JP2008218215A - Discharge lamp, back light unit, liquid crystal display, and manufacturing method of discharge lamp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a discharge lamp in which slow leakage and cracks are harder to be generated than conventional ones, and its manufacturing method. <P>SOLUTION: This is the discharge lamp in which a discharge medium is sealed in a discharge space in the envelope tube formed by sealing both ends of a cylindrical glass tube. At least one sealing part 7 of the envelope tube is a sealing body having a columnar outward protruding part 17 protruding outward to the opposite side to the discharge space in a tube axis 13 direction from the end part of a straight tube part of nearly the same cross sectional shape over the whole length, and a columnar inward protruding part 16 protruding in the discharge space without contacting the straight tube part 15 directly is connected with the straight tube part 15. Outer diameters D2, D3 of the outward protruding part 17 and the inward protruding part 16 are smaller than the inner diameter D1 of the glass tube. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a discharge lamp in which a discharge medium is sealed in a discharge space in an outer tube formed by sealing both ends of a cylindrical glass tube, a backlight unit using the discharge lamp as a light source, and the backlight The present invention relates to a liquid crystal display including a unit and a method for manufacturing the discharge lamp, and more particularly to a technique for sealing a glass tube in a manufacturing process of the discharge lamp.

In recent years, the spread of large-sized liquid crystal televisions is remarkable, and the demand for direct-type backlight units (hereinafter referred to as “LCBL units”) used in these large-sized liquid crystal televisions is increasing.
As a light source for the LCBL unit, a mercury discharge lamp is generally used. However, in order to simultaneously turn on a plurality of these lamps, the same number of high-frequency electronic ballasts as the number of lamps is required. The application of is being considered.

  Here, since a plurality of dielectric barrier discharge lamps (Patent Document 1) can be lit by, for example, one high frequency electronic ballast, they are suitable as light sources for LCBL units using as many as 16 lamps, for example. If there are variations in the electrical characteristics such as the capacitance of the electrode portion, uneven brightness and the like are not preferable. Therefore, it is necessary to make the shape of the external electrode portion substantially uniform.

The sealing portion at the end of the conventional dielectric barrier discharge lamp includes a first method in which the end of the glass tube is heated and melted and the glass tube itself is bent and deformed in the tube center direction, and the end of the glass tube is sealed. Insert cylindrical glass beads into the through-holes of the part, heat the outer peripheral surface of the glass bead end facing the glass bead, and melt and seal the inner peripheral surface of the glass tube end and the outer peripheral surface of the glass bead It is manufactured by one of the second methods.
JP 2003-229092 A

  However, in the first method, since the glass tube itself is bent and deformed in the tube center direction, the suction to the discharge space side is intense, and it is difficult to control the amount of deformation, so the tube length at the time of completion tends to vary. In addition, there is a problem that the shape of the tube end portion is not stable and is easily distorted, and further, a slow leak may occur near the tube center at the tube end portion, resulting in poor yield. Here, the slow leak means that a capillary having a small diameter is generated when the tube end portion melted in the glass sealing is solidified, and air enters the discharge space from the capillary, and is sealed later. It tends to occur on the edge side.

  On the other hand, in the second method, since glass beads are used, the deformation of the tube end during sealing is reduced, and the shape of the tube end is stabilized as shown in FIG. However, when forming an external electrode by applying molten solder to the end, cracks due to thermal shock may occur at the junction with the glass tube in the vicinity of the discharge space side end of the glass beads, and the yield is increased. There is a problem of getting worse. The inventors have discovered that in the dielectric barrier discharge lamp sealed by the second method, an acute groove 90 is formed at the welded portion between the glass beads and the glass tube on the discharge space side. I thought that it might be the cause of the problem of cracks due to thermal shock.

  The present invention has been made in view of the above problems, and is a discharge lamp in which slow leaks and cracks are unlikely to occur and the end shape is stable, a backlight unit using the discharge lamp as a light source, and the backlight It is an object of the present invention to provide a liquid crystal display device including a unit and a method for manufacturing the discharge lamp.

  In order to achieve the above object, a discharge lamp according to the present invention is a discharge lamp in which a discharge medium is sealed in a discharge space in an envelope formed by sealing both ends of a cylindrical glass tube. The at least one end of the envelope tube is a circle protruding outward in the tube axis direction opposite to the discharge space with respect to the end portion of the straight tube portion having substantially the same cross-sectional shape over the entire length. A sealing body having a columnar outward projecting portion and a cylindrical inward projecting portion projecting into the discharge space without directly contacting the straight tube portion, is connected to the straight tube portion; and The outer diameter of the outward protrusion and the inward protrusion is smaller than the inner diameter of the glass tube.

In order to achieve the above object, a backlight unit according to the present invention uses the discharge lamp as a light source.
In order to achieve the above object, a liquid crystal display according to the present invention is characterized in that the discharge lamp is used as a light source of a backlight unit.
In order to achieve the above object, a discharge lamp manufacturing method according to the present invention includes a discharge medium enclosed in a discharge space in an outer tube formed by sealing both ends of a cylindrical glass tube in a reduced pressure state. A method of manufacturing a discharge lamp comprising: sealing one end of the outer tube, sealing the other end of the glass tube, and temporarily fixing a sealing body to the one end. Then, after the inside of the glass tube is in a reduced pressure state, the discharge space side in the sealing body is heated together with the glass tube through the glass tube, and the discharge space side in the sealing body is first set to the glass. It is characterized by being fused to a tube.

  According to the configuration of the discharge lamp, the backlight unit, and the liquid crystal display described in the means for solving the problem, at least one end portion of the discharge lamp is opposite to the end portion of the straight tube portion and opposite to the discharge space side. Since there is a protruding part on both sides, that is, since a sealing body such as glass beads is used, the end part deformation of the straight pipe part can be reduced, and the length of the pipe at the time of completion is less likely to occur In addition, since the vicinity of the tube center is thick at the end portion, it is difficult for a slow leak to occur near the tube center, and the outer diameter of the outer protrusion and the inner protrusion is smaller than the inner diameter of the glass tube. Because the inward projecting part does not directly contact the straight pipe part and the sharp groove is not formed in the welded part as in the past, cracks due to thermal shock occur at the joint part. There.

Therefore, the yield is improved.
Here, in the discharge lamp, the backlight unit, and the liquid crystal display, the thickness of the connecting portion that connects the straight tube portion and the sealing body is substantially equal to the thickness of the straight tube portion. By doing so, heat is uniformly applied to the straight tube portion and the connecting portion, and cracks are unlikely to occur.

