JP2007157565A - Lighting device, backlight unit, and liquid crystal tv - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lighting device of which harness treatment is reduced like an almost U-shaped cold cathode fluorescent lamp, unevenness of brightness in a longitudinal direction of the lamp (left side and right side in an envelope), prevented from breakage of a sealing part or the like of the cold cathode fluorescent lamp, capable of detaching the cold cathode fluorescent lamp by one touch, and to provide a backlight unit and a liquid crystal TV. <P>SOLUTION: The lighting device 50 is composed of straight tube-shaped cold cathode fluorescent lamps 100 having power supply terminals 104, 105 connected to a lead wire of an electrode, conductive lamp holders 15, 16 arranged on a case 13 side to which the power supply terminals of the cold cathode fluorescent lamp 100 are connected, and a lighting control circuit 60 lighting the cold cathode fluorescent lamp 100 connected to the lamp holders 15, 16. The lamp holder at one side, to which adjacent two cold cathode fluorescent lamps 100 are connected, is connected to grounding side, and the lamp holder 16 at the other side is connected to high voltage side of the lighting circuit. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a lighting device, a backlight unit, and a liquid crystal television used for an LCD (liquid crystal display) device or the like.

  A direct-type backlight unit uses a plurality of lamps as light sources and uses a straight-tube or substantially U-shaped cold cathode fluorescent lamp, and is used in, for example, an LCD device. The use of a substantially U-shaped cold cathode fluorescent lamp in the backlight unit can reduce the number of lamps by half compared to the case of using a straight tube type cold cathode fluorescent lamp, and the cold cathode fluorescent lamp. This is because the harness processing for connecting the electrode lead wires outside both ends of the lamp and the lead wires from the lighting device for lighting the cold cathode fluorescent lamp with solder or the like can be reduced in half.

  In a general backlight unit, cold cathode fluorescent lamps with an approximately U-shape are arranged in parallel in an envelope so that the ends are aligned on either the left or right side, and light is applied to the electrode lead wires at both ends of each lamp. A high voltage of several kV is applied by the device.

For example, Patent Document 1 is known as prior art document information relating to the invention of this application.
JP 2004-327328 A

  However, the above backlight unit has a larger amount of light emitted from the bent portion of the lamp than the amount of light emitted from the end side of the substantially U-shaped cold cathode fluorescent lamp. However, there is a problem that uneven brightness occurs.

  In addition, the substantially U-shaped cold cathode fluorescent lamp can reduce the number of lamps by half compared to the case of adopting a straight tube type cold cathode fluorescent lamp, but the lamp length becomes longer than twice. Therefore, particularly at one end of the cold cathode fluorescent lamp in the lamp length direction (the end on the side that sucks up the phosphor liquid in the phosphor coating process), the phosphor film becomes extremely thin at the time of manufacture, and the luminance unevenness at both ends of the lamp There is a problem.

  Further, in order to connect the electrode lead wires outside the both ends of the cold cathode fluorescent lamp and the lead wires from the lighting device with solder or the like, a plurality of cold cathode fluorescent lamps are attached to the backlight unit when installed in the backlight unit. The electrode lead wire collides with the housing of the unit, the load is applied to the sealing part and the bent part of the glass bulb to which the electrode lead wire in the cold cathode fluorescent lamp is sealed, and the sealing part or bent part of the glass bulb is There is a problem of breakage and leakage and a problem that the harness processing is complicated.

  In view of the above problems, the present invention reduces the unevenness of the brightness in the lamp length direction (both left and right sides in the envelope) in addition to reducing the harness processing in the same manner as the substantially U-shaped cold cathode fluorescent lamp. It is an object of the present invention to provide a lighting device, a backlight unit, and a liquid crystal television that can prevent a cathode fluorescent lamp sealing portion from being damaged and can attach and detach a cold cathode fluorescent lamp with a single touch.

  In order to achieve the above object, in the lighting device according to claim 1, a pair of electrodes sealed at both ends of a straight tubular glass bulb and outside the both ends of the glass bulb, the lead of the electrode is provided. A cold cathode fluorescent lamp provided with a power supply terminal joined to a wire, a conductive lamp holder provided on the housing side so that power supply terminals at both ends of the glass bulb are connected, and connected to the lamp holder A lighting device comprising a lighting circuit for lighting the cold cathode fluorescent lamp, wherein at least one of the lamp holders connected to the power supply terminals of the two cold cathode fluorescent lamps connected to the ground side, Each of the other lamp holders is connected to the high voltage side of the lighting circuit.

  The lighting device according to claim 2 is characterized in that a phase difference between voltages applied to two adjacent lamp holders connected to the high voltage side of the lighting circuit is approximately 0 degrees.

  The lighting device according to claim 3 is characterized in that the electrode of the cold cathode fluorescent lamp is provided with cylindrical hollow electrodes at both ends in the glass bulb.

  In the lighting device according to claim 4, the cold cathode fluorescent lamp has a flat cross section of the light extraction portion in the positive column light emitting portion of the glass bulb, and crosses at least the hollow electrode region of the glass bulb. The surface is circular, and the length of the flat light extraction portion of the glass bulb is longer than the circular length of the hollow electrode region.

  The lighting device according to claim 5 is characterized in that the power supply terminal is a thin film formed on an outer surface of the glass bulb except for a joint portion with the lead wire.

  The lighting device according to claim 6 is characterized in that the thin film has a thickness of 5 to 120 μm.

  The lighting device according to claim 7 is characterized in that at least the joint portion of the thin film is formed of solder.

  In the lighting device according to claim 8, the thin film includes a main body layer mainly composed of silver or copper formed on an outer surface of the glass bulb, and a coating layer or a thin wall laminated on the outer side of the main body layer. It is formed with a metal member.

  In the lighting device according to claim 9, the power supply terminal is configured such that an end portion of the coating layer or a thin metal member on the glass bulb center side is positioned from the position of the main body layer end portion on the glass bulb center side. It is characterized in that it is installed at an interval on the end side.

  In the lighting device according to claim 10, the film thickness of the power supply terminal including the main body layer and a coating layer or a thin metal member laminated on the outside of the main body layer is 5 to 120 μm. To do.

