JP2007134219A - Fluorescent lamp, fluorescent lamp unit equipped with it, and display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fluorescent lamp which prevents an emission luminance from deteriorating and color balance from decreasing while maintaining a predetermined initial emission luminance, and can realize a longer service life; a fluorescent lamp unit equipped with it; and a display device. <P>SOLUTION: A fluorescent lamp 20 has a glass bulb 30 with which mercury is enclosed, and the inside of which is coated with multiple kinds of phosphor particles having different degrees of aging deterioration caused by the mercury from each other. A rare earth oxide for preventing the aging deterioration is adhered to a first phosphor particle in the lowest degree of the aging deterioration by a first predetermined volume, to phosphor particles excepting the first phosphor particle and a second phosphor particle in the highest degree of the aging deterioration by a range from the first predetermined volume to a second predetermined volume larger than the first predetermined volume, and to the second phosphor particle by the second predetermined volume. In addition, the fluorescent lamp unit is equipped with the fluorescent lamp, and the display device is equipped with the fluorescent lamp unit. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fluorescent lamp using a discharge of mercury vapor, a fluorescent lamp unit including the same, and a display device.

A display device such as a liquid crystal display device includes a fluorescent lamp unit connected to a drive circuit. The fluorescent lamp therein has a phosphor layer formed on the inner surface of the lamp vessel, and mercury is sealed inside the vessel. When the mercury is excited and ultraviolet rays are generated and visible light is emitted from the phosphor layer, the unit functions as a light source of the display device.
However, the phosphor layer deteriorates with the use of the fluorescent lamp, and the above-described adsorption of mercury is cited as the cause. Due to this adsorption, it becomes increasingly difficult for the phosphor particles to perform well, and the luminance of the fluorescent lamp is deteriorated, and further the life of the fluorescent lamp is reached.

Therefore, in order to protect the phosphor particles from mercury adsorption, a protective layer is provided on the phosphor layer to reduce the luminance and extend the life. As one of the methods, in order to suppress mercury adsorption and maintain a predetermined emission luminance, as shown in the phosphor particle schematic diagram of FIG. 8, the gaps between the phosphor particles constituting the phosphor layer are cross-linked. It has been proposed to form a protective layer made of a metal oxide that is continuously covered with a structure (for example, Patent Document 1).
JP 2002-164018 A

  However, even when the protective layer according to Patent Document 1 is used, mercury adsorption on the phosphor particles can be suppressed, but mercury adsorption has not been completely prevented, and there is still room for improvement. Has been. Therefore, if a method such as thickening the protective layer is used, the effect of suppressing phosphor particle deterioration is improved by suppressing the adsorption of mercury, but the emission from the phosphor layer is blocked by the thickening. As a result, there is a problem in that the emission luminance is lowered, which is not preferable.

In addition, since the adsorptivity of mercury differs depending on the phosphor particle material, the degree of deterioration with time is greater in phosphor particles that are easily adsorbed with mercury than in other phosphor particles. Color balance is also greatly reduced.
The present invention has been made in view of the above-described problems, and suppresses deterioration of light emission luminance and color balance while maintaining a predetermined initial light emission luminance, and a fluorescent lamp capable of realizing a long lifetime, and An object of the present invention is to provide a fluorescent lamp unit and a display device provided.

In order to solve the above-described problems, a fluorescent lamp, a fluorescent lamp unit including the fluorescent lamp, and a display device according to the present invention have the following configurations.
A fluorescent lamp in which a plurality of types of phosphor particles having different degrees of deterioration due to mercury are coated inside a glass bulb in which mercury is sealed, wherein the rare earth oxide that suppresses deterioration with time is the The first phosphor particles of the type with the smallest degree of degradation are deposited by a first predetermined amount, and the types of the first phosphor particles except for the first phosphor particles and the second phosphor particles of the kind with the greatest degree of deterioration with time. The phosphor particles are deposited in a range not less than the first predetermined amount and not more than a second predetermined amount that is greater than the first predetermined amount, and the second phosphor particles are applied only by the second predetermined amount. It is assumed that it is attached.

Further, in the above-mentioned configuration, the individual particles of the rare earth oxide are formed on the phosphor particles of the type excluding at least the first phosphor particles, and the phosphor particles of all types composed of the plurality of types are applied to the phosphor particles. The entire film of rare earth oxide is formed uniformly.
Further, a phosphor layer is formed of the plurality of types of phosphor particles, and the entire coating covers the entire phosphor layer and fills a space between the plurality of types of phosphor particles. It is preferable that the individual coating film has a configuration in which individual phosphor particles of a type excluding at least the first phosphor particles are individually covered. In addition, the space | gap between each fluorescent substance particle may not be made into the full filling state by the whole film, but the part of each fluorescent substance particle may be in the exposed state.

