JPS643028B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a tube-shaped light bulb.

In general, tube-type light bulbs are widely used as exposure light sources or fixing heat sources for copying machines, and other illumination light sources.

Particularly when used as an exposure light source for a copying machine, it is necessary to obtain a predetermined light distribution.

In the conventional manufacturing method of a tube-shaped light bulb, as shown in FIG. , Metal foils 12, 1 made of molybdenum etc. are attached to these internal lead rods 11, 11.
The filament assembly 1 is formed by connecting one end of the metal foils 12 and external lead rods 13 and 13 to the other ends of the metal foils 12 and 12, and as shown in FIG. A cylindrical glass tube 2 comprising a protruding tube 21 for the purpose is held vertically by a holder 3, and an external lead rod 13, extending along the tube axis of the glass tube 2, is provided inside the glass tube 2.
The filament assembly 1 is positioned so that the filament parts 13 protrude from the ends 22, 22 of the glass tube 2, respectively. 4 is a holder that holds the upper external lead rod 13 under tight pressure, and 5 is a support base that supports the lower external lead rod 13.

In this state, while flowing a protective gas such as nitrogen or argon into the inside of the glass tube 2 from the protruding tube 21 of the glass tube 2 at a flow rate of, for example, 0.5 to 2/min, the lower end 22 of the glass tube 2 is It is heated from the outside with a heater 6 such as a gas burner to melt it, and in this state, as shown in FIG. metal foil 12
are hermetically welded to the glass portion of the end portion 22 to form one sealing portion. Next, the glass tube 2 with one end sealed in this manner is held in the opposite direction, and the other sealed portion is formed in the same manner as described above. Then, the inside of the glass tube 2 is evacuated via the protrusion tube 21, and then necessary gas is filled into the interior of the glass tube 2 via the protrusion tube 21. Then the protruding tube 2
1 is heated and hermetically sealed to obtain a tube-shaped light bulb as shown in FIG. 21A indicates the remaining protruding portion of the protruding tube 21. As shown in FIG.

However, in such a method, the protrusion tube 21
Even if the projecting pipe portion 21A is removed to make it as short as possible by finally sealing it airtight, the projecting pipe 2
It is quite difficult to completely remove the protruding portion 21A without any adverse effect on the surrounding glass portion of the glass portion 1, and in reality, the protruding portion 21A of about 2 to 5 mm is formed. Therefore, a protruding portion 21A is inevitably formed on the outer wall of the glass tube 2 of the tube-type light bulb obtained by the above-mentioned method due to the glass portion of the protruding tube 21, which prevents the tube-type light bulb from being used in other equipment. The protruding portion 21A may become an obstacle during the installation work and have an adverse effect. For example, when a tube-type light bulb is used as a heat source for fusing in a copying machine, the tube-type light bulb is usually installed inside the fusing roller, and the fusing roller Tube light bulbs are installed and removed through a light bulb insertion slot provided on the side of the fuser.The size of this light bulb insertion slot should be as small as possible in order to prevent heat loss from the fixing roller. Since the tube-type light bulb has a protruding portion 21A, a light bulb insertion opening is required that is equal to the length of the protruding portion 21A added to the outside diameter of the tube-type light bulb, which is extremely difficult to prevent heat loss from the fixing roller. This is a major drawback. On the other hand, when using a tube-shaped light bulb obtained by the above-mentioned method as an exposure light source for a copying machine, it is necessary that the tube-shaped light bulb obtain a predetermined light distribution. Since there is a protruding portion 21A on the side, the direction of the light may be disturbed and a predetermined light distribution may not be obtained, which is a big problem. Since most of the protruding tube 21 is removed and ultimately becomes unnecessary, the cost of materials for this unnecessary glass portion is so large that it cannot be ignored, and this is also a cause of high manufacturing costs.

The present invention has been made based on the above-mentioned circumstances, and it is possible to manufacture a tube-type light bulb without providing a protruding tube for evacuation and gas filling on the outer wall of the glass tube. It is possible to obtain a tube-shaped light bulb without any protruding parts on the outer wall,
Moreover, the aim is to provide a new manufacturing method for tube-shaped light bulbs that allows the final hermetic sealing process to be easily and quickly performed at a precise location. A filament assembly formed by connecting an external lead rod through a foil is placed in a cylindrical glass tube so that the external lead rod protrudes from the end, and the end of the glass tube is heated and the width of the pressing surface is increased. is pressed with a pincher smaller than the outside diameter of the glass tube, thereby forming an airtight welded part where the metal foil of the filament assembly is hermetically welded to the end thereof, and also forming an airtight welded part beyond the airtight welded part to the inside of the glass tube. After forming a pore that communicates with the outside, and exhausting the inside of the glass tube and supplying gas through the pore, the glass portion around the pore is heated while the pressure inside the glass tube is lower than the outside. The method includes a step of heating with a laser beam to close and hermetically seal the pores.

An embodiment of the present invention will be described below with reference to the drawings.

