Optical Department

Abstract

An optical system according to an embodiment of the present invention includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, and a ninth lens arranged sequentially along an optical axis from an object side to a sensor side, wherein the first lens has a convex object-side surface, the second lens has a convex object-side surface, the third lens has positive refractive power and a convex object-side surface, the fourth lens has negative refractive power and a concave sensor-side surface, the eighth lens has positive refractive power, and at least one of the object-side surface and the sensor-side surface has at least one inflection point, and the ninth lens has negative (-) refractive power, and the object-side surface and the sensor-side surface have at least one inflection point.

Description

Technical Field

[0001] Embodiments of the present invention relate to an optical system for high resolution.

Background Art

[0002] A camera module performs a function of photographing an object and storing it as an image or video, and is mounted on various applications. In particular, the camera module is manufactured in a ultra-small size and is applied not only to portable devices such as smartphones, tablet PCs, and notebook computers, but also to drones, vehicles, etc., providing various functions. For example, the optical system of the camera module may include an imaging lens for forming an image and an image sensor for converting the formed image into an electrical signal. At this time, the camera module can perform an autofocus (AF) function of automatically adjusting the distance between the image sensor and the imaging lens to align the focal length of the lens, and can perform a zooming function of zooming in (zoom up) or zooming out (zoom out) by increasing or decreasing the magnification of a distant object through a zoom lens. In addition, the camera module employs an image stabilization (IS) technology to correct or prevent image blur caused by the movement of the camera due to an unstable fixing device or the movement of the user. The most important element for such a camera module to obtain an image is the imaging lens for forming the image. Recently, there has been an increasing interest in high resolution, and research using five or six lenses has been underway to implement this. In addition, research using a plurality of imaging lenses having a positive (+) refractive power or a negative (-) refractive power has been underway for the implementation of high resolution. However, when arranging a plurality of lenses, there is a problem that it is difficult to derive excellent optical characteristics and aberration characteristics. Therefore, a new optical system capable of solving the above-described problems is required.

Summary of the Invention

[0003] The embodiments of the present invention aim to provide an optical system with improved optical properties. The embodiments of the present invention aim to provide an optical system having at least nine lenses. The embodiments of the present invention aim to provide an optical system in which at least two lenses having positive (+) refractive power and at least two lenses having negative (-) refractive power are aligned with respect to the optical axis among the at least nine lenses. [Means for solving the problem]

[0004] An optical system according to an embodiment of the present invention includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, and a ninth lens, which are sequentially arranged along the optical axis from the object side to the sensor side, wherein the first lens has a convex object side, the second lens has a positive refractive power and a convex object side, the third lens has a negative refractive power and a concave sensor side, the eighth lens has a positive refractive power and at least one of its object side and sensor side has at least one inflection point, and the ninth lens has a negative refractive power and can have at least one inflection point on both its object side and sensor side.

[0005] According to embodiments of the present invention, the central thickness of the second lens may be thicker than the central thicknesses of the first, third to ninth lenses. The refractive indices of the first, second, fifth, seventh, and ninth lenses may be smaller than those of the third, sixth, and eighth lenses. The Abbe numbers of the first, second, fifth, seventh, and ninth lenses are 50 or greater, and the Abbe numbers of the third and sixth lenses may be less than 30. At least one of the first, fourth, fifth, sixth, and seventh lenses may have a positive or negative refractive power.

[0006] The optical system according to an embodiment of the present invention includes an image sensor on the sensor side of the ninth lens and an optical filter between the image sensor and the ninth lens. The optical system satisfies Formula 1 and Formula 2: [Equation 1] 0 < BFL / TTL < 0.3 and [Equation 2] 0 < BFL / Img < 0.3. Here, BFL is the distance from the vertex or center on the sensor side of the ninth lens to the image sensor, TTL is the distance from the vertex or center of the first surface on the object side of the first lens to the image sensor, and Img can be the vertical distance from the optical axis in the image sensor to 1.0F at the diagonal end.

[0007] According to an embodiment of the present invention, an image sensor is included on the sensor side of the ninth lens and an optical filter is included between the image sensor and the ninth lens. The optical system satisfies Formulas 3, 4, and 5: [Equation 3] 0.5 < F / TTL < 1.2, [Equation 4] 0.5 < TTL / (Img×2) < 0.8, and [Equation 5] 0.5 < TTL / (D92×2) < 1.2. Here, TTL is the distance from the center of the first surface on the object side of the first lens to the image sensor, F is the total effective focal length of the optical system, Img is the vertical distance from the optical axis in the image sensor to 1.0F at the diagonal end, and D92 can be the distance from the center of the sensor side surface of the ninth lens on the optical axis to the end of the effective area.

[0008] According to an embodiment of the present invention, when the radius of curvature of the object side surface of the second lens is L2R1 and the absolute value of the radius of curvature of the sensor side surface of the second lens is defined as |L2R2|, 0 < L2R1 / |L2R2| < 0.5 can be satisfied.

[0009] According to an embodiment of the present invention, when the absolute value of the radius of curvature of the object side surface of the third lens is |L_{3}R1| and the radius of curvature of the sensor side surface of the third lens is L_{3}R2, the relationship 0.2 < L_{3}R2 / |L_{3}R1| < 1 can be satisfied.

