Optical system, image pickup apparatus, vehicle-mounted system, and mobile apparatus

Abstract

The invention relates to an optical system, an image pickup apparatus, a vehicle-mounted system, and a mobile apparatus. The optical system includes, in order from a magnification conjugate side to a reduction conjugate side, a front unit having a plurality of lenses, an aperture stop, and a rear unit having a plurality of lenses. A projection characteristic of the optical system, which represents a relationship between the half angle of view and the image height on the image plane, satisfies a predetermined condition.

Description

[0001] (This application is a divisional application of an application with a filing date of January 26, 2022, application number 202210093283.3, and invention name “Optical system, camera device, vehicle-mounted system, and mobile device”.) Technical Field

[0002] The present invention relates to an optical system suitable for an imaging device such as a vehicle-mounted camera. Background Art

[0003] An on-board camera is used to acquire image data around the vehicle and enable the user to visually identify other vehicles and obstacles. An optical system with a distortion correction projection characteristic close to y=f×tanθ is suitable for an on-board camera used to replace a rearview mirror, which is mainly used to enable the user to visually identify another vehicle in a far rear position. On the other hand, a fisheye lens of y=f×θ (equidistant projection), y=2f×sin(θ / 2) (stereographic projection) or y=f×sinθ (orthogonal projection) is suitable for an on-board camera mainly used to monitor a wide area near the vehicle. However, these fisheye lenses with projection characteristics have a low imaging magnification and are difficult to use as a substitute for a rearview mirror. Therefore, there is a need for an optical system with a wide viewing angle equal to that of a fisheye lens and a large imaging magnification of a central viewing angle area.

[0004] Japanese Patent Application ("JP") 2004-354572 discloses an optical system called a foveal lens having a projection characteristic in which the imaging magnification of the central viewing angle region is greater than the imaging magnification of the orthogonal projection method. JP 2007-155976 discloses an optical system as a foveal lens having a larger maximum viewing angle (half viewing angle 90°) than the optical system having an insufficient maximum viewing angle disclosed in JP 2004-354572.

[0005] As the optical system disclosed in JP 2007-155976 is required to have a wider angle of view, an image sensor for acquiring image data becomes larger and thus a camera becomes larger. Summary of the invention

[0006] The present invention provides an optical system and the like which have a sufficient angle of view and a sufficient imaging magnification in a central angle of view region and make an imaging apparatus small.

[0007] According to one aspect of the present invention, an optical system includes, in order from the magnification conjugate side to the reduction conjugate side, a front unit having a plurality of lenses, an aperture stop, and a rear unit having a plurality of lenses. A projection characteristic y(θ) of the optical system indicating a relationship between a half angle of view θ and an image height y on an image plane satisfies the following inequality:

[0008]

[0009] Wherein, θmax is the maximum half viewing angle of the optical system, and f is the focal length of the optical system. The differential value dy(θ) / dθ of the projection characteristic y(θ) at the half viewing angle θ has a local maximum.

[0010] According to another aspect of the present invention, a camera device includes: the above-mentioned optical system; and an image sensor configured to capture an object via the optical system. According to another aspect of the present invention, a vehicle-mounted system includes: the above-mentioned camera device; and a judger configured to judge the possibility of a collision between a vehicle and the object based on distance information of the object obtained from the camera device. According to another aspect of the present invention, a mobile device includes the above-mentioned camera device and is capable of moving while holding the camera device.

[0011] Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is a cross-sectional view of an optical system according to Example 1.

[0013] Figure 2A and 2B Projection characteristics of the optical system according to Example 1 are shown.

[0014] Figure 3 The curvature of the aspherical surface in the optical system according to Example 1 is shown.

[0015] Figure 4 Aberration diagrams of the optical system according to Example 1 are shown.

[0016] Figure 5 is a cross-sectional view of an optical system according to Example 2.

[0017] Fig. 6A and 6B The projection characteristics of the optical system according to Example 2 are shown.

[0018] Figure 7 The curvature of the aspherical surface in the optical system according to Example 2 is shown.

[0019] Figure 8Aberration diagrams of the optical system according to Example 2 are shown.

[0020] Fig. 9 is a cross-sectional view of an optical system according to Example 3.

[0021] Fig. 10A and 10B The projection characteristics of the optical system according to Example 3 are shown.

[0022] Fig.11 The curvature of the aspherical surface in the optical system according to Example 3 is shown.

[0023] Fig.12 Aberration diagrams of the optical system according to Example 3 are shown.

[0024] Fig.13 is a cross-sectional view of an optical system according to Example 4.

[0025] Fig.14A and 14B Projection characteristics of the optical system according to Example 4 are shown.

[0026] Fig.15 The curvature of the aspherical surface in the optical system according to Example 4 is shown.

[0027] Fig.16 Aberration diagrams of the optical system according to Example 4 are shown.

[0028] Fig.17 is a block diagram of a vehicle-mounted system using an optical system according to various examples.

[0029] Fig.18 is a schematic diagram of a main body portion of a vehicle including an onboard system.

[0030] Fig.19 is a flowchart showing an operation example of the in-vehicle system. DETAILED DESCRIPTION

[0031] Now, with reference to the accompanying drawings, a detailed description will be given of embodiments according to the present invention.

[0032] Figure 1 , 5, 9 and 13 respectively show optical systems 100 (100A, 100B, 100C and 100D) according to Examples 1, 2, 3 and 4. The optical system 100 according to each example is suitable for imaging devices such as digital still cameras, digital video cameras, car cameras, smart phone cameras, surveillance cameras, wearable cameras and medical cameras. In each figure, the left side is the magnification conjugate side (object side), and the right side is the reduction conjugate side (image side). The optical system 100 according to each example is an imaging optical system that collects a light beam from an unillustrated object located on the magnification conjugate side to form an object image on the image plane 300 on the reduction conjugate side. The imaging surface (light receiving surface) of an image sensor such as a CCD sensor and a CMOS sensor is arranged on the image plane. However, the optical system according to each example is a projection optical system that projects a light beam from a spatial light modulation element such as a liquid crystal panel arranged on the reduction conjugate side to a projector arranged on a projection surface such as a screen on the magnification conjugate side. In the following description, the optical system is used as an imaging optical system of a vehicle-mounted camera.

