JPS6151399B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a so-called two-lamp series sequential start type lighting device for hot cathode discharge lamps, which suppresses consumption of filament heating power by opening the filament heating circuit during lighting. Regarding.

In conventional quick-start type discharge lamp lighting devices, current flows through the filament heating circuit even while the discharge lamp is lit, so unnecessary filament heating power is consumed during lighting (for example, in a 40W fluorescent lamp). In this case, the power consumption of one-sided filament is about 1W).

Therefore, by opening the filament heating circuit during lighting, the filament heating power is suppressed.
It is possible to save power. For this purpose, it is conceivable to utilize changes in the voltage across the discharge lamp before and after lighting. This idea is effective in a single lamp lighting device. However, in the case of a so-called sequential start type discharge lamp lighting device in which two lamps are connected in series, the difference between the secondary no-load voltage of the ballast and the voltage of the two lamps is generally set small, so the above-mentioned idea does not apply. cannot be applied. Therefore, it has conventionally been thought that it is not possible to save power by opening the filament heating circuit with high reliability in sequential start type discharge lamp lighting devices.

The present invention provides the above-mentioned two-lamp series lighting device,
This was developed to eliminate the above-mentioned drawbacks, and the purpose is to reliably open the filament heating circuit after lighting the discharge lamp, thereby eliminating unnecessary power consumption.

The present invention provides a voltage detection device for opening the filament heating circuit in parallel with a discharge lamp connected in series with a high impedance element for starting, and a switching device for controlling the filament heating circuit. The present invention is characterized in that the switching device is made to respond to the voltage detection device.

Hereinafter, details of the present invention will be explained with reference to the drawings. FIG. 1 shows the basic configuration of the present invention.
Hot cathode discharge lamps 3 and 4 are connected in series between an AC power source 1 via a current limiting device 2, and a high impedance element 5 for starting is connected in parallel to one of the discharge lamps 3. Also, the other discharge lamp 4
A voltage detection device 6 is connected in parallel to the two. A switching device 7 responsive to this voltage detection device 6 is provided,
This switching device 7 is inserted into a filament heating circuit 8 for heating the filaments of the discharge lamps 3 and 4. The impedance of the voltage detection device is set to a value higher than that of the high impedance element 5.

In the above configuration, when the AC power supply 1 is connected, most of the power supply voltage is applied to the discharge lamp 4 and the voltage detection device 6 via the high impedance element 5, and the switching device 7 connected to the output end of the power supply voltage is applied to the discharge lamp 4 and the voltage detection device 6. In response, conduction occurs, the filament heating circuit 8 is closed, and the discharge lamp 3,
4 filaments are heated. When the filament is heated, the discharge lamp 4 begins to discharge slightly, and this slight discharge current generates a considerable high voltage across the high impedance element 5.
The discharge lamp 3 connected in parallel with the discharge lamp 3 also generates a slight discharge, causing the discharge lamps 3 and 4 to light up. After lighting, the current limiting device 2 acts to continue stable lighting. When the discharge lamp 4 lights up, the voltage applied to the voltage detection device connected in parallel with it decreases, so the voltage applied to the switching device 7 also decreases, its conduction stops, the filament heating circuit 8 opens, and the AC power source 1 The operating power of the discharge lamps 3 and 4 is cut off, and the power supply to the filaments of the discharge lamps 3 and 4 is cut off.

In the above description, the AC power supply 1 applied to the filament heating circuit 8 is turned off, but a switching device 7 may be provided to open and close the conductive wires 9, 9 connected to the filament individually or all at once. Further, as the switching device 7, any device that becomes conductive at a voltage higher than the set voltage and becomes non-conductive at a voltage lower than that, such as a combination of a two-terminal thyristor and a three-terminal thyristor, can be used.

