JPH0660989A - No-electrode electric discharge lamp lighting device - Google Patents

Abstract

PURPOSE:To stabilize the operation of a starting circuit, and improve reliability by arranging a starting coil or a pressure increasing transformer constituting the resonance circuit part of the starting circuit so as to be surrounded with the fins of a heat sink. CONSTITUTION:An excitation coil 7 is connected to an output terminal of an inverter through a capacitor 8, and in a no-electrode electric discharge lamp 14, the excitation coil 7 is wound round the outer peripheral part of a lamp tube, and at least dischargeable gas or vapor is sealed up in the lamp tube. The capacitor 8 is formed by sandwiching an insulating material between metallic plates formed integrally with the excitation coil 7, and is connected in parallel to the excitation coil 7, and heat sinks 23a and 23b are arranged so as to come into close contact with the metallic plate surface of the capacitor 8 to radiate heat of the excitation coil 7 and the capacitor 8. A resonance circuit part having a starting coil 10 is connected in parallel to the excitation coil 7, and a starting circuit is provided to impress starting high voltage upon the no-electrode electric discharge lamp 14, and the starting coil 10 is arranged so as to be surrounded with the fin of the heat sink 23b under earth electric potential.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrodeless discharge lamp lighting device for lighting a lamp by magnetically supplying high-frequency power from an excitation coil wound around the electrodeless discharge lamp to a plasma ring in the lamp. In particular, the present invention relates to an electrodeless discharge lamp lighting device capable of stabilizing a starting circuit.

[0002]

2. Description of the Related Art In particular, an electrodeless discharge lamp driven at high frequency is a discharge lamp having excellent characteristics such as high efficiency, high brightness, high color rendering and long life. In order to light this electrodeless discharge lamp, in addition to an excitation coil wound around the lamp, a starting circuit for generating a high voltage is required. The block diagram of FIG. 5 shows a conventionally known lighting device for lighting this electrodeless discharge lamp. In this figure, a commercial AC power supply 1 is converted into a DC power supply by a rectifier circuit 2 and then converted into a high frequency power supply of 13.56 MHz by an inverter 3. The inverter 3 is formed in a half bridge type including switching elements 5a and 5b driven by a drive circuit 4. An excitation coil 7 is connected between the output terminals of the inverter 3 via a first capacitor 6, and a second capacitor 8 is connected in parallel to the excitation coil 7 which constitutes the main circuit. The excitation coil 7 is wound around the lamp 14 for several turns (for example, 2 turns). Here, the capacitors 6 and 8 constitute a resonance circuit together with the excitation coil, and also perform impedance correction for matching the high frequency power supply and the lamp load. The capacitor 8 is formed by sandwiching an insulating sheet between two aluminum plates integrated with the excitation coil 7. The excitation coil 7 is heated by radiant heat from the lamp 14 and its own Joule heat. The capacitor 8 is also heated by its own Joule heat, dielectric loss, and conduction heat from the excitation coil 7. The temperature rise due to this heating not only causes the excitation coil 7 and the capacitor 8 to change with time, but also causes the inductance of the coil 7 and the capacitance of the capacitor 8 to fluctuate, disturbing the matching conditions between the lamp load and the ballast. , Interfere with normal operation. Therefore, a heat sink is provided in close contact with the aluminum plate forming the capacitor 8, and the excitation coil 7 and the capacitor 8 are cooled by this heat sink. Further, the excitation coil 7 has a third capacitor 9,
A starting circuit 13A configured by a series circuit including a parallel resonance circuit section of the starting coil 10 and the fourth capacitor 11 and a starting switch 12 is connected in parallel. A high voltage generation point P, which is a connection point between the capacitor 9 and the parallel resonant circuit section, is connected to the gas probe 14b of the lamp 14 via the starting electrode 31. Here, the capacitors 9 and 11 are used for tuning. By changing the degree of resonance of the starting circuit 13A by the capacitors 9 and 11, the distribution of electric power to the main circuit and the starting circuit 13A is changed or the starting circuit operation is performed. It has a function of matching the combined impedance of the main circuit and the starting circuit 13A therein with the high frequency power supply. Electrodeless discharge lamp 1
No. 4 contains 250 krypton (Kr) which is a discharge gas in the main tube 14a which is an arc tube.
Enclosed with torr, NaI, C
eI is enclosed. From the top of the main tube 14a, a gas probe 14b forming a starting energy injection pipe section separated from the main tube 14a by a partition wall extends. 10 krypton is contained in the probe 14b.
About torr is included.