[0033] The optical system 100 according to each example includes a front unit 101 (101A to 101D) having a plurality of lenses, an aperture stop (iris) ST, and a rear unit 102 (102A to 102D) having a plurality of lenses in order from the magnification conjugate side to the reduction conjugate side. An IR cut filter 201 and a cover glass 202 are arranged between the optical system 100 and the image plane 300. As necessary, a low-pass filter or the like may be additionally arranged, or the IR cut filter 201 or the like may be omitted.

[0034] Aperture stops for limiting off-axis light beams may be arranged between the front unit 101 and the aperture stop ST and between the aperture stop ST and the rear unit 102 , respectively.

[0035] Example 1

[0036] In accordance with Figure 1 In the optical system 100A of Example 1 shown, the front unit 101A includes four lenses L1, L2, L3, and L4, and the rear unit 102A includes four lenses L5, L6, L7, and L8.

[0037] The lens L1 closest to the magnification conjugate position in the front unit 101A (optical system 100A) is an aspherical lens (first aspherical lens) having aspherical surfaces on both the magnification conjugate side and the reduction conjugate side. The paraxial refractive power (paraxial power) is negative.

[0038] The second lens L2 counted from the magnification conjugate side in the front unit 101A is an aspherical lens (second aspherical lens) having aspherical surfaces on both sides and having positive paraxial refractive power.

[0039] The third lens L3 and the fourth lens L4 counted from the magnification conjugate side in the front unit 101A are spherical lenses having negative and positive refractive powers, respectively.

[0040] Lens L5 as the lens closest to the magnification conjugate position and lens L6 and lens L7 as the second and third lenses counted from the magnification conjugate side in the rear unit 102A are spherical lenses having negative, positive and negative refractive powers, respectively.

[0041] The lens (final lens) L8 closest to the reduction conjugate position in the rear unit 102A (optical system 100A) is an aspherical lens (third aspherical lens) having aspherical surfaces on both sides and having positive paraxial refractive power.

[0042] The optical system 100A according to this example does not include a cemented lens and includes only a single lens. The vehicle-mounted camera may be placed in a high temperature environment (such as 70°C or higher) exposed to direct sunlight in summer, and may be placed in a low temperature environment below zero in winter. Therefore, the cemented lens may cause peeling due to the difference in linear expansion coefficient between cemented lens materials in the cemented lens, thereby using only a single lens.

[0043] Table 1 summarizes the numerical examples of the optical system 100A according to this example. (A) indicates the lens structure, f indicates the paraxial focal length (hereinafter also referred to as the focal length) (mm), and Fno indicates the F value. θmax indicates the maximum half angle of view (°). In order from the magnification conjugate side, the curvature radius r (mm) of the i-th surface, the distance d (mm) between the i-th surface and the (i+1)-th surface, the refractive index n of each optical element for the d-line, and the Abbe number ν based on the d-line of each optical element are indicated.

[0044] The Abbe number ν is expressed as follows:

[0045] ν=(Nd-1) / (NF-NC)

[0046] Here, Nd, NF and NC are refractive indices for d line (587.6 nm), F line (486.1 nm) and C line (656.3 nm) in the Fraunhofer line.

[0047] ST represents the position of the aperture stop. The surface with an asterisk * on the left has a spherical shape expressed by the following expression (1):

[0048]

[0049] Wherein, h is the coordinate in the radial direction from the optical axis, z is the coordinate in the optical axis direction (sag amount), r is the paraxial curvature radius, and k is the conic constant. The sign of z is positive in the direction from the magnification conjugate side to the reduction conjugate side.

[0050] (B) shows the cone constant k of each aspherical surface, and the aspherical coefficients B4, B6, B8, B10, B12, B14 and B16. “E±x” means “10 ±x ”. All aspherical coefficients not specifically described are 0. The description of this numerical example is the same as the other examples described below.

[0051] The optical system 100A according to this example is an optical system in which the angle formed by the optical axis and the most off-axis principal ray (i.e., the maximum half viewing angle θmax) is π / 2 (=90°), and has a maximum half viewing angle equal to that of a fisheye lens. The optical system 100A according to this example is an optical system in which the imaging magnification of the viewing angle region near the center (hereinafter referred to as the central viewing angle region) is larger than that of the fisheye lens.

[0052] Figure 2A and 2B The projection characteristics and resolution characteristics of the optical system 100A according to this example are shown respectively. Figure 2A and 2B , ° (degree) is used as the unit of viewing angle.

[0053] Figure 2A The projection characteristic y(θ) shown shows the relationship between the half viewing angle (angle formed by the optical axis and the incident light) θ and the image formation height (image height) y on the image plane 300 . Figure 2B The change in imaging height y for a small change in viewing angle at half viewing angle θ, that is, the differential value dy(θ) / dθ at half viewing angle θ of projection characteristic y(θ) is shown. The differential value dy(θ) / dθ corresponds to the local resolution at imaging height y, and the larger the value, the higher the local resolution. A high local resolution means a large local imaging magnification. The resolution in the following description means this local resolution.

[0054] The characteristic of the optical system 100A according to this example is that its projection characteristic y(θ) satisfies the following inequality (conditional expression) (2):

[0055]

[0056] Here, f represents the focal length of the optical system 100A, and θmax represents the maximum half viewing angle.

[0057] The optical system 100A according to this example has a resolution of the central viewing angle region (hereinafter referred to as the central resolution) higher than the resolution of the orthogonal projection method (y(θ)=f×sinθ), wherein the central resolution of the orthogonal projection method is high among the projection methods used for general fisheye lenses. In the case where the value is lower than the lower limit in the inequality (2), the central resolution may become lower than the central resolution of the fisheye lens of the orthogonal projection method having the same maximum imaging height, or the maximum imaging height may become larger and the optical system may become larger.

[0058] In the case where the value is higher than the upper limit in expression (2), the resolution near the center becomes too high, and it becomes difficult to obtain a viewing angle equal to that of a fisheye lens. Alternatively, even if a viewing angle equal to that of a fisheye lens can be obtained, good optical performance may not be guaranteed in a high viewing angle region.

[0059] The numerical range of inequality (2) can be set as follows:

[0060]

[0061] The numerical range of inequality (2) can be set as follows

[0062]

[0063] In order to obtain a wide viewing angle equal to that of a fisheye lens, the maximum half viewing angle θmax may satisfy the following inequality (3). In inequality (3), radians are used as the unit of the viewing angle.

