Optical system and camera module

Abstract

An optical system and a camera module are provided that are equipped with a variable focus lens and are suitable for optical image stabilization. The optical system includes a first lens group, a variable-focus lens, and a second lens group, and is 5.0, where f is the effective focal length, fv is the focal length of the variable-focus lens, ih is the maximum image height, TTL is the distance from the object-side lens surface of the lens located closest to the object to the image-forming plane, Fno is the F-number, d is the distance from the optical system to a close-up object, fi is the focal length of the i-th lens from the object side, and νi is the Abbe number of the i-th lens from the object side.

Description

[Technical Field]

[0001] The present disclosure relates to optical systems and camera modules. [Background technology]

[0002] Patent Document 1 discloses a camera module. In the camera module, an optical unit forms an image of a subject. The optical unit is composed of multiple imaging lenses and a lens barrel. The lens barrel holds the multiple imaging lenses. In the camera module, a lens driving device drives the optical unit in the optical axis direction. This allows the camera module to perform an autofocus function (paragraphs 0054 and 0055).

[0003] Patent Document 2 mentions that the camera module disclosed in Patent Document 1 has a problem in that it requires a gap for the imaging lens to move in the optical axis direction by the extension amount of the full group extension method. Patent Document 2 also mentions that the camera module disclosed in Patent Document 1 has a problem in that when the camera module is equipped with a telephoto lens with a long focal length, the extension amount becomes long, the camera module becomes large, and it becomes difficult to make the camera module smaller and thinner (paragraph 0006).

[0004] Patent Document 2 discloses a camera module. In this camera module, a first lens group receives object light, and a variable-focus lens receives the object light transmitted through the first lens group. The first lens group includes two or more lenses and has positive power as a whole. The focal length of the variable-focus lens is variable. In this camera module, focusing on a close-distance object is performed by changing the focal length of the variable-focus lens. This allows for a compact and thin camera module. In this camera module, a reflecting element is disposed before the first lens group of the optical system. In this camera module, a drive mechanism is provided between the optical system and the housing or between the imaging unit and the housing. Alternatively, the reflecting element can be rotated about any two axes. This allows for optical image stabilization (paragraphs 0014, 0018, 0019, 0020, 0028, 0029, and 0040).

[0005] Patent Document 3 discloses a lens assembly having an AF function and an OIS function, in which a voice coil motor drives a liquid lens in the liquid lens assembly (paragraph 0065). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 5611533 [Patent Document 2] Japanese Patent Publication No. 2023-132712 [Patent Document 3] Patent No. 7342141 Summary of the Invention [Problem to be solved by the invention]

[0007] Chromatic aberration is a significant issue in optical systems equipped with variable-focus lenses. Particularly when the optical system is a telephoto optical system with a long focal length and optical image stabilization (OIS) is used, chromatic aberration and other aberrations become significant due to changes in the direction of the angle of view caused by the OIS. This can sometimes prevent the optical system from achieving the required optical performance.

[0008] In view of this problem, an aspect of the present disclosure is to provide an optical system and a camera module that are equipped with a variable-focus lens and suitable for performing OIS, for example. [Means for solving the problem]

[0009] An optical system according to a first aspect of the present disclosure includes a first lens group having two or more lenses, a positive overall power, and transmitting object light; a variable-focus lens having variable power, changing the variable power to focus on a close-distance object that is closer than infinity, and disposed downstream of the first lens group, transmitting the object light; and a second lens group having at least one lens, a negative overall power, disposed downstream of the variable-focus lens, and focusing the object light on an imaging unit, f: the effective focal length of the optical system; fv: the focal length of the variable-focus lens when the focusing is performed, ih: maximum image height of the optical system, TTL: the distance from the object-side lens surface of the lens arranged closest to the object side among the lenses included in the first lens group to the image plane, Fno: F number of the optical system, d: the distance from the optical system to the near object when the focusing is performed, fi: the focal length of the i-th lens from the object side among the lenses other than the variable-focus lens included in the optical system, νi: Abbe number of the i-th lens from the object side among the lenses other than the variable-focus lens included in the optical system, Σ: A symbol meaning to obtain the sum of all lenses other than the variable focal length lens included in the optical system When it is set as 5.0 < f × fv / d, ih / f < 0.44, 0.7 < TTL / f < 1.1, 2.0 < Fno < 6.0 and Σ(1 / fi × 1 / νi) < 0 is satisfied.

[0010] The camera module according to the second aspect of the present disclosure includes the optical system according to the first aspect of the present disclosure and the imaging unit, and the imaging unit photoelectrically converts the object light.

