KR20070022385A - Display Unit-Use Blue Light Emitting Fluorescent Substance and Production Method Therefor and Field Emission Type Display Unit - Google Patents

Abstract

The blue light emitting phosphor for a display device of the present invention is a zinc phosphor which is excited by an electron beam having an acceleration voltage of 15 kV or less and emits blue light, and a hexagonal zinc sulfide phosphor having silver and aluminum having an average particle diameter of 1.0 to 4.0 μm as an activator It consists of. This blue light emitting phosphor is produced by continuously passing a phosphor raw material through a rotating tubular heating furnace inclined with respect to the horizontal, rapidly heating and firing in the heating furnace, and simultaneously discharging and cooling the fired product. can do. The field emission display device using this blue light emitting phosphor improves display characteristics such as initial luminance (white luminance) and color reproducibility, and has high breakdown voltage characteristics.

Blue light emitting phosphor for display device, hexagonal zinc sulfide phosphor, silver and aluminum activator, field emission display device

Description

Blue Light Emitting Fluorescent Substrate and Production Method Therefor and Field Emission Type Display Unit

The present invention relates to a blue light emitting phosphor for a display device, a method of manufacturing the same, and a field emission display device.

With the advent of the multimedia era, display devices, which are the core devices of digital networks, require large screens, high definition, and correspondence to various sources such as computers.

Among the display devices, field emission display devices (field emission displays; FEDs) using electron emission devices such as field emission cold cathode devices are large screens and thin digital devices capable of displaying various types of information with high precision. Recently, research and development has been actively conducted.

The basic display principle of FED is the same as that of cathode ray tube (CRT), and the phosphor emits and emits light by electron beam, but the acceleration voltage (excitation voltage) of electron beam is 3-15 kV, lower than CRT, and the current density by electron beam Is high. Therefore, it was a reality that sufficient research is not advanced about the fluorescent substance for FED.

In FED, since the acceleration voltage (excitation voltage) is 3-15 kV, which is low compared with CRT, and an electron beam with a high current density is used for excitation, tolerance to the electron beam of a high current density is calculated | required by fluorescent substance. In addition, it is known that the crystal structure of the zinc sulfide phosphor (ZnS: Ag, Al) of blue light emission can be reduced from cubic crystal to hexagonal crystal in order to suppress the deterioration of luminance due to the electron beam impact and increase the lifespan. See, for example, Patent Document 1).

In addition, in order to improve the breakdown voltage characteristics of the FED, it is desirable to improve the surface of the phosphor layer (fluorescent surface) as long as it can achieve flatness or smoothness. In addition, reducing the particle size of the phosphor used to improve the smoothness of the fluorescent surface has been studied.

However, in order to obtain a hexagonal zinc sulfide phosphor, baking at high temperature is required compared to cubic zinc sulfide, so that the average particle diameter is 5 µm or more when baking for a predetermined time by a conventional method to obtain sufficient brightness. This causes a problem that a phosphor having a small particle diameter cannot be obtained.

Patent Document 1: Japanese Unexamined Patent Publication No. 2002-226847 (Second page to third page)

SUMMARY OF THE INVENTION The present invention has been made to solve this problem, and in the blue light emitting phosphor having an acceleration voltage of 15 kV or less used in a field emission display device (FED) or the like and excited by an electron beam of high current density, the light emission luminance is increased to a high level. It aims at realizing color purity and improving smoothness of a fluorescent surface. Moreover, it aims at providing the FED which is excellent in display characteristics, such as high brightness and color reproducibility, and excellent in pressure resistance characteristics by using such a blue light emitting fluorescent substance.

The blue light emitting phosphor for a display device of the present invention includes a hexagonal zinc sulfide phosphor containing silver and aluminum as an activator, and is a phosphor that is excited by an electron beam having an acceleration voltage of 15 kV or less and emits blue light. The silver and aluminum-activated zinc sulfide phosphor of is characterized in that the average particle diameter is 1.0 to 4.0 ㎛.

The manufacturing method of the blue light emitting fluorescent substance for display apparatuses of this invention is a manufacturing method of the said blue light emitting fluorescent substance, Comprising: The fluorescent substance raw material containing the element which comprises a fluorescent substance matrix and an activating agent, or the compound containing the said element is baked and baked. In the firing step, the phosphor raw material is continuously passed through a rotating tubular heating furnace disposed to be inclined with respect to the horizontal, and heated in the heating furnace and calcined, and discharged continuously from the heating furnace. It is characterized by cooling the fired material.

