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

Abstract

To provide a wide-angle, high-resolution image capturing lens system which offers sufficient brightness for the sensing function during nighttime and in bad weather such as rain and fog, and to provide a camera module, in-vehicle system, and mobile vehicle.SOLUTION: An image capturing lens system 11 disclosed herein comprises a front group Gf, an aperture stop STOP, and a rear group Gr arranged in order from the object side to the image side and substantially consists of seven lenses including: a first lens L1 with negative power having a concave surface on the image side; a second lens L2 with power having a concave surface on the object side; a third lens L3 with positive power having a convex surface on the image side, where the third lens constitutes a cemented lens with the second lens L2; a fourth lens L4 with positive power; a fifth and sixth lenses L5, L6, of which one has negative power and the other has positive power; and a seventh lens L7 with positive power having a convex surface on the object side. Two adjacent lenses of the rear group Gr constitute a cemented lens. The image capturing lens system satisfies conditional expressions (1) and (2).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] In recent years, cameras mounted on vehicles are increasingly required to have a sensing function for detecting people and objects. In addition, the camera must be bright enough to enable sensing at night and in bad weather such as rain and fog. For this reason, there is a demand for imaging lenses with small F-numbers, high brightness, and high resolution. Patent Document 1 describes a lens system for an in-vehicle sensing camera that is made up of seven lenses and has an F-number of 1.59 to 1.66 and a total angle of view of 116° to 123°. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7020938 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 1.59 to 1.66, which is relatively dark and may be insufficient for sensing at night or in bad weather. In addition, the imaging lens system described in Patent Document 1 has an angle of view of 116° to 123°, which is insufficient for sensing a wide range of roads, traffic lights, pedestrians, etc.

[0005] The present invention has been made in consideration of these problems, and has an object to provide an imaging lens system, a camera module, an in-vehicle system, and a moving body that have sufficient brightness for sensing functions at night and in bad weather such as rain and fog, and have a wide angle of view and high resolution. [Means for solving the problem]

[0006] An imaging lens system of one embodiment is composed of substantially seven lenses, which are, in order from the object side to the image side, a front group, an aperture stop, and a rear group, and comprises a first lens having a negative power and a concave surface on the image side facing the image side, a second lens having a power and a concave surface on the object side facing the object side, a third lens having a positive power and a convex surface on the image side facing the image side, a fourth lens having positive power, a fifth lens and a sixth lens, one of which has negative power and the other has positive power, and a seventh lens having a convex surface on the object side facing the object side and positive power. the aperture stop is disposed between the third lens and the fourth lens, or between the fourth lens and the fifth lens, the second lens and the third lens form a cemented lens, any two adjacent lenses in the rear group constitute a cemented lens, When the refractive index of the first lens with respect to the d-line is defined as nd1 and the refractive index of the second lens with respect to the d-line is defined as nd2, the following conditional expressions (1) and (2) are satisfied. nd1>1.7 (1) nd2>1.9 (2) Effect 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 for sensing functions at night and in bad weather such as rain and fog, and have a wide angle of view and high resolution. [Brief description of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view showing a configuration of a camera module and an imaging lens system according to a first embodiment. [Diagram 2] 3A to 3C are diagrams showing spherical aberration (longitudinal aberration), field curvature, distortion, and lateral chromatic aberration in the imaging lens system of Example 1. [Diagram 3] FIG. 11 is a cross-sectional view showing the configuration of a camera module and an imaging lens system according to a second embodiment. [Figure 4] 11A to 11C are diagrams showing spherical aberration (longitudinal aberration), field curvature, distortion, and lateral chromatic aberration in the imaging lens system of Example 2. [Diagram 5] FIG. 11 is a cross-sectional view showing the configuration of a camera module and an imaging lens system according to a third embodiment. [Figure 6] 11A to 11C are diagrams showing spherical aberration (longitudinal aberration), field curvature, distortion, and lateral chromatic aberration in the imaging lens system of Example 3. [Figure 7] FIG. 11 is a cross-sectional view showing the configuration of a camera module and an imaging lens system according to a fourth embodiment. [Figure 8] 11A to 11C are diagrams showing spherical aberration (longitudinal aberration), field curvature, distortion, and lateral chromatic aberration in the imaging lens system of Example 4. [Figure 9] FIG. 11 is a cross-sectional view showing the configuration of a camera module and an imaging lens system according to a fifth embodiment. [Figure 10] 13A to 13C are diagrams showing spherical aberration (longitudinal aberration), field curvature, distortion, and lateral chromatic aberration 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 a configuration of an imaging device that constitutes the in-vehicle system of FIG. 11. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment 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 ensures healthy lives and promotes welfare for all people of all ages, and targets "3.6 By 2020, halve the number of global road traffic fatalities and injuries." in "3. Health and well-being for all" of the Sustainable Development Goals (SDGs) advocated by the United Nations. In addition, this embodiment contributes to the development of resilient infrastructure, and targets "9. Build resilient infrastructure, promote industry, innovation and infrastructure, and promote economic development and human welfare, with a focus on affordable and equitable access for all." in "9. Infrastructure and infrastructure." in 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 seven 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 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 power and a concave surface on the object side facing the object side, a third lens having a positive power and a convex surface on the image side facing the image side, a fourth lens having positive power, a fifth lens and a sixth lens, one of which has negative power and the other has positive power, and a seventh lens having a convex surface on the object side facing the object side and positive power. the aperture stop is disposed between the third lens and the fourth lens, or between the fourth lens and the fifth lens; the second lens and the third lens form a cemented lens, Any two adjacent lenses in the rear group constitute a cemented lens, When the refractive index of the first lens for the d-line is defined as nd1 and the refractive index of the second lens for the d-line is defined as nd2, the following conditional expressions (1) and (2) are satisfied. nd1>1.7 (1) nd2>1.9 (2)

