Optical system and camera module including the optical system

Abstract

The zoom optical system according to an embodiment of the present invention includes a first lens group, a second lens group, a third lens group, and a fourth lens group arranged sequentially from the object side to the image side, wherein each of the first to fourth lens groups includes two lenses, the second and third lens groups are movable, and the effective focal length (EFL) is defined by the following mathematical expression: where EFL tele This refers to the effective focal length of a zoom optical system at its longest focal length, and H imageD It refers to half the diagonal length of the pixel area of ​​the image sensor.

Description

Technical Field

[0001] The embodiments relate to an optical system and a camera module including the optical system. Background Technology

[0002] As the performance of camera modules built into portable devices improves, these modules also need autofocus functionality.

[0003] To enable autofocus in the camera module of a portable terminal, magnification can be increased through digital processing during the conversion of external light into digital images or digital video. Therefore, zooming is limited to a predetermined magnification (such as 1x, 3x, or 5x), and as the magnification increases, resolution decreases and digital degradation occurs.

[0004] Meanwhile, to enable autofocus in camera modules of portable devices, techniques have been explored that adjust the distance between the lens and the image sensor by moving the lens. However, designing a movable optical system within the confined space of a portable device is not easy. Summary of the Invention

[0005] [Technical Issues]

[0006] The present invention aims to provide a zoom optical system and a camera module including the zoom optical system.

[0007] The purpose of the embodiments is not limited thereto, and will also include purposes or effects that can be identified from the configuration or embodiments, as will be described below.

[0008] [Technical Solution]

[0009] The zoom optical system according to an embodiment of the present invention includes a first lens group, a second lens group, a third lens group, and a fourth lens group arranged sequentially from the object side to the image side, wherein each of the first to fourth lens groups includes two lenses, the second and third lens groups are movable, and the effective focal length (EFL) in the telephoto range is defined by the following mathematical expression:

[0010]

[0011] Among them, EFL tele This refers to the effective focal length of a zoom optical system in the telephoto range, and H imageD It refers to half the diagonal length of the pixel area of ​​the image sensor.

[0012] The effective focal length (EFL) in a wide-angle lens can be defined by the following mathematical expression:

[0013]

[0014] Among them, EFL wide This refers to the effective focal length of a zoom optical system in a wide-angle field, and H imageD It refers to half the diagonal length of the pixel area of ​​the image sensor.

[0015] When zooming from wide-angle to telephoto, the movement of the second lens group can be defined by the following mathematical expression:

[0016]

[0017] The total track length (TTL) refers to the distance between the image sensor plane and the first plane of the zoom optical system, and STROKE2 refers to the travel distance of the second lens group.

[0018] When zooming from wide-angle to telephoto, the movement of the third lens group can be defined by the following mathematical expression:

[0019]

[0020] The total track length (TTL) refers to the distance between the image sensor plane and the first plane of the zoom optical system, and STROKE3 refers to the travel distance of the third lens group.

[0021] Each of the first lens group and the second lens group may include at least one glass lens.

[0022] At least one of the lenses arranged on the image side of the two lenses included in the first lens group or on the object side of the two lenses included in the second lens group may be a glass lens.

[0023] The two lenses included in the second lens group can have Abbe's numbers as defined by the following mathematical expression:

[0024] |ABBE3-ABBE4|>10

[0025] Wherein, ABBE3 refers to the Abbe number of the lens arranged on the object-side plane of the two lenses included in the second lens group, and ABBE4 refers to the Abbe number of the lens arranged on the image-side plane of the two lenses included in the second lens group.

[0026] At least one of the lenses included in the first to fourth lens groups may be a D-cut lens.

[0027] The maximum diameter of the multiple lenses included in the first to fourth lens groups, and the maximum diameter of the multiple lenses included in the second and third lens groups, can be defined by the following mathematical expressions:

[0028]

[0029] Among them, APER fix This can refer to the maximum diameter of the lenses included in the first and fourth lens groups, which are fixed groups, and APER. mov It can refer to the maximum diameter of the lenses included in the second and third lens groups, which are movable groups.

[0030] The lens arranged on the object side of the two lenses included in the first lens group can have positive refractive power, and the lens arranged on the image side of the two lenses included in the first lens group can have negative refractive power.

[0031] The zoom optical system may also include right-angle prisms arranged sequentially from the object side to the image side at the front end of the first lens group.

[0032] The zoom optical system according to an embodiment of the present invention includes a first lens group, a second lens group, a third lens group, and a fourth lens group arranged sequentially from the object side to the image side, wherein each of the first to fourth lens groups includes two lenses, the second and third lens groups are movable, and the effective focal length (EFL) in the wide-angle is defined by the following mathematical expression:

[0033]

[0034] Among them, EFL wide This refers to the effective focal length of a zoom optical system in a wide-angle field, and H imageD It refers to half the diagonal length of the pixel area of ​​the image sensor.

[0035] [Beneficial Effects]

[0036] According to embodiments of the present invention, an optical system capable of zooming at both high and low magnification, and a camera module including the optical system, can be obtained. The optical system according to embodiments of the present invention is capable of performing continuous zoom adjustment and maintaining high resolution even at high magnification. Attached Figure Description

[0037] Figure 1 A zoom optical system according to a first embodiment of the present invention is shown.

[0038] Figure 2a This is a wide-angle cross-sectional view of a zoom optical system according to a first embodiment of the present invention.

[0039] Figure 2b This is a cross-sectional view of the intermediate mode of the zoom optical system according to the first embodiment of the present invention.

[0040] Figure 2c This is a cross-sectional view of the telephoto lens of the zoom optical system according to the first embodiment of the present invention.

[0041] Figure 3a The graph is obtained by measuring the longitudinal spherical aberration, astigmatism curve, and distortion of light having wavelengths of 435 nm, 486 nm, 546 nm, 587 nm, and 656 nm in the wide-angle field of the optical system according to the first embodiment.

[0042] Figure 3b The graph is obtained by measuring the longitudinal spherical aberration, astigmatism curve, and distortion of light having wavelengths of 435 nm, 486 nm, 546 nm, 587 nm, and 656 nm in an intermediate mode of the optical system according to the first embodiment.

[0043] Figure 3c The graph is obtained by measuring the longitudinal spherical aberration, astigmatism curve, and distortion of light having wavelengths of 435 nm, 486 nm, 546 nm, 587 nm, and 656 nm in the telephoto lens of the optical system according to the first embodiment.

[0044] Figure 4a This is a diagram of the diffraction modulation transfer function (MTF) in the wide-angle view of the optical system according to the first embodiment.

[0045] Figure 4b It is a diffraction MTF pattern in the intermediate mode of the optical system according to the first embodiment.

[0046] Figure 4c It is a diffraction MTF pattern in the telephoto lens of the optical system according to the first embodiment.

[0047] Figure 5 The graph is obtained by measuring the relative illumination of the zoom optical system according to the first embodiment of the present invention.

[0048] Figure 6 A zoom optical system according to a second embodiment of the present invention is shown.

[0049] Figure 7a This is a cross-sectional view of the zoom optical system in the wide-angle direction according to a second embodiment of the present invention.

[0050] Figure 7b This is a cross-sectional view of the intermediate mode of the zoom optical system according to the second embodiment of the present invention.

[0051] Figure 7c This is a cross-sectional view of the telephoto lens of the zoom optical system according to the second embodiment of the present invention.

[0052] Figure 8a The graph is obtained by measuring the longitudinal spherical aberration, astigmatism curve, and distortion of light having wavelengths of 435 nm, 486 nm, 546 nm, 587 nm, and 656 nm in the wide-angle field of the optical system according to the second embodiment.

[0053] Figure 8b The graph is obtained by measuring the longitudinal spherical aberration, astigmatism curve, and distortion of light having wavelengths of 435 nm, 486 nm, 546 nm, 587 nm, and 656 nm in the intermediate mode of the optical system according to the second embodiment.

[0054] Figure 8c The graph is obtained by measuring the longitudinal spherical aberration, astigmatism curve, and distortion of light having wavelengths of 435 nm, 486 nm, 546 nm, 587 nm, and 656 nm in the telephoto lens of the optical system according to the second embodiment.

[0055] Figure 9a This is a diffraction MTF diagram in the wide-angle view of the optical system according to the second embodiment.

[0056] Figure 9b It is a diffraction MTF pattern in the intermediate mode of the optical system according to the second embodiment.

[0057] Figure 9c This is a diffraction MTF pattern in the telephoto lens of the optical system according to the second embodiment.

