JP2016114635A - Camera housing and image capturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure acquisition of clear images even through prolonged continuous use by preventing dust, floating fluff, and mist from being attracted to a camera lens.SOLUTION: A camera housing 1 comprises a front face located at a position opposite a surface of a camera lens 5 provided therein, a back face located at a position opposite the front face, and other side faces, where an opening 2 is provided through the front face and an air exhaust port 3 is provided on the back face and/or on the side face(s). A diameter of an inscribed circle of the opening 2 is no more than 0.9 times a diameter of an inscribed circle of the front face, and the area of the air exhaust port 3 is not less than 0.1 times the area of the opening 2.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a camera housing that prevents dust, floating fluff, and mist from adhering to a camera lens in an environment where dust, floating fluff, and mist are generated.

  In recent years, camera devices such as video cameras have been used for various purposes. For example, they are used for various purposes such as those used for monitoring purposes not only for home use but also for business use, and those used for recording and observation purposes at production sites. And since there are places where the camera device used for the above purpose is difficult to access, such as high places, narrow places, or places that adversely affect the human body, once installed camera devices are maintenance-free. It is desirable. On the other hand, in places such as those described above, there are many places where dust, floating fluff, mist, and the like are scattered, and it is necessary to protect the camera device using a dustproof camera housing.

  For this reason, as a conventional dustproof camera housing, for example, an opening is provided in the front of the camera lens and an air discharge port is provided at the rear of the camera on the wall of the camera housing, and the air discharged from the air discharge port is passed through the opening from the camera housing. There is known one that prevents dust and the like from adhering to a camera lens by discharging outward (Patent Document 1).

  A camera housing provided with a transparent partition plate in front of the camera lens; air configured to run from the periphery along the partition plate surface toward the center in front of the partition plate; and toward the partition plate. There is also known one provided with air configured to blow off dust or the like (Patent Document 2).

  Further, there is also known a device in which a transparent partition plate is provided on the front surface of the camera lens, and dust and mist adhering to the front surface of the transparent plate are cleaned with a device such as a wiper (Patent Document 3).

JP-A-6-167760 JP 2001-108880 A JP 2006-235061 A

  However, in the technique of Patent Document 1, the camera device vibrates due to the flow velocity of the discharge air from the air discharge port provided behind the camera on the wall surface of the camera housing, and the image captured by the camera device is blurred. . On the other hand, if the flow rate of the discharge air is reduced to prevent the camera device from vibrating, the flow rate of the air discharged from the opening to the outside of the camera housing is reduced, and scattered dust and mist flow into the housing. There is a problem that not only cannot a clear image be secured on the lens surface, but also the camera device may break down due to mist mixed inside the lens or the camera.

  Furthermore, if the air discharge port provided at the rear of the camera on the wall surface of the camera housing is provided at a position that does not directly contact the camera device, the discharge speed at the opening will be biased, and the pressure will be low at the part where the discharge flow rate is fast, There is also a problem that dust or mist outside the camera housing enters the portion and flows into the camera housing.

  In the technique of Patent Document 2, air that is configured to run from the periphery along the partition plate wall surface and toward the center in front of the partition plate is formed to flow forward to the partition plate front. As the flow velocity decreases, the air that collides on the optical axis of the camera lens generates air that moves away from the front side of the partition plate to the front side and air that returns to the rear side. There is a problem that the mist is caught and adhered to the partition plate, so that a clear image cannot be secured, and the partition plate needs to be periodically cleaned.

  In the technique of Patent Document 3, if the wiper is operated in a state where dust or mist is adhered to the transparent plate, the transparent plate becomes dirty or the wiper must be periodically replaced. There was a problem to do.

  As described above, in a conventional camera housing, dust, floating fluff, and mist adhere to the camera lens or transparent partition plate in an environment where dust, floating fluff, and mist are generated, and a clear image cannot be secured. There was a problem. Therefore, an object of the present invention is to provide a camera housing that can ensure a clear image even when used continuously without dust, floating fluff, and mist adhering to the camera lens. .