The field emission display device according to the present invention comprises a phosphor layer including a blue light emitting phosphor layer, a green light emitting phosphor layer and a red light emitting phosphor layer, and an electron emission source for emitting light by irradiating the phosphor layer with an electron beam having an acceleration voltage of 15 kV or less. And an envelope for vacuum sealing the electron emission source and the phosphor layer together, wherein the blue light emitting phosphor layer comprises the above-mentioned blue light emitting phosphor for a display device.

Since the blue light-emitting phosphor of the present invention is composed of hexagonal silver and aluminum-activated zinc sulfide phosphors having an average particle diameter of 1.0 to 4.0 µm, the emission luminance when excited by an electron beam having an acceleration voltage of 15 kV or less is obtained. It is compared with the hexagonal silver and aluminum activating zinc sulfide fluorescent substance of large particle diameter. In addition, the color purity is good and has a long service life. In addition, according to the blue phosphor, since the surface of the phosphor having high smoothness and flatness can be obtained, the breakdown voltage characteristics of a thin flat display device such as FED can be significantly improved.

Further, according to the manufacturing method of the present invention, since the phosphor raw material is continuously inclined with respect to the horizontal and passes continuously through the tubular heating furnace rotating around the axis, it is rapidly heated while being driven in the process of moving in the heating furnace. Uniform thermal energy is efficiently applied to the phosphor raw material. As a result, baking can be completed in a short time compared with the baking method using the conventional crucible. Thus, a hexagonal zinc sulfide phosphor having a small particle diameter can be obtained without causing a decrease in luminance.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows typically the structure of the baking apparatus used for embodiment of this invention.

2 is a cross-sectional view schematically showing an FED that is an embodiment of the present invention.

Best Mode for Carrying Out the Invention

Next, preferable embodiment of this invention is described. In addition, this invention is not limited to the following embodiment.

The blue light emitting phosphor according to the first embodiment of the present invention comprises a hexagonal silver and aluminum-activated zinc sulfide phosphor represented by the formula ZnS: Ag, Al, and is 1.0 to 4.0 µm, more preferably 2.0. Have an average particle diameter d of from 3.0 μm. In addition, this average particle diameter d shall represent the value measured by the permeation method (specifically, the Blaine method).

The average particle diameter d of the silver and aluminum-activated zinc sulfide phosphors is limited to 1.0 μm or more because it is difficult to industrially manufacture phosphors having an average particle diameter of less than 1.0 μm and having sufficient luminance. It is also not preferable that the average particle diameter d exceed 4.0 µm because the effect of improving the luminescence brightness is insufficient.

In addition, in the silver and aluminum-activated zinc sulfide phosphors (ZnS: Ag, Al) of this embodiment, the molar ratio (S / Zn) of sulfur atoms and zinc atoms measured by X-ray photoelectron spectroscopy (XPS) is more than 0.97 and not more than 1.0 It is.

Moreover, XPS is a method of irradiating the state (for example, composition of an element) of a solid surface by measuring the kinetic energy of the electron which protrudes by monochromatic light (X-ray) irradiation. Therefore, in the blue light emitting phosphor of the first embodiment, it means that the molar ratio of S / Zn on the surface of the ZnS: Ag, Al phosphor particles is larger than 0.97. In this regard, conventional hexagonal ZnS: Ag, Al phosphors have an average particle diameter d exceeding 4.0 µm (for example, 5 µm or more). In addition, in the conventional hexagonal ZnS: Ag, Al phosphor, the value of S / Zn measured by XPS is 0.97 at maximum, which is far from the stoichiometric molar ratio of 1.

The blue light emitting phosphor of this embodiment is preferable as an electron beam excitation phosphor having an acceleration voltage of 15 kV or less. Specifically, it is preferable as a blue light-emitting phosphor of a high voltage FED having an excitation voltage of 5 kV to 15 kV and a low voltage FED having an excitation voltage of less than 5 kV.

