JP2005259386A - Manufacturing method of high-pressure discharge lamp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a high pressure discharge lamp which can prevent as much as possible deviation of axial center of both electrodes and ununiformity of the shape of the both electrode tips. <P>SOLUTION: A part of an electrode shaft element 52 is cut into an electrode shaft element 52A and an electrode shaft element 52B by laser cutting with a cutting width D2 [(c) cutting process]. Laser beams LB3, LB4 are irradiated respectively on the tip portion of the electrode shaft element 52A and the tip portion of the electrode shaft element 52B, and the tip portions are melted and shrunken [(b) melting process]. Thereby, a prescribed distance of electrodes D1 is established. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a high-pressure discharge lamp.

  High-pressure discharge lamps, particularly short arc type high-pressure discharge lamps with a short distance between electrodes, are suitably used as light sources for liquid crystal projectors and the like. The short arc type high-pressure discharge lamp literally has a short arc length and can realize a pseudo-point light source, thus improving the light collection efficiency when combined with an optical system such as a concave reflector and the high brightness of the screen projected on the screen. This is because it can be realized.

  Conventionally, a first electrode assembly in which an electrode, a metal foil, and a lead wire are joined in this order from one of side tube portions extending at both ends of a main tube portion having a substantially spherical shape or a substantially spheroid shape. After the electrode is inserted at the head, the one side tube portion is sealed, and then the other side tube portion is aligned with the first electrode assembly (adjustment of the distance between the electrodes). , A method of manufacturing a discharge lamp in which a second electrode assembly having the same configuration as the first electrode assembly is inserted, and the other side tube portion is sealed to form a pair of electrodes (“first 1) ”) is adopted. In addition, said sealing is performed by crimping the side tube part corresponding to the said metal foil, after heating and softening a side tube part.

  By the way, in recent years, as the performance of liquid crystal projectors and the like has been improved, a high-pressure discharge lamp having a shorter arc length has been demanded, and the distance between the electrodes is required to be 1 mm or less. However, in the first manufacturing method described above, since the second electrode assembly is sealed after the second electrode assembly is aligned, the side tube portion generated at the time of sealing is removed. Due to thermal expansion or pressure applied during pressure bonding, the combined position (distance between electrodes) may be shifted. As described above, when the stricter accuracy is required as the distance between the electrodes is shortened, it is difficult to cope with the first manufacturing method.

Therefore, in order to solve the above problems, Patent Document 1 discloses two manufacturing methods.
One of them is, first, after sealing the first electrode assembly and the second electrode assembly to the respective side tube portions so that the inter-electrode distance is smaller than a predetermined inter-electrode distance, This is a manufacturing method (referred to as a “second manufacturing method”) including a step of adjusting the distance between the electrodes to a predetermined distance by melting the tip of the electrodes with laser light irradiated from the outside of the main tube.

  The other is that a main electrode is formed by integrally forming the first electrode assembly and the second electrode assembly on the same axis so that both electrodes face each other. After inserting into the glass tube in which the side tube part is extended from both ends of the part, both side tube parts are sealed, and then, one place of the electrode assembly is irradiated with laser light irradiated from the outside of the main tube part This is a manufacturing method (referred to as “third manufacturing method”) including a step of setting a predetermined distance between electrodes by melting and cutting. Here, from the description of Patent Document 1, “melting and cutting” in this case means that a member melted by heating is broken by surface tension and degenerates to the first electrode side and the second electrode side, respectively. It is understood to say.

And according to patent document 1, in the 2nd and 3rd manufacturing method, after passing through the sealing process of the part used as both electrodes, the process which sets the distance between electrodes is provided, Therefore The said 1st manufacture It is said that the problem that the distance between the electrodes due to the sealing caused by the method varies can be solved.
Japanese Patent No. 3465750 (Claims 1 and 2) Japanese Patent No. 3330592

However, in the second manufacturing method, since the first electrode assembly and the second electrode assembly are sealed separately, there is a possibility that the axis between the two electrode assemblies (between the two electrodes) is shifted. .
On the other hand, in the third manufacturing method, the axis center between both electrodes is less likely to be displaced, but the position to be broken by the surface tension is unstable, and as a result, the amount remaining on the first electrode side of the molten member It has been confirmed by the present inventor that a problem arises in that an unbalance occurs with the amount remaining on the second electrode side and the tip shapes of both electrodes become non-uniform (asymmetric).

