Indicia recognition apparatus
First Claim
1. Sensing and/or recognition apparatus for determining the genuineness and/or value of a security document having encoding indicia applied to the substrate surface thereof as a thin, transparent coating normally invisible and including particles driven into the surface of said substrate to a substantial depth wherein the particles of indicia material are possessed of an electrical conductivity different from the surrounding portions of the substrate surface, said apparatus comprising a housing, first and second electrode means arranged within said housing and spaced apart to define a gap therebetween, a source of high frequency alternating current coupled to said first and second electrode means for imparting a primary a.c. signal thereacross, means for positioning the document to be tested proximate with and spaced from at least said first electrode means, the encoding indicia being electrically exposed to said first and second electrode means whereby capacitively to induce instantaneously a secondary a.c. signal to said second electrode means providing said encoding indicia is present, said secondary signal being different from said primary signal and means for sensing instantaneously said secondary signal and generating an output signal responsive thereto.
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Abstract
Method and device for detecting the presence or the absence of conductive indicia carried by a supporting substrate which together comprise a security document, for the purpose of ascertaining the genuineness, value or other selected characteristic represented by said indicia. The indicia material is electrically conductive. The detecting device includes a housing and a sensing circuit including a source of high frequency a.c. alternating signals, first and second electrodes and the a.c. source coupled thereto.
A carrier for the document is arranged in proximity to said electrodes. The questioned document is placed in the vicinity of the electrodes whereby the presence of the conductive encoding indicia serves as a coupling mechanism between the electrodes for capacitively inducing a secondary a.c. signal from the first electrodes to the second which is different from the first mentioned a.c. signal, said secondary signal being of a selected measured magnitude representative of said presence and of encoding. The housing may be provided with a transparent cover so that the document remains visible during evaluation, and to assure good electrical contact over its area.
279 Citations
29 Claims
- 1. Sensing and/or recognition apparatus for determining the genuineness and/or value of a security document having encoding indicia applied to the substrate surface thereof as a thin, transparent coating normally invisible and including particles driven into the surface of said substrate to a substantial depth wherein the particles of indicia material are possessed of an electrical conductivity different from the surrounding portions of the substrate surface, said apparatus comprising a housing, first and second electrode means arranged within said housing and spaced apart to define a gap therebetween, a source of high frequency alternating current coupled to said first and second electrode means for imparting a primary a.c. signal thereacross, means for positioning the document to be tested proximate with and spaced from at least said first electrode means, the encoding indicia being electrically exposed to said first and second electrode means whereby capacitively to induce instantaneously a secondary a.c. signal to said second electrode means providing said encoding indicia is present, said secondary signal being different from said primary signal and means for sensing instantaneously said secondary signal and generating an output signal responsive thereto.
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23. Sensing and/or recognition apparatus for determining the genuineness and/or value of a security document having encoding indicia applied to the substrate surface thereof wherein the indicia material is possessed of an electrical conductivity different from the surrounding portions of the substrate surface, said apparatus comprising a housing, first and second electrode means arranged within said housing and spaced apart to define a gap therebetween, said first electrode means comprising a planar conductor arranged along a portion of said housing, a grounded guard electrode intermediate said first and second electrodes, a source of high frequency alternating current coupled to said first and second electrode means for imparting a primary a.c. signal thereacross, means for positioning the document to be tested proximate with and spaced from at least said first electrode means whereby capacitively to induce instantaneously a secondary a.c. signal to said second electrode means providing said encoding indicia is present, said secondary signal being different from said primary signal and means for sensing instantaneously said secondary signal and generating an output signal responsive thereto.
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24. Sensing and/or recognition apparatus for determining the genuineness and/or value of a security document having encoding indicia applied to the substrate surface thereof wherein the indicia material is possessed of an electrical conductivity different from the surrounding portions of the substrate surface, said apparatus comprising a housing, first and second electrode means arranged within said housing and spaced apart to define a gap therebetween, said first and second electrode means comprise respectively an excitor electrode arranged within the housing and plural receptor electrodes arranged in a row spaced one from the other and said row being spaced from said excitor electrode, said document to be tested adapted to be placed in bridging relation to said first and second electrodes whereby to bridge same and capacitively to induce said secondary signal to only those ones of said receptor electrodes in serial proximity to the indicia carried by said document, said excitor and receptor electrodes being disposed on opposite sides of said document but the excitor electrode being substantially offset from the receptor electrodes, a source of high frequency alternating current coupled to said first and second electrode means for imparting a primary a.c. signal thereacross, means for positioning the document to be tested proximate with and spaced from at least said first electrode means whereby capacitively to induce instantaneously a secondary a.c. signal to said second electrode means providing said encoding indicia is present, said secondary signal being different from said primary signal and means for sensing instantaneously said secondary signal and generating an output signal responsive thereto.
- 25. Sensing and/or recognition apparatus for determining the genuineness and/or value of a security document having encoding indicia applied to the substrate surface thereof wherein the indicia material is possessed of an electrical conductivity different from the surrounding portions of the substrate surface, said apparatus comprising a housing, first and second electrode means arranged within said housing and spaced apart to define a gap therebetween, said first and second electrode means comprising interleaved coplanar electrodes nested concentrically, a source of high frequency alternating current coupled to said first and second electrode means for imparting a primary a.c. signal thereacross, means for positioning the document to be tested proximate with and spaced from at least said first electrode means whereby capacitively to induce instantaneously a secondary a.c. signal to said second electrode means providing said encoding indicia is present, said secondary signal being different from said primary signal and means for sensing instantaneously said secondary signal and generating an output signal responsive thereto.
- 28. Sensing and or recognition apparatus for determining the genuineness and/or value of a security document having encoding indicia applied to the substrate surface thereof as a thin, transparent coating normally invisible and including particles driven into the surface of said substrate to a substantial depth wherein the particles of indicia material is possessed of an electrical conductivity different from the surrounding portions of the substrate surface, said apparatus comprising a housing, first and second electrode means arranged within said housing and spaced apart to define a gap therebetween, means for imparting a primary signal across said electrodes, said primary signal having a wave form exhibiting a rate of change with an equivalent frequency component which is at least 500 cycles, means for positioning the document to be tested proximate with and spaced from at least said first electrode means, the encoding indicia being electrically exposed to said first and second electrode means whereby capacitively to induce instantaneously a secondary signal by way of said indicia to said second electrode means providing said encoding indicia is present, said secondary signal being different from said primary signal and means for sensing instantaneously said secondary signal and generating an output signal responsive thereto.
Specification