Camera unit

Abstract

Provided is a camera unit which suppresses an increase in polarizing filter size and product size caused by an increase in the angle of view. This camera unit comprises, for the purpose of minimizing an increase in product size caused by an increase in the angle of view, a lens, an image pickup element that receives light through the lens, and a lens filter disposed on the opposite side of the image pickup element relative to the lens and perpendicularly to the optical axis of the lens and is configured such that the lens filter is disposed so that the center of the lens filter is displaced from the center axis of the lens toward a direction of the increase in the angle of view.

Description

[Technical Field]

[0001] The present invention relates to an in-vehicle camera unit used in advanced driver assistance systems and the like. [Background technology]

[0002] Advanced driver assistance systems such as collision mitigation braking systems are effective means of preventing traffic accidents, and these systems use on-board cameras and millimeter-wave radar as external recognition sensors.

[0003] When an onboard camera is installed in a four-wheeled vehicle as an external environment recognition sensor, the housing of the onboard camera is generally attached to the upper part of the vehicle interior. In this case, the onboard camera in the vehicle interior captures images of the scenery and objects in front of the vehicle through the windshield. At this time, reflections from the windshield can cause the interior of the vehicle, such as the dashboard, to be reflected in the camera's imaging surface, which can degrade object recognition performance. Patent Documents 1 and 2 are known as prior art that address this issue.

[0004] For example, the abstract of Patent Document 1 states that the problem to be solved is to "prevent the reflection of the top of the instrument panel due to reflections on the inside of the windshield in an image recognition device using an in-vehicle stereo camera, thereby avoiding the impact on recognition performance." The solution is to "attach a polarizing filter 31 in front of the camera 2a (2b) so that its polarization axis is vertical. However, because the direction of the glass surface in front of the camera is not necessarily vertical due to the curvature of the windshield 10 in the left-right direction, the polarization axis of the camera's polarizing filter 31 is offset by an angle θ (where α is the vertical component of the angle between the camera's optical axis and the windshield on this optical axis, and β is the horizontal component, θ=tan -1 The document states that the vehicle-mounted camera is mounted so that it has a polarizing filter in front of the lens.

[0005] Furthermore, the abstract of Patent Document 2 states, "In a vehicle-mounted camera, ...the purpose is to prevent reflections of the dashboard or the like on the windshield." Paragraph 0015 of the specification states, "The camera 10 includes a camera body 20 and a case 22 that houses the camera body 20." Paragraph 0023 states, "The case 22 has an opening 22a on the side opposite the position of the harness coupler housing 42." Paragraph 0025 states, "The diameter of the opening 22a and the position of the lens unit 20c are appropriately determined according to the field of view (required angle of view) so as to prevent unwanted light from entering." Furthermore, Figures 3 and 4 of the same document show a case 22 that covers everything except the front of the lens unit 20c to prevent unwanted light from entering. Thus, the vehicle-mounted camera of Patent Document 2 prevents unwanted light from entering the lens unit by providing a case shaped to prevent reflections of the dashboard or the like on the windshield. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-94842 [Patent Document 2] Japanese Patent Application Publication No. 11-78737 Summary of the Invention [Problem to be solved by the invention]

[0007] In recent years, advanced driver assistance systems have been required to have further improved functionality, such as collision mitigation braking when turning right or left at intersections. Accordingly, in-vehicle cameras have been required to have a wider horizontal field of view. Furthermore, in-vehicle cameras for vehicles (such as large trucks and buses) that are mounted high and have a short distance from the camera mounting position to the front of the vehicle, a wider vertical field of view is also required so that the area below the camera can be monitored. Furthermore, as the number of in-vehicle cameras installed in compact vehicles such as minicars is increasing, in-vehicle cameras in recent years are being required to have not only a wider field of view but also a smaller size.

