Short arc type mercury lamp

Abstract

The invention provides a short-arc mercury lamp with long service life. The short arc type mercury lamp is provided with a cathode, an anode, a light-emitting tube and a side tube, and satisfies the following formula (1) in a cross section passing through a rotational symmetry axis: [numerical formula 1] # imgabs0 # (in formula (1), A1 (mm) represents the length in the one axial direction from the closest position of the light-emitting tube closest to the anode to the anode-side end of the light-emitting tube, A1 (mm) represents the length in the one axial direction from the closest position of the light-emitting tube closest to the anode, and A2 (mm) represents the length in the one axial direction from the closest position of the light-emitting tube to the anode-side end of the light-emitting tube. B1 (mm) represents the inner diameter of the light-emitting tube at the closest position, C1 (mm) represents the length in the rotational symmetry axis direction from the anode-side end portion to the cathode-side end portion of the light-emitting tube, and D1 (mm) represents the inner diameter of the light-emitting tube at the most bulged position of the light-emitting tube.

Description

Technical Field

[0001] The present invention relates to a short arc mercury lamp. Background Art

[0002] As a light source used in an exposure device for manufacturing semiconductors, display devices, or wiring boards, a short arc type mercury lamp has been known. In a short arc type mercury lamp, an anode and a cathode for discharge are arranged opposite to each other in a light emitting tube that emits light by discharge, and mercury is sealed as a light emitting gas. The anode and the cathode are supported by lead rods, respectively, and each lead rod is supported by a pair of side tubes connected to both ends of the light emitting tube. Patent document 1 shows an example of such a short arc type mercury lamp.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2007-128755 Summary of the invention

[0006] Problems to be solved by the invention

[0007] When the short arc type mercury lamp is lit and an arc discharge is generated between the electrodes, a part of the material constituting the electrode is separated from the electrode. In addition, the material separated from the electrode sometimes diffuses along with the flow of the gas sealed in the light emitting tube 1 such as the light emitting gas (hereinafter, the gas sealed in the light emitting tube 1 is simply referred to as "gas") and adheres to the inner surface of the glass tube constituting the light emitting tube 1 to gradually form a blackened area. If the blackened area is formed on the inner surface of the glass tube, the transmittance of the glass tube decreases, and the illumination of the light radiated from the lamp decreases. This means that the service life of the lamp is deteriorated.

[0008] On the other hand, the market demands a longer life of a short arc type mercury lamp. In order to meet the market demand, an object of the present invention is to provide a short arc type mercury lamp with a longer life.

[0009] Technical solutions to solve problems

[0010] As will be described in detail later, the inventors studied the flow of gas for forming the blackened area as far as possible outside the effective utilization angle of light, focusing on the fact that the illumination does not decrease and the service life does not deteriorate when the blackened area is formed outside the effective utilization angle of light. Furthermore, the inventors conducted in-depth research and found the characteristics of the lamp for realizing the above-mentioned gas flow.

[0011] The short arc mercury lamp of the present invention has:

[0012] cathode;

[0013] an anode, arranged opposite to the cathode on one axis and having a larger volume than the cathode;

[0014] A light-emitting tube having the cathode and the anode inside and sealed with mercury, and having a rotationally symmetrical shape centered on the one axis;

[0015] A first side tube formed at an anode side end portion close to the anode among the ends on both sides of the light emitting tube; and

[0016] A second side tube is formed at a cathode side end portion close to the cathode among the ends of both sides of the light emitting tube,

[0017] In the cross section passing through the one axis, the following formula (1) is satisfied:

[0018] [Formula 1]

[0019]

[0020] In formula (1), A1 (mm) represents the length in the one axial direction from the closest position of the light-emitting tube to the anode side end of the light-emitting tube, B1 (mm) represents the inner diameter of the light-emitting tube at the closest position, C1 (mm) represents the length in the one axial direction from the anode side end of the light-emitting tube to the cathode side end, and D1 (mm) represents the inner diameter of the light-emitting tube at the most bulging position of the light-emitting tube.

[0021] As will be described in detail later, the short arc type mercury lamp ensures the volume of the upper space in the light emitting tube, so the flow of gas above the anode is less likely to become turbulent. When turbulence occurs above the anode, the flow of gas is directed to the effective utilization angle of light of the light emitting tube. By suppressing the turbulence above the anode, the flow of gas can be directed to the outside of the effective utilization angle of light of the light emitting tube.

