Optical system and camera module

Abstract

An optical system disclosed in an embodiment of the present invention comprises: a first reflective member; a second reflective member spaced apart from the first reflective member; a first lens group disposed between the first reflective member and an object; and a second lens group disposed between the first reflective member and the second reflective member, wherein the number of lenses in the first lens group is greater than the number of lenses in the second lens group, the first lens group has positive power, the second lens group has negative power, and the first lens, from among the lenses of the first lens group, closest to the object may have positive power.

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 capture objects and store them as images or videos, and are used in a variety of applications. In particular, camera modules are manufactured in ultra-small sizes and are used in portable devices such as smartphones, tablet PCs, and laptops, as well as drones and vehicles, providing a variety of functions.

[0003] 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 may 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 may perform a zooming function of zooming up or zooming out to increase or decrease the magnification of a distant object to capture the image through a zoom lens. In addition, the camera module adopts an image stabilization (IS) technology to correct or prevent shaking of the image caused by movement of the camera due to an unstable fixing device or movement of the user.

[0004] The most crucial element for these camera modules to capture images is the imaging lens that forms the image. Recently, interest in high resolution has been growing, and research is being conducted on optical systems that incorporate multiple lenses to achieve this. For example, research is underway on utilizing multiple imaging lenses with positive or negative refractive power to achieve high resolution.

[0005] However, when multiple lenses are included, there is a problem in that it is difficult to derive excellent optical characteristics 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, and as a result, there is a problem in that the overall size of the module including the multiple lenses increases.

[0006] Additionally, image sensor sizes are increasing to achieve high resolution and high image quality. However, as image sensor sizes increase, the TTL (Total Track Length) 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.

[0007] Therefore, a new optical system capable of solving the above-described problems is required.

[0008] Embodiments of the invention can provide an optical system and a camera module having a first lens group having a plurality of lenses between an object and a first reflective member, and lenses less than or equal to the first lens group between the first reflective member and the second reflective member. Accordingly, an image sensor can be arranged in a direction parallel to an axial direction passing through the centers of the plurality of reflective members. In other words, an optical system and a camera module are provided in which the optical axis of the last lens and the central axis of the image sensor are arranged orthogonally. Embodiments provide a foldable optical system and a camera module having the same.

[0009] An optical system according to an embodiment includes a first reflective member; a second reflective member spaced apart from the first reflective member; a first lens group disposed between the first reflective member and an object; and a second lens group disposed between the first reflective member and the second reflective member, wherein the number of lenses of the first lens group is greater than the number of lenses of the second lens group, the first lens group has positive power, the second lens group has negative power, and a first lens among the lenses of the first lens group closest to the object may have positive power.

[0010] According to an embodiment of the invention, the first lens group includes second and third lenses sequentially aligned along a first optical axis from the first lens toward the first reflective member, and the second lens group includes fourth and fifth lenses sequentially aligned along a second optical axis orthogonal to the first optical axis between the first and second reflective members, wherein the fifth lens may have negative power.

[0011] According to an embodiment of the invention, the first lens group includes second and third lenses sequentially aligned along a first optical axis from the first lens toward the first reflective member, and the second lens group includes a fourth lens sequentially aligned along a second optical axis orthogonal to the first optical axis between the first and second reflective members, wherein the fourth lens may have negative power.

[0012] According to an embodiment of the invention, the last lens closest to the second reflective member may have negative power.

[0013] According to an embodiment of the invention, the effective diameter of the first lens may be the largest among the lenses of the first and second lens groups.

[0014] According to an embodiment of the invention, two or more of the lenses of the first and second lens groups may have a refractive index greater than 1.6.

[0015] According to an embodiment of the invention, the lenses adjacent to the first lens and the second lens may have a convex meniscus shape toward the object.

[0016] According to an embodiment of the invention, the second lens group is moved between the first and second reflective members, and the object-side surface of the last lens adjacent to the second reflective member may have a concave shape.

[0017] According to an embodiment of the invention, the optical axis distance of the first lens group is more than one time the optical axis distance of the second lens group, and the object-side surface of the last lens adjacent to the second reflective member may have a concave shape.

[0018] According to an embodiment of the invention, an image sensor is included that is arranged on the emission side of the second reflective member, and the image sensor can be arranged closer to the object side than the position of the second reflective member.

[0019] According to an embodiment of the invention, an image sensor is provided on the emission side of the second reflective member, and the image sensor can be provided on the opposite side of the object with respect to the second reflective member.

[0020] According to an embodiment of the invention, the first reflective member may be a prism, the second reflective member may be a prism, and the effective length of the second reflective member may be greater than the effective length of the first reflective member.

[0021] According to an embodiment of the invention, the first lens may be made of glass.

[0022] An embodiment of the invention provides an optical system having improved optical characteristics, comprising a plurality of reflective elements and a plurality of lenses. An autofocus (AF) function for a subject can be provided by moving a lens (or group of lenses) located on the object side of a first reflective element adjacent to the object or a lens (or group of lenses) located on the sensor side. Furthermore, optical image stabilization (OIS) can be adjusted using at least one of the first reflective element or the second reflective element.

[0023] The embodiment can have multiple lenses correct for aberration characteristics or mutually compensate for aberration characteristics that change with movement. Accordingly, the optical system according to the embodiment can minimize or prevent changes in chromatic aberration and aberration characteristics that occur when magnification changes.

[0024] The present invention provides a telescopic optical system capable of minimizing power consumption required depending on the operating mode. The optical system may include at least one lens, included in a fixed group and a moving group, having a non-circular shape. The embodiment may reduce the height of the optical system while maintaining optical performance. Furthermore, the optical system may provide an optical system with a large effective area of ​​a lens surface adjacent to an object, thereby suppressing an increase in the thickness of a portable device having a camera module.

[0025] An optical system according to an embodiment can have improved aberration characteristics and resolution by setting the surface shape, refractive power, thickness, and spacing between adjacent lenses of a plurality of lenses, and the focal length of each lens (group).

[0026] The optical system and camera module according to the embodiment may have improved distortion and aberration control characteristics and may have good optical performance at the center and periphery of the field of view (FOV).

[0027] FIG. 1 is a configuration diagram of an optical system and a camera module according to a first embodiment of the invention.

[0028] Figure 2 is a configuration diagram of the optical system in the near-field mode of Figure 1.

[0029] Fig. 3 is a table showing lens data of the optical system of Fig. 1.

[0030] Fig. 4 is a table showing the radius of curvature and conic constant of the lenses of the optical system of Fig. 1.

[0031] Fig. 5 is an example of changing the light path by the second reflective member of Fig. 2.

[0032] Figure 6 is a diagram illustrating the optical system of Figure 2.

[0033] Figures 7 (A) and (B) are graphs showing data of the diffraction MTF (Modulation Transfer Function) of the optical systems of Figures 1 and 2.

[0034] Fig. 8 is a graph showing the aberration characteristics of the optical system of Fig. 1.

[0035] Figure 9 is a graph showing the aberration characteristics of the optical system of Figure 2.

[0036] FIG. 10 is a graph showing relative illumination according to the field height of the image sensor in the optical system of FIGS. 1 and 2.

[0037] Fig. 11 is a configuration diagram of an optical system and a camera module according to a second embodiment of the invention.

[0038] Fig. 12 is a configuration diagram of the optical system in the near-distance mode of Fig. 11.

[0039] Fig. 13 is a table showing lens data of the optical system of Fig. 11.

[0040] Fig. 14 is an example of the radius of curvature, conic constant, and aspheric coefficient of the lenses of the optical system of Fig. 11.

[0041] (A)(B) of Fig. 15 are graphs showing data of the diffraction MTF (Modulation Transfer Function) of the optical system of Fig. 11 and Fig. 12.

[0042] Fig. 16 is a graph showing the aberration characteristics of the optical system of Fig. 11.

[0043] Fig. 17 is a graph showing the aberration characteristics of the optical system of Fig. 12.

[0044] Fig. 18 is a graph showing relative illumination according to the field height of the image sensor in the optical system of Figs. 11 and 12.

[0045] Figure 19 is a diagram showing the optical system of Figure 12 in development.

[0046] Fig. 20 is a perspective view of a mobile terminal to which a camera module according to an embodiment of the invention is applied.

[0047] FIG. 21 is a perspective view of a mobile device having a camera module according to an embodiment of the invention.

[0048] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. 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 belongs, unless explicitly and specifically defined and described, and terms that are commonly used, such as terms defined in a dictionary, can be interpreted in consideration of the contextual meaning of the related technology.

[0049] 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. 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 the 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” due to another component between the component and the other component. Additionally, when it is described as being formed or arranged "above or below" each component, "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. Furthermore, when it is expressed as "above" or "below", it can include the meaning of a downward direction as well as an upward direction based on one component.

[0050] In the description of the invention, the "object side surface" may mean a surface of the lens facing the object side based on the optical axis (OA), and the "sensor side surface" may mean a surface of the lens facing the imaging surface (image sensor) based on the optical axis. A convex surface of the lens may mean a convex shape in the optical axis or the paraxial region, and a concave surface of the lens may mean a concave shape in the optical axis or the paraxial region. The radius of curvature, center thickness, and gap between lenses described in the table for lens data mean values ​​in the optical axis, and the unit is mm. The vertical direction may mean a 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. The effective length of the lens surface may have a measurement error of up to ±0.4 mm depending on the measurement method, etc. The above-mentioned near-axis region refers to a very narrow region near the optical axis, and is a region where the distance a light ray falls from the optical axis (OA) is almost 0. Hereinafter, the concave or convex shape of the lens surface is described as the optical axis, and may also include the near-axis region.

[0051]

[0052] FIG. 1 and FIG. 11 are configuration diagrams of an optical system and a camera module according to embodiments of the invention.

[0053] Referring to FIGS. 1 and 11, the optical system (1000) or camera module may include a plurality of lenses and a plurality of reflective members (P1, P2). The plurality of lenses may include 6 or fewer lenses, for example, 3 to 6 lenses or 4 to 5 lenses. The optical system (1000) may have 4 or more or 6 or fewer lenses, excluding the reflective members (P1, P2). The plurality of reflective members (P1, P2) include a first reflective member (P1) and a second reflective member (P2) spaced apart from each other in a second optical axis direction (OA2). The second optical axis direction (OA2) is a direction passing through the centers of the first reflective member (P1) and the second reflective member (P2) facing each other.

[0054] The first reflective member (P1) reflects or refracts light incident along the first optical axis (OA1) in the direction of the second optical axis (OA2) orthogonal to the first optical axis (OA1). The second reflective member (P2) reflects or refracts light incident along the second optical axis (OA1) in the direction of the optical axis parallel to the first optical axis (OA1). The second reflective member (P2) can reflect or refract light incident along the second optical axis (OA2) toward the upper surface (Image surface) of the image sensor (190).

[0055]

[0056] The first reflective member (P1) may be a prism or a mirror, and may be provided as a prism, for example. The second reflective member (P2) may be a prism or a mirror. The optical system (1000) may be provided as a folded optical system. The number of lenses of the optical system (1000) may be six or less. The number of reflective members (P1, P2) in the optical system (1000) may be two to three.