[0058] Figure 10 The graph is obtained by measuring the relative illumination of the zoom optical system according to the second embodiment of the present invention.

[0059] Figure 11 A portion of a portable terminal employing a camera module according to an embodiment of the present invention is shown. Detailed Implementation

[0060] In the following, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0061] However, the spirit of the invention is not limited to some of the described embodiments, but can be implemented in various different forms, and one or more components can be used by selective coupling and substitution without departing from the spirit of the invention.

[0062] Furthermore, the terms (including technical and scientific terms) used in the embodiments of the present invention can be interpreted as follows: unless explicitly and specifically defined, they are generally understood by those skilled in the art to which this invention pertains, and can be interpreted in the context of the relevant art, such as terms defined in dictionaries.

[0063] Furthermore, the terminology used in the embodiments of the present invention is for the purpose of describing the embodiments of the present invention and is not intended to limit the present invention.

[0064] In this specification, unless otherwise stated in the phrase, the singular form may also include the plural form, and when described as “at least one (or one or more) of A and B, C”, it may include one or more of all possible combinations of A, B and C.

[0065] Furthermore, when describing components of embodiments of the present invention, terms such as first, second, A, B, (a), and (b) may be used.

[0066] These terms are intended only to distinguish components from other components, and the nature, order, or sequence of the corresponding components are not limited by these terms.

[0067] Furthermore, when describing a component as “connected,” “coupled,” or “engaged” to another component, this can include cases where the component is not only directly connected, coupled, or engaged to another component, but also cases where the component is “connected,” “coupled,” or “engaged” to another component through other components inserted therein.

[0068] Furthermore, when described as forming or arranging "top (above) or bottom (below)" of each component, "top (above)" or "bottom (below)" includes not only the case where two components are in direct contact with each other, but also the case where one or more other components are formed or arranged between the two components. Additionally, when expressed as "top (above) or bottom (below)," this can also include not only the meaning of an upward direction relative to a component, but also the meaning of a downward direction relative to a component. Figure 1 A zoom optical system according to a first embodiment of the present invention is shown.

[0069] refer to Figure 1 According to a first embodiment of the present invention, the zoom optical system includes a first lens group 100, a second lens group 200, a third lens group 300, and a fourth lens group 400 arranged sequentially from the object side to the image side. A right-angle prism may also be arranged at the front end of the first lens group 100.

[0070] According to a first embodiment of the present invention, a first lens group 100 includes a plurality of lenses. The first lens group 100 may include at least two or more lenses. Since it may be difficult to correct the resolution at maximum magnification when the first lens group 100 includes a single lens, and the overall size of the zoom optical system may increase when the first lens group 100 includes three or more lenses, the first lens group 100 may preferably include two lenses 110 and 120.

[0071] The first lens group 100 is fixed to the image side. The first lens group 100 is fixed to the plane of the sensor 10. In other words, multiple lenses are fixed to the image side. When the first lens group 100 includes two lenses, the two lenses 110 and 120 can be fixed to the image side.

[0072] The second lens group 200 includes a plurality of lenses. The second lens group 200 may include at least two lenses. Since it may be difficult to correct the resolution at maximum magnification when the second lens group 200 includes a single lens, and the overall size of the zoom optical system may increase when the second lens group 200 includes three or more lenses, the second lens group 200 may preferably include two lenses 210 and 220.

[0073] The second lens group 200 is movable. Multiple lenses included in the second lens group 200 are movable together along the central axis of the lens. Two lenses 210 and 220 included in the second lens group 200 are movable together along the central axis of the lens. When the second lens group 200 includes three or more lenses, the size and weight of the second lens group 200 may increase, and the driving force may increase with movement. Therefore, the second lens group 200 preferably includes two lenses 210 and 220. The focal length can be continuously adjusted according to the movement of the second lens group 200. The magnification can be continuously adjusted according to the movement of the second lens group 200. Therefore, the second lens group 200 can be used as a zoom group.

[0074] The third lens group 300 includes multiple lenses. The third lens group 300 and the first lens group 300 may each include at least two lenses. Since it may be difficult to correct the resolution at maximum magnification when the third lens group 300 includes a single lens, and the overall size of the zoom optical system may increase when the third lens group 300 includes three or more lenses, the third lens group 300 may preferably include two lenses 310 and 320.

[0075] The third lens group 300 is movable. Multiple lenses included in the third lens group 300 are movable together along the central axis of the lens. Two lenses 310 and 320 included in the third lens group 300 are movable together along the central axis of the lens. When the third lens group 300 includes three or more lenses, the size and weight of the third lens group 300 may increase, and the driving force may increase with movement. Therefore, the third lens group 300 may include two lenses 310 and 320. The focus can be adjusted according to the movement of the third lens group 300. The third lens group 300 can be used as a focusing group.

[0076] The fourth lens group 400 includes multiple lenses. The fourth lens group 400 may include at least two lenses. Since it may be difficult to correct the resolution at maximum magnification when the fourth lens group 400 includes a single lens, and the overall size of the zoom optical system may increase when the fourth lens group 400 includes three or more lenses, the fourth lens group 400 may preferably include two lenses 410 and 420.

[0077] The fourth lens group 400 is fixed to the image side. The fourth lens group 400 is fixed to the plane of the sensor 10. In other words, multiple lenses are fixed to the image side. When the fourth lens group 400 includes two lenses, the two lenses 410 and 420 can be fixed to the image side.

[0078] According to a first embodiment of the present invention, the filter 20 and the image sensor 10 can be arranged sequentially at the rear end of the fourth lens group 400. In this case, the filter 20 can be an infrared (IR) filter. Therefore, the filter 20 can block near-infrared light (e.g., light with wavelengths from 700 nm to 1100 nm) from the light incident on the camera module. Furthermore, the image sensor 10 can be connected to a printed circuit board via a wire.

[0079] Filter 20 may also include an anti-foreign object filter and an IR filter arranged sequentially from the object side to the image side. When filter 20 includes an anti-foreign object filter, it can prevent foreign objects generated during the movement of the third lens group 300 from being introduced into the IR filter or the image sensor 10.

[0080] The magnification of the zoom optical system can vary depending on the movement of the second lens group 200 and the third lens group 300. For example, the magnification of the zoom optical system can continuously increase or decrease between 3x and 7.5x depending on the movement of the second lens group 200 and the third lens group 300. According to the first embodiment, the zoom optical system can have a magnification of 3x in the wide-angle and 7.5x in the telephoto. Furthermore, when the magnification increases or decreases continuously, it may mean that the magnification does not increase or decrease intermittently numerically, but rather linearly.

[0081] Each of the second lens group 200 and the third lens group 300 can move independently. For example, when the zoom optical system moves from wide-angle to telephoto, the distance between the second lens group 200 and the third lens group 300 can increase from the starting point of the movement (wide-angle) to a predetermined point, and then gradually decrease from the predetermined point to the ending point of the movement (telephoto).

[0082] The effective focal length (EFL) of the zoom optical system according to a first embodiment of the present invention will be described.

[0083] In a zoom optical system, the effective focal length at the telephoto end can be represented by the following mathematical expression 1:

[0084] [Mathematical Expression 1]

[0085]

[0086] Among them, EFL tele This refers to the effective focal length of a zoom optical system in the telephoto range, and H imageD This refers to half the diagonal length of the pixel area of ​​an image sensor. The unit can be [mm]. The pixel area of ​​an image sensor can refer to the area of ​​pixels arranged in the image sensor that receive light. The pixel area of ​​an image sensor can also exclude the circuit area where the received light is converted into an electrical signal, or the area of ​​the housing, etc., from the entire area of ​​the image sensor.

[0087] In a zoom optical system, the effective focal length in the wide-angle range can be represented by the following mathematical expression 2:

[0088] [Mathematical Expression 2]

[0089]

[0090] Among them, EFL wide This refers to the effective focal length of a zoom optical system in the wide-angle range, and H imageD It refers to half the diagonal length of the pixel area of ​​the image sensor.

[0091] The travel distance of a zoom optical system according to a first embodiment of the present invention will be described. The travel distance can refer to the distance the lens group can be moved by the drive unit.

[0092] The travel distance of the second lens group 200 can be represented by the following mathematical expression 3:

[0093] [Mathematical Expression 3]

[0094]

[0095] The total track length (TTL) can refer to the distance from the image sensor plane to the first plane of the zoom optical system. For example, TTL can refer to the distance from the plane closest to the object side of the first lens group 100 to the upper plane of the image sensor 10 on which light is incident. In this specification, TTL can be used interchangeably with the total length distance. STROKE2 can refer to the travel distance of the second lens group 200. The unit can be [mm].

