JPH1140101A - Discharge lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce luminous flux decary, eliminate flickers, and suppress fracturing risks by using tungsten mixed with luminescent materials which are luminescent metals or oxides of luminescent metals or their mixture for producing electrodes. SOLUTION: An electrode 1 or an electrode 2 or both electrodes 1, 2 are made of tungsten, mixed with luminescent materials which are luminescent metals or oxides of luminescent metals or their mixtures. The luminescent materials are luminescent metal single bodies, oxides of the luminescent metal single bodies, or their mixtures. The mixtures include mixture of the luminescent metal single bodies, mixtures of luminescent metal single bodies and oxides, or mixtures of oxides. Two or more types of such materials are mixed based on the purpose. Dysprosium, neodymium, indium, iron, cobalt, etc., are examples for the luminescent metals, and the metals are properly selected according to the application.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge lamp used for optical equipment and general lighting, and more particularly to an improvement of a metal vapor discharge lamp.

[0002]

2. Description of the Related Art Metal vapor discharge lamps (for example, metal halide lamps) are widely used for optical devices such as liquid crystal projectors, OHPs, and projectors, and for general lighting of commercial facilities and general homes. This metal vapor discharge lamp has a very excellent characteristic that its life is 5 to 10 times longer than the light emission by heating a filament such as a halogen lamp. In recent years, there has been a strong demand from users for such metal vapor discharge lamps to further extend their life.

Therefore, as a means for extending the life of the metal vapor discharge lamp, an ultra-high pressure mercury lamp in which the amount of mercury sealed in the lamp is increased (this lamp does not contain a luminescent metal in an arc tube, so that the Corrosion and devitrification inside the arc tube are unlikely to occur.) And bias of the luminous metal in the arc tube due to DC (direct current) lighting (this is because the halide enclosed in the arc tube was ionized and ionized in the arc. In this case, a metal halide lamp has been put to practical use in which the cation or anion is pulled by the cathode or the anode and does not diffuse to the arc tube side) to reduce the devitrification phenomenon of the inner wall of the arc tube. . However, even if the devitrification phenomenon is alleviated, it cannot be said to be sufficient as described later, and further improvement has been required.

As is well known, the above-mentioned ultra-high pressure mercury lamp contains a large amount of mercury in order to improve the luminous efficiency, so that the pressure in the arc tube becomes extremely high during operation, and the rupture of the ultra-high pressure mercury lamp is larger than that of a normal lamp. There is a problem of high risk. In addition, due to the extremely high pressure at the time of lighting, gas convection in the arc tube during lighting is strong, and there is a disadvantage that flicker is easily generated due to the influence of the arc.

On the other hand, in a metal halide lamp of DC lighting, the devitrification phenomenon is alleviated for the above-mentioned reason. The luminous metal encapsulated in the arc tube is gradually running short due to adhesion or reaction with the inner wall of the arc tube,
This causes luminous flux attenuation and shortens the service life of the metal discharge lamp. Although the above-described improvements have been made, the metal discharge lamp still does not sufficiently meet the demands of users.

[0006]

Therefore, according to the present invention, luminous flux attenuation can be reduced by using a luminescent material, that is, tungsten mixed with a luminescent metal or an oxide of the luminescent metal or a mixture thereof, for the electrode. It is an object of the present invention to obtain a discharge lamp free of flicker and having a very low risk of explosion, particularly a metal vapor discharge lamp such as a metal halide lamp.

[0007]

According to a first aspect of the present invention, there is provided a discharge lamp having a pair of electrodes (1) and (2) disposed in an arc tube (3). The electrode (1), the electrode (2), or both electrodes (1) and (2) are formed of tungsten mixed with a luminescent material (4) such as an oxide or a mixture thereof.

