JP4995761B2 - Radiation-resistant head separation type imaging device - Google Patents

Description

The present invention relates to an improvement of a radiation-resistant head separation type imaging apparatus used in a radiation irradiation atmosphere.

For example, Japanese Patent Application Laid-Open No. 07-248396 is known as a radiation-resistant imaging device used in a conventional radiation irradiation atmosphere. (See Patent Document 1)

The above invention is a housing type camera constituted by an outer case provided with a radiation shielding member and a removable inner case provided with an image pickup device, and incident light is introduced by an optical optical path changing means. The radiation shielding member has a front wall portion thicker than a side wall portion. Further, the angle of the optical optical path changing means can be adjusted. In the present invention, when the radiation direction of radiation can be specified, the imaging element is protected by the minimum necessary radiation shielding member, so that the camera can be reduced in size and weight. Further, since the optical path changing means can be adjusted, it is possible in some cases to capture an image of an arbitrary subject without changing the direction of the camera.

Japanese Patent Laid-Open No. 04-188098 is known as a radiation-resistant imaging device that assumes that radiation is emitted from all directions. (See Patent Document 2)

The above invention has a flask-type shield, and a CCD camera is arranged in the internal cavity to shield the CCD against radiation from all directions.
JP 07-248396 A JP 04-188098 A

However, in the invention of Patent Document 1, when the radiation direction of radiation cannot be specified, there is a case where an imaging element having a low radiation resistance cannot be sufficiently shielded. Further, in the invention of Patent Document 2, in order to cope with radiation irradiation from all directions, the shield becomes thick in all directions, and the camera becomes heavy and large.

The object of the present invention is to provide sufficient radiation shielding for the image sensor, assuming that the radiation is emitted from all directions, and to reduce the weight and size of the camera head and to make the structure of the subject itself complicated. It is an object of the present invention to provide a radiation-resistant head-separated imaging device that suppresses an increase in cost without impairing the operability of the camera even when the spatial constraints such as use in a narrow space are large.

The radiation-resistant head-separated imaging device according to the present invention includes a camera head unit having a function of outputting a video signal from an imaging device and a signal processing unit for processing the video signal, which are used in a radiation irradiation atmosphere. A radiation-resistant head-separated imaging apparatus with a separated control unit, wherein the camera head is composed of a cylindrical outer casing, and the tip of the outer casing is optically offset from the central axis of the cylindrical body. A light incident portion made of an optical member is provided, and in the storage space formed inside the outer casing, the optical path of incident light incident from the light incident portion substantially parallel to the central axis of the cylindrical body is the center of the cylindrical body. and optical means for changing toward the axis, been disposed an image sensor for receiving incident light that is changing the optical path by the optical means, wherein the storage space is covered with the exception of the light incident portion in the wall surface of the shielding member The imaging element Is mounted on the card ridge Shikinaiko, characterized in that the cartridge Shikinaiko is detachably inserted from the rear end surface of the outer housing in the vicinity of the center axis of the cylindrical body of the storage space.

A second problem-solving means relates to a radiation-resistant head-separated imaging device, wherein the radiation shielding member has a wall surface opposite to the imaging surface and the back surface of the imaging device that is thicker than the other wall surfaces. is there.

According to the present invention, it is assumed that radiation is emitted from all directions, and sufficient radiation shielding is performed on the imaging device, and the camera head unit can be reduced in weight and size. It is possible to provide a radiation-resistant head-separated imaging apparatus capable of suppressing an increase in cost without impairing the operability of the camera even in a complicated case or when there are large spatial restrictions such as use in a narrow space.

  The Example of this invention is shown.

FIG. 1 is a conceptual diagram showing an embodiment of the present invention. The embodiment is a radiation-resistant head-separated imaging device 19 including a camera head unit 13, a camera control unit unit 16, and a camera cable 11 connecting them.

A sectional view of this embodiment is shown in FIG. 2 is a cross-sectional view taken along the line XX in FIG. 1, and Y in FIGS. 1 and 2 indicates an optical path of incident light. The light incident through the cover glass 1 which is an optical member is refracted by the lens 2a, then the optical path is changed by about 90 degrees by the optical path changing means 3, refracted by the lens 2b again, and then a removable cartridge type core. 10 enters the image pickup surface 17 of the image pickup device 4 in the image pickup device 4. As the image sensor 4, a CCD, CMOS, or other available element can be used as appropriate. Further, as the optical path changing means 3, a mirror, a prism or the like can be used, and the lenses 2a and 2b can be radiation-resistant non-browning lenses.

In this embodiment, the light incident through the cover glass 1 which is an optical member is refracted by the lens 2a, and then the optical path is changed by approximately 90 degrees by the optical optical path changing means 3, but the shape of the camera head part, An appropriate optical path change angle can be taken depending on the size and the like.