[0010] This makes it possible to provide an imaging lens system that has sufficient brightness for sensing functions even at night or in bad weather such as rain or fog, and has a wide angle of view and high resolution. Specifically, when the F value (F number, Fno) is lowered, the diameter of the light beam incident on the imaging lens system becomes larger, and therefore aberration correction is required. Also, when the angle of view is wider, the effective diameter of the light beam incident on the first lens becomes wider, and therefore aberration correction is required. By satisfying the above conditional formula (1), various aberrations such as field curvature and distortion aberration can be corrected, and a bright, wide-angle, high-resolution imaging optical system can be realized. More specifically, when the value of nd1 is 1.7 or less, the refractive index of the first lens is too small, and various aberrations such as field curvature and distortion aberration in the peripheral area within the effective diameter of the first lens cannot be sufficiently corrected, and it becomes difficult to realize a bright, wide-angle, high-resolution imaging lens system. The value of nd1 is more preferably 1.72 or more, 1.76 or more, 1.85 or more, and further preferably 1.88 or more. Moreover, by satisfying the above conditional formula (2), the axial chromatic aberration and the chromatic aberration of magnification can be corrected, and a bright, wide-angle, high-resolution imaging optical system can be realized. More specifically, when the value of nd2 is 1.9 or less, the negative power of the second lens is too weak, and the cemented lens consisting of the second lens and the third lens cannot sufficiently correct various aberrations such as the axial chromatic aberration and the chromatic aberration of magnification, making it difficult to realize a bright, wide-angle, high-resolution imaging lens system. The value of nd2 is more preferably 1.94 or more, and even more preferably 2.00 or more. Therefore, when the imaging lens system satisfies conditional expressions (1) and (2), it is possible to provide an imaging lens system that has sufficient brightness for sensing functions at night and in bad weather such as rain and fog, and has a wide angle of view and high resolution.

[0011] It is also preferable that the fifth lens and the sixth lens form a cemented lens in the rear group. As a result, the cemented lens consisting of the fifth lens and the sixth lens can correct various aberrations such as axial chromatic aberration and lateral chromatic aberration, thereby achieving a bright, wide-angle, and high-resolution imaging lens system.

[0012] It is also preferable that the first lens is an aspheric lens. This makes it possible to suitably correct various aberrations such as field curvature in the first lens, thereby achieving a bright, wide-angle, and high-resolution imaging lens system.

[0013] Furthermore, when the combined focal length of the second and third lenses is defined as f23, and the focal length of the entire optical system is defined as f, it is preferable that the imaging lens system satisfies the following conditional expression (3): 5<|f23 / f|<80 ···(3) When the imaging lens system satisfies the above conditional formula (3), the axial chromatic aberration and the lateral chromatic aberration can be suitably corrected, and an imaging lens system that is bright, has a wide angle of view, and has high resolution can be realized. Specifically, when the value of |f23 / f| is 5 or less, the combined focal length of the cemented lens is too short with respect to the focal length of the entire optical system, in other words, the power of the cemented lens is too strong, and the axial chromatic aberration and the lateral chromatic aberration are overcorrected. When the value of |f23 / f| is 80 or more, the combined focal length of the cemented lens is too long with respect to the focal length of the entire optical system, in other words, the power of the cemented lens is too weak, and the correction of the axial chromatic aberration and the lateral chromatic aberration is insufficient. The value of |f23 / f| is more preferably 6.0 or more, 8.0 or more, 13.5 or more, and further preferably 17.0 or more. The value of |f23 / f| is more preferably 70.0 or less.

