JP2000208097A - Double wall tube discharge tube and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a double wall tube discharge tube that can enhance heat insulation and can provide a practically sufficient luminance characteristic under a low-voltage drive condition or under a low-temperature environment. SOLUTION: For this double wall tube discharge tube 1, space adjusting projections 7A-7D for uniformly adjusting the dimension of an airtight space 6 between a first sealed tube (inner tube) 2 and a second sealed tube (outer tube) 3 are provided. In this case, the space adjusting projections 7A-7D are formed by partially heating and melting the second sealed tube 3, and the tip parts of the space adjusting projections 7A-7D are formed into such a shape as to come into point contact when abutting on the first sealed tube 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double tube type discharge tube and a method for manufacturing the same, and more particularly to a double tube type cold cathode fluorescent tube capable of obtaining sufficient luminance under a low temperature environment or a low voltage driving state. And its manufacturing method.

[0002]

2. Description of the Related Art In a backlight type liquid crystal display device used in a personal computer, a word processor, a small portable television, an in-vehicle television, and the like, a liquid crystal display substrate is illuminated by a fluorescent discharge tube (fluorescent lamp). The fluorescent discharge tube is required to be small and to have sufficiently low power consumption.

However, when used in a low temperature environment,
Because the temperature of this kind of fluorescent discharge tube does not rise enough,
The mercury vapor pressure in the tube was lowered to lower the luminous efficiency, and the fluorescent discharge tube could not obtain sufficient luminance.

In order to solve such technical problems, a double-tube cold-cathode fluorescent discharge tube (double-tube CFL) tends to be generally used. FIG. 10 is a sectional structural view of a double-tube cold-cathode fluorescent discharge tube according to the prior art. As shown in FIG. 10, a double-tube cold-cathode fluorescent discharge tube 11 includes an inner tube 12 and an outer tube 1 that covers the inner tube 12 with an airtight space 16 interposed therebetween.
3, a pair of discharge electrodes 14A disposed in the inner tube 12,
14B, a terminal 15A connected to the discharge electrode 14A and a terminal 15B connected to the discharge electrode 14B. Each of the terminals 15A and 15B extends from the inside of the inner tube 12 to the outside of the outer tube 13.

[0005] Both ends of the inner tube 12 and the outer tube 13 are integrally formed by fusion bonding. Although not shown, the inner tube 1
A fluorescent film for emitting visible light in response to the irradiation of ultraviolet rays generated by the discharge is formed on the inner wall of 2.
Further, a discharge gas composed of a mixed gas of neon gas and argon gas is sealed in the inner tube 12 at a predetermined pressure. The hermetic space 16 between the inner tube 12 and the outer tube 13 is kept in a high vacuum state, and the heat insulating effect of the inner tube 12 is enhanced.

The double-tube cold-cathode fluorescent discharge tube 11 having the above-described configuration is used to provide an airtight space 1 between the inner tube 12 and the outer tube 13.
6 is held in a high vacuum state having a low heat transfer property, the heat of the inner tube 12 hardly escapes to the outside, and sufficient luminance can be obtained under a low temperature environment or a low voltage driving state. It was expected to be.

FIGS. 11 to 15 are process sectional views of a double-tube cold-cathode fluorescent discharge tube shown for each manufacturing process for explaining the manufacturing method.

(1) First, an inner tube 12 in which both ends of a tubular elongated glass tube are hermetically sealed as shown in FIG. 11 is prepared.
Further, a cylindrical and elongated glass tube 13A having an inner diameter larger than the outer diameter of the inner tube 12 as shown in FIG. 12 is prepared. A discharge electrode 14A and a terminal 15A are provided at one end on the left side of FIG. 11 of the inner tube 12, and a discharge electrode 14B and a terminal 15B are provided at the other end on the right side in FIG. Both ends of the glass tube 13A are open and unsealed.

(2) Next, as shown in FIG. 13, a spacer 18 is attached to the inner tube 12. The inner diameter of the spacer 18 is set to be substantially the same as the outer diameter of the inner tube 12, and mounting is performed in a state where the outer peripheral surface of the inner tube 12 is in contact with the inner peripheral surface of the spacer 18. One end of the spacer 18 is located at the discharge electrode 14A, and the other end thereof is
Is drawn out of the inner tube 12 in order to extract and discharge.

(3) Further, as shown in FIG. 13, a glass tube 13A is mounted on the inner tube 12 with a spacer 18 interposed therebetween. The outer diameter of the spacer 18 is set to be substantially the same as the inner diameter of the glass tube 13A, and mounting is performed in a state where the inner peripheral surface of the glass tube 13A and the outer peripheral surface of the spacer 18 are in contact with each other. One end of the glass tube 13A on the left side in FIG.
2 is disposed at a position surrounding one end.

(4) As shown in FIG.
One end of A is melted, and one end of the glass tube 13A and one end of the inner tube 12 are hermetically sealed by fusion bonding. In this step, the distance between the outer peripheral surface of the inner tube 12 and the inner peripheral surface of the glass tube 13A is kept uniform by the spacer 18.

