JPS6021920Y2 - discharge lamp lighting device - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a discharge lamp lighting device that prevents leakage current from the discharge lamp.

Generally, the discharge current of a discharge lamp contains a high frequency component, and anode vibration is also a factor in generating the high frequency current.

The discharge lamp itself can be considered a large leakage current source, especially when an inverter is used for high-frequency lighting.

In addition, a discharge lamp is equipped with conductors such as a nearby conductor, the main body of the lighting equipment, and an outer box of the actuating device, but there is likely to be a relatively large stray capacitance between these conductors and the electrodes of the discharge lamp. Due to this stray capacitance, a large leakage current flows to the ground via the conductor.

Therefore, the earth leakage breaker may operate undesirably.

In addition, if the conductor is not grounded, if a human body touches the conductor, a high-frequency leakage current will flow between the discharge lamp, conductor, earth, and power supply line, which may pose a danger to the human body. For maintenance purposes, it is necessary to prevent leakage current from flowing as much as possible.

The object of this invention is to provide a discharge lamp lighting device that can prevent or reduce leakage current through the conductor.

This invention focuses on the first stray capacitance that exists concentratedly between one electrode of the discharge lamp and the conductor closest to this electrode, and the first stray capacitance that exists concentratedly between the other electrode of the discharge lamp and the conductor closest to this electrode. The second stray capacitance that is concentrated in the area and the attached voltage divider form a bridge that uses the discharge lamp as a leakage current source, and this bridge can be brought into equilibrium or close to equilibrium. This is a characteristic feature.

It is known that as a filter for high frequency noise, multiple capacitors are installed between the power lines and the connection point of these capacitors is grounded, but this filter shows an appropriate impedance value against the high frequency noise that becomes a problem. This is to prevent transmission to the power supply side, and does not constitute a bridge using the discharge lamp as a leakage current source, and is unrelated to the present invention.

An embodiment of this invention will be described below with reference to FIGS. 1 and 2.

Reference numeral 1 denotes a discharge lamp which has an ungrounded output terminal and includes a ballast, and is energized from an AC power source 3 via an actuating device 2 mainly composed of, for example, a high frequency inverter.

One pole of the AC power source 3 is generally grounded.

A conductor 4 consisting of a nearby conductor, a lighting fixture main body, an outer box of the actuating device 2, or the like is disposed adjacent to the discharge lamp 1.

Here, being close means that the stray capacitance existing between the discharge lamp 1 and the discharge lamp 1 causes leakage current to flow to an extent that is substantially problematic.

In addition, although the conductor 4 is directly grounded in FIG. 1, it does not necessarily have to be directly grounded, and if there is a large stray capacitance between the conductor 4 and the ground, it may be grounded via the stray capacitance. That will happen.

The discharge lamp 1 is provided with a voltage dividing circuit 6 in parallel, and its voltage dividing point a is connected to one pole side of the AC power source 3, which has the same potential as the ground in terms of high frequency.

In this embodiment, the voltage dividing circuit 6 is composed of two impedance elements, such as capacitors 5a and 5b, and the voltage dividing point a is directly connected to one grounded pole of the power source 3.

FIG. 2 shows a voltage dividing circuit 6 of these capacitors 5a and 5b,
FIG. 3 is a diagram showing the operating principle of leakage current reduction by representing the discharge lamp 1 and the stray capacitance formed between the discharge lamp 1 and the conductor 4 as an equivalent circuit.

In Fig. 2, 1a is the discharge lamp 1 regarded as a leakage current source, and ? a.

7b is the first and second stray capacitance existing between both electrodes of the lamp 1 and the conductor 4.

Although the stray capacitance is widely distributed between the electrode of the discharge lamp 1 and the conductor 4, the stray capacitance between the electrode of the discharge lamp 1 and the conductor closest to this electrode is the largest, and the stray capacitance is the largest. 2
As shown in the diagram, it can appear as something that exists in a concentrated manner.

Moreover, 5a and 5b are the above-mentioned capacitors.

Points a and b in this equivalent circuit are electrically connected to each other via the ground as described above, and have the same potential.

The operation of this invention will be explained below with reference to the equivalent circuit shown in FIG.

As is clear from the figure, this equivalent circuit constitutes a bridge.

Therefore, the values of capacitors 5a and 5b are selected,
By satisfying the above equilibrium condition of the bridge or approaching the equilibrium condition, there is no potential difference between points a and b, or the voltage difference is small, so no current, that is, leakage current, flows through points a and b. It is easy to see that the flow can be eliminated or substantially reduced significantly.

FIG. 3 shows another embodiment of this invention, in which an impedance element such as a capacitor 5c is further connected between the 0 point and the b point to obtain a balanced bridge. This is particularly suitable in cases where it is difficult to achieve bridge balance by using only one method.

Note that the same parts as in FIGS. 1 and 2 are designated by the same reference numerals, and explanations thereof will be omitted.

Additionally, the same applies to the case where an impedance element is connected between point d and point b.

Further, in this invention, the actuating device is not limited to an inverter, but may be a transformer or other device as long as it includes a ballast.

Furthermore, in this invention, the voltage dividing device may be a resistor or an inductor, or may consist of one element.

Furthermore, one pole side of the AC power supply to which the voltage dividing point of the voltage dividing circuit is connected may be grounded via an impedance, and in short, it is approximately the same as the ground for high frequency components such as those caused by vibration of the anode of a discharge lamp. It is sufficient that the voltage is at the potential.

Further, when the conductor is grounded, it may be grounded through an impedance of an appropriate value.

As mentioned above, this idea has a configuration in which a voltage dividing device is installed in parallel with the discharge lamp, and the voltage dividing point is connected to one pole side of the power source, which has the same potential as the ground in terms of high frequency. By configuring a bridge that serves as a current source, it is easy to balance this bridge, thereby reducing leakage current from the discharge lamp.
Further, it is possible to provide a discharge lamp lighting device that has a simple configuration and is inexpensive.

[Brief explanation of drawings]

Figures 1 and 2 are circuit diagrams and equivalent circuit diagrams showing one embodiment of this invention, and Figures 3 and 4 are circuit diagrams and equivalent circuit diagrams showing other embodiments of this invention. . 1... Discharge lamp, 2... Operating device, 3.
... AC power supply, 4 ... Conductor, 6 ...
...Partial pressure device.

Claims (1)

[Scope of utility model registration claim] AC power supply. An actuating device including a ballast, having an input terminal connected to the alternating current power source, and having an ungrounded output terminal. and a discharge lamp provided between the output terminals of this actuating device. and a conductor placed close to this discharge lamp. and a conductor disposed close to the discharge lamp. and a voltage dividing device connected to one pole side of the AC power source, the voltage dividing device being provided in parallel with the discharge lamp and having a voltage dividing point at the same potential as the ground in terms of high frequency. Device.