[0014] When the composite focal length of the fifth lens and the sixth lens is defined as f56 and the focal length of the entire optical system is defined as f, it is preferable that the following conditional expression (4) be satisfied. 5<|f56 / f|<500 ···(4) When the imaging lens system satisfies the above conditional formula (4), the axial chromatic aberration and the lateral chromatic aberration can be suitably corrected, and an imaging lens system that is bright, has a wide angle of view, and has high resolution can be realized. Specifically, when the value of |f56 / f| is 5 or less, the combined focal length of the cemented lens is too short with respect to the focal length of the entire optical system, in other words, the power of the cemented lens is too strong, and the axial chromatic aberration and the lateral chromatic aberration are overcorrected. When the value of |f56 / f| is 500 or more, the combined focal length of the cemented lens is too long with respect to the focal length of the entire optical system, in other words, the power of the cemented lens is too weak, and the correction of the axial chromatic aberration and the lateral chromatic aberration is insufficient. The value of |f56 / f| is more preferably 7.1 or more, 7.6 or more, 18.9 or more, and even more preferably 27.0 or more.

[0015] In addition, the fourth lens and the seventh lens are preferably aspherical lenses. By using the fourth lens as an aspherical lens, various aberrations such as spherical aberration and lateral aberration can be corrected, and a bright, wide-angle, high-resolution imaging lens system can be realized. In addition, by using the seventh lens as an aspherical lens, various aberrations such as lateral aberration and field curvature can be corrected, and a bright, wide-angle, high-resolution imaging lens system can be realized.

[0016] Furthermore, when the focal length of the seventh lens is defined as f7 and the focal length of the entire optical system is defined as f, it is preferable that the following conditional expression (5) be satisfied. 3 <f7 / f<5 ···(5) When the imaging lens system satisfies the above conditional formula (5), the seventh lens can appropriately correct the curvature of field, and a bright imaging lens system with high resolution can be realized. Specifically, when the value of f7 / f is 3 or less, the focal length of the seventh lens is too short with respect to the focal length of the entire optical system, in other words, the positive power of the seventh lens is too strong, and the curvature of field is overcorrected. The value of f7 / f is more preferably 3.2 or more, and even more preferably 3.5 or more. When the value of f7 / f is 5 or more, the focal length of the seventh lens is too long with respect to the focal length of the entire optical system, in other words, the positive power of the seventh lens is too weak, and the curvature of field cannot be sufficiently corrected. The value of f7 / f is more preferably 4.4 or less, and even more preferably 4.1 or less.

[0017] In addition, the imaging lens system has a linear expansion coefficient of the lens cemented in the front group at temperatures between -30°C and 70°C of AF(10 -7 / ℃), and the linear expansion coefficient of the lens cemented in the rear group at temperatures between -30℃ and 70℃ is AR(10 -7 When the amount of temperature change T (°C) from a reference temperature of 20°C is defined as 50 (°C), and the larger of the effective diameters of the cemented surfaces of the lenses arranged on the object side and the cemented surfaces of the lenses arranged on the image side in the cemented lenses in the front and rear groups is defined as Φ (mm), it is preferable to satisfy the following conditional formula (6): |AF-AR|×T×Φ<0.001 ···(6) When the imaging lens system satisfies the above conditional expression (6), stress generated in the adhesive on the cemented surfaces of the cemented lenses in the front group and the rear group can be suppressed, and peeling of the cemented lenses due to temperature changes can be suppressed. The value of |AF-AR|×T×Φ is more preferably 0.0009 or less, 0.0005 or less, 0.0003 or less, 0.0002 or less, and even more preferably 0.0001 or less.