[0010] According to an embodiment of the present invention, when the refractive index of the second lens at 587 nm is G2 and the refractive index of the third lens at 587 nm is G3, the relationship of 0.7 < G2 / G3 < 1.2 can be satisfied.

[0011] According to an embodiment of the present invention, when the central thickness of the first lens is T1, the central thickness of the second lens is T2, and the central thickness of the third lens is T3, the relationships of 0.2 < T3 / T2 < 1 and 0.2 < T1 / T2 < 1 can be satisfied.

[0012] The optical system according to an embodiment of the present invention includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, and a ninth lens sequentially arranged along the optical axis in the direction from the object side to the sensor side. The first lens has a positive or negative refractive power, the object side surface is convex, and the sensor side surface is concave. The second lens has a positive refractive power, the object side surface is convex, and the sensor side surface is convex. The third lens has a negative refractive power, and the sensor side surface is concave. The eighth lens has a positive refractive power, and at least one of the object side surface and the sensor side surface has at least one inflection point. The ninth lens has a negative refractive power, and at least one of the object side surface and the sensor side surface has at least one inflection point. The central thickness of the second lens is thicker than the central thicknesses of each of the first, third to ninth lenses. The edge of the object side surface of the eighth lens protrudes toward the first lens from the center on the optical axis of the object side surface of the eighth lens. The straight line connecting the edge of the object side surface of the eighth lens may be the same as or closer to the first lens than the straight line orthogonal to the optical axis at the center of the object side surface of the seventh lens.

[0013] According to an embodiment of the present invention, the straight line connecting the edge of the object side surface of the eighth lens may be closer to the first lens than the straight line orthogonal to the optical axis at the center of the object side surface of the seventh lens.

[0014] According to embodiments of the present invention, the distance between the third lens and the fourth lens along the optical axis may be greater than the first distance between the first lens and the second lens, and the second distance between the eighth lens and the ninth lens along the optical axis may be greater than the first distance. The first and second distances may be 0.4 mm or more. The center thickness of the second lens may be in the range of 2 to 4 times the center thickness of the third lens. [Effects of the Invention]

[0015] The optical system according to this embodiment can correct aberration characteristics and realize a slim optical system. This allows for miniaturization of the optical system and realizes high image quality and high resolution. Furthermore, the optical system according to this embodiment can block unwanted light from entering the optical system. This reduces aberrations and improves the performance of the optical system. [Brief explanation of the drawing]

[0016] [Figure 1] This is a diagram showing the configuration of the optical system according to the first embodiment of the present invention. [Figure 2] This is a diagram showing the configuration of the optical system according to a second embodiment of the present invention. [Figure 3] This is a diagram showing the configuration of the optical system according to the third embodiment of the present invention. [Figure 4] This is an explanatory diagram showing the relationship between the edge side of the eighth lens and the seventh lens in the first to third embodiments of the present invention. [Figure 5] This is an example in which a reflective member is arranged on the incident side of the optical system of the first to third embodiments of the present invention. [Figure 6] Figures 6(A), (B), and (C) are graphs showing the spherical aberration (longitudinal spherical aberration), astigmatic field curves, and distortion in the optical system shown in Figure 1. [Figure 7] This figure shows the distortion grid in the optical system shown in Figure 1. [Figure 8] Figure 8 is an analysis graph showing the lateral aberration in the region where the relative field height on the optical axis in the tangential field curvature and sagittal field curvature of the optical system of Figure 1 is 0.0 to 1.0. [Figure 9] (A), (B), and (C) of Figure 9 are graphs showing the longitudinal spherical aberration, astigmatic field curves, and distortion in the optical system of Figure 2. [Figure 10] A diagram showing the distortion grid in the optical system of Figure 2. [Figure 11] Figure 11 is an analysis graph showing the lateral aberration in the region where the relative field height on the optical axis in the tangential field curvature and sagittal field curvature of the optical system of Figure 2 is 0.0 to 1.0. [Figure 12] (A), (B), and (C) of Figure 12 are graphs showing the longitudinal spherical aberration, astigmatic field curves, and distortion in the optical system of Figure 3. [Figure 13] A diagram showing the distortion grid in the optical system of Figure 3. [Figure 14] Figure 14 is an analysis graph showing the lateral aberration in the region where the relative field height on the optical axis in the tangential field curvature and sagittal field curvature of the optical system of Figure 3 is 0.0 to 1.0. [Figure 15] A perspective view of a mobile terminal having an optical system according to an embodiment of the present invention. Modes for carrying out the invention

