JPH10199693A - Lighting equipment for discharge lamp and lighting equipment in discharge lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To apply a suitable voltage at a start by providing an inverter which energizes a discharge lamp by generating a high frequency output from a direct current output of a booster chopper, and by changing an operation of a switching device so as to start the discharge lamp. SOLUTION: A capacitor C83 is charged by the direct current output of a voltage doubler rectifier circuit 8a, and when its terminal voltage exceeds the Zener voltage of a Zener diode ZD81, the diode ZD81 and a transistor Q82 is turned on, and a transistor Q81 is turned off. Then a transistor QCP start on/off according to on/off of a transistor Q41. Then a booster chopper circuit 4 starts to operate, and boosts the intput voltage of an inverter 5 up to a given value. Accordingly, the output voltage of the circuit 5 increases, and a fluorescent lamp begins to discharge. After the beginning of discharge, a capacitor C2 is substantially closed by discharging path of the lamp, the load current becomes stable, and a normal lighting is attained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lighting device for a discharge lamp which includes a step-up chopper and an inverter, generates high-frequency power from a low-frequency AC power supply such as a commercial power supply or a DC power supply, and energizes the discharge lamp. And a discharge lamp lighting device.

[0002]

2. Description of the Related Art In many cases, a large number of discharge lamp lighting devices are installed and used in a facility such as a building. When the circuit power factor of each discharge lamp lighting device is low, a large amount of reactive power is generated in the entire facility. Is generated, and the occurrence of harmonic distortion may be conspicuous. To improve this,
In recent years, chopper circuits have been used in various discharge lamp lighting devices, including those used in facilities.

In addition, discharge lamps such as fluorescent lamps and high-pressure discharge lamps repeatedly blink at the end of their service life due to the deterioration of electrodes in accordance with the lighting time, or the lamp voltage of the discharge lamp rises abnormally. There are specific phenomena that occur. For this reason, in the discharge lamp lighting device, in order to eliminate discomfort caused by blinking of the discharge lamp, and to suppress electric stress on circuit components due to intermittent output of high voltage, When an abnormal state such as opening or short-circuiting of the load occurs, a function of reducing the output V20 or a function of reducing the short-circuit current I2S may be added. The one to which such a function is added also has an advantage that the occurrence of electric shock during lamp replacement work can be reduced for a discharge lamp lighting device in which the lamp is often replaced while the power is on. Will be.

For example, Japanese Patent Application Laid-Open No. 56-136498 discloses that the operation of the chopper and the inverter is started after a certain period of time has passed since the power was turned on. A discharge lamp lighting device is described in which a control circuit for controlling a chopper operates intermittently.

[0005] This kind of discharge lamp lighting device is provided with a soft start function for starting the discharge lamp after sufficiently preheating the electrodes when starting the discharge lamp, as disclosed in Japanese Patent Application Laid-Open No. 55-105996, for example. Or, for example,
As disclosed in Japanese Patent Application Laid-Open No. 9-180993, there is a device in which the output is controlled so as to reliably generate an arc discharge.

[0006]

However, in the prior art, in order to realize control at the time of starting the discharge lamp,
It is necessary to add a dedicated switch element such as a transistor or a thyristor for switching control to the inverter circuit, and it has been difficult to simplify the circuit configuration.

SUMMARY OF THE INVENTION An object of the present invention is to provide a lighting device for a discharge lamp and a lighting device for a discharge lamp which can realize the control required at the time of starting the discharge lamp with a simple circuit configuration.

[0008]

According to a first aspect of the present invention, there is provided a lighting device for a discharge lamp, comprising: a DC power supply; a step-up chopper to which the DC power is input; and a high-frequency output from the DC output of the step-up chopper. , And means for changing the operation of the switching device of the step-up chopper so as to start the discharge lamp.

Here, the DC power supply may be, for example, one that rectifies the input of a commercial low-frequency AC, smoothes it as necessary, and outputs DC. The inverter may be of any type as long as it has a function of inputting a direct current and outputting an alternating current, preferably several kHz, and more preferably a high frequency of 20 kHz or more that is higher than an audible frequency. Allow inverter. The means for changing the operation of the switching device of the step-up chopper means a device capable of changing the operation by controlling the opening / closing operation frequency, on / off width, and the like of the switch element performing the chopper operation. The discharge lamp may be an existing high-pressure discharge lamp in addition to a low-pressure mercury-vapor discharge lamp such as a fluorescent lamp using mercury vapor as a light emitting source.

