JPH01298686A - Ignitor for high-voltage electric-discharge lamp - Google Patents

Abstract

PURPOSE:To enable the instantaneous restart just after putting out without reducing the lives of a high-voltage electric-discharge lamp and a two-terminal discharge gas by providing current control means in a DC-DC converter, increasing the output current after inputting a power source, and controlling the charging voltage gradient of a charging circuit. CONSTITUTION:When a power source is inputted, the output current of a DC-DC converter 5 is returned, the on duty of a transistor 11 is controlled by a pulse length modulator 22 in a current control means 13, and the capacitor 6a in a charging circuit 6 is charged according to the charging voltage gradient increased by the output current increased with the lapse of time. The high-voltage pulse by the discharge current through a two-terminal discharge gap 7 based on this charging voltage is supplied to a high-voltage electric-discharge lamp. Thus, the generation period corresponding to the generation density of high-voltage pulse is shortened with the lapse of time, the stress afforded to the high-voltage electric-discharge lamp electrode at the initial starting is reduced, and the restart is instantaneously conducted without damaging the gap 7 by the high-voltage pulse of the same number. Thus, the instantaneous restart after putting out can be carried out without reducing the lives of the high- voltage electric-discharge lamp and the terminal discharge gap.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention relates to an igniter for a high-pressure discharge lamp that applies a high-voltage pulse for starting to a high-pressure discharge lamp to light the high-pressure discharge lamp. The present invention relates to an igniter for a high-pressure discharge lamp that can instantaneously restart a high-pressure discharge lamp.

[Conventional technology]

A conventional high-pressure discharge lamp igniter that applies a high-voltage pulse for starting a high-pressure discharge lamp connected to a power supply via an inductive ballast is supplied with a high-voltage generation circuit and the output of this high-voltage generation circuit. A charging circuit, a two-terminal discharge gap to which the output voltage of this charging circuit is applied, and a two-terminal discharge gap from the charging circuit.
A step-up transformer has a primary winding inserted in series in the current-carrying path to the terminal discharge gap, and a secondary winding inserted in series in the current-carrying path from the power supply to the high-pressure discharge lamp, and the secondary winding of the step-up transformer. It consists of a bypass capacitor that applies the induced voltage across the high-pressure discharge lamp by bypassing the inductive ballast (as disclosed in Japanese Patent Application No. 62-326328 as a conventional example).

In this igniter for high-pressure discharge lamps, when the output voltage of the charging circuit that is charged by the output voltage of the high-voltage generating circuit exceeds the discharge starting voltage of the two-terminal discharge gap, the charge of the charging circuit is transferred to the primary winding of the step-up transformer. is rapidly discharged through the transformer, inducing a high voltage pulse in the secondary winding of the step-up transformer. This high-voltage pulse is then applied to the high-pressure discharge lamp through the bypass capacitor, and as a result, the high-pressure discharge lamp starts and lights up.

In this case, the voltage required to start the high-pressure discharge lamp is several KV at the initial start-up, for example 1 to 1 KV per half cycle of the commercial power supply voltage as shown in
It is sufficient to generate two, but if you want to restart the lights instantly immediately after the lights go out, it is several tens of KV, and the fourth
As shown in Figure (bl), for example, it is necessary to repeatedly generate 10 to several dozen high voltage pulses per half cycle of the commercial power supply voltage.

For this reason, the above-mentioned high-pressure discharge lamp igniter, which is intended to instantly restart the high-pressure discharge lamp immediately after extinguishing, sends out several dozen high-voltage pulses of several tens of KV per half cycle of the commercial power supply voltage. The circuit is designed to generate this.

[Problem to be solved by the invention]

As mentioned above, when a high-pressure discharge lamp igniter whose circuit is designed to generate several tens of KVO high-voltage pulses within a half cycle of the commercial power supply voltage is used to start a high-pressure discharge lamp, a high-pressure discharge occurs at the initial startup. There is a problem in that the number of high voltage pulses applied to the lamp becomes excessive, and excessive stress is applied to the high pressure discharge lamp, resulting in an extremely shortened life span of the high pressure discharge lamp. Also, 2
There was a problem in that the number of discharges in the terminal discharge gap also increased, and the life of the 2#A child discharge gap also became short.

