JPH09232093A - Lighting device for discharge lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a discharge lamp lighting device which can quickly light a discharge lamp. SOLUTION: At lighting start time of a discharge lamp 4, when first and second MOS-FETs 6 are repectively put in an ON condition and an OFF condition, a high voltage generating capacitor 11 is charged with DC input voltage of an AC converting circuit 3. Next, the first and the second MOS-FETs 6 and 7 are respectively switched to an OFF condition and an ON condition, a TRIAC 17 is put in an ON condition, and energy charged to a primary winding 12a of a high voltage generating transformer 12 through the TRIAC 17 from the high voltage generating capacitor 11 is released. Therefore, high tension pulse voltage is generated in a secondary winding 12b of the high voltage generating transformer 12 in a period in synchronism with an AC output frequency of the AC converting circuit 3. Therefore, since high tension pulse voltage is impressed on the discharge lamp 4 at initial impression time of AC output voltage in synchronism with AC output voltage of the AC converting circuit 3, the discharge lamp 4 can be quickly lighted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lighting device for a discharge lamp such as a metal halide lamp or a mercury lamp (HID lamp),
In particular, the present invention relates to a discharge lamp lighting device that shortens the time (quick start) before the discharge lamp starts lighting.

[0002]

2. Description of the Related Art A conventional discharge lamp lighting device, for example, as shown in FIG. 5, is composed of a commercial AC power source and a capacitor input type rectifying / smoothing circuit or a DC converter circuit for power factor correction and produces smooth DC power. A direct current power supply 1 to be generated, an alternating current conversion circuit (inverter) 3 connected to an output terminal of the direct current power supply 1 via an input side smoothing capacitor 2, and a discharge lamp 4 connected to an output terminal of the alternating current conversion circuit 3. The discharge lamp 4 is provided with a high-voltage pulse generation circuit 5 that generates a high-voltage pulse voltage applied to the discharge lamp 4 at the start of lighting. The AC conversion circuit 3 is configured by bridge-connecting first to fourth MOS-FETs (MOS field effect transistors) 6 to 9,
By alternately turning on / off the first and fourth MOS-FETs 6 and 9 and the second and third MOS-FETs 7 and 8, a connection point between the first and second MOS-FETs 6 and 7 and A rectangular wave AC voltage is generated from the connection point of the third and fourth MOS-FETs 8 and 9. First to fourth at this time
Drain-source voltage V _DS1 of MOS-FETs 6 to 9
Waveforms of V _DS4 to V _DS4 are shown in FIGS. FIG.
In (A) to (D), the first to fourth MOS-FETs 6 to
When the drain-source voltages V _{DS1 to} V _{DS4 of 9} are 0 V, the MOS-FET is in the on state, and when the voltage is high level, the MOS-FET is in the off state. In addition, the high voltage pulse generation circuit 5 includes the first and third MOS-FETs.
Connection point of 6 and 8 and second and fourth MOS-FETs 7 and 9
A series resistor 10 and a high-voltage generating capacitor 11 connected in series with the connection point of, and a primary winding 12a and a discharge lamp 4 connected in series to the connection point of the series resistor 10 and the high-voltage generating capacitor 11 High voltage generating transformer 12 having a secondary winding 12b connected thereto, and high voltage generating capacitor 11
And an NPN transistor 13 connected in series to the primary winding 12a of the high voltage generating transformer 12, a connection point of the series resistor 10 and a high voltage generating capacitor 11, and the NPN.
It is composed of a sidac (bidirectional two-terminal thyristor: SSS) 14 as a trigger element and a series resistor 15 connected in series with the base terminal of the transistor 13. As the discharge lamp 4, a discharge lamp having a discharge electrode such as a metal halide lamp or a mercury lamp (HID lamp) is used.

