JPH07263150A - Discharge lamp lighting device - Google Patents

Abstract

PURPOSE:To stop lighting equipment safely and permanently when a lamp does not light normally by detecting the voltage across a smoothing capacitor connected to both ends of a serially connected body, and automatically cutting off a fuse when the detected voltage gets over a specified value so as to stop the supply of power. CONSTITUTION:A protection circuit 10 detects the voltage across the smoothing capacitor 79 connected to both ends of the series body of a discharge lamp lighting equipment, and when the detected voltage gets over the specified value at abnormality, a current flows to a Zener diode 104, and a transistor 105 is turned on. Hereby, part of the base current of the transistor 70 of an inverter circuit 7 is bypassed, and the transistor 70 runs short of a base current and generates heat, and a collector and an emitter get in short circuit condition, and a large current flows, and a fuse 1a connected to an AC power source 1 is automatically fused down, thus a discharge lamp lighting equipment can be stopped safely and permanently when the discharge lamp does not light by the abnormality of the discharge lamp, parts, or the like.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge lamp lighting device.

[0002]

2. Description of the Related Art As a conventional discharge lamp lighting device,
As shown in FIG. 5, the chopper circuit 4 and the inverter circuit 5
It is known that and share a switching element.
As a result, the input power factor of the voltage input to the discharge lamp 6 is increased and the harmonic components are reduced.

A circuit configuration of the above-described conventional discharge lamp lighting device will be described. The inverter circuit 5 includes transistors 50 and 51 connected in series and a transistor 5
Diodes 50 connected in anti-parallel to 0 and 51 respectively
a, 51a and a capacitor 5 connected in parallel
2, 53 series circuit, feedback windings 54c1 and 54c2 for driving the transistors 50 and 51, output winding 54b connected to the discharge lamp 6, connection points of the transistors 50 and 51, and capacitors 52 and 53. A transformer 54 having a primary winding 54a connected between the
5, 56, 57 and 58. Chopper circuit 4
Is a noise filter 2 and a rectifier circuit 3 with respect to the AC power supply 1.
From the smoothing capacitor 41, the transistor 50, the inductance element 42 connected between the transistor 50 and the output terminal of the rectifier circuit 3, and the connection point between the inductance element 42 and the transistor 50. It is composed of a diode 51a for supplying a charging current to the smoothing capacitor 41 (Japanese Patent Laid-Open No. 3-276598).

Next, the operation of the above circuit will be described. When a DC pulsating voltage that is full-wave rectified from the AC power supply 1 via the noise filter 2 and the rectifier circuit 3 is applied to the chopper circuit 4, the smoothing capacitor 41 is connected to the inductance element 42.
And is charged via the diode 51a. For example, resistor 5
A start-up current flows through 6 to turn on the transistor 50. When the transistor 50 turns on, the smoothing capacitor 4
A current flows from 1 through the capacitor 53 and the transformer 54, and the transformer 54 and the capacitor 5 of the inverter circuit 5
The resonance system composed of 2, 53 starts to vibrate. for that reason,
A voltage is generated in the feedback windings 54c1 and 54c2 of the transformer 54 so that the transistor 50 is turned on and the transistor 51 is turned off, the transistor 50 is kept on, and the transistors 50 and 51 are turned on and off in accordance with the vibration of the resonance system. Are repeated alternately. When the transistor 50 is on,
A current limited by the inductance element 42 flows from the AC power supply 1 through the inductance element 42, and this current increases with time. Furthermore, this current, and
A current flowing from the smoothing capacitor 41 via the resonance system simultaneously flows through the transistor 50, and this current increases with time. Next, when the transistor 50 is turned off, the energy stored in the inductance element 42 immediately before turning off is discharged to the smoothing capacitor 41 via the diode 51a. At the same time, when the transistor 50 is turned off, the transistor 51 is turned on, the resonance system continues to vibrate, and the discharge lamp 6 is continuously supplied with voltage and energy. Due to the vibration of the resonance system, the transistor 51 is turned off,
When the transistor 50 is turned on, the chopper circuit 4 is hereafter
The inverter circuit 5 repeats the above operation to keep the discharge lamp 6 lit.

