JPS6290843A - High-pressure discharge lamp - Google Patents

Abstract

PURPOSE:To avoid acoustic resonance and enable to maintain stable illumination by making high frequency lighting, by means of a frequency modulation process, of a high-pressure discharge lamp made up of an illumination tube which has curved surface part where the ends of the tube are flared from the electrode sealing ends toward the middle of the illumination tube. CONSTITUTION:An illumination tube is made to have a curve surface part where the ends of the tube are flared from the electrode sealing ends toward the middle of the illumination tube. The illumination tube is used as a high- pressure discharge lamp to be lighted with high frequency by means of a frequency modulation process. The radius of curvature of the curved surface part of this illumination tube divided by the inner diameter of the tube is made greater than zero. Mercury vapor density is kept below 7.5mg/cm<2> with arc column electric field intensity kept below 40V/cm and power consumption per unit volume of arc column kept below 350W/cm<2>. The tube end is shaped so that the electrode sealing end is located off the center axis of the illumination tube. The high-pressure discharge lamp thus constructed is lighted with high frequency by means of a frequency modulation process, to avoid acoustic resonance of the discharge lamp and to maintain stable illumination.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a high-pressure discharge lamp that is operated at high frequency.

(Background Art) FIG. 1 shows an example of a conventional high-pressure discharge lamp, in which electrodes 2a and 2b are disposed facing each other at both ends of an arc tube 1 made of quartz glass or the like. is the sealing part 3a,
It is connected to metal foils 4a and 4b, such as molybdenum foil, sealed in 3b. The metal foils 4a and 4b are connected to support conductors 5a and 5b which also serve as support for the arc tube 1.
are fixed to the support conductors 5a, 5b via fixing jigs 6a, 6b. Support conductors 5a and 5b are connected to an external circuit via a base 7. In addition, an appropriate amount of rare gas and a luminescent substance are sealed inside the arc tube 1, and an outer tube 8 that covers the arc tube 1 is provided.
Gas is sealed inside, and the inner surface of the outer tube 8 is coated with a fluorescent substance 9.

When such a conventional high-pressure discharge lamp is lit with a high-frequency power source, there are advantages in that the luminous efficiency is improved, and the ballast can be made smaller and lighter, and its loss can be reduced by electronicizing the lighting circuit. However, on the other hand, it has the disadvantage that an acoustic resonance phenomenon occurs at a specific frequency determined by the speed of sound in the arc tube and the shape of the arc tube, causing curvature, fluctuation, and extinction of the arc column, and destruction of the arc tube.

In order to turn on the lamp stably, select a frequency range in which the high-pressure discharge lamp can turn on stably.
(Refer to Publication No. 971) However, the frequency range for stable lighting varies depending on the type of lamp, and even for the same type of lamp, there are variations between individual lamps, so it is difficult to set a specific frequency. was difficult.

Also, high-frequency lighting at a frequency of 100 kHz or more, DC lighting (see, for example, Japanese Patent Application Laid-Open No. 57-61295), and square wave lighting (see, for example, Japanese Patent Application Laid-Open No. 57-61294).
Alternatively, methods have been proposed to avoid the acoustic resonance phenomenon by lighting at high frequencies using a frequency modulation method (for example, Japanese Patent Laid-Open No. 56-48095), but such lighting methods require complicated circuit configurations and radiated radio noise. There are problems such as occurrence.

(Object of the invention) The present invention was made in order to eliminate the above-mentioned drawbacks.
Its purpose is 5. To provide a high-pressure discharge lamp in which unstable arc is not generated in the arc tube due to acoustic resonance phenomenon during high-frequency lighting.

(Disclosure of the Invention) The present invention provides a high-pressure discharge lamp having an arc tube in which the tube end shape has a curved surface section that widens from the electrode-sealed end (tube end top) toward the center of the arc tube. Alternatively, a high-pressure discharge lamp with an arc tube formed such that the electrode-sealed end (the top of the tube end) is located off the center axis of the arc tube is lit at high frequency using a frequency modulation method. It is characterized by avoiding the acoustic resonance phenomenon that sometimes occurs.

First, the acoustic resonance phenomenon will be explained. Acoustic resonance is a resonance phenomenon that occurs when a standing wave is created when the natural frequency determined by the arc tube shape and the enclosed material matches the pressure fluctuation within the arc tube due to time changes in input power.

Assuming that the arc tube has a cylindrical shape, the cylindrical coordinate system (r.