[0018] When the refractive index of the third lens with respect to the d-line is defined as nd3, it is preferable that the following conditional expression (7) be satisfied. nd3>1.85 (7) When the imaging lens system satisfies the above conditional formula (7), the axial chromatic aberration and lateral chromatic aberration can be corrected, and a bright imaging optical system with a wide angle of view and high resolution can be realized. More specifically, when the value of nd3 is 1.85 or less, the positive power of the third lens is too weak, and the cemented lens consisting of the second lens and the third lens cannot sufficiently correct various aberrations such as the axial chromatic aberration and lateral chromatic aberration, making it difficult to realize a bright imaging lens system with a wide angle of view and high resolution. The value of nd3 is more preferably 1.87 or more, 1.92 or more, and even more preferably 2.00 or more.

[0019] (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. This makes it possible to provide a wide-angle, high-resolution camera module that has sufficient brightness for sensing functions at night and in bad weather such as rain and fog.

[0020] 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 a 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).

[0021] 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 an image forming position (focal position) of the imaging lens system 11.

[0022] The imaging lens system 11 according to the first embodiment is composed of, in order from the object side to the image side, a front group Gf consisting of a first lens L1, a second lens L2, and a third lens, an aperture stop (STOP), and a rear group Gr consisting of a fourth lens L4, a fifth lens L5, a sixth lens L6, and a seventh lens. The imaging surface of the imaging lens system 11 is indicated by IMG. The second lens L2, the third lens L3, the fifth lens L5, and the sixth lens L6 are spherical glass lenses. The first lens L1, the fourth lens L4, and the seventh lens L7 are aspherical glass lenses. If necessary, an optical filter (such as an infrared transmission filter, a visible / infrared bandpass filter, or an infrared cut filter) may be disposed between the imaging lens system 11 and the imaging element 12. In this specification, an example in which an infrared cut filter (IRCF) is disposed between the imaging lens system 11 and the imaging element 12 will be described.

[0023] The first lens L1 is a meniscus lens having negative power. The object side surface S1 of the first lens L1 has an aspheric shape with a convex surface facing the object side. The image side surface S2 of the first lens L1 has an aspheric shape with a concave surface facing the image side.

[0024] The second lens L2 has a negative power. The object side surface S3 of the second lens L2 has a spherical shape with a concave surface facing the object side. The image side surface S4 of the second lens L2 has a spherical shape with a concave surface facing the image side.

[0025] The third lens L3 has a positive power. The object side surface S6 of the third lens L3 has a spherical shape with a convex surface facing the object side. The image side surface S7 of the third lens L3 has a spherical shape with a convex surface facing the image side.

[0026] The aperture STOP is an aperture that determines the F-number (F number, Fno) of the lens system. The aperture STOP is disposed between the third lens L3 and the fourth lens L4.

[0027] The fourth lens L4 has a positive power. The object side surface S8 of the fourth lens L4 has an aspheric shape with a convex surface facing the object side. The image side surface S9 of the fourth lens L4 has an aspheric shape with a convex surface facing the image side.

[0028] The fifth lens L5 has a positive power. The object side surface S10 of the fifth lens L5 has a spherical shape with a convex surface facing the object side. The image side surface S11 of the fifth lens L5 has a spherical shape with a convex surface facing the image side.

[0029] The sixth lens L6 has a negative power. The object side surface S12 of the sixth lens L6 has a spherical shape with a concave surface facing the object side. The image side surface S13 of the sixth lens L6 has a spherical shape with a concave surface facing the image side.

[0030] The seventh lens L7 has a positive power. An object side surface S14 of the seventh lens L7 has an aspheric shape with a convex surface facing the object side. Also, an image side surface S15 of the seventh lens L7 has an aspheric shape with a concave surface facing the image side.

[0031] The infrared cut filter (IRCF) is a filter for cutting light in the infrared region. When designing the imaging lens system 11, the infrared cut filter is treated as being integrated with the imaging lens system 11. However, the infrared cut filter is not an essential component of the imaging lens system 11. The infrared cut filter is disposed on the image side of the seventh lens L7. Furthermore, a sensor cover glass may be placed between the infrared cut filter and the imaging element 12 to prevent dust from adhering to the imaging element 12.

[0032] Table 1 shows lens data for each lens surface in the imaging lens system 11 of Example 1. In Table 1, the lens data includes the radius of curvature (mm) of each surface, the surface spacing (mm) on the optical axis OA, the refractive index nd for the d-line, and the Abbe number vd for the d-line. In Table 1, a surface marked with an "*" indicates that it is an aspheric surface. In the imaging lens system 11 of Example 1, the F-number is 1.28, and the total angle of view (2ω) is 145.3°.

