Optical system and camera module

Abstract

A camera module, disclosed in one embodiment of the present invention, comprises: a first lens group having negative (-) power; second and third lens groups arranged on a sensor side of the first lens group; and a fourth lens group arranged on the sensor side of the third lens group and having negative (-) power, wherein the second and third lens groups carry out zoom magnification from a wide mode to a tele mode by moving along an optical axis of the lenses in the first to fourth lens groups, the number of lenses in at least one of the second and third lens groups is greater than the number of lenses in the fourth lens group, the optical axis distance of the second lens group is greater than the optical axis distance of the first lens group, and the fourth lens group may include a lens having the greatest effective length among the effective lengths of the lenses in the first to fourth lens groups.

Description

Optical system and camera module

[0001] The present invention relates to an optical system for improved optical performance and a camera module including the same.

[0002] Camera modules perform the function of capturing objects and storing them as images or videos, and are installed in various applications. In particular, camera modules are manufactured in an ultra-small size and are applied to portable devices such as smartphones, tablet PCs, and laptops, as well as drones and vehicles, providing various functions. For example, the optical system of a camera module may include an imaging lens that forms an image and an image sensor that converts the formed image into an electrical signal. At this time, the camera module can perform an autofocus (AF) function that automatically adjusts the distance between the image sensor and the imaging lens to align the focal length of the lens, and can perform a zooming function that increases or decreases the magnification of a distant object through a zoom lens. In addition, the camera module adopts image stabilization (IS) technology to compensate for or prevent shaking of the image caused by camera movement due to an unstable fixed device or the user's movements.

[0003] The most important element for a camera module to obtain an image is the imaging lens that forms the image. Recently, interest in high resolution has been increasing, and research is being conducted on optical systems that include multiple lenses to achieve this. For example, research is being conducted using multiple imaging lenses with positive (+) or negative (-) power to achieve high resolution. However, when multiple lenses are included, there is a problem in that it is difficult to derive excellent optical and aberration characteristics. In addition, when multiple lenses are included, the overall length, height, etc. may increase due to the thickness, spacing, size, etc. of the multiple lenses, which increases the overall size of the module that includes the multiple lenses.

[0004] To achieve high-resolution and high-quality images, image sensors are increasing in size. However, as image sensors increase in size, the total track length (TTL) of optical systems containing multiple lenses also increases, leading to an increase in the thickness of cameras, mobile devices, and other devices containing the optical systems.

[0005] When the optical system includes a plurality of lenses, the position of at least one lens or a lens group including at least one lens can be controlled to perform functions such as zoom and autofocus (AF). However, when the lens or the lens group performs the function, the amount of movement of the lens or the lens group can increase exponentially. Accordingly, the optical system has a problem in that a lot of energy may be required to move the lens or the lens group, and a large volume is required considering the amount of movement. In addition, there is a problem in that aberration characteristics are deteriorated due to the movement of the lens or the lens group. Accordingly, there is a problem in that optical characteristics are deteriorated at a certain magnification when performing the zoom and autofocus (AF) functions. Therefore, a new optical system that can solve the above-described problems is required.

[0006] The present invention provides an optical system with improved optical characteristics. The present invention provides an optical system and camera module capable of photographing at various magnifications. The present invention provides an optical system and camera module with improved aberration characteristics at various magnifications. The present invention provides an optical system and camera module that can be implemented in a small and compact form.

[0007] A camera module according to an embodiment of the invention comprises a first lens group adjacent to an object and having negative power; a second lens group disposed on a sensor side of the first lens group; a third lens group disposed on a sensor side of the second lens group; and a fourth lens group disposed on the sensor side of the third lens group and having negative power, wherein the second and third lens groups move along optical axes of lenses in the first to fourth lens groups to perform a zoom magnification from a wide mode to a tele mode, and the number of lenses in at least one of the second and third lens groups is greater than the number of lenses in the fourth lens group, an optical axis distance of the second lens group is greater than an optical axis distance of the first lens group, and the fourth lens group may include a lens having a largest effective length among effective lengths of lenses in the first to fourth lens groups.

[0008] According to an embodiment of the invention, the maximum movement distance of the second or third lens group according to the zoom magnification is Max_mMd13, and can satisfy the mathematical expression: 1 mm < Max_mMd13 < 7 mm. The minimum optical axis distance between the first lens group and the second lens group according to the tele mode is Md3_DG12, and can satisfy the mathematical expression: 0.5 mm ≤ Md3_DG12 < 1.5 mm.

[0009] According to an embodiment of the invention, the lens closest to the object in the first lens group may have positive power and a convex meniscus shape toward the object.

[0010] In the seventh lens group, the lens closest to the image sensor may have positive power and a biconvex shape. The lens closest to the image sensor may be the lens with the largest effective length among the first to fourth lens groups. The seventh lens may be made of glass. The first lens may have a spherical shape and be made of glass.

[0011] According to an embodiment of the invention, the number of lenses of the first lens group is the same as the number of lenses of the second and third lens groups, and each of the first to third lens groups may include lenses having powers of opposite signs. The first lens group may include a reflective member arranged on the object side, and the lens closest to the image sensor may have a shape in which effective lengths in the first and second directions perpendicular to the optical axis are different.

[0012] A camera module according to an embodiment of the invention comprises: a first lens group having first and second lenses sequentially arranged toward an image sensor on an object side, the first lens group having negative power; a second lens group arranged on a sensor side of the first lens group; a third lens group arranged on a sensor side of the second lens group; And a fourth lens group having a last lens disposed between the third lens group and the image sensor, and having a positive power, wherein the second and third lens groups move along the optical axes of the lenses in the first to fourth lens groups to perform a zoom magnification from a wide mode to a tele mode, and the first lens has an object-side surface having a convex shape on the optical axis, and an absolute value of a radius of curvature of a sensor-side surface of the first lens is larger than a radius of curvature of an object-side surface of the first lens, and the first and fourth lens groups are fixed in position on the optical axis, and the number of lenses in the second and third lens groups is smaller than the number of lenses in the fourth lens group, and among the optical axis distances of the first to fourth lens groups, the optical axis distance of the second lens group is the largest, and the optical axis distance of the first to fourth lens groups is a distance in the optical axis direction from an object-side lens to a sensor-side lens disposed in each lens group, and the effective length of the first lens is smaller than the effective length of the last lens, and It may be greater than the effective length of the lenses.

[0013] According to an embodiment of the invention, the refractive index of the first lens is Nd1, the Abbe number is Vd1, the refractive index of the last lens is Ndn, the Abbe number is Vdn, and the mathematical formulas: Nd1*Vd1 < 50, Ndn*Vdn < 50 may be satisfied. The first lens may include a reflective member arranged on the object side, and at least one of the first lens and the last lens may have shapes in which effective lengths in first and second directions perpendicular to the optical axis are different. The second lens group may include a third lens and a fourth lens having powers of opposite signs, the third lens group may include a fifth lens and a sixth lens having powers of opposite signs, and the fourth lens group may include a seventh lens. The first lens may have a meniscus shape convex toward the object on the optical axis, the second lens may have a concave shape on both sides on the optical axis, the object-side lens of the second lens group may have a convex shape on both sides, and the seventh lens may have a convex shape on both sides on the optical axis.

[0014] According to an embodiment of the invention, the total focal length in the wide mode is FMd1, the total focal length in the tele mode is FMd3, and half of the diagonal length of the image sensor is ImgH, and the mathematical expressions: 2 < FMd1 / ImgH < 6, 6 < FMd3 / ImgH < 12 can be satisfied. An aperture arranged on the periphery between the first and second lens groups is included, and an optical axis distance from the aperture to the surface of the image sensor in the wide mode is SD1, and an optical axis distance from the object-side surface of the first lens to the surface of the image sensor is TTL, and the mathematical expression: 0.5 < SD1 / TTL < 1 can be satisfied. An F number of the optical system in the tele mode is Md3_Fno, and the condition: Md3_Fno ≤ 5 can be satisfied.

[0015] The effective length of the lenses arranged in the second and third lens groups may be smaller than the diagonal length of the image sensor.

[0016] A camera module according to an embodiment of the invention comprises: a reflective member that reflects a second optical axis of incident light to a first optical axis; a first lens group disposed on an output side of the reflective member and having negative (-) power; a second lens group disposed on a sensor side of the first lens group and having positive (+) power; a third lens group disposed on a sensor side of the second lens group and having negative (-) power; a fourth lens group disposed on a sensor side of the third lens group and having negative (+) power; a first driving member that moves the second lens group along the first optical axis; And a second driving member for moving the third lens group along the first optical axis, wherein the second and third lens groups move along the first optical axes of the lenses in the first to fourth lens groups to perform a zoom magnification from a wide mode to a tele mode, and the total number of lenses in the first to fourth lens groups is 6 or more, the refractive index of the first lens closest to the object and the n-th lens closest to the image sensor is greater than 1.6, and the n-th lens has the largest effective length among the lenses in the first to fourth lens groups, and the maximum moving distance of the second lens group according to the zoom magnification is Max_mLG2, and the maximum moving distance of the third lens group according to the zoom magnification is Max_mLG3, and the optical axis distance from the object-side first lens of the first lens group to the surface of the image sensor is TTL, and 1 / 2 of the diagonal length of the image sensor is ImgH, and mathematical expression: 5 < TTL / Max_mLG2 < 5.6, 5.2 < TTL / Max_mLG3 < 5.8, 5 < TTL / ImgH < 12 can be satisfied.

[0017] An optical system and a camera module according to an embodiment can have various magnifications and can have excellent optical characteristics when providing various magnifications. Specifically, the embodiment can have various magnifications by controlling the movement distance of each moving lens group and can provide an autofocus (AF) function for a subject. The optical system and camera module according to an embodiment can have multiple lens groups correct aberration characteristics or mutually complement aberration characteristics that change due to movement. Accordingly, the optical system according to the embodiment can minimize or prevent changes in chromatic aberration and aberration characteristics that occur when the magnification changes.

[0018] An optical system and a camera module according to an embodiment can control an effective focal length (EFL) by moving only some lens groups among a plurality of lens groups, and can minimize a moving distance of the moving lens group. Accordingly, the optical system can reduce a moving distance of the moving lens group according to a change in the operation mode, and can minimize power consumption required when the lens group is moved. In the optical system, at least one lens included in a fixed group and a moving group can have a non-circular shape. Accordingly, the optical system can reduce the height of the optical system while maintaining optical performance, and can secure a space for structurally arranging lens groups arranged between the plurality of lens groups.

[0019] The optical system and camera module according to the embodiment can adjust magnification by moving a lens group other than the first lens group adjacent to the subject among the plurality of lens groups. Accordingly, the optical system can maintain a constant TTL value even when the lens group moves according to the change in magnification. Accordingly, the optical system and the camera module including the optical system can be provided with a slimmer structure.

[0020] FIG. 1 is a configuration diagram of an optical system and a camera module having the same according to a first embodiment of the invention.

[0021] Fig. 2 is an example of the operation of the first mode of the optical system of Fig. 1.

[0022] Figure 3 is an example of the operation of the third mode in the optical system of Figures 1 and 2.

[0023] Figure 4 is a table of lens data of an optical system according to a first embodiment of the invention.

[0024] FIG. 5 is a table showing aspherical coefficients of lenses of an optical system according to a first embodiment of the invention.

[0025] FIG. 6 is a graph of diffraction MTF in an optical system of wide, mid, and tele modes according to a first embodiment of the invention.

[0026] Fig. 7 is a graph showing the aberration characteristics in the optical system of the first mode of Fig. 2.

[0027] Fig. 8 is a graph showing the aberration characteristics in the optical system of the second mode (Mid mode) of Fig. 1.

[0028] Fig. 9 is a graph showing the aberration characteristics in the optical system of the third mode (tele mode) of Fig. 3.

[0029] Fig. 10 is a configuration diagram of an optical system and a camera module having the same according to a second embodiment of the invention.

[0030] Fig. 11 is an example of the operation of the first mode of the optical system of Fig. 10.

[0031] Fig. 12 is an example of operation of the third mode in the optical system of Figs. 10 and 11.

[0032] Fig. 13 is a table of lens data of an optical system according to a second embodiment of the invention.

[0033] Fig. 14 is a table showing aspherical coefficients of lenses of an optical system according to a second embodiment of the invention.

[0034] FIG. 15 is a graph of diffraction MTF in an optical system of wide, mid, and tele modes according to a second embodiment of the invention.

[0035] Fig. 16 is a graph showing the aberration characteristics in the optical system of the first mode of Fig. 11.

[0036] Fig. 17 is a graph showing the aberration characteristics in the optical system of the second mode (Mid mode) of Fig. 10.

[0037] Fig. 18 is a graph showing the aberration characteristics in the optical system of the third mode (tele mode) of Fig. 12.

[0038] FIG. 19 is a configuration diagram of an optical system and a camera module having the same according to a third embodiment of the invention.

[0039] Fig. 20 is an example of a change in the first mode of the optical system of Fig. 19.

[0040] Fig. 21 is an example of a change in the third mode in the optical system of Figs. 19 and 20.

[0041] Fig. 22 is a table of lens data of an optical system according to a third embodiment of the invention.

[0042] Fig. 23 is a table showing aspherical coefficients of lenses of an optical system according to a third embodiment of the invention.

[0043] FIG. 24 is a graph of diffraction MTF in an optical system of wide, mid, and tele modes according to a third embodiment of the invention.

[0044] Fig. 25 is a graph showing the aberration characteristics in the optical system of the first mode of Fig. 20.

[0045] Fig. 26 is a graph showing the aberration characteristics in the optical system of the second mode (Mid mode) of Fig. 19.

[0046] Fig. 27 is a graph showing the aberration characteristics in the optical system of the third mode (tele mode) of Fig. 21.

[0047] FIG. 28 is a plan view showing an example of a lens having a cut shape in an optical system according to the first to third embodiments of the invention.

[0048] FIG. 29 is an example of a side cross-sectional view of an optical system and a camera module having a reflective member in the first, second, and third embodiments of the invention.

[0049] FIG. 30 is a drawing showing a camera module according to embodiments of the invention applied to a mobile terminal.

[0050] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. However, the technical idea of ​​the present invention is not limited to some of the embodiments described, but can be implemented in various different forms, and one or more of the components between the embodiments can be selectively combined or substituted within the scope of the technical idea of ​​the present invention. In addition, terms (including technical and scientific terms) used in the embodiments of the present invention can be interpreted as having a meaning that can be generally understood by a person having ordinary skill in the technical field to which the present invention pertains, unless explicitly and specifically defined and described, and terms commonly used, such as terms defined in a dictionary, can be interpreted in consideration of the contextual meaning of the related technology. The terminology used in the embodiments of the present invention is for the purpose of describing the embodiments and is not intended to limit the present invention.

[0051] In this specification, the singular may also include the plural unless specifically stated in the phrase, and when it is described as “A and (or at least one (or more) of B, C,” it may include one or more of all combinations that can be combined with A, B, and C. In addition, when describing components of embodiments of the present invention, terms such as first, second, A, B, (a), (b), etc. may be used. These terms are only for distinguishing the components from other components, and are not limited by the nature, order, or sequence of the components. In addition, when it is described that a component is “connected,” “coupled,” or “connected” to another component, it may include not only cases where the component is directly connected, coupled, or connected to the other component, but also cases where the component is “connected,” “coupled,” or “connected” by another component between the component and the other component. When it is described in the specification that each component is formed or arranged "above or below", above or below includes not only cases where the two components are in direct contact with each other, but also cases where one or more other components are formed or arranged between the two components. In addition, when expressed as "above or below", it can include the meaning of the downward direction as well as the upward direction based on one component.

[0052] In the specification, the convexity of the lens surface may mean that the lens surface in the area corresponding to the optical axis or the paraxial area has a convex shape based on the optical axis, and the concaveness of the lens surface may mean that the lens surface in the area corresponding to the optical axis or the paraxial area has a concave shape. In addition, the "object-side surface" may mean the surface of the lens facing the object side based on the optical axis, and the "sensor-side surface" may mean the surface of the lens facing the imaging surface (image sensor) based on the optical axis. In addition, the center thickness of the lens may mean the thickness of the lens in the optical axis direction. In addition, the vertical direction may mean the direction perpendicular to the optical axis, and the end of the lens or lens surface may mean the end of the effective area of ​​the lens through which incident light passes. In addition, the size of the effective diameter of the lens surface may have a measurement error of up to ±0.4 mm depending on the measurement method, etc.

[0053] As shown in FIGS. 1, 10, and 19, an optical system (1000) according to an embodiment of the invention may include a plurality of lens groups. The plurality of lens groups may include at least three lens groups. The plurality of lens groups include first to fourth lens groups (LG1 to LG4). Each of the plurality of lens groups includes at least one lens. The first to fourth lens groups (LG1 to LG4) may be sequentially arranged along the optical axis (OA) from an object toward the image sensor (300). The optical system (1000) may include n lenses, the n-th lens may be the last lens, and the (n-1)-th lens may be the lens closest to the last lens. The n is an integer greater than or equal to 6, for example, 6 to 9. Within the optical system (1000), the lenses may be defined as lens units (100, 100A, 100B).

[0054] Among the plurality of lens groups, at least two lens groups may be fixed groups having fixed positions, and at least two lens groups may be variable groups having variable positions. For example, a first lens group (LG1) adjacent to an object and a fourth lens group (LG4) adjacent to an image sensor (300) may be fixed groups, and at least one lens group (LG2, LG3) between the first and fourth lens groups (LG1, LG4) may be a variable group having variable positions. Here, the variable group may be reciprocally moved in the optical axis direction. By the movable lens group, the optical system (1000) may provide a continuous zoom optical system having a wide mode, a middle mode, and a tele mode. The second lens group (LG2) is arranged between the first lens group (LG1) and the third lens group (LG3) and may be moved for a zoom magnification. The third lens group (LG3) is arranged between the second lens group (LG2) and the third lens group (LG3) and can be moved for focusing. The moving distance of the moving lens groups can be set to be less than 7 mm at the most, thereby reducing power consumption of the driving unit. In addition, in the tele mode, the optical axis distance (DG12) between the first and second lens groups (LG1, LG2) can be set to be 0.5 mm or more, for example, 0.8 mm or more, thereby reducing the moving distance of the second and third lens groups (LG2, LG3) and providing a high-magnification optical system.

