JP2003202400A - Method for manufacturing radiation image conversion panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a radiation image conversion panel which produces radiation images of high picture quality. <P>SOLUTION: In the method for manufacturing the radiation image conversion panel which includes a process of forming a phosphor layer through the evaporation of a substance generated by heating an vaporization source containing stimulable phosphors of an alkaline metal halide base or a material of them onto a substrate, the evaporation is carried out by setting the speed of the evaporation and the temperature of the substrate at the speed K and the temperature T respectively which satisfy the relational expressions (1) and (2) shown below. The relational expression (1): 0.4≤K≤1.2×10<SP>-7</SP>exp (-11.4 (kcal/mol/RT). The relational expression (2): T≤673 [K is the speed of evaporation (μm/min.). T is the temperature (absolute temperature) of the substrate. R is a gas constant]. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a radiation image conversion panel used in a radiation image recording / reproducing method using a stimulable phosphor.

[0002]

2. Description of the Related Art When radiation such as X-rays is irradiated, a part of the radiation energy is absorbed and accumulated, and then, when irradiated with electromagnetic waves (excitation light) such as visible light and infrared rays, the accumulated radiation energy is changed. A stimulable phosphor having a property of emitting light (such as a stimulable phosphor exhibiting stimulated luminescence) is used to apply a test object to a sheet-shaped radiation image conversion panel containing the stimulable phosphor. After the radiation image information of the subject is once stored and recorded by irradiating the transmitted or emitted radiation from the subject, the panel is scanned with excitation light such as laser light and sequentially emitted as emitted light, and the emitted light is emitted. A radiation image recording / reproducing method, which consists of photoelectrically reading and obtaining an image signal, has been widely put into practical use. The panel that has finished reading is erased of the remaining radiation energy, and then prepared and used repeatedly for the next imaging.

A radiation image conversion panel (also referred to as a stimulable phosphor sheet) used in the radiation image recording / reproducing method has a basic structure comprising a support and a phosphor layer provided thereon. However, when the phosphor layer is self-supporting, a support is not always necessary. In addition, a protective layer is usually provided on the upper surface of the phosphor layer (the surface not facing the support) to protect the phosphor layer from chemical alteration or physical impact.

The phosphor layer is composed of a stimulable phosphor and a binder which contains and supports the stimulable phosphor in a dispersed state. The phosphor layer does not include a binder formed by a vapor deposition method or a sintering method. Known are ones composed only of aggregates, ones in which polymer substances are impregnated in the gaps between the aggregates of stimulable phosphors, and the like.

As another method of the above-mentioned radiation image recording / reproducing method, Japanese Patent Laid-Open No. 2001-255610 discloses that the radiation absorbing function and the energy storing function of the conventional stimulable phosphor are separated and at least the stimulable phosphor is used. Radiation image using a combination of a radiation image conversion panel containing (energy storage phosphor) and a phosphor screen containing a phosphor that absorbs radiation and emits light in the ultraviolet to visible region (radiation absorption phosphor) Forming methods have been proposed.
In this method, first, the radiation that has passed through the subject is converted into light in the ultraviolet or visible region by the radiation absorbing phosphor of the screen or panel, and then the light is converted into radiation image information by the energy storing phosphor of the panel. To store and record. Next, the panel is scanned with excitation light to emit emitted light, and the emitted light is photoelectrically read to obtain an image signal. Such a radiation image conversion panel and a fluorescent screen are also included in the present invention.

The radiation image recording / reproducing method (and the radiation image forming method) has a number of excellent advantages as described above, and even the radiation image conversion panel used in this method has as high a sensitivity as possible. It is desired to provide an image having good image quality (sharpness, graininess, etc.).

For the purpose of enhancing sensitivity and image quality, for example, as described in Japanese Patent Publication No. 6-77079, a method of manufacturing a radiation image conversion panel, which comprises forming a phosphor layer by a vapor deposition method. Is proposed. Vapor deposition methods include vapor deposition methods and sputtering methods. For example, the vapor deposition method heats an evaporation source made of a phosphor or its raw material by irradiation of a resistance heater or an electron beam to evaporate and scatter the evaporation source, By depositing the evaporation product on the surface of a substrate such as a metal sheet, a phosphor layer made of columnar crystals of the phosphor is formed.

The phosphor layer formed by the vapor deposition method is
It does not contain a binder and is composed only of the phosphor, and there are voids (cracks) between the columnar crystals of the phosphor.
For this reason, it is possible to improve the entrance efficiency of the excitation light and the extraction efficiency of the emitted light, so that the sensitivity is high, and since it is possible to prevent the excitation light from being scattered in the plane direction, it is possible to provide an image with high sharpness. .

In Japanese Patent No. 3130550, the deposition rate of the phosphor by vapor deposition is generally 0.01 to 1.
000 μm / min, preferably 0.1 to 1
In the range of 00 μm / min, and the speed is 0.01
It is described that if it is lower than μm / min, the phosphor layer formation efficiency is poor, and conversely, if it is higher than 1000 μm / min, it is difficult to control the deposition rate.