An object of the present invention is to provide an igniter for a high-pressure discharge lamp that can instantly restart a high-pressure discharge lamp immediately after extinguishing the lamp without shortening the life of the high-pressure discharge lamp or the life of the two-terminal discharge gap. be.

[Means to solve the problem]

The igniter for a high pressure discharge lamp of the present invention applies a high voltage pulse for starting to a high pressure discharge lamp connected to a power source via an inductive ballast.

The igniter for a high pressure discharge lamp includes a DC-DC converter, a charging circuit that is charged with the output current of the DC-DC converter, a two-terminal discharge gap to which the charging voltage of the charging circuit is applied, and a charging circuit. A step-up transformer has a primary winding inserted in series in the current-carrying path from the power supply to the two-terminal discharge gap, and a secondary winding inserted in series in the current-carrying path from the power source to the high-pressure discharge lamp, and the secondary winding of the step-up transformer. and a bypass capacitor for applying the voltage induced in the line across the high-pressure discharge lamp by bypassing the inductive ballast,
DC-D is a current control means that gradually increases the rising slope of the charging circuit's charging pressure by increasing the output current of the DC-DC converter as time passes after the power is turned on.
It is installed in the C converter.

In addition, instead of the above-mentioned current control means, by reducing the output current of the DC-DC converter at the initial start-up of the high-pressure discharge lamp, the rising slope of the charging voltage of the charging circuit can be reduced (and at the same time, when the high-pressure discharge lamp is restarted, the - DC-DC current control means that increases the rising slope of the charging voltage of the charging circuit by increasing the output current of the DC converter.
It may also be provided in the converter.

[For production]

In the configuration of the present invention, the charging circuit is charged with the output current of the DC-DC converter, and when the charging voltage of the charging circuit exceeds the discharge start voltage of the two-terminal discharge gap, the charged charge of the charging circuit is transferred to the primary winding of the step-up transformer. The battery is rapidly discharged through the wire, and thereafter the charging and discharging operations of the charging circuit are repeated. Each time the charge in the charging circuit is discharged, a high voltage pulse is generated in the secondary winding of the step-up transformer, and this high voltage pulse is applied to the high-pressure discharge lamp through the bypass capacitor, starting the high-pressure discharge lamp. Then it turns on.

At this time, the current control means increases the output current of the DC-DC converter as time passes after the power is turned on. As a result, the charging speed of the charging circuit, that is, the rising slope of the charging voltage of the charging circuit becomes larger as time passes, and the time it takes for the charging voltage of the charging circuit to exceed the discharge starting voltage of the two-terminal discharge gap from a state of zero increases. Therefore, the discharge interval of the two-terminal discharge gap becomes shorter. As a result,
The generation cycle of the high voltage pulses applied to the high pressure discharge lamp gradually becomes shorter.

Therefore, during initial startup, when the high-pressure discharge lamp has a long generation cycle of high-voltage pulses immediately after the power is turned on,
That is, it starts and lights up when the high voltage pulse generation density is low. On the other hand, restarting, which is difficult to start, occurs when a period of time has passed after the high-pressure discharge lamp was powered on, and the high-voltage pulse generation period has shortened to the point where it can be started, that is, the generation density of high-voltage pulses has decreased to the point where it can be started. When it increases to a certain point, it starts and lights up. Note that the period during which the generation cycle of the high-voltage pulse changes is extremely short compared to the period from when the high-pressure discharge lamp is turned off until the high-pressure discharge lamp cools down.

