JP2002348571A - Vacuum ultraviolet-excited fluorescent substance and light-emitting device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vacuum ultraviolet-excited fluorescent substance capable of extremely heightening the ultraviolet emission intensity, hardly causing the reduction of the emission intensity when the fluorescent substance is used as a fluorescent substance layer of a light-emitting device such as a plasma display, and hardly causing the deterioration of color characteristics with time, and further to provide the light-emitting device by using the fluorescent substance. SOLUTION: This vacuum ultraviolet-excited fluorescent substance is characterized in that the fluorescent substance comprises a gadorinium-activated rare earth aluminoborate represented by the general formula: (Y1-x Gdx )Al3 (BO3 )4 (0<x<=1).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum ultraviolet-excited ultraviolet phosphor and a light-emitting device using the same, and particularly to a phosphor layer of a light-emitting device such as a plasma display, which can greatly increase the ultraviolet light emission intensity. The present invention relates to a vacuum ultraviolet-excited ultraviolet phosphor which causes less decrease in luminous efficiency and less deterioration with time in chromaticity characteristics when used as a light emitting device, and a light emitting device using the same.

[0002]

2. Description of the Related Art In recent years, a plasma display panel (PDP) has been widely used as a television receiver instead of a conventional large and heavy cathode ray tube (CRT), which has suppressed the stage of commercialization. PDPs are easier to be thinner and lighter than conventional cathode-ray tube type CRTs due to their structural features. Therefore, PDPs have large screens and are required to realize wall-mounted TVs that require further thinning. It is in the spotlight as an opportunity.

FIG. 2 is a cross-sectional view schematically showing a structure of a blue light emitting element portion of a plasma display panel. That is, the plasma display panel 1 has a structure in which a front substrate 2 and a rear substrate 3 having translucency such as glass are arranged to face each other so as to have a predetermined discharge space 10. A large number of blue light emitting element portions 4, green light emitting element portions, and red light emitting element portions corresponding to the three primary colors of BGR are arranged in the direction. Among them, the blue light emitting element section 4
For example, a blue phosphor layer 5 containing phosphor particles is formed on the inner surface of the front substrate 2, while a stripe-shaped positive electrode 6 is formed on the inner surface of the rear substrate 3. And a large number of negative electrodes 7 are arranged. Discharge space 1
The height of 0 is set to about 0.1 mm. In order to generate an ultraviolet ray that excites the phosphor layer 5 upon discharge, the discharge space 10 contains several helium (He) gas or neon (Ne) gas. vol. % Of xenon (Xe) gas.

[0004] The plasma display panel 1 having the above configuration.
As a result, the phosphor layer 5 is excited by vacuum ultraviolet rays (VUV) having a wavelength of 147 nm emitted in the discharge spaces 10 of the electrodes 6 and 7 in resonance with the xenon of the mixed gas 11,
Visible light is emitted and a predetermined image is displayed.

The above plasma display panel (PD)
Regarding P), the improvement of image quality has been the biggest issue in the past, and vigorous improvement aimed at achieving both the brightness representing the brightness of the screen and the contrast ratio, which is the ratio of black and white brightness. Is being promoted. However, at this time, the image quality equivalent to that of a CRT such as a cathode ray tube has not yet been reached.
There is plenty of room for further improvement.

At present, a plasma display panel (PD)
As a light-emitting material for P), a phosphor for general fluorescent lamps and an improved product thereof are used. However, while the fluorescent substance for a fluorescent lamp converts ultraviolet light having a wavelength of 254 nm into visible light, the basic principle of a PDP is to convert ultraviolet light having a wavelength of 147 nm into visible light.
Due to such a difference in the excitation source, a fluorescent material for a fluorescent lamp does not always have excellent characteristics as a fluorescent material for a PDP. However, since there is no use of a phosphor for converting ultraviolet light having a wavelength of 147 nm into visible light other than PDP, development of a new phosphor for PDP having excellent characteristics is currently being delayed.

Conventionally, a plasma display panel (PD)
As the blue light emitting phosphor of P), an aluminate phosphor is widely used. This phosphor has an emission peak wavelength at 450 nm.

