JPS629680Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a lighting device for a discharge lamp such as a fluorescent lamp using a transistor inverter.

2. Description of the Related Art It has been known for a long time to operate a discharge lamp at a high frequency using a transistor inverter from a DC power source. FIG. 1 is a circuit diagram showing a conventional discharge lamp lighting device that performs such an operation. In FIG. 1, A indicates a transistor inverter, which is of a type called a push-pull transistor inverter. In FIG. 1, when the DC power supply 1 is turned on by turning on the switch 2, the DC power supply 1 connects the switch 2 to the resistor 6.
A base current flows to the bases of transistors 3a and 3b via a and 6b. And inductor 4
The voltage of the DC power supply 1 is applied to the collector winding 5N of the oscillation transformer 5 through the base feedback winding 5B of the oscillation transformer 5, and the transistor 3
a and 3b repeat opening and closing alternately. As a result, a collector current flows through the collector winding 5N, and a high frequency voltage is generated in the winding 5F and the secondary winding 5S of the oscillation transformer 5, thereby lighting up the discharge lamp 8.

Here, since the discharge lamp 8 is designed to be lit via the capacitor 7, in this type of transistor inverter A, the output frequency ₂ after the discharge lamp 8 is lit is lower than the output frequency ₁ before the discharge lamp 8 starts lighting. Become. For this reason, the voltage (filament voltage) of the electrodes 8a and 8b of the discharge lamp 8 decreases to an appropriate value after the discharge lamp 8 is turned on due to the presence of the capacitors 9a and 9b.

By the way, in such a conventional discharge lamp lighting device, when starting the discharge lamp 8, a high starting voltage is generated in the secondary winding 5S of the oscillation transformer 5 at the same time as preheating of the electrodes 8a and 8b starts. , electrode 8
If discharge is forcibly started before sufficient preheating of electrodes 8a and 8b is performed, there is a risk that electrodes 8a and 8b of discharge lamp 8 will rapidly deteriorate and have a short lifespan.

This idea was made to eliminate the above-mentioned drawbacks of the conventional method, and after preheating the electrodes of the discharge lamp,
An object of the present invention is to provide a discharge lamp lighting device that can prevent rapid deterioration of electrodes by applying a voltage necessary for starting the discharge lamp.

Hereinafter, embodiments of the discharge lamp lighting device of this invention will be described based on the drawings. FIG. 2 is a circuit diagram showing the configuration of one embodiment. In FIG. 2, the same parts as in FIG. 1 will be described with the same reference numerals. In the embodiment shown in FIG. 2, a timer circuit 12 and a switch device 1 are added to the circuit shown in FIG.
0 and a resistor 11 are added.

That is, the positive electrode of the DC power supply 1 is connected to the bases of the transistors 3a and 3b via the switch 2 and the resistors 6a and 6b, and also to the midpoint of the inductor 4 and the collector winding 5N of the oscillation transformer 5. There is. Both ends of the two collector windings are connected to the collectors of transistors 3a and 3b. The emitters of the transistors 3a and 3b are connected to the negative pole of the DC power supply 1 via a switch device 10.

Further, the oscillation transformer 5 has a base feedback winding 5B,
It has a winding 5F and a secondary winding 5S. Both ends of the base feedback winding 5B are connected to the bases of the transistors 3a and 3b. The secondary winding 5S is connected to both ends of the discharge lamp 8 via a capacitor 7.
Also, each of the two windings 5F has a capacitor 9
It is connected to electrodes 8a and 8b of the discharge lamp 8 via a and 9b. Thus, a transistor inverter A is configured. The points up to this point are the same as in FIG.

However, in this invention, as described above, the timer circuit 12, the switch device 10, and the resistor 11 are added to the transistor inverter A. As the switch device 10, a case is shown in which a transistor is used. The emitter of the transistor is connected to the negative electrode of the DC power supply 1, and the collector is connected to the emitters of the transistors 3a and 3b. A resistor 11 is connected between the emitter and collector of the transistor of the switch device 10.

The base of the transistor of the switch device 10 is controlled by the output of the timer circuit 12. That is, the timer circuit 12 has a series circuit of a resistor 13 and a capacitor 14 connected through the switch 2 between the positive and negative poles of the DC power supply 1. The connection point between the resistor 13 and the capacitor 14 is connected to the base of the transistor of the switch device 10 via a constant voltage diode 15.

Next, the operation of the discharge lamp lighting device of the present invention configured as above will be described. First, when the switch 2 is turned on and the DC power source 1 is turned on,
A capacitor 14 in a timer circuit 12 is charged through a resistor 13, and the charging voltage of this capacitor 14 rises with a time constant determined by the resistor 13, but the switch device 10 is cut off until the charging voltage reaches the Zener voltage of a constant voltage diode 15. Therefore, a DC voltage obtained by dividing the voltage of the DC power source 1 by the resistor 11 is applied to the transistor inverter A.

