JP2013185802A - Lens case and observation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lens case for preventing an adherent which blocks the visual field of a lens.SOLUTION: A lens case (10) includes: a cylindrical casing (20); a lens installation site (22) provided on the inner surface of the casing (20); a flange (24) provided at one end of the casing (20); and an opening (20p) provided at a position between the lens installation site (22) of the casing (20) and the flange. The flange (24) has a body part (24s) and a cutout part (24p) provided on the body part (24s).

Description

  The present invention relates to a lens case and an observation apparatus.

  In order to grasp the internal state of the high temperature furnace, an observation device may be attached to the high temperature furnace. As such an observation apparatus, an observation apparatus that performs imaging through an optical system in which a camera (imaging apparatus) is disposed in a furnace is known (see, for example, Patent Document 1).

  In the observation apparatus of Patent Document 1, the television camera images the inside of the furnace through the lens and glass fiber housed in the middle cylinder. In this observation apparatus, at least a part of the middle cylinder arranged in the furnace is covered with a cooling cylinder, and the cooling water injected from the inlet of the cooling cylinder is circulated through the cooling cylinder and then drained from the drain outlet. Is done. Further, cooling air or nitrogen gas flows into the gap between the middle cylinder and the cooling cylinder from the inlet, and the introduced gas is discharged to the front of the middle cylinder. In the observation apparatus of Patent Document 1, the inner cylinder is cooled by such an inflow of gas.

Japanese Utility Model Publication No. 5-39078

  However, in the observation apparatus disclosed in Patent Document 1, the attached matter that adheres in the field of view of the lens may interfere with the field of view of the lens, and may not be appropriately observed. For example, when an attached material grows on the tip of the middle cylinder housing the lens or the cooling cylinder, the visual field of the lens is obstructed. When the observation apparatus is used at a high temperature, observation cannot be performed appropriately if volatile substances adhere within the field of view of the lens.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a lens case and an observation apparatus suitable for suppressing deposits that obstruct the visual field of the lens.

  The lens case according to the present invention includes a cylindrical housing, a lens installation site provided on the inner surface of the housing, a flange provided at one end of the housing, and the lens installation of the housing. A lens case including an opening provided at a position between the part and the flange, wherein the flange includes a main body and a notch provided in the main body.

  In one embodiment, when the casing is viewed in the length direction of the cylindrical shape of the casing, the opening of the casing is positioned so as to overlap the main body of the flange.

  In one embodiment, the flange has a symmetrical structure when the casing is viewed in the length direction of the cylindrical shape of the casing.

  In one embodiment, when the casing is viewed in the cylindrical length direction of the casing, the openings of the casing are positioned symmetrically.

  In one embodiment, a cross-sectional area of the notch is a smaller one of a minimum cross-sectional area of an inner periphery located on the flange side of the lens installation site of the housing and a total opening area of the opening. 10 times or more.

  An observation apparatus according to the present invention includes a housing cylinder, the lens case housed in the inner periphery of the housing cylinder, a lens installed in the lens installation site of the lens case, the lens case, and the housing cylinder. A gas supply unit that supplies a gas to a path formed between the two, and an imaging device that performs imaging through the lens.

  In one embodiment, the observation device is a lens tube having a pair of end portions, the lens tube having the lens case attached to one end portion of the pair of end portions, and the lens tube. And another lens case attached to the other end.

  ADVANTAGE OF THE INVENTION According to this invention, the lens case and observation apparatus suitable for suppressing the deposit | attachment which obstructs the visual field of a lens can be provided.

