JP4059296B2 - Fluorescent lamp, backlight unit and LCD TV - Google Patents

Description

  The present invention relates to a fluorescent lamp, a backlight unit, and a liquid crystal television provided with electrodes at both ends of a tubular glass bulb.

  In recent years, the size of liquid crystal television screens has increased, and the demand for backlight units for large screens has increased. As a lamp used in this backlight unit, for example, a fluorescent lamp having an electrode outside the glass bulb (so-called external electrode type fluorescent lamp) or a fluorescent lamp having an electrode inside the glass bulb (for example, a cold cathode) Type fluorescent lamp) has been put to practical use.

  By the way, in the dark state, these fluorescent lamps are not immediately turned on even when a starting voltage is applied, that is, the dark starting characteristic that it takes a long time to turn on is bad, and the technology for improving this characteristic. For example, an electron-emitting material having a high secondary electron emission coefficient, for example, a cesium compound applied to the inner surface of the end of the glass bulb has been proposed. According to this technique, secondary electrons are emitted from the applied cesium compound, and the secondary electrons are liable to cause a starting discharge, resulting in an improvement in the dark starting characteristics.

As prior art document information related to the invention of this application, for example, Patent Document 1 is known.
JP 2003-36815 A

  However, according to the study by the present inventors, the cesium compound in the vicinity of the light emission region (the region where visible light goes out of the glass bulb) may cause the luminous flux at the time of lamp lighting to be early with time. The problem of decline was revealed.

  That is, cesium is liberated from the cesium compound in the glass bulb in the vicinity of the electrode due to the discharge accompanying the lighting of the lamp. The liberated cesium scatters and adheres to the phosphor layer in the light emission region. Since cesium is yellow and has low translucency, the translucency of the phosphor layer at the cesium adhering portion is also lowered, and as a result, the luminous flux after the lamp is lit is lowered early.

  Further, according to the study by the present inventors, it has been clarified that not only a decrease in luminous flux with time but also a color shift in which the color of the lamp deviates from the design value. In backlight applications, the color misregistration of the lamp leads to the color misregistration of the backlight and adversely affects the color of the display screen of the liquid crystal television.

  The present invention has been made in view of the above problems, and provides a fluorescent lamp, a backlight unit, and a liquid crystal television that have good dark start characteristics and can prevent a decrease in luminous flux and color misregistration over time. It is intended to provide.

In order to achieve the above object, a fluorescent lamp according to the present invention has a mercury bulb and a rare gas in an internal discharge space, and has an inner diameter of 1.0 mm to 3.0 mm, and both ends of the glass bulb. A cold cathode fluorescent lamp in which a phosphor layer comprising phosphor particles is formed on the inner surface of the glass bulb and the glass bulb has a sodium oxide content of 3 wt% In the phosphor particles in the phosphor layer composed of glass in the range of 20 wt% or less, the surface of the alumina-containing phosphor particles containing alumina is larger than the surface of the alumina-free phosphor particles not containing alumina. , has been deposited a metal oxide in a wider area, the end inner surface of the glass bulb, characterized in that a region where the glass bulb is in the uncovered discharge space is present There.

  According to this configuration, the dark start characteristics can be improved by the predetermined amount of sodium oxide contained in the glass bulb. In addition, since the metal oxide adheres to the surface of the alumina-containing phosphor particles containing alumina in a wider area than the surface of the alumina-free phosphor particles not containing alumina, the alumina-containing fluorescence is easily deteriorated. It is possible to effectively suppress mercury adhesion to the body particles, and it is possible to prevent a decrease in luminous flux and color shift over time.

  Further, a protective layer is formed on the inner surface of the glass bulb, and the phosphor layer is formed on the protective layer, and no protective layer is formed on the inner surface of the end portion of the glass bulb. Is characterized in that there is a region exposed to the discharge space.

  According to this configuration, since a predetermined amount of sodium oxide is contained in the glass, sodium oxide exists in the discharge space in the discharge space where the protective layer is not formed. Sodium oxide in this region will be exposed to the discharge space, and the dark starting characteristics can be remarkably improved.

  Further, sodium oxide precipitated from the glass is present in the region.

Further, the protective layer includes at least one of Y ₂ O ₃ , MgO, La ₂ O ₃ , or SiO ₂ .

  The phosphor layer is formed between inner ends of both electrodes, and the protective layer is formed between outer ends of both electrodes.

  Further, the glass bulb is characterized in that the content rate of the sodium oxide is 5 wt% or more and 20 wt% or less.

  Further, the metal oxide is not attached to the surface of the alumina-free phosphor particles, and the metal oxide is attached only to the surface of the alumina-containing phosphor particles.

Further, the metal oxide contains at least one of Y ₂ O ₃ , MgO, La ₂ O ₃ , or SiO ₂ .

  The concentration of the metal oxide with respect to the phosphor in the phosphor layer is 0.1 wt. % Or more.

  In addition, the backlight unit according to the present invention includes the fluorescent lamp as a light source.

  In addition, a liquid crystal television according to the present invention includes the backlight unit.

  The “fluorescent lamp” according to the present invention is a concept including at least a cold cathode fluorescent lamp in which a cold cathode electrode is provided inside a glass bulb.