In the configuration shown in FIG. 5, a smooth DC voltage of about 300 V containing no ripple component is supplied from the DC power supply 1 to the DC input terminal of the AC conversion circuit 3, and the first and fourth MOS-FETs 6 and 9 are supplied. And second and third MOS-FE
When T7 and T8 are alternately turned on / off at the timings shown in FIGS. 6 (A) to 6 (D), a rectangular wave AC voltage is applied to the discharge lamp 4. At the same time, the input side smoothing capacitor 2 is charged, and the high voltage generating capacitor 11 in the high voltage pulse generating circuit 5 is gradually charged by the charging voltage of the input side smoothing capacitor 2 through the series resistor 10. When the charging voltage of the high-voltage generating capacitor 11 becomes equal to or higher than the breakover voltage of the sidac 14, the sidac 14 becomes conductive and a current flows through the series resistor 15 to the base terminal of the NPN-type transistor 13 to turn on the NPN-type transistor 13. Become. At this time, the high voltage generating capacitor 1
1. Primary winding 12a of transformer 12 for high voltage generation and NP
High voltage generating capacitor 1 through the path of N-type transistor 13
A discharge current of 1 flows, and a high-voltage pulse voltage of about 5 kV is generated in the secondary winding 12b of the high-voltage generating transformer 12. This high-voltage pulse voltage is superimposed on the rectangular wave AC voltage of the AC conversion circuit 3 and applied to the discharge lamp 4 several times over several seconds, and the discharge lamp 4 starts lighting. FIG. 7 shows the waveform of the voltage V _OUT across the discharge lamp 4 at this time. After the discharge lamp 4 starts to light up, the impedance of the discharge lamp 4 becomes low and the charging voltage of the high-voltage generating capacitor 11 becomes the breakover voltage of the sidac 14 or less, so that the sidac 14 is blocked and the NPN transistor 13 is turned on. It is turned off. As a result, the application of the high-voltage pulse voltage from the high-voltage pulse generation circuit 5 to the discharge lamp 4 is stopped, and thereafter, the rectangular-wave AC current of the AC conversion circuit 3 causes the rectangular-wave AC current to continue to flow in the discharge lamp 4, and the discharge lamp 4 The lighting state of No. 4 is maintained.

[0004]

The discharge lamp lighting device described above, however, has a drawback that the manufacturing cost rises because an expensive trigger element such as the sidac 14 is specially required. Further, due to variations in the electrical characteristics of the series resistor 10, the high-voltage generating capacitor 11, and the sidac 14, the high-voltage pulse voltage of the high-voltage pulse generating circuit 5 may fluctuate or the generation cycle may become irregular. Especially,
The discharge lamp 4 having a discharge electrode such as a metal halide lamp or a mercury lamp does not start lighting only by applying a single high-voltage pulse voltage. Therefore, a plurality of discharge lamps are discharged for several seconds until the discharge lamp 4 starts lighting. It is necessary to apply a high voltage pulse voltage. Further, since the discharge lamp 4 has a characteristic that the open voltage period after application of the high-voltage pulse voltage shown by symbol H in FIG. Fourth MOS-FET
The earliest possible time point during the 6 and 9 on periods is desirable.
Therefore, if the generation cycle of the high-voltage pulse voltage of the high-voltage pulse generation circuit 5 becomes irregular, the open voltage period H after application of the high-voltage pulse voltage varies as shown in FIG. 7, and the discharge lamp 4 starts lighting. There was a drawback that it took a long time.

Therefore, an object of the present invention is to provide a discharge lamp lighting device capable of quickly lighting a discharge lamp.