(5) Thereafter, the inner tube 12 and the glass tube 13A
Is removed from the other end of the glass tube 13A and discharged. By discharging the spacer 18, a space is formed between the inner tube 12 and the glass tube 13A.

(6) Subsequently, the inside of the glass tube 13A is evacuated from the other end in the open state of the glass tube 13A, and after reaching a predetermined high vacuum state, the other end of the glass tube 13A is melted. As shown in FIG. 15, the other end of the glass tube 13A is hermetically sealed, and an airtight space 16 is created inside the glass tube 13A.

(7) Finally, the other end of the glass tube 13A is melted, and the other end of the glass tube 13A and the other end of the inner tube 12 are fused and joined. An extra portion on the side is cut out, and as shown in FIG. 10, the terminal 15B is led out from the other end on the right side. That is, by removing an extra portion on the right side of the glass tube 13A, the glass tube 13A is removed.
An outer tube 13 is formed from A. As a result, the double-tube cold-cathode fluorescent discharge tube 11 is completed.

[0015]

However, in the above-described double-tube cold-cathode fluorescent discharge tube 11, no consideration was given to the following points.

(1) After the one end of the inner tube 12 and the one end of the glass tube 13A shown in FIG. 14 are fused and connected, the spacer 18 is extracted and discharged. 13A, it became cantilevered, and the other end of the inner tube 12 was drooped by its own weight or by bending, and it was easy to come into contact with the inner wall of the outer tube 13.
Such contact of the inner tube 12 with the inner wall of the outer tube 13 causes loss of uniformity of the hermetic space between the inner tube 12 and the outer tube 13 (uniformity of the thickness of the hermetic space), and causes the inner tube 12 and the outer tube 13 to contact each other. Since heat is intensively discharged from the inner tube 12 to the outside of the outer tube 13 at the contact portion with the tube 13, the heat insulation property is deteriorated, and the expected luminance under a low temperature environment or a low voltage driving state is obtained. No properties could be obtained.

(2) A step of mounting the spacer 18 on the inner tube 12 because the spacer 18 is required, FIG.
The glass tube 1 is formed by interposing a spacer 18 in the inner tube 12 shown in
The step of mounting the 3A, the step of melting and joining one end of the inner tube 12 and one end of the glass tube 13A shown in FIG. 13 and then extracting and discharging the spacer 18 are incorporated in the manufacturing process, thereby increasing the number of manufacturing steps. This complicates the manufacturing process.

(3) The productivity is reduced due to the increase in the number of manufacturing steps, and the manufacturing cost and the product cost are increased.

(4) At the time of mounting, the spacer 18 is attached to the inner tube 1
2. In order to discharge the spacer 18 in a state in which the spacer 18 is brought into contact with each of the glass tubes 13A and is brought into contact with each of the inner tube 12 and the glass tube 13A at the time of discharge,
Each of the glass tubes 13A may be damaged or broken. If damage or breakage occurs, the double-tube cold-cathode fluorescent discharge tube 11 becomes a defective product, which lowers the production yield.

(5) A series of operations from the mounting of the spacer 18 to the discharge thereof is complicated, and the operation of the spacer 18 is controlled with high precision so as not to damage or damage the inner tube 12 or the outer tube 13. Has been practically difficult to build automation of the manufacturing process.

The present invention has been made to solve the above problems. Accordingly, an object of the present invention is to improve the heat insulating effect and to obtain a double tube discharge tube capable of obtaining excellent luminance characteristics under a low temperature environment or a low voltage driving state (low power driving state). It is to provide.

A further object of the present invention is to provide a double-tube discharge tube capable of maintaining the dimensions of the hermetically sealed space even under the influence of a drop or vibration and stably maintaining the heat insulating effect. is there.

An object of the present invention is to provide a low-voltage driving state (low-power driving state) and a severe operating environment.
An object of the present invention is to provide a double-tube discharge tube having stable luminance characteristics.

Still another object of the present invention is to provide a method of manufacturing a double tube type discharge tube capable of simplifying the manufacturing process and reducing the manufacturing cost and having a high manufacturing yield.

[0025]

Means for Solving the Problems In order to solve the above-mentioned problems, a first feature of the present invention is that a first sealing tube in which a pair of discharge electrodes is disposed and a discharge gas is sealed. (Inner tube)
And a second envelope tube (outer tube) covering the periphery of the first envelope tube with an airtight space interposed therebetween, and in the vicinity of the discharge electrode,
It is a double tube type discharge tube provided with a space adjusting projection for adjusting the size of the airtight space, which is disposed between the first envelope tube and the second envelope tube. Here, the "space adjustment projection" is for maintaining the dimensions of the hermetic space between the first envelope tube and the second envelope tube uniformly near each of the pair of discharge electrodes. For example, when the first envelope tube is formed of an elongated tubular glass tube, and the second envelope tube is formed of an elongated tubular glass tube having a diameter larger than that of the first envelope tube,
The “space adjusting projection” is configured such that the first sealed tube is disposed at the center of the second sealed tube, and the dimension of the airtight space near the discharge electrode between the first sealed tube and the second sealed tube. Can be adjusted uniformly. Further, in the double-tube discharge tube according to the first aspect of the present invention, "in the vicinity of the discharge electrode" means that the tip of the discharge electrode and the first and second sealed tubes are melted. It is between joints. The space adjusting projection may be disposed between the first envelope tube and the second envelope tube in the vicinity of at least one of the pair of discharge electrodes, and in the vicinity of each of the pair of discharge electrodes. It may be arranged.