[0096] The travel distance of the third lens group 300 can be represented by the following mathematical expression 4:

[0097] [Mathematical Expression 4]

[0098]

[0099] Here, TTL can refer to the distance from the image sensor plane to the first plane of the zoom optical system. STROKE3 can refer to the travel distance of the third lens group 300. The unit can be [mm].

[0100] When the travel distance is large, it becomes difficult to install the drive unit in a portable terminal because the size of the drive unit, configured to move the second lens group 200 and the third lens group 300, increases. However, compared to TTL, by implementing the travel distance as 1 / 4 to 1 / 3, the size of the drive unit can be reduced, thereby miniaturizing the camera module.

[0101] The Abbe number of a zoom optical system according to a first embodiment of the present invention will be described. The Abbe number can refer to a numerical value of a property related to the light dispersion of a lens.

[0102] Multiple lenses included in the second lens group 200 can have different Abbe numbers. When the second lens group 200 includes two lenses, the Abbe numbers of the two lenses included in the second lens group 200 can be represented by the following mathematical expression 5:

[0103] [Mathematical Expression 5]

[0104] |ABBE3-ABBE4|>10

[0105] Wherein, ABBE3 can refer to the Abbe number of the lens arranged on the object-side plane of the two lenses included in the second lens group 200, and ABBE4 can refer to the Abbe number of the lens arranged on the image-side plane of the two lenses included in the second lens group 200. According to the first embodiment, ABBE3 can refer to the Abbe number of the third lens 210, and ABBE4 can refer to the Abbe number of the fourth lens 220.

[0106] According to a first embodiment of the present invention, the zoom optical system can remove chromatic aberration by arranging two lenses having Abbe numbers that differ from each other by a certain value or greater in each of the second lens group 200 and the fourth lens group 400.

[0107] The aperture of the lens of the zoom optical system according to the first embodiment of the present invention will be described.

[0108] According to a first embodiment of the present invention, the apertures of the second lens group 200 and the third lens group 300 can be smaller than the apertures of the first lens group 100 and the fourth lens group 400. This can be expressed by the following mathematical expression 6:

[0109] [Mathematical Expression 6]

[0110]

[0111] Among them, APER fix This can refer to the maximum diameter of the lenses included in the first lens group 100 and the fourth lens group 400, which are fixed groups, and APER mov This can refer to the maximum diameter of the lenses included in the second lens group 200 and the third lens group 300, which are movable groups. For example, when the diameter of the first lens 110 is the largest among the lenses included in the first lens group 100 and the fourth lens group 400, which are fixed groups, APER fix This can refer to the diameter of the first lens 110. When the diameter of the third lens 210 is the largest among the lenses included in the second lens group 200 and the third lens group 300, which are movable groups, APER... mov It could refer to the diameter of the third lens 210.

[0112] By making the apertures of the second lens group 200 and the third lens group 300 smaller than those of the first lens group 100 and the fourth lens group 400, the weight of the second lens group 200 and the third lens group 300 can be reduced. Therefore, when the second lens group 200 and the third lens group 300 (as a movable group) move, power consumption can be reduced.

[0113] According to a first embodiment of the present invention, the plurality of lenses 110, 120, 210, 220, 310, 320, 410, and 420 included in the first lens group 100 to the fourth lens group 400 may be lenses employing D-cut technology. The plurality of lenses 110, 120, 210, 220, 310, 320, 410, and 420 included in the first lens group 100 to the fourth lens group 400 may be D-cut lenses having partially cut upper and lower portions. In this case, the upper and lower portions of the plurality of lenses 110, 120, 210, 220, 310, 320, 410, and 420 may have partially cut ribs and an effective diameter, or only have cut ribs without cutting the effective diameter. According to one embodiment, the second lens group 200 and the third lens group may include lenses whose value is 1 obtained by dividing the major axis length of the effective diameter by the minor axis length of the effective diameter. In other words, the major axis of the effective diameter can be the same as the minor axis. For example, the upper and lower portions of the fifth lens 220, the sixth lens 310, and the seventh lens 320 can have only cut ribs without cutting the effective diameter. Circular lenses have the problem that the lens volume increases with vertical height, but as in the first embodiment of the invention, the vertical height can be reduced by applying D-cut technology to the upper and lower portions of multiple lenses 110, 120, 210, 220, 310, 320, 410, and 420, thereby reducing the lens volume.

[0114] According to a first embodiment of the present invention, the first lens group 100 may include a plurality of lenses with different refractive powers. The first lens 110 and the second lens 120 included in the first lens group 100 may have different refractive powers. According to the first embodiment, the first lens 110 may have a positive (+) refractive power, and the second lens 120 may have a negative (-) refractive power.

[0115] According to a first embodiment of the present invention, each of the first lens group 100 to the fourth lens group 400 may include a plastic lens. In this case, each of the first lens group 100 and the second lens group 200 may include a glass lens. At least one of the plurality of lenses included in the first lens group 100 and the second lens group 200 may be a glass lens.

[0116] According to one embodiment, the second lens 120 disposed on the image side of the lens included in the first lens group 100 may be a glass lens. According to another embodiment, the third lens 210 disposed on the object side of the lens included in the second lens group 200 may be a glass lens. According to yet another embodiment, both the second lens 120 disposed on the image side of the lens included in the first lens group 100 and the third lens 210 disposed on the object side of the lens included in the second lens group 200 may be glass lenses.

[0117] Figure 2a This is a wide-angle cross-sectional view of a zoom optical system according to a first embodiment of the present invention. Figure 2b This is a cross-sectional view of the intermediate mode of the zoom optical system according to the first embodiment of the present invention, and Figure 2c This is a cross-sectional view of the telephoto lens of the zoom optical system according to the first embodiment of the present invention.

[0118] Tables 1 and 2 below show the optical characteristics of the lenses included in the zoom optical system according to the first embodiment of the present invention, and Tables 3 and 4 show the conic constants and aspherical coefficients of the lenses included in the zoom optical system according to the first embodiment of the present invention.

[0119] Table 1

[0120]

[0121] Table 2

[0122]

[0123] Table 3

[0124]

[0125]

[0126] Table 4

[0127] Lens plane number E F G H J 112 2.68E-07 -6.35E-08 1.05E-09 6.04E-11 2.37E-11 114 -1.32E-07 -1.10E-07 6.82E-11 2.49E-09 -1.60E-10 122 -2.41E-06 -2.89E-07 2.13E-08 1.74E-08 -1.79E-09 124 -4.01E-06 1.13E-06 -2.61E-08 -4.82E-09 -2.43E-13 212 1.96E-06 -5.36E-07 -2.64E-07 -5.32E-08 3.22E-10 214 -2.79E-06 -2.63E-06 -5.56E-08 6.80E-08 -5.90E-10 222 1.57E-07 7.93E-07 2.93E-07 -2.40E-09 5.24E-11 224 7.06E-05 -6.50E-06 -7.83E-09 -1.77E-09 -6.11E-10 312 4.35E-06 1.04E-07 2.37E-08 -6.60E-09 -8.75E-19 314 -2.75E-06 -1.82E-06 -2.51E-16 -1.48E-17 -9.33E-19 322 2.82E-05 -3.26E-15 -2.26E-16 -1.46E-17 -9.32E-19 324 -4.97E-05 -4.89E-15 -2.35E-16 -1.46E-17 -9.32E-19 412 2.20E-05 -8.22E-07 -1.72E-08 -1.52E-08 -6.04E-19 414 -1.29E-05 9.18E-06 -9.15E-07 -1.55E-08 -1.07E-18 422 6.58E-06 -1.18E-06 4.42E-07 -5.18E-08 9.06E-10 424 -1.26E-05 1.86E-06 5.90E-08 -1.05E-08 2.68E-10

[0128] refer to Figures 2a to 2cAs shown in Tables 1 to 4, the zoom optical system includes a first lens group 100, a second lens group 200, a third lens group 300, and a fourth lens group 400 arranged sequentially from the object side to the image side. The first lens group 100 includes a first lens 110 and a second lens 120 arranged sequentially from the object side to the image side. The second lens group 200 includes a third lens 210 and a fourth lens 220 arranged sequentially from the object side to the image side. The third lens group 300 includes a fifth lens 310 and a sixth lens 320 arranged sequentially from the object side to the image side. The fourth lens group 400 includes a seventh lens 410 and an eighth lens 420 arranged sequentially from the object side to the image side.

