JPH07105906A - Short arc metal halide lamp - Google Patents

Abstract

PURPOSE:To provide a short arc metal halide lamp optimum as a light source for use in a video imaging apparatus, with which transparency loss of the light emitting tube of the lamp is less likely, little risk exists of impairing the lifetime characteristics, a good light emission characteristic is maintained, and drop of the lightness on the projection plane is null, even though the interelectrode distance of the two ends of light emitting tube is made shorter and the wall surface load is heightened. CONSTITUTION:Besides a rare gas and mercury, at least displosium halide and tin halide as light emitting metal are encapsulated in a light emitting tube of a short arc metal halide lamp concerned. The halogen consists of iodine and bromine, and their contents are such that B/A=0.05-0.35, where A is total encapsulated metal amount in mol excluding mercury and B is tin amount in mol, while D/C=0.05-0.5 where C is total iodine amount and D is bromine amount in mol.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a short arc metal halide lamp mainly composed of an arc tube without an outer tube and used mainly as a light source for video equipment or optical equipment. Regarding improvement.

[0002]

2. Description of the Related Art Conventionally, a short arc metal halide lamp composed of only an arc tube without using an outer tube has been used as a light source for an overhead projector, a projector or a liquid crystal projector. In such a lamp, a reflecting mirror is attached to one end of an arc tube so that light can be easily controlled. In this case, the arc length between both electrodes of the arc tube is 5 mm
It is configured to be similar to a point light source by shortening it to some extent.

In addition, a lamp for a liquid crystal projector has a color temperature close to that of a cathode ray tube of a television due to its application, and is a luminescent metal which is a luminescent metal having a good color reproducibility so that light emission is relatively well balanced over the entire visible wavelength range. A lamp that uses sium, neodymium, or the like, and is closer to a point light source by shortening the distance between electrodes is ideal because of the light distribution efficiency of emitted light.

[0004]

By the way, in the case of a lamp in which at least dysprosium halide is enclosed as a luminescent metal, the vapor pressure of dysprosium is relatively low, so that a well-balanced luminescence is obtained in order to obtain well-balanced luminescence. Is made small and the wall load is made high so that the enclosed metal emits light sufficiently.

However, if the wall load of the arc tube is increased and the arc length is shortened to obtain satisfactory light emission characteristics,
The following problems occur. Currently, even the mainstream lamps are already under a high load of about 60 W / cm ² , and if the load is further increased further, the reaction between the quartz glass, which is the arc tube material, and the enclosed metal halide is accelerated. The devitrification phenomenon of the arc tube becomes remarkable, and the light emission characteristics and life characteristics are deteriorated. In addition, when the distance between the electrodes is shortened, the electrodes are overloaded and the electron emitting material deposited on the electrodes is evaporated and scattered, or the electrode mandrel is melted, resulting in blackening or a short life of the arc tube. Then, there is a problem that the illuminance on the projection surface is reduced early and the lamp has a short life.

The present invention has been made in view of the above, and even if the distance between the electrodes of the arc tube is shortened and the wall load is increased, the devitrification phenomenon of the arc tube is small and the life characteristics are not deteriorated. It is an object of the present invention to provide a short arc metal halide lamp that is capable of maintaining excellent light emission characteristics and is optimal as a light source for video equipment and the like that does not reduce the brightness on the projection surface.

[0007]

SUMMARY OF THE INVENTION The present invention comprises only an arc tube in which an outer tube is not provided and sealing portions are formed at both ends, and a main electrode is sealed at both ends thereof to serve as a starting auxiliary gas. A rare gas and mercury as a buffer gas are enclosed, and at least dysprosium halide (DyX) is used as a luminescent metal.
₃ ) and tin halide (SnX ₂ ), and the halogen consists of iodine and bromine, and the amount of tin B (mol) B / A relative to the total amount A (mol) of the enclosed metal excluding the mercury.
= 0.05 to 0.35, and the bromine amount D (mol) D / C = 0.05 to 0.5 with respect to the total iodine amount C (mol). In addition, a reflecting mirror having a reflecting surface such as a spherical surface, a spheroidal surface, and a paraboloid of rotation is integrally or detachably attached to one sealing portion of the arc tube.