[0064]

[0065] When the following inequalities (3)′ and (3)″ are satisfied, a wide viewing angle closer to that of a fisheye lens can be obtained.

[0066]

[0067]

[0068] The optical system 100A according to this example has a characteristic close to the projection characteristic (y=f×tanθ) of a general imaging optical system to suppress optical distortion in a low viewing angle region and prevent a decrease in center resolution. Figure 2B As will be appreciated, a higher resolution than the on-axis resolution (at viewing angle 0) can be obtained in the low viewing angle region.

[0069] Since optical distortion is suppressed in the low-angle area, distortion near the center of the captured image can be reduced, so that the detection accuracy of other vehicles such as the preceding vehicle and the following vehicle can be improved. When the captured image in the low-angle area is displayed on a monitor instead of a rearview mirror, a natural sense of perspective can be visually obtained, and electronic distortion correction becomes unnecessary or the correction amount can be reduced. Therefore, good visibility can be obtained while suppressing image degradation.

[0070] In the optical system 100A according to this example, as the viewing angle increases from the optical axis, the resolution in the low viewing angle region increases, and as the viewing angle decreases, the resolution in the high viewing angle region decreases. Figure 2B As shown, the resolution has a local maximum at a half viewing angle θa, which is a boundary between a low viewing angle region and a high viewing angle region.

[0071] On the contrary, when the optical system 100A is configured so that the resolution has a local maximum at the half viewing angle θa, the following projection characteristics can be achieved: as the viewing angle increases, the resolution increases in the low viewing angle area, and the resolution decreases in the high viewing angle area. The half viewing angle θa at which the resolution (differential value dy(θ) / dθ) has a local maximum can satisfy the following inequality (4).

[0072]

[0073] When the value is lower than the lower limit in inequality (4), the low viewing angle region with high resolution becomes too narrow. When the value is higher than the upper limit in inequality (4), the low viewing angle region with high resolution becomes too wide, and it becomes difficult to obtain a viewing angle equal to that of a fisheye lens, or it becomes difficult to ensure good optical performance in a high viewing angle region even when a viewing angle equal to that of a fisheye lens is obtained.

[0074] The numerical range of inequality (4) can be set as follows.

[0075]

[0076] The numerical range of inequality (4) can be set as follows.

[0077]

[0078] Except for the on-axis position (at viewing angle 0), at a half viewing angle θ smaller than the half viewing angle θa at which the resolution has a local maximum, the projection characteristic y(θ) of the optical system 100A may satisfy the following inequality (5):

[0079]

[0080] In the case where inequality (5) is not satisfied, the resolution in the low viewing angle area is reduced. Since y(θ) / θ is equal to f on the optical axis in principle regardless of the projection characteristics, the on-axis position is excluded. In this example, y(θ)≈f×tanθ is satisfied in the viewing angle area where the half viewing angle is less than θa, so that inequality (5) is satisfied.

[0081] In order to obtain high resolution in a low viewing angle region and a wide viewing angle equivalent to that of a fisheye lens, a half viewing angle θb satisfying the following equation (6) may satisfy the following inequality (7).

[0082]

[0083]

[0084] The right side of equation (6) is a value obtained by dividing the maximum imaging height y(θmax) by the maximum half viewing angle θmax, and represents the average resolution. Therefore, the half viewing angle θb is a half viewing angle at which the actual resolution is equal to the average resolution. By setting the half viewing angle θb that provides the average resolution to a value close to 1 / 2 of the maximum half viewing angle, the balance between the resolution in the low viewing angle area and the resolution in the high viewing angle area can be improved, high resolution in the low viewing angle area and good optical performance can be obtained, and a wide viewing angle equal to that of a fisheye lens can be ensured.

[0085] When the value is lower than the lower limit in inequality (7), the low viewing angle region with high resolution becomes too narrow. When the value is higher than the upper limit in inequality (7), it becomes difficult to obtain a wide viewing angle equivalent to that of a fisheye lens, or it becomes difficult to ensure good optical performance in a high viewing angle region even when a wide viewing angle equivalent to that of a fisheye lens can be obtained.

[0086] The numerical range of inequality (7) can be set as follows.

[0087]

[0088] In the orthogonal projection method having high center resolution among the projection methods of the general fisheye lens, in the case where the maximum half viewing angle θmax is π / 2 as in this example, the resolution is 0 at the outermost peripheral viewing angle (at the maximum half viewing angle θmax). The resolution of 0 at the outermost peripheral viewing angle is not suitable for a vehicle-mounted camera for monitoring the surroundings of a vehicle. The optical system 100A according to this example is configured so that the resolution is guaranteed to be higher than a specific value rather than 0 even at the outermost peripheral viewing angle when the maximum half viewing angle θmax is π / 2. More specifically, the resolution (differential value dy(θ) / dθ) at the viewing angle (outermost peripheral viewing angle) θ corresponding to the maximum half viewing angle θmax can satisfy the following inequality (8):

[0089]

[0090] When the value is lower than the lower limit of inequality (8), the resolution at the outermost peripheral viewing angle becomes too narrow. When the value is higher than the upper limit in inequality (8), the resolution at the outermost peripheral viewing angle becomes high, and the viewing angle area with high resolution becomes too narrow.

[0091] The numerical range of inequality (8) can be set as follows.

[0092]

[0093] The numerical range of inequality (8) can be set as follows.

[0094]

[0095] In the optical system 100A according to this example, in order to realize the projection characteristics as described above, the front unit 101A arranged on the magnification conjugate side of the aperture stop ST includes the first aspherical lens L1. The first aspherical lens L1 can satisfactorily correct off-axis aberrations such as field curvature. The first aspherical lens L1 may have a negative paraxial refractive power. This structure can easily correct off-axis aberrations in the case of a wide viewing angle equal to that of a fisheye lens.

[0096] The optical system 100A according to this example may include a second aspherical lens L2 on the reduction conjugate side of the first aspherical lens L1 to more effectively correct off-axis aberrations. The second aspherical lens L2 may have a positive paraxial refractive power. This structure can easily correct off-axis aberrations while improving the central resolution.

[0097] The first aspherical lens L1 and the second aspherical lens L2 may each be a meniscus-shaped lens having a convex surface facing the object side. This is advantageous when correcting curvature of field.

