JPH05258883A - Lighting device for discharge lamp - Google Patents

Abstract

PURPOSE:To eliminate the restriction of the selection of the constant of a main lighting circuit by setting the synthetic impedance of an LC serial resonance circuit and the impedance of an ignitor sufficiently high. CONSTITUTION:An inverter IN switches at least one of switching elements Q1, Q2 to convert the DC power voltage into the high-frequency voltage. The elements Q1, Q2 form an oscillating resonance circuit together with capacitors C1, C2 when they are closed. The synthetic impedance of an LC serial resonance circuit is set sufficiently high against the oscillation frequency of the oscillation circuit of an ignitor IG. The impedance of the circuit including the impedance element of the ignitor IG connected in parallel with a discharge lamp DL is set sufficiently large against the lighting frequency of the discharge lamp DL. When the discharge lamp DL is ordinarily lighted, the voltage not affecting the elements Q1, Q2 and the resonance circuit is used. The ignitor IG gives no restriction on the selection of the constant of a main lighting circuit, and no effect in the electric capacity is given to the elements Q1, Q2.

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 device which is equipped with an igniter for starting a discharge lamp which requires a high voltage at the time of starting and which turns on the discharge lamp at a high frequency.

[0002]

2. Description of the Related Art A conventional discharge lamp lighting device of this type is shown in FIG. In this discharge lamp lighting device, a DC voltage obtained by rectifying and smoothing an AC power supply V ₁ with a diode bridge DB ₁ as a full-wave rectifier and a smoothing capacitor C ₀ is converted into a high frequency voltage by an inverter IN, and the output of this inverter IN is output. Therefore, a high-frequency alternating current is passed through the discharge lamp DL to light it.

As the inverter IN of the discharge lamp lighting device, transistors Q ₁ and Q ₂ as switching elements are connected in series at both ends of a smoothing capacitor C ₀ , and a capacitor C ₂ for cutting a direct current is provided at both ends of the transistor Q _2. A current limiting choke L ₁ and a capacitor C ₁ which form a series resonance circuit are connected via a discharge lamp DL at both ends of the capacitor C _1.
A so-called half-bridge type in which is connected is used.
Further, diodes D ₁ and D ₂ for freewheeling are connected in antiparallel to the respective transistors Q ₁ and Q ₂ , and the control circuit B controls switching. This inverter IN
Then, the discharge lamp DL is started by the voltage of the capacitor C ₁ boosted by the resonance of the series resonance circuit.

In the discharge lamp lighting device having the above structure, the frequency of the rectangular wave power supply V _R generated at both ends of the series resonance circuit (including the discharge lamp DL) at the time of steady lighting is set so that the rated current flows through the discharge lamp DL. Has been done. Therefore, in order to boost the voltage across the capacitor C ₁ at the time of no load (not the point of the discharge lamp DL) to an optimum voltage to start the discharge lamp DL, the frequency of the square wave power source V _R, i.e. the transistor Q It is necessary to change the switching frequencies of ₁ and Q ₂ (specifically, to bring the switching frequencies of the transistors Q ₁ and Q ₂ close to the resonance frequency of the series resonance circuit). Therefore, there is a problem that the circuit configuration of the control circuit B becomes complicated.

Meanwhile, when close to the resonant frequency of the series resonant circuit the switching frequency of the transistor Q _1, Q ₂ as described above, the switching frequency of the transistor Q _1, Q ₂ are in accordance with the approach to the resonant frequency of the series resonant circuit , The currents flowing through the transistors Q ₁ and Q ₂ increase. Here, the current flowing through the transistor Q _1, Q _2, it is constrained by the electrical capacitance of the transistor Q _1, Q _2, naturally limited to the extent that boosts the voltage across the capacitor C ₁ is caused. Therefore, in the case of the discharge lamp DL that requires a higher voltage for starting, the method for starting the discharge lamp lighting device cannot be applied.

Therefore, when starting the discharge lamp DL which requires a higher voltage for starting, it is conceivable to secure the starting voltage of the discharge lamp DL by using an igniter. FIG. 5 shows the discharge lamp lighting device of FIG. 4 provided with an igniter IG. Igniter I in this discharge lamp lighting device
G is a pulse transformer PT ₁ in which the secondary winding N ₂ is inserted in series with the discharge lamp DL, and a series circuit composed of a capacitor C ₃ , a resistor R ₁ and a diode D ₃ connected to both ends of the capacitor C _1. , A voltage responsive switching element Q ₃ connected across the capacitor C ₃ via the primary winding N ₁ of the pulse transformer PT ₁ .

