KR20110006605A - Short arc type discharge lamp - Google Patents

Abstract

PURPOSE: A short arc type discharge lamp is provided to prevent a deformation projection phenomenon by interposing a buffering material between a leading end central part and an annular part adjacent to the central part. CONSTITUTION: A pair of an anode(31) and a cathode are arranged to face each other within an arc tube. A buffering material(36) is interposed between the leading end central part of the anode and the adjacent annular part. An insertion part is inserted into an opening formed in the anode leading end side by interposing the buffering material into the opening. The buffering material is made of a metal film. The buffering material is rolled to an insertion body(35).

Description

Short arc type discharge lamp {SHORT ARC TYPE DISCHARGE LAMP}

TECHNICAL FIELD This invention relates to a short arc type discharge lamp. Specifically, It is related with the short arc type discharge lamp applied to the light source for exposures, such as the manufacturing field of a semiconductor and a liquid crystal, and the light source for backlight of a projector.

The short arc type discharge lamp is used as a light source for an exposure apparatus or a backlight of a projector by combining with an optical system because the distal end distance of the pair of electrodes disposed in the light emitting tube is short and close to the point light source.

Japanese Patent Laid-Open No. 10-188890 discloses a conventional short arc type discharge lamp.

The conventional short arc type discharge lamp is shown in FIG. 7, The light emitting tube 10 of the short arc type discharge lamp 1 has the light emitting part 11 formed in the substantially spherical shape centered in the center, and The sealing part 12 is provided. In the light emitting tube 10, a cathode 21 made of tungsten or the like and an anode 31 are disposed to face each other, and a light emitting material such as mercury and xenon is enclosed in the light emitting space S therein.

Electrode shafts 22 and 32 provided after the cathode 21 and anode 31 are sealed by the sealing portion 12 via a metal foil (not shown).

In recent years, however, in the short arc type discharge lamp used in the manufacturing process of a semiconductor or a liquid crystal panel, as shown in Japanese Patent Laid-Open No. 2000-181075, the lamp is always lit with a constant power to save power. The lighting method is to turn on (normal lighting) at rated power only during exposure, and to turn on (standby lighting) at a minimum power smaller than the rated power when waiting for substrate movement, etc. (hereinafter referred to as full standby lighting). Is adopted.

For example, it is repeated to light 0.1-10 second at rated power at the time of exposure, and to light 0.1-100 second at standby power smaller than rated power at the time of standby.

By the way, when the lamp is turned on or off, or when the input power is changed at the time of full standby lighting, the heat flux flowing from the arc to the anode changes, so that the anode temperature changes, and the anode has an internal stress. Occurs.

At this time, as shown to FIG.8 (A), (B), the center part 50 of the anode front end surface which faces an arc is the part with the largest temperature change, and also thermal expansion becomes large. In contrast, the annular portion 51 around the central portion 50 has a smaller temperature change than the central portion 50, and its thermal expansion is also smaller.

Therefore, the center part 50 receives compressive stress from the peripheral annular part 51 by such thermal expansion, and as a result, it deform | transforms so that it may protrude from a front end surface.

Such projection remains even after the temperature at the tip of the anode is stabilized at the rated lighting time, without returning to the original shape completely. In addition, in the case of the full standby lighting in particular, such deformation occurs repeatedly, and the protrusions accumulate and enlarge.

Then, the discharge concentrates on the enlarged protrusion, the protrusion abnormally overheats, the electrode material evaporates, adheres to the inner wall of the light emitting tube, and the inner wall of the light emitting tube is blackened, causing a rapid decrease in illuminance.

(Patent Document 1) Japanese Patent Application Laid-Open No. 10-188890 (Patent Document 2) Japanese Patent Application Laid-Open No. 2000-181075

The problem to be solved by the present invention is to solve the problems of the prior art, in particular, in a short arc discharge lamp employing a full standby lighting method, to reduce the thermal stress generated at the tip of the anode, the center portion of the tip of the anode It is an object of the present invention to provide a short arc type discharge lamp having an anode structure capable of preventing this deformation and preventing blackening.