[0098] Figure 3 The curvatures of the aspherical surfaces (first surface, second surface) of lens L1 and the curvatures of the aspherical surfaces (third surface, fourth surface) of lens L2 are shown for each radial position. In each figure, the portion surrounded by a dotted circle indicates an inflection point where the sign of the curvature is reversed (since it is a radial position, it is a circle centered on the optical axis).

[0099] As described above, the optical system 100A according to this example suppresses optical distortion in the low viewing angle region and has a projection characteristic close to the projection characteristic (y=f×tanθ) of a general imaging optical system. In the case where at least one of the aspherical surfaces of the lenses L1 and L2 has an inflection point, the projection characteristic in the low viewing angle region is made closer to f×tanθ, and optical distortion becomes easy to suppress.

[0100] In the case where at least one aspherical surface (such as the first surface and the second surface) can have a plurality of inflection points, the resolution at the maximum half viewing angle θmax can be easily made high.

[0101] The refractive index n1 of lens L1 for the d-line may satisfy the following inequality (9).

[0102]

[0103] Since lens L1 has a meniscus shape whose surface on the magnification conjugate side is convex, when the refractive index of lens L1 is low so as not to satisfy inequality (9), the processing difficulty becomes higher due to the increase in the amount of droop and the amount of aspherical surface of the meniscus shape. This is not preferable in terms of miniaturization such as shortening the optical path length and reducing the diameter of the optical system.

[0104] The refractive index n2 of lens L2 for the d-line may satisfy the following inequality (10).

[0105]

[0106] As described above, lens L1 has negative paraxial refractive power, and lens L2 has positive paraxial refractive power. In order to reduce the Petzval sum, the refractive index n2 of lens L2 may be greater than the refractive index n1 of lens L1.

[0107] In order to obtain a viewing angle equal to that of a fisheye lens while improving the central resolution, the (paraxial) focal length fa of the front unit 101A may satisfy the following inequality (11).

[0108]

[0109] When the value is higher than the upper limit in inequality (11), the center resolution becomes lower than the center resolution of the fisheye lens of the orthogonal projection method, and it becomes difficult to obtain a wide viewing angle equal to that of the fisheye lens, or it becomes difficult to ensure good optical performance in the high viewing angle area even when a wide viewing angle equal to that of the fisheye lens can be obtained.

[0110] The lens L4 closest to the reduction conjugate position in the front unit 101A may be a lens whose convex surface faces the reduction conjugate side. In an off-axis light beam at a high viewing angle, coma aberration occurs when the light beam is significantly bent by the lens L1, but the lens L4 may be the above-mentioned lens for better correction of coma aberration.

[0111] The lens L8 closest to the reduction conjugate position in the rear unit 102A may have positive refractive power. Since the lens L8 is the lens closest to the reduction conjugate side having a large off-axis beam height, when the lens L8 has positive refractive power, the incident angle of light on the image plane 300 in the high viewing angle region may be reduced. Therefore, a wide viewing angle equivalent to that of a fisheye lens may be easily obtained while ensuring good optical performance and high center resolution.

[0112] Since an aspherical lens is effective for better correction of off-axis aberrations such as field curvature, the lens L8 may be an aspherical lens. However, in the case where the lens L8 is an aspherical lens, in order to maintain the effect of reducing the incident angle of light on the image plane 300 in the high viewing angle area, the aspherical lens needs positive refractive power at the periphery.

[0113] In the rear unit 102A, the lens L6 and the lens L7 arranged on the magnification conjugate side of the lens L8 may have positive and negative refractive powers, respectively. In order to shorten the total length of the optical system 100A that forms an image of an object on the image plane 300 and reduce the size of the optical system 100A, the focal length of the rear unit 102A as a whole needs to be positive. Therefore, the rear unit 102A needs to have a lens with positive refractive power, but in the case where the refractive power of all the lenses constituting the rear unit 102A is positive, for example, spherical aberrations occurring in all the lenses constituting the rear unit 102A are all added. With regard to off-axis aberrations such as coma, in the case where the lens L8 has positive refractive power, in order to correct the off-axis aberration, it is more effective to arrange a lens with negative refractive power at a position where the height of the off-axis light is large. Therefore, the refractive power of the lens L6 on the magnification conjugate side may be positive, and the refractive power of the lens L7 on the reduction conjugate side may be negative.

[0114] The refractive power of lens L5 can be determined according to the sign of the focal length fa of front unit 102A. In this example, because the focal length fa of front unit 102A is positive, the refractive power of lens L5 is set to negative. Thus, the residual spherical aberration of front unit 102A can be corrected by lens L5, and it becomes easier to obtain better optical performance.

[0115] As described above, the lens L8 has the effect of reducing the incident angle of light on the image plane 300 in the high viewing angle region. Therefore, the following inequality (12) can be satisfied:

[0116]

[0117] Wherein, D is the distance on the optical axis from the aperture stop ST to the surface on the reduction conjugate side of the lens L8, and L is the total length of the optical system 100A (the distance from the surface on the magnification conjugate side of the lens L1 to the surface on the reduction conjugate side of the lens L8).

[0118] This inequality (12) can increase the height of the off-axis light in lens L8 while reducing the size of the optical system 100A in the radial direction. In the case of a value higher than the upper limit in inequality (12), since the aperture stop ST is located on the magnification conjugate side, the height of the off-axis light in lens L8 can be easily increased, but the diameter of lens L8 becomes larger. In the case of a value lower than the lower limit in inequality (12), since the aperture stop ST is located on the reduction conjugate side, it is difficult to increase the height of the off-axis light in lens L8, and further, the diameter of lens L1 becomes larger.

[0119] The numerical range of inequality (12) can be set as follows.

[0120]

[0121] Figure 4 Longitudinal aberrations (spherical aberration, astigmatism, distortion, and lateral chromatic aberration) of the optical system 100A according to this example are shown. In the spherical aberration diagram, Fno represents the F value, the solid line represents the spherical aberration for the d-line (wavelength 587.6nm), the double-dashed line represents the spherical aberration for the C-line (wavelength 656.3nm), and the single-dashed line represents the spherical aberration for the F-line (wavelength 486.1nm), respectively. In the astigmatism diagram, the solid line S represents the sagittal image plane, and the dotted line M represents the meridional image plane. In the astigmatism diagram, the difference between the sagittal image plane and the meridional image plane is astigmatism, and each fluctuation represents the field curvature. Distortion is shown for the d-line. The chromatic aberration diagram represents the lateral chromatic aberration for the C-line and the F-line. ω is the half viewing angle (°). The horizontal axes of the spherical aberration diagram and the astigmatism diagram are set to ±0.2 mm, the horizontal axis of the distortion diagram is set to ±100%, and the horizontal axis of the chromatic aberration diagram is set to ±0.01 mm. The description of these aberration diagrams is the same as another example described below.