  In order to solve the above problems, a camera housing of the present invention includes a front surface portion provided at a position facing a lens surface of a camera lens provided therein, a rear surface portion provided at a position facing the front surface portion, and other side surfaces. A camera housing having an opening on the front surface and an air discharge port on the rear surface and / or side surface, the diameter of the inscribed circle on the front surface The diameter is 0.9 times or less, and the area of the air discharge port is 0.1 times or more with respect to the area of the opening.

  The imaging method of the present invention is an imaging method for imaging using a camera device provided inside the camera housing.

  With the camera housing of the present invention, even in an environment where dust, floating fluff, and mist are generated, it becomes possible to continuously ensure a clear image by the camera without dust, floating fluff, and mist adhering to the camera lens. .

FIG. 1 is a cross-sectional view showing a schematic configuration of a camera housing according to the first embodiment of the present invention. FIG. 2 is a front view of FIG. FIG. 3 is a sectional view showing a schematic structure of a camera housing according to the second embodiment of the present invention. 4 is a cross-sectional view taken along line AA in FIG. FIG. 5 is a sectional view showing a schematic structure of a camera housing in the third embodiment of the present invention. FIG. 6 is a diagram illustrating a form in which evaluation is performed in Example 1. FIG. FIG. 7 is a discharge velocity distribution diagram in the opening of Example 1 (1-a). FIG. 8 is a distribution diagram of the discharge speed at the opening of the third embodiment. FIG. 9 is a distribution diagram of the discharge speed in the opening of the comparative example (E).

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

<First Embodiment of the Present Invention>
1 and 2 relate to an embodiment of the present invention, and FIG. 1 is a cross-sectional view showing a schematic internal structure of a camera device and the like including a camera housing 1 and a camera 4 and a camera lens 5 provided in the camera housing 1. FIG. 2 is a front view of FIG.

  As shown in FIG. 1, the camera housing 1 of the present invention includes a front surface portion provided at a position facing the lens surface of a camera lens 5 provided therein, a rear surface portion provided at a position facing the front surface portion, and other parts. The camera housing 1 has an opening 2 in the front surface portion, and includes an air outlet 3 in the rear surface portion and / or the side surface portion of the camera housing 1. The “camera housing” is a case for protecting the entire camera device provided inside from dust, floating fluff, mist and the like scattered around.

  The opening 2 is provided on the front surface of the camera housing 1. A surface including the front surface portion and the opening 2 of the camera housing 1 is referred to as an “opening surface”. Furthermore, as shown in FIG. 1, in the present invention, the thickness of the opening 2 is the same as the thickness of the member on the front surface of the camera housing 1.

  Here, the shape of the camera housing 1 as viewed from the front side is preferably an axisymmetric shape with respect to the optical axis 7 as shown in FIG. In order for the air 3b discharged from the opening 2 to the outside of the camera housing 1 to be uniform in the discharge speed in the opening 2 and to form uniform discharge air, the flow path inside the camera housing 1 is also related to the optical axis 7. It is because it is preferable that it is an axis object. Here, as shown in FIG. 1, the optical axis 7 is a straight line passing through the center of the camera lens 5, and is the same as the rotational symmetry axis of the camera lens 5.

  Here, the dimensions of the camera housing 1, the opening 2, and the air discharge port 3 satisfy the following relationship. That is, the diameter of the inscribed circle of the opening 2 is 0.9 times or less than the diameter of the inscribed circle of the front surface of the camera housing 1, and the area of the air discharge port is 0.1 times the area of the opening. It is more than double.

  Since the flow rate of the air 3a discharged from the air discharge port 3 to the camera housing 1 and the flow rate of the discharge air 3b discharged from the opening 2 to the outside of the camera housing 1 are equal, if the area of the opening 2 is increased, the opening The flow velocity of the discharge air 3b in the part 2 is reduced, and dust, floating fluff, and mist scattered outside the camera housing 1 may enter the camera housing 1 from the opening 2 in some cases.

