Magnetic document validator employing remanence and saturation measurements
AssigneeBrandt, Inc.
InventorDavid R. Bryce
Life of this patent
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Abstract
A method of and apparatus for determining the genuineness of a document such as a currency note printed at least in part with magnetizable ink in which there is produced a first signal as a measure of the saturation magnetization of a portion of the document printed with the ink and a second signal as a measure of the remanent magnetization of said portion and in which the ratio of the second signal to the first signal is determined as a measure of genuineness of the document.
Claims23
Apparatus for determining the genuineness of a document printed at least in part with magnetic ink including in combination
- means for applying to a portion of a document printed with magnetic ink a magnetizing force sufficient to saturate the magnetic ink in said portion,
- means for measuring the saturation magnetization of said portion while applying said saturating magnetic force to produce a first signal representing the saturation magnetization of said portion,
- means for measuring the magnetization of said portion after the removal of a magnetizing force from said portion to produce a second signal representing the remanent magnetization of said portion,
- and means for comparing said first and second signals with each other to provide an indication of the genuineness of said document.
Apparatus for determining the genuineness of a document printed at least in part with magnetic ink including in combination,
- means for applying to a portion of a document printed with magnetic ink a magnetizing force sufficient to saturate the magnetic ink in said portion,
- means for measuring the saturation magnetization of said portion while applying said saturating magnetic force to produce a first signal representing the saturation magnetization of said portion,
- means for measuring the magnetization of said portion after the removal of a magnetizing force from said portion to produce an initial signal representing the remanent magnetization of said portion,
- means for amplifying said initial remanence signal by a predetermined factor to produce a second signal at a level above that of the first signal for a counterfeit document while leaving said signal at a level below that of the first signal for a genuine document,
- means for comparing said first and second signals,
- and means responsive to said comparing means for producing a suspect signal whenever said second signal is greater than said first signal.
A method of determining the genuineness of a document printed at least in part with magnetizable ink including the steps of
- applying to a portion of a document printed with magnetic ink a magnetizing force sufficient to saturate the magnetic ink in said portion,
- measuring the saturation magnetization of said portion while applying said saturating magnetic force to obtain a saturization magnetization measurement,
- measuring the magnetization of said portion after the removal of a magnetizing force from said portion to obtain a remanence magnetization measurement
- and comparing said remanence magnetization measurement with said saturation magnetization measurement to provide an indication of the genuineness of said document.
Dependencies are inferred from the claim text.