JP2011060666A - Electrode for light source - Google Patents

Abstract

According to the present invention, it is a technical problem to realize a highly reliable light source electrode with high mechanical strength and low manufacturing cost.
In the light source device according to the present invention, a pair of large-diameter portions and a shaft portion are opposed to each other at the center portion of an arc tube made of a heat-resistant container, and a discharge substance and a starting gas are provided. A filled discharge vessel is formed, a pair of electrode sealing portions are formed from the discharge vessel to both ends of the arc tube, and are connected to the lighting circuit via electrode leads protruding from the end surfaces of the electrode sealing portion. In a light source device including a discharge lamp and a concave reflecting mirror (2) for collecting light emitted from the lamp, a heat dissipation member is attached to the electrode large diameter portion (20), and the large diameter portion and the A taper portion was provided between the shaft portions (21), and an arc transfer assisting member that easily concentrated an electric field on the electrode sealing portion side behind the center of the electrode large-diameter portion and easily raised the temperature was provided.
[Selection] Figure 2

Description

The present invention relates to a light source lamp electrode used in a liquid crystal projector, a DLP projector, and the like.

Light source devices for liquid crystal projectors and DLP projectors that are required to be small and have a bright projected image use a short arc type high-pressure mercury vapor discharge lamp that is compact and can produce high-intensity light emission. The light utilization efficiency tends to improve as the arc-to-arc distance decreases. However, as the arc-to-arc distance decreases, the light emitted from the arc is blocked by the electrodes and the efficiency is not improved. Therefore, the tip shape of the electrode is tapered so as not to block light, thereby improving the light use efficiency.

In the conventional light source electrode shown in FIG. 5, a tapered portion 45c is provided in a large-diameter discharge portion 45b, and the heat dissipating conductor 17 is disposed so as to surround the electrode shaft without integrally fusing the electrode shaft 45a behind the discharge portion. Thus, even when the distance between the arcs is shortened, the stability of the arc, the startability of the lamp, and the extension of the lamp life are achieved. (See Patent Document 1).

However, in recent years, there is a need for further short arcing, and the shape of the tip of the discharge part cannot be maintained only by heat conduction and heat dissipation of only the discharge part, resulting in a problem that the distance between arcs is increased and the arc becomes unstable. There was found.

In addition, the coil-shaped heat-dissipating conductor may change the electrode temperature distribution depending on its position, causing the arc to become unstable due to the deformation of the electrode, or it may disappear quickly because it does not shift from glow discharge to arc discharge at the start of the lamp. Furthermore, since the glow discharge time becomes longer, the amount of scattering of the electrode material due to ions generated by the glow discharge increases, resulting in a problem that the tube wall becomes black and the lamp has a short life. It is important that there is no movement due to positioning and temperature changes during the lifetime, and positioning and fixing are particularly difficult if the electrode shaft does not melt together.

The simplest method for attaching the heat dissipating conductor surrounding the electrode shaft is a method in which a coil-shaped heat dissipating conductor is prepared, and then press-fitted so as to abut against a vertical surface composed of the discharge portion and the electrode shaft, and is positioned and fixed.

However, since an abutting surface perpendicular to the electrode axis direction must be provided between the discharge part and the electrode axis, a taper part cannot be provided behind the discharge part when it is desired to easily position the discharge conductor.

When there is no taper part behind the discharge part, the mechanical strength against bending and bending decreases, and the difference in temperature distribution between the discharge part and the electrode shaft part becomes large. There was a problem that a crack occurred between the discharge part and the electrode shaft, the electrode was bent, and in some cases, the lamp was broken and the lamp became unsatisfactory. In addition, the coil loosened and moved due to thermal shock during the life.

In addition, when the discharge part and the electrode shaft are manufactured integrally, the simplest method is considered to be a method of cutting the electrode bar by attaching it to a lathe and cutting it. As the exit angle approaches 90 °, wear of the cutting blade becomes more severe and the frequency of replacement increases, resulting in an increase in production cost.

