JP2000331646A - Double tube type discharge tube and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the breakage of a sealed tube by falling, impact or the like by providing a second sealed tube connected between first and second outer tube connection parts and surrounding the circumference of a first sealed tube so as to form an airtight space with the first sealed tube. SOLUTION: A second sealed tube 3 is connected between first and second outer tube connection parts 2P and 2Q to form an airtight space 6 with a first sealed tube 2. In the airtight space 6, a plurality of breakage preventing members 7A-7H are arranged at equal intervals along the longitudinal direction. The breakage preventing members 7A-7H are integrally formed of the same glass material as the second sealed tube 3. Since the breakage preventing members 7A-7H can support the first sealed tube 2 substantially non-movably in the central axial part of the second sealed tube 3 even if a double tube type discharge tube 1 is dropped by mistake, or an unexpected impact is applied thereto, the breakage by the vibration or distortion caused in the first sealed tube 2 can be surely prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double-tube discharge tube capable of obtaining a sufficient luminance in a low-temperature environment, and more particularly to a double-tube discharge tube capable of reliably preventing damage to an inner tube due to a drop, impact, or the like. The present invention relates to a double-tube cold-cathode fluorescent discharge tube and a method for manufacturing the same.

[0002]

2. Description of the Related Art A cold cathode discharge tube has a structure in which a pair of electrodes arranged opposite to each other are surrounded by a single glass tube. In this cold cathode discharge tube, when used in a low temperature environment, the temperature inside the discharge tube does not rise sufficiently, so that the mercury vapor pressure inside the discharge tube decreases and the luminous efficiency decreases, and High emission luminance could not be obtained.

In order to solve such technical problems, a double-tube cold-cathode discharge tube tends to be generally used in a low-temperature environment. FIG. 12 is a sectional structural view of a double-tube cold-cathode discharge tube according to the prior art. The double-tube cold-cathode discharge tube 11 includes an inner tube (light-emitting tube) 12 that hermetically seals a pair of discharge electrodes 14A and 14B that are arranged to face each other, and the inner tube 12 with an airtight space 16 interposed. Outer tube 13 to be covered
And a terminal 15 coupled to each of the pair of discharge electrodes 14A and 14B and led out from inside the inner tube 12 to outside the outer tube 13.
A and 15B.

[0004] An elongated glass tube is used for the inner tube 12,
An elongated glass tube having an inner diameter larger than the outer diameter of the inner tube 12 is used for the outer tube 13, and the inner tube 12 and the outer tube 13 are integrally formed at both ends by fusion bonding. The inner wall of the inner tube 12 is coated with a fluorescent film that emits visible light when irradiated with ultraviolet rays generated by electric discharge. Further, the inside of the inner tube 12 is air-tightly sealed, and neon (Ne) gas and argon (A)
r) A discharge gas composed of a mixed gas with a gas is generally sealed. The discharge gas is usually sealed at a pressure in the range of about 5.3 kPa to 13 kPa. The inside of the outer tube 13 is hermetically sealed similarly to the inside of the inner tube 12, and is kept in a high vacuum state at a pressure in the range of about 133 mPa to 1.3 Pa.
The heat insulation effect of is enhanced.

The double-tube cold-cathode discharge tube 11 configured as described above maintains the hermetic space 6 between the inner tube 12 and the outer tube 13 in a high vacuum state having a low thermal conductivity. Inner tube 12
Is hard to escape to the outside through the outer tube 13 and a sufficient heat insulating effect can be obtained, so that a sufficient light emission luminance can be obtained even in a low temperature environment.

[0006]

However, in the double-tube cold-cathode fluorescent discharge tube 11 shown in FIG. 12, no consideration was given to the following points.

The double-tube cold-cathode fluorescent discharge tube 11 has an inner tube 12 and an outer tube 13 integrally formed by fusion bonding at both ends where a pair of discharge electrodes 14A and 14B are provided. ing. The molten joint portion between the inner tube 12 and the outer tube 13 is a portion indicated by a dashed line with reference numeral 17 in FIG.
Is covered with a thick tube portion 12A of the inner tube 12, and the terminal 15B is covered with a thick tube portion 12B. A pair of discharge electrodes 1
4A and 14B are surrounded by the thin wall portion 12 of the inner tube 12.
12, one end on the left side in FIG. 12 of the thin tube portion 12C is formed integrally with the thick tube portion 12A, and the other right end of the thin tube portion 12C is integrally formed with the thick tube portion 12B. ing. The left end of the outer tube 13 in FIG. 12 is joined to the thick portion 12A of the outer tube 13 in a state where the outer tube 13 extends over the boundary 12D between the thin portion 12C and the thick portion 12A of the inner tube 12. The other end on the right side is a thin tube portion 12C and a thick tube portion 12B of the inner tube 12.
Is joined to the pipe thick part 12B in a state where the pipe thin part 12C overlaps with the boundary 12E.
However, the central portion of the thin wall portion 12C is supported in a floating state. For this reason, when the double-tube cold-cathode fluorescent discharge tube 11 itself or the personal computer to which the double-tube cold-cathode fluorescent discharge tube 11 is attached is accidentally dropped or a strong shock is applied. However, there is a problem in that the thin tube portion 12C of the inner tube 12 vibrates in the outer tube 13 or the thin tube portion 12C bends to damage the inner tube 12.

In particular, one end of the outer tube 13 is joined to the thick portion 12A of the inner tube 12 in a state where the end extends over the boundary 12D between the thin portion 12C and the thick portion 12A of the inner tube 12, and the other end of the outer tube 13 is connected to the other end. Boundary 12E between thin wall 12C and thick wall 12B of inner tube 12
And the inner tube 12 is damaged when the double-tube cold-cathode fluorescent discharge tube 11 is dropped or a strong impact is applied. There were many things. That is, these external forces due to a drop or a strong impact are originally generated from the outer tube 13 by the fusion bonding portion 17.
Through which the thin portion 12C of the inner tube 12 and the root supporting the thin portion 12C (a boundary 12D between the thin portion 12C and the thick portion 12A, a boundary 1 between the thin portion 12C and the thick portion 12B)
2E), the thin wall portion 12C is thin and the root supporting the thin wall portion 12C tends to concentrate stress. In particular, one end of the outer tube 13 is connected to the thin tube portion 12C of the inner tube 12.
The outer tube 13 is connected to the thicker portion 12A of the inner tube 12 at the boundary 12E between the thinner portion 12C of the inner tube 12 and the thicker portion 12B of the inner tube 12 in a state where the outer tube 13 is joined to the thicker portion 12A. If the tube is joined to the thick tube portion 12B in the applied state, distortion remains in the inner tube 12, and this stress concentration tends to occur.

The present invention has been made to solve the above problems.

[0010] Accordingly, an object of the present invention is to provide a double tube type discharge tube capable of reliably preventing damage to the sealed tube due to dropping, impact, or the like. In particular, an object of the present invention is to reliably prevent breakage of the inner tube (first sealing tube) due to dropping, vibration, and the like, and more specifically, damage of the thin tube portion of the inner tube and the portion supporting the thin tube portion. It is an object of the present invention to provide a double-tube discharge tube.

Another object of the present invention is to provide a double tube type discharge tube capable of improving the heat insulating effect and obtaining excellent luminance characteristics in a low temperature environment.

Still another object of the present invention is to provide a method of manufacturing a double tube discharge tube capable of reliably preventing damage due to dropping, vibration, and the like.