In the double-tube discharge tube configured as described above, the hermetic space (thickness of the hermetic space) between the first envelope tube and the second envelope tube is made uniform at least near the discharge electrode. By keeping the dimensions to be small, the heat insulating effect of the airtight space can be improved, and in particular, the luminance characteristics in a low voltage driving state (low power driving state) and a low temperature environment can be improved.

In the double-tube discharge tube according to the first aspect of the present invention, the space adjusting projection is made of, for example, the same material as the second envelope tube and is integrally formed with the second envelope tube. It may be configured so as to protrude from the inner wall of the second sealed tube toward the first sealed tube.

Further, in the double tube type discharge tube according to the first aspect of the present invention, the shape of the double tube type discharge tube is such that the protruding tip portion of the space adjusting projection can make point contact with the first or second sealed tube. It is preferable to form it. Here, the “shape such that the protruding tip portion of the space adjustment projection can be in point contact”
Even if the tip portion of the space adjusting projection comes into contact with the first sealing tube or the second sealing tube, the heat of the first sealing tube hardly escapes to the second sealing tube through the space adjusting projection. For example, it is preferable that the tip portion of the space adjusting projection is formed in a shape such as a needle shape or a conical shape. By making the distal end of the space adjusting projection point-contactable, the thermal resistance value of the contact portion can be increased even when it comes into contact with the first envelope tube. As a result, the heat of the first sealed tube can hardly escape to the second sealed tube, so that the heat insulating effect can be improved, and the luminance characteristics can be further improved. Further, this space adjusting projection is provided with the first
Preferably, it is located outside the effective light emitting area of the envelope tube. Here, “outside the effective light emitting area of the first envelope tube” means
This means that the space adjustment projection does not impede light output. By arranging the space adjusting projections outside the effective light emitting area of the first enclosure tube in this manner, the space adjusting projections do not prevent light from being emitted, and the luminance characteristics in a low temperature environment are further improved. Can be improved.

A second feature of the present invention is that a step of preparing a first sealed tube in which a pair of discharge electrodes is disposed and in which a discharge gas is sealed is provided. Second to coat
A step of preparing a sealed tube and forming a space adjusting projection projecting from an inner wall of the second sealed tube toward a central axis of the second sealed tube at a predetermined position of the second sealed tube; Inside the second envelope tube, such that the space adjustment protrusion faces the vicinity of the electrode for
A step of inserting the first envelope tube and adjusting a dimension between the first envelope tube and the second envelope tube by the space adjusting projection, and evacuating the inside of the second envelope tube to a predetermined ultimate pressure. A double step including a step of evacuating and a step of melt-bonding the end of the first envelope tube and the second envelope tube to form an airtight space between the first and second envelope tubes. This is a method of manufacturing a tube-type discharge tube.

In such a method of manufacturing a double-tube discharge tube, when the first envelope tube is disposed inside the second envelope tube, the first envelope tube or the second envelope tube is previously placed on the first envelope tube or the second envelope tube. The arrangement position of the first envelope tube can be adjusted by the formed space adjustment projection. Therefore, the use of the conventional spacer can be eliminated, the step of attaching the spacer to the first envelope tube, the step of attaching the second envelope tube with the spacer interposed in the first envelope tube, and the discharging of the spacer. Process can be eliminated,
The manufacturing process of the double tube type discharge tube can be simplified, and the number of manufacturing processes can be reduced. Further, since complicated operations of the spacer such as the mounting operation and the discharging operation of the spacer can be eliminated, the automation of production of the double tube discharge tube can be realized. Further, damage or breakage of the sealing tube or entry of foreign matter due to a spacer mounting operation, a discharging operation, and the like can be prevented, so that the production yield can be improved. Furthermore, by simplifying the manufacturing process, the manufacturing cost can be reduced.

Further, in such a method for manufacturing a double tube discharge tube, the space adjusting projection of the second tube is disposed near the discharge electrode at the end of the first tube and the second tube. It may be provided at a fusion joint for melting the body tube. As a result, after the manufacture, the space adjusting projections do not remain, but the arrangement positions of the first sealing tube and the second sealing tube can be adjusted.

It is to be noted that the provision of the space adjusting projection near the discharge electrode and outside of the fusion joint rather than at the fusion joint results in a better arrangement of the first and second sealing tubes. It can be regulated more precisely. This is because the end shapes of the first envelope tube vary in the manufacturing process, and the arrangement positions of the first envelope tube and the second envelope tube vary due to this shape variation.