[0006]

A lighting device for a discharge lamp according to the present invention comprises a DC power source for generating smooth DC power, an AC conversion circuit connected to an output terminal of the DC power source, and an AC conversion circuit. A discharge lamp connected to the output terminal and a high-voltage pulse generation circuit that generates a high-voltage pulse voltage to be applied to the discharge lamp at the start of lighting of the discharge lamp are provided. In this discharge lamp lighting device, the high-voltage pulse generating circuit includes a high-voltage generating transformer having a primary winding and a secondary winding connected to the discharge lamp, and a primary winding of the high-voltage generating transformer. A switching element that is connected in series to the AC conversion circuit and is turned on when the AC output voltage of the AC conversion circuit is switched from one half cycle to the other half cycle, and the AC output voltage of the AC conversion circuit is one of The primary winding of the high-voltage generating transformer is charged by the DC input voltage of the AC conversion circuit in the half cycle and when the AC output voltage is switched from one half cycle to the other half cycle, through the switching element. A high voltage generating capacitor for discharging energy charged to a line, and the high voltage generating transformer of the high voltage generating circuit in a cycle synchronized with an AC output frequency of the AC conversion circuit.
The high voltage pulse voltage is output from the next winding.

At the start of lighting of the discharge lamp, when the AC output voltage of the AC conversion circuit is one half cycle, the DC input voltage of the AC conversion circuit charges the high voltage generating capacitor in the high voltage pulse generating circuit. Next, when the AC output voltage is switched from one half cycle to the other half cycle, the switching element in the high voltage pulse generation circuit is turned on, and the primary voltage of the high voltage generation transformer is passed from the high voltage generation capacitor through the switching element. The energy charged in the winding is released. At this time, a current flows through the primary winding of the high-voltage generating transformer to induce a high-voltage pulse voltage in the secondary winding, and this high-voltage pulse voltage is superimposed on the AC output voltage of the AC conversion circuit and applied to the discharge lamp. It Therefore, the high voltage pulse voltage is output from the secondary winding of the high voltage generating transformer in a cycle synchronized with the AC output frequency of the AC conversion circuit. As a result, since the high-voltage pulse voltage is applied to the discharge lamp at the initial application of the AC output voltage synchronized with the AC output voltage of the AC conversion circuit, the open voltage period after applying the high-voltage pulse voltage becomes longer, and the discharge lamp can be operated quickly. Can be turned on.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a lighting device for a discharge lamp according to the present invention will be described below with reference to FIGS.
However, in FIG. 1, portions substantially the same as the portions shown in FIG. 5 are denoted by the same reference numerals, and description thereof will be omitted. As shown in FIG. 1, the discharge lamp lighting device according to the present embodiment has a structure in which the first and second MOS-FETs 6 and 7 are connected in place of the high voltage pulse generation circuit 5 in the discharge lamp lighting device shown in FIG. A series resistor 10 and a discharge prevention diode 1 connected in series between the point and the connection point of the second and fourth MOS-FETs 7 and 9.
6, a high-voltage generating capacitor 11, a high-voltage generating transformer 12 having a primary winding 12a and a secondary winding 12b connected in series to the discharge lamp 4, and one and the other main terminals T ₁ , T ₂ Is a triac (bidirectional three-terminal thyristor: TR) as a switching element connected to the connection point between the discharge prevention diode 16 and the high-voltage generating capacitor 11 and the primary winding 12a of the high-voltage generating transformer 12, respectively.
IAC) 17, a trigger pulse forming resistor 18 connected between the gate terminal of the triac 17 and one of the main terminals T ₁ , and a series connection between the trigger pulse forming resistor 18 and the discharge prevention diode 16. A high-voltage pulse generation circuit 21 including a trigger pulse forming capacitor 19 and a backflow prevention diode 20 is provided. Therefore, in the high-voltage pulse generating circuit 21 shown in FIG. 1, the connection position of the series resistor 10 is different from that of the high-voltage pulse generating circuit 5 shown in FIG. 5, and the series circuit of the sidac 14 and the series resistor 15 and the NPN transistor 13 are provided. Omitted. Other configurations are substantially the same as those of the discharge lamp lighting device shown in FIG.

