JP2008117709A - Fluorescent lamp, back light unit, liquid crystal display device, and method of manufacturing fluorescent lamp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fluorescent lamp in which reduction of a brightness maintenance factor can be suppressed and a phosphor layer is hardly peeled off, and to provide a method of manufacturing the fluorescent lamp. <P>SOLUTION: The fluorescent lamp includes a glass tube 61 having in the inner face the phosphor layer 51 containing phosphor particles, including a protection layer to protect the phosphor particles, and a binder to mutually bind the phosphor particles. Formation of the phosphor layer 51 is carried out through steps ((a) and (b)) of forming a first dry layer 65 by coating/drying a first suspension liquid 63 containing a material for the phosphor particles and a material for the binder on the glass tube 61, a step ((c)) of forming a base layer 67 comprised by calcining the first dry layer 65, steps ((d) and (e)) of forming a second dry layer in which a second suspension liquid 69 containing organic metal compound for the protection layer is coated/dried on the base layer 67, and a protection layer forming step of forming the protection layer by calcining the second dry layer 71. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fluorescent lamp in which a phosphor layer is formed on the inner surface of a glass tube, a method for manufacturing the fluorescent lamp, a backlight unit using the fluorescent lamp as a light source, and a liquid crystal display device including the backlight unit. About.

  Some phosphor layers of fluorescent lamps have a protective layer in which phosphor particles are coated with a metal oxide, for example. The reason for forming the protective layer is to suppress deterioration of the phosphor particles due to mercury adhesion to the phosphor particles and ultraviolet rays during light emission (for example, Patent Documents 1 and 2). In addition, in order to raise the intensity | strength of a fluorescent substance layer, the binder which binds fluorescent substance particles is contained in the fluorescent substance layer.

In order to utilize the protective layer, the inventors have suspended a phosphor material for phosphor particles, a binding material for the binder, and an organometallic compound for constituting the protective layer. We are investigating phosphor layers formed using liquid. For example, CBB (CaO, BaO, B ₂ O ₃ ) is used as the binder, and yttrium oxide, for example, is used as the metal oxide.
Japanese Patent Publication No. WO2002 / 047112 ("Disclosure of Invention" column) JP 2002-164018 A

  The phosphor layer may be peeled off from the glass tube or cracked in the phosphor layer due to an impact received during the manufacturing process, product packaging, or transportation after shipment. Part of the phosphor layer may fall off the glass tube due to peeling or cracking of the phosphor layer, leading to a reduction in the quality of the fluorescent lamp.

  As a result of investigation by the inventors, it has been found that the phosphor layer in the above examination method is easily peeled off from the glass tube. In other words, in order to increase the binding force of the phosphor layers (phosphor particles), when the binding material in the suspension is increased, the organometallic compound contained in the suspension becomes the binding material during firing. As a result, the phosphor layer is colored brown, yellow, or a mixed color thereof (hereinafter simply referred to as “brown etc.”). This coloring causes a decrease in the luminance of the fluorescent lamp, and in order to ensure a desired luminance, the amount of the binder for increasing the binding force must be limited.

  In addition, the problem of peeling and cracking of the phosphor layer occurs in the same manner for all fluorescent lamps having the phosphor layer. In addition to the lamp having a straight tube shape, the “U” shape and the “U” shape are used. In addition to the lamp in which the electrode is mounted inside the glass tube, a lamp in which the electrode is provided on the outer periphery of the glass tube (so-called external electrode) This can also occur in a type of fluorescent lamp (EEFL).

  In view of the above problems, an object of the present invention is to provide a fluorescent lamp, a backlight unit, a display device, and a method for manufacturing the lamp, in which the phosphor layer hardly peels off while suppressing a decrease in luminance maintenance rate. To do.

  In order to achieve the above object, a method for manufacturing a fluorescent lamp according to the present invention includes phosphor particles, a binder that connects the phosphor particles, and the phosphor particles bound by the binder. A fluorescent lamp manufacturing method in which a phosphor layer having a protective layer to be protected in a state is formed on the inner surface of a glass tube, wherein the phosphor layer is formed by firing to bind the phosphor particles to the binder A base layer forming step for forming a base layer containing a body, and a protective layer made of a metal oxide by applying and drying a suspension containing an organometallic compound for the protective layer on the base layer, followed by baking. The protective layer is formed through a protective layer forming step.

  The shape of the “fluorescent lamp” here is not particularly limited, and may be, for example, a straight tube shape, a “U” shape, a “U” shape, an “L” shape, or other shapes. Further, the electrode may be a cold cathode / hot cathode type provided inside the glass tube or an external type provided outside.

  Further, the protective layer may cover the entire surface of the phosphor particles, or may cover a part of the phosphor particles.

  Alternatively, the organometallic compound includes one or more metals among yttrium, lanthanum, silicon, magnesium, and zirconium. Here, “metal” is a concept including a semi-metal.

  In addition, the organometallic compound is characterized by comprising one or more of metal alkoxide, metal acetylacetonate, and metal carboxylate.

  On the other hand, the fluorescent lamp according to the present invention is a fluorescent lamp in which a phosphor layer is formed on the inner surface of a glass tube, wherein the phosphor layer is composed of phosphor particles and a binder that binds the phosphor particles together. And a protective layer for protecting the phosphor particles, the binder is directly attached to the phosphor particles, and the protective layer is the portion where the binder is not attached to the phosphor particles. The phosphor particles are coated, and the phosphor particles are covered with the binder at the portion where the binder is attached to the phosphor particles.

The protective layer is made of a metal oxide, or the metal oxide contains at least one of yttrium, silicon, lanthanum, magnesium, and zirconium as a metal. Furthermore, the binder is composed of one or more of CBB, CBBP, and B ₂ O ₃ , and the content ratio of the binder to the phosphor particles is 0.5 wt% or more and 3 wt% or less. It is the range of these.

  On the other hand, the backlight unit according to the present invention is characterized in that the above-described fluorescent lamp is mounted as a light source. Furthermore, the liquid crystal display device according to the present invention is mounted with the above-described backlight unit. It is characterized by that. Here, the “liquid crystal display device” includes a liquid crystal color television, a liquid crystal monitor for a computer, a small display device for portable use and a vehicle use, and the like.

  In the method for manufacturing a fluorescent lamp according to the present invention, the binding material is baked in a state in which no organometallic compound is contained. Thereby, it has been confirmed by experiments that coloring of the phosphor layer can be suppressed. Therefore, since the reaction between the organometallic compound and the binding material can be suppressed, the amount of the binder in the phosphor layer can be increased. This makes it possible to obtain a strong phosphor layer that is difficult to peel off from the glass tube.

