Imaging lens system, camera module, vehicle-mounted system, and mobile object

Abstract

Provided are a compact, bright, and high-resolution imaging lens system, a camera module, a vehicle-mounted system, and a mobile object. An imaging lens system (11) comprises, in order from the object side to the image side: a first lens (L1) that has negative power and has an object-side surface having a convex surface facing the object side; a second lens (L2) that has negative power and has an image-side surface having a concave surface facing the image side; a third lens (L3) that has negative power and has an object-side surface having a concave surface facing the object side; a fourth lens (L4) that has positive power and has an object-side surface having a convex surface facing the object side; a stop STOP; a fifth lens (L5) that has positive power and has an image-side surface having a convex surface facing the image side; a sixth lens (L6) that has positive power and has an object-side surface having a convex surface facing the object side; a seventh lens (L7) that has negative power and has an image-side surface having a concave surface facing the image side; and an eighth lens (L8) that has positive power and has an object-side surface having a convex surface facing the object side. The imaging lens system satisfies 1.40< |F12 / F| < 1.55.

Description

Imaging lens systems, camera modules, in-vehicle systems, mobile objects

[0001] The present invention relates to an imaging lens system, a camera module, an in-vehicle system, and a moving body.

[0002] In recent years, vehicle-mounted cameras have been required to have sensing functions for detecting people and objects, and image sensors have been increasing in resolution and size. Accordingly, imaging lens systems mounted on vehicle-mounted cameras and the like have also tended to become larger. Meanwhile, due to the demand for omnidirectional sensing around the vehicle, vehicle-mounted cameras are increasingly being mounted in spatially limited locations, such as side mirrors. This has led to a demand for smaller vehicle-mounted cameras. Furthermore, a bright imaging lens system is required to realize the sensing function of vehicle-mounted cameras. Patent Document 1 describes an imaging optical system consisting of seven lenses.

[0003] JP 2018-081240 A

[0004] However, in the imaging optical system described in Patent Document 1, the diameter of the first lens is relatively large, making it difficult to sufficiently miniaturize the vehicle-mounted camera. Also, the F-number of the imaging optical system described in Patent Document 1 is 2.0, which means that the brightness of the imaging optical system is insufficient.

[0005] The present invention has been made in view of the above problems, and has an object to provide a compact, bright, high-resolution imaging lens system, camera module, in-vehicle system, and mobile body.

[0006] An imaging lens system according to one embodiment includes, in order from the object side to the image side, a first lens having a convex object-side surface facing the object side and negative power, a second lens having a concave image-side surface facing the image side and negative power, a third lens having a concave object-side surface facing the object side and negative power, a fourth lens having a convex object-side surface facing the object side and positive power, a stop, a fifth lens having a convex image-side surface facing the image side and positive power, a sixth lens having a convex object-side surface facing the object side and positive power, a seventh lens having a concave image-side surface facing the image side and negative power, and an eighth lens having a convex object-side surface facing the object side and positive power, wherein the imaging lens system satisfies the following conditional expression (1): 1.40<|F12 / F|<1.55 (1) where F is the focal length of the entire system and F12 is the combined focal length of the first and second lenses.

[0007] According to the present invention, it is possible to provide a compact, bright, and high-resolution imaging lens system, a camera module, an in-vehicle system, and a mobile object.

[0008] FIG. 1 is a cross-sectional view showing the configuration of a camera module and an imaging lens system according to Example 1. FIG. 2 is a diagram showing spherical aberration in the imaging lens system according to Example 1. FIG. 3 is a diagram showing astigmatism in the imaging lens system according to Example 1. FIG. 4 is a cross-sectional view showing the configuration of a camera module and an imaging lens system according to Example 2. FIG. 5 is a diagram showing spherical aberration in the imaging lens system according to Example 2. FIG. 6 is a diagram showing astigmatism in the imaging lens system according to Example 2. FIG. 7 is a cross-sectional view showing the configuration of a camera module and an imaging lens system according to Example 3. FIG. 8 is a diagram showing spherical aberration in the imaging lens system according to Example 3. FIG. 9 is a diagram showing astigmatism in the imaging lens system according to Example 3. FIG. 10 is a cross-sectional view showing the configuration of a camera module and an imaging lens system according to Example 4. FIG. 11 is a diagram showing spherical aberration in the imaging lens system according to Example 4. FIG. 12 is a cross-sectional view showing the configuration of a camera module and an imaging lens system according to Example 5. FIG. 13 is a diagram showing spherical aberration in the imaging lens system according to Example 5. FIG. 14 is an astigmatism diagram in the imaging lens system according to Example 5. FIG. 15 is a cross-sectional view showing the configuration of a camera module and an imaging lens system according to Example 6. FIG. 16 is a diagram showing spherical aberration in the imaging lens system according to Example 6. 13 is a diagram illustrating astigmatism in the imaging lens system of Example 6. FIG. 14 is a schematic diagram illustrating a vehicle on which an in-vehicle system including a camera module according to an embodiment of the present invention is mounted. FIG. 15 is a block diagram illustrating a configuration of an imaging device constituting the in-vehicle system of FIG.

