JPS6124795B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for lighting a discharge lamp such as a fluorescent lamp using a transistor inverter.

No. 1 disclosed in JP-A-54-141076 as a device for preventing rapid deterioration of the electrodes of a discharge lamp at the time of starting when a discharge lamp such as a fluorescent lamp is lit at high frequency using a transistor inverter. Conventionally, there was a device as shown in the figure.

In Figure 1, 1 is a current power supply, 2 is a switch, and 3
4 is a transistor inverter, 5a and 5b are transistors, 6a and 6b are starting resistors, 7a and 7b are resistors that supply the main base current to transistors 5a and 5b, 8 is an output transistor, and collector winding 8a, Consisting of a base winding 8b, an auxiliary winding 8c, an output winding 8d, and a filament winding 8e, 9 is a delay switch, 1
0a, 10b, and 10c are capacitors, 11 is a discharge lamp, and 11a and 11b are electrodes.

In the device configured as described above, switch 2
When closed, the inverter 4 starts oscillating operation, and voltage is generated in each winding of the transformer 8, and the electrodes 11a,
Preheat 11b. At this time, since the slow switch 9 is open, the transistors 5a and 5 of the inverter 4
Since current is supplied to the base only from the starting resistors 6a and 6b, the base current is insufficient and normal switching operation cannot be performed, and the voltage at the output winding 8d of the transformer 8 is reduced, so the discharge lamp 11 does not start. The electrode is in a preheated state.

Next, when the delay switch 9 closes, base current is supplied to the transistors 5a and 5b from the resistors 7a and 7b according to the voltage generated in the auxiliary winding 8c, so that normal switching operation is started. , the voltage of the output winding 8d also rises to a normal value, so the discharge lamp 11 starts and continues lighting, and the electrode 1
Since 1a and 11b were preheated, deterioration was prevented.

However, in such a conventional device, when the delay switch 9 is closed to start the discharge lamp, the output voltage of the auxiliary winding 8c is immediately reduced. This is because when the delay switch 9 is open, the transistors 5a and 5b are not performing normal switching operations as described above. For this reason, resistance 7
a and 7b must be set in anticipation of this voltage drop.After this, when normal switching operation begins, the voltage of the auxiliary winding increases, causing the base current of the transistor to become excessive, causing the switching of the transistor to increase. There was a risk that losses would increase.

The present invention seeks to eliminate the above-mentioned drawbacks. That is, after preheating the electrodes of the discharge lamp, the operation of the inverter is stopped, and then, when the inverter is operated again, the delay switch is closed, thereby avoiding a drop in the output voltage of the auxiliary winding when the delay switch is closed. The purpose is to provide a device that can do this.

Embodiments of the present invention will be described below based on the drawings. FIG. 2 is a diagram for explaining the operation of the apparatus of the present invention, and FIG. 3 shows an embodiment according to the present invention.

In Figure 3, 1 is a DC power supply, 2 is a switch, and 3
is a choke coil, 4 is a transistor inverter, 5a and 5b are transistors, and 6a and 6b are starting resistors, and the base current supplied from these resistors to transistors 5a and 5b reaches a value that cannot start the discharge lamp 11. It is set.
This point is similar to the device shown in FIG. 7a, 7b
is a resistor, 8 is an output transformer, 8c is an auxiliary winding, 8
d is an output winding, 8e is a filament winding for preheating the electrodes 11a and 11b, and 10a and 10
b, 10c are capacitors, 11 is a discharge lamp, 9 is a delay switch, 12 is an oscillation stop device for stopping the oscillation operation of the inverter 4, 12a, 12b
are switches whose opening and closing are controlled by the oscillation stop device 12, respectively.

The oscillation stop device 12 is connected to the DC power supply 1 as described later.
When the switch 2 is turned on, that is, the switch 2 is closed, the switches 12a and 12b are closed and opened after a predetermined period of time, and are closed after the discharge lamp is lit.