[0022] Furthermore, the following formula (2) can also be satisfied:

[0023] [Formula 2]

[0024]

[0025] In formula (2), A1 (mm) represents the length in the one axial direction from the closest position of the light-emitting tube to the anode side end of the light-emitting tube, B1 (mm) represents the inner diameter of the light-emitting tube at the closest position, C1 (mm) represents the length in the one axial direction from the anode side end of the light-emitting tube to the cathode side end, D1 (mm) represents the inner diameter of the light-emitting tube at the most bulging position of the light-emitting tube, L1 (mm) represents the length in the one axial direction of the anode, and F2 (mm) represents the maximum diameter of the anode.

[0026] Effects of the Invention

[0027] This makes it possible to provide a long-life short-arc mercury lamp. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a diagram showing one embodiment of a short arc mercury lamp.

[0029] Figure 2A is Figure 1 The main part is enlarged in the figure showing the flow of gas.

[0030] Figure 2B is Figure 1 The main part is enlarged in the figure showing the flow of gas.

[0031] Figure 3 It is a stereoscopic diagram near the anode and cathode.

[0032] Figure 4A It is a diagram showing only the anode.

[0033] Figure 4B This is a diagram mainly showing a light-emitting tube and an anode.

[0034] Figure 5A It is a graph showing the relationship between the approximate value P1 of the volume ratio and the elevation angle θ1.

[0035] Figure 5B It is a graph which shows the relationship between the parameter P2 and the elevation angle θ1. DETAILED DESCRIPTION

[0036] The above-mentioned short arc type mercury lamp is described with reference to the accompanying drawings. In addition, the drawings disclosed in this specification are only drawings for schematic illustration. That is, the dimension ratios on the drawings are not necessarily consistent with the actual dimension ratios, and the dimension ratios between the drawings are not necessarily consistent.

[0037] The following description will be made with appropriate reference to the XYZ coordinate system. In addition, in this specification, when expressing a direction, when distinguishing between positive and negative directions, it is recorded by marking positive and negative signs, such as "+X direction" and "-X direction". In addition, when expressing a direction without distinguishing between positive and negative directions, it is only recorded as "X direction". That is, in this specification, when it is only recorded as "X direction", both "+X direction" and "-X direction" are included. The same is true for the Y direction and the Z direction. The -Z direction indicates the vertical direction downward (the direction of gravity).

[0038] [Overall structure of the lamp]

[0039] Figure 1An embodiment of a short arc type mercury lamp is shown. A short arc type mercury lamp 100 (hereinafter referred to as "lamp 100") of this embodiment includes: a light emitting tube 1; an anode 3 and a cathode 4, which are arranged opposite to each other in the Z direction in the interior of the light emitting tube 1; a first side tube 2a connected to one end of the light emitting tube 1 in the tube axis direction (Z direction); a second side tube 2b connected to the other end of the light emitting tube 1 in the tube axis direction; a first lead rod 5a connected to the anode 3; and a second lead rod 5b connected to the cathode 4. Mercury is sealed inside the light emitting tube 1. When a voltage is applied between the cathode 4 and the anode 3, arc discharge is generated in the mercury vapor and the lamp 100 emits light. In this specification, a "short arc type" lamp refers to a discharge lamp in which the anode 3 and the cathode 4 are arranged opposite to each other with a gap of 35 mm or less (value at room temperature without thermal expansion). In addition, a short arc type discharge lamp in which the anode 3 and the cathode 4 are arranged opposite to each other with a gap of 20 mm or less may be used. The details of the anode 3 and the cathode 4 will be described later.

[0040] When the lamp 100 is used, the lamp 100 is supported longitudinally so that the tube axis direction of the arc tube 1 is along the Z direction. The reasons for this are as follows: (1) the gas in the arc tube 1 can easily convect evenly around the tube axis direction, and the luminous efficiency is excellent; and (2) the lead bar (especially the first lead bar 5a) can easily withstand the weight of the electrode (especially the anode 3), and the lead bar is unlikely to bend or break. In addition, the lamp 100 can be arranged so that the anode 3 is located above the cathode 4 (on the +Z direction side). When the lamp 100 is lit, when the gas in the arc tube 1 is heated, convection occurs at the upper part of the arc tube 1, so the upper part of the arc tube 1 is higher in temperature than the lower part of the arc tube 1. The anode 3 is larger than the cathode 4, so the anode 3 has higher heat resistance than the cathode 4. Therefore, when the lamp 100 is arranged so that the anode 3 is located above the cathode 4, the heat resistance of the entire lamp 100 can be improved. The anode 3 and the cathode 4 are made of a material containing a high melting point metal, such as tungsten.

