JP2007207524A - Fluorescent lamp, manufacturing method thereof, light emitting device using the fluorescent lamp, and display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fluorescent lamp achieving both of suppression of mercury consumption and high brightness, and a method of manufacturing the same, and to provide a light emitting device using the fluorescent lamp, and a display device. <P>SOLUTION: The fluorescent lamp of the present invention includes a translucent container, mercury enclosed in the translucent container, and a phosphor layer formed on an inner surface of the translucent container. The phosphor layer includes phosphor particles 2a, and a rod-shaped body 2b forming cross-links between the phosphor particles and containing a metal oxide. The rod-shaped body 2b has a thickness of 1.5 μm or smaller, for example. A pair of adjacent phosphor particles may be cross-linked by a plurality of rod-shaped bodies. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fluorescent lamp, a manufacturing method thereof, and a light emitting device and a display device using the fluorescent lamp. The present invention particularly discloses the structure of the phosphor layer.

  In general, in a fluorescent lamp such as a cathode fluorescent lamp, a phosphor layer containing a phosphor is formed on the inner surface of a translucent container made of a glass tube or the like. The glass tube is filled with an ionizable gas containing mercury and one or more rare gases. In the glass tube, electrodes are arranged in the vicinity of both ends of the glass tube. When positive column discharge is started between the electrodes, mercury in the glass tube is excited and ionized, and resonance lines (wavelengths of 185 nm, 254 nm, 313 nm, and 365 nm) are generated with the excitation of mercury. This resonance line is converted into visible light by the phosphor layer formed on the inner surface of the glass tube.

  In recent years, from the viewpoint of environmental protection, there is an increasing demand for reducing the amount of mercury used in fluorescent lamps. For this reason, development of a technique for suppressing the mercury consumption in the glass tube is required. However, it is known that mercury in the fluorescent lamp is gradually consumed over the time of use due to the following phenomenon. When the fluorescent lamp is turned on, mercury is consumed by diffusing into the glass tube, reacting with sodium (Na) diffused from the glass tube to the phosphor to form amalgam, or adsorbed on the phosphor. Consumed mercury easily absorbs visible light and becomes one of the causes of a decrease in luminance.

FIG. 11 shows a partial cross section of a phosphor layer of a conventional fluorescent lamp that solves the problem of mercury consumption (see, for example, Patent Document 1 and Patent Document 2). As shown in FIG. 11, the phosphor layer 100 is formed by depositing phosphor particles 120 on a glass tube 130, and a part of the surface of the phosphor particles 120 is covered with a metal oxide 110. Yes. The metal oxide 110 is arranged between the adjacent phosphor particles and connected to each other, thereby narrowing the gap between the phosphor particles. The presence of the metal oxide 110 reduces mercury entering the phosphor layer 100 and suppresses mercury consumption due to adsorption to the phosphor.
International Publication No. WO2002 / 047112 Pamphlet JP 2004-6399 A

  However, since the metal oxide 110 is in a lump shape, the light converted by the phosphor layer is difficult to transmit outside the glass tube 130. Therefore, the conventional fluorescent lamp has a problem that the initial luminance is lowered while mercury consumption can be suppressed.

  The present invention provides a fluorescent lamp, a method for manufacturing the same, and a light-emitting device and a display device using the fluorescent lamp, in which both mercury consumption suppression and high luminance are achieved.

  The fluorescent lamp of the present invention includes a translucent container, mercury sealed in the translucent container, and a phosphor layer formed on the inner surface of the translucent container, and the phosphor layer includes: It comprises phosphor particles and a rod-like body that contains a metal oxide and crosslinks the phosphor particles.

  The method for producing a fluorescent lamp of the present invention includes applying a coating material in which phosphor particles are dispersed in a solvent and dissolving a metal compound in the solvent to the inner surface of the translucent container, and the coating material is included in the applied coating material. A phosphor layer forming step in which after the solvent is vaporized, the paint is heated to form a phosphor layer in which the metal compound is a metal oxide and the phosphor particles are cross-linked by a rod-shaped body containing the metal oxide; And a mercury sealing step of sealing mercury in the translucent container after forming the phosphor layer, wherein the solvent includes two or more solvents having different boiling points.

  The light emitting device of the present invention includes a plurality of fluorescent lamps, and an envelope having a window portion in which the plurality of fluorescent lamps are housed and capable of transmitting light emitted from the plurality of fluorescent lamps. The fluorescent lamp is the fluorescent lamp of the present invention.

  The display device of the present invention includes a display panel and the light emitting device of the present invention disposed on the back surface of the display panel.

  According to the present invention, since the phosphor particles contained in the phosphor layer are cross-linked by the rod-like body containing the metal oxide, the light converted by the phosphor layer is easily transmitted to the outside of the glass tube. Intrusion of mercury into the phosphor layer can be suppressed by the rod-shaped metal oxide, and consumption of mercury due to adsorption to the phosphor can be suppressed. Therefore, according to the present invention, it is possible to provide a fluorescent lamp, a manufacturing method thereof, and a light-emitting device and a display device using the fluorescent lamp, in which both consumption of mercury and high luminance are compatible.

  Hereinafter, preferred embodiments of the present invention will be described.

  In an example of the fluorescent lamp of the present invention, the thickness of the rod-shaped body whose length in the direction between the phosphor particles is longer than the length in the radial direction is 1.5 μm or less. In addition, a pair of adjacent phosphor particles may be cross-linked by a plurality of rod-shaped bodies. Here, the “thickness” of the rod-shaped body is the length in the longitudinal direction of the rod-shaped body (the length in the direction between the phosphor particles cross-linked by the rod-shaped body), which is seen when observed with a high resolution scanning microscope (HRSEM). It means the thickness at a half point.

