JPS63193494A - Fluorescent lamp lighter - 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 Field of the Invention The present invention relates to a fluorescent lamp lighting device for lighting a fluorescent lamp at high frequency.

2. Description of the Related Art It is well known that by lighting a fluorescent lamp at high frequency, the lighting device can be made smaller and lighter, and the luminous efficiency can also be improved. A circuit generally used as a high-frequency lighting device is a single-stone exciter type inverter circuit shown in FIG.

In this circuit, when commercial power is turned on, rectifier 1
A power supply circuit including the smoothing capacitor 2 and the smoothing capacitor 2 serves as a DC power source, and current flows to the base of the transistor 9 through the resistor 14, turning the transistor 9 on. At that time, the collector current flows from the positive electrode of the smoothing capacitor 2 to the primary winding 4A of the oscillation transformer 4 to the emitter of the collector transistor 9 of the transistor 9 to the negative electrode of the smoothing capacitor 2.

Furthermore, since an electromotive force is generated in the secondary winding 4B of the oscillation transformer 4 in a direction that turns on the transistor 9, the transistor 9 maintains the on state. Next, transistor 9
The collector current 1c of I c <hfe-1b (h
When fe: current amplification factor, Ib: base current>, the collector current tends toward saturation, so the electromotive force of the secondary winding 4B turns off the transistor 9, and the transistor 9 rapidly turns off. Then, the electric charge that had been charged in the base current limiting capacitor 10 in the direction of making the base potential negative is discharged through the reset circuit consisting of the resistor 13 and the diode element 12 in series, and the base potential of the transistor 9 increases. (Then, it turns on again, and the same operation is repeated thereafter to perform high-frequency oscillation. As a result, a high-frequency voltage is generated in the primary winding 4A of the oscillation transformer 4, and the bidirectional semiconductor control element 8a breaks over, causing preheating. A current flows from the positive electrode of the smoothing capacitor 2 to the current limiting inductance element 6 → the electrode 5A of the fluorescent lamp 5 → the diode element 7 → the bidirectional semiconductor control element 8a → the electrode 5B of the fluorescent lamp 5 → the collector of the transistor 9.

When the high-frequency voltage of the oscillation transformer 4 is in the reverse cycle (when the transistor 9 is turned off), no preheating current flows due to the reverse voltage blocking effect of the diode element 7, and the high-frequency voltage is applied to the fluorescent lamp, resulting in half-wave preheating and half-wave preheating. By applying a wave voltage, the electrodes 5A and 5B of the fluorescent lamp are sufficiently preheated and started.

Problems to be Solved by the Invention However, in such a circuit, the bidirectional semiconductor control element 8a has variations in turn-off time tq, and if the turn-off time tq is long, the bidirectional semiconductor control element 8a
Since it is easy to turn on when it should be turned on and then turned off (the reverse voltage blocking effect of the diode element 7 does not work), the bidirectional semiconductor control element 8a operates in both directions. As a result, the element temperature of the bidirectional semiconductor control element 8a increases, and the breakover voltage further decreases.
Even when the fluorescent lamp shifts to main discharge, the bidirectional semiconductor control element 8a operates and the preheating current continues to flow. This causes problems such as abnormal heat generation in the bidirectional semiconductor control element 8a and a decrease in luminous flux of the fluorescent lamp.

Means for Solving the Problems The fluorescent lamp lighting device of the present invention is a fluorescent lamp lighting device using a high frequency transistor inverter circuit. It has a configuration in which a starting circuit is connected in series with a bidirectional semiconductor control element that is less than a second.

Turn-off time is 1.8 as a bidirectional semiconductor control device
By using a microsecond or less, even if the bidirectional semiconductor control element turns on and then turns on when it should turn off (the reverse voltage blocking effect of the diode element does not work), the time is short, so the bidirectional semiconductor control element cannot operate in both directions. As a result, when the fluorescent lamp shifts to main discharge, the lamp voltage drops and the bidirectional semiconductor control element becomes inoperable, and no preheating current flows.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings.

In FIG. 1, this circuit includes a rectifier 1 connected to a commercial power supply and a smoothing capacitor 2 connected to it to form a DC power supply section. A switching transistor 9 is connected in series to a parallel body of the resonant capacitor 3 and the primary winding 4A of the oscillation transformer 4. Further, a current limiting inductance element 6 and a fluorescent lamp 5 having a pair of electrodes 5A and 5B are connected in series, and a starting circuit consisting of a series body of a diode element 7 and a bidirectional semiconductor control element 8 is connected between the two electrodes. is connected. One end of the secondary winding 4B of the oscillation transformer 4 is connected to a base current limiting capacitor 10 and an inductor 1.
1 to the base of the transistor 9, and the other end is connected to the negative terminal of the DC power supply section. Further, a resistor 14 as a starting resistor of the transistor 9 is connected in series to a series body of a resistor 12 and a diode 13 as a reset circuit of the base current limiting capacitor 10.

Next, the operation of the above circuit will be explained.