In this igniter IG, the capacitor C ₁
With the voltage across both ends of the capacitor as a power source, a capacitor C ₃ , a resistor R ₁ ,
The current that flows in the path of the diode D ₃ and the capacitor C ₃
There is charged, the charging voltage of the capacitor C ₃ is, when it reaches the break voltage of the switching element Q _3, and conducts switching element Q _3, a capacitor C _3, 1 winding N _1, the switching element Q ₃ A steep current flows through the path, and a voltage boosted and induced in the secondary winding N ₂ by this current is applied to the discharge lamp DL to start the discharge lamp DL.

[0008]

By the way, in the case of this kind of igniter IGN, the turn-off characteristic of the switching element Q ₃ and the current rising characteristic at the time of turn-on (usually di /
(referred to as dt), or due to constraints such as the current peak value, the capacitance value of the capacitor C ₃ and the primary winding N
The inductance value of ₂ must be a certain value or more. Here, the inductance value of the secondary winding N _2, the primary winding N ₁ of the inductance value (n ₂ /
n ₁ ) ² times (where n ₁ and n ₂ are windings N ₁ and N _{2 respectively)}
Therefore, when the inductance value of the primary winding N ₂ becomes a certain value or more, the inductance value of the secondary winding N ₁ becomes a large value.

In the case of the discharge lamp lighting device, since the secondary winding N _{2 of the} igniter IG is inserted in the current path of the discharge lamp DL (inserted in series with the discharge lamp DL), it is discharged. There is a problem that the constant design of the electric light DL during steady lighting is greatly affected, and it becomes a constraint on the design of the series resonant circuit. This point will be described when the discharge lamp DL is a high pressure discharge lamp. In a discharge lamp lighting device for lighting a high pressure discharge lamp, in order to avoid a so-called acoustic resonance phenomenon peculiar to the high pressure discharge lamp, a frequency higher by one digit or more than a lighting frequency (tens of kHz) conventionally used in a fluorescent lamp or the like. The discharge lamp DL is constantly lit at (several hundred kHz). In such a discharge lamp lighting apparatus, the use of the secondary winding N ₂ of the inductance value becomes necessary than the design of the igniter IG, a secondary winding N ₂ relative inductance of the current-limiting choke L ₁
There is a risk that the inductance value of will become extremely large and there will be no comprehensive design point.

The present invention has been made in view of the above points, and an object of the present invention is to limit the constant selection of the main lighting circuit by the igniter and to reduce the capacitance of the switching element of the main lighting circuit. An object of the present invention is to provide a discharge lamp lighting device that does not cause any influence.

[0011]

According to the present invention, in order to achieve the above object, a DC power supply and at least one switching element are switched to convert the voltage of the DC power supply into a high frequency voltage, and an LC series resonance is output. A main lighting circuit is composed of an inverter that includes a circuit and a discharge lamp that is lit by the output of this inverter and that requires a high voltage at the time of starting.The main lighting circuit is equipped with an igniter that starts the discharge lamp, a capacitor that accumulates electric charge, and this capacitor. A voltage responsive switching element that closes when the voltage across both ends of the switch reaches a predetermined voltage, a first inductance element that forms an oscillating circuit with a capacitor when the switching element is closed, and a first inductance element. The voltage induced by the resonance current that is electromagnetically coupled and flows in the closed circuit is required directly or by impedance to the discharge lamp. The igniter is composed of the second inductance element applied via the igniter, and at least the voltage of the main lighting circuit that does not affect the switching element and the LC series resonance circuit at the time of steady lighting of the discharge lamp is used as the operating power source of the igniter. , The combined impedance of the LC series resonant circuit is set sufficiently higher than the vibration frequency of the igniter's vibration circuit, and the impedance of the circuit including the second inductance element of the igniter connected in parallel with the discharge lamp is released. It is set sufficiently high for the lighting frequency of the electric lamp.

[0012]

The present invention has the above-mentioned configuration,
The igniter does not substantially affect the steady lighting of the discharge lamp to prevent the igniter from restricting the selection of constants for the main lighting circuit. As the operating power supply of the igniter, at least the switching element and L
The voltage of the main lighting circuit that does not affect the C-series resonance circuit is used to prevent the switching element from being capacitively affected.

