JP7611560B2 - Lamp sealing method - Google Patents

Description

The present invention relates to a lamp sealing structure, a lamp, and a lamp sealing method.

Conventionally, gas-filled lamps that have been widely used have formed an airtight space inside the arc tube (glass container) by sealing both ends or one end of the arc tube using a pinch seal method.

Examples of gas-filled lamps include halogen lamps used for heating, metal halide lamps used for lighting, ultraviolet lamps for ultraviolet cleaning, and discharge lamps. (Note that Patent Document 1 discloses an example of a "gas discharge lamp.")

For example, in the case of a conventional discharge lamp 1 shown in FIG. 17, a pair of mounts 2 are inserted and both ends of the arc tube 3 are sealed by a pinch seal method, and then an impurity removal process such as heat treatment is performed, and the air is exhausted through an exhaust tube 5 that has been attached to the arc tube 3 in advance so as to communicate with the internal space 4, as shown in FIG. 18. Thereafter, the necessary filling material is placed in the internal space 4, the internal space 4 is put into a negative pressure state, and the exhaust tube 5 is heated and melted to seal the internal space 4 and the exhaust tube 5 is removed, forming the discharge lamp 1.

In addition, in the case of discharge lamps, which use mercury light emitted by generating a discharge between a pair of electrodes in the internal space of the arc tube, or which use light emitted by a luminous metal, or in the case of lamps in which a halide is enclosed in the internal space to prevent the inner surface of the arc tube from blackening while lit, it is necessary to place the necessary filling material in the internal space before exhausting through the exhaust pipe.

JP 2000-306547 A

In the case of conventional gas-filled lamps 1, as shown in Fig. 17, after the internal space 4 is sealed, a "tip portion 6", which is a trace of airtight processing, is formed on the surface of the arc tube 3 facing the internal space 4. This tip portion 6 is the weakest point in terms of strength because it is the location where stress generated in the arc tube 3 is concentrated, and when the lamp 1 is turned on, the temperature rises to about 700°C to 900°C, which causes structural destruction of the silica glass ( _SiO2 ) that is the material of the arc tube 3, resulting in the problem that the arc tube 3 is susceptible to breakage from the tip portion 6.

Furthermore, depending on the type of lamp 1, when the tip portion 6 is exposed to ultraviolet light with a wavelength of 200 nm or less, there is also the problem that the progress of structural destruction of the quartz glass becomes more pronounced.

In addition, because the chip portion 6 is located in a position facing the internal space 4 in which light-emitting portions such as electrodes are provided, the light emitted from the lamp 1 is blocked by the chip portion 6, causing uneven illuminance on the object illuminated by the lamp 1.

The present invention was made in consideration of the above-mentioned problems, and its purpose is to provide a lamp sealing structure, a lamp, and a lamp sealing method that are less likely to cause damage to the light-emitting tube and are less likely to cause uneven illuminance.

According to another aspect of the present invention,
A lamp is provided that includes any of the sealing structures described above.

According to one aspect of the present invention,
1. A method for sealing a lamp, comprising the steps of: sealing at least one end of an arc tube to form an airtight internal space within the arc tube, the method comprising the steps of:
when forming a sealed portion in the light-emitting tube by pinching and sealing the end portion, a communication hole that communicates the internal space with the outside is formed in the end portion in the width direction of the sealed portion,
an exhaust pipe is attached to an outer end of the communication hole, and exhaust is exhausted from the internal space and an enclosed material is enclosed in the internal space through the exhaust pipe;
a base of the exhaust pipe is heated and melted to form a tip portion that closes the communication hole.

According to the lamp sealing structure and sealing method of the present invention, the tip portion that seals and closes the internal space of the light-emitting tube is formed at the outer end of the sealing portion, spaced apart from the internal space. Since the outer end of the sealing portion is relatively cold (e.g., 300°C or less) even when the lamp is emitting light, it is possible to reduce the possibility that structural destruction of the quartz glass will progress during lamp light emission, causing the light-emitting tube to break from the tip portion.

In addition, the tip portion formed on the outer end of the sealing portion is not easily hit by light emitted from the internal space of the light-emitting tube, so even if ultraviolet light with a wavelength of 200 nm or less is emitted depending on the type of lamp, the progress of structural destruction of the quartz glass does not become noticeable.

