Method of Manufacturing Miniature Tipless Halogen Lamp and Apparatus for Carrying Out the Same

1. Field of the Invention:

The present invention relates to a method of manufacturing a miniature tipless halogen lamp of a diameter within the range of some 1.0 to 4.0 mm, capable of radiating intensive white light and being employed in apparatus employing an optical fiber cable, such as sensors, automatic controllers, industrial robots and medical appliances, particularly, endoscopes, for illumination through an optical fiber cable, and an apparatus for carrying out the method.

2. Description of the Prior Art:

In manufacturing a conventional miniature halogen lamp, a gas introducing pipe (designated generally as "tip" in the related industry, and hence will be referred to as "tip" hereinafter) is fused off to seal the lamp bulb after introducing a gas into the lamp bulb. Accordingly, when the internal pressure of the lamp bulb increases above the atmospheric pressure due to heating for fusing-off the tip and the resultant thermal expansion of the gas introduced into the lamp bulb, the gas spouts through the fused tip, and hence it is impossible to seal the lamp bulb. Therefore, when the internal pressure of the lamp bulb needs to be higher than the atmospheric pressure, the lamp bulb containing the gas needs to be cooled by liquid nitrogen or the like in sealing the lamp bulb by fusing-off the tip. Furthermore, according to the prior art, since a discharge pipe and the tip are provided in the head or the bottom of the lamp bulb and the discharge pipe and the tip are fused off after use, the traces of the discharge pipe and the tip remains inevitably in the finished lamp. Still further, when the tip is formed in the head of the lamp bulb, it is impossible to formalize the lamp as the natural consequence, while it is impossible to form the tip in the bottom of the bulb because the lead wires need to be provided in the bottom of the bulb with a very small gap therebetween to form a very small lamp. Accordingly, it has been impossible to provide a lens in the head of a miniature halogen lamp or to formalize miniature halogen lamps.

Accordingly, it is an object of the present invention to provide a method of manufacturing a miniature tipless halogen lamp of very small size as compared with the conventional miniature halogen lamps.

It is another object of the present invention to provide an apparatus for manufacturing such a miniature tipless halogen lamp.

According to the present invention, a gas introducing sealed box and a heat-sealing sealed box are combined in an integral unit and a plurality of lamp bulbs are sealed simultaneously by means of a carbon plate without fusing off the lamp bulbs. Thus, the present invention is capable of manufacturing a plurality of high-quality miniature halogen lamps of uniform performance at a time.

The above and other objects, features and advantages of the present invention will become more apparent from the following description of a preferred embodiment thereof taken in conjunction with the accompanying drawings.

FIG. 1 is a sectional view of a miniature tipless halogen lamp manufacturing apparatus, in a preferred embodiment, according to the present invention;

FIG. 2 is a partly cutaway plan view of the miniature tipless halogen lamp manufacturing apparatus of FIG. 1, as viewed from the side of a halogen gas introducing sealed box (A), in which part of a carbon jig is shown; and

FIGS. 3 (a), 3 (b), 3 (c), 3 (d), 3 (e), 3 (f), 3 (g) and 3 (h) are illustratings of assitance in explaining steps of assembling a miniature tipless halogen lamp according to the present invention.

FIG. 1 is a sectional view of a miniature tipless halogen lamp manufacturing apparatus according to the present invention, including a double-box structure consisting of a hologen gas introducing sealed box A and a heat-sealing box B. The halogen gas introducing box A is a corrosion resistant box, while the heat-sealing sealed box B is a high-pressure vessel.

