JP3069432B2 - Electrodeless discharge lamp - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrodeless electrode in which a discharge gas is excited and emits light by applying a high-frequency electromagnetic field to the discharge gas inside the bulb from outside the bulb without having an electrode inside the bulb. It relates to a discharge lamp.

[0002]

2. Description of the Related Art Conventionally, this kind of electrodeless discharge lamp has features such as small size, high output, and long life, and has been researched and developed in various places. The use to is considered. As an electrodeless discharge lamp, as shown in FIG. 3, a discharge gas in which a rare gas and a luminescent substance are mixed is sealed in a bulb 1 formed of a translucent material such as quartz glass and guided around the bulb 1. A coil 2 is provided. A high-frequency current is supplied to the induction coil 2 from a high-frequency power supply 4. Further, the two starting aid electrodes 3a crosspiece 3 ₁ formed in a substantially T-shaped is arranged along the winding direction of the winding of the induction coil 2 with the conductive plate on the outer peripheral wall of the valve 1 (for example, a copper plate) comprises 3b, valve 1 crosspiece 3 ₁ in the form of arranging in the circumferential direction of the valve 1
It is arranged close to. Both starting aid electrodes 3a, distance crosspiece 3 ₁ of 3b is set relatively narrow. The starting aid electrode 3a, the 3b high-frequency voltage is applied by the high-frequency power supply 5 connected to the vertical piece 3 _2.

At the time of starting, a high frequency voltage is first applied to the starting auxiliary electrodes 3a and 3b by a high frequency power supply 5. At this time, a high-frequency electric field is generated around the starting auxiliary electrodes 3a and 3b, and the starting auxiliary electrodes 3a and 3b are electrostatically coupled to the internal space of the bulb 1.
Electrons near a and 3b collide with the atoms of the discharge gas to ionize the atoms of the discharge gas. When sufficient phenomena are supplied to maintain the discharge by repeating such a phenomenon, a streamer-like preliminary discharge is generated along the starting auxiliary electrodes 3a and 3b. When a high-frequency current is supplied from the high-frequency power supply 4 to the induction coil 2 in a state where the preliminary discharge has occurred, a high-frequency magnetic field interlinking the induction coil is generated, and a toroidal induction electric field interlinking the high-frequency magnetic field is generated. . The high-frequency magnetic field generated by the induction coil 2 links with the preliminary discharge. Therefore, the preliminary discharge is induced and extended along the induced electric field, and when the preliminary discharge finally becomes one, a main discharge having a toroidal discharge path (generally called an annular discharge or a high-frequency ring discharge) (Discharge state in which the discharge gas is discharged), and strong light emission is generated by the excitation of the discharge gas to be turned on. Here, since the induction coil 2 generates the induction electric field in the same direction as the preliminary discharge, energy for changing the direction of the discharge path at the transition from the preliminary discharge to the main discharge is not required. When the state shifts to the lighting state, the lighting state is maintained without applying a high-frequency voltage to the starting auxiliary electrodes 3a and 3b.

[0004]

By the way, when a discharge gas containing mercury as a luminescent substance is used as the discharge gas, the initial start-up becomes relatively easy, but it is difficult to restart immediately after the light is turned off. There is. Further, since the vapor pressure of mercury changes exponentially with an increase in temperature, it is difficult to match with a high-frequency power supply for supplying a high-frequency current to the induction coil 2. And it cannot be stably lit. On the other hand, if the discharge gas does not contain mercury, the alignment becomes easier, but the initial startup becomes very difficult. If a high voltage is applied to the induction coil, it is possible to forcibly start the induction coil. However, a high-frequency power supply capable of outputting a high voltage is required, which causes a problem that the high-frequency power supply as a lighting circuit becomes large.

