JPS62208594A - 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 ART It is well known that by lighting a fluorescent rung at high frequency, one lighting device can be made smaller and lighter, and the luminous efficiency can be improved. A -5 self-commutated inverter circuit shown in FIG. 3 is a circuit commonly used as a high-frequency lighting device. In this circuit, a rectifier IK smoothing capacitor 2 connected to a commercial power supply is connected to constitute a DC power supply section, and a resonance capacitor 3 and a switching transistor 8 are connected in series. Furthermore, one of the current limiting inductance elements 4
A starting circuit in which the next winding 4a and a fluorescent lamp 6 having a pair of electrodes 5&, sbl are connected in series, and a diode element 6 and a glow star tough for the fluorescent lamp are connected in series between both electrodes of the fluorescent lamp 5. are connected in parallel. Next, one end of the secondary winding 4b of the current limiting inductance element 40 is connected to the base of the transistor 8 via the base current limiting capacitor 9, and the other end is connected to the negative terminal of the DC power supply section. Further, a resistor 1o as a starting resistor is connected between the base and collector of the transistor 8, and a series body of a resistor 12 and a diode 11 is connected between the base current limit capacitor 9 as a reset/reset circuit between the base current and the emitter. ing.

Problems to be Solved by the Invention This circuit has the following problems when starting the fluorescent rung. In other words, 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 through the resistor 10 to the base of the transistor 8, turning the transistor 8 on. At that time, the collector current is the positive electrode of the smoothing capacitor 2 - the primary winding 4a of the current limiting inductance element - the electrode 51L of the fluorescent lamp 6 -> the diode element 6 - the glow starter 7 (the glow starter glows due to the voltage of the DC power supply). The discharge starts and the bimetal contacts and becomes conductive) - the emitter of the collector transistor 8 of the transistor 8 flows to the negative electrode of the flat Mt capacitor 2. Furthermore.

Since an electromotive force is generated in the secondary winding 4b of the current limiting inductance element 4 in the direction of turning on the transistor 8, the transistor 8 maintains the on state. Next, the collector current Ic of the transistor 8 is Ic>bte ・Is
(hfe: current amplification factor + base current), the collector current tends to saturation, so the secondary winding 4b
The electromotive force of will be in the opposite direction.

Therefore, transistor 8 is quickly turned off. At this time, due to the reverse voltage blocking action of the diode element 6, the energy accumulated in the primary winding 4a of the current limiting inductance element causes the primary winding 4& to carry -L (L: 1
A high voltage (inductance value) of the next winding 41L is generated, and cold cathode discharge starts before both electrodes 51L and 5b of the fluorescent lamp 1 are sufficiently preheated. As a result, the electrode 51L of the fluorescent lamp 6
, 5b, which causes problems such as early blackening and premature life due to scattering of the electron emitting material emitter.

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 rung connected via the current-limiting inductance element.
Connect the series body of the diode element and glow starter,
Furthermore, the present invention is characterized by a fluorescent lamp lighting device in which a positive temperature coefficient thermistor is connected in parallel with the diode element.

When the working transistor is in operation, the preheating current that flows through both electrodes of the fluorescent lamp flows from the positive electrode of the DC power supply section to the current limiting inductance element - one electrode - the diode element -> the glow starter, the other electrode - the negative electrode of the transistor DC power supply section. flows to. On the other hand, when the transistor is in operation, the energy accumulated in the current limiting inductance element is transferred to the current limiting inductance element, one electrode, and the positive temperature coefficient thermistor.

High voltage is not generated across the fluorescent lamp 6 because it is consumed in a closed circuit consisting of the glow starter and the other electrode. In this way, while preheating both electrodes of the fluorescent lamp, when the positive temperature coefficient thermistor reaches the switching temperature of the element due to self-heating, the resistance value becomes very large, and therefore the said closed circuit is formed. First, a high voltage is generated across the fluorescent lamp and the fluorescent lamp lights up.

Embodiment One embodiment of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, this fluorescent lamp lighting device has a rectifier 1 and a smoothing capacitor 2 connected to a commercial power source to form a DC power supply circuit. A resonance capacitor 3 and a switching transistor 8 are connected in series. Further, the primary winding 4a of the current limiting inductance element 4 and a fluorescent lamp 6 having a pair of electrodes 51L and 6b are connected in series, and a diode element 6 and a fluorescent lamp 6 are connected between the electrodes sa and sb of the fluorescent lamp 6. The series body with glow star tough is connected,
Furthermore, a positive temperature coefficient thermistor 13 is connected in parallel with the diode element 6. Next, 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, and the other end is connected to the negative terminal of the DC power supply circuit. Further, a diode 11 and a resistor 12 as a reset circuit for the base current limiting capacitor 9 are connected between the base and emitter of the transistor 8, and a resistor 1o as a starting resistor is connected between the base and collector.

