KR20120015262A - Discharge lamp - Google Patents

Abstract

PURPOSE: A discharge lamp is provided to suppress deformation of a discharge container due to heat originated from darkening, thereby preventing damage of the discharge container. CONSTITUTION: An anode(30) and a cathode are arranged within a discharge container by facing each other. A concavo-convex shape is arranged on the surface of the anode. A darkening suppression body is attached on the surface of the anode and includes alumina(26). The alumina is sprayed on the outer circumferential surface(30C) of the anode.

Description

Discharge Lamp

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge lamp in which electrodes are disposed in a light emitting tube, and more particularly, to a surface structure of an electrode used for a high brightness discharge lamp (HID lamp) such as a short arc type discharge lamp.

In a short arc type discharge lamp, a cathode and an anode are disposed opposite to a quartz glass discharge tube, and arc discharge is caused by electron emission from the cathode to the anode to discharge light. As the electrode material, high melting point tungsten (W) is generally used to prevent electrode dissolution during lighting.

In addition, in the case of a cathode used in a high-brightness discharge lamp, a tungsten cathode (common name) doped with thorium oxide (ThO ₂ ), which is an electron radioactive material (electron emitting material) having a relatively low operating temperature, in order to increase electron emission capability and emit light with high brightness. , Toritan cathode) is used (see Patent Documents 1 and 2, for example).

During arc discharge, the temperature of the negative electrode tip and the positive electrode tip increases by electron emission. When the temperature rises to near the melting point of the electrode material, the negative electrode tip and the positive electrode tip dissolve and evaporate, and the electrode is consumed. The evaporated metal adheres to the inner wall of the discharge tube, whereby the inner wall of the light emitting tube is blackened. In other words, the adhesion of metal causes a decrease in transmittance and the light output of the lamp is reduced. In addition, when the inner wall of the light emitting tube is blackened, the blackened portion may become locally high temperature, whereby deformation due to heat is accumulated in the light emitting tube, and the lamp may rupture.

In the case of a toritan cathode, thorium forms a monoatomic layer on the surface of the electrode by a reducing action, but oxygen separated from the thorium on the surface combines with tungsten at the tip of the anode, which lowers the melting point of the tip of the cathode, thereby consuming the electrode. . In order to prevent such electrode consumption, for example, a toritan cathode is formed, and a layer (talorium layer) containing no thorium oxide is formed near the cathode surface by vacuum heating treatment (see Patent Document 3).

Alternatively, blackening of the light emitting tube can be prevented by coating alumina (Al ₂ O ₃ ), which is a transparent polycrystal, on the inner surface of the light emitting tube (see Patent Documents 4 and 5). Alumina is more chemically and physically stable than quartz glass of the discharge tube material, and does not react with charged particles, compounds, etc., such as metals and ions emitted from the electrode during lighting, and prevents blackening of the light emitting tube.

[Patent Document 1] Japanese Unexamined Patent Publication No. 579044

[Patent Document 2] Japanese Unexamined Patent Publication No. 200322780

[Patent Document 3] Japanese Unexamined Patent Publication No. 2003257365

[Patent Document 4] Japanese Unexamined Patent Publication No. 61294752

[Patent Document 5] Japanese Patent Application Laid-Open No. 2002157974

In the process of forming a special metal layer near the cathode surface, such as a thallium layer, the work process is complicated, which lowers the lamp production efficiency. If an appropriate thorium layer is not formed on the surface of the cathode during arc discharge, blackening of the discharge tube or a decrease in brightness is caused. For example, if there is too much thorium to recrystallize on the surface of the cathode to emit electrons, the electrode temperature may be reduced. The thorium evaporates by the rise and adheres to the discharge tube. Conversely, if the thorium is too small, the electron emission capability of the cathode does not rise.

On the other hand, the process of coating alumina or the like on the inner surface of the discharge tube is also a complicated work process, which deteriorates the production efficiency. Moreover, even if it coats, the heat-discharged discharge tube itself contains heat, and due to the influence of heat, it cannot have sufficient coating performance, and the transmittance | permeability falls.

The discharge lamp of the present invention is a discharge lamp that does not require complicated work steps and can prevent blackening of the discharge container, and has a discharge container and a positive electrode and a negative electrode disposed opposite to the discharge container. For example, discharge lamps, such as a short arc type discharge lamp, which output light of high brightness in the state of high temperature, are comprised. However, you may apply to electrodes of discharge lamps other than a short arc type discharge lamp. The discharge vessel may be made of quartz glass or the like that transmits light, and the electrode may be made of metal material such as tungsten. Moreover, potassium may be included as an anode.

