JP2017138256A - Radiation detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radiation detection device capable of improving EMC performance.SOLUTION: A radiation detection device (10) of the present invention includes a sensor unit (13) that is mounted on a front surface (14a) of a printed circuit board (14) to detect radiation. The sensor unit is enclosed inside a metallic shield body (18). The metallic shield body is positioned to cover both surfaces of the printed circuit board. The metallic shield body comprises a separately provided first metallic shield (31) and second metallic shield (32). The first metallic shield is disposed on the front surface of the printed circuit board to cover the sensor unit. The second metallic shield is disposed on a back surface (14b) of the printed circuit board to cover an area thereof corresponding to where the sensor unit is mounted.SELECTED DRAWING: Figure 11

Description

  The present invention relates to a radiation detection apparatus that measures a radiation dose.

  As a radiation exposure dose measuring instrument conventionally used, there is a radiation detection device including a dosimeter (see, for example, Patent Document 1). A radiation detector including a radiation detection element is arranged inside the radiation detection device, and the radiation dose can be measured.

JP 2007-24497 A

  In a radiation detection apparatus, in order to detect radiation with high accuracy, high EMC (Electro Magnetic Compatibility) performance is required, and it has been desired to suppress electromagnetic waves from entering the radiation detection element. Therefore, as a result of repeated intensive trial and error, the present inventor has found that not only electromagnetic waves entering toward the sensitive surface of the radiation detection element but also electromagnetic waves entering from all directions are affected. The present invention has been devised based on this finding.

  This invention is made | formed in view of this point, and it aims at providing the radiation detection apparatus which can improve EMC performance.

  The radiation detection apparatus of the present invention includes a sensor unit that is mounted on one surface of a predetermined substrate and detects radiation, and a metal shield that covers both surfaces of the substrate and accommodates the sensor unit therein. It is characterized by that.

  According to this configuration, since the metal shield body covers both surfaces of the substrate including the sensor unit, not only the electromagnetic wave toward the surface on which the sensor unit is mounted but also the electromagnetic wave toward the opposite surface enters the sensor unit. Can be suppressed. Thereby, the electromagnetic wave which goes to both surfaces of a board | substrate can be shielded with a metal shield, EMC performance can be improved, and the detection accuracy of a radiation can be kept favorable.

  According to the present invention, since the metal shield body that accommodates the sensor unit covers both surfaces of the substrate, the EMC performance can be improved.

It is a longitudinal cross-sectional view of the radiation detection apparatus which concerns on embodiment. It is a front view of a printed circuit board and a sensor unit. FIG. 3 is a schematic exploded perspective view of FIG. 2. It is a schematic perspective view of a printed circuit board and a metal shield body. It is a schematic perspective view of the printed circuit board and metal shield body which were seen from the opposite side to FIG. It is an explanatory perspective view of a state just before attaching a magnetic shield body. It is a perspective view for explanation in the state where a magnetic shield body was attached. It is a perspective view for description of the state which looked at FIG. 7 from the other side. It is an explanatory perspective view which shows the halfway state which attaches an electromagnetic wave absorption sheet. It is a perspective view for description of the form of the electromagnetic wave absorption sheet after attachment. It is explanatory drawing about the electromagnetic wave shielding effect | action to a sensor unit.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, this invention is not limited to the following embodiment, It can deform | transform suitably and implement in the range which does not change the summary. In the following drawings, some components may be omitted for convenience of explanation.

