JPH09237685A - Lighting system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lighting system in which arc discharge is not continued even when the arc discharge is generated by a contact failure or the like. SOLUTION: A constant current high frequency power source 1 uses an AC power source AC as a power source to output high frequency waves. A load circuit 2 supplies power through a current transformer Tr connected to an output line W to a lamp La. When arc discharge is generated by a contact failure or the like on the output line W, a phase detection circuit detects arc discharge generated based on phase difference between a voltage phase and a current phase, and it stops an output of the constant current high frequency power source 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lighting device for lighting a lighting load by the output of a constant current high frequency source.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 14, electric power is supplied from a constant-current high-frequency power source 1 using an AC power source AC such as a commercial power source to a load circuit 2 including a discharge lamp La as a lighting load. Therefore, a lighting device has been proposed in which the discharge lamp La is turned on (Japanese Patent Laid-Open No. 6-2039).
No. 82).

The load circuit 2 is an output wire W which is an insulation coated electric wire connected between the output terminals X and Y of the constant current high frequency power supply 1.
And a current transformer T in which a secondary winding n ₂ is wound around an annular core
r and a discharge lamp La connected between both ends of the secondary winding n ₂ of the current transformer Tr, a discharge lamp La having a filament is used, and a preheating capacitor C _{p is connected} to the discharge lamp La. It is connected between the non-power supply side ends of the filament. The output line W functions as a primary winding of the current transformer Tr by being inserted into the annular core of the current transformer Tr. In this configuration, even if there are a plurality of discharge lamps La, as many current transformers Tr as the number of discharge lamps La are provided, and the discharge lamps La are connected to the secondary winding n ₂ of each current transformer Tr and output. Since it is sufficient to insert the wire W into the current transformer Tr, there is an advantage that construction is easy regardless of the number of discharge lamps La.

[0004]

By the way, in the above-described lighting device, when the connection of the output line W to the output terminals X and Y is incomplete (contact failure between the output terminals X and Y and the output line W, Or if terminals with terminal screws are used as the output terminals X and Y, if the terminal screws are loose, etc.)
As described above, the current path between the output terminals X and Y of the constant-current high-frequency power source 1 (strictly speaking, in addition to the output line W, the connection portion between the output terminals X and Y and the output line W is also included, Arc discharge may occur at any one of (W). When the arc discharge occurs, the insulating coating of the output wire W is overheated and melts or burns to ignite or smoke, and in some cases, a problem may occur in that the core wire that is the charging portion is exposed.

In particular, with the high-frequency current output from the constant-current high-frequency power source 1, the voltage is applied again before the ionized ions are extinguished, so that arc discharge is more likely to continue as compared with the current at the frequency of the commercial power source, and the constant voltage is constant. Current high frequency power supply 1
Tries to keep the output current constant, the increase in the impedance on the output line W causes the voltage between the output terminals X and Y to rise, and the arc discharge is easily sustained.
As described above, in the lighting device that uses the constant-current high-frequency power supply 1 to turn on the lighting load, the arc discharge is likely to be sustained when the arc discharge occurs on the output line W.

As a configuration for lighting a lighting load using the constant current high frequency power source 1, as shown in FIG. 15, a configuration in which a current transformer Tr having a plurality of turns of primary winding n ₁ is provided is also considered. . In this lighting device, the current transformer T
r is connected to the output line W via the terminal block 6. Therefore, there are many electrical connections on the output line W,
Since there are more places where contact failure occurs, arc discharge is more likely to occur on the output line W.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a lighting device in which arc discharge does not continue even if arc discharge occurs due to contact failure or the like. .

[0008]

According to a first aspect of the present invention, a constant current high frequency power source for outputting a high frequency with a constant current from an AC power source as a power source, and a lighting load connected between output terminals of the constant current high frequency power source. A discharge circuit that detects the occurrence of arc discharge in the current path from the constant current high frequency power supply to the load circuit, and the output from the constant current high frequency power supply to the load circuit when arc discharge is detected by the discharge detection means. And a protection means for limiting the above.

According to this structure, when an arc discharge occurs due to a connection failure or the like in the load circuit connected between the output terminals of the constant current high frequency power supply, the arc discharge is detected and the output to the load circuit is output. Because of the limitation, it is possible to prevent the continuation of the arc discharge, and consequently prevent the arc discharge from falling into a dangerous state such as ignition or smoke.

According to a second aspect of the present invention, in the first aspect of the invention, the discharge detecting means comprises a phase detecting circuit for detecting a phase difference between the output voltage of the constant current high frequency power source and the current flowing through the load circuit. Is for determining that arc discharge has occurred when the current flowing in the load circuit leads the output voltage of the constant current high frequency power supply. According to a third aspect of the present invention, in the first aspect of the present invention, the discharge detecting means includes a current balance detection circuit that detects the symmetry of the waveform of the current flowing through the load circuit, and the magnitude of the current flowing through the load circuit varies depending on the direction. When it occurs, it is determined that arc discharge has occurred.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the discharge detecting means comprises a voltage balance detecting circuit for detecting the symmetry of the voltage waveform between the output terminals of the constant current high frequency power source, and the voltage waveform is asymmetrical. Then, it is determined that arc discharge has occurred. According to a fifth aspect of the invention, in the first to third aspects of the invention, the protection means stops the output from the constant current high frequency power supply to the load circuit when the arc discharge is detected.

According to a sixth aspect of the present invention, in the first to third aspects of the invention, when arc discharge is detected, the protection means intermittently supplies an output from the constant current high frequency power source to the load circuit. is there. According to a seventh aspect of the present invention, in the first to third aspects of the invention, the protection means reduces the output voltage from the constant current high frequency power supply to the load circuit when arc discharge is detected.