Next, examples of the present invention will be described. Figure 2 shows one embodiment. In the figure, 10 is a leakage transformer that also serves as a voltage booster and a current limiter. The AC power supply 1 is connected to its primary winding, and a capacitor 11 and a safety discharge resistor are connected to the secondary side. 3 discharge lamps through 12 parallel circuits
and 4 are connected in series. 5 is discharge lamp 3
A capacitor 7 as a high impedance element connected in parallel with the switching device is composed of a bidirectional three-terminal thyristor 7a as a thyristor and a bidirectional trigger diode 7b as a thyristor. 8 is a filament heating circuit that heats the filaments of the discharge lamps 3 and 4, and the primary winding of the filament transformer 13 is a bidirectional three-terminal thyristor 7.
a to the primary winding of the leakage transformer, and the secondary windings are connected to the filaments of the discharge lamps 3, 4, respectively. The voltage detection device 6 consists of a series circuit of a resistor 14 and a capacitor 15. One end of the resistor 14 is connected to one end of the filament connected in common to the discharge lamps 3 and 4, and one end of the capacitor 15 is connected to the other filament of the discharge lamp 4. The connecting point between the resistor 14 and the capacitor 15 is used as the output terminal of the voltage detection device, and this output terminal is connected to the gate of the bidirectional three-terminal thyristor 7a via the bidirectional trigger diode 7b. .

Next, the operation will be explained. When the AC power supply 1 is turned on, a no-load voltage is generated on the secondary side of the leakage transformer 10, and most of this voltage is transmitted to the discharge lamp 4 and the voltage detection device 6 through the capacitor 5, which is a high impedance element. join. Therefore, a voltage sufficient to break over the bidirectional trigger diode 7 is applied to the capacitor 15 of the detection device 6, the diode 7b becomes conductive, and a voltage is applied to the gate of the bidirectional three-terminal thyristor 7a. The thyristor 7a becomes conductive and the filament heating circuit 8
is closed, and the filaments of the discharge lamps 3 and 4 are heated. As a result, sufficient voltage is applied to the discharge lamp 4 for starting, so a slight discharge begins, and this slight discharge current increases the voltage of the capacitor 5, which is a high impedance element, and the discharge lamp The electric lamp 3 also begins to generate a slight discharge, and the two discharge lamps 3 and 4 are turned on. When the discharge lamps 3 and 4 are turned on, the voltage across the discharge lamp 4 is considerably lower than the secondary no-load voltage of the leakage transformer 10, so the voltage across the capacitor 15 of the detection device 6 is determined by the bidirectional trigger diode. 7, the diode 7b stops conducting, the bidirectional 3-terminal thyristor 7a also stops conducting, and the filament heating circuit 8 is opened, so that no filament heating power is consumed. .

FIG. 3 shows another embodiment of the present invention, in which the same parts as in FIG. 2 are given the same reference numerals. 16 and 17 are filament heating circuits; the filament heating circuit 16 heats the commonly connected filaments of the discharge lamps 3 and 4;
It consists of a secondary winding 18 attached to the bidirectional 3
The filament heating circuit 17 is connected to the filament via the terminal thyristor 19, and the filament heating circuit 17 is connected to the discharge lamps 3, 4.
These filaments are connected to the secondary side of the transformer 10 via a capacitor 11 and a bidirectional three-terminal thyristor 20 in series. 21 is a voltage detection device, which includes a capacitor 22, a resistor 23, and a capacitor 24.
are connected in parallel to the discharge lamp 4 such that one end of the capacitor 22 is connected to a commonly connected filament. 25 is a switching device consisting of a bidirectional three-terminal thyristor 19 and a bidirectional trigger diode 26;
9 through a bidirectional trigger diode 26. 27 is a switching device consisting of a bidirectional 3-terminal thyristor 20 and a bidirectional trigger diode 28; Connect.