[0013]

【Example】

(Embodiment 1) FIG. 1 shows an embodiment of the present invention. The basic configuration of the discharge lamp lighting device of the present embodiment is the same as that of FIG. 4, and the same components are designated by the same reference numerals and the description thereof is omitted. In the following description, the circuit unit configured as shown in FIG. 4 is called a main lighting circuit. In the discharge lamp lighting device of this embodiment, the discharge lamp DL is connected to both ends of the capacitor C ₁ of the main lighting circuit in FIG. 4 via the inductor L ₂ . here,
The inductor L ₂ has a smaller inductance value than at least the current limiting choke L ₁ and has a value in a range that does not substantially affect the overall operation of the main lighting circuit when the discharge lamp DL is steadily lit. Also, if this inductor L
By providing the _2, even if some differences in characteristics between 4 has occurred, it current limiting choke L ₁ and Inkuta which can be compensated by a slight correction of the values of the capacitors C ₁ L ₂
Select. Further, in the igniter IG of this embodiment, the diode D ₃ , the resistor R ₁ and the capacitor C ₃ are connected in series at both ends of the smoothing capacitor C ₀ , and the primary winding N of the pulse transformer PT ₁ is provided at both ends of the capacitor C _{3. 1} and a voltage responsive switching element Q ₃ are connected. The secondary winding N ₂ of the pulse transformer PT ₁ is connected to both ends of the discharge lamp DL via the capacitor C ₄ .

In the above igniter IG, when the switching element Q ₃ is closed, an oscillating current flows through a closed circuit composed of the capacitor C ₃ , the switching element Q ₃ and the primary winding N ₁ . Here, the frequency of the oscillating current is set so that the impedance of the series circuit of the inductor L ₂ and the capacitor C ₁ and the impedance of the series circuit of the inductor L ₂ , the current limiting choke L ₁ and the capacitor C ₂ are sufficiently high. It is set low. Therefore, the voltage induced in the secondary winding L ₂ by the oscillating current is applied to the discharge lamp DL via the capacitor C ₄ , and the discharge lamp DL can be started.

Further, in this embodiment, the combined impedance of the series circuit of the secondary winding N ₂ and the capacitor C ₄ is set to be sufficiently large with respect to the lighting frequency of the discharge lamp DL. Accordingly, after the discharge lamp DL is steadily turned on,
It is possible that the igniter IG does not substantially affect the main lighting circuit. Here, if the impedance of the secondary winding N ₂ is sufficiently large with respect to the lighting frequency, the capacitor C ₄ is not always necessary.

By the way, the above configuration limits the conventional commercial power source.
Fluorescent lamp filler via choke coil as flow element
Connection to the power supply side of the
The gnita was connected to the non-power supply side of the filament of the fluorescent lamp.
Looks similar to. However, in the case of this fluorescent lamp lighting device,
Secondary winding N₂The impedance of the
It needs to be lowered to the minute. This is greater than the lamp current
This is because a fine preheating current must be applied. this
On the other hand, the secondary winding N of the present embodiment₂(Capacitor C_FourTo
Impedance (including) is supplied from the inverter IN
It is completely different in that it is set sufficiently high for the power supply frequency
It In addition, the current limiting element consists of a choke coil and a capacitor.
Considering a so-called advanced lighting circuit, the primary winding N₁And
C Densa C ₃The vibration frequency of the closed circuit consisting of
Although it is sufficiently higher than the lighting frequency of the road, this implementation
In the example, the point is low enough to be completely opposite.

With the above arrangement, only the inductor L ₂ is newly added to the main lighting circuit in FIG. 4, and the inductance value of the inductor L ₂ is set so as to have almost no influence on the operation of the main lighting circuit. Since the igniter IG does not substantially affect the main lighting circuit after the discharge lamp DL is steadily lit, the igniter IG
, The constant of the main lighting circuit does not need to be changed, so that there is no restriction on the constant selection of the inverter IN as described with reference to FIG. Further, since the energy for obtaining the high voltage for starting is obtained without utilizing the vibration of the resonance circuit composed of the switching elements Q ₁ and Q ₂ , the current limiting choke L ₁ and the capacitor C ₁ , the switching element Q ₁ , Q
₂ does not affect the capacitance.

