JPH0745250A - Solenoid field type discharge lamp - Google Patents

Abstract

PURPOSE:To provide a solenoid field type discharge lamp for preventing damage of a partition between a starting fine tube and a bulb. CONSTITUTION:A high frequency exciting coil 20 is arranged by surrounding a bulb 10 sealed with a luminous substance, to connect a starting fine tube 15 isolated from the bulb, and in this starting fine tube, a starting discharge is generated by starting gas, to induce a plasma discharge in the bulb by this starting discharge, so that the luminous substance is made to emit light. In this solenoid field type discharge lamp, in the case of assuming s0 for internal sectional area of the starting fine tube and s1 for area of a partition between this fine tube and the bulb inside, a relation where 1.1<=s1/S0<=9 is set. Since the area s1 of the partition is set larger than the internal sectional area s0 of the starting fine tube, current density of the partition can be decreased, and a temperature rise of the partition can be suppressed, to prevent its damage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solenoid magnetic field type discharge lamp in which a plasma discharge is generated in a bulb by a high frequency excitation coil, and a luminescent material in the bulb is caused to emit light by this discharge.

[0002]

2. Description of the Related Art In a well-known high pressure metal vapor discharge lamp, that is, an HID discharge lamp, electrodes made of a refractory metal structure are sealed at both ends of an arc tube, and arc discharge is generated between these electrodes. The luminescent metal generated and sealed in the bulb is ionized and excited to emit light. However, in the lamp having such a structure, since the electrodes are arranged in the bulb, the sealing structure of the electrodes becomes complicated, and special measures are required to prevent leakage from the electrode sealing part. Is exposed to the discharge space, which causes various problems such as erosion of the electrodes.

Solenoid magnetic field type discharge lamps are attracting attention as lamps for solving the above-mentioned problems with electrode-type discharge lamps. In the solenoid magnetic field type discharge lamp, as shown in FIG. 7, a light emitting substance is enclosed in a transparent bulb 10, and a high frequency excitation coil 20 is arranged so as to surround the bulb 10. The excitation coil 20 is a matching box 25. It is connected to the high frequency oscillation circuit 26 via. When a high-frequency current is passed from the high-frequency oscillator circuit 26 to the excitation coil 20, a high-frequency magnetic field is generated, which causes a ring-shaped plasma discharge 12 in the bulb 10 to cause the luminescent substance to emit light.

Since such a lamp has no electrode in the bulb 10, it is also called an electrodeless discharge lamp, and it is possible to solve the problem of the electrode type lamp. By the way, in this type of solenoid magnetic field type discharge lamp, in order to generate plasma discharge in the bulb 10, it is necessary to create a very high electric field gradient in the bulb 10 to cause discharge.

In the prior art, for example, Japanese Patent Laid-Open No. 26004/1990.
Japanese Patent Publication No. 8 discloses a starting means in this type of solenoid magnetic field type discharge lamp. That is, the starting means described in this publication has starting electrodes provided at both ends of the valve, and a starting voltage is applied between the starting electrodes to cause discharge breakdown in the valve, thereby starting the device. It is the one.

However, since such a structure in which a starting electrode is provided is originally developed as an electrodeless discharge lamp of this type of solenoid magnetic field type discharge lamp, the purpose is to provide no electrode. Although it is for start-up, the installation of electrodes is against the purpose thereof, and the sealing and arrangement structure of the electrodes becomes complicated, causing problems such as erosion of the electrodes.

From the above, the starting means shown in FIG.
There has been proposed a structure in which a starting thin tube (also referred to as a gas probe) as shown in FIG. This is a valve 10
On one side, it is desirable that the same material as the valve is used for the thin tube 1.
5 are connected. The thin tube 15 is isolated from the inside of the valve 10 via a partition wall 16.
At least one of argon and krypton, for example, is enclosed as a starting rare gas. A starting electrode 17 is attached to the thin tube 15, and the starting electrode 17 includes capacitors 18a, 18a 'and an impedance 18b.
Is connected to a starting circuit 18 including
8 is connected to a high frequency oscillation circuit 26 via a matching box 25. The excitation coil 20 is connected to the high frequency oscillation circuit 26 via the matching box 25.