For example, the individual coating may be formed only on the second phosphor particles, or may be formed on a type of phosphor particles other than the first phosphor particles.
In addition, in the case where the plurality of types of phosphor particles include three types of red phosphor particles that emit red, green, and blue, green phosphor particles, and blue phosphor particles, respectively, The red phosphor particles correspond to the first phosphor particles, and the blue phosphor particles correspond to the second phosphor particles. In the first predetermined amount, the weight composition ratio of the rare earth oxide to the first phosphor particles is set in a range of 0.01 wt% or more and 0.90 wt% or less. The determination is configured such that the weight composition ratio of the rare earth oxide to the second phosphor particles is set to be larger than the first predetermined amount by a range of 0.01 wt% or more and 0.60 wt% or less. It is preferable to do.

The rare earth oxide preferably contains at least one of lanthanum oxide and yttrium oxide.
And the fluorescent lamp unit provided with said fluorescent lamp, Furthermore, the display apparatus provided with the said fluorescent lamp unit is comprised.

  As in the present invention, at least a first predetermined amount is applied to all types of phosphor particles for suppressing rare-time degradation of phosphor particles whose main factor is adsorption of mercury. Thus, the deterioration over time is suppressed, and further, for the second phosphor particles having the largest deterioration over time, a second predetermined amount larger than the first predetermined amount is applied, Even when mercury enters the phosphor layer, it is possible to prevent the second phosphor particles from being significantly deteriorated over time due to mercury adsorption as compared with other types of phosphor particles. As a result, it is possible to suppress the deterioration of the luminance of the fluorescent lamp over time and to suppress the decrease of the color balance, leading to the extension of the life of the fluorescent lamp.

In addition, since the rare earth oxide is applied to all types of phosphor particles according to the degree of deterioration with time, the amount of rare earth oxide applied to the phosphor particles with small deterioration over time Can be kept small, and the initial emission luminance is not greatly reduced.
Further, the rare earth oxide forms an individual coating on at least the types of phosphor particles excluding the first phosphor particles, and the entire coating is uniformly formed on all types of phosphor particles. Therefore, there is no significant difference in the degree of deterioration with time in each phosphor particle, which is preferable from the viewpoint of maintaining color balance.

In particular, the individual coating has a configuration that covers the phosphor particles, so that the effect of suppressing mercury adsorption is improved, and the entire coating covers the phosphor layer and fills between the phosphor particles. By having a network configuration or a network configuration, it is possible to further suppress the adsorption of mercury into the phosphor layer and the intrusion into the phosphor layer.
Plural types of phosphor particles include blue, green and red phosphor particles, the red phosphor particles are less susceptible to deterioration due to mercury adsorption, and the green phosphor particles are affected by mercury adsorption such as LAP. In the case where the individual coating is formed only on the blue phosphor particles that are easily affected by the time-dependent deterioration due to mercury adsorption, when the individual coating is formed of a material that is not easily deteriorated, the decrease in the color balance can be suppressed.

On the other hand, the green phosphor particles may be formed of a material other than the LAP, for example, BAMMn, CATMn, ZnSiO ₄ : Mn, or the like. In this case, it is preferable because the effect of improving the color reproducibility of the fluorescent lamp is produced. However, since it is easily affected by deterioration with time due to mercury adsorption, the individual coating is not limited to blue phosphor particles but also green phosphor particles. Therefore, it is possible to suppress a decrease in color balance while providing the effect of improving the color reproducibility.

Furthermore, by setting the amount of the deposited rare earth oxide relating to each phosphor particle within the range of the weight composition ratio as described in claim 7 above, the above effect can be obtained remarkably. This is desirable because it can be done.
The rare earth oxide material preferably contains at least one of lanthanum oxide and yttrium oxide because the above-described effects can be obtained.

Hereinafter, embodiments according to the present invention will be described with reference to the drawings.
(Embodiment 1)
1-1. Overall Configuration FIG. 1 shows an overview of a display device 101 according to the present embodiment, for example, a liquid crystal television.
The display device 101 shown in the figure is a 32-inch liquid crystal television, for example, and includes a liquid crystal screen unit 103 and a fluorescent lamp unit 1.

The liquid crystal screen unit 103 includes, for example, 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.
A high frequency electronic ballast 107 is disposed at the lower end of the liquid crystal screen unit 103, and the high frequency electronic ballast 107 can turn on all of the plurality of cold cathode fluorescent lamps 20 included in the fluorescent lamp unit 1. Done.
1-2. Configuration of Fluorescent Lamp Unit 1 FIG. 2 is a schematic perspective view showing a configuration of a direct-type fluorescent lamp unit 1 according to the present embodiment. This figure is shown with a part of the front panel 16 cut away so that the internal structure can be seen.

The fluorescent lamp unit 1 includes a plurality of cold cathode fluorescent lamps 20, a box-shaped casing 10 having one main surface opened, and a front panel 16 that covers the casing 10.
The cold cathode fluorescent lamps 20 have a straight tube shape, and a plurality of the cold cathode fluorescent lamps 20 are arranged side by side in the short direction of the housing 10 in a state where the axial core extends horizontally. These cold cathode fluorescent lamps 20 are connected to a drive circuit (not shown), and are lit by this drive circuit. The configuration of the lamp 20 will be described later.

