US 6,310,447 B1 · Method for operating at least one fluorescent lamp, and electronic ballast therefor

Abstract

An integrated control and regulating circuit (IC) controls, via a half-bridge circuit (V2, V3), a load circuit (4) having the at least one fluorescent lamp (FL) by means of a drive circuit (CCO, SEL, HSD, LSD) regulated in a high-frequency manner. In the control and regulating circuit, each time the lamp is started and/or when there is a disturbance, a timer (PST, IT, CT) is started, which thus defines a sequence predetermined periods of time (Δpt, Δit, Δst, Δot), inter alia preheating period (Δpt) and ignition period (Δit). In a monitoring circuit (MON), the pulsed load current of the load circuit is cyclically monitored in comparison with reference levels (Mp, Mi, Mdo and Mo) which are respectively predetermined for the periods of time, in order to detect a normal state or a disturbance in the load circuit, to control the current regulation of the drive circuit (CCO, ISC, SEL, HSD, LSD) in the normal state, or to trigger an automatic disconnection of the electronic ballast in the event of a disturbance. During the ignition period (Δit), a current signal which is derived from the load current and is fed to the monitoring circuit (MON) has superposed on it an internally generated DC signal (DC) having a defined level. The value thereof is dimensioned in accordance with the types and/or circuits of the fluorescent lamp(s) which are used in the load circuit, with the result that the signal that is superposed in this way is adapted to the predetermined, fixed reference levels (e.g. Mp, Mi) of the monitoring circuit (MON) independently of the lamp selection in the load circuit.

Claims8

Dependent claims

A method for operating at least one fluorescent lamp (FL) by means of an electronic ballast with an integrated control and regulating circuit (IC) for regulating the load current in a load circuit (4) connected via a half-bridge circuit (V2, V3) and having the at least one fluorescent lamp (FL) by means of a drive circuit (CCO, SEL, HSD, LSD) of the half-bridge circuit, said drive circuit being regulated in a high-frequency manner, in which case, in the control and regulating circuit, comprising the steps of:

starting a timer (PST, IT, CT) for generating selection signals (S1, S2, S3, S4) each time the lamp is started and/or when there is a disturbance, wherein the selection signals define predetermined periods of time (Δpt, Δit, Δst, Δot),
activating respectively different, predetermined reference levels (Mp, Mi, Mdo, and Mo) by means of the selection signals, in a monitoring circuit (MON) for the load current,
emitting control pulses (QM) in the monitoring circuit as soon as the instantaneous value of the pulsed load current reaches the activated reference level,
identifying by means of control pulses a normal state or a disturbance in the load circuit as a function of their occurrence or failure to occur during the present period of time (Δpt, Δit, Δst, or Δot) and, in the normal state, feeding as regulator actual values to the drive circuit (CCO, ISC, SEL, HSD, LSD) or, in the event of a disturbance, triggering an automatic disconnection of the electronic ballast,
wherein, during the ignition period (Δit), the current signal which is derived from the load current and is fed to the monitoring circuit (MON) has superposed on it a DC signal (DC) which is generated internally in the control and regulating circuit (IC) and has a defined level, whose value is dimensioned in accordance with the types and/or circuits of the at least one fluorescent lamp which are used in the load circuit, with the result that the signal that is superposed in this way is adapted to the predetermined, fixed reference level (Mi) independently of the lamp selection in the load circuit.

2 more elements

An electronic ballast for operating at least one fluorescent lamp (FL) with a control and regulating circuit (IC) designed as an integrated circuit, to which there is connected, via a half-bridge circuit (V2, V3), a load circuit having the at least one fluorescent lamp for the regulation of the load current, in which case, in the control and regulating circuit, comprising:

a drive circuit (CCO, SEL, HSD, LSD), regulated in a high-frequency manner, for the half-bridge circuit (V2, V3),
a timer (PST, IT, CT) which is to be started anew each time the lamp is started and/or when there is a disturbance, and serves for generating selection signals (S1, S2, S3), the sequence of which defines predetermined periods of time (Δpt, Δit, Δst, Δot) for example a preheating period (Δpt) or an ignition period (Δit),
a monitoring circuit (MON) for the load current, which monitoring circuit is coupled to the half-bridge circuit, is designed as a threshold value comparator with a plurality of reference levels (Mp, Mi, Mdo, Mo) which are activated individually in each case by one of the selection signals, and generates a respective control pulse (QM) as soon as the pulsed load current reaches the instantaneously activated reference level,
in which case these control pulses identify a normal state or a disturbance in the load circuit as a function of their occurrence or failure to occur during the present period of time (Δpt, Δit, Δst or Δto) and, in the normal state, are fed as regulator actual values to the drive circuit (CCO, ISC, SEL, HSD, LSD) or, in the event of a disturbance, trigger an automatic disconnection of the electronic ballast,
wherein the control and regulating circuit (IC) furthermore has a DC source (IM), which is activated during the ignition period (Δit) until the actual ignition of the at least one fluorescent lamp (FL) and whose output is connected to the input of the monitoring circuit (MON) for the current signal derived from the load current and thus superposes on this load current signal a DC signal (DC) having a defined level, whose value is dimensioned according to the lamp types and/or circuits used in the load circuit.

2 more elements

Dependencies are inferred from the claim text.

Method for operating at least one fluorescent lamp, and electronic ballast therefor

Life of this patent

Method for operating at least one fluorescent lamp, and electronic ballast therefor

Life of this patent

Abstract

Claims8