In the present invention, at least a minute groove is formed on the surface of the anode. For example, it is possible to form a fine groove by applying a surface treatment. Here, the minute trench means a roughly rough state without a gloss and refers to a trench of several tens of micrometers. As surface treatment, it is possible to perform surface finishing by blasting processes, such as a shot blast, a wet blast, and a sand blast. Or a fine groove (a groove of several hundred micrometers) is formed by methods other than surface treatment, such as mechanical finishing, laser processing, and electrical discharge machining. In other words, it is possible to roughen the surface. The blackening inhibitor can enter into such a minute groove, and it becomes easy to adhere to the surface of an anode.

In the present invention, preventing blackening of the discharge vessel (hereinafter referred to as blackening suppressor) is interspersed and adhered to the formed anode surface of the micro-ditch. Here, the "blackening inhibitor" is a granular material which does not react with the composition material (for example, quartz glass) of the discharge vessel (without blackening phenomenon) and which does not reduce the transmittance of light as much as possible even when attached to the inner surface of the discharge vessel. It shows that it is a substance and a composition. In addition, "scattering" means that the surface is scattered sparsely (in a uniformly dispersed state), and is different from, for example, a state in which blackening inhibitors cover the anode surface to every corner. The blackening inhibitor is constituted by, for example, aggregates of minute agglomerates such as granules and powders, and the size thereof is not limited. The degree (size) of the fine grooves on the surface of the anode can also be determined depending on the size of the blackening inhibitor.

When the anode temperature rises due to the arc discharge, the blackening inhibitor adhering to the anode surface dissolves and evaporates. Since the surface of the anode is in a rough state, the blackening inhibitor is likely to evaporate. The blackening inhibitor evaporated by the tropical flow which generate | occur | produced in a discharge container contacts with the inner surface of a discharge container, and becomes solid and adheres. Since the blackening inhibitor is scattered on the surface of the anode, it evaporates randomly from the surface of the anode and adheres to the discharge vessel by tropical flow. Thus, in this invention, the protection process like coating is performed with lighting time lapse with respect to the inner surface of a discharge container by the lighting operation after lamp manufacture.

Metals used as electrode materials, such as tungsten and thorium, dissolve and evaporate when the electrode is heated and adhere to the discharge vessel, causing blackening of the inner surface of the discharge vessel. In particular, in the case of a short arc type discharge lamp, since the cathode and anode tip portions become high temperature around 2000 ° C., the electrode metal is likely to evaporate.

However, in the present invention, when the lamp is started after the lamp is manufactured, the blackening inhibitor adhering to the anode surface in advance evaporates and adheres to the discharge vessel. The blackening inhibitor adhering to the inner surface of the discharge vessel does not react with the discharge vessel and does not lower the transmittance of light, and therefore does not blacken the discharge vessel.

On the other hand, when the blackening inhibitor adheres to the inner surface of the discharge vessel, the metal of the electrode material evaporating from the electrode such as tungsten or the metal enclosed in the discharge tube for emitting light such as mercury does not react with the glass. That is, the metal which causes blackening prevents adhesion to a discharge container. As a result, even if the lamp is used for a long time, blackening does not proceed, and the lamp can be continuously lit with stable illumination.

It is preferable to surface-treat as a method of fixing to a positive electrode surface reliably, without peeling a blackening suppressor from a lamp manufacturing process to a lighting start. In order to roughen the surface of the anode by surface treatment, the blackening inhibitor is strongly adhered to the surface of the anode, and the blackening inhibitor does not peel off from the surface of the anode during the lamp manufacturing process such as electrode heating treatment, and blackening until the lamp is turned on for the first time after manufacture. This allows the inhibitor to be strongly fixed against the anode surface.

In particular, as a simple and easy method for reliably attaching the blackening inhibitor, it is good to apply a blast treatment to make the blackening inhibitor collide with the surface of the anode. The blackening inhibitor is extruded on the surface of the anode by high compression so that an uneven state (a matte, rough state and easy state) is formed on the surface of the anode, while a part of the collided blackening inhibitor depresses the surface of the anode. Crash while being fixed. In order to perform a blasting process, a blackening inhibitor adheres to the surface of an anode in the state scattered.

