Appeal No. 2000-0946 Page 8
Application No. 08/704,217
Appellant’s first argument is not persuasive of any error on the examiner’s part
because, as discussed supra, claim 1 does not positively recite structure for
determining or calculating supply voltage from the measured rate of temperature
change. As for appellant’s second argument, we perceive no requirement in claim 1
that the power source provide a variable voltage.
Appellant’s statement that Figure 4 shows that the rate of change of the heating
element temperature is not proportional to the supply voltage is not well founded. While
appellant appears to be correct that the voltage applied to the heating element is kept
essentially constant, the changing slope of the current vs. time curve merely
illustrates that the rate of temperature change is a function of other variables, such as
melting of frost on the heating element, for example, in addition to the source voltage.
This is not inconsistent with the examiner’s finding that the rate of temperature change
is proportional to the source voltage. The supply of a higher voltage, and consequently
a higher current, to the heating element would reasonably be expected to increase the
temperature of the heating element at a higher rate, thereby also increasing the
resistance of the heating element at a higher rate. While the curve in Figure 4 does
flatten out (i.e., zero slope), regardless of voltage, over certain portions thereof, such as
during the melting of the frost, for example, claim 1 does not require that the voltage be
proportional to the rate of temperature change at all times or for any particular length of
time.
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