On the other hand, as a fluorescent lamp, a lamp in which mercury is sealed in a glass tube as an excitation source of a phosphor layer has been widely used. A fluorescent lamp using a rare gas such as mercury to xenon (Xe) as an excitation source is being developed in parallel.

OA such as a copying machine capable of high-speed copying
Since fluorescent lamps used in equipment are required to have sufficient illuminance characteristics immediately after lighting,
In particular, Xe discharge fluorescent lamps having excellent temperature characteristics are widely used.

Further, in recent years, the demand for fluorescent lamps having a higher light emission intensity by adding a photocatalytic effect has been increasing. This photocatalytic effect is an effect caused by irradiating the titanium oxide applied on the surface of the fluorescent lamp with ultraviolet light generated from the lamp, and can decompose organic substances adsorbed on the surface of the lamp to prevent a decrease in emission luminance. .

Therefore, in order to realize a Xe discharge lamp to which a photocatalytic effect of high efficiency is added, an ultraviolet phosphor which emits ultraviolet light having high intensity with respect to vacuum ultraviolet light emitted from Xe gas is essential. However, in reality, mercury (H
Only phosphors that emit ultraviolet light having a longer wavelength and higher intensity under irradiation of the ultraviolet light emitted by g) are used. As this phosphor, a phosphor having good efficiency has been empirically selected. As a specific example, for example, SrB
₄ O ₇ : Eu, BaSi ₂ O ₅ : Pb, YPO ₄ : Ce
And LaPO ₄ : Ce are used.

[0012]

As described above, a phosphor that emits ultraviolet light having a wavelength longer than that of ultraviolet light when excited by ultraviolet light is SrB ₄ O ₇ : Eu, BaSi ₂ O, as described above.
₅ : Pb, YPO ₄ : Ce, LaPO ₄ : Ce, etc. These phosphors have a wavelength of 25 emitted by mercury.
It is well known that light is emitted by an ultraviolet ray of 3.7 nm, but a vacuum ultraviolet ray (VU) having a wavelength of 200 nm or less is used.
V) It does not have sufficient emission intensity by excitation.
Therefore, among these phosphors, those applied to specific light emitting devices are further limited, and there is a problem that the range of application is narrow.

In any case, it is presently necessary to use the above-mentioned phosphors in the ultraviolet-emitting Xe fluorescent lamp. In order to further increase the luminous intensity, sufficient excitation by vacuum ultraviolet irradiation is required. Achieving a high-intensity ultraviolet phosphor that gives light emission luminance is an important technical issue in realizing a light-emitting device with higher characteristics.

As the demand for light-emitting devices such as a plasma display panel (PDP) and a Xe discharge fluorescent lamp increases, phosphors that efficiently convert vacuum ultraviolet light, which is an excitation source of these light-emitting devices, to visible light can be used. Demand is soaring.

However, vacuum ultraviolet light having a wavelength of 200 nm or less has a very high energy level, and thus has a problem that the main characteristics of the phosphor, such as luminance and chromaticity, deteriorate with time. That is, the fact that the phosphor irradiated with the high-energy vacuum ultraviolet rays is easily deteriorated is inevitable, and it is preferable that a phosphor having excellent resistance to deterioration can be directly synthesized. However, in reality, a phosphor that satisfies characteristics such as luminance and chromaticity and has high resistance to deterioration has not yet been put to practical use.

Attempts to solve the above problems include, for example, JP-A-9-263756 and JP-A-10-208.
No. 647 and Japanese Unexamined Patent Publication No. 11-67103 disclose that phosphor particles which are resistant to deterioration even when irradiated with ultraviolet rays having high energy and emit ultraviolet rays having a wavelength longer than that of vacuum ultraviolet rays are used in conventional phosphor layers. There is disclosed a method of suppressing deterioration of luminance and chromaticity by mixing them. However, the improvement effect is small, and a light emitting device having excellent light emitting characteristics and durability has not yet been realized.

The present invention has been made in order to solve the above-mentioned problems, and particularly, it is possible to greatly increase the intensity of ultraviolet light emission. It is an object of the present invention to provide a vacuum ultraviolet-excited ultraviolet phosphor with a small decrease in efficiency and little deterioration with time of chromaticity characteristics, and a light emitting device using the same.

