JP2002116259A - Applied electric field type x-ray detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a highly reliable detector without decrease in mechanical strength, such as cracks or warpages under low-temperature and high-temperature environments, the decrease in sensor characteristics due to the decrease in resistance caused by the crystallization of selenium, and further discharge breakdown or the like due to the application of a high voltage, without having to use materials, such as resin and adhesives, or protection layers. SOLUTION: In the electric field application type X-ray detector, where an X-ray latent image is formed by directly applying an electric field to an X-ray light sensitive layer, carriers that are generated by applying the electric field and X rays are allowed to run in a sensor, and obtained electric charges are subjected to image processing; an X-ray photoconductive layer 2 is provided on a substrate 1, where an electric charge collection electrode is formed on a glass plate, and a protection layer 4 containing a thermosetting silicide that is generated by performing the hydrolysis of a silane compound is provided on the X-ray photoconductive layer 2 and an upper electrode 3; thus easily obtaining a high electrical resistance which covers with almost no difference in the thermal coefficient of expansion with a glass substrate and having without the problems of warpages and cracks due to environmental changes, and hence very much improving durability to mechanical, physical, and electrical stresses required for long operation to a field requiring a flat surface and a large area.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray detector applied with an electric field, and more particularly, to an X-ray photoconductive layer provided on a substrate having a charge collecting electrode formed on a glass plate. The present invention relates to an electric field applied X-ray detector comprising a protective layer containing a thermosetting silicon compound formed by hydrolyzing a silane compound on a layer.

[0002]

2. Description of the Related Art Detectors using radiation such as X-rays and γ-rays have been widely used in recent years for medical and industrial purposes. In the field of photography, digitization of DSA, CR (DR), etc., and more recently, digitization of ultrasonic devices have attracted attention.

[0003] The background of digitization is image quality comparable to that of an analog system, reduction in the price of imaging equipment, simplification of operation, and the like. In view of the demands of the industrial field such as efficiency, it is desired to establish an X-ray image recording and reading method with further improvement in quality and cost reduction.

A so-called stimulable fluorescent film which emits visible light to accumulated X-ray energy to generate fluorescence has been proposed for recording and detecting an X-ray image. However, there is a time delay in image processing. Real-time image processing is not possible.

[0005] Further, a system is used in which an electric field is applied to an X-ray photo-con- erator layer to directly convert the X-ray image sensor into an electric signal by utilizing the peculiar properties of amorphous Se as a photoreceptor for an X-ray image sensor. In this method, a high electric field is directly applied to the X-ray photocon layer, the intensity of X-rays incident on the sensor is extracted in a plane, and the object to be observed is a human body. Therefore, there is a restriction that a large area is required, and a patterned substrate electrode is formed on an insulating substrate such as glass.

In addition, cracks and warpages are liable to occur due to thermal stress such as low temperature and high temperature such as a difference in expansion and contraction of the area resulting from a difference in thermal expansion coefficient between the glass substrate and the photoconductive layer.
Changes in the electrical properties of the photoconductive layer, such as a decrease in the thermal volume resistance of the photoconductor due to long-term storage or a decrease in the surface resistance due to air, water, etc., cause deterioration due to a continuously applied high electric field.

In order to solve such problems, coating with a surface protective agent is conceivable. When a polymer compound such as polycarbonate or acrylic resin is used as the surface protective agent, a predetermined surface resistance is obtained, but glass is used. Due to the difference in the coefficient of thermal expansion from the substrate, cracks and warpage in the case of a large area cannot be avoided.

[0008]

As described above, problems such as mechanical strength such as cracking and warping in low-temperature and high-temperature environments, degradation of sensor characteristics due to crystallization of selenium, and discharge breakdown due to application of high voltage. Thus, a highly reliable detector could not be obtained, but it is an object of the present invention to solve this.