[0122] As per Figure 4 As understood, in the optical system 100A according to this example, spherical aberration, field curvature, astigmatism and lateral chromatic aberration are satisfactorily corrected. Distortion is small in the low viewing angle region, and distortion increases as imaging height increases in the high viewing angle region. In order to ensure high resolution, the projection characteristic in the low viewing angle region is close to y=f×tanθ.

[0123] Table 2 summarizes the parameter values ​​in this example (numerical example) and the values ​​of each inequality in the above inequality (except inequality (5)). As understood from Table 2, the optical system 100A according to this example satisfies all inequalities. Therefore, the optical system 100A according to this example has high center resolution, a wide viewing angle equal to that of a fisheye lens, and good optical performance.

[0124] Example 2

[0125] according to Figure 5 The basic structure of the optical system 100B of Example 2 shown is the same as that of the optical system 100A according to Example 1, and components corresponding to those of the optical system 100A according to Example 1 will be designated by the same reference numerals.

[0126] The front unit 101B includes four lenses L1 to L4. Lens L1 is an aspheric lens (first aspheric lens) having aspheric surfaces on both sides, and has negative paraxial refractive power. Lens L2 is an aspheric lens (second aspheric lens) having aspheric surfaces on both sides, and has positive paraxial refractive power. Lenses L3 and L4 are spherical lenses, and have negative and positive refractive powers, respectively.

[0127] The rear unit 102B includes four lenses L5 to L8. Lenses L5, L6, and L7 are spherical lenses and have negative, positive, and negative refractive powers, respectively. Since the sign of the focal length fa of the front unit 101A in this example is opposite to that of Example 1, the sign of the refractive power of lens L5 is different from that according to Example 1.

[0128] The lens L8 is an aspherical lens (third aspherical lens) including aspherical surfaces on both sides, and has positive paraxial refractive power. As in Example 1, the lens L8 also has positive refractive power in the periphery.

[0129] Numerical examples of the optical system 100B according to this example are summarized in Table 3. The optical system 100B according to this example is an optical system having a maximum half viewing angle θmax of π / 2, which is equal to that of a fisheye lens.

[0130] Fig. 6A and 6B The projection characteristics and resolution characteristics of the optical system 100B according to this example are shown respectively. As understood from these figures, the optical system 100B according to this example has a wide viewing angle equal to that of a fisheye lens and a higher central resolution than that of a fisheye lens.

[0131] Figure 7The curvature of the aspherical surface (first surface, second surface) of lens L1 and the curvature of the aspherical surface (third surface, fourth surface) of lens L2 for each radial position are shown. In this example, the first, second and third surfaces have an inflection point, and the second and third surfaces have two inflection points. Although the surface having two inflection points is different from the surface of Example 1, the effect obtained is the same.

[0132] Figure 8 The longitudinal aberration of the optical system 100B according to this example is shown. As can be understood from the figure, in the optical system 100B according to this example, spherical aberration, field curvature, astigmatism and lateral chromatic aberration are satisfactorily corrected. The distortion is small in the low viewing angle area, and the distortion increases as the imaging height increases in the high viewing angle area. In order to ensure high resolution, the projection characteristics in the low viewing angle area are close to y=f×tanθ.

[0133] Table 4 summarizes the parameter values ​​in this example (numerical example) and the values ​​of each inequality in the above inequality (except inequality (5)). As understood from Table 4, the optical system 100B according to this example satisfies all inequalities. Therefore, the optical system 100B according to this example has high center resolution, a wide viewing angle equal to that of a fisheye lens, and good optical performance.

[0134] Example 3

[0135] according to Fig. 9 The optical system 100C of the illustrated example 3 is different from the respective optical systems of examples 1 and 2 in that the front unit 100C includes a cover glass lens GL closest to the magnification conjugate position and three lenses L1 to L3. The cover glass lens GL serves as a cover glass for protecting the lens L1 and a lens having a refractive power. Therefore, without the cover glass lens GL, the optical performance of the optical system 100C cannot be guaranteed. The cover glass lens GL is designed to be insensitive to arrangement errors so that it can be easily replaced in the event that the cover glass lens GL is damaged or scratched.

[0136] Lens L1 is an aspheric lens (first aspheric lens) including aspheric surfaces on both sides, and has negative paraxial refractive power. Lens L2 is an aspheric lens (second aspheric lens) including aspheric surfaces on both sides, and has positive paraxial refractive power. Lens L3 is a spherical lens and has negative refractive power.

[0137] The rear unit 102C includes four lenses L4 to L7. Lenses L4, L5, and L6 are spherical lenses, and have positive, positive, and negative refractive powers, respectively. Lens L7, which is the final lens, is an aspherical lens (third aspherical lens) having aspherical surfaces on both sides, and has positive paraxial refractive power. Similar to lens L8 in Examples 1 and 2, lens L7 has positive refractive power at the periphery.

[0138] In this example, the front unit 101C includes four lenses including a cover glass lens GL to suppress an increase in the total length of the optical system 100C due to the provision of the cover glass lens GL. Unlike Examples 1 and 2, the lens L3 closest to the reduction conjugate position in the front unit 101C has a negative refractive power, and similar to Examples 1 and 2, the convex surface facing the reduction conjugate side satisfactorily corrects coma aberration.

[0139] Numerical examples of the optical system 100C according to this example are summarized in Table 5. The optical system 100C according to this example is an optical system having a maximum half viewing angle θmax of π / 2, which has a maximum half viewing angle equal to that of a fisheye lens.

[0140] Fig. 10A and Fig. 10B The projection characteristics and resolution characteristics of the optical system 100C according to this example are shown respectively. As understood from these figures, the optical system 100C according to this example has a wide viewing angle equal to that of a fisheye lens and a higher central resolution than that of a fisheye lens.

[0141] Fig.11 The curvature of the aspherical surface (third surface, fourth surface) of lens L1 and the curvature of the aspherical surface (fifth surface, sixth surface) of lens L2 for each radial position are shown. In this example, the third, fourth and fifth surfaces have an inflection point, and the fourth and fifth surfaces have two inflection points. Although the surface having two inflection points is different from the surface of Example 1, the effect obtained is the same.

