JP2006012672A - Short arc type discharge lamp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a short arc type discharge lamp capable of suppressing degradation of light transmittance in an effective utilization range of a bulb to keep an illuminance maintenance rate high, and having a long service life. <P>SOLUTION: This short arc type discharge lamp is equipped with: the bulb 10 comprising an arc tube part 11 and sealing tube parts 12 at both its ends; a positive electrode 13 and a negative electrode 14 arranged oppositely to each other in the arc tube part 11; and electrode rods 15 mounted continuously to rear ends of the respective electrodes. The discharge lamp is characterized by that the positive electrode 13 includes a nearly cylindrical body part 13b and a tip part 13a formed continuously to the body part 13b and tapered toward a tip; and the positive electrode 13 is provided, around the body part 13b or at the rear end 13c, with projections 30 having circumferences radially expanded toward the rear side. The discharge lamp is also characterized by forming annular grooves around the electrode rod 15 on the rear end surface of the positive electrode 13. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a short arc type discharge lamp used for exposure of a semiconductor element, a liquid crystal element or a printed board element.

A short arc type discharge lamp used in the above technical field is described in, for example, Japanese Patent Application Laid-Open No. 2001-15070.
FIG. 7 is a sectional view of such a short arc type discharge lamp.
In the bulb 50 in the discharge lamp, a sealing tube portion 52 extending outward is connected to both ends of the arc tube portion 51. Inside the arc tube portion 51, a pair of electrodes 61 and 62 are fixed to the electrode rods 71 and 72, respectively, and are arranged to face each other with a predetermined interval.
The pair of electrodes 61 and 62 is made of tungsten, for example, an anode 61 having a substantially cylindrical shape as a whole and having a curved surface or an inclined surface formed so as to taper outward at the front end portion and the rear end portion, and the front end. And a cathode 62 shaped like a spire.
Such a short arc type discharge lamp is usually used with an appropriate optical system while being held in a vertical posture in which the anode 61 is on the top and the cathode 62 is on the bottom.

By the way, the lamp described above is a so-called blackening in which the evaporation of the electrode material adheres to the inner wall of the bulb 50 due to overheating of the anode 61 accompanying an increase in the current value and the light transmittance of the arc tube portion 51 is reduced. Is known to occur. The blackened product follows the arc while the lamp is lit and the convection R due to the arc flow (although convection similar to R is generated around the arc, it is not shown in the figure). Therefore, it easily adheres to the annular portion in the vicinity of the upper portion of the arc tube portion 51 indicated by P in the same figure, and is remarkably generated at that location.
Thus, a general optical system often uses light emitted from an angle range of about 45 ° above and below the center of the arc. (Hereinafter referred to as “effective use range”). Therefore, as long as the blackened material does not adhere within this range, there is no effect on the decrease in light emission.

Here, the convection in the valve according to the prior art will be described in detail with reference to FIG.
First, convection flows from the cathode 62 to the anode 61 in the vicinity of the center of the arc tube 51 along with the arc, from below to above as indicated by an arrow X1. Then, after colliding with a relatively low temperature air flow Y1 flowing vertically downward along the electrode rod 71 at the center of the anode 61, it spreads toward the arc tube 51 as indicated by an arrow X ′, and the arc tube portion 51 The inner wall is folded back and flows downward along the inner wall as indicated by an arrow X2.
Thus, the annular portion P at the top of the arc tube portion 51 is a location where the convection that has passed by the arc first collides with the inner wall of the arc tube portion 51 and is away from the arc and is at a relatively low temperature. The adhesion of objects occurs remarkably. Further, as the lighting time increases, the accumulation of blackened matter proceeds and the range also extends downward along the convection flow arrow X2.
JP 2001-15070 A

  As a result, in the short arc type discharge lamp described above, as the lamp lighting time elapses, electrode evaporates adhere to the inner wall in the effective use range of the bulb, the light transmittance decreases, and the light intensity of the lamp decreases, There is a problem that it becomes unusable early.

  Therefore, the problem to be solved by the present invention is to provide a short arc type discharge lamp having a long service life that can suppress a decrease in light transmittance in the effective use range of the bulb and maintain a high illuminance maintenance rate. It is in.