In FIGS. 1 and 2, there are shown: a halogen gas supply pipe 1 formed of a corrosion-resistant metal for supplying a corrosive gas into the halogen gas introducing sealed box A; a gas discharge pipe 2 formed of the same material as the halogen gas supply pipe 1; a pressure gauge 3 for indicating the pressure of the halogen gas prevailing within the halogen gas introducing sealed box A; a bellows valve 4 for maintaining the perfect airtightness of the halogen gas introducing sealed box A; fastening bolts 5; corrosion-resistant O-rings 6 for holding lamp bulbs and for maintaining the perfect airtightness of the halogen gas introducing sealed box A and the heat-sealing sealed box B; O-ring fastening rings 7 interposed between the corrosion resistant O-rings 6 and a corrosion-resistant O-ring fastening plate 8 for correctly fastening the O-rings 6; clamps 9 for airtightly fastening the halogen gas introducing sealed box A and the heat-sealing sealed box B together in a single unit; O-rings 10 for sealing the halogen gas introducing sealed box A and the heat-sealing sealed box B; the bottom plate 11 of the halogen gas introducing sealed box A; an O-ring 12 for the bellows valve; a heat-insulating plate 13; a carbon plate 14 having heat weirs 33 and several holes 34 for heating the sealed portions at a uniform temperature, and a plurality of sealing holes 36; an electrode 15 for supplying an electric current to the carbon plate 14; a cooling plate 16 for holding lamp bulbs and for cooling the heads of the lamp bulbs so that the halogen gas is sealed in the lamp bulbs at a high concentration; an O-ring 17 for sealing the heat-sealing sealed box B; an insulating ring 18 for insulating the heat-sealing sealed box B from the electrode 15; a heat-resistant O-ring 19 for sealing a hole formed in the heat-sealing sealed box B for receiving the electrode 15 therethrough; a nut 20 for fastening the heat-resistant O-ring 19; an inert gas supply pipe 21; a valve 22 provided in an evacuating pipe 23 connected to a high-vacuum exhauster, not shown; a cooling plate supporting bed 24; a cooling liquid circulating pipe 25 for circulating a cooling liquid through a cooling block 28 as indicated by arrows; bolts 29 fastening the cooling plate 16 and the cooling block 28 together; a pressure gauge 30 for indicating the gas pressure prevailing within the heat-sealing sealed box B; corrosion-resistant electric heaters 31 for heating the interior of the halogen gas introducing sealed box A to raise the pressure of the halogen gas supplied into the halogen gas introducing sealed box A so that the halogen gas is sealed in the lamp bulbs C-8 at a high concentration; screws 32 fastening the electrode 15 to the carbon plate 14; screws 35 fastening the cooling block 28; and a plurality of bulb sealing holes 36 formed in the carbon plate 14 for sealing a plurality of the lamp bulbs C-8 at a time.

The fastening plate 8 is provided with a plurality of holes in alignment with the bulbs sealing holes 36 formed in the carbon plate 14 to supply a halogen gas into the lamp bulbs C-8 therethrough.

A plurality of holes are formed in the heat insulating plate 13 so as to align with the sealing holes 36 of the carbon plate 14.

A thermoelectric thermometer 40 is provided beside the carbon plate 14 with the measuring element, not shown, thereof disposed at a position corresponding to the bead positioned in the lamp bulb C-8 for the heat-sealing process as illustrated in FIG. 1. The thermoelectric thermometer 40 is connected to a temperature controller, which regulates the temperature of the carbon plate 14.

FIGS. 3 (a) to 3 (h) illustrates a series of processes for assembling the miniature tipless halogen lamp according to the present invention. FIG. 3 (a) is a sectional view showing a combination of lead wires C-1 and a bead C-2 put in place on a bead heating carbon plate C-3 and a lead wire holding carbon jig C-4 for fusing the bead C-2. FIG. 3(b) shows lead wires C-1 and the bead C-2 after the bead C-2 has been fused and joined to the lead wires C-1. FIG. 3 (c) is a sectional view of an assembly of the lead wires C-1, the bead C-2 and a filament C-6, in which to fasten the opposite ends of the filament C-6, the respective inner ends C-7 of the lead wires C-1 are bent and crimped to fasten the opposite ends of the filament C-6 to the lead wires C-1. FIG. 3 (d) is a sectional view of a lamp bulb C-8 having a lens C-9. The lamp bulb C-8 serves also as a gas introducing pipe during the assembling process. FIG. 3 (e) is a sectional view of a combination of the assembly of the lead wires C-1, the bead C-2 and the filament C-6, and the lamp bulb C-8, put in place for sealing the lamp bulb C-8. FIG. 3 (f) is a sectional view of the assembly of the lead wires C-1, the bead C-2, the filament C-6 and the lamp bulb C-8, in which the bead C-2 and a portion of the lamp bulb C-8 corresponding to the bead C-2 are fused together to seal the lamp bulb C-8. The upper portion of the lamp bulb C-8 above the bead C-2 is out off at a position C-10 after the lamp bulb C-8 has been sealed. FIG. 3 (g) is a sectional view of a complete miniature tipless halogen lamp R. FIG. 3 (h) shows the complete miniature tipless halogen lamp R in the actual size.

A series of steps of manufacturing the miniature tipless halogen lamp R will be described hereinafter with reference to FIGS. 1 and 3 (a) to 3 (g).

