Appeal No. 2006-2920 Page 10
Application No. 10/813,501
further, that this condition turns ON transistor 10. Significantly, we note
that the question before us turns upon the recognition that Asada’s
comparator 840 changes state when both input voltages are negative with
respect to ground potential, AND one input voltage crosses the other input
voltage (i.e., Vs < Vr or Vs > Vr). In particular, we note that negative
voltages have associated negative currents with respect to ground potential.
With respect to the operation of Asada’s second driving circuit 7 (as
shown in detail in fig. 1 and in block form in figs 4 and 5), we note that
when generation control signal Vc goes HIGH (i.e., indicating a low battery
condition), transistor 10 (i.e., low-side switching element 10) turns OFF a
certain delay time after the HIGH level Vc signal turns on transistor 702 (fig.
1), as disclosed at col. 3, lines 57-65.
The high level generation control signal Vc also turns on the transistor 702 of the
second driving circuit. Thus, electric charge of the gate of the low-side switching
element 10 is discharged through the resistor 701 and the transistor 702 to the
ground, so that the low-side switching element 10 turns off a certain delay time after
the generator control signal turns on the transistor 702. The delay time is set
according to the resistances of the resistor 701 and a capacity of the gate of the low-
side switching element 10.
We note again that Asada discloses when transistor 9 turns OFF the
high-side terminal of alternator field coil 32 becomes lower than ground
potential and a backflow (i.e., negative) current flows from a grounded
portion through the channel and parasitic diode to the high-side terminal of
field coil 32 [col. 4, lines 4-10; col. 8, lines 4-15]. We find this backflow
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