Image capturing lens system, camera module, in-vehicle system, and mobile vehicle

Abstract

To provide an image capturing lens system which offers sufficient brightness and a sufficient angle of view for monitoring the inside of a cabin during nighttime, and to provide a camera module, in-vehicle system, and mobile vehicle.SOLUTION: An image capturing lens system 11 disclosed herein consists of six lenses, namely a front group Gf, an aperture stop STOP, and a rear group Gr. Specifically, the image capturing lens system consists of a first lens L1 with negative power having a concave surface facing the image side, a second lens L2 having a concave surface facing the object side, a third lens L3 with positive power, a fourth lens L4 with power, a fifth lens L5 with power and a sixth lens L6 with power, and satisfies the following conditional expression (1): -3.0<f1 / f<-1.0 ...(1), where f1 represents a focal length of the first lens L1, and f represents a focal length of the entire optical system.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Patent Document 1 describes an on-vehicle imaging lens system that has a field angle suitable for front sensing, while Patent Document 2 describes a lens system for a surveillance camera that has a large aperture ratio that allows for good surveillance even at night or in dimly lit places. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6796515 [Patent Document 2] Patent No. 5854966 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the imaging lens system described in Patent Document 1 has an F-number of 2.0, which is insufficient in brightness for monitoring the interior of a vehicle at night or for sensing at night or in bad weather.Furthermore, the lens system described in Patent Document 2 has a total angle of view of 20°, which is too narrow for monitoring the driver, passengers in the front passenger seat, and passengers in the back seat of a vehicle.

[0005] The present invention has been made in consideration of the above problems, and aims to provide an imaging lens system, a camera module, an in-vehicle system, and a moving body that have sufficient brightness and angle of view for monitoring the interior of a vehicle at night. [Means for solving the problem]

[0006] An imaging lens system of one embodiment is composed of substantially six lenses, including, in order from the object side to the image side, a front group, an aperture stop, and a rear group, and the six lenses include a first lens having a negative power and a concave surface on the image side facing the image side, a second lens having a concave surface on the object side facing the object side, a third lens having positive power, a fourth lens having power, a fifth lens having power, and a sixth lens having power. When the focal length of the first lens is defined as f1 and the focal length of the entire optical system is defined as f, the following conditional expression (1) is satisfied. -3.0 <f1 / f<-1.0 ···(1) [Effects of the Invention]

[0007] According to the present invention, it is possible to provide an imaging lens system, a camera module, an in-vehicle system, and a moving body that have sufficient brightness and angle of view for monitoring the interior of a vehicle at night. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view showing the configuration of a camera module and an imaging lens system according to a first embodiment. [Figure 2] 3A to 3C are diagrams showing spherical aberration (longitudinal aberration), curvature of field, and distortion in the imaging lens system of Example 1. [Figure 3] FIG. 10 is a cross-sectional view showing the configuration of a camera module and an imaging lens system according to a second embodiment. [Figure 4] 10A to 10C are diagrams showing spherical aberration (longitudinal aberration), curvature of field, and distortion in the imaging lens system of Example 2. [Figure 5] FIG. 10 is a cross-sectional view showing the configuration of a camera module and an imaging lens system according to a third embodiment. [Figure 6] 10A to 10C are diagrams showing spherical aberration (longitudinal aberration), curvature of field, and distortion in the imaging lens system of Example 3. [Figure 7] FIG. 10 is a cross-sectional view showing the configuration of a camera module and an imaging lens system according to a fourth embodiment. [Figure 8] 10A to 10C are diagrams showing spherical aberration (longitudinal aberration), curvature of field, and distortion in the imaging lens system of Example 4. [Figure 9] FIG. 10 is a cross-sectional view showing the configuration of a camera module and an imaging lens system according to a fifth embodiment. [Figure 10] 10A to 10C are diagrams showing spherical aberration (longitudinal aberration), curvature of field, and distortion in the imaging lens system of Example 5. [Figure 11] 1 is a schematic diagram of a vehicle equipped with an in-vehicle system including a camera module according to an embodiment of the present invention. [Figure 12] 12 is a block diagram showing the configuration of an imaging device that constitutes the in-vehicle system of FIG. 11. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings. This embodiment can realize a highly reliable system, particularly in a sensing system, and contributes to the development of resilient infrastructure. The target is "9.1 Develop quality, reliable, sustainable and resilient infrastructure, including regional and transborder infrastructure, to support economic development and human well-being, with a focus on affordable and equitable access for all," which is one of the Sustainable Development Goals (SDGs) advocated by the United Nations. (Embodiment 1: Imaging lens system) The imaging lens system according to the first embodiment is composed of substantially six lenses, namely, in order from the object side to the image side, a front group, an aperture stop, and a rear group, which include a first lens having negative power and whose image-side surface is concave toward the image side, a second lens having a concave object-side surface facing the object side, a third lens having positive power, a fourth lens having power, a fifth lens having power, and a sixth lens having power. When the focal length of the first lens is defined as f1 and the focal length of the entire optical system is defined as f, the following conditional expression (1) is satisfied. -3.0 <f1 / f<-1.0 ···(1)

