JP2006351460A - Cold cathode fluorescent lamp and backlight unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cold cathode fluorescent lamp easy to mount, having a long life and sufficient brightness. <P>SOLUTION: The cold cathode fluorescent lamp is provided with a glass bulb 10, a pair of hollow electrodes 20 sealed at both end parts of the glass bulb 10, and power supply terminals 30 arranged at outside of both end parts of the glass bulb 10, connected to lead wires 22 of the hollow electrodes 20. Banking parts 27, larger than outer diameter of the lead wire 22 at a side connected to the glass bulb 10, are formed on the lead wire 22 at the part connected to the power supply terminals 30. Further, the banking parts 27 are closely contacted to both end parts of the glass bulb 10, Part of the power supply terminal 30 excluding the part contacting the lead wire 22 is a thin film formed on the external surface of the glass bulb 10. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a cold cathode fluorescent lamp and a backlight unit using the cold cathode fluorescent lamp as a light source.

  Conventionally, there is a cold cathode fluorescent lamp 200 in which a cap-shaped power supply terminal 202 is provided at an end of a glass bulb 201 as shown in FIG. 11 (Patent Document 1). Since the power supply terminal 202 is electrically connected to the lead wire 204 of the electrode 203, if the end of the cold cathode fluorescent lamp 200 is fitted into a socket (not shown) of a lighting device such as a backlight unit, the cold cathode fluorescent lamp is used. The lamp 200 can be fixed to the lighting device, and the cold cathode fluorescent lamp 200 and the lighting circuit of the lighting device can be electrically connected. Therefore, when the cold cathode fluorescent lamp 200 is attached to the lighting device, it is not necessary to solder the lead wires 204, and the attachment is easier than a cold cathode fluorescent lamp in which the power supply terminal 202 is not provided.

On the other hand, there is a cold cathode fluorescent lamp 300 including a so-called hollow electrode 303 including a bottomed cylindrical electrode body 301 and a lead wire 302 as shown in FIG. 12 (Patent Document 2). In the cold cathode fluorescent lamp 300, as indicated by an arrow in FIG. 12, since a discharge occurs inside the electrode body 301, the sputtered material scattered by the discharge hardly adheres to the inner surface of the glass bulb 304 and has a relatively long life. It is.
JP-A-7-220622 JP 2002-289138 A

  By the way, in the cold cathode fluorescent lamp 200 having the power supply terminal 202 as shown in FIG. 11, it is desirable to use a hollow electrode in order to extend the life, but if the hollow electrode is used, the lamp luminance is lowered. . The reason is as follows.

  When the electrode body 205 is rod-shaped, discharge occurs on the entire outer surface of the electrode body 205 as indicated by an arrow in FIG. 11, so a part of the discharge wraps around the lead wire 204 side and the lead wire 204 and its vicinity. Is heated. Therefore, even if the power supply terminal 202 joined to the lead wire 204 serves as a heat sink that lowers the temperature of the lead wire 204, the temperature of the lead wire 204 and the vicinity thereof does not drop excessively.

  On the other hand, in the case of the hollow electrode, since the discharge hardly flows to the lead wire 204 side and the lead wire 204 and its vicinity are rarely heated by the discharge, the heat radiation action of the power supply terminal 202 causes the lead wire 204 and its vicinity. The temperature is too low. As a result, a large amount of mercury vapor is collected around the lead wire 204, the mercury vapor in the discharge path is insufficient, and the lamp brightness is lowered.

  In view of the above problems, an object of the present invention is to provide a cold cathode fluorescent lamp having a sufficient lamp brightness while being easily mounted and having a long life.

  In order to solve the above problems, a cold cathode fluorescent lamp according to the present invention is provided on the outside of a glass bulb, a pair of hollow electrodes sealed at both ends of the glass bulb, and both ends of the glass bulb. The lead wire of the hollow electrode is joined to the lead wire, and the lead wire of the portion joined to the feed terminal is larger than the outer diameter of the lead wire on the sealing portion side with the glass bulb The puddle portion has a puddle portion, and the puddle portion is in close contact with both ends of the glass bulb, and the power supply terminal is formed on the outer surface of the glass bulb except for the joint portion with the lead wire. It is a thin film.

  Further, in the cold cathode fluorescent lamp according to the present invention, the lead wire is made of a material in which a sealing portion with the glass bulb is substantially the same as a coefficient of thermal expansion of the glass bulb, and the lead wire is accumulated. It is characterized in that at least a part of the part is made of nickel material or iron.

