative in accordance with an additional preferred embodiment of the present invention, and to  FIG. 7 , which is a simplified illustration of electrical connections between anti-tampering elements in the embodiments of  FIGS. 6A and 6B . 
     As seen in  FIGS. 6A-7 , there is provided a secure keypad device  600  including a housing element  602  which, together with a back panel (not shown), defines a keypad device housing. Housing element  602  includes, on a top surface  604  thereof, a display aperture  606 , through which a display (not shown) may be viewed, and an array  608  of key apertures  610 . 
     An anti-tamper board  612 , which includes an anti-tampering grid  614  formed of a multiplicity of interconnected anti-tampering electrical conductors  616 , underlies top surface  604  and is provided with key apertures  620  in registration with key apertures  610 . Fixedly and electrically coupled to anti-tamper board  612  is a peripheral anti-tamper keypad enclosure  622 , which preferably includes an anti-tampering grid  624  formed of a multiplicity of interconnected anti-tampering electrical conductors. 
     A key mat  632 , preferably formed of a resilient plastic or rubber, defines a plurality of depressible keys  634  which partially extend through key apertures  610  and  620 . A flexible resilient protective element  636 , preferably a resilient generally planar pad formed of flexible and resilient plastic or rubber which includes an anti-tampering grid  638  formed of a multiplicity of interconnected anti-tampering electrical conductors, is provided. An electrical cable  640  is coupled to grid  638 . 
     Disposed below element  636  is a key contact pad  642 , preferably a resilient generally planar pad formed of flexible and resilient plastic or rubber, having an array  644  of raised resilient domes  646  having conductors  648  formed on corresponding bottom facing surfaces  650  thereof. 
     An electrical circuit board  660  is disposed in predetermined spaced relationship with key mat  632  and defines a plurality of pairs of adjacent electrical contact pads  662 , each pair underlying a corresponding conductor  648 . The arrangement of key mat  632  and of electrical circuit board  660  is such that depression of a key  634  by the finger of a user causes conductor  648  to establish electrical contact with and between a corresponding pair of electrical contact pads  662  lying thereunder and in registration therewith. When key  634  is not depressed, no electrical contact exists between conductor  648  and a pair of corresponding pads  662  or between the adjacent pads of the pair. 
     Circuit board  660  preferably includes an anti-tampering grid  664 , formed of a multiplicity of interconnected anti-tampering electrical conductors. Fixedly and electrically coupled to board  660  and to an additional electrical circuit board  670  is a peripheral anti-tamper enclosure  672 , which preferably includes an anti-tampering grid  676  formed of a multiplicity of interconnected anti-tampering electrical conductors. 
     Electrical connectors  666 , which extend through apertures  667  in peripheral anti-tamper enclosure  672 , are coupled via contacts  665  to grid  664  and arranged for mating connection through contacts  669  with an anti-tampering grid  668  formed of a multiplicity of interconnected anti-tampering electrical conductors on additional electrical circuit board  670 . 
     Electrical connectors  677  extend through apertures  679  formed in peripheral anti-tamper keypad enclosure  622  and through apertures  681  formed in board  660 , each underlying corresponding aperture  679 . Electrical connectors  677  are coupled via contacts  673  to anti-tampering grid  676  and arranged for mating connection through contacts  675  with anti-tampering grid  614 . 
     Flexible electrical cable  640  is connected to a connector  683  on electrical circuit board  660 . 
     Electrical connectors  691  extend through apertures  693  formed in flexible element  636  and through apertures  695  formed in key contact pad  642  and corresponding apertures  696  formed in key mat  632 . Electrical connectors  691  are coupled via contacts  697  to anti-tampering grid  664  and arranged for mating connection through contacts  699  with an anti-tampering grid  614 . 
     Anti-tampering grid  624  is soldered to anti-tampering grid  614 . 
     It is thus appreciated that the anti tampering grids  614 ,  664 ,  668 ,  638 ,  624  and  676 , on boards  612 ,  660  and  670 , element  636  and enclosures  622  and  672 , respectively, are interconnected so as to define an anti-tampering enclosure, which is coupled to and physically encloses anti-tampering detection circuitry  674 . 
     In accordance with a preferred embodiment of the present invention, case-open switches, which sense physical tampering and opening of the housing, are also located within the anti-tampering enclosure. In the illustrated embodiment the case-open switches are each embodied in conductors  680  mounted on the bottom facing of domes  641  of key contact pad  642  and corresponding pairs of electrical contact pads  682  mounted on board  660 . Alternatively, the case-open switches may be constructed and operative as described hereinabove with reference to one of the embodiments shown  FIGS. 1A ,  1 B,  13 A- 14 B. 
