JP2008292401A - Radiation detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radiation detector 11 of higher manufacturability free from such a problem as found in using an electrostatic chuck and a vacuum chuck, when a plurality of photoelectric converting substrates 14 are arranged on a base 12 to increase an area. <P>SOLUTION: This radiation detector has a structure where edge portions of photoelectric converting substrates 14 are projected from an edge portion of the base 12. The edge portions of the photoelectric converting substrates 15 projecting from the edge portion of the base 12 are held by a mechanical chuck mechanism, and thereby the photoelectric converting substrates 14 are carried on the base 12 and disposed while the chuck mechanism is prevented from interfering with the base 12. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a radiation detector that takes a radiation image of a large area by arranging a plurality of photoelectric conversion substrates.

  As a medical X-ray diagnostic apparatus, a planar X-ray detector that converts an X-ray image transmitted through a human body into an electric signal and outputs the electric signal has been put into practical use. Many X-ray detectors currently in practical use include a photoelectric conversion substrate in which a plurality of photoelectric conversion elements such as photodiodes are two-dimensionally arranged on a substrate to form a light receiving portion, and a photoelectric conversion substrate of this photoelectric conversion substrate. A scintillator layer formed on the light receiving portion, and converts the X-rays transmitted through the human body or the like into light by the scintillator layer, and converts the light into an electric signal by the photoelectric conversion element of the photoelectric conversion substrate. The image converted into is displayed on the monitor. A photoelectric conversion substrate is formed by forming a circuit board formed by two-dimensionally arranging thin film transistors (TFTs), and forming two-dimensionally arranging photoelectric conversion elements electrically connected to the thin film transistors on the circuit board. Yes.

  By the way, X-ray detectors with a large area are necessary for X-ray imaging of the chest, etc. However, the larger the area, the more the yield deterioration during the manufacture of the photoelectric conversion substrate and the enlargement of the photoelectric conversion substrate manufacturing apparatus are required. This increases the manufacturing cost of the photoelectric conversion substrate.

As a solution, a photoelectric conversion substrate having a light receiving area smaller than the entire light receiving area as an X-ray detector is used, and a plurality of photoelectric conversion substrates are arranged to increase the area, thereby reducing the yield per photoelectric conversion substrate. Can be prevented, and the manufacturing cost can be reduced. In this case, a base having an area larger than the area constituted by the plurality of photoelectric conversion substrates is used, and the plurality of photoelectric conversion substrates are arranged with an adhesive interposed in a region inside the periphery of the surface of the base. (For example, refer to Patent Document 1).
JP 2002-48872 A (3rd page, FIG. 1-3)

  Conventionally, when a plurality of photoelectric conversion substrates are arranged side by side to increase the area, it is necessary to transport and arrange the photoelectric conversion substrate to a region inside the periphery of the surface of the base. Even if the chuck is to be transported, it cannot be used because the chuck interferes with the base, and the surface of the photoelectric conversion substrate needs to be transported while being held by an electrostatic chuck or a vacuum chuck.

  However, in the electrostatic chuck, there is a possibility that the photoelectric conversion element may be destroyed by static electricity during transportation, and in the vacuum chuck, since the environment is in the atmosphere, there is a problem that it cannot be used depending on the environmental conditions. is there.

  The present invention has been made in view of such a point, and in the case of increasing the area by arranging a plurality of photoelectric conversion substrates on a base, as in the case of using an electrostatic chuck or a vacuum chuck at the time of manufacture. An object of the present invention is to provide a radiation detector that is free from defects and has good manufacturability.

  The present invention provides a plurality of photoelectric conversion substrates having a substrate and a light receiving portion formed by two-dimensionally arranging a plurality of photoelectric conversion elements on the substrate, and the plurality of photoelectric conversion substrates so that the light receiving portions are adjacent to each other. It comprises a base arranged side by side and a scintillator layer formed directly over the entire light receiving part of the plurality of photoelectric conversion substrates, and the edge of each photoelectric conversion substrate protrudes from the edge of the base Is.