According to an eighth aspect of the present invention, in the first to seventh aspects of the present invention, the constant current high frequency power source is connected between the inductive impedance element inserted between the load circuit and the output terminal and the capacitive element connected between the output terminals. It is provided with at least one of an impedance element. According to this configuration, since the constant current high frequency power supply is provided with the inductive impedance element and the capacitive impedance element, even if the inductive impedance and the capacitive impedance of the load circuit fluctuate to some extent, they are not affected. .

The present invention is based on the following findings.
Considering the equivalent circuit of the load circuit 2 having the conventional configuration shown in FIGS. 14 and 15, the inductive impedance L ₀ is connected in series to the parallel circuit of the capacitive impedance C ₀ and the resistance component R ₀ as shown in FIG. It will be what you did. The inductive impedance L ₀ is mainly the inductance component of the output line W, and the resistance component R ₀ is mainly the resistance component of the lamp La. Therefore, when the lamp La is turned on, the vibration frequency f ₁ of this equivalent circuit is given by the equation ₁ .

[0015]

[Equation 1]

This is a normal time, but when an arc discharge is occurring on the output line W, the stray capacitance C _{1 of the} output line W is because the place where the discharge is occurring has the impedance Z.
Cannot be ignored. That is, the equivalent circuit is as shown in FIG. In this equivalent circuit, since the stray capacitance C ₁ is connected in series to the capacitive impedance C ₀ , the total amount of the capacitive impedance of the equivalent circuit is smaller than that of the equivalent circuit shown in FIG. 16, resulting in arc discharge. When it is, the vibration frequency f ₂ of the equivalent circuit is higher than that when no arc discharge occurs (f ₁ <f ₂ ). In other words, in the equivalent circuit of FIG. 17, the stray capacitance C ₁ is inserted in series in the equivalent circuit of FIG. 16, so that the phase of the current flowing through the load circuit 2 advances with respect to the phase of the voltage across the load circuit 2. However, the operation is similar to the current advance mode.

Further, when an arc discharge occurs, the direction in which the discharge is likely to occur and the direction in which the discharge is unlikely to occur can be made depending on the substances at both ends of the location where the arc discharge is occurring and the discharge state. During this time, the voltage varies depending on the voltage across the load circuit 2, the magnitude of the current flowing through the load circuit 2, and the direction of the current flowing through the load circuit 2.

As described above, the occurrence of arc discharge on the output line W is caused by the difference between the voltage phase and the current phase of the load circuit 2, the voltage across the load circuit 2 and the current flowing through the load circuit 2. It can be detected based on the difference between the peak values of both positive and negative polarities. Therefore, in order to prevent the continuation of the arc discharge, the arc discharge on the output line W is detected by the above-described technique, and when the arc discharge occurs, the voltage or the current to the load circuit 2 tends to become unsustainable. To control.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment 1) As shown in FIG. 1, this embodiment includes a constant-current high-frequency power source 1 that obtains a high-frequency output of a constant current by inputting an AC power source AC, and a load circuit 2 includes a current transformer Tr
And a discharge lamp La and a preheating capacitor C _p . The figure shows a configuration in which a plurality of discharge lamps La are lit,
A current transformer Tr and a preheating capacitor C _p are connected to each discharge lamp La. In addition, each current transformer Tr
Primary windings n ₁ are connected in series with each other. This configuration is the same as the conventional configuration shown in FIG. 15, but in the present embodiment, a phase detection circuit 3 as a discharge detection means and a protection means is inserted between the constant current high frequency power supply 1 and the load circuit 2,
The phase difference between the voltage phase between the output terminals X and Y connecting the load circuit 2 and the phase of the current flowing through the load circuit 2 is detected, and the output of the constant current high frequency power supply 1 is detected based on the detected phase difference. It is configured to control. Here, an inductor L is provided between the phase detection circuit 3 and the output terminals X and Y.
Is inserted.

As shown in FIG. 2, the constant-current high-frequency power source 1 boosts the output of the full-wave rectifier DB and a full-wave rectifier DB which is a diode bridge for full-wave rectifying an AC power source AC such as a commercial power source. A step-up chopper circuit 11 that outputs a smoothed DC voltage while preventing a pause in the input current, and a full-bridge inverter circuit that converts the DC voltage output from the chopper circuit 11 into a high-frequency AC voltage. It consists of 12.

As is well known, the chopper circuit 11 connects a series circuit of an inductor L ₁ and a switching element (MOSFET) Q ₁ between the DC output terminals of the full-wave rectifier DB,
Further, which the series circuit of the diode D ₁ to the switching element Q ₁ and the smoothing capacitor C _B connected in parallel, the switching element Q ₁ is controlled so as to turn on and off at a high frequency by the chopper control unit 13. Further, the voltage across the smoothing capacitor C _B is divided by the resistors R ₁ and R ₂ , and the chopper control unit 13 maintains the voltage across the smoothing capacitor C _{B at} a substantially constant voltage based on the voltage across the resistor R _2. P oN period of the switching element Q ₁ so that
WM control.

[0022] In the chopper circuit 11, the energy is accumulated in inductor L ₁ during the ON period of the switching element Q _1, inductor L ₁ in the OFF period of the switching element Q ₁
By adding the voltage of the output voltage of the voltage and the full-wave rectifier DB generated across the inductor L ₁ is applied to the smoothing capacitor C _B through the diode D ₁ when the energy is emitted from both ends of the smoothing capacitor C _B The voltage is boosted above the output voltage of the full-wave rectifier DB. Further, a current flows through the inductor L ₁ during the ON period of the switching element Q _1, since the OFF period of the switching element Q ₁ charging current flows to the smoothing capacitor C _B, the AC power source AC regardless of the voltage of the AC power supply AC Current can be continuously supplied to the full-wave rectifier DB from, and the input current distortion is smaller than that in the case where the DC voltage is obtained by using only the full-wave rectifier DB and the smoothing capacitor C _B without using the chopper circuit 11. The power factor can be increased.

