JP3345879B2 - High pressure mercury vapor discharge lamp and light source device using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a high-pressure mercury vapor discharge lamp used only by an arc tube without using an outer bulb, and more particularly, to a short arc type discharge lamp in which the mercury vapor pressure in the arc tube is increased. Regarding improvement.

[0002]

2. Description of the Related Art In recent years, short arc discharge lamps comprising only a light emitting tube combined with a reflector have been used as a light source for a projection device, a projector and the like. or,
2. Description of the Related Art There has been proposed a liquid crystal projection apparatus in which a small and high-density active matrix liquid crystal device, an optical component, and a light source are combined and driven by input from a personal computer.

A high-pressure mercury vapor discharge lamp disclosed in Japanese Patent Application Laid-Open No. 2-148561 has a mercury vapor pressure of 200.
It is operated at up to 300 atm. When this type of lamp is used as a light source of a liquid crystal projection device, the pressure of the arc tube during lamp operation is high, and in addition, the arc tube receives thermal stress, and cracks occur early, and finally the arc tube bursts. An accident may occur. Furthermore,
Since the pressure of the arc tube is extremely high, there is a possibility that the rupture may occur, and at the same time, a glass-made reflecting mirror or an optical component provided on the front surface may be pierced, thereby destroying an important component in the projection apparatus.

[0004]

SUMMARY OF THE INVENTION In addition, Japanese Patent Laid-Open No. 6-52 (1994)
No. 830 discloses a high-pressure mercury discharge lamp,
By encapsulating mercury, bromine as a halogen, and a rare gas in an arc tube having a predetermined shape, optical characteristics and life characteristics are improved. However, since the amount of bromine to be enclosed is very small, it is insufficient to prevent blackening of the arc tube, and it is difficult to enclose a small arc tube with a small internal volume in manufacturing. .

In view of the above, the present inventor has made various studies and found that the operating voltage in the arc tube during discharge lamp lighting, the amount of bromine sealed in the arc tube, and the diameter of the tungsten electrode core rod sealed at both ends of the arc tube. By defining the correlation between the arc length of the electrode and the lamp current within a predetermined range, it has been confirmed that high-pressure mercury vapor discharge lamps that produce less blackening of the arc tube over the life of the lamp and are easy to manufacture can be obtained. did it.

That is, the blackening of the arc tube is prevented by reducing the operating pressure at an extremely high pressure of 200 to 300 atm and using a large amount of bromine which is relatively reactive to tungsten as the halogen to be sealed. I did it.
Also, in order to shorten the rated life of the discharge lamp (4000 to 5000 hours), the diameter of the electrode core rod between the electrode coils protruding from the electrode embedding part into the discharge space is specified in relation to the lamp current and the like, and the attack by bromine is performed. By narrowing during the rated life period, bending and dropping after the life period,
It is intended to make the lamp inconsistent and prevent accidents such as bursting of the arc tube.

According to the present invention, there is no deterioration in optical characteristics due to blackening of the arc tube during the rated life of the discharge lamp, and no accident such as cracking or rupture of the arc tube occurs.
In particular, an object of the present invention is to provide a high-pressure mercury vapor discharge lamp which is excellent as a light source or a light source device of a video device or a video device.

[0008]

In order to achieve the above-mentioned object, the present invention provides a quartz luminous tube having a pair of electrodes sealed at both ends in an amount of mercury that gives a vapor pressure of 100 to 200 atm when lit. And 1.1 × 10 ^{−5 to} 1.2 × 1 as halogen
0 ^-7 mol / cc of the amount of the rare gas with bromine sealed will be, and the arc length between the electrodes is defined as 0.5 to 1.5 mm, further, a lamp current stabilization during I (A) When the diameter of the electrode core rod between the electrode embedded portion and the electrode coil portion is D (mm) and the arc length is L (mm), 0.2 ≦ LDD / I ≦
0.4. Further, the discharge lamp is buried and used substantially at the bottom side of the spheroidal reflecting mirror.

According to the present invention, a long life is achieved by narrowing the base of the electrode during the rated life and shortening the rated life based on the temperature distribution of the electrode when the high-pressure mercury vapor discharge lamp is turned on and the concentration of the enclosed bromine. The rupture of the arc tube, which often occurs after achieving the above, can be prevented. And even if this discharge lamp is used as a light source for a precision liquid crystal projection device, the lamp can be made a spot by narrowing and dropping the electrodes of the arc tube, so that the optical device inside the projection device It is possible to prevent an unexpected accident of destruction of parts.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a rated power 10 according to the present invention.
It is a side view which shows one Example of a short arc type mercury lamp of 0W. In the figure, reference numeral 1 denotes an arc tube made of quartz glass having an inner diameter of 4 mm.
mm, the inner volume of which is approximately 0.05 cc. The sealing portion 2 is formed at both ends, and the sealing portion 2 has a molybdenum foil 3 having a length of about 20 mm and a width of about 15 mm. A tungsten electrode 4 having a core rod diameter of 0.3 mm and a molybdenum lead wire 5 having a wire diameter of about 0.6 mm are connected to each other through the through hole so that the arc length (distance between the tips of both electrodes) is 1.2 mm. Are located. 10 mg of mercury as a buffer gas, about 13,000 Pa of argon gas as an auxiliary gas for starting, and 1.6 × 10 ⁻⁶ mol / c of bromine as hydrogen bromide in the arc tube configured as described above.
c enclosed. In the figure, reference numeral 6 denotes a base fitted to one end of the arc tube 1, which is fixed to the bottom of a spheroidal reflecting mirror (not shown) via an adhesive to serve as a light source device of a liquid crystal projection device. used.

