JPH01143194A - Discharge lamp lighting device - Google Patents

Abstract

PURPOSE:To enable the easy start of a discharge lamp of high start voltage by applying the constitution wherein positive and negative output is taken out on the basis of one output end of a high-frequency inverter having a transformer, two switching elements connected in series between the positive and negative output ends are alternately turned ON and OFF repeatedly on a low frequency and the positive and negative rectangular waveform voltage of a low frequency is applied to the discharge lamp for the lighting thereof. CONSTITUTION:The series circuit of an inductor 7 having a high intensity discharge lamp 6 and an auxiliary winding 71 is connected between the inter-connection point of switching elements 51 and 52, and one end (b) of the secondary winding of an output transformer 23 for a high-frequency inverter 2. Also, a capacitor 4 is connected in parallel to the series circuit, thereby generating high-voltage pulses at both ends of the inverter 7 for application to an electric discharge lamp 6 and causing insulation destruction for a lighting start. The high-voltage pulses return through the capacitor 4 and, therefore, other elements are not influenced. According to the aforesaid circuit constitution, the discharge lamp 6 having high start voltage can be easily started.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Applications] 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, a steel glue cage transformer was used to light the lamp.However, this leakage transformer is large and heavy, so in recent years, high-frequency inverters with current limiting function have been used to reduce the size of the discharge lamp. Electric discharge lamps are increasingly being lit using lighter electronic ballasts.

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 to light the discharge lamp 105 with direct current to avoid the acoustic resonance phenomenon, or there is a method to select a frequency that does not cause the acoustic resonance phenomenon and light the discharge lamp 105. 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 the output of a high-frequency inverter is rectified and lit with direct current, a catahosis phenomenon occurs in which the light emitting part of the discharge lamp is biased toward one of the electrodes. The problem is 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 individual discharge characteristics. Ta.

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 using a high-frequency inverter for a discharge lamp that requires a high-voltage starting pulse.

[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, and a 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 output of the type and the negative output. a series circuit of an inductor and a discharge lamp, the inductor and the discharge lamp having two switching elements connected to each other, an auxiliary winding connected between a mutual connection point of the two switching elements and the output of the reference; A discharge lamp lighting device is constituted by a series circuit, a capacitor connected in parallel, and a drive circuit that drives the two switching elements so that they 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 configuration diagram of an embodiment of a discharge lamp lighting device according to the present invention. In FIG. As shown in FIG. 2, it is composed of switching elements 21 and 22, a leakage output transformer 23 having a current limiting function, a capacitor 24, and the like. 31.32 is the quadrature 2 of the high frequency inverter 2
30 A rectifying element having a cathode and an anode connected to one end a of the secondary winding, respectively, so that a positive output is generated at the anode of the rectifying element 31, and a negative output is generated at the cathode of the rectifying element 32. 51.52 is the rectifying element 3
This 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 and an auxiliary winding 71 are connected between the mutual connection point of the switching elements 51 and 52 and the other end of the secondary winding of the output transformer 23 of the high-frequency inverter 2. A series circuit of an inductor 7 is connected thereto, and a capacitor 4 is connected in parallel to the series circuit of the discharge lamp 6 and inductor 7. The switching elements 51 and 52 are configured to be alternately and repeatedly turned on and off at a low frequency, for example, about 50 Hz, by a drive circuit (not shown).

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 and supplied with DC power from the DC power supply 1 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
Rectifiers 31 and 32 connected to one end a of the secondary winding rectify the pulse. A negative half-wave rectified pulsating current is generated in the rectifying element 32.

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 winding of the output transformer 23 of the high-frequency inverter 2 through the rectifying element 31 is smoothed by the capacitor 4 and the inductor 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 inductor 7. flows through the switching element 52, and a direct current is supplied to the discharge lamp 6 in the opposite direction to the arrow.

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.

Furthermore, in order to start a discharge lamp with a high starting voltage such as a metal halide lamp, it is common to apply a high voltage pulse, but in the present invention, an auxiliary winding 71 is connected to an inductor 7 connected in series with the discharge lamp 6. By supplying a pulse current to this auxiliary winding 71 at the time of starting,
A high voltage pulse is generated at both ends of the inductor 7, and the discharge lamp 6
is applied to cause dielectric breakdown and start. Note that an inductor 7 for starting this discharge lamp 6
The high-voltage pulse generated by the capacitor 4 returns through the capacitor 4, so that it does not affect other elements.

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. Stable lighting can be obtained without causing any cataphoresis phenomenon. In addition, an inductor with an auxiliary winding generates a high voltage pulse to easily start a discharge lamp with a high starting voltage.
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 similarly 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 in this way, 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 the switching element 51, smoothed by the capacitor 4 and the inductor 7, and then the discharge lamp 6
Direct current is supplied in the direction of arrow A. Next, after a certain period of time, when the switching element 51 is turned off and the switching element 52 is turned on, a DC current is supplied to the discharge lamp 6 in the opposite direction to the direction of the arrow. 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.

This embodiment uses a full-wave rectification system, which 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, reducing the capacitance of the capacitor and the inductance of the inductor. This has the effect of being able to.

〔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 steady rest and the negative output. The two switching elements were alternately turned on and off at a low frequency, and a low-frequency positive and negative rectangular wave voltage was applied to the discharge lamp to light it.
It is possible to realize a discharge lamp lighting device using a high-frequency inverter that can achieve stable lighting without causing the acoustic resonance phenomenon caused by high-frequency lighting or the cataphosis phenomenon caused by DC lighting while reducing the size of the current-limiting element. In addition, since an inductor with an auxiliary winding is used, a discharge lamp with a high starting voltage can be easily started by applying a pulse to the auxiliary winding. Since the capacitor is used as a smoothing capacitor in a negative rectifier output circuit, 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 insulated, but the discharge lamp can be easily lit using a low-voltage power supply such as a buffer battery, and even when the discharge lamp is lit with a large voltage difference between the input and output. 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 is a switching element, 6 is a discharge lamp, and 7 is an inductor.

Claims (3)

[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 series circuit of an inductor and a discharge lamp having an auxiliary winding connected between the output of the inductor and the discharge lamp, a capacitor connected in parallel with the series circuit of the inductor and the discharge lamp, and the two switching elements are alternately turned on and off. A discharge lamp lighting device comprising a drive circuit that repeatedly turns off at a low frequency. (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. (3) The auxiliary winding of the inductor connected in series with the discharge lamp is configured to supply a pulse current that generates a high-voltage pulse at the time of starting. Discharge lamp lighting device.