The chopper control unit 13 described above is a general-purpose switch.
It uses an integrated circuit for an itching power supply.
For example, FA5331 manufactured by Fuji Electric or MC3326 manufactured by Motorola
1 can be used. The inverter circuit 12 is
Output voltage of the top circuit 11, that is, smoothing capacitor C_Bof
It outputs high-frequency AC voltage using the voltage at both ends as a power source.
Bridge-connected four switching elements (MO
SFET) Q_Two~ Q_FiveIs provided. Switching element Q_Two
And switching element Q_ThreeAnd are connected in series and bridge times
Forming one arm of the path, switching element Q_FourAnd su
Switching element Q_FiveIs connected in series with the bridge circuit
Forming the other arm, each arm is a smooth
Indexer C_BAre connected in parallel. Switching element
Child Q_TwoAnd switching element Q _ThreeThe connection point with is the inductor
Is connected to the output terminal X via L, and the switching element Q
_FourIs connected to the switching element Q5 at the current transformer C.
T₁First winding n₁₁Is connected to the output terminal Y via.

Since the load circuit 2 is connected between the output terminals X and Y, the switching element Q ₂ and the switching element Q are connected.
_{When 5} and are turned on, a current in the direction from the output terminal X to the output terminal Y flows into the load circuit 2 and the switching element Q
_{When the} switching element ₃ and the switching element Q ₄ are turned on, a current flows from the output terminal Y to the output terminal X in the load circuit 2. That is, as shown in FIG. 3, the smoothing capacitor C _B
A switching circuit Q ₂ , Q ₅ or Q ₃ , Q ₄ connected in series with the load circuit 2 sandwiched between both ends of is provided with a period during which the load circuit 2 is connected between both ends of the smoothing capacitor C _B. by turning on and off the switching element Q ₂ to Q ₅ so that the switching element Q ₂ to which are connected in series, Q ₃ or Q _4, Q ₅ is not turned on at the same time without passing through the AC voltage to the load circuit 2 Is applied. Also, all the switching elements Q ₂ to Q ₅ in the transient period when the current flowing through the load circuit 2 is inverted is provided with a period to be off, risk of short-circuiting across the smoothing capacitor C _B in each arm of the bridge circuit In addition to avoiding the above, a sinusoidal current is passed through the load circuit 2.

The current transformer CT ₁ has three windings,
The second winding n ₁₂ has a center tap,
_The current induced in ₁₂ is full-wave rectified using the diodes D ₂ and D ₃ . The third winding n ₁₃ is used without being rectified. Since the primary winding n ₁₁ of the current transformer CT ₁ are connected in series between the inverter circuit 12 as described above and the load circuit 2, a second winding n ₁₂ and the third winding of the current transformer CT ₁ The current flowing through the load circuit 2 can be detected based on the output of n ₁₃ .

One end of a series circuit of a diode D ₄ and a resistor R ₃ is connected to the connection point between the switching element Q ₂ and the switching element Q ₃ in the inverter circuit 12, and the voltage half-wave rectified by the diode D ₄ is applied. I take it out. By the way, since the inverter circuit 12 is the output part of the constant current high frequency power source 1, the inverter circuit 1
The output of 2 must be kept at a constant current. Therefore,
Based on the full-wave rectified output of the current induced in the second winding n ₁₂ of the current transformer CT ₁ , the switching elements Q ₂ to
The on / off timing of Q ₅ is controlled. Inverter control unit 14 for controlling the switching element Q ₂ to Q ₅ is configured as shown in FIG 4. Here, terminal A in FIG.
-C, EG, J, K, and P are connected to the terminals with the same reference numerals in FIG. Since current induced in the second winding n ₁₂ of the inverter control unit 14 in the current transformer CT ₁ flows through the sensing resistor R ₄ through terminal K, the current flowing through the voltage across the sensing resistor R ₄ to the load circuit 2 The size of can be detected. Capacitor C ₄ to the detection resistor R ₄ is the voltage across the parallel connection of the detecting resistor R ₄ is smoothed. Therefore, by inputting the voltage across the detection resistor R ₄ to the integrated circuit IC ₁ for controlling a general-purpose switching regulator, the switching element Q ₂ to the switching element Q ₂ to maintain the voltage across the detection resistor R ₄ substantially constant. Controls the on / off timing of Q ₅ . The control method of the switching element Q ₂ to Q _5, employing a duty control for controlling the ON period, either the frequency control for changing the switching frequency. The switching frequency is 4 depending on the operating conditions such as preheating, starting, and steady lighting of the discharge lamp La.
It is selected in the range of 0 to 100 kHz.

The integrated circuit IC ₁ is, for example, NEC.
Manufactured by μPC494 can be used. This integrated circuit IC ₁ has resistors R _t1 and R _t2 and a capacitor C _t which are externally attached.
Generates a sawtooth wave whose frequency is determined by and
By binarizing the sawtooth wave with a predetermined threshold value, the two types of rectangular waves shown in FIG. 3 are output. Both rectangular waves are given to the switching elements Q _{2 to} Q ₅ via the integrated circuits IC ₂ and IC ₃ for drivers, respectively. Integrated circuit IC ₂ ,
As IC ₃ , IR2111 used for a driver for an IR half-bridge inverter can be used.

The phase detection circuit 3 includes an inverter controller 14
For controlling an integrated circuit IC₁Direct current against
A pnp type transistor inserted in the power supply path from the power source E
TA Q _TenIs provided. This transistor Q_TenOn / off
Transistor Q₁₁Thyristor SCR via₁Controlled by
It is controlled. That is, the thyristor SCR₁Is on
Sometimes transistor Q_TenConnected in a relationship that turns off
You. Therefore, the thyristor SCR₁Is on
Transistor Q_Ten, Q₁₁Are both turned off and the integrated circuit I
C₁The inverter circuit by stopping the oscillation operation
The operation of 12 also stops. On the other hand, thyristor SCR₁But
If it is a transistor Q_TenIs turned on,
The data circuit 12 performs the above operation.

