JP2008047749A - Radiograph detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent an image retention and also surely prevent electric charge injection from an electrode layer into a reading photoconductive layer in a radiograph detector including a linear electrode for prevention of generation of paired photoelectric charge. <P>SOLUTION: The electrode layer 5 consists of: a first linear electrode 5a for generation of paired photoelectric charge; and a second linear electrode 5b for prevention of the generation of paired photoelectric charge with the same thickness as that of the first electrode 5a. The electrodes are alternately arranged approximately in parallel. The layer 5 further includes an insulator 5c with the same thickness as that of the first electrode 5a and interposed between the first and second electrodes 5a and 5b. A flat layer having a flat surface includes a light-shielding film 8a having a light-shielding property against read light provided in the lamination direction on at least a part corresponding to the second electrode 5b. An electric charge injection preventive layer 7 is provided between the layers 5 and 4 for preventing electric charge from being injected from the electrode of the electrode layer 5 into the reading photoconductive layer 4. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a radiographic image detector that receives a radiation image carrying a radiographic image, records the radiographic image, and scans with a reading light to read out a signal corresponding to the radiographic image.

  2. Description of the Related Art Conventionally, in the medical field and the like, various radiological image detectors that generate a charge upon irradiation of radiation transmitted through a subject and record a radiation image related to the subject by accumulating the charge have been proposed and put into practical use.

  As the radiation image detector as described above, for example, as shown in FIG. 5, a recording light side electrode layer 21 that is transmissive to recording light, and a latent image charge is generated by receiving irradiation of recording light. The recording photoconductive layer 22, the charge transport layer 23 acting as an insulator for the latent image charge and acting as a conductor for the transport charge having the opposite polarity to the latent image charge, and the reading light A reading photoconductive layer 24 that exhibits conductivity upon irradiation, and a reading light side electrode layer 25 that is transparent to the reading light and includes a large number of linear electrodes 25a include a reading light side electrode layer 25. Are stacked on a support 29 that is transparent to the reading light in order, and a signal charge (latent potential) that carries image information in a power storage unit 26 formed at the interface between the recording photoconductive layer 22 and the charge transport layer 23. A radiation image detector 20 for accumulating image charge) is known. There. In the radiation image detector 20 shown in FIG. 5, the reading light conductive layer 24 and the reading light side electrode layer 25 are transparent to the reading light, and the linear electrodes of the reading light side electrode layer 25 are provided. A charge injection blocking layer (blocking layer having a blocking performance) 27 for blocking charge injection from the photoconductive layer 24 for reading from 25a is provided (see Patent Document 1).

  If the charge injection blocking layer 27 is not provided, a part of the charge charged on the linear electrode 25a of the reading light side electrode layer 25 is directly injected into the reading photoconductive layer 24, and this injection is performed. The charged charges move in the charge transport layer 23 and recombine with the accumulated latent image charges to disappear the latent image charges. The disappearance of the latent image charge due to the charge recombination is not caused by the irradiation of the reading light, and is a so-called noise component. Therefore, by laminating the charge injection blocking layer 27 as described above, injection of charges charged in the linear electrode 25a of the reading light side electrode layer 25 into the reading photoconductive layer 24 is blocked, and generation of noise is prevented. Can be prevented.

  Patent Document 2 discloses a first conductive layer that is transmissive to recording light, a recording photoconductive layer that generates charges when irradiated with radiation, and an insulator for latent image charges. A charge transport layer that acts as a conductor for transport charges having a polarity opposite to that of the latent image charge, a read photoconductive layer that generates charges when irradiated with read light, and transmits the read light A radiation image detector is proposed in which a second conductive layer in which photo-charge pair generating linear electrodes and photo-charge pair non-generating linear electrodes that shield reading light are alternately arranged in parallel is laminated in this order. ing.

According to the radiation image detector including the photocharge pair non-generating linear electrode as in Patent Document 2, at the time of reading, the reading light to the portion of the reading photoconductive layer corresponding to the photocharge non-generating linear electrode Can be prevented, and discharge between the power storage unit for accumulating the latent image charge and the photocharge pair non-generating linear electrode can be prevented. As a result, compared with the case where no photocharge pair generating linear electrode is provided, the discharge in the photoconductive layer for reading near the photocharge pair generating linear electrode is relatively increased, and the photocharge pair generating linear electrode is increased. Thus, the amount of signal charge that can be taken out from the radiation image detector can be relatively increased, and the reading efficiency can be improved.
JP 2001-264442 A JP 2003-31836 A

  If the charge injection blocking layer is thick, unnecessary charges remain in the charge injection blocking layer during the reading process. Since such residual charges are added to the latent image charge carrying image information at the next reading and detected as an image signal, an afterimage due to the residual charge appears in the radiation image based on the detected image signal. End up. Therefore, in order to prevent an afterimage, the charge injection blocking layer needs to be a predetermined thickness or less.

