JP5040577B2 - Super high pressure discharge lamp - Google Patents

Description

The present invention relates to an ultra-high pressure discharge lamp used in a projector device such as a liquid crystal display device or a DLP (digital light processor: registered trademark) using a DMD (digital mirror device: registered trademark), and particularly 0.15 mg. The present invention relates to an ultrahigh pressure discharge lamp in which mercury of / mm ³ or more is enclosed in an arc tube and the mercury vapor pressure during lighting is 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 discharge 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 discharge lamp is composed of a spherical light emitting portion having a sealed space inside and a rod-shaped sealing portion extending along the tube axis continuously at both ends of the light emitting portion, for example, made of quartz glass. A metal comprising an arc tube, a pair of electrodes made of tungsten, for example, facing each other in the light emitting portion, and each electrode being hermetically embedded so as to extend along the tube axis in each sealing portion It is electrically connected to an external lead provided so as to protrude outward from the outer end surface of the sealing portion through the foil.

  Thus, for example, an ultra-high pressure discharge lamp that is used as a light source for a projector is repeatedly turned on and off, resulting in a difference in thermal expansion coefficient between the electrode material and the arc tube material when the lamp is turned on and off. Thus, it is known that stress is easily generated in the sealing portion and the pressure resistance of the ultrahigh pressure discharge lamp is lowered.

Various measures for improving the pressure resistance of the ultrahigh pressure discharge lamp have been taken against such a problem. Specifically, for example, as shown in FIG. Then, in order to relieve stress generated in the constituent material of the arc tube 42, for example, quartz glass, an ultra-high pressure discharge lamp having a configuration in which the coil member 41 is wound around the rod-shaped electrode portion embedded in the sealing portion 43 of the electrode 40. Has been proposed (see Patent Document 1).
According to the super high pressure discharge lamp having such a configuration, the electrode member and the quartz glass are configured not to be in direct contact with each other, thereby relieving the stress caused by the expansion and contraction of the electrode 40 at the time of lighting and extinguishing. It is supposed to be possible.

  Further, as a technique for relieving the stress generated in the arc tube material due to the expansion and contraction of the electrode, for example, as shown in FIG. 9, the electrode 45 is joined to the metal foil 48 from the tip side holding the arc discharge. In this case, a taper portion 46 having a diameter that gradually decreases toward the rear end portion is used. The minimum inner diameter portion of the arc tube 50 at the boundary portion where the taper portion 46 extends from the sealing portion 52 to the light emitting portion 51. The electrode 45 is positioned corresponding to P, and a relatively large gap is formed between the tapered portion 46 and the glass member, so that the electrode 45 expands and contracts during lighting and extinguishing. However, there has been proposed an ultrahigh pressure discharge lamp having a structure in which the electrode 45 is in contact with the inner surface of the arc tube 50 and stress is prevented from being generated in the arc tube 50 (sealing portion 52) (Patent Document 2). Irradiation).

JP-A-11-176385 JP 2004-55438 A

However, in the above-described conventional ultra-high pressure discharge lamp, when lighting and extinguishing are repeated, the electrode bends greatly at a position corresponding to the minimum inner diameter portion of the arc tube at the boundary portion from the sealing portion to the light emitting portion. It has been found that a problem arises that the electrode may break.
Further, it has been found that there is a problem in that the ultra high pressure discharge lamp itself may be ruptured at the minimum inner diameter portion of the arc tube at the boundary portion from the sealing portion to the light emitting portion.

  The present invention has been made based on the above circumstances, and the expected performance is stable over a long period of time without rupture of the ultra high pressure discharge lamp itself or bending (deformation) of the electrode. It is an object of the present invention to provide an ultra-high pressure discharge lamp that can be obtained in a practical manner.

The ultra-high pressure discharge lamp of the present invention includes a light emitting part having a substantially spherical shape or a substantially elliptical sphere shape that forms a discharge space in which a pair of electrodes are opposed to each other and 0.15 mg / mm ³ or more of mercury is enclosed. A light emitting tube comprising a rod-shaped sealing portion extending along the tube axis continuously to both ends of the light emitting portion,
Each electrode has an electrode shaft portion extending along the tube axis, and a base end side portion of the electrode shaft portion is bonded to a metal foil embedded in an airtight manner so as to extend along the tube axis in the sealing portion. In the ultra high pressure discharge lamp
The electrode shaft portion of at least one of the electrodes has a larger outer diameter toward the outer side in the axial direction at the position of the minimum inner diameter portion that is the end portion on the sealing portion side of the inner surface of the light emitting portion forming the discharge space of the arc tube. It has the taper part which becomes.

