JPH07211467A - High-frequency power source device for parallel, multiple lighting - Google Patents

Abstract

PURPOSE:To turn on a number of neon tubes in parallel at a rated output of 1000 V or less. CONSTITUTION:A high-frequency inverter circuit 32 converts commercial AC power into high-frequency power and supplies it to an output transformer 18, and neon tubes 54 to 57 are connected in parallel to the secondary side of the output transformer 18 via respective current-limiting capacitors 51 to 53. As FETs 16, 17 are alternately turned on and off by a switching regulator IC 22, the high-frequency power is supplied to the transformer 18 so as to turn on the neon tubes. When no load is applied to the output transformer 18 and the current of the inverter circuit 32 decreases, the dropping voltages at both ends of a current-detecting resistor 35 are decreased and a transistor 39 is turned off. Therefore, the voltage of the terminal number 15 of the IC 22 becomes higher than that of the terminal number 16, and oscillation of the IC 22 is stopped by an output of a comparator provided inside the IC.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention connects discharge tubes such as neon tubes and argon tubes in parallel to the output side of a high frequency inverter circuit via current limiting elements such as capacitors and induction elements. TECHNICAL FIELD The present invention relates to a high-frequency power supply device for lighting multiple parallel lights that is turned on.

[0002]

2. Description of the Related Art When commercial AC power is boosted by using a neon transformer and applied to a discharge tube such as a neon tube or an argon tube to light a lamp, the effective value of the output voltage under load, that is, in a lighting state. In comparison with the above, the output voltage under no load is about 2 to 3 times, and the output voltage waveform under no load is almost sinusoidal, so the crest factor is about 1.4 to 1.5.

On the other hand, when the discharge tube is lit with high-frequency power, the load impedance of the discharge tube is small in a loaded state, so that the waveform is close to a sine wave output voltage due to the influence of stray capacitance. If the wire is disconnected or the gas in the discharge tube escapes and the load becomes unloaded, the load impedance becomes extremely large.Therefore, the inductance of the output transformer that boosts the high frequency voltage and the stray capacitance on the discharge tube side. Due to the resonance phenomenon, the output voltage rises and waveform distortion occurs, and a very large peak voltage appears, which is dangerous. This phenomenon is more remarkable as the output voltage is higher and the oscillation frequency is higher. Therefore, in order to light a large number of discharge tubes with a low output voltage, a power supply device in which the output sides are connected in parallel and capable of parallel lighting is used.

[0004]

When the discharge lamp ballast is used for installation work, the maximum output voltage of the ballast is 100
The construction method varies greatly depending on whether or not it exceeds 0V.
If it exceeds 1000V, the construction becomes troublesome, the construction period becomes long, the construction cost becomes high, and only a highly qualified construction person can do it. Therefore, users require a ballast with a rating of 1000 V or less and a high lighting capability, but the maximum output voltage is legally defined as a rating, so the maximum output voltage is 1 for simple construction.
I had to keep it below 000V. in this case,
Since the output voltage when the discharge tube is lit is 300 to 500 V, that is, half or less of the no-load voltage, only the argon tube having a low discharge start voltage can be lit and the discharge start voltage is 100%.
It was not possible to light the neon tube close to 0V.

[0005]

According to the present invention, the current of the high frequency inverter circuit is detected by the current detecting means, and means for stopping the oscillation of the high frequency inverter circuit is provided when the detected current becomes a predetermined value or less. .

[0006]

According to the structure of the present invention, when the circuit connected to the output side is disconnected or the gas in the discharge tube is degassed and the output side becomes unloaded, no current flows in the high frequency inverter circuit and When the voltage tries to become extremely high, it is detected that the current of the high frequency inverter circuit has dropped below a predetermined value, and the oscillation of the high frequency inverter circuit is stopped. Therefore, there is no possibility of generating a high no-load voltage on the output side. .