In this operation, when the instantaneous value of the AC power supply 1 is low, the rate of increase of the current flowing through the inductance element 42 is low, and if the on-time is always the same, the transistor 5
The stored energy of the inductance element 42 is small when 0 is off, and the charging voltage of the smoothing capacitor 41 also drops.
At this time, the input current also decreases according to the instantaneous value of the AC power supply 1. When the instantaneous value of the AC power source 1 is high, the operation opposite to that when the instantaneous value is low is performed. That is, if the rate of increase of the current flowing through the inductance element 42 is high and the on-time is always the same, the energy stored in the inductance element 42 when the transistor 50 is off is large and the charging voltage of the smoothing capacitor 41 increases. The input current also increases according to the instantaneous value of the AC power supply 1. Therefore, the AC power supply 1
The input current having a shape substantially similar to the waveform of is obtained, the power input power factor is high, and the harmonic component of the power input current can be reduced.

[0006]

However, in such a conventional discharge lamp lighting device, since the inductance element 42 is required in addition to the transformer 54 of the inverter circuit 5, the entire circuit becomes large. In addition, the inductance element 4
Since the entire voltage of the AC power supply 1 is applied to 2 and it is necessary to limit the voltage to a predetermined input current, the inductance element 42 itself also becomes large and becomes more expensive. The smoothing capacitor 4 is used as the transformer 54 of the inverter circuit 5.
Since the voltage of No. 1 becomes proportional to the voltage of the AC power supply 1, the voltage ripple becomes large, and it is necessary to have a voltage large enough to apply a large resonance voltage for a large moment of this voltage ripple, and the whole circuit becomes large. There was such a problem.

To solve this problem, a series body formed by connecting a resonance capacitor, a discharge lamp, an inductance element and a switch element with a control terminal in series, a smoothing capacitor connected to both ends of the series body, and the inductance element. And a connection point of the switch element, a rectifying means connected between the connection point of the resonance capacitor and the smoothing capacitor, a connection point of the discharge lamp and the inductance element, and a connection point of the smoothing capacitor and the switch element. A discharge lamp with a small and simple structure, a high input power factor, and a low harmonic component of the power input current is provided by providing a rectifier circuit with a rectified output terminal connected to the A discharge lamp lighting device capable of starting and maintaining lighting is conceivable. However, there is a problem that the smoothing capacitor will be damaged when an abnormality occurs in the discharge lamp or parts.

The present invention is capable of safely starting and maintaining the lighting of a discharge lamp with a small and simple structure, a high input power factor, and a state in which there are few harmonic components of a power supply input current. It is an object of the present invention to provide a discharge lamp lighting device provided with a protection circuit that can safely and permanently stop the lighting circuit when the discharge lamp does not normally light due to an abnormality.

[0009]

DISCLOSURE OF THE INVENTION A discharge lamp lighting device according to the present invention comprises a resonance capacitor, a discharge lamp, an inductance element, and a series element formed by connecting a switching element with a control terminal in series. Smoothing capacitor connected, a connection point between the inductance element and the switch element, rectifying means connected between the connection point between the resonance capacitor and the smoothing capacitor, a connection point between the discharge lamp and the inductance element, the smoothing A rectification output terminal is connected between a connection point of the capacitor and the switch element, a rectification circuit to be connected to an AC power supply, voltage detection means for detecting the voltage across the smoothing capacitor, and voltage by the voltage detection means. Switch means for conducting when the detected value exceeds a predetermined value and for making the control terminal of the switch element to the ground potential And it has a configuration in which.

