CN109390208B - Short arc type discharge lamp - Google Patents

Abstract

The invention provides a short arc type discharge lamp, a pair of cathode and anode are oppositely arranged in the luminous tube and are vertically lighted, wherein, the blackening matter such as metal evaporated from the electrode or electrode core wire in the luminous tube is prevented from being transported by convection gas when being lighted and attached to the inner wall of the luminous tube to be blackened, and the non-evaporation of mercury caused by the temperature reduction in the upper region of the luminous tube is prevented, and the illumination maintenance rate is high in a long time. The short arc discharge lamp is characterized in that a convection guide member having a through hole in the tube axis direction is provided above an electrode located at an upper position in the light emitting tube, and the temperature of the upper region of the light emitting tube is prevented from decreasing so that a part of the convection gas in the light emitting tube passes through the convection guide member.

Description

Short arc type discharge lamp

Technical Field

The present invention relates to a short arc type discharge lamp, and more particularly, to a short arc type discharge lamp which is vertically lighted.

Background

Conventionally, a vertical lighting system in which a pair of electrodes disposed to face each other are disposed vertically to light a discharge lamp of a short arc type with high input and high luminance has been widely used.

Further, since a short arc discharge lamp in which a pair of a cathode and an anode are disposed facing each other in a mercury-sealed light emitting tube is close to a point light source, it is used as a light source of an exposure apparatus having a high light collecting efficiency by combining with an optical system.

Further, a short arc type discharge lamp in which xenon is sealed in a light emitting tube is used as a light source for digital cinema.

In such a short arc type discharge lamp, it is known that evaporation of an electrode material due to overheating of an anode or the like occurs because a thermal load acting on the anode at the time of lighting is high, and the evaporated material adheres to an inner wall of a light emitting tube to cause so-called blackening in which light transmittance is decreased. Such a blackened material is transported by convection of the gas being lit, and easily adheres to the vicinity of the upper portion of the arc tube.

As a method of capturing a blackened material due to evaporation of such an electrode material from a convective gas, japanese patent application laid-open No. 2005-340136 (patent document 1) discloses that a disk-shaped member is provided above an electrode (anode) located above.

Fig. 6 shows this structure, in which a pair of cathodes 103 and anodes 104 are arranged to face each other in an arc tube 102 of a short arc type discharge lamp 101, and the lamp 101 is lit vertically with the anodes 104 positioned above. The upper anode 104 is provided with a disk-shaped member 110 on the core wire 104a.

As shown in fig. 6, during lamp lighting, convection X of gas due to arc is generated in the arc tube 102, but collides with the disk-shaped member 110 above the anode 104 and flows along the inner wall of the arc tube 102. The flow to the upper side of the anode 104 collides with the disk-shaped member 110, and the blackened substance in the convection gas adheres to the disk-shaped member 110 and the anode core wire 104a during this time. Thus, almost no blackening material is contained in the convection current flowing along the inner wall of the light-emitting tube 102, and blackening of the light-emitting tube 102 can be suppressed.

However, it is known that when the disc-shaped member 110 is provided as in patent document 1, the convective gas X rising along the periphery of the anode 104 is blocked by the disc-shaped member 110 and does not flow to the upper end portion inside the arc tube 102, and the non-evaporation of mercury occurs in this region, and a desired lamp life (illuminance maintenance ratio) cannot be obtained.

Documents of the prior art

Patent document 1: japanese patent laid-open No. 2005-340136

Disclosure of Invention

Problems to be solved by the invention

The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to provide a structure of a short arc type discharge lamp in which a pair of a cathode and an anode are disposed in opposition to each other inside an arc tube and are vertically lit, wherein a metal or the like evaporated from an electrode, a core wire, or the like is prevented from being carried by a convective gas generated in the arc tube and adhering to a tube wall of the arc tube to be blackened, and the convective gas in the arc tube is made to flow to an upper end portion of the arc tube to suppress non-evaporation of mercury.

Means for solving the problems

In order to solve the above problem, the present invention is characterized in that a convection guide member is provided above the electrode at an upper position, and a through hole in a tube axis direction is formed in the convection guide member.

Further, the convection current guide member is formed in a disc shape.

Further, the through holes are provided at equal intervals on the same circumference around the pipe axis.

Further, the rear end of the electrode at the upper position is provided with an inclined portion whose diameter decreases toward the rear.

Further, the through-hole is located outward of an imaginary line obtained by extending the inclined portion when viewed from the pipe axial direction.

