KR100729282B1 - Method of manufacturing external electrode fluorescent lamps having various shapes and sizes and glass tube unit structure used for the method - Google Patents

Abstract

According to the present invention, a novel method of manufacturing an external electrode fluorescent lamp is provided. This method includes (a) a glass tube body having both ends open, molded into a shape and size corresponding to the end use of the external electrode fluorescent lamp, and coated with a fluorescent material on the inner wall except for the portion where the external electrode is formed. (B) bonding the second glass tube including the internal electrode for plasma generation to both ends of the glass tube body, and (c) forming the shaft tube narrowing the tube diameter near the junction of the glass tubes. (D) connecting the exhaust pipe to the combination of the glass tube body and the second glass tube; (e) evacuating the interior of the assembly to a certain extent through an exhaust device connected to the exhaust pipe; f) performing a baking operation by generating a plasma in the glass tube through a plasma generator connected to the plasma generating internal electrode; (g) exhausting residual air or foreign matter in the glass tube and injecting a predetermined amount of inert gas into the glass tube, (h) removing the internal electrode and exhaust pipe for plasma generation, and (i) external to the glass tube. Forming an electrode.

Description

METHOD OF MANUFACTURING EXTERNAL ELECTRODE FLUORESCENT LAMPS HAVING VARIOUS SHAPES AND SIZES AND GLASS TUBE UNIT STRUCTURE USED FOR THE METHOD}

1 is a flowchart illustrating a manufacturing process of an external electrode fluorescent lamp according to an exemplary embodiment of the present invention.

2 is a view schematically showing each manufacturing process of the external electrode fluorescent lamp manufacturing process according to an embodiment of the present invention.

3 is a view schematically illustrating a process of manufacturing an external electrode fluorescent lamp according to another exemplary embodiment of the present invention.

4 is a flowchart illustrating a manufacturing process of an external electrode fluorescent lamp according to another embodiment of the present invention.

FIG. 5 is a view illustrating a process of manufacturing an external electrode fluorescent lamp using a glass tube of a unitized structure including an internal electrode for plasma generation according to an embodiment of the present invention.

6 is a view illustrating a process of manufacturing an external electrode fluorescent lamp using a glass tube having a unitized structure including an internal electrode for plasma generation according to another exemplary embodiment of the present invention.

FIG. 7 illustrates one exemplary structure of a glass tube of unitary structure including an internal electrode and an exhaust pipe for plasma generation.

FIG. 8 shows another exemplary structure of a glass tube having a unitary structure including an internal electrode and an exhaust pipe for generating plasma.

9 is a view schematically showing an example in which the present invention is applied to an external electrode fluorescent lamp of a predetermined shape.

<Explanation of symbols for the main parts of the drawings>

10: coated glass tube

22: internal electrode for plasma generation

24: lead line

30: exhaust pipe

40: external electrode

400, 600: glass tube of unit structure

P: vacuum pump

The present invention relates to a method of manufacturing a fluorescent lamp, more specifically an external electrode fluorescent lamp (EEFL) having various shapes and sizes.

The external electrode fluorescent lamp is a gas discharge operation without enclosing the gas in a sealed glass tube and forming electrodes on both ends of the lamp to expose the electrode to the gas discharge space, thereby generating plasma in the lamp by the electric field of the external electrode. It is a fluorescent lamp having a structure. The gas discharge phenomenon inside the tube is the same as that of a normal lamp, but since the glass tube itself acts as a dielectric, the wall gain due to the accumulation of space charges caused by the discharge is added to the external voltage applied to induce the discharge. This will occur.

Unlike ordinary fluorescent lamps, external electrode fluorescent lamps have electrodes outside the lamps and do not generate heat by using an electron emission method by electric fields.The lamps have a lifespan of more than five times longer than ordinary fluorescent lamps and 10 times more brightness. It is a large, next-generation lighting lamp with five times more energy efficiency than a cold cathode fluorescent lamp (CFFL). In addition, the external electrode fluorescent lamp has a number of advantages, such as the driving of a plurality of pipes with other driving devices, and is widely used in applications requiring high brightness, such as LCD TVs and billboards.

On the other hand, during the manufacturing of the EEFL, a baking process is performed as a process of removing impurities, moisture, and other foreign matter in the powder, which is usually performed using a heater box.

Such a heater box is useful for manufacturing a standardized external electrode fluorescent lamp, but as the use of external electrode fluorescent lamps is diversified, a problem arises. In other words, the external electrode fluorescent lamps are not only used in LCD, but also used in various forms of billboards. Due to their characteristics, the billboards are not fixed in shape. Correspondingly, external electrode fluorescent lamps should be manufactured in various shapes and sizes.

However, the heater box is adapted for the continuous mass production of external electrode fluorescent lamps, such as linear fluorescent lamps, of a particular shape and size, and performs two baking operations. That is, for example, impurities in the powder are firstly removed at a high temperature of 600 to 700 ° C., and residual air, foreign matter, moisture, etc. are also removed in the second baking operation. By the way, the external electrode fluorescent lamps used in billboards and the like vary in their shapes and sizes and are often curved. In this case, if the glass tube for the external electrode fluorescent lamp is not precisely formed in the same thickness, the thin part is recessed or totally lower than the temperature in the first baking process, but in the second baking operation at a certain high temperature. If the problem arises that the shape may be distorted, and once the glass tube enters the heater box, the baking operation for the lamp cannot be seen from the outside, and it is difficult to prevent the problem, and in fact, the baking operation is performed with precise control. You will not be able to perform Therefore, it is difficult for the operator to control the glass tube once entered into the heater box. Therefore, before putting the glass tube into the heater box, it is necessary to work with a considerable burden of precisely forming a glass tube of any shape with a certain thickness. .

In addition, since the size of the heater box is fixed rather than variable, it can only process a glass tube that can fit into a heater box of a predetermined size, and the outside of which is larger in size than the size of the heater box depending on the application such as a billboard. When manufacturing an electrode fluorescent lamp, the heater box cannot be used. Therefore, the heater box must be provided separately for the manufacture of an external electrode fluorescent lamp of a desired shape and size, or the size of the external electrode fluorescent lamp is limited to the size of the heater box. There are problems such as being forced to produce according to. Therefore, there is a limit to manufacturing a single lamp of a desired size, which in turn causes a rise in the manufacturing cost of the fluorescent lamp.