In order to solve such a problem, it is conceivable to increase the electric field strength between the starting auxiliary electrodes 3a and 3b so that the preliminary discharge is easily generated. That is,
It is necessary to reduce the distance between the starting auxiliary electrodes 3a and 3b. However, if the gap between the starting auxiliary electrodes 3a, 3b is reduced, a discharge occurs outside the bulb 1 between the starting auxiliary electrodes 3a, 3b before the preliminary discharge occurs inside the bulb 1, and the starting auxiliary electrode 3a, 3b is discharged. There is a problem that 3a and 3b are damaged.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to provide an electrodeless discharge lamp which does not need to supply a large electric power to a starting auxiliary electrode and has a good startability.

[0007]

According to the present invention, in order to achieve the above object, a high-frequency current is supplied from a high-frequency power supply 4 to an induction coil 2 having a winding wound around the outer periphery of a bulb 1 made of a translucent material. In a non-electrode discharge lamp that excites and emits a discharge gas by applying a high-frequency electromagnetic field formed inside a radial winding of the induction coil 2 to a discharge gas sealed in the bulb 1, A plurality of starting auxiliary electrodes 3 arranged near the outer wall surface of the bulb 1 so as to be electrostatically coupled to the internal space of the valve 1 and to which a high-frequency voltage is applied
a, 3b are provided, and a convex portion 1a bulging outward is formed at a key portion of the peripheral wall of the bulb 1 and each starting auxiliary electrode 3a,
3b is disposed at a position where it is electrostatically coupled to the internal space of the projection 1a.

[0008]

According to the first aspect of the present invention, when a high-frequency current is applied to the induction coil, a high-frequency magnetic field formed around the induction coil acts on the discharge gas sealed in the bulb to cause the discharge of the high-frequency magnetic field. A toroidal induced electric field is generated in 1
This induction electric field causes a main discharge having a toroidal discharge path to be turned on. Here, prior to energizing the induction coil 2 with a high-frequency current, the starting auxiliary electrodes 3a, 3
When a high-frequency voltage is applied to the valve b, a streamer-like preliminary discharge is generated in the bulb along the starting auxiliary electrodes 3a and 3b. Also, by forming a convex portion 1a bulging outward on the bulb 1, and arranging a part of each of the starting auxiliary electrodes 3a, 3b at a position where it is electrostatically coupled to the internal space of the convex portion 1a, the starting is achieved. The distance between the auxiliary electrodes 3a and 3b can be reduced in the vicinity of the convex portion 1a, and the strong electric field generated around the starting auxiliary electrodes 3a and 3b near the convex portion 1a acts on the discharge gas inside the convex portion 1a. To facilitate the generation of electrons. In short, a high-frequency electric field is intensively formed in a narrow space in the convex portion 1a to provide an environment in which dielectric breakdown easily occurs in the discharge gas, thereby facilitating the generation of the preliminary discharge. As a result, a preliminary discharge can be easily generated without generating a discharge outside the bulb 1. As a result of the predischarge being more likely to occur as described above, the supply energy at the time of starting is reduced, and the power supply can be reduced in size, and the overall size can be reduced.

[0009]

(Embodiment 1) As shown in FIG. 1, a bulb 1 is formed in a hermetically spherical shape by using a translucent material such as quartz glass. 1a is formed. Xenon gas of, for example, 100 Torr is sealed in the bulb 1 as a discharge gas. The winding of the induction coil 2 is wound around the outer periphery of the valve 1 so as to have a center line in the projecting direction of the projection 1a (see FIG. 3). The induction coil 2 is wound, for example, three turns. On the outer peripheral wall of the bulb 1, two substantially T-shaped auxiliary starting electrodes 3a and 3b made of a conductive plate (for example, a copper plate) are arranged in close contact. Crosspiece 3 ₁ T shaped plan and the valve 1 perpendicular to the center line of the convex portion 1a
Are arranged on the ring is a line of intersection between the outer peripheral wall of the vertical piece 3 ₂ of the T-shaped is extended to both sides of the projecting portion 1a along the outer peripheral wall of the valve 1. Accordingly, the convex portion 1a will be both starting auxiliary electrode 3a, it is sandwiched between the longitudinal pieces 3 ₂ 3b. Here, both the starting auxiliary electrode 3a sandwiching the convex portion 1a, the vertical piece 3 ₂ interval 3b, starting auxiliary electrode 3a, the discharge outside the valve 1 upon application of the high frequency voltage by the high-frequency power supply 5 between 3b Is set to a size that does not occur.