In order to solve the said subject, the short arc type discharge lamp which concerns on this invention interposed the buffer material which consists of metal whose yield stress is smaller than the anode material between the center part of the tip of the anode, and the peripheral annular part of the anode. .

The tip end portion is formed of an insert separate from the anode, and the insert is inserted through the buffer member in an opening formed in the anode tip surface.

In addition, the cushioning material is made of a metal foil, and is wound around the insert.

The insert is composed of a ring-shaped first insert and a second insert inserted through the cushioning material through the first insert.

The inner peripheral surface of the ring-shaped first insert is characterized in that there is a crack extending radially on the tip surface of the anode.

The ring-shaped first insert is divided into a plurality of pieces.

The opening is a through hole penetrating to the rear end of the anode, the insert is made of an electrode shaft, the electrode shaft is inserted into the through hole, and the front end thereof faces the front end surface of the electrode.

An annular opening is formed in the distal end surface of the anode to form the distal end portion and the peripheral annular portion, and a buffer material made of sintered metal is interposed in the annular opening.

Moreover, the relief groove | channel of the said metal foil is formed in at least one of the inner surface of the said opening, or the outer surface of the said insert. It is characterized by the above-mentioned.

Moreover, the said relief groove is formed in the circumferential direction, It is characterized by the above-mentioned.

Moreover, the said relief groove is formed in the axial direction, It is characterized by the above-mentioned.

According to the short arc type discharge lamp of the present invention, a buffer material made of a metal having a lower yield stress than that of the anode material is interposed between the tip center portion of the anode and the peripheral annular portion thereof, and therefore, particularly at the time of full standby lighting. Even if the temperature is changed, the thermal deformation of the tip center portion is absorbed by the buffer material, so that the phenomenon of deformation and protrusion does not occur. As a result, the tip center portion is not abnormally overheated and blackening of the light emitting tube does not occur.

Further, even when the cushioning material is plastically deformed by thermal expansion, since a relief groove is formed in at least one of the insert and the opening, the expanded portion of the cushioning material penetrates into the relief groove and protrudes from the tip end surface of the anode. Since this part is not abnormally overheated, blackening of the light emitting tube does not occur.

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing of the principal part of the front-end | tip of the anode of 1st Example of the short arc type discharge lamp which concerns on this invention.
2 is a sectional view of principal parts of a second embodiment;
3 is a sectional view of principal parts of a third embodiment;
4 is a sectional view of principal parts of a fourth embodiment;
5 is a sectional view of principal parts of a fifth embodiment;
6 is a sectional view of principal parts of a sixth embodiment;
7 is a general view of the prior art.
8 is an explanatory diagram of the main parts of FIG. 7;
9 is a sectional view of principal parts of the positive electrode of the seventh embodiment;
10 is an enlarged cross-sectional view of the distal end of FIG. 9;
11 is a sectional view of principal parts of the eighth embodiment;
12 is a sectional view of principal parts of a ninth embodiment;
13 is a graph showing the effect of the present invention

1: is sectional drawing of 1st Example, (A) is insertion sectional drawing, (B) is explanatory drawing of an insertion process.

In the figure, an opening 34 opening in the tip end surface is formed in the center portion of the tip end face 33 of the anode 31. In addition to the anode 31, an insert 35 made of the same material as the anode is molded into a shape matching the opening 34, and the insert 35 is formed of the shock absorbing material 36. Is inserted and inserted into the opening 34 by means of injection or the like.

Specifically, an insert 35 made of the same tungsten is inserted into the opening 34 of the tip face of the anode 31 made of tungsten, and the opening 34 and the insert 35 are the insert. In order to make it easy to press-fit 35, it is good to become a taper shape with a slightly thin tip.

The shock absorbing material 36 is made of a metal material having a lower yield stress at the same temperature than the anode 31 and the insert 35, and specifically, made of tantalum, molybdenum, niobium, rhenium, or the like. In this embodiment, the metal foil is wound around the outer periphery of the insert 35 and inserted into the opening 34 together with the insert 35.

By doing so, when the insert 35 constituting the tip center portion of the anode 31 is thermally expanded, the cushioning material 36 sandwiched between the insert 35 and the annular portion around the periphery causes high temperature creep deformation. It becomes the form which absorbs and alleviates the thermal expansion content of the insert 35, and does not receive the compressive stress by a peripheral annular part.