  In order to solve the above-mentioned problems, a short arc type discharge lamp according to the present invention includes a bulb comprising a luminous tube portion and a sealing tube portion provided to extend outward from both ends of the luminous tube portion, and a light emission of the bulb. A short arc type discharge lamp comprising an anode and a cathode disposed opposite to each other inside a tube portion, and an electrode rod continuously provided at the rear end of each electrode, wherein the anode has a substantially cylindrical shape. The anode has a tip portion that tapers toward the tip that is connected to the barrel portion, and the anode has an outer periphery that expands radially in the periphery or rear end portion of the anode and toward the rear. Protrusions that open are provided.

  Alternatively, a bulb comprising an arc tube portion and a sealing tube portion provided so as to extend outward from both ends of the arc tube portion, and an anode and a cathode disposed facing the inside of the arc tube portion of the bulb, A short arc type discharge lamp comprising an electrode rod provided continuously at the rear end of each electrode, wherein the anode is directed to a substantially cylindrical body portion and a front end connected to the body portion. And an annular groove is provided around the electrode rod on the rear end surface of the anode.

According to the present invention, when a flow along a protrusion or an annular groove is induced, a complicated flow is easily formed in a region behind the anode, and a complicated vortex is generated. Part of it is entrained to capture the evaporated material of the electrode material and circulate repeatedly by colliding with the tube wall of the bulb, the electrode rod, the protrusion, or the annular groove. At this time, since the evaporant adheres to the annular groove, electrode rod, and bulb tube wall, the flow toward the lamp inner wall surface in the center area of the lamp has a lower evaporant concentration, and the amount of evaporant adhering in the effective use range Is significantly reduced.
In addition, since the flow direction along the protrusion or the annular groove is regulated, it becomes stable in a state where the deposit of the evaporant is displaced above the bulb, and the region where blackening occurs is above the effective use range of the lamp. It becomes possible to reliably regulate the position.
As a result, the occurrence of blackening can be suppressed within the effective use range, the illuminance maintenance rate can be maintained high, and a short arc type discharge lamp having a long service life can be provided.

FIG. 1 is a sectional view of a short arc type discharge lamp illustrating an embodiment of the first invention of the present application.
In this discharge lamp, the bulb 10 is formed of quartz glass and has an elliptical spherical arc tube portion 11 surrounding the light emitting space S, and a cylindrical shape continuously connected to extend outward from both ends of the arc tube portion 11. A state in which a part of the sealing tube portion 12 is reduced in diameter at a location close to the luminous tube portion 11 of the sealing tube portion 12 following the luminous tube portion 11. The narrowing-down portion 12a is formed.

A pair of electrodes, that is, an anode 13 and a cathode 14 are arranged in the arc tube portion 11 of the bulb 10 so as to oppose each other, and each of them extends from the sealing tube portion 12 to the arc tube portion 11 along the tube axis. It is fixed and supported at the tip of a cylindrical electrode rod 15 made of, for example, tungsten. The arc tube portion 11 of the bulb 10 is filled with a noble gas such as xenon, argon, krypton or a mixture thereof, and a luminescent substance such as mercury.
In this short arc type discharge lamp, light radiated from an angle range (effective use range) of approximately 45 ° above and below the center of the arc is used.

  In the sealed tube portion 12 of the bulb 10, an electrode rod holding cylinder 16 made of quartz glass having a cylindrical hole with an inner diameter that matches the outer diameter of the electrode rod 15 is located close to the arc tube portion 11. The electrode rod 15 is disposed in a state where the electrode rod 15 is inserted, and the outer peripheral surface of the electrode rod holding cylinder 16 is hermetically welded to the inner surface of the narrowed portion 12a which is a part of the sealing tube portion 12, and the electrode rod One end face 16 a of the holding cylinder 16 is exposed to the light emitting space S. A sealing glass member 17 is disposed on the outer end side of the electrode rod holding cylinder 16 in the sealing tube portion 12. In the sealing glass member 17, the inner end portion 17a on the light emitting space S side is formed in a truncated cone shape having a diameter increasing toward the outer end, and the sealing tube portion is formed following the inner end portion 17a. A cylindrical body portion 17b having an outer diameter matching the inner diameter of 12 is formed. Further, the sealing glass member 17 is formed with a bottomed hole 17c extending in the axial direction from the outer end surface, and the bottomed hole 17c has an outer lead having an outer diameter suitable for the inner diameter. A rod 18 is inserted.