In addition, “alumina-containing phosphor particles” refers to those containing Al _X O _{Y in the} chemical formula representing phosphor particles, and “alumina-free phosphor particles” refers to Al in the chemical formula representing phosphor particles. _X O _Y is not included.

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

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

  The liquid crystal screen unit 11 includes a color filter substrate, a liquid crystal, a TFT substrate, a drive module and the like (not shown), and forms a color image based on an image signal from the outside.

  The backlight unit 12 is an LCBL unit and includes one high-frequency electronic ballast 13 and 16 dielectric barrier discharge lamps 100 (hereinafter simply referred to as “fluorescent lamps 100”).

  The high-frequency electronic ballast 13 is a lighting circuit that lights all the 16 fluorescent lamps 100.

  Further, the socket base 50 as shown in FIG. 2 holds the both ends of the 16 fluorescent lamps 100 on the electrode socket 51 and the electrode socket 52 made of elastic stainless steel, phosphor bronze or the like, and turns on the lamp. . The width D of the holding portion of the electrode socket 51 and the electrode socket 52 is designed to be a size range that can be held in the region of the external electrodes 102 and 103 described below in order to suppress the occurrence of corona discharge when the lamp is lit. is doing.

  FIG. 3A is a diagram showing an outline of the fluorescent lamp 100 according to Embodiment 1 of the present invention.

  As shown in FIG. 3A, the fluorescent lamp 100 according to the first embodiment of the present invention includes a tubular glass bulb 101.

  Cap-shaped external electrodes 102 and 103 formed of a conductive layer are provided on the outer periphery of both ends of the glass bulb 101.

  Cap-shaped metal members 104 and 105 that cover the external electrodes 102 and 103 are provided on the outer periphery of the external electrodes 102 and 103.

  The material of the metal members 104 and 105 may be any material that has good electrical conductivity and a thermal expansion coefficient close to that of the glass bulb 101. For example, Fe—Ni—Co (Kovar) can be used.

  As shown in part E of FIG. 3A, the external electrodes 102 and 103 are not completely covered with the metal members 104 and 105, but end portions 102a on the glass bulb center side of the external electrodes 102 and 103, 103a (ends 102a and 103a on the opening side of the external electrodes 102 and 103) is exposed.

  A distance L between the end portions 102a and 103a on the glass bulb center side of the external electrodes 102 and 103 and the end portions 104a and 105a on the glass bulb center side of the metal members 104 and 105 is, for example, 1 mm.

  The glass bulb 101 has a substantially circular cross section when cut along a plane perpendicular to the tube axis.

On the inner surface of the glass bulb 101, red (Y ₂ O ₃ : Eu ³⁺ ), green (LaPO ₄ : Ce ³⁺ , Tb ³⁺ ) and blue (BaMg ₂ Al ₁₆ O ₂₇ : Eu ²⁺ ) phosphors The phosphor layer 106 is formed by applying and firing the mixed rare earth phosphor.

  The phosphor layer 106 has a thickness of about 20 μm, and the formation range is between the inner ends of the external electrodes 102 and 103 (a region corresponding to between the inside of the external electrode 102 and the inside of the external electrode 103). .

In the present embodiment, as shown in the F part of FIG. 3A, in the phosphor layer 106, the surface of the blue phosphor particle 106B (BaMg ₂ Al ₁₆ O ₂₇ : Eu ²⁺ ) is oxidized with metal. The product 107 is coated with yttrium oxide (Y ₂ O ₃ ).

  In addition, since there is a step of mixing phosphors of three colors of red, green, and blue in manufacturing, the surrounding red phosphor particles 106R and green fluorescence that the metal oxide coated on the blue phosphor particles 106B comes into contact with. It may adhere to the body particles 106G.

  In addition, the red phosphor particles 106R and the green phosphor particles 106G may be positively coated with a metal oxide.

  The glass bulb 101 is filled with a rare gas 108 such as argon and neon having a pressure of about 8 kPa and about 2 mg of mercury 109. Note that the rare gas 108 as the discharge medium is filled in a reduced pressure state.

  The glass bulb 101 is a discharge envelope, and is made of, for example, soda glass having a sodium oxide content of about 16 wt (%). In this embodiment, the outer diameter is 4.0 mm, the inner diameter is 3.0 mm, and the total length is as follows. It is a 720 mm straight glass bulb.

  FIG. 3B is a diagram illustrating an appearance of the metal member 104.

  The metal member 104 is the same as the metal member 105. The metal member 104 is formed in a shape (cap shape) such that one circular side of a cylindrical shape is covered with a hemispheric dome, and in order to give the metal member 104 an elastic force, for example, in the longitudinal direction. Two slits 110 are provided, and the metal member 104 is connected to the external electrode 102 using the elastic force of the slits 110.

  The metal member 104 is attached from the end portion 101 b of the glass bulb 101. Since the end 104a on the mounting direction side of the metal member 104 is chamfered so as not to have an acute angle portion as shown in part E of FIG. 3A, it can be easily mounted from the end of the glass bulb 101. In addition, the outer peripheral surfaces of the external electrodes 102 and 103 are hardly damaged during mounting and the like.

  The metal members 104 and 105 do not have a fixed shape, such as a metal foil or a metal tape, considering the reduction of damage on the outer peripheral surfaces of the external electrodes 102 and 103, and change shape when force is applied from the outside. Unlike a plastic member that retains its shape even when the force is removed, a non-plastic metal member that has a fixed shape and does not easily change its shape when a force is applied from the outside is preferable.

