JPH07220883A - Discharge lamp lighting device - Google Patents

Abstract

PURPOSE:To detect the removal of a discharge lamp in a short time without using a high-withstand voltage, high-capacity capacitor for cutting off a DC current in a discharge lamp fitting detecting circuit. CONSTITUTION:This discharge lamp lighting device is provided with a preheating coil 28 generating the electric power for preheating filaments 29b, 30b connected to two discharge lamps 29, 30 connected in series and a diode bridge circuit 32 rectifying the AC current outputted from the preheating coil 28. The capacitor 33 for starting serial lighting is connected in parallel with the first discharge lamp 29 connected to the positive electrode side of a DC power source 21.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION This invention relates to two serially connected devices.
The present invention relates to a discharge lamp lighting device that controls lighting of a discharge lamp of a book.

[0002]

2. Description of the Related Art FIG. 4 shows a circuit diagram of an example of a conventional discharge lamp lighting device.

A DC power supply 1 for obtaining a DC current by rectifying and smoothing the AC current supplied from a commercial AC power supply is connected to a series circuit including a resonance coil 2 and an NPN type first transistor 3. There is. That is, one end of the resonance coil 2 is connected to the positive electrode side of the DC power supply 1, and the other end of the resonance coil 2 is connected to the collector terminal of the first transistor 3. The emitter terminal of the first transistor 3 is connected to the negative side (ground) of the DC power supply 1.

A first capacitor 4 for resonance is connected in parallel to the resonance coil 2, and a base terminal of the first transistor 3 is connected to a positive electrode side of the DC power source 1 via a first resistor 5. It is also connected to a control circuit 6 that controls the ON / OFF of the first transistor 3.

The connection point between the resonance coil 2 and the collector terminal of the first transistor 3 is connected to one end of a ballast choke 7. The ballast choke 7 is provided with a preheating coil 8 for converting magnetic energy generated by a high frequency current flowing through the ballast choke 7 into electric energy.

A series circuit composed of a first discharge lamp 9 and a second discharge lamp 10 is connected between the positive electrode side of the DC power source 1 and the other end of the ballast choke 7.

That is, on the positive electrode side of the DC power supply 1,
One end of the first filament 9a of the first discharge lamp 9 is connected, and the other end of the ballast choke 7 is connected to one end of the first filament 10a of the second discharge lamp 10. A second condenser 11 for preheating start is connected between the other end of the first filament 9a of the first discharge lamp 9 and the other end of the first filament 10a of the second discharge lamp 10. Has been done.

Both ends of the preheating coil 8 are connected between one end of the second filament 9b of the first discharge lamp 9 and one end of the second filament 10b of the second discharge lamp 10. ing. Further, the other end of the second filament 9b of the first discharge lamp 9 and the second end of the second discharge lamp 10 are
Is connected to the other end of the filament 10b.

The method of connecting the preheating coil 8 between the second filament 9b of the first discharge lamp 9 and the second filament 10b of the second discharge lamp 10 is as described above. In addition to the method of connecting in series, there is a method of connecting in parallel as shown in FIG. That is, one end of each of the second filaments 9b of the first discharge lamp 9 is connected to the second filament 1 of the second discharge lamp 10, respectively.
0b is connected directly to each end, and both ends of the preheating coil 8 are connected to each connection point between the second filaments 9b and 10b.

Further, between the one end of the first filament 10a and the one end of the second filament 10b of the second discharge lamp 10, a third capacitor 1 for starting the series lighting is provided.
2 is connected.

In the conventional example having such a configuration, the control circuit 6
As a result, the first transistor 3 is on / off controlled, and a high frequency current is generated by the action of the first capacitor 4 and the resonance coil 2. The generated high frequency current is limited to an optimum amount of current by the ballast choke 7 and is supplied to the series circuit including the first discharge lamp 9 and the second discharge lamp 10.

At this time, the magnetic energy generated in the ballast choke 7 is converted into electric energy, that is, current by the preheating coil 8, and each second filament of the first discharge lamp 9 and the second discharge lamp 10 is converted. 9b and 10b
And is preheated.

First, the voltage necessary for lighting the first discharge lamp 9 is applied to the first discharge lamp 9 by the third capacitor 12, and the first discharge lamp 9 is lit. The voltage necessary for lighting is applied to the second discharge lamp 10 and the second discharge lamp 10 is lit.

By the way, the emitter (thermoelectron emitting substance) applied to the filaments on both sides of the discharge lamp is applied, and the emitter of the filament on one side scatters or evaporates due to repeated lighting / extinction or long-time lighting. It disappears, electrons are not emitted, and in one side emitter state,
When the electrons are emitted only to one side and the vicinity of the filament on one side is blackened, good lighting cannot be obtained, which is the life of the discharge lamp.