In addition, by attaching the blackening inhibitor to the concave formed recess on the surface of the anode, the blackening inhibitor is prevented from protruding from the surface of the anode, so that the blackening inhibitor is not peeled off even if a flow occurs in the light emitting tube during the vacuum exhaust treatment of the lamp manufacturing process. Do not.

When electrode metals, such as tungsten, evaporate, the metal which evaporated floats in the discharge container. In order to vaporize the blackening inhibitor as soon as possible from the start of the lighting, and to attach it to the inner surface of the discharge vessel, it is preferable to use the blackening inhibitor which evaporates before the metal which is the electrode material of the anode.

In addition, when mercury is enclosed in a discharge vessel, a discharge vessel such as quartz reacts with mercury or mercury oxide. When mercury enters the discharge vessel, the amount of mercury contributing to light emission decreases, and the illuminance decreases. In order to prevent this, it is preferable that a blackening inhibitor is a blackening inhibitor which does not produce a chemical reaction with a metal or a metal compound with respect to the composition material (quartz glass etc.) of a discharge container.

As the blackening inhibitor, a metal blackening inhibitor or a metal compound blackening inhibitor such as a metal oxide may be used. For example, it is preferable to use alumina (aluminum oxide) which does not react with quartz glass. Alumina is a physically and chemically stable polycrystal, for example, transparent alumina is used.

In order to dissolve and evaporate the blackening inhibitor as soon as possible after the start of the lamp, a region in which the blackening inhibitor is dissolved and evaporated most efficiently can be determined for the anode surface region to which the blackening inhibitor is attached.

On the other hand, when the discharge lamp is provided in a form in which the electrode is placed in the vertical direction with the anode upward, the temperature distribution on the surface of the anode has an unusual distribution. That is, the positive electrode tip portion becomes very hot due to the electron emission from the negative electrode, and the temperature is lower at the positive electrode end surface on the electrode support rod side than the electrode tip portion close to the negative electrode side. Further, convection occurs in the discharge tube along the anode outer peripheral surface (side surface).

Therefore, it becomes possible to attach a blackening inhibitor along the outer peripheral surface (side surface) of a positive electrode, to melt | dissolve a blackening inhibitor quickly, and to make it adhere to the inner surface of a discharge tube. It is also possible to attach partially along the circumferential direction, and may attach a blackening suppressor over the whole main direction. For example, when the anode is formed from a tapered tip and a circumferential body portion, the blackening inhibitor may be attached to the outer circumferential surface of the body portion. In particular, by analyzing the anode temperature distribution during lighting, the blackening inhibitor may be concentrated in the region along the electrode axial direction where the blackening inhibitor is most likely to evaporate.

In order to reliably adhere the alumina to the surface of the anode, it is preferable to form a fine groove (for example, a groove in micrometers) where the blackening inhibitor is sandwiched (for example, along the main direction). As the blackening inhibitor is inserted in such a fine groove, it becomes easy to adhere to the surface of the anode. Moreover, when blackening inhibitor suppresses evaporation, a fine groove functions as a heat dissipation structure. For example, it is preferable to form a fine groove in the optimal region from the temperature distribution of the anode.

In order to increase the deposition amount of the blackening inhibitor, it is preferable to form a groove (corrugated corrugated tube) in a cross section along the circumferential direction on the outer circumferential surface of the anode. This groove is a groove much larger than the fine groove (for example, in mm units), and an inclined surface is formed on the surface of the anode. As a result, more blackening inhibitor can be stuck by surface treatment etc. For example, in consideration of the temperature distribution, a groove having a cross-sectional waveform may be formed in the most suitable region.

When fine unevenness | corrugation is formed in the surface of an anode, peeling of a convex part occurs easily in a lamp manufacturing process, and foreign substances, such as dust, are easy to adhere to the surface of an anode. In order to prevent this, it is preferable to provide an anode with a shaft diameter portion having an outer diameter smaller than that of the anode, and attach the blackening inhibitor to the surface of the shaft diameter portion. It is also effective when fine trenches and cross-sectional corrugated trenches are formed on the anode surface, especially on the outer circumferential surface.

