JP2008108493A - Low pressure discharge lamp, backlight unit, and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low pressure discharge lamp, a backlight unit, and a liquid crystal display device capable of improving ablation of mercury, an electrode, and a lead wire, and of achieving life-prolongation. <P>SOLUTION: In the low pressure discharge lamp having a glass bulb 101 and the electrode 103 at least at one end part of inner part of the glass bulb 101, the electrode 103 has a bottomed cylindrical form and is joined to the lead wire 104 sealed to the end part of the glass bulb 101 at its bottom face, and the sealing of the glass bulb 101 and the lead wire 104 is carried out by a pinch seal method. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a low-pressure discharge lamp, a backlight unit, and a liquid crystal display device.

  FIG. 18 is a front sectional view including a tube axis of a cold cathode fluorescent lamp which is one of conventional low-pressure discharge lamps. FIG. 19 is a bottom cross-sectional view including the tube axis of a conventional cold cathode fluorescent lamp. FIG. 20 is a cross-sectional view taken along the line AA ′ of FIG. As shown in FIGS. 18 and 19, the cold cathode fluorescent lamp 1 includes a glass bulb 2, an electrode 3, a lead wire 4, and an exhaust thin tube (exhaust tube remainder) 5. The electrode 3 has a V-shape obtained by bending a single plate-like member into two, and is disposed in the glass bulb 2 so that the inner surface thereof faces the end of the glass bulb 2. Are joined to the respective side ends 3a. The two lead wires 4 are sealed by the pinch seal method at the end portion 2 a of the glass bulb 2, and the end opposite to the electrode 3 faces the exhaust thin tube 5 from both ends of the glass bulb 2 in the outward direction. Protruding.

As prior art document information related to the invention of this application, for example, Patent Document 1 is known.
Japanese Patent Publication No. 8-17089

  However, in the case of the conventional cold cathode fluorescent lamp, as shown in FIG. 20, the inner periphery of the cross section (cross section cut perpendicular to the longitudinal direction) of the glass bulb 2 is usually circular, while the electrode 3 When viewed from the longitudinal direction of the glass bulb 2, the shape of the glass bulb 2 becomes a quadrangular shape, so that the gap between the inner surface of the glass bulb 2 and the outer side surface of the electrode 3 inevitably increases. As a result, when the lamp is lit, a discharge enters through the gap and the electrode material is excessively sputtered and the electrode is consumed, and the sputtered substance consumes a large amount of mercury in a short period of time. There is a possibility that the discharge entering from the side attacks the lead wire 4 and the lead wire 4 is consumed, thereby shortening the lamp life. Therefore, a case where a shape along the inner peripheral shape of the glass bulb 2, that is, a cylindrical electrode was applied instead of the electrode 3 was examined. First, as a joining method with the lead wire 4, the lead wire 4 was joined to the outer side surface of the cylindrical electrode. As a result, it is necessary to provide at least a gap corresponding to the wire diameter of the lead wire 4 between the inner surface of the glass bulb 2 and the outer side surface of the electrode. Eventually, discharge enters from the gap during lamp operation. I found that I couldn't prevent it.

  In addition, when the electrode is consumed, for example, a hole is formed in the electrode, and the heat dissipation is reduced, which adversely affects the glass bulb 2. When the lead wire 4 is consumed, for example, the lead wire 4 is broken as it is.

  Therefore, the low-pressure discharge lamp according to the present invention aims to suppress the consumption of mercury, electrodes and lead wires, and to prolong the life.

  In order to solve the above problems, a low-pressure discharge lamp according to the present invention is a low-pressure discharge lamp having a glass bulb and an electrode at least at one end inside the glass bulb, wherein the electrode has a bottomed cylindrical shape, and A lead wire sealed to an end portion of the glass bulb is bonded to the bottom surface of the outside, and the sealing between the glass bulb and the lead wire is performed by a pinch seal method. To do.

  The low-pressure discharge lamp according to the present invention has an exhaust pipe remaining portion at at least one end portion of the glass bulb, and an interval between an end surface located in the glass bulb in the exhaust pipe remaining portion and a bottom surface of the electrode is 0. It is preferable that it is more than 5 [mm].

  In the low-pressure discharge lamp according to the present invention, it is preferable that the lead wire has at least one bent portion and is joined to the electrode linearly or in a planar shape.

  In the low-pressure discharge lamp according to the present invention, the lead wire is bent in a U-shape, and an intermediate portion sandwiched between the two bent portions and a bottom surface on the outer side of the electrode are linear or surface. It is preferable that it is joined in a shape.

  In the low-pressure discharge lamp according to the present invention, it is preferable that a convex portion is provided on the bottom surface of the electrode, and at least a side surface of the convex portion and the lead wire are joined linearly or planarly.

  In the low-pressure discharge lamp according to the present invention, a convex portion is provided on the bottom surface of the electrode, the convex portion has a groove portion, and at least the inner surface of the groove portion and the lead wire are joined linearly or in a planar shape. It is preferable.

  In the low-pressure discharge lamp according to the present invention, it is preferable that the glass bulb has an alkali metal content of 3 [mol%] to 20 [mol%].

  In the low-pressure discharge lamp according to the present invention, the glass bulb preferably has an outer diameter of 4 [mm] or more.

In the low-pressure discharge lamp according to the present invention, the inner diameter (D ₁ ) [mm] of the glass bulb and the outer diameter (D ₂ ) [mm] of the cylindrical electrode are related to D ₁ −0.4 ≦ D. _{2 <which} is preferably regulated so as to satisfy D _1.

  In the low-pressure discharge lamp according to the present invention, the glass bulb preferably has a substantially flat cross section including a plane perpendicular to the tube axis in the light extraction portion.

  The backlight unit according to the present invention includes the low-pressure discharge lamp.

  The liquid crystal display device according to the present invention includes the backlight unit.

  The low-pressure discharge lamp according to the present invention can suppress the consumption of mercury, electrodes and lead wires, and can extend the life.

  Further, the backlight unit according to the present invention can provide a longer-lifetime backlight unit by suppressing the consumption of mercury, the electrodes and the lead wires in the low-pressure discharge lamp therein, and extending the life. .