In addition, because the light emitted from the internal space of the light-emitting tube is less likely to hit the tip, the light emitted from the lamp is blocked by the tip, reducing the possibility of uneven illuminance occurring on the object illuminated by the lamp.

FIG. 1 is a diagram showing a lamp 10 to which the present invention is applied. This is an end view taken along line AA. 1A to 1C are diagrams showing a manufacturing procedure for a lamp 10 to which the present invention is applied. 1A to 1C are diagrams showing a manufacturing procedure for a lamp 10 to which the present invention is applied. 1A to 1C are diagrams showing a manufacturing procedure for a lamp 10 to which the present invention is applied. 2A to 2C are diagrams showing how the ends of the arc tube 12 are pinch sealed in the manufacturing process of the lamp 10. 2A to 2C are diagrams showing how the ends of the arc tube 12 are pinch sealed in the manufacturing process of the lamp 10. 1A to 1C are diagrams showing a manufacturing procedure for a lamp 10 to which the present invention is applied. FIG. 1 is a diagram showing a lamp 10 according to a first modified example. This is an end view along line BB. 10A to 10C are diagrams showing a manufacturing procedure for the lamp 10 according to the first modified example. 13A to 13C are diagrams showing how the end of the arc tube 12 is pinch-sealed in the manufacturing procedure for the lamp 10 according to the first modified example. 13A to 13C are diagrams showing how the end of the arc tube 12 is pinch-sealed in the manufacturing procedure for the lamp 10 according to the first modified example. FIG. 13 is a diagram showing a lamp 10 according to a second modified example. FIG. 13 is a diagram showing a lamp 10 according to a second modified example. FIG. 1 is a diagram showing a halogen lamp to which the present invention is applied. FIG. 1 shows a conventional gas-filled lamp 1. 1A to 1C are diagrams illustrating a manufacturing procedure for a conventional gas-filled lamp 1.

(Structure of Lamp 10)
The structure of a lamp 10 according to an example to which the present invention is applied will be described with reference to Figures 1 and 2. The lamp 10 is a discharge lamp, and is generally composed of an arc tube 12, a pair of electrodes 14, a pair of foils 16, and a pair of lead rods 18.

The light-emitting tube 12 is made of, for example, quartz glass, and has a light-emitting section 20 and a pair of sealing sections 22 extending from the light-emitting section 20. An internal space 24 sealed by the pair of sealing sections 22 is formed within the light-emitting section 20.

A predetermined amount of mercury 25 and a halogen (iodine, bromine, or a mixture of iodine and bromine) is enclosed in the internal space 24 of the light-emitting section 20.

The pair of electrodes 14 are generally rod-shaped members made of tungsten, and are disposed in the internal space 24 with one end of each facing each other. The other end of each electrode 14 is electrically connected to one end of each of the molybdenum foils 16 embedded in each of the sealing portions 22.

The pair of lead rods 18 are generally rod-shaped members made of molybdenum, with one end of each being electrically connected to the other end of each foil 16. The other ends of each of the pair of lead rods 18 extend outward from each sealing portion 22.

Regarding the structure of the sealing portion 22, one of the sealing portions 22 has a communication hole 26 that connects the internal space 24 of the light-emitting tube 12 with the outside.

In addition, a tip portion 28 that closes the communication hole 26 is formed at the outer end of the communication hole 26, i.e., the outer end of the sealing portion 22 in which the communication hole 26 is formed. This tip portion 28 makes the communication hole 26 and the internal space 24 airtight from the outside.

(Manufacturing Procedure of Lamp 10)
Next, a manufacturing procedure for the above-mentioned lamp 10 will be described. First, the arc tube 12 is prepared before sealing, as shown in Fig. 3. The electrodes 14 and the lead rods 18 are attached to the foil 16 by means of welding or the like to form a pair of mounts 30.

Then, the mount 30 is inserted into the end of the light-emitting tube 12 from the electrode 14, and while holding the mount 30 in a predetermined position, one end of the light-emitting tube 12 (the end where the mount 30 is inserted) is pinch-sealed to seal it. This forms one of the sealing parts 22, as shown in FIG. 4.