In the hexagonal silver and aluminum-activated zinc sulfide phosphors (ZnS: Ag, Al), Ag is the first activator (main activator) forming the luminescence center and with respect to 1 g of zinc sulfide, the phosphor matrix It is preferable to make it contain in the range of 1 * 10 <^-5> -1 * 10 <^-3> g. Even if the content of Ag as the first activating agent is less than 1 × 10 ⁻⁵ g or more than 1 × 10 ⁻³ g with respect to 1 g of zinc sulfide, the luminescence brightness and the luminescence chromaticity are lowered. The content of Ag is more preferably in the range of 3 × 10 ^-5 to 8 × 10 ^-4 g with respect to 1 g of zinc sulfide, and more preferably in the range of 5 × 10 ^-5 to 5 × 10 ^-4 g. Do.

Al is a second activator (co-activator) that is directly excited by an electron beam, and the zinc sulfide phosphor (ZnS :) emits light by emitting the first activator with the excitation energy of this second activator. Emission luminance of the Ag phosphor) can be increased. The content of Al, which is the second activator, is preferably in the range of 1 × 10 ⁻⁵ to 5 × 10 ⁻³ g with respect to 1 g of zinc sulfide as the phosphor matrix. When the content of Al is less than 1 × 10 ⁻⁵ g or more than 5 × 10 ⁻³ g with respect to 1 g of zinc sulfide, the luminescence brightness is lowered or the luminescence chromaticity is also degraded. The content of Al is more preferably in the range of 3 × 10 ^-5 to 3 × 10 ^-3 g, more preferably in the range of 5 × 10 ^-5 to 1 × 10 ^-3 g with respect to 1 g of zinc sulfide. Do.

Since the zinc sulfide phosphor having a hexagonal crystal structure is excellent in deterioration resistance, even when repeatedly irradiating an electron beam of high current density, deterioration in luminance and the like due to the irradiation impact of the electron beam is suppressed. In order to obtain the effect of suppressing luminance deterioration due to electron beam impact, the ratio of hexagonal crystals in the crystal structure of zinc sulfide is preferably made 50% or more. If the ratio of the hexagonal crystal is less than 50%, the impact resistance against the electron beam cannot be obtained satisfactorily. It is preferable that the ratio of hexagonal crystal in a crystal structure is 80% or more, More preferably, it is 95% or more, It is preferable to make substantially all crystal structures especially hexagonal crystal.

A hexagonal silver and aluminum-activated zinc sulfide phosphor having an average particle diameter d of 1.0 to 4.0 µm which is the first embodiment of the present invention is produced by the method shown below.

First, a predetermined amount of an activator raw material is added to the zinc sulfide raw material which is the phosphor matrix, and fluxes such as potassium chloride and magnesium chloride are added as necessary, and these are mixed in a wet manner. Specifically, the phosphor raw material is dispersed in ion-exchanged water to form a slurry, and any amount of an activator raw material and a flux are added thereto, followed by stirring and mixing by a stirrer. The mixing time is set such that the activator is sufficiently dispersed. Subsequently, the slurry containing the phosphor raw material, the activator, and the like are transferred to a drying container, and dried in a drier to obtain a phosphor raw material.

Next, the obtained phosphor raw material is heated and baked. In the firing step, the phosphor raw material is continuously passed through a rotating tubular heating furnace inclined with respect to the horizontal direction. Further, the phosphor raw material is rapidly heated in a heating furnace to a predetermined firing temperature, and the inside of the furnace is moved from the upper side to the lower side while being driven by the rotation of the heating furnace. In this way, the phosphor raw material is heated for a sufficient time while firing. Thereafter, the fired product is continuously discharged from the heating furnace, and the discharged fired product is rapidly cooled.

In the manufacturing method of this embodiment, it is preferable that oxygen is removed and it is maintained in the oxygen-free state in the tubular heating furnace and the part which cools the burned material discharged | emitted from the heating furnace. In particular, it is preferable to maintain the inside of the furnace in an inert gas atmosphere such as argon or nitrogen, a reducing gas atmosphere containing hydrogen, or even a hydrogen sulfide atmosphere.

In addition, it is preferable that the phosphor raw material is heated and calcined in an oxygen-free atmosphere and quenched in a state in which an oxygen-free atmosphere is maintained. Moreover, it is preferable that the rotational speed of a heating furnace shall be 0.5-50 rotation / min. When the rotational speed exceeds 50 revolutions per minute, it is difficult to control the required firing time, which is not preferable.

