JPS61203597A - Discharge lamp high frequency lighting apparatus - 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 a device for lighting a discharge lamp at high frequency.

[Prior art and its problems]

In today's world where people are clamoring for energy conservation, the wave of energy conservation is also hitting the lighting field, and efforts are being made to reduce power consumption.

Techniques for reducing power consumption in lighting include (1) improving the luminous efficiency of light sources, reducing power loss in lighting devices, and systematically managing operations using software such as appliance efficiency meters and lighting control;
3) Three methods have been considered for increasing so-called visual efficiency, such as improving the sense of brightness. Among these, improving device efficiency is the basis of power saving and is one of the most important factors.

Fluorescent lamps, which are originally high-efficiency light sources, can be said to be a light source suited to the energy-saving era, but power-saving lamps have been developed and put into practical use with the aim of further improving their luminous efficiency. On the other hand, there are ways to reduce the power loss of the ballast as a way to save power in lighting devices, such as changing the material of the conventional ballast made of iron and copper to save energy and stabilize the lamp current at commercial frequencies. There are no-brid electronic ballasts that replace some of the impedance-based starting/maintaining circuits with semiconductor devices, but there is a limit to how much power loss can be reduced.

Against this background, the high frequency lighting of fluorescent lamps is based on the above 2.
In recent years, the Lra' Nissen Tsuri τ1 HaA- has been found to have a 44-power effect, and the luminous efficiency of the lamp is about 10 to 20 degrees higher than when lit at commercial frequency. Although it has been known for a long time that the lamp temperature increases, it has been limited to some special applications due to technical problems and cost performance of lighting devices. However, with recent advances in semiconductor technology, power transistors with high breakdown voltage and high reliability have been developed, and high-frequency 8-core materials have been improved, and the possibility of realization is increasing.

As a conventional example that focuses on this point, a constant current type pushcable transistor inverter as shown in Fig.
High frequency lighting devices are known.

To explain this with reference to the same figure, l is an AC power supply, 2 is a noise filter, 3 is a starting circuit, 4 is an abnormality stop circuit,
5 is a discharge lamp. First, the commercial AC output from the AC power source 1 is rectified by the iode bridge 6. Normally, a smoothing electrolytic capacitor is connected after this, but a high power factor of 90 inches or more is achieved by operating with pulsating current except for this.

This pulsating voltage is generated by constant current inductor 7 and transistor 8.
, 9 to the primary winding 11 of the inverter transformer lO. A capacitor 12 is connected to both ends of the primary winding 11, forming a parallel resonant circuit. The pace of the transistor is the feedback winding 13 of the inverter transformer.
The base current is supplied by the bias resistors 14, 15, 16, and 17 while performing the excavation operation by the feedback action. 18 is a pace drive winding, and a diode 19. Together with the capacitor 20, it forms a low voltage supply circuit for the whole pace drive, which makes the base tl'iff appropriate and reduces the loss caused by the base drive resistance. Due to the feedback action of the winding 13, the transistors 8.9 are alternately turned on and off, and a sinusoidal AC voltage is generated in the winding 11.

On the other hand, the collector voltage of the transistor has a trapezoidal waveform due to the effect of the constant current inductor 7, and the loss due to VCB (5at) is reduced due to the small peak current. Further, due to the parallel resonance, the collector voltage becomes sinusoidal, and switching occurs when the collector voltage is zero, so the switching loss is very small.

However, on the other hand, the above device includes commercial ripples in the output, which not only does not improve the luminous efficiency of the fluorescent lamp but also causes flickering. Furthermore, since an isolation transformer is used, primary-secondary coupling becomes a problem, and depending on the structure, there is a risk of considerable loss. Furthermore, since a part of the secondary winding is always connected to the fluorescent lamp filament, a filament current flows even when the lamp is lit, causing heat loss and reducing efficiency.

[Purpose of the invention]

An object of the present invention is to eliminate the above-mentioned drawbacks and provide a high-frequency discharge lamp lighting device with higher efficiency.