  Therefore, the relationship between the opening 2 and the camera housing 1 is as follows. As shown in FIG. 2, when the diameter of the inscribed circle of the opening 2 is D and the diameter of the inscribed circle of the front surface is L, the opening 2 The range in which uniform discharge air 3b without dust, floating fluff, and mist flowing outside the camera housing 1 can be obtained is D / L = 0.9 or less.

  Here, in the case of the camera lens 5 that is axisymmetric with respect to the optical axis 7, the shape of the opening 2 is most preferably a circle centered on the same optical axis 7 as the region 14 that forms the angle of view. . The “region formed by the angle of view” is a region of a cross section obtained by cutting a conical region obtained by rotating the side including the angle of view with the focal point 6 as an apex around the optical axis 7 by the two openings. There is a circular range with the optical axis 7 as the center, as shown in FIG.

The relationship between the opening 2 and the air discharge port 3 is that when the area of the opening 2 is S _Out and the area of the air discharge port 3 is S _in , the range in which uniform discharge air can be obtained in the opening 2 is S _in. This is a case where / S _out = 0.1 times or more. If the area of the air discharge port 3 is small and the flow velocity of air that collides with the inner wall surface of the camera device or the camera housing 1 exceeds 10 m / s, the camera device may vibrate, so the air 3a is 10 m / s or less. By increasing the area of the air discharge port 3 as described above, vibration of the camera device can be suppressed while securing the flow rate of the air 3a discharged from the air discharge port 3 to the camera housing 1.

  Therefore, the diameter of the inscribed circle of the opening 2 is less than 0.9 times the diameter of the inscribed circle of the front surface of the camera housing 1, and the rear surface of the camera housing 1 and / or the area of the opening 2 Alternatively, when the area of the air discharge port 3 provided in the side surface portion is 0.1 times or more, dust, floating fluff, and mist scattered outside the camera housing 1 enter the camera housing 1 from the opening 2. And the vibration of the camera device can be suppressed.

  The air discharge port 3 is connected to air generating means such as a pump or a compressor not shown in FIG. 1 through piping or the like. Air 3 a discharged from the air discharge port 3 into the camera housing 1 is discharged from the opening 2 to the outside of the camera housing 1. In the present invention, air having a constant density can be used as “air”.

  As shown in FIG. 1, a camera device including a camera 4 and a camera lens 5 is fixed inside the camera housing 1 via a fixing jig 9, and an image of a subject to be imaged is taken through the opening 2. Further, it is connected to an image display device (not shown) via a cable 10 connected to the camera device, and captures a signal imaged by the imaging device. Here, the cables are a power cable and a camera signal cable. The fixing jig 9 is a member that fixes the camera device and the camera housing. In addition to the embodiment shown in FIG. 1, the fixing jig 9 may be configured to fix the camera device to the rear wall surface of the camera housing.

<Second Embodiment of the Present Invention>
In the second embodiment of the present invention, as shown in FIGS. 3 and 4, instead of the air discharge port 3 being provided in the rear surface portion and / or the side surface portion in the first embodiment of the present invention described above. It is provided over the entire circumference of the side surface of the camera housing 1. Other configurations are the same as those of the first embodiment.

  FIG. 3 is a cross-sectional view showing a schematic internal structure of a camera apparatus and the like including a camera housing 1 and a camera 4 and a camera lens 5 provided in the camera housing 1 according to the second embodiment of the present invention. 4 is a cross-sectional view taken along the line AA in FIG.

  In order to form uniform discharge air with a small difference in discharge speed at the opening 2, a flow is formed inside the camera housing 1 that is parallel to the optical axis 7 and perpendicular to the opening surface including the opening 2. It is preferable. Therefore, by providing the air discharge port 3 on the side surface of the camera housing 1 over the entire side surface, the flow of the discharge air 3b from the air discharge port 3 targeted for the optical axis 7 is kept constant. Compared with the case where the air discharge port 3 is provided on the rear surface portion and / or the side surface portion of the camera housing 1 as in the first embodiment of the present invention described above, more uniform discharge air can be formed. can do. Here, the “entire circumference” only needs to be provided substantially over the entire circumference, and there may be a portion where a hole does not exist partially. Further, by providing the air discharge port 3 on the side surface of the camera housing 1 over the entire side surface, a large area of the air discharge port 3 can be ensured, so that even if the flow rate is increased, camera vibration is prevented. be able to.

