Short arc discharge lamp

Abstract

A lamp structure is provided that can avoid the occurrence of blackening of the arc tube due to evaporation of a coil as a starting member without deteriorating the starting performance of a short arc discharge lamp having a pair of electrodes disposed opposite to each other in the arc tube. The structure is characterized in that the electrode is composed of an electrode core wire and a large-diameter electrode main body formed at the front end of the electrode core wire, and a single-layer ring-shaped member is provided so as to surround the periphery of the electrode main body.

Description

Technical Field

[0001] The present invention relates to a short arc discharge lamp for a projection type projector device, a projector, etc., and more particularly to a short arc discharge lamp having an electrode provided with a member for starting. Background Art

[0002] Currently, as a short arc discharge lamp for the above-mentioned purpose, a short arc discharge lamp having a rare gas such as mercury or xenon sealed in a light emitting tube is used.

[0003] Its structure is as Figure 5 As shown, the short arc discharge lamp 1 includes a pair of electrodes 3, 3 disposed opposite to each other in a light emitting tube 2. Halogen is sealed in the light emitting tube 2 in addition to mercury and rare gas, and blackening in the light emitting tube 1 is suppressed by a so-called halogen cycle.

[0004] In addition, in such short arc type discharge lamps, there is a known structure in which a coil is wound around an electrode as a starting member for improving the starting performance. For example, Japanese Patent Publication No. 2004-362861 (Patent Document 1) shows such a structure. Figure 6 As shown in detail, the electrode 3 is composed of a main body 5 and an electrode core wire 4 , and a coil 6 made of linear tungsten is wound around the main body 5 .

[0005] like Figure 6 As shown in (A), the coil 6 is a structure in which a coil made of linear tungsten is wound multiple times around the main body 5 of the electrode 3. When the lamp is started, the so-called cavity effect is generated by the concave and convex shapes between adjacent coils 6, and the coil 6 functions as the starting point (starting position). In addition, the coil 6 has a thin diameter, so it is easy to be heated, and it also has the effect of facilitating the transition from glow discharge to arc discharge.

[0006] However, in recent years, in the pursuit of higher output and longer life of lamps, it has been found that in such a coiled shape, crater-like depressions are formed between the coils, which causes the lamp to blacken and deteriorate in life.

[0007] like Figure 6 As shown in (B), an electric field concentration is generated in the gap formed between adjacent coils 6, 6, resulting in a starting point discharge, whereby the coil 6 is overheated, tungsten evaporates to form a crater-shaped depression 7, and the tungsten evaporate W is directly directed toward the light-emitting tube 2. The evaporated product W is accumulated on the inner wall surface of the light-emitting tube 2 near the coil, and the accumulation of the tungsten evaporated product W continues to produce blackening 8.

[0008] Prior Art Literature

[0009] Patent Literature

[0010] Patent Document 1: Japanese Patent Application Publication No. 2004-362861 Summary of the invention

[0011] Problems to be solved by the invention

[0012] In view of the above-mentioned problems of the prior art, an object of the present invention is to provide a lamp structure capable of avoiding the occurrence of blackening due to evaporation of a coil as a starting member without deteriorating the starting performance of a short arc discharge lamp.

[0013] Solutions to Solve Problems

[0014] In order to solve the above problems, the short arc discharge lamp of the present invention is characterized in that the electrode is composed of an electrode core wire and an electrode body formed at the front end of the electrode core wire and thicker than the electrode core wire, and a single-layer annular member is provided to surround the electrode body.

[0015] Furthermore, the electrode body has an expanded diameter portion at a front end thereof, and the annular member is provided on the electrode body at a position separated from the expanded diameter portion.

[0016] In addition, the present invention is characterized in that the annular member has a shape having a slit in a portion in the circumferential direction.

[0017] Effects of the Invention

[0018] According to the short arc discharge lamp of the present invention, a single-layer annular component is provided on the main body of the electrode, and the gap between the annular component and the main body of the electrode is used as the generation area of ​​the starting point discharge to ensure the starting performance based on the cavitation effect, and the evaporation of tungsten generated by the starting point electrons is not directed to the side of the sealing wall but to the side of the discharge space, so that the blackening of the sealing wall can be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a diagram of the electrode structure of the short arc discharge lamp of the present invention.

[0020] Figure 2 This is a diagram of the electrode tip portion of another embodiment of the present invention.

[0021] Figure 3 It is a side view showing the effect of the present invention.

[0022] Figure 4 This is a diagram of the electrode tip portion of yet another embodiment of the present invention.

[0023] Figure 5 This is an overall view of a conventional short arc discharge lamp.