(A) is a typical perspective view which shows embodiment of the lens case by this invention, (b) is typical sectional drawing of the lens case shown to (a). (A) is typical sectional drawing of the lens unit which has the lens case shown in FIG. 1, (b) is typical sectional drawing of the observation apparatus of this embodiment. It is typical sectional drawing of the lens holder in the observation apparatus of this embodiment. It is a schematic diagram of the observation apparatus of this embodiment. It is a schematic diagram which shows the observation apparatus of this embodiment attached to the furnace wall. It is a schematic diagram of the lens case of this embodiment in which the lens was installed. It is a schematic diagram of the lens case of this embodiment in which the lens was installed. (A) is a schematic diagram of the lens case of this embodiment, (b) is a schematic sectional view of the lens case shown in (a). It is typical sectional drawing which expanded the front-end | tip part of the lens holder in the observation apparatus of this embodiment. It is typical sectional drawing of the lens case of this embodiment in which the lens was installed. It is typical sectional drawing which expanded the front-end | tip part of the lens holder in the observation apparatus of this embodiment. It is typical sectional drawing of the lens holder in the observation apparatus of this embodiment.

  Embodiments of a lens case and an observation apparatus according to the present invention will be described below with reference to the drawings. However, the present invention is not limited to the following embodiments.

  First, the lens case 10 of this embodiment will be described with reference to FIG. FIG. 1A shows a schematic perspective view of the lens case 10, and FIG. 1B shows a schematic cross-sectional view of the lens case 10. A lens not shown in FIG. 1 is installed in the lens case 10.

  The lens case 10 includes a cylindrical housing 20, a lens installation portion 22 provided on the inner surface of the housing 20, a flange 24 provided on the outer surface of the housing 20, and the lens installation portion 22 and the flange 24. And an opening 20p located therebetween. The flange 24 has a main body 24s and a notch 24p provided in the main body 24s, and the notch 24p has a shape in which a part of the main body 24s is cut.

  The housing 20 is provided with a hole extending in the length direction L. Typically, the housing 20 extends in the length direction L, and the housing 20 has an elongated cylindrical shape. In this case, the longitudinal direction of the housing 20 is equal to the length direction L. Note that the length of the housing 20 along the length direction L is smaller than the outer diameter of the housing 20, and the housing 20 may have a short cylindrical shape. Here, the cross section perpendicular to the length direction L of the housing 20 is substantially annular, and the housing 20 is substantially cylindrical.

  A lens (not shown in FIG. 1) is installed on the inner periphery of the housing 20 by the lens installation site 22. The lens is used for observing an observation object located on the flange 24 side (front) of the housing 20. For example, the lens installation site 22 may be formed by providing a step on the inner surface of the housing 20. Alternatively, the lens installation site 22 may be formed by arranging a predetermined member on the inner periphery of the housing 20.

  As will be described later, a plurality of lenses may be installed in the lens case 10, and a plurality of lens installation sites 22 may be provided on the inner periphery of the housing 20. In this case, the opening 20p is located between the flange 24 and the installation site 22 where the lens located closest to the flange 24 is installed. In this specification, the lens installation site 22 may be simply referred to as the installation site 22.

  The outer surface of the housing 20 communicates with the inner periphery of the housing 20 through the opening 20p. For example, the opening 20p is circular. The opening 20 p is located on the center side of the housing 20 with respect to the length direction L with respect to the flange 24.

  The flange 24 is provided in a partial region of the outer surface of the housing 20 along the circumferential direction. The flange 24 is located on the front side of the lens case 10, and here, the flange 24 is located at one end portion along the length direction L of the housing 20 with respect to the length direction L. When viewed in the length direction L, the main body portion 24s has an annular shape, and the cutout portion 24p has an arc shape whose diameter is smaller than a circle that defines the outer diameter of the main body portion 24s.

  Here, the inner surface of the housing 20 is flat except for the opening 20p and the installation site 22, and the outer surface of the housing 20 is flat except for the opening 20p and the flange 24. The hole diameter of the housing 20 is substantially constant regardless of the position along the length direction L except for the lens installation site 22.

  Here, four cutouts 24p are provided in the main body 24s, and the four cutouts 24p are located at equal intervals. For this reason, when viewed in the length direction L, the flange 24 has point symmetry with respect to a point on the central axis of the substantially cylindrical housing 20 and line symmetry about a line orthogonal to the central axis. have. Thus, it is preferable that the flange 24 has a symmetrical structure. However, the flange 24 does not necessarily have point symmetry and line symmetry, or may have only one of the two symmetries.