  Here, in the discharge lamp, the backlight unit, and the liquid crystal display, at least one end portion of the envelope tube is formed by fusing and sealing the glass tube and the sealing body, The outward projecting portion and the inward projecting portion are mainly portions where the sealing body is thermally deformed, the straight tube portion is a portion where the glass tube is not thermally deformed, and the connecting portion is Since the glass tube is mainly a thermally deformed portion, cracks are hardly generated in the thermally deformed portion.

Here, in the discharge lamp, the backlight unit, and the liquid crystal display, at least one end portion of the envelope tube is formed by fusing and sealing the glass tube and the sealing body, The inward protruding portion may be characterized in that the sealing body is mainly drawn into the discharge space by a negative pressure.
Thereby, compared with the case where the sealing body is not used at the end of the tube, the vicinity of the tube center is thick, so that a slow leak near the center of the tube is less likely to occur. Since it does not contact, the shape of the end is stable, and cracks due to thermal shock at the joint are unlikely to occur.

Further, the discharge lamp manufacturing method described in the means for solving the problem uses a sealing method having a sealing body such as glass beads in sealing one end, so that the tube length after sealing Is difficult to vary and the shape is stable.
Also, since the vicinity of the tube center is thicker than when no sealing body is used at the tube end, a slow leak near the tube center is less likely to occur, and furthermore, the protruding portion does not directly contact the straight tube portion. The shape of the end is stable and cracks due to thermal shock at the joint are unlikely to occur.

Therefore, the yield is improved.
Here, in the method for manufacturing a discharge lamp, after the discharge space side of the sealing body is first welded to the glass tube, the sealing body is drawn into the discharge space side by negative pressure, and the discharge By forming the inward projecting portion projecting into the space, the glass density at the center portion of the tube axis increases, and it is difficult for slow leaks to occur.

[Embodiment 1]
<Overview>
Embodiment 1 of the present invention is a heating position in the step of sealing the end of a cylindrical tube with a sealing body (bead / glass beads) when manufacturing a mercury discharge lamp having an electrode on the outer periphery. In the straight part and the connecting part, there is little unevenness in the thickness of each, and it is possible to stabilize the shape, reduce the occurrence rate of cracks due to thermal shock in the process of forming the electrode, and improve the yield. It is to improve.

<Configuration>
The mercury discharge lamp of the present invention includes, for example, a cold cathode fluorescent lamp (hereinafter referred to as “CCFL”) and an external electrode fluorescent lamp (dielectric barrier discharge lamp: hereinafter referred to as “EEFL”). Etc., which are mainly used in a backlight unit of a liquid crystal display (lamp inner diameter is 1 mm to 8 mm, glass thickness is preferably about 0.2 mm to 0.7 mm). In this embodiment, EEFL is used as an example. Explained. Note that the present invention can be similarly applied to CCFLs and other discharge lamps.

FIG. 1 is a diagram showing an outline of a liquid crystal television according to Embodiment 1 of the present invention.
A liquid crystal television 100 shown in FIG. 1 is, for example, a 32-inch liquid crystal television, and includes a liquid crystal screen unit 101 and a backlight unit 102.
The liquid crystal screen unit 101 includes a color filter substrate, a liquid crystal, a TFT substrate, a drive module and the like (not shown), and forms a color image based on an image signal from the outside.

The backlight unit 102 is an LCBL unit and includes one high-frequency electronic ballast 103 and 16 dielectric barrier discharge lamps 10.
The high-frequency electronic ballast 103 is a lighting circuit that lights all the 16 dielectric barrier discharge lamps 10.
FIG. 2 is a diagram showing an outline of the dielectric barrier discharge lamp 10 according to Embodiment 1 of the present invention.

A dielectric barrier discharge lamp 10 shown in FIG. 2 includes an outer tube 1, a discharge medium 2 sealed in a discharge space in the outer tube 1 in a reduced pressure state, and external electrodes on the outer periphery near both ends of the outer tube 1. 3 and 4, and a phosphor layer 5 is formed on the inner periphery of the outer tube 1.
The envelope tube 1 is made of glass having a diameter of 4 mm, an inner diameter of 3 mm, and a tube length of 730 mm, and may be a tubular glass tube made of lead-free glass (a straight tube having substantially the same cross-sectional shape over the entire length). ) Are sealed and formed, and the sealing portion 6 which is the side to be sealed first is sealed by beadless sealing, and the sealing portion 7 which is the side to be sealed later Is sealed by bead sealing.

  Here, beadless sealing in the sealing portion 6 uses a method similar to the conventional method, but bead sealing in the sealing portion 7 uses a unique method as in the present embodiment. Conventionally, the lower position of the sealing body is heated and sealed with the end to be sealed down, whereas in the present invention, the sealing body 26 (refer to the description of <Manufacturing method> below). 4 and 5 described above are heated, and the upper side of the sealing body 26 is first described in FIGS. 4 and 5 referred to in the description of the <Manufacturing method> below. ) Is fused and sealed to the inner wall, and the upper part of the part where the cylindrical tube 22 and the sealing body 26 are fused is bent in the direction of the tube axis over the entire circumference, which is an unprecedented structural A unique shape of this embodiment is realized. A detailed description of the sealing process of the envelope 1 will be described later.

The discharge medium 2 is the same as the conventional discharge medium, and is composed of, for example, a neon / argon mixed gas having a composition (Ne + Ar 5%), and is sealed together with mercury in the discharge space in the outer tube 1 under reduced pressure. About 8 kPa.
The external electrodes 3 and 4 are conductors provided on the outer periphery near both ends of the outer tube 1. For example, after the discharge medium 2 is sealed and both ends of the cylindrical tube 22 are sealed, the silver containing glass frit is contained. The paste is applied to the area to be formed by screen printing, etc., fired, the surface is polished to improve the adhesion of the solder, and the solder is coated by a dipping method soaking in molten solder, or a metal cap is put on It is formed by filling the gap with solder or winding a metal tape.

The phosphor layer 5 is a wavelength-converting phosphor applied to the inner surface of the envelope 1. For example, a blue phosphor is europium-activated barium magnesium aluminate [BaMg ₂ Al ₁₆ O ₂₇ : Eu ²⁺ ]. (Abbreviation: BAM-B), green phosphor is cerium / terbium co-activated lanthanum phosphate [LaPO ₄ : Ce ³⁺ , Tb ³⁺ ] (abbreviation: LAP) and red phosphor is europium activated yttrium oxide [Y ₂ O ₃ : Eu ³⁺ ] (abbreviation: YOX).

