JPH06140178A - Discharge lamp lighting device - Google Patents

Abstract

PURPOSE:To attain miniaturization and cost down without setting switching waveform to unpreferable leading phase mode. CONSTITUTION:The DC circuit of a capacitor C1 and the primary winding of a leakage transformer T1 is connected between the middle point of switching elements Q1, Q2 and the middle point of capacitors C2, C3. The leakage inductance of the leakage transformer T1 is equivalently inserted in series to a discharge lamp 1. Since the switching waveform never become leading phase mode, and to conventionally used inductance is required, thus, miniaturization and cost down can be attained.

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 for lighting a discharge lamp.

[0002]

2. Description of the Related Art Conventionally, as a device for lighting a discharge lamp,
Inverter lighting devices are well known. Figure 8 takes
The conventional discharge lamp lighting device is shown. In FIG.
Current source E₀Two switching elements in parallel to
Q₁, Q ₂Series circuit and two capacitors C₂, C₃
A series circuit of is connected, and at the midpoint of each, for resonance
Chalk L₁And resonance capacitor C₁Series resonance circuit
Are connected.

A primary winding of a transformer T ₂ is connected in parallel to the choke L ₁ or the capacitor C ₁ , and a discharge lamp 1 is connected to a secondary winding of the transformer T ₂ to discharge by a so-called half bridge circuit. Electric lighting devices are well known. In FIG. 8, capacitors C ₂ , C ₃ are coupling capacitors, and diodes D ₁ ,
D ₂ is connected in antiparallel to the switching elements Q ₁ and Q ₂ .

Here, in the circuit of FIG. 8, when the discharge lamp 1 is turned on, the impedance of the discharge lamp 1 is lowered,
The inductance component of the choke L ₁ connected to the primary side of the transformer T ₂ is reduced, and the resonance condition is determined by the capacitor C ₁ , resulting in an unfavorable switching waveform in the phase advance mode. To improve it, in the circuit shown in FIG. 9, the inductance L ₂ in series is provided to the discharge lamp l, or its measures, the inductance of Fig. 9 a leakage transformer T ₁ as shown in FIG. 10 L ₂
It was used instead of, and the switching waveform was prevented from entering the phase advance mode by devising a method of eliminating the inductance L ₂ .

FIG. 11 shows that when a half-wave discharge occurs at the end of the life of the discharge lamp l, the direct current component of the lamp current is changed to the capacitor C ₅
It has been cut with to eliminate abnormal oscillation.

[0006]

Although there are the conventional circuit examples as described above, the choke L ₁ and the leakage transformer T _{1 are provided.}
Alternatively, there are two or more magnetic parts of the transformer T ₂ , and in addition to FIG.
In addition, since there are three magnetic parts having the inductance L ₂ , the lighting device itself becomes large and the cost is high.

Therefore, as shown in FIG. 12, the transformer T
_{There is one in which} the resonance circuit of the primary winding of No. ₂ and the capacitor C ₁ is operated, but in this circuit, when the discharge lamp 1 is turned on, the switching condition is advanced as described above. Mode, switching elements Q ₁ , Q
_It is an unfavorable waveform in which _two simultaneous ONs are likely to occur.

As a countermeasure against this, as shown in FIG. 13, when an inductance L ₂ is inserted in series with the discharge lamp l,
It is out of the original purpose of downsizing, and it is a fall. The present invention has been provided in view of the above points, and provides a discharge lamp lighting device for achieving size reduction and cost reduction without setting a switching waveform in an unfavorable phase advance mode. Is.

[0009]

SUMMARY OF THE INVENTION The present invention comprises a DC power supply,
The first and second switching elements connected in series to the DC power supply in parallel and the series circuit of the first and second capacitors connected in parallel to the DC power supply are provided.
A series circuit of the third capacitor and the primary winding of the leakage transformer is connected between the midpoint of the second switching element and the midpoint of the first and second capacitors, and is connected to the secondary side of the leakage transformer. A discharge lamp is connected.