[0055]

[0056] The number of lenses of each of the first lens group (LG1) and the second lens group (LG2) may be the same as or different from each other. For example, the number of lenses of the first lens group (LG1) may be the same as or different from the number of lenses of the second lens group (LG2). The number of lenses of each of the second lens group (LG2) and the third lens group (LG3) may be the same as or different from each other, and may be, for example, two or less. For example, the number of lenses of the third lens group (LG3) may be the same as the number of lenses of the second lens group (LG2). The number of lenses of the fourth lens group (LG4) may be less than the number of lenses of each of the second lens group (LG2) and the third lens group (LG3), and may be, for example, one. The number of lenses of the first lens group (LG1) may be twice or more than the number of lenses of the fourth lens group (LG4). By stacking these lens elements, it is possible to provide optical systems in wide mode, middle mode, and tele mode, and also to provide bright optical systems with F numbers ranging from 2.2 to 5 depending on the operating mode.

[0057] At least one or all of the lenses of the first to fourth lens groups (LG1-LG4) may be made of plastic. In addition, the lenses in the movable lens groups (LG2, LG3) may be arranged of plastic to prevent an increase in power consumption of the driving member. As another example, each of the movable lens groups (LG2, LG3) may include a plastic lens and a glass lens. As another example, the lens closest to the object among the lenses of the fixed lens group (LG1) may be made of glass. As another example, the lens in the lens group closest to the image sensor may be made of glass. At least one or all of the lens surfaces of the lenses of the first to fourth lens groups (LG1-LG4) may have an aspherical shape on the optical axis, or the lens surfaces of at least one lens may have a spherical shape. The lenses having the above-described aspherical surface can prevent spherical aberration within the optical system (1000), and since aberration does not occur even when the effective diameter is increased, miniaturization and weight reduction of the camera module can be possible. The above-described aspherical lens may be made of a glass mold or plastic material. The above-described spherical lens may be made of a glass material.

[0058]

[0059] The power of the first lens group (LG1) may have a sign opposite to that of the power of the second lens group (LG2). The power of the first lens group (LG1) may be negative, and the power of the second lens group (LG2) may be positive. The power of the third lens group (LG3) may have a sign opposite to that of the power of the fourth lens group (LG4). The power of the third lens group (LG3) may be negative, and the power of the fourth lens group (LG4) may be positive. Among the lenses in the optical system (10000), the number of lenses having positive power may be greater than the number of lenses having negative power.

[0060] The focal length of the first lens group (LG1) is FLG1, the focal length of the second lens group (LG2) is FLG2, and the condition of FLG2 < │FLG1│ can be satisfied. The focal length of the third lens group (LG3) is FLG3, and the focal length of the fourth lens group (LG4) is FLG4, and the condition of │FLG3│ < FLG4 can be satisfied. The absolute values ​​of the focal lengths of the first and fourth lens groups (LG1, LG4) whose positions are fixed can be greater than the absolute values ​​of the focal lengths of the second and third lens groups (LG2, LG3). Here, FLG1, FLG3 < 0, and FLG2, FLG4 > 0 can be satisfied. The optical system (1000) can adjust the angle of view (FOV) by the power of each of the first to fourth lens groups (LG1-LG4).

[0061] In the first lens group (LG1), the first lens (101, 111, 121) closest to the object and the second lens (102, 112, 122) closest to the second lens group (LG2) may have refractive powers with opposite signs. Accordingly, the first lens group (LG1) may mutually compensate for chromatic aberrations caused by the plurality of lenses included in the first lens group (LG1). For example, the first lens (101, 111, 121) may have positive power, and the second lens (102, 112, 122) may have negative power. Here, the Abbe number (LG1_Vd3) of the last lens of the first lens group (LG1) may satisfy the following condition: LG1_Vd2 < 35, for example, 20 < LG1_Vd2 < 35. Under these conditions, the first lens group (LG1) can disperse the incident light to the periphery of the second lens group (LG2). In addition, the sensor-side surface (S4) of the lens closest to the second lens group (LG2) within the first lens group (LG1) can have a concave shape on the optical axis. Accordingly, the concave sensor-side surface (S4) of the first lens group (LG1) can refract the light toward the moving second lens group (LG2), thereby reducing the loss of light traveling to the second lens group (LG2) in the area between the first and second lens groups (LG1, LG2).

[0062] The Abbe number (LG2_Vd1) of a lens close to the first lens group (LG1) within the second lens group (LG2) may satisfy the following condition: 35 < LG2_Vd1, for example, 35 < LG2_Vd1 < 65. By this condition, the second lens group (LG2) may refract incident light in the direction of the optical axis of the third lens group (LG3). At least two lenses within the second lens group (LG2) may have powers of opposite signs. Accordingly, the second lens group (LG2) may mutually compensate for chromatic aberrations caused by a plurality of lenses included in the second lens group (LG2). When the Abbe numbers of at least two lenses in the second lens group (LG2) are LG2_Vd1 and LG2_Vd2, the condition: │LG2_Vd1-LG2_Vd2│ > 20 can be satisfied, and when the condition is satisfied, the change in chromatic aberration due to magnification adjustment (Zooming) can be minimized.

[0063] At least two lenses in the third lens group (LG3) can have powers of the same sign. When the Abbe numbers of at least two lenses in the third lens group (LG3) are LG3_Vd1 and LG3_Vd2, the condition: │LG3_Vd1 - LG3_Vd2│ > 20 can be satisfied, and when the condition is satisfied, the change in chromatic aberration due to aberration correction can be minimized. In addition, the power of the third lens group (LG3) can have a negative value, thereby controlling the influence on the focusing direction. Each of the first to fourth lens groups (LG1-LG4) can have at least one lens with positive power, thereby reducing the influence of aberration.

[0064]

[0065] The refractive index (LG4_Nd) of the lenses in the fourth lens group (LG4) can satisfy the following condition: 1.6 < LG4_Nd1, for example, 1.6 < LG4_Nd1 < 1.8. According to this condition, the lenses of the fourth lens group (LG4) can refract incident light toward the center and periphery of the image sensor (300). The fourth lens group (LG4) can play a role of controlling the chief ray angle (CRA). In detail, the optical system (1000) according to the embodiment can have a CRA of less than about 20 degrees, and can correct the chief ray angle (CRA) of light incident on the image sensor (300) to be close to 0 degrees. When the sum of the refractive indices of the lenses in the above optical system (1000) is ∑Nd and the sum of the Abbe numbers is ∑Vd, the following conditions can be satisfied.

[0066] Condition 1: 8 < ∑Nd < 12

[0067] Condition 2: 200 < ∑Vd < 260

[0068] By adjusting the refractive index and Abbe number of the lenses in the optical system (1000), aberration can be controlled. Among the lenses of the optical system (1000), lenses having the maximum Abbe number can be positioned in the second and third lens groups (LG2, LG3). Among the lenses of the optical system (1000), the average refractive index of the lenses of the first and fourth lens groups (LG1, LG4) can be greater than 1.6, and the average refractive index of the lenses of the second and third lens groups (LG2, LG3) can be less than or equal to 1.6. The lens having the maximum Abbe number can reduce chromatic dispersion, and the lens having a refractive index greater than 1.6 can increase chromatic dispersion of incident light.

[0069] Each of the lenses of the optical system (1000) may include an effective area and an ineffective area. The effective area may be an area through which light incident on each of the lenses passes. That is, the effective area may be defined as an effective area or effective diameter through which the incident light is refracted to implement optical characteristics. The ineffective area may be arranged around the periphery of the effective area. The ineffective area may be an area through which effective light is not incident from the plurality of lenses. That is, the ineffective area may be an area unrelated to the optical characteristics. In addition, an end of the ineffective area may be an area fixed to a lens barrel (not shown) that accommodates the lens.

[0070]

[0071] The average effective length of the object-side surface and the sensor-side surface of each lens of the lens unit (100, 100A, 100B) may be provided as 7 mm or less, for example, in the range of 4 mm to 7 mm. Here, the average effective length may be the average of the effective lengths of the object-side surface and the sensor-side surface of each lens. Here, the effective length may be the maximum length when the object-side surface and the sensor-side surface have different lengths in the first and second directions perpendicular to the optical axis. The lens having the largest effective length within the lens unit (100, 100A, 100B) may be the last lens. For example, the effective length of the last lens (106, 116, 126) may be greater than the effective length of the first lens (101, 111, 121). The maximum effective length of the object-side surface (S1) of the first lens (101, 111, 121) may be smaller than the maximum effective length of the sensor-side surface (S6) of the last lens (103, 113, 123). In addition, the first lens (101, 111, 121) may be provided to be larger than the effective lengths of the other lenses except for the last lens, thereby preventing a decrease in the amount of incident light.

[0072] The effective lengths of the first lens closest to the object and the last lens can satisfy the following conditions.

[0073] Condition: 0.75 < CA11 / CAn2 < 0.95

[0074] CA11 is the effective length of the object-side surface of the first lens, and CAn2 is the effective length of the sensor-side surface of the last nth lens. If these conditions are satisfied, the total optical length (TTL: Total Top Length) can be reduced. TTL is the optical axis length from the center of the object-side surface of the first lens (101, 111, 121) to the surface of the image sensor (300).

[0075]

[0076] As shown in Fig. 28, at least one or two or more lenses in the optical system (1000) may have different effective lengths (C1, C2) in the first direction (X) and the second direction (Y) perpendicular to the optical axis (OA). The first and second directions (X, Y) may be perpendicular to each other. The lens (L1) having different effective lengths (C1, C2) in the first and second directions (X, Y) may have a non-circular shape or a D-cut shape, and for example, the effective length (C2) in the first direction (X) may be smaller than the effective length (C1) in the second direction (Y). The first direction (X) may be a direction perpendicular to the thickness direction or the display surface of a device equipped with a camera module, for example, a portable terminal. At least one or both of the object-side and sensor-side surfaces (S21) of the lens (L1) may have a non-circular shape, and the length (C12) of both sides (CS1, CS2) in the first direction (X) may be less than the maximum effective length (C1).

[0077] At least one of the lenses of the first lens group (LG1) may have different effective lengths on the object-side surface and / or the sensor-side surface, and the effective length in the first direction (X) may be less than the effective length in the second direction (Y). At least one of the lenses of the second lens group (LG2) may have different effective lengths on the object-side surface and / or the sensor-side surface, and the effective length in the first direction (X) may be less than the effective length in the second direction (Y). The seventh lens (107, 117, 127) of the fourth lens group (LG4) may have different effective lengths on the object-side surface and / or the sensor-side surface, and the effective length in the first direction (X) may be less than the effective length in the second direction (Y). In detail, among the lenses in the lens unit (100, 100A, 100B), the seventh lens (107, 117, 127) having the largest effective length may have an effective length in the second direction (Y) greater than an effective length in the first direction (X). The first lens (101, 111, 121) may have an effective length in the second direction (Y) greater than an effective length in the first direction (X).

[0078] When the lengths of the first and second directions (X, Y) of the object-side surface (S1) of the m-th lens are different, the maximum effective length in the second direction (Y) is CAm1y, and the minimum effective length in the second direction (X) is CAm1x, then the condition of the formula: 0.55 < CAm1x / CAm1y < 0.98 can be satisfied, and m can be 1.8. When the lengths of the first and second directions (X, Y) of the sensor-side surface (CAm2) of the m-th lens are different, the maximum effective length in the second direction (Y) is CAm2y, and the minimum effective length in the first direction (X) is CAm2x, then the condition of the formula: 0.55 < CAm2x / CAm2y < 0.98 can be satisfied, and m can be 1.8. When the value of the formula in the effective length of the object-side surface or the sensor-side surface of the m-th lens is less than 0.55, it is difficult to manufacture the object-side surface or the sensor-side surface of the m-th lens into a non-circular shape and it is difficult to control the distribution of the incident light, and when it exceeds 0.98, the size reduction in the second direction of the optical system may be minimal. By limiting the maximum effective length of the object-side surface and the sensor-side surface of at least two lenses having the maximum effective length in the first direction (X) to the above range, an increase in the thickness of a mobile terminal equipped with a camera module can be prevented.

[0079] An optical system (1000) according to an embodiment can have improved assembly properties by non-circular lens(es) and a mechanically stable shape. In addition, the optical system (1000) can significantly reduce the moving distance of a moving lens group and provide various magnifications. In addition, since lenses having a large effective length in the second direction (Y) are provided in a shape in which both sides in the second direction (Y) are cut off, the height or thickness of the optical system (1000) and the camera module in the second direction (Y) can be reduced. Accordingly, an increase in the thickness of a device having a slim optical system (1000) and a camera module can be suppressed.

[0080] Within the optical system (1000), the TTL (Total top length) may be more than 4 times the ImgH, and preferably, the condition of 4 < TTL / ImgH < 15 or 6 < TTL / ImgH < 11 may be satisfied. ImgH is half of the maximum diagonal length of the effective area of ​​the image sensor (300). Within the optical system (1000), the effective focal length (EFL) may be more than 10 mm and the diagonal field of view (FOV) may be less than 45 degrees, so as to be provided as a zoom optical system of a portable terminal. Accordingly, the optical system (1000) may provide a high-resolution and high-magnification zoom optical system of three or more lens groups. Within the lens unit (100, 100A, 100B), the number of lenses having an effective length greater than the maximum effective length of the image sensor (300) may be less than 50%, for example, in the range of 10% to 40%. The effective length of the lens closest to the object side within the lens unit (100, 100A, 100B) may be shorter than the effective length of the lens closest to the image sensor (300).

[0081]

[0082] An optical system (1000) according to an embodiment may include an aperture (ST). The aperture (ST) may control the amount of light incident on the optical system (1000). The aperture (ST) may be arranged between any two lenses within the lens unit (100, 100A, 100B). In the lenses arranged between an object and the aperture (ST), the effective diameter of the lenses tends to decrease from the object side toward the aperture (ST). The aperture (ST) may be arranged on the periphery between the first lens group (LG1) and the second lens group (LG2). The effective lengths of the lenses arranged on the object side of the aperture (ST) and the lenses arranged on the sensor side may be smaller than the diagonal length of the image sensor (300). Accordingly, the brightness of the optical system may be controlled. By controlling the effective diameter size of each of the above lenses, the optical system (1000) can control the incident light to compensate for the deterioration of optical characteristics due to resolution and temperature changes, and improve chromatic aberration control characteristics. Here, the effective length of each lens is the average of the effective lengths of the object-side surface and the sensor-side surface in the second direction (Y).

[0083] The above aperture (ST) can be positioned at a set position. The aperture (ST) can be positioned around the object-side surface or the sensor-side surface of one of the lenses of the second lens group (LG2). For example, the aperture (ST) can be positioned around the object-side surface of the second lens group (LG2). As another example, the aperture (ST) can be positioned around the sensor-side surface of the first lens group (LG1). The aperture (ST) can be a portion coated on the surface of at least one selected lens to function as an aperture. In detail, the object-side surface or the sensor-side surface of one lens selected from the lenses of the optical system (1000) can function as an aperture for controlling the amount of light.

[0084] The optical axis distance between the above aperture (ST) and the image sensor (300) is SD, and the value of the SD may vary depending on the operating mode, for example, wide mode, middle mode, and tele mode.

[0085]

[0086] On the optical axis (OA), the first lens group (LG1) and the second lens group (LG2) may have a set interval (DG12). The optical axis interval (DG12) between the first lens group (LG1) and the second lens group (LG2) may be the optical axis interval between the sensor-side surface of the lens closest to the sensor among the lenses in the first lens group (LG1) and the object-side surface of the lens closest to the object among the lenses in the second lens group (LG2). The optical axis interval (DG12) between the first lens group (LG1) and the second lens group (LG2) may be at least 0.5 mm or more. That is, in the tele mode, 0.5 mm ≤ DG12 may be satisfied. Here, among the lens surfaces of the first lens group (LG1) and the second lens group (LG2), two surfaces facing each other may have a concave shape on the sensor side of the first lens group (LG1) and a convex shape on the optical axis (OA). The first lens group (LG1) and the second lens group (LG2) may refract light emitted through the sensor side surface of the first lens group (LG1) to the object side surface of the second lens group (LG2) depending on the operation mode. Alternatively, the sensor side surface of the first lens group (LG1) may have a convex shape on the optical axis (OA) and the object side surface of the second lens group (LG2) may have a concave shape.

[0087] The sum of the center thicknesses of the lenses of the lens units (100, 100A, 100B) of the embodiment is ∑CT and may be 14 mm or less, for example, in the range of 8 mm to 14 mm or in the range of 9 mm to 12 mm. The sum of the center spacings between the lenses on the optical axis (OA) is ∑CG and may be 8 mm or more, for example, in the range of 8 mm to 14 mm, and may be greater than the sum of the center thicknesses of the lenses. For example, the condition: ∑CT < ∑CG may be satisfied. When the center spacings between the lenses are made larger than the center thicknesses of the lenses, the weight of the lenses of the moving group can be reduced, and an increase in power consumption of the driving member can be prevented.

[0088] The optical system (1000) or camera module may include an image sensor (300). The image sensor (300) may detect light and convert it into an electrical signal. The image sensor (300) may detect light that has sequentially passed through the lens units (100, 100A, 100B). The image sensor (300) may include an element capable of detecting incident light, such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor).