  In addition, even if the amount of the binding material is increased, the reaction with the organometallic compound can be suppressed according to the present production method, so that the phosphor layer is also less colored and the decrease in the luminance maintenance rate can be prevented. it can.

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

1. Regarding Configurations Hereinafter, a backlight unit and a liquid crystal display device using the lamp according to the present invention will be described.

1-1. 1. Configuration of Liquid Crystal Display Device FIG. 1 is a diagram showing a liquid crystal display device according to the invention, and is partially cut away so that the inside can be seen.

  The liquid crystal display device 1 is, for example, a liquid crystal color television, and a liquid crystal screen unit 3 and a backlight unit 5 are incorporated in a housing 4. The liquid crystal screen unit 3 includes, for example, a color filter substrate, a liquid crystal, a TFT substrate, a drive module and the like (not shown), and displays a color image on the screen 6 of the liquid crystal screen unit 3 based on an image signal.

1-2. 2. Configuration of Backlight Unit FIG. 2 is a schematic perspective view of the backlight unit, in which a part of the front panel is cut away so that the inside can be seen. The backlight unit 5 is a so-called direct type unit that directly irradiates the liquid crystal screen unit 3 from the back side thereof.

  The backlight unit 5 includes fluorescent lamps (hereinafter referred to as “fluorescent lamps”) that are bent in a “U” shape arranged in a plurality of rows (for example, 5 rows) at intervals in a predetermined direction (here, the short direction of the unit). The lamps are referred to as “bending lamps” 7a, 7b, 7c, 7d, 7e (hereinafter, when it is not necessary to distinguish between the bending lamps, only the sign “7” is used), and these bending lamps 7 are accommodated. A housing 9 and a front panel 11 covering the front surface (opening) of the housing 9 are provided. In FIG. 2, description of fixing means, wiring, and the like of the bending lamp 7 is omitted.

  The bottom plate 13 of the housing 9 is a reflecting plate that reflects light emitted from the bent lamp 7 to the back side (bottom plate 13 side) to the front side of the housing 9. For example, polyethylene terephthalate (PET) is used. It is used. The side plate 15 constituting the housing 9 is also made of the same resin as the bottom plate 13.

  The front panel 11 is for diffusing the light from each bending lamp 7 and extracting it as parallel light (in the normal direction of the front panel 11). The front panel 11 includes, for example, a diffusion plate 17, a diffusion sheet 19, and a lens sheet 21. ing.

  As the screen of the liquid crystal display device is enlarged, a polycarbonate (PC) material with good dimensional stability is used for the diffusion plate 17. When the screen size is small, an acrylic material can be used.

1-3. FIG. 3A is a diagram showing a bent lamp, and a plurality of bent lamps are cut away so that the configuration of the internal electrodes and the like can be understood.

  The bent lamp 7 has electrodes 33 and 35 sealed to the end portions 31a and 31b of one glass tube 31, and has a “U” shape having two bent portions 34 and 36. Extending portions 37, 39 and an intermediate portion 41 positioned between one ends (bending portions 34, 36) of the pair of extending portions 37, 39.

  The electrodes 33 and 35 are so-called cold cathode types and include bottomed cylindrical electrode bodies 33a and 35a and electrode bars 33b and 35b attached to the bottoms of the electrode bodies 33a and 35a. 33b and 35b are sealed to end portions 31a and 31b of the glass tube 31 through bead glasses 33c and 35c.

  The discharge space 40 formed inside the glass tube 31 sealed at both ends is filled with, for example, a predetermined amount of mercury, rare gas (eg, argon, neon), or the like. Note that the rare gas is sealed in a reduced pressure state.

  The glass tube 31 has a circular cross-sectional shape, for example, and a phosphor layer 51 is formed on the inner surface. The glass tube 31 is made of, for example, borosilicate glass. For example, a glass tube 31 having an outer diameter of 3 (mm) and an inner diameter of 2 (mm) is used, and the tube at the bent portion (here, the bent portion 34) of the glass tube 31 is used. The radius of curvature R of the axis X is 4 (mm).

  FIG. 3B is an enlarged view of the phosphor layer formed on the inner surface of the glass tube. The phosphor layer in FIG. 3B is a conceptual diagram.

  The phosphor layer 51 includes, for example, three-wavelength phosphor particles 53, a binder 54 that binds (couples) the phosphor particles 53, and phosphor particles 53 that are bound by the binder 54. And a protective layer 55 covering the binder 54 together.

  In the case where the binder 54 in the phosphor particles 53 is attached, the protective layer 55 is not formed on the portion where the phosphor particles 53 and the binder 54 are attached, and the phosphor particles 53 are not formed. In the case where the binder 54 in the phosphor particles 53 is not adhered, the phosphor particles 53 are formed so as to be covered directly by the protective layer 55. Has been.

  However, not all phosphor particles 53 are covered with the protective layer 55, and some of the individual phosphor particles 53 may not be covered with the protective layer 55. The formation of the phosphor layer 51 will be described later.

As the phosphor particles 53, for example, rare earth phosphor particles are used. Here, red-emitting europium co-activated yttrium oxide [Y ₂ O ₃ : Eu ³⁺ ] (abbreviation: YOX), green-emitting cerium, Terbium co-activated lanthanum phosphate [LaPO ₄ : Ce ³⁺ , Tb ³⁺ ] (abbreviation: LAP) and blue emission europium-activated barium magnesium aluminate [BaMg ₂ Al ₁₆ O ₂₇ : Eu ²⁺ ] (abbreviation: BAM) The following three types are used.

  The phosphor layer 51 has a structure in which part of the phosphor particles 53 is embedded by firing when forming a phosphor layer described later.

  The binding body 54 is, for example, CBB. The binding body 54 mainly binds the phosphor particles 53 to each other.

  The protective layer 55 is made of a metal oxide, for example, yttrium oxide. This protective layer 55 covers substantially the entire surface of the phosphor particles 53. The purpose of the protective layer 55 is to prevent mercury in the discharge space 40 from adhering to the phosphor particles 53 and being deteriorated by ultraviolet rays from mercury. The protective layer 55 preferably covers the entire surface of the phosphor particles 53. However, if a part of the surface of the phosphor particles 53 is coated, the protective layer 55 is more effective (mercury adhesion / ultraviolet light than the case where it is not coated at all). Deterioration prevention) is obtained.