Moreover, it is preferable to adjust the inclination angle with respect to the horizontal of a heating furnace according to the length, rotational speed, etc. of a heating furnace, and to make phosphor raw material stay in a furnace for the time enough for baking.

Such a baking process can be performed using the baking apparatus shown in FIG. 1, for example. In Fig. 1, reference numeral 1 denotes a cylindrical tube-shaped heat resistant container containing quartz, alumina, or the like. This heat resistant container 1 is arranged inclined with respect to the horizontal, and is comprised so that it may rotate continuously about a central axis by the rotating mechanism 2, such as a motor. The inclination angle with respect to the horizontal of the heat resistant container 1 is comprised so that adjustment can be carried out according to the length, rotational speed, etc. of a heating part so that fluorescent substance raw material may remain in the heating part mentioned later by time sufficient for baking.

In most of the outer peripheral portion of the heat resistant container 1 in the longitudinal direction, a heating element 3 such as molybdenum silicide is provided, and a heating portion 4 is formed. In addition, the upper part and the lower part of the heat resistant container 1 in which the heat generating body 3 is not provided in the outer peripheral part are cooling parts 5a and 5b. Cooling is mainly performed by water cooling.

An upper end of the heat resistant container 1 is provided with a feeding mechanism (feeder) 6 for continuously transferring phosphor raw materials to be heated and fired, and fired at the lower end of the heat resistant container 1 constituting the cooling part 5b. A fired material collector 7 which receives water continuously is provided.

Moreover, gas, such as an inert gas, is conveyed from the gas introduction port 8 attached to the delivery mechanism 6 so that the whole inside of an apparatus may be an oxygen free state, and the inside of the heat resistant container 1 flows with a baking material. This gas is also discharged from the gas outlet 9 attached to the fired matter collector 7. At this time, the fired material is configured to be completely cooled in the cooling unit 5b.

According to this embodiment, the phosphor raw material is continuously passed through a tubular heating furnace which is disposed inclined with respect to the horizontal and rotates about an axis, and is rapidly heated while being electrically driven in the process of moving in the heating furnace, thereby anoxic state Uniform thermal energy is applied to the phosphor raw material in an inert gas, reducing gas atmosphere or hydrogen sulfide atmosphere. As a result, baking can be completed in a short time compared with the baking method using the conventional crucible. Therefore, a hexagonal zinc sulfide phosphor having a small particle diameter (for example, an average particle diameter d of 1.0 to 4.0 µm) can be obtained without causing a decrease in luminance.

In addition, since aggregation of the phosphor particles can be suppressed, there is no need to further grind after firing. Therefore, since deterioration of the phosphor due to the pulverization step can be suppressed, it is not necessary to add a step such as reannealing, and the process can be reduced. In addition, since the phosphor raw material is heated and fired while rolling the inside of the heating furnace, phosphor particles having a uniform particle size in a shape close to a spherical shape can be obtained.

In addition, since the hexagonal silver and aluminum-activated zinc sulfide phosphors produced by these embodiments have a small diameter of 1.0 to 4.0 µm in average diameter, the luminescence brightness is high when they are excited by an electron beam having an acceleration voltage of 15 kV or less. And also has good color purity. Moreover, it is excellent in the tolerance to the electron beam of a high current density, and the lifetime is improved. In addition, since the average particle diameter of the phosphor is small in diameter of 4.0 µm or less, the light emitting layer containing the phosphor can be densified (densified) to improve the smoothness of the fluorescent surface. Therefore, the breakdown voltage characteristic of the display device is greatly improved.

In order to form a fluorescent substance layer using the blue light emitting fluorescent substance of embodiment of this invention, it can carry out using a well-known slurry method or the printing method. In the slurry method, a powder of blue light-emitting phosphor is mixed with photosensitive material such as pure water, polyvinyl alcohol, ammonium dichromate, surfactant, and the like to prepare a phosphor slurry, and the slurry is coated and dried by a spin coater or the like, followed by ultraviolet rays or the like. The blue light emitting phosphor layer can be formed by drying the phosphor pattern obtained by exposing and developing a predetermined pattern.

Next, a field emission display device (FED) in which a blue phosphor layer is formed using the blue light emitting phosphor according to the embodiment of the present invention will be described.