[0010]

With this configuration, when the discharge lamp does not light up normally due to an abnormality in the discharge lamp or parts, the lighting circuit can be safely and permanently stopped.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, a discharge lamp lighting device according to an embodiment of the present invention includes a resonance capacitor 72, a fluorescent lamp 80 serving as a discharge lamp, an inductance element 73, and
The collector-emitter circuits of the transistor 70, which is the first switch element, are sequentially connected in series to form a series body, and a smoothing capacitor is provided between both ends of the series body, that is, one end of the resonance capacitor 72 and the emitter of the transistor. 79 is connected to form a closed circuit. A diode 71a is connected between the connection point between the inductance element 73 and the transistor 70 and the connection point between the resonance capacitor 72 and the smoothing capacitor 79, and the connection point between the fluorescent lamp 80 and the inductance element 73 and the smoothing capacitor 79. The output terminals of the rectifier circuit 3 to be connected to the AC power supply are connected between the connection points of the transistor 70 and the transistor 70, respectively. Further, a voltage detection circuit composed of a series body of a resistor 101 and a resistor 102 connected in parallel with a smoothing capacitor 79, a collector connected to the base of the transistor 70, and an emitter connected to the smoothing capacitor 79 and the resistor 1.
It has a transistor 105 which is a second switch element connected to a connection point with 02. Transistor 105
The bases of Zener diode 103 and diode 10
It is connected to the connection point between the resistor 101 and the resistor 102 via the switch 4.

Next, the circuit configuration of the discharge lamp lighting device according to the embodiment of the present invention will be described. AC power source 1 and smoothing capacitor 79, fluorescent lamp 80, resonance capacitor 72 connected in series between smoothing capacitor 79 and fluorescent lamp 80, and smoothing capacitor 79 and fluorescent lamp 80 were connected in parallel with smoothing capacitor 79. A series circuit of transistors 70 and 71, which are switching elements, and a transistor 70.
The DC input from the smoothing capacitor 79 using the LC resonance generated by the on / off operation of the transistors 70 and 71 that are connected to the fluorescent lamp 80 and connected in series to the fluorescent lamp 80, that is, the resonance generated by the inductance element and the capacitor. Circuit 7 for converting the AC into AC and supplying it to the fluorescent lamp 80, the rectifying circuit 3 for rectifying the AC power supply voltage, the diode 71a as the rectifying means connected between the transistor 70 and the smoothing capacitor 79, and the inverter circuit 7 Transistor 7
Drive control means 9 having a current transformer 74 connected between 0 and 0 and driving and controlling the transistors 70 and 71 by its output; and a filter circuit 2 connected between the inverter circuit 7 and the AC power supply 1. Is equipped with. One of the output ends of the rectifier circuit 3 is connected to the connection point between the fluorescent lamp 80 and the inductance element 73, and the other is connected to the resistor 77b.
Is connected to the emitter of the transistor 70 via. One end of the inductance element 73 is connected to the collector of the transistor 70 via the primary winding 74a of the current transformer. That is, the rectifier circuit 3, the inductance element 73, the primary winding 74a of the current transformer,
The transistor 70 and the resistor 77b form a closed circuit. The inverter circuit 7 includes a transistor 71 having an emitter connected to the resistor 77a and a transistor 70 having an emitter connected to the resistor 77b, and a series circuit is formed. A smoothing capacitor 79 is connected in parallel with the series circuit. Diodes 70a and 71a are respectively connected in anti-parallel to a series circuit composed of resistors 77a and 77b and transistors 70 and 71, and diode 71a is connected in parallel with a capacitor 78. Also, the transistor 71
And a resistor 77a, a series circuit of a resonance capacitor 72, a fluorescent lamp 80, an inductance element 73, and a primary winding 74a of a current transformer is connected in parallel.
In parallel with this, the capacitor 81 is connected via the electrode of the fluorescent lamp 80. Further, the drive control means 9
The resistor 75a is connected between the output terminal of the secondary winding 74b of the current transformer 74 and the base of the transistor 71 whose emitter is connected to the resistor 77a.
A resistor 75b is connected between the output terminal of the next winding 74c and the base of the transistor 70 whose resistor 77b is connected to the emitter. A diode 76a is connected between the base of the transistor 71 and the resistor 77a toward the base, and a diode 76b is connected between the base of the transistor 70 and the resistor 77b toward the base. A series circuit including a resistor 82 and a capacitor 85 is connected in parallel with the capacitor 23 of the filter circuit 2, and the connection point between the resistor 82 and the capacitor 85 and the transistor 70 are connected.
The base is connected via a trigger element 84.
The filter circuit 2 connects the capacitor 21 in parallel to the AC power source 1 via the fuse 1a, and also connects the rectifier circuit 3
The inductance 22 is connected in series to the output end of the diode, and the diode 24 is connected in series to the output end in the forward direction, and between the connection point between the inductance 22 and the diode 24 and the other end of the output end of the rectifier circuit 3. The capacitor 23 is connected. In the protection circuit 10, a series body of a resistor 101 and a resistor 102 is connected in parallel with the smoothing capacitor 79, and
And a resistor 102 are connected to one end of a series body of the Zener diode 103 and the diode 104, and the other end of the series body has a collector connected to the base of the transistor 70 and an emitter connected to the smoothing capacitor 79 and the resistor 77b. Is connected to the base of the transistor 105 connected to the connection point.

