JP3131257B2 - High pressure discharge lamp lighting device - Google Patents

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 FIG. 4 shows a high pressure discharge lamp lighting device of this kind. This high-pressure discharge lamp lighting device includes an igniter 2 for starting the high-pressure discharge lamp La and an inverter 1 for maintaining lighting of the high-pressure discharge lamp La. The igniter 2 applies a high voltage to start the high-pressure discharge lamp La. The high frequency power is supplied from the inverter 1 to the high pressure discharge lamp La so as to maintain the lighting.

In the above high pressure discharge lamp lighting device, an inverter
Use a so-called half bridge type as 1
You. Specifically, a DC power supply (rectified and smoothed AC power supply)
E includes two switching elements Q₁,
Q_TwoAre connected in series, and the switching element Q_TwoStraight on both ends of
Flow cut capacitor C₁Current limiting choke L₁
And capacitor C_TwoAnd a series resonant circuit consisting of
And the high-pressure discharge lamp La has a capacitor C_TwoConnected in parallel to
It is. Note that each switching element Q₁, Q _TwoTo
Diode D in anti-parallel₁, D_TwoIs connected.

When a power switch (not shown) is turned on, the inverter 1 is supplied with DC power E. At this time, the switching elements Q ₁ and Q ₂ are alternately turned on as shown in FIGS. 5 (a) and 5 (b). , Control to turn off is started. Now
When switching element Q ₁ is on, switching element Q ₂
Is off, the DC power source E, the switching element Q ₁ , the DC cut capacitor C ₁ , the current limiting choke L ₁ , and the capacitor C ₂ (the secondary winding L ₁₂ of the pulse transformer PT described later, the high pressure discharge lamp La ) current flows through a path through the capacitor C ₁ is charged to the power supply voltage of approximately DC power supply.

[0005] Then, the switching element Q ₁ is turned off, the switching element Q ₂ is turned on, the power supply electric charge charged in the capacitor C ₁ in this case, the capacitor C _1, the switching element Q _2, the capacitor C
₂ (High pressure discharge lamp La, secondary winding L of pulse transformer PT
_12), a current flows through a path of the current limiting choke L _1. Less than,
The above operation is repeated in accordance with the on / off of the switching elements Q ₁ and Q ₂ , and the high-pressure discharge lamp La has a current-limiting choke L ₁
5 by the action of the series resonant circuit comprising a capacitor C ₂ and
A sinusoidal high-frequency lamp current I _La shown in FIG.

Incidentally, the high-pressure discharge lamp La has a unique property of causing an acoustic resonance phenomenon. Therefore, the oscillation frequency of the inverter 1 is usually set to a frequency at which such an acoustic resonance phenomenon does not occur (for example, 20 to several tens kHz). However, in the above case, the selectable frequency range is narrow, and the selectable frequency is slightly higher than the oscillation frequency that causes an acoustic resonance phenomenon. In some cases, a resonance phenomenon occurs. In this case, there is a problem that the high-pressure discharge lamp La flickers or, in the worst case, the high-pressure discharge lamp La is damaged.

Therefore, as a method for preventing the above-mentioned problem from occurring, the oscillation frequency of the inverter 1 is made higher than that in the above-mentioned case (for example, 100 to several hundreds of kHz).
z) is conceivable. In this way, there is an advantage that there is no possibility of causing an acoustic resonance phenomenon due to a variation in the oscillating frequency of the inverter 1 and that the selectable frequency range is widened. Furthermore, increasing the oscillation frequency of the inverter 1, as described above, a constant current limiting choke L ₁ and capacitor C ₂ to form a series resonant circuit can be reduced, there is an advantage that Therefore device size and weight can be reduced.

When the switching elements Q ₁ and Q ₂ are turned off, a current flows in the same direction as the on period of the switching elements Q ₁ and Q ₂ due to the energy accumulated in the current limiting choke L ₁ . When the switching element Q ₁ is off, the current limiting choke L ₁ , the capacitor C ₁ , the diode D ₁ , the DC power supply E, and the capacitor C ₂ (high-pressure discharge lamp L
a, pulse transformer PT 2 winding L ₁₂₎ path in Figure 5 (the switching element to Q ₁ ON period identical direction as shown in c) electric current through the shed, and also off the switching element Q ₂ At the time, the current limiting choke L ₁ , the capacitor C ₂ (the secondary winding L ₁₂ of the pulse transformer PT, the high-pressure discharge lamp La), the diode D ₂ and the capacitor C ₁ are shown in FIG.
Current of the switching element Q ₂ in the ON period and the same direction flows as shown in (d).