[0010]

When the phosphor layer is formed by the vapor deposition method, if the vapor deposition rate is increased while the temperature of the substrate is low, columnar crystals having a good shape are not formed, resulting in deterioration of image quality. It was found that the obtained radiation image was obtained.

As a result of studying the above-mentioned problems, the present inventor has found that when the deposition rate is high, the particles evaporated from the evaporation source and flying onto the substrate are diffused before reaching the proper site of the columnar crystal. It was found that this was due to the particles coming in. Therefore, if the substrate temperature is sufficiently high, the thermal diffusion motion becomes active, so that a columnar crystal having a good shape can be obtained even if the deposition rate is increased.

Further, regarding the shape of the columnar crystal, it was found that there is a specific correlation between the deposition rate and the substrate temperature that promotes thermal diffusion. That is, the inventors have found that the speed at which the flying particles diffuse and reach the appropriate site of the crystal follows the Arrhenius equation, and has reached the present invention.

Accordingly, it is an object of the present invention to provide a method for producing a radiation image conversion panel having a phosphor layer having a good columnar crystal structure and providing a high quality radiation image.

[0014]

According to the present invention, a substance generated by heating an evaporation source containing an alkali metal halide stimulable phosphor having a basic composition formula (I) or a raw material thereof is placed on a substrate. In a method of manufacturing a radiation image conversion panel, which comprises a step of forming a phosphor layer by vapor deposition on a substrate, the vapor deposition rate and the substrate temperature are set to a rate K and a temperature T that satisfy the following relational expressions (1) and (2). A method of manufacturing a radiation image storage panel, which comprises:

The basic composition formula ^{(I): M I X ·} aM II X '2 · bM III X "3: zA ‥‥ (I) [ However, M ^I is the group consisting of Li, Na, K, Rb and Cs Represents at least one alkali metal selected from the group; M ^II is Be, Mg, Ca, Sr, Ba, Ni, C
represents at least one alkaline earth metal or divalent metal selected from the group consisting of u, Zn and Cd; M ^III is S
c, Y, La, Ce, Pr, Nd, Pm, Sm, Eu,
Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, A
represents at least one rare earth element or trivalent metal selected from the group consisting of 1, Ga and In; X, X ′ and X ″
Each represents at least one halogen selected from the group consisting of F, Cl, Br and I; A is Y, Ce,
Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, E
r, Tm, Yb, Lu, Na, Mg, Cu, Ag, Tl
And at least one rare earth element or metal selected from the group consisting of Bi; and a, b and z are 0 ≦ a <0.5, 0 ≦ b <0.5 and 0 <z <1.0, respectively.
Represents a number within the range of

Relational expression (1): 0.4≤K≤1.2 × 10 ^-7 exp (-11.4 (Kcal / mo
l) / R · T) Relational expression (2): T ≦ 673 [where K represents a vapor deposition rate (μm / min), T represents a substrate temperature (absolute temperature), and R represents a gas constant. ].

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION In the manufacturing method of the present invention, it is preferable to heat an evaporation source by irradiating it with an electron beam. It is preferable to perform multi-source vapor deposition using at least an evaporation source containing a base component of an alkali metal halide stimulable phosphor and an evaporation source containing an activator component of the phosphor as an evaporation source. The alkali metal halide-based stimulable phosphor is preferably a europium-activated cesium bromide-based stimulable phosphor.

The method for manufacturing the radiation image storage panel of the present invention will be described in detail below, taking as an example the case where the phosphor layer is formed by an electron beam evaporation method which is one of the evaporation methods.

The substrate for forming the vapor-deposited film usually doubles as a support for the radiation image conversion panel, and can be arbitrarily selected from materials known as a support for conventional radiation image conversion panels. Preferred substrates are a quartz glass sheet, a sapphire glass sheet; a metal sheet made of aluminum, iron, tin, chromium or the like; a resin sheet made of aramid or the like. In a known radiation image conversion panel, in order to improve sensitivity or image quality (sharpness, graininess) as a panel, a light reflecting layer made of a light reflecting material such as titanium dioxide, or a light absorbing material such as carbon black. It is known to provide a light absorption layer and the like. The substrate used in the present invention can also be provided with these various layers, and their configuration can be arbitrarily selected according to the desired purpose and application of the radiation image conversion panel. Further, for the purpose of enhancing the columnar crystallinity of the vapor deposition film, the surface of the substrate on the side where the vapor deposition film is formed (an undercoat layer (adhesion imparting layer) on the surface of the substrate, an auxiliary layer such as a light reflecting layer or a light absorbing layer When it is provided, it may be the surface of these auxiliary layers), and minute irregularities may be formed.