  However, when the thickness of the charge injection blocking layer is reduced, there is a surface step between the linear electrode 25a of the reading light side electrode layer 25 and the support 29, so that the edge portion of the linear electrode 25a as shown in FIG. Therefore, there is a possibility that a step break occurs in which the charge injection blocking layer 27 is not formed. When the step breakage occurs, charges are injected from this portion into the reading photoconductive layer 24. This dark current injection causes a problem that the blocking performance deteriorates and the S / N deteriorates.

  Furthermore, when the electrode of the reading light side electrode layer 25 is constituted by a linear electrode, the linear electrode may be relatively thick in order to reduce the longitudinal resistance (linear resistance). The thicker the electrode, the larger the surface step, and the easier the step breaks.

  Also, in the detector having the photocharge pair non-generating linear electrode as described in Patent Document 2 described above, dark current noise is generated from the photocharge pair non-generating linear electrode, and this dark current noise is stored in the power storage unit. Therefore, it is necessary to provide a charge injection blocking layer on the photo-electric charge pair non-generating linear electrode. Even when the charge-injection blocking layer is provided on the photo-charge pair non-generating linear electrode, there is a risk of step breakage and deterioration of blocking performance due to the surface step as in the case shown in FIG. . In this case, in particular, since the width of the photocharge pair generating linear electrode and the photocharge pair non-generating linear electrode becomes narrower and a fine pitch, the deterioration becomes more remarkable. In addition, since it is necessary to provide the light-shielding property to the reading light in the non-generating photo-charge pair linear electrode, it may have a certain thickness in its manufacture. When the thickness is thicker than that of the photocharge pair generating linear electrode, the deterioration of the blocking performance due to the step becomes more remarkable.

  In view of the above circumstances, the present invention prevents afterimages and reliably prevents charge injection from the electrode layer to the photoconductive layer for reading in a radiation image detector provided with a linear electrode for generating no photocharge pairs. An object of the present invention is to provide a radiological image detector capable of performing the above.

  The radiological image detector of the present invention includes a flat layer having a flat surface, a first linear electrode for generating a photocharge pair, a first linear electrode on a support that is transparent to reading light, and the first linear electrode. An electrode layer in which photocharge pairs having the same thickness as that of the linear electrode and second linear electrodes for non-generation are alternately arranged substantially in parallel, and a photoconductive layer that generates charges by irradiation of the reading light In the radiation image detector formed by laminating in order, the flat layer includes a light-shielding film having a light-shielding property with respect to the reading light disposed at least in a portion corresponding to the second linear electrode in the laminating direction. The electrode layer further includes an insulator having the same thickness as the first linear electrode and interposed between the first linear electrode and the second linear electrode. , Between the first and second linear electrodes between the electrode layer and the photoconductive layer. Wherein the charge injection blocking layer for blocking the injection of charges into the conductive layer is provided.

  Here, “the same thickness as the first linear electrode” means that the thickness is within an average value ± 10% of the thickness of the first linear electrode.

  Here, the “first linear electrode for generating a photocharge pair” is an electrode for generating a charge pair in the photoconductive layer, and the “second linear electrode for generating no photocharge pair” is used. "Is an electrode that does not generate charge pairs in the photoconductive layer.

  Here, the “light-shielding film having a light-shielding property with respect to the reading light” is not limited to a film that completely blocks the reading light and does not generate a charge pair at all, and has some transparency to the reading light. However, a charge pair generated by the charge is not included in the problem.

  Note that “at least the corresponding part of the second linear electrode” means the entire corresponding area of the second linear electrode. Further, the light shielding film is not disposed in the entire corresponding region of the first linear electrode in the stacking direction.

  Further, the “reading light” is not limited as long as it can move the electric charge in the electrostatic recording body and can electrically read the electrostatic latent image. Specifically, it is light, radiation, or the like. .

