JP2008037883A - Rare earth phosphovanadate fluorescent substance and fluorescent lamp by using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rare earth phosphovanadate salt fluorescent material excited by ultraviolet light in a good efficiency to emit red-colored light and having a high light-emitting intensity, and further a fluorescent lamp having a high lamp light flux and having a wide red color-reproducing range. <P>SOLUTION: This fluorescent material expressed by general formula: (R<SB>1-a</SB>Eu<SB>a</SB>)MO<SB>4</SB>-bCaO [wherein, R is at least 1 kind of an element selected from Y, Gd; M is at least 1 kind of an element selected from V, P; 0.001≤a≤0.2; and 5×10<SP>-7</SP>≤b≤3×10<SP>-5</SP>] is the rare earth phosphovanadate fluorescent material excited by the ultraviolet light in the high efficiency, emitting red colored light and having the high light-emitting intensity, and the fluorescent lamp by using the same has the high lamp light flux and the wide red color-reproducing range. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a rare earth phosphor vanadate phosphor that is excited efficiently by ultraviolet rays and emits red light, and a fluorescent lamp using the same, and more particularly to a cold cathode fluorescent lamp used for a backlight of a liquid crystal display device.

Conventionally, Y ₂ O ₃ : Eu phosphors are mainly used as phosphors for fluorescent lamps that are excited by ultraviolet rays and emit red light. However, this phosphor has a low emission intensity in the deep red region, and is a laptop personal computer. When used in a cold cathode fluorescent lamp used for a backlight of a liquid crystal display such as a computer, there is a problem that a red color reproduction range is narrow.

As a red phosphor used in a cold cathode fluorescent lamp, JP 2002-184357 A discloses Y (P, V) O ₄ : Eu, 3.5MgO · 0.5MgF ₂ · in addition to Y ₂ O ₃ : Eu. GeO ₂ : Mn, (Sr, Mg) ₃ (PO ₄ ) ₂ : Sn, CaSiO ₃ : Pb, Mn are mentioned, but none of them satisfies both the lamp luminous flux and the color reproduction range.

In particular, when Y (P, V) O ₄ : Eu phosphor is used in a cold cathode fluorescent lamp used in a liquid crystal display device instead of Y ₂ O ₃ : Eu phosphor, Y (P, V) O ₄ : Although the red color reproduction range is expanded by light emission in the deep red region of the Eu phosphor, there is a problem in that the luminous flux of the lamp decreases because the emission intensity is lower than that of the Y ₂ O ₃ : Eu phosphor. .
JP 2002-184357 A

  The present invention has been made to solve such problems. An object of the present invention is to provide a rare earth phosphovanadate phosphor that emits red light efficiently when excited by ultraviolet rays, and further provides a fluorescent lamp with a high lamp luminous flux and a wide red color reproduction range. It is to be.

  In order to achieve the above object, the present inventors have intensively studied. As a result, rare earth phosphor vanadate phosphors having a specific composition have high emission intensity, and fluorescent lamps using this phosphor have high lamp luminous flux. A new red color reproduction range was found and the present invention was completed.

(1) The phosphor of the present invention is characterized in that the general formula is represented by the following formula.
(R _1-a Eu _a ) MO ₄ · bCaO
(However, R is at least one element selected from Y and Gd, M is at least one element selected from V and P, 0.001 ≦ a ≦ 0.2, 5 × 10 ⁻⁷ ≦ b. ≦ 3 × 10 ⁻⁵ )
Even if the a value indicating the amount of Eu as an activator element is smaller than 0.001 or larger than 0.2, the light emission luminance due to ultraviolet excitation is lowered. A particularly preferred range is 0.03 ≦ a ≦ 0.1. Even if the b value indicating the amount of Ca contained in the phosphor is smaller than 5 × 10 ^{−7 or} larger than 3 × 10 ⁻⁵ , the light emission luminance due to ultraviolet excitation is lowered. A more preferable range is 1 × 10 ⁻⁶ ≦ b ≦ 2.5 × 10 ⁻⁵ .