In the ultrahigh pressure discharge lamp of the present invention, the taper portion of the electrode shaft portion is formed so that the outer diameter is uniformly increased toward the outer side in the axial direction, and the ridge line in the cross section including the central axis of the electrode The angle A with respect to the central axis of the electrode is preferably in the range of 0.2 ° ≦ A ≦ 8 °.

According to the ultrahigh pressure discharge lamp of the present invention, at least one of the electrodes has an outer diameter toward the axially outward side at a position corresponding to the minimum inner diameter portion of the arc tube at the boundary portion from the sealing portion to the light emitting portion. In the process where the electrode that is in a thermally expanded state at the time of lighting contracts when the lamp is extinguished, the surface of the electrode is caused by the action of the tapered surface. Since it is contracted in the radial direction and the axial direction so as to be separated from the inner surface of the smallest inner diameter portion of the arc tube, it is possible to prevent the contraction (shape restoration) of the electrode from being hindered by the arc tube, and at the time of lighting Even when the electrode is in thermal contact with the inner surface of the arc tube, the electrode can be easily detached from the arc tube by the action of the tapered surface when the lamp is extinguished. That result, it is possible to reliably prevent the electrode bending occurs.
In addition, since it is possible to reliably prevent the outer surface of the tapered portion of the electrode and the inner surface of the arc tube from being in thermal contact with each other, the lighting and extinguishing operations are repeated. However, it is possible to reliably prevent cracks from occurring in the sealing portion and the ultrahigh pressure discharge lamp itself from rupturing, so that the desired performance can be stably obtained over a long period of time.

FIG. 1 is a cross-sectional view showing an outline of the configuration of an example of an ultrahigh pressure discharge lamp according to the present invention, and FIG. 2 is an enlarged cross-sectional view showing a part of the ultrahigh pressure discharge lamp shown in FIG.
The ultra-high pressure discharge lamp 10 has, for example, a substantially spherical or substantially elliptical light-emitting portion 12 that forms a discharge space therein, and a rod-like shape that extends continuously outward in the tube axis direction at both ends of the light-emitting portion 12. The arc tube 11 made of, for example, quartz glass is provided. The seal portion 13 is formed by, for example, a shrink seal method.

  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. Electricity is supplied to the external leads 15 that protrude and extend outward from the outer end surface of the sealing portion 13 through the strip-shaped metal foil 18 made of a conductive material such as molybdenum, which is embedded and disposed. Connected. Here, the distance between 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.

Each electrode 20 is formed, for example, by cutting a rod-shaped electrode material. The electrode body 21 is formed with a coil portion 22, and the electrode body portion 21 is continuously axially outward. And an electrode shaft portion 25 extending in the vertical direction.
The electrode shaft portion 25 includes a rod-shaped tip end portion 26, a taper portion 27 that continues to the tip end portion 26, and has an outer diameter that increases uniformly toward the outer side in the axial direction. 27 and a rod-like proximal end portion 28.
Each electrode 20 is in a state where the tapered portion 27 of the electrode shaft portion 25 corresponds to the position P of the smallest inner diameter portion of the arc tube 11 at least in the boundary portion from the sealing portion 13 to the light emitting portion 12. The position P of the minimum inner diameter portion is disposed in a state where the position P is located on the tapered portion 27 of the electrode shaft portion 25.
Specifically, in consideration of the axial expansion amount (elongation) of the electrode during lighting, the minimum inner diameter of the arc tube 11 at the boundary portion where the tapered portion 27 of the electrode shaft portion 25 extends from the sealing portion 13 to the light emitting portion 12 is considered. It is preferable to be positioned so as to correspond to a region having a length of 0.5 mm including the position P of the part.

The angle A of the tapered portion 27 in the electrode shaft portion 25 with respect to the central axis of the electrode 20 is preferably in the range of 0.2 ° ≦ A ≦ 8 °, for example. When the angle A is within the above angle range, it is possible to reliably prevent the electrode from bending and the arc tube 11 from bursting. On the other hand, when the angle A is larger than 8 °, the arc tube 11 is easily ruptured, and when the angle A is smaller than 0.2 °, the electrode is likely to be bent.