The protective layer 55 is formed of an organometallic compound, here, yttrium carboxylate [Y (C _n H _{2n +} ), in a suspension (corresponding to a first suspension described later) for forming the phosphor layer 51. ₁ COO) ₃ ] is contained, and is thermally decomposed in the baking step to become yttrium oxide, which covers the phosphor particles 53 and the binder 54. The carboxylic acid here is caprylic acid.

2. About the manufacturing method of a bending lamp First, the manufacturing method of a bending lamp is demonstrated, and the shaping | molding method about a fluorescent substance layer is demonstrated in detail after that.

2-1. About the manufacturing process of a bending lamp FIG. 4: is a figure explaining the manufacturing process of a bending lamp.

  The bent lamp includes a phosphor layer forming step of forming the phosphor layer 51 on the inner surface of the glass tube 61 to be the glass tube 31 of the bent lamp 7, and end portions 61a of the glass tube 61 on which the phosphor layer 51 is formed. It is obtained through a sealing step of sealing the electrodes 33 and 35 to 61b and a bending step of bending the straight glass tube 61 into a “U” shape.

  In FIG. 4, a description is given of a cutting process for cutting the glass tube 61 on which the phosphor layer 51 is formed to a predetermined length, a sealing process for sealing mercury, a rare gas, and the like in the glass tube 61. In addition, since these steps are the same as those in the prior art, description thereof is omitted here. Further, the phosphor layer forming step will be described later, and the sealing step is the same as the conventional one, and thus the description thereof is omitted here.

  In the bending step, for example, the planned bending portion and its peripheral portion in the glass tube 61 are heated using, for example, a heater or the like wound (or arranged) on the outer periphery of the peripheral portion, and the glass of the heating portion is heated. When the temperature of the tube 61 is about 750 (° C.) to 760 (° C.), the tube 61 is bent so that both side portions thereof are substantially perpendicular with the planned bending portion as a center. The softening point of the glass tube 61 is 760 (° C.).

2-2. Phosphor Layer Formation Step FIG. 5 is a diagram for explaining the phosphor layer formation step in the manufacturing process of the bent lamp.

  The phosphor layer 51 is coated with a first application step ((a) in the drawing) in which a first suspension 63 containing a phosphor material, a binding material, and the like is applied to the inner surface of the glass tube 61. A first drying step ((b) in the figure) for drying one suspension 63 to form a first drying layer 65, and firing the first drying layer 65 to form a first firing layer 67 (" A first firing step ((c) in the figure) for forming a “base” layer) and a second coating step for applying a second suspension 69 containing yttrium caprylate or the like on the first fired layer 67 ( (D) in the drawing, and the second drying 69 including the first fired layer 67 by drying the upper surface (surface) of the first fired layer 67 and the second suspension 69 that has penetrated into the first fired layer 67. A second drying step ((e) in the figure) for forming the layer 71 and a second firing step ((f in the figure) for firing the second dry layer 71 to form the phosphor layer 51. ) Through the formed.

(1) First coating process ((a) of FIG. 5)
The first suspension 63 includes an organic solvent, a phosphor material, a binding material, a thickener, and the like. In this embodiment, butyl acetate is used as the organic solvent, the same material as the phosphor particles is used as the phosphor material, the binder is used as the binding material, and nitrocellulose is used as the thickener.

  Note that the phosphor material and the binding material here are substantially the same components as the phosphor particles and the binder after firing, that is, the material of the material before and after firing is not changed. You may use the material from which a component changes with before and after baking.

The amount of each substance constituting the first suspension 63 is 1 (kg) when the phosphor particles (total amount of three wavelengths) are 1 (kg).
CBB ... 5-15g (for example, 10g)
Nitrocellulose ... 5-25g (for example, 15g)
Butyl acetate: Adjustment is made so that the amount of phosphor particles attached becomes appropriate. In addition, butyl acetate is adjusted, for example so that the adhesion amount of a fluorescent substance particle may be 2.5-4.0 (mg / cm < ² >) (for example, 3.5 mg / cm < ² >).

  For example, the first suspension 63 is applied to the inner surface of the glass tube 61 by, for example, sucking the first suspension 63 from the lower end opening of the vertically standing glass tube 61 and then the first suspension in the glass tube 61. This is performed by discharging the liquid 63.

  Specifically, first, a tank for storing the first suspension 63 is prepared, and the glass tube 61 is set upright. Then, with the lower end portion of the glass tube 61 immersed in the first suspension 63 in the tank, the internal air is exhausted from the upper end of the glass tube 61 by a suction force such as a vacuum pump. Thereby, the first suspension 63 in the tank is sucked into the glass tube 61.

  While the liquid surface of the first suspension 63 in the glass tube 61 reaches the upper end of the glass tube 61 (predetermined height), the suction of the first suspension 63 is stopped and released to the atmosphere, and then the glass tube 61 is pulled up from the first suspension 63, and the first suspension 63 inside is discharged from the inside of the glass tube 61. Thereby, the first suspension 63 is applied in a film shape to a predetermined region on the inner periphery of the glass tube 61.

(2) First drying step ((b) of FIG. 5)
In the first drying step, the first suspension 63 applied in the first application step is dried. As an example of drying, it is performed by blowing warm air from the upper end of the glass tube 61 in the standing state. The hot air is determined by the inner diameter and length of the glass tube 61, the type and viscosity of the organic solvent in the first suspension 63, and the temperature of the hot air in the present embodiment is room temperature 25 (° C.). It is controlled in a range of ˜40 (° C.) (for example, 30 ° C.).

  As described above, the amount of hot air and the time to blow are also determined by the dimensions of the glass tube (inner diameter, length, etc.), the suspension configuration (type of organic solvent, viscosity, etc.), the temperature of the hot air, etc. However, the air volume in the present embodiment is in the range of 50 (ml / min) to 200 (ml / min) (for example, 120 ml / min), and the blowing time is in the range of 5 (min) to 20 (min). (For example, 15 min).

(3) 1st baking process ((c) of FIG. 5)
In the first firing step, the first dry layer 65 formed in the first drying step is fired. As an example of firing, the glass tube 61 is placed in an atmosphere (for example, a heating furnace) at a predetermined temperature for a predetermined time.

  Both the predetermined temperature and the predetermined time are determined by the dimensions (inner diameter, length, etc.) of the glass tube 61, the type of the phosphor particles 53, the type of the organometallic compound, etc. The temperature in this embodiment is 600 ( C.) to 700 (° C.) (for example, 650 ° C.), and the time is 10 to 20 minutes (for example, 15 minutes).