  The housing 10 is made of polyethylene terephthalate (PET) resin, and a reflective surface is formed on the inner surface 11 by depositing a metal such as silver. The opening of the housing 10 is covered with a translucent front panel, and is sealed so that foreign matter such as dust does not enter inside. The casing 10 may be made of a material other than resin, for example, a metal material such as aluminum.

The front panel 16 is formed by laminating a diffusion plate 13, a diffusion sheet 14, and a lens sheet 15.
The diffusion plate 13 and the diffusion sheet 14 scatter and diffuse light emitted from the cold cathode fluorescent lamp 20, and the lens sheet 15 aligns the light in the normal direction of the sheet 15. As a result, the light emitted from the cold cathode fluorescent lamp 20 is uniformly irradiated to the entire front panel 16 in the forward direction.

The material of the diffusion plate 13 is made of polycarbonate (PC) resin. PC resin is excellent in moisture resistance, mechanical strength, heat resistance, and light transmission, and the PC resin plate hardly warps due to moisture absorption, so the screen size is large (for example, 17 inches or more). It is also useful for the use of diffusion plates for LCD TVs.
1-3. Configuration of Cold Cathode Fluorescent Lamp 20 Next, the configuration of the cold cathode fluorescent lamp 20 according to the present embodiment will be described with reference to FIG. FIG. 3 is a partially cutaway perspective view showing a schematic configuration of the cold cathode fluorescent lamp 20.

The cold cathode fluorescent lamp 20 includes a glass bulb 30 in which a phosphor layer 32 is disposed on the inner surface side, a lead wire 21 through a bead glass 23, and an electrode 22 fixed to the tip of the lead wire 21. It is. Note that mercury and a rare gas are sealed inside the glass bulb 30.
The glass bulb 30 has a substantially circular cross section and is made of, for example, borosilicate glass. The glass bulb 30 has a length of 720 mm, an outer diameter of 3 mm, and an inner diameter of 2 mm.

  The lead wire 21 is fixed to the end portion of the glass bulb 30 via a bead glass 23. The lead wire 21 is a joint made of an internal lead wire made of tungsten and an external lead wire made of nickel, for example. The bead glass 23 and the glass bulb 30 are fused, and the bead glass 23 and the lead wire 21 are fixed by frit glass, thereby ensuring the airtightness inside the glass bulb 30. The electrode 22 and the lead wire 21 are fixed using, for example, laser welding.

The electrode 22 is a so-called hollow electrode having a bottomed cylindrical shape. Use of the electrode is effective in suppressing sputtering in the electrode 22 caused by discharge during lamp lighting.
Mercury enclosed in the glass bulb 30 is enclosed at a predetermined ratio to the volume of the glass bulb 30, for example, 0.6 (MG / CC). Similarly, a mixed gas of argon and neon (5% for argon and 95% for neon) is used as the rare gas that is sealed, and sealed at a predetermined sealing pressure, for example, 60 (Torr).
1-4. Configuration of Phosphor Layer 32 As shown in the enlarged view of FIG. 3, the phosphor layer 32 is a combination of blue phosphor particles 32B, green phosphor particles 32G, and red phosphor particles 32R (in the figure, Each written as B, G, R). These convert ultraviolet rays emitted from mercury into blue, green and red, respectively.

As the blue phosphor particles 32B according to the present embodiment, BaMg ₂ Al ₁₆ O ₂₇ : Eu ²⁺ (BAM, europium activated barium magnesium aluminate), and as the green phosphor particles 32G, LaPO ₄ : Tb ³⁺ (LAP, with terbium) Y ₂ O ₃ : Eu ³⁺ (YOX, europium activated yttrium oxide) is used as the active phosphor (lanthanum phosphate) and the red phosphor particles 32R.

As shown in the enlarged view of FIG. 3, the phosphor layer 32 has an entire coating (hereinafter referred to as “first protective film”) 320 that covers the surface and connects the phosphor particles, and blue phosphor particles. An individual coating (hereinafter referred to as “second protective film”) 321B covering the 32B is provided.
The first protective film 320 is made of yttrium oxide Y ₂ O ₃ which is a rare earth oxide that is vitrified and chemically stabilized, covers the surface of the phosphor layer 32, and has gaps between the phosphor particles 32B, 32G, and 32R. It has a network-like or mesh-like configuration so as to be filled. In addition, with this configuration, the phosphor layer 32 is provided so that the inside of the glass bulb 30 and the glass bulb 30 are isolated from each other, so that mercury does not reach the inside of the phosphor layer 30 and even the glass bulb 30. Yes. The first protective film 320 has the above-described configuration, and more specifically, a configuration in which a gap 330 is formed between the phosphor particles 32B, 32G, and 32R as shown in FIG. The film 320 is configured to partially cover the phosphor particles 32B, 32G, and 32R (however, with respect to the blue phosphor particles 32B, a second protective film 321B to be described later is covered). In addition, the 1st protective film 320 is set so that it may become 0.3 wt%, respectively so that the weight composition ratio with respect to the fluorescent substance particle 32B, 32G, 32R may become uniform.

