Imaging lens system and camera module, imaging device, in-vehicle system, mobile device equipped therewith

Abstract

To provide a compact imaging lens system with improved imaging performance and high resolution. [Solution] The device comprises, in order from the object side toward the image side, a first lens having negative power with the object side facing convex toward the object and the image side facing concave toward the image; a second lens having negative power with the image side facing concave toward the image; a third lens having positive power with the image side facing convex toward the image; an aperture; a fourth lens having positive power with the image side facing convex toward the image; a fifth lens; and a sixth lens, wherein the fifth and sixth lenses are cemented lenses, and the second lens has the object side facing concave toward the object.

Description

Technical Field

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

Background Art

[0002] In recent years, an imaging lens system for in-vehicle use has been required to have a lens corresponding to a wide viewing angle. The imaging lens system for in-vehicle use is used for an in-vehicle camera, and for example, it is used for view applications such as front, back, and side for ensuring safety when driving a vehicle, and for sensing applications.

[0003] The imaging lens system of the in-vehicle camera is also required to be an imaging lens system having high brightness and high resolution. Further, an in-vehicle camera mounted on a side mirror or the like of an automobile (vehicle) is required to be small, lightweight, inexpensive, and have high resolution that can be used in a wide temperature range because it is mounted in a narrow space close to the outside air.

[0004] In addition, the imaging lens system is required to have high resolution with improved imaging performance by increasing the image circle radius where the image of the captured subject is circularly projected onto the surface of the imaging element and the image height as the height from the optical axis.

[0005] On the other hand, when the imaging lens system shortens and miniaturizes the overall length of the optical system and increases the image circle radius and the like to improve the imaging performance, magnification chromatic aberration and coma aberration occur, and it has been difficult to obtain high resolution. Patent Document 1 describes an imaging lens system in an in-vehicle camera.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] The present invention has been made in view of the above, and provides an imaging lens system with a wide angle of view of about 90°, a compact size, and high resolution with improved imaging performance. [Means for solving the problem]

[0008] The system comprises, in order from the object side toward the image side, a first lens having negative power with the object side facing convex toward the object and the image side facing concave toward the image side; a second lens having negative power with the image side facing concave toward the image side; a third lens having positive power with the image side facing convex toward the image side; an aperture; a fourth lens having positive power with the image side facing convex toward the image side; a fifth lens; and a sixth lens, wherein the fifth and sixth lenses are cemented lenses, and the second lens has the object side facing concave toward the object side. [Effects of the Invention]

[0009] This invention provides a compact imaging lens system with improved imaging performance and high resolution. [Brief explanation of the drawing]

[0010] [Figure 1] This is a cross-sectional view of the imaging lens system according to Example 1. [Figure 2A] This is a spherical aberration diagram of the imaging lens system according to Example 1. [Figure 2B] This is an image field curvature diagram of the imaging lens system according to Example 1. [Figure 2C] This is a distortion aberration diagram of the imaging lens system according to Example 1. [Figure 3] This is a cross-sectional view of the imaging lens system according to Example 2. [Figure 4A] This is a spherical aberration diagram of the imaging lens system according to Example 2. [Figure 4B] This is an image field curvature diagram of the imaging lens system according to Example 2. [Figure 4C] This is a distortion aberration diagram of the imaging lens system according to Example 2. [Figure 5]It is a cross-sectional view of an imaging lens system according to Embodiment 3. [Figure 6A] It is a spherical aberration diagram of the imaging lens system according to Embodiment 3. [Figure 6B] It is a field curvature diagram of the imaging lens system according to Embodiment 3. [Figure 6C] It is a distortion aberration diagram of the imaging lens system according to Embodiment 3. [Figure 7] It is a configuration diagram of an imaging device including an imaging lens system. [Figure 8] It is a schematic diagram of a vehicle including an imaging device. [Figure 9] It is a configuration diagram of a vehicle including an imaging device.

Mode for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present invention will be described with reference to the drawings and the like. In the drawings and explanations of this embodiment, functionally identical elements may sometimes be denoted by the same reference numerals. Note that the following explanations show embodiments based on principles, but these are for understanding this embodiment and are not used to interpret this embodiment in a limiting manner. The description of this embodiment is merely a typical example and does not limit the claims or application examples in any sense.

[0012] Although this embodiment is described in sufficient detail for those skilled in the art to implement, other embodiments are also possible, and it is necessary to understand that changes in configuration and structure and replacement of various elements are possible without departing from the scope and spirit of the technical idea. Therefore, the following explanations should not be construed in a limiting manner.

[0013] In addition, this embodiment can realize a highly reliable system particularly in a sensing system, aiming to construct a resilient infrastructure, promote inclusive and sustainable industrialization, and drive innovation, targeting "9: Build the infrastructure for industry and technological innovation" and "9.1: Develop high-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 people." of the Sustainable Development Goals (SDGs) proposed by the United Nations. [Embodiment 1] Hereinafter, based on the embodiments of the present invention, an imaging lens system according to the present invention, a camera module, an imaging device, an in-vehicle system, and a moving body including the same will be described in detail with reference to the drawings.

