JP2009021023A - Ultra-high pressure mercury lamp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultra-high pressure mercury lamp which is operable by a large power supply and causes no cracking at a sealing part for stable illumination for extended hours. <P>SOLUTION: The ultra-high mercury lamp includes an arc tube consisting of a light-emitting part where a pair of electrodes is arranged to face each other and mercury of specified quantity is sealed, and a sealing part having an oval-like cross section. A part of the electrode axis related to each electrode is jointed to one end side portion of a metal foil embedded airtightly in the sealing part, and a part of an external lead extending from the outer end surface of the sealing part is jointed to the other end side portion of the metal foil. The metal foil has a bent part deflected in arc, which satisfies a specific relationship based on the outside diameter in major axis direction of the sealing part, projection width of the metal foil, and the interval between the straight line connecting both end edges of the metal foil and the inscribed line to the metal foil parallel to the straight line, for the cross section that is orthogonal to the tube axis at the proximity position on the outside in the tube axis direction relative to a base end surface of the electrode axis part. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to an ultra-high pressure mercury lamp, and in particular, a mercury vapor pressure at the time of lighting used as a light source of a projection type projector apparatus such as a liquid crystal projector or a DLP (digital light processor) using a DMD (digital micromirror device). The present invention relates to an ultra-high pressure mercury lamp having a pressure of 150 atmospheres or more.

  2. Description of the Related Art Conventionally, in a projection type projector apparatus represented by, for example, a liquid crystal projector or a DLP using a DMD, an image can be illuminated uniformly and with sufficient color rendering on a rectangular screen. A metal halide lamp in which mercury or a metal halide is enclosed in a tube has been widely used as a light source.

In recent years, there has been a demand for further miniaturization and point light sources for such light sources for projector devices. Instead of metal halide lamps, the mercury vapor pressure during lighting exceeds, for example, 150 atmospheres or more. The use of high-pressure mercury lamps has become mainstream.
If such an ultra-high pressure mercury lamp is used as a light source, since the mercury vapor pressure is extremely high, the spread of the discharge arc can be suppressed, so that the light output can be further improved.

Such an ultra-high pressure mercury lamp will be described with reference to, for example, FIG. 1. A spherical light emitting part (12) having a sealed space inside, and both ends of the light emitting part (12) continuously along the tube axis. A rod-shaped sealing portion (13) extending, for example, comprises an arc tube (11) made of, for example, quartz glass, and a pair of electrodes (20) are disposed opposite to each other in the light emitting portion (12). The electrode (20) of each of the sealing portions (13) extends outward from the outer end surface of the sealing portion (13) through a metal foil (30) embedded in an airtight manner so as to extend along the tube axis. It is electrically connected to an external lead (15) provided so as to protrude and extend.
In this ultra-high pressure mercury lamp, for example, 0.15 mg / mm ³ or more of mercury is sealed in the light emitting section (12), and the mercury vapor pressure in the light emitting section (12) at the time of lighting is 150 atm or more. Is.

Thus, in the ultra-high pressure mercury lamp having the above-described configuration, the pressure in the light emitting part (12) at the time of lighting becomes extremely high, so that the sealed gas escapes or cracks occur in the sealing part (13). In order to avoid such a problem, the glass constituting the sealing part (13), the shaft part of the electrode (20) and the metal foil for power supply (30) are provided. There is a need for sufficient and firm adhesion.
Conventionally, in a state where, for example, quartz glass constituting the arc tube forming material is heated at a high temperature of, for example, 2000 ° C. or higher, the thick quartz glass is gradually contracted to form the sealing portion (13). Thus, in the sealing part (13), the adhesion between the quartz glass and the shaft part of the electrode (20) and the metal foil (30) for feeding is increased.

However, when the glass is baked at a high temperature, the adhesion between the glass and the shaft portion of the electrode (20) and the metal foil (30) is improved, but the sealing portion (13) is likely to be damaged after the lamp is completed. The problem arises.
This is because, in the stage where the temperature of the sealing portion (13) after the heat treatment is gradually lowered, for example, the expansion coefficient of tungsten constituting the electrode (20) is, for example, that of quartz glass constituting the sealing portion (13). This is because a crack is generated at the contact portion between tungsten and quartz glass due to the difference in relative expansion between tungsten and quartz glass because it is larger by one digit or more than the expansion coefficient. In the initial stage, cracks produced during the manufacture of the lamp are very small, but grow as the inside of the light emitting part (12) becomes extremely high when the lamp is turned on, and eventually the lamp is sealed. The part (13) can be a factor of breakage.
Such a problem never occurs in a lamp having a low pressure in the light emitting section (12), but is a specific problem that occurs in a lamp in which the light emitting section (12) is in a high pressure state of 150 atm or higher when lit. .