In the electrodeless discharge lamp lighting device configured as described above, when the switch 12 is turned on at the time of starting to supply high frequency power from the inverter 3 to the main circuit and the starting circuit 13A, the high voltage generated in the starting circuit 13A is generated. It is applied to the gas probe 14b. Thereby, the gas probe 14b
The gas in the main tube 14a is destroyed by the discharge, and the gas in the main tube 14a is brought into a glow discharge state.
A plasma ring is formed in 4a. When the formation of the plasma ring is detected by a detection circuit (not shown), the start switch 12 is turned off in response to the detection signal. After that, lighting power is supplied from the excitation coil 7 to the magnetically coupled plasma ring, and the lamp 14 is lit at high frequency.

Incidentally, in order to generate a high voltage for starting, a starting circuit 13B using a step-up transformer T as shown in FIG. 6 is also known, instead of using the resonance circuit shown in FIG. There is. In this starting circuit 13B, a series circuit including a capacitor 9, a primary winding T1 of the step-up transformer T, a parallel resonance circuit portion of the capacitor 11, and a starting switch 12 is connected in parallel to the excitation coil 7, and the secondary circuit of the step-up transformer T is connected. A high voltage for starting can be applied to the gas probe 14b from a high voltage generation point P of the winding T2.

[0005]

By the way, in such a conventional lighting device, in order to increase the voltage generated at the point P which is the starting voltage extracting point, the starting coil 10 or the primary winding of the step-up transformer T is increased. The inductance of T1 must be increased and the capacitance of the capacitor 9 must be decreased. This means that the starting circuits 13A and 13B are greatly affected by the slight stray capacitance appearing in parallel with the capacitors 9 and 11. In addition, the starting circuit 13A,
A high voltage cannot be generated at point P unless 13B is set to a series resonance condition or a condition close to this, so a relatively large current flows through the starting coil 10 and the primary winding T1 of the step-up transformer T. This is the starting coil 10 and the primary winding T
The magnetic lines of force formed by 1 combine with other ballast components, and cause unstable operation.

The present invention has been proposed in order to solve the problems of the prior art, and an object thereof is to provide an electrodeless discharge lamp lighting device capable of stabilizing the operation of a starting circuit. .

[0007]

In order to achieve this object, an electrodeless discharge lamp lighting device according to the present invention comprises an inverter for converting a DC power supply into a high frequency power supply and a first capacitor between the output terminals of this inverter. An excitation coil connected through the lamp tube, an electrodeless discharge lamp in which the excitation coil is wound around the outer periphery of the lamp tube, and at least a discharge gas or vapor is sealed in the lamp tube, and a metal plate integrated with the excitation coil. A second capacitor, which is formed by sandwiching an insulating material between and is connected in parallel to this exciting coil, and a metal plate surface which constitutes this second capacitor in order to dissipate heat from the exciting coil and the second capacitor. The heat sink closely attached to the and the resonance circuit unit having the starting coil or the resonance circuit unit having the step-up transformer is connected via the starting switch. Connected in parallel with said excitation coil,
A starting circuit for applying a high starting voltage to the electrodeless discharge lamp is provided, and the starting coil or the step-up transformer of the starting circuit is arranged so as to be surrounded by the fins of the heat sink at ground potential. ing.

[0008]

According to the above-mentioned structure, the starting coil or the step-up transformer of the resonance circuit section can be surrounded by the fin (conductor) of the heat sink, which is at the ground potential.
The influence of the stray capacitance is eliminated, and the surrounding circuit elements are not affected by the magnetic flux generated by the starting coil and the primary winding of the step-up transformer.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of the electrodeless discharge lamp lighting device according to the present invention will be described in detail below with reference to the drawings. In the description, the same parts as those in the conventional example are designated by the same reference numerals, and the description of the overlapping parts will be partially omitted. An example of this lighting device is shown in the block diagram of FIG. In this figure,
An excitation coil 7 is connected via a first capacitor 6 between output terminals of a half-bridge type inverter 3 which converts a DC power source into a high frequency power source and takes out the second capacitor 8 in parallel with the excitation coil 7. Are connected.

