a) to 2(c) each show a schematic of the metal foil according to a first embodiment of the invention,
a) and 4(b) are, respectively schematic plan and longitudinal sectional views of the metal foil according to a second embodiment of the invention;
a) and 6(b) each show a schematic of the action of a first embodiment of the invention;
a) and 7(b) each show a schematic of the action of a second embodiment of the invention;
a) to 8(c) each show a schematic of a conventional electrode mount assembly and a conventional metal foil;
a) to 9(c) each show a schematic illustrating the disadvantage which arises in a conventional ultra high pressure mercury lamp, and
a) and 10(b) each show a schematic illustrating the disadvantage which arises in a conventional ultra high pressure mercury lamp.
The amount of mercury added is at least 0.15 mg/mm3 so that the mercury vapor pressure in the interior S during operation is at least 150 atm. However, an amount of added mercury of at least 0.2 mg/mm3 is especially advantageous since it enables an ultra high pressure mercury lamp with a high mercury vapor pressure to be produced. The amount of the halogen gas added is in the range from 3.0×10−4 μmol/mm3 to 7.0×10−3 μmol/mm3. The amount of added buffer gas is in the range from 10 kPa to 20 kPa.
In each hermetically sealed portion 12, a metal foil 4 of molybdenum is hermetically installed by shrink sealing for purposes of power supply. Base parts 22A, 32A of the upholding part of the electrode 22, 32 are connected to the ends of the metal foils 4. The end of the outer lead 5 for power supply is connected to the base part of the metal foil 4. The base part of the outer lead 5 projects to the outside from the hermetically sealed portion 12.
Such an ultra high pressure mercury lamp is operated using an alternating current which supplies the electrodes 2, 3 with current from an alternating current source (not shown) and which is connected to the outer leads 5. A high voltage is applied between the electrodes 2 and 3 by the alternating current source. An insulation breakdown forms between the electrodes 2, 3. Light which contains wavelengths of visible radiation of 360 nm to 780 nm is emitted from the light emitting part 11.
a) to 2(c) each schematically show the metal foil according to the first embodiment of the invention.
As is shown in
The depth of the end groove 46, as is shown in
The depth of the base-side groove 47, as shown in
Because such an end groove 46 and such a base-side groove 47 are attached, for the wide region 42, the end Ω-region 42A with an Ω-shaped cross section borders the region with the small width 41. Furthermore, the middle, flat region 42B is closer to the base side of the wide region 42 than to the end Ω-region 42A and the base-side Ω-region 42C with an Ω-shaped cross section is nearer the base side of the wide region 42 than the middle flat region 42B. This means that, between the end Ω-region 42A and the base-side Ω-region 42C, there is a middle flat region 42B.
In the electrode end mount assembly 20 according to the first embodiment, the outside diameter of the outer lead 5 and the outside diameter of the base part 22A of the upholding part of the electrode 22 are identical to one another. In the electrode end mount assembly 20, the center axis of the base part 22A of the upholding part of the electrode 22 is in the same plane as the flat part 420A in the end Ω-region 42A and the center axis of the outer lead 5 is in the same plane as the flat part 420C of the base-side Ω-region 42C. In this way, the center axis of the base part 22A of the upholding part of the electrode 22 agrees with the center axis of the outer lead 5.
The numerical values of the above described electrode 2, the above described metal foil 4 and the above described outer lead 5 are cited below using one example.
For the upholding part of the electrode 22, the total length in the lengthwise direction which is parallel to the center axis is in the range from 4 mm to 10 mm and the outside diameter of the base part 22A is in the range from 0.3 mm to 0.5 mm.
For the outer lead 5, the total length in the lengthwise direction which is parallel to the center axis is in the range from 30 mm to 50 mm and the outside diameter is in the range from 0.5 mm to 0.8 mm.
For the metal foil 4, the total length is in the range from 14 mm to 21 mm and the thickness is in the range from 0.015 to 0.02 mm. In the region with a small width 41, the total length in the lengthwise direction which is parallel to the center axis is 3 mm and the total length in the direction of width which orthogonally intersects the center axis is in the range from 0.3 mm to 0.6 mm. The weld length of the base part 22A of the electrode in the region with a small width 41 of the metal foil 4 is in the range from 1.3 mm to 1.7 mm. In the wide region 42, the total length in the lengthwise direction which is parallel to the center axis is in the range from 11 mm to 18 mm and the total length of the direction of width which orthogonally intersects the center axis is in the range from 1.2 mm to 1.8 mm.