(Operation) As described above, tungsten mixed with a light-emitting material (4) such as a light-emitting metal or a light-emitting metal oxide or a mixture thereof is applied to the electrode (1) or the electrode (2) or both electrodes (1). And (2), for example, in a metal halide lamp, a luminescent material originally enclosed
(4) gradually disappears during lighting as described above, but the luminescent material (4) mixed with the electrode (1) or the electrode (2), or the tungsten of both the electrodes (1) and (2). There is no such a case that heat is evaporated by the heat of the arc during lighting and supplied and diffused into the arc tube (3), thereby causing a sudden light flux attenuation unlike the conventional case. The tungsten mixed with the light emitting material (4) can be applied to one electrode (1) or (2) or both electrodes (1) and (2). Luminescent material (4)
Depends on the supply amount. The luminescent material (4) is a luminescent metal alone, a luminescent metal oxide, or a mixture thereof. The mixture includes a mixture of simple luminescent metal, a mixture of simple luminescent metal and oxide, and a mixture of oxides. Two or more kinds of mixing methods can be mixed according to the purpose. The luminescent metal is appropriately selected depending on its use. Examples thereof include dysprosium, neodymium, indium, iron, and cobalt.

A second aspect of the present invention provides an electrode (1) or an electrode of the discharge lamp.
(2) Or, in both electrodes (1) and (2), the light emitting material such as a light emitting metal or a light emitting metal oxide or a mixture thereof.
(4) is mixed in at least one of the electrodes (1) or (2) or the discharge section (11) of (1) and (2). " According to this, the luminescent material (4) is the electrode (1) or
(2) or the whole of both electrodes (1) and (2) or the discharge part (11)
When an arc is generated between the electrodes (1) and (2) by lighting, the discharge part (11) at the tip of both electrodes (1) and (2) is heated, and the luminescent material ( 4) This is more likely to evaporate than tungsten, which is the main constituent metal of the electrodes (1) and (2), to supplement the luminous material (4) in the arc tube (3) consumed by evaporation.

[0010]

FIG. 1 is a sectional view of an embodiment of a double-end type metal vapor discharge lamp for direct current lighting according to the present invention. Although not shown, the present invention is of course applicable to a double-ended metal vapor discharge lamp for AC lighting and a single-ended type. In the case of the AC lighting type, both electrodes (1) and (2) have the same shape, but in the case of DC lighting, one becomes a cathode and the other becomes an anode. In this case, tungsten having a larger diameter is used for the anode than for the cathode. This is the same for the single-ended type. The double-end type arc tube (3) is made of quartz glass and has a substantially spherical or rugby spherical light emitting portion (5). In this embodiment, the light emitting portion (5) has an outer diameter of 15 mm and an internal volume of 1 cc. . On both sides of the light emitting part (5), a substantially rectangular parallelepiped sealing part (6) is formed, and a sealing foil (7) is provided in the sealing part (6).
<< In general, molybdenum metal foil is used. >> and the welding end and electrode of the external lead rod (8) connected to the sealing foil (7)
(1) The welded end of (2) is buried. (9) is the seal mark of the tip tube.

In the present embodiment, a predetermined amount of mercury and argon gas are sealed as a sealing gas in the arc tube (3), and a predetermined amount of dysprosium bromide is used as a light emitting material (4) together with the sealing gas. It is enclosed. The distance between the electrodes is 2 mm. In this embodiment, for direct current lighting, the cathode (1) was made of tungsten mixed with 1% dysprosium as the light emitting material (4), and the anode (2) was made of tungsten only. This lamp has a normal amount of mercury, and the internal pressure at the time of operation is about 1/3 (20 times less than that of a conventional ultra-high pressure mercury lamp).
５０50 atm) and the risk of rupture is low. Further, since the internal pressure at the time of lighting is lower than that of the ultra-high pressure mercury lamp, there is little convection inside the lamp, and flicker hardly occurs. Although the embodiment of the present invention is a metal halide lamp using dysprosium bromide, the type of the luminescent material (4) to be enclosed is not limited. Also, the lighting method is not limited to DC lighting. The method of mixing is not particularly limited, and may be doping, baking, adhesion to the tungsten surface by coating, or any other method. Also, the mixing portion may be the electrode (1) or (2) or the whole of the electrodes (1) and (2), or may be only the discharge portion (11) at the tip where an arc is generated at the time of lighting.

