JPH10106775A - Electrodelessdischarge lamp lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrodeless discharge lamp lighting device capable of stably discharging an electrodeless discharge lamp, making the device small, and enhancing efficiency. SOLUTION: In an electrodeless discharge lamp in which a metal cylinder having an opening in the innermost recess of an indent of a bulb 1 is inserted between the bulb 1 and an induction coil 2, high &equency current flowing through the induction coil 2 is detected with a detecting circuit X through a current transformer CT, a switching element SWI in a matching circuit 6 is controlled with a switching circuit Y, and thereby, voltage for generating high frequency electric field ' discharge in the induction coil 2 is switched to voltage for generating high frequency electromagnetic field discharge, and both voltages are generated in the optimum condition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electrodeless discharge lamp lighting device, and more particularly to an electrodeless low-pressure discharge lamp lighting device.

[0002]

2. Description of the Prior Art As a first conventional example according to the present invention, FIG.
FIG. 1 is a front view of a conventional electrodeless low-pressure discharge lamp partially cut away, and will be briefly described below.

[0003] The electrodeless low-pressure discharge lamp L has a substantially spherical bulb 1.
And the induction coil 2 is arranged in a recess at the approximate center. When a high-frequency current (for example, 2.65 MHz) is generated by the inverter device and the high-frequency current is supplied to the induction coil 2, a high-frequency electromagnetic field is generated from the induction coil 2, and the high-frequency electromagnetic field is set inside the induction coil 2. The ferrite 10 is magnetically coupled with the ferrite 10 to generate a magnetic field, and supplies a high-frequency electromagnetic field to the discharge plasma 4 in the bulb 1 disposed outside the induction coil 2 so that low-pressure mercury as the discharge plasma 4 Ultraviolet rays are radiated, the ultraviolet rays are converted into visible light by the phosphor 9, and the electrodeless low-pressure discharge lamp L is turned on.

[0004] However, the first conventional example has the following problems. The ferrite 10 plays an important role in supplying the high-frequency electromagnetic field from the induction coil 2 to the discharge plasma 4 in the electrodeless low-pressure discharge lamp L. The induction coil 2 and the ferrite 10 are wrapped in the bulb 1 that generates heat, and the induction coil 2 and the ferrite 10 themselves generate heat, causing power loss. In particular, the power loss of the ferrite 10 increases as the temperature increases. Therefore, the heat loss of the ferrite 10 is suppressed by using a heat pipe 11 made of a copper rod. When a high-frequency electromagnetic field is also applied to an air-core coil (not shown) that does not use the ferrite 10, power loss occurs due to internal resistance, and the internal resistance of the air-core coil increases with temperature. I do. When the resistance value increases, the power loss increases and the luminous flux decreases. In addition, when the electrodeless low-pressure discharge lamp L shifts to the lighting state, heat radiation from the bulb 1 itself starts, and the heat is conducted to the adjacent metal parts such as the induction coil 2 and the ferrite 10 heat pipe 11 to generate power loss. This leads to a further reduction in the luminous flux.

When starting with a high frequency discharge of several MHz to several tens of MHz, a high frequency electric field discharge (glow discharge) is first generated in the bulb 1 by a high frequency electric field, and then a high frequency electromagnetic field discharge (glow discharge) is generated by a high frequency electromagnetic field. (Arc discharge) occurs, and the electrodeless low-pressure discharge lamp L shifts to a lighting state. When the metal tubular body 3 to be discharged has a loop of a metal or the like in the direction of the induction electric field of the high-frequency electromagnetic field near the air-core coil, a high-frequency eddy current is generated in the metal, resulting in a power loss. When the discharge plasma 4 is not generated, such as when the electric lamp L is started, the starting electric power may be combined with the metal near the induction coil 2 to make starting difficult. Since the eddy current is generated in the loop-shaped metal shield, if the metal cylindrical body 3 is formed into a loop, an induced electric field is generated in the loop, and power is consumed, and the electrodeless low-pressure discharge lamp L is started. Power cannot be supplied, and the luminous flux is also impaired.

Further, at the start of the high-frequency discharge, if a metal plate having the same potential as the ground side of the lighting circuit 8 (not shown) is inserted between the induction coil 2 and the bulb 1 containing the discharge plasma 4, the induction coil 2 generates There is a problem that the high-frequency electric field is shielded, and it is difficult to shift to the electric field discharge.