  According to the radiation image detector of the present invention, an insulator having the same thickness as the first linear electrode and the second linear electrode is interposed between the first linear electrode and the second linear electrode. Therefore, the electrode layer can be flattened to eliminate the surface step. Therefore, even if a charge injection blocking layer is provided between the electrode layer and the photoconductive layer and the thickness thereof is reduced, there is no risk of step breakage and charge injection from the electrode layer to the photoconductive layer is reliably prevented. Can do. In addition, since the thickness of the charge injection blocking layer can be reduced, residual charges are not generated and an afterimage can be prevented.

  In general, the first linear electrode for generating photocharge pairs is transmissive to reading light, and the second linear electrode for non-generating photocharge pairs is light-shielding to reading light. Conventionally, the first linear electrode and the second linear electrode are formed of different materials, or when both are formed of the same material, only the second linear electrode is conventionally used. It was necessary to form a light shielding film. On the other hand, in the radiological image detector of the present invention, since the light shielding film is provided on the corresponding part of the second linear electrode of the flat layer to ensure the light shielding property regarding the second linear electrode, It is possible to form the two linear electrodes with a material having transparency to the reading light. This makes it possible to produce the first linear electrode and the second linear electrode in the same process by using the same material for the first linear electrode and the second linear electrode. The process can be simplified. Further, in the case where the light shielding film is formed only on the conventional second linear electrode, the thickness of the first linear electrode and the second linear electrode is different, so that the electrode layer can be easily flattened. However, according to the radiological image detector of the present invention, since it is not necessary to form a light shielding film on the second linear electrode, the first linear electrode and the second linear electrode are made the same. The thickness can be increased, and the flatness of the electrode layer can be more easily ensured.

  Hereinafter, an embodiment of the radiation image detector of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of the radiation image detector, and FIG. 2 is a cross-sectional view of the radiation image detector shown in FIG.

  As shown in FIGS. 1 and 2, the radiation image detector 10 receives the radiation of the first electrode layer 1 that transmits the radiation carrying the radiation image and the radiation that has passed through the first electrode layer 1. The recording photoconductive layer 2 that generates charge, and acts as an insulator for the latent image charge out of the charges generated in the recording photoconductive layer 2, and for the transport polarity charge having the opposite polarity to the latent image charge The charge transport layer 3 acting as a conductor, the read photoconductive layer 4 that generates charges when irradiated with the read light, and the charge injection from the second electrode layer 5 to the read photoconductive layer 4 On the other hand, a charge injection blocking layer 7 having blocking performance, a second electrode layer 5 that transmits reading light, and a flat layer 8 are laminated in this order. Between the recording photoconductive layer 2 and the charge transport layer 3, a power storage unit 6 for accumulating charges generated in the recording photoconductive layer 2 is formed. Each layer is formed in order from the flat layer 8 on a support 9 such as a glass substrate that transmits the reading light, but the support 9 is omitted in FIG.

  The embodiment described below is formed at the interface between the recording photoconductive layer 2 and the charge transport layer 3 by charging the first electrode layer 1 with a negative charge and the second electrode layer 5 with a positive charge. The negative charge as the latent image charge is accumulated in the power storage unit 6, and the charge transport layer 3 has the positive charge mobility as the transport polarity charge having the opposite polarity to the negative charge mobility as the latent image charge. However, each of these may be a charge having a reverse polarity, and when the polarity is reversed in this way, It is only necessary to make a slight change such as changing the charge transport layer functioning as a hole transport layer to a charge transport layer functioning as an electron transport layer.

The first electrode layer 1 may be any material that transmits radiation. For example, Nesa film (SnO ₂ ), ITO (Indium Tin Oxide), IDIXO (Idemitu Indium X--) which is an amorphous light-transmitting oxide film. metal Oxide (Idemitsu Kosan Co., Ltd.) can be used with a thickness of 50 to 200 nm, and Al or Au with a thickness of 100 nm can also be used.

  The second electrode layer 5 includes a plurality of first linear electrodes 5a for generating photocharge pairs, a plurality of second linear electrodes 5b for non-generating photocharge pairs, and a first linear electrode 5a. And an insulator 5c interposed between the second linear electrode 5b. The first linear electrodes 5a and the second linear electrodes 5b have the same thickness T, and are alternately arranged substantially in parallel on the surface of the flat layer 8 at a predetermined interval. The insulator 5c also has the same thickness T as the first linear electrode 5a and the second linear electrode 5b, and is provided so as to flatten the electrode layer 5 by filling the space therebetween.