Therefore, it is known that a circuit of a conventional discharge lamp lighting device is further provided with a circuit considering the life of the discharge lamp, as shown in FIG. In FIG. 6, the same members as those in FIG. 4 are designated by the same reference numerals, and the description thereof will be omitted.

The base terminal of the first transistor 3
A safety circuit 13 is connected between the emitter terminals,
This safety circuit 13 is provided for the first discharge lamp 9 or the second discharge lamp 9.
When at least one of the discharge lamps 10 has reached the end of its life, the base terminal and the emitter terminal of the first transistor 3 are short-circuited to stop the oscillation of the first transistor 3 and the first transistor 3 and the Resonance coil 2
Protect the inverter circuit consisting of The safety circuit 1
The short circuit between the base terminal and the emitter terminal of the first transistor 3 due to the protection operation of 3 is held until the discharge lamp is replaced.

In order to release (reset) the short circuit between the base terminal and the emitter terminal of the first transistor 3 by the safety circuit 13, a discharge lamp mounting detection circuit 14 for detecting whether or not a discharge lamp is mounted is provided. ing.

That is, this discharge lamp mounting detection circuit 14
Is a second resistor 14a connected between the positive electrode side of the DC power supply 1 and one end of the second filament 9b of the first discharge lamp 9, and the second resistor 14a of the second discharge lamp 10. A series circuit including a third resistor 14b and a fourth resistor 14c connected between one end of the filament 10b and the negative electrode side of the DC power source 1, and a series circuit connected in parallel with the fourth resistor 14c. No. 4 capacitor 14d, a connection point between the second resistor 14a and the second filament 9b of the first discharge lamp 9 and one end of the preheating coil 8 for cutting a direct current. It is composed of a fifth capacitor 14e.

Therefore, the DC current supplied from the DC power supply 1 passes through the second resistor 14a and the second filament 9b of the first discharge lamp 9 and the second filament 9b of the second discharge lamp 10. Flowing in the filament 10b and charging the fifth capacitor 14e. The direct current flowing through the second filament 10b of the second discharge lamp 9 is supplied to the parallel circuit including the fourth resistor 14c and the fourth capacitor 14d via the third resistor 14b. To be done.

At this time, the mounting states of the first discharge lamp 9 and the second discharge lamp 10 can be determined from the voltage generated across the fourth capacitor 14d. When both the first discharge lamp 9 and the second discharge lamp 10 are mounted, a series circuit including the second resistor 14a and the third resistor 14b and the fourth resistor 14c are connected. The voltage level divided by the serial voltage dividing circuit is formed across the fourth capacitor 14d. When at least one of the first discharge lamp 9 and the second discharge lamp 10 is removed, the second filament 9b of the second discharge lamp 9 is removed.
Alternatively, since at least one of 10b disappears, the direct current flowing through the second resistor 14a is the fifth capacitor 14e.
And, via the preheating coil 8, it is supplied to a parallel circuit including the third resistor 14b and the fourth resistor 14c and the fourth capacitor 14d, and the fifth capacitor 14
When e is charged, the charge level at both ends of the fourth capacitor 14d drops, and it can be detected that the discharge lamp is removed.

The second resistor 14a and the third resistor 14a
The resistor 14b of is generally used to minimize the loss.
Those with a relatively high resistance value (eg several tens of kΩ to several hundreds
kΩ order) is used.

FIG. 7 is a circuit diagram showing an example of the safety circuit 13 of FIG. The same members as those shown in FIG. 6 are designated by the same reference numerals and the description thereof will be omitted.

A series voltage dividing circuit consisting of a fifth resistor 131 and a sixth resistor 132 is connected to the DC power source 1,
A sixth capacitor 133 is connected in parallel with the sixth resistor 132.
Are connected.

A series voltage dividing circuit composed of a seventh resistor 134 and an eighth resistor 135 is connected between the voltage dividing output point of the series voltage dividing circuit and the negative electrode side of the DC power source 1. .
The base terminal of the NPN-type second transistor 136 is connected to the series voltage dividing output point, the collector terminal thereof is connected to the base terminal of the first transistor 3, and the emitter terminal thereof is the DC power supply. Is connected to the negative electrode side. That is, this second transistor 136
When is turned on, the base terminal and the emitter terminal of the first transistor 3 are short-circuited.

