JPH0316741B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a small light bulb used for illuminating an instrument panel of an automobile or the like.

Conventionally, a method described in Japanese Patent Publication No. 47-32638 has been developed as a method for manufacturing this type of small light bulb. This method will be explained based on FIGS. 1a to 1h. In other words, this method is
First, a mount consisting of a cylindrical glass bulb 1 with one end closed and the other open, and a filament coil 4 installed between the tips of a pair of lead wires 3, 3 passed through a bead glass 2. Prepare 5 each. The glass bulb 1 is supported vertically with one end facing downward, and the mount 5 is inserted into the glass bulb 1 from the filament coil 4 side, so that the filament coil 4 is brought into contact with one end of the glass bulb 1, that is, the inner surface of the top. Let them come into contact with you. Next, while rotating the glass bulb 1 in a direction around the axis, a portion 6 of the glass bulb 1 to be sealed, which is located closer to the other end opening than the bead glass 2, is heated by burners 7, 7. Then, since the glass bulb 1 is rotating, the portion 6 to be sealed is uniformly heated and softened in the circumferential direction. At this time, by pressing a roller 8 or the like against the outer peripheral surface of the portion 6 to be sealed, this portion is narrowed down to a diameter smaller than the diameter of the bead glass 2 and the bulb 1 as shown in FIG. 1d. The small diameter part 9 has a diameter that does not cause any problem when exhausting the inside. Thereafter, the glass bulb 1 is turned over 180 degrees so that its top is vertically upward, and the exhaust head 10 is hermetically connected to the opening at the other end. In this case, the mount 5 inside the glass bulb 1 is
As the glass bulb 1 is turned over, it falls inside the glass bulb 1 toward the opening at the other end. Then, due to this fall, the bead glass 2 comes into contact with the small diameter part 9,
The mount 5 is positioned within the glass bulb 1. In this state, the inside of the glass bulb 1 is started to be evacuated, and the top side of the glass bulb 1 is hermetically covered with a protective tube 11 connected to the exhaust system. Cover the part on the top side. Next, while rotating the glass bulb 1 again, the portion 6 to be sealed, that is, the small diameter portion 9, is heated and melted by the burners 7, 7, and the small diameter portion 9 and the bead glass 2 in contact with the small diameter portion 9 are mutually bonded. are welded to form a welded portion 16. Subsequently, the inside of the protective cylinder 11 is evacuated, and the portion of the glass bulb 1 on the top side of the small diameter portion 9 is slightly pulled upward, thereby expanding the welded portion 16. After this, when the welded part 16 is hardened, the glass bulb 1 is removed from the head 10 and the protective tube 11, and the welded part 16 is cut, for example, with a cutter, to separate the unnecessary lower part of the glass bulb 1'. By small light bulb 12
is completed.

By the way, in such a manufacturing method, the conventional bead glass 2 has a circular shape that substantially matches the opening shape of the small diameter portion 9 when viewed from the tube axis direction of the bulb 1. For this reason, when the mount 5 is moved to bring the glass bead 2 into contact with the small diameter portion 9, the contact portion continues in the circumferential direction of the small diameter portion 9, as shown in FIG. There will be almost no gap between them. Therefore, the valve 1 shown in FIG. 1e
In the process of evacuating the inside of the glass bulb 1, on the top side of the small diameter portion 9 of the glass bulb 1, that is, in the space where the filament 4 is present, the substantial passage area connected to the exhaust head 10 becomes extremely narrow, making it difficult for gas to escape. Therefore, impure gas remains in the space without being completely exhausted, making it difficult to obtain a desired degree of vacuum. If this happens, not only will the life of the completed light bulb 12 be shortened, but the blackening of the glass bulb 1 will accelerate during lighting, and the tube wall temperature of the glass bulb 1 will increase, which will adversely affect various characteristics of the light bulb 12. There are other problems.

The present invention was made based on the above circumstances, and its purpose is to ensure that gas replacement within the glass bulb is performed reliably and efficiently, to prevent variations and deterioration in quality, and to prevent breakage of glass beads. The present invention aims to provide a method of manufacturing a light bulb that can prevent this.

