JPH0246696A - Fluorescent lighting device - Google Patents

Abstract

PURPOSE:To prevent a high surge voltage from being applied between transistors, the collector thereof and the emitter thereof by connecting a capacitor between the base emitters of another transistor disposed in a drive circuit used for a dc fluorescent lamp. CONSTITUTION:A fluorescent lamp 41 is connected to the secondary coil 40 of a transformer 34 controlled on the basis of an output from an oscillating circuit 29. A capacitor 45 is connected between the base emitters of a transistor 42 disposed in a drive circuit connected to a preheating circuit 31. This can decrease the rising speed of transistors 43 and 44 used for the oscillating circuit 29, thereby reducing a surge voltage applied between the collector and the emitter of the two transistors 43 and 44 used for the oscillating circuit 29 at the time of lighting the fluorescent lamp.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention operates an oscillation circuit using a DC power supply, and lights a fluorescent lamp with the output of a transformer controlled by the output of the oscillation circuit. This invention relates to a fluorescent lamp lighting device that can adjust the brightness of the lamp.

2. Description of the Related Art Conventionally, this type of fluorescent lamp lighting device has a structure as shown in FIG. In FIG. 3, the emitter of a transistor 8 is connected to the input side of the DC power supply 1, a protective resistor 23 is connected between the base and the emitter of the transistor 80, and a drive circuit signal terminal 6 is connected from the base of the transistor 8 via the protective resistor 22. A choke 11 is connected between the input side of the dimmer circuit 4 and the DC power supply 10 and the primary winding 16 of the transformer 12 through the drive circuit 2 configured by connecting the Connecting the transistor 90 pace to the base winding end 18 of the transformer 12 from the collector of the transistor 8 through the resistor 26 to the base winding end 17 of the transistor 10 pace and the transformer 12, and the emitter of the transistor 9; The emitter of the transistor 1°, the anode of the diode 19, and the anode of the diode 20 are grounded, and the collector of the transistor 9, the primary winding end 14 of the transformer 12, and the diode 19 are grounded.
0 cathode is connected, the collector of transistor 10 is connected to the primary winding end 16 of transformer 12, and the cathode of diode 2o, and a capacitor 21 is connected between the collector of transistor 9 and the collector of transistor 1o. An oscillation circuit 3 is connected to the oscillation circuit 3, and a transformer 12 driven by the output of the oscillation circuit 3 is provided.
A fluorescent lamp 26 is connected to the secondary winding 13 of the fluorescent lamp 26.
The configuration was such that a preheating circuit 6 was connected to the.

Problems to be Solved by the Invention In such a conventional configuration, when the fluorescent lamp 26 is turned on, as shown in FIG. Due to the high surge voltage 7 applied, from the viewpoint of reliability as a fluorescent lamp lighting device, it is necessary to use transistors 9 and 1o that have a high breakdown voltage guarantee between the collector and emitter, which increases the cost. there were.

The present invention solves a complicated problem and aims to prevent high surge voltage from being applied between a transistor and its collector and emitter when a fluorescent lamp is turned on.

Means for Solving the Problem In order to solve this problem, the present invention connects a dimming circuit/oscillation circuit to the input side of a DC power supply via a drive circuit including a transistor, and controls the output of the oscillation circuit. A fluorescent lamp is connected to the secondary winding of the transformer, a preheating circuit is connected to the fluorescent lamp, and a capacitor is connected between the base and emitter of the transistor as the driving circuit. be.

Alternatively, a capacitor is connected between the base and emitter of the transistor of the driving circuit, and a resistor is connected between the emitter and the input of the transistor.

Effect This configuration allows the rise speed of the transistor used in the oscillation circuit to be slowed down, making it possible to lower the surge voltage that is applied between the collector and emitter of this transistor when the fluorescent lamp is turned on. It becomes a lighting device.