Japanese Patent No. 3623137

In the high pressure discharge lamp having a discharge lamp electrode composed of a large diameter portion and a shaft portion, the present invention ensures the stability of the arc at the time of lighting, and quickly shifts from the glow discharge to the arc discharge at the start of lighting, and is stable. Technical issues include ensuring startability, suppressing blackening in the arc tube due to scattering of the electrode material during glow discharge, extending the life of the lamp, and providing a simple configuration that does not increase production costs. Yes.

In order to solve the above-mentioned problems, a light source device according to claim 1 of the present invention is such that a discharge lamp electrode having a pair of large-diameter portions and a shaft portion manufactured by integral machining is opposed to the central portion of the arc tube. A discharge vessel filled with at least a luminescent substance and a starting gas is formed, and a pair of electrode sealing portions are formed from the discharge vessel to both ends of the arc tube, and projecting from the end surface of the electrode sealing portion. In a light source device comprising a high-pressure discharge lamp connected to a lighting circuit through the electrode lead and a concave reflecting mirror that collects light emitted from the lamp, a heat dissipation member is attached to the electrode large-diameter portion, In addition, a taper portion is provided between the large-diameter portion and the shaft portion, and an arc transition auxiliary member that easily concentrates an electric field on the electrode sealing portion side behind the center of the electrode large-diameter portion and easily raises the temperature is provided. And
A light source device according to a second aspect is the light source device according to the first aspect, wherein the arc transition member is a tungsten wire, and a method for producing the light source device is produced by fusing a coil-shaped heat radiation member disposed in a large diameter portion.

According to the present invention, it is possible to realize a stable electrode shape and a distance between arcs while maintaining an appropriate temperature distribution when a short arc high-pressure discharge lamp is turned on, and to make an arc transition that quickly shifts from glow discharge to arc discharge at the start of lighting. Because auxiliary members are provided, it is possible to suppress the scattering of electrode material due to the ions generated and accelerated by glow discharge at the start of lighting, which is the cause of blackening of the high-pressure discharge lamp. A highly reliable electrode for a light source can be realized.

The figure which shows an example of the light source device which concerns on this invention Electrode diagram for light source according to the present invention Explanatory drawing of the effect of the electrode for light sources which concerns on this invention The figure which shows another Example of the electrode for light sources which concerns on this invention Diagram showing conventional technology for improving light source life and arc stability

In the embodiment of the light source device according to the present invention, an electrode composed of a pair of large-diameter portions and a shaft portion is disposed opposite to a central portion of an arc tube made of a heat-resistant container, and filled with a discharge substance and a starting gas. A high-pressure discharge is formed, a pair of electrode sealing portions are formed from the discharge vessel to both ends of the arc tube, and connected to the lighting circuit via electrode leads protruding from the end surfaces of the electrode sealing portion. In a light source device including a lamp and a concave reflecting mirror that collects light emitted from the lamp, a heat dissipation member is attached to the electrode large-diameter portion, and a tapered portion is provided between the large-diameter portion and the shaft portion. And an arc transition assisting member that is easy to concentrate an electric field on the electrode sealing portion side behind the center of the electrode large-diameter portion and that easily raises the temperature.

