JP2003151492A - Short arc type extra-high pressure discharge lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new electrode structure capable of displaying a favorable heat conductive function at the time of starting to light and at the time of constant lighting on a extra-high pressure mercury lamp to light at extremely high mercury steam pressure. SOLUTION: This new electrode structure constitutes its characteristic feature that a pair of sets of electrodes 4, 7, 8 is arranged against each other inside and more than 0.15 mg/mm<3> of mercury is sealed in it, at least one set of the electrodes 4, 7, 8 has electrode rods 41, 7a, 8a and a head end electrode part 42 of a larger diameter than outer diameter of electrode rods 41, 7a, 8a on their head ends and a plurality of heat conductive rod type members 43 fused and integrated with the head end electrode part 42 at a part extend in an extending direction of the electrode rods 41, 7a, 8a and are arranged on an outer surface of the electrode rods 41, 7a, 8a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a short arc type ultra-high pressure discharge lamp which has a mercury vapor pressure of 150 atm or more when lit, and particularly to a liquid crystal display device and a DMD
The present invention relates to a short arc type ultra high pressure discharge lamp used as a backlight of a projector device such as a DLP (digital light processor) using a (digital mirror device).

[0002]

2. Description of the Related Art A projection type projector device is required to illuminate an image uniformly and with sufficient color rendering on a rectangular screen. Therefore, as a light source, mercury or metal halide is used. The enclosed metal halide lamp is used. In addition, such a metal halide lamp has recently been further miniaturized and made into a point light source, and a lamp having an extremely small distance between electrodes has been put into practical use.

Under such a background, recently, a lamp having a mercury vapor pressure which has never been present, for example, 150 atm has been proposed in place of the metal halide lamp. This is to increase the mercury vapor pressure to suppress (narrow down) the spread of the arc and to further improve the light output. Such an ultra-high pressure discharge lamp is disclosed in, for example, Japanese Patent Application Laid-Open Nos. 2-145861 and 6-52830.

Further, there has been proposed an electrode structure in which an electrode portion having a diameter larger than that of the electrode rod is provided at the tip of the electrode rod, and a coil is wound behind the electrode portion. Although this electrode structure is disclosed in FIG. 8, a tip electrode portion 82 having a diameter larger than that of the electrode rod 81 is formed at the tip of the electrode rod 81, and part of the tip electrode portion 82 is melted and integrated behind the tip electrode portion 82. The wound coil member 83 is wound so as to be continuous with the tip electrode portion 82. According to this structure, since the tip electrode portion 82 has a large diameter, the heat capacity is large, so that the problem of evaporation of the electrode constituent material can be satisfactorily solved even if the temperature is raised due to electron collision or the like. Further, since the coil member 83 is formed behind the tip electrode portion 82 so as to be continuous,
The heat generated in the tip electrode portion 82 can be released backward. Such an electrode structure is disclosed in, for example, Japanese Patent No. 28208.
No. 64 and Japanese Patent Laid-Open No. 10-92377.

In this structure, the discharge starting point at the start of discharge is highly likely to occur in the gaps 83a between the wires of the coil member 83 and the rear portions 83b of the coil member 83. Then, the part that has become the discharge starting point locally becomes high in temperature, and gradually heats the adjacent front region. The discharge starting point moves to the front area where the temperature has risen due to this heating. The figure shows the gap portion 83a and the rear portion 83b.
The discharge starting points generated in P1, P2, P3, P4 ...
And the state of moving. If the change in the state of the initial lighting of the lamp is grasped from the discharge phenomenon, the arc discharge is generated in the rear part 83b of the coil member, which is heated the earliest, by the glow discharge generated so as to wrap around the entire coil member immediately after the start of the discharge. It is understood that the starting point of (1) occurs and the starting point moves to the tip with further heating of the tip. In such a state before the movement, the light emitted from the lamp does not serve as a point light source, the light collection efficiency by the reflecting mirror is poor, and as a result, the image becomes dark on the screen. Then, by the movement of the discharge starting point, the discharge starting point finally reaches the leading edge P4 of the tip electrode portion and becomes stable. When the discharge is stably maintained at this cutting edge P8,
It becomes a state suitable for the light source of the projector device.

