Koninklijke Philips Corporation N.V.

Ramakrishnan Venkatraman

Romel Panlilio

Sree Venkit

Michael Y Zhang

Amr Ghazala

An electronic ballast with higher startup voltage includes converter with a switching circuit () responsive to a switching control signal () and operably connected to a DC bus (); a DC controller () comparing a sensed DC bus voltage signal and a reference DC bus voltage signal to generate the switching control signal (); and a startup adjustor operably connected to the DC controller () to adjust at least one of the sensed DC bus voltage signal and the reference DC bus voltage signal for a predetermined time at startup so that startup DC bus voltage is greater than steady state DC bus voltage.

Electronic ballast with higher startup voltage

A striation correction circuitis arranged to apply a first striation correction current to the first fluorescent lamp Land a second striation correction current to the second fluorescent lamp L. A first voltage appearing across the first fluorescent tube Ldue to the first striation correction current is substantially similar in magnitude but has inverted polarity with respect to a second voltage across the second fluorescent tube Ldue to the second striation correction current. Detection of an end-of-life condition of a fluorescent lamp is facilitated.

Symmetric cancelling anti-striation circuit

A filament cut-back circuit comprises an impedance circuit coupled in series between either an AC voltage source and a primary filament winding, or a secondary filament winding and a filament. In response to an alternating voltage from the AC voltage source when coupled in series thereto or an alternating voltage from the secondary filament winding when coupled in series thereto, the impedance circuit operates as a short circuit when the alternating voltage is at a preheat frequency and operates as an open circuit when the alternating voltage is at an operating frequency.

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Aurora, IL, United States of America

Ramakrishnan Venkatraman