Brief Description of Drawings

[0011] [Figure 1] It is a perspective view schematically showing the camera module of Embodiment 1. [Figure 2] It is a cross-sectional view schematically showing the camera module of Embodiment 1. [Figure 3] It is a block diagram of a control system for optical shake correction (OIS) provided in the camera module of Embodiment 1. [Figure 4A] It is a configuration diagram of the optical system provided in the camera module of Embodiment 1. [Figure 4B] It is a configuration diagram of the optical system provided in the camera module of Embodiment 1. [Figure 5A] It is a configuration diagram of the optical system provided in the camera module of Embodiment 1. [Figure 5B] It is a configuration diagram of the optical system provided in the camera module of Embodiment 1. [Figure 6A] It is a configuration diagram of the optical system provided in the camera module of Embodiment 2. [Figure 6B] It is a configuration diagram of the optical system provided in the camera module of Embodiment 2. [Figure 7A] It is a configuration diagram of the optical system provided in the camera module of Embodiment 2. [Figure 7B]FIG. 10 is a configuration diagram of an optical system provided in a camera module of a second embodiment. [Figure 8A] FIG. 10 is a configuration diagram of an optical system provided in a camera module of a third embodiment. [Figure 8B] FIG. 10 is a configuration diagram of an optical system provided in a camera module of a third embodiment. [Figure 9A] FIG. 10 is a configuration diagram of an optical system provided in a camera module of a third embodiment. [Figure 9B] FIG. 10 is a configuration diagram of an optical system provided in a camera module of a third embodiment. [Figure 10A] FIG. 10 is a configuration diagram of an optical system provided in a camera module of a fourth embodiment. [Figure 10B] FIG. 10 is a configuration diagram of an optical system provided in a camera module of a fourth embodiment. [Figure 11A] FIG. 10 is a configuration diagram of an optical system provided in a camera module of a fourth embodiment. [Figure 11B] FIG. 10 is a configuration diagram of an optical system provided in a camera module of a fourth embodiment. [Figure 12A] FIG. 10 is a diagram illustrating the configuration of an optical system provided in a camera module according to a fifth embodiment. [Figure 12B] FIG. 10 is a diagram illustrating the configuration of an optical system provided in a camera module according to a fifth embodiment. [Figure 13A] FIG. 10 is a diagram illustrating the configuration of an optical system provided in a camera module according to a fifth embodiment. [Figure 13B] FIG. 10 is a diagram illustrating the configuration of an optical system provided in a camera module according to a fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the drawings, the same or equivalent elements are designated by the same reference numerals, and redundant description will be omitted.

[0013] 1. Embodiment 1 1.1 Camera module Fig. 1 is a perspective view that schematically illustrates a camera module of Embodiment 1. Fig. 2 is a cross-sectional view that schematically illustrates a camera module of Embodiment 1. Fig. 2 illustrates a cross section taken along the cutting line II-II in Fig. 1. Fig. 2 illustrates a cross section obtained by cutting the center of the camera module of Embodiment 1 in the optical axis direction of the camera module.

[0014] 1 and 2, the camera module 1 of the first embodiment receives object light emitted by an object and outputs an image signal corresponding to the received object light. The camera module 1 is a folded camera module equipped with a folded optical system. The camera module 1 performs optical image stabilization (OIS).

[0015] As shown in FIGS. 1 and 2, the camera module 1 includes a reflecting element 101, an optical system 102, an infrared cut filter 103, an imaging unit 104, and a housing 105.

[0016] The reflective element 101 is disposed closest to the object. The reflective element 101 reflects a first object beam emitted by an object and traveling along a first optical axis 111 to generate a second object beam traveling along a second optical axis 112. The reflective element 101 directs the generated second object beam traveling along the second optical axis 112 toward the optical system 102. Therefore, the reflective element 101 bends the optical path of the light rays constituting the object beam. The angle at which the reflective element 101 bends the light beam, i.e., the angle between the first optical axis 111 and the second optical axis 112, is preferably 90°. However, the angle may be an angle other than 90°. The reflective element 101 is preferably a prism with high processing accuracy. However, the reflective element 101 may also be a reflective member other than a prism. For example, the reflective element 101 may be a reflecting plate that is low in cost and requires only a small installation volume. A reflecting plate is also called a mirror.

[0017] When camera module 1 including reflective element 101 is mounted on a smartphone, the optical axis direction can be tilted from a direction perpendicular to the back surface of the smartphone to a direction parallel to the back surface, thereby making it possible to make the smartphone thinner.

[0018] The optical system 102 is disposed after the reflecting element 101, and focuses the second object light traveling along the second optical axis 112 onto the imaging plane 104a of the imaging unit 104. As a result, an image of the object is formed on the imaging plane 104a.

[0019] The infrared cut filter 103 is disposed after the optical system 102 and cuts infrared components from the second object light focused on the image forming surface 104a of the imaging unit 104. The infrared cut filter 103 is disposed in front of the image forming surface 104a. This prevents foreign matter such as dust from directly adhering to the image forming surface 104a. This prevents the second object light focused on the image forming surface 104a from being blocked by the foreign matter. This prevents the image represented by the image signal output from the camera module 1 from being degraded by the foreign matter.

[0020] The imaging unit 104 has an image plane 104a on which the second object light that has passed through the optical system 102 is focused. The imaging unit 104 is a sensor that photoelectrically converts the focused second object light and outputs an image signal corresponding to the second object light. The output image signal is processed by software and converted into an image. The imaging unit 104 is a complementary metal-oxide semiconductor (CMOS) image sensor, a charge-coupled device (CCD) image sensor, or the like.

[0021] The housing 105 directly or indirectly supports the reflecting element 101, the optical system 102, the infrared cut filter 103, and the imaging unit 104.

[0022] 1.2 Optical system As shown in FIG. 2, the optical system 102 includes a first lens group G1, a variable-focus lens VL, a second lens group G2, and an aperture stop St.

[0023] The first lens group G1 receives the second object light and transmits the received second object light. The first lens group G1 includes two or more lenses. In the first embodiment, the two or more lenses include a first lens L1 and a second lens L2. The first lens group G1 has positive power as a whole. The first lens L1 is the lens of the two or more lenses that is arranged closest to the object side and is the lens of the two or more lenses that is arranged closest to the reflecting element 101.

[0024] A reflecting element 101 is disposed before the first lens group G1. Therefore, the object light transmitted to the optical system 102 and received by the first lens group G1 is the second object light that is reflected by the reflecting element 101 and travels along the second optical axis 112.