The second protective film 321B is made of lanthanum oxide La ₂ O ₃ (hereinafter referred to as “La”), which is a rare earth oxide, and has a configuration covering the blue phosphor particles 32B. The second protective film 321B covers the surface of the blue phosphor particles 32B, and the weight composition ratio of the second protective film 321B to the blue phosphor particles 32B is set to 0.6 wt%. The first protective film 320 is formed so as to cover the second protective film 321B. In this way, the blue phosphor particles 32B are thicker and thicker than the other phosphor particles 32G and 32R by the amount of the second protective film 321B formed. Yes.

The present inventors have confirmed the presence of these first protective film 320 and second protective film 321B using an analyzer such as SEM (scanning electron microscope) and XMA (X-ray microanalyzer).
1-5. Method for Forming Phosphor Layer 32 Next, a method for forming the phosphor layer 32 will be described. In this method, (A) a phosphor particle material preparation step, (B) a phosphor particle coating step, (C) a metal alkoxide treatment step, and (D) a heat treatment step are sequentially performed.

  First, in the step of preparing the phosphor particle material, a phosphor particle material, for example, a three-wavelength region light emitting type phosphor material is prepared. At this time, the second protective film 321B is formed on the blue phosphor particles 32B. As a method for forming the second protective film 321B, for example, the blue phosphor particles 32B are dispersed in a dispersion medium, and an appropriate amount of a second protective film 321B material such as lanthanum oxide is added to the dispersion. Then, the 2nd protective film 321B can be formed by performing the process of removing a dispersion medium, drying, and baking. Although lanthanum oxide is taken as an example here, it can also be implemented by forming a lanthanum compound on the surface of the blue phosphor particles 32B and then oxidizing it during firing. Needless to say, the present invention can be similarly implemented even when other metal materials are used.

Next, in the application step, the prepared phosphor particle material is applied to the inner surface of the glass bulb 30 and dried to form a phosphor layer. Thereafter, in the metal alkoxide treatment step, a metal alkoxide, for example, yttrium isoproxide, is dissolved in butyl acetate and applied onto the formed phosphor layer, and is dried at about 100 ° C. for about 15 minutes. Decompose. Furthermore, since alcohol is generated as the polymerization reaction of the metal alkoxide proceeds, this alcohol is vaporized and removed. Thereafter, in the heat treatment step, the phosphor layer 32 is appropriately heat-treated (about 500 ° C. for 2 minutes) in a sinter furnace to form the first protective film 320. Since the gas is removed between the phosphor particles and from the phosphor layer 32 by performing the heat treatment step or the like, some holes are formed in the first protective film 320 or the second protective film 321B. Although it is conceivable that each of the phosphor particles is separated from the inside of the glass bulb 30 by the first protective film 320 and the second protective film 321B. In addition, although the said metal alkoxide is used in this embodiment, you may use a metal carboxylate, for example.
1-6. Verification Experiment With respect to the luminance and color balance characteristics of the cold cathode fluorescent lamp 20 including the phosphor layer 32 formed as described above, a verification experiment was performed using the following various fluorescent lamps. Comparative Examples 1 to 3 and Example 1 differ only in the configuration of the phosphor layer, and the other parts are the same (see Table 1).
Comparative Example 1 Cold cathode fluorescent lamp 201 in which the first protective film 320 and the second protective film 321B are not provided on the phosphor layer.
(Comparative example 2) The cold cathode fluorescent lamp 202 in which the first protective film 320 is not provided on the phosphor layer, and the second protective film 321B is provided only on the blue phosphor particles 32B.
(Comparative Example 3) The cold cathode fluorescent lamp 203 provided with the first protective film 320 but not provided with the second protective film 321B on the phosphor layer.
Example 1 The cold cathode fluorescent lamp 20 provided with the first protective film 320 and the second protective film 321B in this embodiment.

１−６−１．初期輝度の検証
先ず、第一保護膜３２０の水銀吸着の抑制効果を考慮した上で、蛍光体層３２からの所定の発光輝度を確保し得る第一保護膜３２０の被膜量について検証を行った。当検証実験では、上記被膜量に対する蛍光ランプの初期発光輝度を測定している。なお、本検証では、上記比較例３のように第一保護膜３２０のみを被覆させており、第二保護膜３２１Ｂは設けていない。その結果を図４に示す。当図は、蛍光体粒子に対する保護膜含有量に対する単位面積当たりの輝度をプロットし、そのプロット点に基く回帰直線を示している。

1-6-1. Verification of Initial Luminance First, in consideration of the effect of suppressing mercury adsorption of the first protective film 320, the coating amount of the first protective film 320 capable of ensuring a predetermined emission luminance from the phosphor layer 32 was verified. . In this verification experiment, the initial light emission luminance of the fluorescent lamp with respect to the coating amount is measured. In this verification, only the first protective film 320 is covered as in the comparative example 3, and the second protective film 321B is not provided. The result is shown in FIG. This figure plots the luminance per unit area against the protective film content with respect to the phosphor particles, and shows a regression line based on the plotted points.