At both ends of the excitation coil 7, a series-parallel resonance circuit is formed by connecting a parallel resonance circuit section 16 including a starting coil 10, a fourth capacitor 11 and a damping resistor 15 in series to a third capacitor 9. , Starting switch 12
Are connected in parallel via. Damping resistor 15
Has a function of lowering Q (sharpness) of the parallel resonant circuit section 16. A connection point P between the third capacitor 9 and the parallel resonance circuit section 16 which is a high voltage generating point is connected to the gas probe 14b which is the starting energy injection tube section of the electrodeless discharge lamp 14 through the starting electrode 31. Has been done. Here, the third capacitor 9, the parallel resonant circuit section 16 and the starting switch 12 constitute a starting circuit 18. A noise filter may be provided between the commercial AC power supply 1 and the rectifier circuit 2, and a low distortion input power supply circuit may be provided between the rectifier circuit 2 and the inverter 3.

Next, the concrete construction of the main circuit and the starting circuit of the lighting device will be described with reference to FIGS. 2 and 3. In the capacitor 6 connected in series with the inverter 3,
A monolithic ceramic high voltage capacitor is used. Lamp 1
The capacitor 8 connected in parallel to the excitation coil 7 wound around the coil 4 is a 65 × 130 mm aluminum plate 2 which is integrated with the coil 7.
Copper plates 21a and 21b having a thickness of 0.1 mm between 0a and 20b
With a thickness of 0.35m between the copper plates 21a and 21b.
It is configured by sandwiching an insulating sheet 22 made of a fluororesin sheet or the like. In addition, the aluminum plate 20a,
Heat sinks 23a and 23b are attached in close contact with the surface of 20b. The heat sink 23b on the ground potential side is provided with a coil housing portion 25 formed by cutting out a part of the fin 24. The capacitor 9 is formed between the copper disk 26 and the aluminum plate 20a on the high voltage side, and an insulating sheet 27 such as a fluororesin sheet is attached to the lower surface of the copper disk 26. This copper disc 2
An adjusting screw 28 is attached to 6 via a bar 29. By changing the position of the copper disk 26 with this adjusting screw 28, the capacitance of the capacitor 9 can be finely adjusted. 30 is a spacer. The bar 29 connected to the copper disk 26 is connected to the starting coil 10 and also to the gas probe 14b of the lamp 14 via the starting electrode 31. The other end of the starting coil 10 is connected to the ground side of the main circuit via a relay RY that forms a starting switch 12. Between the bar 29 and the ground,
A damping resistor 15 is connected. The starting coil 10 is placed in a coil housing portion 25 formed in the heat sink 23b, and the coil 10 is surrounded by the fins 24 of the heat sink 23b at the ground potential. By thus storing the starting coil 10 in the conductor of the ground potential, it is possible to prevent an increase in stray capacitance, shield the magnetic flux generated from the coil 10, and influence the surrounding circuit elements by the magnetic flux of the coil 10. I will not receive it. In addition, the starting coil 10 is attached to the heat sink 2
The housing in 3b can shorten the distance to the gas probe 14b, and can suppress the loss of the starting power radiated from the high voltage line into the air and lost. As a result, the operation of the starting circuit 18 can be stabilized. An insulating sheet is sandwiched between the aluminum plate 20a on the high voltage side and the heat sink 23a to insulate the heat sink 23a and the heat sink 2
If 3a is set to the ground potential, the starting coil 10 can be housed in the coil housing portion formed on the heat sink 23a.

Next, the operation of the electrodeless discharge lamp lighting device at the time of starting will be described. When the lamp 14 is to be started, the starting switch 12 is turned on and power is supplied from the inverter 3 to the main circuit and the starting series-parallel resonance circuit. As a result, the high voltage appearing at the high voltage generation point P is applied to the gas probe 14b of the lamp 14, so that glow discharge is induced in the main tube 14a, and energy is received from the excitation coil 7 and the main tube 14a is received. One turn of the plasma ring is formed at. When the formation of the plasma ring is detected, the starting switch 12
Is opened, and electric power for lighting is supplied to the inside of the main tube 14a through the plasma ring magnetically coupled to the excitation coil 7. In this lighting device, the operation of the starting circuit 18 is stable, and a sufficiently high starting voltage can be taken out to the voltage generation point P, so that the lamp can be started well and the transition to the lighting state can be performed well thereafter. .