An induction coil 2 is supplied with a high-frequency current from a high-frequency power supply 4 to generate a high-frequency magnetic field. The high-frequency magnetic field acts on a discharge gas inside the bulb 1 to generate a main discharge having a toroidal discharge path. The discharge gas is excited to emit light. That is, a toroidal induced electric field is generated in the bulb 1 along the winding direction of the winding of the induction coil 2 by the high frequency magnetic field, and a discharge plasma is generated in the bulb 1 by the induced electric field. Main discharge is maintained. The high frequency power supply 4 includes a high frequency generator for generating a high frequency, an amplifier for amplifying the output of the high frequency generator, and a matching circuit inserted between the amplifier and the induction coil 2 for matching the impedance.

A high-frequency voltage is applied between the starting auxiliary electrodes 3a and 3b by a high-frequency power supply 5 to generate a streamer-like preliminary discharge in the bulb 1. That is, when a high-frequency voltage is applied between the starting auxiliary electrodes 3a and 3b to form a high-frequency electric field, the starting auxiliary electrodes 3a and 3b
The electrons in the vicinity of 3b collide with the xenon atoms to ionize the xenon atoms. When such a phenomenon is repeated and sufficient electrons are supplied to maintain the discharge, the starting auxiliary electrodes 3a, A streamer-like preliminary discharge is generated along 3b. Here, the high-frequency power supply 5 includes a matching circuit and the like similarly to the high-frequency power supply 4.

At the time of starting, a high-frequency voltage is first applied to the starting auxiliary electrodes 3a and 3b by the high-frequency power supply 5. At this time, both starting auxiliary electrodes 3a,
Because the vertical piece 3 ₂ 3b are closer distance than the other portions, the electric field formed around the starting aid electrodes 3a, 3b is stronger than the other portions in the vicinity of the projecting portion 1a. Further, since the vertical piece 3 ₂ are disposed to sandwich the projecting portion 1a, starting auxiliary electrode 3
a and 3b are electrostatically coupled to the discharge gas to promote ionization of the discharge gas. In other words, since a minute discharge is generated in a narrow space in the convex portion 1a to generate electrons, a preliminary high-frequency electric field generated around both of the starting auxiliary electrodes 3a and 3b causes the auxiliary to be along the starting auxiliary electrodes 3a and 3b. Discharge occurs easily. When a high-frequency current is supplied from the high-frequency power supply 4 to the induction coil 2 in a state where the preliminary discharge has occurred, a high-frequency magnetic field interlinking the induction coil is generated, and an induction electric field interlinking the high-frequency magnetic field is generated. The high-frequency magnetic field generated by the induction coil 2 links with the preliminary discharge. As described above, the induction electric field acts on the preliminary discharge to shift to the main discharge, and a strong light emission is generated by the excitation of the discharge gas to be turned on. Here, since the induction coil 2 generates an induction electric field in the same direction as the preliminary discharge, energy for changing the direction of the discharge path at the transition from the preliminary discharge to the main discharge is unnecessary. When the state shifts to the lighting state, the lighting state is maintained without applying a high-frequency voltage to the starting auxiliary electrodes 3a and 3b.