Effects of the invention

According to the present invention, the convection guide member having the through hole is provided above the electrode at the upper position, so that the convection gas in the light emitting tube flows to the upper end portion of the light emitting tube through the through hole of the convection guide member, and the non-evaporation of the mercury can be suppressed without causing a temperature decrease in the region. Further, the flow of the gas folded back downward from the convection guide member is generated, so that the occurrence of disturbance in the convection gas in the light emitting tube is reduced, and fluctuation of the arc is reduced, thereby stably maintaining the lighting. In addition, the blackened material in the convection gas flowing upward adheres to the convection guide member and the electrode core wire, and also adheres to the inner surface of the through hole, and is removed from the convection gas, so that the blackened material can be prevented from adhering to the inner wall of the arc tube.

Further, by providing the inclined portion with a reduced diameter at the rear end of the upper electrode, the convective gas flows along the electrode core line through the inclined portion, and flows efficiently through the through hole of the convective guide member, thereby further suppressing non-evaporation of mercury at the upper end portion of the arc tube.

Drawings

Fig. 1 is a sectional view of a short arc type discharge lamp of the present invention.

Fig. 2 (a) is a partially enlarged sectional view of fig. 1, and fig. 2 (B) is a plan view of the convection current guiding member.

Fig. 3 is another embodiment of the through-hole in the convection directing member.

Fig. 4 is a diagram showing a behavior of convection of gas in the light emitting tube.

Fig. 5 is a graph showing the effect of the illuminance maintenance ratio according to the present invention.

Fig. 6 is a sectional view of the conventional example.

Detailed Description

Fig. 1 shows a short arc discharge lamp 1 of the present invention which is vertically lighted, a cathode 3 and an anode 4 are disposed opposite to each other in a luminous vessel 2, and core wires 5 and 6 of the cathode 3 and the anode 4 are sealed in sealing portions 7 and 8, respectively.

The electrode located above when lit, in this embodiment the anode 4, is provided with a convection directing member 10 above it.

The convection guide member 10 is formed of a disc-shaped member and is attached to the core wire 6 of the anode 4 by an attachment member 9. A plurality of through holes 11 are formed in the convection guide member 10 in the pipe axial direction.

Fig. 2 shows details of the convection guide member 10, and as shown in fig. 2B, a plurality of through holes 11 are formed in the disc-shaped convection guide member 10 at equal intervals on the same circumference around the tube axis (the central axis of the arc tube 2, that is, the central axis of the cathode 3 and the anode 4) Y. In this example, six through holes 11 are formed, and the number thereof can be appropriately selected according to the size (diameter) of the convection current guide member 10, the opening diameter of the through holes 11, and the like.

On the other hand, a slope 4a whose diameter decreases toward the rear (upward) is provided at the rear end of the anode 4. The reduced diameter portion 4a is typically formed by a tapered portion.

The through hole 11 of the convection guide member 10 is preferably located on the outer side (upper side) than the virtual line L obtained by extending the inclined portion 4a when viewed from the direction of the tube axis Y.

The shape of the through-hole 11 may be not only a circular shape as shown in fig. 2 (B), but also a plurality of slit-like elongated holes extending in the circumferential direction as shown in fig. 3.

The convection of the gas in the arc tube 2 of the present invention will be described below with reference to fig. 4.

In the arc tube 2, the gas X heated by the arc between the cathode 3 and the anode 4 rises in the arc tube 2 along the anode 4 and reaches the convection guide member 10. Here, a part of the flow X1 turns over and flows downward along the inner wall surface of the arc tube 2.

Further, since the through hole 11 is formed in the convection guide member 10, a part X2 of the convection gas X flows through the through hole 11 to the upper end portion inside the arc tube 2.

At this time, the through-hole 11 is positioned further to the outside (upper side) than the virtual line L obtained by extending the inclined portion 4a at the rear end of the anode 4 when viewed from the tube axis Y direction, and thus the part X2 of the rising convective gas X easily flows into the through-hole 11 more smoothly.

In this way, the entire upper region of the arc tube 2 is heated by the gas X2 passing through the convection guide member 10, and the non-evaporation of mercury can be suppressed without forming the coldest spot. Further, the gas X1 folded back downward from the convection guide member 10 reduces disturbance in the convection gas in the arc tube 2, reduces fluctuation of the arc, and stably maintains lighting.

During this time, the blackened substance in the convection gas X collides with the anode core wire 6 or the convection guide member 10 and adheres thereto, and also adheres to the inner surface of the through hole 11, and is removed from the convection gas.

A specification example of the short arc type discharge lamp of the present invention is shown below.