The present applicant applies the high pressure in the light emitting part when the lamp is turned on to the gap inevitably formed in the vicinity of the joint between the electrode shaft part and the metal foil, and the crack is generated. It is found that the above problem can be solved by making the gap as small as possible. For example, a metal foil 50 having the configuration shown in FIG. An ultra-high pressure mercury lamp in which is formed is proposed (see Patent Document 1).
The configuration of the metal foil 50 relating to the ultrahigh pressure mercury lamp will be specifically described. The metal foil 50 is curved in an arc shape at the center position in the width direction of the strip-shaped metal plate (foil forming material). The groove part 51 is formed and configured to extend in the longitudinal direction, and one end of the curved groove part 51 is one end of a flat plate-like flat part 55 that extends in the width direction continuously to both side edges of the curved groove part 51. A state of projecting outward in the longitudinal direction from the edge, in other words, a state in which the total length of the curved groove portion 51 is larger than the total length of the flat portion 55.
In this metal foil 50, the base end side portion of the electrode shaft portion 65 is separated from the protruding portion 52 of the curved groove portion 51, and the base end surface is spaced outward from the one end edge of the flat portion 55 in the metal foil 50 in the longitudinal direction. In the positioned state, the joint is joined, and the distal end portion of the external lead 66 is joined to the other end of the curved groove 51.
Then, according to the ultrahigh pressure mercury lamp using the metal foil 50 having such a configuration, a gap inevitably generated between the electrode shaft portion 65 and the metal foil 50 (position near the joint portion) is made as much as possible. Since it can be made small, it is described that the occurrence of cracks can be prevented even when a high pressure in the light emitting portion is applied to the gap when the lamp is lit.

Japanese Patent No. 3570414

In recent years, there has been a tendency for the electric power supplied to the lamp to increase in response to the demand for higher output of the ultra-high pressure mercury lamp, and accordingly, even when a large current is passed through the lamp It is necessary to increase the outer diameter of the electrode shaft so that the electrode is not melted.
In the ultrahigh pressure mercury lamp provided with such a metal foil, it is necessary to increase the depth of the curved groove portion 51 as the outer diameter of the electrode shaft portion 65 increases, and the metal foil 50 It is necessary to increase the width dimension of the curved groove portion 51 of the metal foil 50 so as not to melt.

However, by using the metal foil having such a configuration, the sealing work as described above, that is, the part where the sealing part in the arc tube forming material is to be formed is heated from the outer surface side, for example, with a burner or the like, and the glass is heated. When a sealing operation (sealing operation) is performed in which the glass is melted and the electrode shaft portion 65 and the metal foil 50 are brought into close contact with each other, a gap generated between the electrode shaft portion 65 and the metal foil 50 is as much as possible. However, it has been found that the following problems occur.
That is, as shown in FIG. 11 and FIG. 12, in the protruding portion 52 of the curved groove portion 51, the portion located on the outer side from the base end surface of the electrode shaft portion 65 (region surrounded by a broken line in FIG. 11). On the other hand, it was confirmed by visual observation that the glass SA was not sufficiently filled and a gap SA was formed between the glass constituting the sealing portion 60 and the metal foil 50. Moreover, in the sealing part 60 of the lamp | ramp obtained, it was confirmed that the curved groove part 51 of the metal foil 50 has reached to the outer peripheral surface vicinity of the sealing part 60 because it is a thing with a large width dimension.
And when it turned on the ultrahigh pressure mercury lamp of such a structure, it became clear that the problem that a crack arises in the sealing part 60 generate | occur | produces with high frequency.

  The present invention has been made based on the above circumstances, and in an ultra-high pressure mercury lamp configured to be able to input a large amount of power, there is no occurrence of cracks in the sealing portion, and over a long period of time. An object of the present invention is to provide an ultra-high pressure mercury lamp that can be lit stably.

  The present inventor examined the cause of cracks in the sealing portion, and found that the thickness of the quartz glass constituting the sealing portion (from the outer peripheral surface in the radial direction of the sealing portion in the cross section orthogonal to the tube axis) Two factors are the mechanical strength that is determined by the size of the shortest distance up to) and the adhesion strength that is determined by the relationship between the thickness of the quartz glass and the depth of the curved portion that forms the electrode joint in the metal foil. The knowledge that it is related to outbreak was obtained.