[0041] The arc tube 1 sandwiched between the first side tube 2a and the second side tube 2b is a region whose inner diameter increases from the end in the -Z direction or the +Z direction toward the center of the arc tube 1. The arc tube 1 is an arc tube having a rotationally symmetrical shape centered on the front Z1 axis. For example, it may be a sphere centered on a point on the Z1 axis, or an ellipsoid centered on the Z1 axis. In this specification, whether or not a shape such as a rotationally symmetrical shape, a sphere, or an ellipsoid is strictly determined based on the measurement results of the shape dimensions, but is determined based on the approximate overall shape. Specifically, even if the shape deviates from the size of the rotationally symmetrical shape, a sphere, or an ellipsoid due to manufacturing errors or local deformation, or there is a protrusion called an exhaust pipe in the arc tube 1, as long as the overall shape of the arc tube 1 is a roughly rotationally symmetrical shape, a sphere, or an ellipsoid, it is determined to be a rotationally symmetrical shape, a sphere, or an ellipsoid.

[0042] The first side tube 2a and the second side tube 2b may be centered on the Z1 axis respectively. The first side tube 2a is connected to one end of the light-emitting tube 1, and the second side tube 2b is connected to the other end of the light-emitting tube 1. The interiors of the first side tube 2a, the light-emitting tube 1, and the second side tube 2b are connected. The interiors of the first side tube 2a and the second side tube 2b are sealed relative to the outside of the lamp 100. The light-emitting tube 1, the first side tube 2a, the second side tube 2b, the anode 3, and the cathode 4 may be in a rotationally symmetrical shape centered on the common Z1 axis. Whether these components are in a rotationally symmetrical shape is not strictly determined based on the measurement results of the shape and size, but is determined based on the approximate overall shape. Specifically, even if the rotationally symmetrical shape is deviated due to manufacturing errors or local deformation, if the above-mentioned components are in a roughly rotationally symmetrical shape, they are also determined to be in a rotationally symmetrical shape. However, the light-emitting tube 1, the first side tube 2a, the second side tube 2b, the anode 3, and the cathode 4 may not be in a rotating body shape. In addition, the central axis of the light-emitting tube 1, the central axis of the first side tube 2a, and the central axis of the second side tube 2b all overlap with the Z1 axis, but the central axis of the light-emitting tube 1, the central axis of the first side tube 2a, and the central axis of the second side tube 2b do not necessarily overlap with the common axis. Figure 1 In FIG. 1 , point RP is a reference point of the light-emitting tube 1. The reference point RP is located on the Z1 axis and is located at a position equidistant from the front end of the anode 3 and the front end of the cathode 4.

[0043] The first lead rod 5a is connected to the anode 3 and extends in the first side tube 2a along the Z direction. The second lead rod 5b is connected to the cathode 4 and extends in the second side tube 2b along the Z direction. The central axis of each of the first lead rod 5a and the second lead rod 5b may overlap with the Z1 axis. The first lead rod 5a and the second lead rod 5b are made of a material containing a high melting point metal, such as tungsten.

[0044] The joint 12a covers the first side tube 2a on the side farther from the reference point RP (on the -Z direction side). The joint 12b covers the second side tube 2b on the side farther from the reference point RP (on the +Z direction side). The joint 12a is electrically connected to the first lead bar 5a, and the joint 12b is electrically connected to the second lead bar 5b. The lamp 100 is lit by supplying power from an external power source (not shown) through the joints (12a, 12b).

[0045] [Effective use of corners and blackened areas]

[0046] Figure 2A yes Figure 1 An enlarged view of the main part. Figure 2B It means Figure 2A Reference figure for the same parts.

[0047] Reference Figure 2A and Figure 2B , the effective light utilization angle and the desired blackening area are explained. Figure 2A , it is shown that a part of the surface of the light emitting tube 1 is in the A1 area. The A1 area represents the effective utilization angle of light. The effective utilization angle A1 refers to the range in which the light emitted from the arc AR can be effectively extracted from the light emitting tube 1. On the surface of the light emitting tube 1, in the area outside the effective utilization angle A1, the light emitted from the arc AR is blocked by the electrodes (3, 4), so the light emitted from the arc AR cannot be effectively extracted.