Furthermore, in the electrodeless low-pressure discharge lamp L,
The induction discharge forms a discharge loop in the bulb 1 and forms a discharge plasma 4 at a certain distance from the tube wall on which the phosphor 9 is applied. The high-frequency high-field discharge tends to be generated in the phosphor 9 in the bulb 1 near the induction coil 2 for supplying the high-frequency high electric field, causing the phosphor 9 to blacken, which shortens the lamp life. There are also problems.

In order to solve all the problems in the first conventional example, in other words, as a second conventional example according to the present invention, Japanese Patent Application No. 8-37989 filed by the applicant of the present invention.
There are those shown in FIG. 5, which are shown in FIG. In FIG.
A front view in which the electrodeless low-pressure discharge lamp L is partially cut away is shown, and will be briefly described below. Note that portions corresponding to FIG. 4 showing the first conventional example are denoted by the same reference numerals as those shown in FIG.

In this conventional example, the lighting circuit 8 is connected to the cable 7
, High-frequency power flows to the matching circuit 6 in the base 5. A circuit that matches the induction coil 2 and the electrodeless low-pressure discharge lamp L at the time of lighting and starting is set on the matching circuit 6. When high-frequency power flows from the matching circuit 6 into the induction coil 2, a high-frequency electromagnetic field is generated from the induction coil 2,
Discharge plasma 4 is formed in bulb 1. here,
An air-core coil is used as the induction coil 2 instead of the ferrite 10 that generates heat as shown in the first conventional example. Since the heat source is the air-core coil (induction coil 2) and the electrodeless low-pressure discharge lamp L itself, a metal shield (metal cylindrical body) is provided between the bulb 1 and the induction coil 2 as shown in FIG. Insert 3). The metal shield is in thermal contact with the heat radiating portion outside the electrodeless low-pressure discharge lamp L,
Heat generated from the induction coil 2 and the electrodeless low-pressure discharge lamp L is radiated from the radiator through the metal shield. Thereby, the heat transmitted from the electrodeless low-pressure discharge lamp L itself to the induction coil 2 is reduced, and the heat generated from the induction coil 2 itself is also reduced, so that the internal resistance of the induction coil 2 is reduced. As a result, the power lost in the induction coil 2 decreases, so that the power transmitted to the electrodeless low-pressure discharge lamp L increases and the luminous flux increases. Since the metal shield also has an effect of blocking a high-frequency electric field, it has an effect of suppressing a high-frequency electromagnetic field that causes blackening of the phosphor 9 and extends the life of the lamp.

Further, as shown in FIG. 5, by providing a slit 3a in a direction substantially perpendicular to the winding direction of the induction coil 2, a metal loop generated from the induction coil 2 in the metal tubular body 3 is formed by the slit 3a. And the coupling of the high-frequency electromagnetic field in the metal cylindrical body 3 becomes extremely low, so that more high-frequency electromagnetic fields are supplied to the discharge plasma 4 and the loss of the high-frequency power supplied to the bulb 1 is reduced. There is an advantage that the light flux is increased and the light flux is increased.

Next, FIG. 6 shows a change in the induction coil voltage Vc applied to both ends of the induction coil 2 from the start to the lighting of the electrodeless low-pressure discharge lamp L.
The state from start-up to lighting is briefly described.

First, at time to, the voltage V
When E is applied, a high-frequency electric field discharge (also referred to as E discharge... Is classified systematically by Babat) occurs in the electrodeless low-pressure discharge lamp L. At time t1, by applying a voltage VH higher than the voltage VE to the induction coil 2, a high-frequency electromagnetic field discharge (also referred to as H discharge... Is systematized and classified by Babat) in the electrodeless low-pressure discharge lamp L. Occurs, and at time t2, the electrodeless low-pressure discharge lamp L shifts to a lighting state, and a voltage lower than the voltage VE is applied to the induction coil 2. 6 shows that VE <VH (1) VE period (between t0 and t1) <VH period (between t1 and t2) (2) However, this conceptually indicates that the discharge plasma generated in the bulb 1 may have lower electric energy in the high-frequency electric field discharge than in the high-frequency electromagnetic field discharge.