Specifically, the metal oxide preferably contains at least one selected from Y, La, Hf, Mg, Si, Al, P, B, V, and Zr. A particularly preferred metal is Y. When the metal oxide contains, for example, Y ₂ O ₃ as an oxide of Y, mercury consumption is further reduced.

  In an example of the fluorescent lamp of the present invention, the translucent container is tubular glass, and its inner diameter is as small as 1.2 mm to 13.4 mm. For such a fluorescent lamp having a small inner diameter, it is very beneficial to employ a phosphor layer including phosphor particles cross-linked by a rod-shaped body made of a metal oxide.

  In an example of the manufacturing method of the fluorescent lamp of the present invention, it is preferable to use an organic metal compound such as yttrium carboxylate as the metal compound. In this case, it is preferable to vaporize the solvent in the phosphor layer forming step while supplying a gas having a humidity (relative humidity) of 10% to 40% at 25 ° C. into the translucent container. If the humidity in the translucent container is too low, the reason is not clear, but the uniformity such as the thickness of the phosphor layer deteriorates, and if it is too high, the vaporization of the solvent takes too much time and the production efficiency deteriorates. . If the vaporization of the solvent is performed while supplying a gas having a humidity of 10% to 40% at 25 ° C. in the translucent container, a phosphor layer with excellent uniformity can be efficiently formed. Although the atmospheric temperature at the time of vaporizing a solvent changes with kinds of solvent contained in a coating material, 25 to 50 degreeC is suitable normally.

  An example of the fluorescent lamp of the present invention is preferably used as a light source constituting a light emitting device, for example. An example of the light-emitting device includes, for example, a plurality of examples of the fluorescent lamp of the present invention, and these are housed in an envelope having a window portion that can transmit light emitted from the fluorescent lamp.

  An example of the light emitting device is preferably used as a backlight unit constituting a display device such as a liquid crystal display device. In an example of the liquid crystal display device, for example, the light emitting device is disposed on the back surface of the display panel.

  Hereinafter, an example of the present invention will be described with reference to the drawings.

(Embodiment 1)
In Embodiment 1, an example of the fluorescent lamp of the present invention will be described. FIG. 1 is a cross-sectional view showing an example of the fluorescent lamp of the present embodiment, and FIG. 2 is an enlarged conceptual diagram of a phosphor layer constituting the fluorescent lamp shown in FIG.

  The fluorescent lamp shown in FIG. 1 is a cold cathode fluorescent lamp 1. In the fluorescent lamp 1, both end portions of the glass tube 4 having a circular cross section are hermetically sealed by lead wires 3, and electrodes 6 are respectively provided at end portions of the lead wire 3 in the glass tube 4. It is joined. A phosphor layer 2 is formed in a predetermined region on the inner surface of the glass tube 4.

  As shown in FIG. 2, the phosphor layer 2 includes phosphor particles 2a, and the phosphor particles are cross-linked with each other by a rod-shaped body 2b containing a metal oxide. The thickness of the rod-shaped body 2b is, for example, 1.5 μm or less. A pair of adjacent phosphor particles 2a may be cross-linked by a plurality of rod-like bodies 2b. Due to the presence of the rod-shaped body 2b, the gap between the phosphor particles 2a is narrowed, and the intrusion of mercury into the phosphor layer 2 is suppressed. Therefore, the consumption of mercury by adsorbing to the phosphor particles 2a is suppressed. Moreover, since the metal oxide which is arrange | positioned between the fluorescent substance particles 2a and bridge | crosslinks the fluorescent substance particles 2a is rod-shaped, the light converted by the fluorescent substance layer 2 is easy to permeate | transmit the outer side of the glass tube 4. FIG. From the above, the fluorescent lamp 1 according to the present embodiment achieves both suppression of mercury consumption and high luminance, as will be described later in Examples.

Specifically, the metal oxide preferably contains at least one selected from, for example, Y, La, Hf, Mg, Si, Al, P, B, V, and Zr. Of these, Zr, Y, Hf and the like are preferable because the bond energy with the oxygen atom exceeds 10.7 × 10 ⁻⁹ J. 10.7 × 10 ⁻⁹ J corresponds to the photon energy possessed by the ultraviolet ray having a wavelength of 185 nm among the resonance lines generated with the excitation of mercury. When a metal oxide containing a metal having a binding energy with an oxygen atom exceeding 10.7 × 10 ⁻⁹ J, for example, ZrO ₂ , Y ₂ O ₃ , HfO ₂ is used, the metal oxide with respect to irradiation with ultraviolet rays having a wavelength of 185 nm Improves durability. Further, it is preferable that the metal oxide contains Y ₂ O _{3 because} mercury consumption is further reduced.

For example, SiO ₂ , Ai ₂ O ₃ , or HfO ₂ may be used as the metal oxide. These have a high transmittance of about 100% for light having a wavelength of 254 nm. The phosphor emits light upon receiving light at 254 nm. Therefore, it is preferable to use a metal oxide having a high light transmittance at a wavelength of 254 nm because the light emission efficiency is increased.

The transmittance of light having a wavelength of 254 nm is about 95% for ZrO ₂ and about 85% for V ₂ O ₅ , Y ₂ O ₃ , and NbO ₅ . The Y ₂ O _3, ZrO _2, less transmittance of light is low wavelength 200 nm, respectively, less than 30%, less than 20%. For this reason, these are preferable because they have a large blocking effect on light having a wavelength of 185 nm, which degrades the phosphor.