[0020] As the phosphor, the basic formula ^{(I): M I X ·} aM II X '2 · bM III X "3: zA ‥‥ alkali metal halide stimulable phosphor represented by (I) However, M ^I represents at least one alkali metal selected from the group consisting of Li, Na, K, Rb and Cs, and M ^II represents Be, Mg, Ca, Sr, Ba,
Represents at least one alkaline earth metal or divalent metal selected from the group consisting of Ni, Cu, Zn and Cd, and M
^III is Sc, Y, La, Ce, Pr, Nd, Pm, S
m, Eu, Gd, Tb, Dy, Ho, Er, Tm, Y
b, Lu, Al, Ga and In representing at least one rare earth element or trivalent metal selected from the group consisting of In, and A represents Y, Ce, Pr, Nd, Sm, Eu, Gd and T.
b, Dy, Ho, Er, Tm, Yb, Lu, Na, M
It represents at least one rare earth element or metal selected from the group consisting of g, Cu, Ag, Tl and Bi. X, X '
And X ″ each represent at least one halogen selected from the group consisting of F, Cl, Br and I. a,
b and z are 0 ≦ a <0.5, 0 ≦ b <0.
5 represents a numerical value within the range of 0 <z <1.0.

It is preferable that M ^I in the basic composition formula (I) contains at least Cs. X preferably contains at least Br. It is particularly preferable that A is Eu or Bi. Further, in the basic composition formula (I), if necessary, aluminum oxide,
A metal oxide such as silicon dioxide or zirconium oxide may be added as an additive in an amount of 0.5 mol or less with respect to 1 mol of M ^I.

When the phosphor layer is formed by multi-source vapor deposition (co-deposition), at least two evaporation sources, one containing the matrix component of the stimulable phosphor and the other containing the activator component, are used. Prepare individual evaporation sources. Multi-source vapor deposition is preferable because the vapor deposition rates of the matrix component of the phosphor and the activator component can be controlled when the vapor pressures thereof are largely different. Each evaporation source, depending on the composition of the desired phosphor,
It may be composed of only the matrix component and the activator component of the phosphor, or may be a mixture with an additive component and the like. Further, the number of evaporation sources is not limited to two, and for example, three or more may be added by additionally adding evaporation sources made of additive components.

The matrix component of the phosphor may be the compound itself constituting the matrix, or a mixture of two or more raw materials which can react to form a matrix compound. The activator component is generally a compound containing an activator element, and for example, a halide or oxide of the activator element is used.

When the activator is Eu, the molar ratio of the Eu ²⁺ compound to the Eu compound as the activator component is preferably 70% or more. In general, Eu compounds are Eu ²⁺
And Eu ³⁺ are mixed and contained, but the desired stimulated emission (or even instantaneous emission) is emitted from the phosphor having Eu ²⁺ as the activator. Eu compound is E
uBr _x is preferred, in which case x is 2.
It is preferable that the numerical value is within a range of 0 ≦ x ≦ 2.3.
It is desirable that x is 2.0, but if it is made to approach 2.0, oxygen is likely to be mixed. Therefore, in practice, x is stable in the vicinity of 2.2 and the ratio of Br is relatively high.

The evaporation source preferably has a water content of 0.5% by weight or less. Especially when the phosphor matrix component or activator component serving as the evaporation source is hygroscopic like CsBr and EuBr, it is important to suppress the water content to such a low value in order to prevent bumping. Is. For dehydration of the evaporation source, 100 to 300 of the above phosphor components are decompressed.
It can be carried out by heat treatment in the temperature range of ° C, or by heating and melting for several tens of minutes to several hours at a temperature not lower than the melting point of the component in a moisture-free atmosphere such as a nitrogen atmosphere.

The relative density of the evaporation source is 80% or more, 98
% Or less, more preferably 90%
As a result, it is 96% or less. Here, the relative density means the ratio of the actual density of the evaporation source to the density specific to the phosphor or its raw material. For example, when the relative density is 80% or more, CsBr ≧ 3.5 g / cm ³ and EuBr ₂ ≧ 4.4 g.
/ Cm ³ is meant. If the evaporation source is in a powder state with a low relative density, it may cause inconveniences such as powder scattering during vapor deposition, or the film thickness of the vapor deposition film may not be uniform because it does not evaporate uniformly from the surface of the evaporation source. Or Therefore, in order to realize stable vapor deposition, it is desirable that the density of the evaporation source is high to some extent. To obtain the above relative density, powder is generally 20M
It is pressed under a pressure of Pa or higher, or is heated and melted at a temperature equal to or higher than the melting point to form a tablet. However, the evaporation source does not necessarily have to be tablet-shaped.

Further, the evaporation source, especially the evaporation source containing the matrix component of the phosphor, has an alkali metal impurity content (that is, an alkali metal other than the constituent elements of the phosphor) of 10 ppm.
And the content of alkaline earth metal impurities (that is, alkaline earth metals other than the constituent elements of the phosphor) is preferably 1 ppm or less. Such an evaporation source can be prepared by using a raw material having a low content of impurities such as an alkali metal or an alkaline earth metal. As a result, a vapor-deposited film containing less impurities can be formed, and the vapor-deposited film thus formed has an increased light emission amount.

