JP2001166717A - Fluorescent sheet and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fluorescent sheet for solving problems such as color- mixing in the case of a color image without deteriorating the resolution of the fluorescent sheet even when a phosphor layer is thickened in order to increase the fluorescent efficiency. SOLUTION: This fluorescent sheet contains phosphors and has a photonic crystal section consisting of a nano hole layer of alumina for forming a bandgap with respect to a fluorescent wavelength in the intra-sheet surface direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a fluorescent sheet and a method for producing the same. In particular, the fluorescent sheet provided with the photonic crystal of the present invention is effective as an electron-beam-excited, X-ray-excited, or ultraviolet-excited fluorescent sheet. In particular, it can be applied as a fluorescent sheet, a fluorescent film, a fluorescent screen, etc. having both high conversion efficiency and high resolution.

[0002]

2. Description of the Related Art Conventional phosphors have been used in which a powder of a fluorescent material is applied or a sheet in which a fluorescent material is dispersed in a medium. As a fluorescent material, for example, as a red phosphor for CRT, starting from Zn ₃ (PO ₄ ) ₂ : Mn ²⁺ , passing through (Zn, Cd) S: Ag, YVO ₄ : Eu ³⁺ ,
Y ₂ O ₃ : Eu ³⁺ and Y ₂ O ₂ S: Eu ³⁺ have been developed.
Green has a Tb activated phosphor such as Y _{3 A 15} O ₁₂ : Tb ³⁺ , and blue has ZnS: Ag or (La, Y) OB.
r: Ce ³⁺ , (La, Gd) OBr: Ce ^{3+ and the} like are used.

As a white phosphor for CRT, InB
O ₃ : Tb ³⁺ , InBO ₃ : Eu ³⁺ , Y ₂ O ₂ S: Tb ³⁺
Such powders have been used.

As a fluorescent material for a fluorescent lamp, a material Sr ₂ activated with Eu ³⁺ is used as blue (blue-green, blue-violet).
_{P 2 O 7, (Sr,} Ca) 10 (PO 4) 6 C1 2, BaM
g ₂ A1 ₁₆ O ₂₇ , 2SrO · 0.84 P ₂ O ₅ · 0.1
6B ₂ O ₃ , (Ba, Ca, Mg) ₁₀ (PO ₄ ) ₆ Cl
₂ , Sr ₄ Al ₁₄ O _{25 and the} like. As the red phosphor, Eu ³⁺ activated materials Y ₂ O ₂ , Y (P,
V) O _{4 and the} like are green phosphors such as Ce ³⁺ and Tb ³⁺
Activated materials LaPO ₄ , MgA1 ₁₁ O ₁₉ , GdMg
B ₅ O _{10 and the} like.

As X-ray phosphors, materials such as CaWO ₄ and Td ³⁺ activated Gd ₂ O ₂ S, La ₂ O ₂ S,
Material L activated with LaOBr, Y ₂ O ₂ S powder or Tm ³⁺
aOBr, YTaO ₄ powder or BaF activated with Eu ⁺²
BaF activated with Eu ⁺² as an X-ray intensifying screen
Gd ₂ O ₂ S activated with Pr ³⁺ or the like has been used as an imaging plate such as Br, and as an X-ray scintillator.

Further, CsI: Tl which is an X-ray simultaneous phosphor
Stimulable phosphor layers such as SrS: Ce ³⁺ , BaClBr and BaFB, and (Zn, Cd) S, Gd ₂ O ₂ S, etc.
r: Eu and the like may be used in combination. (Japanese Unexamined Patent Publication (Kokai) No. 05-264799) A fluorescent display panel using low-voltage electron beam excitation of 10 to 100 V is made of Zn.
O: Zn, SnO ₂ : Eu ³⁺ , Y ₂ O ₃ : Eu ³⁺ + In
₂ O _{3 and the} like have been used.

