JPS6139489A - Device for firing discharge lamp - 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 the Invention) The present invention relates to a discharge lamp lighting device that generates a pulse every half cycle of an AC power source to start and maintain lighting of a discharge lamp. The present invention relates to a discharge lamp lighting device that aims to improve the luminous flux maintenance rate (luminous efficiency) by eliminating the

(Background of the Invention) As a conventional discharge lamp lighting device, one having the configuration shown in FIG. 1 is known. The device shown in the figure has one terminal a of an AC power supply 1.
One end of an inductor (choke) 2 is connected to , and a discharge lamp 3 is connected between the other end C of the inductor 2 and the other terminal of the AC power source 1 , and the middle tap d of the inductor 2 and the other terminal of the AC power source 1 are connected A switch device 4 is connected between the terminal b and the terminal b. As a result, a first closed circuit (main circuit) consisting of the AC power supply 1, the inductor 2, and the discharge lamp 3 is formed. Further, the switch device 4 includes a diode 9 bridge 4
1, a transistor 42, etc., and is turned on for a predetermined period according to a signal given from a control circuit (not shown) in the first half of each half cycle of the AC power supply 1. 2 closed circuits are constructed.

In this device, energy is stored in the inductor 2 by the second closed circuit, and the switch device 4
During the off period, the energy accumulated in the inductor 2 is superimposed on the AC power supply 1 and applied to the discharge lamp 3 through the first closed circuit. Thereby, the discharge lamp 3 can be started and kept lit.

Such a discharge lamp lighting device does not need to separately provide a starting pulse generating circuit and a step-up transformer type ballast, so the device can be configured to be small and lightweight.

By the way, in such a discharge lamp lighting device, the second
As shown in the figure, since the discharge lamp 3 has a lighting pause period Tyt, a high restriking voltage Vreig occurs, and the sputtering phenomenon shown in the shaded area in FIG. 2(b) occurs every half cycle of the AC power supply 1. The luminous flux maintenance rate is poor because it is repeated.

FIG. 2 (bl) is a partial enlarged view of the lamp voltage. In the figure, the shaded area is the glow-arc transition period, and the longer this period, the more intense the sputtering and the worse the luminous flux maintenance factor.

(Object of the invention) The object of the present invention is to solve the problems of the conventional type described above.
In the so-called every-cycle lighting type discharge lamp lighting device,
The purpose is to lower the restrike notice voltage due to the restrike pulse, thereby improving the luminous flux maintenance factor.

(Structure of the Invention) In order to achieve the above object, the present invention uses a 4t AC power source and 1.
an inductance device, a discharge lamp that forms a first closed circuit together with these alternating current/power sources and the inductance device; a switch device forming a closed circuit, the energy accumulated in the inductance device by the second closed circuit during the on period of the switch device is superimposed on the AC power source during the subsequent off period of the switch device. In the discharge lamp lighting device, a second switch device is connected in series between the inductance device and the discharge lamp, and a second switch device is connected in series between the inductance device and the discharge lamp.
0 characterized in that a series circuit of an impedance element and a third switch which is controlled to be turned on and off alternately is connected to the second switch in parallel to the series circuit with the switch device. Hereinafter, the present invention will be explained in detail using the drawings.

Note that parts common or corresponding to those of the conventional example are represented by the same reference numerals.

FIG. 3 shows a circuit configuration of a discharge lamp lighting device according to an embodiment of the present invention. The discharge lamp lighting device shown in the figure is different from the one shown in FIG. 1 in that a second switch device 5 is connected in series between the inductor 2 and the discharge lamp 3, and A series circuit of a resistor 6 and a third switch device 7 is connected in parallel to the series circuit of , the second switch device 5 is in opposite phase to the switch device 4, and the third switch device 7 is connected to the switch device 4. It is designed to turn on and off in the same phase as the

Therefore, when the switch device 4 is turned on (TM), the third
When the switch device 7 is turned on, lamp current is supplied from the AC power source 1 to the discharge lamp 3 via the resistor 6 and the switch device 7, thereby eliminating a pause period for the lamp current. As a result, in this lighting device, as shown in FIG. 4, there is no lighting pause period and there is no glow state due to re-ignition. That is, since only arc discharge continues and sputtering does not occur, the luminous flux maintenance rate is good.

In FIG. 3, the second switch device 5 is turned off while the switch device 4 is on (TM), thereby supplying power from the AC power source 1 to the lamp 3 via the resistor 6 and the third switch device 7. The current flowing through the inductor 2 and the switch device 4 is caused to flow out through the inductor 2 and the switch device 4, thereby preventing deterioration of efficiency or occurrence of a lighting stop period.

(Effects of the Invention) As described above, according to the present invention, since the lighting pause period is eliminated, the ions of the arc are not cooled, and only a small amount of energy is required for restriking. Therefore, high restriking voltage is not generated, and the luminous flux maintenance factor can be significantly improved. - To give an example, conventional re-ignition voltage Vreig is 5o
ov was reduced to 200v according to the present invention.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram of a conventional discharge lamp lighting device, and Figure 2 is a circuit diagram of a conventional discharge lamp lighting device.
FIG. 3 is a circuit diagram of a discharge lamp lighting device according to an embodiment of the present invention; FIG. 4 is a lamp voltage waveform and lamp current waveform of the device shown in FIG. 3. It is a diagram. 1... AC power supply, 2... Inductor,
3...Discharge lamp, 4...Switch device,
5... Second switch device, 6... Resistor, 7... Third switch device. Patent Applicant Toshiba Electric Materials Corporation Representative Patent Attorney Tatsuo Ito Representative Patent Attorney Tetsuya Ito No. 1 Figure 3 Figure 2 Figure 2 (Q) Figure 2 (b) Figure 4 $4 Figure (b)

Claims (1)

[Claims] 1. An AC power source, an inductance device, a discharge lamp that forms a first closed circuit together with the AC power source and the inductance device, and a discharge lamp that is turned on for a predetermined period in the first half of a half cycle of the AC power source and the inductance device. a switch device forming a second closed circuit together with the device, the energy stored in the inductance device by the second closed circuit during the ON period of the switch device is transferred to the inductance device during the subsequent OFF period of the switch device. In a discharge lamp lighting device that applies power to the discharge lamp superimposed on an AC power source, a second switch device is connected in series between the inductance device and the discharge lamp, and the inductance device and the second switch device are connected in series. A discharge lamp lighting device characterized in that a series circuit of an impedance element and a third switch which is controlled to be turned on and off alternately is connected to the second switch in parallel to the series circuit.