The operation of the discharge lamp lighting device shown in FIG. 1 will be described below. A smooth DC voltage of about 300 V that does not include a ripple component is supplied from the DC power supply 1 to the DC input terminal of the AC conversion circuit 3 through the input-side smoothing capacitor 2,
When the first and fourth MOS-FETs 6 and 9 and the second and third MOS-FETs 7 and 8 are alternately turned on and off at the timings shown in FIGS. 6A to 6D, the discharge lamp 4 A rectangular wave AC voltage is applied to. At the start of lighting of the discharge lamp 4, when the rectangular wave AC voltage of the AC conversion circuit 3 has a positive half cycle, the first MOS-FET 6 is in the ON state and the second MOS-
Assuming that the FET 7 is off, a current flows through the first MOS-FET 6, the series resistor 10 and the discharge prevention diode 16 due to the DC input voltage of the AC conversion circuit 3, and the high voltage generation capacitor in the high voltage pulse generation circuit 21. 11 is charged. After that, when the rectangular wave AC voltage of the AC conversion circuit 3 is switched from the positive half cycle to the negative half cycle, the first and second MOS-FETs 6 and 7 are turned from the ON state to the OFF state and from the OFF state to the ON state, respectively. In this state, the high voltage generating capacitor 11 to the triac 17,
Trigger pulse forming resistor 18, trigger pulse forming capacitor 19, backflow prevention diode 20, and series resistor 1
A current flows through the path of the second MOS-FET 7 through 0. At the same time, the voltage generated at both ends of the trigger pulse forming resistor 18 is applied to the gate terminal of the triac 17 to turn on the triac 17, and the primary voltage of the high voltage generating transformer 12 is passed from the high voltage generating capacitor 11 through the triac 17. The charged energy is discharged to the winding 12a. At this time, 1 of the transformer 12 for high voltage generation
A current flows through the secondary winding 12a and the secondary winding 12b has a positive polarity of 5
A high voltage pulse voltage of about kV is induced, and this high voltage pulse voltage is superimposed on the rectangular wave AC voltage of the AC conversion circuit 3 and applied to the discharge lamp 4. Therefore, as shown in FIG. 2, the rectangular wave AC voltage of the AC conversion circuit 3 is switched from the negative half cycle to the positive half cycle, that is, the first and fourth MOS-FETs 6 and 9 of the AC conversion circuit 3. A high voltage pulse voltage V _P is applied to the discharge lamp 4 at the time when both of them turn from the off state to the on state. The above operation is repeated for a few seconds before the discharge lamp 4 starts to be lit, so that the discharge lamp 4 can be operated at a cycle synchronized with the frequency of the rectangular wave AC output of the AC conversion circuit 3.
The high-voltage pulse voltage of about kV is applied multiple times, and the discharge lamp 4
Lights up. After starting the lighting of the discharge lamp 4, the discharge lamp 4
Since the impedance becomes low, almost no current flows through the high voltage generating capacitor 11 in the high voltage pulse generating circuit 21, and the voltage across both ends becomes approximately 0V. Therefore, no voltage is applied to the gate terminal of the triac 17, and the triac 17 is turned off. As a result, the application of the high-voltage pulse voltage from the high-voltage pulse generation circuit 21 to the discharge lamp 4 is stopped, and thereafter, the rectangular-wave AC current of the AC conversion circuit 3 causes the rectangular-wave AC current to continue to flow in the discharge lamp 4, and the discharge lamp 4 The lighting state of No. 4 is maintained.