[0089]

[0090] The optical system (1000) or camera module may include an optical filter (500). The optical filter (500) may be disposed between the fourth lens group (LG4) and the image sensor (300). The optical filter (500) may be disposed between the lens closest to the sensor side among the lenses of the lens unit (100, 100A, 100B) and the image sensor (300). For example, the optical system (100, 100A, 100B) may be disposed between the last lens and the image sensor (300). A cover glass (not shown) is disposed between the optical filter (500) and the image sensor (300), and may protect the upper portion of the image sensor (192) and prevent a decrease in the reliability of the image sensor (192). The cover glass may be removed. The optical filter (500) may include an infrared filter or an infrared cut-off filter (IR cut-off). The optical filter (500) may allow light of a set wavelength band to pass through and filter out light of a different wavelength band. When the optical filter (500) includes an infrared filter, it may block radiant heat emitted from external light from being transmitted to the image sensor (300). In addition, the optical filter (500) may transmit visible light and reflect infrared light.

[0091] The optical system (1000) according to the embodiment may further include a reflective member (400) for changing the path of light, as illustrated in FIG. 29. The reflective member (400) may be implemented as a prism or reflective mirror that reflects incident light of the first lens group (LG1) toward the lenses. Hereinafter, the optical system according to each embodiment will be described in detail.

[0092]

[0093] <First embodiment>

[0094] FIGS. 1 to 9 are drawings of an optical system according to a first embodiment. Referring to FIGS. 1 to 5, an optical system (1000) according to the first embodiment may include a plurality of lens groups, for example, first to fourth lens groups (LG1, LG2, LG3, LG4). The first to fourth lens groups (LG1, LG2, LG3, LG4) may include lens groups having fixed positions and movable lens groups. The first lens group (LG1) and the fourth lens group (LG4) are lens groups having fixed positions, and the second lens group (LG2) and the third lens group (LG3) are lens groups having variable positions. The second lens group (LG2) is arranged between the first lens group (LG1) and the third lens group (LG3), and the third lens group (LG3) can be arranged between the second lens group (LG2) and the fourth lens group (LG4). The first lens group (LG1) refracts incident light toward the second lens group (LG2), the second lens group (LG2) moves along the optical axis (OA) and changes the zoom magnification (focal length), and the third lens group (LG3) moves along the optical axis (OA) and can adjust the focus position on the image surface of the image sensor (300).

[0095] The absolute value of the focal length of the first lens group (LG1) may be greater than the absolute value of the focal lengths of the second and third lens groups (LG2, LG3). For example, the absolute value of the focal length of the first lens group (LG1) may be more than twice the focal length of the second lens group (LG2). Accordingly, the first lens group (LG1) may disperse the incident light. The difference in focal length between the second lens group (LG2) and the third lens group (LG3) may be 5 mm or less. The focal length of the fourth lens group (LG4) may be less than the absolute value of the focal length of the first lens group (LG1) and greater than the absolute value of the focal length of the third lens group (LG3). The power of the first and third lens groups (LG1, LG3) may have negative power, and the power of the second and fourth lenses (LG2, LG4) may have positive power.

[0096]

[0097] The lens unit (100) may include the first to seventh lenses (101-107). The first to seventh lenses (101-107) and the image sensor (300) may be sequentially arranged along the optical axis (OA) of the optical system (1000). The number of lenses in the first lens group (LG1) may include at least two lenses for adjusting the amount of incident light, power, and chromatic aberration, and may include, for example, the first and second lenses (101, 102). The second lens group (LG2) may include two or fewer lenses and include the third and fourth lenses (103, 104), the third lens group (LG3) may include the fifth and sixth lenses (105, 106), and the fourth lens group (LG4) may include the seventh lens (107). When the focal lengths of the first to fourth lens groups (LG1-LG4) are defined as FLG1, FLG2, FLG3, and FLG4, the following conditions can be satisfied.

[0098] Condition 1: FLG2*2 ≤ │FLG1│ < FLG2*5

[0099] Condition 2: FLG2 -│FLG3│ < FLG4 - FLG2

[0100] Condition 3: FLG4 < │FLG1│

[0101] Condition 4: FLG4 < (│FLG3│ + FLG2) < │FLG1│

[0102] Since the first lens group (LG1) is fixed in position, and the second lens group (LG2) and the third lens group (LG3) are movable in the direction of the optical axis (OA), the optical system (1000) can provide various magnifications by moving the lens groups. In addition, the seventh lens (107) of the fourth lens group (LG4) can control the incident angle of the chief ray to refract light parallel to the optical axis so that it is incident toward the image sensor (300).

[0103] The first and second lenses (101, 102) can correct aberrations by having powers of opposite signs (+, -), and the third and fourth lenses (103, 104) can correct aberrations by having powers of opposite signs (+, -). The fifth and sixth lenses (105, 106) can correct aberrations by having powers of opposite signs (+, -). The center spacing between the first and second lenses (101, 102) may be a fixed spacing according to the operation mode described below. For example, the center spacing between the first and second lenses (101, 102) may not change depending on the operation mode and may have a constant spacing. Here, the center spacing between the lenses may mean the optical axis spacing between adjacent lenses.

[0104] The third and fourth lenses (103, 104) may have a set interval. In detail, the center interval between adjacent lenses (104, 105) may be a fixed interval depending on the operation mode to be described later. The fifth and sixth lenses (105, 106) may have a set interval. In detail, the center interval between the fifth and sixth lenses (105, 106) may be constant and not change even if the operation mode to be described later changes. The optical axis interval (BFL) between the seventh lens (107) and the image sensor (300) may be constant and not change depending on the operation mode. The seventh lens (107) has a set interval with the image sensor (300) or / and the optical filter (500), and may have a fixed interval and not change depending on the operation mode.

[0105]

[0106] The first lens (101) may have a positive (+) power on the optical axis (OA). The first lens (101) may include a plastic or glass material, and may be, for example, a plastic material. The first lens (101) may include a first surface (S1) on the object side and a second surface (S2) on the sensor side. The first surface (S1) may have a convex shape on the optical axis (OA), and the second surface (S2) may have a convex shape. That is, the first lens (101) may have a convex shape on both sides on the optical axis (OA). Alternatively, the first lens (101) may have a meniscus shape that is convex toward the object. Alternatively, the first surface (S1) may have a concave shape, and the second surface (S2) may have a convex shape. At least one or both of the first surface (S1) and the second surface (S2) may be aspherical, and the conic constant (K) and the aspherical coefficients (AI) from the 4th to the 20th order of the first and second surfaces (S1, S2) may be represented by L1S1 and L1S2 in FIG. 5.

[0107] The maximum effective length of the first lens (101) may be the second largest among the lenses. That is, the effective length of the first surface (S1) of the first lens (101) in the major axis direction or the second direction (Y) may be greater than the average of the effective lengths of the object-side surfaces and the sensor-side surfaces of the second to sixth lenses (102-106). Accordingly, the first lens (101) may improve optical aberrations or control incident light. The first surface (S1) and the second surface (S2) may be provided without a critical point from the optical axis to the end of the effective area.

[0108] The second lens (102) may have positive (+) or negative (-) power on the optical axis (OA), for example, negative power. The second lens (102) may include a plastic or glass material, for example, a plastic material. The second lens (102) may include a third surface (S3) on the object side and a fourth surface (S4) on the sensor side, and the third surface (S3) on the optical axis may have a concave shape, and the fourth surface (S4) may have a concave shape. The second lens (102) may have a concave shape on both sides. Alternatively, the second lens (102) may have a meniscus shape that is convex toward the object. Alternatively, the third surface (S3) may have a convex shape, and the fourth surface (S4) may have a convex shape. Alternatively, the third surface (S3) may have a concave shape, and the fourth surface (S4) may have a convex shape. At least one or both of the third surface (S3) and the fourth surface (S4) of the second lens (102) may be aspherical, and the conic constant (K) and the aspherical coefficient (AI) may be represented by L2S1 and L2S2 in FIG. 5. The third surface (S3) and the fourth surface (S4) may be provided without a critical point from the optical axis to the end of the effective area.

[0109]

[0110] The third lens (103) may have a power of the same sign as the power of the first lens (101) on the optical axis (OA). That is, the third lens (103) may have a positive power. The third lens (103) may include a plastic or glass material, and may be, for example, a plastic material. The third lens (103) may include a fifth surface (S5) on the object side and a sixth surface (S6) on the sensor side. The fifth surface (S5) may have a convex shape on the optical axis (OA), and the sixth surface (S6) may have a convex shape. The third lens (103) may have a convex shape on both sides. Alternatively, the fifth surface (S5) may have a convex shape, and the sixth surface (S6) may have a concave shape. At least one or both of the fifth surface (S5) and the sixth surface (S6) of the third lens (103) may be aspherical. The conic constant (K) and the aspherical coefficient (AI) of the fifth and sixth surfaces (S5, S6) may be represented by L3S1 and L3S2 in Fig. 5. The fifth surface (S5) and the sixth surface (S6) may be provided without a critical point from the optical axis to the end of the effective area, or the sixth surface (S6) may have a critical point at the edge portion.

[0111]

[0112] The second lens (102) can compensate for chromatic aberration occurring in the first lens (101). The refractive index of the first lens (101) is arranged to be greater than the refractive index of the second lens (102), so as to disperse the incident light. Accordingly, since the first lens group (LG1) controls the dispersion of the light provided to the second lens group (LG2), an increase in the lens size of the second lens group (LG2) can be suppressed. The change in the center distance (DG12) between the first and second lens groups (LG1, LG2) can be set according to the operating mode by the radius of curvature of the fourth surface (S4) of the second lens (102).

[0113] The fourth lens (104) may have a negative (+) power on the optical axis (OA). The fourth lens (104) may include a plastic or glass material, for example, may be a plastic material, and may have a refractive index of less than 1.6. The fourth lens (104) includes a seventh surface (S7) on the object side and an eighth surface (S8) on the sensor side, and the seventh surface (S7) may have a convex shape on the optical axis, and the eighth surface (S8) may have a convex shape. That is, the fourth lens (104) may have a convex shape on both sides on the optical axis (OA). Alternatively, the seventh surface (S7) may be convex on the optical axis (OA), and the eighth surface (S8) may be concave on the optical axis (OA). At least one or both of the seventh surface (S7) and the eighth surface (S8) of the fourth lens (104) may be aspherical. The conic constant (K) and the aspherical coefficient (AI) of the seventh and eighth surfaces (S7, S8) may be represented by L4S1 and L4S2 in Fig. 5. The seventh surface (S7) and the eighth surface (S8) may be provided without critical points from the optical axis to the ends of the effective areas.

[0114] The third lens (103) may have a convex shape on both sides, and the fourth lens (104) may have a concave shape on both sides. The center thickness (CT3) of the third lens (103) may be thicker than the edge thickness. The center thickness of the fourth lens (104) may be thinner than the edge thickness. Accordingly, the gap between the sixth and seventh surfaces (S8, S9) may be reduced by the convex sixth surface (S8) of the third lens (103) and the concave seventh surface (S7) of the fourth lens (104). The Abbe number (Vd3) of the third lens (103) may be greater than the Abbe numbers of the first and second lenses (101, 102) and the fourth and fifth lenses (104, 105). The difference in Abbe numbers between the third lens (103) and the fourth lens (104) may be greater than 20 or greater than 25. Accordingly, the second lens group (LG2) can minimize changes in chromatic aberration caused by changes in position according to changes in the operation mode.

[0115]

[0116] The fifth lens (105) may have a positive (+) or negative (-) power on the optical axis (OA). The fifth lens (105) may have a positive power and a sign opposite to the power of the fourth lens (104). The fifth lens (105) may include a plastic or glass material, and may be, for example, a plastic material. The fifth lens (105) may include a ninth surface (S9) on the object side and a tenth surface (S10) on the sensor side. The ninth surface (S9) may have a concave shape on the optical axis (OA), and the tenth surface (S10) may have a convex shape. That is, the fifth lens (105) may have a meniscus shape that is convex toward the sensor side on the optical axis (OA). Alternatively, the fifth lens (105) may have a concave shape on both sides. In contrast, the fifth lens (105) may have a convex shape toward the object. At least one or both of the ninth surface (S9) and the tenth surface (S10) may be aspherical. The conic constant (K) and the aspherical coefficient (AI) of the ninth and tenth surfaces (S9, S10) may be represented by L5S1 and L5S2 in FIG. 5. The ninth surface (S9) and the tenth surface (S10) of the fifth lens (105) may be provided without a critical point from the optical axis to the end of the effective area.

[0117] The sixth lens (106) may have positive (+) or negative (-) power on the optical axis (OA), for example, may have negative power. The sixth lens (106) may include a plastic or glass material, for example, may be a plastic material. The sixth lens (106) may include an eleventh surface (S11) on the object side and a twelfth surface (S12) on the sensor side. The eleventh surface (S11) may have a concave shape on the optical axis (OA), and the twelfth surface (S12) may have a convex shape. That is, the sixth lens (106) may have a meniscus shape that is convex toward the sensor side on the optical axis (OA). Alternatively, the eleventh surface (S11) may have a convex shape on the optical axis (OA), and the twelfth surface (S12) may have a convex shape on the optical axis (OA). Alternatively, the eleventh surface (S11) may have a concave shape in the optical axis (OA), and the twelfth surface (S12) may have a concave shape in the optical axis (OA). Alternatively, the eleventh surface (S11) may have a convex shape in the optical axis (OA), and the twelfth surface (S12) may have a concave shape in the optical axis (OA). At least one or both of the eleventh surface (S11) and the twelfth surface (S12) of the sixth lens (106) may be aspherical. The aspherical coefficient (AI) and the conic constant (K) of the eleventh and twelfth surfaces (S11, S12) may be represented by L6S1 and L6S2 in FIG. 5. The eleventh surface (S11) and the twelfth surface (S12) may be provided without a critical point from the optical axis to the end of the effective area.

[0118] The seventh lens (107) may have positive (+) or negative (-) power on the optical axis (OA), and may have positive power. The power of the seventh lens (107) has a sign opposite to that of the power of the sixth lens (106), so as to improve chromatic aberration. The seventh lens (107) may include a plastic or glass material, and may be, for example, a plastic material. The seventh lens (107) may include a 13th surface (S13) on the object side and a 14th surface (S14) on the sensor side. The 13th surface (S13) may have a convex shape on the optical axis (OA), and the 14th surface (S14) may have a convex shape. That is, the seventh lens (107) may have a convex shape on both sides on the optical axis (OA). As another example, the 13th surface (S13) may have a concave shape and the 14th surface (S14) may have a convex shape. Alternatively, the 13th surface (S13) may have a concave shape and the 14th surface (S14) may have a concave shape in the optical axis (OA). Alternatively, the 13th surface (S13) may have a convex shape and the 14th surface (S14) may have a concave shape.

[0119] At least one or both of the 13th surface (S13) and the 14th surface (S12) of the seventh lens (107) may be aspherical. The aspherical coefficient (AI) and the conic constant (K) of the 13th and 14th surfaces (S13, S14) may be represented by L7S1 and L7S2 of FIG. 5. The 13th surface (S13) and the 14th surface (S14) may be provided without a critical point from the optical axis to the end of the effective area. As another example, the 13th surface (S13) or / and the 14th surface (S14) of the seventh lens (107) may have a critical point between the optical axis and the end of the effective area, and the critical point is a point where the trend of the Sag value changes. That is, the critical point is a point where the Sag value increases and then decreases on the lens surface, or a point where the Sag value decreases and then increases. The above Sag value is the optical axis distance between the straight line perpendicular to the center of each lens surface and the lens surface, and the Sag value has a positive value at a position located closer to the sensor than the center of each lens surface, and a negative value at a position located closer to the object than the center of each lens surface. The absolute value difference of the radii of curvature between the object-side surface and the sensor-side surface of the third to seventh lenses (103, 104, 105, 106) may be 10 mm or less, for example, 6 mm or less. Since the difference in the radii of curvature between the object-side surface and the sensor-side surface of these movable lenses is not set to be large, the change in the optical path can be predicted, and the increase in the size of the lenses can be suppressed. In addition, since the absolute value difference in the radii of curvature between the object-side surface and the sensor-side surface of the first lens (101) is the largest, the incident light can be dispersed, and since the difference in the radii of curvature between the object-side surface and the sensor-side surface of the last lens (107) is the smallest, the light can be refracted into parallel light across the entire area of ​​the image sensor (300).

[0120]

[0121] The sixth lens (106) and the seventh lens (107) have powers of opposite signs, and the difference in Abbe numbers may be greater than 20, for example, greater than 30, in which case chromatic aberration can be controlled. Accordingly, the third lens group (LG3) can minimize chromatic aberration changes caused by positions that change according to mode changes and perform an achromatic function. The seventh lens (107) can refract incident light parallel to the surface of the image sensor (300) by setting the difference between the absolute value of the radius of curvature of the 13th surface (S13) and the absolute value of the radius of curvature of the 14th surface (S14) to be less than 1.5 mm. The effective length of the seventh lens (107) is provided to be longer than the effective length of the sixth lens (106), so that the incident light can be refracted to the periphery of the image sensor (300).

[0122] At least one of the first lens (101) and the seventh lens (107) may have a non-circular shape in which the effective lengths in the first direction (X) and the second direction (Y) are different from each other. The fourth lens group (LG4) may perform a function of controlling the chief ray angle (CRA). In detail, the CRA of the optical system (1000) according to the embodiment may be less than about 20 degrees, and the seventh lens (107) of the fourth lens group (LG4) may correct the chief ray angle (CRA) of light incident on the image sensor (300) according to each operation mode.

[0123]

[0124] The camera module can move at least one or all of the second and third lens groups (LG2, LG3) among the plurality of lens groups (LG1, LG2, LG3, LG4) included in the optical system (1000) toward the object side or the sensor side along the optical axis (OA). As shown in Fig. 29, the camera module can include a driving member (DM1, DM2) connected to the optical system (1000). The driving members (DM1, DM2) include at least one or a plurality of first driving members (DM1) arranged on the outside of the second lens group (LG2) and at least one or a plurality of second driving members (DM2) arranged on the outside of the third lens group (LG3), and can move each of them in the direction of the optical axis (OA) according to the operation mode. The above operation mode may include a first mode moving at a first magnification as shown in FIG. 2, and a third mode operating at a second magnification different from the first magnification as shown in FIG. 3. At this time, the second magnification may be greater than the first magnification. In addition, the operation mode may include a second mode having a magnification between the first and third modes as shown in FIG. 1. Here, the first magnification may be the lowest magnification of the optical system (1000), and the second magnification may be the highest magnification of the optical system (1000). The first mode may be a wide mode, the second mode may be a middle mode, and the third mode may be a tele mode.

