KR0151539B1 - Electronic starter for fluorescent lamp - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a starter in a lighting device of a fluorescent lamp comprising a magnetic coil ballast and a starter. The field effect transistor (FET, IGBT) 6 is provided at the output of the rectifier circuit, and the fluorescent lamp is turned on when the lighting switch is turned on. After preheating, the preheating time is gradually adjusted by turning on the fluorescent lamp by the ballast 2 while the field effect transistor 6 is cut off by the gate power cut-off circuit when sufficient preheating is performed. By increasing the pressure, the impact does not occur during the preheating of the filament, so that the hot electron emission life of the filament is not shortened, and the light is switched at the moment when the potential of the AC power source reaches the highest peak point. It is possible to make a single lighting by generating maximum strike voltage when switching. To provide an electronic starter for fluorescent lamps.

Description

Electronic Starter for Fluorescent Lamps

1 is an overall circuit diagram of the present invention.

2 is an operating characteristic diagram according to an embodiment of the present invention,

(a) is a voltage characteristic diagram at both ends of filament.

(b) is a rectified voltage characteristic diagram.

(c) is a voltage characteristic of a striking time capacitor.

* Explanation of symbols for main parts of the drawings

2: ballast 5: rectifier circuit

6: field effect transistor (F.E.T IGBT) 8: zener diode

10: S.C.R. 11: condenser

12,16: Thermistor 161: heat conduction plate

The present invention relates to a starter in a lighting device of a fluorescent lamp consisting of a magnetic coil type ballast and a starter, in particular to preheat the filament when the fluorescent lamp is turned on, and to adjust the preheating time according to the ambient temperature, and gradually increase the preheating current. This prevents the impact from occurring during the preheating of the filament, thereby reducing the hot electron emission life of the filament, and performs light switching at the moment when the potential of the AC power source reaches the highest peak point. It is to provide an electronic starter of a fluorescent lamp that is capable of generating a single light by switching the maximum light voltage during switching.

MEANS TO SOLVE THE PROBLEM In the development of the electronic starter for fluorescent lamps, US inventors No. 4,513,227, 4,749,909, Japan Patent Publication 52-4672, 52-18078, 52-19481, 54-0584, and the United Kingdom. Patent 159225 and related technologies have been reviewed and their problems have been studied. It has been found that the main technical gist or constructional feature of the above prior arts is to obtain a lighting signal by C.R resonance or time constant time circuit and to use transistor, S.C.R or triac as switching power element.

However, the conventional techniques as described above, there is a control means for generating a strike voltage at the peak point of the alternating voltage flowing through the filament of the fluorescent lamp, the phase of the alternating voltage There is a drawback that lighting switching is always performed at a phase other than the peak point, and it is not possible to expect a single lighting at all times, and it is difficult to secure proper preheating time according to the voltage fluctuations and the ambient temperature environment. It was found that there is a defect that blackening phenomenon occurs.

In addition, conventional starters using transistors or SCRs are generally half-wave rectified, so lighting is unstable, and triac is inconsistent bidirectional rectification and electrical characteristics inherent to semiconductors. Found to be prone. Moreover, starters using these semiconductors tend to reduce the strike voltage of the lighting circuit because the switching time is long and the gate or base is a current-type ON-OFF method and the switching impedance is low.

Due to the above characteristics, the conventional starter circuits and devices described above have a narrower adaptation range than the metal contact type starters due to the ambient temperature and voltage fluctuation characteristics, and thus cannot be used in fluorescent lamps of various standards and are not suitable for specific specifications and characteristics. The following limited use was inevitable, and there was a deficiency in the lack of safety devices or control measures in case of overheating of the starter due to abnormal circuits.

Therefore, the present invention enables the lighting switch to be performed at a time when the fluorescent lamp is turned on at the moment when the power source of the AC power reaches the highest peak point in the lighting process by the minimum circuit configuration so that the single lamp can be turned on at all times, thereby improving the life of the fluorescent lamp. It is to provide a technology that can be extended as much as possible, and the automatic adjustment of the preheating time for ambient temperature and voltage fluctuations. In particular, the present invention uses a power semiconductor device, such as a field effect transistor (FET or IGBT) as a switching device, thereby increasing the switching circuit impedance to increase the efficiency of generating a strike voltage, the both ends (A, K or C, By using the high-resistance conduction characteristic of E), the gate driving voltage can be obtained even while the device is conducting and the filament is preheated, and the fluorescent lamp is always provided by providing a lighting timing function that induces an induced voltage at the maximum peak of the AC phase. It is to provide a single point of light and to provide a means to protect the starter overheating. Referring to the present invention as described above is as follows.