[0017] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. However, the technical idea of the present invention is not limited to some of the described embodiments and can be embodied in various different forms. Within the scope of the technical idea of the present invention, one or more of its components can be selectively combined or replaced between the embodiments. Also, the terms (including technical and scientific terms) used in the embodiments of the present invention can be interpreted as having a meaning generally understood by those with ordinary knowledge in the technical field to which the present invention belongs, unless specifically defined and described. Terms that are commonly used like those defined in a dictionary can be interpreted considering their meaning in the context of the related technology. Also, the terms used in the embodiments of the present invention are for explaining the embodiments and are not intended to limit the present invention. In this specification, the singular form can include the plural form unless otherwise stated in the text. When described as "at least one (or one or more) of A, B, and C", it can include one or more of all the combinations that can be combined with A, B, and C. Also, when explaining the components of the embodiments of the present invention, terms such as first, second, A, B, (a), (b), etc. can be used. Such terms are only for distinguishing the component from other components and do not limit the essence, order, or sequence of the corresponding component. And when a component is described as "connected", "coupled", or "joined" to another component, that component can be directly connected, coupled, or joined to the other component, but also includes the case where it is "connected", "coupled", or "joined" by another component or components existing between that component and the other component. Also, when described as formed or arranged "above or below" each component, above or below includes not only the case where two components are in direct contact with each other, but also the case where one or more other components are formed or arranged between the two components. Also, when expressed as "above or below", it can include not only the meaning of the upper direction but also the lower direction with respect to one component as a reference.

[0018] In this description, the first lens refers to the lens closest to the object, and the last lens refers to the lens closest to the image side (or sensor surface). In this description, unless otherwise specified, the units for lens radius, effective diameter, thickness, distance, BFL (Back Focal Length), TTL (Total track length or Total Top Length), etc., are all in mm. In this specification, the shape of a lens is shown with respect to the optical axis of the lens. For example, when it is said that the object side of a lens is convex, it means that the area near the optical axis on the object side of the lens is convex, not that the area around the optical axis is convex. Therefore, even when it is said that the object side of a lens is convex, the area around the optical axis on the object side of the lens may be concave. In this specification, it is made clear that the thickness and radius of curvature of a lens are measured with respect to the optical axis of the lens. Furthermore, "object side" can refer to the surface of the lens facing the object side with respect to the optical axis, and "image side" can refer to the surface of the lens facing the imaging surface with respect to the optical axis.

[0019] The optical system according to embodiments of the present invention may include multiple lenses. More specifically, the optical system according to the first to third embodiments may include at least nine lenses. As resolution increases, the size of the image sensor also increases, and the number of lenses gradually increases with the resolution of the image sensor. Embodiments of the present invention aim to provide a high-resolution optical system using at least eight lenses.

[0020] Referring to Figures 1 to 3, the optical systems of the first to third embodiments may include, for example, a first lens 111, a second lens 112, a third lens 113, a fourth lens 114, a fifth lens 115, a sixth lens 116, a seventh lens 117, an eighth lens 118, and a ninth lens 119 arranged sequentially from the object side to the image side. The optical system may include an optical filter 192 and an image sensor 190. An optical system having the plurality of lenses 111 to 119 can be defined as a lens optical system, and an optical system further including the lenses 111 to 119, an optical filter 192, and an image sensor 190 can be defined as a camera module. The camera module may include a circuit board and at least one lens holder supporting at least one lens or two or more lenses, and one or more drive members may be provided to move the lens holder in the direction of the optical axis and / or perpendicular to the optical axis.

[0021] The first to ninth lenses 111, 112, 113, 114, 115, 116, 117, 118, and 119 can be arranged sequentially along the optical axis Lx of the optical system. Light corresponding to the image information of an object enters through the first lens 111, second lens 112, third lens 113, fourth lens 114, fifth lens 115, sixth lens 116, seventh lens 117, eighth lens 118, and ninth lens 119, passes through the optical filter 192, is focused on the image sensor 190, and can be acquired as an electrical signal.

[0022] Each of the first to ninth lenses 111, 112, 113, 114, 115, 116, 117, 118, and 119 may include an effective region and an ineffective region. The effective region may be the region through which light incident on each lens passes. That is, the effective region may be the region where incident light is refracted and exhibits optical properties. The ineffective region may be arranged around the effective region. The ineffective region may be a region through which light does not enter. That is, the ineffective region may be a region unrelated to the optical properties of the optical system. Furthermore, the ineffective region may be a region fixed to a barrel (not shown) that houses the lens, or a region where light is blocked by a light-shielding portion or spacer.

[0023] At least one or more of the first to ninth lenses 111, 112, 113, 114, 115, 116, 117, 118, 119, or at least one or more of the fifth to ninth lenses 115, 116, 117, 118, 119, may have a length in a first direction perpendicular to the optical axis Lx that is smaller than the effective diameter in a second direction. Such lenses may be provided in a non-circular shape having a diameter in the second direction and a distance in the first direction that is smaller than the diameter.

[0024] The optical systems shown in Figures 1 to 3 may include an aperture ST for adjusting the amount of incident light. The aperture ST may be positioned between two lenses selected from the first to ninth lenses 111, 112, 113, 114, 115, 116, 117, 118, 119. For example, the aperture ST may be positioned around the outside of the space between the first lens 111 and the second lens 112, or around the outside of the space between the second lens 112 and the third lens 113. The aperture ST may be positioned even closer to the sensor side (or exit surface) of the first lens 111 than to the fourth lens 114.

