JPH0542770B2 - - Google Patents

Description

[Detailed description of the invention]

TECHNICAL FIELD This invention relates to single-ended metal halide discharge lamps and methods of making the same, and more particularly to single-ended metal halide discharge lamps having a stabilized arc and a vessel configured for isothermal operation. BACKGROUND AND PRIOR ART In the field of projectors (projectors, projectors, magic lanterns, etc.), optical lens systems and similar devices that require relatively powerful light sources, it is customary to use light sources in the form of tungsten lamps. It was hot. Although tungsten or tungsten halogen lamps are inexpensive, have desirable characteristics such as desirable color properties to enhance skin tone, and do not require a special power source, some undesirable characteristics also exist. For example, structures using tungsten sources do not produce enough blue light and also tend to produce undesirably large amounts of heat, which requires the placement of expensive, complex cooling equipment adjacent to the light source. It also has the disadvantage of a relatively short lifespan, such as an operating time of about 10 to 20 hours. Therefore, it is not uncommon to replace the light source each time the device is used. clearly,
This is inconvenient and expensive, and therefore presents many problems. In addition, screen lighting is limited by the inability to increase surface brightness much above 3400㎓, while mechanical body structures are rigid and cannot be easily exposed during operation by chemical means and by vibration or shock. There is a risk of destruction. An improvement to the system described above has been made by using a metal halide discharge lamp as the light source. For example, a conventional type of high pressure metal halide discharge lamp is disclosed in US Pat. No. 4,161,672. In this U.S. patent, a double-ended arc tube, i.e., an arc tube with a pair of electrodes sealed at diametrically opposite ends, is used with an evacuated or noble gas-filled envelope. There is. However, such structures are relatively expensive to manufacture and are clearly not suitable for use in projectors or other optical lens type devices. U.S. Patent No. 4302699, No. 4308483, No.
No. 4,320,322, No. 4,321,501 and No. 4,321,504 disclose single-ended metal halide arc discharge lamps, all of which represent variations in construction or filling as appropriate for a particular device. As far as the stability of the arc and the isothermal uniformity of the discharge amplifier are concerned, both of the above US patents remain problematic. OBJECTS AND SUMMARY OF THE INVENTION It is an object of the invention to provide an improved single-ended high intensity discharge lamp. Another object of the invention is to improve the performance of single-ended high intensity discharge lamps. Another object of the invention is to provide a single-ended high intensity discharge lamp having an improved constructional configuration. Yet another object of the invention is to provide an improved method for manufacturing single-ended high intensity discharge lamps. In one aspect of the present invention, these and other objects, advantages and capabilities are accomplished by providing a metal rod and an oval shaped container each comprising a metal rod and an end of the metal rod sealed to one end and extending into the container. It has a pair of electrodes including a spherical ball in the
This is accomplished by a single-ended, high-pressure, high-intensity discharge lamp containing a metal-containing mercury filling within the vessel. In another aspect of the invention, a pair of electrodes, each having a spherical ball at the end of a metal rod, are sealed to one end of an oval shaped fused silica container;
A method is provided for manufacturing a single-ended metal halide discharge lamp in which the vessel is filled with mercury containing an unsaturated metal. DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to fully understand the present invention, as well as other objects, advantages, and capabilities of the present invention, preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings. Referring to FIG. 1, a low wattage metal halide lamp is illustrated having a body portion 5 of a material such as fused silica. The fused silica body portion 5 is formed to provide an elliptical inner portion 7 having a major axis (major axis) value X and a minor axis (minor axis) value Y in a ratio of approximately 2:1. Furthermore, the elliptical inner portion 7 of the body portion 5 preferably has a height Z substantially equal to the minor axis value Y. A pair of electrodes 9 and 11 are sealed to one end of the body portion 5 and extend into the body portion 5. Each electrode 9 and 11 includes a metal rod 13 and a spherical ball 15, the spherical ball 15 being at the end of the metal rod 13 within the elliptical inner portion 7 thereof. The electrodes 9 and 11 are arranged such that the ends of the spherical balls 15 of these electrodes 9 and 11 are substantially equally spaced from the inner part 7 insofar as the major axis X and the minor axis Y are concerned, and also that the height dimension Z is substantially Preferably, it is located within the inner part 7 of the oval shape, so as to be at the midpoint. A metal-containing mercury filling is also arranged within the elliptical inner part 7. For example, mercury doped with metal halides such as sodium and scandium along with argon is a suitable fill for low wattage metal halide discharge lamps.