  The first linear electrode 5a and the second linear electrode 5b are made of a material having conductivity with respect to reading light and having conductivity. Any material may be used as long as it is as described above. For example, ITO or IDIXO can be used with a thickness of 0.1 to 1 μm. Alternatively, a metal such as Al or Cr may be used to form a thickness that allows the reading light to pass (for example, about 10 nm).

The insulator 5c is made of a material having transparency while being transmissive to the reading light. Any material may be used as long as it is as described above. For example, SiO ₂ or the like can be used.

  The recording photoconductive layer 2 only needs to generate a charge when irradiated with radiation, and is excellent in that it has a relatively high quantum efficiency with respect to radiation and a high dark resistance. What has Se (amorphous selenium) as a main component can be used. A thickness of 100 to 1000 μm is appropriate.

As the charge transport layer 3, for example, the larger the difference between the mobility of charges charged in the first electrode layer 1 at the time of recording a radiographic image and the mobility of charges having the opposite polarity, the better (for example, 10 ^2). Or more, preferably 10 ³ or more) poly N-vinylcarbazole (PVK), N, N′-diphenyl-N, N′-bis (3-methylphenyl)-[1,1′-biphenyl] -4,4 ′ An organic compound such as diamine (TPD) or discotic liquid crystal, a TPD polymer (polycarbonate, polystyrene, PVK) dispersion, or a semiconductor material such as a-Se doped with 10 to 200 ppm of Cl is suitable.

  The reading photoconductive layer 4 may be any material that exhibits conductivity when irradiated with reading light. For example, a-Se, Se-Te, Se-As-Te, metal-free phthalocyanine, metal phthalocyanine, A photoconductive substance mainly containing at least one of MgPc (Magnesium phthalocyanine), VoPc (phase II of Vanadyl phthalocyanine), CuPc (Cupper phthalocyanine), and the like is preferable. A thickness of about 0.1 to 10 μm is appropriate.

  The charge injection blocking layer 7 has a blocking performance that blocks charge injection from the first linear electrode 5a and the second linear electrode 5b of the second electrode layer 5 into the reading photoconductive layer 4 (barrier). Have a potential). The charge injection blocking layer 7 is formed of a material that is transmissive to reading light, and an organic thin film can be used, for example.

  When the charge injection blocking layer 7 is not provided, a part of the charge (positive charge in this example) charged to the linear electrode 5a and the second linear electrode 5b of the second electrode layer 5 is used. May be directly injected into the reading photoconductive layer 4, and the positive charge directly injected into the reading photoconductive layer 4 moves in the charge transport layer 3 to recombine with the accumulated latent image charge. As a result, the latent image charge disappears. The disappearance of the latent image charge due to the charge recombination is not caused by the irradiation of the reading light, and is a so-called noise component. On the other hand, in the case where the charge injection blocking layer 7 is provided as in the radiation image detector 10 of the present embodiment, the positive photocharge charged in the second electrode layer 5 is a barrier photoelectric potential, so that the photoconductive layer for reading is used. No noise is generated by direct injection of positive charges.

  Note that the charge injection blocking layer 7 may function as a suppression layer that suppresses interface crystallization. As is well known, an amorphous selenium film undergoes interfacial crystallization at the interface with another metal during the deposition process during film formation. Since the radiation image detector 10 also forms the flat layer 8 on the support 9 and forms the reading photoconductive layer 4 after forming the second electrode layer 5, the reading photoconductive layer 4. Is formed to include the electrode material and a-Se in the vapor deposition process of the read photoconductive layer 4 and subsequent vapor deposition of the charge transport layer 3, the recording photoconductive layer 2, and the like. There is a problem that the S / N is lowered because interface crystallization proceeds at the interface and charge injection from the electrode increases. When a transparent oxide film, particularly ITO, is used as the electrode material, interface crystallization at the interface between the electrode material and a-Se proceeds remarkably, and the S / N reduction becomes significant. Therefore, if the charge injection blocking layer 7 of the radiation image detector 10 is formed of an organic thin film, the charge injection blocking layer 7 can function as a suppression layer that suppresses interface crystallization of a-Se, Direct contact between the electrode material of the second electrode layer 5 and a-Se of the reading photoconductive layer 4 can be prevented, and an effect of preventing chemical change of Se at the interface and preventing interface crystallization is obtained. The problem of S / N reduction can be solved.