< example >

Input: rated input of 12kW and rated current of 100A

Lighting posture: vertical lighting above the anode

Cathode:

cathode material: thorium tungsten

Cathode size:

the total length is 30mm

Cathode core wire:

anode:

anode material: tungsten (W)

Anode size:

the total length is 50mm

Diameter of the front end portion: 8mm

Tip taper angle: 120 degree

Rear end taper angle: 90 deg. C

Diameter of the rear end portion: 25mm

An anode core wire:

on the anode body part, a laser groove

Interpolar: 11mm

Convection directing means:

materials: tungsten

Shape: six through holes are formed on the circular plate

The size of the circular plate is as follows:

thickness of 2mm

Arrangement of through holes: in that

Are arranged at the same pitch (60 DEG) on the circumference of the cylinder head

Fixing the position: rear (upper) 20mm of rear end of anode

The fixing method comprises the following steps: held by tungsten coils from above and below

< comparative example >

In the structure shown in fig. 6, the disk-shaped member has no through-hole. Other specifications are the same as those of the embodiment.

The illuminance maintenance ratios were measured for the lamps of examples and comparative examples. The results are shown in FIG. 5.

It is understood that the light-on time of 1000 hours in the comparative example was reduced to about 76% of the initial illuminance, while the light-on time was maintained at 93% of the initial illuminance in the example of the present invention.

The reason why the illuminance maintenance ratio is improved in the short arc discharge lamp of the present invention is presumed as follows.

In the short arc type discharge lamp of the embodiment, no non-evaporation of mercury occurs in the upper region of the arc tube, and therefore mercury does not repeat evaporation and condensation in this region. This cycle of evaporation and condensation of mercury destabilizes the arc and promotes evaporation and loss of the electrodes, but this phenomenon does not occur in the short arc type discharge lamp of the example. As a result, the short-arc discharge lamp of the example had a better change in the illuminance maintenance rate than the comparative example.

In the above description, the case of the vertical lighting system in which the anode is at the upper position has been described, but the vertical lighting system in which the cathode is at the upper position may be employed.

The lighting posture is not limited to the lighting mode of strictly 90 ° to the horizontal direction, and may be a lighting mode of substantially 90 ° (vertical).

As described above, according to the present invention, in the short arc type discharge lamp which is vertically lit, the convection guide member having the axial through hole is provided above the electrode which is located at the upper position in the light emitting tube, and a part of the convection gas in the light emitting tube is guided upward through the through hole, so that the temperature of the upper end portion in the light emitting tube is maintained at a high temperature, the coldest spot is not formed, and the non-evaporation of mercury in the region can be suppressed.

Further, the flow of the gas folded back downward from the convection guide member is generated, so that the occurrence of disturbance in the convection gas in the light emitting tube is reduced, and fluctuation of the arc is reduced, thereby maintaining stable lighting.

The blackened substance contained in the convection gas collides with the core wire of the upper electrode and the convection guide member and adheres to the inner surface while passing through the through hole, and is removed from the convection gas.

In addition, by forming an inclined portion at the rear end portion of the upper electrode and disposing the through hole of the convection guiding member at a position further outward than the extension line of the inclined portion, the convection gas rising along the upper electrode is smoothly introduced into the through hole of the convection guiding member.

Description of the reference numerals

1: short arc type discharge lamp

2: luminous tube

3: cathode electrode

4: anode

4a: inclined part

5: cathode core wire

6: anode core wire

7. 8: sealing part

9: mounting component

10: convection current guide member

11: through hole

X: convection gas

X1: part of the convection gas

X2: rising part of convective gas

Y: tubular axis center (electrode axis center)

L: an extension line of the inclined portion.

Claims (5)

1. A short arc type discharge lamp in which a pair of a cathode and an anode are disposed in opposition to each other inside a light emitting tube and are lit vertically, characterized in that

A convection guide member is provided above the rear end of the electrode at the upper position,

the convection guide member is formed with a through hole in the pipe axial direction.

2. The short arc type discharge lamp according to claim 1,

the convection guide member has a circular plate shape.

3. The short arc type discharge lamp according to claim 1,

the through holes are arranged at equal intervals on the same circumference with the pipe shaft as the center.

4. The short arc type discharge lamp according to claim 1,

an inclined portion whose diameter is reduced toward the rear is provided at the rear end of the electrode at the upper position.

5. The short arc type discharge lamp according to claim 4,

the through hole is located on the outer side of an imaginary line obtained by extending the inclined part when viewed from the pipe axis direction.

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