[0142] Fig.12 The longitudinal aberration of the optical system 100C according to this example is shown. As understood from this figure, in the optical system 100C according to this example, spherical aberration, field curvature, astigmatism, and lateral chromatic aberration are satisfactorily corrected. The distortion is small in the low viewing angle region, and the distortion increases as the imaging height increases in the high viewing angle region. In order to ensure high resolution, the projection characteristic in the low viewing angle region is close to y=f×tanθ.

[0143] Table 6 summarizes the parameter values ​​in this example (numerical example) and the values ​​of each inequality in the above inequality (except inequality (5)). As understood from Table 6, the optical system 100C according to this example satisfies all inequalities. Therefore, the optical system 100C according to this example has high center resolution, a wide viewing angle equal to that of a fisheye lens, and good optical performance.

[0144] Example 4

[0145] according to Fig.13 The optical system 100D of Example 4 shown is different from the other examples in that there is no third aspherical lens and the spherical lens L7 is arranged closest to the reduction conjugate position in the rear unit 102D.

[0146] The front unit 101D includes three lenses L1 to L3. Lens L1 is an aspheric lens (first aspheric lens) having aspheric surfaces on both sides, and has negative paraxial refractive power. Lens L2 is an aspheric lens (second aspheric lens) having aspheric surfaces on both sides, and has positive paraxial refractive power. Lens L3 is a spherical lens and has positive refractive power.

[0147] The rear unit 102D includes four lenses L4 to L7. Lenses L4 to L7 are spherical lenses and have positive, positive, negative and positive refractive powers, respectively. In this example, the front unit 101D includes three lenses, and a spherical lens (final lens) L7 with positive refractive power is arranged in the rear unit 102D instead of the third aspherical lens.

[0148] The lens L7, which is a spherical lens, has positive refractive power even at the periphery. This lens L7 can be provided to reduce the incident angle of light on the image plane 300 in the high viewing angle region and obtain high center resolution and a wide viewing angle equivalent to that of a fisheye lens.

[0149] The lens L3 closest to the reduction conjugate position in the front unit 101D has a convex surface facing the reduction conjugate side and has never satisfactorily corrected coma aberration similar to other examples.

[0150] Numerical examples of the optical system 100D according to this example are summarized in Table 7. The optical system 100D according to this example is an optical system having a maximum half viewing angle θmax of π / 2, which has a maximum half viewing angle equal to that of a fisheye lens.

[0151] Fig.14A and 14B The projection characteristics and resolution characteristics of the optical system 100D according to this example are shown respectively. As understood from these figures, the optical system 100D according to this example has a wide viewing angle equal to that of a fisheye lens and a higher central resolution than that of a fisheye lens.

[0152] Fig.15 The curvature of the aspherical surface (first surface, second surface) of lens L1 and the curvature of the aspherical surface (third surface, fourth surface) of lens L2 for each radial position are shown. In this example, the first, second and third surfaces have an inflection point, and the second and third surfaces have two inflection points. Although the surface having two inflection points is different from the surface of Example 1, the effect obtained is the same.

[0153] Fig.16 The longitudinal aberration of the optical system 100D according to this example is shown. As understood from this figure, in the optical system 100D according to this example, spherical aberration, field curvature, astigmatism, and lateral chromatic aberration are satisfactorily corrected. Distortion is also small in the low viewing angle region, and distortion also increases as the imaging height increases in the high viewing angle region. In order to ensure high resolution, the projection characteristics in the low viewing angle region are close to y=f×tanθ.

[0154] Table 8 summarizes the parameter values ​​in this example (numerical example) and the values ​​of each inequality in the above inequality (except inequality (5)). As understood from Table 8, the optical system 100D according to this example satisfies all inequalities. Therefore, the optical system 100D according to this example has high center resolution, a wide viewing angle equal to that of a fisheye lens, and good optical performance.

[0155] Table 1

[0156]

[0157] Table 2

[0158] parameter value f 4.500 θmax 1.571 θa 0.262 θb 0.664 y(θmax) 3.650 <![CDATA[dy(θ) / dθ| θ＝θmax ]]> 0.433 <![CDATA[n1]]> 1.639 <![CDATA[n2]]> 1.851 fa 14.431 D 9.580 L 21.160 f×sinθmax / y(θmax) 1.233 θmax / π 0.500 θa / θmax 0.167 θb / θmax 0.422 <![CDATA[(dy(θ) / dθ| θ＝θmax ) / f]]> 0.096 <![CDATA[n1 / 1.6]]> 1.024 <![CDATA[n2 / n1]]> 1.130 |f / fa| 0.312 D / L 0.453

[0159] Table 3

[0160]

[0161] Table 4

[0162] parameter value f 4.867 θmax 1.571 θa 0.305 θb 0.722 y(θmax) 4.365 <![CDATA[dy(θ) / dθ| θ＝θmax ]]> 0.172 <![CDATA[n1]]> 1.639 <![CDATA[n2]]> 1.851 fa -10.398 D 9.833 L 20.915 f×sinθmax / y(θmax) 1.115 θmax / π 0.500 θa / θmax 0.194 θb / θmax 0.460 <![CDATA[(dy(θ) / dθ| θ＝θmax ) / f]]> 0.035 <![CDATA[n1 / 1.6]]> 1.024 <![CDATA[n2 / n1]]> 1.130 |f / fa| 0.468 D / L 0.470

[0163] Table 5

[0164]

[0165] Table 6

[0166] parameter value f 4.853 θmax 1.57 θa 0.253 θb 0.732 y(θmax) 4.345 <![CDATA[dy(θ) / dθ| θ＝θmax ]]> 0.361 <![CDATA[n1]]> 1.703 <![CDATA[n2]]> 1.808 fa -5.880 D 9.328 L 21.500 f×sinθmax / y(θmax) 1.117 θmax / π 0.500 θa / θmax 0.161 θb / θmax 0.466 <![CDATA[(dy(θ) / dθ| θ＝θmax ) / f]]> 0.074 <![CDATA[n1 / 1.6]]> 1.064 <![CDATA[n2 / n1]]> 1.062 |f / fa| 0.825 D / L 0.434

[0167] Table 7

[0168]