[0008] Generally, when the angle of view of an in-vehicle camera is widened, the amount of unwanted light reflected by the image sensor also increases. Even in the in-vehicle cameras described above, in which the imaging range of the camera is widened in a specific direction (up, down, left, or right) relative to the lens optical axis in consideration of collision damage mitigation braking when turning right or left at intersections and installation on large trucks and large buses, the reflection of unwanted light can be suppressed by using the polarizing filter described in Patent Document 1 or the case (lens hood) described in Patent Document 2. However, if the technical concepts described in both Patent Documents are applied as is, the polarizing filter and case (lens hood) will become larger in size to accommodate the wider angle of view, which will lead to an increase in the size of the camera as a whole. This could potentially reduce visibility from inside the vehicle or violate visibility regulations when installing an in-vehicle camera.

[0009] The present invention has been made in view of the above-mentioned problems, and has an object to provide a camera unit that suppresses the increase in polarizing filter and product size that accompanies a wider angle of view. [Means for solving the problem]

[0010] In order to solve the above problems, the present invention is characterized in that it comprises a lens, an image sensor that receives light through the lens, and a lens filter that is arranged on the opposite side of the lens from the image sensor and perpendicular to the optical axis of the lens, and the lens filter is arranged so that the center of the lens filter is shifted from the central axis of the lens in the direction of the wider angle of view. [Effects of the Invention]

[0011] The camera unit of the present invention can prevent the need for a lens hood and the product size from increasing due to the wider angle of view. Problems, configurations and effects other than those described above will become apparent from the following examples. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a top view of a vehicle equipped with a camera unit according to a first embodiment. [Figure 2] FIG. 1 is a perspective view showing a schematic configuration of a camera unit according to a first embodiment. [Figure 3] FIG. 3 is a cross-sectional view of the left camera and its surroundings of the camera unit in FIG. 2. [Figure 4] FIG. 10 is a perspective view showing a schematic configuration of a camera unit according to a second embodiment. [Figure 5] FIG. 5 is a cross-sectional view of the left camera and its surroundings of the camera unit in FIG. 4. [Figure 6] FIG. 11 is a cross-sectional view of the periphery of the left camera of the camera unit according to the third embodiment. [Figure 7A] FIG. 10 is a perspective view showing a schematic configuration of a camera unit according to a fourth embodiment. [Figure 7B] FIG. 10 is a perspective view showing a schematic configuration of a camera unit according to a fourth embodiment. [Figure 8A] FIG. 10 is a perspective view showing a schematic configuration of a camera unit according to a fifth embodiment. [Figure 8B] FIG. 10 is a perspective view showing a schematic configuration of a camera unit according to a fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an embodiment of the camera unit of the present invention will be described with reference to the drawings. [Example]

[0014] First, a camera unit 1 according to a first embodiment of the present invention will be described with reference to FIGS.

[0015] <Installation of camera unit 1 on vehicle V> 1 is a plan view from above of a vehicle V equipped with a camera unit 1 of this embodiment. This camera unit 1 is a stereo camera installed facing forward inside the cabin of the vehicle V, and as shown in the figure, the left camera's imaging area (solid line sector) is tilted to the right with respect to the lens optical axis direction (solid line arrow) and the right camera's imaging area (dashed line sector) is tilted to the left with respect to the lens optical axis direction (dashed line arrow), i.e., the imaging directions of both cameras are non-parallel.

[0016] Therefore, a stereo imaging area captured by the left and right cameras is formed in front of camera unit 1, an imaging area captured only by the left camera is formed to the right of the stereo imaging area, and an imaging area captured only by the right camera is formed to the left of the stereo imaging area. By designing the imaging areas of the left and right cameras in this way, the imaging range of camera unit 1 has a wide angle of view in the horizontal direction.

[0017] <Camera unit 1 configuration> 2 is a perspective view showing a schematic configuration of camera unit 1 of Example 1. As shown here, camera unit 1 has a housing 11, a pair of left and right lenses 12, a pair of left and right lens filters 13, and a pair of left and right lens hoods 14. In the following, up, down, front, back, left and right directions will be defined as shown in the figure.