  According to the present invention, since the edge of each photoelectric conversion substrate protrudes from the edge of the base, the edge of the photoelectric conversion substrate protruding from the edge of the base is mechanically held during manufacturing. By doing so, the photoelectric holding substrate can be transported and arranged on the base without the mechanical holding mechanism interfering with the base, and there is a problem like when using an electrostatic chuck or vacuum chuck The productivity can be improved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  1 to 5 show a first embodiment.

  As shown in FIGS. 1 to 3, the radiation detector 11 includes a base 12 made of, for example, glass, and a photoelectric conversion substrate that is a plurality of imaging substrates via an adhesive 13 on the base 12. 14 are fixed side by side so as to be adjacent to each other in a plane. Here, four rectangular photoelectric conversion substrates are formed on the rectangular base 12 in a state where two of the four sides of the rectangular photoelectric conversion substrate 14 are adjacent to the other photoelectric conversion substrate 14. 14 are arranged side by side so as to be adjacent to each other in plan view, and a large area and one rectangular light receiving surface 15 are formed.

  The photoelectric conversion substrate 14 includes a substrate 18 made of, for example, glass. On the substrate 18, thin film transistors (TFTs) are two-dimensionally arranged, and on each of these thin film transistors, for example, a photodiode or the like is formed. The photoelectric conversion elements are two-dimensionally arranged. A light receiving portion 19 that converts light into an electric signal is formed by the plurality of thin film transistors and the plurality of photoelectric conversion elements.

  Among the four sides of the photoelectric conversion substrate 14, for two sides adjacent to the other photoelectric conversion substrate 14, a light receiving portion 19 is formed up to the edge of those sides, and the remaining two not adjacent to the other photoelectric conversion substrate 14. With respect to the side, a gap is provided between the side and the light receiving unit 19. A plurality of electrode pads 20 serving as a circuit portion connected to the photoelectric conversion element and the thin film transistor are formed in the spaced portion.

  Then, in a state where the four photoelectric conversion substrates 14 are arranged side by side on the base 12, the outer peripheral portions of the photoelectric conversion substrates 14 are formed so as to protrude from the outer edge of the base 12. That is, protrusions 21 that protrude from the outer edge of the base 12 are formed on two sides of the four sides of the photoelectric conversion substrate 14 that are not adjacent to the other photoelectric conversion substrate 14. Therefore, in a state where the four photoelectric conversion substrates 14 are arranged side by side on the base 12, the width L1 in the direction in which the photoelectric conversion substrates 14 are arranged on the base 12 is wider than the width L2 of the base 12. .

  At least a part of the electrode pad 20 is formed on the protruding portion 21 of the photoelectric conversion substrate 14, and can be held by a mechanical chuck mechanism without interfering with the base 12 in the corner region of the protruding portion 21, for example. A holding portion 22 is formed.

  In this way, by adopting a structure in which the edge of each photoelectric conversion substrate 14 protrudes from the edge of the base 12, the edge of the photoelectric conversion substrate 14 protruding from the edge of the base 12 is machined during manufacturing. By holding with a typical chuck mechanism, the photoelectric conversion substrate 14 can be transported and arranged on the base 12 without the chuck mechanism interfering with the base 12, and the above-described electrostatic chuck or vacuum chuck can be mounted. There is no problem as in the case of use, and productivity can be improved.

  As shown in FIG. 4, the adhesive 13 is made of, for example, an acrylic or epoxy ultraviolet curable resin and is made of a highly viscous material capable of maintaining the coating shape, and has a frame along the periphery of the base 12. A plurality of islands coated with the adhesive 13 in an island-like arrangement in a random or aligned manner in the inner region of the frame-shaped adhesive 13a. A shaped adhesive portion 13b is formed.

  Then, the four photoelectric conversion substrates 14 arranged on the base 12 via the adhesive 13 are uniformly weighted, or the base 12 is uniformly weighted to the four photoelectric conversion substrates 14 and the adhesive Adhesion is achieved by irradiating 13 with ultraviolet rays and curing.