  By completing the first firing step, the base layer 67 in a state where the phosphor particles 53 are connected by the binder (CBB) is formed. In addition, the process combining the above “first coating process, first drying process, and first baking process” corresponds to the base layer forming process of forming the base layer of the present invention. Further, after the formation of the base layer, the content ratio of the binder to the phosphor particles is 1.0 (wt%).

(4) Second coating process ((d) of FIG. 5)
The second suspension 69 includes an organic solvent, an organometallic compound, and the like. In this embodiment, butyl acetate is used as the organic solvent, and yttrium caprylate is used as the organometallic compound, for example. The second suspension 69 is adjusted with butyl acetate and yttrium caprylate so that the concentration is in the range of 0.1 to 2% (for example, 1.0%) in terms of yttrium oxide.

  The application of the second suspension 69 on the base layer 67 is the same as the first application process described above. When this coating process is completed, the second suspension 69 enters the gap (for example, the gap between the phosphor particles and the phosphor particles) of the base layer 67 formed in the first firing process, The second suspension 69 is applied to the surface.

  In FIG. 5D, the base layer 67 and the second suspension 69 are not distinguished from each other and are collectively shown as the second suspension 69.

(5) Second drying step ((e) of FIG. 5)
In the second drying step, the second suspension 69 applied in the second application step is dried. The drying conditions are the same as those in the first drying step except that the amount of warm air is controlled in the range of 50 (ml / min) to 400 (ml / min) (for example, 200 ml / min). As a result, the second dry layer 71 is formed, and the yttrium caprylate covers the phosphor particles bound by the binder together with the binder. At this time, the yttrium caprylate that has passed through the gap between the phosphor particles 53 and reached the inner surface of the glass tube 61 adheres to the inner surface of the glass tube 61 as it is.

  The second dry layer 71 is a layer in which yttrium caprylate is attached to the base layer 67. In FIG. 5E, the second dry layer 71 is not distinguished from the base layer 67 and the second dry layer 71. A dry layer 71 is shown.

(6) Second firing step ((f) in FIG. 5)
In the second firing step, the second dry layer 71 formed in the second drying step is fired. The firing conditions are the same as in the first firing step. By completing the second firing step, yttrium caprylate is converted into glassy yttrium oxide in the firing step, and the protective layer 55 is formed. In addition, this protective layer 55 becomes glassy, and as shown in FIG. 3 (b), the phosphor particles 53, the binder 54 attached to the phosphor particles 53, or even glass. The inner surface of the tube 61 is covered.

  In addition, the process which combined said "2nd application | coating process, 2nd drying process, and 2nd baking process" becomes "the protective layer formation process" of this invention. Further, the formation of the phosphor layer 51 according to the present invention is completed by the above steps.

3. Coloring of the phosphor layer When the phosphor layer is molded using a suspension containing phosphor material (phosphor particles), binding material (binder), organometallic compound, etc., the phosphor layer It is considered that the cause of the coloration is that the organometallic compound reacts with the binding material (binder) in the firing step after applying and drying the suspension.

That is, in the suspension for forming the phosphor particles (53) and the protective layer (55) on the inner surface of the glass tube (61), the binding material (binder CBB ( 54)). B ₂ O ₃ contained in the CBB reacts with an organic component (C _n H _{n + 1} ) of yttrium caprylate contained in the suspension at the time of firing performed after the suspension is dried. As a result, the carbon component remains and is colored brown or the like.

As described in the section “Problems to be Solved by the Invention”, this B ₂ O ₃ causes the phosphor layer to change color to brown or the like, resulting in a decrease in luminance (decrease in luminance maintenance rate). Become.

  In order to prevent coloring during firing, it is easiest to reduce the amount of the binder. However, if the amount of the binder is reduced, the binding force for binding the phosphor particles and the binding force between the phosphor layer and the inner surface of the glass tube are weakened, and the phosphor layer is easily peeled off from the inner surface of the glass tube. .

  Therefore, the inventors have studied a method in which the phosphor layer is not colored without reducing the amount of the binder, and as a result, after firing the binding material, the phosphor particles and the binder with the organometallic compound. It was found that the binder and the organometallic compound did not react when coated. That is, it was found that the binder reacts with the organometallic compound before firing the binder, but does not react with the organometallic compound after firing.

  The reason for this is considered to be that the surface of the binding material and the surface area of the binder are different (changed) before and after the firing step. Since a plurality of binding materials before firing are gathered in a particulate form, the surface area of the binding material is the sum of the surface areas of the plurality of particles. On the other hand, the binder after firing becomes a lump (a lump) that is melted from the particle state to become an integral lump by the heat at the time of firing, so that the surface area of the binder is equal to the surface area of the lump. Total. Since the binder after firing has no or few voids inside, the surface area of the binder is smaller than that before firing and the reaction with the organometallic compound is considered to be suppressed.

  FIG. 6 is a diagram for explaining a state change at the time of forming the phosphor layer of the binder according to the present invention.

  First, as described above, the binding material in the first suspension 63 is mixed with an organic solvent in the form of particles, and when applied to the glass tube 61 and dried, as shown in FIG. The binding material 54a is attached to the phosphor material 53a and the inner surface of the glass tube 61 in the form of particles. In addition, the state shown to (a) of FIG. 6 is the 1st dry layer 65, and the organometallic compound is not contained in this 1st dry layer 65. FIG.

  Next, the first dry layer 65 is fired. FIG. 6B shows the first fired layer 67 in a state after firing. The binding body 54 of the first fired layer 67 was in a state in which the particles of the binding material 54a were bonded to each other before firing, but the firing material 54a melted and changed to a lump state by firing. Yes.

  In this state, the surface area of the binder 54 after firing (b) has a smaller surface area than the state of the binding material 54a before firing (a). The adjacent phosphor particles 53 or the phosphor particles 53 and the glass tube 61 are bound (bonded) through a single bundle 54.

  Further, the phosphor particles 53 enter the glass tube 61 (partly buried), and the phosphor particles 53 are fixed to the glass tube 61. Thereby, the bonding force between the phosphor particles 53 and the glass tube 61 is increased.

  Even if the second suspension 69 containing the organometallic compound is applied, dried and baked in a state where the bound body 54 is in one lump, the organometallic compound remains in the bound body 54 for the reasons described above. As shown in FIG. 6 (c), the phosphor particles (53) and the binder 54 are collectively covered. The black particles in FIG. 6C are for showing a state in which the protective layer 55 covers the phosphor particles (53) and the binder 54.