  On the outer peripheral surface of the sealing glass member 17, a plurality of strip-shaped metal foils 20 made of molybdenum are disposed apart from each other in the circumferential direction of the sealing glass member 17. The inner end portion extends along the inner end surface of the sealing glass member 17 and is connected to the electrode rod 15, and each outer end portion of the metal foil 20 extends along the outer end surface of the sealing glass member 17. Are connected to the external lead rod 18 and extend from the inner end of the sealing glass member 17 toward the outer end. Further, the outer peripheral surface of the sealing glass member 17 is hermetically welded to the inner surface of the sealing tube portion 12 via the metal foil 20.

  On the outer end side of the sealing glass member 17, a lead rod holding cylinder 19 made of quartz glass having a cylindrical hole that matches the outer diameter of the external lead rod 18 is inserted into the electrode rod 15. The outer peripheral surface of the lead rod holding cylinder 19 is hermetically welded to the inner surface of the sealing tube portion 12.

The anode 13 is made of, for example, tungsten, and has a tip portion 13a having a curved surface or a taper formed so as to taper toward the tip, as shown in the figure, and a substantially columnar shape behind the tip portion 13a. The body portion 13b is continuously provided.
The anode 13 is provided with a protrusion 30 at the rear end portion 13 c over the entire circumference of the anode 13. For example, the protrusion 30 is formed in a skirt shape so that the front end thereof is formed following the peripheral edge of the rear side of the anode 13 and the outer periphery of the protrusion 30 expands in the radial direction toward the rear. Such a skirt-like protrusion 30 can be provided by, for example, scraping a tungsten cylindrical body that is a material of the anode 13 at the stage of manufacturing the anode 13.
Here, the protrusion 30 is larger than 0 ° and smaller than 90 °, where θ is an angle formed by an imaginary line m parallel to the side surface of the protrusion 30 and an imaginary line n parallel to the side surface of the body portion 13b in FIG. It has been expanded to be at an angle. The angle θ formed is preferably obtained with reference to optical observation results of convection and the like, and an angle close to the flow when a stable convection is separated from the vicinity of the anode rear end portion 13c in the conventional lamp is set. Further, the position and length of the protrusion 30 may be set so that the flow B2 does not pass over the protrusion 30 and to the A2 side. As a result, the flow after peeling is formed along the protrusion. Even if the flow after peeling is not linear when there is no projection 30, it is only necessary to form a flow along this by the arrangement of the projection 30. Specifically, the angle is preferably 5 to 85 °, and more preferably 20 to 70 °.

FIG. 2 is a diagram for explaining convection during lighting of the lamp according to the present embodiment.
In the present embodiment, the convection flows first from below toward the anode 13 from the cathode 14 toward the anode 13 along with the arc in the vicinity of the center portion of the arc tube portion 11 as indicated by an arrow A1, and then the rear end portion of the anode 13 The direction is regulated by the protrusion 30 in the vicinity, and flows toward the upper portion Q of the arc tube portion 11 along the side surface of the protrusion 30 as indicated by an arrow A2. On the other hand, a relatively low temperature air flow indicated by an arrow B1 in the figure flows downward along the electrode rod 15 from the vicinity of the one end surface 16a of the electrode rod holding cylinder and hits the rear end surface 13d of the anode 13 to obtain a radius. Flowing outward in the direction and flowing toward the upper portion Q of the arc tube portion 11 along the inner peripheral surface of the protrusion 30 as indicated by an arrow B2.
Thus, the flow of the arrow A2 going upward from the vicinity of the arc and the flow of the arrow B2 going downward from the vicinity of the one end face 16a of the electrode rod holding cylinder are both restricted to the upper part Q of the arc tube portion 11. Therefore, the flow toward the upper portion Q of the arc tube portion 11 is stably formed. Therefore, most of the evaporated material of the electrode material is carried along stable convection, and collides with and adheres to the tube wall near the upper portion Q of the arc tube portion 11 above the effective use range of the bulb 10. In addition, a part of the electrode evaporant carried by the flow of A2 is captured on the surface of the protrusion 30 while flowing along the protrusion 30, and after passing through the protrusion 30, is joined by B2 Since it is taken in to the B2 side and carried by the flow of B3 behind the anode, the evaporant carried toward Q by the flow of A2 decreases. Accordingly, below the Q, the concentration of the evaporant contained in the convection A3 is remarkably reduced.
As a result, the probability that the evaporant adheres in the vicinity of the central portion of the arc tube portion 11 is remarkably reduced, and a decrease in light transmittance in the effective use range can be effectively suppressed.