Further, the voltage dividing output point of the series voltage dividing circuit composed of the seventh resistor 134 and the eighth resistor 135 is N
The collector terminal of the PN-type third transistor 137 is connected, and the emitter terminal of this third transistor 137 is connected to the negative electrode side of the DC power supply 1.

The fifth resistor 131 and the sixth resistor 1
A series circuit including a ninth resistor 138, a tenth resistor 139, and an eleventh resistor 140 is provided between the voltage dividing output point of the serial voltage dividing circuit including 32 and the negative electrode side of the DC power source 1. The connection point between the tenth resistor 139 and the eleventh resistor 140 is connected to the base terminal of the third transistor 137.

Further, the connection point is connected to the collector terminal of an NPN-type fourth transistor 141, and the emitter terminal of the fourth transistor 141 is connected to the negative side of the DC power supply 1.

The fifth resistor 131 and the sixth resistor 1
Between the voltage dividing output point of the serial voltage dividing circuit composed of 32 and the negative electrode side of the DC power source 1, an anode terminal of an SCR (Sillicon Controlled Rectifier) 143 is connected via a twelfth resistor 142. . The cathode terminal of the SCR 143 is connected to the negative electrode side of the DC power supply via the thirteenth resistor 144 and also to the base terminal of the fourth transistor.

The gate terminal of the SCR 143 is the 14th gate terminal.
Is connected to the negative electrode side of the DC power supply 1 via the resistor 145 and is also connected to the anode terminal of the Zener diode 146.

A fourteenth resistor 1 is provided between the connection point between the other end of the first filament 10a of the second discharge lamp 10 and the second capacitor 11 and the negative electrode side of the DC power supply 1.
A series voltage dividing circuit including a resistor 47 and a sixteenth resistor 148 is connected, and a seventh capacitor 149 is connected in parallel with the sixteenth resistor 148. The serial voltage dividing output point is
It is connected to the cathode terminal of the Zener diode 146.

Among the connection points of the fourth resistor 14c and the fourth capacitor 14d, the connection point which is not connected to the negative side of the DC power supply 1 is the PNP type fifth transistor 150. It is connected to the base terminal. The collector terminal of the fifth transistor 150 is connected to the negative electrode side of the DC power supply 1, and the emitter terminal thereof is connected to the anode terminal of the SCR 143.
It is connected to a connection point between the ninth resistor 138 and the tenth resistor 139 via a diode 151 inserted in the reverse direction.

That is, when one of the first discharge lamp 9 and the second discharge lamp 10 reaches the end of its life, the 14th resistor 1
When the voltage division output of the series voltage dividing circuit including the 47 and the 16th resistor 148 rises and exceeds the voltage set by the Zener diode 146, the SCR 143 is turned on.
Then, the fourth transistor 141 is turned on, and the third transistor 141 is turned on.
Transistor 137 is turned off, and the second transistor 136 is turned on. As a result, the base terminal and the emitter terminal of the first transistor 3 are short-circuited, the oscillation by the first transistor 3 is stopped, and the resonance coil 2, the first transistor 3, the first capacitor 4, and the control circuit. The function of protecting the inverter circuit composed of 6 etc. works. At this time, since the holding current flows through the SCR 143, the ON operation is held and the above-mentioned protection function is also held.

Here, when at least one of the first discharge lamp 9 and the second discharge lamp 10 is removed, the direct current flowing through the second resistor 14a is applied to the fifth capacitor 14e and the preheater. Via the coil 8, the third resistor 14b and the fourth resistor 14b
Is supplied to a parallel circuit composed of the resistor 14c and the fourth capacitor 14d, and the fifth capacitor 14e
Is charged, the charge level across the fourth capacitor 14d drops, the fifth transistor 150 is turned on, the anode terminal of the SCR 143 drops to ground, and the holding current is stopped. The protection function of the circuit 14 is released, and the third
The transistor 137 is turned off, the second transistor 136 is turned on, and the oscillation by the first transistor 3 is stopped.

Next, when the discharge lamp is mounted, the second resistor 1
The direct current flowing through 4a passes through the second filament 9b of the first discharge lamp 9 and the second filament 10b of the second discharge lamp 10 to the third resistor 14b and the fourth resistor 1b.
4c and the fourth capacitor 14d are supplied to the parallel circuit, and the fifth transistor 150 is turned off.
The third transistor 137 is turned on and the second transistor 136 is turned off so that the first transistor 3 can perform inverter oscillation.