(2) A fluorescent lamp of the present invention includes a light-transmitting airtight container, a phosphor layer formed in the light-transmitting airtight container, a discharge medium sealed in the light-transmitting airtight container, and an electrode. Fluorescent lamp
The phosphor layer includes the rare earth phosphor vanadate phosphor according to claim 1.

(3) In the fluorescent lamp of the present invention, the average particle size of the phosphor is in the range of 5.0 to 12.0 μm, the median particle size is in the range of 6.0 to 20.0 μm, and the dispersity is It is the range of 0.40-1.0, It is a fluorescent lamp as described in (2) characterized by the above-mentioned. Here, the average particle diameter is a value measured using a Fischer sub-sieve sizer (FSSS) by the air permeation method, and indicates the size of primary particles. The median particle diameter is measured by using an electric resistance method Coulter Multisizer II (manufactured by Coulter), and indicates a 50% particle diameter (volume basis). In this case, if the particles are strongly aggregated, it is difficult to disperse them to the primary particles, and the aggregated secondary particles are taken for measurement. The dispersity is a value obtained by dividing the average particle diameter by the median particle diameter, and this is defined as the dispersity. It can be evaluated that the larger the value, the better the dispersibility of the phosphor.

The average particle size of the phosphor used in the present invention is preferably in the range of 5.0 to 12.0 μm, and more preferably in the range of 6.0 to 10.0 μm. If the average particle size is smaller than 5.0 μm, the luminous efficiency is lowered. Conversely, if the average particle size is larger than 12.0 μm, the coating amount of the fluorescent lamp is increased. The median particle size is preferably in the range of 6.0 to 20.0 μm, and more preferably in the range of 7.0 to 15.0 μm. When the median particle size is larger than 20.0 μm, the coating properties are deteriorated. Further, the degree of dispersion is preferably in the range of 0.40 to 1.0, and more preferably in the range of 0.50 to 1.0. If the degree of dispersion is less than 0.40, there are many agglomerated particles, so that the coating properties are deteriorated.

(4) The fluorescent lamp according to any one of (2) to (3), wherein the fluorescent lamp is a cold cathode fluorescent lamp. The cold cathode fluorescent lamp is used as a backlight of a color liquid crystal display, and the tube diameter is as thin as 1 to 4 mm, and it is necessary to select a particle size suitable for the process. The phosphor used in the present invention has a particle size preferable as a red light emitting phosphor for a cold cathode lamp.

  The phosphor of the present invention is a rare earth phosphor vanadate phosphor that is excited efficiently by ultraviolet rays and emits red light and has high emission intensity. By using the phosphor of the present invention, the lamp luminous flux is high and the red color reproduction range is wide. A fluorescent lamp can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the embodiment described below exemplifies a rare earth phosphorus vanadate phosphor for embodying the technical idea of the present invention and a fluorescent lamp using the same, and the present invention is a rare earth phosphor vanadate. The salt phosphor and the fluorescent lamp using the same are not specified as follows.

Here, the manufacturing method of the rare earth phosphorus vanadate phosphor according to one embodiment of the present invention will be described in detail. As the phosphor material, using at least one elemental compound selected from yttrium and gadolinium, a europium compound, at least one elemental compound selected from vanadium and phosphorus, and a calcium compound, for each compound, General formula (R _1-a Eu _a ) MO ₄ .bCaO (where R is at least one element selected from Y and Gd, M is at least one element selected from V and P, 0.001 ≦ a ≦ 0.2, 5 × 10 ⁻⁷ ≦ b ≦ 3 × 10 ⁻⁵ ) and mixed, or these phosphor materials are mixed by adding flux to the raw material mixture Get. After filling this raw material mixture into a crucible, it is put in a furnace and fired at 900-1500 ° C. in air. After cooling, the fired product is wet-dispersed and then separated and dried to obtain the rare earth phosphor vanadate phosphor of the present invention.