However, in lighting the discharge lamp,
As described above, it is not always possible to satisfactorily guide the discharge start point to the electrode tip surface, and sometimes discharge may be sustained or stagnated in the coil members indicated by P1, P2, and P3. That is, the discharge starting point is favorably the tip electrode portion 82.
Cannot move to the tip P4 of the coil member 83
In some cases, the unfavorable phenomenon that the toner is fixed in the inside of the chamber or that it is extremely time-consuming to be guided to the tip may occur. Such a phenomenon may cause the lamp to burst or blacken.

The above is the phenomenon at the start of discharge, but during steady lighting, the coil member 83 plays the role of releasing the heat generated at the tip electrode portion 82 backward as described above. However, the short arc type ultra-high pressure discharge lamp used in the projector device has an inner volume of 8 arc tubes.
Despite being as small as 0 mm ³ , the internal pressure during lighting is 15 MPa or more, and the tube wall load value is 0.8 W / mm ²
Since the above-mentioned conditions are extremely severe, it has been found that it is actually difficult to satisfactorily release heat by the coil member shown in FIG. That is, the electrode structure shown in FIG. 8 may be useful in a conventional general discharge lamp having an internal pressure of about 50 atm, but in a discharge lamp under extremely severe conditions like the present invention, it is referred to as heat transfer. In that sense, a new problem arose, which was not necessarily a good structure.

[0008]

DISCLOSURE OF THE INVENTION The problem to be solved by the present invention is a novel high pressure mercury lamp that can be ignited with an extremely high mercury vapor pressure and can exhibit a good heat conduction function at the start of lighting and during steady lighting. To provide a simple electrode structure.

[0009]

In order to solve the above-mentioned problems, the short arc type ultra high pressure discharge lamp of the present invention comprises:
Inside, a pair of electrodes are placed facing each other, and 0.15 mg
/ Mm ³ or more of mercury is enclosed, and at least one of the electrodes has an electrode rod and a tip electrode portion having a diameter larger than the outer diameter of the electrode rod at its tip. Behind, a plurality of heat-conducting rod-shaped members, which are partially melt-integrated with the tip electrode portion, extend along the direction in which the electrode rod extends and are arranged on the outer surface of the electrode rod. Characterize. Furthermore, the invention according to claim 2 is characterized in that, in the above-mentioned claim 1, the plurality of heat-conducting rod-shaped members are arranged twisted around the electrode rod. Furthermore, the invention according to claim 3 is characterized in that, in the above-mentioned claim 1, the plurality of heat-conducting rod-shaped members are twisted to the extent that each heat-conducting rod-shaped member does not make one rotation with respect to the electrode rod. .

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the overall structure of an ultra-high pressure discharge lamp of the present invention (hereinafter also simply referred to as "discharge lamp"). The discharge lamp 1 has a roughly spherical arc tube portion 2 formed by a discharge vessel made of quartz glass. Inside the arc tube portion 2, a pair of electrodes 4 are arranged to face each other. Also, the side tube portion 3 extends from both ends of the arc tube portion 2.
A conductive metal foil 5 usually made of molybdenum is airtightly embedded in these side tube portions 3 by, for example, a pinch seal, and the pair of electrodes 4 is supported by an electrode rod (electrode shaft) 41. The end of the electrode rod 41 is
It is welded to one end of the metal foil 5 and electrically connected. The other end of the metal foil 5 has an external lead 6 protruding outward.
Are welded. The pair of electrodes 4 is the electrode rod 4
It is sometimes referred to as an “electrode” including the above.

The arc tube portion 2 is filled with mercury, a rare gas, and a halogen gas. Mercury is used to obtain a required visible light wavelength, for example, radiated light having a wavelength of 360 to 780 nm, and is contained at 0.15 mg / mm ³ or more. Although this amount of enclosure varies depending on the temperature condition, the vapor pressure becomes extremely high at 150 atmospheric pressure or more during lighting. Also,
By enclosing more mercury, the mercury vapor pressure during lighting is 20
A discharge lamp having a high mercury vapor pressure of 0 atm or more and 300 atm or more can be manufactured, and a light source suitable for a projector device can be realized as the mercury vapor pressure becomes higher. The rare gas, for example, is filled with about 13 kPa of argon gas to improve lighting startability. Halogen is encapsulated in the form of a compound of iodine, bromine, chlorine, etc. with mercury and other metals, and the amount of halogen encapsulated can be selected from the range of 10 ⁻⁶ to 10 ⁻² μmol / mm ^3. Its function is to extend the life by utilizing a halogen cycle.However, in the case of a discharge lamp of the present invention that has an extremely small size and a high internal pressure, it is not possible to damage or lose the discharge vessel by enclosing such a halogen. It is thought that it affects the transparency prevention.