FIG. 4 shows the constants of each element used in the actual device for the two examples of the first example and the second example. Here, the electrostatic capacities of the capacitors 6 and 8 are Cs and Cp.
And the inductance of the excitation coil 7 is L, the coil 7
The internal resistance of R is R. Further, the inductance of the starting coil 10 is Lst, the electrostatic capacities of the capacitors 9 and 11 are Cstp and Csts, respectively, and the resistance value of the resistor 15 is Rst.

The present invention can also be applied to a lighting device having a starting circuit 13B using a step-up transformer T as shown in FIG.

[0015]

As described above, according to the present invention, since the starting coil and the step-up transformer forming the resonance circuit section of the starting circuit are arranged so as to be surrounded by the fins of the heat sink at the ground potential, the stray capacitance is reduced. And the magnetic flux generated from the coil and the transformer can be shielded, and the surrounding circuit elements are not affected by this magnetic flux. As a result, the operation of the starting circuit can be stabilized, and the deviation of the resonance condition and the matching deviation do not occur, so that the reliability of the device can be improved. In addition, the high voltage necessary for starting the lamp can be stably generated and a large starting current can be passed, so that the lamp can be started well. Further, since the starting coil and the step-up transformer can be arranged in the vicinity of the discharge lamp, the extension of the high voltage line to the lamp can be shortened and the loss of the starting electric power leaked from the high voltage line into the air by radiation can be suppressed. Also, the fact that the starting coil and the step-up transformer can be housed in the heat sink is advantageous in terms of space saving.

[Brief description of drawings]

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

FIG. 2 is a schematic side view showing a specific configuration of a main circuit and a starting circuit portion of this lighting device.

FIG. 3 is a schematic plan view showing a specific configuration of a main circuit and a starting circuit portion of the lighting device.

FIG. 4 is a diagram showing constants of respective elements used in the lighting device of FIG.

FIG. 5 is a block diagram showing an example of a conventional electrodeless discharge lamp lighting device.

FIG. 6 is a circuit diagram showing another starting circuit.

[Explanation of symbols]

 1 Commercial AC Power Supply 2 Rectifier Circuit 3 Inverter 4 Drive Circuit 5a, 5b Switching Element 6 First Capacitor 7 Excitation Coil 8 Second Capacitor 9 Third Capacitor 10 Starting Coil 11 Resonating Capacitor 12 Starting Switch 14 None Electrode discharge lamp 14a Main tube 14b Gas probe 15 Damping resistance 16 Parallel resonance circuit part 18 Starting circuit 20a, 20b Aluminum plate 21a, 21b Copper plate 22 Insulation sheet 23a, 23b Counter electrode 24 Fin 25 Coil storage part 26 Copper disc 27 Insulation sheet 28 Adjustment screw 29 Bar 30 Spacer 31 Starting electrode

Claims (1)

[Claims] 1. An inverter for converting a direct-current power supply into a high-frequency power supply, an excitation coil connected between output terminals of the inverter via a first capacitor, and a lamp tube, wherein at least a discharge characteristic is provided in the lamp tube. It is formed by inserting an insulating material between an electrodeless discharge lamp that is filled with gas or vapor and that discharges by the magnetic flux generated by the excitation coil, and a metal plate that is integral with the excitation coil, and is connected in parallel to this excitation coil. A second capacitor, a heat sink closely attached to a metal plate surface of the second capacitor for radiating heat from the excitation coil and the second capacitor, and a resonance circuit section or a step-up transformer having a starting coil. A resonance circuit section having a start switch is connected in parallel to the excitation coil through a starting switch, and an electrodeless discharge lamp has a high starting voltage. And a starting circuit for applying a pressure, the starting coil or step-up transformer of the starting circuit, the electrodeless discharge lamp lighting apparatus, characterized in that arranged so as to be surrounded by the fins of the heat sink to the ground potential.