[0057] The number of lenses arranged between the first reflective member (P1) and the object may be 4 or less, for example, 2 to 4. The lenses arranged between the first reflective member (P1) and the object may be a first lens group (LG1), and the number of lenses in the first lens group (LG1) may be 3. The number of lenses arranged between the first reflective member (P1) and the second reflective member (P2) may be 3 or less, for example, 1 to 3. The lens(es) arranged between the first reflective member (P1) and the second reflective member (P2) may be a second lens group (LG2), and the number of lenses in the second lens group (LG2) may be 1 or 2. The first lens group (LG1) may have a greater number of lenses than the number of lenses in the second lens group (LG2), for example, more than 1 time and less than 3 times.

[0058] The optical system (1000) can operate in a focusing mode from infinity to near distance by moving the first lens group (LG1) arranged between the first reflective member (P1) and the object or the second lens group (LG2) arranged between the first and second reflective members in the direction of the optical axis (OA). When the lens(es) arranged between the first and second reflective members (P1, P2) move in the direction of the second optical axis (OA2), one or more lenses can be moved.

[0059]

[0060] At least one or two of the lenses arranged between the first reflective member (P1) and the second reflective member (P2) may be provided with a structure in which one or both ends of the effective area are cut off. Here, the cut portion may be one or both ends of the lens in the first axis (OA1) direction. That is, one or both ends of the effective area of ​​a lens having a relatively long effective length may be cut off. Accordingly, the cut lens may have an effective length in the third direction (Z) that is shorter than an effective length in the second direction (Y). By reducing the effective lengths of the lenses arranged between the first reflective member (P1) and the second reflective member (P2) in the third direction, the height of the optical system (1000) and the camera module in the third direction (Z) can be reduced. The third direction (Z) is a direction orthogonal to the first and second directions (X, Y) and is a thickness direction of the portable device.

[0061]

[0062] The AF function can move at least one or both of the lenses between the first reflective member (P1) and the second reflective member (P2) in the direction of the second optical axis (OA2). Accordingly, the optical system can provide a foldable tele optical system. In addition, the OIS function can be implemented by tilting at least one of the first and second reflective members (P1, P2). As another example, the OIS function can be implemented by shifting a substrate having an image sensor (192). The lens or lens groups can be moved by a focusing drive unit having a magnet and a coil. The movement of the reflective member can be moved by an OIS drive unit having a magnet and a coil.

[0063]

[0064] The power of the first lens group (LG1) has a positive value. In addition, the power of the first lens (101, 111) closest to the object has a positive value. Accordingly, the first lens group (LG1) and the first lens (101, 111) can allow a larger amount of light to enter the entire area of ​​the incident surface (PS1) of the first reflective member (P1). The power of the second lens group (LG2) has a negative value. Since the power of the second lens group (LG2) is negative, the incident light can be refracted to the entire area of ​​the incident surface (PS3) of the second reflective member (P2). The power is the reciprocal of the focal length.

[0065] The power of the last lens (105, 114) closest to the image sensor (190) has a negative value. The last lens (105, 114) can refract incident light to the entire area of ​​the image sensor (190) through the second reflective member (P2). Accordingly, the resolution can be improved by utilizing the refractive power and power values ​​of each lens.

[0066]

[0067] The effective length of the first lens (101, 111) may be the largest among the lenses in the optical system (1000). Accordingly, the first lens (101, 111) may improve the amount of incident light. In addition, at least two of the lenses in the optical system (1000) may have a refractive index of 1.6 or higher. Accordingly, color dispersion by the lenses in the optical system (1000) may be controlled. The F number of the optical system (1000) may provide brightness of 2.0 or higher. The average refractive index of the second lens group (LG2) may be greater than the average refractive index of the first lens group (LG1). Accordingly, the resolution between the first and second reflective members (P1, P2) may be improved.

[0068] The object-side first surface (S1) of the first lens (101, 111) may have a convex shape toward the object. The convex first surface (S1) may increase the amount of incident light of the first lens group (LG1). The object-side seventh surface (S7) of the fourth lens (104, 114) closest to the first reflective member (P1) may have a convex or concave shape toward the object. Accordingly, the optical system (1000) may increase the amount of incident light, have good optical performance in the center and periphery of the field of view (FOV), and improve thermal compensation and chromatic aberration and distortion aberration.

[0069] The first lens (101, 111) may be made of plastic or glass. If the first lens (101, 111) is made of glass, deformation of the first lens (101, 111) due to external heat can be prevented. In addition, if the first lens (101, 111) is made of glass, external impact or damage to the lens surface can be prevented. In other words, the glass lens can block external exposure of the plastic lens and protect the lenses from external heat or impact.

[0070] Each of the plurality of lenses 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 an area having an effective diameter or effective length 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 end of the effective area may be defined as an edge or an end. The ineffective area may be an area through which effective light is not incident on the plurality of lenses. That is, the ineffective area may be an area unrelated to the optical characteristics. In addition, the end of the ineffective area may be an area fixed to a barrel (not shown) that accommodates the lens.

[0071]

[0072] The optical system (1000) may include an image sensor (190). The image sensor (190) may detect light and convert it into an electrical signal. The image sensor (190) may detect light that sequentially passes through the plurality of lenses (100). The image sensor (190) may be any one of a CCD (Charge Coupled Device), a CMOS (Complementary Metal Oxide Semiconductor), a CPD, and a CID, and may include an element that may detect incident light. The image sensor (190) may be an RGB (Red, Green, Blue) sensor for obtaining a color image. In addition, when the image sensors (190) are arranged in multiple numbers, the image sensors (190) may include an RGB image sensor and a black and white image sensor.

[0073] The diagonal length of the image sensor (190) may be greater than 4 mm, for example, greater than 4 mm and less than 12 mm, or in the range of 4 mm to 7 mm. Preferably, the diagonal length of the image sensor (190) may be longer than the effective length of the lenses arranged between the first and second reflective members.

[0074] The optical system (1000) may include an optical filter (192) disposed between the second reflective member (P2) and the image sensor (190). The optical filter (192) may be disposed between the last lens (105, 114) and the image sensor (190). The optical filter (192) may be disposed between the lens closest to the sensor side among the plurality of lenses and the image sensor (190).

[0075] The optical filter (192) may include at least one of an infrared filter and a cover glass. The optical filter (192) may allow light of a set wavelength band to pass through and filter light of a different wavelength band. When the optical filter (192) includes an infrared filter, it may block radiant heat emitted from external light from being transmitted to the image sensor (190). The optical filter (192) may transmit visible light and reflect infrared light. A cover glass (not shown) may be included between the optical filter (192) and the image sensor (190). The cover glass may protect the image sensor (190). The camera module may be a camera for capturing RGB images or a camera for capturing RGB images and infrared images.

[0076]

[0077] The optical system (1000) according to the embodiment may include an aperture stop (ST). The aperture (ST) may be a stopper that controls the amount of light incident on the optical system (1000). For example, the aperture (ST) may be arranged around the object-side surface or the sensor-side surface of the fourth lens (104, 114).

[0078] The field of view (FOV) of the optical system (1000) may be less than or equal to 100 degrees, for example, more than 10 degrees, for example, in the range of 11 to 50 degrees, for example, in the range of 11 to 40 degrees. The F number (F#) of the optical system (1000) may be greater than 2.5, for example, in the range of 2.5 < F# < 5, and may provide a bright image. In addition, the F# may be smaller than the entrance pupil size (EPD). Therefore, the optical system (1000) may have a slim size, control incident light, and have improved optical characteristics within the field of view range.

[0079]

[0080] Hereinafter, the optical system according to the embodiments will be described in detail. FIGS. 1 to 10 are drawings explaining the optical system of the first embodiment.

[0081] Referring to FIGS. 1 to 4, in the first embodiment of the invention, the optical system (1000) may include a first lens (101) to a third lens (103), a first reflective member (P1), fourth and fifth lenses (104, 105), and a second reflective member (P2) arranged from an object toward a sensor.

[0082] The lenses arranged on the object side of the first reflective member (P1) may be defined as a first lens group (LG1). The lenses arranged between the first reflective member (P1) and the second reflective member (P2) may be defined as a second lens group (LG2). The number of lenses in the first lens group (LG1) may be 2 to 4, for example, 3. The number of lenses in the second lens group (LG2) may be 3 or less, for example, 1 to 3, or 2. The optical system (1000) may have 6 or less, for example, 5.

[0083] The first lens (101) to the third lens (103) are sequentially arranged along the first optical axis (OA1) between the object and the first reflective member (P1), and the fourth and fifth lenses (104, 105) are sequentially arranged along the second optical axis (OA2) between the first reflective member (P1) and the second reflective member (P2).

[0084] The first to third lenses (101, 102, 103) may be defined as a first lens group (LG1), and the fourth and fifth lenses (104, 105) may be defined as a second lens group (LG2). Each of the first to fifth lenses (101-105) may have an object-side surface and a sensor-side surface. The object-side surface is the incident-side surface of the lens, and the sensor-side surface is the output-side surface of the lens.

[0085] Each lens surface (S1-S10) of the first to fifth lenses (101-105) may be a spherical surface. As shown in Fig. 4, each lens surface (S1-S10) of the first to fifth lenses (101-105) represents a radius of curvature (R) and a conic constant (K). In Fig. 4, L1 to L5 represent the first to fifth lenses.

[0086] The refractive power of the first lens group (LG1) may have a positive value, and the refractive power of the second lens group (LG2) may have a negative value. The refractive power of the first lens group (LG1) is FLG1, and the refractive power of the second lens group (LG2) is FLG2, and the condition: FLG1 < |FLG2| may be satisfied. The position of the first lens group (LG1) may be fixed depending on the operation mode, and the position of the second lens group (LG2) may be variable depending on the operation mode.

[0087]

[0088] The first lens (101) may have positive (+) or negative (-) refractive power on the first optical axis (OA1), and preferably may have positive (+) refractive power. The first lens (101) may include a plastic or glass material, and preferably may be a glass material.

[0089] On the first optical axis (OA1), the first surface (S1) on the object side of the first lens (101) may have a convex shape, and the second surface (S2) on the sensor side may have a concave shape. That is, the first lens (101) may have a meniscus shape that is convex toward the object on the first optical axis (OA1). Since the first lens (101) has a meniscus shape that is convex toward the object side, the amount of incident light may be improved. At least one or both of the first surface (S1) and the second surface (S2) may be spherical. Alternatively, the first lens (101) may have a meniscus shape that is convex toward the first reflective member (P1). Alternatively, the first lens (101) may have a convex shape on both sides. Alternatively, the first lens (101) may have a concave shape on both sides.

[0090] The effective length (clear aperture) of the first lens (101) may be the largest among the effective lengths of the first to fifth lenses (101-105). The first surface (S1) of the first lens (101) may be the largest among the lens surfaces (S1-S10) of the first to fifth lenses (101-105), and may improve the amount of incident light of the first lens (101). The effective length of the first lens (101) is the length or diameter of the effective area, and is twice the semi-aperture. The effective length of each lens is the average of the effective lengths of the object-side surface and the sensor-side surface of each lens.

