JPH03252092A - Fluorescent lamp lighting device - Google Patents

Abstract

PURPOSE:To start a fluorescent lamp with an inexpensive circuit structure by connecting a Zener diode between the base terminal of a transistor and a diode. CONSTITUTION:A closed circuit is formed of a AC power source 1, a stabilizer 2 and a fluorescent lamp 3, a noise preventing capacitor 4 is connected to both the end of the fluorescent lamp 3, and the collector terminal and emitter terminal of a transistor 13 having a base circuit for conducting switching by a timer circuit formed of a resistance 6 and an electrolytic capacitor 8 are connected between non-power source side preheating electrode terminals of the fluorescent lamp 3 through a diode 5. Further, a Zener diode 12 is connected between the base terminal of the transistor 13 and the diode 5. As the voltage of the timer circuit is held at the Zener voltage, timer function is satisfied. Consequently, the electrode of the fluorescent lamp can be preheated by the preheating current of only the single wave cycle of the power source voltage. Hence, the fluorescent lamp can be started with an inexpensive circuit structure.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a fluorescent lamp starting device, and more particularly to a starting device using a semiconductor switching element for a fluorescent lamp having a preheating electrode.

A glow starter has been mainly used as a starting device for conventional fluorescent lamps, but this has drawbacks such as a long starting time and a short lifespan. Recently, starting circuits using semiconductor switching elements have been developed, but their demand has been limited due to their high cost. For this reason, there is a demand for the development of an inexpensive circuit type starting device using a semiconductor switch element.

Based on the above requirements, a circuit as shown in FIG. 3 using an inexpensive transistor as a semiconductor switching element has been proposed. In the figure, 1 is an AC power supply, 2 is a ballast, and 3
is a fluorescent lamp, 4 is a noise prevention capacitor, 5 is a diode, 6, 7, 11゜15 is a resistor, 8 is an electrolytic capacitor,
9 is a Zener diode, 10 is a thyristor, 12 is a Zener diode, 13 is a transistor, and 14 is a bidirectional semiconductor control element.

Next, the operation of this circuit will be explained with reference to the voltage and current waveforms of each part shown in FIG. In the figure, ■ is the waveform of the power supply voltage, ■ is the waveform of the ballast 2. Waveform of preheating current of fluorescent lamp 3,
vtp is the voltage waveform across the fluorescent lamp. Here, when the power supply voltage (2) is in a negative cycle, the bidirectional semiconductor control element 14 breaks down at a time point of 1°, and a preheating current flows through the diode 5 to the fluorescent lamp 3. The preheating current is cut off at time t2 when the holding current of the bidirectional semiconductor control element 14 becomes lower than that. Next, when the power supply voltage V is in a positive cycle, when the bidirectional semiconductor control element 14 breaks down again at time t3, the base current is supplied to the base of the transistor 13 via the resistor 11, so that the resistor A collector current flows into the transistor 13 via the transistor 15 . By connecting this resistor 15, even when the transistor 13 is on, the power source of the timer circuit of the resistor 6 and the electrolytic capacitor 8 is maintained at the power supply voltage. In this way, the preheating current flows in both waves to preheat the preheating electrode of the fluorescent lamp 3, and at a certain time, the timer circuit transfers the charge of the electrolytic capacitor 8 to the gate terminal of the thyristor 10 through the resistor 7 and the Zener diode 9. released, thyristor 10
Turn on. If that time point is t4, transistor 1
Since the collector current of No. 3 is forcibly turned off, a kick voltage vtp is generated due to the inductance of the ballast 2, and the fluorescent lamp 3 can be turned on.

Problems to be Solved by the Invention In the starting circuit using the transistor 13 as a semiconductor switching element, the resistor 15 is used so that the timer circuit functions even when the transistor 13 is turned on. During the cycle, the current is limited by the resistor 15, resulting in insufficient preheating current. for that,
In such a circuit, half-wave preheating is required during the negative cycle of the power supply voltage, and in order to prevent the preheating operation after lighting, it is necessary to use an expensive bidirectional semiconductor control element, which limits cost reduction. There is.