[0010] This makes it possible to provide an imaging lens system that has sufficient brightness and angle of view for monitoring the interior of a vehicle at night. Specifically, when the angle of view of an imaging lens system is widened, the diameter of light incident on the imaging lens system becomes thicker, increasing the effective beam radius of the lens, and making aberration correction particularly necessary in the peripheral area within the effective beam radius of the lens. Here, the "effective beam radius" refers to the distance from the optical axis to the maximum peripheral ray passing through the lens surface. Similarly, when the F-number (F number, Fno) is small, the effective beam radius of the lens increases, and making aberration correction particularly necessary in the peripheral area within the effective beam radius of the lens. By satisfying the above conditional expression (1), various aberrations such as field curvature and distortion can be corrected, resulting in an imaging lens system with high resolution, sufficient brightness, and a field angle. More specifically, when the value of f1 / f is -1.0 or greater, the power of the first lens is too strong, resulting in overcorrection of various aberrations such as field curvature and distortion in the peripheral area within the effective beam radius of the first lens. On the other hand, if the value of f1 / f is −3.0 or less, the power of the first lens is too weak, and various aberrations such as field curvature and distortion in the peripheral area within the effective ray radius of the first lens cannot be sufficiently corrected. Therefore, if the imaging lens system satisfies conditional expression (1), it is possible to provide an imaging lens system that has sufficient brightness and angle of view for monitoring the interior of a vehicle at night.

[0011] The third lens is preferably a glass lens, which has a relatively small linear expansion coefficient. By using a glass lens with a relatively small linear expansion coefficient for the third lens, the positive power of the third lens can be made stronger than that of the other lenses, and the third lens can compensate for the amount of focus shift caused by changes in environmental temperature.

[0012] In addition, in the imaging lens system, it is preferable that the third lens has the strongest positive power, which allows the third lens to compensate for the focus shift of the other lenses with negative power caused by changes in environmental temperature.

[0013] Furthermore, when the focal length of the third lens in the imaging lens system is defined as f3, it is preferable that the imaging lens system satisfies the following conditional expression (2): 1.2 <f3 / f<2.0 ···(2) When the imaging lens system satisfies the above conditional expression (2), the third lens can appropriately correct spherical aberration and lateral aberration, thereby realizing an imaging lens system with high resolution, sufficient brightness, and a sufficient angle of view. Specifically, when the value of f3 / f is 1.2 or less, the focal length of the third lens is too short relative to the focal length of the entire optical system. In other words, the positive power of the third lens is too strong, resulting in excessive correction of spherical aberration and lateral aberration. On the other hand, when the value of f3 / f is 2.0 or more, the focal length of the third lens is too long relative to the focal length of the entire optical system. In other words, the positive power of the third lens is too weak, resulting in insufficient correction of spherical aberration and lateral aberration.

