JPH05166592A - Lighting device for high pressure electric discharge lamp - Google Patents

Abstract

PURPOSE:To supply a proper lamp current to a high pressure electric discharge lamp without enlarging the component parts of an ignitor and increasing the cost of the lamp even if the oscillation frequency of an inverter is increased. CONSTITUTION:An inverter 1 converts DC power supplied from a DC power source E into AC power and supplies it to a high pressure electric discharge lamp Lp. The high pressure electric discharge lamp Lp is started by application of a high-pressure pulse using an ignitor 2. The ignitor 2 is provided with a pulse transformer PT whose secondary coil L2 is connected in series with the high pressure electric discharge lamp Lp. A capacitor C5 is connected in series with the secondary coil L2 of the pulse transformer PT. The resonance frequency of a series resonance circuit comprising the secondary coil L2 and the capacitor C5 is made to almost coincide with the oscillation frequency of the inverter 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high pressure discharge lamp lighting device for lighting a high pressure discharge lamp such as a metal halide lamp or a mercury lamp.

[0002]

2. Description of the Related Art A high pressure discharge lamp lighting device of this type is shown in FIG. This high-pressure discharge lamp lighting device comprises an igniter 2 for starting the high-pressure discharge lamp Lp and an inverter 1 for maintaining lighting of the high-pressure discharge lamp Lp. A high voltage is applied by the igniter 2 to start the high-pressure discharge lamp Lp. The inverter 1 supplies high-frequency electric power to the high-pressure discharge lamp Lp to maintain lighting.

In the above high pressure discharge lamp lighting device, a so-called separately excited half bridge type is used as the inverter 1. Specifically, two switching elements S ₁ and S ₂ are connected in series to a DC power source (including one that is formed by rectifying and smoothing an AC power source) E, and a DC cutting capacitor is provided at both ends of the switching element S _2. A series resonance circuit consisting of a current limiting choke L ₁ and a capacitor C ₂ is connected via C ₁ , and the high pressure discharge lamp Lp is connected in parallel to the capacitor C ₂ . In addition, the respective switching elements S ₁ , S
The ₂ is connected diodes D _1, D ₂ antiparallel s husband. Then, the respective switching elements S ₁ and S ₂ are alternately turned on and off by the control circuit X ₁ .

When the power switch (not shown) is turned on, the inverter 1 is supplied with the DC power E, and at this time, the control circuit X ₁ causes the switching elements S ₁ and S ₂ to operate.
As shown in (a) and (b), control for alternately turning on and off is started. Now, assuming that the switching element S ₁ is on and the switching element S ₂ is off, the DC power source E, the switching element S ₁ , the DC cutting capacitor C ₁ , the current limiting choke L ₁ , the capacitor C ₂ (pulses described later) Secondary winding L _{2 of} transformer PT, high pressure discharge lamp Lp)
A current flows through the path through the capacitor C ₁ and the capacitor C ₁ is almost charged to the power supply voltage of the DC power supply.

Then, when the switching element S ₁ is turned off and the switching element S ₂ is turned on, at this time, the electric charge charged in the capacitor C ₁ is used as a power source, and the capacitor C ₁ , the switching element S ₂ and the capacitor C _{2 are used} .
₂ (High-pressure discharge lamp Lp, secondary winding L of pulse transformer PT
₂ ), current flows through the path of the current limiting choke L ₁ . Less than,
The above operation is repeated depending on whether the switching elements S ₁ and S ₂ are on or off, and the high-pressure discharge lamp Lp has a current limiting choke L ₁
The operation of the series resonant circuit consisting of the capacitor and the capacitor C ₂ is shown in FIG.
The sinusoidal high frequency power shown in (e) is supplied.