[0018]

Means for Solving the Problems In order to achieve the above object, the present inventors prepared phosphors having various compositions by blending various elements and compounds, and further prepared those phosphor compositions. A light emitting device such as a PDP having a phosphor layer formed thereon was assembled, and the effects of the type and amount of the added element on the luminous efficiency and deterioration characteristics of the phosphor and the light emitting device were comparatively evaluated by experiments.

As a result, in particular, the phosphor is a rare earth aluminum borate to which gadolinium (Gd) is added in a predetermined amount, and has the general formula (Y _1-x Gd _x ) Al ₃ (BO ₃ ) ₄
When a UV phosphor having a composition of (0 <x ≦ 1) is synthesized, and this phosphor is irradiated with vacuum ultraviolet rays having a wavelength of 200 nm or less, a strong emission peak is obtained at around 311 nm. As a result, it was found that the light emission intensity of the light emitting device having the phosphor layer formed thereon was dramatically increased.

When the conventional blue light-emitting phosphor layer is coated with the ultraviolet phosphor layer formed of the above-mentioned ultraviolet phosphor to form the blue light-emitting element portion of the plasma display panel, the brightness and chromaticity of the plasma display panel are reduced. It has also been found that the deterioration with time of the steel is greatly improved. The present invention has been completed based on the above findings.

That is, the vacuum ultraviolet light emitting device according to the present invention
Is represented by the general formula (Y_1-xGd_x) Al ₃(BO₃)₄(0
Gadolinium-activated rare earth aluminum represented by <x ≦ 1)
It is characterized by being composed of a borate.

Also, the vacuum ultraviolet light emitting device according to the present invention
General formula (Y _1-x Gd _x ) Al ₃ (BO ₃ ) ₄ (0 <x
≦ 1) a phosphor layer containing a gadolinium-activated rare earth aluminum borate and a vacuum ultraviolet ray excited ultraviolet phosphor.

Further, the ultraviolet-emitting fluorescent lamp according to the present invention is a ultraviolet-emitting fluorescent lamp comprising a glass tube filled with a rare gas as an excitation source, and further comprising a phosphor layer adhered to the glass tube. The phosphor layer has the general formula (Y
_1-x Gd _x ) A vacuum ultraviolet-excited ultraviolet phosphor comprising a gadolinium-activated rare earth aluminum borate represented by Al ₃ (BO ₃ ) ₄ (0 <x ≦ 1).

In the above-mentioned ultraviolet light-emitting fluorescent lamp, it is preferable that xenon gas is sealed as a rare gas serving as an excitation source.

In a plasma display panel according to the present invention, the blue light emitting phosphor layer is covered with an ultraviolet phosphor layer in the plasma display panel provided with a blue light emitting element portion having a blue light emitting phosphor layer formed thereon. Features.

In the above plasma display panel, the ultraviolet phosphor layer has a general formula (Y _1-x Gd _x ) Al
It is preferable to contain a gadolinium-activated rare earth aluminum borate represented by ₃ (BO ₃ ) ₄ (0 <x ≦ 1) and a vacuum ultraviolet ray excited ultraviolet phosphor. On the other hand, the blue light-emitting phosphor layer preferably contains a rare earth aluminum borate phosphor activated with europium.

Here, gadolinium (Gd) constituting the ultraviolet phosphor according to the present invention acts as an activator for increasing the luminous efficiency in the blue light emission region by forming a solid solution in the phosphor. Is 0.
Is added and contained in a range exceeding 1 and not more than 1. However, in order to obtain a particularly high emission intensity, the value of x is 0.1
More preferably, it is in the range of 0.75 to 0.75. More preferably, it is in the range of 0.1 to 0.4.

The production method (synthesis method) of the ultraviolet phosphor according to the present invention is not particularly limited, and is produced by blending various phosphor materials as described below in a predetermined component ratio. . That is, a compound capable of easily generating these elements by heat treatment, such as oxides, carbonates, and nitrates of Y, Gd, and Al, and boric acid (H ₃ BO ₃ ) are converted into the compound represented by the general formula (Y _{1 −x} Gd _x ) Al ₃ (BO ₃ ) ₄
Each is weighed and mixed so that (0 <x ≦ 1). Next, the obtained mixture is filled in a crucible, and a temperature of 900 to
Bake at 1100 ° C for 3 to 5 hours. Since the obtained fired product is coagulated, it is pulverized and then washed, dispersed,
By performing washing, drying, and sieving, the ultraviolet phosphor according to the present invention comprising a gadolinium-activated rare earth aluminum borate can be obtained.