For the end groove 46, the total length in the lengthwise direction which is parallel to the center axis is in the range from 3 mm to 6 mm and the total length of the direction of width which orthogonally intersects the center axis is in the range from 0.3 mm to 0.6 mm. Furthermore, the total length of the lengthwise direction of the end side bottom surface 46A which forms the bottom surface of the end Ω-region 42A, which lengthwise direction is parallel to the center axis, is in the range from 1 mm to 2 mm and the total length of the lengthwise direction which is parallel to the center axis of the end bevel 46B is in the region from 2 mm to 4 mm.
For the base-side groove 47, the total length of the lengthwise direction which is parallel to the center axis is in the range from 4 mm to 6 mm and the total length in the direction of width which orthogonally intersects the center axis is in the range from 0.3 mm to 0.6 mm. Furthermore, the total length of the lengthwise direction of the end side bottom surface 47A which forms the bottom surface of the end Ω-region 42C, which lengthwise direction is parallel to the center axis, is in the range from 1.7 mm to 2.3 mm and the total length of the lengthwise direction which is parallel to the center axis of the end bevel 47B is in the region from 2 mm to 4 mm. The weld length of the outer lead 5 on the bottom-side bottom surface 47 is in the region from 1.7 to 2.3 mm.
In the middle flat part 42B, the total length in the lengthwise direction parallel to the center axis is in the range from 3 mm to 6 mm.
A second embodiment of the ultra high pressure mercury lamp in accordance with the invention is described below.
In the metal foil 4 shown in
The ultra high pressure mercury lamp according to the second embodiment of the invention is directed toward the recent trend toward reducing the size of the lamp, and thus, also the size of the electrodes. Furthermore, the electrodes must tightly adjoin the glass of the hermetically sealed portion. If the electrode diameter in the region adjoining the glass is large, the adhesive property on the silica glass is insufficient, so that the construction is such that the outside diameter of the base part 22A of the upholding part of the electrode 22 which is connected to the metal foil 4 is 0.3 to 0.5 mm.
On the other hand, the outer lead 5 constitutes a location which is exposed to the atmosphere. Sufficient mechanical strength must be ensured to prevent its breaking upon oxidation. The outside diameter is therefore 0.5 mm to 0.8 mm. It is generally built such that its diameter is larger than that of the base part 22A of the upholding part of the electrode 22.
The end mount assembly 20 is arranged in the manner described below to bring the center axis of the upholding part of the electrode 22 into agreement with the center axis of the outer lead 5.
For the one-sided groove 48 which extends over the end region with the small width 41 and of the wide region 42, its depth agrees with the radius of the base part 22A of the upholding part of the electrode 22. Furthermore, the depth of the base-side groove 49 agrees with the radius of the outer lead 5 on the base side of the wide region 42.
In the electrode end mount assembly 20 shown in
The action of the above described ultra high pressure mercury lamp is described below using
a) and 6(b) each show the action of the first embodiment in which the outside diameter of the outer lead 5 is identical to the outside diameter of the base part 22A of the upholding part of the electrode 22.
As was described above, when the electrode end mount assembly 20′ is inserted into the silica glass tube 10′, the electrode mount assembly 20′ is angled toward the center axis of the silica glass tube 10′, as shown in
By using the metal foil 4 in accordance with the invention, in the above described case of an arrangement of the upholding part of the electrode 22 which is eccentric from the center axis of the silica glass tube 10′, it does not happen that the region of the metal foil 4 with a small width 41 is bent. The reason for this is the following:
The middle, flat region 42B is attached in the metal foil 4 in accordance with the invention, by which a load on the surface 22X of the upholding part of the electrode 22 which is adjacent to the silica glass is absorbed in the direction of the center axis of the silica glass tube 10′, when this force is applied. In this way, the middle, flat region 42B is bent, by which concentration of the load on the region with a small width 41 is prevented. As is shown in
The middle, flat region 42B is bent by the above described loading. Since, in the region with the small width 41, in the vicinity of the interior S, the adhesive property on the silica glass is ensured, however, it does not happen that a high mercury vapor pressure in the interior S is acting in operation. Therefore, there is no danger of cracking in the silica glass in the vicinity of the middle, flat region 42B.