  For example, the phosphor layer is formed on the inner surface of the glass tube 4 while leaving the inner surfaces of both ends of the glass tube 4. Although there is no restriction | limiting in particular about the distance M from the end surface of the glass tube 4 to a fluorescent substance layer, For example, 4 mm-7 mm are suitable.

The composition of the phosphor contained in the phosphor layer 2 is not particularly limited as long as it includes a phosphor that emits red light, a phosphor that emits green light, and a phosphor that emits blue light. For example, (Y ₂ O ₃ : Eu), (YVO ₄ : Eu), etc. are used for phosphors that emit red light, and (LaPO ₄ : Ce, Tb), (for example) are used for phosphors that emit green light. Examples of phosphors that emit blue light such as BaMg ₂ Al ₁₆ O ₂₇ : Eu, Mn) include (BaMg ₂ Al ₁₆ O ₂₇ : Eu), (Sr, Ca, Ba) ₅ (PO ₄ ) ₃ Cl. : Eu or the like is used. The blending ratio of these phosphors may be adjusted so that the color temperature is, for example, 3000K or higher.

  The phosphor layer 2 may contain a thickener, a binder or the like as necessary in addition to the phosphor particles and the metal oxide.

  The material of the glass tube 4 may be, for example, hard borosilicate glass having the following composition other than soda glass.

SiO ₂ 68-77%
Al ₂ O ₃ 1-6%
B ₂ O ₃ 14-18%
Li ₂ O 0-0.6%
Na ₂ O 1-5%
K ₂ O 1-6%
MgO 0.3-0.6%
CaO 0.6-1%
SrO 0-0.05%
BaO 0 to 1.3%
Sb ₂ O ₃ 0-0.7%
As ₂ O ₃ 0-0.2%
TiO ₂ 0.4-6%
ZrO ₂ 0-0.2%

  Although there is no restriction | limiting in particular about the dimension of a glass tube, 39 mm-1300 mm are suitable for the tube length L, for example. When the glass tube is made of borosilicate glass, the inner diameter is preferably 1.2 mm to 3.8 mm and the outer diameter is preferably 1.8 mm to 4.8 mm in consideration of cost and the like. When the glass tube is made of soda glass, the inner diameter is preferably 3.0 mm to 13.4 mm and the outer diameter is preferably 4.0 mm to 15.0 mm in view of mechanical strength and the like. In this way, the fluorescent lamp 1 using the glass tube 4 having a small inner diameter has a higher lamp current density than the fluorescent lamp using the glass tube having a larger inner diameter. Such reduction in diameter and increase in current increase the radiation rate of ultraviolet light having a wavelength of 185 nm among the resonance lines generated with the excitation of mercury. In particular, since the short-wavelength resonance line deteriorates the phosphor, an increase in the emission ratio of the short-wavelength resonance line increases the luminance reduction rate with the lighting time. In addition, the mercury consumption rate is increased and the luminance reduction rate is increased. For this reason, the use of a phosphor layer having a structure in which phosphor particles are cross-linked by a rod-like metal oxide is very beneficial for a fluorescent lamp 4 having a small inner diameter of, for example, 1.2 mm to 13.4 mm. is there.

  In the glass tube 4, for example, an appropriate amount of mercury (not shown) and one or more rare gases are sealed. An appropriate amount of mercury enclosed is, for example, 1 mg to 4.8 mg. As the rare gas, for example, argon (Ar) gas, neon (Ne) gas or the like is used. The mixing ratio of these gases is suitably, for example, 5 to 10% by volume of Ar gas with respect to 90 to 95% by volume of Ne gas. An appropriate gas pressure in a state where the fluorescent lamp 1 is not lit is, for example, 6.3 to 20 kPa.

  The lead wire 3 includes, for example, an internal lead wire 3 a disposed in the glass tube 4 and an external lead wire 3 b that is joined to the internal lead wire 3 a and disposed outside the glass tube 4. The internal lead wire 3a is made of tungsten, for example, and the external lead wire 3b is made of nickel, for example.

The electrode 6 has, for example, a bottomed cylindrical shape, and is also called a hollow electrode. The electrode 6 is joined to the lead wire 3 by a method such as laser welding. The electrode 6 has a structure in which an emitter (not shown) is held on the inner surface of a bottomed cylindrical body. The bottomed cylindrical material is made of, for example, Nb or Ni, and the emitter is made of, for example, Cs ₂ AlO ₃ or the like.

  The size of the electrode 6 is set so that the effective surface area contributing to discharge becomes a desired size. For example, the axial length N of the electrode 6 is 3.1 mm to 5.6 mm, and the inner diameter is 1 mm to 2 mm. .8 mm. The distance R from the end face of the glass tube 4 to the electrode 6 is suitably 5 mm to 8.3 mm, for example.

As shown in FIG. 3, it is preferable that the phosphor particles 2 a are not exposed on the surface opposite to the surface facing the glass tube 4 of the phosphor layer 2. That is, the phosphor particles 2a are embedded in the phosphor layer 2 so that the surface of the phosphor particles 2a does not form part of the opposite surface, and the opposite surface is made of metal oxide or the like. Preferably it is formed. In this case, the phosphor particles 2a are isolated from mercury, and the adsorption of mercury to the phosphor particles 2a is more effectively suppressed. If a metal oxide having a high transmittance with respect to light with a wavelength of 245 nm, for example, 85% or more is used as the metal oxide, the wavelength of 245 nm reaches the phosphor particles 2a, and the phosphor particles can emit light. In this case, the metal oxide, for example, preferably a _{SiO 2, Ai 2 O 3,} HfO 2, ZrO 2, V 2 O 5, Y 2 O 3, NbO 5 , and the like.