  Further, the charge injection blocking layer 7 is made of an elastic material, and the charge injection blocking layer 7 functions as a buffer layer that relieves thermal stress between the support 9 and the reading photoconductive layer 4. You may make it make it. Furthermore, the charge injection blocking layer 7 may function as a layer that strengthens the adhesion between the read photoconductive layer 4 and the second electrode layer 5.

  Here, in order for the charge injection blocking layer 7 to function as a buffer layer that relieves thermal stress, it is preferable to use, for example, a layer of an organic thin film rich in elasticity. Examples of the organic thin film include polyamides and polyimides shown in US Pat. No. 4,535,468, polyesters, polyvinyl butyral, polyvinyl pyrrolidone, polyurethane, polymethyl methacrylate, polycarbonate, and the like. A thin film of an insulating organic polymer that is transparent to reading light (for example, blue light) and has good hole blocking performance can be used. It is also possible to use a thin layer of a mixed film composed of an organic binder and a low molecular weight organic material such as nigrosine at a weight ratio of about 0.3% to 3%.

  The film thickness of the organic thin film constituting the charge injection blocking layer 7 is preferably about 0.05 to 5 μm, but is preferably in the range of 0.1 to 5 μm from the viewpoint of thermal stress buffering, but good blocking performance without an afterimage. Therefore, a range of 0.05 to 0.5 μm is preferable, and a range of 0.1 to 0.5 μm is preferable in terms of a balance between the two.

The flat layer 8 includes a light shielding film 8a disposed in a corresponding portion of the second linear electrode 5b in the stacking direction, and an overcoat 8b that fills the light shielding film 8a and forms a flat surface. The light-shielding film 8a needs to have a light-shielding property with respect to the reading light. However, the light-shielding film 8a does not necessarily have an insulating property, and the specific resistance of the light-shielding film 8a is 2 × 10 ⁻⁶ Ω · cm or more (more preferably 1 × 10 ¹⁵ Ω · cm or less) can be used. For example, Al, Mo, Cr, or the like can be used for a metal material, and MoS ₂ , WSi ₂ , TiN, or the like can be used for an organic material. It is more preferable to use a light shielding film 8a having a specific resistance of 1 Ω · cm or more.

  The overcoat 8b is transmissive to the reading light, and for example, an acrylic resin can be used, and the thickness is desirably about 1 μm or less. When a conductive member such as a metal material is used as the member of the light shielding film 8a, the overcoat 8b is an insulator to avoid direct contact between the light shielding film 8a and the second linear electrode 5b.

  Since the light shielding film 8a can block the incidence of the reading light on the second linear electrode 5b, a charge pair for signal extraction is provided in the reading photoconductive layer 16 corresponding to the second linear electrode 5b. It can be prevented from being generated. Further, the flatness of the surface on which the second electrode layer 5 is provided (the surface on the flat layer 8 side of the second electrode layer 5) can be ensured by the overcoat 8b having a flat surface. 5 can ensure the flatness of the surface on the charge injection blocking layer 7 side more suitably.

  Further, by providing the light shielding film 8a as described above on the flat layer 8, it is not necessary to give the second linear electrode 5b itself a light shielding property, and the first linear electrode 5a and the second linear electrode are eliminated. 5b can be formed of the same material that transmits the reading light, and the first linear electrode 5a and the second linear electrode 5b can be manufactured in the same process.

The width W _s in the in-plane direction (horizontal direction in FIG. 2) of the light shielding film 8a is such that the center positions of the light shielding film 8a and the second linear electrode 5b coincide with each other in the stacking direction, and the first linear electrode 5a. width, the width of the second linear electrodes 5b, when the width of the insulator 5c is to be _{W a, W b, W c, respectively, W b ≦ W s ≦ (} W b + 2 × W c) satisfies It is desirable to do so. This condition is, the light shielding film 8a completely covers at least the second linear electrodes 5b, and secured by at least a width W _a portion of the first linear electrodes 5a as a transparent portion of the reading light, a first This indicates that the portion corresponding to the linear electrode 5a is not covered with the light shielding film 8a. However, only the width W _b component of the second linear electrodes 5b is insufficient shielding, but also transparent portion of the reading light is only the width W _a portion of the first linear electrodes 5a first linear electrodes Since there is a possibility that the reading light reaching 5a may become insufficient, it is preferable to satisfy (W _b + W _c / 2) ≦ Ws ≦ (W _b + W _c ).