A photonic crystal is an artificial multidimensional periodic structure imitating a molecular crystal, and is composed of a structure in which two or more materials having different refractive indexes are periodically arranged. Such a medium forms a photonic band depending on conditions, which can be inferred from the theory of band formation of a semiconductor. That is, the dispersion relationship between the energy E and the wave number k forms a band due to the Bragg reflection of the electron wave, and the periodicity of the wavelength also produces a photonic band in the light. Here, a wavelength region where light cannot exist is called a photonic band gap, and changes according to a periodic structure or a change in refractive index. This periodicity has a size of about the wavelength of light to a fraction of the wavelength of light, and in recent years, photonic crystals having a two-dimensional or three-dimensional structure have been mainly studied. The production of these photonic crystals has begun to be studied mainly by semiconductor processing techniques centering on photolithography.

[0008] In addition to such a manufacturing method similar to that of a semiconductor element, a new photonic crystal is to be realized by utilizing a regular structure formed naturally, that is, a structure formed by self-organization. There is an attempt to do. These methods include a method of arranging microspheres and a method of bundling fibers, and an anodized alumina film (for example, RC Furneaux, W.C.).
R. Rigby & A. P. Davidson "NATU
RE "Vol. 337, P147 (1989), etc.] Anodizing an Al plate in a certain kind of acidic electrolyte forms a porous oxide film.
Is anodized to form a porous alumina nanohole layer 5 on the surface.
FIG. 2 is a schematic cross-sectional view of a nanohole layer formed from No. 2. As shown in FIG. 7, the feature of the anodized alumina film is that, for example, extremely fine columnar pores (alumina nanoholes) 53 having a diameter 2r of several nm to several hundred nm are parallel at an interval 2R of several tens to several hundred nm. In that it has a specific geometric structure arranged in The columnar alumina nanoholes 53 have a high aspect ratio and are excellent in the uniformity of the cross-sectional diameter. In addition, the diameter 2r and the interval 2R of the alumina nanoholes 53 can be controlled to some extent by adjusting the current and voltage during anodic oxidation. Further, a barrier layer (a layer of Al oxide) 54 exists between the anodized alumina nanoholes 53 and the aluminum foil. Attention has been paid to the specific geometric structure of the alumina nanohole film formed by this anodic oxidation, and various applications have been attempted so far.

In the meantime, the production of a photonic crystal by the semiconductor processing technique described above has problems such as a low yield and a high cost of an apparatus. Therefore, a method that can be produced with a simple method and high reproducibility is desired. From such a viewpoint, the above-described self-organizing method, particularly, the method of anodic oxidation of Al has an advantage that a photonic crystal can be easily and well controlled. In addition, these self-assembly techniques can generally produce large-area nanostructures.

[0010]

The efficiency of the phosphor also depends on the composition and shape of the phosphor powder and the thickness of the phosphor applied. As a general tendency, when the thickness of the phosphor layer is increased to increase the luminous efficiency, the efficiency is increased but the resolution is reduced, and in the case of a color image, there are problems such as mixing of colors.

An object of the present invention is to solve these problems. Even if the phosphor layer is made thicker to increase the fluorescence efficiency, the resolution of the phosphor sheet does not decrease, and in the case of a color image, An object of the present invention is to provide a phosphor sheet provided with a photonic crystal that can solve problems such as color mixing. Another object of the present invention is to provide a method for manufacturing a fluorescent sheet provided with the photonic crystal.

[0012]

That is, a first aspect of the present invention is to provide a phosphor sheet provided with a phosphor, wherein a photonic crystal portion having a band gap in a sheet in-plane direction with respect to a fluorescence wavelength. It is a fluorescent sheet characterized by having.

It is preferable that the fluorescent sheet is composed of a fluorescent layer composed of a phosphor and a photonic crystal layer composed of a photonic crystal part, and that the fluorescent layer and the photonic crystal layer have a laminated structure. Preferably, the photonic crystal part has an alumina nanohole layer.

