JP2014182002A - Radiographic image detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radiographic image detector that can be manufactured at low cost, has excellent impact resistance and high resolution, and can prevent decrease in its sensitivity.SOLUTION: An X-ray image detector 10 comprises a photoelectric conversion panel 21, a phosphor layer 20, and a resin layer 27. The photoelectric conversion panel 21 has an imaging surface on which pixels 41 each comprising a photodiode (PD) 43 for performing photoelectric conversion are aligned in a two-dimensional matrix. The phosphor layer 20 comprises a partition 23 having openings 23a each formed at a position corresponding to each PD 43, and a phosphor 24 filled in each opening 23a for converting X-rays into visible light. The cross-sectional area of the opening 23a in a direction parallel to the imaging surface is larger on the photoelectric conversion panel 21 side than on the side opposite to the photoelectric conversion panel 21 side. The phosphor 24 is filled in each opening 23a with a void remaining on the photoelectric conversion panel 21 side. The resin layer 27 is formed in the void.

Description

  The present invention relates to an indirect conversion radiation image detection apparatus.

  In the medical field and the like, a radiographic imaging system for observing the inside of a body is widespread. This radiographic imaging system detects a radiation source that emits radiation, such as X-rays, from a radiation source toward a subject, detects radiation that has passed through the subject, converts it into a charge, converts the charge into a voltage, And a radiological image detection device for generating image data representing the radiographic image of the above.

  The radiation image detection apparatus includes a direct conversion system that directly converts radiation into electric charges and an indirect conversion system that converts radiation once into visible light and converts the visible light into electric charge. The indirect conversion type radiological image detection apparatus includes a phosphor layer (scintillator) that converts radiation into visible light, and a photoelectric conversion panel that converts visible light generated by the phosphor layer into electric charge. In the photoelectric conversion panel, a plurality of pixels including photodiodes are arranged in a two-dimensional matrix, and a phosphor layer is stacked thereon.

The phosphor layer has a granular type having a particulate phosphor material (granular crystal) such as GOS (Gd ₂ O ₂ S: Tb) and a columnar phosphor material (columnar crystal) such as CsI: Tl. A columnar type is known.

  Since the granular type phosphor layer is formed by dispersing phosphor particles such as GOS in a binder (binder) such as a resin, there is an advantage that it has flexibility and excellent impact resistance. In particular, since the phosphor layer having GOS has a larger atomic number than Cs of heavy metal atoms contained in CsI, Gd of heavy metal atoms contained in GOS has a high radiation absorption rate in addition to impact resistance. However, in the granular type phosphor layer, visible light is isotropically radiated from the phosphor particles and has no light guide effect, so that the resolution of the image is low. In order to increase the conversion efficiency of radiation, the thickness of the phosphor layer may be increased. However, the larger the thickness, the greater the diffusion of visible light until it reaches the photoelectric conversion panel, resulting in a lower resolution. .

  On the other hand, the columnar type phosphor layer is a columnar crystal obtained by crystal growth of a phosphor material on a substrate. Since each columnar crystal has a light guide effect, the resolution of the image is high. However, in the columnar type phosphor layer, when trying to increase the film thickness, some columnar crystals are likely to grow abnormally and produce protrusions, and adjacent columnar crystals are likely to be fused together. There is a limit to film formation. In addition, the columnar type phosphor layer has a columnar crystal and has low impact resistance. Furthermore, the columnar type phosphor layer is expensive in material and increases in manufacturing cost.

  In view of this, it has been proposed that a radiation image detection apparatus having a granular type phosphor layer is provided with a partition that separates the phosphor layer in correspondence with each photodiode (see, for example, Patent Documents 1 to 3). The partition wall has an opening corresponding to each photodiode. Visible light generated by the phosphor in each opening is prevented from diffusing by the partition walls and efficiently guided to the corresponding photodiode, so that the resolution is improved. The granular type phosphor layer having such partition walls is excellent in manufacturing cost, impact resistance, and resolution.

  In the radiological image detection apparatus described in Patent Document 1, the cross-sectional area (aperture ratio) of the opening of the partition wall is constant in the thickness direction of the phosphor layer. When a partition wall is provided in the phosphor layer, the amount of light emitted from the phosphor layer is reduced by that amount. Therefore, in the radiation image detection devices described in Patent Documents 2 and 3, the aperture ratio on the photoelectric conversion panel side of the partition wall is By making it larger than the aperture ratio on the side opposite to the photoelectric conversion panel, the light emission amount of the phosphor layer on the photoelectric conversion panel side is increased.

JP 2002-055165 A JP 2011-232197 A Japanese Patent Laid-Open No. 9-61536

  However, as described in Patent Documents 2 and 3, when the aperture ratio of the partition wall on the photoelectric conversion panel side is increased, the width of the partition wall on the photoelectric conversion panel side is reduced by that amount and is easily damaged. Further, since the height of the partition wall is likely to vary, as described in Patent Document 2, when the phosphor layer is formed by filling the opening of the partition wall with the phosphor, The flatness of the surface on the photoelectric conversion panel side is low, unevenness is generated, and an air layer may be formed between the photoelectric conversion panel and the phosphor layer.