In order to suppress the reaction between glass, phosphor, and mercury and prolong the life, between the envelope 1 and the phosphor layer 5 or between the phosphor layer 5 and the discharge medium 2. A protective layer made of, for example, yttrium oxide (Y ₂ O ₃ ), silica (SiO ₂ ), alumina (Al ₂ O ₃ ), or the like may be provided on the phosphor layer 5.
3 shows the dielectric barrier discharge lamp 10 according to the present embodiment in which the discharge portion 2 is sealed and both ends of the cylindrical tube 22 are sealed, and the sealing portion 7 before forming the external electrodes 3 and 4 is elongated. It is a figure which shows the cross section cut | disconnected in the direction from the center in parallel with the tube wall.

  As shown in FIG. 3, the sealing portion 7 includes a fusion portion 11 in which the cylindrical tube 22 and the sealing body 26 are fused, and a bent portion 12 closer to the center of the tube than the fusion portion 11. Is bent in the direction of the tube axis 13, and has a substantially flat portion 14 (a flat surface on both the outer side and the inner side of the tube) between the fused portion 11 and the bent portion 12. And the inner angle α of the bent portion 12 formed by the cylindrical tube 22 is a substantially right angle of 90 ± 20 degrees.

  In addition, the sealing portion 7 is not deformed by the sealing and is substantially the same shape as the glass tube before sealing, and the end portion of the straight tube portion 15 having the same cross-sectional shape over the entire length (around the bent portion 12). ), There is an inward protruding portion 16 in which the sealing body 26 protrudes in the discharge space (tube center side), which is the discharge space side (tube center side) of the cylindrical tube 22 and the sealing body 26. After the position is heated and fused for the first time, the inside of the tube is in a depressurized state, so that the central cavity 33 of the sealing body 26 (in FIGS. 4 and 5 referred to in the description of the <Manufacturing method> below) This is considered to be formed by the sealing body 26 being drawn into the discharge space (side of the tube) by the negative pressure.

Here, the straight tube portion 15 is a portion where the glass tube before sealing, which was originally a straight tube, is not deformed by heat at the time of sealing, and the inward projecting portion 16 is mainly formed by the sealing body 26. It is a portion deformed by heat at the time of sealing.
And when this sealing body 26 is drawn in and the inward protrusion part 16 is formed, since the cylindrical pipe | tube 22 of the vicinity of the fusion | melting part 11 is softened by heating, it bends suitably and the bending part 12 changes. It seems to be formed.

  Therefore, the inward projecting portion 16 does not directly contact the straight tube portion 15, and a connecting portion (fused portion 11 + substantially flat portion 14 + bent portion 12) that connects them is formed. Since the glass tube before sealing, which was originally a straight tube, is a portion deformed by heat at the time of sealing, the thickness of the connecting portion is substantially equal to the thickness of the straight tube portion 15.

  In addition, the sealing portion 7 protrudes outward (on the side opposite to the tube center) opposite to the discharge space with respect to the end portion of the straight tube portion 15 (around the bent portion 12). There is a side projection 17, which is considered to be the residue of the cylindrical tube 22 covering the lower sealing body 26 that was not drawn into the discharge space, and the sealing body 26 is mainly sealed. It is a part deformed by heat at the time of stopping.

  Here, if the inner diameter of the straight tube portion 15 is D1, the outer diameter of the inward projecting portion 16 is D2, and the outer diameter of the outer projecting portion 17 is D3, the relations D1> D2 and D1> D3 are established. Preferably, in order to obtain a stable bend, D2> D3 and (D1 × 0.5) ≦ D2 ≦ (D1 × 0.9). That is, in the case of D2 <(D1 × 0.5), the amount of the sealing body 26 drawn is increased, and the problem that the dimensional stability in the tube axis direction is deteriorated is likely to occur, and (D1 × 0). .9) In the case of <D2, since the substantially flat portion 14 is short, the variation amount of the internal angle α of the bent portion 12 due to the variation in the amount by which the sealing body 26 is drawn increases, so the internal angle α is partially obtuse. Therefore, a glass tube that is fragile and easily broken can be formed, and the problem that the yield decreases is likely to occur.

In this embodiment, the outward projecting portion 17 has a substantially bullet shape composed of a hemispherical tip portion and a cylindrical body portion, but the shape differs depending on the material of the glass, the temperature of the manufacturing process, etc. For example, it may be substantially hemispherical or spherical.
<Manufacturing method>
4 and 5 are diagrams showing an outline of the sealing process of the envelope tube 1.

Hereinafter, the sealing process of the outer tube 1 will be described with reference to FIGS. 4 and 5.
(1) A cylindrical tube 22 having a phosphor layer 21 coated on the inner surface is prepared, and held in a jig with the longitudinal direction vertical (step A in FIG. 4).
(2) With the metal rod 23 having an outer diameter slightly smaller than the inner diameter of 3.0 mm of the cylindrical tube 22 inserted from the lower end of the cylindrical tube 22, the metal rod 23 is rotated while rotating the cylindrical tube 22 around the tube axis. The outer periphery of the cylindrical tube 22 in the vicinity of the tip is heated by the burners 24 and 25, and the metal rod 23 is gradually moved downward (step B in FIG. 4).

(3) First, the cylindrical tube 22 near the tip of the metal rod 23 is heated and softened, and adheres to the vicinity of the tip of the metal rod 23. Thereafter, as the metal rod 23 moves downward, the cylindrical tube 22 is pulled downward by the metal rod 23, and further, after the portion melted by heating is broken off, and then the molten glass is rounded by surface tension. The lower end is sealed (step C in FIG. 4).
(4) After cooling, the cylindrical tube 22 whose lower end is sealed is turned upside down and held by a jig, and a hollow cylindrical sealing body 26 is placed on the tip of a metal insertion rod 27 so that the cylindrical tube 22 It inserts from a lower end (process D of FIG. 4). Here, the outer shape of the sealing body 26 is an outer diameter of 2.7 mm, an inner diameter of 1.05 mm, and a height of 2 mm.

(5) A part of the outer periphery of the cylindrical tube 22 near the center of the sealing body 26 is heated by the burners 28 and 29, and a part of the sealing body 26 is fused to the inner peripheral surface of the cylindrical tube 22 for sealing. The body 26 is temporarily fixed (step E in FIG. 4).
(6) The cylindrical tube 22 to which the sealing body 26 is temporarily fixed is turned upside down and held by a jig, and a mercury pellet 30 in which mercury is impregnated into a titanium-tantalum-iron sintered body is charged, and a discharge medium Is temporarily sealed by heating the upper end of the cylindrical tube 22 with the burners 31 and 32. Here, since the inside of the tube of the cylindrical tube 22 is in a reduced pressure state, the softened portion is crushed to the atmospheric pressure and merged and temporarily sealed by heating the upper end from the left and right (step F in FIG. 5). ).