By the way, the switching element S₁, S
₂When off, the current limiting choke L ₁Energy accumulated in
Switching element S by Rugi₁, S₂Same as on period of
Electric current is passed in one direction. Switching element S₁Is o
At the time of F, current limiting choke L₁, Capacitor C₁, Da
Iodo D₁, DC power supply E, capacitor C₂(High voltage discharge
Secondary winding L of lamp Lp and pulse transformer PT₂) Through
Switching element S along the path₁In the same direction as the on period of
A current is applied and the switching element S₂At the off time
Is a current limiting choke L₁, Capacitor C₂(Pulse Tran
Secondary winding L of PT₂, High-pressure discharge lamp Lp), diode
D₂, Capacitor C₁Switching element S along the path₂of
A current flows in the same direction as the ON period. Die at this time
Aether D ₁, D₂The current flowing in is shown in Fig. 5 (c) and (d).
Shown with diagonal lines.

The igniter 2 is composed of a pulse generating circuit 2a for generating a pulse and a pulse transformer PT for boosting the output of the pulse generating circuit 2a. The secondary winding L ₂ of the pulse transformer PT has a high voltage discharge. It is inserted in series with the lamp Lp, and the series circuit of the discharge lamp La and the secondary winding L ₂ is connected to both ends of the capacitor C ₂ . FIG. 6 is a diagram specifically showing an example of the pulse generation circuit 2a of the igniter 2 and a bidirectional switching element S ₄ such as a triac inserted in series in the primary winding L ₃ of the pulse transformer PT. , a trigger element S ₃ to trigger the switching element S _4, and the trigger circuit composed of the resistor R ₂ and capacitor C ₄ to breakover the trigger element S _3, 1 winding L ₃ and the switching elements of the pulse transformer PT And a charging circuit composed of a resistor R ₁ for supplying a DC voltage and a capacitor C _{3 in} a series circuit with S ₄ ,
An alternating current power supply AC is connected to the switch S in the pulse generating circuit 2a.
It is supplied via W. Here, the switch SW
Supplies the AC power supply AC to the pulse generation circuit 2a only when the high pressure discharge lamp Lp is started.

Now, when the switch SW is turned on, the capacitor C ₃ is charged via the resistor R ₁ and the capacitor C ₄ is charged via the primary winding L ₃ of the pulse transformer PT and the resistor R _2. It When the voltage across the capacitor C ₄ reaches the breakover voltage of the trigger element S _3, and discharged through the trigger element S ₃ to charge the capacitor C _4, thereby gate current to the switching element S ₄ To conduct. When the switching element S ₄ is turned on in this way, the electric charge charged in the capacitor C ₃ is discharged through the primary winding L ₃ and the switching element S _4, and the secondary winding L ₂ of the pulse transformer PT is discharged. Is 1
A high-voltage pulse (for example, 4) according to the turn ratio with the next winding L _3.
000V) is generated. This high-voltage pulse is applied to both ends of the high-pressure discharge lamp Lp via the capacitor C ₂ . Here, the high-voltage pulse is applied to the high-pressure discharge lamp Lp so as to be superimposed on the output of the inverter 1. Then, the high pressure pulse starts the high pressure discharge lamp Lp.

When the high pressure discharge lamp Lp is started in this way, the switch SW is turned off thereafter,
The high-pressure pulse is no longer applied to the high-pressure discharge lamp Lp from the igniter 2, and the high-pressure discharge lamp Lp is stably turned on by the output of the inverter 1.

[0010]

The high-pressure discharge lamp Lp has a peculiar property of causing an acoustic resonance phenomenon. Therefore, the oscillation frequency of the inverter 1 is usually set to a frequency (for example, 20 to several tens of kHz) at which such an acoustic resonance phenomenon does not occur. However, in the above case, the selectable frequency range is narrow, and the selectable frequency is a frequency slightly higher than the oscillation frequency that causes the acoustic resonance phenomenon. A resonance phenomenon may occur, and in this case, the high-pressure discharge lamp Lp may flicker,
Alternatively, in the worst case, the high pressure discharge lamp Lp may be damaged.

