Appeal No. 95-3876
Application 08/222,009
("[T]he actual words of the claim are the controlling
focus.").
Appellants implicitly invoke paragraph six in their
appeal brief where they rely on specific structures from the
specification in explaining the scope of their claim. (Paper
No. 18 (Sub. App. Br.) at 5.)
In contrast to the arrangement
disclosed in the Iwata et al patent,
in the circuit of the present
invention the voltage at the gate of
the IGBT is positively removed, so
that flash firing quickly stops and
the amount of emitted flash light is
more accurately controlled. Referring
to the circuit of Figure 1, for
example, when the firing of the flash
is to be terminated, a logic high
signal is generated at the STOP
terminal of the control circuit 4.
This signal renders the transistor Q6
conducting, which in turn bring the
transistors Q4 and Q5 into a non-
conducting state. As a result, the
supply of voltage from the
capacitor C2 to the gate of the IGBT
is interrupted. At the same time, the
transistor Q3 is brought into a
conducting state, to lower the voltage
at the gate of the IGBT, thereby
removing any capacitance component.
Consequently, the IGBT is immediately
turned off, and the flash is promptly
extinguished.
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