In such a structure, when a high frequency voltage is applied to the starting electrode 17, a potential difference is generated between the starting electrode 17 and the high frequency electric field generated in the valve 10 by the high frequency magnetic field of the excitation coil 20. It is generated, which causes glow discharge due to the starting rare gas in the thin tube 15. This glow discharge generates an electric field gradient between the inside of the bulb 10 and, therefore, plasma discharge is induced inside the bulb 10 and a ring-shaped discharge 12 is generated.

[0009]

However, in the case of the starting means using the starting thin tube 15 as described above, if the glow discharge is continued in the thin tube 15 at the time of starting, the partition 16 may be damaged. That is, when a glow discharge is generated in the thin tube 15 and an electric field gradient is generated between the thin tube 15 and the inside of the bulb 10, the electric field is concentrated on the partition 16 and the temperature of the partition 16 rises. If such a glow discharge state is continued, the electric resistance of the glass partition 16 becomes low, current concentrates, and it concentrates more and more particularly on the spot of high temperature, and the temperature further rises. Since the gas pressures in the thin tube 15 and the valve 10 are different, when the partition wall 16 is softened due to the temperature rise, blow-through occurs, which may cause the thin tube 15 to lose its function.

The present invention has been made in view of the above circumstances, and it is possible to prevent the partition between the starting thin tube and the valve from being damaged and to maintain the function of the starting thin tube for a long period of time. It is intended to provide a solenoid magnetic field type discharge lamp.

[0011]

According to the first aspect of the present invention, a luminescent substance is enclosed in a light-transmitting bulb, and a high-frequency excitation coil is arranged so as to surround the bulb. Isolate and connect the starting thin tube,
A starting rare gas is sealed in the starting thin tube, a starting discharge is generated by the starting gas in the narrow tube, a plasma discharge is induced in the bulb by the starting discharge, and the light emission is caused by the plasma discharge in the bulb. In a solenoid magnetic field type discharge lamp that emits light from a substance, if the inner cross-sectional area of the starting thin tube is s ₀ and the area of the partition wall separating the thin tube and the valve is s ₁ , 1.1 ≦ s ₁ It is characterized in that / s ₀ ≦ 9.

A second aspect of the present invention is to enclose a luminescent material in a light-transmitting bulb and to dispose a high-frequency excitation coil around the bulb so that the bulb is isolated from the bulb for starting. A thin tube is connected, a starting rare gas is sealed in this starting thin tube, and a starting discharge is generated by the starting gas in this thin tube, and a plasma discharge is induced in this valve by this starting discharge. In a solenoid magnetic field type discharge lamp in which the light emitting substance is caused to emit light by plasma discharge, an average wall thickness of the bulb is t ₀ ,
The thickness of the partition wall separating the starting thin tube and the valve is t
_When it is set to ₁ , 1.1 ≦ t ₁ / t ₀ ≦ 4 is characterized.

[0013]

According to the first aspect of the present invention, since the area s ₁ of the partition wall is made larger than the internal cross-sectional area s ₀ of the starting thin tube, the current density of the partition wall can be reduced, and therefore the temperature rise of the partition wall can be increased. It can be suppressed and the partition wall can be prevented from being damaged. However, when the area ratio s ₁ / s ₀ exceeds 9, the electric field spreads too much and a strong electric field is not induced in the arc tube.
It becomes difficult to generate arc discharge.

Further, according to the second aspect of the present invention, since the wall thickness t _{1 of the} partition wall is made larger than the average wall thickness of other portions of the valve to t ₀ , the heat capacity is increased and the temperature rise of the partition wall is suppressed. It is possible to prevent the partition walls from being damaged. However, when the wall thickness ratio t ₁ / t ₀ exceeds 4, the resistance of the partition wall increases and the voltage drop increases, a strong electric field is not induced in the arc tube, and it becomes difficult to generate arc discharge.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the first embodiment shown in FIGS. 1 shows a solenoid magnetic field type discharge lamp, which is connected to a power supply circuit similar to the high frequency power supply circuit shown in FIG. 7, so the high frequency power supply circuit is not shown in FIG. However, in FIG. 7, 30 is a switch, and this switch 30 is provided between the starting circuit 18 and the matching box 25. The switch 30 is adapted to be turned on / off by a signal from the optical sensor 31, and when the optical sensor 31 detects the light emitting state of the bulb 10, the switch 30 is turned off and the starting circuit 18 is opened. It is designed to keep