[0025] As another example, at least one of the first to ninth lenses 111, 112, 113, 114, 115, 116, 117, 118, 119 can function as an aperture. For example, one surface selected from the lens surfaces of the first to ninth lenses 111, 112, 113, 114, 115, 116, 117, 118, 119 can function as an aperture to adjust the amount of light. For example, the area around the sensor side of the first lens 111 or the area around the object side of the second lens 112 can function as an aperture.

[0026] Referring to Figures 1 to 3, the first lens 111 in the optical system can have a positive (+) or negative (-) refractive power. The first lens 111 may be made of a plastic material. The first lens 111 may include a first surface S1 defined as an object side and a second surface S2 defined as a sensor side. The first surface S1 may be convex, and the second surface S2 may be concave. That is, the first lens 111 may have a meniscus shape that is convex towards the object side. At least one or both of the first surface S1 and the second surface S2 in the first lens 111 may be aspherical. At least one of the first surface S1 and the second surface S2 may have an inflection point.

[0027] The second lens 112 may have a positive (+) refractive power. The second lens 112 may be made of plastic or glass material. The second lens 112 may include a third surface S3 defined as an object side and a fourth surface S4 defined as a sensor side. The third surface S3 may be convex, and the fourth surface S4 may be convex. That is, both surfaces of the second lens 112 may be convex. As another example, the third surface S3 may be convex, and the fourth surface S4 may be planar (infinity) or concave. At least one of the third surface S3 and the fourth surface S4 may be spherical or aspherical. For example, both the third surface S3 and the fourth surface S4 may be aspherical. The size of the effective diameter of the object side or sensor side of the first lens 111 may be larger than the size of the effective diameter of the object side or sensor side of the second lens 112 or the third lens 113. Here, the effective diameter may be the diameter of the effective area on the side of the object or sensor into which the light is incident. Here, the central thickness of the first lens 111 may be in the range of 2 to 4 times the central thickness of the third, fourth, and sixth lenses 113, 114, and 116, respectively.

[0028] The third lens 113 may have a negative refractive power. The third lens 113 may be made of plastic or glass. The third lens 113 may include a fifth surface S5 defined as an object side and a sixth surface S6 defined as a sensor side. The fifth surface S5 may be convex, and the sixth surface S6 may be concave. That is, the third lens 113 may have a meniscus shape that is convex towards the object side. As another example, the fifth surface S5 may be planar or concave. At least one of the fifth surface S5 and the sixth surface S6 may be spherical or aspherical. For example, both the fifth surface S5 and the sixth surface S6 may be aspherical.

[0029] The fourth lens 114 may have a positive (+) or negative (-) refractive power. The fourth lens 114 may be made of plastic or glass material. The fourth lens 114 may include a seventh surface S7 defined as an object side and an eighth surface S8 defined as a sensor side. The seventh surface S7 may be concave, and the eighth surface S8 may be convex. That is, the fourth lens 114 may have a meniscus shape that is convex on the image side. In contrast, the seventh surface S7 may be planar. At least one or both of the seventh surface S7 and the eighth surface S8 may be aspherical.

[0030] The fifth lens 115 may have a positive (+) or negative (-) refractive power. The fifth lens 115 may be made of plastic or glass material. The fifth lens 115 may include a ninth surface S9 defined as an object side and a tenth surface S10 defined as a sensor side. The ninth surface S9 may be concave, and the tenth surface S10 may be convex. That is, the fifth lens 115 may have a meniscus shape that is convex on the image side. Alternatively, the ninth surface S9 may be planar. At least one or both of the ninth surface S9 and the tenth surface S10 may be aspherical.

[0031] The sixth lens 116 may have a positive (+) or negative (-) refractive power. The sixth lens 116 may be made of a plastic material. The sixth lens 116 may include an eleventh surface S11 defined as an object side and a twelfth surface S12 defined as a sensor side. The eleventh surface S11 may be concave, and the twelfth surface S12 may be convex. That is, the sixth lens 116 may have a meniscus shape that is convex on the image side. At least one or both of the eleventh surface S11 and the twelfth surface S12 may be aspherical. At least one of the surfaces of the eleventh surface S11 and the twelfth surface S12 may have an inflection point. The radius of curvature at the center of the eleventh surface S11 of the sixth lens 116 may be greater than the radius of curvature at the center of the thirteenth surface S13 of the seventh lens 117. Here, the effective diameters of the fourth, fifth, and sixth lenses 114, 115, and 116 gradually increase from the object side to the sensor side, and for example, the effective diameter of the sixth lens 116 on the sensor side may be even larger than the effective diameter of the third lens 113 on the object side.

[0032] The seventh lens 117 may have a positive (+) or negative (-) refractive power. The seventh lens 117 may be made of plastic or glass material. The seventh lens 117 may include a thirteenth surface S13 defined as an object side and a fourteenth surface S14 defined as a sensor side. The thirteenth surface S13 may be concave, and the fourteenth surface S14 may be convex. That is, the seventh lens 117 may have a meniscus shape that is convex on the image side. At least one or both of the thirteenth surface S13 and the fourteenth surface S14 may be aspherical. At least one of the surfaces of the thirteenth surface S13 and the fourteenth surface S14 may have an inflection point. The radius of curvature at the center of the thirteenth surface S13 of the seventh lens 117 may be smaller than the radius of curvature at the center of the object sides S5, S7, S9 of the third, fourth, and fifth lenses 113, 114, and 115. The radius of curvature at the center of the 14th surface S14 of the 7th lens 117 may be smaller than the radius of curvature at the center of the sensor sides S6, S8, S10 of the 3rd, 4th, and 5th lenses 113, 114, and 115. Here, the effective diameter of the 7th lens 117 may be larger than the effective diameters of the 1st to 6th lenses 111, 112, 113, 114, 115, and 116.