In the high-pressure discharge lamp La, several tens of
In some cases, the igniter 2 is provided in a high-pressure discharge lamp lighting device in which the igniter 2 does not start unless a high voltage of 00 V is applied to both ends of the high-pressure discharge lamp La. This igniter 2
Now, a booster circuit 2a for boosting the output voltage of the inverter 1
And the high voltage obtained by the booster circuit 2a
A method of applying a voltage to both ends of the high-pressure discharge lamp La via T is generally adopted.

FIG. 6 shows a specific example of the igniter 2. In the igniter. 2 are constituted by multiple precision voltage circuit comprising a capacitor C ₃ -C ₆ and the diode D ₃ to D ₆ as a step-up circuit 2a (4 times voltage circuit in the case of FIG. 6), the multiple precision voltage a series circuit of the primary winding L ₁₁ of the pulse transformer PT and the switching element SW ₁ between the output of the circuit 2a and the negative electrode side of the DC power source E, the pulse transformer PT
The secondary winding L ₁₂ of the high pressure discharge lamp La connected in series, that is, is connected a series circuit of the secondary winding L ₁₂ and the high pressure discharge lamp La in parallel with the capacitor C _2.

If the high-pressure discharge lamp La does not light up, the impedance of the high-pressure discharge lamp La is almost infinite in this case, so that the inverter 1 operates in a no-load state. At this time, the output of the inverter 1 (A-
7A, a sinusoidal voltage having a peak value of E is generated. Now, when the potential at the point B is higher than the potential at the point A, a current flows through the point B, the diode D ₃ , the capacitor C ₃ , and the point A. At this time, the capacitor C ₃ is charged to a voltage equal to the voltage of the DC power supply E. Is done.

When the potential at the point A becomes higher than the potential at the point B, a current flows through the point A, the capacitor C ₃ , the diode D ₄ , the capacitor C ₄ and the point B, and at the same time, the capacitor C
A current using the charge ₃ as a power supply flows through the diode D ₄ and the capacitor C ₄ . Therefore, the capacitor C ₄ is charged to a voltage obtained by adding the voltage of the capacitor C _{3 to} the voltage of the DC power source E, that is, a voltage twice as high as the DC power source E.

Thereafter, in substantially the same manner, in the next half cycle, point B, capacitor C ₄ , diode D ₅ , capacitor C
_5. Capacitor C ₃ , due to the current flowing in the path of point A,
Capacitor C ₅ is charged up to twice the voltage of the DC power source E, further in the next half cycle, the capacitor C _3, the capacitor C _5, a diode D _6, the capacitor C _6, a path of the capacitor C _4, B point, the capacitor C ₆ is charged up to twice the voltage of the DC power supply E. That is, the output of the quadruple voltage circuit 2a (potential at point C with reference to point B in the figure)
Means that a voltage four times the voltage of the DC power supply E can be obtained. It is needless to say that a higher DC voltage can be obtained by connecting capacitors and diodes in multiple stages.

By repeating the above operation, the potential V _{CB at the} point C rises as shown in FIG. When the output of the multiple precision voltage circuit 2a reaches a predetermined voltage, when to turn on the switch elements SW _1, a capacitor C ₄ via a primary winding L ₁₁ of the pulse transformer PT, C ₆
Is rapidly discharged, and the pulse transformer P
The secondary winding L ₁₂ of the T high voltage pulse Vp is generated in accordance with the turns ratio of the primary winding L ₁₁ and secondary winding L ₁₂ shown in FIG. 7 (c). The high-voltage pulse Vp is applied to the high-pressure discharge lamp La via the capacitor C _2, which the high-pressure discharge lamp La is started by.

If the high-pressure discharge lamp La is not started by the application of the one high-voltage pulse Vp, the above operation is repeated as shown in FIG. In FIG. 7, the application points of the high voltage pulse Vp are indicated by T ₁ and T ₂ . Here, in such a pulse starting type high-pressure discharge lamp lighting device, in order to normally start the high-pressure discharge lamp La reliably, the peak value of the high-voltage pulse Vp is several thousand V or more, and the pulse width is several μsec or more. Desirably.

