JP2789194B2 - Phosphor deposition equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phosphor vapor deposition apparatus, and more particularly, to a phosphor vapor deposition apparatus capable of forming a phosphor layer having a substantially constant layer thickness over a large area. It is about.

[Conventional technology]

Phosphors have been studied for a long time, expanding the scope of search for fluorescent substances, and as the elucidation of the light emission mechanism and emission characteristics of the fluorescent substances progresses, fluorescent lamps, X-ray fluorescent screens or CRTs, etc. Application fields have been opened up over a wide range such as for displays.

In the use of these phosphors, a phosphor powder obtained by a general phosphor synthesis method including a firing step is sufficiently dispersed in a solvent containing a binder, and then coated on a glass tube or other support. I do. After that, it is used for various applications by drying it to remove the solvent and forming a phosphor layer containing a binder.

Further, the dissociation properties of the phosphor afterglow, ie, the quenching properties and stimulability, have been studied in detail. In particular, the stimulability (longer afterglow of a crystalline phosphor is longer than that of the phosphor). Focusing on the phenomenon in which energy is emitted from the phosphor that has stored light when irradiated with light of a wavelength and the brightness of the afterglow sharply increases), the use of the stimulable phosphor as an intermediate recording medium for radiation images has been opened up. Further, the progress of adaptation to a recording medium, such as the improvement of the stimulable luminescence intensity, the improvement of the rectangular response to the stimulating light of the stimulable luminescence, or the development of a stimulable phosphor has been accelerated.

The intermediate recording medium absorbs radiation transmitted through the subject into a fluorescent material, and then excites the fluorescent material with, for example, light or heat energy, so that the fluorescent material absorbs the radiation energy accumulated by the absorption. , And detect it to form an image.

Specifically, for example, U.S. Pat.
No. 5-12144 discloses a radiation image conversion method using a stimulable phosphor and using visible light or infrared light as stimulating excitation light. In this method, a radiation image conversion panel having a stimulable phosphor layer formed on a support is used. A latent image is formed by accumulating radiation energy corresponding to the radiation transmittance, and thereafter, the stimulable phosphor layer is scanned with stimulating excitation light to emit the accumulated radiation energy of each part and emit light. And an image is obtained by an optical signal based on the intensity of the light. Thus, the final image may be reproduced as a hard copy or reproduced on a CRT.

However, in general, a radiant image conversion panel having a stimulable phosphor layer has a particle size of 1 μm to 30 μm similar to that of the general phosphor.
A dispersion containing a granular photostimulable phosphor layer of about μm and an organic binder is applied to a support (or a protective layer) and dried, so that the packing density of the photostimulable phosphor is low. (Approximately 50% filling factor) Therefore, it was necessary to increase the thickness of the stimulable phosphor layer in order to sufficiently increase the radiation sensitivity.

On the other hand, the sharpness at the time of the radiation image conversion tends to be higher as the thickness of the stimulable phosphor layer of the radiation image conversion panel is thinner. It was necessary to make the conductive phosphor layer thinner.

That is, the conventional radiation image conversion panel is produced by a certain degree of mutual sacrifice between the sensitivity and the image granularity and the image sharpness which show a completely opposite tendency with respect to the thickness of the stimulable phosphor layer. It has been.

In such a situation, some means have been devised for improving the sharpness of a radiographic image. For example, a method of mixing a white powder in the stimulable phosphor layer of the radiation image conversion panel described in JP-A-55-146447, or the stimulability of the radiation image conversion panel described in JP-A-55-163500. There is a method of coloring the phosphor layer so that the average reflectance in the stimulating phosphor wavelength region is smaller than the average reflectance in the stimulating emission wavelength region of the stimulable phosphor layer. However, these methods are not preferable because the improvement in sharpness inevitably lowers the sensitivity.

By the way, in recent years, with the development of vacuum technology and thin film formation technology using vacuum technology, attempts have been made to form a phosphor layer using a vapor deposition method, and some of them have already been put into practical use. Examples of the phosphor layer formed by the vapor deposition method include an X-ray image intensifier using a CsI: Na phosphor layer and a thin-film EL (electroluminescence) panel using a ZnS: Mn phosphor layer. Are known. The present applicant has proposed a radiation image conversion panel comprising a stimulable phosphor layer containing no binder (binder) in Japanese Patent Application Laid-Open No. 61-73100.

