JPS58137993A - Device for firing fluorescent lamp - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a lighting device for a fluorescent lamp used for night lighting indoors or outdoors.

Generally, this type of fluorescent lamp lighting device causes an oscillation transistor to oscillate when a switch is turned on, and this oscillation generates a high voltage on the secondary side of an oscillation transformer, and this high voltage lights the fluorescent lamp. For example,
In this lighting device, when the switch is turned on with the fluorescent tube removed, that is, with no load, a large current flows through the oscillation transistor, causing thermal runaway damage to the oscillation transistor. ,
This has the problem that battery power is wasted.

In view of the above problems, the present invention aims to prevent thermal runaway destruction of the oscillation transistor and wasteful consumption of battery power when the switch is turned on with the fluorescent tube removed, that is, with no load. This is the purpose.

The basic configuration of the present invention for achieving the above object is to connect the primary winding of the oscillation transformer and the filament preheating winding of the fluorescent tube on the secondary side of the oscillation transformer, and connect them to the battery power source. connected to the negative side and between the filament preheating winding and the filament of the fluorescent tube,
Connect a diode whose anode side is located on the negative side of the battery power source and whose cathode side is located on the filament side of the fluorescent tube, further connect the base of a no-load protection transistor to the cathode side of the diode, and connect its collector to the It is connected to the base circuit of the oscillation transistor.

With the above configuration, when the switch is turned on with the fluorescent tube removed, that is, with no load, the base current of the no-load protection transistor does not flow, so that the oscillation transistor also receives current. As a result, thermal runaway destruction of the oscillation transistor and wasteful consumption of the battery power source, which are conventional, can be prevented.

Hereinafter, one embodiment of the present invention will be described based on the drawings.

In the figure, 1 is the car battery power supply, DC12
It is a battery power source for V. 2 is an on-off switch connected to the positive side of the battery power source 1; 3 is an electrolytic capacitor connected in parallel to the battery power source 1; this electrolytic capacitor 3 is provided to reduce the internal impedance of the battery power source 1; It is something that was given. 4 is an oscillation transistor; 6 is a no-load protection transistor; this transistor 6 uses the base resistance 6 of the oscillation transistor 4 as a collector resistance. 7 is a resistor connected between the base and emitter of the no-load protection transistor 6; 8.9 is a capacitor connected in series with the base resistor 6 of the oscillation transistor 4; the connection point of this capacitor 8.9 is the oscillation transistor; It is connected to the emitter of 4. 10, 11, 12, 13.1
4 is a winding wound around the same ferrite core, and constitutes an oscillation transformer 16. And this oscillation transformer 16
The primary winding 11 of the oscillation transformer 16 is connected to the filament preheating winding [14] that preheats one filament 161L of the fluorescent tube 16 on the secondary side of the oscillation transformer 16, and these are connected to the negative side of the battery power source 1. ing. Further, the other filament 16b of the fluorescent tube 16 is connected to the filament preheating winding 12 on the secondary side of the oscillation transformer 16. 17 is a capacitor connected in parallel with the high voltage winding 13 on the secondary side of the oscillation transformer 15; 18 is a capacitor for controlling the fluorescent lamp current connected between one of the capacitors 17 and one of the filament preheating windings 12; It is a capacitor. 19 is the filament preheating winding 14 and the fluorescent tube 16;
The diode 19ij is connected between the filament 16 and one of the filaments 1, and the anode side of this diode 19ij is located at the negative terminal of the battery power supply 1, and the cathode side is located at the negative terminal of the battery power supply 1.
One filament of 6) is connected so as to be located on the 161L side. The base of the no-load protection transistor 5 is connected to the cathode side of the diode 19 via the resistor 2o, and the collector is connected to the base resistor 6 and the primary winding 1.
0 to the base of the oscillation transistor 4. Reference numeral 21 denotes a metal reflection plate, which is connected to the negative side of the battery power source 1 so as to serve as a nearby conductor.

The operation in the above configuration will be explained. First, when the fluorescent tube 16 is normally installed and the switch 2 is turned on, the pace current of the no-load protection transistor 6 passes through the resistor 20, one filament 16a1 of the fluorescent tube 16, and the filament preheating winding 14 to the battery. Since the current flows to the negative side of the power supply 1, the no-load protection transistor 6 is turned on.

When turned on, the oscillation transistor 4 is also turned on via the base resistor 6 to perform blocking oscillation, and this oscillation generates a high voltage on the secondary side of the oscillation transformer 16, which lights up the fluorescent tube 16.

On the other hand, when the switch 2 is turned on with the fluorescent tube 16 removed, that is, with no load, the pace current of the no-load protection transistor 6 causes the fragmentation of one filament (161L) of the fluorescent tube 16. Because it does not flow due to
The no-load protection transistor 5 is turned off. By turning off the oscillation transistor 4, the oscillation transistor 4 is cut off and no current flows, so that the oscillation transistor 4 is prevented from being destroyed by thermal runaway. Further, by cutting off the oscillation transistor 4, unnecessary consumption of the battery power source 1 can be prevented.

As described above, according to the present invention, when the switch is turned on with the fluorescent tube removed, that is, with no load, the structure is such that no current flows through the oscillation transistor, unlike in the conventional case. This prevents the oscillation transistor from being destroyed by thermal runaway, and also prevents wasteful consumption of the battery power source.

[Brief explanation of drawings]

The figure is a circuit diagram of a lighting device for a fluorescent lamp according to an embodiment of the present invention. 1...Battery power supply, 2...Switch, 4
...Oscillation transistor, 6...No-load protection transistor, 11...Primary winding, 1
4...Filament preheating winding, 16...
・Oscillation transformer, 16... Fluorescent tube, '16&...
...Filament, 19...Diode.

Claims (1)

[Claims] In a fluorescent lamp lighting device that causes an oscillation transistor to oscillate when a switch is turned on, and generates a high voltage on the secondary side of an oscillation transformer by this oscillation, and lights a fluorescent tube with this high voltage, the primary side of the oscillation transformer The winding is connected to the filament preheating winding of the fluorescent tube on the secondary side of the oscillation transformer, and these are connected to the negative side of the battery power supply, and a wire is connected between the filament preheating winding and the filament of the fluorescent tube. Connect a diode whose anode side is located on the negative side of the battery power source and whose cathode side is located on the filament side of the fluorescent tube, further connect the base of a no-load protection transistor to the cathode side of the diode, and connect its collector to the A fluorescent lamp lighting device connected in series to the base circuit of an oscillating transistor.