  In addition, the liquid crystal display device according to the present invention can provide a longer-lifetime liquid crystal display device by suppressing the consumption of mercury, electrodes, and lead wires of the low-pressure discharge lamp therein and extending the life. .

(First embodiment)
A front sectional view including a tube axis of a low-pressure discharge lamp according to a first embodiment of the present invention is shown in FIG. 1, and a bottom sectional view thereof is shown in FIG. A low-pressure discharge lamp 100 (hereinafter simply referred to as “lamp 100”) according to the first embodiment of the present invention includes a cold bulb fluorescent lamp including a glass bulb 101, an exhaust pipe remaining portion 102, an electrode 103, and a lead wire 104. It is.

  The glass bulb 101 is made of, for example, soda glass, has an outer diameter of 6 [mm], an inner diameter of 5 [mm], an overall length of 720 [mm], and a cross-sectional shape (inner circumference) cut perpendicular to the tube axis. The shape of the surface and the inner peripheral surface) is substantially circular. The outer diameter of the glass bulb 101 is preferably 4 [mm] or more. This is because when the outer diameter of the glass bulb 101 is 4 [mm] or more, it is easy to seal the glass bulb 101 and the lead wire 104 by the pinch seal method.

The material of the glass bulb 101 is not limited to soda glass, and lead glass, lead-free glass, borosilicate glass, or the like may be used. When soda glass, lead glass, or lead-free glass is used, the dark startability can be improved. That is, the glass as described above contains a lot of alkali metal oxides typified by sodium oxide (Na ₂ O), and the dark startability can be improved by these alkali metal oxides. For example, when the alkali metal oxide is sodium oxide, the sodium (Na) component elutes on the inner surface of the glass bulb 101 over time. Since sodium has a low electronegativity, it is considered that sodium eluted at the inner end of the glass bulb 101 (where no protective film is formed) contributes to improving the dark startability.

  In particular, in an external electrode fluorescent lamp such as a low-pressure discharge lamp according to a second embodiment of the present invention, which will be described later, and an external electrode fluorescent lamp formed so as to cover the outer peripheral surface of the end portion of the glass bulb 101, the glass bulb The content of the alkali metal oxide in the material 101 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 exceeds 1 [second] is low (in other words, if it is 5 [mol%] or more, the probability that the dark start time is within 1 [second] is high. If it exceeds 20 [mol%], the glass bulb will become black (brown) or white when used for a long time, resulting in a decrease in brightness, or a reduction in the strength of the glass bulb. Because.

  In consideration of protection of the natural environment, it is preferable to use lead-free glass. However, even if lead-free glass is used, lead may be included as an impurity in the manufacturing process, so glass containing lead at a level of 0.1 [wt%] or less is also defined as lead-free glass. I will do it.

By adjusting the thermal expansion coefficient of these glasses, the sealing strength with a sealing member such as a lead wire of a cold cathode fluorescent lamp can be increased. For example, when the sealing member is made of tungsten (W), it is preferably set to 36 × 10 ⁻⁷ [K ⁻¹ ] to 45 × 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 4 [mol%]-10 [mol%].

When the sealing member is made of Kovar or Molybdenum (Mo), the sealing member is preferably set to 45 × 10 ⁻⁷ [K ⁻¹ ] to 56 × 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 7 [mol%]-14 [mol%].

Further, when the sealing member is made of Jumet, 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 with 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 becomes large, 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 that makes sealing difficult, so 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, 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.

  The shape of the glass bulb 101 is not limited to a substantially circular cross section cut perpendicularly to the tube axis, and may be a substantially flat shape. Here, the “substantially flat shape” means an elliptical shape or a rounded shape such as a raceway shape (track shape). For example, the cross section cut perpendicularly to the tube axis in a portion 101a (hereinafter simply referred to as “light extraction portion 101a”) sandwiched between the inner end faces of the electrode 103 in the glass bulb 101 is formed into a substantially flat shape. Therefore, the portion having a substantially flat cross section has an outer peripheral surface area larger than that of a low-pressure discharge lamp having a substantially circular cross section having a tube outer diameter similar to the short outer diameter of the cross section, and the coldest spot temperature is excessive. The rise can be suppressed. In addition, the short inner diameter of the cross section in such a low-pressure discharge lamp is shorter than that of a substantially circular low-pressure discharge lamp having a tube inner diameter comparable to the long inner diameter. The distance can be kept substantially short. For this reason, even if the lamp current is made larger than the conventional one, it is possible to make it difficult to lower the light emission efficiency.

  Further, not only the light extraction portion 101a but also a cross section cut perpendicularly to the tube axis over the entire length of the glass bulb 101 may be a substantially flat shape. In this case, the outer peripheral cross-sectional shape of the electrode 103 is preferably substantially flat so as to follow the inner surface shape of the glass bulb 101. This is to reduce the gap between the inner surface of the glass bulb 101 and the outer surface of the electrode 103 and prevent discharge from entering through the gap.

A phosphor layer 105 is formed on the inner surface of the glass bulb 101. The phosphor layer 105 is made of, for example, a red phosphor (Y ₂ O ₃ : Eu ³⁺ ), a green phosphor (LaPO ₄ : Ce ³⁺ , Tb ³⁺ ), and a blue phosphor (BaMg ₂ Al ₁₆ O ₂₇ : Eu ²⁺ ). Formed of a rare earth phosphor. The configuration of the phosphor layer 105 is not limited to the above configuration. For example, red phosphor (YVO ₄ : Eu ³⁺ ), green phosphor (BaMg ₂ Al ₁₆ O ₂₇ : Eu ²⁺ , Mn ²⁺ ), blue phosphor (BaMg ₂ Al ₁₆ O ₂₇ : Eu ²⁺ ) and the like 313. A phosphor that absorbs [nm] ultraviolet rays may be included. As described above, when a phosphor that absorbs ultraviolet rays of 313 [nm] is included in an amount of 50 [wt%] or more of the total weight of the phosphors, the ultraviolet rays of 313 [nm] almost leak out of the lamp 100. When the lamp 100 is mounted on the backlight unit 300 (see FIG. 6), it is possible to prevent the resin used for the optical sheets 302 (see FIG. 6) from being deteriorated by ultraviolet rays. In particular, when a polycarbonate (PC) resin is used as the diffusion plate 308 (see FIG. 6) of the optical sheet 302, it is affected by deterioration or discoloration due to ultraviolet rays of 313 [nm], compared with the case where an acrylic resin is used. It is easy to receive. Therefore, when the phosphor layer 105 includes a phosphor that absorbs ultraviolet rays of 313 [nm], the characteristics as the backlight unit are maintained for a long time even in the case of the backlight unit using the PC resin diffusion plate 308. be able to.