The high-frequency electric field discharge has a large correlation with the distance (1 shown in FIG. 5) from the induction coil 2 to the inner wall of the bulb 1. As the distance from the induction coil 2 to the inner wall of the bulb 1 increases, the high-frequency electric field discharge increases. The voltage VE that causes discharge increases. In addition, the induction coil 2 in contact with the metal cylindrical body 3
Is shielded by the metal tubular body 3 and does not contribute to the high-frequency electric field discharge. The high-frequency electric field by the induction coil 2 which is in contact with the inner wall of the bulb 1 and is not covered by the metallic tubular body 3, that is, The high-frequency electric field generated by the coil top portion 2C shown in FIG. 5 contributes to the high-frequency electric field discharge. From the above, it can be seen that if the distance between the coil top portion 2C and the inner wall of the bulb 1 is long, the coil voltage VE for generating high-frequency electric field discharge is large, and if the distance is short, the coil voltage VH is small.

[0014]

However, the second conventional example has the following problems.

Depending on the design of the electrodeless low-pressure discharge lamp L, the induction coil 2 and the metal cylinder 3, for example, the coil top 2C
When the distance between the electrode and the inner wall of the bulb 1 increases, and VE> VH... (3). FIG. 7 shows a change in the induction coil voltage Vc.

In this case, the electric energy amount WE = VE × (t0−t1) for generating the high-frequency electric field discharge and the electric energy amount WH = V for generating the high-frequency electromagnetic discharge.
Even if the relationship with H × (t2−t1) is WE <WH... (4), the lighting circuit 8 needs to satisfy Expression (3) and therefore has a large capacity. Is required, which leads to an increase in the size of the lighting circuit 8 and an increase in the size of the device.

SUMMARY OF THE INVENTION The present invention has been made in view of all of the above problems, and it is an object of the present invention to stably discharge an electrodeless discharge lamp and to reduce the size and efficiency of an apparatus. An object of the present invention is to provide an electrodeless discharge lamp lighting device.

[0018]

According to the first aspect of the present invention, there is provided an electrodeless discharge lamp in which a discharge gas is sealed in a bulb having a recess, and wherein the discharge lamp is disposed in the recess. An induction coil, a high-frequency power supply for supplying high-frequency power to the induction coil by receiving a supply from the DC power supply, a matching circuit for matching impedance of both the induction coil and the high-frequency power supply, A metal body having thermal conductivity, a voltage applied to the induction coil to generate a high-frequency electric field discharge in the induction coil, and a voltage applied to the induction coil to generate a high-frequency electromagnetic field discharge in the induction coil Switching means for switching between a voltage and a voltage is provided.

According to the second aspect of the present invention, a voltage applied to the induction coil for generating a high-frequency electric field discharge in the induction coil is applied to the induction coil for generating a high-frequency electromagnetic field discharge in the induction coil. The voltage is larger than the voltage.

According to the third aspect of the present invention, the time for applying a voltage to the induction coil to generate a high-frequency electric field discharge in the induction coil is longer than the time for applying a voltage to the induction coil to generate the high-frequency electromagnetic field discharge. Is also small.

According to the fourth aspect of the present invention, the high-frequency power supplied to the induction coil for generating the high-frequency electric field discharge in the induction coil is supplied to the induction coil for generating the high-frequency electromagnetic field discharge in the induction coil. It is characterized in that it is smaller than the high frequency power to be applied.

According to the invention described in claim 5, the switching means switches the impedance of the matching circuit.

According to a sixth aspect of the present invention, the switching means switches the oscillation frequency of the high-frequency power supply.

According to a seventh aspect of the present invention, the switching means switches the impedance of the induction coil.

According to an eighth aspect of the present invention, a dielectric is interposed between the metal body and the bulb.

According to the ninth aspect of the present invention, a capacitor is connected between the metal body and the low potential side of the induction coil.

According to a tenth aspect of the present invention, the capacitor connected between the metal body and the low potential side of the induction coil has a very small capacitance.

According to an eleventh aspect of the present invention, the shortest distance between the induction coil and the valve is extremely short.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to an electrodeless low-pressure discharge lamp L in which a metal cylindrical body 3 having an opening at the back of a hollow of a bulb 1 is inserted between the bulb 1 and an induction coil 2. The lighting circuit and the electrodeless discharge lamp are improved so as to prevent an increase in the size and efficiency of the device due to an increase in the voltage VE required for the lighting device.