[0125] As shown in Fig. 29, the driving members (DM1, DM2) can move (M1, M2) each of the second and third lens groups (LG2, LG3) or operate them in an initial mode according to one operation mode selected from the first to third modes. In detail, each of the plurality of driving members (DM1, DM2) is connected to the second lens group (LG2) and the third lens group (LG3), and can move each of the second lens group (LG2) and the third lens group (LG3) according to the operation mode. The initial mode may be any one of the first, second, and third modes, for example, the second mode or the middle mode. For example, in the first mode, each of the second lens group (LG2) and the third lens group (LG3) may be positioned at a position defined as a first position (Position 1). In the second mode, each of the second lens group (LG2) and the third lens group (LG3) may be positioned at a second position (Position 2) defined as being closer to the object than the first position. In the third mode, each of the second lens group (LG2) and the third lens group (LG3) may be positioned at a third position (Position 3) defined as being closer to the sensor than the first position. The first position may be an area between the second and third positions.

[0126]

[0127] The first position at which the second lens group (LG2) is positioned in the first mode may be an area between the second and third positions at which the second lens group (LG2) is positioned in the second and third modes. The first position at which the third lens group (LG3) is positioned in the first mode may be an area between the second and third positions at which the third lens group (LG3) is positioned in the second and third modes. Depending on the operation mode, at least one of the second lens group (LG2) and the third lens group (LG3) may move along the optical axis, and the first and fourth lens groups (LG1, LG4) may be arranged at fixed positions. Depending on the operation mode, the second lens group (LG2) may move (M1), and the first and fourth lens groups (LG1, LG4) may be arranged at fixed positions. Depending on the operation mode, the third lens group (LG3) can move (M1), and the first and fourth lens groups (LG1, LG4) can be arranged at fixed positions. In each of the first position, the second position, and the third position according to the operation mode, the first to fourth lens groups (LG1, LG2, LG3, LG4) can have a set interval from the adjacent lens groups. Accordingly, the optical system (1000) can have a constant TTL (Total track length) and BFL according to the operation mode, and the effective focal length and magnification of the optical system (1000) can be controlled by controlling the positions of some lens groups. For convenience of explanation, the center thickness of each of the first to seventh lenses (101-107) is CT1-CT7, the Abbe number is Vd1-Vd7, the refractive index is Nd1-Nd7, and the average of the second direction (Y) or maximum effective length can be defined as CA1-CA7.

[0128]

[0129] The effective length (CA1) of the first lens (101) is the second longest among the lenses, and the effective length (CA5) of the fifth lens (105) is the shortest among the lenses. The effective length (CA1) of the first lens (101) may be 5 mm or more. The effective lengths (CA5, CA6) of the fifth and sixth lenses (105, 106) may be less than 5 mm. The absolute value difference in the radius of curvature between the 13th surface (S13) and the 14th surface (S14) of the seventh lens (107) may be the smallest among the differences in the radius of curvature (absolute value) between the object-side surface and the sensor-side surface of each lens, and may be, for example, 1.5 mm or less or 1 mm or less. The absolute value difference in the radius of curvature between the eleventh surface (S11) and the twelfth surface (S12) of the sixth lens (106) may be 3 mm or less, for example, in the range of 1.5 mm to 3 mm. Since the center thickness (CT6) of the sixth lens (106) is less than 2 mm and the difference in the radius of curvature (absolute value) of both sides is small, light can be guided to the seventh lens (107) without significantly changing the path of the incident light.

[0130] In the absolute value of the focal length, the focal length (F5) of the fifth lens (105) may be the largest among the lenses, and the difference (absolute value) in the focal length between adjacent two lenses may be the largest for the fifth and sixth lenses (105, 106), and the difference (absolute value) in the focal lengths of the second and third lenses (102, 103) may be the smallest. The focal lengths of the first to seventh lenses (101-107) may be defined as F1-F7, and may satisfy the following conditions.

[0131] Condition 1: │F2│ < F1 < │F2│*3

[0132] Condition 2: 0 < (│F2│ - F3) ≤ (│F4│- F3) < 6mm

[0133] Condition 3: │F6│ < F7 < F5

[0134] Condition 4: (│F2│ + F3 + │F4│) < F5

[0135] At least one of the center thicknesses (CT3, CT4, CT5) of the third, fourth, and fifth lenses (103, 104, and 105) may be the thickest among the center thicknesses of the lenses, for example, 2 mm or more, and the center thickness (CT5) of the fifth lens (105) may be the largest. At least one of the center thicknesses (CT2, CT6) of the second and sixth lenses (102, 106) may be the thinnest among the center thicknesses of the lenses, so that the light path can be adjusted according to the positional movement of the second and third lens groups (LG2, LG3). The radius of curvature of the first to fourth surfaces (S1, S2, S3, S4) of the first and second lenses (101, 102) may be set to 5 mm or more, so as not to cause a large change in the refractive angle of the incident light, and can be guided to the fourth lens (104) through the third lens (103).

[0136] The central thicknesses (CT3, CT4) of the third and fourth lenses (103, 104) of the second lens group (LG2) may each be greater than the sum of the central thicknesses (CT1, CT2) of the first and second lenses (101, 102). The sum of the central thicknesses (CT3, CT4) of the third and fourth lenses (103, 104) of the second lens group (LG2) may be greater than the sum of the central thicknesses (CT6, CT7) of the sixth and seventh lenses (106, 107). Accordingly, the second lens group (LG2) can guide light incident through the first lens group (LG1) to the effective area of ​​the third lens group (LG3).

[0137] The optical axis spacing between the first and second lens groups (LG1, LG2) is DG12, the optical axis spacing between the second and third lens groups (LG2, LG3) is DG23, and the optical axis spacing between the third and fourth lens groups (LG3, LG4) is DG34, and each of these may be at least 0.5 mm or more and at most 8 mm or less depending on the magnification change of the operating modes. Specifically, the optical axis spacing (DG12) between the first and second lens groups (LG1, LG2) may be at least 0.5 mm, for example, in the range of 0.5 mm to 7 mm. The optical axis spacing (DG23) between the second and third lens groups (LG2, LG3) may be at least 1 mm, for example, in the range of 1 mm to 3 mm. The optical axis spacing (DG34) between the third and fourth lens groups (LG3, LG4) may be 0.8 mm or more, for example, in the range of 0.8 mm to 8 mm.

[0138] The relationship between DG12, DG23, and DG34 in modes 1, 2, and 3 is as follows.

[0139] Mode 1 (Wide): DG34 < DG23 < DG12

[0140] Second Mode (MID): DG23 < DG12 < DG34

[0141] Mode 3 (Tele): DG12 < DG23 < DG34

[0142] In the first mode, DG12 and DG23, in the second mode, DG12 and DG34, and in the third mode, DG23 and DG34 may be greater than the BFL. Here, the BFL is the optical axis distance from the sensor side of the fourth lens group (LG4) or the seventh lens (107) to the surface of the image sensor (300).

[0143]

[0144] In the above 1st, 2nd, and 3rd modes, the maximum movement distance of the 2nd and 3rd lens groups (LG2, LG3) is Max_mMd13, and can satisfy Max_mMd13 < 5.7mm, and preferably, 4mm < Max_mMd13 ≤ 5.5mm. Accordingly, the maximum movement distance for zoom magnification can be reduced, thereby reducing power consumption of the driving member.

[0145] Depending on the operating mode, the F number of the optical system (1000) provides a brightness of 5 or less, and the F number may be in the range of 2.2 to 5. The aperture may be located between the first lens group (LG1) and the second lens group (LG2), and may be arranged, for example, around the fifth surface (S5) of the third lens (103).

[0146]

[0147] Table 1 and FIG. 4 are for the items of the mathematical formulas described above in the optical system (1000) of the first embodiment, including the TTL (Total track length) (mm), BFL (Back focal length), effective focal length (F) (mm), focal length of each lens group, ImgH (mm), effective length (mm), center thickness (CT) of each lens, center spacing (CG) between two adjacent lenses, TD (mm), which is the optical axis distance from the first surface (S1) to the fourteenth surface (S14), focal lengths (F1, F2, F3, F4, F5, F6, F7) (mm) of each of the first to seventh lenses, diagonal angle of view (FOV) (Degree), F number, etc.

[0148] Item Example 1 Item Example 1 FLG1 (mm) - 24.790 TD (mm) 20.82 FLG2 (mm) 6.850 ImgH (mm) 2.8 FLG3 (mm) - 6.14 TTL (mm) 22.320 FLG4 (mm) 10.770 BFL (mm) 1.500

[0149] Table 2 can represent the effective focal length (F), field of view (FOV), F number, entrance pupil size (EPD), SD, and center spacing between adjacent lens groups (DG12, DG23, DG34) according to the first to third modes in the optical system according to the first embodiment. SD is the optical axis distance from the position of the aperture to the image sensor.

[0150] Example 1 Mode 1 Mode 2 Mode 3 F (mm) 12.65 18.95 25.25 DG 12 (mm) 5.78 03.120 0.930 DL G 23 (mm) 2.000 1.59 01.650 D G 34 (mm) 1.33 04.400 6.530 EPD (EPD1 / EPD2 / EPD3) 4.49 4.96 5.44 Fno (Fno1 / Fno2 / Fno3) 2.800 3.800 4.600 FOV (degrees) 25 17 13 SD 12.54 15.2017.38

[0151]

[0152] As shown in Fig. 6, the optical system according to the first embodiment can have MTF characteristics according to the first, second, and third modes (Wide, Mid, Tele mode). In detail, Fig. 6 is a graph of the diffraction MTF characteristics of the optical system (1000) operating in the first to third modes, and it can be seen that the change in the position of defocusing according to the operating mode is not large.

[0153] FIGS. 7 to 9 are graphs measuring spherical aberration (longitudinal spherical aberration), astigmatic field curves, and distortion from left to right in an aberration graph of an optical system according to the first embodiment. In FIGS. 7 to 9, the X-axis may represent a focal length (mm) and a degree of distortion (%), and the Y-axis may represent the height of the image. In addition, the graph for spherical aberration is a graph for light in wavelength bands of about 435 nm, about 486 nm, about 546 nm, about 587 nm, and about 656 nm, and the graphs for astigmatic aberration and distortion aberration are graphs for light in wavelength bands of 546 nm. In the aberration diagram, it can be interpreted that the closer each curve is to the Y-axis, the better the aberration correction function, and it can be seen that the aberration change according to the operation mode (Wide, Mid, Tele mode) is not large.

[0154]

[0155] <Second embodiment>

[0156] FIGS. 10 to 18 are drawings showing an optical system and a camera module according to a second embodiment. When describing a configuration according to the second embodiment, the same configuration as the first embodiment may include the configuration and description of the first embodiment. Referring to FIGS. 10 to 14, an optical system (1000) according to the second embodiment may include a lens unit (100A) having first to fourth lens groups (LG1, LG2, LG3, LG4). The first lens group (LG1) and the fourth lens group (LG4) are lens groups with fixed positions, and the second lens group (LG2) and the third lens group (LG3) are lens groups with variable positions.

[0157] The absolute value of the focal length of the first lens group (LG1) may be greater than the absolute values ​​of the focal lengths of the second, third, and fourth lens groups (LG2, LG3, and LG4). For example, the absolute value of the focal length of the first lens group (LG1) may be more than twice the focal length of the second lens group (LG2). The focal length of the second lens group (LG2) may be less than the focal length of the fourth lens group (LG4). The focal length of the fourth lens group (LG4) may be greater than the absolute value of the focal length of the third lens group (LG3). The absolute value of the difference in the focal lengths of the second and third lens groups (LG2, LG3) may be 5 mm or less. The first and third lens groups (LG1, LG3) may have negative power on the optical axis, and the second and fourth lens groups (LG2, LG4) may have positive power on the optical axis.

[0158] The lens unit (100A) may include the first to seventh lenses (111-117). The first to seventh lenses (111-117) and the image sensor (300) may be sequentially arranged along the optical axis (OA) of the optical system (1000). The first lens group (LG1) may include the first and second lenses (111, 112). The second lens group (LG2) may include the third and fourth lenses (113, 114), the third lens group (LG3) may include the fifth and sixth lenses (115, 116), and the fourth lens group (LG4) may include the seventh lens (117).

[0159] The focal lengths of the first to fourth lens groups (LG1-LG4) can satisfy the following conditions.

[0160] Condition 1: FLG2*2 ≤ │FLG1│ < FLG2*5

[0161] Condition 2: FLG2 -│FLG3│ < FLG4 - FLG2

[0162] Condition 3: FLG4 < │FLG1│

[0163] Condition 4: FLG4 < (│FLG3│ + FLG2) < │FLG1│

[0164] The first and fourth lens groups (LG1, LG4) are fixed in position, and the second lens group (LG2) and the third lens group (LG3) are movable in the direction of the optical axis (OA), so that the optical system (1000) can provide various magnifications by moving the lens groups. The seventh lens (117) can control the incident angle of the principal ray to refract light parallel to the optical axis so that it is incident toward the image sensor (300).

[0165]

[0166] The first and second lenses (111, 112) can correct aberrations by having powers of opposite signs (+, -), and the third and fourth lenses (113, 114) can correct aberrations by having powers of opposite signs (+, -). The fifth and sixth lenses (115, 116) can correct aberrations by having powers of opposite signs (+, -). The first, second, fifth, and seventh lenses (111, 112, 115, 117) can have positive (+) powers in the optical axis (OA). The second, fourth, and sixth lenses (112, 114, 116) can have negative (-) powers in the optical axis (OA). The materials of the first to sixth lenses (111-116) and the material of the seventh lens (117) may be different from each other. The first to sixth lenses (111-116) may have an aspherical shape, and the seventh lens (117) may have a spherical shape. The material of the first to sixth lenses (111-116) may be a plastic material, and the seventh lens (117) may be a glass material.

[0167] On the optical axis, the first surface (S1) of the first lens (111) may have a convex shape, and the second surface (S2) may have a concave shape. The radius of curvature of the second surface (S2) on the optical axis may be larger than the radius of curvature of the first surface (S1), for example, 10 times or more or 20 times or more than the radius of curvature of the first surface (S1). In addition, the average of the radii of curvature of the first and second surfaces (S1, S2) of the first lens (111) may be larger than the average of the absolute values ​​of the radii of curvature of the lenses. The maximum effective length of the first lens (111) may be the second largest among the lenses. The effective length of the first surface (S1) of the first lens (111) may be larger than the average of the effective lengths of the object-side surfaces and the sensor-side surfaces of the second to sixth lenses (112-116). The maximum effective length of the first lens (111) may be the largest among lenses made of plastic material. The second surface (S2) of the first lens (111) may have at least one critical point in the area from the optical axis to the end of the effective area.

[0168]

[0169] On the optical axis, the third surface (S3) of the second lens (112) may have a concave shape, and the fourth surface (S4) may have a concave shape. The absolute value of the radius of curvature of the third surface (S3) on the optical axis may be greater than the radius of curvature of the fourth surface (S4). The difference in the radius of curvature (absolute value) of the third and fourth surfaces (S3, S4) may be 6 mm or less. On the optical axis (OA), the fifth surface (S5) of the third lens (114) may have a convex shape, and the sixth surface (S6) may have a convex shape. The seventh surface (S7) of the fourth lens (114) may have a concave shape, and the eighth surface (S8) may have a concave shape. On the optical axis (OA), the ninth surface (S9) of the fifth lens (115) may have a concave shape, and the tenth surface (S10) may have a convex shape. On the optical axis (OA), the eleventh surface (S11) of the sixth lens (116) may have a concave shape, and the twelfth surface (S12) may have a concave shape. The first to twelfth surfaces (S1-S12) are aspherical, and the conic constant (K) and the aspherical coefficients (AI) from the 4th to the 20th can be expressed as shown in FIG. 14.

[0170] On the optical axis (OA), the 13th surface (S13) of the seventh lens (117) may have a convex shape, and the 14th surface (S14) may have a convex shape. The seventh lens (117) has a convex shape on both sides, and can refract incident light into parallel light toward the image sensor (300). The 13th and 14th surfaces (S13, S14) of the seventh lens (117) are spherical, and the average of the absolute values ​​of the radii of curvature of the 13th and 14th surfaces (S13, S14) may be the second largest.

[0171] The absolute value difference in the radii of curvature between the object-side surface and the sensor-side surface of the third to sixth lenses (113, 114, 115, 116) may be 10 mm or less. Since the difference in the radii of curvature between the object-side surface and the sensor-side surface of these movable lenses is not set to be large, the change in the optical path can be predicted and the increase in the size of the lenses can be suppressed. In addition, the first lens (111) has the largest absolute value difference in the radii of curvature between the object-side surface and the sensor-side surface, so that the amount of incident light can be increased and refracted into the effective area of ​​the second lens (102). The refractive index of the seventh lens (117) may be the largest among the lenses. In addition, the difference in the absolute values ​​of the focal lengths of the first to seventh lenses (111-117) may be 17 mm or less.

[0172] The effective length (CA1) of the first lens (111) is the second longest among the lenses, and the effective length (CA5) of the fifth lens (115) is the shortest among the lenses. The effective length (CA1) of the first lens (111) may be 5 mm or more. The effective lengths (CA5, CA6) of the fifth and sixth lenses (115, 116) may be less than 5 mm. Since the center thickness (CT6) of the sixth lens (116) is less than 2 mm and the difference in the radius of curvature (absolute value) of both sides is provided small, light can be guided to the seventh lens (117) without significantly changing the path of the incident light.