With the above configuration, when the AC power supply 1 is turned on, the capacitors 22 and 24 are charged, the bidirectional trigger diodes 26 and 28 are made conductive, and therefore the bidirectional three-terminal thyristors 19 and 20 are made conductive. The commonly connected filaments of the discharge lamps 3 and 4 are heated by the secondary winding 18, and the filaments on the power supply side are heated by the secondary short-circuit current of the transformer 10. The current flowing through the bidirectional three-terminal thyristor 20 becomes zero, and the bidirectional three-terminal thyristor 20
The discharge lamp 3,
Since the secondary no-load voltage of the leakage transformer 10 is applied to the discharge lamp 4, the discharge lamps 3 and 4 are lit after going through the above-described slight discharge and lighting process. After lighting, the voltage applied to the bidirectional trigger diodes 26 and 28 does not reach the breakover voltage, so the bidirectional three-terminal thyristors 19 and 20 do not conduct, the discharge lamps 3 and 4 stably light, and the filament is heated. The circuits 16 and 17 are opened and no current flows.

In the embodiments shown in FIGS. 2 and 3, the capacitor 11 is used as a fast-phase lighting type, but the capacitor 11 and the resistor 12 may be removed to provide a slow-phase lighting type. Further, although the leakage transformer 10 or 10' and the capacitor 11 are used as the current limiting device, a reactor, a capacitor, a resistor, or the like may be used. Further, as the voltage detecting device, other than those shown in the embodiments, ordinary ones can be used. The switching device is also optional; for example, a reverse blocking thyristor can be used instead of a bidirectional thyristor.

As described in detail above, the present invention provides a lighting device in which two discharge lamps each having a high impedance element for starting are connected in series, in which the above discharge lamp is connected in parallel with the high impedance element for starting. A voltage detection device formed with a high impedance value than a high impedance element is provided, and a switch device controlled by the detection device opens and closes the filament heating circuit, so unnecessary filament heating power is consumed while the light is on. Never. In addition, since there is a large difference between the secondary no-load voltage and the voltage between the filament of a lit discharge lamp, even if there are slight variations in the characteristics of the switching device, it will not malfunction and will be reliable and stable. I can do it,
Moreover, an economical discharge lamp lighting device can be provided.

[Brief explanation of the drawing]

The drawings relate to the present invention; FIG. 1 is a basic circuit configuration diagram, FIG. 2 is a circuit diagram showing one embodiment, and FIG.
The figure is a circuit diagram showing another embodiment. 1... AC power supply, 2, 10, 10', 11...
Current limiting device, 3, 4... Discharge lamp, 5... High impedance element, 6, 21... Voltage detection device, 7, 1
6, 27...Switching device, 8, 16, 17
...Filament heating circuit.

Claims (1)

[Claims] 1. First and second discharge lamps connected in series to an AC power source via a current limiting device, a filament heating circuit for these discharge lamps, and connected in parallel to the first discharge lamp. a high impedance element, a voltage detection device formed to have a higher impedance value than the high impedance element and connected in parallel to the second discharge lamp, and a switching device that controls the filament heating circuit in response to the voltage detection device. A discharge lamp lighting device characterized by comprising: 2. The switching device is characterized in that it includes a first thyristor inserted into the filament heating circuit, and a second thyristor that controls the first thyristor in response to the voltage detection device. A discharge lamp lighting device according to claim 1. 3. The discharge lamp lighting device according to claim 1 or 2, wherein the voltage detection device is composed of a resistor and a capacitor connected in series, and a connection point thereof is an output terminal. 4. The filament heating circuit includes a filament transformer including a primary winding energized by an AC power source and a plurality of secondary windings connected to heat each filament of each discharge lamp. 4. The discharge lamp lighting device according to claim 1, wherein the switching device is connected to control the primary winding. 5 The filament heating circuit includes a first heating circuit formed by connecting each power source side filament of each discharge lamp in series between the AC power source via the current limiting device, and a first heating circuit formed by connecting each power source side filament of each discharge lamp in series between the AC power source and a second heating circuit connected to the common connection filament, the switching device
A discharge lamp lighting device according to any one of claims 1 to 3, characterized in that the discharge lamp lighting device comprises two switching elements that separately control the heating circuits of the discharge lamp lighting device.