     When the housing is closed, pins  684 , which extend through apertures  686  in board  612 , urge corresponding protrusions  631  on key mat  632  towards element  636  and key contact pad  642  and urge domes  641  on key contact pad  642  towards board  660  and thus force conductors  680  and pair of electrical contact pads  682  into electrical contact. When the housing is opened, pins  684  no longer force conductors  680  and pair of electrical contact pads  682  into electrical contact and as a result electrical contact no longer exists between conductors  680  and pair of electrical contact pads  682  and a suitable alarm or disablement occurs. 
     Reference is now made to  FIG. 8 , which is a simplified exploded view illustration of a secure keypad device constructed and operative in accordance with a still further preferred embodiment of the present invention, and to  FIGS. 9A &amp; 9B , which are simplified sectional illustrations of part of the device of  FIG. 8 , taken along lines IX-IX in  FIG. 8 , in respective key non-depressed and key depressed operative orientations. 
     As seen in  FIGS. 8-9B , there is provided a secure keypad device  800  including a housing element  802  which, together with a back panel (not shown), defines a keypad device housing. Housing element  802  includes, on a top surface  804  thereof, a display aperture  806 , through which a display (not shown) may be viewed, and an array  808  of key apertures  810 . 
     An anti-tamper board  812 , which includes an anti-tampering grid  814  formed of a multiplicity of interconnected anti-tampering electrical conductors, underlies top surface  804  and is provided with key apertures  820  in registration with key apertures  810 . Fixedly and electrically coupled to anti-tamper board  812  is a peripheral anti-tamper keypad enclosure  822 , which preferably includes an anti-tampering grid  824  formed of a multiplicity of interconnected anti-tampering electrical conductors. 
     A key mat  832 , preferably, formed of a resilient plastic or rubber, defines a plurality of depressible keys  834  which partially extend through key apertures  810  and  820 . Conductors  836  are formed on key mat  832 . 
     Pairs of adjacent electrical contact pads  838  are located on board  812  in registration with conductors  836  and are arranged such that when keys  834  are in a non-depressed operative orientation, such as that shown in  FIG. 9A , electrical contact exists between conductors  836  and pairs of adjacent electrical contact pads  838  lying thereover and in registration therewith and between those pairs of adjacent electrical contact pads  838 . When keys  834  are in a depressed operative orientation, such as that shown in  FIG. 9B , no electrical contact exists between conductors  836  and pairs of adjacent electrical contact pads  838  lying thereover and in registration therewith and between those pairs of adjacent electrical contact pads  838 . 
     An electrical circuit board  840  is disposed in predetermined spaced relationship with key mat  832 . Board  840  preferably includes an anti-tampering grid  844  formed of a multiplicity of interconnected anti-tampering electrical conductors. Electrical connectors  846  are coupled to grid  844  and arranged for mating connection with an anti-tampering grid  854 , formed of a multiplicity of interconnected anti-tampering electrical conductors, which is formed on an additional electrical circuit board  856 . Fixedly and electrically coupled to boards  840  and  856  is a peripheral anti-tamper enclosure  858  which preferably includes an anti-tampering grid  859 , formed of a multiplicity of interconnected anti-tampering electrical conductors. It is thus appreciated that the anti tampering grids  844 ,  854  and  859 , on boards  840  and  856  and peripheral anti-tamper enclosure  858 , respectively, are interconnected so as to define an anti-tampering enclosure, which is coupled to and physically encloses anti-tampering detection circuitry (not shown). It is also appreciated that anti tampering grids  814  and  824  on board  812  and enclosure  822  are coupled to anti-tampering circuitry (not shown) and preferably interconnected to anti tampering grids  844 ,  854  and  859  on boards  840  and  856  and enclosure  858 . 
     In accordance with a preferred embodiment of the present invention, case-open switches, which sense physical tampering and opening of the housing, are also located within the anti-tampering enclosure. In the illustrated embodiment, the case-open switches are each embodied in conductors (not shown) mounted on key mat  832  and formed on underside surface thereof, and corresponding pair of electrical pads  864  mounted on board  840 . Alternatively, the case-open switches may be constructed and operative as described hereinabove with reference to one of the embodiments shown  FIGS. 1A ,  1 B,  13 A- 14 B. 
     When the housing is closed, pins (not shown) extend through apertures (not shown) in board  812  and force pair of electrical contacts  864  and corresponding conductors (not shown) on key mat  832  into electrical contact. When the housing is opened, pins  864  no longer force conductors on key mat  832  and pair of electrical pads  864  into electrical contact and as a result electrical contact no longer exists between conductors on key mat  832  and pair of electrical contacts  864  and a suitable alarm or disablement occurs. 
