Discharge lamp

Abstract

To provide a lamp whose rise time is short.SOLUTION: A discharge lamp includes an arc tube in which mercury is sealed, a first electrode and a second electrode disposed facing each other with a space therebetween in a first direction inside the arc tube, an electrode bar connected to the first electrode on a side opposite to the second electrode and extending along the first direction, and a support part that supports the electrode bar. When the first direction is a direction that is substantially vertical to a horizontal plane and the first electrode is disposed below the second electrode, a length D1 (mm) of an outer periphery of the electrode bar, a height H1 (mm) of the mercury from the support part, and a volume V1 (mm3) of the mercury sealed in the arc tube satisfy Expression (1): D1×H1 / V1≥0.079 (mm-1)...(1).SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a discharge lamp in which mercury is sealed in an arc tube. [Background technology]

[0002] 2. Description of the Related Art Discharge lamps (hereinafter simply referred to as "lamps") that use mercury as a luminous material are used as light sources for exposure devices and the like used in the manufacturing process of flat panel displays and the like.

[0003] In the above lamp, when the pair of electrodes arranged in the arc tube are lit with the direction in which they face each other horizontally, the convection of mercury vapor in the arc tube tends to make the arc generated between the pair of electrodes uneven. For this reason, the lamp is typically lit with the direction in which the pair of electrodes face each other perpendicular to the horizontal plane (hereinafter simply referred to as "vertical lighting").

[0004] Because mercury has a low melting point, it is in a condensed liquid state below the arc tube before the lamp is lit. In other words, in a lamp that is positioned at a right angle to the horizontal for vertical lighting, the mercury is condensed in contact with the electrode rod connected to the lower electrode of a pair of electrodes.

[0005] The lamp's arc tube is filled with a noble gas (also called a rare gas) to assist in starting the lamp. In this state, when a high voltage is applied between the electrodes via the bases located at both ends of the lamp, dielectric breakdown occurs between the electrodes. By continuing to supply power, the lamp transitions to an arc discharge and lights up. After the lamp is turned on, the pair of electrodes becomes hot due to heating by the arc, and the liquid mercury is heated mainly via the electrode rods and evaporates. In the above lamp, the desired light is obtained stably as the enclosed mercury evaporates.

[0006] In recent years, for example, in exposure devices used in the manufacturing process of flat panel displays, lamps with longer life are required to reduce downtime due to lamp replacement and to cut running costs. Accordingly, the heat capacity of lamps is often increased, which lengthens the time required for mercury evaporation during lighting. In other words, the time from when power is turned on to when the desired light is obtained from the lamp (hereinafter, for convenience, referred to as the "start-up time") is becoming longer.

[0007] However, in an exposure apparatus, the lamp warm-up time means downtime, so there is a demand for a short warm-up time even for lamps that have a large heat capacity and thus a long life.

[0008] Therefore, in order to shorten the lamp warm-up time, the applicant has developed a lamp that can efficiently supply heat to the mercury when the lamp is lit. For example, in Patent Document 1, a heat conductive plate is disposed in contact with an electrode rod that comes into contact with the condensed mercury. Patent Document 1 proposes that the heat of the electrode rod, which becomes hot when lit, is efficiently transferred to the mercury via the heat conductive plate. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] JP 2001-15070 A Summary of the Invention [Problem to be solved by the invention]

[0010] However, the lamp described in Patent Document 1 is manufactured by passing an electrode rod through a heat conductive plate having a hole, so the inner diameter of the hole in the heat conductive plate needs to be larger than the outer diameter of the electrode rod. If a gap is generated between the electrode rod and the heat conductive plate, the heat from the electrode rod is not easily transferred to the heat conductive plate. For this reason, the lamp described in Patent Document 1 requires time to heat the mercury, and there is room for improvement in the lamp start-up time.