[0129] In Table 1, the thickness (mm) represents the distance from each lens plane to the next lens plane.

[0130] For example, the thickness described on the object-side plane 112 of the first lens 110 represents the distance from the object-side plane 112 of the first lens 110 to the image-side plane 114. Specifically, the thickness described on the object-side plane 112 of the first lens 110 represents the distance between the center of curvature of the object-side plane 112 and the center of curvature of the image-side plane 114 in the first lens 110.

[0131] The thickness described on the image-side plane 114 of the first lens 110 represents the distance from the image-side plane 114 of the first lens 110 to the object-side plane 122 of the second lens 120. Specifically, the thickness described on the image-side plane 114 of the first lens 110 represents the distance between the center of curvature of the image-side plane 114 of the first lens 110 and the center of curvature of the object-side plane 122 of the second lens 120.

[0132] The thickness described on the image-side plane 124 of the second lens 120 represents the distance from the image-side plane 124 of the second lens 120 to the object-side plane 212 of the third lens 210. Specifically, the thickness described on the image-side plane 124 of the second lens 120 represents the distance between the center of curvature of the image-side plane 124 of the second lens 120 and the center of curvature of the object-side plane 212 of the third lens 210.

[0133] At this time, because the second lens group 200 moves during the zoom process from wide-angle to telephoto, the thickness described on the image side plane 124 of the second lens 120 can vary. The thickness described on the image side plane 124 of the second lens 120 can have a value between the shortest and longest distance. Referring to Table 1, the thickness described on the image side plane 124 of the second lens 120 can have the longest distance (4.5682758592) in wide-angle mode. The thickness described on the image side plane 124 of the second lens 120 can have a value between the shortest and longest distance (2.407378747) in intermediate mode. The thickness described on the image side plane 124 of the second lens 120 can have the shortest distance (0.2141379309) in telephoto mode. The thickness described on the image side plane 224 of the fourth lens 220 is also the same as the thickness described on the image side plane 324 of the sixth lens 320.

[0134] Referring to Table 1, it can be seen that the Abbe number difference between the third lens 210 and the fourth lens 220, which are included in the second lens group 200, is 10 or greater. Specifically, it can be seen that since the Abbe number of the third lens 210 is 56.11613 and the Abbe number of the fourth lens 220 is 19.24252, the Abbe number difference between the two lenses is approximately 37, and therefore the difference is 10 or greater.

[0135] Referring to Table 1, it can be seen that any one of the first lens 110 to the fourth lens 220 included in the first lens group 100 and the second lens group 200 is a glass lens. Specifically, it can be seen that the first lens 110, the third lens 210 and the fourth lens 220 are plastic lenses, and the second lens 120 is a glass lens.

[0136] Referring to Table 2, each plane of the first lens 110 to the eighth lens 420 can be convex or concave.

[0137] The first lens 110 can be a lens that bulges from the object-side plane 112 toward the object side. The first lens 110 can also be a lens that is recessed from the image-side plane 114 toward the object side. The second lens 120 can be a lens that bulges from the object-side plane 122 toward the object side. The second lens 120 can also be a lens that bulges from the image-side plane 124 toward the object side.

[0138] The third lens 210 can be a lens that bulges from the object-side plane 212 towards the object side. The third lens 210 can also be a lens that is recessed from the image-side plane 214 towards the object side. The fourth lens 220 can be a lens that is recessed from the object-side plane 222 towards the object side. The fourth lens 220 can also be a lens that is recessed from the image-side plane 224 towards the object side.

[0139] The fifth lens 310 can be a lens that bulges towards the object side from the object side plane 312. The fifth lens 310 can also be a lens that bulges towards the object side from the image side plane 314. The sixth lens 320 can be a lens that bulges towards the object side from the object side plane 322. The sixth lens 320 can also be a lens that is recessed towards the object side from the image side plane 324.

[0140] The seventh lens 410 can be a lens that is concave to the object side plane 412. The seventh lens 410 can also be a lens that is concave to the object side plane 414. The eighth lens 420 can be a lens that is concave to the object side plane 422. The eighth lens 420 can also be a lens that is concave to the object side plane 424.

[0141] The first lens 110 to the eighth lens 420 can be lenses with positive or negative refractive power.

[0142] The first lens 110 can have positive refractive power. The second lens 120 can have negative refractive power. The third lens 210 can have positive refractive power. The fourth lens 220 can have negative refractive power. The fifth lens 310 can have negative refractive power. The sixth lens 320 can have negative refractive power. The seventh lens 410 can have positive refractive power. The eighth lens 420 can have positive refractive power.

[0143] refer to Figure 2a When the distance between the first lens group 100 and the second lens group 200 is d1a, the distance between the second lens group 200 and the third lens group 300 is d2a, and the distance between the third lens group 300 and the fourth lens group 400 is d3a, the zoom optical system can have a wide angle (e.g., 3x magnification).

[0144] exist Figure 2b In this system, when the distance between the first lens group 100 and the second lens group 200 is d1b, the distance between the second lens group 200 and the third lens group 300 is d2b, and the distance between the third lens group 300 and the fourth lens group 400 is d3b, the zoom optical system can have an intermediate mode.

[0145] exist Figure 2c In this system, when the distance between the first lens group 100 and the second lens group 200 is d1c, the distance between the second lens group 200 and the third lens group 300 is d2c, and the distance between the third lens group 300 and the fourth lens group 400 is d3c, the zoom optical system can have a telephoto lens (e.g., 7.5x magnification).

[0146] The distance between adjacent lens groups can change when changing the magnification from wide-angle to telephoto.

[0147] The distance between the first lens group 100 and the second lens group 200 can be changed from d1a to d1c via d1b. At this time, the distance between the first lens group 100 and the second lens group 200 can gradually decrease (d1a>d1b>d1c).

[0148] The distance between the second lens group 200 and the third lens group 300 can be changed from d2a to d2c via d2b. At this time, the distance between the second lens group 200 and the third lens group 300 can be decreased and then increased again (d2b). <d2a<d2c)。

[0149] The distance between the third lens group 300 and the fourth lens group 400 can be changed from d3a to d3c via d3b. At this time, the distance between the third lens group 300 and the fourth lens group 400 can be gradually increased (d3a... <d3b<d3c)。

[0150] As described above, the second lens group 200 and the third lens group 300 can have different moving speeds.

[0151] As the second lens group 200 and the third lens group 300 move, the magnification of the zoom optical system can be continuously adjusted from 5x to 7.5x.

[0152] Next, we will refer to Figures 3a to 3c Simulation results of longitudinal spherical aberration, astigmatism curve, and distortion of a zoom optical system according to a first embodiment of the present invention are described. Longitudinal spherical aberration represents the longitudinal spherical aberration per wavelength, astigmatism curve represents the aberration characteristics of the tangent and sagittal planes relative to the height of the image plane, and distortion represents the degree of distortion relative to the height of the image plane.

[0153] Figure 3a The graph is obtained by measuring the longitudinal spherical aberration, astigmatism curve, and distortion of light having wavelengths of 435 nm, 486 nm, 546 nm, 587 nm, and 656 nm in the wide-angle field of the optical system according to the first embodiment.

[0154] Figure 3b The graph is obtained by measuring the longitudinal spherical aberration, astigmatism curve, and distortion of light having wavelengths of 435 nm, 486 nm, 546 nm, 587 nm, and 656 nm in an intermediate mode of the optical system according to the first embodiment.

[0155] Figure 3c The graph is obtained by measuring the longitudinal spherical aberration, astigmatism curve, and distortion of light having wavelengths of 435 nm, 486 nm, 546 nm, 587 nm, and 656 nm in the telephoto lens of the optical system according to the first embodiment.

[0156] refer to Figures 3a to 3c It can be seen that, regardless of wavelength, the longitudinal spherical aberration ranges from -0.05 mm to 0.05 mm from the center to the edge of the image sensor. Specifically, it can be seen that the longitudinal spherical aberration in wide-angle mode ranges from approximately -0.1 mm to 0.025 mm, and in intermediate mode it ranges from -0.02 mm to 0.05 mm. It can be seen that, although some wavelengths extend beyond the range near the center of the sensor, the longitudinal spherical aberration in telephoto mode is within the range of approximately -0.05 mm to 0.05 mm.