  When an air layer is interposed between the photoelectric conversion panel and the phosphor layer, a refractive index difference between the phosphor and the air layer is generated, and the phosphor has a refractive index larger than the refractive index of the air layer. Visible light going from the light to the photoelectric conversion panel is easily reflected at the interface between the phosphor and the air layer, and the incident efficiency of visible light to the photodiode is reduced (the sensitivity of the radiation image detection device is reduced). Arise.

  An object of the present invention is to provide a radiological image detection apparatus that is excellent in manufacturing cost, impact resistance, and resolution, and that can prevent a decrease in sensitivity.

  In order to solve the above problems, a radiological image detection apparatus of the present invention includes a photoelectric conversion panel having an imaging surface in which pixels including photodiodes that perform photoelectric conversion are two-dimensionally arranged, a partition wall, and a phosphor. Is arranged corresponding to each photodiode, and the cross-sectional area in the direction parallel to the imaging surface has a larger opening on the photoelectric conversion panel side than the side opposite to the photoelectric conversion panel, and the phosphor is Each of the openings includes a phosphor layer that is filled with leaving a gap on the photoelectric conversion panel side and converts radiation into visible light, and a resin layer formed in the gap.

  It is preferable that the photoelectric conversion panel and the phosphor layer are arranged in the order of the photoelectric conversion panel and the phosphor layer from the side on which the radiation is incident.

  In the phosphor layer, the surface on which the resin layer is formed is bonded to the photoelectric conversion panel via the adhesive layer, or the surface on which the resin layer is formed is in direct contact with the photoelectric conversion panel. preferable.

  It is preferable that the cross-sectional area of each opening gradually decreases in a direction away from the photoelectric conversion panel.

  A light reflecting layer that reflects visible light is preferably formed on the surface of the phosphor layer opposite to the photoelectric conversion panel. In this case, the phosphor layer is preferably formed on the phosphor support substrate via a light reflection layer.

  The phosphor preferably includes a binder and phosphor particles dispersed in the binder. The barrier ribs preferably have a refractive index lower than that of the phosphor.

  It is preferable that the aperture ratio of the partition wall on the photoelectric conversion panel side is 85% or more. In this case, the thickness of the phosphor layer is preferably 400 μm or more.

  According to the radiation image detection apparatus of the present invention, the partition wall has an opening having a larger cross-sectional area on the photoelectric conversion panel side than on the side opposite to the photoelectric conversion panel, and the phosphor is photoelectrically converted in each opening. Since the panel side is filled with a gap, and a resin layer is formed in the gap, an air layer is not interposed between the photoelectric conversion panel and the phosphor, and a reduction in sensitivity can be prevented.

It is a partially broken perspective view of an X-ray image detection apparatus. It is sectional drawing of an X-ray image detection apparatus. It is a top view of a partition and a photodiode. It is sectional drawing of FPD which follows the IV-IV line of FIG. It is a circuit diagram which shows the structure of a photoelectric conversion panel. It is FIG. (1) which shows the manufacturing process of an X-ray image detection apparatus. It is FIG. (2) which shows the manufacturing process of an X-ray image detection apparatus. It is explanatory drawing explaining the example of arrangement | positioning of the X-ray image detection apparatus at the time of imaging | photography. It is a figure explaining the 1st modification of FPD. It is a figure explaining the 2nd modification of FPD. It is a figure explaining the 3rd modification of FPD. It is a figure explaining the 4th modification of FPD. It is a figure explaining the 1st modification of a partition. It is a figure explaining the 2nd modification of a partition.

  In FIG. 1, an X-ray image detection apparatus 10 includes a flat panel detector (FPD) 11, a circuit support substrate 12, a control unit 13, and a casing 14 that accommodates these. The housing 14 has a monocoque structure integrally formed of carbon fiber reinforced resin (carbon fiber) that has high X-ray XR permeability, is lightweight, and has high durability. The X-ray image detection apparatus 10 is a portable electronic cassette.

  One side surface of the housing 14 is provided with an opening (not shown) and a lid member (not shown) for closing the opening. When the X-ray image detection apparatus 10 is manufactured, the FPD 11 and the control unit 13 are inserted into the housing 14 from the opening.

  The housing 14 is provided with an irradiation surface 14a that is irradiated with X-rays XR emitted from an X-ray source 80 (see FIG. 8) and transmitted through a subject (patient) 81 (see FIG. 8). On the irradiation surface 14a, a guide line 15 indicating the imageable region of the subject 81 and its center position is formed. The outer frame of the guide line 15 corresponds to the shootable area, and the intersection where the guide line 15 intersects in a cross shape corresponds to the center position of the shootable area.

  In the case 14, the FPD 11 and the circuit support substrate 12 are arranged in this order from the irradiation surface 14a side. The circuit support board 12 supports the circuit board 30 (see FIG. 2) and is fixed to the housing 14. The control unit 13 is disposed on one end side along the short direction in the housing 14.

  The control unit 13 accommodates a microcomputer and a battery (both not shown). The microcomputer communicates with a console (not shown) connected to the X-ray source 80 by wire or wireless to control the operation of the FPD 11.