4). Performance Test The inventors have investigated the lamp characteristics (luminance, luminance maintenance ratio) and the performance of the phosphor layer (phosphor layer, luminance maintenance rate) for the phosphor layer formed by the conventional method and the phosphor layer formed by the method described above. Specifically, the light source layer was peeled when the glass tube was bent.

  Here, a conventional phosphor layer will be described.

  A conventional phosphor layer is formed by applying and drying a suspension containing a phosphor material (phosphor particles), a binding material (binder), and an organometallic compound on the inner surface of a glass tube, followed by firing. Forming. The phosphor material, the binding material, and the organometallic compound are the same as those described in the embodiment.

The amount of each substance constituting the suspension for a conventional phosphor layer is 1 (kg) when the phosphor particles (total amount of three wavelengths) are 1 (kg).
CBB ・ ・ ・ 0.2g
Nitrocellulose ... 15g
Yttrium caprylate ・ ・ ・ 0.2g
Butyl acetate: Adjustment is made so that the amount of phosphor particles attached becomes appropriate. In addition, butyl acetate is adjusted, for example so that the adhesion amount of fluorescent substance particle may be 2.5 mg / cm < ² >, for example.

  The above suspension is applied to the inner surface of the glass tube under the same conditions as in the first application step, the suspension applied under the same conditions as in the first drying step is dried, and the dried layer is applied to the first firing step. By firing under the same conditions, a conventional phosphor layer is formed.

  The amount of the binder in the conventional phosphor layer is smaller than the amount of the binder in the phosphor layer according to the invention. If the amount of the binder is further increased, as described in the background section. This is because the phosphor layer is colored.

4-1. About Coloring The phosphor layer according to the invention and the phosphor layer according to the related art were each formed on 100 glass tubes. As a result of visual evaluation of these glass tubes, coloring was not observed in both phosphor layers.

4-2. Lamp characteristics A lamp was manufactured using the glass tube on which the above two types of phosphor layers were formed. Among the manufactured lamps, a lamp having the phosphor layer according to the invention is called an invention product, and a lamp having a conventional phosphor layer is called a conventional product.

  The inventive product and the conventional product were turned on under the same conditions (lamp current 5 (mA), ambient temperature 25 ± 1 (° C.)), and the luminance and luminance maintenance rate of each lamp were measured. The luminance maintenance ratio is a luminance ratio after 2000 hours of lighting with respect to the initial luminance.

The lamp characteristics of the invention are
Luminance ... 24675 Cd / m ²
Luminance maintenance ratio: 91.5%
It is.

On the other hand, the conventional lamp characteristics are:
Luminance ... 24520 Cd / m ²
Luminance maintenance ratio: 91%
It is.

As can be seen from the above results, the lamp characteristics of the inventive product and the conventional product are considered to be substantially equivalent with almost no difference. This is basically because both the invention product and the conventional product are adjusted so that the adhesion amount of the phosphor particles is 2.5 (mg / cm ² ) to 4.0 (mg / cm ² ). This is probably because the amount of phosphor particles adhering to the glass tube is substantially the same.

  In addition, the amount of the conventional binding material and the organometallic compound is determined by giving priority to the lamp luminance and luminance maintenance ratio over the phosphor layer strength (peeling from the glass tube, etc.). The invention product has approximately the same lamp characteristics as the conventional product that prioritizes the lamp characteristics.

4-3. Peeling of the phosphor layer Peeling of the phosphor layer is performed at two locations of the straight tubular glass tube on which the phosphor layer is formed, and the radius of the inner surface of the glass tube (R1 in FIG. 3A). Is bent to approximately 90 (°) so that the thickness becomes 5 (mm) (the shape of the glass tube after bending is substantially “U” -shaped), and then the “U” -shaped glass tube is the main plate. It was carried out by dropping from a height of 30 (cm) onto a flat plate in a state parallel to the surface. That is, the presence or absence of peeling of the phosphor layer was evaluated by dropping the glass tube.

  The glass tube in which the phosphor layer according to the invention is formed and the glass tube in which the conventional phosphor layer is formed have the same specifications, and a predetermined portion of the glass tube is curved to 90 (°). The conditions are the same.

The glass tubes used for the experiment were 100 glass tubes with the conventional phosphor layer formed and the glass tube with the phosphor layer according to the invention formed.
Glass tube having phosphor layer according to invention ... 0 pieces
45 glass tubes having conventional phosphor layers.

  As shown by the above results, 45 of the 100 phosphors occurred in the conventional phosphor layer, but no peeling occurred in the phosphor layer according to the invention.

  This limits the amount of the binder (binding material) because the conventional phosphor layer is colored during firing. For this reason, in the range which does not generate | occur | produce coloring at the time of baking, the quantity of a binder is small and peeling of a fluorescent substance layer will generate | occur | produce.

  On the other hand, in the phosphor particles according to the invention, the first dry layer (phosphor material and binding material) obtained by drying the first suspension is fired and then the organometallic compound is contained. Since the phosphor layer is formed by firing the second dry layer formed by applying and drying the two suspensions, the phosphor layer is difficult to be colored. For this reason, it is possible to increase the binder content compared to the conventional phosphor layer used in the performance test, and to suppress the peeling of the phosphor layer while maintaining substantially the same characteristics as the lamp characteristics of the conventional product. It is thought that.

  As described above, the present invention has been described based on the embodiment. However, the present invention is not limited to the above-described form, and for example, the following form is also possible.

1. About the lamp 1-1. Regarding types In the above-described embodiment, a cold cathode fluorescent lamp (CCFL) has been described as an example. However, the present invention is not limited thereto, and is applicable to a so-called external electrode fluorescent lamp. The external electrode fluorescent lamp is, for example, a dielectric barrier discharge fluorescent lamp (EEFL: External Electrodes Fluorescent) in which an external electrode is provided on the outer periphery of the glass tube at both ends of the glass tube and the glass tube wall is used as a capacitance instead of the internal electrode. Lamp).

  In an external electrode fluorescent lamp, the electric field strength at the electrode portion is increased, and mercury in the discharge space is attracted to the electrode, so that it easily adheres to the phosphor particles, and the mercury in the discharge space that contributes to light emission is consumed. However, it tends to be short-lived. When the present invention is applied to the lamp, the phosphor particles are covered with a protective layer, so that mercury attracted to the electrodes can be prevented from adhering to the phosphor particles, and consumption of mercury can be prevented. Can do.