  An example of numerical values relating to the other components of the electrode 20 of the ultrahigh pressure discharge lamp 10 will be described below. For example, in the case of an ultrahigh pressure discharge lamp having a lamp power of 100 to 300 W, the base end side portion 28 of the electrode shaft portion 25 The outer diameter D1 and the outer diameter D2 of the distal end side portion 26 are not particularly limited as long as the opening angle A of the tapered portion 27 is set so as to satisfy the above angle range. The outer diameter D1 of the electrode 28 is in the range of 0.4 to 0.8 mm, the outer diameter D2 of the distal end portion 26 is in the range of 0.35 to 0.78 mm, and the length of the proximal end portion 28 in the electrode shaft portion 25 is, for example, The range of 0.5 to 3.0 mm, the length of the tip side portion 26 in the electrode shaft portion 25 is, for example, in the range of 0.5 to 3.0 mm, and the length L of the tapered portion 27 of the electrode shaft portion 25 is, for example, In the range of 0.5-2.9 mm, Range of outside diameter for example 1.0~3.0mm pole body portion 21 in the range, for example of 2.5~5.0mm length.

  Thus, when the ultrahigh pressure discharge lamp as described above is turned on, as shown in FIG. 3, the electrode 20 expands in the radial direction and also in the axial direction mainly in the light emitting portion direction (inward in the axial direction). Whereas the arc tube 11 expands, the thermal expansion coefficient of its constituent material, for example, quartz glass is much smaller than that of, for example, tungsten, which constitutes the electrode 20, so that it hardly expands compared to the electrode 20. Since the shape is maintained, the electrode 20 expands to the inner surface of the arc tube 11, particularly at the innermost position P of the boundary portion from the sealing portion 13 to the light emitting portion 12. When the electrode 20 is contracted when the ultra-high pressure discharge lamp is extinguished after contact, a part of the electrode 20 is contracted. By turning on and off is repeated executed, the expansion of the electrode 20, cracks moiety the adhesion due to the stress generated in the arc tube 11 by shrinkage which may lead to rupture occurred.

However, at the position P corresponding to the minimum inner diameter portion of the arc tube 11 at the boundary portion from the sealing portion 13 to the light emitting portion 12, the electrode 20 has a taper in which the outer diameter increases uniformly toward the outer side in the axial direction. With the configuration having the portion 27, according to the ultrahigh pressure discharge lamp 10 having the above-described configuration, the electrode 20 which is in a thermally expanded state during lighting contracts during the process of extinguishing the light by the action of the tapered surface. Since the surface of 20 is contracted in the radial direction and the axial direction so as to be separated from the inner surface of the minimum diameter portion of the arc tube 11, the contraction (shape restoration) of the electrode 20 is prevented from being hindered by the arc tube 11. In addition, even when the electrode 20 is in thermal contact with the arc tube 11 during lighting, when the lamp is turned off, the electrode 20 is generated by the action of the tapered surface. Results that can be easily peeled off from the tube 11, it is possible to reliably prevent the electrode bending occurs.
In addition, since it is possible to reliably prevent the outer surface of the tapered portion 27 of the electrode 20 and the inner surface of the arc tube 11 from being in thermal contact, it is possible to turn on and off repeatedly. Even if it exists, it can prevent reliably that a crack generate | occur | produces in the sealing part 13 and an ultrahigh pressure discharge lamp 10 itself bursts, Therefore, desired performance can be obtained stably over a long period of time. .

Hereinafter, experimental examples performed for confirming the effects of the present invention will be described.
According to the configuration of the ultrahigh pressure mercury lamp shown in FIG. 1, the outer diameter D1 of the proximal end portion of the electrode shaft portion, the outer diameter D2 of the distal end portion of the electrode shaft portion, the length L of the tapered portion of the electrode shaft portion, and the electrode shaft Based on the following specifications, a total of 100 ultra-high pressure discharge lamps of 20 types in which the angle A of the taper part of the part was changed according to the following Table 1 were produced.

<Lamp basic specifications>
The arc tube has a maximum outer diameter of the light emitting part of 12 mm, an entire length of the light emitting part of 12 mm, an inner volume of the light emitting part of 137 mm ³ , an outer diameter of the sealing part of 5.7 mm, and a length of the sealing part of 22 mm. .
The electrode has a length of the proximal end portion of the electrode shaft portion of 0.6 mm, a length of the distal end portion of the electrode shaft portion of 0.5 mm, an outer diameter of the electrode body portion of 1.8 mm, and a length of the electrode body portion Is 8.0 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 .
The sealing part is formed by the shrink seal method, and the 0.5 mm long region including the minimum inner diameter part of the arc tube at the boundary part from the sealing part to the light emitting part corresponds to the taper part of the electrode. It is formed to do.

