JPS59158094A - Device for firing discharge lamp - 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 The present invention relates to a discharge lamp lighting device for lighting a plurality of discharge lamps having different rated currents, etc., and particularly to electrode preheating thereof.

2. Description of the Related Art Conventionally, there is a discharge lamp lighting device shown in FIG. 1 that lights a plurality of discharge lamps with different rated currents using one lighting device. In Fig. 1, 1 is an AC power supply, 2 is a lighting device energized by the power supply 1, 3 is a high-frequency power supply unit, 4 is a rectifier circuit that performs full-wave rectification, and 5 is DC power obtained by the rectifier circuit 4. 6 is an output transformer of the inverter 5, and is composed of a leakage transformer.

51 is a high frequency choke coil, 52a, 52bU) transistors, 53a and 53b are resistors, 54 is a resonance capacitor, 6a and 6b are collector windings, 6C is a feedback winding, 6
s is the secondary winding, 61 to 63 are the preheating windings, and the output transformer 6
It is installed on the secondary side of the

7 is a current balancing transformer (hereinafter referred to as a balancer) with an input tap 7C connected to one output end of the inverter 5;
7 a * 7 b are the first and second windings of the balancer 7, 8 is a discharge lamp connected in parallel to the balancer 7, 9 is a discharge lamp connected in series with the discharge lamp 8, and its rated current is the same as that of the discharge lamp 8.
Also, discharge lamp 9 is more common.

8a, 8b, 9a, 9b are preheating electrodes of the discharge lamps 8, 9;
Electrodes 8kl and 9a are connected in series to form a preheating winding 63.
connected to. Further, the electrodes 8a and 9b are each connected to a preheating winding 61.
．． 62. Reference numeral 10 is a starting circuit, which is composed of a timer circuit. 10a is a starting switch opened and closed by the starting circuit 10.

In the conventional device with the above configuration, when the AC power supply 1 is turned on, the transistor 52a is turned on in the inverter 5 by the action of the feedback winding 6c.

52b alternately opens and closes to generate a high frequency voltage in the output transformer 6. At this time, the resonance capacitor 54 forms a resonance circuit together with the inductance of the winding of the output transformer 6, and controls the entire output frequency of the inverter 5. Since the starting switch 10a is now open, no voltage is applied to the discharge lamps 8 and 9, and the discharge lamps 8 and 9 do not start. On the other hand, the voltage of each preheating winding 61 to 63 is equal to each preheating electrode 8a + 8b r
9a*9bK is applied to preheat the electrode. Thereafter, when the timer circuit of the starting circuit 10 times up, the starting switch 10a is short-circuited, and the high voltage generated at no load is applied to the secondary winding 6S, so that the discharge lamp 9 is first lit.

When the discharge lamp 9 starts, a current flows through the winding 7b, and the voltage generated in the winding 7b is boosted by the balancer 7 and applied to the discharge lamp 8. Since the voltage generated in the paralleler 7 can easily exceed the voltage generated in the secondary winding 6S, the discharge lamp 8 is also started.

In this way, the discharge lamps 8 and 9 are lit, the output current set to the rated value by the output transformer 6 flows through the discharge lamp 9, and the output current is inversely proportional to the turns ratio of the windings 7a and 7b. A current flows through the winding 7a, and this current is set to a rated value.

Generally, when the rated current is different like discharge lamps 8 and 9,
Since each electrode is designed to withstand the discharge current, the resistance value of the electrode is low in a discharge lamp with a large rated current. *9 The resistance value of b is smaller. Therefore, the preheating current required to reach the optimum electrode temperature is different, and the lower the resistance value, the more the preheating current is required. In addition, during preheating when the start switch 10a is open, the electrode 8b
.

Since electrodes 9a are connected in series and preheated by the voltage of the winding 63, most of the heat generated by the preheating current occurs in the electrode 8b, which has a high resistance value, resulting in a high temperature. If this preheating current is set by the voltage generated by the winding 63 so that the electrode 8b has the optimum temperature, the temperature of the electrode 9a will be lower than the optimum temperature, and an increase in starting voltage and early blackening will likely occur. Further, if the preheating current is set so that the electrode 9a has an optimum temperature, the electrode 8b has a drawback that the temperature becomes excessive and the wire is easily broken.

The present invention was made in order to eliminate the above-mentioned drawbacks of the conventional method, and it is possible to reduce the preheating current by connecting an impedance in parallel to the electrodes of a discharge lamp whose rated current is small, that is, the resistance value of the electrodes is high. It is an object of the present invention to provide a discharge lamp lighting device that can set the optimum value.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 shows a first embodiment of the present invention, and 11 is an electrode 8b.
The other configuration is the same as that in FIG. 1 except for the preheating current correction impedance connected in parallel with the preheating current correction impedance.

In the above configuration, when the AC power supply 1 is turned on, a high frequency voltage is generated in each winding 6s, 61 to 63 of the output transformer 6, as in the conventional case. During preheating when the starting switch 10a is open, each electrode 8a, 8b.