(7) The mercury pellet 30 in the tube is induction-heated using a high-frequency oscillation coil (not shown) to evaporate the mercury and diffuse the mercury so that it reaches the space where the discharge space has a low temperature (see FIG. 5). Step G).
(8) The temporarily sealed cylindrical tube 22 is turned upside down and held on a jig, and the cylindrical tube 22 is sealed while rotating the cylindrical tube 22 around the tube axis while the mercury pellet 30 is separated from the sealing body 26. The upper end of the adherend 26 (the end position on the side previously sealed in step C) is heated by the burners 34 and 35 together with the cylindrical tube 22 through the cylindrical tube 22, and the upper end of the sealant 26 is first It fuse | fuses to the inner wall of the cylindrical tube 22 (process H of FIG. 5).

  (9) When the heating is continued after the upper end of the sealing body 26 is fused to the inner wall of the cylindrical tube 22, the inside of the cylindrical tube 22 is in a reduced pressure state, so that the softened cylindrical tube 22 and the sealing body 26 The portion is crushed to atmospheric pressure, and the central cavity 33 of the sealing body 26 is blocked by more than half in the tube axis direction, and then the sealing body 26 is disposed on the inner side of the tube (the side previously sealed in step C). Is drawn (step I in FIG. 5). Here, the heating position may be gradually moved downward.

  (10) When the sealing body 26 is retracted, it is further sealed above the portion of the cylindrical tube 22 that is first fused to the upper end (discharge space side) of the sealing body 26 (first sealed in step C). Since the cylindrical tube 22 on the other side is also softened by heating, the cylindrical tube 22 is bent as appropriate. Further, after the portion melted by heating is cut off and cut off, the sealing body 26 is not drawn into the tube. The lower portion and the remaining portion of the cylindrical tube 22 are melted and rounded by surface tension, the sealing process is completed, and the process proceeds to the formation of the external electrode (process J in FIG. 5).

<Comparison with conventional products>
In the sealing process of the conventional external electrode type discharge lamp, in the process corresponding to process H in FIG. 5 of the present application, the lower end of the sealing body (the end position opposite to the previously sealed side in process C) is heated. Then, the molten cylindrical tube and the sealing body are integrally sealed.
FIG. 8 shows a conventional external electrode type discharge lamp in which a discharge medium is sealed and both ends of a cylindrical tube are sealed before sealing an end of a cylindrical tube before sealing with a sealing body. It is a figure which shows the cross section which cut | disconnected the part in the longitudinal direction from the center in parallel with the tube wall.

  As shown in FIG. 8, the sealing portion on the side to be sealed later using the sealing body in the conventional external electrode type discharge lamp has an irregular shape and unevenness in the thickness. The internal angle of the portion that will correspond to the bent portion 12 of the first embodiment of the present application is clearly smaller and sharper than that of the present application, and the portion that will correspond to the bent portion 12 in the conventional sealing process. It seems that it is extremely difficult to keep the inner angle or the outer angle within 90 ± 20 degrees on average as in the present application.

  The sealing part of the external electrode type discharge lamp before forming the external electrode of the present application as shown in FIG. 3, and the sealing part of the external electrode type discharge lamp before forming the conventional external electrode as shown in FIG. As a result of applying 10 pieces each to a solder layer at 250 ° C. for 3 seconds and comparing the occurrence rate of cracks, in the conventional product, all 10 pieces were cracked, and the occurrence rate of cracks was 100%. On the other hand, in the external electrode type discharge lamp of the present application, no cracks were generated in 10 pieces, and the occurrence rate of cracks was zero.

Similarly, as a result of comparing the occurrence rate of the problem that air enters into the discharge space due to slow leaks, cracks, etc., all the 20 conventional products had the problem and the rate was 100%. On the other hand, in the external electrode type discharge lamp of the present application, no such defect occurred in 20 lamps, and the occurrence rate was zero.
[Modification 1]
<Overview>
In the first modification of the present invention, the case of CCFL will be described.

<Configuration>
FIG. 6 is a diagram showing an outline of the cold cathode fluorescent lamp 50 in Modification 1 of the present invention.
The cold cathode fluorescent lamp 50 shown in FIG. 6 includes an outer tube 51, a discharge medium 2 sealed in a discharge space in the outer tube 51 in a decompressed state, a power supply terminal 53 on the outer periphery near both ends of the outer tube 51, 54 and internal electrodes 58 and 59 in the discharge space, and the phosphor layer 5 is formed on the inner periphery of the outer tube 1.

  The outer tube 51 is made of glass having a diameter of 4 mm, an inner diameter of 3 mm, and a tube length of 730 mm, and may be a cylindrical glass tube made of lead-free glass (a straight tube having substantially the same cross-sectional shape over the entire length). ) Are sealed, and the sealing portion 56 which is the side to be sealed first is sealed by beadless sealing and the sealing portion 57 which is the side to be sealed later. Is sealed by bead sealing.

  Here, beadless sealing in the sealing portion 56 uses the same method as in the prior art, but bead sealing in the sealing portion 57 uses a unique method as in the sealing portion 7 of the first embodiment. Conventionally, the lower end position of the sealing body integrated with the internal electrode 59 is heated and sealed with the end portion to be sealed down, whereas in this modification, the first embodiment and Similarly, the upper position of the sealing body 69 (not shown. Similar to the sealing body 26 described in FIGS. 4 and 5 referred to in the description of the <Manufacturing method> of Embodiment 1) is heated. The inner wall of the cylindrical tube 68 (not shown; similar to the cylindrical tube 22 described in FIG. 4 and FIG. 5 referred to in the description of <Manufacturing method> of the first embodiment) is first placed on the upper side of the sealing body 69. The portion above the portion where the cylindrical tube 68 and the sealing body 69 are fused is bent in the direction of the tube axis over the entire circumference, thereby stabilizing the structure unprecedented. A unique shape of this modification is realized.

