JP2001319616A - Discharge lamp and illuminating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a d.c. discharge lamp with long-life property that prevents electrodes from wearing, to eliminate fluctuation and initial performance from lowering. SOLUTION: This d.c. discharge lamp has a pair of tungsten electrodes, an anode and a cathode, oppositely disposed in a discharge chamber made of a nonconductive material. When denoting area of flat tip (spot) of the said anode as S1 (mm2) and current value at lighting as I1 (A), 0.1<=S1/I1<=0.4 is valid.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an anode and a cathode.
The present invention relates to a direct current type discharge lamp having two electrodes, and to an illumination device using the discharge lamp.

2. Description of the Related Art The performance of a high-pressure mercury vapor discharge lamp capable of withstanding high temperature and high pressure, comprising a discharge vessel made of a non-conductive material and substantially enclosing mercury, a rare gas, and a halogen and having a tungsten electrode. In particular, by controlling the spot configuration of the discharge lamp electrode and trace elements in the base metal material, it is possible to prevent electrode wear, prevent flickering, prevent the initial performance of the lamp from deteriorating, and improve long-life characteristics. It relates to a high-pressure mercury lamp structure suitable for obtaining.

[0003]

2. Description of the Related Art For example, in a projection type display device represented by a liquid crystal projector, a reflector is provided for a light source to form parallel light, and a projected image is projected and formed on a screen through several tens of lens interfaces. A method of imaging is adopted. For this reason, high luminance performance is required for the light source, and a metal halide lamp in which mercury and a metal halide are sealed has been used, and the screen illuminance has been improved by shortening the gap and the like.

[0004] Against this background, a high-pressure mercury lamp having an extremely high mercury vapor pressure has recently been proposed in place of a metal halide lamp, as disclosed in JP-A-6-52830. The high-pressure mercury lamp has a small size and high luminance performance capable of suppressing the spread of the arc with a short gap together with the high mercury vapor pressure. In this lamp, a pair of tungsten electrodes are opposed to each other in an elliptical spherical arc tube at the center of a quartz glass discharge vessel, and mercury, a discharge gas, and the like are sealed as a light emitting substance. At both ends of the arc tube, molybdenum foil conducting to the tungsten electrode is arranged, and the quartz glass that is the discharge vessel is welded to seal the mercury vapor pressure, achieving higher brightness than ever before as a lamp. .

Further, Japanese Patent Application Laid-Open No. 8-153487 discloses a metal halide lamp. In this prior art document, with respect to the spot shape of the tip of the anode of the tungsten electrode, 0.045 <S / I (mm ² /A)<0.08 is specified, and the scraping angle of the anode tip is set to 45 degrees or more, which causes flickering. The configuration as a metal halide lamp without the lamp is introduced.

Further, Japanese Patent Application Laid-Open No. 5-290802 discloses a composition of an electrode for a discharge lamp. This prior art document is characterized in that the base metal of a tungsten electrode containing a rare earth oxide as an emitter substance contains potassium in an amount of 10 ppm by weight or more with respect to the tungsten base metal. A method is described in which grain boundary control is performed to make the supply of the emitter material smooth, to stabilize the arc discharge, and to prevent flicker.

[0007]

SUMMARY OF THE INVENTION However, the inventors made a large number of prototype discharge lamps for the flickering of the lamp and the performance as an optical device and evaluated the performance as a lamp. In addition, it has been found that the initial performance of the lamp is drastically reduced due to the wear of the electrodes, and the above-mentioned specifications cannot maintain the advantage of the lamp without flicker as an advantage. In addition, regarding the weight percent concentration of potassium contained in the base metal of the tungsten electrode, in the configuration of the discharge lamp, the possibility of becoming a crystal nucleus of the quartz tube is increased, and the effect as described above cannot be obtained. Did not.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to control the spot configuration of a discharge lamp electrode portion and trace elements of a base metal material to prevent electrode wear and prevent flickering. It is an object of the present invention to provide a discharge lamp suitable for obtaining a long life characteristic by preventing a decrease in initial performance of the lamp.

[0009]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is directed to a direct-current discharge lamp having a pair of a tungsten electrode and a pair of an anode and a cathode which are opposed to each other in a discharge vessel made of a non-conductive material. The area of the tip flat portion, which is a spot on the anode, is S1 (mm ² ),
When 1 (A), the discharge lamp was characterized by satisfying 0.1 ≦ S1 / I1 ≦ 0.4.