[0033] The eighth lens 118 may have a positive (+) refractive power. The eighth lens 118 may include a plastic material. The eighth lens 118 may include a 15th surface S15 defined as an object side and a 16th surface S16 defined as a sensor side. On the optical axis, the 15th surface S15 may be convex and the 16th surface S16 may be concave. The 15th surface S15 and the 16th surface S16 may be aspherical. At least one or both of the 15th surface S15 and the 16th surface S16 may have at least one inflection point. In detail, the 15th surface S15 may have an inflection point around its center, and the distance inf81 from the optical axis Lx to the inflection point may be located at approximately 40% to approximately 60% of the optical axis Lx, with the edge of the eighth lens 118 as the endpoint. Here, the distance inf82 to the inflection point on the 15th plane S15 can be a position set with respect to the vertical direction of the optical axis Lx. The position of the inflection point on the 16th plane S16 can be located even closer to the edge than the position of the inflection point on the 15th plane S15. That is, the condition inf82 > inf81, which is the distance to the inflection point with respect to the optical axis Lx, can be satisfied.

[0034] The ninth lens 119 may have a negative refractive power. The ninth lens 119 may be made of a plastic material. The ninth lens 119 may include a 17th surface S17 defined as an object side and an 18th surface S18 defined as a sensor side. On the optical axis, the 17th surface S17 may be convex and the 18th surface S18 may be concave. The 17th surface S17 and the 18th surface S18 may be aspherical. Each of the 17th surface S17 and the 18th surface S18 may have at least one inflection point. At least one or both of the 17th surface S17 and the 18th surface S18 may have an inflection point. In detail, the 17th surface S17 may have an inflection point around its center, and the inflection point may be located at approximately 15% to approximately 50% of the optical axis Lx, with the optical axis Lx as the starting point and the edge of the ninth lens 109 as the ending point. Here, the position of the inflection point on the 18th surface S18 may be located at a distance inf92 with respect to the direction perpendicular to the optical axis Lx. The distance inf92 from the optical axis to the inflection point of the 18th surface S18 may be even greater than the distances inf81 and inf82 to the inflection point of the 8th lens 118, and may be located even closer to the edge than the position of the inflection point of the 17th surface S17.

[0035] Here, when comparing the linear distances from the 8th lens 118 and the 9th lens 119 to the end of the effective region with respect to the optical axis Lx, that is, the effective radii, the condition D81 < D82 < D92 can be satisfied. D81 is the linear distance from the optical axis to the end of the effective region of the 15th surface S15 of the 8th lens 118, D82 is the linear distance from the optical axis to the end of the effective region of the 16th surface S16 of the 8th lens 118, and D92 is the linear distance from the optical axis to the end of the effective region of the 18th surface S18 of the 9th lens 119. Thereby, the light incident from the 8th lens 118 can be refracted further outward in the direction with respect to the optical axis. When comparing the distances of the optical axis Lx from the 8th lens 118 and the 9th lens 119 to the end of the effective region, the condition D81 < D82 < D92 < D91 can be satisfied. D81 is the distance in the optical axis direction from the center (optical axis position) of the 15th surface S15 of the 8th lens 118 to the end of the effective region, D82 is the distance in the optical axis direction from the center (optical axis position) of the 16th surface S16 to the end of the effective region, D91 is the distance in the optical axis direction from the center (optical axis position) of the 17th surface S17 of the 9th lens 119 to the end of the effective region, and D92 is the distance in the optical axis direction from the center (optical axis position) of the 18th surface S18 to the end of the effective region.

[0036] The optical filter 192 can include at least one of optical filters such as an infrared filter and a cover glass. The optical filter 192 can pass light in a set wavelength band and filter light in a different wavelength band. When the optical filter 192 includes an infrared filter, it can block the transmission of radiant heat emitted from external light to the image sensor. Also, the optical filter 192 can transmit visible light and reflect infrared light. The image sensor 190 can sense light. The image sensor 190 can include a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor), etc.

[0037] The total length TTL of the optical system may be 7 mm or more, for example, in the range of 7 mm to 12 mm or 8 mm to 11.5 mm. The TTL is the distance from the center of the object side of the first lens 111 to the image sensor 190. The distance BFL from the center of the sensor-side 18th surface S18 of the 9th lens 119 to the image sensor 190 may be 1 mm or more, for example, in the range of 1 mm to 2 mm or 1 mm to 1.7 mm. The vertical distance Img from the optical axis of the image sensor 190 to 1.0 field may be 6 mm or more, for example, in the range of 6 mm to 10 mm or 6.5 mm to 9 mm. The total focal length F of the optical system may be 5 mm or more, for example, in the range of 5 mm to 9 mm or 6 mm to 8.2 mm.

