JPS62226598A - Discharge lamp burner - 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 [Field of Industrial Application] The present invention relates to a discharge lamp lighting device for lighting a discharge lamp such as a high-pressure discharge lamp at high frequency.

[Conventional technology]

Attempts have been made for some time to light discharge lamps, generally referred to as high-pressure discharge lamps, such as high-pressure mercury lungs and metal halide lungs, at high frequencies of several kilohertz or more. However, when lighting with a high frequency of a sine wave,
As disclosed in the publication, there was a risk that instability such as arc fluctuation would occur due to the occurrence of acoustic resonance phenomena.

To prevent this, it has been proposed to use square wave alternating current to turn on the lights. JP-A-57-61294 and JP-A-58-53195 show this type of conventional device,
FIG. 10 shows the device shown in Japanese Patent Application Laid-Open No. 58-53195.

In FIG. 10, 1 is a DC power source, which can be obtained by rectifying and smoothing a commercial power source.

2 is an inverter that generates high frequency voltage, and transformer 2
0, and a pair of switching transistors 22.0 for alternately and periodically supplying currents in opposite directions from the DC power supply 1 to the primary side of the transformer 20(7) via the reactor 21.
23, it self-oscillates with the help of the tertiary winding of the transformer 20, a capacitor 24, and a resistor 25.

The high-frequency AC output of the inverter 2 is passed through a DC limiting element 3 and subjected to full-wave rectification in a rectifier circuit 4. This full-wave rectified DC voltage is smoothed by a capacitor 5 and applied to a rectangular wave generation circuit 6 composed of a Pritzno-type input circuit.

The rectangular wave generating circuit 6 includes four switching transistors 61 to 64 connected in a single-phase grid connection, and diodes 65 to 68 connected in antiparallel to each of the switching transistors 61 to 64. The output of this rectangular wave generating circuit 6 is supplied to a discharge lamp 7 as a load via an actuator.

In FIG. 10, the terminal voltage of the capacitor 5 obtained by rectifying and smoothing the output voltage of the inverter 2 is converted into a rectangular wave generating circuit 6.
Depending on the opening and closing of the switching transistors 61 to 64,
It is converted into a rectangular wave alternating current and supplies power to the discharge lamp 8.

In this way, the discharge lamp is lit with rectangular wave power rather than sine wave power, so even if the discharge lamp is lit with high frequency, the acoustic I/O remains constant.
It is possible to prevent the +@ phenomenon from occurring.

[Problem that the invention seeks to solve]

In conventional discharge lamp lighting devices, a bridge-type transistor inverter is used as a high-frequency rectangular wave generating circuit, and the rectangular wave generating circuit 6 and a driving circuit (not shown) for these switching transistors tend to be expensive. There was a problem.

The present invention was made to solve these problems, and enables the use of a relatively simple square wave generation circuit.
Another object of the present invention is to provide a discharge lamp lighting device that can simplify the drive circuit.

[Means for solving problems]

A discharge lamp lighting device according to the present invention is provided with a rectangular wave generation circuit driven by an output signal of an inverter.

[Effect]

In this invention, the output current of the inverter is limited by the current-limiting impedance, and is converted into a high-frequency rectangular waveform output by a rectangular wave generation circuit that operates at the output frequency of the inverter, and this output is used to drive a high-pressure discharge lamp. Light.

〔Example〕

Embodiments of the discharge lamp lighting device of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram showing one embodiment thereof. In FIG. 1, 1 is a DC power supply, and 2 is an input/9-input circuit that generates a high frequency voltage. This inverter 2 mainly includes an output transformer 20 and a pair of switching transistors 22 and 23.

Primary winding #i of output transformer 20! The positive electrode of the DC power source 1 is connected to the midpoint of 20P via the reactor 21t. Both ends of the primary winding 20P are connected to the collectors of switching transistors 22 and 23. The emitters of the switching transistors 22 and 23 are commonly connected to the negative electrode of the DC power supply 1.

A series circuit of a resistor 27 and a thyristor 33 is connected between the positive and negative poles of the DC power supply 1.