As shown in FIG. 3, a continuous metal oxide layer 5 may be formed between the glass tube 4 and the phosphor layer 2. Also in this case, the glass tube 4 is isolated from mercury, and it is possible to suppress the mercury from being diffused into the glass tube 4 and consumed. When the glass tube 4 is made of, for example, soda glass containing a large amount of Na, it is possible to suppress the formation of amalgam due to the reaction of Na and mercury. As the metal oxide constituting the metal oxide layer 5, for example, at least one selected from Y, La, Hf, Mg, Si, Al, P, B, V and Zr is used. The metal oxide constituting the metal oxide layer 5 may be the same as or different from the metal oxide contained in the phosphor layer 2, and among them, SiO ₂ , Al ₂ O ₃ etc. are particularly preferable.

  The fluorescent lamp of the present embodiment has been described by taking the cold cathode fluorescent lamp as an example. However, the present invention is not limited to this, and for example, an external electrode fluorescent lamp, a hot cathode fluorescent lamp, and a bulb fluorescent lamp The present invention can be similarly applied to an electrodeless fluorescent lamp using a lamp, an external dielectric coil, or the like.

(Embodiment 2)
In the second embodiment, an example of a method for manufacturing the fluorescent lamp described in the first embodiment will be described.

  As shown in FIG. 4, first, the coating material for forming the phosphor layer 2 is adjusted. The coating material is prepared by dispersing a predetermined amount of phosphor particles in a solvent, and adding a predetermined amount of a metal compound to the obtained suspension to dissolve it. The solvent used here contains two or more organic solvents having different boiling points. Specifically, boiling points differ from butyl acetate (boiling point 120-126.5 ° C), ethanol (boiling point 78.3 ° C), methanol (boiling point 64.6 ° C), turpentine oil (boiling point 150-200 ° C), etc. Two or more kinds of solvents may be appropriately selected.

  Regarding the blending ratio of two or more solvents, the high boiling point solvent is suitably 0.1 wt% to 10 wt% and more preferably 2 wt% to 6 wt% with respect to 100 wt% of the low boiling point solvent. . By adjusting the blending ratio of the low boiling point solvent and the high boiling point solvent, the average thickness of the rod-shaped body can be adjusted to a desired value.

  Although there is no restriction | limiting in particular about the addition amount of a metal compound, For example, the metal oxide obtained by reaction of a metal compound is about 0.1-0.6 weight part to a fluorescent substance layer with respect to 100 weight part of fluorescent substance particles. It is preferred that a metal compound be added so as to be included. If the metal oxide obtained by the reaction of the metal compound is too small, the phosphor layer has insufficient strength, and if it is too large, the luminance is insufficient. If the metal compound is added so that the metal oxide is contained in an amount of about 0.1 to 0.6 parts by weight with respect to 100 parts by weight of the phosphor particles, a phosphor layer having both strength and brightness can be obtained. Can do. Although there is no restriction | limiting in particular also about the addition amount of a solvent, For example, about 45-120 weight part is suitable with respect to 100 weight part of fluorescent substance particles.

  The coating material may contain a binder, a thickener, etc. as needed. As the binder, for example, a phosphorus-based binder or a boron-based binder is used, and as the thickener, etc., nitrocellulose is used. In this case, the addition amount of the binder is suitably about 0.1 to 2 parts by weight with respect to 100 parts by weight of the phosphor particles, and the addition amount of the thickener is, for example, 100 parts by weight of the phosphor particles. About 0.3 to 2.5 parts by weight per part is appropriate.

Next, a paint is applied to the inner surface of the glass tube 4. Application of the coating material to the glass tube 4 is performed, for example, by a method of sucking up the liquid from above the upright glass tube 4. Although there is no restriction | limiting in particular about the application quantity of a coating material, It adjusts so that 2-5 mg / cm < ² > of fluorescent substance may be contained in a fluorescent substance layer.

  Next, the organic solvent contained in the applied paint is vaporized, and the paint layer is dried. At this time, as the solvent in the paint is vaporized, the concentration of the metal compound in the paint increases (the metal compound solution is concentrated), and the metal compound is eventually deposited between the phosphor particles. As the vaporization progresses, the solution moves to a narrower gap between the phosphor particles due to the surface tension. As a result, the metal compound precipitates in a portion where the interval between the phosphor particles is narrow.

  The paint is dried, for example, in a state where the glass tube 4 is upright, that is, without changing the posture of the glass tube 4 after application of the paint. Or you may carry out rotating an upright glass tube.

The paint may be dried by keeping the inside of the glass tube 4 in an atmosphere in which the solvent is easily vaporized. For example, gas may be continuously supplied into the glass tube 4. Although there is no restriction | limiting in particular about the supply_amount | feed_rate of gas, if there are too few supply amounts, productivity will worsen, and when there are too many supply amounts, formation of a highly uniform fluorescent substance layer will be inhibited. Therefore, the gas supply amount is suitably over 0 and 64 ml / min / cm ² , more preferably 16 to 48 ml / min / cm ² . The solvent does not need to be completely removed and may remain slightly.

