JP2005276975A - Manufacturing method of photoconductive layer constituting radiation imaging panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture a photoconductive layer consisting of bismuth oxide system compound oxide with low electrical noise, and having high collecting effect of electric charges generated. <P>SOLUTION: Bi<SB>12</SB>MO<SB>20</SB>precursor liquid (where, M is at least one sort of Ge, Si, and Ti.) is obtained by reacting bismuth salt and metal alkoxide under acid conditions. The obtained Bi<SB>12</SB>MO<SB>20</SB>precursor liquid is applied to a support body. The Bi<SB>12</SB>MO<SB>20</SB>precursor liquid applied to the support body is calcinated, so that the photoconduction layer consisting of Bi<SB>12</SB>MO<SB>20</SB>sintering film is manufactured. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a radiation imaging panel suitable for application to a radiation imaging apparatus such as an X-ray, and more particularly to a method for producing a photoconductive layer constituting the radiation imaging panel.

  Conventionally, in medical X-ray photography, a photoconductive layer sensitive to X-rays has been used as a photoconductor to reduce the exposure dose received by subjects and improve diagnostic performance. An X-ray imaging panel that reads and records a recorded electrostatic latent image with light or multiple electrodes is known. These are superior in that the resolution is higher than the indirect photographing method using a TV image pickup tube which is a well-known photographing method.

  The X-ray imaging panel described above generates charges corresponding to X-ray energy by irradiating the charge generation layer provided in the imaging panel with X-rays, and reads the generated charges as an electrical signal. The photoconductive layer functions as a charge generation layer. Conventionally, amorphous selenium has been used as the photoconductive layer. However, since amorphous selenium generally has a low X-ray absorption rate, the photoconductive layer must be formed thick (for example, 500 μm or more).

  However, when the film thickness is increased, the reading speed decreases, and since a high voltage is applied to the photoconductive layer at least after the start of reading after the latent image is formed, the dark current increases, and the dark current is increased. There is a problem in that the charge is added to the latent image charge and the contrast in the low-dose region is lowered. Further, since a high voltage is applied, the device is likely to be deteriorated, durability is lowered, and electric noise is likely to be generated. Furthermore, since the photoconductive layer is usually formed by vapor deposition, it takes a considerable amount of time to grow the photoconductive layer until the thickness becomes as described above, and its management is difficult. This eventually increases the manufacturing cost, leading to an increase in the cost of the X-ray imaging panel.

Because of these problems, materials for photoconductive layers other than selenium have been studied. For example, in Patent Documents 1 and 2, as a substance constituting the photoconductive layer, a composition formula Bi _x MO _y (where M is at least one of Ge, Si, and Ti, and x is 10 ≦ x ≦ 14). Wherein y represents the stoichiometric number of oxygen atoms by M and x.). According to this bismuth oxide composite oxide, it can be expected to improve the X-ray charge conversion efficiency.
JP-A-11-237478 JP 2000-249769

  By the way, in Patent Documents 1 and 2, as a method for forming this photoconductive layer, a sol or gel obtained by hydrolyzing bismuth and a metal alkoxide is sintered, dispersed and applied. It is described to do.

  However, the filling rate of the photoconductive material of the photoconductive layer that can be generally formed by coating is limited. In addition, since the binder is interposed between the photoconductive substance particles, the generated charge is difficult to flow, the efficiency of collecting the charge reaching the electrode is low, and the electric noise is increased, so that the graininess of the image is deteriorated. . In addition, the photoconductive layers described in Patent Documents 1 and 2 have low X-ray absorptivity because of a low filling rate. For this reason, attempts are being made to increase the film thickness. If the thickness is increased, the dark current increases and the charge due to the dark current is added to the latent image charge, and the problem of reducing the contrast in the low dose region cannot be solved.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a novel method for producing a photoconductive layer made of a bismuth oxide-based composite oxide.