The power supply terminals 53 and 54 are connection conductors provided on the outer periphery in the vicinity of both ends of the outer tube 51, and are formed by the same method as the external electrodes 3 and 4 of the first embodiment.
The internal electrodes 58 and 59 are conventional electrodes unique to the CCFL that are electrically connected to the power supply terminals 53 and 54, respectively.
FIG. 7 shows the sealing portion 57 in the longitudinal direction before forming the power supply terminals 53 and 54 in the cold cathode fluorescent lamp 50 of this modification in a state where the discharge medium 2 is sealed and both ends of the cylindrical tube 68 are sealed. It is a figure which shows the cross section cut | disconnected in parallel with the pipe wall from the center.

  As shown in FIG. 7, the sealing portion 57 includes a fusion portion 61 in which a cylindrical tube 68 and a sealing body 69 are fused, and a bent portion 62 closer to the center of the tube than the fusion portion 61. Is bent in the direction of the tube axis 63, and has a substantially flat portion 64 (a flat surface on both the outer side and the inner side of the tube) between the fused portion 61 and the bent portion 62. According to actual measurement, the inner wall of the substantially flat portion 64 And the inner angle β of the bent portion 62 formed by the cylindrical pipe 68 is a substantially right angle of 90 ± 20 degrees.

  In addition, the sealing portion 57 is not deformed by the sealing and is substantially the same shape as the glass tube before sealing, and the end portion of the straight tube portion 65 having the same cross-sectional shape over the entire length (around the bent portion 62). ), There is an inward protruding portion 66 in which the sealing body 69 protrudes in the discharge space (tube center side), which is the discharge space side (tube center side) of the cylindrical tube 68 and the sealing body 69. After the position is heated and fused for the first time, the inside of the tube is in a depressurized state, so it is thought that it is formed by the sealing body 69 being drawn into the discharge space (side of the tube) by the negative pressure. It is.

Here, the straight tube portion 65 is a portion where the glass tube before sealing, which was originally a straight tube, is not deformed by heat at the time of sealing, and the inward protruding portion 66 is mainly formed by the sealing body 69. It is a portion deformed by heat at the time of sealing.
And when this sealing body 69 is drawn in and the inward protrusion part 66 is formed, since the cylindrical pipe | tube 68 of the vicinity of the fusion | melting part 61 is softened by heating, it bends suitably and the bending part 62 is changed. It seems to be formed.

Therefore, the inward projecting portion 66 does not directly contact the straight tube portion 65, and a connecting portion connecting them is formed, and this connecting portion is mainly a glass tube before sealing that was originally a straight tube. Is a portion deformed by heat at the time of sealing, the thickness of the connecting portion is substantially equal to the thickness of the straight tube portion 65.
Further, the sealing portion 57 protrudes outward from the end of the straight tube portion 65 (around the bent portion 62) outwardly from the discharge space (opposite the tube center). There is a side projection 67, which is considered to be the residue of the cylindrical tube 68 covering the lower sealing body 69 that was not drawn into the discharge space, and the sealing body 69 is mainly sealed. It is a part deformed by heat at the time of stopping.

  Here, if the inner diameter of the straight tube portion 65 is D4, the outer diameter of the inward protruding portion 66 is D5, and the outer diameter of the outer protruding portion 67 is D6, the relationship of D4> D5 and D4> D6 is established. Preferably, in order to obtain a stable bend, D5> D6 and (D4 × 0.5) ≦ D5 ≦ (D4 × 0.9). That is, in the case of D5 <(D4 × 0.5), the amount of the sealing body 69 that is pulled in is increased, and the problem that the dimensional stability in the tube axis direction is deteriorated easily occurs, and (D4 × 0 .9) In the case of <D5, since the substantially flat portion 64 is short, the variation amount of the internal angle β of the bent portion 62 due to the variation in the amount by which the sealing body 69 is drawn increases, and therefore the internal angle β is partially obtuse. Therefore, a glass tube that is fragile and easily broken can be formed, and the problem that the yield decreases is likely to occur.

In addition, the shape of the outward protrusion 67 may differ depending on the material of the glass, the temperature at the time of manufacture, and the like, and may be, for example, a substantially hemispherical shape or a substantially spherical shape.
Moreover, even if the tube shape of the envelope tube 1 and the envelope tube 51 is a bent tube having a shape such as “L-shaped”, “U-shaped”, and “U-shaped”, the present application can be similarly applied. Further, the cross section of the glass tube is not limited to a circle, and for example, the cross section may be a flat shape such as an ellipse or a circular long hole. In the case of a flat tube having a flat cross-section of the glass tube, only the shape of the cross-section of the glass tube of the electrode portion may be substantially circular, and the shape of the cross-section of the glass tube of the electrode portion is also A flat shape may be used over the entire length of the glass tube.

Various types of glass can be used for the glass tube and the sealing body. From the viewpoint of reducing stress during sealing, the glass tube and the sealing body are made of the same material or expanded. It is desirable to use materials with similar coefficients.
For example, borosilicate glass, lead glass, lead-free glass, soda glass, or the like may be used for the glass tube and the sealing body. In this case, the dark startability can be improved. That is, the glass as described above contains a large amount of alkali metal oxide typified by sodium oxide (Na ₂ O). For example, in the case of sodium oxide, the sodium (Na) component elutes on the inner surface of the glass bulb over time. To do. This is because sodium has a low electronegativity, and sodium eluted at the inner end of the glass bulb (without a protective film) is considered to contribute to the improvement of the dark startability.

In particular, in the external electrode type fluorescent lamp formed so as to cover the outer electrode on the outer peripheral surface of the glass bulb end, the alkali metal oxide content in the glass bulb material is preferably 3 mol% or more and 20 mol% or less.
For example, when the alkali metal oxide is sodium oxide, the content is preferably 5 mol% or more and 20 mol% or less. If it is less than 5 mol%, the probability that the dark start time will exceed 1 second increases (in other words, if it is 5 mol% or more, the probability that the dark start time will be within 1 second increases), and if it exceeds 20 mol%, the probability increases. This is because the use of time causes problems such as blackening (browning) or whitening of the glass bulb, resulting in a decrease in luminance, and a reduction in strength of the glass bulb.

In consideration of protection of the natural environment, it is preferable to use lead-free glass. However, lead-free glass may contain lead as an impurity in the manufacturing process. Therefore, glass containing lead at an impurity level of 0.1 wt% or less is also defined as lead-free glass.
Further, when the sealing member is made of Dumet, it is preferably in the vicinity of 94 × 10 ⁻⁷ [K ⁻¹ ]. In this case, the thermal expansion coefficient of glass can be made into said range by making the sum total of the alkali-metal component and alkaline-earth metal component in glass into 20 [mol%]-30 [mol%].