[0014] FIG. 1 is an example of the first embodiment and also relates to Example 1 based on specific numerical values. Before describing the examples including specific numerical values, first, the principle embodiments of the present invention will be described.

[0015] When the radius of curvature of the lens surface S3 on the object side of the second lens L2 is L2R1 and the focal length of the entire optical system is f, the imaging lens system 11 satisfies the following conditional expression (1). -1.7 < L2R1 / f < -1.5 ···(1) By satisfying the conditional expression (1), it is possible to provide an imaging lens system that is small in size, has improved imaging performance, and further has higher resolution.

[0016] When the minimum sag amount of the lens surface S3 on the object side of the second lens L2 is "min sagL2R1" and the focal length of the entire optical system is f, the imaging lens system 11 satisfies the following conditional expression (2). -0.35 < min sagL2R1 / f < -0.18 ···(2) By satisfying the conditional expression (2), the imaging performance can be improved by increasing the image circle radius or shortening the overall length of the optical system. Thereby, it is possible to provide an imaging lens system that is small in size, has improved imaging performance, and further has higher resolution.

[0017] The imaging lens system 11 satisfies the following condition (3) when the maximum sag amount of the lens surface S14, which is the image side of the sixth lens L6, is "max sagL6R2", and the total optical length along the optical axis O from the object-side lens surface S1 of the first lens L1 to the imaging surface S19 of the image sensor 12 is TTL. |max sagL6R2 / TTL|<0.004 ···(3) By satisfying condition (3), it is possible to provide an imaging lens system that is compact, has improved imaging performance, and possesses even higher resolution.

[0018] The imaging lens system 11 satisfies the following condition (4) when the focal length of the third lens L3 is f3 and the focal length of the fourth lens L4 is f4. 1.1 <f3 / f4<1.3 ···(4) By satisfying condition (4), it is possible to provide an imaging lens system that is compact, has improved imaging performance, and possesses even higher resolution.

[0019] The imaging lens system 11 satisfies the following condition (5) when the focal length of the second lens L2 is f2 and the focal length of the entire optical system is f. -3.0 <f2 / f<-2.0 ···(5) By satisfying condition (5), it is possible to provide an imaging lens system that is compact, has improved imaging performance, and possesses even higher resolution.

[0020] The imaging lens system 11 satisfies the following condition (6) when the focal length of the third lens L3 is f3 and the focal length of the entire optical system is f. 2.0 <f3 / f<3.0 ···(6) By satisfying condition (6), it is possible to provide a compact imaging lens system with improved imaging performance and even higher resolution.

[0021] The imaging lens system 11 satisfies the following condition (8) when the horizontal angle of view (full angle) is 2ω. 160<2ω ···(8) By satisfying condition (8), it is possible to provide a compact imaging lens system with improved imaging performance and even higher resolution.

[0022] As an embodiment, the imaging lens system 11 of the camera module 10 will be described as an example including specific numerical values.

[0023] [Example 1] Figure 1 is a cross-sectional view showing the lens configuration of the imaging lens system 11 of the camera module 10 of Embodiment 1. As shown in Figure 1, Embodiment 1 consists of six lenses. The imaging lens system 11 of Embodiment 1 comprises a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, and a sixth lens L6, in the order of the optical axis O direction from the object side toward the image side.

[0024] Furthermore, the imaging lens system 11 includes a front lens group that determines the angle of view characteristics, etc., through the first lens L1, the second lens L2, and the third lens L3. In addition, the imaging lens system 11 has a front lens group and a rear lens group that contributes to brightness, light-gathering characteristics, etc., through the fourth lens L4, the fifth lens L5, and the sixth lens L6, flanking the optical aperture 1.

[0025] The first lens L1 has a lens surface S1 which is the object side of a spherical surface with positive curvature and a convex shape toward the object, and a lens surface S2 which is the image side of a spherical surface with positive curvature and a concave shape toward the image. That is, the object side faces convex toward the object, and the image side faces concave toward the image. The first lens L1 is a negative lens with a negative power (negative refractive power) that diffuses light rays, and is a meniscus-shaped glass lens with a thicker edge than the center.

[0026] The second lens L2 has an aspherical lens surface S3 with negative curvature and a concave shape on the object side, and an aspherical lens surface S4 with positive curvature and a concave shape on the image side. The second lens L2 is a negative lens with negative power and is made of plastic.

[0027] The third lens L3 has an aspherical lens surface S5 with positive curvature that is convex toward the object side, and an aspherical lens surface S6 with negative curvature that is convex toward the paraxial side toward the image side. The third lens L3 is a positive lens made of plastic, with a positive power where light rays converge, and is thicker towards the center than towards the edges. The distance between the lenses is narrower than the distance between lens surfaces S2 and S3 due to the concave shape of the lens surface S4 of the second lens L2 and the convex shape of the lens surface S5 of the third lens L3. In addition, the front group of lenses from the first lens L1 to the third lens L3 produces light rays that are close to afocal, with the light rays emitting almost parallel.

[0028] The optical aperture 1 (STOP) has an opening that allows light rays to pass through the optical aperture surface S7 on the object side and the optical aperture surface S8 on the image side, and the amount of light rays is set by the aperture diameter. The optical aperture 1 is made of a non-transparent material and has a thin shape.