In this embodiment, the optical path is changed once. However, the optical path can be changed a plurality of times depending on the shape and size of the camera head. In addition, when the optical path is changed an odd number of times, the camera control unit 16 can be provided with means for electrically inverting the image from the image sensor 14 for convenience of use.

A head-separated type in which a camera head unit having a function of outputting a video signal from an image sensor and a camera control unit unit having a signal processing unit for processing the video signal, which are features of the present embodiment, will be described. The camera head unit 13 is composed of only the image sensor 4 and the minimum necessary image sensor peripheral circuit 9, and other circuits such as a signal processing circuit and an image sensor drive circuit are stored in the camera control unit 16. These circuit components are not exposed to radiation. This makes it possible to reduce the size and weight of the camera head unit 13 without compromising the operability of the camera even when the structure of the subject itself is complex or when there are large spatial constraints such as use in a narrow space. In addition, the replacement frequency of the camera head unit 13 can be reduced and the cost increase can be suppressed.

In this embodiment, the light incident portion 14 on which light is incident is disposed at a position eccentric with respect to the camera head center 18, and the optical path of the incident light is approximately 90 degrees toward the central portion by the optical optical path changing means 3. Therefore, the image pickup surface of the image pickup element 4 faces the direction perpendicular to the incident light. In the present embodiment, as shown in a range C of direct light from the light incident portion in FIG. 3, the imaging element is placed at a position where radiation does not directly enter the imaging surface 17 and the back surface of the imaging element 4 without passing through the radiation shielding member 5. It is arranged. An imaging device such as an imaging device has a significantly inferior radiation resistance on the imaging surface, so that the radiation resistance of the imaging device is improved by avoiding direct irradiation of radiation onto the imaging surface. Further, the opposing wall surface on the back side of the imaging surface of the imaging element 4 is covered with the radiation shielding member 5.

The radiation shielding member that is a feature of the present embodiment will be described. For example, a CCD will be described as an example of a typical imaging device. In a CCD, light incident on the surface of a silicon substrate is converted into electric charges (photoelectric conversion), and the electric charges are transferred by a change in electrical potential on the surface of the silicon substrate. Since it is a surface element, it is important to minimize radiation exposure on the surface of the silicon substrate that performs photoelectric conversion and charge transfer. The same applies to image sensors other than CCDs. In this embodiment, the radiation shielding member 5 on the imaging surface 17 and the back surface of the imaging device 4 is thicker than the other part (thickness A in FIG. 2), and the radiation shielding member 5 in the other part is not thickened (see FIG. 2. Thickness B), efficiently shields radiation.

The degree of damage of radiation to the image sensor is maximum when the image sensor is irradiated perpendicularly to the image pickup surface, and is minimal when the image sensor is irradiated sideways, that is, horizontally. Since radiation irradiation from all directions is assumed to be uniform, it is assumed as an average value that it is incident on the imaging surface at 45 degrees. In this embodiment, for example, as shown in FIG. 4, assuming a radiation Z incident at an angle of 45 degrees with respect to the imaging surface 17 of the imaging device 4, the radiation shielding member 5 through which the radiation Z passes before reaching the imaging surface 17. The effective thickness of the radiation shielding is B × √2. The example shown in FIG. 4 is an example in which radiation is shielded most effectively. However, the degree of damage to an image sensor can be reduced by shielding radiation that is directly irradiated even if only a part is shielded.

The cartridge type inner core 10 which is a feature of the present embodiment will be described. Since the image pickup device 4 is disposed on the replaceable cartridge type core 10, when the life of the image pickup device 4 is shortened due to radiation, only the cartridge type core 10 is replaced. The radiation shielding member 5 and precision optical components such as the cover glass 1, the lenses 2a and 2b, the optical optical path changing means 3 and the like form an outer casing 12, and can be used repeatedly.

The feature of this embodiment and the fact that the radiation shielding member contains a rare heavy metal will be described. Conventionally, lead has been widely used for the radiation shielding member 5, but it is also possible to use rare heavy metals such as tungsten, molybdenum, and bismuth as the main component of the radiation shielding member 5 in consideration of environmental effects. Rare heavy metals such as tungsten, molybdenum, and bismuth are generally effective, but the present invention can suppress an increase in cost.

Since rare heavy metals such as tungsten, molybdenum, and bismuth are relatively inferior in brittleness, in this embodiment, in order to improve the brittleness of the camera head portion 13, the outside of the radiation shielding member 5 is relatively brittle, workable, and corrosion resistant. It is covered with an excellent metal outer shell 20. The metal outer shell 20 can be made of metal such as stainless steel, which is relatively excellent in brittleness, workability, and corrosion resistance.