It is sectional drawing which shows the structure of the principal part of one Embodiment of FED. In FIG. 2, the code | symbol 11 is a face plate, and has the phosphor layer 13 formed on transparent substrates, such as the glass substrate 12. As shown in FIG. The phosphor layer 13 has a blue light emitting phosphor layer, a green light emitting phosphor layer, and a red light emitting phosphor layer formed in correspondence with pixels, and is separated from each other by a light absorbing layer 14 containing a black conductive material. It is. Of the phosphor layers of each color constituting the phosphor layer 13, the blue light emitting phosphor layer is composed of the blue light emitting phosphor of the above embodiment.

The thickness of the blue light emitting phosphor layer is preferably 1 to 12 m, more preferably 3 to 9 m. The thickness of the blue light emitting phosphor layer is limited to 1 μm or more because it is difficult to form a phosphor layer in which the phosphor particles are uniformly arranged while the thickness is less than 1 μm. In addition, when the thickness of the blue light emitting phosphor layer exceeds 12 µm, the light emission luminance is lowered, which is not practical.

The green light emitting phosphor layer and the red light emitting phosphor layer can be composed of various known phosphors, respectively. It is preferable that the thickness of the green light emitting phosphor layer and the red light emitting phosphor layer is also the same as that of the blue light emitting phosphor layer so that a step does not occur between the phosphor layers of each color.

The above-mentioned blue light emitting phosphor layer, green light emitting phosphor layer, red light emitting phosphor layer and the light absorbing layer 14 separating them are each sequentially formed in the horizontal direction, and these phosphor layers 13 and the light absorbing layer 14 are respectively formed. The part in which is present becomes an image display area. Various patterns, such as a dot form or a stripe form, can be applied to the arrangement pattern of the phosphor layer 13 and the light absorbing layer 14.

The metal back layer 15 is formed on the phosphor layer 13. The metal back layer 15 consists of metal films, such as Al film, and reflects the light which progresses in the rear plate direction mentioned later among the light which generate | occur | produced in the phosphor layer 13, and improves a brightness | luminance. In addition, the metal back layer 15 has a function of providing conductivity to the image display area of the face plate 11 to prevent charge from accumulating, and serves as an anode electrode for the electron source of the rear plate. In addition, the metal back layer 15 has a function of preventing the phosphor layer 13 from being damaged by ions generated by ionization of the gas remaining in the face plate 11 or the vacuum container (environment) with an electron beam.

On the metal back layer 15, a getter film 16 formed of an evaporative getter material containing Ba or the like is formed. By this getter film 16, the gas generated at the time of use is adsorbed efficiently.

In addition, the face plate 11 and the rear plate 17 are disposed to face each other, and the space therebetween is hermetically sealed through the support frame 18. The support frame 18 is joined to the face plate 11 and the rear plate 17 by a bonding material 19 containing frit glass, In, an alloy thereof, or the like, and the face plate 11 and the rear plate ( 17) and the support frame 18 constitute a vacuum container as an envelope.

The rear plate 17 has a substrate 20 including an insulating substrate such as a glass substrate, a ceramic substrate, a Si substrate, or the like, and a large number of electron emission elements 21 formed on the substrate 20. These electron emission elements 21 are provided with, for example, a field emission type cold cathode, a surface conduction type electron emission element and the like, and wirings not shown are shown on the formation surface of the electron emission element 21 of the rear plate 17. Is installed. That is, many electron emission elements 21 are formed in matrix form according to the fluorescent substance of each pixel, and have the wiring (XY wiring) which mutually crosses each other, and drives this matrix electron emission element 21 one by one. . In addition, the support frame 18 is provided with the signal input terminal (not shown) and the terminal for row selection. These terminals correspond to the cross wiring (X-Y wiring) of the rear plate 7. In addition, when increasing the size of a flat plate type FED, since it is a thin plate shape, there exists a possibility that bending etc. may arise. The reinforcing member (spacer) 22 may be appropriately disposed between the face plate 11 and the rear plate 27 to prevent such bending and to impart strength to atmospheric pressure.

In the FED, since the blue light emitting phosphor of the above embodiment is used as the blue light emitting phosphor layer that emits light by electron beam irradiation, display characteristics such as initial luminance (white luminance) and color reproducibility are improved, and have high breakdown voltage characteristics. .

Next, specific examples of the present invention will be described.