[Key points of the invention]

According to the present invention, in the device for converting the output of an AC power supply into DC by a DC conversion circuit and further converting it into high frequency by a frequency converter to energize a discharge lamp, the DC conversion circuit is a rectifier circuit from the input side.

Therefore, in the discharge lamp high frequency lighting device according to the present invention, it is composed of a chopper circuit and a smoothing circuit.
By chopping the DC voltage that has been full-wave rectified by the rectifier circuit and then smoothing it by the smoothing circuit, the commercial impedance seen from the power supply side increases and the power factor improves.

Since the ripple is extremely low, flickering of the discharge lamp connected to the subsequent stage is eliminated. Also, because the frequency is high, the capacitance of the smoothing circuit capacitor becomes smaller.

The smoothing circuit is smaller and cheaper. Furthermore, by varying the conduction period of the transistor in the chopper circuit, the magnitude of the DC voltage can be freely changed.

It becomes possible to steplessly change the dimming of discharge lamps, and also allows high-capacity fluorescent lamps to be lit.

[Embodiments of the invention]

Hereinafter, the configuration of the present invention will be explained with reference to the embodiment circuit shown in FIG.

First, 21 AC power sources are input to the DC conversion circuit 23 via the noise filter 22. The DC conversion circuit 23 includes, from the input side, a rectifier circuit consisting of a diode bridge 24, a reactor 25, a transistor 26, and a transistor 2.
6, a diode 28, and a capacitor 2.
The smoothing circuit 50 consists of 9 smoothing circuits.

For example, a transistor 30 is provided at the next stage of the DC conversion circuit 23.
．． A frequency converter 32 consisting of an inverter circuit with 31 as a switching means is connected, and a series resonant circuit consisting of a capacitor 33 and a reactor 34 is configured on its output side.

That is, a saturation transformer 35 is inserted in series with this series resonant circuit to generate a secondary voltage according to the resonant current, and the transistors 30 and 31 are turned on and off alternately.

This causes series resonance to continue.

A discharge lamp 36 is energized across the capacitor 33 constituting the series resonant circuit, and is turned on with this shared voltage. Furthermore, diodes F39 and F40 are connected to both ends of the pair of filaments 37 and 38, that is, the capacitor 33, with their polarities facing each other, so that filament currents flow alternately. Capacitors 41 and 42 connected in parallel with the diodes 39 and 40 act as circuit protection means in the event of filament breakage or abnormal voltage. Furthermore, diodes 43 and 44 are connected for freewheeling, and a capacitor 45 with a relatively large capacity is connected for pumping.

Next, the operation of the apparatus configured as described above will be explained using the operation waveforms shown in FIG.

In Figure 2, a is the waveform after full-wave rectification, b is the 1,000-jots waveform, C is an enlarged view of the waveform, d is the smoothed DC voltage waveform, and e is the output waveform of the series resonant inverter.
The waveforms at both ends are shown.

The output of the AC Me power supply 21 is passed through a noise filter 22 and subjected to full-wave rectification by a diode bridge 24 as shown in FIG. 2a. The full-wave rectified DC voltage is chopped by a chopper circuit 49 that stores energy in the reactor 25 when the transistor 26 is turned on and discharges it when the transistor 26 is turned on, as shown in FIGS. Furthermore, this is diode 28
．． The voltage is smoothed by a smoothing circuit 50 consisting of a capacitor 29 to obtain a DC voltage as shown in d of the figure. According to the DC conversion circuit described above, since the input full-wave rectified voltage is directly chopped and smoothed, the commercial impedance seen from the power supply side increases and the power factor improves; , the flickering of the discharge lamp connected to the subsequent stage is eliminated. Furthermore, since the frequency is high, the capacitance of the capacitor 29 is small, making the smoothing circuit small and inexpensive. Furthermore, by varying the conduction period TI of the transistor 26,
The magnitude of the direct current voltage (DC) can be freely changed, making it possible to steplessly change the dimming of the discharge lamp, and also allowing the lighting of high-capacity fluorescent lamps.

Next, a frequency converter that is supplied with the output of the conversion circuit and converts it into a high frequency will be explained together with a series resonant circuit.