  In the lighting device according to an eleventh aspect, the thickness of the edge portion of the power supply terminal becomes thinner as the edge approaches the edge.

  The lighting device according to a twelfth aspect is characterized in that an end edge portion of the power supply terminal has an arcuate shape on the outer side, and the thickness thereof becomes thinner toward the end edge.

  In the lighting device according to a thirteenth aspect, the coating layer is mainly composed of solder.

  In the lighting device according to claim 14, the lead wire of the portion joined to the power supply terminal has a pooled portion larger than the outer diameter of the lead wire on the sealing portion side with the glass bulb, and The puddle portion is in close contact with both end portions of the glass bulb.

  In the lighting device according to claim 15, the material of the lead wire is such that a sealing portion with the glass bulb is formed of a material substantially the same as a thermal expansion coefficient of the glass bulb, and at least a stagnant portion of the lead wire. A part is formed of nickel material or nickel plating.

  In the lighting device according to a sixteenth aspect, the pool portion of the lead wire is embedded in the end portion of the glass bulb.

  The lighting device according to claim 17 is characterized in that 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.

  In the lighting device according to claim 18, the lead wire is joined to the power supply terminal at a protruding portion that protrudes from an outer surface of the glass bulb toward a tube axis direction of the glass bulb, and The length in the tube axis direction is 1 mm or less.

  The backlight unit according to claim 19 is a backlight unit used for a liquid crystal display, and includes the lighting device according to any one of claims 1 to 18.

  A liquid crystal television according to a twentieth aspect is a liquid crystal television including a direct type backlight unit, wherein the backlight unit is the backlight unit according to the nineteenth aspect.

  According to the lighting device of the first aspect of the present invention, at least one of the power supply terminals in the two adjacent straight-tube cold cathode fluorescent lamps is connected via the conductive lamp holder. Like the U-shaped cold-cathode fluorescent lamp, in addition to reducing harness processing, it reduces brightness unevenness in the lamp length direction (both left and right sides of the envelope), and damages the cold-cathode fluorescent lamp seal and other parts. The cold cathode fluorescent lamp can be connected and installed in the unit housing with a single touch. In addition, since the straight tubular cold cathode fluorescent lamps having electrodes at both ends are arranged, for example, in the vertical direction, the electrodes serving as heat sources do not concentrate on one side, so there is a temperature difference between the left and right sides of the housing. As a result, the luminance unevenness of the backlight unit due to the influence of the mercury vapor pressure of the lamp can be suppressed.

  According to the lighting device of the second aspect of the present invention, the phase difference between the voltages applied to the two adjacent lamp holders connected to the high voltage side of the lighting circuit is approximately 0 degrees (same potential). Compared to a voltage having a phase difference of approximately 180 degrees, the interval between two adjacent straight-tube cold cathode fluorescent lamps can be reduced.

  According to the lighting device of the third aspect of the present invention, since the cold cathode fluorescent lamp electrode is a hollow electrode, sputtering from the electrode to the inner surface of the glass bulb can be reduced, and mercury consumption can be reduced.

  According to the lighting device of the fourth aspect of the present invention, the cross section of the light extraction portion of the cold cathode fluorescent lamp has a flat shape, so that the outer peripheral surface area is increased as compared with the conventional straight tube lamp and the coldest spot temperature is reduced. An excessive rise can be suppressed, and the flat inner diameter of the short inner diameter is shorter than that of a conventional straight tube lamp having a tube inner diameter comparable to that of the longer inner diameter. Therefore, from the center of the positive column plasma space to the inner wall of the tube. The distance can be effectively kept short. For this reason, even if the lamp current is increased as compared with the prior art, it is possible to make it difficult to reduce the light emission efficiency.

  According to the lighting device according to claim 5 of the present invention, the power supply terminal of the cold cathode fluorescent lamp is a thin film formed on the outer surface of the glass bulb except for the joint portion with the lead wire of the electrode. 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.

  According to the lighting device of the sixth aspect of the present invention, the thin film preferably 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 used in actual use. 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 consequently the heat dissipation action of the power supply terminal becomes too large. It tends to be lower than the lamp. Therefore, there is a possibility that sufficient lamp brightness cannot be obtained.

  According to the lighting device of the seventh aspect of the present invention, when at least the joint 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.

  According to the lighting device according to claim 8 of the present invention, the main body layer of the power supply terminal is mainly composed of a metal having a low electrical resistance such as silver or copper, and therefore has high conductivity, and is provided outside the main body layer. Since a coating layer or a thin metal member is laminated, the main body layer is not easily exposed to the atmosphere, and silver sulfide and copper oxidation are unlikely to occur. As a result, the connectivity between the power supply terminal and the electrode lead wire can be improved. In addition, when the cold cathode fluorescent lamp is mounted on the lamp holder, it is possible to make it difficult for the power supply terminal to be scratched or cracked.

  According to the lighting device according to claim 9 of the present invention, the end portion of the coating layer or the thin metal member on the glass bulb center side in the power supply terminal is located at the end of the glass bulb from the position of the main body layer end portion on the glass bulb center side. It is possible to suppress the occurrence of corona discharge when the lamp is lit between the coating layer or metal member and the glass bulb, and to reduce the amount of ozone generated. can do.

  According to the lighting device of claim 10 of the present invention, it is preferable that the power supply terminal has a film thickness of 5 to 120 μm between the main body layer and the coating layer laminated outside the main body layer. When the film thickness of the power supply terminal is thinner than 5 μm, the thin film is easily peeled off from the glass bulb and cannot be used in actual use. On the other hand, if the film thickness of the power supply terminal is thicker 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. It tends to be lower than fluorescent lamps. Therefore, there is a possibility that sufficient lamp brightness cannot be obtained.

  According to the lighting device of the eleventh aspect of the present invention, when the main component of the coating layer of the power supply terminal is solder, the coating layer is unlikely to corrode or deteriorate. As a result, the life of the power supply terminal can be extended.

  According to the lighting device of the twelfth aspect of the present invention, the thickness of the end edge portion of the power supply terminal is reduced as it approaches the end edge, so that the lamp is interposed between the end edge portion of the power supply terminal and the glass bulb. The generation of corona discharge during lighting can be suppressed, and the amount of ozone generated can be reduced.