As described above, since the decrease in light transmittance in the effective use range of the bulb can be suppressed by stabilizing the direction of convection after the merging of facing A2 and B2, the illuminance maintenance rate can be maintained high, A short arc discharge lamp having a long service life can be provided.
In the above, the case of peeling from the vicinity of the anode rear end portion 13C has been described. However, it is easily understood from the above that the disposition position of the protrusion 30 should be determined according to the peeling position that differs depending on the lamp. is there.

3 (a) and 3 (b) are cross-sectional views for explaining the main part of the lamp for explaining the embodiment according to the second aspect of the invention. With reference to Fig.3 (a), embodiment of 2nd invention of this application is described. 3A and 3B, the same components as those previously described with reference to FIGS. 1 and 2 are denoted by the same reference numerals, and the description thereof is omitted.
This embodiment is an example in which an annular groove 31 is provided around the electrode rod 15 on the rear end surface 13 d of the anode 13.
In the embodiment shown in the figure, the airflow flowing from the lower side to the upper side in the vicinity of the center portion of the arc tube portion 11 indicated by the arrow A1 in the drawing is the side surface of the anode 13 even in the vicinity of the rear end portion 13c of the anode 13. As shown by the arrow A2. On the other hand, the relatively low temperature air flow indicated by the arrow B1 flowing downward from the vicinity of the one end surface 16a of the electrode rod holding cylinder 16 enters the groove 31 formed in the rear end surface 13d of the anode 13, and the groove 31 The airflow (arrow A2) that has risen from the vicinity of the central portion of the arc tube portion described above is merged in a state in which the force that is turned back along the wall surface and is lowered downwards. Therefore, the flow toward the upper part of the arc tube portion 11 can be stably formed, and the same effect as described above can be obtained.
The cross-sectional shape of the anode rear end portion related to the annular groove 31 is not limited to the shape as shown in FIG. 3A, and the same effect can be obtained even when the shape is as shown in FIG. Is obtained.

FIGS. 4A and 4B are diagrams for explaining the third and fourth embodiments, respectively, and each invention includes the protrusion described in the first embodiment. Hereinafter, in the configuration, the same configuration as the configuration described above with reference to FIGS.
As shown to Fig.4 (a), the protrusion 30 may be provided on the outer peripheral surface of the trunk | drum 13b. However, in this case, in order to promote the flow to the upper portion Q of the arc tube 11, it is desirable that the protrusion 20 is attached so that the front end thereof is located behind the middle of the trunk 13 b.
According to this embodiment, as shown in the figure, the upward flow from the vicinity of the arc indicated by the arrow A1 and the downward flow from the vicinity of the sealing tube portion 12 indicated by the arrow B1 are respectively formed by the protrusions by the arrow A2. , B2 in the direction of B2, the flow toward the upper portion Q of the arc tube portion 11 is stably formed when these flow together. Therefore, after the air flow containing a large amount of the electrode material evaporate is reduced by trapping a part of the evaporate carried by the projection surface and further being taken in by the flow on the B2 side and carried away by the flow of B3. The lamp collides with the tube wall above the effective use range of the lamp, and the evaporated substance adheres to the tube wall, so that the concentration of the evaporated substance decreases in other areas.
As a result, it is possible to provide a short arc type discharge lamp having a long service life because the adhesion of the electrode material evaporant is reduced in the effective use range of the bulb, the decrease in the illuminance maintenance rate can be effectively suppressed.

