U.S. patent application number 11/636519 was filed with the patent office on 2007-05-03 for stimulable phosphor panel and method of producing stimulable phosphor panel.
This patent application is currently assigned to FUJI PHOTO FILM CO., LTD.. Invention is credited to Yuichi Hosoi, Seiji Tazaki.
Application Number | 20070096041 11/636519 |
Document ID | / |
Family ID | 35053283 |
Filed Date | 2007-05-03 |
United States Patent
Application |
20070096041 |
Kind Code |
A1 |
Tazaki; Seiji ; et
al. |
May 3, 2007 |
Stimulable phosphor panel and method of producing stimulable
phosphor panel
Abstract
The stimulable phosphor panel includes a support having a
substrate or the substrate and a sealing member, a stimulable
phosphor layer formed on the substrate being the support through
gas phase deposition, a moisture-proof protective layer for sealing
the stimulable phosphor layer and a sealing adhesive layer for
bonding an outer periphery of the moisture-proof protective layer
to the support. The sealing adhesive layer has a moisture
permeability of 1,000 g/m.sup.2day or less as an adhesive after
curing, a width of 2 mm to 10 mm, and a thickness of 0.5 .mu.m to
20 .mu.m. The producing method forms the stimulable phosphor layer
on the support through gas phase deposition, forms the adhesive
layer and bonds the moisture-proof protective layer to the support
through the adhesive layer. The stimulable phosphor panel is
capable of preventing deterioration of its characteristics due to
moisture absorption over a long period of time.
Inventors: |
Tazaki; Seiji; (Kanagawa,
JP) ; Hosoi; Yuichi; (Kanagawa, JP) |
Correspondence
Address: |
SUGHRUE MION, PLLC
2100 PENNSYLVANIA AVENUE, N.W.
SUITE 800
WASHINGTON
DC
20037
US
|
Assignee: |
FUJI PHOTO FILM CO., LTD.
Kanagawa
JP
|
Family ID: |
35053283 |
Appl. No.: |
11/636519 |
Filed: |
December 11, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11094213 |
Mar 31, 2005 |
7164140 |
|
|
11636519 |
Dec 11, 2006 |
|
|
|
Current U.S.
Class: |
250/484.4 |
Current CPC
Class: |
G01T 1/2012 20130101;
G21K 2004/08 20130101; G03B 42/08 20130101; G21K 4/00 20130101;
G21K 2004/10 20130101; C09K 11/7733 20130101 |
Class at
Publication: |
250/484.4 |
International
Class: |
G03B 42/08 20060101
G03B042/08 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 31, 2004 |
JP |
2004-105090 |
Claims
1. A stimulable phosphor panel comprising: a substrate which has a
groove formed so as to surround a predetermined region; a frame
which is inserted into said groove to be fixed to said substrate,
surrounds an inner side of said groove and protrudes from a surface
of said substrate; and a stimulable phosphor layer which is formed
by vacuum evaporation on the surface of said substrate surrounded
by said frame.
2. The stimulable phosphor panel according to claim 1, further
comprising a moisture-proof protective layer which covers said
frame and said stimulable phosphor layer.
3. The stimulable phosphor panel according to claim 2, wherein said
moisture-proof protective layer is bonded to an upper surface of
said frame.
4. The stimulable phosphor panel according to claim 1, wherein said
frame is fixed to the groove by an adhesive.
5. The stimulable phosphor panel according to claim 4, wherein a
heat resistant epoxy adhesive is used for said adhesive.
6. The stimulable phosphor panel according to claim 1, wherein a
difference in height between the upper surface of said frame and a
surface of said stimulable phosphor layer is 0.1 mm or less.
7. The stimulable phosphor panel according to claim 3, wherein said
moisture-proof protective layer and said stimulable phosphor layer
are bonded to each other.
8. The stimulable phosphor panel according to claim 2, wherein said
moisture-proof protective layer comprises a base, a first S102 film
formed on a surface of said base, a hybrid layer of Si02 and
polyvinyl alcohol formed on said first Sb2 film, and a second 5102
film formed on said hybrid layer.
9. The stimulable phosphor panel according to claim 1, wherein said
stimulable phosphor layer is formed of a stimulable phosphor
represented by CsBr:Eu.
10. A method of producing a stimulable phosphor panel which
includes a substrate, a stimulable phosphor layer formed on a
surface of said substrate by vacuum evaporation and a frame fixed
to said substrate so as to surround said stimulable phosphor layer,
comprising the steps of: fixing said frame to said substrate;
attaching a detachable tape to an upper surface of said frame to
restrict formation of said stimulable phosphor layer within said
frame; and forming said stimulable phosphor layer by said vacuum
evaporation.
11. The method of producing the stimulable phosphor panel according
to claim 10, further comprising the step of: forming a
moisture-proof protective layer whch covers said frame and said
s
12. The method of producing the stimulable phosphor panel according
to claim 11, wherein said moisture-proof protective layer is bonded
to an upper surface of said frame.
13. The method of producing the stimulable phosphor panel according
to claim 12, wherein said moisture-proof protective layer is bonded
to said stimulable phosphor layer.
14. The method of producing the stimulable phosphor panel according
to claim 10, wherein a difference in height between the upper
surface of said frame and a surface of said stimulable phosphor
layer is 0.1 mm or less.
15. The method of producing the stimulable phosphor panel according
to claim 10, said fixing step of said frame comprises the step of:
forming a groove in said substrate; and inserting said frame into
said groove to fix said frame to said substrate.
16. The method of producing the stimulable phosphor panel according
to claim 10, wherein said frame is fixed to said substrate by an
adhesive.
17. The method of producing the stimulable phosphor panel according
to claim 16, wherein a heat resistant epoxy adhesive is used for
said adhesive.
18. The method of producing the stimulable phosphor panel according
to claim 11, wherein said moisture-proof protective layer comprises
a base, a first S102 film formed on a surface of said base, a
hybrid layer of 5102 and polyvinyl alcohol formed on said first
Si02 film, and a second Si02 film formed on said hybrid layer.
19. The method of producing the stimulable phosphor panel according
to claim 10, wherein said stimulable phosphor layer is formed of a
stimulable phosphor represented by CsBr:Eu.
Description
[0001] This is a continuation of application Ser. No. 11/094,213
filed Mar. 31, 2005. The entire disclosure of the prior
application, application Ser. No. 11/094,213 is hereby incorporated
by reference.
[0002] This application claims priority on Japanese patent
application No. 2004-105090, the entire contents of which are
hereby incorporated by reference.
BACKGROUND OF THE INVENTION
[0003] The present invention relates to a field of stimulable
phosphor panel technology. In particular, the present invention
relates to a high quality stimulable phosphor panel having a
stimulable phosphor layer without deterioration of characteristics
due to moisture absorption, and to a method of producing the
stimulable phosphor panel.
[0004] There are known a class of phosphors which accumulate a
portion of applied radiations (e.g. x-rays, .alpha.-rays,
.beta.-rays, .gamma.-rays, electron beams, and uv (ultraviolet)
radiation) and which, upon stimulation by exciting light such as
visible light, give off a burst of light emission in proportion to
the accumulated energy. Such phosphors called stimulable phosphors
are employed in medical and various other applications.
[0005] An exemplary application is a radiation image information
recording and reproducing system which employs a stimulable
phosphor panel having a film formed of the stimulable phosphor
(stimulable phosphor layer). The film is hereinafter referred to
simply as a phosphor layer and the panel is hereinafter referred to
simply as a phosphor panel or sometimes as a radiation image
converting sheet. This radiation image information recording and
reproducing system has already been commercialized as FCR (Fuji
Computed Radiography) from Fuji Photo Film Co., Ltd.
[0006] In that system, a subject such as a human body is irradiated
with x-rays or the like to record radiation image information about
the subject on the phosphor panel (more specifically, the phosphor
layer). After the radiation image information is thus recorded, the
phosphor panel is scanned two-dimensionally with exciting light
such as laser light to produce stimulated emission which, in turn,
is read photoelectrically to yield an image signal. Then, an image
reproduced on the basis of the read image signal is output as the
radiation image of the subject, typically to a display device such
as CRT or on a recording material such as a photographic
material.
[0007] The phosphor panel is typically produced by the steps of
first preparing a coating solution having the particles of a
stimulable phosphor dispersed in a solvent containing a binder,
etc., applying the coating solution to a support in panel form that
is made of glass or resin, and drying the applied coating. Phosphor
panels are also known that are made by forming a phosphor layer on
a support through methods of gas phase deposition (vapor-phase film
formation) such as vacuum evaporation or sputtering, as disclosed
in JP 2789194 B and JP 5-249299 A. The phosphor layer prepared by
the gas phase deposition has excellent characteristics. First, it
contains less impurities since it is formed under vacuum; in
addition, it is substantially free of any substances other than the
stimulable phosphor, as exemplified by the binder, so it has high
uniformity in performance and still assures very high luminous
efficiency. One factor for deterioration of characteristics of the
phosphor panel is moisture absorption by the stimulable phosphor
layer.
