JP3017582B2 - Electrodeless lamp - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method in which a high-frequency electromagnetic field is applied to a discharge gas sealed in a bulb from outside the bulb without an electrode inside the bulb to generate an annular discharge in the bulb. The present invention relates to an electrodeless discharge lamp in which a discharge gas is excited to emit light.

[0002]

2. Description of the Related Art Conventionally, an electrodeless discharge lamp has been known in which a high-frequency electromagnetic field is applied to a discharge gas sealed in a bulb to generate an annular discharge in the bulb to excite the discharge gas to emit light. ing. Since this type of electrodeless discharge lamp has features such as small size, high output, and long life, it has been researched and developed in various places, and various uses as a high output point light source are considered.

As shown in FIG. 3, an electrodeless discharge lamp includes a bulb 1 formed of quartz glass or the like, and an induction coil 2 having a winding wound around the bulb 1. A device in which an inner high-frequency magnetic field acts on the discharge gas sealed in the bulb 1 has been considered. The discharge gas is a rare gas or a mixture of a rare gas and a luminescent substance. When a high-frequency current is supplied from the high-frequency power supply 4 to the induction coil 2, a high-frequency magnetic field is formed so as to link the induction coil 2. A ring-shaped induction electric field interlinking with the high-frequency magnetic field is generated. When the induced electric field is generated, the discharge gas is ionized and an annular discharge is generated. When the annular discharge occurs, the discharge gas excites and emits light, and an optical output is taken out.

In order to start the electrodeless discharge lamp having such a configuration, it is necessary to apply a high voltage to the induction coil 2. ing. Therefore, a configuration has been considered in which the auxiliary electrode 3 that is electrostatically coupled to the internal space of the bulb 1 is disposed on the outer surface of the bulb 1, and a high-frequency power supply 5 applies a high-frequency voltage between the auxiliary electrode 3 and the ground. I have. In this configuration, when a high-frequency voltage is applied to the auxiliary electrode 3, a high-frequency electric field is generated around the auxiliary electrode 3, and the high-frequency electric field causes a preliminary discharge in the bulb 1. That is, the electrons accelerated by the high-frequency electric field generated around the auxiliary electrode 3 collide with the atoms of the discharge gas to ionize them, and by repeating such a phenomenon, it is sufficient to maintain the discharge. When the electrons are supplied, the streamer advances from the auxiliary electrode 3 and a preliminary discharge occurs near the auxiliary electrode 3. In such a preliminary discharge, since the auxiliary electrode 3 is monopolar, one end is restricted by the auxiliary electrode 3 but the other end is a free end.
It can move relatively freely. The high-frequency power supplies 4 and 5 include a high-frequency generator including a high-frequency oscillator, an amplifier that amplifies power of a high-frequency output, and a matching unit that matches impedance.

By providing the auxiliary electrode 3 as described above, in the preliminary discharge, the discharge path 7 extends in a direction substantially orthogonal to the auxiliary electrode 3 as shown in FIG. When a high-frequency current is applied to the coil 2, the discharge path 7 is formed in an arc shape along the induced electric field as shown in FIG. Further, as the discharge path 7 progresses, FIG.
A ring-shaped discharge path 7 is formed as shown in FIG. In other words, the generation of the preliminary discharge facilitates the transition to the annular discharge, and facilitates the start even with the use of a relatively small power source.

[0006]

According to the above arrangement, the auxiliary electrode 3 is provided and the preliminary discharge is generated before the annular discharge is generated, so that the starting is relatively easy. However, as described above, lighting is performed through three stages, that is, the stage of the preliminary discharge, the stage of bending the discharge path 7 along the induced electric field from the preliminary discharge, and the stage of the generation of the annular discharge. In the middle of the discharge, a relatively large energy is required to develop the discharge path 7. That is, in the annular discharge, the discharge path 7 has a loop shape and the discharge gas is ionized in the discharge path 7, so that the discharge state can be maintained with relatively small energy.
In the process of shifting from the preliminary discharge to the annular discharge, it is necessary to supply energy sufficient to ionize the discharge gas from the leading end of the discharge path 7 from the induction coil 2 and the auxiliary electrode 3, so that a relatively large energy is required. It is. Under such circumstances, it is required to further facilitate starting.