Next, an experimental example will be described. When a life test was performed on the arc tube using a rated power ballast having a tube input of 100 W and horizontal lighting in which the arc tube axis was substantially horizontal, even after 1000 hours to 2000 hours had passed, a practical problem occurred. It was good without any serious inconvenience. After about 5,000 hours, the base of the electrode core of the arc tube becomes thinner by bromine as an enclosure, and the tip including the electrode coil wound around the tip of the electrode core falls off and falls, causing the lamp to fall. I was disappointed.

On the other hand, for comparison, when a lamp in which bromine as hydrogen bromide was sealed in an amount of 1.0 × 10 ⁻⁷ mol / cc was subjected to a lighting test under the same conditions as above, about 1% was obtained.
2,000 hours, devitrification occurred at the upper part of the arc tube during lighting, and the illuminance was reduced at an early stage. (Comparative Example 1) Further, bromine as mercury bromide was 2.2 × 10 ⁻⁵ mol / c.
When a lighting test was performed on the lamp sealed with the amount of c under the same conditions as above, from the initial lighting period, the emission color was poor for use as a video device such as a liquid crystal projection device,
In addition, there is a problem that the electrode falls early within 1000 hours and becomes a point. (Comparative Example 2)

Table 1 shows the experimental results of the above-described examples and comparative examples.

[0014]

[Table 1]

FIG. 2 is an enlarged view of a main part of the arc tube 1. An electrode 4 sealed at both ends of the arc tube is an electrode coil portion 4 formed by winding a tungsten coil around the tip of an electrode rod 4a.
b. Here, the electrode mandrel 4a of the arc tube sealing portion 2
The diameter of the electrode core rod between the buried portion and the electrode coil portion 4b is Dm.
m, and the arc length between both electrodes is L mm (L = 0.5 to 1.
5) As a result of examining the correlation with the lamp current I (A) at the time of stable lamp operation, 0.2 ≦ LDD / I ≦
By stipulating 0.4, even if bromine is sealed in a larger amount than before, blackening of the arc tube does not occur within the rated life period, and there is no point after the end of the life period. I just need.

When L · D / I <0.2, the tip of the electrode is melted or blackened at an early stage, resulting in a short life.
Further, when L · D / I> 0.4, the required illuminance cannot be obtained, and there is no inconvenience, and lighting of the arc tube may be continued and the arc tube may burst. Further, when the arc length of the arc tube is 0.5 to 1.5 mm, the relational expression between the lamp current at stable time, the diameter of the electrode core rod and the arc length is 0.2 ≦ L ·
D / I ≦ 0.4, 1.1 × 10 ^{−5 to} 1.2 × 10
^-7 mol / cc of bromine is sealed in the lamp,
When a test similar to that described above was performed, good results were recognized as in the example.

In the above embodiment, the short arc mercury lamp has been described. However, almost the same effect can be observed in a high-pressure mercury vapor discharge lamp in which a metal halide, bromine and mercury as halogen, and a rare gas are sealed in an arc tube.

[0018]

As described above, the present invention can satisfy 2,000 hours or more, which is the rated life time as an imaging device or an optical device such as a liquid crystal projection device, and emit light due to blackening of an arc tube. There is an advantage that not only the efficiency does not decrease but also the rupture of the arc tube, which may occur after the elapse of the lifetime, can be prevented.
Then, a light source device with high illuminance effective for video equipment and the like can be obtained without changing the original lamp optical characteristics.

[Brief description of the drawings]

FIG. 1 is a side view showing one embodiment of a short arc type mercury lamp according to the present invention.

FIG. 2 is an enlarged side view of a main part of the arc tube.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Arc tube 2 Sealing part 3 Molybdenum foil 4 Electrode 4a Electrode core rod 4b Electrode coil part 5 Molybdenum lead wire 6 Base

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01J 61/88 H01J 61/20

Claims (2)

(57) [Claims] In a quartz arc tube having a pair of electrodes sealed at both ends, an amount of mercury that gives a vapor pressure of 100 to 200 atm during lighting and 1.1 × 10 ^{−5 to} 1.2 × as halogen. 1
0 ^-7 mol / cc of the amount of the rare gas with bromine sealed will be, and the arc length between the electrodes is defined as 0.5 to 1.5 mm, further, a lamp current stabilization during I (A) When the diameter of the electrode core rod between the electrode embedded portion and the electrode coil portion is D (mm) and the arc length is L (mm), 0.2 ≦ LDD / I ≦
0.4 high-pressure mercury vapor discharge lamp, characterized by being 0.4. 2. The light source device according to claim 1, wherein said discharge lamp is buried substantially at the bottom of a spheroidal reflector.