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 5588765
~ Apparatus for Analyzing Signatures
Inventor: Robert K. Campbell
SUMMARY OF THE INVENTION
In general terms, an apparatus and method are disclosed by which investigators
may make an accurate determination whether a plurality of signatures affixed
to different documents were made at the same or different times and/or with
the same or different pens. With regard to the apparatus, the forward end or
rim of a conventional ballpoint pen is modified to highlight the subtle
nuances which are characteristic of one's writing habits. More particularly, a
series of small indentations are formed around the periphery of the rim of the
pen. The indentations produce radially inward extending projections which are
positioned relative to the rolling ink ball to wipe off a small portion of the
ink that is applied to the paper from the ball. Therefore, the ink lines
deposited on the paper will contain small scratches or micro-striations. The
micro-striations will track the movement of the pen over the paper and not the
rotation of the ball. Thus, if the maker rotates the pen in his hand or
changes the angle of the pen relative to the paper, the location of the
micro-striations will undergo a corresponding change. By enlarging and
comparing the signatures side-by-side one another (e.g. with the aid of a
video camera), the respective scratch patterns of the signatures can be
analyzed for the purpose of determining whether the same pen was used to make
all of the signatures and whether the pen was rotated in the maker's hand.
With regard to the method, a fluorescent tracer compound that oxidizes in air
is added to the ink that is applied to the paper from a conventional ballpoint
pen, or the like. After the signature is made, the original tracer compound in
the ink will begin to oxidize into a new compound that fluoresces under
ultraviolet light at a different color compared with the color at which the
original tracer compound will fluoresce. By knowing the rate of oxidation of
the tracer compound and the respective magnitudes of the fluorescence emitted
by the original and new compounds, the elapsed time between the execution of
two signatures can be calculated by measuring the magnitude of certain colors
of fluorescent light emitted by the ink from the signatures for determining
and then comparing the amount of tracer compound that has been oxidized in
each signature.
5600443
~ Method of Determining the Age of Ink
Having Time Dependent Characteristics
Inventor: Thomas H. Frey; Isaiah Lieberman
SUMMARY OF THE INVENTION
A first embodiment of the present invention relates to the detection of pH
shifts of chemical compounds in the ink. pH shifts will change the composition
of the ink by promoting a chemical reaction. Such pH shifts are the result of
the evaporation of certain chemicals in the ink. Time dating is achieved by
depositing the ink on a writing surface and exposing the ink to the ambient
atmosphere so that a pH shift can be detected as the composition of the ink
changes with time.
If compound A in the ink is transformed to compound B at a known rate once the
ink has been deposited on a writing surface and exposed to the air, a simple
quantification of the ratio of A to B can be measured using standard
non-destructive analytical techniques, including spectrometry. The elapsed
time is then determined from predetermined calibrated time curves. The curves
generated are ratio curves which plot the amount of reactant divided by the
amount of product, versus time.
The use of a ratio solves the problems associated with measuring raw
characteristics. Given that the amount of ink applied to a document is small,
the quantity of the ink present is difficult to measure. Further complicating
this measurement is the fact that even if the quantity of ink present were
destructively measured, such quantity varies with different ink pens and
different signers. Some signers write lightly while others bear down. The
percentage of a scaler characteristic would therefore be most difficult to
ascertain.
However, by computing the ratio of the reactant to the product, the physical
amount of ink, or its concentration, is not important. Regardless of whether
there are large or small amounts of ink available for analysis, the ratio will
be the same for any particular stage of the reaction. Further, the use of a
ratio facilitates spectroscopy, a well known non-destructive method of
measuring the components present.
Performing a time dating analysis of an ink having time dependent
characteristics includes the steps of first measuring the spectral
characteristics of the ink in units of percent reflectance and then referring
to known reaction rates.
A second embodiment of the present invention relates to the oxidation of
compounds in the ink. Oxidation of specific compounds is a well understood
process which, under a given set of parameters, including time and reaction
rates, can be accurately predicted. Reaction rates can be buffered or modified
to give extended or shortened reaction times. Products of the oxidation
reactions as well as the amount of reactants remaining may be determined using
established spectroscopic or other applicable non-destructive analytical
techniques.
5759246
~ Ink with Time Dependent Characteristics
Inventor: Thomas H. Frey; Isaiah Lieberman
SUMMARY OF THE INVENTION
A first embodiment of the present invention relates to the detection of pH
shifts of chemical compounds in the ink. pH shifts will change the composition
of the ink by promoting a chemical reaction. Such pH shifts are the result of
the evaporation of certain chemicals in the ink. Time dating is achieved by
depositing the ink on a writing surface and exposing the ink to the ambient
atmosphere so that a pH shift can be detected as the composition of the ink
changes with time.
If compound A in the ink is transformed to compound B at a known rate once the
ink has been deposited on a writing surface and exposed to the air, a simple
quantification of the ratio of A to B can be measured using standard
non-destructive analytical techniques, including spectrometry. The elapsed
time is then determined from predetermined calibrated time curves. The curves
generated are ratio curves which plot the amount of reactant divided by the
amount of product, versus time.
The use of a ratio solves the problems associated with measuring raw
characteristics. Given that the amount of ink applied to a document is small,
the quantity of the ink present is difficult to measure. Further complicating
this measurement is the fact that even if the quantity of ink present were
destructively measured, such quantity varies with different ink pens and
different signers. Some signers write lightly while others bear down. The
percentage of a scaler characteristic would therefore be most difficult to
ascertain.
However, by computing the ratio of the reactant to the product, the physical
amount of ink, or its concentration, is not important. Regardless of whether
there are large or small amounts of ink available for analysis, the ratio will
be the same for any particular stage of the reaction. Further, the use of a
ratio facilitates spectroscopy, a well known non-destructive method of
measuring the components present.
Performing a time dating analysis of an ink having time dependent
characteristics includes the steps of first measuring the spectral
characteristics of the ink in units of percent reflectance and then referring
to known reaction rates.
A second embodiment of the present invention relates to the oxidation of
compounds in the ink. Oxidation of specific compounds is a well understood
process which, under a given set of parameters, including time and reaction
rates, can be accurately predicted. Reaction rates can be buffered or modified
to give extended or shortened reaction times. Products of the oxidation
reactions as well as the amount of reactants remaining may be determined using
established spectroscopic or other applicable non-destructive analytical
techniques.
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