[0173]

[0174] In the absolute value of the focal length, the focal length (F5) of the fifth lens (115) may be the largest among the lenses, and the difference (absolute value) in the focal length between adjacent two lenses may be the largest for the fifth and sixth lenses (115, 116), and the difference (absolute value) in the focal lengths of the second and third lenses (112, 113) may be the smallest. The focal lengths of the first to seventh lenses (111-117) may satisfy the following conditions.

[0175] Condition 1: │F2│ < F1 < │F2│*3

[0176] Condition 2: 0 < (│F2│ - F3) ≤ (│F4│- F3) < 6mm

[0177] Condition 3: │F6│ < F7 < F5

[0178] Condition 4: (│F2│ + F3 + │F6│) < F5

[0179] At least one of the central thicknesses (CT3, CT5) of the third and fifth lenses (113, 115) may be the thickest among the central thicknesses of the lenses, for example, 2 mm or more, and the central thickness (CT5) of the fifth lens (115) may be the largest. At least one of the central thicknesses (CT2, CT6) of the second and sixth lenses (112, 116) may be the thinnest among the central thicknesses of the lenses, so that the optical path can be adjusted according to the positional movement of the second and third lens groups (LG2, LG3).

[0180] The central thicknesses (CT3, CT4) of the third and fourth lenses (113, 114) of the second lens group (LG2) may each be greater than the sum of the central thicknesses (CT1, CT2) of the first and second lenses (111, 112). The sum of the central thicknesses (CT3, CT4) of the third and fourth lenses (113, 114) of the second lens group (LG2) may be greater than the sum of the central thicknesses (CT6, CT7) of the sixth and seventh lenses (116, 117). Accordingly, the second lens group (LG2) can guide light incident through the first lens group (LG1) to the effective area of ​​the third lens group (LG3).

[0181] The optical axis spacing (DG12) between the first and second lens groups (LG1, LG2), the optical axis spacing (DG23) between the second and third lens groups (LG2, LG3), and the optical axis spacing (DG34) between the third and fourth lens groups (LG3, LG4) may each be at least 0.5 mm and at most 8 mm depending on the change in magnification of the operating modes. Specifically, the optical axis spacing (DG12) between the first and second lens groups (LG1, LG2) may be at least 0.5 mm, for example, in the range of 0.5 mm to 7 mm. The optical axis spacing (DG23) between the second and third lens groups (LG2, LG3) may be at least 1 mm, for example, in the range of 1 mm to 3 mm. The optical axis distance (DG34) between the third and fourth lens groups (LG3, LG4) may be 0.8 mm or more, for example, in the range of 0.8 mm to 8 mm. In the first mode, DG12 and DG23, in the second mode, DG12, DG23, and DG34, and in the third mode, DG23 and DG34 may be greater than the BFL. The maximum movement distance (Max_mMd13) of the second and third lens groups (LG2, LG3) in the first, second, and third modes may satisfy 4 mm < Max_mMd13 ≤ 5.5 mm. Accordingly, the maximum movement distance for the zoom magnification can be reduced, thereby reducing the power consumption of the driving member.

[0182]

[0183] Depending on the operating mode, the F number of the optical system (1000) provides a brightness of 5 or less, and the F number may be in the range of 2.2 to 5. The aperture may be located between the first lens group (LG1) and the second lens group (LG2), and may be arranged, for example, around the fifth surface (S5) of the third lens (113).

[0184] Table 3 and FIG. 13 are for the items of the mathematical formulas described above in the optical system (1000) of the second embodiment, including the TTL (Total track length) (mm), BFL (Back focal length), effective focal length (F) (mm), focal length of each lens group, ImgH (mm), effective length (mm), center thickness (CT) of each lens, center spacing (CG) between two adjacent lenses, TD (mm), which is the optical axis distance from the first surface (S1) to the fourteenth surface (S14), focal lengths (F1, F2, F3, F4, F5, F6, F7) (mm) of each of the first to seventh lenses, diagonal angle of view (FOV) (Degree), F number, etc.

[0185] Item Example 2 Item Example 2 FLG1 (mm) - 23.850 TD (mm) 20.82 FLG2 (mm) 6.990 ImgH (mm) 5.6 FLG3 (mm) - 6.75 TTL (mm) 22.320 FLG4 (mm) 9.940 BFL (mm) 1.500

[0186] Table 4 can represent the effective focal length (F), field of view (FOV), F number, entrance pupil size (EPD), SD, and center spacing between adjacent lens groups (DG12, DG23, DG34) according to the first to third modes in the optical system according to the second embodiment. SD is the optical axis distance from the position of the aperture to the image sensor.

[0187] Example 2 Mode 1 Mode 2 Mode 3 F (mm) 12.65 18.95 25.25 DG 12 (mm) 5.75 03.08 00.900 DL G 23 (mm) 2.29 01.85 01.950 D G 34 (mm) 1.62 04.73 06.820 EPD (EPD1 / EPD2 / EPD3) 4.49 4.96 5.44 Fno (Fno1 / Fno2 / Fno3) 2.80 03.80 04.600 FOV (degrees) 25 17 13 SD 12.54 15.20 17.38

[0188]

[0189] As shown in Fig. 15, the optical system according to the second embodiment may have MTF characteristics according to the first, second, and third modes (Wide, Mid, Tele mode). In detail, Fig. 15 is a graph of the diffraction MTF characteristics of the optical system (1000) operating in the first to third modes, and it can be seen that the change in the position of defocusing according to the operating mode is not large. Figs. 16 to 18 are graphs measuring spherical aberration (Longitudinal Spherical Aberration), astigmatic field curves, and distortion from left to right in the aberration graph of the optical system according to the second embodiment. In Figs. 16 to 18, the X-axis may represent the focal length (mm) and the degree of distortion (%), and the Y-axis may represent the height of the image. Also, the graph for spherical aberration is a graph for light in the wavelength bands of approximately 435 nm, approximately 486 nm, approximately 546 nm, approximately 587 nm, and approximately 656 nm, and the graph for astigmatism and distortion is a graph for light in the wavelength band of 546 nm. In the aberration diagram, the closer each curve is to the Y-axis, the better the aberration correction function can be interpreted, and it can be seen that the aberration change according to the operation mode (Wide, Mid, Tele mode) is not large.

[0190]

[0191] <Third Example>

[0192] FIGS. 19 to 27 are drawings for explaining an optical system and a camera module having the same according to a third embodiment. When explaining a configuration according to the third embodiment, the same configuration as the first embodiment may include the configuration and description of the first embodiment. Referring to FIGS. 19 to 23, an optical system (1000) according to the third embodiment may include a lens unit (100B) having first to fourth lens groups (LG1, LG2, LG3, LG4). The first lens group (LG1) and the fourth lens group (LG4) are lens groups having fixed positions, and the second lens group (LG2) and the third lens group (LG3) are lens groups having variable positions.

[0193] The absolute value of the focal length of the first lens group (LG1) may be greater than the absolute values ​​of the focal lengths of the second, third, and fourth lens groups (LG2, LG3, and LG4). For example, the absolute value of the focal length of the first lens group (LG1) may be more than twice the focal length of the second lens group (LG2). The focal length of the second lens group (LG2) may be less than the focal length of the fourth lens group (LG4) and greater than the absolute value of the focal length of the third lens group (LG3). The focal length of the fourth lens group (LG4) may be greater than the absolute value of the focal length of the third lens group (LG3). The absolute value of the difference in the focal lengths of the second and third lens groups (LG2, LG3) may be 5 mm or less. The first and third lens groups (LG1, LG3) may have negative power on the optical axis, and the second and fourth lens groups (LG2, LG4) may have positive power on the optical axis.

[0194] The lens unit (100B) may include the first to seventh lenses (121-127). The first to seventh lenses (121-127) and the image sensor (300) may be sequentially arranged along the optical axis (OA) of the optical system (1000). The first lens group (LG1) may include the first and second lenses (121, 122). The second lens group (LG2) may include the third and fourth lenses (123, 124), the third lens group (LG3) may include the fifth and sixth lenses (125, 126), and the fourth lens group (LG4) may include the seventh lens (127).

[0195] The focal lengths of the first to fourth lens groups (LG1-LG4) can satisfy the following conditions.

[0196] Condition 1: FLG2*2 ≤ │FLG1│ < FLG2*5

[0197] Condition 2: FLG2 -│FLG3│ < FLG4 - FLG2

[0198] Condition 3: FLG4 < │FLG1│

[0199] Condition 4: FLG4 < (│FLG3│ + FLG2) < │FLG1│

[0200] The first and fourth lens groups (LG1, LG4) are fixed in position, and the second lens group (LG2) and the third lens group (LG3) are movable in the direction of the optical axis (OA), so that the optical system (1000) can provide various magnifications by moving the lens groups. The seventh lens (127) can control the incident angle of the principal ray to refract light parallel to the optical axis so that it is incident toward the image sensor (300).

[0201]

[0202] The first and second lenses (121, 122) can correct aberrations by having powers of opposite signs (+, -), and the third and fourth lenses (123, 124) can correct aberrations by having powers of opposite signs (+, -). The fifth and sixth lenses (125, 126) can correct aberrations by having powers of opposite signs (+, -). The first, second, fifth, and seventh lenses (121, 122, 125, and 127) can have positive (+) powers in the optical axis (OA). The second, fourth, and sixth lenses (122, 124, and 126) can have negative (-) powers in the optical axis (OA).

[0203] The material of the first lens (127) and the material of the second to seventh lenses (122-127) may be different from each other. The second to seventh lenses (122-127) may have an aspherical shape, and the first lens (121) may have a spherical shape. The material of the second to seventh lenses (122-127) may be a plastic material, and the first lens (121) may be a glass material. Since the first lens (121) is provided in a spherical shape made of glass, it is possible to prevent optical characteristics from being deteriorated due to heat and suppress surface damage.

[0204] On the optical axis, the first surface (S1) of the first lens (121) may have a convex shape, and the second surface (S2) may have a concave shape. The radius of curvature of the second surface (S2) on the optical axis may be larger than the radius of curvature of the first surface (S1), for example, three or four times or more the radius of curvature of the first surface (S1). In addition, the average of the radii of curvature of the first and second surfaces (S1, S2) of the first lens (121) may be larger than the average of the absolute values ​​of the radii of curvature of the lenses. The first and second surfaces (S1, S2) of the first lens (121) may have a spherical shape. The maximum effective length of the first lens (121) may be the second largest among the lenses. The effective length of the first surface (S1) of the first lens (121) may be greater than the average of the effective lengths of the object-side surfaces and the sensor-side surfaces of the second to sixth lenses (122-126). The maximum effective length of the seventh lens (127) may be the largest among the lenses, or may be the largest among the lenses made of plastic.

[0205]

[0206] On the optical axis, the third surface (S3) of the second lens (122) may have a concave shape, and the fourth surface (S4) may have a concave shape. The absolute value of the radius of curvature of the third surface (S3) on the optical axis may be smaller than the radius of curvature of the fourth surface (S4). The difference in the radius of curvature (absolute value) of the third and fourth surfaces (S3, S4) may be 4 mm or less. On the optical axis (OA), the fifth surface (S5) of the third lens (124) may have a convex shape, and the sixth surface (S6) may have a convex shape. The seventh surface (S7) of the fourth lens (124) may have a concave shape, and the eighth surface (S8) may have a concave shape. On the optical axis (OA), the ninth surface (S9) of the fifth lens (125) may have a concave shape, and the tenth surface (S10) may have a convex shape. On the optical axis (OA), the eleventh surface (S11) of the sixth lens (126) may have a concave shape, and the twelfth surface (S12) may have a concave shape. On the optical axis (OA), the thirteenth surface (S13) of the seventh lens (127) may have a convex shape, and the fourteenth surface (S14) may have a convex shape. The seventh lens (127) has a convex shape on both sides, and can refract incident light into parallel light toward the image sensor (300). The average of the absolute values ​​of the radii of curvature of the 13th and 14th surfaces (S13, S14) of the above-mentioned 7th lens (127) may be the second largest among the lenses. The above-mentioned 3rd to 14th surfaces (S3-S14) are aspherical, and the conic constant (K) and the aspherical coefficients (AI) from the 4th to the 20th may be expressed as shown in FIG. 23.

[0207] The absolute value difference of the radii of curvature between the object-side surface and the sensor-side surface of the third to sixth lenses (123, 124, 125, 126) may be 10 mm or less. Since the difference in the radii of curvature between the object-side surface and the sensor-side surface of these movable lenses is not set to be large, the change in the optical path can be predicted and the increase in the size of the lenses can be suppressed. In addition, since the absolute value difference in the radii of curvature between the object-side surface and the sensor-side surface of the first lens (121) is the largest, the amount of incident light can be increased and refracted into the effective area of ​​the second lens (122). The refractive index of at least one or all of the first, fifth, and seventh lenses (121, 125, 127) may be greater than the refractive index of the other lenses. In addition, the difference in the absolute values ​​of the focal lengths of the first to seventh lenses (121-127) may be 23 mm or less.

[0208] The effective length (CA1) of the first lens (121) is the second longest among the lenses, and the effective length (CA5) of the fifth lens (125) is the shortest among the lenses. The effective length (CA1) of the first lens (121) may be 5 mm or more. The effective lengths (CA5, CA6) of the fifth and sixth lenses (125, 126) may be less than 5 mm. Since the center thickness (CT6) of the sixth lens (126) is less than 2 mm and the difference in the radius of curvature (absolute value) of both sides is provided small, light can be guided to the seventh lens (127) without significantly changing the path of the incident light.

[0209] In the absolute value of the focal length, the focal length (F5) of the fifth lens (125) may be the largest among the lenses, and the difference (absolute value) in the focal length between adjacent two lenses may be the largest for the fifth and sixth lenses (125, 126), and the difference (absolute value) in the focal lengths of the second and third lenses (122, 123) may be the smallest. The focal lengths of the first to seventh lenses (121-127) may satisfy the following conditions.

[0210] Condition 1: │F2│ < F1 < │F2│*3

[0211] Condition 2: 0 < (│F2│ - F3) ≤ (│F4│- F3) < 6mm

[0212] Condition 3: │F6│ < F7 < F5

[0213] Condition 4: (│F2│ + F3 + │F6│) < F5

[0214] At least one of the central thicknesses (CT3, CT5) of the third and fifth lenses (123, 125) may be the thickest among the central thicknesses of the lenses, for example, 2 mm or more. At least one of the central thicknesses (CT2, CT6) of the second and sixth lenses (122, 126) may be the thinnest among the central thicknesses of the lenses, so that the optical path can be adjusted according to the positional movement of the second and third lens groups (LG2, LG3). Each of the central thicknesses (CT3, CT4) of the third and fourth lenses (123, 124) of the second lens group (LG2) may be greater than the sum of the central thicknesses (CT1, CT2) of the first and second lenses (121, 122). The sum of the central thicknesses (CT3) of the third lenses (123, 124) of the second lens group (LG2) may be greater than the sum of the central thicknesses (CT6, CT7) of the sixth and seventh lenses (126, 127). Accordingly, the second lens group (LG2) can guide light incident through the first lens group (LG1) to the effective area of ​​the third lens group (LG3).

[0215] The optical axis spacing (DG12) between the first and second lens groups (LG1, LG2), the optical axis spacing (DG23) between the second and third lens groups (LG2, LG3), and the optical axis spacing (DG34) between the third and fourth lens groups (LG3, LG4) may each be at least 0.5 mm and at most 8 mm depending on the change in magnification of the operating modes. Specifically, the optical axis spacing (DG12) between the first and second lens groups (LG1, LG2) may be at least 0.5 mm, for example, in the range of 0.5 mm to 7 mm. The optical axis spacing (DG23) between the second and third lens groups (LG2, LG3) may be at least 1 mm, for example, in the range of 1 mm to 3 mm. The optical axis distance (DG34) between the third and fourth lens groups (LG3, LG4) may be 0.8 mm or more, for example, in the range of 0.8 mm to 8 mm. In the first mode, DG12 and DG23, in the second mode, DG12, DG23, and DG34, and in the third mode, DG23 and DG34 may be greater than the BFL. The maximum movement distance (Max_mMd13) of the second and third lens groups (LG2, LG3) in the first, second, and third modes may satisfy 4 mm < Max_mMd13 ≤ 5.5 mm. Accordingly, the maximum movement distance for the zoom magnification can be reduced, thereby reducing the power consumption of the driving member.

[0216] Depending on the operating mode, the F number of the optical system (1000) provides a brightness of 5 or less, and the F number may be in the range of 2.2 to 5. The aperture may be located between the first lens group (LG1) and the second lens group (LG2), and may be arranged, for example, around the fifth surface (S5) of the third lens (123).

[0217] Table 5 and FIG. 22 show the items of the mathematical formulas described above in the optical system (1000) of the third embodiment, including the TTL (Total track length) (mm), BFL (Back focal length), effective focal length (F) (mm), focal length of each lens group, ImgH (mm), effective length (mm), center thickness (CT) of each lens, center spacing (CG) between two adjacent lenses, TD (mm), which is the optical axis distance from the first surface (S1) to the fourteenth surface (S14), focal lengths (F1, F2, F3, F4, F5, F6, F7) (mm) of each of the first to seventh lenses, diagonal angle of view (FOV) (Degree), F number, etc.

[0218] Item Example 3 Item Example 3 FLG1 (mm) - 25.150 TD (mm) 20.82 FLG2 (mm) 6.940 ImgH (mm) 5.6 FLG3 (mm) - 6.12 TTL (mm) 22.320 FLG4 (mm) 10.240 BFL (mm) 1.500

[0219] Table 6 can represent the effective focal length (F), field of view (FOV), F number, entrance pupil size (EPD), SD, and center spacing between adjacent lens groups (DG12, DG23, DG34) according to the first to third modes in the optical system according to the third embodiment. SD is the optical axis distance from the position of the aperture to the image sensor.