As the air discharge port 3, for example, a slit-like one provided over the entire circumference of the side surface of the camera housing 1 can be preferably employed. In the embodiment of the present invention, the slit width is preferably 2 mm or more under the condition that the flow rate of the air discharge port is 0.008 m ³ / min. Uniform discharge air with a smaller speed difference can be formed. When the width of the slit exceeds 18 mm, the strength of the camera housing may decrease.

<Third Embodiment of the Present Invention>
The third embodiment of the present invention is characterized in that, in the above-described second embodiment of the present invention, the air discharge port 3 is provided closer to the opening 2 than the lens surface of the camera lens 5.

  When the air discharge port 3 is provided on the rear side of the lens surface of the camera lens 5 or when the air discharge port 3b from the air discharge port 3 hits the side surface of the camera lens 5, the camera device and the fixed Depending on the shape and material of the jig 9 and the mounting position, a flow velocity difference may occur in the discharge air 3 b in the region of the opening 2. For example, the flow velocity of the discharge air 3b is large near the center of the opening 2, and the flow velocity may decrease as the distance from the center increases in the radial direction. Even if a flow to be discharged to the outside of the camera housing 1 is formed within the range of the opening 2, if there is a large difference in the flow velocity to be discharged, a vortex is generated in a portion where the discharge flow velocity is large, and a portion where the discharge flow velocity is low A flow field that flows into the camera housing 1 may occur. Therefore, in the range of the opening 2, it is preferable that a flow to be discharged to the outside of the camera housing 1 is formed and the difference in discharge flow velocity is small. Here, the “side surface of the camera lens 5” indicates a portion of the camera lens having a zoom ring or a focus ring.

  On the other hand, by setting the position of the air discharge port 3 closer to the opening 2 than the lens surface of the camera lens 5, the shape and material of the camera device and the fixing jig 9 and the mounting position are affected. Therefore, more uniform discharge air 3b can be formed in the opening 2.

  Further, the air discharge port 3 is provided on the side surface of the camera housing 1 at a position where the discharge air 3 a from the air discharge port 3 flows toward the optical axis 7 along the lens surface of the camera lens 5. The most uniform discharge air 3b can be formed. In order to form uniform discharge air 3 b in the opening 2, it is preferable that the flow is parallel to the optical axis 7 and proceeds at right angles to the opening 2. For that purpose, by separating the distance between the opening 2 and the surface on which the air discharge port 3 is provided, by ensuring a long run-up distance so that a flow that proceeds perpendicularly from the air discharge port 3 to the opening 2 is formed, This is because uniform discharge air 3b can be obtained at the opening 2.

  The operation of the camera housing 1 configured as described above will be described.

  As shown in FIG. 5, air 3 a discharged into the camera housing 1 from the air discharge port 3 provided over the entire circumference of the side surface of the camera housing 1 is directed to the optical axis 7 along the lens surface of the camera lens 4. Air travels on the optical axis 7 and collides. Thereafter, a flow is formed that proceeds in the direction toward the front surface of the camera housing 1 and toward the rear surface. Here, the flow proceeding in the direction of the front surface of the camera housing 1 is a flow orthogonal to the surface having the opening 2 and is discharged from the opening 2 to the outside of the camera housing 1 to form air 3b. On the other hand, the flow proceeding to the rear surface portion of the camera housing 1 is a flow proceeding again toward the front surface portion of the camera housing 1 by colliding with the lens surface of the camera lens 4. As a result, the discharge air 3b is efficiently formed, and a flow from the opening 2 to the outside is formed at both the center and the end of the opening 2, and dust, floating fluff outside the camera housing 1, It is possible to prevent mist from flowing into the inside of the camera housing 1 from the opening 2 and sticking to the camera lens 5, and a clear image can be ensured even if it is continuously used.