  The support 9 may be transparent to the reading light, and for example, a glass substrate or an organic polymer material can be used. More preferably, the support 9 uses a material whose coefficient of thermal expansion is relatively close to that of the material of the flat layer 8, in this case during shipping in special circumstances, for example in cold climate conditions. In such a case, even when subjected to a large temperature cycle, thermal stress occurs at the interface between the support 9 and the flat layer 8, and both of them are physically separated, the flat layer 8 is broken, or the support 9 is cracked. The problem of destruction due to differential expansion does not occur. Note that the organic polymer material has an advantage that it is more resistant to impact than the glass substrate.

  Below, an example of the manufacturing process of this radiographic image detector 10 is demonstrated, referring FIG.

  First, a large number of linear light shielding films 8a are formed on a support 9 made of a glass substrate. The manufacturing process uses a general photolithography method and will be described below. A Cr film is formed on the upper surface of the support 9 by vapor deposition with a thickness of approximately 0.1 μm. Then, a color resist is applied to the entire upper surface of the Cr film, and ultraviolet light is exposed to a position corresponding to the second linear electrode 5b using a mask corresponding to the shape of the light-shielding film 8a to develop and wash (rinse) ) To form a resist pattern corresponding to the shape of the light shielding film 8a on the upper surface of the Cr film. Then, the light shielding film 8a is formed on the support 9 by etching the Cr film and removing the resist (FIG. 3 (1)). In FIG. 3, the Cr film is not shown.

  Next, an overcoat 8b is formed of an acrylic resin so as to embed the light shielding film 8a, and the surface is flattened by polishing or the like to form a flat layer 8 (FIG. 3 (2)).

  A transparent conductive film (ITO (Indium Tin Oxide)) 11 which is a material of the first linear electrode 5a and the second linear electrode 5b is uniformly formed on the entire upper surface of the support 9 on which the flat layer 8 is formed. (FIG. 3 (3)). Examples of the method for forming the transparent conductive film 11 include a vacuum deposition method and a dipping method. Then, using the photolithography method, a pattern corresponding to the shape of the first linear electrode 5a and the second linear electrode 5b is formed in the same manner as described above, etching is performed, and the first linear electrode 5a is formed. And the 2nd linear electrode 5b is formed (FIG. 1 (4)).

Next, the transparent insulating film (the first linear electrode 5a and the second linear electrode 5b are buried in the entire surface of the support 9 on which the first linear electrode 5a and the second linear electrode 5b are formed. SiO ₂ ) 12 is formed (FIG. 3 (5)). Examples of the method for forming the transparent insulating film 12 include sputtering, vacuum evaporation, and dipping. And the transparent insulating film 12 is grind | polished so that it may become the same thickness as the 1st linear electrode 5a and the 2nd linear electrode 5b, and the insulator 5c is formed (FIG. 3 (6)).

  As described above, the charge injection blocking layer 7 is formed on the second electrode layer 5 flattened by the first linear electrode 5a, the second linear electrode 5b, and the insulator 5c having the same thickness. The material to be formed is formed by coating or the like so as to have a predetermined thickness (FIG. 3 (7)). In the present embodiment, since the second electrode layer 5 is flattened, the application direction does not matter and can be easily applied using a method such as spin coating. As other film formation methods for the charge injection blocking layer 7, a dipping method, a spraying method (Spraying), a bar coating method, a screen coating method and the like can be used.

  Next, the operation of the radiation image detector 10 will be described.

  First, as shown in FIG. 4A, in a state where a negative voltage is applied to the first electrode layer 1 of the radiation image detector 10 by the high voltage source 15, radiation is irradiated from the radiation source toward the subject, and the subject The radiation carrying the radiation image of the subject through the radiation is irradiated from the first electrode layer 1 side of the radiation image detector 10.

  The radiation applied to the radiation image detector 10 passes through the first electrode layer 1 and is applied to the recording photoconductive layer 2. Then, a charge pair is generated in the recording photoconductive layer 2 by the irradiation of the radiation, and the positive charge is combined with the negative charge charged in the first electrode layer 1 and disappears, and the negative charge is a latent image. A radiographic image is recorded by being accumulated in the power storage unit 6 formed at the interface between the recording photoconductive layer 2 and the charge transport layer 3 as charges (see FIG. 4B).