A lighting device for a discharge lamp according to a second aspect of the present invention includes, in addition to the lighting device for a discharge lamp according to the first aspect, a discharge lamp energized by the lighting device.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a circuit configuration of a lighting device for a discharge lamp according to a first embodiment of the present invention. The apparatus shown in FIG. 1 converts an AC input input from an AC power supply 1 into a pulsating current output by a rectifier circuit 3 (converts it into a direct current), and flattens or smoothes the pulsating current output by a step-up chopper circuit 4 to output. This is converted into a high-frequency current by a series inverter circuit 5 comprising SEPP switching transistors Q1a and Q1b, and the fluorescent lamp F connected to the output terminal 6 is turned on.

The chopper circuit 4 includes an inductor Lcp and a diode Dcp connected in series between a positive output terminal of the rectifier circuit 3 and a positive input terminal of the inverter circuit 5, and a smoothing capacitor connected in parallel to the output terminal. Ccp, MOS type field effect transistor Qcp and the like. The capacitors C81 and C82 and the diodes D81 and D82 constitute a voltage doubler rectifier circuit 8a, which doubles and rectifies a high frequency voltage generated in a secondary winding W2b of a current transformer T2 of the inverter circuit 5 described later. This rectified output is applied to the gate of the transistor Qcp via the resistors R41 and R42. The gate of the transistor Qcp is connected to the collector of the transistor Q41 via a diode D43. The base of the transistor Q41 is a resistor R43 and a Zener diode Z.
The transistors Q1a and Q1 of the inverter circuit 5 are connected via D41.
Connected to connection point 1b.

The chopper circuit 4 includes an inverter circuit 5
Generates a high-frequency output, the transistor Qcp is DC-driven by the above-described voltage-doubled rectified output to turn on the transistor Qcp, and for each cycle of the high-frequency output of the inverter circuit 5, the output voltage exceeds the zener voltage of the zener diode ZD41. By turning on the transistor Q41, the transistor Qcp is turned off. As a result, the transistor Qcp turns on and off in synchronization with the oscillation frequency of the inverter circuit 5.
When the transistor Qcp turns on, the inductor Lcp is energized and electromagnetic energy is stored. Next, when the transistor Qcp is turned off, the electromagnetic energy stored in the inductor Lcp is changed to the inductor Lcp, the diode Dcp,
It is released through the path of the inverter circuit 5 and the rectifier circuit 3. The capacitor Ccp smoothes the current supplied to the inverter circuit 6. This output current is determined mainly by the on-duty of the transistor Qcp of the chopper circuit 4, and hardly depends on the output voltage of the rectifier circuit 3. Moreover,
If the output voltage of the inverter circuit 5 is high, the on-period of the Zener diode ZD41 and the transistor Q41 becomes longer, and the on-duty of the transistor Qcp becomes smaller. Conversely, if the output voltage of the inverter circuit 5 is low, the on duty of the transistor Qcp increases. For this reason, the charging current to the smoothing capacitor Qcp is stabilized to some extent, and the smoothness of the DC output to the inverter circuit 5 is increased.
In addition, the power factor from the AC power supply 7 to the rectifier circuit 3 can be increased.

In the inverter circuit 5, T2 is a saturable feedback transformer having one primary winding W21 and two secondary windings W2a and W2b having opposite windings. The primary winding W21 is inserted in series with the output terminal 6, detects a load current flowing therethrough, and generates secondary voltages of opposite phases corresponding to the secondary windings W2a and W2b. Secondary winding W2a
Is connected to the input terminal of the base drive circuit 5a of the switching transistor Q1a, and the output terminal of the base drive circuit 5a is connected to the base of the switching transistor Q1a. Similarly, the secondary winding W2b is connected to the base of the switching transistor Q1b via the base drive circuit 5b.

The fluorescent lamp F is connected between an output terminal 6 of the inverter circuit 5 and a DC output terminal of the chopper circuit 4 via a choke coil CH which is a current limiting element.