In addition, there is an attempt to manufacture an external electrode fluorescent lamp using plasma without using a heater box, but this method has the following fatal disadvantage.

That is, both the apparatus and the method for performing a baking operation using plasma are configured to manufacture a linear external electrode fluorescent lamp like a normal fluorescent lamp, and thus it is difficult to manufacture EEFLs of various shapes and sizes used for signboard production. Do.

In addition, according to this prior art, the operation of removing the glass tube including the internal electrode for the plasma generation from the EEFL glass tube body using a high temperature heat such as a torch, which is to be expanded and contracted at the junction of the two glass tubes This is a phenomenon that the glass is recessed to the inside of the EEFL glass tube body is repeated, there is a problem that must pay attention to the removal operation due to the large pressure difference inside and outside the glass tube when removing the glass tube. The shape and thickness of the recessed portion is not constant, which has a fatal adverse effect on the durability of the EEFL, and it is accompanied by a lot of difficulties in removing traces of the recessed portion, and requires high skill. As the diameter of the EEFL glass tube body increases, the above-mentioned disadvantages also increase. Therefore, the current state of the art has not been commercialized.

Therefore, in the present invention, in manufacturing an external electrode fluorescent lamp having various shapes and sizes, the operator can easily manufacture the external electrode fluorescent lamp regardless of the shape or size of the fluorescent lamp, and the shape and size of each lamp It is an object of the present invention to provide a method for manufacturing an external electrode fluorescent lamp without employing each heater box correspondingly.

In addition, in the manufacture of a fluorescent lamp, in particular an external electrode fluorescent lamp, as described above, not only a heater box, but also a glass tube including an inner electrode for plasma generation for baking the lamp as a single Another object is to provide a unit in the form of a simple production of the lamp.

Still another object of the present invention is to manufacture an EEFL using plasma without a heater box, and when removing a glass tube from an EEFL glass tube body, which can produce an EEFL having various sizes and shapes and includes an internal electrode for plasma generation. It is an object of the present invention to provide a method for producing an EEFL without significantly affecting the shape, thickness and appearance of the glass tube body.

In order to achieve the above object, the present inventor studies a replacement means that can replace a heater box, and performs a baking operation using a plasma principle instead of a baking process using a conventional heater box. The present invention was completed to provide an external electrode fluorescent lamp using existing equipment without providing new equipment.

That is, according to the present invention for achieving the above object, there is provided a novel external electrode fluorescent lamp manufacturing method, which (a) is open at both ends, the shape corresponding to the end use of the external electrode fluorescent lamp and Providing a glass tube body which is molded to a size and whose inner wall portion is coated with a fluorescent material except for a portion where an external electrode is formed, and (b) a second glass tube including an inner electrode for plasma generation is provided. Bonding to both ends of (c), (c) performing shaft forming to narrow the tube diameter near the joining portion of the glass tubes, and (d) connecting an exhaust pipe to a combination of the glass tube body and the second glass tube; (e) evacuating the interior of the assembly to a certain extent through an exhaust device connected to the exhaust pipe, and (f) connecting to the internal electrode for plasma generation Generating a plasma in the glass tube through a plasma generating apparatus to perform baking operation; (g) exhausting remaining air or foreign matter in the glass tube and injecting a predetermined amount of inert gas into the glass tube; h) removing the inner electrode and the exhaust pipe for plasma generation, and (i) forming an outer electrode in the glass tube.

Therefore, according to the present invention, since the plasma generating apparatus connected to the internal electrode for plasma generation is operated inside the glass tube, plasma is formed, and by using the plasma to burn impurities and other foreign substances in the powder inside the glass tube and exhaust them, Unlike the prior art, a single baking operation can remove impurities and other foreign matter in the powder, and replaces the existing heater box. After all, no need to employ a heater box, even if the external electrode fluorescent lamp of any shape and size, it is possible to remove impurities in the glass tube by using the plasma principle, the internal electrode for the plasma generation after this operation By removing and only forming the external electrode in the glass tube according to a conventional external electrode fluorescent lamp manufacturing process, it is possible to manufacture an external electrode fluorescent lamp of the desired size and shape. In addition, by carrying out shaft tube molding to reduce the diameter of the glass tube, it is possible to prevent the phenomenon of the glass tube caused by the pressure difference between the inside and the outside of the glass tube during the separation operation of the glass tube later.

According to the exemplary embodiment of the present invention, the inner wall of the second glass tube may not be coated with a fluorescent material, or the inner wall of the second glass tube may be coated with a fluorescent material except for the bonding portion with the glass tube body.

According to one embodiment of the invention, the second glass tube is bonded to one end of the glass tube including the inner electrode for plasma generation to one end of the glass tube body, the air through the other side of the glass tube body to form a hole Next, the exhaust pipe may be connected to both ends of the glass tube body in such a manner that the glass tube including the remaining inner electrode for plasma generation is bonded to the other side of the glass tube body.

Preferably, the exhaust pipe may be connected to the second glass tube near the position where the internal electrode for plasma generation is located.

According to one preferred embodiment of the present invention, the exhaust pipe and the internal electrode for plasma generation may be simultaneously removed from the glass tube body by cutting the shaft tube forming part.

According to another embodiment of the present invention, there is provided a method of manufacturing an external electrode fluorescent lamp, which (a) is open at both ends, and is molded in a shape and size corresponding to the use of the external electrode fluorescent lamp; Providing a glass tube body coated with a fluorescent material on an inner wall except for a part of the inner wall near both ends, and (b) bonding a pair of second glass tubes having one end closed to each end of the glass tube body, respectively, Bending through parallel to the main body, and (c) a pair of third glass tubes containing an inner electrode for plasma generation, the third glass tube including a connecting portion having a diameter smaller than the diameter of the glass tube through the connecting portion; Connecting to the second glass tube in a vertical relationship with each other so as to communicate with the second glass tube; and (d) any one of the pair of third glass tubes Connecting an exhaust pipe to the vacuum chamber to vacuum the inside of the connected glass tube to a certain limit, and (e) generating a plasma inside the glass tube through a plasma generating apparatus connected to the plasma generating inner electrode to perform a baking operation. (F) exhausting residual air or foreign matter in the glass tube, (g) injecting a predetermined amount of inert gas into the glass tube through the exhaust pipe, and (h) the internal electrode for plasma generation And removing the third glass tube and the exhaust pipe comprising a.

According to one embodiment of the invention, the method may further comprise the step of forming an external electrode on the surface of the second glass tube subsequent to step (h).