[0011] In view of the above circumstances, an object of the present invention is to provide a lamp having a short rise time. [Means for solving the problem]

[0012] The discharge lamp according to the present invention comprises: A light emitting tube containing mercury; a first electrode and a second electrode disposed opposite each other and spaced apart from each other in a first direction inside the arc tube; an electrode rod connected to the first electrode on a side opposite to the second electrode and extending along the first direction; A support portion for supporting the electrode rod, When the first direction is a direction substantially perpendicular to a horizontal plane and the first electrode is disposed below the second electrode, The outer circumferential length D1 (mm) of the electrode rod, the height H1 (mm) of the mercury from the support, and the volume V1 (mm) of the mercury enclosed in the arc tube 3 ) is characterized in that it satisfies the following formula (1). D1×H1 / V1 ≧ 0.079 (mm -1 ) …(1)

[0013] Here, "substantially right angle" means that the angle of the electrode rod with respect to the horizontal plane is within the range of 90°±0.5°.

[0014] The inventors have arrived at the above-mentioned discharge lamp configuration. When the lamp is started, the electrode rod is heated mainly by heat from the first electrode. Therefore, by increasing the area of ​​contact between the electrode rod and liquid mercury (hereinafter, for convenience, referred to as the "contact area"), the mercury can be efficiently heated when the lamp is started. In addition, since the lamp is lit stably when the mercury in the arc tube evaporates, it is necessary to consider the amount of enclosed mercury. In view of these points, the inventors thought that a lamp with a short start-up time could be realized by increasing the contact area between the electrode rod and mercury relative to the volume of mercury enclosed in the arc tube. The contact area corresponds to the product of the length D1 and the height H1.

[0015] The inventors of the present invention have devised the above configuration as a result of extensive research. With the above configuration, it is possible to efficiently heat mercury when starting the lamp, and to realize a lamp with a short warm-up time. This shortens the time required from starting the lamp to lighting it, and reduces downtime of the exposure device, etc. Details will be described later in the section "Mode for carrying out the invention."

[0016] When the lamp is turned on, the lamp voltage rises as the mercury evaporates, but a long lamp rise time means that the voltage rise is slow. For safety reasons, the lamp lighting power supply built into an exposure device or the like may be set to stop applying voltage if the lamp voltage does not reach a predetermined voltage within a certain time, determining that an abnormality has occurred in the lamp. In this case, if the lamp rise time is long, the lamp lighting power supply stops applying voltage. As a result, even if there is no problem with the characteristics of the lamp during stable lighting, the lamp may be forcibly turned off before stable lighting is achieved simply because of its long rise time.

[0017] In contrast, the lamp according to the present invention has a short lamp rise time, and therefore has the advantage that the problem of the lamp being forcibly turned off by the operation of the lighting power supply is unlikely to occur.

[0018] In the above discharge lamp, The length D1 (mm), the height H1 (mm) of the mercury, and the volume V1 (mm 3 ) may further satisfy the following formula (2): D1×H1 / V1 ≦ 0.2(mm -1 ) …(2)

[0019] The liquid mercury is condensed between the electrode rod and the inner wall surface of the arc tube. In the above lamp, if the distance L1 between the electrode rod and the arc tube in the direction perpendicular to the first direction is reduced, the height H1 of the mercury increases. In other words, reducing the distance L1 has the advantage of increasing the contact area between the electrode rod and the mercury, provided that the amount of mercury is not changed.

[0020] Methods for reducing the distance L1 include increasing the outer diameter of the electrode rod to lengthen the length D1, or reducing the inner diameter of the arc tube. However, if the distance L1 is reduced, there is a concern that the mechanical strength of the lamp will be reduced and the arc tube will be more likely to break. In view of this, it is preferable that D1, H1, and V1 satisfy the above formula (2).

[0021] In the above discharge lamp, The volume V1 of the mercury is 1480 (mm 3 ) or more.

[0022] In lamps with a large amount of enclosed mercury, the time required for the mercury to evaporate is long, and the lamp warm-up time is also long. In contrast, with the above-mentioned configuration, the mercury can be heated efficiently, so the enclosed amount of mercury can be 20 g or more. The volume of 20 g of mercury at room temperature of 25°C is approximately 1480 mm 3 It is.

