JPS6193594A - Discharge lamp lighting circuit - 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 Application of the Invention] The present invention relates to a discharge lamp lighting device that prevents flickering of a discharge lamp at the end of its life, and particularly relates to a discharge lamp lighting device that prevents the failure to restart due to voltage fluctuations. This is a characteristic circuit.

[Background of the invention]

FIG. 1 shows the gate of the thyristor described in Japanese Patent Laid-open No. 58-192293 which is controlled by a timer, so that the thyristor 4 will not become conductive unless the discharge lamp can be lit within about 2 seconds after the power is turned on.

Therefore, after that, the preheating operation and the pulse generation operation are also stopped, and the discharge lamp 3 remains in a non-lit state. Therefore, flickering of the discharge lamp 5 can be prevented even if the discharge lamp 3 enters the emissionless state at the end of its life.

However, if it is installed in a place with severe voltage fluctuations and the power supply voltage drops below the extinguishing voltage of the discharge lamp 3, the discharge lamp 3 will turn off, and even if the power supply voltage returns to the starting voltage 1 of the discharge lamp 5 in a few seconds, the Because the tie "f-circuit is operating, a phenomenon occurs in which the discharge lamp 3 cannot be lit again. [Object of the Invention] The object of the present invention is to provide a lighting device that does not prevent the lighting of the discharge lamp even under the influence of voltage fluctuations. Our goal is to provide the following.

[Summary of the invention]

The present invention provides a discharge lamp, an inductive ballast connected in series with the discharge lamp, a non-linear capacitor connected substantially in parallel with the discharge lamp, and a semiconductor connected in series with the filament of the discharge lamp. In a discharge lamp lighting device including a switch, a capacitor that is charged up to the tube voltage of the discharge lamp is connected in parallel with the discharge lamp 3, and this potential is used to control conduction of the semiconductor switch, thereby reducing the voltage. The thyristor 4 is made to temporarily conduct by utilizing the transient voltage change caused by the fluctuation.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described with reference to FIG. 2. The conduction of the thyristor 4 is controlled using the potential of the capacitor 13 connected in parallel with the discharge lamp 3.

When the power supply voltage is applied, the thyristor 4 becomes 9-6-14
, the thyristor 4 conducts and a preheating current flows, but - in phase 1, when the thyristor 4 is activated, a charging current flows through the nonlinear capacitor 5. Since the preheating current is an inductive ballast 2, its phase lags behind the power supply voltage, and when the preheating current becomes less than the holding current of the thyristor 4 and the thyristor 4 is turned off, a reverse voltage suddenly appears on the nonlinear capacitor 5. is applied, and the charge of the nonlinear capacitor 5 suddenly becomes saturated.

At this time, the charging current of the nonlinear capacitor 5 is cut off,
A pulse voltage is generated.

The discharge lamp 3 operates in the same way for each half cycle, and the discharge lamp 3 lights up in about 1 second.

After the discharge lamp 3 is lit, the terminal voltage of the capacitor 13.11 is v1.
31v14 is balanced by the following formula, and the thyristor 4 is not conductive, so there is no hindrance to the lighting operation of the discharge lamp.

vIs = (switch voltage of 6' +v14 + (voltage between 4 nodes and talk nodes) ・・・・・・・・・・・・・・・
...(1) On the other hand, if the discharge lamp 3 is not in the emission state,
If it is not possible to switch to lighting, vl31 to vl4 become the relationship of equation (1) after about 2 seconds, and the thyristor 4 is prevented from conducting. Therefore, both the preheating operation and the pulse generation operation are stopped. ○ In this way, by controlling the gate of the thyristor 4 with a timer, it is possible to prevent flickering at the end of the life of the discharge lamp 3. Assuming that the lamp is lit at a voltage of 1, the tube voltage at this time becomes a trapezoidal wave, and this voltage maintains the balance of Equation 1). However, the power supply voltage is 6
When the voltage drops to V,' which is less than the extinguishing voltage of 3, the lamp 3 starts to turn off, but the relationship in equation (1) remains unchanged, and the pipe wall end voltage at this time becomes a sine wave voltage 1'. Then, when the power supply voltage returns to vl, the discharge lamp 3 is silent, so v
A sinusoidal voltage of l is applied as the pipe wall end voltage. At this time, the difference voltage Vi-V,' between the pipe wall end voltages is transiently applied to the capacitor 13, and the potential of vl3 rises rapidly.

Therefore, the equilibrium state of equation (1) is disrupted, the electric and pressure sensitive resistor 6 becomes conductive, and the thyristor 4 becomes conductive again.

Therefore, preheating and pulse voltage generation operations start, and the discharge lamp 3
will be re-ignited.

In FIG. 1 as well, voltage differences v, -v,' across the tube corresponding to voltage fluctuations are applied, but because of the resistor 16, the potential of the capacitor 15 rises slowly, and the voltage sensing element 6 1, which causes conduction, causes a time delay. For this reason, although the balanced state of equation (1) is temporarily disrupted and the thyristor 4 becomes conductive, it immediately returns to the balanced state of equation (1), and the effect aimed at by the present invention is not achieved. In other words, as shown in ~2nd 1, the potential of the capacitor 15 is equal to the tube voltage 1
It is a prerequisite for operation that the capacitor 13 is charged with voltage and directly detects voltage fluctuations, and it is ineffective if an impedance such as the resistor 16 is connected in series to slow the change in the potential of the capacitor 13. It is.

〔Effect of the invention〕

According to the present invention, when a wide voltage fluctuation that causes a discharge lamp to go out occurs, it is possible to cause the discharge lamp to restart the lighting operation, thereby preventing the discharge lamp from being unable to be re-ignited. effective. In addition, the resistor 16 in Fig. 1 can be omitted, making it cheaper (even if the resistor 16 is omitted, there is no effect on performance).

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing a conventional device, and FIG. 2 is a circuit diagram showing one embodiment of the present invention. 1...Commercial AC' power supply, 2...Inductive ballast,
... Emitting '7'll lamp, 4. Thyristor, 5... Non-linear capacitor, 6.21... Voltage sensitive element, 9...
Backflow prevention capacitor, 13.14... Capacitor! , : Early 27

Claims (1)

[Claims] A discharge lamp comprising a discharge lamp, an inductive ballast connected in series with the discharge lamp, a non-linear capacitor connected substantially in parallel with the discharge lamp, and a semiconductor switch connected in series with the filament of the discharge lamp. A discharge lamp lighting device comprising: a capacitor charged to the tube voltage of the discharge lamp connected in parallel with the discharge lamp 3; and conduction of the semiconductor switch controlled by this potential.