This igniter for high-pressure discharge lamps can start and light the high-pressure discharge lamp in a state where the high-voltage pulse generation period is long and the high-voltage pulse generation density is low during the initial startup. The stress on the electrodes can be reduced, the life of the high-pressure discharge lamp will not be shortened, and the life of the two-terminal discharge gap will not be shortened.Furthermore, when restarting, the generation cycle of high-voltage pulses can be reduced. Increases the generation density of short, high-voltage pulses (
This allows the high-pressure discharge lamp to be instantly restarted immediately after it has been turned off. Also, during this restart, no more high-voltage pulses than necessary are applied, and no excessive stress is applied to the high-pressure discharge lamp. will not be shortened.

Another current control means reduces the output current of the DC-DC converter during initial startup of the high-pressure discharge lamp. As a result, at the initial start-up of the high-pressure discharge lamp, the rising slope of the charging voltage of the charging circuit is small, and the discharge interval of the two-terminal discharge gap becomes long. On the other hand, when restarting the high-pressure discharge lamp, the output current of the DC-DC converter is increased. As a result, when the high-pressure discharge lamp is restarted, the rising slope of the charging voltage of the charging circuit is large, and the discharge interval of the two-terminal discharge gap is shortened.

Therefore, at the time of initial startup, when the lamp is easy to start, the high-pressure discharge lamp starts and lights up in a state where the high-voltage pulse generation period is long, that is, the high-voltage pulse generation density is low.

On the other hand, when restarting the lamp, which is difficult to start, the high-pressure discharge lamp starts and lights up in a state where the high-voltage pulse generation cycle is long, that is, the high-voltage pulse generation density is high.

In this igniter for high-pressure discharge lamps, at the time of initial startup, the generation cycle of high-voltage pulses is lengthened and the generation density of high-voltage pulses is lowered, making it possible to reduce stress on the electrodes of the high-pressure discharge lamp. , does not shorten the life of the high-pressure discharge lamp, nor does it shorten the life of the two-terminal discharge gap.Moreover, when restarting the high-pressure discharge lamp, the high-voltage pulse generation cycle is shortened and the high-voltage pulse is Since the generation density of is increased, the high-pressure discharge lamp can be instantly restarted immediately after extinguishing.

〔Example〕

A first embodiment of the present invention will be described based on FIGS. 1 to 9. That is, as shown in FIG. 1, this igniter for a high-pressure discharge lamp uses, for example, a commercial AC power source (DC power source, high frequency power source).

A high-voltage pulse for starting is applied to a high-pressure discharge lamp 3 connected to a rectangular wave power source 1 via an inductive ballast 2.

This high-pressure discharge lamp igniter includes a charging circuit 6 consisting of a DC power supply 4, a DC-DC converter 5 supplied with power from the DC power supply 4, and a capacitor 6a charged with the output current of the DC-DC converter 5. and a two-terminal discharge gap 7 to which the charging voltage of this charging circuit 6 is applied.
A step-up transformer in which a primary winding n1 is inserted in series in the current-carrying path from the charging circuit 6 to the two-terminal discharge gap 7, and a secondary winding nt is inserted in series in the current-carrying path from the power source 1 to the high-pressure discharge lamp 3. 8 and a bypass capacitor 9 for applying the induced voltage of the secondary winding n2 of the step-up transformer 8 across the high-pressure discharge lamp 3, bypassing the inductive ballast 2, and At the same time, by increasing the output current of the DC-DC converter 5, the charging circuit 6
The DC-DC converter 5 is provided with current control means (not shown) for gradually increasing the rising slope of the charging voltage.

In this igniter for a high-pressure discharge lamp, the capacitor 6a of the charging circuit 6 is charged with the output current of the DC-DC converter 5, and when the charging voltage of the charging circuit 6 exceeds the discharge starting voltage of the two-terminal discharge gap 7, the charging circuit 6 is rapidly discharged through the primary winding n1 of the step-up transformer 8, and thereafter the charging and discharging operations of the charging circuit 6 are repeated. Then, every time the charge in the charging circuit 6 is discharged, the secondary winding n! of the step-up transformer 8! A high voltage pulse is generated, and this high voltage pulse is applied to the high pressure discharge lamp 3 through the bypass capacitor 9, and the high pressure discharge lamp 3 starts and lights up.