Next, the other mount portion 30 is inserted into the other end of the light-emitting tube 12, and the other end is pinch-sealed. This forms an internal space 24 in the approximate center of the light-emitting tube 12. At this time, the other end of the light-emitting tube 12 is sealed so that a communication hole 26 is formed that connects the internal space 24 of the light-emitting tube 12 to the outside, rather than being completely sealed, as shown in FIG. 5. This can be achieved, for example, by using a pinch member 50 with a recess 54 formed in part of a pressing surface 52 that presses against and seals the end of the light-emitting tube 12, as shown in FIG. 6 and FIG. 7. Of course, the sealing portion 22 with the communication hole 26 may be formed first, or a pair of sealing portions 22 may be formed almost simultaneously.

The communication hole 26 may be formed anywhere in the width direction of the sealing portion 22 (the radial direction of the light-emitting tube 12 (= the up-down direction in FIG. 2)), but is preferably formed at the end of the sealing portion 22 in the width direction (the end of the light-emitting tube 12 in the radial direction) as shown in FIG. 2. The reason for this is that since the end of the sealing portion 22 in the width direction is an area that is difficult to make airtight due to the thickness of the light-emitting tube 12, it is relatively easy to form the communication hole 26, and furthermore, if the communication hole 26 is formed closer to the center of the sealing portion 22 in the width direction, it becomes even more difficult to make the end of the sealing portion 22 in the width direction airtight.

After the communication hole 26 is formed, as shown in FIG. 8, a pipe-shaped exhaust tube 60 is attached to the outer end of the communication hole 26 (the end of the sealing portion 22 in the light-emitting tube 12) by welding or other means.

Then, exhaust from the internal space 24 of the light emitting tube 12 and filling the internal space 24 with a filling material are performed through this exhaust tube 60. As described above, this filling material can be mercury 25 and a halogen (iodine, bromine, or a mixture of iodine and bromine). Of course, an appropriate filling material is selected depending on the type of lamp 10.

Finally, as shown in FIG. 1, the base of the exhaust pipe 60 is heated and melted to form a tip portion 28 that closes the communication hole 26. This tip portion 28 is formed at the outer end of the communication hole 26, that is, the outer end of the sealing portion 22 in which the communication hole 26 is formed. This makes the communication hole 26 and the internal space 24 airtight from the outside, and the lamp 10 is completed.

When a predetermined high voltage is applied to a pair of lead rods 18 provided on the lamp 10, the glow discharge that starts between a pair of electrodes 14 arranged in the internal space 24 of the light-emitting part 20 transitions to an arc discharge, and light (mainly ultraviolet light) is emitted by the mercury 25 that is evaporated and excited by this arc.

(Features of Lamp 10)
According to the sealing structure and sealing method of the lamp 10 to which the present invention is applied, the tip portion 28 that seals and closes the internal space 24 of the arc tube 12 is formed at the outer end of the sealing portion 22, spaced apart from the internal space 24. Since the outer end of the sealing portion 22 is at a relatively low temperature (e.g., 300° C. or less) even when the lamp 10 is emitting light, it is possible to reduce the possibility that structural destruction of the quartz glass will progress during light emission by the lamp 10, causing the arc tube 12 to break from the tip portion 28.

In addition, the tip portion 28 formed at the outer end of the sealing portion 22 is not easily hit by the light emitted from the internal space 24 of the light-emitting tube 12, so even if ultraviolet rays with wavelengths of 200 nm or less are emitted depending on the type of lamp 10, the progress of structural destruction of the quartz glass does not become noticeable.

Furthermore, since the light emitted from the internal space 24 of the light emitting tube 12 is unlikely to strike the tip portion 28, the light emitted from the lamp 10 is blocked by the tip portion 28, reducing the possibility of uneven illuminance occurring on the object illuminated by the lamp 10.

(Variation 1)
In the lamp 10 according to the embodiment described above, the communication hole 26 is formed in at least one of the sealing portions 22, and the exhaust pipe 60 is connected to the outer end of the communication hole 26. Alternatively, as shown in Figures 9 and 10, the exhaust pipe 60 may be embedded in at least one of the sealing portions 22. In this case, it is preferable to use quartz glass, the same as the light emitting tube 12, as the material for the exhaust pipe 60.

For the lamp 10 according to this modified example 1, the description of the lamp 10 will be used for the configurations that are the same as those of the lamp 10 according to the embodiment described above, and only the configurations that differ will be described.