[0220] Example 3 Mode 1 Mode 2 Mode 3 F (mm) 12.65 22.32 22.32 DG 12 (mm) 5.69 03.04 00.860 DL G 23 (mm) 2.01 01.62 01.700 D G 34 (mm) 1.24 04.28 06.380 EPD (EPD1 / EPD2 / EPD3) 4.49 4.96 5.44 Fno (Fno1 / Fno2 / Fno3) 2.80 03.80 04.600 FOV (degrees) 25 17 13 SD 12.54 15.20 17.38

[0221] As shown in Fig. 24, the optical system according to the third embodiment may have MTF characteristics according to the first, second, and third modes (Wide, Mid, Tele mode). In detail, Fig. 24 is a graph of the diffraction MTF characteristics of the optical system (1000) operating in the first to third modes, and it can be seen that the change in the position of defocusing according to the operating mode is not large. Figs. 25 to 27 are graphs measuring spherical aberration (Longitudinal Spherical Aberration), astigmatic field curves, and distortion from left to right in the aberration graph of the optical system according to the third embodiment. In Figs. 25 to 27, the X-axis may represent the focal length (mm) and the degree of distortion (%), and the Y-axis may represent the height of the image. Also, the graph for spherical aberration is a graph for light in the wavelength bands of approximately 435 nm, approximately 486 nm, approximately 546 nm, approximately 587 nm, and approximately 656 nm, and the graph for astigmatism and distortion is a graph for light in the wavelength band of 546 nm. In the aberration diagram, the closer each curve is to the Y-axis, the better the aberration correction function can be interpreted, and it can be seen that the aberration change according to the operation mode (Wide, Mid, Tele mode) is not large.

[0222] The optical system (1000) according to the first to third embodiments can satisfy at least one or two or more of the mathematical equations described below. Accordingly, the optical system (1000) according to the first to third embodiments can effectively correct aberrations that change according to changes in the operation mode. The optical system (1000) can adjust the zoom magnification for a subject at various magnifications and can have a slim and compact structure.

[0223] Hereinafter, the optical axis spacing between adjacent two lenses can be defined as CG1-CG7 from the spacing between the first and second lenses to the spacing between the seventh and eighth lenses. The effective lengths of the object-side surface and the sensor-side surface of the first lens (101) to the major axis effective lengths of the object-side surface and the sensor-side surface of the seventh lens (107) can be defined as CA11, CA12 to CA81, CA82. The units of the thickness, spacing, and effective diameter values ​​are mm. In addition, the effective length includes a circular or non-circular shape of the lens surface, and can be defined as the major axis effective length or the maximum effective length when the lens has a partially circular shape.

[0224] [Mathematical Formula 1] nLG2 > 1

[0225] In mathematical expression 1, nLG2 represents the number of lenses included in the second lens group (LG2). Here, the relationship nLG1, nLG2, nLG3 > nLG4 may be present. Here, n represents the number of lenses.

[0226] [Equation 2] 0.75 < CA1 / CA7 < 0.98

[0227] In mathematical expression 2, CA1 is the average of the maximum effective lengths of the object-side and sensor-side surfaces of the first lens (101, 111, 121), and CA7 is the average of the maximum effective lengths of the object-side and sensor-side surfaces of the seventh lens (107, 117, 127). When mathematical expression 2 is satisfied, TTL can be reduced. Preferably, 0.8 < CA1 / CA7 < 0.9 can be satisfied.

[0228] [Mathematical Formula 2-1] 0.75 < CA11 / CA72 < 0.98

[0229] In mathematical expression 2-1, CA11 is the average of the maximum effective lengths of the object-side surfaces of the first lens (101, 111, 121), and CA72 is the average of the maximum effective lengths of the sensor-side surfaces of the seventh lens (107, 117, 127). Preferably, 0.8 < CA11 / CA72 < 0.9 can be satisfied. When mathematical expressions 2 and 2-1 are satisfied, a high entrance pupil size (EPD: Entrance Pupil Diameter, EPD) compared to the optical system can be provided.

[0230] [Mathematical Formula 3] 0 < CT1 / CT3 < 1

[0231] In mathematical expression 3, the center thickness (CT1) of the first lens (101, 111, 121) may be smaller than the center thickness (CT3) of the third lens (103, 113, 123), and when this is satisfied, the aberration characteristics in the optical system (1000) may be improved. Preferably, 0.2 < CT1 / CT3 < 0.7 may be satisfied. The third lens (103, 113, 123) has a center thickness (CT3) of 2 mm or more and a convex shape on both sides, so that the third lens can improve the light incident efficiency of the first lens group (LG1) and refract the light into the effective area of ​​the fifth lens having the smallest effective length.

[0232] [Mathematical Formula 4] 0 < CT1 / CT4 < 1

[0233] In mathematical expression 4, the central thickness of the first lens (101, 111, 121) may be smaller than the central thickness (CT4) of the fourth lens (104, 114, 124), and when this is satisfied, the optical system (1000) can improve the aberration characteristics. Preferably, 0.2 < CT1 / CT4 < 0.8 can be satisfied. Since the central thickness (CT4) of the fourth lens (104, 114, 124) is thicker than 1.5 mm and has a concave shape on both sides, the central gap between the third and fourth lenses can be further reduced.

[0234] [Mathematical Formula 5] L1R1*L2R1 < 0

[0235] L1R1 is the radius of curvature of the object-side surface of the first lens (101, 111, 121), and L2R1 is the radius of curvature of the object-side surface of the second lens. When the optical system satisfies mathematical expression 4, the amount of incident light can be increased, and for example, the incidence efficiency of reflected light in the entire area of ​​the reflective member (400 in Fig. 29) can be improved.

[0236] [Equation 6] FLG1 < 0

[0237] In mathematical expression 6, FLG1 is the effective focal length (EFL) of the first lens group (LG1), and can have a value less than 0. FLG1 is the composite focal length of the first and second lenses. When mathematical expression 6 is satisfied, the optical aberration of the optical system, i.e., the optical aberration of the first lens group (LG1), can be improved.

[0238] [Mathematical Formula 7] 1° < CRA < 20°

[0239] In mathematical expression 7, CRA (Chief Ray Angle) is the chief ray incident angle. In the optical system, the incident angle of the chief ray may be less than 20 degrees at most, and may be 15 degrees or less, depending on the first, second, and third modes. The first mode may be a wide mode, the second mode may be a middle mode, and the third mode may be a tele mode. When mathematical expression 6 is satisfied, the peripheral light ratio can be secured.

[0240] [Equation 8] (TTL / DLG1) > 3.5

[0241] In mathematical expression 8, DLG1 is the optical axis distance of the first lens group (LG1), for example, the optical axis distance from the center of the object-side surface of the first lens (101, 111, 121) to the center of the sensor-side surface of the second lens (102, 112, 122). For example, DLG1 means the distance (mm) from the optical axis (OA) of the first surface (S1) of the first lens (101, 111, 121) to the fourth surface (S4) of the second lens (102, 112, 122). TTL (Total track length) means the distance (mm) from the object-side first surface (S1) of the first lens (101, 111, 121) to the upper surface of the image sensor (300) on the optical axis (OA). When the optical system (1000) satisfies mathematical expression 8, the optical system (1000) has a relatively small TTL and can secure a peripheral light ratio. Mathematical expression 8 may further include the following mathematical expression.

[0242] [Mathematical Formula 8-1] (TTL / DLG1) < (TTL / DLG2)

[0243] [Equation 8-2] DLG3 < DLG2

[0244] Here, DLG2 is the optical axis distance of the second lens group (LG2), and is the distance from the center of the object-side surface of the third lens (103, 113, 123) to the center of the sensor-side surface of the fourth lens (104, 114, 124). DLG3 is the optical axis distance of the third lens group (LG3), and is the distance from the center of the object-side surface of the fifth lens (106, 116, 126) to the center of the sensor-side surface of the sixth lens (106, 116, 126).

[0245] [Equation 9] 2 < TTL / EPD3 < 7

[0246] In mathematical expression 9, EPD3 refers to the size of the entrance pupil (EPD) of the optical system (1000) when operating in the third mode, i.e., Tele mode. When the optical system (1000) satisfies mathematical expression 9, the optical system (1000) can secure a bright image when operating in the third mode, and this can be a minimum condition for securing an F number of 5 or less in Tele mode. Preferably, 3 < TTL / EPD3 < 5 can be satisfied.

[0247] [Equation 9-1] 4 < TTL / EPD1 < 7

[0248] [Equation 9-2] 3.5 < TTL / EPD2 < 6.5

[0249] In mathematical expressions 9-1 and 9-2, EPD1 is the size of the entrance pupil of the optical system in the first mode (Wide), and EPD2 is the size of the entrance pupil of the optical system in the second mode (Middle). When the optical system satisfies the above conditions, it can secure a bright image in each mode.

[0250] [Equation 10] 2 < CT_Max / CT_Min < 6

[0251] In mathematical expression 10, CT_Max is the thickest thickness among the central thicknesses of the lenses, and CT_Min is the thinnest thickness among the central thicknesses of the lenses. If mathematical expression 10 is satisfied, the optical system aberration characteristics can be improved. Preferably, 4 < CT_Max / CT_Min < 5.5 can be satisfied.

[0252] [Mathematical Formula 11] 1 < CA_Max / CA_Min < 3

[0253] In mathematical expression 11, CA_Max is the largest effective length or the effective length in the major axis direction among each lens surface, and CA_Min is the smallest effective diameter among each lens surface. When mathematical expression 11 is satisfied, a camera module for a slim or compact structure can be provided while maintaining the optical performance of the optical system. Preferably, 1.2 < CA_Max / CA_Min < 1.8 can be satisfied.

[0254]

[0255] [Equation 12] 0.3 < ΣCG / TTL < 0.8

[0256] In mathematical expression 12, ΣCG is the sum of the center spacings between adjacent lenses, and the sum of the center spacings according to the change in the first to third modes can be constant. When the optical system satisfies mathematical expression 12, the movement distance of the second and third lens groups (LG2, LG3) and the center spacing between adjacent lenses within each lens group can be set according to each mode. Preferably, 0.4 < ΣCG / TTL < 0.7 can be satisfied.

[0257] [Mathematical Formula 13] 0.25 < DLG1 / DLG2 < 0.8

[0258] In mathematical expression 13, DLG1 is the optical axis distance of the first lens group (LG1), and DLG2 is the optical axis distance of the second lens group (LG2). By setting the optical axis distances of the first and second lens groups (LG1, LG2) in mathematical expression 13, TTL can be adjusted. Preferably, 0.4 < DLG1 / DLG2 < 0.65 can be satisfied.

[0259] [Mathematical Formula 14] 0.5 < DLG2 / DLG3 < 2

[0260] In mathematical expression 14, DLG2 is the optical axis distance of the second lens group (LG2), and DLG3 is the optical axis distance of the third lens group (LG3). Preferably, 1 < DLG2 / DLG3 < 1.5 can be satisfied. When the optical system (1000) according to the embodiment satisfies at least one of mathematical expressions 13 and 14, it has a relatively small TTL and can provide various magnifications according to at least three mode changes.

[0261] [Equation 15] 0 < CG1 / TTL < 0.2

[0262] In mathematical expression 15, CG2 is the optical axis distance between the first lens (101, 111, 121) and the second lens (102, 112, 122). When the optical system (1000) satisfies mathematical expression 15, the optical system (1000) has a relatively small TTL and can have improved optical characteristics by controlling stray light incident on the first lens group (LG1). Preferably, 0 < CG2 / TTL < 0.1 can be satisfied.

[0263] [Mathematical Formula 16] 2 < TTL / (DLG2+DLG3) < 5

[0264] Mathematical expression 16 sets the sum of the optical axis distances of the TTL and the second and third lens groups (LG2, LG3), and when the optical system (1000) satisfies Mathematical expression 16, the optical system (1000) has a relatively small TTL and can improve chromatic aberration characteristics. Preferably, 2.5 < TTL / (DLG2+DLG3) < 3.5 can be satisfied.

[0265] [Equation 17] 20 < |Vd2 - Vd3| < 70

[0266] In mathematical expression 17, Vd2 represents the Abbe number of the second lens (102, 112, 122), and Vd3 represents the Abbe number of the third lens (103, 113, 123). When the absolute value of the difference in Abbe numbers between the second and third lenses of the optical system (1000) according to the embodiment satisfies mathematical expression 17, the optical system (1000) can improve chromatic aberration characteristics. Preferably, Vd2 < Vd3 is satisfied, and 45 < Vd3 can be satisfied.

[0267] [Equation 18] 15 < |Vd6 - Vd7| < 60

[0268] In mathematical expression 18, Vd7 represents the Abbe number of the seventh lens, and Vd6 represents the Abbe number of the sixth lens. When the absolute value of the difference in Abbe numbers between the sixth and seventh lenses satisfies mathematical expression 18, the optical system (1000) can improve chromatic aberration characteristics. Preferably, Vd7 < Vd6 is satisfied, and 45 < Vd6 can be satisfied.

[0269] [Equation 19] 1.6 < Nd1

[0270] In mathematical expression 19, Nd1 represents the refractive index of the first lens (101, 111, 121) at the d-line. When the optical system (1000) according to the embodiment satisfies mathematical expression 19, the incident light can be dispersed, and the effective area of ​​the lens arranged on the sensor side relative to the first lens (101, 111, 121) can be secured. Preferably, 1.65 ≤ Nd1 can be satisfied.

[0271] [Equation 19-1] 1.6 < Nd2

[0272] [Equation 19-2] 1.6 < Nd5

[0273] [Equation 19-3] 1.6 < Nd7

[0274] The refractive indices of the above-described second, fifth, and seventh lenses may be greater than 1.6. The number of lenses having a refractive index of 1.60 or greater within the lens unit may be three or more, for example, four. Here, the product of the Abbe number of the first lens (101, 111, and 121) and the Abbe number and refractive index of the seventh lens (107, 117, and 127) is as follows.

[0275] Condition 1: Nd1*Vd1 < 50 Condition 2: Nd7*Vd7 < 50

[0276]

[0277] [Mathematical Formula 20] 0.5 < L1R1 / L2R2 < 1.5

[0278] In mathematical expression 20, L1R1 denotes the radius of curvature of the object-side first surface (S1) of the first lens (101, 111, 121), and L2R2 denotes the radius of curvature of the sensor-side fourth surface (S4) of the second lens (102, 112, 122). When the optical system (1000) satisfies mathematical expression 20, the optical system (1000) can control stray light incident on the first lens group (LG1). Preferably, 1 < L1R1 / L2R2 < 1.3 can be satisfied. Since the second lens (102, 112, 122) has a concave sensor-side surface on the optical axis, the effective diameter of the third lens (103, 113, 123) can be suppressed from increasing.

[0279] [Mathematical Formula 21] 1 < L1R1 / L3R1 < 3.5

[0280] In mathematical expression 21, L1R1 denotes the radius of curvature of the object-side first surface (S1) of the first lens (101, 111, 121), and L3R1 denotes the radius of curvature of the object-side fifth surface (S5) of the fourth lens (103, 113, 123). When the optical system (1000) according to the embodiment satisfies mathematical expression 21, the optical system (1000) can have good optical performance at various magnifications. Preferably, 1.5 < L1R1 / L3R1 < 2.5 can be satisfied.

[0281] [Mathematical Formula 22] 1 < L2R2 / L3R1 < 3

[0282] In mathematical expression 22, L2R2 denotes the radius of curvature of the fourth surface (S4) on the sensor side of the second lens (102, 112, 122). When the optical system (1000) according to the embodiment satisfies mathematical expression 22, the optical system (1000) can have good optical performance at the periphery of the field of view (FOV) when operating at various magnifications of at least three modes. Preferably, 1.5 < L2R2 / L3R1 < 2.5 can be satisfied. The third lens (103, 113, 123) is the lens closest to the first lens group (LG1) in the second lens group (LG2), has a biconvex shape on the optical axis, and can have positive power. Accordingly, the gap between the convex sensor-side surface of the third lens (103, 113, 123) and the concave object-side surface of the fourth lens (104, 114, 124) can be made close.

[0283] [Equation 23] -0.8 < L1R1 / L7R2 < -0.3

[0284] In mathematical expression 23, L7R2 represents the radius of curvature of the sensor-side 14th surface (S14) of the seventh lens (107, 117, 127). When the optical system (1000) satisfies mathematical expression 23, the radius of curvature of the sensor-side surface of the last lens can be set.

[0285] [Equation 23-1] 1 < │L7R1 / L1R1│

[0286] In mathematical expression 23-1, the central thickness of the first lens (101, 111, 121) can be reduced by the small radius of curvature of the object-side surface of the first lens, and the central thickness of the seventh lens can be increased by the large radius of curvature of the object-side surface of the seventh lens, so that light incident by the seventh lens can be refracted toward the image sensor (300) in an almost parallel manner.

[0287] [Equation 24] 0 < Md12_mLG2 / TTL < 0.5

[0288] In mathematical expression 24, Md12_mLG2 means the difference in the center spacing (unit: mm) after the movement of the second lens group (LG2) when changing from the second mode to the first mode or from the first mode to the second mode. In detail, the Md12_mLG2 represents the movement distance of the second lens group (LG2) in the first and second modes, and means the difference value between the optical axis spacing between the first and second lens groups (LG1, LG2) in the first mode and the optical axis spacing between the first and second lens groups (LG1, LG2) in the second mode. When the optical system (1000) satisfies mathematical expression 24, the optical system (1000) can minimize the movement distance of the second lens group (LG2) when the magnification is changed, so that the optical system (1000) can have a slim structure. In addition, the movement distance can be minimized when controlling the position of the second lens group (LG2), thereby providing improved power consumption characteristics. Preferably, 0 < Md12_mLG2 / TTL < 0.2 can be satisfied.