[0023] In the above discharge lamp, The first electrode may be a cathode.

[0024] In the arc formed between the pair of electrodes, it is preferable to arrange the cathode below the anode in order to align the direction of the plasma airflow generated from the cathode with the direction of convection of mercury vapor caused by heat, thereby stabilizing the arc.

[0025] Here, the anode is more likely to reach a higher temperature than the cathode due to heating caused by the inflow of electrons. In other words, the cathode is less likely to rise in temperature than the anode. In other words, when the lamp is lit vertically, it takes longer to heat the mercury when the cathode is placed below the anode than when the anode is placed below the cathode, and the lamp rise time is longer. In contrast, with the above configuration, the mercury can be heated efficiently, so that a lamp with a short rise time can be realized while stabilizing the arc by placing the cathode below the anode. Effect of the Invention

[0026] In accordance with the present invention, a lamp is provided that has a fast rise time. [Brief description of the drawings]

[0027] [Figure 1] 1 is a cross-sectional view showing a schematic diagram of an embodiment of a discharge lamp according to the present invention. [Figure 2A] 2 is an enlarged view of the cathode side of the discharge lamp shown in FIG. 1. [Figure 2B] 2B is a cross-sectional view of FIG. 2A. [Diagram 3] This is a schematic diagram showing how the height of mercury is measured. [Figure 4] 11 is a graph showing the transition of lamp voltage during verification. [Diagram 5] 1 is a graph showing the relationship between the S1 / V1 ratio and the rise time. [Figure 6] FIG. 2B is a cross-sectional view showing a schematic diagram of a modified example of the lamp, following FIG. 2A. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] An embodiment of a discharge lamp according to the present invention will be described with reference to the drawings. Note that each drawing, except for the following graphs, is a schematic illustration, and the dimensional ratios in the drawings do not necessarily match the actual dimensional ratios. Furthermore, the dimensional ratios between the drawings do not necessarily match.

[0029] Fig. 1 is a cross-sectional view showing a schematic diagram of an embodiment of a discharge lamp according to the present invention. As shown in Fig. 1, the discharge lamp (hereinafter simply referred to as "lamp 1") includes an arc tube 2 filled with mercury 9 (not shown in Fig. 1; see Fig. 2A described later), a cathode 3 and an anode 4 arranged opposite each other, and sealing portions (5, 6).

[0030] In the following drawings, the direction in which the cathode 3 and the anode 4 face each other is defined as the Z direction, and the plane perpendicular to the Z direction is defined as the XY plane. The Z direction is typically perpendicular to the horizontal plane. The Z direction corresponds to the "first direction."

[0031] In the following description, when a positive or negative direction is to be distinguished from a positive or negative direction, the direction is described with a positive or negative sign, such as "+X direction" and "-X direction". When a direction is to be described without distinguishing between positive and negative directions, the direction is simply described as "X direction". In other words, in this specification, when the direction is simply described as "X direction", both the "+X direction" and the "-X direction" are included. The same applies to the Y direction and the Z direction.

[0032] The arc tube 2 has a light emitting portion 10 having, for example, a spherical or ellipsoidal shape. The arc tube 2 also has a first side tube 11 connected to an end portion on the -Z side of the light emitting portion 10, and a second side tube 12 connected to an end portion on the +Z side of the light emitting portion 10. The light emitting portion 10, first side tube 11, and second side tube 12 constituting the arc tube 2 are integrally formed from a glass material such as quartz glass.

[0033] Furthermore, the arc tube 2 has an exhaust pipe remnant 13 at a certain location. When the lamp 1 is manufactured, an exhaust pipe (not shown) that exhausts gas from the arc tube 2 and seals mercury 9 as a luminous material inside the arc tube 2 is formed at a certain location of the arc tube 2. The exhaust pipe remnant 13 is a trace left after the exhaust pipe is removed, and has a shape that protrudes from the arc tube 2.