Unlike conventional phosphor layers formed by these vapor deposition methods, the phosphor layer is formed in a vacuum, so that the amount of mixed impurities is extremely small, and as a result, the emission intensity is high and the dispersion is high. It is characterized in that a phosphor layer with a small number of phosphors is obtained, and that a substance other than the phosphor such as a binder is not contained, and the phosphor packing density is almost 100%, so that light emission can be effectively used. In particular, in the case of a radiation image conversion panel, since the stimulable phosphor layer does not contain a binder, the filling rate of the stimulable phosphor layer is significantly improved, and the stimulable phosphor layer is stimulable. The directivity of the excitation light and the stimulated emission is improved, and the sensitivity of the radiation image conversion panel to radiation and the granularity of the image are improved, and the sharpness of the image is also improved.

The `` improvement of directivity '' is derived from fine columnar crystals formed in the process of vapor phase deposition of the stimulable phosphor layer,
It has a significant effect on the resulting image. But,
In general, when these phosphor layers are formed by a vapor deposition method, a sputtering method, or the like utilizing a vapor deposition method, a variation in the thickness of the phosphor layers becomes a serious problem. Regarding evaporation from point evaporation sources (Here, t ₀ and t respectively represent the center of the support surface separated from the evaporation source by the distance h and the layer thickness at the position of the distance x from the center of the support surface.) The distance from the evaporation source is h = 40 cm, and the size of the support is 30 cm × 30 cm.
Then, the layer thickness at the peripheral portion of the support surface with respect to the center of the support surface is 82%, which is 18% smaller than the center of the support surface.

Conventionally, in vapor deposition on a large-area support, operations such as increasing the distance between the evaporation source and the support or rotating the support have been performed in order to make the layer thickness uniform.

[Problems to be solved by the invention]

However, in operations such as increasing the distance between these evaporation sources and the support or rotating the support, the phosphor layer formation efficiency, that is, Was significantly worse, and required a sufficiently large vacuum chamber for the support.

In addition, it was difficult to completely improve the disadvantage that the thickness of the layer increased around the periphery of the support, and the thickness of the layer further increased as the deposition area increased.

This variation in the thickness of the phosphor layer caused a variation in the light emission intensity, which not only deteriorated the reproducibility when reproducing the image, but also greatly affected the sharpness and granularity of the image. In particular, 389 mm x 445 for radiation image conversion panels
Since a panel having a size of mm is used, it is extremely difficult to keep the thickness of the stimulable phosphor layer formed by the conventional method substantially constant over the entire surface of the panel.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide a phosphor vapor deposition apparatus in which the thickness of a phosphor layer is substantially constant over a large area. Also,
It is another object of the present invention to provide a phosphor vapor deposition apparatus having high phosphor layer formation efficiency and high productivity.

[Means for solving the problem]

To achieve the above object, the present invention provides an evaporation source,
A regulating member that regulates an intersection angle at which a steam flow from the evaporation source having a slit is incident on the support body surface, between the support and the evaporation source that move relatively to the evaporation source, The slit has a width in a direction orthogonal to the transport direction of the support, which is equal to or greater than a width of the support in a direction orthogonal to the transport direction of the support, and a width of the slit in the transport direction of the support. It is characterized in that it is narrower at the center than at the ends.

Next, the present invention will be described with reference to the accompanying drawings. FIG. 1 (a) is an explanatory view of the relative position and attitude of the linear evaporation source and the support and the movement of the support.

In this figure, 11 is a linear evaporation source and 13 is a support.
The linear evaporation source 11 is penetrated by a straight line a in the length direction. The linear evaporation source 11 may be a multi-source evaporation source skewed by a straight line a.

The plane A including the straight line a intersects with the plane C of the support 13 by forming an intersection line b. The straight line a and the intersection line b are parallel. A plane B parallel to the intersection line b intersects with the plane A at an intersection angle θ, and a surface C of the support 13 contacts the plane B at a tangent line c.

Thus, the support 13 is movable in two directions (reciprocation) in a direction substantially perpendicular to the intersection line b (arrow in the figure). In addition,
The plane B may be a plane B ′ that is in contact with the support surface C at the intersection line b.

The intersection angle θ is practically determined by the shape and position of the streamline of the steam flow and the shape of the streamline regulating member, but is preferably substantially a right angle.

As shown in FIGS. 1 (b) and (c), the support 13 is adapted to a steam flow (indicated by a broken line) 16 emanating from the linear evaporation source 11,
Any rigid sheet-like object (see (b)) that moves on a plane by an appropriate moving mechanism (not shown) may be used as long as it can reciprocate in a direction substantially perpendicular to the intersection lines b and b '. A flexible web (see (c)) that is moved by the moving mechanism 18 including the transport rollers 15 may be used, and the shape and the material are not limited.