  According to the lighting device of the thirteenth aspect of the present invention, the edge portion of the power supply terminal has an arcuate shape on the outside, and the thickness of the end portion of the power supply terminal decreases as the thickness approaches the edge. The strength is increased, and the power supply terminal is difficult to peel off from the outer surface of the glass bulb.

  According to the lighting device of the fourteenth aspect of the present invention, in the cold cathode fluorescent lamp, since the thickened portion larger than the outer diameter of the lead wire is in close contact with both end portions of the glass bulb, the hollow electrode portion extends from the thickened portion. Can be made constant, that is, the gap between the bottom of the hollow electrode and the inner surface of the glass bulb facing the surface can be reduced to increase the effective light emission length, and the protruding portion of the lead wire collides with the outside. At this time, since the force applied to the pool portion is absorbed at both ends of the glass bulb, leakage due to breakage of the end of the glass bulb to which the lead wire is sealed can be prevented.

  According to the lighting device of the fifteenth aspect of the present invention, in the cold cathode fluorescent lamp, at least a part of the pooled portion of the lead wire is formed of a nickel material or nickel plating, so that the lead wire, the power supply terminal, Can be reliably connected by soldering.

  According to the lighting device of the sixteenth aspect of the present invention, in the cold cathode fluorescent lamp, the pooled portion of the lead wire is embedded in the end portion of the glass bulb, so that the protruding portion of the lead wire collides with the outside. In this case, since the force applied to the pool portion is further absorbed at both ends of the glass bulb, it is possible to prevent leakage due to breakage of the glass bulb to which the lead wire is sealed.

  According to the lighting device of the seventeenth aspect of the present invention, in the cold cathode fluorescent lamp, the stagnant portion of the lead wire has a circular cross section, and is 1.5 to 4 times the outer diameter of the lead wire. As a result, it is possible to further prevent leakage due to breakage of the glass bulb to which the lead wire is sealed.

  According to the lighting device of the eighteenth aspect of the present invention, in the cold cathode fluorescent lamp, when the length of the protruding portion of the lead wire in the tube axis direction is 1 mm or less, a cold lamp having a general size as described later is used. In the cathode fluorescent lamp, the protruding portion does not protrude excessively when viewed from the whole cold cathode fluorescent lamp. 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.

  According to the backlight unit of the nineteenth aspect of the present invention, by providing the lighting device, in addition to reducing the harness processing in the same manner as the substantially U-shaped cold cathode fluorescent lamp, the lamp length direction (inside the envelope) Brightness unevenness on both the left and right sides) and the damage of the cold cathode fluorescent lamp sealing portion and the like can be prevented, and the cold cathode fluorescent lamp can be connected and mounted in the case of the unit with one touch. In addition, since the straight tubular cold cathode fluorescent lamps having electrodes at both ends are arranged, for example, in the vertical direction, the electrodes serving as heat sources do not concentrate on one side, so there is a temperature difference between the left and right sides of the housing. As a result, the luminance unevenness of the backlight unit due to the influence of the mercury vapor pressure of the lamp can be suppressed.

  According to the liquid crystal television of the twentieth aspect of the present invention, by providing the lighting device, in addition to reducing the harness processing in the same manner as the substantially U-shaped cold cathode fluorescent lamp, the lamp length direction (inside the envelope) The brightness unevenness on both the left and right sides is reduced, and the cold cathode fluorescent lamp sealing part and the like are prevented from being damaged, and the cold cathode fluorescent lamp can be connected and mounted in the unit housing with one touch. In addition, since the straight tubular cold cathode fluorescent lamps having electrodes at both ends are arranged, for example, in the vertical direction, the electrodes serving as heat sources do not concentrate on one side, so there is a temperature difference between the left and right sides of the housing. As a result, the luminance unevenness of the backlight unit due to the influence of the mercury vapor pressure of the lamp can be suppressed.

(Embodiment 1)
FIG. 1 is a diagram showing an outline of a liquid crystal television which is one of the liquid crystal displays according to Embodiment 1 of the present invention.

  A liquid crystal television 10 shown in FIG. 1 is, for example, a 32-inch liquid crystal television, and includes a liquid crystal screen unit 11 and a backlight unit 12.

  A liquid crystal screen unit 11 that is a diagram showing an outline of a liquid crystal television that is one of the liquid crystal displays in Embodiment 1 of the present invention includes a color filter substrate, a liquid crystal, a TFT substrate, a drive module, and the like (not shown). A color image is formed based on an external image signal.

  FIG. 2 is a perspective view showing the backlight unit 12, and is a view showing the internal structure by cutting out a part of the front panel 21.

  The backlight unit 12 includes, for example, a plurality of cold-cathode fluorescent lamps 100 (hereinafter referred to as “lamps 100”), a housing 13 having openings and housing these lamps 100, and openings of the housing 13 And a lighting device 50 (see FIGS. 3 and 4) for lighting the plurality of lamps 100.

  The housing 13 is, for example, a polyethylene terephthalate (PET) resin material, and a reflective surface is formed by depositing a metal such as aluminum on the inner surface 14 thereof.

  The lamp 100 has a straight tube shape, and 14 lamps 100 having power supply terminals 104 and 105 at both ends thereof are arranged in the casing 13 in a direct manner. The detailed configuration of the lamp 100 will be described later.

  As shown in FIGS. 3 and 4, the lighting device 50 includes a pair of conductive lamp holders 15, 16 disposed on the inner surface on the housing 13 side at positions corresponding to the mounting positions of the lamps 100. For example, it comprises a lighting control circuit 60 (see FIG. 4) that is attached to the outside of the housing 13 and lights each lamp 100 connected to the lamp holders 15 and 16.