[0035]

As described above, in the conventional discharge lamp lighting device for lighting two discharge lamps in series, the filaments 9b and 10b connected between the discharge lamps 9 and 10 are connected to each other. A ballast choke 7 and a preheating coil 8 are provided for preheating, and the preheating coil 8 is provided.
Is supplied to the filaments 9b and 10b which are connected to each other between the discharge lamps 9 and 10.
When the discharge lamp mounting circuit 14 is provided in this, a fifth capacitor 14e for cutting direct current must be provided.

However, the fifth capacitor 14e is required to have a high withstand voltage because the voltage necessary for lighting the discharge lamps 9 and 10 is applied, and moreover, the fifth capacitor 14e is used for preheating the filaments 9b and 10b. It is necessary to increase the capacity so that the impedance is low with respect to the alternating current. That is, as the fifth capacitor 14e, a capacitor having high withstand voltage and large capacity must be used, which causes a problem that the device becomes expensive and hinders downsizing.

When the discharge lamp is removed, the second resistor 14a, the third resistor 14b, the fourth resistor 14c and the fifth resistor 14c are removed.
There has been a problem that the removal of the discharge lamp cannot be detected unless the time due to the time constant of the condenser 14e has passed. Moreover, since the second resistor 14a and the third resistor 14b have high resistance values and the fifth capacitor 14e has a large capacitance, there is a problem in that the time constant takes a long time.

Therefore, the present invention does not use a high-voltage and large-capacity capacitor for cutting a direct current in a discharge lamp mounting detection circuit, and can detect that the discharge lamp has been removed in a short time. An object is to provide a lighting device.

[0039]

The invention according to claim 1 is
In a discharge lamp lighting device for controlling lighting of two discharge lamps connected in series, a direct current power supply and an inverter circuit for converting a direct current supplied from the direct current power supply into a high frequency current by causing a resonance coil to resonate with a chopper circuit. And a current limiting coil inserted in a current supply line for supplying a high frequency current from this inverter circuit to a series circuit composed of two discharge lamps, and a high frequency current from the inverter circuit flowing through the current limiting coil. An electric induction coil that converts the generated magnetic energy into electric energy, and a rectifier circuit that rectifies the current output from the electric induction coil,
A rectification current supply line for supplying a direct current rectified by a rectification circuit by connecting filaments on the mutually connected sides of each discharge lamp in series and a minute current from a direct current power supply through the rectification current supply line, A discharge lamp detecting means for detecting whether the discharge lamp is mounted or not mounted is provided according to the energization state of a minute current, and the direct current rectified from the rectifier circuit to the filaments on the mutually connected side of each discharge lamp through the rectification current supply line. An electric current is supplied for preheating.

The invention corresponding to claim 2 is the above-mentioned claim 1.
In the corresponding invention, a lighting starting capacitor for lighting two discharge lamps connected in series in series is connected in parallel to the discharge lamp connected to the positive electrode side of the DC power supply.

The invention according to claim 3 is a discharge lamp lighting device for controlling lighting of two discharge lamps connected in series,
DC power supply and DC current supplied from this DC power supply,
The chopper circuit resonates the primary coil of the transformer to convert it into high frequency current, and the inverter circuit that outputs the high frequency current from the secondary coil of the transformer to the discharge lamp, and the primary coil or secondary coil of the transformer. A magnetic energy generation coil that generates magnetic energy by the generated high-frequency current, an electric induction coil that converts the magnetic energy generated by this magnetic energy generation coil into electric energy, and a rectifier that rectifies the current output from this electric induction coil. The circuit and the rectifying current supply line that supplies the DC current rectified by the rectifier circuit by connecting the filaments on the mutually connected sides of the discharge lamps in series, and the minute current from the DC power supply through the rectification current supply line. Discharge lamp detection that detects whether the discharge lamp is mounted or not according to the flowing state of this minute current. A stage provided is for preheating is supplied from the rectifier circuit via a rectified current supply line direct current rectified in mutually connected side of filaments of the discharge lamps.

[0042]

In the invention according to claim 1, the magnetic energy generated by the current limiting coil inserted in the current supply line to the discharge lamp connected in series from the inverter circuit is converted into electric energy by the electric induction coil. The current that is converted and output from this electric induction coil is rectified by a rectifier circuit, and this rectified direct current is supplied to the filaments on the mutually connected sides of each discharge lamp by the rectified current supply line, and preheating is performed. Done.

A minute current is made to flow from the DC power source through the rectified current supply line, and the discharge lamp detecting means detects whether or not the discharge lamp is mounted by the energized state of this minute current.