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present embodiments can realize a highly reliable system, particularly in a sensing system, to ensure healthy lives and promote welfare for all people of all ages, and target "9.1 Develop quality, reliable, sustainable and resilient infrastructure, including regional and cross-border infrastructure, to support economic development and human well-being, with a focus on affordable and equitable access for all," in "9. Industry, innovation and infrastructure" of the Sustainable Development Goals (SDGs) advocated by the United Nations. (Embodiment 1: Imaging Lens System) The imaging lens system according to embodiment 1 includes, in order from the object side to the image side, a first lens having a convex object-side surface facing the object side and negative power, a second lens having a concave image-side surface facing the image side and negative power, a third lens having a concave object-side surface facing the object side and negative power, a fourth lens having a convex object-side surface facing the object side and positive power, a stop, a fifth lens having a convex image-side surface facing the image side and positive power, a sixth lens having a convex object-side surface facing the object side and positive power, a seventh lens having a concave image-side surface facing the image side and negative power, and an eighth lens having a convex object-side surface facing the object side, wherein the imaging lens system satisfies the following conditional expression (1): 1.40<|F12 / F|<1.55 (1)

[0010] This makes it possible to provide a compact, bright, and high-resolution imaging lens system. Specifically, when the imaging lens system satisfies conditional expression (1), the diameter of the first lens can be made sufficiently small while ensuring a sufficient angle of view, thereby enabling a compact imaging lens system. Furthermore, when the imaging lens system satisfies conditional expression (1), the occurrence of astigmatism, field curvature, and coma in the first lens and the second lens can be suppressed, enabling a high-resolution, bright imaging lens system to be realized. More specifically, when |F12 / F| is 1.40 or less, the diameter of the first lens can be made small, but the power of the first lens and the second lens becomes too strong, resulting in large astigmatism, field curvature, and coma. On the other hand, when |F12 / F| is 1.40 or less, the occurrence of astigmatism, field curvature, and coma can be suppressed, but the diameter of the first lens cannot be made sufficiently small because the power of the first lens and the second lens is too weak. The lower limit of |F12 / F| is more preferably 1.45 or 1.46, and even more preferably 1.47 or 1.48. The upper limit of |F12 / F| is more preferably 1.54 or 1.53, and even more preferably 1.52 or 1.51. Therefore, by making the imaging lens system satisfy conditional expression (1), it is possible to provide an imaging lens system that is compact, bright, and has high resolution.

[0011] Furthermore, when the combined focal length of the third and fourth lenses is defined as F34, the imaging lens system preferably satisfies the following conditional expression (2): 4.5<F34 / F<6.5 (2) By satisfying the above conditional expression (2), the occurrence of spherical aberration and coma can be suppressed, resulting in a high-resolution, bright imaging lens system. Specifically, if the value of F34 / F is 4.5 or less, the spherical aberration and coma generated in the third and fourth lenses become large, and the aberrations cannot be fully corrected by the lenses closer to the image than the fourth lens. Furthermore, if the value of F34 / F is 6.5 or more, the spherical aberration and coma generated in the third and fourth lenses are suppressed, but the power of the third and fourth lenses is too weak, resulting in a long overall optical length of the imaging lens system, making it difficult to achieve a compact imaging lens system. The overall optical length is the distance on the optical axis from the object-side surface of the first lens to the image plane of the imaging lens system. The lower limit of F34 / F is more preferably 4.6, 4.7, 4.8, 4.9, or 5.0, and even more preferably 5.1 or 5.2. The upper limit of F34 / F is more preferably 6.4, 6.3, or 6.2, and even more preferably 6.1 or 6.0.