  A camera device used for outdoor monitoring where dust or the like is scattered or recording in a factory where mist or the like is scattered needs to always display a clear image even in a severe environment. In such an environment, conventionally, it has been limited to short-time use, the installation place is limited, and the camera device needs to be periodically cleaned. However, by using the camera device with a camera housing of the present invention, it is possible to always ensure a clear image even under dust, floating fluff, or mist scattering. As a result, the camera device can be installed in a more severe environment that could not be installed if it was a camera device for monitoring purposes. Further, since the recording camera device in the factory does not require periodic maintenance, it is possible to always record and inspect as a clear image without losing a product produced continuously.

  Regarding the camera housing of the present invention, the velocity distribution of the discharge air at the opening was analyzed and its effectiveness was confirmed. For the analysis, commercially available general-purpose fluid analysis software (“STAR-CCM +” manufactured by C.D. AdaPco) was used.

  An analysis model including the camera housing shown below and a camera and camera lens inside the camera housing was created. The flow field of the fluid was analyzed by dividing the opening into small elements on the analysis model and solving the physical equation with each small element. Here, the “microelement” is called a mesh, a cell, a calculation grid, or the like, and means a tetrahedron or a hexahedron if it is three-dimensional. In addition, “fluid” is a gas, which is air with a constant pressure. The discharge flow velocity was evaluated using a velocity component that proceeds in the direction along the optical axis (z direction).

[Example 1]
As shown in FIG. 1, with respect to the first embodiment of the present invention, the diameter of the inscribed circle of the opening is 0.9 times or more than the diameter of the inscribed circle of the front surface of the camera housing. An example of the analysis of the velocity distribution of the discharge air in the opening of the camera housing in which the area of the air discharge port provided on the wall surface of the camera housing is 0.1 times or more than the area of the portion will be shown. In the range of D / L: 0.50 to 0.83 and S _in / S _out : 0.102 to 0.284, the dimensions of the opening and the air discharge port were changed (1-a), (1-b ) And (1-c) were analyzed under three conditions.

  Table 1 is a table summarizing the camera housing, opening, and air discharge port of the present invention that were analyzed. FIG. 6 is a schematic sectional view of (1-a), (1-b), and (1-c).

  Table 2 is a table summarizing the analysis conditions in detail.

  Table 3 shows the analysis results. The discharge speed at the opening is a positive value along the optical axis in the + z direction and a negative value in the −z direction. If the value is positive, the air is discharged from the inside of the camera housing to the outside. Means that the air flows into the camera housing. As shown in Table 3, it can be seen that no air flows into the camera housing, and the velocity of the air that collides with the camera wall is 10 m / s or less, and there is no camera vibration. It was.

[Example 2]
As shown in FIG. 3, with respect to the second embodiment of the present invention, the velocity distribution of the discharge air at the opening was analyzed for the camera housing in the form in which the side of the camera housing was provided with air discharge ports over the entire side surface. . Except for the shape and position of the air discharge port, this is the same as (1-a) of the first embodiment.

  Table 4 is a table summarizing the camera housing, opening, and air discharge port of the present invention that were analyzed.

  Table 5 is a table summarizing the analysis conditions in detail.

  Table 6 shows the analysis results. As shown in Table 6, there was no generation of air flowing into the camera housing, and the speed of air colliding with the camera wall surface was 10 m / s or less, indicating that there was no camera vibration. Furthermore, compared with Example 1 (1-a), the maximum value of the discharge speed and the minimum value of the discharge speed were increased, and it was found that faster discharge air could be formed.

[Example 3]
As shown in FIG. 5, with respect to the third embodiment of the present invention, a camera having a configuration in which an air discharge port is provided over the entire side of the side surface of the camera housing on the opening side of the lens surface of the camera lens. About the housing, the velocity distribution of the discharge air in an opening part was analyzed. The second embodiment is the same as the second embodiment except for the position of the air discharge port.

  Table 7 is a table summarizing the analysis conditions in detail.

  Table 8 shows the analysis results. As shown in Table 8, there was no generation of air flowing into the camera housing, and the speed of air colliding with the camera wall surface was 10 m / s or less, indicating that there was no camera vibration.