As described above, whether the thyristor SCR ₁ is turned on or off determines whether the inverter circuit 12 supplies power to the load circuit 2 or stops the power supply. Since the purpose of the present invention is to control so that the arc discharge does not continue when the arc discharge occurs on the output line W, the thyristor SCR ₁ is turned on when the arc discharge is detected to turn on the inverter circuit 12. It is enough to stop the operation.

The phase detection circuit 3 detects whether or not an arc discharge has occurred on the output line W. In the phase detection circuit 3, the voltage applied to the load circuit 2 is applied to the terminal P, and the current waveform flowing in the load circuit 2 is input through the terminal J. That is, the voltage applied to the terminal P is a voltage obtained by half-wave rectifying the voltage at the connection point of the switching elements Q ₂ and Q ₃ , and a rectangular wave voltage waveform as shown in FIG. 5E is obtained. Moreover, current input from the terminal J is shed detection resistor R ₁₁ third winding an induced current in the n ₁₃ of the current transformer CT _1, the terminal voltage of the detection resistor R ₁₁ is the resistance R
It is applied to the negative input terminal of the comparator CP ₁ via ₁₂ . A diode D ₁₂ is inserted between the negative input terminal of the comparator CP ₁ and the negative electrode of the DC power supply E, and the comparator C
The potential of the negative input terminal of P ₁ is clamped to the negative potential of the DC power source E. Therefore, as shown in FIG. 5B, the input voltage waveform of the comparator CP ₁ has a positive potential during the period when the current flowing through the load circuit 2 has a positive polarity and is absolutely positive during the period when the current flowing through the load circuit 2 has a negative polarity. Value is diode D ₁₂
Becomes a negative potential corresponding to the forward voltage drop of. However, if the polarity of the third winding n ₁₃ of the current transformer CT ₁ is reversed, the input voltage of the comparator CP ₁ becomes a positive potential while the current flowing through the load circuit 2 has a negative polarity. Here, FIG.
(B) to (i) show signal waveforms of the respective portions shown by b to i in FIG.

The comparator positive input of CP ₁ is set to a negative electrode potential of the DC power source E, the output of the constant comparator CP ₁ by pull-up resistor R ₁₃ is connected to the output terminal of the comparator CP ₁ H It is set to level. The period input to the negative input terminal of the comparator CP ₁ is a positive potential, from the output of the comparator CP ₁ becomes L level, the output of the comparator CP ₁ FIG 5 (c)
become that way. The output of the comparator CP ₁ is the negative circuit N
_As shown in FIG. 5 (d), the current that is inverted by ₁ and flows through the load circuit 2 becomes a rectangular wave that becomes H level during the positive polarity period, and this rectangular wave is input to the clock terminal CK of the D flip-flop FF _1. .

On the other hand, the voltage applied to the terminal P is clamped to the negative potential of the DC power source E by the diode D ₁₃ .
It is input to the data terminal D of the D flip-flop FF ₁ through a delay circuit composed of two NOT circuits, a resistor R ₁₄ and a capacitor C ₁₄ . Therefore, even if the voltage applied to the terminal P includes noise, it is removed by the delay circuit, and the input voltage waveform shown in FIG. 5 (e) is delayed as shown in FIG. 5 (g). A rectangular wave is obtained.
FIG. 5F is a waveform showing the terminal voltage of the capacitor C ₁₄ in the delay circuit.

The D flip-flop FF ₁ outputs the level of the output of the NOT circuit N ₃ which is a data input from the non-inverting output terminal at the time of rising of the output of the NOT circuit N ₁ which becomes the clock signal. In the normal state, the current waveform is delayed with respect to the voltage waveform. Therefore, the non-inverted output of the D flip-flop FF ₁ is at the H level as shown in FIG. ). On the other hand, when an arc discharge occurs on the output line W, the current waveform has a phase advance with respect to the voltage waveform, as described in the explanation of the principle. That is, when the discharge arc occurs at time t _a of Figure 5, than the time t _a it data input to the L level at the rising edge of the clock signal to the D flip-flop FF ₁ as the right non-inverting output L Become a level.

D flip-flop FF₁Non-inverting output end of
Is the diode D_FifteenAnd resistance R_FifteenThrough the resistor R_t1, R
_t2D flip-flop FF
₁When the non-inverted output of is at L level, the resistor R_t1, R_t2of
The potential at the connection point is lowered to the negative potential of the DC power source E.
You. That is, the switching element Q_Two~ Q_Fiveof
Switching frequency is resistor R_t1, R_t2To the series combined resistance of
Discharge arc occurs, which was determined by
By resistance R_t1The switching frequency is determined only by
The switching frequency shifts to the high frequency side
Will be done. Also, the D flip-flop FF₁Anti
The output terminal is diode D₁₆And resistance R₁₆And capacitor C₁₆
Is connected to the negative electrode of the DC power supply E via₁₆And
Indexer C ₁₆The connection point with is Zener diode ZD₁To
Through thyristor SCR₁Connected to the gate.
In addition, Zener diode ZD₁Is a D flip-flop
FF ₁The inverted output of becomes H level, and the capacitor C₁₆of
When the voltage between both ends rises to a predetermined value, it conducts and the thyristor S
CR₁Is selected to be able to turn on
You. Conversely, D flip-flop FF₁Inverted output of
Resistance R₁₆And capacitor
C₁₆Within the time determined by
ZD₁Does not turn on.

