Reverse imaging device

Abstract

A backward-facing imaging device (1) for attachment to a movable body, comprising: an imaging unit (3) which captures an image of the back side of the moving body; and a housing (2) that contains the imaging unit (3); wherein the imaging unit (3) comprises a cylindrical shell (6) which holds a transparent element (7, 7a); a recess (2a) is formed in a rear section of the housing (2); and the cylindrical shell (6) penetrates through a bottom (12) of the indentation (2a) and projects rearward from a bottom surface (12a) of the indentation (2a), characterized by the fact that a distance (L2) from an inner surface of the indentation (2a) to an edge of a rear end (6a) of the cylindrical shell (6) is equal to or greater than a projection length (L1) in the cylindrical shell (6).

Description

Technical field

[0001] The present invention relates to a backward-facing imaging device which captures an image of the back of a moving body. Technical background

[0002] Traditionally, mirrors that reflect the rear (including the rear side sides) of a vehicle are located on the sides of the front section of the vehicle, and the vehicle is configured so that the driver can confirm the situation at the rear by looking in the mirrors.

[0003] On the other hand, systems have been studied in recent years that capture an image of the rear of the vehicle by replacing the mirror with an imaging unit and displaying the captured image on a display panel or similar device. According to such systems, the driver can confirm the situation at the rear of the vehicle without having to significantly distract their eyes from the direction ahead.

[0004] JP 2009-241 749 A discloses a rear-facing imaging device equipped with an imaging unit and a housing for accommodating the imaging unit, and which captures an image of the rear of the vehicle.

[0005] In the rear-facing imaging device according to patent document 1, a recess in the form of a cylinder with a base is formed in a rear section of the housing. A lens held in the cylindrical shell of the imaging unit, or a lens filter covering the lens, is arranged at the base of the recess, and the imaging unit captures an image of the rear of the vehicle through the base of the recess. Hereinafter, the lens or lens filter held at a pointed end section of the cylindrical shell is referred to as "the transparent element".

[0006] JP 2011-184030A discloses a backward imaging device having the features of the preamble of claim 1. Summary of the invention: Technical problem

[0007] There is a characteristic that turbulence is likely to occur at the rear of the housing during vehicle movement. Even if the housing has a streamlined shape, a similar characteristic exists.

[0008] Therefore, in a housing with a recess in its rear section, water droplets in contact with the outer circumferential surface of the housing can be trapped in the turbulence and creep into the interior of the recess. Furthermore, if the water droplets in contact with the inner circumferential surface of the recess move towards the bottom surface of the recess, they can come into contact with the transparent element held within the cylindrical shell, so that images of the water droplets can appear in the captured image.

[0009] The present invention was made to solve the above problem, and it is the object of the present invention to provide a reverse imaging device in which the probability of images of water droplets appearing in the captured image is low. Solution to the problem

[0010] The above problem is solved with a backward imaging device having the features of claims 1 and 2.

[0011] The reverse imaging device according to the present invention comprises an imaging unit that captures an image of the rear side of the moving body and a housing that contains the imaging unit. The imaging unit has a cylindrical shell that holds a transparent element, and a recess is formed in a rear section of the housing. The cylindrical shell extends through a bottom section of the recess and projects rearward from a bottom surface of the recess.

[0012] According to the present invention, the transparent element held by the cylindrical shell is separate from the bottom surface of the indentation, and therefore the inner circumferential surface of the indentation does not extend to the transparent element. Consequently, the water droplets moving towards the bottom surface of the indentation come into contact mainly with the outer circumferential surface of the cylindrical shell, and it is unlikely that they will come into contact with the transparent element.

[0013] Furthermore, if the distance (L2) from the inner surface of the indentation to the rear end of the cylinder is less than the projection length (L1) in the cylinder, the water droplets can come into contact with the rear end of the cylinder, even if the diameter of the water droplets moving on the inner surface of the indentation is smaller than the projection length (L1). Conversely, if the distance (L2) from the inner surface of the indentation to the rear end of the cylinder is equal to or greater than the projection length (L1) in the cylinder, the water droplets will not come into contact with the rear end of the cylinder, as long as the diameter of the water droplets moving on the inner surface of the indentation does not exceed the projection length (L1).