[0007]

FIG. 1 shows an embodiment of the present invention. Input terminal 1
A full-wave rectifier circuit 13 is connected between 1 and 12, whereby, for example, commercial alternating current is rectified. The rectifier circuit 13
A series circuit of capacitors 14 and 15 is connected to the output side of, and a series circuit of FETs 16 and 17 as switching elements is connected. The output transformer 1 is provided between the connection point of the capacitors 14 and 15 and the connection point of the FETs 16 and 17.
8 primary coils are connected. A parallel circuit of a capacitor 19 and a resistor 21 is connected across the output side of the full-wave rectifier circuit 13, and the positively charged side of the capacitor 19 is connected to the power supply terminal (terminal number 12) of the IC 22 of the switching regulator. ), And the negative side is connected to the ground terminal (No. 7). A capacitor 23 and a tunneler diode 24 are connected in parallel between the power supply terminal and the ground terminal of this IC 22. The switching output terminal (terminal number 10) of the IC 22 is connected to the primary side of the pulse transformer 26 through the capacitor 25. Pulse transformer 2
Both ends of the secondary coils 27 and 28 of 6 are FET1 respectively.
It is connected to the gate sources 6 and 17.

When AC power is applied between the input terminals 11 and 12 and the voltage of the capacitor 19 reaches a predetermined voltage, the voltage between the power supply terminal of the switching regulator IC 22 and the ground terminal becomes a voltage determined by the zener diode 24, and the IC
22 oscillates, the pulse transformer 26 turns on the FET 16 by the rising pulse of the oscillation output rectangular wave signal, turns on the FET 17 by the rising pulse, and FE
By alternately turning on T16 and T17, the capacitors 14 and 15 are alternately discharged through the output transformer 18, and high frequency power is output from the output transformer 18. The output transformer 18 is provided with a third winding 29,
When the output of the winding 29 is applied between the power supply terminal and the ground terminal of the IC 22 through the diode 31 and the oscillation of the high frequency inverter circuit 32 is started, a part of the output is passed through the third winding 29. Further, through the diode 31,
It is supplied to C22 as operating power.

In this embodiment, the high frequency inverter circuit 32
Capacitor 15 and FET to detect the current of the
A current detection resistor 35 is inserted in series between the connection point of 17 and the negative output side of the full-wave rectification circuit 13, and a diode 36 is provided at one end of the current detection resistor 35 on the capacitor 15 side. The anode side is connected, and a parallel circuit of a capacitor 37 and a resistor 38 is connected between the cathode of the diode 36 and the other end of the current detection resistor 35. The base and emitter of the transistor 39 are connected in parallel with this parallel circuit. The collector of the transistor 39 is connected to the terminal number 15 of the IC 22. The reference voltage generated in the IC 22 is applied to the terminal number 13 of the IC 22. Between the terminal number 13 and the ground, a resistor 41,
The series circuit of 42 and the series circuit of the resistors 43 and 44 are connected, and the connection point of the resistors 41 and 42 is the transistor 39.
And a capacitor 45 connected in parallel with the resistor 42. The connection point of the resistors 43 and 44 is IC2.
2 is connected to terminal number 16. The IC 22 includes terminals 3 and 4 and capacitors and resistors respectively connected to the ground, and terminals 5 and 13 respectively.
The oscillation frequency is set by the resistor connected between and. Further, both inputs of the terminal numbers 15 and 16 are internally compared by a comparator, and the oscillation is stopped when the input of the terminal number 15 becomes larger than the input of the terminal number 16.

In this configuration, two output transformers 18 are provided.
One end of each of the capacitors 51 to 54 as a current limiting element is connected to one end of the next coil, and a discharge tube such as a neon lamp is provided between the other end of the secondary coil of the transformer 18 and the other end of each of the capacitors 51 to 54. The tubes 55, 56 and 57 are connected, and in this example, a discharge tube is not connected between the other end of the capacitor 54 and the other end of the secondary coil of the transformer 18 but is short-circuited. In this way, the discharge tubes are connected in parallel to the secondary side of the output transformer 18 via capacitors as current limiting elements.
That is, even if the output side at the location of the capacitor 54 is short-circuited as in this example due to the impedance of the capacitors 51 to 54, the presence of the impedance in the capacitor 54 causes the other discharge tubes 55 to 57.
The voltage that keeps lighting is maintained.

