JPS61190894A - Fluorescent lamp lighting device - 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 Industrial Application] The present invention relates to an improvement in a fluorescent lamp lighting device that starts and lights a fluorescent lamp by applying a pulse voltage to the fluorescent lamp. After that, a pulse voltage is applied to extend the life of the fluorescent lamp, and if the fluorescent lamp does not start after a certain period of time, the electrode preheating circuit is cut off to increase the safety of the device. It is.

[Prior art and its problems]

FIG. 2 shows an example of a fluorescent lamp lighting device for starting and lighting a fluorescent lamp by applying a pulse voltage to the fluorescent lamp. This involves connecting a fluorescent lamp 3 to an AC power source 1 via an inductive ballast 2, and connecting a series circuit of a diode 5 and a thyristor 6 to the non-power side of electrodes 4m and 4b of the fluorescent lamp 3. , Furthermore, in parallel with the same circuit, a parallel circuit of a diode T and a resistor 8 and a nonlinear capacitor 9 are connected.
This is a series circuit connected to the When the power supply voltage shown by the dotted line in FIG. 3 is applied to this circuit, the voltage across the resistor 100 gradually increases during the positive half cycle of the power supply voltage.At a phase angle θ1 exceeding the Zener voltage of the rezener diode 11, the thyristor 6 is activated. Turn on. Add to this ballast 2, electrode 4m, diode 5, thyristor 6, electrode 4
A current flows through b to preheat the electrodes 4m and 4b. When the power supply voltage becomes a negative half cycle, the preheating current becomes zero at a phase angle θ2 near the peak value of the power supply voltage, and the thyristor 6 is turned off. At the same time, since a voltage near the peak value is applied to the nonlinear capacitor 9, the nonlinear capacitor 9 is charged via the diode 7. This nonlinear capacitor 9 has a hysteretic voltage-charge characteristic as shown in Figure 7(a), so when the charging voltage reaches a certain value, the charging current suddenly decreases as shown in Figure 7(color), and the current The change creates a pulsed voltage in the ballast. Thereafter, by repeating the above operation, the electrodes 4m and 4b are preheated, and finally a discharge occurs between the electrodes 4a and 4b, and the fluorescent lamp 3 is activated. After activation, only a lamp voltage lower than the power supply voltage is applied to the gate circuit of the thyristor 6, so the thyristor 6 is not turned on and the fluorescent lamp 3 continues to stably light.

Such a lighting device has the advantage that the time required to start the fluorescent lamp is short and its life as a lighting device is semi-permanent.However, on the other hand, when AC power is turned on, the fluorescent lamp 3
Since the pulse voltage is applied every cycle before the electrodes 4m and 4b are sufficiently preheated, there is a drawback that the life of the fluorescent lamp is shortened. Also, diode 5
The current flowing in the series circuit of Cyrisk B and Cyrisk B is a half wave, and has a higher DC component than a full wave, so a large preheating current flows even when starting with a glow lamp. This is convenient for starting the fluorescent lamp, but in fluorescent lamps at the end of their lifespan, the electrode emitters are scattered and the fluorescent lamp cannot be started even if a pulse voltage is applied. If the preheating current continues to flow, the temperature of the ballast will rise, potentially leading to a fire.

[Purpose of the invention]

The present invention was made in view of the above-mentioned drawbacks.
It is an object of the present invention to provide a fluorescent lamp lighting device that prevents shortening of the life of the fluorescent lamp and improves the safety of the device.