  In FIG. 4, the weight composition ratio of the first protective film 320 to the phosphor particles is 0 wt%, 0.05 wt%, 0.1 wt%, 0.15 wt%, 0.3 wt%, 0.6 wt%, 0.9 wt. Luminance brightness of the fluorescent lamp at%, 1.2 wt%, and 1.8 wt% is shown in the order of point P1 to point P9. With respect to the initial emission luminance, compared to the case where the protective film as in Comparative Example 1 is not provided (point P1), the emission luminance of the same level as the initial emission luminance is obtained if the emission luminance is deteriorated by about 3%. Judged to be maintained. In general, the variation in emission luminance of the cold cathode fluorescent lamp 20 is about ± 7% at the minimum, and the error of the emission luminance meter used for measurement is generally said to be 3 to 5%. Yes. Considering these points, if the emission luminance is reduced to about 3%, it can be determined that the emission luminance is within an allowable range in actual use.

  Based on these contents, if the weight composition ratio is up to about 1.5 wt% from FIG. 4, it corresponds to a state where the emission luminance is reduced by 3%, and the initial emission luminance is maintained at the same level. It can be judged. Among these, as can be seen from FIG. 4, until the weight composition ratio reaches 0.6 wt% (point P6), the emission luminance is kept higher than the point P1 where the first protective film 320 is not provided at all. Therefore, it can be said that setting the weight composition ratio to 0.6 wt% is particularly desirable from the viewpoint of initial light emission luminance.

As described above, when the weight composition ratio is in the range of the points P2 to P6, the initial emission luminance is higher than that of the point P1 (Comparative Example 1) even though the phosphor layer 32 is covered with the first protective layer 320. However, in the case of the point P1 (Comparative Example 1), mercury already enclosed during the production of the cold cathode fluorescent lamp 20 is adsorbed to the phosphor particles 32B, 32G, and 32R, thereby This is probably because the phosphor particles 32B, 32G, and 32R are slightly deteriorated. Therefore, it is clear that even if the content of the first protective film 320 is very small, it contributes to the improvement of the initial emission luminance, and the present inventors have a weight composition ratio of 0.01 wt% with respect to the phosphor particles. However, the result that the initial light emission luminance is about 32000 (cd / m ² ) is obtained, and it seems that there is a similar effect.

Therefore, the weight composition ratio of the first protective film 320 to each of the phosphor particles 32B, 32G, and 32R is preferably 0.01 wt% or more and 1.5 wt% or less, and particularly preferably 0.05 wt% or more and 0.6 wt% or less. .
1-6-2. By the way, regarding the maintenance of the color balance, which is a requirement for extending the life of the cold cathode fluorescent lamp 20, in addition to suppressing the deterioration of the phosphor layer 32, mercury in each phosphor particle 32B, 32G, 32R. It is necessary to reduce the difference in adsorptivity. In particular, when the material according to the present embodiment is used, it is considered that the blue phosphor particles 32B are more easily adsorbed and deteriorated than the other color phosphor particles 32G and 32R.

  Therefore, on the basis of the result obtained in the verification experiment (verification of initial light emission luminance), in addition to the state in which the first protective film 320 is formed as in Example 1, the blue phosphor particles 32B The second protective film 321 </ b> B was covered, and the weight composition ratio of the second protective film 321 </ b> B to the blue phosphor particles was changed to conduct a verification experiment regarding changes in emission luminance maintenance ratio and color balance. The results are shown in Table 2.

表２では、青色蛍光体粒子３２Ｂに第二保護膜３２１Ｂが全く外套されていない状態（０％）での初期発光輝度を基準値として、第二保護膜３２１Ｂの各重量組成比率の場合における相対初期発光輝度率を順に示し、上記基準値に対して３％以上低下していなければ同レベルの初期発光輝度を維持しているものとして「○」、３％以上低下していれば上記「○」が示されている場合と比較して、初期発光輝度に劣化が見受けられるものとして「×」の判定を行っている。また、点灯開始時に対する２０００時間後の発光輝度維持率を示すとともに、色バランスの低下が大きな場合は色シフトの発生可能性の有るものとして「×」、劣化が大きくない場合は色シフトの発生が大きく抑制されているものとして「○」の判定を行っている。なお、当該判定に関しては、色バランス低下の指標として色シフト値を用いており、比較例１のように各蛍光体粒子３２Ｂ、３２Ｇ、３２Ｒに第一保護膜３２０及び第二保護膜３２１Ｂが設けられていない状態での色シフト値は、２０００時間経過後で約０．０２程度であるため、表２に示す第二保護膜３２１Ｂの各値に対する点灯開始から２０００時間経過時点での色シフト値が０．０２より大きければ「×」とし、０．０２以下であれば「○」としている。