  The lamp holders 15 and 16 are electrically conductive and are formed by bending a plate material such as stainless steel or phosphor bronze. Each lamp holder 15 (16) includes sandwiching plates 15a and 15b (16a and 16b) and a connecting piece 15c (16c) that couples the sandwiching plates 15a and 15b (16a and 16b) at the lower edge. The sandwiching plates 15a and 15b and the sandwiching plates 16a and 16b are provided with recesses that match the outer shapes of the power supply terminals 104 and 105 of the lamp 100, and by inserting the power supply terminals 104 and 105 of the lamp 100 into the recesses. The lamps 100 are held by the lamp holders 15 and 16 by the leaf spring action of the clamping plates 15a and 15b and the clamping plates 16a and 16b, and the lamp holders 15 and 16 and the power feeding terminals 104 and 105 are electrically connected. Connected. Note that the width D of the holding portions of the lamp holders 15 and 16 is held within the region of the power supply terminals 104 and 105 provided outside the both ends of the lamp 100 in order to suppress the occurrence of corona discharge when the lamp is lit. The dimensions are designed to be possible.

  Electric power is supplied to each lamp 100 provided in the backlight unit 12 from the lighting control circuit 60 shown in FIG.

  Here, the plurality of lamps 100 are connected and held substantially in parallel by lamp holders 15 and 16 with a predetermined interval therebetween. The lamp holders 15 for connecting and holding one power supply terminal 104 (the power supply terminals 104 such as the lamps La1 and La2 and the lamps La7 and La8 in FIG. 4) in the two adjacent lamps 100 are connected to the ground side. ing. In addition, each of the lamp holders 16 that connect and hold the other power supply terminals 105 (the power supply terminals 105 such as the lamps La1 and La2 and the lamps La7 and La8 in FIG. 4) of the two adjacent lamps 100 are connected to the lighting control circuit 60. Connected to the high voltage side.

  According to this configuration, since one power supply terminal 104 in the two adjacent lamps 100 is connected and held to the ground side by the lamp holder 15, the number of harness processes can be reduced as in the case of the substantially U-shaped cold cathode fluorescent lamp. In addition, since the lamp length is shortened to about half, the luminance unevenness at both ends of the lamp can be reduced. Further, since the lamp 100 can be connected and mounted to the lamp holders 15 and 16 in the casing 13 of the backlight unit 12 with one touch, damage to the sealing portion of the lamp 100 can be prevented, and leads on both outer sides of the lamp 100 can be prevented. The harness processing of connecting the wire 110 and the lead wire 110 from the lighting control device 60 with solder can be reduced. Furthermore, since the straight tubular lamps 100 having the electrodes 102 at both ends are arranged, for example, in the vertical direction, the electrodes 102 serving as a heat source do not concentrate on one side. The difference can be prevented from occurring, and as a result, the luminance unevenness of the backlight unit 12 due to the influence of the mercury vapor pressure of the lamp can be suppressed.

  In general, the circuit configuration is such that the phase difference between the voltages applied to the two adjacent lamp holders 16 is approximately 180 degrees. However, the present invention is not limited to this, and the phase difference between the voltages applied to the two adjacent lamp holders 16 is determined. The circuit configuration may be set to approximately 0 degrees. When the voltage phase difference is set to approximately 0 degrees, the voltage potential difference applied to the two adjacent lamp holders 16 becomes the same potential. The interval between the lamps 100 can be reduced. In the present embodiment, the voltage phase difference is set to approximately 0 degrees, and in order to further reduce the harness processing, for example, a lamp holder 15 that holds and connects one of the power supply terminals 104 in the plurality of lamps La1 to La8. Are all grounded.

  Further, an insulating plate 17 made of polycarbonate that insulates the lamp holders 15, 16 and the housing 13 is disposed between the lamp holders 15, 16 and the housing 13. In the above embodiment, the lamp holder 15 on the ground side is composed of a plurality of parts in which each U-shaped lamp holder 15 is welded to the metal substrate 15d so as to correspond to each lamp. However, the present invention is not limited to this, and it may be configured by one component obtained by cutting and raising each holding plate 15a, 15b from one plate.

  4 shows an example of the lighting control circuit 60 provided in the lighting device 50. FIG. 4A shows the lighting control circuit 60, and FIG. 4B shows each of the lighting control circuits 60 connected to the lighting control circuit 60. It is a figure which shows the connection relation of the lamp | ramp 100. FIG.

For example, the lighting control circuit 60 includes a DC power source (V _DC ), switch elements Q1 and Q2 connected to the DC power source (V _DC ), capacitors C2 and C3, a switch element Q1 and a switch element as shown in FIG. Gates for alternately turning on and off the step-up transformers T1 and T2 (or step-up transformers T7 and T8) and the switch elements Q1 and Q2 connected between the connection point of Q2 and the connection point of the capacitors C2 and C3 It is composed of an inverter control IC that supplies signals.

  On the secondary side of the transformer, as shown in (b), a series resonant circuit is formed by the transformer secondary side leakage inductance, the transformer output, the parasitic capacitance generated in the inner surface 14 of the housing 13 and the lamp, and the lighting The circuit 60 supplies a sinusoidal current having the same phase to two adjacent lamps La1 and La2.

  Returning to FIG. 2, the opening of the housing 13 is sealed with a translucent front panel 21 formed by laminating a diffusion plate 18 made of polycarbonate resin, a diffusion sheet 19, and a lens sheet 20 made of acrylic resin.

  The diffusing plate 18 and the diffusing sheet 19 in the front panel 21 scatter and diffuse the light emitted from the lamp 100, and the lens sheet 20 aligns the light in the normal direction of the sheet 20, Thus, the light emitted from the lamp 100 is configured to irradiate the front uniformly over the entire surface (light emitting surface) of the front panel 21.

  FIG. 5 is a partially broken perspective view showing the cold cathode discharge lamp 100 according to the embodiment of the present invention, and FIG. 6 is an enlarged sectional view showing one end portion of the cold cathode discharge lamp 100.

  The lamp 100 is used as a light source of a backlight unit, and is provided on the outside of a glass bulb 101, a pair of hollow electrodes 102 sealed at both ends of the glass bulb 101, and both ends of the glass bulb 101. Power supply terminals 104 and 105 are provided.

The glass bulb 101 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 101 includes a tubular glass bulb main body 106 and a sealing portion 108 formed using a pair of broken glass beads 107 located on both sides in the longitudinal direction of the glass bulb main body 106. In addition, although the borosilicate glass was used for the material of the glass bulb | bulb 101, 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 101 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 106 has an annular 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. 6, the sealing portion 108 has a maximum width W in the tube axis A direction of the glass bulb 101 of 2 mm, and the hollow electrode 102 is sealed.

