JP6941275B2 - Short arc type discharge lamp - Google Patents

Description

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

Conventionally, in a short arc type discharge lamp having a high input and a high brightness, a vertical lighting method in which a pair of electrodes arranged opposite to each other are vertically arranged and lit is often used.
In addition, a short arc type discharge lamp in which a pair of cathodes and an anode are arranged facing each other in an arc tube filled with mercury is close to a point light source, and therefore, by combining with an optical system, it can be used as a light source for an exposure device having high light collection efficiency. It's being used.
Further, a short arc type discharge lamp in which xenon is sealed in an arc tube is used as a light source for digital cinema.
In such a short arc type discharge lamp, since the thermal load applied to the anode at the time of lighting is high, the electrode material evaporates due to overheating of the anode and the like, and this evaporation adheres to the inner wall of the arc tube. It is known that so-called blackening occurs in which the light transmittance decreases. Such blackened matter is carried by the convection of the lighting gas and easily adheres to the vicinity of the upper part of the arc tube.

In Japanese Patent Application Laid-Open No. 2005-340136 (Patent Document 1), as a device for capturing black matter due to evaporation of such an electrode material from the convection gas, a disk-shaped member is provided above the electrode (anode) located above. It is disclosed to provide.
The structure is shown in FIG. 6, in which a pair of cathodes 103 and an anode 104 are arranged to face each other in the arc tube 102 of the short arc type discharge lamp 101, and the lamp 101 is vertical with the anode 104 facing upward. It is lit. A disk-shaped member 110 is provided on the core wire 104a of the upper anode 104.

As shown in FIG. 6, while the lamp is lit, gas convection X due to an arc is generated in the arc tube 102, but it collides with the disk-shaped member 110 above the anode 104 and flows along the inner wall of the arc tube 102. .. Since the upward flow of the anode 104 collides with the disk-shaped member 110, the blackened material in the convection gas adheres to the disk-shaped member 110 and the anode core wire 104a during this period. As a result, the convection flowing along the inner wall of the arc tube 102 contains almost no blackened matter, and the blackening of the arc tube 102 can be suppressed.

However, as in Patent Document 1, when the disc-shaped member 110 is provided, the convection gas X rising along the periphery of the anode 104 is blocked by the disc-shaped member 110, and the upper end portion inside the arc tube 102 is provided. It was found that there is a problem that the desired lamp life (illuminance maintenance rate) cannot be obtained because mercury does not evaporate in that region.

Japanese Unexamined Patent Publication No. 2005-340136

In view of the above problems of the prior art, the present invention is a short arc type discharge lamp in which a pair of cathodes and an anode are arranged to face each other inside the arc tube and are vertically lit. Evaporated metal etc. is transported from the core wire etc. to prevent it from adhering to the tube wall of the arc tube and blackening, and the convection gas in the arc tube is made to flow to the upper end of the arc tube to prevent mercury. It provides a structure in which unevaporation is suppressed.

In order to solve the above problems, the present invention is characterized in that a convection guiding member is provided above the electrode located at an upper position, and the convection guiding member is formed with a through hole in the pipe axis direction. ..
Further, the convection guiding member is characterized in that it has a disk shape.
Further, the through holes are provided at equal pitches on the same circumference centered on the pipe axis.
Further, the rear end of the electrode located at the upper position is provided with an inclined portion whose diameter is reduced toward the rear.
Further, the through hole is characterized in that it is located on the outer side of the pipe axis with respect to the virtual line extending the inclined portion.

According to the present invention, by providing the convection guiding member having a through hole above the electrode at the upper position, the convection gas in the arc tube passes through the through hole of the convection guiding member to the upper end of the arc tube. It will flow, and the unevaporation of mercury can be suppressed without causing a temperature drop in this region. Further, due to the flow of gas that is folded downward from the convection induction member, the convection gas in the arc tube is less likely to be disturbed, the fluctuation of the arc is reduced, and the lighting is stably maintained. Further, the blackened matter in the convection gas flowing upward adheres to the convection guiding member and the electrode core wire, and further adheres to the inner surface of the through hole, is removed from the convection gas, and emits light of the blackened matter. It can prevent adhesion to the inner wall of the pipe.
Further, since the inclined portion having a reduced diameter is provided at the rear end of the upper electrode, the convection gas flows along the electrode core wire side by this inclined portion, and this effectively flows through the through hole of the convection guiding member. , The unevaporation of mercury at the upper end of the arc tube can be further suppressed.