  Then, as shown in FIG. 4C, in the state where the first electrode layer 1 is grounded, the reading light is irradiated from the flat layer 8 side, and the reading light is applied to the overcoat 8b and the second layer 8 of the flat layer 8. The reading photoconductive layer 4 is irradiated through the first linear electrode 5 a of the electrode layer 2. The positive charge generated in the reading photoconductive layer 4 by the irradiation of the reading light is combined with the latent image charge in the power storage unit 6, and the negative charge is charged to the first linear electrode 5 a of the second electrode layer 5. Combined with the positive charge.

  Then, a current flows through the charge amplifier 16 due to the combination of the negative charge and the positive charge as described above, the current is integrated and detected as an image signal, and the image signal corresponding to the radiation image is read.

  According to the radiation image detector 10 of the present embodiment described above, since the charge injection blocking layer 7 is provided between the planarized second electrode layer 5 and the reading photoconductive layer 4, the second Charge injection from the electrode layer 2 to the reading photoconductive layer 4 can be reliably prevented, and S / N deterioration can be prevented. Further, since the thickness of the charge injection blocking layer 7 can be reduced, no residual charge is generated in the charge injection blocking layer 7 and the occurrence of afterimage can be prevented.

  Further, in the radiation image detector 10 of the present embodiment, by providing the charge injection blocking layer 7 and the insulator 5c, the edge portions of the first linear electrode 5a and the second linear electrode 5b where the electric field concentrates are formed. Contact with the photoconductive layer can be avoided, and after-images caused by offset noise and point defects caused by dark current noise can be suppressed. Furthermore, by providing the second electrode layer 5 with the low dielectric constant insulator 5c, the capacitance of the radiation image detector 10 itself is reduced, and electrical noise when a voltage is applied to the radiation image detector 10 is obtained. Can be reduced.

  In the above-described embodiment, the present invention is applied to a so-called direct conversion type radiation oblique line image detector that records radiation images by receiving radiation irradiation and directly converting the radiation into electric charges. However, the present invention is not limited to this, and for example, the present invention is applied to a so-called indirect conversion type radiation image detector that records radiation images by once converting radiation into visible light and converting the visible light into electric charges. It may be.

  Further, the layer configuration of the radiation image detector in the radiation image detector of the present invention is not limited to the layer configuration as in the above embodiment, and other layers may be added.

Schematic configuration diagram of an embodiment of a radiation image detector of the present invention AA line sectional view of the radiation image detector shown in FIG. The figure for demonstrating an example of the manufacturing process of the radiographic image detector shown in FIG. The figure for demonstrating the effect | action of recording of the radiographic image to the radiographic image detector shown in FIG. The figure for demonstrating the effect | action of recording of the radiographic image to the radiographic image detector shown in FIG. The figure for demonstrating the effect | action of recording of the radiographic image to the radiographic image detector shown in FIG. The figure which shows the structure of the conventional radiographic image detector. The figure for demonstrating the step gap of the charge injection blocking layer in the conventional radiation image detector

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st electrode layer 2 Recording photoconductive layer 3 Charge transport layer 4 Reading photoconductive layer 5 2nd electrode layer 5a 1st linear electrode 5b 2nd linear electrode 5c Insulator 6 Power storage part 7 Charge Injection blocking layer 8 Flat layer 8a Light-shielding film 8b Overcoat 10 Radiation image detector 11 Transparent conductive film 12 Transparent insulating film 15 High voltage source 16 Charge amplifier

Claims (1)

On a support that is transparent to the reading light,
A flat layer having a flat surface;
Electrode layer in which first linear electrodes for generating photocharge pairs and second linear electrodes for non-generating photocharge pairs having the same thickness as the first linear electrodes are alternately arranged in parallel. When,
In the radiation image detector formed by laminating the photoconductive layer that generates charges by irradiation of the reading light in this order,
The flat layer includes a light-shielding film having a light-shielding property with respect to the reading light disposed at least in a corresponding portion of the second linear electrode in the stacking direction;
The electrode layer further includes an insulator interposed between the first linear electrode and the second linear electrode with the same thickness as the first linear electrode;
A charge injection blocking layer for blocking charge injection from the first and second linear electrodes to the photoconductive layer is provided between the electrode layer and the photoconductive layer. Radiation image detector.

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