[0048] exist Figure 2A In FIG. 1 , a blackened area Ba1 is shown on the inner surface of the light-emitting tube 1. The blackened area refers to an area formed by the material separated from the electrodes (3, 4) diffusing with the flow of gas and adhering to the inner surface of the glass tube constituting the light-emitting tube 1, or an area of ​​the glass tube to which the material separated from the electrodes (3, 4) adheres. The light-emitting tube 1 is usually colorless and transparent. On the other hand, if the material separated from the electrodes (3, 4) adheres, the light-emitting tube 1 changes color to a light dark color and becomes opaque, and is therefore called a blackened area. In addition, in Figure 2A In the figure, only the material (the area shaded by diagonal lines) that has separated from the electrodes (3, 4) and adhered to and accumulated on the inner surface of the light emitting tube 1 is shown as the blackened area Ba1. As the blackened area Ba is used for a longer time, the area becomes larger or the light transmittance decreases. This is one reason for reducing the service life of the lamp 100.

[0049] [Fluid simulation]

[0050] The inventors found in the process of studying the long life of the lamp 100 that it is sufficient to maintain the transmittance within the effective use angle A1, and it is not necessary to maintain the transmittance outside the effective use angle A1. In addition, the inventors conducted a fluid simulation and repeatedly studied a method of forming a blackened area outside the effective use angle A1 without suppressing the formation of the blackened area. The details are described below.

[0051] Figure 2A The figure shows an example of the flow of gas obtained by the fluid simulation of the lamp 100. The dotted arrows f1 and f2a in the figure show the flow of gas in the arc tube 1. When the temperature of the luminous gas near the arc rises, a flow f1 of gas rising from the arc vicinity along the anode 3 is formed. After the flow f1, a flow f2a rising along the anode 3 is formed. The gas flows f1 and f2a contain substances separated from the electrodes (3, 4), especially from the anode 3. Therefore, when the flow f2a collides with the arc tube 1 or the first side tube 2a, the substances separated from the electrodes (3, 4) adhere to the collision area of ​​the arc tube 1 or the first side tube 2a to form a blackened area Ba1. As shown in the figure, the blackened area Ba1 is mainly outside the effective angle A1, so even if the blackened area Ba1 is formed, the influence on the intensity of the light taken out from the lamp 100 is small.

[0052] Figure 2B The flow of gas obtained by fluid simulation of a lamp different from the lamp 100 is shown. Figure 2B The gas flow f1 shown is Figure 2A The flow f1 of the gas shown is substantially the same. However, Figure 2B The gas flow f2b following the gas flow f1 and Figure 2A The flow f2b rises from the vicinity of the arc along the anode 3, and moves toward the radially outer side of the light-emitting tube 1, and collides with the light-emitting tube 1. When the flow f2b collides with the light-emitting tube 1, the material separated from the electrodes (3, 4) adheres to the collision area of ​​the light-emitting tube 1. Moreover, the blackened area B2 where the material separated from the electrodes (3, 4) adheres to the collision area of ​​the light-emitting tube 1 is within the effective use angle A1. Therefore, if the blackened area Ba2 is formed, the intensity of the light taken out from the lamp 100 is greatly affected.

[0053] [Gas flow evaluation method]

[0054] so, Figure 2A and Figure 2B The difference in the traveling direction of the gas flow f2 (f2a, f2b) following the gas flow f1 determines whether the blackened area is outside the effective angle A1. Therefore, a method of evaluating the traveling direction of the gas flow f2 will be described.

[0055] Figure 3 It is a perspective view of the vicinity of the anode 3 and the cathode 4. Figure 3 The points (m1 to m4) in are monitoring points. The monitoring points are points for finding out the direction of the gas flow f2 that affects whether the blackened area is outside the effective utilization angle A1. In other words, the direction of the gas flow f2 at the monitoring point affects whether the blackened area is outside the effective utilization angle A1.

[0056] The monitoring points (m1 to m4) can be represented by an XYZ coordinate system with the reference point RP as the origin (X, Y, Z) = (0, 0, 0). In this embodiment, it is clarified that in the process of continuing the fluid simulation, the monitoring points (m1 to m4) can be set as follows:

[0057] Monitoring point m1 (X, Y, Z) = (+30mm, 0mm, +10mm);

[0058] Monitoring point m2 (X, Y, Z) = (0 mm, +30 mm, +10 mm);

[0059] Monitoring point m3 (X, Y, Z) = (-30 mm, 0 mm, +10 mm);

[0060] Monitoring point m4 (X, Y, Z) = (0 mm, -30 mm, +10 mm).