From the connection point between this resistor 27 and the thyristor 33, a resistor 25
．． 26'e respectively through the switching transistor 2
Connected to a pace of 2.23.

The switching transistors 22 and 23 are connected across the feedback winding d20B of the output transformer 20, and the capacitor 24 is connected across the primary winding 20P.
is connected. These capacitors 24 and resistors 25
．． 26 and the feedback winding 20B, the switching transistors 22 and 23 are configured to self-oscillate.

Furthermore, a winding X is provided on the secondary side of the output transformer 20. This winding X is made of metal and is used to detect an abnormal state of the high pressure discharge lamp 8 such as a ride lamp. If this high pressure discharge lamp 8 does not light up normally, the voltage at both ends of the winding X increases. be.

Both ends of this winding X are connected to the input end of the rectifier circuit 28. A resistor 29 and a resistor 3 are connected between the output terminals of the rectifier circuit 28.
0, a capacitor 31 is connected in a "π" type, and the output voltage of the rectifier circuit 28 is smoothed by these. A connection point between the resistor 30 and the capacitor 31 is connected to the dart of the thyristor 33 via a constant voltage diode 32. When the voltage of the capacitor 31 exceeds a predetermined value, the voltage regulator diode 32 turns on and the thyristor 3
3 is turned on, and the switching operation of the switching transistors 23 and 24 is stopped.

The output transformer 20 further includes a winding Y on the primary side. In this way, the inverter 2 is configured.

A series circuit of a diode 12 and a capacitor 13 is connected between both ends of this winding M;jY. Also, winding Y
One end of the transistor 14 is connected to the base of the transistor 14 via a diode 11 and a resistor 16.

A resistor 17 and a transistor 14 are connected in parallel to the capacitor 13.
series circuit is connected. The collector of this transistor 14 is connected to the pace of the transistor N meta 15 via a resistor R+k. A series circuit of transistor 15 and resistor 18 is connected to capacitor 13 in parallel.

The collector of transistor 15 is connected to resistor 19 and capacitor C.
It is connected to the pace of transistor 93 in rectangular wave generating circuit 9 through a parallel circuit with I.

In this way, the drive circuit 10 is configured. Drive circuit 1
0 opens and closes this transistor 93 at high frequency.

Both ends of the secondary winding 20S of the output transformer 20 are connected to the input end of the rectifier circuit 4. A smoothing capacitor 5 is connected between the output terminals of the rectifier circuit 4. The DC voltage across the capacitor 50 is applied to the rectangular wave generating circuit 9.

That is, a series circuit of a coil 91, a capacitor 92, and a high-pressure discharge lamp 8 is connected between both ends of the capacitor 5, and a connection point between the coil 91 and the capacitor 92 and the negative voltage side of the capacitor 5 are connected to each other. Collector of transistor 93
Emitter is connected. A diode 94 and a capacitor 95 are connected in parallel to this transistor 93.

Next, the operation of this invention will be explained.

As is well known, the inverter 2 alternately opens and closes the switching transistors 22 and 23 by the action of the feedback winding 20B provided in the output transformer 20, etc., and generates a high frequency voltage of, for example, more than ten KHz.

Assume that the high-pressure discharge lamp 8 is not yet lit. At this time, almost no current flows through the secondary winding 20S of the inverter 2, so the resonant frequency of the resonant circuit determined by the inductance of the capacitor 24 and the output transformer 200 winding is a lower frequency than when the high-pressure discharge lamp is lit. becomes.

In theory, the inverter 2 operates at an output frequency f determined by the above-mentioned resonant circuit. Also, the output frequency of the in/output 2 when the high pressure discharge lamp 8 is lit is the output frequency of the output transformer 2.
A load current flows through the secondary winding 208 of 0, and the output frequency f,
This results in a higher frequency f2.

Since the output transformer 20 is configured as a leakage transformer and the current in the secondary winding 20S is limited by the leakage inductance, an excessive current will not flow even immediately after the high-pressure discharge lamp 8 starts discharging. do not have.