[0157] refer to Figures 3a to 3c It can be seen that, regardless of wavelength, the astigmatism curve ranges from -0.05 mm to 0.02 mm from the center to the edge of the image sensor. Specifically, it can be seen that the astigmatism curve in wide-angle mode is in the range of approximately -0.01 mm to 0.02 mm, and the astigmatism curve in intermediate mode is in the range of -0.01 mm to 0.02 mm. It can be seen that the astigmatism curve in telephoto mode is in the range of approximately -0.05 mm to -0.02 mm.

[0158] refer to Figures 3a to 3c It can be seen that, regardless of wavelength, the distortion ranges from -0.5 mm to 2.5 mm from the center to the edge of the image sensor. Specifically, it can be seen that the distortion in wide-angle mode is in the range of approximately -0.5 mm to 1.0 mm, and the astigmatism curve in intermediate mode is in the range of 0 mm to 2.5 mm. It can be seen that the astigmatism curve in telephoto mode is in the range of approximately 0 mm to 0.5 mm.

[0159] Next, we will refer to Figures 4a to 4c The simulation results of the modulation transfer function (MTF) of the zoom optical system according to a first embodiment of the present invention are described. The modulation transfer function (MTF) is one of the methods for measuring the performance of an optical system.

[0160] Figure 4a This is a diffraction MTF pattern in the wide-angle view of the optical system according to the first embodiment.

[0161] Figure 4b It is a diffraction MTF pattern in the intermediate mode of the optical system according to the first embodiment.

[0162] Figure 4c It is a diffraction MTF pattern in the telephoto lens of the optical system according to the first embodiment.

[0163] refer to Figures 4a to 4cAccording to an embodiment of the present invention, the zoom optical system has a value close to the diffraction limit near the defocus position 0 in each of the wide-angle, intermediate, and telephoto modes, which is the limiting value.

[0164] Figure 5 The graph is obtained by measuring the relative illumination of the zoom optical system according to the first embodiment of the present invention.

[0165] refer to Figure 5 It can be seen that the zoom optical system according to the first embodiment of the present invention has a relative illumination value of 50% or higher in all of the wide-angle (zoom position 1), intermediate mode (zoom position 2) and telephoto (zoom position 3), and has a relative illumination value of 80% or higher in the intermediate mode and telephoto.

[0166] As can be seen from the embodiments described, the optical system according to the embodiments of the present invention has excellent aberration characteristics.

[0167] Figure 6 A zoom optical system according to a second embodiment of the present invention is shown.

[0168] refer to Figure 6 According to a second embodiment of the present invention, the zoom optical system includes a first lens group 100, a second lens group 200, a third lens group 300, and a fourth lens group 400 arranged sequentially from the object side to the image side. A right-angle prism may also be arranged at the front end of the first lens group 100.

[0169] According to a second embodiment of the present invention, the first lens group 100 includes a plurality of lenses. The first lens group 100 may include at least two or more lenses. Since it may be difficult to correct the resolution at maximum magnification when the first lens group 100 includes a single lens, and the overall size of the zoom optical system may increase when the first lens group 100 includes three or more lenses, the first lens group 100 may preferably include two lenses 110 and 120.

[0170] The first lens group 100 is fixed to the image side. The first lens group 100 is fixed to the plane of the sensor 10. In other words, multiple lenses are fixed to the image side. When the first lens group 100 includes two lenses, the two lenses 110 and 120 can be fixed to the image side.

[0171] The second lens group 200 includes a plurality of lenses. The second lens group 200 may include at least two lenses. Since it may be difficult to correct the resolution at maximum magnification when the second lens group 200 includes a single lens, and the overall size of the zoom optical system may increase when the second lens group 200 includes three or more lenses, the second lens group 200 may preferably include two lenses 210 and 220.

[0172] The second lens group 200 is movable. Multiple lenses included in the second lens group 200 are movable together along the central axis of the lens. Two lenses 210 and 220 included in the second lens group 200 are movable together along the central axis of the lens. When the second lens group 200 includes three or more lenses, the size and weight of the second lens group 200 may increase, and the driving force may increase with movement. Therefore, the second lens group 200 preferably includes two lenses 210 and 220. The focal length can be continuously adjusted according to the movement of the second lens group 200. The magnification can be continuously adjusted according to the movement of the second lens group 200. Therefore, the second lens group 200 can be used as a zoom group.

[0173] The third lens group 300 includes multiple lenses. The third lens group 300 may include at least two lenses. Since it may be difficult to correct the resolution at maximum magnification when the third lens group 300 includes a single lens, and the overall size of the zoom optical system may increase when the third lens group 300 includes three or more lenses, the third lens group 300 may preferably include two lenses 310 and 320.

[0174] The third lens group 300 is movable. Multiple lenses included in the third lens group 300 are movable together along the central axis of the lens. Two lenses 310 and 320 included in the third lens group 300 are movable together along the central axis of the lens. When the third lens group 300 includes three or more lenses, the size and weight of the third lens group 300 may increase, and the driving force may increase with movement. Therefore, the third lens group 300 preferably includes two lenses 310 and 320. The focus can be adjusted according to the movement of the third lens group 300. The third lens group 300 can be used as a focusing group.

[0175] The fourth lens group 400 includes multiple lenses. The fourth lens group 400 may include at least two lenses. Since it may be difficult to correct the resolution at maximum magnification when the fourth lens group 400 includes a single lens, and the overall size of the zoom optical system may increase when the fourth lens group 400 includes three or more lenses, the fourth lens group 400 may preferably include two lenses 410 and 420.

[0176] The fourth lens group 400 is fixed to the image side. The fourth lens group 400 is fixed to the plane of the sensor 10. In other words, multiple lenses are fixed to the image side. When the fourth lens group 400 includes two lenses, the two lenses 410 and 420 can be fixed to the image side.

[0177] According to a second embodiment of the present invention, the filter 20 and the image sensor 10 can be arranged sequentially at the rear end of the fourth lens group 400. In this case, the filter 20 can be an infrared (IR) filter. Therefore, the filter 20 can block near-infrared light (e.g., light with wavelengths from 700 nm to 1100 nm) from the light incident on the camera module. Furthermore, the image sensor 10 can be connected to a printed circuit board via a cable.

[0178] Filter 20 may also include an anti-foreign object filter and an IR filter arranged sequentially from the object side to the image side. When filter 20 includes an anti-foreign object filter, it can prevent foreign objects generated during the movement of the third lens group 300 from being introduced into the IR filter or the image sensor 10.

[0179] The magnification of the zoom optical system can vary depending on the movement of the second lens group 200 and the third lens group 300. For example, the magnification of the zoom optical system can continuously increase or decrease between 3x and 7.5x depending on the movement of the second lens group 200 and the third lens group 300. According to the second embodiment, the zoom optical system can have a magnification of 3x in the wide-angle field and a magnification of 7.5x in the telephoto field. Furthermore, when the magnification increases or decreases continuously, it may mean that the magnification does not increase or decrease intermittently numerically, but rather linearly.

[0180] Each of the second lens group 200 and the third lens group 300 can move independently. For example, when the zoom optical system moves from wide-angle to telephoto, the distance between the second lens group 200 and the third lens group 300 can increase from the starting point of the movement (wide-angle) to a predetermined point, and then gradually decrease from the predetermined point to the ending point of the movement (telephoto).

[0181] The effective focal length (EFL) of a zoom optical system according to a second embodiment of the present invention will be described.

[0182] In a zoom optical system, the effective focal length at the telephoto end can be represented by the following mathematical expression 7:

[0183] [Mathematical Expression 7]

[0184]

[0185] Among them, EFL tele This refers to the effective focal length of a zoom optical system in the telephoto range, and H imageD This refers to half the diagonal length of the pixel area of ​​the image sensor. The unit can be [mm].

[0186] In a zoom optical system, the effective focal length in the wide-angle range can be represented by the following mathematical expression:

[0187] [Mathematical Expression 8]

[0188]

[0189] Among them, EFL wide This refers to the effective focal length of a zoom optical system in a wide-angle field, and H imageD It refers to half the diagonal length of the pixel area of ​​the image sensor.

[0190] The travel distance of a zoom optical system according to a second embodiment of the present invention will be described. The travel distance can refer to the distance the lens group can be moved by the drive unit.

[0191] The travel distance of the second lens group 200 can be represented by the following mathematical expression 9:

[0192] [Mathematical Expression 9]

[0193]

[0194] The total track length (TTL) can refer to the distance from the image sensor plane to the first plane of the zoom optical system. For example, TTL can refer to the distance from the plane closest to the object side of the first lens group 100 to the upper plane of the image sensor 10 on which light is incident. In this specification, TTL can be used interchangeably with the total length distance. STROKE2 can refer to the travel distance of the second lens group 200. The unit can be [mm].