According to a preferred embodiment, the second glass tube may include an external electrode on its surface.

According to another embodiment of the present invention there is provided a method of manufacturing an external electrode fluorescent lamp, which method (a) is open at both ends, and molded into a shape and size corresponding to the use of the external electrode fluorescent lamp; Providing a glass tube body coated with a fluorescent material on an inner wall except for a part of the inner wall near both ends, and (b) bonding a pair of second glass tubes having one end closed to each end of the glass tube body, respectively, Bending and forming parallel to the main body, and (c) third and fourth glass tubes containing internal electrodes for plasma generation, the third and fourth glass tubes including connecting portions having a first diameter smaller than the diameter of the glass tubes. Connecting to the uncoated glass tube in a vertical relationship through the connecting portion to communicate with the uncoated glass tube, and (d) an exhaust pipe to the third glass tube. By connecting to the vacuum, the interior of the bonded glass tube body and the second glass tube to a certain limit, (e) by generating a plasma inside the glass tube through a plasma generating device connected to the internal electrode for plasma generation Performing a baking operation, (f) evacuating remaining air or foreign matter in the glass tube, (g) injecting a predetermined amount of inert gas into the glass tube primarily through the exhaust pipe; and (h) Removing the fourth glass tube not connected to the exhaust pipe from the second glass tube, and reducing the connecting portion of the third glass tube to a second diameter smaller than the first diameter; and (i) reducing the inert gas of the lamp. Evacuating leaving only the amount for discharge, and (j) removing the third glass tube from the second glass tube.

According to a preferred embodiment, in the step (g), the pressure inside the glass tube may be introduced with an inert gas that is several Torr smaller than atmospheric pressure.

Preferably, the step (i) may further include the step of completely exhausting the inert gas, and injecting a predetermined amount of the inert gas secondly for discharging the lamp.

According to another embodiment of the present invention there is provided a method for manufacturing an external electrode fluorescent lamp, which method (a) is open at both ends, molded in a shape and size corresponding to the use of the external electrode fluorescent lamp, the both ends Providing a glass tube body coated with a fluorescent material on an inner wall except for a portion of the inner wall nearby, and (b) a second glass tube containing an inner electrode for plasma generation, the connecting portion having a first diameter smaller than the diameter of the glass tube; And a glass tube of the first and second unit structures, each of which is vertically connected such that a glass tube to be closed and a third glass tube of which one end is closed are connected to each other via the connecting portion, respectively, are respectively connected to both ends of the glass tube body, and then parallel to the glass tube body. (B) connecting an exhaust pipe to one glass tube of the second glass tube, and forming an inner portion of the laminated glass tube. Vacuuming the part to a certain limit, (d) generating a plasma in the glass tube through a plasma generator connected to the plasma generating internal electrode to perform baking operation, and (e) remaining air in the glass tube Exhausting the foreign matter, (f) injecting a predetermined amount of inert gas into the glass tube primarily through the exhaust pipe, and (g) a second glass tube to which the exhaust pipe is not connected; Removing from the second tube and reducing the connecting portion of the second glass tube to which the exhaust pipe is connected to a second diameter smaller than the first diameter; and (h) evacuating the inert gas, leaving only the amount for discharging the lamp; i) removing the glass tube to which the exhaust pipe is connected from the uncoated glass tube.

According to one embodiment of the invention, the method may further comprise the step of forming an external electrode on the surface of the third glass tube following step (i).

According to a preferred embodiment, the third glass tube may include an external electrode on its surface.

According to another embodiment of the present invention there is provided a method for manufacturing an external electrode fluorescent lamp, which method (a) is open at both ends, molded in a shape and size corresponding to the use of the external electrode fluorescent lamp, the both ends Providing a glass tube body coated with a fluorescent material on an inner wall except for a portion of the inner wall nearby, and (b) a unit comprising a first glass tube section including an inner electrode for plasma generation and a second glass tube section bonded to the glass tube body Bonding a glass tube having a structure to both ends of the coated glass tube body, and (c) connecting an exhaust pipe to one glass tube of the glass tube including the internal electrode, and vacuuming the interior of the laminated glass tube to a certain limit. And (d) plasma inside the laminated glass tube through a plasma generator connected to the internal electrode for plasma generation. Generating a baking step, (e) exhausting remaining air or foreign matter in the glass tube and injecting a predetermined amount of inert gas into the glass tube, and (f) a first glass tube including the internal electrode. Removing the section and the exhaust duct.

Preferably, between the first glass tube section and the second glass tube section, the tube can be shaped such that the diameter of the tube is narrow.

According to one preferred embodiment, the shaft tube forming part may be cut to remove the first glass tube section.

The exhaust pipe is preferably connected to the first glass tube section.

According to another embodiment of the present invention, a method of manufacturing an external electrode fluorescent lamp is provided, which method comprises (a) a glass tube molded into a shape and size corresponding to the use of the external electrode fluorescent lamp, and whose inner wall is coated with a fluorescent material. Providing a main body, (b) a glass tube having a unit structure comprising a first glass tube section including an internal electrode for plasma generation, a second glass tube section bonded to the coated glass tube body, and a third glass tube section serving as an exhaust pipe; Arranging side by side with the coated glass tube body, and then joining the second glass tube sections near both ends of the coated glass tube body, and (c) through the exhaust device connected to the third glass tube section, Evacuating the interior of the glass tube and the coated glass tube body having a predetermined unit structure to a certain limit, and (d) Generating a plasma inside the glass tube through a plasma generating device connected to the substrate to perform a baking operation; (e) removing the first glass tube section; and (f) exhausting remaining air or foreign matter in the glass tube and Injecting a predetermined amount of inert gas therein, and (g) removing the third glass tube section.

Preferably, the shaft tube is formed so that the diameter of the tube is narrowed between the first glass tube section and the second glass tube section, and between the second glass tube section and the third glass tube section.

According to a preferred embodiment, the diameter of the shaft tube forming portion between the first glass tube section and the second glass tube section is larger than the diameter of the shaft tube forming portion between the second glass tube section and the third glass tube section.

According to another aspect of the invention there is provided a glass tube of unit structure connected to a fluorescent substance coated glass tube for an external electrode fluorescent lamp, which glass tube is connected to the fluorescent substance coated glass tube and then generates plasma therein. A first glass tube section including an internal electrode for generation and an exhaust pipe for evacuating the inside of the fluorescent substance coated glass tube, removing impurities, foreign substances, etc. in the fluorescent substance and injecting an inert gas, and communicating with the fluorescent substance coated glass tube And a second glass tube section interconnected, wherein the first glass tube section and the second glass tube section are axially shaped to narrow the tube diameter.