1 (b) and 1 (c), reference numeral 12 denotes a regulating member which is disposed between the linear evaporation source 11 and the support 13 and regulates the intersection angle θ of the steam flow 16 incident on the surface of the support 13. The regulating member 12 is provided to align the growth directions of the fine columnar crystals growing along the streamline direction of the vapor flow of the stimulable phosphor component in the vapor phase deposition method of the stimulable phosphor. That is, by limiting the direction of the stream of the vapor flow reaching the support surface, the growth direction of the fine columnar crystals can be aligned at a substantially constant angle with respect to the support surface. Therefore, by selecting the incident direction of the stream of the vapor flow reaching the support surface, the growth direction of the fine columnar crystals can be controlled, and the most convenient luminous excitation light irradiation and stimulable luminescence condensing can be performed. It is possible to form a depleted phosphor. The growth direction of the fine columnar crystal is preferably perpendicular to the surface of the support when stimulating excitation light is irradiated one-dimensionally and collected by a light-collecting member having a one-dimensional light-collecting surface.

Reference numeral 17 denotes control means for adjusting the amount of vapor adhering to the support 13 so as to be substantially constant irrespective of the position on the surface of the support. The control means 17 controls the control length d of the control member 12 as shown in FIG.
Of the evaporation source 11 can be appropriately controlled by the vapor amount distribution, or the evaporation amount of the evaporation source 11 can be appropriately controlled as shown in FIG.

That is, the layer thickness distribution of the phosphor layer deposited on the surface of the support 13 becomes uniform if the moving speed of the support 13 in the moving direction [Y direction in FIG. 1B] is constant. In the direction perpendicular to the moving direction (the length direction of the linear evaporation source [X direction in FIG. 1 (b)]), the amount of evaporation from the linear evaporation source 11 is constant regardless of the location, and If the regulation length d of 12 is constant at both the center and the periphery, the amount of vapor adhering to the support 13 has a large density at the center and a small density at the periphery. As a result, the thickness of the peripheral portion with respect to the center of the support surface is reduced by about 18%. The control means 17 makes the regulation length d of the regulation member 12 larger from the center to the periphery to correct the difference in the density of the amount of vapor, so that the crystal growth (deposition) rate on the support is equalized, It is possible to make the layer thickness distribution in the center and the peripheral part of the body surface almost uniform. Further, by controlling the amount of evaporation from the linear evaporation source 11 so that the peripheral region is larger than the central region, it is possible to make the layer thickness distribution at the center and the peripheral portion of the support surface uniform as described above. .

Therefore, the thickness of the phosphor layer on the support surface can be controlled in all directions by controlling the regulating length of the regulating member 12 and / or adjusting the amount of evaporation of the regulating member 12 by the control means 17 at the same time. A phosphor layer having a uniform thickness can be formed.

The term “uniform layer thickness” as used herein means that the distribution of the layer thickness over the entire deposition area is t ± 10, where t (μm) is the average of the maximum and minimum layer thicknesses of the phosphor layer on the support surface. % T (μ
m) or less, more preferably t ± 5% t (μm) or less. Needless to say, a desired layer thickness distribution can be provided as needed.

FIG. 2 shows that a large number of narrow strips 12a are arranged in a slidable manner so as to be displaceable in a restricting direction, and each of the narrow strips 12a is respectively connected to a plunger 12 of a hydraulic cylinder 12b.
The case where it is connected to b 'is shown. This hydraulic cylinder 12b
Is connected to the control means 17 via the digital valve 12c. Therefore, at the time of vapor deposition, the control means 17 receiving the information from the film thickness monitor 37 for monitoring the vapor deposition rate and the vapor deposition thickness drives the digital valve 12c, and controls the hydraulic pressure of each hydraulic cylinder 12b (the amount of protrusion of the plunger 12b '). By adjusting the position, each strip 12a is displaced in the regulating direction as shown in the drawing, so that the amount adhering to the support 13 is substantially constant irrespective of the position on the support surface.

3 (a) to 3 (e) show configuration diagrams when the type of vapor deposition method and the evaporation method are changed. The control means 17 controls the power distribution consumed by the resistance wire in the resistance heating evaporation method, or controls the power distribution and scanning speed of the electron beam in the electron beam heating evaporation method. However, control of the evaporation amount distribution by electron beam control is more effective when the phosphor is sublimable.

FIG. 3 (a) shows a single deposition in which the phosphor evaporated from the evaporation source 21 by the resistance heating method is deposited 23 on the support 22, and FIG. 2 shows a dual vapor deposition in which the phosphor evaporated by is deposited 23 on the support 22 through the regulating member 29. This dual vapor deposition is particularly effective in evaporating substances having different vapor pressures at the same time to obtain a vapor deposited film having a desired composition.

FIGS. 3 (c) and 3 (d) show electron beam heating vapor deposition, and FIG. 3 (c) shows that the vapor source 21 is linearly arranged with the electron gun 25 integrally with the vapor source 21 as shown in an enlarged view. The phosphor is evaporated by the scanning of the electron beam 24 and deposited on the support 22.
(D) shows a case in which the phosphor is evaporated by the scanning of the electron beam 24 emitted from the pierced electron gun 25 'and deposited on the support 22 using the piercing electron gun 25'.