[0018] The housing 11 is a metal housing that covers the image sensor 15, image processing circuitry, etc. (not shown) required to generate image data, and is manufactured, for example, from aluminum die-casting, which has high mechanical strength and excellent heat dissipation properties.

[0019] Lens 12 is an optical system for collecting light, located in front of image sensor 15, and is installed so as to protrude from the front surface of housing 11. Note that lens 12 does not need to be a single lens, and may be configured by combining multiple lenses so as to obtain desired optical characteristics.

[0020] Lens filter 13 is a light-transmitting member, such as a polarizing filter, arranged in front of lens 12. If only the function of protecting lens 12 is required, lens filter 13 may be made of a glass plate or plastic plate that does not have a polarizing function.

[0021] Lens hood 14 has a horizontally long opening on the front surface that is closed by lens filter 13, and is a light-shielding part that prevents unwanted light from outside the imaging areas of the left and right cameras (for example, from the dashboard direction) from entering lens 12 and degrading the quality of image data, and is formed to cover lens 12. In this embodiment, lens hood 14 also has the function of fixing and holding lens filter 13.

[0022] Figure 3 is a cross-sectional view of the area around the left camera of the camera unit 1 in Figure 2. Note that if Figure 2 is flipped horizontally, it becomes equivalent to a cross-sectional view of the area around the right camera, so detailed explanation of the right camera structure will be omitted hereafter.

[0023] As explained in FIG. 1, in the camera unit 1 of this embodiment, the imaging area of ​​the left camera is tilted to the right and the imaging area of ​​the right camera is tilted to the left, thereby achieving a wide horizontal angle of view for the entire camera unit 1.

[0024] 3, lens filter 13 must be extended to the right in front of lens 12 of the left camera so as to completely cover the wide rightward field of view, and lens hood 14 must be positioned farther away so as not to obstruct the wide rightward field of view. In contrast, lens filter 13 may be narrower in front of lens 12 of the left camera as long as it completely covers the narrow leftward field of view, and lens hood 14 can be positioned closer so as not to obstruct the narrow leftward field of view.

[0025] Therefore, in this embodiment, the horizontal center axes of lens filter 13 and lens hood 14 are arranged to the right (i.e., in the direction in which the imaging range is wider) by a predetermined offset amount δ from the horizontal center axis of lens 12. This makes it possible to reduce the size of the left side of lens filter 13 and lens hood 14 while maintaining the original functions of lens filter 13 and lens hood 14 compared to an arrangement in which the horizontal center axes are aligned, and therefore it is possible to reduce the size of camera unit 1 as a whole while widening the angle of view in the horizontal direction.

[0026] The magnitude of the offset amount δ for the left camera is roughly proportional to the width of the left camera's rightward field of view and inversely proportional to the width of the leftward field of view. Similarly, the magnitude of the offset amount δ for the right camera is roughly proportional to the width of the right camera's leftward field of view and inversely proportional to the width of the rightward field of view.

[0027] According to the camera unit of this embodiment described above, it is possible to suppress an increase in the size of the lens hood and the product that accompanies a wider angle of view. [Example]

[0028] Second Embodiment Next, a camera unit 1 according to a second embodiment of the present invention will be described with reference to Figures 4 and 5. Note that duplicated explanations of points common to the first embodiment will be omitted.

[0029] In Example 1, in order to provide camera unit 1 with a wider angle of view in the horizontal direction, the imaging ranges of the left and right cameras are made different on the left and right sides (horizontal direction) with respect to the lens optical axis. In this case, as illustrated in FIG. 3 , the size of lens filter 13 and the size of the opening of lens hood 14 are no longer optimized for the size of lens 12. This means that some of the light passing through lens filter 13 (e.g., light transmitted through the right side of lens filter 13 in FIG. 3 ) may be diffused by the front surface of housing 11, the side of lens 12, the rear surface of lens filter 13, the inner surface of lens hood 14, etc., and then enter the front of lens 12. In such a case, the diffused reflection within lens hood 14 degrades the quality of image data, so it is necessary to suppress the diffuse reflection within lens hood 14.