The arc tube bulb 10 shown in FIG. 1 is made of, for example, a high melting point glass such as synthetic quartz or a transparent ceramic material such as alumina. When used as a light-emitting substance that emits light by the electric discharge 12, for example, as a light source for ultraviolet irradiation, an iron halide, for example, iron iodide is enclosed. In addition to the light emitting substance, at least one rare gas such as argon, xenon, krypton, or neon is enclosed in the bulb 10.

An excitation coil 20 is arranged around the valve 10. The excitation coil 20 is made of a highly conductive metal such as high-purity aluminum or copper, or silver, and the coil wire has a non-circular cross-sectional shape, for example, a flat shape. Both ends of the excitation coil 20 are connected to a high frequency power supply circuit similar to that shown in FIG.

When a high-frequency current is passed through the exciting coil 20, a magnetic field is generated in the exciting coil 20 along the coil axis direction O--O of the exciting coil 20, whereby the central portion of the coil 20 is accommodated. In the valve 10, the coil axis O-
A donut-shaped arc created by plasma surrounding O.
A black discharge 12 is generated. The discharge metal 12 ionizes and excites the luminescent metal to emit ultraviolet rays, and the ultraviolet rays pass through the bulb 10 and are emitted to the outside.

A starting thin tube 15 is connected to one end of the valve 10, for example, located on the center line. Thin tube 1
5 is preferably the same material as the valve, valve 1
It is isolated from the inside of 0 through a partition wall 16. Further, at least one kind of argon or krypton is enclosed in the thin tube 15 as a rare gas for starting.

A starting electrode 17 is attached to the thin tube 15, and the starting electrode 17 is connected to the starting circuit shown in FIG. A starting voltage is supplied to the starting electrode 17,
At the same time, when a high frequency current is passed through the excitation coil 20 to generate an electric field due to the high frequency magnetic field in the bulb 10, a potential difference is generated between the starting electrode 17 and the electric field of the bulb 10, and the rare gas in the thin tube 15 is glow-discharged. To occur. An electric field gradient is generated between the glow discharge and the electric field in the bulb 10, so that plasma discharge is induced in the bulb 10 and thus a ring-shaped discharge 12 is generated.

By the way, in the case of the present embodiment, the starting thin tube 1
5 has a root formed to have a large diameter and is joined to the valve 10. Therefore, the cross-sectional area of the starting thin tube 15 is s ₀ , and the area of the partition wall 16 separating the thin tube 15 and the inside of the valve 10 is s. _When it is set to ₁ , the area s _{1 of the} partition wall 16 is formed larger than the inner cross-sectional area s ₀ of the thin tube 15, and the area ratio in this case is set in the range of 1.1 ≦ s ₁ / s ₀ ≦ 9. ing.

In such a structure, since the area s _{1 of the} partition wall 16 is made larger than the internal cross-sectional area s ₀ of the starting thin tube 15, it is possible to prevent blowout damage of the partition wall 16 at the time of starting. That is, at the time of starting, the rare gas in the thin tube 15 generates glow discharge, and an electric field gradient is generated between this glow discharge and the electric field in the valve 10, which induces plasma discharge in the valve 10. But
Since the area s _{1 of the} partition wall 16 is increased, local concentration of current on the partition wall 16 is eliminated, and the current density can be reduced, so that the temperature rise of the partition wall 16 can be suppressed. As a result, damage such as the high-pressure gas in the valve 10 blowing through the low-pressure side thin tube 15 is prevented.

When the area ratio s ₁ / s ₀ exceeds 9, the electric field spreads too much, the current density of the partition wall 16 becomes too small, and a strong electric field cannot be induced in the valve 10.
It takes time to start and it becomes difficult to generate arc discharge.