FIG. 3 (e) shows a case where a high-frequency magnetron sputtering method is used. The evaporation source 21 used here is composed of a target 26 as shown in an enlarged view, and a target electrode 27 formed by combining a magnet 27a and an electrode plate (pole piece) 27b so as to form a magnetic field 28.

The linear evaporation source includes a case where a plurality of evaporation sources are linearly arranged as represented by FIG. 3 (c), in addition to a case where the crucible itself is linear. The evaporation source is not limited to a linear evaporation source, but may be a planar evaporation source (including a case where a linear evaporation source is provided).
However, the present invention can also be applied to a point evaporation source (a linear evaporation source having a dimension in the length direction of 0.4 to 2.0 times the width of the support, but not more than the lower limit). However, when the evaporation source is a planar evaporation source, as shown in FIG. 4, a support 22 is installed (fixed) opposite the evaporation source 21 so as to face the evaporation source 21.
When evaporating by the scanning of the electron beam 24 emitted from the electron gun 25, the scanning speed is controlled by the control means 17 so that the vapor amount becomes substantially constant irrespective of the position on the support body surface. 5, when the evaporation source is a point-like evaporation source 21, the support 22 is reciprocated in a horizontal direction above the evaporation source 21, and the evaporation source is placed between the evaporation source and the support. A regulating member 29 for regulating the crossing angle at which the steam flow from the surface enters the support surface is provided, and the regulating length d of the regulating member 29 is
The amount of vapor adhering to the support can be adjusted so as to be substantially constant regardless of the position on the surface of the support. In the case of this point evaporation source, there is no adjustment of the evaporation amount.

The present invention is particularly effective when producing a radiation image conversion panel comprising a stimulable phosphor layer requiring a large area.

The "radial image panel" mentioned here is a specific example of the intermediate recording medium, and has a high radiation absorption rate and a high light conversion rate (both are referred to as "radiation sensitivity"). It is required that the image has good graininess and high sharpness. Radiation sensitivity, granularity, and sharpness are closely related to the layer thickness of the stimulable phosphor layer as described above, and radiation sensitivity and granularity increase as the layer thickness increases, and sharpness decreases. , If the layer thickness is determined, the radiation sensitivity according to the layer thickness,
A radiation image conversion panel having granularity and sharpness is obtained. That is, the radiation image conversion panel has a large area and requires a uniform phosphor layer thickness, but if there is a large difference in the phosphor layer thickness to some extent, in addition to the variation in the radiation sensitivity, the obtained image can be obtained. Since it also affects graininess and sharpness, the diagnostic ability as a medical image is reduced.

Thus, according to the present invention, it is possible to eliminate the non-uniformity of the layer thickness and bring about a great effect on the improvement of the image characteristics.

Next, a vapor deposition apparatus and a vapor deposition method for forming a stimulable phosphor layer on a support surface by an electron beam vapor deposition method to which the present invention is applied will be described with reference to FIG.

FIG. 6 (a) is a schematic view of an example of the electron beam heating vapor deposition apparatus based on FIG. 3 (d), and FIG. 6 (b) is a plan view showing the positional relationship between the support and the evaporation source.

In this figure, 31 is a bell jar (vacuum tank), 32 is a pierced electron gun, 33 is an electron beam emitted from the pierced electron gun, and 35 is a crucible containing a stimulable phosphor (evaporation source) 34 to be evaporated. Reference numeral 311 denotes a support on which a stimulable phosphor is to be deposited, and reference numeral 313 denotes a support holder integrated with the support heater 312.

The crucible 35 has the same length as the width of the support 311 as shown in FIG. 6 (d), and is charged with the evaporation source 34 to form a linear evaporation source. The length a of the linear evaporation source 34 is preferably about 0.4 to 2.0 times the width b of the support 311 and more preferably 0.7 to 1.4 times. That is, if the ratio is 0.4 times or less, the film thickness distribution becomes too large to control, and if it is 2.0 or more, the vapor deposition efficiency deteriorates.

The electron beam 33 is incident on the linear evaporation source 34, performs a raster scan in the length direction, and performs evaporation along the length direction of the evaporation source. In this case, the power distribution or the scanning speed of the electron beam 33 can be controlled by the control means 17. That is, the amount of evaporation at the peripheral portion is controlled to be greater than that at the central portion of the evaporation source 34, so that the amount of vapor adhering to the support is uniform regardless of the position on the support surface.

As described above, the stimulable phosphor to be evaporated is uniformly dissolved or formed by pressing or hot pressing and charged into the crucible 35 as the linear evaporation source. At this time, it is preferable to perform a degassing treatment. Further, the evaporation source 34 does not necessarily need to be a stimulable phosphor, and may be a mixture of a stimulable phosphor material.

