Transformerless fluorescent lamp operating circuit, particularly for a compact fluorescent lamp, with phase-shifted inverter control

US5349270A · kind A · utility

Assignee

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

Inventors

• Ulrich Roll · Munich, DE
• Werner Bernhard · Heubach, DE
• Ludwig Reiser · Gersthofen, DE

Key dates

• Filing date: Aug 25, 1992
• Grant date: Sep 20, 1994
• Expiry date: Aug 25, 2012

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S315/07
• WIPO field: Electrical machinery, apparatus, energy
• WIPO sector: Electrical engineering

Abstract

To eliminate the necessity for a saturated or air gap inductance to provide feedback circuit for a self-exciting oscillator including two active electronic switches (T1, T2) , for example MOSFETs, an auxiliary winding (HW1, HW2, . . . HW11) is inductively coupled to the resonance inductance (L2) present in the circuit for the discharge lamp (LP) anyway; and a pulse shaping - phase shifting network (R3, C3; R4, C4 . . . ) , devoid of inherent resonance, coupling the auxiliary winding to the active switching elements. The pulse shaping - phase shifting network is formed of a one or multiple-stage RC low-pass circuit, connected serially between the auxiliary winding and the control input, for example the gate, of the active switching element. The RC network can be constructed with variable elements, for example including PTC resistors, a varistor or the like, and may include a current source, protective circuits to protect against voltage peaks including Zener diodes. The low-pass characteristics of the pulse shaping - phase shifting network permits switching of the active semiconductor switches after the maximum current flow.