As a result, the insert 35 constituting the tip center portion is not deformed, and no local protrusion is formed.

Therefore, even when the lamp is turned on or off or the full standby lighting for a long time, local projection of the center portion of the anode tip can be prevented, and evaporation of the anode material and the resulting decrease in roughness can be suppressed.

2 is a cross-sectional view of the second embodiment, (A) is an insertion cross-sectional view, (B) is an explanatory diagram of an insertion step.

In this embodiment, the insert 35 consists of a first insert 37 and a second insert 38. The through hole 40 is formed in the center of the first insert 37 so as to form a ring shape as a whole. In the through hole 40, the second insert 38 is press-fitted through the buffer material 41. It is inserted.

The insert 35 thus formed is press-fitted into the opening 34 formed in the front end face 33 of the anode 31 in a state where the buffer member 42 is provided on the outer circumference.

The opening 34 of the anode 31 and the through hole 40 of the first insert 37 in this second embodiment also have a slightly tapered shape as in the first embodiment. In this embodiment, the shock absorbing materials 41 and 42 are made of metal foil, and are wound around the second insert 38 and the first insert 37, respectively.

According to this embodiment, since the two shock absorbing materials 41 and 42 are sandwiched between the tip center portion of the anode 31 and the peripheral annular portion thereof, the absorbing action against the thermal expansion of the insert 35 constituting the tip center portion is absorbed. It functions more than this.

3 is a sectional view of the third embodiment, (A) is an insertion sectional view, and (B) is a bottom view of the main portion thereof.

In the figure, a plurality of cracks 43 are formed on the central through-hole side of the first insert 37 constituting the insert 35 and are exposed to the tip end surface of the anode 31 and extend radially in the radial direction. It is.

Such a crack 43 is formed by using a simulated light bulb to place a cathode facing the anode 31 and discharging the cathode under predetermined conditions between the two electrodes. The discharge conditions are as follows, for example.

In the argon atmosphere (1 atm), the anode was thermally shocked by discharging for 10 seconds for 1 second at 200 A for 1 second (0.5 Hz) for 10 seconds and causing a crack (crack).

By the above discharge, the inner second insert 38 becomes higher in temperature and expands outward. At this time, since the temperature rise of the outer side of the first insert 37 is larger than that of the second insert 38, the amount of thermal expansion is not large. Therefore, the first insert 37, which is the outer member, is subjected to tensile stress in the circumferential direction, and when the stress reaches a predetermined size, the first insert 37 cannot withstand the stress and cracks occur from the inner circumference to the outer circumference. .

The crack 43 formed in this way is about 70 micrometers in the clearance gap, for example.

According to this embodiment, when the tip central portion of the anode 31 is rapidly heated, in addition to the absorption action of the thermal stress by the shock absorbing materials 41 and 42, the thermal stress in the circumferential direction can be alleviated. Deformation can be more reliably avoided.

In addition, since the cracks 43 are formed to extend in the radial direction, they do not interfere with the heat transfer in the radial direction at the tip of the anode 31.

4 is a sectional view of the fourth embodiment, (A) is an insertion sectional view, and (B) is a bottom view of the main portion thereof.

In this embodiment, the first insert 37 is divided into a plurality of blocks 37A in the radial direction (four in the example in the drawing), and these are combined to form the first insert 37. Here, some space | interval 44 is formed in the mutually adjacent part of each division block 37A, and the clearance 44 is corresponded to the crack 43 in the said 3rd Example.

According to this embodiment, the troublesome work of creating the crack 43 is omitted, and the gap extending radially in the radial direction can be surely formed.

5 is a cross-sectional view of the fifth embodiment, wherein the opening formed in the leading end center portion of the anode 31 is a through hole 45 penetrating to the rear end of the anode 31, and the leading end portion is formed in a substantially tapered shape. Then, in the state where the shock absorbing material 36 made of metal foil is wound around the tapered tip end portion 32A of the electrode shaft 32, the tip end portion 32A is inserted from the rear end side of the through hole 45. ), And the front end face thereof faces the front end face 33 of the electrode 31.