In this device, further, a series circuit from the positive DC output terminal of the chopper circuit 4 to the negative DC output terminal of the chopper circuit 4 via the resistor R1 and the capacitor C1, a resistor R1 and a capacitor C7, A relaxation oscillation circuit composed of a connection point J and a unidirectional thyristor SS connected in series to the base of one switching transistor Q1b forms a starting circuit of the inverter circuit 5. The connection point J and the switching transistor Q1b
Diode D1 connected between the collector of
Is for keeping the charging voltage of the capacitor C1 below the breakover voltage of the bidirectional thyristor SS after starting the inverter, stopping the operation of the starting circuit, and preventing the inverter from malfunctioning.

When the AC power supply 1 is turned on in the apparatus shown in FIG. 1, a rectified output is generated from the rectifier circuit 3. This output is the inductor Lcp and the capacitor Ccp of the chopper circuit 4.
A DC voltage having a peak value of the AC power supply voltage is generated at the output terminal of the chopper circuit 4. As a result, charge starts to be accumulated in the capacitor C1 via the resistor R1. When the potential at the connection point J exceeds the breakover voltage of the bidirectional thyristor SS, the thyristor SS conducts and supplies a base current to the switching transistor Q1b on one side. Further, a current is supplied to the collector of Q1b from the connection point J via the diode D1, so that Q1b is turned on,
The inverter circuit 5 is activated and starts oscillating.

During this time, it goes without saying that a part of the load current is positively fed back by the transformer T2, and the switching transistors Q1a and Q1b are alternately turned on and off by their base drive circuits 5a and 5b. Oscillation continues.

Immediately after the start, the fluorescent lamp F has not reached the dischargeable state.
H and the series resonance circuit of the starting capacitor C2 connected between both filaments of the fluorescent lamp F are connected. Since the Q of this resonance system is high, the load current is larger than that in normal lighting. It has become. When the inverter circuit 5 starts oscillating and a load current flows, the chopper circuit 4 operates as described above to boost and smooth the output of the rectifier circuit 3.

Next, the chopper output control circuit 8 will be described.
The output control circuit 8 reduces the output of the inverter circuit 5 during a certain period by delaying the boosting operation of the chopper circuit 4 until a certain time has elapsed after the activation of the inverter circuit 5, thereby completing the warm-up of the fluorescent lamp F. It has a function to prevent a so-called cold start in which discharge is started before. Further, in the present embodiment, the chopper operation is stopped by detecting the no load and the load short circuit and turning off the transistor Qcp, thereby reducing the DC output of the chopper circuit 4 and reducing the high frequency output of the inverter circuit 5. It also does. That is, the AC power supply 1
Is turned on and the inverter circuit 5 is started, a high-frequency voltage is generated in the secondary winding W2b of the transformer T2. This voltage is converted to a DC output by the voltage doubler rectifier circuit 8a. When this DC output is generated, the chopper output control circuit 8 operates, but after the power is turned on, the charge of the capacitor C83 is zero and the terminal voltage is also zero. Therefore, the Zener diode ZD81 and the transistor Q82 are turned off, the transistor Q81 is turned on and the transistor Qcp is turned off, and the step-up chopper does not perform the step-up operation. Therefore, the output of the chopper and the output of the inverter circuit 5 are low. Next, the voltage doubler rectifier circuit 8
When the capacitor C83 is charged via the resistor R81 by the DC output of a, and its terminal voltage exceeds the Zener voltage of the Zener diode ZD81, the Zener diode ZD81 turns on, the transistor Q82 turns on, and the transistor Q81 turns on.
Turns off. As a result, the transistor Qcp starts on / off in accordance with the on / off of the transistor Q41.
Here, the rising chopper circuit 4 operates for the first time, and the input voltage of the inverter circuit 5 is boosted to a predetermined voltage. As a result, the output voltage of the inverter circuit 5 increases, and a voltage sufficiently higher than the discharge start voltage is applied between the two filaments to start the discharge of the fluorescent lamp F. After the start of the discharge, the capacitor C2 is substantially closed by the lamp discharge path, so that the load current is stabilized and the lighting state is normal.

When the fluorescent lamp F is detached, or when no load occurs, such as when discharge does not normally occur with the life of the discharge lamp, the series connection of the choke coil CH and the capacitor C2. The load current increases due to resonance,
The voltage of the secondary winding W2a of the transformer T2 increases. Therefore, when the output voltage of the voltage doubler rectifier circuit 8a rises and this state continues for a set time or more, the terminal voltage of the capacitor C84 charged via the resistor R82 exceeds the zener voltage of the zener diode ZD82. As a result, the Zener diode ZD82 and the transistor Q83 are turned on, the transistor Q82 is turned off, the transistor Q81 is turned on, the transistor Qcp is turned off, and the boosting operation of the chopper circuit 4 is stopped. Is reduced.

