JP2001243911A - High-pressure discharge lamp and illumination device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-pressure discharge lamp using an electrode, of which impurities are well extracted with high-temperature heat treatment and yet the bare bones of which has substantial mechanical strength. SOLUTION: An electrode axis 1 which makes up a bare bone part of an electrode 10, is furnished with a primary recrystallization layer 1a coated with a secondary crystallization layer 1b and a secondary recrystallization layer 1b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a high-pressure discharge lamp and a lighting device.

[0002]

2. Description of the Related Art Conventionally, an electrode for a high pressure discharge lamp has been subjected to various cleaning and cleaning processes in its manufacturing process in order to prevent impurities present on the electrode surface and in the electrode material from being mixed into the arc tube.
Reduction treatment and high-temperature heat treatment are performed to remove impurities.

[0003] Further, tungsten, which is a high melting point metal used for an electrode for a high pressure discharge lamp, undergoes a high temperature heat treatment to have a large crystal grain size and reduce impurities on the metal surface, thereby increasing the melting point of tungsten. I do. This has the effect of reducing blackening of the high-pressure discharge lamp due to scattering of the electrode material.

[0004] However, as the crystal grain size is increased by the high-temperature heat treatment, such a problem that the electrode is broken from a bonding portion of the crystal which has grown larger occurs.

[0005] Japanese Patent Application Laid-Open No. H11-97166 discloses a heat treatment of an electrode while maintaining the mechanical strength of the electrode.
An electrode for a high-pressure discharge lamp having a crystal grain size of L / W> 5 (L: length of grain size, W: width of grain size) in which at least a portion of the electrode base contacting the arc tube sealing material has L / W> 5 (Conventional Example 1) is described.

[0006]

Since the heat treatment is performed while maintaining the mechanical strength as in Conventional Example 1, even if an electrode is formed so as to limit the crystal grain size, impurities remain without being completely removed. Thus, when a high-pressure discharge lamp is formed, problems such as blackening may occur during the life of the lamp.

[0007] In order to reduce such inconvenience, it is preferable to completely remove impurities, and it is effective to increase the crystal grain size by further performing a heat treatment.

However, increasing the crystal grain size may decrease the mechanical strength. It is considered that this is because the bonding between the crystals becomes weaker as the crystal grain size increases. When the mechanical strength of the high-pressure discharge lamp is reduced, there is a possibility that a problem such as a broken electrode may occur during the manufacturing process or during transportation.

An object of the present invention is to provide a high-pressure discharge lamp using an electrode capable of maintaining a predetermined mechanical strength even when a heat treatment capable of sufficiently removing impurities is performed and the crystal grain size of the electrode material is increased. And

[0010]

A high-pressure discharge lamp according to the present invention comprises a high-melting point metal having a secondary recrystallization layer and a primary recrystallization layer covering the secondary recrystallization layer at least at a root portion. And a translucent container enclosing at least one pair of electrodes.

In the present invention and each of the following inventions, definitions and technical meanings of terms are as follows unless otherwise specified.

As the high-pressure discharge lamp, for example, all high-pressure discharge lamps such as a high-pressure mercury lamp and a metal halide lamp can be applied.

The refractory metal forming the electrode may be a metal such as tungsten, molybdenum or rhenium. When using tungsten metal, aluminum, silicon,
Doped tungsten to which a dopant such as potassium is added, or tritated tungsten to which an electron-emitting substance such as thorium oxide is mixed are also acceptable.

The electrodes are subjected to a high-temperature heat treatment to remove internal impurities in order to suppress blackening of the lamp and the like. The crystal of the electrode material is grown by this high-temperature heat treatment. In order to form an electrode according to the present invention,
First, heat treatment is performed at a temperature at which primary recrystallization is formed on the skin of the electrode. Thereafter, the electrode is further subjected to a high-temperature heat treatment to form a secondary recrystallized layer inside the electrode. At this time, the electrode skin formed by the first heat treatment is formed as a primary recrystallized layer without secondary recrystallization.

[0015] The root of the electrode refers to the portion in contact with the translucent container enclosing the electrode. For example, in an electrode composed of an electrode shaft and a coil, at least a part of the electrode shaft is shown.