  In FIG. 2, the FPD 11 includes a phosphor layer (scintillator) 20 that converts X-rays XR into visible light, and a photoelectric conversion panel 21 that converts this visible light into electric charge. The X-ray image detection apparatus 10 is an ISS (Irradiation Side Sampling) type, and the photoelectric conversion panel 21 is arranged on the X-ray XR incident side from the phosphor layer 20. The phosphor layer 20 converts the X-ray XR transmitted through the photoelectric conversion panel 21 into visible light and emits it. The photoelectric conversion panel 21 photoelectrically converts visible light emitted from the phosphor layer 20 and converts it into electric charges.

  The photoelectric conversion panel 21 is attached to the inner surface of the housing 14 on the irradiation surface 14a side via an adhesive layer 22 made of an epoxy resin or the like. As shown in FIG. 3, photodiodes (PD) 43 that perform photoelectric conversion are formed on the surface 21 a of the photoelectric conversion panel 21 in a two-dimensional matrix along the XY directions. Of the surface 21a, an area where the PDs 43 are arranged is an imaging surface.

  As shown in FIG. 3, the phosphor layer 20 has a square lattice shape and a partition wall 23 provided with openings 23a corresponding to the PDs 43 of the photoelectric conversion panel 21, and the openings 23a are filled. And the phosphor 24 thus formed. The partition wall 23 is formed of a glass paste containing glass fine particles and a binder as main components. The partition wall 23 has a refractive index lower than that of the phosphor 24, and the visible light incident on the partition wall 23 from the phosphor 24 is totally reflected when the incident angle is equal to or greater than a predetermined value. Further, the reflectance may be increased by adding filler particles such as titanium oxide, aluminum oxide, and zirconium oxide to the partition wall 23 in addition to the glass fine particles.

  The phosphor layer 20 is supported by a phosphor support substrate 25, and a light reflection film 26 is formed between the phosphor layer 20 and the phosphor support substrate 25. The phosphor support substrate 25 is made of a transparent insulating material such as glass. The light reflecting film 26 is formed of a metal thin film such as aluminum.

  Each opening 23 a of the partition wall 23 is a quadrangle whose planar shape substantially corresponds to the shape of the PD 43. The cross-sectional area of each opening 23 a in the direction parallel to the XY plane is gradually reduced in the direction away from the photoelectric conversion panel 21. The phosphor 24 is filled in each opening 23a from the phosphor support substrate 25 side, and is not completely filled up to the photoelectric conversion panel 21 side. A resin layer 27 is filled on the photoelectric conversion panel 21 side of each opening 23a. Each phosphor 24 has a quadrangular frustum shape (obelisk) having four tapered side surfaces.

  Each opening 23a is completely filled with the phosphor 24 and the resin layer 27, and there is no air layer in each opening 23a. The resin layer 27 protects the partition wall 23 on the photoelectric conversion panel 21 side.

  The refractive index of the resin layer 27 is close to the refractive index of the phosphor 24 in order to increase the emission efficiency of visible light from the phosphor 24 to the photoelectric conversion panel 21 side (suppress reflection on the surface of the resin layer 27). In addition, the refractive index is preferably lower than the refractive index of the phosphor 24. Specifically, since the refractive index of the phosphor 24 is dominated by the refractive index of the binder 24a, the refractive index of the resin layer 27 is close to the refractive index of the binder 24a and lower than the refractive index of the binder 24a. Is preferred. Thereby, the incident efficiency of visible light from the phosphor 24 to the resin layer 27 is improved.

  Two first alignment marks 28 a are formed on the surface 25 a of the phosphor support substrate 25 that supports the phosphor layer 20, outside the region where the phosphor layer 20 and the light reflection film 26 are formed. Each first alignment mark 28a is formed of a metal thin film such as aluminum or nickel. The planar shape of each first alignment mark 28a is, for example, a cross shape.

  The phosphor layer 20 is bonded to the surface 21a of the photoelectric conversion panel 21 through an adhesive layer 29 made of an acrylic bonding agent or the like on the side opposite to the surface on which the light reflecting film 26 is formed. A second alignment mark 28b is formed on the surface 21a of the photoelectric conversion panel 21 at a position facing the first alignment mark 28a. Each second alignment mark 28b is formed of a metal thin film such as aluminum and has the same shape and the same size as the first alignment mark 28a. The first and second alignment marks 28 a and 28 b are used to align the PD 43 and the partition wall 23 when the phosphor layer 20 is bonded to the photoelectric conversion panel 21.

  The circuit support substrate 12 is disposed on the opposite side of the phosphor support substrate 25 from the X-ray XR incident side. The circuit support substrate 12 is fixed to the side portion 14b of the housing 14 with screws or the like. The circuit board 30 is fixed to the lower surface 12a of the circuit support board 12 opposite to the phosphor support board 25 with an adhesive or the like.

  The circuit board 30 and the photoelectric conversion panel 21 are electrically connected via a flexible printed board 31. The flexible printed circuit board 31 is connected to an external terminal 21b provided at an end of the photoelectric conversion panel 21 by a so-called TAB (Tape Automated Bonding) bonding method.