Further, according to a second aspect of the present invention, a series circuit of the first capacitor, the third capacitor and the primary winding of the leakage transformer is connected in parallel with the first or second switching element. Further, according to a third aspect of the present invention, the midpoints of the third and fourth diodes, which are anti-series connected in parallel with the DC power source, are connected to a predetermined position of the primary winding of the leakage transformer.

[0011]

According to claim 1 of the present invention, the leakage inductance of the leakage transformer is equivalently inserted in series with the discharge lamp, so that the switching waveform does not enter the phase advance mode, and moreover Since there is no need for inductance as described above, size reduction and cost reduction can be achieved.

Further, according to the second aspect, the circuit can be simplified and the size and cost can be reduced without setting the switching waveform in an unfavorable phase advance mode. Furthermore, in the third aspect, the diode can clamp the high voltage generated in the primary winding of the leakage transformer when the discharge lamp is abnormal to the voltage of the DC power supply, and reduce the stress of the switching element. Moreover, miniaturization and cost reduction can be achieved without setting the switching waveform in an unfavorable phase advance mode.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a circuit diagram of the present invention. This circuit is shown in Figure 12.
The leakage transformer T ₁ is connected in place of the transformer T ₂ of the conventional circuit example. Leakage transformer T ₁
The leakage inductance of is equivalently inserted in series to the discharge lamp l, so that the switching waveform which has been a problem does not become the phase advance mode, and the inductance L ₂ of the conventional circuit example of FIG. Therefore, size reduction and cost reduction can be achieved.

FIG. 2 is a specific circuit diagram of FIG. The resistor R ₃ , the diac Q ₃ , and the capacitor C ₄ constitute the starting circuit 1, and the starting signal is given to the switching element Q ₂ . Further, two discharge lamps l ₁ and l ₂ are connected in series. The switching elements Q ₁ and Q ₂ are
It is a semi-self-excited circuit biased by the voltage induced in the secondary and tertiary windings of the current transformer CT. Resistance R ₁ , R
Reference numeral ₂ is for limiting the base current of the switching elements Q ₁ and Q ₂ .

Further, two discharge lamps l ₁ and l ₂ are connected to the secondary side of the leakage transformer T _{1, and} a current is supplied to each filament by windings n ₃ , n ₄ and n _5. It has become so. (Second Embodiment) FIG. 3 shows a second embodiment. The difference from FIG. 1 is that there is no capacitor C ₃ and the capacitor C ₁ and the leakage transformer T ₁ are replaced. The operation is almost the same as in the case of FIG.

That is, the switching element Q₁Is on
Time is capacitor C₂Power source₂→
Switching element Q₁→ Capacitor C₁And leakage
Lance T₁Series circuit → capacitor C₂And resonance current flows
The loop is the same in both FIG. 1 and FIG. However,
Touching element Q₂When the power turns on, the
SA C₃To the power supply and the capacitor C₃→ Leakage transformer
T₁And capacitor C₁Series circuit → Switching element Q
₂→ Capacitor C₃And the resonance current flows,
In case of 3, DC power supply E₀Power source, DC power source E₀→
Indexer C₂→ Leakage transformer T₁And capacitor C
₁Series circuit → Switching element Q₂→ DC power supply E ₀When
The difference is that the resonance current flows, but the operation is almost the same.
is there.

(Embodiment 3) Embodiment 3 is shown in FIG. Figure 1
₃ is that a capacitor C ₅ is inserted in series with the discharge lamp l. This is for preventing the discharge lamp 1 from becoming a half-wave discharge at the end of its life and being in an abnormal mode, and for cutting the direct current component. FIG. 5 shows a specific circuit diagram thereof. 2 is different from that of the leakage transformer T _{1 in} FIG.
Although the circuit on the secondary side is different, the two discharge lamps l ₁ and l ₂ are connected in series, but the filament winding n
Instead of _{3 to} n ₅ , the preheating capacitors C ₆ and C ₇ are 4
This is that the two filaments are inserted in series as shown in FIG. 5, and the capacitor C ₅ is inserted in series in the discharge lamps l ₁ and l ₂ . Needless to say, T ₁ is a leakage transformer.