That is, in order to achieve the above object, the method of the present invention sets the center of gravity of the mount on the side opposite to the filament coil when the position of the center of gravity of the mount is based on the abutting part between the bead glass and the small diameter part, and The cross-sectional shape of the bead glass is approximately circular, and the cross-sectional shape of the bead glass has a large diameter in the direction along the line connecting the pair of lead wires and a small diameter in the direction perpendicular to this line, and the bead glass has a small diameter part. When brought into contact, gaps for gas exchange are formed between the bead glass and the small diameter portion on both sides in a direction perpendicular to a line connecting the lead wires.

According to the present invention, the cross-sectional shape of the bead glass has a large diameter in the direction along the line connecting the pair of lead wires and a small diameter in the direction perpendicular to this line. Since a large amount of wire is secured and the distance between the lead wire and the outer surface of the bead glass is increased, cracking of the bead glass is prevented. Further, when the bead glass is brought into contact with the small diameter part, a pair of gaps for gas exchange are formed between the bead glass and the small diameter part on both sides of the direction perpendicular to the line connecting the lead wires. In addition to the fact that the center of gravity is located on the outer end side of the lead wire, these gaps are symmetrical and have approximately the same size. Therefore, the same amount of air is exhausted from these pair of gaps, so the exhaust It is efficient, and since the center of gravity is located on the outer end side of the lead wire, accurate positioning of the mount is possible.

An embodiment of the method of the present invention will be described below with reference to FIGS. 3 to 6 in addition to the above-described FIGS. 1 a to h.

That is, the procedure for manufacturing a light bulb according to the method of the present invention is basically the same as that of the conventional example described above, but with the following exceptions:
The bead glass 2' passing through the pair of lead wires 3, 3 in an airtight manner is shaped like an ellipse or an ellipse when viewed from the tube axis direction of the glass bulb 1. That is, the bead glass 2' is connected to a line L- connecting the pair of lead wires 3, 3 as shown in FIG.
An ellipse or an ellipse having a large diameter along L and a small diameter in the direction orthogonal to this line L-L, and whose major axis is the line L-L connecting between the lead wires 3, 3. It has a shape similar to that of By doing this, in the process of moving the mount 5 and positioning the mount 5 shown in FIG. As shown, there is a two-point contact state at the ends of the bead glass 2' along the long axis direction. Therefore, bead glass 2′
Gaps 13, 13 as shown in FIGS. 4 and 5 are formed between both sides along the short axis direction of the glass bulb 1 and the opposing inner surface of the small diameter portion 9 to exhaust the inside of the glass bulb 1. In the process, these gaps 1
3 and 13, the exhaust head 10 side and the space where the filament coil 4 is present are communicated with each other. And these gaps 13, 13 are
When the small diameter part 9 is heated again, it is airtightly closed by the melting gap between the small diameter part 9 and the bead glass 2'.
The small diameter portion 9 and bead glass 2' are completely sealed.

On the other hand, the mount 5 connects the filament coil 4 from the bead glass 2' in the lead wires 3, 3.
The portion led out to the opposite side, that is, the external lead wires 14, 14, is extended longer than before, and this allows the center of gravity of the mount 5 to be brought into contact with the bead glass 2' and the small diameter portion 9. When the portions 15, 15 are taken as a reference, the filament coil 4 is deviated to the opposite side. Therefore, when the bead glass 2' is brought into contact with the small diameter portion 9 in the process of positioning the mount 5 shown in FIG. , so that the mount 5 is correctly positioned on the tube axis of the glass bulb 1.

Note that the means for shifting the center of gravity of the mount 5 is not limited to extending the external lead wires 14, 14; for example, the lengths of the external lead wires 14, 14 are the same as before, and a weight is attached to the tips of these wires. You may also attach it.

According to such a manufacturing method, the shape of the bead glass 2' is determined by the line L-- which connects the lead wires 3, 3 when viewed from the tube axis direction of the glass bulb 1.
It has a large diameter along L and a small diameter in the direction orthogonal to this line L-L, that is, an ellipse or a shape close to this with the line L-L connecting between the lead wires 3, 3 as its major axis. Therefore, the pair of lead wires 3, 3 and the bead glass 2' can have a large wall thickness as shown by the dimension l, so that the pair of lead wires 3, 3 are arranged in parallel. Nevertheless, cracks will not occur in the bead glass 2' in this direction. With such an elliptical shape, in the process of bringing the bead glass 2' into contact with the small diameter portion 9, a gap 1 is actively created between them.
3 and 13, the space in the glass bulb 1 where the filament coil 4 is present can be efficiently exhausted through the gaps 13 and 13. Therefore, it is possible to reliably prevent the defective evacuation that has conventionally occurred, and it is possible to achieve a desired degree of vacuum within the glass bulb 1. Therefore, the quality of the light bulb 12 is significantly improved, and a light bulb 12 that is bright, has a long life, and has little blackening of the glass bulb 1 can be provided.