[0012] Furthermore, when the composite focal length of the third lens and the fourth lens is defined as F34, it is preferable that the imaging lens system satisfy the following conditional expression (3): 0.20<|F12 / F34|<0.35 (3) When the imaging lens system satisfies the above conditional expression (3), it is possible to reduce the diameter of the first lens while suppressing the occurrence of spherical aberration, coma, astigmatism, and curvature of field. Specifically, when the value of |F12 / F34| is 0.20 or less, it is possible to reduce the diameter of the first lens, but the power of the first lens and the second lens becomes too strong compared to the power of the third lens and the fourth lens, making it impossible to sufficiently suppress the occurrence of spherical aberration, coma, astigmatism, and curvature of field, and these aberrations cannot be fully corrected by the lens closer to the image than the fourth lens. On the other hand, if the value of |F12 / F34| is 0.35 or greater, the occurrence of spherical aberration, coma, astigmatism, and field curvature can be suppressed, but the power of the first and second lenses becomes too weak compared to the power of the third and fourth lenses, making it impossible to sufficiently reduce the diameter of the first lens. The lower limit of |F12 / F34| is more preferably 0.21, 0.22, 0.23, or 0.24, and even more preferably 0.25 or 0.26. The upper limit of |F12 / F34| is more preferably 0.34, 0.33, 0.32, or 0.31, and even more preferably 0.30 or 0.29.

[0013] Furthermore, when the thickness of the center of the fourth lens is defined as T4 and the focal length of the fourth lens is defined as F4, it is preferable that the imaging lens system satisfies the following conditional expression (4): 0.2<T4 / F4<0.6 (4) When the imaging lens system satisfies the above conditional expression (4), it is possible to reduce the diameter of the first lens while suppressing manufacturing costs, and to suppress the occurrence of spherical aberration, coma aberration, and astigmatism in the fourth lens. Specifically, when the value of T4 / F4 is 0.2 or less, it is not possible to sufficiently reduce the diameter of the first lens, and further, the thinning of the thickness of the center of the fourth lens increases the curvature of the lens surface of the fourth lens, making it impossible to sufficiently suppress the occurrence of spherical aberration, coma aberration, and astigmatism in the fourth lens. Furthermore, if the value of T4 / F4 is 0.6 or more, this can contribute to reducing the diameter of the first lens, the curvature of the lens surface of the fourth lens can be reduced, and the occurrence of spherical aberration, coma aberration, and astigmatism in the fourth lens can be suppressed, but the thickness of the center of the fourth lens will be too thick, resulting in increased costs. The lower limit of T4 / F4 is more preferably 0.25, 0.30, or 0.35, and even more preferably 0.40. The upper limit of T4 / F4 is more preferably 0.55, 0.50, and even more preferably 0.45.

[0014] Furthermore, when the composite focal length of the lens group located closer to the image side than the aperture stop is defined as RGF, the imaging lens system preferably satisfies the following conditional expression (5): 3.0<RGF / F<4.0 (5) When the imaging lens system satisfies the above conditional expression (5), the overall optical length can be shortened and a sufficient back focus can be ensured. Here, back focus refers to the distance on the optical axis from the image-side surface of the lens located closest to the image side of the imaging lens system to the sensor surface. Specifically, by shortening the composite focal length RGF of the rear group, the distance between the conjugate points of the rear group is shortened, thereby shortening the overall optical length. More specifically, when the value of RGF / F is 3.0 or less, the overall optical length can be shortened but a sufficient back focus cannot be ensured. On the other hand, when the value of RGF / F is 4.0 or more, the back focus can be ensured but the overall optical length becomes long. The lower limit of RGF / F is more preferably 3.1, 3.2, or 3.3, and even more preferably 3.4. The upper limit of RGF / F is more preferably 3.9, 3.8, or 3.7, and even more preferably 3.6.

[0015] The third lens is preferably a meniscus lens, which can suppress the occurrence of spherical aberration, coma, and astigmatism in the third lens, thereby achieving a bright imaging lens system with high resolution.

[0016] (Embodiment 2: Camera Module) A camera module according to embodiment 2 includes the above-described imaging lens system and an imaging element that is disposed at the focal position of the imaging lens system and converts light condensed through the imaging lens system into an electrical signal. This makes it possible to provide a compact, bright, and high-resolution camera module.

[0017] Next, examples corresponding to the imaging lens system according to embodiment 1 and the camera module according to embodiment 2 will be described with reference to the drawings. (Example 1) Fig. 1 is a cross-sectional view showing the configuration of a camera module 10 according to example 1. Specifically, the camera module 10 includes an imaging lens system 11 and an imaging element 12. The imaging lens system 11 and the imaging element 12 are housed in a housing (not shown).

[0018] The imaging element 12 is an element that converts received light into an electrical signal, and is, for example, a CCD image sensor or a CMOS image sensor. The imaging element 12 is disposed at the image forming position (focal position) of the imaging lens system 11.