In the method for producing a photoconductive layer constituting the radiation imaging panel of the present invention, a Bi ₁₂ MO ₂₀ precursor solution (where M is at least one of Ge, Si and Ti) is prepared by reacting a bismuth salt and a metal alkoxide under acidic conditions. is a species. hereinafter, the description is omitted.) which the Bi ₁₂ MO ₂₀ precursor solution was applied to a substrate, and sintering the Bi ₁₂ MO ₂₀ precursor solution coated on the support Bi ₁₂ MO _The photoconductive layer comprising a ₂₀ sintered film is produced.

The bismuth salt is preferably bismuth nitrate or bismuth acetate. More preferably, the Bi ₁₂ MO ₂₀ precursor liquid is obtained by concentrating or refluxing after the hydrolysis.

In the method for producing a photoconductive layer constituting the radiation imaging panel of the present invention, a Bi ₁₂ MO ₂₀ precursor liquid is obtained by reacting a bismuth salt and a metal alkoxide under acidic conditions, and this Bi ₁₂ MO ₂₀ precursor liquid is used as a support. Since the Bi ₁₂ MO ₂₀ precursor liquid applied to this support is fired to produce a photoconductive layer made of a Bi ₁₂ MO ₂₀ sintered film, the Bi ₁₂ MO of the photoconductive layer is formed as compared with the case where it is formed by coating. A filling factor of ₂₀ can be increased. In addition, since no binder is present between the photoconductive material grains, the generated charges can easily flow, the efficiency of collecting the charges reaching the electrodes is increased, and the electrical noise is reduced, so that the graininess of the image can be improved. It becomes possible.

In the method for producing a photoconductive layer constituting the radiation imaging panel of the present invention, a Bi ₁₂ MO ₂₀ precursor liquid is obtained by reacting a bismuth salt and a metal alkoxide under acidic conditions, and the obtained Bi ₁₂ MO ₂₀ precursor liquid is used. It was applied to a support, characterized in that to produce a photoconductive layer formed of Bi ₁₂ MO ₂₀ sintered film by firing Bi ₁₂ MO ₂₀ precursor solution was coated on a support.

The bismuth salt is preferably bismuth nitrate or bismuth acetate, and the metal alkoxide is an alkoxide of Ge, Si, Ti, more specifically, Ge (O—CH ₃ ) ₄ , Ge (O—C ₂ H ₅ ) _4. , Ge (O—iC ₃ H ₇ ) ₄ , Si (O—CH ₃ ) ₄ , Si (O—C ₂ H ₅ ) ₄ , Si (O—iC ₃ H ₇ ) ₄ , Ti (O—CH ₃ ) ₄ , Ti (O—C ₂ H ₅ ) ₄ , Ti (O—iC ₃ H ₇ ) _{4 and the} like can be preferably exemplified.

  As a method of reacting a bismuth salt and a metal alkoxide under acidic conditions, it can be carried out by a known method as appropriate. It is preferable to hydrolyze with an aqueous solution or the like.

After hydrolysis, a Bi ₁₂ MO ₂₀ precursor solution is obtained, but it is more preferable to perform concentration or reflux before applying it to the support. When the main calcination is performed without concentration or reflux, depending on the temperature condition of the main calcination, another phase such as Bi ₂ MO ₅ or Bi ₄ M ₃ O ₁₂ is generated in addition to the Bi ₁₂ MO ₂₀ phase. Because there is a case to do.

The obtained Bi ₁₂ MO ₂₀ precursor liquid is applied to a support, and the Bi ₁₂ MO ₂₀ precursor liquid applied to the support is baked to obtain a photoconductive layer composed of a Bi ₁₂ MO ₂₀ sintered film.

  In the radiation imaging panel, a direct conversion method in which radiation is directly converted into charges and stored, and radiation is converted into light once by a scintillator such as CsI, and the light is converted into charges by an a-Si photodiode and stored. Although there is an indirect conversion method, the photoconductive layer manufactured by the manufacturing method of the present invention can be used for the former direct conversion method. In addition to X-rays, γ rays, α rays, etc. can be used as radiation.