However, first, in order to explain the normal operation, the current flowing into the terminal J is delayed rather than the voltage applied to the terminal P during the preheating of the discharge lamp La, and the starting state is entered. If this is done, the phase-advancing operation approaches the phase-advancing operation. When the phase advancing operation is approached, the non-inverted output of the D flip-flop FF ₁ becomes L level and the inverted output thereof becomes H level. Therefore, the switching frequency shifts to the high frequency side and is maintained at a frequency higher than the resonance frequency of the load circuit 2, and the switching element Q ₂
~ Q ₅ is protected from excessive stress. On the other hand, the inverted output of the D flip-flop FF ₁ goes to the H level, but when operating normally, the starting state changes to the lighting state within the time set by the resistor R ₁₆ and the capacitor C ₁₆ , Zener diode ZD ₁
Does not become conductive, and in the lit state, the operation returns to the delay phase operation and the inverted output of the D flip-flop FF ₁ returns to the L level.

When the light is turned on, time t _a in FIG.
The switching frequency of the inverter circuit 12 is determined by the series combined resistance of the resistors R _t1 and R _{t2 because} the phase delay operation is performed as shown previously. When an arc discharge on the output line W occurs, it becomes a time t _a subsequent operation in FIG. 5, the current being input to the terminal J approaches the fast with respect to the voltage applied to the terminal P. Therefore, since the non-inverted output of the D flip-flop FF ₁ becomes L level,
First switching frequency is to prevent excessive stress from being applied to the switching element Q ₂ to Q ₅ by shifting the high frequency side. Furthermore, if this state continues, the voltage across the capacitor C ₁₆ rises, and the Zener diode ZD ₁ becomes conductive, and the thyristor SC
Turn on R ₁ . As a result, the transistor Q ₁₀ is turned on, the power supply to the integrated circuit IC ₁ is stopped, and all the switching elements Q _{2 to} Q ₅ are turned off. That is, the inverter circuit 12 stops operating and the power supply to the load circuit 2 is stopped. As described above, when the arc discharge occurs on the output line W, the continuation of the arc discharge is avoided, and it is possible to prevent smoking or ignition.

Since the inductance component and the stray capacitance between the output terminals X and Y greatly change depending on the length of the output line W (for example, when the output line W is 20 m, the vibration frequency becomes about 180 kHz, The experimental result has been obtained that the vibration frequency becomes about 120 kHz when W is 60 m), and the length of the output line W is changed by inserting an inductor L as an inductive impedance element in series with the output line W. The rate of change of the inductance component with respect to is reduced. By using the inductor L as described above, the change in the oscillation frequency with respect to the change in the length of the output line W is reduced, and the change in the detection level of the phase advance current with respect to the change in the length of the output line W can be reduced. As a result, the change in the detection level of the occurrence of arc discharge becomes small, and it becomes easy to deal with the change in the length of the output line W. Further, by connecting a capacitor as a capacitive impedance element between the output terminals X and Y, it is possible to suppress the influence of the change in the stray capacitance due to the change in the length of the output line W.

(Embodiment 2) This embodiment is another configuration example in which the phase control circuit 3 controls the inverter control unit 14, and the elements having the same reference numerals as those in the circuit shown in FIG. 6 are the same. It has a function. The main difference between the present embodiment and the first embodiment is that in the first embodiment, the inverter Q is controlled by controlling the transistor Q ₁₀ inserted in the power supply path of the integrated circuit IC ₁ when an arc discharge occurs on the output line W. While the operation of the circuit 12 is stopped, in the present embodiment, there is provided a period in which the signal from the integrated circuit IC ₁ to the driver integrated circuits IC ₂ and IC ₃ becomes invalid when an arc discharge occurs. As a result, the inverter circuit 12 is intermittently operated to reduce the power supplied to the load circuit 2.

That is, between the two output terminals of the integrated circuit IC ₁ and the negative electrode of the DC power source E, the collector and emitter of the npn type transistors Q ₁₂ and Q ₁₃ are inserted, respectively, and both transistors Q ₁₂ and Q ₁₃ are inserted. Is connected to the connection point of resistors R ₁₇ and R ₁₈ connected in series between the collector of the pnp type transistor Q ₁₄ and the negative electrode of the DC power source E. Further, the transistor Q ₁₄ is turned on and off is controlled by the transistor Q ₁₅ of the npn type, are connected to the ON state of the transistor Q ₁₅ as the transistor Q ₁₄ is also turned on. The base of the transistor Q ₁₅ is connected to the connection point between the resistor R ₁₆ and the capacitor C ₁₆ via the Zener diode ZD ₂ , and if the voltage across the capacitor C ₁₆ rises and the Zener diode ZD ₂ turns on, Transistors Q ₁₂ , Q
₁₃ is for stopping the operation of the switching element Q ₂ to Q ₅ is turned on. A series circuit of a resistor R ₁₉ and a capacitor C ₁₉ is also connected between the collector of the transistor Q ₁₄ and the negative electrode of the DC power source E, and the resistor R ₁₉ and the capacitor C ₁₉ are connected.
The base of the transistor Q ₁₆ is connected to the connection point with the zener diode ZD ₃ . The collector-emitter of the transistor Q ₁₆ is connected in parallel with the capacitor C ₁₆ .

In the normal state, the phase detection circuit 3 is integrated circuit I
Since it does not affect the operation of C _{1 to} IC ₃ , it operates similarly to the first embodiment. On the other hand, when arc discharge occurs on the output line W, the D flip-flop F
The non-inverted output of F ₁ becomes L level and the inverted output becomes H level. Therefore, first, the connection point of the resistors R _t1 and R _t2 becomes the negative potential of the DC power source E, and the switching frequency shifts to the high frequency side. After that, resistor R ₁₆ and capacitor C ₁₆
After a lapse of time determined by, the Zener diode ZD ₂ becomes conductive and, as a result, the transistors Q ₁₂ , Q ₁₃
Turns on. That is, the integrated circuit IC ₂ for the driver,
The signal from the integrated circuit IC ₁ is not input to the IC _3, and the switching elements Q _{2 to} Q _{5 of the} inverter circuit 12 are input.
Is not turned on and off, and the operation of the inverter circuit 12 stops.