Therefore, as a method for avoiding the above problems, the oscillation frequency of the inverter 1 is set higher than that in the above case (for example, 100 to several hundreds of kHz).
z) is possible. By doing so, there is an advantage that the acoustic resonance phenomenon does not occur due to the variation of the oscillation frequency of the inverter 1, and the selectable frequency range is widened. Further, as described above, if the oscillation frequency of the inverter 1 is increased, the constants of the current limiting choke L ₁ and the capacitor C ₂ that form the series resonance circuit can be reduced, and the size and weight of the device can be reduced. For example, the oscillation frequency of the inverter 1 is 100 to several hundreds of kHz as described above.
If z is selected, the current limiting choke L ₁ can be set to several tens μH and the capacitor C ₂ can be set to several nF.

However, when the oscillation frequency of the inverter 1 is increased as described above, the inductance value of the secondary winding L ₂ of the pulse transformer PT of the igniter 2 needs to be set to several tens μH or less. This is the secondary winding L ₂ of the pulse transformer PT when the oscillation frequency of the inverter 1 is increased.
If the inductance value is large, the impedance of the secondary winding L ₂ becomes large, so that an appropriate lamp current cannot flow through the high pressure discharge lamp Lp. However, it is difficult to reduce the inductance value of the secondary winding L ₂ of the pulse transformer PT in this way for the following reason.

That is, in order to stably start the high pressure discharge lamp Lp, the output of the igniter 2 has a peak value of several thousand volts.
It is necessary to be a high-voltage pulse with a pulse width of several μsec or more. Here, the pulse width of the high-voltage pulse is determined by the capacitance of the capacitor C ₃ and the pulse transformer PT in FIG.
It is substantially determined by the inductance value of the primary winding L ₃ for, in order to the pulse width is larger one of the inductance value of the primary winding L ₃ for capacitance and the pulse transformer PT of the capacitor C ₃ Must.

Now, assuming that the inductance value of the primary winding L ₃ is increased, the peak value is several 1000V.
In order to obtain a high-voltage pulse of the order of magnitude, it is necessary to increase the inductance value of the secondary winding L ₂ , and in this case, there is a problem that an appropriate lamp current cannot be secured as described above. Therefore, it is conceivable to increase the capacity of the capacitor C ₃ . However, in this case, the size of the capacitor C ₃ becomes large and the current flowing when the switching element S ₄ is turned on increases, so that the switching element S ₄ having a large withstanding capability is required.

As another method, a pulse transformer PT
A method of reducing the step-up ratio of is also possible. However, in this case, it is necessary to apply a high voltage to the primary winding L ₃ of the pulse transformer PT, that is, it is necessary to increase the voltage of the power source of the pulse generating circuit 2a, and as a result, the capacitor C ₃ and Since it is necessary to increase the withstand voltage of the switching element S ₄ , there is a problem that the size of the component and the cost are increased.

The present invention has been made in view of the above points, and it is an object of the present invention to supply an appropriate lamp current to a high pressure discharge lamp even when the oscillation frequency of an inverter is increased, and An object of the present invention is to provide a high pressure discharge lamp lighting device that does not increase the size and cost of the components of the igniter.

[0017]

In order to achieve the above object, the present invention provides a DC power supply, an inverter for converting DC power supplied from the DC power supply into AC power, and an AC power supplied from the inverter. It consists of a high-pressure discharge lamp that lights up with electric power and an igniter that applies a high-voltage pulse to start the high-pressure discharge lamp. The igniter includes a pulse transformer in which a secondary winding is connected in series with the high-pressure discharge lamp. A capacitor is connected in series with the secondary winding of the transformer, and the resonance frequency of the series resonance circuit composed of the secondary winding and the capacitor is made to substantially match the oscillation frequency of the inverter.