The ultra-high pressure mercury lamp of the present invention includes a light emitting part in which a pair of electrodes are arranged opposite to each other and 0.15 mg / mm ³ or more of mercury is sealed, and a tube shaft continuously at both ends of the light emitting part. An arc tube comprising a sealing portion having a substantially elliptical cross-sectional shape extending along
Each electrode has an electrode shaft portion extending along the tube axis, and a proximal end side portion of the metal foil embedded in an airtight manner so that a proximal end portion of the electrode shaft portion extends along the tube axis in the sealing portion In the ultra-high pressure mercury lamp formed by joining the distal end portion of the external lead that is joined to the portion and extending outwardly from the outer end face of the sealing portion in the tube axis direction to the proximal end portion of the metal foil,
Each of the metal foils has at least a curved portion having a cross-sectional shape curved in an arc shape so as to cover a part of the outer surface of the electrode shaft portion in a cross section perpendicular to the tube axis,
In the cross section perpendicular to the tube axis in the vicinity of the tube shaft direction outer side of the sealing portion with respect to the base end surface of the electrode shaft portion, the outer diameter in the major axis direction of the sealing portion is R1, and the metal foil When the distance between the straight line connecting both ends and the inscribed line with respect to the metal foil parallel to the straight line is h, and the projected width of the metal foil in the direction perpendicular to the straight line is R2, the following formulas 1 and 2 are shown. It is characterized by satisfying both of the relations.

In the ultra-high pressure mercury lamp of the present invention, the metal foil has a curved portion formed so as to extend over the entire length in the longitudinal direction at the center position in the width direction of the strip-shaped metal plate, and both side edges of the curved portion. And a flat portion extending in the width direction continuously,
One end side portion of the bending portion protrudes from one end edge of the flat portion, and the base end side portion of the electrode shaft portion can be joined to the protruding portion of the bending portion.

  According to the ultra-high pressure mercury lamp of the present invention, basically, the metal foil has at least a curved portion having a cross-sectional shape curved in an arc shape so as to cover a part of the outer surface of the electrode shaft portion in a cross section perpendicular to the tube axis. By having the configuration, it is possible to configure the gap inevitably formed in the vicinity of the joint between the electrode shaft portion and the metal foil as small as possible, and the curved portion of the metal foil is sealed. Since the glass constituting the part is formed in a state satisfying a predetermined relationship, the electrode shaft part has a large outer diameter so that the electrode shaft part does not melt as the output increases. Even in the portion located on the outer side in the tube axis direction from the base end surface of the electrode shaft portion in the curved portion, the glass can be filled without any gaps, so that the adhesion strength between the glass and the metal foil is high. As well as Since the glass constituting the sealing portion located on both sides of the metal foil has a sufficient thickness, the mechanical strength of the sealing portion can be increased. When the lamp is turned on, it is possible to reliably prevent the occurrence of cracks, and the lamp can be lit stably for a long time.

The present invention will be described below with reference to the drawings.
1 is a cross-sectional view in the tube axis direction showing an outline of the configuration of an example of the ultrahigh pressure mercury lamp of the present invention, and FIG. 2 is a tube axis direction showing the configuration of the sealing portion of the ultrahigh pressure mercury lamp shown in FIG. It is an expanded sectional view.
The ultra-high pressure mercury lamp 10 includes, for example, a substantially spherical light-emitting portion 12 and a rod-shaped sealing portion 13 extending continuously outward from the light-emitting portion 12 in the tube axis direction, such as quartz glass. The arc tube 11 is made of a material that transmits visible light, and the sealing portion 13 is formed by, for example, a shrink seal method and has a substantially elliptical cross-sectional shape.

  A pair of electrodes 20 made of, for example, tungsten are disposed opposite to each other inside the light emitting unit 12, and each electrode 20 is airtight so as to extend in the tube axis direction in each sealing unit 13. It is electrically connected to the external lead 15 that protrudes outward from the outer end surface of the sealing portion 13 and extends through the metal foil 30 made of a conductive material such as molybdenum, which is embedded and disposed. ing. Here, the distance between the electrodes is, for example, 0.5 to 2.0 mm.

In addition, mercury, a rare gas, and a halogen gas are sealed inside the light emitting unit 12.
The amount of mercury enclosed is such that the mercury vapor pressure in the light emitting section 12 during lighting is 150 atmospheric pressure or higher, for example, 0.15 mg / mm ³ or higher. In addition, the mercury vapor pressure at the time of lighting is 200 atmospheres or 300 atmospheres or more of mercury is enclosed, and the mercury vapor pressure at the time of lighting is further increased, so that the light source suitable for the projector apparatus is surely configured. Can do.
The rare gas is for improving the lighting startability, and for example, argon gas is sealed in an amount of 13 kPa.
The halogen gas is used to extend the life of the lamp using the halogen cycle and prevent the light emitting unit 12 from being damaged and devitrified. The amount of the halogen gas is, for example, 10 ⁻⁶ to 10 ⁻² μmol / mm. Within the range of ³ , it is adjusted as appropriate according to the lamp specifications.