At this time, transistor inverter A operates in the same manner as explained in FIG.
When the value of the resistor 11 is set so that % is applied, the oscillation transformer 5 of the transistor inverter A
The output voltage of the secondary winding 5S is low, and the discharge lamp 8 does not start (discharge starts). And in this period,
The electrodes 8a and 8b of the discharge lamp 8 continue to be preheated by the output voltage from the winding 5F (filament winding).

Next, when the predetermined set time of the timer circuit 12 has elapsed and the charging voltage of the capacitor 14 between the timer circuits 12 becomes sufficiently high, the switch device 10 becomes conductive. Therefore, almost all of the voltage of the DC power supply 1 is applied to the transistor inverter A through the switch device 10. Therefore, the output voltage of the secondary winding 5S of the oscillation transformer 5 becomes high enough to start the original discharge lamp 8.
As a result, the discharge lamp 8 whose electrodes 8a and 8b have been sufficiently preheated can be started and lit.

In addition, as in the case shown in FIG. 1, the frequency generated by the transistor inverter A decreases while the discharge lamp 8 is lit compared to before the lighting starts, so that the electrodes are connected via the capacitors 9a and 9b. The value of the preheating voltage to 8a, 8b decreases.

FIG. 3 is a circuit diagram showing only the parts different from FIG. 2 in a second embodiment of the discharge lamp lighting device of this invention. In FIG. 3, the push-pull type transistor inverter A is used in the same way as in FIG. It is connected between both ends of line 5N. The leakage inductance of the oscillation transformer 5 sets the current of the discharge lamp 8 to a predetermined value.

In this case, since the voltage of the secondary winding 5S when the discharge lamp 8 is not started is significantly reduced by the lighting of the discharge lamp 8, the switch device 10 is changed as shown in the embodiment of FIG. After the discharge lamp 8 lights up after reaching the conductive state from the cutoff state, the electrode 8 of the discharge lamp 8
The preheating voltages of a and 8b can be made sufficiently low.

FIG. 4 is a circuit diagram showing only the parts of the third embodiment of the discharge lamp lighting device of this invention that are different from the embodiment of FIG. 2. In FIG. 4 as well, the same parts as in FIG. 2 will be described with the same reference numerals. In this figure 4, DC power supply 1
This device is particularly suitable when the current is a pulsating direct current that has been full-wave rectified from an alternating current power supply, and in particular, the timer circuit 12 and the switch device 10 are different.

That is, in the timer circuit 10, a series circuit of a diode 17 and a capacitor 18 is connected between the positive and negative poles of the DC power supply 1 via the switch 2.
Resistor 13 and capacitor 1 in parallel with capacitor 18
4 series circuits are connected. The connection point between the capacitor 14 and the resistor 13 is connected to the gate of the switch device 10 through a trigger element 20. As the switch device 10, a thyristor is used in this embodiment. Also, the anode of the thyristor, the diode 17 and the capacitor 18
A resistor 19 is connected between the connection points. The other configurations are the same as in FIG. 2.

Next, the operation of the embodiment shown in FIG. 4 will be explained. Diode 1 input voltage of timer circuit 12
7 and a capacitor 18, and the smoothed voltage charges the capacitor 14 through the resistor 13. When the terminal voltage of this capacitor 14 rises above a predetermined level, the trigger element 20 breaks over and the thyristor used as the switch device 10 becomes conductive.

As a result, transistor inverter A (fourth
Almost all the voltage of the DC power supply 1 is applied to the discharge lamp 8 (not shown in the figure), and the discharge lamp 8 (not shown in FIG. 4) is turned on in the same manner as in FIG. 2. However, in FIG. 4, when the thyristor becomes conductive, the current flowing through the resistor 19 causes the thyristor to remain conductive. In some cases, when obtaining DC power from AC power, a trigger signal such as a phase control pulse may be applied to the thyristor of switch device 10 to light discharge lamp 8.

FIG. 5 is a circuit diagram showing a fourth embodiment of the discharge lamp lighting device of this invention. In the case of FIG. 5, the power supply of the timer circuit 12 is connected to the transistor inverter A.
This is obtained from the auxiliary winding 5A provided in the oscillation transformer 5, and the discharge lamp 8 is lit by the same operation as shown in FIG.