     Reference is now made to  FIG. 10 , which is a simplified exploded view illustration of a secure keypad device constructed and operative in accordance with a yet further preferred embodiment of the present invention, and to  FIGS. 11A &amp; 11B , which are simplified sectional illustrations of part of the device of  FIG. 10 , taken along lines XI-XI in  FIG. 10 , in respective key non-depressed and key depressed operative orientations. 
     As seen in  FIGS. 10-11B , there is provided a secure keypad device  900  including a housing element  902  which, together with a back panel (not shown), defines a keypad device housing. Housing element  902  includes a display aperture  906 , through which a display (not shown) may be viewed, and an array  908  of key apertures  910 . 
     An anti-tamper board  912 , which includes an anti-tampering grid  914  formed of a multiplicity of interconnected anti-tampering electrical conductors, underlies top surface of housing element  902  and is provided with key apertures  920  in registration with key apertures  910 . Fixedly and electrically coupled to anti-tamper board  912  is a peripheral anti-tamper keypad enclosure  922 , which preferably includes an anti-tampering grid  923 , formed of a multiplicity of interconnected anti-tampering electrical conductors. 
     A key mat  932 , preferably formed of a resilient plastic or rubber, defines a plurality of depressible keys  934  which partially extend through key apertures  910  and  920 . Conductors  936  are formed on an underside surface  938  of key mat  932 , preferably on opposite sides of each of keys  934 . 
     An electrical circuit board  940 , which functions, inter alia, as a key contact board, is disposed in predetermined spaced relationship with key mat  932  and defines a plurality of pairs of adjacent electrical contact pads  942 , each pair underlying a corresponding conductor  936 . 
     When keys  934  are in a non-depressed operative orientation, such as that shown in  FIG. 11A , electrical contact does not exist between conductors  936  and pairs of adjacent electrical contact pads  942  lying thereunder and in registration therewith and between those pairs of adjacent electrical contact pads  942 . When keys  934  are in a depressed operative orientation, such as that shown in  FIG. 11B , electrical contact exists between conductors  936  and pairs of adjacent electrical contact pads  942  lying thereunder in registration therewith and between those pairs of adjacent electrical contact pads  942 . 
     Board  940  preferably includes an anti-tampering grid  944 , formed of a multiplicity of interconnected anti-tampering electrical conductors. Electrical connectors  946  are coupled to grid  944  and arranged for mating connection with an anti-tampering grid  954 , formed of a multiplicity of interconnected anti-tampering electrical conductors, which is formed on an additional electrical circuit board  956 . Fixedly and electrically coupled to boards  940  and  956  is a peripheral anti-tamper enclosure  958  which preferably includes an anti-tampering grid  957  formed of a multiplicity of interconnected anti-tampering electrical conductors. It is appreciated that the anti tampering grids  944 ,  954  and  957  on boards  940  and  956  and peripheral anti-tamper enclosure  958 , respectively, are interconnected so as to define an anti-tampering enclosure, which is coupled to and physically encloses anti-tampering detection circuitry  959 . Electrical connectors  980  and  982  preferably couple grids  914  and  923  on board  912  and enclosure  922 , respectively, to anti-tampering detection circuitry  959 . 
     In accordance with a preferred embodiment of the present invention, case-open switches, which sense physical tampering and opening of the housing are also located within the anti-tampering enclosure. In the illustrated embodiment the case-open switches are each embodied in conductors  962  mounted on key mat  932  and corresponding conductors (not shown) mounted on board  940 . Alternatively, the case-open switches may be constructed and operative as described hereinabove with reference to one of the embodiments shown  FIGS. 1A ,  1 B,  13 A- 14 B. 
     When the housing is closed, pins  966  extend through apertures  968  in board  912  and force conductors  962  into electrical contact with the corresponding conductors on board  940 . When the housing is opened, pins  966  no longer force conductors  962  into electrical contact with the corresponding conductors on board  940  and as a result electrical contact no longer exists between conductors  962  and the corresponding conductors on board  940  and a suitable alarm or disablement occurs. 
     Reference is now made to  FIGS. 12A and 12B , which are simplified exploded view illustrations, taken in respective opposite directions, of a secure keypad device constructed and operative in accordance with still another preferred embodiment of the present invention. 
     As seen in  FIGS. 12A and 12B , there is provided a secure keypad device  1100  including a housing element  1102  which, together with a back panel (not shown), defines a keypad device housing. Housing element  1102  includes, on a top surface  1104  thereof, a display aperture  1106 , through which a display (not shown) may be viewed, and an array  1108  of depressible keys  1110 , preferably integrally formed with housing element  1102 . 