Still another object of the present invention is to provide a method of manufacturing a double tube discharge tube capable of improving the heat insulating effect and obtaining excellent luminance characteristics in a low temperature environment. .

[0014]

SUMMARY OF THE INVENTION In order to solve the above problems, a first feature of the present invention is that a first inner pipe connecting portion and a first inner pipe connecting portion which is separated from the first inner pipe connecting portion by a fixed distance. A first electrode sealing portion that partially covers the first electrode terminal so that both ends of the first electrode terminal are exposed, a second inner tube connection portion, and a second inner tube connection portion. A second outer tube connection portion spaced apart from the inner tube connection portion by a predetermined distance, and a second electrode sealing portion covering a part of the second electrode terminal so that both ends of the second electrode terminal are exposed. And a first sealed tube (inner tube) connected between the first and second inner tube connecting portions and filled with a discharge gas therein, and a first and second outer tube connecting portion. And a second envelope tube (outer tube) disposed around the outer periphery of the first envelope tube so as to form an airtight space between the first envelope tube and the first envelope tube. It is that it is a discharge tube. The “first and second inner pipe connection parts” and the “first and second outer pipe connection parts” are actually regions having a certain area. In the double-tube discharge tube according to the first aspect of the present invention, these “connection portions” are ends of a region having a certain area, and include the first sealed tube (inner tube) and the second sealed tube. It means a part that functions as a mechanical fulcrum of the envelope tube (outer tube). "Separate from the inner tube connection by a certain distance" means that the double tube discharge tube itself or an electronic device incorporating the double tube discharge tube is accidentally dropped or a strong impact is applied. In other words, it is used in a sense that the external force applied to the second sealing tube, which is the outer tube, is separated by a predetermined distance so as not to directly reach the inner tube connecting portion. This fixed distance (predetermined distance) is usually a distance measured in the longitudinal direction of the double tube discharge tube.

As described above, in the double tube type discharge tube according to the first aspect of the present invention, the first and second inner tube connection portions are each separated from the first and second inner tube connection portions by a certain distance in the longitudinal direction. The first and second electrode sealing portions are respectively coupled to the second sealing tube at the second outer tube connecting portion. For this reason, the second sealed portion is formed at the boundary between the thin wall portion of the first sealed tube that is easily damaged and the thin wall portion of the first sealed tube where stress concentration is likely to occur and the first and second electrode sealing portions. The external force applied to the body canal can be reduced. That is, even if the double-tube discharge tube itself according to the first feature of the present invention or an electronic device such as a personal computer to which the discharge tube is attached is accidentally dropped or subjected to an impact, 2 through the first and second outer tube connecting portions from the first sealed tube to the first and second sealed tubes.
The external force propagating through the electrode sealing portion in the longitudinal direction through a certain distance in the longitudinal direction, and further transmitted to the first sealing tube via the first and second inner tube connecting portions, is transmitted to the first and second electrode sealing portions. It can be damped at the stop. Therefore, it is possible to effectively prevent vibration or bending that is transmitted from the second envelope tube to the first envelope tube and affects the first envelope tube, and it is possible to reliably prevent the first envelope tube from being damaged. And in the double tube discharge tube according to the first feature of the present invention, the first and second inner tube connection portions are more double tube discharge than the first and second outer tube connection portions. It is preferable to arrange the tube at a position farther (more outer side) than the central axis (in the longitudinal direction) of the tube. This is in contrast to the conventional double tube type discharge tube shown in FIG. 12, in which the inner tube connection portion serving as a mechanical fulcrum is arranged on the inner diameter side of the outer tube connection portion. is there. In this way, by providing a step between the first inner pipe connection and the first outer pipe connection, and between the second inner pipe connection and the second outer pipe connection, the inner portion is provided. The certain distance between the pipe connection and the outer pipe connection can be effectively made longer.
As a result, the external force transmitted from the outer pipe connection to the inner pipe connection can be more effectively attenuated.

In the double tube type discharge tube according to the first aspect of the present invention, it is preferable that the airtight space further includes a plurality of breakage preventing members disposed at equal intervals along a longitudinal direction of the space. . Here, the "breakage preventing member" is to prevent the first envelope tube from being damaged or to prevent the first envelope tube from being vibrated or deflected due to an unexpected impact and from being damaged. For preventing damage. The damage prevention member may be arranged as a set of two at a position rotated by about 180 degrees with respect to the central axis of the first envelope tube, and further, three members may be arranged in the circumferential direction of the second envelope tube. Four or more breakage preventing members may be arranged at equal intervals, and three, four, or more members may form one set. Further, the number of damage prevention members arranged in the circumferential direction is increased, and the damage prevention members are extended to the entire outer peripheral surface of the first sealed tube or the inner circumferential surface of the second sealed tube so as to be mutually continuous extremes. Along the entire surface,
It may be formed in a closed ring. "A plurality of arrangements" means that it is preferable that at least two or more sets are arranged in an airtight space between the first enclosure pipe and the second enclosure pipe. At least one set of the damage prevention members is provided near the central portion in the longitudinal direction between the first discharge electrode and the second discharge electrode so as to prevent vibration or bending of the first sealed tube. It may be arranged. Alternatively, the two sets of breakage preventing members may be arranged in the longitudinal direction between the first discharge electrode and the second discharge electrode so as to be symmetric with respect to the center line between the first discharge electrode and the second discharge electrode. They may be arranged evenly in the vicinity of the central portion, and furthermore, a total of four sets may be evenly arranged including two sets at both ends. As described above, in the double tube discharge tube according to the first aspect of the present invention, the first sealed tube is fixed to the central shaft portion of the second sealed tube by the plurality of breakage preventing members. As a result, the dimensions of the airtight space between the first and second sealing tubes can be kept uniform. A plurality of breakage preventing members are provided between the first discharge electrode and the second discharge electrode (particularly near the center) along the longitudinal direction of each of the first and second sealed tubes. By arranging them at equal intervals,
Vibration and bending generated in the first sealing tube can be dispersed by the plurality of breakage preventing members, and the stress per breakage prevention member can be reduced. Therefore, in addition to the effect obtained by the double-tube discharge tube according to the first feature of the present invention, the double-tube discharge tube itself or an electronic device such as a personal computer to which the double-tube discharge tube is attached is erroneously installed. Even if you drop it or apply an impact,
The first sealing tube can be more effectively supported by the central shaft portion of the second sealing tube through the interposition of the damage prevention member. For this reason, the vibration which propagates to the first envelope tube can be effectively attenuated, and the vibration or bending affecting the first envelope tube can be prevented, so that the breakage of the first envelope tube is surely prevented. be able to. Further, the airtight space (thickness of the airtight space) between the first envelope tube and the second envelope tube can be kept uniform between the discharge electrodes by the plurality of breakage preventing members. In addition, the heat insulating effect can be improved, and particularly, the luminance characteristics in a low temperature environment can be improved.

In the double tube discharge tube according to the first aspect of the present invention, the first and second electrode sealing portions and the second sealing tube are connected to the first and second outer tube connecting portions. Is preferably formed integrally by fusion bonding. That is, since a separate connecting member is not required for coupling the first and second electrode sealing portions and the second sealing tube, and furthermore, for coupling the first sealing tube and the second sealing tube, the number of parts is reduced. Therefore, the structure of the double tube discharge tube can be easily realized.