[0014] Furthermore, when the combined focal length of the first lens and the second lens is defined as f12, it is preferable that the imaging lens system satisfies the following conditional expression (3): -2.0 <f12 / f<-1.3 ···(3) When the imaging lens system satisfies the above conditional expression (3), distortion and lateral aberration can be suitably corrected in the first and second lenses, and an imaging lens system with high resolution, sufficient brightness, and a sufficient angle of view can be realized. If the value of f12 / f is -1.3 or greater, the combined power of the first and second lenses is too strong, resulting in excessive correction of distortion and lateral aberration. On the other hand, if the value of f12 / f is -2.0 or less, the combined power of the first and second lenses is too weak, resulting in insufficient correction of distortion and lateral aberration.

[0015] The second, fourth, fifth, and sixth lenses are preferably plastic lenses. By using plastic lenses for the second, fourth, fifth, and sixth lenses, manufacturing costs can be reduced.

[0016] Furthermore, when the focal length of the second lens in the imaging lens system is defined as f2, it is preferable that the imaging lens system satisfies the following conditional expression (4): -30 <f2 / f<-5 ···(4) When the imaging lens system satisfies the above conditional expression (4), spherical aberration and lateral aberration are suitably corrected, and an imaging lens system having high resolution, sufficient brightness, and a wide angle of view can be realized. Specifically, when the value of f2 / f is -5 or greater, the focal length of the second lens is too short relative to the focal length of the entire optical system; in other words, the power of the second lens is too strong, resulting in excessive correction of spherical aberration and lateral aberration. On the other hand, when the value of f2 / f is -30 or less, the focal length of the second lens is too long relative to the focal length of the entire optical system; in other words, the power of the second lens is too weak, resulting in insufficient correction of spherical aberration and lateral aberration.

[0017] Furthermore, when the focal length of the fifth lens is defined as f5, it is preferable that the imaging lens system satisfies the following conditional expression (5): 1.5 <f5 / f<7 ···(5) When the imaging lens system satisfies the above conditional expression (5), lateral aberration and curvature of field can be suitably corrected, and an imaging lens system with high resolution, sufficient brightness, and a sufficient angle of view can be realized. Specifically, when the value of f5 / f is 1.5 or less, the focal length of the fifth lens is too short relative to the focal length of the entire optical system. In other words, the power of the fifth lens is too strong, resulting in excessive correction of lateral aberration and curvature of field. On the other hand, when the value of f5 / f is 7 or more, the focal length of the fifth lens is too long relative to the focal length of the entire optical system. In other words, the power of the fifth lens is too weak, resulting in insufficient correction of lateral aberration and curvature of field.

[0018] Furthermore, when the focal length of the sixth lens is defined as f6, it is preferable that the imaging lens system satisfies the following conditional expression (6): 3 <f6 / f<50 ···(6) By making the imaging lens system satisfy the above conditional expression (6), lateral aberration and curvature of field can be suitably corrected, and an imaging lens system with high resolution, sufficient brightness, and a sufficient angle of view can be realized. Specifically, when the value of f6 / f is 3 or less, the focal length of the sixth lens is too short relative to the focal length of the entire optical system. In other words, the power of the sixth lens is too strong, resulting in excessive correction of lateral aberration and curvature of field. On the other hand, when the value of f6 / f is 50 or more, the focal length of the sixth lens is too long relative to the focal length of the entire optical system. In other words, the power of the sixth lens is too weak, resulting in insufficient correction of curvature of field and distortion. The lower limit of f6 / f is more preferably 7.0. The upper limit of f6 / f is more preferably 20.

[0019] Furthermore, when the design wavelength of the imaging lens system is defined as WL, it is preferable that the imaging lens system satisfies the following conditional expression (7). 800nm <WL<1000nm ···(7) If the imaging lens system satisfies the above conditional expression (7), it will be able to detect infrared light, enabling sensing at night or in bad weather.