[0029] The fourth lens L4 has a spherical lens surface S9 with positive curvature that is convex toward the object side, and a spherical lens surface S10 with negative curvature that is convex toward the image side. The fourth lens L4 is a positive lens with positive power and is made of glass. Thus, the third lens L3 and the fourth lens L4 are positive lenses, and the optical aperture 1 is installed between the third lens L3 and the fourth lens L4.

[0030] The fifth lens L5 has an aspherical lens surface S11 with positive curvature and a convex shape on the object side, and an aspherical lens surface S12 with positive curvature and a concave shape on the image side. The fifth lens L5 is a negative lens with negative power and is a meniscus-shaped plastic lens.

[0031] The sixth lens L6 has an aspherical lens surface S13 with positive curvature and a convex shape toward the object side, and an aspherical lens surface S14 with positive curvature and a concave shape toward the paraxial side toward the image side. The sixth lens L6 is a positive lens with positive power and is a meniscus-shaped plastic lens.

[0032] Furthermore, the image-side lens surface S12 of the fifth lens L5 is bonded to the object-side lens surface S13 of the sixth lens L6 by applying a synthetic resin adhesive or the like, forming a cemented lens with the fifth lens L5 and the sixth lens L6. This cemented lens has a gentle negative power.

[0033] Furthermore, lens surface S14 has a larger absolute radius of curvature than lens surfaces S11, S12, and S13, making it nearly flat. Also, the radii of curvature of the joined lens surfaces S12 and S13 are the same, and their absolute radii of curvature are smaller than those of lens surfaces S11, S14, and the other lens surfaces.

[0034] Furthermore, the area around the joint and edges of the cemented lenses may be coated with a solvent-free resin mixed with carbon black or the like. The fifth lens L5 and the sixth lens L6 can be combined to correct aberrations.

[0035] Furthermore, in the lens system from the first lens L1 to the sixth lens L6, the distance between the first lens L1 and the second lens L2 is wider than the distance between other adjacent lenses.

[0036] The first lens L1 and the fourth lens L4 are glass lenses with excellent heat resistance and weather resistance, and can withstand natural outdoor environments such as sunlight, temperature, humidity, and rain, suppressing focus fluctuations due to changes in ambient temperature. The lens surface S1 of the first lens L1 may be coated with a water-repellent or water-resistant coating.

[0037] Furthermore, the second lens L2, third lens L3, fifth lens L5, and sixth lens L6 are made of plastic to achieve weight reduction, cost reduction, and impact resistance. At least one of the second lens L2, third lens L3, fifth lens L5, and sixth lens L6 may be a plastic lens.

[0038] Furthermore, each lens surface of the first lens L1 to the sixth lens L6 may have a curved surface at least on the side passing through the optical axis O, similar to the lens surface S2 of the first lens L1, and its edges may be flat.

[0039] Thus, the imaging lens system 11 comprises, in order from the object side to the image side, a first lens L1 having negative power with its object side (lens surface S1) facing convex toward the object and its image side (lens surface S2) facing concave toward the image side; a second lens L2 having negative power with its image side (lens surface S4) facing concave toward the image side; a third lens L3 having positive power with its image side (lens surface S6) facing convex toward the image side; an optical aperture 1; a fourth lens L4 having positive power with its image side (lens surface S10) facing convex toward the image side; a fifth lens L5; and a sixth lens L6. The fifth lens L5 and the sixth lens L6 are cemented lenses, and the second lens L2 has its object side (lens surface S3) facing concave toward the object side. This makes it possible to provide a compact imaging lens system with improved imaging performance and high resolution.

[0040] The bandpass filter 14 (BPF) of the camera module 10 is a filter that allows only light rays of a predetermined wavelength to pass through. For example, the bandpass filter 14 transmits light rays in the wavelength range of 435 nm to 680 nm. The bandpass filter 14 has a BPF surface S15 and a BPF surface S16.

[0041] The cover glass 13 (CG) of the camera module 10 is a glass plate for protecting the image sensor 12. The cover glass 13 has a CG surface S17 and a CG surface S18. The image sensor 12 (IMG) is an element that captures light rays (images) in the wavelength range of 435 nm to 680 nm and has an imaging surface S19.

[0042] Thus, the camera module 10 comprises an imaging lens system 11, an optical aperture 1, a bandpass filter 14, a cover glass 13, and an image sensor 12, with each edge fixed to the housing (barrel, etc.) of the camera module 10 or the imaging lens system 11 by a flange or the like. The optical aperture 1 is installed integrally with the imaging lens system 11, but it is not an essential component of the imaging lens system 11, and the optical aperture 1 is optional.

[0043] Furthermore, the optical aperture 1 is installed between the third lens L3 and the fourth lens L4, but it may also be installed between the second lens L2 and the third lens L3, or at any position between the first lens L1 and the sixth lens L6. By installing the optical aperture 1, the front element diameter of the first lens L1 can be further reduced in the imaging lens system 11. In addition, the imaging lens system 11 may have multiple optical apertures.

[0044] Furthermore, the camera module 10 includes a bandpass filter 14 between the sixth lens L6 and the cover glass 13. Additionally, the camera module 10 does not necessarily require the cover glass 13.