[0008] The stimulable phosphor layer, in particular, an alkali
halide-based stimulable phosphor layer having favorable
characteristics, has high moisture absorption property and easily
absorbs moisture even in a normal environment (normal
temperature/normal humidity). As a result, deterioration of
sharpness of a reproduced image or the like occurs due to
deterioration of photostimulated luminescence characteristics, that
is, sensitivity, or deterioration of crystallinity of the
stimulable phosphor (destruction of columnar crystals in a case of
an alkali halide-based stimulable phosphor having a columnar
structure, for example).
[0009] In order to solve such problems, the phosphor layer is
sealed with a moisture-proof member in the phosphor panel.
[0010] For example, JP 2677822 B discloses a phosphor panel having
a phosphor layer sealed with a moisture-proof protective layer in
which deterioration of characteristics of the phosphor panel due to
moisture is prevented by: providing a sealing member on the
periphery of the phosphor layer; and filling a dry gas into a space
formed by a support, the protective layer, and the sealing
member.
[0011] Further, JP 2886165 B discloses a phosphor panel having a
stimulable phosphor layer similarly sealed with a protective layer,
including: a protective layer holding member provided to surround a
peripheral portion of the stimulable phosphor layer; and a low
refractive index layer, which has a lower refractive index than
that of the protective layer, provided between the stimulable
phosphor layer and the protective layer. The stimulable phosphor
layer is formed in a space blocked from the external atmosphere by
the protective layer, the protective layer holding member, and a
support.
[0012] The phosphor panels disclosed in JP 2677822 B and JP 2886165
B can prevent deterioration of characteristics due to moisture
absorption by the phosphor layer to some extent.
[0013] However, the inventors of the present invention have
conducted studies and have found that sufficient moisture-proof
property cannot be attained only by sealing of the phosphor layer
with a moisture-proof member, particularly under severe conditions
such as high humidity and high temperature. The moisture-proof
property is not yet sufficient for obtaining a phosphor panel
having excellent characteristics such as providing a reproduced
image with high sensitivity and favorable sharpness over a long
period of time.
SUMMARY OF THE INVENTION
[0014] The present invention aims at solving problems of prior art,
and an object of the present invention is therefore to provide a
high quality stimulable phosphor panel capable of preventing
deterioration of characteristics of a stimulable phosphor layer due
to moisture absorption over a long period of time.
[0015] Another object of the present invention is to provide a
method of producing the stimulable phosphor panel.
[0016] In order to achieve the above object, according to a first
aspect of the present invention, there is provided a stimulable
phosphor panel, including: a support; a stimulable phosphor layer
formed on said support through gas phase deposition; a
moisture-proof protective layer for sealing said stimulable
phosphor layer on said support; and a sealing adhesive layer for
bonding an outer periphery of said moisture-proof protective layer
to said support, wherein said sealing adhesive layer has a moisture
permeability of 1,000 g/m.sup.2day or less as an adhesive after
curing, a width of 2 mm to 10 mm, and a thickness of 0.5 .mu.m to
20 .mu.m.
[0017] In the provided a stimulable phosphor panel according to the
first aspect of the present invention, it is preferable that said
support comprises a substrate on which said stimulable phosphor
layer is formed and to which said moisture-proof protective layer
is bonded through said sealing adhesive layer. Futher, it is
preferable that a surface of said stimulable phosphor layer and
said moisture-proof protective layer are bonded together through a
stimulable phosphor adhesive layer. Futher, it is preferable that
said stimulable phosphor adhesive layer and said sealing adhesive
layer are unified. Futher, it is preferable that said support
comprises a substrate on which said stimulable phosphor layer is
formed and a sealing member which surrounds said stimulable
phosphor layer in a surface direction of said substrate and is
bonded to said moisture-proof protective layer through said sealing
adhesive layer. Futher, it is preferable that a difference between
heights of said sealing member and said stimulable phosphor layer
is 0.1 mm or less. Futher, it is preferable that a groove whose
shape corresponds to a bottom surface of said sealing member is
formed in a surface of said substrate and said sealing member is
inserted into said groove. Futher, it is preferable that said
moisture-proof protective layer comprises a base, a first SiO.sub.2
film formed on a surface of said base, a hybrid layer of SiO.sub.2
and polyvinyl alcohol formed on said first SiO.sub.2 film, and a
second SiO.sub.2 film formed on said hybrid layer. Futhermore, it
is preferable that said stimulable phosphor layer is formed of a
stimulable phosphor represented by CsBr:Eu.
[0018] Futher, according to second aspect of the present invention,
there is a method of producing a stimulable phosphor panel
including: forming a stimulable phosphor layer on a support through
gas phase deposition; forming an adhesive layer so as to have a
width in a range of 2 mm to 10 mm and a thickness in a range of 0.5
.mu.m to 20 .mu.m after sealing, by using an adhesive having a
moisture permeability of 1,000 g/m.sup.2day or less after curing;
and bonding a moisture-proof protective layer to said support
through said adhesive layer to seal said stimulable phosphor layer
formed on said support.
[0019] In a method of producing a stimulable phosphor panel
according to the second aspect of the present invention, it is
preferable that said support comprises a substrate, said stimulable
phosphor layer is formed on said substrate and said moisture-proof
protective layer is bonded to said substrate through said sealing
adhesive layer. Futher it is preferable that a surface of said
stimulable phosphor layer and said moisture-proof protective layer
are bonded together while said stimulable phosphor layer is sealed.
Futher it is preferable that said adhesive layer is formed on an
entire surface of said moisture-proof protective layer. Futher it
is preferable that said support comprises a substrate on which said
stimulable phosphor layer is formed and a sealing member which
surrounds in an outer periphery of said substrate a region where
said stimulable phosphor layer is formed and which is fixed on said
substrate prior to forming said stimulable phosphor layer, and said
sealing member and said moisture-proof protective layer are bonded
together through said adhesive layer to seal said stimulable
phosphor layer. Futher it is preferable that a difference between
heights of said sealing member and said stimulable phosphor layer
is 0.1 mm or less. Futher it is preferable that a groove whose
shape corresponds to a bottom surface of said sealing member is
formed in a surface of said substrate and said sealing member is
inserted into said groove. Futher it is preferable that said
stimulable phosphor layer is sealed with said adhesive layer
through heat lamination. Futher it is preferable that said adhesive
layer is heated in a range of a temperature lower than a softening
point of said adhesive layer by 30.degree. C. to 150.degree. C.
prior to said heat lamination. Futher it is preferable that said
moisture-proof protective layer comprises a base, a first SiO.sub.2
film formed on a surface of said base, a hybrid layer of SiO.sub.2
and polyvinyl alcohol formed on said first SiO.sub.2 film, and a
second SiO.sub.2 film formed on said hybrid layer. Futhermore it is
preferable that said stimulable phosphor layer is formed of a
stimulable phosphor represented by CsBr:Eu.
[0020] The present invention can provide a high quality stimulable
phosphor panel capable of preventing deterioration of
characteristics of a stimulable phosphor layer due to moisture
absorption over a long period of time even under severe conditions
such as high temperature and high humidity.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] In the accompanying drawings:
[0022] FIG. 1 is a sectional view showing a schematic structure of
an example of a phosphor panel according to the present
invention;
[0023] FIG. 2 is a sectional view showing a schematic structure of
another example of the phosphor panel according to the present
invention;
[0024] FIG. 3 is a sectional view showing a schematic structure of
still another example of the phosphor panel according to the
present invention;
[0025] FIG. 4 is a sectional view showing a schematic structure of
yet another example of the phosphor panel according to the present
invention;
[0026] FIG. 5 is a sectional view showing a schematic structure of
still yet another example of the phosphor panel according to the
present invention;
[0027] FIG. 6 is a sectional view showing a schematic structure of
an example of the phosphor panel according to the present
invention;
[0028] FIG. 7 is a sectional view showing a schematic structure of
another example of the phosphor panel according to the present
invention; and
[0029] FIG. 8 is a sectional view showing a schematic structure of
still another example of the phosphor panel according to the
present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0030] Hereinafter, a stimulable phosphor panel and a method of
producing the stimulable phosphor panel according to the present
invention will be described in detail using the attached
drawings.
[0031] FIG. 1 is a schematic sectional view showing an example of a
phosphor panel of the present invention produced through a
production method of the present invention.
[0032] A stimulable phosphor panel (hereinafter, referred to as
phosphor panel) 10 of the present invention is provided with: a
substrate 12; a film of a stimulable phosphor (stimulable phosphor
layer, hereinafter, referred to as phosphor layer) 14 formed
through gas phase deposition(or vacuum film deposition); a
moisture-proof protective layer 16 bonded to the substrate 12 by
sealing the phosphor layer 14; and a sealing adhesive layer 18 for
bonding the periphery of the moisture-proof protective layer 16 to
the substrate 12. In this example, a substrate 12 is used to
support the phosphor layer 14 as a support of the present
invention. In the present invention, the sealing adhesive layer 18
has a moisture permeability of 1,000 g/m.sup.2day or less, a width
a of 2 mm to 10 mm, and a thickness b of 0.5 .mu.m to 20 .mu.m.