Further, it is possible to absorb ultraviolet rays of 254 [nm] or 313 [nm] by doping a glass with a predetermined amount of a transition metal oxide depending on its kind. Specifically, for example, in the case of titanium oxide (TiO ₂ ), the composition ratio of 0.05 [mol%] or more is doped to absorb ultraviolet rays of 254 [nm], and the composition ratio is 2 [mol%] or more. Thus, it is possible to absorb ultraviolet rays of 313 [nm]. However, when titanium oxide is doped more than the composition ratio of 5.0 [mol%], the glass is devitrified, so the composition ratio is 0.05 [mol%] or more and 5.0 [mol%] or less. It is preferable to dope in the range.

In the case of cerium oxide (CeO ₂ ), 254 [nm] ultraviolet rays can be absorbed by doping at a composition ratio of 0.05 [mol%] or more. However, when cerium oxide is doped more than 0.5 [mol%], the glass is colored, so cerium oxide has a composition ratio of 0.05 [mol%] to 0.5 [mol%]. It is preferable to dope in the following range. In addition, since coloring of glass by cerium oxide can be suppressed by doping tin oxide (SnO) in addition to cerium oxide, cerium oxide can be doped to a composition ratio of 5.0 [mol%] or less. . In this case, if cerium oxide is doped with a composition ratio of 0.5 [mol%] or more, ultraviolet rays of 313 [nm] can be absorbed. However, even in this case, when the composition ratio of cerium oxide is more than 5.0 [mol%], the glass is devitrified.

In the case of zinc oxide (ZnO), ultraviolet rays of 254 [nm] can be absorbed by doping at a composition ratio of 2.0 [mol%] or more. However, when zinc oxide is doped more than 10 [mol%], the thermal expansion coefficient of the glass increases, and when the sealing member is made of tungsten (W), the thermal expansion coefficient of the sealing member (about 44 × 10 ⁻⁷ [K ⁻¹ ]) and the glass have a coefficient of thermal expansion, which makes sealing difficult. Therefore, zinc oxide is contained in the range of 2.0 [mol%] to 10 [mol%]. It is preferable to dope. However, when the sealing member is made of Koval or molybdenum (Mo), the thermal expansion coefficient (about 51 × 10 ⁻⁷ [K ⁻¹ ]) of the sealing member is larger than that of tungsten. Therefore, zinc oxide can be doped to a composition ratio of 14 [mol%] or less. Further, when zinc oxide is doped more than 20 [mol%], the glass may be devitrified, so that zinc oxide is in the range of 2.0 [mol%] to 20 [mol%]. It is preferable to dope.

Further, in the case of iron oxide (Fe ₂ O ₃ ), 254 [nm] ultraviolet rays can be absorbed by doping at a composition ratio of 0.01 [mol%] or more. However, when iron oxide is doped more than the composition ratio of 2.0 [mol%], the glass is colored, so the iron oxide is contained in the composition ratio of 0.01 [mol%] to 2.0 [mol%]. It is preferable to dope in the following range.

  The infrared transmittance coefficient indicating the water content in the glass is preferably adjusted to be in the range of 0.3 to 1.2, particularly 0.4 to 0.8. When the infrared transmittance coefficient is 1.2 or less, it becomes easy to obtain a low dielectric loss tangent applicable to a high voltage application lamp such as an external electrode fluorescent lamp (EEFL) or a long cold cathode fluorescent lamp, and 0.8 or less. If so, the dielectric loss tangent becomes sufficiently small and can be applied to a high voltage application lamp.

The infrared transmittance coefficient (X) can be expressed by the following formula.
[Formula 1] X = (log (a / b)) / t
a: Transmittance [%] of a minimum point in the vicinity of 3840 [cm ⁻¹ ]
b: Transmittance [%] of a minimum point in the vicinity of 3560 [cm ⁻¹ ].
t: Thickness of glass Moreover, the structure of the fluorescent substance layer 5 is not limited to said structure, For example, the thing of the following structures can also be used. In this case, including the above materials, the blue phosphor is in the range of 430 (nm) to 460 (nm), the green phosphor is in the range of 510 (nm) to 530 (nm), the red phosphor Have emission peaks in the range of 600 (nm) to 780 (nm).
(1) UV absorption For example, in recent years, with the increase in size of liquid crystal color televisions, polycarbonate having good dimensional stability has been used for the diffusion plate that closes the opening of the backlight unit. This polycarbonate is easily deteriorated by ultraviolet rays having a wavelength of 313 (nm) emitted from mercury. In such a case, a phosphor that absorbs ultraviolet rays having a wavelength of 313 (nm) may be used. Examples of phosphors that absorb ultraviolet rays of 313 (nm) include the following.
(A) Blue europium / manganese co-activated barium aluminate / strontium / magnesium [Ba _1-xy Sr _x Eu _y Mg _1-z Mn _z Al ₁₀ O ₁₇ ] or [Ba _1-xy Sr _x Eu _{y Mg 2-z Mn z Al} 16 O 27]
Here, x, y, and z are preferably numbers satisfying the conditions of 0 ≦ x ≦ 0.4, 0.07 ≦ y ≦ 0.25, and 0 ≦ z <0.1, respectively.

Examples of such phosphors include europium activated barium magnesium aluminate [BaMg ₂ Al ₁₆ O ₂₇ : Eu ²⁺ ], [BaMgAl ₁₀ O ₁₇ : Eu ²⁺ ] (abbreviation: BAM-B), and europium attached. There are active barium aluminate / strontium / magnesium [(Ba, Sr) Mg ₂ Al ₁₆ O ₂₇ : Eu ²⁺ ], [(Ba, Sr) MgAl ₁₀ O ₁₇ : Eu ²⁺ ] (abbreviation: SBAM-B), and the like.
(B) Green • Manganese inactive magnesium gallate [MgGa ₂ O ₄ : Mn ²⁺ ] (abbreviation: MGM)
Manganese activated cerium aluminate, magnesium, zinc [Ce (Mg, Zn) Al ₁₁ O ₁₉ : Mn ²⁺ ] (abbreviation: CMZ)
Terbium-activated cerium aluminate / magnesium [CeMgAl ₁₁ O ₁₉ : Tb ³⁺ ] (abbreviation: CAT)
Europium / manganese co-activated barium aluminate / strontium / magnesium [Ba _1-xy Sr _x Eu _y Mg _1-z Mn _z Al ₁₀ O ₁₇ ] or [Ba _1-xy Sr _x Eu _y Mg _{2 -z} Mn _z Al ₁₆ O _27]
Here, x, y and z are numbers satisfying the conditions of 0 ≦ x ≦ 0.4, 0.07 ≦ y ≦ 0.25, and 0.1 ≦ z ≦ 0.6, respectively, and z is 0.4 It is preferable that ≦ x ≦ 0.5.