  FIG. 1 is a longitudinal sectional view of a radiation detection apparatus according to an embodiment. As shown in FIG. 1, the radiation detection apparatus 10 includes a sensor unit 13, a printed circuit board (substrate) 14, a notification unit 16, and a display unit 17 disposed in a housing 11. The sensor unit 13 is mounted on a surface 14 a that is one surface of the printed circuit board 14. Further, the front surface 14 a side and the other surface 14 b side of the printed circuit board 14 are covered with a metal shield body 18. The sensor unit 13 is housed inside the metal shield body 18, and the metal shield body 18 suppresses electromagnetic waves from entering the sensor unit 13. The notification unit 16 includes a buzzer, a speaker, and the like that notify a warning sound or the like by a signal processed by the CPU of the printed circuit board 14. The display unit 17 displays the radiation dose detected by the sensor unit 13. The mounting unit 20 is provided so that the radiation detection apparatus 10 can be mounted on clothes or the like. In addition, illustration is abbreviate | omitted in the below-mentioned magnetic shield body and electromagnetic wave absorption sheet attached to the metal shield body 18 of FIG.

  Subsequently, a configuration around the printed circuit board 14 and the sensor unit 13 built in the radiation detection apparatus 10 will be described along a manufacturing procedure of the configuration. This manufacturing procedure is performed in the order of a sensor unit attachment step, a metal shield body attachment step, a magnetic shield body attachment step, and an electromagnetic wave absorbing sheet attachment step.

  First, as shown in FIGS. 2 and 3, a sensor unit mounting step is performed. FIG. 2 is a front view of the printed circuit board and the sensor unit. FIG. 3 is a schematic exploded perspective view of FIG. The sensor unit mounting step is performed by mounting the sensor unit 13 on the surface 14a of the printed circuit board 14 by bonding or the like. In bonding, a spacer or the like may be interposed between the surface 14a of the printed circuit board 14 and the sensor unit 13, or the sensor unit 13 may be mounted by pasting with a double-sided tape instead of bonding.

  Here, the configuration of the sensor unit 13 will be described. The sensor unit 13 includes a sensor unit substrate 24 made of a printed circuit board, a radiation detection element 25 mounted on the sensor unit substrate 24, and an amplification circuit mounted on the sensor unit substrate 24 in the vicinity of the radiation detection element 25. 26 and a sensor metal shield 28 that covers the radiation detection element 25 and the amplifier circuit 26. The amplification circuit 26 amplifies the radiation detection signal from the radiation detection element 25 and outputs it to various circuits such as a CPU located inside the sensor metal shield 28 in the same manner as the amplification circuit 26.

  The radiation detection element 25 is, for example, a diode structure made of a silicon pn junction. In the radiation detection element 25 having a diode structure, a reverse bias voltage is applied so as to form a depletion layer having a predetermined size at the pn junction, which is generated directly and indirectly by radiation in the depletion layer. Electrons and holes are output as current pulses. The configuration of the radiation detection element 25 is not limited to this.

  The sensor metal shield 28 is formed using copper, aluminum or the like having high electrical conductivity. The sensor metal shield 28 is formed in a box shape that shields electromagnetic waves and forms a shield space therein. Specifically, a substantially rectangular main surface portion 28a positioned in parallel with the sensor unit substrate 24 and a side surface portion 28b extending in the thickness direction of the sensor unit substrate 24 from four sides serving as outer edges of the main surface portion 28a are provided. Yes. 3 is attached to the sensor unit substrate 24 by soldering or the like.

  After performing the sensor unit mounting step, a metal shield body mounting step is performed. In this metal shield body attaching step, the metal shield body 18 is disposed so as to sandwich the sensor unit 13 from both sides in the thickness direction (vertical direction in FIG. 3) of the printed board 14. Then, the metal shield 18 is attached to the printed board 14 by soldering or the like.

  Here, the metal shield body 18 will be described below. The metal shield body 18 is formed using copper, aluminum or the like having high electrical conductivity. The metal shield body 18 includes a first metal shield 31 and a second metal shield 32 that are provided separately. The first metal shield 31 is provided so as to cover the entire sensor unit 13 on the surface 14 a of the printed circuit board 14. The second metal shield 32 is provided on the back surface 14 b of the printed circuit board 14. The metal shields 31 and 32 are provided so as not to protrude from the outer periphery of the printed circuit board 14 but to fit within the surface. Each of the metal shields 31 and 32 is also formed in a box shape that shields electromagnetic waves and forms a shield space inside, similarly to the sensor metal shield 28. Specifically, substantially rectangular main surface portions 31a and 32a positioned in parallel with the printed circuit board 14, and side surface portions 31b and 32b extending in the thickness direction of the printed circuit board 14 from four sides serving as outer edges of the main surface portions 31a and 32a, It has.