In the present embodiment, the dimensions of the metal member 104 and the metal member 105 are, for example, a total length of 23.
It is 0 mm, the outer diameter of the cylindrical part is 4.5 mm, the inner diameter is 4.1 mm, the wall thickness is 0.2 mm, and it is not necessary to have plasticity like metal foil or metal tape, so it is set to a thickness that does not cause scratches can do.

  Here, since the outer diameter of the glass bulb 101 is φ4.0 mm, the inner diameter is φ3.0 mm, and the inner diameters of the metal members 104 and 105 are φ4.1 mm, the average clearance between the glass bulb 101 and the metal members 104 and 105 is 0.05 mm. is there.

  The external electrodes 102 and 103 are electrically conductive paste, for example, silver paste at both ends of the sealed glass bulb 101 by a dipping method in advance to a predetermined length from one end of the glass bulb 101, for example, 25.0 mm in total length. It is formed and attached.

  Further, the conductive paste of the external electrodes 102 and 103 is not limited to silver paste, and nickel paste, gold paste, palladium paste, or carbon paste may be used.

Moreover, considering the strong adhesion to the surface of the glass bulb 101 with respect to the conductive paste of the external electrodes 102 and 103, a low melting point glass is preferable as the binder in the conductive paste, and the amount thereof is 1 to 10% by weight. The specific resistance is preferably about 10 ⁻¹ to 10 ⁻⁶ Ω · cm.

In the above embodiment, soda glass containing about 16 (wt%) sodium oxide (Na ₂ O) is used as the glass constituting the glass bulb 101. However, the glass of the present invention contains about about sodium oxide. It is not limited to what contained 16 (wt%).

  In other words, the present invention improves the dark start-up characteristics by depositing sodium oxide contained in the glass constituting the glass bulb 101 and utilizing the deposited sodium oxide. Accordingly, it is sufficient that sodium oxide can be deposited to such an extent that the dark starting characteristics can be improved.

  In consideration of the workability of glass, the content of sodium oxide is preferably in the range of 3 (wt%) to 20 (wt%). When the content of sodium oxide is 5 (wt%) or more, the dark start-up time under dark conditions is about 1 second or less. Conversely, when the content of sodium oxide exceeds 20 (wt%), This is because problems such as whitening of the glass bulb resulting in a decrease in luminance or a reduction in strength of the glass bulb 101 itself occur due to long-term use. In consideration of environmental measures, a glass with a soda glass content of alkali metal within the above range and a lead content of 0.1% or less is preferable (so-called “lead-free glass”). Furthermore, glass having a lead content of 0.01 (%) or less is more preferable.

  The glass is not limited to soda glass. If the sodium oxide content is within the above range, the same effect of improving the dark start-up characteristics can be obtained even if a glass other than soda glass is used.

In the above embodiment, the surface of the blue phosphor particle 106B (BaMg ₂ Al ₁₆ O ₂₇ : Eu ²⁺ ) is described as being coated with yttrium oxide (Y ₂ O ₃ ) as the metal oxide 107. However, the present invention is not limited to this, and any material that includes at least one of Y ₂ O ₃ , MgO, La ₂ O ₃ , or SiO ₂ may be used. However, Y ₂ O ₃ in particular has a characteristic of reflecting ultraviolet rays, and therefore, by reflecting the ultraviolet rays to the inside of the glass bulb, it is possible to increase the efficiency of energy use and to expect an improvement in luminous flux.

  In the above embodiment, the glass bulb 101 has been described as having an outer diameter of 4.0 mm and an inner diameter of 3.0 mm, but the inner diameter of the glass bulb may be larger than 3.0 mm. However, the inner diameter is preferably 3.0 mm or less from the viewpoint of thinning the backlight unit and optimal lamp efficiency. The lower limit is preferably 1.0 mm or more from the viewpoint of manufacturing difficulty.

  In the above-described embodiment, the cross-sectional shape of the glass bulb 101 has been described as a circular shape, but is not limited thereto, and may be an elliptical shape, an oval shape, or the like.

  In the above embodiment, the external electrodes 102 and 103 and the metal members 104 and 105 provided at both ends of the glass bulb 101 are described as caps. However, the present invention is not limited to this. The electrodes 102 and 103 may be formed in a cap shape, and the metal members 104 and 105 may be formed in a punched shape (cylindrical shape with an open bottom surface and an upper surface) that covers the cylindrical portion of the external electrodes 102 and 103.

  Further, in the embodiment, the fluorescent lamp 100 is described as having a straight tube shape, but is not limited thereto, and may have another shape such as a U shape or a W shape.

  Furthermore, in the embodiment, the backlight unit is described as being a direct type as shown in FIG. 1, but the lamp according to the present invention may be used as the light source of the edge type backlight unit.

  Next, functions and effects of the fluorescent lamp 100, the backlight unit 12, and the liquid crystal television 10 of the present invention will be described.

  In the present embodiment, since sodium oxide is contained in soda glass, sodium oxide exists on the surface of glass bulb 101 in the discharge space.