The evaporation source and the substrate are placed in a vapor deposition apparatus, and the inside of the apparatus is evacuated to a vacuum degree of about 1 × 10 ^-5 to 1 × 10 ^-2 Pa. At this time, an inert gas such as Ar gas or Ne gas may be introduced while maintaining the degree of vacuum at this level. In addition, the water pressure in the atmosphere in the device is adjusted to 7.0 × 10 ⁻³ P by using a combination of a cryopump or a diffusion pump and a cold trap.
It is preferably a or less.

Next, an electron beam is generated from each of the two electron guns to irradiate each evaporation source. At this time, the acceleration voltage of the electron beam is preferably set to 1.5 kV or more and 5.0 kV or less. Then, the evaporation rate of each evaporation source is controlled as follows by adjusting the acceleration voltage of each electron beam. At the same time, the concentrations of additive components such as activators are adjusted.

It was found that the speed k at which the particles evaporated from the evaporation source by the electron beam irradiation and flying on the substrate reach the appropriate site of the crystal by diffusion follow the Arrhenius equation below.

K = Aexp (−Ea / R · T) (3) [where k represents a rate constant, T represents an absolute temperature, and
A and Ea each represent a constant unique to the reaction system, and R represents a gas constant.]

From the experiment, the deposition rate of the phosphor, that is, the vapor deposition rate K was A = 1.2 × 10 ⁻⁷ and Ea = 11.4 (kcal / mol) in the above Arrhenius equation.
It was found that a vapor deposition film having a good columnar crystal shape can be obtained when the speed is not more than k. On the other hand, it is appropriate that the vapor deposition rate K is 0.4 μm / min or more from the viewpoint of the formation efficiency of the vapor deposited film. Therefore, in the present invention, the vapor deposition rate K is a rate that satisfies the following relational expression (1).

Relational expression (1): 0.4 ≦ K ≦ 1.2 × 10 ⁻⁷ exp (−11.4 (Kcal / mo
l) / R · T) [where K represents the deposition rate (μm / min), T represents the substrate temperature (absolute temperature), and R represents the gas constant].

Further, in the present invention, it is general to heat the substrate during vapor deposition. The substrate is usually heated by using radiant heat from a heater. It is suitable that the heating temperature T of the substrate is a temperature that satisfies the above relational expression (1) and that satisfies the following relational expression (2) from the viewpoint of operability and the like.

Relational expression (2): T ≦ 673

FIG. 1 is a graph showing the relationship between the substrate temperature T and the vapor deposition rate K. In FIG. 1, the solid line 1 represents the equation K =
1.2 × 10 ^-7 exp (-11.4 (Kcal / mol) / RT)
, The dotted line 2 is the straight line representing the equation K = 0.4, and the dotted line 3 is the straight line representing T = 673 (300 ° C.).

Therefore, in the present invention, the vapor deposition rate K and the substrate temperature T must exist within the region surrounded by these lines 1 to 3 (hatched portion). In practice, the vapor deposition rate K is determined according to the substrate temperature T so that it falls within the region of this graph.

Upon irradiation with an electron beam, the matrix component and activator component of the stimulable phosphor, which is the evaporation source, are heated to evaporate and scatter, and react to form a phosphor, and at the same time the substrate surface is formed. accumulate. It is also possible to form the phosphor layer of two or more layers by performing electron beam irradiation in several times.
Further, the phosphor layer may be subjected to a heat treatment (annealing treatment) after completion of the vapor deposition.

In the case of one-source vapor deposition (pseudo-one-source vapor deposition), one vaporization source containing the phosphor matrix component and the activator component separated in the direction perpendicular to the vaporization flow (direction parallel to the substrate) is used. It is preferable to prepare. During vapor deposition, one electron beam is used to control the time (residence time) for irradiating each of the matrix component region and the activator component region of the evaporation source with an electron beam, thereby stimulating the uniform composition. A vapor-deposited film made of a fluorescent substance can be formed. Alternatively, it may be a unitary vapor deposition using the stimulable phosphor itself as an evaporation source.

Alternatively, before forming the vapor-deposited film made of the stimulable phosphor, the vapor-deposited film made of only the matrix of the phosphor may be formed. This makes it possible to obtain a vapor-deposited film having better columnar crystallinity. Additives such as an activator in the vapor-deposited film made of the phosphor are diffused in the vapor-deposited film made of the phosphor matrix by the heating during the vapor deposition and / or the heat treatment after the vapor deposition. Is not always clear.

In this way, a layer is obtained in which the columnar crystals of the stimulable phosphor are grown approximately in the thickness direction. The layer thickness of the phosphor layer is usually in the range of 50 to 1000 μm, preferably 200 μm to 700 mm.