  As the phosphor material, an oxide or a compound that becomes an oxide by thermal decomposition is preferably used. For example, a compound which decomposes at a high temperature and becomes an oxide such as carbonate, hydroxide, nitrate, oxalate is preferable. Further, a coprecipitate containing all or part of the elements constituting the phosphor or an oxide obtained by calcining these can be used. For example, as a compound of at least one element selected from yttrium and gadolinium, a europium compound, oxides of these rare earth elements, carbonates, hydroxides, nitrates, oxalates, or the like can be used. As the compound of at least one element selected from vanadium and phosphorus, oxides, hydroxides, and the like of these elements can be used. Moreover, as a flux, an alkaline earth compound, a boron compound, etc. are preferable, and it adds in 0.01-1.0 weight part with respect to 100 weight part of fluorescent substance raw materials. It is preferable to mix the phosphor raw material with a ball mill, a V-type mixer or the like, and then fill the crucible with alumina, quartz, silicon carbide or the like, and fire in air at 900-1500 ° C. for 1-20 hours.

  Next, a cold cathode lamp is produced using the rare earth phosphor vanadate phosphor of the present invention. First, a phosphor and a binder such as calcium pyrophosphate and calcium barium borate are added to a nitrocellulose / butyl acetate solution, and these are mixed and suspended to prepare a phosphor-coated suspension. The obtained phosphor-coated suspension is poured into the inner surface of the glass tube, and then dried by passing warm air through the glass tube, followed by baking, exhausting, attaching a filament, and attaching a base to obtain a cold cathode lamp. Since the phosphor of the present invention has a high emission luminance by 254 nm ultraviolet excitation and a tube diameter of 1 to 4 mm, which is a particle size range suitable for a thin cold cathode lamp, a cold cathode lamp having excellent emission characteristics can be obtained.

Next, the characteristics of the rare earth phosphor vanadate phosphor of the present invention will be described with reference to the drawings. FIG. 1 shows the relationship between the relative luminance (%) due to 254 nm ultraviolet excitation and the a value for the (Y _1-a Eu _a ) VO ₄ · 1.5 × 10 ⁻⁵ CaO phosphor according to the embodiment of the present invention. showed that. Here, the relative luminance was measured using a Hitachi spectrophotometer by irradiating the phosphor with 254 nm ultraviolet rays using a low-pressure mercury lamp manufactured by Hamamatsu Photonics Co., Ltd. (Y _0.95 Eu _0.05 ) The relative value is shown when the emission brightness of the VO ₄ phosphor is 100%. From this figure, it can be seen that the relative luminance increases as the value a increases and gradually decreases when the value a exceeds 0.05. The relative luminance is high in the range of a value of 0.001 ≦ a ≦ 0.2, higher in the range of 0.01 ≦ a ≦ 0.2, and further in the range of 0.03 ≦ a ≦ 0.1. You can see that it is getting higher.

FIG. 2 shows the relationship between the relative luminance (%) by the 254 nm ultraviolet excitation and the b value for the (Y _0.95 Eu _0.05 ) VO ₄ .bCaO phosphor according to the embodiment of the present invention. Here, the relative luminance is measured in the same manner as described above, and indicates a relative value when the emission luminance of the (Y _0.95 Eu _0.05 ) VO ₄ phosphor is 100%. From this figure, it can be seen that the relative luminance increases with an increase in the b value and rapidly decreases when the b value exceeds about 1.5 × 10 ⁻⁵ . In addition, the relative luminance is high in the range of b value 5 × 10 ⁻⁷ ≦ b ≦ 3 × 10 ⁻⁵ , and higher in the range of 1 × 10 ⁻⁶ ≦ b ≦ 2.5 × 10 ⁻⁵ . I understand.

As apparent from FIGS. 1 and 2, in the general formula (R _1−a Eu _a ) MO ₄ · bCaO, the a value is in the range of 0.001 ≦ a ≦ 0.2, and the b value is 5 × 10 5. The phosphor of the present invention in the range of ⁻⁷ ≦ b ≦ 3 × 10 ⁻⁵ has high emission luminance due to ultraviolet excitation, and when used in a fluorescent lamp, a fluorescent lamp having a high lamp luminous flux can be obtained. In addition, since the phosphor of the present invention has a high emission intensity in the deep red region, when used in a cold cathode fluorescent lamp used for a backlight of a liquid crystal display device, the phosphor has a red color more than that of a Y ₂ O ₃ : Eu phosphor. The reproduction range can be widened.