An object of the present invention is to satisfy the above-mentioned requirements, and an object of the present invention is to provide an electrodeless discharge lamp excellent in startability.

[0008]

According to the present invention, in order to achieve the above-mentioned object, a high-frequency current is supplied from a high-frequency power supply to an induction coil in which a winding is wound around the outer periphery of a valve made of a light-transmitting material. In a non-electrode discharge lamp that excites and emits a discharge gas by applying a high-frequency electromagnetic field formed inside a winding in a radial direction of a coil to a discharge gas sealed in a bulb, a high-frequency voltage is applied to the bulb. A single-pole auxiliary electrode capable of generating a preliminary discharge in which only one end is restrained is disposed on the outer surface of the bulb so as to be electrostatically coupled to the interior space of the bulb. A regulating wall is formed at a position facing the auxiliary electrode to form a recess having an open surface facing the auxiliary electrode, and the regulating wall controls the progress of the discharge path of the preliminary discharge caused by application of the high-frequency voltage to the auxiliary electrode. It is to win.

[0009]

According to the above construction, a single-pole auxiliary electrode capable of generating a preliminary discharge in the bulb when a high-frequency voltage is applied is provided on the outer surface of the bulb so as to be electrostatically coupled to the interior space of the bulb. Because of the arrangement, a preliminary discharge can be generated by the auxiliary electrode before a high-frequency current is applied to the induction coil to excite and discharge the discharge gas. Here, in the portion of the bulb facing the auxiliary electrode, a regulating wall is provided which forms a recess whose surface facing the auxiliary electrode is open, and the preliminary discharge enters the recess of the regulating wall. Since the progress of the discharge path is regulated, when a high-frequency current is applied to the induction coil, the transition to the annular discharge can be made within a relatively small area. That is, as compared with the case where the discharge path extends over almost the entire inner space of the bulb, the energy required for the development of the discharge path is reduced, and it is possible to shift to the annular discharge with relatively small energy. It becomes. As a result, the transition from the preliminary discharge to the annular discharge becomes very easy, and the startability is improved.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, a bulb 1 is formed in an airtight spherical shape by a light-transmitting material such as quartz glass. It is enclosed. The winding of the induction coil 2 is wound around the outer peripheral surface of the valve 1.
Here, the induction coil 2 is wound three turns,
The number of turns is not particularly limited as long as the number of turns is one or more. A single-pole auxiliary electrode 3 is arranged on the outer peripheral surface of the bulb 1 in close contact or close proximity, so that the auxiliary electrode 3 can be electrostatically coupled to the internal space of the bulb 1. The auxiliary electrode 3 is provided within the width of the induction coil 2 in the axial direction of the induction coil 2. In valve 1
As shown in FIG. 1B, a cylindrical regulating wall 6 having a recess 6 a whose surface facing the auxiliary electrode 3 opens is formed at a position facing the auxiliary electrode 3. The axial direction of the regulating wall 6 is arranged so as to coincide with the axial direction of the induction coil 2, and both axial ends of the regulating wall 6 are fixed to the inner peripheral surface of the valve 1.

The induction coil 2 is supplied with a high-frequency current from the first high-frequency power supply 4 to generate a high-frequency magnetic field, and the high-frequency magnetic field acts on a discharge gas inside the bulb 1 to generate an annular discharge. The gas is excited to emit light. That is, a ring-shaped induction electric field is generated in the bulb 1 by the high frequency magnetic field, and the discharge plasma generated in the bulb 1 by the induction electric field rotates in the bulb 1.