[0091]

[0092] The second lens (102) may have positive (+) or negative (-) refractive power on the first optical axis (OA1). The second lens (102) may have negative (-) refractive power. The second lens (102) may correct aberrations occurring in the first lens (101). The second lens (102) may include a plastic or glass material, and may be provided as a glass material, for example. The object-side third surface (S3) of the second lens (102) on the first optical axis (OA1) may have a convex shape, and the sensor-side fourth surface (S4) may have a concave shape. That is, the second lens (102) may have a convex meniscus shape toward the object on the second optical axis (OA). Alternatively, the third surface (S3) may have a convex shape on the second optical axis (OA2), and the fourth surface (S4) may have a convex shape. Alternatively, the third and fourth surfaces (S3, S4) may both have concave shapes. Alternatively, the second lens (102) may have a convex meniscus shape toward the first reflective member (P1).

[0093] At least one or both of the third surface (S3) and the fourth surface (S4) of the second lens (102) may be spherical. The center distance between the first lens (101) and the second lens (102) is 0.5 mm or less, for example, in the range of 0.1 mm to 0.5 mm. This can reduce the loss of light passing through the first and second lenses (101, 102) and suppress an increase in the optical axis distance (TD1) of the first lens group (LG1).

[0094]

[0095] The third lens (103) may have positive (+) or negative (-) refractive power on the second optical axis (OA2), and preferably may have positive (+) refractive power. The third lens (103) may include a plastic or glass material, and may be, for example, a glass material.

[0096] On the second optical axis (OA2), the object-side fifth surface (S5) of the third lens (103) may have a concave shape, and the sensor-side sixth surface (S6) may have a convex shape. That is, the third lens (103) may have a meniscus shape convex toward the first reflective member (P1) on the first optical axis (OA1). Alternatively, the third lens (103) may have a convex shape on both sides. Alternatively, the fifth and sixth surfaces (S5, S6) may both have concave shapes. Alternatively, the third lens (103) may have a meniscus shape convex toward the object. At least one or both of the fifth surface (S5) and the sixth surface (S6) of the third lens (103) may be spherical.

[0097] The center spacing between the second and third lenses (102, 103) may be greater than the sum of the center spacing between the first and second lenses (101, 102) and the center spacing between the third lens (103) and the first reflective member (P1).

[0098]

[0099] The first reflective member (P1) is disposed between the third lens (103) and the fourth lens (104). The first reflective member (P1) is disposed between the sixth surface (S6) of the third lens (103) and the seventh surface (S7) of the fourth lens (104). The first reflective member (P1) reflects or refracts light incident on the first optical axis (OA1) toward the second optical axis (OA2) orthogonal to the first optical axis (OA1). The first reflective member (P1) has a triangular prism shape and may be provided with a glass material or a plastic material. The optical axes (OA) of the lenses can be divided into first and second optical axes (OA1, OA2) that are orthogonal to each other.

[0100] The first reflective member (P1) includes an incident surface (PS1), a reflective surface (PR1), and an exit surface (PS2), and the incident surface (PS1) faces the third lens (103), and the exit surface (PS2) faces the fourth lens (104). The center distance (MG1) between the incident surface (PS1) of the first reflective member (P1) and the third lens (103) may be smaller than the center distance between the first and second lenses (101, 102).

[0101]

[0102] As shown in FIGS. 1 and 2, the center distance (D1) between the first reflective member (P1) and the fourth lens (104) can be varied by the second lens group (LG2). The second lens group (LG2) can be moved from infinity to a near mode, and the near mode can be 50 cm. When infinity, the center distance (D1) between the first reflective member (P1) and the fourth lens (104) can be smaller than the center thickness of the first lens (101), and can be, for example, larger than the center distance (MG1). When in the near mode, the center distance (D1) between the first reflective member (P1) and the fourth lens (104) can be increased from the distance in the infinity mode, and can be larger than the center thickness of the first lens (101). The above-mentioned center spacing (D1) may be 0.2 mm or more, and may range from 0.2 mm to 2 mm. The movement distance of the second lens group (LG2) may be 0.5 mm or more, and may range from 0.5 mm to 1.5 mm, for example. Accordingly, an optical system capable of both a close-up mode and an infinity mode can be provided.

[0103] The fourth lens (104) may have positive (+) or negative (-) refractive power on the second optical axis (OA2). The fourth lens (104) may have positive (+) refractive power. The fourth lens (104) may include a plastic or glass material. For example, the fourth lens (104) may be provided as a glass material.

[0104] On the second optical axis (OA2), the object-side seventh surface (S7) of the fourth lens (104) may have a concave shape, and the sensor-side eighth surface (S8) may have a convex shape. That is, the fourth lens (104) may have a convex meniscus shape toward the second reflective member (P2) on the second optical axis (OA2). Alternatively, the fourth lens (104) may have a convex shape on both sides. Alternatively, the fourth lens (104) may have a convex meniscus shape toward the first reflective member (P1). Alternatively, the fourth lens (104) may have a concave shape on both sides. At least one or both of the seventh surface (S7) and the eighth surface (S8) may be spherical.

[0105] The center distance between the third lens (103) and the fourth lens (104) is 0.5 mm or less, which can reduce the loss of light passing through the third and fourth lenses (103, 104) and reduce the optical axis distance (TD2) of the second lens group (LG2).

[0106]

[0107] The fifth lens (105) may have positive (+) or negative (-) refractive power on the second optical axis (OA2). The fifth lens (105) is the nth lens and may have negative refractive power. The fifth lens (105) may include a plastic or glass material. For example, the fifth lens (105) may be provided as a glass material. Since the signs of the refractive powers of the fourth and fifth lenses (104, 105) are opposite to each other, chromatic aberrations occurring in the two lenses can be mutually compensated.

[0108] The object-side ninth surface (S9) of the fifth lens (105) on the second optical axis (OA2) may have a concave shape, and the sensor-side tenth surface (S10) may have a concave shape. That is, the fifth lens (105) may have a concave shape on both sides on the second optical axis (OA2). Alternatively, the fifth lens (105) may have a convex meniscus shape toward the object. Alternatively, the fifth lens (105) may have a convex meniscus shape toward the second reflective member (P2). Alternatively, the fifth lens (105) may have a convex shape on both sides. At least one or both of the ninth surface (S9) and the tenth surface (S10) of the fifth lens (105) may be spherical.

[0109] The fifth lens (105) provides light to the entire area of ​​the incident surface (PS3) of the second reflective member (P2), and the light reflected by the reflective surface (PR2) of the second reflective member (P2) can be irradiated to the center and periphery of the image sensor (190). Therefore, the optical system (1000) according to the embodiment can have improved optical characteristics even in the center and periphery of the field of view (FOV). As another example, at least one or all of the first to fifth lenses (101-105) may be provided as a plastic material or as an aspherical lens. For example, the second, third, fourth, and fifth lenses may be aspherical lenses made of a plastic material.

[0110] The first lens (101) may have the maximum effective length among the lenses. The first surface (S1) of the first lens (101) may be the largest among the lens surfaces. The third lens (103) may have the minimum effective length among the lenses. For example, the effective length of the sixth surface (S6) of the third lens (103) may be the smallest among the lens surfaces. The maximum effective length of the lenses may be more than 1 time, for example, more than 1 time and less than 2 times, the minimum effective length. The first surface (S1) of the first lens (101) may be 1.2 times or more, for example, in the range of 1.2 to 2 times, the effective length of the sixth surface (S6) of the third lens (103).

[0111]

[0112] The second reflective member (P2) may be a prism or a mirror, for example, a prism. The second reflective member (P2) has an incident surface (PS3), a reflective surface (PR2), and an exit surface (PS4), and the reflective surface (PR2) may be inclined at an angle of 45 degrees with respect to a second optical axis (OA2). The second reflective member (P2) may reflect incident light toward an object. The light reflected through the second reflective member (P2) is incident on the entire area of ​​the image sensor (190) through the optical filter (192). A central axis passing through the optical filter (192) and the image sensor (190) may be parallel to the first optical axis (OA1). The optical filter (192) and the image sensor (190) are disposed at a position further away from the object with respect to the second optical axis (OA2).

[0113] The optical axis distance (D2) between the incident surface (PS3) of the second reflective member (P2) and the fifth lens (105) can be varied according to the movement of the fourth and fifth lenses (104, 105). In infinity mode, the condition: D1 < D2 can be satisfied, and in near-distance mode, the condition: D1 > D2 can be satisfied.

[0114]

[0115] The center thickness and edge thickness of the above lenses are as follows. The center thickness of the first to fifth lenses (101-105) is CT1-CT5, the edge thickness is ET1-ET5, and the optical axis distance between the image sensor (190) and the sensor-side surface (S10) of the last lens (105) is BFL (Back focal length), and the following condition can be satisfied. Here, the edge thickness of each lens can be the distance in the optical axis direction between the effective areas of each lens.

[0116] Condition 1: CT2 < CT1

[0117] Condition 2: CT3 < CT1

[0118] Condition 3: CT4 < ET4

[0119] Condition 4: CT4+CT5 < CT1

[0120] Condition 5: ET1 < CT2 < ET2 < CT1

[0121] Condition 6: ET4 < ET3 < ET1 < ET2 < ET5 < CT1

[0122] Condition 7: (CT1+CT2+CT3+CT4+CT5) < BFL

[0123] By setting the center thickness and edge thickness of the above lenses, the optical system (1000) can control the incident light and have improved aberration characteristics and resolution.

[0124] The center distance between the third lens (103) and the first reflective member (P1) is MG1, and the conditions: MG1 < D1 and MG1 < D2 can be satisfied. In addition, the condition: MG1 < CT3 can be satisfied.

[0125] The center distance between the fourth lens (104) and the first reflective member (P1) is D1, and the center distance (D1) can be varied by movement of the second lens group (LG2) in the direction of the second optical axis (OA2), and can be moved in a range of 0.4 mm or more, for example, 0.4 mm to 2.4 mm. Since the second lens group (LG2) is moved, an object from a long distance (e.g., infinity) to a short distance (e.g., 50 cm) can be imaged. The center distance (D1) may be larger than the center distance between the fourth and fifth lenses (104, 105) in the infinity mode, and may be larger than the optical axis distance of the fourth and fifth lenses (104, 105) in the short distance mode. The optical axis distance of the fourth and fifth lenses (104, 105) is the optical axis distance of the second lens group (LG2) and can be defined as TD2.

[0126] By moving the second lens group (LG2), the center distance (D2) between the area of ​​the fifth lens (105) and the second reflective member (P2) can satisfy TD2 < D2 in infinity mode and satisfy the condition: D2 < D6 in near mode.

[0127]

[0128] The radii of curvature of the above lenses are as follows.