[0045] Table 1 shows the lens data for each lens surface of the imaging lens system 11 in Example 1.

[0046] [Table 1]

[0047] Table 1, the lens data table, shows the paraxial radius of curvature R, interplanar spacing D, refractive index Nd, and Abbe number vd for each surface. Note that interplanar spacing D(i) is the distance between surfaces S(i) and S(i+1) on the optical axis O. For example, it indicates that the central thickness on the optical axis O, which is the distance between the object-side lens surface S1 and the image-side lens surface S2, is 1.000 mm.

[0048] Furthermore, surfaces marked with an asterisk (*) (for example, lens surface S3 of the second lens L2) indicate aspherical lens surfaces. That is, the second lens L2, the third lens L3, the fifth lens L5, and the sixth lens L6 are aspherical lenses. Moreover, such aspherical lens surfaces can effectively correct spherical aberration and coma aberration. The aspherical shapes used for the aspherical lens surfaces in Table 1 are represented by Equation 1.

[0049]

number

[0050] Here, Z is the sag amount. c is the reciprocal of the paraxial radius of curvature R, k is the conicity coefficient, and r is the height from the optical axis. A4, A6, A8, A10, A12, A14, and A16 represent the 4th, 6th, 8th, 10th, 12th, 14th, and 16th order aspherical coefficients, respectively.

[0051] Table 2 shows the aspheric coefficients and other parameters used to define the aspherical shape of the lens surface designated as aspherical in Table 1 in the imaging lens system 11 of Example 1.

[0052] [Table 2]

[0053] In Table 2, for example, "1.21519E-02" is "1.21519 × 10^ -2 It means "...".

[0054] Table 3 shows the characteristic values ​​for the imaging lens system 11 of Example 1, as shown in Tables 1 and 2.

[0055] [Table 3]

[0056] In the imaging lens system 11, Fno is the F-number (F-value). An Fno of 2.0 ensures sufficient light and allows the imaging lens to be made brighter. Fno is generally smaller than Fno 2.8, which is considered a dark optical system. The imaging lens system 11 corrects various aberrations such as spherical aberration and coma aberration that occur when the effective aperture (e.g., entrance pupil diameter, exit pupil diameter) is increased and a bright optical system (e.g., F-value 2.0) is achieved.

[0057] ω represents the half-angle of view, and the full-angle view is 2ω. For example, in Example 1, the half-angle of view ω is approximately 90°, or 89°, and the horizontal angle of view (full-angle) is 178°, making it an ultra-wide-angle lens that supports a wide field of view of 100° or more. The range of the horizontal angle of view is preferably 160° to 220°. This lens may also be a fisheye lens with a horizontal angle of view of 180° or more.

[0058] f represents the focal length of the entire lens system from the first lens L1 to the sixth lens L6. f1 represents the focal length of the first lens L1. f2 represents the focal length of the second lens L2, f3 represents the focal length of the third lens L3, f4 represents the focal length of the fourth lens L4, f5 represents the focal length of the fifth lens L5, and f6 represents the focal length of the sixth lens L6.

[0059] TTL represents the total optical length along the optical axis O from the object-side lens surface S1 of the first lens L1 to the imaging surface S19 of the image sensor 12. Thus, the imaging lens system 11 is a compact lens system with an optical length of 20,000 mm or less. ICR is the image circle radius, and represents the radius of the circle in which the object is projected as a circle on the imaging surface S19 of the image sensor 12. Thus, as the image circle radius of the imaging lens system 11 increases, the number of pixels in the image sensor 12 increases, and a radius of 3.0 mm or more indicates a lens system with high imaging performance. In other words, an "ICR / TTL" of 0.15 or more indicates a compact lens system with high imaging performance.

[0060] "min sagL2R1" indicates the minimum sag amount of the object-side lens surface S3 of the second lens L2. "max sagL6R2" indicates the maximum sag amount of the image-side lens surface S14 of the sixth lens L6, and "min sagL6R2" indicates the minimum sag amount of the image-side lens surface S14 of the sixth lens L6.

[0061] Figure 2A shows the spherical aberration of the imaging lens system 11 of Example 1. The horizontal axis in Figure 2A represents the distance in the direction of the optical axis O. The vertical axis represents the pupil coordinates relative to the entrance pupil diameter. In addition, the solid line in Figure 2A represents the wavelength of light ray at 0.550 μm, the dashed line represents the wavelength of light ray at 0.470 μm, and the dotted line represents the wavelength at 0.630 μm. Thus, the imaging lens system 11 of Example 1 has little distance deviation in the direction of the optical axis O, and the spherical aberration is corrected to an appropriate range.

[0062] Figure 2B shows the field curvature of the imaging lens system 11 of Example 1. In Figure 2B, the horizontal axis represents the distance in the direction of the optical axis O, and the vertical axis represents the image height (angle of view). In Figure 2B, the dark solid line represents the field curvature in the tangential plane at a wavelength of 0.5500 μm, and the dark dotted line represents the field curvature in the sagittal plane at a wavelength of 0.5500 μm. The light solid line represents the field curvature in the tangential plane at a wavelength of 0.4700 μm, and the light dotted line represents the field curvature in the sagittal plane at a wavelength of 0.4700 μm. The pale solid line represents the field curvature in the tangential plane at a wavelength of 0.6300 μm, and the pale dotted line represents the field curvature in the sagittal plane at a wavelength of 0.6300 μm. Thus, in the imaging lens system 11 of Example 1, the distance deviation in the direction of the optical axis O of each field curvature is small, and the field curvature is corrected to an appropriate range.