As shown in FIG. 1, one end of each filament 3,31 of a fluorescent lamp is connected to the AC power input via a magnet coil stabilizer 2, and a starter is connected to the other end of each filament 3,31. The field effect transistor (FET, IGBT) 6, which is a switching element provided at the output of the rectifier circuit, the gate power supply circuit of the field effect transistor 6, the gate power cut-off circuit, and an overheat protection device. The starter is configured, and the gate power supply circuit of the field effect transistor 6 is composed of a resistor 7, a zener diode 8, and a capacitor 9, and the gate power supply disconnection circuit is formed of a gate and a cathode of the field effect transistor 6. The SCR 10 is provided between the terminals and the trigger circuit of the SCR 10 provided at its gate. The trigger circuit of the SCR 10 is composed of a resistor 13, a thermistor 12, a capacitor 11, A timing (time constant) circuit composed of a resistor 14, The thermal protection device is a thermistor (16) installed between the gate and the negative terminal (-) of the total effect transistor (6) and the heat conduction plate (161) provided between the field effect transistor (6) and thermistor (16). Configure.

That is, as shown in FIG. 1, the both ends 3 and 31 of the fluorescent lamp filament are connected to the AC input of the rectifying circuit 5, and the field effect transistor (P, P) is connected in parallel with the rectifying output (+,-) of the rectifying circuit 5. 6) Connect (F, E, T or IGBT), connect the collector of this device to the plus side and the emitter to the minus side. A resistor 7 is provided between the collector and the gate of the field effect transistor 6, and a zener diode 8 and a smoothing capacitor 9 are provided in parallel between the gate and the emitter.

The thermistor 16 is connected in parallel to the smoothing condenser 9 or the zener diode 8 and the SCR 10 is connected in parallel thereto, and the anode side of the SCR 10 is connected to the field effect transistor 6. Connect the gate and connect the cathode side to the negative side of DC power. The gate of the SCR 10 is connected to one side of the thermistor 12, the other side of the thermistor 12 is connected in series with the resistor 13, and the timing capacitor 11 and the resistor between the gate and the cathode of the SCR. Connect (14) in parallel.

Such a preheating function of the present invention will be described with reference to FIG. When power is applied to the AC alternating current input (1), power is supplied to the rectifier circuit (5) through the ballast (2) and the filament (3), and the positive pulse current voltage rectified by the rectifier circuit (5) is the resistance (7). It is applied to the gate of the field effect transistor (6) through. At this time, the voltage applied to the gate of the field effect transistor 6 is determined by the zener diode 8, and is actually determined at about 10-15V. The voltage applied to the gate of the field effect transistor 6 is a rectified circuit (5) because the DC voltage smoothed by the pulsation or smoothing capacitor (9) is made, and the field effect transistor (6) is conducted by the smoothed voltage. The positive power supply of is a closed circuit connected to the negative, and thus the fluorescent lamp is preheated to the filament 3 of the fluorescent lamp during the preheating time Hf represented by (a) of FIG. At this time, since a high semiconductor junction resistance of about 1.5Ω to 2.5Ω is generated between the collector and the emitter of the field effect transistor 6, the resistor 13, thermistor 12, and the capacitor 11 consist of a resistor 14 Even when the gate power supply disconnecting circuit is connected in parallel to the collector and the emitter, the gate applied voltage capable of conducting the field effect transistor 6 by the resistor 7 and the zener diode 8 is maintained and thus the preheating period Hf. You can keep the conduction state for a while.

While a voltage is applied to the gate of the field effect transistor 6 and the field effect transistor 6 is conducting, a pulse flow such as (b) of FIG. 2 is transmitted through the resistor 13 and the thermistor 12. Flows). While the timing capacitor 11 is charged for a predetermined time determined by the resistance value of the resistor 13 and thermistor 12 and the time constant of the timing capacitor 11, the output of the timing capacitor 11 has a discharge resistor 14 The charging voltage containing the pulsating ripple as shown in FIG. When the charging voltage reaches a constant voltage Tv capable of triggering the SCR 10, the S and the CR 10 become conductive and discharge all of the positive charge applied to the gate of the field effect transistor 6. Therefore, the field effect transistor 6 is cut off, and thus, as shown in FIG. 2A, the lighting voltage Vst is generated at the anode of the fluorescent lamp filament, and the fluorescent lamp is turned on by the voltage. As shown in Fig. 2, the tube current 4 flows through the fluorescent lamp and the filament anode voltage falls below 1/2.