[0033] According to the present invention, a structure (such as
layer structure) of the phosphor panel 10, methods of forming the
phosphor layer 14, the moisture-proof protective layer 16, and the
sealing adhesive layer 18, a heat treatment method for the phosphor
layer 14, a method of producing the phosphor panel 10, steps after
sealing of the phosphor layer 14, and steps before formation of the
phosphor layer 14 are not particularly limited as long as the above
conditions are satisfied. Basically, the phosphor panel 10 may be
produced through a method similar to a normal production
method.
[0034] The substrate 12 in the phosphor panel 10 of the present
invention is not particularly limited and various substrates used
in the phosphor panel 10 may be used.
[0035] Examples of the substrate 12 include: plastic films such as
a cellulose acetate film, polyester film, polyethylene
terephthalate film, polyamide film, polyimide film, triacetate
film, and polycarbonate film; glass plates made of quartz glass,
non-alkali glass, soda glass, heat resistant glass (Pyrex.TM.,
etc.), and the like; metal sheets such as an aluminum sheet, iron
sheet, copper sheet and chromium sheet; and metal sheets having a
metal oxide coating layer.
[0036] The phosphor layer 14 is formed on a surface of the
above-mentioned substrate 12 through gas phase deposition.
[0037] In the present invention, various treatments can be carried
out before formation of the phosphor layer 14 as described above.
For example, a reflective film may be formed on a surface of the
substrate 12 for reflecting photostimulated luminescence, or a
barrier layer or the like may additionally be formed on the
reflective film for protecting the reflective film. That is, in the
present invention, the phosphor layer 14 may be formed on a surface
of the substrate 12 having the reflective film or the protective
film formed thereon.
[0038] Various materials can be used as the stimulable phosphor
constituting the phosphor layer 14. Preferred examples of the
stimulable phosphor are given below.
[0039] Stimulable phosphors disclosed in U.S. Pat. No. 3,859,527
are "SrS:Ce, Sm", "SrS:Eu, Sm", "ThO2:Er", and "La2O2S:Eu, Sm".
[0040] JP 55-12142 A discloses "ZnS:Cu, Pb", "BaO.xAl2O3:Eu
(0.8.ltoreq.x.ltoreq.10)", and stimulable phosphors represented by
the general formula "M.sup.IIO.xSiO.sub.2:A". In this formula,
M.sup.II is at least one element selected from the group consisting
of Mg, Ca, Sr, Zn, Cd, and Ba, A is at least one element selected
from the group consisting of Ce, Tb, Eu, Tm, Pb, Tl, Bi, and Mn,
and 0.5.ltoreq.x.ltoreq.2.5.
[0041] Stimulable phosphors represented by the general formula
"LnOX:xA" are disclosed by JP 55-12144 A. In this formula, Ln is at
least one element selected from the group consisting of La, Y, Gd,
and Lu, X is at least one element selected from Cl and Br, A is at
least one element selected from Ce and Tb, and
0.ltoreq.x.ltoreq.0.1.
[0042] Stimulable phosphors represented by the general formula
"(Ba.sub.1-x, M.sup.2+.sub.x)FX:yA" are disclosed by JP 55-12145 A.
In this formula, M.sup.2+ is at least one element selected from the
group consisting of Mg, Ca, Sr, Zn, and Cd, X is at least one
element selected from Cl, Br, and I, A is at least one element
selected from Eu, Tb, Ce, Tm, Dy, Pr, Ho, Nd, Yb, and Er,
0.ltoreq.x.ltoreq.0.6, and 0.ltoreq.y.ltoreq.0.2.
[0043] JP 57-14825 A discloses the following stimulable phosphors.
That is, the stimulable phosphors are represented by the general
formula "xM.sub.3(PO.sub.4).sub.2.NX.sub.2:yA" or
"M.sub.3(PO.sub.4).sub.2.yA". In this formula, M and N are each at
least one element selected from the group consisting of Mg, Ca, Sr,
Ba, Zn, and Cd, X is at least one element selected from F, Cl, Br,
and I, A is at least one element selected from Eu, Tb, Ce, Tm, Dy,
Pr, Ho, Nd, Yb, Er, Sb, Tl, Mn, and Sn, 0.ltoreq.x.ltoreq.6, and
0.ltoreq.y.ltoreq.1.
[0044] Stimulable phosphors are represented by the general formula
"nReX.sub.3.mAX'.sub.2:xEu" or "nReX.sub.3.mAX'.sub.2:xEu, ySm". In
this formula, Re is at least one element selected from the group
consisting of La, Gd, Y, and Lu, A is at least one element selected
from Ba, Sr, and Ca, X and X' are each at least one element
selected from F, Cl, and Br,
1.times.10.sup.-4<x<3.times.10.sup.-1,
1.times.10.sup.-4<y<1.times.10.sup.-1, and
1.times.10.sup.-3<n/m<7.times.10.sup.-1.
[0045] Alkali halide-based stimulable phosphors are represented by
the general formula
"M.sup.IX.aM.sup.IIX'.sub.2.bM.sup.IIIX''.sub.3:cA". In this
formula, M.sup.I represents at least one element selected from the
group consisting of Li, Na, K, Rb, and Cs. M.sup.II represents at
least one divalent metal selected from the group consisting of Be,
Mg, Ca, Sr, Ba, Zn, Cd, Cu, and Ni. M.sup.III represents at least
one trivalent metal selected from the group consisting of Sc, Y,
La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Al, Ga,
and In. X, X', and X'' each represent at least one element selected
from the group consisting of F, Cl, Br, and I. A represents at
least one element selected from the group consisting of Eu, Tb, Ce,
Tm, Dy, Pr, Ho, Nd, Yb, Er, Gd, Lu, Sm, Y, Tl, Na, Ag, Cu, Bi, and
Mg, 0.ltoreq.a<0.5, 0.ltoreq.b<0.5, and
0.ltoreq.c<0.2.
[0046] Stimulable phosphors represented by the general formula
"(Ba1.sub.-x, M.sup.II.sub.x)F.sub.2.aBaX.sub.2:yEu, zA" are
disclosed by JP 56-116777 A. In this formula, M.sup.II is at least
one element selected from the group consisting of Be, Mg, Ca, Sr,
Zn, and Cd, X is at least one element selected from Ci, Br, and I,
A is at least one element selected from Zr and Sc,
0.5.ltoreq.a.ltoreq.1.25, 0.ltoreq.x.ltoreq.1,
1.times.10.sup.-6.ltoreq.y.ltoreq.2.times.10.sup.-1 and
0.ltoreq.z.ltoreq.1.times.10.sup.-2.
[0047] Stimulable phosphors represented by the general formula
"M.sup.IIIOX:xCe" are disclosed by JP 58-69281 A. In this formula,
M.sup.III is at least one trivalent metal selected from the group
consisting of Pr, Nd, Pm, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb, and Bi, X
is at least one element selected from Cl and Br, and
0.ltoreq.x.ltoreq.0.1.
[0048] Stimulable phosphors represented by the general formula
"Ba.sub.1-xM.sub.aL.sub.aFX:yEu.sup.2+" are disclosed by JP
58-206678 A. In this formula, M is at least one element selected
from the group consisting of Li, Na, K, Rb, and Cs, L is at least
one trivalent metal selected from the group consisting of Sc, Y,
La, Ce, Pr, Nd, Pm, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Al, Ga, In,
and Tl, X is at least one element selected from Cl, Br, and I,
1.times.10.sup.-2.ltoreq.x.ltoreq.0.5, 0.ltoreq.y.ltoreq.0.1, and a
is x/2.
[0049] Stimulable phosphors represented by the general formula
"M.sup.IIFX.aM.sup.IX'.bM'.sup.IIX''.sub.2'cM.sup.IIIX.sub.3.xA:yEu.sup.2-
+" are disclosed by JP 59-75200 A. In this formula, M.sup.II is at
least one element selected from the group consisting of Ba, Sr, and
Ca, M.sup.I is at least one element selected from Li, Na, K, Rb,
and Cs, M'.sup.II is at least one divalent metal selected from Be
and Mg, M.sup.III is at least one trivalent metal selected from the
group consisting of Al, Ga, In, and Tl, A is a metal oxide, X, X',
and X' are each one element selected from the group consisting of
F, Cl, Br, and I, 0.ltoreq.a.ltoreq.2,
0.ltoreq.b.ltoreq.1.times.10.sup.-2,
0.ltoreq.c.ltoreq.1.times.10.sup.-2, and a+b+c.ltoreq.10.sup.-6,
0<x.ltoreq.0.5, and 0<y.ltoreq.0.2.
[0050] Alkali halide-based stimulable phosphors disclosed by
JP-57-148285 A are preferred because they have excellent
photostimulated luminescence characteristics and the effect of the
present invention is advantageously obtained. Alkali halide-based
stimulable phosphors in which MI contains at least Cs, X contains
at least Br, and A is Eu or Bi are more preferred, and stimulable
phosphors represented by the general formula "CsBr:Eu" are
particularly preferred.
[0051] The phosphor layer 14 is formed of such a stimulable
phosphor as described above. A method of forming the phosphor layer
14 is not particularly limited and various gas phase deposition
techniques such as vacuum evaporation, sputtering, chemical vapor
deposition (CVD) can be employed.
