BRIEF DESCRIPTION OF THE DRAWINGS
[FIG. 1] shows mode of embodiment 1, and it is a side surface view in partial section of the ultra-high-pressure mercury lamp 10;
[FIG. 2] shows mode of embodiment 1, and it is a cross-sectional view of the light-emitting tube 1;
[FIG. 3] shows mode of embodiment 1, and it shows brightness distribution data for the ultra-high-pressure mercury lamp 10 (150 W/1.0 mm (electrode gap));
[FIG. 4] shows mode of embodiment 1, and it is a plan view of the light-emitting tube 1;
[FIG. 5] shows mode of embodiment 1, and it is a plan view of the light-emitting tube 1;
[FIG. 6] shows mode of embodiment 1, and it shows the illuminance percentage when the electrode gap is unchanged and the electrodes have been moved; and
[FIG. 7] shows mode of embodiment 1, and it shows the illuminance percentage when an electrode on one side has been fixed, and an electrode on only one side has been moved.
BEST MODE FOR CARRYING OUT THE INVENTION
Mode of Embodiment 1
FIGS. 1 to 7 show mode of embodiment 1, where FIG. 1 is a side surface view in partial section of an ultra-high-pressure mercury lamp 10; FIG. 2 is a cross-sectional view of a light-emitting tube 1; FIG. 3 shows brightness distribution data for the ultra-high-pressure mercury lamp 10 (150 W/1.0 mm (electrode gap)); FIG. 4 and FIG. 5 are plan views of the light-emitting tube 1; FIG. 6 shows the illuminance percentage when the electrode gap is unchanged and the electrodes have been moved; and FIG. 7 shows the illuminance percentage when an electrode on one side has been fixed, and an electrode on only one side has been moved.
As shown in FIG. 1, in the ultra-high-pressure mercury lamp 10, the light-emitting tube 1 is fixed in the neck part 5a of a reflector 5 (concave reflective mirror) which comprises an open part 20 for the forward output of light, so that the optical axes match. A terminal 6a and a terminal 6b which are connected by a lead wire 4b from the electrode of the light-emitting tube 1 are arranged on the outer peripheral surface of the reflector 5. A trigger coil 7 is provided on the light-emitting tube 1 for causing the activation of the light-emitting tube 1.
As shown in FIG. 2, the light-emitting tube 1 comprises a bulb 8 made of quartz glass and a sealing part 2 formed along both sides of said bulb 8. The inside of the bulb 8 contains mercury, and part of the electrode 3a and the electrode 3b is sealed by the sealing part 2. A lead wire 4a and the lead wire 4b extend from the sealing part 2.
FIG. 3 shows brightness distribution data for the ultra-high-pressure mercury lamp (150 W/1.0 mm (electrode gap)). The X-axis shows the distance x (mm) in a straight line which links the pair of electrodes, taking the bulb center as 0, with the left side as + and the right side as −. The Y-axis is the distance y (mm) in the direction orthogonal to the straight line which links the pair of electrodes. The brightness values are relative, taking 100 as the maximum brightness.
As shown in FIG. 3, the position at which the brightness of the light-emitting tube 1 in the ultra-high-pressure mercury lamp 10 (150 W/1.0 mm (electrode gap)) is highest is not at the tip end of the electrode 3a and the electrode 3b, but several mm from the tip end of the electrode 3a and the electrode 3b toward the center. When the bulb center is taken as 0, this is the point +0.4167, 0.0833 mm from the tip end of the electrode toward the center on the left hand side of FIG. 3. This is the point −0.4167, 0.0833 mm from the tip end of the electrode toward the center on the right hand side of FIG. 3.
The light-emitting tube 1 is provided with the electrode 3a and the electrode 3b inside the bulb 8. The electrode 3a and the electrode 3b are normally arranged symmetrical to the bulb center 8a (solid line), but in this mode of embodiment, as shown by the broken line in FIG. 4, the electrode 3a and the electrode 3b are moved 0.1-0.4 mm to the right, for example. By virtue of this, if the electrodes are moved 0.4 mm, for example, the portion of highest brightness on the left hand side lies almost in the vicinity of the bulb center 8a, and it can be expected that the illuminance of the light radiated from the open part 20 of the ultra-high-pressure mercury lamp 10 will increase. Furthermore, since the electrode 3a and the electrode 3b are moved with each other, the electrode gap stays at 1.0 mm, and therefore it is thought that there is little risk that the mercury pressure will fail to rise and that the electrical power of the lamp will drop because of a drop in the lamp voltage.