[0169] Table 8

[0170] parameter value f 4.780 θmax 1.57 θa 0.375 θb 0.759 y(θmax) 4.361 <![CDATA[dy(θ) / dθ| θ＝θmax ]]> 0.189 <![CDATA[n1]]> 1.808 <![CDATA[n2]]> 1.832 fa -22.751 D 10.468 L 21.081 f×sinθmax / y(θmax) 1.096 θmax / π 0.500 θa / θmax 0.239 θb / θmax 0.483 <![CDATA[(dy(θ) / dθ| θ＝θmax ) / f]]> 0.040 <![CDATA[n1 / 1.6]]> 1.130 <![CDATA[n2 / n1]]> 1.013 |f / fa| 0.210 D / L 0.497

[0171] Fig.17 The structure of an on-vehicle camera 10 using an optical system according to any one of the above-described examples as an imaging optical system, and an on-vehicle system (driving support device) 600 having the on-vehicle camera 10 is shown. The on-vehicle system 600 is a system held by a movable moving body (mobile device) such as an automobile (vehicle), and is configured to support driving (steering) of the vehicle based on image information of the vehicle's surroundings acquired by the on-vehicle camera 10.

[0172] Fig.18 A vehicle 700 is shown as a mobile device including the in-vehicle system 600. Fig.18 The imaging range 50 of the vehicle-mounted camera 10 is shown to be set to the front of the vehicle 700 , but the imaging range 50 may be set to the rear or side of the vehicle 700 .

[0173] like Fig.18 As shown, the vehicle-mounted system 600 includes a vehicle-mounted camera 10, a vehicle information acquisition device 20, a control device (controller, ECU: electronic control unit) 30 and a warning device (warning unit) 40. The vehicle-mounted camera 10 includes a camera unit 1, an image processor 2, a parallax calculator 3, a distance acquirer 4 and a collision judge 5. The image processor 2, the parallax calculator 3, the distance acquirer 4 and the collision judge 5 constitute a processing unit. The camera unit 1 includes an optical system and an image sensor according to any one of the above examples.

[0174] Fig.19 The flowchart of FIG. 6 shows an operation example of the in-vehicle system 600. In step S1, the in-vehicle system 600 uses the imaging unit 1 to image an object such as an obstacle or a pedestrian around the vehicle, and acquires a plurality of image data (parallax image data).

[0175] In step S2, vehicle information is acquired by the vehicle information acquisition device 20. The vehicle information is information including the vehicle speed, yaw rate, steering angle, etc. of the vehicle.

[0176] In step S3, the image processor 2 performs image processing on the multiple image data acquired by the camera unit 1. More specifically, image feature analysis is performed to analyze feature quantities such as edge quantity, edge direction, and density value in the image data. The image feature analysis may be performed on each of the multiple image data, or may be performed on only part of the multiple image data.

[0177] In step S4, the parallax calculator 3 calculates the parallax (image offset) information between the plurality of image data acquired by the imaging unit 1. The method for calculating the parallax information can use a known method such as the SSDA method or the area correlation method, and the description thereof will be omitted. Steps S2, S3, and S4 may be performed in this order, or may be processed in parallel.

[0178] In step S5, the distance acquirer 4 acquires (calculates) distance information from the object imaged by the imaging unit 1. The distance information may be calculated based on the parallax data calculated by the parallax calculator 3, and internal and external parameters of the imaging unit 1. The distance information is information about a relative position to an object (such as a distance to the object, a defocus amount, an image shift amount, etc.), and may directly represent a distance value of an object in an image, or indirectly represent information corresponding to the distance value.

[0179] Then, in step S6, the collision determiner 5 determines whether the distance to the object is included in the preset distance range using the vehicle information acquired by the vehicle information acquisition device 20 or the distance information calculated by the distance acquirer 4. This structure can determine whether the object exists within the set distance around the vehicle, and determine the possibility of collision between the vehicle and the object. The collision determiner 5 determines that "there is a possibility of collision" (step S7) when the object exists within the set distance, and determines that there is no possibility of collision when the object does not exist within the set distance (step S8).

[0180] Next, when the collision determiner 5 determines that "there is a possibility of collision", the collision determiner 5 notifies (transmits) the judgment result to the control device 30 and the warning device 40. At this time, the control device 30 controls the vehicle based on the judgment result of the collision determiner 5 (step S6), and the warning device 40 provides a warning to the vehicle user (driver, passenger) based on the judgment result of the collision determiner 5 (step S7). The judgment result can be notified to at least one of the control device 30 and the warning device 40.

[0181] The control device 30 can control the movement of the vehicle by outputting a control signal to a drive unit (engine, motor, etc.) in the vehicle. For example, the control device 30 generates a control signal for applying the brakes, resuming the accelerator, turning the steering wheel, and applying a braking force to each wheel in the vehicle, and controls the vehicle to suppress the output of the engine or motor. The warning device 40 gives a warning to the user, for example, by emitting a warning sound (alarm), displaying a warning message on the screen of the car navigation system, or giving vibration to the seat belt or the steering wheel.

[0182] According to the vehicle-mounted system 600 as described above, the above processing can effectively detect an object and avoid a collision between the vehicle and the object. In particular, by applying an optical system according to any one of the above examples to the vehicle-mounted system 600, the vehicle-mounted camera 10 as a whole can be made smaller while increasing the degree of freedom of arrangement, and can detect an object at a wide viewing angle and determine the possibility of collision.

[0183] Various methods can be used to calculate the distance information. For example, a pupil division type image sensor including a plurality of pixel units regularly arranged in a two-dimensional array is used for the image sensor of the imaging unit 1. In the pupil division type image sensor, one pixel unit includes a micro lens and a plurality of photoelectric conversion units, receives a pair of light beams that have passed through different areas in the pupil of the optical system, and outputs a pair of image data from each photoelectric conversion unit.

[0184] The image shift amount of each area is calculated by correlation calculation between the image data pairs, and image shift map data representing the distribution of the image shift amount is calculated by the distance acquirer (distance calculator) 4. Alternatively, the distance acquirer 4 may also convert the image shift amount into a defocus amount, and generate defocus map data representing the distribution of the defocus amount (distribution on a two-dimensional plane of the captured image). The distance acquirer 4 may acquire the distance map data of the distance to the object converted from the defocus amount.