It is preferable that the photonic crystal portion is formed by filling a phosphor in alumina nanoholes. Preferably, the alumina nanohole layer has fluorescent properties. It is preferable that the nanoholes of the alumina nanohole layer are regularly arranged in a honeycomb shape.

Preferably, the phosphor is an X-ray phosphor, an electron beam phosphor or an ultraviolet phosphor. It is preferable to have a fluorescent reflection layer on at least one side of the sheet surface. Preferably, the fluorescent reflection layer is made of aluminum.

Further, a second invention of the present invention is a method for producing a fluorescent sheet, comprising the steps of: forming an alumina nanohole by anodizing an aluminum substrate; and filling a phosphor in the alumina nanohole. Is the way.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The phosphor sheet of the present invention is characterized in that, in the phosphor sheet provided with a phosphor, a photonic crystal portion having a band gap in the in-plane direction with respect to the fluorescence wavelength is provided. I do.

In this fluorescent sheet, the fluorescent sheet has a fluorescent layer and the fluorescent layer is formed of a fluorescent sheet having photonic crystal characteristics, or the fluorescent sheet has a fluorescent layer and a photonic crystal layer, Further, a fluorescent sheet in which the fluorescent sheet has a stacked structure of a fluorescent layer and a fluorescent layer is preferable.

In the above fluorescent sheet, a fluorescent sheet characterized in that the photonic crystal is composed of an alumina nanohole layer is effective, but the fluorescent sheet in which a phosphor is embedded in the nanohole or the alumina nanohole layer is formed. A fluorescent sheet having fluorescent characteristics is preferred.

Next, the fluorescent sheet of the present invention will be described with reference to the drawings. FIG. 1 is a conceptual diagram showing an example of the fluorescent sheet of the present invention. FIG. 1 (a) is a plan view, and FIG.
FIG. 2 shows a cross-sectional view taken along line AA ′ of the fluorescent sheet shown in FIG.
In FIG. 1, reference numeral 11 denotes a nanohole layer, and 12 denotes a nanohole in which a phosphor is embedded.

FIG. 1 shows a two-dimensional photonic crystal.
As an example, here, the photonic crystal layer and the fluorescent layer are formed of the same layer (nanohole layer). Further, the diameter and the interval of the nanoholes are about a fraction of the fluorescence wavelength to the fluorescence wavelength, and when the fluorescence is visible light, several tens of nanoholes are obtained.
It is about 0 nm.

In FIG. 1, the photonic crystal has a photonic band having a band gap in the in-plane direction of the sheet with respect to the fluorescence wavelength. The fluorescent light propagates in the in-plane direction of the sheet. It is hard to be done. However, fluorescence can easily be emitted in the sheet vertical direction 3.

FIG. 2 is a conceptual diagram showing excitation and emission of the fluorescent sheet of the present invention. In FIG. 2, a reflection layer 22 is provided on one side of the fluorescent sheet of FIG. 1. For example, when electrons are accelerated and driven as an excitation source from the upper part of FIG.
The electrons impinge on the photonic crystal fluorescent layer 21 to emit fluorescence. At this time, the light traveling toward the upper part of the fluorescent light is reflected by the reflective layer 22, and the fluorescent light emitted in the lateral direction is suppressed by the influence of the photonic band. As a result, the emitted fluorescence will be strongly directed in the opposite direction to the excitation source.

FIG. 3 is a conceptual diagram showing the laminated fluorescent sheet of the present invention. FIG. 3A shows an example of a phosphor sheet having a structure in which the photonic crystal phosphor layer of the phosphor sheet of FIG. 2 is separated into a phosphor layer 32 and a photonic crystal layer 31, and FIG. 5 is an example of a fluorescent sheet having a structure in which a plurality of photonic crystal layers are stacked.

<Regarding Anodized Alumina> Although a two-dimensional photonic crystal is most suitable for the present invention, it is effective to use an anodizing method of aluminum for producing this structure.