  In addition, the photoconductive layer manufactured by the manufacturing method of the present invention can be read by a radiation image detector using a semiconductor material that generates a charge when irradiated with light. Can be used for a method (hereinafter referred to as TFT method) in which the accumulated charge is read by turning on and off an electrical switch such as a thin film transistor (TFT) one pixel at a time.

  First, a radiation imaging panel used for the former optical reading method will be described as an example. FIG. 1 is a sectional view showing an embodiment of a radiation imaging panel having a photoconductive layer manufactured by the manufacturing method of the present invention.

  The radiation imaging panel 10 includes a first conductive layer 1 that is transparent to a recording radiation L1, which will be described later, and a recording radiation that exhibits conductivity when irradiated with the radiation L1 transmitted through the conductive layer 1. The conductive layer 2 and the charge charged on the conductive layer 1 (latent image polar charge; for example, negative charge) act as an insulator and have a charge opposite to the charge (transport polar charge; in the above example) Is positively charged) with respect to the charge transport layer 3 that acts as a substantially conductive material, the reading photoconductive layer 4 that exhibits conductivity when irradiated with the reading light L2 for reading described later, and the reading light L2. The second conductive layer 5 having transparency is laminated in this order.

  Here, as the conductive layers 1 and 5, for example, a transparent glass plate in which a conductive substance is uniformly applied (nesa film or the like) is suitable. As the charge transport layer 3, the larger the difference between the mobility of the negative charge charged in the conductive layer 1 and the mobility of the positive charge having the opposite polarity, the better, poly N-vinylcarbazole (PVK), N, N Organic compounds such as' -diphenyl-N, N'-bis (3-methylphenyl)-[1,1'-biphenyl] -4,4'-diamine (TPD) and discotic liquid crystals, or TPD polymers ( Polycarbonate, polystyrene, PVK) dispersion, semiconductor materials such as a-Se doped with 10 to 200 ppm of Cl are suitable. In particular, organic compounds (PVK, TPD, discotic liquid crystal, etc.) are preferable because they have light insensitivity, and since the dielectric constant is generally small, the capacitance of the charge transport layer 3 and the photoconductive layer 4 for reading is reduced, and thus reading is performed. The signal extraction efficiency can be increased.

  The reading photoconductive layer 4 includes a-Se, Se-Te, Se-As-Te, metal-free phthalocyanine, metal phthalocyanine, MgPc (Magnesium phtalocyanine), VoPc (phase II of Vanadyl phthalocyanine), CuPc (Cupper phtalocyanine), and the like. Among them, a photoconductive material mainly containing at least one of them is preferable.

For the recording radiation conductive layer 2, a photoconductive layer made of a Bi ₁₂ MO ₂₀ sintered film manufactured by the manufacturing method of the present invention is used. That is, the photoconductive layer produced by the production method of the present invention is a recording radiation conductive layer.

  Next, a system that uses light to read an electrostatic latent image will be briefly described. FIG. 2 is a schematic configuration diagram of a recording / reading system using the radiation imaging panel 10 (integrated electrostatic latent image recording device and electrostatic latent image reading device). This recording / reading system comprises a radiation imaging panel 10, a recording irradiation means 90, a power source 50, a current detection means 70, a reading exposure means 92, and connection means S1, S2. The panel 10, the power supply 50, the recording irradiation means 90, and the connection means S 1, and the electrostatic latent image reading device portion includes the radiation imaging panel 10, the current detection means 70, and the connection means S 2.

  The conductive layer 1 of the radiation imaging panel 10 is connected to the negative electrode of the power source 50 through the connection means S1, and is also connected to one end of the connection means S2. One end of the connection means S2 is connected to the current detection means 70, and the conductive layer 5 of the radiation imaging panel 10, the positive electrode of the power supply 50, and the other end of the connection means S2 are grounded. The current detection means 70 includes a detection amplifier 70a made of an operational amplifier and a feedback resistor 70b, and constitutes a so-called current-voltage conversion circuit.

