JPH0351276B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention provides a high-frequency lighting device for lighting a low-pressure discharge lamp (hereinafter referred to as a lamp) such as a fluorescent lamp or a rare gas discharge lamp at a high frequency and with a pause period in each half cycle. It is related to.

[Prior art]

Conventionally, Japanese Utility Model Publication No. 56-8160 discloses that lamp efficiency is improved when a rectangular waveform alternating current with a rest period is passed through a fluorescent lamp. This is said to be because the electrons in the lamp, which have cooled during the rest period, are rapidly accelerated during the application period, and the density of high-temperature electrons becomes higher than when the lamp is lit with direct current or commercial frequency. In addition, as a result of various studies conducted by the present inventors on low-pressure mercury vapor discharge lamps such as fluorescent lamps using high-frequency AC voltage with a rest period, the lamp efficiency was further improved than the value shown in Publication of Utility Model Publication No. 51-8160. It became clear that it was possible.

However, it was limited to Utility Model Publication No. 51-8160, 4
A device using an inverter that generates a rectangular wave output voltage, such as a device in which a lamp is connected to the diagonal of a bridge circuit with transistors arranged on the sides, and a rest period is formed by another transistor provided at the input end of the bridge circuit. In this case, even if the lamp efficiency was improved, the overall efficiency of the entire device was insufficient, the capacity of the device tended to increase, or the radio noise was large.

The present inventors previously proposed an apparatus shown in FIG. 1 to improve these points. Next, this device will be briefly explained.

In the figure, 11 is a smoothed DC power supply, 15 is a well-known self-excited push-pull transistor inverter, and a substantially sinusoidal high-frequency output voltage is generated on the secondary side of a transformer 18. 16 is inverter 1
A fluorescent lamp, which is a low-pressure discharge lamp, is connected between the output terminals of the lamp 16.
23 is a current-limiting impedance for maintaining the current of the lamp 16 at a predetermined value, and A is a preheating winding that preheats the lamps 16 and 16.
6, a full-wave rectifier circuit 24 whose AC end is connected in parallel with the lamp 16;
A transistor 25 is arranged at the DC end of this rectifier circuit 24. A control device 19 controls the operation of the transistor 25.

Next, the configuration of this control device 19 is shown in FIG.
33 is a current transformer that detects the output current of the inverter 15 and inputs it to the control device 19. Further, 34 is an output resistance of the current transformer 33, 35 is a full-wave rectifier that rectifies the output of the current transformer 33, 31 is a constant voltage diode connected from the full-wave rectifier 35 through a resistor 32, and 36 is for driving. It is a DC power source, and can be configured by rectifying and smoothing the output of an auxiliary winding provided in the transformer 18 of the inverter 15, for example.
3B shows the output voltage of the current transformer 33, and FIG. 3A shows the output of the full-wave rectifier 35.
Naturally, it has approximately the same phase and similar waveform to the output current of the inverter 15.

In such a configuration, when the power supply 11 is turned on, the transistors 21a and 21b of the inverter 15 are alternately opened and closed as is well known, and the inverter 15 starts self-oscillation and generates a high frequency voltage.

When lamp 16 begins discharging, current transformer 33 generates an output voltage. At this time, constant voltage diode 3
1, as shown in FIG. 3B, the transistor 29 becomes conductive during the period _T1a including the maximum instantaneous value of the output current of the inverter 15, and the transistor 25 is cut off. Therefore, during this period T _1a , the discharge current of the lamp 16 flows as shown in the hatched area in FIG.

When a current near the maximum instantaneous value of the output current of the inverter 15 flows through the lamp 16 in this way, the capacity of the device can be reduced and the efficiency of the device can be improved compared to the case where this is not the case.

However, although this conventional device has the advantage that the instantaneous value _A1 of the lamp current when current begins to flow through the lamp 16 is a constant value regardless of fluctuations in the power supply voltage, etc., it has the following disadvantages.