[0033]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional structural view of a double tube discharge tube (double tube cold cathode fluorescent discharge tube) according to the first embodiment of the present invention. As shown in FIG. 1, a double-tube discharge tube 1 according to a first embodiment of the present invention has a pair of discharge electrodes 4A and 4B disposed inside, and a discharge gas is sealed therein. 1 sealed tube (inner tube) 2
A second sealing tube (outer tube) 3 that covers the periphery of the first sealing tube 2 with an airtight space 6 interposed therebetween, and a first sealing tube near each of the pair of discharge electrodes 4A and 4B. There are provided space adjustment projections 7A, 7B, 7C and 7D arranged between the second sealing tube 3 and the second sealing tube 3 for adjusting the size of the airtight space 6.

The first sealing tube 2 is a sealing tube formed of an elongated cylindrical glass material having an outer diameter of, for example, 1.4 mm to 1.8 mm. The second sealed tube 3 is a sealed tube formed of an elongated cylindrical glass material having an outer diameter of, for example, 2.4 mm to 2.6 mm larger than the outer diameter of the first sealed tube 2. is there. In this way, by selecting the external dimensions of both, the second sealing tube 3
The first sealing tube 2 can be disposed inside the inside of the container. Both ends of the first envelope tube 2 and the second envelope tube 3 are integrally formed by fusion bonding. As a result (from the relationship of the external dimensions described above), the size of the hermetic space 6 between the first sealing tube 2 and the second sealing tube 3 is about 0.45 mm or more in consideration of the wall thickness.
It becomes about 0.6mm.

Although not shown, the inner wall of the first sealing tube 2
A fluorescent film is applied to emit visible light in response to irradiation of ultraviolet rays generated by electric discharge. Furthermore, the first
The inside of the envelope tube 2 is filled with a required fixed amount of mercury (mercury particles) for generating mercury discharge and a discharge gas for assisting lighting. Argon (Ar) as the discharge gas
A rare gas such as gas or xenon (Xe) gas is used, and the pressure inside the first sealing tube 2 is set to about 5.3 kPa to 13 kPa. A space adjusting projection 7A is provided on the inner wall of the second
Basically, the fluorescent film is not applied including the respective surfaces of 7D to 7D. Note that a fluorescent film can be applied to the inner wall of the second sealed tube 3 for the purpose of increasing the emission rate of visible light.

Each of the pair of discharge electrodes 4A and 4B is formed in a cylindrical shape in the first embodiment, and is formed of an electrode material such as nickel (Ni). The respective electrode shapes of the pair of discharge electrodes 4A and 4B are not particularly limited,
Various shapes such as a dish shape, a bar shape, and a wire shape can be adopted. One end of the terminal 5A is electrically connected to the discharge electrode 4A, and the other end is led out of the second envelope tube 3. Similarly, one end of the terminal 5B is connected to the discharge electrode 4B.
And the other end is led out of the second envelope tube 3. Each of the terminals 5A and 5B is formed of a metal material having good electric conductivity such as nickel, for example.
The terminal 5A and the discharge electrode 4A and the terminal 5B and the discharge electrode 4B are joined by, for example, fusion bonding, brazing, soldering, or the like.

The interior of the hermetic space 6 between the first envelope tube 2 and the second envelope tube 3 is maintained in a high vacuum state in which the heat insulating effect can be most expected in the first embodiment. For example,
It is preferable that the inside of the airtight space 6 is maintained in a high vacuum state of about 133 mPa to 1.3 mPa. Further, the inside of the hermetic space 6 is a heat-insulating gas having poor thermal conductivity (high thermal resistance value), for example, one of argon gas, ethylene gas, ethane gas, nitric oxide gas, krypton gas, and freon gas.
It can be filled with a kind of gas or a mixed gas obtained by mixing a plurality of kinds of gases.

In the first embodiment, the space adjusting projections 7A to 7D are formed integrally with the second sealing tube 3 using the same material as the second sealing tube 3. 3 is configured to protrude from the inner wall toward the first sealing tube 2. By these space adjusting projections 7A to 7D,
The dimensions of the hermetic space 6 (thickness of the hermetic space 6) between the first envelope tube 2 and the second envelope tube 3 are at least the discharge electrodes 4A and 4
B is provided to maintain uniformity in the discharge region between the two.