By the way, since a series circuit of the collector of the transistor Q ₁₄ and the resistor R ₁₉ and capacitor C ₁₉ is connected, the resistance after ON of the transistor Q _12, Q ₁₃ R ₁₉
After a lapse of time determined by the capacitor C ₁₉ and the capacitor C ₁₉ , the Zener diode ZD ₃ becomes conductive and the transistor Q ₁₅ is turned on. That is, transistor Q ₁₄ turns off,
The inverter circuit 12 resumes operation. Transistor Q
_{When 14} is turned off, the capacitor C ₁₉ is discharged through the resistors R _{17 to} R ₁₉ , and the transistor Q ₁₅ is turned off again to stop the inverter circuit 12.

By repeating the above operation, the inverter circuit 12 operates intermittently and the output line W
The energy supplied to the is reduced, and as a result, the arc discharge cannot be sustained. Further, if the inverter circuit 12 operates intermittently, the lamp La blinks. Therefore, by setting the cycle of the intermittent operation so that the blinking of the lamp La can be perceived, the blinking of the lamp La notifies the user of an abnormality. It is possible. Other configurations and operations are the same as those of the first embodiment.

(Embodiment 3) In this embodiment, as shown in FIG. 7, the basic construction is the same as that of FIG. 2, but the chopper control unit 13 for controlling the chopper circuit 11 is constructed as shown in FIG. I am doing it. Further, although the phase detection circuit 3 controls the inverter control unit 14 in the first and second embodiments,
In this embodiment, the phase detection circuit 3 is configured to control the chopper control unit 13. Further, in the present embodiment, the line filter L is provided between the AC power source AC and the full-wave rectifier DB.
F is inserted. However, it is desirable to provide the line filter LF also in the first and second embodiments.

The chopper circuit 11 is provided with another pair of resistors R ₅ and R ₆ for dividing the output voltage in addition to the resistors R ₁ and R ₂ for dividing the output voltage similar to the circuit configuration shown in FIG. Resistors R ₇ and R _{8 for} dividing the input voltage to the chopper circuit 11 are also added. A detection resistor R _s is inserted between the negative output terminal of the full-wave rectifier DB and the source of the switching element Q ₁ . The voltage across the detection resistor R _s is proportional to the current flowing in the chopper circuit 11.

On the other hand, the chopper controller 13 is shown in FIG.
Is controlled by the phase detection circuit 3. Here, FIG.
And terminals J1 to J4 and terminals J and P in FIG.
Connected to each other. In the first embodiment, the chopper control unit 13 is
As described, the integrated circuit IC for the switching power supply_Four
Attach the external parts to the FA5331 manufactured by Fuji Electric here.
It is composed by adding. The phase detection circuit 3 is basically implemented.
It has the same configuration as that shown in the first embodiment. Sand
D flip-flop FF₁From terminals J and P
To control the chopper control unit 13. here
Then, D flip-flop FF₁The input side configuration of
Has the same configuration as that of the first embodiment. On the other hand, D
Flip-flop FF₁Output is only inverted output
, D flip-flop FF₁Resistor R at the inverting output of
₂₀And capacitor C₂₀And Zener diode ZD_FourAnd from
Through the delay circuit that becomes_{twenty one}The base of
Has been continued. This transistor Q_{twenty one}Is the transistor Q
_{twenty two}Through transistor Q_{twenty three}Control the on / off of
Transistor Q_{twenty three}Is an integrated circuit IC_FourInsert into the power supply path of
It is included. Here, the transistor Q_{twenty one}~ Q_{twenty three}Is a tiger
Transistor Q_{twenty one}Is turned on, transistor Q_{twenty three}Turned off
D flip-flop FF₁
After the inverted output of becomes H level, the resistance R₂₀And con
Densa C₂₀After the time set by
-Diode ZD_FourTurns on and transistor Q_{twenty one}On
Resulting in integrated circuit IC_FourTo stop the power supply to
Switching element Q of chopper circuit 11₁Stop controlling
It is made to let. Chopper circuit 11 is a full wave
Inductor L at the output end of sink DB₁And diode D
₁Smoothing capacitor C via_BIs connected,
Switching element Q ₁Smoothing capacitor C even when is off
_BVoltage is generated across both ends of the
, Smoothing capacitor C_BThe voltage across both ends is lower than normal
Will be done. That is, the output from the constant current high frequency power supply 1
The output voltage will decrease.

In the normal state, however, the phase of the current waveform flowing from the terminal J is delayed with respect to the voltage waveform applied to the terminal P, so the D flip-flop FF
The inverted output of ₁ is at the L level, and the chopper control unit 13
Performs normal operation. At this time, the chopper control unit 13
Not only detects the output voltage and keeps the output voltage constant (for example, the voltage across the smoothing capacitor C _B is 350 V).
The power factor is controlled to be kept high based on the input voltage, the output voltage, and the phase of the circuit current of the chopper circuit 11.

On the other hand, when a discharge arc is generated on the output line W, the inverted output of the D flip-flop FF ₁ becomes H level as in the first embodiment. Therefore, as described above, the resistance R ₂₀ and the capacitor C ₂₇ are used. The operation of the chopper control unit 13 stops after the lapse of the determined time. That is, the switching element Q ₁ is kept off, and the voltage across the smoothing capacitor C _B drops to the output voltage of the full-wave rectifier DB (for example,
If the voltage of the AC power supply AC is 200V, the voltage across the smoothing capacitor C _B is 282V). In this way, the output voltage decreases with the occurrence of the arc discharge on the output line W, and the energy of the arc discharge is suppressed, so that the continuation of the arc discharge is prevented. Other configurations and operations are the same as those of the first embodiment.

