JPH04264395A - Discharge lamp lighting device - Google Patents

Abstract

PURPOSE:To improve the starting characteristic of discharge lamp, and make a device compact by using a pair of charging circuits for generating pulse, and using divided cores for pulse transformer, and making the number of coil of secondary coils, which is wounded around of each core, different from each other. CONSTITUTION:A pulse transformer 17 consists of divided cores 22, 23 and a primary coil 24, which is wound around of the core 22, and a primary coil 25, which is connected to the coil 24 in series and wound around of the core 23, and secondary coils 18, 19, which are wound around of the cores 22, 23 and connected to a discharge lamp 13 in parallel with each other. When electric charge, which is charged in a capacitor 26, is discharged, pulse voltage is generated in both ends of the coils 24, 25, and is transmitted to the secondary coils 18, 19 in response to a ratio of the number of winding. The number of winding of the coil 18, which is wound around of the core 22, is larger than that of the coil 19, which is wound around of the core 23. Consequently, high pulse is generated from the coil 18, and low pulse is generated from the core 23, and they are applied to the discharge lamp 13 in parallel with each other to facilitate starting of the discharge lamp 13 and stabilize the lighting.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge lamp lighting device for starting and controlling the lighting of a discharge lamp.

0002

2. Description of the Related Art In recent years, as discharge lamps have been used for various purposes, there has been a demand for lighting devices that can be lit using various power supplies, are small in size, and can be lit stably. A circuit diagram of this conventional discharge lamp lighting device is shown in FIG. This discharge lamp lighting device connects the discharge lamp 33 to a lighting power supply 31 via a pulse transformer 36 which is a part of a starting device 32 as a means for starting and lighting the discharge lamp 33.
This method starts the discharge lamp by applying a high voltage pulse to the starting device 32, and in order to improve the startability of the discharge lamp 33, the starting device 32 is equipped with two sets of pulse generation charging circuits 34 and 3.
5 are provided, each of which generates a high pulse that causes breakdown between the main electrodes of the discharge lamp and a low pulse that maintains the discharge, and enables stable starting of the discharge lamp by applying them to the discharge lamp. This conventional example is JP-A-62-88
It is disclosed in Publication No. 295.

0003

However, in this conventional discharge lamp lighting device, the starting device is complicated because it has two sets of charging circuits. In particular, when lighting a discharge lamp that has a high breakdown voltage and large discharge sustaining energy, such as a metal halide lamp, it is necessary to stabilize the discharge using two types of discharge pulses in order to ensure sufficient insulation distance. Due to its nature, it was difficult to downsize the starter device.

0004

[Means for Solving the Problems] In order to solve the above problems, the discharge lamp lighting device of the present invention includes a discharge lamp and a first method for starting the discharge lamp by applying a high voltage pulse to the discharge lamp. In a discharge lamp lighting device that includes a pulse application section, a second pulse application section that generates a low pulse that keeps the discharge lamp lit after starting, and a power supply device, the first and second application sections are connected to a charging circuit. , has a switch element and two sets of divided cores, a primary winding wound around each core is connected in series to the charging circuit via the switch element, and a primary winding wound around each core is connected in series to the charging circuit. Two secondary windings are each connected to the discharge lamp via a power supply to apply high voltage pulses to the discharge lamp in parallel. Further, the two secondary windings are configured to have different numbers of turns.

[0005]

[Operation] In the above configuration, by using a pulse transformer with a divided core, height and By generating two sets of high voltage pulses with different widths and applying them to the discharge lamp in a superimposed manner, it is possible to ensure a breakdown between the main electrodes of the discharge lamp and to transfer the energy necessary to maintain the discharge to the discharge lamp. supplying.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a circuit diagram showing an embodiment of the discharge lamp lighting device of the present invention. As shown in FIG. 1, its components include a power supply device 11, a starter device 12, and a discharge lamp 13. The power supply device 11 is composed of a high frequency inverter 14, a choke coil 15, and a capacitor 16.
The discharge lamp 13 is connected via secondary windings 18 and 19 of a pulse transformer 17 constituting the starting device 12 so as to start and light the discharge lamp 13 . The starting device 12 includes a charging circuit 20, a discharge gap 21 which is a switch element, and a pulse transformer 17.

In this embodiment, the pulse transformer 17 includes divided cores 22 and 23, a primary winding 24 wound around the core 22, and a primary winding 24 connected in series with the primary winding 24 and wound around the core 23. It consists of a primary winding 25 and secondary windings 18 and 19 wound around cores 22 and 23, respectively, and connected in parallel to discharge lamp 13. Here, the primary windings 24 and 25 are connected to the discharge gap 21,
A series circuit is formed via a capacitor 26 that constitutes the charging circuit 20.

The charging circuit 20 uses an LC series resonant circuit composed of a choke coil 15 and a capacitor 16, which are components of the power supply device 11, to generate a resonant voltage across the capacitor 16, which is composed of a resistor 27 and a diode 28. It is rectified by a rectifier circuit, and the capacitor 26 is charged. The voltage charged in the capacitor 26 is applied to the discharge gap 2
When the breakdown voltage of 1 is reached, the discharge gap 21
breaks down, and the primary winding 2 of the pulse transformer 17
The electric charge stored in the capacitor 26 is discharged through the capacitors 4 and 25. This causes the primary windings 24 and 2
A pulse voltage is generated across the windings 5 and transmitted to the secondary windings 18 and 19 via the cores 22 and 23, respectively, depending on the turns ratio. At this time, in this embodiment, the number of turns of the primary windings 24 and 25 is different, for example, the primary winding 2
The number of turns of 4 is smaller than the number of turns of 25. This is determined to be the most appropriate value in order to generate appropriate stray capacitance and leakage inductance in the secondary winding.