In the fluorescent sheet, the thickness of the fluorescent layer is desirably 10 μm or more in consideration of the fluorescent light as visible light in order to increase the efficiency. As described above, the nanohole itself has a size of about several hundred nm, and therefore, the aspect ratio of the nanohole needs to be several tens or more. In order to realize such an anisotropic structure in a certain area, a chemical method such as anodic oxidation is effective. The anodized alumina nanoholes will be briefly described below.

Anodized alumina nanoholes are produced by anodizing an Al film, aluminum foil, aluminum plate or the like in a specific acidic solution. When an Al film is used, a sputtering method and a vacuum deposition method are generally used for forming the Al film.

The structure of the anodic alumina nanoholes is the same as the sectional view shown in FIG. The alumina nanohole layer 52 contains Al and oxygen as main components and has a large number of columnar nanoholes 53. The nanoholes 53 are arranged almost perpendicularly to the surface of the base, and the respective nanoholes are parallel and substantially parallel to each other. They are arranged at equal intervals. The diameter 2r of the obtained alumina nanohole is several nm to several hundred nm, and the interval 2R is about several tens nm to several hundred nm, and can be controlled by the anodic oxidation conditions. Further, the thickness of the alumina nanohole layer 52 and the depth of the nanoholes can be controlled by the anodic oxidation time and the like. This is, for example,
It is between 00 μm.

The diameter of the alumina nanoholes can be increased by etching. For this, a phosphoric acid solution or the like can be used.

In order to form anodized alumina nanoholes regularly, in addition to a two-stage anodic oxidation method as described later, a method of forming honeycomb-shaped irregularities on the Al surface by a stamp method or the like and then performing anodization. There is. (For details, see Masuda: "OPTRONICS" No. 8 (1998) 21)
1) <Method of Manufacturing Fluorescent Sheet> Hereinafter, a method of manufacturing the fluorescent sheet of the present invention will be described with reference to FIGS. 5 and 6 are conceptual views showing steps of the method for producing a fluorescent sheet of the present invention, and FIG. 4 is a schematic view showing an anodizing apparatus. FIG. 5 is a conceptual diagram showing an Al back fluorescent sheet of the present invention, and FIG. 6 is a conceptual diagram showing a metal electrode back fluorescent sheet.

The following steps (a) to (c) correspond to FIG.
(C) and FIGS. 6 (a) to (c).

(A) Anodizing pretreatment step of aluminum foil As shown in FIG. 5A, an aluminum foil 5 having a thickness of about 50 μm
1 or an aluminum foil 51 provided with a metal electrode 61 such as Nb on the back as shown in FIG. At this time, it is effective to form irregularities on the surface of the aluminum foil so as to be a starting point of nanoholes for anodic oxidation. The irregularities are preferably formed in a honeycomb shape in order to produce nanoholes having a large aspect ratio. Various processes, such as a stamp method and a semiconductor lithography method, can be used for processing the unevenness. Various methods such as a sputtering method, a CVD method, and a vacuum evaporation method can be used for manufacturing the metal electrode 61.

(B) Anodizing step Next, the aluminum foil is subjected to anodizing method to produce linano holes. In FIG. 4, 40 is a thermostat, 41 is a sample, 42 is a cathode (platinum electrode) of a Pt plate, 43 is an electrolyte, 44 is a reaction vessel, 45 is a power supply for applying an anodic oxidation voltage, 46 is an anode. Ammeter for measuring oxidation current, 47
Is a sample holder. Although not shown in the figure, a computer for automatically controlling and measuring the voltage and current is incorporated.

The sample 41 and the cathode 42 are disposed in an electrolyte maintained at a constant temperature by a constant temperature water bath, and anodization is performed by applying a voltage between the sample and the cathode from a power supply.