At this time, the current control means increases the output current of the DC-DC converter 5 as time passes after the power source 1 is turned on. As a result, the charging speed of the charging circuit 6, that is, the rising slope of the charging voltage of the charging circuit 6 increases over time, and the charging voltage of the charging circuit 6 exceeds the discharge starting voltage of the two-terminal discharge gap 7 from a zero state. time will be shorter. As a result, the generation cycle of the high voltage pulses applied to the high pressure discharge lamp 3 gradually becomes shorter.

Therefore, at the time of initial starting, which is easy to start, the high-pressure discharge lamp 3 starts and lights up when the high-voltage pulse generation cycle is long immediately after the power is turned on, that is, when the high-voltage pulse generation density is low. On the other hand, when the high-pressure discharge lamp 3 is restarted, which is difficult to start, when time has passed since the high-pressure discharge lamp 3 was turned on and the generation cycle of high-voltage pulses has shortened to a point where starting is possible, that is, the generation density of high-voltage pulses has decreased. When the amount increases to a point where it can be started, it starts and lights up. Note that the period during which the generation cycle of the high-voltage pulse changes is extremely short compared to the time from when the high-pressure discharge lamp 3 is turned off until the high-pressure discharge lamp 3 cools down.

In this igniter for a high-pressure discharge lamp, the high-pressure discharge lamp 3 can be started and lit in a state where the generation period of high-voltage pulses is long and the generation density of high-voltage pulses is low at the time of initial startup. It is possible to reduce stress on the electrodes of high pressure discharge lamp 3.
The life of the two-terminal discharge gap 7 will not be shortened, and the life of the two-terminal discharge gap 7 will not be shortened.Moreover, when restarting, the high voltage pulse generation period is short and the high voltage pulse generation density can be increased. The high-pressure discharge lamp 3 is turned on immediately after turning off.
can be restarted instantly. Also, at this time of restarting, no more high voltage pulses than necessary for starting are applied, and no excessive stress is applied to the high pressure discharge lamp 3 at this time as well. The life of lamp 3 will not be shortened.

Below, this igniter for high pressure discharge lamp is shown in Figures 1 to 9.
This will be explained in detail based on the figures.

First, the basic operation of this igniter for a high pressure discharge lamp will be explained with reference to FIGS. 1 to 3. In addition, Figure 2 is D
A specific circuit example of the C-DC converter 5 is shown, in which 11 is a switching transistor, 12 is a flyback transformer, 13 is an oscillation drive circuit, and 14 is a rectifying diode. FIG. 3 is a time chart of each part of FIG. 2.

In this igniter for a high pressure discharge lamp, a transistor 11 is switched by an oscillation drive circuit 13 in a DC-DC converter 5.

When the transistor 11 is on (between to and 1.), a gradually increasing current 11 flows through the primary winding of the flyback transformer 12 as shown in FIG. Due to this current I, energy E of E-+ALpIF'' is accumulated in the primary S line of the flyback transformer 12. However, L is the inductance of the primary winding of the flyback transformer 12, ■ is the time t, is the value of current 11 at .

When the transistor 11 turns off at time t, the energy stored in the flyback transformer 12 begins to be released, and a current I! gradually decreases in the secondary winding of the flyback transformer 12.
flows, the capacitor 6a of the charging circuit 6 is charged, and the current I! During the period when V is flowing, the voltage Ve across the capacitor 6a
l gradually increases as shown in FIG. 3 fcl, and remains constant for the rest of the period.

Thereafter, the transistor 11 remains off until time t, and at time t, the transistor 11 is turned on again, repeating the same operation as that from time t1. As a result, each time the transistor 11 is turned on and off, the voltage VCI across the capacitor 6a increases as shown in FIG.
It will rise as shown in C).