First, the lighting circuit 8 will be described with reference to the circuit diagram shown in FIG. This circuit rectifies an AC power supply AC with a rectifier DB and converts a DC voltage smoothed by a smoothing capacitor C1 into switching elements Q1 and Q2 connected in series.
Is alternately turned on and off to convert the voltage into an AC high-frequency voltage, and through the inductor L1 and the capacitor C3, the capacitor C
By efficiently transmitting to the electrodeless low-pressure discharge lamp L by the matching circuit 6 composed of 4 to C7 and the switch element SW1, electromagnetic energy is given to the discharge gas sealed in the bulb 1 to excite it. The electrode low-pressure discharge lamp L is turned on. Further, the present circuit detects a high-frequency current flowing through the induction coil 2 by the detection circuit X via the current transformer CT, and controls the switching element SW1 in the matching circuit 6 by the switching circuit Y. Of the induction coil 2 is switched between a voltage VE for generating a high-frequency electric field discharge and a voltage VH for generating a high-frequency electromagnetic field discharge.
Is generated under optimum conditions.

The DC voltage smoothed by the capacitor C1 is used as a power source for the oscillation circuit and the drive circuit A via a series-parallel circuit composed of resistors R1 and R2 and a smoothing capacitor C2. The oscillating circuit and the driving circuit A cause the switching elements Q1, Q2 to oscillate at a high frequency via a transformer T1 having secondary windings n21, n22. The matching circuit 6 includes switching elements Q1, Q
Impedance matching between the inverter circuit including the inductor 2 and the induction coil 2 to eliminate reflection,
Alternatively, the high frequency power is supplied to the valve 1 efficiently.

Next, the operation of this circuit will be briefly described. Immediately after the AC power supply AC is turned on, the switching element SW1 is turned on to increase the Q of the matching circuit 6, apply the voltage VE to the induction coil 2, and generate a high-frequency electric field discharge in the bulb 1. After a certain period of time, or when valve 1
After the current transformer CT and the detection circuit X detect that the plasma state inside is a high-frequency electric field discharge, the switching element Y turns off the switch element SW1. When the switch element SW1 is turned off, the Q of the matching circuit 6 is lowered, the voltage VH is applied to the induction coil 2, a high-frequency electromagnetic field discharge is generated in the bulb 1, and the lamp is turned on.

As described above, since the Q of the matching circuit 6 can be switched by the switch element SW1, the electrodeless low-pressure discharge lamp L can be stably discharged with a simple configuration, and
The lighting circuit 8 can be prevented from increasing in size.

Instead of switching the Q of the matching circuit 6, the optimum voltage VE and the optimum voltage are determined by switching the oscillation frequency of the inverter circuit, switching the impedance of the induction coil 2, and further combining these switchings. It may be configured to generate VH.

Next, the electrodeless low-pressure discharge lamp L will be described with reference to a partially cutaway front view shown in FIG.

The difference from the second conventional example shown in FIG. 5 lies in that a dielectric 20 having a high dielectric constant is interposed between the metal cylindrical body 3 and the inner wall of the bulb 1, and the other first embodiment is different from the second prior art. 2 The same components as those of the conventional example are denoted by the same reference numerals, and description thereof is omitted. The dielectric 20 may be installed only near the top of the metal tubular body 3, that is, only near the deepest part of the hollow of the bulb 1.

The dielectric 20 lowers the dielectric constant between the induction coil 2 and the inner wall of the bulb 1 and lowers the voltage VE for generating a high-frequency electric field discharge. Thus, the lighting circuit 8 can be further reduced in size.

If a metal plate having the same potential as the ground side of the lighting circuit 8 is inserted between the induction coil 2 and the bulb 1 containing the discharge plasma, it is difficult to shift to the high-frequency electric field discharge. As shown in the cutaway front view, after electrically insulating the metal cylinder 3, the metal cylinder 3 and the low potential side 2 b of the induction coil 2 are connected by a capacitor Co having a small capacitance. , The induction coil 2 through the inner wall of the valve 1
Since the stray capacitance Cx between the top of the metal cylinder and the metal cylinder 3 increases, or since the metal cylinder 3 has a small potential via the capacitor Co, a high-frequency electric field discharge is likely to occur. . Further, the high-frequency electric field is shielded by the metal tubular body 3, the high-frequency electromagnetic field which causes the blackening of the phosphor 9 in the bulb 1 is suppressed, and the lamp life can be extended.

The valve shown in FIG. 3 has a protrusion k at the deepest portion of the hollow of the bulb 1, and the induction coil 2 approaches or comes into contact with the protrusion k so that the discharge space of the protrusion k is formed. First, a high-frequency electric field discharge is generated, and thereafter, a high-frequency electromagnetic field discharge is generated.
As described above, the metal tubular body 3 is not interposed between the induction coil 2 and the protruding portion k of the valve 1.
And the distance between the protrusion k of the valve 1 is very short,
High frequency electromagnetic field discharge is likely to occur.