  A subject 9 is disposed on the upper surface of the conductive layer 1, and the subject 9 has a portion 9a that is transparent to the radiation L1 and a blocking portion (light-shielding portion) 9b that is not transparent. The recording irradiation means 90 uniformly exposes the radiation L1 to the subject 9, and the reading exposure means 92 scans and exposes the reading light L2 such as infrared laser light, LED or EL in the direction of the arrow in FIG. Therefore, it is desirable that the reading light L2 has a beam shape converged to a small diameter.

  Hereinafter, an electrostatic latent image recording process in the recording / reading system having the above configuration will be described with reference to a charge model (FIG. 3). In FIG. 2, the connection means S2 is opened (not connected to either the ground or current detection means 70), the connection means S1 is turned on, and the DC voltage Ed from the power source 50 is applied between the conductive layer 1 and the conductive layer 5. Then, a negative charge is applied to the conductive layer 1 and a positive charge is applied to the conductive layer 5 from the power source 50 (see FIG. 3A). Thereby, a parallel electric field is formed between the conductive layers 1 and 5 in the radiation imaging panel 10.

  Next, the radiation L1 is uniformly irradiated toward the subject 9 from the recording irradiation means 90. The radiation L1 passes through the transmission part 9a of the subject 9, and further passes through the conductive layer 1. The radiation conductive layer 2 receives the transmitted radiation L1 and exhibits conductivity. This is understood by acting as a variable resistor that shows a variable resistance value according to the dose of radiation L1, and the resistance value is caused by the generation of a charge pair of electrons (negative charge) and holes (positive charge) by radiation L1. The resistance value is large if the dose of the radiation L1 transmitted through the subject 9 is small (see FIG. 3B). The negative charge (−) and the positive charge (+) generated by the radiation L1 are represented by enclosing − or + in circles in the drawing.

  The positive charge generated in the radiation conductive layer 2 moves at high speed in the radiation conductive layer 2 toward the conductive layer 1, and the negative charge is charged in the conductive layer 1 at the interface between the conductive layer 1 and the radiation conductive layer 2. And disappear due to charge recombination (see FIGS. 3C and 3D). On the other hand, the negative charges generated in the radiation conductive layer 2 move in the radiation conductive layer 2 toward the charge transfer layer 3. Since the charge transfer layer 3 acts as an insulator for charges having the same polarity as the charges charged in the conductive layer 1 (in this example, negative charges), the negative charges that have moved through the radiation conductive layer 2 are radiation. It stops at the interface between the conductive layer 2 and the charge transfer layer 3 and accumulates at this interface (see FIGS. 3C and 3D). The amount of charge accumulated is determined by the amount of negative charge generated in the radiation conductive layer 2, that is, the dose of radiation L1 transmitted through the subject 9.

  On the other hand, since the radiation L1 does not pass through the light shielding part 9b of the subject 9, no change occurs in the portion corresponding to the lower part of the light shielding part 9b of the radiation imaging panel 10 (see FIGS. 3B to 3D). In this way, by exposing the subject 9 to the radiation L1, charges corresponding to the subject image can be accumulated at the interface between the radiation conductive layer 2 and the charge transfer layer 3. The subject image based on the accumulated charges is called an electrostatic latent image.

  Next, an electrostatic latent image reading process will be described with reference to a charge model (FIG. 4). The connection means S1 is opened to stop the power supply, and S2 is temporarily connected to the ground side, and the conductive layers 1 and 5 of the radiation imaging panel 10 on which the electrostatic latent image is recorded are charged to the same potential to recharge the charge. After the arrangement (see FIG. 4A), the connection means S2 is connected to the current detection means 70 side.

  When the reading light L2 is scanned and exposed to the conductive layer 5 side of the radiation imaging panel 10 by the reading exposure means 92, the reading light L2 passes through the conductive layer 5, and the photoconductive layer 4 irradiated with the transmitted reading light L2 is Conductivity is exhibited according to scanning exposure. This is dependent on the fact that the radiation conductive layer 2 is irradiated with the radiation L1 to generate positive and negative charge pairs, and has a positive and negative charge pair upon irradiation with the reading light L2. (See FIG. 4B). As in the recording process, negative charges (−) and positive charges (+) generated by the reading light L2 are represented by enclosing − or + in circles in the drawing.