According to the present invention, the fluctuation of the distance between the electrodes due to the wear of the electrodes is suppressed, the arc spot position is stabilized,
It is possible to provide a long-life discharge lamp free from flicker and initial performance deterioration.

According to another aspect of the present invention, there is provided a closed body having a pair of a tungsten electrode and a pair of an anode and a cathode disposed opposite to each other in a discharge vessel made of a non-conductive material, and arranged to hermetically seal the discharge vessel. The closing body is a discharge lamp made of a material in which the conductive material and the insulating material are functionally inclined in the axial direction, and the area of the tip flat portion, which is a spot on the anode, is S1 (mm). ² ) The current value at the time of lighting is I1 (A)
The discharge lamp was characterized in that 0.1 ≦ S1 / I1 ≦ 0.4.

In the present invention, the advantages of the above-mentioned invention and furthermore, the high-confidentiality and pressure resistance can be ensured by sealing the electrodes with a closing member made of a functionally graded material. It can be suitably used for discharge lamps such as high-pressure mercury lamps and metal halide lamps, and large-sized discharge lamps such as xenon lamps which allow a large current to flow.

Further, by providing a gas adjusting band for adjusting the gas in the discharge space in the closing member, an excessive luminescent substance or impurity is adsorbed and retained, or the released luminous substance released during the lighting is insufficient. Therefore, a long-life discharge lamp can be provided.

Further, the discharge vessel is filled with mercury of 0.12 mg / mm ³ or more, a rare gas and a halogen, and the tube wall load is reduced.
By setting it to 0.5 W / mm ² or more, a discharge lamp with extremely high luminance can be provided.

Further, by controlling the weight concentration of potassium of the tungsten electrode to be 3 ppm or more and 8 ppm or less when the lamp is turned on, it is possible to control the recrystallization temperature of tungsten, control the tungsten grain boundary, and crystallize the quartz tube due to the presence of potassium itself. Thus, the existence probability of potassium as a crystal nucleus that promotes crystallization of the quartz tube can be suppressed to the maximum, and it is possible to provide a long-life discharge lamp that suppresses the graining of the electrode and does not cause flickering and lower initial performance.

The distance between the anode and the cathode is 3 mm.
The volume ratio of the tungsten electrode to the main discharge space as a metal substrate is set to 20% or less, so that the transition to arc discharge at the time of lamp operation can be smoothly performed.
Wear of the tungsten electrode due to spikes during lamp operation is further suppressed, and a long-life discharge lamp free from flicker and initial performance deterioration can be provided.

According to another aspect of the present invention, a reflecting mirror having a paraboloidal or elliptical reflecting surface, or a reflecting mirror comprising the same, and the above-described discharge lamp are integrated with the lamp arc axis and the reflecting mirror optical axis. The lighting device is characterized in that the lighting device is

According to the present invention, a lighting device having no flicker and a long life can be obtained.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described below in order to further clarify the configuration and operation of the present invention described above.

FIG. 1 is an explanatory view of an embodiment of a high-pressure mercury lamp according to the present invention. First, a discharge vessel 11 made of quartz glass
Has a spherical shape or an elliptical spherical shape, in which a cathode 12 and an anode 13 made of tungsten are arranged, and as a result, the electrodes 14 are arranged to face each other. In a discharge space 15 formed in the discharge vessel, an argon gas is sealed at a predetermined pressure as a discharge gas,
As the luminescent metal, mercury and mercury bromide are substantially enclosed. Here, closing bodies 16 are provided at both ends of the discharge vessel 11.
This is a so-called functionally graded material 17 which is functionally graded from a component equivalent to that of the discharge vessel to a conducting metal such as molybdenum or tungsten. The functionally graded material used here is a material obtained by sintering the same material as that of the discharge vessel, silica and molybdenum of a conductive metal. The mixing ratio is changed continuously or stepwise. The side is made non-conductive and the other is made conductive. The silica side of the closing body 16 made of the functionally gradient material is welded to the discharge vessel 11 over at least 2 mm or more over the entire circumference, thereby forming a complete sealing body and a closed system. An external lead wire 18 for electrical conduction is provided on the other side of the closing body, and thereby, a lighting operation power of the lamp is supplied, a gap length is 1.5 mm, and a current value I when the lamp is turned on is 1 to 2.5. Lighted in (A).