[0129] On the first optical axis (OA1) or the vertex of each lens surface, the radii of curvature of the first and second surfaces (S1, S2) of the first lens (101) are L1R1, L1R2, the radii of curvature of the third and fourth surfaces (S3, S4) of the second lens (102) are L2R1, L2R2, and the radii of curvature of the fifth and sixth surfaces (S5, S6) of the third lens (103) are L3R1, L3R2. On the second optical axis (OA2) or the vertex of each lens surface, the radii of curvature of the seventh and eighth surfaces (S7, S8) of the fourth lens (104) are L4R1, L4R2, and the radii of curvature of the ninth and tenth surfaces (S9, S10) of the fifth lens (105) can be defined as L5R1, L5R2. The above curvature radii can satisfy at least one of the following conditions to improve the aberration characteristics of the optical system.

[0130] Condition 1: L1R1 < L1R2

[0131] Condition 2: L2R2 < L2R2 < L1R2

[0132] Condition 3: |L3R2| < L1R2 < |L3R1|

[0133] Condition 4: |L4R2|*2 < L4R1 < |L3R1|

[0134] Condition 5: 0.5 < |L4R2 / L5R1| < 1.5

[0135] Condition 6: |L3R1|< L5R2

[0136] In the absolute values ​​of the radius of curvature of each lens surface, the tenth surface (S10) of the fifth lens (105) may be the largest among the lens surfaces, and the fourth surface (S4) of the second lens (102) may be the smallest among the lens surfaces. By setting the radius of curvature of each lens, good optical performance can be provided at the focal length of each lens.

[0137]

[0138] The effective length (clear aperture) of the first to fifth lenses (101-105) may be defined as CA1-CA5, and the effective length (CA1) of the first lens (101) may have the maximum effective length among the lenses and may be 5 mm or more. The effective length (CA3) of the third lens (103) may be the minimum among the lenses. The effective lengths of the first and second surfaces (S1, S2) of the first lens (101) can be defined as CA11, CA12, the effective lengths of the third and fourth surfaces (S3, S4) of the second lens (102) can be defined as CA21, CA22, the effective lengths of the fifth and sixth surfaces (S5, S6) of the third lens (103) can be defined as CA31, CA32, the effective lengths of the seventh and eighth surfaces (S7, S8) of the fourth lens (104) can be defined as CA41, CA42, and the effective lengths of the ninth and tenth surfaces (S9, S10) of the fifth lens (105) can be defined as CA51, CA52. These effective lengths are factors that affect the aberration characteristics of the optical system and can satisfy at least one of the following conditions.

[0139] Condition 1: CA3 < CA5 < CA2 < CA1

[0140] Condition 2: 0.5 < CA4 / CA5 < 1.5

[0141] Condition 3: CA22 < CA12 < CA11

[0142] Condition 4: CA32 < CA22 < CA12

[0143] Condition 5: CA32 < CA51 < CA22

[0144] The effective length (CA11) of the first surface (S1) of the first lens (101) may be provided as the largest within the optical system, thereby increasing the amount of incident light. The number of lenses among the first to sixth lenses (101-105) having an effective length smaller than the diagonal length of the image sensor (190) may be three or more. For example, the effective lengths of the second to fifth lenses (102-105) may be smaller than the diagonal length of the image sensor (190). The effective lengths of the third to tenth surfaces (S3-S10) may be smaller than the effective diagonal length of the image sensor (190). The difference between the minimum effective length and the maximum effective length among the lens surfaces may be 1 mm or more, for example, in the range of 1 mm to 3 mm. For example, the effective length of the second to tenth surfaces (S2-S8) may be smaller than the effective diagonal length of the image sensor (190). The effective length of the first lens (111) may be larger than the diagonal length of the image sensor (190).

[0145]

[0146] The number of lenses having a refractive index exceeding 1.6 of the above lenses may be two or more, for example, the refractive indices of the second, fourth, and fifth lenses (102, 104, and 105) may be greater than 1.6. The number of lenses having a refractive index less than 1.6 of the above lenses may be two or less. In the optical system, the number of lenses having an Abbe number exceeding 45 may be two or more, for example, the first and third lenses (101, 103). By setting the refractive index and Abbe number of each of these lenses, the influence of chromatic aberration can be controlled.

[0147] When the refractive index of each lens (101-105) is Nd1, Nd2, Nd3, Nd4, Nd5, and the Abbe number of each lens (101-105) is Vd1, Vd2, Vd3, Vd4, Vd5, at least one of the following conditions can be satisfied.

[0148] Condition 1: Nd1 < Nd2

[0149] Condition 2: 1.5 < Nd1, Nd3 < 1.6

[0150] Condition 3: 1.6 < Nd2, Nd4, Nd6 < 2.0

[0151] Condition 4: Vd2 < Vd1,Vd3

[0152] Condition 5: Vd4 < Vd5 < 30

[0153] Depending on the refractive index and Abbe number, the optical system (1000) can have improved chromatic aberration control characteristics.

[0154] When the focal length of each lens (101-105) is defined as F1, F2, F3, F4, F5, the following conditions can be satisfied.

[0155] Condition 1: F1 < |F2|

[0156] Condition 2: F1 < F3

[0157] Condition 3: F1+|F2| < F3

[0158] Condition 4: |F5| < F4 < F1

[0159] Among the absolute values ​​of the focal lengths of the lenses, the largest lens is the third lens (103), and can satisfy a range of 35 mm or more, for example, a range of 35 mm to 70 mm or a range of 35 mm to 65 mm.

[0160]

[0161] In Fig. 1, the height of the optical system (1000) is the sum of the first optical axis distance (T1) from the center of the object-side surface (S1) of the first lens (101) to the center of the reflective surface (PR1) of the first reflective member (P1) and the distance from the center of the reflective surface (PR1) of the first reflective member (P1) to the lower end of the first reflective member (P1) or the second reflective member (P2). The height of the optical system (1000) is less than twice the first optical axis distance (T1). A third optical axis distance (T3) from the reflective surface (PR2) of the second reflective member (P2) to the center of the image sensor (190) may be smaller than the first optical axis distance (T1).

[0162] The second optical axis distance (T2) from the reflective surface (PR1) of the first reflective member (P1) to the reflective surface (PR2) of the second reflective member (P2) may affect the length of the optical system (1000) in the first direction (X). The total length (TTL) of the optical system (1000) is the length of the first and second optical axes (OA1, OA2) from the center of the object-side surface (S1) of the first lens (101) to the image sensor (192), which is the sum of the first, second, and third optical axis distances (T1, T2, T3). Since the image sensor (190) is arranged parallel to the first direction (X), the image sensor (190) and the first reflective member (P1) may not overlap in the first direction (X).

[0163] As shown in Fig. 5, the second reflective member (P2) can reflect the incident light toward the opposite side of the object. Accordingly, the optical filter (192) and the image sensor (190) can be spaced further apart than the second reflective member (P2). Since the optical filter (192) and the image sensor (190) are arranged in the opposite side of the object side of the second reflective member (P2), the height of the optical system in the third direction (Z) can increase. As another example, the second reflective member (P2) can have a 43 degree inclination angle of the reflective surface (PR2), in which case the height of the optical system can be reduced.

[0164] As shown in Fig. 6, the fourth and fifth lenses (104, 105) can be moved in the direction of the optical axis (OA) between the first and second reflective members (P1, P2), and the first to third lenses (101, 102, 103) arranged on the object side of the first reflective member (P1) can be fixed in position. In the direction orthogonal to the optical axis (OA), the effective length of the second reflective member (P2) can be greater than the effective length of the first reflective member (P1). Accordingly, even if at least one or both of the fourth and fifth lenses (104, 105) are moved, light loss can be reduced.

[0165]

[0166] (A)(B) of FIG. 7 are graphs showing the diffraction MTF (Modulation Transfer Function) in the optical systems of FIG. 1 and FIG. 2, and are graphs showing the modulation ratio according to the spatial frequency. FIG. 8 is a graph showing the aberration characteristics of the optical system of FIG. 1, and FIG. 9 is a graph showing the aberration characteristics of the optical system of FIG. 2. Referring to FIG. 8 and FIG. 9, these are graphs measuring spherical aberration (Longitudinal Spherical Aberration), astigmatic field curves, and distortion from left to right in the aberration graphs of the optical system. 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. Additionally, the graph for spherical aberration is a graph for light in the wavelength bands of about 470 nm, about 555 nm, about 610 nm, and about 650 nm, and the graph for astigmatism and distortion is a graph for light in the wavelength band of 555 nm.

[0167] Fig. 10 is a graph showing relative illumination according to the relative sensor height (relative Fielded height) of the optical system of Figs. 1 and 2. As shown in Fig. 10, it can be seen that the relative illumination is the highest in the center (0.0) field (Field) of the image sensor and also shows 90% or more in the end (1.0) field. The optical system (1000) according to the embodiment has improved resolution and can have good optical performance not only in the center but also in the periphery of the field of view (FOV). The lens system according to the embodiment of the present invention can have a configuration of 7 or fewer lenses, for example, 6 lenses, so that spherical aberration, astigmatism, distortion aberration, chromatic aberration, and coma aberration can all be well corrected.

[0168]

[0169] Figures 11 to 19 are drawings illustrating a second embodiment. In describing the second embodiment, the same configuration as the first embodiment may include the configuration and description of the first embodiment.

[0170] Referring to FIGS. 11 to 14, an optical system (1000) according to a second embodiment of the invention may include a first lens (111) to a third lens (113), a first reflective member (P1), a fourth lens (114), and a second reflective member (P2) arranged from an object toward a sensor.

[0171] The first, second, and third lenses (111, 112, and 113) are arranged on the object side of the first reflective member (P1) and may be defined as a first lens group (LG1). The fourth lens (114) is arranged between the first and second reflective members (P1, P2) and may be defined as a second lens group (LG2). The number of lenses in the first lens group (LG1) may be more than 1 and less than or equal to 4, for example, 3. The number of lenses in the second lens group (LG2) may be less than or equal to 2, for example, 1. The optical system (1000) may be less than or equal to 5, for example, 4.

[0172] The first lens (111) to the third lens (113) are sequentially arranged along the first optical axis (OA1) between the object and the first reflective member (P1), and the fourth lens (114) is arranged along the second optical axis (OA2) between the first reflective member (P1) and the second reflective member (P2). Each of the first to fourth lenses (111-114) may have an object-side surface and a sensor-side surface. The refractive power (FLG1) of the first lens group (LG1) may have a positive value, and the refractive power (FLG2) of the second lens group (LG2) may have a negative value, and the condition: FLG1 < |FLG2| may be satisfied. The first lens group (LG1) may be fixed in position according to the operation mode, and the second lens group (LG2) may have a variable position according to the operation mode.

[0173]

[0174] The first lens (111) may have positive (+) refractive power on the first optical axis (OA1). The first lens (111) may include a plastic or glass material, and may be made of, for example, glass. The object-side first surface (S1) of the first lens (111) on the first optical axis (OA1) may have a convex shape, and the sensor-side second surface (S2) may have a concave shape. That is, the first lens (111) may have a convex meniscus shape toward the object on the first optical axis (OA1). Since the first lens (111) has a convex meniscus shape toward the object, the amount of incident light may be improved. At least one or both of the first surface (S1) and the second surface (S2) may be spherical. The effective length of the first lens (111) may be the largest among the effective lengths of the first to fourth lenses (111-114). The first surface (S1) of the first lens (111) may be the largest among the lens surfaces (S1-S8) of the first to fourth lenses (111-114). Accordingly, the amount of incident light of the first lens (111) may be improved.

