JPH06243974A - High pressure discharge lamp lighting device - Google Patents

Abstract

PURPOSE:To prevent useless generation of a high pressure pulse from the second starting circuit. CONSTITUTION:A sufficient high pressure pulse is generated by the first starting circuit 2a so as to cause dielectric breakdown of a high pressure discharge lamp DL. A sufficient high pressure pulse is generated later than the high pressure pulse of the first starting circuit 2a by the second starting circuit 2b so as to maintain discharge of the high pressure discharge lamp DL. The fact that the dielectric breakdown is caused in the high pressure discharge lamp DL by the high pressure pulse of the first starting circuit 2a, is detected by a dielectric breakdown detecting circuit 3, and when the dielectric breakdown is caused, the second starting circuit 2b is operated.

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 having a starting circuit for starting a high pressure discharge lamp.

[0002]

2. Description of the Related Art FIG. 4 shows a high pressure discharge lamp lighting device having a general structure. In this high pressure discharge lamp lighting device, the commercial AC power supply AC is supplied to the high pressure discharge lamp DL via an inductor L ₁ as a ballast. The supply control of the AC power supply AC is performed by the power switch SW. The high-pressure discharge lamp DL needs to apply a high voltage at the time of starting. Therefore, the high pressure discharge lamp DL
A starting circuit unit 2 for applying a high voltage pulse is provided. The capacitor C ₀ connected to both ends of the AC power supply AC via the power switch SW prevents a high-voltage pulse generated in the starting circuit unit 2 from leaking to the power supply side, and is connected in parallel with the capacitor C _0. The resistor R ₀ is provided to rapidly discharge the charge stored in the capacitor C ₀ and improve the blocking effect for high voltage pulses.

In the starting circuit section 2, the inductor L ₁ as a ballast is also used to generate a high voltage pulse. After the high pressure discharge lamp DL is started by the starting circuit unit 2,
Lighting is maintained by the power supplied via the inductor L ₁ . Then, the high-pressure discharge lamp DL gradually becomes hot immediately after starting, and the pressure of the enclosed material becomes high, and the lighting state becomes stable.

Now, if the supply of power is stopped for some reason while the high-pressure discharge lamp DL is lit stably, the high-pressure discharge lamp DL is turned off. Immediately after the light is turned off in this way, the temperature becomes extremely high and the enclosed material is in a high pressure state. Therefore, even if a high voltage pulse is applied from the starting circuit unit 2, the high pressure discharge lamp DL is started and lit. It is not possible. In other words, in such a situation, unless the temperature of the high pressure discharge lamp DL is lowered and the pressure of the enclosed material is reduced, the high pressure discharge lamp DL cannot be restarted. That is, this type of high pressure discharge lamp DL has a problem that it is difficult to instantaneously relight the lamp.

However, a method of applying a high-voltage pulse having a wide pulse width (several tens of μsec) and a peak voltage of tens of kV, or a narrow pulse width (several hundreds of nsec) and a peak voltage of tens of kV According to the method of applying the high-voltage pulse of No. 1 at a cycle of several kHz, it is possible to restart and turn on the light. However, this causes a problem that the circuit configuration becomes complicated and the shape becomes very large.

As a discharge lamp lighting device provided with a starting circuit section 2 capable of improving this point and enabling an instantaneous restart, there is, for example, one proposed in Japanese Patent Laid-Open No. 62-88295. As shown in FIG. 5, this discharge lamp lighting device starts a high pressure discharge lamp DL, a stabilizing circuit unit 1 that supplies a lighting power source for maintaining lighting of the high pressure discharge lamp DL from an AC power supply AC, and a high pressure discharge lamp DL. And a starting circuit section 2 that operates.

The starting circuit section 2 is constructed by using a pulse transformer PT, and the pulse transformer PT is provided with two secondary windings n ₂ and n ₃ . And the starting circuit 2
Is composed of first and second starting circuits 2a and 2b which generate individual high voltage pulses. First starting circuit 2
a is composed of a secondary winding n ₂ , resistors R ₁ and R _2, and a switch element S _{1. The} resistance R ₁ and the switch element S ₁ are connected in parallel to the output of the stable circuit unit 1 and the resistance R ₁ and A switch element S ₁ is connected, and a secondary winding n ₂ with few windings, a capacitor C ₁ and a resistor R ₂ are connected in parallel to the switch element S ₁ .