On the other hand, in order to quickly attach the vaporized blackening inhibitor to a region where blackening of the inner surface of the discharge tube is likely to occur by convection in the discharge tube, it is preferable to form a convex portion on the rear end surface of the electrode supporting rod side of the anode. Since the airflow that falls along the electrode support rod from the vertical upper portion to the lower portion (cathode side) collides with the convex portion, an upward airflow occurs, and the rise of the airflow along the outer circumferential surface (side) of the anode causes the blackening inhibitor to become blackened on the inner surface of the discharge tube. We can move to area that is easy to occur. Therefore, deformation due to heat of the discharge vessel due to blackening can be suppressed. For example, a relatively large trench is formed along the circumferential direction.

In the method of manufacturing the discharge lamp of the present invention, the blackening inhibitor is projected onto the surface of the anode by blasting, the blackening inhibitor is scattered on the surface of the anode, and impurities are removed at a temperature below the melting point of the blackening inhibitor. A heat treatment for removal is performed on the anode.

According to this invention, blackening of a discharge container can be prevented, without involving a complicated work process. In addition, accumulation of deformation due to heat of the discharge vessel due to blackening can be suppressed, and damage to the discharge vessel can be prevented.

1 is a schematic cross-sectional view of a short arc type discharge lamp as a first embodiment.
2 is an enlarged plan view of the side surface of the anode.
3 is an enlarged cross-sectional view of the surface of the anode as a second embodiment.
4 is a plan view of the anode as a third embodiment.
5 is a plan view of the anode as a fourth embodiment.
6 is a cross-sectional view of the anode as a fifth embodiment.
7A and 7B are enlarged photographs of electron microscopes on the side of the anode before and after blasting.
8 is an enlarged view of an electron microscope showing the surface of the anode of the discharge lamp of the present embodiment from above.
9 is an enlarged photograph of an electron microscope seen from an oblique direction of an anode surface.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described with reference to drawings.

1 is a schematic cross-sectional view of a short arc type discharge lamp as a first embodiment.

The short arc type discharge lamp 10 includes a light emitting tube 12 made of transparent quartz glass. In the light emitting tube 12, the cathode 20 and the anode 30 are disposed to face each other at a predetermined interval. On both sides of the light emitting tube 12, encapsulating tubes 13A and 13B made of quartz glass are connected to the light emitting tube 12 and integrally formed. In the discharge space S in the light emitting tube 12, rare gases such as mercury and argon gas are sealed.

Inside the sealing tubes 13A and 13B, conductive electrode supporting rods 17A and 17B supporting the cathode 20 and the anode 30 are disposed. The electrode supporting rods 17A and 17B are connected to the conductive lead rods 15A and 15B through the metal foils 16A and 16B, respectively. Both ends of the sealing tubes 13A and 13B are blocked by the clasps 19A and 19B, and at the same time, a glass tube (not shown), a glass rod (not shown), and welding (溶 着) provided therein are provided. In this way, the light emitting tube 12 is closed.

The lead rods 15A and 15B are connected to an external power supply unit (not shown), so that electric power is supplied to the cathode 20 and the anode 30 via the lead rods 15A and 15B. When a voltage is applied between the cathode 20 and the anode 30, arc discharge occurs between the electrodes of the cathode 20 and the anode 30, and light is emitted toward the outside of the light emitting tube 12. Here, the anode 30 and the cathode 20 are arranged in the discharge lamp 10 in a line along the vertical direction.

2 is an enlarged plan view of the anode seen from the side surface.

The anode 30 is an electrode containing 0.002 percent of potassium in the tungsten electrode, and has a cylindrical body portion 30B connected to the electrode support rod 17B and a tapered shape from the body portion 30B toward the cathode 20. It is comprised by the tip part 30A. During lamp lighting, electrons are emitted from the tip of the cathode, and an arc discharge is generated between the cathode 20 and the anode 30.

Alumina 26 (Al ₂ O ₃ ), which is a transparent polycrystalline body, is scattered and adhered to the outer peripheral surface (side surface) 30C of the body portion 30B having a constant outer diameter. The attachment region R has a predetermined width along the electrode axis X direction and is defined as an area over the entire main direction. In addition, although the width | variety of the adhesion | attachment area | region R can be determined in consideration of the anode surface temperature distribution along the electrode axis X during lighting, it is good to include the anode surface of the tip side which becomes high temperature at least.

The alumina 26 is a physically and chemically stable crystal and does not react with the light emitting tube 12 of quartz glass. Alumina 26 is deposited by surface treatment on the anode 30. In this embodiment, a blasting process, specifically shot blasting which injects alumina to the anode 30 at high pressure as surface treatment, is performed. When shot blasting, the alumina powder which is the particle size 105-125 of a predetermined range is sprayed at high pressure toward the attachment area | region R of the outer peripheral surface 30C.