[0052] Of those, vacuum evaporation is preferably employed to form
the phosphor layer 14 from the viewpoint of productivity or the
like. In particular, multi-source evaporation is further preferably
employed to form the phosphor layer 14, in which a material for a
phosphor component and a material for an activator component are
evaporated separately under heating. For example, the phosphor
layer 14 of "CsBr:Eu" is preferably formed through multi-source
evaporation in which cesium bromide (CsBr) as a material for the
phosphor component and europium bromide (EuBr.sub.x (x is generally
2 to 3)) as a material for the activator component are evaporated
separately under heating.
[0053] A heating method in vacuum evaporation is not particularly
limited. The phosphor layer 14 may be formed through electron beam
heating employing an electron gun or the like or through resistance
heating. When the phosphor layer 14 is formed through multi-source
evaporation, all materials may be evaporated under heating by the
same heating means (such as electron beam heating). Alternatively,
the material for the phosphor component may be evaporated under
heating through electron beam heating, and the material for the
activator component, which is in a trace amount, may be evaporated
under heating through resistance heating.
[0054] There are no particularly limited conditions for film
deposition under which the phosphor layer 14 must be formed, and
the phosphor layer 14 may be formed under conditions for film
deposition arbitrarily determined in accordance with a film
deposition method or a composition or the like of the phosphor
layer 14 to be formed. For example, the phosphor layer 14 is
preferably formed through vacuum evaporation at a degree of vacuum
of 1.times.10-.sup.5 Pa to 1.times.10.sup.-2 Pa and a film
deposition rate of 0.05 .mu.m/min to 300 .mu.m/min. Note that in
forming the phosphor layer 14 through multi-source evaporation,
evaporation rates of the materials for the phosphor component and
the activator component are controlled such that an amount ratio of
the phosphor component to the activator component falls within a
target range.
[0055] According to the studies conducted by the inventors of the
present invention, when various stimulable phosphors as described
above, in particular, an alkali halide-based stimulable phosphor
such as CsBr:Eu is subjected to film deposition through vacuum
evaporation, the phosphor layer 14 is preferably formed by:
evacuating a system to a high degree of vacuum once; introducing an
argon gas, a nitrogen gas, or the like into the system to adjust to
a medium degree of vacuum of about 0.01 Pa to 3 Pa; and carrying
out vacuum evaporation through resistance heating under medium
vacuum. The alkali halide-based phosphor layer such as CsBr:Eu has
a columnar crystal structure, and the phosphor layer 14 obtained
through film deposition under medium vacuum has a particularly
favorable columnar crystal structure, and thus is preferable from
the viewpoint of sharpness of an image with photostimulated
luminescence characteristics.
[0056] The phosphor layer 14 formed may be heated at 300.degree. C.
or lower during film deposition through heating of the substrate 12
or the like. The heating of the phosphor layer 14 is preferably
carried out at 200.degree. C. or lower.
[0057] The thickness of the phosphor layer 14 is not particularly
limited, but the phosphor layer 14 preferably has a thickness of 50
.mu.m or more. The phosphor layer 14 particularly preferably has a
thickness of 200 .mu.m or more.
[0058] The thus-formed phosphor layer 14 is subjected to heat
treatment (annealing) for favorably developing photostimulated
luminescence characteristics and improving the photostimulated
luminescence characteristics thereof.
[0059] The annealing condition for the phosphor layer 14 is not
particularly limited. For example, the phosphor layer 14 is
preferably annealed in an inert atmosphere such as a nitrogen
atmosphere at 50.degree. C. to 600.degree. C. (particularly
100.degree. C. to 300.degree. C.) for 10 minutes to 10 hours
(particularly 30 minutes to 3 hours).
[0060] The heat treatment for the phosphor layer 14 may be carried
out through a known method such as a method employing a firing
furnace. Further, if a vacuum evaporation apparatus includes a
heating means for the substrate 12, the heat treatment can be
carried out using the heating means.
[0061] In the phosphor panel 10 of the present invention, the
moisture-proof protective layer 16 covers and seals the phosphor
layer 14 for preventing moisture absorption of the phosphor layer
14 formed through vacuum evaporation (gas phase deposition).
[0062] The moisture-proof protective layer 16 is not particularly
limited as long as it has sufficient moisture-proof property, and
various types thereof can be used.
[0063] For example, the moisture-proof protective layer 16 is
formed of 3 layers on a polyethylene terephthalate (PET) film: an
SiO.sub.2 film; a hybrid layer of SiO.sub.2 and polyvinyl alcohol
(PVA); and an SiO.sub.2 film. Other preferable examples of the
moisture-proof protective layer 16 include: a glass sheet (film); a
resin film of polyethylene terephthalate, polycarbonate, or the
like; and a film having an inorganic substance such as SiO.sub.2,
Al.sub.2O.sub.3, or SiC deposited on the resin film. For formation
of the moisture-proof protective film 16 having 3 layers of
SiO.sub.2 film/hybrid layer of SiO.sub.2 and PVA/SiO.sub.2 film on
the PET film, the SiO.sub.2 films may be formed through sputtering
and the hybrid layer may be formed through a sol-gel process, for
example. The hybrid layer is preferably formed to have a ratio of
PVA to SiO.sub.2 of 1:1.
[0064] In the phosphor panel 10 of the present invention, the
sealing adhesive layer 18 is used to bond together the
moisture-proof protective layer 16 and the substrate 12 to seal the
phosphor layer 14 with the moisture-proof protective layer 16. In
the present invention, the sealing adhesive layer 18 is formed
using an adhesive having a moisture permeability of 1,000
g/m.sup.2day or less (under conditions of 40.degree. C. and a
relative humidity of 90%, per 100 .mu.m of thickness) and has a
width a of 2 mm to 10 mm and a thickness b of 0.5 .mu.m to 20
.mu.m.
[0065] The moisture-proof protective layer 16, the phosphor layer
14 and the substrate 12 are bonded together through the sealing
adhesive layer 18, and thus the phosphor panel 10 of the present
invention develops exceptional moisture-proof property and can
maintain favorable characteristics over a long period of time even
under severe conditions such as high temperature and high
humidity.
[0066] The stimulable phosphor forming the stimulable phosphor
layer 14, in particular, an alkali halide-based stimulable phosphor
has moisture absorption property and easily absorbs moisture even
under normal conditions, resulting in deterioration of sensitivity
or sharpness in a reproduced image, or the like. In order to
prevent such disadvantages, the phosphor layer 14 has been
conventionally sealed with the moisture-proof protective layer 16,
but a sufficient moisture-proof effect is not obtained through the
current sealing method for the phosphor layer 14 as described
above. The inventors of the present invention have conducted
intensive studies for solving such problems, and have found that
moisture permeation from a sealing portion during sealing of the
phosphor layer 14 deteriorates the characteristics of the phosphor
panel. Further, the inventors of the present invention have found
that moisture permeation from the sealing adhesive layer 18 between
the substrate 12 and the moisture-proof protective layer 16 can be
prevented by providing the sealing adhesive layer 18 with the above
structure, and have completed the present invention.
[0067] A material for forming the sealing adhesive layer 18 is not
particularly limited, and various adhesives can be used as long as
the sealing adhesive layer 18 can realize a moisture permeability
of 1,000 g/m.sup.2day or less after curing with a width a in a
range of 2 mm to 10 mm and a thickness b in a range of 0.5 .mu.m to
20 .mu.m.
[0068] For example, an adhesive of an epoxy resin, a
polyester-based resin, or the like is preferable, and a
thermoplastic polymer resin is particularly preferable as the
material. An adhesive having a moisture permeability of 500
g/m.sup.2day or less per 100 .mu.m thickness after curing under the
conditions of 40.degree. C. and a relative humidity of 90% is
preferably used. An adhesive having a moisture permeability
exceeding 1,000 g/m.sup.2day provides a small moisture permeation
preventing effect and sufficient moisture-proof effect cannot be
obtained.
[0069] As described above, the sealing adhesive layer 18 has a
width a of 2 mm to 10 mm, and a thickness b of 0.5 .mu.m to 20
.mu.m.
[0070] The sealing adhesive layer 18 having a width a of less than
2 mm may not provide sufficient adhesion between the substrate 12
and the moisture-proof protective layer 16, causing problems such
as peeling of the moisture-proof protective layer 16. In contrast,
the sealing adhesive layer 18 having a width a exceeding 10 mm may
excessively increase the size of the sealing adhesive layer 18 with
respect to the size of the entire phosphor panel 10 and decreases
the size of an image pickup surface with respect to that of the
phosphor panel 10, causing problems in practicality of the phosphor
panel 10. The sealing adhesive layer 18 preferably has a width a of
3 mm to 6 mm.
[0071] The sealing adhesive layer 18 having a thickness b of less
than 0.5 .mu.m may not provide sufficient adhesion between the
substrate 12 and the moisture-proof protective layer 16, causing
problems such as peeling of the moisture-proof protective layer 16.
In contrast, the sealing adhesive layer 18 having a thickness b
exceeding 20 .mu.m may easily cause moisture permeation from the
sealing adhesive layer 18. The sealing adhesive layer 18 preferably
has a thickness of 0.8 .mu.m to 10 .mu.m.