The translucent container is formed of a material having translucency, fire resistance and airtightness, such as quartz glass and translucent ceramics, and surrounds the discharge space and hermetically seals the electrodes.

The pair of electrodes are sealed inside the translucent container so as to be spaced apart and opposed to each other. If the translucent container is elongated,
Sealed on both ends. Further, when the light-transmitting container is spherical or elliptical spherical, not only a double sealing structure in which a pair of electrodes are sealed at both ends of the light-transmitting container, but also, if necessary, almost parallel from one end side. A one-sided sealing structure in which the package is separated and sealed can be provided.

In the case of a high-pressure sodium lamp, since a translucent ceramic is used as the translucent container, the electrode is supported on the inner end of a tube of a sealing metal such as niobium which penetrates the translucent container airtightly. Can be.

Further, in the case of a metal halide lamp, quartz glass or translucent ceramic is used as the translucent container. In the case of quartz glass, the electrodes can be sealed by pinch sealing or heat softening and shrinking. As a result, the electrode can be welded at its base end to molybdenum foil embedded in the sealing portion, and can support the periphery of the intermediate portion on quartz glass.

Further, the high pressure discharge lamp configured as described above can be accommodated in the outer tube.

According to the first aspect of the present invention, since the electrode can be sufficiently subjected to high-temperature heat treatment, impurities in the electrode member can be removed. For this reason, the reduction of the melting point of the electrode member due to impurities in the electrode member is reduced, and problems such as blackening due to scattering of the electrode member can be reduced.

Further, since the primary recrystallized layer exists on the skin of the electrode, the mechanical strength of the electrode can be maintained even if the electrode is sufficiently heat-treated. For this reason, it is possible to provide a high-pressure discharge lamp that can reduce defects such as breakage of electrodes during the manufacturing process or during transportation.

According to a second aspect of the present invention, there is provided a lighting device comprising: a lighting device main body; a high pressure discharge lamp according to the first aspect; and lighting means for stably lighting the high pressure discharge lamp.

Illumination means a broad concept that includes any device configured to use the light emission of a high pressure discharge lamp for any purpose. Therefore, it is widely applicable to various uses such as lighting, light projection and photochemical reaction.

For lighting, it is applicable to various indoor and outdoor lighting fixtures.

For light projection, projectors and advertisements
Adapted for floodlighting on displays such as advertisements or signs.

For photochemical reaction, it is applicable to treatment of a photo-curable resin, synthesis of a synthetic resin, and the like.

According to the second aspect of the present invention, it is possible to provide a lighting device having the function of the first aspect.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of a light source device according to the present invention will be described with reference to FIGS. FIG. 1 is a cross-sectional view of an embodiment of an electrode of a metal halide lamp according to the present invention. FIG. 2 is an enlarged sectional view of the same electrode. In addition,
1 are given the same reference numerals.

The electrode 10 includes an electrode shaft 1 and an electrode coil 2. The electrode shaft 1 was made of tritated tungsten in which 1.7% of thorium oxide was mixed. The electrode coil 2 uses doped tungsten having a diameter of 0.4 mm. The electrode shaft 1 has a diameter of 0.6 mm and a length of 11
mm rod shape.

The electrode shaft 1 has a primary recrystallized layer 1a covered with a secondary recrystallized layer 1b. The primary recrystallized layer 1a has a layer thickness of 0.01 mm to 0.05 mm, The crystal grain length of the crystal layer 1a is 0.01 mm to 0.0 mm.
5 mm, and is formed of one to five layers of crystal grains.

The secondary recrystallized layer 1b is composed of crystal grains having a size at least 100 times the crystal grain size of the primary recrystallized layer 1a. Has grown to a width excluding the width of the primary recrystallized layer 1a having the diameter of the electrode 1.

An embodiment of a method for manufacturing such an electrode will be described. The high melting point metal such as tungsten used for the electrode 1 is mainly manufactured by powder metallurgy because it is difficult to manufacture by a normal melting method. With powder metallurgy, after hardening metal powder with large pressure. A metal solid is obtained by firing. Metal solids obtained by powder metallurgy from tungsten powder mixed with thorium oxide are subjected to wire drawing in order to be processed into electrode rods having a predetermined thickness. In the wire drawing process, stretching is performed using a carbon mold while heating at a temperature of 1800 ° C.