  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. The intensity of the excitation wavelength spectrum at 313 [nm] is defined as 80 [%] or more. 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.

Further, a protective film (not shown) of a metal oxide such as yttrium oxide (Y ₂ O ₃ ) may be provided between the inner surface of the glass bulb 101 and the phosphor layer 105.

  Further, inside the glass bulb 101, for example, about 4 [mg] mercury and a neon / argon mixed gas (Ne95 [%] + Ar5) of about 2.7 [kPa] (20 [° C.]) as a rare gas. [%]) Is enclosed.

  In addition, the structure of mercury and a noble gas is not limited to the said structure. The rare gas contains at least one kind of helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), etc., and two or three kinds may be mixed and used. For example, argon (Ar100 [%]) may be used, or neon-krypton mixed gas (Ne95 [%] + Kr5 [%]) may be used. When a neon / krypton mixed gas is used as the rare gas, the startability of the lamp 100 is improved, and the lamp 100 can be lit at a low voltage.

  An exhaust pipe and a lead wire 104 are attached to the end of the glass bulb 101 in the manufacturing process of the lamp 100. This exhaust pipe is used when exhausting the inside of the glass bulb 101 or sealing a rare gas or the like after sealing the lead wire 104, and the enclosure of the rare gas or the like inside the glass bulb 101 is completed. Then, at the portion located outside the glass bulb 101 in the exhaust pipe, for example, chip-off sealing is performed and the exhaust pipe remaining portion 102 is formed. In the exhaust pipe remaining portion 102, the end opposite to the tip-off portion 102 a is located in the glass bulb 101.

  FIGS. 1 and 2 show a completed lamp when the exhaust pipe is attached to both ends of the glass bulb 101 in the manufacturing process of the lamp 100. As in the completed lamp shown in FIG. You may attach only to the end of 101. FIG. When the exhaust pipe is attached to only one end of the glass bulb 101, the first sealing side and the second sealing side of the lamp 100 after completion can be easily distinguished, and the backlight unit 300 (FIG. 6). By alternately incorporating the first sealing side and the second sealing side into the reference), the luminance of the backlight unit 300 as a whole can be made uniform.

  Since the lamp 100 has a smaller diameter than a fluorescent lamp for general illumination, it becomes difficult to form a phosphor layer 105 having a uniform film thickness on the inner surface of the glass bulb 101 as the length of the lamp 100 increases. In general, the thickness of the phosphor layer 105 is not uniform in the longitudinal direction of the glass bulb 101, and increases, for example, from the first sealing portion side to the second sealing portion side. When a plurality of such lamps 100 are arranged in the backlight unit 300 and incorporated in an arbitrary direction, the backlight unit 300 as a whole may have uneven brightness. In order to prevent this, it is necessary to alternately reverse the direction of the lamp axis direction of the lamp 100 incorporated in the backlight unit 300 one by one. Alternatively, even when one lamp 100 is used, it is necessary to correct the optical system in accordance with the direction of the lamp 100. Therefore, by determining the first sealing side and the second sealing side of the lamp 100 based on the presence or absence of the exhaust pipe remaining portion 102, it is possible to easily correct the luminance unevenness of the backlight unit as a whole when incorporated in the backlight unit. It can be carried out. Even when the exhaust pipe remaining portions 102 are at both ends of the glass bulb 101, the first sealing side and the second sealing side are distinguished by changing the shape, size, and mounting position of each exhaust pipe remaining portion 102. Is possible.

  On the contrary, by making the shape, size and mounting position of each exhaust pipe remaining portion 102 the same, the shape of both ends of the lamp 100 becomes substantially the same, and when incorporating them into the backlight unit, Since insertion is possible regardless of the direction of the tube axis direction of 100, the insertion process of the lamp 100 can be facilitated. This is particularly effective when the thickness of the phosphor layer 105 can be formed uniformly in the longitudinal direction of the lamp 100.

  The electrode 103 has a bottomed cylindrical shape made of, for example, nickel (Ni), has an overall length s of 12.5 [mm], and an outer diameter of 4.7 [mm] (an inner diameter of 4.2 [mm]).

Here, when the inner diameter of the glass bulb 101 is D ₁ [mm] and the outer diameter of the electrode 103 is D ₂ [mm], it is preferable that the relational expression D ₁ −0.4 ≦ D ₂ <D ₁ is satisfied. . As a result, even when the lamp current during lamp lighting is a large current of 5 [mA] or more, the discharge during lighting is less likely to fly to the outer side surface of the electrode 103, suppressing excessive sputtering of the electrode material, or In addition to suppressing the mercury consumption rate associated therewith, the discharge that reaches the lead wire 104 through the outer side surface of the electrode 103 is prevented from attacking the lead wire 104 and consuming the lead wire 104, thereby reducing the pressure. The life of the discharge lamp 100 can be extended.

  Further, when the distance between the inner surface of the glass bulb 101 and the outer side surface of the electrode 103 is d [mm], it is preferable that the relational expression of 0 <d ≦ 0.2 is satisfied. Even in this case, the discharge during lighting is less likely to fly to the outer side surface of the electrode 103, and excessive sputtering of the electrode material can be suppressed, and the accompanying mercury consumption rate can be suppressed. The life of the low-pressure discharge lamp 100 can be extended by suppressing the discharge that passes through the side surface and reaches the lead wire 104 from attacking the lead wire 104 and consuming the lead wire 104. Further, in this case, since the gap between the outer surface of the electrode 103 and the inner surface of the glass bulb 101 is not biased, discharge concentrates on a wide portion of the gap and the surface temperature of the glass bulb 101 at that portion rises. It is possible to prevent deformation of the optical sheets of the backlight unit that is vulnerable to heat.

