JPS62133699A - Fluorescent lamp burner - 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.

BACKGROUND OF THE INVENTION It is well known that by lighting a fluorescent lamp at a high frequency, the lighting device can be made smaller and lighter, and the luminous efficiency can be improved. A single-stone self-excited I/verter circuit shown in FIG. 4 is generally used as a high-frequency lighting device. In this circuit, a rectifier 1 and a smoothing capacitor 2 are connected to a commercial power source to form a power supply circuit, and a resonance capacitor 3 and a switching transistor 8 are connected in series.

Furthermore, the primary winding 4 of the current limiting inductance element 4
a and a fluorescent lamp 5 having a pair of electrodes 5a and sb are connected in series, and the starting circuit is composed of a series body of a diode 6 and a bidirectional semiconductor control element 7 between the electrodes 5a and Bb of the fluorescent lamp 5. is connected. One end of the secondary winding 4b of the current limiting inductance element 4 is connected to the base of the transistor 8 via the pace current limiting capacitor 9.
The other end is connected to the negative terminal of the power supply circuit, and a diode 11 and a resistor 12 as a reset circuit for the pace current limiting capacitor, and a resistor 10 as a starting resistor are connected to the base of the transistor 80.

Problems to be Solved by the Invention Problems encountered when starting a fluorescent lamp using the circuit shown in FIG. 4 will be described below. When commercial power is turned on, the smoothing capacitor 2 is charged through the rectifier 1, and current flows through the starting resistor 10 to the base of the transistor 8, turning the transistor 8 on. At that time, the collector current is as follows: positive electrode of the smoothing capacitor 2 → primary winding 4a of the current limiting inductance element 4 → electrode 6a of the fluorescent lamp → diode 6 → bidirectional semiconductor control element 7 → fluorescent lamp It flows from the electrode 6b to the collector emitter of the transistor 8 to the negative electrode of the smoothing capacitor 2. Further, since an electromotive force is generated in the secondary winding 4b of the current limiting inductance element 4 in a direction that turns on the transistor 8, the transistor 8 maintains the on state. Next, when the collector current of transistor 8 increases and becomes IC > hfo IB (IC: collector current, hfo: current amplification factor, more: pace current), the collector current approaches saturation, so the secondary winding The electromotive force of 4b is reversed, and transistor 8 is rapidly turned off. At this time, due to the reverse voltage blocking of the diode 6, the electromagnetic energy accumulated in the primary winding 4a of the current limiting inductance element 4 generates a high voltage of the primary winding value. Due to this high voltage, the fluorescent lamp 6 starts cold cathode discharge before the electrodes 5a and 6b are sufficiently preheated.

As a result, problems arise such as early blackening of the inner surface of the glass tube due to scattering of the electron radioactive material of the electrodes 6a and 5b of the fluorescent lamp 5, and a shortened service life.

Means for Solving the Problems The present invention provides a transistor inverter circuit having a current-limiting inductance element between a pair of electrodes of a fluorescent lamp connected through the current-limiting inductance element.
A fluorescent lamp lighting device is characterized in that a series body of a diode and a bidirectional semiconductor control element is connected, and a surge voltage absorbing element is connected in parallel with the series body of the diode and the bidirectional semiconductor control element. It is something.

Operation First, during transistor operation of the transistor inverter circuit, the preheating current of the fluorescent lamp flows through the series body of the diode and the bidirectional semiconductor control element. Next, during transistor operation, the electromagnetic energy stored in the current limiting inductance element is absorbed by the surge voltage absorbing element, so the voltage applied across the fluorescent lamp becomes the clip voltage of the element. If this clip voltage is set below the cold cathode discharge starting voltage of the fluorescent lamp, the main discharge of the fluorescent lamp will not start. By repeating this series of on-off operations of the transistor, a half-wave current flows through the electrodes, and when the electrodes are sufficiently preheated, the fluorescent lamp starts its main discharge due to the clip voltage applied to both ends of the fluorescent lamp. .

Embodiment First, the basic configuration of a circuit according to an embodiment of the present invention will be explained with reference to FIG.

As shown in FIG. 1, a series body of a resonance capacitor 3 and a switch S is connected between the positive terminal and the negative terminal of the power supply circuit.
Resonant capacitor 3 and current limiting inductance element 4
A fluorescent lamp 6 having a pair of electrodes 5a and 5b is connected to an inverter circuit having a current limiting inductance element 4. and the electrode 6a of the fluorescent lamp 6.

A series body of a diode e and a bidirectional semiconductor control element 7 is connected between 5b, and a surge voltage absorbing element 1 is connected in parallel with the series body of a diode 6 and a bidirectional semiconductor control element 7.
3 is connected.

In such a circuit, when the switch S is in the on state,
Positive terminal → primary winding 4 of current limiting inductance element 4
a → electrode 6a → diode 6 → electrode 5b → bidirectional semiconductor control element 7 (the positive terminal voltage is higher than the breakover voltage of the bidirectional semiconductor control element) → electrode 5b → switch S → negative terminal closed circuit A preheating current If flows. Next, when the switch S is turned off, the electromagnetic energy accumulated in the primary winding 4a of the current limiting inductance element 40 is
The voltage absorbed by the surge voltage absorbing element 13 and applied to both ends of the fluorescent lamp 6 becomes the clip voltage vZ of the surge voltage absorbing element 13. At this point, since the clip voltage vZ of the surge voltage absorbing element 13 is set below the cold cathode discharge starting voltage of the fluorescent lamp 6, the main discharge does not start. Half-wave preheating is performed by repeating this series of turning the switch S on and off, and when the electrodes 5a and 5b are sufficiently preheated, the clip voltage Vz across the fluorescent lamp 60 increases.
As a result, the fluorescent lamp 5 starts its main discharge.