[0038] In the optical systems of the first to third embodiments, the first to 18 surfaces S1 to S18 of the first to 9th lenses 111, 112, 113, 114, 115, 116, 117, 118, and 119 can all be aspherical. With respect to the optical axis, the radius of curvature (converted to absolute value) of each of the first to 18 surfaces S1 to S18 may be such that the radius of curvature of the 9th surface S9 is the largest, the radius of curvature of the 18th surface S18 is the smallest, and the radius of curvature of the 7th surface S7 or the 8th surface S8 is the second largest.

[0039] Of the first to ninth lenses 111, 112, 113, 114, 115, 116, 117, 118, and 119, among the first to 18th surfaces S1 to S18, there may be four or more lenses with a convex object side, four or more lenses with a concave object side, five or more lenses with a convex sensor side, and four or more lenses with a concave sensor side, all on the optical axis. Looking at the Abbe numbers of the first to ninth lenses 111, 112, 113, 114, 115, 116, 117, 118, and 119, there may be six or more lenses with an Abbe number of 50 or more, and three or fewer lenses with an Abbe number less than 50. For example, the Abbe numbers of the first lens 111, the third lens 113, the fifth lens 115, the seventh lens 117, the eighth lens 118, and the ninth lens 119 are 50 or greater, the Abbe numbers of the third lens 113 and the sixth lens 116 may be 30 or less, and the Abbe number of the eighth lens 118 may be less than 35 and greater than 20. Looking at the refractive indices of the first to ninth lenses 111, 112, 113, 114, 115, 116, 117, 118, and 119, there may be three or more lenses with a refractive index of 1.6 or greater at 587 nm, and there may be six or fewer lenses with a refractive index of less than 1.6. For example, at 587 nm, the refractive indices of the third lens 113, the sixth lens 116, and the eighth lens 118 are 1.6 or greater, while the refractive indices of the first and second lenses 111 and 112, the fourth and fifth lenses 114 and 115, and the seventh and ninth lenses 117 and 119 may be less than 1.6. The refractive indices of the third lens 113 and the sixth lens 116 have the highest refractive indices among the lenses and may be 1.65 or greater.

[0040] Looking at the thicknesses of the central portions of the first to ninth lenses 111, 112, 113, 114, 115, 116, 117, 118, 119, there are three or more lenses with a central portion thickness of 0.6 mm or more, and there can be six or fewer lenses with a central portion thickness of less than 0.6 mm. For example, the thicknesses T1, T2, T3 of the central portions of the first to third lenses 111, 112, 113 can satisfy the condition T3 < T2 < T1, and the thicknesses T4, T5, T6 of the central portions of the fourth to sixth lenses 114, 115, 116 can satisfy the condition T4 ≤ T6 ≤ T3 < T5. The thicknesses of the central portions of the third and fourth lenses 113, 114 satisfy the relationship T4 < T3, and the thicknesses T7, T8, T9 of the central portions of the seventh to ninth lenses 117, 118, 119 satisfy the condition T3 < T7 < T8 < T9. Here, T1 to T9 are the thicknesses of the central portions of the first to ninth lenses 111 to 119.

[0041] Looking at the intervals on the optical axis between two adjacent lenses among the first to ninth lenses 111, 112, 113, 114, 115, 116, 117, 118, 119, it satisfies T67 ≤ T34 < T89. T67 is the optical axis interval between the adjacent sixth and seventh lenses 116, 117, T34 is the optical axis interval between the adjacent third and fourth lenses 113, 114, and T89 is the optical axis interval between the adjacent eighth and ninth lenses 118, 119. Here, T34 is 0.4 mm or more, greater than the optical axis interval between the first and second lenses 111, 112, and T89 can be greater than the thickness of the central portion of the second lens 112 and greater than the sum of the thicknesses of the central portions of the first and second lenses 111, 112, and can be in the range of 1 mm or more, for example, 1 mm to 2 mm. Also, looking at the interval between the eighth lens 118 and the ninth lens 119, the optical axis interval between two adjacent centers on the optical axis may be greater than the interval between two adjacent peripheral portions.

[0042] As shown in FIG. 5, a reflecting member 101 can be disposed on the incident side of the first lens 111. The reflecting member 101 can reflect the light incident through the optical axis Ly orthogonal to the optical axis Lx of the first lens 111 to the ninth lens 119 to the first lens 111. The reflecting member 101 can include a prism, that is, a triangular or rectangular prism.

[0043] Table 1 shows the values ​​for the radius of curvature, thickness, spacing, refractive index, and Abbe number of each lens surface in the first embodiment.

[0044] [Table 1]

[0045] In Table 1, the thickness is the thickness (mm) at the center of each lens, and the spacing is the spacing (mm) between two adjacent lenses. S19 indicates the incident side of the optical filter, and S20 indicates the exit side of the optical filter. Table 2 shows the aspheric coefficient values ​​for the surface of each lens in Figure 1.