  The casing 20 is provided with four openings 20p, and the four openings 20p are arranged at equal intervals in the circumferential direction of the casing 20. Therefore, when viewed in the length direction L, the opening 20p of the housing 20 has a point symmetry with respect to a point on the central axis and a line symmetry with respect to a line orthogonal to the central axis. Is arranged. Thus, it is preferable that the opening part 20p of the housing | casing 20 is arrange | positioned symmetrically. However, the opening 20p of the housing 20 may not necessarily be arranged so as to have point symmetry and line symmetry, or may be arranged so as to have only one of the two symmetries. Good.

  As can be understood from FIG. 1A, here, the notch 24p of the flange 24 is displaced in the circumferential direction with respect to the opening 20p, and when viewed in the length direction L, the opening 20p and The notches 24p are located in different directions, and the opening 20p is located so as to overlap the main body 24s of the flange 24. For this reason, in FIG.1 (b) which shows the cross section of the lens case 10, although the opening part 20p is shown, the notch part 24p is not shown.

  In the lens case 10 of the present embodiment, a portion of the outer surface of the housing 20 corresponding to the lens installation site 22 is continuous with the inner surface of the housing 20 through the opening 20p and is continuous with the notch 24p. ing. As described above, a lens (not shown in FIG. 1) is installed at the installation site 22. Preferably, the lens installed in the lens case 10 is used in combination with other lenses.

  FIG. 2A shows a schematic diagram of a lens unit 50 having the lens case 10 of the present embodiment. The lens unit 50 includes a lens case 10 in which the lens 12 is installed, a lens tube 60, and a lens case 70 in which a lens 72 is installed. The lens 12 is installed at the installation site 22 of the lens case 10.

  The lens case 70 has a cylindrical shape. A lens installation site 74 is provided on the inner surface of the lens case 70, and the lens 72 is installed in the installation site 74 of the lens case 70.

  The lens tube 60 has a cylindrical shape longer than the lens cases 10 and 70. The lens case 10 in which the lens 12 is installed is attached to one end of the lens tube 60, and the lens case 70 in which the lens 72 is installed is attached to the other end of the lens tube 60. For example, the lens cases 10 and 70 are attached to the lens tube 60 using a threaded joint.

  In the lens unit 50 shown in FIG. 2A, the outer diameter of the flange 24 of the lens case 10 is larger than the outer diameters of the lens tube 60 and the lens case 70, respectively. The inner circumferences of the lens case 10, the lens tube 60, and the lens case 70 are continuous. Here, except for the lens installation portions 22 and 74, the inner diameter of the lens case 10 is the same as that of the lens tube 60 and the lens case 70. It is almost equal to the inner diameter of each.

  In the lens unit 50, the lens 12 is used as an objective lens, and the lens 72 is used as an eyepiece. The objective lens 12 is positioned in front of the lens unit 50, and the eyepiece lens 72 is positioned in the rear of the lens unit 50.

  Such a lens unit 50 is suitably used for an observation apparatus.

  FIG. 2B shows a schematic diagram of an embodiment of the observation apparatus 100 according to the present invention. The observation apparatus 100 includes a lens unit 50, a housing cylinder 110, a gas supply unit 120, and an imaging device 130. The housing cylinder 110 has a cylindrical shape, and the lens unit 50 is disposed on the inner periphery of the housing cylinder 110.

  The lens unit 50 is disposed on the inner periphery of the housing cylinder 110 so that the inner surface of the housing cylinder 110 faces the outer surface of the lens unit 50. When the lens unit 50 is disposed on the inner periphery of the housing cylinder 110, a space C is formed between the outer surface of the lens unit 50 and the inner surface of the housing cylinder 110. This space C is used as a gas path. Here, the inner diameter of the housing cylinder 110 is substantially equal to the outer diameter of the flange 24 in the lens case 10 and larger than the outer diameter of the portion other than the flange 24 of the housing 20. Thus, the lens unit 50 is installed integrally with the housing cylinder 110. In this specification, the lens unit 50 and the housing cylinder 110 that are integrally installed may be referred to as a lens holder 150.