In the fourth embodiment shown in FIG. 4B, the side surface of the anode body portion 13b is shaped so as to protrude radially outward toward the electrode rod 15 and the truncated cone-shaped projection 30 is formed. It is an example provided.
In this embodiment, the airflow that flows upward from the vicinity of the central portion of the arc tube portion 11 indicated by the arrow A1 rises in the direction of the arrow A2 while spreading slightly outward in the radial direction by the side surface of the protrusion 30. On the other hand, the airflow from the vicinity of one end surface 16a of the electrode rod holding cylinder 16 indicated by the arrow B1 spreads outward in the radial direction as indicated by the arrow B2 along the rear end surface 13d of the anode 13 and the bottom surface of the protrusion. At this time, the downward force of the airflow B2 is weakened, and the airflow A2 rising from the vicinity of the central portion of the arc tube portion 11 flows toward the upper portion of the arc tube portion 11 without being obstructed, and thus flows as indicated by an arrow.
Also in this embodiment, the flow toward the upper portion Q of the arc tube portion 11 can be stably formed, and the same effect as described above can be obtained.

FIGS. 5 (a) to 5 (c) are modifications of the first invention described in FIGS. 1 and 2, and are diagrams for explaining the fifth to seventh embodiments, both taking out the anode and the electrode rod. FIG.
FIG. 5A is a view showing an anode according to a fifth embodiment, which is an example in which a protrusion member which is a member different from the anode body is manufactured and attached to form a protrusion.
The protrusion member is made of, for example, a thin plate such as molybdenum having a thickness of 0.5 mm, and includes a skirt-like protrusion 30a and a welded portion 30b connected to the opening thereof. The projection 30 is attached by welding the welded portion 30b to the rear end surface 13d of the anode 13.
According to this embodiment, the airflow rising from the vicinity of the central portion of the arc tube portion is guided by the front surface of the protrusion 30a and flows toward the upper portion of the arc tube portion. Then, the airflow descending from the vicinity of the sealing tube portion strikes the rear end surface 13d of the anode, is then deflected by the rear end surface of the protrusion 30b, and merges with the upward airflow from the vicinity of the central portion of the arc tube portion. Head to the top. As described above, since both the air flow from the vicinity of the central portion of the arc tube portion and the air flow descending from the vicinity of the sealing tube portion are directed to the upper portion of the bulb, stable convection can be formed.

  FIG. 5B is a diagram for explaining the sixth embodiment. In the present embodiment, as a protrusion member, for example, a spiral spring made of a strand of tungsten or the like having a diameter of 1 mm is manufactured, and this is fitted to the anode rear end portion 13c to form the protrusion 30. This is an example. The protrusion 30 is attached by welding the inner end thereof to the anode rear end portion 13c in a state where the outer periphery of the spring gradually expands in the radial direction from the rear end of the anode 13. Use of such a helical spring is preferable because the projection can be provided relatively easily.

  FIG. 5C is a diagram for explaining the seventh embodiment. In the present embodiment, a constricted portion 13e is formed on the anode 13 behind the middle of the trunk portion 13b so that the outer diameter of the trunk portion 13b is locally small, and rearward of the constricted portion 13e. In this example, the protrusions 30 are formed. Thus, the shape of the trunk | drum 13b does not need to be perfect cylinder shape. If the protrusion 30 is continuously provided behind the trunk portion 13b as in the present embodiment, the rising airflow can be restricted and stable convection can be formed.

Needless to say, in the fifth to seventh embodiments, the same operations and effects as those of the previous embodiment can be obtained.
Further, in the embodiment of FIG. 4A, the same effect can be obtained even if a projection made of a member different from the anode is attached as shown in FIGS. 5A and 5B. Needless to say.
Needless to say, the specifications and the like of each embodiment are merely examples, and can be changed as appropriate.