[0063] Figure 2C shows the distortion aberration of the imaging lens system 11 of Example 1. In Figure 2C, the horizontal axis represents the ratio in the optical axis O direction, and the vertical axis represents the field of view (image height). In Figure 2C, the dark solid line represents a wavelength of light of 0.5500 μm, the light solid line represents a wavelength of light of 4700 μm, and the pale solid line represents a wavelength of 0.6300 μm. Thus, in the imaging lens system 11 of Example 1, the ratio in the optical axis O direction is small, and the distortion aberration is corrected to an appropriate range.

[0064] [Example 2] Figure 3 is a cross-sectional view showing the configuration of the imaging lens system 11 of the camera module 10 of Embodiment 2. The sixth lens L6 has an aspherical lens surface S13 with positive curvature that is convex towards the object side, and an aspherical lens surface S14 with positive curvature that is concave towards the paraxial side on the image side. The sixth lens L6 is a positive lens with negative power and is a meniscus-shaped plastic lens.

[0065] The configuration of the imaging lens system 11 in Example 2 is the same as in Example 1, except for the sixth lens L6, so its explanation is omitted. Similarly, the configuration of the camera module 10 in Example 2 is the same as in Example 1, so its explanation is omitted. This Example 2 differs from Example 1 in the following ways regarding lens data, etc.

[0066] Table 4 shows the lens data for each lens surface of the imaging lens system 11 in Example 2. The lens data in Table 4 shows data for the same items as in Table 1.

[0067] [Table 4]

[0068] Table 5 shows the aspheric coefficients and other parameters used to define the aspherical shape of the aspherical lens surface in the imaging lens system 11 of Example 2. Table 5 shows the same values ​​for the same items as in Table 2.

[0069] [Table 5]

[0070] Table 6 shows the characteristic values ​​for the imaging lens system 11 of Example 2, as shown in Tables 4 and 5, etc., for the same items as in Table 3.

[0071] [Table 6]

[0072] Figure 4A shows the spherical aberration of the imaging lens system 11 of Example 2, Figure 4B shows the field curvature of the imaging lens system 11 of Example 2, and Figure 4C shows the distortion aberration of the imaging lens system 11 of Example 2. Since Figures 4A to 4C show graphs for the same items as Figures 2A to 2C, the explanation for each aberration diagram is the same and will be omitted.

[0073] [Example 3] Figure 5 is a cross-sectional view showing the configuration of the imaging lens system 11 of the camera module 10 of Embodiment 3. The fourth lens L4 has a spherical lens surface S9 with negative curvature and a concave shape on the paraxial side toward the object, and a spherical lens surface S10 with negative curvature and a convex shape toward the image side. The fourth lens L4 is a positive lens with positive power and is a glass lens.

[0074] The fifth lens L5 has an aspherical lens surface S11 with positive curvature that is convex towards the object side, and an aspherical lens surface S12 with negative curvature that is convex towards the image side. The fifth lens L5 is a positive lens with positive power and is made of plastic.

[0075] The sixth lens L6 has an aspherical lens surface S13 with negative curvature and a concave shape on the object side, and an aspherical lens surface S14 with negative curvature and a paraxially convex shape on the image side. The sixth lens L6 is a negative lens with negative power and is a meniscus-shaped plastic lens. The fifth lens L5 is joined to the sixth lens L6, and the fifth lens L5 and the sixth lens L6 form a cemented lens. This cemented lens has negative power.

[0076] The configuration of the imaging lens system 11 in Example 3 is the same as in Example 1, except for the 4th lens L4 to the 6th lens L6, so its explanation is omitted. Also, the configuration of the camera module 10 in Example 3 is the same as in Example 1, so its explanation is omitted. This Example 3 differs from Example 1 in the following ways regarding lens data, etc.

[0077] Table 7 shows the lens data for each lens surface of the imaging lens system 11 in Example 3. The lens data in Table 7 shows data for the same items as in Table 1.

[0078] [Table 7]

[0079] Table 8 shows the aspheric coefficients and other parameters used to define the aspherical shape of the aspherical lens surface in the imaging lens system 11 of Example 3. Table 8 shows the same values ​​for the same items as in Table 2.

[0080] [Table 8]

[0081] Table 9 shows the characteristic values ​​for the imaging lens system 11 of Example 3, as shown in Tables 7 and 8, etc., for the same items as in Table 3.

[0082] [Table 9]

[0083] Figure 6A shows the spherical aberration of the imaging lens system 11 of Example 3, Figure 6B shows the field curvature of the imaging lens system 11 of Example 3, and Figure 6C shows the distortion aberration of the imaging lens system 11 of Example 3. Since Figures 6A to 6C show graphs for the same items as Figures 2A to 2C, the explanation for each aberration diagram is the same and will be omitted.