In addition, activator (act
ivator] may be doped later. For example, after depositing only RbBr as a base, Tl as an activator may be doped.

Further, the crucible 35 can be cooled by using a liquid cooling pipe 36 so that the temperature can be locally heated to evaporate a small amount of the evaporation source 34 having a uniform composition into a uniform composition.

The support 311 is placed facing the crucible 35 in which the evaporation source 34 is charged. The interval is suitably about 10 cm to 60 cm in accordance with the average range of the stimulable phosphor. Also, the support 31
1 may be heated to 50 ° C. to 350 ° C. by the heater 312. This support 311 is a motor (not shown)
It is moored by the transport wire 310 of the support holder 313 interlocked with the linear evaporator 34 and can move along the guide rail 39 in a direction perpendicular to the linear evaporation source 34. 38 is a member for regulating the steam flow.

314 is a main valve, 315 is an auxiliary valve, and 316 is a leak valve. The leak valve 316 is used for producing, maintaining, and adjusting a predetermined degree of vacuum in the bell jar 31 in conjunction with an exhaust device (not shown). The operation of the main valve 314 and the auxiliary valve 315 eliminates gas inside the bell jar 31 by operation, and brings about a vacuum degree of about 10 ^-4 Torr to 10 ^-6 Torr. At this time, an inert gas such as argon may be mixed.

Now, while moving the support at a constant speed to the left and right, the piercing electron gun 32 makes the electron beam 33 incident on the local portion of the evaporation source 34, evaporates a small amount, and monitors the deposition rate and the deposition thickness by the film thickness monitor 37. While proceeding the vapor deposition. Examples of the film thickness monitor 37 include a type that mechanically detects the effect of the momentum of the evaporative flying particles and a type that measures the intensity of the spectrum of the evaporative flying particles. To monitor and control the film thickness distribution on the support surface by the film thickness monitor online, many monitors are arranged along a linear evaporation source as shown in FIG. The detection signal of the monitor is output to the control means 17, and the regulating member
The regulation length of 38 is controlled as described in FIG. 2, or the amount of evaporation of the evaporation source 34 is controlled as described in FIG. Thereafter, the control means 17 stops the vapor deposition when it is detected by the film thickness monitor that uniform vapor deposition has been performed (that the phosphor layer has a predetermined thickness) regardless of the position on the support surface.

The monitoring of the film thickness monitor 37 and the control of the control means 17 can be performed online or offline.

A plurality of crucibles 35 charged with different evaporation sources 34
May be placed in a bell jar 31 and sequentially vapor-deposited to obtain a deposited layer composed of a plurality of types of stimulable phosphors.

Further, at the time of the vapor deposition, an object to be vapor-deposited (support or protective layer) may be cooled or heated as necessary, or after the vapor deposition, the stimulable phosphor layer may be subjected to a heat treatment.

Further, O ₂ , H ₂
The reactive vapor deposition may be performed by introducing a gas such as the above.

The layer thickness of the stimulable phosphor layer obtained by the vapor deposition method varies depending on the sensitivity to radiation of the intended radiation image conversion panel, the type of the stimulable phosphor, etc.
It is preferably selected from the range of 1000 μm. More preferably, it is selected from the range of 40 μm to 800 μm. That is, when the thickness of the stimulable phosphor layer is less than 30 μm, the radiation absorptivity is extremely reduced, so that the radiation sensitivity is deteriorated, and not only the image granularity is deteriorated, but also the stimulable phosphor layer is reduced. Is liable to be transparent, and the spread of stimulating excitation light in the stimulable phosphor layer in the lateral direction is remarkably increased, and the sharpness of the image tends to deteriorate, which is not preferable. If the thickness exceeds 1000 μm, sharpness is significantly reduced.

In the production of the radiation image conversion panel, the deposition rate of the stimulable phosphor layer varies depending on the intended characteristics and the like.
01 μm / min to 100 μm / min, preferably 0.1 μm / min to 10 μm / min, and 0.1 μm / min to 10 μm / min
More preferably, it is minutes. That is, the deposition rate is 0.01μ
When the rate is less than m / min, the productivity of the radiation image conversion panel is low, which is not preferable. On the contrary, when the deposition rate exceeds 100 μm / min, it is difficult to control the deposition rate, which is not preferable.