  In view of the above problems, an object of the present invention is to provide a method of manufacturing a high-pressure discharge lamp that can prevent the axial misalignment between both electrodes and the unevenness of the tip shapes of both electrodes as much as possible.

  In order to achieve the above object, a method for manufacturing a high-pressure discharge lamp according to the present invention includes a glass tube in which side tube portions are extended from both ends of a main tube portion, a portion serving as a first electrode, and a second electrode. An insertion step of inserting one electrode shaft element including a portion to be an electrode so that the portions to be the first and second electrodes are located in the main pipe portion, and sealing the both side pipe portions Then, a sealing step for sealing the main pipe portion, a cutting step for cutting the electrode shaft element body by a laser between a portion to be the first electrode and a portion to be the second electrode, And a melting step of melting and degenerating a portion to be the first electrode and a tip portion of the portion to be the second electrode separated by the cutting.

Further, in the cutting step, the electrode shaft element is cut with a substantially uniform cutting width.
Further, in the cutting step, the electrode shaft element body is cut by irradiating a laser beam substantially perpendicularly to the axis of the electrode shaft element body from the outside of the main pipe portion.
Further, at the time when the sealing step is completed, the main pipe portion has a substantially spherical shape or a substantially spheroid shape with the axis of the electrode shaft element body as a central axis, and in the cutting step, The laser beam is irradiated from the most bulged portion with respect to the central axis of the main pipe portion.

The melting step may be performed by irradiating the tip portion of the portion serving as the first electrode and the tip portion serving as the second electrode with a laser beam.
Alternatively, the melting step may be performed by discharging between the portion serving as the first electrode and the portion serving as the second electrode.
Alternatively, the melting step is performed by preliminarily melting the tip portion of each of the first electrode portion and the second electrode portion with a laser beam, and after the preliminary melting step. In addition, a main melting step of discharging between a portion serving as the first electrode and a portion serving as the second electrode may be included.

  Alternatively, the melting step includes a preliminary melting step of pre-melting a portion that becomes the first electrode and a portion that becomes the second electrode by irradiating a laser beam with the laser beam, and the preliminary melting step. Thereafter, a main melting step of discharging between a portion to be the first electrode and a portion to be the second electrode may be included.

  According to the method for manufacturing a high-pressure discharge lamp according to the present embodiment, one electrode shaft element is inserted into a glass tube, both side tube parts are sealed, and after sealing, the electrode shaft element is cut. Therefore, it is difficult for an axial misalignment to occur between the completed electrodes. Then, after cutting, the tip of the portion serving as the first electrode and the tip of the portion serving as the second electrode are melted, so that the tip portions of both electrodes can be processed into substantially the same shape. Become.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing a schematic configuration of a high-pressure mercury lamp 10 (hereinafter simply referred to as “lamp 10”) to be manufactured by the manufacturing method according to the present embodiment. FIG. 1 is a view in which only a glass bulb 12 described later is cut along a plane including its axis. Moreover, the scale between each component is not unified in all the drawings including FIG.

As shown in FIG. 1, the lamp 10 includes a glass bulb 12 having a discharge chamber (light emitting space) 14 hermetically sealed. The glass bulb 12 is made of quartz glass.
Further, the lamp 10 has a pair of electrodes 16 and 18 which are disposed in the discharge chamber 14 with their tip portions facing each other. The first electrode 16 is formed by winding a coil 22 around an electrode shaft 20. Similarly, the second electrode 18 is formed by winding a coil 26 around an electrode shaft 24.