  Further, in the cold cathode fluorescent lamp according to the present invention, the lead wire is made of a material in which a sealing portion with the glass bulb is substantially the same as a coefficient of thermal expansion of the glass bulb, and the lead wire is accumulated. At least a part of the portion is formed by nickel plating.

  The cold cathode fluorescent lamp according to the present invention is characterized in that the pooled portion of the lead wire is embedded in the end portion of the glass bulb.

  In the cold cathode fluorescent lamp according to the present invention, the pooled portion of the lead wire has a circular cross section and is 1.5 to 4 times the outer diameter of the lead wire.

  In the cold cathode fluorescent lamp according to the present invention, the thin film has a thickness of 5 to 120 μm.

  Further, in the cold cathode fluorescent lamp according to the present invention, the lead wire is joined to the power supply terminal at a protruding portion protruding from the outer surface of the glass bulb toward the tube axis direction of the glass bulb, and the protruding The length of the portion in the tube axis direction is 1 mm or less.

  In the cold cathode fluorescent lamp according to the present invention, at least the joint portion of the power supply terminal is formed of solder.

  In the cold cathode fluorescent lamp according to the present invention, the glass bulb is composed of soda glass having a sodium oxide content of 3% to 20%.

  In the cold cathode fluorescent lamp according to the present invention, the glass bulb is composed of soda glass having a sodium oxide content of 5% to 20%.

  Furthermore, the backlight unit according to the present invention is characterized in that the cold cathode fluorescent lamp is mounted as a light source.

  The cold cathode fluorescent lamp according to the present invention is a thin film formed on the outer surface of the glass bulb except for the joint portion with the lead wire in the power supply terminal. For this reason, the power supply terminal has a small outer surface area, and has a smaller heat dissipation effect than a conventional power supply terminal. Accordingly, the temperature of the lead wire is unlikely to decrease, and mercury vapor is unlikely to collect around the lead wire, so that the phenomenon that the mercury vapor in the discharge path is insufficient and the lamp brightness of the cold cathode fluorescent lamp decreases is unlikely to occur. In addition, since the puddle portion larger than the outer diameter of the lead wire is in close contact with both ends of the glass bulb, the dimension from the puddle portion to the hollow electrode portion can be made constant, that is, the glass bulb facing the bottom portion of the hollow electrode. The effective light emission length can be increased by reducing the gap with the inner surface of the glass, and when the protruding part of the lead wire collides, the force applied to the pool part is absorbed at both ends of the glass bulb Therefore, it is possible to prevent leakage due to breakage of the end portion of the glass bulb to which the lead wire is sealed.

  Further, in the above configuration, at least a part of the pooled portion of the lead wire is formed of nickel material or nickel plating, so that the lead wire and the power supply terminal can be reliably connected with solder.

  Further, in the above-described configuration, the lead portion of the lead wire is embedded in the end portion of the glass bulb, so that when the lead wire protrudes to the outside, the force applied to the sump portion of the lead wire is reduced at both ends of the glass bulb. Therefore, leakage due to breakage of the glass bulb to which the lead wire is sealed can be prevented.

  Further, in the above configuration, the lead portion of the lead wire has a circular cross section and is 1.5 times to 4 times the outer diameter of the lead wire, so that the lead wire is further sealed. Leakage due to damage can be further prevented.

  In the above configuration, since the thin film of the power supply terminal has a thickness of 5 to 120 μm, if the thickness of the thin film is less than 5 μm, the thin film is easily peeled off from the glass bulb and cannot be actually used. On the other hand, if the thickness of the thin film is greater than 120 μm, the area of the outer surface of the power supply terminal becomes too large, and the heat dissipation effect of the power supply terminal becomes too large, so that the lead wire temperature is higher than that of the conventional cold cathode fluorescent lamp. Tends to be low. Therefore, there is a possibility that sufficient lamp brightness cannot be obtained.

  Further, in the above configuration, when the length of the protruding portion of the lead wire in the tube axis direction is 1 mm or less, in the cold cathode fluorescent lamp having a general size as described later, the protruding portion is the entire cold cathode fluorescent lamp. It does not protrude too much when viewed from the side. Therefore, it is possible to reduce the breakage of the glass bulb to which the lead wire is sealed due to the protruding portion colliding and bending, or due to the stress when the protruding portion is bent.