A short arc type discharge lamp according to the fifth embodiment shown in FIG. 5A was produced according to the following specifications, and the lamp of Example 1 was obtained.
Rated power consumption: 3.5kW
Arc tube dimensions: 70mm diameter, arc tube length 100mm
Filling gas: Argon 40 kPa (25 ° C.)
Enclosed mercury: 5.5g
Anode: Diameter 20mm, length 30mm
Projection member: thickness 0.5 mm, material molybdenum, axial length 6 mm, opening angle 30 ° with respect to anode side surface

Similarly, the short arc discharge lamp according to the second embodiment shown in FIG. 3A was produced according to the following specifications, and the lamp of Example 2 was obtained.
Rated power consumption: 5kW
Arc tube dimensions: diameter 80mm, arc tube length 110mm
Filled gas: Argon 65 kPa (25 ° C.)
Enclosed mercury: 8.5g
Anode: 25mm diameter, 35mm length
Groove depth: 10 mm, groove width 4 mm

  The lamps according to Examples 1 and 2 were manufactured as Comparative Examples 1 and 2, respectively, by manufacturing the lamps according to the related art so as to have the same specifications except that no protrusions or grooves were formed. The lamps according to Examples 1 and 2 and Comparative Examples 1 and 2 were turned on to measure the illuminance maintenance rate. These results are shown in FIGS. 6 (a) and 6 (b). In the figure, the vertical axis represents the illuminance maintenance ratio (relative value) with the illuminance at the beginning of lighting set to 100, and the horizontal axis represents the lighting time (h).

  FIG. 6A is a result of measuring the illuminance maintenance rate of the lamp according to Example 1 and the lamp according to Comparative Example 1 according to the related art. From this result, it can be seen that the illuminance maintenance rate has been greatly improved. For example, in the lamp of Example 1 (3.5 kW lamp), at the lighting time of 750 h, the lamp of Comparative Example 1 (conventional) was 75, but the lamp according to the present example became 86.8, which is about 11 An improvement effect of .8% was obtained.

  Moreover, FIG.6 (b) is the result of having measured the illumination intensity maintenance factor of the lamp | ramp which concerns on Example 2, and the lamp | ramp which concerns on the comparative example 2 which concerns on the prior art. In the lamp of Example 2, the illuminance maintenance rate was improved. At the lighting time of 750 h, the lamp of Comparative Example 2 (conventional) was 73.5, but the lamp according to this example became 82, which was about 8.5. % Improvement effect was obtained.

It is sectional drawing explaining 1st embodiment. It is a figure explaining the convection during lighting of a lamp. It is sectional drawing for description of the lamp | ramp principal part explaining embodiment which concerns on invention of Claim 2, (a) 2nd embodiment of this application, (b) It is a figure explaining other embodiment. It is a figure explaining (a) 3rd embodiment and (b) 4th embodiment, respectively. It is sectional drawing for description which takes out and shows the anode and electrode rod which respectively explain (a) 5th embodiment, (b) 6th embodiment, (c) 7th embodiment. It is a figure which shows the illumination intensity maintenance factor of (a) Example 1 and the comparative example 1, respectively (b) Example 2 and the comparative example 2. FIG. It is sectional drawing which expands and shows the principal part of the conventional short arc type discharge lamp. It is a figure explaining the convection of the conventional short arc type discharge lamp.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Bulb 11 Light emission tube part 12 Sealing tube part 13 Anode 14 Cathode 15 Electrode rod 16 Electrode rod holding cylinder 17 Sealing glass member 18 External lead rod 19 Lead rod holding cylinder 20 Metal foil 30 Protrusion 31 Groove S Luminous space

Claims (2)

A bulb comprising an arc tube portion and a sealed tube portion extending outward from both ends of the arc tube portion, an anode and a cathode disposed opposite to the inside of the arc tube portion of the bulb, and after each electrode A short arc type discharge lamp comprising an electrode rod connected to the end,
The anode has a substantially cylindrical body portion and a tip portion that tapers toward a tip continuously provided on the barrel portion,
The short-arc discharge lamp according to claim 1, wherein the anode is provided with a protrusion, the outer periphery of which is radially expanded toward the rear, on the periphery or rear end of the body. A bulb comprising an arc tube portion and a sealed tube portion extending outward from both ends of the arc tube portion, an anode and a cathode disposed opposite to the inside of the arc tube portion of the bulb, and after each electrode A short arc type discharge lamp comprising an electrode rod connected to the end,
The anode has a substantially cylindrical body portion and a tip portion that tapers toward a tip continuously provided on the barrel portion,
A short arc type discharge lamp, wherein an annular groove is provided around the electrode rod on a rear end surface of the anode.

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