The ultraviolet phosphor used in a light emitting device such as a vacuum ultraviolet light emitting element, an ultraviolet light emitting fluorescent lamp, and a plasma display panel according to the present invention is strong around 311 nm when irradiated with vacuum ultraviolet light having a wavelength of 200 nm or less. It has an emission peak. Therefore, in the light emitting device having the phosphor layer formed by using the ultraviolet phosphor according to the present invention, the ultraviolet light emission intensity can be greatly improved when irradiated with vacuum ultraviolet light.

Further, the ultraviolet phosphor according to the present invention, which emits high-intensity ultraviolet rays by irradiating vacuum ultraviolet rays, covers the blue phosphor layer, which has been remarkably deteriorated, so that the luminance and chromaticity of the light emitting device can be improved. Deterioration over time can be effectively suppressed.

The coating method is not particularly limited, and a method in which the suspension of the ultraviolet phosphor of the present invention uniformly dispersed is applied to the surface of the blue phosphor layer to form the ultraviolet phosphor layer integrally. Is enough. At this time, the ultraviolet phosphor layer is formed as a thick film that does not directly irradiate the blue phosphor layer with vacuum ultraviolet rays. Specifically, the thickness is about 5 to 20 μm, although it depends on the particle size distribution of the ultraviolet phosphor particles.

The phosphor constituting the blue phosphor layer is not particularly limited, but may be BaMgAl ₁₀
Preferred is a blue-emitting europium-activated aluminate phosphor such as O ₁₇ : Eu.

In particular, the ultraviolet phosphor of the present invention ((Y _1-x Gd _x ) Al ₃ (BO ₃ ) having a strong emission peak near 311 nm when irradiated with vacuum ultraviolet light having a wavelength of 200 nm.
₄ By coating the blue-emitting europium-activated aluminate phosphor layer with the ultraviolet phosphor layer formed in (0 <x ≦ 1), the luminance and chromaticity of a light-emitting device such as a PDP are significantly deteriorated with time. Can be improved.

That is, if a conventional blue light-emitting phosphor layer is coated with a phosphor which is highly resistant to deterioration even when irradiated with vacuum ultraviolet rays having high energy and emits ultraviolet rays having a wavelength longer than that of vacuum ultraviolet rays, vacuum ultraviolet rays can be applied. Without irradiating the conventional visible light emitting phosphor with light, a light emission mechanism is obtained as if the light were emitted by vacuum ultraviolet irradiation, so that the deterioration of luminance and chromaticity in the vacuum ultraviolet light emitting device is effectively suppressed.

[0035]

Next, an embodiment of the present invention will be described.
This will be described more specifically with reference to the following examples.

Example 1 0.95 mol of Y ₂ O ₃ as a phosphor material and Gd ₂
And 0.05mol of O _3, and 3mol the _Al 2 _{O 3,} H
8 mol of ₃ BO ₃ was weighed and mixed, and the obtained mixture was filled in a crucible and fired in the atmosphere at a temperature of 1000 ° C. for 3 hours. After crushing the obtained fired product, it is further washed with water,
By performing crushing, drying, and sieving, Y _0.95
A gadolinium-activated rare earth aluminum borate phosphor according to Example 1 having a composition of Gd _0.05 Al ₃ (BO ₃ ) ₄ was prepared.

The obtained ultraviolet phosphor was irradiated with vacuum ultraviolet rays (VUV) having a wavelength of 147 nm, and the emission intensity was measured. As a result, an extremely high emission intensity of 780% was obtained.

The emission intensity is the same as that of BaSi of Comparative Example 1, which has been widely used as an ultraviolet phosphor.
The emission peak intensity of the ₂ O ₅ : Pb phosphor was set to a reference value (100
%) As a relative intensity. The same applies to the following embodiments.