  Further, in the above configuration, when at least a joining portion of the power supply terminal is formed of solder, the power supply terminal can be formed by a known dipping method or the like. In particular, when the entire power supply terminal is formed of solder, it is easy to form the power supply terminal by the dipping method. Therefore, a cold cathode fluorescent lamp can be manufactured more easily and at a lower cost than a conventional power supply terminal that requires assembly of parts. In addition, since the solder generally has lower thermal conductivity than the iron / nickel alloy used for the cap-shaped power supply terminal, the heat radiation action of the power supply terminal can be further reduced. For this reason, the lamp brightness is less likely to decrease.

  Furthermore, in the said structure, a dark bulb start characteristic can be improved because the glass bulb | ball is comprised from the soda glass whose content rate of sodium oxide is 3% or more and 20% or less.

  Furthermore, in the above configuration, the glass bulb is made of soda glass having a sodium oxide content of 5% or more and 20% or less, so that the dark start-up time can be improved to about 1 second or less.

  Since the cold cathode fluorescent lamp is mounted as a light source in the backlight unit according to the present invention, the backlight unit has sufficient lamp brightness while being easily mounted on the lighting device and having a long life.

(Description of cold cathode fluorescent lamp)
Hereinafter, a cold cathode fluorescent lamp according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a partially broken perspective view showing a cold cathode fluorescent lamp according to an embodiment of the present invention, and FIG. 2 is an enlarged sectional view showing one end portion of the cold cathode fluorescent lamp. The cold cathode fluorescent lamp 1 is used as a light source of a backlight unit, and includes a glass bulb 10, a pair of hollow electrodes 20 sealed at both ends of the glass bulb 10, and both ends of the glass bulb 10. And a power supply terminal 30 provided outside.

The glass bulb 10 is obtained by processing a glass tube made of borosilicate glass (SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ —K ₂ O—TiO ₂ ) and has a total length of 730 mm. The glass bulb 10 includes a tubular glass bulb main body 11 and a sealing portion 12 formed using a pair of broken glass beads 11 a located on both sides in the longitudinal direction of the glass bulb main body 11. In addition, although the borosilicate glass was used for the material of the glass bulb | bulb 10, it is not restricted to this, For example, you may use soda glass. In consideration of improvement in workability and dark start-up characteristics of soda glass, the content of sodium oxide contained in the soda glass is preferably in the range of 3 (%) to 20 (%). If the content of sodium oxide is further 5 (%) or more, the dark start-up time under dark conditions is about 1 second or less. Conversely, if the content of sodium oxide exceeds 20 (%), the glass bulb will be whitened due to long-term use, leading to a decrease in brightness, and the strength of the glass bulb 10 itself may be reduced. This is because it occurs. In consideration of environmental measures, the soda glass has an alkali metal content within the range of 3 (%) to 20 (%), and the lead content is 0.1 (%). The following glass is preferable (so-called “lead-free glass”), and glass having a lead content of 0.01% or less is more preferable.

  The glass bulb body 11 has an annular shape in cross section, an outer diameter of 4 mm, an inner diameter of 3 mm, and a wall thickness of 0.5 mm. As shown in FIG. 2, the sealing portion 12 has a maximum width W of 2 mm in the tube axis A direction of the glass bulb 10, and the hollow electrode 20 is sealed.

  The configuration of the glass bulb 10 is not limited to the above configuration. However, in order to make the cold cathode fluorescent lamp 1 elongated, it is desirable that the glass bulb 10 has a small diameter and a thin wall. Therefore, generally, the outer diameter of the glass bulb body 11 is 1.8 mm (inner diameter 1.4 mm). It is preferably ˜6.0 mm (inner diameter: 5.0 mm).

A phosphor layer 13 is formed on the inner surface of the glass bulb 10. The phosphor layer 13 is, for example, a rare earth made of a red phosphor (Y ₂ O ₃ : Eu), a green phosphor (LaPO ₄ : Ce, Tb), and a blue phosphor (BaMg ₂ Al ₁₆ O ₂₇ : Eu, Mn). It is made of a phosphor. The glass bulb 10 is filled with, for example, about 1200 μg of mercury and a neon / argon mixed gas (Ne 95% + Ar 5%) of about 8 kPa (20 ° C.) as a rare gas.

  In addition, the structure of the fluorescent substance layer 13, mercury, and a noble gas is not limited to the said structure. For example, a neon / krypton mixed gas (Ne 95% + Kr 5%) may be enclosed as a rare gas. When neon / krypton mixed gas is used as the rare gas, lamp startability is improved, and the cold cathode fluorescent lamp 1 can be lit at a low voltage.