Next, the operation of the rectangular wave generation circuit 9 will be explained. The output voltage of the winding Y provided in the output transformer 20 of the inverter 2 makes the transistor 14 conductive every half cycle of each period, and as a result, the transistor 93 of the square wave generating circuit 9
open and close at the same cycle.

When the transistor 93 is off, a current of charge to the capacitor 92 flows to the high-pressure discharge lamp 8 through the coil 91, and when the transistor 93 is on, a current of discharge from the capacitor 92 flows to the high-pressure discharge lamp 8. In this way, a high-frequency alternating current having a substantially rectangular waveform is passed through the high-pressure discharge lamp 8, and the lamp is stably lit.

The capacitor 95 of the rectangular wave generating circuit 9 is a resonant capacitor provided to facilitate the start of discharge of the high-pressure discharge lamp 8.l) It generates a high voltage by the action with the coil 91, and applies it to the high-pressure discharge lamp 8. Therefore, be prepared as necessary. A diode 94 is also provided if necessary.

Furthermore, it is advantageous to set the output frequency of the inverter 2 so that fl<ft because the capacitance of the smoothing capacitor 5 can be reduced.

Conversely, if the output frequency of the inverter 2 is set such that fl>f, the capacitance of the resonance capacitor 95 can be small.

Although the output transformer 20 of the inverter 2 is a leakage transformer, if another choke coil is provided in series with the rectifier circuit 4, it does not necessarily have to be a leakage transformer, but this is somewhat inferior in terms of miniaturization of the device.

FIG. 2 is a circuit diagram showing only the different parts from FIG. 1 of another embodiment of the present invention. In the case of this FIG.
and switching transistor 22.2 of inverter 2
This also serves as a winding for DC voltage generation (based on diode 5o and capacitor C2) for supplying pace current to circuit 3, which simplifies the device.

The rectangular wave generating circuit 9 is different from the configuration of the embodiment shown in FIG.
In the case of the conventional discharge lamp lighting device shown in Fig. 10 or a half-grit square wave generation circuit in which two transistors are connected in series and two capacitors are connected in series, the drive circuit shown in Fig. 1 is used. In the same configuration as 10, in order to obtain the remaining half-cycle signals, another set of drive circuits may be further provided to open and close the plurality of transistors of the rectangular wave generating circuit in opposite phases to each other.

An example of such a rectangular wave generating circuit is shown in FIG. In this case as well, the diodes 94a and 94be may be connected in antiparallel to the transistors 93a and 93bK, or the resonance capacitor 95 or equivalent may be connected in parallel to the high pressure discharge lamp 8.

FIG. 4 shows a diagram for explaining the operation of the rectangular wave generating circuit of the embodiment shown in FIGS. 1 and 3.

Although FIG. 4 shows the voltage waveform of the high-pressure discharge lamp 8, the current waveform is also almost the same due to high frequency lighting.

In this FIG. 4, 1. Instantaneous value k a, ,
t.

Assuming that the instantaneous value at is a, the period from tl to t corresponds to the time when the transistor 93 of the rectangular wave generation circuit 9 is turned off. In the device of FIG. 3, transistors 93a, 9
3b is off.

Next, after the transistor 93 is turned on, the instantaneous value at the peak value b1 and t3 (in the diagram, the same time t2 is set for convenience of explanation) is set as t3, and the values A and B are determined as follows.

A=b2/b0. B=a1/bI This A represents the completeness of the square wave, and the closer it is to "1", the more
It becomes a square wave, and as it becomes smaller, it approaches a differential waveform.

Further, B represents the degree of symmetry of the current supplied to the discharge lamp on the positive and negative sides, and the closer it is to "1", the more symmetrical the waveform is.

Here, T indicates the period of the rectangular wave.

When the value of A becomes small, the discharge lamp shifts to an unstable lighting state of the arc due to the acoustic resonance phenomenon, but at 100W
The mercury rung and 100W metal halide rung have 0.
In the region of 4<A, noticeable flickering hardly occurs.

However, when the arc was observed in detail, it was found that the region of 0.55<A was a stable discharge in which the arc hardly moved.

The value of A and the capacitor 92 (92a in FIG. 3).