That is, when the input DC voltage of the inverter 15 has many ripples, for example, when voltages such as those shown in FIG. Also, the period T _1a (see FIG. 3) during which current flows through the lamp 16 becomes longer. For this reason, when the AC power supply 12 increases, the power consumption of the lamp 16 increases even more, and the so-called power supply voltage fluctuation characteristics worsen, and even if the AC power supply does not fluctuate, the input DC voltage of the inverter 15 increases. When there are many ripples, there is a problem that the lamp power consumption for each half cycle of the high frequency changes greatly.

[Summary of the invention]

This invention was made in view of the above problems.
By configuring the period for supplying current to the lamp in response to the magnitude of the output current of the inverter or the instantaneous change in the input DC voltage of the inverter, and minimizing the change in lamp power consumption during each half cycle, the current to the lamp can be adjusted. An object of the present invention is to provide a discharge lamp lighting device that can reduce changes in lamp power during each half cycle by appropriately setting a period for flowing the lamp.

[Embodiments of the invention]

Embodiments of the present invention will be described below based on the drawings. FIG. 5 shows an example of a control device 19 for a discharge lamp lighting device according to the present invention, which is applied to, for example, the device shown in FIG. In FIG. 5, 33 is a current transformer, 34 is a resistor, 35 is a full-wave rectifier, 44 and 45 are resistors that detect and divide the inverter output current in each half cycle, 39 is a diode, 40 is a capacitor, and 41 is a The terminal voltage of the capacitor 40 is the envelope of the output current peak value of the inverter 15 or the terminal voltage of the inverter 15.
The voltage is similar to the input DC voltage. 42 is a constant voltage diode, 43 is a resistor, 46 is a voltage comparator,
47 is a resistor, 36 is an auxiliary DC power source for driving, and 25 is a transistor of switch device A.

Next, the operation when the control device 19 configured as described above is used in the discharge lamp lighting circuit shown in FIG. 1 will be described. Assume that the inverter 15 is now operating and the lamp 16 is lit. Then,
The signal obtained by the current transformer 33 causes the voltage comparator 4 to
A fluctuating voltage of the inverter output current peak value envelope is applied to the input terminal B of No. 6 as shown in FIG. 6A.
Further, a voltage similar to the high-frequency output current is applied to the input terminal A, as shown by the broken line in FIG. 6A.
In this way, the voltage comparator 46 operates during a period in which the voltage at terminal A is higher than that at terminal B, that is, D ₁ in FIG. 6A.
During the period _D2 , the output transistor is conductive, and the output terminal C is at L level (as shown in Figure 6C).
becomes. Therefore, during these periods D ₁ and D ₂ , the transistor 25 is non-conductive and current flows to the lamp 16 side. As is clear from the voltage at terminal B, even when the peak value of the inverter output current is large, the period during which current flows through the lamp 16 increases compared to when the peak value is small.
In other words, it is possible to prevent D ₁ <<D ₂ from occurring. Also, the setting of the period D ₁ when the peak value is small and the peak value D ₂ when the peak value is large is set by the resistor 44,
45 voltage division ratio and constant voltage diode 42 Zener
It can be set appropriately by selecting the voltage.

In the above embodiment, control was performed in accordance with the peak value of the inverter output current, but the high frequency component is removed from the output voltage of the winding provided in the transformer 18 of the inverter 15, rectified, and the voltage comparator 46 outputs the current. The voltage may be controlled according to the input voltage of the inverter 15 by means such as applying the voltage to the terminal B of the inverter 15. In addition, when the inverter output current peak value is lower than a predetermined value, for example, the currents shown in Figure 4 B and D
It may be set so that the lamp current does not have a rest period during a period lower than A _L.

In the above description, the control device 19 uses the current transformer 33, but other methods such as detecting the current using a resistor or the like may be used.
Also, the period during which current is supplied to the lamp is determined by the voltage comparator 4.
6, but other means may be used. Further, in the embodiment, the switch device A is a combination of the rectifier circuit 24 and the transistor 25, but the same effect can be obtained by using another switching element such as a field effect transistor.

The inverter 15 may be a series inverter or a bridge inverter equipped with an output transformer, for example, as long as a substantially sinusoidal output voltage can be obtained at the output terminal, and the inverter 15 may have a current-limiting impedance that sets the lamp current to a predetermined value. 23 may be a capacitor of capacitive reactance instead of an inductance of inductive reactance.

