JPH09190886A - Preheated electric discharge lamp lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce higher harmonic components of an input current by interpos ing an auxiliary inductor and an auxiliary capacitor in series with a capacitor for resonance and by setting the resultant impedance of the auxiliary inductor and the auxiliary capacitor to zero under the basic frequency. SOLUTION: Less adverse effect is evolved on the basis frequency component by setting the resultant impedance Z0 of an auxiliary inductor L0 and an auxiliary capacitor C0 to zero under the basic frequency of an AC supply V1. For the harmonic component, resultant impedance Z0 becomes high to reduce the higher harmonic components on a current I20 in a sub-winding L2 . The higher harmonic components induced into a ballast winding L1 is consequently reduced. Thus, the higher harmonic components on an input current I10 are reduced to prevent other electrical equipment from malfunction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a preheating type discharge lamp connected to an AC power source through a ballast winding, and a sub-winding and a resonance capacitor which are transformer-coupled with the ballast winding in a depolarizing relation. A series circuit is connected between the remaining terminals of the preheat type discharge lamp, and the preheat type discharge lamp resonates so that the rated preheat current flows at the time of preheating and the rated starting voltage is applied, and the rated tube current flows at the time of lighting. The present invention relates to a preheat type discharge lamp lighting device in which the capacity of a condenser is set.

[0002]

2. Description of the Related Art A conventional device will be described with reference to FIG. In the apparatus shown in FIG. 4, a preheating type discharge lamp F is connected to an AC power source V1 through a ballast winding L1, and a sub winding L2 and a resonance capacitor C1 which are transformer-coupled with the ballast winding L1 in a depolarizing relationship are connected in series. The circuit is connected between the remaining terminals of the preheated discharge lamp F. The operation waveforms of the apparatus of FIG. 4 are as shown in FIG. The current 12 of the sub winding L2 is a charge / discharge current of the resonance capacitor C1 and includes a harmonic component. Due to the influence, the input current 11 on the side of the ballast winding L1 which is transformer-coupled also contains a harmonic component. FIG. 5 shows that V1 = 200V (50
Hz), L1 = 1.33H, L2 = 0.79H, L1.
Mutual inductance between L2 = 1.01H, C1 =
The operating waveform is 6.5.5 μF and the preheating type discharge lamp is an FLR40S type fluorescent lamp.

[0003]

The input current of the above-mentioned prior art has many harmonic components, which causes other electrical equipment to malfunction. An object of the present invention is to reduce the harmonic components of the input current.

[0004]

According to the present invention, an auxiliary inductor and an auxiliary capacitor are inserted in series with a resonance capacitor, and the inductance of the auxiliary inductor and the capacity of the auxiliary capacitor are set under the fundamental frequency of an AC power supply. The combined impedance of both is set to zero. According to a second aspect of the present invention, the resonance capacitor and the auxiliary capacitor are replaced with a single capacitor having the same combined capacitance.

The combined impedance of the auxiliary inductor and the auxiliary capacitor is zero under the fundamental frequency of the AC power source and has almost no influence on the fundamental frequency component. The composite impedance becomes large with respect to the harmonic component, and the harmonic component of the current 12 of the sub winding L2 decreases. Therefore, the harmonic component induced in the ballast winding L1 is reduced, and thus the harmonic component of the input current 11 is also reduced.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION One embodiment of the present invention is shown in FIGS.
This will be described below. The parts reference numerals of FIG. 4 are used here as they are, and duplicate explanations are omitted as appropriate. In the apparatus of FIG. 1, the auxiliary inductor L0 and the auxiliary capacitor C0 are inserted in series with the resonance capacitor C1. The synthetic impedance Z0 consisting of The value of both impedances Z0 at the fundamental frequency of the AC power supply V1 is zero. Further, the inductance of the auxiliary inductor L0 and the capacitance of the auxiliary capacitor C0 are determined so as to be zero. The combined impedance of the auxiliary inductor L0 and the auxiliary capacitor C0 under the harmonic component is moderately large. The operation waveform of the apparatus of FIG. 1 is as shown in FIG. A sudden change in the charging / discharging current of the resonance capacitor C1 is suppressed by the auxiliary inductor L0, and the harmonic component of the current 120 in the auxiliary winding L2 is suppressed. Ballast winding L1 transformer-coupled with sub winding L2
The harmonic component induced in the input current I10 also decreases, and the harmonic component of the input current I10 also decreases. FIG. 2 shows that in the circuit of FIG. 1, L0 =
1.08H, C0 = 9.4 μF, and others are as shown in FIG.
It is an operation waveform in the same case. An example of another embodiment of the present invention will be described with reference to FIG. The resonance capacitor C1 and the auxiliary capacitor C0 in FIG. 1 are replaced with a single capacitor C9 having the same capacity as that of the resonance capacitor C1 and the auxiliary capacitor C0. The other points are the same as in FIG. The operation waveforms of the apparatus shown in FIG. 3 are similar to those shown in FIG. In FIG. 3, the two capacitors C1 and C0 need only be C9, so that the assembly becomes easy.

[0007]

According to the present invention, an auxiliary inductor and an auxiliary capacitor are inserted in series with a resonance capacitor, and the inductance of the auxiliary inductor and the capacitance of the auxiliary capacitor are combined impedance under the fundamental frequency of the AC power supply. Is set to be zero. Even if it is zero at the fundamental frequency, it has a composite impedance under the harmonic component, so that the effect can be utilized to reduce the harmonic component of the input current.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a device of the present invention.

FIG. 2 is an operation waveform diagram of the apparatus shown in FIG.

FIG. 3 is another circuit diagram similar to FIG. 1 showing another embodiment.

FIG. 4 is a circuit diagram showing a conventional device.

5 is an operation waveform diagram of the apparatus shown in FIG.

[Explanation of Codes] L1: Ballast winding L2: Sub winding L0: Auxiliary inductor C0: Auxiliary capacitor C9: Single capacitor C1: Resonance capacitor I10: Input current I20: Sub winding L2 current

Claims (2)

[Claims] 1. A preheating type discharge lamp is connected to an AC power source through a ballast winding, and a series circuit of a sub winding and a resonance capacitor, which is transformer-coupled to the ballast winding in a depolarizing relationship, is connected to the preheating unit. Connected between the remaining terminals of the discharge lamp, the capacity of the resonant capacitor is set so that the rated preheat current and rated starting voltage are applied to the preheated discharge lamp during preheating and the rated tube current flows during lighting. In a predetermined preheating type discharge lamp lighting device, an auxiliary inductor and an auxiliary capacitor are inserted in series with the resonance capacitor, and the inductance of the auxiliary inductor and the capacity of the auxiliary capacitor are both under the fundamental frequency of the AC power supply. The preheating type discharge lamp lighting device is characterized in that the combined impedance of is determined to be zero. 2. The preheating type discharge lamp lighting device according to claim 1, wherein the resonance capacitor and the auxiliary capacitor according to claim 1 are replaced with a single capacitor having a capacity equal to the series combined capacity thereof.