According to this embodiment, since the insert 35 is made up of the electrode shaft 32, there is no worry that the insert is detached from the anode 31 and the insertion of the electrode shaft 32 into the electrode 31 is achieved. In one step, the tip insert is also inserted at the same time, thereby reducing the number of steps.

In addition, in the Example of FIGS. 1-5, although the shock absorbing materials 36, 41, 42 were demonstrated as metal foil, it is not limited to metal foil, The thing which made tantalum powder etc. into paste form 35 (FIG. 1), after applying to the first insert 37 and the second insert 38 (FIGS. 2-4) or the electrode shaft 32 (FIG. 6), and inserting this into the electrode 32, A buffer material may be formed by sintering in a vacuum container.

FIG. 6: is a 6th Example, (A) is insertion sectional drawing, (B) is the bottom view.

In this embodiment, an annular opening 46 is formed in the tip surface 33 of the anode 32, and the tip center portion and the peripheral annular portion are formed in the anode tip surface. In the annular opening 46, a buffer material of powder is filled, and the buffer material 47 is formed between the tip center portion and the peripheral annular portion by sintering in vacuum.

According to this embodiment, the insert of the separate body inserted into the distal end portion of the anode 31 is not molded on purpose, and therefore there is no fear of detachment thereof.

In order to compare this invention and the conventional anode, the lighting test with respect to the illumination intensity retention based on Example 1 was done.

The lamp used for the experiment has the amount of 30 mg / cc of encapsulated mercury and the size of the positive electrode having an outer diameter of 25 mm, a total length of 40 mm, and a front end surface of 10 mm.

The diameter D of the opening 34 formed in this lamp was changed and experimented.

Lighting conditions and evaluation

The lighting cycle of 5 sec at 50 kV and 50 sec at 3 kW was repeated, and the height of tip part: tip protrusion amount (mm) in the anode tip surface after lighting for 500 hours was evaluated.

Moreover, illuminance retention ratio computed the illumination intensity retention after lighting for 500 hours on the basis of the ultraviolet illuminance of wavelength 365nm (i line) at the time of lighting start in the same lighting conditions.

In the lamp of the present invention, the diameters of the openings formed at the tips of the anodes of the lamps were evaluated to be 3 mm, 6 mm, and 8 mm.

Table 1 shows the results of these experiments.

As can be seen from Table 1, the amount of protrusion of the tip of the anode after lighting for 500 hours was 0.94 mm in the conventional electrode, and decreased to 0.41 to 0.72 mm in the electrode of the present invention. Significant improvements were made from 89% to 86%.

As described above, the short arc discharge lamp according to the present invention interposed a buffer material made of a metal having a lower yield stress than the anode material between the center portion of the positive electrode and the peripheral annular portion thereof. Even when the lighting method is adopted, the center portion of the tip of the anode is heated and does not protrude locally, but it is possible to suppress the decrease in illuminance caused by evaporation of the anode material as the center portion protrudes and the blackening of the light emitting tube resulting therefrom. Effect.

Next, a seventh embodiment of the present invention will be described. This example is an application example in the case where the shock absorbing material is a metal foil.

9 is a cross-sectional view of the seventh embodiment, (A) is an insertion cross-sectional view, (B) is an explanatory diagram of an insertion step.

In the figure, the opening 34 which opens in the front end surface 33 is formed in the center part of the front end surface 33 of the anode 31. As shown in FIG. In addition to the anode 31, an insert 35 made of the same material as the anode is molded into a shape matching the opening 34, and the insert 35 is formed of the shock absorbing material 36. Is inserted and inserted into the opening 34 by means of injection or the like.

Specifically, an insert 35 made of the same tungsten is inserted into the opening 34 of the tip face of the anode 31 made of tungsten, and the opening 34 and the insert 35 are the insert. In order to press-fit (35) easily, it is good to become a taper shape with a slightly thin tip.

The shock absorbing material 36 is made of a metal material having a lower yield stress at the same temperature than the anode 31 and the insert 35, and specifically, made of tantalum, molybdenum, niobium, rhenium, or the like. In this embodiment, the metal foil is wound around the outer periphery of the insert 35 and inserted into the opening 34 together with the insert 35.