  The vent hole Ca communicates with a path C formed between the lens unit 50 and the housing cylinder 110. The path C includes a path C1 formed between the lens case 10 and the housing cylinder 110 and a path C2 formed between the lens tube 60 and the lens case 70 and the housing cylinder 110. C1 and path C2 are continuous. The vent hole Ca communicates with the outside through the opening 20p and the notch 24p located in front of the lens holder 150 via the path C2 and the path C1.

  The gas supply unit 120 is connected to the vent hole Ca. When the gas supply unit 120 feeds gas from the vent hole Ca, the gas travels along the path C in parallel with the length direction L. Air may be used as the gas. In this case, an air curtain can be formed in front of the lens holder 150. Alternatively, nitrogen gas may be used as the gas.

  Part of the gas passes through the opening 20p from the outer surface side of the housing 20 and enters the inner surface side of the housing 20, and then travels along the inner circumference of the housing 20 to the outside through the hole of the housing 20 Sent out. Further, another part of the gas travels on the outer surface side of the housing 20, passes through the notch 24 p of the flange 24, and is sent out in front of the lens case 10. Thus, since the gas sent in from the vent hole Ca is sent to the outside through two paths, the deposits that obstruct the visual field of the lens 12 can be suppressed. In addition, by sending a predetermined amount of gas from the inner periphery of the housing 20 through the opening 20p, the front of the lens 12 becomes negative pressure and volatiles are prevented from being sucked into the front of the lens case 10. it can.

  Here, the inner diameter on the front side of the lens installation site 22 in the housing 20 is constant, but the inner diameter on the front side of the lens installation site 22 in the housing 20 is constant as will be described later. Not necessarily. Further, it is preferable that the amount of gas passing through the notch 24 p is larger than the amount of gas passing through the inner periphery of the housing 20. The amount of gas that passes through the notch 24p is defined by the cross-sectional area of the notch 24p, and the amount of gas that passes through the inner periphery of the housing 20 is that of the inner periphery on the front side of the installation site 22 in the housing 20. It is defined by the smaller of the minimum cross-sectional area and the total opening area of the opening 20p. For this reason, it is preferable that the cross-sectional area of the notch 24p is larger than the smaller one of the minimum cross-sectional area of the inner periphery on the flange 24 side and the total opening area of the opening 20p with respect to the installation site 22 of the housing 20, Moreover, it is preferable that the cross-sectional area of the notch 24p is 10 times or more the smaller one of the minimum cross-sectional area of the inner periphery or the total opening area of the opening 20p.

  For example, the sum of the cross-sectional areas of the four notches 24p is preferably 10 times or more the minimum cross-sectional area of the inner periphery on the flange 24 side with respect to the installation site 22 of the housing 20. Here, the minimum inner diameter on the flange 24 side of the installation site 22 of the housing 20 is equal to the inner diameter of the housing 20, and the cross-sectional area of the notch 24 p is preferably larger than the cross-sectional area of the inner periphery of the housing 20. .

  As described above, the flange 24 has a symmetric structure when viewed in the length direction L (longitudinal direction), and the gas passing through the notch 24p is substantially even with respect to the length direction L. Is sent from. For this reason, the deposit | attachment which obstruct | occludes the visual field of the lens 12 can be suppressed efficiently. Further, when viewed in the length direction L, the opening 20p of the housing 20 is positioned symmetrically, and the gas passing through the opening 20p is delivered from the lens holder 150 almost uniformly with respect to the length direction L. The For this reason, the deposit | attachment which obstruct | occludes the visual field of the lens 12 can be suppressed efficiently.

  In the above description, the four notches 24p are provided in the main body 24s, and the four openings 20p are provided in the housing 20. However, the present invention is not limited to this. Three or less or five or more notches 24p may be provided for the main body 24s, and the housing 20 may be provided with three or less or five or more openings 20p. For example, one notch 24p may be provided for the main body 24s, and one opening 20p may be provided in the housing 20. However, when viewed in the length direction L, the flange 24 preferably has a symmetrical structure, and the opening 20p of the housing 20 is preferably positioned symmetrically.