[0020] Furthermore, when the half angle of view of the imaging lens system is defined as ω, it is preferable that the imaging lens system satisfies the following conditional expression (8): ω>60° (8) When the imaging lens system satisfies the above conditional expression (8), it is possible to realize an imaging lens system that has a wide angle of view, high resolution, sufficient brightness, and a sufficient angle of view.

[0021] (Embodiment 2: Camera Module) The camera module according to the second embodiment includes the imaging lens system described above and an imaging element disposed at the focal position of the imaging lens system and converting light collected through the imaging lens system into an electrical signal, thereby providing a camera module with sufficient brightness and angle of view for monitoring the interior of a vehicle at night.

[0022] Next, examples corresponding to the imaging lens system according to the first embodiment and the camera module according to the second embodiment will be described with reference to the drawings. Example 1 1 is a cross-sectional view showing the configuration of a camera module 10 of Example 1. Specifically, camera module 10 includes an imaging lens system 11 and an imaging element 12. Imaging lens system 11 and imaging element 12 are housed in a housing (not shown).

[0023] 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 imaging position (focal position) of the imaging lens system 11.

[0024] The imaging lens system 11 according to Example 1 comprises, in order from the object side to the image side, a front group Gf consisting of a first lens L1 and a second lens L2, an aperture stop (STOP), and a rear group Gr consisting of a third lens L3, a fourth lens L4, a fifth lens L5, and a sixth lens L6. The imaging plane of the imaging lens system 11 is indicated by IMG. The first lens L1 and the third lens L3 are glass lenses. The second lens L2, the fourth lens L4, the fifth lens L5, and the sixth lens L6 are plastic lenses. If necessary, an optical filter (such as an infrared transmission filter or a visible / infrared bandpass filter) may be disposed between the imaging lens system 11 and the imaging element 12. In this specification, an example in which an infrared transmission filter (FILTER) is disposed between the imaging lens system 11 and the imaging element 12 will be described.

[0025] The first lens L1 is a meniscus lens with 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.

[0026] The second lens L2 is a meniscus lens with negative power. The object-side surface S3 of the second lens L2 has an aspheric shape with a concave surface facing the object side. The image-side surface S4 of the second lens L2 has an aspheric shape with a convex surface facing the image side.

[0027] The aperture stop STOP is an aperture that determines the F-number (F-number, Fno) of the lens system. The aperture stop STOP is disposed between the second lens L2 and the third lens L3.

[0028] The third lens L3 has positive power. The object-side surface S7 of the third lens L3 has a spherical shape with a concave surface facing the object side. The image-side surface S8 of the third lens L3 has a spherical shape with a convex surface facing the image side.

[0029] The fourth lens L4 is a meniscus lens with negative power. The object-side surface S9 of the fourth lens L4 has an aspheric shape with a concave surface facing the object side. The image-side surface S10 of the fourth lens L4 has an aspheric shape with a convex surface facing the image side.

[0030] The fifth lens L5 is a lens having positive power. The object side surface S11 of the fifth lens L5 has an aspheric shape with a convex surface facing the object side. The image side surface S12 of the fifth lens L5 also has an aspheric shape with a convex surface facing the image side.

[0031] The sixth lens L6 is a lens having positive power. The object-side surface S13 of the sixth lens L6 has an aspheric shape with a concave surface facing the object side. The image-side surface S14 of the sixth lens L6 has an aspheric shape with a convex surface facing the image side.

[0032] The infrared transmission filter (FILTER) is a filter that transmits light in the near-infrared region and cuts light in the visible light region. When designing the imaging lens system 11, the infrared transmission filter is treated as an integral part of the imaging lens system 11. However, the infrared transmission filter is not an essential component of the imaging lens system 11. The infrared transmission filter is disposed on the image side of the sixth lens L6. Furthermore, a sensor cover glass may be placed between the infrared transmission filter and the imaging element 12 to prevent dust from adhering to the imaging element 12.