  The flexible printed circuit board 31 is equipped with a gate driver 31a for driving the photoelectric conversion panel 21 and a charge amplifier 31b for converting the electric charge output from the photoelectric conversion panel 21 into a voltage signal. On the circuit board 30, a signal processing unit 30a that generates image data based on the voltage signal converted by the charge amplifier 31b and an image memory 30b that stores image data are mounted. The signal processing unit 30a includes a correlated double sampling circuit, a voltage amplifier, a multiplexer, an A / D converter, and the like. The gate driver 31a, the charge amplifier 31b, the signal processing unit 30a, and the image memory 30b are each configured as an integrated circuit.

  The circuit support board 12 preferably includes an X-ray shielding material such as lead in order to protect the circuit board 30, the signal processing unit 30a, and the image memory 30b from the X-ray XR.

  In FIG. 3, the planar shape of each PD 43 is substantially square (for example, 100 μm × 100 μm square shape), and is spaced apart by a distance Dx in the X direction and is spaced apart by a distance Dy in the Y direction. Yes. The distances Dx and Dy are about 5 to 10 μm. The center of each opening 23 a of the partition wall 23 substantially coincides with the center of each PD 43. The cross-sectional area on the photoelectric conversion panel 21 side of each opening 23a in the direction parallel to the XY plane is smaller than the area of the PD 43. For this reason, the width (interval of the opening 23a) Wx and Wy of the partition wall 23 in the X direction and the Y direction on the photoelectric conversion panel 21 side is larger than the intervals Dx and Dy of the PD 43, respectively.

  The aperture ratio of the partition wall 23 on the photoelectric conversion panel 21 side is preferably 85% or more. The aperture ratio is the ratio of the area of the opening 23a to the area of the phosphor layer 20 in the XY plane. In this case, the thickness of the phosphor layer 20 is preferably 400 μm or more.

In FIG. 4, the phosphor 24 includes a binder (binder) 24a made of a resin or the like and a plurality of phosphor particles 24b dispersed in the binder 24a. The phosphor particles 24b are granular crystals such as GOS (Gd ₂ O ₂ S: Tb) and absorb X-rays XR to generate visible light.

  The photoelectric conversion panel 21 includes an insulating substrate 40 made of non-alkali glass or the like, and a plurality of pixels 41 arranged thereon. The insulating substrate 40 preferably has a thickness of 0.5 mm or less in order to improve the X-ray XR permeability.

  Each pixel 41 includes a thin film transistor (TFT) 42 and a PD 43 connected to the TFT 42. The PD 43 photoelectrically converts visible light generated by the phosphor layer 20 to generate electric charge, and accumulates it. The TFT 42 is a switching element for reading out charges accumulated in the PD 43.

  The TFT 42 is an inverted stagger type, and includes a gate electrode 42g, a source electrode 42s, a drain electrode 42d, and an active layer 42a. The gate electrode 42g is formed on the insulating substrate 40. On the insulating substrate 40, a charge storage electrode 44 is formed in order to increase the charge storage capacity of each pixel 41. Furthermore, a second alignment mark 28 b is formed on the insulating substrate 40. The second alignment mark 28b is preferably formed in the same manufacturing process together with the gate electrode 42g and the charge storage electrode 44.

An insulating film 45 made of silicon nitride (SiN _x ) or the like is formed on the insulating substrate 40 so as to cover the gate electrode 42g and the charge storage electrode 44. An active layer 42a is disposed on the insulating film 45 so as to face the gate electrode 42g. The source electrode 42s and the drain electrode 42d are disposed on the active layer 42a with a predetermined distance therebetween. A part of the drain electrode 42 d extends on the insulating film 45, and faces the charge storage electrode 44 through the insulating film 45 to constitute a capacitor 44 a.

The gate electrode 42g, the source electrode 42s, the drain electrode 42d, and the charge storage electrode 44 are made of aluminum or copper. The active layer 42a is made of amorphous silicon. A TFT protective film 46 made of silicon nitride (SiN _x ) or the like is formed on the insulating film 45 so as to cover the source electrode 42s, the drain electrode 42d, and the active layer 42a.

A first flattening film 47 having a flat surface is formed on the TFT protective film 46 so as to eliminate the uneven structure due to the TFT 42. The first planarizing film 47 is a photosensitive organic material having a low dielectric constant (relative dielectric constant ε _r = 2 to 4) (for example, positive photosensitive acrylic resin: co-weight of methacrylic acid and glycidyl methacrylate). A base polymer composed of a blend is coated with a material obtained by mixing a naphthoquinonediazide-based positive photosensitive agent, etc.) to form a film thickness of 1 to 4 μm.

  A contact hole 48 for exposing the drain electrode 42d is formed in the first planarizing film 47 and the TFT protective film 46. The PD 43 is connected to the drain electrode 42 d of the TFT 42 through the contact hole 48. The PD 43 is formed by a lower electrode 43a, a semiconductor layer 43b, and an upper electrode 43c.

The lower electrode 43a is formed on the first planarizing film 47 so as to cover the inside of the contact hole 48 and the TFT 42, and is connected to the drain electrode 42d. The lower electrode 43a is made of aluminum or indium tin oxide. The semiconductor layer 43b is stacked on the lower electrode 43a. The semiconductor layer 43b is PIN type amorphous silicon, in which an n ⁺ layer, an i layer, and a p ⁺ layer are stacked in order from the bottom. The upper electrode 43c is formed on the semiconductor layer 43b. The upper electrode 43c is made of a highly light-transmitting material such as indium tin oxide or indium zinc oxide.