[0014] In other words, in one embodiment of the invention, the distance from the inner surface of the indentation to an edge of the rear end of the cylinder shell is equal to or greater than the length of the projection in the cylinder shell. In this case, it is unlikely that water droplets moving on the inner surface of the indentation will come into contact with the rear end of the cylinder shell, and it is further unlikely that they will come into contact with the transparent element.

[0015] The "inner surface" of the indentation means the combined surface area of ​​the inner circumferential surface and the bottom surface of the indentation.

[0016] In another embodiment of the invention, the projection length in the cylindrical shell is greater than the maximum width of the annular area between the rear edge of the outer circumferential surface of the housing and the opening edge of the indentation.

[0017] There is a tendency for the diameters of the water droplets that come into contact with the annular region (that is, the rear surface of the case) between the trailing edge of the outer circumferential surface of the case and the opening edge of the indentation to be less than or equal to the width of the annular region. In other words, the diameters of the water droplets that move towards the inner surface of the indentation along the rear surface of the case tend to be less than or equal to the width of the annular region.

[0018] In the arrangement where the projection length in the cylindrical shell is greater than the maximum width of the aforementioned annular area, even if water droplets reach the bottom surface, the probability that the water droplets will come into contact with the rear end of the cylindrical shell is small, and therefore it is unlikely that the water droplets will come into contact with the transparent element. Advantageous effect of the invention

[0019] As explained above, according to the present invention, it is unlikely that water droplets will come into contact with the transparent element, even if the water droplets move towards the bottom surface of the indentation, and it is unlikely that any influence of the water droplets will be reflected in the image. Brief description of the drawings Fig. Figure 1 is a perspective drawing depicting a vehicle to which a rear-facing imaging device according to one embodiment is attached. Fig. Figure 2 is a rear view of the backward-facing imaging device according to one embodiment. Fig. 3 is a cross-sectional view along the in Fig. 2 shown line AA. Fig. Figure 4 is an enlarged view of a rear section of the reverse imaging device of Fig. 3. Description of the embodiment

[0020] One embodiment of the present invention will be described in detail, with reference to the drawings as needed.

[0021] The explanatory notes on the embodiment include an example case in which the "movable body" is a four-wheeled vehicle (referred to hereafter simply as "the vehicle V"). Furthermore, the front of the vehicle V is referred to as the "front" and the rear of the vehicle V as the "rear". Additionally, the directions "right" and "left" are based on the driver's position.

[0022] As in Fig. 1 and Fig. Figure 2 shows the rear-facing imaging device 1 arranged on the left side of a left door 50 of the vehicle V and attached to a support 51 (see Fig. 2) attached, which extends from the left door 50 to the left. The rear-facing imaging device 1 according to the present embodiment comprises a housing 2, which forms an outer shell of the rear-facing imaging device 1, and an imaging unit 3, which images the rear. A recess 2a is formed in the rear section of the housing 2. The imaging unit 3 is housed in the housing 2 and captures an image of the rear through an opening in the recess 2a. That is, the rear-facing imaging device 1 captures an image of the left rear of the vehicle V from the left side of the left door 50.

[0023] Although not explicitly stated, a similar rear-facing imaging device 1 is arranged on the side of the right door of the vehicle V, such that it is laterally symmetrical to the rear-facing imaging device 1 on the side of the left door. Additionally, although in the example shown in the present embodiment the rear-facing imaging device 1 is arranged on both the right and left doors, the rear-facing imaging device 1 may be arranged at any point on a side.

[0024] As in Fig. As shown in Figure 3, the housing 2 has a space to accommodate the imaging unit 3. The indentation 2a, which extends from a rear surface 2b towards the front, is formed in the rear section of the housing 2.

[0025] The rear surface 2b of the housing 2 is located in the area between the rear edge of an outer circumferential surface 2c of the housing 2 and an opening edge of the recess 2a, and has an annular shape in a rear view. The opening of the recess 2a is formed on the inner side of the rear surface 2b. Rounded (chamfered) surfaces are formed on an outer circumferential edge and on an inner circumferential edge of the rear surface 2b to ensure safety in the event of a collision.

[0026] The outer circumferential surface 2c of the housing 2 has a shape (so-called streamlined shape) such that the occurrence of turbulence near the outer circumferential surface 2c of the housing 2 becomes less likely, since the air resistance (in the front-to-back direction) that occurs during the forward movement of the vehicle V decreases. In the present embodiment, the outer circumferential surface 2c has a paraboloid shape, that is, a shape that tapers towards the front.