[0025] The variable-focus lens VL is disposed after the first lens group G1 and transmits the second object light that has passed through the first lens group G1. The variable-focus lens VL has variable power. The variable-focus lens VL changes its variable power to focus on a close-distance object that is closer than infinity and emits object light. The variable-focus lens VL is a liquid lens. Therefore, the focal length of the variable-focus lens VL can be changed by changing the radius of curvature of the lens surface of the variable-focus lens VL. This enables the variable-focus lens VL to perform focusing. A liquid lens is a typical variable-focus lens and is suitable as the variable-focus lens VL in terms of size, performance, price, etc. However, the variable-focus lens VL may be a variable-focus lens other than a liquid lens. For example, the variable-focus lens VL may be a lens made of a soft polymer.

[0026] The second lens group G2 is disposed after the variable-focus lens VL, transmits the second object light that has passed through the first lens group G1, and focuses the transmitted second object light on the imaging unit 104. The second lens group G2 includes at least one lens. In the first embodiment, the at least one lens includes a third lens L3 and a fourth lens L4. The second lens group G2 has negative power as a whole.

[0027] The first lens L1, the second lens L2, the third lens L3, and the fourth lens L4 are glass lenses. Some or all of the first lens L1, the second lens L2, the third lens L3, and the fourth lens L4 may be lenses other than glass lenses. For example, some or all of the first lens L1, the second lens L2, the third lens L3, and the fourth lens L4 may be plastic lenses.

[0028] The first lens group G1, the variable focus lens VL, and the second lens group G2 are supported directly or indirectly on the housing 105 so that the optical axes of the optical system 102, the first lens group G1, the variable focus lens VL, and the second lens group G2 coincide with the second optical axis 112.

[0029] The optical system 102 includes three lens groups: a first lens group G1, a variable-focus lens VL, and a second lens group G2. The optical system 102 may include four or more lens groups.

[0030] The aperture stop St is included in the optical system 102 and limits the bundle of rays of the object light that passes through the optical system 102 .

[0031] The first lens group G1 and the imaging unit 104 are fixed to the housing 105 so that the distance between the first lens group G1 and the imaging unit 105 in the direction along the second optical axis 112 does not change when focusing on a close-range object.

[0032] 1.3 Conditions that the optical system must meet f: effective focal length of the optical system 102, fv: focal length of the variable-focus lens VL when focusing is performed, ih: maximum image height of the optical system 102, TTL: the distance from the object-side lens surface L1a of the first lens L1, which is arranged closest to the object side among the lenses included in the first lens group G1, to the imaging plane 104a of the imaging unit 104, Fno: F number of optical system 102, d: distance from the optical system 102 to a close object when focusing is performed, fi: Among the lenses other than the variable focal length lens VL included in the optical system 102, the focal length of the i-th lens from the object side, νi: Among the lenses other than the variable focal length lens VL included in the optical system 102, the Abbe number of the i-th lens from the object side, Σ: A symbol meaning to obtain the sum for all lenses other than the variable focal length lens VL included in the optical system 102 When it is set as, the optical system 102 5.0 < f × fv / d (1), ih / f < 0.44 (2), 0.7 < TTL / f < 1.1 (3), 2.0 < Fno < 6.0 (4) and Σ(1 / fi × 1 / νi) < 0 (5) is satisfied.

[0033] Conditional expression (1) defines the desirable range of the parameter f × fv / d that affects the magnitude of the change in the focal length fv of the variable focal length lens VL when focusing is performed. When the parameter f × fv / d is greater than the lower limit value of 5.0, the change in the focal length fv of the variable focal length lens VL when focusing is performed becomes smaller. Therefore, the magnification fluctuation and aberration fluctuation of the optical system 102 when focusing is performed become smaller. When the parameter f × fv / d is less than or equal to the lower limit value of 5.0, the change in the curvature of the lens surface of the variable focal length lens VL when focusing is performed becomes larger. Therefore, the magnification fluctuation and aberration fluctuation of the optical system 102 when focusing is performed become larger. Therefore, it is not desirable that the parameter f × fv / d is less than or equal to the lower limit value of 5.0.

[0034] Conditional expression (2) defines the desirable range of the ratio ih / f of the maximum image height ih to the focal length f of the optical system 102, which determines the 35 mm equivalent focal length of the optical system 102. When the ratio ih / f is smaller than the upper limit value of 0.44, the 35 mm equivalent focal length becomes 50 mm or more. Therefore, by combining the camera equipped with the camera module 1 with a camera having a 35 mm equivalent focal length of 25 mm, a zoom ratio of 2 times or more can be realized.

[0035] Conditional expression (3) defines a desirable range for the telephoto ratio TTL / f of the optical system 102. When the telephoto ratio TTL / f is equal to or less than the lower limit of 0.7, the optical system 102 becomes small. However, the aberration of the optical system 102 becomes large. Furthermore, the aberration of the optical system 102 becomes large when focusing on a close-up object. In particular, the fluctuation of the curvature of field of the optical system 102 becomes large. On the other hand, when the telephoto ratio TTL / f is equal to or greater than the upper limit of 1.0, the optical system 102 becomes large. For these reasons, it is not desirable for the telephoto ratio TTL / f to be equal to or less than 0.7 or equal to or greater than 1.0.

[0036] Conditional expression (4) defines a desirable range for the F-number Fno of the optical system 102. If the F-number Fno is equal to or less than the lower limit of 2.0, the thickness of the optical system 102 will be large. In addition, the spherical aberration and coma of the optical system 102 will increase. On the other hand, if the F-number Fno is equal to or greater than the upper limit of 6.0, the amount of light that the optical system 102 can receive will decrease. In addition, the resolution performance of the optical system 102 will decrease due to the diffraction limit. For these reasons, it is undesirable for the F-number Fno to be equal to or less than 2.0 or equal to or greater than 6.0.