  Note that the material of the electrode 103 is not limited to nickel (Ni). For example, in consideration of suppression of mercury consumption due to sputtering of the electrode material, niobium (Nb), tantalum (Ta), or molybdenum (less spatter) is considered. It is preferable to apply Mo).

In addition, it is preferable that the space | interval of the end surface located in the glass bulb | bulb 100 among the edge parts of the exhaust pipe remainder 102 and the outer bottom face of the electrode 103 is 0.5 [mm] or more. When the interval is narrower than 0.5 [mm], it is difficult to supply and exhaust air from the exhaust pipe in the manufacturing process of the lamp 100. Furthermore, when performing pinch molding of the glass bulb 101 while flowing an antioxidant gas such as nitrogen (N ₂ ) or the like, if the end face of the exhaust pipe and the bottom surface outside the electrode 103 are close, the antioxidant gas from the exhaust pipe In addition, the antioxidant gas is ejected from the narrow gap, and an unnecessary bulge occurs at the end of the glass bulb 101, and the shape of the end of the glass bulb 101 becomes unstable. Variation will occur.

  The lead wires 104 are paired in pairs, and are made of, for example, an alloy of Fe, Ni, and Cr, and have a wire diameter of 0.3 [mm] and a total length of 50 [mm]. One end face of each of the two lead wires 104 forming a set is juxtaposed to the bottom face outside the electrode 103, for example, by laser welding. In this case, the lead wire 104 is joined to the electrode 103 in a substantially dot shape. The lead wire 104 is joined to the outer bottom surface of the electrode 103, so that the inner surface of the glass bulb 101 and the outer side surface of the electrode 103 are compared to the case where the lead wire 104 is joined to the outer side surface of the electrode 103. The gap between the electrode and the electrode can be made smaller, and the discharge can be prevented from entering the gap, so that the electrode material can be prevented from being excessively sputtered and mercury can be consumed in a large amount in a short period of time. In addition, it is possible to extend the life of the lamp by preventing the discharge that reaches the lead wire 104 from passing through the outer side surface of the electrode 103 from attacking the lead wire 104 and depleting the lead wire 104. can do.

  Note that the lead wire 104 is not limited to the above material, and an alloy of Fe and Ni, for example, can be used. Further, the lead wire 104 is not limited to a case of being made of only one kind of metal, and may be, for example, a joint line in which different materials are welded, such as an alloy wire of Fe and Ni and a dumet wire.

  As shown in FIG. 4, a hole is provided in advance at a position where the lead wire 104 is to be joined to the bottom surface on the outer side of the electrode 103, and after inserting the lead wire 104 into the hole, the electrode 103 and the lead wire 104 are connected. By joining by laser welding or the like, the stability of joining of the electrode 103 and the lead wire 104 can be enhanced.

  As described above, according to the configuration of the low-pressure discharge lamp 100 according to the first embodiment of the present invention, it is possible to extend the life.

(Second Embodiment)
FIG. 5 shows a cross-sectional view including the line axes of the two lead wires of the low-pressure discharge lamp according to the second embodiment of the present invention. As shown in FIG. 5, a low-pressure discharge lamp 200 (hereinafter simply referred to as “lamp 200”) according to the second embodiment of the present invention has an external electrode 201 on one outer surface and one inside the other end. This is an internal / external electrode fluorescent lamp having an internal electrode 103.

  The lamp 200 has an external electrode 201 on the outer surface of one end thereof, and has substantially the same configuration as that of the low-pressure discharge lamp 100 according to the first embodiment of the present invention except for the configuration associated therewith. Therefore, the external electrode 201 and the configuration accompanying it will be described in detail, and the other points will be omitted.

  The external electrode 201 is made of, for example, an aluminum metal foil, and is attached so as to cover the entire outer peripheral surface of the end portion of the glass bulb 101 with a conductive adhesive (not shown) in which metal powder is mixed with silicone resin. ing. In addition, in a conductive adhesive, you may use a fluororesin, a polyimide resin, or an epoxy resin instead of a silicone resin.

  In addition, the external electrode 201 may be formed by applying a silver paste to the entire circumference of the electrode forming portion of the glass bulb 101 instead of sticking the metal foil to the glass bulb 101 with a conductive adhesive, A metal cap may be put on the end of the glass bulb 101.

Although not shown in FIG. 5, a protective film of, for example, yttrium oxide (Y ₂ O ₃ ) may be provided on the inner surface of the glass bulb 101 and in the region where the external electrode 201 is formed. By providing the protective film, it is possible to prevent glass scraping and pinholes caused by mercury ions bombarding the portion of the glass bulb 101.

The protective film may be made of metal oxide such as silica (SiO ₂ ) or alumina (Al ₂ O ₃ ) instead of yttrium oxide. In particular, when the protective film is formed of yttrium oxide or silica, mercury hardly adheres to the protective film, and mercury consumption is low.

  However, the protective film is not an essential component in the present invention and may not be formed at all, or may be formed over the entire inner surface of the glass bulb 101.

  In the example shown in FIG. 5, the exhaust pipe remaining portion 102 is only on the internal electrode 103 side, but it may be only on the external electrode 201 side or on both sides thereof.

  As described above, the low-pressure discharge lamp 200 according to the second embodiment of the present invention has the above-described configuration, like the low-pressure discharge lamp 100 according to the first embodiment of the present invention, mercury, the electrode 103, and the lead wire 104. It is possible to suppress the wear of the battery and extend its life.

(Third embodiment)
An exploded perspective view of the backlight unit according to the third embodiment of the present invention is shown in FIG. As shown in FIG. 6, the backlight unit 300 is a direct type, and only the lamp 100 and the surface on the liquid crystal panel side from which light is extracted are opened, and a housing 301 that houses a plurality of fluorescent lamps 100, and a housing And an optical sheet 302 covering the opening of the body 301. The backlight unit 300 is disposed on the back surface of a liquid crystal panel (not shown), and is used as a light source device in the liquid crystal display device 500 (see FIG. 8).