[0084] [Summary of conditional expressions] Table 10 summarizes the main characteristic values ​​and calculated related values ​​of the imaging lens system 11 in Examples 1 to 3.

[0085] [Table 10]

[0086] The imaging lens system 11 satisfies the following condition (1) when the radius of curvature of the lens surface S3, which is the object side surface of the second lens L2, is L2R1, and the focal length of the entire optical system is f. -1.7 <L2R1 / f<-1.5 ···(1) By satisfying condition (1), it is possible to provide a compact imaging lens system with improved imaging performance and even higher resolution. Furthermore, it is preferable that "L2R1 / f" satisfies -1.68 ≤ L2R1 / f ≤ -1.57.

[0087] The imaging lens system 11 satisfies the following condition (2) when the minimum sag amount of the lens surface S3, which is the object side surface of the second lens L2, is "min sagL2R1", and the focal length of the entire optical system is f. -0.35 <min sagL2R1 / f<-0.18 ···(2) By satisfying condition (2), the image circle radius can be increased relative to the total length of the optical system, thereby improving imaging performance. This makes it possible to provide a compact imaging lens system with improved imaging performance and even higher resolution. Furthermore, it is preferable that "min sagL2R1 / f" satisfies -0.32 ≤ min sagL2R1 / f ≤ -0.20.

[0088] The imaging lens system 11 satisfies the following condition (3) when the maximum sag amount of the lens surface S14, which is the image side of the sixth lens L6, is "max sagL6R2", and the total optical length along the optical axis O from the object-side lens surface S1 of the first lens L1 to the imaging surface S19 of the image sensor 12 is TTL. |max sagL6R2 / TTL|<0.004 ···(3) By satisfying condition (3), it is possible to provide an imaging lens system that is compact, has improved imaging performance, and possesses even higher resolution. Furthermore, it is desirable that 0.001 < |max sagL6R2 / TTL|. It is even better if |max sagL6R2 / TTL| satisfies 0.0013 ≤ |max sagL6R2 / TTL| ≤ 0.0032.

[0089] The imaging lens system 11 satisfies the following condition (4) when the focal length of the third lens L3 is f3 and the focal length of the fourth lens L4 is f4. 1.1 <f3 / f4<1.3 ···(4) By satisfying condition (4), it is possible to provide a compact imaging lens system with improved imaging performance and even higher resolution. Furthermore, it is preferable that "f3 / f4" satisfies 1.12 ≤ f3 / f4 ≤ 1.23.

[0090] The imaging lens system 11 satisfies the following condition (5) when the focal length of the second lens L2 is f2 and the focal length of the entire optical system is f. -3.0 <f2 / f<-2.0 ···(5) By satisfying condition (5), it is possible to provide a compact imaging lens system with improved imaging performance and even higher resolution. Furthermore, it is preferable that f2 satisfies -2.7 ≤ f2 / f ≤ -2.4.

[0091] The imaging lens system 11 satisfies the following condition (6) when the focal length of the third lens L3 is f3 and the focal length of the entire optical system is f. 2.0 <f3 / f<3.0 ···(6) By satisfying condition (6), it is possible to provide a compact imaging lens system with improved imaging performance and even higher resolution. Furthermore, it is preferable that "f3 / f" satisfies 2.84 ≤ f3 / f ≤ 2.90.

[0092] The imaging lens system 11 satisfies the following condition (8) when the horizontal angle of view (full angle) is 2ω. 160<2ω ···(8) By satisfying condition (8), it is possible to provide a compact imaging lens system with improved imaging performance and even higher resolution.

[0093] [Differentiation] The present invention is not limited to the embodiments described above, and includes various other modifications. For example, the embodiments described above are described in detail to make the present invention easier to understand, and are not necessarily limited to those having all the configurations described.

[0094] Furthermore, it is possible to replace parts of the configuration of one embodiment with parts of the configuration of another embodiment, and it is also possible to add parts of the configuration of another embodiment to the configuration of one embodiment. In addition, it is possible to add, delete, or replace parts of the configuration of each embodiment with parts of other configurations. [Embodiment 2] Figure 7 shows the configuration of an imaging device 50 equipped with the imaging lens system 11 of Embodiment 1. As shown in the figure, the imaging device 50 according to the embodiment includes a camera module 10 that houses the imaging lens system 11 and an image sensor 12 etc. in a housing (not shown), a control unit 52, and a storage unit 54.

[0095] 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. This control unit 52 may be composed of, for example, a processor unit (PU), RAM, ROM, etc. The control unit 52 may also include one or more processors.

[0096] The processor may include a general-purpose processor that loads a specific program and executes 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 integrated circuit (ASIC) is also called an application-specific integrated circuit (ASIC). The processor may also include a programmable logic device (Programmable Logic Device). A programmable logic device (PLD) 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 cooperate.

[0097] The storage unit 54 stores various information or parameters related to the operation of the imaging device 50. The storage unit 54 may be composed of, for example, a semiconductor memory. 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 information or parameters for the control unit 52 to perform detection processing and control based on the captured images. The storage unit 54 may be included in the control unit 52.