And the relief groove 60 of the buffer material extended in the circumferential direction is carved in the outer peripheral surface of the insert 35. As shown in FIG. The relief groove 60 may be a single circumferential groove one by one or a spiral groove enclosed in a spiral shape.

By doing so, when the insert 35 constituting the tip center portion of the anode 31 is thermally expanded, the cushioning material 36 sandwiched between the insert 35 and the annular portion around the periphery causes high temperature creep deformation. It becomes the form which absorbs and alleviates the thermal expansion content of the insert 35, and does not receive the compressive stress by the annular part 33a of the periphery of the said opening 3. As shown in FIG.

As a result, the insert 35 constituting the tip center portion does not deform, and no local protrusion is formed.

In addition, as shown in FIG. 10, even when the shock absorbing material 36 tries to plastically deform by thermal expansion, the expanded portion penetrates into and is absorbed into the relief groove 60 of the outer circumferential surface of the insert 35, thereby expanding in the axial direction. Is relaxed, and the tip does not protrude from the tip surface 33 of the anode 31.

Therefore, even if the lamp is turned on or off, or the full standby lighting for a long time, local projection of the center portion of the anode tip is prevented, and the evaporation of the anode material is suppressed, and the projection from the anode tip surface of the buffer material is also prevented, and the evaporation of the buffer material is prevented. Since it can suppress, the fall of the roughness accompanying evaporation of these materials can be suppressed largely.

In the above embodiment, although the relief groove 60 is provided in the insert 35, the relief groove 61 is inscribed in the inner surface of the opening 34 of the anode 31 in FIG.

Also in this embodiment, the relief groove 61 functions similarly to the relief groove 60 of the first embodiment, absorbs thermal expansion of the shock absorbing material 36 from the relief groove 61, This is to prevent protrusion from the tip surface 33.

In the embodiment shown in FIGS. 1 to 3 above, the relief grooves 60 and 61 of the cushioning material are formed in the circumferential direction. In the embodiment shown in FIG. 12, the reliefs extending in the axial direction on the outer peripheral surface of the insert 35 are formed. The groove 62 is engraved.

Also in this example, the thermal expansion component of the shock absorbing material 36 penetrates into the relief groove 42 to be absorbed and does not protrude from the front end surface 33 of the anode 31. The same applies to the case of (60, 61).

Of course, also in this case, the relief groove 62 may be formed not on the insert 35 side but on the opening 34 side.

The relief grooves 60, 61, 62 are described as being engraved on the outer surface of the insert 35 or the inner surface of the opening 34 of the anode 31, but may be formed on both of them.

In the molding of the relief groove, in the case of the relief groove of the outer surface of the insert 35, for example, the relief groove can be formed by cutting or laser processing by a lathe, and the opening of the anode 31. In the case of the relief groove of the inner surface of 34, it can be formed by cutting by a lathe etc., for example.

The cross-sectional shape of the relief groove may be any one of a triangle, a trapezoid, a circle, or a combination thereof.

In order to compare the positive electrode of the present invention with the conventional positive electrode and the positive electrode of the comparative example, the lighting test for the amount of tip protrusion and roughness retention of the positive electrode based on Example 1 as the positive electrode of the present invention, and the positive electrode according to the prior art and the comparative example Done.

The lamp used for the experiment was a sealed mercury amount of 30 mg / cc, and the positive electrode had a diameter of 25 mm, a total length of 40 mm, and a diameter of a front end surface of 8 mm.

And the opening 34 formed in the anode of this invention and the anode of a prior application (comparative example) is diameter 7mm, and the length of the insert 35 is 10 mm.

·anode

Positive electrode A of the present invention: An electrode in which a spiral groove 40 having a depth of 75 µm and a pitch of 200 µm is formed on an outer surface of the insert 35. (See Fig. 9).

Anode B of Comparative Example: An electrode without a relief groove in the insert 35 or the opening 34. (See FIG. 1).

Anode C of the prior art: An electrode having an integrated shape without an insert. (See Fig. 8).