In Table 2, relative values in the case of the respective weight composition ratios of the second protective film 321B with reference to the initial emission luminance in a state where the second protective film 321B is not covered on the blue phosphor particles 32B (0%). The initial light emission luminance rate is shown in order, and if it does not decrease by 3% or more with respect to the reference value, it is assumed that the initial light emission luminance of the same level is maintained. Compared with the case where "" is shown, the determination of "x" is made on the assumption that the initial light emission luminance is degraded. In addition, the luminance maintenance ratio after 2000 hours with respect to the start of lighting is shown, and “X” indicates that there is a possibility of color shift when the color balance is greatly lowered, and color shift occurs when the deterioration is not large. Is judged as “○” as being largely suppressed. Regarding the determination, a color shift value is used as an index for decreasing the color balance, and the first protective film 320 and the second protective film 321B are provided on the phosphor particles 32B, 32G, and 32R as in Comparative Example 1. Since the color shift value in a state where it is not applied is about 0.02 after 2000 hours have elapsed, the color shift value at the time when 2000 hours have elapsed from the start of lighting with respect to each value of the second protective film 321B shown in Table 2 Is greater than 0.02, "X", and if less than 0.02, "O".

  Therefore, as is clear from Table 2, it is preferable that the blue phosphor particles 32B are preferentially coated with a rare earth oxide so that the second protective film 321B is covered. Effective in terms of maintenance rate. Further, from the viewpoint of the initial emission luminance rate, the weight composition ratio of the second protective film 321B to the blue phosphor particles 32B is preferably 0.6 wt% or less.

Therefore, if the verification result in the above (1-6-1) is included in the verification result, the following contents are derived.
First, from the viewpoint of initial emission luminance, the weight composition ratio of the first protective film 320 and the second protective film 321B with respect to the phosphor particles 32B, 32G, and 32R is set so as not to exceed 1.5 wt% at the maximum. .

Secondly, from the viewpoint of color balance, the blue phosphor particles 32B are more preferentially suppressed by mercury adsorption than the other color phosphor particles 32G and 32R. Therefore, the blue phosphor particles 32B have a second protective film 321B. Is formed so as to have a weight composition ratio in the range of about 0.01 wt% to 0.60 wt%.
In order to satisfy these simultaneously, considering that the second protective film 321B is formed only on the blue phosphor particles 32B at a weight composition ratio in the above range, each phosphor particle 32B of the first protective film 320 is formed. , 32G, and 32R are set such that the weight composition ratio is in the range of 0.01 wt% to 0.90 wt%, and the second protective film 321B is about 0.01 wt% to only blue phosphor particles. It is preferable to be formed in the range of 0.60 wt%.

Thus, by providing the first protective film 320 and the second protective film 321B on the phosphor layer, it is possible to obtain an effect of suppressing mercury adsorption on the phosphor particles 32B, 32G, and 32R, and at the same time. A decrease in the color balance of the emission color can also be suppressed. In particular, if the weight composition ratio of the first protective film 320 to the phosphor particles 32B, 32G, and 32R is limited to a range of 0.05 to 0.6%, as described in (1-6-1) above, This is desirable because it provides an effect of increasing the initial light emission luminance.
1-6-3. Verification of change in luminance rate Based on the above (1-6-1) and (1-6-2), the first protective film 320 and the second protective film 321B having a weight composition ratio within the above range in the phosphor layer 32. Was compared with other cold cathode fluorescent lamps 201, 202, and 203 (Comparative Examples 1 to 3), and a verification experiment was performed on the emission luminance maintenance rate. . The result is shown in FIG.

  FIG. 5 is a graph showing the light emission luminance ratio maintenance rate, where the initial light emission luminance in Example 1 and Comparative Examples 1 to 3 is 100, and the light emission luminance after 500 hours and 1000 hours have elapsed. Has been created. As is clear from this figure, even in Example 1 alone, the emission luminance maintenance ratio is maintained at 95% or more even after 1000 hours have passed. A cold cathode fluorescent lamp is generally said to have a lifetime of 50,000 to 60,000 hours, and it has already been known that the emission luminance maintenance rate rapidly decreases with time. In other words, if a difference in change in the light emission luminance maintenance rate as shown in FIG. 5 appears at 1000 hours after lighting, it can be easily determined that the difference becomes remarkably large after 50000-60000 hours from the start of light emission. Therefore, there is a great difference in the lifetime of the cold cathode fluorescent lamp between Example 1 and Comparative Examples 1 to 3. As a result, the life of the cold cathode fluorescent lamp 20 can be increased by providing the first protective film 320 and the second protective film 321B within the set range described above as in the first embodiment. It will be.