In at least one sealing portion 22 of the lamp 10 according to the first modification, an exhaust pipe 60 is embedded that connects the internal space 24 of the light-emitting tube 12 to the outside, and a tip portion that closes the exhaust pipe 60 is formed at the outer end of the exhaust pipe 60 (i.e., the outer end of the sealing portion 22).

Next, the manufacturing procedure for the lamp 10 according to the first modified example will be described. In the description of this manufacturing procedure, the same procedures as those for the lamp 10 according to the above-described embodiment will be referred to, and only the procedures that differ will be described.

When forming at least one sealing portion 22, as shown in Figures 11 to 13, the mount portion 30 and the exhaust pipe 60 are inserted into the end of the light-emitting tube 12, and the end is pinch-sealed. This results in a state in which the internal space 24 of the light-emitting tube 12 is in communication with the outside via the exhaust pipe 60 embedded in the sealing portion 22.

Thereafter, the internal space 24 of the light-emitting tube 12 is evacuated through the exhaust pipe 60, and the internal space 24 is filled with a substance. As mentioned above, the substance may be mercury 25 or a halogen (iodine, bromine, or a mixture of iodine and bromine). Of course, an appropriate substance is selected depending on the type of lamp 10.

Finally, the exhaust pipe 60 is heated and melted at the outer end of the sealing portion 22 to form a tip portion 28 that closes the exhaust pipe 60. This makes the exhaust pipe 60 and the internal space 24 airtight from the outside, completing the lamp 10 (see Figures 9 and 10).

(Variation 2)
Furthermore, in the case of the lamp 10 according to the embodiment described above (lamp 10 having the communication hole 26), after the manufacture of the lamp 10 is completed, the communication hole 26 may be further heated from the outside to close the communication hole 26. This makes it possible to prevent the filler (e.g., mercury or halide) of the lamp 10 from collecting inside the communication hole 26, which has a relatively low temperature, which would reduce the amount of light emitted by the lamp 10 or inhibit the halogen cycle.

The communication hole 26 may be blocked in its entirety (see FIG. 14), or only the end of the communication hole 26 that is closer to the internal space 24 of the light-emitting tube 12 may be blocked (see FIG. 15).

(Variation 3)
In the above embodiment, a case has been described in which the lamp 10 is configured as a discharge lamp, but the lamp 10 is not limited to a discharge lamp, and may be a halogen lamp as shown in Fig. 16, a single-electrode dielectric barrier discharge lamp, or an electrodeless discharge lamp. Furthermore, it may be a dielectric barrier discharge lamp. In other words, the present invention can be applied to any lamp that has at least one sealing part and seals a gas in a sealed internal space, regardless of whether it has electrodes or not.

In this way, the lamp 10 may be configured with at least one sealing portion 22, or conversely, a communication hole 26 and a tip portion 28 may be formed in both of a pair of sealing portions 22, or the exhaust pipe 60 may be embedded and a tip portion 28 may be formed. Also, the mount portion 30 (electrode 14, foil 16, and lead rod 18) is not an essential component.

In addition, the shape of the light emitting tube 12 (particularly the light emitting portion 20) is not limited to a perfectly circular cross section as in the above-described embodiment, but may be, for example, an elliptical cross section or a rectangular cross section.

The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is indicated by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims.

Reference Signs List 10: lamp, 12: arc tube, 14: electrode, 16: foil, 18: lead rod, 20: light emitting portion, 22: sealing portion, 24: internal space, 25: mercury, 26: communication hole, 28: tip portion, 30: mount portion, 50: pinch member, 52: pressing surface, 54: recess, 60: exhaust pipe

Claims (1)

1. A method for sealing a lamp, comprising the steps of: sealing at least one end of an arc tube to form an airtight internal space within the arc tube, the method comprising the steps of:
when forming a sealed portion in the light-emitting tube by pinching and sealing the end portion, a communication hole that communicates the internal space with the outside is formed in the end portion in the width direction of the sealed portion,
an exhaust pipe is attached to an outer end of the communication hole, and exhaust is exhausted from the internal space and an enclosed material is enclosed in the internal space through the exhaust pipe;
a base of the exhaust pipe is heated and melted to form a tip portion that closes the communication hole.

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