According to yet another aspect of the present invention there is provided a glass tube of unit structure connected to a fluorescent substance coated glass tube for an external electrode fluorescent lamp, which glass tube is connected to the fluorescent substance coated glass tube and then generates plasma therein. A first glass tube section including an inner electrode for generation, a second glass tube section interconnected to communicate with the fluorescent substance coated glass tube, and an interior of the fluorescent substance coated glass tube, and vacuuming the inside of the fluorescent substance to remove impurities, foreign substances, etc. It consists of a third glass tube section that serves as an exhaust pipe for injecting, and between the first glass tube section and the second glass tube section, and between the second glass tube section and the third glass tube section is characterized in that the shaft is formed to narrow the tube diameter It is done.

According to an embodiment of the present invention, an external electrode may be formed on the surface of the second glass tube section during the manufacturing process of the external electrode fluorescent lamp.

Preferably, the second glass tube section includes external electrodes on its surface.

Preferably, the diameter of the shaft tube forming portion between the first glass tube section and the second glass tube section is larger than the diameter of the shaft tube forming portion between the second glass tube section and the third glass tube section.

The objects, features and advantages of the present invention described above will be more clearly understood through the following detailed description of preferred embodiments of the present invention with reference to the accompanying drawings.

In the following description with reference to the accompanying drawings, in the manufacture of an external electrode fluorescent lamp, a description of the manufacturing process, operations that can be commonly performed, and the configuration or operation of a known device, which are already known in the art, Omit. In addition, although the characteristic configuration of the present invention has been described and illustrated as being applied to an external electrode fluorescent lamp, it will be readily understood by those skilled in the art that the present invention can also be applied to neon signs using glass lamps that are not coated with a fluorescent material.

1. First embodiment

1 is a view briefly showing a manufacturing process of a novel external electrode fluorescent lamp according to an embodiment of the present invention in the form of a flow chart, and FIG. Hereinafter, a first preferred embodiment of the present invention will be described with reference to FIGS. 1 and 2.

1-1. Coated glass tube body

First, a glass tube for preparing an external electrode fluorescent lamp is prepared. In FIG. 2, a glass tube having a straight tube shape is illustrated for convenience. However, the glass tube is formed in a desired shape and size in advance for a use in which an external electrode fluorescent lamp is used. , The fluorescent material is coated on the inner surface of the glass tube in accordance with a process commonly performed in the general fluorescent lamp manufacturing process (Fig. 2 (a)). Although the figure shows that the fluorescent material is coated on the entire inner wall of the glass tube for convenience, it will be readily understood by those skilled in the art that the fluorescent material may not be coated on the part in consideration of the site where the external electrode is formed later. Before the coating of the fluorescent substance, an operation of cleaning foreign substances on the inner surface of the glass tube is usually performed. The coated glass tube 10 thus prepared is introduced into the manufacturing process (S101).

1-2. Internal electrode and exhaust pipe connection and shaft pipe forming for plasma generation

The second glass tube 20 including the inner electrode 22 for plasma generation is connected to the coated glass tube 10 prepared through the above process (S102). In connecting the glass tubes 10 and 20, for example, a torch is applied to the coated glass tube 10 having the shape as shown in FIG. 2, and the internal electrode 22 for plasma generation having the lead line 24 connected thereto. The 2nd glass tube 20 which contains this is connected. According to a preferred embodiment of the present invention, a hole is formed in the vicinity of a position where the inner electrode 22 is formed and a position at which the outer electrode 40 is to be formed later, and the exhaust pipe 30 is connected (S103). As will be readily appreciated by those skilled in the art, it should be noted that the steps S102 and S103 may be performed in a different order depending on the position of the connection to the glass tube of the exhaust pipe. That is, when the exhaust pipe 30 is connected to the coated glass tube 10, before the second glass tube 20 including the plasma generating inner electrode 22 is connected to the coated glass tube 10, the exhaust pipe 30 is connected to the coated glass tube 10. 30 may be connected to the coated glass tube 10.

The internal electrode 22 for plasma generation is connected to a plasma generator (not shown) via the lead line 34. When the device is driven, plasma is generated inside the glass tube coupled through the internal electrode. do. Since the configuration of the plasma generating device and the internal electrode for plasma generation, the plasma generating operation, and the like are already known in the art, a detailed description thereof will be omitted, and it should be noted that the configuration of the internal electrode is shown for simplicity.

According to one preferred embodiment of the present invention, by using a torch at one end of the coated glass tube 10 to connect the second glass tube 20 including the electrode for plasma generation, the other side of the coated glass tube 10 Air is blown through to form a hole in a predetermined portion, the exhaust pipe 24 is connected to the hole, and then the second glass tube 20 including the remaining plasma generating electrode on the other side of the coated glass tube 10 is opened. Connect. The state in which the electrode and the exhaust pipe are connected to the glass tube is shown in FIGS. 2B and 2C. The inner electrode for plasma generation is not necessary in the outer electrode fluorescent lamp and is removed. According to a preferred embodiment, the exhaust pipe is provided at the portion of the inner electrode 22 for plasma generation so that the exhaust pipe can also be removed during this removal operation. .

However, depending on the diameter of the glass tube, it may be difficult to remove the internal electrode and the exhaust pipe. That is, when the diameter of the glass tube is large, when the bonding portion of the second glass tube 20 and the coated glass tube 10 including the inner electrode is separated by using a torch, due to the pressure difference inside and outside the glass tube, The coated glass tube in the area is depressed inside and deteriorates in appearance, and a precise finishing operation for trimming it is required. In view of this point, according to one preferred embodiment of the present invention, as shown in FIG. 2D, a forming molding (shaft tube molding) for narrowing a pipe diameter of a part of the glass tube 10 is performed. By doing so, the glass tube separation operation is made easier later. On the other hand, when forming the forming while the exhaust pipe is connected, it may be difficult to perform the forming or the complicated forming due to the exhaust pipe, it is preferable to perform the forming before connecting the exhaust pipe to one end of the glass tube .

