JP2003347082A - Safety circuit for lighting circuit for dielectric barrier discharge lamp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a safety circuit for a lighting circuit for a dielectric barrier discharge lamp capable of preventing a peripheral member from being burned and preventing a human body from receiving an electric shock by detecting a high pressure output waveform of an output transformer of a lighting circuit for a dielectric barrier discharge lamp, comparing the shape of the waveform with that in normal lighting and stopping a circuit operation when an abnormality occurs. <P>SOLUTION: Voltage outputted from a high pressure output terminal of the transformer of the lighting circuit for the dielectric barrier discharge lamp is detected, while being divided. The voltage waveform is compared with a reference waveform in normal registered in advance in a comparator circuit. When the voltage waveform deviates from a set range, an operation of the lighting circuit is stopped. <P>COPYRIGHT: (C)2004,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is suitable as a light source for a backlight of a liquid crystal display device used for a personal computer, a car navigation system, a liquid crystal television, a scanner or the like, or used as a light source for processing by sterilization or ultraviolet rays. And a dielectric barrier discharge lamp.

[0002]

2. Description of the Related Art Conventionally, fluorescent lamps and ultraviolet lamps which do not use mercury which is a harmful substance and have little adverse effect on the environment and whose light output and discharge voltage are hardly influenced by ambient temperature are disclosed in, for example, JP-A-2001-2001. 1436
An internal electrode is provided at one end of the discharge lamp as shown at 62,
A dielectric barrier discharge lamp having an external electrode on the outer surface of a glass tube has been developed.

FIG. 5 shows a configuration example of a conventional dielectric barrier discharge lamp having internal electrodes. Reference numeral 1 denotes a glass tube filled with, for example, xenon gas, which itself is a dielectric for causing a dielectric barrier discharge. 2
Is a phosphor coating formed on the inner surface of the glass tube 1 so that the discharge lamp functions as a fluorescent lamp. 3
Is an internal electrode sealed at one end of the glass tube 1, and a conductive terminal 4 is connected to the internal electrode 3 by means such as welding for conduction with the outside of the tube. Reference numeral 5 denotes an external electrode formed by winding a conductive wire or the like around the outer periphery of the glass tube 1.

The above-mentioned dielectric barrier discharge lamp is, for example, shown in FIG.
The lighting is performed by applying a high-frequency voltage having a voltage waveform as shown in FIG. 7 between the internal electrode 3 and the external electrode 5 by a lighting circuit as shown in FIG. Further, a tube current detection circuit 16 may be added as shown in FIG.

[0005]

However, in the conventional lighting circuit as shown in FIG. 6, an abnormality is detected even if the discharge lamp is damaged or the lead wire connecting the transformer and the dielectric barrier discharge lamp is broken. As a result, the high voltage output is still applied from the output transformer, which may lead to burning of peripheral members or electric shock due to high voltage leakage.

In the case of a dielectric barrier discharge lamp, the external electrodes 5 are often arranged over substantially the entire area of the discharge lamp.
If the lamp is broken near the center of the discharge lamp, an arc discharge or a corona discharge is continuously generated between the internal electrode 3 and the adjacent external electrode 5 through the atmosphere. Therefore, as shown in FIG. In addition, even in a drive circuit system that detects when the tube current is interrupted and stops the circuit operation, the current flowing through arc discharge or corona discharge is detected as the tube current, It is not possible to detect abnormalities that lead to burning and electric shock.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and is intended for use in a case where a dielectric barrier discharge lamp is damaged or a lead wire connecting a transformer and the dielectric barrier discharge lamp is disconnected. When the current is completely interrupted and when arc discharge or corona discharge occurs,
An object of the present invention is to provide a safety circuit having a function of detecting those abnormalities and interrupting the circuit operation.