  In particular, sodium oxide in the region in the vicinity of the external electrodes 102 and 103 can improve the dark starting characteristics, and unlike the configuration described in the prior art, this embodiment has a cesium compound in the glass bulb in the vicinity of the electrodes. Therefore, yellowing of the glass due to cesium can be prevented, and a decrease in luminous flux during lamp lighting can be suppressed. Note that a radioactive substance such as cesium may be applied to the inner surfaces of both end portions of the glass bulb 101 which is considered to be less scattered to the light emission region.

  In addition, the metal oxide is adhered in a wider area on the surface of the alumina-containing phosphor particles 106B containing alumina than on the surfaces of the alumina-free phosphor particles 106R and 106G not containing alumina. The metal oxide 107 is attached to a part or all of the surface of the alumina-containing phosphor particles 106B, so that a protective film made of the metal oxide 107 is formed.

  The alumina-containing phosphor particles 106B tend to deteriorate due to the adhesion of mercury, and also tend to deteriorate due to reaction with sodium oxide.

  For this reason, according to the said structure, mercury adhesion to an alumina containing fluorescent substance particle is suppressed effectively, and it can suppress that the light beam at the time of lamp lighting falls. In addition, the reaction between sodium oxide precipitated from soda glass and the alumina-containing phosphor particles 106B can be suppressed, and the reaction causes the alumina-containing phosphor particles 106B to deteriorate, leading to a color shift of the lamp light. Can be prevented.

  In addition, by reducing the amount of metal oxide that is relatively attached to non-alumina-containing phosphor particles that are less likely to deteriorate compared to alumina-containing phosphor particles, it is possible to reduce the lamp beam wastefully due to metal oxide adhesion. Absent.

  Furthermore, it is preferable that 0.1 wt. By containing a metal oxide having a concentration of at least%, it is possible to further prevent color deviation of the lamp light due to the reaction. The reason will be described below.

  4 shows the concentration (wt.%) Of the metal oxide with respect to the phosphor of the phosphor layer 106 on the horizontal axis and the degree of color shift on the vertical axis.

  Here, the color shift refers to the degree of shift from the target value (design value) with respect to the actual value (x1, y1) on the CIE chromaticity coordinates on the CIE chromaticity coordinates (x, y).

Therefore, if the target value on the CIE chromaticity coordinate is (x0, y0), the degree of color shift is (Δx ² + Δy ² ) ^1/2 (where Δx = x0−x1, Δy = y0−y1, It is expressed by.

Then, as a result of examining the direct or indirect visual influence of the light of the lamp due to the color shift, the inventors have determined that the degree of color shift (Δx ² + Δy ² ) ^1/2 exceeds 0.01, It has been found that since the color of the lamp is yellowish, for example, when used as a backlight of a liquid crystal display device, it adversely affects the color reproduction of the liquid crystal display screen and is not preferable.

Based on this knowledge, as apparent from FIG. 4, the concentration of the metal oxide with respect to the phosphor of the phosphor layer 106 is 0.1 wt. %, The degree of color misregistration (Δx ² + Δy ² ) ^1/2 is 0.009, and it is understood that the color misregistration of the lamp light can be prevented at this value.

  However, as apparent from FIG. 4, although the degree of color shift is reduced by increasing the concentration of the metal oxide with respect to the phosphor of the phosphor layer 106, the color shift does not occur even if the concentration exceeds a certain level. The degree hardly changes.

  In addition, as is clear from FIG. 5, it has been found that the relative luminance gradually decreases.

  FIG. 5 shows the concentration (wt.%) Of the metal oxide with respect to the phosphor of the phosphor layer 106 on the horizontal axis and the relative luminance (%) of the lamp on the vertical axis.

  The “lamp relative luminance” here means that the concentration of the metal oxide is 0 wt. The ratio of the initial lighting luminance in a lamp having a certain concentration of the metal oxide when the initial luminance at the initial lighting in the% lamp (for example, when 0 hour lighting has elapsed) is 100% is shown.

  When the relative luminance of the lamp falls below 90%, the lamp light becomes dark. For example, when used as a backlight of a liquid crystal device, the liquid crystal display screen becomes dark, which is not preferable. It was.

  Therefore, as apparent from FIG. By setting the ratio to not more than%, the relative luminance of the lamp can be not less than 90.5%.

  Further, the concentration of the metal oxide is 0.55 wt. If it is%, the relative luminance of the lamp is 96.0%, and the reduction in luminance can be suppressed to an allowable range.

  Note that the concentration of the metal oxide with respect to the phosphor of the phosphor layer 106 is 0.3 to 0.9 wt. By setting the ratio to%, it is possible to further reduce color misregistration and to suppress a decrease in luminance.

  Further, cap-shaped metal members 104 and 105 are provided on the outer periphery of the end portion of the glass bulb 101 so as to surround and connect at least part of the outer peripheral surfaces of the external electrodes 102 and 103 formed of a conductive layer. Since the end portions 104a and 105a of the metal members 104 and 105 on the side are disposed at a distance L from the position of the external electrode ends 102a and 103a on the center side of the glass bulb 101 to the glass bulb end portion 101b side, There are no gaps between the members 104 and 105 and the glass bulb 101 due to variations in installation and mounting of the metal members 104 and 105. As a result, it is possible to suppress the occurrence of corona discharge when the lamp is lit between the metal members 104 and 105 and the glass bulb 101.