[Comparative example]
As a comparative example, “the diameter of the inscribed circle of the opening is 0.9 times or less than the diameter of the inscribed circle on the front surface of the camera housing, and the air provided on the wall surface of the camera housing with respect to the area of the opening. An example of the analysis of the velocity distribution of the discharge air at the opening of the camera housing that does not satisfy “the area of the discharge port is 0.1 times or more” will be shown.

  Table 7 is a table summarizing in detail the analysis conditions of the camera housing that has been analyzed.

  Table 10 shows the analysis results. As a result, as shown in (A), (C), and (E), in the camera housing in which the diameter of the inscribed circle of the opening exceeds 0.9 with respect to the diameter of the inscribed circle of the front surface of the camera housing, It was found that there was a flow flowing into the interior. Also, as shown in (B) and (D), in the camera housing in which the area of the air discharge port is less than 0.1 relative to the area of the opening, air colliding with the rear part of the camera at about 40 m / s is generated. Therefore, it was found that camera vibrations occurred.

  Table 11 shows a summary of Examples 1 to 3 and Comparative Examples. The results of four-level evaluation of A, B, C, and D in descending order of performance are shown in the table. Here, the minimum value of the discharge speed, the standard deviation of the discharge speed, and the maximum value of the discharge speed are respectively ranked, and D which does not satisfy the performance such as inflow of mist from the opening or vibration of the camera device is designated as D. did. In addition, in Example 1, in order to make a comparison under the same conditions, the diameter of the inscribed circle of the opening and the area of the air discharge port are substantially the same as in Example 2 and Example 3 (1-a). A comparison was made.

  From this result, it is confirmed that the camera device does not vibrate due to the discharge air, and that oil mist does not adhere to the surface of the camera lens even during long-term use, and that a clear image can be secured as it is immediately after the camera device is installed. It was.

  FIG. 7 shows the velocity distribution at the opening of Example 1 (1-a), FIG. 8 shows the velocity distribution at the opening of Example 3, and FIG. 9 shows the velocity distribution at the opening of Example 3. In either case, the flow velocity at the opening is indicated by the shading of the image, and the whiter the flow velocity, the greater the flow velocity. Further, in order to shorten the analysis time, only one half of the circular opening is analyzed, and the boundary that forms the diameter of the opening is a symmetric boundary. It was found that all the results of Example 1 (1-a) and Example 3 had a positive flow velocity distribution. Furthermore, compared with Example 1 (1-a), it turned out that Example 3 has a more uniform flow velocity distribution. In the velocity distribution shown in the comparative example (E), it was found that a negative flow velocity occurred in a part along the circumference of the opening, and there was a flow flowing into the camera housing.

  The present invention can be applied to the prevention of adhesion of dust, floating fluff and mist, but the application range is not limited thereto.

DESCRIPTION OF SYMBOLS 1 Camera housing 2 Opening part 3 Air discharge port 3a Air 3b in discharge port Air in opening part 4 Camera 5 Camera lens 6 Focus 7 Optical axis 8 Angle of view 9 Fixing jig 10 Cable 11 Coordinate system 12 Inscribed circle of camera housing front part 13 Diameter of the inscribed circle at the front of the camera housing 14 Diameter of the inscribed circle at the opening 15 Area formed by the angle of view

Claims (4)

It consists of a front part provided at a position facing the lens surface of the camera lens provided inside, a rear part provided at a position facing the front part, and other side parts, and has an opening on the front part, and a rear part And / or a camera housing having an air outlet on the side surface, wherein the diameter of the inscribed circle of the opening is 0.9 times or less than the diameter of the inscribed circle of the front surface, and the area of the opening On the other hand, a camera housing characterized in that the area of the air discharge port is 0.1 times or more. The camera housing according to claim 1, wherein the air discharge port is provided over the entire circumference of the side surface portion. The camera housing according to claim 1, wherein the air discharge port is provided closer to the opening than the lens surface of the camera lens. The imaging method which images using the camera apparatus with which the inside of the camera housing in any one of Claim 1 to 3 is equipped.

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