[0033] Table 1 shows lens data for each lens surface in the imaging lens system 11 of Example 1. Table 1 presents the lens data, including the radius of curvature (mm) of each surface, the surface spacing (mm) on the optical axis OA, the refractive index n850 for a design wavelength of 850 nm, the refractive index nd for the d-line, the Abbe number vd for the d-line, and the effective ray radius (mm). In Table 1, surfaces marked with an asterisk (*) are aspherical. In the imaging lens system 11 of Example 1, the F-number is 1.30 and the half angle of view (ω) is 73.6°.

[0034] [Table 1]

[0035] The aspheric shapes used on the lens surfaces are as follows: Z is the amount of sag, c is the inverse of the radius of curvature, k is the conic coefficient, and r is the ray height from the optical axis OA. The aspheric coefficients of the 4th, 6th, 8th, 10th, 12th, 14th, and 16th orders are α4, α6, α8, and α 10 , α 12 , α 14 , α 16 When this is the case, it is expressed by the following equation:

number

[0036] 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, "-6.515162E-01" corresponds to "-6.515162×10 -1 The same applies to the numerical expressions in the following tables.

[0037] [Table 2]

[0038] Next, aberrations will be described with reference to the drawings. Figure 2 shows diagrams of spherical aberration (longitudinal aberration), curvature of field, and distortion in the imaging lens system 11 of Example 1. In the longitudinal aberration diagram of Figure 2(A), the horizontal axis indicates the position where the light ray intersects with the optical axis OA, and the vertical axis indicates the height of the light ray passing through the entrance pupil. Figure 2(A) also shows the simulation results for a light ray of 850 nm. In the field curvature diagram of Figure 2(B), the horizontal axis represents the distance along the optical axis OA, and the vertical axis represents the image height (angle of view). In the field curvature diagram of Figure 2(B), Sag represents the image position for the sagittal ray bundle, and Tan represents the image position for the tangential ray bundle. Figure 2(B) also shows the simulation results for light of 850 nm. In the distortion diagram of Figure 2(C), the horizontal axis represents image distortion (%) and the vertical axis represents image height (angle of view). Figure 2(C) also shows the simulation results for light of 850 nm.

[0039] Example 2 FIG. 3 is a cross-sectional view showing a camera module 10 according to Example 2. In the imaging lens system 11 according to Example 2, the fourth lens L4 has positive power, the object-side surface S9 has an aspherical shape with a concave surface facing the object side, and the image-side surface S10 has an aspherical shape with a convex surface facing the image side. The fifth lens L5 has positive power, the object-side surface S11 has an aspherical shape with a concave surface facing the object side, and the image-side surface S12 has an aspherical shape with a convex surface facing the image side. The configuration of the imaging lens system 11 according to Example 2, other than the fourth lens L4 and the fifth lens L5, 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.

[0040] 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 of Example 2 has an F-number of 1.30 and a half angle of view (ω) of 73.3°.

[0041] [Table 3]

[0042] 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.

[0043] [Table 4]

[0044] 4 shows diagrams of spherical aberration (longitudinal aberration), field curvature, and distortion in the imaging lens system 11 of Example 2. The explanation of each aberration diagram shown in Fig. 4 is the same as that in Fig. 2, and therefore will not be repeated.

[0045] Example 3 5 is a cross-sectional view showing a camera module 10 according to Example 3. In the imaging lens system 11 according to Example 3, the sixth lens L6 has positive power, the object-side surface S13 has an aspherical shape with a convex surface facing the object side, and the image-side surface S14 has an aspherical shape with a concave surface facing the image side. The configuration of the imaging lens system 11 according to Example 3 other than the sixth lens L6 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 3 will be described.

[0046] Table 5 shows lens data for each lens surface of the imaging lens system 11 according to Example 3. In Table 5, instead of the refractive index n850 for light with a design wavelength of 850 nm, the refractive index n940 for light with a design wavelength of 940 nm is shown. The other 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 of Example 3 has an F-number of 1.30 and a half angle of view (ω) of 73.5°.