[0034] The sealing portions (5, 6) seal both sides in the Z direction of the arc tube 2. More specifically, the sealing portion 5 seals the first side tube 11, and the sealing portion 6 seals the second side tube 12. By sealing both sides in the Z direction of the arc tube 2, a light-emitting space E1 is formed within the arc tube 2. Note that a noble gas such as argon or xenon is enclosed in the light-emitting space E1 for the purpose of assisting the starting of the lamp 1.

[0035] In the light-emitting space E1, a cathode 3 and an anode 4 are disposed facing each other. In this embodiment, the cathode 3 corresponds to the "first electrode" and the anode 4 corresponds to the "second electrode." The lamp 1 is a short arc type discharge lamp in which the cathode 3 and the anode 4 are disposed facing each other with a gap of 40 mm or less (a value at room temperature without thermal expansion).

[0036] A first electrode rod 7 is connected to the cathode 3, and a second electrode rod 8 is connected to the anode 4. The first electrode rod 7 and the second electrode rod 8 extend along the Z direction. As an example, the outer diameters of the first electrode rod 7 and the second electrode rod 8 are 1 mm to 12 mm. In this embodiment, the outer diameters of both the first electrode rod 7 and the second electrode rod 8 are 8 mm, but the outer diameters of the two may be different. In this embodiment, the first electrode rod 7 corresponds to the "electrode rod".

[0037] The cathode 3, the anode 4, the first electrode rod 7, and the second electrode rod 8 are made of a material containing, for example, tungsten. As an example, the cathode 3, the anode 4, the first electrode rod 7, and the second electrode rod 8 have a shape of a body of revolution about an axis A1 extending in the Z direction.

[0038] Fig. 2A is an enlarged view of the cathode 3 side of the lamp 1. Fig. 2B is a cross-sectional view taken along line BB in Fig. 2A. As shown in Fig. 2A, a supporting cylinder 14, a metal foil 16, a metal plate 26, a glass member 18, and a metal foil 22 are arranged within a first side tube 11 of the lamp 1. The supporting cylinder 14 and the metal foil 16 form a first supporting portion 7a that supports the first electrode rod 7. The first supporting portion 7a corresponds to a "supporting portion." The glass member 18 and the metal foil 22 form a sealing portion 5 that seals the first side tube 11.

[0039] As shown in Fig. 2A, the first electrode rod 7 is inserted into the supporting cylinder 14. The metal foil 16 is disposed between the supporting cylinder 14 and the first electrode rod 7 to prevent misalignment of the first electrode rod 7 and welding of the first electrode rod 7 to the supporting cylinder 14. The outer circumferential surface of the supporting cylinder 14 is welded to the inner circumferential surface of the first side tube 11. Fig. 2B shows a schematic diagram of a separation distance L1 between the first side tube 11 and the first electrode rod 7 in a direction perpendicular to the Z direction on the +Z side of the supporting cylinder 14.

[0040] The supporting cylinder 14 has a shape of a body of revolution about an axis A1. The supporting cylinder 14 is made of a glass material such as quartz glass. An example of the metal foil 16 is a molybdenum foil.

[0041] On the -Z side of the supporting cylinder 14, a glass member 18 is disposed, which seals the first side tube 11 with a metal plate 26 sandwiched therebetween. In addition, a metal foil 22 made of, for example, molybdenum is disposed around the glass member 18. For example, a plurality of metal foils 22 in the shape of strips are disposed spaced apart from each other in the circumferential direction of the glass member 18. The outer peripheral surface of the glass member 18 is fused to the inner peripheral surface of the first side tube 11 directly or via the metal foil 22. In this way, the sealing portion 5 seals the -Z side of the arc tube 2.

