JP3210690B2 - 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 discharge lamp lighting apparatus for converting a voltage of a DC power supply into a rectangular wave voltage by an inverter, superimposing a high-voltage pulse on the rectangular wave voltage by an igniter, and applying the pulse to a high-pressure discharge lamp. It is.

[0002]

2. Description of the Related Art A general structure of a discharge lamp lighting device for lighting a high pressure discharge lamp is shown in FIG. In this discharge lamp lighting device,
A square wave voltage is generated using a ballast A including a half-bridge configuration or a full-bridge configuration inverter,
This rectangular wave voltage is applied to the high-pressure discharge lamp La, and a high-voltage pulse is generated by the igniter 2 which operates using the output of the ballast A as a power supply. ₁ is applied to the high-pressure discharge lamp La. Then, the high-pressure discharge lamp La is started by the high-voltage pulse applied from the igniter 2, and the lighting of the high-pressure discharge lamp La is maintained by the rectangular wave voltage by the ballast A. The ballast A has a rectifying circuit or a rectifying and smoothing circuit for rectifying the AC power supply e.

[0003] By the way, in the above discharge lamp lighting device,
Reason for the inverter are used as for generating a square wave output, the inverter is to generate a sine wave output, if there are variations in the time point of generation of high-voltage pulse by variations in the on-time switch S _1, FIG. 10 (a)
As shown on the negative electrode side, the peak value of the high-voltage pulse greatly fluctuates, and accordingly, the lamp current also fluctuates greatly. Therefore, a circuit for controlling timing for generating a pulse is required.

However, in the case of an inverter that generates a rectangular wave output, the period during which the voltage is constant is long. Is not as problematic as the difference.
Therefore, in the case of a discharge lamp lighting device using this type of igniter 2, it is preferable that the inverter generates a rectangular wave output.

[0005] The ignition in this type of discharge lamp lighting device
FIG. 6 shows a specific configuration of the data 2. In this igniter 2,
For example, an inverter (rectifier or rectifier flat) as a ballast
(Including smoothing circuit) A square wave voltage of 1 to several tens Hz is applied.
And the capacitor C _TwoIs the resistance R₁Charge via
Is done. And switches such as triacs (from outside
Switch that turns on when a trigger signal is given) S₁But
When turned on, the secondary winding n_TwoIs connected in series with the high-pressure discharge lamp La
Continued pulse transformer PT₁Primary winding n₁Through
And the capacitor C_TwoIs discharged. On this occasion
And pulse transformer PT₁Primary winding n₁Current flowing through
The secondary winding n_TwoA high-voltage pulse is induced in the
High voltage pulse voltage is bypass capacitor C₁Through high
Is applied to the high-pressure discharge lamp La, and the high-pressure discharge lamp La is started.
You.

[0006] Here, high-voltage pulse waveform shown in FIG. 7 (a) is generated in the secondary winding n ₂ of the pulse transformer PT _1. Conventionally, as shown in FIG. 7B, the peak value of the high-voltage pulse is matched by the polarity of the pulse having the maximum peak value in the high-voltage pulse and the polarity of the rectangular wave output of the inverter. Was raised. When starting the high-pressure discharge lamp La with this type of igniter 2 (that is, shifting from glow discharge to arc discharge), the following two methods are generally considered.

As a first method, there is a method in which a pulse having a narrow pulse width (for example, several tens ns) is generated in a cycle of several hundred Hz or more, and the high pressure discharge lamp La is shifted from a glow discharge to an arc discharge. As a second method, there is a method in which two to three pulses having a wide pulse width (for example, several μs) are generated and the high-pressure discharge lamp La shifts from glow discharge to arc discharge.

The difference between the two methods is that pulse 1
There is a great difference in the energy per unit, especially in the pushing current after glow discharge. Here, in the case of the first method, an element (for example, a spark gap or the like) that can switch at a high speed is required. At present, such an element is expensive and it is difficult to increase the switching accuracy. Also, for reasons such as generating noise, the second
The method described above is generally and often used.