When commercial power is turned on, a power supply circuit consisting of the rectifier 1 and the smoothing capacitor 2 creates a DC power supply, and current flows through the resistor 14 to the base of the transistor 9.
turns on. At that time, the collector current flows from the positive electrode of the smoothing capacitor 2 to the primary winding 4A-1 of the oscillation transformer 4, the collector of the transistor 9, the emitter of the transistor 9, and the negative electrode of the smoothing capacitor 2. Since an electromotive force is generated in the secondary winding 14B of the oscillation transformer 4 in the direction of turning on the transistor 9, the transistor 9 maintains the on state. Next, the collector current 1c of the transistor 9 is I
c < hfe ・Ib (hfe: current amplification factor, I
b: base current), since the collector current tends toward saturation, the electromotive force of the secondary winding 4B tends to turn off the transistor 9, and the transistor 9 quickly turns off. Then, the charge that had been charged in the direction of making the base potential of the base current limiting capacitor 10 negative is discharged through the reset circuit, and when the base potential rises again, the transistor 9 is turned on and the same operation is performed thereafter. Repeatedly performs high frequency oscillation. As a result, the oscillation transformer 4
A high frequency voltage having the waveform shown in FIG. 2 is generated in the primary winding 4A, the bidirectional semiconductor control element 8 breaks over, and the preheating current flows from the positive electrode of the smoothing capacitor 2 to the current limiting inductance element 6 to the electrode 5A of the fluorescent lamp. →Diode element 7
- Bidirectional semiconductor control element 8 → electrode 5B of fluorescent lamp 5
→Flows to the collector of transistor 9. When the high frequency voltage of the oscillation transformer 4 is in the reverse cycle (when the transistor 9 is turned off), no preheating current flows due to the reverse voltage blocking effect of the diode element 7, and the high frequency voltage is applied to the fluorescent lamp 5, resulting in half-wave preheating. Electrode 5A of fluorescent lamp 5 by applying a half-wave voltage.

Preheat the 5B sufficiently and start it. In the circuit of the embodiment of the present invention, since the turn-off time of the bidirectional semiconductor control element 8 is 1.8 μsec or less, the bidirectional semiconductor control element 8
It is easy to turn on when it should be turned on and then turned off (even if it is turned on (the reverse voltage blocking effect of diode element 7 does not work), but because the time is short, the bidirectional semiconductor control element is turned on in both directions. As a result, when the fluorescent lamp 5 shifts to main discharge, the lamp voltage decreases and
The bidirectional semiconductor control element 8 becomes inoperative, and no preheating current flows.

In this example circuit, the turn-off time tQ is 0.4 to 3.0μ
Lamp current 5 using bidirectional semiconductor control element
Turn on a fluorescent lamp of 60mA and lamp voltage of 55V,
An experiment was conducted to determine whether the preheating current could be cut off at startup.

The results are shown in FIG. In FIG. 3, the ◯ mark indicates the case where the bidirectional semiconductor control element is cut off, and the X mark indicates the case where the bidirectional semiconductor control element does not cut off.

It is clear from this figure that if the turn-off time tq is 1.8 μsec or less, the preheating current can be reliably turned off. As shown in FIG. 4, this turn-off time tq is determined by the breakover voltage of the bidirectional semiconductor control element of the lamp voltage (voltage waveform of the resonant capacitor) before transition to main discharge. f=42kHz, breakover pressure Vho=1
Assuming 10 V, the resonant voltage waveform in FIG. 4 reaches the breakover voltage Vbo=110 V at t=1.8 μsec.

As described in detail, according to the present invention, when starting a fluorescent lamp, the turn-off time tq of the starting circuit is 1.8.
By configuring the device in series with a bidirectional semiconductor control element that lasts less than microseconds and a diode element, the preheating current can be reliably cut off and transferred to the main discharge.As a result, abnormal heat generation of the bidirectional semiconductor control element and fluorescent lamp Decrease in luminous flux can be prevented.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram of a fluorescent lamp lighting device that is an embodiment of the present invention, Figure 2 is a voltage waveform diagram across a resonant capacitor in the same circuit, and Figure 3 is a diagram of the turn-off time of a bidirectional semiconductor control element. □Figure 4 is a diagram to explain the relationship between the voltage of the resonant capacitor and the breakover voltage of the bidirectional semiconductor control element, □Figure 5 is when the conventional fluorescent lamp is lit FIG. 3 is a circuit diagram of the device. 1... Rectifier, 2... Smoothing capacitor, 3... Resonant capacitor, 4... Oscillation transformer, 4A... Next winding , 4B...
・Secondary winding, 5...Fluorescent lamp, 5A, 5B・
... Electrode, 6 ... Current limiting inductance element, 7 ... Diode element, 8 ...
... Bidirectional semiconductor control element, 9 ... Transistor, 10 ... Base current limiting capacitor,
11... Inductor, 12... Diode, 13... Resistor, 14... Resistor. Taste So, 6 stone% - W Mi method

Claims (1)

[Claims] In a fluorescent lamp lighting device using a high frequency transistor inverter circuit, a fluorescent lamp having a pair of electrodes has a diode element and a turn-off time of 1.8μ between the electrodes.
1. A fluorescent lamp lighting device, characterized in that a starting circuit is connected in series with a bidirectional semiconductor control element that has a power consumption of less than 2 seconds.