[Structure and operation of the invention]

FIG. 1 shows an embodiment of a fluorescent lamp lighting device according to the present invention. In the figure, 1 is an AC power supply, 2 is an inductive ballast, and 3 is an inductive ballast.
is a fluorescent lamp, and 4m+4b is an electrode. This electrode '4a+
A series circuit of a diode 5 and a thyristor 6 is connected to the non-power supply side of 4b, and a series circuit of a thyristor 7 and a resistor 8 and a nonlinear capacitor 9 are connected in parallel with the series circuit. . 1o and 11 are gate circuits for the thyristors 6 and T, respectively. Reference numeral 12 is a time constant circuit for gradually delaying the phase angle of the thyristor by 1 and making the thyristor 6 non-conductive after a certain period of time. Now, suppose that an alternating current voltage with a phase angle θσ as shown by the dotted line in FIG. 4 is applied to the device. Then, since the capacitor 121 of the time constant circuit 12 is not charged at the initial stage of startup, the power supply voltage is lower than that of the Zener diode 1.
When the Zener voltage rises to 22, current begins to flow into the gate circuit 10. When the voltage of the capacitor 101 becomes higher than the Zener voltage of the Zener diode 1G'2, the thyristor 6 is triggered at the phase angle θ1 and becomes conductive.

As a result, current flows through the ballast 2, the electrode 4ax diode 5, the thyristor 6, and the electrode 4bt.
4b is preheated. This preheating current becomes zero at the phase angle θ2 of the negative half cycle of the power supply voltage, and the thyristor 6 is turned off. Then, a voltage near the negative peak value is applied between the electrodes 4a and Jb, but the thyristor 7 connected in series to the nonlinear capacitor 9 remains turned off.

The voltage near the peak value is generated by the nonlinear capacitor S and the resistor 8.
It will be applied to the series circuit with.

However, when a series circuit of a nonlinear capacitor and a resistor is connected to an AC power source via a stabilizer, the voltage-charge characteristic of the nonlinear capacitor becomes as shown in Figure 8 (a), and the voltage-current relationship at that time is Even if the voltage shown in FIG. 8(b) is applied, the pulse voltage generated in the ballast is extremely low and cannot be used to start the fluorescent lamp.

Also, the voltage near this negative peak value is resistor 111°112
Since it is also applied to the series circuit of
Electrolytic capacitor 114 is charged. However, at this time, the voltage across the charged electrolytic capacitor 114 is much lower than the voltage across the resistor 1110 and the turn-on voltage of the constant voltage trigger element 115 in the first cycle. At the next cycle θ5, the resistor 123, Zener diode 122, and diode 1 are connected in the previous cycle.
24. Since the charging voltage of the capacitor 121 charged via the resistor 103 and the capacitor 101t is increasing, when the phase angle becomes the sum of the charging voltage and the Zener voltage of the Zener diode 123, the current flows into the gate circuit 10 again. flows. When the voltage across the resistor 1030 exceeds the Zener voltage of the Zener diode 102, the thyristor 6 is turned on again at a phase angle of θ4 to flow a preheating current.

By repeating this cycle, the turn-on phase angle of the thyristor 6 is gradually increased by the charging voltage of the capacitor 121. - By repeating the above cycle, the charging voltage of the electrolytic capacitor 114 gradually increases,
When the voltage exceeds the turn-on voltage of constant voltage trigger element 115, current flows into the gate of thyristor 1 and thyristor T is turned on. Here, thyristor T
The electrolytic capacitor 114 and the resistor 1 are connected so that the trigger current flows until the next negative half cycle after the cycle in which the
By setting a time constant of 16, when the thyristor 6 is turned off when the electrode preheating current is zero, a voltage near the negative peak value is applied to the series circuit of the nonlinear capacitor 9 and the thyristor 7 in a conductive state.

However, if a nonlinear capacitor and a parallel circuit of a resistor and semiconductor rectifying element are connected in series to an AC power source via a stabilizer, and the resistor is inserted only in one direction from the nonlinear capacitor, the voltage of the nonlinear capacitor - The charge characteristics are as shown in No. 90 (&), and the voltage at this time -
The relationship between the currents is as shown in FIG. 9(b).

Therefore, as described above, the charging voltage of the nonlinear capacitor t9 decreases rapidly in the direction in which the nonlinear capacitor is provided, and a pulse voltage is generated during stabilization at the phase angle θ5. This first
Since the electrodes 4m+4b have been sufficiently preheated by the half-wave preheating current flowing through the diode 5 and the cyrisk 6 over several to several tens of cycles until the pulse voltage of 1 is generated, the fluorescent lamp 3 is started immediately. Furthermore, even if the fluorescent lamp does not start up due to this first pulse voltage, the above operation is generally repeated). The fluorescent lamp is activated by the third pulse voltage.