Such numerical characteristics have been confirmed by the experiments of the present inventors. That is, mercury and 200 Torr argon gas were enclosed in a bulb 10 having an inner diameter of 40 mm to manufacture a solenoid magnetic field type discharge lamp with a rated input of 240 W. The starting thin tube 15 has an inner diameter of 2 mm (cross-sectional area s ₀ =
0.0314cm ² ), height is 60mm, 4 inside
It is filled with 0 Torr of argon gas.

Such a lamp was connected to the high frequency power supply circuit shown in FIG. 7 and a high frequency of 13.56 MHz was applied. A current of 1 A was applied to the starting electrode 17 at a voltage of 300 V, and at the same time, an electric power of 200 W was supplied to the excitation coil 20.

When the area s ₁ of the partition 16 was variously changed in such a state, the time when the partition was damaged and the time required for lighting were measured. FIG. 2 shows the area ratio s ₁ / s
It is a graph which shows the relationship between ₀ and the time until a partition is damaged. From this characteristic, if s ₁ / s ₀ is 1 or more,
That is, it was confirmed that if the area s _{1 of the} partition wall 16 is made larger than the internal cross-sectional area s ₀ of the starting thin tube 15, it is possible to extend the time until the partition wall 16 is damaged. Considering this, the area ratio s ₁ / s ₀ is 1.
It is desirable to set it to 1 or more.

FIG. 3 is a graph showing the relationship between the area ratio s ₁ / s ₀ and the time required for lighting. From this characteristic, it has been confirmed that when s ₁ / s ₀ exceeds 9, the time required for starting becomes long and the practical limit is reached.

By such an experiment, the area s of the partition 16 is
₁ and the inner cross-sectional area s ₀ of the thin tube 15, that is, the area ratio s ₁
/ S ₀ is preferably in the range of 1.1 to 9. Next, the second invention will be described based on FIGS. 4 to 6. FIG. 4 shows a discharge lamp according to another embodiment, in which the wall thickness t ₁ of the partition wall 16 is made larger than the average wall thickness t ₀ of other portions of the bulb 10. Actually, the wall thickness ratios thereof are set in the range of 1.1 ≦ t ₁ / t ₀ ≦ 4.

In such a structure, since the wall thickness t ₁ of the partition wall 16 is made larger than the wall thickness t ₀ of the valve 10,
Since the heat capacity of the partition 16 is increased and heat diffusion is promoted, the temperature rise of the partition can be suppressed. As a result,
This prevents damage such as the high-pressure gas inside the valve 10 blowing through the thin tube 15 on the low-pressure side.

When the wall thickness ratio t ₁ / t ₀ exceeds 4,
The electric resistance of the partition wall 16 increases, causing a voltage drop, and a strong electric field cannot be induced in the bulb 10 due to glow discharge generated in the starting thin tube 15, and it takes a long time to start or arc discharge occurs. Becomes difficult.

The inventors have also confirmed the above numerical characteristics by experiments. That is, the average wall thickness t _{0 is set} to 0.9 mm, and the other conditions are the same as those of the discharge lamp shown in FIG.
(With 00 Torr argon gas enclosed), an inner diameter of 4 m
A thin tube 15 of m and 60 mm in height was connected, and 40 Torr of argon gas was sealed inside. This lamp was connected to the high frequency power supply circuit shown in FIG. 7, and a high frequency of 13.56 MHz was applied. A current of 1 A was applied to the starting electrode 17 at a voltage of 300 V, and at the same time, an electric power of 200 W was supplied to the excitation coil 20.

When the wall thickness t ₁ of the partition 16 was changed variously in such a state, the time for the partition to break and the time required for lighting were measured. FIG. 5 shows the thickness ratio t ₁ / t
It is a graph which shows the relationship between ₀ and the time until a partition is damaged. From this characteristic, if t ₁ / t _{0 is set} to 1 or more,
That is, it was confirmed that if the wall thickness t ₁ of the partition wall 16 is made larger than the average wall thickness t ₀ of the other portion of the valve 10, the time until the partition wall 16 is damaged can be extended. Considering the molding error, the wall thickness ratio t ₁ / t ₀ is preferably 1.1 or more.

FIG. 6 is a graph showing the relationship between the wall thickness ratio t ₁ / t ₀ and the time required for lighting. From this characteristic, it was confirmed that when t ₁ / t ₀ exceeds 4, the time required for starting becomes long and the practical limit is reached.

