JPS6011439B2 - discharge lamp lighting device - Google Patents

Description

Detailed Description of the Invention The present invention improves the flickering life of the lamp by heating the electrodes sufficiently and then applying a pulse voltage to turn on the discharge lamp. This relates to a star light for discharge lamps.

The present invention will be explained in detail below with reference to Examples.

FIG. 1 shows the basic configuration of an embodiment of the present invention. In the figure, 1 is an AC power source, 2 is a ballast, 3 is a discharge lamp having a heating element electrode, 4 is a noise prevention capacitor, and 5 is a starter circuit according to the present invention. 6 is a semiconductor switching element with a control pole such as an SCR having gate turn-off characteristics, hereinafter referred to as S
Represented by CR.

7 and 8 are resistors, which together with a capacitor 9 form a trigger circuit for turning on the switch element 6.

10 is a current or charge detection circuit, 11 is a switch, 12 is a resistor, and 13 is a capacitor.

Lo to 13 form a trigger circuit for turning off the switch element 6. The current-voltage characteristics of the detection circuit 10 are as shown in A to C in FIG. 4, where the voltage is proportional to the current up to a certain current value, and has switching characteristics at a predetermined voltage. The switch 11 is a switch that turns on when the sum of the voltages of the capacitor 13 and the detection circuit 10 exceeds a predetermined value.
A switch element such as R can be used. 5th action
This will be explained using figures.

In FIG. 5, A shows the voltage waveform of the power supply 1, V shows the voltage waveform across the lamp, and 1 shows the current waveform flowing through the ballast. C is a voltage generated in the detection circuit 10, which becomes almost maximum at a predetermined current value, and becomes a signal for triggering the switch 11 around IV at its peak value. The second voltage is the voltage of the capacitor 13, which is gradually charged over several to several tens of cycles as shown in FIG. When the power is turned on, the SCR
As the power supply voltage increases in the forward direction of SCR 6, the gate potential increases via resistor 7, and SCR 6 turns on at a certain value.

This causes a current to flow through the ballast 2, both electrodes of the lamp 3, and the switching element 6, and in the blocking direction of the SCR 6, a power supply voltage is generated across the lamp. While repeating this operation every cycle, the electrodes of the lamp 3 are heated. For example, if the detection circuit 10 is provided with a current/voltage characteristic as shown in FIG. 4C, a waveform as shown in FIG. 5' will be obtained. Further, the capacitor 3 is gradually charged by the blocking voltage of the SCR 6 through the resistor 12 as shown in FIG. 5-2. During this time, the switch 11 is off. capacitor 13
When the voltage reaches a certain value, the switch 11 is turned on at the peak value of the voltage of the detection circuit 10 or at a time tp just before that voltage by the sum of this voltage, the voltage of the detection circuit 10, and the voltage between the gate and cathode of the SCR 6. This results in
A reverse bias voltage is applied between the cathode and gate of the SCR 6 by the voltage of the capacitor 13, and the SCR 6 is turned on. The current value at this time is approximately the value of 1 shown in FIG. 4, and thereby the pulse voltage generated by the ballast can also be kept at an approximately constant value. Since the filament of the lamp is sufficiently heated at time tp, the lamp immediately returns to normal lighting after the pulse is applied. The values of the resistors 7 and 8 and the capacitor 9 are determined so that the SCR 6 does not turn on because the voltage across the lamp decreases after lighting. Second
The figure shows a specific example, in which the detection circuit 10 is constituted by a parallel circuit of a resistor 15 and a Zener diode 16.

The Zener diode 16 can be replaced by one or more diodes, and the current-voltage characteristics at this time will be as shown in FIG. 4A. In this case as well, the same operation as in the case of the above operation explanatory diagram can be expected. However, in this case SCR
Due to the gate-to-cathode voltage of 6, the switch 14 may operate at a current value greater than 1. To prevent this, instead of the Zener diode 16, use a 16"
It is recommended to use a voltage sensitive switch such as a Shockley diode or a Biac. In that case, the current/voltage characteristics will be as shown in Figure 4 or C, and the operation will be stable. The switch 14 may be any voltage sensitive switch with an appropriate voltage, and here an S spot is used. Note that if the switch 14 is unidirectionally conductive, the resistor 12 can be omitted. Third
The figure shows another embodiment, in which the detection circuit 10 is composed of a Zener diode 20, resistors 21 and 23, and a capacitor 22.

The relationship between the voltage across the resistor 21 and the cathode current of the SCR 6 is approximately as shown in FIG. 4C. The Zener diode 20 may be one to several diodes, such as 20'.
Further, the charging circuit for the capacitor 13 is configured as a double integral by resistors 17 and 19 and a capacitor 18. As is clear from the above description, in the present invention, the pulse voltage is applied after the electrodes are sufficiently heated, so that the life of the lamp is extended. In addition, it is not stable due to half-wave lighting caused by insufficient electrode heating or abnormal lighting that stabilizes in a slight discharge state. Further, even if a pulse is generated before the electrode is sufficiently heated, the pulse will continue to be generated, so stable lighting operation is possible.

[Brief explanation of the drawing]

FIG. 1 shows an embodiment of the present invention, FIGS. 2 and 3 show examples of specific configurations of the present invention, FIG. 4 shows current-voltage characteristics of the detection circuit, and FIG. 5 shows an operating waveform diagram. . Ji 1 Bacteria Z Z Arashi Ji 3 Bacteria Boar 4 Crane and Chrysanthemum S

Claims (1)

[Claims] 1. In a discharge lamp lighting device consisting of an AC power supply, an inductive ballast, a discharge lamp with a preheating electrode, and a starter circuit, the starter circuit is connected between the non-power supply side terminals of the preheating electrode of the discharge lamp, A semiconductor switch with a control pole conducts at a predetermined value of forward voltage, and when the power supply voltage is a forward voltage with respect to the switch, the current or charge at the current output end of the switch is detected and the voltage is almost the maximum voltage at a predetermined current value. A first circuit is connected between the detection circuit and the control pole of the switch to generate impedance due to the voltage across the discharge lamp when the power supply voltage is in the blocking direction with respect to the switch. and a voltage sensitive switch that becomes conductive when the sum of the charging voltage of the capacitor and the voltage generated by the detection circuit reaches a predetermined voltage value. ,
A discharge lamp lighting device characterized in that, when the switch is made conductive, the charged voltage of the capacitor is applied to the control pole of the switch with a polarity that blocks current flow, thereby rendering the switch non-conductive.