According to the second aspect of the invention, the magnetic energy generated by the current limiting coil inserted in the current supply line to the discharge lamp connected in series from the inverter circuit is converted into electrical energy by the electric induction coil. The current that is converted and output from this electric induction coil is rectified by a rectifier circuit, and this rectified direct current is supplied to the filaments on the mutually connected sides of each discharge lamp by the rectified current supply line, and preheating is performed. Done.

A minute current is made to flow from the DC power source through the rectified current supply line, and the discharge lamp detecting means detects whether or not the discharge lamp is mounted by the energized state of this minute current.

At this time, a lighting starting capacitor for lighting the two discharge lamps in series is connected in parallel to the discharge lamp connected to the positive side of the DC power supply, so that the current from the DC power supply is used for lighting start. Never go around the capacitor.

In the invention corresponding to claim 3, the magnetic energy generated from the magnetic energy generating coil by the high frequency current generated by the primary side coil or the secondary side coil of the transformer of the inverter circuit is converted into electric energy by the electric induction coil. The current that is converted and output from this electric induction coil is rectified by a rectifier circuit, and this rectified direct current is supplied to the filaments on the mutually connected sides of each discharge lamp by the rectified current supply line, and preheating is performed. Done.

A minute current is made to flow from the DC power source through the rectified current supply line, and the discharge lamp detecting means detects whether or not the discharge lamp is mounted by the energized state of this minute current.

[0049]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIG.

FIG. 1 is a circuit diagram of essential parts showing a discharge lamp lighting device of a first embodiment to which the present invention is applied.

The DC power supply 21 for obtaining a DC current by rectifying and smoothing the AC current supplied from the commercial AC power supply,
A series circuit including a resonance coil 22 and an NPN transistor 23 is connected. That is, one end of the resonance coil 22 is connected to the positive electrode side of the DC power supply 21, and the other end of the resonance coil 22 is connected to the collector terminal of the transistor 23. The emitter terminal of the transistor 23 is connected to the negative side (ground) of the DC power supply 21.

A first resonance capacitor 24 is connected in parallel to the resonance coil 22, and the transistor 2 is connected to the resonance coil 22.
The base terminal of 3 is connected to the positive electrode side of the DC power source 21 via a first resistor 25, and is also connected to a control circuit 26 for ON / OFF controlling the transistor 23. The transistor 23 and the control circuit 26 form a chopper circuit, and the inverter circuit includes the chopper circuit, the resonance coil 22, and the first capacitor 24.

The connection point between the resonance coil 22 and the collector terminal of the transistor 23 is connected to one end of a ballast choke 27 as a current limiting coil.
The ballast choke 27 is provided with a preheating coil 28 as an electric induction coil that converts magnetic energy generated by a high frequency current flowing through the ballast choke 27 into electric energy.

A series circuit composed of a first discharge lamp 29 and a second discharge lamp 30 is connected between the positive electrode side of the DC power source 21 and the other end of the ballast choke 27.

That is, on the positive electrode side of the DC power source 21, the first filament 29a of the first discharge lamp 29 is provided.
Of the first filament 30a of the second discharge lamp 30 is connected to the other end of the ballast choke 27.
Is connected to one end of. The first of the first discharge lamps 29
A second capacitor 31 for preheating start is connected between the other end of the filament 29a of the second discharge lamp 30 and the other end of the first filament 30a of the second discharge lamp 30.

A positive terminal of a diode bridge circuit 32 as a rectifying circuit is connected to one end of the second filament 29b of the first discharge lamp 29, and the second filament 30b of the second discharge lamp 30 is connected. A negative terminal of the diode bridge circuit 32 is connected to one end of the diode bridge circuit 32, and both ends of the preheating coil 28 are connected to two AC input terminals of the diode bridge circuit 32. Also,
The other end of the second filament 29b of the first discharge lamp 29 and the second filament 30b of the second discharge lamp 30.
Is connected to the other end of. The positive terminal and the negative terminal of the diode bridge circuit 32, one end of the second filament 29b of the first discharge lamp 29 and the second filament 30b of the second discharge lamp 30, respectively.
A rectification current supply line is configured by a power supply line connecting one end of the second filament 30b and a connection line connecting the other ends of the second filaments 30b.

Between the positive electrode side of the DC power source 21 and the positive electrode side terminal of the diode bridge circuit 32, that is, in parallel with the first discharge lamp 29, a third capacitor as a lighting starting capacitor for series lighting starting. The capacitor 33 is connected.

Between the positive electrode side of the DC power source 21 and one end of the second filament 29b of the first discharge lamp 29, a second
Resistor 34 is connected, and a series circuit including a third resistor 35 and a fourth resistor 36 is provided between one end of the second filament 30b of the second discharge lamp 30 and the negative electrode side of the DC power supply 21. Are connected. A fourth capacitor 37 is connected in parallel with the fourth resistor 36.