When the metal vapor discharge lamp according to the present invention is turned on by direct current, an arc is generated between the cathode (1) and the anode (2).
(10) occurs. In the arc (10), dysprosium bromide, which is a halide of the luminescent material (4) in the sealed gas, is heated and ionized, ionized and attracted to the cathode (1) or anode (2), respectively. As described in the conventional example,
(1) The amount of the luminescent material (4) and the ions that are unevenly distributed in the vicinity of (2) and move toward the arc tube (3) are reduced. However, this is not the case, and some of the ionized ions diffuse toward the arc tube (3) and are consumed by reacting with the quartz glass constituting the wall surface of the light emitting section (5). Also, if it diffuses and adheres to the bases of the electrodes (1) and (2) and the cold temperature point (low temperature place) of the light emitting part (5), it will not be reheated to the evaporation temperature and will adhere and remain as it is. Become.

[0013] Thus, the light emitting material (4) initially sealed together with the sealing gas is gradually consumed. Meanwhile, the cathode
(1) << Of course, the anode (2) or both electrodes (1) and (2) may be mixed with dysprosium as the luminescent material (4), so that it is heated by the arc (10). The luminescent material (4) evaporates from the part which has been consumed, and makes up for part or all of the consumed luminescent material (4). As a result, light flux attenuation unlike the related art does not occur.

<< Comparison between lamp of the present invention and conventional lamp >>
The lamp of the present invention (a cathode (1) is made of tungsten mixed with 1% dysprosium as a luminescent material (4), and an anode (2)
Was used with no light-emitting material (4), and DC was turned on with an electronic ballast at a lamp power of 350 W to confirm its life. On the other hand, as a life comparison, a conventional lamp was also manufactured and comparative measurement was performed. (Tungsten that does not contain the luminescent material (4) is used for both electrodes (1) and (2).) The following table shows the life results of both lamps.

[0015]

[Table 1]

The luminous flux was attenuated by setting the initial value to 100%, measuring the luminous flux at each time, and graphing the decay rate. Result A is the life result of the lamp of the present invention, and result B is the life result of the conventional lamp. As is clear from the graph, the lamp of the present invention exhibited good results with little luminous flux attenuation.

In the above-described embodiment, the example of the DC lighting is described. However, the same operation and effect can be obtained since the light emitting material (4) is supplied even in the case of the AC lighting.

[0018]

As described above, according to the present invention, the use of tungsten mixed with a luminescent material as an electrode allows the luminescent material to be supplied continuously during lighting, thereby increasing the amount of mercury as in the prior art. There was no need for this, and a long-life lamp with low luminous flux attenuation at a normal mercury amount was obtained. Further, since it is not necessary to increase the amount of mercury as in the case of an ultra-high pressure mercury lamp, the occurrence of flicker is suppressed.

[Brief description of the drawings]

FIG. 1 is a sectional view of a metal vapor discharge lamp according to the present invention.

FIG. 2 is an enlarged partial sectional view of an arc discharge part of FIG.

[Explanation of symbols]

 (1) ... electrode (cathode) (2) ... electrode (anode) (3) ... arc tube (4) ... luminescent material (5) ... luminescent part (6) ... sealing part (7) ... sealing foil ( 8)… External lead rod (9)… Seal mark (10)… Arc

Claims (2)

[Claims] In a discharge lamp having a pair of electrodes disposed in an arc tube, the electrodes are formed of tungsten mixed with a light emitting material such as a light emitting metal, a light emitting metal oxide, or a mixture thereof. A discharge lamp characterized by the above. 2. The discharge lamp according to claim 1, wherein a light-emitting material such as a light-emitting metal, a light-emitting metal oxide, or a mixture thereof is mixed in a discharge portion of at least one of the electrodes.