Similarly, in the double tube type discharge tube according to the first aspect of the present invention, the first and second electrode sealing portions are connected to the first and second electrode sealing portions.
It is preferable that the first and second inner tube connecting portions are integrally formed with the sealing tube by fusion bonding. That is,
Since a separate connecting member is not required for connecting the first and second electrode sealing portions to the first sealing tube, the number of components can be reduced, and the structure of the double tube discharge tube can be simplified. Can be realized.

In this case, the first and second electrode sealing portions are
If each has at least a portion having an outer dimension substantially equal to the inner diameter of the first envelope tube,
The connection between the first and second electrode sealing portions and the first sealing tube is facilitated, and the assembly of the double tube discharge tube is also simplified.

Further, in the double tube type discharge tube according to the first aspect of the present invention, the damage prevention member is formed integrally with the first or second sealed tube, and It is preferable that the tube or the second envelope tube is formed of the same material. That is,
When the first sealing tube or the second sealing tube is formed of a glass material, it is preferable that the breakage preventing member is formed of the same glass material as the first sealing tube or the second sealing tube. In the double-tube discharge tube configured as described above, the damage prevention member is integrally formed of the same material as the first or second envelope tube, so that the number of parts can be reduced. And the structure can be easily realized.

Further, in the double tube type discharge tube according to the first aspect of the present invention, the damage preventing member may be provided from the first sealed tube toward the second sealed tube or from the second sealed tube to the second sealed tube. It is preferable that the projection is formed into a hermetic space so as to protrude toward the first sealed tube and formed in a projecting shape so as to be able to make point contact with the second sealed tube or the first sealed tube. Here, the “projection shape that allows the break prevention member to come into point contact” means the first seal even if the tip portion of the protrusion shape of the break prevention member comes into contact with the first sealed tube or the second sealed tube. It is an expression meaning a shape that makes it difficult for heat of the body tube to escape to the second sealed tube through the damage prevention member. For example, it is practical that the breakage preventing member is formed in any one of a needle shape and a conical protrusion shape. Further, in the double-tube discharge tube according to the first aspect of the present invention, in order to securely hold the first envelope tube at the central axis portion of the second envelope tube, the damage prevention member includes the first envelope tube. Two or more sets may be arranged at equal positions around the envelope tube. The number of damage prevention members may be increased as appropriate according to the length of the double tube discharge tube and the vibration stress applied to the double tube discharge tube. In the double-tube discharge tube configured as described above, it is possible to increase the thermal resistance value of the contact portion when the damage prevention member comes into contact with the first envelope tube or the second envelope tube, 1 Heat of the envelope tube to the second
Since it is difficult to escape to the sealing tube, the heat insulating effect can be improved, and the luminance characteristics can be further improved.

A second feature of the present invention is that (1) one end of a first sealing tube (inner tube) is connected to a first electrode sealing portion at a first inner tube connecting portion, and Connecting the other end of the first sealing tube (inner tube) to the second electrode sealing portion at the tube connection portion;
(2) a step of forming a second envelope tube (outer tube) having a geometrical shape capable of covering the periphery of the first envelope tube;
In the first outer tube connection portion separated from the inner tube connection portion by a certain distance, one end of the second sealed tube and the first electrode sealing portion are fusion-bonded to each other, and Producing a double-tube discharge tube at least comprising a step of fusion-bonding the other end of the second envelope tube and the second electrode sealing portion to each other at a second outer tube connection portion separated by a predetermined distance. That is the way.

According to the method for manufacturing a double tube discharge tube according to the second feature of the present invention, the first and second inner tube connection portions are
In the longitudinal direction, first and second
Since the first and second electrode sealing portions are respectively coupled to the second sealing tube at the outer tube connecting portion, there is little failure such as generation of pinholes at the time of connecting the second sealing tube, and the double tube is connected. Easy assembly of the discharge tube. Furthermore, since the first and second inner pipe connecting portions are located at a certain distance in the longitudinal direction from the first and second outer pipe connecting portions, respectively, the thin wall portion of the first sealed pipe which is easily damaged or In addition, it is possible to reduce the external force applied to the second sealing tube from reaching the boundary between the thin wall portion of the first sealing tube and the first and second electrode sealing portions where stress concentration is likely to occur. That is, even if the double-tube discharge tube itself according to the first feature of the present invention or an electronic device such as a personal computer to which the discharge tube is attached is accidentally dropped or subjected to an impact, 2 through the first and second outer tube connection portions, through the first and second outer tube connection portions, propagate through the first and second electrode sealing portions, and further through the first and second inner tube connection portions, 1
External force transmitted to the sealing tube can be attenuated by the first and second electrode sealing portions.

Further, in the method for manufacturing a double tube type discharge tube according to the second aspect of the present invention, (a) a plurality of breakage preventing devices are provided inside the second sealed tube or outside the first sealed tube. Forming the members at equal intervals along the longitudinal direction thereof, and (b) disposing the first envelope tube inside the second envelope tube, and using the member for preventing damage to the first envelope tube and the first envelope tube. Adjusting the size of the airtight space between the second envelope tube and the first and second envelope tubes.
It is preferable to further perform the process before the step of melting and bonding the electrode sealing portions to each other and forming an airtight space between the first sealing tube and the second sealing tube. With this configuration, when the first sealed tube is disposed inside the second sealed tube, a plurality of damage prevention members formed in advance on the first sealed tube or the second sealed tube serve as positioning members. Thus, the arrangement position of the first sealing tube at the central axis portion of the second sealing tube can be adjusted. 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. Therefore, the manufacturing process of the double tube discharge tube can be simplified (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,
Since the damage and breakage of the sealing tube caused by the spacer mounting operation and the discharging operation can be eliminated, the production yield can be improved. Furthermore, by simplifying the manufacturing process, the manufacturing cost can be reduced. In addition, even if the double tube type discharge tube itself or an electronic device or the like to which the double tube type discharge tube is accidentally dropped or subjected to an impact, the first and second outer tubes are removed from the second envelope tube. The force can be dispersed by the plurality of breakage preventing members at the same time as the damping is performed via the connection portion, so that a double-tube discharge tube that is more resistant to mechanical shock can be provided.

[0025]

Next, first and second embodiments of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, the drawings are schematic,
It should be noted that the relationship between the wall thickness and the length, the ratio of the wall thickness of each tube, and the like are different from actual ones. Therefore, specific thicknesses and dimensions should be determined in consideration of the following description.

(First Embodiment) FIG. 2 shows a first embodiment of the present invention.
FIG. 1 is a cross-sectional structure diagram of a double tube discharge tube (double tube cold cathode fluorescent discharge tube) according to an embodiment of the present invention. FIG. It is. 1 and 2
As shown in (1), the double tube discharge tube 1 according to the first embodiment of the present invention covers a part of the first electrode terminal 5A so that both ends of the first electrode terminal 5A are exposed. The first electrode sealing portion 2A (the left side in FIGS. 1 and 2) and the second electrode terminal 5
A second electrode sealing portion 2B (right side in FIG. 2) that covers a part of the second electrode terminal 5B so that both ends of B are exposed;
A first sealing tube (inner tube) 2 connected between the second electrode sealing portions 2A and 2B and having a discharge gas sealed therein;
It is connected between the first and second electrode sealing portions 2A and 2B, and is arranged so as to surround the outer periphery of the first envelope tube so as to form an airtight space 6 with the first envelope tube 2. And a second sealed tube (outer tube) 3. Here, the first electrode sealing portion 2A includes a first inner tube connecting portion 2D and the first inner tube connecting portion 2D.
And a first outer tube connecting portion 2P which is separated from the inner tube connecting portion 2D in the longitudinal direction by a fixed distance L1. The second electrode sealing portion 2B includes a second inner tube connecting portion 2E and the second inner tube connecting portion 2E. 2 which is separated from the inner pipe connecting portion 2E by a certain distance L2 in the longitudinal direction.
And the outer tube connecting portion 2Q. Therefore, the first sealed tube (inner tube) 2 is composed of the first and second inner tube connecting portions 2D and 2D.
E, and the second envelope tube (outer tube) 3 is connected between the first and second outer tube connection portions 2P and 2Q.
Therefore, the second sealed tube (outer tube) 3 is longer than the first sealed tube (inner tube) by L1 + L2.