As shown in FIG. 3, each of the electrodes 20 includes a rod-shaped electrode shaft portion 25 and an electrode spherical portion 22 having a diameter larger than that of the electrode shaft portion 25 formed at the tip portion of the electrode shaft portion 25. An electrode main body portion 21 comprising a coil portion 23 provided on the base end side of the electrode spherical portion 22 and a projection portion 24 formed at the top (tip) of the electrode spherical portion 22 and on which a discharge arc concentrates during lighting; The electrode spherical portion 22 as a whole protrudes into the sealed space in the light emitting portion 12, and the center axis O of the electrode shaft portion coincides with the tube axis C of the arc tube 11 (FIG. 5). -See A).
The electrode spherical portion 22 is formed by melting a portion located on the tip end side in a state in which a wire made of tungsten is wound around the tip end of the electrode shaft portion 25, and the tip end of the electrode shaft portion 25 is melted. The protrusion 24 is formed by remaining without being formed, and the coil portion 23 is constituted by a part of the tungsten wire remaining without being melted.

  In the ultra-high pressure mercury lamp 10 having such an electrode 20, when AC power is applied between the pair of electrodes 20, dielectric breakdown occurs between the electrodes 20, and the protrusion 24 of each electrode 20 is the starting point. A discharge arc is formed, and light including visible light having a wavelength of 360 to 780 nm, for example, is emitted.

As shown in FIG. 4, each metal foil 30 has a configuration in which a curved groove portion 31 extending in the longitudinal direction is formed in the longitudinal direction at the center position in the width direction of the strip-shaped metal plate (foil forming material). The curved groove portion 31 protrudes outward in the longitudinal direction from one end edge of the flat plate-like flat portion 35 whose one end portion in the longitudinal direction extends in the width direction continuously to both side edges of the curved groove portion 31. It is supposed to be in a state to do.
The curved groove portion 31 is preferably configured to have an arcuate cross-sectional shape that follows a part of a circle larger than the outer diameter of the electrode shaft portion 25 and the external lead 15 having the same outer diameter, for example. Specifically, for example, the curved groove portion 31 can have a shape that follows a part of a circle having a diameter that is about 5 to 100% larger than the diameter of the electrode shaft portion 25.
Thus, by having the flat part 35 in the both sides in the width direction of the metal foil 30, it is possible to obtain a sufficient strength against the twist generated during the sealing operation, and the metal foil 30 can be sealed without being deformed. It is possible to reliably seal at a predetermined position in the portion 13.

In this metal foil 30, a part of the outer peripheral surface of the proximal end side portion of the electrode shaft portion 25 is joined to the bottom surface of the distal end side region of the protruding portion 32 of the curved groove portion 31 by, for example, spot welding or the like. A part of the outer peripheral surface at the tip side portion of the external lead 15 is joined to the bottom surface of the other end side region of the groove 31 by, for example, spot welding.
As shown in FIGS. 5A and 5B, the gap S is inevitably formed in the vicinity of the joint between the electrode shaft portion 25 and the metal foil 30, but the curve formed in the metal foil 30. By joining the electrode shaft portion 25 and the external lead 15 to the groove portion 31, the gap S between the metal foil 30 and the electrode shaft portion 25 can be reduced, and the sealing portion is formed by a shrink seal method. The stress generated when the metal foil 30 is sealed with respect to the glass constituting the glass 13 can be canceled, and the adhesion between the glass and the metal foil 30 can be strengthened.

Furthermore, by the configuration shown in the following (A) to (C), the size of the gap S can be made as small as possible, and even when a high voltage is applied during lighting. It is possible to reliably prevent the occurrence of cracks.
In the cross section obtained by cutting the portion corresponding to the joint between the electrode shaft portion 25 and the metal foil 30 in the sealing portion 13 in the direction orthogonal to the tube axis,
(A) Configuration in which a region in the range of 5 to 50% of the diameter of the electrode shaft portion 25 is covered with the curved groove portion 31 of the metal foil 30;
(B) When the total circumferential length of the outer peripheral surface region of the electrode shaft portion 25 facing the gap S is X (x1 + x2) and the circumferential length of the electrode shaft portion 25 is Y, the value of X / Y is 0.05 to 0. A configuration within the range of .5,
(C) When Z (z1 + z2) is the entire circumference of the outer peripheral surface area of the metal foil facing the gap S, and R2 is the maximum projection width of the metal foil 30 in the direction orthogonal to the tube axis (see FIG. 6). , Z / R2 value is in the range of 1.0 to 3.1.