Next, the operation of the discharge lamp lighting device according to the embodiment of the present invention will be described. Before starting the fluorescent lamp 80, a pulsating voltage is generated from the AC power supply 1 through the fuse 1a at one output end of the filter circuit 2. The current due to this pulsating voltage flows to the next closed circuit. That is, one output terminal of the rectifier circuit 3 → the inductance element 73 → current transformer 74 → diode 71a → smoothing capacitor 79 → the other output terminal of the rectifier circuit 3 flows, and the smoothing capacitor 79 is charged to the peak value of the power supply voltage. . At the same time, the charging current causes an output to be generated in the secondary winding 74c of the current transformer 74 to supply the base current of the transistor 70. At the same time, when the capacitor 85 is charged through the resistor 82 and its voltage reaches the breakdown voltage of the trigger element 84, the electric charge of the capacitor 85 is supplied to the base of the transistor 70 and the transistor 70 is turned on. When the transistor 70 is turned on, since the initial voltage of the smoothing capacitor 79 is lower than the voltage value of the AC power supply 1, the inductance element 73, the current transformer 74, and the current transformer 74 from the AC power supply 1 via the rectifier circuit 3 and the filter circuit 2 The current flows through the transistor 70 while increasing. Next, when the core of the current transformer 74 is magnetically saturated by the current flowing through the primary winding 74a of the current transformer 74, the output of the secondary winding 74c is lost, and the base current that has been supplied to the transistor 70 cannot be supplied. 70 turns off. The energy stored in the inductance element 73 immediately before the transistor 70 is turned off is discharged to the smoothing capacitor 79 via the current transformer 74 and the diode 71a. Due to this step-up chopper operation, the voltage of the smoothing capacitor 79 becomes higher than the output voltage of the rectifier circuit 3. At the same time, since the current of the inductance element 73 is a current that decreases with time, 2
The output polarities of the secondary windings 74b and 74c are inverted, turning on the transistor 71 and turning off the transistor 70. At this time, a current flows through the transistor 71 due to the capacitor 72 charged by the smoothing capacitor 79. When this current decreases, the trigger element 84
The operation of turns on the transistor 70.