[0027] The housing 2 is formed by joining an upper housing element 2d and a lower housing element 2e from above and below, respectively, with the upper housing element 2d being open at the bottom and the lower housing element 2e being open at the top. Furthermore, a mounting receptacle 4 for the imaging unit 3 is formed in the housing 2.

[0028] As in Fig. As shown in Figure 3, a circumferential wall section 11 of the indentation 2a has a shape similar to a spherical band and extends from the inner circumferential edge of the rear surface 2b to the front. In cross-section along a plane to which the optical axis of the imaging unit 3 is perpendicular, the circumferential wall section 11 has the shape of a circle. The diameter of the circumferential wall section 11 decreases gradually towards the front.

[0029] A bottom section 12 of the indentation 2a has the shape of a concave disk, the perpendicular of which runs forwards and backwards. The bottom section 12 includes a section that continues smoothly to the front end of the circumferential wall section 11.

[0030] The recess located in the center of the base section 12 is a through-hole 13 that penetrates the base section 12 in both the forward and backward directions. The cylindrical shell 6 of the imaging unit 3 is inserted through the through-hole 13. The cylindrical shell 6 is a cylindrical element in which an outer circumferential surface with a circular cross-section extends in both the forward and backward directions.

[0031] The through-hole 13 is designed in such a way that it has a shape (circular shape) that is identical to the outer circumferential surface of the cylinder shell 6, so that water droplets do not penetrate into the interior of the housing 2 through a gap between the cylinder shell 6 and the bore wall of the through-hole 13.

[0032] Furthermore, the circumferential wall section 11 and the floor section 12 are arranged radially outside the field of view of a lens 7a (i.e., the maximum extent of the scene imaged by the imaging unit 3). This means that the lens 7a is positioned such that the captured image does not include images of the circumferential wall section 11 and the floor section 12.

[0033] The imaging unit 3 comprises a main part 5, the cylindrical shell 6, and a plurality of lenses 7. The main part 5 is attached to the mounting receptacle 4 in the housing 2. The cylindrical shell 6 extends rearward from the main part 5. The plurality of lenses 7 are housed within the cylindrical shell 6. Fig. 3 and Fig. 4 shows only the rearmost 7a of the lenses 7.)

[0034] Even though, in the present embodiment, the main part 5 is attached to the mounting receptacle 4, the attachment of the imaging unit 3 is not limited to the manner shown. For example, it is possible to provide a pair of ribs inside the housing 2, extending from the top and bottom sides, and to hold the imaging unit 3 with the pair of ribs.

[0035] Main part 5 converts the image of the rear of the vehicle into an electrical signal and includes an image sensor (not shown) that performs a photoelectric conversion of the light from the lenses 7. Main part 5 transmits the captured information (the electrical signal) to a monitor or similar device inside the vehicle V. Thus, the image captured by the imaging unit 3 is displayed on the monitor, and the driver can confirm the situation at the left rear by viewing the monitor.

[0036] The cylindrical shell 6 is a cylindrical element extending in the front-to-back direction and arranged such that it penetrates the base section 12 and is approximately perpendicular to the base surface 12a. The cylindrical shell 6 has a uniform outer diameter along its entire length in both the front and rear directions.

[0037] The lens 7a is held at the rear end 6a of the cylindrical shell 6. The holding of the lens 7a by the cylindrical shell 6 includes the case in which the cylindrical shell 6 holds the lens 7a in contact with the lens 7a, and the case in which another element is inserted between the cylindrical shell 6 and the lens 7a.

[0038] The spherical surface of the lens 7a projects rearward from the rear end 6a of the cylindrical shell 6 and is exposed to the outer surface of the cylindrical shell 6. That is, the outer surface of the lens 7a is located on the rear side of the bottom section 12 of the housing 2 (i.e., on the side closer to the opening of the recess 2a) and faces through the opening of the recess 2a towards the rear of the vehicle.

[0039] Furthermore, the lens 7a is located on the side of the bottom section 12 of the opening edge of the indentation 2a (that is, the rear surface 2b of the housing 2). Therefore, the lens 7a is surrounded by the circumferential wall section 11 of the indentation 2a and is positioned between the opening edge of the indentation 2a and the bottom section 12. Thus, the transparent body, such as the lens 7a or a lens filter, which is located closest to the imaging surface in the imaging unit 3, is positioned in the space formed by the indentation 2a. The imaging unit 3 captures the image of the object through the aforementioned transparent body.