1-3. Vacuuming and Baking Operations

As described above, after the operation of connecting the second glass tube 20 including the internal electrode 22 and the exhaust pipe 30 to the coated glass tube 10 is performed, the vacuum pump to which the exhaust pipe 30 is connected is performed. Operation (P) is performed to vacuum the inside of the glass tube to a certain limit through which a current can flow (S104). Thereafter, when both ends of the internal electrode for plasma generation are connected to the plasma generating device, and the inside of the glass tube is discharged by applying a high current and a high voltage, for example, electrons are emitted in the plasma state inside the glass tube. Therefore, not only the impurities and other foreign matters in the powder inside the glass tube are burned due to the generated plasma, but also the vacuum is also increased (S105). As described above, according to the present invention, unlike the prior art in which the heater box is used to remove impurities or other foreign matters in the powder inside the glass tube and to facilitate the exhaust, each of the external electrode fluorescent lamps having various shapes and sizes can be used. Without providing a heater box according to the shape or size of the, it is possible to perform the baking operation in a single operation using the plasma method.

1-4. Inert gas introduction and removal work

Meanwhile, after the baking operation, the residual air and the material removed through the baking operation are evacuated to increase the degree of vacuum, and then a certain amount of inert gas is injected thereafter for discharging the external electrode fluorescent lamp (S106).

Subsequently, the exhaust pipe 24 is removed, and the inner electrode 22 fulfills a predetermined purpose of baking a glass tube and is not necessary in the outer electrode fluorescent lamp, so that the inner electrode is removed, that is, including the inner electrode. The second glass tube 20 is cut out (S107). This removal is usually done using a torch.

When the exhaust pipe 30 is connected to the glass tube in the vicinity of the portion of the internal electrode 22 as shown in FIG. 2 (d), the second glass tube 20 including the internal electrode is cut out using a torch. By doing so, the internal electrode 22 and the exhaust pipe 30 can be removed at one time, or the exhaust pipe 30 and the internal electrode 22 can be removed separately according to the connection position.

1-5. External electrode formation

After removing the internal electrode and the exhaust pipe, an external electrode 40 is formed in the vicinity of a portion where the internal electrode and the exhaust pipe for plasma generation are formed (S108). An external electrode fluorescent lamp in which the external electrode 40 is formed is shown at 50 in e.

2. Second Embodiment

3 is a view schematically showing a second preferred embodiment of the present invention. In the following description, the description of the configuration or manufacturing process overlapping with the first embodiment will be omitted.

First, both ends are open, and a glass tube molded into a shape and size corresponding to the end use of the external electrode fluorescent lamp is prepared. As shown, the glass tube 100 is coated with a fluorescent material inside thereof except for a part of both ends for easy bonding with a separate glass tube described below.

Subsequently, after bonding a pair of uncoated second glass tubes 200 having one end closed to each end of the coated glass tube, the uncoated second glass tube 200 is bent to be parallel to the coated glass tube 100. do. That is, an external electrode is formed later on the uncoated second glass tube. When the external electrode forming portion is formed in a straight line continuous with the coated glass tube, the overall size of the lamp is increased, and the external electrode forming portion emits light. Since it is not supported, shadows are created. Therefore, in consideration of this point, it is preferable to bend the external electrode forming part to be parallel to the coated glass tube 100. In addition, although the inner wall of the second glass tube 200 is not coated with a fluorescent material, it should be noted that in some embodiments, the fluorescent material may be coated on the inner wall portion except for the bonding portion with the glass tube 100. This also applies to other embodiments.

Next, the third glass tube 300 including the plasma generation inner electrode 340 to which the lead line 320 is connected is bonded to communicate with the second glass tube 200. At this time, rather than directly connecting the third glass tube 300 and the second glass tube 200, the bonding is performed through the connecting portion 360 having a small diameter. That is, the third glass tube 300 including the internal electrode for plasma generation should be removed after achieving the predetermined purpose of baking. However, as described above, the glass tube 300 is conventionally bonded to the open end of the coated glass tube and then used to remove the bonding portion by torch heating, and the like. It inevitably occurs, and therefore, the end of the coated glass tube has to be reworked, and this operation requires a high degree of skill and has a problem such as that, the larger the diameter, the more the problem also increases. The first embodiment of the present invention solves this problem through the above-mentioned forming molding, and in the second embodiment of the present invention, a glass tube including an internal electrode for plasma generation is directly bonded to the open end of the external electrode fluorescent lamp. Instead, a method of connecting the glass tube in which the external electrode is formed in a vertical relationship is adopted. That is, as shown in FIG. 3, the third glass tube 300 is connected to the non-coated glass tube 200 in a vertical relationship, and in this case, the glass tube 300 has a connection portion 360 having a diameter smaller than that of the glass tube. Is provided, the glass tube 300 and the glass tube 200 is connected through the connection in communication. Therefore, when the glass tube 300 is removed after the baking operation, only a small diameter connection part 360 may be cut, and thus the removal operation may be easily performed while preventing the depression of the glass tube.

Next, although not shown in the drawing, a step of evacuating the inside of the glass tube to a certain limit by connecting an exhaust pipe to a predetermined portion of one of the third glass tubes 300 including the internal electrode. Subsequently, a baking operation is performed on the inside of the glass tube through a plasma generating device, exhausting residual air or foreign matter, injecting an inert gas, removing the third glass tube 300 and the exhaust pipe, and no coating. Through the operation of forming the external electrode on the glass tube 200, the external electrode fluorescent lamp of the desired shape and size is finally completed.

On the other hand, according to another preferred embodiment of the present invention, a means for facilitating the removal of the glass tube and the exhaust pipe including the internal electrode is provided. Specifically, when performing the operation of generating the plasma and the operation of generating the inside of the glass tube, the force of the glass tube withstanding such operation is different. That is, since a considerable high heat is generated during the baking operation using the plasma, the diameter of the glass tube may be configured to a smaller diameter compared to the baking operation using the plasma when performing the exhaust operation. In addition, since the inside of the glass tube is considerably vacuumed during the plasma operation, although the diameter of the connecting portion 360 of the glass tube is smaller than that of the third glass tube 300 as in the above embodiment, it is able to withstand the baking process using the plasma. Because there must be, there is a limit to reducing the diameter. Therefore, since the connection portion 360 has a considerable diameter, it may be difficult to remove the connection portion 360 during the removal operation of the glass tube 300 and the third glass tube in detail in consideration of the problem of glass tube depression due to the difference in the pressure inside and outside the glass tube. (300) The removal shall be performed. Therefore, according to the present embodiment, the diameter of the connecting portion 360 is smaller than the diameter of the third glass tube 300, while the glass tube is easily removed and the diameter is sufficient to withstand the plasma operation. Introduce processes to alleviate the difficulties of removal operations.