The voltage VCI across the capacitor 6a is the discharge starting voltage (■) of the two-terminal discharge gap 7. When the voltage VCI is exceeded, the two-terminal discharge gap 7 is discharged by the voltage VCI across the capacitor 6a. Due to this two-terminal discharge gap 7, the charge accumulated in the capacitor 6a is rapidly discharged through the primary winding n of the step-up transformer 8, and at this time, the voltage between both ends of the secondary wire n8 of the step-up transformer 8 is shown in FIG. A high voltage pulse vP as shown by fdl is generated, and this high voltage pulse 2 is applied across the high pressure discharge lamp 3 through the bypass capacitor 9, and the high pressure discharge lamp 3 starts and lights up.

After the high pressure discharge lamp 3 lights up, the DC power supply 4
The output current of the DC-DC converter 5 is reduced by lowering the voltage of the oscillation drive circuit 13 or stopping the operation of the oscillation drive circuit 13, thereby preventing the high voltage pulse vP shown in FIG. 3 fdl from occurring.

In this case, for example, if the DC power source 4 is obtained by rectifying the voltage across the bypass capacitor 9, the voltage across the bypass capacitor 9 will automatically decrease when the high-pressure discharge lamp 3 is turned on, so the high-pressure discharge lamp Figure 3 + is automatically detected without the need for special means to detect the
It is possible to stop the generation of the high voltage pulse (2) of di.

By the way, when starting the high-pressure discharge lamp 3, as described in the explanation of the conventional example, in the case of initial starting, the method shown in FIG.
If one or two high voltage pulses V are applied to the high pressure discharge lamp 3 per half cycle of the commercial IT power supply voltage 50760b) as shown in a), the high pressure discharge lamp 3 can be sufficiently started.

However, in the case of a restart, 1 per half cycle of the commercial power supply voltage (50/60) 1z as shown in Figure 4 (bl)
It is necessary to apply zero to several tens of high voltage pulses (2) to the high pressure discharge lamp 3. In addition, Fig. 4 (8).

The sine wave at the top (peak) indicates the waveform of the voltage V of the power supply 1.

Therefore, in this embodiment, as described above, D
The C-DC converter 5 is provided with current control means.

This current control means, as shown in FIG. 5, generates a high voltage pulse V every half cycle of the voltage v0 of the electric voltage v0.

The number of objects is increased over time. For this purpose, the current control means increases the output current of the DC-DC converter 5 with the passage of time after turning on the power source 1, thereby increasing the output current of the capacitor 6a of the charging circuit 6.
The discharge interval of the two-terminal discharge gap 7 is shortened by gradually increasing the rising slope of the voltage Vel across the two terminals.

As described above, if the number of high-voltage pulses V per half cycle of the voltage V of the power supply 1 is increased over time, in the initial starting state when the high-pressure discharge lamp 3 is sufficiently cooled, , the high-pressure discharge lamp 3 starts and lights up in the first few cycles after the power is turned on (a period in which the number of pulses per half cycle is small), and then the high-voltage pulse V,
occurrence is stopped.

When restarting, when the number of high-voltage pulses VP per half cycle of the voltage v0 of the power supply 1 reaches the number determined depending on the degree of cooling of the high-pressure discharge lamp 3, it starts and lights up, and then the high-voltage pulses The generation of V is stopped.

As a result, an excessive number of high-voltage pulses vP are not applied to the high-pressure discharge lamp 3 not only at the time of initial startup but also at the time of restart.

FIG. 6 is a time chart illustrating the relationship between the rising slope of the charging voltage of the capacitor 6a and the interval between high voltage pulses Vp applied to the high pressure discharge lamp 3. From FIG. 6, it can be seen that the rising slope of the voltage VC+ across the capacitor 6a is fa
It is clear that when the state changes from the state t to the state shown in FIG. 6(1)), the interval between the high voltage pulses V becomes shorter as shown in FIG. 6(d) from fcl in FIG.

Next, specific means for increasing the rising slope of the charging voltage of the capacitor 6a of the charging circuit 6 will be explained.