[0008]

In order to solve the above-mentioned problems, the invention according to claim 1 is to provide at least one end of a glass tube in which xenon, a rare gas such as argon or krypton, or a mixed gas thereof is sealed. A discharge lamp having an internal electrode that is led out and sealed with a conductive terminal to the outside and an external electrode that causes a dielectric barrier discharge using the glass tube as a dielectric on a part of the outer peripheral surface of the glass tube is output. In a dielectric barrier discharge lamp lighting circuit, a high voltage output of a transformer is connected to the internal electrode, the other is grounded, and the other electrode is connected to the external electrode of the dielectric barrier discharge lamp, and is lit with an AC waveform such as a rectangular wave. The high-voltage output waveform of the output transformer of the dielectric barrier discharge lamp lighting circuit is detected, and the waveform shape is compared with that at the time of normal lighting. Characterized in that to stop the circuit operation when an abnormality occurs due to breakage of the lead wires connecting the dielectric barrier discharge lamp.

According to a second aspect of the present invention, in the first aspect of the present invention, the normal lighting and the abnormal occurrence are determined based on the maximum voltage values of the output waveforms during the normal lighting and the abnormal occurrence. .

A third aspect of the present invention is characterized in that, in the first aspect of the present invention, normal lighting and abnormal occurrence are determined based on a voltage effective value or an average value of output waveforms during normal lighting and abnormal occurrence. And

According to a fourth aspect of the present invention, in the first, second, and third aspects of the present invention, the dielectric barrier discharge lamp is damaged or the lead wire connecting the transformer and the dielectric barrier discharge lamp is broken. When an occurrence occurs, the output is cut off by stopping the oscillation circuit of the dielectric barrier discharge lamp lighting circuit.

According to a fifth aspect of the present invention, in the first, second and third aspects of the present invention, the dielectric barrier discharge lamp is damaged or the lead wire connecting the transformer and the dielectric barrier discharge lamp is broken. When the occurrence occurs, the output is cut off by a circuit for cutting off the power input.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1, 2, 3, 4, and 5. FIG.

(Embodiment 1) FIG. 1 shows a first embodiment of the present invention.
It is a block diagram of a dielectric barrier discharge lamp lighting circuit according to claim 4. Reference numeral 6 denotes a block showing the configuration of the switching circuit, and reference numeral 7 denotes an oscillation circuit that outputs a signal for controlling the switching circuit 6. Reference numeral 8 denotes a transformer that boosts the power supply voltage by the switching operation of the switching circuit 6 and outputs a high voltage to the load side. Reference numeral 9 denotes a dielectric barrier discharge lamp that is turned on. The dielectric barrier discharge lamp 9 to be turned on here may be a tubular fluorescent lamp as shown in FIG.
Further, it may be deformed into an arbitrary shape, for example, an L shape, or may be a so-called flat plate type. Either the internal electrode 3 or the external electrode 5 may or may not be grounded.

Here, the dielectric barrier discharge lamp is shown in FIG.
Has a length of 150 mm, a tube outer diameter of 3 mm, a cylindrical Ni rod for the internal electrode, and a thickness of 0.3 mm for the external electrode.
A 5 mm Ni lead wire is used, and a rare gas serving as a discharge medium is filled with xenon gas at 13.3 kPa.

The high voltage output terminal 10 of the transformer 8 is connected to the internal electrode 3 and the external electrode 5 is grounded.

At this time, the voltage output from the high voltage output terminal 10 of the transformer 8 is detected while being divided by a voltage detection circuit 11 composed of a resistor or the like, and the detected voltage waveform is registered in a comparison circuit 12 in advance. Is compared with the normal reference waveform. At this time, when the detected voltage waveform deviates from the reference waveform in a predetermined range, a signal to stop the circuit operation is output to the oscillation circuit 7, and the operation of the drive circuit is stopped immediately.

By adopting such a configuration, for example, if an abnormality occurs in the output voltage waveform due to breakage of the dielectric barrier discharge lamp 9 or breakage of the lead wire connecting the transformer 8 and the dielectric barrier discharge lamp 9, In addition, it is possible to stop the operation of the dielectric barrier discharge lamp lighting circuit, and it is possible to prevent high voltage leakage, burning of peripheral components due to arc discharge or corona discharge, and electric shock.