The space adjusting projections 7A and 7B are disposed in the vicinity of the discharge electrode 4A on the left side in FIG. 1, specifically, in a region outside the effective light emitting area of the first envelope tube 2. This area is
In the dark part of the double tube discharge tube 1 (discharge electrode 4A in FIG. 1)
And the area on the left side from the discharge electrode 4B). FIG. 2 is an enlarged sectional structural view of the double-tube discharge tube 1 taken along the line F2-F2 in FIG. The dimensions of the hermetic space 6 are kept uniform (in FIG. 1, the dimensions of the hermetic space 6 between the upper outer peripheral surface of the first envelope tube 2 and the upper inner peripheral surface of the second envelope tube 3, In order to keep the size of the airtight space 6 between the lower outer peripheral surface of the body tube 2 and the lower inner peripheral surface of the second sealed tube 3 uniform), a space is provided on the upper inner peripheral surface of the second sealed tube 3. An adjustment projection 7A is provided, and a lower portion of the second envelope tube 3 at a position facing the space adjustment projection 7A, that is, a position rotated by about 180 degrees with respect to the central axis of the first envelope tube 2. A space adjusting projection 7B is provided on the peripheral surface. The distal end portions of the space adjusting projections 7A and 7B are formed so as to be in contact with the outer peripheral surface of the first envelope tube 2 or to be close to each other with a slight gap therebetween. That is, the dimension between the leading end of the space adjusting projection 7A and the leading end of the space adjusting projection 7B is
Is set to be substantially the same as the outer diameter of the first sealing tube or slightly larger than the outer diameter of the first sealing tube 2.

Similarly, the space adjusting projections 7C and 7D are
It is arranged near the discharge electrode 4B on the right side in FIG. In order to keep the dimensions of the airtight space 6 uniform, a space adjusting projection 7C is arranged on the inner peripheral surface of the upper part of the second sealing tube 3, and the first sealing tube 2 is provided.
At the opposite position rotated about 180 degrees around
A space adjusting projection 7D is provided on the lower inner peripheral surface of the envelope tube 3. Each of the distal end portions of the space adjusting projections 7C and 7D is in contact with the outer peripheral surface of the first envelope tube 2 or holds a slight gap similarly to the respective distal end portions of the space adjusting projections 7A and 7B. Are formed so as to be close to each other. That is, the leading edge of the space adjustment projection 7C and the space adjustment projection 7C
The dimension between D and the front end is set to be substantially the same as the outer diameter of the first envelope tube 2 or slightly larger than the outer diameter of the first envelope tube 2. .

Each of the distal ends of the space adjusting projections 7A, 7B, 7C, 7D is formed to have a point contact with the outer peripheral surface of the first envelope tube 2.
1 and 2, the space adjusting projections 7A, 7B,
Although the shape of the tip of 7C, 7D is formed in a conical shape, in the first embodiment of the present invention, the shape of the tip of these space adjusting projections 7A, 7B, 7C, 7D is a needle. Other shapes, such as a shape, may be sufficient.

In the double tube discharge tube 1 according to the first embodiment of the present invention as described above, the first sealed tube 2
The heat insulating effect of the airtight space 6 is desired by keeping the airtight space 6 (thickness of the airtight space 6) between the airtight space 6 and the second sealing tube 3 at least uniform between the discharge electrodes 4A and 4B. , And the luminance characteristics particularly under a low temperature environment can be stably maintained. At the same time, the space adjusting projections 7A and 7B are arranged near the discharge electrode 4A, and the space adjusting projections 7C and 7D are arranged near the discharge electrode 4B. Derivation is not hindered, and luminance characteristics in a low temperature environment can be improved.

Further, in the double-tube discharge tube 1 according to the first embodiment of the present invention, the space adjusting projections 7A to 7D come into contact with the first envelope tube 2. Since the thermal resistance of the contact portion can be increased by the point contact, and the heat of the first sealing tube 2 can be hardly released to the second sealing tube 3, the heat insulating effect can be improved. The luminance characteristics can be further improved.

Further, the double-tube discharge tube 1 according to the first embodiment of the present invention has a space adjusting projection even when the double-tube discharge tube 1 is dropped or vibrated. 7A to 7D, the first sealing tube 2 can be maintained at the central portion of the second sealing tube 3, so that the heat insulating effect of the airtight space 6 can be improved, and stable luminance characteristics can always be obtained. it can.

Next, a method for manufacturing the double tube type discharge tube according to the first embodiment of the present invention will be briefly described with reference to sectional views shown in FIGS.

(1) First, as shown in FIG. 3, a first sealing tube 2 is formed by using a known glass cutting technique, a glass shielding technique, or the like. The first envelope tube 2 has a fluorescent film applied to the inner wall, a discharge gas filled therein, discharge electrodes 4A and 4B formed inside, and terminals 5A and 5B drawn out from inside to outside. It is formed in a state where it is set.

(2) In order to form the second sealed tube 3, a glass tube 3A shown in FIG. 4 is prepared. The glass tube 3A is formed in an elongated cylindrical shape, and both ends of the right and left glass tubes 3A in FIG. 4 are open.