  In such a lens holder 150, it is preferable that the coolant flows in the housing cylinder 110.

  In FIG. 3, the schematic diagram of the lens holder 150 used for the observation apparatus 100 of this embodiment is shown. Here, when the refrigerant flows in the housing cylinder 110, the temperature rise of the lens 12 is suppressed, and accordingly, the deterioration of the lens 12 can be suppressed.

  The housing cylinder 110 has a cooling pipe 112 that communicates the pipe ports 112a and 112b. For example, the pipe ports 112 a and 112 b are respectively located behind the housing cylinder 110. The cooling pipe 112 extends from the pipe port 112a to the vicinity of the distal end of the housing cylinder 110 in parallel with the length direction L, rotates along the circumferential direction near the distal end, and is parallel to the length direction L from the vicinity of the distal end toward the rear. It extends to the tube port 112b. For this reason, when the refrigerant is injected from the tube port 112a, the refrigerant moves to the vicinity of the front end of the storage cylinder 110, and then rotates in the vicinity of the front end of the storage cylinder 110 along the circumferential direction. It returns to the rear from the vicinity and is discharged from the pipe port 112b. The refrigerant thus circulates around the lens unit 50. The housing cylinder 110 through which the refrigerant circulates is also called a cooling cylinder. For example, the refrigerant is a coolant, and an example thereof is water. Alternatively, the refrigerant may be a gas.

  Further, as described above, a part of the gas passing through the path C passes through the opening 20p from the outer surface side of the housing 20 and enters the inner surface side of the housing 20, and then the inner periphery of the housing 20 And is sent to the outside through a hole in the housing 20. Further, another part of the gas travels on the outer surface side of the housing 20, passes through the notch portion 24 p provided in the main body portion 24 s, and is sent out to the front of the lens case 10. The lens 12 is cooled by transferring the heat of the lens 12 to the refrigerant through the gas. Thus, since the gas sent in from the vent hole Ca is sent to the outside through two paths, the deposits that obstruct the visual field of the lens 12 can be suppressed.

  In FIG. 4, the schematic diagram of the observation apparatus 100 of this embodiment is shown. The observation apparatus 100 illustrated in FIG. 4 includes a support base 132 that supports the imaging apparatus 130. The support table 132 is connected to the housing cylinder 110 and supports the imaging device 130.

  As described above, the objective lens 12 and the eyepiece lens 72 are installed in the lens holder 150, and the imaging device 130 performs imaging through the objective lens 12 and the eyepiece lens 72. The imaging device 130 may include a charge coupled device (CCD) camera, or may be a so-called television camera. In FIG. 4, the configuration of the lens case 10, the housing cylinder 110, and the vent hole Ca is shown in a simplified manner in order to avoid an excessively complicated drawing, and the gas supply unit 120 is shown in FIG. 4. Omitted.

  Such an observation apparatus 100 is preferably used for observing a situation in a furnace having a relatively high temperature. As an example, the observation apparatus 100 is used for observing the inside of a glass melting furnace. The temperature in the glass melting furnace is typically 1500 ° C. or higher. In the observation apparatus 100 of this embodiment, the deposit | attachment which obstruct | occludes the visual field of the lens 12 can be suppressed by sending out gas by two paths | routes in the lens case 10 mentioned above. Moreover, when performing observation in a relatively high temperature furnace, the quality of the lens may be deteriorated due to radiant heat in the furnace. However, in the observation apparatus 100 of the present embodiment, the lens 12 is efficiently cooled, and the lens 12 breakage and deterioration are suppressed.

  In FIG. 5, the schematic diagram of the observation apparatus 100 attached to the furnace is shown. In the observation apparatus 100 illustrated in FIG. 5, a part of the lens holder 150 is installed in an opening provided in the furnace wall, and the imaging apparatus 130 is disposed outside the furnace. Here, the observation apparatus 100 is disposed so as to be inclined with respect to the vertical direction, and the observation apparatus 100 observes the furnace in an oblique direction.