In one embodiment of the present invention, as shown in FIG. 5, a cylindrical glass tube 7 having a uniform shape throughout its length is vertically held by a holder 3 having a gas introduction tube 31 in a part thereof. The entire glass tube 7 extends along the tube axis of the glass tube 7, and the external lead rods 13, 13 at both ends protrude from the ends 71A, 71B of the glass tube 7, respectively, and the metal foil 12 , 12 are the ends 71A and 71B, respectively.
A filament assembly 1 having the same configuration as that shown in FIG. 1 is positioned within the opening. 4 is a holder that holds the upper external lead rod 13 under tight pressure, and 5 is a support base that supports the lower external lead rod 13. In this state, while flowing a protective gas made of nitrogen, argon, etc. from the gas introduction tube 31 toward the bottom of the glass tube 7 from the opening of the upper end 71B of the glass tube 7 at a flow rate of, for example, 0.5 to 2/min, The lower end 71A of the glass tube 7 is heated from the outside with a heater 6 such as a gas burner to melt it, and in this state, from the outer wall surface of the end 71A, as shown in FIG. A pincher 81 whose width L in the direction is smaller than the outer diameter D of the glass tube 7 presses the center of the end 71A to remove the metal foil 12 located inside the end 71A.
As shown in FIG. 7, a flat airtight welded part 72 is formed by airtightly welding the glass part of the glass part 72, and pinchers 81 are formed on both sides of this airtight welded part 72
At the vertically extending side portions 73, 73 which are not in contact with the pressing surfaces of the glass tube 7, pores 74, 74 are formed which penetrate from the inside of the glass tube 7 to the outside of the end portion 71A. Next, as shown in FIG. 8, the glass tube 7 and the filament assembly 1 with one end fixed thereto are reversed, the glass tube 7 is held vertically by the holder 3, and the lower external lead rod 13 is held vertically by the holder 3. Abutting on the support 5, the filament assembly 1 extends vertically along the tube axis, with the lower metal foil 12 located within the lower end 71B and the external lead rod 13 located within the lower end 71B.
Make it protrude from 1B. In this state, the gas introduction tubes 31, 31 are connected to the openings of the pores 74, 74 formed in the upper end 71A, and a protective gas made of nitrogen, argon, etc., for example, is supplied downward to the glass tube 7. While flowing at a flow rate of 0.5 to 2/min, the lower end 71B of the glass tube 7
is heated from the outside by a heater 6 such as a gas burner to melt it, and in this state, from the outer wall surface of the end portion 71B, as shown in FIG. End 71 with pinchers 82 equal to or larger than the outer diameter
The metal foil 12 located within the end portion 71B is hermetically welded to the glass portion of the end portion 71B by pressing the entire portion B, and the entire glass portion is hermetically welded to completely seal the end portion 71B. Stop.

Next, the end portion 71A of the glass tube 7 whose one end is completely sealed in this way, in which the pores 74, 74 are formed, is attached to the exhaust and gas filling head 100 as shown in FIG. . 101 is a stopper that also serves as a current-carrying electrode; 102 is an outer frame of the ventilation hole;
103 is a rubber square ring, 104 and 105 are spacers, 106 is a compression fitting, and glass tube 7
At the end 71A, the external lead rod 13 is inserted into the stopper 101, the openings of the small holes 74, 74 are communicated with the ventilation hole 107, and the square ring 103 abuts the entire circumference of the end 71A, and the compression fitting 106 The glass tube 7 is compressed in the axial direction to maintain airtightness between the ventilation hole 107 and the external space.
In this state, use an air pump etc. to open the ventilation hole 107.
The inside of the glass tube 7 is evacuated through the pores 74 and 74 of the glass tube 7, and then the necessary sealed gas is passed through the vent hole 107 and the pores 7 of the glass tube 7.
4, 74 to the inside of the glass tube 7
The gas is supplied at a predetermined gas pressure lower than that outside. In this state, a laser oscillator 9, which generates a laser beam such as a carbon dioxide laser with a beam diameter of 1 mm and an output of about 100 W,
The laser beam from 9 is passed through the pore 74 of the end 71A,
74 is heated and melted to close at least a portion of the pores 74, 74, and the end 71A is finally completely hermetically sealed, and the tube is closed as shown in FIG. Get a molded light bulb. Note that since the heating by the laser beam is performed in a state where the pressure inside the glass tube 7 is lower than that outside, the heated portion has a recess formed therein and the pores 74 are closed, as shown in FIG. I can escape.