[0009]

As shown in FIG. 9 (a), the current flowing through the high-pressure discharge lamp La is divided into two currents, namely, a current generated by a rectangular wave output from the inverter and a current generated by a high-voltage pulse from the igniter 2. There is an element, and the electric current shown in FIG. 2 (b) obtained by adding these elements flows to the high-pressure discharge lamp La.

When a high-voltage pulse is applied to the high-pressure discharge lamp La, the lamp current flowing through the high-pressure discharge lamp La is shown in FIG.
It is known to be as shown in FIG. That is, FIG.
As shown in (b), immediately after the high-pressure discharge lamp La starts arc discharge, the current flowing from the high-pressure side to the low-pressure side of the high-pressure discharge lamp La is small, and then the current flowing in the opposite direction is large. (The absolute value of peak B is larger than peak A in the figure). Incidentally, the current as described above vibrates, by LC circuit composed of the secondary winding n ₂ and the bypass capacitor C ₁ of the pulse transformer PT ₁ connected in series to the high pressure discharge lamp La.

Here, the high pressure discharge lamp L shown in FIG.
The lamp current does not flow until “a” starts discharging (period indicated by “a” in the figure). Then, when the discharge of the high-pressure discharge lamp La starts, the lamp current flows in the remaining period of the positive cycle (the period indicated by B in FIG. 8). In other words, the lamp current flows only during the period indicated by B in FIG. On the contrary,
The current flowing in the next negative cycle flows in all the periods indicated by d in FIG. Therefore, even if the high pressure discharge lamp L
Even if the discharge start time of a is earlier, the peak value of the current is higher in B than in A.

Therefore, in the conventional igniter 2 shown in FIG. 6, the peak value of the current flowing through the high-pressure discharge lamp La becomes low, and only a pushing current that is insufficient for shifting the high-pressure discharge lamp La from glow discharge to arc discharge. I can't shed. Therefore, it is conceivable to increase the peak current of the lamp current indicated by A in FIG. In this case, or to increase the capacitance of the bypass capacitor C ₁ in FIG. 6, the primary winding n of the pulse transformer PT _1
The energy may be increased by increasing the voltage applied to ₁ . However, in such a case, there is a problem that the igniter 2 becomes large. In addition, the peak value of the high-voltage pulse voltage cannot be set unnecessarily high due to, for example, the structure of the socket of the high-pressure discharge lamp La, the withstand voltage, and the withstand voltage of the high-voltage wire, and is naturally limited. The present invention has been made in view of the above points, and an object of the present invention is to provide a discharge lamp lighting device capable of appropriately increasing a pushing current.

[0013]

According to the present invention, in order to achieve the above object, an inverter for converting a voltage of a DC power supply into a rectangular wave voltage, and a high-voltage pulse superimposed on an output of the inverter to form a high-pressure discharge lamp. An igniter to be applied, and the igniter generates a high-voltage pulse such that the polarity of the pulse having the maximum peak value is opposite to the rectangular wave output of the inverter.

[0014]

The present invention has the above-described structure,
The lamp current actually flowing through the high-pressure discharge lamp is increased until the capability inherent in the igniter is effectively exhibited, thereby increasing the pushing current and smoothly starting the high-pressure discharge lamp.

[0015]

【Example】

(Embodiment 1) FIGS. 1 and 2 show an embodiment of the present invention.
In the present embodiment, as shown in FIG. 1, a half-bridge inverter is used as the inverter 1 for converting a DC voltage into a rectangular wave voltage. In the inverter 1, switches S ₂ and S ₃ and capacitors C ₃ and C ₄ are connected in series at both ends of voltage terminals a and b to which a DC voltage is applied, respectively, and a connection point of the switches S ₂ and S ₃ and A high-pressure discharge lamp La is connected between the connection points of the capacitors C ₃ and C ₄ via a current-limiting inductance element L ₁ . Note that the switch S _2, S ₃ respectively diodes D _1, D ₂ are connected in parallel, the switch S _2, S ₃ are alternately turned on and off, applying a rectangular wave voltage between c-d.