[0195] The travel distance of the third lens group 300 can be represented by the following mathematical expression 10:

[0196] [Mathematical Expression 10]

[0197]

[0198] Here, TTL can refer to the distance from the image sensor plane to the first plane of the zoom optical system. STROKE3 can refer to the travel distance of the third lens group 300. The unit can be [mm].

[0199] When the travel distance is large, it becomes difficult to install the drive unit in a portable terminal because the size of the drive unit, configured to move the second lens group 200 and the third lens group 300, increases. However, compared to TTL, by implementing the travel distance as 1 / 4 to 1 / 3, the size of the drive unit can be reduced, thereby miniaturizing the camera module.

[0200] The Abbe number of a zoom optical system according to a second embodiment of the present invention will be described. The Abbe number can refer to a numerical value of a property related to the light dispersion of a lens.

[0201] Multiple lenses included in the second lens group 200 can have different Abbe numbers. When the second lens group 200 includes two lenses, the Abbe numbers of the two lenses included in the second lens group 200 can be represented by the following mathematical expression 11:

[0202] [Mathematical Expression 11]

[0203] |ABBE3-ABBE4|>10 Wherein, ABBE3 may refer to the Abbe number of the lens on the object-side plane of the two lenses included in the second lens group 200, and ABBE4 may refer to the Abbe number of the lens on the image-side plane of the two lenses included in the second lens group 200. According to the second embodiment, ABBE3 may refer to the Abbe number of the third lens 210, and ABBE4 may refer to the Abbe number of the fourth lens 220.

[0204] According to a second embodiment of the present invention, the zoom optical system can remove chromatic aberration by arranging two lenses having Abbe numbers that differ from each other by a predetermined value or greater in each of the second lens group 200 and the fourth lens group 400.

[0205] The aperture of the lens of the zoom optical system according to a second embodiment of the present invention will be described.

[0206] According to a second embodiment of the present invention, the apertures of the second lens group 200 and the third lens group 300 can be smaller than the apertures of the first lens group 100 and the fourth lens group 400. This can be expressed by the following mathematical expression 12:

[0207] [Mathematical Expression 12]

[0208]

[0209] Among them, APER fix This can refer to the maximum diameter of the lenses included in the first lens group 100 and the fourth lens group 400, which are fixed groups, and APER mov This can refer to the maximum diameter of the lenses included in the second lens group 200 and the third lens group 300, which are movable groups. For example, when the diameter of the first lens 110 is the largest among the lenses included in the first lens group 100 and the fourth lens group 400, which are fixed groups, APER fix This can refer to the diameter of the first lens 110. When the diameter of the third lens 210 is the largest among the lenses included in the second lens group 200 and the third lens group 300, which are movable groups, APER... mov It could refer to the diameter of the third lens 210.

[0210] By making the apertures of the second lens group 200 and the third lens group 300 smaller than those of the first lens group 100 and the fourth lens group 400, the weight of the second lens group 200 and the third lens group 300 can be reduced. Therefore, when the second lens group 200 and the third lens group 300 (as a movable group) move, power consumption can be reduced.

[0211] According to a second embodiment of the present invention, the plurality of lenses 110, 120, 210, 220, 310, 320, 410, and 420 included in the first lens group 100 to the fourth lens group 400 may be lenses employing D-cut technology. The plurality of lenses 110, 120, 210, 220, 310, 320, 410, and 420 included in the first lens group 100 to the fourth lens group 400 may be D-cut lenses having partially cut upper and lower portions. In this case, the upper and lower portions of the plurality of lenses 110, 120, 210, 220, 310, 320, 410, and 420 may have partially cut ribs and an effective diameter, or only have cut ribs without a cut effective diameter. According to one embodiment, the second lens group 200 and the third lens group may include lenses whose value is 1 obtained by dividing the major axis length of the effective diameter by the minor axis length of the effective diameter. In other words, the major axis of the effective diameter can be the same as the minor axis. For example, the upper and lower portions of the fifth lens 220, the sixth lens 310, and the seventh lens 320 can have only cut ribs without cutting the effective diameter. Circular lenses have the problem that the lens volume increases with vertical height, but as in the second embodiment of the invention, the vertical height can be reduced by applying D-cut technology to the upper and lower portions of multiple lenses 110, 120, 210, 220, 310, 320, 410, and 420, thereby reducing the lens volume.

[0212] According to a second embodiment of the present invention, the first lens group 100 may include a plurality of lenses with different refractive powers. The first lens 110 and the second lens 120 included in the first lens group 100 may have different refractive powers. According to the second embodiment, the first lens 110 may have a positive (+) refractive power, and the second lens 120 may have a negative (-) refractive power.

[0213] According to a second embodiment of the present invention, each of the first lens group 100 to the fourth lens group 400 may include a plastic lens. In this case, each of the first lens group 100 and the second lens group 200 may include a glass lens. At least one of the plurality of lenses included in the first lens group 100 and the second lens group 200 may be a glass lens.

[0214] According to one embodiment, the second lens 120 disposed on the image side of the lens included in the first lens group 100 may be a glass lens. According to another embodiment, the third lens 210 disposed on the object side of the lens included in the second lens group 200 may be a glass lens. According to yet another embodiment, both the second lens 120 disposed on the image side of the lens included in the first lens group 100 and the third lens 210 disposed on the object side of the lens included in the second lens group 200 may be glass lenses.

[0215] Figure 7a This is a cross-sectional view of the zoom optical system of the second embodiment of the present invention in the wide-angle direction. Figure 7b This is a cross-sectional view of the zoom optical system in intermediate mode according to the second embodiment of the present invention, and Figure 7c This is a cross-sectional view of the telephoto lens of the zoom optical system according to the second embodiment of the present invention.

[0216] Tables 5 and 6 below show the optical characteristics of lenses included in a zoom optical system according to a second embodiment of the present invention, and Tables 7 and 8 show the conic constants and aspherical coefficients of lenses included in a zoom optical system according to a second embodiment of the present invention.

[0217] Table 5

[0218]

[0219]

[0220] Table 6

[0221]

[0222] Table 7

[0223]

[0224]

[0225] Table 8

[0226]

[0227] refer to Figures 7a to 7cAs per Tables 5 to 8, the zoom optical system includes a first lens group 100, a second lens group 200, a third lens group 300, and a fourth lens group 400 arranged sequentially from the object side to the image side. The first lens group 100 includes a first lens 110 and a second lens 120 arranged sequentially from the object side to the image side. The second lens group 200 includes a third lens 210 and a fourth lens 220 arranged sequentially from the object side to the image side. The third lens group 300 includes a fifth lens 310 and a sixth lens 320 arranged sequentially from the object side to the image side. The fourth lens group 400 includes a seventh lens 410 and an eighth lens 420 arranged sequentially from the object side to the image side.

[0228] In Table 5, the thickness (mm) represents the distance from each lens plane to the next lens plane.

[0229] For example, the thickness described on the object-side plane 112 of the first lens 110 represents the distance from the object-side plane 112 of the first lens 110 to the image-side plane 114. Specifically, the thickness described on the object-side plane 112 of the first lens 110 represents the distance between the center of curvature of the object-side plane 112 and the center of curvature of the image-side plane 114 in the first lens 110.

[0230] The thickness described on the image-side plane 114 of the first lens 110 represents the distance from the image-side plane 114 of the first lens 110 to the object-side plane 122 of the second lens 120. Specifically, the thickness described on the image-side plane 114 of the first lens 110 represents the distance between the center of curvature of the image-side plane 114 of the first lens 110 and the center of curvature of the object-side plane 122 of the second lens 120.

[0231] The thickness described on the image-side plane 124 of the second lens 120 represents the distance from the image-side plane 124 of the second lens 120 to the object-side plane 212 of the third lens 210. Specifically, the thickness described on the image-side plane 124 of the second lens 120 represents the distance between the center of curvature of the image-side plane 124 of the second lens 120 and the center of curvature of the object-side plane 212 of the third lens 210.