[0037] Conditional expression (5) defines a desirable range for the parameter Σ(1 / fi×1 / νi), which affects the magnitude of the overall chromatic aberration of the lenses other than the variable-focus lens VL included in the optical system 102. If the parameter Σ(1 / fi×1 / νi) is equal to or greater than the upper limit of 0, the influence of chromatic aberration of the optical system 104 increases when focusing is performed. For this reason, it is not desirable for the parameter Σ(1 / fi×1 / νi) to be equal to or greater than 0.

[0038] When the optical system 102 satisfies conditional expressions (1) to (5), it is possible to prevent chromatic aberration and other aberrations from occurring significantly even when the direction of the angle of view changes due to the OIS being performed, and therefore it is possible to provide an optical system 102 that is suitable for the OIS.

[0039] 1.4 Optical image stabilization FIG. 3 is a block diagram of a control system for the OIS provided in the camera module of the first embodiment.

[0040] As shown in FIG. 3, the optical system 102 includes a detector 121 , a driver 122 , and a controller 123 .

[0041] The detector 121 detects the state of camera shake and outputs a signal according to the detected state of camera shake.

[0042] The driving device 122 drives the second lens group G2, the reflecting element 101, the entire optical system 102, or the imaging unit 104 to move the image of the object formed on the imaging surface 104a of the imaging unit 104 in a direction perpendicular to the optical axis of the optical system 102.

[0043] The controller 123 controls the driving device 122 in accordance with the output signal. The controller 123 causes the driving device 122 to drive the second lens group G2, the reflecting element 101, the entire optical system 102, or the imaging unit 104 so as to cancel out movement of the object image due to camera shake. In this way, the driving device 122 performs OIS.

[0044] When driving the second lens group G2, the driver 122 rotates the second lens group G2 around a rotation axis, thereby performing OIS. The rotation axis may be any axis. Alternatively, when driving the second lens group G2, the driver 122 moves the second lens group G2 in a direction perpendicular to the optical axis of the second lens group G2, thereby performing OIS.

[0045] When driving the reflecting element 101, the driving device 122 rotates the reflecting element 101 around a rotation axis, thereby performing OIS. The rotation axis may be any axis. When driving the reflecting element 101, the driving device 122 includes a driving unit and a holding member. The driving unit generates a driving force to drive the reflecting element 101. The holding member holds the reflecting element 101 and transmits the generated driving force to the reflecting element 101 that it holds, causing the reflecting element 101 to rotate.

[0046] When driving the entire optical system 102, the driving device 122 moves the entire optical system 102 parallel to the axis, thereby performing OIS. The axis may be any axis. When driving the entire optical system 102, the driving device 122 includes a driving unit and a holding member. The driving unit generates a driving force to drive the optical system 102. The holding member holds the optical system 102 and transmits the generated driving force to the held optical system 102, thereby moving the optical system 102.

[0047] When driving the imaging unit 104, the driving device 122 moves the imaging unit 104 parallel to an axis, thereby performing OIS. The axis may be any axis. When driving the imaging unit 104, the driving device 122 includes a driving unit and a holding member. The driving unit generates a driving force to drive the imaging unit 104. The holding member holds the imaging unit 104 and transmits the generated driving force to the imaging unit 104 it holds, thereby moving the imaging unit 104.

[0048] When driving device 122 drives reflecting element 101, the entire optical system 102, or imaging unit 104, there is a possibility that driving device 122 can be configured using a general-purpose driving device. However, when driving device 122 drives reflecting element 101, the entire optical system 102, or imaging unit 104, the driving unit provided in driving device 122 has a large size and a large weight. Therefore, driving device 122 has a large size and a large weight. Also, the power required to perform OIS becomes large.

[0049] In contrast, when the driving device 122 drives only the second lens group G2, the driving device 122 has a small size and a small weight, and the power required to perform OIS is small.

[0050] The driving device 122 may drive two or more types of driven bodies to move the image of the object in a direction perpendicular to the optical axis of the optical system 102. For example, the driving device 122 may drive a first driven body to move the image of the object in a first direction and drive a second driven body to move the image of the object in a second direction intersecting the first direction. For example, the driving device 122 may rotate the reflective element 101 around a first rotation axis to move the image of the object in the first direction and rotate the second lens group G2 around a second rotation axis to move the image of the object in the second direction. The combination of two or more types of driven bodies to be driven is not limited and is determined to be a combination suitable for achieving the specifications required of the camera module 1. When the driving device 122 drives two or more types of driven bodies for the OIS, it may be possible to narrow the driving range of each driven body compared to when the driving device 122 drives one type of driven body for the OIS. This may enable the miniaturization of the camera module 1. For example, when the driving device 122 drives the reflecting element 101 and the second lens group G2 for the OIS, the OIS in the thickness direction of the camera module 1 can be controlled by rotating the reflecting element 101. This eliminates the need for space to drive the second lens group G2 in the thickness direction. This allows the thickness of the camera module 1 to be reduced.

[0051] 1.5 Configuration diagram and lens data 4A and 4B are diagrams illustrating the configuration of an optical system provided in the camera module of Embodiment 1. Fig. 4A is a diagram illustrating the configuration when focusing at infinity, and Fig. 4B is a diagram illustrating the configuration when focusing at 1m.

[0052] 5A and 5B are diagrams illustrating the configuration of an optical system provided in the camera module of Embodiment 1. Fig. 5A is a diagram illustrating the configuration when in the normal position, and Fig. 5B is a diagram illustrating the configuration when image stabilization is performed.