  The configuration of the glass bulb 101 is not limited to the above configuration. However, in order to make the lamp 100 elongated, it is desirable that the glass bulb 101 has a small diameter and a thin wall, so that the outer diameter of the glass bulb body 106 is generally 1.8 mm (inner diameter 1.4 mm) to 6. It is preferably 0 mm (inner diameter: 5.0 mm).

A phosphor layer 109 is formed on the inner surface of the glass bulb 101. The phosphor layer 109 is a rare earth composed of, for example, 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 101 is filled with, for example, about 1200 μg of mercury and about 8 kPa (20 ° C.) neon / argon mixed gas (Ne 95% + Ar 5%) as a rare gas.

  Note that the configuration of the phosphor layer 109, mercury, and rare gas is not limited to the above configuration. For example, a neon / krypton mixed gas (Ne 95% + Kr 5%) may be enclosed as a rare gas. When a neon / krypton mixed gas is used as the rare gas, the lamp startability is improved and the lamp 100 can be lit at a low voltage.

  The hollow electrode 102 includes a lead wire 110 fixed to the axis of a cylindrical glass bead 107 (shown by a broken line) and an electrode body 111 welded to one end of the lead wire 110. The glass bulb 101 is hermetically sealed by inserting and sealing the beads 107.

  The electrode body 111 is a nickel (Ni) material and has a bottomed cylindrical shape including a cylindrical portion 112 and a bottom portion 113. The electrode body 111 is not limited to nickel. For example, considering suppression of mercury wear due to electrode sputtering, the electrode body 111 is made of niobium (Nb), tantalum (Ta), or molybdenum (Mo) with less electrode sputtering. It is preferable to use a material.

  The cylindrical portion 112 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 102 is disposed so that the tube axis of the tube portion 112 and the tube shaft of the glass bulb 101 are substantially coincident with each other, and the interval between the outer peripheral surface of the tube portion 112 and the inner surface of the glass bulb 101 is set to the tube portion. It is substantially uniform over the entire outer periphery of 112.

  Specifically, the interval between the outer peripheral surface of the cylindrical portion 112 and the inner surface of the glass bulb 101 is 0.15 mm. As described above, when the interval is narrow, discharge does not enter the interval and discharge occurs only inside the hollow electrode 102. Accordingly, the sputtered material scattered by the discharge is less likely to adhere to the inner surface of the glass bulb 101, and further, the discharge does not flow to the lead wire 110 side, so that the lead wire 110 is not easily heated by the discharge and the lamp 100 has a long life. can do.

  In addition, although the space | interval of the outer peripheral surface of the cylinder part 112 and the inner surface of the glass bulb 101 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 110 is an internal lead wire 114 made of tungsten (W), which is substantially the same material as the thermal expansion coefficient of the glass bulb 101, and is made of nickel that has substantially the same diameter as the internal lead wire 114 and is easily attached to solder or the like. The external lead wire 115 is welded and joined, and a thickened portion 116 larger than the outer diameter of the internal lead wire 114 is formed at the joint portion. The pool portions 116 facing the both end faces of the glass bulb 101 are provided so as to be in close contact with both end portions of the glass bulb 101 (that is, the external lead wire 115 and the pool portion 116 are the outer surfaces of the glass bulb 101). Located outside). With this configuration, the dimensions from the pool portion 116 to the hollow electrode 102 can be made constant. In other words, the gap ε between the bottom of the hollow electrode 102 and the inner surface of the glass bulb 101 facing the effective portion can be reduced to about 0.5 mm. The light emission length L can be increased, and when the projecting portion of the external lead wire 115 collides with the outside, the force applied to the pool portion 116 is absorbed at both ends of the glass bulb 101, so that the internal lead wire 114 It is possible to prevent leakage due to breakage of the sealing portion 108 of the glass bulb 101 to which is sealed.

  The pool portion 116 is formed of the same nickel material as that of the external lead wire 115. However, the present invention is not limited to this.

  The internal lead wire 114 has a substantially circular cross section, a total length of 3 mm, and a wire diameter of 0.8 mm. Further, the internal lead wire 114 is sealed at the end portion of the bulkhead portion 116 side to the sealing portion 108 of the glass bulb 101, and the end portion opposite to the external lead wire 115 side is at the bottom portion 113 of the electrode body 111. It is joined at the approximate center of the outer surface.

  The external lead wire 115 and the pool portion 116 are protruding portions that protrude in the direction of the tube axis A from the outer surface of the glass bulb 101, and are joined to the power supply terminals 104 and 105. The external lead wire 115 and the pool portion 116 have a substantially circular cross section and a total total length σ of 1 mm, and the axis of the external lead wire 115 and the tube axis A of the glass bulb 101 substantially coincide with each other. .

  The total length σ of the external lead wire 115 and the pool portion 116 in the tube axis A direction is preferably 1 mm or less. The outer diameter of the pool portion 116 is preferably 1.5 to 4 times the outer diameter of the internal lead wire 114 in consideration of damage to the sealing portion 108 and part price. As described above, in order to make the lamp 100 elongated, it is preferable that the outer diameter of the glass bulb body 106 is in the range of 1.8 mm to 6.0 mm. If the total total length σ of 115 and the pool portion 116 in the tube axis A direction is 1 mm or less, the external lead wire 115 does not protrude excessively when viewed from the entire lamp 100. Therefore, the external lead wire 115 does not collide with the outside, and the external lead wire 115 is hardly bent or the sealing portion 108 is damaged. For example, when the lamp 100 is attached to the backlight unit 12, the external lead wire 115 may be bent by hitting the backlight unit 12, or the sealing portion 108 may be broken by the stress applied to the external lead wire 115 when hitting the lamp 100. Less is.

  The power supply terminals 104 and 105 are provided at both ends of the glass bulb 101 so as to cover both ends. The power supply terminals 104 and 105 are made of solder, and include a joint portion 117 joined to the external lead wire 115 and the pool portion 116, and a thin film portion 118 as a portion other than the joint portion.