[0042] Furthermore, the glass member 18 has a hole recessed from the end on the -Z side toward the +Z side. An external lead rod 20 is inserted into the hole. Furthermore, a cylindrical body 21 made of, for example, quartz glass is disposed on the -Z side of the glass member 18 with a metal plate 27 sandwiched therebetween. The external lead rod 20 is inserted into the cylindrical body 21, and the outer circumferential surface of the cylindrical body 21 is fused to the inner circumferential surface of the first side tube 11.

[0043] The external lead rod 20 is connected to the first electrode rod 7 via the metal foil 22 and the metal plates (26, 27).

[0044] A base 23 that covers the periphery of the first side tube 11 is disposed at the end on the -Z side of the first side tube 11. The base 23 is connected to the outer lead rod 20.

[0045] The configuration of the +Z side of the arc tube 2 is similar to that of the -Z side, and will be described briefly. A supporting cylinder 15, a metal foil 17, a glass member 19, and a metal foil 24 are arranged inside the second side tube 12 of the lamp 1. As described for the first side tube 11, a metal plate (not shown) is arranged between the supporting cylinder 15 and the glass member 19. The second electrode rod 8 is inserted into the supporting cylinder 15, and the metal foil 17 is arranged between the supporting cylinder 15 and the second electrode rod 8. The supporting cylinder 15 and the metal foil 17 form a second support portion 8a that supports the second electrode rod 8. The outer peripheral surface of the glass member 19 is fused to the inner peripheral surface of the second side tube 12 via the metal foil 24 or directly. In this manner, the sealing portion 6 seals the +Z side of the arc tube 2.

[0046] Moreover, the configuration on the +Z side of the supporting cylinder 15 is similar to the configuration on the -Z side of the supporting cylinder 14. For this reason, the +Z side of the supporting cylinder 15 is simplified in Fig. 1. In the lamp 1, a voltage is applied between the cathode 3 and the anode 4 via a pair of bases 23.

[0047] Mercury 9 is enclosed as a luminous substance in the light emitting space E1 (see FIG. 2A). As an example, the amount of mercury 9 enclosed is 5 g to 100 g (volume at room temperature of 25° C.: about 740 mm 3 ~Approx. 7390mm 3 ) is said to be

[0048] Fig. 2A shows a schematic diagram of the lamp 1 at room temperature. Since the melting point of mercury 9 is low, at room temperature, the mercury 9 comes into contact with the first electrode rod 7 and the first support portion 7a inside the first side tube 11, condenses in a liquid state, and accumulates on the first support portion 7a. Fig. 2A also shows the height H1 of the mercury 9 from the first support portion 7a.

[0049] The contact area S1 between the first electrode 7 and the mercury 9 is calculated by multiplying the outer periphery of the first electrode 7 by the height H1, where D1 (mm) is the outer periphery of the first electrode 7. In the lamp 1, the volume V1 (mm 3 ) the ratio of the contact area S1 to the -1 The above is configured.

[0050] Next, the operation of the lamp 1 when it is turned on will be described.

[0051] When application of voltage to the lamp 1 begins, the cathode 3 and the anode 4 are heated by arc discharge between the electrodes. Then, the first electrode 7 is heated by thermal conduction from the high-temperature cathode 3. Furthermore, the mercury 9 that has been condensed in contact with the first electrode 7 is heated by thermal conduction from the first electrode 7.

[0052] The mercury 9 is heated and evaporated, causing the lamp voltage to increase. When the voltage reaches, for example, the rated voltage of the lamp 1, the desired light is obtained from the lamp 1.

[0053] [verification] A number of lamps were produced with different ratios of the contact area S1 to the volume V1 of the mercury 9 (hereinafter, for convenience, referred to as "S1 / V1 ratio"), and the rise time of each lamp was examined, which will be described below.

[0054] In this verification, the configuration of the lamp 1 according to the above embodiment was adopted, and the lamp was lit vertically with the cathode 3 below the anode 4.