FIG. 2 is an explanatory view of an embodiment of an electrode used in a high-pressure mercury lamp according to the present invention. Tungsten electrode 1
The electrode rod 19 of the hole 4 has a hole 2 formed in the functionally graded material 17.
0 is inserted. The hole 20 is a counterbore hole provided in the functionally graded material 17, and a buffer zone 21 having a gas adjusting function made of a hybrid of tungsten and silica is provided in a space formed by the hole 20 and the electrode rod 19. And a closed body 16 in which the electrode and the functionally gradient material are integrated. A spot 19 for receiving an arc is formed at the tip of the anode, and its area S in the embodiment is 0.3 (mm ² ).

By arranging a part of the buffer zone so as to match the temperature of the coldest part when the lamp is turned on, excess luminous substances such as mercury, metal halide, and halogen are effectively moved and held. This also has the effect of supplying the halogen that is insufficient at the time of lighting from the reserved amount.
Further, impurities similar to the constituent gas of the lamp component which are mixed in during the manufacture of the lamp or generated undesirably at the time of lighting can be adsorbed, and the effect can be improved by mixing a substance having a getter function.

In this embodiment, mercury, a rare gas, and a metal halide are substantially sealed as a main luminescent substance, and one inert gas such as helium, neon, argon, krypton, xenon, or radon is used. Alternatively, a plurality can be selected, but may be appropriately selected depending on the type of the discharge lamp.

FIG. 3 shows that the area of the tip flat portion which is a spot on the anode 13 is S1 (mm ² ), and the current value at the time of lighting is I1.
This is an experimental result showing the state of the lamp flicker when the parameter S1 / I1 is changed and the performance of the optical system is reduced after 500 hours when 1 (A) is set.

When the parameter S1 / I1 is 0.1 or less, that is, when the spot area is relatively small with respect to the current, there is almost no flickering of the lamp.
It can be confirmed that the flicker preventing effect introduced in Japanese Patent No. 3487 is high. However, it can be understood that the deterioration of the optical performance of the lamp which occurs during the 500-hour continuous lighting test is so severe that the merits cannot be adopted in a lamp state where the mercury vapor pressure exceeds one hundred and several tens atmospheres.

It is considered that the reason for this is that the spot area at the tip of the anode 13 is so small that the electrodes are worn and the distance between the electrodes is widened. Illumination devices used in liquid crystal projectors, etc. have a homogenizing optical system such as an integrator lens in order to eliminate the deviation in brightness of the projected image projected on the screen, but since this integrator is optimally designed according to the gap length The fact that the distance between the electrodes of the lamp increases in a short time is fatal as a lamp incorporated in an optical device. On the other hand, when the parameter S1 / I1 is 0.5 or more, on the other hand, the optical performance does not decrease, but the spot area is large, and the arc spot position on the anode 13 often shifts to another point, and this causes the flickering of the light. This will make the user uncomfortable. By setting the ratio of the spot area to the current value to be 0.1 ≦ S1 / I1 ≦ 0.4, a discharge lamp having no flicker and having stable optical performance can be formed.

FIG. 4 shows the results of an experiment in which the potassium content of the electrode used in the high-pressure mercury lamp of the present invention, the wear of the electrode, and the life of the lamp were evaluated.

Looking at the state of grain growth of the electrode after 250 hours of continuous lighting of the electrode, the electrode containing 10 ppm or more of potassium also suppressed grain growth, suggesting the correctness of the considerations in JP-A-5-290802. . However, the present high-pressure mercury lamp having a potassium content of 10 ppm or more is very susceptible to clouding, and after 1000 hours, all are in a cloudy state. In the case of potassium having a weight concentration of 2 ppm or less, the electrode was broken after rapid grain growth was confirmed, resulting in no lighting. Lamps at 3 ppm or more and 8 ppm or less have no noticeable abnormality in lamp quality even after 1000 hours, and it can be considered that potassium is a factor causing crystallization of the lamp quartz tube. The weight concentration of potassium contained in the tungsten electrode is 3 ppm or more when the lamp is turned on.
By setting it to pm or less, the existence probability of potassium as a crystal nucleus that promotes crystallization of the quartz tube can be suppressed to the utmost, suppressing the granulation of the electrode, and having a long life and high pressure without flicker and initial performance deterioration. A mercury lamp can be configured.

FIG. 5 shows the evaluation results of the lighting performance of the high-pressure mercury lamp according to the present invention when the volume ratio of the tungsten electrode to the main discharge space as a metal substrate is changed. By setting the volume ratio of the tungsten electrode as the metal substrate to the main discharge space to 20% or less, the lamp can be prepared for transition to an arc by glow discharge for a certain period of time in initial lighting.