  Further, the present invention can be applied to a fluorescent lamp using a hot cathode electrode, and can also be applied to a bulb-type fluorescent lamp and a compact fluorescent lamp.

1-2. About shape In the said embodiment, although the glass tube of the fluorescent lamp was carrying out "U" shape, of course, you may have another shape. Other shapes include, for example, a straight tube shape, a “U” shape, an “L” shape, a “V” shape, and an annular shape.

  In addition, when applied to a bulb-type fluorescent lamp, the shape of the glass tube is, for example, a spiral shape, a shape in which a plurality of “U” shapes or other shapes are connected or combined, and a plurality of straight tubes are connected. It may have a shape.

  Furthermore, although the cross section of the lamp in the embodiment is circular, other shapes may be used. The other shape may be, for example, a flat shape such as an elliptical shape or an oval shape, or a polygonal shape such as a triangular shape or a square shape. Moreover, the cross-sectional shape of the glass tube may be substantially constant in the longitudinal direction or may be different. As a different example, there is a case where the portion where the electrode is mounted is circular and the middle portion where the electrode is not mounted, ie, a so-called effective light emitting portion is flat. Of course, this may be reversed, or the cross-sectional shape may be a polygonal shape.

1-3. Regarding the specification of the bent portion In the performance test in the above embodiment, the radius of curvature R1 inside the bent portion was 5 (mm) (see FIG. 3A). Is not limited to the radius (5 (mm)), and other radii of curvature may be used.

  According to the study by the inventors, the smaller the radius of curvature, the more the conventional phosphor layer peels from the inner surface of the glass tube, and in particular, the radius of curvature (R in FIG. 3A) is 4. When it becomes smaller than (mm), the phosphor layer becomes large enough to be visually observed. On the other hand, when the present invention is applied, peeling of the phosphor layer at the bent portion cannot be visually confirmed, and the effect obtained by the present invention is particularly great.

  In addition, when a curvature radius becomes larger than 4 (mm), a curvature will become large and it will become difficult to produce peeling from the inner surface of a glass tube also with the conventional fluorescent substance layer.

1-4. About the presence or absence of bent portions In the above embodiment, the glass tube has bent portions at two locations, but it may have bent portions at one location or three or more locations. It does not have to be, and may be gently curved.

1-5. About glass tube The glass tube of embodiment is not restricted to borosilicate glass, You may use lead glass, lead-free glass, soda glass, etc. FIG. In this case, the dark startability can be improved. That is, the glass as described above contains a lot of alkali metal oxides typified by sodium oxide (Na ₂ O). For example, in the case of sodium oxide, the sodium (Na) component is formed on the inner surface of the glass tube over time. Elute. This is because sodium has a low electronegativity, and sodium eluted at the inner end of the glass tube (without a protective film) is considered to contribute to the improvement of the dark startability.

  In particular, in the external electrode type fluorescent lamp formed so as to cover the external electrode on the outer peripheral surface of the end portion of the glass tube, the content of the alkali metal oxide in the material of the glass tube is 3 (mol%) or more and 20 (mol%). The following is preferred.

  For example, when the alkali metal oxide is sodium oxide, the content is preferably 5 (mol%) or more and 20 (mol%) or less. If it is less than 5 (mol%), the probability that the dark start time exceeds 1 second increases (in other words, if it is 5 (mol%) or more, the probability that the dark start time is within 1 second increases), 20 If the amount exceeds (mol%), the glass tube will become black (brown) or white due to long-term use, resulting in a decrease in brightness, or a decrease in the strength of the glass tube. .

  In consideration of protection of the natural environment, it is preferable to use lead-free glass. However, lead-free glass may contain lead as an impurity in the manufacturing process. Therefore, glass containing lead at an impurity level of 0.1 (wt%) or less is also defined as lead-free glass.

2. 2. About phosphor layer 2-1. Regarding the content of the binder In the above embodiment, CBB is used as the binder, and the content of the binding material in the first suspension is 5 (g) with respect to 1 kg of the phosphor material. ˜15 (g). That is, the content ratio with respect to the phosphor particles is set to about 0.5 (wt%) to 1.5 (wt%).

  However, other materials (refer to “2-3. Types of binder” described later) may be used as the binder (binding material), or phosphor particles different from the embodiment may be used. . Considering these, it is considered that the content ratio with respect to the phosphor particles is preferably in the range of about 0.5 (wt%) to 3.0 (wt%).

  When the amount of the binding material (binder) is less than 5 (g), the number of binders (particles) that bind the phosphor particles or the phosphor particles and the glass tube decreases, and the phosphor particles or This is because the binding force that binds the phosphor particles and the glass tube is reduced, making it impractical. Further, for example, the phosphor layer may be peeled off when the glass tube is bent.

  Moreover, when the amount of the binding material is more than 30 (g), there is a high possibility that the phosphor layer is colored when the organometallic compound is converted into a metal oxide by firing, or the light emitted from mercury is transmitted. This is because the rate becomes worse and the brightness as a lamp decreases.

2-2. About content of organometallic compound In the said embodiment, the density | concentration of the organometallic compound in 2nd suspension is 0.1 (%)-2 (%).

  When the concentration of the organometallic compound is less than 0.1 (%), the amount of metal oxide required to cover almost the entire base layer cannot be obtained, and the phosphor particles are covered and protected. This is because the function cannot be performed.

  Further, when the organometallic compound is larger than 2 (%), there is a high possibility that the phosphor layer is colored when the organometallic compound becomes a metal oxide by firing.

2-3. Regarding types of binders In the above embodiment, CBB, which is a kind of alkaline earth metal borate, is used as the binder, but other materials may be used.

As other materials, CBBP (CaO, BaO, B ₂ O ₃ , Ca ₂ P ₂ O ₇ ), which is a kind of alkaline earth metal borate, and B ₂ O ₃ can be used. .

In this case, it is preferable to mix at a weight ratio such that when CBB is 1, Ca ₂ P ₂ O ₇ has an arbitrary ratio of 0.7 or less. This is because, if the ratio of Ca ₂ P ₂ O ₇ exceeds 0.7, even if the Ca ₂ P ₂ O ₇ ratio is covered with the protective layer, mercury is likely to be adsorbed, and the brightness of the lamp is reduced. In other words, if a CBB that does not contain Ca ₂ P ₂ O ₇ is used as the alkaline earth metal borate, it is possible to suppress a decrease in luminance due to mercury adsorption, compared to the case of using CBBP. It is.