  The joint portion 117 is a portion where the power supply terminals 104 and 105 are electrically connected to the internal lead wire 114, and has a substantially conical shape in appearance. Therefore, the area of the outer surface of the joint portion 117 is small despite completely covering the entire outer surface of the external lead wire 115. Therefore, since the area of the outer surface of the power supply terminals 104 and 105 is small and the heat dissipation action is also small, the temperature of the internal lead wire 114 is unlikely to decrease. In addition, since the external lead wire 115 is completely covered with the power supply terminals 104 and 105, the external lead wire 115 is less likely to be bent or the external lead wire 115 is stressed to damage the sealing portion 108. . Note that the area of the outer surface of the joint portion 117 is preferably as small as possible.

  The thin film portion 118 is formed in a predetermined region on the sealing portion 108 side on the outer surface of the glass bulb main body 106 and a predetermined region on the glass bulb main body 106 side on the outer surface of the sealing portion 108. In order to suppress the heat radiation action of the power supply terminals 104 and 105 to be small, it is preferable that the region where the thin film portion 118 is formed is as narrow as possible.

  The power supply terminals 104 and 105 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 terminals 104 and 105 by the dipping method will be briefly described. For example, the sealing portion 108 of the glass bulb 101 to which the hollow electrode 102 is sealed is immersed in molten solder in the melting tank. When the sealing portion 108 is immersed in the molten solder, ultrasonic waves may be applied. In such a dipping method, the power supply terminals 104 and 105 can be formed easily and inexpensively, so that the lamp 100 can be manufactured at low cost.

  Note that the power supply terminals 104 and 105 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 terminals 104 and 105 is not limited to the above configuration, and for example, a configuration as shown in Modifications 1 to 3 can be considered. 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 100 of 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. 7 is an enlarged cross-sectional view showing one end of the cold cathode fluorescent lamp according to the first modification. A power supply terminal 71 of the cold cathode fluorescent lamp 70 shown in FIG. 7 includes a joining portion 72 and a thin film portion 73. The lead wire 110 is formed, for example, by welding a pooled portion 116 of nickel material to one end of an internal lead wire 114 of tungsten material. The joining portion 72 has a substantially hemispherical shape in appearance and covers the entire outer surface of the pool portion 116 of the lead wire 110.

  According to this configuration, the pool portion 116 is completely covered by the joining portion 72 and the end of the cold cathode fluorescent lamp 70 is smoothly rounded, so that the end of the cold cathode fluorescent lamp 70 is exposed to the outside. Even if it collides, there is little possibility that the sealing part 108 will be damaged.

  Although the lump portion 116 is formed of nickel material, the present invention is not limited to this. For example, after the lump portion 116 is integrally formed of the same material as the internal lead wire 114 of tungsten material, a part or all of the surface of the lump portion 116 is formed. It may be formed by nickel plating which is easy to solder.

  FIG. 8 is an enlarged cross-sectional view showing one end of a cold cathode fluorescent lamp according to Modification 2. A power supply terminal 81 of the cold cathode fluorescent lamp 80 shown in FIG. 8 includes a joining portion 82 and a thin film portion 83. The lead wire 110 is formed, for example, by welding a pooled portion 116 of nickel material to one end of an internal lead wire 114 of tungsten material. Further, the pool portion 116 is embedded in the end portion of the glass bulb 101. The joint portion 82 covers the outer surface of the pool portion 116 of the lead wire 110 with a thin film. The thickness of the thin film is 10 μm, which is the same as that of the thin film portion 83.

  According to this configuration, since the pool portion 116 is embedded in the end portion of the glass bulb 101, the pool portion 116 does not hit the outside, and the sealing portion 108 can be prevented from being damaged. Further, by using the entire power supply terminals 81 and 82 as a thin film, the amount of solder used can be reduced, and the cold cathode fluorescent lamp 80 can be manufactured at a lower cost.

  In particular, when the power supply terminals 104 and 105 are entirely formed of solder, the power supply terminals 104 and 105 are easily formed by the dip method. Therefore, the cold cathode fluorescent lamp 100 can be manufactured more easily and at a lower cost than a conventional power supply terminal that requires assembly of components. In addition, since the solder generally has lower thermal conductivity than the iron / nickel alloy used for the cap-shaped power supply terminals 104 and 105, the heat radiation action of the power supply terminals 104 and 105 can be further reduced. For this reason, the lamp brightness is less likely to decrease.

  In the second modification, the whole pool portion 116 is completely buried in the end portion of the glass bulb 101. However, the present invention is not limited to this, and a part of the pool portion 116 may be buried. That is, the greater the amount of the buried portion 116 embedded in the end portion of the glass bulb 101, the lower the probability of colliding with the outside.

  FIG. 9 is an enlarged cross-sectional view showing one end portion of a cold cathode fluorescent lamp according to Modification 3, and FIG. 10 is a perspective view showing a thin film member constituting a power supply terminal. The power supply terminal 91 of the cold cathode fluorescent lamp 90 shown in FIG. 9 includes a solder joint portion 92 and a thin film member 93 made of iron / nickel alloy as a thin film portion. As described above, the power supply terminal 91 does not necessarily have to be entirely made of the same material.

  As shown in FIG. 10, the thin film member 93 is a tantalum cylinder having a thickness of 120 μm and having a substantially C-shaped cross section, and is fitted on the end of the glass bulb 101. The inner diameter of the thin film member 93 is slightly smaller than the outer diameter of the glass bulb 101, and the thin film member 93 is provided with a slit 94. Therefore, even if a slight dimensional error occurs between the inner diameter of the thin film member 93 and the outer diameter of the glass bulb 101, the inner surface of the thin film member 93 is designed to be in close contact with the outer surface of the glass bulb 101.

  Note that the thin film member 93 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 115 and the bulge portion 116 is 1 mm, and the length L1 of the thin film member 93 in the portion containing the external lead wire 115 and the bulge portion 116 is 1.5 mm. The joint portion 92 is a thick region (region L1) of the external lead wire 115 and the pool portion 116.