  In the above description, in the lens case 10, the inner surface of the housing 20 is flat except for the opening 20p and the installation site 22, but the present invention is not limited to this. Irregularities may be provided on the inner surface of the housing 20 other than the opening 20p and the installation site 22.

  In FIG. 6, the schematic diagram of the lens case 10 of this embodiment is shown. Here, a lens 12 is installed in the lens case 10. In the lens case 10, the housing 20 has a lens placement portion 20 a, a connection portion 20 b, and an end portion 20 c. The lens arrangement portion 20a, the connection portion 20b, and the end portion 20c are continuously arranged along the length direction L. The end portion 20c is located in front of the lens case 10, and the connection portion 20b is located between the lens placement portion 20a and the end portion 20c. An installation site 22 is provided in the lens placement portion 20 a, and the lens 12 is installed in the installation site 22. Moreover, the opening part 20p is provided in the connection part 20b.

  In addition to the flange 24, a shielding portion 26 is provided at the end 20c of the lens case 10 shown in FIG. The flange 24 has an outer diameter larger than the outer diameter of the lens placement portion 20a. The shielding part 26 is provided with an opening part 26p having a smaller diameter than the inner diameter of the other part of the end part 20c. In addition, the aperture 26p has a smaller diameter than the inner diameter of the other part of the housing 20. By providing the shielding part 26 having the opening 26p having a small diameter on the front side of the installation site 22, heat transfer to the lens 12 can be effectively shielded even when observation is performed at a high temperature. From this viewpoint, it is preferable that the diameter of the opening 26p is as small as possible as long as the field of view of the lens 12 can be secured. In addition, when the aperture 26p has a small diameter, the area of the shield 26 viewed in the length direction L is relatively large. For this reason, the temperature of the shielding part 26 rises to some extent by radiation from a relatively high temperature furnace, and as a result, it is possible to suppress the adhesion of the deposits that obstruct the field of view of the lens 12. For example, the outer diameter of the lens 12 is about 20 mm, and the diameter of the opening 26p is about 5 mm.

  In the above description, the outer surface of the housing 20 is flat except for the opening 20p and the flange 24, but the present invention is not limited to this. Irregularities may be provided on the outer surface of the housing 20 other than the opening 20p and the flange 24.

  FIG. 7 shows a schematic diagram of the lens case 10 of the present embodiment in which the lens 12 is installed. In the lens case 10, the housing 20 has a lens placement portion 20 a, a connection portion 20 b, and an end portion 20 c. An installation site 22 is provided in the lens placement portion 20a.

  Further, the connection portion 20b is provided with an opening 20p. In the lens case 10 shown in FIG. 7, the outer diameter of the connection portion 20b is smaller than the outer diameter of the lens placement portion 20a, and the inner diameter of the connection portion 20b is smaller than the inner diameter of the lens placement portion 20a.

  A flange 24 and a shielding part 26 are provided at the end 20c. In this case as well, the diameter of the opening 26p provided in the shielding part 26 is smaller than the inner diameter of the other part of the housing 20. Moreover, the outer diameter of the connection part 20b of the lens case 10 shown in FIG. 7 is smaller than the outer diameter of the lens arrangement | positioning part 20a. The end portion 20c is provided with a flange 24, and the outer diameter of the flange 24 is larger than the outer diameter of the lens placement portion 20a.

  In addition, here, the shielding portion 26 includes a support portion 26a that is continuous with the flange 24, a protrusion portion 26b that protrudes forward from the support portion 26a along the length direction L, and a center portion that extends radially from the protrusion portion 26b. And a protective portion 26c extending toward the shaft. In this case, the protection part 26c that receives the most radiant heat from the furnace is located relatively far from the lens 12, and thus damage and deterioration of the lens 12 can be suppressed.

  As described above, the notch 24p of the flange 24 is displaced in the circumferential direction with respect to the opening 20p, and when viewed in the length direction L, the opening 20p is positioned so as to overlap the main body 24s. As a result, when the gas moving forward along the length direction L on the outer surface side of the lens case 10 collides with the main body 24s of the flange 24, the gas moves to the inner surface side of the housing 20 and is sent in. Is effectively used. As shown in FIG. 7, when the cross section of the lens case 10 is viewed, the distance along the length direction L between the flange 24 (main body portion 24s) and the opening 20p is preferably relatively short. Thereby, the gas which moves the outer surface side of the lens case 10 forward along the length direction L can be efficiently moved to the inner surface side of the housing 20.

