JPS583598B2 - discharge lamp lighting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is an improvement in a discharge lamp lighting device in which a plurality of discharge lamps connected in parallel have a common starting circuit, and the starting circuit generates a kick voltage in a ballast section. Regarding.

Discharge lamp lighting devices are known that have a common starting circuit for a plurality of discharge lamps in parallel relationship.

However, known devices of this type are constructed such that the starting device operates normally when all the discharge lamps are preheated and ready for lighting.

Therefore, if one of the lamps malfunctions, the other normal discharge lamps may not turn on, or even if they do, their lifespan may be shortened.

Furthermore, from the perspective of power saving, even in multi-light lighting equipment, it may be required to remove some of the discharge lamps from the equipment in advance and turn on the remaining discharge lamps for illumination.
Conventional devices of this type cannot meet these requirements.

The present invention has been made in order to eliminate the drawbacks of the conventional devices described above, and it is possible to start all the discharge lamps even if the starting of a plurality of discharge lamps is uneven, and also allows some of the discharge lamps to be disconnected. It is an object of the present invention to provide a discharge lamp lighting device that can reliably start and light a remaining discharge lamp even if the remaining discharge lamp becomes malfunctioning or is removed.

The present invention is characterized in that a starting device acts in common on a plurality of discharge lamps arranged in parallel, but the starting device operates in connection with a single discharge lamp selected in advance. It is.

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

For example, two discharge lamps 11 and 12 connected in series with ballasts 21 and 22, respectively? It is connected in parallel between the AC power sources 3 through the AC power source 3.

The stabilizers 21 and 22 include inductance,
For example, a choke coil.

The non-power supply side terminals of both electrodes of each discharge lamp 1, 12 are collectively connected, and a common starting device 4 is connected between them.

That is, when viewed from each of the discharge lamps 11 and 12, the starting device 4 is inserted in series into the preheating circuit of each discharge lamp.

Note that means for preventing interference between the discharge lamps 11 and 1 may be adopted as necessary, but for example, diodes 5 and 52 may be inserted in series in a preheating circuit portion unique to each discharge lamp. Ru.

Is this the known type of equipment? However, according to the invention, the starting device 4 is configured to be responsive to the power supply voltage and a preheating current flowing to a preselected single discharge lamp, e.g. 11.

That is, the starting device 4 includes a switching element 6, for example, a first cyrisk, and a switching element 6, which conducts in accordance with the voltage value of the AC power source 3 and passes a preheating current for each of the discharge lamps 1, 1. A control element 10 that becomes conductive when the preheating current of a single discharge lamp (discharge lamp 11 in this embodiment) selected in advance among the discharge lamps 1 reaches a predetermined value; Is it applied to switching element 6? Capacitor 7 that forcibly makes 6 non-conductive
It includes the following.

When the switching element 6 is rendered non-conductive by the capacitor 7, a kick voltage is generated in the inductance of each of the ballasts 2, 2.

Furthermore, to explain the starting device 4 in this embodiment in detail, the starting device 4 includes a trigger circuit 8 that conducts the switching element 6 according to the power supply voltage, and a trigger circuit 8 that is inserted into the preheating circuit of the selected discharge lamp 11. When the voltage across the current detection impedance element 9 reaches a predetermined value, the current detection impedance element 9 becomes conductive and the capacitor 7
The second thyristor serves as the control element 10 for applying a charging charge to the switching element 6, a diode 11 for charging the capacitor 7, and a resistor 12.

Note that the switching element 6 may be any one of SCR, TRIAC, SSS, etc., and the means for making the switching element 6 conductive according to the power supply voltage can also be modified as appropriate.

Further, the means for detecting the preheating current of the selected discharge lamp can also be constructed using a known current transformer.

Furthermore, in addition to this embodiment, the capacitor 7 may be charged from the power supply side of the discharge lamp, and the control element 10 that applies the charge of the capacitor 7 to the switching element 6 may be configured in other ways, such as by using a transistor. It is easy to understand that this can be the case.

Next, the operation of this embodiment will be explained with reference to the voltage and current waveform diagrams in FIG.

When the power is turned on, a power supply voltage is applied to the trigger circuit 8, so when the power supply has a forward polarity with respect to the switching element 6, a trigger current flows into the gate of the switching element 6, and at time t1 in Fig. 2a. Switching element 6 becomes conductive.

Note that FIG. 2a shows the terminal voltage of the switching element 6, the second
FIG. 2B shows the power supply voltage, FIG. 2C shows the preheating current, and FIG. 2D shows the current of the switching element 6.

As a result, a preheating current flows from the AC power source 3 through both electrodes of each discharge lamp 11, 12 and the switching element 6, and each electrode begins to be heated.

The preheating current of the discharge lamp 11 is determined by the current detection impedance element 9.
However, when the terminal voltage of the impedance element 9 reaches a predetermined value, the control element 1 is detected at time t2 in FIG.
0 is conductive.

Prior to this, the capacitor 7 is connected to the AC power supply in advance when the power supply has the opposite polarity to the switching element 6. Since the capacitor 7 is charged via the resistor 12 and the diode 11, when the control element 10 becomes conductive, the charged charge of the capacitor 7 is applied to the switching element 6 in the opposite direction via the control element 10.

Therefore, the switching element 6 is reverse biased and becomes non-conductive.

As a result, kick voltage vK is generated as described above.