  When the power supply terminal 91 is configured as described above, since the external lead wire 115 does not protrude to the outside, no stress is applied to the sealing portion 108 of the glass bulb 101 even if the power supply terminal 91 is struck outside. Is hard to break.

  Note that a material for forming the power supply terminals 104, 105, 71, and 81 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 dissipation action of the power supply terminals 104, 105, 71, and 81 does not increase.

  In general, solder is suitable as a material for the power supply terminals 104, 105, 71, and 81 because it has good conductivity, low thermal conductivity, and low price. In particular, a solder mainly composed of tin (Sn), tin-indium (In) alloy, tin-bismuth (Bi) alloy, or the like may form the power supply terminals 104, 105, 71, 81 having high mechanical strength. Since it is possible, it is more preferable. 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 104, 105, 71, 81 that are difficult to peel off from the glass bulb 101, which is more preferable. In addition, lead-free solder is suitable because it can produce a cold cathode fluorescent lamp in consideration of the environment.

  The cold cathode fluorescent lamp is operated at a lighting frequency of 30 to 120 kHz and a lamp current of 3.0 to 8.5 mA.

(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. 11 shows the temperature characteristics of the cold cathode fluorescent lamp.

  11, the cold cathode fluorescent lamp of the example is the same as the cold cathode fluorescent lamp 100 according to the present embodiment shown in FIGS. 5 and 6 except that the film thickness of the thin film portion of the power supply terminal is 50 μm. It has a configuration.

  As shown in FIG. 15, the cold cathode fluorescent lamp of Comparative Example 1 is a conventional cold cathode fluorescent lamp that does not include a power supply terminal, and the cold cathode fluorescent lamp according to the present embodiment except for the structure related to the electrode and the power supply terminal. It has almost the same configuration as the lamp.

  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.

  As shown in FIG. 11, 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 electrodes. 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. 12 is a diagram illustrating the relationship between the film thickness of the thin film portion of the power supply terminal and the temperature near the electrode. As shown in FIG. 12, when the film thickness of the thin film portion of the power supply terminal is 120 μm, there is no temperature difference between the vicinity of the glass bulb electrode and the central portion of the glass bulb. Therefore, the film thickness of the thin film portion is preferably 120 μm or less so that the temperature in the vicinity of the electrode 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.

  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.

  The cold cathode fluorescent lamp is not limited to a circular cross section, and may be a flat cold cathode fluorescent lamp having an elliptical shape or a long circular hole shape. For example, as shown in FIG. 13, a light extraction portion (a hollow disposed in the above-mentioned position from both ends of the glass bulb 201) in a positive column light emitting portion of the glass bulb 201 (substantially in a region where the positive column is generated). The cross section of the flat portion in the region between the tips of each of the electrodes 202 and 203 is flat, the cross section of at least the hollow electrodes 202 and 203 of the glass bulb 201 is circular, and the flat shape of the glass bulb 201 is flat. The length Da of the light extraction portion in the tube axis X direction is longer than the circular lengths Db and Dc in the tube axis X direction of the regions of the hollow electrodes 202 and 203.

Here, each dimension of the lamp 200 will be described. The total length L of the lamp 200 is 705 mm, the length Da of the positive column light emitting part is about 680 mm, the circular lengths Db and Dc on the electrode part side are about 12 mm, respectively, and the outer peripheral surface area of the positive column light emitting part is about 105 cm ² . . Further, the short outer diameter ao of the substantially elliptical shape is 4.0 mm, the short inner diameter ai is 3.0 mm, the long outer diameter bo is 5.8 mm, and the long inner diameter bi is 4.8 mm. The substantially circular tube outer diameter ro is 5.0 mm, and the tube inner diameter ri is 4.0 mm.

  According to this configuration, since the cross section of the light extraction portion of the glass bulb 201 has a flat shape, it is possible to suppress an excessive increase in the coldest spot temperature by increasing the outer surface area than the conventional straight tube lamp, Moreover, the short inner diameter ai having a flat shape is shorter than a conventional straight tube lamp having a tube inner diameter comparable to the long inner diameter bi, so that the distance from the center of the positive column plasma space to the inner wall of the tube is effectively kept short. It becomes possible. For this reason, even if the lamp current is increased as compared with the prior art, it is possible to make it difficult to reduce the light emission efficiency.

  In addition, the power supply terminal is not limited to the configuration of the embodiment shown in FIGS. 6 to 9, and for example, as shown in FIG. 13, the main component is silver or copper formed on the outer surface of the glass bulb 201. The main body layers 204 and 205 and the main layer laminated on the outside thereof may be composed of coating layers 206 and 207 made of solder. According to this configuration, the main body layers 204 and 205 of the power feeding terminal are not easily exposed to the atmosphere, and silver sulfide and copper oxidation are unlikely to occur. As a result, it is possible to improve the connectivity between the power supply terminal and the lead wire of the electrode, and to prevent the power supply terminal from being scratched or cracked when the cold cathode fluorescent lamp is attached to the lamp holder.

  In this embodiment, the maximum thickness of the power supply terminal is 5 to 120 μm, and the thicknesses of the edge portions 206a and 207a of the power supply terminal are made thinner as they approach the edge. As a result, the corona discharge generated between the edge of the power supply terminal and the outer surface of the glass bulb 201 can be prevented, and the generation of ozone can be suppressed, compared to the case where the edge of the power supply terminal is square. . If the film thickness of the power supply terminal is thinner than 5 μm, the thin films of the main body layers 204 and 205 are easily peeled off from the glass bulb and cannot be used in actual use. On the other hand, if the film thickness of the power supply terminal is thicker 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. It tends to be lower than the lamp. Therefore, there is a possibility that sufficient lamp brightness cannot be obtained.