[Means for Solving the Problems]

The present inventors have conducted intensive studies to solve the above problems, and as a result, prepared a specific silane compound as a silane coupling agent in combination, hydrolyzed, applied to an X-ray detector and compared. By curing at a very low temperature,
The present inventors have found that an X-ray detector having sufficient hardness, hardly causing discharge breakdown, and being able to withstand long-term operation with environmental temperature change, and having high reliability can be obtained, and completed the present invention. The curing of the hydrolyzate of the silane coupling agent is carried out by a dehydration condensation reaction to form a siloxane structure having a linear bond of Si-O-Si, and sandwiched between homogeneous materials having the same thermal expansion coefficient and electrical properties as the substrate glass. As a result, high durability is obtained. If glass is further adhered thereon, higher durability can be achieved.

That is, according to the present invention, an electric field is directly applied to the X-ray photosensitivity layer to form an X-ray latent image, carriers generated by the electric field and X-ray irradiation are caused to travel in the sensor, and the obtained charges are subjected to image processing. In an X-ray detector, the detector is formed by providing an X-ray photoconductive layer on a substrate having a charge collecting electrode formed on a glass plate, and hydrolyzing a silane compound on the X-ray photoconductive layer. It is an object of the present invention to provide an electric field application type X-ray detector comprising a protective layer containing a thermosetting silicon compound.

In the present invention, the silane compound may be at least one epoxy silane compound selected from the following group A, at least one alkoxyalkyl silane compound selected from the following group B, and selected from the following group C: It is another object of the present invention to provide the above-mentioned electric field application type X-ray detector, which is at least one kind of aminosilane compound.

In the above general formula, R ¹ is a straight or branched alkyl having 6 or less carbon atoms, R ² is a straight or branched alkyl having 4 or less carbon atoms, and R ³ is 4 or more carbon atoms.
The following linear or branched alkyl or alkoxy, R ⁴ is linear or branched alkyl having 8 or less carbon atoms, R ⁵ is linear or branched alkyl having 2 to 4 carbon atoms, and n is 3 or less. Is an integer.

The compound represented by the above general formula includes A
For the groups, β-glycidoxyethylpropyldipropoxysilane, β-glycidoxyethylpropyldibutoxysilane, γ-glycidoxyethylpropyldimethoxysilane, γ-glycidoxyethylpropyldiethoxysilane, γ-glycidyl Sidoxyethylpropyldiproxysilane, γ-glycidoxyethylpropyldibutoxysilane and the like.

Group B includes monomethyltrimethoxysilane, dimethyldimethoxysilane, monomethyltriethoxysilane, dimethyldiethoxysilane, monoethyltrimethoxysilane, diethyldimethoxysilane, monoethyltriethoxysilane, diethyldiethoxysilane, tetramethoxysilane There are silane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane and the like.

Group C includes aminomethyltrimethoxysilane, aminomethyltriethoxysilane, aminomethylpropoxysilane, aminopropyltrimethoxysilane, aminopropyltriethoxysilane, aminopropyltributoxysilane, N-β-aminoethyl- γ-
Examples include aminopropyltrimethoxysilane.

The composition ratio is preferably such that 2 to 10 parts by volume of the compounds of Group A, B and C are used, and 1 to 6 parts by volume of water. After selecting and mixing at least one of each of the silane compounds from Group A to Group C, hydrolysis is performed by adding water, and if desired, an organic solvent such as methanol or ethanol is immediately added after the completion of the hydrolysis. In addition, the concentration of the hydrolysis is adjusted.

In the present invention, a catalyst is not required for the hydrolysis, and the hydrolysis reaction proceeds only by adding pure water to the mixture of the silane compounds and stirring, and the hydrolysis time is very short.

The organic solvent to be added after the hydrolysis is preferably a hydrophilic one, and methanol, ethanol, propanol, dioxane, methyl cellosolve, ethyl cellosolve and the like can be used. The addition amount of these organic solvents is preferably from 50 to 300 parts by volume. An organic solvent solution is applied on the photoconductive layer and cured by heating. Heating temperature 20-8
Cures at 0 ° C. within one hour. Curing at such a low temperature is extremely advantageous in the case where the photoconductive layer is formed of amorphous selenium or the like, in order to prevent photosensitive performance due to crystallization of selenium.

