Appeal No. 2001-1893
Application No. 09/195,297
BACKGROUND
The invention is directed to a method of operating a resonant converter (e.g., an
electronic ballast for fluorescent lamps). Claim 1 is reproduced below.
1. A method of operation of a resonant converter which is adapted for use as
a ballast circuit for controlling operation of a gas discharge lamp connected
thereto, the converter being in a form of a full or half-bridge circuit having at least
first and second power switches which are respectively actuated by first and
second cyclic gating signals of substantially the same frequency, the gating
signal frequency being above a resonant frequency of said converter, the first
and second gating signals being substantially square waves having
complementary duty ratios; said method comprising:
effecting a change in operating state of said converter by increasing the
duty ratio of the first gating signal by a selected proportion and decreasing the
duty ratio of the second gating signal by the same selected proportion; and
the change in the duty ratio of each of said gating signals being ramped
so as to occur incrementally over a plurality of cycles thereof, the incremental
change per cycle being the same for both gating signals;
the ramped change in duty ratios producing said change in operating state
of said converter with substantial suppression of transient high voltages and
currents which would occur with a step-wise change in said duty ratios.
The examiner relies on the following reference:
Moisin et al. (Moisin) 5,583,402 Dec. 10, 1996
Claims 1-4 stand rejected under 35 U.S.C. § 103 as being unpatentable over
Moisin. A rejection of the claims under 35 U.S.C. § 112, first paragraph has been
withdrawn.
We refer to the Final Rejection (Paper No. 7) and the Examiner's Answer (Paper
No. 10) for a statement of the examiner's position and to the Brief (Paper No. 9) and the
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