Specifically, after performing the baking operation using the plasma to exhaust the remaining air or foreign matter in the glass tube, a predetermined amount of inert gas is first injected into the glass tube. Preferably, the inside of the glass tube is injected with an inert gas that is several Torr smaller than atmospheric pressure to minimize the pressure difference inside and outside the glass tube as much as possible. Subsequently, the glass tube including only the internal electrode for plasma generation and to which the exhaust pipe is not connected is removed from the second glass tube 200. At this time, since the pressure difference between the inside and the outside of the glass tube is reduced as much as possible, the glass tube including the inner electrode can be easily removed. Next, the diameter of the connecting portion 360 of the third glass tube 300 to which the exhaust pipe is connected is processed using a torch to have a diameter smaller than the original diameter. Subsequently, the injected inert gas may be exhausted through the exhaust pipe, leaving only the amount for discharge, and the remaining third glass tube 300 including the internal electrode may be removed from the second glass tube 200. As such, according to the present exemplary embodiment, the glass tube including the inner electrode is removed in two stages. The pressure difference in the glass tube is reduced to easily remove only one glass tube first, and then connect the remaining portion of the glass tube 360. By further reducing the diameter of) the removal of the glass tube is also facilitated. Meanwhile, the exhaust operation of the inert gas may be performed by completely exhausting the inert gas in order to completely remove foreign substances, and then injecting an inert gas for lamp discharge in a second manner.

Finally, an external electrode is formed on the second glass tube 200. Meanwhile, according to the exemplary embodiment of the present invention, the external electrode may be formed in the second glass tube in advance to simplify the manufacturing process. That is, after coating the surface of the second glass tube with carbon, silver paste or the like to dry the portion and then heat-treating or taping the aluminum tape or the like to prepare a second glass tube in which the external electrode is formed in advance, and then The manufacturing process may also be carried out, as is the case in other embodiments.

3. Third embodiment

According to the first and second embodiments, a glass tube including an inner electrode and a glass tube including an inner electrode is provided through separate operations. However, according to the present embodiment, the manufacturing process is further simplified by directly bonding the glass tube of the unit structure including the site where the external electrode is to be formed to the coated glass tube, and FIG. 4 illustrates this embodiment of the present invention in the form of a flowchart. Is showing. As shown in FIG. 4, the present embodiment is generally similar to the embodiment shown in FIG. 1 except for providing and removing the glass tube of the unit structure. Therefore, description of each step of the manufacturing process overlapping with that shown in FIG. 1 is omitted.

As illustrated in FIG. 5, a second glass tube 440 including a first glass tube 420 having one end closed and an internal electrode 444 to which the lead line 442 is connected is connected to the second glass tube 440 through the connecting portion 446. 1 is connected to both ends of the coated glass tube body 500 of the glass tube 400 of the unit structure connected vertically connected to the glass tube 420 and communicate with each other. Therefore, in the manufacturing process of the external electrode fluorescent lamp, a glass tube in which the external electrode is formed and a glass tube including the internal electrode may be separately provided to simplify the process of bonding each other, and the glass tube required for manufacturing the external electrode fluorescent lamp may be unit Since the mass production can be provided in units, the manufacturing process can be performed more efficiently. Other manufacturing processes except providing the glass tube 440 including the inner electrode and the glass tube 420 on which the outer electrode is to be formed as the glass tube 400 of the unit structure and bonding them to the coated glass tube body 500 are described above. Since it can be performed in the same way as, detailed description thereof will be omitted. Meanwhile, although not specifically illustrated in the drawings, it should be noted that the glass tube of the unit structure may be provided as a unit structure including an exhaust pipe. In this case, the exhaust pipe is provided integrally with any part of the second glass tube 440. Alternatively, the exhaust pipe may be connected to any portion of the second glass tube 440 through a separate operation.

4. Fourth Example

According to the above-described embodiment, the glass tube including the inner electrode is vertically connected to the glass tube in which the outer electrode is formed through the connecting portion, thereby facilitating the unnecessary removal of the glass tube later. However, according to this embodiment, a means for easily performing the glass tube removing operation is provided without providing a glass tube including a narrow tube diameter connecting portion.

Specifically, as shown in FIG. 6, according to one preferred embodiment of the present invention, the glass tube 600 including the inner electrode 640 to which the lead line 620 is connected is connected to the open end of the coated glass tube 700. Joined and communicated. The glass tube 600 has a unit structure including a first glass tube section 660 containing an internal electrode for plasma generation and a second glass tube section 680 bonded to an open end of the coated glass tube 700. As shown in the figure, the first glass tube section 660 and the second glass tube section 680 are continuous through the formed portion 690 so that the diameter between them is narrow. Therefore, in the future, the external electrode fluorescent lamp may easily cut the first glass tube section 660 including the internal electrode for plasma generation, and the like, without the depression of the glass tube. After the glass tube 600 of such a unit structure is bonded to each open end of the coated glass tube 700, an external electrode fluorescent lamp can be manufactured through the same process as described in connection with the first to third embodiments. Although not shown in FIG. 6, the exhaust pipe may be connected anywhere in the first glass tube section 660, so that it can be removed together with the first glass tube section 660 later in one removal operation, in advance. It may be connected to 600 and provided in a unit structure (see FIG. 7).

On the other hand, according to another preferred embodiment of the present invention, the same effect is provided in a simple unit structure without providing a separate exhaust pipe. That is, as illustrated in FIG. 8A, unlike the illustrated in FIG. 7, the glass tube 800 having a unit structure bonded to the coated glass tube 700 is divided into three parts. That is, the glass tube 800 includes a first glass tube section 820, a second glass tube section 840, and a third glass tube section 860. The first glass tube section 820 includes an inner electrode 824 for plasma generation having a lead line 822 connected thereto, and the second glass tube section 840 is a portion to be bonded to the coated glass tube 700 to form an external electrode later. The third glass tube section 860 serves as an exhaust pipe and is connected to an external vacuum pump P. Between the first glass tube section 820 and the second glass tube section 840, between the second glass tube section 840 and the third glass tube section 860 is also formed to form a narrow tube diameter. In this case, unlike the exhaust operation, since the glass tube may be deformed by applying more heat to the glass tube when the plasma is generated, the forming part between the first glass tube section 820 and the second glass tube section 840 may include the second glass tube section 840. It is preferable to mold the diameter larger than the forming molded portion between the third glass tube section 860. According to an embodiment of the present invention, the glass tube 800 having such a structure is bonded to the coated glass tube 700 as shown in FIG. When the glass tube section 820 is removed, the third glass tube section 860 is removed after performing the vacuuming operation, the injection of the inert gas, and the like through the third glass tube section 860, only the second glass tube section 840 is removed. It remains to be bonded to the coated glass tube 700, and the external electrode may be formed in the second glass tube section.