The base ends of the electrode shafts 20 and 24 are supported by the glass bulb 12, and each of the electrode shafts 20 and 24 extends substantially coaxially to the discharge chamber 14, and each coil is formed at the tip portion thereof. 22 and 26 are wound. Each of the coils 22 and 26 is provided to exhibit an appropriate heat dissipation function and prevent overheating of the electrodes when the lamp 10 is turned on.
In addition, a part of the opposing tip portion of the first electrode 16 and the second electrode 18 is processed into a substantially hemispherical shape to form heads 28 and 30 as described later. The reason for processing into a substantially hemispherical shape is to concentrate the discharge at the time of lighting as much as possible at the tip of the head to prevent a so-called arc jump phenomenon in which the arc is displaced randomly. Of course, in order to prevent the arc jump phenomenon, the tip shape is “substantially hemispherical” as an example, and may be, for example, substantially spherical or substantially conical.

The distance between the tips of both heads 28 and 30 in the tube axis direction of the glass bulb 12, that is, the inter-electrode distance D1 is 1.0 to 1.5 mm. The electrode shafts 20 and 24 have a diameter of 0.4 mm, and the coils 22 and 26 have an outer diameter of 1.2 mm. The electrode shafts 20 and 24 and the coils 22 and 26 are both made of tungsten.
The end portions of the electrode shafts 20 and 24 opposite to the head portions 28 and 30 are joined to one end portions of strip-shaped metal foils 32 and 34. Each of the pair of metal foils 32 and 34 is made of molybdenum foil.

  One end portion of the first external lead wire 36 is joined to the other end portion of the first metal foil 32, and a second external portion is connected to the other end portion of the second metal foil 34. Lead wire 38 is joined. The end portions of the first and second external lead wires 36 and 38 opposite to the metal foils 32 and 34 are exposed from the glass bulb 12, and power is supplied from the end portions, whereby the lamp 10 can be turned on. The first and second lead wires are both made of molybdenum wires.

The glass bulb 12 is sealed mainly at portions corresponding to the metal foils 32 and 34, and the hermetically sealed discharge chamber 14 is formed.
The discharge chamber 14 is filled with mercury 40 as a luminescent material and a rare gas (not shown) such as argon, krypton, and xenon as a starting aid, and a halogen material (not shown) such as iodine and bromine. Yes. The halogen substance serves to suppress the blackening of the glass bulb by returning to the electrodes 16 and 18 without attaching tungsten evaporated from the electrodes 16 and 18 to the inner surface of the quartz glass bulb 12 by a so-called halogen cycle. Is to be enclosed.

Then, the manufacturing method of the lamp | ramp 10 which consists of said structure is demonstrated.
As shown in FIG. 2, first, a glass tube 42 for the lamp 10 (hereinafter simply referred to as “glass tube 42”) and an electrode assembly 44 are prepared.
The glass tube 42 is a member that becomes the glass bulb 12, for example, a main tube portion 46 having a substantially spherical shape or a substantially spheroid shape, and a cylindrical first side extending from both ends thereof. It has a pipe part 48 and a second side pipe part 50. Needless to say, the glass tube 42 is made of quartz glass.

  The electrode assembly 44 is formed by joining the metal foils 32, 34 to both ends of one electrode shaft element body 52, and further joining the external lead wires 36, 38 to the metal foils 32, 34. is there. In addition, a pair of coils including a first coil 54 and a second coil 56 are extrapolated to the electrode shaft element body 52. Here, what is formed by extrapolating the first coil 54 and the second coil 56 to the electrode shaft body 52 is processed into the first electrode 16 and the second electrode 18 as described later. The

  The glass tube 42 configured as described above is set on a jig 58, and as shown in FIG. 2, the electrode shaft assembly 44 is placed on the glass tube 42, and the first coil 54 and the second coil 56 are the main tubes. The electrode 46 is inserted so as to be positioned at the part 46 [electrode assembly inserting step]. More specifically, the electrode shaft assembly 44 is inserted until the middle of the first coil 54 and the second coil 56 in the tube axis direction of the glass tube 42 is located in the middle of the main tube portion 46.

