JPS6132997A - 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] [Technical field to which the invention pertains] The present invention relates to an improvement of a discharge lamp lighting device using a DC-AC converter, and in particular to an improvement of a discharge lamp lighting device using a DC-AC converter. Related to electric light lighting devices.

[Prior art and its problems]

Conventionally, as a discharge lamp lighting device using a DC-AC converter, one having a circuit configuration as shown in FIG. 3, for example, is known.

The DC voltage supplied from the DC power supply 1 is converted into AC by the DC-AC converter 2, and a high frequency voltage is generated in each winding of the transformer 3. The secondary windings 5a, 5b and preheating windings 6, 7 of the transformer 30 are connected to the discharge lamp 4, and the discharge lamp 4 is supplied with high frequency power and turned on.

When the lamp starts, the semiconductor switching element 9 connected in series to the secondary windings 5 a and 5 b is non-conducting, so
Electric power is supplied only to the cathodes 4a and 4h to preheat the cathodes. After a certain period of time, the semiconductor switching element 9 is turned on by a signal from the timer circuit 8, and a high voltage is applied to the discharge lamp 4, so that the discharge lamp lights up. In such a lighting device, the discharge lamp is lit with high-frequency power, so the luminous efficiency of the discharge lamp is improved compared to when the discharge lamp is lit with normal commercial frequency power, and the input power is required to obtain the same level of light output as before. Since it requires less power, it is attracting attention from the viewpoint of power saving effect. In order to further improve this power saving effect, efforts have been made to further reduce power loss in each part of the device. For example, in such a lighting device, the DC-AC converter 2
By preheating the cathodes 4a and 4b of the discharge lamp 4, the discharge lamp 4 is heated.
However, after the discharge lamp 4 is started, it is necessary to minimize power loss in the preheating circuit, so filter circuits 10a and 10b are provided in the preheating circuit.
The fact that the oscillation frequency of the DC-AC converter 2 changes before and after starting the discharge lamp is used to attenuate the high-frequency power after starting the discharge lamp to reduce power loss in the preheating circuit. . Another method is to use a leakage type for the output transformer 3 of the DC-AC converter 2 to increase the output voltage and take advantage of the drop in secondary voltage that occurs when the discharge lamp starts. Efforts have also been made to reduce power loss in the preheating circuit. However, the method using a filter circuit has the drawback that in order to increase the attenuation of high-frequency power in the preheating circuit, the inductor and capacitor that constitute the filter circuit must be large, making the device large and expensive. Furthermore, depending on the type of lighting method (for example, in the case of a multiple lamp series lighting method), the method of using a leakage type output lance cannot be expected to be sufficiently effective because the difference in output voltage before and after starting the discharge lamp is not large. There was a drawback.

[Purpose of the invention]

The present invention has been made in view of the above points, and it is an object of the present invention to provide a discharge lamp lighting device that can reliably reduce the power loss of the cathode preheating circuit by a simple means without increasing the size and price of the device. That is.

[Structure and operation of the invention]

FIG. 1 shows an embodiment of the present invention. 1 is a DC power supply, and 2 is a DC-AC converter. The difference from the conventional example is that in addition to the series circuit of the transformer 30 secondary windings 5a, 5b and the semiconductor switching element 9, the preheating control transformer 100 primary windings and l
11 oa are inserted in series, at least two secondary windings 1gb and 10c are provided on the secondary side of the preheating control transformer 10, and one end of each is connected to the preheating windings 6 and 7 of the transformer 3. This is the point where the other end is connected to the cathodes 4a and 4b of the discharge lamp 4.

Note that the symbols attached to each winding of the preheating control transformer 10 indicate the winding start side, and do not necessarily have to be in the position shown in the diagram. The replaced diagram is shown in Figure 2.

When the power is turned on and DC voltage is supplied to the DC-AC converter, and a high frequency voltage is generated in each winding of the transformer 3, the switch 9 is open while no signal is received from the timer circuit (while the time is not up). So the second volume 1
Although a high frequency voltage is applied to i15a and i15b, it is not applied to the discharge lamp 4.

Preheating winding @ 6, 7K 1111, lll11 Figure f) < Secondary winding 10b, 1 of preheating control transformer 10
0e to each cathode 4m and 4b, preheating the cathode (
At this time, the preheating control transformer 10 for both ill and 1M2
Since the current flows from the winding start of the secondary windings 1ob and toe (ff is the winding end side) to the winding end side (or winding start side), the direction of magnetic flux generated in the transformer 10 is the same direction, so 1llll , cannot prevent the flow of 1i12. ).