The metal foil 30 having such a configuration has, for example, a strip-shaped wide portion and a small width portion having a smaller width dimension than the wide portion continuously extending to the center position on the front end side of the wide portion. It can be obtained by performing groove processing on the foil forming material formed in a strip shape over the entire length in the length direction of the central portion of the narrow portion and the wide portion continuous therewith, for example, by a press machine or the like. .
By forming such a metal foil 30 in advance, there is no concern that the electrode shaft portion 25 and the external lead 15 are eccentrically arranged when the ultrahigh pressure mercury lamp 10 is manufactured. And the external lead 15 can be reliably joined to the predetermined position of the metal foil 30.

In the ultra high pressure mercury lamp 10, the glass and metal foil constituting the sealing portion 13 are adjusted by adjusting the thickness of the glass constituting the sealing portion 13 and the depth of the curved groove portion 31 in the metal foil 30 described later. The sealing portion 13 is formed so that the adhesion strength with the portion 30 and the mechanical strength of the sealing portion 13 are sufficiently high.
That is, as shown in FIG. 6, in the cross section orthogonal to the tube axis at a position near the tube axis direction outer side with respect to the base end surface of the electrode shaft portion, the long axis direction of the sealing portion 13 whose cross-sectional shape is substantially elliptical , That is, when the sealing portion 13 is sandwiched between two parallel lines, the outer diameter at which the interval between the parallel lines becomes the maximum is “the outer diameter R1 of the sealing portion”, and both edge portions of the curved groove 31 The dimension that maximizes the distance between the straight line L1 that connects the straight line L1 and the inscribed line L2 that is in contact with the bottom surface of the curved groove part 31 parallel to the straight line L1 is “the depth h of the curved groove part 31”. When the projection width in the direction perpendicular to L1 is “projection width R2 of the curved groove portion 31”, both of the relations expressed by the above formulas 1 and 2 are satisfied.

The above formula 1 that defines the ratio of the projection width R2 of the curved groove 31 in the metal foil 30 to the outer diameter R1 of the sealing portion 13 is the level position where the thickness of the glass constituting the sealing portion 13 is minimized. (In this embodiment, at the level position where the both edge portions of the curved groove portion 31 are positioned), the thickness of the glass between one end edge portion of the curved groove portion 31 and the outer peripheral surface of the sealing portion 13 is defined as t1. , The thickness of the glass between the other edge of the curved groove 31 and the outer peripheral surface of the sealing portion 13 is t2 (however, the metal foil 30 is located in the center in the sealing portion 13 (t1 = T2)), it is rewritten as t1 (t2)> R1 / 4, that is, the mechanical strength of the sealing portion 13 based on the thickness of the glass.
When the value of R1 / R2 is 2 or less, that is, when the outer diameter R1 of the sealing portion 13 is approximately the same as the projection width R2 of the curved groove portion 31, the outer peripheral surface of the sealing portion 13 The metal foil 30 reaches the vicinity, the thickness (t1 and t2) of the quartz glass in the sealing portion 13 is reduced, and the mechanical strength of the sealing portion 13 is reduced.
On the other hand, when the outer diameter R1 of the sealing portion 13 is excessive with respect to the projection width R2 of the curved groove portion 31, the thickness of the quartz glass in the sealing portion 13 is increased, and the mechanical properties of the sealing portion 13 are increased. Although the strength is expected to be improved, if the curved groove portion 31 of the metal foil 30 has an extremely deep structure in an attempt to reduce the projection width R2 of the curved groove portion 31, as will be described later, This is not preferable because the adhesion strength is lowered.
Therefore, the value of R1 / R2, which is the ratio between the outer diameter R1 of the sealing portion 13 and the projection width R2 of the curved groove portion 31, is an appropriate value in relation to the adhesion strength between the glass and the metal foil 30 described later, that is, By adjusting to be larger than 2, preferably 7.0 to 10.0, a sufficiently high mechanical strength can be obtained.