A first discharge electrode 4A is provided at one end of the first electrode terminal 5A, and a second discharge electrode 4A is provided at one end of the second electrode terminal 5B.
The discharge electrode 4B is connected, and the first discharge electrode 4A and the second discharge electrode 4B face each other. The first sealing tube (inner tube) 2 surrounds the first discharge electrode 4A and the second discharge electrode 4B, and has one end integrated with the first electrode sealing portion 2A to form the second electrode sealing portion. An airtight space is formed by the thin tube portion 2C having the other end integrated with the portion 2B, and a discharge gas is sealed therein.

Further, the double-tube discharge tube 1 according to the first embodiment of the present invention has a longitudinal section in an air-tight space 6 between the first envelope tube 2 and the second envelope tube 3. Damage prevention members 7A, 7B, 7 provided at equal intervals along the direction
C, 7D, 7E, 7F, 7G, and 7H.

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 1.7 mm. The thin wall portion 2C in the central portion of the first envelope tube 2 is the original thickness of such an elongated tubular sealing tube, and the thickness is, for example, within a range of 0.1 mm to 0.3 mm. Is set. The first electrode sealing portion 2A of the first sealing tube 2 is a portion in which one end is melted in order to hermetically seal the inside of the first sealing tube 2, and is substantially outside the first sealing tube 2. First electrode terminal 5 based on diameter
It is also possible to understand that the thick pipe is thicker than the thin pipe section 2C in the range of, for example, 0.9 mm to 0.6 mm from which the outer diameter of A is subtracted. As shown in FIG. 1, the first electrode sealing portion 2
Since A is formed by melting one end of the first sealing tube 2, the first electrode sealing portion 2A and the thin tube portion 2C are integrally formed (substantially the same glass). The first inner tube connecting portion 2D, which is a boundary between the first electrode sealing portion 2A and the thin tube portion 2C, is a portion where the wall thickness changes rapidly. Second electrode sealing portion 2B of first sealing tube 2
Is a portion in which the other end is melted in order to hermetically seal the inside of the first sealing tube 2 and has the same size and structure as the first electrode sealing portion 2A. Similarly to the first electrode sealing portion 2A, the second electrode sealing portion 2B and the thin tube portion 2C are formed integrally, and the second electrode sealing portion 2B and the thin tube portion 2C are formed integrally. The second inner pipe connecting portion 2E located at the boundary between the two is a portion where the wall thickness changes rapidly.

The second sealing tube 3 is a sealing tube formed of an elongated tubular glass material having an outer diameter of, for example, 2.4 mm to 2.6 mm, which is larger than the outer diameter of the first sealing tube 2. It is. By selecting the outer dimensions of both, the first sealing tube 2 can be disposed inside the second sealing tube 3. Both ends of the first envelope tube 2 and the second envelope tube 3 extend from the first outer tube connecting portion 2P indicated by broken lines in FIGS. Are formed integrally with each other, with each of the second fusion-bonded portions 8B extending from the outer tube connecting portion 2Q.

Then, as shown in FIG. 1 and FIG.
The inner tube connecting portion 2D and the second inner tube connecting portion 2E of the double tube discharge tube 1 (in the longitudinal direction) are better than the first outer tube connecting portion 2P and the second outer tube connecting portion 2Q. It is arranged at a position farther from the center axis (more outer side). This is in contrast to the conventional double tube type discharge tube shown in FIG. 12, in which the inner tube connection portion serving as a mechanical fulcrum is arranged on the inner diameter side of the outer tube connection portion. is there. As described above, steps are provided between the first inner pipe connection 2D and the first outer pipe connection 2P, and between the second inner pipe connection 2E and the second outer pipe connection 2Q. Thus, the fixed distances L1 and L2 are effectively made longer.

The constant distance L1 (offset to the left) measured in the longitudinal direction from the first inner tube connection portion 2D to the first outer tube connection portion 2P is equal to the double tube discharge tube 1 itself or the two tubes. An electronic device (for example, a personal computer) in which the double tube type discharge tube 1 is incorporated is accidentally dropped or a strong impact is applied, and external force applied to the second envelope tube 3 is directly applied to the boundary 2D portion. The distance is shorter than the distance, which varies depending on the physical properties of the glass material, the dimensions of the double tube type discharge tube 1, and the like.
Preferably, it is set to about 0.7 mm.

Further, the constant distance L2 (offset to the right) measured in the longitudinal direction from the second inner pipe connecting portion 2E to the second outer pipe connecting portion 2Q is the same for the same reason as the constant distance L1. Dimensions are set. That is, the first envelope tube 2
The boundary 2D between the first electrode sealing portion 2A and the thin-walled portion 2C of the first electrode 2D so that external force does not reach the boundary 2D (first inner tube connection portion) where mechanical strength is low and stress tends to concentrate. The first sealed tube 2 and the second sealed tube 3 are melt-bonded in a region 8A (a region extending further outward from the first outer tube connecting portion 2P) at a predetermined distance L1 or more outward from the first tube, and likewise, In order to prevent external force from reaching the boundary 2E between the second electrode sealing portion 2B and the thin wall portion 2C of the sealing tube 2 where mechanical strength is low and stress tends to concentrate, the boundary (the second inner portion) is used. The first sealed tube 2 and the second sealed tube 3 are fusion-bonded in a region 8B (a region extending further outward from the second outer tube connecting portion 2Q) away from the pipe connecting portion 2E by a predetermined distance L2 or more. Have been.

As described above, the thin tube portion 2C of the first sealing tube 2
Between first electrode sealing portion 2A and first inner tube connecting portion 2A
The first fusion-bonded portion 8A extending outward from the first outer tube connection portion 2P that is spaced apart from the first outer tube connection portion 2P by a certain distance L1 in the longitudinal direction from the second fusion-bonded portion 2A is second.
One end side of the sealing tube 3 is joined, and a boundary (second inner tube connecting portion) 2E between the thin tube portion 2C and the second electrode sealing portion 2B.
Since the other end side of the second sealing tube 3 is joined by the second fusion joint portion 8B extending outward from the second outer tube connecting portion 2Q which is separated by a predetermined distance L2 in the longitudinal direction from the first sealing member, The thin wall portion 2C where the pipe 2 is easily broken, and the first where the stress concentration is likely to occur.
A boundary (first inner tube connecting portion) 2D between the thin tube portion 2C of the envelope tube 2 and the first electrode sealing portion 2A, and a boundary (first boundary) between the thin tube portion 2C and the second electrode sealing portion 2B. The external force applied to the second sealing tube 3 directly to each of the two inner tube connecting portions 2E can be reduced. Therefore, the double tube type discharge tube 1
Even if the electronic device itself or the electronic device of the personal computer to which it is attached is accidentally dropped or subjected to an impact, the external force transmitted from the second envelope tube 3 to the first envelope tube 2 is not affected. Since it is possible to attenuate (absorb) each of the first electrode sealing portions 2A and 2B of the first sealing tube 2, vibration or bending generated in the first sealing tube 2 and particularly the thin tube portion 2C is prevented. The first envelope tube 2
Can reliably be prevented from being damaged.