(3) Next, as shown in FIG. 5, a predetermined position of the glass tube 3A serving as the second sealing tube is moved from the inner wall of the second sealing tube (glass tube) 3A to the second sealing tube. (Glass tube) 3
A plurality of space adjusting projections 7 protruding toward the central axis of A
A, 7B, 7C and 7D are formed. The “predetermined position” means a position near the discharge electrodes 4A and 4B of the first sealed tube 2 after the completion of the double tube discharge tube. This predetermined position can be determined by measuring the distance between the discharge electrodes 4A and 4B of the first envelope 2 in advance, or from the design data.
It can be easily estimated (designed). That is, each of the space adjusting projections 7A and 7B is formed on the inner peripheral surface of the glass tube 3A at a position estimated to be near the discharge electrode 4A. In addition, each of the space adjusting projections 7C and 7D is formed at a position estimated to be near the discharge electrode 4B of the first envelope tube 2. These space adjusting projections 7A to 7D are
A predetermined portion of the glass tube 3A is heated and melted by a gas burner, and the heated and melted portion is formed by protruding with a pin having a predetermined stroke. Due to the stroke of the pin, the height of the space adjusting projections 7A to 7D from the inner peripheral surface of the glass tube 3A is set to the dimension of the hermetic space 6 shown in FIGS.
Is substantially equal to or slightly lower than
The leading edge height of the space adjusting projections 7A, 7B, 7C, and 7D protruding inward is adjusted. Thus, the dimension between the tip of the space adjusting projection 7A and the tip of the space adjusting projection 7B, and the dimension between the tip of the space adjusting projection 7C and the tip of the space adjusting projection 7D are all smaller. The outer diameter of the first sealing tube 2 can be set substantially equal to or slightly larger than the outer diameter. Although the number of steps is slightly increased, the inside of the glass tube 3A is depressurized by a predetermined evacuation device, and in this depressurized state, a predetermined position of the glass tube 3A is selectively heated and melted by a gas burner. The glass melted at the position (1) may be drawn into the interior to form the space adjusting projections 7A, 7B, 7C and 7D.

(4) As shown in FIG. 6, a pair of discharge electrodes are provided at respective positions of the plurality of space adjusting projections 7A to 7D while utilizing the plurality of space adjusting projections 7A to 7D thus formed. The first sealing tube 2 is inserted and disposed inside the glass tube 3A so that 4A and 4B face each other. Here, the first sealing tube 2 is provided with space adjusting projections 7A to 7D.
The glass tube 3A is inserted into the glass tube 3A while being in contact with the tip of the glass tube 3A, so that the arrangement position of the first sealing tube 2 is adjusted substantially at the center of the glass tube 3A. That is, the size of the hermetic space 6 between the first sealing tube 2 and the second sealing tube 3 shown in FIGS. 1 and 2 is uniformly adjusted.

(5) As shown in FIG. 7, one end (left side in FIG. 7) of the first sealing tube 2 and one end of the glass tube 3A are joined by melting, and this one end is hermetically sealed. . The other end of the glass tube 3A remains open.

(6) Then, the inside of the glass tube 3A is evacuated from the other open end of the glass tube 3A by a vacuum exhaust device such as a turbo molecular pump, a cryopump, an oil diffusion pump, etc. 133mPa ~ 1.3m
Set the background pressure (ultimate pressure) to about Pa.

(7) The internal pressure of the glass tube 3A is 133 mPa-
When the pressure in the range of 1.3 mPa is reached, the exhaust is stopped,
While maintaining this internal pressure, the other end of the glass tube 3A is hermetically sealed by fusion bonding, as shown in FIG. 8, to form an airtight space 6 between the first sealed tube 2 and the glass tube 3A.

(8) Then, as shown in FIG.
One end side (left side in FIG. 1) of the first sealing tube 2 and the glass tube 3A
The second sealing tube 3 is formed from the glass tube 3A by melting (sealing off) one end side of the glass tube 3A, and the excess glass tube 3A is cut off and removed. The double-tube discharge tube 1 according to the first embodiment is completed through a series of these manufacturing steps.

In the above-described method for manufacturing a double-tube discharge tube according to the first embodiment of the present invention, when the first sealed tube 2 is disposed inside the second sealed tube 3, The arrangement position of the first envelope tube 2 can be adjusted by the space adjusting projections 7A to 7D formed in advance on the glass tube 3A (second envelope tube 3). Therefore, the use of the spacer 18 shown in FIGS. 13 and 14 can be eliminated, and the step of attaching the spacer 18 to the first envelope tube 2 and the step of attaching the spacer 1 to the first envelope tube 2 are performed.
Since the step of mounting the glass tube 3A (the second sealing tube 3) and the step of discharging the spacer 18 can be eliminated with the interposition of the glass tube 8, the manufacturing process of the double tube discharge tube 1 is simplified ( The number of manufacturing steps can be reduced). further,
Since the complicated operation of the spacer such as the mounting operation and the discharging operation of the spacer 18 can be eliminated, the automation of the production of the double tube discharge tube 1 can be easily realized. further,
Since the damage and destruction of the first sealing tube 2 and the second sealing tube 3 (glass tube 3A) due to the mounting operation and the discharging operation of the spacer 18 can be eliminated, the production yield can be improved. it can. Furthermore, by simplifying the manufacturing process, the manufacturing cost can be reduced.