Next, as shown in FIG. 3, a part of each of the side tube portions 48 and 50 is sealed, and the main tube portion 46 is hermetically sealed to form the discharge chamber 14 [sealing step]. The hermetic sealing is mainly performed at portions corresponding to the metal foils 32 and 34.
The sealing step can be realized by the following procedure, for example.
First, the inside of the glass tube 42 is decompressed (for example, about 20 kPa), and the portion corresponding to the metal foil 32 of the first side tube portion 48 while rotating the glass tube 42 around the tube axis 60 in this decompressed state. Is heated with a burner (not shown) and softened. If it does so, the softened part of the 1st side pipe part 48 will shrink | contract, a part of inner surface of the said 1st side pipe part 48 and the metal foil 32 will closely_contact | adhere, and sealing will be made | formed.

Next, after introducing the mercury 40, the rare gas (not shown), and the halogen substance (not shown) into the glass tube 42 (in the main pipe portion 46), the second side tube portion 50 is moved to the first side tube 50. The sealing process is completed by sealing in the same manner as in the case of the side tube portion 48.
When the sealing step is completed, the electrode shaft element body 52 is fixed in a state where the axial center thereof substantially coincides with the tube shaft 60 of the glass tube 42. That is, the axis of the electrode shaft element body 52 substantially coincides with the central axis of the main pipe portion 46.

FIG. 4A is an enlarged view of the main pipe portion 46 and its vicinity at the end of the sealing process. In FIG. 4 and subsequent figures, illustration of mercury 40 in the main pipe portion 46 is omitted.
Subsequent to the sealing step, a cutting step for laser cutting the electrode shaft body 44 is performed.
In the cutting step, a known 300 W class YAG laser oscillator (not shown) is used. The YAG laser oscillator can be switched between pulse oscillation and continuous oscillation.

As shown in FIG. 4A, a laser beam LB1 focused to a spot diameter of 0.1 mm is irradiated approximately perpendicularly to the axis of the electrode shaft element body 52 by an optical system (not shown). Since the beam diameter is smaller than the diameter of the electrode shaft element body 44, the laser beam LB1 is relatively moved in a direction orthogonal to the axis of the electrode shaft element body 44 as shown in FIG. And cut.
Since the cutting is performed by pulse oscillation, as shown in FIG. 5A, the cutting can be performed with a cutting width D2 that is substantially equal to or less than the beam diameter, and the cutting width is the same as that of the laser beam LB1. It becomes substantially uniform in the moving direction. That is, the cutting in the cutting process of the present embodiment is clearly different from the melt cutting in the prior art introduced in the background art section, that is, the cutting in which the member is melted and separated by the surface tension. It becomes cutting of an aspect. Furthermore, in the melt cutting in the prior art, the tip portion after cutting is rounded due to surface tension, and the cutting width is not uniform, whereas the cutting of the present embodiment is substantially uniform. It becomes a cutting of a wide width.

  If the electrode shaft element 52 is to be cut, as shown by a broken line in FIG. 4A, the electrode axis element 52 may be irradiated with a laser beam from an oblique direction (hereinafter, referred to as a broken line). Sometimes simply referred to as “oblique illumination”.) However, in this case, the possibility of variations in the laser beam irradiation position on the electrode shaft body 52 increases for the following reasons. In each figure, the main pipe portion 46 is drawn in the shape of a spherical shell having a uniform thickness for convenience. However, in actuality, the thickness is not uniform for manufacturing reasons, and varies from individual to individual. The variation in thickness increases as the distance from the side tube portions 48 and 50 increases. In the oblique irradiation passing through the position 46B near the side tube portion 50, the variation in the thickness is affected by the variation in the thickness, and the direction of refraction when passing through the glass is increased. Variations occur and the positional relationship between the irradiation position and the focal point and the workpiece varies. Therefore, in the present embodiment, the laser beam is from the position 46A where the influence due to the variation in the thickness of the main pipe portion 46 is the least, that is, from the most bulged portion with respect to the axial center (tube axis 60) of the electrode shaft element body 52. It is going to irradiate.

  In the above example, the circularly focused beam is moved and cut. However, the present invention is not limited to this. For example, as shown in FIG. The laser beam may be shaped and irradiated on a rectangular cross section having a side of 0.1 mm (LB2). This makes it possible to cut the laser beam LB2 without moving it. Even in this case, the cutting width is substantially uniform as in the case described above.

