Appeal No. 95-1238
Application 08/009,406
The invention relates to an apparatus and process for
measuring the percentage of ash in paper. On page 4 of the
specification, Appellants disclose that Figure 2 shows a plot of
x-ray energy verses mass absorption coefficient for three
constituents of ash, clay indicated by line 70, titanium dioxide
indicated by line 72 and calcium carbonate indicated by line 74.
Appellants disclose the important feature of the graph is to
illustrate that the K edges for line 72 and line 74 are very
close to the same value, about 5 KeV and 4 KeV respectively.
Appellants disclose that their invention takes advantage of this
characteristic in which only two x-ray tubes are needed to
determine the percentage of ash in paper when the ash is
comprised of clay, titanium dioxide and calcium carbonate.
The independent claim 1 is reproduced as follows:
1. A process for determining the concentration of a first
component of a mixture wherein the first component includes at
least three materials, said process comprising:
a) directing two beams of x-rays into the mixture, at least
one beam having a spectrum of x-rays having a plurality of
different energies, the first beam including x-rays having an
energy above the K-edges of at least two of the materials and the
second beam including x-rays having an energy below the K-edges
of the same at least two materials, wherein the energy
distributions of the two beams are different and are such that,
for each beam, the mass absorption coefficient for the same two
material is substantially equal, but different from the mass
absorption coefficient for the third material;
2
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