[0053] 4A, 4B, 5A, and 5B, the optical system 102 includes an aperture stop St, a first lens group G1 having overall positive power, a variable-focus lens VL, and a second lens group G2 having overall negative power. Arranged in the optical system 102, in order from the object side, are the aperture stop St, the first lens group G1, the variable-focus lens VL, and the second lens group G2. The first lens group G1 is made up of a first lens L1 having positive power and a second lens L2 having negative power. The second lens group G2 is made up of a third lens L3 having positive power and a fourth lens L4 having negative power.

[0054] Table 1 shows lens data of the optical system 102 provided in the camera module 1 of the first embodiment.

[0055] [Table 1]

[0056] In Table 1, f denotes the overall focal length of the optical system 102, Fno denotes the overall F-number of the optical system 102, Ω denotes the overall half angle of view (degrees) of the optical system 102, ih denotes the overall maximum image height of the optical system 102, and TTL denotes the distance from the object-side lens surface L1a of the first lens L1, which is located closest to the reflecting element 101 among the two or more lenses provided in the first lens group G1, to the imaging unit 104. ih denotes the maximum image height at which the performance of the optical system 102 can be guaranteed. In addition, i denotes the surface number of the lens surface counted from the object side, r denotes the radius of curvature of the lens surface, t denotes the distance between the lens surfaces on the second optical axis 112, Nd denotes the refractive index for the d-line, and νd denotes the Abbe number for the d-line. In Table 1, an asterisk (*) is added after the surface number of an aspherical lens surface.

[0057] The aspherical shape of an aspherical lens surface is expressed by formula (1), where z is the position in the optical axis direction, h is the height in the direction perpendicular to the optical axis, k is the cone number, and A4, A6, A8, A10, and A12 are aspherical coefficients. This also applies to Tables 2 to 5 below.

[0058]

number

[0059] When the optical system 102 has the lens data shown in Table 1, the effective focal length f of the optical system 102 is 38.1 mm. Furthermore, when the imaging unit 104 is a 1 / 4.4-inch sensor, the 35mm equivalent focal length of the optical system 102 is approximately 400 mm. Therefore, when the telephoto side camera of a twin-lens camera is equipped with the camera module 1 and the 35mm equivalent focal length of the wide-angle side camera of the twin-lens camera is 24 mm, the zoom ratio of the twin-lens camera can be approximately 16.7 times.

[0060] When the optical system 102 has the lens data shown in Table 1, the effective focal length f of the optical system 102 is 38.1 mm. Furthermore, when the distance d from the optical system 102 to an object is 1000 mm and focusing is performed on the object, the focal length fv of the variable-focus lens VL is 161.7 mm. Furthermore, the maximum image height ih is 2.050 mm. Furthermore, the distance TTL is 32.60 mm. Furthermore, the F-number Fno is 5.0. Furthermore, the sum Σ(1 / fi × 1 / νi) of the products of the reciprocal of the lens focal length fi and the reciprocal of the lens Abbe number νi for all lenses other than the variable-focus lens VL is -9.17E-05.

[0061] Therefore, the optical system 102 satisfies the above-mentioned conditional expressions (1) to (6).

[0062] As shown in Figures 4A and 4B, in the optical system 102, the curvature of the lens surface of the variable-focus lens VL is changed, thereby changing the focal length of the variable-focus lens VL and performing focusing from infinity to close-up photography.

[0063] If the image capture unit 104 is a 1 / 4.4-inch sensor, a lens extension amount of 1.5 mm is required when focusing to a close-up shooting distance of 1 m using the full-lens extension method. In contrast, when focusing to a close-up shooting distance of 1 m is performed by changing the focal length of the variable-focus lens VL, extension of the optical system 102 is not required.

[0064] When the optical system 102 has the lens data shown in Table 1, the sum Σ(1 / fi × 1 / νi) of the products of the reciprocal of the lens focal length fi and the reciprocal of the lens Abbe number νi for all lenses other than the variable-focus lens VL takes a negative value. This allows for good correction of chromatic aberration in the optical system 102.

[0065] As shown in FIGS. 5A and 5B, in the optical system 102, a second lens group G2 is disposed after the variable-focus lens VL. By rotating the second lens group G2 about a rotation axis, the image of the object formed on the imaging plane 104a of the imaging unit 104 is moved in a direction perpendicular to the optical axis of the optical system 102, thereby performing OIS. When the optical system 102 has the lens data shown in Table 1, as shown in FIGS. 5A and 5B, when the rotation angle of the second lens group G2 is 4.1 degrees, the movement amount of the image of the object formed on the imaging plane 104a is 0.15 mm. The movement amount of the image of the object formed on the imaging plane 104a is roughly proportional to the tangent of the rotation angle of the second lens group G2. This can be easily understood by considering the properties of trigonometric functions.

[0066] 2. Embodiment 2 The following describes the differences between the second embodiment and the first embodiment. For points that are not described, the second embodiment also employs the same configuration as that employed in the first embodiment.

[0067] 6A and 6B are diagrams illustrating the configuration of an optical system provided in a camera module of embodiment 2. Fig. 6A is a diagram illustrating the configuration when focusing at infinity, and Fig. 6B is a diagram illustrating the configuration when focusing at 1m.

[0068] 7A and 7B are diagrams illustrating the configuration of an optical system provided in a camera module of embodiment 2. Fig. 7A is a diagram illustrating the configuration when in the normal position, and Fig. 7B is a diagram illustrating the configuration when image stabilization is performed.

[0069] The camera module 1 of the second embodiment can realize a twin-lens camera with a zoom ratio of approximately 10x.

[0070] Table 2 shows lens data of the optical system 102 provided in the camera module 1 of the second embodiment.