  The hollow electrode 20 is composed of a lead wire 22 fixed to the axis of a cylindrical glass bead 11a (shown by a broken line) and an electrode body 21 welded to one end of the lead wire 22, and the glass bulb 10 is provided with glass. The glass bulb 10 is hermetically sealed by inserting and sealing the beads 11a.

  The electrode body 21 is a nickel (Ni) material and has a bottomed cylindrical shape including a cylindrical portion 23 and a bottom portion 24. Note that the electrode body 21 is not limited to nickel but may be made of, for example, niobium (Nb), tantalum (Ta), or molybdenum (Mo).

  The cylindrical portion 23 has a total length of 5.2 mm, an outer diameter of 2.7 mm, an inner diameter of 2.3 mm, and a wall thickness of 0.2 mm. The hollow electrode 20 is disposed so that the tube axis of the tube portion 23 and the tube shaft of the glass bulb 10 are substantially aligned, and the interval between the outer peripheral surface of the tube portion 23 and the inner surface of the glass bulb 10 is the tube portion. 23 is substantially uniform over the entire outer periphery.

  Specifically, the interval between the outer peripheral surface of the cylindrical portion 23 and the inner surface of the glass bulb 10 is 0.15 mm. As described above, when the interval is narrow, the discharge does not enter the interval, and the discharge occurs only inside the hollow electrode 20. Therefore, the sputtered material that is scattered by the discharge is less likely to adhere to the inner surface of the glass bulb 10, and the cold cathode fluorescent lamp 1 has a long life. On the other hand, since the discharge does not flow to the lead wire 22 side, the lead wire 22 is not easily heated by the discharge.

  In addition, although the space | interval of the outer peripheral surface of the cylinder part 23 and the inner surface of the glass bulb 10 does not necessarily need to be 0.15 mm, in order to prevent discharge from entering the space | interval, it is 0.2 mm or less. Is preferred.

  The lead wire 22 is made of tungsten (W) made of nickel, which is substantially the same material as the thermal expansion coefficient of the glass bulb 10, and is made of nickel that is almost the same diameter as the internal lead wire 25 and easily adheres to solder or the like. The external lead wire 26 is welded and joined, and a thickened portion 27 larger than the outer diameter of the internal lead wire 25 is formed at the joint portion. And the pool part 27 which opposes the both end surfaces of the glass bulb 10 is provided so that it may closely contact the both ends of the glass bulb 10 (that is, the external lead wire 26 and the pool part 27 are the outer surfaces of the glass bulb 10. Located outside). With this configuration, the dimension from the pool portion 27 to the hollow electrode 20 can be made constant. In other words, the gap ε between the bottom of the hollow electrode 20 and the inner surface of the glass bulb 10 facing it is effectively reduced to about 0.5 mm. The light emission length L can be increased, and when the protruding portion of the external lead wire 26 collides with the outside, the force applied to the pool portion 27 is absorbed at both ends of the glass bulb 10, so that the internal lead wire 25 It is possible to prevent leakage due to breakage of the sealing portion 12 of the glass bulb 10 to which is sealed. The pool portion 27 is formed of the same nickel material as that of the external lead wire 26. However, the present invention is not limited to this, and for example, a Fe—Ni alloy, a Cu—Ni alloy, or a material of a dumet wire can be considered.

  The internal lead wire 25 has a substantially circular cross section, a total length of 3 mm, and a wire diameter of 0.8 mm. Further, the inner lead wire 25 is sealed at the end portion on the thickened portion 27 side to the sealing portion 12 of the glass bulb 10, and the end portion opposite to the outer lead wire 26 side is at the bottom portion 24 of the electrode body 21. It is joined at the approximate center of the outer surface.

  The external lead wire 26 and the pool portion 27 are protruding portions that protrude from the outer surface of the glass bulb 10 toward the tube axis A, and are joined to the power supply terminal 30. The external lead wire 26 and the pool portion 27 have a substantially circular cross section and a total total length σ of 1 mm, and the axis of the external lead wire 26 and the tube axis A of the glass bulb 10 are substantially aligned. .

  The total length σ of the external lead wire 26 and the pool portion 27 in the tube axis A direction is preferably 1 mm or less. In addition, the outer diameter of the pool portion 27 is preferably 1.5 to 4 times the outer diameter of the internal lead wire 25 in consideration of damage to the sealing portion 12 and part price. As described above, in order to make the cold cathode fluorescent lamp 1 elongated, the outer diameter of the glass bulb body 11 is preferably in the range of 1.8 mm to 6.0 mm. 1, if the total length σ of the external lead wire 26 and the padding portion 27 in the tube axis A direction is 1 mm or less, the external lead wire 26 does not protrude excessively when viewed from the cold cathode fluorescent lamp 1 as a whole. Therefore, the external lead wire 26 does not hit the outside, and the external lead wire 26 is hardly bent or the sealing portion 12 is damaged. For example, when the cold cathode fluorescent lamp 1 is attached to the backlight unit 100, the external lead wire 26 hits the backlight unit 100 and bends, or the sealing portion 12 breaks due to the stress applied to the external lead wire 26 when it hits. Is less likely to occur.