[0185] The in-vehicle system 600 and the mobile device 700 may each include a notification device (notifier) ​​configured to notify the manufacturer of the in-vehicle system, the seller (dealer) of the mobile device, etc. of the fact that the mobile device 700 has collided with an obstacle. For example, the notification device may transmit information (collision information) related to the collision between the mobile device 700 and the obstacle to a preset external notification destination via e-mail, etc.

[0186] Thus, in the case where the collision information is automatically notified by the notification device, measures such as inspection and repair can be taken immediately after the collision. The notification destination of the collision information can be any destination set by the user, such as an insurance company, a medical institution, and a police department. The notification device can be configured so that not only the collision information but also the failure information of each component and the consumption information of consumables are notified. The presence or absence of a collision can be detected by using the distance information obtained based on the output from the camera unit 1 as described above or by other detectors (sensors).

[0187] In this description, the in-vehicle system 600 is applied to driving support (collision damage reduction), but the present invention is not limited to this example, and the in-vehicle system 600 is applicable to cruise control (including adaptive cruise control) and automatic driving. The in-vehicle system 600 is applicable not only to vehicles such as cars, but also to mobile bodies such as ships, aircraft, or industrial robots. It is applicable not only to mobile bodies, but also to various devices using object recognition such as intelligent transportation systems (ITS).

[0188] Other embodiments

[0189] The embodiments of the present invention may also be implemented by providing software (program) for performing the functions of the above-described embodiments to a system or device via a network or various storage media, and a computer or a central processing unit (CPU) or a microprocessing unit (MPU) of the system or device reads and executes the program.

[0190] Each example can provide an optical system having a sufficient angle of view and a sufficient imaging magnification in a central angle of view area, and make the imaging apparatus small.

[0191] While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

Claims

1. An optical system comprising a plurality of lenses and an aperture stop, It is characterized in that The projection characteristic y(θ) of the optical system indicating the relationship between the half viewing angle θ and the image height y on the image plane satisfies the following inequality: Wherein, θmax is the maximum half viewing angle of the optical system, and f is the focal length of the optical system, The differential value dy(θ) / dθ of the projection characteristic y(θ) at the half viewing angle θ has a local maximum.

2. The optical system according to claim 1, characterized in that The following inequality is satisfied: Here, θa is the half viewing angle at which the differential value dy(θ) / dθ has the local maximum value.

3. The optical system according to claim 1, characterized in that At a half viewing angle θ that is smaller than the half viewing angle θa at which the differential value dy(θ) / dθ has the local maximum and larger than the zero viewing angle, the following inequality is satisfied:

4. The optical system according to claim 1, characterized in that The following inequality is satisfied: where θb is the half viewing angle that satisfies the following equation:

5. The optical system according to claim 1, characterized in that At the maximum half viewing angle θmax, the following inequality is satisfied:

6. The optical system according to claim 1, characterized in that The plurality of lenses includes a first aspherical lens disposed on a magnification conjugate side of the aperture stop.

7. The optical system according to claim 6, characterized in that The first aspherical lens has a paraxial refractive power with a negative sign.

8. The optical system according to claim 6, characterized in that The first aspherical lens is a meniscus lens having a convex surface facing the magnification conjugate side.

9. The optical system according to claim 6, characterized in that The following inequalities are satisfied: Here, n1 is the refractive index of the first aspherical lens for the d-line.

10. The optical system according to claim 6, characterized in that The plurality of lenses includes a second aspherical lens disposed on a reduction conjugate side of the first aspherical lens.

11. The optical system according to claim 10, characterized in that The second aspherical lens has a positive paraxial refractive power.

12. The optical system according to claim 10, characterized in that The second aspherical lens is a meniscus lens having a convex surface facing the magnification conjugate side.

13. The optical system according to claim 10, characterized in that The following inequality is satisfied: Here, n1 is the refractive index of the first aspherical lens with respect to the d-line, and n2 is the refractive index of the second aspherical lens with respect to the d-line.

14. The optical system according to claim 10, characterized in that The first aspherical lens and the second aspherical lens each include an aspherical surface having an inflection point.

15. The optical system according to claim 14, characterized in that At least one of the aspherical surfaces of the first aspherical lens and the second aspherical lens includes a plurality of inflection points.

16. The optical system according to claim 1, characterized in that The following inequality is satisfied: Wherein, fa is the combined focal length of the lenses arranged on the magnification conjugate side of the aperture stop.

17. The optical system according to claim 1, characterized in that The lens closest to the reduction conjugate position among the plurality of lenses has a positive paraxial refractive power and a positive peripheral refractive power.

18. The optical system according to claim 1, characterized in that The following inequality is satisfied: Wherein, D is the distance on the optical axis from the aperture stop to the lens surface closest to the reduction conjugate position, and L is the distance on the optical axis from the lens surface closest to the magnification conjugate position to the lens surface closest to the reduction conjugate position.

19. The optical system according to claim 1, characterized in that The following inequality is satisfied:

20. A camera device, comprising: An optical system according to any one of claims 1 to 19; as well as An image sensor is configured to capture an image of an object via the optical system.

21. A vehicle-mounted system, comprising: The imaging device according to claim 20; as well as A determiner is configured to determine the possibility of a collision between the vehicle and the object based on the distance information of the object acquired from the camera device.

22. The vehicle-mounted system according to claim 21 further includes a control device, which is configured to output a control signal for generating a braking force on a drive unit of the vehicle when it is determined that there is a possibility of a collision between the vehicle and the object.

23. The in-vehicle system according to claim 21, further comprising a warning device configured to warn a user of the vehicle if it is determined that there is a possibility of a collision between the vehicle and the object. 24 . The in-vehicle system according to claim 21 , further comprising a notification device configured to notify a user of information related to the collision between the vehicle and the object.

25. A mobile device comprising the imaging device according to claim 20 and capable of moving while holding the imaging device. 26 . The mobile device according to claim 25 , further comprising a determiner configured to determine a possibility of a collision between a vehicle and the object based on the distance information of the object acquired from the camera device.

27. The mobile device according to claim 25, further comprising a control device configured to output a control signal for generating a braking force on a drive unit of the vehicle when it is determined that there is a possibility of a collision between the vehicle and the object.

28. The mobile device of claim 25, further comprising a warning device configured to warn a user of the vehicle if it is determined that there is a possibility of a collision between the vehicle and the object.

29. The mobile device of claim 25, further comprising a notification device configured to notify a user of information related to the collision between the vehicle and the object.

Images