FIG. 2 shows a cross section of the electrode after the drawing process.
(A). The primary recrystallized layer 1a has already been formed on the skin of the electrode by heating at 1800 ° C. in the wire drawing process. The inside 1c of the electrode has not been recrystallized yet, and is composed of fibrous crystals.

Thereafter, the electrode 10 is cut to the length of the electrode shaft 1 and wound around the electrode coil 2 to obtain the structure of the electrode 10 shown in FIG.

Further processing is performed in the state of the electrode 10. First, a reduction treatment is performed by heating at 1800 ° C. for 15 minutes in a hydrogen atmosphere. Thereafter, heat treatment is performed at a high temperature of 2500 ° C. for 10 minutes in a vacuum atmosphere. This high-temperature heat treatment removes impurities inside the electrode 10 and forms a secondary recrystallized layer 1a of the electrode.

FIG. 2B shows a cross-sectional view of the electrode after this processing. A secondary recrystallized layer 1b is formed inside the electrode shaft. The primary recrystallized layer 1a maintained the primary recrystallized state without crystallization progressing under the above conditions even when re-heated. The crystal grain size of the secondary recrystallized layer 1b was the largest, which resulted in the crystal being grown to a width of 0.3 mm.

The mechanical strength of the electrode 10 of this embodiment was compared. The electrode used for comparison was the same as the electrode of the present embodiment in both the material size and the material size. However, the heat for forming the secondary recrystallization was further increased to 2800 ° C. for 15 minutes.
An electrode in which secondary recrystallization was grown up to the primary recrystallization layer of the electrode skin was used.

In the case of the electrode of the comparative example, the breaking strength of the electrode is
5 MPa or less, the electrode 1 of the present embodiment
When 0 was used, the strength was 1.5 times that of 1.5 MPa.

This is because the mechanical strength is maintained by the bonding between the crystals of the primary recrystallized layer 1 a having a fine crystal grain size formed on the skin of the electrode shaft 1, and the secondary crystal inside the electrode shaft 1 is maintained. This is considered to be because the layer 1b can be mechanically protected.

Next, as a second embodiment, a metal halide lamp using the electrode 10 manufactured in this way is shown in FIG.
This will be described with reference to FIG.

In the figure, IB is an arc tube, OB is an outer tube,
B is a base. The metal halide lamp shown in the figure is vertically lit in a lighting state such that the base B is positioned above.

The arc tube IB includes a light-transmitting discharge vessel 3, a pair of upper and lower electrodes 10, and an ionizing medium not shown in the drawing.

The translucent discharge vessel 3 is made of quartz glass and has pinch seal portions 31 at both ends. A heat insulating film 12 is applied to the outer surface of the translucent discharge container 3 on the lower side during lighting.

The electrode 10 has its base end welded to a molybdenum foil 32 airtightly embedded in a pinch seal portion 31. The auxiliary electrode 11 is buried in the pinch seal portion 31 like the electrode 10 on the upper side during lighting.

The ionizing medium comprises a luminescent metal halide, a rare gas and mercury.

The outer tube OB is made of hard glass, houses the arc tube IB therein, and is filled with nitrogen of about 53 kPa at room temperature. Cap B is made of E39 screw cap,
It is attached to the end of the outer tube OB. The base B is connected to each of the electrodes 10 via a pair of internal introduction conductors 4a and 4b.
It is responsible for supplying electricity to

An upper support frame 5 and a lower support frame 6 are provided inside the outer tube OB to fix the arc tube IB at a predetermined position in the outer tube OB.

The upper support frame 5 supports the upper part of the arc tube IB and electrically connects the electrodes 10, and includes a U-shaped conductor 51, a support band 52 and a connection conductor 53. The base of the U-shaped conductor 51 is welded to the internal introduction conductor 4a. The support band 52 surrounds the pinch seal portion 31 on the upper side of the arc tube IB and is welded to the side of the U-shaped conductor 51. The connection conductor 53 is electrically connected to the upper support frame 5 and the lower support frame 6.
The auxiliary electrode 11 of the arc tube IB is welded to the molybdenum foil 32 in the pinch seal portion 31 and is electrically connected to the U-shaped conductor 5a via the current limiting resistor 13.