(Embodiment 2) FIG. 2 shows a first embodiment of the present invention.
It is a block diagram showing another example of a dielectric barrier discharge lamp and a dielectric barrier discharge lamp lighting circuit according to claim 5. Reference numeral 6 denotes a block showing the configuration of the switching circuit, and reference numeral 7 denotes an oscillation circuit that outputs a signal for controlling the switching circuit 6. Reference numeral 8 denotes a transformer that boosts the power supply voltage by the switching operation of the switching circuit 6 and outputs a high voltage to the load side. Reference numeral 13 denotes a power supply voltage cutoff circuit that includes transistors and the like and is inserted in series on the power supply line. . Reference numeral 9 denotes a dielectric barrier discharge lamp to be turned on. The dielectric barrier discharge lamp 9 to be turned on here may be a tubular fluorescent lamp as shown in FIG.
For example, it may be an L-shape or a so-called flat plate. Either the internal electrode 3 or the external electrode 5 may or may not be grounded.

Here, the dielectric barrier discharge lamp is shown in FIG.
Has a length of 150 mm, a tube outer diameter of 3 mm, a cylindrical Ni rod for the internal electrode, and a thickness of 0.3 mm for the external electrode.
A 5 mm Ni lead wire is used, and a rare gas serving as a discharge medium is filled with xenon gas at 13.3 kPa.

Further, the high voltage output terminal 10 of the transformer 8 is connected to the internal electrode 3 and the external electrode 5 is grounded.

At this time, the voltage output from the high-voltage output terminal 10 of the transformer 8 is detected while being divided by a voltage detection circuit 11 composed of a resistor or the like, and the detected voltage waveform is registered in the comparison circuit 12 in advance. Is compared with the normal reference waveform. At this time, if the detected voltage waveform deviates from a predetermined range from the reference waveform, a signal to cut off the power supply voltage is output to the power supply voltage cutoff circuit 13 and the dielectric barrier discharge lamp lighting circuit is turned off. Operation is stopped.

By adopting such a configuration, for example, when an abnormality occurs in the output voltage waveform due to breakage of the dielectric barrier discharge lamp 9 or disconnection of the lead wire connecting the transformer 8 and the dielectric barrier discharge lamp 9, it is possible to quickly perform the operation. In addition, it is possible to stop the operation of the dielectric barrier discharge lamp lighting circuit, and it is possible to prevent high voltage leakage, burning of peripheral components due to arc discharge or corona discharge, and electric shock.

(Embodiment 3) FIG. 3 shows a second embodiment of the present invention.
It is a block diagram of a dielectric barrier discharge lamp lighting circuit according to claim 4. Reference numeral 6 denotes a block showing the configuration of the switching circuit, and reference numeral 7 denotes an oscillation circuit that outputs a signal for controlling the switching circuit 6. Reference numeral 8 denotes a transformer that boosts the power supply voltage by the switching operation of the switching circuit 6 and outputs a high voltage to the load side. Reference numeral 9 denotes a dielectric barrier discharge lamp that is turned on. The dielectric barrier discharge lamp 9 to be turned on here may be a tubular fluorescent lamp as shown in FIG.
Further, it may be deformed into an arbitrary shape, for example, an L shape, or may be a so-called flat plate type. Either the internal electrode 3 or the external electrode 5 may or may not be grounded.

Here, the dielectric barrier discharge lamp is shown in FIG.
Has a length of 150 mm, a tube outer diameter of 3 mm, a cylindrical Ni rod for the internal electrode, and a thickness of 0.3 mm for the external electrode.
A 5 mm Ni lead wire is used, and a rare gas serving as a discharge medium is filled with xenon gas at 13.3 kPa.

The high voltage output terminal 10 of the transformer 8 is connected to the internal electrode 3 and the external electrode 5 is grounded.

At this time, the voltage output from the high voltage output terminal 10 of the transformer 8 is detected while being divided by a voltage detection circuit 11 composed of a resistor or the like, and the detected voltage waveform is input to a peak hold circuit 14. , The peak hold circuit 14 inputs the maximum value of the voltage waveform to the comparison circuit 12. The comparison circuit 12 compares the reference voltage corresponding to the maximum value of the voltage waveform in the normal state with the voltage input from the peak hold circuit 14, and stops the circuit operation when the voltage deviates from the reference voltage in a preset range. Is output to the oscillation circuit 7, and the operation of the dielectric barrier discharge lamp lighting circuit is immediately stopped.