  In the present embodiment, only the blue phosphor particles 32B are covered with the second protective film 321B. However, as shown in the phosphor particle schematic diagram of FIG. 6, the green phosphor particles 32G and the red phosphor particles 32R. In addition, the second protective films 321G and 321R may be covered. However, for example, the film thickness d1 of the second protective film 321B of the blue phosphor particles 32B is larger than the film thicknesses d2 and d3 of the other second protective films 321G and 321R. Therefore, it is necessary that the weight composition ratio with respect to the blue phosphor particles 32B is set to be relatively large. That is, the weight composition ratio of the second protective film 321B with respect to the blue phosphor particles 32B is 0.01 wt% to 0. 0 than the weight composition ratio of the second protective films 321G and 321R with respect to the phosphor particles 32G and 32R of other colors. It is desirable to increase it by 6 wt%.

  Further, as shown in FIGS. 3 and 6, when the phosphor layer 32 has a configuration in which the phosphor particles 32B, 32G, and 32R are stacked, the phosphor layer 32 is surely the top of the phosphor layer 32 from the viewpoint of suppressing mercury adsorption. It is preferable that the first protective film 320 is reliably coated so as to isolate the gap between the upper layer and each of the phosphor particles 32B, 32G, and 32R. However, the first protective film 320 is in a perforated state in the gap. Even if it is formed, the same effect can be obtained if the first protective film 320 having the effect of suppressing the adsorption of mercury is formed so as to wrap a part of each of the phosphor particles 32B, 32G, and 32R. Applicable. In particular, based on the viewpoint of having an effect of adsorbing mercury and suppressing the decrease in emission luminance, it is considered that the hole portion can also have great effectiveness in that the deterioration in emission luminance can be suppressed.

In addition, the second protective films 321B, 321G, and 321R are covered on all types of phosphor particles 32B, 32G, and 32R, and the same is focused on the blue phosphor particles 32B (second protective film 321B). If formed, the same effect can be obtained even if the first protective film 320 is not formed.
(Embodiment 2)
Next, a cold cathode fluorescent lamp different from the first embodiment will be described. However, the present embodiment is different from the first embodiment only in the configuration of the phosphor layer 42, and the description regarding other parts is omitted.
2-1. Configuration of Phosphor Layer 42 As shown in the schematic schematic diagram of FIG. 7, the phosphor layer 42 according to the present embodiment includes only the first protective film 420, the blue phosphor particles 42B, and the green phosphor particles 42G. Second protective films 421B and 421G are provided.

The first protective film 420 is made of yttrium oxide, and the second protective films 421B and 421G are also made of yttrium oxide.
The phosphor particle material is Sr ₅ (PO ₄ ) ₃ Cl: Eu ²⁺ (SCA) for the blue phosphor particles 42B, and BaMg ₂ Al ₁₆ O ₂₇ : Eu ²⁺ , Mn ²⁺ (SCA) for the green phosphor particles 42G. YVO ₄ : Eu ²⁺ (YVO) is used for BAMMn) and red phosphor particles 42R.

  Of the phosphor particles 32B, 32G, and 32R using the material, the blue phosphor particles 42B and the green phosphor particles 42G are more easily adsorbed with mercury than the red phosphor particles 42R. Therefore, as shown in FIG. 7, the second protective films 421B and 421G are formed preferentially to suppress deterioration with time due to mercury adsorption, and even when compared with the red phosphor particles 42R, the blue phosphor particles 42B. There is no significant difference in the degree of deterioration of the green phosphor particles 42G. Therefore, also in this embodiment, it is possible not only to suppress the deterioration of the initial light emission luminance and the light emission luminance maintenance rate, but also to suppress the color balance with time.

In addition, when using the fluorescent substance particle material which concerns on this embodiment, the effectiveness that the color reproducibility can be improved compared with the said Embodiment 1 is also provided. The material of the phosphor particles 42B, 42G, and 42R is not limited to the above, and other materials can be applied. For example, the blue phosphor particle 42B is BAM, the green phosphor particle 42G is a material other than the LAP used in the first embodiment, for example, CATMn, ZnSiO ₄ : Mn, and the red phosphor particle 42R is YOX, MFG or the like. I do not care.

Further, as in the first embodiment, it is preferable that the weight composition ratio of the first protective film 420 and the second protective films 421B and 421G to the respective phosphor particles is set in the above range. As long as the setting of the range is satisfied, the second protective film may be coated on the red phosphor particles 42R also in the present embodiment. Furthermore, the second protective film is formed on all types of phosphor particles 42B, 42G, and 42R, and the blue phosphor particles 42B and the green phosphor particles 42G mainly satisfy the above-mentioned weight composition ratio as described above. As long as the first protective film 420 is formed, the first protective film 420 may not be formed.
(Other matters)
Regarding the first protective film and the second protective film, different materials are used in the first embodiment and the same materials are used in the second embodiment. However, the present invention is not limited to this, and the first protective film and the second protective film are formed of the same material in the first embodiment. 2 may be made of different materials.