When the lighting voltage Vst occurs, the timing of reaching the trigger voltage Tv of the timing capacitor 11 is always synchronized with the peak point of the AC power supply, so that the most powerful and effective magnetic induction voltage can be induced from the ballast 2. It is. This allows a single light after sufficient preheating.

On the other hand, once the S.C.R 10 is triggered and conducting, the field effect transistor 6 remains in a blocking state because the DC current is maintained as long as the DC current is maintained. The preheating time of the fluorescent lamp varies slightly depending on the type of lamp, but usually takes 0.8 to 2.4 seconds at room temperature (25 degrees Celsius) when the rated voltage is applied. When designed for a lamp of a certain standard, the starter of the present invention is based on the optimum preheating time at room temperature and rated voltage, and the resistance value of the thermistor 12 is because the thermistor has a negative resistance when the ambient temperature decreases. The higher the time, the longer the charge time constant of the timing capacitor 11, the longer the preheating time and the higher the temperature, the lower the resistance value of the thermistor 12, the shorter the charge time constant and the shorter the preheating time. This serves to compensate for the filament heat cathode electron emission of the fluorescent lamp over temperature, providing a very ideal lighting condition. In addition, if the voltage is high, the current of the filament (3) also increases, so the preheating time may be shortened. If the voltage is low, the preheating time should be increased. However, if the voltage is high, the time to be discharged to the timing capacitor 11 is shortened and the preheating time is shortened. If it is low, the time to charge the timing capacitor 11 becomes long, and the preheating time becomes long. The thermistor 16 has a negative resistance characteristic (NTC) and maintains a high resistance up to a certain temperature above room temperature, but when the field effect transistor 6 generates heat and overheats to about 60 ° C. or more, the thermal conductor 161 is opened. When heat is transmitted to the thermistor 16, the resistance value of the thermistor 16 is rapidly lowered, which cuts off the field effect transistor 6 so that no current flows through the field effect transistor 6 any more. Therefore, the field effect transistor is controlled so that no overcurrent flows or only a very weak current flows. This function is more effective than the conventional technology in which a fuse is built so that the circuit can be broken when overheated. Therefore, the function of the electronic starter is more effective when the cause of the abnormality in the lighting circuit is eliminated. It is possible to restore normal function automatically, thereby increasing economic and reliability.

As described above, the present invention has a function of automatically adjusting the ideal preheating time with respect to temperature and voltage fluctuations. The ON-OFF switching element is constituted by the field effect transistor 6 and the gate is formed of the zener diode 8 and the capacitor 9. Trigger on preheating time setting timing condenser 11 to flow the onion rectified bridge rectified by the rectifier circuit 5 so that the AC firing phase as shown in FIG. This is to provide possible functionality. If there is no such function, it may be fired at the zero cross point of the alternating current applied to the filament 3, in which case the first point is impossible.

As described above, the present invention provides a technique for exerting the most ideal function for lighting a fluorescent lamp by harmonizing the characteristics of several components composed mainly of the characteristics and functions of the field effect transistor as described above, and can provide a contactless electronic starter. .

Claims (4)

The field effect transistor (FET, IGBT) 6 installed at the output of the rectifier circuit, the gate power circuit of the field effect transistor 6, a gate power cut-off circuit and an overheat protection device. Starter. The electronic starter for a fluorescent lamp according to claim 1, wherein the gate power supply circuit is composed of a resistor (7), a zener diode (8), and a capacitor (9). 3. The gate power cut-off circuit according to claim 1 or 2, comprising a SCR (10) provided between the gate and the cathode terminal of the field effect transistor (6) and a trigger circuit of the SCR (10) provided in the gate, The trigger circuit of the SCR (10) is composed of a timing (time constant) circuit composed of a resistor (13), a thermistor (12), a capacitor (11), and a resistor (14). The overheat protection device according to claim 1 or 2, wherein the overheat protection device comprises a thermistor (16) provided between the gate of the field effect transistor (6) and the cathode terminal (-), the field effect transistor (6) and the thermistor ( 16) An electronic starter for fluorescent lamps, comprising a heat conduction plate 161 provided between them.