[0071] [Table 2]

[0072] When the optical system 102 has the lens data shown in Table 2, the effective focal length f of the optical system 102 is 22.9 mm. When the imaging unit 104 is a 1 / 4.4-inch sensor, the 35 mm equivalent focal length of the optical system 102 is approximately 240 mm. Therefore, when the telephoto side camera of a twin-lens camera is equipped with the camera module 1 and the 35 mm equivalent focal length of the wide-angle side camera of the twin-lens camera is 24 mm, the zoom ratio of the twin-lens camera can be increased to approximately 10 times.

[0073] When the optical system 102 has the lens data shown in Table 2, the effective focal length f is 22.9 mm. When the distance d from the optical system 102 to an object is 1000 mm and focusing is performed on the object, the focal length fv of the variable-focus lens VL is 406.4 mm. The maximum image height ih is 2.050 mm. The distance TTL is 22.10 mm. The F-number Fno is 4.0. The sum Σ(1 / fi × 1 / νi) of the products of the reciprocal of the lens focal length fi and the reciprocal of the lens Abbe number νi for all lenses other than the variable-focus lens VL is -6.82E-04.

[0074] Therefore, the optical system 102 satisfies the above-mentioned conditional expressions (1) to (6).

[0075] As shown in Figures 6A and 6B, in the optical system 102, the curvature of the lens surface of the variable-focus lens VL is changed, thereby changing the focal length of the variable-focus lens VL and performing focusing from infinity to close-up photography.

[0076] If the image capture unit 104 is a 1 / 4.4-inch sensor, a lens extension amount of 0.5 mm is required when focusing to a close-up shooting distance of 1 m using the full-lens extension method. In contrast, when focusing to a close-up shooting distance of 1 m is performed by changing the focal length of the variable-focus lens VL, extension of the optical system 102 is not required.

[0077] When the optical system 102 has the lens data shown in Table 2, the sum Σ(1 / fi × 1 / νi) of the products of the reciprocal of the lens focal length fi and the reciprocal of the lens Abbe number νi for all lenses other than the variable-focus lens VL takes a negative value. This allows for good correction of chromatic aberration in the optical system 102.

[0078] As shown in FIGS. 7A and 7B, in the optical system 102, a second lens group G2 is disposed after the variable-focus lens VL. By rotating the second lens group G2 about a rotation axis, the image of the object formed on the imaging plane 104a of the imaging unit 104 is moved in a direction perpendicular to the optical axis of the optical system 102, thereby performing OIS. When the optical system 102 has the lens data shown in Table 2, as shown in FIGS. 7A and 7B, when the rotation angle of the second lens group G2 is 5.0 degrees, the movement amount of the image of the object formed on the imaging plane 104a is 0.15 mm. The movement amount of the image of the object formed on the imaging plane 104a is roughly proportional to the tangent of the rotation angle of the second lens group G2. This can be easily understood by considering the properties of trigonometric functions.

[0079] 3. Embodiment 3 The following describes the differences between the third embodiment and the second embodiment. For points that are not described, the same configurations as those employed in the second embodiment are also employed in the third embodiment.

[0080] 8A and 8B are diagrams illustrating the configuration of an optical system provided in a camera module of embodiment 3. Fig. 8A is a diagram illustrating the configuration when focusing at infinity, and Fig. 8B is a diagram illustrating the configuration when focusing at 1m.

[0081] 9A and 9B are diagrams illustrating the configuration of an optical system provided in a camera module of embodiment 3. Fig. 9A is a diagram illustrating the configuration when in the normal position, and Fig. 9B is a diagram illustrating the configuration when image stabilization is performed.

[0082] The camera module 1 of the third embodiment has an F-number smaller than the F-number of the camera module 1 of the third embodiment.

[0083] Table 3 shows lens data of the optical system 102 provided in the camera module 1 of the third embodiment.

[0084] [Table 3]

[0085] When the optical system 102 has the lens data shown in Table 3, the effective focal length f of the optical system 102 is 22.9 mm. When the imaging unit 104 is a 1 / 4.4-inch sensor, the 35 mm equivalent focal length of the optical system 102 is approximately 240 mm. Therefore, when the telephoto side camera of a twin-lens camera is equipped with the camera module 1 and the 35 mm equivalent focal length of the wide-angle side camera of the twin-lens camera is 24 mm, the zoom ratio of the twin-lens camera can be increased to approximately 10x.

[0086] When the optical system 102 has the lens data shown in Table 3, the effective focal length f is 22.9 mm. Furthermore, when the distance d from the optical system 102 to an object is 1000 mm and focusing is performed on the object, the focal length fv of the variable-focus lens VL is 276.5 mm. Furthermore, the maximum image height ih is 2.050 mm. Furthermore, the distance TTL is 22.11 mm. Furthermore, the F-number Fno is 2.6. Furthermore, the sum Σ(1 / fi × 1 / νi) of the products of the reciprocal of the lens focal length fi and the reciprocal of the lens Abbe number νi for all lenses other than the variable-focus lens VL is -6.34E-04.

[0087] Therefore, the optical system 102 satisfies the above-mentioned conditional expressions (1) to (6).

[0088] As shown in Figures 8A and 8B, in the optical system 102, the curvature of the lens surface of the variable-focus lens VL is changed, thereby changing the focal length of the variable-focus lens VL and performing focusing from infinity to close-up photography.

[0089] If the image capture unit 104 is a 1 / 4.4-inch sensor, a lens extension amount of 0.5 mm is required when focusing to a close-up shooting distance of 1 m using the full-lens extension method. In contrast, when focusing to a close-up shooting distance of 1 m is performed by changing the focal length of the variable-focus lens VL, extension of the optical system 102 is not required.