The adhesion region R of the outer circumferential surface 30C of the anode 30 is formed in a rough state (easy state) and irregularities as a result of alumina being injected. In other words, it becomes a rough surface with minute irregularities. In addition, a part of the alumina that has collided with the outer circumferential surface 30C is clamped to the outer circumferential surface 30C while being inserted into the outer circumferential surface 30C in a recessed state (penetrating) and allowing the outer circumferential surface 30C to enter by the collision itself. do.

In addition, during shot blasting, the alumina powder is uniformly sprayed toward the outer circumferential surface 30C. For this reason, alumina to adhere is dispersed throughout the outer circumferential surface 30C and scattered sparsely. The injection apparatus (not shown) which performs surface treatment sets injection pressure so that alumina may adhere as it is after it collides with the outer peripheral surface 30C.

When blasting is performed, the anode 30 is heated in a vacuum atmosphere. The heat treatment is performed at a temperature lower than the melting point of the alumina to prevent evaporation of the alumina. For example, the anode 30 is heated at about 1600 ° C. for several tens of minutes. As a result, the alumina adhered to the anode 30 becomes intimate and fixed to the outer circumferential surface 30C, and impurities contained in the electrode are removed in the process during electrode assembly.

When the lamp is turned on and started after lamp production, the temperature of the anode 30 reaches the melting point of the alumina to about 2000 ° C. As a result, the alumina 26 dissolves and evaporates. The alumina 26 evaporates one by one with the elapse of the lighting time, and finally, most of the alumina adhering to the anode 30 is separated from the anode 30. The evaporated alumina adheres to a predetermined region of the inner surface of the light emitting tube 12 by tropical flow in the light emitting tube 12. This area | region is made into the area | region where metal etc. are comparatively easy to attach by tropical flow.

The alumina adhered over the entire inner surface of the light emitting tube 12 functions as a coating film. That is, tungsten, thorium, evaporated and suspended in the light emitting tube 12, mercury oxide produced by discharge light emission, other impurities, etc. do not adhere to the alumina region attached to the inner surface of the light emitting tube 12, It will stick to an area that is not attached to it or will continue to float.

Thus, according to this embodiment, alumina is sprayed on the outer peripheral surface 30C of the anode 30 by shot blasting, and the alumina 26 is attached to the side surface 30C in a scattered state. Then, the anode 30 is vacuum heated to below the melting point of the alumina 26 to remove impurities. When the lamp is turned on and started, the alumina 26 dissolves and evaporates with the temperature rise of the anode 30. The evaporated alumina adheres to the inner surface of the light emitting tube 12.

Tungsten has a very high melting point, but when the cathode and anode tips are very heated, tungsten will evaporate. In addition, mercury encapsulated in the light emitting tube reacts with oxygen to produce mercury oxide, which adheres to the inner surface of the light emitting tube. The attachment of such mercury oxide and tungsten leads to blackening of the light emitting tube.

On the other hand, alumina is a transparent polycrystalline body, and is stable without causing reaction with tungsten, mercury or impurity gas, charged particles, etc. generated during light emission, compared to quartz glass, which is a material of the light emitting tube 12.

In the present embodiment, after the lamp is manufactured, the lamp is turned on and started a short time before the alumina evaporates and adheres to the light emitting tube 12. The deposition of alumina is faster than the evaporation of tungsten and occurs almost simultaneously with the evaporation of thorium evaporating from the cathode tip. As a result, the alumina 26 adhering to the anode side surface 30C first moves on the inner surface of the light emitting tube 12 so as to prevent blackening.

Therefore, even if tungsten and mercury oxide are suspended in the light emitting tube 12, they do not adhere to the light emitting tube 12, but the tungsten and mercury oxide adheres to the inner surface of the light emitting tube so that the light emitting tube is blackened (transmittance decreases). Can be. In addition, since tropical currents are generated in the light emitting tube 12, the evaporated alumina attaches mainly to an area where blackening of the inner surface of the light emitting tube 12 is likely to occur, thereby preventing the light emitting tube 12 from blackening. do.

Since the protection function by this coating is realized without coating in the lamp manufacturing process, it is unnecessary to perform complicated work in the lamp manufacturing process. Moreover, since blasting is performed as the surface finish of the electrode surface, it is possible to attach alumina by this, and there is no need to provide a process for attaching alumina separately.

