JPS58169899A - 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 device that uses an inverter to convert power from a DC power source into high frequency power and applies the power to a discharge lamp such as a fluorescent lamp to light it.

Devices that use inverters to convert DC power into high-frequency waves of several KH2 or higher to light discharge lamps such as fluorescent lamps are more difficult to use than the so-called choke coil type ballasts that include reactors that have been commonly used in the past. It has become popular in recent years due to its advantages such as low loss and light weight.

By the way, when using an inverter to light a discharge lamp, the output voltage of the inverter must be set high enough to ensure that the discharge lamp can be lit even under adverse conditions such as low temperatures, so please do the following: The phenomenon was easy to understand.

In other words, when starting a discharge lamp, a high voltage was applied to both ends of the discharge lamp at the same time as the electrodes began to heat up. For this reason, a so-called cold start, in which discharge is forcibly started before the electrode has been preheated, is likely to occur, which may result in sudden damage to the electrode.

In order to prevent this cold start, it is sufficient to preheat the electrodes before starting discharge, and an inverter is needed to preheat the electrodes.

There is also a conventionally known method in which an inverter is provided separately from the inverter that lights the discharge lamp, and the inverter is first operated for preheating, and then the inverter that lights the discharge lamp is operated to start discharging.

However, this type of device has the disadvantage that it becomes expensive because it requires separate inverters for preheating the electrodes and inverters for lighting the discharge lamp.

This invention aims to eliminate the above-mentioned drawbacks, and provides a device that can preheat the electrodes and then start discharging from the discharge lamp without using an inverter exclusively for preheating the electrodes. .

The details of this invention will be explained below with reference to one illustrated embodiment. Figure 1, Figure 2. Third. 4th. 5 and 1 are explanatory diagrams of the operation of the present invention, and FIG. 6 and FIG. S are diagrams showing an embodiment of the present invention.

In Figure S? , (tl is a commercial frequency AC power supply.

(2) is a switch 13) which is a full-wave rectifier, and (m) is a self-excited push-pull type transistor inverter equipped with an inverter (in this case, an output transformer φ). (B) is a control device for controlling the operation of this inverter, and includes the above-mentioned switch (a timer device tc which generates a nine signal at a predetermined time after turning on the switch 21).

(6) is a discharge lamp, and (6a) and (6b) are electrodes.

Note that the inverter (A) is composed of transistors (k), (3
b).

Collector volume! I (5N), pace feedback winding (SB)
, filament winding (5F), output transformer (5) consisting of secondary winding g (5B), collector winding 1i (
5N) and the output side of the full-wave rectifier (3), and the transistor (5a).
, (!11)) pace resistance (6a) , (6b)
, a capacitor (5C) connected in parallel with the collector winding (5N), and a resonant circuit of one cage inductance which is equivalently connected in series with the secondary winding (5N).

The control device (B) also controls a full-wave rectifier (8) that rectifies the output of the AC power source (11K-connected transformer (7), this transformer ()) via the switch (2), Diode (9) connected to the output terminal of (8)
) and capacitor, resistor aυ and constant voltage diode ring,
Resistor (2), transistor Q41, αe, diode 4, and the resistor (91° capacitor (up), diode A, and constant voltage diode member forming the timer device (C).

Next, detailed operation will be explained. First switch (2)
is closed and AC power (1) is supplied.

A voltage as shown in Fig. 1 (7) is applied to the inverter (Al) via the full-wave rectifier +31. At the same time, a predetermined voltage is also generated in the transformer (7) K of the control device (I), and the full-wave rectifier (8) also supplies a full-wave rectified pulsating DC voltage. During a period when the instantaneous value of the voltage of the AC power supply (1) is low, the retransistor a-
turns off, supplies a base current to the transistor aeK through the diode QcJ, turns on the transistor αG, and supplies current to the resistors (M) and (Sb) of the inverter (M).

Therefore, the transistor (3a) of the bow inverter (mu).

(3b) The base current begins to flow in K, and the base feedback winding (
5B), the inverter (A) performs a self-oscillation operation as is well known, and an output voltage is generated in each winding of the output transformer (5).