  As shown in FIGS. 4 and 5, the main surface portion 31 a of the first metal shield 31 and the main surface portion 32 a of the second metal shield 32 are formed in substantially the same shape when viewed from the thickness direction. Moreover, the attachment position of the surface direction of the printed circuit board 14 in each metal shield 31 and 32 is substantially the same. Therefore, the second metal shield 32 is disposed so as to face the first metal shield 31 with the printed board 14 interposed therebetween, and is provided so as to cover a region corresponding to the mounting portion of the sensor unit 13.

  Returning to FIG. 3, the lower end portion in FIG. 3 of the side surface portion 31 b in the first metal shield 31 and the upper end portion in FIG. 3 of the side surface portion 32 b in the second metal shield 32 are attached to the printed circuit board 14 by soldering. In the printed circuit board 14, a plurality of holes 14c arranged in two rows along the end portions of the side surface portions 31b and 32b are formed at the attachment positions of the side surface portions 31b and 32b. These holes 14c are formed at a predetermined interval (for example, an interval of 0.5 to 1.0 mm) in the arrangement direction, and are formed over the entire circumference of the side surface portions 31b and 32b or a part of the entire circumference. Is done. Moreover, the edge part of each side part 31b and 32b is arrange | positioned so that it may overlap between the row | line | column of the hole 14c used as 2 rows, or a row | line | column. Copper plating (conductor) is applied to the inner peripheral surface of the hole 14c, and the solder (conductor) used for soldering the metal shields 31 and 32 flows into the hole 14c and comes into contact with the copper plating. . Thus, by soldering the metal shields 31 and 32 to the printed circuit board 14, the first metal shield 31 and the second metal shield 32 are electrically connected by the copper plating and the solder in the holes 14c. .

  After the metal shield body mounting step, the magnetic shield body mounting step is performed. FIG. 6 is an explanatory perspective view of a state immediately before the magnetic shield body is attached, and FIG. 7 is an explanatory perspective view of a state where the magnetic shield body is attached. In the magnetic shield body attaching step, as shown in FIG. 6, a flat magnetic shield body 35 with various cuts is prepared. Then, while covering the outer peripheral surface of the first metal shield 31 with the magnetic shield body 35, the magnetic shield body 35 is mountain-folded at a mountain fold portion 35A illustrated by a dotted line in FIG. Fold it up at the valley. As a result, as shown in FIG. 7, the magnetic shield body 35 is formed in a box shape so as to surround the first metal shield 31 from the outside, and the five surfaces of the first metal shield 31 other than the printed board 14 side are magnetic shields. Covered with a body 35. The magnetic shield body 35 is attached to the outer peripheral surface of the first metal shield 31 by pasting with a double-sided tape or the like.

  Also in the magnetic shield body 35, the thickness of the printed circuit board 14 from the substantially rectangular main surface part 35a positioned in parallel with the printed circuit board 14 and the four sides serving as the outer edges of the main surface part 35a in a state attached to the first metal shield 31. And a side surface portion 35b extending in the direction. An extended surface portion 35c is formed continuously on a part of the side surface portion 35b, and is provided along the surface 14a of the printed circuit board 14. Further, as shown in FIG. 8, a winding surface portion 35 d that is bent so as to be wound around the end portion of the printed circuit board 14 is formed on the other part of the side surface portion 35 b.

  The magnetic shield body 35 is a nanocrystalline soft magnetic material, which can be exemplified by crystallizing an amorphous alloy, and forms a magnetic shield space inside so as to block magnetism from the outside. In particular, the magnetic shield body 35 exhibits a good shielding effect against high-frequency electromagnetic waves in the GHz band.