  On the PD 43 and the first planarization film 47, a second planarization film 49 having a flat surface is formed so as to eliminate the uneven structure due to the PD 43. The second planarizing film 49 is formed by applying a photosensitive organic material similar to that of the first planarizing film 47 to a thickness of 1 to 4 μm.

  A contact hole 50 that exposes the upper electrode 43 c is formed in the second planarization film 49. The common electrode wiring 51 is connected to the upper electrode 43 c through the contact hole 50. The common electrode wiring 51 is commonly connected to the upper electrode 43c of each PD 43, and is used to apply a bias voltage to each upper electrode 43c. The common electrode wiring 51 is made of aluminum or copper.

A protective insulating film 52 is formed on the second planarization film 49 and the common electrode wiring 51. The protective insulating film 52 is formed of silicon nitride (SiN _x ) or the like, like the TFT protective film 46. On the protective insulating film 52, the phosphor layer 20 is bonded via the adhesive layer 29. The resin layer 27 formed in each opening 23 a is in close contact with the adhesive layer 29.

  In FIG. 5, the pixels 41 are arranged in a two-dimensional matrix on the insulating substrate 40. Each pixel 41 includes the TFT 42, the PD 43, and the capacitor 44a as described above. Each pixel 41 is connected to the gate wiring 60 and the data wiring 61 through the TFT 42. The gate wiring 60 extends in the X direction, and a plurality of gate wirings 60 are arranged in the Y direction. A plurality of data lines 61 are arranged in the X direction so as to extend in the Y direction and cross the gate lines 60. The gate wiring 60 is connected to the gate electrode 42 g of the TFT 42. The data line 61 is connected to the drain electrode 42 d of the TFT 42.

  One end of the gate wiring 60 is connected to the gate driver 31a. One end of the data wiring 61 is connected to the charge amplifier 31b. The gate driver 31 a sequentially applies a gate drive voltage to each gate line 60 to turn on the TFT 42 connected to each gate line 60. When the TFT 42 is turned on, the charges accumulated in the PD 43 and the capacitor 44a are output to the data wiring 61.

  The charge amplifier 31b integrates the charges output to the data wiring 61 and converts them into a voltage signal. The signal processing unit 30a generates image data by subjecting the voltage signal output from the charge amplifier 31b to A / D conversion, gain correction processing, and the like. The image memory 30b is composed of a flash memory or the like, and stores image data generated by the signal processing unit 30a. The image data stored in the image memory 30b can be read out via a wired or wireless communication unit (not shown).

  Next, a method for manufacturing the X-ray image detection apparatus 10 will be described. First, as shown in FIG. 6 (A), a metal thin film such as aluminum is formed on the surface 25a of the phosphor support substrate 25 formed of glass or the like by using a known technique such as photolithography or screen printing. The light reflecting film 26 and the first alignment mark 28a are formed. The light reflection film 26 and the first alignment mark 28a may be formed in separate manufacturing processes, but are preferably formed in the same manufacturing process in order to reduce the number of processes.

  As shown in FIG. 6B, a photosensitive paste 70 is applied on the surface 25a of the phosphor support substrate 25 so as to cover the light reflection film 26 and the first alignment mark 28a, and then dried. The photosensitive paste 70 is exposed through the photomask 71.

  As the photosensitive paste 70, for example, a material mainly composed of inorganic fine particles and a photosensitive organic component described in JP-A-2009-231280 can be used. As the inorganic fine particles, glass, ceramic (alumina or cordierite) and the like are preferable, and glass is particularly preferable. As described above, particles such as titanium oxide, aluminum oxide, and zirconium oxide are preferably added to the photosensitive paste 70.

  The photomask 71 is formed with a transmissive portion 71 a corresponding to the planar shape of the opening 23 a of the partition wall 23 described above, and exposure light EL (for example, ultraviolet rays) that has passed through the transmissive portion 71 a is applied to the photosensitive paste 70. Irradiated. The photomask 71 is a so-called gray scale mask, and the transmittance of the transmissive portion 71a changes in the XY direction with respect to the exposure light EL. This transmittance is set according to the tapered shape of the opening 23a.

  In the present embodiment, the photosensitive paste 70 is a positive type. The exposed portion remains by developing the photosensitive paste 70 after exposure with the photomask 71. By baking this, the partition wall 23 is formed as shown in FIG. In the partition wall 23, an opening 23 a having a tapered side surface is formed at a position corresponding to the transmission portion 71 a of the photomask 71. The position of the photomask 71 at the time of exposure is set using the first alignment mark 28a. Therefore, the partition wall 23 is formed with high accuracy with respect to the first alignment mark 28a.

  Then, a phosphor coating solution in which phosphor particles 24b formed of GOS or the like are dispersed in the binder 24a solution (binder solution) is applied onto the partition wall 23, and as shown in FIG. Fill each opening 23a with a phosphor coating solution. At this time, the openings 23 a are not completely filled with the phosphors 24, and the gaps 23 b are left in the upper portions. The depth of the gap 23b is, for example, about 10 to 20 μm. Then, the fluorescent substance 24 is formed by drying the fluorescent substance coating liquid with which the opening part 23a was filled.