[0175] The second lens (112) may have a negative refractive power on the first optical axis (OA1). The second lens (112) may correct aberrations occurring in the first lens (111). The second lens (112) may be provided with a plastic material. The object-side third surface (S3) of the second lens (112) on the first optical axis (OA1) may have a convex shape, and the sensor-side fourth surface (S4) may have a concave shape. At least one or both of the third surface (S3) and the fourth surface (S4) of the second lens (112) may be aspherical. The aspherical coefficients of the third surface (S3) and the fourth surface (S4) of the second lens (112) are provided as shown in FIG. 14, and L2 represents the second lens (112) and represents the conic constant (K) and aspherical coefficients from the 4th to the 10th order. The center spacing between the first lens (111) and the second lens (112) is 0.5 mm or less, for example, in the range of 0.1 mm to 0.5 mm.

[0176]

[0177] The third lens (113) may have a negative refractive power on the second optical axis (OA2). The third lens (113) may include a plastic or glass material, and may be, for example, a plastic material. The object-side fifth surface (S5) of the third lens (113) on the second optical axis (OA2) may have a concave shape, and the sensor-side sixth surface (S6) may have a convex shape. That is, the third lens (113) may have a convex meniscus shape toward the first reflective member (P1) on the first optical axis (OA1). At least one or both of the fifth surface (S5) and the sixth surface (S6) of the third lens (103) may be aspherical. As shown in Fig. 14, L3 is a third lens (113), and represents the conic constant (K) and aspherical coefficients from the 4th to the 10th order. Alternatively, the third lens (113) may have a convex shape on both sides. Alternatively, the fifth and sixth surfaces (S5, S6) may both have concave shapes. Alternatively, the third lens (113) may have a meniscus shape that is convex toward the object.

[0178] The center spacing between the second and third lenses (112, 113) may be greater than the sum of the center spacing between the first and second lenses (111, 112) and the center spacing between the third lens (113) and the first reflective member (P1). The center thickness of the third lens (113) may be the largest among the lenses. Accordingly, the third lens (113) may provide incident light to the entire area of ​​the first reflective member (P1).

[0179]

[0180] The first reflective member (P1) reflects or refracts light incident on the first optical axis (OA1) through the first lens group (LG1) in the direction of the second optical axis (OA2) orthogonal to the first optical axis (OA1). The first reflective member (P1) has a triangular prism shape and may be provided with a glass material or a plastic material. The incident surface (PS1) of the first reflective member (P1) faces the third lens (113), and the exit surface (PS2) faces the fourth lens (114). The center distance (MG1) between the incident surface (PS1) of the first reflective member (P1) and the third lens (113) may be greater than the center distance between the first and second lenses (111, 112).

[0181]

[0182] As shown in FIGS. 11 and 12, the center distance (D1) between the first reflective member (P1) and the fourth lens (114) can be varied by the second lens group (LG2). The second lens group (LG2) can be moved from infinity to a near mode, and the near mode can be 50 cm. In the infinity mode, the center distance (D1) between the first reflective member (P1) and the fourth lens (114) can be greater than the center thickness of the first lens (111), for example, can be smaller than the center thickness of the first lens (111). In the near mode, the center distance (D1) between the first reflective member (P1) and the fourth lens (113) can be greater than the distance in the infinity mode, and can be greater than the center thickness of the first lens (111). The above-mentioned center distance (D1) may be 0.2 mm or more, and may range from 0.2 mm to 3 mm. The movement distance of the second lens group (LG2) may be 0.5 mm or more, and may range from 0.5 mm to 1.5 mm, for example. Accordingly, an optical system capable of both a close-up mode and an infinity mode can be provided.

[0183] The fourth lens (114) may have a negative refractive power on the second optical axis (OA2). The fourth lens (114) may be provided with a plastic material. The object-side seventh surface (S7) of the fourth lens (114) on the second optical axis (OA2) may have a concave shape, and the sensor-side eighth surface (S8) may have a convex shape. That is, the fourth lens (114) may have a convex meniscus shape toward the second reflective member (P2) on the second optical axis (OA2). At least one or both of the seventh surface (S7) and the eighth surface (S8) may be aspherical, and the conic constant (K) and the aspherical coefficients from the 4th to the 12th order are provided as shown in FIG. 14, and L4 is the fourth lens (114). The central thickness of the fourth lens (114) is the optical axis distance (TD2) of the second lens group (LG2), and by reducing the number of lenses of the second lens group (LG2), the second optical axis distance (T2) can be reduced. The central thickness of the second and fourth lenses (112, 114) may be less than 1 mm, and for example, may be more than 0.3 mm and less than 1 mm.

[0184]

[0185] The second reflective member (P2) may be a prism or a mirror, for example, a prism. The second reflective member (P2) has an incident surface (PS3), a reflective surface (PR2), and an exit surface (PS4), and the reflective surface (PR2) may be inclined at an angle of 45 degrees with respect to the second optical axis (OA2). Light reflected through the second reflective member (P2) is incident on the entire area of ​​the image sensor (190) through the optical filter (192). A central axis passing through the optical filter (192) and the image sensor (190) may be parallel to the first optical axis (OA1). The optical filter (192) and the image sensor (190) are arranged at a position further away from the object with respect to the second optical axis (OA2).

[0186] The optical axis distance (D2) between the incident surface (PS3) of the second reflective member (P2) and the fourth lens (115) can be varied according to the movement of the fourth lens (114). In infinity mode, the condition: D1 < D2 can be satisfied, and in short-distance mode, the condition: D1 > D2 can be satisfied.

[0187] The center thickness and edge thickness of the above lenses are as follows.

[0188] Condition 1: CT2 < CT1

[0189] Condition 2: CT1 < CT3

[0190] Condition 3; CT4 < CT1

[0191] Condition 4: CT3 < ET3

[0192] Condition 5: ET1 < CT2 < CT1

[0193] Condition 6: 0.5 < CT2 / CT4 < 1.5

[0194] Condition 7: 0.5 < ET2 / ET4 < 1.5

[0195] Condition 8: (CT3+CT1) < BFL

[0196] The center distance between the third lens (113) and the first reflective member (P1) is D1, and the distance (D1) can be varied by movement of the second lens group (LG2) in the direction of the second optical axis (OA2), and can be moved in a range of 0.4 mm or more, for example, 0.4 mm to 2.4 mm. Since the second lens group (LG2) is moved, an object from a long distance (e.g., infinity) to a short distance (e.g., 50 cm) can be imaged. The distance (D1) is such that when in the infinity mode, the fourth lens (114) is positioned closer to the first reflective member (P1) than to the second reflective member (P2), and when in the short distance mode, the fourth lens (114) is positioned closer to the second reflective member (P2) than to the first reflective member (P1).

[0197]

[0198] The radii of curvature of the above lenses are as follows. The radii of curvature may satisfy at least one of the following conditions to improve the aberration characteristics of the optical system.

[0199] Condition 1: L1R1 < L1R2

[0200] Condition 2: L2R1 < L1R1 < |L3R1|

[0201] Condition 3: |L3R1| < |L3R2| < L1R2

[0202] Condition 4: |L3R2|*10 < L1R2

[0203] Condition 5: 5 < |L4R1| / L4R2 < 15

[0204] Condition 6: L1R2 < |L4R1|

[0205] In the absolute values ​​of the radius of curvature of each lens surface, the eighth surface (S8) of the fourth lens (114) may be the largest among the lens surfaces, and the fourth surface (S4) of the second lens (112) may be the smallest among the lens surfaces. By setting the radius of curvature of each lens, good optical performance can be provided at the focal length of each lens.

[0206] The effective lengths (CA11, CA12, CA21, CA22, CA31, CA32) of the lens surfaces of the first to third lenses (111, 112, 113) and the effective lengths (CA41, CA42) of the lens surfaces of the fourth lens (114) are factors that affect the aberration characteristics of the optical system and can satisfy at least one of the following conditions.

[0207] Condition 1: CA3 < CA4 < CA2 < CA1

[0208] Condition 2: 0.5 < CA5 / CA6 < 1.5

[0209] Condition 3: CA22 < CA21 < CA11

[0210] Condition 4: CA32 < CA31 < CA22

[0211] Condition 5: CA41 < CA42 < CA21 < CA12

[0212] The effective length (CA11) of the first surface (S1) of the first lens (111) is provided as the largest within the optical system, thereby increasing the amount of incident light. The difference between the minimum effective length and the maximum effective length among the lens surfaces may be 1 mm or more, for example, in the range of 1 mm to 3 mm.

[0213] Among the first to fourth lenses (111-114), the number of lenses having an effective length smaller than the diagonal length of the image sensor (190) may be three or less. For example, the effective lengths of the second to fourth lenses (112-114) may be smaller than the diagonal length of the image sensor (190). For example, the effective lengths of the second to eighth surfaces (S2-S8) may be smaller than the effective diagonal length of the image sensor (190). The effective length of the first lens (111) may be larger than the diagonal length of the image sensor (190).

[0214]

[0215] The number of lenses having a refractive index exceeding 1.6 of the above lenses may be 2 or less, and the number of lenses having a refractive index less than 1.6 may be 1 or more. Within the lenses, the second and fourth lenses (112, 114) have a refractive index exceeding 1.60 and can refract incident light to the entire area of ​​the first and second reflective members (P1, P2). Within the optical system, the number of lenses having an Abbe number exceeding 45 may be 2 or more, and may be, for example, the first and third lenses (111, 113). By setting the refractive index and Abbe number of each of these lenses, the influence of chromatic aberration can be controlled.

[0216] The refractive index (Nd1-Nd4) and Abbe number (Vd1-Vd4) of each of the above lenses (111-114) can satisfy at least one of the following conditions.

[0217] Condition 1: Nd1 < Nd2

[0218] Condition 2: 1.5 < Nd1, Nd3 < 1.6

[0219] Condition 3: 1.6 < Nd2, Nd4 < 2.0

[0220] Condition 4: Vd2,Vd4 < Vd1,Vd3

[0221] Depending on the refractive index and Abbe number, the optical system (1000) can have improved chromatic aberration control characteristics.

[0222]

[0223] The focal length (F1, F2, F3, F4) of each lens (111-114) can satisfy the following conditions.

[0224] Condition 1: F1 < |F2|

[0225] Condition 2: |F2| < |F3|

[0226] Condition 3: |F4| < |F3|

[0227] Condition 4: 0.5 < |F2| / |F4|< 1.5

[0228] Among the absolute values ​​of the focal lengths of the lenses, the largest lens is the third lens (113), and can satisfy a range of 50 mm or more, for example, a range of 50 mm to 350 mm or a range of 200 mm to 300 mm.

