JPH0539564Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of the Technology] The present invention relates to a short arc type high pressure mercury lamp used in a DC power source.

[Conventional technology]

A short-arc type high-pressure mercury lamp used for lighting with a DC power source has a tungsten anode and a cathode placed within a light bulb made of quartz glass with a high heat-resistant temperature, with a distance between the electrodes of about 1 mm to 6 mm.
Inside, along with the starting gas, mercury is sealed in an amount that increases the vapor pressure from around 1 atm to 50 atm when the lamp is turned on.

Such a discharge lamp has a short distance between electrodes and can provide high brightness, so it is preferably used as a light source for semiconductor exposure equipment. By the way, in recent years, as a light source for semiconductor exposure equipment, semiconductor wafers have become larger and throughput has increased (shorter exposure processing time).
There is a tendency towards higher output due to these factors. Those with relatively small output are, for example, Utility Application No. 49-102752
-30377) is sufficient, but it was found that further improvements were needed for those with power consumption of 1KW or more.

That is, as power consumption increases, the current value generally increases, although it depends on the design values of the current and voltage of the discharge lamp, and accordingly, the volume of the anode, which is subject to electron collisions, increases, becomes thicker, and becomes longer.

The volume of the anode of a short-arc type high-pressure mercury lamp for semiconductor exposure equipment is also discussed in Japanese Patent Application Laid-Open No. 108478/1983, taking lighting conditions and other factors into consideration. Although the aim here is to reduce damage to the anode, it is required that the mercury reach a predetermined vapor pressure as quickly as possible due to the usage of the discharge lamp.

On the other hand, with regard to the anode, there is no need to take into account whether the electron emission is good or bad, so from the viewpoint of simply preventing damage, it is sufficient to increase the volume so that the overall temperature does not rise easily. In this case, not only is it difficult to manufacture the discharge lamp, but the space behind the anode becomes large, and the temperature of the bulb behind the anode becomes difficult to rise, so it takes time to bring the mercury vapor to the specified pressure. . This tendency becomes a particularly serious drawback when lighting is performed with the anode located below.

By the way, for short-arc type mercury lamps that are lit with the anode positioned below, the technology for keeping the bulb part behind the anode warm was developed, for example, in the 1970s.
Metallic reflective coatings or ceramic protective coatings, as seen in the 32955, have been used, but it has been found that there are other techniques that are better when the anode is large.

[Purpose of the invention] The present invention was made in consideration of the above circumstances, and it is a short arc type high pressure mercury lamp that has a large anode and is used for lighting with the anode positioned below. It is an object of the present invention to provide a novel discharge lamp having a structure in which the space is reduced and the temperature of the inner wall of the bulb portion behind the anode is quickly raised.

[Means to achieve the purpose]

In the present invention, a short-arc type high-pressure mercury lamp includes a light-emitting bulb surrounding a discharge space, a branch pipe section continuing to the tip of the light-emitting bulb, a cathode and an anode arranged oppositely in the light-emitting bulb, and supporting the cathode and the anode. an internal lead rod held in the branch pipe section, the anode is separate from the internal lead rod, and has an arc support section and a body section connected to the arc support section, and the rear end of the body section is It is cut into a conical shape, and the cut surface is configured to be close to the inner wall of the light emitting bulb.

[Effect]

Heat transfer via the starting gas in the bulb and radiant heat transfer from the back of the anode are carried out efficiently, so the part of the valve located behind the anode is easily warmed up, and the mercury behind the anode is quickly vaporized. .

Incidentally, if the above configuration is further combined with the use of a conventional heat-retaining film, the vaporization of mercury will be extremely rapid.

〔Example〕

FIG. 1 is an explanatory diagram of an embodiment of a short arc type high pressure mercury lamp according to the present invention.

In the figure, 1 is a light-emitting bulb surrounding a light-emitting space 2, and 3 is a cathode, the body of which is extended and also serves as a cathode internal lead rod 3a. Reference numeral 4 denotes an anode, which is made separately from the anode internal lead rod 5. The rear portion of the body portion 4b following the arc support portion 4a is cut off into a conical shape to form a cut surface 4c. 6 is a metal foil connected to the internal lead rod;
9 is an external lead rod. Reference numeral 10 denotes a branch pipe portion which cooperates with the metal foil to form an airtight structure and holds the internal lead rod. 11 is a glass pipe inserted as necessary.

Here, the cut surface 4c of the anode is designed as follows. That is, A-B is created by the intersection point A of the rearward extension line of the body and the inner wall of the bulb, and the intersection B of the line extending the rear end surface of the body laterally.
The cutting angle θ is determined so that it is approximately parallel to the line. In other words, the cut surface 4c is approximately parallel to the slope of a virtual truncated cone created by rotating the line A-B. Of course,
Although parallelism does not have to be satisfied, by doing so, the anode can be brought close to the valve,
This has the effect of uniformly warming the bulb part located behind the anode relatively widely. Naturally, this also has the effect of reducing the amount of mercury condensing behind the anode. Therefore, required electrical characteristics are easily achieved in short arc type high pressure mercury lamps that are lit with the anode positioned below.

To illustrate the electrical rating and anode dimensions, the power consumption
At 2KW, current is 54A, voltage is 37V, the starting gas is xenon 0.3 atm to 1 atm (25℃), and mercury is added in an amount that will be approximately 11 atm when the lamp is in use. Here, the anode is made of tungsten with a total length of 24 mm and a thickness of 12 mm.
The spherical protrusion distance supporting the arc is 6mm, the cutting surface is 4
The width of c is approximately 3 mm.

[Effect of idea]

As can be understood from the explanation of the above embodiments, in short arc type high pressure mercury lamps that are used for lighting with the anode positioned below, power consumption is increasing, the anode is becoming larger, and mercury escaping behind the anode is also increasing. This eliminates the disadvantages that arise when the number of mercury increases, as well as the disadvantages that it becomes increasingly difficult to raise the temperature of the bulb behind the anode and that the vaporization of mercury is delayed. We can provide short arc type high pressure mercury lamps.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of an embodiment of the short arc type high pressure mercury lamp of the present invention. In the figure, 1 is a light-emitting bulb, 2 is a discharge space,
3 is the cathode, 4 is the anode, 5 is the anode internal lead rod, 6
1 is a metal foil, 9 is an external lead rod, 10 is a branch pipe part, 1
1 indicates a glass pipe.

Claims (1)

[Utility Model Registration Claim] A short arc type high pressure mercury lamp comprising: a light-emitting bulb surrounding a discharge space and a branch tube section continuing to the tip of the light-emitting bulb; a cathode and an anode opposed to each other within the light-emitting bulb; and an internal lead rod supporting the cathode and anode and held in the branch tube section, wherein the anode is separate from the internal lead rod and has an arc support section and a body section continuing from the arc support section, the rear end of the body section being cut off in a conical shape with the cut surface adjacent to the inner wall of the light-emitting bulb and the anode positioned downward when lit.