Means for Solving the Problems The fluorescent lamp lighting device of the present invention constitutes a closed circuit with an AC power supply, a ballast, and a fluorescent lamp with a preheating electrode, and a timer circuit is connected between the preheating electrode terminals on the non-power side of the fluorescent lamp. Connect the collector and emitter terminals of a transistor with a base circuit that performs switching via a diode,
A Zener diode is connected between the base terminal of the transistor and the diode.

Even when the active transistor is turned on, the voltage of the timer circuit is maintained at the Zener voltage by connecting the Zener diode between the base terminal of the transistor and the diode, so that the timer function can be satisfied. As a result, the electrodes of the fluorescent lamp can be sufficiently preheated with a preheating current of only one cycle of the power supply voltage.

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

In Figure 1, an AC power supply 1, a ballast 2, and a fluorescent lamp 3
A closed circuit is constructed. A noise prevention capacitor 4 is connected to both ends of the fluorescent lamp 3. A collector terminal and an emitter terminal of a transistor 13 having a base circuit that performs switching by a timer circuit consisting of a resistor 6 and an electrolytic capacitor 8 are connected between the non-power supply side preheating electrode terminals of the fluorescent lamp 3 via a diode 5. connected. Furthermore, a Zener diode 12 is connected between the base terminal of the transistor 13 and the diode 5.

In addition, in Fig. 1, 7 is a resistor, 9 is a Zener diode,
10 represents a thyristor, and 11 represents a resistor.

Next, the operation of this circuit will be explained with reference to the voltage and current waveforms of each part shown in FIG. In the figure, ■ is the waveform of the power supply voltage, ■ is the waveform of the preheating current of the ballast 2 and the fluorescent lamp 3, and vtp is the voltage waveform across the fluorescent lamp. Here, when the power supply voltage V is in a negative cycle, no preheating current flows through the fluorescent lamp 3 due to the reverse blocking characteristic of the diode 5.

Next, when the power supply voltage V is in a positive cycle, when the power supply voltage V becomes equal to or higher than the voltage of the Zener diode 12 at time t, the base current is supplied to the base of the transistor 13 via the resistor 11. A collector current flows from the AC power supply 1 to the transistor 13 via the diode 5. At this time, the power source of the timer circuit including the resistor 6 and the electrolytic capacitor 8 is maintained at the Zener voltage of the Zener diode 12. In this way, the preheating current flows in a half wave, and the fluorescent lamp 3
The preheating electrode is preheated, and when the time set by the timer circuit is reached, the charge of the electrolytic capacitor 8 is released to the gate terminal of the thyristor 10 through the resistor 7 and the Zener diode 9, and the thyristor 10 is activated. Turn on. Assuming that time point is t2, since the collector current of the transistor 13 is forcibly turned off, a kick voltage vtp is generated due to the inductance of the ballast 2, and the fluorescent lamp 3 is turned on.

As described in detail, the present invention can provide a fluorescent lamp lighting device that can start a fluorescent lamp with an inexpensive circuit configuration without using expensive elements such as bidirectional semiconductor control elements. be.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram of a fluorescent lamp lighting device which is an embodiment of the present invention, Fig. 2 is a voltage and current waveform diagram of the same circuit, Fig. 3 is a circuit diagram of a conventional fluorescent lamp lighting device, and Fig. 4 is a circuit diagram of a fluorescent lamp lighting device according to an embodiment of the present invention. FIG. 3 is a voltage and current waveform diagram of a conventional device. 1... AC power supply, 2... Ballast, 3.
...Fluorescent lamp, 5 ...Diode, 6
．． 7...Resistance, 8...1! Solution capacitor, 9... Zener diode, 10...
... Thyristor, 12 ... Zener diode, 13 ... Transistor, 14 ... Bidirectional semiconductor control element, 15 ... Resistor.

Claims (1)

[Claims] An AC power supply, a ballast, and a fluorescent lamp with a preheating electrode constitute a closed circuit, and between the non-power supply side preheating electrode terminal of the fluorescent lamp, the collector terminal and emitter of a transistor are provided with a base circuit that performs switching using a timer circuit. A fluorescent lamp lighting device characterized in that terminals are connected via a diode, and a Zener diode is connected between the base terminal of the transistor and the diode.