A numerical example of such a discharge lamp is as follows:
For example, the maximum outer diameter of the light emitting portion is 9.5 mm and the distance between the electrodes is 1.
5 mm, arc tube internal volume 75 mm ³ , rated voltage 80 V, rated power 150 W, and AC lighting. In addition, this short arc type ultra-high pressure discharge lamp is built in a miniaturized projector device, etc., and because the overall structure is extremely miniaturized, a high light amount is required, so the heat inside the arc tube section is reduced. Impact is extremely severe,
The tube wall load value is 0.8 to 2.0 W / mm ² , specifically 1.5 W / mm ² . Then, the radiant light having a good color rendering property can be provided by being mounted on a presentation device such as the projector device or the overhead projector described above.

2A and 2B are enlarged views of the electrode 4, FIG. 2A is a side perspective view, and FIG. 2B is a sectional view taken along the line AA 'of FIG. In the figure, the electrode 4 is composed of an electrode rod 41, a tip electrode portion 42 integrally formed at the tip thereof, and a heat conduction rod-shaped member 43 provided behind it. The electrode rod 41 and the tip electrode portion 42 are made of tungsten, the outer diameter of the tip electrode portion 42 is formed to be larger than the outer diameter of the electrode rod 41, and the tip thereof is formed into a curved surface. As described above, since the tip electrode portion 42 has a large diameter, it has a surface area capable of performing sufficient heat radiation by radiation, and thus can sufficiently withstand the heating accompanying the inflow of electrons in the AC cycle. To give a numerical example, the electrode rod 41 has an outer diameter φ
Selected from the range of 0.2 to 1.0 mm, for example φ
0.5 mm, and the tip electrode portion 42 has an outer diameter of φ0.5 to
It is selected from the range of 2.0 mm, for example φ1.2 mm, and the length is selected from the range of 0.5 to 2.0 mm, for example 1.5 mm.

Behind the tip electrode portion 42, the electrode rod 4
A plurality of thermally conductive rod-shaped members 43 extending along the electrode rod direction are disposed on the outer surface of the electrode 1. This rod-shaped member 43 is
The tip electrode portion 42 is made of tungsten and is fused and integrated at the tip thereof. The action of the rod-shaped member 43 is as follows at the start of lighting the discharge lamp and at the time of steady lighting. At the start of lighting, first, the discharge starting point is formed in the gap 43a formed between the rod-shaped members 43 or in the rear end portion 43b of the rod-shaped member 43. Although the discharge starting point is locally in a high temperature state, the high temperature causes the rod-shaped member 43
Heat is satisfactorily conducted to the tip electrode portion 42 via the, and the temperature of the tip electrode portion 43 is thereby raised, so that the discharge starting point is favorably moved to that position, and a stable arc discharge state can be achieved. . Further, in the steady lighting state, the electrode tip temperature is extremely high, about 3000 ° C., but the high temperature can be satisfactorily conducted and radiated backward from the tip electrode portion 42 via the rod-shaped member 43. .

As described above, the direction of heat conduction is different at the start of lighting and at the time of steady lighting, but in each case, compared with the conventional electrode structure shown in FIG. 8, each rod-shaped member 43 is shorter as a path. Since heat can be conducted at a distance, its efficiency is extremely high, in other words, heat conduction with little loss can be achieved. That is, in the electrode structure shown in FIG. 8, heat is conducted to the adjacent rod-shaped members by rotating around the electrode rod once over the outer surfaces of the rod-shaped members, or transmitted inside the rod-shaped members. However, since it is transmitted while rotating, its conduction efficiency is not necessarily high.

For the rod-shaped member 43, to give numerical examples, the rod-shaped member 43 is selected from an outer diameter range of 0.1 to 0.5 mm.
The length in the electrode rod direction is selected from the range of 1.0 to 10.0 mm, and is, for example, 2.0 mm. Six rod-shaped members 43 may be densely arranged on the outer surface of the electrode rod 41 so that they are in contact with each other, but a gap may be provided between the rod-shaped members 41.