Further, the silane compound of the present invention has high adhesiveness to an insulating material such as glass or a resin plate, so that it can be used as an intermediate material. The thickness of the protective layer in the present invention is not particularly limited.
mm is preferred.

In the present invention, in order to form a protective layer by hydrolysis of the silane compound, a fixed amount of each of the above-mentioned three types of silane compounds is added so that each of the silane compounds becomes stoichiometrically simultaneously with hydrolysis. The polymer layer is formed by dehydration condensation to form a strong polymer layer in which silicon and oxygen are covalently bonded.

For the X-ray detector of the present invention, a glass substrate with electrodes such as a TFT (thin film transistor) and a comb electrode is used. The X-ray photoconductive layer on the substrate is made of an inorganic photoconductor such as selenium, a selenium telluride compound, a selenium arsenide compound, cadmium sulfide, zinc oxide, amorphous silicon, and the upper electrode is made of a conductive material such as gold, aluminum, and nickel. A barrier layer made of a metal oxide such as aluminum oxide, a metal sulfide such as antimony sulfide, or a polymer material such as polyurethane, cellulose, or polycarbonate may be provided between the photoconductor and the substrate or the upper electrode. . Further, between the substrate and the upper electrode, a photoconductor and a barrier layer or a pattern electrode or the like may be laminated in a plural number to form a function separation type.

A highly durable protective layer containing a silane compound as a main component is formed on these photoconductive layers. As a forming method, there are a dip coating method, a spinner method, a spray method, a Langmuir project method and the like. In the hydrolysis of the groups A, B and C, acids such as hydrochloric acid, sulfuric acid and acetic acid and salts thereof may be used as a catalyst. After the hydrolysis reaction, methanol, ethanol, dioxane, methyl cellosolve,
The concentration and the crosslinking reaction may be adjusted using an organic solvent such as ethyl cellosolve. INDUSTRIAL APPLICABILITY The electric field application type X-ray detector of the present invention can provide high-quality images and is useful not only for medical purposes but also for various industrial uses.

1 to 3 show the configuration of the present invention. 1
Is a glass substrate with electrodes, 2 is a selenium layer, 3 is an upper electrode, 4
Represents a protective layer, and 5 represents a glass plate. FIG. 4 shows a temperature profile, in which the vertical axis represents temperature and the horizontal axis represents time.

[0024]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the present invention is limited to the following Examples without departing from the scope of the invention.

Example 1 2.4 parts by volume of β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 4.8 parts by volume of monomethyltrimethoxysilane, and 2.4 parts by volume of γ-aminopropyltriethoxysilane were mixed. Then, 1.2 parts by volume of water was added thereto, and the mixture was vigorously stirred at room temperature to allow a hydrolysis reaction to proceed to obtain a coating liquid for forming a protective layer. Next, a 500 μm-thick film was formed on a charge collecting electrode in which ITO was formed in a matrix on a glass substrate.
And then a 0.1 μm gold thin film was formed. The coating liquid for forming a protective layer is applied thereon, and the coating liquid is applied at 40 ° C. for 24 hours.
After heating for a time, a transparent protective layer was formed to obtain a protective layer-formed X-ray detector.

Example 2 5.2 parts by volume of γ-glycidoxyethylpropyltrimethoxysilane, 6.4 parts by volume of dimethyldimethoxysilane, 2.4 parts by volume of N-β (aminoethyl) γ-aminopropyltrimethoxysilane And 2.2 parts by volume of water were mixed to prepare a coating liquid in the same manner as in Example 1. The obtained coating liquid was applied in the same manner as in Example 1 to obtain a protective layer forming X-ray detector.

Example 3 4.2 parts by volume of β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3.8 parts by volume of dimethyldimethoxysilane, 4.4 parts by volume of γ-aminopropyltriethoxysilane, water 2 2 parts by volume were mixed to prepare a coating liquid in the same manner as in Example 1. The obtained coating liquid was applied in the same manner as in Example 1 to obtain a protective layer forming X-ray detector.