Moreover, since the center of gravity of the mount 5 is shifted to the opposite side of the filament coil 4, when the bead glass 2' is brought into contact with the small diameter part 9, the bead glass 2' Coupled with the point-contact contact, a force acting on the mount 5 to make it perpendicular to the glass bulb 1, that is, a rising force acts on the mount 5. For this reason, the mount 5 is automatically positioned with high accuracy along the tube axis of the glass bulb 1, so there is no risk that the mount 5 will remain collapsed and be sealed to the glass bulb 1, and the bead glass 2' and small diameter The pair of gaps 13, 13 formed between the portions 9 are located symmetrically to each other and have the same size.
The same amount of exhaust gas is emitted from the exhaust gas, improving exhaust efficiency.
Moreover, there is an advantage that the filament coil 4 within the glass bulb 1 can be positioned with high precision by the vertical force acting on the mount 5.

Note that after the inside of the glass bulb is evacuated, a gas may be filled in the glass bulb as necessary.

As detailed above, according to the method of the present invention, the cross-sectional shape of the bead glass is made to have a large diameter in the direction along the line connecting the pair of lead wires and a small diameter in the direction perpendicular to this line. Since the glass thickness in the direction along the line connecting the lead wires is large and the distance between the lead wire and the outer surface of the bead glass is increased, cracking of the bead glass is prevented. Further, when the bead glass is brought into contact with the small diameter part, a pair of gaps for gas exchange are formed between the bead glass and the small diameter part on both sides of the direction perpendicular to the line connecting the lead wires. In combination with the fact that the center of gravity is located on the outer end side of the lead wire, these gaps are symmetrical and have approximately the same size, so the same amount of exhaust air is discharged from these pair of gaps, so the valve The interior can be efficiently exhausted and gas replacement failures can be reliably prevented. This improves the quality of the completed light bulb, making it possible to provide a light bulb that is bright, has a long life, and has less darkening of the bulb. Moreover, by providing the center of gravity of the mount on the outer end side of the lead wire, it is possible to accurately position the mount.

[Brief explanation of the drawing]

1A to 1H are cross-sectional views illustrating the manufacturing process of a light bulb according to a conventional method and an embodiment of the method of the present invention in order of process, and FIG. Figures, Figures 3 to 6
The figures show an embodiment of the method of the present invention, FIG. 3 is a cross-sectional view, FIG. 4 is a cross-sectional view taken along the line - in FIG. 3, and FIG. Figure 6 is a side view of the mount. 1... Glass bulb, 2, 2'... Bead glass, 3... Lead wire, 4... Filament coil, 5... Mount, 6... Part to be sealed, 9...
Small diameter part, 13... gap.

Claims (1)

[Claims] 1. A mount consisting of a filament coil installed between the tips of a pair of lead wires passing through bead glass is inserted into a glass bulb, and the sealing area of the glass bulb is heated. The part to be sealed is narrowed down to a small diameter part, the mount is moved along the axial direction of the glass bulb, and the bead glass is brought into contact with the small diameter part, and the inside of the glass bulb is replaced with gas. In the method of manufacturing a light bulb, the above-mentioned portion to be sealed is heated and softened after the above-mentioned sealing is completed, and the above-mentioned small-diameter portion and the bead glass are welded and bonded, and the above-mentioned mount has its center of gravity based on the abutting portion between the bead glass and the small-diameter portion. In this case, the bead glass is set on the opposite side from the filament coil, and the cross-sectional shape of the small diameter portion is approximately circular, and the cross-sectional shape of the bead glass is set on the opposite side from the filament coil, and the cross-sectional shape of the bead glass is set on the opposite side from the filament coil, and the cross-sectional shape of the bead glass is set on the opposite side from the filament coil. When the bead glass is brought into contact with the small diameter part, there are lines between the bead glass and the small diameter part on both sides in the direction perpendicular to the line connecting the lead wires. A method for manufacturing a light bulb, comprising forming a gap for gas exchange.