  The binder solution is prepared, for example, by dissolving a mixture of polyvinyl butyral resin, urethane resin fat and plasticizer in a mixed solvent of toluene, 2-butanol and xylene and stirring. The phosphor particles 24b are, for example, GOS particles having an average particle diameter of about 5 μm, mixed with the phosphor coating solution, and dispersed by a ball mill. This binder solution is applied using, for example, a doctor blade.

  Then, as shown in FIG. 6E, a resin layer 27 is formed on the surface of the phosphor 24 by filling the gap 23b with a resin material. As a result, each opening 23 a is completely filled with the phosphor 24 and the resin layer 27. As this resin material, it is preferable to use a thermosetting resin or an ultraviolet curable resin having a lower viscosity than the phosphor coating solution.

  Thereafter, as shown in FIG. 7, an adhesive layer 29 made of an acrylic bonding agent or the like is formed on the phosphor layer 20 via the resin layer 27, and the phosphor layer 20 is replaced with the resin layer 27 and the adhesive layer 29. Is attached to the surface 21a of the photoelectric conversion panel 21 via This bonding is performed, for example, by pressing the photoelectric conversion panel 21 against the phosphor layer 20 with a roller (illustrated) from the back surface 21c of the photoelectric conversion panel 21. The photoelectric conversion panel 21 is manufactured by a known semiconductor process.

  When the phosphor layer 20 and the photoelectric conversion panel 21 are bonded to each other, for example, from the opposite side of the phosphor support substrate 25 to the phosphor layer 20, the first and The second alignment marks 28a and 28b are imaged, and the phosphor layer 20 and the photoelectric conversion panel 21 are positioned at a position where the degree of overlap with the first and second alignment marks 28a and 28b is the highest, and then both are positioned. to paste together.

  In the present embodiment, the resin layer 27 is formed on the surface layer in each opening 23a, whereby the adhesion between the adhesive layer 29 and the phosphor layer 20 is improved, and the phosphor layer 20 is attached to the photoelectric conversion panel 21. Misalignment at the time of bonding is prevented.

  The FPD 11 is completed through the above steps. Thereafter, the FPD 11 is attached to the housing 14 via the adhesive layer 22, and the circuit support substrate 12 on which the signal processing unit 30a and the image memory 30b are mounted, the flexible printed circuit board 31 on which the gate driver 31a and the charge amplifier 31b are mounted, By attaching the control unit 13, the X-ray image detection apparatus 10 is completed.

  Next, the operation of the X-ray image detection apparatus 10 will be described. In order to perform imaging using the X-ray image detection apparatus 10, as shown in FIG. 8, a photographer (physician or radiographer) places a subject 81 on the X-ray image detection apparatus 10 and places the subject 81 on the subject 81. The X-ray source 80 is disposed so as to face each other.

  When the photographer operates the console to instruct the X-ray source 80 and the X-ray image detection apparatus 10 to start imaging, the X-ray XR is emitted from the X-ray source 80 and the X-ray XR transmitted through the subject 81 is the X-ray image. The irradiation surface 14a of the detection device 10 is irradiated. The X-ray XR irradiated on the irradiation surface 14 a passes through the casing 14, the adhesive layer 22, the photoelectric conversion panel 21, the adhesive layer 29, and the resin layer 27 in order, and enters the phosphor layer 20.

  In the phosphor layer 20, the plurality of phosphor particles 24b included in the phosphor 24 absorb the incident X-ray XR and generate visible light. Visible light generated by the phosphor particles 24 b propagates through the openings 23 a of the partition walls 23. Specifically, the light emission from the phosphor particles 24 b is isotropic, and the visible light propagating in the direction of the PD 43 passes through the resin layer 27 and the adhesive layer 29 and enters the photoelectric conversion panel 21. On the contrary, the visible light propagating in the direction of the light reflecting film 26 is reflected by the light reflecting film 26, propagates in the direction of the PD 43, and similarly enters the photoelectric conversion panel 21. The visible light propagating in the lateral direction is reflected by the surface of the partition wall 23, propagates in the direction of the photoelectric conversion panel 21 or the light reflecting film 26 according to the reflection direction, and finally enters the photoelectric conversion panel 21. To do. In this way, the visible light generated in each phosphor 24 is suppressed from being diffused by the partition wall 23 and efficiently enters the PD 43 corresponding to each phosphor 24.

  Visible light incident on the photoelectric conversion panel 21 passes through the protective insulating film 52 and the second planarization film 49 and enters the PD 43. Visible light is converted into electric charge by the PD 43, and the converted electric charge is accumulated in the PD 43 and the capacitor 44a. When the X-ray irradiation from the X-ray source 80 is completed, a gate drive voltage is sequentially applied to the gate electrode 42g of the TFT 42 via the gate wiring 60 by the gate driver 31a. As a result, the TFTs 42 arranged in the row direction are sequentially turned on in the column direction, and the charges accumulated in the PD 43 and the capacitor 44 a are output to the data wiring 61 through the turned on TFTs 42.

  The charges output to the data wiring 61 are converted into voltage signals by the charge amplifier 31b and input to the signal processing unit 30a. The signal processing unit 30a generates image data based on the voltage signals for all the pixels 41 and stores the image data in the image memory 30b.