[0072] Hereinafter, an example of a method of producing the
phosphor panel 10 of the present invention will be described.
[0073] First, the phosphor layer 14 is formed on the surface of the
substrate 12 as described above. Next, an arbitrarily selected
adhesive is applied using a dispenser or the like at a bonding
position between the substrate 12 and the moisture-proof protective
layer 16 surrounding the phosphor layer 14 on the surface of the
substrate 12 such that the sealing adhesive layer 18 has a width a
of 2 mm to 10 mm and a thickness b of 0.5 .mu.m to 20 .mu.m. Then,
the phosphor layer 14 is covered with the moisture-proof protective
layer 16.
[0074] Finally, a press mold having a pressing surface constituted
of rubber and corresponding to the shape of a sealing portion
(region with adhesive applied) of the moisture-proof protective
layer 16 with the sealing adhesive layer 18 is used to press the
sealing portion against the substrate 12. This state is maintained
to cure the adhesive. Thus, the moisture-proof protective layer 16
and the substrate 12 are bonded together through the sealing
adhesive layer 18 and the phosphor layer 14 is sealed to thereby
obtain the phosphor panel 10.
[0075] As described above, a reflective film, a barrier film, and
the like may be formed on the substrate 12 before formation of the
phosphor layer 14, and the substrate having the films formed
thereon may be used as the substrate 12. As described above, there
is no particular limitation after sealing of the phosphor layer
14.
[0076] FIG. 2 shows another example of the phosphor panel according
to the present invention.
[0077] A phosphor panel 20 basically has the same structure as the
example shown in FIG. 1, and thus the same reference numerals
represent the same members. Different members are mainly described
below.
[0078] The phosphor panel 20 shown in FIG. 2 further includes a
stimulable phosphor adhesive layer 22 for bonding together the
phosphor layer 14 and the moisture-proof protective layer 16, in
addition to the phosphor panel 10 of FIG. 1. The phosphor panel 20
preferably has the stimulable phosphor adhesive layer 22 from the
viewpoints of preventing floating of the moisture-proof protective
layer 16, durability over a long period of time, and the like.
[0079] The stimulable phosphor adhesive layer 22 is not
particularly limited as long as it provides sufficient adhesion and
has optical characteristics that do not inhibit incidence of
radiation or excitation light and emission of photostimulated
luminescence. The stimulable phosphor adhesive layer 22 may be
formed using various adhesives. The adhesive is preferably an epoxy
rein or a polyester-based resin, particularly preferably a
thermoplastic polymer resin such as a polyester-based resin, for
example. The use of the thermoplastic polymer resin allows bonding
through heat lamination, thereby improving workability and
productivity. The thickness of the stimulable phosphor adhesive
layer 22 is not particularly limited, but is preferably 0.8 .mu.m
to 10 .mu.m.
[0080] The size of the stimulable phosphor adhesive layer 22 is not
particularly limited as long as it is formed into a size that
covers the surface of the phosphor layer 14. A method and
conditions for forming the stimulable phosphor adhesive layer 22
are not particularly limited. For example, the stimulable phosphor
adhesive layer 22 is preferably formed through application.
[0081] Hereinafter, an example of the method of producing the
phosphor panel 20 will be described.
[0082] First, as in the phosphor panel 10 of FIG. 1, the phosphor
layer 14 is formed on the surface of the substrate 12, and the
sealing adhesive layer 18 is formed at a bonding position between
the substrate 12 and the moisture-proof protective layer 16
surrounding the phosphor layer 14 on the surface of the substrate
12 in the same manner as the method of producing the phosphor panel
10.
[0083] Meanwhile, the stimulable phosphor adhesive layer 22 is
formed to have a predetermined thickness through application using
an arbitrarily selected adhesive in a predetermined region at the
center of the surface of the moisture-proof protective layer 16
and/or on the surface of the phosphor layer 14.
[0084] Finally, the phosphor layer 14 is covered with the
moisture-proof protective layer 16 having the stimulable phosphor
adhesive layer 22. Heat lamination is carried out at a
predetermined temperature and linear velocity using a laminating
machine for contact bonding under pressure, and the moisture-proof
protective layer 16 and the phosphor layer 14 are bonded together
through the stimulable phosphor adhesive layer 22, for example. The
moisture-proof protective layer 16 that has the stimulable phosphor
adhesive layer 22 and covers the phosphor layer 14 is preferably
passed through the laminating machine in one direction a
predetermined number of times (several times) for improving the
bonding strength. Next, these layers are pressed using a press mold
in the same manner as the phosphor panel 10. The moisture-proof
protective layer 16 and the substrate 12 are bonded together
through the sealing adhesive layer 18 to thereby seal the phosphor
layer 14.
[0085] The sealing portion and the phosphor layer 14 are heated
within a range of a temperature lower than a softening point of the
sealing adhesive layer 18 by 30.degree. C. to 150.degree. C. before
sealing of the phosphor layer 14 with the moisture-proof protective
layer 16. Thus, the bonding strength can be improved in bonding of
the moisture-proof protective layer 16 to the substrate 12 through
the sealing adhesive layer 18, and a favorable bonding strength can
be obtained in one lamination process. The heating may be carried
out through heating of the substrate 12, for example.
[0086] FIG. 3 shows still another example of the phosphor panel
according to the present invention.
[0087] A phosphor panel 26 basically has the same structure as the
example shown in FIG. 1, and thus the same reference numerals
represent the same members. Different members are mainly described
below.
[0088] The phosphor panel 26 shown in FIG. 3 is the phosphor panel
20 of FIG. 2 having the stimulable phosphor adhesive layer 22 and
the sealing adhesive layer 18 formed integrally. To be specific, as
shown in FIG. 3, the phosphor panel 26 includes a stimulable
phosphor adhesive layer 28 serving as the sealing adhesive layer 18
and the stimulable phosphor adhesive layer 22 bonding together the
moisture-proof protective layer 16 and the phosphor layer 14. The
phosphor panel 26 preferably has the stimulable phosphor adhesive
layer 28 from the viewpoint of durability or the like, as in the
stimulable phosphor adhesive layer 22. Further, with such a
structure, the moisture-proof protective layer 16, the phosphor
layer 14, and the substrate 12 can be bonded together
simultaneously, which is advantageous from the viewpoints of
productivity and workability. The stimulable phosphor adhesive
layer 28 preferably has a thickness of 0.8 .mu.m to 10 .mu.m.
[0089] The stimulable phosphor adhesive layer 28 may be formed from
the same material as that of the sealing adhesive layer 18 of the
phosphor panel 10 as long as it has optical characteristics that do
not inhibit incidence of radiation or excitation light and emission
of photostimulated luminescence. The use of a thermoplastic polymer
resin allows bonding through heat lamination, thereby improving
workability and productivity.
[0090] A method and conditions for forming the stimulable phosphor
adhesive layer 28 are not particularly limited. The stimulable
phosphor adhesive layer 28 is formed to have a predetermined
thickness over the entire surface of the moisture-proof protective
layer 16 such that the sealing portion (corresponding to the
sealing adhesive layer 18) between the substrate 12 and the
moisture-proof protective layer 16 after sealing has a width of 2
mm to 10 mm and a thickness of 0.5 .mu.m to 20 .mu.m. For example,
the stimulable phosphor adhesive layer 28 is preferably formed
through application.
[0091] An example of a method of producing the phosphor panel 26
will be described.
[0092] The phosphor panel 14 is formed on the surface of the
substrate 12 as described above.
[0093] Meanwhile, the stimulable phosphor adhesive layer 28 is
formed to have a predetermined thickness using an arbitrarily
selected adhesive on the entire surface of the moisture-proof
protective layer 16. The stimulable phosphor adhesive layer 28 is
formed such that the sealing portion between the substrate 12 and
the moisture-proof protective layer 16 after sealing has a width a
of 2 mm to 10 mm and a thickness b of 0.5 .mu.m to 20 .mu.m.
[0094] The stimulable phosphor adhesive layer 28 bonds together the
moisture-proof protective layer 16 and the phosphor layer 14, and
further bonds together the moisture-proof protective layer 16 and
the substrate 12. The stimulable phosphor adhesive layer 28
integrates a layer for bonding together the moisture-proof
protective layer 16 and the phosphor layer 14 with a layer for
bonding together the phosphor layer 14 with the substrate 12, and
can be formed through one application process. The stimulable
phosphor adhesive layer 28 is preferable from the viewpoint of
durability or the like as described above.
[0095] The phosphor layer 14 is covered with the moisture-proof
protective layer 16 having the stimulable phosphor adhesive layer
28. Heat lamination is carried out at a predetermined temperature
and linear velocity for bonding together the phosphor layer 14 and
the moisture-proof protective layer 16, and the moisture-proof
protective layer 16 and the substrate 12, as in the phosphor panel
20 of FIG. 2. The surface of the phosphor layer 14 is not flush
with a top surface of the substrate 12, and thus a peripheral
sealing portion parallel with a direction of the lamination may not
be favorably bonded. Thus, when the surface of the phosphor layer
14 is not flush with the top surface of the substrate 12, the
direction of the lamination is preferably rotated by 90.degree. and
lamination is carried out a predetermined number of times in each
direction, to thereby seal the phosphor layer 14.