  At this time, since there is a gap 23 between the adjacent photoelectric conversion substrates 14, as shown in FIG. 5, the adhesive 13 of the frame-shaped adhesive portion 13a crushed by the photoelectric conversion substrate 14 is adjacent to the photoelectric conversion substrate 14. The gap 23 is filled by being pushed out to the surface side of the photoelectric conversion substrate 14 through the gap 23 therebetween.

  Further, since a plurality of island-shaped adhesive portions 13b are formed inside the frame-shaped adhesive portion 13a, the four photoelectric conversion substrates 14 are uniformly weighted with respect to the base 12, or the four bases 12 are provided. By uniformly applying weight to the photoelectric conversion substrate 14, the warp and the inclination of each photoelectric conversion substrate 14 are corrected while the frame-shaped adhesion portions 13 a and the plurality of island-shaped adhesion portions 13 b are crushed, and four sheets are obtained. The photoelectric conversion substrates 14 can be arranged on the same plane, and the steps of the adjacent photoelectric conversion substrates 14 can be eliminated as much as possible.

  As shown in FIGS. 3 and 5, light having sensitivity that allows the light receiving unit 19 to receive incident radiation on the light receiving units 19 of the four photoelectric conversion substrates 14 arranged on the base 12. A scintillator layer 24 having a columnar crystal structure to be converted into is directly formed. The scintillator layer 24 has a thickness of 100 μm to 1000 μm, and the material of the scintillator layer 24 is often CsI subjected to TI doping with good light emission efficiency.

  The scintillator layer 24 is formed on the inner side of the position of the frame-shaped adhesive portion 13a.In other words, the frame-shaped adhesive portion 13a is formed on the outer side of the scintillator layer 24, and the scintillator layer 24 is extruded into the gap 23 and buried. It is not formed on the adhesive 13 of the adhesive part 13a.

  As described above, the scintillator layer 24 integrally formed on the four photoelectric conversion substrates 14 has a difference in light emission amount between the stepped portion and the portion other than the stepped portion due to the influence of the gap or the step between the adjacent photoelectric conversion substrates 14. However, as described above, the steps of the adjacent photoelectric conversion substrates 14 can be eliminated as much as possible, so that the difference in the amount of emitted light can be reduced.

  Further, a protective film 25 is formed on the scintillator layer 24 to cover the scintillator layer 24 so as to be sealed and protect it from external moisture. The formation of the protective film 25 is performed in a dehumidifying environment.

  The protective film 25 is formed from the scintillator layer 24 to the substrate 18 of the photoelectric conversion substrate 14 outside the scintillator layer 24 so as to seal the scintillator layer 24 on the photoelectric conversion substrate 14.

  However, since there is a gap 23 between the adjacent photoelectric conversion substrates 14, there is a possibility that the protective film 25 may not be able to seal the gap 23, but the photoelectric conversion substrate 14 has a gap 23 between the adjacent photoelectric conversion substrates 14. Since the adhesive 13 of the frame-shaped adhesive portion 13a is extruded on the surface side to fill the gap 23, the protective film is formed from the scintillator layer 24 to the substrate 18 of the photoelectric conversion substrate 14 outside the scintillator layer 24. 25 contacts the adhesive 13 of the frame-shaped adhesive portion 13a that is pushed out into the gap 23 between the adjacent photoelectric conversion substrates 14 and fills the gap 23, and seals the gap 23. Therefore, the scintillator layer 24 can be reliably sealed by the protective film 25 and can be protected from external moisture.

  For example, titanium dioxide particles are bound to the protective film 25 with a resin for the purpose of preventing moisture removal of the scintillator layer 24 and preventing the scintillator layer 24 from peeling off and reflecting the light converted by the scintillator layer 24 toward the light receiving unit 19. Used.