[0055] As described above, the mercury 9 is condensed in the first side tube 11 while in contact with the first electrode rod 7. In other words, assuming that the amount of mercury is the same, when the distance L1 between the first side tube 11 and the first electrode rod 7 decreases, the height H1 of the mercury 9 increases and the contact area S1 between the first electrode rod 7 and the mercury 9 increases. In light of this, in this verification, lamps with different S1 / V1 ratios were produced by varying the distance L1 while keeping the amount of mercury 9 enclosed the same.

[0056] Furthermore, in lamp lighting power supplies, the voltage at which it is determined that the lamp has started up normally after lighting (hereafter, for convenience, referred to as the "reference voltage") is typically set in the range of 70% to 80% of the design center value of the lamp voltage during stable lighting. In light of this, in this verification, the lamp start-up time was defined as the time it takes for the voltage to reach 75% of the above-mentioned design center value.

[0057] Next, we will explain the method for measuring the S1 / V1 ratio of each lamp. The S1 / V1 ratio was measured after measuring the rise time of each lamp.

[0058] First, the remaining exhaust tube portion 13 of the lamp at room temperature was cut, and the arc tube 2 of the lamp was tilted to allow mercury 9 to flow out from the cut portion, and the amount (g) of enclosed mercury 9 was measured. 3 Dividing by this gives us the volume V1 of mercury 9.

[0059] Next, the arc tube 2 of the lamp was cut at a position between the cathode 3 and the anode 4, and the lamp was divided into the cathode 3 side and the anode 4 side. In this verification, the side on which mercury 9 was condensed was the cathode 3 side. Therefore, the part on the cathode 3 side was set as the target part for measurement. Since the cathode 3 interfered with the measurement of the height H1, the connection part between the cathode 3 and the first electrode rod 7 was cut, and the cathode 3 was removed from the target part.

[0060] Fig. 3 is a diagram showing a schematic diagram of measuring the height H1 of the mercury 9. As shown in Fig. 3, the target part 30 is fixed by an arbitrary support member 31 and placed on a surface plate 32 so that the first electrode rod 7 is at a substantially right angle to the horizontal plane. Note that "substantially right angle" here means that the angle of the first electrode rod 7 with respect to the horizontal plane is within the range of 90°±0.5°.

[0061] Thereafter, the probe 34 of the height gauge 33 was brought into contact with the supporting cylinder 14 of the target portion 30, and this state was set as the reference height of the height gauge 33. Next, the probe 34 of the height gauge 33 was raised, and the mercury 9 removed in the previous operation was poured into the target portion 30. The probe 34 of the height gauge 33 was then lowered, and the amount of displacement from the reference at the point when the probe 34 touched the mercury 9 was set as the height H1 of the mercury 9. The probe 34 was raised and lowered at a midpoint between the first electrode rod 7 and the inner wall surface of the first side tube 11 on the XY plane.

[0062] Any type of height gauge 33 can be used, but from the viewpoint of making it easier to measure the height H1, a rod-shaped member may be attached to the measuring element 34 of the height gauge 33.

[0063] The contact area S1 is calculated by multiplying the outer periphery D1 of the first electrode rod 7 by the height H1 of the mercury 9. The S1 / V1 ratio is calculated by dividing the contact area S1 by the volume V1 calculated in the previous measurement.

[0064] In this verification, the diameter of the first side tube 11 was made different in the region on the +Z side of the first support portion 7a, thereby making the separation distance L1 different for each lamp. Note that, although the outer diameter of the +Z side of the support cylinder 14 was appropriately adjusted by changing the diameter of the first side tube 11 in this region, the configuration of the -Z side of the first support portion 7a in each lamp is similar except for manufacturing errors. Also, just to be sure, since the wall surface of the first side tube 11 is curved, the separation distance L1 varies depending on the position in the Z direction. In this verification, "making the separation distance L1 different for each lamp" means that the average value of the separation distance L1 for each lamp was made different, taking into account the variation of the separation distance L1 due to the difference in the position in the Z direction. Below, the verification results will be described in order of the largest separation distance L1, as specifications 1 to 4.

