JPH01143193A - Discharge lamp lighting device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a lighting device for a high-intensity discharge lamp using a high-frequency inverter.

[Conventional technology]

Traditionally, when lighting a discharge lamp using commercial power, an iron-copper glued single-cage transformer was used, but since this leakage transformer is large and heavy, in recent years it has been replaced by a high-frequency inverter with a current limiting function. Discharge lamps are increasingly being lit using electronic ballasts that are smaller and lighter.

However, when a high-intensity discharge lamp such as a metal halide lamp or high-pressure sodium lamp is lit using an electronic ballast such as the one described above and a high-frequency voltage is applied, acoustic resonance may occur depending on the shape of the arc tube of the discharge lamp. There is sex. Therefore, conventionally, as shown in Fig. 4, a high frequency inverter 1
02, the output of the high-frequency inverter 102 is rectified by the rectifier 103, and the discharge lamp 105 is lit with direct current to avoid the acoustic resonance phenomenon, or the discharge lamp 105 is lit by selecting a frequency that does not cause the acoustic resonance phenomenon. Proposed. In addition, in FIG. 4, 101 is a DC power supply, 104
is a smoothing capacitor.

[Problem that the invention seeks to solve]

However, when rectifying the output of a high-frequency inverter and lighting it with direct current, a catahosis phenomenon occurs in which the light emitting part of the discharge lamp is biased towards one of the electrodes. For example, there is a problem in that it can only be applied to discharge lamps with short arc lengths. In addition, the method of lighting by selecting a frequency has the problem that it is difficult to put it into practical use because the frequency range in which discharge lamps can be stably lit is very narrow, or the stable frequency varies depending on the variation in the discharge lamp value. there were.

The present invention was made in order to solve the above-mentioned problems in the conventional discharge lamp lighting device using a high frequency inverter, and it is possible to stably light the discharge lamp without causing acoustic resonance phenomenon or catahosis phenomenon. An object of the present invention is to provide a lighting device for a discharge lamp using a high-frequency inverter.

[Means and effects for solving the problems] In order to solve the above problems, the present invention provides a high-frequency inverter using a DC power source, a transformer for converting the DC power into high-frequency power, and a high-frequency inverter using the high-frequency inverter. A rectifier circuit that converts the output into three outputs, a positive output, a negative output, and the reference output with one end of the output of the inverter as a reference, and connected in series between the pressure output and the negative output. a discharge lamp connected between a mutual connection point of the two switching elements and the output of the reference, a capacitor connected in parallel with the discharge lamp, and the two switching elements A discharge lamp lighting device is constituted by a drive circuit that drives the elements so that the elements alternately repeat on-off operations at a low frequency.

With this configuration, the positive and negative outputs are taken out with one end of the output of the high frequency inverter as a reference, and the positive and
Two switching elements connected in series between the negative output are turned on alternately at a low frequency.

By repeatedly turning off the discharge lamp, a low-frequency rectangular wave voltage is applied to the discharge lamp, and current in the opposite direction is alternately supplied to perform lighting. This makes it possible to prevent the occurrence of the acoustic resonance phenomenon caused by high-frequency lighting of the discharge lamp and the cathosis phenomenon caused by direct current lighting, thereby achieving stable lighting.

〔Example〕

Examples will be described below. FIG. 1 is a circuit diagram of an embodiment of a discharge lamp lighting device according to the present invention. In the figure, l is a DC power supply, and 2 is a high-frequency inverter with an output frequency of about several tens of KHz. For example, as shown in FIG. has been done. 31.32 is the output transformer 23 of the high frequency inverter 2
A rectifying element having a cathode and an anode connected to one end a of the secondary winding of the rectifying element 31, respectively, produces a positive output at the anode of the rectifying element 31, and a negative output at the cathode of the rectifying element 32. . 51.52 is the rectifying element 3
The rectifying element 32 is a switching element connected in series between the anode of the rectifying element 32 and the cathode of the rectifying element 32.

A high-intensity discharge lamp 6 such as a metal halide lamp is connected between the mutual connection point of the switching elements 51 and 52 and the secondary winding of the output transformer 23 of the high-frequency inverter 2. Further, a capacitor 4 is connected in parallel to the discharge lamp 6. The switching elements 51 and 52 are alternately and repeatedly turned on at a low frequency, for example, about 5011z, by a drive circuit (not shown).
Configured to be controlled off.

Next, the operation of the discharge lamp lighting device configured as described above will be explained. The high frequency inverter 2 having a current limiting function, which is supplied with DC power from the DC type a911, generates a high frequency voltage in the secondary winding of its output transformer 23. The high frequency output of this high frequency inverter 2 is
is rectified by the rectifying elements 31 and 32 connected to one end a of the secondary winding of the The rectifying element 32 generates a negative half-wave rectified pulsating current.

In such a state, the switching element 51 is activated by a control signal from a switching element drive circuit (not shown).
When the switching element 52 is turned on and the switching element 52 is turned off, a positive pulsating current that is half-wave rectified from the secondary S line of the output transformer 23 of the high frequency inverter 2 through the rectifying element 31 is smoothed by the capacitor 4 through the switching element 51. At the same time, the smoothed DC current is supplied to the discharge lamp 6 in the direction of arrow A toward the other end of the secondary winding of the output transformer 23.