The electrolyte used for the anodic oxidation includes, for example, oxalic acid, phosphoric acid, sulfuric acid, chromic acid solution and the like. A particularly preferred solution is sulfuric acid at a low voltage (about 30 V), phosphoric acid at a high voltage (80 V or more), and an oxalic acid aqueous solution at a voltage in between.

When an electrode is taken from the back surface of the aluminum foil or from the metal electrode 61 and subjected to constant voltage anodic oxidation in an acid solution, the surface of the aluminum foil is first oxidized and the current value drops rapidly, but nanoholes begin to be formed. And the current gradually increases and becomes constant. When the anodic oxidation reaches the back surface or below the metal electrode, oxidation of Al and diffusion of Al ions into the aqueous solution are suppressed, and the current value changes. At this time, when the anodic oxidation is completed while leaving a little Al, the barrier layer 54 remains on the bottom of the nanohole as shown in FIG. The Al remaining portion can also be used as a fluorescent reflection layer. When Al is unnecessary, it is also possible to immerse in saturated mercuric chloride to dissolve only the Al layer. It is also possible to use a method in which a voltage is applied in reverse to peel off the oxide layer (reverse electrolysis peeling method). When the metal electrode 61 is used, a penetrating nanohole or a nanohole having a conductive path can be formed depending on the type of the metal.

As a method of ordering the alumina nanoholes, a two-stage anodic oxidation method can be used in addition to the above-described method of forming irregularities on the Al surface. The two-stage anodic oxidation method will be described below.

First, when anodic oxidation is performed for a long time under special conditions (eg, oxalic acid 0.3M40V) as the first stage of anodic oxidation, nanoholes are arranged in a honeycomb shape by self-ordering. At this point, if the anodic oxide layer is dissolved in a mixed solution of chromic acid and phosphoric acid, honeycomb-shaped irregularities corresponding to the concave portions where the lower portions of the nanoholes remain on the Al surface. Next, when anodic oxidation is performed again, the concave portion on the Al surface acts as a starting point, and alumina nanoholes are formed in a honeycomb shape as the anodic oxidation proceeds.

Although the above-mentioned two-stage anodic oxidation method has problems such as a hole interval between honeycomb nanoholes and existence of defects, it is an effective means since ordered nanoholes can be easily obtained in a large area.

By immersing the alumina nanohole layer in an acid solution (for example, a phosphoric acid solution), the nanohole diameter can be appropriately increased. Alumina nanoholes having a desired nanohole diameter can be obtained by controlling the acid concentration, processing time, and temperature.

(C) Inclusion Inclusion Step There is a method such as electrodeposition for embedding inclusions in the nanoholes. In the case of electrodeposition, the aluminum foil on which the nanoholes are formed is immersed in a solution in which the electrodeposited metal is a cation, and a voltage may be applied from the base side. For example, 60 ° C
By immersing in a 0.1 M aqueous solution of zinc nitrate together with a platinum counter electrode and applying a negative voltage, ZnO crystals can be grown in the nanoholes.

It is also effective to apply an AC voltage or a pulse voltage to sufficiently generate nuclei during electrodeposition. Conversely, when anions are to be electrodeposited or oxidized simultaneously, a positive voltage must be applied.

In this case, the electrodeposition sometimes includes precipitation of a hydroxide or the like by field oxidation. That is,

[0044]

Embedded image Reaction occurs on the anode surface. Here, another ion is taken in the precipitate at the same time as another ion. Ie

[0045]

Embedded image May occur.

After the nanoholes are filled with inclusions by electrodeposition or the like, it is also effective in some cases to polish the surface to flatten the nanohole surface. In order to embed the phosphor in the nanoholes, the above-described electrodeposition method is simple and has good controllability. However, other than the electrodeposition method, other methods such as an electrophoresis method, a coating method, a penetration method, and a CVD method may be used. The membrane method can be used.