[0024] Figure 6 yes Figure 5An enlarged cross-sectional view of the main parts (A) and an illustration of a malfunction (B).

[0025] Description of symbols

[0026] 1: Short arc discharge lamp

[0027] 2: LED

[0028] 3: Electrode

[0029] 4: Electrode core wire

[0030] 5: Electrode body

[0031] 5a: Expansion

[0032] 10: Ring member

[0033] 11: Welding marks

[0034] 12: Gap

[0035] W: (Tungsten) evaporation DETAILED DESCRIPTION

[0036] Figure 1 (A) is a side view of an electrode used in a short arc discharge lamp of the present invention, Figure 1 (B) is another example of an electrode having an electrode body having a different shape.

[0037] exist Figure 1 In (A), the electrode 3 is composed of an electrode core wire 4 and a thick-diameter electrode main body 5 formed at the front end of the electrode core wire 4, and an annular member 10 is provided in a manner surrounding the electrode main body 5. The annular member 10 is composed of a tungsten wire, is a single-layer ring-shaped member, and its cross-sectional shape is approximately circular. Here, the approximately circular shape includes not only a circular shape but also an elliptical shape.

[0038] Figure 1 (B) is an example in which the shape of the electrode body 5 is different. In this example, an expanded diameter portion 5a having an expanded diameter is further provided on the front end side of the electrode body 5. The above-mentioned electrode structure is an electrode structure corresponding to high power.

[0039] In this example, the annular member 10 is provided in the electrode body 5 at a position separated from the expanded diameter portion 5a formed by expanding the diameter of the front end of the electrode body 5. That is, the gap between the expanded diameter portion 5a and the annular member 10 is separated to such an extent that a cavitation effect does not occur, and the gap does not become a generating region of the starting point discharge.

[0040] exist Figure 1 As can be seen from the example of (B), the separation distance between the expanded diameter portion 5a and the annular member 10 is preferably 0.04 mm or more, and blackening occurs when it is smaller than this.

[0041] Figure 2 Another example of the annular member 10 is shown. Figure 2 In (A), the annular member 10 is wound around the electrode body 5 in a state of slightly overlapping, and the overlapping portion is welded by laser or the like (recognized as a weld mark 11).

[0042] Figure 2 The structure (B) is a structure in which the annular member 10 has a gap 12 in a part of the circumferential direction. The gap 12 is not a gap where the electric field is concentrated to generate a spark, but needs to be a gap of a predetermined size, more specifically, preferably 0.04 mm or more.

[0043] Figure 3 To explain the effect of the present invention, a gap is formed between the electrode body 5 of the electrode 3 and the annular member 10, and an electric field concentration is generated in this area during lighting and starting, and a spark is generated in this area to start the lighting. In addition, the tungsten evaporated product W generated in this area is directed toward the electrode axial direction, rather than directly toward the inner wall surface of the light-emitting portion, which can suppress the blackening caused by the accumulation of the evaporated product W.

[0044] The cross-sectional shape of the annular member 10 is not limited to a circular shape, and may be Figure 4 The rectangular shape shown in the figure may also be a polygonal shape such as a hexagonal shape or an octagonal shape (not shown). Figure 4 The rectangular ring-shaped member 10 shown is arranged so that a small gap is formed between one side thereof and the electrode main body 5 .

[0045] In this embodiment as well, electric field concentration occurs in the region of the minute gap between the electrode body 5 and the annular member 10, and sparks are generated to start lighting.

[0046] As described above, in the short arc type discharge lamp of the present invention, the electrode is composed of an electrode core wire and a thick-diameter electrode main body formed at the front end thereof, and a single-layer annular member is provided in a manner surrounding the electrode main body, so that an electric field concentration is generated in the gap between the annular member and the electrode main body, which becomes a spark to start the lighting. In addition, the tungsten evaporated product generated in this area is directed toward the electrode axial direction, not directly toward the inner wall surface of the light-emitting tube, so that blackening caused by the accumulation of the evaporated product can be suppressed.

Claims

1. A short arc discharge lamp comprising a pair of electrodes disposed opposite to each other and spaced apart from each other in a light emitting tube, characterized in that: The electrode is composed of an electrode core wire and a thick-diameter electrode main body formed at the front end of the electrode core wire. A single-turn annular member is provided to surround the electrode main body, and a gap is formed between the electrode main body and the annular member.

2. The short arc discharge lamp according to claim 1, characterized in that: The electrode body has an expanded diameter portion at a front end thereof, and the annular member is provided on the electrode body at a position separated from the expanded diameter portion.

3. The short arc discharge lamp according to claim 1 or 2, characterized in that: The annular member has a shape having a slit in a portion in the circumferential direction.

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