In the device configured as described above, switch 2
When the inverter 4 is closed, the switches 12a and 12b are closed by the operation of the oscillation stop device, and since the delay switch 9 is open, the inverter 4 starts the oscillation operation in the same way as the device shown in FIG. At this time, the transistors 5a and 5b of the inverter 4 cannot perform normal switching operations due to insufficient base current, and the voltage of the output winding 8d has decreased, as in the device shown in FIG. 11 does not start discharging, and the electrodes 11a, 11 do not start discharging due to the output of the filament winding 8e.
b is in a preheated state. This corresponds to the period from t ₁ to t ₂ in FIG. 2D. Next, when the switches 12a and 12b are opened by the operation of the oscillation stop device 12, the base current is no longer supplied to the transistors 5a and 5b of the inverter 4, and the oscillation operation is stopped. This situation is shown in Figure 2 (b) and (e), where the oscillation stops for a period from t ₂ to t ₄ , and then t ₄
This indicates that the switches 12a and 12b are closed again, thereby restarting the oscillation operation. here,
If the delay switch 9 is closed at t ₃ between t ₂ and _{t 4 as} shown in FIG. From this voltage, a sufficient base current is supplied to the transistors 5a and 5b through the resistors 7a and 7b, so that the discharge lamp starts. That is, at this time _t4 , since the delay switch 9 has already been closed, the base current is sufficiently supplied, so that a drop in the output voltage of the auxiliary winding 8c is avoided, and the electrodes 11a and 11b are also Since it is in a preheated state, deterioration of the electrode can be prevented. The time when the delay switch 9 closes is the time from t ₁ to t ₄ in FIG.
In other words, it is sufficient to close it before the oscillation stop state ends. The duration of the oscillation stop state may be a length of time that does not allow the preheated electrodes of the discharge lamp 11 to cool down.

FIG. 4 shows an example of the oscillation stop device 12. In the figure, 13 is an oscillation circuit, 14 is a lighting detection circuit, 15 is a transistor, and 16 is a relay. It is made up of contacts.

In this device, an oscillation circuit 13 generates a signal with an appropriate repetition period so that the on period of the transistor 15 is longer than the off period, and after the discharge lamp 11 is lit, it is discharged using a current transformer or the like. The operation of the inverter is maintained by the output signal of the lighting detection circuit 4 which detects the current of the lamp 11.

In addition to detecting the current, the means for detecting the lighting of the discharge lamp 11 is to detect the voltage of the discharge lamp, the output voltage of the output transformer, or to obtain the preheating time of the electrodes. A timer that generates a delay time may be provided, and the discharge lamp 11 may be turned on when the oscillation is stopped using its output.

The delay switch 9 includes electrodes 11a and 11b.
It is sufficient to open the circuit for a period of time to appropriately preheat the circuit and then close it, and the circuit may be configured to operate by a time constant circuit using a relay, or a semiconductor element such as a transistor or a thyristor.

In addition, in the explanation of the operation shown in FIG. 2, the time _t3 at which the delay switch 9 closes (ON) is
Although the inverter is shown to be between times t ₂ and _{t 4} when the inverter stops operating, it may be before t ₂ .

In the above embodiment, the case where the load discharge lamp is one lamp is shown, but the present invention can also be applied to a case where there are two or more lamps.

Further, the configuration of the inverter 4 is not limited to that shown in the embodiment, but may be any configuration as long as it can realize a preheated state of the electrodes due to insufficient base current of the transistors of the inverter.

The oscillation stop device 12 may also be of any type as long as it can stop the operation of the inverter 4 for a predetermined period.

As described above, according to the present invention, since the operation of the inverter is stopped and then restarted, there is an effect that the transistors of the inverter can be shifted to normal switching operation with an appropriate base current.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a conventional device, FIG. 2 is an explanatory diagram of the operation of the device according to the present invention, FIG. 3 is a circuit diagram showing an embodiment of the device according to the present invention, and FIG. 4 is a circuit diagram showing an embodiment of the device according to the present invention. FIG. 2 is a circuit diagram showing an example of an embodiment of an oscillation stop device used in the device. In the figure: 1 DC power supply, 4 inverters, 5a, 5b transistors, 9 delay switches, 11 discharge lamps, 11
A, 11b electrodes, and 12 oscillation stop devices are shown, and the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A transistor inverter that converts the power of a DC power source into AC power and lights up the discharge lamp, a preheating means that preheats the electrodes of the discharge lamp using the output voltage of the inverter, and a predetermined period of time when the DC power source is turned on; A delay switch that reduces the base current of a transistor constituting the inverter, reduces the output voltage of the inverter, preheats the electrodes, and after a predetermined period of time, supplies a predetermined base current to light the discharge lamp. In a device equipped with
A discharge lamp lighting device comprising an oscillation stop device that temporarily stops operation of the inverter after preheating the electrodes.