Next, when the transistor 70 is turned on again, the output voltage of the rectifier circuit 3 and the filter circuit 2 is initially lower than the voltage charged in the smoothing capacitor 79 at this time, so the diode 24 is off. The current flowing through the inductance element 73 is from the smoothing capacitor 79 to the resonance capacitor 72, the electrode of the fluorescent lamp 80, the capacitor 81, the inductance element 73, the primary winding 74a of the current transformer 74, the transistor 70, and the resistor 77b.
Is the current that flows through. This current is applied to the fluorescent lamp 8
Flow through the 0 electrode to heat this electrode. As the capacitor 81 is charged with this current, the cathode potential of the diode 24 decreases. When the cathode potential of the diode 24 decreases below the anode potential of the diode 24, the diode 24 turns on and current flows from the AC power supply 1. At this time, since the current flowing through the inductance element 73 tries to maintain continuity and the impedance of the capacitor 81 is sufficiently larger than the input impedance including the filter circuit 2, the current flowing through the inductance element 73 is smoothed rapidly. The current from the capacitor 79 is replaced with the current from the AC power supply 1. That is, the electrodes of the fluorescent lamp 80 are heated during the ON period of the transistor 70 until the current transformer 74 switches at a substantially constant current value to turn off the transistor 70, and the inductance element is provided immediately before the transistor 70 is turned OFF. 73
It is possible to replace most of the current flowing through the electrode current for heating the electrode with the current I2 from the AC power supply 1. Therefore, according to the turning off of the transistor 70, the smoothing capacitor 79 can be boosted to a sufficiently large voltage by the energy accumulated in the inductance element 73. At the same time, during the next ON period of the transistor 71, the inductance element 73 and the capacitors 72 and 81 due to the energy accumulated in the capacitors 72 and 81 generated immediately after the diode 24 is turned off due to the decrease in energy discharge of the inductance element 73. A large voltage is applied to the fluorescent lamp 80 and a large current also flows through the electrodes due to the resonance with. By repeating such operations, the electrode temperature of the fluorescent lamp 80 rises and the fluorescent lamp 80 is turned on.

Next, the circuit operation when the fluorescent lamp 80 is turned on will be described. When the transistor 70 turns on,
At this time, the output voltage of the rectifier circuit 3 and the filter circuit 2 is initially sufficiently lower than the voltage charged in the smoothing capacitor 79, and the voltage of the inductance element 73 becomes higher due to the current flowing from the smoothing capacitor 79. Therefore, the diode 24 is off. That is,
What flows to the inductance element 73 is the smoothing capacitor 79, the resonance capacitor 72, the electrode of the fluorescent lamp 80, the capacitor 81, the electrode of the fluorescent lamp 80, the inductance element 73, the primary winding 74a of the current transformer, the transistor 70, and the resistor 77b. Current I ₁ flowing through
2 (current I ₁ during the period of power supply voltage V ₁ <voltage V ₂ of inductance element 73 in FIG. 2B). This current I ₁ is applied to the resonance capacitor 72 and the inductance element 73.
To form a resonance current with. As the resonance capacitor 72 is charged by this current I _1, the cathode potential of the diode 24 decreases, and when it falls below the instantaneous value of the AC power supply 1 which is the anode potential of the diode 24, the diode 24 turns on and the AC A current I ₂ flows from the power supply 1 to the inductance element 73. At this time, this current I
₂ is a function of the current flowing through the inductance element 73 to maintain continuity, and a power supply side input impedance including the filter circuit 2 with respect to the impedance of the resonance capacitor 72, the fluorescent lamp 80 and the capacitor 81 and the voltage value of the smoothing capacitor 79. and up to a value determined by the ratio of the power supply voltage instantaneous value rapidly changes, the current I ₁ from the smoothing capacitor 79, the current I ₂ from the AC power supply 1
2 (b in FIG. 2B, the current I during the period of the power supply voltage V ₁ > the voltage V ₂ of the inductance element 73).
₂ ). That is, the current of the fluorescent lamp 80 is supplied during the on period of the transistor 70 until the current transformer 74 switches at a substantially constant current value due to magnetic saturation and turns off the transistor 70, and before the transistor 70 is turned off. In addition, the current flowing through the inductance element 73 can be partially replaced with the current I ₂ from the AC power supply 1 in terms of current value. Therefore, transistor 7
In response to the turning off of 0, the smoothing capacitor 7 uses the current I ₂ component of the energy stored in the inductance element 73.
Can replenish 9 energy. Further, the discharge of the fluorescent lamp 80 can be maintained at a constant level by the current I ₁ component flowing at the same time. During the period in which the transistor 70 is off and the transistor 71 is on, the charging current to the smoothing capacitor 79 decreases as the energy discharge of the inductance element 73 decreases, and the resonance between the capacitor 72 and the inductance element 73 is maintained. It is possible to maintain the discharge of the fluorescent lamp 80 at a constant level. Then, by repeating such an operation, the fluorescent lamp 80 can be maintained to be lit and the voltage of the smoothing capacitor 79 can be maintained.