The "stimulable phosphor", after the first light or high-energy radiation is irradiated, optically, thermally, mechanically,
A phosphor that emits photostimulated light corresponding to the amount of initial light or high-energy radiation irradiated by a chemical or electrical stimulus (stimulated excitation).
It is a phosphor that shows stimulated emission by stimulated excitation light of 500 nm or more. The stimulable phosphor used in the radiation image conversion panel of the present invention is described, for example, in JP-A-48-80487. Phosphor represented by BaSO ₄ : Ax, JP-A-48
JP-A-48488 describes a phosphor represented by MgSO ₄ : Ax
SrSO is described in JP -80,489 _4: phosphor represented by Ax, Na ₂ SO ₄ as described in JP-A-51-29889, CaSO ₄
And BaSO ₄ or the like Mn, phosphors doped with at least one of Dy and Tb, which is described in JP-A-52-30487 BeO, L
iF, phosphors such as MgSO ₄ and CaF _2, Li ₂ B are described in JP-A-53-39277 ₄ O _7: Cu, phosphor Ag, JP 54-47883
Li ₂ O ・ (B ₂ O ₂ ) x: Cu and Li ₂ O ・ (B ₂ O ₂ )
x: phosphors such as Cu and Ag, SrS: Ce, Sm, SrS: Eu, Sm, La ₂ O ₂ S: Eu, Sm and (Zn, C) described in U.S. Pat.
d) Phosphor represented by S: Mn, x. Further, ZnS is described in JP-A-55-12142: Cu, Pb phosphor general formula BaO · xAl ₂ O _3: barium aluminate phosphor represented by Eu, and the general formula M ^II An alkaline earth metal silicate-based phosphor represented by O.xSiO ₂ : A is exemplified.

Further, an alkaline earth fluoride halide phosphor represented by the formula (Ba ₁ -x-yMg x Cay) FX: Eu ²⁺ described in JP-A-55-12143 is disclosed. A phosphor represented by the general formula LnOX: xA described in JP-A-12144;
The general formula described in No. 5-12145 is (Ba ₁ -xM ^II x) F
X: a phosphor represented by yA, a phosphor represented by the formula BaFX: xCe, yA described in JP-A-55-84389,
No. 5-160078 describes a rare earth element-activated divalent metal fluorohalide phosphor represented by the general formula M ^II FX · xA: yLn, and the general formula is ZnS: ACdS: A, (Zn, Cd) S : A, X and Cds: A, X
And a phosphor represented by any of the following general formulas xM ₃ (PO ₄ ) ₂ NX ₂ : yA M ₃ (PO ₄ ) ₂ : yA described in JP-A-59-38278. phosphor, following one of the general formulas described in _{JP-a-59-155487 nReX 3 · mAX '2:} xEu nReX 3 · mAX' 2: xEu, phosphor represented by YSM, JP 61 the following general formula are described in JP ^{-72087 M I X · aM II X} '2 · bM III X "3: alkali halide phosphor represented by cA, and JP 61-22
Is described in JP 8400 general formula M ^I X · bismuth-activated alkali halide phosphor, etc. represented by xBi the like it is.

In particular, an alkali halide phosphor is preferable because a stimulable phosphor layer can be easily formed by a method such as vapor deposition or sputtering.

However, the stimulable phosphor used in the radiation image conversion panel of the present invention is not limited to the above-described phosphor, and after irradiating radiation, shows stimulable luminescence when irradiated with stimulating excitation light. Any phosphor may be used as long as it is a phosphor.

Further, the radiation image conversion panel may be a stimulable phosphor layer group composed of one or more stimulable phosphor layers containing at least one kind of the stimulable phosphor described above. Also, the stimulable phosphor contained in each stimulable phosphor layer may be the same or different.

As the support used for the radiation image conversion panel, various polymer materials, glass, metals and the like are used, and a cellulose acetate film, a polyester film, a polyethylene terephthalate film, a polyamide film,
A plastic film such as a polyimide film, a triacetate film, or a polycarbonate film, a metal sheet such as an aluminum sheet, an iron sheet, or a copper sheet, or a metal sheet having a coating layer of the metal oxide is preferable.

The surface of the support may be a smooth surface or a mat surface for the purpose of improving the adhesion to the stimulable phosphor layer.

The surface of the support is uneven as shown in FIG. 7 (a).
41, or a structure in which isolated tile-like plates 43 are spread over the surface of the base 42 as shown in FIG. In the case of FIG. 7 (a), the stimulable phosphor layer is subdivided by the uneven surface 41 as shown in FIG. 7 (c), so that the sharpness of the image is further improved. In the case of FIG. 7 (b), the stimulable phosphor layer is deposited while maintaining the contour of the tile plate 43 of the support, and as a result, the stimulable phosphor layer is formed as shown in FIG. 7 (d). ), The sharpness of the image is further improved because it is composed of the columnar blocks 45 of the stimulable phosphor separated by the cracks 46.