[0061] In addition, when the anode front end surface is used as a reference, the above-mentioned monitoring points (m1 to m4) are all located at a position 14.3 mm away from the anode front end surface in the +Z direction.

[0062] like Figure 3 As shown, the angle θ1 formed between the traveling direction of the gas flow f2 at the monitoring point m1 and the XY plane is the elevation component of the gas flow f2. The size of the elevation angle θ1 affects the position of the blackened area. The same is true for the monitoring points m2 to m4. The size of the elevation angle θ at each monitoring point m2 to m4 has a greater impact on the position of the blackened area. In addition, the results of fluid simulation show that if the elevation angle θ1 is 50 degrees (deg.) or more, it is easy to obtain a blackened area outside the effective utilization angle A1.

[0063] [Light parameters and elevation angle]

[0064] In addition, the flow of the gas that affects whether the blackened area is outside the effective utilization angle A1 varies according to the parameters of the lamp 100, such as the size of the anode 3, the size of the arc tube 1, and the positional relationship of the anode 3 relative to the arc tube 1. Therefore, the relationship between the elevation angle θ1 of the flow f2 that affects the flow of the gas that determines whether the blackened area is outside the effective utilization angle A1 and the parameters of the lamp 100 is obtained by fluid simulation.

[0065] Table 1 shows the results of obtaining, by simulation, the average of the elevation angle θ1 of the gas flow f2 in 12 lamps (numbers S1 to S12) having different parameters of the lamp 100 .

[0066] [Table 1]

[0067]

[0068] Reference Figure 3 , Figure 4A as well as Figure 4B , describing the parameters of lamp 100 in Table 1. Figure 4A This is a diagram showing only the anode 3. Figure 4B This is a diagram mainly showing the arc tube 1 and the anode 3. It should be noted that, unless otherwise specified, the various dimensions shown below are the maximum values ​​among a plurality of measured values ​​obtained by repeatedly measuring the dimensions of the component while rotating the component (anode 3, arc tube 1 or cathode 4) around its central axis (e.g., Z1 axis) for one revolution.

[0069] Anode diameter F2 (mm): represents the diameter of the anode 3 centered on the Z1 axis (see Figure 4A ).

[0070] Anode total length L2 (mm): length of the anode 3 in the Z direction (see Figure 4A ).

[0071] The average elevation angle θ1 (deg.): is the arithmetic average of the elevation angles θ1 (deg.) at the four monitoring points (m1 to m4) (refer to Figure 3 , Figure 4A ).

[0072] Anode main body length L1 (mm): the length of the main body of the anode 3 (the portion with a constant diameter in the Z direction) in the Z direction (see Figure 4A ).

[0073] Minimum interval J1 (mm): indicates the shortest distance from the closest position J2 of the light emitting tube 1 to the anode 3 (refer to Figure 4B ). More specifically, the minimum value of the measured value when the distance between the arc tube 1 and the anode 3 is measured while the lamp 100 is rotated one circle around the Z1 axis is set as the minimum distance J1. The closest position J2 is the position when the minimum value is measured (hereinafter, the definition of the closest position J2 point is the same).

[0074] Upper space length A1 (mm): the length in the Z-axis direction from the closest position J2 of the arc tube 1 to the anode side end of the inner surface of the arc tube 1 (see Figure 4B ).

[0075] The inner diameter of the light-emitting tube B1 (mm): the inner diameter of the light-emitting tube 1 at the closest position J2 to the anode 3 (refer to Figure 4B ).

[0076] The total length C1 of the arc tube (mm): the length in the Z-axis direction from the anode side end of the inner surface of the arc tube 1 to the cathode side end of the inner surface of the arc tube 1 (see Figure 4B ).

[0077] Maximum inner diameter D1 (mm) of the arc tube: the inner diameter of the arc tube 1 at the most bulging position of the arc tube 1 (see Figure 4B ).

[0078] In this specification, there are expressions such as "the end portion on the anode side of the inner surface of the arc tube 1" and "the end portion on the cathode side of the inner surface of the arc tube 1". In practice, both the "end portion on the anode side of the inner surface of the arc tube 1" and "the end portion on the cathode side of the inner surface of the arc tube 1" may be in an R shape, and the positions of the ends may not be clearly determined. In such a case, the boundary between the imaginary surface extending toward the first side tube 2a while maintaining the curvature of the inner surface of the arc tube 1 and the imaginary surface extending toward the arc tube 1 from the inner surface of the first side tube 2a is defined as the "end portion on the anode side of the inner surface of the arc tube 1", and the boundary between the imaginary surface extending toward the second side tube 2b while maintaining the curvature of the inner surface of the arc tube 1 and the imaginary surface extending toward the arc tube 1 from the inner surface of the second side tube 2b is defined as the "end portion on the cathode side of the inner surface of the arc tube 1".