  Examples of the present invention will be described below, but it goes without saying that the present invention is not limited to specific examples.

[Example 1]
<Phosphor>
Y ₂ O ₃ ... 0.475 mol (107.3 g)
Eu ₂ O ₃ ... 0.025 mol (8.80 g)
NH ₄ VO ₃ ... 1.000 mol (117.0 g)
CaCO ₃ ······ 1.5 × 10 ⁻⁵ mol (0.00015 g)
The phosphor raw material is wet-mixed, dried, filled in an alumina crucible, heated from room temperature to 1250 ° C. at 300 ° C./hr in air, and fired at 1250 ° C. for 5 hours. The obtained fired product is ball-milled in water, washed with water, separated, dried, passed through a sieve, and has an average particle size of 7.2 μm, a median particle size of 8.1 μm, and a dispersity of 0.89. The inventive (Y _0.95 Eu _0.05 ) VO ₄ · 1.5 × 10 ⁻⁵ CaO phosphor is obtained. Table 1 shows the composition of the phosphor. This phosphor has an emission peak at 618 nm when excited with UV light at 254 nm, the emission color is red, and the chromaticity coordinate values are x = 0.665 and y = 0.333.

<Red fluorescent lamp>
The red light emitting rare earth phosphor vanadate phosphor thus obtained and the nitrocellulose / butyl acetate binder are sufficiently mixed in a porcelain pot to prepare a phosphor-coated slurry. This is poured into a glass tube having a tube diameter of 3 mm, applied to the inner surface thereof, dried through warm air, and baked at 580 ° C. for 15 minutes to form a fluorescent film. Thereafter, exhaust, electrode mounting, and attachment of a base are performed according to a normal method to obtain a red cold cathode fluorescent lamp. The chromaticity coordinate values of this red fluorescent lamp are x = 0.491, y = 0.321, and the lamp luminous flux is 115 lumens.

<White fluorescent lamp>
Next, the rare earth phosphor vanadate phosphor emitting red light, a BaMgAl ₁₀ O ₁₇ : Eu, Mn green light emitting phosphor, and (Sr, Ca, Ba) ₁₀ (PO ₄ ) ₆ Cl ₂ : Eu blue light emitting fluorescence. The body is mixed in a weight ratio of red: green: blue = 35: 25: 40. This mixed phosphor and nitrocellulose / butyl acetate binder are sufficiently mixed in a porcelain pot to prepare a phosphor coating slurry. This is poured into a glass tube having a tube diameter of 3 mm, applied to the inner surface thereof, dried through warm air, and baked at 580 ° C. for 15 minutes to form a fluorescent film. Then, according to a normal method, exhaust, electrode mounting, and attachment of a base are performed to obtain a white cold cathode fluorescent lamp. The chromaticity coordinate values of this white fluorescent lamp are x = 0.251, y = 0.201, and the lamp luminous flux is 220 lumens.

[Examples 2 to 7]
A phosphor is produced in the same manner as in Example 1 except that the phosphor raw materials are mixed in the proportion of the phosphor composition shown in Table 1.

[Example 8]
A phosphor is produced in the same manner as in Example 1 except that NH ₄ H ₂ PO ₄ is added as a phosphor material and mixed at the ratio of the phosphor composition shown in Table 1.

[Example 9]
A phosphor is produced in the same manner as in Example 1 except that Gd ₂ O ₃ is added as a phosphor material and mixed at the ratio of the phosphor composition shown in Table 1.

[Example 10]
A phosphor is produced in the same manner as in Example 1 except that Gd ₂ O ₃ is used in place of Y ₂ O ₃ as a phosphor material, and mixing is performed at the ratio of the phosphor composition shown in Table 1.

[Comparative Example 1]
(Y _0.95 Eu _0.05 ) VO ₄ phosphor as in Example 1 except that CaCO ₃ is not added as a phosphor raw material and is mixed in the proportion of the phosphor composition shown in Table 1. Is made.

[Comparative Examples 2 to 4]
A phosphor is produced in the same manner as in Example 1 except that the phosphor material is mixed in the proportion of the phosphor composition shown in Table 1.