The housing 301 is made of, for example, polyethylene terephthalate (PET) resin, and a reflective surface 303 is formed on the inner surface thereof by vapor deposition of a metal such as silver. In addition, as a material of the housing | casing 301, you may comprise by metal materials, such as materials other than resin, for example, aluminum, a cold rolled material (for example, SPCC). In addition to the metal vapor-deposited film, the reflective surface 303 of the inner surface is affixed to the housing 301 with a reflective sheet having a higher reflectance by adding calcium carbonate, titanium dioxide (TiO ₂ ), etc. to polyethylene terephthalate (PET) resin, for example. You may comprise.

  In addition, the lamp 100, the connection terminal 304, and the cover 311 are disposed inside the housing 301.

  The connection terminals 304 are paired with two terminals that are spaced apart in the longitudinal direction of the housing 301, and the pairs are disposed at a predetermined interval in the short direction of the housing 301. The lamp 100 is incorporated between two terminals that make a pair. The cover 311 is for ensuring insulation of terminals arranged in the short direction of the housing 301.

  FIG. 6B is an enlarged cross-sectional view of a main part showing a state of joining between the lead wire 104 of the lamp 100 and the connection terminal 304. As shown in FIG. 6B, each connection terminal 304 includes a power supply line 305 and a cap 306.

  The power supply line 305 is for electrically connecting the lamp 100 to a lighting circuit (not shown), and is connected to the lead wire 104 of the lamp 100 by, for example, solder 307 or the like.

  The cap 306 is made of, for example, an insulating material such as rubber, and is used to insulate a connection portion between the lead wire 104 and the power supply wire 305 from the outside. Are provided so as to cover the connecting portion of the power supply line 305.

  As shown in FIG. 6A, the lamp 100 is the low-pressure discharge lamp 100 (cold cathode fluorescent lamp) according to the first embodiment of the present invention. The low-pressure discharge lamp 200 (internal / external electrode fluorescent lamp) according to the embodiment can also be applied.

  The optical sheet 302 includes a diffusion plate 308, a diffusion sheet 309, and a lens sheet 310, for example, as shown in FIG. The diffusion plate 308 is a plate-like body made of, for example, polymethyl methacrylate (PMMA) resin, and is disposed so as to close the opening of the housing 301. The diffusion sheet 309 is made of, for example, a polyester resin. The lens sheet 310 is, for example, a laminate of an acrylic resin and a polyester resin. These optical sheets 302 are arranged so as to be sequentially superimposed on the diffusion plate 308.

  With the above-described configuration, the backlight unit 300 according to the third embodiment of the present invention suppresses the consumption of mercury in the lamp 100, the electrode 103, and the lead wire 104, thereby extending the life of the backlight unit 300. A light unit can be provided.

(Fourth embodiment)
FIG. 7 shows a partially cutaway perspective view of a backlight unit according to the fourth embodiment of the present invention. As shown in FIG. 7, the backlight unit 400 is an edge light system, and includes a reflection plate 401, a lamp 100, a connection terminal (not shown), a light guide plate 402, a diffusion sheet 403, and a prism sheet 404.

  The reflection plate 401 is disposed so as to surround the periphery of the light guide plate 402 except for the liquid crystal panel side (arrow Q), and the side surface covering the bottom surface portion 401a covering the bottom surface and the side surface excluding the side where the lamp 100 is disposed. Part 401b and a curved lamp side surface part 401c covering the periphery of the lamp 100, and reflects light emitted from the lamp from the light guide plate 402 to the liquid crystal panel (not shown) side (arrow Q). . Further, the reflection plate 401 is made of, for example, a film-like PET deposited with silver or laminated with a metal foil such as aluminum.

  The connection terminal has substantially the same configuration as the connection terminal 304 used in the backlight unit 300 according to the third embodiment. In FIG. 7, the end of the lamp 100 is omitted for convenience of illustration.

  The light guide plate 402 is for guiding the light reflected by the reflection plate to the liquid crystal panel side. The light guide plate 402 is made of, for example, translucent plastic, and is stacked on the reflection plate 401 provided on the bottom surface of the backlight unit 400. It is weighted. As a material, polycarbonate (PC) resin or cycloolefin-based resin (COP) can be applied.

  The diffusion sheet 403 is for expanding the visual field, and is made of a film having a diffusion transmission function made of, for example, polyethylene terephthalate resin or polyester resin, and is stacked on the light guide plate 402.

  The prism sheet 404 is for improving luminance, and is made of, for example, a sheet obtained by bonding an acrylic resin and a polyester resin, and is stacked on the diffusion sheet 403. A diffusion plate may be further stacked on the prism sheet 404.

  In the case of the present embodiment, an aperture type lamp in which a reflection sheet is provided on the outer surface of the glass bulb 101 except for a part in the circumferential direction of the lamp 100 (on the light guide plate 402 side when inserted into the backlight unit 400). It may be. Moreover, it can replace with the lamp | ramp 100 and the low pressure discharge lamp 200 which concerns on the 2nd Embodiment of this invention is applicable.

  With the above configuration, the backlight unit 400 according to the fourth embodiment of the present invention suppresses the consumption of mercury in the lamp 100, the electrode 103, and the lead wire 104, thereby extending the life of the backlight unit 400. A light unit can be provided.

(Fifth embodiment)
An outline of a liquid crystal display device according to a fifth embodiment of the present invention is shown in FIG. As shown in FIG. 8, the liquid crystal display device 500 is, for example, a 32-inch liquid crystal television as shown in FIG. 8, a liquid crystal screen unit 501 including a liquid crystal panel and the like, and a backlight unit according to the third embodiment of the present invention. 300 and a lighting circuit 502.

  The liquid crystal screen unit 501 is a publicly known one and includes a liquid crystal panel (color filter substrate, liquid crystal, TFT substrate, etc.) (not shown), a drive module, etc. (not shown), and is based on an image signal from the outside. To form a color image.