The diode 83 is a fluorescent lamp 80.
Is connected so as to discharge when the transistor 70 is on, so that the voltage of the capacitor 85 does not reach the breakdown voltage of the trigger element 84 when is turned on.

In such a starting / lighting operation, when the instantaneous value of the AC power supply 1 is low (hatched portion in FIG. 2A), the power supply voltage V ₁ <as shown in FIG. 2B. period the voltage V ₂ of the inductance element 73 becomes longer and the period of the current I ₂ flowing from the AC power supply 1 to the inductor 73 is short, and the current I ₂ this current I ₂ is proportional to the power supply input voltage instantaneous value Also becomes smaller. That is, the current I ₁ through the fluorescent lamp 80 by the inverter operation temporally suppresses the current I ₂ flowing from the AC power supply 1 to the inductance element 73 as a chopper operation, and the current I _{1 of the} fluorescent lamp 80. Can be reduced.

On the other hand, when the instantaneous value of the AC power source 1 is high (hatched portion in FIG. 3A), the power source voltage V ₁ > the voltage V ₂ of the inductance element 73, as shown in FIG. 3B. The period is long, the period of the current I ₂ flowing from the AC power source 1 into the inductance element 73 is long, and this current is proportional to the instantaneous value of the power source input voltage, so that the current I ₂ becomes large. That is, in this case, the fluorescent lamp 8 operated by the inverter is operated.
The current I ₁ passing through 0 acts as an AC power source 1 for chopper operation.
Therefore, the rate of suppressing the current I ₂ flowing through the inductance element 73 in terms of current value is small.

In this operation, looking at one cycle of the AC power supply 1, the input current I _s has a shape similar to the waveform V _s of the AC power supply 1 as shown in FIG. The power input power factor is high and the harmonic components of the power input current can be reduced.

Regarding the current I ₁ of the fluorescent lamp 80, when the voltage instantaneous value of the AC power source 1 is low, the resonance current I ₁ is kept large, and when the voltage instantaneous value of the AC power source 1 is high, The resonance current I ₁ is suppressed by the input current I _{2, and} the current I ₁ of the fluorescent lamp 80 becomes almost constant in one cycle of the AC power supply 1 as shown in FIG. Therefore, the ripple of the lamp current becomes small, and in the fluorescent lamp 80, the almost constant tube wall load can be applied, so that the instantaneous overload of the phosphor, the electrode and the tube wall can be reduced, and the lamp life can be improved. Further, since the lamp current ripple is small, the electrostatic capacity of the smoothing capacitor 79 can be reduced and the stability of the inverter circuit 7 against the power supply voltage and the load can be improved. Further, as shown in FIG. 4C, the current flowing through the inductance element 73 is the current I ₂ from the AC power source 1 (FIG. 4A) and the current I ₁ from the smoothing capacitor 79 (FIG. 4B). ) And will be added. Current flowing through the inductance element 73 is divided and operates as the current I ₁ from the current I ₂ and the smoothing capacitor 79 some time, and mutually partially current suppressed from the AC power supply 1 As a result, it is possible to provide the same performance as the conventional one with two inductance elements, one for the chopper circuit and the other for the inverter circuit, with the single inductance element. Does not need to be limited by a single inductance component, the inductance value of the inductance element 73 can be set smaller than in the past, so that the size of the inductance element 73 does not increase, and the circuit configuration can be realized easily, inexpensively, and in a small size.