  The coating is preferably dried while supplying a gas having a humidity of 10% to 40% at 25 ° C. into the glass tube 4 as shown in Example 2 described later. If the humidity in the glass tube 4 is too low, the reason is not clear, but the uniformity such as the thickness of the phosphor layer 2 is deteriorated. Specifically, voids are generated in the phosphor layer 2 as if the paint had fallen off during drying, thereby causing irregularities in the phosphor layer 2. On the other hand, if the humidity is too high, it takes time to evaporate the solvent, and the production efficiency deteriorates. If vaporization of the solvent is performed while supplying the gas into the glass tube 4, the phosphor layer 2 having excellent uniformity such as thickness can be efficiently formed. Further, by improving the uniformity of the phosphor layer 2, it is possible to provide the fluorescent lamp 1 with less luminance unevenness.

  Next, the dried paint is fired. The firing temperature may be performed using, for example, a sinter furnace, an electric furnace or the like so that the temperature in the glass tube 4 is about 600 ° C to 700 ° C.

  Next, as usual, after the glass tube 4 is evacuated, the glass tube 4 is filled with mercury and a rare gas, and then both ends of the glass tube 4 are sealed.

Examples of the metal compound constituting the paint include yttrium carboxylate (Y (C _n H _{n + 1} COO) ₃ , n = 5 to 8), yttrium isopropoxide (Y (OC ₃ H ₇ ) ₃ ), tetra An organic metal compound such as ethoxysilane (Si (OC ₂ H ₅ ) ₄ ), metal nitrate, metal sulfate, metal carboxylate, metal β-diketonate complex, and the like can be used.

Below, the case where yttrium caprylate (Y (C ₇ H ₁₅ C00) ₃ ) is used as a metal compound will be described as an example, and the reaction in which the metal compound becomes a metal oxide will be described.

As shown in (Chemical Formula 1), caprylic acid (-OOCC ₇ H ₁₅ ) is substituted with a hydroxyl group (—OH) in hydrolysis of yttrium caprylate, and C ₇ H ₁₅ COOH is generated at the same time. The obtained yttrium compound is dehydrated and polymerized. After this reaction is repeated, the polymer is baked and annealed. In this way, yttrium caprylate becomes yttrium oxide (Y ₂ O ₃ ).

  As shown in FIG. 3, in order to prevent the phosphor particles 2a from being exposed on the surface opposite to the surface facing the glass tube 4 of the phosphor layer 2, for example, a coating material for forming the phosphor layer is used. What is necessary is just to adjust the ratio etc. of the metal compound etc. which are contained in. Alternatively, separately from the phosphor layer-forming coating material, the above-mentioned metal compound-containing coating material not containing phosphor particles is prepared, and the phosphor layer-forming coating material is formed by applying the metal compound-containing coating material after drying and before firing. May be. The same applies to the method of forming the metal oxide layer 5. The metal compound-containing paint includes, for example, the remaining components obtained by removing the phosphor particles from the paint for forming the phosphor layer.

(Embodiment 3)
In Embodiment 3, an example of a light emitting device including an example of the fluorescent lamp of the present invention will be described. Hereinafter, as an example of the light emitting device, a backlight unit constituting a liquid crystal display (LCD) device will be described as an example. However, the light emitting device of the present invention is not limited to this, and may be used for any known display device that requires a light emitting device. In the following description, a direct-type backlight unit in which a plurality of fluorescent lamps are arranged in parallel on the back surface of the LCD panel will be described. The light-emitting device of this embodiment is placed on the back surface of the LCD panel. It may be an edge light type backlight unit in which a fluorescent lamp is disposed on the end face of the light guide plate.

  FIG. 5 is a plan view showing a schematic configuration of the backlight unit 10 according to the present embodiment, FIG. 6 is an AA enlarged sectional view of FIG. 5, and FIG. 7 is a diagram of the backlight unit 10 according to the present embodiment. It is a perspective view. 5 and 7 show a state in which the translucent plate 22 shown in FIG. 6 and the mounting frame 24 to which the translucent plate 22 is attached are excluded. 5-7, the scale between each structural member is not unified.

  As shown in FIGS. 5 and 6, the backlight unit 10 includes an envelope 12, and a plurality of examples of the fluorescent lamp 14 of the present invention are accommodated in the envelope 12. The fluorescent lamp 14 is a U-shaped bent external electrode fluorescent lamp (EEFL: External Electrodes Fluorescent Lamp).

  The envelope 12 includes, for example, a reflecting plate 18, a side wall 20 erected from the peripheral edge of the reflecting plate 18, a mounting frame 24 attached to the side wall 20 so as to face the reflecting plate 18, and a translucent plate 22. The translucent plate 22 is fitted in the mounting frame 24 and is disposed in parallel to the reflecting plate 18. The translucent plate 22 is configured by laminating a light diffusion plate 26, a light diffusion sheet 28, and a lens sheet 30 in this order from the reflection plate 18 side (fluorescent lamp 14 side). Since the mounting frame 24 is formed of a non-translucent material, the light emitted from the fluorescent lamp 14 is extracted from the region where the translucent plate 22 exists, surrounded by a two-dot chain line in FIG. That is, the translucent plate 22 functions as a window that can transmit the light emitted from the fluorescent lamp 14.

  The fluorescent lamp 14 is a dielectric barrier discharge fluorescent lamp in which external electrodes 36 and 38 are attached to the outer periphery of both end portions of the glass tube 34 and the glass tube wall is used as a capacitance. The external electrodes 36 and 38 are formed, for example, by winding a metal foil such as an aluminum foil or a copper foil around the outer periphery of the glass tube 34, depositing a metal on the surface of the glass tube, or applying and baking a conductive paste. ing.