  The lighting circuit 502 lights the lamp 100 inside the backlight unit 300. The lamp 100 is operated at a lighting frequency of 40 [kHz] to 100 [kHz] and a lamp current of 3.0 [mA] to 20 [mA].

  In FIG. 8, the case where the low-pressure discharge lamp 100 according to the first embodiment is inserted into the backlight unit 300 according to the third embodiment of the present invention as the light source device of the liquid crystal display device 500 has been described. The low-pressure discharge lamp according to the second embodiment of the present invention is not limited thereto.

  With the above-described configuration, the liquid crystal display device 500 according to the fifth embodiment of the present invention suppresses the consumption of mercury in the lamp 100, the electrode 103, and the lead wire 104, thereby extending the life, thereby providing a liquid crystal with a longer life. A display device can be provided.

<Modification>
As described above, the present invention has been described based on the specific examples shown in the above embodiments. However, the content of the present invention is not limited to the specific examples shown in the respective embodiments. Variations can be used.

1. Modification 1
The modified example 1 of the low-pressure discharge lamp according to the first embodiment of the present invention differs from the low-pressure discharge lamp according to the first embodiment of the present invention in the shape of the lead wire and the bonding state between the lead wire and the electrode. . Specifically, the lead wire is bent in an L shape, and is different in that it is joined to almost the entire bent portion and the bottom surface outside the electrode. That is, the lead wire is joined to the electrode substantially linearly or in a planar shape.

  FIG. 9A is an enlarged front cross-sectional view including a tube axis of Modification 1 of the low-pressure discharge lamp according to the first embodiment of the present invention, and FIG. Each is shown. In the first modification, the end portion of one lead wire 106 extending in the tube axis direction of the lamp 107 is bent in an L shape in a direction parallel to the bottom surface on the outer side of the electrode 103, and the bent portion 106 a is almost the same. The whole and the outer bottom surface of the electrode 103 are joined. With this configuration, the contact area between the lead wire 106 and the outer bottom surface of the electrode 103 can be increased, and the stability of bonding between the lead wire 106 and the electrode 103 can be improved.

2. Modification 2
Modified example 2 of the low-pressure discharge lamp according to the first embodiment of the present invention differs from modified example 1 in the shape of the lead wire and the sealing state with the glass bulb. The lead wire is bent in a U-shape, and the lead wire is different in that both portions except for the intermediate portion sandwiched between the bent portions are sealed to the glass bulb.

  FIG. 10A is an enlarged front cross-sectional view including the tube axis of the modified example 2 of the low-pressure discharge lamp according to the first embodiment of the present invention, and FIG. Each is shown. In this case, one lead wire 108 is bent in a U-shape, and substantially the entire intermediate portion 108 a sandwiched between the two bent portions and the bottom surface outside the electrode 103 are joined. That is, the lead wire 108 is joined to the electrode 103 in a substantially linear or planar manner at the intermediate portion 108a. With this configuration, the contact area between the lead wire 108 and the outer bottom surface of the electrode 103 can be increased, and the stability of bonding between the lead wire 108 and the electrode 103 can be improved. In addition, the lead wire 108 is supported by being sealed to the glass bulb 101 at both portions except for the intermediate portion 108a. Therefore, the axial displacement of the electrode 103 supported by the glass bulb 101, that is, the inclination of the central axis in the longitudinal direction of the electrode 103 with respect to the tube axis of the glass bulb 101 can be suppressed.

3. Modification 3
Modified example 3 of the low-pressure discharge lamp according to the first embodiment of the present invention differs from modified example 2 in the shape of the lead wire. Specifically, the intermediate portion sandwiched between the two bent portions of the lead wire bent in the U-shape of the lead wire is bent in a zigzag shape while being parallel to the bottom surface of the outer side of the electrode. Different.

  FIG. 11A is an enlarged cross-sectional view of the main part including the tube axis of the modified example 3 of the low-pressure discharge lamp according to the first embodiment of the present invention, and FIG. Show. In this case, one lead wire 110 is first bent into a U-shape, and the intermediate portion 110 a sandwiched between the two bent portions is zigzag while keeping parallel to the bottom surface outside the electrode 103. It is bent twice to form a shape. That is, the intermediate part 110a is bent in a substantially Z shape. With this configuration, the contact area between the lead wire 110 and the bottom surface of the electrode 103 is further increased, the stability of the joining between the lead wire 110 and the bottom surface of the electrode 103 is further enhanced, and the electrode 103 with respect to the tube axis of the glass bulb 101 is further enhanced. The inclination of the central axis in the longitudinal direction can be suppressed. Note that the lead wire 110 shown in FIGS. 11A and 11B is obtained by bending the portion 110a sandwiched between the bent portions twice while keeping parallel to the bottom surface outside the electrode. The shape after bending is not limited to this. For example, the intermediate portion 110a may draw a circular orbit parallel to the bottom surface outside the electrode 103, or may be a star shape or a spiral shape.

4). Modification 4
The modification 4 of the low-pressure discharge lamp according to the first embodiment of the present invention differs from the low-pressure discharge lamp according to the first embodiment of the present invention in the shape of the electrodes and the bonding state between the electrodes and the lead wires. Specifically, the electrode has a convex portion protruding from the bottom surface on the outer side, and the lead wire is different in that it is joined in a substantially linear or planar manner on the side surface of the convex portion.

  The principal part expanded sectional view containing the tube axis of the modification 4 of the low voltage | pressure discharge lamp concerning the 1st Embodiment of this invention is shown to Fig.12 (a), and the EE 'sectional drawing is shown in FIG.12 (b), respectively. Show. The modified example 4 has a columnar convex portion 103a protruding from the bottom surface outside the electrode 103, and two lead wires 104 are joined to the side surface of the convex portion 103a. In this case, the contact area between the lead wire 104 and the outer bottom surface of the electrode 103 can be increased, and the stability of bonding between the lead wire 104 and the electrode 103 can be improved. In FIG. 12, the lead wire 104 seems to be bonded not only to the side surface of the convex portion but also to the bottom surface of the electrode, but one end surface of the lead wire 104 located inside the glass bulb 101 is the bottom surface of the electrode. And may be joined. In this case, it is possible to further improve the stability of bonding between the lead wire 104 and the electrode 103 as compared with a case where only the side surface of the convex portion is bonded. Further, a groove having a width approximately equal to the wire diameter of the lead wire 104 is formed on the side surface of the convex portion 103a, and the lead wire 104 is fitted into the groove to be joined, thereby joining the lead wire 104 and the electrode 103. Misalignment can be prevented.