  Further, since the metal members 104 and 105 surround the external electrodes 102 and 103 with a length of 3 mm or more, the metal members 104 and 105 at both ends of the fluorescent lamp 100 are the electrode socket 51 and the electrode socket of the socket base 50. 52 is stably connected and can be lit.

  In addition, since the end portions 104a and 105a of the metal members 104 and 105 on the center side of the glass bulb 101 are chamfered, the metal members 104 and 105 can be easily attached from the end portion of the glass bulb 101, and the external portions are attached at the time of attachment. It is possible to make it difficult to damage the outer peripheral surfaces of the electrodes 102 and 103.

  Further, the metal members 104 and 105 have two or more slits 110 formed in the longitudinal direction and connected to the external electrodes 102 and 103 by the elastic force of the metal members 104 and 105, so that The members 104 and 105 can be easily attached, and the outer peripheral surfaces of the external electrodes 102 and 103 can be hardly damaged during the attachment.

  In addition, by using a silver paste for the conductive layers that are the external electrodes 102 and 103, the adhesion to the glass bulb 101 is improved, and the occurrence of corona discharge between the glass bulb 101 and the external electrodes 102 and 103 is suppressed. be able to. In addition, a first capacitor that is equivalently composed of the external electrode 102 and the glass bulb 101 interposed between the external electrode 102 and the discharge space, the external electrode 103, the external electrode 103, and the discharge space It is possible to make the capacitances of both capacitors of the second capacitor equivalently constituted by the glass bulb 101 interposed therebetween substantially equal.

  Further, by including 1 to 10% by weight of low-melting glass as a binder in the conductive paste that is the external electrodes 102 and 103, the metal members 104 and 105 are formed on the outer peripheral surface of the external electrodes 102 and 103 from the end of the glass bulb 101. When the is attached, it is possible to make it difficult to damage the outer peripheral surfaces of the external electrodes 102 and 103.

  Furthermore, although the phosphor particles 106B have been described as being entirely coated (coated) with the metal oxide 107, the coating mode is not limited thereto. For example, a coating mode in which a large number of metal oxide fine particles are attached to the surface of the phosphor particle 106B may be used.

  Moreover, you may use an alumina containing fluorescent substance not only for a blue fluorescent substance particle but for a green fluorescent substance particle.

  FIG. 6 is a diagram schematically showing the phosphor in the phosphor layer, similarly to the F part in FIG.

As the material of the green phosphor particles 1061G, BaMg ₂ Al ₁₆ O ₂₇ : Eu ²⁺ , Mn ²⁺ containing alumina is used, and the alumina-containing phosphor particles 106B and 1061G are coated with a metal oxide. Yes.

(Embodiment 2)
In the first embodiment, the phosphor layer 106 is directly formed on the inner surface of the glass bulb 101. However, the dielectric barrier discharge lamp according to the second embodiment has a protective layer and phosphor on the inner surface of the glass bulb. The layers are formed in this order.

  FIG. 7 is a diagram showing an outline of the dielectric barrier discharge lamp 200 in the second embodiment.

  The lamp 200 shown in FIG. 7 has basically the same configuration as that of the fluorescent lamp 100 in FIG. 3, and members corresponding to members in the 100th order in FIG. To simplify the description.

  The lamp 200 includes a tubular glass bulb 201.

  A protective layer 211 and a phosphor layer 206 are formed in this order on the inner surface of the glass bulb. It can also be said that the phosphor layer 206 is stacked on the protective layer 211.

As the protective layer 211, a layer containing at least one of Y ₂ O ₃ , MgO, La ₂ O ₃ , or SiO ₂ that is a metal oxide can be used.

  By providing the protective layer 211 containing such a metal oxide, it is possible to prevent sodium oxide precipitated from the glass bulb 201 from passing through the phosphor layer 206, and effectively suppress mercury adhesion to the sodium oxide. As a result, it is possible to suppress a decrease in the luminous flux during the lamp lighting.

  Further, the inner surfaces of both end portions 201a and 201b of the glass bulb 201 are regions where the protective layer 211 is not formed. In such a region, since the glass bulb is exposed (exposed) to the discharge space, the effect of improving the dark starting characteristics of sodium oxide, which is the glass bulb material, can be obtained. That is, it is possible to obtain the effect of improving the dark start characteristics while enjoying the effect of the protective layer formation.

  In FIG. 7, the protective layer 211 is formed over a larger area than the phosphor layer 206, but is not limited thereto. That is, the protective layer has a range in which the end face thereof and the end face of the phosphor layer substantially coincide with each other, or a range in which the phosphor layer and the inner surface of the glass bulb do not directly contact each other (by interposing the protective layer, It is only necessary to be formed within a range that can be shielded.

  In particular, in a dielectric barrier discharge lamp, at least the protective layer is an external electrode in the glass bulb, considering pinholes caused by ionized mercury particles jumping into the glass bulb and colliding with the inner peripheral surface of the glass bulb. It is preferable to form over the outer ends (regions corresponding to the outside of one external electrode and the outside of the other external electrode) or to the vicinity of the end face of the glass bulb.

(Modification 1)
The optimum characteristics of the protective film, the shape of the outer surface of the glass bulb, and the like will be described below as Modification 1 according to Embodiment 2.

  FIG. 8 is a diagram showing an outline of the external electrode type fluorescent lamp 400 in the first modification according to the second embodiment.