That is, a series circuit of a diode 19 and a capacitor 18 is connected between both ends of the auxiliary winding 5A, and one end of the capacitor 18 is connected to the negative electrode of the DC power supply 1. A series circuit of a resistor 13 and a capacitor 14 is connected in parallel to the capacitor 18 . A connection point between the resistor 13 and the capacitor 14 is connected to the base of a transistor serving as the switch device 10 via a constant voltage diode 15.
The other configurations are the same as in FIG. 2.

In this manner, by obtaining power for the timer circuit 12 from the auxiliary winding 5A of the oscillation transformer 5, the voltage across the auxiliary winding 5A is rectified by the diode 19 and smoothed by the capacitor 18. capacitor 18
The voltage across the capacitor 14 is passed through the resistor 13.
The charging voltage is applied to the constant voltage diode 1
When the Zener voltage reaches 5, the transistor of the switch device 10 becomes conductive, and the normal voltage of the DC power supply 1 is applied to the transistor inverter A, and the discharge lamp 8 is lit in the same manner as in each of the above embodiments.

In this embodiment, the timer circuit 12 can be operated to make the switch device 10 conductive only when the transistor inverter A operates normally, that is, when a high frequency voltage is generated in the oscillation transformer 5. Therefore, it is possible to prevent the unnecessary operation of making the switch device 10 conductive when the inverter A is out of order or the like.

In other words, also in FIG. 5, the timer circuit 1
Unlike the above embodiments, the power source for the discharge lamp 8 is taken from the auxiliary winding 5A of the oscillation transformer 5, and while the capacitor 14 is charged to a predetermined voltage, the discharge lamp 8
The electrodes 8a and 8b are preheated as in each of the above embodiments.

Furthermore, in each of the embodiments shown in FIGS. 2 to 5, a push-pull type transistor inverter is used as the transistor inverter A, but the voltage of the DC power supply 1 is changed by the resistor 11 at the time of starting. Of course, a transistor inverter having another configuration may be used, since it is only necessary to divide the voltage and apply the voltage.

In addition, in the above description of the embodiment, the case where the discharge lamp 8 of the load is one lamp is described, but it is obvious that the case can also be applied to a case where there are two or more lamps. The circuit 12 is not limited to those of the embodiments described above, and may be any circuit that can keep the switch device shut off during the period of preheating the electrodes 8a, 8b of the discharge lamp 8, and then turn on the circuit. If the DC power supply 1 is frequently interrupted, for example, a suitable discharge circuit may be provided in a portion of the timer circuit 12 corresponding to the capacitor 14. In addition, the electrode 8 of the discharge lamp 8
Although a case is shown in which a resistor 11 is used to divide the voltage of the DC power supply 1 during preheating of the components a and 8b, it goes without saying that voltage dividing means using other impedance elements may be used.

FIG. 6 shows only the portions of the fifth embodiment of the discharge lamp lighting device of this invention that are different from those in FIG. 2. In this Figure 6,
This is an example showing a modification of the preheating means, in which a capacitor 21 is connected to both ends of the secondary winding 5S of the oscillation transformer 5, and one end of the secondary winding 5S is connected to the primary winding of the transformer 22. and is connected to the electrode 8a of the discharge lamp 8. The other electrode 8b is connected to the other end of the secondary winding. The transformer 22 has two secondary windings 22F ₁ and 22F ₂ .

The secondary winding 22F ₁ and one winding 5F (filament winding) are connected in series, and both ends of this series circuit are connected to the electrode 8a of the discharge lamp 8. Similarly, the secondary winding 22F ₂ and the other winding 5F
(filament winding) are connected in series,
Both ends of the series circuit are connected to the electrode 8b of the discharge lamp 8.

With this configuration, when preheating the electrodes 8a and 8b of the discharge lamp 8, the secondary winding 22F ₁ of the transformer 22 and one winding 5F, and the secondary winding 22F ₂ and the other winding 5F Because they are connected in series,
The respective induced voltages are added and applied to the electrodes 8a and 8b of the discharge lamp 8, thereby shortening the preheating time.

FIG. 7 is a block diagram showing a sixth embodiment of the discharge lamp lighting device of this invention. In the case of FIG. 7, the capacitor 23 is connected in parallel with the transistor inverter A by utilizing the fact that the switch device 10 is in a cut-off state when the DC power supply 1 is turned on. The presence of the resistor 11 prevents the surge voltage from being applied to the transistor inverter A.

By appropriately setting the capacitance of this capacitor 23, even when the DC power supply 1 is a pulsating current that is not smoothed, by using a thyristor as the switch device 10, the necessary holding current can be supplied from the capacitor 23 to the discharge lamp. It can also be supplied while 8 is on.