Next, one embodiment of the present invention will be described using the drawings.

In this circuit, a rectifier 1 and a smoothing capacitor 2 are connected to the commercial power supply.
are connected to form a power supply circuit. A resonance capacitor 3 and a switching transistor 8 are connected in series. In addition, 1 of the current limiting inductance element 4
The next winding 4a and a fluorescent lamp 6 having a pair of electrodes 6a and 5b are connected in series, and the electrodes sa and 6b of the fluorescent lamp 5 are connected in series.
A starting circuit in which a surge voltage absorbing element 13 is connected in parallel with a series body of a diode 6 and a bidirectional semiconductor control element 7 is connected between them. Furthermore, one end of the secondary winding 4b of the current limiting inductance element 4 is connected to the base of the transistor 8 via the base current limiting capacitor 9,
The other end is connected to the negative terminal of the power supply circuit. In addition, a diode 11. is used as a reset circuit for the base current limiting capacitor 9. A resistor 10 is connected to the base of the transistor 8, with a resistor 12 serving as a starting resistor.

Next, the operation of this circuit will be explained. When commercial power is turned on, the smoothing capacitor 2 is charged via the rectifier 1, current flows to the base of the transistor 8 via the starting resistor 10, and the transistor 8 is turned on. At that time, the collector current of the transistor 8 is as follows: positive electrode of the smoothing capacitor 2 → primary winding 4a of the current limiting inductance element 4 → electrode 6a of the fluorescent lamp 6 → diode 6 → bidirectional semiconductor control element 7 → Flows from the collector emitter of transistor 8 to the negative electrode of the smoothing capacitor. Since an electromotive force is generated in the secondary winding 4b of the current limiting inductance element 4 in a direction that turns on the transistor 8, the on state of the transistor 8 is maintained. At this time, the electrodes sa, 6b
The zero-order collector current increases through which the half-wave preheating current If (waveform shown in Figure 3) flows, and IC>hfo・IB(
IC: collector current, 1B two base current, hf,:
current amplification factor), the collector current saturates, so the electromotive force generated in the secondary winding 4b of the current limiting inductance element 4 moves in the direction of cutting off the transistor 8, and the transistor 8 quickly turns off. Become.

When the transistor 8 is turned off, the electromagnetic energy accumulated in the primary winding 4a of the current limiting inductance element 4 is absorbed by the surge voltage absorbing element 13, and the clip voltage vZ of the surge voltage absorbing element increases when the fluorescent lamp 6 is applied to both ends of . Here, since the clipping voltage vZ is set below the cold cathode discharge starting voltage of the fluorescent lamp 6, the main discharge does not start. By repeating this series of on-off operations, half-wave preheating is performed, and the electrode 5a is heated.

5b is sufficiently preheated, the fluorescent lamp 6 starts its main discharge by the clip voltage Vz applied across the fluorescent lamp 60. When the fluorescent lamp 6 is turned on, the voltage across the fluorescent lamp 6 decreases to below the breakover voltage of the bidirectional semiconductor control element 7, and the starting circuit does not operate.
Preheating current f does not flow.

Effects of the Invention As described above, the present invention provides a structure in which a fluorescent lamp is connected between a pair of electrodes.
By connecting a series body of a diode and a bidirectional semiconductor control element, and further connecting a surge voltage absorbing element in parallel with this series body, the high voltage applied to the fluorescent lamp can be absorbed by the surge voltage absorbing element. Therefore, it is possible to provide a fluorescent lamp lighting device that can prevent cold cathode discharge and therefore significantly extend the flashing life of the fluorescent lamp.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram showing the basic configuration of a fluorescent lamp lighting device of the present invention, Fig. 2 is a circuit diagram of a fluorescent lamp lighting device which is an embodiment of the present invention, and Fig. 3 is a circuit diagram of the fluorescent lamp lighting device according to an embodiment of the present invention. A waveform diagram of the preheating current in the lighting device, FIG. 4 is a circuit diagram of a conventional fluorescent lamp lighting device. 1... Rectifier, 2... Smoothing capacitor, 3... Resonant capacitor, 4... Current limiting inductance element, 4a...1 Secondary winding, 4b... Secondary winding, 6... Fluorescent lamp, 5a, 5b... Electrode, 6... Diode, 7... ...Bidirectional semiconductor control element, 8.
...Transistor, 9...Base current limiting capacitor, 1o...Starting resistor, 11...
...Diode, 12...Resistor, 13...
...Surge voltage absorption element. Name of agent: Patent attorney Toshio Nakao and one other person
-electrode 5b-electrode

Claims (1)

[Claims] A series body of a diode and a bidirectional semiconductor control element is connected between a pair of electrodes of a fluorescent lamp connected to a transistor inverter circuit having a current-limiting inductance element via the current-limiting inductance element, and A fluorescent lamp lighting device characterized in that a surge voltage absorbing element is connected in parallel with the series body of the diode and the bidirectional semiconductor control element.