The sectional shape of the rod-shaped member 43 is not limited to a circular shape, but an elliptical shape as shown in FIG. 3A, a semi-circular shape as shown in FIG. Various shapes such as a square shape as shown in FIG. 4 and a triangular shape as shown in FIG. However, these shapes are not simply listed as embodiments,
It can be selected depending on which of the function at the time of starting the lighting and the function at the time of steady lighting is more important. That is, as shown in FIG. 2, when each rod-shaped member 43 has a circular shape and is in point contact with the electrode rod 41, the heat conduction efficiency between the rod-shaped member 43 and the electrode rod 41 is low, that is, the rod-shaped member 43 is Thermal conduction mainly functions with the tip electrode portion 42. In other words, when more importance is attached to the heat conduction at the start of lighting, the structure in which the heat generated in the rod-shaped member 43 is guided to the tip electrode portion 42 without being dissipated by the electrode rod 41, which is in point contact with the electrode rod 41, that is, Figure 2
The circular cross-section shown in (2) is suitable.

When each rod-shaped member 43 comes into surface contact with the electrode rod 41, the heat conduction efficiency between each rod-shaped member 43 and the electrode rod 41 becomes relatively high. That is, when more importance is attached to heat conduction during steady lighting, a structure in which the heat generated in the tip electrode part 42 is in surface contact with the electrode rod 41 in order to radiate the heat using both the rod member 42 and the electrode rod 41, that is, The semicircular shape shown in FIG. 3B, the rectangular shape shown in FIG. 3C, the triangular shape in which the surfaces shown in FIG. When the rod-shaped member 43 shown in FIG. 3A has an elliptical cross section, the contact with the electrode rod 41 is larger than that of the circular cross-section shown in FIG. 2, but FIGS. The contact with the electrode rod 41 is smaller than that of the structure shown in FIG.

FIG. 4 shows another embodiment of the short arc type ultra high pressure discharge lamp of the present invention. The heat conductive rod-shaped member 44 in this embodiment is not a linear member as in the structure shown in FIG. 2, but is arranged twisted around the electrode rod 41, and has a rope-shaped form as a whole. Form. The advantage of this mode is that the electrode rod 41 can be formed by twisting the rod member 43.
It is because the adhesion of the electrode structure to the electrode structure is enhanced, so that the manufacturing of the electrode structure itself is simplified. In addition, since the adhesion between the rod-shaped members 43 is also increased, there is an advantage that the mixing of impurities into the gap between the rod-shaped members 43 can be reduced. Further, it is possible to prevent the rod-shaped member 43 from spreading due to high temperature during the lighting of the lamp. The rod-shaped member 44 is characterized in that it does not make one revolution around the electrode rod 41. This is because when the rod-shaped member 44 makes one or more rotations around the electrode rod 41, heat conduction is performed between the outer surfaces of the rod-shaped member similarly to the conventional structure shown in FIG.
Alternatively, even if the conduction takes place through the inside of the rod-shaped member, the path becomes long and the conduction efficiency deteriorates. To give a numerical example, the rod-shaped member 44 is, for example, 1/10 to 1/1 rotation, more preferably 1/6 to 1/2 rotation, in a range that does not make one rotation around the electrode rod 41. To do.

FIG. 5 shows still another embodiment of the short arc type ultra high pressure discharge lamp of the present invention. The heat conductive rod-shaped member in this embodiment is not only provided on the outer peripheral surface of the electrode rod 41 as in the structure shown in FIGS. 2 and 3, but the rod-shaped member 43 is twisted on the outer peripheral surface of the electrode rod 41. The rod-shaped member 45 is twisted with respect to the electrode rod 41 and is arranged on the outer peripheral surface thereof. The advantage of this form is that FIG. 2 and FIG.
Since the number of rod-shaped members is larger than that of the electrode structure shown in (1), the amount of heat conduction can be further increased. That is, the structure can be more suitable for a high power type discharge lamp.
In addition, since the number of rod-shaped members 45 is large, there are more places where the discharge starting points should be formed at the time of starting the discharge, and it is possible to stochastically reduce the occurrence of certain discharge starting points and the occurrence of concentration at certain points. It is possible to prevent the discharge lamp from concentrating on a specific point and reduce the probability of the discharge lamp bursting or blackening.

In the figure, the twisted rod-shaped member 45 is provided on the outer peripheral surface of the twisted rod-shaped member 43, but the present invention is not limited to this form, and the outer periphery of the linear rod-shaped member is not limited to this. Similarly, a linear rod-shaped member may be arranged on the surface, and a twisted rod-shaped member may be arranged on the outer peripheral surface of the linear rod-shaped member. To give a numerical example, by arranging the outer rod-shaped member 45 closely on the outer surface of the inner rod-shaped member 43 without a gap, the outer rod-shaped member 45
Is 12 and the inner rod-shaped member 43 is 6. Further, the outer diameter value and the length of the outer bar-shaped member 45 can be similarly applied to the above-mentioned numerical values. Such an electrode structure can be effectively applied to a high power type, particularly a discharge lamp rated at 80 W or more.