  The phosphor layer 40 is formed on the inner surface of the glass tube 34. However, in order to suppress significant consumption of mercury sealed in the glass tube 34, the phosphor layer 40 is formed avoiding the inner surface of the portion of the glass tube 34 in contact with the external electrodes 36 and 38. The material of the phosphor layer 40 and the formation method thereof are the same as those in the fluorescent lamp of the first embodiment. In the glass tube 34, in addition to mercury, a mixed gas containing neon and argon as a discharge substance (discharge gas) is sealed (both not shown).

  The glass tube 34 has a bent portion 42 bent in a U-shape, and a first straight portion 44 and a second straight portion 46 extending in parallel from the bent portion 42. The second linear portion 46 is longer than the first linear portion 44 in accordance with the arrangement position of the second connector 58 described later.

  As shown in FIG. 7, two elongated insulating plates (a first insulating plate 48 and a second insulating plate 50) are laid on the upper surface of the reflecting plate 18 substantially in parallel. The first insulating plate 48 and the second insulating plate 50 are made of polycarbonate, for example. In this example, instead of the first insulating plate 48 and the second insulating plate 50, a single insulating plate having an area comparable to the total area of the two sheets may be used. A first power supply member 52 for supplying power to the first external electrode 36 is provided on the upper surface of the first insulating plate 48, and a second power supply for supplying power to the second external electrode 38 is provided on the upper surface of the second insulating plate 50. A member 54 is provided.

  The first power supply member 52 includes a plurality of first connectors 56 and a first plate 57 that physically connects and electrically connects the first connectors 56. The number of first connectors 56 corresponds to the number of fluorescent lamps 14. The first plate 57 is attached to the upper surface of the first insulating plate 48. Each first connector 56 is fitted with an external electrode 36 (hereinafter also referred to as “first external electrode 36” for distinction from the external electrode 38). The first connector 56 is composed of sandwiching pieces 56 a and 56 b and plate-like portions (connecting portions 56 c) that connect both the sandwiching pieces 56 a and 56 b, and the remaining plate portion other than the first connector 56 is the first plate 57. Is configured. Each sandwiching piece 56a, 56b can be formed by processing an elongated plate made of a conductive material such as phosphor bronze as follows. A cut is made in the plate material so as to leave two adjacent sides of a rectangle continuous in the longitudinal direction. The pair of cantilever pieces formed in this way is bent substantially perpendicularly to the plate material, and the front end side of each cantilever piece is processed along the outer periphery of the fluorescent lamp. When the first external electrode 36 is fitted to the first connector 56, both the sandwiching pieces 56 a and 56 b bend outward, and the first external electrode 36 is held by the first connector 56 due to its restoring force. .

  Similarly, the second power supply member 54 includes a plurality of second connectors 58 and a second plate 60 that physically connects and electrically connects the second connectors 58.

  A region of the first plate 57 that three-dimensionally intersects with the second linear portion 46 of the glass tube 34 is covered with an insulating sheet 82. The insulating sheet 82 is made of an insulating material such as polycarbonate.

  In the example shown in FIG. 7, a portion of the second linear portion 46 of the glass tube 34 that is close to the second external electrode 38 and the first plate 57 that is electrically connected to the first external electrode 36 are three-dimensionally crossed. is doing. Therefore, the potential difference at the location where the second linear portion 46 and the first plate 57 intersect is large. Therefore, if the insulating sheet 82 is not provided, a leakage current flows from the higher potential to the lower potential at the intersection of the second linear portion 46 and the first plate 57, which causes the fluorescent lamp 14 The brightness will be reduced. Therefore, in order to suppress the leakage current as much as possible, it is preferable to arrange the insulating sheet 82 at the intersection.

  The backlight unit 10 includes an inverter 62, and the inverter 62 is electrically connected to the first plate 57 and the second plate 60 via two lead wires 68 and 70. The inverter 62 as a power supply circuit unit converts 50/60 Hz AC power from a commercial power supply (not shown) into high frequency power and supplies the fluorescent lamp 14 with power. Accordingly, the fluorescent lamps can be supplied with power through the first plate 57 and the second plate 60 by the two conductive lines, and the plurality of fluorescent lamps 14 can be lit in parallel by the single inverter 62.

  A bent portion support member 80 having a “C” -shaped portion corresponding to each fluorescent lamp 14 is attached to the side wall 20. The bent portion support member 80 is made of a resin such as polyethylene terephthalate (PET). Assembling the fluorescent lamp 14 into the envelope 12 includes the first external electrode 36 formed on the outer periphery of both ends of the glass tube 34 after the bent portion 42 of the glass tube 34 is fitted into the “C” -shaped portion. The second external electrode 38 only needs to be fitted into the first connector 56 and the second connector 58, respectively, which is convenient.

  FIG. 8 shows an example of a liquid crystal television as an example of a display device using the backlight unit 10 of the above embodiment. In FIG. 8, for convenience of explanation, a part of the front surface of the liquid crystal television 170 is cut away. The liquid crystal television 170 is, for example, a 32-inch liquid crystal television, and includes a liquid crystal display panel 172 and the like in addition to the backlight unit 10. The liquid crystal display panel 172 includes a color filter substrate, a liquid crystal, a TFT substrate, and the like, and is driven by a drive module (not shown) based on an external image signal to form a color image.

  The envelope 12 of the backlight unit 10 is disposed on the back side of the liquid crystal display panel 172, and the backlight unit 10 irradiates the liquid crystal display panel 172 with light from the back side. For example, the inverter 62 is disposed inside the casing 174 of the liquid crystal television 170 and outside the envelope 12.