In this configuration, when the neon tubes 55 to 57 are turned on by the output voltage of the output transformer 18, the current flowing through the high frequency inverter circuit 32 is relatively large, that is, the current detecting resistor 35 has both ends. The voltage drop that occurs is relatively large and therefore the diode 36
The voltage stored in the capacitor 37 via is relatively high, and the transistor 39 is in the ON state. Therefore, IC22
The terminal No. 15 has a ground potential, which is lower than the voltage of the terminal No. 16, so that the IC 22 holds the oscillation state.

However, when the output side of the output transformer 18 approaches a no-load state for some reason, the current flowing through the high frequency inverter circuit 32 decreases and the current detecting resistor 3
The voltage across the terminal 5 becomes small, the transistor 39 is turned off, the voltage at the terminal number 15 of the IC 22 becomes larger than the voltage at the terminal number 16, and the oscillation of the IC 22 stops. Therefore, there is no fear that a high voltage will be generated from the output transformer 18. Even if the discharge start voltage of the neon tube is lower than 1000 V but close to this, the discharge can be started at a voltage of 1000 V or lower, and a no-load state occurs, and as described above, the inductance of the output transformer 18 is increased. Even if a resonance phenomenon occurs due to the current limiting capacitor or the stray capacitance of the neon tube, the current of the high-frequency inverter circuit 32 decreases due to the no-load state before the high voltage, and the oscillation is stopped. Output voltage is 100
It never exceeds 0V. That is, according to this configuration, the output voltage does not exceed 1000V even if the ballast has a capacity corresponding to 2000V when no load is applied, and thus the ballast can be used as a ballast having a rating of 1000V or less.

FIG. 2 shows another embodiment of the present invention. In this example, the current transformer 61 is inserted in series with the secondary coil of the output transformer 18, the both ends of the parallel circuit of the resistor 62 and the capacitor 63 are connected to the secondary side of the current transformer 61, and one end thereof is It is connected to the ground terminal and the other end is connected to the base of the transistor 39 through the diode 36. In this case, the collector of the transistor 39 is IC
22 is connected to the 14th terminal, the 14th terminal is I
Inside the C22, the reference voltage of 1.3V is compared with the comparator, and the oscillation is stopped when the voltage of the 14th terminal becomes higher than 1.3V.

In this configuration, when operating normally, the current of the high frequency inverter circuit 32 is large and the output of the current transformer 61 is also large, so that the transistor 39 is kept in the ON state, and therefore the IC 22 of the IC 22 is maintained. The applied voltage inside the terminal number 14 is extremely small, and the oscillation of the IC 22 is maintained. When the output side of the output transformer 18 becomes unloaded and no current flows, the transistor 39 turns off and I
The voltage of the terminal number 14 of C22 becomes higher than 1.3V,
There is no possibility that the oscillation of the IC 22 will stop and a high voltage will be generated on the output side of the output transformer 18.

Although the present invention is applied to the case where the separately excited high frequency inverter circuit is used in the above, the present invention can also be applied to a power supply device using a self excited high frequency inverter circuit. An example thereof is shown in FIG. 3 in which parts corresponding to those in FIG. The output side of the full-wave rectifier circuit 13 is supplied to the smoothing circuit 65, one end of the output side of the smoothing circuit 65 is maintained at the midpoint of the primary winding 67 of the output transformer 66, and the other end of the output side of the smoothing circuit 65 is It is connected to both ends of the primary winding 67 through FETs 68 and 69 as switching elements. A series circuit of a diode 71, a resistor 72 and a capacitor 74 is connected across the output side of the smoothing circuit 65, and a zener diode 74 is connected across the capacitor 74 via a resistor.
The resistance voltage dividing circuits 75 and 76 are connected in parallel between both ends of
The voltage dividing points of the resistance voltage dividing circuits 75 and 76 are FETs 68 and 69.
Is connected to the gate of and is supplied with a bias voltage. These gates are connected to both ends of the feedback winding 77 of the output transformer 66. The discharge lamps 55 to 56 are connected to the secondary winding 78 of the output transformer through the current limiting capacitors 51 to 53, respectively.