[0019] The imaging lens system 11 according to Example 1 includes, in order from the object side to the image side, a front group Gf including a first lens L1, a second lens L2, a third lens L3, and a fourth lens L4, an aperture stop (STOP), and a rear group Gr including a fifth lens L5, a sixth lens L6, a seventh lens L7, and an eighth lens L8. The image plane of the imaging lens system 11 is indicated by IMG. Note that an optical filter (such as an infrared transmission filter, a visible / infrared bandpass filter, or an infrared cut filter) is disposed between the imaging lens system 11 and the image sensor 12 as needed. In this specification, an example in which an infrared cut filter (IRCF) is disposed between the imaging lens system 11 and the image sensor 12 will be described.

[0020] The first lens L1 is a meniscus lens having negative power. The object-side surface S1 of the first lens L1 has a spherical shape with a convex surface facing the object side. The image-side surface S2 of the first lens L1 has a spherical shape with a concave surface facing the image side.

[0021] The second lens L2 is a meniscus lens having negative power. The object-side surface S3 of the second lens L2 has an aspheric shape with a convex surface facing the object side. The image-side surface S4 of the second lens L2 has an aspheric shape with a concave surface facing the image side.

[0022] The third lens L3 has negative power, an object-side surface S5 of the third lens L3 has a spherical shape with a concave surface facing the object side, and an image-side surface S6 of the third lens L3 has a spherical shape with a convex surface facing the image side.

[0023] The fourth lens L4 has positive power. The object-side surface S7 of the fourth lens L4 has a spherical shape with a convex surface facing the object side. The image-side surface S8 of the fourth lens L4 also has a spherical shape with a convex surface facing the image side.

[0024] The aperture stop STOP is an aperture that determines the F-number (F-number, Fno) of the lens system, and is disposed between the fourth lens L4 and the fifth lens L5.

[0025] The fifth lens L5 has positive power. The object-side surface S10 of the fifth lens L5 has an aspheric shape with a convex surface facing the object side. The image-side surface S11 of the fifth lens L5 also has an aspheric shape with a convex surface facing the image side.

[0026] The sixth lens L6 has positive power. The object-side surface S12 of the sixth lens L6 has a spherical shape with a convex surface facing the object side. The image-side surface S13 of the sixth lens L6 also has a spherical shape with a convex surface facing the image side.

[0027] The seventh lens L7 has negative power, an object-side surface S13 of the seventh lens L7 has a spherical shape with a concave surface facing the object side, and an image-side surface S14 of the seventh lens L7 has a spherical shape with a concave surface facing the image side.

[0028] The sixth lens L6 and the seventh lens L7 form a cemented lens. That is, the image-side surface S13 of the sixth lens L6 and the object-side surface S13 of the seventh lens L7 are in contact with each other. The sixth lens L6 and the seventh lens L7 are cemented together with an adhesive layer of a predetermined thickness.

[0029] The eighth lens L8 has positive power. The object-side surface S15 of the eighth lens L8 has an aspheric shape with a convex surface facing the object side. The image-side surface S16 of the eighth lens L8 also has an aspheric shape with a convex surface facing the image side.

[0030] The infrared cut filter (IRCF) is a filter for cutting light in the infrared region. When designing the imaging lens system 11, the infrared cut filter is treated as an integral part of the imaging lens system 11. However, the infrared cut filter is not an essential component of the imaging lens system 11. The infrared cut filter is disposed on the image side of the eighth lens L8. Furthermore, a sensor cover glass may be disposed between the infrared cut filter and the imaging element 12 to prevent dust from adhering to the imaging element 12.

[0031] Table 1 shows lens data for each lens surface in the imaging lens system 11 of Example 1. Table 1 presents the lens data, such as the radius of curvature (mm) of each surface, the surface spacing (mm) on the optical axis OA, the refractive index nd for the d-line, and the Abbe number vd for the d-line. In Table 1, surfaces marked with an asterisk (*) are aspherical. In addition, the imaging lens system 11 of Example 1 has an F-number of 1.6 and a total angle of view of 196°.

[0032]

[0033] The aspherical shape adopted for the lens surface is as follows: Z is the sag amount, c is the inverse of the radius of curvature, k is the conic coefficient, r is the height from the optical axis OA, and the aspherical coefficients of the 4th, 6th, 8th, 10th, 12th, 14th, and 16th orders are respectively α ４ , α ６ , α ８ , α １０ , α １２ , α １４ , α １６ When this is the case, it is expressed by the following equation:

[0034] Table 2 shows aspherical coefficients for defining the aspherical shape of the aspherical lens surface in the imaging lens system 11 of Example 1. In Table 2, for example, "-4.53197E-05" corresponds to "-4.53197×10 －５ The same applies to the numerical expressions in the following tables.