Each of the ultrahigh pressure discharge lamps thus obtained was subjected to a lighting test in which the operation of turning on continuously for 15 minutes and then turning off for 15 minutes at the lighting power shown in Table 1 was repeated 500 times. By performing, the presence or absence of the occurrence of electrode bending was examined. The results are shown in Table 1 below.
For the evaluation of electrode bending, it is determined that “electrode bending” has occurred when the electrode tip position has changed by 1.0 mm or more before and after the test. For each lamp group, the number of lamps in which electrode bending has occurred is determined. As a result of the investigation, “◯” indicates that no electrode bending occurred, “Δ” indicates occurrence of two or less electrode bendings, and “x” indicates that three or more electrode bendings occurred.

In addition, for each of the above ultra-high pressure discharge lamps, by performing a lighting test in which the lighting power shown in Table 1 below is continuously turned on for 15 minutes and then turned off for 15 minutes. The presence or absence of rupture was examined. The results are shown in Table 1 below. Regarding the rupture, “◯” indicates that no rupture occurred, “Δ” indicates that two or less ruptures occurred, and “x” indicates that three or more ruptures occurred.
In the above, regarding the evaluation level of the ultra-high pressure discharge lamp, the evaluation was “x” when the evaluation of either the occurrence of electrode bending or the burst was “x”.

As is clear from the above experimental results, the ultrahigh pressure discharge lamps (lamp groups 1 to 2) according to the present invention having a configuration (D1> D2) in which the outer diameter of the electrode increases as it goes outward in the axial direction. 16) It was confirmed that the occurrence of electrode bending can be prevented.
In the ultrahigh pressure discharge lamps (lamp groups 1 to 16) having a tapered portion whose outer diameter increases as the electrode moves outward in the axial direction, the angle A of the tapered portion is further 0.2 ° ≦ A ≦. It was confirmed that, when the angle is 8 ° (lamp groups 5 to 16), it is possible to prevent the occurrence of electrode bending and to prevent the occurrence of rupture.
On the other hand, an ultra high pressure discharge lamp (lamps 17 and 18) having a configuration in which the electrode does not have a tapered portion, that is, a configuration having a uniform outer diameter in the axial direction (D1 = D2), and the electrode It was confirmed that the ultra high pressure discharge lamps (lamps 19 and 20) having a tapered portion (D1 <D2) having an outer diameter that decreases in the axial direction outwardly cause electrode bending. The reason why the “electrode bending” occurs in the lamps in the lamp groups 17 to 20 is considered to be because the contraction of the electrodes is hindered by the arc tube when the lamp is turned off.

As mentioned above, although embodiment of this invention was described, this invention is not limited to said embodiment, A various change can be added.
For example, the electrode is even shaped to have a tapered portion whose outer diameter increases toward the outer side in the axial direction at a position corresponding to the smallest inner diameter portion of the arc tube at the boundary portion from the sealing portion to the light emitting portion. If it is, it will not be limited to the thing of the shape which concerns on the said embodiment, For example, even if it is a thing shown in FIG. 4 and FIG. 5, the effect similar to the said Example can be acquired.

The tapered portion 27 of the electrode 20 shown in FIG. 4 has a shape that is convex inward with respect to a virtual straight line (ridge line) connecting the distal end side portion and the proximal end side portion in the cross section including the central axis of the electrode 20. The outer diameter of the electrode 20 increases toward the base end side with respect to the axial direction of the electrode 20.
Angle A of the tapered portion in the electrode 20 is defined similarly to those according to the above embodiment, it is preferable that the angle A is between 0.2 ° ≦ A ≦ 8 °.

The tapered portion 27 of the electrode 20 shown in FIG. 5 has a shape that protrudes outward with respect to a virtual straight line (ridge line) connecting the distal end side portion and the proximal end side portion in the cross section including the central axis of the electrode 20. The outer diameter of the electrode 20 increases toward the base end side with respect to the axial direction of the electrode 20.
Angle A of the tapered portion in the electrode 20 is defined similarly to those according to the above embodiment, it is preferable that the angle A is between 0.2 ° ≦ A ≦ 8 °.

  Further, even if the entire electrode shaft portion of the electrode is configured to have a tapered shape whose outer diameter increases toward the base end side with respect to the axial direction, in the electrode shown in FIG. 1 and FIG. And the thing of the structure which does not have any one of a rear-end side part may be sufficient.