First the lead wires C-1 are held on the bead heating carbon plate C-3 and the lead wire holding carbon jig C-4 and the bead C-2 is set in place on the bead heating carbon plate C-3, as illustrated in FIG. 3 (a). Then, the bead heating carbon plate C-3 is heated to fuse the bead C-2 to weld the lead wires C-1 and the bead C-2 together so that an assembly of the lead wires C-1 and the bead C-2 as illustrated in FIG. 3 (b) is produced. Secondly, the respective inner ends, namely, the upper ends as viewed in FIG. 3b, of the lead wires C-1 are pressed flat and crimped to join the filament C-6 to the lead wires C-1, as illustrated in FIG. 3c, and then the respective outer portions, namely, the lower portions as viewed in FIG. 3c, of the lead wires C-1 are bent away from each other to complete a lighting element C-5, as illustrated in FIG. 3c. Then, the lighting element C-5 is put in the lamp bulb C-8 to assemble an unfinished assembly C of the lead wires C-1, the bead C-2, the filament C-7 and the lamp bulb C-8, as illustrated in FIGS. 1 and 3e.

Then, a plurality of such unfinished assemblies C are inserted through the holes of the heat insulating plate 13 and the heat-sealing carbon plate 14 so that the heads of the lamp bulbs C-8 are received and held in the holes of the cooling plate 16, respectively. Then, the O-ring fastening plate 8 is fastened to hold the unfinished assemblies C airtightly in the heat-sealing sealed box B.

Then, the halogen gas introducing sealed box A is mounted on and fastened to the heat-sealing sealed box B by means of the clamps 9. After the halogen gas introducing sealed box A and the heat-sealing sealed box B has been thus fastened together and sealed, the bellows valve 4 and the valve 22 are opened to evacuate the halogen gas introducing sealed box A and the heat-sealing sealed box B, and the cooling liquid is circulated through the cooling block 28. After closing the bellows valve 4 to seal the halogen gas introducing sealed box A, the halogen gas of a predetermined pressure is supplied through the halogen gas supply pipe 1 into the halogen gas introducing sealed box A. On the other hand, the valve 22 is closed, and then an inert gas is supplied through the inert gas supply pipe 21 into the heat-sealing sealed box B until the internal pressure of the heat-sealing sealed box B reaches a predetermined level. Then, an electric current is supplied to the corrosion-resistant heaters 31 provided within the halogen gas introducing sealed box A to heat the halogen gas supplied into the halogen gas introducing sealed box A in order to raise the pressure of the halogen gas, and thereby the halogen gas is introduced into the lamp bulbs C-8 at the highest possible concentration. Then, an electric current is supplied to the carbon plate 14 having the heat weirs and several holes for uniformly heat forming the portions of the lamp bulbs C-8 to be sealed, through the electrode 15 to heat-seal the lamp bulbs C-8 at a suitable temperature under the automatic temperature control of the temperature controller. Upon the completion of the heat-sealing of the lamp bulbs C-8, the power supply to the carbon plate 14 and to the heaters 31 is interrupted to stop heating. According to the present invention, the lamp bulb C-8 is formed beforehand in a predetermined form having the lens C-9 in the head portion, and the extended upper portion above the position C-10, as viewed in FIG. 3 (f), serves as a tip. Thus, the miniature tipless halogen lamp R is completed by cutting off the upper portion of the lamp bulb C-8 above the position C-10, after completely sealing the lamp bulb C-8 at a position corresponding to the bead C-2.

As is apparent from what has been described hereinbefore, the miniature tipless halogen lamp produced by the method of the present invention has a very small external size as compared with the corresponding conventional miniature halogen lamp; for example, the diameter of the smallest conventional miniature halogen lamp is about 4.7 mm, whereas the diameter of the miniature tipless halogen lamp manufactured by the method of the present invention is as small as about 1.0 mm. Although the invention has been described as applied to manufacturing a halogen lamp, naturally, the present invention is applicable to manufacturing halogen lamps, krypton lamps, xenon lamps and other gas-filled lamps. The miniature tipless halogen lamp manufactured by the method of the present invention enables the reduction of the size of apparatus and enables the insertion of the illuminating head employing the miniature tipless halogen lamp of the present invention in a place where is impossible to be illuminated from outside. Thus the miniature tipless halogen lamp of the present invention is effectively applicable to diverse purposes in various industrial fields in combination with optical fibers.

Although the invention has been described in its preferred embodiment with a certain degree of particularity, it is to be understood that many changes and variations are possible in the invention without departing from the scope and spirit thereof.