When the cutting process is completed (FIG. 5A), a melting process for setting the distance between the electrodes is executed.
As shown in FIG. 5B, the tip portions of the electrode shaft bodies 52A and 52B cut and separated in the cutting step are irradiated with laser beams LB3 and LB4 to melt the tip portions. In this case, continuous oscillation is used. This is because continuous oscillation is more suitable for melt processing. The beam output is 190 [W], and the irradiation time is 1.5 [seconds]. These conditions are appropriately determined depending on the material of the material to be melted (electrode shaft element, coil), the amount of melting, and the like.

  Further, the irradiation with the laser beam LB3 and the irradiation with the laser beam LB4 may be performed simultaneously or sequentially. In the case of simultaneous, it is not always necessary to use two laser oscillators. One laser beam emitted from one laser oscillator may be split into two by a half mirror or the like to create the laser beam LB3 and the laser beam LB4.

  By irradiation with the laser beams LB3 and LB4, a part (about 1 to 2 turns) of the coils 54 and 56 is also melted, and the melted parts are degenerated toward the respective base ends (support ends) due to surface tension. As shown in FIG. 5 (c), it is rounded to have a substantially hemispherical surface. Due to the degeneration, the required inter-electrode distance D1 (FIG. 5C) is set. When the melted portion is solidified, the electrode 16 and the electrode 18 in which the coil 22 and the electrode shaft 20 and the coil 26 and the electrode shaft 24 are integrally joined are completed.

In the example described above, the tip portions of the electrode shaft bodies 52A and 52B are irradiated with a laser beam and melted. However, the melting method is not limited to laser beam irradiation.
As shown in FIG. 6A, the first external lead wire 36 and the second external lead wire 38 are connected to the lighting device 100 and are melted by discharging between the electrode shaft base bodies 52A and 52B. Also good. As the lighting device 100, a known device can be used.

When power is supplied by the lighting device 100, as shown in FIG. 6B, a discharge is generated between the tips of the electrode shaft base bodies 52A and 52B, and the tip portions are melted.
The discharge time is a time required for the coils 54 and 56 to melt for a predetermined number of turns (for example, one to two turns). The tip portion melted by the discharge is contracted to the base end (support end) side by the surface tension as in the case of melting by laser, and has a substantially hemispherical surface as shown in FIG. So rounded. The electrode distance D1 (refer FIG. 1) required by the said shrinkage | reduction is set, and when the melted part solidifies, the coil 16 and the electrode shaft 20, and the electrode 16 formed by integrally joining the coil 26 and the electrode shaft 24, respectively. The electrode 18 is completed as in the case of laser melting.

  As described above, according to the manufacturing method of the high-pressure mercury lamp according to the present embodiment, one electrode assembly 44 (one electrode shaft element body 52) is inserted into the glass tube 42, and the side tube Since the electrodes 48 and 50 are sealed and the electrode shaft element body 52 is cut after the sealing, the axial misalignment hardly occurs between the completed electrodes. Then, after cutting, the tip of the portion serving as the first electrode and the tip of the portion serving as the second electrode are melted, so that the tips of both electrodes can be processed into substantially the same shape. Become.

As described above, the present invention has been described based on the embodiment. However, the present invention is not limited to the above-described form, and for example, the following form may be possible.
(1) In the above embodiment, the melting step is performed by either laser beam irradiation or discharge. However, the present invention is not limited to this, and both may be used in combination.

