JPS62126595A - 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.

Conventional Technology 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. - The one-stone self-excited inverter circuit shown in Figure 4 is used as a high-frequency lighting device that is compact, lightweight, and low-cost. The capacitor 2 is connected to form a power supply circuit, and the resonance capacitor 3 and the switching transistor 8 are connected in series. Further, the primary winding 4a of the current limiting inductance element 4 and a fluorescent lamp 5 having a pair of electrodes sa and sb are connected in series, and the fluorescent lamp 5 is connected to a diode 6 as a starting circuit and a bidirectional semiconductor control element 7. series bodies are connected in parallel. One end of the secondary winding 4b of the current limiting inductance element 4 is connected to a transistor 8 via a pace current limiting capacitor 9.
The other end is connected to the negative terminal of the power supply circuit. In addition, a resistor 10 serves as a starting resistor, and a resistor 12 serves as a reset circuit for the base current limiting capacitor 9.
．． A series body of diodes 11 is connected.

The problem that the invention seeks to solve Problems with such a circuit will be described below.

First, commercial power is turned on and high frequency oscillation is started to keep the fluorescent lamp 6 lit. Next, when the commercial power supply is cut off, the electric charge charged in the smoothing capacitor 2 is transferred to the starting resistor 1o.
is discharged between the base and the emitter of the transistor 8 through the transistor 8. However, the starting resistor 10 is normally used to allow a small amount of base current to flow, and has a high resistance. As a normal constant, the capacitance value of smoothing capacitor 2 is 47μF starting resistor 10
Assuming that the resistance value of is 470Ω and the lamp voltage of 60 fluorescent lamps is 85V (zero-peak value), -p The relationship between the elapsed time after the power is cut off and the voltage of smoothing capacitor 2 is as shown in Figure 5. become. Further, the secondary voltage for keeping the fluorescent lamp 5 lit is determined by the voltage waveform of the resonant capacitor 3 (FIG. 3), and this secondary voltage is determined by the voltage of the smoothing capacitor 2. As a result, the discharge of the fluorescent lamp 6 is maintained for 1 to 11 seconds after the power is cut off. Also,
This discharge is a slight discharge state in which the current due to the residual charge of the smoothing capacitor 2 is small. At this time, when the power is turned on again, the load of the fluorescent lamp 5 (which can be thought of as a relatively low resistance load) is connected in parallel to the starting circuit (diode 6 and bidirectional semiconductor control element). However, there was a drawback in that it was not possible to obtain a starting voltage that would normally generate a high frequency and cause the transition to main discharge, and therefore a slight discharge state continued and a normal high frequency discharge did not occur.

Means for Solving the Problems The fluorescent lamp lighting device of the present invention connects a discharging resistor in parallel with the smoothing capacitor constituting the DC power supply, and when the power is turned on again, the voltage of the smoothing capacitor is lowered from the lamp voltage of the fluorescent lamp. The time constant between the capacitance value of the smoothing capacitor and the resistance value of the discharge resistor is determined so that the fluorescent lamp cannot maintain a slight discharge state due to the residual charge of the smoothing capacitor.

Immediately after the operating power supply is cut off, the lamp voltage of the fluorescent lamp becomes higher than the voltage of the smoothing capacitor, so that the fluorescent lamp is turned off without being turned on by slight discharge due to the residual charge of the smoothing capacitor. Therefore, even if the power is turned on again, a normal high-frequency main discharge will occur.

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

In FIG. 1, a rectifier 1 and a smoothing capacitor 2 are connected to a commercial power source, and a discharge resistor 13 is further connected in parallel with the smoothing capacitor 2. A resonance capacitor 3 and a switching transistor 8 are connected in series.

In addition, the primary winding 4+ of the current control inductance element 4
! L and a fluorescent lamp 5 having a pair of electrodes sa and 6bi are connected in series, and a starting circuit consisting of a series body of a diode 6 and a bidirectional semiconductor control element 7 is connected between the electrodes sa and sb of the fluorescent lamp 5. It is connected. One end of the secondary winding 4b of the current limiting inductance element 4 is connected to the pace, and the other end is connected to the negative terminal of the power supply circuit. Also,
A diode 11 is used as a reset circuit for the base current limiting capacitor 9. A resistor 12 is connected to the pace of the transistor 8, with a resistor 10 as a starting resistor.

Next, the operation of this circuit will be explained.