  In the above description, the opening 20p of the housing 20 and the notch 24p of the flange 24 are each four, but the present invention is not limited to this.

  FIG. 8A shows a schematic diagram viewed from the length direction L of the lens case 10 of the present embodiment, and FIG. 8B shows a schematic cross-sectional view of the lens case 10. As shown in FIG. 8A, in the lens case 10, when viewed in the length direction L, the body portion 24s is provided with eight notches 24p. Here, the notches 24p are arranged at equal intervals, and the adjacent notches 24p are arranged so as to be shifted by 45 ° with respect to the central axis of the substantially cylindrical casing 20. Further, when viewed in the length direction L, the notch 24p has a symmetric structure with respect to an axis along the length direction L.

  When viewed in the length direction L, the connection portion 20b is provided with eight openings 20p. Here, the openings 20p are arranged at equal intervals, and the adjacent openings 20p are arranged so as to be shifted by 45 ° with respect to the central axis. When viewed in the length direction L, the opening 20p has a symmetric structure with respect to an axis along the length direction L.

  When viewed in the length direction L, the notch 24p of the main body 24s is positioned so as to be displaced with respect to the opening 20p. Here, when viewed in the length direction L, the notch 24p is displaced by 22.5 ° with respect to the opening 20p.

  Here, the outer diameter of the connection portion 20b is smaller than the outer diameter of the lens arrangement portion 20a, and the inner diameter of the connection portion 20b is smaller than the inner diameter of the lens arrangement portion 20a. The diameter of the opening portion 26p of the end portion 20c is smaller than the inner diameter of the connection portion 20b, and the maximum outer diameter of the flange 24 is larger than the outer diameter of the connection portion 20b. When viewed in the length direction L, the main body portion 24s has an annular shape, and the notch portion 24p has a semicircular shape having a smaller diameter than a circle that defines the outer diameter of the main body portion 24s. Further, as can be understood from FIG. 8B showing a cross section of the lens case 10, a protrusion 24 b protruding forward from the flange 24 is provided at the tip of the flange 24.

  As described above, the amount of gas passing through the notch 24p is preferably larger than the amount of gas passing through the inner periphery of the housing 20, and the amount of gas passing through the inner periphery of the housing 20 is It is defined by the smaller of the minimum cross-sectional area of the inner periphery on the front side of the lens installation site 22 of the body 20 and the total opening area of the opening 20p. Here, the minimum inner diameter of the housing 20 on the front side of the lens installation site 22 is the diameter of the opening 26p, and the sum of the sectional areas of the eight notches 24p is the total opening area and the opening of the opening 26p. It is preferable that the total opening area of 20p is larger than the smaller one. For example, the sum of the cross-sectional areas of the eight notches 24p is 10 times or more the smaller of the total opening area of the opening 26p and the total opening area of the opening 20p. The sum is smaller than the total opening area of the opening 26p, and the ratio of the sum of the total opening areas of the eight notches 24p and the sum of the total opening areas of the eight openings 26p is approximately 15: 1.

  In FIG. 9, the typical cross section which expanded the front-end | tip part of the lens holder 150 in the observation apparatus of this embodiment is shown. The inner surface of the housing cylinder 110 is in contact with the outer surface of the flange 24 provided at the end 20c of the lens case 10, and the gas passing from the path C to the outer surface side of the lens case 10 is shown in FIG. It is sent to the outside through the notch 24p.

  In the above description, one lens 12 is installed as an objective lens on the installation site 22 of the housing 20, but the present invention is not limited to this. The objective lens may be composed of a plurality of lenses.