5. Modification 5
The modified example 5 of the low-pressure discharge lamp according to the first embodiment of the present invention differs from the modified example 4 in the shape of the lead wire and the bonding state between the electrode and the lead wire. Specifically, the difference is that the lead wire is wound around the side surface of the convex portion of the electrode.

  FIG. 13A is an enlarged front cross-sectional view including the tube axis of the modified example 5 of the low-pressure discharge lamp according to the first embodiment of the present invention, and FIG. 13B is its FF ′ cross-sectional view. Each is shown. Modification 5 has a columnar convex portion 103a protruding from the outer bottom surface of the electrode 103, and the electrode 103 and the lead wire 113 are substantially lined so that the lead wire 113 is wound around the side surface of the convex portion 103a. Are joined in the shape of a sheet or a sheet. In this case, the stability of joining of the lead wire 113 and the electrode 103 can be further enhanced, and the inclination of the central axis in the longitudinal direction of the electrode 103 with respect to the tube axis of the glass bulb 101 can be suppressed. Note that the number of windings of the lead wire 113 around the convex portion 103a, the direction, and the like are not limited to those shown in FIGS. 13 (a) and 13 (b).

6). Modification 6
The sixth modification of the low-pressure discharge lamp according to the first embodiment of the present invention differs from the second modification in the shape of the electrode and the bonding state of the electrode and the lead wire. Specifically, a convex portion having a groove portion is formed on the bottom surface on the outer side of the electrode, and a lead wire is inserted into the groove portion and joined substantially linearly or in a planar shape. The point is different.

  FIG. 14A is an enlarged front cross-sectional view including a tube axis of a modified example 6 of the low-pressure discharge lamp according to the first embodiment of the present invention, and FIG. 14B is a GG ′ cross-sectional view thereof. Each is shown. Modification 6 has a rectangular parallelepiped shape that protrudes from the bottom surface on the outside of the electrode 103, and has a convex portion in which a groove 103b is formed on the tip surface. This is substantially the same as the second modification, and an intermediate portion 108a thereof is inserted into the groove portion 103b, and the electrode 103 and the lead wire 108 are joined by welding or the like, for example. The width of the groove of the groove portion 103b is approximately the same as the wire diameter of the lead wire, for example, 0.4 [mm].

  In addition, after inserting the intermediate part 108a of the lead wire 108 in the groove part 103b, the lead wire 108 and the electrode 103 can be simply joined by caulking the convex part from the outside. Furthermore, the bonding strength between the lead wire 108 and the electrode 103 can be further increased by welding after caulking.

  In addition to the rectangular parallelepiped shape, the convex portion 103a may have a cylindrical shape, a conical shape, a tetrahedral shape, a hexahedral shape, or the like. In particular, in the case of a rectangular parallelepiped or a cube, when a parallel groove is provided on the side surface and caulking is performed after the lead wire 108 is inserted, the caulking jig is not easily displaced and is easily stabilized.

7). Modification 7
The modified example 7 of the low-pressure discharge lamp according to the first embodiment of the present invention differs from the modified example 6 in the position of the groove of the convex portion of the electrode. Specifically, the difference is that the groove is provided on the side surface instead of the front end surface of the convex portion.

  FIG. 15 (a) shows an enlarged front sectional view of the main part including the tube shaft of the modified example 7 of the low-pressure discharge lamp according to the first embodiment of the present invention, and FIG. 15 (b) shows an enlarged bottom sectional view of the main part. FIG. 15C is a sectional view taken along the line H-H ′. In Modification 6, instead of the groove 103b formed on the tip surface of the protrusion 103a in Modification 5, a groove 103c is formed on the side surface of the protrusion 103a. The lead wire 108 is substantially the same as that of the modification 2. The intermediate portion 108a is inserted into the groove portion 103c, and the electrode 103 and the lead wire 108 are joined by welding or the like, for example.

  In this case, the bonding strength between the electrode 103 and the lead wire 108 in the tube axis direction of the glass bulb 101 can be increased.

8). Modification 8
The modified example 8 of the low-pressure discharge lamp according to the first embodiment of the present invention differs from the modified example 6 in the shape of the groove of the convex portion of the electrode. Specifically, the difference is that the inner side surfaces of the groove portions facing each other are uneven.

  FIG. 16 (a) shows an enlarged front sectional view of the main part including the tube axis of the modified example 8 of the low-pressure discharge lamp according to the first embodiment of the present invention, and FIG. 16 (b) shows an enlarged bottom sectional view of the main part. FIG. 16C is a sectional view taken along line II ′.

  The modified example 8 has substantially the same protrusion 103a as the modified example 6. Furthermore, the groove part 103d is formed in the front end surface of the convex part 103a like the modification 5, However, The inner side surface shape which the groove part 103d mutually opposes is uneven | corrugated shape.

  The lead wire 108 is substantially the same as that of the second modification, and an intermediate portion 108a thereof is inserted into the groove portion 103d, and is sandwiched in a clip shape on the inner side surface of the uneven groove portion 103d.

  In this case, the bonding strength between the electrode 103 and the lead wire 108 can be further increased.

9. Modification 9
The modified example 9 of the low-pressure discharge lamp according to the first embodiment of the present invention differs from the modified example 7 in the shape of the groove of the convex portion of the electrode. Specifically, the difference is that the inner side surfaces of the groove portions facing each other are uneven.

  FIG. 17 (a) shows an enlarged front sectional view of the main part including the tube shaft of the modified example 9 of the low-pressure discharge lamp according to the first embodiment of the present invention, and FIG. 17 (b) shows an enlarged bottom sectional view of the main part. FIG. 17C is a sectional view taken along line JJ ′.