[0098] As mentioned above, the camera module 10 captures an image of a subject (object) formed via the imaging lens system 11 using the image sensor 12, and outputs the captured image. The image captured by the camera module 10 is also called the captured image.

[0099] The image sensor 12 may be composed of, for example, a CMOS (Complementary Metal Oxide Semiconductor) image sensor or a CCD (Charge Coupled Device). The image sensor 12, positioned at the focal point of the imaging lens system 11, has an imaging surface in which multiple pixels are arranged. Each pixel outputs a signal that is specified by current or voltage according to the amount of incident light. The signal output by each pixel is also called imaging data.

[0100] The imaging data may be read out by the camera module 10 for all pixels and taken into the control unit 52 as an image. The image obtained by reading out all pixels is also called the maximum image. The imaging data may be read out by the camera module 10 for some pixels and taken into the image. In other words, the imaging data may be read out from pixels within a predetermined acquisition range. The imaging data read out from pixels within a predetermined acquisition range may be taken into the image. The predetermined acquisition range may be set by the control unit 52. The camera module 10 may obtain the predetermined acquisition range from the control unit 52. The image sensor 12 may capture an image within a predetermined acquisition range from the subject image formed via the imaging lens system 11. Alternatively, the imaging device 50 (imaging camera) may be an imaging system in which the camera module 10 is a separate unit connected by cables or the like. [Embodiment 3] Figure 8 is a schematic diagram of a vehicle 40 equipped with an in-vehicle system that includes an imaging device 50 comprising an imaging lens system according to Embodiment 1 or Embodiment 2 and an image sensor that converts the light focused through the lens into an electrical signal.

[0101] As shown in Figure 8, the vehicle 40, which is a motor vehicle that travels day and night, is equipped with tires, steering, etc., for driving. The mobile vehicle 40 is equipped with an imaging device 50 that can obtain bright, high-resolution images corresponding to a wide field of view. The vehicle 40 is also equipped with an information processing device 42, a display device 43, etc.

[0102] Figure 8 shows several example arrangements illustrating the mounting positions of the imaging devices 50 in the vehicle 40. For example, the first imaging device 50a, which is one of the imaging devices 50, may be placed on or near the front bumper as a camera to monitor the area in front of the vehicle 40 while it is in motion. The second imaging device 50b, which is another imaging device 50 that monitors the area in front, may be placed near the rearview mirror inside the vehicle 40. The third imaging device 50c may be placed on the dashboard or inside the instrument panel, etc., as a camera to monitor the driver's driving conditions. The fourth imaging device 50d may be installed at the rear of the vehicle 40 for use as a rear monitor.

[0103] The first imaging device 50a and the second imaging device 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 can be 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, and is an imaging device that can provide a wide field of view with few blind spots. In this way, the imaging lens system 11 within the imaging device 50 can be installed in various positions on the vehicle 40.

[0104] Figure 9 is a diagram showing the configuration of a vehicle 40 on which an in-vehicle system 41 is mounted, which includes an imaging device 50 comprising an imaging lens system 11 according to Embodiment 1 or Embodiment 2 and an image sensor 12 that converts the light focused through thereon into an electrical signal.

[0105] As shown in Figure 9, the imaging device 50 mounted on the vehicle 40 as an automobile can also be called an on-board camera and can be installed in various locations on the vehicle 40. Furthermore, the on-board system 41 equipped with the imaging device 50 etc. mounted on the vehicle 40 as an automobile is also a mobile system equipped with the imaging device 50 etc. mounted on a mobile body. In other words, the mobile body is not limited to the vehicle 40 as an automobile, but includes, for example, a moving bicycle, motorcycle, wheelchair, train, drone, helicopter, airplane, ship, etc.

[0106] As shown in Figure 9, the image signal of the captured image captured by the imaging device 50 is output to the information processing device 42, display device 43, etc. of the vehicle 40 via a cable or bus, etc. Furthermore, the image signal of the captured image may be output to the information processing device, display device, etc. of the control center via wireless or network, etc. The in-vehicle system 41 comprises at least the information processing device 42 and the imaging device 50. The in-vehicle system 41 may also comprise the information processing device 42, the imaging device 50, and the display device 43, etc.

[0107] The information processing device 42 of the vehicle 40 acquires the captured image output from the camera module 10 of the imaging device 50 and processes the image signal of the captured image. The information processing device 42 may also process the captured images acquired by the first imaging device 50a and the second imaging device 50b, which are imaging devices 50 as shown in Figure 8, by combining them. The information processing device 42 may be composed of, for example, a processor unit (PU), RAM, ROM, etc.

[0108] The information processing device 42 recognizes various objects in the captured image, such as people (including the driver of the vehicle 40 captured by the in-camera), other vehicles, other moving objects, animals, roads, and road signs, and generates recognition information such as images of the objects, their type, location, and speed of movement.

[0109] The captured images may be images of the vehicle 40 in the direction of movement, or one or more images that meet predetermined conditions, for example, one image when the vehicle 40 is traveling at a predetermined speed or higher, and multiple images when it is traveling at a speed lower than that.