Possible means for this include, for example, means for increasing the on-duty of the transistor 11 and means for lowering the switching frequency of the transistor 11.

FIG. 7 shows a specific circuit configuration for increasing the on-duty of the transistor 11 over time.

In the circuit shown in FIG. 7, the oscillation drive circuit 13 is composed of an oscillator 21, a pulse width modulator 22, and a feedback amplifier 23.

The oscillator 21 generates a triangular wave or a sawtooth wave, and supplies this triangular wave or sawtooth wave to the pulse width modulator 22. In addition, the feedback amplifier 23 has voltages ■,
The error voltage between the reference voltage VD and the reference voltage VD is amplified and the output voltage is provided to the pulse width modulator 22. As a result, pulse width modulator 22 generates a square wave synchronized with the output of oscillator 21. At this time, the pulse width of the square wave varies depending on the height of the output voltage of the feedback amplifier 23.

With this operation, the pulse width is narrowed when the voltage V is high, and the pulse width is widened when the voltage vR is low.

In this embodiment, by using a CR circuit etc.,
As shown in FIG. 8 [a], the voltage vlI is lowered as time passes after the power is turned on, thereby changing the pulse width of the square wave output from the pulse width modulator 22 as shown in FIG. 8 (bl). As a result, as mentioned above, the transistor 11
The on-duty increases over time. Therefore, the rising slope of the voltage VC+ across the capacitor 6a gradually increases, and the density of high voltage pulses applied to the high pressure discharge lamp 3 increases.

On the other hand, as a configuration for lowering the switching frequency of the transistor 11, the pulse width modulator 22 in FIG. This can also be achieved by supplying.

With this configuration, if the value of the voltage ■ is continuously changed from high to low over time, the voltage -
The output frequency of the frequency converter decreases continuously. Thereby, the generation density of high voltage pulses applied to the high pressure discharge lamp 3 can be gradually increased.

In addition, in the igniter for a high-pressure discharge lamp of this embodiment, as the on-duty of the transistor 11 is increased as shown in FIG. However, when the density exceeds a certain value, the two-terminal discharge gap 7! J<sustained discharge occurs, and the discharge starting voltage decreases.

As a result, when the generation density of high voltage pulses v2 exceeds a certain value, the voltage value of high voltage pulses V is automatically reduced.

Therefore, when the high-pressure discharge lamp is at the end of its service life and does not light up, or when there is no load, the voltage value of the high-voltage pulse (■) automatically decreases after a predetermined time has passed after the power is turned on.
It is highly safe and has a simple configuration because it does not require a lamp life detection circuit or a no-load detection circuit.

A second embodiment of the invention will be described based on FIG. 10. As shown in FIG. 10, this high-pressure discharge lamp igniter includes, in place of the current control means in the first embodiment,
By reducing the output current of the DC-DC converter 5 at the initial start-up of the high-pressure discharge lamp 3, the rising slope of the charging voltage of the charging circuit 6 is reduced, and the discharge interval of the two-terminal discharge gap 7 is lengthened, and the high-pressure discharge lamp 3 By increasing the output current of the DC-DC converter 5 when restarting the charging circuit 6, charging I! Increasing the rising slope of the voltage 2
The DC-DC converter 5 is provided with current control means for shortening the discharge interval of the terminal discharge gap 7.

In this igniter for a high-pressure discharge lamp, the current control means reduces the output current of the DC-DC converter 5 when the high-pressure discharge lamp 3 is initially started.

As a result, when the high-pressure discharge lamp 3 is initially started, the rising slope of the charging voltage of the charging circuit 6 is small, and the discharge interval of the two-terminal discharge gap 7 is long. The output 1 current of the converter 5 is increased.As a result, when the high-pressure discharge lamp 3 is restarted, the rising slope of the charging voltage of the charging circuit 6 is large, and the discharge interval of the two-terminal discharge gap 7 is shortened.