  After carrying out the magnetic shield body attaching step, an electromagnetic wave absorbing sheet attaching step is carried out. FIG. 9 is an explanatory perspective view showing an intermediate state in which the electromagnetic wave absorbing sheet is attached, and FIG. 10 is an explanatory perspective view of the form of the electromagnetic wave absorbing sheet after being attached. In the electromagnetic wave absorbing sheet attaching step, as shown in FIG. 9, an electromagnetic wave absorbing sheet 38 formed in a band shape is prepared. The width of the electromagnetic wave absorbing sheet 38 is slightly larger than or substantially the same as the height of the side surface portion 35 b of the magnetic shield body 35. Then, the electromagnetic wave absorbing sheet 38 is bent so as to be wound along the side surface portion 35 b which is the outer peripheral side of the magnetic shield body 35. Thus, the electromagnetic wave absorbing sheet 38 is provided in a rectangular tube shape (see FIG. 10) so as to surround the four surfaces on the side surface portion 35b side of the magnetic shield body 35. The electromagnetic wave absorbing sheet 38 is attached to the outer peripheral surface of the magnetic shield body 35 by sticking with a double-sided tape or the like.

  The electromagnetic wave absorbing sheet 38 is formed by uniformly mixing a metal powder with rubber and then forming it into a sheet shape, and is made of a material having excellent magnetic permeability characteristics and electromagnetic wave absorbing characteristics. The electromagnetic wave absorbing sheet 38 absorbs the electromagnetic wave by converting the incident electromagnetic wave into heat energy and losing magnetism. The magnetic shield body 35 and the electromagnetic wave absorbing sheet 38 do not affect the energy characteristics of the radiation detected by the radiation detection element 25 or have only a very small effect.

  Here, returning to FIG. 1, a magnetic shield body 50 is provided at a position on the inner surface of the housing 11 and facing the sensor unit 13. The magnetic shield body 50 is made of the same material as the magnetic shield body 35 described above and has the same function. Accordingly, the shielding effect can be exerted also on the inner surface of the housing 11 provided with the magnetic shield body 50. Note that the magnetic shield body 50 may be additionally provided on the back side of the display unit 17 or on the inner surface on the opposite side of the housing 11 where the magnetic shield body 50 is provided.

  FIG. 11 is an explanatory diagram of the electromagnetic wave shielding action on the sensor unit. As shown in FIG. 11, in the sensor unit 13, the electromagnetic wave W tends to enter the radiation detection element 25 from all surrounding directions in various electromagnetic environments. The electromagnetic wave W is mainly shielded or attenuated by the metal shields 31 and 32, and the electromagnetic wave W entering the radiation detection element 25 can be suppressed. Therefore, in the present embodiment, not only the electromagnetic wave W directed toward the front surface 14a of the substrate 14 but also the electromagnetic wave W directed toward the back surface 14b can be prevented from entering the radiation detection element 25. As a result, the EMC performance of the radiation detection apparatus 10 can be improved, and the radiation detection accuracy can be kept good.

  Here, since the first metal shield 31 and the second metal shield 32 are electrically connected as described above, their potentials are equalized. Thereby, the shield effect of each metal shield 31 and 32 located in the front and back of the board | substrate 14 can be heightened, and the approach of electromagnetic wave W can be suppressed better.

  Further, as shown by the dotted line in FIG. 11, the electromagnetic wave W <b> 1 shielded by the first metal shield 31 tends to wrap around from the end facing the surface 14 a of the first metal shield 31. However, in this embodiment, since the electromagnetic wave absorbing sheet 38 is provided as described above, even if the electromagnetic wave W1 tries to wrap around, the electromagnetic wave absorbing sheet 38 can absorb and weaken it as indicated by the electromagnetic wave W2 in the figure. And the influence on the radiation detection element 25 can be further reduced. Thereby, noise resistance can be improved with respect to electromagnetic waves in a wide frequency band.