The second resistor 34, the third resistor 35, the fourth resistor 36, and the fourth capacitor 37 constitute a discharge lamp mounting detection circuit as a discharge lamp detecting means. .

In the first embodiment having such a structure,
The transistor 23 is controlled to be turned on / off by the control circuit 26, and a high frequency current is generated by the action of the first capacitor 24 and the resonance coil 22. The generated high frequency current is limited to an optimum current amount by the ballast choke 27, and is supplied to the series circuit including the first discharge lamp 29 and the second discharge lamp 30.

At this time, the magnetic energy generated in the ballast choke 27 is converted into electric energy, that is, current by the preheating coil 28, and is further rectified by the diode bridge 32, so that the first discharge lamp 29 and the second discharge lamp 29 are discharged. Each second filament 29b and 30 of the electric lamp 30
It is supplied to b and preheated.

First, the voltage necessary for lighting the second discharge lamp 30 is applied to the second discharge lamp 30 by the third capacitor 33, the second discharge lamp 30 is lit, and the second discharge lamp 30 is lit and at the same time, The voltage required for lighting is applied to the first discharge lamp 29,
The first discharge lamp 29 is turned on.

For example, when at least one of the first discharge lamp 29 and the second discharge lamp 30 is removed, the second filament 29b of the first discharge lamp 29 or the second discharge lamp 30 is removed. At least one of 30b disappears, while the diode bridge 32 blocks the flow of current from the second resistor 34 to the third resistor 35, so that the second resistor 34 and the third resistor 35 are separated from each other. The space is completely disconnected.

Therefore, the voltage generated across the parallel circuit composed of the fourth resistor 36 and the fourth capacitor 37 instantaneously drops to the ground level, and the discharge lamp is removed for an extremely short time. Can be detected with.

When the third capacitor 33 is connected in parallel to the second discharge lamp 30, or when the second filaments 29b, 30 of the first discharge lamp 29 and the second discharge lamp 30 are connected.
The connection point directly connecting between b and each first filament 2
When connected to the other end of either 9a or 30a, the current flowing through the second resistor 34 may flow through the third capacitor 33, and in that case, the fourth resistor 36. The voltage generated across the parallel circuit composed of the fourth capacitor 37 and the fourth capacitor 37 may drop to some extent.

However, in the first embodiment, as shown in FIG. 1, since the third capacitor 33 is connected in parallel to the discharge lamp 29 connected to the positive electrode side of the DC power source 21, the second capacitor 33 is connected in parallel. There is no possibility that the current flowing through the resistor 34 will flow through the third capacitor 33, and therefore the voltage generated across the parallel circuit composed of the fourth resistor 36 and the fourth capacitor 37 does not normally drop.

As described above, according to the first embodiment, the preheating coil 28 for generating the electric power for preheating the mutually connected filaments 29b and 30b of the two discharge lamps 29 and 30 connected in series is provided. , The diode bridge circuit 3 for rectifying the alternating current output from the preheating coil 28
2 is provided and the third capacitor 33 for starting lighting for series lighting is connected in parallel to the first discharge lamp 29 connected to the positive electrode side of the DC power supply 21, so that the discharge lamp can be mounted / not mounted. In the discharge lamp mounting detection circuit for detecting, it is possible to detect that the discharge lamp is instantaneously removed without using a capacitor for cutting DC current.

Furthermore, since the third capacitor 33 is connected in parallel to the first discharge lamp 29 connected to the positive electrode side of the DC power source 21, the current flowing through the second resistor 34 is changed to the third capacitor 33. Since it can be prevented from flowing to 33, 2
When the book discharge lamp is mounted, the detection voltage generated at both ends of the parallel circuit including the fourth resistor 36 and the fourth capacitor 37 does not drop.

A second embodiment of the present invention will be described with reference to FIG.

FIG. 2 is a circuit diagram of essential parts of a discharge lamp lighting device showing a second embodiment to which the present invention is applied.

The difference between the second embodiment and the first embodiment described above is that the diode bridge is used in the first embodiment as the rectifier circuit, but in the second embodiment, the diode 38 is simply used. It was used. Therefore, FIG.
In FIG. 1, the same members as those in FIG.

As described above, also in the second embodiment, the same effect as in the first embodiment can be obtained.