  Thus, since the scintillator layer 24 can be reliably sealed by the protective film 25 and protected from external moisture, it is possible to prevent a decrease in MTF (Modulation Transfer Function) characteristics of the scintillator layer 24 due to moisture.

  Next, FIG. 6 shows a second embodiment.

  After applying the adhesive 13 to the base 12 to form the frame-like adhesive portion 13a and the plurality of island-like adhesive portions 13b inside the frame-like adhesive portion 13a, the low-viscosity adhesive 27 having a lower viscosity than the adhesive 13 Is filled inside the frame-shaped bonding portion 13a, and the photoelectric conversion substrates 14 are bonded. For this low-viscosity adhesive 27, for example, an acrylic or epoxy UV curable resin is used, as in the case of the adhesive 13. ing.

  In this way, by filling the inside of the frame-shaped adhesive portion 13a with a low-viscosity adhesive 27 having a lower viscosity than the adhesive 13, the adhesive effect of the low-viscosity adhesive 27 in addition to the adhesive 13 allows the photoelectric conversion substrate 14 to The effect of correcting warpage and tilt can be improved.

  Note that the number of photoelectric conversion substrates 14 arranged on the base 12 is not limited to four, and may be two. The edge of the photoelectric conversion substrate 14 is protruded from the edge of the base 12 without being limited to two sides, as long as at least one side protrudes or only a part of the photoelectric conversion substrate 14 protrudes. .

It is a front view in the state where a plurality of photoelectric conversion boards were arranged on the base of the radiation detector which shows a 1st embodiment of the present invention. It is sectional drawing of a radiation detector same as the above. It is a partial expanded sectional view containing the scintillator layer and protective layer of a radiation detector same as the above. It is a front view of the state which apply | coated the adhesive agent to the base of a radiation detector same as the above. It is a partial expanded sectional view which shows between adjacent photoelectric conversion boards of a radiation detector same as the above. It is a front view of the state which apply | coated the adhesive agent to the base of the radiation detector which shows the 2nd Embodiment of this invention.

Explanation of symbols

11 Radiation detector
12 base
13 Adhesive
14 Photoelectric conversion board
18 Board
19 Receiver
20 Electrode pads as circuit parts
24 Scintillator layer
25 Protective film
27 Low viscosity adhesive

Claims (7)

A plurality of photoelectric conversion substrates having a substrate and a light receiving portion formed by two-dimensionally arranging a plurality of photoelectric conversion elements on the substrate;
A plurality of photoelectric conversion substrates arranged side by side so that the light receiving portions are adjacent to each other;
A scintillator layer formed directly over the entire light receiving portion of the plurality of photoelectric conversion substrates,
A radiation detector comprising: an edge of each photoelectric conversion substrate protruding from an edge of the base. The radiation detector according to claim 1, wherein the width of the plurality of photoelectric conversion substrates arranged on the base is wider than the width of the base. An adhesive is provided between the base and the plurality of photoelectric conversion substrates to bond the base and the plurality of photoelectric conversion substrates, and the adhesive is arranged in a frame shape corresponding to the peripheral shape of the base. The radiation detector according to claim 1 or 2, wherein a plurality of island-shaped adhesives are arranged inside the frame-shaped adhesive. Part of the frame-shaped adhesive enters between the plurality of photoelectric conversion substrates,
The radiation detection according to claim 3, further comprising a protective film that covers the scintillator layer and that seals in contact with a frame-like adhesive that has penetrated between the plurality of photoelectric conversion substrates and between the plurality of photoelectric conversion substrates. vessel. The radiation detector according to claim 3 or 4, wherein a low-viscosity adhesive having a lower viscosity than the frame-shaped and island-shaped adhesive before curing is disposed inside the frame-shaped adhesive. The at least part of the circuit part electrically connected to the photoelectric conversion element is provided on the edge part of the photoelectric conversion substrate protruding from the edge part of the base. Radiation detector. The radiation detector according to claim 1, wherein the scintillator layer has a thickness of 100 μm to 1000 μm.

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