In the present invention, the fluorescent sheet having the photonic band is limited. However, even if the photonic band gap is not completely opened, the effect of the present invention appears if the state density at the fluorescent wavelength is sufficiently reduced. . That is, in the present invention, the photonic band gap includes the case where the state density is sufficiently reduced.

[0048]

The present invention will be described below with reference to examples.

Example 1 In this example, an electron beam and ultraviolet phosphor using alumina nanoholes will be described with reference to FIG.

First, an aluminum foil 51 having a thickness of 50 μm was prepared, and the surface of the aluminum foil 51 was formed into a honeycomb shape using a stamp so that the interval between the concave portions was about 260 nm. At this time, the height of the unevenness was about 300 nm. Next, the aluminum foil surface is anodized by the anodizing apparatus shown in FIG. In FIG. 4, reference numeral 40 denotes a thermostat, 41 denotes a sample, 42 denotes a cathode of a Pt plate, 43 denotes an electrolyte, 44 denotes a reaction vessel, 45 denotes a power supply for applying an anodizing voltage, and 46 measures an anodizing current. Ammeter,
47 is a sample holder. Although not shown in the figure, a computer for automatically controlling and measuring the voltage and current is incorporated.

The sample 41 and the cathode 42 are arranged in an electrolyte maintained at a constant temperature by a constant temperature water bath, and anodization is performed by applying a voltage between the sample and the cathode from a power supply.

The anodic oxidation was performed by applying 0.3 V of phosphoric acid at 110 ° C. with an electrolyte at 3 ° C. Then, the anodic oxidation was completed while leaving a little Al. The diameter of the nanoholes was increased to about 150 nm by immersing the alumina nanohole layer in 5 wt% of a phosphoric acid solution for 60 minutes.

As a result, as shown in FIG. 5B, the barrier layer 54 remains at the bottom of the nanohole, and the Al remaining portion becomes a fluorescent reflection layer. Next, the prepared aluminum foil was immersed together with a platinum counter electrode in an aqueous solution of zinc nitrate 0.1 M maintained at 60 ° C., and a negative voltage of about 5 V was applied to grow ZnO crystals in the nanoholes. Was.

After the sample taken out was sufficiently dried, it was placed in a vacuum apparatus equipped with an electron gun, evacuated to 10 ^-6 Pa, and then electrons accelerated to 500 V from the Al surface side had a diameter of about 0.1 mm. When the sample was irradiated with a size of, fluorescence was observed. For comparison, the ZnO: Zn phosphor was also changed to I
When the same fluorescence was observed using a fluorescent plate coated on the surface of the glass with TO with a thickness of 50 μm, the fluorescent intensity was almost the same, but the fluorescent region of the present invention was smaller by about 30%.

When the same experiment was performed by irradiating ultraviolet rays other than the electron beam irradiation, similar results were obtained. When the transmittance of the fluorescent sheet of the present invention was measured while changing the incident angle of light, it was suggested that a photonic band gap was present in the in-plane direction of the sheet. This indicates that the present invention functions as an electron beam fluorescent sheet or an ultraviolet fluorescent sheet having excellent resolution.

Embodiment 2 In this embodiment, a phosphor for electron beams and ultraviolet rays using alumina nanoholes will be described with reference to FIG.

First, an aluminum foil 51 having a thickness of 50 μm was prepared, W was sputter-deposited on the back surface to a thickness of 10 nm, and the surface was processed into a honeycomb shape with a stamp so that the interval between concave portions was approximately 260 nm. . At this time, the height of the unevenness is about 30
It was set to 0 nm. Next, the aluminum foil surface was anodized by the anodizing apparatus shown in FIG.

The anodic oxidation was performed by applying 0.3 V of phosphoric acid at 110 ° C. with an electrolyte at 3 ° C. Then, the anodic oxidation was completed so as not to leave the Al portion. The diameter of the nanoholes was increased to about 200 nm by immersing the alumina nanohole layer in 5 wt% of a phosphoric acid solution for 80 minutes.

