Appeal No. 1998-1915 Page 2
Application No. 08/670,123
discharge lamp is lit or started using an alternating current
(AC). In the case where the lamp is in a cold state, the
intensity of light generated by the lamp remains low until the
pressure of a metal vapor therein rises to a sufficient level.
Immediately after being started from the cold state, however,
the lamp goes out upon a change of the polarity or direction
of a lamp current between a positive side and a negative side.
The appellants' lighting device operates on a high-
voltage discharge lamp. The device includes a starting switch
and a bridge control circuit. The circuit supplies a low
frequency AC power to the lamp immediately after the lamp is
activated. After a time, the circuit supplies a higher
frequency AC power to the lamp.
Claim 9, which is representative for our purposes,
follows:
9. A lighting device for a discharge lamp,
comprising:
a starting switch movable into an on position;
first means connected to the starting switch for
feeding an alternating current of a variable
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