In this circuit, the switching waveform is
Not only does it not go into phase advance mode,
l₁, L₂It is possible to eliminate the abnormal mode at the end of the life of
It can be done. (Fourth Embodiment) FIG. 6 shows a fourth embodiment. Differences from Figure 1
Is the leakage transformer T₁Middle tap of the primary winding
And the clamp diode D₃, D_FourSeries circuit to DC
Power E₀Which are connected in anti-parallel to the discharge lamp l
Leakage transformer T at abnormal time ₁Occurs in the primary winding of
DC voltage E₀Clamp to the voltage of the switch
Element Q₁, Q₂Can reduce the stress of
It

FIG. 7 showing the fifth embodiment has the same effect.

[0020]

As described above, the present invention provides a DC power supply, first and second switching elements connected in series to the DC power supply in parallel, and first and second switching elements connected in parallel to the DC power supply.
And a series circuit of a second capacitor,
A series circuit of the third capacitor and the primary winding of the leakage transformer is connected between the middle point of the switching element and the middle point of the first and second capacitors, and the discharge lamp is connected to the secondary side of the leakage transformer. Since the leakage inductance of the leakage transformer is equivalently inserted in series with the discharge lamp, the switching waveform will not be in the phase-advancing mode, and the inductance will not be the same as in the past. Since there is no need, it is possible to achieve the effects of downsizing and cost reduction.

According to a second aspect of the present invention, a series circuit of a first winding of a leakage transformer is connected in parallel with the first or second switching element. Thus, the circuit can be simplified, and the size and cost can be reduced without setting the switching waveform in an unfavorable phase advance mode.

Furthermore, in the present invention, the midpoint of the third and fourth diodes, which are anti-series connected in parallel with the DC power source, is connected to the predetermined point of the primary winding of the leakage transformer. The diode can clamp the high voltage generated in the primary winding of the leakage transformer when the discharge lamp is abnormal to the voltage of the DC power supply, and reduce the stress of the switching element. Moreover, miniaturization and cost reduction can be achieved without setting the switching waveform in an unfavorable phase advance mode.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a discharge lamp lighting device according to an embodiment of the present invention.

FIG. 2 is a specific circuit diagram of FIG. 1 above.

FIG. 3 is a circuit diagram of a second embodiment of the above.

FIG. 4 is a circuit diagram of a third embodiment of the above.

5 is a specific circuit diagram of FIG. 4 above.

FIG. 6 is a circuit diagram of Embodiment 4 of the above.

FIG. 7 is a circuit diagram of a fifth embodiment of the above.

FIG. 8 is a circuit diagram of a conventional discharge lamp lighting device.

FIG. 9 is a circuit diagram of another conventional example.

FIG. 10 is a circuit diagram of still another conventional example.

FIG. 11 is a circuit diagram of another conventional example.

FIG. 12 is a circuit diagram of still another conventional example.

FIG. 13 is a circuit diagram of still another conventional example.

[Explanation of symbols]

l Discharge lamp E ₀ DC power supply Q ₁ First switching element Q ₂ Second switching element C ₂ First capacitor C ₃ Second capacitor C ₁ Third capacitor T ₁ Leakage transformer

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Shinkazu Miki 1048 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Works Co., Ltd.

Claims (3)

[Claims] 1. A direct current power supply, first and second switching elements connected in parallel to the direct current power supply in series, and a series circuit of first and second capacitors connected in parallel to the direct current power supply. A series circuit of a primary winding of a leakage transformer is connected between the midpoint of the first and second switching elements and the midpoint of the first and second capacitors, A discharge lamp lighting device characterized in that a discharge lamp is connected to the secondary side of the transformer. 2. The series circuit of the first capacitor, the third capacitor, and the primary winding of the leakage transformer is connected in parallel with the first or second switching element. Discharge lamp lighting device. 3. The midpoint of the third and fourth diodes, which are anti-series connected in parallel with the DC power source, and the predetermined location of the primary winding of the leakage transformer are connected. Discharge lamp lighting device.