Embodiment FIGS. 1 and 2 are circuit diagrams of a fluorescent lamp lighting device according to an embodiment of the present invention. In FIG. 1, the emitter of a transistor 42 is connected to the input side of a DC power supply 27, and the base of the transistor 42 is A protective resistor 601 and a capacitor 45 are connected between the transistor 42 and the emitter, and the drive circuit signal terminal 32 is connected from the base of the transistor 42 through the protective resistor 49. A choke 33 is connected between the input side of the transistor 27 and the primary winding 36 of the transformer 34, and a choke 33 is connected from the collector of the transistor 42 to the base of the transistor 43 and the pace winding end 39 of the transformer 34 via a resistor 61. 4
2 is connected to the base of the transistor 44 and the base winding end 38 of the transformer 34 through the resistor 62, and the emitter of the transistor 43 and the transistor 4
The emitter of the transistor 43, the anode of the diode 47, and the anode of the diode 48 are grounded, and the collector of the transistor 43, the primary winding end 36 of the transformer 34, and the cathode of the diode 47 are connected. An oscillation circuit 29 configured by connecting the line end 37 and the cathode of a diode 48 and connecting a capacitor 46 between the collector of a transistor 43 and the collector of a transistor 44 is connected, and is driven by the output of this oscillation circuit 29. This is a fluorescent lamp lighting device in which a transformer 34 is provided, a fluorescent lamp 41 is connected to the secondary winding 40 of the transformer 34, and a preheating circuit 31 is connected to the fluorescent lamp 41 of ξ. In FIG. 2, a resistor 53 is connected between the input side of the DC power supply 27 and the emitter of the transistor 42 in the drive circuit 28.
A protective resistor 5 is connected between the base and emitter of the transistor 42.
0. This fluorescent lamp lighting device has a configuration in which a capacitor 46 is connected and a drive circuit signal terminal 32 is connected from the base of a transistor 42 via a protective resistor 49, and all other configurations are the same as in the previous section.

The basic operation of the drive circuit 28 in FIGS. 1 and 2 is as follows.
By grounding the drive circuit signal terminal 32, the transistor 42 is turned on, and the transistors 43 and 44 of the oscillation circuit 29 repeat 0N10FF.
A voltage is generated in the secondary winding 40 of No. 4 to turn on the fluorescent lamp 41.

Further, when the drive circuit signal terminal 32 is opened, the transistor 42 is turned off, and the oscillation circuit 29 is turned off.
The L fluorescent lamp 41 is turned off.・By connecting the capacitor 46 shown in FIG. 1, the capacitor 46 shown in FIG. Reduce the surge voltage applied between the emitters.

Effects of the Invention As described above, according to the present invention, the switching heat of the transistor used in the drive circuit is slowed down by a capacitor or a capacitor and a resistor, and the rise speed of the transistor used in the oscillation circuit is delayed. It is possible to lower the surge voltage applied between the collector and emitter of the two transistors used in the oscillation circuit when lighting a fluorescent lamp, and it can also be used with transistors with low breakdown voltage guarantee between the collector and emitter. This makes it possible to reduce the cost of a fluorescent lamp lighting device that can guarantee reliability. Although the embodiment of the present invention has been described using a circuit for one fluorescent lamp, it is of course applicable to a circuit for two lamps as well.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing a fluorescent lamp lighting device according to an embodiment of the present invention, Fig. 2 is a circuit diagram showing a fluorescent lamp lighting device according to another embodiment of the invention, and Fig. 3 is a circuit diagram showing a fluorescent lamp lighting device according to another embodiment of the present invention. FIG. 4, a circuit diagram showing the device, shows a surge voltage waveform applied between the collector and emitter of a transistor used in a conventional oscillation circuit. 27...DC power supply, 28...Drive circuit, 29...Oscillation circuit, 3o...Dimmer circuit, 31...Preheating circuit , 32...Drive circuit signal terminal, 33...Choke, 34...
...Transformer, 36.37...-Next winding end, 36...Transformer-Next winding, 38.39...
... Base winding end, 40 ... Transformer secondary winding, 41 ... Fluorescent lamp, 7 ... Surge voltage, 42 to 44 ... ...transistor, 47.
48...Diode, 45.46°...
Capacitor, 49.50... Protective resistor, 51,
52.53...Resistance.

Claims (2)

[Claims] (1) A dimming circuit/oscillation circuit is connected to the input side of the DC power supply via a drive circuit including a transistor, a transformer is provided that is controlled by the output of this oscillation circuit, and a fluorescent lamp is connected to the secondary winding of this transformer. A preheating circuit is connected to the fluorescent lamp, and a capacitor is connected between the base and emitter of a transistor of the driving circuit as the driving circuit. (2) The fluorescent lamp lighting device according to claim 1, wherein a capacitor is connected between the base and emitter of the transistor of the drive circuit, and a resistor is connected between the emitter and the input of the transistor.