In the present invention, the vapor deposition method is not limited to the electron beam vapor deposition method described above, and other known methods such as a resistance heating method can be used. Further, the substrate does not necessarily have to double as a support for the radiation image conversion panel, and after the phosphor layer is formed, the phosphor layer is peeled off from the substrate,
It is also possible to use a method in which a phosphor layer is provided on the support by bonding the support separately prepared using an adhesive or the like. Alternatively, the support (substrate) may not be attached to the phosphor layer.

It is desirable to provide a protective layer on the surface of the phosphor layer for the convenience of transportation and handling of the radiation image conversion panel and for avoiding a change in characteristics. The protective layer has almost no effect on the incidence of excitation light or the emission of emitted light,
It is desirable to be transparent, and it is chemically stable, highly moisture-proof, and has high physical strength so that the radiation image conversion panel can be sufficiently protected from external physical impact and chemical influences. It is desirable to have.

As the protective layer, a solution prepared by dissolving a transparent organic polymer substance such as a cellulose derivative, polymethylmethacrylate, or an organic solvent-soluble fluororesin in an appropriate solvent is applied on the phosphor layer. Or a sheet formed by separately forming a protective layer forming sheet such as an organic polymer film such as polyethylene terephthalate or a transparent glass plate and providing it on the surface of the phosphor layer with an appropriate adhesive. Alternatively, an inorganic compound deposited on the phosphor layer by vapor deposition or the like is used. Further, in the protective layer, various additives such as light-scattering fine particles of magnesium oxide, zinc oxide, titanium dioxide, alumina, etc., sliding agents such as perfluoroolefin resin powder, silicone resin powder, etc., and crosslinking agents such as polyisocyanate etc. May be dispersedly contained. The thickness of the protective layer is generally in the range of about 0.1 to 20 μm when it is made of a polymeric substance, and 100 to 100 when it is made of an inorganic compound such as glass.
It is in the range of 1000 μm.

The surface of the protective layer may be further provided with a fluororesin coating layer in order to enhance the stain resistance of the protective layer. The fluororesin coating layer can be formed by applying a fluororesin solution prepared by dissolving (or dispersing) a fluororesin in an organic solvent onto the surface of the protective layer and drying.
Although the fluororesin may be used alone, it is usually used as a mixture of the fluororesin and a resin having high film forming property. Further, an oligomer having a polysiloxane skeleton or an oligomer having a perfluoroalkyl group can be used together. The fluororesin coating layer may be filled with a fine particle filler in order to reduce interference unevenness and further improve the quality of a radiation image. The layer thickness of the fluororesin coating layer is usually in the range of 0.5 μm to 20 μm. In forming the fluororesin coating layer, an additive component such as a cross-linking agent, a hardener, an anti-yellowing agent, etc. can be used. In particular, the addition of the crosslinking agent is advantageous for improving the durability of the fluororesin coating layer.

Although the radiation image storage panel of the present invention is obtained as described above, the panel construction of the present invention may include various known variations. For example, at least one of the layers may be colored with a coloring agent that absorbs excitation light but not stimulated emission light for the purpose of improving the sharpness of the obtained image.

[0047]

EXAMPLES [Example 1] (1) Raw material As a raw material, cesium bromide (CsB) having a purity of 4N or more was used.
r), and europium bromide (EuB) having a purity of 3N or more.
r _x , x = 2.2) was used. As a result of analyzing trace elements in each raw material by ICP-MS method (inductively coupled high frequency plasma spectroscopy-mass spectrometry), alkali metals other than Cs in CsBr (Li, Na, K, Rb) are 10 p each.
pm or less, alkaline earth metal (Mg, Ca, S
Other elements such as r and Ba) were 2 ppm or less. Further, each of the rare earth elements other than Eu in EuBr _x is 20 p
pm or less, and other elements were 10 ppm or less.
Since these raw materials have high hygroscopicity, they were stored in a desiccator which kept a dry atmosphere with a dew point of −20 ° C. or lower and taken out just before use.

(2) Preparation of CsBr evaporation source 75 g of CsBr powder was put into a powder molding die (internal diameter: 35 mm) made of zirconia, and a powder mold press molding machine (table press TB-5 type, NP System Co., Ltd.).
It was pressed with a pressure of 50 MPa with a pressure sensor (made by Mfg. Co., Ltd.) to form tablets (diameter: 35 mm, thickness: 20 mm). At this time, the pressure applied to the CsBr powder was about 40 MPa. Next, a temperature of 200 is applied to this tablet with a vacuum dryer.
A vacuum drying treatment was carried out at 0 ° C. for 2 hours. The obtained tablet had a density of 3.9 g / cm ³ and a water content of 0.3% by weight.

(3) EuBr_xPreparation of evaporation source EuBr_x(X = 2.2) 25 g of powder is zirconia-milled
Put the powder into a powder molding die (inner diameter: 25 mm) and press the powder mold.
Presses at a pressure of 50MPa using a less molding machine and tablets
(Diameter: 25 mm, thickness: 10 mm). this
When EuBr _xThe pressure applied to the powder is about 80 MPa
there were. Next, the temperature of this tablet is 2 using a vacuum dryer.
A vacuum drying treatment was performed at 00 ° C. for 2 hours. Got tab
Let's density is 5.1g / cm³And the water content is 0.
It was 5% by weight.