[0033] [Table 1]

[0034] The aspheric shape used on the lens surface is expressed as follows: Z is the amount of sag, c is the inverse of the radius of curvature, k is the cone 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 Then, it is expressed by the following equation.

number

[0035] Table 2 shows aspheric coefficients for defining the aspheric shape of the lens surface that is made aspheric in the imaging lens system 11 of Example 1. Note that in Table 2, for example, "-6.630326E-04" corresponds to "-6.630326×10 -4 The same applies to the numerical expressions in the following tables.

[0036] [Table 2]

[0037] Next, aberration will be described with reference to the drawings. Fig. 2 shows diagrams of spherical aberration (longitudinal aberration), field curvature, distortion, and lateral chromatic aberration in the imaging lens system 11 of the first embodiment. In the longitudinal aberration diagram of Fig. 2(A), the horizontal axis indicates the position where the light ray intersects with the optical axis OA, and the vertical axis indicates the passing height of the light ray on the entrance pupil. Fig. 2(A) also shows the simulation results for the d-line, C-line, and F-line. In the field curvature diagram of Fig. 2(B), the horizontal axis indicates the distance in the optical axis OA direction, and the vertical axis indicates the image height (angle of view). In the field curvature diagram of Fig. 2(B), Sagittal indicates the image formation position of the sagittal ray bundle, and Tangential indicates the image formation position of the tangential ray bundle. Fig. 2(B) also shows the simulation results for the d-line. In the distortion diagram of Fig. 2(C), the horizontal axis indicates image distortion (%) and the vertical axis indicates image height (angle of view), and Fig. 2(C) shows the simulation results for the d-line. In addition, in the magnification chromatic aberration diagram of Fig. 2(D), the horizontal axis indicates the amount of magnification chromatic aberration, and the vertical axis indicates the image height (angle of view). Fig. 2(D) also shows the simulation results for the d-line, C-line, and F-line.

[0038] Example 2 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 seventh lens L7 has a positive power, the object side surface S14 of the seventh lens L7 has an aspheric shape with a convex surface facing the object side, and the image side surface S15 of the seventh lens L7 has an aspheric shape with a convex surface facing the image side. The configuration of the imaging lens system 11 according to Example 2 other than the seventh lens L7 is the same as that of Example 1, so the description thereof will be omitted. Hereinafter, characteristic data of the imaging lens system 11 according to Example 2 will be described.

[0039] 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, in the imaging lens system 11 of Example 2, the F-number is 1.28, and the total angle of view (2ω) is 151.9°.

[0040] [Table 3]

[0041] Table 4 shows aspheric coefficients for defining the aspheric shape of the lens surface that is made aspheric in the imaging lens system 11 of Example 2. In Table 4, the aspheric shape adopted for the lens surface is expressed by the same formula as in Example 1.

[0042] [Table 4]

[0043] 4 shows diagrams of spherical aberration (longitudinal aberration), field curvature, distortion, and lateral chromatic aberration 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.

[0044] Example 3 5 is a cross-sectional view showing a camera module 10 according to Example 3. The imaging lens system 11 according to Example 3 has a lens configuration similar to that of Example 1, and therefore the description thereof will be omitted. The characteristic data of the imaging lens system 11 according to Example 3 will be described below.

[0045] Table 5 shows lens data for each lens surface of the imaging lens system 11 according to Example 3. The items shown in Table 5 are the same as those in Table 1, and therefore their explanation will be omitted. Furthermore, in the imaging lens system 11 of Example 3, the F-number is 1.20, and the total angle of view (2ω) is 144.5°.

[0046] [Table 5]

[0047] Table 6 shows aspheric coefficients for defining the aspheric shape of the lens surface that is made aspheric in the imaging lens system 11 of Example 3. In Table 6, the aspheric shape adopted for the lens surface is expressed by the same formula as in Example 1.

[0048] [Table 6]

[0049] Fig. 6 shows diagrams of spherical aberration (longitudinal aberration), field curvature, distortion, and lateral chromatic aberration 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.

[0050] Example 4 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, an aperture (STOP) is disposed between the fourth lens L4 and the fifth lens L5. Since the configuration of the imaging lens system 11 according to Example 4 other than the arrangement position of the aperture is the same as that of Example 1, the description thereof will be omitted. Hereinafter, characteristic data of the imaging lens system 11 according to Example 4 will be described.

[0051] 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, in the imaging lens system 11 of Example 4, the F-number is 1.20, and the total angle of view (2ω) is 146.0°.