  Mercury 407 is enclosed in the discharge space 406 of the glass bulb 401 as a luminescent material.

  A protective layer 404 and a phosphor layer 405 are laminated in this order on the inner surface of the glass bulb.

  The external electrodes 402 and 403 are obtained by forming conductive layers 408 and 409 in regions where blast roughening treatment 401 a and 401 b (surface roughness of 1 to 3 μm) is applied to the outer surface of the end portion of the glass bulb 401.

  The conductive layers 408 and 409 have a maximum thickness of 70 μm or less, the end edge portions 408a and 409a are arcuate outward, and the thicknesses become thinner as they approach the edge.

  In the present embodiment, the edge portions 408a, 409a of the conductive layers 408, 409 are positions where W2 exceeds 0.5 mm or more from the region (S) where the rough surface treatment 401a, 401b of the outer surface of the glass bulb 401 is performed. , Preferably 0.5 mm or more and 3 mm or less.

  The conductive layers 408 and 409 are solder materials, for example, mainly composed of tin, an alloy of tin and indium, or an alloy of tin and bismuth, and have a predetermined length from one end of the glass bulb 401. The total length W is 25 mm, the width W1 of the cylindrical portion is about 20 mm, and it is formed over the entire circumference of the glass bulb 401. About the manufacturing method, the solder which melted 25 mm from one end of the sealed glass bulb 401 is immersed in an ultrasonic solder bath, and the thickness of the glass bulb 401 is about 10 μm thick by a known ultrasonic solder dipping. A solder layer is formed.

  Note that the conductive layers 408 and 409 preferably include at least one of antimony, zinc, and aluminum as an additive in the solder material from the viewpoint of adhesion to the glass bulb 401. From the viewpoint of wettability, it is preferable that the solder material contains an additive such as antimony or zinc. Furthermore, considering the environment, it is preferable not to contain an environmentally hazardous substance such as lead.

  Moreover, the reason why W2 is set to 0.5 mm or more and 3 mm or less in the edge portions 408a and 409a of the conductive layers 408 and 409 is based on the following reason.

  If W2 is less than 0.5 mm, it is difficult to form the end edges 408a, 409a of the conductive layers 408, 409 outward in an arc when the ultrasonic solder dipping is used, and the end edges 408a, 409a are angular. This is because corona discharge tends to occur.

  Further, when W2 exceeds 3 mm, there is a problem that the edge portions 408a and 409a of the conductive layers 408 and 409 are easily peeled off from the surface of the glass bulb 401.

The protective film 404 is an yttrium oxide (Y) which is an electron-emitting substance having a maximum thickness of 0.5 μm (surface roughness is 0.2 μm or less) to 2 μm (surface roughness is 1 μm or less) due to an aggregate of metal oxide particles. ₂ O ₃ ), magnesium oxide (MgO) or lanthanum oxide (La ₂ O ₃ ), and in this embodiment, the maximum thickness is obtained by an aggregate of 0.01 to 0.1 μm metal oxide particles. 2μm and surface roughness of the protective film 404 is formed with a Y ₂ O ₃ 1μm.

  That is, when the thickness of the protective film 404 is 2 μm and the surface roughness of the protective film exceeds 1 μm, the luminance is reduced by about 20% compared to the state without the protective film, and the necessary luminance cannot be obtained. When the maximum thickness is less than 0.5 μm and the surface roughness of the protective film 404 exceeds 0.2 μm, the denseness of the protective film is lowered, and the luminance is improved by increasing the drive current to 5 mA or more. In this case, the inventor has a problem that the inner wall of the glass bulb 401 facing the external electrodes 402 and 403 is exposed to the impact of argon ions or mercury ions and is eroded to open a hole (pinhole). It is because it confirmed.

And the area | region where the protective film 404 is not formed exists in the edge part inner surface 401c, 401d of the glass bulb 401, and when the glass bulb 401 end part is sealed, the sodium oxide which precipitated from the glass material exists in this area | region. Can be made.

As a result, since the electron-emitting materials sodium oxide and yttrium oxide are exposed in the discharge space 406, the dark start-up characteristics can be improved.

  The blast roughening of the outer surface of the end portion of the glass bulb 401 and the surface roughness of the protective film 404 are “maximum height Ry” measured in accordance with JIS B 0601: '94.

  Further, the shape of the external electrodes 402 and 403 is not limited to a cap shape, but may be a beak shape (a cylindrical shape with an open bottom surface and an upper surface).

  Further, a cap-shaped metal member that covers the external electrodes 402 and 403 may be provided.

(Modification 2)
The configuration of the external electrode will be described as Modification 2 according to the embodiment. The second modification is basically the same as the external electrode type fluorescent lamp 400 described with reference to FIG. 8 except that the configuration of the external electrodes is different.

  FIG. 9 is a diagram showing an outline of the external electrode type fluorescent lamp 420 in the second modification according to the second embodiment.

  The external electrodes 412 and 413 are cap-shaped, and are formed on the outer surface of the glass bulb 401 in areas where blast roughening treatment 401 a and 401 b (surface roughness of 1 to 3 μm) is performed on the outer surface of the end portion of the glass bulb 401. It is composed of formed electrode body layers 418 and 419 mainly composed of silver or copper, and coating layers 416 and 417 laminated outside the electrode body layers 418 and 419.

