Counterfeit document detection apparatus

An apparatus for examining documents having a magnetic property with respect to authenticity, comprising;

• a document guide path for guiding a document in the apparatus;
• a magnetic transducer mounted along the document guide path for detecting a magnetic property of the documents moving along said document guide path, said magnetic transducer producing a transducer signal indicative of the magnetic property of the document when the magnetic property of the document is detected by said magnetic transducer:
• digital conversion means responsive to the signal from the magnetic transducer for producing representative digital values indicative of the transducer signal:
• accumulating means for generating an accumulated value based on the digital values from the digital conversion means:
• and
• comparison means responsive to said accumulated value for comparing said accumulated value with a predetermined value indicative of the magnetic property of an authentic document, whereby the document having an acceptable magnetic property can be determined
• wherein said accumulating means comprises first counting means for providing a first accumulated value as a count of digital values exceeding a first predetermined reference value, and second counting means for providing a second accumulated value as a count of digital values exceeding a second predetermined reference value.

A method of examining documents having a magnetic property with respect to authenticity, comprising the steps of;

• transporting a document along a guide path:
• detecting a magnetic property of the document during said transporting step:
• producing a detection signal indicative of said magnetic property of the document detected in said detecting step:
• sampling said detection signal and producing sampled values;
• accumulating the sampled values to produce at least one cumulative value, and
• comparing said cumulative value with a predetermined value indicative of the magnetic property of an authentic document, whereby a document having an acceptable magnetic property can be determined:
• wherein said accumulating step comprises accumulating a first cumulative value as a count of consecutive sampled values exceeding said predetermined threshold value.

An apparatus for examining documents having a magnetic property with respect to authenticity, comprising:

• a document guide path for guiding a document in the apparatus;
• document transport means for moving documents along the guide path at a selectable rate of at least 600 documents per minute;
• a magnetic transducer mounted along the document guide path for detecting a magnetic Property of the documents moving along said document guide path, said magnetic transducer producing a transducer signal indicative of the magnetic property of the document when the magnetic Property of the document is detected by said magnetic transducer;
• digital conversion means responsive to the signal from the magnetic transducer for producing representative proportional digital values indicative of the transducer signal;
• a signal conditioning circuit responsive to said magnetic transducer signal for providing a conditioned signal to the digital conversion means, the signal conditioning circuit comprising an analog integrator having a time constant that is less than a period of time required for the document to move along the guide path past the magnetic transducer, and wherein said digital conversion means is connected to receive the integrated signal;
• accumulating means for generating an accumulated numerical value based on the digital values from the digital conversion means;
• a replaceable non-volatile digital memory for storing predetermined numerical values, each value pertaining to a cumulative magnetic property of an authentic document;
• and
• comparison means connected with the memory and responsive to said accumulated numerical value for comparing said accumulated numerical value with at least one of the predetermined numerical values indicative of the magnetic Property of an authentic document, whereby the document having an acceptable magnetic property is determined after the document has moved along the guide path past the magnetic transducer, wherein said comparison means is configured to select the predetermined numerical value from the memory according to the selected rate of operation.

An apparatus for examining documents having a magnetic Property with respect to authenticity, comprising:

• a document guide path for guiding a document in the apparatus;
• a magnetic transducer mounted along the document guide path for detecting a magnetic property of the documents moving alone said document guide path, said magnetic transducer producing a transducer signal indicative of the magnetic property of the document when the magnetic property of the document is detected by said magnetic transducer;
• digital conversion means responsive to the signal from the magnetic transducer for producing representative proportional digital values indicative of the transducer signal;
• accumulating means for generating an accumulated numerical value based on the digital values from the digital conversion means;
• a replaceable non-volatile digital memory for storing predetermined numerical values, each value pertaining to a cumulative magnetic Property of an authentic document;
• and
• comparison means connected with the memory and responsive to said accumulated numerical value for comparing said accumulated numerical value with at least one of the predetermined numerical values indicative of the magnetic property of an authentic document, whereby the document having an acceptable magnetic property is determined after the document has moved along the guide path past the magnetic transducer.