[0096] The substrate 12 may be heated before sealing of the
phosphor layer 14 with the moisture-proof protective layer 16 as in
the previous examples.
[0097] FIG. 4 shows yet another example of the phosphor panel
according to the present invention.
[0098] A phosphor panel 32 basically has the same structure as the
example shown in FIG. 1, and thus the same reference numerals
represent the same members. Different members are mainly described
below.
[0099] The phosphor panel 32 shown in FIG. 4 further includes a
frame 24 (sealing member) on the substrate 12, in addition to the
phosphor panel 10 of FIG. 1. That is, in this example, the
substrate 12 and the frame 24 are used as the support of the
invention for supporting the phosphor layer 14. The moisture-proof
protective layer 16 is bonded to the frame 24, to thereby seal the
phosphor layer 14. Thus, the phosphor panel 32 includes the
stimulable phosphor adhesive layer 28 for bonding together the
moisture-proof protective layer 16 and the frame 24, and the
moisture-proof protective layer 16 and the phosphor layer 14.
[0100] A difference between heights of the top surface of the frame
24 and the surface of the phosphor layer 14 is preferably small. A
small difference prevents steep bending of the moisture-proof
protective layer 16 at a boundary between the sealing portion and
the phosphor layer 14 during heat lamination, and can prevent
deterioration of the moisture-proof property due to destruction of
the moisture-proof layer (SiO.sub.2 layer) by the bending. Thus,
the difference between heights of the top surface of the frame 24
and the surface of the phosphor layer 14 is preferably as small as
possible when the frame 24 is fixed on the substrate 12, and the
difference is particularly preferably 0.1 mm or less. The width of
the frame 24 is not particularly limited but is preferably 2 mm to
10 mm because the width of the frame 24 often corresponds to the
width of the sealing adhesive layer 18.
[0101] A material for forming the frame 24 is not particularly
limited. Aluminum is preferably used, for example.
[0102] The stimulable phosphor adhesive layer 28 may be formed in
the same manner as that of the phosphor panel 26 of FIG. 3 using
the same material therefor. The top surface of the frame 24 and the
surface of the phosphor layer 14 to which the moisture-proof
protective layer 16 is bonded are substantially flush with each
other, and a thermoplastic polymer resin is used to thereby
facilitate bonding through heat lamination. Thus, the workability
and the productivity of the phosphor panel 26 are improved.
[0103] In this example, the bonding of the phosphor layer 14 to the
moisture-proof protective layer 16 is not essential but is a
preferable mode.
[0104] An example of a method of producing the phosphor panel 32
will be described.
[0105] First, the frame 24 is fixed on the substrate 12. As shown
in FIG. 4, as a fixing method, the frame 24 is bonded to or fixed
on the surface of the substrate 12 using a heat resistant epoxy
adhesive or the like, for example. In order to improve deposition
position accuracy of the phosphor layer 14, a groove 36
corresponding to the bottom shape of the frame 24 may be formed on
the surface of the substrate 12, and the frame 24 may be fixed
therein as shown in FIG. 5. The frame 24 may be fixed to the
substrate 12 by merely fitting the frame 24 into the groove 36, by
fixing with a heat resistant epoxy resin or the like, or by fitting
into the groove 36 using an adhesive.
[0106] Next, a Kapton tape with a heat resistant adhesive may be
attached onto the frame 24, and an excess portion thereof is cut
off along inside of the frame 24. The phosphor layer 14 is formed
on the substrate 12 with the frame 24. As described above, the
difference between heights of the surface of the phosphor layer 14
and the top surface of the frame 24 is preferably as small as
possible, and the difference is particularly preferably 0.1 mm or
less.
[0107] As in the phosphor panel 26 of FIG. 3, the stimulable
phosphor adhesive layer 28 is formed on the entire surface of the
moisture-proof protective layer 16, and the phosphor layer 14 is
covered with the moisture-proof protective layer 16 having the
stimulable phosphor adhesive layer 28. The stimulable phosphor
adhesive layer 28 is formed such that a sealing portion (that is,
portion corresponding to the sealing adhesive layer 18) between the
frame 24 and the moisture-proof protective layer 16 after sealing
has a width a of 2 mm to 10 mm and a thickness b of 0.5 .mu.m to 20
.mu.m.
[0108] Heat lamination is carried out for bonding together the
moisture-proof protective layer 16, the phosphor layer 14, and the
frame 24 in the same manner as in the method of producing the
phosphor layer 26. The phosphor panel 32 has the frame 24 and has a
small difference between heights of the top surface of the frame 24
and the surface of the phosphor layer 14. Thus, the lamination may
be carried out a predetermined number of times in one
direction.
[0109] The substrate 12 may be heated before sealing of the
phosphor layer 14 with the moisture-proof protective layer 16 as in
the previous examples.
[0110] The phosphor panel of the present invention is basically
structured as described above, but may be provided with a groove
for adhesive into which an adhesive that was not used in forming
the sealing adhesive layer 18/stimulable phosphor adhesive layer 28
penetrates. The position for forming the groove for adhesive is not
particularly limited, and the groove for adhesive need only be
formed at a position corresponding to the sealing adhesive layer 18
or at a position corresponding to a portion that corresponds to the
sealing adhesive layer in the stimulable phosphor adhesive layer
28.
[0111] The phosphor panel having a structure in which the
moisture-proof protective layer 16 is directly bonded to the
substrate 12 as shown in FIGS. 1 to 3 may be provided with a groove
for adhesive 40 at a position corresponding to the sealing adhesive
layer 18 on the substrate 12 as shown in FIG. 6, for example.
[0112] Further, the phosphor panel having a structure in which the
frame 24 is provided and the moisture-proof protective layer 16 is
bonded thereto as shown in FIGS. 4 and 5 may be provided with a
groove for adhesive 44 on the top surface of the frame 24 as shown
in FIG. 7, for example.
[0113] The groove for adhesive 40 is provided to form an escape
route for an excess adhesive and to prevent horizontal spreading or
thick application of the adhesive, thereby facilitating formation
of the sealing adhesive layer 18/stimulable phosphor adhesive layer
28 having a desired shape.
[0114] When the moisture-proof protective layer 16 is bonded to the
frame 24 provided in the phosphor panel of the present invention as
shown in FIGS. 4 and 5, a groove for adhesive into which an excess
amount of an adhesive in fixing the frame 24 on the substrate 12
penetrates may be provided.
[0115] The groove for adhesive may be provided anywhere in the
sealing portion between the frame 24 and the substrate 12. As shown
in FIG. 8, a groove for adhesive 48 may be provided at a position
where the frame 24 is fixed on the surface of the substrate 12, for
example.
[0116] The groove for adhesive 48 can prevent protrusion of the
adhesive outside or inside the frame 24 or non-horizontal fixing of
the frame 24 with respect to the substrate 12 due to accumulation
and solidification of an excess amount of the adhesive.
[0117] The structure having the frame 24 may be provided with both
the groove 44 for an adhesive used in bonding together the frame 24
and the moisture-proof protective layer 16 and the groove 48 for an
adhesive used in fixing the frame 24 onto the substrate 12.
[0118] As described above, the stimulable phosphor panel and the
method of producing the stimulable phosphor panel according to the
present invention have been described. However, the present
invention is not limited to the previous examples, and various
modifications or changes may be obviously made without departing
from the scope of the present invention.
EXAMPLES
[0119] Hereinafter, the present invention will be described in more
detail with reference to specific examples of the present invention
and using the attached drawings. The present invention is obviously
not limited to the following examples.
Example 1
[0120] A phosphor layer 14 composed of CsBr:Eu was formed on a
surface of an aluminum substrate 12 through two-source vacuum
evaporation employing europium bromide as a material for an
activator and cesium bromide as a material for a phosphor,
respectively.
[0121] The both materials were heated in a resistance heating
apparatus employing tantalum crucibles and DC power supplies each
having an output of 6 kW.
[0122] An aluminum substrate (hereinafter, referred to as
substrate) 12 having an area of 450 mm.times.450 mm was set on a
substrate holder of a vacuum evaporation apparatus (vacuum
chamber), and materials were set at respective predetermined
positions. Then, the vacuum chamber was closed and evacuation was
started. A diffusion pump and a cryogenic coil were used for the
evacuation.
[0123] When the degree of vacuum reached 8.times.10.sup.-4 Pa,
argon gas was introduced into the vacuum chamber to adjust the
degree of vacuum to 0.5 Pa. Power was supplied to the crucibles
filled with the respective materials by driving the DC power
supplies to thereby form the phosphor layer 14 on the surface of
the substrate 12 through resistance heating.
[0124] Outputs of the DC power supplies for the both crucibles were
adjusted such that a molar concentration ratio of Eu/Cs was 0.003:1
in the phosphor layer 14, and a film deposition rate was 8
.mu.m/min. During film deposition, the surface of the substrate 12
was directly heated using a halogen lamp.
[0125] The film deposition was terminated when the thickness of the
phosphor layer 14 reached about 710 .mu.m, and the substrate 12 was
taken out from the vacuum chamber. The thickness thereof was
controlled based on the results of previously performed
experiments.