  The power supply terminal 30 is provided at both ends of the glass bulb 10 so as to cover both ends. The power supply terminal 30 is made of solder, and includes a joining portion 31 joined to the external lead wire 26 and the pool portion 27, and a thin film portion 32 as a portion other than the joining portion.

  The joint portion 31 is a portion where the power supply terminal 30 is electrically connected to the internal lead wire 25 and has a substantially conical shape in appearance. For this reason, the area of the outer surface of the joint portion 31 is small despite completely covering the entire outer surface of the external lead wire 26. Therefore, since the area of the outer surface of the power supply terminal 30 is small and the heat dissipation action is small, the temperature of the internal lead wire 25 is not easily lowered. In addition, since the external lead wire 26 is completely covered with the power supply terminal 30, there is little possibility that the external lead wire 26 is bent or stress is applied to the external lead wire 26 and the sealing portion 12 is damaged. The area of the outer surface of the joint portion 31 is preferably as small as possible.

  The thin film portion 32 is formed in a predetermined region on the sealing portion 12 side on the outer surface of the glass bulb body 11 and a predetermined region on the glass bulb body 11 side on the outer surface of the sealing portion 12. In order to suppress the heat radiation effect of the power supply terminal 30 to be small, it is preferable that the region where the thin film portion 32 is formed is as narrow as possible.

  The power supply terminal 30 can be formed by a known dipping method (for example, Japanese Patent Application Laid-Open No. 2004-146351). A method for forming the power supply terminal 30 by the dipping method will be briefly described. For example, the sealing portion 12 of the glass bulb 10 to which the hollow electrode 20 is sealed is immersed in the molten solder in the melting tank. When the sealing portion 12 is immersed in the molten solder, ultrasonic waves may be applied. Since such a dipping method can form the power supply terminal 30 easily and inexpensively, the cold cathode fluorescent lamp 1 can be manufactured inexpensively.

  The power supply terminal 30 may be formed by a method other than the dipping method. For example, you may form by methods, such as vapor deposition and plating.

  The configuration of the power supply terminal 30 is not limited to the above configuration, and for example, a configuration as shown in Modifications 1 to 3 can be considered. Note that the cold cathode fluorescent lamps according to the first to third modifications basically have the same configuration as that of the cold cathode fluorescent lamp 1 according to the present embodiment except that the configurations of the power supply terminal and the electrodes are different. Therefore, common parts are denoted by the same reference numerals as in the present embodiment, description thereof is omitted, and only different parts are described.

  FIG. 3 is an enlarged cross-sectional view showing one end of the cold cathode fluorescent lamp according to the first modification. The power supply terminal 51 of the cold cathode fluorescent lamp 50 shown in FIG. 3 includes a joint portion 52 and a thin film portion 53. The lead wire 22 is formed, for example, by welding a pool portion 27 of nickel material to one end of an internal lead wire 25 of tungsten material. The joining portion 52 has a substantially hemispherical shape in appearance and covers the entire outer surface of the pool portion 27 of the lead wire 22.

  According to this configuration, the pool portion 27 is completely covered and hidden by the joint portion 52, and the end of the cold cathode fluorescent lamp 50 is smoothly rounded. Therefore, the end of the cold cathode fluorescent lamp 50 is exposed to the outside. Even if it collides, there is little possibility that the external lead wire 26 is bent or the sealing portion 12 is damaged.

  In addition, although the thickening part 27 was formed with the nickel material, it does not restrict to this, For example, after integrally forming with the same material as the internal lead wire 25 of tungsten material, one part or all part of the surface of the thickening part 27 is formed. It may be formed by nickel plating which is easy to solder.

  FIG. 4 is an enlarged cross-sectional view showing one end of a cold cathode fluorescent lamp according to Modification 2. The power supply terminal 61 of the cold cathode fluorescent lamp 60 shown in FIG. 4 includes a joint portion 62 and a thin film portion 63. The lead wire 22 is formed, for example, by welding a pool portion 27 of nickel material to one end of an internal lead wire 25 of tungsten material. Further, the pool portion 27 is embedded in the end portion of the glass bulb 10. The joining portion 62 covers the outer surface of the pool portion 27 of the lead wire 22 with a thin film. The thickness of the thin film is 10 μm, which is the same as that of the thin film portion 63.