Specifically, a 50W discharge lamp having an elliptical inner portion 7 with a volume of about 0.1 ^cm3 contains about 3.0 mg of mercury, 1.9 mg of sodium and scandium in a molar ratio of about 20:1, and about 200 torr of Filled with pressure argon. As a result of operation tests, the initial lumen output was approximately 3,100 lumens, and the luminous flux maintenance rate after 160 hours of operation was approximately 84%. Referring more particularly to the oval-shaped inner portion 7, FIG. electrode 9
and 11 are illustrated. As can be easily understood, the body portion 5 is preferably arranged vertically so that the spherical balls 15 are positioned one above the other. As a result, gas flow patterns 21 in FIG. 2 and 19 in FIG. 3 are generated, as shown by the arrows.
The cold gas tends to flow down the wall 17 of the inner part 7 and is drawn into the elliptical arc or plasma column 22 of the bottom electrode 11.
The spherical ball 15 of the bottom electrode 11 provides a spherical extension described below, and the spherical ball 15 of the bottom electrode 11
5 creates a constriction of the gas flow at the end of the arc, creating a bench lily effect 20. In this manner, arc termination wander is minimized. Also, the atoms of the gas are heated in the plasma column 22, and the upper electrode 9 acts as a deflector to spread out the hot gas reaching the top of the body portion 5 of the elliptical arc tube. Furthermore, during the operation of the arc tube, the wall 1
The infrared readings for temperature 7 are approximately 20 at a wall temperature of 1100℃.
% or less temperature change. Therefore, the elliptical inner portion 7 and the elliptical arc 22
provides a substantially uniform convective flow 21 of FIG. 2 without undesirable turbulence, thus providing arc stability, which is particularly important in projector and lens systems. It should also be noted that the arc tends to initially wander around the contact area of the spherical ball 15. However, it has been found that employing a seasoning step in the manufacturing process works to form protrusions 24 on each of the balls 15 as shown in the reference photograph. As a result, protrusion 24 serves to minimize the arc gap between spherical balls 15 of electrodes 9 and 11, causing the arc to have an endpoint located in the center of each of electrodes 9 and 11. The reference photograph above is a 100-fold enlargement of one electrode of the embodiment shown in FIG. Although not fully understood, it is believed that the protrusions 24 in the reference photo above have dimensions that depend on local material properties, electric field strength, and gas flow properties. Furthermore, growth appears to be a function of electrode size and temperature. Therefore, the lower the operating temperature, the longer the seasoning time required. As a specific example, approximately 0.017 inches with a ball 15 of approximately 0.025 inches.
A tungsten rod was operated in a 100W metal halide discharge lamp with a current of approximately 1.6A. After a seasoning phase of about 15 minutes under normal operating conditions, the arc stabilizes and one or more protrusions form the spherical balls 1 of electrodes 9 and 11.
It was found that it appeared on the surface of 5. Thus, the surface of the spherical ball 15 cracks into platelets and the protrusions thereby formed prevent any wandering of the arc and improve the light source. Moreover, it should be noted that arc sources such as metal halide discharge lamps are not only more bright than tungsten sources, but also more efficient. Also, metal halide discharge lamps are more like point sources than tungsten sources. When you specify,
A 100 watt metal halide discharge lamp has a minimum brightness between spherical balls 15 and 15 spherical balls.
The plasma exhibits maximum brightness at or near the position No. 5. Additionally, the plasma column typically has a diameter of about 1-2 mm and a length of about 3 mm. In contrast, the tungsten source has a diameter of about 25 mm and a length of about 8 mm.
mm, and the brightness varies sinusoidally over the length of the tungsten source. The following table shows a comparison of brightness, efficiency, and dimensions of tungsten sources, high pressure xenon sources, and metal halide lamp sources.

