JPH0574585A - Discharge lamp lighting device - Google Patents

Abstract

(57) [Summary] [Purpose] To increase the starting pulse voltage of a high-pressure discharge lamp. A pulse generating transformer is provided with a common primary winding and a pair of secondary windings having different numbers of turns, and the respective secondary windings are dispersedly provided at both ends of a high pressure discharge lamp. The number of turns of each secondary winding is different, so
Since the stray capacitances of the secondary windings are different, parasitic oscillation can be caused to increase the peak value, and a pulse voltage having a plurality of peaks in the basic period can be obtained.

Description

Detailed Description of the Invention

[Object of the Invention]

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge lamp lighting device for starting a high pressure discharge lamp by applying a high voltage pulse voltage.

[0003]

2. Description of the Related Art Conventionally, as this type of device, for example, one disclosed in Japanese Patent Laid-Open No. 1-279599 has been proposed. This shows that the pulse transformer is composed of a common primary winding and a pair of secondary windings, and the secondary windings are dispersedly provided at both ends of the high pressure discharge lamp. ing.

[0004]

High-pressure discharge lamps such as metal halide lamps and high-pressure sodium lamps require several KV to several tens of KVk starting pulses. Therefore, there is a demand for a discharge lamp lighting device that can generate a pulse voltage as high as possible using a small transformer.

The present invention meets such a demand, and an object thereof is to provide a discharge lamp lighting device capable of generating a higher pulse voltage in the case of transformers having the same size (capacity). To do.

[Constitution of Invention]

[0007]

According to a first aspect of the present invention, a pulse generating transformer is provided with a common primary winding and a pair of secondary windings having different numbers of turns. Are provided at both ends of the high pressure discharge lamp in a dispersed manner.

[0008]

[Action]

According to the first aspect of the invention, since the turns ratio of the secondary windings is different, the stray capacitances of these secondary windings are different. Therefore, when a pulse voltage is supplied to the common primary winding, parasitic vibration occurs due to the difference in the stray capacitance. Therefore, the combined pulse voltage applied to the discharge lamp includes the parasitic vibration. Then, due to the parasitic oscillation, the peak value of the combined pulse voltage is raised and the peak voltage has a plurality of peaks in the basic period. This facilitates starting the discharge lamp.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 is a high pressure discharge lamp. A pulse transformer 2 has a common primary winding 21, a pair of secondary windings 22 and 23.
have. The number of turns of the secondary windings 22 and 23 is different. For example, the winding ratio of the secondary windings 22 and 23 is 1: 1.5 or more. 3 is the primary winding 21
It is a pulse generation circuit for supplying a pulse voltage to. Reference numeral 4 denotes, for example, four FEs for alternating-currently lighting the discharge lamp 1.
A full bridge inverter having T41, 42, 43, 44. An oscillating circuit 5 gives ON / OFF signals to the FETs of the inverter 4.

Reference numeral 10 is a stabilized direct current power supply, which includes a switching device 11 for performing a chopper function, a diode 12 for a flywheel, an inductor 13, a smoothing capacitor 14,
The first voltage detection device 15, the second voltage detection device 16, and the current detection device 17 are included. The first voltage detection device 15 and the second voltage detection device 16 output a signal when the output voltage exceeds a predetermined upper limit value or falls below a predetermined lower limit value, and the switching device 11 Is stopped or controlled so as to be within the predetermined value of the upper limit and the predetermined value of the lower limit. Also,
The current detection device 17 controls the switching device 11 so that the load current becomes constant.
Further, although not shown, the switching device 11 may be controlled so that a load voltage is made constant by providing a third voltage detecting means. By doing so,
Impedance can be omitted as a current limiting device for the discharge lamp 1.

Next, the operation of this embodiment will be described. When the discharge lamp 1 is started, the pulse generation circuit 3 operates to supply a pulse voltage to the primary winding 21 of the pulse transformer 2. Therefore, a pulse voltage generated by boosting the secondary windings 22 and 23 is generated. Here, the number of turns of each of the secondary windings 22 and 23 is different, and the stray capacitance is different. Therefore, a pulse voltage with parasitic oscillation is generated with respect to the pulse voltage from the pulse generating circuit 3. For example, the secondary winding 22
The output waveform of is shown in Fig. 2 (a).
The output waveform of 23 is shown in FIG. 2 (b), and the combined output waveform is as shown in FIG. 2 (c). That is, the example of FIG. 2 is a case where the third harmonic is generated, and as is apparent from the figure, the peak value of the combined output is raised,
It is understood that there are three peaks in the basic period. The pulse voltage is usually designed around 100 KHz, and FIG. 2 shows an enlarged time axis.

In this embodiment, the full bridge inverter 4 is diagonally FE when the discharge lamp 1 is started, that is, while the pulse generating circuit 3 is outputting a pulse.
Turn on T41, 44 or 42, 43 continuously to discharge lamp 1
It may be configured to supply a direct current to the. In this case, it is possible to prevent the FET from being destroyed by the high-voltage pulse voltage, and to continuously flow a direct current to accelerate the rising of the discharge lamp 1.

Further, in this case, the relationship between the pulse generation period and the period in which the full bridge inverter 4 is operated in a direct current is as shown in FIG. 3, as shown in FIG. It is necessary to operate the inverter 4 in an alternating current. By doing so, it is possible to more reliably prevent the above-described FET from being broken and the early rising of the discharge lamp 1.

[0014]

As described above, according to the present invention, a pulse generating transformer is provided with a common primary winding and a pair of secondary windings having different numbers of turns, and each secondary winding is connected to a high pressure discharge lamp. Since the stray capacitances of the secondary windings are different from each other, the parasitic capacitance is caused by the different stray capacitances of the secondary windings, and the peak value is increased. It can be a pulsed voltage. Therefore, the certainty of starting the high pressure discharge lamp can be improved.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

FIG. 2 is a voltage waveform diagram showing the operation of FIG.

FIG. 3 is a diagram showing operation timings of a pulse generation circuit and a full-bridge inverter.

[Explanation of symbols]

 1 ... High-pressure discharge lamp, 2 ... Pulse generation transformer

Claims (1)

[Claims] 1. A high pressure discharge lamp; and a pulse generating transformer for applying a high voltage pulse voltage for starting to this discharge lamp,
The pulse generating transformer has a common primary winding and a pair of secondary windings having different numbers of turns, and the respective secondary windings are dispersedly provided at both ends of the discharge lamp. A discharge lamp lighting device characterized by the above.