Appeal No. 1997-2340 Page 10
Application No. 08/329,687
detecting the value of the main current of the GTO 1. The
output of this current detector 13 is applied to a control
circuit 14. This control circuit 14 is a circuit which serves
to selectively activate the sub snubber circuits 2a and 2b in
accordance with the magnitude of the main current value of the
GTO 1." Col. 3, ll. 14-20. In summary, the reference detects
the magnitude of the main current of a thyristor rather than
its self-turning-on.
Because Takahashi detects partial turn-off of some
thyristors and Mitsuoka detects the magnitude of the main
current of a thyristor, we are not persuaded that teachings
from the prior art would have suggested the limitations of
"detect means for detecting the self-firing of any of the
switching elements in the switching circuit due to the over-
voltage;" "detecting the self-firing of at least one switching
element due to an over-voltage in a switching circuit having
multiple parallel circuits;" or "a detection circuit which
detects a self-firing of either the switching element of said
first current path or the switching element of said second
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