In the above formula 2, the factor represented by [(R1-R2) / h] is the degree of ease of glass entering into the curved groove portion 31 of the metal foil 30 when performing the sealing work by the shrink seal method, that is, This relates to the adhesion strength between the glass constituting the sealing portion 13 and the metal foil 30.
The adhesion strength of the sealing portion 13 will be specifically described. When the electrode 20 having a large diameter of the electrode shaft portion 25 is used as the output of the ultrahigh pressure mercury lamp 10 is increased, as described above. In order to ensure sufficient mechanical strength, the glass thickness (t1, t2) must be increased.
However, when the thickness of the glass in the sealing portion 13 is increased, the temperature of the glass near the metal foil 30 is lower than the temperature of the glass near the outer peripheral surface of the sealing portion 13 so that the glass is difficult to flow. Therefore, when the depth 31 of the curved groove portion of the metal foil 30 is large, the glass filling into the curved groove portion 31 is hindered.
On the other hand, if the depth h of the curved groove portion 31 is reduced with respect to the thickness of the glass in the sealing portion 13, the filling of the glass into the curved groove portion 31 becomes difficult to be hindered, so that the curved groove portion 31 is completely filled with glass. As a result, it is expected that the adhesion strength between the glass and the metal foil 30 in the sealing portion 13 is improved. However, the depth h of the curved groove portion 31 is extremely large with respect to the thickness of the glass in the sealing portion 13. When the metal foil 30 having a small configuration is used, it is difficult to obtain the effect of preventing the occurrence of cracks by reducing the gap S generated in the vicinity of the joint between the metal foil 30 and the electrode shaft portion 25. .
Therefore, by adjusting the depth h of the curved groove 31 to an appropriate size so as not to be too large or too small with respect to the thickness of the quartz glass in the sealing portion 13, it is sufficiently high. Adhesion strength can be obtained.

In the ultrahigh pressure mercury lamp 10 in this embodiment, as shown in FIG. 5-A, the electrode shaft portion 25 has a central axis O radially outward from both ends of the curved groove portion 31 (in FIG. 5-A). It is preferable that the structure is arranged so as to be positioned at the level position on the upper side.
By setting it as such a structure, the depth h of the curved groove part 31 with respect to the thickness of the glass in the sealing part 13 can be set in the optimal range with which sufficient adhesive strength is obtained.

As is apparent from the above description, the above equation 2 is expressed by the product of a factor related to the mechanical strength of the sealing portion 13 and a factor related to the adhesion strength between the glass and the metal foil 30 in the sealing portion 13. This relates to the strength (pressure resistance) of the entire sealing portion 13.
That is, for example, even if one of the mechanical strength and the adhesion strength is relatively low, if the other has a sufficiently high strength, the shortage of one strength is complemented by the other strength. As a whole, the sealing part 13 means that sufficient strength required to prevent the occurrence of cracks and the rupture of the arc tube 11 due to the cracks can be obtained.
As apparent from the results of the experimental examples described later, the product of the factor related to mechanical strength and the factor related to adhesion strength is 80 or more, so that the sealing portion 13 is configured to have sufficiently high strength. be able to.

  In the above, it is preferable that the depth h (see FIG. 6) of the curved groove portion 31 in the metal foil 30 is uniform in the longitudinal direction. Since the depth h of the curved groove portion 31 is uniform in the longitudinal direction, the electrode shaft portion 25 and the external lead 15 having the same outer diameter can be disposed coaxially. The shaft portion 25 and the external lead 15 can be reliably arranged at predetermined positions without being eccentric.

  The ultra high pressure mercury lamp 10 according to the present invention is driven to be lit with a large power of, for example, 250 to 350 W, and a large current of, for example, 2.0 to 7.0 A is supplied to the electrode 20. For example, the outer diameter R1 of the sealing portion 13 is 6.6 to 7.4 mm, and the projected width R2 of the curved groove portion 31 of the metal foil 30 is 0.7 to 0.7, for example. 1.0 mm, the depth h of the curved groove portion 31 of the metal foil 30 is 0.2 to 0.6 mm, and the outer diameter of the proximal end portion of the electrode shaft portion 25 is φ0.4 to 1.0 mm.

Thus, according to the ultra-high pressure mercury lamp 10 having the above-described configuration, basically, the electrode shaft portion 25 and the curved metal foil 30 that is curved in an arc shape so as to cover a part of the outer peripheral surface of the electrode shaft portion 25. Since the groove portion 31 is joined, the gap S inevitably formed in the vicinity of the joint portion between the electrode shaft portion 25 and the metal foil 30 can be configured to be as small as possible. In addition, since the curved groove portion 31 of the metal foil 30 is formed in a state satisfying the above specific relationship with respect to the glass constituting the sealing portion 13, large power can be input, and the electrode shaft portion 25 is Even if the electrode shaft portion 25 has a large diameter so as not to melt, it is sealed in the curved groove portion 31 of the metal foil 30 positioned on the proximal side in the tube axis direction from the proximal end surface of the electrode shaft portion 25. The glass constituting the stopper 13 can be filled without any gaps. Therefore, the adhesion strength between the glass and the metal foil 30 can be increased, and a sufficient thickness is ensured for the glass constituting the sealing portion 13 located on both sides of the metal foil 30. Therefore, the mechanical strength of the sealing portion 13 can be increased, and therefore, cracks can be reliably prevented from occurring when the ultrahigh pressure mercury lamp 10 is turned on. It will be able to light stably over time.
In particular, the electrode shaft portion 25 has a large outer diameter of φ0.4 to 1.0 mm, and is extremely useful in a configuration in which a large power of 250 to 350 W is input to the electrode 20 and used. It is.