<Example 1>

To the ZnS raw material, which is the phosphor matrix, a predetermined amount of activator raw material (such as silver nitrate for Ag and aluminum nitrate for Al) is added, and fluxes such as potassium chloride and magnesium chloride are added as necessary, and they are wetted. Mixed. The resulting slurry was transferred to a drying container, dried in a dryer, and used as a phosphor raw material.

Subsequently, the above-mentioned phosphor raw material was put into the heat resistant container of the baking apparatus shown in FIG. 1 with an appropriate amount of sulfur and activated carbon. The heat resistant container was made of quartz or alumina, and had an inner diameter of 60 mm and a length of 1000 mm. In addition, the rotation speed was 0.5 to 10 rotations / minute, and the inclination angle was 1 to 5 degrees. Further, the injected phosphor raw material is continuously passed through an inside of a heating unit maintained in an inert gas or a reducing gas atmosphere (at an atmosphere of 3 to 5% hydrogen-remaining nitrogen) in an oxygen-free state for 15 to 45 minutes, and heated to 980 to 1230 ° C. After firing, the fired product was rapidly cooled in the cooling unit.

Subsequently, the obtained calcined product was washed with ion-exchanged water or the like and dried, and then sifted to remove coarse particles if necessary, thereby obtaining a hexagonal zinc sulfide phosphor (ZnS: Ag, Al). In addition, the average particle diameter d of the hexagonal zinc sulfide phosphor obtained was measured by the transmission method, and the molar ratio (S / Zn) of the sulfur atom and the zinc atom was measured by XPS.

Subsequently, the phosphor layer was formed by the slurry method using the obtained phosphor. The phosphor layer was formed by dispersing the phosphor in an aqueous solution containing polyvinyl alcohol or the like to form a slurry, and applying the slurry onto a glass substrate with a spin coater (spin coater). By adjusting the rotation speed of the rotary applicator and the viscosity of the slurry, the thickness of the phosphor layer was 3 × 10 ⁻³ mg / mm ³ .

The luminescence brightness and chromaticity of the phosphor layer thus formed were examined, respectively. The emission luminance was measured by irradiating an electron beam with an acceleration voltage of 10 kV and a current density of 2 × 10 ^-5 A / mm ^{2 to} the phosphor layer. In addition, it was calculated | required as the relative value at the time of making into 100% the light emission luminance of the comparative example 1 which mentions the light emission luminance of the fluorescent substance layer at this time.

In addition, the emission chromaticity was measured using SR-3 by Topcon Corporation as a chromaticity measuring instrument. The emission chromaticity was measured in a dark room in which the chromaticity at the time of emission was not influenced from the outside. The measurement results of the emission luminance and emission chromaticity are shown in Table 1 together with the average particle diameters d and S / Zn.

Comparative Example 1

The same phosphor raw material as in Example 1 was charged into a quartz crucible together with an appropriate amount of sulfur and activated carbon, and 30 to a temperature of 1050 to 1230 ° C. in a hydrogen sulfide atmosphere or a reducing atmosphere (at an atmosphere of 3 to 5% hydrogen-remaining nitrogen). It baked by heating for 360 minutes. After firing, the crucible was left at room temperature and naturally cooled in a nitrogen atmosphere.

Subsequently, the obtained calcined product was washed with ion-exchanged water or the like and dried, and then, if necessary, sieve fractionation to remove coarse particles was carried out to obtain a hexagonal zinc sulfide phosphor. The average particle diameters d and S / Zn of the hexagonal zinc sulfide phosphors thus obtained were measured in the same manner as in Example 1.

Subsequently, the phosphor layer was formed by the slurry method using the obtained phosphor, and the light emission luminance and light emission chromaticity of this phosphor layer were irradiated in the same manner as in Example 1. In addition, the light emission luminance of the phosphor layer at this time was 100%. The measurement results of the luminance and the chromaticity of the emission are shown in Table 1 together with the values of the average particle diameters d and S / Zn.

<Examples 2 to 6>

The same phosphor raw material as in Example 1 was introduced into a heat resistant container of a calcination apparatus together with an appropriate amount of sulfur and activated carbon, heated and fired in the same manner as in Example 1 while rotating the heat resistant container, and then the fired product was rapidly cooled in the cooling section. Cooled. At this time, the average particle diameter d was adjusted by changing heating conditions (heating temperature, passage time) and the like, and a hexagonal zinc sulfide phosphor having an average particle diameter d shown in Table 1 was prepared. In addition, the average particle diameters d and S / Zn of the hexagonal zinc sulfide phosphors thus obtained were measured in the same manner as in Example 1.