[0052] [Table 7]

[0053] Table 8 shows aspheric coefficients for defining the aspheric shape of the lens surface that is made aspheric in the imaging lens system 11 of Example 4. In Table 8, the aspheric shape adopted for the lens surface is expressed by the same formula as in Example 1.

[0054] [Table 8]

[0055] Fig. 8 shows diagrams of spherical aberration (longitudinal aberration), field curvature, distortion, and lateral chromatic aberration 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.

[0056] 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 second lens L2 has positive power, the object side surface S3 of the second lens L2 has a spherical shape with a concave surface facing the object side, and the image side surface S4 of the second lens L2 has a spherical shape with a convex surface facing the image side. In the imaging lens system 11 according to Example 5, the third lens L3 has positive power, the object side surface S5 of the third lens L3 has a spherical shape with a concave surface facing the object side, and the image side surface S6 of the third lens L3 has a spherical shape with a convex surface facing the image side. In the imaging lens system 11 according to Example 5, the fifth lens L5 has negative power, the object side surface S10 of the fifth lens L5 has a spherical shape with a concave surface facing the object side, and the image side surface S11 of the fifth lens L5 has a spherical shape with a concave surface facing the image side. In the imaging lens system 11 according to Example 5, the sixth lens L6 has a positive power, the object side surface S12 of the sixth lens L6 has a spherical shape with a convex surface facing the object side, and the image side surface S13 of the sixth lens L6 has a spherical shape with a convex surface facing the image side. The other configurations of the imaging lens system 11 according to Example 5 are similar to those of Example 1, and therefore the description thereof will be omitted. Hereinafter, characteristic data of the imaging lens system 11 according to Example 5 will be described.

[0057] 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, in the imaging lens system 11 of Example 5, the F-number is 1.26, and the total angle of view (2ω) is 151.7°.

[0058] [Table 9]

[0059] Table 10 shows aspheric coefficients for defining the aspheric shape of the lens surface that is made aspheric in the imaging lens system 11 of Example 5. In Table 10, the aspheric shape adopted for the lens surface is expressed by the same formula as in Example 1.

[0060] [Table 10]

[0061] Fig. 10 shows diagrams of spherical aberration (longitudinal aberration), field curvature, distortion, and lateral chromatic aberration 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.

[0062] Table 11 shows the F value 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 f1 of the first lens L1, the focal length f2 of the second lens L2, the focal length f3 of the third lens L3, the focal length f4 of the fourth lens L4, the focal length f5 of the fifth lens L5, the focal length f6 of the sixth lens L6, the focal length f7 of the seventh lens L7, the refractive index nd1 of the first lens L1 to the d-line, the refractive index nd2 of the second lens L2 to the d-line, the refractive index nd3 of the third lens L3 to the d-line, the value of f7 / f, the value of |f23 / f|, the value of |f56 / f|, the value of |AF-AR|×T×Φ of the cemented lens in the front group, and the value of |AF-AR|×T×Φ of the cemented lens in the rear group. In Table 11, the unit of focal length is mm. The focal lengths shown in Table 11 were calculated using the d-line.

[0063] [Table 11]

[0064] In Examples 1 to 5, the imaging lens system 11 satisfies conditional expressions (1) and (2), and thus it is possible to provide an imaging lens system 11 that has sufficient brightness for sensing functions in bad weather such as at night and in rain or fog, and has a wide angle of view and high resolution. Specifically, in Examples 1 to 5, the F-number is 1.20 to 1.28, and the imaging lens system 11 has sufficient brightness. Also, in Examples 1 to 5, as shown in Figs. 2, 4, 6, 8, and 10, various aberrations can be suitably reduced. Therefore, in Examples 1 to 5, the imaging lens system 11 has high resolution. Also, in Examples 1 to 5, the total angle of view (2ω) is 144.5° to 151.9°, and the imaging lens system 11 has a wide angle of view that is sufficient for sensing vehicles.

[0065] In addition, in Examples 1 to 5, the fifth lens L5 and the sixth lens L6 form a cemented lens in the rear group Gr, and the cemented lens can effectively correct axial chromatic aberration and lateral chromatic aberration. In fact, in Examples 1 to 5, chromatic aberration can be effectively reduced, as shown in Figs. 2(D), 4(D), 6(D), 8(D), and 10(D).