In this embodiment, the cover glass 1 and the outer casing 12 on which light enters and the cartridge-type inner core 10 and the outer casing 12 are engaged by the O-ring 7 or the like so that the camera head unit 13 can be used in water. It has a sealed waterproof structure that can be used as an underwater camera for nuclear reactor inspection. In this embodiment, since the head separation type is adopted, the camera head unit 13 is composed of the image sensor 4 and the minimum necessary image sensor peripheral circuit 9, and a signal processing circuit and an image sensor driving device that generate a large amount of heat. Since the circuit such as a circuit is arranged in the camera control unit 16, even if the camera head unit 13 is sealed and waterproofed for waterproofing, the temperature rise of the camera head unit 13 is slight, and the camera operation malfunctions due to the temperature rise. Does not occur. Moreover, since the brittleness of the camera head part 13 is improved by the metal outer shell 20 having excellent brittleness, workability and corrosion resistance, the durability of the sealed waterproof structure is excellent.

In the present embodiment, it is also assumed that the camera cable 11 for connecting the camera head unit 13 and the camera control unit unit 16 is 30 m or longer, assuming that it is used for remote visual inspection of the reactor internal structure. The cable length can be appropriately adopted.

Further, in this embodiment, the efficiency of the radiation shielding structure increases the size and weight of the camera head unit 13 and increases the potentially usable internal space of the camera head unit 13. The remote focus lens driving means 9 is disposed in the camera head unit 13.

Further, in this embodiment, the efficiency of the radiation shielding structure reduces the size and weight of the camera head unit 13 and increases the potentially usable internal space of the camera head unit 13, so that illumination means is arranged on the camera head unit 13. Is possible. As the illuminating means, a light emitting diode having excellent radiation resistance can be used. For the same reason, an aiming instruction function for a subject, for example, a laser marker or the like can be arranged in the camera head unit 13.

The shape from the front of the camera head unit 13 can be a shape that optimizes the efficiency of the radiation shielding structure according to the internal structure of the camera head unit 13, for example, an ellipse, an oval, or a circle.

INDUSTRIAL APPLICABILITY The present invention can be used as an imaging device for visual inspection having excellent radiation resistance at a nuclear power plant or the like.

It is an external view of this invention Example. It is sectional drawing of the camera head part side surface of an Example of this invention. It is sectional drawing of the camera head part side surface which shows the arrangement | positioning relationship between the image pick-up element of this invention Example, and a light-incidence part. It is a figure which shows the optical path of the radiation which injects with an angle of 45 degree | times with respect to the imaging surface of the image pick-up element of an Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, Cover glass 2a, 2b Lens 3, Optical optical path changing means 4, Imaging element 5, 15 Radiation shielding member 6, Flange 7a, 7b O-ring 8, Remote focus lens drive means 9, Imaging element peripheral circuit 10, Cartridge Expression core 11, camera cable 12, outer housing 13, camera head unit 14, light incident unit 16, camera control unit unit 17, image sensor imaging surface 18, camera head center unit 19, radiation-resistant head separation type imaging device 20, Metal outer shell A, thickness B of the radiation shielding member facing the imaging device imaging surface and the back surface, thickness C of the radiation shielding member where the imaging device imaging surface and the back surface are not facing, direct light from the light incident part X-X exposure range, section line Y in cross-sectional view 2, optical path Z of incident light, optical path of radiation incident at 45 degrees

Claims (2)

A radiation-resistant head-separated imaging apparatus separated from a camera head unit having a function of outputting a video signal from an imaging device and a camera control unit unit having a signal processing unit for processing the video signal, which is used in a radiation irradiation atmosphere There,
The camera head portion is composed of a cylindrical outer casing, and a light incident portion made of an optical member is provided at a position deviated from the central axis of the cylindrical body on the front end surface of the outer casing, and optical means for the formed storage space to change toward the optical path of the incident light that is substantially parallel to the incident with the center axis of the cylinder from the light incident portion to the central axis of the cylindrical body, the optical path by said optical means And an image sensor that receives the changed incident light ,
The storage space is covered with a wall surface of a radiation shielding member except for a light incident portion, and the image pickup element is mounted on a cartridge type inner core, and the cartridge type inner core is formed from a rear end surface of an outer casing of the cylindrical body of the storage space. A radiation-resistant head-separated imaging device, wherein the imaging device is detachably inserted near a central axis . The shielding member in a radioactive head separated imaging apparatus according to claim 1 Symbol mounting, characterized in that the imaging surface and the back surface is opposite walls wall thickness than other wall surface of the imaging element.