Further, in the method for manufacturing a double tube discharge tube according to the first embodiment of the present invention, the glass tube 3A
Since the space adjusting projections 7A to 7D of the (second sealing tube 3) can be formed by partial heating and melting using a burner, the space adjusting projections 7A to 7D can be easily formed, and productivity can be improved. Can be improved.

(Second Embodiment) In a second embodiment of the present invention, an example in which a space adjusting projection is provided on a first envelope tube (inner tube) of a double tube discharge tube will be described. Is what you do. FIG. 9 is a sectional structural view of a double tube discharge tube (double tube cold cathode fluorescent discharge tube) according to the second embodiment of the present invention.

The double tube type discharge tube 1 shown in FIG. 9 protrudes into the hermetic space 6 near the discharge electrode 4A of the first envelope tube 2 and has a first
Space adjustment projections 8A and 8B for adjusting the size of the airtight space 6 between the envelope tube 2 and the second envelope tube 3, and a space adjustment projection near the discharge electrode 4B of the first envelope tube 2. 8C and 8D. The space adjusting projections 8A to 8D are all disposed on the outer peripheral surface of the first sealing tube 2. In the second embodiment of the present invention, each of the space adjusting projections 8A to 8D is formed of the same glass material as the first sealing tube 2.
Then, glass materials for space adjustment projections 8A to 8D made of a member separately prepared from the first envelope tube 2 are attached to the outer peripheral surface of the first envelope tube 2 by fusion bonding.

In the double-tube discharge tube 1 configured as described above, the same effect as the double-tube discharge tube 1 according to the first embodiment of the present invention can be obtained. Furthermore, by previously unifying the dimensions of the separately prepared glass materials for the space adjustment projections 8A to 8D, the space adjustment projections 8A to 8D having a uniform height are formed on the outer peripheral surface of the first envelope tube 2. Can be easily attached, and the accuracy of position adjustment is improved.

As a modification of the second embodiment,
In the vicinity of the discharge electrodes 4A and 4B, the first sealing tube 2 may be configured using a glass tube having a space adjusting protrusion protruding toward the airtight space 6 on the outer peripheral surface. In this case, there is no need to perform a step of melting and bonding the glass material for the space adjusting projection to the first sealing tube 2.

(Other Embodiments) Although the present invention has been described with reference to the above-described first and second embodiments, it should be understood that the description and drawings constituting a part of this disclosure limit the present invention. should not do. From this disclosure, various alternative embodiments, examples, and operation techniques will be apparent to those skilled in the art.

For example, in the above-described first and second embodiments, both ends of the first sealing tube 2 and both ends of the second sealing tube 3 are respectively connected by melting. The first envelope tube 2 and the second envelope tube 3 can be connected to each other via a holding member formed of a separate member.

In the first embodiment (or the second embodiment), two space adjusting members are provided, one each for the inner peripheral surface of the second sealing tube 3 at opposing positions. A total of two space adjusting projections 7C and 7D (or 8A) are respectively provided at positions facing the projections 7A and 7B (or 8A and 8B) and the inner peripheral surface of the second sealing tube 3 respectively.
C and 8D) are provided, but a plurality of them may be opposed to each other. For example, a plurality of space adjusting projections are arranged on the inner peripheral surface of the second envelope tube 3 above the discharge electrode 4A on the left side in FIG. A plurality of space adjusting projections are provided on the lower inner peripheral surface of the second envelope tube 3 at a position facing the space adjusting projections, that is, a position rotated by about 180 degrees with respect to the central axis of the first envelope tube 2. It may be arranged. In this case, it goes without saying that a plurality of space adjustment projections also face the discharge electrode 4B on the right side in FIG. In addition, a plurality of space adjusting projections are axially arranged at equal positions on the discharge electrode 4A side and the discharge electrode 4B side, that is, symmetrical positions with respect to a plane bisecting the axis of the second envelope tube 3. It is good to arrange in. In this manner, by arranging a plurality of space adjusting projections in the axial direction, the first sealing tube 2 and the second
The hermetic space 6 (thickness of the hermetic space 6) between itself and the sealing tube 3 can be maintained at a uniform size, and the heat insulating effect of the hermetic space 6 can be improved. Therefore, it is possible to improve the luminance characteristics particularly in a low temperature environment. Further, since the plurality of space adjusting projections are disposed near the discharge electrodes 4A and 4B, the light emission is not hindered.
The luminance characteristics in a low temperature environment can be further improved.

In the vicinity of each of the discharge electrodes 4A and 4B, three
One or more space adjusting projections may be arranged at equal intervals. Further, the number of space adjustment projections arranged in the circumferential direction increases, and as a limit which is continuous with each other, the space adjustment projections are formed in a closed ring along the entire inner peripheral surface of the second sealing tube 3. May be. In this case, it is slightly difficult to adjust the protrusion height with high accuracy. However, the closed annular space adjusting projection does not hinder the light emission, and the heat insulating effect of the airtight space 6 can be improved. it can. For this reason, even in the case of the closed annular space adjusting projection, the luminance characteristics in a low temperature environment can be improved.