θ, z). Note that r is the radial direction, θ is the circumferential direction, and 2
represents the coordinate in the axial direction. In such a case, the fundamental frequencies Fr, Fθ, Fz of the resonance phenomenon in each of the above directions are as follows.

r direction resonance: F r =3.83C/ (2WR)θ
Directional resonance: Fθ = 1.84C/ (2πR) Two-way resonance: F z =C/ (2L) where L is the arc tube length.

R is the radius of the arc tube.

C is the sound velocity inside the arc tube, which is determined by the inclusions inside the tube and the blackness inside the tube.

C-JT] Co-77 γ Constant pressure specific heat/constant volume specific heat P = Gas constant T = Temperature inside the arc tube M - Average atomic weight of the enclosed substance And a resonance phenomenon occurs at a frequency that is an integral multiple of this fundamental frequency. When an acoustic resonance phenomenon occurs, the force generated by the resonance phenomenon overcomes the force of the arc column itself to maintain stable discharge, causing the arc column to deform.

Therefore, the present inventors fabricated prototype high-pressure discharge lamps with various arc tube shapes, and investigated whether acoustic resonance phenomenon occurred by lighting these lamps with various high-frequency lighting methods, and found the following. It has been found.

Generally, when high-frequency lighting is performed, the lighting is performed while avoiding the audible frequency range. Furthermore, if the lamp is turned on at a frequency of 100 KHz or higher, radiated radio noise will be generated, causing a problem. Therefore, the lighting method is 20KIIz or less and 100KILz.
When lighting was performed using a frequency modulation method in a region that does not include the above frequencies, it was found that specifying the shape of the arc tube is effective in avoiding acoustic resonance phenomena. Figure 2 is a circuit diagram showing an example of a high pressure discharge lamp lighting device used in such experiments.
In the figure, DC is a direct current power supply, FM is a frequency modulation signal generator,
SW is a switching element, Z is a current limiting element, LA is a high pressure discharge lamp, and CO is a capacitor.

Next, when 250W high-pressure discharge lamps with various arc tube shapes were lit using the lighting method described above, it was found that the shape of the end of the arc tube in the tube axis direction (hereinafter referred to as the tube end) has a large relationship with the acoustic resonance phenomenon. It turns out that there is. That is, it has been found that the acoustic resonance phenomenon can be avoided if the tube end shape is substantially flat (Japanese Patent Application No. 59-265052).

Furthermore, as a result of various studies focusing on the shape of the tube end, we found that the tube end has a curved surface that expands from the electrode-sealed end toward the center of the arc tube. When a high-pressure discharge lamp, or a high-pressure discharge lamp whose arc tube is formed such that the electrode sealing end is located off the center axis of the arc tube, is lit at high frequency using the variable frequency JjM method, an acoustic resonance phenomenon occurs. It was found that the avoidance effect was significant.

The present invention has been made based on the above discovery, and will be described in more detail below based on Examples.

Among various arc tube shapes, the cylindrical shape is the easiest to manufacture, and the experimental results using various high-pressure discharge lamps with various shapes and dimensions of the tube end are shown in Figures 3 and 4. Compare and show. In addition, in FIG. 3 and FIG. 4, the horizontal axis is the center frequency [K Ilz ] of the lighting frequency, and the vertical axis is the frequency modulation width [KHz]. Further, an x mark indicates a case where an acoustic resonance phenomenon occurs, and an O mark indicates a case where an acoustic resonance phenomenon does not occur.

Fig. 3 (al indicates a conventional example, the tube end shape is approximately spherical, and the curved surface dimension Lr1 (see Fig. 5 + a)) is approximately 1
This is a case of drunkenness. From the figure, it can be seen that in the conventional example, it is almost impossible to avoid the acoustic resonance phenomenon. Fig. 3 (bl is a tube whose end shape is approximately spherical, and the curved surface dimension Lr1 is 6 mm, which is approximately half of the conventional example, and is closer to a flat shape. In this case, the acoustic resonance phenomenon can be avoided. The area where the tube ends are approximately twice as large as that of the conventional example, demonstrating the effect of making the tube end shape nearly flat.Next, the area shown in FIG. Dimension Lrz (
This is an experimental result when changing the temperature (see FIG. 5 fb)). The curved surface dimension Lr2 is (at: Omm,
(bl: 6 mm, (cl: 9 mm). Here, in the case shown in (bl) in the same figure, the curved surface dimension is 6 mm as in the case shown in Fig. 3 (bl), but the tube end shape is The shape is not spherical, but has a curved surface that spreads from the electrode sealing end toward the center of the arc tube, for example, I'
ll It is shaped like a bell. In this case, the area in which the acoustic resonance phenomenon can be avoided is further expanded, and it can be seen that the acoustic resonance phenomenon can be avoided in almost the entire area.