<Experimental example>
Hereinafter, experimental examples performed for confirming the effects of the present invention will be described.
According to the configuration of the ultra-high pressure mercury lamp shown in FIGS. 1 to 6, the outer diameter R1 of the sealing portion, the projection width R2 of the curved groove portion in the metal foil, and the depth h of the curved groove portion in the metal foil are as shown in Tables 1 and 2 below. Five modified ultra-high pressure mercury lamps were produced based on the following specifications.
The arc tube has a maximum outer diameter of the light emitting part of 12.0 mm, a total length of the light emitting part of 9.8 mm, a length of the sealing part of 22 mm, and the sealing part is formed by a shrink seal method.
The total length of the electrode including the electrode main body is 11 mm, and the outer diameter of the electrode shaft is φ0.7 mm.
The metal foil has a total length in the tube axis direction of 14 mm (the length of the protruding portion is 3.0 mm) and a thickness of 25 μm, and the length of the region of the protruding portion in the curved groove portion on the proximal side from the proximal end surface of the electrode shaft portion The distance (the distance from the base end surface of the electrode shaft portion to the tip edge of the flat portion) is 1.5 mm.
The enclosed amount of mercury is 0.15 mg / mm ³ , the enclosed amount of argon gas (rare gas) is 13 kPa, and the enclosed amount of halogen gas is 3.0 μmol / mm ³ .
For each of the lamps thus obtained, one cycle of the operation of turning on continuously for 3.5 hours and then turning off for 0.5 hours under the lighting conditions of lamp power of 300 W and applied current of 4.3 A. As follows, after conducting a lighting test (life test) that is repeated 125 cycles (integrated value of lighting time is 500 hours), the state of the sealing portion is visually confirmed, and cracks increase compared to the initial lighting time. In the case where at least one of the five lamps that were (growing) or damaged was evaluated, “×” was evaluated, and the case where none was present was evaluated as “◯”. The results are shown in Tables 1 and 2.

  As is apparent from the above results, according to the ultrahigh pressure mercury lamp according to the present invention that satisfies both the relations of the above formulas 1 and 2, it is possible to reliably prevent cracks from occurring when the lamp is lit. It was confirmed that the lamp can be lit stably over time.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment.
FIG. 7 is an enlarged sectional view in the tube axis direction showing the configuration of the sealing portion in another example of the ultrahigh pressure mercury lamp of the present invention, FIG. 8 is a sectional view taken along the line CC in FIG. 7, and FIG. It is a perspective view which shows the structure of the metal foil which concerns on the ultrahigh pressure mercury lamp shown in FIG. 7 with an electrode axial part and an external lead.
This ultra high pressure mercury lamp has the same configuration as that of the ultra high pressure mercury lamp shown in FIG. 1 except for the metal foil, and the configuration of the metal foil will be specifically described below.
The metal foil 40 according to this ultra-high pressure mercury lamp has a bowl shape in which the cross-sectional shape in the direction orthogonal to the tube axis is an arc shape, and the electrode shaft portion 25 is formed on the inner surface on one end side in the longitudinal direction. A part of the outer peripheral surface in the proximal end portion is joined, and a part of the outer peripheral surface in the distal end portion of the external lead 15 is joined to the inner surface on the other end side.

Also in the sealing part of the ultra-high pressure mercury lamp using such a metal foil 40, the thickness of the glass constituting the sealing part 13 and the depth of the metal foil 40 are adjusted, and the glass in the sealing part 13 The adhesive strength with the metal foil 40 and the mechanical strength of the sealing portion 13 are sufficiently high.
That is, as shown in FIG. 9, the outer diameter of the sealing portion 13 is set to R1 in a cross section orthogonal to the tube axis at a position in the vicinity of the base end surface of the electrode shaft portion 25 on the outer side in the tube axis direction. When the projected width of the metal foil 40 is R2 and the depth of the metal foil 40 is h, the structure satisfies both of the relations expressed by the above formulas 1 and 2. The outer diameter of the sealing portion 13 is defined as R1, the projected width of the metal foil 40 is defined as R2, and the depth of the metal foil 40 is defined as in the configuration shown in FIG.