The igniter 2 has the same configuration as the conventional example described with reference to FIG. Specifically, insert the secondary winding n ₂ of the pulse transformer PT ₁ between the limiting inductance element L ₁ and the high-pressure discharge lamp La, the secondary winding n
₂ and a high-pressure discharge lamp La, a capacitor C
A series circuit of a ₂ and a resistor R _1, is connected to the primary winding n ₁ of the pulse transformer PT ₁ through the switch S ₁ across the capacitor C _2. The bypass capacitor C ₁ is coupled across the series circuit of the secondary winding n ₂ and the high-pressure discharge lamp La. However, in this embodiment, the pulse transformer P which is wound so as to have the opposite polarity in the conventional example of FIG.
The difference is that the primary windings n ₁ and n ₂ of T ₁ are wound in the same polarity.

At the time of starting, for example, the switch S_TwoIs on
Power supply terminal a → switch S_Two
→ Inductance element L₁→ Capacitor C_Two→ resistance R₁
→ Capacitor C_Four→ The path of the power supply terminal b and the capacitor C
_ThreeUsing the electric charge charged to_Three→ S
Switch S_Two→ Inductance element L₁→ Capacitor C _Two
→ resistance R₁→ Capacitor C_ThreeAnd capacitor C
_TwoThe current that charges the battery flows, and when this current is flowing
Switch S₁Is turned on, the capacitor C_TwoCharge of
Pulse transformer PT with electric charge₁Primary winding n₁Current
Flow, secondary winding n_TwoHigh with the winding start (black circle) direction positive
A pressure pulse is induced. This high pressure pulse causes condensation
Sa C₁Through the inverter 2 to the high-pressure discharge lamp La.
A voltage in a direction opposite to the shape wave output is applied. That is, FIG.
As shown in (a), the igniter 2 has the maximum peak value.
The polarity of the generated pulse is the same as the polarity of the square wave output of the inverter 1.
Reverse.

[0018] Then, the capacitor C ₁ by high voltage pulse is charged, the capacitor C ₁ → 2 winding n ₂ → the high-pressure discharge lamp L as a power source to turn charges the capacitor C ₁
a → a path of the capacitor C _1, the lamp current at the point B resulting peaks described in connection with FIG 8 flows. The direction of the lamp current at this time coincides with the direction of the lamp current flowing due to the rectangular wave output of the inverter 1. Therefore, at this time, the lamp current increases, that is, the pushing current can be increased. Therefore, the high pressure discharge lamp La
Can be promptly shifted from glow discharge to arc discharge for starting, and the startability is improved. Moreover, if the effect of increasing the pushing current in one high-voltage pulse is obtained as described above, when viewed as a plurality of high-voltage pulses,
Further, the effect of increasing the pushing current becomes remarkable.

Hereinafter, the capacitor C ₁ and the secondary winding n
_The oscillating current flows through the LC circuit according to ₂ , but since the amplitude of the oscillating current is attenuated, it hardly affects the starting of the high-pressure discharge lamp La. In the above case, the switch S ₂
Although There has been described a case where the ON, when the switch S ₃ is turned on, as shown in the partial square-wave voltage is negative in FIG. 2, only the polarity is reversed, as in the case of above The polarity of the lamp current flowing by the rectangular wave output of the inverter 1 and the maximum lamp current flowing by the igniter 2 match, and the pushing current can be increased.

Since the voltage of the high-voltage pulse at the time of the instantaneous restart is tens of kV and the rectangular wave voltage is about several percent of the high-voltage pulse, the sign of the rectangular wave voltage is so small that it can be ignored. There is no problem. To explain this point in more detail, generally, in the case of a high-pressure discharge lamp such as a metal halide lamp, the lamp voltage at the time of instantaneous restart is one hundred and several tens of volts.
V) is required. In this state, even if the peak voltage of the high-voltage pulse is 15 kV and the polarity at which the pulse having the maximum peak value of the igniter 2 appears is not opposite to the polarity of the rectangular wave output of the inverter 1, the lamp applied to the high-pressure discharge lamp Voltage is 14.7kV (15kV-300V)
In the opposite case, 15.3 kV (15 kV + 300
V), there is no significant difference in the lamp voltage applied to the high-pressure discharge lamp irrespective of the sign of the rectangular wave voltage, and the sign of the rectangular wave voltage can be ignored.