[0046] [Table 2] TIFF0007869791000003.tif214170TIFF0007869791000004.tif121170

[0047] Figure 6 is an analysis graph showing the longitudinal spherical aberration, astigmatism, and distortion of the optical system in Figure 1. The optical system according to the first embodiment can exhibit spherical aberration as shown in Figure 6(A), which is a phenomenon in which the focal point of light passing through different parts of the lens (e.g., the center and the periphery) changes. The horizontal axis shows the degree of longitudinal spherical aberration, and the vertical axis shows the normalized distance from the center of the optical axis, and can show the change in longitudinal spherical aberration with respect to the wavelength of light. Longitudinal spherical aberration can be shown, for example, for light with wavelengths of approximately 656.2725 nm (nanometer), approximately 587.5618 nm, approximately 546.0740 nm, approximately 486.1327 nm, or approximately 435.8343 nm, respectively. Figure 6(A) shows that the longitudinal spherical aberration of the optical system is limited to within +0.025 to -0.025, demonstrating stable optical characteristics. Figure 6(B) is a graph showing astigmatism in the optical system according to the first embodiment. Astigmatism occurs when the tangential plane (or meridian plane) and sagittal plane of a lens have different radii, causing the focal points of light passing through the vertical and horizontal directions to be misaligned. The astigmatism of the optical system is a result obtained at a wavelength of approximately 546.0740 nm, where the solid line represents tangential astigmatism (e.g., meridian plane curvature), and the dotted line represents sagittal astigmatism (e.g., sagittal plane curvature). As can be seen through Figure 6(B), the astigmatism is limited to within +0.050 to -0.050, confirming that the optical characteristics are stable.

[0048] Figure 6(C) is a graph showing the distortion aberration of the optical system of the first embodiment. Distortion aberration occurs because the optical magnification changes with distance from the optical axis OI, and the image formed on the actual image plane (e.g., 190 in Figure 1) may appear larger or smaller than the image formed on the theoretical image plane. In Figure 6(C), the distortion of the optical system is the result obtained at a wavelength of approximately 546.0740 nm, and the image captured through the optical system may exhibit some distortion at points deviated from the optical axis OI. However, such distortion is of a level that is generally observed in optical devices using lenses, and the distortion rate is less than approximately 3%, providing good optical characteristics.

[0049] Figure 7 shows the distortion grid generated when light is emitted from the optical system according to the first embodiment. Here, it can be confirmed that distortion occurs on the left and right outer edges in the horizontal direction (Horizontal FOV (Field of View)). The distortion on the left and right outer edges may be greater than the distortion that occurs on the top and bottom outer edges in the vertical direction (vertical FOV). Figure 8 is an analysis graph showing the lateral aberration in the region where the relative field height on the optical axis is 0.0 to 1.0 in the tangential field curvature and sagittal field curvature of the optical system shown in Figure 1. It can be confirmed that an optical system with good lateral aberration correction can be obtained.

[0050] The second embodiment is shown in Figure 2. Table 3 below shows the values ​​for the radius of curvature, thickness, spacing, refractive index, and Abbe number of each lens surface in the second embodiment shown in Figure 2.

[0051] [Table 3]

[0052] In Table 3, the thickness is the thickness (mm) of the center of each lens in Figure 2, and the spacing is the spacing (mm) between two adjacent lenses. S19 indicates the incident side of the optical filter, and S20 indicates the outgoing side of the optical filter.

[0053] Table 4 shows the aspheric coefficients for each lens surface in Figure 2.

[0054] [Table 4] TIFF0007869791000007.tif213170TIFF0007869791000008.tif111170

[0055] Figure 9 is an analysis graph showing the longitudinal spherical aberration, astigmatism, and distortion of the optical system in Figure 2. The optical system according to the second embodiment can exhibit spherical aberration as shown in Figure 9(A), which is a phenomenon in which the focal point of light passing through different parts of the lens (e.g., the center and the periphery) changes. The horizontal axis shows the degree of longitudinal spherical aberration, and the vertical axis shows the normalized distance from the center of the optical axis, and can show the change in longitudinal spherical aberration with respect to the wavelength of light. Longitudinal spherical aberration can be shown, for example, for light with wavelengths of approximately 656.2725 nm (nanometer), approximately 587.5618 nm, approximately 546.0740 nm, approximately 486.1327 nm, or approximately 435.8343 nm, respectively. Figure 9(A) shows that the longitudinal spherical aberration of the optical system is limited to within +0.025 to -0.025, demonstrating stable optical characteristics. Figure 9(B) is a graph showing astigmatism in the optical system according to the second embodiment. Astigmatism can occur when the tangential plane (or meridian plane) and sagittal plane of a lens have different radii, resulting in a misalignment of the focal points of light passing through the vertical and horizontal directions. The astigmatism of the optical system is a result obtained at a wavelength of approximately 546.0740 nm, where the solid line represents tangential astigmatism (e.g., meridian plane curvature), and the dotted line represents sagittal astigmatism (e.g., sagittal plane curvature). As can be seen through Figure 9(B), the astigmatism is limited to within +0.050 to -0.050, confirming that the optical characteristics are stable.