92b) is a characteristic diagram showing the relationship between capacitances, and A
This shows that in order to make the value 0.85 or more, the capacity increase is significant and uneconomical.

In this figure, a 100W mercury rung is lit at the rated current, and the constants of the coil 9 and capacitor 92 are set so that the value of B becomes 0.95 < B < 1.05. , the frequency of the square wave is 25 KHz. When the lighting frequency was changed from 25 KHz to 35 KHz, the same tendency as in FIG. 5 was observed. Note that the portion indicated by the arrow Y1 in FIG. 5 is a region where flickering due to instability of the arc is not noticeable.

FIG. 6 is a diagram showing the relationship between the inductance of the coil 9 and the value of B when the capacitance of the capacitor 92 is used as a parameter. In FIG. 6, the value of B had a wide range of effects, including the stability of the discharge, the wear of the electrodes of the high-pressure discharge lamp, and the temperature distribution of the arc tube.

The results of the continuous lighting test revealed that a range of about 0.8 < 8 < 1.2 is acceptable for practical use.

FIG. 7 shows an investigation of the influence of the inductance of the coil 91 on the current value of the high-pressure discharge lamp.
1 acts as a current source, so it only needs to have a sufficiently large inductance. This is a characteristic when using a full-scale silver lamp, but in the case of other discharge lamps, for example, 100 W.
Almost the same results were obtained with metal halide dragons.

FIG. 8 shows a third embodiment of the invention. This prevents an excessive peak current of the discharge lamp, especially when the rung is in a low impedance state immediately after the discharge of the lamp 8 starts.

This is due to the action of the second coil 98. Here, when the transistor 93 is off, the coil 9
Since the current flows to the high pressure discharge lamp 8 through the coil 1, the second coil 98 is not necessary, and the diode 97 is connected as shown in the figure.
The second coil 98 may be inserted while the transistor 93 is on.

The second capacitor 95 and diode 96 may be connected as necessary, as in the embodiment shown in FIG.

FIG. 9 shows the main part of the fourth embodiment of the present invention, and the second embodiment
When the resistor 99 is connected in series with the capacitor 95, excessive voltage is prevented from being applied to the transistor 93.

! In addition, for this purpose, it is also effective to connect a voltage suppressing element such as a varistor in parallel with the transistor 93. Although not mentioned in the explanation of each of the above embodiments, the DC power supply 1 rectifies the commercial AC power supply. You may use what you have obtained or obtained by other means.

Although the inverter 2 may have a configuration other than the Bushgur type tranometer imperter using a resonant circuit, it is more convenient to use one that performs self-excited oscillation operation or one that uses a leakage transformer as an output transformer. .

Furthermore, the rectifier circuit 4 may be a full-wave rectifier circuit other than a full-wave rectifier circuit using a diode glitch, or a center-tag full-wave rectifier circuit using two diodes isometrically by providing a center tag in the output winding of the output transformer 20. You can also use it as

The means for stopping the operation of the inverter 2 when the high-pressure discharge lamp does not light up for a long time is not limited to the one in the embodiment, but may be one that repeatedly operates and stops, or a means for stopping the operation of the high-pressure discharge lamp 8.
It is possible to use devices that detect abnormal discharge (asymmetric discharge) and devices that do not.

In either device, at least the loss of the transistor 93 of the rectangular wave generation circuit 9 can be reduced when the high-pressure discharge lamp 8 goes out of operation due to its lifespan or the like.

Further, as the switching element of this rectangular wave generating circuit 9, in addition to the normal transistor of the embodiment, using an MO8 field effect transistor (MOSFET) is effective in reducing switching loss.