[0040]

According to the first to seventh aspects of the present invention, there is provided an electrodeless discharge lamp lighting device capable of stably discharging an electrodeless discharge lamp and capable of reducing the size and efficiency of the device. Can be provided.

According to the eighth aspect of the present invention, the dielectric constant between the induction coil and the bulb is reduced, and the voltage for generating the high-frequency electric field discharge can be reduced. It is possible to provide an electrodeless discharge lamp lighting device capable of discharging and capable of reducing the size and efficiency of the device.

According to the ninth and tenth aspects of the present invention, the stray capacitance between the induction coil and the metal body increases through the inner wall of the valve, or the metal body passes through the capacitor. A high-frequency electric field discharge, which makes it easier to generate a stable discharge of the electrodeless discharge lamp, and provides an electrodeless discharge lamp lighting device capable of reducing the size and increasing the efficiency of the device. it can.

According to the eleventh aspect of the present invention, since the distance between the induction coil and the bulb is extremely short, high-frequency electromagnetic field discharge is easily generated, and further stable discharge of the electrodeless discharge lamp is possible. In addition, it is possible to provide an electrodeless discharge lamp lighting device capable of reducing the size and increasing the efficiency of the device.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of an embodiment according to the present invention.

FIG. 2 is a partially cutaway front view of the embodiment according to the present invention.

FIG. 3 is another partially cutaway front view of the embodiment according to the present invention.

FIG. 4 is a partially cutaway front view of the first conventional example according to the present invention.

FIG. 5 is a partially cutaway front view of a second conventional example according to the present invention.

FIG. 6 is a characteristic diagram showing a change in an induction coil voltage from starting to lighting of an electrodeless discharge lamp according to the present invention.

FIG. 7 is another characteristic diagram showing a change in the induction coil voltage from start to lighting of the electrodeless discharge lamp according to the present invention.

[Explanation of symbols]

 Reference Signs List 1 bulb 2 induction coil 3 metal body 6 matching circuit 20 dielectric C capacitor L electrodeless discharge lamp V voltage

Claims (11)

[Claims] 1. An electrodeless discharge lamp in which a discharge gas is sealed in a bulb having a depression, an induction coil disposed in the depression, and a high-frequency power supplied to the induction coil by being supplied from a DC power supply. An electrodeless discharge lamp lighting device comprising: a high-frequency power supply, a matching circuit that performs impedance matching for both the induction coil and the high-frequency power supply, and a metal body that is disposed in the recess and has good thermal conductivity. Here, a voltage applied to the induction coil for generating a high-frequency electric field discharge in the induction coil and a voltage applied to the induction coil for generating a high-frequency electromagnetic field discharge in the induction coil are switched. A lighting device for an electrodeless discharge lamp, comprising switching means. 2. A voltage applied to the induction coil to generate a high-frequency electric field discharge in the induction coil is lower than a voltage applied to the induction coil to generate a high-frequency electromagnetic field discharge in the induction coil. 2. The electrodeless discharge lamp lighting device according to claim 1, which is large. 3. A time for applying a voltage to the induction coil to generate a high-frequency electric field discharge in the induction coil is shorter than a time for applying a voltage to the induction coil to generate a high-frequency electromagnetic field discharge. Claim 2
The electrodeless discharge lamp lighting device as described in the above. 4. The high-frequency power supplied to the induction coil for generating a high-frequency electric field discharge in the induction coil is the high-frequency power supplied to the induction coil for generating a high-frequency electromagnetic field discharge in the induction coil. The electrodeless discharge lamp lighting device according to any one of claims 1 to 3, wherein the lighting device is smaller than the discharge lamp. 5. The electrodeless discharge lamp lighting device according to claim 1, wherein the switching unit switches the impedance of the matching circuit. 6. The electrodeless discharge lamp lighting device according to claim 1, wherein the switching unit switches an oscillation frequency of the high-frequency power supply. 7. The electrodeless discharge lamp lighting device according to claim 1, wherein the switching unit switches the impedance of the induction coil. 8. The electrodeless discharge lamp lighting device according to claim 1, wherein a dielectric is interposed between said metal body and said bulb. 9. An electrodeless discharge lamp lighting device according to claim 1, wherein a capacitor is connected between said metal body and a low potential side of said induction coil. 10. The electrodeless discharge lamp lighting device according to claim 9, wherein the capacitor has a very small capacity. 11. The lighting device for an electrodeless discharge lamp according to claim 1, wherein a shortest distance between the induction coil and the bulb is extremely short.