[0018]

According to the present invention, as described above, a capacitor is inserted in series with the secondary winding of the pulse transformer connected in series to the high pressure discharge lamp of the igniter, and the series is constituted by the secondary winding and the capacitor. By making the resonance frequency of the resonance circuit substantially equal to the oscillation frequency of the inverter, the series circuit of the high pressure discharge lamp, the secondary winding of the pulse transformer, and the capacitor can be used when the high pressure discharge lamp is lit by the output of the inverter. The impedance can be made almost only the resistance component of the high-pressure discharge lamp by the resonance phenomenon of the series resonance circuit composed of the secondary winding and the capacitor, which increases the inductance of the secondary winding of the pulse transformer. Even so, an appropriate lamp current can be supplied to the high-pressure discharge lamp, and the oscillation frequency of the inverter is increased to prevent lighting acoustic resonance. If, even changing anything like the igniter side so as not to unnecessary, in which so as not to cause increase in size and cost of the igniter components.

[0019]

FIG. 1 shows an embodiment of the present invention. The basic configuration of this embodiment is the same as that of the conventional circuit of FIG. 4 described above. In the case of this embodiment, a capacitor C ₅ is connected in series with the high pressure discharge lamp Lp as shown in the figure. That is, the secondary winding L ₂ of the pulse transformer PT, the high-pressure discharge lamp Lp, and the capacitor C ₂ at both ends of the capacitor C _2.
The feature is that ₅ series circuits are connected. And
The inductance value and the capacitance are set so that the secondary winding L ₂ and the capacitor C ₅ form a series resonance circuit having the oscillation frequency of the inverter 1 as the resonance frequency.

With this configuration, the impedance of the series circuit of the secondary winding L ₂ of the pulse transformer PT, the high-pressure discharge lamp Lp, and the capacitor C ₅ viewed from the inverter 1 side can be adjusted to the secondary winding L ₂ and the capacitor. Due to the resonance phenomenon of the series resonance circuit composed of C ₅ , only the resistance value of the high pressure discharge lamp Lp can be obtained. Here, assuming that the inductance value of the secondary winding L ₂ is large, in this case, the capacitor C ₅ is adjusted so that the resonance frequency becomes the oscillation frequency of the inverter 1.
The capacity of can be reduced. Therefore, even if the oscillation frequency of the inverter 1 is increased, the inductance value of the secondary winding L ₂ can be increased. Therefore, the inductance value of the primary winding L ₃ of the pulse transformer PT can be increased, and it is necessary to stably start the high-pressure discharge lamp Lp without increasing the capacity of the capacitor C ₃ and increasing the power supply voltage. It is possible to secure a high-voltage pulse having an appropriate peak value and pulse width. Therefore, even if the oscillation frequency is raised so as not to cause the acoustic resonance phenomenon of the inverter 1, the high pressure discharge lamp Lp can be stably started by the igniter 2, and the size and cost of the parts are not increased.

(Embodiment 2) FIGS. 2 and 3 show another embodiment of the present invention.
An example is shown. In this embodiment, as shown in FIG.
Mainly developed for high-pressure discharge lamp lighting device using J-type inverter 1.
It is an application of Ming. This high pressure discharge lamp lighting device
The inverter 1 has switching elements at both ends of the DC power source E.
S₁₁, S₁₃Series circuit consisting of and switching elements
S₁₂, S₁₄Switching with a series circuit consisting of
Element S₁₁, S₁₃Connection point and switching element S ₁₂, S₁₄
Current limit choke L between the connection point₁And capacitor C₂
Connect a series resonance circuit consisting of₂Parallel to
Secondary winding L of pulse transformer PT of igniter 2₂,
High-pressure discharge lamp Lp and capacitor C according to the present invention_FiveAnd
It is connected. In addition, each switching element S₁₁~ S₁₄To
Is a current limiting choke L when turned off₁The energy stored in
Diode D for emitting₁₁~ D₁₄Connected in anti-parallel
There is.