[0047] [Table 5]

[0048] 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.

[0049] [Table 6]

[0050] 6 shows diagrams of spherical aberration (longitudinal aberration), field curvature, and distortion in the imaging lens system 11 of Example 3. The explanation of each aberration diagram shown in FIG. 6 is the same as that in FIG. 2, and therefore will not be repeated.

[0051] 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 third lens L3 has positive power, the object-side surface S7 has a spherical shape with a convex surface facing the object side, and the image-side surface S8 has a spherical shape with a convex surface facing the image side. The fourth lens L4 has negative power, the object-side surface S9 has an aspherical shape with a concave surface facing the object side, and the image-side surface S10 has an aspherical shape with a concave surface facing the image side. The sixth lens L6 has positive power, the object-side surface S13 has an aspherical shape with a convex surface facing the object side, and the image-side surface S14 has an aspherical shape with a concave surface facing the image side. The imaging lens system 11 according to Example 4 has the same lens configuration as that of Example 1 except for the third lens L3, the fourth lens L4, and the sixth lens L6. Therefore, the characteristic data of the imaging lens system 11 according to Example 4 will be described below.

[0052] 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 1.30 and a half angle of view (ω) of 73.4°.

[0053] [Table 7]

[0054] 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.

[0055] [Table 8]

[0056] 8 shows diagrams of spherical aberration (longitudinal aberration), field curvature, and distortion in the imaging lens system 11 of Example 4. The explanation of each aberration diagram shown in Fig. 8 is the same as that in Fig. 2, and therefore will not be repeated.

[0057] Example 5 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 sixth lens L6 has positive power, the object-side surface S13 has an aspherical shape with a convex surface facing the object side, and the image-side surface S14 has an aspherical shape with a convex surface facing the image side. The configuration of the imaging lens system 11 according to Example 5 other than the sixth lens L6 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 5 will be described.

[0058] 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 of Example 5 has an F-number of 1.30 and a half angle of view (ω) of 73.3°.

[0059] [Table 9]

[0060] 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.

[0061] [Table 10]

[0062] 10 shows diagrams of spherical aberration (longitudinal aberration), field curvature, and distortion in the imaging lens system 11 of Example 5. The explanation of each aberration diagram shown in Fig. 10 is the same as that in Fig. 2, and therefore will not be repeated.

[0063] Table 11 shows the F-number of the imaging lens system 11, the total angle of view (2ω), the focal length f of the entire optical system of the imaging lens system 11, the focal length f 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 values of f1 / f, f3 / f, f12 / f, f2 / f, f5 / f, f6 / f, the WL value, and the half angle of view (ω). In Table 11, the focal lengths are in mm. The focal lengths shown in Table 11 were calculated using a design wavelength of 850 nm for Examples 1, 2, 4, and 5, and a design wavelength of 940 nm for Example 3.

[0064] [Table 11]

[0065] In Examples 1 to 5, the imaging lens system 11 satisfies conditional formula (1), so that it is possible to provide an imaging lens system 11 having sufficient brightness and angle of view for monitoring the interior of a vehicle at night. Specifically, in Examples 1 to 5, the F-number is 1.30, and the imaging lens system 11 has sufficient brightness. Also, in Examples 1 to 5, various aberrations can be suitably reduced as shown in FIGS. 2, 4, 6, 8, and 10. Therefore, in Examples 1 to 5, the imaging lens system 11 has high resolution. Also, in Examples 1 to 5, the half angle of view (ω) is 73.3° to 73.6°, and the imaging lens system 11 has a wide angle of view that is sufficient for sensing the interior of a vehicle, particularly the interior of the vehicle.