Also, as is clear from Figure 4, the center frequency is 30K.
llz ~60K Hz, frequency modulation width 0K) Iz-1
It can be seen that in the 0KIIz region, there is a large difference in the effect of avoiding the acoustic resonance phenomenon due to the difference in the dimensions of the curved surface of the tube end.

Therefore, if we look at these relationships in terms of the curved surface dimensions and the acoustic resonance phenomenon occurrence region (hereinafter referred to as the unstable region),
The result is as shown in FIG. In other words, the horizontal axis represents the curved surface dimension/pipe inner diameter, and the vertical axis represents the unstable area ratio (center frequency 30KHz to 60KHz, frequency modulation width 0KIIz to 1
The ratio of unstable region in the region of 0 Kllz) is taken. Note that the x mark shown in Figure 6 (the ratio of unstable region is approximately 1)
00% position) relates to the conventional example shown in FIG. 3 (al).

Here, it is clear from Fig. 6 that the limit for avoiding the acoustic resonance phenomenon is set at 50% (preferably 40%) in terms of the proportion of the unstable region, taking into account the variations between individual lamps and the variations in circuit constants. As such, the limit of the curved surface dimension/pipe inner diameter is "0 or more", preferably ro, 07 or more.

Note that FIG. 5 fat shows the shape and dimensions of the arc tube used in FIG. 3, and FIG. 5(b) shows the shape and dimensions of the arc tube used in FIG. 4. The dimensions are as follows.

Pipe inner diameter D: 15 mm Curved surface dimension Lr1 Fig. 3 (as shown in al: 11 mm Fig. 3 (as shown in bl: 6 mm) Curved surface section dimension Lr2 Fig. 4 (as shown in al = 01 Fig. 4 (as shown in bl) 6mm Figure 4 (Thing shown in C1 = 9mm Distance between electrodes Ll) 755mm Next, the curved surface that spreads from the electrode sealing end toward the center of the arc tube does not need to exist around the entire circumference of the arc tube. No, 7th
It may be a part as shown in the figure. With such a shape, the pipe inner diameter D = 18 mm and the curved surface dimension Lr5 = 1 inch +
FIG. 8 shows the results of lighting a high-pressure discharge lamp equipped with an arc tube with an electrode distance Lp of 35 mm. In this case, the percentage of unstable regions was 46%.

Furthermore, the spread of the curve from the electrode sealing end toward the center of the arc tube does not necessarily have to be concave as shown in FIG. 5(b), but may be concave as shown in FIG. 9 (al, mountain). It may also be a combination of convex shapes.

Note that the above experimental results are data when the high-pressure discharge lamp is lit vertically, but in general, when the lamp is lit horizontally, the buoyant force acting on the arc acts as a stabilizing force, so the arc is not affected by the acoustic resonance phenomenon. Deformation is less likely to occur than in the case of vertical lighting, and therefore the present invention is effective regardless of the lighting direction (vertical, horizontal, tilted). Actually, when the high-pressure discharge lamp used in the vertical lighting experiment shown in FIG. 8 is turned on horizontally, the results shown in FIG. 10 are obtained, and the ratio of the unstable region is reduced to 36%.

Further, according to the present invention, it is possible to make the curved surface part of the tube end longer, which is advantageous in sufficiently promoting the evaporation of the substance sealed in the tube. At the same time, this is advantageous in the case of a metal halide lamp containing a metal halide.

Next, when we applied the above to a small high-pressure discharge lamp of 250W or less, we found that the shape of the end of the arc tube was changed to widen from the electrode-sealed end toward the center of the arc tube, as in the case of 250W. It has become clear that the acoustic resonance phenomenon can be avoided by forming the device to have a curved surface portion.

Generally, in small high-pressure discharge lamps of 250 W or less, the arc tube shape is shown in Figure 11 in order to increase the load on the tube wall and raise the temperature of the tube end to promote evaporation of the enclosed luminescent material. It has a spherical or elliptical shape. However, when a high-pressure discharge lamp having a spherical tube end cross-sectional shape as described above is operated at a high frequency, acoustic resonance phenomena frequently occur. In order to avoid this, the dimensions of the curved surface of the pipe end should be set to 3n+m±2mm.
In the case of small high-pressure discharge lamps, it is difficult to maintain the tube end at a high temperature, and the luminescent material enclosed in the lamp does not evaporate sufficiently, resulting in a decrease in luminous efficiency.
There were drawbacks such as uneven emission color.