  Instead of the coating layers 206 and 207, as shown in FIG. 14, cap-shaped metal members 306 and 307 that surround and connect at least part of the outer peripheral surfaces of the main body layers 204 and 205 may be used. The metal member 306 is the same as the metal member 307. The metal member 307 is made of a material made of, for example, Fe-Ni-Co (Kovar), which has good electrical conductivity and a thermal expansion coefficient close to that of the glass bulb 201. In order to give the metal member 307 an elastic force, for example, two slits 309 are provided in the longitudinal direction. The metal member 307 is mounted from the end 201 b of the glass bulb 201 and is connected to the main body layer 205 by the elastic force of the slit 309. In this embodiment, the structure of the end portion of the power supply terminal is such that, for example, the end portions 306a and 307a of the metal members 306 and 307 on the center side of the glass bulb 201 are the end portions 204a of the main body layers 204 and 205 on the center side of the glass bulb. , 205a from the position of the glass bulb end 201b to the glass bulb end 201b side. According to this structure, it can suppress that the corona discharge at the time of lamp lighting generate | occur | produces between the metal members 306 and 307 and the glass bulb | bulb 201, and can reduce the generation amount of ozone. The shape of the metal members 306 and 307 is not limited to the cap shape, and may be a sleeve shape.

  Further, any of the embodiments shown in FIGS. 6 to 9, 13 and 14 may be combined.

  The lighting device and the backlight unit according to the present invention reduce the luminance unevenness in the lamp length direction (both left and right sides in the envelope) in addition to reducing the harness processing in the same manner as the substantially U-shaped cold cathode fluorescent lamp. In addition, it has the effect of preventing the cold cathode fluorescent lamp from being damaged in the sealing portion and the like, and connecting and mounting the cold cathode fluorescent lamp in the unit housing with one touch, and is useful as an illumination device, a liquid crystal television, a liquid crystal display, and the like.

The perspective view which shows the outline | summary of the liquid crystal television in Embodiment 1 of this invention The perspective view which shows the backlight unit which concerns on Embodiment 1 of this invention. The perspective view which shows the lighting device which concerns on Embodiment 1 of this invention. An example of the lighting control circuit with which the lighting device which concerns on Embodiment 1 of this invention is provided is shown, (a) is a figure which shows a lighting control circuit, (b) is the connection of each cold cathode fluorescent lamp connected to the lighting control circuit Diagram showing relationship The partially broken perspective view which shows the cold cathode discharge lamp which concerns on 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 (A) is sectional drawing which shows the cold cathode fluorescent lamp concerning the application example 1, (b) is sectional drawing shown by the BB line in (a), (c) is sectional drawing shown by the CC line, d) is a sectional view taken along line D-D. (A) is sectional drawing which shows the cold cathode fluorescent lamp concerning the application example 2, (b) is a figure which shows the external appearance of the metal member 307, (c) is sectional drawing shown by the BB line in (a), (d ) Is a cross-sectional view taken along the line CC, and (e) is a cross-sectional view taken along the line DD. Sectional drawing which shows the edge part of the conventional cold cathode fluorescent lamp provided with the hollow electrode

Explanation of symbols

12 Backlight unit 15, 16 Lamp holder 50 Lighting device
60 lighting control circuit 100 cold cathode fluorescent lamp 101 glass bulb 102 hollow electrode 104, 105 power supply terminal 110 lead wire

Claims (20)

A cold cathode fluorescent lamp provided with a pair of electrodes sealed at both ends of a straight glass bulb and the outside of both ends of the glass bulb, and having a power supply terminal joined to a lead wire of the electrode; A lighting device comprising a conductive lamp holder provided on a housing side so that power supply terminals at both ends of a glass bulb are connected, and a lighting circuit connected to the lamp holder and lighting the cold cathode fluorescent lamp. And at least one of the lamp holders connected to the power supply terminals of the two adjacent cold cathode fluorescent lamps is connected to the ground side, and the other of the lamp holders is connected to the high voltage side of the lighting circuit. A lighting device characterized by that. 2. The lighting device according to claim 1, wherein a phase difference between voltages applied to two adjacent lamp holders connected to a high voltage side of the lighting circuit is approximately 0 degrees. The lighting device according to claim 1, wherein the electrode of the cold cathode fluorescent lamp is a cylindrical hollow electrode. The cold cathode fluorescent lamp has a flat cross section of a light extraction portion in a positive column light emitting portion of the glass bulb, a circular cross section of at least the hollow electrode region of the glass bulb, and the glass bulb The lighting device according to claim 3, wherein a length of the flat light extraction portion is longer than a circular length in a region of the hollow electrode. The lighting device according to any one of claims 1 to 4, wherein the power supply terminal is a thin film formed on an outer surface of the glass bulb except for a joint portion with the lead wire. The lighting device according to claim 5, wherein the thin film has a thickness of 5 to 120 μm. The lighting device according to claim 5 or 6, wherein at least the joint portion of the thin film is formed of solder. The power supply terminal is formed of a main body layer mainly composed of silver or copper formed on the outer surface of the glass bulb, and a coating layer or a thin metal member laminated outside the main body layer. The lighting device according to claim 1, wherein: The feeding terminal has an end portion of the coating layer or thin metal member on the glass bulb center side spaced from the position of the main body layer end portion on the glass bulb center side to the glass bulb end side. The lighting device according to claim 8, wherein the lighting device is installed. 10. The lighting device according to claim 8, wherein the power supply terminal has a thickness of 5 to 120 μm between the main body layer and a coating layer laminated outside the main body layer. 11. The lighting device according to claim 8, wherein the coating layer is mainly composed of solder. The lighting device according to any one of claims 5 to 11, wherein the thickness of the edge portion of the power supply terminal is reduced as the thickness approaches the edge. The lighting device according to claim 12, wherein an end edge portion of the power supply terminal has an arc shape on the outer side, and the thickness thereof decreases as the end edge is approached. 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 is the glass bulb. The lighting device according to claim 1, wherein the lighting device is in close contact with both ends. The lead wire is made of a material whose sealing portion with the glass bulb is 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 made of nickel material or nickel plating. The lighting device according to claim 14, wherein the lighting device is formed. The lighting device according to claim 14 or 15, wherein the pool portion of the lead wire is embedded in an end portion of the glass bulb. The lighting device according to any one of claims 14 to 16, 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. . 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 lighting device according to claim 1, wherein the lighting device is a lighting device. It is a backlight unit used for a liquid crystal display, Comprising: The lighting device of any one of Claims 1-18 is provided, The backlight unit characterized by the above-mentioned. 20. A liquid crystal television comprising a direct type backlight unit, wherein the backlight unit is the backlight unit according to claim 19.

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