  FIG. 10 is a schematic cross-sectional view of the lens case 10 of the present embodiment in which the lens 12 is installed. As shown in FIG. 10, the lens case 10 is provided with a plurality of lenses 12. Here, the lens 12 at the front end is installed at an installation site 22 provided at the end of the lens arrangement portion 20a, and the other lens 12 is a lens installation tool 22a designed to match the inner diameter of the housing 20. Is installed on the inner periphery of the casing 20 using the After the front lens is inserted into the inner periphery of the housing 20, the corresponding lens installation tool 22a is inserted into the inner periphery of the housing 20, whereby each lens 12 is installed. For example, the objective lens 12 may be composed of a plurality of lenses having different shapes. Such a lens case 10 is suitably used in combination with the housing cylinder 110 described above.

  FIG. 11 is an enlarged schematic cross-sectional view of the tip portion of the lens holder 150 in the observation apparatus of the present embodiment. Also here, the accommodating cylinder 110 is provided outside the lens case 10, and the gas fed into the path C is not formed in the opening 20 p and the notch 24 p (not shown in FIG. 11, FIG. 8). (See below).

  In the description with reference to FIGS. 10 and 11, the plurality of lenses 12 are installed in the lens case 10, but the present invention is not limited to this. A plurality of lenses 72 may be installed in the lens case 70.

  FIG. 12 shows a schematic cross section of the lens holder 150 in the observation apparatus of the present embodiment. In the lens holder 150 shown in FIG. 12, not only a plurality of lenses 12 are installed in the lens case 10, but also a plurality of lenses 72 are installed in the lens case 70. Thus, not only the objective lens 12 but also the eyepiece lens 72 may be composed of a plurality of lenses.

  In the above description with reference to FIG. 2A and the like, the lens case 10 is attached to one end of the lens tube 60 that is longer than the lens case 10, but the present invention is not limited to this. The lens case 10 itself is relatively long, and the objective lens 12 may be installed at one end and the eyepiece 72 may be installed at the other end.

  In the above description, the lens cases 10 and 70 are attached to both ends of the lens unit 50, but the present invention is not limited to this. The lens case 10 may be attached to one end of the lens unit 50, and the eyepiece may be attached to a member different from the lens unit 50.

  The lens case of this embodiment is suitably used for suppressing deposits that obstruct the field of view of the lens. Such a lens case is suitably used for an observation apparatus that performs observation at high temperatures.

DESCRIPTION OF SYMBOLS 10 Lens case 12 Lens 20 Housing | casing 20p Opening part 22 Lens installation part 24 Flange 24s Main body part 24p Notch part 50 Lens unit 100 Observation apparatus 110 Housing cylinder 120 Gas supply part 130 Imaging apparatus 150 Lens holder

Claims (7)

A cylindrical housing;
A lens installation site provided on the inner surface of the housing;
A flange provided at one end of the housing;
A lens case comprising an opening provided at a position between the lens installation site of the housing and the flange,
The flange includes a main body portion and a cutout portion provided in the main body portion.   2. The lens according to claim 1, wherein the opening of the casing is positioned so as to overlap the main body of the flange when the casing is viewed in the longitudinal direction of the cylindrical shape of the casing. Case.   The lens case according to claim 1, wherein the flange has a symmetric structure when the casing is viewed in a length direction of the cylindrical shape of the casing.   The lens case according to any one of claims 1 to 3, wherein the opening of the casing is positioned symmetrically when the casing is viewed in a length direction of the cylindrical shape of the casing.   The cross-sectional area of the notch is at least 10 times the smaller one of the minimum cross-sectional area of the inner periphery located on the flange side of the lens installation site of the housing and the total opening area of the opening. The lens case according to any one of claims 1 to 4. A container,
The lens case according to any one of claims 1 to 5, housed in an inner periphery of the housing tube,
A lens installed at the lens installation site of the lens case;
A gas supply unit for supplying gas to a path formed between the lens case and the housing cylinder;
An observation apparatus comprising: an imaging apparatus that performs imaging through the lens. A lens tube having a pair of ends, wherein the lens case is attached to one end of the pair of ends; and
The observation apparatus according to claim 6, further comprising: another lens case attached to the other end of the lens tube.

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