[0035]

[0036] Next, aberrations will be described using the drawings. FIGS. 2A and 2B show spherical aberration and astigmatism diagrams for the imaging lens system 11 of Example 1. In the longitudinal aberration diagram of FIG. 2A, the horizontal axis indicates the position where a ray intersects with the optical axis OA, and the vertical axis indicates the passing height (relative value) of the ray on the entrance pupil. FIG. 2A also shows simulation results for the e-line, C'-line, and F'-line. In the astigmatism diagram of FIG. 2B, the horizontal axis indicates the distance in the direction of the optical axis OA, and the vertical axis indicates the angle of view. In the astigmatism diagram of FIG. 2B, Sag shift indicates the imaging position of a sagittal ray bundle, and Tan shift indicates the imaging position of a tangential ray bundle. FIG. 2B also shows simulation results for the e-line.

[0037] 3 is a cross-sectional view showing a camera module 10 according to Example 2. The configuration of the imaging lens system 11 according to Example 2 is the same as that of Example 1, and therefore a description thereof will be omitted. Below, characteristic data of the imaging lens system 11 according to Example 2 will be described.

[0038] Table 3 shows lens data for each lens surface of the imaging lens system 11 according to Example 2. The items shown in Table 3 are the same as those in Table 1, and therefore their explanation will be omitted. Furthermore, the imaging lens system 11 according to Example 2 has an F-number of 1.6 and a total angle of view of 196°.

[0039]

[0040] Table 4 shows aspherical coefficients for defining the aspherical shape of the aspherical lens surface in the imaging lens system 11 of Example 2. In Table 4, the aspherical shape adopted for the lens surface is expressed by the same formula as in Example 1.

[0041]

[0042] 4A and 4B show spherical aberration diagrams and astigmatism diagrams for the imaging lens system 11 of Example 2. The explanations for the aberration diagrams shown in Figs. 4A and 4B are the same as those for Figs. 2A and 2B, and therefore will not be repeated.

[0043] 5 is a cross-sectional view showing a camera module 10 according to Example 3. The imaging lens system 11 according to Example 3 has the same lens configuration as that of Example 1, and therefore its description will be omitted. The characteristic data of the imaging lens system 11 according to Example 3 will be described below.

[0044] Table 5 shows lens data for each lens surface of the imaging lens system 11 according to Example 3. The items shown in Table 5 are the same as those in Table 1, and therefore their explanation will be omitted. Furthermore, the imaging lens system 11 according to Example 3 has an F-number of 1.6 and a total angle of view of 196°.

[0045]

[0046] Table 6 shows aspherical coefficients for defining the aspherical shape of the aspherical lens surface in the imaging lens system 11 of Example 3. In Table 6, the aspherical shape adopted for the lens surface is expressed by the same formula as in Example 1.

[0047]

[0048] 6A and 6B show spherical aberration diagrams and astigmatism diagrams for the imaging lens system 11 of Example 3. The explanations for the aberration diagrams shown in Figs. 6A and 6B are the same as those for Figs. 2A and 2B, and therefore will not be repeated.

[0049] Example 4 Fig. 7 is a cross-sectional view showing a camera module 10 according to Example 4. In the imaging lens system 11 according to Example 4, the object side surface S10 of the fifth lens L5 has a spherical shape with a convex surface facing the object side, and the image side surface S11 of the fifth lens L5 has a spherical shape with a convex surface facing the image side. Since the configuration of the imaging lens system 11 according to Example 4 other than the fifth lens L5 is the same as that of Example 1, a description thereof will be omitted. Below, characteristic data of the imaging lens system 11 according to Example 4 will be described.

[0050] Table 7 shows lens data for each lens surface of the imaging lens system 11 according to Example 4. The items shown in Table 7 are the same as those in Table 1, and therefore their explanation will be omitted. Furthermore, the imaging lens system 11 of Example 4 has an F-number of 1.6 and a total angle of view of 196°.

[0051]

[0052] Table 8 shows aspherical coefficients for defining the aspherical shape of the aspherical lens surface in the imaging lens system 11 of Example 4. In Table 8, the aspherical shape adopted for the lens surface is expressed by the same formula as in Example 1.

[0053]

[0054] 8A and 8B show spherical aberration diagrams and astigmatism diagrams for the imaging lens system 11 of Example 4. The explanations for the aberration diagrams shown in Figs. 8A and 8B are the same as those for Figs. 2A and 2B, and therefore will not be repeated.

[0055] Example 5 Fig. 9 is a cross-sectional view showing a camera module 10 according to Example 5. In the imaging lens system 11 according to Example 5, the object-side surface S15 of the eighth lens L8 has an aspherical shape with a convex surface facing the object side, and the image-side surface S16 of the eighth lens L8 has a spherical shape with a convex surface facing the image side. Since the configuration of the imaging lens system 11 according to Example 5 other than the eighth lens L8 is the same as that of Example 4, a description thereof will be omitted. Below, characteristic data of the imaging lens system 11 according to Example 4 will be described.