The light source device according to the present invention shown in FIG. 1 includes a high-pressure discharge lamp 1 and a concave reflecting mirror 2 that reflects light emitted from the lamp 1, and the lamp 1 is an arc tube 3 made of quartz glass. A pair of tungsten electrodes 5R and 5L are arranged opposite to each other with a short inter-electrode distance of about 1 mm, and a starting gas such as mercury and bromine and an argon gas are enclosed in the discharge vessel 4. The portions from the discharge vessel 4 to both ends of the arc tube 3 are hermetically sealed to seal the electrodes 5R and 5L, the metal foil 6 made of molybdenum foil and the electrode lead 7 made of molybdenum wire connected thereto. A pair of attached electrode sealing portions 8R and 8L are formed. The electrode leads 9 protruding from the end faces of the electrode sealing portions 8R and 8L are connected to the one-pole side 10R and the other-pole side 10L of a lighting circuit (not shown) for supplying lamp power, respectively, A metal wire 11 serving as a trigger wire / antenna wire for promoting arc discharge between 5R and 5L has one end connected to the electrode lead 9 protruding from the end face 10 of the electrode sealing portion 9R, and the other end sealed with an electrode. It is wired so as to be wound around the outer periphery of the portion 8L in a loop shape.

The concave reflecting mirror 2 is formed with a bottom hole 12 at the bottom thereof, through which one electrode sealing portion 8L of the high pressure discharge lamp 1 is inserted and fixed with cement or the like, and at the reflection portion, the high pressure discharge lamp 1 A wiring hole 14 through which the lead wire 13 made of nickel wire connected to the electrode lead 8 projecting from the other electrode sealing portion 8R is inserted is drilled, and is pulled out from the wiring hole 14 to the back surface of the reflecting portion. A wiring fitting 15 for fixing the lead wire 13 is fixed.

As shown in FIG. 2, the tungsten electrodes 5R and 5L arranged in the discharge vessel 4 have a φ1.2 mm large diameter portion 20 having a tapered portion 26 having an angle of about 60 ° at the end and a φ0.4 mm shaft portion 21. The electrode large-diameter portion is manufactured by integral cutting, and a coil-shaped heat dissipation member 22 having a diameter of 0.25 mm is attached to the electrode large-diameter portion 20, and a tapered portion 23 is provided between the large-diameter portion 20 and the shaft portion 21. The arc transition assisting member 24 that easily concentrates the electric field and easily raises the temperature is provided on the electrode sealing portion side behind the center of 20.

The arc transfer auxiliary member 24 is a tungsten wire having a diameter of 0.25 mm and is wound behind the large-diameter portion 20 of the tungsten electrodes 5R and 5L including the large-diameter portion 20 and the shaft portion 21. After the heat dissipating member 22 that has been coiled is press-fitted into the large-diameter portion 20, the coil-shaped heat dissipating member 22 is applied by a laser or the like at a position 25 wound from the electrode sealing portion side of the coiled heat dissipating member 22 for one turn. It can be produced by fusing.

As a result, the arc transition auxiliary member 24, which is the member having the smallest heat capacity as the electrode constituent member in the discharge vessel 4, is produced, and the coil-shaped heat radiation member 22 is welded to the large diameter portion 20 and the position is fixed.

The heat dissipation member 22 is welded to the large-diameter portion 20 close to the arc at the highest temperature, thereby improving heat dissipation and thermal conductivity, maintaining a proper temperature distribution when the lamp 1 is lit, and realizing a stable electrode shape and distance between arcs. Moreover, further short arcing has become possible. In addition, by providing the taper portion 23, the temperature difference between the electrode tip and the vicinity of the sealing portion is alleviated, so that bending and bending during the lifetime do not occur, and the number of electrode breaks during electrode preparation and the number of blades to be cut are reduced. It was.

Further, before the start of lighting, as shown in FIG. 3, mercury 27 is liquefied in the vicinity of the electrode welded portion and in the vicinity of the electrode shaft portion 21. This is because the mercury 27 vaporized when the lamp 1 is turned on has the highest thermal conductivity when the lamp 1 is turned off, and the temperature near the electrode welded portion and the vicinity of the electrode shaft portion 21 that are relatively low in temperature is likely to be low.