[0008]

As described above, by defining the amount of tin with respect to the total amount of the enclosed metal containing dysprosium halide in the above range, the enclosed metal and the quartz glass (silicon) by adding tin are added.
The devitrification of the arc tube can be delayed by suppressing the reaction with. Further, by using iodine and bromine as halogens constituting the metal halide and defining iodine in the above range in a larger amount than bromine, the reaction between iodine and the electrode material due to the addition of bromine can be suppressed to prevent the consumption of the electrode. . Further, by combining with a reflecting mirror, it is possible to further improve the optical characteristics with respect to the projection surface.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. Fig. 1 is a side view of a metal halide lamp. In Fig. 1, reference numeral 1 is a quartz arc tube tare, and the central part of the arc tube has a spherical shape. The maximum outer diameter is 11 mm, the maximum inner diameter is 9 mm, and the internal volume is about It is 0.5 CC. Reference numeral 2 is an electrode connected through molybdenum foil 3 at both ends of the arc tube, and the distance between the electrodes 2 and 2 is set to 5 mm. 4 is an external lead wire made of molybdenum connected to the molybdenum foil 3, 5 is a welded portion, and 6 is an exhaust pipe tip-off portion.

In the arc tube, as a luminescent metal, dysprosium iodide, neodymium iodide, cesium iodide, tin bromide and mercury bromide together with 200 toor as a predetermined amount of mercury starting auxiliary gas as a buffer gas. It is filled with argon gas. Although not shown, one end of such an arc tube is integrally attached to the bottom of a reflecting mirror having a reflecting surface such as a spherical surface, a spheroidal surface, or a paraboloid of revolution and having an opening at one end to reflect light. It constitutes a metal halide lamp with a mirror. An electronic ballast is used to turn on AC power at 150 W, and the wall load at this time is about 60.
W / cm ² .

In the present invention, dysprosium halide (DyX ₃ ) as a luminescent metal and tin halide (SnX ₂ ) are encapsulated, and the amount of tin B (moles) relative to the total amount A (moles) of encapsulated metal excluding mercury. ), B / A = 0.05-
0.35, and bromine amount D relative to total iodine amount C (mol)
(Mol) and D / C = 0.05 to 0.5 are specified, but an experiment conducted for this setting will be described. First, have dimensions of the Example, DyI ₃ as additives constituting in Example within the arc tube, NdI _3, C
A lamp in which sI, SnBr ₂ , and HgBr ₂ were enclosed together with mercury and argon gas was produced, and the emission characteristics and the life characteristics were compared. Table 1 shows the total amount of enclosed metal excluding mercury A
The values of B / A and D / C are shown when the amount of tin (mol) relative to (mol) and the amount of bromine (mol) relative to the total iodine amount C (mol) of the halide are changed. Also, as comparative examples, a lamp (No 1) that does not use tin and bromine and a lamp (No 2) that does not use tin were produced.

When these lamps were turned on and the light emission characteristics were divided into blue B, green G and red R to check the color balance, good results were obtained. In addition, B: 410
500 nm, G: 500 to 570 nm, R: 580 to 7
The wavelength range was 80 nm.

[0013]

[Table 1]

Therefore, each of the lamps is fixed to the bottom of the spheroidal reflector to form a short arc metal halide lamp device, which is projected on a 40-inch screen and is set so that the illuminance ratio and the average illuminance are constant. The lamp life test was performed. The average illuminance was the average value of the illuminance at the center of the 40-inch screen divided into 9 equal parts. The lighting condition was such that the lighting was on for 2 hours and 45 minutes and turned off for 15 minutes. Then, assuming that the average illuminance at the start of lighting is 100%, Table 2 shows the ratio (%) of the average illuminance with the passage of lighting time. (Hereafter, margin)

[0015]

[Table 2]