6. Application examples of the present invention

FIG. 9 schematically shows an example of providing an external electrode fluorescent lamp of a signboard using, for example, the letter 'not' (excluding 'o'). According to the prior art, there is a burden of separately providing a heater box corresponding to this shape and size and maintaining a constant glass tube shape, but according to the present invention, without using a heater box, the glass tube is simply formed in the shape. When plasma is generated inside the glass tube by connecting the internal electrode and the exhaust pipe for plasma generation and operating the plasma generator connected to these electrodes, other impurities except fluorescent materials are burned, and after the exhaust process is completed, the internal electrodes and exhaust pipe installed By removing and ultimately forming the external electrode through a conventional operation, an external electrode fluorescent lamp of a desired shape and size can be obtained.

In the above, specific preferred embodiment of this invention was shown and described. However, the present invention is not limited to the specific embodiments shown in the above-described embodiments and drawings, and those skilled in the art without departing from the gist of the present invention as defined in the following claims. It should be understood that any person can carry out various modifications and modifications.

As described above, according to the present invention, unlike the prior art, since the impurity removal operation, that is, baking operation is performed on the external electrode fluorescent lamp using the plasma principle without using a heater box, various shapes and In the manufacture of an external electrode fluorescent lamp having a size, there is no need to separately provide a heater box, and the existing system can be used to produce the external electrode fluorescent lamp, which not only facilitates the manufacture of the fluorescent lamp. Significant reductions in manufacturing costs can be achieved.

In addition, the glass tube including the inner electrode and the exhaust pipe for generating plasma is provided in a separate unit unit, bonded to the glass tube, the baking operation or the like, and then removed only, so as a whole, the manufacture of the external electrode fluorescent lamp It's easier to do.

Claims (42)