As a result, the electrode (6a) * (61
)) + will be preheated. FIG. 1 shows this situation, and FIG. 1 (a) shows how the transistor I is turned on by the Zener voltage of the constant voltage diode a, and vR1?
In the above case, the inverter stops outputting, and if it is lower than this, the inverter generates an output during the period from 01 to θ2.

(1) is the period during which the inverter stops outputting T! occurs and shows T1 for one period.

The period of each half cycle of the AC power supply (1) is indicated by ding.

Also, ) indicates the preheating voltage applied to the electrodes (da) and (Sb) K, that is, the output voltage of the filament winding (5F) of the output transformer G). At this time, the period T2-1 during which the inverter stops outputting. It is clear that it can be set by the output voltage of the full-wave rectifier (8) and the Zener voltage of the constant voltage diode α2. After this,
When the terminal voltage of the capacitor (1) of the timer device (C) rises and exceeds the Zener voltage of the constant voltage diode Q8, the transistor αG is connected to the resistor 1 through the diode (Iη).
Since the base current is continuously supplied from 1'J, it continues to conduct continuously. Therefore, the inverter (A) does not have a period T2 during which the output is stopped, and the discharge lamp is lit because the inverter (A) continuously generates the output. Now, as a result of a detailed study regarding the period T1 during which the inverter generates an output at the time of startup and the period T2 during which the inverter is stopped, the following facts were found.

FIG. 2, FIG. 3, FIG. 4, FIG. 5, and FIG. 1 are diagrams for explaining the operation of the apparatus of the present invention.

Figure 2 shows the filament winding i1 of the device as shown in Figure 6.
(51') output voltage V, and the output voltage Vz of the secondary winding (5S) when the discharge lamp has not started discharging yet (
This is approximately the same as the secondary no-load voltage of the inverter), but as shown in Figure 1 (2) and 2), it changes when the period Tt during which the output of the inverter (A) is generated is changed. shows. Here, T corresponds to the period of each half cycle of the AC power supply (11).

Figure 3 shows how the starting voltage of a typical rapid-start fluorescent lamp, which is a discharge lamp with a preheating FIL pole, changes depending on the preheating voltage used to preheat the pole.
If the preheating voltage is above a predetermined value (■EPo in the figure), the starting voltage Vs is a certain value vs.

This shows that even if the preheating voltage is increased beyond this point, the starting voltage will hardly decrease. It is assumed that the conduction period ratio that produces VFo corresponds to X2 in FIG.

Next, Figure 4 shows how the voltage that causes a cold start in a discharge lamp changes with respect to the conduction period ratio K (same as in Figure 2), and how the cold start voltage increases as the conduction period ratio decreases. show. Therefore, now the output voltage of the secondary winding (5B) of the inverter (abbreviated as secondary no-load voltage -*)
If the conduction period ratio is 100%, even if the discharge lamp is set to cold start, the conduction period ratio is xl.
When it is made smaller, the cold start voltage cI
I can't reach K.

From the above explanation, when the device of this invention is constructed and started,
■: Output voltage v2 that prevents the discharge lamp from cold starting
In other words, select a pressure with no secondary load. ■: The electrode is sufficiently preheated and a preheating voltage is applied to reduce electrode damage. It is desirable to set so that the above conditions (1) and (2) are satisfied at the same time.

FIG. 5 shows this situation in an easy-to-understand manner. Here, the one corresponding to the conduction period ratio X is the secondary winding edge (5B)
Since the output voltage (2) corresponds to the cold start voltage VO, it may be set smaller than xl.

In addition, mx2 is the conduction period ratio at which the preheating voltage applied to the electrode from the filament winding (5F) becomes vFo in Figure 3, and it is optimal to set the conduction period ratio between ex2 and xl at the time of startup. It can be seen that it is. However, sx2 is vFo
There were cases where it was acceptable even if it was slightly lower.

