JPH037914Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a discharge lamp lighting device equipped with a timer circuit that obtains the preheating time of a discharge lamp, and the timer circuit allows the preheating time to be reliably obtained.

FIG. 1 shows a conventional discharge lamp lighting device, where 1 is an AC power source and 2 is a discharge lamp. 3 is an inverter circuit, which includes a pair of transistors 4, 5, which are alternately conductive;
An inverter transformer 8 having a primary winding 6 and a secondary winding 7 is provided. 9 is a rectifier circuit constituted by a diode bridge, and 10 is a smoothing capacitor. Reference numeral 12 denotes a dimmer, which includes a gate signal generation circuit 13 having a dimming volume, a dimmer switch 1 composed of a triax or a thyristor, etc.
4. The snubber circuit 17 is comprised of a capacitor 15 and a resistor 16. A timer circuit 18 includes a resistor 19, a capacitor 20, a charging circuit 21 made up of a capacitor, a thyristor 22, a timer switch 23 made up of a thyristor, and the like. 25 and 26 are current limiting resistors,
It is connected in parallel to the timer switch 23 of the timer circuit 18 via a diode 27.

Next, the operation will be explained. Gate signal generation circuit 13
When the dimmer switch 14 is turned on by the gate signal from the dimmer switch 14, the dimmer switch 14 is turned on by the AC power supply 1.
Smoothing capacitor 10, rectifier circuit 9, resistor 25,
A current is supplied to the inverter circuit 3 via 26, and the inverter circuit 3 oscillates at high frequency. However, since the current to the inverter circuit 3 is limited by the resistors 25 and 26, the filament of the discharge lamp 2 is preheated, but because the voltage generated in the secondary winding 7 is low, the discharge lamp 2 cannot be started immediately. Can not. When a predetermined preheating time elapses after turning on the dimmer switch 14, the capacitor 20 of the timer circuit 18 and the charging circuit 21 are charged via the resistor 19, and the timer switch 23 is turned on by turning on the thyristor 22, so that the AC Current is supplied from the power supply 1 to the inverter circuit 3 via the timer switch 23. As a result, the input voltage of the inverter circuit 3 increases, and the discharge lamp 2 starts and lights up. Therefore, the discharge lamp 2 can be lit after the filament of the discharge lamp 2 has been sufficiently preheated, the emitter of the filament can be prevented from being worn out due to blinking of the discharge lamp 2, and the life of the discharge lamp 2 can be extended.

However, when the dimmer switch 14 is off, the voltage between points A and B is
6. Impedance from the smoothing capacitor 10 and rectifier circuit 9 to the discharge lamp 2 and the power supply voltage V ₁
It is generated by dividing the voltage, and these values (impedance) differ, but for example, the power supply voltage
When V ₁ is 200V, the peak value of the voltage between points A and B is 80 ~
It may be 90V. In such a case, even when the dimmer switch 14 is off, current flows through the timer circuit 18 and the timer circuit 18 times up. does not work, discharge lamp 2
This results in the problem that the lifespan cannot be extended. Also, when the voltage between points A and B is relatively low,
Although the timer circuit 18 does not reach time-up, since the capacitor 21 that determines the time constant is charged at a low voltage, the time from when the dimming switch 14 is turned on until time-up occurs, that is, the preheating time. becomes shorter than the set time, and sufficient preheating time for the discharge lamp 2 cannot be obtained.

This invention solves the above problems, and its features are that a discharge lamp is connected to an AC power source via a rectifier circuit and an inverter circuit, and a charging circuit is installed between the rectifier circuit and the inverter circuit. A discharge lamp comprising: a timer circuit that obtains a preheating time for the discharge lamp according to the charging time of the charging circuit; a switch is provided in series between the AC power supply and the rectifier circuit; and a snubber circuit is connected in parallel to the switch. In the lighting device, a Zener diode is provided on the input side of the timer circuit.

Hereinafter, the present invention will be explained according to the illustrated embodiment.As shown in FIG.
A Zener diode 29 is provided in series with.

Therefore, if the Zener voltage of the Zener diode 29 is chosen equal to the peak value of the voltage between points A and B, then
The capacitor 20 is no longer charged by the current from the snubber circuit 17. As a result, charging circuit 2
1 is not charged, and there is no risk that the timer circuit 18 will unexpectedly time up or its preheating time will become shorter when the dimming switch 14 is turned off. Furthermore, according to the experimental results, there was no practical problem even if the Zener voltage of the Zener diode 29 was selected to be lower than the peak value of the voltage between points A and B to some extent. In other words, for example, the peak value of the voltage between points A and B is 85V.
In this case, if the zener voltage is set to 43V, the voltage applied to the timer circuit 18 side will be about half, and the time-up time of the timer circuit 18 will be only slightly shortened. Note that it is preferable to select the Zener voltage of the Zener diode 29 as low as possible because the loss caused by the Zener diode 29 is reduced.

In the embodiment described above, the gate signal of the dimmer switch 14 is varied in order to dim the light, but the present invention is not limited to the dimmer switch 14, and can be used to simply light the discharge lamp. The same can be applied to turning on and off a switch using a gate signal.

According to the present invention, since the Zener diode is provided on the input side of the timer circuit, when the switch provided between the AC power supply and the rectifier circuit is turned off, the timer circuit is connected from the AC power supply to the timer circuit. The flow of current can be effectively suppressed, and therefore, when the switch is turned on, the timer circuit can be reliably operated to provide sufficient preheating time for the discharge lamp. In addition, it has a simple structure, is easy to manufacture, and can be provided at low cost, and its practical effects are significant.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a conventional example, FIG. 2 is a waveform diagram for explaining operation, and FIG. 3 is a circuit diagram showing an embodiment of the present invention. 1... AC power supply, 2... Discharge lamp, 3... Inverter circuit, 9... Rectifier circuit, 14... Dimming switch, 17... Snubber circuit, 18... Timer circuit, 21... Charging circuit, 29... Zener diode.

Claims (1)

[Scope of utility model registration request] A timer circuit that connects a discharge lamp to an AC power source via a rectifier circuit and an inverter circuit, has a charging circuit between the rectifier circuit and the inverter circuit, and obtains the preheating time of the discharge lamp based on the charging time of the charging circuit. A discharge lamp lighting device in which a switch is provided in series between an AC power source and a rectifier circuit, and a snubber circuit is connected in parallel to the switch, characterized in that a Zener diode is provided on the input side of the timer circuit. Discharge lamp lighting device.