[0040] The lens 7a in the present embodiment corresponds to the “transparent element” mentioned in the appended claims. The viewing angle of the imaging unit 3 (the angle formed by the lens in Fig. The angle between the 3 dashed lines C and C' shown is 90 degrees.

[0041] The relationship between the inner surface of the indentation 2a and the imaging unit 3 is explained in more detail. In the following explanations, one of the outer and inner surfaces of the circumferential wall section 11, which is opposite the indentation 2a (that is, the surface exposed to the outside of the housing 2), is referred to as "the inner circumferential surface 11a", and one of the outer and inner surfaces of the bottom section 12, which is opposite the indentation 2a, is referred to as "the bottom surface 12a".

[0042] As in Fig. As shown in Figure 4, the cylindrical shell 6 in the imaging unit 3 projects rearward from the base surface 12a of the indentation 2a. Therefore, the lens 7a, which is held by the cylindrical shell 6, is separated from the base surface 12a and does not extend to the base surface 12a. Even if water droplets that come into contact with the inner circumferential surface 11a move towards the side of the base surface 12a (as shown by arrows B2 in Figure 4), this does not affect the lens 7a. Fig. 3 shown), therefore the water droplets mainly come into contact with the lateral surface of the cylinder shell 6.

[0043] The projection length L1 in the cylindrical shell 6 is greater than the width L3 of the annular region between the rear edge of the outer circumferential surface 2c of the housing 2 and the opening edge of the indentation 2a. (Hereinafter, the width L3 is referred to as the width of the rear surface 2b.) Additionally, the distance L2 between each position on the inner surface of the indentation 2a (the inner circumferential surface 11a and the bottom surface 12a) and an edge of the rear end 6a of the cylindrical shell 6 gradually increases as the position on the inner surface moves rearward from the side of the bottom section 12. The distance L2 is greater than the width L3 of the rear surface 2b.

[0044] Next, an example of the movement path of water droplets during the movement of the vehicle will be explained.

[0045] When the vehicle V moves in rainy weather, water droplets fly from the front of the rear-facing imaging device 1 and come into contact with the outer circumferential surface 2c of the housing 2. The water droplets on the outer circumferential surface 2c are forced by the airflow to move towards the rear end.

[0046] Most of the water droplets that reach the rear end of the housing 2 are blown towards the back of the housing 2. However, some of the water droplets may be caught by turbulence (vortex) occurring near the rear end of the housing 2 and move along the rear surface 2b to creep towards the inner circumferential surface 11a (as shown by arrows B1 in Fig. (3 shown). The diameters of most of the water droplets that come into contact with the rear surface 2b are less than or equal to the width L3 of the rear surface 2b. Therefore, the diameters of most of the water droplets that come into contact with the inner circumferential surface 11a are also less than or equal to the width L3 of the rear surface 2b.

[0047] Some of the water droplets that come into contact with the inner circumferential surface 11a of the indentation 2a move under the influence of turbulence (vortex) towards the side of the bottom surface 12a (as shown by arrows B2 in Fig. 3 shown). However, since the cylindrical shell 6 protrudes from the base surface 12a, the water droplets moving towards the side of the base surface 12a mainly come into contact with the outer circumferential surface of the cylindrical shell 6.

[0048] As previously explained, the diameters of most of the water droplets moving along the rear surface 2b and coming into contact with the inner circumferential surface 11a are less than or equal to the width L3 of the rear surface 2b. In light of this, according to the present embodiment, the projection length L1 in the cylindrical shell 6 is set greater than the width L3 of the rear surface 2b. Therefore, even if the water droplets reach the bottom surface 12a, the probability of them coming into contact with the lens 7a is small.

[0049] Furthermore, according to the present embodiment, the distance L2 between the inner surface of the indentation 2a and the edge of the rear end 6a of the cylindrical shell 6 is greater than the width L3 of the rear surface 2b. Therefore, the probability that the water droplets will come into contact with the lens 7a during their movement towards the bottom surface 12a is also small.