As a result, as shown in FIG. 6B, nanoholes are present up to the bottom of the nanoholes, and the W film becomes a fluorescent reflection layer. Next, the prepared aluminum foil was immersed together with a platinum counter electrode in an aqueous solution of zinc nitrate 0.1 M maintained at 60 ° C., and a negative voltage of about 5 V was applied to grow ZnO crystals in the nanoholes. Was.

After the sample taken out was sufficiently dried, it was placed in a vacuum apparatus equipped with an electron gun, evacuated to 10 ^-6 Pa, and then electrons accelerated to 500 V from the Al surface side with a diameter of about 0.1 mm. When the sample was irradiated with a size of, fluorescence was observed. For comparison, the ZnO: Zn phosphor was also changed to I
When the same fluorescence was observed using a fluorescent plate coated on the surface of the glass with TO with a thickness of 50 μm, the fluorescent intensity was almost the same, but the fluorescent region of the present invention was smaller by about 30%.

When the same experiment was performed by ultraviolet irradiation other than electron beam irradiation, similar results were obtained. When the transmittance of the fluorescent sheet of the present invention was measured while changing the incident angle of light, it was suggested that a photonic band gap was present in the in-plane direction of the sheet. This indicates that the present invention functions as an electron beam fluorescent sheet or an ultraviolet fluorescent sheet having excellent resolution.

Example 3 A honeycomb-shaped alumina nanohole sheet was prepared in the same manner as in Example 1. However, the thickness of the aluminum foil 51 is about 20 μm, the nanohole diameter is expanded to about 200 nm, and extra aluminum is used.
The portion was dissolved by immersion in saturated mercury chloride.

Next, Gd ₂ O ₂ S was added to this sheet for about 20 minutes.
μm was applied. Three such laminated sheets were produced and laminated to produce a fluorescent sheet as shown in FIG. 3 (b).

The prepared sample was collimated to 100 μm
When the sample was irradiated with X-rays, fluorescence was observed. For comparison, similar fluorescence was observed using a phosphor plate coated with a phosphor of Gd ₂ O ₂ S at 60 μm on the surface of glass. The fluorescence intensity was almost the same, but the fluorescence region was smaller than that of the present invention. Was about 30% smaller.

When the transmittance of the fluorescent sheet of the present invention was measured while changing the incident angle of light, it was suggested that a photonic band gap existed in the in-plane direction of the sheet. This indicates that the present invention functions as an X-ray fluorescent sheet having excellent resolution.

Example 4 In this example, a phosphor sheet using fluorescent alumina nanoholes will be described with reference to FIG.

An aluminum foil 51 having a thickness of 50 μm was prepared in the same manner as in Example 1, and the surface of the aluminum foil 51 was formed into a honeycomb shape using a stamp so that the interval between the concave portions was about 230 nm. At this time, the height of the unevenness was about 300 nm. Next, the aluminum foil is anodized by the anodizing apparatus shown in FIG.

Also, an aluminum foil 51 having a thickness of 100 μm was prepared, subjected to anodization 50 μm without surface treatment, and then immersed in a mixed solution of phosphoric acid and chromic acid to remove an oxide layer.
Anodization was performed again under the same conditions. Here, a mixed solution of phosphoric acid and oxalic acid is used for anodic oxidation, and an electrolyte at 3 ° C.
V was applied. Then, the anodic oxidation was completed while leaving a little Al. The two types of alumina nanohole layers were treated in phosphoric acid to obtain a structure shown in FIG.

Next, as in the first embodiment, ultraviolet rays having a diameter of about 0.
When irradiation was performed at a size of 1 mm, fluorescence was observed although the intensity was lower than in Example 1. For comparison, ZnO: Z
n phosphor on the surface of glass with ITO
When the same fluorescence was observed and compared using the coated fluorescent plate, the fluorescent region of the present invention was smaller by about 40%. The fluorescent area of the two-stage anodized fluorescent sheet was about 20% smaller.