     Keys  1110  are preferably formed of a resilient plastic or rubber and partially extend above top surface  1104  of housing element  1102 . As seen particularly in section A-A enlargement in  FIG. 12A , a contact surface  1112  of each of keys  1110  extends below top surface  1104  of housing element  1102 . Keys  1110  preferably include an attachment portion  1113  and a connection portion  1114 . 
     A flexible resilient protective partial enclosure  1116 , which includes an anti-tampering grid  1118 , formed of a multiplicity of interconnected anti-tampering electrical conductors, on a top surface  1120  thereof and on side surfaces  1122  thereof, is provided. A flexible cable  1124  is coupled to grid  1118 . 
     Disposed within protective partial enclosure  1116 , underlying top surface  1120 , is a key contact pad  1130 . Key contact pad  1130  is preferably a resilient, generally planar, pad formed of flexible and resilient plastic or rubber, having an array  1132  of raised resilient domes  1134  with conductors  1136  being formed on corresponding bottom facing surfaces  1138  thereof. 
     Disposed in predetermined spaced relationship with key contact pad  1130  is an electrical circuit board  1140 , which functions, inter alia, as a key contact board, defining a plurality of pairs of adjacent electrical contact pads  1142 , each pair underlying a corresponding conductor  1136 , preferably made of carbon, metal or combination of carbon/metal. The arrangement of key contact pad  1130  and of electrical circuit board  1140  is such that depression of a key  1110  by the finger of a user causes conductor  1136  to establish electrical contact with and between a corresponding pair of electrical contact pads  1142  lying thereunder and in registration therewith. When key  1110  is not depressed, no electrical contact exists between conductor  1136  and a pair of corresponding electrical contact pads  1142  or between the adjacent pads of the pair. 
     Electrical circuit board  1140  preferably includes an anti-tampering grid  1144  formed of a multiplicity of interconnected anti-tampering electrical conductors. An electrical connector  1146  is arranged for mating connection with flexible cable  1124 . The anti-tampering grids  1118  and  1144  are coupled to anti-tampering detection circuitry  1148 . 
     In accordance with a preferred embodiment of the present invention, case-open switches, which sense physical tampering and opening of the housing, are also located within partial enclosure  1116 . In the illustrated embodiment, the case-open switches are each embodied in a raised resilient dome  1150  formed on key contact pad  1130  and have conductors  1152  formed on an underside surface thereof. Domes  1150  preferably extend outwardly from the surface of key contact pad  1130  to a greater extent than do domes  1134 . Alternatively, the case-open switches may be constructed and operative as described hereinabove with reference to one of the embodiments shown  FIGS. 1A ,  1 B,  13 A- 14 B. 
     Disposed on electrical circuit board  1140  underlying each of domes  1150  are a corresponding number of pairs of adjacent electrical contact pads  1154 , each pair underlying a corresponding conductor  1152 . The arrangement of key contact pad  1130  and of electrical circuit board  1140  is such that as long as the housing is closed, conductors  1152  each are in electrical contact with and between a corresponding pair of electrical contact pads  1154  lying thereunder and in registration therewith. This electrical contact is ensured by the provision of pins  1156  integrally formed on housing element  1102 . When the housing is closed, pins  1156  urge element  1116  and thus corresponding domes  1150  on contact pad  1130 , and thus corresponding conductors  1152 , on the underside surfaces thereof, into electrical contact with corresponding electrical contact pads  1154 . 
     When the housing is opened, no electrical contact exists between conductor  1152  and corresponding pairs of electrical contact pads  1154  or between the adjacent pads of the pair of electrical contact pads  1154  and a suitable alarm or disablement occurs. 
     Disposed below electrical circuit board  1140 , there is provided a peripheral protective grid element  1160  which includes an anti-tampering grid  1162 , preferably coupled to a flexible cable  1164 , which is in turn connected to a connector  1166  on electrical circuit board  1140 . Peripheral protective grid element  1160  preferably is located interiorly of the side surfaces  1122  of enclosure  1116 . Fixedly attached to peripheral protective grid element  1160  and preferably disposed therebelow is a bottom protective grid element  1168  which includes an anti-tampering grid  1170 , which is coupled via contacts  1172  and via a connector  1174  which extends through an aperture  1176  formed in peripheral grid element  1160  into electrical contact with contacts  1178  on electrical circuit board  1140 . The anti-tampering grids  1162  and  1170  are coupled to anti-tampering detection circuitry  1148 . 
     It is appreciated by persons skilled in the art that the present invention is not limited by what has been particularly shown and described hereinabove. Rather the scope of the present invention includes both combinations and subcombinations of various features described hereinabove as well as variations and modifications thereto which would occur to a person of skill in the art upon reading the above description and which are not in the prior art.