Although not shown in the figures in each of the above embodiments, in addition to controlling the conduction of the switch device 10 with the timer circuit 12, it is also possible to control the conduction of the switch device 10 by controlling the preheating current flowing through the electrodes of the discharge lamp 8 or the voltage applied to the electrodes. Then, the preheating state of the electrodes 8a and 8b of the discharge lamp 8 may be detected and the switch device 10 may be turned on.

As described above, according to the discharge lamp lighting device of this invention, when starting the discharge lamp, the electrodes are first preheated,
Since a voltage sufficient for starting the discharge lamp is then applied to the discharge lamp, there is an advantage that rapid deterioration of the electrodes does not occur when the discharge lamp is started.

The switch device also has a means (resistor 1 in Figure 4) for maintaining the conduction state once it becomes conductive.
9, a capacitor 23) shown in FIG. 7 is attached, and the discharge lamp can be lit stably.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram of a conventional discharge lamp lighting device, Figure 2 is a circuit diagram of a conventional discharge lamp lighting device.
The figure is a circuit diagram showing one embodiment of the discharge lamp lighting device of this invention, and FIGS. 3 and 4 are different from FIG. 2 in the second and third embodiments of the discharge lamp lighting device of this invention, respectively. FIG. 5 is a circuit diagram showing a fourth embodiment of the discharge lamp lighting device of this invention, and FIG. 6 is a circuit diagram showing a fifth embodiment of the discharge lamp lighting device of this invention. FIG. 7 is a circuit diagram showing only the parts different from FIG. 2, and FIG. 7 is a block diagram showing a sixth embodiment of the discharge lamp lighting device of this invention. 1...DC power supply, 3a, 3b...Transistor, 4...Inductor, 5...Oscillation transformer, 6
a, 6b, 11, 13, 19...Resistor, 8...Discharge lamp, 8a, 8b...Electrode, 10...Switch device, 12...Timer circuit, 14, 16, 18, 2
1, 23... Capacitor, 15... Constant voltage diode, 20... Trigger element, A... Transistor inverter. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims for Utility Model Registration] (1) A transistor inverter having preheating means for converting power from a DC power source into AC power to light a discharge lamp and preheating electrodes of the discharge lamp;
This transistor inverter includes a timer circuit that outputs an output after a predetermined time when the DC power source is turned on, and is provided between the DC power source and the transistor inverter, and is in a cut-off state until the timer circuit outputs an output, and is conductive at the output of the timer circuit. a switch device for supplying the voltage of the DC power source to the transistor inverter; when the switch device is cut off, the voltage of the DC power source is divided and applied to the transistor inverter to cause the preheating means to preheat the electrodes of the discharge lamp; A discharge lamp lighting device comprising: voltage dividing means that is short-circuited by the switch device when the switch device is turned on; and continuity holding means that maintains the conduction state of the switch device. (2) The discharge lamp lighting device according to claim 1, wherein the oscillation transformer in the transistor inverter constitutes a leakage transformer, and its leakage inductance sets the current of the discharge lamp to a predetermined value. (3) The timer circuit is characterized by comprising a capacitor that charges the voltage of the DC power supply at a predetermined time constant, and a constant voltage diode that becomes conductive and outputs an output to the switch device when the charging voltage of this capacitor reaches a predetermined value. A discharge lamp lighting device according to claim 1 of the utility model registration claim. (4) The discharge lamp lighting device according to claim 3, wherein the constant voltage diode is replaced with a trigger element. (5) The discharge lamp lighting device according to claim 3, wherein the DC voltage supplied to the timer circuit is a pulsating DC voltage obtained by full-wave rectification from an AC power source. (6) The discharge lamp lighting device according to claim 3, wherein the DC voltage applied to the timer circuit is supplied by rectifying the output of an auxiliary winding provided in an oscillation transformer of a transistor inverter. . (7) The discharge lamp according to claim 1, wherein the preheating means is constructed by connecting a filament winding provided in an oscillation transformer of a transistor inverter to an electrode of a discharge lamp lighting device. lighting device. (8) The preheating means consists of a filament winding of an oscillation transformer of a transistor inverter, a transformer in which the primary winding is connected to the secondary winding of this oscillation transformer, and the secondary winding is connected in series with the filament winding. A discharge lamp lighting device according to claim 1, which is characterized by: (9) The discharge lamp lighting device according to any one of claims 1 to 8, wherein the switch device uses a transistor. (10) The discharge lamp lighting device according to any one of claims 1 to 8, wherein the switch device uses a thyristor. (11) The discharge lamp lighting device according to claim 1, wherein the transistor inverter is a push-pull type transistor inverter. (12) The discharge lamp lighting device according to any one of claims 1 to 11, which is characterized by having a capacitor in parallel with the transistor inverter and in series with the voltage dividing means.