More preferably, the electrode rod has 20 to 100
It is doped with ppm by weight of potassium. The reason for this is that the inclusion of potassium increases the strength of the electrode rod, and in general, core wire breakage can be prevented or reduced. It has been confirmed that, if potassium is not doped, the electrode rod will break the core wire even with a slight impact, whereas doping with potassium in the above numerical range dramatically improves the core wire breakage. It was In particular, it is useful to increase the strength by doping potassium in the electrode structure of the present invention. This is because the rod-shaped member is attached to the electrode tip, the weight of the electrode tip is large, and the manufacturing process of attaching the rod-shaped member to the electrode rod or the process of twisting the rod-shaped member reduces the strength of the electrode rod. This is because it is included.

When the concentration of potassium is 20 ppm or less, the effect of strengthening the electrode rod cannot be exerted, and when it exceeds 100 ppm, potassium released into the discharge space during lamp operation hinders the halogen cycle. This causes blackening and devitrification. In addition, the electrode rod which is the target of the concentration of potassium means a portion which protrudes into the discharge space and does not include the tip electrode portion. Furthermore, as a more preferable form, it is preferable to locally dope the portion of the electrode rod where the rod-shaped member is disposed on the peripheral surface with potassium. It is preferable to locally dope potassium when it is necessary to increase the mechanical strength of the portion where the rod-shaped member is arranged.

FIG. 6 shows another embodiment of the short arc type ultra high pressure discharge lamp of the present invention. While this discharge lamp is an AC lighting type, the discharge lamp shown in FIG.
The difference is that it is a DC lighting type. That is, in the arc tube portion 2, cathodes 7 (cathode rods 7 having different shapes and sizes) are formed.
a) and an anode 8 (anode rod 8a) are different, and the others are the same as those in FIG. 1, and the same reference numerals indicate the same components, and therefore the description thereof will be omitted. In this discharge lamp, the rod-shaped member 4 is attached to each of the electrode rods 7a and 8a of the cathode 7 and the anode 8.
3 is formed. As shown in the figure, the anode 8 generally forms an electrode head having a diameter larger than that of the electrode rod 8a, and this electrode head has a tip cone portion, a central cylinder portion, and a rear end cone portion. The rod-shaped member 43 is fused and integrated with the rear end cone portion.

The rod-shaped member 43 does not need to be formed on both the cathode 7 and the anode 8, and may be formed on either one. When the function of the rod-shaped member 43 at the start of discharge is expected more, the rod-shaped member 4 is attached to the cathode 7.
3 is suitable, and when it is desired to expect the function of the rod-shaped member 43 during steady lighting, the rod-shaped member 43 is preferably provided on the anode 8. This is because at the start of discharge, electrons are radiated from the cathode 7, and it is necessary to move the discharge starting point to the tip electrode portion. Further, at the time of steady lighting, the anode 8 does not emit electrons. This is because it is liable to be heated to a high temperature due to the collision with the above, and this requires heat conduction from the tip electrode portion of the anode.

In addition, in the DC lighting type discharge lamp, as shown in FIG.
It goes without saying that the electrode structures shown in FIGS. 4 and 5 can be applied.

Next, a method of manufacturing the electrode structure shown in FIG. 2 will be described with reference to FIG. (A). First, a rod-shaped member rod 43 'to be a rod-shaped member is attached to the wire 71 on the outer peripheral surface of the electrode rod 41' to be an electrode rod.
Temporarily fix it by, for example. The method of temporary fixing is not limited to the method of binding with the wire 71, and it is also possible to put it in a mold, for example. (B). Next, using the gas burner 72, the rod-shaped member rod 43 '
Melt and integrate one end of. Thereby, the tip electrode portion 4
2 is formed. Since the tip electrode portion 42 is mainly formed by melting the rod-shaped member rod 43 ', the rod-shaped member rod 43' is formed.
It is preferable to use a material having a low potassium content. The gas burner 72 is for melting at a high temperature of 3500 ° C., for example. (C). Next, the rod-shaped electrode rod 43 'is cut into a desired length by a laser beam machine, for example. At this time, the electrode rod 41 'is not cut. As a result, the rod-shaped member 43 is formed. (D). Next, the electrode rod 41 'is cut into a desired length by a laser beam machine, for example. This allows
The electrode rod 41 is formed. The length of the electrode rod 41 includes the welded portion with the molybdenum foil, so that it must be longer than the portion protruding into the discharge space.

