Low-pressure discharge lamp, particularly fluorescent lamp high-frequency operating circuit with low-power network interference

US4782268A · kind A · utility

Assignee

• Patent-Treuhand-Gesellschaft fur elektrische Gluhlampen mbH · DE

Inventors

• Hans-Jurgen Fahnrich · Munich, DE
• Walter Hirschmann · Munich, DE

Key dates

• Filing date: Mar 9, 1987
• Grant date: Nov 1, 1988
• Expiry date: Mar 9, 2007

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S315/02
• WIPO field: Electrical machinery, apparatus, energy
• WIPO sector: Electrical engineering

Abstract

To suppress introduction of harmonics into the power supply network of a high-frequency operated fluorescent lamp, an input capacitor (C2) connected across a direct current supply (P1, P2) for a transistor push-pull high-frequency circuit--operating at between 25-50 kHz--has a pair of serially connected diodes (D4, D5) connected thereto. The junction point (M2) of the diodes is connected via a coupling capacity (C7) to a common junction (M1) of the push-pull connected transistors (T1, T2). The power line circuit has a line choke (L2, L2') connected, either in advance or behind a rectifier (G1) supplying direct current to the transistor push-pull circuit. The circuit effectively suppresses harmonics, particularly the third harmonic, without introducing additional losses in the circuit, especially if a further capacitor (C8) is connected in the resonance circuit of the fluorescent lamp and to the diode junction (M2) between the two diodes (D4, D5).