With this configuration, if an abnormality occurs in the output voltage waveform due to, for example, breakage of the dielectric barrier discharge lamp 9 or breakage of the lead wire connecting the transformer 8 and the dielectric barrier discharge lamp 9, In addition, it is possible to stop the operation of the dielectric barrier discharge lamp lighting circuit, and it is possible to prevent high voltage leakage, burning of peripheral components due to arc discharge or corona discharge, and electric shock.

(Embodiment 4) FIG. 4 shows a third embodiment of the present invention.
It is a block diagram of a dielectric barrier discharge lamp lighting circuit according to claim 4. Reference numeral 6 denotes a block showing the configuration of the switching circuit, and reference numeral 7 denotes an oscillation circuit that outputs a signal for controlling the switching circuit 6. Reference numeral 8 denotes a transformer that boosts the power supply voltage by the switching operation of the switching circuit 6 and outputs a high voltage to the load side. Reference numeral 9 denotes a dielectric barrier discharge lamp that is turned on. The dielectric barrier discharge lamp 9 to be turned on here may be a tubular fluorescent lamp as shown in FIG.
It may be deformed into an arbitrary shape, for example, an L-shape, or may be a so-called flat type. Either the internal electrode 3 or the external electrode 5 may or may not be grounded.

Here, the dielectric barrier discharge lamp is shown in FIG.
Has a length of 150 mm, a tube outer diameter of 3 mm, a cylindrical Ni rod for the internal electrode, and a thickness of 0.3 mm for the external electrode.
A 5 mm Ni lead wire is used, and a rare gas serving as a discharge medium is filled with xenon gas at 13.3 kPa.

The high voltage output terminal 10 of the transformer 8 is connected to the internal electrode 3 and the external electrode 5 is grounded.

At this time, the voltage output from the high-voltage output terminal 10 of the transformer 8 is detected while being divided by a voltage detection circuit 11 composed of a resistor or the like. The detected voltage waveform is an integration circuit 15 which is a low-pass filter. Is input to The integrating circuit 15 compares the integrated value of the voltage waveform with the comparing circuit 12
To enter. The comparison circuit 12 compares the reference voltage corresponding to the integral value of the voltage waveform at the time of normal operation with the voltage input from the integration circuit 15, and stops the circuit operation if this voltage deviates from the reference voltage in a predetermined range. A signal to that effect is output to the oscillation circuit 7, and the operation of the dielectric barrier discharge lamp lighting circuit is immediately stopped.

With such a configuration, if an abnormality occurs in the output voltage waveform due to, for example, breakage of the dielectric barrier discharge lamp 9 or breakage of a lead wire connecting the transformer 8 and the dielectric barrier discharge lamp 9, the output voltage waveform can be quickly reduced. The operation of the circuit can be stopped in a short time, and it is possible to prevent high voltage leakage, burnout of peripheral components due to arc discharge or corona discharge and electric shock.

[0034]

According to the safety circuit of the dielectric barrier discharge lamp lighting circuit according to the first, second, third and fourth aspects of the present invention, xenon or a rare gas such as argon, krypton or the like is internally provided. At least at one end of the glass tube in which the mixed gas is sealed, an internal electrode that is led out and sealed with a conductive terminal with the outside, and a dielectric barrier discharge is generated on a part of the outer peripheral surface of the glass tube using the glass tube as a dielectric. Connecting the high voltage output of the output transformer of the lighting circuit for lighting the discharge lamp having the external electrode to the internal electrode,
In the dielectric barrier discharge lamp lighting circuit, which is connected to the external electrode of the discharge lamp by grounding the other and is lit with an AC waveform such as a square wave, the dielectric barrier discharge lamp may be damaged, or the transformer and the dielectric barrier discharge lamp may be damaged. If the current is completely interrupted due to a cause such as a broken lead wire, or if arc discharge or corona discharge occurs, these abnormalities are detected and the circuit operation is interrupted, and the surrounding members are burnt. And electric shock to the human body can be prevented.