A current detection resistor 35 is inserted in series between the input side of the self-excited high frequency inverter circuit 79 and the negative output side of the smoothing circuit 65, and the resistor 35 drops as in the case of FIG. The base and emitter of the transistor 39 are connected to both ends of the capacitor 37 which is charged with voltage, the collector of the transistor 39 is connected to the cathode side of the Zener diode 74 through the resistors 81 to 82, and the base of the transistor 83 is connected to both ends of the resistor 82. , The collector is connected, and the emitter of the transistor 83 is a resistor 84-
Is connected to the anode of the Zener diode 74 through 85, and the capacitor 86 is connected in parallel with the resistor 85,
A thyristor 87 is connected across the Zener diode 74, and the gate of the thyristor 87 is connected to the connection point of the resistors 84 and 85.

When a relatively large high-frequency current flows through the high-frequency inverter circuit 79, the transistor 39 is turned on, the transistor 83 is turned off, and the thyristor 87 is turned off, as described above. However, the load of the output transformer 66 becomes close to no load, and the inverter circuit 79
When the high-frequency current of is significantly reduced, the transistor 39 is turned off, the transistor 83 is turned on, a voltage is applied to the gate of the thyristor 87, the thyristor 87 is also turned on, both ends of the zener diode 74 are short-circuited, and the FETs 68 and 69 are turned on. The proper bias is not given, and F
ET68 and 69 remain off, output transformer 66
There is no risk of abnormally high voltage being generated on the output side of. Also in this self-exciting high-frequency inverter circuit 79, the current transformer 61 is inserted on the output side and the output thereof is charged in the capacitor 37 in FIG. 3 to prevent the abnormal high voltage from occurring. Good.

[0018]

As described above, according to the present invention, in the steady operation state, that is, in the loaded state,
The output voltage of the output transformer is 1000V or less, but even if it is set to a value close to this, if there is no load, the output current will disappear and this will be detected to stop the oscillation of the high frequency inverter circuit. In addition, no no-load abnormal voltage is generated on the output side, and therefore even a high discharge starting voltage such as a neon tube can be installed as a construction of 1000 V or less, and can be constructed at low cost.
The construction period is short, construction is easy, and there is no need for highly qualified construction personnel.

[Brief description of drawings]

FIG. 1 is a connection diagram showing an embodiment to which the present invention is applied when a separately excited high frequency inverter circuit is used.

FIG. 2 is a connection diagram showing another embodiment.

FIG. 3 is a connection diagram showing an embodiment in which the present invention is applied when a self-excited high-frequency inverter circuit is used.

Claims (5)

[Claims] 1. A high-frequency power supply device for parallel multi-lamp lighting, wherein a plurality of discharge lamps are connected in parallel to each other on the output side of the high-frequency inverter circuit via current limiting elements, and means for detecting the current of the high-frequency inverter circuit. And a means for stopping the oscillation of the high-frequency inverter circuit when the detected current becomes a predetermined value or less. 2. The means for detecting the current comprises a current detection resistor inserted in series between one end of the high frequency inverter circuit on the input side and one end of the input DC power supply, and a resistor for detecting the current. The high-frequency power supply device for parallel multi-lamp lighting according to claim 1, wherein the voltage between both ends comprises a capacitor charged through a unidirectional element. 3. The current detecting means is a current transformer coupled to a secondary circuit of an output transformer provided on the output side of the high frequency inverter circuit, and a rectifier rectifying the output of the current transformer. The high frequency power supply device for parallel multi-lamp lighting according to claim 1, characterized in that the rectified output comprises a capacitor charged. 4. The high-frequency inverter circuit is a separately excited type, and the means for stopping the oscillation is means for stopping the oscillation of the oscillation circuit for exciting the high-frequency inverter circuit when the voltage of the capacitor becomes a predetermined value or less. The high frequency power supply device for parallel multi-lamp lighting according to claim 2 or 3, wherein 5. The high-frequency inverter circuit is a self-excited type, and the means for stopping the oscillation is means for short-circuiting the bias circuit of the high-frequency inverter circuit when the voltage of the capacitor becomes a predetermined value or less. The high frequency power supply device for parallel multiple lamp lighting according to claim 2 or 3.