[0056] Table 9 shows lens data for each lens surface of the imaging lens system 11 according to Example 5. The items shown in Table 9 are the same as those in Table 1, and therefore their explanation will be omitted. Furthermore, the imaging lens system 11 according to Example 5 has an F-number of 1.6 and a total angle of view of 196°.

[0057]

[0058] Table 10 shows aspherical coefficients for defining the aspherical shape of the aspherical lens surface in the imaging lens system 11 of Example 5. In Table 10, the aspherical shape adopted for the lens surface is expressed by the same formula as in Example 1.

[0059]

[0060] 10A and 10B show diagrams of spherical aberration and astigmatism in the imaging lens system 11 of Example 5. The explanations for the aberration diagrams shown in Figs. 10A and 10B are the same as those for Figs. 2A and 2B, and therefore will not be repeated.

[0061] 11 is a cross-sectional view showing a camera module 10 according to Example 6. The configuration of the imaging lens system 11 according to Example 6 is the same as that of Example 4, and therefore a description thereof will be omitted. Below, characteristic data of the imaging lens system 11 according to Example 6 will be described.

[0062] Table 11 shows lens data for each lens surface of the imaging lens system 11 according to Example 6. The items shown in Table 11 are the same as those in Table 1, and therefore their explanation will be omitted. Furthermore, the imaging lens system 11 of Example 6 has an F-number of 1.6 and a total angle of view of 196°.

[0063]

[0064] Table 12 shows aspherical coefficients for defining the aspherical shape of the aspherical lens surface in the imaging lens system 11 of Example 6. In Table 12, the aspherical shape adopted for the lens surface is expressed by the same formula as in Example 1.

[0065]

[0066] 12A and 12B show diagrams of spherical aberration and astigmatism in the imaging lens system 11 of Example 6. The explanations for the aberration diagrams shown in Figs. 12A and 12B are the same as those for Figs. 2A and 2B, and therefore will not be repeated.

[0067] Table 13 shows the focal length F of the entire optical system of the imaging lens system 11, the focal length F1 of the first lens L1, the focal length F2 of the second lens L2, the focal length F3 of the third lens L3, the focal length F4 of the fourth lens L4, the focal length F5 of the fifth lens L5, the focal length F6 of the sixth lens L6, the focal length F7 of the seventh lens L7, the focal length F7 of the eighth lens L8, the value of |F12 / F|, the value of F34 / F, the value of |F12 / F34|, the value of T4 / F4, and RGF / F. In Table 13, the focal lengths and thicknesses are in mm. The focal lengths shown in Table 13 were calculated using the e-line.

[0068]

[0069] In Examples 1 to 6, the imaging lens system 11 satisfies conditional expression (1), thereby providing a compact, bright, and high-resolution imaging lens system. Specifically, in Examples 1 to 6, various aberrations can be suitably reduced as shown in FIGS. 2A, 2B, 4A, 4B, 6A, 6B, 8A, 8B, 10A, 10B, 12A, and 12B. Therefore, in Examples 1 to 6, the imaging lens system 11 has high resolution. Furthermore, in Examples 1 to 6, the total angle of view is 196°, and the imaging lens system 11 has a wide angle of view that is sufficiently wide for vehicle sensing. Furthermore, in Examples 1 to 6, the F-number is 1.6, and the imaging lens system 11 has sufficient brightness for vehicle sensing, including at night.

[0070] Furthermore, in Examples 1 to 6, by the imaging lens system 11 satisfying conditional expression (2), it is possible to suppress the occurrence of spherical aberration and coma aberration, and to realize a high-resolution, bright imaging lens system. In fact, in Examples 1 to 6, various aberrations can be suitably reduced, as shown in Figures 2A, 2B, 4A, 4B, 6A, 6B, 8A, 8B, 10A, 10B, 12A, and 12B.

[0071] Furthermore, in Examples 1 to 6, the imaging lens system satisfies conditional expression (3), so that the diameter of the first lens L1 can be reduced while suppressing the occurrence of spherical aberration, coma, astigmatism, and curvature of field. In fact, in Examples 1 to 6, various aberrations can be suitably reduced, as shown in Figures 2A, 2B, 4A, 4B, 6A, 6B, 8A, 8B, 10A, 10B, 12A, and 12B.