In this embodiment, resonance between the capacitor 7 and the ballasts 2, 22 is added to this kick voltage vK.

That is, the current path passing through the ballast 2, capacitor 7, control element 10, and diode 5 and the current path passing through the ballast 22, capacitor 7, control element 10, current detection impedance 9, and diode 5 cause a resonance phenomenon. present.

The above operation is performed every half cycle of the power supply voltage, but
If a unidirectional switching element 6 is used, the above operation is performed once in a half cycle of forward polarity.

During the half cycle of the other polarity, no preheating takes place and the mains voltage is applied to the discharge lamp.

Therefore, by repeating the above operation, the discharge lamps 11, 1
When the above-mentioned kick voltage is applied after each of the electrodes 2 has been sufficiently heated by the flow of preheating current and has reached a sufficient thermionic state, each of the discharge lamps 11 and 12 lights up.

Note that before the discharge lamps 1, 12 are turned on, after the switching element 6 becomes non-conductive, the switching element 6 may remain non-conductive until the next half cycle or the next cycle, but the kick voltage It is also possible to conduct again immediately after this occurs.

That is, when the kick voltage vK has finished being generated, if the discharge lamps 1, 12 are not lit, the power supply voltage is still applied to the trigger circuit 8, and therefore, the trigger circuit 8 is activated at that instant. By making it sufficiently large, the switching element 6 can be made conductive again and a preheating current can flow.

This arrangement is advantageous for the purpose of increasing the preheating current sufficiently.

When the lamp is turned on, a lamp voltage is applied across the starting device 4, and since the lamp voltage is considerably lower than the power supply voltage, the switching element 6 is no longer conductive.

Note that if the discharge lamps 11 and 12 are not lit at the same time, the starting device 4 continues to operate, so that they can be lit at the same time.

In other words, release it now? If the lamp 11 is lit by applying a kick voltage and the other discharge lamp 12 is not lit, the switching element 6 becomes non-conductive, but the starting device 4
Since the voltage across the unlit discharge lamp 1, that is, the power supply voltage, is applied to the starting device 4, the switching element 6 of the starting device 4 operates again, and therefore the discharge lamp 11, which has been lit once, is also short-circuited and repeats the starting operation again. .

On the other hand, even if the other discharge lamp 1 is lit before the other discharge lamp 1 is lit, the switching element 6 does not maintain the non-conducting state, so both the discharge lamps 11 and 1 are forcibly preheated and the kick voltage is generated. continues, and eventually each discharge lamp 11,
12 are lit at the same time.

Of course, the above operation is the same even when there are three or more discharge lamps.

? a discharge lamp 1 for detecting a selected preheating current;
If a discharge lamp 1 other than the above becomes malfunctioning due to disconnection of its electrodes due to its lifespan, or if it is removed from the lighting equipment, the voltage across the discharge lamp that is malfunctioning or removed is applied to the starting device 4. It will be easily understood that the remaining discharge lamps operate perfectly normally since the discharge lamp does not.

In the above embodiment, the kick voltage is generated only in half waves of the AC power supply voltage, but it is also possible to generate the kick voltage in both waves of the AC power supply voltage.

In this case, for example, a pair of starting devices as shown in Figure 1 may be used, each with positive and negative polarity, or a bidirectional switching element may be used and a capacitor or the like may be used to forcibly make the switching element non-conductive. It is easily understood that it can be carried out appropriately by using a pair of means including one for positive and one for negative polarity, respectively.

As described in detail above, the present invention provides a switching element that conducts a common starting device for a plurality of discharge lamps installed in parallel in accordance with the power supply voltage and conducts a preheating current for each of the discharge lamps. , a control element that becomes conductive when the preheating current of a single discharge lamp selected in advance reaches a predetermined value; and a charging charge is applied to the switching element via the control element to switch the switch. Since the configuration includes a capacitor that forcibly makes the discharge lamp non-conductive, if the discharge lamps start unevenly, a reliable start can be obtained by restarting the starting device. If a discharge lamp other than the discharge lamp becomes malfunctioning due to disconnection of an electrode or is removed, the remaining discharge lamps can be reliably started.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing one embodiment of the present invention, and Fig. 2 is a circuit diagram showing an embodiment of the present invention.
FIG. 3 is a diagram of voltage and current waveforms at various parts of the illustrated circuit. 11, 12... Discharge lamp, 21, 2...
Ballast, 3... AC power supply, 4... Starting device, 6... Switching element, 7...
- Capacitor, 10... Control element.

Claims (1)

[Scope of Claims] 1. an AC power source; a plurality of discharge lamp circuits connected in parallel between the power sources, including a ballast having an inductance and a series portion of discharge lamps; a starting device whose power supply side terminals are respectively collectively connected and commonly connected between them; the starting device includes a switching element that conducts in response to a power supply voltage and allows a preheating current to flow through each of the discharge lamps; and a control element that becomes conductive when a preheating current of a single discharge lamp selected in advance among the plurality of discharge lamps reaches a predetermined value, and a charging charge is applied to the switching element via the control element. and a capacitor that forcibly turns off the switching element. 2. The starting device has a current detection impedance element inserted in series in a preheating circuit portion of the single discharge lamp, and conducts when a voltage appearing on the impedance element reaches a predetermined value to discharge the charge charged in the capacitor. 2. The discharge lamp lighting device according to claim 1, further comprising a thyristor as the control element for applying the voltage to the switching element.