Further, the first electrode sealing portion 2A of the first sealing tube 2 and one end of the second sealing tube 3 are integrally formed by fusion bonding to form the second electrode sealing portion 2B and the second electrode sealing portion 2B. By integrally forming the other end of the second sealed tube 3 with the other end of the second sealed tube 3, a separate connecting member is not required for connecting the first sealed tube 2 and the second sealed tube 3, so that the number of parts can be reduced. Therefore, the structure of the double-tube discharge tube 1 can be easily realized.

The size of the airtight space 6 between the first sealing tube 2 and the second sealing tube 3 is about 0.45 mm to 0.6 mm in consideration of the wall thickness from the respective outer diameters. .

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. The inner wall of the second sealing tube 3 has a breakage preventing member 7A.
Basically, the fluorescent film is not applied including the respective surfaces of 7H to 7H. 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.

A pair of first and second discharge electrodes 4A, 4B
Are formed in a cylindrical shape in the first embodiment, and are formed of an electrode material such as nickel (Ni).
The respective electrode shapes of the first and second discharge electrodes 4A and 4B are not particularly limited, but various shapes such as a dish shape, a bar shape, a wire shape, and the like can be adopted.

One end of the first electrode terminal 5A is electrically connected to the discharge electrode 4A, and the other end is led out of the second sealed tube 3. Similarly, one end of the second electrode terminal 5B is electrically connected to the discharge electrode 4B, and the other end is connected to the second electrode terminal 5B.
It is led out of the envelope tube 3. First electrode terminal 5
A and 5B are each formed of a metal material having good electric conductivity such as nickel, for example, between the first electrode terminal 5A and the first discharging electrode 4A, and between the second electrode terminal 5B and the second electrode terminal 5B.
Each of the electrodes is connected to the discharge electrode 4B by, for example, fusion bonding, brazing, soldering, or the like.

The inside of the hermetic space 6 between the first envelope tube 2 and the second envelope tube 3 is maintained in a high vacuum state where 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, an adiabatic gas having poor thermal conductivity (high thermal resistance) such as argon gas, ethylene (CH ₂ = CH ₂ ) gas, ethane (C ₂ H ₆ ) gas, and monoxide Nitrogen (NO) gas, krypton (K
r) Gas or any one of polyhalogenated derivatives such as fluoromethane (CF ₄ , C ₂ F ₆ ) or chlorofluoromethane (CCl ₂ F ₂ ), or a plurality of gases selected from these Can be filled.

In the first embodiment, the breakage preventing members 7A to 7H are formed of the same glass material as the second envelope tube 3 and are formed integrally with the second envelope tube 3. The breakage preventing members 7A to 7H are provided from the inner wall of the second sealed tube 3 toward the first sealed tube 2 (preferably the second sealed tube 3).
(Toward the central shaft portion of the first sealing tube 2), and are arranged (arranged) at equal intervals along the length direction of the first sealing tube 2.

More specifically, a plurality of breakage preventing members 7A-
7H is a fusion bonding portion 8A between one end of the first envelope tube 2 and one end of the second envelope tube 3, and the other end of the first envelope tube 2 and the other end of the second envelope tube 3. Between the first sealing tube 2 and the second sealing tube 3 between the first sealing tube 2 and the second sealing tube 3 at the same distance from each other along the longitudinal direction. Further, the first damage prevention member 7A and the second damage prevention member 7B are similarly positioned at positions facing each other.
The seventh damage prevention member 7E and the sixth damage prevention member 7F are located at positions where the damage prevention member 7C and the fourth damage prevention member 7D face each other. The breakage preventing member 7G and the eighth breakage preventing member 7H are disposed at positions facing each other. That is, the damage prevention members 7A and 7B and the damage prevention member 7 are located at positions rotated by about 180 degrees around the first envelope tube 2 as a central axis.
C and 7D, breakage preventing members 7E and 7F, and breakage preventing members 7G and 7H are provided, respectively. Fused joint 8
A, the distance between the first damage prevention member 7A, the first damage prevention member 7A and the third damage prevention member 7C, the third damage prevention member 7C and the fifth damage prevention member The distance between the member 7E, the distance between the fifth damage preventing member 7E and the seventh damage preventing member 7G, and the distance between the seventh damage preventing member 7G and the fusion joint 8B are all set to be equal. . Similarly, the distance between the fusion-bonded portion 8A and the second damage prevention member 7B, the distance between the second damage prevention member 7B and the fourth damage prevention member 7D, and the distance between the fourth damage prevention member 7D and the fourth damage prevention member 7D The distance between the sixth damage prevention member 7F, the distance between the sixth damage prevention member 7F and the eighth damage prevention member 7H, and the distance between the eighth damage prevention member 7H and the fusion joint 8B Are also set equal.

The thus constructed damage preventing member 7A
７7H means that even if the double-tube discharge tube 1 itself or the equipment to which the double-tube discharge tube 1 is attached is accidentally dropped, or an unexpected impact is applied thereto, At the central axis portion of the second sealing tube 3, the first sealing tube 2
Can be supported so that it does not substantially move,
First envelope tube 2 due to vibration or bending generated in first envelope tube 2
Can reliably be prevented from being damaged.

FIG. 3 is an enlarged sectional structural view of the double-tube discharge tube 1 taken along the line F3-F3 in FIG. The distal end portions of the breakage preventing members 7A to 7H 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 space therebetween. That is, the damage prevention members 7A, 7A
The leading edge of C, 7E, 7G and damage prevention members 7B, 7D,
The dimension between the leading ends of 7F and 7H is set to be substantially the same as the outer dimension of the first envelope tube 2 or slightly larger than the outer dimension of the first envelope tube 2. .

As shown in FIG. 3, each of the breakage preventing members 7A and 7B disposed on the upper side and the lower side of the second sealing tube 3 so as to face each other, vibrates or bends. The first envelope tube 2 is supported from above and below so that the tube 2 does not move (do not cause breakage). Although not shown in FIG. 3, as shown in FIG. 2 described above, the damage preventing members 7C and 7D, 7E and 7
Similarly, each of F, 7G, and 7H supports the first envelope tube 2 from above and below so that the first envelope tube 2 does not move due to vibration or bending. Therefore, the double tube type discharge tube 1
Alternatively, even if the electronic device to which the double-tube discharge tube 1 is attached is accidentally dropped or a strong impact is given from the outside, the first sealed tube 2 inside the second sealed tube 3 The first enclosure tube 2 can be reliably prevented from being damaged without causing large vibration or bending.

The tip portions of the damage preventing members 7A to 7H are formed in such a shape that they make point contact when they come into contact with the outer peripheral surface of the first envelope tube 2. In FIGS. 2 and 3, the tip portions of the breakage preventing members 7A to 7H are formed in a conical shape. However, in the first embodiment of the present invention, these breakage preventing members 7A to 7H are formed. 7
The shape of the tip of H may be formed in another shape such as a needle shape.