[0079] In addition, when obtaining Table 1, the following values ​​are commonly set for the following parameters.

[0080] The cone angle of the anode θ2 (refer to Figure 4A It should be noted that in the figure, the vertical angle having the same value as the cone angle of the anode 3 is marked with the symbol θ2): 100 (deg.);

[0081] The front diameter of the anode is F3 (refer to Figure 4A ): 8.0(mm);

[0082] Front end cone angle of cathode: 60 to 90 (deg.) It should be noted that the front end cone portion of the cathode 4 is not fixed to a constant value, so the front end cone angle is shown as a range;

[0083] The front end diameter of the cathode: 4.5 (mm).

[0084] According to Table 1, it is not possible to find the correlation between the individual values ​​of the various parameters of the anode 3 or the arc tube 1 and the elevation angle θ1 of the gas flow f2. However, the inventors found that the movement of the gas flow f2 and the upper space U1 of the arc tube 1 (see Figure 2B That is, when the flow of gas in the upper space U1 of the arc tube 1 becomes turbulent, Figure 2B In this way, the gas flow f2b moves toward the radially outer side of the arc tube 1 (the elevation angle θ1 becomes smaller). When the gas flow in the upper space U1 of the arc tube 1 is not turbulent, Figure 2A Thus, the gas flow f2a rises along the anode 3 (the elevation angle θ1 increases). The inventors have found that when the volume of the upper space U1 of the arc tube 1 is larger than the volume of the entire space of the arc tube 1, the gas flow in the upper space U1 becomes turbulent.

[0085] Therefore, the correlation between the ratio of the volume of the upper space U1 of the arc tube 1 to the volume of the entire space of the arc tube 1 and the elevation angle θ1 is studied. However, since a complicated calculation is required to obtain the volume, it takes time to obtain the ratio of the volume of the upper space U1 of the arc tube 1 to the volume of the entire space of the arc tube 1. Therefore, as an approximate value of the volume of the upper space U1 of the arc tube 1, the product of the upper space length A1 and the arc tube inner diameter B1 is used, and as an approximate value of the volume of the entire space of the arc tube 1, the product of the total length C1 of the arc tube and the maximum inner diameter D1 of the arc tube is used.

[0086] Furthermore, an approximate value P1 that approximates the ratio of the volume of the upper space U1 of the arc tube 1 to the volume of the entire space of the arc tube 1 is obtained by the following formula (3).

[0087] [Formula 3]

[0088]

[0089] It should be noted that A1, B1, C1, and D1 are values ​​measured in a cross section including the minimum distance J1 and the closest position J2 measured by rotating the arc tube 1 and the anode 3 once around the Z1 axis.

[0090] Table 2 shows the relationship between the elevation angle θ1 obtained by fluid simulation and the approximate value P1 (=[(A1·B1) / (C1·D1)]·100) of the ratio of the volumes.

[0091] [Table 2]

[0092]

[0093] Figure 5A This is a graph in which Table 2 is set as a scatter diagram, in which the approximate value P1 of the volume ratio (=[(A1·B1) / (C1·D1)]·100) is the horizontal axis and the elevation angle θ1 is the vertical axis. Straight line T1 is an approximate straight line of the curve obtained by the least squares method. It can be seen that the value of the approximate value P1 is correlated with the elevation angle θ1. As described above, if the elevation angle θ1 is 50 degrees (deg.) or more, it is easy to obtain a blackened area outside the effective utilization angle A1, so the approximate value P1 is preferably 20 or less.

[0094] [experiment]

[0095] The following experiment confirmed whether the above fluid simulation results were appropriate.