[0110] The information processing device 42 includes devices that assist the driver in driving. For example, the information processing device 42 includes, but is not limited to, a navigation device, a collision damage mitigation braking device, a distance control device, and a lane departure warning device.

[0111] The display device 43 displays images and other recognition information processed and output by the information processing device 42 as an output device, but it may also notify audio, which is recognition information corresponding to the images and other recognition information, using an audio output device as an output device.

[0112] Furthermore, the display device 43 may employ, but is not limited to, a liquid crystal display (LCD), an organic electro-luminescence (EL) display, or an inorganic EL display. The display device 43 can also directly receive image signals, such as captured images output from an imaging device 50 that captures images from a position difficult for the driver to see, such as a rear camera, for example, a fourth imaging device 50d, and display the captured images to the driver or other occupants. The display device 43 may also be an output device equipped with an audio output device that outputs sound, etc., based on the image signal.

[0113] It should be noted that the present invention is not limited to the embodiments described above, and can be modified as appropriate without departing from the spirit of the invention. For example, the applications of the imaging lens system 11 of the present invention are not limited to in-vehicle cameras, but can also be used in other applications such as fixed surveillance cameras, digital cameras, and cameras mounted on small electronic devices such as portable mobile phones.

[0114] Furthermore, the present invention includes various embodiments other than those described above. For example, the above-described embodiments are explained in detail to make the present invention easier to understand, and are not necessarily limited to those having all the configurations described.

[0115] Furthermore, the present invention allows for the replacement of parts of the configuration of one embodiment with the configuration of another embodiment, and also allows for the addition of configurations from other embodiments to the configuration of one embodiment. In addition, the present invention allows for the addition, deletion, and replacement of parts of the configuration of each embodiment with other configurations. [Explanation of symbols]

[0116] 1: Optical aperture (STOP), 10: Camera module, 11: Imaging lens system, 12: Image sensor (IMG), 13: Cover glass (CG), 14: Bandpass filter (BPF), 40: Vehicles, 41: In-vehicle systems, 42: Information processing equipment, 43:Display device, 50, 50a, 50b, 50c, 50d: Imaging devices (imaging cameras, in-vehicle cameras) 52: Control unit, 54: Memory section, L1: First lens, L2: Second lens, L3: Third lens, L4: Fourth lens, L5: Fifth lens, L6: 6th lens, L7: 7th lens, S1~S6, S9~S14: Lens surface, S7, S8: Optical aperture surface, S15, S16: BPF surface, S17, S18: CG surface, S19: Imaging plane.

Claims

1. Starting from the object side and moving towards the image side, A first lens having negative power, in which the object side faces convex toward the object and the image side faces concave toward the image, A second lens having negative power with the image side facing the image side as a concave surface, A third lens having positive power with its image side facing the image side as a convex surface, Aperture and, A fourth lens having positive power with its image side facing the image side as a convex surface, The fifth lens, Equipped with a sixth lens, The fifth lens and the sixth lens are cemented lenses, The second lens is an imaging lens system in which the side surface of the object faces the object.

2. In the imaging lens system described in claim 1, An imaging lens system that satisfies the following condition (1), where L2R1 is the radius of curvature of the object side of the second lens and f is the focal length of the entire optical system. -1.7<L2R1 / f<-1.5...(1)

3. In the imaging lens system described in claim 1, An imaging lens system that satisfies the following condition (2), where "min sagL2R1" is the minimum sag amount on the side surface of the second lens and f is the focal length of the entire optical system. -0.35<min sagL2R1 / f<-0.18...(2)

4. In the imaging lens system described in claim 1, An imaging lens system that satisfies the following condition (3), where "max sagL6R2" is the maximum sag amount on the image side of the sixth lens, and TTL is the total optical length on the optical axis from the object side of the first lens to the imaging plane of the image sensor. |max sagL6R2 / TTL|<0.004...(3)

5. In the imaging lens system described in claim 1, An imaging lens system that satisfies the following condition (4) when the focal length of the third lens is f3 and the focal length of the fourth lens is f4. 1.1<f3 / f4<1.3...(4)

6. In the imaging lens system described in claim 1, An imaging lens system that satisfies the following condition (5), where the focal length of the second lens is f2 and the focal length of the entire optical system is f. -3.0<f2 / f<-2.0...(5)

7. In the imaging lens system described in claim 1, An imaging lens system that satisfies the following condition (6), where the focal length of the third lens is f3 and the focal length of the entire optical system is f. 2.0<f3 / f<3.0...(6)

8. In the imaging lens system described in claim 1, An imaging lens system that satisfies the following condition (7) when the horizontal angle of view is 2ω. 160<2ω...(7)

9. The imaging lens system according to any one of claims 1 to 8, A camera module comprising an image sensor that converts light collected through the aforementioned imaging lens system into an electrical signal.

10. An imaging device comprising: a camera module according to claim 9; a control unit for controlling the camera module; and a storage unit for storing information for the control unit to perform control.

11. An in-vehicle system comprising a camera module as described in claim 9, and an information processing device that recognizes an object in an image captured by the camera module and generates recognition information.

12. A mobile body comprising: a camera module according to claim 11; an information processing device that recognizes an object in an image captured by the camera module and generates recognition information; and an output device that outputs the recognition information.

Images