[0289] [Equation 25] 0 < Md23_mLG2 / TTL < 0.5

[0290] In mathematical expression 25, Md23_mLG2 refers to the difference in the center spacing (unit: mm) after movement of the second lens group (LG2) when operating from the second mode to the third mode, or from the third mode to the second mode. Specifically, Md23_mLG2 refers to the difference value between the optical axis spacing between the first and second lens groups (LG1, LG2) in the second mode and the optical axis spacing between the first and second lens groups (LG1, LG2) in the third mode. The maximum movement distance of the second lens group (LG2) may be greater than the maximum movement distance of the third lens group (LG3). When the optical system (1000) according to the embodiment satisfies mathematical expression 25, the optical system (1000) can minimize the movement distance of the second lens group (LG2) when the magnification is changed, so that the optical system (1000) can have a slim structure. In addition, the movement distance can be minimized when controlling the position of the second lens group (LG2), thereby providing improved power consumption characteristics. 0.1 < Md23_mLG2 / TTL < 0.2 can be satisfied. In addition, the condition of Md12_mLG2 < Md23_mLG2 can be satisfied.

[0291] [Mathematical Formula 26] 0.3 < Md12_mLG2 / DLG2 < 1

[0292] Mathematical expression 26 can set the movement distance of the second lens group (LG2) and the optical axis distance of the second lens group (LG2). When the optical system (1000) satisfies Mathematical expression 26, the optical system (1000) can minimize the movement distance of the second lens group (LG2) when the magnification is changed, so that the optical system (1000) can have a slim structure. In addition, the movement distance can be minimized when controlling the position of the second lens group (LG2), so that it can have improved power consumption characteristics. Preferably, 0.4 < Md12_mLG2 / DLG2 < 0.75 can be satisfied.

[0293] [Equation 27] 0.3 < Md23_mLG3 / DLG3 < 0.9

[0294] In mathematical expression 27, Md23_mLG3 refers to the difference in the center spacing after the movement of the third lens group (LG3) when changing from the second mode to the third mode, or from the third mode to the second mode. When the optical system (1000) satisfies mathematical expression 27, the optical system (1000) can minimize the movement distance of the third lens group (LG3) when the magnification is changed, so that the optical system (1000) can have a slim structure. In addition, the movement distance can be minimized when controlling the position of the third lens group (LG3), so that it can have improved power consumption characteristics. Preferably, 0.4 < Md23_mLG3 / DLG3 < 0.8 can be satisfied.

[0295] [Equation 28] 0 < Md23_mLG3 / TTL < 0.5

[0296] In mathematical expression 25, Md23_mLG3 refers to the difference in the center spacing (unit: mm) after movement of the third lens group (LG3) when operating from the second mode to the third mode, or from the third mode to the second mode. Specifically, Md23_mLG3 refers to the difference value between the optical axis spacing between the second and third lens groups (LG2, LG3) in the second mode and the optical axis spacing between the second and third lens groups (LG2, LG3) in the third mode. When the optical system (1000) satisfies mathematical expression 25, the optical system (1000) can minimize the movement distance of the third lens group (LG3) when the magnification is changed, so that the optical system (1000) can have a slim structure. In addition, since the movement distance can be minimized when controlling the position of the third lens group (LG3), it can have improved power consumption characteristics. 0 < Md23_mLG3 / TTL < 0.2 can be satisfied.

[0297] [Mathematical Formula 29] 1 < Md12_mLG3 / DLG3 < 3

[0298] Mathematical expression 26 can set the movement distance of the third lens group (LG3) and the optical axis distance of the third lens group (LG3). When the optical system (1000) satisfies Mathematical expression 26, the optical system (1000) can minimize the movement distance of the third lens group (LG3) when the magnification is changed, so that the optical system (1000) can have a slim structure. In addition, the movement distance can be minimized when controlling the position of the third lens group (LG3), so that it can have improved power consumption characteristics. Preferably, 1.2 < Md12_mLG3 / DLG3 < 2 can be satisfied.

[0299] [Mathematical Formula 30] 1 < Md1(DG12 / DG23) < 5

[0300] In mathematical expression 30, Md1(DG12 / DG23) represents the ratio between the center spacing (DG12) between the first and second lens groups in the first mode and the center spacing (DG23) between the second and third lens groups. When the optical system (1000) according to the embodiment satisfies mathematical expression 30, the optical system (1000) may have improved optical characteristics at the first magnification. In detail, the optical system (1000) may have improved aberration characteristics at the first magnification and may improve optical performance at the center and periphery of the field of view (FOV). Preferably, 2 < Md1(DG12 / DG23) < 3.3 may be satisfied.

[0301] [Equation 31] 0.2 < Md3(DG12 / DG23) < 0.9

[0302] In mathematical expression 31, Md3(DG12 / DG23) represents the ratio between the center spacing (DG12) between the first and second lens groups in the third mode and the center spacing (DG23) between the second and third lens groups. When the optical system (1000) according to the embodiment satisfies mathematical expression 31, the optical system (1000) can have improved optical characteristics at the second magnification. In detail, the optical system (1000) can have improved aberration characteristics at the second magnification and improve the optical performance of the peripheral part of the field of view (FOV). Preferably, 0.3 < Md3(DG12 / DG23) < 0.7 can be satisfied.

[0303] [Equation 32] 2 < Md_CG_Max / Md_CG_Min < 8

[0304] Md_CG_Max is the maximum center spacing between adjacent lenses when the second and third lens groups (LG2, LG3) move according to the first to third modes, and Md_CG_Min is the minimum center spacing between adjacent lenses. When mathematical expression 32 is satisfied, the center spacing between lenses in an optical system having a variable lens group can be set, and the moving distance can be adjusted.

[0305] [Mathematical Formula 33] 1mm < Max_mMd13 < 7mm

[0306] Max_mMd13 represents the maximum movement distance when the second and third lens groups move from the first mode to the third mode or from the third mode to the first mode. When the optical system satisfies mathematical expression 33, the power consumption of the driving element can be reduced.

[0307]

[0308] [Equation 34] 5 < TTL / Max_mLG2 < 5.6

[0309] Max_mLG2 is the maximum travel distance of the second lens group (LG2). If the optical system satisfies Equation 34, the power consumption according to the travel distance of the second lens group (LG2) can be reduced compared to TTL.

[0310] [Equation 35] 5.2 < TTL / Max_mLG3 < 5.8

[0311] Max_Mlg3 is the maximum travel distance of the third lens group (LG3). If the optical system satisfies Equation 35, the power consumption according to the travel distance of the third lens group (LG3) can be reduced compared to TTL.

[0312] [Mathematical Formula 36] 0.5mm ≤ Md3_DG12 < 1.5mm

[0313] Md3_DG12 is the center spacing between the first and second lens groups when in the third mode. When the optical system satisfies mathematical expression 36, when the first and second lens groups (LG1, LG2) are in the tele mode with the closest center spacing, the center spacing between the first and second lens groups (LG1, LG2) is set to be 0.5 mm or more, thereby reducing the power consumption of the driving member and suppressing light loss. Preferably, 0.5 mm ≤ Md3_DG12 < 1 mm can be satisfied.

[0314] [Equation 37] LG1_Vd2 < 35

[0315] LG1_Vd2 is the Abbe number of the second lens in the first lens group, for example, the Abbe number of the second lens. If the optical system satisfies Equation 37, it can correct aberration characteristics or correct aberration characteristics that change due to movement of other lens groups.

[0316] [Equation 38] LG3_Vd1 < 35

[0317] LG3_Vd1 is the Abbe number of the first lens in the third lens group, for example, the Abbe number of the fifth lens. If the optical system satisfies Equation 38, the aberration characteristics caused by the fifth and sixth lenses can be corrected.

[0318] [Equation 39] LG4_Nd > 1.6

[0319] LG4_Nd1 is the refractive index of the lens of the fourth lens group, for example, the refractive index of the seventh lens. When the optical system satisfies mathematical expression 39, the chromatic dispersion can be adjusted to cover a BFL of less than 3 mm, thereby irradiating light to the entire area of ​​the image sensor (300).

[0320] [Equation 40] 20 < Aver_Vd < 50

[0321] In mathematical expression 40, Aver_Vd is the average Abbe number of the first to seventh lenses. When the optical system satisfies mathematical expression 40, the optical system (1000) can have improved aberration characteristics and resolution. Preferably, 25 < Aver_Vd < 35 can be satisfied.

[0322] [Equation 41] 1.5 < Aver_Nd < 1.8

[0323] In mathematical expression 40, Aver_Nd is the average refractive index of the first to seventh lenses. When the optical system satisfies mathematical expression 41, the optical system (1000) can have improved aberration characteristics and resolution. Preferably, 1.6 < Aver_Nd < 1.67 can be satisfied.

[0324] [Equation 41-1] 10 < ΣVd / ΣNd < 30

[0325] In mathematical expression 41-1, ΣVd means the sum of the Abbe numbers of each of the plurality of lenses. ΣNd means the sum of the refractive indices of each of the plurality of lenses. When the optical system (1000) according to the embodiment satisfies mathematical expression 41-1, the optical system (1000) can have improved aberration characteristics and resolution. Preferably, mathematical expression 41-1 can satisfy 17 < ΣVd / ΣNd < 25.

[0326]

[0327] [Equation 42] 2 < │ FLG1 / FLG2 │ < 4

[0328] In mathematical expression 42, FLG1 represents the effective focal length (EFL) of the first lens group (LG1), and FLG2 represents the effective focal length of the second lens group (LG2). FLG2 is the composite focal length of the fourth and fifth lenses. When mathematical expression 42 is satisfied, the size of the optical system, for example, the total track length (TTL), can be reduced. Preferably, FLG2 > 0 is satisfied. FLG3 is the composite focal length of the sixth and seventh lenses, and FLG3 < 0 can satisfy the condition │FLG1│ >│FLG4│ > FLG2. FLG4 is the focal length of the fourth lens group or the seventh lens.

[0329] [Mathematical Formula 43] 1 < FMd3 / FMd1 < 3

[0330] In mathematical expression 43, FMd1 is the effective focal length of the optical system in the first mode, and FMd3 is the effective focal length of the optical system in the third mode. Preferably, 1.5 < FMd3 / FMd1 < 2.5 can be satisfied. When the optical system satisfies mathematical expression 43, the effective focal length can be adjusted according to the first and third modes.

[0331] [Equation 44] 2 < FMd2 / EPD2 < 6

[0332] In mathematical expression 44, FMd2 is the effective focal length of the optical system in the second mode (Middle), and EPD2 refers to the size of the entrance pupil of the optical system (1000) in the second mode. When the optical system (1000) according to the embodiment satisfies mathematical expression 44, the optical system (1000) can secure a bright image when operating in the second mode. Preferably, 3 < FMd2 / EPD2 < 5 can be satisfied.

[0333] [Mathematical Formula 45] 1 < FMd1 / EPD1 < 4

[0334] In mathematical expression 34, FMd1 is the effective focal length of the optical system in the first mode (Wide), and EPD1 refers to the size of the entrance pupil of the optical system (1000) when operating in the first mode. When the optical system (1000) according to the embodiment satisfies mathematical expression 45, the optical system (1000) can secure a bright image when operating in the first mode. Preferably, 2 < FMd1 / EPD1 < 3.5 can be satisfied.

[0335] [Mathematical Formula 46] FMd < FMd2 < FMd3

[0336] In mathematical expression 46, FMd1, FMd2, and FMd3 represent the effective focal lengths of the optical system in the first, second, and third modes. The effective focal length in the third mode may be the largest, and the effective focal length in the first mode may be the smallest.

[0337]

[0338] [Mathematical Formula 47] 0.8 < TTL / FMd2 < 2

[0339] Mathematical expression 47 can adjust TTL by comparing the effective focal length in TTL and the second mode. Preferably, 1 ≤ TTL / FMd2 < 1.5 can be satisfied.

[0340] [Mathematical Formula 48] 1 < TTL / FMd1 < 3

[0341] Mathematical expression 47 can adjust TTL by comparing the effective focal length in TTL and the first mode. Preferably, 1.5 < TTL / FMd1 < 2 can be satisfied.

[0342] [Equation 49] 1 < CA_Max / ImgH < 3

[0343] In mathematical expression 49, CA_Max refers to the largest effective length (CA) among the lens surfaces of the plurality of lenses included in the optical system (1000). ImgH refers to the distance from the 0 field area of ​​the image surface center of the image sensor (300) overlapping with the optical axis (OA) to the 1.0 field area of ​​the image sensor (300). The ImgH refers to half of the maximum diagonal length of the effective area of ​​the image sensor (300). When the optical system (1000) according to the embodiment satisfies mathematical expression 49, the optical system (1000) can be provided in a slim and compact manner. In addition, the optical system (1000) can implement high resolution and high image quality. The range of the ImgH is greater than 2 mm, for example, in the range of 2 mm to 4 mm. Here, the effective lengths (CA1-CA7) of the first to seventh lenses (101-107) can satisfy the following conditions.

[0344] Condition 1: CA6 < (Imgh*2) < CA7

[0345] Condition 2: CA2 < (Imgh*2)

[0346] Condition 3: CA2 < CA1

[0347] Condition 4: CA5 < CA4

[0348] CA1-CA7 is the average of the maximum effective lengths of the object-side and sensor-side surfaces of the first to seventh lenses, respectively.

[0349] [Mathematical Formula 50] 5 < TTL / ImgH < 12

[0350] When the optical system (1000) satisfies mathematical expression 39, the optical system (1000) can have a smaller TTL, so that the optical system (1000) can be provided in a slim and compact manner. Preferably, it can be in the range of 6 < TTL / ImgH < 10.

[0351] [Equation 51] 0 < BFL / ImgH < 1

[0352] When the optical system (1000) according to the embodiment satisfies mathematical expression 51, it is possible to secure BFL required for a high-pixel (e.g., 48 Mega or more) or 2-inch or larger image sensor. In addition, when the optical system (1000) satisfies mathematical expression 51, the optical system (1000) can operate at various magnifications while maintaining TTL, and can have excellent optical characteristics at the center and periphery of the field of view (FOV).

[0353]

[0354] [Equation 52] 2 < FMd1 / ImgH < 6

[0355] When the optical system (1000) according to the embodiment satisfies mathematical expression 52, the effective focal length of the first mode can be set according to the effective length of the image sensor. Preferably, 4 < FMd1 / ImgH < 5 can be satisfied.

[0356] [Equation 53] 6 < FMd3 / ImgH < 12

[0357] When the optical system (1000) according to the embodiment satisfies mathematical expression 53, the effective focal length of the third mode can be set according to the effective length of the image sensor. Preferably, 7 < FMd3 / ImgH < 11 can be satisfied.

[0358] [Mathematical Formula 54] 2mm < ImgH

[0359] Mathematical expression 56 can set half of the diagonal length of the image sensor (300) and provide the size of the image sensor of the zoom magnification optical system. Mathematical expression 54 can preferably satisfy 2.40 mm < ImgH < 4 mm.

[0360] [Mathematical Formula 55] 10mm < F < 40mm

[0361] F is the range of the minimum effective focal length and the maximum effective focal length according to the first to third modes, and preferably satisfies 10 mm < F < 32 mm.

[0362] [Mathematical Formula 56] TTL < 30mm

[0363] TTL (Total track length) refers to the distance from the center of the first surface (S1) of the first lens (101, 111, 121) to the surface of the image sensor (300) on the optical axis (OA). In mathematical expression 55, by setting the TTL to exceed 15 mm, a zoom magnification optical system can be provided. Preferably, 15 mm < TTL < 28 mm can be satisfied.

[0364] [Mathematical Formula 57] 3mm < EPD1 < EPD2 < EPD3 < 9mm

[0365] EPD1, EPD2, and EPD3 represent the range of the incident pupil of the optical system (1000) according to the first to third modes.

[0366] [Mathematical Formula 58] 8° < FOV3 < FOV2 < FOV1 < 45°

[0367] In mathematical expression 58, FOV (Field of view) means the angle of view (Degree) in the diagonal direction of the optical system (1000), FOV1 is the angle of view in the first mode, FOV2 is the angle of view in the second mode, and FOV3 represents the angle of view in the third mode, and can be set in the order of the angles of wide, middle, and tele modes depending on the operation mode. Preferably, 10° < FOV < 30° can be satisfied.

[0368] [Equation 59] 0.5 < TD / TTL < 1

[0369] TD is the optical axis distance from the center of the object-side surface of the first lens to the center of the sensor-side surface of the seventh lens. If the optical system satisfies Equation 59, the size of TD can be set relative to TTL.

[0370] [Equation 60] 0.5 < SD1 / TTL < 1

[0371] SD1 is the optical axis distance from the aperture position to the surface of the image sensor in the first mode (Wide mode). When the optical system satisfies Equation 60, the amount of light passing between the lenses can be controlled by setting the aperture position.

[0372] [Mathematical Formula 61] 10mm < SD1 < SD2 < SD3 < 25mm

[0373] SD2 is the optical axis distance from the position of the aperture to the surface of the image sensor in the second mode (Middle mode). SD3 is the optical axis distance from the position of the aperture to the surface of the image sensor in the third mode (Tele mode). When the optical system satisfies Equation 61, the amount of light passing between the lenses can be controlled by the aperture whose position varies depending on each mode.

[0374] [Equation 62] 1 < SD3 / SD1 < 2

[0375] If the optical system satisfies mathematical expression 62, the range according to the maximum distance change of the aperture can be set, thereby controlling the amount of light from wide mode to tele mode.

[0376] [Equation 64] 10 < TD / BFL

[0377] When the optical system satisfies Equation 64, the optical axis distance (BFL) between the last lens and the image sensor can be set, and the TTL can be reduced. Preferably, 10 < TD / BFL < 20 can be satisfied.

[0378]

[0379] [Mathematical Formula 65] 0.8mm < BFL < 3mm

[0380] When the optical system satisfies mathematical equation 65, the optical axis distance (BFL) between the last lens and the image sensor can be set narrowly, and the TTL can be reduced. In addition, the distance between the optical filter (500) and the image sensor (300) can be reduced. Preferably, 1 m < BFL < 3 mm can be satisfied.

[0381] [Equation 66] Md3_Fno ≤ 5

[0382] Md3_Fno is the F-number of the optical system in the third mode. If the optical system satisfies mathematical expression 66, it can provide a bright optical system.