Further, the AC power source 1 to the current transformer 7
Since the smoothing capacitor 79 can be charged first via 4, it is possible to easily turn on the transistor 70 for the first time, and particularly to improve the circuit starting performance at a low temperature.

As described above, in the discharge lamp lighting device according to the embodiment of the present invention, the fluorescent lamp 80, the resonance capacitor 72, the smoothing capacitor 79, the inductance element 73, and the transistor 70 constitute a closed circuit, and the rectifying circuit 3 and the inverter. By forming a closed circuit with the inductance element 73 of the circuit 7 and the transistor 70, the inductance element 7
3 is used for the chopper operation and the inverter operation for a part of the time and a part of the current value so that both the charging operation of the smoothing capacitor 79 and the fluorescent lamp lighting operation interfere with each other. At that time, the current due to the inverter operation works in the direction of suppressing the power supply input current proportional to the instantaneous value of the power supply voltage flowing through the inductance element 73 as the chopper operation.
At the same time, since the current due to the chopper operation is proportional to the instantaneous value of the power supply input voltage, it suppresses the low-frequency ripple of the discharge lamp current flowing through the inductance element 73 and acts as a current suppression element for the discharge lamp current itself. It will be.

As described above, the charging operation of the smoothing capacitor 73 and the lighting operation of the discharge lamp are mutually assisted, the load on the inductance element 73 is reduced, the power input power factor is high, and the harmonic components of the power input current are small. The state can be improved, and the current ripple of the discharge lamp 80 can be improved.

Next, the operation of the protection circuit will be described.
A resonance capacitor, a discharge lamp, an inductance element, and a series body formed by connecting a switching element with a control terminal in series, a smoothing capacitor connected to both ends of the series body, a connection point of the inductance element and the switch element, Rectification means connected between the resonance capacitor and the connection point of the smoothing capacitor, a connection point between the discharge lamp and the inductance element, and a rectification output end is connected between the connection point between the smoothing capacitor and the switch element, A fluorescent lamp device equipped with a rectifier circuit to be connected to an AC power source is provided with a discharge lamp 8 due to an abnormality in the discharge lamp or parts.
When 0 does not light up normally, the input power is not consumed by the fluorescent lamp, so the voltage of the smoothing capacitor 79 rises from that during normal lighting due to the chopper operation described above. At this time, the resistors 101 and 102 of the protection circuit 10
When the voltage detected by the voltage detection circuit including the above exceeds the predetermined breakdown voltage of the Zener diode 104, a current flows through the Zener diode 104 and the transistor 10
5 bases. As a result, the transistor 10
Since the collector and the emitter of No. 5 are electrically connected and a part of the base current of the transistor 70 is bypassed, the transistor 70 has a shortage of the base current and heat is generated, and the collector-emitter short-circuit occurs and a large current flows and the fuse 1
a momentarily breaks. In a state after such a protection circuit operates, even if the AC power supply 1 is released and reconnected, the discharge lamp 8
0 does not light. And the circuit is also stopped.

As described above, in the discharge lamp lighting device of the present invention, the protection circuit 10 can safely and permanently stop the discharge lamp lighting device when an abnormality occurs in the discharge lamp or parts. Further, by setting the detection voltage of the voltage detection circuit to be equal to or higher than the voltage of the electrolytic capacitor when the lamp is started and equal to or lower than the voltage when the discharge lamp is abnormal or the parts are abnormal, damage to the electrolytic capacitor can be reduced.