For example, the tip portion of the electrode shaft element bodies 52A and 52B (see FIG. 5B) is irradiated with a laser beam, and the electrode shaft element bodies 52A and 52B (in some cases) are less than the final required amount. The coils 54 and 56 are also melted [pre-melting step], and then, as described with reference to FIG. 6, finally, the required amount is melted by the discharge [main melting step].
It is desirable that the cutting width in the cutting process is as narrow as possible. However, if it is too narrow, there may occur a situation in which the melt slightly generated in the cutting process becomes granular and gets caught in the gap (between the cut surfaces). The element itself is completely cut off.) In particular, when laser cutting is performed in an airtight space where the assist gas cannot be used as in the present embodiment, the above situation is likely to occur. Even if power is supplied in such a state, the current flows through the granular melt, and there are cases where good discharge cannot be performed. Therefore, first, the electrode shaft element bodies 52A and 52B are slightly degenerated by the preliminary melting described above to completely separate the tips from each other, and the main melting step by the subsequent discharge is executed.
(2) In (1), in the preliminary melting step, both the electrode shaft bodies 52A and 52B are pre-melted. However, after only one of them is pre-melted, the main melting step by discharge is shifted to. Also good. By doing so, it is possible to shorten the time for alignment and the like for irradiating the laser beam, and the overall manufacturing time of the high-pressure mercury lamp can be shortened.
(3) The present invention is not limited to the above-described method for manufacturing a high-pressure mercury lamp, but can be applied to other high-pressure discharge lamps such as a metal halide lamp and a high-pressure sodium lamp.
(4) Moreover, this invention is applicable not only to what has a coil in an electrode but the manufacturing method of the high pressure discharge lamp by which an electrode is comprised only with a shaft.

  For example, it can be suitably used in a method for manufacturing a short arc type high-pressure discharge lamp.

It is a figure which shows schematic structure of the high pressure mercury lamp which is a manufacturing object. It is a figure for demonstrating an electrode assembly insertion process. It is a figure for demonstrating a sealing process. It is a figure for demonstrating a cutting process. It is a figure for demonstrating the melting process by irradiation of a laser beam. It is a figure for demonstrating the melting process by discharge.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 High pressure mercury lamp 16 1st electrode 18 2nd electrode 42 Glass tube 46 Main pipe part 48, 50 Side pipe part 52 Electrode shaft element body

Claims (8)

One electrode shaft element body including a portion to be a first electrode and a portion to be a second electrode is formed on a glass tube in which side tube portions are extended from both ends of the main tube portion. An insertion step of inserting the second electrode so that a portion to be located in the main pipe portion;
A sealing step of sealing the main pipe part by sealing the both side pipe parts;
A cutting step of cutting the electrode body by a laser between a portion to be the first electrode and a portion to be the second electrode;
A melting step of melting and degenerating a portion to be the first electrode and a tip portion of the portion to be the second electrode separated by the cutting;
The manufacturing method of the high pressure discharge lamp characterized by including.   2. The method of manufacturing a high-pressure discharge lamp according to claim 1, wherein in the cutting step, the electrode shaft body is cut with a substantially uniform cutting width.   3. The cutting step according to claim 1, wherein in the cutting step, the electrode shaft element body is cut by irradiating a laser beam substantially perpendicularly to the axis of the electrode axis element body from the outside of the main pipe portion. A method for manufacturing a high-pressure discharge lamp. At the time when the sealing step is completed, the main pipe portion has a substantially spherical shape or a substantially spheroid shape with the axis of the electrode shaft body as the central axis,
4. The method of manufacturing a high-pressure discharge lamp according to claim 3, wherein, in the cutting step, the laser beam is irradiated from a portion that bulges most with respect to the central axis of the main pipe portion.   5. The melting step is performed by irradiating a laser beam to a tip portion of a portion to be the first electrode and a tip portion to be the second electrode. A method for producing the high-pressure discharge lamp according to item.   5. The melting process according to claim 1, wherein the melting step is performed by discharging between a portion to be the first electrode and a portion to be the second electrode. 6. A method for manufacturing a high-pressure discharge lamp. The melting step includes
A pre-melting step of pre-melting the tip portion of each of the portion to be the first electrode and the portion to be the second electrode by irradiating a laser beam;
After the preliminary melting step, a main melting step of discharging between the portion to be the first electrode and the portion to be the second electrode,
The manufacturing method of the high pressure discharge lamp of any one of Claims 1-4 characterized by the above-mentioned. The melting step includes
A pre-melting step of pre-melting the tip portion of one of the portion to be the first electrode and the portion to be the second electrode with a laser beam;
After the preliminary melting step, a main melting step of discharging between the portion to be the first electrode and the portion to be the second electrode,
The manufacturing method of the high pressure discharge lamp of any one of Claims 1-4 characterized by the above-mentioned.

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