  Since the charge transport layer 3 acts as a conductor for positive charges, the positive charge generated in the photoconductive layer 4 rapidly moves in the charge transport layer 3 so as to be attracted to the accumulated charges, The accumulated charge and charge recombination disappear at the interface between the radiation conductive layer 2 and the charge transport layer 3 (see FIG. 4C). On the other hand, the negative charge generated in the photoconductive layer 4 disappears by recombining with the positive charge of the conductive layer 5 (see FIG. 4C). The photoconductive layer 4 is scanned and exposed with a sufficient amount of light by the reading light L2, and the accumulated charges accumulated at the interface between the radiation conductive layer 2 and the charge transport layer 3, that is, the electrostatic latent image are all recombined. Will be extinguished. Thus, the disappearance of the charges accumulated in the radiation imaging panel 10 means that the current I has flowed through the radiation imaging panel 10 due to the movement of charges, and this state is the radiation imaging panel 10. Can be expressed by an equivalent circuit as shown in FIG. 4D, in which the current amount is expressed by a current source whose amount depends on the accumulated charge amount.

  In this way, by detecting the current flowing out from the radiation imaging panel 10 while scanning and exposing the reading light L2, it is possible to sequentially read the accumulated charge amount of each scanning-exposed part (corresponding to the pixel). The electrostatic latent image can be read. The operation of the radiation detection unit is described in Japanese Patent Application Laid-Open No. 2000-105297.

  Next, the latter TFT type radiation imaging panel will be described. This radiation imaging panel has a structure in which a radiation detection unit 100 and an active matrix array substrate (hereinafter referred to as an AMA substrate) 200 are joined as shown in FIG. As shown in FIG. 6, the radiation detection unit 100 is roughly divided into a common electrode 103 for applying a bias voltage and light that generates carriers that are electron-hole pairs in response to the radiation to be detected in order from the radiation incident side. The conductive layer 104 and the detection electrode 107 for collecting carriers are stacked. The radiation detection unit support 102 may be provided on the upper layer of the common electrode.

  The photoconductive layer 104 is manufactured by the manufacturing method of the present invention. The common electrode 103 and the detection electrode 107 are made of a conductive material such as ITO (indium tin oxide), Au, or Pt, for example. Depending on the polarity of the bias voltage, a hole injection blocking layer and an electron injection blocking layer may be attached to the common electrode 103 and the detection electrode 107.

  The configuration of each part of the AMA substrate 200 will be briefly described. As shown in FIG. 7, the AMA substrate 200 is provided with a capacitor 210 as a charge storage capacitor and a TFT 220 as a switching element for each of the radiation detection portions 105 corresponding to pixels. In the support 102, the radiation detection units 105 corresponding to the pixels are two-dimensionally arranged in a matrix configuration of about 1000 to 3000 × 1000 to 3000 in accordance with the required pixels, and the AMA substrate 200 also has pixels. The same number of capacitors 210 and TFTs 220 are two-dimensionally arranged in the same matrix configuration. The electric charge generated in the photoconductive layer is accumulated in the capacitor 210 and becomes an electrostatic latent image corresponding to the optical reading method. In the TFT method of the present invention, an electrostatic latent image generated by radiation is held in a charge storage capacitor.

  Specific configurations of the capacitor 210 and the TFT 220 in the AMA substrate 200 are as shown in FIG. That is, the AMA substrate support 230 is an insulator, and the connection side electrode 210b of the capacitor 210 and the TFT 220 are formed on the ground electrode 210a of the capacitor 210 and the gate electrode 220a of the TFT 220 formed on the surface thereof via the insulating film 240. In addition to the source electrode 220b and the drain electrode 220c being stacked, the outermost surface side is covered with a protective insulating film 250. Further, the connection side electrode 210b and the source electrode 220b are connected to each other and are formed simultaneously. As the insulating film 240 constituting both the capacitor insulating film of the capacitor 210 and the gate insulating film of the TFT 220, for example, a plasma SiN film is used. The AMA substrate 200 is manufactured by using a thin film forming technique or a fine processing technique used for manufacturing a liquid crystal display substrate.