Subsequently, using these phosphors, the phosphor layer was formed on the glass substrate by the slurry method, and the luminescence brightness and chromaticity of the phosphor layer were irradiated in the same manner as in Example 1. These measurement results are shown in Table 1 together with the values of the average particle diameter d and S / Zn.

As is clear from Table 1, the hexagonal zinc sulfide phosphors obtained in Examples 1 to 6 had a high luminescence luminance when a high current density electron beam was irradiated at a low speed voltage (15 kV or less), and had good luminescence chromaticity. In contrast, the hexagonal zinc sulfide phosphor of Comparative Example 1 was inferior to Examples 1 to 6 in terms of emission luminance.

<Example 7>

The hexagonal zinc sulfide phosphor obtained in Example 1 was used as a blue light emitting phosphor, and green light emitting phosphors (ZnS: Cu, Ag phosphors) and red light emitting phosphors (Y ₂ O ₂ S: Eu phosphors) were used on a glass substrate. Phosphor layer was formed in and it was set as face plate. The face plate and the rear plate having a plurality of electron emission elements were assembled through a support frame, and at the same time, these gaps were hermetically sealed while evacuating them. Thus, it was confirmed that the FED obtained was excellent in color reproducibility and exhibited good display characteristics even after driving for 1000 hours at normal temperature and rated operation.

According to the blue light-emitting phosphor of the present invention, when the electron beam having a high current density is irradiated at low voltage, the color purity is good with high luminance, and blue light emission with a long lifetime can be realized. In addition, the breakdown voltage characteristics of a thin flat display such as FED can be significantly improved. Moreover, according to the manufacturing method of this invention, hexagonal zinc sulfide fluorescent substance of the small particle diameter can be manufactured, without a brightness fall, and the blue light emitting fluorescent substance of this invention can be obtained efficiently.

Claims (7)

A phosphor containing a zinc sulfide phosphor having a hexagonal crystal structure of silver and aluminum as an activator (hereinafter referred to as "hexagonal system"), which is excited by an electron beam having an acceleration voltage of 15 kV or less, and emits blue light. , The hexagonal silver and aluminum-activated zinc sulfide phosphors have a mean particle size of 1.0 to 4.0 µm. The method of claim 1, wherein the hexagonal silver and aluminum-activated zinc sulfide phosphor has a molar ratio (S / Zn) of sulfur atoms and zinc atoms measured by X-ray photoelectron spectroscopy (XPS) to be more than 0.97 and not more than 1.0. A blue light emitting phosphor for display device. And a step of heating and firing a phosphor raw material comprising an element constituting the phosphor matrix and an activator or a compound containing the element, In the firing step, continuously passing through a rotating tubular heating furnace in which the phosphor raw material is inclined with respect to the horizontal, is heated in the heating furnace and calcined, and at the same time firing material continuously discharged from the heating furnace It cools, The manufacturing method of the blue light emitting fluorescent substance for display apparatus of Claim 1 or 2 characterized by the above-mentioned. The method of manufacturing a blue light-emitting phosphor for a display device according to claim 3, wherein the inside of the heating furnace is maintained in an oxygen-free state. The method of manufacturing a blue light-emitting phosphor for a display device according to claim 3 or 4, wherein the inside of the heating furnace is maintained in an inert gas atmosphere or a reducing gas atmosphere. The inclination angle of the said heating furnace is adjusted so that the said fluorescent material raw material may remain in the said heating furnace for the time enough for baking, moving the inside of the said heating furnace, The said phosphor raw material is characterized by the above-mentioned. The manufacturing method of the blue light emitting fluorescent substance for display apparatuses. A phosphor layer comprising a blue light emitting phosphor layer, a green light emitting phosphor layer, and a red light emitting phosphor layer, an electron emission source for emitting light by irradiating an electron beam having an acceleration voltage of 15 kV or less on the phosphor layer, the electron emission source, and the phosphor layer And a field emission display device having an enclosure for vacuum sealing them together. The blue light emitting phosphor layer comprises the blue light emitting phosphor for display device according to claim 1 or 2.

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