[0232] At this time, because the second lens group 200 moves during the zoom process from wide-angle to telephoto, the thickness described on the image side plane 124 of the second lens 120 can vary. The thickness described on the image side plane 124 of the second lens 120 can have a value between the shortest and longest distances. Referring to Table 5, the thickness described on the image side plane 124 of the second lens 120 can have the longest distance (6.8) in wide-angle mode. The thickness described on the image side plane 124 of the second lens 120 can have a value between the shortest and longest distances (3.039444812) in intermediate mode. The thickness described on the image side plane 124 of the second lens 120 can have the shortest distance (0.3) in telephoto mode. The thickness described on the image side plane 224 of the fourth lens 220 is also the same as the thickness described on the image side plane 324 of the sixth lens 320.

[0233] Referring to Table 5, it can be seen that the Abbe number difference between the third lens 210 and the fourth lens 220, which are included in the second lens group 200, is 10 or greater. Specifically, it can be seen that since the Abbe number of the third lens 210 is 81.5596 and the Abbe number of the fourth lens 220 is 19.2425, the Abbe number difference between the two lenses is approximately 62, and therefore the difference is 10 or greater.

[0234] Referring to Table 5, it can be seen that any one of the first lens 110 to the fourth lens 220 included in the first lens group 100 and the second lens group 200 is a glass lens. Specifically, it can be seen that the first lens 110, the second lens 120 and the fourth lens 220 are plastic lenses, and the third lens 210 is a glass lens.

[0235] Referring to Table 6, each plane of the first lens 110 to the eighth lens 420 can be convex or concave.

[0236] The first lens 110 can be a lens that bulges from the object-side plane 112 toward the object side. The first lens 110 can also be a lens that is recessed from the image-side plane 114 toward the object side. The second lens 120 can be a lens that bulges from the object-side plane 122 toward the object side. The second lens 120 can also be a lens that bulges from the image-side plane 124 toward the object side.

[0237] The third lens 210 can be a lens that bulges from the object-side plane 212 toward the object side. The third lens 210 can also be a lens that is recessed from the image-side plane 214 toward the object side. The fourth lens 220 can be a lens that is recessed from the object-side plane 222 toward the object side. The fourth lens 220 can also be a lens that bulges from the image-side plane 224 toward the object side.

[0238] The fifth lens 310 can be a lens that bulges towards the object side from the object side plane 312. The fifth lens 310 can also be a lens that bulges towards the object side from the image side plane 314. The sixth lens 320 can be a lens that bulges towards the object side from the object side plane 322. The sixth lens 320 can also be a lens that is recessed towards the object side from the image side plane 324.

[0239] The seventh lens 410 can be a lens that is concave to the object side plane 412. The seventh lens 410 can also be a lens that is concave to the object side plane 414. The eighth lens 420 can be a lens that is concave to the object side plane 422. The eighth lens 420 can also be a lens that is convex to the object side plane 424.

[0240] The first lens 110 to the eighth lens 420 can be lenses with positive or negative refractive power.

[0241] The first lens 110 can have positive refractive power. The second lens 120 can have negative refractive power. The third lens 210 can have positive refractive power. The fourth lens 220 can have negative refractive power. The fifth lens 310 can have negative refractive power. The sixth lens 320 can have negative refractive power. The seventh lens 410 can have positive refractive power. The eighth lens 420 can have positive refractive power.

[0242] refer to Figure 7a When the distance between the first lens group 100 and the second lens group 200 is d1a, the distance between the second lens group 200 and the third lens group 300 is d2a, and the distance between the third lens group 300 and the fourth lens group 400 is d3a, the zoom optical system can have a wide angle (e.g., 3x magnification).

[0243] exist Figure 7b In this system, when the distance between the first lens group 100 and the second lens group 200 is d1b, the distance between the second lens group 200 and the third lens group 300 is d2b, and the distance between the third lens group 300 and the fourth lens group 400 is d3b, the zoom optical system can have an intermediate mode.

[0244] exist Figure 7c In this system, when the distance between the first lens group 100 and the second lens group 200 is d1c, the distance between the second lens group 200 and the third lens group 300 is d2c, and the distance between the third lens group 300 and the fourth lens group 400 is d3c, the zoom optical system can have a telephoto lens (e.g., 7.5x magnification).

[0245] The distance between adjacent lens groups can change when changing the magnification from wide-angle to telephoto.

[0246] The distance between the first lens group 100 and the second lens group 200 can be changed from d1a to d1c via d1b. At this time, the distance between the first lens group 100 and the second lens group 200 can gradually decrease (d1a>d1b>d1c).

[0247] The distance between the second lens group 200 and the third lens group 300 can be changed from d2a to d2c via d2b. At this time, the distance between the second lens group 200 and the third lens group 300 can be decreased and then increased again (d2b). <d2a<d2c)。

[0248] The distance between the third lens group 300 and the fourth lens group 400 can be changed from d3a to d3c via d3b. At this time, the distance between the third lens group 300 and the fourth lens group 400 can be gradually increased (d3a... <d3b<d3c)。

[0249] As described above, the second lens group 200 and the third lens group 300 can have different moving speeds.

[0250] As the second lens group 200 and the third lens group 300 move, the magnification of the zoom optical system can be continuously adjusted from 5x to 7.5x.

[0251] Next, we will refer to Figures 8a to 8c The simulation results of longitudinal spherical aberration, astigmatism curve, and distortion of a zoom optical system according to a second embodiment of the present invention are described. Longitudinal spherical aberration represents the longitudinal spherical aberration per wavelength, astigmatism curve represents the aberration characteristics of the tangential and sagittal planes relative to the height of the image plane, and distortion represents the degree of distortion relative to the height of the image plane.

[0252] Figure 8a The graph is obtained by measuring the longitudinal spherical aberration, astigmatism curve, and distortion of light having wavelengths of 435 nm, 486 nm, 546 nm, 587 nm, and 656 nm in the wide-angle field of the optical system according to the second embodiment.

[0253] Figure 8b The graph is obtained by measuring the longitudinal spherical aberration, astigmatism curve, and distortion of light having wavelengths of 435 nm, 486 nm, 546 nm, 587 nm, and 656 nm in an intermediate mode of the optical system according to the second embodiment.

[0254] Figure 8c The graph is obtained by measuring the longitudinal spherical aberration, astigmatism curve, and distortion of light having wavelengths of 435 nm, 486 nm, 546 nm, 587 nm, and 656 nm in the telephoto lens of the optical system according to the second embodiment.

[0255] refer to Figures 8a to 8c It can be seen that, regardless of wavelength, the longitudinal spherical aberration ranges from -0.07 mm to 0.2 mm from the center to the edge of the image sensor. Specifically, it can be seen that the longitudinal spherical aberration in wide-angle mode is in the range of approximately -0.02 mm to 0.1 mm, and in intermediate mode it is in the range of -0.05 mm to 0.2 mm. It can be seen that, although some wavelengths extend beyond the range near the center of the sensor, the longitudinal spherical aberration in telephoto is in the range of approximately -0.07 mm to 0.2 mm.

[0256] refer to Figures 8a to 8c It can be seen that, regardless of wavelength, the astigmatism curve ranges from 0 mm to 0.1 mm from the center to the edge of the image sensor. Specifically, it can be seen that the astigmatism curve in wide-angle mode ranges from approximately 0 mm to 0.05 mm, and the astigmatism curve in intermediate mode ranges from 0 mm to 0.1 mm. It can be seen that the astigmatism curve in telephoto mode ranges from approximately 0 mm to 0.1 mm.

[0257] refer to Figures 8a to 8c It can be seen that, regardless of wavelength, the distortion ranges from 0 mm to 2.5 mm from the center to the edge of the image sensor. Specifically, it can be seen that the distortion in wide-angle mode is in the range of approximately 0 mm to 2.5 mm, and the distortion in intermediate mode is in the range of 0 mm to 2.5 mm. It can be seen that the distortion in telephoto mode is in the range of approximately 0 mm to 2 mm.

[0258] Next, we will refer to Figures 9a to 9c The MTF simulation results of a zoom optical system according to a second embodiment of the present invention are described. Modulation transfer function (MTF) is a method for measuring the performance of an optical system.

[0259] Figure 9a This is a diffraction MTF diagram in the wide-angle view of the optical system according to the second embodiment. Figure 9b It is a diffraction MTF pattern in the intermediate mode of the optical system according to the second embodiment. Figure 9c This is a diffraction MTF pattern in the telephoto lens of the optical system according to the second embodiment.

[0260] refer to Figures 9a to 9c According to an embodiment of the present invention, the zoom optical system has a value close to the diffraction limit near the defocus position 0 in each of the wide-angle, intermediate, and telephoto modes, which is the limiting value.