According to the above embodiment, the end 71 of the glass tube 7
When forming the airtight welded part 72 on A, pores 74, 74 are provided on the sides thereof, and the pores 74, 74 are
Since the exhaust and gas filling are performed through the glass tube 7, there is no need for a protruding tube that was conventionally provided in the center of the glass tube for exhausting and gas filling. This eliminates the problems that previously existed when installing tube-type light bulbs into other equipment due to the protruding parts. When installed, the size of the light bulb insertion opening on the side of the fixing roller can be made as small as the outer diameter of the glass tube 7, which can greatly contribute to preventing heat loss from the fixing roller. Furthermore, since there is no protrusion on the outer wall of the glass tube 7, it is possible to prevent the light distribution from being disturbed. For example, when used as an exposure light source for a copying machine, it is possible to reliably obtain the required light distribution. It becomes possible. Furthermore, glass tube 7
This saves material costs by eliminating the need for parts that are ultimately unnecessary and removed, compared to traditional tube bulbs of comparable length, tube outside diameter, and wall thickness. The manufacturing cost can be reduced by about 5%. According to the above method, the pores 74, 74 can be formed by determining the size of the pressing surfaces of the pincher 81 and the distance between the pressing surfaces during pressing.
The pores 74, 74 can be formed extremely easily without requiring any other special means for forming the pores 74, 74.

And the final hermetic sealing of the pores 74, 74,
Since the laser beam is used in a state where the pressure inside the glass tube 7 is lower than the outside, the laser beam has no flame fluctuations or instability unlike gas burners, and has high energy even though the irradiation spot is small. Therefore, only a specific small area can be melted accurately, easily and quickly, and the pores 74, 74 can be hermetically sealed quickly at a precise position, which is extremely convenient for work. At the same time, the metal foil 12 already hermetically welded to the hermetically welded portion 72 is not adversely affected at all.

On the other hand, when the pores are sealed by heating and pressing with a pincher, it is necessary to heat the entire end of the glass tube with a burner. Therefore, the metal foil welded to the airtight welded portion is heated to a temperature close to its melting point and pinch-sealed, so there is a high risk that the foil will break.

Although one embodiment of the present invention has been described above, it is not necessarily necessary to have two pores 74;
One piece is enough.

The inner diameter of the pores 74 is preferably about 0.5 to 1.2 mm, for example. From the point of view of the workability of hermetic sealing using a laser beam, the smaller the inner diameter of the pore 74 is, the better; however, if the inner diameter is less than 0.5 mm, it will take too much time to exhaust and fill the gas, which is undesirable; In some cases, the time required for evacuation and filling the gas is shortened, but it is difficult to produce a laser beam with a large beam diameter, so if the inner diameter exceeds 1.2 mm, it may be difficult to hermetically seal the pore 74. In some cases, it may not be possible to achieve air-tight sealing, and as described above, the optimum inner diameter of the pores 74 is in the range of 0.5 to 1.2 mm for air-tight sealing using laser beams. It is not necessary to completely close the pore 74 along its length, but it is sufficient to close at least a portion of the pore 74 to the extent that airtight sealing can be achieved. The pores 74, 74 may be formed at the other end after one end is completely hermetically sealed.

As described above, according to the method for manufacturing a tube-type light bulb of the present invention, a tube-type light bulb can be manufactured without providing a protruding tube for exhausting and gas filling on the outer wall of the glass tube. It is possible to obtain a tube-shaped light bulb without any protruding parts on the outer wall of the tube, and furthermore, the final hermetic sealing process can be easily and quickly performed at an accurate position without adversely affecting the metal foil. It is possible to provide a novel method for manufacturing a tube-type light bulb.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an example of a filament assembly, FIGS. 2 and 3 are explanatory diagrams showing a conventional method for manufacturing a tube-type light bulb, and FIG. 4 is an explanatory diagram showing a tube-type light bulb obtained by the conventional method. Explanatory sectional view showing an example of
10 are explanatory diagrams showing one embodiment of the method of the present invention, and FIG. 11 is an explanatory diagram of a tube-type light bulb obtained by the method of the present invention. F...Filament, 12...Metal foil, 13...
...External lead rod, 1...Filament assembly, 2
DESCRIPTION OF SYMBOLS 1... Projection tube, 21A... Projection part, 2... Cylindrical glass tube, 22... End part, 6... Heater, 80...
...Pincher, 7...Glass tube, 31...Gas introduction tube, 71A, 71B...End part, 81, 82...
Pinchers, 72... Airtight welded portion, 73... Side parts, 74... Pores, 100... Exhaust and gas filling head, 101... Stopper, 102... Outer frame, 103... Square ring, 106... ...compression fittings,
107...Vent hole, 9...Laser oscillator.

Claims (1)

[Claims] 1. A filament assembly consisting of external lead rods connected to both ends of the filament via metal foil is placed in a cylindrical glass tube so that the external lead rods protrude from the ends, and the ends of the glass tube are heated. At the same time, by pressing with a pincher whose pressing surface width is smaller than the outer diameter of the glass tube, an airtight welded portion is formed in which the metal foil of the filament assembly is airtightly welded to the end portion, and the airtight welded portion is After forming a pore that communicates the inside of the glass tube with the outside through the pore, and exhausting the inside of the glass tube and supplying gas through the pore, the pressure inside the glass tube is lower than that outside. A method for manufacturing a tube-shaped light bulb, comprising the step of heating a glass portion around the bulb with a laser beam to close the pores and hermetically seal the pores.