  The modified example 8 has substantially the same convex portion 103a as the modified example 7. Furthermore, the groove part 103d is formed in the side surface of the convex part 103a similarly to the modification 5, but the inner side surface shape which the groove part 103d mutually opposes is uneven | corrugated shape.

  The lead wire 108 is substantially the same as that of the second modification, and an intermediate portion 108a thereof is inserted into the groove portion 103d and sandwiched in a clip shape on the inner side surface of the uneven groove portion 103e.

  In this case, the bonding strength between the electrode 103 and the lead wire 108 in the tube axis direction of the glass bulb 101 can be further increased.

  The present invention can be widely applied to low-pressure discharge lamps, backlight units, and liquid crystal display devices.

Front sectional view including the tube axis of the low-pressure discharge lamp according to the first embodiment of the present invention Similarly bottom view of low-pressure discharge lamp Similarly, in the low-pressure discharge lamp, a front sectional view including the tube axis of the lamp when the exhaust pipe remainder is only on one side (A) The principal part expansion front sectional view of the modification of a low-pressure discharge lamp similarly, (b) AA 'sectional drawing of Fig.4 (a) Front sectional view including a tube axis of a low-pressure discharge lamp according to a second embodiment of the present invention (A) Exploded perspective view of a backlight unit according to a third embodiment of the present invention, (b) Similarly, an enlarged cross-sectional view of a main part showing a connection state between a lamp and a connecting member in the backlight unit The partially cutaway perspective view of the backlight unit according to the fourth embodiment of the present invention. Schematic of a liquid crystal display device according to a fifth embodiment of the present invention (A) Main part expansion front sectional view of the modification 1 of the low pressure discharge lamp concerning the 1st Embodiment of the present invention, (b) Similarly BB 'sectional view (A) Main part enlarged front sectional view of Modification 2 of the low-pressure discharge lamp according to the first embodiment of the present invention, (b) Similarly CC 'sectional view (A) The principal part expansion front sectional view of the modification 3 of the low pressure discharge lamp concerning the 1st Embodiment of the present invention, (b) Similarly DD 'sectional drawing (A) Main part enlarged front sectional view of Modification 4 of the low-pressure discharge lamp according to the first embodiment of the present invention, (b) Similarly EE 'sectional view (A) The principal part expanded sectional view of the modification 5 of the low voltage | pressure discharge lamp which concerns on the 1st Embodiment of this invention, (b) Similarly FF 'sectional drawing (A) Main part enlarged front sectional view of Modification 6 of the low-pressure discharge lamp according to the first embodiment of the present invention, (b) Similarly GG 'sectional view (A) Main part enlarged front sectional view of Modification 7 of the low pressure discharge lamp according to the first embodiment of the present invention, (b) Main part enlarged bottom sectional view of Modification 7 of the low pressure discharge lamp, (c) Similarly HH 'cross section (A) Main part enlarged front sectional view of Modification 8 of the low pressure discharge lamp according to the first embodiment of the present invention, (b) Main part enlarged bottom sectional view of Modification 8 of the low pressure discharge lamp, (c) Similarly II 'sectional view (A) Main part enlarged front sectional view of Modification 9 of the low pressure discharge lamp according to the first embodiment of the present invention, (b) Main part enlarged bottom sectional view of Modification 9 of the low pressure discharge lamp, (c) JJ 'sectional view Front sectional view including the tube axis of a conventional cold cathode fluorescent lamp Similarly, a bottom cross-sectional view including the tube axis of the cold cathode fluorescent lamp AA 'sectional view of FIG.

Explanation of symbols

2,101 Glass bulb 3,103 Electrode 4,104,106,108,110,113 Lead wire 100,107,109,111,112,114,115,116,117,118,200 Low pressure discharge lamp 102 Exhaust pipe remainder 103a Convex part 300,400 Backlight unit 500 Liquid crystal display device

Claims (12)

In a low-pressure discharge lamp having an electrode at at least one end inside a glass bulb and the glass bulb, the electrode has a bottomed cylindrical shape, and is sealed to the end of the glass bulb at the bottom of the outside. A lead wire is joined, and the glass bulb and the lead wire are sealed by a pinch seal method. There is an exhaust pipe remaining portion at at least one end of the glass bulb, and an interval between an end surface located in the glass bulb in the exhaust pipe remaining portion and a bottom surface of the electrode is 0.5 [mm] or more. The low-pressure discharge lamp according to claim 1. 3. The low-pressure discharge lamp according to claim 1, wherein the lead wire has at least one bent portion and is joined to the electrode in a linear or planar shape. The lead wire is bent in a U-shape, and an intermediate portion sandwiched between the two bent portions and an outer bottom surface of the electrode are joined in a linear shape or a planar shape. The low-pressure discharge lamp according to claim 1 or 2. The convex part is provided in the bottom face of the said electrode, The side surface of the said convex part and the said lead wire are joined linearly or planarly, The any one of Claims 1-4 characterized by the above-mentioned. Low pressure discharge lamp. A convex portion is provided on the bottom surface of the electrode, the convex portion has a groove portion, and at least the inner surface of the groove portion and the lead wire are joined in a linear or planar shape. The low-pressure discharge lamp according to any one of 5. The low pressure discharge lamp according to any one of claims 1 to 6, wherein the glass bulb has an alkali metal content of 3 [mol%] to 20 [mol%]. The low-pressure discharge lamp according to any one of claims 1 to 7, wherein an outer diameter of the glass bulb is 4 [mm] or more. The inner diameter (D ₁ ) [mm] of the glass bulb and the outer diameter (D ₂ ) [mm] of the electrode are regulated so as to satisfy the relational expression D ₁ −0.4 ≦ D ₂ <D ₁ . The low-pressure discharge lamp according to any one of claims 1 to 8. The low-pressure discharge lamp according to any one of claims 1 to 9, wherein the glass bulb has a substantially flat cross section cut perpendicular to the tube axis. A backlight unit comprising the low-pressure discharge lamp according to claim 1. A liquid crystal display device comprising the backlight unit according to claim 11.

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