[0261] Figure 10The graph is obtained by measuring the relative illumination of the zoom optical system according to the second embodiment of the present invention.

[0262] refer to Figure 10 It can be seen that the zoom optical system according to the second embodiment of the present invention has a relative illumination value of 60% or higher in all of the wide-angle (zoom position 2), intermediate mode (zoom position 2) and telephoto (zoom position 3), and has a relative illumination value of 80% or higher in the intermediate mode and telephoto.

[0263] As can be seen from the embodiments described, the optical system according to the embodiments of the present invention has excellent aberration characteristics.

[0264] Meanwhile, the zoom optical system according to embodiments of the present invention can be applied to a camera module. A camera module including a zoom optical system according to an embodiment of the present invention can be built into a portable terminal and used together with a main camera module. A camera module according to an embodiment of the present invention may include an image sensor, a filter disposed on the image sensor, and a zoom optical system disposed on the filter. The zoom optical system according to an embodiment of the present invention may include a first lens group 100, a second lens group 200, a third lens group 300, and a fourth lens group 400 as described above. A portable terminal with a built-in camera module including a zoom optical system according to an embodiment of the present invention can be a smartphone, tablet PC, laptop computer, personal digital assistant (PDA), etc. The optical system according to an embodiment of the present invention can be applied to a camera module.

[0265] Figure 11 A portion of a portable terminal employing a camera module according to an embodiment of the present invention is shown.

[0266] refer to Figure 11 A camera module, including a zoom optical system 1000 according to an embodiment of the present invention, can be built into a portable terminal and used together with a main camera module 1100.

[0267] The zoom optical system 1000 according to an embodiment of the present invention includes a first lens group 100, a second lens group 200, a third lens group 300, and a fourth lens group 400 as described above. Due to the thickness limitations of the portable terminal, the first lens group 100, the second lens group 200, the third lens group 300, and the fourth lens group 400 can be arranged sequentially in the lateral direction of the portable terminal. For this purpose, as described above, a right-angle prism can also be arranged at the front end of the first lens group 100. When the zoom optical system is arranged in the thickness direction of the portable terminal, that is, when the lens plane of the lens included in the zoom optical system is arranged in the thickness direction of the portable terminal, the thickness of the portable terminal can be reduced by decreasing the diameter of the lens included in the zoom optical system. Therefore, even in a portable terminal, a zoom optical system capable of continuously adjusting the magnification by moving the lens can be built in.

[0268] A portable terminal that incorporates a camera module including a zoom optical system according to an embodiment of the present invention can be a smartphone, tablet PC, laptop computer, PDA, etc.

[0269] Although the foregoing primarily describes embodiments, this is merely illustrative and does not limit the invention. Those skilled in the art will understand that various modifications and applications not illustrated above are possible without departing from the essential characteristics of the embodiments. For example, the various components specifically shown in this embodiment can be implemented through modifications. Furthermore, differences relating to modifications and applications should be interpreted as including within the scope of the invention as defined in the appended claims.

Claims

1. A zoom optical system, comprising: The first lens group, the second lens group, the third lens group, and the fourth lens group are arranged sequentially from the object side to the image side. Each of the first to fourth lens groups includes two lenses. The second lens group and the third lens group are movable, and The first lens group includes a first lens and a second lens arranged sequentially from the object side to the image side. The first lens has an object-side plane that bulges toward the object and an image-side plane that is recessed toward the object. The second lens has an object-side plane convex toward the object side and an image-side plane convex toward the object side. The effective focal length (EFL) in telephoto lenses is defined by the following mathematical expression: Among them, EFL tele This refers to the effective focal length of the zoom optical system in the telephoto range, and H imageD It refers to half the diagonal length of the pixel area of ​​the image sensor.

2. The zoom optical system according to claim 1, wherein, The effective focal length (EFL) in a wide-angle lens is defined by the following mathematical expression: Among them, EFL wide This refers to the effective focal length of the zoom optical system in the wide-angle section, and H imageD This refers to half the diagonal length of the pixel region of the image sensor.

3. The zoom optical system according to claim 1, wherein, When zooming from wide-angle to telephoto, the travel distance of the second lens group is defined by the following mathematical expression: Wherein, the total track length (TTL) refers to the distance between the image sensor plane and the first plane of the zoom optical system, and STROKE2 refers to the travel distance of the second lens group.

4. The zoom optical system according to claim 1, wherein, When zooming from wide-angle to telephoto, the travel distance of the third lens group is defined by the following mathematical expression: Wherein, the total track length (TTL) refers to the distance between the image sensor plane and the first plane of the zoom optical system, and STROKE3 refers to the travel distance of the third lens group.

5. The zoom optical system according to claim 1, wherein, Each of the first lens group and the second lens group includes at least one glass lens.

6. The zoom optical system according to claim 5, wherein, At least one of the lenses arranged on the image side of the two lenses included in the first lens group or on the object side of the two lenses included in the second lens group is a glass lens.

7. The zoom optical system according to claim 1, wherein, The two lenses included in the second lens group have Abbe numbers defined by the following mathematical expression: Wherein, ABBE3 refers to the Abbe number of the lens on the object-side plane of the two lenses included in the second lens group, and ABBE4 refers to the Abbe number of the lens on the image-side plane of the two lenses included in the second lens group.

8. The zoom optical system according to claim 1, wherein, At least one of the lenses included in the first to fourth lens groups is a D-cut lens.

9. The zoom optical system according to claim 7, wherein, At least one of the lenses included in the first to fourth lens groups has an upper portion and a lower portion, the upper portion and the lower portion having partially cut ribs and an effective diameter, or having only cut ribs without cutting the effective diameter.

10. The zoom optical system according to claim 1, wherein, The second lens group and the third lens group include lenses in which a value of 1 is obtained by dividing the major axis length of the effective diameter by the minor axis length of the effective diameter.

11. The zoom optical system according to claim 1, wherein, The maximum diameter of the plurality of lenses included in the first lens group and the fourth lens group, as well as the maximum diameter of the plurality of lenses included in the second lens group and the third lens group, are defined by the following mathematical expressions: Among them, APER fix This refers to the maximum diameter of the lenses included in the first lens group and the fourth lens group, where the first lens group and the fourth lens group are fixed groups, and APER... mov This refers to the maximum diameter of the lenses included in the second lens group and the third lens group, which are movable groups.

12. The zoom optical system according to claim 1, wherein, The lens arranged on the object side of the two lenses included in the first lens group has positive refractive power, and The lens arranged on the image side of the two lenses included in the first lens group has negative refractive power.

13. The zoom optical system according to claim 1, wherein, The second lens group and the third lens group have different moving speeds.

14. The zoom optical system according to claim 1, wherein, The filter and the image sensor are arranged sequentially at the rear end of the fourth lens group.

15. The zoom optical system according to claim 1, wherein, The second lens group includes a third lens and a fourth lens, the third lens group includes a fifth lens and a sixth lens, and the fourth lens group includes a seventh lens and an eighth lens.

16. The zoom optical system according to claim 15, wherein, The first lens, the third lens, the seventh lens, and the eighth lens have positive refractive power, and the second lens, the fourth lens, the fifth lens, and the sixth lens have negative refractive power.

17. A zoom optical system, comprising: The first lens group, the second lens group, the third lens group, and the fourth lens group are arranged sequentially from the object side to the image side. Each of the first to fourth lens groups includes two lenses. The second lens group and the third lens group are movable, and The first lens group includes a first lens and a second lens arranged sequentially from the object side to the image side. The first lens has an object-side plane that bulges toward the object and an image-side plane that is recessed toward the object. The second lens has an object-side plane convex toward the object side and an image-side plane convex toward the object side. The effective focal length (EFL) in a wide-angle shot is defined by the following mathematical expression: Among them, EFL wide This refers to the effective focal length of the zoom optical system in the wide-angle section, and H imageD It refers to half the diagonal length of the pixel area of ​​the image sensor.

18. The zoom optical system according to claim 17, wherein, Each of the first lens group and the second lens group includes at least one glass lens, and At least one of the lenses arranged on the image side of the two lenses included in the first lens group or on the object side of the two lenses included in the second lens group is a glass lens.

19. The zoom optical system according to claim 17, wherein, At least one of the lenses included in the first to fourth lens groups is a D-cut lens.

20. The zoom optical system according to claim 17, wherein, The first lens group includes a first lens and a second lens, the second lens group includes a third lens and a fourth lens, the third lens group includes a fifth lens and a sixth lens, and the fourth lens group includes a seventh lens and an eighth lens.

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