In the above description, a case has been described in which the chiyoke coil 23 is used at the output end of the inverter 15, but the transformer 18 of the inverter 15 may be configured as a leakage transformer.

It is possible to arrange the switch device A in ways other than those in the embodiments, such as providing an additional winding with a polarity opposite to the secondary winding 18S of the transformer and connecting the switch device A via this, or connecting the transformer 18 to a leakage transformer. In this case, the secondary winding may be provided with an intermediate tap and connected to the low-voltage electric path formed by this intermediate tap. Alternatively, a mempedance may be connected in series with this switch device A to reduce the current flowing through the switch device. Alternatively, a switch device A may be connected in parallel with the lamp 16 via its electrodes 16f, 16f, and a preheating current may be caused to flow when the switch device A is turned on. Further, when starting the lamp 16, a means may be added to keep the switch device A inoperative for a certain period of time in order to stabilize the discharge even after the start of discharge. This can be done, for example, by providing a timer circuit that maintains the output of the output terminal C of the voltage comparator 46 in the embodiment shown in FIG. This can be realized by providing the output terminal and controlling the output of the output terminal.

Further, the input DC voltage of the inverter 15 is the first
In addition to using a rectified and smoothed current as shown in the device shown in the figure, it is also possible to use a pulsating DC voltage as shown in Figure 4 (A), or a DC voltage that is not completely smoothed as shown in Figure 4 (C) and combined with an appropriate auxiliary DC power supply. It may also be possible to use a DC voltage such as a DC voltage configured using a DC voltage.

Although the frequency of the inverter 15 was not particularly mentioned in the above description, as disclosed in detail in Japanese Patent Application No. 110369/1980, the improvement in lamp efficiency obtained by providing the rest period T ₀ is approximately 1 KHz per kilohertz. It was observed that even at 80KHz, a considerable efficiency improvement was obtained. However, from the viewpoint of preventing unpleasant audible noise, the frequency is preferably about 17 KHz or higher, and when a bipolar transistor is used as the transistor 25, the frequency is preferably 100 KHz or lower in order to reduce switching loss.

In the above embodiment, there was only one lamp 16, but
For example, a similar effect can be obtained with two or more lamps 16 connected in series.

Furthermore, in the above embodiment, the low-pressure discharge lamp was a fluorescent lamp 16, but the improvement in lamp efficiency by providing a rest period T ₀ is also recognized in rare gas discharge lamps such as neon lamps and krypton lamps.
This invention can also be applied to those low pressure discharge lamps.

〔Effect of the invention〕

As described above, according to the present invention, the discharge lamp lighting device is configured by changing the lamp power supply period of each half cycle so as to suppress changes in lamp current. Even when the ripple of the input DC voltage is large, the period during which current is passed through the lamp can be appropriately set, and there are effects such as being able to reduce changes in lamp power during each half cycle.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a general discharge lamp lighting device, FIG. 2 is a circuit diagram of a control device of the same discharge lamp lighting device, and FIGS. 3 and 4 are operation explanatory diagrams of the same discharge lamp lighting device, respectively. FIG. 5 is a circuit diagram showing a control device for a discharge lamp lighting device according to an embodiment of the present invention, and FIG. 6 is an explanatory diagram of the operation of the same discharge lamp lighting device. 15...Inverter, 16...Lamp, 19...
...control device, A...switch device. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A smoothed DC power source obtained by rectifying and smoothing an AC power source,
An inverter that converts the DC voltage of this DC power supply into a nearly sinusoidal high-frequency voltage, a low-pressure discharge lamp to which the output of this inverter is input via a reactive current-limiting impedance, and a low-pressure discharge lamp that converts the output of the inverter into A switch device connected in parallel with the inverter output current is applied to obtain a voltage corresponding to the inverter's output current peak value envelope line voltage or the inverter's input voltage and the inverter's high-frequency output current. A discharge lamp lighting device comprising a control device that shuts off a switch device when the voltage applied is higher than the envelope voltage or the input voltage of the inverter.