  Subsequently, the joining of the radiation detection unit 100 and the AMA substrate 200 will be described. With the detection electrode 107 and the connection side electrode 210b of the capacitor 210 aligned, both substrates 100 and 200 are made of anisotropic conductive film (ACF) containing conductive particles such as silver particles and having conductivity only in the thickness direction. The substrates 100 and 200 are mechanically combined by heating and pressurizing and bonding together, and at the same time, the detection electrode 107 and the connection side electrode 210b are electrically connected by the interposition conductor 140. .

  Further, the AMA substrate 200 is provided with a read drive circuit 260 and a gate drive circuit 270. As shown in FIG. 7, the read drive circuit 260 is connected to a read wiring (read address line) 280 in the vertical (Y) direction that connects the drain electrodes of the TFTs 220 having the same column, and the gate drive circuit 270 has a row. A horizontal (X) direction read line (gate address line) 290 connecting the gate electrodes of the same TFT 220 is connected. Although not shown, one preamplifier (charge-voltage converter) is connected to one readout wiring 280 in the readout drive circuit 260. As described above, the read driving circuit 260 and the gate driving circuit 270 are connected to the AMA substrate 200. However, an integrated circuit in which the read drive circuit 260 and the gate drive circuit 270 are integrally formed in the AMA substrate 200 is also used.

The radiation detection operation by the radiation imaging apparatus in which the radiation detector 100 and the AMA substrate 200 are joined and combined is described in, for example, Japanese Patent Application Laid-Open No. 11-287862.
Examples of the method for producing a photoconductive layer constituting the radiation imaging panel of the present invention are shown below.

(Example 1)
Bi (NO ₃ ) ₃ is dissolved in acetic acid at 40 ° C., Si (O—C ₂ H ₅ ) ₄ is added to 1/12 times the molar equivalent of Bi, and 50 vol% of acetic acid is added here for hydrolysis. Water was added. Subsequently, it recirculate | refluxed in 80 degreeC air | atmosphere for 1 hour. After refluxing, it was concentrated under vacuum conditions at 60 ° C. for 12 minutes. Acetic acid was added so that the concentration of Bi (NO ₃ ) ₃ was the same as that before concentration to obtain a Bi ₁₂ SiO ₂₀ precursor solution. Au sputtering was performed as a lower electrode on a high-purity alumina substrate (99.6%), and a Bi ₁₂ SiO ₂₀ precursor solution was spin-coated (1500 rpm, 20 s) thereon. This was dried at 80 ° C. for 10 minutes in the atmosphere, and further pre-baked for 5 minutes at 350 ° C. in the atmosphere, followed by main baking at 850 ° C. for 1 hour in the air to form a Bi ₁₂ SiO ₂₀ fired film. Finally, Au was sputtered to a thickness of 60 nm as an upper electrode on the formed Bi ₁₂ SiO ₂₀ fired film, and a radiation imaging panel provided with a photoconductive layer made of the Bi ₁₂ SiO ₂₀ fired film was completed.

(Example 2)
A Bi ₁₂ GeO ₂₀ fired film was prepared in the same manner as in Example 1 except that Ge (O—C ₂ H ₅ ) ₄ was used instead of Si (O—C ₂ H ₅ ) ₄ used in Example 1. The radiation imaging panel provided with the photoconductive layer was completed.

(Example 3)
From the Bi ₁₂ TiO ₂₀ fired film, the same procedure as in Example 1 was used except that Ti (O—C ₂ H ₅ ) ₄ was used instead of Si (O—C ₂ H ₅ ) ₄ used in Example 1. The radiation imaging panel provided with the photoconductive layer was completed.