  Hereinafter, an example of the present invention will be described more specifically with reference to examples. In addition, this invention is not limited to a following example.

In Example 1, a cold cathode fluorescent lamp having the structure shown in FIG. 1 was produced as follows. First, (Y ₂ O ₃ : Eu), (LaPO ₄ : Tb, Ce), and (BaMg ₂ Al ₁₆ O ₂₇ : Eu) were prepared as three-wavelength phosphors. These blending ratios were adjusted so that the color temperature was 10,000K. A suspension was obtained by dispersing 1 kg of the three-wavelength phosphor in a mixed solvent composed of butyl acetate and turpentine oil. In the mixed solvent, 15 g of NC (nitrocellulose) and 1.5 g of boric acid binder were dissolved in advance before the phosphor was dispersed. The mixing ratio of butyl acetate and turpentine oil in the mixed solvent was 4 g of turpentine oil with respect to 900 g of butyl acetate. To this suspension, yttrium caprylate was added and dissolved by stirring to obtain a coating material for forming the phosphor layer. 15 g of yttrium caprylate was added to 1 kg of the phosphor particles.

  Next, the paint was applied to the inner surface of a glass tube having a tube inner diameter of 2.4 mm, a length of 400 mm, and a wall thickness of 0.2 mm. Application of the coating material to the glass tube was performed by sucking up the liquid from above the upright glass tube. The composition of the glass tube is as follows.

SiO ₂ 69.3%
Al ₂ O ₃ 5.1%
B ₂ O ₃ 15.5%
Li ₂ O 0.48%
Na ₂ O 1.4%
K ₂ O 4.8%
MgO 0.5%
CaO 0.9%
SrO 0.04%
BaO 1.2%
Sb ₂ O ₃ 0.1%
As ₂ O ₃ 0%
TiO ₂ 0.6%
ZrO ₂ 0.1%

Next, air having a temperature of 25 ° C. and a relative humidity of 12% was supplied into the glass tube for about 8 minutes to dry the layer made of the applied paint. The layer was dried while rotating an upright glass tube. The supply amount of warm air was 30 ml / min / cm ² . Then, it baked in the electric furnace set to 670 degreeC. The firing time was 10 minutes. At this time, when the temperature in the glass tube was measured using a thermocouple, it reached 650 ° C.

  Next, the glass tube was evacuated, 3 mg of mercury and gas (Ne: Ar = 95: 5; about 8 kPa) were sealed in sequence, and the glass tube was sealed in order to obtain a fluorescent lamp (a).

Nb was used as the electrode material. The axial length N of the electrode was 5.5 mm, the inner diameter was 1.7 mm, the wall thickness was 0.1 mm, and the distance M from the end face of the glass tube to the electrode 6 was 8.2 mm. Cs ₂ AlO ₃ was used for the emitter.

  When 300 μm square of the phosphor layer was observed with HRSEM, the phosphor particles were cross-linked with a rod-shaped metal oxide (rod-shaped body) having a thickness of 0.2 μm to 1.5 μm. Further, in part, a pair of phosphor particles were cross-linked by a plurality of rod-shaped bodies. The average thickness of the rod-shaped body was 0.5 μm. FIG. 9 shows an HRSEM photograph of the phosphor layer.

  The “average thickness” of the rod-shaped body is the thickness at a half of the longitudinal length of each rod-shaped body of a plurality of rod-shaped bodies observed when 300 μm square is observed with HRSEM. It is a value obtained by measuring and arithmetically averaging them.

When the lamp luminance was measured using a color luminance meter (manufactured by TOPCON, SR-3 model number), the initial luminance was 36835 cd / m ² . Assuming that the initial luminance is 100%, the luminance maintenance rate at the time of lighting for 2000 hours is 90%. The lighting frequency was 55 kHz, and the lamp current was constant at 6 mA.

(Comparative Example 1)
A fluorescent lamp (b) was produced in the same manner as in Example 1 except that only butyl acetate was used as the solvent constituting the coating material for forming the phosphor layer.

As in Example 1, when the phosphor layer was observed with an HRSEM, the phosphor particles were cross-linked by a lump of metal oxide. The thickness of the lump was 2 μm or more. The initial luminance was 34260 cd / m ² , and the luminance maintenance rate when lit for 2000 hours was 92%. Here, the “thickness” of the lump is the thickness at a half of the length in the direction between the phosphor particles cross-linked by the lump.

  As described above, both the luminance maintenance ratios after 2000 hours of lighting of the fluorescent lamp (a) and the fluorescent lamp (b) were as high as 90% or more. Thereby, it was confirmed that the fluorescent lamp (a) has a mercury barrier effect substantially equivalent to that of the fluorescent lamp (b). Further, when the fluorescent lamp (a) and the fluorescent lamp (b) are compared, the fluorescent lamp (a) is 2% lower in luminance maintenance rate than the fluorescent lamp (b), but the initial luminance is the fluorescent lamp (b). It was about 7% higher than that. From the above, it was confirmed that the fluorescent lamp (a) secures higher luminance while suppressing the consumption of mercury than the fluorescent lamp (b).

  In Example 2, fluorescent lamps (c) to (g) were produced in the same manner as in Example 1 except that the humidity of the gas supplied into the glass tube was changed when the coating layer was dried.

  A gas having a humidity of 40%, 15%, 10%, 8%, and 5% at 25 ° C. was used as the gas. In this embodiment, since a gas at 25 ° C. is used, the humidity in the glass tube while the gas is supplied is maintained at 40%, 15%, 10%, 8%, and 5%.