The alumina 26 can be firmly attached to the surface of the anode because the alumina is stuck to the surface and formed in the recessed or recessed state in the state where the surface of the anode is roughened and irregularities are formed. Therefore, peeling can be prevented during the manufacturing process before starting such as a ramp point. In addition, alumina is attached and fixed to the surface of the anode after the anode is integrally molded. That is, compared with the case where it mixes in the inside of an anode, since alumina does not form the strong binder with respect to the surface of an anode, when an electrode temperature rises to near an alumina melting point, alumina can easily evaporate from the surface of an anode.

During lighting of the discharge lamp, the anode is disposed above the cathode, and upward flow occurs along the anode side due to tropical flow in the discharge space. In this embodiment, since alumina adheres to the anode side surface, the alumina evaporates early and moves quickly in the discharge space by convection toward the electrode shaft, and adheres to the light emitting tube. In addition, since the adhesion region R of alumina is determined based on the anode temperature distribution during lighting, it becomes possible to evaporate alumina reliably.

In this embodiment, although alumina was affixed on the side of the anode which is easily moved by convection in the discharge space, alumina may be attached to the other surface portion of the anode. Moreover, you may spray powder other than alumina, and particle | grains (stereoscopic body) with respect to an anode. Particles to be sprayed are transparent crystals which do not lower the transmittance of the light emitting tube, and do not cause chemical reactions with light emitting tube materials such as quartz glass or materials and compounds that convex in the light emitting tube such as tungsten, mercury and discharge gas. And physically and chemically stable particle bodies (metal grains, metal oxides, etc.).

The blasting treatment may be any method such as sand blast, wet blasting (liquid honing), shot blasting, or the like. Moreover, you may comprise so that an anode may be surface-treated by methods other than a blast, and alumina is made to adhere. In addition, the particle body may be scattered and adhered to the surface of the anode in accordance with a method other than surface treatment (for example, by strongly pushing the particle body into the inside of the surface of the anode).

Next, the discharge lamp which is 2nd Embodiment is demonstrated using FIG. In the second embodiment, fine trenches are formed along the circumferential direction of the anode surface. About the other than that structure, it is substantially the same as 1st Embodiment.

3 is an enlarged cross-sectional view of the surface of the anode in the second embodiment.

On the surface 130C of the anode 130, a small pitch trench 13ON (herein referred to as a micro trench) is formed along the main direction by laser processing, braid processing, electrical discharge machining, etc. It is formed to have a predetermined width.

The concave portion 130G of the fine trench 13ON is formed in a wedge shape (acute angle state) so that the pitch J with an order of micrometer (μm) is ordered so that the alumina fits the concave portion 130G during the blasting process. Ditch is formed. The anode surface area | region formed in the fine groove 130N is a part or whole area | region of the adhesion | attachment area | region R demonstrated in 1st Embodiment, and is determined as the area | region where alumina is easy to evaporate especially during lighting.

The pitch J of the fine trench 13ON is relatively large in order to prevent the convex portion 130T on the surface alternately showing the fine trench 13ON from being peeled off and inserted into its recess 130G.

That is, the width of the convex portion 130T is sufficiently larger than the width of the concave portion 130G.

By forming such a fine groove, the alumina can be adhered to the surface more reliably by sand blasting treatment, so as to be in close contact even when the lamp is manufactured. In addition, based on the temperature distribution along the electrode axis direction, since the fine trench 130 is formed in the region where alumina evaporation can be most effectively realized, alumina evaporation is assured. In addition, after the alumina evaporates, the fine groove 130 can fulfill the function of the heat radiation fins, thereby preventing overheating of the electrode.

In addition, you may make alumina adhere to a fine groove by methods other than a blast process. For example, it is also possible to adhere alumina by pressing firmly on the surface of the anode. In addition, the alumina adhesion region may be concentrated in a specific region.

Next, the discharge lamp which is 3rd Embodiment is demonstrated using FIG. In the third embodiment, a trench having a corrugated gate shape (cross section) is formed on the surface of the anode. About another structure, it is the same as that of 1st Embodiment.

4 is a plan view of the anode in the third embodiment.

On the outer circumferential surface 230C of the anode 230, a colgate groove 230W is formed in the region W which is a part of the attachment region R of the alumina. The corrugated trench 230W is a trench that forms a series of top cross-sectional waveforms along the electrode axial direction, and a recess is formed that is sufficiently larger than the alumina particles (visually visible). Here, it forms in the order of millimeters (mm) according to the circumferential direction of the outer peripheral surface 230C of the groove 230W by cutting processing etc. here.