A high-frequency voltage is applied between the auxiliary electrode 3 and the ground by a high-frequency power supply 5 (see FIG. 3), as in the conventional configuration. In some cases, a preliminary discharge occurs. By the way, when the preliminary discharge is generated by the auxiliary electrode 3, the tip of the discharge path of the preliminary discharge is
Will get inside. When a high-frequency current is applied to the induction coil 2 in this state, the discharge path tends to develop in an arc due to the induced electric field generated in the bulb 1. Since it is inside, the discharge path forms a loop in the recess 6a. That is, the transition to the annular discharge is performed in a relatively short path. After the transition to the lighting state due to the occurrence of the annular discharge, the light emitting state is maintained without applying a high frequency voltage to the auxiliary electrode 3. At this time, the discharge path of the annular discharge moves to a portion where the electric field strength is large in the induced electric field generated in the bulb 1, so that the discharge path is formed between the inner peripheral surface of the bulb 1 and the outer surface of the regulating wall 6. A path is formed.

As described above, since the transition from the preliminary discharge to the annular discharge is performed through a very short path limited in the recess 6a of the regulating wall 6, the transition from the preliminary discharge to the annular discharge is performed. Less energy is required and starting is easier. For example, assuming that the supply power to the induction coil 2 is about 120 W in a state where the regulating wall 6 is not provided, the provision of the regulating wall 6 enables the starting to be performed with a supply power of about 80 to 100 W. .

In the above embodiment, the regulating wall 6 is formed in a cylindrical shape. However, as shown in FIG. 2A, the regulating wall 6 may be formed in a cylindrical shape having a cross-sectional shape in which a part of a semicircle is opened. As shown in (b), it can be formed in a tubular shape having a cross-sectional shape in which a part of a rectangle is opened. As the discharge gas, a single gas or a mixed gas may be used, and the gas pressure is not limited to 100 Torr. Further, the size and shape of the auxiliary electrode are not particularly limited. Further, the valve 1 is not limited to a spherical shape, and may be any type.

[0015]

According to the present invention, as described above, a single-pole auxiliary electrode capable of generating a preliminary discharge in a bulb when a high-frequency voltage is applied is electrostatically coupled to the interior space of the bulb. Since it is arranged on the outer side surface of the inductive coil, there is an advantage that a preliminary discharge can be generated by the auxiliary electrode before a high-frequency current is applied to the induction coil to excite and discharge the discharge gas. In addition, a regulating wall is formed at a portion facing the auxiliary electrode in the bulb to form a recess having an open surface facing the auxiliary electrode, and the preliminary discharge enters the recess of the regulating wall and discharges. Since the progress of the path is regulated, when a high-frequency current is supplied to the induction coil, the transition to the annular discharge can be made within a relatively small area. That is, as compared with the case where the discharge path extends over almost the entire inner space of the bulb, the energy required for the development of the discharge path is reduced, and it is possible to shift to the annular discharge with relatively small energy. It has the effect of becoming. As a result, the transition from the preliminary discharge to the annular discharge becomes very easy, and the startability is improved.

[Brief description of the drawings]

FIG. 1A is a schematic configuration diagram showing an embodiment, and FIG. 1B is a plan view of the same.

FIGS. 2A and 2B are plan views showing other embodiments.

FIG. 3 is a schematic configuration diagram of an electrodeless discharge lamp according to the present invention.

FIG. 4 is an operation explanatory diagram showing a development state of a discharge path at the time of starting the electrodeless discharge lamp according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Valve 2 Induction coil 3 Auxiliary electrode 4 High frequency power supply 5 High frequency power supply 6 Regulatory wall 6a recess

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shin Shin Ogawa, Kazuma, Kazuma, Osaka 1048, Matsushita Electric Works, Ltd. ) References Hikaru 1-159356 (JP, U) (58) Field surveyed (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 may be applied to generate a preliminary discharge in which only one end is restricted in the bulb. A single-pole auxiliary electrode is disposed on the outer surface of the bulb so as to be electrostatically coupled to the internal space of the bulb, and a portion of the bulb facing the auxiliary electrode is opened at a portion facing the auxiliary electrode. An electrodeless discharge lamp characterized in that a regulating wall is formed to form a recess, and the progress of a discharge path of a preliminary discharge generated by application of a high-frequency voltage to an auxiliary electrode is regulated by the regulating wall.