(Embodiment 2) FIG. 2 shows that after the discharge lamp DL is turned on.
In the embodiment configured to stop the operation of the igniter IG
Yes, in the above embodiment, the capacitor C₃As a power source for charging
Smoothing capacitor C₀While using the voltage of
In the case of this embodiment, the lamp voltage of the discharge lamp DL is used.
is doing. However, the lamp voltage in this case is substantially
C Densa C ₁It can be thought of as the voltage across. Where the above
C Densa C₁Voltage of the discharge lamp DL lights up when there is no load
The voltage will be higher than the time. Therefore, switch only when there is no load.
Touching element Q₃Switch so that it can be closed.
Element Q₃If you set the response voltage of
It is possible to stop the operation of the igniter IG after lighting.
It Even after the discharge lamp DL is turned on, the secondary winding N₂Is contact
Continued, but this secondary winding N₂Is the lighting frequency
Since it has a high impedance with respect to the discharge lamp DL,
After lighting, the igniter IG is practically disconnected from the inverter IN.
It is safe to think that they will be separated.

(Embodiment 3) FIG. 3 also shows an embodiment in which the operation of the igniter IG is stopped after the discharge lamp DL is turned on. In this embodiment, when the operation of the igniter IG is stopped, the secondary winding is used. It is characterized in that the line N ₂ is separated from both ends of the discharge lamp DL, and as in the case of the second embodiment, the discharge lamp D is
If the secondary winding N ₂ remains connected even after L is lit, this is applied in the case where the lighting of the discharge lamp DL is affected in some way. In the case of the present embodiment, when the voltage across the capacitor C ₁ drops when the discharge lamp DL is lit, the voltage responsive switching element Q ₄ that opens is set to 2
The secondary winding N ₂ and the capacitor C ₄ are connected in series with each other so that the secondary winding N ₂ is disconnected when the discharge lamp DL is turned on.

[0020]

As described above, the present invention provides a DC power supply, an inverter that switches at least one switching element to convert the voltage of the DC power supply into a high frequency voltage, and includes an LC series resonance circuit at the output, and this inverter. The main lighting circuit is composed of a discharge lamp that is lit by the output of the discharge lamp and requires a high voltage at startup, an igniter that starts the discharge lamp is provided, a capacitor that accumulates electric charge, and the voltage across this capacitor reaches a specified voltage. A voltage responsive switching element that closes when closed, a first inductance element that forms a vibrating circuit together with a capacitor when the switching element is closed, and the closed circuit electromagnetically coupled to the first inductance element. Second inductor for applying a voltage induced by a resonance current flowing in the discharge lamp directly or via an impedance element The igniter is composed of a tans element and a voltage of the main lighting circuit that does not affect the switching element and the LC series resonant circuit at least during steady lighting of the discharge lamp is used as an operating power source of the igniter to synthesize the LC series resonant circuit. The impedance is set sufficiently higher than the vibration frequency of the igniter's vibration circuit, and the impedance of the circuit including the second inductance element of the igniter connected in parallel with the discharge lamp is sufficient for the lighting frequency of the discharge lamp. Because it is set to high,
The igniter can be configured so that it does not substantially affect the steady lighting of the discharge lamp.Therefore, the igniter does not impose any restrictions on the selection of constants for the main lighting circuit. Since the voltage of the main lighting circuit that does not affect the element and the LC series resonance circuit is used, there is an advantage that the switching element is not affected in terms of electric capacitance.

[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 a circuit diagram of still another embodiment.

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

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

[Explanation of symbols]

IN inverter IG igniter DL discharge lamp Q _1, Q ₂ switching element Q ₃ switching elements L ₁ current limiting choke L ₂ inductor C _1, C ₃ condenser N ₁ 1 winding N ₂ 2 winding

Claims (1)

[Claims] 1. A DC power supply, an inverter that switches at least one switching element to convert the voltage of the DC power supply to a high-frequency voltage, and includes an LC series resonance circuit in the output, and an inverter that is turned on by the output of the inverter and is high at the time of starting. A main lighting circuit is composed of a discharge lamp that requires a voltage, an igniter that starts the discharge lamp is provided, a capacitor that stores electric charge, and a voltage response that closes when the voltage across the capacitor reaches a specified voltage. Type switching element, a first inductance element that forms an oscillating circuit together with a capacitor when the switching element is closed, and is induced by a resonance current that is electromagnetically coupled to the first inductance element and that flows in the closed circuit. With the second inductance element that applies a voltage to the discharge lamp directly or through the impedance element, The igniter is configured to use the voltage of the main lighting circuit that does not affect the switching element and the LC series resonant circuit at least during steady lighting of the discharge lamp as the operating power source of the igniter, and the combined impedance of the LC series resonant circuit is used as the igniter's combined impedance. Set sufficiently high for the vibration frequency of the vibration circuit, and set the impedance of the circuit including the second inductance element of the igniter connected in parallel to the discharge lamp sufficiently high for the lighting frequency of the discharge lamp. Discharge lamp lighting device characterized by comprising.