[0126] Next, the substrate 12 in which film deposition was
terminated was subjected to annealing treatment in a nitrogen
atmosphere at 200.degree. C. for 2 hours.
[0127] Meanwhile, an SiO.sub.2 film was formed to a thickness of
100 nm on a PET film having a thickness of 6 .mu.m through
sputtering. A hybrid layer of PVA and SiO.sub.2 was formed thereon
to a thickness of 600 nm through a sol-gel process such that the
ratio of PVA to SiO.sub.2 was 1:1. Further, an SiO.sub.2 film was
formed to a thickness of 100 nm on the hybrid layer through
sputtering, to thereby prepare the moisture-proof protective layer
16.
[0128] An epoxy resin EP001 (available from Cemedine Co., Ltd.;
moisture permeability of 783 g/m.sup.2day (at 40.degree. C. and
relative humidity of 90%)) serving as the sealing adhesive layer 18
was applied onto the periphery portion on the substrate 12 using a
dispenser. The epoxy resin was applied such that the sealing
adhesive layer 18 after sealing had a width of 5 mm and a thickness
of 7 .mu.m. The moisture permeability of the epoxy resin was
measured by: forming a resin sheet to a thickness of 100 .mu.m
after curing; and measuring the moisture permeability of the sheet
in accordance with the Dish Method of JIS Z 0208.
[0129] Next, the phosphor layer 14 was covered with the
moisture-proof protective layer 16 cut into a size of 420
mm.times.420 mm such that an SiO.sub.2 layer side faced the
phosphor layer 14. A press mold (pressing surface made of rubber)
having a shape corresponding to the sealing adhesive layer 18 was
used to press the moisture-proof protective layer 16 against the
sealing adhesive layer 18, and this state was maintained. The
phosphor layer 14 was thus sealed to thereby produce the phosphor
panel 10 shown in FIG. 1.
Comparative Examples 1 to 4
[0130] The phosphor panel 10 was produced in the same manner as in
Example 1 except that: the thickness of the sealing adhesive layer
18 was changed to 25 .mu.m (Comparative Example 1) or 0.4 .mu.m
(Comparative Example 2); or the width of the sealing adhesive layer
18 was changed to 1 mm (Comparative Example 3) or 12 mm
(Comparative Example 4).
Example 2
[0131] The phosphor layer 14 was formed on the surface of the
substrate 12 in the same manner as in Example 1.
[0132] Next, an epoxy resin (the same resin as that of Example 1)
forming the sealing adhesive layer 18 was applied onto the
substrate 12 in the same manner as in Example 1 using a
dispenser.
[0133] Meanwhile, a polyester-based resin (VYLON 300, available
from Toyobo Co., Ltd.; moisture permeability of 139 g/m.sup.2day
(at 40.degree. C. and relative humidity of 90%)) was applied onto a
central region (400 mm.times.400 mm) of the same moisture-proof
protective layer 16 (surface of SiO.sub.2 layer) as that of Example
1, to thereby form the sealing adhesive layer 18 having a thickness
of 1.2 .mu.m. The moisture permeability of the polyester-based
resin was measured in the same manner as for the epoxy resin of
Example 1.
[0134] The phosphor layer 14 was covered with the moisture-proof
protective layer 16 having the stimulable phosphor adhesive layer
22, and heat lamination was carried out at 100.degree. C. and a
linear velocity of 0.5 ml/min using a laminate material, to thereby
bond together the moisture-proof protective layer 16 and the
phosphor layer 14. The heat lamination was carried out 4 times in
the same direction through a laminating machine.
[0135] After the moisture-proof protective layer 16 and the
phosphor layer 14 were bonded together, the moisture-proof
protective layer 16 and the substrate 12 were bonded together
through the sealing adhesive layer 18 in the same manner as in
Example 1. The phosphor layer 14 was thus sealed to thereby produce
the phosphor panel 20 shown in FIG. 2.
Example 3
[0136] The phosphor layer 14 was formed on the surface of the
substrate 12 in the same manner as in Example 1.
[0137] Meanwhile, a polyester-based resin (the same resin as that
of Example 2) was applied onto the entire surface (SiO.sub.2 layer
surface) of the same moisture-proof protective layer 16 as that of
Example 1, to thereby form the stimulable phosphor adhesive layer
28 having a thickness of 1.2 .mu.m.
[0138] Next, the phosphor layer 14 was covered with the
moisture-proof protective layer 16 such that the stimulable
phosphor adhesive layer 28 on the moisture-proof protective layer
16 faced the phosphor layer 14. Heat lamination was carried out
through a laminating machine 4 times in one direction in the same
manner as in Example 2 and then 4 times in a direction obtained by
rotating by 90.degree., to thereby bond together the moisture-proof
protective layer 16, the phosphor layer 14, and the substrate 12.
The phosphor layer 14 was sealed to thereby produce the phosphor
panel 26 shown in FIG. 3.
Example 4
[0139] An aluminum frame having outer dimensions of 412
mm.times.412 mm, a width of 5 mm, and a thickness of 0.7 mm was
bonded onto the same substrate 12 as that of Example 1 using a heat
resistant epoxy adhesive (Aremco-Bond 526 N, available from Audec
Corporation).
[0140] Next, a Kapton tape with a heat resistant adhesive (Scotch
Kapton tape 5413, available from 3M) was attached onto the bonded
aluminum frame 24, and an excess portion of the tape was cut off
along inner sides of the aluminum frame 24. The phosphor layer 14
was formed to a thickness of about 710 .mu.m on the substrate 12
inside the frame in the same manner as in Example 1.
[0141] After formation of the phosphor layer 14, the attached
Kapton tape was peeled off, to thereby obtain the substrate 12
having the phosphor layer 14 formed only inside the aluminum frame
24. The difference between heights of the surface of the phosphor
layer 14 and the top surface of the aluminum frame 24 was 10 .mu.m
or less.
[0142] Meanwhile, the same adhesive as that of Example 3 was
applied onto the same moisture-proof protective layer 16 as that of
Example 1, to thereby form the stimulable phosphor adhesive layer
28 having a thickness of 1.2 .mu.m.
[0143] Next, the moisture-proof protective layer 16 was placed on
the phosphor layer 14 and the frame 24 such that the stimulable
phosphor adhesive layer 28 faced the phosphor layer 14. Heat
lamination was carried out in the same manner as in Example 2 and
the phosphor layer 14 was sealed to thereby produce the phosphor
panel 32 shown in FIG. 4. Heat lamination was carried out 4 times
in one direction through a laminating machine.
Example 5
[0144] The phosphor panel 32 was produced in the same manner as in
Example 4 except that the substrate 12 was preheated to 100.degree.
C. before lamination and lamination was carried out once in one
direction.
Comparative Examples 5 and 6
[0145] The phosphor panel 32 was produced in the same manner as in
Example 4 except that the thickness of the stimulable phosphor
adhesive layer 28 was changed to 0.4 .mu.m (Comparative Example 5)
or 25 .mu.m (Comparative Example 6).
[0146] The thickness b of the sealing adhesive layer 18, the
sealing width a, and the difference in height between the surface
of the phosphor layer 14 and the sealing surface in each obtained
phosphor panel was measured as described below.
[Thickness]
(Thickness of Sealing Adhesive Layer 18)
[0147] The difference in height between the surface of the
substrate 12 without the moisture-proof protective layer 16 and the
surface of the moisture-proof protective layer 16 in the vicinity
of the substrate 12 was measured using a 3D measuring machine
(Non-contact 3D measuring machine, manufactured by Mitutoyo
Corporation). Then, the thickness of the moisture-proof protective
layer 16 measured in advance was subtracted from the height
difference to thereby obtain a value representing the thickness of
the sealing adhesive layer 18. The measurement was carried out at
12 points for each sample, and an average value was determined.
(Thickness of Stimulable Phosphor Adhesive Layer)
[0148] After a selected adhesive was applied onto the surface of
the moisture-proof protective layer 16, the total thickness of the
moisture-proof protective layer 16 including the stimulable
phosphor adhesive layer was measured (thickness meter K351C,
manufactured by Anritsu Corporation). The thickness of the
moisture-proof protective layer 16 measured in advance was
subtracted from the total thickness to thereby obtain a value
representing the thickness of the stimulable phosphor adhesive
layer. The measurement was carried out at 12 points for each sample
of 400 mm.times.400 mm, and an average value was determined.
[Sealing Width]
[0149] The width of the sealing portion of each sample was measured
using a steel rule (JIS 1st grade) at 12 points, and an average
value was determined.
[Difference in Height Between Surface of Phosphor Layer and Sealing
Surface]
[0150] Before the moisture-proof protective layer 16 was provided,
the difference in height between an edge of the surface of the
phosphor layer 14 and the sealing surface in the vicinity of the
layer 14 was measured at 12 points for each sample using a 3D
measuring machine (Non-contact 3D measuring machine, manufactured
by Mitutoyo Corporation), and an average value was determined.