The peak value of the high-voltage pal Vp rises in proportion to the charge charged in the capacitors C ₄ and C ₆ and the turns ratio of the pulse transformer PT, and the pulse width is
_4, the primary winding of the capacitance of C ₆ and the pulse transformer PT L ₁₁
Becomes wider in proportion to the inductance value of.

[0017]

By the way, in order to reliably prevent the acoustic resonance phenomenon as described above, if the oscillation frequency of the inverter 1 is set to a high frequency of 100 kHz or more, the current-limiting choke L ₁ is several tens μH. degree, the capacitor C ₂ becomes smaller as several nF. In the case of increasing the oscillation frequency of the inverter 1 as described above, when a large inductance value of the secondary winding L ₁₂ of the pulse transformer PT, impedance of the secondary winding L ₁₂ is increased, Therefore appropriate lamp current Cannot flow through the high-pressure discharge lamp La. Therefore, the inductance value of the secondary winding L ₁₂ of the pulse transformer PT has to be low. Then, in order to thus reduce the inductance of the secondary winding L _12, it is necessary to lower inductance value of the primary winding L ₁₁ accordingly. Also, the multiple voltage circuit 2
capacitance of the capacitor C ₃ -C ₆ of a well in order to perform the normal boosting operation at the high frequency output can not be increased much capacity. Therefore, when the oscillation frequency of the inverter 1 is increased, it is difficult to secure the high-voltage pulse Vp having a desired peak value and pulse width by the igniter 2, which has a disadvantage that the starting performance is poor.

The present invention has been made in view of the above points, and an object of the present invention is to provide a high pressure discharge lamp lighting device capable of sufficiently securing the starting performance of a high pressure discharge lamp. is there.

[0019]

According to the present invention, a DC power supply, an inverter for converting power supplied from the DC power supply into AC power, and an AC power supplied from the inverter are provided to achieve the above object. And a igniter that starts by applying a high-voltage pulse to the high-pressure discharge lamp. The output stage of the inverter includes a DC cut capacitor and an LC series resonance circuit. And a booster circuit for feeding back the boosted output to the output of the inverter. A secondary winding is connected in series to the high-pressure discharge lamp, and the primary winding is connected in parallel with the output of the inverter via a switch element. The igniter includes a connected pulse transformer.

[0020]

The present invention has the above-described structure,
The DC cut capacitor and the capacitor of the LC series resonance circuit are charged up to the voltage obtained by superimposing the output of the booster circuit on the output of the inverter, and a high-voltage pulse is generated by using the charged charges of these capacitors. A high-pressure pulse having a sufficiently wide pulse width can be obtained, and the starting performance of the high-pressure discharge lamp can be sufficiently ensured.

[0021]

1 to 3 show an embodiment of the present invention. The basic configuration of the present embodiment is the same as that of the above-described conventional circuit of FIG.
the output of a through the diode D ₇ is connected to the output terminal A of the inverter 1, the primary winding L of a pulsed transformer PT
₁₁ and a switch element SW ₁ in series with a capacitor C ₂
Is characterized in that they are connected in parallel.

The operation of this embodiment will be described below. Before starting the high-pressure discharge lamp La, the inverter 1 operates in the no-load state as described above, and a sine-wave voltage shown in FIG. 7A is generated at the output (between AB). Further, the booster circuit 2 of the present embodiment also has the same configuration as that of FIG. 6, and generates a high DC voltage using the output of the inverter 1 as a power supply. However, since in the case of this embodiment are through the diode D ₇ of the output of the booster circuit 2 is connected to the output terminal of the inverter 1 (A end in the drawing), the output of the booster circuit 2 is a diode D ₇ To the power supply side (the output of the inverter 1) through the capacitor C ₁ and C ₂ , so that the output voltage of the inverter 1 is applied to the capacitors C ₁ and C ₂ by the booster circuit 2 shown in FIG.
The battery is charged up to the voltage on which the output voltage a is superimposed.

When the voltage between both ends of the capacitors C ₁ and C ₂ reaches a predetermined voltage, the switch element SW ₁ is turned on to transfer the electric charges charged in the capacitors C ₁ and C ₂ to the pulse transformer PT. is discharged through the primary winding L _11, this time the high-pressure pulse Vp is generated in the secondary winding L ₁₂ of the pulse transformer PT, a high voltage pulse V to the high-pressure discharge lamp La
p is applied. At this time, the applied voltage of the high-pressure discharge lamp La (voltage applied between B and D in FIG. 1) is shown in FIG.