  In the present embodiment, since the X-ray XR is incident on the partition wall 23 from the photoelectric conversion panel 21 side having a large aperture ratio, the light emission amount of the phosphor 24 is large. In addition, since the resin layer 27 is formed on the surface layer in each opening 23a, an air layer is not interposed between the phosphor 24 and the photoelectric conversion panel 21, and the visible from the phosphor 24 toward the photoelectric conversion panel 21 is visible. Light is efficiently incident on the photoelectric conversion panel 21. Both of these synergistically improve the sensitivity of the X-ray image detection apparatus 10.

  In this embodiment, since the width of the partition wall 23 on the phosphor support substrate 25 side is large, it is possible to prevent the phosphor support substrate 25 side from being easily damaged due to the self weight of the phosphor layer 20.

  In the above embodiment, the phosphor layer 20 is bonded to the photoelectric conversion panel 21 via the adhesive layer 29. However, the phosphor layer 20 is directly in contact with the photoelectric conversion panel 21 without providing the adhesive layer 29. You may let them. In the case where the adhesive layer 29 is not provided, the bonding force between the phosphor layer 20 and the photoelectric conversion panel 21 is weak. Therefore, an end sealing portion (see FIG. (Not shown), and it is preferable to join the two through the end sealing portion. The end sealing portion is formed of an ultraviolet curable resin made of an acrylic resin or the like so as to surround the outer periphery of the phosphor layer 20.

  As described above, when the phosphor layer 20 is brought into direct contact with the photoelectric conversion panel 21, since the width of the partition wall 23 on the photoelectric conversion panel 21 side is small, there is a concern about damage to the partition wall 23. Since the partition wall 23 is protected by the resin layer 27 on the photoelectric conversion panel 21 side, damage is prevented.

  Moreover, in the said embodiment, although the resin layer 27 is formed in the space | gap 23b of each opening part 23a of the partition 23, as shown in FIG. 9, without forming the resin layer 27, the space | gap 23b is made into resin material. It may be filled with a part of the adhesive layer 29 formed of

  Moreover, in the said embodiment, although the resin layer 27 is formed so that only the space | gap 23b of each opening part 23a may be filled, as shown in FIG. 10, the height from the surface 25a of the fluorescent substance support substrate 25 is fluorescence. The wall 90 higher than the body layer 20 is formed so as to surround the outer periphery of the phosphor layer 20, and the resin layer is formed so as to fill the space (including the gap 23 b) on the phosphor layer 20 surrounded by the wall 90. 91 may be formed. Thereby, the flatness of the surface of the resin layer 91 is improved.

  In this case, the adhesive layer 29 may be formed on the surface of the resin layer 91, and the phosphor layer 20 may be bonded to the photoelectric conversion panel 21 via the resin layer 91 and the adhesive layer 29. However, the adhesive layer 29 is provided. Instead, the surface of the resin layer 91 may be brought into direct contact with the photoelectric conversion panel 21. Thus, when not providing the adhesion layer 29, it is preferable to provide the above-mentioned edge part sealing part between the fluorescent substance support substrate 25 and the photoelectric conversion panel 21. FIG.

  Moreover, as shown in FIG. 11, the wall part 92 which surrounds the outer periphery of the fluorescent substance layer 20 is formed by filling resin into the opening part 23a located in the outermost part among the opening parts 23a of the partition wall 23, and the wall The aforementioned resin layer 91 may be formed so as to fill a space (including the gap 23b) on the phosphor layer 20 surrounded by the portion 92. In this case as well, the adhesive layer 29 may be formed on the surface of the resin layer 91, or the resin layer 91 may be brought into direct contact with the photoelectric conversion panel 21 without forming the adhesive layer 29.

  Further, as shown in FIG. 14, a part of the resin layer 93 is formed by pressing a sheet-like resin layer 93 that is plastically deformed by heat against the surface of the phosphor layer 20 and applying heat to deform the resin layer 93. The gap 23b may be filled with. Similarly, in this case, the adhesive layer 29 may be formed on the surface of the resin layer 93, or the resin layer 93 may be brought into direct contact with the photoelectric conversion panel 21 without forming the adhesive layer 29. The refractive index of the resin layer 93 is preferably close to the refractive index of the phosphor 24.

  Moreover, in the said embodiment, although the cross-sectional area of the opening part 23a in the direction parallel to XY plane uses the partition 23 which decreases monotonously in the direction away from the photoelectric conversion panel 21, the cross-sectional area of an opening part is photoelectric conversion. If the panel 21 side is larger than the side opposite to the photoelectric conversion panel 21 (if the aperture ratio on the X-ray incident side is larger on the side opposite to the X-ray incident side), any partition is used. Good. For example, as shown in FIG. 13, a partition wall 94 in which the cross-sectional area of the opening 94a changes stepwise may be used. Further, as shown in FIG. 14, a partition wall 95 in which the cross-sectional area of the opening 95 a monotonously decreases to a predetermined position in a direction away from the photoelectric conversion panel 21, changes from a predetermined position to a stepped shape, and becomes constant. It may be used.