As is clear from Table 2, when a general lamp (No1) is used as a standard, the average illuminance maintenance rate after lighting for 1000 hours is about 50%, so the No2 and No8 lamps have almost no effect. Not observed, and the lamp of No. 9 became a defect because the electrode of the arc tube was significantly worn out before the 500 was turned on and the electrode melted. On the other hand, No3 to No7
As in the above lamp, by adding a predetermined amount of tin as a light emitting metal and a predetermined amount of bromine as a halide, it is possible to suppress the devitrification phenomenon caused by the reaction between the wall surface of the arc tube and the rare earth metal that occurs during lamp lighting. In addition, it is possible to prevent the blackening of the arc tube and improve the average illuminance maintenance rate by supplementing the electrode material tungsten, which scatters on the wall surface of the arc tube when the lamp is lit for a long time, with active bromine. it can.

In the present invention, dysprosium halide (DyX ₃ ) and tin halide (S
nX ₂ ) is enclosed and the total amount of enclosed metal excluding mercury is A (mol)
Of tin with respect to B (mol), B / A = 0. O5-0.3
However, if the B / A is less than 0.05, the devitrification preventing effect of the arc tube due to the addition of tin halide is not recognized, and if it exceeds 0.35, the lighting time elapses.
On the contrary, devitrification occurs due to the liquid phase of tin halide, resulting in a decrease in screen illuminance. Further, the bromine amount D (mol) relative to the total iodine amount C (mol) and D / C = 0.05 to 0.5 are specified, but when D / C is less than 0.05, the arc tube is formed by bromine. There is almost no tungsten deposition effect on the wall surface, and no blackening prevention effect is observed. If it exceeds 0.5, the active excess bromine reacts with the tungsten at the base of the electrode to cause wear of the electrode mandrel in a short time, resulting in a defect of the lamp.

Although the Dy-Nd-Cs-based lamp has been described as an arc tube additive in the above embodiment, other additives such as thallium Tl, indium In, scandium Sc, and an alkali metal iodide are used together with dysprosium. Almost the same effect can be seen with a lamp containing at least one of the above. Further, although tin is easily encapsulated in the form of bromide from the viewpoint of production, tin iodide may be used, and bromine is not in the form of mercury bromide, but the encapsulated metal such as dysprosium bromide DyBr ₃ is in the form of bromide. May be enclosed in.

[0019]

As described above, in the short arc metal halide lamp according to the present invention, the devitrification phenomenon of the arc tube is reduced and the life characteristics of the lamp are reduced by defining the kind and the amount of the arc tube filled material. It is favorable, and it is possible to obtain an optimal lamp as a light source for a video equipment, which has advantages such as a decrease in brightness on the projection surface even after lighting for a long time and a good light emission characteristic.

[Brief description of drawings]

FIG. 1 is a side view showing an embodiment of a short arc metal halide lamp according to the present invention.

[Explanation of symbols]

 1 Tare of arc tube 2 Electrode 3 Molybdenum foil 4 Molybdenum external lead wire 5 Welding part 6 Exhaust pipe tip off part

Claims (2)

[Claims] 1. A noble gas as a starting auxiliary gas and a mercury as a buffer gas, which is composed only of an arc tube having an outer tube and sealing parts formed at both ends, and main electrodes are sealed at both ends. And at least dysprosium halide (DyX ₃ ) as a light-emitting metal and tin halide (S
nX ₂ ) and the halogen is a short arc metal halide lamp composed of iodine and bromine, and the amount of tin is B relative to the total amount A (mol) of the enclosed metal excluding mercury.
(Mol), B / A = 0.05 to 0.35, and the amount of bromine D (mol), D / C = 0.0 with respect to the total amount of iodine C (mol).
A short arc metal halide lamp characterized in that each is enclosed in an amount of 5 to 0.5. 2. The short arc metal halide according to claim 1, wherein a reflecting mirror having a reflecting surface such as a spherical surface, a spheroidal surface, and a paraboloid of revolution is integrally or detachably attached to one sealing portion of the arc tube. lamp.