The diode bridge 3 of the first embodiment
In the circuit using 2, the alternating current generated from the preheating coil 28 is full-wave rectified, whereas in the second embodiment, the diode 38 half-wave rectifies the alternating current from the preheating coil 28. Therefore, the preheating coil 28 is efficiently inferior to the diode bridge of the first embodiment.
If the output from the diode is sufficiently large, or if the number of turns of the preheating coil 28 is sufficiently large, the diode 38
It is possible to obtain the full effect alone.

A third embodiment of the present invention will be described with reference to FIG.

FIG. 3 is a circuit diagram of essential parts showing a discharge lamp lighting device according to a third embodiment of the present invention.

The difference between the third embodiment and the above-described first embodiment is that in the first embodiment, the resonance coil 22 is used, and the DC power supply 21, the first discharge lamp 29, and the second discharge lamp 29 are used. Although the discharge lamp 30 is connected without being insulated, in the third embodiment, the transformer 41 is used to connect the DC power source 21 and the first discharge lamp 29 and the second discharge lamp 30 while insulating them. It was done. Therefore, in FIG. 3, the same members as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted.

Between the positive electrode side of the DC power source 21 and the collector terminal of the transistor 23, one of the transformer 41 is provided.
The secondary coil 41a is connected, one end of the secondary coil 41b of the transformer 41 is connected to one end of the first filament 29a of the first discharge lamp 29, and the other end of the secondary coil 41b is It is connected to one end of the first filament 30 a of the second discharge lamp 30 via the ballast choke 27.

The ballast choke 27 is provided with a preheating coil 28, and both ends of the preheating coil 28 are
It is connected to the AC input terminal of the diode bridge circuit 32. The positive terminal of the diode bridge circuit 32 is connected to the second filament 29b of the first discharge lamp 29.
Is connected to one end of the second filament 30b of the second discharge lamp 30.

The other end of the second filament 29b of the first discharge lamp 29 and the other end of the second filament 30b of the second discharge lamp 30 are directly connected.

The third capacitor 33 as the lighting starting capacitor for starting the series lighting is the same as the second capacitor of the transformer 41.
One end of the secondary coil 41b and the first of the first discharge lamp 29
Is connected between the connection point with one end of the filament 29a and the positive terminal of the diode bridge 23.

A second resistor 3 is provided between the positive side of the DC power source 21 and the positive side terminal of the diode bridge 23.
4 is connected, and a series circuit composed of a third resistor 35 and a fourth resistor 36 is connected between the negative electrode side terminal of the diode bridge 23 and the negative electrode side of the DC power supply 21.
A fourth capacitor 37 is connected in parallel with the fourth resistor 36.

In this embodiment having such a configuration, the transistor 23 is controlled to be turned on / off by the control circuit 26, and a high frequency current is generated by the action of the first capacitor 24 and the primary coil 41a of the transformer 41. Due to the magnetic energy generated from the primary side coil 41a by this high frequency current, a high frequency current is generated in the secondary side coil 41b, and the generated high frequency current is limited to an optimum current amount by the ballast choke 27. Discharge lamp 2
9 and the second discharge lamp 30.

At this time, the magnetic energy generated in the ballast choke 7 is converted into electric energy, that is, current by the preheating coil 28, and is further rectified by the diode bridge 32 to generate the first discharge lamp 29 and the second discharge lamp 29.
Second filaments 29b and 30b of the discharge lamp 30 of
And is preheated.

First, the voltage necessary for lighting is applied to the second discharge lamp 30 by the third capacitor 33, the second discharge lamp 30 is lit, and the second discharge lamp 30 is lit and the second discharge lamp 30 is lit. The voltage required for lighting is applied to the first discharge lamp 29,
The first discharge lamp 29 is turned on.

For example, when at least one of the first discharge lamp 29 and the second discharge lamp 30 is removed, the second filament 29b of the first discharge lamp 29 or the second discharge lamp 30, At least one of 30b disappears, while the diode bridge 32 blocks the flow of current from the second resistor 34 to the third resistor 35, so that the second resistor 34 and the third resistor 35 are separated from each other. The space is completely disconnected.

Therefore, the voltage generated at both ends of the parallel circuit composed of the fourth resistor 36 and the fourth capacitor 37 instantaneously drops to the ground level, and the discharge lamp is removed for an extremely short time. Can be detected with.

As described above, according to the third embodiment, the preheating coil 28 for generating electric power for preheating the mutually connected filaments of the two discharge lamps 29 and 30 connected in series, and the preheating coil 28. Since the diode bridge circuit 32 for rectifying the alternating current output from the working coil 28 is provided, the direct current cut capacitor can be used in the discharge lamp mounting detection circuit for detecting the mounting / non-mounting of the discharge lamp. Without this, it is possible to detect that the discharge lamp is removed instantaneously.