In the above circuit, the two transistors 30 and 31 as switching means are not completely balanced, so the starting circuit 4
When a signal is output from 6 to the base of transistor 31, transistor 31 becomes conductive, and current flows through capacitor 45 - diode 39 - capacitor 33 - filament 38 - reactor 34 - saturation transformer 35 - collector emitter of transistor 31. flows. Since the base of the transistor 31 is connected to the secondary winding 47 of the saturation transformer 35, automatic operation is performed.

On the other hand, the voltage induced in the secondary winding 48 by the saturation transformer 35 is kept off because it is in the direction of disconnecting the transistor 30. Thereafter, as the collector current of the transistor 31 increases rapidly, the magnetic flux generated in the saturation transformer 35 also increases over time. However, the magnitude of the magnetic flux generated in the transformer 35 reaches a ceiling at saturation flux and does not increase any further.

Therefore, the secondary voltage of the saturation transformer 35 is no longer induced, and the transistor 31 is turned off. Thereafter, the current decreases through the F+1-wheel diode 43 following the decreasing waveform of the series resonant circuit.

Next, when this current changes in the opposite direction due to the action of the series resonant circuit, the transistor 30 turns on in the same way, and the transistor 30, which is composed of a saturation transformer 35, a reactor 34, a diode 40, a capacitor 33, a filament 37, a capacitor 45, and a transistor 30, turns on. A current is passed through the closed circuit.

In this way, the transistors serving as switching means are alternately turned on and off, resulting in a series resonant inverter operation and generating a high-frequency alternating current voltage.

Since a discharge lamp 36 serving as a load is connected to both ends of this series resonant capacitor 33, an alternating current voltage almost like a sine wave is applied, thereby improving luminous efficiency. In addition, when starting a discharge lamp, a preheating current for the filament and a high discharge voltage are required, but since the discharge lamp has a high impedance at the time of starting, the weight flowing through the discharge lamp is extremely small, and the capacitor 3
3 and reactor 34, resulting in a high current,
High pressure is generated and the discharge lamp can be started easily. Therefore, instantaneous lighting is possible.

Diode 39 on both ends of filament 37.38
．． Connect 40 and alternately connect 11 to the filament! Since the loss is halved by increasing the current flow, it has the effect of reducing filament heat loss, especially when the lighting is stable.

Furthermore, since the load of the transistors 30 and 31 is a resonant current, no current flows when the transistors are turned on, and the loss is extremely small.

In the example circuit shown in FIG. 1, it is also possible to simultaneously light discharge lamps with different ratings by connecting a plurality of frequency converters from the current conversion circuit in parallel, and it is possible to simultaneously light discharge lamps having different ratings. Coupled with the variable conduction period and the stepless dimming effect of the discharge lamp, it is expected to have a significant effect in home indoor lighting (for example, jump rear lights, etc.) that requires a wide variety of versatility.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, a DC voltage that has been full-wave rectified by a rectifier circuit is chopped by a chopper circuit, and further smoothed by a smoothing circuit l, thereby maintaining an extremely stable discharge. The present invention has a great industrial effect in that an efficient discharge lamp lighting device can be constructed relatively easily.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram for explaining an embodiment of the present invention, and FIG. 2 is a waveform diagram of various parts for explaining the present invention. FIG. 1wc3 is a circuit diagram of a conventional discharge lamp high frequency lighting device. 21; AC power supply, 23; DC conversion circuit, 30° 31; Transistor, 32; Frequency converter, 33; Capacitor,
34; reactor, 35; saturation transformer, 36; discharge lamp, 49; chopper circuit, 50; smoothing circuit. Figure '1'2

Claims (1)

[Claims] 1) In a device that converts the output of an AC power supply into DC using a DC conversion circuit, and further converts it into high frequency using a frequency converter to energize a discharge lamp, the DC conversion circuit is connected from the input side to a rectifier circuit, a chopper circuit, and a smoothing circuit. A high-frequency lighting device for a discharge lamp characterized by comprising a circuit.