Therefore, at the time of initial starting, which is easy to start, the high-pressure discharge lamp 3 starts and lights up in a state where the high voltage pulse generation period is long, that is, the high voltage pulse generation density is low. On the other hand, at the time of restarting, which is difficult to start, the high-pressure discharge lamp 3 starts and lights up in a state where the high-voltage pulse generation period is long, that is, the high-voltage pulse generation density is high.

This igniter for high-pressure discharge lamps lengthens the generation cycle of high-voltage pulses and lowers the generation density of high-voltage pulses at the time of initial startup, so it is possible to reduce stress on the electrodes of the high-pressure discharge lamp 3. , does not shorten the life of the high pressure discharge lamp 3, nor does it shorten the life of the two-terminal discharge gap 7.
When restarting, the generation period of high voltage pulses is shortened to increase the generation density of high voltage pulses, so that the high pressure discharge lamp 3 can be instantaneously restarted immediately after extinguishing.

As mentioned above, in order to lower the generation density of high voltage pulses at the initial start and increase the generation density of high voltage pulses at the time of restart, it is necessary to increase the voltage The pulse width of the output of the pulse width modulator 22 can be narrowed, and the pulse width of the output of the pulse width modulator 22 can be widened by decreasing it at the time of restarting. This can be carried out based on the temperature level in step 3.

In this way, the voltage V is determined based on the temperature of the high pressure discharge lamp 3.
For example, a circuit as shown in FIG. 10 can be considered as a circuit for changing . This circuit has a configuration in which the voltage of a DC power supply 31 is divided by a series circuit of a resistor 32 and a negative characteristic thermistor 33 installed near the high pressure discharge lamp 3, and the voltage across the negative characteristic thermistor 33 is smoothed by a capacitor 34. realizable. In this circuit, when the temperature of the high-pressure discharge lamp 3 is low, that is, at the time of initial startup, the resistance value of the negative characteristic thermistor 33 is large and the voltage v3 is high, and when the temperature of the high-pressure discharge lamp 3 is high, that is, at the time of restarting, , the resistance value of the negative characteristic thermistor 33 is small, and the voltage V becomes low.

When this voltage V is input to the feedback amplifier 23 shown in FIG. 7, the density of high voltage pulse generation can be set to an optimal value depending on the state of the high pressure discharge lamp 3 (initial starting state, restarting state). can.

Note that, in order to change the generation density of high voltage pulses between the initial starting and restarting of the high-pressure discharge lamp 3, the oscillation frequency of the transistor 11 is set high at the initial starting and restarted, as described in the first embodiment. It may be set low at the time of starting.

Note that if the negative characteristic thermistor 33 is configured so that its temperature does not only rise due to the heat generated by the high-pressure discharge lamp 30, but also due to self-heating due to the energization of the negative characteristic thermistor 33, the power can be turned on even at the initial startup. After that, the density of high voltage pulse generation gradually increases. Therefore, even when the high-pressure discharge lamp reaches the end of its life and becomes difficult to start, the high-pressure discharge lamp 3 can be reliably started.

The rest is the same as the first embodiment.

〔Effect of the invention〕

According to the igniter for a high-pressure discharge lamp of the present invention, by increasing the output current of the DC-DC converter as time passes after the in is turned on, the rising slope of the charging voltage of the charging circuit is increased, and the two-terminal discharge gap is discharged. Since a DC-DC converter input control means for shortening the interval is provided, at the time of initial startup, the high-pressure discharge lamp can be started and lit with a long high-voltage pulse generation period and a low high-voltage pulse generation density. of high-pressure discharge lamps during initial startup?
The stress on the fiFi can be reduced and the life of the high pressure discharge lamp will not be shortened. Moreover, when restarting, the high voltage pulse generation period is short and the high voltage pulse generation density can be increased, and the high pressure discharge lamp can be instantly restarted immediately after extinguishing. Also, during this restart, no more high-voltage pulses than are necessary for starting are applied, and no excessive stress is applied to the high-pressure discharge lamp. It does not shorten the life of the discharge lamp.