Table: As can be easily seen, a 300W tungsten source has an efficiency of approximately 33 lumens/watt compared to a 100W metal halide lamp's efficiency of 65 lumens/watt. Additionally, tests in a 35mm projection system showed that approximately
It was found that an output of 10,000 lumens is equivalent to an output of 6,500 lumens from a 100W metal halide lamp source. Long wavelength projections of tungsten sources and ill-directed visible light tend to be absorbed as heat by the projector's film. Thus, it has been found that a tungsten lamp source generates about 270 W of heat, or about three times as much heat, as compared to about 90 W of heat from a metal halide lamp and associated power source. Note that xenon lamp sources exhibit relatively high brightness, but relatively low efficiency. Therefore,
The need to compensate for the relatively inefficient lumen output of xenon sources, which is comparable to the lumen output provided by a 100W metal halide lamp.
A xenon source of approximately 200W is required. Additionally, the relatively small diameter of the xenon source, approximately 0.5 mm in this example compared to the approximately 1.0 mm diameter metal halide lamp arc source, makes the arc source This would undesirably reduce positional tolerances or variations to a large extent.
In other words, the adjustment of the position of the arc source in xenon lamps is much more critical than in metal halide discharge lamp systems. A single-ended metal halide discharge lamp was thus provided in which the electrodes were arranged within the elliptical inner part of the fused silica vessel. The interior of this oval shaped vessel provides substantially isothermal operating conditions for all parts of the fused silica vessel which together with the oval shaped arc form the discharge lamp. On top of that,
It has been found that a stable arc can be provided, which is particularly important for the operation of projectors and optical lens systems. Although what is presently considered to be the preferred embodiment of the invention has been illustrated and described, it is understood that various modifications and changes may be made thereto without departing from the invention as defined by the claims. This will be obvious to engineers in the field.

[Brief explanation of drawings]

1 is a schematic diagram illustrating an embodiment of a single-ended high-intensity discharge lamp of the present invention; FIG. 2 is a schematic cross-sectional diagram illustrating the discharge and convective gas flow for vertical operation of the discharge lamp of FIG. 1; Figure 3 is the first
FIG. 3 is a schematic diagram showing approximate lines of electric force between electrodes of the discharge lamp shown in the figure. 5: Lamp body part, 7: Oval inner part, 9, 11: Electrode, 13: Metal rod, 15:
Spherical ball, 22: Plasma column.

Claims (1)

Claims: 1. Forming a container of fused silica having an oval shape, each having a metal rod extending through the container and a spherical ball at an end of the metal rod within the container. filling the oval-shaped container with a high-pressure mercury filling with metal halide added thereto, the container being heated substantially uniformly; a single-ended metal halide discharge lamp, and further comprising: seasoning the discharge lamp for a period of time at a temperature sufficient to cause a protrusion in the spherical ball of the electrode. Method for manufacturing. 2. The method of claim 1, wherein the step of forming the elliptical shaped fused silica container is carried out in a manner such that the major and minor axes are in a ratio of about 2:1. 3. forming the elliptically shaped fused silica container is carried out in such a manner as to define a major axis and a minor axis, and the electrodes are in such a manner as to provide a substantially elliptically shaped arc between the electrodes; 2. The method of claim 1, wherein the method is sealed in the container along the longitudinal axis, and wherein the spacing between the elliptical arc and the elliptical container is substantially uniform. 4. The method of claim 1, wherein the elliptical container is filled with high-pressure mercury to which sodium and scandium are added. 5. A metal halide discharge lamp in which a pair of electrodes, each having a metal rod and a spherical ball fixed to the metal rod, are sealed at one end of a container, and a high-pressure mercury filling with metal halide is distributed into said container. In the method of manufacturing, the container is formed into an elliptical shape with major and minor axes in a ratio of about 2:1, such that each portion of the container can operate at substantially equal temperature; and A method of manufacturing a mehalide discharge lamp comprising the step of seasoning the discharge lamp for a period of time at a temperature sufficient to cause the spherical ball of the electrode to develop a protrusion.