[0229]

[0230] In Fig. 11, the height of the optical system (1000) is the sum of the first optical axis distance (T1) from the center of the object-side surface (S1) of the first lens (111) to the reflective surface (PR1) of the first reflective member (P1) and the distance from the center of the reflective surface (PR1) of the first reflective member (P1) to the lower end of the first reflective member (P1) or the second reflective member (P2). The height of the optical system (1000) is less than twice the first optical axis distance (T1). The third optical axis distance (T3) from the reflective surface (PR2) of the second reflective member (P2) to the center of the image sensor (190) may be smaller than the first optical axis distance (T1).

[0231] The second optical axis distance (T2) from the reflective surface (PR1) of the first reflective member (P1) to the reflective surface (PR2) of the second reflective member (P2) may affect the length of the optical system (1000) in the first direction (X). The total length (TTL) of the optical system (1000) is the length of the first and second optical axes (OA1, OA2) from the center of the object-side surface (S1) of the first lens (101) to the image sensor (192), which is the sum of the first, second, and third optical axis distances (T1, T2, T3). Since the image sensor (190) is arranged parallel to the first direction (X), the image sensor (190) and the first reflective member (P1) may not overlap in the first direction (X).

[0232] As shown in Fig. 12, the second reflective member (P2) can reflect the incident light toward the opposite side of the object. Accordingly, the optical filter (192) and the image sensor (190) can be spaced further apart than the second reflective member (P2). Since the optical filter (192) and the image sensor (190) are arranged in the opposite side of the object side of the second reflective member (P2), the height of the optical system in the third direction (Z) can increase. As another example, the second reflective member (P2) can have a 43 degree inclination angle of the reflective surface (PR2), in which case the height of the optical system can be reduced.

[0233] As shown in Fig. 19, the fourth lens (114) can be moved in the direction of the optical axis (OA) between the first and second reflective members (P1, P2), and the first to third lenses (111, 112, 113) arranged on the object side of the first reflective member (P1) can be fixed in position. In the direction orthogonal to the optical axis (OA), the effective length of the second reflective member (P2) can be greater than the effective length of the first reflective member (P1). Accordingly, even if at least one or both of the fourth lenses (114) are moved, light loss can be reduced.

[0234]

[0235] (A)(B) of FIG. 15 are graphs showing the diffraction MTF (Modulation transfer function) in the optical system of FIG. 11 and FIG. 12, and are graphs showing the modulation ratio according to the spatial frequency. FIG. 16 is a graph showing the aberration characteristics of the optical system of FIG. 11, and FIG. 17 is a graph showing the aberration characteristics of the optical system of FIG. 12. Referring to FIG. 16 and FIG. 17, these are graphs measuring spherical aberration, astigmatism, and distortion aberration from left to right in the aberration graph of the optical system. The X-axis may represent the focal length (mm) and the distortion degree (%), and the Y-axis may represent the height of the image. Additionally, the graph for spherical aberration is a graph for light in the wavelength bands of about 470 nm, about 555 nm, about 610 nm, and about 650 nm, and the graph for astigmatism and distortion is a graph for light in the wavelength band of 555 nm.

[0236] Fig. 18(A) is a graph showing relative illumination according to the relative sensor height (relative Fielded height) of the optical system of Fig. 11, and Fig. 18(B) is a graph showing relative illumination according to the relative sensor height of the optical system of Fig. 12. As shown in Figs. 18(A) and (B), it can be seen that the relative illumination is highest in the center (0.0) field (Field) of the image sensor, and also appears to be 80% or more at the end (1.0) field. The optical system (1000) according to the second embodiments has improved resolution and can have good optical performance not only in the center of the field of view (FOV) but also in the periphery.

[0237]

[0238] The optical system (1000) according to the embodiment disclosed above can satisfy at least one or two or more of the mathematical equations described below. Accordingly, the optical system (1000) according to the embodiment can have improved optical characteristics. For example, when the optical system (1000) satisfies the mathematical equations, the optical system (1000) can effectively control aberration characteristics such as chromatic aberration and distortion aberration, and can have good optical performance even in the center and periphery of the field of view (FOV). The optical system (1000) can have improved resolution, and can have a slimmer and more compact structure. Hereinafter, the units of values ​​such as thickness, interval, effective length, radius of curvature, and focal length of the first to sixth lenses are mm.

[0239] [Mathematical Formula 1] 2 < nLG1

[0240] In mathematical expression 1, nLG1 is the number of lenses of the first lens group (LG1). Preferably, 2 < nLG1 < 4.

[0241] [Equation 2] 0.5 < CA11 / PSA11 < 1.7

[0242] CA11 is the effective length of the first surface (S1) of the first lens (101, 111), and PSA11 is the length of the incident surface (PS1) of the first reflective member (P1) in the first direction (X). By satisfying mathematical expression 2, light incident through the first lens (101, 111) can be refracted to the entire area of ​​the incident surface (PS1) of the first reflective member (P1). Mathematical expression 2 can satisfy 1 < CA11 / PSA11 < 1.7.

[0243] [Mathematical Formula 3] 5 < TD1 / MG1 < 20

[0244] In mathematical expression 3, TD1 is the optical axis distance of the first lens group (LG1), and MG1 is the optical axis spacing between the first lens group (LG1) and the first reflective member (P1). Mathematical expression 3 can satisfy 10 < TD1 / MG1 < 18.

[0245] [Mathematical Formula 4] 1 < (CT1+CT2) < 3

[0246] In mathematical expression 4, the sum of the central thicknesses (CT1, CT2) of the first and second lenses is set to the above range, thereby improving the aberration characteristics of the optical system.

[0247] [Mathematical Formula 5] 0 < L1R1*L1R2

[0248] L1R1 is the radius of curvature of the object-side surface of the first lens, and L1R2 is the radius of curvature of the sensor-side surface of the first lens. By satisfying mathematical expression 5, the first lens can provide a convex meniscus shape toward the object, and can increase the amount of light incident through the first lens. Preferably, L1R1 < L1R2 can be satisfied.

[0249] [Equation 6] 0 < FLG1

[0250] FLG1 is the focal length of the first lens group and can have positive refractive power. Since it satisfies mathematical expression 6, it can focus the incident light toward the first optical axis (OA1) and increase the amount of light incident on the incident surface (PS1) of the first reflective member (P1).

[0251] [Equation 7] 1 < TD1 / TD2 < 15

[0252] TD1 is the optical axis distance of the first lens group (LG1), and TD2 is the optical axis distance of the second lens group (LG2). That is, since TD2 < TD1 is satisfied, the imaging characteristics of the optical system can be improved and AF operation can be enabled. Preferably, 2 < TD1 / TD2 < 12 can be satisfied.

[0253] [Equation 8] 0 < |FLG1 / FLG2| < 1

[0254] In mathematical expression 8, the absolute value of the focal length of the first lens group may be smaller than the absolute value of the focal length of the second lens group. Preferably, 0.2 < |FLG1 / FLG2| < 0.8 may be satisfied. Since mathematical expression 8 is satisfied, the aberration characteristics of the optical system can be improved.

[0255] [Equation 9] 2 < TTL / TD1 < 10

[0256] In mathematical expression 9, TTL is the optical axis distance in the first and second axis directions from the center of the object-side surface of the first lens through the first and second reflective members to the upper surface of the image sensor (190). Since mathematical expression 9 is satisfied, the optical system does not need to be arranged lengthwise in any one axis direction. Preferably, 3 < TTL / TD1 < 8 can be satisfied.

[0257] [Equation 10] 2 < CT_Max / CT_Min < 6

[0258] CT_Max is the maximum central thickness among the lenses, and CT_Min is the minimum central thickness among the lenses. When mathematical expression 10 is satisfied, the optical system (1000) can be reduced in size, for example, the total track length (TTL) can be reduced. Preferably, 2 < CT_Max / CT_Min < 4 can be satisfied.

[0259]

[0260] [Equation 11] 1< CA11 / CA32 <3

[0261] In mathematical expression 11, since the effective length (CA11) of the object-side surface of the first lens is arranged to be greater than the effective length (CA32) of the sensor-side surface of the third lens, the amount of light incident on the first reflective member (P1) by the first lens (101, 111) can be increased. In addition, since mathematical expression 11 is satisfied, the decrease in the amount of light that proceeds through the first lens arranged on the incident side of the first reflective member (P1) and the third lens arranged on the output side of the first reflective member (P1) can be suppressed. Preferably, 1 < CA11 / CA32 < 2 can be satisfied.

[0262] [Equation 12] 0.5 < CA31 / CAn2 < 1.5

[0263] In mathematical expression 12, CA31 is the radius of curvature of the sensor-side surface of the third lens arranged on the incident surface of the first reflective member (P1), and satisfies the condition: CA31 < 0. Can2 is the radius of curvature of the sensor-side surface of the last lens, i.e., the last lens arranged on the incident surface of the second reflective member (P2), and satisfies the condition: Can2 < 0. That is, by setting the radii of curvature of the lens surfaces adjacent to the incident surfaces of the first and second reflective members (P1, P2), the aberration characteristics of the optical system can be improved. Preferably, 0.6 < CA31 / CAn2 < 1.2 can be satisfied. The first embodiment satisfies 0.5 < CA31 / CA52 < 1.5, and the second embodiment satisfies 0.5 < CA31 / CA42 < 1.5.

[0264] [Equation 13] 1 < CA11 / CAn2 < 3

[0265] Since mathematical expression 13 is satisfied, the deterioration of the chromatic aberration characteristics of the foldable optical system can be prevented. Preferably, 1 < CA11 / CAn2 < 2 can be satisfied. The first embodiment satisfies 1 < CA11 / CA52 < 3, and the second embodiment satisfies 1 < CA11 / CA42 < 3.

[0266] [Mathematical Formula 14] 1 < CA_Max / CA_Min < 3

[0267] CA_Max is the maximum effective length among the lens surfaces of the lenses, and CA_Min is the minimum effective length among the lens surfaces of the lenses. Since it satisfies mathematical expression 13, the aberration characteristics of the optical system can be improved. Preferably, 1 < CA_Max / CA_Min < 2 can be satisfied.

[0268] [Equation 15] 3 < CA1 / CT1 < 9

[0269] Since the effective length (CA1) and the central thickness (CT1) of the first lens are satisfied in mathematical expression 15, the incident light can be controlled and the thickness of the first lens group can be provided slimly. Preferably, 3 < CA1 / CT1 < 7 can be satisfied.

[0270] [Equation 16] 5 < CA2 / CT2 < 15

[0271] Since the effective length (CA2) and the central thickness (CT2) of the second lens are satisfied in mathematical expression 16, the incident light can be controlled and the thickness of the first lens group can be provided slimly. Preferably, 6 < CA2 / CT2 < 11 can be satisfied.

[0272] [Mathematical Formula 17] 1 < CA3 / CT3 < 9

[0273] Since the effective length (CA3) and the central thickness (CT3) of the third lens in mathematical expression 17 are satisfied, light passing through the first lens group (LG1) can be controlled and the thickness and height of the first lens group can be provided slimly. Preferably, the first embodiment satisfies 5 < CA3 / CT3 < 9, and the second embodiment satisfies 1 < CA3 / CT3 < 4.