The lower support frame 6 supports the lower portion of the arc tube IB and electrically connects the electrodes 10, and includes a U-shaped conductor 61, a support band 62, a connection conductor 63, and a spring piece 63. .

The U-shaped conductor 61 and the support band 62
It has the same structure as the lower support frame 5, but in a vertically inverted relationship. The spring piece 64 is formed of the U-shaped conductor 6.
1 and the tip is held at a predetermined position in the outer tube OB.

The metal halide lamp of this embodiment was turned on and the occurrence of blackening was observed. In the metal halide lamp of the present embodiment, a good luminous flux maintenance factor was maintained without blackening even after 9000 hours, when blackening occurs in a metal halide lamp using a conventional electrode.

This is because the high-temperature heat treatment of the electrode 10
It is considered that the impurities inside the electrode 10 were removed and the scattering of the members of the electrode 10 was suppressed. In addition, since the mechanical strength of the electrode 10 was sufficiently ensured, the bending of the electrode in the manufacturing process and transportation could be reduced.

Next, a third embodiment of the present invention will be described. In the present embodiment, the electrode of the first embodiment is the same as that described in the first embodiment except that the material of the electrode shaft is doped tungsten.

A method for manufacturing the electrode 10 in this embodiment will be described. Drawing process and electrode shaft 1 after drawing
, The electrode coil 2 is wound, and the reduction process is performed in a hydrogen atmosphere in the same process.

Thereafter, the electrode 10 is subjected to a high-temperature heat treatment. The temperature condition of the heat treatment is different from that of the first embodiment. In this embodiment, the high temperature heat treatment is performed at 2000 ° C. in a vacuum atmosphere.
By performing the process for 0 minutes, the primary recrystallized layer 1a can be formed on the skin of the secondary recrystallized layer 1b as in the first embodiment.

The electrode 10 thus formed also has a mechanical strength of 15 kPa, which is 1.5 times higher than that of the electrode in which the skin of the primary recrystallized layer is not formed. Also, when the electrode 10 of the present embodiment was incorporated into a metal halide lamp, a good luminous flux maintenance ratio was secured without blackening during the lifetime.

A third embodiment of the present invention will be described with reference to FIG. FIG. 3 shows a lighting device 7 equipped with a metal halide lamp according to the second embodiment. The same parts as those in FIG. 1 are denoted by the same reference numerals.

The lighting device 7 includes a reflection shade 71, a socket 72
And a ballast 73 and the like. The base 4 of the metal halide lamp is used by being mounted on a socket 72 of a lighting device. A secondary output terminal of a ballast 73 is connected to the socket 72 to supply power to the metal halide lamp. The lighting device 7 is supported by a ceiling surface 70.

[0060]

According to the first aspect of the present invention, since the electrode can be sufficiently heat-treated, impurities in the electrode member can be removed, and the melting point of the electrode member due to the impurities in the electrode member decreases. Thus, problems such as blackening due to scattering of the electrode member can be reduced.

Since the primary recrystallized layer exists on the skin of the electrode, the mechanical strength of the electrode can be maintained even if the electrode is sufficiently heat-treated. For this reason, it is possible to provide a high-pressure discharge lamp that can reduce defects such as breakage of electrodes during the manufacturing process or during transportation.

According to the second aspect of the present invention, it is possible to provide a lighting device having the function of the first aspect.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of first and third embodiments of an electrode of a metal halide lamp according to the present invention.

FIG. 2 is an enlarged sectional view of the same electrode.

FIG. 3 is a front view of a metal halide lamp according to a second embodiment of the present invention.

FIG. 4 is a sectional view of a lighting device according to a fourth embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Electrode axis 1a ... Primary recrystallized layer 1b ... Secondary recrystallized layer 2 ... Electrode coil 10 ... Electrode IB ... Arc tube OB ... Outer tube

Claims (2)

[Claims] An electrode comprising a secondary recrystallized layer and a primary recrystallized layer covering the secondary recrystallized layer formed of a high melting point metal provided at least in a root portion; and a transparent electrode formed by sealing the electrode. A high-pressure discharge lamp, comprising: a light container; 2. A lighting device comprising: a lighting device body; a high-pressure discharge lamp according to claim 1; and lighting means for stably lighting the high-pressure discharge lamp.