Examples of such phosphors include europium / manganese co-activated barium aluminate / magnesium [BaMg ₂ Al ₁₆ O ₂₇ : Eu ²⁺ , Mn ²⁺ ], [BaMgAl ₁₀ O ₁₇ : Eu ²⁺ , Mn ²⁺ ] (abbreviation) : BAM-G), europium / manganese co-activated barium aluminate / strontium / magnesium [(Ba, Sr) Mg ₂ Al ₁₆ O ₂₇ : Eu ²⁺ , Mn ²⁺ ], [(Ba, Sr) MgAl ₁₀ O ₁₇ : Eu ²⁺ , Mn ²⁺ ] (abbreviation: SBAM-G).
(C) Red • Europium activated phosphorus • Yttrium vanadate [Y (P, V) O ₄ : Eu ³⁺ ] (abbreviation: YPV)
Europium activated yttrium vanadate [YVO ₄ : Eu ³⁺ ] (abbreviation: YVO)
Europium-activated yttrium oxysulfide [Y ₂ O ₂ S: Eu ³⁺ ] (abbreviation: YOS)
1 Manganese-activated magnesium fluoride germanate [3.5MgO · 0.5MgF ₂ · GeO ₂ : Mn ⁴⁺ ] (abbreviation: MFG)
Dysprosium-activated yttrium vanadate [YVO ₄ : Dy ³⁺ ] (red and green two-component phosphor, abbreviation: YDS)
In addition, you may mix and use the fluorescent substance of a different compound with respect to one type of luminescent color. For example, only BAM-B (absorbs 313 nm) in blue, LAP (does not absorb 313 nm) and BAM-G (absorbs 313 nm) in green, YOX (does not absorb 313 nm) and YVO in red. A phosphor (absorbing 313 nm) may be used. In such a case, as described above, the phosphor that absorbs the wavelength 313 (nm) is adjusted so that the total weight composition ratio is larger than 50%, so that the ultraviolet ray almost leaks out of the glass tube. Can be prevented. Therefore, when the phosphor layer 105 includes a phosphor that absorbs ultraviolet rays of 313 [nm], deterioration due to ultraviolet rays such as a diffusion plate made of polycarbonate (PC) that closes the opening of the backlight unit is suppressed, The characteristics as a backlight unit can be maintained for a long time.

  Here, “absorbing ultraviolet rays of 313 (nm)” means an excitation wavelength spectrum near 254 (nm) (excitation wavelength spectrum means that excitation light is emitted while changing the wavelength of the phosphor, and the excitation wavelength and emission intensity are changed. It is defined that the intensity of the excitation wavelength spectrum of 313 (nm) is 80 (%) or more, where the intensity is plotted (100). That is, the phosphor that absorbs ultraviolet rays of 313 (nm) is a phosphor that can absorb ultraviolet rays of 313 (nm) and convert it into visible light.

(2) High color reproduction Liquid crystal display devices typified by liquid crystal color televisions have been used as a light source for a backlight unit of the liquid crystal display device in accordance with the recent high color reproduction that is performed as part of the improvement in image quality. There is a need to expand the reproducible chromaticity range in cathode fluorescent lamps and external electrode fluorescent lamps.

  In response to such a request, for example, by using the following phosphor, the chromaticity range can be expanded as compared with the case of using the phosphor in the embodiment. Specifically, in the CIE 1931 chromaticity diagram, the chromaticity coordinate value of the phosphor for high color reproduction includes a triangle formed by connecting the chromaticity coordinate values of the three phosphors used in the embodiment. Located at the coordinates that expand the reproduction range.

In addition, the chromaticity coordinate value of the phosphor (powder) described below is rounded off to the fourth decimal place after the value measured with a spectroscopic analysis device (MCPD-7000) manufactured by Otsuka Electronics Co., Ltd. It is a thing. Moreover, this chromaticity coordinate value is a representative value in each phosphor material, and may show a slightly different value due to a measurement method (measurement principle) or the like.
(A) Blue • Europium activated strontium chloroapatite [Sr ₁₀ (PO ₄ ) ₆ Cl ₂ : Eu ²⁺ ] (abbreviation: SCA), chromaticity coordinates: x = 0.153, y = 0.030
In addition to the above, europium-activated strontium, calcium, barium, chloroapatite [(Sr, Ca, Ba) ₁₀ (PO ₄ ) ₆ Cl ₂ : Eu ²⁺ ] (abbreviation: SBCA) can also be used, and the wavelength 313 (nm) SBAM-B, which can absorb the ultraviolet rays, can also be used for high color reproduction.

(B) Green BAM-G, chromaticity coordinates: x = 0.136, y = 0.572
CMZ, chromaticity coordinates: x = 0.164, y = 0.722
CAT, chromaticity coordinates: x = 0.284, y = 0.635
Terbium / manganese co-activated cerium aluminate / magnesium [CeMgAl ₁₁ O ₁₉ : Tb ³⁺ , Mn ²⁺ ] (abbreviation: CAM), chromaticity coordinates: x = 0.256, y = 0.657
Manganese-activated zinc silicate [Zn ₂ SiO ₄ : Mn ²⁺ ] (abbreviation: ZSM), chromaticity coordinates: x = 0.248, y = 0.700
As described above, these can also absorb ultraviolet rays having a wavelength of 313 (nm), and besides the three phosphor particles described here, MGM can also be used for high color reproduction.

(C) Red • YOS, chromaticity coordinates: x = 0.658, y = 0.330
YVO, chromaticity coordinates: x = 0.661, y = 0.328
MFG, chromaticity coordinates: x = 0.708, y = 0.288
As described above, these can also absorb ultraviolet rays having a wavelength of 313 (nm), and besides the three phosphor particles described here, YPV and YDS can also be used for high color reproduction.

  In addition, the chromaticity coordinate values shown above are representative values measured only with each phosphor powder, and due to the measurement method (measurement principle), etc., the chromaticity coordinates indicated by each phosphor powder The value may be slightly different from the value listed above. For reference, the chromaticity coordinate values of the phosphor powders of the first embodiment are YOX (x = 0.463, y = 0.348), LAP (x = 0.351, y = 0.585). , BAM-B (x = 0.148, y = 0,055).