[0066] In addition, in Examples 1 to 5, the first lens L1 is an aspheric lens, so that various aberrations such as field curvature and distortion can be suitably corrected in the first lens L1. In fact, in Examples 1 to 5, various aberrations can be suitably reduced as shown in Figures 2, 4, 6, 8, and 10.

[0067] In addition, in Examples 1 to 5, the value of |f23 / f| satisfies the above conditional expression (3), so that the cemented lens consisting of the second lens L2 and the third lens L3 can appropriately correct the axial chromatic aberration and the chromatic aberration of magnification. In fact, in Examples 1 to 5, chromatic aberration can be appropriately reduced, as shown in Figures 2(D), 4(D), 6(D), 8(D), and 10(D).

[0068] In addition, in Examples 1 to 5, the value of |f56 / f| satisfies the above conditional expression (4), so that the cemented lens consisting of the fifth lens L5 and the sixth lens L6 can appropriately correct the axial chromatic aberration and the lateral chromatic aberration. In fact, in Examples 1 to 5, as shown in Figures 2(D), 4(D), 6(D), 8(D), and 10(D), the chromatic aberration can be appropriately reduced.

[0069] In addition, in Examples 1 to 5, the fourth lens L4 and the seventh lens L7 are aspheric lenses, so that the fourth lens L4 can appropriately correct various aberrations such as spherical aberration and lateral aberration, and the seventh lens L7 can appropriately correct various aberrations such as lateral aberration and curvature of field. In fact, in Examples 1 to 5, various aberrations can be appropriately reduced as shown in Figures 2, 4, 6, 8, and 10.

[0070] In addition, in Examples 1 to 5, the value of f7 / f satisfies the above conditional expression (5), so that the field curvature can be suitably corrected in the seventh lens L7. In fact, in Examples 1 to 5, as shown in Figures 2(B), 4(B), 6(B), 8(B), and 10(B), the field curvature can be suitably reduced.

[0071] In addition, in Examples 1 to 5, the value of |AF-AR|×T×Φ satisfies the above-mentioned conditional formula (6), so that stress generated in the adhesive on the cemented surface between the second lens L2 and the third lens L3 and the cemented surface between the fifth lens L5 and the sixth lens L6 can be suppressed, and peeling of the cemented lenses due to temperature changes can be suppressed.

[0072] In addition, in Examples 1 to 5, the nd3 value satisfies the above conditional formula (7), so that the axial chromatic aberration and lateral chromatic aberration can be corrected, and a bright, wide-angle, high-resolution imaging optical system can be realized. In fact, in Examples 1 to 5, chromatic aberration can be suitably reduced, as shown in Figures 2(D), 4(D), 6(D), 8(D), and 10(D).

[0073] 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 for sensing functions even at night or in bad weather such as rain or fog, and has a wide angle of view and high resolution.

[0074] (Embodiment 3) FIG. 11 is a schematic diagram of a vehicle 40 equipped with an on-board 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 into an electrical signal. As shown in the figure, the imaging device 50 can be mounted on the vehicle 40, and FIG. 11 is an example of an arrangement illustrating a 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 on-board camera, and can be installed in various places on the vehicle 40. For example, the first imaging device 50a may be arranged on or near the front bumper as a camera that monitors the front when the vehicle 40 is traveling. The second imaging device 50b that monitors the front may be arranged near an inner rearview mirror inside the vehicle 40. The third imaging device 50c may be arranged on the dashboard or in the instrument panel as a camera that monitors the driving situation of the driver. The fourth imaging device 50d may be installed at the rear of the vehicle 40 for rear monitoring 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 the left rear side and a right side camera that captures the right rear side.

[0075] 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 in 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 in 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 includes, but is not limited to, a navigation device, a collision damage mitigation brake device, a vehicle distance control device, and a lane departure warning device. 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 employ, but is not limited to, a liquid crystal display (LCD), an organic EL (Electro-Luminescence) display, and an inorganic EL display. The display device 43 can display an image signal output from the imaging device 50, which captures an image at a position that is difficult for the driver to view, such as a rear camera, to a passenger such as the driver.

[0076] Fig. 12 shows the configuration of an imaging device 50 constituting 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.

[0077] The control unit 52 controls the camera module 10 and processes an electrical signal output from the image sensor 12 of the camera module 10. The control unit 52 may be configured as a processor, for example. The control unit 52 may 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 integrated circuit (ASIC) may also be called an application-specific integrated circuit (ASIC). The processor may include a programmable logic device. The programmable logic device may also be called a programmable logic device (PLD). The PLD may include a field-programmable gate array (FPGA). The control unit 52 may be either a system-on-a-chip (SoC) in which one or more processors work together, or a system in a package (SiP).