Lighting conditions and evaluation

The lighting cycle of 6 sec at 26 kW and 26 sec at 2 kW of input power was repeated, and the height of tip part: tip protrusion amount (mm) in the anode tip surface after lighting for 500 hours was evaluated.

Moreover, illuminance retention ratio computed the illumination intensity retention after lighting for 500 hours on the basis of the ultraviolet illuminance of wavelength 365nm (i line) at the time of lighting start in the same lighting conditions.

Table 2 below and the roughness retention rate of the above experimental results are shown in FIG. 13.

As can be seen from Table 2, although the protrusion amount of the tip of the anode after lighting for 500 hours was 0.94 mm in the anode C of the conventional example, it was improved to 0.41 mm in the anode B of the comparative example, but this was further improved in the anode A of the present invention. It can be seen that the width is greatly reduced to 0.2 mm.

As a result, as shown in Table 2 and FIG. 13, the roughness retention of the i line was improved from 86% of the positive electrode C of the conventional example to 92% of the positive electrode B of the comparative example, but this was 96% in the positive electrode A of the present invention. More significant improvements are taking place.

As described above, the short arc discharge lamp according to the present invention is inserted into an opening formed in the center portion of the tip of the anode via a buffer material made of a metal having a lower yield stress than the anode material. The relief groove of the cushioning material is formed in at least one of the inner surface of the opening of the anode or the outer surface of the insert, so that the center portion of the tip of the anode is heated even when the full standby lighting method is adopted. Even if the buffer material inserted between the insert and the anode opening is thermally expanded, evaporation of the anode material as the center portion protrudes and a decrease in illuminance caused by blackening of the light emitting tube caused by the projection of the center portion are suppressed. Since the expanded matter penetrates into the relief groove and is absorbed and does not protrude from the tip surface of the anode, It shows an effect that the buffer material can be prevented from abnormally overheating and evaporating.

21: cathode 31: anode
32: electrode shaft 33: anode front end surface
34 opening 35 insert
36: shock absorber 37: first insert
38: second insert 41, 42: buffer material
43: crack 44: gap
45 through hole 46 annular opening
47: cushioning material
60: relief groove in the circumferential direction of the insert
61: relief groove in the circumferential direction of the opening
62: relief groove in the axial direction of the insert

Claims (11)

In a short arc type discharge lamp in which a pair of anodes and cathodes are disposed opposite to each other in a light emitting tube,
A short arc type discharge lamp comprising a buffer material made of a metal having a lower yield stress than the anode material between a center portion of the tip of the anode and a peripheral annular portion thereof. The method according to claim 1,
A short arc type discharge lamp, characterized in that the tip center portion is formed of an insert separate from the anode, and the insert is inserted through an opening in the opening formed in the anode tip surface. The method according to claim 2,
A short arc type discharge lamp, characterized in that the buffer member is made of metal foil and wound around the insert. The method according to claim 2,
A short arc type discharge lamp, characterized in that the insert comprises a ring-shaped first insert and a second insert inserted through the buffer insert through the first insert. The method according to claim 4,
A short arc-type discharge lamp, characterized in that the inner peripheral surface of the ring-shaped first insert has a crack extending radially on the tip surface of the anode. The method according to claim 4,
A short arc-type discharge lamp, characterized in that the ring-shaped first insert is divided into a plurality. The method according to claim 2,
The opening is a through hole penetrating to the rear end of the anode, and the insert is made of an electrode shaft, the electrode shaft is inserted into the through hole, and the front end thereof faces the front end surface of the electrode body. Type discharge lamp. The method according to claim 1,
A short arc type discharge lamp, characterized in that an annular opening is formed in the distal end surface of the anode to form the distal end portion and the peripheral annular portion, and a buffer material made of sintered metal is interposed in the annular opening. The method according to claim 3,
The relief arc of the said metal foil is formed in at least one of the inner surface of the said opening, or the outer surface of the said insert, The short arc type discharge lamp characterized by the above-mentioned. The method according to claim 9,
The said relief groove is formed in the circumferential direction, The short arc type discharge lamp characterized by the above-mentioned. The method according to claim 9,
The said relief groove is formed in the axial direction, The short arc type discharge lamp characterized by the above-mentioned.

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