[0383] [Equation 67] 0.55 < CA7x / CA7y < 0.9

[0384] CA7y is the average of the effective lengths of the object-side surface and the sensor-side surface in the second direction (Y) of the seventh lens (107, 117, 127), and CA7x is the average of the effective lengths of the object-side surface and the sensor-side surface in the first direction (X) of the first lens (107, 117, 127). When this mathematical expression 67 is satisfied, the length of the seventh lens having the maximum effective length in the first direction within the lens unit (100, 100A, 100B) can be lowered, thereby providing a slim optical system and camera module in the first direction.

[0385] [Equation 67-1] 0.55 < CA1x / CA1y < 0.9

[0386] CA1y is the average of the effective lengths of the object-side surface and the sensor-side surface in the second direction (Y) of the first lens (101, 111, 121), and CA1x is the average of the effective lengths of the object-side surface and the sensor-side surface in the first direction (X) of the first lens (101, 111, 121). When this mathematical expression 67 is satisfied, the length of the first lens in the first direction can be reduced, thereby providing a slim optical system and camera module in the first direction.

[0387] [Mathematical Formula 68] (CA72x / CA72y) ≤ CA71x / CA71y)

[0388] CA71x, CA71y are the effective lengths of the object-side surfaces of the seventh lens (107, 117, 127) in the first and second directions (X, Y), and CA72x, CA72y are the effective lengths of the sensor-side surfaces of the seventh lens (107, 117, 127) in the first and second directions (X, Y). When this mathematical expression 70 is satisfied, the length or area of ​​the object-side surface of the seventh lens can be set to be equal to or greater than the length or area of ​​the sensor-side surface.

[0389] [Equation 69]

[0390]

[0391] In mathematical expression 69, Z may represent Sag, which is the distance in the direction of the optical axis from any position on the aspherical surface to the vertex of the aspherical surface. In addition, Y may represent the distance in the direction perpendicular to the optical axis from any position on the aspherical surface to the optical axis. In addition, c may represent the curvature of the lens, and K may represent the conic constant. In addition, A, B, C, D, E, and F may represent aspheric constants from the 4th to the 14th order.

[0392]

[0393] The optical system (1000) according to the embodiment can satisfy at least one of the above-described mathematical expressions 1 to 68. Accordingly, the optical system (1000) and the camera module can have improved optical characteristics. Specifically, since the optical system (1000) satisfies at least one or two or more mathematical expressions of the above-described mathematical expressions 1 to 68, it can effectively correct optical characteristic degradation such as chromatic aberration, vignetting, diffraction effect, and deterioration of image quality in the peripheral area caused by movement of the lens group. In addition, the optical system (1000) according to the embodiment can significantly reduce the movement distance of the lens group and provide an autofocus (AF) function for various magnifications with excellent power consumption characteristics.

[0394] The optical system (1000) according to the embodiment can have improved assembly properties and a mechanically stable shape by satisfying at least one or more of the above mathematical expressions 1 to 68, and can be provided with a slim structure, so that the optical system (1000) and the camera module including the same can have a compact structure.

[0395]

[0396] Tables 7 and 8 are results for mathematical expressions 1 to 68 described above in the optical system (1000) of the embodiment. Referring to Table 7, it can be seen that the optical system (1000) satisfies at least one, two or more, or three or more of mathematical expressions 1 to 34. In detail, it can be seen that the optical system (1000) according to the embodiment satisfies all of mathematical expressions 1 to 34. Accordingly, the optical system (1000) can have good optical performance and excellent optical characteristics at the center and periphery of the field of view (FOV).

[0397] Mathematical expression Example 1 Example 2 Example 3 1nLG2 > 122220.75 < CA1 / CA7 < 0.980.8570.8490.8430 < CT1 / CT3 < 10.4550.4410.43140 < CT1 / CT4 < 10.4410.5620.5465L1R1*L2R1 < 0SatisfiedSatisfiedSatisfied6FLG1 < 0-24.790-23.85-25.1570 < CRA < 20SatisfiedSatisfiedSatisfied8(TTL / DLG1) > 3.58.9289.2238.26792 < TTL / EPD3 < 74.1034.1034.103102 < CT_Max / CT_Min < 64.5404.6354.377111< CA_Max / CA_Min <31.6461.6661.699120.3 < ΣCG / TTL < 0.80.4830.50.486130.25 < DLG1 / DLG2 < 0.80.5470.5830.635140.5 < DLG2 / DLG3 < 21.3521.1961.214150 < CG1 / TTL < 0.20.0430.0390.052162 < TTL / (DLG2+DLG3) < 52.8082.9292.881720 < |Vd2 - Vd3| <7031.80031.831.81815 < |Vd6 - Vd7| < 6036.50030.336.5191.6 < Nd11.6801.681.68200.5 < L1R1 / L2R2 < 1.51.0901.1471.029211 < L1R1 / L3R1 < 3.51.9471.9622.333221 < L2R2 / L3R1 < 31.7861.712.26823-0.8 < L1R1 / L7R2 < -0.3-0.515-0.714-0.389240 < Md12_mLG2 / TTL < 0.50.1190.120.119250 < Md23_mLG2 / TTL < 0.50.0980.0980.098260.3 < Md12_mLG2 / DLG2 < 10.5820.6430.624270.3 < Md23_mLG3 / DLG3 < 0.90.6300.6020.6280 < Md23_mLG3 / TTL < 0.50.0950.0940.094291 < Md23_mLG3 / DLG4 < 31.6901.8661.469301< Md1 (DG12 / DG23) < 52.8902.5112.831310.2< Md3 (DG12 / DG23) < 0.90.5640.4620.506322 < Md_CG_Max / Md_CG_Min < 83.6313.6623.528331 < Max_mMd13 < 74.8504.854.83345 < TTL / Max_mLG2 < 5.64.6024.6024.621.

[0398]

[0399] Referring to Table 8, it can be seen that the optical system (1000) satisfies at least one, two or more, or three or more of mathematical expressions 35 to 68. In detail, it can be seen that the optical system (1000) according to the embodiment satisfies all of the mathematical expressions 35 to 68. Accordingly, the optical system (1000) can have good optical performance and excellent optical characteristics at the center and periphery of the field of view (FOV).

[0400] Mathematical Formula Example 1 Example 2 Example 3 360.5 ≤ Md3_DG1 20.9 300.9 0.86 37 LG1_Vd2 < 35 - 6.2 20 - 6.2 8 - 6.1 9 38 LG3_Vd1 < 35 19.2 0 19.2 19.2 39 LG4_Nd > 1.6 1.6 8 1.8 11.6 8 4 0 20 < Aver_Vd < 5 0 30.9 14 31.8 30.9 14 4 1 1.5 < Aver_Nd < 1.8 1.6 3 0 1.6 4 9 1.6 3 4 22 < │ FLG1 / FLG2 │ < 43.6 19 3.4 1 2 3.6 2 4 4 31 < FMd3 / FMd1 < 31.9961.9961.764442 < FMd2 / EPD2 < 63.8213.8214.5451 < FMd1 / EPD1 < 42.8172.8172.81746FMd1 < FMd2 < FMd3SatisfiedSatisfiedSatisfied470.8 < TTL / FMd2 < 21.1781.1781481 < TTL / FMd1 < 31.7641.7641.764491 < CA_Max / ImgH < 32.3292.352.379505 < TTL / ImgH < 127.9717.9717.971510 <BFL / ImgH < 10.5360.5360.536522 < FMd1 / ImgH < 64.5184.5184.518536 < FMd3 / ImgH < 129.0189.0187.971542 < ImgH2.8002.82.85510 < F < 40만족만족만족56TTL < 3022.32022.3222.32573 < EPD1 < EPD2 <EPD3 < 9만족만족만족588 < FOV3 <FOV2 < FOV1 < 45만족만족만족590.5 < TD / TTL < 10.9330.9330.933600.5 < SD1 / TTL < 10.6020.6020.6026110 < SD1 < SD2 < SD3 < 25만족만족만족621 < SD3 / SD1 < 21.3861.3861.386630 < BFL / TTL < 0.50.0670.0670.0676410 < TD / BFL13.88013.88713.88650.8 < BFL < 31.5001.51.566Md3_Fno ≤ 54.6004.64.6670.55 < CA7x / CA7y < 0.9 Satisfied Satisfied Satisfied 68 (CA72x / CA72y) ≤ CA71x / CA71y) Satisfied Satisfied Satisfied.

[0401]

[0402] Referring to FIG. 29, a camera module includes an optical system (1000) disclosed above, and the optical system (1000) may include a reflective member (400) facing a subject or object, a lens unit (100, 100A, 100B) having a plurality of lens groups (LG1-LG4), and an image sensor (300). The camera module may include a first driving member (DM1) that drives a second lens group (LG2), and a second driving member (DM2) that drives a third lens group (LG3). The reflective member (400) may be disposed on a path of light reflected on the subject. The reflective member (400) may be disposed closer to the subject than the lens unit (100, 100A, 100B). That is, the reflective member (400), the lens unit (100, 100A, 100B) and the image sensor (300) can be arranged in the order from the subject side to the upper side.

[0403] The above reflective member (400) can change the path of light incident from the outside. The reflective member (400) can include a right-angle prism. When the reflective member (400) includes a right-angle prism, the reflective member (400) can reflect the path of the second optical axis direction (OA2) incident on the camera module (1000) at a 90-degree angle and change it to the first optical axis direction (OA2). The reflective member (400) can be rotated or tilted to adjust the path of light reflected on the subject. For example, the reflective member (400) can reflect light incident on the reflective member (400) in the second direction (OA2) and change the path of the light to the optical axis direction (OA1) in which the plurality of lenses of the lens units (100, 100A, 100B) are arranged.

[0404] When the above camera module includes the reflective member (400), it can be applied to a folded camera that can reduce the thickness of the camera module. The camera module is arranged parallel to the surface of the mobile terminal and can change light incident in a vertical second optical axis direction (OA2) into a first optical axis direction (OA1) that is parallel to the surface of the mobile terminal. Accordingly, the camera module (1000) including the lens unit (100, 100A, 100B) can have a low height in a direction perpendicular to the surface of the mobile terminal, and thus can have a thinner thickness within the mobile terminal, and thus the thickness of the device can also be thinner.

[0405]

[0406] The third driving member (410) may be connected to the reflective member (400). The third driving member (410) may include at least one actuator. For example, the third driving member (410) may include at least one of a voice coil motor (VCM), a piezoelectric device, a shape memory alloy, and a MEMS device as an actuator. The third driving member (410) may move the reflective member (400) using the driving force of the actuator. For example, the third driving member (410) may tilt-control the reflective member (400) along a first axis or a second axis. In detail, the third driving member (410) may tilt-control the reflective member (400) along a second direction (Z-axis direction) as a rotation axis. In addition, the third driving member (410) can tilt-control the reflection member (400) about the rotation axis in the third direction (OA1, Z-axis direction). Accordingly, the camera module can compensate for shaking.

[0407] It includes a sensing unit (not shown) that detects the shaking of the camera module, and the sensing unit can detect rotation and position changes applied to the camera module. The sensing unit may include at least one of a sensor that detects a change in angular velocity, for example, a gyro sensor, and an acceleration sensor that detects a change in acceleration.

[0408] The above camera module can control the movement of the reflective member (400) by a control signal. In detail, when shaking occurs in the camera module, information about the shaking, such as the degree of rotation and position change of the sensors, can be detected, and compensation for the shaking can be performed. Accordingly, the camera module according to the embodiment can operate in wide mode, middle mode, and tele mode by the first and second driving members (DM1, DM2), and when photographing a subject, shaking due to rotation and shaking due to position change can be effectively compensated. Accordingly, the camera module can have improved optical characteristics.

[0409]

[0410] FIG. 30 is a drawing illustrating a camera module disclosed in an embodiment applied to a mobile terminal. Referring to FIG. 30, the mobile terminal (1) may include the camera module (10) disclosed in the embodiment on the rear side. As another example, the mobile terminal (1) may include the camera module disclosed in the embodiment on the front side. The camera module (10) may include an image capturing function. In addition, the camera module (10) may include at least one of an auto focus, a zoom function, and an OIS function. The camera module (10) may process still images or video frames obtained by the image sensor (300) in a shooting mode or a video call mode. The processed image frames may be displayed on a display unit (not shown) of the mobile terminal (1) and stored in a memory (not shown). In addition, although not shown in the drawing, the camera module may be further arranged on the front side of the mobile terminal (1). For example, the camera module (10) may include a first camera module (10A) and a second camera module (10B). At this time, at least one of the first camera module (10A) and the second camera module (10B) may include the optical system (1000) described above. Accordingly, the camera module (10) may have a slim structure and may photograph a subject at various magnifications. The mobile terminal (1) may further include an auto-focus device (31). The auto-focus device (31) may include an auto-focus function using a laser. The auto-focus device (31) may be mainly used in conditions where the auto-focus function using the image of the camera module (10) is degraded, for example, in a close range of 10 m or less or in a dark environment. The auto-focus device (31) may include a light-emitting unit including a vertical cavity surface-emitting laser (VCSEL) semiconductor element, and a light-receiving unit that converts light energy into electrical energy, such as a photodiode.

[0411] The mobile terminal (1) may further include a flash module (33). The flash module (33) may include a light-emitting element that emits light therein. The flash module (33) may emit light in the visible light wavelength band. For example, the flash module (33) may emit white light or light of a color similar to white. However, the embodiment is not limited thereto, and the flash module (33) may emit light of various colors. The flash module (33) may be operated by the camera operation of the mobile terminal or by the user's control.

[0412] The features, structures, effects, etc. described in the embodiments above are included in at least one embodiment of the present invention, and are not necessarily limited to just one embodiment. Furthermore, the features, structures, effects, etc. illustrated in each embodiment can be combined or modified and implemented in other embodiments by a person having ordinary skill in the art to which the embodiments pertain. Therefore, the contents related to such combinations and modifications should be interpreted as being included in the scope of the present invention. Although the embodiments have been described above, these are merely examples and do not limit the present invention. Those having ordinary skill in the art to which the present invention pertains will appreciate that various modifications and applications not illustrated above are possible without departing from the essential characteristics of the embodiments. For example, each component specifically shown in the embodiments can be modified and implemented. In addition, differences related to such modifications and applications should be interpreted as being included in the scope of the present invention defined in the appended claims.

Claims

1. A first lens group adjacent to the object and having negative (-) power; A second lens group arranged on the sensor side of the first lens group; A third lens group arranged on the sensor side of the second lens group; and A fourth lens group is disposed on the sensor side of the third lens group and includes a fourth lens group having negative (-) power, The second and third lens groups move along the optical axes of the lenses in the first to fourth lens groups to perform a zoom magnification from wide mode to tele mode, The number of lenses in at least one of the second and third lens groups is greater than the number of lenses in the fourth lens group, The optical axis distance of the second lens group is greater than the optical axis distance of the first lens group, A camera module wherein the fourth lens group includes a lens having the longest effective length among the effective lengths of the lenses in the first to fourth lens groups.

2. In paragraph 1, The maximum movement distance of the second or third lens group according to the above zoom ratio is Max_mMd13, Mathematical formula: 1mm < Max_mMd13 < 7mm Camera module that satisfies .

3. In paragraph 1, The minimum optical axis distance between the first lens group and the second lens group according to the above tele mode is Md3_DG12, Mathematical formula: 0.5mm ≤ Md3_DG12 < 1.5mm Camera module that satisfies .

4. In any one of paragraphs 1 to 3, A camera module in which the lens closest to the object in the first lens group has positive power and has a convex meniscus shape toward the object.

5. In paragraph 4, A camera module in which the lens closest to the image sensor in the seventh lens group has positive power and has a biconvex shape.

6. In paragraph 5, A camera module wherein the lens closest to the image sensor is a lens having the maximum effective length among the first to fourth lens groups.

7. In any one of paragraphs 1 to 4, The above seventh lens is a camera module made of glass.

8. In any one of paragraphs 1 to 4, A camera module wherein the first lens has a spherical shape and is made of glass.

9. In any one of paragraphs 1 to 4, The number of lenses in the first lens group is the same as the number of lenses in the second and third lens groups, A camera module wherein each of the first to third lens groups includes lenses having powers of opposite signs.

10. In paragraph 5, It includes a reflective member arranged on the object side of the first lens group, A camera module in which the lens closest to the image sensor has a shape in which the effective lengths in the first and second directions perpendicular to the optical axis are different.

11. A first lens group having first and second lenses sequentially arranged toward the image sensor on the object side and having negative power; A second lens group arranged on the sensor side of the first lens group; A third lens group arranged on the sensor side of the second lens group; and A fourth lens group having a last lens positioned between the third lens group and the image sensor and having positive power, The second and third lens groups move along the optical axes of the lenses in the first to fourth lens groups to perform a zoom magnification from wide mode to tele mode, The object-side surface of the above first lens has a convex shape on the optical axis, The absolute value of the radius of curvature of the sensor-side surface of the first lens is greater than the radius of curvature of the object-side surface of the first lens, The first and fourth lens groups are fixed in position on the optical axis, The number of lenses in the second and third lens groups is smaller than the number of lenses in the fourth lens group, Among the optical axis distances of the first to fourth lens groups, the optical axis distance of the second lens group is the longest, The optical axis distance of the first to fourth lens groups is the distance in the optical axis direction from the object-side lens to the sensor-side lens arranged in each lens group. A camera module wherein the effective length of the first lens is smaller than the effective length of the last lens and larger than the effective lengths of the lenses in the second and third lens groups.

12. In paragraph 11, The refractive index of the first lens is Nd1, and the Abbe number is Vd1. The refractive index of the last lens above is Ndn, and the Abbe number is Vdn. Mathematical formula: Nd1*Vd1 < 50 Ndn*Vdn < 50 Camera module that satisfies .

13. In paragraph 11, It includes a reflective member arranged on the object side of the first lens, A camera module wherein at least one of the first lens and the last lens has a shape in which the effective lengths in the first and second directions perpendicular to the optical axis are different.

Images