  The maximum thickness of the external electrodes 412 and 413 is 70 μm or less, the end edges 412a and 413a of the external electrodes 412 and 413 are arcuate outwards, and the thickness decreases as the edge approaches.

  The electrode body layers 418 and 419 have a maximum thickness d2 of about 7 μm. In the present invention, the thicknesses of the electrode body layers 418 and 419 mean the maximum thickness of the entire electrode body layer. The electrode main body layers 418 and 419 are mainly composed of silver or copper. In addition, the meaning of having silver or copper as a main component includes the case where an alloy of silver and copper is a main component. The main component means that the component is contained most in the composition and has a great influence on the physical properties of the composition. Therefore, compounds other than silver or copper may be included as additives. In order to improve the adhesion of the electrode body layers 418 and 419 to the glass bulb 401, for example, it is conceivable to add glass frit to the electrode body layers 418 and 419. For example, when glass frit containing 1.0 to 5.0 wt% of bismuth (Bi) is added, the adhesion of the electrode body layers 418 and 419 to the glass bulb 401 is improved by the anchor effect of the glass frit. Other additives include ethyl cellulose and the like.

  The electrode body layers 418 and 419 are formed over the entire circumference of the glass bulb 401 with a predetermined length from one end of the glass bulb 401, a total length W of 25 mm, and a cylindrical portion width W1 of about 20 mm. It is. About the manufacturing method, after immersing 24 mm from one end of the sealed glass bulb 401 into a melted silver paste tank by a known dipping method, and applying a silver paste of about 7 μm on the outer peripheral surface of the glass bulb 401, It is formed by firing.

  The coating layers 416 and 417 are laminated on the outer surface of the electrode body layers 418 and 419, and the thickness d3 is about 7 μm. The thickness d3 of the coating layers 416 and 417 means the maximum thickness of the coating layers 416 and 417 as a whole.

  The coating layers 416 and 417 are composed mainly of solder, for example, having a composition of tin: 95.2 wt%, silver: 3.8 wt%, and copper: 1.0 wt%. Since this solder contains silver, it is difficult for the electrode body layers 418 and 419 to be eroded by silver. In addition, in order to make silver erosion hard to occur, it is preferable to make silver content into the range of 1.0-8.0 wt%.

  Regarding the manufacturing method, the coating layers 416 and 417 can be formed by a known dipping method (for example, Japanese Patent Application Laid-Open No. 2004-146351). Briefly, 25 mm from one end of the glass bulb 401 attached to the outer surface of the electrode body layers 418 and 419 is immersed in a molten solder bath, and about 7 μm of solder is applied to the outer surface of the electrode body layers 418 and 419. After coating, it is baked to form.

  Note that the composition of the solder for forming the coating layers 416 and 417 is not limited to the above, and may include, for example, at least one of bismuth, zinc, lead, and the like. However, in order to obtain an environmentally friendly external electrode type discharge lamp, it is preferable that no environmentally hazardous substances such as lead and antimony are contained. The coating layers 416 and 417 may be formed of a material other than solder. For example, a nickel layer formed by electroless plating may be used.

  In general, silver is easily sulfided in the atmosphere, and copper is easily oxidized. When sulfidation or oxidation occurs, silver and copper increase in electrical resistance. Accordingly, when the electrode body layers 418 and 419 are exposed to the atmosphere, the conductivity of the electrode body layers 418 and 419 is lowered. However, in the external electrodes 412, 413 according to the present invention, since the coating layers 416, 417 are laminated outside the electrode body layers 418, 419, the electrode body layers 418, 419 are not easily exposed to the atmosphere. Therefore, silver sulfidation and copper oxidation hardly occur, and the conductivity of the external electrodes 412 and 413 hardly decreases.

  In order to make silver sulfide and copper oxidation difficult to occur, the entire outer surface of the electrode main body layers 418 and 419 is preferably covered with the coating layers 416 and 417. However, a part of the electrode body layers 418 and 419 may be exposed to the atmosphere for production or design reasons as long as the influence on the conductivity of the external electrodes 412 and 413 is small.

  Furthermore, in order to increase the binding force between the electrode body layers 418 and 419 and the coating layers 416 and 417, the outer surface of the electrode body layer on which the coating layers 416 and 417 are laminated is preferably polished.

(Embodiment 3)
In the first and second embodiments, the dielectric barrier discharge lamp has been described as an example of the fluorescent lamp. However, the present invention is not limited to this and can be applied to a cold cathode fluorescent lamp. Hereinafter, the third embodiment will be described.

  FIG. 10 is a diagram showing an outline of the cold cathode fluorescent lamp 300 according to the third embodiment.

  The cold cathode fluorescent lamp 300 has a glass bulb 301 made of soda glass having a straight tube shape. The dimensions of the glass bulb 301 are, for example, a total length of 450 mm, an outer diameter of 3.0 mm, an inner diameter of 2.0 mm, and a wall thickness of 0.5 mm.

  Further, lead wires 314 and 316 are sealed at both ends of the glass bulb 301.

  The lead wire 314 (316) is a connecting wire composed of an internal lead wire 314A (316A) made of tungsten and an external lead wire 314B (316B) made of nickel. Electrodes 302 and 303 are joined to the inner lead wires 314A and 316A on the inner side of the glass container 12 by laser welding or the like, respectively.