Example 4 5.8 parts by volume of γ-glycidoxypropyltrimethoxysilane, 1.2 parts by volume of tetramethoxysilane, 4.6 parts by volume of N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane, A coating liquid was prepared in the same manner as in Example 1 by mixing 3.8 parts by volume of water. The obtained coating liquid was applied in the same manner as in Example 1 to obtain a protective layer forming X-ray detector.

Example 5 2.6 parts by volume of β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 4.8 parts by volume of methoxytrimethylsilane, 2.8 parts by weight of aminomethyltrimethoxysilane
A coating solution was prepared in the same manner as in Example 1 by mixing 4.2 parts by volume of water and 4.2 parts by volume of water. The obtained coating liquid was applied in the same manner as in Example 1 to obtain a protective layer forming X-ray detector.

EXAMPLE 6 2.4 parts by volume of β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 4.8 parts by volume of monomethyltrimethoxysilane and 2.4 parts by volume of γ-aminopropyltriethoxysilane were mixed. Then, 1.2 parts by volume of water was added thereto, and the mixture was vigorously stirred at room temperature to allow a hydrolysis reaction to proceed to obtain a coating liquid for forming a protective layer. Next, a 500 μm-thick film was formed on a charge collecting electrode in which ITO was formed in a matrix on a glass substrate.
And then a 0.1 μm gold thin film was formed. The coating liquid for forming a protective layer was applied thereon, and a glass having only a high-voltage application portion cut out was placed on the protective layer, and heated at 40 ° C. for 24 hours to obtain an X-ray detector for forming a protective layer.

Comparative Example 1 An X-ray detector was prepared in the same manner as in Example 1 except that no protective layer was formed.

COMPARATIVE EXAMPLE 2 Instead of the three silane compounds of Example 1, 100 parts by volume of polycarbonate was dissolved in 100 parts by volume of chloroform while stirring to prepare a coating liquid for forming a protective layer. An X-ray detector was created by the method.

Comparative Example 3 Instead of the three silane compounds of Example 1, 100 parts by volume of polymethacrylate (PMMA) were dissolved in 100 parts by volume of tetrahydrofuran (THF) with stirring. To this, 30 parts by volume of β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane was added and mixed well to prepare a solution. Then, an X-ray detector was prepared in the same manner as in Example 1. (In this reaction, no condensation polymerization reaction occurs due to hydrolysis.)

Table 1 shows the evaluation results of the examples and comparative examples. The evaluation items and contents are as follows. a) Environmental test: As shown in FIG. 4, a test was performed with a temperature profile up and down from a room temperature of 25 ° C.
The degree of warpage was evaluated. b) Life test: X-ray continuous irradiation, 1
The applied voltage was increased at V / μm / h, and the electric field at which the discharge was destroyed was taken as a value. The X-ray irradiation conditions at this time include an X-ray tube voltage of 1
At 20 kV, the dose is 18 R / min. c) Peeling test; a cellophane tape is stuck on the outermost surface layer (protective layer) and vigorously peeled off to evaluate the adhesive strength at the interface between the glass substrate with electrodes and the photoconductive layer. d) Hardness test; a known pencil hardness measuring method by

[0035]

[Table 1]

[0036]

According to the present invention, since the surface of the X-ray detector has a siloxane structure due to the hydrolysis and dehydration condensation reaction of the silane coupling agent, there is almost no difference in the thermal expansion coefficient between the X-ray detector and the glass substrate. And the like, and a high electric resistance film can be easily obtained. For the field requiring a large area in a plane, the durability against mechanical, physical and electrical stress required for long-term operation can be remarkably improved.

[Brief description of the drawings]

FIG. 1 shows a configuration diagram of the present invention.

FIG. 2 shows another configuration diagram of the present invention.

FIG. 3 shows still another configuration diagram of the present invention.