Further, in the manufacturing method of the structure shown in FIG. 4, that is, the structure in which the rod member is twisted with respect to the electrode rod,
After (a), a step of twisting the rod-shaped member rod 43 'with respect to the electrode rod 41' is added. In this case, wire 7
In some cases, temporary fixing by 1 becomes unnecessary. Also, FIG.
In the manufacturing method of the structure shown in FIG. 7, that is, the structure in which the rod-shaped member is formed in two steps with respect to the electrode rod, after the rod-shaped member rod 43 ′ is further arranged around the periphery of FIG. A step of twisting the arranged rod-shaped member rod 43 'is added.

Finally, a numerical example of the short arc type discharge lamp according to the present invention will be introduced. Outer diameter of side pipe part: 6.
0mm Total length of lamp: 65.0mm Length of side tube: 25.0mm Inner volume of arc tube: 0.08cc Distance between electrodes: 2.0mm Rated lighting voltage: 200w Rated lighting current: 2.5A Enclosed mercury amount: 0. 15 mg / mm ³ Noble gas: Argon at 100 Torr

As described above, in the short arc type ultra-high pressure mercury lamp of the present invention, at least one electrode has a tip electrode portion at the tip of the electrode rod, and the tip end electrode portion is melted and integrated behind the tip electrode portion. Since the plural heat transfer rod-shaped members are formed and extended in the extending direction of the electrode rod, the following operational effects are obtained. That is, at the start of lighting of the discharge lamp, first, the discharge starting point is formed on the rod-shaped member, but since this discharge starting point is satisfactorily guided to the tip electrode portion by the high thermal conductivity of the rod-shaped member, a short time is required. Further, it is possible to accurately achieve a stable transition to the arc discharge state at the start of discharge. Further, in the steady lighting state, high temperature can be satisfactorily conducted and radiated from the tip electrode portion via the rod-shaped member.

[Brief description of drawings]

FIG. 1 shows an overall configuration diagram of an ultra-high pressure discharge lamp of the present invention.

FIG. 2 shows an enlarged view of electrodes of the ultra-high pressure discharge lamp of the present invention.

FIG. 3 shows an example of a rod-shaped member provided on an electrode of the ultra-high pressure discharge lamp of the present invention.

FIG. 4 shows another embodiment of the electrode structure of the ultra-high pressure discharge lamp of the present invention.

FIG. 5 shows another embodiment of the electrode structure of the ultra-high pressure discharge lamp of the present invention.

FIG. 6 shows another embodiment of the ultra-high pressure discharge lamp of the present invention.

FIG. 7 shows a method for manufacturing the electrode structure of the ultra-high pressure discharge lamp of the present invention.

FIG. 8 shows a conventional ultra high pressure discharge lamp.

[Explanation of symbols]

1 discharge lamp 2 arc tube 3 side pipe 4 electrodes 5 metal foil 6 External lead 7 cathode 8 anode 41 electrode rod 42 Tip electrode part 43 bar 44 Rod member 45 bar

Claims (4)

[Claims] 1. A pair of electrodes are arranged to face each other, and
In a short arc type ultra high pressure discharge lamp in which 0.15 mg / mm ³ or more of mercury is filled, at least one electrode has an electrode rod and a tip electrode portion having a diameter larger than the outer diameter of the electrode rod at its tip. Behind the tip electrode part, a plurality of heat-conducting rod-like members, which are partially melt-integrated with the tip electrode part, extend along the direction in which the electrode rod extends, and on the outer surface of the electrode rod. A short arc type super high pressure discharge lamp characterized by being arranged. 2. The plurality of heat conduction rod-shaped members are arranged twisted around the electrode rod.
Short arc type ultra high pressure discharge lamp described in. 3. The short arc type ultra-high pressure discharge according to claim 1, wherein the plurality of heat conducting rod-shaped members are twisted to the extent that each heat conducting rod-shaped member does not make one revolution with respect to the electrode rod. lamp. 4. The short arc type ultra high pressure discharge lamp according to claim 1, wherein the electrode rod provided with the heat conducting rod-shaped member is doped with 20 to 100 ppm by weight of potassium.