During this period, current flows only through the cathodes 4a and 4b, and the main voltage is not applied to the discharge lamp, so even if the discharge lamp is likely to light up, it will not light up until the switch 9 is turned on.
The reliability of cathode preheating increases.

Then, when a signal is received from the timer circuit, the switch 9 is closed, so that a voltage sufficient to light the discharge lamp 4 is applied to the discharge lamp 4, and the discharge lamp 4 is turned on. When the discharge lamp 4 is turned on, a main current (lamp current) flows through the secondary winding of the transformer 30 through the primary winding a1oa of the preheating control transformer 100.

Now, assuming that IL, iHl,, 1m12 flows in the direction shown in Fig. 2, the current direction induced in the secondary windings 10b and 10c by iL flowing through the primary winding 10a is icl, and the amount C2 Because it is in the direction of icl #iH1,
By setting ic2#IH2, the preheating current is reduced.

〔Effect of the invention〕

As explained above, the present invention uses a DC-AC converter,
In a lighting device that generates a high frequency voltage in each winding of a transformer, a preheating control transformer is provided, its primary winding is inserted in series with the secondary winding of the transformer and a semiconductor switching element, and the secondary winding is connected to the preheating circuit. By inserting it in series with the semiconductor switching element, the cathode of the discharge lamp is sufficiently heated during the non-conducting period, and when the semiconductor switching element becomes conductive and the discharge lamp lights up and lamp current flows, the preheating current is blocked. , it is possible to reduce preheating power. In addition,
In the embodiment shown in FIG. 1, the semiconductor switching element 9 and the preheating control transformer 10 are connected to the second winding of the transformer 30 @ 5 a ,
5b, but it may be located between the secondary winding 1115m and the preheating winding 6 or between the secondary winding 115b and the preheating winding T.

Further, a semiconductor switching element 9 and a preheating control transformer 10
is adjacent to semiconductor switching element 9.
The secondary winding 5a or 5b1 may be aligned with I- of the preheating control transformer 10. In short, it suffices to locate it where the lamp current flows.

Although the switch 9 has been described as a semiconductor switching element such as a triac, it is not limited to this.

Although a specific circuit is not shown for the DC-AC converter, any type of converter that can convert direct current to alternating current may be used.

Further, although a specific circuit for the timer 8 is not shown, any device may be used as long as it outputs a signal that can make the semiconductor switching element conductive after a certain period of time after power is turned on.

The semiconductor switching elements may be replaced with relay contacts. Further, the DC power source may be a pulsating DC power source obtained by full-wave rectification of a commercial AC power source.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of one embodiment of a discharge lamp lighting device according to the present invention, FIG. 2 is a partial circuit diagram of another embodiment, and FIG. 3 is a circuit diagram of a conventional discharge lamp lighting device. In Figures 1 and 2, 1... DC power supply, 2...
・DC-AC converter, 3...Transformer, 4...Discharge lamp, 4m, 4b...Heat pole, 5a, 5b...Transformer secondary winding, 6,7...Preheating winding Line, 8... Timer circuit, 9... Switching element, 10... Preheating control transformer, 10a... Preheating control transformer primary winding %1
0b, 10C...Preheating control transformer secondary winding. ? /Figure 72 Figure 5

Claims (2)

[Claims] (1) A DC-AC converter that converts direct current to alternating current, and the D
It comprises a transformer for taking out the output of the C-AC converter, and a discharge lamp powered by the transformer, the transformer having a secondary winding and at least two preheating windings, and the transformer having a secondary winding and at least two preheating windings. In a discharge lamp lighting device in which a switching element that is non-conducting or open for a certain period of time at startup is inserted in series in the winding, a preheating control transformer is connected to a series circuit of the secondary winding of the transformer and the switching element. 1
A secondary winding is inserted, and the secondary winding of the preheating control transformer has at least two output windings, each of which is connected to one end of the preheating winding of the transformer and one end of the preheating electrode of the discharge lamp. A discharge lamp lighting device characterized by being connected. (2) The secondary winding of the preheating control transformer is wound so that the secondary voltage induced in the winding is in a direction that blocks the preheating current. Discharge lamp lighting device as described in .