Appeal No. 97-1320
Application 08/431,001
record, and (2) the examiner improperly relied on his own
wisdom (albeit in hindsight) in the art of electronics to
support the rejection." The Examiner argues that the
modifications are not based on hindsight, but would have been
obvious to the one of ordinary skill in the art of electrical
engineering based on known design goals (EA5-6). We agree
with Appellants that the rejection is improperly based on
hindsight.
As explained in the description of the admitted prior art
of figure 1, the ratio of the resistance of resistor 28 to the
resistance of resistor 42 must be large, say, 10:1, to assure
that the gate-to-source voltage V is sufficient at low
GS
battery voltage to turn on the driver (specification, page 2,
lines 26-36). The capacitor 30 and resistor 42 are selected
to yield a fast time constant or charge rate (specification,
page 3, lines 1-10). "When the transistor [34] turns off, the
capacitor 30 discharges through resistor 28. Since
resistor 28 is ten times larger than resistor 42 the time
constant will be ten times larger, causing the turn-off event
to proceed at a much slower rate." (Specification, page 3,
lines 10-14.)
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Last modified: November 3, 2007