  According to this configuration, since the pool portion 27 is embedded in the end portion of the glass bulb 10, the pool portion 27 does not collide with the outside, and the sealing portion 12 can be prevented from being damaged. Moreover, by using a thin film for the entire power supply terminal 30, the amount of solder used can be reduced, and the cold cathode fluorescent lamp 60 can be manufactured at a lower cost.

  In addition, in the said modification 2, the whole pool part 27 is completely embedded by the glass bulb 10 edge part, However, Not only this but a part of the pool part 27 may be embedded. That is, the greater the amount of the buried portion 27 embedded in the end portion of the glass bulb 10, the lower the probability that it will collide with the outside.

  FIG. 5 is an enlarged cross-sectional view showing one end portion of a cold cathode fluorescent lamp according to Modification 3, and FIG. 5 is a perspective view showing a thin film member constituting a power supply terminal. The power supply terminal 71 of the cold cathode fluorescent lamp 70 shown in FIG. 5 includes a solder joint portion 72 and a thin film member 73 made of iron / nickel alloy as a thin film portion. As described above, the power supply terminal 71 does not necessarily have to be entirely made of the same material.

  As shown in FIG. 6, the thin film member 73 is a cylindrical body having a wall thickness of 120 μm and having a substantially C-shaped cross section, and is externally fitted to the end of the glass bulb 10. The inner diameter of the thin film member 73 is slightly smaller than the outer diameter of the glass bulb 10, and the thin film member 73 is provided with a slit 74. Therefore, even if a slight dimensional error occurs between the inner diameter of the thin film member 73 and the outer diameter of the glass bulb 10, the inner surface of the thin film member 73 is designed to be in close contact with the outer surface of the glass bulb 10.

  Note that the thin film member 73 is not limited to a cylindrical body having a substantially C-shaped cross section, and may be formed by providing a slit in a polygonal body such as a substantially triangular or substantially quadrangular cross section or an elliptical cylindrical body. Moreover, the case where a slit is not provided is also considered.

  The total total length σ of the external lead wire 26 and the pool portion 27 is 1 mm, and the length L1 of the thin film member 73 in the portion containing the external lead wire 26 and the pool portion 27 is 1.5 mm. The joining portion 72 is a thick region (region L1 region) of the external lead wire 26 and the pool portion 27.

  When the power supply terminal 71 is configured as described above, since the external lead wire 26 does not protrude outward, no stress is applied to the sealing portion 12 of the glass bulb 10 even if the power supply terminal 71 is struck outside. Is hard to break.

  Note that the material forming the power supply terminals 30, 51, 61 is not limited to solder, and may be any material having at least conductivity. However, it is preferable that the material has a low thermal conductivity so that the heat radiation action of the power supply terminals 30, 51, 61 does not increase.

  In general, solder is suitable as a material for the power supply terminals 30, 51, 61 because it has good conductivity, low thermal conductivity, and low price. In particular, solder mainly composed of tin (Sn), tin-indium (In) alloy, tin-bismuth (Bi) alloy, or the like is more preferable because it can form the power supply terminal 30 with high mechanical strength. is there. A solder obtained by adding at least one of antimony (Sb), zinc (Zn), aluminum (Al), gold (Au), iron (Fe), platinum (Pt) and palladium (Pd) to glass is used. Therefore, it is possible to form the power supply terminals 30, 51, 61 that are difficult to peel off from the glass bulb 10, which is more preferable. In addition, solder containing no lead is suitable because it can produce the cold cathode fluorescent lamp 1 in consideration of the environment.

  The cold cathode fluorescent lamp 1 is operated at a lighting frequency of 40 to 120 kHz and a lamp current of 3.5 to 8.5 mA.

  The cold cathode fluorescent lamp according to the present invention has been specifically described above based on the embodiment, but the cold cathode fluorescent lamp according to the present invention is not limited to the above embodiment. For example, the cold cathode fluorescent lamp is not limited to a straight tube shape, and may be a bent cold cathode fluorescent lamp such as a U-shape.

  Further, it is conceivable to cover the outer surface of the power supply terminal with a material having conductivity and low thermal conductivity. For example, it is conceivable to cover the outer surface of the solder power supply terminal with a cylindrical member made of tantalum as shown in FIG. Thereby, it is possible to make it difficult to peel off the power feeding terminal.