However, if the electrode emitter is scattered and the fluorescent lamp cannot be started even if a pulse voltage is applied, as is the case with fluorescent lamps at the end of their lifespan, the phase angle of turn-on of the thyristor 6 is gradually delayed by the charging voltage of the capacitor 121 from the Zener voltage of the Zener diode 122, and the conduction angle of the thyristor 6 gradually becomes smaller as shown in FIG. Then, the charging voltage of the capacitor 121 gradually increases, and when the peak value of the secondary side of the fluorescent lamp becomes equal to the sum of the Zener voltage of the Zener diode 122 and the charging voltage of the capacitor 121, the thyristor 6 is turned on. It becomes non-conductive. With this, the 6th
As shown in the figure, it is possible to prevent the preheating current from continuing to flow when the fluorescent lamp does not start, thereby preventing the temperature rise of the ballast and the occurrence of a fire associated with it. In the above case, the Zener voltage of the Zener diode 122 must be set to a value that will not turn on the thyristor 4 due to the re-ignition voltage of the fluorescent lamp after discharge. If the phase angle at which the thyristor 4 is turned on is early, even if the fluorescent lamp is activated by the pulse voltage in the negative half cycle, the thyristor 4 will be turned on in the positive half cycle.
This is because subsequent discharge cannot be maintained.

〔Effect of the invention〕

As explained above, in the present invention, since the electrodes of the fluorescent lamp are sufficiently preheated before starting the fluorescent lamp, shortening of the life of the fluorescent lamp can be prevented. In addition, if the fluorescent lamp does not start even after applying a pulse voltage, the preheating current of the fluorescent lamp is gradually reduced by gradually delaying the turn-on phase angle of the thyristor in the preheating circuit, and eventually shuts off. Therefore, abnormal temperature rise of the ballast can be prevented.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a fluorescent lamp lighting device according to the present invention, FIG. 2 is a circuit diagram of a conventional fluorescent lamp lighting device, and FIG. 3 is a voltage waveform diagram at the end of the fluorescent lamp in the circuit shown in FIG. Figures 4 and 5 are voltage waveform diagrams at the end of the fluorescent lamp in the circuit shown in Figure 1, Figure 6 is a diagram of the preheating current waveform of the fluorescent lamp in the circuit shown in Figure 1, and Figures 7 (a) to 9. 6) is a voltage-charge characteristic diagram and a voltage-current characteristic diagram of a nonlinear capacitor in the circuit of FIG. 1 or the circuit of FIG. 2. In Fig. 1, 1... AC power supply, 2... Inductive ballast, 3... Fluorescent lamp, 4a, 4b... Electrode, 5... Diode, 6
．． 7... Semiconductor switch element, 8... Resistor, 9...
...Nonlinear capacitor, 10.11...Gate circuit,
12...Time constant circuit. Figure 3 Figure 4 Figure 5 Ship f Right view

Claims (2)

[Claims] (1) A fluorescent lamp connected to an AC power source via an inductive ballast, and a first semiconductor switch element and a diode connected in parallel to the fluorescent lamp on the non-power side of the electrode of the fluorescent lamp. a preheating circuit consisting of a series circuit of a non-linear capacitor and a second semiconductor switch element connected in parallel to the fluorescent lamp;
a gate circuit that increases the phase angle that makes the second semiconductor switch element conductive from a constant phase angle over time after the AC power is turned on, and finally makes the second semiconductor switch element conductive; 1. A fluorescent lamp lighting device comprising: a gate circuit that generates a signal to conduct at fixed time intervals until the device is activated. (2) Claims characterized in that the gate circuit of the first semiconductor switching element is configured to be controlled by a time constant circuit formed by connecting a capacitor charging/discharging circuit and a Zener diode in series. The fluorescent lamp lighting device according to item 1.