As described above, in this embodiment, the high-voltage pulse voltage is applied to the discharge lamp 4 at the time of initial application of the rectangular-wave AC output voltage synchronized with the rectangular-wave AC output voltage of the AC conversion circuit 3. As shown in 2, the open voltage period H after application of the high-voltage pulse voltage V _P becomes long, and the discharge lamp 4 can be reliably turned on with a small number of high-voltage pulse voltages. Therefore, the discharge lamp 4 can be quickly turned on. Further, in the discharge lamp lighting device shown in FIG.
Since the triac 17 is used instead of the PN type transistor 13 and the sidac 14, it is possible to reduce the manufacturing cost of the discharge lamp lighting device by omitting an expensive and special trigger element such as a sidac. When the triac 17 can be reliably turned on at high speed, the trigger pulse forming resistor 18, the trigger pulse forming capacitor 19 and the backflow prevention diode 20 are omitted, and the gate terminal of the triac 17 is connected to the series resistor 10. Alternatively, it may be directly connected to the connection point of the discharge prevention diode 16.

The embodiment of the present invention is not limited to the above embodiment, and various modifications can be made. For example, in the discharge lamp lighting device of the embodiment shown in FIG. 3, one end of the primary winding 12a of the high voltage generating transformer 12 is connected to the connection point of the high voltage generating capacitor 11 and the discharge prevention diode 16,
The other end of the primary winding 12a of the transformer 12 for high voltage generation and the second
A thyristor (reverse blocking 3-terminal thyristor: SCR) 22 is connected as a switching element between the connection point of the fourth MOS-FETs 7 and 9 and a reverse conducting diode 23 is connected in antiparallel with the thyristor 22 and the triac 17 is connected. the connected gate terminals and one of the main terminals T ₁ at both ends of the discharge preventing diode 16, high-voltage pulse generating other main terminal T ₂ of the triac 17 is connected to the gate terminal of the thyristor 22 through a series resistor 15 The circuit 21 is configured. Other configurations are substantially the same as those of the discharge lamp lighting device shown in FIG. In the circuit of FIG. 3, the first and second MOS
-When the FETs 6 and 7 are turned off and turned on respectively, the triac 17 is turned on, current flows from the triac 17 to the gate terminal of the thyristor 22 through the series resistor 15, and the thyristor 22 is turned on. At this time, the primary winding 12 of the transformer 12 for high voltage generation
A current flows through a, a high-voltage pulse voltage is induced in the secondary winding 12b, and it is superimposed on the rectangular wave AC voltage of the AC conversion circuit 3.
As a result, the high voltage pulse voltage is applied to the discharge lamp 4 in a cycle synchronized with the AC output frequency of the AC conversion circuit 3. Therefore, also in the embodiment shown in FIG. 3, the discharge lamp 4 can be quickly turned on as in the embodiment shown in FIG. The discharge lamp lighting device shown in FIG. 3 differs from the conventional discharge lamp lighting device shown in FIG. 5 in that the connection position of one end of the series resistor 10 is changed from the connection point of the first and third MOS-FETs 6 and 8. The connection point of the first and second MOS-FETs 6 and 7 is changed to a series resistor 10 and a high voltage generating capacitor 11
A discharge prevention diode 16 is inserted between the sidac 1
Since the 4 and NPN type transistors 13 are replaced with the triac 17 and the thyristor 22, respectively, there is an advantage that the conventional lighting device for a discharge lamp can be easily modified as compared with the case of FIG.

The discharge lamp lighting device of the embodiment shown in FIG. 4 is obtained by replacing the triac 17 in the discharge lamp lighting device shown in FIG. 3 with a PNP transistor 24. Therefore, also in the embodiment shown in FIG.
Since a circuit operation similar to that of the embodiment shown in FIG. 3 is performed, the discharge lamp 4 can be quickly turned on as in the embodiment shown in FIG. In particular, in the embodiment shown in FIG. 4, since the PNP transistor 24, which is cheaper than the triac 17, is used, there is an advantage that the manufacturing cost of the discharge lamp lighting device can be further reduced as compared with the embodiment shown in FIG. is there.