Kono X2 to X1'! , ear bar 11) Secondary winding m1 (5B) and filament winding? Although there is a slight difference depending on the output voltage setting value of tM (5F), the secondary winding (
SS), it is economically disadvantageous to make the output voltage extremely high, and generally the secondary winding output voltage E corresponding to the conduction period ratio of x2 a xl is 1.0% of the conduction period ratio.
17), the output voltage YiC is 0.2Y(IC(0,
Setting it to 8M was good.

In addition, from the viewpoint of preventing cold starts, it is useful to set the period during which the output is stopped at startup so that it always includes the period in which the voltage value of the input DC voltage of the inverter is at least the peak value (L8). .

Furthermore, the period during which inverter output is generated at startup is as follows:
It is easier to supply pace current while the inverter is operating, especially if it is provided continuously, especially across the phase θ0 where the instantaneous value of the DC voltage is the minimum, as shown in Figure 1 (2). It is.

Based on this invention for a long time. Still other examples will be shown. FIG. 1(3) shows the operation of such a device.

Figure 1 (3) shows the period T1 during which the inverter generates an output.
Of these, e ”n (01 to θ0 in the figure) and T12 (0 in the figure
0 to θ2) are different, and T11 is longer.

FIG. 8 shows an embodiment of the apparatus according to the present invention that performs such an operation, and FIG. 7 is a diagram for explaining the operation.

In FIG. 8, (B) is a control device, and the parts not shown are constructed in the same way as the device in FIG. S.

In the figure, all is a synchronous circuit that generates a signal every half cycle of the AC power supply (11), and @ is a delay circuit that generates a signal for a predetermined period after a certain time td from the signal generated by the synchronous circuit Q11. It is composed of a combination of monostable multivibrators. (2) is a time-limited circuit, and the synchronous circuit Q1
1 generates a signal for a predetermined period T12, and is composed of a monostable multivibrator or the like. In the device configured as described above, first, the synchronous circuit et+ performs a synchronization as shown in (b) at the phase θ0 where the input DC voltage of the inverter (A) shown in Fig. 1 (b) is the lowest. Generate a signal. When this synchronization signal is input, the delay circuit @ generates an output signal for a predetermined period after being delayed by a delay time td.

This situation is shown in 1k (c). The time limit circuit (c) receives a synchronizing signal as an input and generates an output signal for a predetermined period T12, as shown in (a). Therefore, at the time of starting, the transistor αG of the control device (Bl) has two phases: 01 to θ (period T1) and θg to θ2 (period T, 2), as shown in FIG.
) is conductive for a period of T1, so the inverter (
A) also generates an output during this period. It is possible to set the periods T11 and T12 as appropriate between the busy period T1, but as shown in FIG.
There are the following advantages when it is set longer than .

When dimming the discharge lamp of this type of device, an AC power source (1
) and the full-wave rectifier (3), a dimming device including a phase control element such as 8CR may be interposed, and the output voltage of this dimming device may be phase-controlled to dim the discharge lamp. In such a case9 For example, even if the output voltage of the dimmer is reduced by phase control, the preheating of the electrodes of the discharge lamp during startup is longer than the period T11, which is Tt2, so it will not decrease much. You don't have to do it.

Furthermore, if TOY is made longer than T11, there are the following advantages.

In other words, at the time of startup, there is a period T1 in which the inverter (A) is generating output and a period T2 in which it is stopped.
A current suddenly begins to flow into the inverter at phase θ in FIG. 1H), which may generate kf. However, T11
If T12 is set longer, the starting phase of T11 θ
1, the power generated by the inverter is 0 in the latter half of T12.
Since it is smaller than 2, the noise is reduced.

As explained above, not only when the DC voltage supplied to the inverter (A) is full-wave rectification of pulsating current, but also when the AC voltage is supplied with 9-phase control using a dimmer, etc. It is clear that the device of the present invention can be applied if the voltage full-wave rectified by the full-wave rectifier (3) is made to correspond to K (7) in FIG.

Furthermore, if the DC voltage supplied to the inverter (A) is smoothed by connecting a capacitor to the output terminal of the full-wave rectifier (3) in Figure 6, for example, the DC voltage as shown in Figure 1 (
), with an appropriate period T.