(Embodiment 4) In the present embodiment, the voltage across the load circuit 2 and the phase of the current flowing through the load circuit 2 are not detected from the constant-current high-frequency power source 1, but as shown in FIGS. 9 and 10. , Output terminal T of constant current high frequency power supply 1
The primary winding n ₂₁ of the current transformer CT ₂ is inserted between the load circuit 2 and the output terminal Y to which the load circuit 2 is connected, so that only the current flowing through the load circuit 2 is detected. The secondary winding n ₂₂ of the current transformer CT ₂ has a tap, and the tap is connected to the negative electrode of the DC power supply C (not shown). Therefore, a current corresponding to the direction of the current flowing through the primary winding n ₂₁ is induced at each end of the secondary winding n ₂₂ . In this embodiment, the current balance detection circuit 4 functioning as a discharge detection means and a protection means is used to detect an imbalance in the magnitude of the current (asymmetry of the current waveform) depending on the direction of the current flowing through the load circuit 2. The occurrence of arc discharge on the output line W is detected.

However, between the one end of the secondary winding n ₂₂ and the negative electrode of the DC power source E, a diode D ₂₁ and two resistors R ₂₁ ,
A series circuit with R ₂₂ is connected, and between the other end of the secondary winding n ₂₂ and the negative electrode of the DC power source E, a diode D ₂₂ and a resistor R ₂₃ ,
A series circuit with R ₂₄ is connected. Further, capacitors C ₂₂ and C ₂₄ are connected in parallel to the resistor R ₂₂ and the resistor R ₂₄ , respectively. The connection point of the resistors R _{21 to} R ₂₄ is the differential input detection circuit U
It is connected to both input terminals of S, respectively. Here, the tap of the current transformer CT ₂ is the center tap, and R ₂₁ : R
₂₂ = R ₂₃ : Assume that R ₂₄ is set.

The differential input detection circuit US is a circuit for supplying a current to the output when a potential difference occurs at both input terminals, and is a pnp.
A pair of transistors Q _27, Q ₂₈ in the form, together with the resistor R ₂₆ is inserted between the base of the transistors Q _27, Q _28, the base and emitter of the transistors Q _27, Q ₂₈ are connected to each other, Further, the collectors are commonly connected and serve as an output terminal. Further, the resistors R ₂₂ , R ₂₄ and the capacitors C ₂₂ , C ₂₄ are provided. Thus, both input terminals (i.e., resistor R _21, a connection point of the connection point between the resistor R _23, R ₂₄ of R ₂₂₎ the difference in potential between occurs, the transistor Q whose emitter towards high potential is connected ₂₇ and Q ₂₈ are turned on, and current is passed to the output.

The output terminal of the difference input detection circuit US is connected to the positive input terminal of the comparator CP ₂ via a time constant circuit composed of a resistor R ₂₅ and a capacitor C ₂₅ . Comparator CP
_{When the} reference voltage is applied to the negative input terminal of _{2 and} the signal input to the positive input terminal exceeds the reference voltage, the comparator CP ₂
Output becomes H level. The output terminal of the comparator CP _2, the output is connected to the thyristor SCR ₂ to turn on at the H level, the thyristor SCR ₂ is the base of the transistor Q ₂₅ - is connected between the emitter. This transistor Q ₂₅ is a transistor Q ₂₆ which is inserted in the power feeding path of the integrated circuit IC ₁ which constitutes the inverter control unit 14.
Is turned on and off, and the thyristor SCR ₂ and the transistors Q ₂₅ and Q ₂₆ are connected so that the transistor Q ₂₆ turns off when the thyristor SCR ₂ turns on.

Now, the current flowing through the load circuit 2, that is,
Current transformer CT_TwoPrimary winding n _{twenty one}To the current flowing in
Considering this, as shown in the left part of FIG.
, The peak values are almost equal regardless of the direction of the current. This
Then capacitor C_{twenty two}, C_{twenty four}The terminal voltages of are almost equal
Therefore, the differential input detection circuit US does not operate, and the capacitor
C_{twenty five}Terminal voltage is comparator CP_TwoThan the reference voltage of
Kept low. As a result, the comparator CP_Twoof
The output is kept at L level and the thyristor SCR_TwoIs on
However, the inverter control unit 14 operates normally.

On the other hand, if an arc discharge is generated on the output line W, there are a direction in which the discharge is easy and a direction in which the discharge is difficult depending on the substances at both ends of the arc discharge and the discharge state. Therefore, as shown in the right part of FIG. The peak value changes according to the direction of the current flowing through the load circuit 2. That is, in the load circuit 2, the impedances Z ₁ and Z ₂ are connected in series to the rectifying diodes D _a and D _b , respectively, as shown in FIG. 12, and the polarity of the diodes D _a and D _b is reversed in both series circuits. Is equivalent to a parallel connection. When the magnitude relationship of the magnitude of the current depending on the direction of the current is as shown in FIG. 11 (that is, Z ₁ <Z ₂ ), the resistance R ₂₃ and the resistance R ₂₂ are more than the potential at the connection point of the resistance R ₂₁ and the resistance R _22. The potential at the connection point with ₂₄ becomes higher. That is, the capacitor C ₂₅ is charged through the resistor R ₂₅ by the current output from the differential input detection circuit US,
When the terminal voltage of the capacitor C ₂₅ becomes higher than the reference voltage, the output of the comparator CP ₂ becomes H level. As a result, the transistor Q ₂₆ turns off as described above,
The operation of the inverter control unit 13 stops and the operation of the inverter circuit 12 also stops.

