JPH0629916Y2 - Discharge lamp lighting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a discharge lamp lighting device for lighting a discharge lamp at a high frequency.

[Prior Art] Conventionally, as a discharge lamp lighting device of this type, there has been one as shown in Fig. 11 (Japanese Patent Application No. 60-125640).
That is, a DC power source obtained by rectifying the AC power source AC by the diode bridge DB is applied to the high frequency oscillation circuit OSC, and the discharge lamp EL is lit at a high frequency by the output of the high frequency oscillation circuit OSC. Here, the high frequency oscillator circuit O
SC includes an inductance element L ₁ , switching transistors Q ₁ and Q ₂ , an oscillation transformer OT, a resonance capacitor C, and resistors R _{1 to} R ₃ , and the oscillation transformer OT has a primary winding. N ₁ , a feedback winding N ₀ , a secondary winding N ₂ and preheating windings N ₃ , N ₄ are provided. Further, the output of the secondary winding N ₂ is applied to the discharge lamp FL via a current limiting element L ₂ for preventing high frequency noise composed of an inductance, and the current limiting element L ₂ is connected to the secondary winding N ₂ . The connection with the primary winding N ₁ is connected to the dense winding end side (winding start side). FIG. 12 shows a configuration example of the oscillation transformer OT, which is a date-shaped iron core X formed by a pair of E-shaped cores.
The coil bobbin Y around which the windings N _{0 to} N ₄ are wound is inserted and formed.

[Problems to be Solved by the Invention] However, in the above-described conventional example, the preheating winding N ₄ that is the second secondary winding of the oscillation transformer OT is not coupled to the primary winding N _1. Since it was wound on the winding start side of the dense secondary winding N ₂ , high-frequency noise generated from the discharge lamp FL and the switching transistor Q of the high-frequency oscillator circuit OSC.
High frequency noise generated by the switching operation of ₁ and Q ₂ is returned to the AC power supply AC side in a loop of the discharge lamp FL → preheating winding N ₄ → primary winding N ₁ without passing through the current limiting element L _2. Therefore, there is a problem that the noise level of the discharge lamp lighting device becomes high. In the figure, the imaginary line is the feedback loop of high frequency noise, C ₁ is the distributed capacitance between the iron core X and the primary winding N _1, and C ₂ is the distributed capacitance between the iron core X and the preheating winding N _4. , C
Reference numeral ₃ is a distributed capacity between the discharge lamp FL and the device P adjacent thereto.

Even when a lamp current detection winding similar to the preheating winding N ₄ of the above conventional example is provided as the second secondary winding of the oscillation transformer OT, the high frequency noise level is high due to the high frequency noise feedback. The problem occurs.

The present invention has been made in view of the above points, and its purpose is to eliminate high-frequency noise that returns to the AC power supply side in the loop of the discharge lamp, the second secondary winding, and the primary winding. An object of the present invention is to provide a discharge lamp lighting device that can be reduced in number and can reduce the high frequency noise level on the AC power supply side.

[Means for Solving the Problems] A discharge lamp lighting device according to the present invention includes a high frequency oscillation circuit having an oscillation transformer, a discharge lamp connected to a secondary winding of the oscillation transformer for high frequency lighting, and the discharge lamp. A second secondary connected to the oscillation transformer is provided with a current limiting element made of an inductance connected to the primary winding of the secondary winding and connected to a dense winding end side. A winding is provided, and the second secondary winding is wound around the winding end side where the primary winding of the secondary winding is loosely coupled.

[Operation] The present invention is configured as described above, and the second secondary winding wound around the oscillation transformer and coupled to the discharge lamp is loosely coupled to the primary winding of the secondary winding. Since it is wound on the winding end side, the high frequency noise returned to the AC power supply side in the loop of the discharge lamp → the second secondary winding → the primary winding can be reduced, and the high frequency noise level on the AC power supply side can be reduced. Can be reduced.

[Embodiment] FIGS. 1 and 2 show an embodiment of the present invention, which is connected to a high-frequency oscillator circuit OSC having an oscillating transformer OT and a secondary winding N ₂ of the oscillating transformer OT and is lit at a high frequency. And a discharge lamp FL connected to the discharge lamp FL.
The _second winding N ₂ is provided with a current limiting element L _{2 including} an inductance connected to the dense winding end of the secondary winding N _{2 and} the primary winding N _1, and is coupled to the discharge transformer FL in the oscillation transformer OT. the secondary winding is a preheating winding _N 3, the _{N 4} is provided, coupling the sparse winding end of the primary winding _{N 1} of the preheating winding _N 3, wherein the _{N 4} 2 winding _{N 2} It is wound on the side (winding end side).

The operation of the embodiment will be described below. Now, when a voltage obtained by full-wave rectifying the AC power supply AC by the diode bridge DB is applied to the high-frequency oscillator circuit OSC, the switching transistors Q ₁ and Q ₂ are connected to the bases via the resistors R ₁ , R ₂ , R ₁ and R _3. A current is supplied, one of the switching transistors Q ₁ and Q ₂ becomes conductive, and a collector current starts to flow. When this collector current begins to flow, a voltage is induced in each winding N _{0 to} N ₄ of the oscillation transformer OT, and the feedback winding N ₀ makes the switching transistors Q ₁ and Q ₂ in the conductive state non-conductive, and the non-conductive state. Feedback is applied in the direction of making the switching transistors Q ₁ and Q ₂ conductive, and the switching transistors Q ₁ and Q ₂ are alternately turned on and off. This oscillation frequency is about 30-50KH
The secondary winding N _{2 of the} oscillation transformer OT is set to z.
The discharge lamp FL is lit at a high frequency by the high frequency voltage induced in the discharge lamp FL. At this time, since the oscillating transformer OT is formed of a leakage transformer, the lamp current is limited by the leakage inductance.