When the fluorescent lamp F is short-circuited and does not turn on normally, that is, when the load is short-circuited, the inverter circuit 5 becomes an inductive load and the load current decreases, so that the voltage of the secondary winding W2b of the transformer T2 is reduced. Goes down. As a result, the output of the voltage doubler rectifier circuit 8a decreases, the Zener diode ZD83 turns off, and the transistor Q83 turns on. If the output voltage of the voltage doubler rectifier circuit 8a is equal to or higher than a predetermined value, the rectifier circuit 8a outputs the transistor Q83 via the transistor Q84, the resistor R83 and the Zener diode ZD84.
Is turned on, and thereafter, as in the case of no load, the transistor Qcp is turned off, and the boosting operation of the chopper circuit 4 is stopped.
The input voltage of the inverter circuit 5 decreases. Note that the chopper output control circuit 8 may reduce the output of the chopper circuit 4 by changing the switching frequency, the on-duty, and the like of the transistor Qcp that performs the chopper operation when the no-load and the load short-circuit are detected. .

FIG. 2 is a partial circuit diagram of a discharge lamp lighting device according to another embodiment of the present invention. Note that, in FIG. 2, the same or corresponding parts as those in the apparatus of FIG. 1 are denoted by the same reference symbols. FIG. 2 shows a boost chopper circuit using a saturable current transformer. The boost chopper output control circuit shown in FIG. It is connected to a circuit for stopping the boosting function. In this case, the inverter may be a series inverter or the like, through which a large resonant current flows without load, or an inverter type may be used, but an inverter whose output is a leakage transformer can be applied. When the output is a leakage transformer, the input end of the detection part of the circuit is connected from the terminals d and e in FIG. 3 to the terminals d and e in FIG. 2, for example, as shown in FIG. The operation is the same as in FIG.

As described above, according to the present invention, in the combination of the step-up type chopper and the inverter type discharge lamp lighting device, by controlling the chopper when the discharge lamp is started, a voltage suitable for starting the discharge lamp is applied to the discharge lamp. can do.
Further, if necessary, when the discharge lamp is not lit normally, the load short-circuit current I2s and the no-load voltage V20 can be reduced.

In the above embodiment, a self-excited type inverter is used. However, any type of inverter, such as a separately-excited type inverter or a constant current type inverter using an output transformer, may be used. You may.

[0027]

As described above, according to the present invention, by changing the operation of the switching device of the step-up chopper, a voltage suitable for starting the discharge lamp is applied to the discharge lamp without adding a dedicated switch or the like. can do. Furthermore, if necessary, the output of the chopper can be reduced when the discharge lamp does not light up normally.For example, lighting for discharge lamps with an output reduction function when there is no load or a current reduction function when the load is short-circuited A device and a discharge lamp lighting device can also be realized.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a discharge lamp lighting device according to a first embodiment of the present invention.

FIG. 2 is a partial circuit diagram showing a main part of a discharge lamp lighting device according to a second embodiment of the present invention.

FIG. 3 is a partial circuit diagram showing a connection example of a circuit for detecting no load from the output of the leakage transformer in FIG. 2;

[Explanation of symbols]

1: AC power supply, 3: Rectifier circuit, 4: Boost chopper circuit, 5: Inverter circuit, 6: Output terminal, Ccp: Smoothing capacitor, Qcp: Chopper transistor Lcp: Inductor, Dcp, Drs: Diode, Q1a, Q
1b: Switching transistor, Q81-84: Transistor, ZD81-83: Zener diode, C83, C84, C
ss: capacitor, R81, R82, Rss: resistance, T1: saturable current transformer, T3: transformer, W1t: trigger winding, W1c: collector winding, W1b: base driving winding

Claims (2)

[Claims] A step-up chopper that receives the DC power as an input; an inverter that generates a high-frequency output from the DC output of the step-up chopper to energize the discharge lamp; and a step-up type that starts the discharge lamp. Means for changing the operation of the switching device of the chopper; and a lighting device for a discharge lamp. 2. A discharge lamp lighting device comprising: the discharge lamp lighting device according to claim 1; and a discharge lamp energized by an inverter.