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, and current flows to the base of the transistor 8 via the resistor 1o, turning the transistor 8 on.

At that time, the collector current of the transistor 8 is equal to
Next winding 41L - Electrode 6a of fluorescent lamp 6 - Diode element 6 - Glow starter 7 - Collector of transistor 8 Electrode 5 b of fluorescent lamp 6 - Collector-emitter of transistor 8 Flows to the negative pole of the smoothing capacitor.

Furthermore, the secondary winding 4 of the current limiting inductance element 4
b Ic ) Since an electromotive force is generated in the direction that turns on the transistor 8, the on state of the transistor 8 is maintained. At this time, both electrodes 5a of the fluorescent lamp 6.

A preheating current If1 shown in FIG. 2 (!L) flows through 6b.

Next, when the collector current IC>1lfe·I, the collector current is saturated and the electromotive force generated in the secondary winding 4b of the current limiting inductance element is reduced to the transistor 8.
The force 9 is in the OFF direction, and the transistor 8 is rapidly turned off. 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 closed circuit consisting of the positive temperature coefficient thermistor 13, glow star tough, and resonance capacitor 3. Therefore, no high voltage is generated across the fluorescent lamp 6, and a preheating current If2 shown in FIG. 2(b) flows through the electrodes 5N and 6b. Transistor 8 performs the above on/off operation.
By repeating, the alternating current preheating current 1t+ + I
rz (see FIG. 2(C)) flows, increasing the electrode temperature of the electrode 51.6b. Next, the positive temperature coefficient thermistor 13 has a low resistance value when it is cold, but when the element temperature rises due to Joule heat generated by the preheating current If2 and reaches the switching temperature, the resistance value increases rapidly, and the positive temperature coefficient thermistor 13 Since a closed circuit is not formed in the OFF state of the transistor 8 through the transistor 8, a high voltage due to the electromagnetic energy accumulated in the primary winding 4 of the current limiting inductance element 4 is applied to both ends of the fluorescent lamp 6, causing the fluorescent lamp 5 to emit light. Lamp 6 starts its main discharge. When the fluorescent lamp 6 is turned on, the voltage across the fluorescent lamp 6 decreases.

If the voltage is below the operating voltage of the Glow Star Tough, the starting circuit will not function. Therefore, since no current flows through the PTC thermistor 13, the element temperature decreases and the resistance value decreases.

Next, turn off the commercial power and repeat the same operation when turning it back on.

DETAILED DESCRIPTION OF THE INVENTION As described in detail, according to the present invention, since the time for which a sufficient preheating current is passed can be selected depending on the characteristics of the positive temperature coefficient thermistor, the flashing life of the fluorescent lamp can be greatly improved, and the flashing life of the fluorescent lamp can be greatly improved. When the light rung is on, the glow starter does not operate, so no preheating current flows, and there is no constant preheating loss.Furthermore, no current flows to the positive temperature coefficient thermistor, and the temperature of the positive temperature coefficient thermistor decreases, so that it will not start even when restarting. It can be started with the same operation as when the engine is running.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram of a fluorescent lamp lighting device which is an embodiment of the present invention, Figs. 2(a) to (C) are waveform diagrams of preheating current of the fluorescent lamp of the same device, and Fig. 3 is a conventional one. FIG. 2 is a circuit diagram of a fluorescent lamp lighting device of FIG. 1... Rectifier, 2... smoothing capacitor, 3...
・Capacitor for bending resonance, 4...Inductance element for bending current limiting, 6...Fluorescent lamp, 51L, sb・
・The song is pole, 6... Diode element, 7...
...Glow starter, 8...Transistor, 9
...Base current limiting capacitor, 10...
...Resistance, 11...Diode, 12...
...Resistance, 13...Positive characteristic thermistor.

Claims (1)

[Claims] A series body of a diode element and a glow starter 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 further the diode element A fluorescent lamp lighting device characterized in that a positive temperature coefficient thermistor is connected in parallel with the.