[0096] First, a lamp having the size of numbers S1 to S12 (see Table 1) used in the fluid simulation is manufactured one by one, and a total of 12 lamps with sample numbers S1 to S12 are obtained. The sample numbers S1 to S12 of the lamps correspond to the numbers S1 to S12 used in the fluid simulation in Table 1. Next, the 12 lamps are actually lit for a specified time, and the subsequent 12 lamps are analyzed. Table 3 shows the analysis results of the 12 lamps. In addition, whether the manufactured lamp 100 meets the parameters such as the minimum interval J1, the upper space length A1, the inner diameter B1 of the light-emitting tube, the total length C1 of the light-emitting tube, and the maximum inner diameter D1 of the light-emitting tube recorded in Table 1 is obtained by projecting light (visible light, X-rays depending on the situation) onto the lamp 100 and measuring the size of its projected image. In Table 3, the average of the elevation angle θ1 obtained by fluid simulation is recorded.

[0097] [Table 3]

[0098]

[0099] The evaluation method of the "degree of blackening" in Table 3 is described below. The degree of blackening of the light emitting tube 1 can be evaluated by finding the illuminance maintenance rate of the lamp. The illuminance maintenance rate is the percentage of the illuminance of the lamp after use when the lamp is lit for any time with respect to the illuminance of light of a specified wavelength, with reference to the initial illuminance immediately after the lamp is lit after manufacture. In this experiment, for sample numbers S1 to S12, the initial illuminance immediately after the lamp is lit after manufacture and the illuminance after use after 2000 hours of lighting at rated power were measured using a photodetector having a sensitivity to a wavelength of 365 nm. Then, the measured illuminance after use was divided by the measured initial illuminance and multiplied by 100 to obtain the illuminance maintenance rate (%). The case where the illuminance maintenance rate is 90% or more is evaluated as AA, the case where it is 85% or more and less than 90% is evaluated as A, and the case where it is less than 85% is evaluated as B. Here, regarding the evaluation values, AA, A, and B are used to indicate good results. Specifically, it can be considered that when the illumination maintenance rate is evaluated as AA, the degree of blackening is very small and excellent, when the illumination maintenance rate is evaluated as A, the degree of blackening is small and it is a qualified product (not reaching the life of the lamp), and when the illumination maintenance rate is evaluated as B, the degree of blackening is large and poor (reaching the life of the lamp). As can be seen from Table 3, when the elevation angle θ1 is 50.0 degrees or more, the evaluation of AA or A is obtained. It is confirmed that this result is consistent with the fluid simulation result. In addition, it can be seen that when the elevation angle θ1 is 53.0 degrees or more, the evaluation of AA is obtained.

[0100] Regarding the evaluation method of "presence of strain" in Table 3, the significance of evaluating "strain" is first described. In the lamps of sample numbers S1 to S12, the amount of heat received by the material constituting the arc tube 1 (e.g., quartz glass) varies due to the differences in various lamp parameters. When the amount of heat exceeds the heat resistance of the material constituting the arc tube 1, strain will occur in the material, shortening the life of the lamp. Therefore, the "presence of strain" was evaluated for the lamps that were lit at rated power for 2,000 hours.

[0101] The evaluation method of "presence or absence of strain" is explained. Generally, it is known that when strain occurs in the material constituting the light-emitting tube 1 (for example, quartz glass), the material exhibits a birefringent property. Therefore, the amount of strain is measured using the crossed Nicol method, which is one of the photoelasticity test methods that utilizes this property. That is, when a sample is inserted between a polarizer and an analyzer that are arranged in an orthogonal manner and monochromatic light is transmitted, the portion with strain appears bright and white, and the portion without strain appears dark and black. When the analyzer is rotated until the transmitted light of the portion with strain becomes dark, the rotation angle is expressed as the magnitude of the strain.

[0102] In this experiment, the analyzer was rotated until the transmitted light of the portion with strain became dark. As a result, the case where the rotation angle was less than 20 degrees was evaluated as AA, the case where the rotation angle was greater than 20 degrees and less than 45 degrees was evaluated as A, and the case where the rotation angle was greater than 45 degrees was evaluated as B. Here, regarding the evaluation values, good results are indicated in the order of AA, A, and B. Specifically, it can be considered that when the presence of strain is evaluated as AA, the lamp is not affected by the strain of the arc tube 1 and is extremely excellent, when the presence of strain is evaluated as A, the influence of the strain of the arc tube 1 is small and the lamp is a qualified product, and when the presence of strain is evaluated as B, the influence of the strain of the arc tube 1 is large and the lamp is defective (the lamp life has been reached). According to this standard, for sample number S1, it is judged that the lamp life has been reached based on the point of the strain amount, and for sample numbers S2 to S12, it is judged that the lamp life has not been reached based on the point of the strain amount, and in particular, for sample numbers S3 to S12, it is judged that the lamp is not affected by the strain.