Example 2 0.9 mol of Y ₂ O ₃ was used as a phosphor material and Gd ₂ O
₃ and 0.1mol and a 3mol the _Al 2 _{O 3, H} 3 B
The O ₃ were weighed and mixed and 8 mol, the resulting mixture was filled in a crucible and calcined for 3 hours at a temperature 1000 ° C. in air. After pulverizing the obtained calcined product, it is further washed with water, pulverized, dried and sieved to obtain Y _0.9 Gd.
_A gadolinium-activated rare earth aluminum borate phosphor according to Example 2 having a composition of _0.1 Al ₃ (BO ₃ ) ₄ was prepared.

The obtained ultraviolet phosphor was irradiated with vacuum ultraviolet rays (VUV) having a wavelength of 147 nm, and the emission intensity was measured. As a result, an extremely high emission intensity of 1165% was obtained.

Examples 3 to 8 Mixing, sintering, and the like were performed under the same conditions as in Examples 1 and 2, except that the amount of Gd serving as the emission center was changed so as to have the composition ratio shown in Table 1. By carrying out, each ultraviolet phosphor according to Examples 3 to 8 having the composition shown in Table 1 was prepared.

With respect to the ultraviolet phosphors according to the respective Examples and Comparative Example 1 prepared as described above, vacuum ultraviolet rays having a wavelength of 147 nm were irradiated in the same manner as in Example 1, and the emission intensity of the phosphors as powder was measured. . Also, as shown in FIG. 4, a predetermined amount of each of the above-mentioned phosphors is applied to the inner surface of an arc tube (glass bulb) 21 and then dried and fired to form a phosphor layer 22 integrally. After enclosing Xe, bases (electrode sockets) 23 were attached to both ends to prepare a Xe discharge fluorescent lamp, and emission intensity as a lamp characteristic was measured. The measurement results are shown in Table 1 below. Example 5 and Comparative Example 1
FIG. 1 shows the emission spectrum of the ultraviolet phosphor according to the present invention.

[0043]

[Table 1]

As is clear from the results shown in Table 1 and FIG. 1, the emission intensity of the phosphor which emits ultraviolet rays when excited by vacuum ultraviolet rays is shown in Comparative Example 1 of the related art. It has been found that the light emitting device can be drastically increased by 7 to 16 times as compared with the phosphor, and a light emitting device having excellent light emitting characteristics can be obtained.

Embodiment 9 As shown in FIG. 3, a blue phosphor layer 5 made of a europium-activated aluminate phosphor having a composition of BaMgAl ₁₀ O ₁₇ : Eu was provided on a blue light emitting element portion 4a of a plasma display panel 1a. While forming, Y _0.75 Gd _0.25 Al ₃ (B
A light emitting device according to Example 9 was formed by applying a slurry of the gadolinium-activated rare earth aluminum borate phosphor of the present invention having a composition of O ₃ ) ₄ and then drying it to form an ultraviolet light emitting layer 8 having a thickness of 10 μm. Was prepared as a plasma display panel 1a.

Comparative Example 2 The procedure of Example 9 was repeated, except that the ultraviolet light emitting layer 8 comprising the ultraviolet phosphor of the present invention was not formed. 2 was prepared.

In order to evaluate the characteristics of the phosphors of the PDPs of Example 9 and Comparative Example 2 prepared as described above, vacuum ultraviolet rays (VUV) having a wavelength of 147 nm were irradiated to the phosphors and excited. The emission luminance and chromaticity of the obtained emission spectrum were measured. The light emission luminance was measured with the value L ₀ at the time of the initial light emission being 100% (reference value) and the light emission luminance after lighting for 1000 hours as L ₁ , and the ratio of the light emission luminance L ₁ after 1000 hours to the initial value L ₀ was calculated. It was calculated as a luminance maintenance ratio.

The emission chromaticity (x, y) indicates the initial value of the emission, and the change value Δy of the emission chromaticity change is from the chromaticity y ₀ at the time of the initial emission to the chromaticity y after the emission of 1000 hours.
Is a value obtained by subtracting the _1000. The measurement results are shown in Table 2 below.