[0065] In addition, as will be described in detail later, in order to take into account variations in lamp rise times, the rise times of a total of 10 lamps were measured under conditions similar to those of Specification 1 (hereinafter referred to as "equivalent to Specification 1").

[0066] [Verification results] The verification results obtained for each specification are shown in Table 1 below. As shown in Table 1, multiple lamps with different S1 / V1 ratios were produced in this verification.

[0067] [Table 1]

[0068] Fig. 4 is a graph showing the transition of the lamp voltage when each lamp is turned on. In Fig. 4, the horizontal axis shows the elapsed time from the point when the voltage application started as a reference, and the vertical axis shows the lamp voltage. In Fig. 4, the reference voltage Vb is shown by a dashed line.

[0069] As mentioned above, in this verification, the amount of enclosed mercury 9 was the same when each lamp was manufactured. In this regard, according to Table 1, it was confirmed that the amount of enclosed mercury 9 in each lamp was the same by the above-mentioned method of measuring the enclosed amount. In other words, it can be understood that the amount of enclosed mercury 9 can be measured by the above-mentioned method of measuring the enclosed amount even after the lamp has been lit.

[0070] It can be seen from Table 1 that the lamp rise time becomes shorter as the S1 / V1 ratio increases. This is consistent with the fact that the slope of the lamp voltage increase in Figure 4 increases as the S1 / V1 ratio increases. This is presumably because the contact area S1 increases relative to the volume V1 of the mercury 9. In other words, the larger the contact area S1, the more efficiently heat is transferred from the first electrode rod 7 to the mercury 9.

[0071] Figure 5 is a graph showing the S1 / V1 ratio on the horizontal axis and the lamp rise time on the vertical axis. Figure 5 shows an approximation line obtained by approximating the rise time of each lamp using the least squares method. Figure 5 clearly shows that the rise time becomes shorter as the S1 / V1 ratio increases, as described with reference to Table 1.

[0072] In addition, in this verification, from the viewpoint of considering the variation in the lamp rise time, a total of 10 lamps were manufactured under the same conditions as Specification 1, more specifically, under conditions with the same S1 / V1 ratio as Specification 1, and the variation in the rise time was confirmed. Incidentally, "same S1 / V1 ratio" means that the difference in the S1 / V1 ratio is within a range of ±5%. The results are shown in Table 2 below. If the lamp rise time follows a normal distribution and the population mean and population standard deviation are equal to the average value and standard deviation (σ) shown in Table 2, respectively, the range in which the rise time can be said to be shorter than that of a lamp equivalent to Specification 1 at a significance level of 5% is the range that is 1.64σ or more lower than the average rise time of the lamp equivalent to Specification 1. In other words, from Table 2, if the rise time is 9.97 minutes or less, it can be said that the rise time is better than that of Specification 1.

[0073] [Table 2]

[0074] In Figure 5, the reference rise time (9.97 minutes) obtained from Table 2 is shown by a dashed line. According to the approximation line in Figure 5, an S1 / V1 ratio of 0.079 is derived as the ratio for obtaining a lamp with a rise time better than 9.97 minutes. In other words, it can be understood that if the S1 / V1 ratio is set to 0.079 or more, a lamp with a rise time better than at least Specification 1 related to this verification can be obtained. This point is also consistent with the fact that excellent rise times were obtained with Specification 3 and Specification 4.

[0075] From the viewpoint of obtaining a lamp with a short rise time, the S1 / V1 ratio may be set to 0.09 or more.

[0076] In this verification, about 50 g of mercury 9 was enclosed, but this is merely an example. Considering the contact area between the mercury 9 and the first electrode rod 7, the amount of mercury 9 enclosed is preferably 20 g or more, and particularly preferably 40 g or more. In other words, the volume of the mercury 9 at room temperature is 1480 mm 3 More than 2960mm is preferable. 3 The above is particularly preferred.