Further, by using the discharge lamp of the present invention as a light source, it is possible to obtain a lighting device having no flicker and a long life. FIG. 6 is an explanatory diagram of a lighting device using the discharge lamp of the present invention. A reflecting mirror 23 whose reflecting surface is a paraboloid or an ellipse, or a constituent thereof, and a discharge lamp 24 of the present invention reinforced by a base 26 are provided with a heat-resistant adhesive by combining a lamp arc axis and a reflecting mirror optical axis. 25 are integrated. The lighting device to which the lamp is fixed is explosion-proof glass 2.
7 and plays a role in minimizing damage to equipment in the event of lamp damage. By employing such a structure, a long-life lighting device without flicker and with little reduction in optical performance can be obtained.

The discharge lamp of the present invention and a lighting device using the same can be suitably used for various applications such as a liquid crystal projector, a television, a backlight of OA equipment, and a light source for a semiconductor stepper.

[0032]

[Brief description of the drawings]

FIG. 1 is an explanatory view of an embodiment of a high-pressure mercury lamp according to the present invention.

FIG. 2 is an explanatory view of an embodiment of an electrode used in a high-pressure mercury lamp according to the present invention.

FIG. 3 shows the experimental results of the S1 / I1 parameter of the lamp of the present invention.

FIG. 4 shows the results of an experiment evaluating the potassium content, electrode wear, and lamp life.

FIG. 5 is an experimental result of lighting performance when a volume ratio of a metal substrate is changed.

FIG. 6 shows a lighting device using the discharge lamp of the present invention.

[Explanation of symbols]

 11 Discharge vessel 12 Cathode 13 Anode 14 Electrode 15 Discharge space 16 Closure 17 Functionally graded material 18 External lead wire 19 Electrode rod 20 Hole 21 Buffer band 22 Spot 23 Reflector 24 Arc tube of the present invention 25 Heat resistant adhesive 26 Cap 27 Explosion-proof glass

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01J 61/20 H01J 61/20 U 61/36 61/36 B 61/88 61/88 C (72) Invention Person Shinji Matsubara 2-1-1, Nakajima, Kokurakita-ku, Kitakyushu-shi, Fukuoka Prefecture (72) Inventor Osamu Obayashi 2-1-1, Nakajima, Kokurakita-ku, Kitakyushu, Fukuoka Totoki Co., Ltd. F term (reference) 5C015 JJ06 JJ08 QQ32 RR01 SS03 5C039 HH04 HH06 HH07 5C043 AA03 AA07 CC02 CC05 DD11 EB18

Claims (8)

[Claims] 1. A direct-current discharge lamp having a pair of a tungsten electrode and a pair of an anode and a cathode disposed opposite to each other in a discharge vessel made of a non-conductive material, wherein an area of a tip flat portion as a spot on the anode is S1 (mm). ² ) The current value at the time of lighting is I1
(A) The discharge lamp characterized in that 0.1 ≦ S1 / I1 ≦ 0.4. 2. A discharge vessel made of a non-conductive material, comprising: a pair of tungsten electrodes opposed to each other in a discharge vessel made of a non-conductive material; and a closing body disposed to hermetically seal the discharge vessel. The closing body is a discharge lamp made of a material in which the conductive material and the insulating material are functionally inclined in the axial direction,
The area of the tip flat portion, which is a spot on the anode, is S
1 (mm ² ), when the current value at the time of lighting is I1 (A), 0.1 ≦ S1 / I1
A discharge lamp characterized by ≦ 0.4. 3. The discharge lamp according to claim 2, wherein the closed body is provided with a gas adjustment band for adjusting a gas in a discharge space. 4. The discharge lamp according to claim 1, wherein:
A discharge lamp characterized in that 0.12 mg / mm ³ or more of mercury, a rare gas, and halogen are sealed in the discharge vessel, and a tube wall load is 0.5 W / mm ² or more. 5. The discharge lamp according to claim 1, wherein the tungsten electrode contains potassium in a weight concentration of 3 ppm or more and 8 ppm or less when the lamp is turned on. High pressure mercury lamp. 6. The discharge lamp according to claim 1, wherein:
3. The high-pressure mercury lamp according to claim 1, wherein a distance between the anode and the cathode is within 3 mm. 7. The discharge lamp according to claim 1, wherein the volume ratio of the tungsten electrode to the main discharge space as a metal substrate is not more than 20%. 8. A reflecting mirror having a paraboloidal or elliptical reflecting surface or a reflecting mirror comprising the parabolic surface or an ellipse, and a discharge lamp according to any one of claims 1 to 7, wherein the lamp arc axis and the reflecting mirror optical axis A lighting device, which is also integrated.