(Explanation of experiment)
The temperature characteristics of the cold cathode fluorescent lamp were measured, and the heat dissipation action of the power supply terminal was examined. FIG. 7 shows the temperature characteristics of the cold cathode fluorescent lamp.

  In FIG. 7, the cold cathode fluorescent lamp of the example has the same configuration as the cold cathode fluorescent lamp 1 according to the present embodiment except that the thickness of the thin film portion 32 of the power supply terminal 30 is 50 μm.

  As shown in FIG. 12, the cold cathode fluorescent lamp of Comparative Example 1 is a cold cathode fluorescent lamp not provided with a power feeding terminal, and the cold cathode fluorescent lamp 1 according to the present embodiment except for the structure related to the electrode and the power feeding terminal. It has the same configuration as.

  In the experiment, for each cold cathode fluorescent lamp, the surface temperature of the glass bulb in the tube axis direction center (hereinafter referred to as “tube center”) and the surface temperature near the electrode of the glass bulb were measured.

  The cold cathode fluorescent lamp of the example and the cold cathode fluorescent lamp of Comparative Example 1 have the same temperature in the vicinity of the electrode and in the center of the tube, and the temperature difference between the temperature in the vicinity of the electrode and the temperature in the center of the tube is also It is about the same. Accordingly, the mercury vapor collected in the vicinity of the electrodes and in the discharge path is approximately the same, and the lamp luminance is also approximately the same. It can be assumed that this is because the heat dissipation action is comparable. From this result, it can be seen that when the film thickness of the thin film portion of the power supply terminal is 50 μm or less, a lamp brightness comparable to that of a cold cathode fluorescent lamp not provided with the power supply terminal can be obtained.

  FIG. 8 is a graph showing the relationship between the film thickness of the thin film portion of the power supply terminal and the temperature near the electrode in the cold cathode fluorescent lamp of the example. As shown in FIG. 8, when the thickness of the thin film portion 32 of the power supply terminal 30 becomes 120 μm, the temperature difference between the vicinity of the electrode 20 and the central portion of the tube disappears. Therefore, the film thickness of the thin film portion 32 is preferably 120 μm or less so that the temperature in the vicinity of the electrode 20 does not become lower than the central portion of the tube. In the present invention, the thin film is defined as a film having a film thickness of 120 μm or less.

(Description of backlight unit)
FIG. 9 is an exploded perspective view showing a schematic configuration of a backlight unit and the like according to an embodiment of the present invention, and FIG. 10 is a diagram for explaining a mounting state of the cold cathode fluorescent lamp.

  As shown in FIG. 9, a backlight unit 100 according to an embodiment of the present invention is a direct-type backlight unit for a liquid crystal television, and its structure is basically the same as that of a conventional backlight unit. Follow.

  The backlight unit 100 includes an envelope 110, a diffusion plate 120, a diffusion sheet 130, and a lens sheet 140, and is used by being disposed on the back surface of the liquid crystal panel 150.

  The envelope 110 is a box made of white polyethylene terephthalate (PET) resin. As shown in FIG. 10, the envelope 110 includes a substantially rectangular reflecting plate 111 and side plates 112 to 115 surrounding the periphery of the reflecting plate 111. Become. A plurality of cold cathode fluorescent lamps 1 are arranged inside the envelope 110, and light from the cold cathode fluorescent lamps 1 is emitted toward the diffusion plate 120 from the opening 116 of the envelope 110.

  A set of sockets 160 is disposed on the reflecting plate 111 at positions corresponding to the mounting positions of the cold cathode fluorescent lamps 1. Each socket 160 is formed by bending a plate made of a copper alloy such as phosphor bronze or aluminum, for example, and is connected to a pair of sandwiching pieces 161 and 162 and connecting the sandwiching pieces 161 and 162 at a lower edge. It consists of a piece 163. The sandwiching pieces 161 and 162 are provided with recesses that match the outer shape of the cold cathode fluorescent lamp 1. When the cold cathode fluorescent lamp 1 is fitted in the recesses, the sandwiching pieces 161 and 162 are cooled by the leaf spring action. The cathode fluorescent lamp 1 is held in the socket 160, and the socket 160 and the power supply terminal 30 are electrically connected. The cold cathode fluorescent lamp 1 attached to the backlight unit 100 is supplied with power from a lighting circuit (not shown) of the backlight unit 100 via a socket 160.