  As described above, according to the present embodiment, since the electromagnetic wave to the sensor unit 13 can be shielded as described above, conformity to the MIL standard that defines the EMC performance can be realized.

  The present invention is not limited to the above embodiment, and can be implemented with various modifications. Moreover, there is no restriction | limiting in particular about the numerical value, dimension, material, and direction which were demonstrated by the said embodiment. Other modifications may be made as appropriate without departing from the scope of the object of the present invention.

  For example, the metal shield body 18 can be variously modified, and may be configured to protrude from the outer edge of the substrate 14, or further, the outer edge of the substrate 14 may be separated from the front and back of the substrate 14 as in the above embodiment. You may form so that it may wrap around. Also in this configuration, the metal shields 18 positioned on the front and back of the substrate 14 may be attached by solder flowing into the holes 14c, and the metal shields 18 positioned on the front and back of the substrate 14 may be electrically connected to each other.

  Moreover, the attachment position of the electromagnetic wave absorbing sheet 38 can be variously changed as long as it can absorb the electromagnetic wave that tries to go around the end of the metal shield 18. For example, among the four side surface portions 35b of the magnetic shield body 35, the magnetic shield body 35 may be provided on at least one side surface portion 35b, or may be provided on all or a part of the main surface portion 35a.

  Further, the electromagnetic wave absorbing sheet 38 may be provided so as to be sandwiched between the side surface portion 31 b of the first metal shield 31 and the side surface portion 35 b of the magnetic shield body 35. Further, the magnetic shield body 35 may be omitted, and the electromagnetic wave absorbing sheet 38 may be provided on the outer peripheral side of the first metal shield 31.

  The sensor unit 13 and each member covering the sensor unit 13 may be provided on the back surface 14b of the substrate 14. In this case, the back surface 14b of the substrate 14 is one surface and the front surface 14a is the other surface.

10 Radiation Detection Device 13 Sensor Unit 14 Printed Circuit Board (Board)
14a Surface (one side)
14b Back side (the other side)
14c hole 18 metal shield (second shield)
25 radiation detector 26 amplifier circuit 28 sensor metal shield 31 first metal shield 31b side surface 32 second metal shield 35 magnetic shield 38 radio wave absorbing sheet

Claims (10)

A sensor unit mounted on one surface of a predetermined substrate for detecting radiation;
A radiation detection apparatus comprising: a metal shield body that covers both surfaces of the substrate and accommodates the sensor unit therein.   2. The radiation detection apparatus according to claim 1, wherein a plurality of holes are formed in the substrate, and the metal shield bodies located on both surfaces of the substrate are connected to each other by a conductor provided in the hole. . The metal shield body is provided on one surface of the substrate and covers the sensor unit;
A second metal shield provided on the other surface of the substrate and covering a region corresponding to the mounting portion of the sensor unit;
The radiation detection apparatus according to claim 1, wherein the first metal shield and the second metal shield are provided separately.   The radiation detection apparatus according to claim 3, wherein a plurality of holes are formed in the substrate, and the first metal shield and the second metal shield are connected by a conductor provided in the hole.   The radiation detection apparatus according to claim 3, wherein a magnetic shield body that covers the first metal shield is provided.   The radiation detection apparatus according to claim 3, wherein an electromagnetic wave absorbing sheet is provided on an outer peripheral side of the first metal shield.   The radiation detection apparatus according to claim 3, wherein a magnetic shield body that covers the first metal shield is provided, and an electromagnetic wave absorbing sheet is provided outside the magnetic shield body.   The said 1st metal shield is provided with the side part extended in the thickness direction of the said board | substrate, and the said electromagnetic wave absorption sheet is provided in the position which surrounds the said side part. Radiation detection equipment.   The radiation detection apparatus according to claim 1, wherein the sensor unit includes a radiation detection element and a sensor metal shield that covers the radiation detection element.   The radiation detection apparatus according to claim 9, wherein the sensor unit includes an amplification circuit that amplifies a radiation detection signal from the radiation detection element inside the sensor metal shield.

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