(4) Formation of Phosphor Layer As a support, alkaline cleaning, pure water cleaning, and I
A synthetic quartz substrate that had been washed with PA (isopropanol) was prepared, and this was placed on a substrate holder in a vapor deposition apparatus.
After arranging the CsBr evaporation source and the EuBr _x evaporation source at predetermined positions in the apparatus, the apparatus is evacuated to 1 × 10 ⁻³ P
The degree of vacuum of a was set. At this time, a combination of a rotary pump, a mechanical booster, and a turbo molecular pump was used as a vacuum exhaust device. Next, the quartz substrate was heated to 200 ° C. with a sheath heater located on the side opposite to the vapor deposition surface of the substrate. Acceleration voltage 4.0k with electron gun for each evaporation source
A CsBr: Eu stimulable phosphor was deposited by irradiating a V electron beam to co-evaporate. At this time, by adjusting the emission current of each electron gun, Eu /
The Cs molarity ratio was 0.003 / 1 and deposited at a rate of 4 μm / min. At the time of vapor deposition, the atmospheric gas in the vapor deposition apparatus was analyzed and calculated using a mass spectrometer, and the moisture pressure in the vapor deposition atmosphere was 4 × 10 ⁻³ Pa.
Met.

After the completion of vapor deposition, the inside of the apparatus was returned to atmospheric pressure, and then the substrate was taken out from the apparatus. On the substrate, a phosphor layer (layer thickness: about 400 μm, area: 10 cm × 10 cm) having a structure in which columnar crystals of phosphor were densely packed in a substantially vertical direction was formed. Thus, the radiation image storage panel according to the present invention comprising the support and the phosphor layer was produced by co-evaporation.

Example 2 (4) The phosphor layer was formed on the substrate in the same manner as in Example 1 except that the vapor deposition rate was changed to 0.4 μm / min in the formation of the phosphor layer. A phosphor layer having a structure in which columnar crystals were densely forested in a substantially vertical direction was formed. Thus, the radiation image storage panel according to the present invention, which comprises the support and the phosphor layer, was manufactured.

[Third Embodiment] The columnar crystal of the phosphor was formed on the substrate in the same manner as in the first embodiment except that the vapor deposition rate was changed to 16 μm / min in the formation of the phosphor layer (4) of the first embodiment. Formed a phosphor layer having a densely forested structure in a substantially vertical direction. Thus, the radiation image storage panel according to the present invention, which comprises the support and the phosphor layer, was manufactured.

[Comparative Example 1] Columnar crystals of the phosphor were formed on the substrate in the same manner as in Example 1 except that the substrate temperature was changed to 30 ° C in the formation of the phosphor layer (4) of Example 1. A phosphor layer having a dense forest structure was formed almost vertically.
In this way, a comparative radiation image conversion panel comprising a support and a phosphor layer was produced.

[Comparative Example 2] Columnar crystals of the phosphor were formed on the substrate in the same manner as in Example 1 except that the substrate temperature was changed to 100 ° C in the formation of the phosphor layer (4) in Example 1. A phosphor layer having a dense forest structure was formed almost vertically. In this way, a comparative radiation image conversion panel comprising a support and a phosphor layer was produced.

[Comparative Example 3] In the formation of the phosphor layer (4) of Example 1, the substrate temperature was 30 ° C. and the vapor deposition rate was 0.02 μm /
A phosphor layer having a structure in which columnar crystals of phosphor were densely forested in a substantially vertical direction was formed on the substrate in the same manner as in Example 1 except that the content was changed. In this way, a comparative radiation image conversion panel comprising a support and a phosphor layer was produced.

[Performance Evaluation 1 of Radiation Image Conversion Panel] The shape of the columnar crystals of the phosphor layer of each radiation image conversion panel was evaluated. The phosphor layer of the radiation image conversion panel is cut along with the support in the thickness direction, and is covered with gold (thickness: 300 Å) by ion sputtering to prevent charge-up, and then the scanning electron microscope (JSM-540).
The cut surface of the phosphor layer was observed using a 0 type, manufactured by JEOL Ltd.). The columnarity was determined based on the shape of the columnar crystal (column diameter, presence or absence of knots, etc.). The obtained results are summarized in Table 1 and FIG.