Further, these supports may be provided with an undercoat layer on the surface on which the stimulable phosphor layer is provided for the purpose of improving the adhesion to the stimulable phosphor layer. The thickness of the support varies depending on the material used, but is generally 80 μm to 2000 μm, and more preferably 80 μm to 1000 μm from the viewpoint of handling.
m.

In the radiation image conversion panel, generally on the surface opposite to the surface on which the support of the stimulable phosphor layer is provided,
A protective layer for physically or chemically protecting the stimulable phosphor layer may be provided. This protective layer can be formed by directly applying the protective layer coating solution on the stimulable phosphor layer, or by bonding a separately formed protective layer on the stimulable phosphor layer. As the material of the protective layer, cellulose acetate, nitrocellulose, polymethyl methacrylate, polyvinyl butyral, polyvinyl formal,
Conventional protective layer materials such as polycarbonate, polyester, polyethylene terephthalate, polyethylene, vinylidene chloride, and nylon are used. Further, this protective layer is made of SiC, SiO ₂ , SiN, A
An inorganic material such as l ₂ O ₃ may be stacked. Generally, the thickness of these protective layers is preferably from 0.1 μm to 2000 μm.

〔Example〕

Next, examples of the present invention will be described in comparison with comparative examples.

* Comparative Example A crystallized glass of 389 mm × 445 mm × 1 mm was used as a support, and was set in an electron beam heating vapor deposition apparatus shown in FIG. 6A. RbBr, which is the base of the stimulable phosphor to be evaporated,
In a crucible 35, a linear evaporation source 34 is obtained. This linear evaporation source 34
Is a = 48 cm. Further, the regulation length of the regulation member 38 for regulating the steam flow is set to 9.5 cm (constant). At this time, the distance between crucible 35 and support 311 was 43 cm, and the distance between regulating member 38 and crucible 35 was 38. The support 311,
Details of the positional relationship between the crucible 35 and the regulating member 38 are as shown in FIGS. 6 (a) and 6 (b).

Next, the inside of the bell jar 31 was evacuated, kept at a vacuum of 2 × 10 ⁻⁶ Torr, and the support was heated and kept at 100 ° C.

Next, while the support is reciprocated at a speed of 50 cm / min, an electron beam 33 is scanned from the electron gun 32 on the surface of the evaporation source 34 in the direction a (the length direction of the evaporation source) (the linear velocity is constant and the amplitude is 48).
cm) and incident, and the stimulable phosphor was continuously evaporated to deposit at an evaporation area of 370 mm × 435 mm on the support surface at a deposition rate of 2 μm / min. At this time, the electron beam power and the a-direction beam speed were constant.

Then, while monitoring the deposition rate and the deposition thickness with the film thickness monitor, the deposition was advanced, and the deposition was terminated when the thickness of the stimulable phosphor layer reached 300 μm, and the radiation image conversion panel was obtained. Was.

In the radiation image conversion panel thus obtained, the layer thickness distribution with respect to the average layer thickness of the stimulable phosphor layer is ± 1% in the transport direction of the support (Y direction in FIG. 1 (b)). The layer thickness at both ends with respect to the center of the support surface in the direction a of the support was 60%, which was as thin as 40%. The layer thickness distribution was about ± 20%, and the phosphor layer forming efficiency was 4.3%. This is because the vapor flow density of the evaporation source is higher at the center than at the periphery. This is because the focus of the electron beam shifts at both ends of the electron beam scanning. This shift varies depending on the type of the deflection coil of the electron beam. In the case of the magnetic field type coil, the shift is smaller in the toroidal coil than in the quadrupole coil.

* Example- (1) The conditions were the same as those of the comparative example except that the scanning speed of the electron beam was corrected. The electron beam power was kept constant, and the scanning speed was corrected based on the layer thickness distribution obtained in the comparative example so that the amount of evaporation at both ends of the evaporation source was larger than that at the center of the evaporation source by the following equation.

V ′ _(a) = (D _(a) / _(a) ) ^L · V _(a) (V _(a) is the beam scanning velocity vector in the a direction, dash (′) is corrected, and D _(a) is V The phosphor layer thickness at the position on the support corresponding to _(a) , the bar is an average value, and L is a constant (=
3). The thickness distribution of the stimulable phosphor layer in the radiation image conversion panel obtained as described above with respect to the average thickness of the stimulable phosphor layer (± 1% in the transport direction of the support as in the comparative example) is a ± 4.5% in the direction, and was substantially uniform over the entire surface of the radiation image conversion panel. Further, the phosphor layer forming efficiency was 3.2%.

As a result, by using this radiation image conversion panel for diagnosis, it was possible to obtain a radiation image with excellent granularity and sharpness and high diagnostic ability.

* Example-(2) Except that the opposing edges of the regulating member are convex arc-shaped, the minimum interval at the center is 5.7 cm, and the maximum interval at both ends is 9.5 cm, so as to ease the passage of evaporative flow at both ends. The conditions are the same as in the comparative example.