In the safety circuit of the dielectric barrier discharge lamp lighting circuit according to the fifth aspect, since the power supply itself to the drive circuit can be cut off, the dielectric barrier discharge lamp is turned on due to, for example, a failure of the switching element. Even when the power supply and the ground of the circuit are short-circuited, the operation of the dielectric barrier discharge lamp lighting circuit can be more reliably stopped than when the oscillation circuit is stopped.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a dielectric barrier discharge lamp lighting circuit according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a dielectric barrier discharge lamp lighting circuit according to another example of the first embodiment of the present invention.

FIG. 3 is a block diagram showing a dielectric barrier discharge lamp lighting circuit according to a second embodiment of the present invention.

FIG. 4 is a block diagram showing a dielectric barrier discharge lamp lighting circuit according to a third embodiment of the present invention.

FIG. 5 is a configuration diagram of a general dielectric barrier discharge lamp.

FIG. 6 is a block diagram showing a conventional dielectric barrier discharge lamp lighting circuit.

FIG. 7 is a waveform chart showing an example of a voltage waveform when the dielectric barrier discharge lamp is turned on.

FIG. 8 is a block diagram showing an example of a conventional dielectric barrier discharge lamp lighting circuit to which a tube current detection circuit is added.

FIG. 9 is a waveform chart showing an example of an output voltage waveform when an abnormality occurs.

[Explanation of symbols]

1 Glass tube 2 Phosphor coating 3 internal electrodes 4 Conductive terminals 5 External electrodes 6 Switching circuit 7 Oscillation circuit 8 transformer 9 Dielectric barrier discharge lamp 10 High voltage output terminal 11 Voltage detection circuit 12 Comparison circuit 13 Power supply voltage cutoff circuit 14 Peak hold circuit 15 Integrator 16 Tube current detection circuit 17 Power supply

Claims (5)

[Claims] 1. An internal electrode which is sealed at least at one end of a glass tube in which a rare gas such as xenon, or argon or krypton, or a mixed gas thereof is enclosed. A discharge lamp having an external electrode that causes a dielectric barrier discharge with a glass tube as a dielectric on a part of the outer peripheral surface of the discharge lamp is connected to a high-voltage output of an output transformer to the internal electrode, and the other is grounded to form the dielectric. In the dielectric barrier discharge lamp lighting circuit connected to the external electrode of the barrier discharge lamp and lit with an AC waveform such as a rectangular wave, a high-voltage output waveform of an output transformer of the dielectric barrier discharge lamp lighting circuit is detected. By comparing the shape of the waveform with that at the time of normal lighting, when an abnormality occurs due to breakage of the dielectric barrier discharge lamp, breakage of a lead wire connecting a transformer and the dielectric barrier discharge lamp, or the like. Safety circuit of a dielectric barrier discharge lamp lighting circuit, characterized in that to stop the circuit operation. 2. The safety circuit for a dielectric barrier discharge lamp lighting circuit according to claim 1, wherein normal lighting and abnormal occurrence are determined based on the maximum voltage values of output waveforms during normal lighting and abnormal occurrence. 3. The safety circuit for a dielectric barrier discharge lamp lighting circuit according to claim 1, wherein the normal lighting and the occurrence of an abnormality are determined based on the voltage effective value or the average value of the output waveforms at the time of the normal lighting and the occurrence of the abnormality. 4. An output is cut off by stopping an oscillation circuit of a dielectric barrier discharge lamp lighting circuit when an abnormality occurs due to breakage of a dielectric barrier discharge lamp or breakage of a lead wire connecting a transformer and the dielectric barrier discharge lamp. 4. The safety circuit for a dielectric barrier discharge lamp lighting circuit according to claim 1, wherein the safety circuit performs the following. 5. The circuit according to claim 1, wherein an output is cut off by a circuit for cutting off a power supply input when an abnormality occurs due to breakage of the dielectric barrier discharge lamp or breakage of a lead wire connecting the transformer and the dielectric barrier discharge lamp. The safety circuit for a dielectric barrier discharge lamp lighting circuit according to claim 2.