On the other hand, in the secondary winding of this embodiment, the number of turns of the secondary winding 18 wound around the core 22 is greater than the number of turns of the secondary winding 19 wound around the core 23. Here, pulse transformer 1
Since the cores 22 and 23 of No. 7 are divided, the two generated pulses are transmitted independently. Therefore, a high pulse is independently generated from the secondary winding 18 wound around the core 22 and a low pulse is generated from the secondary winding 19 wound around the core 23.

The secondary winding 18 wound around the core 22 has a larger number of turns than the secondary winding 19 wound around the core 23, so the leakage inductance is large and the stray capacitance between the windings is large. Conversely, the secondary winding 19 wound around the core 23 has a smaller leakage inductance and a smaller stray capacitance between the windings than the secondary winding 18. Therefore, the high voltage pulse (a) generated across the secondary winding 19 is
As shown in FIG. 2, although the height is lower than the high voltage pulse (b) generated at both ends of the secondary winding 18, the ringing of the waveform during attenuation is small and it is difficult to cross zero, that is, the pulse width is Can generate wide high voltage pulses,
This supplies the energy necessary to maintain the discharge.

On the other hand, since the secondary winding 18 wound around the core 22 has a large leakage inductance and a large stray capacitance, the ringing of the waveform when the generated pulse is attenuated is large. Therefore, zero-crossing is likely to occur, and the pulse width is narrow. However, since the high voltage pulse generated by the secondary winding 18 is a pulse for causing breakdown between the main electrodes of the discharge lamp 13, it has a large Doesn't require energy. Therefore, the ringing of the waveform during attenuation is large, and there is no problem even if the waveform crosses zero during attenuation.

In this embodiment, two sets of pulses are generated independently in this way, namely, a high voltage pulse (b) which is high and narrow, and a high voltage pulse (a) which is low in height but wide.
are generated independently and applied to the discharge lamp 13 in parallel. Therefore, two sets of high voltage pulses as shown in FIG. 3 are applied to the discharge lamp 13 in a superimposed manner. That is, a high voltage that causes breakdown between the main electrodes of the discharge lamp 13;
Since the pulse voltage having the energy necessary for maintaining the discharge is simultaneously supplied to the discharge lamp 13, the discharge lamp 13
It is easy to start and lights up stably.

As described above, in this embodiment, even if the configuration is simplified by using one set of charging circuits for pulse generation, the high voltage pulse that breaks down between the main electrodes of the discharge lamp and the energy required to maintain the discharge are It is possible to generate high voltage pulses with . In addition, in this embodiment, the configuration of the charging circuit for pulse generation is simplified and the number of components can be reduced, making it easier to secure insulation distance and making the starter device smaller than the configuration of the conventional example. .

In this embodiment, a high frequency inverter is used as the power supply, but a commercial frequency AC power supply, a low frequency rectangular wave power supply, or a DC power supply may also be used. Further, although a discharge gap is used as the switch element, a semiconductor element may also be used, and the same effect can be obtained even if the switching element is made conductive or selectively conductive under external control. In addition, as a means for charging the pulse generation charging circuit, in this embodiment, the resonant voltage generated across the capacitor of the LC series resonant circuit is used, but it is also possible to charge the voltage necessary to break down the switching element. If so, other means may be used. Further, the present invention provides a pulse transformer 17.
A capacitor is connected to both ends of the primary winding 24 or 25 in order to increase the effect of changing the pulse width by manipulating the stray capacitance of the windings wound around the two divided cores 22 and 23. Also included.

[0015]

Effects of the Invention As is clear from the above description, according to the discharge lamp lighting device of the present invention, the charging circuit for pulse generation is assembled into a set, and a core divided into pulse transformers is used. By changing the number of turns of the two secondary windings wound on the starting device, a high-voltage pulse is generated from the starter device that ensures breakdown between the main electrodes of the discharge lamp and has the energy necessary to maintain the discharge. Thus, it is possible to provide a discharge lamp lighting device that improves the starting performance of the discharge lamp and realizes miniaturization of the starting device.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a discharge lamp lighting device according to an embodiment of the present invention.

[Figure 2] Waveform diagram of high voltage pulses generated by the discharge lamp lighting device of the same example

[Figure 3] Circuit diagram of a conventional discharge lamp lighting device

[Explanation of symbols]

11 Power supply device 12 Starting device 13 Discharge lamp 17 Pulse transformer 18 Secondary winding (first secondary winding) 19 Secondary winding (second secondary winding) 20 Charging circuit 21 Discharge gap 22 Core (first core) 23 Core (second core) 24 Primary winding (first primary winding) 25 Primary winding (second primary winding)

Claims (2)

[Claims] 1. A power supply device, a rectifier circuit that rectifies the output of the power supply device, a capacitor that charges the output of the power supply device via the rectification circuit, and a first and a second capacitor connected to both ends of the capacitor. a series circuit of primary windings; a switch element inserted into one of two connection points between the series circuit and the capacitor; a first core around which the first primary winding is wound; a second core around which a second primary winding is wound; a first secondary winding around the first core; and a first secondary winding around the second core; A second secondary winding having a different number of turns than a secondary winding, and a discharge lamp to which the outputs of the first secondary winding, the second secondary winding, and the output of the power supply device are applied. and a discharge lamp lighting device in which the first and second secondary windings are connected in parallel, and the first and second secondary windings are connected to both ends of the discharge lamp via the power supply device. . 2. The discharge lamp lighting device according to claim 1, wherein the switch element has a breakdown voltage at which it becomes conductive when the applied voltage is equal to or higher than a predetermined voltage.