[0066] Furthermore, in Examples 1 to 5, the third lens L3 is a glass lens, which allows for sufficient suppression of focus shift due to changes in environmental temperature. Furthermore, in Examples 1 to 5, the third lens L3 has the largest positive power in the imaging lens system 11, which allows for sufficient suppression of focus shift due to changes in environmental temperature. Table 12 shows the focus shift (μm) associated with changes in environmental temperature for the focal length f of the imaging lens system 11 in Examples 1 to 5. Table 12 also shows the focus shift on the optical axis from the focal length f at a room temperature of 25°C. The barrel and housing material used to calculate the focus shift for the focal length f shown in Table 12 is XYRON XP640 manufactured by Asahi Kasei Corporation. As shown in Table 12, the focus shift for Examples 1 to 5 was sufficiently suppressed due to changes in environmental temperature. The focus shift for the focal length f shown in Table 12 was calculated using a design wavelength of 850 nm for Examples 1, 2, 4, and 5, and a design wavelength of 940 nm for Example 3. [Table 12]

[0067] Furthermore, in Examples 1 to 5, the value of f3 / f satisfies the above conditional expression (2), so that various aberrations such as spherical aberration and lateral aberration can be suitably corrected in the third lens L3. In fact, in Examples 1 to 5, various aberrations can be suitably reduced, as shown in Figures 2, 4, 6, 8, and 10.

[0068] Furthermore, in Examples 1 to 5, the value of f12 / f satisfies the above-mentioned conditional expression (3), so that various aberrations such as distortion and lateral aberration can be suitably corrected in the first lens and the second lens L2. In fact, in Examples 1 to 5, various aberrations can be suitably reduced, as shown in Figures 2, 4, 6, 8, and 10.

[0069] Furthermore, in Examples 1 to 5, the value of f2 / f satisfies the above conditional expression (4), so that various aberrations such as spherical aberration and lateral aberration can be suitably corrected in the second lens L2. In fact, in Examples 1 to 5, various aberrations can be suitably reduced, as shown in Figures 2, 4, 6, 8, and 10.

[0070] Furthermore, in Examples 1 to 5, the value of f5 / f satisfies the above conditional expression (5), so that the fifth lens L5 can suitably correct various aberrations such as lateral aberration and curvature of field. In fact, in Examples 1 to 5, various aberrations can be suitably reduced, as shown in Figures 2, 4, 6, 8, and 10.

[0071] Furthermore, in Examples 1 to 5, the value of f6 / f satisfies the above conditional expression (6), so that the sixth lens L6 can appropriately correct various aberrations such as field curvature and distortion. In fact, in Examples 1 to 5, various aberrations can be appropriately reduced, as shown in Figures 2, 4, 6, 8, and 10.

[0072] Furthermore, in Examples 1 to 5, the value of WL satisfies the above conditional expression (7), so that infrared light can be detected, enabling sensing at night or in bad weather.

[0073] In addition, in Examples 1 to 5, the value of the half angle of view ω satisfies the above conditional expression (8), and the imaging lens system 11 has a wide enough angle of view for sensing the interior of a vehicle, especially the interior of a vehicle.

[0074] Furthermore, by providing the camera module 10 with the imaging lens system 11, it is possible to provide a camera module 10 that has sufficient brightness and angle of view for monitoring the interior of a vehicle at night.

[0075] (Embodiment 3) FIG. 11 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. 11 illustrates an example of 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 installed 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 installed near an inner rearview mirror inside the vehicle 40. The third imaging device 50c may be installed on the dashboard or in the instrument panel 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 captures images of the left rear side and a right side camera that captures images of the right rear side.

[0076] An image signal of an image captured by the imaging device 50 may be output to an information processing device 42 and / or a display device 43, etc., 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 the image signal acquired by the imaging device 50 and recognizes various objects in the captured image to assist the driver in driving. The information processing device 42 may include, but is not limited to, a navigation system, a collision damage mitigation braking system, a vehicle-to-vehicle distance control device, a lane departure warning system, etc. The display device 43 displays an image processed and output by the information processing device 42, but can also receive an image signal 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, to a driver or other occupant, an image signal output from the imaging device 50, which captures an image from a position difficult for the driver to view, such as a rear camera.