[0058]

[Table 1]                                 Table 1 ────────────────────────────────────   Example Substrate temperature Deposition rate Columnar crystal shape Columnarity                 (℃) (μm / min) ────────────────────────────────────   Example 1 200 4 5-10 μm diameter good   Example 2 200 0.4 10 μm diameter good   Example 3 200 16 5-10 μm diameter somewhat good                                         There is some knot ────────────────────────────────────   Comparative Example 1 30 4 2 to 10 μm diameter defective                                         Fusion in the lateral direction, many knots   Comparative Example 2 100 4 5-10 μm diameter granular defect   Comparative Example 3 30 0.02 2 to 10 μm Diameter somewhat good                                         There is some knot ────────────────────────────────────

FIG. 2 is a graph showing the relationship between the substrate temperature T and the vapor deposition rate K, and the solid line 1 is the formula K = 1.2 × 10 ⁻⁷ ex
p (-11.4 (Kcal / mol) / R · T) is a curve, the shaded area is the allowable range of the present invention with respect to the substrate temperature and the deposition rate, and the black circles represent Examples 1 to 3, White circles represent Comparative Examples 1 to 3.

As is clear from the results shown in Table 1 and FIG. 2, the radiation image conversion panel obtained by performing vapor deposition at a substrate temperature and a vapor deposition rate within the permissible range of the present invention (Examples 1 to 1).
In 3), the shape of the columnar crystals of the phosphor layer was good. On the other hand, in the radiation image conversion panels (Comparative Examples 1 and 2) obtained by performing vapor deposition at a combination of the substrate temperature and the vapor deposition rate that deviate from the permissible range (solid line 1) of the present invention, columnar crystals are fused to each other. However, the columnarity was poor because it became granular. In Comparative Example 3, the combination of the substrate temperature and the vapor deposition rate was inside the solid line 1 and the columnarity was good, but the vapor deposition film formation efficiency was too low to be suitable for practical use.

Example 4 (1) Raw Material The same raw material as in Example 1 was used. (2) Preparation of CsBr evaporation source In the same manner as in Example 1, CsBr tablets were prepared. (3) Preparation of EuBr _x evaporation source EuBr _x (x = 2.2) tablets were prepared in the same manner as in Example 1.

(4) Formation of Phosphor Layer As a support, a glass substrate (diameter φ of each protrusion) formed by patterning minute protrusions on one surface in a regular array
= 2 μm, height h = 2 μm, distance d between projections d = 3 μm)
Was prepared and sequentially subjected to alkali cleaning, pure water cleaning, and IPA (isopropanol) cleaning. The glass substrate was placed on the substrate holder in the vapor deposition device so that the patterned surface became the vapor deposition surface. After arranging the CsBr evaporation source and the EuBr _x evaporation source at predetermined positions in the apparatus, the inside of the apparatus was evacuated to a vacuum degree of 1 × 10 ⁻³ Pa.
At this time, a combination of a rotary pump, a mechanical booster, and a turbo molecular pump was used as a vacuum exhaust device. Next, the glass substrate was heated to 300 ° C. with a sheath heater located on the side opposite to the vapor deposition surface of the substrate. Each evaporation source was irradiated with an electron beam with an accelerating voltage of 4.0 kV by an electron gun to co-evaporate to deposit a CsBr: Eu stimulable phosphor. At this time, the emission current of each electron gun was adjusted so that the Eu / Cs molar concentration ratio in the stimulable phosphor was 0.003 / 1, and the phosphor was deposited at a rate of 5 μm / min. At the time of vapor deposition, the atmospheric gas in the vapor deposition apparatus was analyzed and calculated using a mass spectrometer, and the water pressure in the vapor deposition atmosphere was 4 × 10 ⁻³ Pa.

After completion of vapor deposition, the inside of the apparatus was returned to atmospheric pressure, and then the substrate was taken out from the apparatus. On the substrate, a phosphor layer (layer thickness: about 400 μm, area: 10 cm × 10 cm) having a structure in which columnar crystals of phosphor were densely packed in a substantially vertical direction was formed. Thus, the radiation image storage panel according to the present invention comprising the support and the phosphor layer was produced by co-evaporation.

[Examples 5 to 10] In the formation of the phosphor layer (4) of Example 4, except that the patterned substrate, the substrate temperature and / or the vapor deposition rate were changed as shown in Table 2. In the same manner as in Example 4, a phosphor layer having a structure in which columnar crystals of the phosphor were densely forested in a substantially vertical direction was formed on the substrate. In this way, various radiation image conversion panels according to the present invention, which consist of the support and the phosphor layer, were manufactured.

[Performance Evaluation 2 of Radiation Image Conversion Panel] The shape of the columnar crystals of the phosphor layer of each obtained radiation image conversion panel was evaluated in the same manner as described above. The obtained results are summarized in Table 2 and FIGS. 2 and 3.