In the case of the above embodiment, the inverter 1
Has been described in the case of a half-bridge configuration.
The right part from e-e 'line in, as a series circuit of each diode D _3, D ₄ switches S ₄ which are connected in parallel, S ₅ as shown in FIG. 3, even that is, a full-bridge configuration Thus, the same effect as in the case of FIG. 1 can be obtained. Note that this full-bridge inverter 1
, Switches S ₂ and S ₅ and switches S ₃ and S ₄
Are turned on and off alternately as a set to generate a rectangular wave voltage between cd.

(Embodiment 2) FIG. 4 shows another embodiment of the present invention.
Show. In the case of this embodiment, the capacitor C_TwoTo the charge of
Pulse transformer PT for generating higher voltage pulse₁And
Switch S₁And the capacitor C_TwoBy the charge of
Pulse transformer PT that generates high-voltage pulses ₁’And Sui
Switch S₁’.

The operation of this embodiment is based on two pulse transformers P
T₁, PT₁'Secondary winding n₁, N ₁’Each
The voltage obtained by adding the high-voltage pulse
C₁Is simply applied to the high-pressure discharge lamp La via
Specifically, the operation is the same as that of the first embodiment,
The flow can be increased to improve startability. What
In this embodiment, the pulse transformer PT₁, PT
₁′ And the pulse transformer are divided into two,
The withstand voltage of the pulse transformer per unit is half that of the first embodiment.
The advantage is that it can easily solve the problem of insulation
There is.

[0024]

As described above, the present invention comprises an inverter for converting the voltage of a DC power supply into a rectangular wave voltage, and an igniter for superimposing a high-voltage pulse on the output of the inverter and applying the pulse to a high-pressure discharge lamp. The igniter generates a high-voltage pulse so that the polarity of the pulse having the maximum peak value is opposite to the rectangular wave output of the inverter. The igniter can be started up smoothly by increasing the push-in current, and the high-pressure discharge lamp can be started smoothly. There is no worry that the peak voltage of the pulse will increase.

[Brief description of the drawings]

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

FIG. 2 is an explanatory diagram showing the operation of the above.

FIG. 3 is a main part circuit diagram when an inverter has a full bridge configuration.

FIG. 4 is a circuit diagram showing an igniter according to another embodiment.

FIG. 5 is a schematic circuit diagram of a conventional example.

FIG. 6 is a circuit diagram showing a specific configuration of the igniter according to the first embodiment.

FIG. 7 is an operation explanatory diagram of the above.

FIG. 8 is an explanatory diagram of the reason why the pushing current is insufficient in the above.

FIG. 9 is an explanatory diagram of a lamp current actually flowing in the high-pressure discharge lamp according to the first embodiment.

FIG. 10 is an explanatory diagram showing the reason why an inverter that generates a rectangular wave output is used as the inverter.

[Explanation of symbols]

 1 Inverter 2 Igniter La High pressure discharge lamp

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-3-283394 (JP, A) JP-A-62-26792 (JP, A) JP-T6-6-500887 (JP, A) JP-T-Hei6- 500888 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) H05B 41/24-41/298

Claims (1)

(57) [Claims] 1. An inverter for converting a voltage of a DC power supply into a rectangular wave voltage, and an igniter for applying a high-voltage pulse to an output of the inverter and applying the high-voltage pulse to a high-pressure discharge lamp, wherein the igniter has a pulse having a maximum peak value. A discharge lamp lighting device characterized in that a high-voltage pulse is generated such that the polarity of the pulse is opposite to the rectangular wave output of the inverter.