Therefore, as shown in FIG. 12, if the tube end shape is formed to have a curved surface section that expands from the electrode-sealed end toward the center of the arc tube, it is acceptable to avoid the acoustic resonance phenomenon. The dimension of the curved surface of the tube end need only be 0 mm or more, and it can be made as long as desired, keeping the tube end temperature at a high temperature, without reducing the luminous efficiency, and causing uneven luminescence color. This makes it possible to avoid acoustic resonance phenomena without any problems.

Note that the insertion position of the electrode does not necessarily have to be at the end of the tube; for example, it may be of a so-called single-end type, in which the electrode is inserted at the center of the arc tube as shown in FIG.

Next, the second invention will be explained.

The one shown in FIG. 14 fa) is according to the present invention, in which the tube end shape of the arc tube shown in FIGS. In contrast, the electrode sealing end (tube end apex) is formed to be located off the central axis of the arc tube, and the curved surface dimension Lr2 (Fig. 15) ta+) is set to 61 as in FIG. 3 ta). In this case, it can be seen that the area in which the acoustic resonance phenomenon is avoided is further expanded.

Furthermore, the curved surface dimension of the one shown in Fig. 14 fbl is 9 mm.
However, the same effect is obtained.

In the present invention, there are three ways in which the electrode sealing end may be unevenly distributed from the central axis of the arc tube, as shown in FIGS. 16 (al to C1). This corresponds to the case of FIG. 16(b).Therefore, as a different example, the curved surface portion dimension Lr2 corresponds to FIG. 16 ta+.
FIG. 17 shows the experimental results when (FIG. 15 (see BL)) is 9 mm. From the same figure, it can be seen that the effect is almost the same as that of FIG. 14 (a) and (BL).

Therefore, regardless of how the electrode sealing end is unevenly distributed from the central axis of the arc tube, it can be said that as long as it is unevenly distributed, there is an effect of preventing the acoustic resonance phenomenon.

Note that even if the surface connecting the electrode sealing end and the arc tube is formed into a curved surface, it may be formed into a flat surface (as shown in FIG. 16 (dl, (el)).
It may be an eccentric conical shape), and it is sufficient that it is unevenly distributed. Also, the tip of the tube end does not need to be sharp;
It may be flat as shown in Figure 6 (el, (f)).

As a further different embodiment, consider a case where one tube end shape is the shape of the present invention and the other tube end shape is spherical like the conventional example. FIG. 18 shows the experimental results when such an arc tube-shaped lamp was lit vertically. 18th
The one shown in Figure +a) is when the tube end shape of the present invention is the lower end, and the one shown in Figure 18 (bl) is when the spherical tube end is the lower end. C1) is 6 mn+.As is clear from the figure, in the case of vertical lighting, if at least the lower end has the shape according to the present invention, it can be said that there is an effect of preventing acoustic resonance phenomenon. Similarly to the first invention, the lighting direction (
It can be said that it is effective regardless of whether it is vertical, horizontal, or tilted.

Note that Figure 15 (al) is the one used in Figure 14 (al) and Figure 14 (bl), Figure 15 (b) is the one used in Figure 17, and Figure 15 (C) is the one used in Figure 14 (al) and Figure 14 (bl). This is the one used in FIG.

The dimensions are as follows.

Pipe inner diameter D: 15 mm Curved surface dimension Lr2 As shown in Figure 14 (a): 61 As shown in Figure 14 (bl): 9 mm As shown in Figure 17: 9 mm As shown in Figure 18: 6ff111! Distance between electrodes L+
): 55mm Next, when we applied the above to a small high-pressure discharge lamp of 250W or less, we found that, as in the case of 250W, we changed the tube end shape of the arc tube so that the electrode sealed end was deviated from the center axis of the arc tube. It has become clear that the acoustic resonance phenomenon can be avoided by forming the filter so that it is located at a certain location.

Therefore, as shown in FIGS. 19 and 20, if the shape of the tube end of the arc tube is configured such that the electrode sealing end is located off the center axis of the arc tube, the tube end Since the dimension of the curved surface part can be made long, it has become possible to maintain the temperature of the tube end at a high temperature and avoid acoustic resonance phenomena without reducing the luminous efficiency or producing uneven luminescent color.