[0066]

[Table 2]                                 Table 2 ────────────────────────────────────  Example Substrate pattern Substrate temperature Deposition rate Columnarity of columnar crystals              (μm) (℃) (μm / min) Shape (μm diameter)             φ d h ──────────────────────────────────── Example 4 2 3 2 300 5 3-6 Very good Example 5 2 3 2 300 2.5 3-6 Very good Example 6 5 7 5 300 1.25 5-10 Good Example 7 5 7 5 300 0.5 5-10 Good Example 8 2 3 2 200 5 3-6 Good Example 9 5 7 5 150 5 5-10 Good Example 10 2 3 2 100 1.25 3-6 Good ────────────────────────────────────

FIG. 2 is a graph showing the relationship between the substrate temperature T and the vapor deposition rate K. The shaded area is the permissible range of the present invention with respect to the substrate temperature and the vapor deposition rate, and the white rhombuses show the results of Examples 4 to 4.
Represents 10.

FIG. 3 is a partially enlarged sectional view in the thickness direction showing the columnar crystal structure of the phosphor layer of the radiation image storage panel according to the present invention (Example 5).

As is clear from the results of Table 2 and FIGS. 2 and 3, the radiation image conversion panel obtained by performing vapor deposition using the patterned substrate at the substrate temperature and the vapor deposition rate within the permissible range of the present invention (implementation) In Examples 4 to 10), the columnar crystals of the phosphor layer had a small column diameter, and the shape was even better.

[0070]

According to the manufacturing method of the present invention, a phosphor layer having a good columnar crystal structure can be formed by applying the substrate temperature and the vapor deposition rate during vapor deposition in combination within a specific range. it can. This makes it possible to obtain a radiation image conversion panel that gives a high-quality radiation image.

[Brief description of drawings]

FIG. 1 is a graph showing a relationship between a substrate temperature T and a vapor deposition rate K.

FIG. 2 is a graph showing a relationship between a substrate temperature T and a vapor deposition rate K.

FIG. 3 is a partially enlarged cross-sectional view of a phosphor layer of the radiation image storage panel according to the present invention.

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) C09K 11/64 C09K 11/64 11/85 11/85 C23C 14/06 C23C 14/06 G G01T 1/00 G01T 1 / 00 B (72) Inventor Atsunori Takasu 798, Miyadai, Kaisei-cho, Ashigarashie-gun, Kanagawa Photo film Co., Ltd. (72) Inventor, Yuji Isada 798, Miyadai, Kaisei-cho, Ashigagami-gun, Kanagawa F-term, Fujishi film Co., Ltd. (Reference) 2G083 AA03 BB01 CC03 DD02 DD11 DD14 DD15 4H001 CA04 CA08 CF01 XA00 XA03 XA04 XA09 XA11 XA12 XA13 XA17 XA19 XA20 XA21 XA28 XA29 XA30 XA31 XA31 XA31 XA38 XA38 XA39 XA38 XA38 XA38 BA42 BB08 BC07 BD00 CA01 DB05 DB08 DB14 DB21

Claims (4)

[Claims] 1. A phosphor layer is formed by depositing a substance generated by heating an evaporation source containing an alkali metal halide stimulable phosphor having a basic composition formula (I) or a raw material thereof on a substrate. In the method of manufacturing a radiation image conversion panel including the step of
Method for manufacturing a radiation image conversion panel, characterized in that vapor deposition is performed at a rate K and a temperature T that satisfy the following relational expressions (1) and (2): Basic composition formula (I): M ^I X.a M ^II X ' ₂ · bM ^III X ″ ₃ : zA (I) [wherein M ^I represents at least one alkali metal selected from the group consisting of Li, Na, K, Rb and Cs; M ^II represents Be, Mg, Ca, Sr, Ba, Ni, C
represents at least one alkaline earth metal or divalent metal selected from the group consisting of u, Zn and Cd; M ^III is S
c, Y, La, Ce, Pr, Nd, Pm, Sm, Eu,
Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, A
represents at least one rare earth element or trivalent metal selected from the group consisting of 1, Ga and In; X, X ′ and X ″
Each represents at least one halogen selected from the group consisting of F, Cl, Br and I; A is Y, Ce,
Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, E
r, Tm, Yb, Lu, Na, Mg, Cu, Ag, Tl
And at least one rare earth element or metal selected from the group consisting of Bi; and a, b and z are 0 ≦ a <0.5, 0 ≦ b <0.5 and 0 <z <1.0, respectively.
Represents a numerical value within the range of]] Relational expression (1): 0.4 ≦ K ≦ 1.2 × 10 ⁻⁷ exp (−11.4 (Kcal / mo
l) / R · T) Relational expression (2): T ≦ 673 [where K represents a vapor deposition rate (μm / min), T represents a substrate temperature (absolute temperature), and R represents a gas constant. ] 2. The method of manufacturing a radiation image conversion panel according to claim 1, wherein heating is performed by irradiating an evaporation source with an electron beam. 3. Multi-source vapor deposition is carried out using, as an evaporation source, at least an evaporation source containing a matrix component of an alkali metal halide stimulable phosphor and an evaporation source containing an activator component of the phosphor. 1. The method for manufacturing the radiation image storage panel according to 1 or 2. 4. The radiation image storage panel according to claim 1, wherein the alkali metal halide stimulable phosphor is a europium activated cesium bromide stimulable phosphor. Production method.