[0151] Table 1 shows the thickness b of the sealing adhesive layer
18, the sealing width a, the height difference, the conditions for
forming the phosphor panel, the materials, and the like of each of
Examples and Comparative Examples. TABLE-US-00001 TABLE 1 Sealing
Peripheral adhesive Adhesive layer Sealing Height Phosphor layer/
Number of sealing layer thickness [.mu.m] width [mm] difference
[.mu.m] protective layer Panel preheating lamination Example 1
Protective Epoxy 7 .+-. 1 5 .+-. 0.5 710 .+-. 10 Unbonded None None
layer/substrate Example 2 Protective Epoxy 7 .+-. 2 5 .+-. 0.5 710
.+-. 12 Polyester-based None 1 direction .times. 4 layer/substrate
times Example 3 Protective Polyester- 1.2 .+-. 0.2 5 .+-. 0.5 710
.+-. 8 Polyester-based None 2 layer/substrate based (doubles as
sealing directions .times. 4 adhesive layer) times Example 4
Protective Polyester- 1.2 .+-. 0.2 5 .+-. 0.0 10 .+-. 8
Polyester-based None 1 direction .times. 4 layer/sealing based
(doubles as sealing times frame/substrate adhesive layer) Example 5
Protective Polyester- 1.2 .+-. 0.2 5 .+-. 0.0 10 .+-. 7
Polyester-based 100.degree. C. 1 direction .times. 1 layer/sealing
based (doubles as sealing time frame/substrate adhesive layer)
Comparative Protective Epoxy 25 .+-. 2 5 .+-. 0.5 710 .+-. 8
Unbonded None None Example 1 layer/substrate Comparative Protective
Epoxy 0.4 .+-. 0.05 5 .+-. 0.5 710 .+-. 12 Unbonded None None
Example 2 layer/substrate Comparative Protective Epoxy 7 .+-. 1 1
.+-. 0.2 710 .+-. 12 Unbonded None None Example 3 layer/substrate
Comparative Protective Epoxy 7 .+-. 1 12 .+-. 0.5 710 .+-. 14
Unbonded None None Example 4 layer/substrate Comparative Protective
Polyester- 0.4 .+-. 0.05 5 .+-. 0.0 10 .+-. 6 Polyester-based
100.degree. C. 1 direction .times. 1 Example 5 layer/sealing based
(doubles as sealing time frame/substrate adhesive layer)
Comparative Protective Polyester- 25 .+-. 1 5 .+-. 0.0 10 .+-. 8
Polyester-based 100.degree. C. 1 direction .times. 1 Example 6
layer/sealing based (doubles as sealing time frame/substrate
adhesive layer)
[0152] The moisture permeability and the peeling strength of the
sealing portion were measured as described below in each of the
various phosphor panels obtained.
[Moisture Permeability of Sealing Portion]
[0153] The moisture permeability of the moisture-proof protective
layer 16 was measured under the conditions of 40.degree. C. and a
relative humidity of 90% using a water vapor permeation analyzer
(Model 7000, manufactured by Illinois Instruments, Inc.). The
moisture permeability obtained was represented by .alpha.
(g/m2day).
[0154] The phosphor layer 14 and the adhesive layer (sealing
adhesive layer 18, or sealing adhesive layer 18 and stimulable
phosphor adhesive layers 22 and 28) were formed on the surface of
an aluminum substrate having a size of 450 mm.times.450 mm and a
thickness of 3 mm in the same manner as in Examples and Comparative
Examples. The phosphor layer 14 was sealed with the moisture-proof
protective layer 16, to thereby prepare a sample for measurement of
moisture permeability. The substrate 12 had a small thickness for
measuring the moisture permeability through weight change. A
substrate having a thickness of 10 mm has a large weight, and it
takes a long period of time until the weight increase due to
moisture absorption can be measured. However, the moisture
absorption is not changed in any way even with a thin
substrate.
[0155] The weight of the sample was measured (PG2002-2,
manufactured by Mettler), and the obtained weight was represented
by an initial weight .beta.(g).
[0156] Then, the sample was charged into a thermostatic bath of
40.degree. C. and a relative humidity of 90%, and was left to stand
for 100 days. The weight of the sample after 100 days was measured
in the same manner as before, and the weight obtained as the weight
after the passage of time was represented by .gamma.(g).
[0157] The moisture absorption from the sealing portion was
determined through calculation from the weight increase of the
sample and the moisture permeability of the moisture-proof
protective layer. The moisture absorption from the sealing portion
was represented by T(g/day). The moisture absorption from the
sealing portion can be represented by the following equation:
T=(.gamma.-.beta.)/100-(.alpha..times.S) in which S(m.sup.2)
represents an area of the moisture-proof protective layer.
[0158] Table 2 shows the results.
[Peeling Strength of Sealing Portion]
[0159] An aluminum sheet (width of 10 mm, length of 100 mm, and
thickness of 1 mm) formed of the same material as that of the
substrate of each Example was prepared. A linear sealing adhesive
layer 18 having the same width and the same thickness as those of
each Example or Comparative Example was formed, and was attached
onto the moisture-proof protective layer 16. Similarly, the
moisture-proof protective layer of each Example was attached onto
the aluminum sheet through pressing using a pressing mold or
through heat lamination in the same manner and under the same
conditions as those of each Example. A portion of the
moisture-proof protective layer protruding from the aluminum sheet
was cut off using a cutter.
[0160] An edge (about 10 mm) of the attached moisture-proof
protective layer was peeled off, and the peeling strength of the
moisture-proof protective layer was measured at 180.degree. C.
using a tensile tester (Compact table-top material tester ET TEST,
manufactured by Shimadzu Corporation). Table 2 shows the
results.
[0161] The sensitivity (relative value) of each phosphor panel was
evaluated based on the moisture permeability and the peeling
strength of the sealing portion. For overall evaluation of the
relative sensitivity, 1 refers to "not practical", and 2 refers to
"favorable for practical use". Further, 3 represents "particularly
favorable for practical use", and 4 represents "optimum level for
practical use". Table 2 shows the results of the overall
evaluation. TABLE-US-00002 TABLE 2 Permeation amount in Peeling
sealing strength in portion sealing Number of [g/day] portion
Overall lamination (size of 45 cm.sup..quadrature.) [N/cm]
evaluation Example 1 None 0.0002 or 2 2 less Example 2 1 direction
.times. 4 0.0002 or 2 3 times less Example 3 2 0.0002 or 1 3
directions .times. 4 less times Example 4 1 direction .times. 4
0.0002 or 1 3 times less Example 5 1 direction .times. 1 0.0002 or
1.3 4 time less Comparative None 0.006 2 1 Example 1 Comparative
None -- 0.15 1 Example 2 Comparative None 0.02 2 1 Example 3
Comparative None 0.0002 or 2 1 Example 4 less Comparative 1
direction .times. 1 -- 0.3 1 Example 5 time Comparative 1 direction
.times. 1 0.004 20.5 1 Example 6 time
[0162] Table 2 reveals that the phosphor panel of Example 1 has
favorable workability and practicality. The phosphor panel of
Example 2 has the moisture-proof protective layer 16 and the
phosphor layer 14 bonded together, and thus has excellent
durability. The phosphor panel of Example 3 has the sealing
adhesive layer 18 also serving as an adhesive layer between the
moisture-proof protective layer 16 and the phosphor layer 14, and
thus has particularly favorable workability. The phosphor panel of
Example 4 has a frame and can be formed through heat lamination
only in one direction using a laminating machine, and thus has
further favorable workability compared with that of the phosphor
panel of Example 3. The phosphor panel of Example 5 is formed
through heat bonding, and thus has very favorable workability and
practicality compared with those of the phosphor panel of Example
4. In other words, the phosphor panels of Examples 1 to 5 in the
present invention all have excellent moisture-proof property,
strength, and overall evaluation.
[0163] Meanwhile, the phosphor panel of Comparative Example 1 has
too thick a sealing adhesive layer 18 which results in high
moisture permeability. The moisture permeability of the sealing
portion becomes the moisture permeability of the moisture-proof
protective layer, and thus the phosphor panel of Comparative
Example 1 is not practical. The phosphor panel of Comparative
Example 2 has too thin a sealing adhesive layer 18 which results in
an insufficient sealing adhesive strength, and thus is not
practical. The phosphor panel of Comparative Example 3 has too
narrow a sealing adhesive layer which results in unfavorable
sealing and large moisture permeation, and thus is not practical.
The phosphor panel of Comparative Example 4 has good results in
moisture permeability of the sealing portion and peeling strength
of the sealing portion, but has too large a sealing width which
results in a small image pickup surface with respect to the size of
the phosphor panel and a large size of the phosphor panel for
ensuring an image pickup surface with a required size. Thus, the
phosphor panel of Comparative Example 4 is not practical and has an
overall evaluation of 1. The phosphor panel of Comparative Example
5 has a thin stimulable phosphor adhesive layer which results in an
insufficient sealing adhesive strength and peeling thereof, and
thus is not practical. The phosphor panel of Comparative Example 6
has a narrow stimulable phosphor adhesive layer, a large moisture
permeability of the sealing portion, and a thick stimulable
phosphor adhesive layer at the interface with the phosphor layer.
Thus, the sharpness of the image deteriorates and the phosphor
panel of Comparative Example 6 is not practical.
* * * * *