By the way, the high frequency noise generated from the discharge lamp FL and the high frequency noise generated by the switching operation of the switching transistors Q ₁ and Q ₂ are fed back to the AC power supply AC side in a loop indicated by an imaginary line in the figure. Since the current limiting element L ₂ is present in the feedback loop, the high frequency noise fed back to the AC power supply AC side is suppressed, and the high frequency noise level can be reduced. Further, in the present invention, the second secondary windings, ie, the preheating windings N ₃ and N ₄ are wound around the winding end side of the secondary winding N ₂ and coupled with the primary winding N _1. Therefore, the high frequency noise returned to the AC power supply AC side in the loop of the discharge lamp FL → the preheating winding N ₄ → the primary winding N ₁ can be prevented, and the high frequency noise on the AC power supply AC side can be prevented. The level can be reduced.

FIGS. 3 and 4 show another embodiment. In a discharge lamp lighting device similar to the embodiment of FIG. 1, as shown in FIG. 4, the iron core X of the oscillating transformer OT has an E-shaped core. And the I-shaped core, and the primary winding N ₁ and the secondary winding N ₂ are overlapped and the preheating windings N ₃ and N ₄ are overlapped. In this case, the preheating winding _N 3, _{N 4} is located on the side end turns of the secondary winding _{N 2,} preheating winding _N 3, N
The coupling between the _fourth winding ₄ and the primary winding N ₁ becomes sparse, and the high frequency noise level on the AC power supply AC side is reduced as in the first embodiment. In addition, in the case of overlapping winding, the primary winding N ₁ and the secondary winding N ₂ are directly coupled to each other as compared with the case of split winding, and the coupling via the iron core X does not occur, so they are mutually coupled. The capacitance C ₁₂ can be reduced, and the noise reduction effect is further improved.

5 and 6 show still another embodiment,
The discharge lamp FL is adapted to be turned on, and the primary winding N ₁ and the secondary winding N ₂ of the oscillating transformer OT, which are overlapped with each other, are different from those of the embodiment of FIG. 4 as shown in FIG. Are in reverse order, the preheating windings N _{3 to} N ₅ are the secondary windings N 3.
_It is wound around the winding start side of _{No. 2 so} that the coupling with the primary winding N ₁ is loose. The operation is the same as in the above embodiment.

FIGS. 7 and 8 show still another embodiment,
L ₂ ′ and L ₃ ′ are current limiting elements composed of dimming inductances, and dimming switches S ₁ and S ₂ are connected in parallel, respectively. A lamp current detection winding N ₃ ′ is wound around the oscillation transformer OT as a second secondary winding. In the lamp current detection circuit DT, dimming is performed by the lamp current detection winding N ₃ ′ output. By detecting the state, the base currents of the switching transistors Q ₁ and Q ₂ are controlled (resistor ₁ is adjusted). Here, each winding N ₀ of the oscillation transformer OT
~ N ₂ and N ₃ ′ are wound as shown in FIG. 8, and the lamp current detection winding N ₃ ′ is wound on the winding end side of the secondary winding N _{2 and} the primary winding The connection with N ₁ is sparse.

Shows the FIG. 9 is yet another embodiment, three discharge lamp FL _"to high frequency lighting using this balancer L _2" balancer L ₂ a in which the current limiting element for high frequency noise rejection Yes, preheating windings N _{3 to} N wound around the oscillation transformer OT
₆ is wound on the winding end side of the secondary winding N ₂ so that the coupling with the primary winding N ₁ is loose.

The inductance originally required for the lighting circuit may be used as a current limiting element for suppressing high frequency noise, and when the inductance is provided on both sides of the secondary winding N ₂ ,
It suffices to connect an inductance having a large effect of suppressing high frequency noise to the winding end side where the secondary winding N _{2 and} the primary winding N ₁ are closely coupled.

[Advantages of the Invention] The present invention is configured as described above, and the second secondary winding wound around the oscillation transformer and coupled to the discharge lamp is coupled to the primary winding of the secondary winding. Since it is wound around the sparse winding end side, the high frequency noise returned to the AC power supply side in the loop of the discharge lamp → the second secondary winding → the primary winding can be reduced, and the high frequency on the AC power supply side can be reduced. There is an effect that the noise level can be reduced.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an embodiment of the present invention, FIG. 2 is a sectional view of an essential part of the same, FIG. 3 is a circuit diagram of another embodiment, FIG. 4 is a sectional view of an essential part of the same, and FIG. Is a circuit diagram of yet another embodiment, sixth
FIG. 7 is a sectional view of the essential part of the above, FIG. 7 is a circuit diagram of yet another embodiment, FIG. 8 is a sectional view of the essential part of the same, FIG. 9 is a circuit diagram of yet another embodiment, and FIG. 11 is a sectional view of the main part of the same as above.
FIG. 12 is a circuit diagram of a conventional example, and FIG. OSC is a high-frequency oscillator circuit, OT is an oscillation transformer, N ₀ ~
N ₆ is a winding wire, L ₂ , L ₂ ′, L ₃ ′ and L ₂ ″ are current limiting elements, and FL is a discharge lamp.

Claims (1)

[Scope of utility model registration request] 1. A high frequency oscillation circuit having an oscillation transformer,
From the inductance connected to the winding end side where the discharge lamp connected to the secondary winding of the oscillation transformer and lit at high frequency is connected to the discharge lamp and the primary winding of the secondary winding is densely connected. And a second secondary winding coupled to the discharge lamp is provided in the oscillation transformer.
2. The discharge lamp lighting device according to claim 1, wherein the secondary winding is wound around a winding end side where the primary winding of the secondary winding is loosely coupled.