〔Effect of the invention〕

As described above, the present invention uses the output signal of the inverter to drive the rectangular wave generation circuit, so the configuration of the device can be simplified, and furthermore, even if the wave is not a perfect rectangular wave, the discharge is stable or the arc is not fluctuated. The advantage is that high-frequency lighting can be performed without worrying about

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of an embodiment of the discharge lamp lighting device of the present invention, FIG. 2 is a circuit diagram of a portion different from FIG. 1 of the second embodiment of the discharge lamp lighting device of the present invention, and FIG. The figure is a circuit diagram of another embodiment of the rectangular wave generating circuit in the discharge lamp lighting device of the present invention, FIG. 4 is a diagram showing the voltage waveform of the high pressure discharge lamp in the discharge lamp lighting device of the present invention, and FIG. A diagram showing the relationship between the capacitance of the capacitor of the rectangular wave generating circuit and the completeness A of the rectangular wave in the discharge lamp lighting device 1 of the present invention, and FIG. Figure 7 is a diagram showing the influence of the inductance of the same fill on the current value of the high-pressure discharge lamp; Figures 8 and 9 are diagrams showing the relationship between the degree of symmetry B on the positive and negative sides of the current supplied to the lamp; The figures are circuit diagrams of further different embodiments of the rectangular wave generating circuit in the discharge lamp lighting device of the present invention, and FIG. 10 is a circuit diagram of a conventional discharge lamp lighting device. ■... DC power supply, 2... Inverter, 4... Rectifier circuit, 8... High pressure discharge lamp, 9... Rectangular wave generation circuit,
lO...drive circuit. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (12)

[Claims] (1) An inverter that generates a sinusoidal high-frequency voltage, a rectangular wave generating circuit that is driven by the output signal of this inverter and converts the DC output obtained by rectifying and smoothing the inverter output into a high-frequency rectangular wave voltage, and this rectangular wave generating circuit A discharge lamp lighting device comprising a high-pressure discharge lamp that is lit with an output of. (2) The inverter is composed of a transistor inverter that performs self-excited oscillation, and the output frequency of this inverter is configured to be lower before the high-pressure discharge lamp starts discharging than when it is lit. A discharge lamp lighting device according to claim 1. (3) The discharge lamp lighting device according to claims 1 and 2, wherein the output transformer of the inverter is constituted by a leakage transformer. (4) The inverter is configured to stop its operation when the high-pressure discharge lamp does not discharge for a predetermined period or continues asymmetrical discharge. The discharge lamp lighting device according to item 3. (5) The rectangular wave generation circuit calculates the ratio A=b_2/b_1 of the peak value b_1 near the rising edge and the peak value b_2 near the falling edge in a half cycle of the voltage of the high-pressure discharge lamp, and The ratio of the peak values a_1 and b_1 of each positive and negative half cycle B = a_1/b_1 is set to 0.
．． 4. The discharge lamp lighting device according to claim 1, wherein the discharge lamp lighting device generates an output such that 4<A and 0.8<B<1.2. (6) The rectangular wave generation circuit includes a resonant circuit that resonates or almost resonates with the output frequency component in a state before the start of discharge of the high-pressure discharge lamp, and applies the resonant voltage to the high-pressure discharge lamp. A discharge lamp lighting device according to any one of claims 1 to 4 or 5, characterized in that the discharge lamp lighting device is constructed as follows. (7) The rectangular wave generation circuit is characterized in that it includes a series circuit of a first coil and a transistor that is periodically opened and closed, and a series circuit of a first capacitor and a high-pressure discharge lamp as a load connected in parallel to this transistor. A discharge lamp lighting device according to claims 1 to 5 or 6. (8) The discharge lamp lighting device according to claim 7, wherein the transistor of the rectangular wave generating circuit is connected in parallel with at least one of a second capacitor and an anti-parallel diode. (9) A discharge lamp lighting device according to claim 7 or 8, characterized in that a second coil is connected in series to the series circuit of the high-pressure discharge lamp and the first capacitor. (10) A discharge lamp lighting device according to claim 9, characterized in that a diode is connected in parallel to the second coil to allow a current to flow through the charge of the first capacitor. (11) Claim 8, characterized in that the rectangular wave generating circuit has a varistor connected in parallel with the second capacitor, or a resistor connected in series, to limit the voltage between the terminals of this capacitor. and the discharge lamp lighting device according to item 9 or 10. (12) A signal for driving the rectangular wave generation circuit is formed from a winding provided in the output transformer of the inverter, and
12. The discharge lamp lighting device according to claim 1, wherein a low DC voltage to be supplied to a switching transistor of an inverter is obtained from the winding.