[0274] [Equation 18] 4 < CAn / CTn < 10

[0275] Since the effective length (CAn) and the central thickness (CTn) of the last lens in mathematical expression 18 are satisfied, the path of the light emitted through the last lens can be controlled and a slim optical system can be provided. Preferably, the first embodiment satisfies 4 < CA5 / CT5 < 10, and the second embodiment satisfies 4 < CA4 / CT4 < 10.

[0276] [Equation 19] 30 < |Vd1 - Vd2| < 60

[0277] In mathematical expression 19, by setting the Abbe numbers (Vd1, Vd2) of the first and second lenses, the color dispersion of light transmitted through the first and second lenses can be controlled. Preferably, 30 < |Vd1 - Vd2| < 55 can be satisfied.

[0278] [Equation 20] 15 < |Vd1 - Vdn| < 60

[0279] In mathematical expression 20, the Abbe numbers (Vd1, Vdn) of the first and last lenses can be set to control the chromatic dispersion of light transmitted through the first and last lenses. Preferably, 30 < |Vd1 - Vd6| < 55 can be satisfied.

[0280] [Mathematical Formula 21] 1.5 < Nd1 < Nd2

[0281] In mathematical expression 21, by setting the refractive indices (Nd1, Nd2) at the d-line of the first and second lenses, the color dispersion of light transmitted through the first and second lenses can be controlled. Preferably, 1.6 < Nd2 < 2.0 can be satisfied.

[0282]

[0283] [Equation 22] 0 < L1R1 / L2R2 < 1

[0284] In mathematical expression 22, the radius of curvature (L1R1) of the object-side surface of the first lens and the radius of curvature (L1R2) of the sensor-side surface of the second lens can be set. Since mathematical expression 22 is satisfied, the optical system can control the refractive power of the first and second lenses and provide good optical performance.

[0285] [Equation 23] 0 < L1R1 / |L3R1| < 1

[0286] In mathematical expression 23, the radius of curvature (L1R1) of the object-side surface of the first lens and the radius of curvature (L3R1) of the object-side surface of the third lens can be set. Since mathematical expression 23 is satisfied, the optical system can control the refractive power of the first and third lenses and provide good optical performance. The first and second embodiments satisfy L3R1 < 0.

[0287] [Equation 24] 0 < |L3R2| / |L4R1| < 1

[0288] In mathematical expression 24, the radius of curvature (L3R2) of the sensor-side surface of the third lens and the radius of curvature (L4R1) of the object-side surface of the fourth lens can be set. Since mathematical expression 24 is satisfied, the optical system can control the refractive power of the third and fourth lenses arranged on the incident and exit sides of the first reflective member (P1) and provide good optical performance. The first and second embodiments satisfy L3R2 < 0 and L4R1 < 0.

[0289] [Equation 25] 0 < LnR2

[0290] In mathematical expression 25, the radius of curvature (LnR2) of the sensor-side surface of the last lens can be set to a positive value. Since mathematical expression 25 is satisfied, the optical system can control the refractive power of the last lens placed on the incident side of the second reflective member (P2) and provide good optical performance.

[0291]

[0292] [Equation 26] 1 < TTL / T2 < 3

[0293] T2 is the second optical axis distance from the reflective surface of the first reflective member (P1) to the reflective surface of the second reflective member (P2) along the second optical axis (OA2). Since it satisfies mathematical expression 26, the length of the first direction (X) of the optical system can be reduced. Preferably, 2 < TTL / T2 < 3 can be satisfied.

[0294] [Mathematical Formula 27] 1 < TTL / F1 < 3

[0295] In mathematical expression 27, the total length of the optical system in the first and second directions and the focal length of the first lens (101, 111) can be set. Since mathematical expression 27 is satisfied, the refractive power of the first lens can be controlled and the TTL can be reduced. Preferably, 1.5 < TTL / F1 < 2.5 can be satisfied.

[0296] [Equation 28] 0 < |F / F3| < 2

[0297] In mathematical expression 28, the overall focal length (F) of the optical system and the focal length of the third lens (103, 113) can be set. Since mathematical expression 28 is satisfied, the optical system can improve the resolution by controlling the refractive power of the incident light, and can improve the aberration characteristics such as chromatic aberration and distortion aberration of the optical system. Preferably, 0.5 < |F / F3| < 1 can be satisfied.

[0298] [Equation 29] 0 < |Fn / F3| < 1

[0299] In mathematical expression 29, the focal length (F1) of the third lens (103, 113) of the optical system and the focal length (Fn) of the last lens (105, 114) can be set. Since mathematical expression 29 is satisfied, the refractive power of the incident-side lens of each reflective member (P1, P2) of the optical system can be controlled, thereby improving the resolution. Preferably, 0 < |Fn / F3| < 0.5 can be satisfied.

[0300] [Equation 30] 1 < TTL / F < 2

[0301] In mathematical expression 30, the total length of the optical system in the first and second directions and the total focal length can be set. Since mathematical expression 30 is satisfied, the length of the optical system can be adjusted. Preferably, 1 < TTL / F < 1.5 can be satisfied.

[0302]

[0303] [Mathematical Formula 31] 1 < F1 / L1R1 < 5

[0304] In mathematical expression 31, the focal length of the first lens (101, 111) and the radius of curvature (L1R1) of the object-side surface (S1) of the first lens can be set. Accordingly, the optical system can improve the aberration characteristics of the first lens (101, 111) and adjust the optical axis distance of the first lens group. Preferably, 1.2 < F1 / L1R1 < 3 can be satisfied.

[0305] [Equation 32] 1 < |F2 / L2R2| < 5

[0306] In mathematical expression 32, the focal length of the second lens (102, 112) and the radius of curvature (L2R2) of the sensor-side surface (S4) of the second lens can be set. Accordingly, the optical system can improve the aberration characteristics of the second lens (102, 112) and adjust the optical axis distance of the first lens group. Preferably, 2 < |F2 / L2R2| < 4.5 can be satisfied.

[0307] [Equation 33] LnR1 < 0

[0308] In mathematical expression 33, the radius of curvature (LnR1) of the object-side surface of the last lens (105, 114) can be set to a negative value. Since mathematical expression 33 is satisfied, the last lens can refract the incident light toward the second reflective member.

[0309]

[0310] [Mathematical Formula 34] 2 mm < GP1P2 < 5 mm

[0311] GP1P2 is the optical axis distance between the reflective surface (PR1) of the first reflective member (P1) and the reflective surface (PR2) of the second reflective member (P2), and can adjust the length of the optical system. Accordingly, the length of the optical system in the direction of the second optical axis (OA2) can be reduced. Preferably, 2.2 mm < GP1P2 < 4 mm can be satisfied.

[0312] [Mathematical Formula 35] 10 degrees < FOV < 50 degrees

[0313] FOV (Field of view) refers to the angle of view of the optical system (1000), and can provide an optical system of less than 50 degrees. The FOV can be 15 degrees or more, for example, in the range of 13 degrees to 25 degrees.

[0314] [Equation 36] 2 < F / EPD < 5

[0315] In mathematical expression 36, the entrance pupil diameter (EPD) and the overall focal length (F) of the optical system (1000) can be set. When mathematical expression 36 is satisfied, the optical system (1000) can control the overall brightness and have good optical performance in the center and periphery of the field of view (FOV). Preferably, mathematical expression 36 can satisfy 2.2 < F / EPD < 3.5.

[0316] [Equation 37] 5 < TTL / ImgH < 10

[0317] In mathematical expression 37, the total optical axis length (TTL) of the optical system and the diagonal length (ImgH) from the optical axis of the image sensor (190) can be set. If mathematical expression 60 is satisfied, high-quality implementation and a slim structure can be achieved. Preferably, mathematical expression 37 can satisfy 5 < TTL / ImgH < 9.

[0318] [Equation 38] 1 < BFL / ImgH < 5

[0319] Mathematical expression 38 can set the optical axis distance between the image sensor (190) and the last lens and the diagonal length from the optical axis of the image sensor (190). When Mathematical expression 38 is satisfied, the optical system (1000) can secure a back focal length (BFL) and minimize the distance between the last lens and the image sensor (190), thereby having good optical characteristics in the center and periphery of the field of view (FOV). Preferably, Mathematical expression 38 can satisfy 2 < BFL / ImgH < 4.

[0320] [Mathematical Formula 39] 2mm < ImgH

[0321] In mathematical expression 39, by setting the diagonal length (2*ImgH) of the image sensor (190) to exceed 4 mm, an optical system having high resolution can be provided. Mathematical expression 39 can preferably satisfy 2 mm < ImgH < 6 mm or 3 mm < ImgH < 5 mm.

[0322] [Mathematical Formula 40] 5mm < F < 40mm

[0323] In mathematical expression 40, the overall focal length (F) can be set to suit the optical system, and preferably, 10 mm < F < 30 mm can be satisfied.

[0324] [Mathematical Formula 41] 10mm < TTL < 40mm

[0325] In mathematical expression 41, TTL (Total track length) means the distance from the center of the first surface (S1) of the first lens to the upper surface of the image sensor (190) on the optical axis (OA). Preferably, mathematical expression 41 can satisfy 15 mm < TTL < 35 mm.

[0326] [Mathematical Formula 42] 4mm < BFL < 10mm

[0327] Mathematical expression 42 can set the back focal length (BFL) of the foldable optical system. That is, the BFL can secure the installation space for the second reflective member and the optical filter (192), improve the assemblability of components through the gap between the image sensor (190) and the final lens, and enhance the joint reliability. Mathematical expression 42 can preferably satisfy 6 mm < BFL < 10 mm.

[0328] [Equation 43] 0 < |Max_Distortion| < 3

[0329] In mathematical expression 43, distortion refers to the maximum value or the maximum value of distortion from the center (0.0F) of the image sensor to the diagonal end (1.0F) based on the optical characteristics detected by the image sensor (190). When the optical system (1000) satisfies mathematical expression 43, the optical system (1000) can improve the distortion characteristics and set conditions for image processing. Preferably, 0 < |Max_Distortion| < 1.5 can be satisfied.

[0330] Table 1 shows the distortion characteristics from the center (Dist F1) to the end (Dist F11) of the first to third embodiments.

[0331] Sensor height Example 1 Example 2 Dist(F1) 0 0 Dist(F2) 0.007 3 0.0164 Dist(F3) 0.029 0.0632 Dist(F4) 0.064 5 0.1336 Dist(F5) 0.114 3 0.2262 Dist(F6) 0.178 3 0.3391 Dist(F7) 0.256 8 0.4722 Dist(F8) 0.350 2 0.6277 Dist(F9) 0.458 7 0.8098 Dist(F10) 0.58 2 9 1.0232 Dist(F11) 0.72 3 1.2722

[0332]

[0333] [Equation 44]

[0334]

[0335] In mathematical expression 44, Z may represent Sag, which is the distance from any position on the aspherical surface to the vertex of the aspherical surface in the direction of the optical axis. Y may represent the distance from any position on the aspherical surface to the optical axis in the direction perpendicular to the optical axis. c may represent the curvature of the lens, and K may represent the conic constant. In addition, A, B, C, D, E, F, etc. may represent aspheric coefficients.