That is, in the case of this embodiment, the booster circuit 2a
Is superimposed on the output of the inverter 1 and the high-voltage pulse Vp is superimposed on the superimposed voltage, so that the peak value of the high-voltage pulse Vp applied to the high-pressure discharge lamp La can be increased. Furthermore, since the superimposed output of the booster circuit 2a to the output of the inverter 1, the inductance value of the secondary winding L ₁₂ of the pulse transformer PT supplies an appropriate lamp current even when a large high-pressure discharge lamp La Can be. Further, as a capacitor for generating a high voltage pulse in the pulse transformer PT in this embodiment, since the are using the capacitor C ₁ and capacitor C ₂ for DC cut, that the pulse width of the voltage pulse Vp is also sufficiently wide it can. That is, the capacitances of the capacitors C ₁ and C ₂ can be set to be two or three orders of magnitude larger than the capacitances of the capacitors C ₄ and C ₆ of the multiple voltage circuit shown in FIG. FIG. 3A shows a high-voltage pulse obtained in this embodiment, and FIG. 3B shows a high-voltage pulse obtained in a conventional circuit. As described above, in the present embodiment, the high-pressure pulse Vp having a sufficient peak value and pulse width can be obtained, so that the high-pressure discharge lamp La
Can be started stably.

By the way, as in this embodiment, the capacitor C
_When the high-voltage pulse Vp is generated using the charged charges of ₁ and C _2, the voltage applied to the high-pressure discharge lamp La has a substantially sawtooth waveform as shown in FIG. Effective voltage can be suppressed low, and therefore, even if the high-pressure discharge lamp La cannot be started at the end of life or the like, safety can be ensured.

Although the above description has been given of the case where a half-bridge type inverter is used, it goes without saying that the present invention can be applied to, for example, a full-bridge type inverter.

[0027]

As described above, the present invention provides a DC power supply, an inverter for converting power supplied from the DC power supply to AC power, a high-pressure discharge lamp for lighting with AC power supplied from the inverter, An igniter that starts by applying a high-voltage pulse to the high-pressure discharge lamp, includes a DC cut capacitor and an LC series resonance circuit at the output stage of the inverter, boosts the output voltage of the inverter, and outputs the boosted output to the inverter. And a pulse transformer having a secondary winding connected in series to the high-pressure discharge lamp and a primary winding connected in parallel to the output of the inverter via a switch element. The igniter has a DC cut capacitor and an LC series resonant circuit capacitor up to the voltage obtained by superimposing the output of the booster circuit on the output of the inverter. The high-voltage pulse can be generated by using the charge of these capacitors, and a high-voltage pulse having a sufficiently high peak value and a sufficiently wide pulse width can be obtained, and the starting performance of the high-pressure discharge lamp can be sufficiently improved. Can be secured.

[Brief description of the drawings]

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

FIG. 2 is a diagram showing a voltage waveform applied to the high pressure discharge lamp of the above.

FIGS. 3A and 3B are explanatory diagrams showing a waveform of a high-voltage pulse obtained in the above and a waveform of a high-voltage pulse obtained in a conventional circuit.

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

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

FIG. 6 is a circuit diagram specifically showing the booster circuit of the above.

FIG. 7 is a voltage waveform diagram of each part of the above.

[Explanation of symbols]

First inverter 2 igniter 2a booster circuit La high-pressure discharge lamp C _1, C ₂ capacitors L ₁ current limiting choke PT pulse transformer L ₁₁ 1 winding L ₁₂ 2 winding SW ₁ switch elements E DC power supply

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H05B 41/24-41/298 H05B 41/18

Claims (1)

(57) [Claims] A DC power supply; an inverter for converting power supplied from the DC power supply to AC power; a high-pressure discharge lamp for lighting with the AC power supplied from the inverter;
An igniter that starts by applying a high-voltage pulse to the high-pressure discharge lamp, includes a DC cut capacitor and an LC series resonance circuit at the output stage of the inverter, boosts the output voltage of the inverter, and outputs the boosted output to the inverter. And a pulse transformer having a secondary winding connected in series to the high-pressure discharge lamp and a primary winding connected in parallel to the output of the inverter via a switch element. A high pressure discharge lamp lighting device comprising an igniter.