  Thus, according to the ultra high pressure mercury lamp having the above configuration, substantially the same effect as that of the above configuration, that is, the gap inevitably formed in the vicinity of the joint portion between the electrode shaft portion 25 and the metal foil 40. S can be configured to be as small as possible, and a large electric power can be input, and the diameter of the electrode shaft portion 25 is large so that the electrode shaft portion 25 does not melt. In addition, the adhesion strength between the glass and the metal foil 40 can be increased, and the mechanical strength of the sealing portion 13 can be increased. Therefore, when the ultrahigh pressure mercury lamp 10 is turned on, It is possible to reliably prevent the occurrence of cracks, and to stably illuminate for a long time.

It is sectional drawing of the pipe-axis direction which shows the outline of a structure in an example of the ultrahigh pressure mercury lamp of this invention. FIG. 2 is an enlarged cross-sectional view in the tube axis direction showing a configuration of a sealing portion of the extra-high pressure mercury lamp shown in FIG. 1. It is an enlarged view which shows the structure of the electrode of the ultrahigh pressure mercury lamp shown in FIG. It is a perspective view which shows typically the structure of the metal foil of the ultrahigh pressure mercury lamp shown in FIG. 1 with an electrode axial part and an external lead. It is the sectional view on the AA line in FIG. It is sectional drawing which expands and shows a part of FIG. 5-A. It is the BB sectional view taken on the line in FIG. It is an expanded sectional view of the direction of a tube axis which shows the composition of the sealing part in other examples of the super high pressure mercury lamp of the present invention. It is CC sectional view taken on the line in FIG. It is a perspective view which shows the structure of the metal foil which concerns on the ultrahigh pressure mercury lamp shown in FIG. 7 with an electrode axial part and an external lead. It is a perspective view which shows typically the structure of the metal foil which concerns on the conventional ultrahigh pressure mercury lamp with an electrode axial part and an external lead. It is an expanded sectional view of the direction of a tube axis which shows the composition of the sealing part in an example of the conventional super-high pressure mercury lamp. It is the DD sectional view taken on the line in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Super high pressure mercury lamp 11 Light emission tube 12 Light emission part 13 Sealing part 15 External lead 20 Electrode 21 Electrode main body part 22 Electrode spherical part 23 Coil part 24 Projection part 25 Electrode axial part 30 Metal foil 31 Curved groove part 32 Projection part 35 Flat part 40 Metal foil S Cavity O Center axis of electrode shaft portion C Tube axis of arc tube 50 Metal foil 51 Curved groove portion 52 Projection portion 55 Flat portion 60 Sealing portion 65 Electrode shaft portion 66 External lead SA Gap

Claims (2)

A light emitting part in which a pair of electrodes are arranged opposite to each other and 0.15 mg / mm ³ or more of mercury is sealed, and a substantially elliptical cross section extending along the tube axis continuously at both ends of the light emitting part. An arc tube comprising a sealing part having a shape,
Each electrode has an electrode shaft portion extending along the tube axis, and a proximal end side portion of the metal foil embedded in an airtight manner so that a proximal end portion of the electrode shaft portion extends along the tube axis in the sealing portion In the ultra-high pressure mercury lamp formed by joining the distal end portion of the external lead that is joined to the portion and extending outwardly from the outer end face of the sealing portion in the tube axis direction to the proximal end portion of the metal foil,
Each of the metal foils has at least a curved portion having a cross-sectional shape curved in an arc shape so as to cover a part of the outer surface of the electrode shaft portion in a cross section perpendicular to the tube axis,
In the cross section perpendicular to the tube axis in the vicinity of the tube shaft direction outer side of the sealing portion with respect to the base end surface of the electrode shaft portion, the outer diameter in the major axis direction of the sealing portion is R1, and the metal foil When the distance between the straight line connecting both ends and the inscribed line with respect to the metal foil parallel to the straight line is h, and the projected width of the metal foil in the direction perpendicular to the straight line is R2, the following formulas 1 and 2 are shown. An ultra high pressure mercury lamp characterized by satisfying both

The metal foil has a curved portion formed so as to extend over the entire length in the longitudinal direction at the center position in the width direction of the strip-shaped metal plate, and a flat portion extending in the width direction continuously to both side edges of the curved portion. And
The one end side part of the said bending part protrudes from the one end edge of a flat part, and the base end side part of an electrode shaft part is joined in the protrusion part of the said bending part. Super high pressure mercury lamp.

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