In addition, in the present invention, as in the first invention, it is possible to make the curved surface part of the tube end longer, which is advantageous in sufficiently promoting the evaporation of the substance sealed in the tube, and in particular, This is advantageous in the case of a metal halide lamp in which a metal halide is sealed in the tube at the same time as mercury and rare gas.

Next, we examined the water 11M airtight density, arc column electric field strength, and power consumption per unit volume in the arc column during lighting operation, and found that limiting each value to below a predetermined value will reduce the acoustic resonance phenomenon. It turns out that avoidance is more effective.

First, the mercury vapor density during lighting operation will be described. The acoustic resonance phenomenon occurs because ions accelerated by an electric field collide with neutral atoms, causing pressure fluctuations, and when the resonance frequency of the arc tube matches the frequency of the pressure fluctuations, a standing wave is generated. This is a phenomenon that occurs in Therefore, the larger the electric field, ion density, neutral atom density, ion mass, and neutral atomic mass, the more likely it is to occur. In the case of high-pressure discharge lamps, both neutral atoms and ions are mainly composed of mercury.

Therefore, we prototyped a high-pressure discharge lamp in which the mercury vapor density changes during lighting operation while keeping the lamp voltage the same during lighting, performed frequency modulation high-frequency lighting, and investigated the region where acoustic resonance phenomena occur. did. The results are shown in FIG. As is clear from the figure, the higher the mercury vapor density, the wider the area where the acoustic resonance phenomenon occurs. Therefore,
When the mercury vapor density and the unstable area ratio during lighting operation are plotted using the same method as described above, the result is shown in FIG. 22. Here, as above, if the limit for avoiding the acoustic resonance phenomenon is set to 50% in terms of the ratio of the unstable region, the mercury vapor density during operation is 7.5 ng/ai! The following is sufficient. The shape of the arc tube used in the experiment was the same as that shown in FIG. 5 (bl) above, and the dimensions of each are as follows.

Pipe inner diameter D: 15 mm Curved surface dimension Lr2: 6IIIll Distance between electrodes Lp As shown in Figure 21 fa): 80 mm As shown in Figure 21 fbl: 60 mm As shown in Figure 21 (C1: 40 mm As shown in Figure 21 (di) Shown: 2011Il11 The mercury vapor density during lighting operation is shown in Figure 21 ta>, (bl, (
C1, (corresponding to di, 1.95■/d, 2
゜83ng/c+4.4.56mg/c+4.13.3
0 axr/ctl, and the percentages of unstable regions are 1%, 13%, 29%, and 100%, respectively.

Next, we prototyped a high-pressure discharge lamp in which the electric field strength of the arc column changes during lighting operation while keeping the lamp voltage the same, and conducted frequency-modulated high-frequency lighting to determine the region where acoustic resonance occurs. It was investigated. Note that the shape and dimensions of the arc tube used in the experiment are the same as those used in the study of the mercury vapor density during the lighting operation, and the results are also the same as those shown in FIG. 21, so a description thereof will be omitted. As is clear from Fig. 21, the arc column electric field strength is thick (indeed, the area where acoustic resonance phenomenon occurs is wide).Therefore, using the same method as described above, we calculated the arc column electric field strength during lighting operation and the unstable region. If the ratio is plotted, it will be as shown in Fig. 23.

Here, as above, if the limit for avoiding the acoustic resonance phenomenon is set to 50% in terms of the proportion of the unstable region, the arc column electric field strength during operation may be 40 V/cra or less.

The arc column electric field strength during lighting operation is shown in Figure 21 (al
, (bl, (C), (d), respectively, 13.
3V/cm, 18.8V/c+a, 25.3V
/ C11,67, OV/Cot.

However, the arc column electric field strength is (lamp voltage [V] - 20 [
V]), /interelectrode distance [cLII].

Furthermore, power consumption per unit volume within the arc column during lighting operation will be explained. We prototyped a high-pressure discharge lamp that changes the power consumption per unit volume in the arc column during lighting operation while keeping the shape of the end of the arc tube similar, and performed frequency-modulated high-frequency lighting. The region where acoustic resonance phenomena occur was investigated. The results are shown in FIG. As is clear from the figure, the larger the power consumption per unit volume within the arc column, the wider the area where the acoustic resonance phenomenon occurs. Therefore, when the power consumption per unit volume in the arc column during lighting operation and the ratio of the unstable region are plotted using the same method as described above, the result is shown in FIG. 25. Here, as above, if the limit for avoiding the acoustic resonance phenomenon is set to 50% in terms of the proportion of the unstable region, the power consumption per unit volume in the arc column during operation should be 350 W/cn+ or less. .