By providing the starting auxiliary electrodes 3a and 3b as described above, the initial input for forming the main discharge can be greatly reduced. As a result, the power supply can be reduced in size and can be easily started. Here, as the discharge gas, other single gas or mixed gas may be used instead of xenon gas, and the gas pressure is not limited to 100 Torr. Valve 1
Various shapes can be adopted in addition to the spherical shape. Further, the number of turns of the induction coil 2 and the shapes of the starting auxiliary electrodes 3a and 3b are not limited to those described above.

Embodiment 2 In this embodiment, a discharge gas in which a metal or a metal halide is mixed with xenon gas is used. In this case, the vapor pressure of the metal or the metal halide depends on the temperature of the coldest point. The main discharge has a toroidal discharge path along the winding direction of the winding of the induction coil 2, and the discharge gas is sealed in the bulb 1. The coldest point will be formed at the bottom of 1. Therefore, when the convex portion 1a is provided below the bulb 1, the convex portion 1a is provided.
a is the coldest point, and metal or metal halide
As a result, the emission color changes.

In this embodiment, as shown in FIG.
a is provided on the upper part of the bulb 1, and the projection 1 a
Since is heated during the main discharge, it does not reach the coldest point, and even when a discharge gas containing a metal or a metal halide is used, it is possible to prevent a change in emission color. Here, even if the position of the convex portion 1a is not the upper end of the bulb 1, the same effect can be obtained as long as the position is not the coldest point. Other configurations are the same as in the first embodiment.

[0016]

As described above, according to the present invention, a plurality of starting auxiliary electrodes provided near the outer wall surface of the valve and applied with a high-frequency voltage are provided so as to be electrostatically coupled to the internal space of the valve. An outwardly bulging convex portion is formed at a key point on the peripheral wall, and a part of each starting auxiliary electrode is arranged at a position where it is electrostatically coupled to the internal space of the convex portion. It can be reduced near the convex part, and the strong electric field generated around the starting auxiliary electrode near the convex part can act on the discharge gas inside the convex part, and the strong electric field acts on the minute space. This facilitates dielectric breakdown. As a result, there is an advantage that generation of electrons for generating a preliminary discharge is promoted, and the generation of the preliminary discharge can be facilitated. In addition, a preliminary discharge along the starting auxiliary electrode can be easily generated without generating a discharge outside the bulb. Also, after the preliminary discharge occurs, the toroidal induction electric field formed in the bulb by the application of a high-frequency current to the induction coil acts on the preliminary discharge, and can be shifted to the main discharge. It will be easier. As a result of the predischarge being more likely to occur as described above, there is an advantage that the supply energy at the time of starting is reduced, the power supply can be reduced in size, and the overall size can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an embodiment 1 excluding an induction coil.

FIG. 2 is a schematic configuration diagram of Embodiment 2 excluding an induction coil.

FIG. 3 is a schematic configuration diagram showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Valve 1a Convex part 2 Induction coil 3a Starting auxiliary electrode 3b Starting auxiliary electrode 4 High frequency power supply 5 High frequency power supply

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shin Shin Ogawa, Kazuma, Kazuma, Osaka 1048, Matsushita Electric Works, Ltd. References JP-A-1-95462 (JP, A) JP-A-4-56059 (JP, A) JP-B-6-97607 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB Name) H01J 65/04

Claims (1)

(57) [Claims] 1. A high-frequency current is supplied from a high-frequency power supply to an induction coil having a winding wound around the bulb made of a light-transmitting material, and a high-frequency electromagnetic wave is formed inside the winding in the radial direction of the induction coil. In an electrodeless discharge lamp that excites and emits a discharge gas by causing a field to act on a discharge gas sealed in a bulb, a high-frequency voltage is disposed near an outer wall surface of the bulb so as to be electrostatically coupled to an internal space of the bulb. A plurality of starting auxiliary electrodes to which is applied is provided, and a convex portion bulging outward is formed at a key point on the peripheral wall of the valve, and a part of each starting auxiliary electrode is electrostatically coupled to the internal space of the convex portion. An electrodeless discharge lamp, which is disposed at a position.