[0030] Therefore, in this embodiment, as shown in the perspective view of FIG. 4 and the cross-sectional view of FIG. 5, a light-blocking member 16 for reducing diffuse reflection of ambient light is provided inside the lens hood 14, thereby suppressing diffuse reflection within the lens hood 14.

[0031] In this embodiment, the light-blocking member 16 is made of an optically opaque black material that can block light in the visible range. The light-blocking member 16 is cut into a conical shape to fit the imaging range of the lens 12, and the cut surface is subjected to a surface treatment such as embossing to prevent light from being reflected on the cut surface. This makes it possible to suppress diffused reflection within the lens hood 14, even if the openings of the lens filter 13 and the lens hood 14 do not match the size of the lens 12 (see FIG. 5), and to prevent degradation of image data quality due to diffused reflection (such as the dashboard being reflected on the imaging element 15).

[0032] Here, the light blocking member 16 will be described in more detail using the cross-sectional view of Figure 5. As shown here, the light blocking member 16 also has the function of fixing the lens filter 13 by pressing the lens filter 13 against the lens hood 14 from the inside. This eliminates the need to provide a separate member (not shown in Figure 3) just for fixing the lens filter 13, and therefore reduces the number of parts that make up the camera unit 1.

[0033] 5, light-shielding member 16 is formed so as to surround the outer periphery of lens 12, and its front surface is formed at an angle to lens filter 13. That is, light-shielding member 16 is thin on the lens 12 side and thick on the opposite base side, ensuring the necessary mechanical strength while not blocking the imaging area of ​​the left camera.

[0034] In Figure 5, as a result of the lens filter 13 being shifted to the right, the left side of the light-shielding member 16 (first light-shielding area) is narrower and has a steeper front slope, while the right side of the light-shielding member 16 (second light-shielding area) is wider and has a gentler front slope. [Example]

[0035] Next, a camera unit 1 according to a third embodiment of the present invention will be described with reference to Fig. 6. Note that duplicated explanations of points common to the above-mentioned embodiments will be omitted.

[0036] In Example 2, diffused reflection inside the lens hood 14 was suppressed by disposing a light blocking member 16 inside the lens hood 14, but in this example, instead of the light blocking member 16 of Example 2, an optically opaque black light blocking body 17 is provided on the front surface of the housing 11 in a portion exposed inside the lens hood 14, as shown in the cross-sectional view of Fig. 6. Note that this light blocking body 17 may be painted, or may be a separate member attached.

[0037] Such black light blocking body 17 suppresses diffused reflection inside lens hood 14 even when housing 11 has a metallic luster, so that even when unwanted light enters the inside of lens hood 14, reflection on the front surface of housing 11 can be suppressed, and unwanted light can be prevented from being reflected onto imaging element 15. [Example]

[0038] Next, a camera unit 1 according to a fourth embodiment of the present invention will be described with reference to Figures 7A and 7B. Note that duplicated descriptions of points common to the above-mentioned embodiments will be omitted.

[0039] In Examples 1 to 3, a camera unit 1 with a wide horizontal field of view was exemplified to accommodate collision damage mitigation braking when turning right or left at an intersection. However, in the case of a camera unit 1 for vehicles in which the camera is mounted high and the distance from the camera mounting position to the front end of the vehicle is short, such as a camera unit for a large truck or large bus, a wide vertical field of view is required so that the area below the camera can also be monitored.

[0040] 7A, in camera unit 1 of this embodiment, lens filter 13 and lens hood 14 are made vertically long, and the vertical central axes of lens filter 13 and lens hood 14 are positioned downward (i.e., in the direction of the wider imaging range) from the vertical central axis of lens 12 by a predetermined offset amount δ. This makes it possible to monitor the area below camera unit 1 when mounted on a large truck or large bus, while also making camera unit 1 more compact.