The second starting circuit 2b has a secondary winding n.₃,
Anti-R₃, Capacitor C₂And switch element S₂Empty
Resistance R₃And capacitor C₂The output of the stabilization circuit unit 1
Connected in parallel to the capacitor C₂2 with many turns in parallel
Next winding n₃And switch element S₂Connect to and configure
It In the above starting circuit, the resistance R₁, R₂And secondary winding n
₂Through the capacitor C₂And charge the resistor R₃
Through the capacitor C₂To charge. And Conden
SA C₁The charge accumulated in the switch element S₁Break
When the overvoltage is reached, the switching element S₁Is on
, Secondary winding n₂Through the capacitor C₁Charge charge
To discharge rapidly. As a result, the pulse transformer PT
Primary winding n ₁A high voltage pulse is generated at both ends of. This and
The high voltage pulse of the mushroom causes the dielectric breakdown of the high pressure discharge lamp DL.
Pulse width is narrow enough and peak voltage is high.
ing.

After the charge of the capacitor C ₁ is discharged, an oscillating current flows through the path of the capacitor C ₁ , the secondary winding n ₂ , the switch element S ₁ , and the resistor R ₂ , and the oscillating current causes the switch to switch. The element S ₂ is triggered and the switch element S ₂ is turned on. In this way, the switch element S ₂
When is turned on, the electric charge charged in the capacitor C ₂ is rapidly discharged through the secondary winding n ₃ , and the pulse transformer PT
A high voltage pulse is generated at both ends of the primary winding n ₁ . The high-voltage pulse at this time has a wide pulse width and a low peak voltage that are sufficient to maintain discharge when dielectric breakdown occurs due to the high-voltage pulse generated in the secondary winding n ₂ . The high-voltage pulse generated in the second starting circuit 2b has a lower peak voltage than that of the high-voltage pulse generated in the first starting circuit 2a. The high-voltage pulse to be performed will be referred to as a low-voltage pulse in the following description.

FIG. 6 shows the structure of a general stabilizing circuit unit 1, which is composed of a capacitor C ₀ , a resistor R ₀ and an inductor L ₁ as a ballast.

[0011]

However, according to the method described above, the low voltage pulse is always generated after the high voltage pulse is applied. That is, there is a waste of applying the low-voltage pulse even when the high-voltage discharge lamp DL does not cause dielectric breakdown due to the high-voltage pulse. Moreover, if the low-voltage pulse is applied while the high-pressure discharge lamp DL is not causing dielectric breakdown, there is a problem that the secondary voltage becomes high. For this reason, it is necessary to take measures such as limiting the pulse width of the low-voltage pulse, etc., and there is a problem that the degree of freedom in design is reduced.

The present invention has been made in view of the above points, and an object thereof is to light a high pressure discharge lamp capable of preventing wasteful generation of a high voltage pulse from the second starting circuit. To provide a device.

[0013]

In order to achieve the above object, the present invention provides a high pressure discharge lamp, a first starting circuit for generating a high voltage pulse sufficient to cause dielectric breakdown of the high pressure discharge lamp, and a first starting circuit. Second high-voltage pulse that is sufficient to maintain the discharge of the high-pressure discharge lamp after the high-voltage pulse of the starting circuit of
And a dielectric breakdown detection circuit for detecting that dielectric breakdown has occurred in the high-pressure discharge lamp with a high-voltage pulse by the first starting circuit and operating the second starting circuit when dielectric breakdown occurs, And a stabilizing circuit section for maintaining lighting of the discharge lamp.

[0014]

According to the present invention, as described above, the first starting circuit detects that a high-voltage pulse causes dielectric breakdown in the high-pressure discharge lamp, and when the dielectric breakdown occurs, the second starting circuit operates. By providing the breakdown detection circuit, the high-voltage pulse generated by the second starting circuit is generated when the dielectric breakdown occurs due to the high-voltage pulse generated by the first starting circuit. That is, when the high-voltage pulse generated by the first starting circuit does not cause dielectric breakdown, the high-voltage pulse generated by the second starting circuit is not generated. This prevents wasteful application of the high-voltage pulse by the second starting circuit to the high-pressure discharge lamp when the high-pressure discharge lamp does not cause dielectric breakdown.

[0015]

【Example】

(Embodiment 1) FIG. 1 shows an embodiment of the present invention. This embodiment is based on the circuit shown in FIG. 6 described in the section of the prior art. The feature of this embodiment is that it detects the occurrence of dielectric breakdown in the high-pressure discharge lamp DL from the lamp current and performs insulation. The second starting circuit 2b when it is detected that a breakdown has occurred
The dielectric breakdown detection circuit 3 for turning on the switch element S ₂ of is provided.

2A is a high-voltage pulse applied to the high-pressure discharge lamp DL by the first starting circuit 2a, and B is a low-voltage pulse applied to the high-pressure discharge lamp DL by the second starting circuit 2b. is there. The dielectric breakdown detection circuit 3 detects the dielectric breakdown as follows. That is, the high pressure discharge lamp D
When dielectric breakdown occurs at L, a rush current larger than that during steady lighting flows through the high pressure discharge lamp DL. Therefore, the dielectric breakdown is detected by detecting the rush current.