As described above, the present invention naturally includes various embodiments and the like not described herein. Therefore, the technical scope of the present invention is defined only by the matters specifying the invention according to the claims that are appropriate from the above description.

[0065]

According to the present invention, it is possible to provide a double-tube discharge tube capable of easily realizing a desired heat insulating effect and stably maintaining it. As a result, it is possible to provide a double tube discharge tube exhibiting excellent luminance characteristics even in a low temperature environment.

Further, according to the present invention, even when the double-tube discharge tube is dropped or vibrated, the dimensions of the hermetic space can be maintained constant, and the heat insulating effect can be maintained stably. . As a result, it is possible to provide a double-tube discharge tube having stable luminance characteristics even in a low-voltage driving state (low-power driving state) or a severe operating environment.

Further, according to the present invention, the reliability is high,
A double-tube discharge tube with low production cost can be provided.

Further, according to the present invention, it is possible to provide a method of manufacturing a double tube discharge tube in which the manufacturing process can be simplified and the manufacturing cost can be easily reduced. At the same time, it is easy to automate,
In addition, it is possible to prevent a damage or breakage of the sealing tube during the manufacturing process or to prevent foreign matter from being mixed therein, and to provide a method for manufacturing a double tube discharge tube having a high manufacturing yield.

[Brief description of the drawings]

FIG. 1 is a sectional structural view of a double tube discharge tube according to a first embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional structure diagram (a cross-sectional structure diagram cut along a line F2-F2 in FIG. 1) of the double-tube discharge tube according to the first embodiment of the present invention;

FIG. 3 is a process sectional view of the double-tube discharge tube according to the first embodiment of the present invention (part 1).

FIG. 4 is a process sectional view of the double-tube discharge tube according to the first embodiment of the present invention (part 2).

FIG. 5 is a process sectional view of the double-tube discharge tube according to the first embodiment of the present invention (part 3).

FIG. 6 is a process sectional view of the double-tube discharge tube according to the first embodiment of the present invention (part 4).

FIG. 7 is a process sectional view of the double-tube discharge tube according to the first embodiment of the present invention (part 5).

FIG. 8 is a process sectional view of the double-tube discharge tube according to the first embodiment of the present invention (part 6).

FIG. 9 is a sectional structural view of a double-tube discharge tube according to a second embodiment of the present invention.

FIG. 10 is a sectional structural view of a double-tube cold-cathode fluorescent discharge tube according to the related art.

FIG. 11 is a process sectional view of a double-tube cold-cathode fluorescent discharge tube according to the related art (part 1).

FIG. 12 is a process sectional view of a double-tube cold-cathode fluorescent discharge tube according to the related art (part 2).

FIG. 13 is a process sectional view of a double-tube cold-cathode fluorescent lamp according to the related art (part 3).

FIG. 14 is a process sectional view of a double-tube cold-cathode fluorescent lamp according to the related art (part 4).

FIG. 15 is a process sectional view of a double-tube cold-cathode fluorescent lamp according to the related art (part 5).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Double tube type discharge tube 2 1st sealed tube (inner tube) 3 2nd sealed tube (outer tube) 4A, 4B Discharge electrode 5A, 5B terminal 6 Airtight space 7A-7D, 8A-8D For space adjustment Projection 3A glass tube

Claims (5)

[Claims] 1. A first sealing tube in which a pair of discharge electrodes is disposed and in which a discharge gas is sealed, and a second sealing tube surrounding the first sealing tube via an airtight space. A sealing tube, and a space adjusting projection for adjusting the size of the hermetic space, which is arranged between the first sealing tube and the second sealing tube in the vicinity of the discharge electrode. A double-tube discharge tube, comprising: 2. The space adjusting projection is made of the same material as the second sealing tube and is integrally formed with the second sealing tube.
2. The double-tube discharge tube according to claim 1, wherein the double-tube discharge tube protrudes from an inner wall of the second envelope tube toward the first envelope tube. 3. 3. The double tube according to claim 1, wherein the protruding tip portion of the space adjusting projection is formed in a shape capable of making point contact with the first envelope tube. Discharge tube. 4. The double tube discharge according to claim 1, wherein the space adjusting projection is located outside an effective light emitting area of the first envelope tube. tube. 5. A method for producing a double tube discharge tube, comprising at least the following steps. (A) a step of preparing a first sealed tube in which a pair of discharge electrodes are disposed and a discharge gas is sealed (B) A second sealed tube covering the periphery of the first sealed tube (C) forming a space-adjusting projection at a predetermined position of the second envelope tube, which protrudes from an inner wall of the second envelope tube toward a central axis of the second envelope tube. The first envelope tube is inserted into the second envelope tube so that the space adjustment projection faces the vicinity of the discharge electrode, and the space adjustment projection is inserted into the first envelope tube. Adjusting the dimension between the second envelope tube (d) Evacuating the interior of the second envelope tube to a predetermined ultimate pressure (e) End portion of the first envelope tube and the end A step of melt-bonding the second envelope tube to form an airtight space between the first envelope tube and the second envelope tube;