In the third embodiment, the ballast choke 27 for current limiting is used as the magnetic energy generating coil.
In the above description, the one in which the preheating coil 28 as the electric induction coil is provided is described, but the present invention is not limited to this, and the primary side coil 41a of the transformer 41 is used as the magnetic energy generating coil. Side coil 41
A preheating coil 28 may be provided in a.

In the third embodiment, the second resistor 34, the third resistor 35, the fourth resistor 36 of the discharge lamp mounting detection circuit,
The DC power source 21 and the discharge lamp 2 are controlled by the fourth capacitor 37.
9 and 30 are not completely insulated, but the second resistor 3
Since the respective resistance values of the fourth and third resistors 35 are high and the flowing current is minute, an effect equivalent to that of insulation is obtained, that is, electric current that causes electric shock or ground drop flows in the work of mounting / removing the discharge lamp, for example. It is possible to obtain an effect such as no.

[0090]

As described above in detail, according to the present invention,
It is possible to provide a discharge lamp lighting device capable of detecting removal of a discharge lamp in a short time without using a high withstand voltage and large capacity capacitor for cutting a direct current in a discharge lamp mounting detection circuit.

[Brief description of drawings]

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

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

FIG. 4 is a circuit diagram showing a main part of a conventional discharge lamp lighting device.

FIG. 5 is a diagram showing another connection method (parallel connection) when two discharge lamps are serially connected.

FIG. 6 is a circuit diagram showing a main part of a conventional discharge lamp lighting device including a safety circuit and a discharge lamp mounting detection circuit.

FIG. 7 is a detailed circuit diagram showing an example of a safety circuit of a conventional discharge lamp lighting device.

[Explanation of symbols]

27 ... Ballast choke, 28 ... Preheating coil, 29,
30 ... Discharge lamp, 32 ... Rectifier circuit, 34, 35, 36 ... Resistor, 33, 37 ... Capacitor, 38 ... Diode, 41
... Transformer, 41a ... Primary coil.

Claims (3)

[Claims] 1. In a discharge lamp lighting device for controlling lighting of two discharge lamps connected in series, a DC power source and a high-frequency current by causing a resonance coil to resonate a DC current supplied from the DC power source by a chopper circuit. An inverter circuit for converting into a current limiting coil, a current limiting coil inserted in a current supply line for supplying a high frequency current from the inverter circuit to a series circuit including the two discharge lamps, and a high frequency current from the inverter circuit flows. By this, an electric induction coil that converts the magnetic energy generated by the current limiting coil into electric energy, a rectifying circuit that rectifies the current output from the electric induction coil, and the side of the discharge lamps connected to each other. A rectification current supply line for connecting a filament in series to supply a DC current rectified by the rectification circuit, and the DC power supply. A discharge lamp detecting means for detecting a mounted / dismounted state of the discharge lamp according to the energization state of the minute current, and a rectified current is supplied from the rectifier circuit to the rectified current supply line. A discharge lamp lighting device, characterized in that a rectified direct current is supplied to the filaments on the mutually connected side of each of the discharge lamps to preheat them. 2. A lighting starting capacitor for lighting two discharge lamps connected in series in series is connected in parallel to the discharge lamp connected to the positive electrode side of the DC power supply. The discharge lamp lighting device according to claim 1. 3. A discharge lamp lighting device for controlling lighting of two discharge lamps connected in series, wherein a DC power supply and a DC current supplied from this DC power supply are supplied to a primary coil of a transformer by a chopper circuit. An inverter circuit that resonates and converts into a high frequency current, and outputs a high frequency current from the secondary coil of the transformer to the discharge lamp;
A magnetic energy generation coil that generates magnetic energy by a high frequency current generated by a secondary coil or a secondary coil, an electric induction coil that converts the magnetic energy generated by the magnetic energy generation coil into electric energy, and the electric induction coil A rectifying circuit for rectifying the current output from the rectifying circuit, a rectifying current supply line for supplying a DC current rectified by the rectifying circuit by connecting in series filaments on the mutually connected sides of the discharge lamps, and the DC Discharge lamp detection means for detecting a mounting / non-mounting state of the discharge lamp by supplying a minute current from a power source through the rectified current supply line, and detecting whether the discharge lamp is mounted or not mounted is provided from the rectifier circuit to the rectified current supply line. Rectified direct current is supplied to the filaments on the mutually connected side of each discharge lamp through The discharge lamp lighting apparatus, characterized by heat.