In the double-tube discharge tube 1 according to the first embodiment of the present invention as described above, the first sealed tube 2
A constant distance L1 in the longitudinal direction from the first inner tube connecting portion 2D located at the boundary between the thin tube portion 2C and the first electrode sealing portion 2A.
In the first outer tube connecting portion 2P separated from the first outer tube connecting portion 2P, the first electrode sealing portion 2A and one end side of the second sealing tube 3 are fusion-bonded. Similarly, the second inner tube connecting portion 2E located at the boundary between the thin wall portion 2C of the first sealing tube 2 and the second electrode sealing portion 2B.
In the second outer tube connecting portion 2Q that is separated from the second outer tube connecting portion 2Q by a certain distance L2 in the longitudinal direction, the second electrode sealing portion 2B and the second sealing tube 3
Is melt-bonded to the other end side of the first sealing tube 2, the thin wall portion 2 </ b> C of the first sealing tube 2 which is easily broken, and the boundary 2 </ b> D and the boundary 2 </ b> E of the first sealing tube 2 where stress concentration tends to occur. The external force applied to the second sealing tube 3 can be reduced from being directly applied. As a result, even if the double-tube discharge tube 1 itself or an electronic device or the like to which the double-tube discharge tube 1 is attached is dropped or a strong impact is applied to the double-tube discharge tube 1, the second sealing member is not removed. Since the external force transmitted from the tube 3 to the first envelope tube 2 can be attenuated by each of the first electrode sealing portions 2A and 2B of the first envelope tube 2, the first envelope tube 2, especially the tube Vibration or bending affecting the thin portion 2C can be prevented, and breakage of the first sealing tube 2 can be reliably prevented. Therefore, it is possible to prevent the double tube type discharge tube 1 from being damaged or the electronic device from being damaged.

Further, in the double tube type discharge tube 1 according to the first embodiment of the present invention, the first electrode sealing portion 2A and the second sealing tube 3 of the first sealing tube 2 are connected. The first sealing tube 2 and the second sealing tube 3 are integrally formed by fusion bonding, and the second electrode sealing portion 2B and the second sealing tube 3 are integrally formed by fusion bonding. Since a separate connecting member is not required for connecting to the discharge tube, the number of parts can be reduced,
Can be easily realized.

Further, in the double tube discharge tube 1 according to the first embodiment of the present invention, the first sealed tube 2 is provided by the breakage preventing members 7A to 7H provided on the second sealed tube 3. Has been dropped from above and below, and the double-tube discharge tube 1 itself or an electronic device or the like to which the double-tube discharge tube 1 has been attached has been dropped, or a strong impact has been applied thereto. Even in this case, the first sealing tube 2 can be prevented from vibrating or flexing inside the second sealing tube 3 by the breakage preventing members 7A to 7H. Can be prevented from being damaged. As a result, breakage of the double tube type discharge tube 1 or breakage of electronic equipment and the like can be prevented.

Further, in the double tube type discharge tube 1 according to the first embodiment of the present invention, the members 7A to 7A for preventing breakage are provided.
H functions as a member for adjusting the hermetic space, and the dimension of the hermetic space 6 (thickness of the hermetic space 6) between the first envelope tube 2 and the second envelope tube 3 is determined by the total length of the first envelope tube 2. , The heat insulating effect of the hermetic space 6 can be improved, and the luminance characteristics can be maintained stably especially in a low temperature environment.

Further, in the double tube type discharge tube 1 according to the first embodiment of the present invention, the damage prevention members 7A to 7H 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.

Next, a method for manufacturing the double-tube discharge tube 1 according to the first embodiment of the present invention will be briefly described with reference to process sectional views shown in FIGS.

(1) First, a fluorescent film is applied to the inner wall using a well-known glass cutting technique, a glass shield technique, or the like.
Both ends of a glass tube 2C formed of a thin tube portion, a first electrode sealing portion 2A that partially covers the first electrode terminal 5A so that both ends of the first electrode terminal 5A are exposed, and both ends of a second electrode terminal 5B are formed. The second electrode terminal 5B is partially covered so as to be exposed.
Is prepared. A first discharge electrode 4A is connected to one end of the first electrode terminal 5A, and a second discharge electrode 4B is connected to one end of the second electrode terminal 5B. And FIG.
As shown in (1), one end of the first sealing tube (inner tube) 2C is connected to the first electrode sealing portion 2A at the first inner tube connecting portion 2D, and the first inner tube connecting portion 2E is connected to the first inner tube connecting portion 2E. Seal tube (inner tube)
The other end of 2C is connected to the second electrode sealing portion 2B. At this time, a discharge gas is sealed inside the first sealed tube 2.
As a result, a pair of discharge electrodes 4A and 4B are arranged inside the first envelope tube 2, and the first electrode terminals 5A and 5B are led out from inside to outside.

(2) In order to form the second sealed tube 3, a glass tube 3A shown in FIG. 5 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. 5 are open.

(3) Next, as shown in FIG. 6, the glass tube 3A is placed at a predetermined position on the glass tube 3A serving as the second sealing tube 3.
A plurality of breakage preventing members 7A to 7H protruding from the inner wall of the glass tube toward the central axis of the glass tube 3A are formed. here,
The “predetermined position” means that after completion of the double tube type discharge tube 1, the damage prevention members 7A to 7H are melt-bonded to the respective melt-bonded portions 8A and 8A of the first sealed tube 2 and the second sealed tube 3. 8B (refer to FIG. 2). The predetermined position is the fusion joint 8A
If the distance between and the fusion bonding portion 8B is measured in advance, it can be easily estimated, or can be easily estimated (designed) from design data.

These breakage preventing members 7A to 7H are formed, for example, by heating and melting a predetermined portion of the glass tube 3A with a gas burner, and projecting the heated and melted portion with a pin having a predetermined stroke. Due to the stroke of the pin, the height of the damage prevention members 7A to 7H from the inner peripheral surface of the glass tube 3A is substantially equal to the size of the airtight space 6 (thickness of the airtight space 6) shown in FIGS. The leading edge height of the inwardly protruding breakage preventing members 7A to 7H can be adjusted to be the same or slightly lower. As described above, the dimension between the forefront of each of the damage prevention members 7A, 7C, 7E, and 7G and the forefront of each of the breakage prevention members 7B, 7D, 7F, and 7H is the first envelope tube 2 Can be set to a size substantially the same as or slightly larger than the external dimensions of.
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 of (a) is drawn inside, and the members 7A to 7H
May be formed.

(4) As shown in FIG. 7, the first sealed tube 2 is inserted into the glass tube 3A while utilizing the plurality of damage preventing members 7A to 7H formed as described above. Then, the first sealing tube 2 is disposed inside the glass tube 3A. Here, the first sealing tube 2 is provided with breakage preventing members 7A to 7H.
Is inserted into and disposed in the glass tube 3A while being brought into contact with the tip of the glass tube 3A, so that the disposition position of the first sealing tube 2 is automatically adjusted at a substantially central portion of the glass tube 3A. That is, the size of the airtight space 6 between the first sealing tube 2 and the second sealing tube 3 shown in FIGS. 2 and 3 is automatically and uniformly adjusted.

(5) As shown in FIG. 8, at the first outer tube connecting portion 2P separated from the first inner tube connecting portion 2D by a fixed distance L1 (offset to the left), the glass tube 3
One end of A (second sealing tube) and the first electrode sealing portion 2A are fusion-bonded to each other. Specifically, the first outer tube connecting portion 2P
In the region extending outward from the first electrode sealing portion 2A
And one end of the glass tube 3A by fusion to form a fusion joint 8A (shown by a broken line in FIG. 8), 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 evacuation device such as a turbo-molecular pump, a cryopump, an oil diffusion pump, and the like. 133mPa ~ 1.3m
Set the background pressure (ultimate pressure) to about Pa.