[0072] Furthermore, in Examples 1 to 6, by the imaging lens system 11 satisfying conditional expression (4), it is possible to reduce the diameter of the first lens L1 while suppressing manufacturing costs, and it is also possible to suppress the occurrence of spherical aberration, coma aberration, and astigmatism in the fourth lens L4. In fact, in Examples 1 to 6, various aberrations can be suitably reduced, as shown in Figures 2A, 2B, 4A, 4B, 6A, 6B, 8A, 8B, 10A, 10B, 12A, and 12B.

[0073] Furthermore, in Examples 1 to 6, the imaging lens system 11 satisfies conditional expression (5), so that the total optical length can be shortened and a sufficient back focus can be ensured.

[0074] Furthermore, in Examples 1 to 6, the third lens L3 is a meniscus lens, which suppresses the occurrence of spherical aberration, coma aberration, and astigmatism in the third lens L3, thereby realizing a bright imaging lens system with high resolution. In fact, in Examples 1 to 6, various aberrations can be suitably reduced, as shown in Figures 2A, 2B, 4A, 4B, 6A, 6B, 8A, 8B, 10A, 10B, 12A, and 12B.

[0075] Furthermore, by providing the camera module 10 with the imaging lens system 11, it is possible to provide a compact, bright, and high-resolution camera module 10.

[0076] Third Embodiment FIG. 13 is a schematic diagram of a vehicle 40 equipped with an in-vehicle system including an imaging device 50 including an imaging lens system 11 according to the first or second embodiment and an imaging element 12 that converts light collected through the imaging lens system 11 into an electrical signal. As shown in the figure, the imaging device 50 can be mounted on the vehicle 40, and FIG. 13 is an example of an arrangement illustrating the mounting position of the imaging device 50 on the vehicle 40. The imaging device 50 mounted on the vehicle 40 can also be called an in-vehicle camera and can be installed in various locations on the vehicle 40. For example, the first imaging device 50a may be disposed on or near the front bumper as a camera that monitors the front of the vehicle 40 while the vehicle 40 is traveling. The second imaging device 50b that monitors the front of the vehicle 40 may be disposed near an inner rearview mirror inside the vehicle 40. The third imaging device 50c may be disposed on the dashboard, in the instrument panel, or the like as a camera that monitors the driver's driving status. The fourth imaging device 50d may be installed at the rear of the vehicle 40 to monitor the rear of the vehicle 40. The imaging devices 50a and 50b can be called front cameras. The third imaging device 50c can be called an in-camera. The fourth imaging device 50d can be called a rear camera. The imaging device 50 is not limited to these, and includes imaging devices installed in various positions, such as a left side camera that images the left rear side and a right side camera that images the right rear side.

[0077] Image signals of images captured by the imaging device 50 may be output to an information processing device 42 and / or a display device 43 within the vehicle 40. The information processing device 42 and the display device 43, together with the imaging device 50, constitute an in-vehicle system. The information processing device 42 within the vehicle 40 includes a device that processes image signals acquired by the imaging device 50 and recognizes various objects in the captured images to assist the driver in driving. Examples of the information processing device 42 include, but are not limited to, a navigation system, a collision damage mitigation braking system, a vehicle-to-vehicle distance control system, and a lane departure warning system. The display device 43 displays images processed and output by the information processing device 42, but can also receive image signals directly from the imaging device 50. The display device 43 may be, but is not limited to, a liquid crystal display (LCD), an organic electroluminescence (EL) display, or an inorganic EL display. The display device 43 can display image signals output from the imaging device 50, which captures images from positions difficult for the driver to view, such as a rear camera, to occupants such as the driver.

[0078] Fig. 14 shows the configuration of an imaging device 50 that constitutes the in-vehicle system of Fig. 13. As shown in the figure, the imaging device 50 according to one embodiment includes a control unit 52, a storage unit 54, and a camera module 10.

[0079] The control unit 52 controls the camera module 10 and processes the electrical signals output from the image sensor 12 of the camera module 10. The control unit 52 may be configured as, for example, a processor. The control unit 52 may also include one or more processors. The processor may include a general-purpose processor that loads a specific program to execute a specific function, and a dedicated processor specialized for a specific process. The dedicated processor may include an application-specific integrated circuit (IC). An application-specific IC is also called an application-specific integrated circuit (ASIC). The processor may include a programmable logic device. A programmable logic device is also called a programmable logic device (PLD). A PLD may include a field-programmable gate array (FPGA). The control unit 52 may be either a system-on-a-chip (SoC) or a system-in-a-package (SiP) in which one or more processors work together.

[0080] The storage unit 54 stores various information or parameters related to the operation of the imaging device 50. The storage unit 54 may be configured with, for example, a semiconductor memory or the like. The storage unit 54 may function as a work memory for the control unit 52. The storage unit 54 may store captured images. The storage unit 54 may store various parameters, etc., used by the control unit 52 to perform detection processing based on the captured images. The storage unit 54 may be included in the control unit 52.