  For the fluorescent lamps (c) to (g), the uniformity of the phosphor layer thickness was examined. First, the fluorescent substance layer was observed over the full length of each fluorescent lamp with the HRSEM. For fluorescent lamps (f) and (g) where the paint was dried using a gas having a humidity of less than 10% at 25 ° C., the paint was dried using a gas having a humidity of 10% to 40% at 25 ° C. Greater thickness unevenness was observed for the phosphor layer than the fluorescent lamps (c) to (e) performed. Specifically, voids were generated in the phosphor layer as if the paint slipped off during drying, and as a result, irregularities were observed in the phosphor layer 2. On the other hand, for the fluorescent lamps (c) to (e), the thickness of the phosphor layer 2 was substantially constant (18 μm ± 2 μm) over the entire length in the longitudinal direction.

  Next, the number of contacts between the phosphor layer and the glass tube at a predetermined location was observed with HRSEM. The predetermined portion is on a straight line having a length of 1 mm extending from one end of both ends of the phosphor layer, and the one end is an end disposed on the upper side when the paint is applied. A large number of contacts (pieces / mm) at this location means that the degree of paint dripping is small and the uniformity of the phosphor layer thickness and the like is good.

  FIG. 10 shows the relationship between the humidity in the glass tube and the number of contacts. The number of contacts was 163 at 40% humidity, 165 at 15% humidity, 160 at 10% humidity, 70 at 8% humidity, and 60 at 5%. From this result, in the step of forming the phosphor layer, the vaporization of the solvent is performed while supplying a gas having a humidity of 10% to 40% at 25 ° C. into the glass tube. It was confirmed that can be formed.

  The fluorescent lamp of the present invention is suitable as a light source for a light-emitting device or the like that constitutes a lighting device or a display device because it suppresses mercury consumption and achieves high luminance.

Sectional drawing which shows an example of the fluorescent lamp of this invention The expansion conceptual diagram which shows an example of the fluorescent substance layer which comprises the fluorescent lamp of this invention The expansion conceptual diagram which shows another example of the fluorescent substance layer which comprises the fluorescent lamp of this invention The flowchart explaining an example of the manufacturing method of the fluorescent lamp of this invention The top view which shows an example of the light-emitting device of this invention AA sectional view of FIG. The perspective view which shows an example of the light-emitting device of this invention The perspective conceptual diagram which shows an example of the display apparatus of this invention HRSEM photograph of the phosphor layer constituting the fluorescent lamp of Example 1 Graph showing the relationship between the humidity in the glass tube when drying the paint layer and the number of contacts between the phosphor layer and the glass tube Enlarged conceptual diagram showing an example of a phosphor layer constituting a conventional fluorescent lamp

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fluorescent lamp 2 Phosphor layer 2a Phosphor particle 2b Rod-shaped body 3 Lead wire 3a Internal lead wire 3b External lead wire 4,34 Glass tube 5 Metal oxide layer 10 Backlight unit 170 Liquid crystal television

Claims (14)

A translucent container;
Mercury sealed in the translucent container;
A phosphor layer formed on the inner surface of the translucent container,
The phosphor layer includes a phosphor particle and a rod-like body that contains a metal oxide and crosslinks the phosphor particle.   The fluorescent lamp according to claim 1, wherein a pair of adjacent phosphor particles are cross-linked by a plurality of the rod-shaped bodies.   The fluorescent lamp according to claim 1, wherein a thickness of the rod-shaped body is 1.5 μm or less.   The fluorescence according to any one of claims 1 to 3, wherein the metal oxide includes at least one selected from the group consisting of Y, La, Hf, Mg, Si, Al, P, B, V, and Zr. lamp. The fluorescent lamp according to claim 1, wherein the metal oxide contains Y ₂ O ₃ .   The fluorescent lamp according to any one of claims 1 to 5, wherein the translucent container is a glass tube having an inner diameter of 1.2 mm to 13.4 mm. A paint in which phosphor particles are dispersed in a solvent and a metal compound is dissolved in the solvent is applied to the inner surface of the translucent container, and after the solvent contained in the applied paint is vaporized, the paint is heated. A phosphor layer forming step of forming a phosphor layer in which the metal compound is a metal oxide and the phosphor particles are cross-linked by a rod-shaped body containing the metal oxide;
A mercury sealing step of sealing mercury in the translucent container after the phosphor layer is formed,
The method for producing a fluorescent lamp, wherein the solvent contains two or more solvents having different boiling points.   The method of manufacturing a fluorescent lamp according to claim 7, wherein the metal compound is an organometallic compound.   The method of manufacturing a fluorescent lamp according to claim 8, wherein the organometallic compound includes yttrium carboxylate.   The method for producing a fluorescent lamp according to claim 9, wherein in the phosphor layer forming step, the solvent is vaporized while supplying a gas having a humidity of 10% to 40% at 25 ° C. into the translucent container.   The method for producing a fluorescent lamp according to claim 10, wherein the flow rate of the gas is 16 ml / min to 48 ml / mis per square millimeter. A plurality of fluorescent lamps;
An envelope having a window portion in which the plurality of fluorescent lamps are housed and capable of transmitting light emitted by the plurality of fluorescent lamps;
Each fluorescent lamp is the fluorescent lamp of any one of Claims 1-11, The light-emitting device characterized by the above-mentioned. A display panel;
A display device comprising: the light emitting device according to claim 12 disposed on a back surface of the display panel.   The display device according to claim 13, wherein the display device is a liquid crystal display device.