The colgate groove 230W is formed along the main direction, and the area of the anode surface is enlarged. Therefore, while the adhesion amount of alumina increases, attachment of alumina becomes easy in sandblasting in a diagonal direction.

In addition, like the second embodiment, the alumina may be attached to the fine trench by a method other than the blast treatment. In addition, the fine trench described in the second embodiment may be further formed on the colgate trench.

Next, the discharge lamp which is 4th Embodiment is demonstrated using FIG. In the fourth embodiment, a narrow diameter portion having a small outer diameter is formed on the surface of the anode. About the other than that structure, it is substantially the same as 3rd embodiment.

5 is a plan view of the anode in the fourth embodiment. In the anode 330, a narrow diameter portion 330B having a smaller outer diameter than the end portion 33OA near the electrode support rod is formed at a width Z interval. Alumina is attached to the partial region R of the anode surface 330C by sand blasting. In addition, a colgate groove 330W is formed in the circumferential direction over the region W. As shown in FIG.

By forming such a thin portion on the anode, it is possible to prevent the alumina attached at the time of lamp manufacture from peeling off. In addition, alumina is prevented from adhering to the surface of the positive electrode together with foreign matter such as fine dust. In addition, the fine convex portions formed on the surface or the convex portions of the fine grooves can be prevented from being peeled off by sand blasting, or they can be prevented from being integrally attached to the foreign matter.

In addition, you may make alumina adhere with methods other than surface treatment, such as sandblasting. Moreover, it is not necessary to form a colgate groove, and it is not necessary to form a fine groove.

Next, the discharge lamp which is 5th Embodiment is demonstrated using FIG. In 5th Embodiment, the recessed part is formed in the electrode back side. About the other than that structure, it is substantially the same as 3rd embodiment.

6 is a cross-sectional view of the anode in the fifth embodiment. In the end surface of the electrode support rod side of the anode 430, the groove 430M is formed to draw a circle along the main direction. Alumina is attached over the region R, and a colgate groove 430W is formed in the circumferential direction over the region W. As shown in FIG.

By providing the recessed portion to be such a pit on the anode end surface side, the downdraft generated during lamp lighting collides with the electrode and flows upward with the updraft. The alumina which rises with the rising air moves quickly to a part which is easy to adhere in a discharge tube, and concentrates the area | region which alumina adheres previously, and can improve a coating effect.

Hereinafter, the Example of a discharge lamp is described.

Example 1

The discharge lamp of the present example corresponds to the discharge lamp described in the first embodiment.

7 is an enlarged photograph of an electron microscope of the side of the anode before blasting and after blasting. As shown in Fig. 7A, before the blast treatment, the anode side is almost smooth. On the other hand, the anode side after the blister process is in a glossless rough state (easy state), and becomes a fine uneven | corrugated shape. In the enlarged photograph of FIG. 7B, the portion where the alumina collides with the anode side and is fixed in the cut state together with the portion inserted in the sharp shape of the alumina and the portion where the electrode fragments are attached.

[Example 2]

This example corresponds to the discharge lamp in the second embodiment.

8 is an enlarged electron microscope photograph of the anode surface of the discharge lamp of the present embodiment from above. 9 is an enlarged photograph of an electron microscope seen from an oblique direction of an anode surface.

As clearly shown in Figs. 8 and 9, on the anode surface, fine trenches having a trench pitch greater than the trench width are formed along the main direction. And it turns out that a large amount of alumina is inserted in the fine groove part properly, and adheres.

Example 3

The discharge lamp of the present example corresponds to the discharge lamp described in the fifth embodiment.

An experiment was conducted to confirm the effect of suppressing blackening of the light emitting tube when alumina was attached to the surface of the anode. The short arc type discharge lamp of the Example is equipped with the light emitting tube completed from outer diameter 121mm, volume 885cc, and quartz glass. About 30 mg / cc of mercury was enclosed in the light emission tube.

Moreover, argon gas was enclosed so that it might be about 190 kPa at normal temperature.

The positive electrode is a tungsten electrode containing potassium in a weight ratio of about 0.002%. The cathode is a tungsten electrode doped with thorium oxide (ThO ₂ ) having a weight ratio of about 2%, and the distance between the electrodes is set to about 12 mm. The shape of the positive electrode and the negative electrode is almost the same as the shape shown in the above embodiment. A thin tapered tip is formed on the cathode.