In the radiation image conversion panel thus obtained, the layer thickness distribution with respect to the average layer thickness of the stimulable phosphor layer (± 1% in the transport direction of the support as in the comparative example) is the same as that of the support. The value was ± 4.5% in the direction a, and was substantially uniform over the entire surface of the radiation image conversion panel. The phosphor layer forming efficiency was 3.6%.

* Example-(3) The opposing edge of the regulating member is formed in a convex arc shape, the minimum interval at the center is 6.7 cm, and the maximum interval at both ends is 9.5 cm, so that the passage of evaporative flow at both ends is eased. Correction was performed using L = 1 in the correction formula shown in Example (1). Other conditions are the same as those of the comparative example.

In the radiation image conversion panel thus obtained, the layer thickness distribution with respect to the average layer thickness of the stimulable phosphor layer (± 1% in the transport direction of the support as in the comparative example) is the same as that of the support. The value was ± 4.4% in the direction a, and was substantially uniform over the entire surface of the radiation image conversion panel. The phosphor layer forming efficiency was 3.6%.

* Example-(4) A 48 cm x 48 cm planar evaporation source is used.

No regulating member, no support movement.

The scanning speed of the electron beam is obtained by making the embodiment (1) two-dimensional.

Other than the above, the conditions were the same as those of the comparative example.

In the radiation image conversion panel thus obtained, the layer thickness distribution with respect to the average layer thickness of the stimulable phosphor layer (± 1% in the transport direction of the support as in the comparative example) is the same as that of the support. ± 4.4% each in the direction a and the direction perpendicular thereto,
It was almost uniform over the entire surface of the radiation image conversion panel. The phosphor layer formation efficiency was 13.2%.

* Example- (5) Same conditions as in Example (1) except that a detection signal of a film thickness monitor arranged along a linear evaporation source was output to the control means, and the electron beam speed was controlled online.

In the radiation image conversion panel thus obtained, the layer thickness distribution with respect to the average layer thickness of the stimulable phosphor layer (± 1% in the transport direction of the support as in the comparative example) is the same as that of the support. The value was ± 2% in the direction a, and was substantially uniform over the entire surface of the radiation image conversion panel. Further, the phosphor layer forming efficiency was 3.2%.

〔The invention's effect〕

As described above, according to the present invention, the vapor flow from the evaporation source having a slit is incident on the surface of the support between the evaporation source, the support moving relatively to the evaporation source, and the evaporation source. Regulating member that regulates the angle of intersection, wherein the width of the slit in a direction perpendicular to the direction of conveyance of the support is equal to or greater than the width of the support in a direction perpendicular to the direction of conveyance of the support, and Since the width of the slit in the transport direction of the support is narrower at the center than at the end, the stimulable phosphor is finely columnar-crystallized by regulating the vapor flow, and the film is formed. By regulating the thickness,
It is possible to form a layer having a substantially constant layer thickness over a large area, and to reduce the variation in the layer thickness at the periphery of the support, thereby improving the film forming success rate and improving the productivity. It is effective.

[Brief description of the drawings]

1 (a) to 1 (c) are explanatory diagrams showing the configuration of a linear evaporation source, a support, and a regulating member, and FIG. 2 is a diagram of a regulating member configured so that the regulating length can be appropriately controlled by a steam amount distribution. FIGS. 3 (a) to 3 (e) are explanatory views showing aspects of the vapor deposition method, FIG. 4 is a schematic perspective view showing the configuration of a planar evaporation source and a support, and FIG. 6 (a) and 6 (b) are explanatory views of a phosphor vapor deposition apparatus, and FIGS. 7 (a) to 7 (d) are stimulative views showing the configuration of the evaporation source, the support, and the regulating member. FIG. 3 is an explanatory view showing an example of a support surface suitable for depositing a luminescent phosphor. 11,21,34… Linear evaporation source 12,29,38… Regulator 12a, 12b… Opposed edge 13,22,311… Supporter 14,23… Deposition area 15… Transport roller 16… … Vapor flow 17… control means 18… moving mechanism 24, 33… electron beam 25, 25 ', 32… electron gun 31… bell jar (vacuum tank) 35… crucible

Claims (1)

(57) [Claims] An intersecting angle at which a vapor flow from the evaporation source having a slit is incident on the surface of the support between the evaporation source and the support moving relatively to the evaporation source; Regulating member to regulate, the slit, the width of the support in the direction perpendicular to the transport direction of the support is not less than the width of the support in the direction perpendicular to the transport direction of the support, and the slit A phosphor vapor deposition apparatus, wherein the width of the support in the transport direction is smaller at the center than at the ends.