Furthermore, the phosphor used for emitting each color of red, green, and blue is not limited to one type for each wavelength, and a plurality of types may be used in combination.
Here, the case where a phosphor layer is formed using the above-described phosphor particles for high color reproduction will be described. In this evaluation, there are three evaluations in the case of using a phosphor for high color reproduction based on the area of the NTSC triangle (NTSC triangle) connecting the chromaticity coordinate values of the three primary colors of the NTSC standard in the CIE1931 chromaticity diagram. This is performed by the ratio of the area of the triangle that can connect the chromaticity coordinate values (hereinafter referred to as NTSC ratio).

  For example, when BAM-B is used as blue, BAM-G as green, and YVO as red (Example 1), the NTSC ratio is 92%, and SCA is used as blue, BAM-G as green, and YVO as red. (Example 2) NTSC ratio is 100%, and when SCA is used as blue, BAM-G as green, and YOX as red (Example 3), NTSC ratio is 95 (%). The luminance can be improved by 10 (%) compared to the above.

The chromaticity coordinate values used for the evaluation here are measured in a state where a liquid crystal display device incorporating a lamp or the like is used.
<Summary>
As described above, according to the first embodiment and the first modification of the present invention, a discharge lamp having a stable shape with little irregularity in thickness is realized, and slow leaks and cracks are generated. The rate can be reduced and the yield can be improved.

  The present invention can be widely applied to all discharge lamps, and is particularly effective in a backlight unit. According to the present invention, it is possible to provide a discharge lamp that is not irregular in shape, has little unevenness in thickness, stabilizes the shape, has a low rate of occurrence of slow leaks and cracks, and has a good yield. It can contribute to improvement and reduction of manufacturing cost, and its industrial utility value is extremely high.

It is a figure which shows the outline | summary of the liquid crystal television in Embodiment 1 of this invention. It is a figure which shows the outline | summary of the dielectric barrier discharge lamp 10 in Embodiment 1 of this invention. In the dielectric barrier discharge lamp 10 according to the present embodiment, the sealing portion 7 before forming the external electrodes 3 and 4 in the state in which the discharge medium 2 is sealed and both ends of the cylindrical tube 22 are sealed is centered in the longitudinal direction. It is a figure which shows the cross section cut | disconnected from the pipe | tube parallel to the pipe wall. It is a figure which shows the outline | summary of the first half of the sealing process of the outer envelope. It is a figure which shows the outline | summary of the second half of the sealing process of the outer envelope. It is a figure which shows the outline | summary of the cold cathode fluorescent lamp 50 in the modification 1 of this invention. In the cold cathode fluorescent lamp 50 of this modification, the sealing portion 57 before forming the power supply terminals 53 and 54 in a state where the discharge medium 2 is sealed and both ends of the cylindrical tube 68 are sealed is the tube wall from the center in the longitudinal direction. It is a figure which shows the cross section cut | disconnected in parallel with. In the conventional external electrode type discharge lamp, the sealing portion on the side to be sealed later using the sealing body before forming the external electrode in a state in which the discharge medium is sealed and both ends of the cylindrical tube are sealed in the longitudinal direction It is a figure which shows the cross section cut | disconnected in parallel with the pipe wall from the center.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Outer tube 2 Discharge medium 3 External electrode 4 External electrode 5 Phosphor layer 6 Sealing part 7 Sealing part 10 Dielectric barrier discharge lamp 11 Fusion part 12 Bending part 13 Tube axis 14 Substantially flat part 15 Straight pipe part 16 Inner protrusion 17 Outward protrusion 21 Phosphor layer 22 Cylindrical tube 23 Metal rod 24 Burner 25 Burner 26 Sealing body 27 Insert rod 28 Burner 29 Burner 30 Mercury pellet 31 Burner 32 Burner 33 Cavity 34 Burner 35 Burner 50 Cold cathode Fluorescent lamp 51 Outer tube 53 Power supply terminal 54 Power supply terminal 56 Sealing portion 57 Sealing portion 58 Internal electrode 59 Internal electrode 61 Fusion portion 62 Bending portion 63 Tube shaft 64 Substantially flat portion 65 Straight tube portion 66 Inward protruding portion 67 Outward protrusion 68 Cylindrical tube 69 Sealing body 100 LCD TV 101 LCD screen unit 102 Backlight unit Doo 103 high-frequency electronic ballast

Claims (8)

A discharge lamp in which a discharge medium is sealed in a discharge space in an outer tube formed by sealing both ends of a cylindrical glass tube,
At least one end of the envelope tube is
A cylindrical outer protrusion projecting outward in the tube axis direction opposite to the discharge space with respect to the end of the straight tube portion having substantially the same cross-sectional shape over the entire length, and the straight tube portion A sealing body having a cylindrical inward protruding portion protruding into the discharge space without being in direct contact is connected to the straight tube portion, and the outward protruding portion and the inward protruding portion A discharge lamp characterized in that the outer diameter of the portion is smaller than the inner diameter of the glass tube. The discharge lamp according to claim 1, wherein a thickness of a connecting portion that connects the straight tube portion and the sealing body is substantially equal to a thickness of the straight tube portion. At least one end portion of the outer tube is one in which the glass tube and the sealing body are fused and sealed,
The outward projecting portion and the inward projecting portion are portions where the sealing body is mainly thermally deformed,
The straight tube portion is a portion where the glass tube is not thermally deformed,
The discharge lamp according to claim 1, wherein the connecting portion is a portion where the glass tube is mainly thermally deformed. At least one end portion of the outer tube is one in which the glass tube and the sealing body are fused and sealed,
The inward protrusion is
The discharge lamp according to any one of claims 1 to 3, wherein the sealing body is mainly drawn into the discharge space by a negative pressure. A backlight unit comprising the discharge lamp according to any one of claims 1, 2, 3, and 4 as a light source. A liquid crystal display comprising the discharge lamp according to any one of claims 1, 2, 3, and 4 as a light source of a backlight unit. A discharge lamp manufacturing method in which a discharge medium is sealed in a reduced pressure state in a discharge space in an envelope formed by sealing both ends of a cylindrical glass tube,
In sealing one end of the envelope,
After sealing the other end of the glass tube, temporarily fixing the sealing body to the one end, and making the inside of the glass tube in a reduced pressure state,
The discharge space side of the sealing body is heated together with the glass tube through the glass tube, and the discharge space side of the sealing body is first fused to the glass tube. A method of manufacturing a lamp. After the discharge space side of the insert is first welded to the glass tube, the insert is drawn into the discharge space by a negative pressure, and an inward protruding portion protruding into the discharge space is provided. The discharge lamp manufacturing method according to claim 5, wherein the discharge lamp is formed.

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