(Comparative Example 1)
The ITO substrate is sputtered with Au as the lower electrode, and Bi ₁₂ SiO ₂₀ obtained by mixing Bi ₂ O ₃ powder and SiO ₂ powder on the ITO substrate and firing at 800 ° C. is 1/9 times the polyester resin (manufactured by Toyobo) By coating using BYRON 200), a Bi ₁₂ SiO ₂₀ film was formed, and this coating film was heated and dried in the atmosphere at 60 ° C. for 4 hours. On this Bi ₁₂ SiO ₂₀ film, Au was sputtered as an upper electrode to a thickness of 60 nm to complete a radiation imaging panel provided with a photoconductive layer made of a Bi ₁₂ SiO ₂₀ film.

(Measurement method and measurement results)
The radiation imaging panels of Examples 1 to 3 and Comparative Example 1 were irradiated with 10 mR of X-rays for 0.1 second under the condition of a voltage of 500 V, and the photocurrent on the pulse generated under the condition of applying the voltage was converted to a voltage by a current amplifier. Converted and measured with a digital oscilloscope. From the obtained current / time curve, integration was performed in the range of the X-ray irradiation time, and the amount of generated charge was measured. As a result, the photoconductive layer of the radiation imaging panel of Examples 1 to 3 was light of the radiation imaging panel of Comparative Example 1. Compared to the conductive layer, the value was 10 times higher in terms of film thickness of 200 μm.

As described above, in the method for producing a photoconductive layer constituting the radiation imaging panel of the present invention, a Bi ₁₂ MO ₂₀ precursor liquid is obtained by reacting a bismuth salt and a metal alkoxide under acidic conditions, and this Bi ₁₂ MO ₂₀ precursor is obtained. Since the body fluid is applied to the support and the Bi ₁₂ MO ₂₀ precursor solution applied to the support is baked to produce a photoconductive layer made of a Bi ₁₂ MO ₂₀ sintered film, the photoconductivity is higher than when formed by coating. It becomes possible to increase the packing ratio of Bi ₁₂ MO _{20 in} the layer. In addition, since no binder is present between the photoconductive material grains, the generated charges can easily flow, the efficiency of collecting the charges reaching the electrodes is increased, and the electrical noise is reduced, so that the graininess of the image can be improved. It becomes possible.

Sectional drawing which shows one Embodiment of the radiation imaging panel which has a photoconductive layer manufactured with the manufacturing method of this invention Schematic configuration diagram of a recording and reading system using a radiation imaging panel Diagram showing the electrostatic latent image recording process in a recording and reading system using a charge model Diagram showing the electrostatic latent image reading process in the recording and reading system using a charge model Schematic diagram showing the combined state of the radiation detector and the AMA substrate Electrical circuit diagram showing equivalent circuit of AMA substrate Schematic cross-sectional view showing the pixels of the radiation detector

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Conductive layer 2 Recording radiation conductive layer 3 Charge transport layer 4 Recording photoconductive layer 5 Conductive layer 10 Radiation imaging panel 70 Current detection means

Claims (3)

A method for producing a photoconductive layer constituting a radiation imaging panel for recording radiation image information as an electrostatic latent image, comprising reacting a bismuth salt and a metal alkoxide under acidic conditions to provide a Bi ₁₂ MO ₂₀ precursor solution (M is Ge, Si, at least one of Ti.) give, by the Bi ₁₂ MO ₂₀ precursor solution was applied to a substrate, firing the Bi ₁₂ MO ₂₀ precursor solution coated on the support Bi _A method for producing a photoconductive layer, comprising producing the photoconductive layer comprising a ₁₂ MO ₂₀ sintered film.   2. The method for producing a photoconductive layer according to claim 1, wherein the bismuth salt is bismuth nitrate or bismuth acetate. The method for producing a photoconductive layer according to claim 1, wherein the Bi ₁₂ MO ₂₀ precursor liquid is obtained by concentrating or refluxing after the hydrolysis.

Images