[0041] Even when the configuration of this embodiment is adopted, in order to suppress diffuse reflection within the lens hood 14, a light-blocking member 16 may be placed inside the lens hood 14 (see FIG. 7B), or a light-blocking body 17 may be provided on the front surface of the housing 11. [Example]

[0042] Next, a camera unit 1 according to a fifth embodiment of the present invention will be described with reference to Figures 8A and 8B. Note that duplicated descriptions of points common to the above-mentioned embodiments will be omitted.

[0043] In Example 4, the field of view of the camera unit 1 is expanded downward assuming that the camera unit will be installed in a large truck or a large bus. In contrast, in the case of a camera unit to be installed in a low-profile vehicle or a cleaning robot, a wide angle of view is required, with the field of view expanded upward so that the area above the camera unit 1 can also be monitored.

[0044] 8A, in camera unit 1 of this embodiment, lens filter 13 and lens hood 14 are made vertically long, and the vertical central axes of lens filter 13 and lens hood 14 are positioned upward (i.e., in the direction of the wider imaging range) from the vertical central axis of lens 12 by a predetermined offset amount δ. This makes it possible to monitor the area above camera unit 1 when mounted on a low-profile vehicle or a cleaning robot, while also making camera unit 1 more compact.

[0045] Even when the configuration of this embodiment is adopted, in order to suppress diffuse reflection within the lens hood 14, a light-blocking member 16 may be placed inside the lens hood 14 (see FIG. 8B), or a light-blocking body 17 may be provided on the front surface of the housing 11. [Explanation of symbols]

[0046] REFERENCE SIGNS LIST 1... camera unit, 11... housing, 12... lens, 13... lens filter, 14... lens hood, 15... imaging element, 16... light-shielding member, 17... light-shielding body

Claims

1. Lenses and an image sensor that receives light through the lens; a lens filter disposed on the opposite side of the lens from the image sensor and perpendicular to the optical axis of the lens; a lens hood having an opening closed by the lens filter; a light blocking member that blocks light incident on the lens, the lens filter is disposed so that the center of the lens filter is shifted from the central axis of the lens; The lens hood is disposed so that the center of the lens hood is offset from the central axis of the lens, the light blocking member is formed so that a front surface thereof is disposed obliquely with respect to the lens filter, The camera unit is characterized in that the light blocking member is disposed inside the lens hood so as to surround the outer periphery of the lens.

2. 2. The camera unit according to claim 1, a light blocking member that blocks light incident on the lens, The camera unit is characterized in that the light-shielding member consists of a first light-shielding area and a second light-shielding area, the first light-shielding area and the second light-shielding area are located on either side of a non-light-shielding area that allows light to pass to the lens, and the first light-shielding area and the second light-shielding area have different inclinations of their front surfaces.

3. 2. The camera unit according to claim 1, a light blocking member that blocks light incident on the lens, A camera unit characterized in that the front surface of the light blocking member is arranged along the angle of view of the lens.

4. 2. The camera unit according to claim 1, a fixing member for fixing the lens filter; The camera unit is characterized in that the light blocking member also serves as the fixing member.

5. 2. The camera unit according to claim 1, the camera unit is a stereo camera having a plurality of the lenses and the imaging elements, A camera unit characterized in that the imaging directions of the plurality of lenses are non-parallel.

6. 2. The camera unit according to claim 1, A camera unit characterized in that the lens filter is long in the horizontal direction, and the horizontal center of the lens filter is offset in the horizontal direction from the horizontal center axis of the lens.

7. 2. The camera unit according to claim 1, A camera unit, characterized in that the lens filter is long in a vertical direction, and the vertical center of the lens filter is offset in the vertical direction from the vertical center axis of the lens.

Images