In this way, the arc discharge on the output line W
Detects the occurrence and stops the output of the inverter circuit 12
You can do it. Other configurations and operations are implemented
Same as in the first embodiment. (Fifth Embodiment) As shown in FIG.
The configuration is almost the same as that of the fourth embodiment, but in the fourth embodiment.
While the current flowing through the load circuit 2 was detected,
In this embodiment, as the discharge detection means and the protection means,
Of the load circuit 2 using the functioning voltage balance detection circuit 5.
Detects voltage unbalance (voltage waveform asymmetry)
The difference is. Therefore, the current transformer CT_TwoTo
Without providing each end of the differential input detection circuit US to the output terminals X, Y
Each is connected. The diode D_{twenty one}, D _{twenty two}You
And the capacitor C in the differential input detection circuit US_{twenty two}, C_{twenty four}
Is omitted. Other configurations are similar to those of the fourth embodiment.

However, when an arc discharge occurs on the output line W, the peak value of the current differs depending on the direction of the current, so the average value of the potential between the output terminals X and Y is 0V.
Not be. As a result, the capacitor C ₂₅ is charged via the resistor R _25, the terminal voltage of the capacitor C ₂₅ is equal to or higher than the reference voltage set in the comparator CP _2, the output of the comparator CP ₂ is the H level Therefore, the operation of the inverter control unit 14 is stopped.
The other configurations and operations are similar to those of the fourth embodiment, and therefore the description thereof is omitted.

In the above embodiment, the full bridge type inverter circuit 12 is used, but it is needless to say that the technical idea of the present invention can be applied to the inverter circuit 12 having another configuration. Nor.

[0057]

Industrial Applicability The present invention uses a constant current high frequency power source that outputs a high frequency with a constant current as an AC power source, a load circuit including a lighting load connected between the output terminals of the constant current high frequency power source, and a constant voltage. Discharge detecting means for detecting the occurrence of arc discharge in the current path from the current high frequency power supply to the load circuit, and protection means for limiting the output from the constant current high frequency power supply to the load circuit when arc discharge is detected by the discharge detecting means. It is provided, and when an arc discharge occurs due to a connection failure in the load circuit connected between the output terminals of the constant current high frequency power supply, the arc discharge is detected and the output to the load circuit is limited, There is an advantage that it is possible to prevent the continuation of the arc discharge, and consequently prevent the arc discharge from falling into a dangerous state such as ignition or smoke.

Further, in the case where the constant current high frequency power supply includes at least one of the inductive impedance element inserted between the load circuit and the capacitive impedance element connected between the output terminals, the inductive characteristic of the load circuit Even if the impedance or the capacitive impedance fluctuates to some extent, there is an advantage that it is not affected.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment.

FIG. 2 is a circuit diagram of a main part of the first embodiment.

FIG. 3 is an operation explanatory diagram of the inverter circuit used in the first embodiment.

FIG. 4 is a circuit diagram of a main part of the first embodiment.

5 is an operation explanatory diagram of the circuit shown in FIG. 4;

FIG. 6 is a circuit diagram of a main part of the second embodiment.

FIG. 7 is a main part circuit diagram of a third embodiment.

FIG. 8 is a main part circuit diagram of a third embodiment.

FIG. 9 is a main part circuit diagram of a fourth embodiment.

FIG. 10 is a main part circuit diagram of a fourth embodiment.

FIG. 11 is an operation explanatory diagram of the fourth embodiment.

FIG. 12 is an equivalent circuit diagram showing an operation state of the fourth embodiment.

FIG. 13 is a main-portion circuit diagram of the fifth embodiment.

FIG. 14 is a circuit diagram showing a conventional example.

FIG. 15 is a circuit diagram showing another conventional example.

FIG. 16 is an equivalent circuit diagram of a load circuit.

FIG. 17 is an equivalent circuit diagram of a load circuit when arc discharge is occurring.

[Explanation of symbols]

 1 constant current high frequency power supply 2 load circuit 3 phase detection circuit 4 current balance detection circuit 5 voltage balance detection circuit AC AC power supply L inductor La lamp Tr current transformer W output line

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasuhiro Kudo 1048, Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Works Ltd. (72) Yoshimitsu Hiratsune, 1048, Kadoma, Kadoma City, Osaka Matsushita Electric Co., Ltd.

Claims (8)

[Claims] 1. A constant current high frequency power source that outputs a high frequency with a constant current using an AC power source as a power source, and a load circuit including a lighting load connected between output terminals of the constant current high frequency power source,
Discharge detection means for detecting the occurrence of arc discharge in the current path from the constant current high frequency power supply to the load circuit, and protection means for limiting the output from the constant current high frequency power supply to the load circuit when arc discharge is detected by the discharge detection means. A lighting device comprising: 2. The discharge detecting means comprises a phase detection circuit for detecting the phase difference between the output voltage of the constant current high frequency power supply and the current flowing through the load circuit, and the phase detection circuit is such that the current flowing through the load circuit is the constant current high frequency power supply. The lighting device according to claim 1, wherein it is determined that arc discharge has occurred when the output voltage is advanced. 3. The discharge detecting means comprises a current balance detecting circuit for detecting the symmetry of the current waveform flowing in the load circuit,
The lighting device according to claim 1, wherein it is determined that an arc discharge is occurring when a difference in magnitude of a current flowing through the load circuit occurs depending on a direction. 4. The discharge detection means comprises a voltage balance detection circuit for detecting the symmetry of the voltage waveform between the output terminals of the constant current high frequency power supply, and when the voltage waveform becomes asymmetric, it is determined that arc discharge has occurred. The lighting device according to claim 1, which is characterized in that: 5. The lighting device according to claim 1, wherein the protection means stops the output from the constant current high frequency power supply to the load circuit when the arc discharge is detected. 6. The lighting device according to claim 1, wherein the protection means intermittently supplies an output to the load circuit from the constant-current high-frequency power source when an arc discharge is detected. 7. The lighting device according to claim 1, wherein the protection means reduces the output voltage from the constant current high frequency power supply to the load circuit when the arc discharge is detected. 8. The constant current high frequency power supply comprises at least one of an inductive impedance element inserted between the load circuit and a capacitive impedance element connected between the output terminals. The lighting device according to claim 7.