Then, after a certain period of time has elapsed, for example 10 m5ec, the switching element 51 is switched on by the control signal of the drive circuit.
When the switching element 52 is turned off and the switching element 52 is turned on, the output of the high frequency inverter 2 is half-wave rectified by the rectifying element 32 to become a pulsating DC current, and the reference end of the secondary winding 23 is connected to the discharge lamp 6 and the switching element. 52, and a direct current is supplied to the discharge lamp 6 in the direction opposite to arrow A.

Thereafter, in the same manner, the switching elements 51 and 52 are alternately turned on and off at a low frequency, so that a low frequency rectangular wave voltage is applied to the discharge lamp 6, and a current in the opposite direction is alternately supplied. and lighting is performed.

As described above, in this embodiment, a leakage transformer is used in the transformer constituting the high-frequency inverter to provide a current-limiting function, thereby reducing the size of the current-limiting element. Katahoμ by
Stable lighting without cis phenomenon can be obtained. Further, a capacitor connected in parallel with the discharge lamp functions as a smoothing capacitor for the positive and negative rectified output circuits, and a single capacitor can supply a rectangular wave current with few high frequency components to the discharge lamp.

Note that it is also possible to use a chopper circuit that does not use a transformer instead of the high-frequency inverter and apply a low-frequency rectangular wave voltage to the discharge lamp to light it. However, when a chopper circuit is used, not only is it difficult to insulate the input and output, but also it is difficult to light the discharge lamp when the power source is a low voltage power source such as a battery. Furthermore, when there is a large voltage difference between the input and output, such as when lighting a discharge lamp with a low lamp voltage, a large power capacity is required for the load power, which has the disadvantage of significantly reducing power usage efficiency. be. On the other hand, when a transformer-type high-frequency inverter is used as in the present invention, all of the problems with the above-mentioned lighting system using a chopper circuit can be solved.

FIG. 3 is a circuit configuration diagram showing a second embodiment of the present invention. In this embodiment, the output transformer 23 of the high frequency inverter 2
An intermediate tap C is provided in the secondary winding of the secondary winding, and the intermediate tap C serves as a reference output connected to one end of the discharge lamp 6, and the output of the high frequency inverter 2 is full-wave rectified at both ends a and b of the secondary winding. This is constructed by connecting rectifying elements 31, 32, and 33, 34, respectively, and the other configurations are the same as the embodiment shown in FIG.

In the embodiment configured as described above, when the switching element 51 is turned on and the switching element 52 is turned off, the output of the high frequency inverter 2 is the same as that of the rectifying elements 31 and 33.
It is full-wave rectified by , passes through the switching element 51 , is smoothed by the capacitor 4 , and is directed to the discharge lamp 6 by the arrow A.
When the switching element 51 is turned off and the switching element 52 is turned on after a certain period of time, the DC current is supplied to the discharge lamp 6 in the opposite direction to the direction of the arrow. Ru. Thereafter, the switching elements 51 and 52 are turned on and off alternately at a low frequency in the same manner, thereby operating the discharge lamp 6 in the same manner as in the first embodiment.

Since this embodiment uses a full-wave rectification method, it not only improves the utilization rate of the transformer, but also reduces the high-frequency ripple of the DC output current by about 1/2, making it possible to reduce the capacitance of the capacitor. is obtained.

〔Effect of the invention〕

As described above based on the embodiments, according to the present invention, the positive and negative outputs are taken out from one end of the output of a high frequency inverter using a transformer, and are connected in series between the positive and negative outputs. The two switching elements are alternately turned on and off at a low frequency, and a low-frequency rectangular wave voltage is applied to the discharge lamp for lighting.This allows for high-frequency lighting while reducing the size of the current-limiting element. Accordingly, it is possible to realize a discharge lamp lighting device that can provide stable lighting without causing the acoustic resonance phenomenon caused by the cataphoresis phenomenon caused by direct current lighting or the cataphoresis phenomenon caused by direct current lighting. Further, since a capacitor is connected in parallel with the discharge lamp and used as a smoothing capacitor for the positive and negative rectified output circuits, a rectangular wave current with few high frequency components can be supplied to the discharge lamp with a single capacitor.

Also, since it uses a transformer-type high-frequency inverter,
Not only can the input and output be isolated, but the discharge lamp can be easily lit using a low-voltage power source such as a battery, and even when a discharge lamp with a large voltage difference between the input and output is lit. Advantages such as no reduction in power usage efficiency can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a circuit configuration diagram of one embodiment of a discharge lamp lighting device according to the present invention, FIG. 2 is a circuit diagram showing an example of a high frequency inverter, and FIG. 3 is a circuit diagram of another embodiment of the present invention. FIG. 4 is a circuit diagram showing an example of a discharge lamp lighting device using a conventional high-frequency inverter for direct current lighting. In the figure, 1 is a DC power supply, 2 is a high frequency inverter, and 3
1.32.33.34 is a rectifier, 4 is a capacitor, 5
1+ 52 represents a switching element, and 6 represents a discharge lamp.

Claims (2)

[Claims] (1) A high-frequency inverter using a DC power source, a transformer for converting the DC power into high-frequency power, and a positive output and a negative output based on one end of the output of the inverter, and the output of the high-frequency inverter. a rectifier circuit that converts the output of a reference into three outputs; two switching elements connected in series between the positive output and the negative output; a mutual connection point of the two switching elements and the reference; a discharge lamp connected between the output of the discharge lamp, a capacitor connected in parallel with the discharge lamp, and a drive circuit that drives the two switching elements so that they alternately repeat on-off operations at a low frequency. Equipped with a discharge lamp lighting device. (2) The discharge lamp lighting device according to claim 1, wherein the high-frequency inverter is configured using a leakage transformer having a current-limiting function.