Sectional drawing of the short arc type discharge lamp of this invention. FIG. 1 is an enlarged cross-sectional view (A) of a part of FIG. 1, and a plan view (B) of a convection guiding member. Other Examples of Through Holes in Convection Induction Members. The behavior diagram of the convection of the gas in the arc tube. The graph which shows the effect about the illuminance maintenance rate of this invention. Sectional view of the conventional example.

FIG. 1 shows a short arc type discharge lamp 1 that is vertically lit according to the present invention, in which a cathode 3 and an anode 4 are arranged to face each other in an arc tube 2, and the core wire 5 and the anode 4 of the cathode 3, respectively. The core wire 6 is sealed at the sealing portions 7 and 8.
A convection guiding member 10 is provided above the electrode located above when lit, and above the anode 4 in this embodiment.
The convection induction member 10 is made of a disk-shaped member, and is attached to the core wire 6 of the anode 4 by the attachment member 9. A plurality of through holes 11 in the pipe axis direction are formed in the convection guiding member 10.

The details of the convection guiding member 10 are shown in FIG. 2, and as shown in FIG. 2 (B), the disk-shaped convection guiding member 10 has a tube shaft (the central axis of the arc tube 2, that is, the cathode). 3. A plurality of through holes 11 are formed at equal pitches on the same circumference centered on Y (the central axis of the anode 4). In this example, six through holes 11 are formed, but the number thereof is appropriately selected depending on the size (diameter) of the convection guiding member 10, the opening diameter of the through holes 11, and the like.
On the other hand, the rear end of the anode 4 is provided with an inclined portion 4a whose diameter is reduced toward the rear (upward). The reduced diameter portion 4a is typically formed of a tapered portion.
The through hole 11 of the convection guiding member 10 is preferably provided so as to be located on the outer side (upper side) of the virtual line L extending the inclined portion 4a when viewed from the pipe axis Y. ..
Further, the shape of the through hole 11 is not limited to the circular shape shown in FIG. 2B, but may be a plurality of slit-shaped elongated hole shapes extending in the circumferential direction as shown in FIG.

Based on FIG. 4, the convection of gas in the arc tube 2 in the present invention will be described as follows.
The gas X warmed by the arc between the cathode 3 and the anode 4 in the arc tube 2 rises in the arc tube 2 along the anode 4 and reaches the convection induction member 10. Here, a part of X1 reverses the flow and flows downward along the inner wall surface of the arc tube 2.
Further, since the convection guiding member 10 is formed with a through hole 11, a part X2 of the convection gas X flows through the through hole 11 to the upper end portion in the arc tube 2.
At this time, the position of the through hole 11 is on the outer side (upper side) of the virtual line L extending the inclined portion 4a at the rear end of the anode 4 when viewed from the pipe axis Y, so that the convection gas X rises. Part of X2 is made easier to flow into the through hole 11 more smoothly.

In this way, the entire upper region of the arc tube 2 is not heated by the gas X2 that has passed through the convection induction member 10 to form the coldest point, and the unevaporation of mercury is suppressed. Further, the gas X1 that is folded downward from the convection induction member 10 reduces the occurrence of turbulence in the convection gas in the arc tube 2, reduces the fluctuation of the arc, and keeps the lighting stable.
During this period, the blackened material in the convection gas X collides with the anode core wire 6 and the convection guiding member 10 and adheres to it, and further adheres to the inner surface of the through hole 11 and is removed from the convection gas. NS.