On the other hand, instead of the above DC-DC converter control means,
By reducing the output current of the DC-DC converter at the initial start-up of the high-pressure discharge lamp, the rising slope of the charging voltage of the charging circuit is reduced and the discharge interval of the two-terminal discharge gap is lengthened. -D
In a device equipped with a DC-DC converter input control means that shortens the discharge interval of the two-terminal discharge gap by increasing the rising slope of the charging voltage of the charging circuit by increasing the output current of the C converter, the high Since the generation period of voltage pulses is lengthened and the generation density of high voltage pulses is lowered, the stress applied to the electrodes of the high pressure discharge lamp can be reduced, and the life of the high pressure discharge lamp will not be shortened. When restarting the high-pressure discharge lamp, the high-voltage pulse generation period is shortened to increase the high-voltage pulse generation density, so the high-pressure discharge lamp can be instantly restarted immediately after extinguishing.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing the configuration of a first practical example of the present invention, FIG. 2 is a circuit diagram showing the specific configuration of the main part of FIG. 1, and FIG.
The figure is a time chart showing the operation of the circuit in Fig. 2, Fig. 4 is a waveform chart showing the number of high voltage pulses required at initial start and restart, and Fig. 5 is a high voltage pulse that occurs in the first embodiment. A waveform diagram of voltage pulses, Figure 6 is a waveform diagram showing the charging speed of the charging circuit and the generation interval of high voltage pulses, and Figure 7 is a waveform diagram of the second
8 and 9 are time charts showing the operation of the circuit in FIG. 7. FIG. 10 is a circuit diagram showing the configuration of the second embodiment of the present invention. FIG. DESCRIPTION OF SYMBOLS 1... Power supply, 2... Inductive ballast, 3... High pressure discharge lamp, 5... DC-DC converter, 6... Charging circuit, 7... 2-terminal discharge gap, 8... ...Step-up transformer, 9... Bypass capacitor 1 - Power supply 6 - χ Zero circuit Fig. 3 (a) (b) Fig. 5 Fig. 6 Fig. 7 - Time → B change Fig. 8

Claims (2)

[Claims] (1) An igniter for a high-pressure discharge lamp that applies a high-voltage pulse for starting a high-pressure discharge lamp connected to a power source via an inductive ballast, comprising a DC-DC converter and an output current of the DC-DC converter. A charging circuit that is charged with a charging circuit, a two-terminal discharge gap to which a charging voltage of the charging circuit is applied, and a primary winding inserted in series in a current-carrying path from the charging circuit to the two-terminal discharge gap, and the power supply. A step-up transformer has a secondary winding inserted in series in the current conduction path from the step-up transformer to the high-pressure discharge lamp; a bypass capacitor applied between both ends thereof, and current control means for gradually increasing the rising slope of the charging voltage of the charging circuit by increasing the output current of the DC-DC converter as time passes after the power is turned on; The above D
Igniter for high pressure discharge lamp installed in C-DC converter. (2) An igniter for a high-pressure discharge lamp that applies a high-voltage pulse for starting a high-pressure discharge lamp connected to a power source via an inductive ballast, comprising a DC-DC converter and an output current of the DC-DC converter. A charging circuit that is charged with a charging circuit, a two-terminal discharge gap to which a charging voltage of the charging circuit is applied, and a primary winding inserted in series in a current-carrying path from the charging circuit to the two-terminal discharge gap, and the power supply. A step-up transformer has a secondary winding inserted in series in the current conduction path from the step-up transformer to the high-pressure discharge lamp; a bypass capacitor applied between both terminals of the high-pressure discharge lamp, the output current of the DC-DC converter is reduced at the time of initial starting of the high-pressure discharge lamp, thereby reducing the rising slope of the charging voltage of the charging circuit, and An igniter for a high-pressure discharge lamp, wherein the DC-DC converter is provided with current control means for increasing the rising slope of the charging voltage of the charging circuit by increasing the output current of the DC-DC converter at the time of restart.