Appeal No. 2006-2920 Page 13
Application No. 10/813,501
across resistor 801 (fig. 5) [or resistor 800, fig. 4] becomes less negative
than Vr.
We agree with appellants that the inverting (-) input to comparator
840 shown in fig. 5 (i.e., corresponding to node Vs, fig. 4) can never have a
positive voltage potential (and associated positive current flow) with respect
to ground potential. We note that transistor 10 is OFF (i.e., with NO current
flowing through it) when field coil 32 is energized by current flowing through
transistor 9 [col. 5, line 66 through col. 5, line 3]. Again, we note that when
transistor 9 turns OFF, a negative backflow current flows initially through the
parasitic diode to provide a negative voltage drop across resistor 801 to
trigger the comparator to change state to turn ON (i.e., enable) transistors
10 and 841 that function to shunt the field coil backflow current to ground.
Therefore, we agree with appellants that the negative discharge current will
progressively become less negative as the field coil discharges through
transistors 10 and 841 (fig. 5) until a point is reached when the voltage
potential at Vs approaches ground potential (i.e., at the point of full field coil
discharge). However, we note that just before this point of full discharge is
reached, the comparator is triggered to change state (i.e., when Vs > Vr,
but both Vs and Vr are negative with respect to ground potential), as
discussed supra.
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