[0050] Furthermore, while the vehicle is stopped or moving at low speed and the effects of turbulence are small, the water droplets moving towards the side of the bottom surface 12a of the bottom section 12 and the water droplets coming into contact with the outer circumferential surface of the cylinder shell 6 move downwards under the influence of gravity towards the lower side of the cylinder shell 6 (as shown by arrows B3 in Fig. 2 shown), and move further towards the opening of the indentation 2a along the inner circumferential surface 11a on the lower side of the indentation 2a in order to flow out of the opening (as shown by arrow B4 in Fig. 2 shown).

[0051] Furthermore, the cylindrical surface 6 is approximately perpendicular to the base surface 12a, and the outer circumferential surface of the cylindrical surface 6 extends in a horizontal direction. Therefore, even if water droplets come into contact with the outer circumferential surface of the cylindrical surface 6, it is unlikely that the water droplets will flow backwards along the outer circumferential surface of the cylindrical surface 6.

[0052] As explained above, in the backward imaging device 1 according to the embodiment, even if water droplets move from the outer circumferential surface 2c of the housing 2 and are trapped in the indentation 2a, it is unlikely that the water droplets will come into contact with the lens 7a, so that it is unlikely that any influence of the water droplets will be reflected in the image captured by the imaging unit 3.

[0053] Furthermore, lens 7a is located in the imaging unit 3 on the front of the rear surface 2b of the housing 2. In other words, lens 7a is located in a deep position in the recess 2a. In such an arrangement, it is unlikely that rainwater, dirty water splashed by a tire, and the like will come into contact with lens 7a.

[0054] Although the four-wheeled vehicle V is described in the embodiment as an example of the movable body on which the rear-facing imaging device 1 is mounted, it is not intended that the scope of the present invention be limited to this example. For instance, the present invention can be applied to vehicles having fewer than four wheels, and further to other types of vehicles, such as handlebar-mounted vehicles and rail vehicles, and other movable bodies, such as ships, aircraft, and the like.

[0055] Furthermore, even though the cylinder shell 6 has a cylindrical shape according to the present embodiment and the cross-sectional shape of the outer circumferential surface is a circle, the present invention is not limited to such a structure of the cylinder shell. The cross-sectional shape of the outer circumferential surface of the cylinder shell 6 can be rectangular or polygonal.

[0056] Even if nothing is arranged on the back side of the lens 7a in the imaging unit 3 according to the present embodiment, it is still possible to use an imaging unit that is provided with a lens filter on the back side of the lens 7a. In the imaging unit 3, in which a transparent element such as a lens filter is arranged closest to an imaging plane (on the back side), and which captures the back side through the transparent element, the transparent element in the imaging unit 3 corresponds to the transparent element in the present invention. Reference symbol list 1 reverse imaging device 2 cases 2a Indentation 2b rear surface 2c outer circumferential surface 3 Imaging unit 6 cylinder jacket 6a rear end 7, 7a Lenses (transparent element) 11 Perimeter wall section 11a inner circumferential area 12 Floor 12a Floor area 13 through holes

Claims

[1] A backward imaging device (1) for attachment to a movable body, comprising: an imaging unit (3) which captures an image of the back side of the moving body; and a housing (2) that contains the imaging unit (3); wherein the imaging unit (3) comprises a cylindrical shell (6) which holds a transparent element (7, 7a); a recess (2a) is formed in a rear section of the housing (2); and the cylindrical shell (6) penetrates through a bottom (12) of the indentation (2a) and projects rearward from a bottom surface (12a) of the indentation (2a), characterized by , that a distance (L2) from an inner surface of the indentation (2a) to an edge of a rear end (6a) of the cylindrical shell (6) is equal to or greater than a projection length (L1) in the cylindrical shell (6). [2] A backward-facing imaging device (1) for attachment to a movable body, comprising: an imaging unit (3) which captures an image of the back side of the moving body; and a housing (2) that contains the imaging unit (3); wherein the imaging unit (3) comprises a cylindrical shell (6) which holds a transparent element (7, 7a); a recess (2a) is formed in a rear section of the housing (2); and the cylindrical shell (6) penetrates through a bottom (12) of the indentation (2a) and projects rearward from a bottom surface (12a) of the indentation (2a), characterized by , that the projection length (L1) in the cylindrical shell (6) is greater than a maximum width (L3) of an annular area between a rear edge of an outer circumferential surface (2c) of the housing (2) and an opening edge of the indentation (2a).

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