As an example, in the circuit configuration shown in FIG. 1, the inductance element 73 is 1.2 mH, the resonance capacitor 72 is 0.022 μF, and the capacitor 81 is 2200.
pF smoothing capacitor 79 is 10 μF, AC power supply voltage 12
Experiments using 0V each show 15W normally
TOTAL HARM is a total of harmonics with respect to the fundamental wave, which can start and maintain the lighting of the fluorescent lamp at 99%.
In the lighting circuit where the good result that the ONIC DISTORTION is 10% or less is obtained, the resistance 101 is 4
When the resistance was 70 kΩ, the resistance 102 was 6.8 kΩ, and the Zener diode was 5.6 V, the fuse was cut off and operated safely in the abnormal state.

In the above embodiment, the drive control means 9 can be made the smallest in circuit, so the self-excitation method using the current transformer 74 is used, but other methods can also be used effectively. Further, although the switching elements 70, 71, 105 are bipolar transistors, FETs or the like are also effective. In this case, the same applies to the case where the diodes 71a and 70a have a built-in FET. Also in the case of this embodiment, the bases of the transistors 71 and 70 are
The same applies to the case where the collector-to-collector PN junction is the diodes 71a and 70a. Further, in the present embodiment, the series inverter is used as the inverter circuit configuration, but the same effect can be obtained with any other inverter circuit using resonance, and the same effect can be obtained with the single-stone inverter circuit.

[0029]

As described above, in the discharge lamp lighting device of the present invention, the resonance capacitor, the discharge lamp, the inductance element, and the switch element with the control terminal are connected in series, and the series body of the series body is formed. Smoothing capacitors connected to both ends, a connection point between the inductance element and the switch element, rectifying means connected between the connection point between the resonance capacitor and the smoothing capacitor, a connection point between the discharge lamp and the inductance element, A rectifying output terminal is connected between the connection points of the smoothing capacitor and the switch element, a rectifying circuit to be connected to an AC power source, voltage detection means for detecting the voltage across the smoothing capacitor,
And, by providing the switch means for conducting when the voltage detection value by the voltage detection means exceeds a predetermined value to bring the control terminal of the switch element to the ground potential, a small size,
With an inexpensive and simple configuration, the power supply input power factor is high, and the discharge lamp can be started and maintained in the state where there are few harmonic components of the power supply input current. When the discharge lamp does not light, the discharge lamp lighting device can be stopped safely and permanently.

[Brief description of drawings]

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

FIG. 2A is a waveform diagram of current and voltage. FIG. 2B is a waveform diagram of current and voltage of an inductance element when the instantaneous value of the AC power supply voltage is low.

FIG. 3A is a waveform diagram of a power supply voltage. FIG. 3B is a waveform diagram of an inductance element current voltage when the AC power supply voltage instantaneous value is high.

[Fig. 4] Input current / lamp current / inductance element current waveform diagram for one cycle of the AC power supply

FIG. 5 is a circuit diagram of a conventional discharge lamp lighting device.

[Explanation of symbols]

 1 AC power supply 3 Rectifier circuit 70, 71 Transistor 72 Resonant capacitor 73 Inductance element 79 Smoothing capacitor

Claims (1)

[Claims] 1. A series body formed by connecting a resonance capacitor, a discharge lamp, an inductance element and a switch element with a control terminal in series, a smoothing capacitor connected to both ends of the series body, the inductance element and the switch element. A rectifying means connected between the resonance capacitor and the smoothing capacitor, a rectifying output terminal between the discharge lamp and the inductance element, and a connection point between the smoothing capacitor and the switch element. A rectifier circuit to be connected to an AC power source, a voltage detecting means for detecting the voltage across the smoothing capacitor,
And a discharge lamp lighting device comprising switch means which is conductive when a voltage detection value detected by the voltage detection means exceeds a predetermined value so that the control terminal of the switch element is set to the ground potential.