Furthermore, the electrode in the ultra-high pressure discharge lamp of the present invention does not need to be formed integrally with the electrode main body and the electrode shaft. For example, as shown in FIG. 36. By melting a portion located on the distal end side in a state where a wire rod made of tungsten is wound around the distal end of an electrode shaft portion 35 having a tapered portion 37 and a proximal end side portion 38 having an outer diameter D1 (> D2 ). When the tip of the electrode shaft portion 35 remains without being melted, the projection portion 33 where the discharge arc is concentrated at the time of lighting is formed, and the coil portion 32 is constituted by a part of the tungsten wire remaining without being melted. Thus, the electrode 30 in which the electrode main body 31 is formed may be used.

Furthermore, in the ultrahigh pressure discharge lamp of the present invention, other configurations are not limited to those of the above-described embodiment as long as the electrode has a tapered portion.
(1) As shown in FIG. 7, the coil member 29 is provided in the area | region which continues from the base end of the taper part 27 of the electrode 20 to the base end side part 28, and, thereby, the electrode shaft part 25 and an arc_tube | light_emitting_tube are directly connected. It may be a structure that does not come into contact with.
(2) In the ultrahigh pressure discharge lamp of the present invention, the sealing portion in the arc tube is not limited to the one formed by the shrink seal method, and may be formed by the pinch seal method.
(3) The present invention can be applied to both the AC lighting type and the DC lighting type. For example, in the DC lighting type, the desired effect can be obtained by configuring the cathode as having a tapered portion. Can be obtained.

It is sectional drawing which shows the outline of a structure in an example of the ultra-high pressure discharge lamp of this invention. FIG. 2 is an enlarged sectional view showing a part of the ultrahigh pressure discharge lamp shown in FIG. 1. It is sectional drawing which shows the expansion | swelling and contraction state of the electrode by lighting and extinguishing of the ultrahigh pressure discharge lamp shown in FIG. It is sectional drawing which shows schematically a part of structure in the other example of the ultrahigh pressure discharge lamp of this invention. It is sectional drawing which shows schematically a part of structure in the further another example of the ultrahigh pressure discharge lamp of this invention. It is sectional drawing which shows schematically a part of structure in the further another example of the ultrahigh pressure discharge lamp of this invention. It is sectional drawing which shows schematically a part of structure in the further another example of the ultrahigh pressure discharge lamp of this invention. It is sectional drawing which shows a part of structure in an example of the conventional ultrahigh pressure discharge lamp roughly. It is sectional drawing which shows schematically a part of structure in the other example of the conventional ultrahigh pressure discharge lamp.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Super high pressure discharge lamp 11 Light emission tube 12 Light emission part 13 Sealing part 15 External lead 18 Metal foil 20 Electrode 21 Electrode main body part 22 Coil part 25 Electrode axial part 26 Tip side part 27 Taper part 28 Base end part 29 Coil member 30 Electrode 31 Electrode body portion 32 Coil portion 33 Projection portion 35 Electrode shaft portion 36 Tip side portion 37 Tapered portion 38 Base end side portion 40 Electrode 41 Coil member 42 Light emitting tube 43 Sealing portion 45 Electrode 46 Tapered portion 48 Metal foil 50 Light emitting tube 51 Light emitting part 52 Sealing part

Claims (2)

A pair of electrodes facing each other and a light emitting part having a substantially spherical shape or a substantially elliptical spherical shape forming a discharge space in which 0.15 mg / mm ³ or more of mercury is enclosed, and both ends of the light emitting part Comprising an arc tube consisting of a rod-shaped sealing part continuously extending along the tube axis;
Each electrode has an electrode shaft portion extending along the tube axis, and a base end side portion of the electrode shaft portion is bonded to a metal foil embedded in an airtight manner so as to extend along the tube axis in the sealing portion. In the ultra high pressure discharge lamp
The electrode shaft portion of at least one of the electrodes has a larger outer diameter toward the outer side in the axial direction at the position of the minimum inner diameter portion that is the end portion on the sealing portion side of the inner surface of the light emitting portion forming the discharge space of the arc tube. An ultra-high pressure discharge lamp having a tapered portion. The tapered portion of the electrode shaft portion is formed so that the outer diameter is uniformly increased toward the outer side in the axial direction, and the angle A of the ridge line in the cross section including the central axis of the electrode with respect to the central axis of the electrode is The ultrahigh pressure discharge lamp according to claim 1, wherein the range is 0.2 ° ≦ A ≦ 8 °.

Images