FIG. 4 shows a temperature profile.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Glass substrate with an electrode 2 Selenium layer 3 Upper electrode 4 Protective layer 5 Glass plate

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[Procedure amendment]

[Submission date] November 29, 2001 (2001.11.
29)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claim 2

[Correction method] Change

[Correction contents]

Embedded image

Embedded image Group B;

Embedded image Group C;

Embedded image

Embedded image However, in the above general formula, R ¹ is straight-chain or branched alkylene having 6 or less carbon atoms, R ² is a straight-chain or branched alkyl having 4 or less carbon atoms, R ³ is a straight chain having 4 or less carbon atoms or a branched alkyl or alkoxy, R ⁴ is the following straight-chain or branched alkylene 8 carbon atoms, R ⁵ is a straight-chain or branched alkylene of from 2 carbon atoms up to 4, n
Is an integer of 3 or less.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction contents]

In the present invention, the silane compound may be at least one epoxy silane compound selected from the following group A, at least one alkoxyalkyl silane compound selected from the following group B, and selected from the following group C: It is another object of the present invention to provide the above-mentioned electric field application type X-ray detector, which is at least one kind of aminosilane compound. Group A;

Embedded image

Embedded image Group B;

Embedded image Group C;

Embedded image

Embedded image

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction contents]

[0012] However, in the above general formula, R ¹ is straight-chain or branched alkylene having 6 or less carbon atoms, R ² is a straight-chain or branched alkyl having 4 or less carbon atoms, R ³ is 4 or less carbon atoms linear or a branched alkyl or alkoxy, R ⁴ is a straight-chain or branched alkylene of 8 carbon atoms, straight-chain or branched alkyl les of R ⁵ from 2 to 4 carbon atoms
And n is an integer of 3 or less.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0013

[Correction method] Change

[Correction contents]

The compound represented by the above general formula includes A
For the groups, β-glycidoxyethylpropyldipropoxysilane, β-glycidoxyethylpropyldibutoxysilane, γ-glycidoxyethylpropyldimethoxysilane, γ-glycidoxyethylpropyldiethoxysilane, γ-glycidyl Sid carboxyethyl propyl dipropionate Po Kishishiran, there is γ- glycidoxypropyltrimethoxysilane ethylpropyl dibutoxy silane.

[Procedure amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0015

[Correction method] Change

[Correction contents]

[0015] For Group C, aminomethyl trimethoxy silane, aminomethyl triethoxysilane, aminomethyl tripropoxysilane, aminopropyltrimethoxysilane, aminopropyltriethoxysilane, aminopropyl tributoxy silane, N-beta-aminoethyl −
γ-aminopropyltrimethoxysilane and the like.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 31/0248 H01L 31/00 A 31/0264 31/08 H 31/108 L H04N 5/32 31/10 CF term (reference) 2G088 EE01 EE27 FF02 FF14 GG21 JJ10 JJ35 JJ37 LL11 4M118 AA08 AA10 BA05 CA14 CA32 CB05 CB06 CB14 FB13 GA10 5C024 AX11 CY47 5F049 MA05 MB03 MB05 NA07 NB05 RA02 AA1A08 AB01 EA04 EA08 GA02 HA12 LA08

Claims (2)

[Claims] 1. An X-ray detection device for applying an electric field directly to an X-ray photosensitivity layer to form an X-ray latent image, causing carriers generated by the electric field and X-ray irradiation to travel in a sensor, and performing image processing on the obtained charges. A detector provided with an X-ray photoconductive layer on a substrate having a charge collecting electrode formed on a glass plate;
An electric field application type X-ray detector, comprising a protective layer containing a thermosetting silicon compound formed by hydrolyzing a silane compound on a linear photoconductive layer. 2. The method according to claim 1, wherein the silane compound is at least one epoxy silane compound selected from the following group A, at least one alkoxyalkylsilane compound selected from the following group B, and at least one selected from the following group C: The electric field application type X-ray detector according to claim 1, which is a kind of aminosilane compound. However, in the above general formula, R ¹ is a straight or branched alkyl having 6 or less carbon atoms, R ² is a straight or branched alkyl having 4 or less carbon atoms, and R ³ is a straight or branched alkyl having 4 or less carbon atoms. R ⁴ is a linear or branched alkyl having 8 or less carbon atoms, R ⁵ is a linear or branched alkyl having 2 to 4 carbon atoms, and n is an integer of 3 or less.