JPS629999B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a discharge lamp lighting device using high frequency power that facilitates starting.

Conventionally, in devices that use high-frequency power to light a discharge lamp using an inverter, etc., in order to facilitate starting, other output windings are connected to the inverter transformer separately from the winding that outputs power for energizing the discharge lamp. established,
There is a discharge lamp in which the output of the output winding is applied between one electrode of the discharge lamp and a nearby conductor. When starting the discharge lamp, by applying the voltage of the output winding in addition to the energizing voltage, a slight discharge is generated in one electrode of the discharge lamp, making it easier to start the discharge lamp. It is something.

However, since this device applies a high-frequency voltage between one electrode of the discharge lamp and the conductor even after the discharge lamp has started, leakage current flows due to stray capacitance that has low impedance to high frequencies, resulting in safety concerns. It was something that lacked. Furthermore, providing another output winding in the inverter transformer is disadvantageous in terms of manufacturing and cost.

The present invention has been made to eliminate the drawbacks of the conventional devices, and relates to a discharge lamp lighting device that has low leakage current, has a simple structure, and facilitates starting of the discharge lamp.

The present invention applies a single-pole smoothed DC voltage or a DC voltage containing low-frequency ripples between one electrode of a discharge lamp and a conductor in a rectifier circuit provided for converting the output of an AC power source into high-frequency power. By doing so, leakage current due to the influence of stray capacitance can be reduced, and the discharge lamp can be started easily.

An embodiment of the present invention will be described below with reference to the drawings. Reference numeral 1 denotes an alternating current power source, one pole of which is grounded, and is, for example, a commercial frequency alternating current power source. 2
is a rectifier circuit whose input terminal is connected to the AC power supply 1 and whose output terminals are connected with a smoothing capacitor 3. Note that the smoothing capacitor 3 is not necessarily required. Reference numeral 4 denotes a conversion device, such as a transistor inverter, a thyristor inverter, etc., and known devices can be used as they are. 5 is a transformer, and when the converting device 4 is an inverter, for example, it is a primary winding and a secondary winding of the inverter transformer. Reference numeral 6 denotes a discharge lamp, such as a fluorescent lamp, which is energized by the output of the converter 4 via a choke coil 7 as a stabilizer. Electrode of discharge lamp 6
Preheating means for f ₁ and f ₂ is not shown, but they can be preheated by, for example, the output of the converter 4 or a separate power source. Reference numeral 8 denotes a conductor, such as a nearby conductor, or the main body of the lighting device, which is grounded. For example, a positive electrode voltage of the rectifier circuit 2 is applied between one electrode f ₂ of the discharge lamp 6 and the conductor 8. That is, in this embodiment, the discharge lamp 6
A series circuit of capacitors 9 and 10 is provided in parallel, and the middle point of this series circuit is connected to a rectifier circuit 2.
is connected to the positive terminal of the Further, the other electrode f ₁ of the discharge lamp 6 and the conductor 8 are connected via a capacitor 11 . However, the electrode of the discharge lamp 6 and the conductor 8
It does not necessarily have to be connected to. In this embodiment, the relationship between the capacitances of the capacitors 9, 10, and 11 is as follows: capacitor 9≫capacitors 10, 11
has been selected.

Next, the effect will be explained. The output of the AC power supply 1 is rectified and smoothed by a rectifier circuit 2 and a smoothing capacitor 3, and then supplied to a converter 4. Therefore, this converter 4 converts the rectified and smoothed DC voltage into, for example, several KHz.
It is converted into a high frequency alternating current voltage of up to several tens of KHz and applied to the discharge lamp 6 via the chiyoke coil 7. At the same time, the positive voltage of the rectifier circuit ₂ is applied between the electrode f 2 of the discharge lamp 6 and the conductor 8. Therefore, a voltage equal to the sum of the high-frequency AC voltage and the rectified voltage is applied between the electrode f ₂ and the conductor 8 of the discharge lamp 6, and the discharge lamp 6 immediately starts a slight discharge and is easily started. . That is, in this embodiment, the rectified voltage is applied to the connection point of capacitors 9 and 10, but as described above, capacitor 9 is applied to capacitor 11.
Since the capacitance is selected to be large compared to the capacitor 11, most of the rectified voltage appears across the capacitor 11. In addition, the high frequency AC voltage is supplied to capacitors 9 and 1.
Most of the 0 is applied to the capacitor 10. Therefore, a voltage equal to the sum of the positive electrode voltage of the rectifier circuit 2 and the high frequency voltage is applied between one electrode f ₂ of the discharge lamp 6 and the conductor 8, and a slight discharge is started.

After the discharge lamp 6 is started, the discharge lamp 6 continues to be lit by the output of the converter 4. Further, after the discharge lamp 6 is started, the voltage across the discharge lamp 6 decreases, so that leakage current due to high frequency power is small. Furthermore, since the rectified voltage of the rectifier circuit 2 is hardly affected by stray capacitance, there is almost no leakage current due to this voltage.

Note that in this embodiment, capacitors 9 and 1
0 and 11, it is easy to further reduce leakage current. That is, if the discharge lamp 6 is equivalently represented as a leakage current generation source, it can be shown as shown in FIG. In Figure 2, 1
2 and 13 equivalently represent the stray capacitance between the electrode of the discharge lamp 6 and the conductor 8. As shown in the second diagram, this embodiment constitutes a bridge, and the capacitors 9, 10, 1 that constitute this bridge
Since the value of 1 is selected as described above, leakage current can be reduced. That is, capacitor 9
The product of the impedance of the stray capacitance 13 and the product of the impedances of the capacitor 10 and the capacitor 11 can be made equal.

Note that the present invention is not limited to the above embodiments. As a means of applying the output voltage of the rectifier circuit between the discharge lamp and the conductor, one pole of the rectifier circuit may be connected directly to the electrode of the discharge lamp, or it may be connected through another impedance. good. In other words, it is not necessary to construct a bridge as in the above embodiment. Furthermore, the output voltage of the rectifier circuit may be applied between any electrode of the discharge lamp and the conductor.

As detailed above, the present invention applies a smooth DC voltage or an output voltage of a rectifier circuit containing low frequency ripples between one electrode of a discharge lamp and a conductor. In addition, since the output voltage of the rectifier circuit is hardly affected by stray capacitance, it is possible to provide a discharge lamp lighting device that can reduce leakage current.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram showing one embodiment of the present invention, Figure 2 is a circuit diagram showing an embodiment of the present invention.
The figure is an equivalent circuit diagram of a part of FIG. 1. 1... AC power supply, 2... Rectifier circuit, 4... Conversion device, 6... Discharge lamp, 8... Conductor, 9, 10, 1
1... Capacitor.

Claims (1)

[Scope of Claims] 1. An AC power source whose one pole is grounded, a rectifier circuit whose input end is connected to the power source, a converter that converts the output of the rectifier circuit into high-frequency power, and an output of the converter that converts the output of the rectifier into high-frequency power. A discharge lamp to be energized, a conductor disposed close to the discharge lamp and grounded, and means for applying an output voltage of the rectifier circuit between one electrode of the discharge lamp and the conductor. A discharge lamp lighting device characterized by: 2. The means includes a voltage dividing circuit provided in parallel with the discharge lamp and having a voltage dividing point connected to one pole of the rectifier circuit, and an impedance provided between one electrode of the discharge lamp and the conductor. The discharge lamp lighting device according to claim 1, characterized in that the discharge lamp lighting device comprises an element.