Conversely, if a conventional metal foil with an Ω-cross section is used over the entire length of the wide region 42′, as is shown in
a) and 7(b) each show the second embodiment in which the action is shown in the case in which the outside diameter of the outer lead 5 differs from the outside diameter of the base part 22A of the upholding part of the electrode 22.
As is shown in
Therefore, for the above described reason, it never happens that for the metal foil 4 is bent to a large extent in the region with the small width 41, as is shown in
Furthermore, in the case of producing the electrode-mount assembly 20 using the upholding part of the electrode 22 and the outer lead 5 with different outside diameters, the electrode mount assembly 20 is inserted angled relative to the center axis of the silica glass tube 10′. Therefore, there is the danger that the upholding part of the electrode 22 will be arranged eccentrically to the center axis of the silica glass tube 10′. In this case, as was described above, the load which is applied to the upholding part of the electrode 22 to move the upholding part of the electrode 22 in the direction of the center axis of the silica glass tube 10′ during shrink sealing is, of course, absorbed by the middle, flat region 42B so that neither bending of the region with a small width 41 of the metal foil 4 nor cracking occurs in the hermetically sealed portion 12.
In the ultra high pressure mercury lamp in accordance with the invention, besides the aforementioned action, the following action can also be obtained.
Since the base part 22A of the upholding part of the electrode 22 is wound with the region with the small width 41 with a U-shaped cross section, between the metal foil 4 and the base part of the upholding part of the electrode 22, there is never a gap. Therefore, cracks in the hermetically sealed portion 12 as a result of the action of a high mercury vapor pressure of the interior S on the gap between the metal foil 4 and the base part 22A of the upholding part of the electrode 22 during operation can be reliably prevented.
Since both the region with a small width 41 and also the base-side Ω-region 42C are attached in the metal foil 4, the upholding part of the electrode 22 and the outer lead 5 can be suitably positioned with respect to the metal foil 4.
In the metal foil 4, the end groove 46 and the base-side groove 47 are formed, for example, by embossing using a stamping die such that they are positioned essentially on a straight line. In this way, the region with a small width 41 with an Ω-shaped cross section and a groove-shaped overall form, and the base-side Ω-region 42C, are formed beforehand. If the upholding part of the electrode 22 and the outer lead 5 are connected to the region with a small width 41 and the base-side Ω-region, and thus, the electrode end mount assembly 20 is formed, the center axis of the base part 22A of the upholding part of the electrode 22 can be brought into agreement with the outer lead 5.
There is the advantage that, by the arrangement of the end Ω-region 42A, the mechanical strength of the metal foil 4 is increased, even if the end Ω-region 42A is not connected to the base part 22A of the upholding part of the electrode 22. In this way, there is no danger that the metal foil 4 will break in transport as compared to a completely flat metal foil, or similar problems. Furthermore, because the shape of the metal foil 4 of the electrode end mount assembly 20 is stably maintained, the electrode end mount assembly 20 is more easily inserted into the silica glass tube 10′.
Furthermore, since the end groove 46 (48) has an end bevel 46B (48B) bordering the end bottom surface 46A (48A), such that it gradually reduces its depth in the direction toward the base side of the wide region 42, the groove depth changes only slowly. The danger of formation of folds in the metal foil 4 during the shrink sealing is thus eliminated. As a result, the adhesive property of the metal foil 4 on the silica glass can be ensured in its vicinity. For the same reason, a base-side bevel 47B borders the base-side groove 47 (49).
In accordance with the invention, it is not necessarily precluded that the middle flat region 42B will border the base side of the end Ω-region 42A or that the middle flat region 42B will border the end side of the base-side Ω-region 42C. It was described above that, in accordance with the invention, the arrangement of the end bevel 46A (48A) in the end groove 46 (48) or the arrangement of the base-side bevel 47A (49A) in the base-side groove 47 (49) is best. However, a configuration is also possible without this.
In the above described embodiment, an ultra high pressure mercury lamp of the alternating current operation type is described. However, the invention can also be used for an ultra high pressure mercury lamp of the direct current operation type. Furthermore, the invention can also be used for a mercury lamp with a smaller amount of added mercury than in the above described ultra high pressure mercury lamp. Also, the invention can be used for other discharge lamps, such as a metal halide lamp and the like with emission substances which do not contain mercury.
Number | Date | Country | Kind |
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2006-159932 | Jun 2006 | JP | national |