[0081] As described above, the camera module 10 captures an image of a subject formed via the imaging lens system 11 with the imaging element 12 and outputs the captured image. The image captured by the camera module 10 is also referred to as a captured image.

[0082] The imaging element 12 may be configured, for example, as a CMOS (Complementary Metal Oxide Semiconductor) image sensor or a CCD (Charge Coupled Device). The imaging element 12 has an imaging surface on which a plurality of pixels are arranged. Each pixel outputs a signal specified by a current or voltage according to the amount of incident light. The signal output by each pixel is also referred to as imaging data.

[0083] The imaging data may be read by the camera module 10 for all pixels and captured by the control unit 52 as a captured image. A captured image read by all pixels is also referred to as a maximum captured image. The imaging data may be read by the camera module 10 for some pixels and captured as a captured image. In other words, the imaging data may be read from pixels in a predetermined capture range. The imaging data read from pixels in the predetermined capture range may be captured as a captured image. The predetermined capture range may be set by the control unit 52. The camera module 10 may acquire the predetermined capture range from the control unit 52. The imaging element 12 may capture an image of a predetermined capture range from the subject image formed via the imaging lens system 11.

[0084] It should be noted that the present invention is not limited to the above-described embodiments, and modifications can be made as appropriate without departing from the spirit of the present invention. For example, the applications of the imaging lens system of the present invention are not limited to vehicle-mounted cameras and surveillance cameras, and it can also be used for other purposes, such as being mounted on small electronic devices such as mobile phones.

[0085] This application claims priority based on Japanese Patent Application No. 2024-111615, filed July 11, 2024, the disclosure of which is incorporated herein in its entirety by reference.

[0086] It is possible to provide a compact, bright, high-resolution imaging lens system, a camera module, an in-vehicle system, and a mobile object.

[0087] REFERENCE SIGNS LIST 10 camera module 11 imaging lens system 12 imaging element 40 vehicle (moving body) 42 information processing device (processing device) 43 display device (output device) 50 imaging device 52 control unit L1 first lens L2 second lens L3 third lens L4 fourth lens L5 fifth lens L6 sixth lens L7 seventh lens L8 eighth lens STOP aperture Gf front group Gr rear group IRCF infrared cut filter IMG imaging surface OA optical axis

Claims

1. An imaging lens system comprising, in order from the object side to the image side, a first lens having a convex object-side surface facing the object side and negative power, a second lens having a concave image-side surface facing the image side and negative power, a third lens having a concave object-side surface facing the object side and negative power, a fourth lens having a convex object-side surface facing the object side and positive power, a stop, a fifth lens having a convex image-side surface facing the image side and positive power, a sixth lens having a convex object-side surface facing the object side and positive power, a seventh lens having a concave image-side surface facing the image side and negative power, and an eighth lens having a convex object-side surface facing the object side and positive power, wherein when the focal length of the entire imaging lens system is defined as F and the combined focal length of the first and second lenses is defined as F12, the following conditional expression (1) is satisfied: 1.40<|F12 / F|<1.55 (1) 2. The imaging lens system according to claim 1, wherein when the composite focal length of the third lens and the fourth lens is defined as F34, the following conditional expression (2) is satisfied: 4.5<F34 / F<6.5 (2) 3. The imaging lens system according to claim 1, wherein when the composite focal length of the third lens and the fourth lens is defined as F34, the following conditional expression (3) is satisfied: 0.20<|F12 / F34|<0.35 (3) 4. The imaging lens system according to claim 1, wherein the following conditional expression (4) is satisfied when the thickness of the center of the fourth lens is defined as T4 and the focal length of the fourth lens is defined as F4: 0.2<T4 / F4<0.6 (4) 5. The imaging lens system according to claim 1, wherein the following conditional expression (5) is satisfied when the composite focal length of the lens group located on the image side of the aperture stop is defined as RGF: 3.0<RGF / F<4.0 (5) 6. The imaging lens system according to claim 1, wherein the third lens is a meniscus lens.

7. A camera module comprising the imaging lens system according to any one of claims 1 to 6 and an imaging element that converts light collected through said imaging lens system into an electrical signal.

8. An in-vehicle system to be mounted on a vehicle, comprising: a camera module according to claim 7; and an information processing device that processes an image output from the imaging element of the camera module and recognizes an object in the image.

9. A mobile body equipped with the on-board system described in claim 8, wherein the on-board system further comprises an output device that outputs information to an occupant, and the information processing device is configured to output the recognition information of the object to the output device.

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