[0090] When the optical system 102 has the lens data shown in Table 3, the sum Σ(1 / fi × 1 / νi) of the products of the reciprocal of the lens focal length fi and the reciprocal of the lens Abbe number νi for all lenses other than the variable-focus lens VL takes a negative value. This allows for good correction of chromatic aberration in the optical system 102.

[0091] As shown in FIGS. 9A and 9B, in the optical system 102, a second lens group G2 is disposed after the variable-focus lens VL. By rotating the second lens group G2 about a rotation axis, the image of the object formed on the imaging plane 104a of the imaging unit 104 is moved in a direction perpendicular to the optical axis of the optical system 102, thereby performing OIS. When the optical system 102 has the lens data shown in Table 3, as shown in FIGS. 9A and 9B, when the rotation angle of the second lens group G2 is 5.2 degrees, the movement amount of the image of the object formed on the imaging plane 104a is 0.15 mm. The movement amount of the image of the object formed on the imaging plane 104a is approximately proportional to the tangent of the rotation angle of the second lens group G2. This can be easily understood by considering the properties of trigonometric functions.

[0092] 4. Embodiment 4 The following describes the differences between the fourth embodiment and the first embodiment. For points that are not described, the same configurations as those employed in the first embodiment are also employed in the fourth embodiment.

[0093] 10A and 10B are diagrams illustrating the configuration of an optical system provided in a camera module of embodiment 4. Fig. 10A is a diagram illustrating the configuration when focusing at infinity, and Fig. 10B is a diagram illustrating the configuration when focusing at 1m.

[0094] 11A and 11B are diagrams illustrating the configuration of an optical system provided in a camera module of embodiment 4. Fig. 11A is a diagram illustrating the configuration when in the normal position, and Fig. 11B is a diagram illustrating the configuration when image stabilization is performed.

[0095] The camera module 1 of the fourth embodiment performs OIS by moving the second lens group G2 in a direction perpendicular to the optical axis of the second lens group G2.

[0096] Table 4 shows lens data of the optical system 102 provided in the camera module 1 of the fourth embodiment.

[0097] [Table 4]

[0098] When the optical system 102 has the lens data shown in Table 4, the effective focal length f of the optical system 102 is 38.1 mm. When the imaging unit 104 is a 1 / 4.4-inch sensor, the 35mm equivalent focal length of the optical system 102 is approximately 400 mm. Therefore, when the telephoto side camera of a twin-lens camera is equipped with the camera module 1 and the 35mm equivalent focal length of the wide-angle side camera of the twin-lens camera is 24 mm, the zoom ratio of the twin-lens camera can be approximately 16.7 times.

[0099] When the optical system 102 has the lens data shown in Table 4, the effective focal length f is 38.1 mm. When the distance d from the optical system 102 to an object is 1000 mm and focusing is performed on the object, the focal length fv of the variable-focus lens VL is 216.9 mm. The maximum image height ih is 2.050 mm. The distance TTL is 31.49 mm. The F-number Fno is 5.0. The sum Σ(1 / fi × 1 / νi) of the products of the reciprocals of the lens focal lengths fi and the reciprocals of the lens Abbe numbers νi for all lenses other than the variable-focus lens VL is -2.85E-04.

[0100] Therefore, the optical system 102 satisfies the above-mentioned conditional expressions (1) to (6).

[0101] As shown in Figures 10A and 10B, in the optical system 102, the curvature of the lens surface of the variable-focus lens VL is changed, thereby changing the focal length of the variable-focus lens VL and performing focusing from infinity to close-up photography.

[0102] If the image capture unit 104 is a 1 / 4.4-inch sensor, a lens extension amount of 1.5 mm is required when focusing to a close-up shooting distance of 1 m using the full-lens extension method. In contrast, when focusing to a close-up shooting distance of 1 m is performed by changing the focal length of the variable-focus lens VL, extension of the optical system 102 is not required.

[0103] Furthermore, when the optical system 102 has the lens data shown in Table 4, the sum Σ(1 / fi × 1 / νi) of the products of the reciprocals of the lens focal lengths fi and the reciprocals of the lens Abbe numbers νi for all lenses other than the variable-focus lens VL takes a negative value. This allows for good correction of chromatic aberration in the optical system 102.

[0104] 11A and 11B, in the optical system 102, a second lens group G2 is disposed after the variable-focus lens VL, and by moving the second lens group G2 in a direction perpendicular to the optical axis of the second lens group G2, the image of the object formed on the imaging plane 104a of the imaging unit 104 is moved in a direction perpendicular to the optical axis of the optical system 102, thereby performing OIS. When the optical system 102 has the lens data shown in Table 4, as shown in FIGS. 11A and 11B, when the movement amount of the second lens group G2 is 0.4 mm, the movement amount of the image of the object formed on the imaging plane 104a is 0.15 mm. The movement amount of the image of the object formed on the imaging plane 104a is roughly proportional to the movement amount of the second lens group G2.

[0105] 5. Embodiment 5 The following describes the differences between the fifth embodiment and the first embodiment. For points that are not described, the same configurations as those employed in the first embodiment are also employed in the fifth embodiment.

[0106] 12A and 12B are diagrams illustrating the configuration of an optical system provided in a camera module of embodiment 5. Fig. 12A is a diagram illustrating the configuration when focusing at infinity, and Fig. 12B is a diagram illustrating the configuration when focusing at 1m.

[0107] 13A and 13B are diagrams illustrating the configuration of an optical system provided in a camera module according to embodiment 5. Fig. 13A is a diagram illustrating the configuration when in the normal position, and Fig. 13B is a diagram illustrating the configuration when image stabilization is performed.

[0108] The camera module 1 of the fifth embodiment uses a different glass type for the lens from the glass type used for the lens in the first to fourth embodiments.