For the call side gate-shaped ditch is formed in the positive electrode, carry out the blast treatment for spraying of alumina (Al ₂ O _3), said surface treatment on the positive side. An alumina powder having a particle size of about 115 was used to impinge the alumina powder into a predetermined region on the side of the anode by the injection pressure of the pressurized gas, to complete the surface, and to attach the alumina.

On the other hand, a short arc discharge lamp having the same structure as in the present example was prepared except that alumina was adhered as a comparative example.

And the confirmation experiment of alumina evaporation was performed. Here, the anode was subjected to heat treatment in a vacuum environment, to actually create an electrode temperature environment (1500 ° C. or more) at the time of lamp lighting, and to investigate the residual amount of alumina at an electrode temperature lower than the alumina melting point and a high electrode temperature.

Alumina remained when the electrode was heated to 1500 ° C., but when heated to 2200 ° C., alumina did not remain.

Next, a confirmation experiment was performed to prevent blackening by attaching alumina to the surface of the anode. Here, the short arc-type discharge lamp of the said Example was made to light with the electric power of 12 kW, and the blackening state of the light emitting inner surface after 1000 hours of lighting was examined.

The illuminance retention was measured by an illuminometer having sensitivity at around 350 nm. Although the roughness retention rate of the conventional lamp without alumina adhesion by sand blasting process was 67%, while the colgate groove was not formed, the illuminance retention rate of this lamp as an example was 75%, and it was confirmed that blackening of the light emitting tube was suppressed. It became.

10 short arc type discharge lamp
12 Light-emitting tube (discharge container)
20 cathode
26 alumina
30 anodes

Claims (16)

With discharge vessel,
An anode and a cathode disposed opposite to the discharge vessel,
At least minute irregularities are formed on the surface of the anode,
The blackening inhibitor is scattered on the surface of the anode, and adheres to the discharge lamp, wherein the discharge lamp evaporates at the time of lighting. The method of claim 1,
And said blackening inhibitor evaporates before metal which is an electrode material of said anode. The method according to claim 1 or 2,
A discharge lamp, characterized in that the blackening inhibitor does not cause a chemical reaction with a metal or metal compound suspended in the discharge vessel when lit, compared with the composition material of the discharge vessel. The method according to claim 1 or 2,
The discharge lamp, characterized in that the blackening inhibitor is a metal particle body or a metal compound particle. The method according to claim 1 or 2,
And said blackening inhibitor comprises alumina. The method according to claim 1 or 2,
The blackening suppressor adheres to the concave portion of the surface of the anode. The method according to claim 1 or 2,
The positive electrode is surface-treated by the blasting process which makes the blackening inhibitor collide with the said anode surface, and the blackening suppressor is crash-fixing, while recessing the said anode surface, The discharge lamp characterized by the above-mentioned. The method according to claim 1 or 2,
A discharge lamp, wherein said blackening inhibitor is attached to said anode outer circumferential surface. The method according to claim 1 or 2,
The anode consists of a tapered tip and a cylindrical body portion,
The blackening suppressor is attached to the outer peripheral surface of the said body part, The discharge lamp characterized by the above-mentioned. The method according to claim 1 or 2,
A fine groove is formed on an outer circumferential surface of the anode, and the blackening suppressor can be fitted into the fine groove. The method of claim 10,
The ditch gap of the said fine groove is more than the magnitude | size of the said blackening inhibitor. The method according to claim 1 or 2,
A discharge lamp, characterized in that a groove having a corrugated cross section is formed on an outer circumferential surface of the anode. The method according to claim 1 or 2,
The anode has a shaft diameter portion of the outer diameter smaller than the anode outer diameter,
The blackening suppressor adheres to the surface of the shaft diameter portion. The method according to claim 1 or 2,
Discharge lamp, characterized in that the anode comprises potassium. The method according to claim 1 or 2,
A discharge lamp, characterized in that the recessed portion is formed in the rear end surface of the electrode support rod side of the anode. The blackening inhibitor is projected on the surface of the anode by blasting, the blackening inhibitor is scattered on the surface of the anode, and a heat treatment for removing impurities at a temperature below the melting point of the blackening inhibitor is performed on the anode. The manufacturing method of the discharge lamp characterized by the above-mentioned.

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