Table 2 shows the luminance and chromaticity coordinate values of the rare earth phosphovanadate phosphors obtained in Examples 1 to 10 and Comparative Examples 1 to 4 when excited with 254 nm ultraviolet light. The emission luminance shown in this table is relative luminance when the emission luminance of the (Y _0.95 Eu _0.05 ) VO ₄ phosphor of Comparative Example 1 is set to 100%. From Table 2, it can be seen that the phosphors of the examples of the present invention have higher emission luminance due to ultraviolet excitation than the phosphors of the comparative examples. The chromaticity coordinate value of the phosphor of the present invention is such that the x value is in the range of 0.630 ≦ x ≦ 0.690 and the y value is in the range of 0.310 ≦ y ≦ 0.360, and emits red light. I understand that. In the phosphor of the present invention, the chromaticity coordinate value is preferably in the range of x value of 0.650 ≦ x ≦ 0.680, y value of 0.320 ≦ y ≦ 0.350, and x value of 0.00. A range of 650 ≦ x ≦ 0.670 and a range of y value of 0.330 ≦ y ≦ 0.340 are more preferable.

For the cold cathode fluorescent lamps produced in the same manner as in Example 1 using the rare earth phosphor vanadate phosphors obtained in Examples 1 to 10 and Comparative Examples 1 to 4, the chromaticity coordinate values and the lamp luminous flux are shown in Table 3 and Table 3. 4 shows. From the chromaticity coordinate values and the lamp luminous flux values of the red fluorescent lamp shown in Table 3, it can be seen that the fluorescent lamp of the present invention has a higher luminous flux than the fluorescent lamp of the comparative example and the red color reproduction range is expanded. . As for the chromaticity coordinate value of the red fluorescent lamp of the present invention, the x value is preferably in the range of 0.570 ≦ x ≦ 0.600, the y value is preferably in the range of 0.310 ≦ y ≦ 0.330, and the x value is 0.00. A range of 565 ≦ x ≦ 0.595 and a range of y value of 0.315 ≦ y ≦ 0.325 are more preferable. Also, from the data of the white fluorescent lamp shown in Table 4, it can be seen that the fluorescent lamp of the present invention has a higher lamp luminous flux than the fluorescent lamp of the comparative example. Thus, a fluorescent lamp with a wide lamp luminous flux and color reproduction range can be obtained according to the present invention.

  As described above, since the phosphor of the present invention is efficiently excited by ultraviolet rays and emits red light and has high emission intensity, it can be suitably used for general illumination fluorescent lamps, cold cathode fluorescent lamps, and the like. In particular, when used in a cold cathode fluorescent lamp used for a backlight of a liquid crystal display device, a cold cathode fluorescent lamp having a high lamp luminous flux and a wide red color reproduction range can be provided.

It is a figure which shows the relationship between the relative luminance (%) by 254 nm ultraviolet excitation of the fluorescent substance of this invention, and a value. It is a figure which shows the relationship between the relative luminance (%) by 254 nm ultraviolet excitation of the fluorescent substance of this invention, and b value.

Claims (4)

A rare earth phosphor vanadate phosphor characterized by the following general formula:
(R _1-a Eu _a ) MO ₄ · bCaO
(However, R is at least one element selected from Y and Gd, M is at least one element selected from V and P, 0.001 ≦ a ≦ 0.2, 5 × 10 ⁻⁷ ≦ b. ≦ 3 × 10 ⁻⁵ )
  In a fluorescent lamp comprising a translucent airtight container, a phosphor layer formed in the translucent airtight container, a discharge medium enclosed in the translucent airtight container, and an electrode, the phosphor layer is A fluorescent lamp comprising the rare earth phosphor vanadate phosphor according to claim 1.   The average particle size of the phosphor is in the range of 5.0 to 12.0 μm, the median particle size is in the range of 6.0 to 20.0 μm, and the dispersity is in the range of 0.40 to 1.0. The fluorescent lamp according to claim 2, wherein the fluorescent lamp is provided. 4. The fluorescent lamp according to claim 2, wherein the fluorescent lamp is a cold cathode fluorescent lamp.

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