When a high voltage is applied between the electrodes when the lamp 1 is lit, glow discharge is generated in the discharge vessel. At that time, the arc transition auxiliary member 24 causes local avalanche due to its heat capacity and shape, and arc discharge from glow discharge. To move quickly. Further, when the discharge is locally performed, the arc transfer auxiliary member 24 is in a state where the temperature is higher than that of the surrounding electrode constituent members due to the collision of ions and electrons, so the vicinity of the electrode welded portion and the vicinity of the electrode shaft portion 21. The mercury 27 that has been liquefied is vaporized.

This suppresses the collision of mercury 27 which vaporizes the scattering of the electrode material caused by the collision of the ions generated and accelerated by the glow discharge at the start of lighting, which is the cause of blackening due to an increase in the pressure in the tube. In addition, the colliding mercury 27 is ionized, the electrons in the tube increase, and it becomes easy to shift to arc discharge. Further, it is possible to realize a lamp electrode for a light source that can be easily manufactured at low cost and has high mechanical strength.

Next, another embodiment of the light source electrode according to the present invention is shown in FIG. 2 are the same members as the electrodes in FIG.

The arc transition assisting member 24a is a tungsten wire having a diameter of 0.25 mm, wound around the rear of the large-diameter portion 20 of the tungsten electrodes 5R and 5L including the large-diameter portion 20 and the shaft portion 21, and the manufacturing method thereof is coiled in advance. It is only necessary to press fit into the large diameter portion 20 and arrange it. The coil-shaped heat radiation member 22 is welded to the large-diameter portion 20 by a laser or the like at the winding end position 25a, and the edge portion at the winding end end of the coil-shaped heat radiation member 22 is formed into a fillet shape so that the electric field at the winding end end portion is obtained. Concentration is prevented and electric field concentration is urged only on the arc transition auxiliary member 24a.

As a result, the same effect as in the first embodiment can be obtained. The arc transition auxiliary member 24a is not limited to a coil shape, and may be any shape as long as the electric field concentrates and has a small heat capacity. For example, a metal foil or a plate shape may be used. Etc. are preferable.

The present invention contributes to long life and high efficiency of a high-pressure discharge lamp used in a light source device such as a liquid crystal projector or a DLP projector.

DESCRIPTION OF SYMBOLS 1 ... High pressure discharge lamp 2 ... Concave reflector 3 ... Arc tube 4 ... Discharge vessel 5R ... Electrode 5L ... Electrode 6 ... Metal foil 7 ... Electrode lead 8R ... Electrode Sealing part 8L ・ ・ Electrode sealing part 9 ・ ・ ・ External lead 10R ・ ・ One-pole side 10L of lighting circuit ・ ・ One-pole side 11 of lighting circuit ・ ・ ・ Metal wire 12 ・ ・ ・ Bottom hole 13 ・ ・ ・Lead wire 14 ... wiring hole 15 ... wiring fitting 20 ... large diameter portion 21 ... shaft portion 22 ... heat radiating member 23 ... taper portion 24 ... arc transition assisting member 24a ... Arc transfer auxiliary member 25 ... fusing position 26 ... taper part

Claims (2)

A discharge vessel filled with a discharge substance and a starter gas is formed at the center of an arc tube made of a heat-resistant vessel, and an electrode consisting of a pair of large diameter portions and a shaft portion is disposed opposite to the discharge vessel. A pair of electrode sealing portions are formed from both ends of the arc tube to the both ends of the arc tube, and a high-pressure discharge lamp connected to the lighting circuit via an electrode lead protruding from the end face of the electrode sealing portion, and light emitted from the lamp In the light source device including the concave reflecting mirror for collecting light, a heat radiating member is attached to the electrode large-diameter portion, and a tapered portion is provided between the large-diameter portion and the shaft portion, from the center of the electrode large-diameter portion. 1. A light source device comprising an arc transition auxiliary member which is easy to concentrate an electric field and to raise a temperature easily on the rear side of the electrode sealing portion. The light source device according to claim 1, wherein the arc transition member is a tungsten wire, and a method for producing the arc transition member is produced by fusing a coiled heat dissipating member disposed in a large diameter portion.

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