[0077] In the above verification, the inner diameter of the area on the +Z side of the first support portion 7a of the first side tube 11 was changed, but it is also possible to increase the height H1 of the mercury 9 by changing the inner diameter and at the same time changing the outer diameter of the +Z side of the support cylinder 14, or by increasing the outer diameter of the first electrode rod 7.

[0078] In view of the results of this verification, it can be seen that the configuration described in the above embodiment makes it possible to realize a lamp with a short rise time.

[0079] [Variations] The following describes modifications of the lamp 1, focusing on the differences from the above embodiment.

[0080] <1> FIG. 6 is a cross-sectional view showing a schematic modification of the lamp 1. In FIG. 6, the -Z side of the lamp 1 is enlarged from the cathode 3 of the lamp 1, following FIG. 2A. As shown in FIG. 6, the lamp 1 may have a coil portion 25 in which a metal wire is wound around the first electrode rod 7. For example, by having the coil portion 25 made of a metal wire such as tantalum or niobium, it is possible to obtain an effect of absorbing impurity gases in the light-emitting space E1. In addition, in order to align the supporting cylinder 14, the coil portion 25 may be made of a tungsten wire and may be brought into contact with the supporting cylinder 14.

[0081] Since the metal wire constituting the coil portion 25 is wound around the first electrode 7, a small gap exists between the first electrode 7 and the coil portion 25. Mercury 9, which is in a liquid state at room temperature, enters the gap and is in contact with the first electrode 7. In other words, as shown in Fig. 6, even if the lamp 1 has the coil portion 25 around the first electrode 7, there is no need to take the coil portion 25 into consideration in the S1 / V1 ratio, and as in the above discussion, the lamp warm-up time can be shortened by setting the S1 / V1 ratio to 0.079 or more.

[0082] <2> In the above description, the lamp 1 is lit with the cathode 3 disposed below the anode 4. However, the lamp 1 may be lit with the anode 4 disposed below the cathode 3. In this case, the second electrode 8 corresponds to the "electrode", and in the discussion of the S1 / V1 ratio above, the first electrode 7 can be read as the second electrode 8.

[0083] <3> The configuration of the lamp 1 according to the present invention is not limited to the above-described embodiment. [Explanation of symbols]

[0084] 1: Discharge lamp 2: Arc tube 3 : Cathode 4: Anode 5,6: Sealing part 7 : First electrode rod 8 : Second electrode rod 7a: First support part 8a: Second support part 9 : Mercury 10: Light emitting part 11: First side pipe 12: Second side pipe 13: Remaining part of exhaust pipe 14,15: Support cylinder 16, 17, 22, 24: Metal foil 18,19: Glass materials 20: External lead rod 21 : Cylindrical body 23: Cap 25: Coil section 26,27 : Metal plate 30: Target area 31: Support member 32: Fixed plate 33: Height gauge 34: Probe

Claims

1. A light emitting tube containing mercury; a first electrode and a second electrode disposed opposite each other and spaced apart from each other in a first direction inside the arc tube; an electrode rod connected to the first electrode on a side opposite to the second electrode and extending along the first direction; A support portion for supporting the electrode rod, When the first direction is a direction substantially perpendicular to a horizontal plane and the first electrode is disposed below the second electrode, The outer circumferential length D1 (mm) of the electrode rod, the height H1 (mm) of the mercury from the support, and the volume V1 (mm) of the mercury enclosed in the light-emitting tube 3 ) is a discharge lamp characterized in that the following formula (1) is satisfied. D1×H1 / V1 ≧ 0.079 (mm -1 ) …(1)

2. In the above discharge lamp, The length D1 (mm), the height H1 (mm) of the mercury, and the volume V1 (mm 3 2. The discharge lamp according to claim 1, wherein: D1×H1 / V1 ≦ 0.2(mm -1 ) …(2)

3. The volume V1 of the mercury is 1480 (mm 3 3. The discharge lamp according to claim 1, wherein the number of light sources is equal to or larger than the number of light sources.

4. 3. The discharge lamp according to claim 1, wherein the first electrode is a cathode.

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