When commercial power is turned on, smoothing capacitor 2 is charged via rectifier 1, and transistor 8 is charged via starting resistor 1o.
Current flows to the 0 base, turning on the transistor 8. At that time, the collector current of the transistor 8 changes from the positive electrode of the smoothing capacitor 2 to the current limiting inductance element 4.
Flows from the primary winding 4a of the fluorescent lamp 6 to the electrode 6a of the fluorescent lamp 6 to the diode 6 to the bidirectional semiconductor control element 7 to the collector-emitter of the transistor 8 to the negative electrode of the smoothing capacitor.

The secondary winding 4 of the current limiting inductance element 4
Since an electromotive force is generated in the direction b that turns on transistor 8, transistor 8 remains on. Next, the collector current increases, and “c>hre・techa (h
re: current amplification factor I, two-pace current), then
Since the collector current is saturated, the electromotive force generated in the secondary winding 4b of the current limiting inductance element 4 is not in the cutoff direction of the transistor 8, and the transistor 8 is rapidly turned off. When the transistor 8 is turned off, a kick voltage due to the electromagnetic energy accumulated in the primary winding 4a of the current limiting inductance element 4 is applied to the fluorescent lamp 5, and the fluorescent lamp 6 starts discharging. At this time, a high frequency voltage shown in FIG. 3 is generated across the resonance capacitor 3, and if the lamp voltage of the fluorescent lamp 6 is lower than the voltage of the smoothing capacitor 2, the discharge becomes stable. Assume that the power is cut off while the fluorescent lamp 5 is kept lit in this manner.

In this example, the capacitance value of smoothing capacitor 2 is 47 μF1.
The resistance value of the discharge resistor 13 was set to 33Ω, and the lamp voltage of the fluorescent lamp 60 was set to 86V (zero-p peak value). Therefore, the time constant between the capacitance value of the smoothing capacitor 2 and the resistance value of the discharge resistor 13 is 1.6 seconds. FIG. 2 shows the elapsed time after power cutoff and the change in voltage of the smoothing capacitor 2. As can be seen from Fig. 2, the lamp voltage of the fluorescent lamp 6 becomes higher than the voltage of the smoothing capacitor 2 for more than 1 second after the power is cut off.9 Therefore, the fluorescent lamp 5 cannot maintain discharge, and the voltage of the smoothing capacitor 2 increases. The light is turned off without entering a slight discharge state due to residual charge.

Therefore, even if the power is turned on again, a kick voltage at startup is generated in the fluorescent lamp, resulting in a normal high-frequency main discharge. Note that normally, when using a mechanical switch, it is impossible to turn on the power again within one second after turning off the power.

Effect of the invention As described above, according to the present invention, the following effects can be obtained.

■ The fluorescent lamp becomes a normal high-frequency main discharge when restarted.

■ After the power is turned off, there is no slight discharge in the fluorescent lamp, so it is turned off immediately.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a fluorescent lamp lighting device according to an embodiment of the present invention, FIG. 2 is a diagram showing the relationship between elapsed time after power cutoff and smoothing capacitor voltage in the fluorescent lamp lighting device, and FIG. Figure 4 is a circuit diagram of a conventional fluorescent lamp lighting device, and Figure 5 shows the relationship between the elapsed time after power cutoff and the smoothing capacitor voltage in the fluorescent lamp lighting device. It is a figure showing a relationship. 1... Rectifier, 2... Smoothing capacitor, 3... Resonant capacitor, 4... Current limiting inductance element, 4a...1 Secondary winding, 4b... Secondary winding, 6... Fluorescent lamp, sa, 5b... Electrode, 6... Diode element, 7... ...bidirectional semiconductor element, 8.
... Transistor, 9 ... Pace current limiting capacitor, 10 ... Starting resistor, 11 ...
...Diode, 12...Resistor, 13...
...Resistance for discharge. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
Figure tJ, 0LInllll-寥) % E Breast Closure < s cc ) Figure 3 (0T

Claims (1)

[Claims] In a self-excited inverter type fluorescent lamp lighting device in which a DC power supply having a smoothing capacitor, a current limiting inductance element, a pair of electrodes, and a switching element are connected in series to a fluorescent lamp having a starting circuit in parallel, the smoothing A discharge resistor is connected in parallel with the capacitor, and when the power is turned on again, the voltage of the smoothing capacitor is lower than the lamp voltage of the fluorescent lamp, so that the fluorescent lamp cannot maintain a slight discharge state due to the residual charge of the smoothing capacitor. A fluorescent lamp lighting device characterized in that a time constant between a capacitance value of the smoothing capacitor and a resistance value of the discharge resistor is determined.