[0109] Table 5 shows lens data of the optical system 102 provided in the camera module 1 of the fifth embodiment.

[0110] [Table 5]

[0111] When optical system 102 has the lens data shown in Table 5, the effective focal length f of optical system 102 is 38.1 mm. Furthermore, when imaging unit 104 is a 1 / 4.4-inch sensor, the 35mm equivalent focal length of optical system 102 is approximately 400 mm. Therefore, when the telephoto side camera of a twin-lens camera is equipped with camera module 1 and the 35mm equivalent focal length of the wide-angle side camera of the twin-lens camera is 24 mm, the zoom ratio of the twin-lens camera can be approximately 16.7 times.

[0112] When the optical system 102 has the lens data shown in Table 5, the effective focal length f is 38.1 mm. Furthermore, when the distance d from the optical system 102 to an object is 1000 mm and focusing is performed on the object, the focal length fv of the variable-focus lens VL is 249.3 mm. Furthermore, the maximum image height ih is 2.050 mm. Furthermore, the distance TTL is 32.72 mm. Furthermore, the F-number Fno is 5.0. Furthermore, the sum Σ(1 / fi × 1 / νi) of the products of the reciprocals of the lens focal lengths fi and the reciprocals of the lens Abbe numbers νi for all lenses other than the variable-focus lens VL is -4.74E-04.

[0113] Therefore, the optical system 102 satisfies the above-mentioned conditional expressions (1) to (6).

[0114] As shown in Figures 12A and 12B, in the optical system 102, the curvature of the lens surface of the variable-focus lens VL is changed, thereby changing the focal length of the variable-focus lens VL and performing focusing from infinity to close-up photography.

[0115] If the image capture unit 104 is a 1 / 4.4-inch sensor, a lens extension amount of 1.5 mm is required when focusing to a close-up shooting distance of 1 m using the full-lens extension method. In contrast, when focusing to a close-up shooting distance of 1 m is performed by changing the focal length of the variable-focus lens VL, extension of the optical system 102 is not required.

[0116] When the optical system 102 has the lens data shown in Table 5, the sum Σ(1 / fi × 1 / νi) of the products of the reciprocal of the lens focal length fi and the reciprocal of the lens Abbe number νi for all lenses other than the variable-focus lens VL takes a negative value. This allows for good correction of chromatic aberration in the optical system 102.

[0117] As shown in FIGS. 13A and 13B, in the optical system 102, a second lens group G2 is disposed after the variable-focus lens VL. By rotating the second lens group G2 about a rotation axis, the image of the object formed on the imaging plane 104a of the imaging unit 104 is moved in a direction perpendicular to the optical axis of the optical system 102, thereby performing OIS. When the optical system 102 has the lens data shown in Table 5, as shown in FIGS. 13A and 13B, when the rotation angle of the second lens group G2 is 5.1 degrees, the movement amount of the image of the object formed on the imaging plane 104a is 0.15 mm. The movement amount of the image of the object formed on the imaging plane 104a is roughly proportional to the tangent of the rotation angle of the second lens group G2. This can be easily understood by considering the properties of trigonometric functions.

[0118] The present disclosure is not limited to the above-described embodiments, and may be replaced with a configuration that is substantially the same as the configuration shown in the above-described embodiments, a configuration that has the same effect, or a configuration that can achieve the same purpose. [Explanation of symbols]

[0119] 1 camera module 101 Reflective element 102 Optical system 103 Infrared cut filter 104 Imaging unit 104a Image plane 105 Case 111 1st optical axis 112 2nd optical axis 121 detector 122 Drive unit 123 Controller G1 First lens group G2 Second lens group St aperture stop VL Variable Focus Lens L1 First lens L1a Object side lens surface L2 Second lens L3 Third lens L4 4th lens

Claims

1. An optical system comprising: a first lens group including two or more lenses, having a positive power as a whole, and transmitting object light; a variable-focus lens having variable power, changing the variable power to focus on a close-distance object that is closer than infinity, and disposed after the first lens group, through which the object light passes; a second lens group including at least one lens, having a negative power as a whole, and disposed after the variable-focus lens to focus the object light onto an imaging unit; Equipped with f: effective focal length of the optical system, fv: the focal length of the variable-focus lens when the focusing is performed, ih: maximum image height of the optical system, TTL: the distance from the object-side lens surface of the lens arranged closest to the object side among the lenses included in the first lens group to the image plane, Fno: F-number of the optical system, d: the distance from the optical system to the close-distance object when the focusing is performed, fi: focal length of the i-th lens from the object side among the lenses other than the variable-focus lens included in the optical system, νi: Abbe number of the i-th lens from the object side among the lenses other than the variable-focus lens included in the optical system, Σ: a symbol indicating that the sum of all lenses included in the optical system other than the variable-focus lens is to be calculated. In this case, 5.0<f×fv / d, ih / f<0.44, 0.7<TTL / f<1.1, 2.0<Fno<6.0 and Σ(1 / fi×1 / νi)<0 An optical system that satisfies the above.

2. A driving device for rotating the second lens group around a rotation axis to perform optical image stabilization. The optical system of claim 1 , comprising:

3. A driving device for optically correcting an image shake by moving the second lens group in a direction perpendicular to the optical axis of the second lens group. The optical system of claim 1 , comprising:

4. The variable focus lens is a liquid lens.

4. The optical system according to claim 1.

5. An optical system according to any one of claims 1 to 3; the imaging unit; Equipped with The imaging unit photoelectrically converts the object light. Camera module.

6. a reflecting element disposed in front of the first lens group, which reflects a first object light beam traveling along a first optical axis to generate a second object light beam traveling along a second optical axis; The object beam is the second object beam. The camera module according to claim 5 .

Images