A specification example of the short arc type discharge lamp of the present invention is shown below.
<Example>
・ Input: Rated input 12kW, rated current 100A
・ Lighting posture: Vertical lighting above the anode ・ Cathode:
Cathode material: Triated tungsten Cathode dimensions: φ25 mm, total length 30 mm
Cathode core wire: φ8 mm
·anode:
Anode material: Tungsten Anode dimensions: φ35 mm, total length 50 mm
Tip diameter: 8 mm
Tip taper angle: 120 °
Rear end taper angle: 90 °
Rear end diameter: 25 mm
Anode core wire: φ8 mm
Laser groove on the anode body ・ Between poles: 11 mm
・ Convection induction member:
Material: Tungsten Shape: 6 through holes in the disk Dimensions of the disk: φ32 mm, thickness 2 mm
Arrangement of through holes: 6 at the same pitch (60 °) on the circumference of φ20 mm Fixed position: 20 mm behind (upper) the rear end of the anode
Fixing method: Hold from above and below with a tungsten coil

<Comparison example>
In the structure shown in FIG. 6, the disk-shaped member has no through hole. Other specifications are the same as in the examples.

The illuminance maintenance rate was measured for the lamps of Examples and Comparative Examples. The result is shown in FIG.
In the comparative example, it can be seen that the lighting time is reduced to about 76% of the initial illuminance after 1000 hours, whereas in the embodiment of the present invention, it is maintained at 93% of the initial illuminance.

In the short arc type discharge lamp of the present invention, the reason why the illuminance maintenance rate is improved as described above is presumed as follows.
In the short arc type discharge lamp of the embodiment, since mercury non-evaporation does not occur in the upper region of the arc tube, mercury does not repeatedly evaporate and condense in this region. This mercury evaporation / condensation cycle destabilizes the arc and promotes evaporation and wear of the electrodes, but such a phenomenon does not occur in the short arc type discharge lamp of the embodiment. As a result, the short arc type discharge lamp of the example had a better illuminance maintenance rate than the comparative example.

In the above description, the case of the vertical lighting method in which the anode is in the upper position has been described, but the vertical lighting method in which the cathode is in the upper position may be used. In that case, the convection guiding member is in the upper position. It is mounted above the cathode at.
Further, although vertical lighting is used, the lighting posture is not limited to strictly 90 ° with respect to the horizontal, and a lighting method of approximately 90 ° (vertical) may be used.

As described above, according to the present invention, in the vertically lit short arc type discharge lamp, a convection guiding member having an axial through hole is provided above the electrode located at an upper position in the arc tube. Since a part of the convection gas in the arc tube is guided upward through this through hole, the temperature of the upper end portion in the arc tube is kept at a high temperature state and the coldest point is not formed, and mercury in this region is not formed. Unevaporation can be suppressed.
Further, due to the flow of gas that is folded downward from the convection induction member, the convection gas in the arc tube is less likely to be disturbed, the fluctuation of the arc is reduced, and the lighting is stably maintained.
Further, the blackened matter contained in the convection gas collides with the core wire of the upper electrode and the convection guiding member and adheres to the convection gas, and is removed from the convection gas by adhering to the inner surface thereof while passing through the through hole. NS.
Then, by forming an inclined portion at the rear end portion of the upper electrode and arranging the position of the through hole of the convection guiding member on the outer side of the extension line of the inclined portion, the convection rising along the upper electrode The gas is smoothly guided to the through hole of the convection guiding member.

1: Short arc type discharge lamp 2: Light arc tube 3: Cathode 4: Anode 4a: Inclined part 5: Cathode core wire 6: Anode core wire 7, 8: Sealing part 9: Mounting member 10: Convection induction member 11: Through hole X : Convection gas X1: Part of convection gas X2: Part of rise of convection gas Y: Center of tube axis (center of electrode axis)
L: Extension line of the inclined part

Claims (5)

In a short arc type discharge lamp in which a pair of cathodes and an anode are arranged to face each other inside the arc tube and are vertically lit.
A convection guiding member is provided above the rear end of the electrode located above.
A short arc type discharge lamp characterized in that a through hole in the pipe axis direction is formed in the convection induction member. The short arc type discharge lamp according to claim 1, wherein the convection induction member has a disk shape. The short arc type discharge lamp according to claim 1, wherein the through-holes are provided at equal pitches on the same circumference centered on the pipe axis. The short arc type discharge lamp according to claim 1, wherein an inclined portion whose diameter is reduced toward the rear is provided at the rear end of the electrode located at the upper position. The short arc type discharge lamp according to claim 4, wherein the through port is located on the outer side of the tube axis with respect to the virtual line extending the inclined portion.

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