In this full bridge type inverter 1,
The switching element S ₁₁ , S ₁₄ and the switching element S ₁₂ , S ₁₃ are respectively set, and a control circuit not shown in FIG.
As shown in (a) and (b), the switching element S ₁₁
On alternately to S ₁₄ for each set, it is constituted such that it is turned off. Now, assuming that the switching elements S ₁₁ and S ₁₄ are on and the switching elements S ₁₂ and S ₁₃ are off, the DC power source E,
Current flows through the path of the switching element S ₁₁ , the current limiting choke L ₁ , the capacitor C ₂ (secondary winding L ₂ of the pulse transformer PT, the high-pressure discharge lamp Lp, the capacitor C ₅ ) and the switching element S ₁₄ , and switching is performed in reverse. When the elements S ₁₂ and S ₁₃ are turned on and the switching elements S ₁₁ and S ₁₄ are turned off, the DC power source E, the switching element S ₁₂ , the capacitor C ₂ (the capacitor C ₅ , the high pressure discharge lamp Lp, and the pulse transformer PT 2).
Next winding L ₂ ), current limiting choke L ₁ , switching element S
_{In the 13} routes, the current in the opposite direction to the above case is applied to the high pressure discharge lamp Lp.
Is supplied to. In the inverter 1 of this type, all the switching elements S _{11 to} S ₁₄ are off during the period in which the switching elements S ₁₁ and S ₁₄ and the switching elements S ₁₂ and S ₁₃ are alternately turned on and off. The dead-off period is set so that the power supply short circuit does not occur. Further, the broken line portions in FIGS. 3C and 3D show the current flowing when the charge accumulated in the current limiting choke L ₁ is discharged via the diodes D _{11 to} D ₁₄ .

Even when the full bridge type inverter 1 is used, the sinusoidal current shown in FIG. 3 (e) is passed through the high pressure discharge lamp Lp. The igniter 2 has the same structure as that shown in FIG. Even if the inverter 1 is a half-bridge type as in the present embodiment, the components of the igniter 2 are increased in size and cost even when the oscillation frequency of the inverter 1 is increased as in the case of the first embodiment. An appropriate lamp current can be supplied to the high-pressure discharge lamp Lp without inviting an increase.

[0024]

As described above, the present invention provides a DC power supply, an inverter for converting DC power supplied from this DC power supply to AC power, and a high-pressure discharge lamp that is lit by the AC power supplied from this inverter. , An igniter for starting a high-pressure discharge lamp by applying a high-voltage pulse, the igniter having a pulse transformer in which a secondary winding is connected in series with the high-pressure discharge lamp, and in series with a secondary winding of the pulse transformer. When a high pressure discharge lamp is lit by the output of the inverter, the capacitor is connected to the In addition, the impedance of the series circuit consisting of the high voltage discharge lamp, the secondary winding of the pulse transformer and the capacitor, Due to the vibration phenomenon, almost only the resistance component of the high-pressure discharge lamp can be made, so that even if the inductance of the secondary winding of the pulse transformer is increased, an appropriate lamp current can be supplied to the high-pressure discharge lamp, and therefore the lighting acoustic resonance Even if the oscillating frequency of the inverter is increased to prevent the phenomenon, any change on the igniter side is not necessary, and the components of the igniter are not upsized and the cost is not increased.

[Brief description of drawings]

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

FIG. 2 is a circuit diagram of another embodiment.

FIG. 3 is an operation explanatory diagram of the above.

FIG. 4 is a circuit diagram of a conventional example.

FIG. 5 is an operation explanatory diagram of the above.

FIG. 6 is a specific circuit diagram of the above igniter.

[Explanation of symbols]

First inverter 2 igniter Lp pressure discharge lamp C ₅ condenser PT pulse transformer L ₂ 2 winding E DC power supply

Claims (1)

[Claims] 1. A DC power supply, an inverter for converting DC power supplied from the DC power supply into AC power, a high-pressure discharge lamp lit with the AC power supplied from the inverter, and a high voltage by applying a high-voltage pulse. An igniter for starting a discharge lamp, the igniter includes a pulse transformer in which a secondary winding is connected in series with a high pressure discharge lamp, and a capacitor is connected in series with the secondary winding of the pulse transformer,
A high pressure discharge lamp lighting device, characterized in that a resonance frequency of a series resonance circuit composed of the secondary winding and a capacitor is substantially matched with an oscillation frequency of an inverter.