In the method of manufacturing an external electrode fluorescent lamp, (a) providing a glass tube body in which both ends are open, molded in a shape and size corresponding to the end use of the external electrode fluorescent lamp, and an inner wall portion of which is formed with a fluorescent material except for a portion where the external electrode is formed; Steps, (b) bonding a second glass tube including an internal electrode for plasma generation to both ends of the glass tube body; (c) performing shaft forming to narrow the tube diameter of the glass tube body adjacent to the junction of the glass tube body and the second glass tube; (d) connecting an exhaust pipe to a combination of the glass tube body and the second glass tube; (e) evacuating the interior of the assembly through an exhaust device connected to the exhaust pipe; (f) performing a baking operation by generating a plasma in the glass tube through a plasma generator connected to the plasma generating internal electrode; (g) exhausting residual air or foreign matter in the glass tube and injecting an inert gas into the glass tube; (h) removing the internal electrode and the exhaust pipe for plasma generation (i) forming an external electrode on the glass tube External electrode fluorescent lamp manufacturing method comprising a. delete The method according to claim 1, wherein the second glass tube is bonded to one end of the glass tube including the inner electrode for generating plasma, and the air through the other side of the glass tube body to form a hole to connect the exhaust pipe And bonding the glass tube including the remaining inner electrode for plasma generation to the other side of the glass tube main body to both ends of the glass tube main body. The method of claim 3, wherein the exhaust pipe is connected to the second glass tube at a position adjacent to the inner electrode for plasma generation. delete In the method of manufacturing an external electrode fluorescent lamp, (a) providing a glass tube body having both ends open and molded in a shape and size corresponding to the use of the external electrode fluorescent lamp, wherein an inner wall except for a part of the inner wall near the both ends is coated with a fluorescent material; (b) bonding a pair of second glass tubes, one end of which is closed, to both ends of the glass tube body, and then bending molding the second glass tube to be parallel to the glass tube body; (c) a pair of third glass tubes containing an inner electrode for plasma generation, the third glass tubes including connecting portions having a diameter smaller than the diameter of the glass tubes are connected in a vertical relationship to the second glass tubes through the connecting portions, respectively; To communicate with the second glass tube; (d) connecting an exhaust pipe to any one of the pair of third glass tubes to evacuate the inside of the connected glass tube; (e) performing a baking operation by generating a plasma in the glass tube through a plasma generator connected to the plasma generating internal electrode; (f) exhausting residual air or foreign matter in the glass tube, (g) injecting an inert gas into the glass tube through the exhaust pipe; (h) removing the third glass tube and the exhaust pipe including the plasma generating internal electrode; External electrode fluorescent lamp manufacturing method comprising a. delete The method of claim 6, further comprising forming an external electrode on the surface of the second glass tube after the step (h). delete In the method of manufacturing an external electrode fluorescent lamp, (a) providing a glass tube body having both ends open and molded in a shape and size corresponding to the use of the external electrode fluorescent lamp, wherein an inner wall except for a part of the inner wall near the both ends is coated with a fluorescent material; (b) bonding a pair of second glass tubes, one end of which is closed, to both ends of the glass tube body, and then bending molding the second glass tube to be parallel to the glass tube body; (c) third and fourth glass tubes containing internal electrodes for plasma generation, each of the third and fourth glass tubes including a connecting portion having a first diameter smaller than the diameter of the glass tube through the connecting portions, respectively; Connecting in a vertical relationship to communicate with the second glass tube; (d) connecting an exhaust pipe to the third glass tube to vacuum the interior of the bonded glass tube body and the second glass tube; (e) performing a baking operation by generating a plasma in the glass tube through a plasma generator connected to the plasma generating internal electrode; (f) exhausting residual air or foreign matter in the glass tube, (g) injecting primary inert gas into the glass tube through the exhaust pipe; (h) removing the fourth glass tube to which the exhaust pipe is not connected from the second glass tube, and reducing the connecting portion of the third glass tube to a second diameter smaller than the first diameter; (i) evacuating the inert gas leaving only the amount for the discharge of the lamp; (j) removing the third glass tube from the second glass tube External electrode fluorescent lamp manufacturing method comprising a. delete delete The method for manufacturing an external electrode fluorescent lamp according to claim 6 or 10, wherein the second glass tube includes an external electrode on a surface thereof. The method of claim 10, wherein in step (g), an inert gas is introduced such that the pressure inside the glass tube is less than atmospheric pressure. 11. The method of claim 10, wherein the step (i) further comprises the step of completely exhausting the inert gas, and the step of introducing an inert gas secondary for the discharge of the lamp. delete In the external electrode fluorescent lamp manufacturing method, (a) providing a glass tube body having both ends open and molded in a shape and size corresponding to the use of the external electrode fluorescent lamp, wherein an inner wall except for a part of the inner wall near the both ends is coated with a fluorescent material; (b) a second glass tube containing an internal electrode for plasma generation, the second glass tube including a connecting portion having a first diameter smaller than the diameter of the glass tube and a third glass tube whose one end is closed through the connecting portion; Bonding the glass tubes of the first and second unit structures which are vertically connected to communicate with each other at both ends of the glass tube body, and then bending molding the glass tubes to be parallel to the glass tube body; (c) connecting an exhaust pipe to one of the second glass tubes, and evacuating the interior of the laminated glass tube; (d) generating a plasma inside the laminated glass tube through a plasma generator connected to the internal electrode for plasma generation to perform a baking operation; (e) evacuating the remaining air or foreign matter in the glass tube, (f) injecting an inert gas into the glass tube primarily through the exhaust pipe; (g) removing the second glass tube to which the exhaust pipe is not connected from the third glass tube, and reducing the connecting portion of the second glass tube to which the exhaust pipe is connected to a second diameter smaller than the first diameter; (h) evacuating the inert gas leaving only the amount for the discharge of the lamp; (i) removing the second glass tube to which the exhaust pipe is connected from the third glass tube; External electrode fluorescent lamp manufacturing method comprising a. delete The method of claim 17, further comprising forming an external electrode on the surface of the third glass tube after the step (i). The method of claim 17, wherein the third glass tube comprises an external electrode on a surface thereof. delete 21. The method of any one of claims 17, 19 and 20, wherein step (h) further comprises the step of further completely evacuating the inert gas and introducing the second inert gas for discharge of the lamp. An external electrode fluorescent lamp manufacturing method. delete In the external electrode fluorescent lamp manufacturing method, (a) providing a glass tube body having both ends open and molded in a shape and size corresponding to the use of the external electrode fluorescent lamp, wherein an inner wall except for a part of the inner wall near the both ends is coated with a fluorescent material; (b) bonding a glass tube of a unit structure comprising a first glass tube section including an internal electrode for plasma generation and a second glass tube section bonded to the glass tube body at both ends of the glass tube body, (c) connecting an exhaust pipe to one of the glass tubes including the inner electrode, and evacuating the inside of the laminated glass tube; (d) generating a plasma inside the laminated glass tube through a plasma generator connected to the internal electrode for plasma generation to perform a baking operation; (e) exhausting residual air or foreign matter in the glass tube and injecting an inert gas into the glass tube; (f) removing the first glass tube section and exhaust pipe comprising the internal electrode External electrode fluorescent lamp manufacturing method comprising a. delete delete delete 25. The method of manufacturing an external electrode fluorescent lamp according to claim 24, wherein between the first glass tube section and the second glass tube section, the tube is formed to have a narrow tube diameter. delete 25. The method of claim 24, wherein said exhaust pipe is connected to said first glass tube section. In the external electrode fluorescent lamp manufacturing method, (a) providing a glass tube body molded into a shape and size corresponding to the use of the external electrode fluorescent lamp, the inner wall of which is coated with a fluorescent material; (b) a glass tube having a unit structure comprising a first glass tube section including an internal electrode for plasma generation, a second glass tube section bonded to the glass tube body, and a third glass tube section serving as an exhaust pipe, arranged side by side with the glass tube body Then joining the second glass tube sections near both ends of the glass tube body, respectively; (c) evacuating the interior of the glass tube and the coated glass tube body of the bonded unit structure through an exhaust device connected to the third glass tube section; (d) generating a plasma in the glass tube through a plasma generator connected to the internal electrode for plasma generation to perform a baking operation; (e) removing the first glass tube section; (f) exhausting residual air or foreign matter in the glass tube and injecting an inert gas into the glass tube; (g) removing the third glass tube section External electrode fluorescent lamp manufacturing method comprising a. delete delete delete 32. The method of manufacturing an external electrode fluorescent lamp according to claim 31, wherein between the first glass tube section and the second glass tube section, and between the second glass tube section and the third glass tube section, the tube is formed to have a narrow tube diameter. 36. The manufacture of an external electrode fluorescent lamp according to claim 35, wherein a diameter of the shaft tube forming portion between the first glass tube section and the second glass tube section is larger than a diameter of the shaft tube forming portion between the second glass tube section and the third glass tube section. Way. A glass tube having a unit structure connected to a fluorescent substance coated glass tube for an external electrode fluorescent lamp, wherein the inner electrode for plasma generation and the inside of the fluorescent substance coated glass tube are connected to the fluorescent substance coated glass tube to generate a plasma inside the glass tube. And a second glass tube section interconnected to communicate with the fluorescent substance coated glass tube, the first glass tube section including an exhaust pipe for removing impurities, foreign matters, etc. in the fluorescent material and injecting an inert gas. A glass tube of a unit structure, wherein a shaft tube is formed between the first glass tube section and the second glass tube section to have a narrower diameter. A glass tube having a unit structure connected to a fluorescent substance coated glass tube for an external electrode fluorescent lamp, comprising: a first glass tube section including an inner electrode for plasma generation after being connected to the fluorescent substance coated glass tube and generating a plasma inside the glass tube; A second glass tube section interconnected to communicate with the fluorescent substance coated glass tube and a third glass tube section for evacuating the inside of the fluorescent substance coated glass tube, removing impurities or foreign substances in the fluorescent substance, and serving as an exhaust pipe for injecting inert gas Wherein the first and second glass tube sections and between the second glass tube section and the third glass tube section are axially shaped to narrow the tube diameter. delete delete delete The glass tube of a unit structure according to claim 38, wherein the tube diameter of the shaft tube forming portion between the first glass tube section and the second glass tube section is larger than the diameter of the shaft tube forming portion between the second glass tube section and the third glass tube section.

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