When the transmittance of the fluorescent sheet of the present invention was measured while changing the incident angle of light, it was suggested that a photonic band gap exists in the in-plane direction of the sheet. From this, it was found that the anodized alumina nanoholes themselves have the fluorescence property and the structure with more regularization has higher resolution.

[0071]

As described above, according to the phosphor sheet of the present invention, even if the phosphor layer is thickened to increase the fluorescence efficiency, the resolution of the phosphor sheet is not reduced, and the color image can be reproduced. In this case, the effect of solving problems such as color mixing was obtained. Further, according to the manufacturing method of the present invention, it is possible to easily manufacture a fluorescent sheet including the above-described photonic crystal.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing an example of a fluorescent sheet of the present invention.

FIG. 2 is a conceptual diagram showing excitation and emission of the fluorescent sheet of the present invention.

FIG. 3 is a conceptual diagram showing a laminated fluorescent sheet of the present invention.

FIG. 4 is a schematic view showing an anodizing apparatus.

FIG. 5 is a conceptual diagram showing an example of steps of a method for producing a fluorescent sheet of the present invention.

FIG. 6 is a conceptual diagram showing another example of the steps of the method for producing a fluorescent sheet of the present invention.

FIG. 7 is a schematic diagram showing anodized alumina nanoholes on an Al plate (film).

[Explanation of symbols]

 1, in-sheet direction 3 sheet vertical direction 11 nanohole layer 12 nanohole 21 photonic crystal fluorescent layer 22 reflective layer 31 photonic crystal layer 32 fluorescent layer 40 constant temperature bath 41 sample 42 cathode 43 electrolyte 44 reaction vessel 45 power supply 46 ammeter 47 Sample holder 51 Aluminum foil 52 Alumina nanohole layer 53 Alumina nanohole 54 Barrier layer 55 Phosphor 61 Metal electrode 62 Nanohole bottom

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4H001 CA01 XA08 XA30 5C096 AA01 AA27 BA04 BB27 BB39 CA03 CA15 CA26 CA28 CB01 CC02 CC23 CC36 CC38 CG17 EA01 EA03 EB02 EB12

Claims (12)

[Claims] 1. A fluorescent sheet provided with a phosphor,
A fluorescent sheet having a photonic crystal portion forming a band gap in a sheet in-plane direction with respect to a fluorescent wavelength. 2. The phosphor sheet according to claim 1, wherein the phosphor sheet comprises a phosphor layer composed of a phosphor and a photonic crystal layer composed of a photonic crystal part, and the phosphor layer and the photonic crystal layer have a laminated structure. . 3. The phosphor sheet according to claim 1, wherein the photonic crystal portion has an alumina nanohole layer. 4. The phosphor sheet according to claim 3, wherein the photonic crystal portion is formed by filling a phosphor into alumina nanoholes. 5. The fluorescent sheet according to claim 3, wherein the alumina nanohole layer has a fluorescent property. 6. The fluorescent sheet according to claim 3, wherein the nanoholes of the alumina nanohole layer are regularly arranged in a honeycomb shape. 7. The phosphor sheet according to claim 1, wherein said phosphor is an X-ray phosphor. 8. The phosphor according to claim 1, wherein said phosphor is an electron beam phosphor.
6. The fluorescent sheet according to any one of items 5 to 5. 9. The phosphor according to claim 1, wherein said phosphor is an ultraviolet phosphor.
6. The fluorescent sheet according to any one of items 5 to 5. 10. The fluorescent sheet according to claim 1, further comprising a fluorescent reflection layer on at least one side of the sheet surface. 11. The fluorescent sheet according to claim 10, wherein said fluorescent reflection layer is made of aluminum. 12. The method according to claim 3, further comprising a step of forming an alumina nanohole by anodizing an aluminum substrate and a step of filling a phosphor in the alumina nanohole. A method for manufacturing a fluorescent sheet.