  Moreover, in the said embodiment, although the height from the fluorescent substance support substrate 25 of the partition 23 is constant, it replaces with this and a fluorescent substance support substrate is comprised by the part parallel to a X direction, and a part parallel to a Y direction. You may use the partition from which the height from 25 differs. Such a partition is known as a member for a plasma display panel from Japanese Patent Application Laid-Open No. 2009-231280.

  In the above embodiment, the partition wall 23 is formed by photolithography (photosensitive paste method) using a photosensitive paste. However, as described in Japanese Patent Application Laid-Open No. 2009-231280, It is also possible to form using a screen printing method. The partition wall 23 is not limited to glass paste, and may be formed of other materials such as a resist material. Furthermore, a reflective film may be formed on the side surface of the partition wall 23 using a metal or the like.

  In the above embodiment, the square lattice-like partition walls 23 are used as shown in FIG. 3, but stripe-like partition walls having grooves parallel to the X direction or the Y direction may be used. In the case of the square grid-like partition wall 23, since it has a plurality of isolated openings 23a, if uneven application occurs when filling the phosphor coating liquid, the opening 23a is not sufficiently filled with the phosphor coating liquid. However, in the case of stripe-shaped partition walls, there is an advantage that defective filling is unlikely to occur because the phosphor coating liquid flows and fills uniformly in each groove when the phosphor coating liquid is applied.

In the above embodiment, GOS particles are used as the phosphor particles 24b. However, as the phosphor particles 24b, A ₂ O ₂ S: X (where A is any one of Y, La, Gd, and Lu). One, X can be a particle represented by any one of Eu, Tb, and Pr). Further, the phosphor particles 24b may include A ₂ O ₂ S: X containing cerium (Ce) or samarium (Sm) as a coactivator.

  In the above embodiment, the active layer 42a of the TFT 42 is formed of amorphous silicon. Instead, the active layer 42a is formed of amorphous oxide (for example, In-O system), organic semiconductor material, carbon nanotube, or the like. May be.

  In the above embodiment, the semiconductor layer 43b of the PD 43 is formed of amorphous silicon. However, instead of this, an organic photoelectric conversion material (for example, a quinacridone organic compound or a phthalocyanine organic compound) may be formed. . Amorphous silicon has a broad absorption spectrum, but organic photoelectric conversion materials have a sharp absorption spectrum in the visible range, and therefore hardly absorb electromagnetic waves other than visible light generated in the phosphor layer 20, and noise. Can be suppressed.

  In the above embodiment, X-rays are used as radiation. However, radiation other than X-rays such as γ-rays and α-rays may be used. Furthermore, in the above embodiment, the present invention has been described by taking an electronic cassette as a portable radiological image detection device as an example, but the present invention is a standing radiograph or radiological image detection device, It can also be applied to a mammography apparatus.

DESCRIPTION OF SYMBOLS 10 X-ray image detection apparatus 12 Circuit support substrate 20 Phosphor layer 21 Photoelectric conversion panel 23 Partition 23a Opening 23b Space | gap 24 Phosphor 24a Binder 24b Phosphor particle 25 Phosphor support substrate 26 Light reflecting film 27 Resin layer 29 Adhesive layer 41 Pixel 43 Photodiode

Claims (10)

A photoelectric conversion panel having an imaging surface in which pixels including photodiodes that perform photoelectric conversion are two-dimensionally arranged;
A partition wall and a phosphor, and the partition wall is disposed corresponding to each of the photodiodes, and a cross-sectional area in a direction parallel to the imaging surface is closer to the photoelectric conversion panel than the photoelectric conversion panel side. Has a larger opening than the opposite side, the phosphor is filled in each opening, leaving a gap on the photoelectric conversion panel side, and a phosphor layer for converting radiation into visible light, and
A resin layer formed in the gap;
A radiological image detection apparatus comprising:   The radiation image detection apparatus according to claim 1, wherein the photoelectric conversion panel and the phosphor layer are arranged in the order of the photoelectric conversion panel and the phosphor layer from the side on which the radiation is incident. .   In the phosphor layer, the surface on which the resin layer is formed is bonded to the photoelectric conversion panel via an adhesive layer, or the surface on which the resin layer is formed directly contacts the photoelectric conversion panel. The radiation image detection apparatus according to claim 2, wherein the radiation image detection apparatus is in contact with the radiation image detection apparatus.   The radiographic image detection apparatus according to claim 3, wherein each of the openings gradually decreases in cross-sectional area in a direction away from the photoelectric conversion panel.   The radiation image detection apparatus according to claim 3, wherein a light reflection layer that reflects the visible light is formed on a surface of the phosphor layer opposite to the photoelectric conversion panel.   The radiographic image detection apparatus according to claim 5, wherein the phosphor layer is formed on the phosphor support substrate via the light reflection layer.   The radiographic image detection apparatus according to claim 3, wherein the phosphor includes a binder and phosphor particles dispersed in the binder.   The radiographic image detection apparatus according to claim 7, wherein the partition wall has a refractive index lower than that of the phosphor.   The radiation image detection apparatus according to any one of claims 3 to 8, wherein an aperture ratio of the partition wall on the photoelectric conversion panel side is 85% or more.   The radiographic image detection apparatus according to claim 9, wherein the phosphor layer has a thickness of 400 μm or more.

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