[0077] Fig. 12 shows the configuration of an imaging device 50 that constitutes the in-vehicle system of Fig. 11. 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.

[0078] The control unit 52 controls the camera module 10 and processes the electrical signal 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). The PLD may include a field-programmable gate array (FPGA). The control unit 52 may be either an SoC (system-on-a-chip) or a SiP (system in a package) in which one or more processors work together.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] The imaging data may be read by the camera module 10 for all pixels and imported into the control unit 52 as a captured image. A captured image read out for 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 imported as a captured image. In other words, the imaging data may be read out from pixels in a predetermined capture range. The imaging data read out from pixels in the predetermined capture range may be imported 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 image sensor 12 may capture an image of a predetermined capture range from the subject image formed via the imaging lens system 11.

[0083] 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. [Explanation of symbols]

[0084] 10 Camera Module 11 Imaging lens system 12 Image sensor 40 Vehicles (moving objects) 42 Information processing equipment (processing equipment) 43 Display device (output device) 50 Imaging device 52 Control section L1 First lens L2 Second lens L3 Third lens L4 4th lens L5 Fifth lens L6 6th lens STOP Aperture Gf front group Gr rear group FILTER Infrared transmission filter IMG Image plane OA optical axis

Claims

1. The optical system is substantially composed of six lenses, which are, in order from the object side to the image side, a front group, an aperture stop, and a rear group, and which comprise a first lens element having a negative power and a concave surface on its image side facing the image side, a second lens element having a concave surface on its object side facing the object side, a third lens element having a positive power, a fourth lens element having a power, a fifth lens element having a power, and a sixth lens element having a power, When the focal length of the first lens is defined as f1 and the focal length of the entire optical system is defined as f, the following conditional expression (1) is satisfied: Imaging lens system. -3.0<f1 / f<-1.0...(1)

2. The imaging lens system of claim 1 , wherein the third lens is a glass lens.

3. The imaging lens system of claim 1 , wherein the third lens has the greatest positive power.

4. When the focal length of the third lens is defined as f3, the following conditional expression (2) is satisfied: The imaging lens system according to claim 1 . 1.2<f3 / f<2.0...(2)

5. 2. The imaging lens system according to claim 1, wherein when a composite focal length of the first lens and the second lens is defined as f12, the following conditional expression (3) is satisfied: -2.0<f12 / f<-1.3...(3)

6. The imaging lens system according to claim 1 , wherein the second lens, the fourth lens, the fifth lens, and the sixth lens are plastic lenses.

7. 2. The imaging lens system according to claim 1, wherein when the focal length of the second lens is defined as f2, the following conditional expression (4) is satisfied: -30<f2 / f<-5...(4)

8. 2. The imaging lens system according to claim 1, wherein the following conditional expression (5) is satisfied when the focal length of the fifth lens is defined as f5: 1.5<f5 / f<7...(5)

9. 2. The imaging lens system according to claim 1, wherein the following conditional expression (6) is satisfied when the focal length of the sixth lens is defined as f6: 3<f6 / f<50...(6)

10. 2. The imaging lens system according to claim 1, wherein the following conditional expression (7) is satisfied when a design wavelength of the imaging lens system is defined as WL: 800nm<WL<1000nm...(7)

11. 2. The imaging lens system according to claim 1, wherein the following conditional expression (8) is satisfied when a half angle of view of the imaging lens system is defined as ω: ω>60°...(8)

12. 12. A camera module comprising: the imaging lens system according to claim 1; and an imaging element that converts light collected through the imaging lens system into an electrical signal.

13. An in-vehicle system mounted on a vehicle, a camera module according to claim 12; an information processing device that processes a captured image output from the imaging element of the camera module and recognizes an object in the captured image; An in-vehicle system comprising:

14. A moving body equipped with the in-vehicle system according to claim 13, the in-vehicle system further includes an output device that outputs information to an occupant; The mobile body is characterized in that the information processing device is configured to output the recognition information of the object to the output device.

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