[0336]

[0337] An optical system (1000) according to an embodiment can satisfy at least one or more mathematical expressions from mathematical expressions 1 to 43, have improved resolution, and improve aberration and distortion characteristics. The optical system (1000) can secure a BFL for a foldable optical system, and have good optical performance in the center and periphery of the field of view (FOV). In addition, when the optical system (1000) satisfies at least one mathematical expression from mathematical expressions 1 to 43, a slimmer and more compact optical system and a camera module having the same can be provided.

[0338] Table 2 shows the items of the mathematical formulas described above in the optical system (1000) according to the embodiments, and shows the TTL, BFL, F value which is the total effective focal length, ImgH, the focal length (F1, F2, F3, F4, F5, F6) of each of the first to sixth lenses, the edge thickness (mm), and the refractive power (FLG1, FLG2, FLG3) of each lens group of the optical system (1000).

[0339] Item Example 1 Example 2 F17.530 16.277 F110.1059.0988 F2-18.044-24.637 F348.483-224.76 F48.686-27.052 F5-6.240 FLG114.059 13.969 FLG2-24.260-24.561 ET10.547 0.447ET20.6650.527ET30.4461.569ET40.3080.609ET50.954FOV16.41117.51 9EPD5.1645.4BFL8.0938.236ImgH2.5492.552TTL19.00019.137F#3.3953.014

[0340]

[0341] Table 3 shows the result values ​​for the mathematical expressions 1 to 43 described above in the optical system (1000) according to the embodiment. Referring to Table 3, it can be seen that the optical system (1000) satisfies at least one, two or more, or three or more of the mathematical expressions 1 to 43. Accordingly, the optical system (1000) can improve optical performance and optical characteristics in the center and periphery of the field of view (FOV).

[0342] Mathematical Formula Example 1 Example 2 12 < nLG1 3 3 2 0.5 < CA11 / PSA11 < 1.7 1.5 2 2 1.44835 < TD1 / MG1 < 2 012.26 4 15.66841 < (CT1+CT2) < 31.906 1.67450 < L1R1*L1R2 6 2.59 7 9 3 3.79660 < FLG1 1 4.05 9 13.96971 < TD1 / TD2 < 152.609.4080 < |FLG1 / FLG2| < 10.5800.56992 < TTL / TD1 < 105.1644.071102 < CT_Max / CT_Min < 62.8123.000111< CA11 / CA32 <31.5281.459120.5 < CA41 / CAn2 < 1.51.0010.996131 < CA11 / CAn2 < 31.4621.128141 < CA_Max / CA_Min < 31.5281.459153 < CA1 / CT1 < 94.0054.516165 < CA2 / CT2 < 158.9248.369171 < CA3 / CT3 < 97.8782.527184 < CAn / CTn < 108.0338.0701930 < |Vd1 - Vd2| <6043.38149.3942015 < |Vd1 - Vdn| < 6045.72949.394211.5 < Nd1 < Nd2SatisfiedSatisfied220 < L1R1 / L2R2 < 10.3070.030230 < L1R1 / |L3R1| < 10.2360.746240 < |L3R2| / |L4R1| < 10.6120.035250 < LnR237.27019.917261 < TTL / T2 < 32.1942.648271< TTL / F1 < 31.8802.103280 < |F / F3| < 20.9720.661290 < |Fn / F3| < 10.1290.120301 < TTL / F < 21.0841.176311 < F1 / L1R1 < 52.3051.729321 < |F2 / L2R2| < 52.4883.89533LnR1 < 0-4.497-232.560342 < GP1P2 < 53.6112.5263510 < FOV < 5016.41117.519361 < F / EPD < 53.3953.014375 < TTL / ImgH < 107.4547.498381 <BFL / ImgH < 53.1753.227392 < ImgH2.552.55405 < F < 4017.53016.2774110 < TTL < 4019.00019.137424 < BFL < 108.0938.236430 < |Max_Distortion| < 30.7231.272.

[0343]

[0344] Fig. 20 is a drawing showing an example of a mobile terminal to which a camera module according to an embodiment is applied.

[0345] Referring to FIG. 20, the mobile terminal (1) may include a camera module (10) provided on the rear. 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 function, a zoom function, and an OIS function.

[0346] The above camera module (10) can process still images or video frames obtained by the image sensor (190) in shooting mode or video call mode. The processed image frames can be displayed on the 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 of the mobile terminal (1).

[0347] 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 have improved distortion and aberration characteristics. In addition, the camera module (10) may have good optical performance at the center and periphery of the field of view (FOV).

[0348] In addition, 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) disclosed above 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.

[0349] In addition, the mobile terminal (1) may further include a flash module (33). The flash module (33) may include a light-emitting element that emits light internally. The flash module (33) may be operated by the camera operation of the mobile terminal or by the user's control.

[0350]

[0351] Fig. 21 is an example of a plan view of a vehicle to which a camera module or optical system according to an embodiment of the invention is applied. Referring to Fig. 21, a vehicle camera system according to an embodiment of the invention includes an image generating unit (11), a first information generating unit (12), a second information generating unit (21, 22, 23, 24), and a control unit (14). The image generating unit (11) may include at least one camera module (20) disposed in the vehicle, and may capture images of the front of the vehicle and / or the driver to generate a front image or an interior image of the vehicle. The image generating unit (11) may capture images of the surroundings of the vehicle in one or more directions as well as the front of the vehicle using the camera module (20), to generate an image of the surroundings of the vehicle. Here, the front image and the surrounding images may be digital images, and may include color images, black and white images, infrared images, etc. In addition, the front image and the surrounding images may include still images and moving images. The image generation unit (11) provides the driver image, the front image, and the surrounding image to the control unit (14). Next, the first information generation unit (12) may include at least one radar and / or camera placed in the vehicle, and detects the front of the vehicle to generate first detection information. Specifically, the first information generation unit (12) is placed in the vehicle, and detects the position and speed of vehicles located in front of the vehicle, the presence and position of pedestrians, etc. to generate the first detection information.

[0352] By using the first detection information generated by the first information generating unit (12), the distance between the own vehicle and the vehicle in front can be controlled to be maintained at a constant level, and the stability of vehicle operation can be improved in specific preset cases, such as when the driver wants to change the driving lane of the own vehicle or when backing up and parking. The first information generating unit (12) provides the first detection information to the control unit (14). The second information generating unit (21, 22, 23, 24) detects each side of the own vehicle and generates second detection information based on the front image generated by the image generating unit (11) and the first detection information generated by the first information generating unit (12). Specifically, the second information generating unit (21, 22, 23, 24) may include at least one radar and / or camera disposed in the own vehicle, and may detect the position and speed of vehicles located on the side of the own vehicle or capture images. Here, the second information generation units (21, 22, 23, 24) can be placed at the front two corners, side mirrors, and rear center and rear two corners of the vehicle, respectively.

[0353] At least one information generating unit of these vehicle camera systems may include the optical system and the camera module having the same as described in the above-described embodiments, and may provide or process information acquired through the front, rear, each side, or corner area of ​​the vehicle to a user to enable autonomous driving or to protect the vehicle and objects from surrounding safety. The optical system of the camera module according to the embodiment of the invention may be installed in multiple units in a vehicle to enhance safety regulations, autonomous driving functions, and convenience. In addition, the optical system of the camera module is applied in a vehicle as a component for control such as a lane keeping assistance system (LKAS), a lane departure warning system (LDWS), and a driver monitoring system (DMS). These vehicle camera modules can implement stable optical performance even with changes in ambient temperature and provide modules with competitive prices, thereby ensuring the reliability of vehicle components.

[0354]

[0355] 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. exemplified in each embodiment can be combined or modified in other embodiments by those skilled in the art to which the embodiments pertain. Therefore, the contents related to such combinations and modifications should be construed as falling within the scope of the present invention.

[0356] In addition, although the above description focuses on examples, these are merely examples and do not limit the present invention. Those skilled in the art to which the present invention pertains will appreciate that various modifications and applications not exemplified above are possible without departing from the essential characteristics of the present invention. For example, each component specifically shown in the examples can be modified and implemented. In addition, differences related to such modifications and applications should be interpreted as being included within the scope of the present invention defined in the appended claims.

Claims

1. First reflective member; A second reflective member spaced apart from the first reflective member; A first lens group arranged between the first reflective member and the object; and A second lens group is included, which is arranged between the first reflective member and the second reflective member. The number of lenses in the first lens group is greater than the number of lenses in the second lens group, The above first lens group has positive power, The above second lens group has negative power, An optical system in which the first lens closest to the object among the lenses of the first lens group has positive power.

2. In paragraph 1, The first lens group includes second and third lenses sequentially aligned along the first optical axis from the first lens toward the first reflective member, The second lens group includes fourth and fifth lenses sequentially aligned along a second optical axis orthogonal to the first optical axis between the first and second reflective members, The optical system wherein the fifth lens has negative power.

3. In paragraph 1, The first lens group includes second and third lenses sequentially aligned along the first optical axis from the first lens toward the first reflective member, The second lens group includes a fourth lens sequentially aligned along a second optical axis orthogonal to the first optical axis between the first and second reflective members, The above fourth lens is an optical system having negative power.

4. In paragraph 1, An optical system wherein the last lens closest to the second reflective member has negative power.

5. In any one of paragraphs 1 to 4, An optical system in which the effective diameter of the first lens is the largest among the lenses of the first and second lens groups.

6. In any one of paragraphs 1 to 4, An optical system in which at least two of the lenses of the first and second lens groups have a refractive index exceeding 1.

6.

7. In any one of paragraphs 1 to 4, An optical system in which the lenses adjacent to the first lens and the second lens have a convex meniscus shape toward the object.

8. In any one of paragraphs 1 to 4, The second lens group is moved between the first and second reflective members, An optical system in which the object-side surface of the last lens adjacent to the second reflective member has a concave shape.

9. In any one of paragraphs 1 to 4, The optical axis distance of the first lens group is more than 1 time the optical axis distance of the second lens group, An optical system in which the object-side surface of the last lens adjacent to the second reflective member has a concave shape.

10. In any one of paragraphs 1 to 4, It includes an image sensor arranged on the emission side of the second reflective member, An optical system in which the image sensor is positioned closer to the object than the position of the second reflective member.

11. In any one of paragraphs 1 to 4, It includes an image sensor arranged on the emission side of the second reflective member, An optical system in which the image sensor is positioned in the opposite direction of the object with respect to the second reflective member.

12. In any one of paragraphs 1 to 4, The above first reflective member is a prism, The above second reflective member is a prism, An optical system in which the effective length of the second reflective member is greater than the effective length of the first reflective member.

13. In any one of paragraphs 1 to 4, The above first lens is an optical system made of glass.

Images