According to such an experiment, the wall thickness t of the partition wall 16 is
The ratio of ₁ to the average wall thickness t ₀ of the valve is desired to be in the range of 1.1 to 4. In each embodiment, since the excitation coil 20 has a flat cross-sectional shape, the surface area is increased, and since the high frequency current has the property of flowing on the surface of the conductor, the skin effect is increased and the resistance to the current is decreased.
Further, since the surface area is large, the heat dissipation effect is increased, and in combination with the decrease in the resistance, self-heating is reduced, and the coil efficiency is improved. However, the present invention is not limited to the shape of the coil, and the coil may be formed by a wire having a circular cross section.

[0035]

As described above, according to the first aspect of the present invention, since the partition wall area s ₁ is larger than the internal cross-sectional area s ₀ of the starting thin tube, the partition wall current density can be reduced. Therefore, the temperature rise of the partition wall can be suppressed,
It is possible to prevent the partition wall from being damaged. Moreover, the area ratio s
_{Since 1} / s ₀ is limited to less than 9, it is possible to prevent the electric field from spreading too much and to induce a strong electric field in the arc tube, which facilitates the occurrence of arc discharge.

Further, according to the second invention, since the thickness t ₁ of the partition wall average thickness of the other parts of the valve is made larger than t _0, the heat capacity is increased to suppress the temperature rise in the partition wall It is possible to prevent the partition walls from being damaged. Also in this case, since the wall thickness ratio t ₁ / t ₀ is limited to less than 4, the voltage drop of the partition wall does not increase, the occurrence of arc discharge is promoted, and good startability can be maintained.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a solenoid magnetic field type discharge lamp showing a first embodiment of the present invention.

FIG. 2 is a characteristic diagram showing a relationship between an area ratio and a time until a partition wall is broken in the example.

FIG. 3 is a characteristic diagram showing the relationship between the area ratio and the time required for lighting in the example.

FIG. 4 is a configuration diagram of a solenoid magnetic field type discharge lamp showing a second embodiment of the present invention.

FIG. 5 is a characteristic diagram showing a relationship between a wall thickness ratio and a time until a partition wall is broken in the example.

FIG. 6 is a characteristic diagram showing a relationship between a wall thickness ratio and a time required for lighting in the example.

FIG. 7 is a configuration diagram showing a solenoid magnetic field type discharge lamp and a lighting circuit therefor showing a background art of the present invention.

[Explanation of symbols]

10 ... Bulb, 12 ... Arc discharge, 15 ... Capillary for starting,
16 ... Partition wall, 17 ... Starting electrode.

Claims (2)

[Claims] 1. A light-emitting substance is enclosed in a translucent bulb, a high-frequency excitation coil is arranged so as to surround the bulb, and a starting thin tube is connected to the bulb so as to be isolated from the interior of the bulb. A starting rare gas is sealed in the starting thin tube, a starting discharge is generated by the starting gas in the narrow tube, a plasma discharge is induced in the bulb by the starting discharge, and the light emission is caused by the plasma discharge in the bulb. In a solenoid magnetic field type discharge lamp that emits light from a substance, if the inner cross-sectional area of the starting thin tube is s ₀ and the area of the partition wall separating the thin tube and the valve is s ₁ , 1.1 ≦ s ₁ / S ₀ ≤9 Solenoid magnetic field type discharge lamp. 2. A light-emitting substance is enclosed in a translucent bulb, a high-frequency excitation coil is arranged so as to surround the bulb, and a starting thin tube is connected to the bulb so as to be isolated from the interior of the bulb. A starting rare gas is sealed in the starting thin tube, a starting discharge is generated by the starting gas in the narrow tube, a plasma discharge is induced in the bulb by the starting discharge, and the light emission is caused by the plasma discharge in the bulb. In a solenoid magnetic field type discharge lamp adapted to emit a substance, when the average wall thickness of the bulb is t ₀ and the partition wall separating the starting thin tube and the bulb is t ₁ , 1.1 ≦ A solenoid magnetic field type discharge lamp characterized in that t ₁ / t ₀ ≦ 4.