(7) The internal pressure of the glass tube 3A is 133 mPa or more.
When the pressure in the range of 1.3 mPa is reached, the exhaust is stopped,
While maintaining this internal pressure, as shown in FIG.
At a position enclosing the electrode sealing portion 2B and the second electrode terminal 5B, the glass tube 3C is heated using a gas burner, and the other end of the glass tube (second sealing tube) 3A is melt-bonded. As a result, the inside of the glass tube (second sealed tube) 3A is sealed off to a vacuum.

(8) Then, using a gas burner, at the second outer tube connecting portion 2Q separated from the second inner tube connecting portion 2E by a fixed distance L2 (offset to the right), the second sealing member is formed. The other end of the tube 3A and the second electrode sealing portion 2B are fusion-bonded to each other. Specifically, the second outer tube connecting portion 2
In a region 8B extending outward from Q (see FIG. 1), the second electrode sealing portion 2B and the other end of the glass tube 3A are joined by melting. As a result, as shown in FIG. 1 described above, the second sealed tube 3 is formed from the glass tube 3A. Then, an extra glass tube 3A is cut off. The double-tube discharge tube 1 according to the first embodiment is completed through a series of these manufacturing steps.

In the method of manufacturing the double-tube discharge tube 1 according to the first embodiment of the present invention described above,
When disposing the first sealing tube 2 inside the second sealing tube 3, the first sealing tube 2 is formed by the damage prevention members 7A to 7H formed in advance on the glass tube 3A (the second sealing tube 3). Position can be automatically adjusted. Therefore, when arranging the first sealing tube 2 inside the second sealing tube 3, a manufacturing jig such as a spacer is not separately required. Can be eliminated, thereby simplifying the manufacturing process of the double tube discharge tube 1 (reducing the number of manufacturing processes).
be able to. In addition, since complicated control operations of the manufacturing jig such as the mounting process and the removing process of the manufacturing jig can be eliminated, automation of the manufacturing of the double tube discharge tube 1 can be realized. Furthermore, since the first sealing tube 2 and the second sealing tube 3 can be prevented from being damaged or broken due to the mounting operation and the removing operation of the manufacturing jig, the manufacturing yield can be improved. . Furthermore, by simplifying the manufacturing process, the manufacturing cost can be reduced.

Further, in the method of manufacturing the double tube type discharge tube 1 according to the first embodiment of the present invention, the glass tube 3A
Since the members 7A to 7H for preventing damage of the (second sealing tube 3) can be formed by partial heating and melting using a gas burner, the members 7A to 7H for preventing damage can be easily formed, and production can be performed. Performance can be improved.

In the above description of the first embodiment of the present invention, the damage prevention members 7A to 7H are formed as a set of two at a position rotated by about 180 degrees with respect to the center axis of the first envelope tube 2. Although the case where it arrange | positioned was demonstrated, three, four or more damage prevention members are arranged at equal intervals in the circumferential direction of the 2nd sealing pipe 3, and three, four or more As one set, at least two or more sets may be arranged at equal intervals along the longitudinal direction of the pair of discharge electrodes. Further, the number of damage prevention members arranged in the circumferential direction is increased, and as a limit which is continuous with each other, as shown in FIG. 2 may be formed in a closed annular shape along the entire area of the inner peripheral surface of the sealing tube 3). The cross-sectional shape of the closed annular damage preventing member 7A may be substantially triangular or the like, and may have a small contact area at the time of contact.

(Second Embodiment) A second embodiment is similar to the double-tube discharge tube according to the first embodiment described above, except that the first and second inner tube connecting portions are connected to each other. This is a structure in which a second sealing tube (outer tube) is connected to first and second outer tube connecting portions which are separated (offset) by a certain distance in the longitudinal direction. However, unlike the double tube type discharge tube according to the first embodiment, an example in which a damage preventing member is provided on the first envelope tube side will be described. FIG. 11 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. 11 has an airtight space 6 between a first fusion joint 8A and a second fusion joint 8B.
In the inside, a plurality of breakage preventing members 9A to 9H are provided at equal intervals along the longitudinal direction, and are provided in the first envelope tube 2 so as to protrude into the airtight space 6. The damage prevention members 9A to 9H are all provided on the outer peripheral surface of the first sealing tube 2. In a second embodiment of the present invention,
Each of the damage preventing members 9A to 9H is formed of the same glass material as the first sealing tube 2. The breakage preventing members 9A to 9H are obtained by attaching a glass material separately prepared from the first envelope tube 2 to the outer peripheral surface of the first envelope tube 2 by fusion bonding.

In the double tube type discharge tube 1 according to the second embodiment, the tube of the first sealed tube 2 is similar to the double tube type discharge tube 1 according to the first embodiment. A first outer tube connecting portion 2 which is separated from a boundary (first inner tube connecting portion) 2D between the thin portion 2C and the first electrode sealing portion 2A by a certain distance L1 in the longitudinal direction.
At P, the first electrode sealing portion 2A and one end of the second sealing tube 3 are fusion-bonded. Similarly, a boundary (second inner tube connecting portion) 2 between the thin tube portion 2C and the second electrode sealing portion 2B.
At a second outer tube connecting portion 2Q which is separated from E by a certain distance L2 in the longitudinal direction, the second electrode sealing portion 2B and the other end side of the second sealing tube 3 are fusion-bonded. For this reason, each of the thin wall portion 2C of the first sealing tube 2 that is easily damaged, the boundary portion (first inner pipe connection portion) 2D where stress concentration is likely to occur, and the boundary (second inner pipe connection portion) E Furthermore, the external force applied to the second sealing tube 3 is reduced from being directly applied.

In the double-tube discharge tube 1 according to the second embodiment of the present invention as described above, the first tube of the present invention
The same effect as in the double-tube discharge tube 1 according to the embodiment can be obtained. Furthermore, the dimensions of the glass material forming the separately provided damage prevention members 9A to 9H are previously unified, so that the damage prevention members 9A to 9H having a uniform height on the outer peripheral surface of the first envelope tube 2. Can be easily attached, the breakage of the first envelope tube 2 can be easily prevented, and the position adjustment (airtightness) between the first envelope tube 2 and the second envelope tube 3 in manufacturing can be performed. The accuracy of (the thickness of the space 6) can be easily improved.

As a modification of the second embodiment of the present invention, a glass tube having break prevention members 9A to 9H arranged at regular intervals and protruding toward the hermetic space 6 on the outer peripheral surface is provided as a modification. May be used to configure the first envelope tube 2. In this case, there is no need to perform a step of melt-bonding the glass materials for the damage prevention members 9A to 9H to the first envelope tube 2.

Further, the damage preventing members 9A to 9H are
In the circumferential direction of the sealing tube 3, three, four or more breakage preventing members are arranged at equal intervals, and three, four or more members are arranged as a set to form a pair of discharge electrodes. At least two or more sets may be arranged at regular intervals along the longitudinal direction. Further, the number of damage prevention members arranged in the circumferential direction increases, and as a limit that is continuous with each other, the damage prevention members are connected to the outer peripheral surface (or the 2 may be formed in a closed annular shape along the entire area of the inner peripheral surface of the sealing tube 3). The cross-sectional shape of the closed annular damage prevention member may be substantially triangular or the like so as to have a small contact area at the time of contact.

(Other Embodiments) Although the present invention has been described with reference to the 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 first and second embodiments described above, both sides of the first sealing tube 2 and both sides of the second sealing tube 3 are respectively connected by fusion bonding. In the above, both the first sealing tube 2 and the second sealing tube 3 can be connected via a holding member formed of a separate member.