[0078] 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 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 and the like for 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.

[0079] As described above, the camera module 10 captures an object image 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 called a captured image.

[0080] The imaging element 12 may be composed of, for example, 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 called imaging data.

[0081] The imaging data may be read by the camera module 10 for all pixels and taken into the control unit 52 as a captured image. The 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 taken into the control unit 52 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 taken into the capture image. The predetermined capture range may be set by the control unit 52. The camera module 10 may obtain the predetermined capture range from the control unit 52. The imaging element 12 may capture an image of a predetermined capture range of a subject image formed via the imaging lens system 11.

[0082] The present invention is not limited to the above-described embodiments, and can be modified as appropriate without departing from the spirit and scope of the present invention. For example, the imaging lens system of the present invention is not limited to use in vehicle-mounted cameras and surveillance cameras, and can also be used for other purposes, such as being mounted on small electronic devices such as mobile phones. [Explanation of symbols]

[0083] 10 Camera Module 11 Imaging lens system 12 Image sensor 40 Vehicles (mobile objects) 42 Information processing device (processing device) 43 Display device (output device) 50 Imaging device 52 Control section L1 First lens L2 Second lens L3 Third lens L4 4th lens L5 5th lens L6 6th lens L7 7th lens STOP Squeeze Gf front group Gr rear group IRCF Infrared Cut Filter IMG Image plane OA optical axis

Claims

1. and a fourth lens having a positive power and a convex surface on the image side facing the image side, a sixth lens having a negative power and a fifth lens having a positive power, and a sixth lens having a convex surface on the image side facing the image side, a seventh lens having a positive power and a convex surface on the object side facing the object side, the aperture stop is disposed between the third lens and the fourth lens, or between the fourth lens and the fifth lens, the second lens and the third lens form a cemented lens, any two adjacent lenses in the rear group constitute a cemented lens, When the refractive index of the first lens with respect to the d line is defined as nd1 and the refractive index of the second lens with respect to the d line is defined as nd2, the following conditional expressions (1) and (2) are satisfied: Imaging lens system. nd1>1.7...(1) nd2>1.9...(2)

2. 2. The imaging lens system according to claim 1, wherein the fifth lens and the sixth lens form the cemented lens of the rear group.

3. The imaging lens system of claim 1 , wherein the first lens is an aspheric lens.

4. 2. The imaging lens system according to claim 1, wherein the following conditional expression (3) is satisfied, when a composite focal length of the second lens and the third lens is defined as f, and a focal length of the entire optical system is defined as f: 5<|f23 / f|<80...(3)

5. 2. The imaging lens system according to claim 1, wherein the following conditional expression (4) is satisfied when a composite focal length of the fifth lens and the sixth lens is defined as f, and a focal length of the entire optical system is defined as f: 5<|f56 / f|<500...(4)

6. The imaging lens system of claim 1 , wherein the fourth lens and the seventh lens are aspheric lenses.

7. 2. The imaging lens system according to claim 1, wherein the following conditional expression (5) is satisfied, when the focal length of the seventh lens is defined as f7 and the focal length of the entire optical system is defined as f: 3<f7 / f<5...(5)

8. The linear expansion coefficient of the lens cemented in the front group at temperatures between -30°C and 70°C is AF(10 －７ / °C), and the linear expansion coefficient of the lens cemented in the rear group at -30°C to 70°C is AR(10 －７ 2. The imaging lens system according to claim 1 , wherein the following conditional expression (6) is satisfied when an amount of change in temperature T (° C.) from a reference temperature of 20° C. is defined as 50 (° C.) and a larger effective diameter of the effective diameter of the cemented surfaces of the lenses arranged on the object side and the image side of the cemented lens in the front group and the cemented lens in the rear group is defined as Φ (mm): |AF-AR|×T×Φ<0.001...(6)

9. 2. The imaging lens system according to claim 1, wherein the following conditional expression (7) is satisfied when the refractive index of the third lens with respect to the d-line is defined as nd3: nd3>1.85...(7)

10. 10. 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.

11. An in-vehicle system installed in a vehicle, A camera module according to claim 10; 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:

12. A moving body equipped with the in-vehicle system according to claim 11, The in-vehicle system further includes an output device for outputting information to an occupant. The mobile body is characterized in that the information processing device is configured to output recognition information of the object to the output device.

Images