Appeal No. 1997-2340 Page 9
Application No. 08/329,687
Although Takahashi teaches detecting, it does not detect
the self-turning-on of a switching element absent an ON
command. To the contrary, "a partial turn-off phenomenon
itself is detected ...." Col. 7, ll. 11-12. The reference
describes the phenomenon as follows.
In more detail, when many thyristors are turned off,
reverse voltages are required to be applied across
the corresponding thyristors during long enough
intervals that all of the thyristors can withstand
forward voltages subsequently applied thereto. In
case these reverse voltage intervals are
insufficient, when a forward voltage is applied
across the thyristors, some thyristors can withstand
the forward voltage, but the remaining thyristors
fail to perform forward recovery, i.e., recover
their features to withstand the forward voltage,
with the result that they maintain their conductive
states. This phenomenon is a so-called partial
turn-off phenomenon.
Col. 1, ll. 28-40. In summary, Takahashi detects partial
turn-off of some thyristors rather than their self-turning-on.
For its part, although Mitsuoka teaches detecting, it
does not detect the self-turning-on of a switching element
absent an ON command. To the contrary, "the main current path
of the GTO 1 is provided with a current detector 13 for
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