2-4. About the kind of organometallic compound In the said embodiment, although yttrium is used as a metal of an organometallic compound, another material can be used. Other materials include metals and semi-metals such as lanthanum (La), silicon (Si), magnesium (Mg), and zirconium (Zr). Note that yttrium, lanthanum, silicon, magnesium, and zirconium may be used alone, or a plurality of types may be used in combination.

Of the above metals, it is preferable that at least yttrium is contained. This is because mercury (Hg) has a low affinity (difficult to react) with yttrium oxide (Y ₂ O ₃ ).

  On the other hand, the metal oxide metal (metal of the organometallic compound) used as the protective layer cuts ultraviolet rays having a wavelength of 185 (nm) out of ultraviolet rays emitted from mercury, and ultraviolet rays having a wavelength of 254 (nm). It is desirable that the material be able to pass through and hardly react with mercury.

  In the above embodiment, caprylic acid which is a kind of carboxylic acid which is an organic material of an organometallic compound (metal carboxylate) is used, but other materials which are one kind of carboxylic acid can be used. . Other materials include stearic acid, oleic acid, linoleic acid, and the like.

  In particular, since these organic materials have a large molecular weight and contain a large amount of carbon components, the reaction with the binding material CBB increases and the color tends to be colored. In the present invention, the binding in the first suspension is performed. Since the material is fired first, the above material can be used with little risk of coloring.

2-5. Regarding phosphor particles In the above embodiment, YOX, LAP, and BAM are used as the phosphor particles. However, the phosphor particles in the present invention are not limited to those described above, and other phosphor particles. Can also be used.

(1) Ultraviolet light For example, in recent years, with the increase in size of liquid crystal color televisions, polycarbonate with good dimensional stability has been used for the diffusion plate that closes the opening of the backlight unit. This polycarbonate is easily deteriorated by ultraviolet rays having a wavelength of 313 (nm) emitted from mercury. In such a case, phosphor particles that absorb ultraviolet light having a wavelength of 313 (nm) may be used. The blue phosphor particles (BAM) described in the embodiment absorb 313 (nm) ultraviolet rays.

  Examples of phosphor particles that absorb ultraviolet rays of 313 (nm) include the following.

(A) Blue europium / manganese co-activated barium aluminate / strontium / magnesium [Ba _1-xy Sr _x Eu _y Mg _1-z Mn _z Al ₁₀ O ₁₇ ] or [Ba _1-xy Sr _x Eu _{y Mg 2-z Mn z Al} 16 O 27]
Here, x, y, and z are preferably numbers satisfying the conditions of 0 ≦ x ≦ 0.4, 0.07 ≦ y ≦ 0.25, and 0 ≦ z <0.1, respectively. When z = 0 under the above conditions, it becomes europium activated barium aluminate / strontium.

Examples of such phosphor particles include europium-activated barium magnesium aluminate [BaMg ₂ Al ₁₆ O ₂₇ : Eu ²⁺ ], [BaMg ₁ Al ₁₀ O ₁₇ : Eu ²⁺ ] (abbreviation: BAM-B), , Europium activated barium aluminate / strontium / magnesium [(Ba, Sr) Mg ₂ Al ₁₆ O ₂₇ : Eu ²⁺ ], [(Ba, Sr) Mg ₁ l ₁₀ O ₁₇ : Eu ²⁺ ] (abbreviation: SBAM-B) ) Etc.

  This phosphor particle has the same main component as a later-described green phosphor particle, and is used for green depending on the value of z. For this reason, (-B) and (-G) representing colors are added to the end of the abbreviations to distinguish the colors.

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

Examples of such phosphor particles include europium / manganese co-activated barium aluminate / magnesium [BaMg ₂ Al ₁₆ O ₂₇ : Eu ²⁺ , Mn ²⁺ ], [BaMg ₁ Al ₁₀ O ₁₇ : Eu ²⁺ , Mn ^2+]. ] (Abbreviation: BAM-G), europium / manganese co-activated barium aluminate / strontium / magnesium [(Ba, Sr) Mg ₂ Al ₁₆ O ₂₇ : Eu ²⁺ , Mn ²⁺ ], [(Ba, Sr) Mg ₁ Al ₁₀ O ₁₇ : Eu ²⁺ , Mn ²⁺ ] (abbreviation: SBAM-G).

(C) Red • Europium activated phosphorus • Yttrium vanadate [Y (P, V) O ₄ : Eu ³⁺ ] (abbreviation: YPV)
Europium activated yttrium vanadate [YVO ₄ : Eu ³⁺ ] (abbreviation: YVO)
Europium activated yttrium oxysulfite [Y ₂ O ₂ S: Eu ³⁺ ] (abbreviation: YOS)
Manganese-activated magnesium fluoride germanate [3.5MgO.0.5MgF ₂ .GeO ₂ : Mn ⁴⁺ ] (abbreviation: MFG)
Dysprosium-activated yttrium vanadate [YVO ₄ : Dy ³⁺ ] (green and red light emission, abbreviation: YDS)
In addition, you may mix and use the fluorescent substance particle of a different compound with respect to one type of luminescent color. For example, phosphor particles of BAM-B (absorbs 313 nm) only in blue, LAP (does not absorb 313 nm) and BAM-G in green, YOX (does not absorb 313 nm) and YVO (absorbs 313 nm) in red May be used. In such a case, as described above, the phosphor particles that absorb the wavelength 313 (nm) are adjusted so that the total weight composition ratio is larger than 50 (%), so that the ultraviolet rays leak out of the glass tube. Can be prevented.

  Therefore, when phosphor particles that absorb ultraviolet rays of 313 (nm) are included in the phosphor layer, deterioration due to ultraviolet rays such as a diffusion plate made of polycarbonate that closes the opening of the backlight unit is suppressed, and the backlight unit The characteristics can be maintained for a long time.

  Here, “absorbing ultraviolet rays of 313 (nm)” means an excitation wavelength spectrum near 254 (nm) (excitation wavelength spectrum means excitation light emission while changing the wavelength of phosphor particles, and the excitation wavelength and emission intensity. The intensity of the excitation wavelength spectrum of 313 (nm) is defined as 80 (%) or more. That is, the phosphor particles that absorb 313 (nm) ultraviolet light are phosphor particles that can absorb 313 (nm) ultraviolet light and convert it into visible light.