Furthermore, as shown in FIG. 5, the electrode 3a and the electrode 3b may be moved 0.42 mm to the left, for example. By virtue of this, the portion of highest brightness on the right hand side lies almost in the vicinity of the bulb center 8a, and it can be expected that the illuminance of the light radiated from the open part 20 of the ultra-high-pressure mercury lamp 10 will increase. In the same way as in FIG. 4, since the electrode 3a and the electrode 3b are moved with each other, the electrode gap stays at 1.0 mm, and therefore it is also thought that there is no risk that the mercury pressure will fail to rise and that the electrical power of the lamp will drop because of a drop in the lamp voltage.
FIG. 6 shows the results obtained from a simulation of the illuminance of the ultra-high-pressure mercury lamp 10 (150 W/1.0 mm) having the configuration shown in FIGS. 4 and 5. FIG. 6 also shows the results using an ultra-high-pressure lamp 10 (250 W/1.3 mm). In FIG. 6, the X-axis shows the electrode shift (electrode movement distance, units: mm), and the Y-axis shows relative illuminance values, taking the illuminance (illuminance on a 40 inch projector screen) when the electrode 3a and the electrode 3b are not moved as 100. Furthermore, the illuminance percentage is the average value of the illuminance when the electrode 3a and the electrode 3b are moved to the left and when they are moved to the right.
In the case of the ultra-high-pressure mercury lamp 10 (150 W/1.0 mm), when the electrode gap is unchanged and the electrode 3a and the electrode 3b are moved with each other by 0.1 mm, the illuminance increases by approximately 0.3%. Furthermore, in the same way, when the electrode 3a and the electrode 3b are moved with each other by 0.2 mm, the illuminance increases by approximately 5%. Furthermore, in the same way, when the electrode 3a and the electrode 3b are moved with each other by 0.3 mm, the illuminance increases by approximately 10%. Furthermore, in the same way, when the electrode 3a and the electrode 3b are moved with each other by 0.4 mm, the illuminance increases by approximately 20%.
In the case of the ultra-high-pressure mercury lamp 10 (250 W/1.3 mm), when the electrode gap is unchanged and the electrode 3a and the electrode 3b are moved with each other by 0.1 mm, the illuminance increases by approximately 0.2%. Furthermore, in the same way, when the electrode 3a and the electrode 3b are moved with each other by 0.2 mm, the illuminance increases by approximately 1.3%. Furthermore, in the same way, when the electrode 3a and the electrode 3b are moved with each other by 0.3 mm, the illuminance increases by approximately 3.5%. Furthermore, in the same way, when the electrode 3a and the electrode 3b are moved with each other by 0.4 mm, the illuminance increases by approximately 8%. Furthermore, in the same way, when the electrode 3a and the electrode 3b are moved with each other by 0.5 mm, the illuminance increases by approximately 13%. Furthermore, in the same way, when the electrode 3a and the electrode 3b are moved with each other by 0.6 mm, the illuminance increases by approximately 20%.
FIG. 7 shows the illuminance percentage when an electrode is fixed on one side, and an electrode on only one side has been moved. As shown in FIG. 7, in this case also, results virtually the same as those for FIG. 6 have been obtained. Accordingly, the illuminance of the light radiated from the open part 20 of the ultra-high-pressure mercury lamp 10 can be increased, even if an electrode is fixed on one side and an electrode on only one side is moved, within the range where the mercury pressure does not rise and the electrical power of the lamp does not drop because of a drop in the lamp voltage.
As can be seen from the above, it is possible to increase the illuminance of the light radiated from the open part 20 of the ultra-high-pressure mercury lamp 10 by bringing one electrode of the ultra-high-pressure mercury lamp 10 closer to the bulb center 8a or by making it conform therewith. In this case, the other electrode may be moved in the same manner as the first electrode so that the electrode gap does not change, or it may be fixed. However, if the electrode gap becomes smaller, the mercury pressure may not rise and the electrical power of the lamp may drop because of a drop in the lamp voltage, and therefore it is preferable for the electrode gap not to change too much.
Patent Application
20080018253