The shape of the arc tube used in the experiment is shown in Figure 5(b) above.
The dimensions are as follows: tube inner diameter: D, curved surface dimension: L r 2 , distance between electrodes: Lp (at: D=18+nm Lr2=6nv+L
p-75mmfb): D=15mm Lr2=6m
m Lp=55mm (Cl:D='14mm Lr
2=6mm Lp=24mm The power consumption per unit volume in the arc column during lighting operation is shown in Figure 24 (al, (
b), (corresponding to C1, respectively 109 W/cTA
, 180 W/cat, and 382 W/cnl, and the percentages of unstable regions are 2%, 13%, and 10, respectively.
It is 0%.

(Effects of the Invention) As described above, the present invention provides a high-pressure discharge lamp having an arc tube whose end shape has a curved surface that expands from the electrode-sealed end toward the center of the arc tube. Alternatively, the acoustic resonance phenomenon can be avoided by lighting a high-pressure discharge lamp with an arc tube formed such that the electrode sealed end is located off the center axis of the arc tube using a frequency modulation method. This makes it possible to provide a high-pressure discharge lamp that can prevent arc column curvature, fluctuation, extinguishing, and arc tube destruction, and can maintain stable lighting.

[Brief explanation of drawings]

Fig. 1 is a front view showing a conventional high-pressure discharge lamp, Fig. 2 is a circuit diagram showing an example of a frequency modulation lighting device used in the present invention, and Fig. 3 (al and bl show experimental results regarding the conventional example). Figures 4+8) to 4(0) are diagrams showing the experimental results of the present invention, respectively. Figures 5(al) and (b) are front views showing the shape and dimensions of the arc tube used in the above experiment, Figure 6 is a diagram showing the ratio of unstable area to curved surface dimension/tube inner diameter created based on the above experimental results, Figure 7 Ta) is a front view showing arc tubes of different shapes according to the present invention, Figure 7 (to))
8 is a cross-sectional view taken along the line A-A' of the same as above, FIG. 8 is a diagram showing the experimental results regarding the arc tube shown in FIG. 7, and FIG. Front view,
FIG. 10 is a diagram showing experimental results related to the present invention, FIG. 11 is a cross-sectional view of an arc tube related to a conventional small high-pressure discharge lamp, and FIG.
2 and 13 are sectional views of the arc tube of the compact high-pressure discharge lamp of the present invention, and FIGS. 14(a) and (bl
is a diagram showing the experimental results related to the second invention, FIG. 15 (81
~(C1 is a front view showing the shape and dimensions of the arc tube used in the above experiment, FIG. 16 fa) ~(fl is a diagram showing the shape of the arc tube used in the above experiment, FIGS. 17 and 18! 8+,
(b) is a diagram showing the experimental results according to different embodiments of the second invention, FIGS. 19 and 20 are respectively cross-sectional views of the arc tube according to the small high-pressure discharge lamp of the second invention, and FIG. Figures 22 and 23 are diagrams showing the experimental results of further different examples, Figures 22 and 23 are diagrams each showing the proportion of unstable regions created based on the above experimental results, and Figure 24 is the experimental results of further different examples. FIG. 25 is a diagram showing the proportion of unstable regions created based on the above experimental results.

Claims (6)

[Claims] (1) A high-pressure discharge lamp with an arc tube whose end shape has a curved surface that expands from the electrode-sealed end toward the center of the arc tube is lit at high frequencies using a frequency modulation method. Characteristic high pressure discharge lamp. (2) The value obtained by dividing the curved surface dimension of the arc tube by the tube inner diameter is 0.
The high-pressure discharge lamp according to claim 1, which is the above. (3) The high-pressure discharge lamp according to claim 1, comprising an arc tube whose mercury vapor density is maintained at 7.5 mg/cm^3 or less. (4) The high-pressure discharge lamp according to claim 1, comprising an arc tube whose arc column electric field strength is maintained at 40 V/cm or less. (5) Power consumption per unit volume of arc column is 350W/c
The high-pressure discharge lamp according to claim 1, comprising an arc tube maintained at m^3 or less. (6) A high-pressure discharge lamp having an arc tube whose end shape is such that the electrode-sealed end is located off the center axis of the arc tube is operated at high frequency using a frequency modulation method. Characteristic high pressure discharge lamp.