9a and 9b are preheated by the voltage generated in the preheating windings 61 to 63. In particular, the series-connected electrodes 8 b p 9 a are preheated by the voltage of the winding 63 . The voltage of the winding 63 at this time is set so that a preheating current flows such that the temperature of the electrode 9a of the discharge lamp 9, which has a large rated current and a low resistance value of the electrodes 9a and 9b, reaches an optimum value.

On the other hand, the preheating current of the electrode 8b of the discharge lamp 8, which has a small rated current and a low resistance value of the electrodes 8a * 8b, is smaller than the preheating current of the electrode 9a because a part of the current is shunted to the impedance 11. According to the setting value of υ electrode 8
Both b*9a can be set to the optimal preheating current, and the temperature will also be at the optimal value. Next, when the starting switch 10a is short-circuited, the discharge lamp 8.9 lights up. Even during this lighting, the current flowing through the electrode 8b is shunted by the impedance 11, and the preheating current of the electrodes 8b and 9a becomes an optimum value.

In this way, the preheating current flowing to the electrode 9a is adjusted by the voltage of the winding 63, and the preheating current h flowing to the electrode 8b is adjusted by the impedance 11, so that the preheating current is optimal for each.
, the temperatures of the electrodes 8b and 9a can also be set to optimum values.

FIG. 3 shows a second embodiment of the present invention, in which discharge lamps 8.9 having different rated currents are connected in parallel via a balancer 7, and electrodes 8b t9a are connected in parallel. Further, the impedance 11 is connected in series to the electrode 9a.

During preheating when the start switch 10a is open, each electrode 8
a r 8 b, 9 a * 9 b is the preheating winding 6
It is preheated with a voltage of 1 to 63. The electrode 8b is connected in parallel with the series circuit of the electrode 9a and the impedance 11, and the winding 6
3 voltages are applied. The voltage of the winding 63 is set so that the preheating current flowing through the electrode 8b having a high resistance value is set to an optimum value, and the preheating current flowing through the electrode 9a is adjusted by the impedance 11 by this voltage to the optimum value. can. Thereafter, when the starting switch loa is short-circuited, the discharge lamps 8 and 9 are turned on, and the winding 7a of the balancer 7 is turned on.

Each lamp is lit according to its rated current by a current inversely proportional to the turns ratio of 7b.

In the above embodiment, when the discharge lamps 8 and 9 were lit in series, the electrodes 8b and 9a were connected in series, and when the discharge lamps 8 and 9 were lit in parallel, the electrodes 8b and 9a'i were connected in parallel. There is no particular relationship between the connection of the lamp 8.9 and the connection of the electrodes 8b and 9a. Although the discharge lamps 8 and 9 have different rated currents, the present invention is effective as long as the electrodes have different resistance values. Furthermore, in order to light up the discharge lamps 8 and 9 having different rated currents at rated currents, an impedance may be connected in parallel with the discharge lamp 8 having a lower rated current than in the embodiment. Furthermore, when a plurality of taps 7c of the balancer 7 are provided and dimming is performed by switching these, when dimming is performed by connecting an impedance in series with the tap 7c, and between the AC power source 1 and the high frequency power supply device 3. The present invention can also be applied to cases where a phase control circuit is provided to perform dimming. In addition, the preheating power source is not limited to the preheating windings 61 to 63,
Each electrode 8a.

Any material that can supply preheating current to 8b, 9a, and 9b may be used. Further, the number of electrodes may be three or more. The inverter 5 may also be of any type as long as it can light a plurality of discharge lamps having different rated currents. The impedance 11 may be anything as long as it can limit the preheating current, and may be an M resistor, a capacitor, an inductance, or a thermistor or posostar whose impedance changes due to self-heating caused by the preheating current.

As described above, in the present invention, one preheating electrode of each discharge lamp is connected in series or in parallel to a common preheating power source, and when the preheating electrodes are connected in series, they are connected in parallel to the preheating electrode with a high Ktii resistance value. If the preheating electrodes are connected in parallel, the impedance can be connected in series with the preheating electrode with a low resistance value. In either case, the optimal preheating current can be supplied to each electrode. This allows the temperature of each electrode to be optimized. Therefore, an increase in starting voltage, early occurrence of blackening, wire breakage, etc. can be suppressed.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a conventional device, and FIGS. 2 and 3 are block diagrams of first and second embodiments of the device of the present invention, respectively. DESCRIPTION OF SYMBOLS 1... AC power supply, 2... Lighting device, 3... High frequency power supply device, 5... Inverter, 6... Output transformer, 6s°°゛Secondary winding, 61-63... Preheating winding, 8
,9...Discharge lamp, 8a, 8b, 9a
, 9 b - preheating electrode, 11... impedance for preheating current correction. Note that the same reference numerals in the figures indicate the same or corresponding parts. Agent Shin Kuzuno −

Claims (1)

[Claims] (1) In a discharge lamp lighting device that lights multiple discharge lamps with different resistance values of preheating electrodes using a high-frequency power source, one preheating electrode tl of each discharge lamp is connected in series or parallel and preheated from a common preheating power source. When one preheating electrode is connected in series, a preheating current correction impedance is connected in parallel with the preheating electrode with a high resistance value, and when one preheating electrode is connected in parallel, a resistor A discharge lamp lighting device characterized in that a preheating current correction impedance is connected in series with a preheating electrode having a low value.