In each of the above embodiments, the AC conversion circuit 3 is an example of a so-called full-bridge type inverter in which four MOS-FETs 6 to 9 are bridge-connected. However, for example, third and fourth MOS- The FETs 8 and 9 may be replaced by capacitors to form a half-bridge type inverter. The parallel circuit of the thyristor 22 and the reverse conducting diode 23 in the embodiment shown in FIGS. 3 and 4 may be replaced with a reverse conducting 3-terminal thyristor to further simplify the circuit configuration. In addition, each MOS-FE of the AC conversion circuit 3
Instead of T6 to 9, other switching elements such as a bipolar transistor, a junction field effect transistor (J-FET) or a reverse blocking three-terminal thyristor (SCR) may be used. Furthermore, the application time of the high-voltage pulse voltage to the discharge lamp 4 is not limited to the initial application time of the AC output voltage, and may be applied with a slight delay.

[0014]

According to the present invention, since the high-voltage pulse voltage is applied to the discharge lamp at the initial application of the AC output voltage synchronized with the AC output voltage of the AC conversion circuit, it is possible to start lighting the discharge lamp. It is possible to shorten the time and quickly turn on the discharge lamp (quick start). Further, since an expensive trigger element such as a sidac which is required in the conventional discharge lamp lighting device is not required, the manufacturing cost of the discharge lamp lighting device can be reduced.

[Brief description of drawings]

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

FIG. 2 is a waveform diagram showing the voltage across the discharge lamp shown in FIG. 1 at the start of lighting.

FIG. 3 is an electric circuit diagram showing a modified embodiment of the discharge lamp lighting device of FIG.

FIG. 4 is an electric circuit diagram showing a modified embodiment of the discharge lamp lighting device of FIG.

FIG. 5 is an electric circuit diagram showing a conventional lighting device for a discharge lamp.

FIG. 6 is a waveform diagram showing the drain-source voltage of each MOS-FET in FIGS. 1 and 5.

FIG. 7 is a waveform diagram showing the voltage across the discharge lamp shown in FIG. 5 at the start of lighting.

[Explanation of symbols]

1. . . DC power supply, 2. . . Input side smoothing capacitor,
3. . . AC conversion circuit, 4. . . Discharge lamps, 5, 2
1. . . High-voltage pulse generation circuit, 6-9. . . First to fourth
MOS-FET, 10, 15. . . Series resistance, 1
1. . . High voltage generating capacitor, 12. . . Transformer for high voltage, 12a. . . Primary winding, 12b. . . Secondary winding, 13. . . NPN type transistor, 14. . . Sidac (trigger element), 16. . . Discharge prevention diode, 17. . . Triac (switching element), 1
8. . . Trigger pulse forming resistor, 19. . . A capacitor for forming a trigger pulse, 20. . . Backflow prevention diode, 22. . . Thyristor (switching element), 2
3. . . Reverse conducting diode, 24. . . PNP type transistor

Claims (1)

[Claims] 1. A DC power source for generating smooth DC power,
An AC conversion circuit connected to the output terminal of the DC power supply, a discharge lamp connected to the output terminal of the AC conversion circuit, and a high voltage that generates a high-voltage pulse voltage applied to the discharge lamp at the start of lighting of the discharge lamp. In a discharge lamp lighting device including a pulse generation circuit, the high-voltage pulse generation circuit includes a high-voltage generation transformer having a primary winding and a secondary winding connected to the discharge lamp, and the high-voltage generation transformer. A switching element that is connected in series to the primary winding of the AC conversion circuit and is turned on when the AC output voltage of the AC conversion circuit is switched from one half cycle to the other half cycle; When the AC output voltage is one half cycle, it is charged by the DC input voltage of the AC conversion circuit, and when the AC output voltage is switched from one half cycle to the other half cycle, the switch A high voltage generating capacitor for discharging the energy charged to the primary winding of the high voltage generating transformer through a switching element, and the high voltage generating transformer having a high voltage generating cycle in synchronization with the AC output frequency of the AC conversion circuit. A lighting device for a discharge lamp, wherein the high voltage pulse voltage is output from a secondary winding.