In the above-described embodiment, the direct-type fluorescent lamp unit 1 is used, but an edge method or the like is also applicable. Further, although a cold cathode fluorescent lamp is used, the present invention relates to the structure of the phosphor layer, and the same effect can be obtained even when used for other fluorescent lamps such as a hot cathode fluorescent lamp and an external electrode fluorescent lamp. Since it can be obtained, it is applicable.
Further, although borosilicate glass is used as the glass bulb material, soda lime glass having a melting point lower than that of the glass and easy to form can be applied. In this case, sodium or the like is generated at the time of manufacturing and using the fluorescent lamp, causing luminance deterioration. For example, sodium oxide or sodium is generated from the glass bulb to the inside of the phosphor layer between the phosphor layer and the glass bulb. It is desirable to arrange a suppression film.

  Regarding the manufacturing method, after forming the phosphor layer, the metal compound is applied, but the present invention is not limited to this. For example, the metal compound and the phosphor particle material may be mixed in advance and formed on the inner surface of the glass bulb. . However, in this case, the metal alkoxide treatment step and the heat treatment step in the production method described above are not necessary, and the drying time and temperature setting in the phosphor particle material preparation step must be changed.

  The fluorescent lamp of the present invention is not limited to downsizing or upsizing, and is useful for various types of fluorescent lamps.

It is a notch perspective view of the display apparatus which concerns on embodiment. It is a notch perspective view of the fluorescent lamp unit which concerns on embodiment. It is a notch perspective view of the cold cathode fluorescent lamp which concerns on embodiment. It is a graph which shows the relationship between protective film content which concerns on fluorescent substance particle, and the initial stage light emission luminance of a fluorescent lamp. It is a graph which shows the luminous luminance maintenance factor of the fluorescent lamp concerning this Embodiment 1. It is a schematic diagram of the phosphor particles according to the first embodiment. It is a schematic diagram of the phosphor layer according to the second embodiment. It is a schematic diagram of the fluorescent substance layer in the fluorescent lamp which concerns on the conventional fluorescent lamp.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fluorescent lamp unit 10 Case 13 Diffusion plate 14 Diffusion sheet 15 Lens sheet 16 Front panel 20 Cold cathode fluorescent lamp 21 Lead wire 22 Electrode 23 Bead glass 30 Glass bulb 32 Phosphor layer 101 Liquid crystal television 103 Liquid crystal screen unit 320 First protection Film 321B Second protective film

Claims (10)

A fluorescent lamp in which a plurality of types of phosphor particles with different degrees of deterioration due to mercury are applied inside a glass bulb in which mercury is sealed,
The rare earth oxide that suppresses the deterioration with time,
A first predetermined amount is deposited on the first phosphor particles of the type having the smallest degree of deterioration over time,
Except for the first phosphor particles and the second phosphor particles of the type having the greatest degree of deterioration with time, the phosphor particles of a type that is greater than or equal to the first predetermined amount and greater than the first predetermined amount. (Ii) Deposition within a predetermined range,
The fluorescent lamp, wherein the second predetermined amount is applied to the second phosphor particles. An individual film made of the rare earth oxide is formed on the phosphor particles of the type excluding at least the first phosphor particles,
2. The fluorescent lamp according to claim 1, wherein an entire coating of the rare earth oxide is uniformly formed on all types of phosphor particles composed of the plurality of types. A phosphor layer is formed by the plurality of types of phosphor particles,
The overall coating covers the entire phosphor layer and has a network configuration or a network configuration so as to fill between the plurality of types of phosphor particles,
The fluorescent lamp according to claim 2, wherein the individual coating has a configuration in which phosphor particles of a type excluding at least the first phosphor particles are individually covered. The fluorescent lamp according to claim 3, wherein the individual coating is formed only on the second phosphor particles. The fluorescent lamp according to claim 3, wherein the individual coating is formed on phosphor particles of a type excluding the first phosphor particles. The plurality of types of phosphor particles include three types of red phosphor particles that emit red, green, and blue, green phosphor particles, and blue phosphor particles,
The red phosphor particles correspond to the first phosphor particles;
The fluorescent lamp according to any one of claims 1 to 5, wherein the blue phosphor particles correspond to the second phosphor particles. The first predetermined amount is set such that a weight composition ratio of the rare earth oxide to the first phosphor particles is in a range of 0.01 wt% or more and 0.90 wt% or less,
Furthermore, the second predetermined amount is such that the weight composition ratio of the rare earth oxide to the second phosphor particles is larger than the first predetermined amount by a range of 0.01 wt% to 0.60 wt%. The fluorescent lamp according to claim 6, wherein the fluorescent lamp is set. The fluorescent lamp according to any one of claims 1 to 7, wherein the rare earth oxide includes at least one of lanthanum oxide and yttrium oxide. A fluorescent lamp unit comprising the fluorescent lamp according to claim 1. A display device comprising the fluorescent lamp unit according to claim 9.

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