As described above, by controlling the application of the low-voltage pulse for maintaining the discharge of the high-pressure discharge lamp DL depending on whether or not the discharge lamp La has caused the dielectric breakdown, the high-pressure discharge lamp DL is controlled.
It is possible to prevent the low-voltage pulse from being unnecessarily applied to the high-pressure discharge lamp DL when the dielectric breakdown does not occur. Moreover,
When the high-pressure discharge lamp DL does not cause a dielectric breakdown, the low-voltage pulse is not applied to the high-pressure discharge lamp DL, so it is safe, and there is no need to limit the pulse width of the low-voltage pulse in consideration of safety, and the design is free. It has the advantage of increasing the frequency.

(Embodiment 2) FIG. 3 shows another embodiment of the present invention. In this embodiment, as a first starting circuit 2a, the pulse transformer PT, inductor L _2, are constituted by a capacitor C ₁ and the switch element S _1. Here, the inductor L ₂ is used instead of the charging resistor. Second starting circuit 2b, Yes using inductor L ₁ as stabilizer instead of the pulse transformer, are constituted by a capacitor C ₁ and a switch element S _2. Then, the switch element S ₁ of the first starting circuit 2a is configured to be turned on by the output of the timer circuit 4 which measures a certain time from the power supply time (power switch SW is turned on).

Now, when a fixed time of the timer circuit 4 has passed since the power was turned on, the switch element S ₁ is turned on by the output of the timer circuit 4 at this time, and a high voltage pulse is generated. Then, the high voltage pulse causes a dielectric breakdown in the high pressure discharge lamp DL, and when the rush current is detected by the dielectric breakdown detecting circuit 3, the switch element S ₂ is turned on by the output of the dielectric breakdown detecting circuit 3 and the capacitor C ₁ becomes By being discharged, a low voltage pulse is generated across the inductor L ₁ . Thereby, the discharge of the high pressure discharge lamp DL is maintained. After that, lighting power is supplied from the stabilizing circuit unit 1 to the high-pressure discharge lamp DL,
Lighting of the high pressure discharge lamp DL is maintained.

Also in this embodiment, when the high-voltage pulse does not cause dielectric breakdown in the high-pressure discharge lamp DL, the low-voltage pulse is not wastefully generated.

[0021]

As described above, the present invention provides a high pressure discharge lamp,
A first starting circuit that generates a sufficient high-voltage pulse that causes insulation breakdown of the high-pressure discharge lamp, and a high-voltage pulse that is sufficient to maintain the discharge of the high-pressure discharge lamp after the high-voltage pulse of the first starting circuit. A second starting circuit, and a dielectric breakdown detecting circuit for detecting that the high voltage pulse causes a dielectric breakdown in the high-pressure discharge lamp by the first starting circuit and operating the second starting circuit when the dielectric breakdown occurs. Since the high-voltage discharge lamp is provided with a stabilizing circuit section for maintaining lighting, the high-voltage discharge lamp does not generate a high-voltage pulse when the high-voltage pulse generated by the first starting circuit does not cause dielectric breakdown. It is possible to prevent wasteful application of the high-voltage pulse by the second starting circuit to the high-pressure discharge lamp when the dielectric breakdown does not occur. Moreover, since the low-voltage pulse is not applied in the state where the high-pressure discharge lamp does not cause the dielectric breakdown, it is not necessary to take measures such as limiting the pulse width of the low-voltage pulse.
There is less design freedom.

[Brief description of drawings]

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

FIG. 2 is a waveform diagram of a lamp voltage to which a high-voltage pulse according to the same is applied.

FIG. 3 is a circuit diagram of another embodiment.

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

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

FIG. 6 is a circuit diagram of still another conventional example.

[Explanation of symbols]

 1 Stabilization Circuit Section 2 Starting Circuit Section 2a First Starting Circuit 2b Second Starting Circuit 3 Dielectric Breakdown Detection Circuit DL High Pressure Discharge Lamp

Claims (1)

[Claims] 1. A high-pressure discharge lamp, and a first starting circuit for generating a high-voltage pulse sufficient to cause dielectric breakdown of the high-pressure discharge lamp,
A second starting circuit that generates a high-voltage pulse sufficient to maintain the discharge of the high-pressure discharge lamp after the high-voltage pulse of the first starting circuit, and a dielectric breakdown of the high-pressure discharge lamp with the high-voltage pulse by the first starting circuit. A high-voltage discharge detection circuit that detects the occurrence of a high-voltage discharge lamp and activates the second starting circuit when a high-voltage discharge lamp occurs, and a stabilizing circuit unit that maintains lighting of the high-pressure discharge lamp. Discharge lamp lighting device.