[0049]

[Table 2]

As is clear from the results shown in Table 2 above, the PDP of Example 9 having the structure in which the conventional blue light-emitting phosphor layer was covered with the ultraviolet phosphor of Example 5 was not covered. Compared with the PDP of Example 2, the luminance maintenance ratio is greatly improved and the chromaticity change value is 1 /
It has decreased to about 5. Therefore, it was found that a light emitting device such as a PDP with less deterioration in luminance and chromaticity of the phosphor can be obtained by using the ultraviolet phosphor of the present embodiment.

It should be noted that the ultraviolet phosphor used in this example is extremely useful because it does not contain a component such as Pb which adversely affects the human body and the environment.

[0052]

As described above, the ultraviolet phosphor according to the present invention has a strong emission peak around 311 nm when irradiated with vacuum ultraviolet rays having a wavelength of 200 nm or less. In the light emitting device having the formed phosphor layer, the intensity of ultraviolet light emission can be greatly improved when irradiated with vacuum ultraviolet light.

Further, the ultraviolet phosphor according to the present invention, which emits high-intensity ultraviolet rays by irradiating vacuum ultraviolet rays, covers the blue phosphor layer, which has conventionally been remarkably deteriorated, so that the luminance and chromaticity of the light emitting device can be improved. Deterioration over time can be effectively suppressed.

[Brief description of the drawings]

FIG. 1 is a graph showing the emission intensity (emission spectrum) of an ultraviolet phosphor according to the present invention in comparison with a conventional example.

FIG. 2 is a cross-sectional view schematically illustrating a structure of a blue light emitting element section of a conventional plasma display panel.

FIG. 3 is a cross-sectional view schematically showing a structure of a blue light emitting element section of the plasma display panel according to the present invention.

FIG. 4 is a front view schematically showing a structure of a fluorescent lamp as a light emitting device according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 1a Plasma display panel (PDP) 2 Front side substrate 3 Back side substrate 4, 4a Blue light emitting element part 5 Blue phosphor layer 6 Positive electrode 7 Negative electrode 10 Discharge space 21 Arc tube (glass bulb) 22 Phosphor layer 23 Base (electrode socket)

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4H001 CA05 CA07 XA05 XA08 XA13 XA39 YA39 YA63 YA64 5C040 FA01 FA02 GB03 GG01 GG03 GG08 MA03 5C043 AA02 CC08 CD01 DD28 DD29 EB04

Claims (7)

[Claims] 1. A method of formula (Y _1-x Gd _x ) Al ₃ (BO
₃ ) A vacuum ultraviolet ray excited ultraviolet phosphor comprising a gadolinium-activated rare earth aluminum borate represented by ₄ (0 <x ≦ 1). 2. A compound of the general formula (Y _1-x Gd _x ) Al ₃ (BO
₃ ) A vacuum ultraviolet light emitting device comprising a phosphor layer containing a vacuum ultraviolet ray excited ultraviolet phosphor made of a gadolinium-activated rare earth aluminum borate represented by ₄ (0 <x ≦ 1). 3. An ultraviolet light-emitting fluorescent lamp having a glass tube filled with a rare gas as an excitation source and further having a phosphor layer adhered to the glass tube, wherein the phosphor layer has the general formula (Y _{1-1). x Gd x) Al 3 (BO} 3) 4 (0 <x ≦
An ultraviolet-emitting fluorescent lamp comprising a vacuum ultraviolet-excited ultraviolet phosphor comprising a gadolinium-activated rare earth aluminum borate represented by 1). 4. The ultraviolet-emitting fluorescent lamp according to claim 3, wherein xenon gas is sealed as the rare gas serving as the excitation source. 5. A plasma display panel comprising a blue light emitting element section having a blue light emitting phosphor layer formed thereon, wherein the blue light emitting phosphor layer is covered with an ultraviolet phosphor layer. 6. The ultraviolet phosphor layer according to the general formula (Y)_1-xG
d_x) Al₃(BO ₃)₄(0 <x ≦ 1)
Gadolinium activated rare earth aluminum borate
An ultraviolet-ray-excited ultraviolet phosphor
The plasma display panel according to claim 5. 7. The plasma display panel according to claim 5, wherein said blue light-emitting phosphor layer contains a rare earth aluminum borate phosphor activated with europium.