In the first embodiment (or the second embodiment), the upper surface of the second sealing tube 3 is provided between the first fusion joint 8A and the second fusion joint 8B. The four damage prevention members 7A, 7C, 7E and 7G
Four damage prevention members 7B, 7D, 7F and 7 on the lower surface side
Although a total of eight damage prevention members 7A to 7H of H are formed, a smaller number or a larger number of damage prevention members may be formed.

In this case as well, the space between adjacent damage preventing members on the upper surface side or the lower surface side, the space between the damage preventing member and the fusion joint 8A, and the distance between the damage prevention member and the fusion joint 8B. Are set equal to each other.
This makes it possible to effectively disperse and reduce vibrations and deflections that propagate to the first sealing tube 2.

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 invention specifying matters according to the appropriate claims.

[0076]

According to the present invention, it is possible to provide a double tube type discharge tube capable of reliably preventing breakage due to vibration or bending of the sealed tube due to dropping, impact or the like. In particular, according to the present invention, it is possible to provide a double-tube discharge tube capable of reliably preventing damage to the inner tube (first envelope tube) due to dropping, vibration, or the like.

Further, according to the present invention, it is possible to provide a double tube discharge tube capable of improving the heat insulation effect and obtaining excellent luminance characteristics under a low temperature environment.

Further, according to the present invention, it is possible to provide a manufacturing method capable of easily manufacturing a double-tube discharge tube having a structure capable of reliably preventing breakage due to an impact or the like.

Further, according to the present invention, there is provided a manufacturing method capable of manufacturing a double-tube discharge tube capable of obtaining excellent luminance characteristics under a low temperature environment at a low cost and a high manufacturing yield. Can be.

[Brief description of the drawings]

FIG. 1 is an enlarged cross-sectional structural view of a main part of a double-tube discharge tube according to a first embodiment of the present invention along a longitudinal direction.

FIG. 2 is a sectional structural view along a longitudinal direction of the double tube discharge tube according to the first embodiment of the present invention.

FIG. 3 is an enlarged sectional view taken along a line perpendicular to the longitudinal direction of the double-tube discharge tube according to the first embodiment of the present invention (an enlarged sectional view taken along section line F3-F3 in FIG. 2); Figure).

FIG. 4 is a process sectional view of the double-tube discharge tube according to the first embodiment of the present invention (part 1).

FIG. 5 is a process sectional view of the double-tube discharge tube according to the first embodiment of the present invention (part 2).

FIG. 6 is a process sectional view of the double-tube discharge tube according to the first embodiment of the present invention (part 3).

FIG. 7 is a process sectional view of the double-tube discharge tube according to the first embodiment of the present invention (part 4).

FIG. 8 is a process sectional view of the double-tube discharge tube according to the first embodiment of the present invention (part 5).

FIG. 9 is a process sectional view of the double-tube discharge tube according to the first embodiment of the present invention (part 6).

FIG. 10 is a sectional structural view of a double-tube discharge tube according to a modification of the first embodiment of the present invention, taken perpendicular to the longitudinal direction.

FIG. 11 is a cross-sectional structural view along a longitudinal direction of a double tube discharge tube according to a second embodiment of the present invention.

FIG. 12 is a cross-sectional structural view along a longitudinal direction of a double-tube cold-cathode fluorescent discharge tube according to the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Double tube discharge tube 2 1st sealed tube (inner tube) 2A 1st electrode sealing part 2B 2nd electrode sealing part 2C Tube thin part 2D 1st inner tube connection part 2E 2nd inner Tube connection portion 2P First outer tube connection portion 2Q Second outer tube connection portion 3 Second envelope tube (outer tube) 3A Glass tube 4A First discharge electrode 4B Second discharge electrode 5A First electrode terminal 5B Second electrode terminal 6 Hermetic space 7A to 7H, 9A to 9H Damage prevention member 8A First fusion joint 8B Second fusion joint

Claims (9)

[Claims] A first inner tube connecting portion and a first outer tube connecting portion separated from the first inner tube connecting portion by a predetermined distance so that both ends of the first electrode terminal are exposed; A first electrode sealing portion that covers a part of the first electrode terminal, a second inner tube connecting portion, and a second outer tube connecting portion that is separated from the second inner tube connecting portion by a certain distance. A second electrode sealing portion that covers a part of the second electrode terminal so that both ends of the second electrode terminal are exposed, and is connected between the first and second inner tube connection portions; A first sealing tube in which a discharge gas is sealed, and connected between the first and second outer tube connecting portions; and
In order to form an airtight space between the first sealing tube and the first sealing tube,
A double-tube discharge tube, comprising: a second envelope tube surrounding the outer periphery of the envelope tube. 2. The double-tube discharge according to claim 1, further comprising a plurality of breakage preventing members disposed at equal intervals along a longitudinal direction in the airtight space. tube. 3. The first electrode sealing portion and the second sealing tube are fusion-bonded at the first outer tube connecting portion, and the second electrode sealing portion and the second sealing member are joined together. 3. The double-tube discharge tube according to claim 1, wherein the tube and the second outer tube connection portion are fusion-bonded and integrally formed. 4. 4. The first electrode sealing portion and the first sealing tube are fusion-bonded at the first inner tube connecting portion, and the second electrode sealing portion and the first sealing member are joined together. The double-tube discharge tube according to any one of claims 1 to 3, wherein the tube is melt-bonded at the second inner tube connection portion and is integrally formed. 5. The first and second electrode sealing portions each have at least a portion having an outer dimension substantially equal to the inner diameter of the first sealing tube. Item 5. The double tube discharge tube according to any one of Items 1 to 4. 6. The damage preventing member is formed integrally with the first or second sealing tube, and is formed of the same material as the first or second sealing tube. The double-tube discharge tube according to any one of claims 2 to 5, wherein: 7. The breakage preventing member projects into the hermetic space from the first envelope tube toward the second envelope tube or from the second envelope tube toward the first envelope tube. Sealed tube or first
The double-tube discharge tube according to any one of claims 2 to 6, wherein the double-tube discharge tube is formed in a projection shape so as to be able to make point contact with the envelope tube. 8. A method for producing a double tube discharge tube, comprising at least the following steps. (1) One end of the first sealed tube is connected to the first electrode sealing portion at the first inner tube connecting portion, and the other end of the first sealed tube is connected to the second inner tube connecting portion at the second inner tube connecting portion. (2) Step of forming a second envelope tube having a geometric shape capable of covering the periphery of the first envelope tube (3) Connection of the first inner tube At a first outer tube connection portion separated by a certain distance from the portion, one end of the second sealing tube and the first electrode sealing portion are fusion-bonded to each other, and are fixed from the second inner tube connection portion. A step of melt-bonding the other end of the second sealing tube and the second electrode sealing portion to each other at a second outer tube connecting portion separated by a distance; 9. An airtight space between the first sealing tube and the second sealing tube, wherein the second sealing tube and the first and second electrode sealing portions are fusion-bonded to each other. 9. The method for manufacturing a double tube discharge tube according to claim 8, further comprising the following step before the step of forming a discharge tube. (B) A step of forming a plurality of breakage preventing members at equal intervals along the longitudinal direction inside the second sealed tube or outside the first sealed tube. Arranging a first sealing tube inside the body tube and adjusting a size of an airtight space between the first sealing tube and the second sealing tube by the damage preventing member;