  The diffusion plate 120 is a plate made of polycarbonate (PC) resin, and is disposed so as to close the opening 116 of the envelope 110. The diffusion sheet 130 is made of a polycarbonate resin, and the lens sheet 140 is made of an acrylic resin, and is disposed so as to be sequentially overlapped with the diffusion plate 120.

  Although the backlight unit according to the present invention has been specifically described above based on the embodiments, the backlight unit according to the present invention is not limited to the above embodiments. For example, the present invention is not limited to a direct-type backlight unit, but an edge light system (also referred to as a satellite system or a light guide plate system) in which a light guide plate is disposed on the back surface of a liquid crystal panel and a cold cathode fluorescent lamp 1 is disposed on an end surface of the light guide plate. ) Backlight unit.

  The cold cathode fluorescent lamp according to the present invention can be used as a light source of a backlight unit, and the backlight unit according to the present invention can be used for a liquid crystal television or a liquid crystal display.

The partially broken perspective view which shows the cold cathode fluorescent lamp concerning one Embodiment of this invention Expanded sectional view showing one end of the cold cathode fluorescent lamp The expanded sectional view which shows the one end part of the cold cathode fluorescent lamp which concerns on the modification 1 The expanded sectional view which shows the one end part of the cold cathode fluorescent lamp which concerns on the modification 2 The expanded sectional view which shows the one end part of the cold cathode fluorescent lamp which concerns on the modification 3 The perspective view which shows the thin film member which comprises an electric power feeding terminal Diagram showing temperature characteristics of cold cathode fluorescent lamp The figure which shows the relationship between the film thickness of the thin film portion of the power supply terminal and the temperature near the electrode The disassembled perspective view which shows schematic structure, such as a backlight unit concerning one Embodiment of this invention. The figure explaining the attachment state of a cold cathode fluorescent lamp Sectional drawing which shows the edge part of the conventional cold cathode fluorescent lamp provided with the cap-shaped electric power supply terminal Sectional drawing which shows the edge part of the conventional cold cathode fluorescent lamp provided with the hollow electrode

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cold cathode fluorescent lamp 10 Glass bulb 20 Hollow electrode 22 Lead wire 27 Bump part 30 Feeding terminal 31 Joint part

Claims (11)

A glass bulb, a pair of hollow electrodes sealed at both ends of the glass bulb, and a power supply terminal provided outside the both ends of the glass bulb and joined to a lead wire of the hollow electrode, The lead wire of the portion joined to the power supply terminal has a bulge portion larger than the outer diameter of the lead wire on the sealing portion side with the glass bulb, and the bulge portion of the glass bulb A cold-cathode fluorescent lamp characterized by being in close contact with both ends, wherein the power supply terminal is a thin film formed on the outer surface of the glass bulb except for the joint portion with the lead wire. As for the material of the lead wire, the sealing portion with the glass bulb is formed of a material substantially the same as the thermal expansion coefficient of the glass bulb, and at least a part of the puddle portion of the lead wire is formed of a nickel material. The cold cathode fluorescent lamp according to claim 1, wherein: The lead wire material is formed such that a sealing portion with the glass bulb is formed of a material substantially the same as the thermal expansion coefficient of the glass bulb, and at least a part of the bulge portion of the lead wire is formed of nickel plating. The cold cathode fluorescent lamp according to claim 1, wherein: The cold cathode fluorescent lamp according to any one of claims 1 to 3, wherein a pooled portion of the lead wire is embedded in an end portion of the glass bulb. The cold cathode according to any one of claims 1 to 4, wherein the pool portion of the lead wire has a circular cross section and is 1.5 to 4 times the outer diameter of the lead wire. Fluorescent lamp. The cold cathode fluorescent lamp according to claim 1, wherein the thin film has a thickness of 5 to 120 μm. The lead wire is joined to the power supply terminal at a protruding portion that protrudes from the outer surface of the glass bulb toward the tube axis direction of the glass bulb, and the length of the protruding portion in the tube axis direction is 1 mm or less. The cold cathode fluorescent lamp according to claim 1, wherein: The cold cathode fluorescent lamp according to claim 1, wherein at least the joining portion of the power supply terminal is formed of solder. 9. The cold cathode fluorescent lamp according to claim 1, wherein the glass bulb is made of soda glass having a sodium oxide content of 3% or more and 20% or less. 9. The cold cathode fluorescent lamp according to claim 1, wherein the glass bulb is made of soda glass having a sodium oxide content of 5% to 20%. A backlight unit comprising the cold cathode fluorescent lamp according to claim 1 as a light source.

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