A similar effect was obtained by setting the output generation period T1 of the inverter (A). It is preferable that T corresponds to each half cycle of the AC power supply (1).

In this case, an oscillation circuit for generating an appropriate period T and a monostable multivibrator for setting an appropriate period T1'4 may be used in the control device (B).

In addition, as mentioned above, when smoothed DC voltage is supplied to the inverter (Al), the voltage applied to both ends of the discharge lamp (6) is changed to start discharging when the electrodes are preheated. If the temperature is set near the limit value, the discharge lamp will start lighting as soon as the electrodes are preheated by continuing the operation as shown in Figure 1 at startup. The control device (Bl) may be one that detects the current of the discharge lamp (6) and performs the same operation instead of the timer device (01).

Furthermore, in the embodiment of the present invention, the electrode (6a) of the discharge lamp
, (6b) as a device for preheating (inverter section)
The filament winding (5F) installed in the output transformer (5)
) from the output.

However, not only the inverter (mu) but also the control device (fB)
It is a matter of course that the structure is not limited to that shown in the example, and may have other configurations.The preheating of the 9% L pole is It is also possible to insert an impedance into the lamp, and the method can be applied not only to one discharge lamp but also to two or more lamps.

In addition, in the explanation of the above operation, the period T2 during which the output is stopped is
We have explained the case where the inverter does not generate any output during this period, but in a device in which a means is added to limit the output voltage to such that the discharge lamp does not cold start even during the period T2, Output may also be generated within the period T2, and the device of the present invention can be similarly applied in this case as well.

As described above, according to the device of the present invention, it is possible to avoid a cold start when starting a discharge lamp and to set appropriate conditions for preheating the electrodes.

This has the advantage that damage to the electrodes of the discharge lamp during startup can be reduced.

[Brief explanation of drawings]

1 through 5 and FIG. 1 are diagrams for explaining the operation of an embodiment of the present invention, and FIGS. 6 and 8 are circuit diagrams each showing an embodiment of the apparatus according to the present invention. be. In the figure, (old AC power supply, (2) is a switch, (3) is a full-wave rectifier, (6) is a discharge lamp s (6a) * (6'b
) is the electrode, (A) is the inverter, (B) is the control device, (
C) is a timer device. Note that the same reference numerals in the figures indicate the same or corresponding parts. Agent Makoto Kuzuno - Figure 1 IJt flθ2 θtθpθ2 (?, θ, θ
2 Fig. 2 1 Pre-feeding voltage Vpo VF Lead 1 to period ratio Kime 160χ

Claims (1)

[Scope of Claims] (1) A device for lighting a discharge lamp with an inverter that exchanges a full-wave rectified DC voltage of an AC power supply into a high-frequency AC voltage, and preheating the electrodes of the discharge lamp from the output of the inverter. At the time of starting the discharge lamp, a period of stopping the application of the output of the inverter to the discharge lamp is provided for each half cycle of the AC power supply, and thereafter, the period of stopping is reduced to start the discharge lamp. The voltage applied to the discharge lamp at the time of starting the discharge lamp is configured to be turned on, and the voltage Q applied to the discharge lamp when the discharge lamp is turned on is Q.
, 2 Y (W Discharge lamp lighting device according to claim 11. (31) The period during which the application of the output is stopped is set to include a period in which the voltage value of the DC voltage is Q8 or more with respect to its peak value. The discharge lamp lighting device according to claim (1) or (2), characterized in that: (4) At the time of starting, the period during which output is generated is set such that the instantaneous value of the DC voltage is the minimum. The discharge lamp lighting device according to any one of claims 1 to 131, characterized in that the discharge lamp lighting device is provided continuously before and after the phase. The period T11 before the phase θG with the minimum value is set to be longer than the period T1
The discharge lamp lighting device according to any one of items 1) to (4). (6) The stopping period is set so that the period Tt2 before the phase θ0 where the instantaneous value of the DC voltage is the minimum is longer than the previous period T11.
The discharge lamp lighting device according to any one of Items 11 to (4).