[0103] Based on the above, it can be seen that the elevation angle θ1 is preferably 50.0 degrees or more and 62.0 degrees or less, and the elevation angle θ1 is more preferably 53.0 degrees or more and 61.7 degrees or less. In the case of the approximate value P1 (= [(A1·B1) / (C1·D1)]·100), P1 is preferably 1.0% or more and 20.0% or less, P1 is preferably 1.7% or more and 20.0% or less, and preferably 15.0% or less.

[0104] [Other embodiments]

[0105] The present inventors believe that, in addition to the above-mentioned approximate value P1, the parameters related to the slenderness of the anode 3 have an influence on the upper space U1 of the arc tube 1 (see Figure 2B ) affects the flow of gas in the anode 3. Therefore, a parameter P2 is calculated that reflects the parameter related to the slenderness of the anode 3, that is, the ratio of the main body length L1 (mm) to the anode diameter F2 (mm) in the approximate value P1 of the volume ratio.

[0106] Specifically, the parameter P2 is calculated by the following formula (4).

[0107] [Formula 4]

[0108]

[0109] Table 4 shows the results of comparing the parameter P2 with the elevation angle θ1.

[0110] [Table 4]

[0111]

[0112] Figure 5B This is a chart showing Table 2 as a scatter diagram, in which parameter P2 (=[(A1·B1) / (C1·D1)]·[L1 / F2]·100) is set as the horizontal axis, and the elevation angle θ1 is set as the vertical axis. Straight lines T2 and T3 are approximate straight lines of the curve obtained by the least squares method. It can be seen that the value of parameter P2 changes when the elevation angle θ1 is around 50 degrees, and the slope of the approximate straight line changes. As mentioned above, when the elevation angle θ1 is above 50 degrees, it is easy to obtain a blackened area outside the effective utilization angle A1, so parameter P2 is preferably less than 20. That is, by specifying the design range of parameter P2, it is possible to find an area that has a special effect on the elevation angle θ1.

[0113] The above is a description of the embodiment of the lamp 100. The present invention is not limited to the above embodiment, and various changes or improvements can be added to the above embodiment without departing from the gist of the present invention.

[0114] Description of Reference Numerals

[0115] 1: Light-emitting tube;

[0116] 2a: first side pipe;

[0117] 2b: second side tube;

[0118] 3: positive electrode;

[0119] 4: negative electrode;

[0120] 5a: first lead rod;

[0121] 5b: second lead rod;

[0122] 12a, 12b: connector;

[0123] 100: Light;

[0124] A1: Effective use of angles;

[0125] AR: Arc;

[0126] B1: inner diameter of the light-emitting tube;

[0127] Ba1, Ba2: blackened areas;

[0128] U1: upper space;

[0129] m1 to m4: monitoring points;

[0130] θ1: elevation angle;

[0131] θ2: cone angle (of anode).

Claims

1. A short arc mercury lamp, characterized in that: have: cathode; an anode, arranged opposite to the cathode on one axis and having a volume larger than that of the cathode; A light-emitting tube having the cathode and the anode inside and sealed with mercury, and having a rotationally symmetrical shape centered on the one axis; A first side tube formed at an anode side end portion close to the anode among the ends on both sides of the light emitting tube; and A second side tube is formed at a cathode side end portion close to the cathode among the ends of both sides of the light emitting tube, In the cross section passing through the one axis, the following formula (1) is satisfied: [Formula 1] In formula (1), A1 (mm) represents the length in the one axial direction from the closest position of the light-emitting tube to the anode side end of the light-emitting tube, B1 (mm) represents the inner diameter of the light-emitting tube at the closest position, C1 (mm) represents the length in the one axial direction from the anode side end of the light-emitting tube to the cathode side end, and D1 (mm) represents the inner diameter of the light-emitting tube at the most bulging position of the light-emitting tube.

2. The short arc mercury lamp according to claim 1, characterized in that: Satisfies the following formula (2): [Formula 2] In formula (2), A1 (mm) represents the length in the one axial direction from the closest position of the light-emitting tube to the anode side end of the light-emitting tube, B1 (mm) represents the inner diameter of the light-emitting tube at the closest position, C1 (mm) represents the length in the one axial direction from the anode side end of the light-emitting tube to the cathode side end, D1 (mm) represents the inner diameter of the light-emitting tube at the most bulging position of the light-emitting tube, L1 (mm) represents the length in the one axial direction of the anode, and F2 (mm) represents the maximum diameter of the anode.

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