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

  In response to such a request, for example, by using the following phosphor particles, the chromaticity range can be expanded as compared with the case of using the phosphor particles in the embodiment. Specifically, in the CIE1931 chromaticity diagram, the chromaticity coordinate value of the phosphor particle for high color reproduction includes a triangle formed by connecting the chromaticity coordinate values of the three phosphor particles used in the embodiment. It is located at the coordinates that expand the color reproduction range.

(A) Blue • Europium activated strontium chloroapatite [Sr ₁₀ (PO ₄ ) ₆ Cl ₂ : Eu ²⁺ ] (abbreviation: SCA), chromaticity coordinates: x = 0.151, y = 0.065
In addition to the above, europium-activated strontium, calcium, barium, chloroapatite [(Sr, Ca, Ba) ₁₀ (PO ₄ ) ₆ Cl ₂ : Eu ²⁺ ] (abbreviation: SBCA) can also be used, and the wavelength 313 (nm) SBAM-B, which can absorb the ultraviolet rays, can also be used for high color reproduction.

(B) Green BAM-G, chromaticity coordinates: x = 0.139, y = 0.574
CMZ, chromaticity coordinates: x = 0.164, y = 0.722
CAT, chromaticity coordinates: x = 0.267, y = 0.663
As described above, these can also absorb ultraviolet rays having a wavelength of 313 (nm), and besides the three phosphor particles described here, MGM can also be used for high color reproduction.

(C) Red • YOS, chromaticity coordinates: x = 0.651, y = 0.344
YPV, chromaticity coordinates: x = 0.658, y = 0.333
MFG, chromaticity coordinates: x = 0.711, y = 0.287
As described above, these can also absorb ultraviolet rays having a wavelength of 313 (nm). Besides the three phosphor particles described here, YVO and YDS can also be used for high color reproduction.

  The chromaticity coordinate values shown above are representative values measured only with the respective phosphor particles, and the chromaticity coordinate values indicated by the respective phosphor particles due to the measurement method (measurement principle) and the like are as described above. The value may be slightly different.

  For reference, the chromaticity coordinate values of the phosphor particles of the above embodiment are YOX (x = 0.644, y = 0.353), LAP (x = 0.351, y = 0.585), BAM- B (x = 0.148, y = 0,056).

  Furthermore, the phosphor particles used for emitting red, green, and blue colors are not limited to one type for each wavelength, and a plurality of types may be used in combination.

  Here, the case where a phosphor layer is formed using the above-described phosphor particles for high color reproduction will be described. The evaluation here is 3 in the case of using phosphor particles for high color reproduction based on the area of NTSC triangle (NTSC triangle) connecting the chromaticity coordinate values of the three primary colors of the NTSC standard in the CIE1931 chromaticity diagram. This is performed by the ratio of the area of a triangle that can connect two chromaticity coordinate values (hereinafter referred to as NTSC ratio).

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

  The chromaticity coordinate values used for the evaluation here are measured in a state where a liquid crystal display device incorporating a lamp or the like is used.

3. Backlight Unit Although the backlight unit in the embodiment is a direct type, it may be an edge type in which a fluorescent lamp is arranged on the edge of the light guide plate.

  Further, as the light source of the direct type backlight unit, a plurality of lamps other than the “U” shape, for example, a straight tube lamp may be used.

  INDUSTRIAL APPLICABILITY The present invention can be used for a fluorescent lamp, a backlight unit, a liquid crystal display device, and a method for manufacturing a fluorescent lamp that can suppress a decrease in luminance with time and further prevent peeling of a phosphor layer.

It is a figure which shows the liquid crystal display device which concerns on invention, and a part is notched so that the mode of an inside may be understood. It is a schematic perspective view of a backlight unit, and a part of the front panel is cut away so that the inside can be seen. (A) is a figure which shows a bending lamp, and has cut out several places of a bending lamp so that the structure of an internal electrode, etc. can be understood. (B) is an enlarged view of the phosphor layer formed on the inner surface of the extending portion of the bent lamp. It is a figure explaining the manufacturing process of a bending lamp. It is a figure explaining the fluorescent substance layer formation process in the manufacturing process of a bending lamp. It is a figure for demonstrating the state change at the time of fluorescent substance layer formation of the binder which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Liquid crystal display device 5 Backlight unit 7 Bending lamp 31 Glass tube 34,36 Bending part 40 Discharge space 51 Phosphor layer 53 Phosphor particle 54 Binder 55 Protective layer 61 Glass tube 63 First suspension 67 Base layer 69 Second suspension

Claims (9)

A phosphor layer is formed on the inner surface of the glass tube having phosphor particles, a binder that connects the phosphor particles, and a protective layer that protects the phosphor particles in a state of being bound by the binder. A fluorescent lamp manufacturing method, comprising:
The phosphor layer is formed by:
A base layer forming step of forming a base layer containing the phosphor particles and the binder by firing;
The suspension containing the organometallic compound for the protective layer is applied to the base layer, dried and then fired to form a protective layer made of a metal oxide, and a protective layer forming step is performed. A method for manufacturing a fluorescent lamp. The method of manufacturing a fluorescent lamp according to claim 1, wherein the organometallic compound contains one or more kinds of metals among yttrium, lanthanum, silicon, magnesium, and zirconium. The method for producing a fluorescent lamp according to claim 1 or 2, wherein the organometallic compound is composed of one or more of metal alkoxide, metal acetylacetonate, and metal carboxylate. In the fluorescent lamp in which the phosphor layer is formed on the inner surface of the glass tube,
The phosphor layer has phosphor particles, a binder that binds the phosphor particles, and a protective layer that protects the phosphor particles;
The binder is directly attached to the phosphor particles,
The protective layer covers the phosphor particles in a portion where the binder is not attached to the phosphor particles, and the phosphor particles together with the binder in a portion where the binder is attached to the phosphor particles. A fluorescent lamp characterized by being coated with The fluorescent lamp according to claim 4, wherein the protective layer is made of a metal oxide. The fluorescent lamp according to claim 5, wherein the metal oxide includes at least one of yttrium, silicon, lanthanum, magnesium, and zirconium as a metal. The binder is composed of one or more of CBB, CBBP, and B ₂ O ₃ , and the content ratio of the binder to the phosphor particles is in a range of 0.5 wt% or more and 3 wt% or less. The fluorescent lamp according to any one of claims 4 to 6, wherein:   A backlight unit comprising the fluorescent lamp according to any one of claims 4 to 7 as a light source.   A liquid crystal display device, wherein the backlight unit according to claim 8 is mounted.

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