  The electrodes 302 and 303 are so-called hollow electrodes having a bottomed cylindrical shape, and niobium is used as a material.

  The glass bulb 301 is filled with a rare gas such as mercury (not shown), argon, neon or the like as a light emitting substance at a predetermined sealing pressure.

  A phosphor layer 306 having a thickness of about 20 μm is formed on the inner surface of the glass bulb 301. The phosphor layer 306 is formed by applying a phosphor suspension on the inner surface of a glass tube, followed by drying and firing processes.

  The phosphor layer 306 is formed by mixing phosphors of red phosphor particles 306R, green phosphor particles 306G, and blue phosphor particles 306B as shown in an enlarged manner in FIG.

The blue phosphor particles 306B are composed of a barium magnesium aluminate europium activated phosphor (BaMg ₂ Al ₁₆ O ₂₇ : Eu ²⁺ ), and are alumina-containing phosphors.

  The surface of the blue phosphor particle 306B is coated with a metal oxide 307 in a layered manner.

(Other)
Each embodiment and the modification can be combined.

  The present invention can provide a fluorescent lamp capable of improving the dark starting characteristics and improving the deterioration of the luminous flux with the passage of time when the lamp is turned on without performing a complicated process. It can be widely applied as an original reading light source used in backlight units, office machines such as copiers, facsimiles, and image scanners, and its industrial utility value is extremely high.

The figure which shows the outline | summary of the liquid crystal television in Embodiment 1 of this invention The figure which shows the outline | summary of the socket stand 50 in the same Embodiment 1. (A) is a figure which shows the outline | summary of the external electrode type fluorescent lamp 100 in Embodiment 1, (b) is a figure which shows the external appearance of the metal member 104. The figure which shows the change of the color shift by the density | concentration of the metal oxide with respect to fluorescent substance The figure which shows the change of the brightness | luminance of a lamp by the density | concentration of the metal oxide with respect to fluorescent substance The figure which shows the fluorescent substance in a fluorescent substance layer typically The figure which shows the outline | summary of the external electrode type fluorescent lamp 200 in Embodiment 2. FIG. The figure which shows the outline | summary of the external electrode type | mold fluorescent lamp 400 in the modification 1 of Embodiment 2. FIG. The figure which shows the outline | summary of the external electrode type | mold fluorescent lamp 420 in the modification 2 of Embodiment 2. FIG. The figure which shows the outline | summary of the cold cathode type fluorescent lamp 300 in Embodiment 3. FIG.

Explanation of symbols

100, 200 Fluorescent lamp 101 Glass bulb 102, 103 External electrode 106 Phosphor layer 106R, 106G Alumina-free phosphor particle 106B Alumina-containing phosphor particle 107 containing alumina 107 Metal oxide 300 Cold cathode fluorescent lamp 302, 303 Electrode

Claims (11)

A glass bulb having mercury and a rare gas in an internal discharge space and having an inner diameter of 1.0 mm to 3.0 mm, electrodes disposed on both ends of the glass bulb, and a phosphor on the inner surface of the glass bulb A cold cathode fluorescent lamp in which a phosphor layer containing particles is formed,
The glass bulb is made of glass having a sodium oxide content of 3 wt% or more and 20 wt% or less,
In the phosphor particles in the phosphor layer, the metal oxide adheres to the surface of the alumina-containing phosphor particles containing alumina in a wider area than the surface of the alumina-free phosphor particles not containing alumina. And
A cold cathode fluorescent lamp characterized in that a region where the glass bulb is exposed to the discharge space exists on the inner surface of the end portion of the glass bulb . A protective layer is formed on the inner surface of the glass bulb, and the phosphor layer is formed on the protective layer,
2. The cold cathode fluorescent lamp according to claim 1, wherein a protective layer is not formed on the inner surface of the end portion of the glass bulb, and there is a region where the glass bulb is exposed to the discharge space. 3. The cold cathode fluorescent lamp according to claim 2, wherein sodium oxide precipitated from the glass is present in the region. The cold cathode fluorescent lamp according to claim 2 or 3, wherein the protective layer contains at least one of Y ₂ O ₃ , MgO, La ₂ O ₃ , or SiO ₂ . The said fluorescent substance layer is formed over the inner end of both electrodes, and the said protective layer is formed over the outer end of both electrodes, The any one of Claims 2-4 characterized by the above-mentioned. Cold cathode fluorescent lamp. The cold cathode fluorescent lamp according to any one of claims 1 to 5, wherein the glass bulb has a content of the sodium oxide of 5 wt% or more and 20 wt% or less. The metal oxide is not attached to the surface of the alumina-free phosphor particles, and the metal oxide is attached only to the surface of the alumina-containing phosphor particles. 6. The cold cathode fluorescent lamp according to any one of 6 above. 8. The metal oxide according to claim 1, wherein at least one of Y ₂ O ₃ , MgO, La ₂ O ₃ , and SiO ₂ is included in the metal oxide. Cold cathode fluorescent lamp. The cold cathode fluorescent lamp according to any one of claims 1 to 8, wherein the concentration of the metal oxide with respect to the phosphor in the phosphor layer is 0.1 wt% or more. A backlight unit comprising the cold cathode fluorescent lamp according to claim 1 as a light source. A liquid crystal television comprising the backlight unit according to claim 10.

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