[0056] Figure 9(C) is a graph showing the distortion aberration of the optical system of the second embodiment. Distortion aberration occurs because the optical magnification changes with distance from the optical axis OI, and the image formed on the actual image plane (e.g., 190 in Figure 1) may appear larger or smaller than the image formed on the theoretical image plane. In Figure 9(C), the distortion of the optical system is the result obtained at a wavelength of approximately 546.0740 nm, and the image captured through the optical system may exhibit some distortion at points deviated from the optical axis OI. However, such distortion is of a level that is generally observed in optical devices using lenses, and the distortion rate is less than approximately 3%, providing good optical characteristics.

[0057] Figure 10 shows the distortion grid generated when light is emitted from the optical system according to the second embodiment. Here, it can be confirmed that distortion occurs on the left and right outer edges in the horizontal direction (Horizontal FOV (Field of View)). The distortion on the left and right outer edges may be greater than the distortion formed on the upper and lower outer edges in the vertical direction (vertical FOV). Figure 11 is an analysis graph showing the lateral aberration in the region where the relative field height on the optical axis is 0.0 to 1.0 in the tangential field curvature and sagittal field curvature of the optical system shown in Figure 2. It can be confirmed that an optical system with good lateral aberration correction can be obtained.

[0058] The third embodiment is shown in Figure 3, and Table 5 shows the data for the radius of curvature, thickness, spacing, refractive index, and Abbe number of each lens surface in the third embodiment shown in Figure 3.

[0059] [Table 5]

[0060] In Table 5, the thickness is the thickness (mm) of the center of each lens in Figure 3, and the spacing is the spacing (mm) between two adjacent lenses. S19 indicates the incident side of the optical filter, and S20 indicates the exit side of the optical filter. Table 6 shows the aspheric coefficient values ​​for the surface of each lens in Figure 3.

[0061] [Table 6] TIFF0007869791000011.tif215170TIFF0007869791000012.tif113170

[0062] Figure 12 is an analysis graph showing the longitudinal spherical aberration, astigmatism, and distortion of the optical system in Figure 3. The optical system according to the third embodiment can exhibit spherical aberration as shown in Figure 12(A), which is a phenomenon in which the focal point of light passing through different parts of the lens (e.g., the center and the periphery) changes. The horizontal axis shows the degree of longitudinal spherical aberration, and the vertical axis shows the normalized distance from the center of the optical axis, and can show the change in longitudinal spherical aberration with respect to the wavelength of light. Longitudinal spherical aberration can be shown, for example, for light with wavelengths of approximately 656.2725 nm (nanometer), approximately 587.5618 nm, approximately 546.0740 nm, approximately 486.1327 nm, or approximately 435.8343 nm, respectively. Figure 12(A) shows that the longitudinal spherical aberration of the optical system is limited to within +0.025 to -0.025, demonstrating stable optical characteristics. Figure 12(B) is a graph showing astigmatism in the optical system according to the second embodiment. Astigmatism can occur when the tangential plane (or meridian plane) and sagittal plane of a lens have different radii, resulting in a misalignment of the focal points of light passing through the vertical and horizontal directions. The astigmatism of the optical system is a result obtained at a wavelength of approximately 546.0740 nm, where the solid line represents tangential astigmatism (e.g., meridian plane curvature), and the dotted line represents sagittal astigmatism (e.g., sagittal plane curvature). As can be seen through Figure 12(B), the astigmatism is limited to within +0.050 to -0.050, confirming that the optical characteristics are stable.

[0063] Figure 12(C) is a graph showing the distortion aberration of the optical system of the third embodiment. Distortion aberration occurs because the optical magnification changes with distance from the optical axis OI, and the image formed on the actual image plane (e.g., 190 in Figure 1) may appear larger or smaller than the image formed on the theoretical image plane. In Figure 12(C), the distortion of the optical system is the result obtained at a wavelength of approximately 546.0740 nm, and the image captured through the optical system may exhibit some distortion at points deviated from the optical axis OI. However, such distortion is of a level that is generally observed in optical devices using lenses, and the distortion rate is less than approximately 3%, providing good optical characteristics.

[0064] Figure 13 shows the distortion grid generated when light is emitted from the optical system according to the third embodiment. Here, it can be confirmed that distortion occurs on the left and right outer edges in the horizontal direction (Horizontal FOV (Field of View)). The distortion on the left and right outer edges may be greater than the distortion formed on the upper and lower outer edges in the vertical direction (vertical FOV). Figure 14 is an analysis graph showing the lateral aberration in the region where the relative field height on the optical axis is 0.0 to 1.0 in the tangential field curvature and sagittal field curvature of the optical system shown in Figure 3. It can be confirmed that an optical system with good lateral aberration correction can be obtained.

[0065] As shown in the first to third embodiments above, each lens 111 to 119 can be made entirely of plastic, and each lens surface can have an aspherical coefficient.

[0066] In the first to third embodiments of the present invention, the center thickness of the second lens 112 is the thickest, and may be, for example, 0.7 mm or more. The first spacing between the third lens 113 and the fourth lens 114 along the optical axis, and the second spacing between the eighth lens 118 and the ninth lens 119 may be greater than the spacing between the first lens 111 and the second lens 112 or the optical axial spacing between the second lens 112 and the third lens 113, or greater than the optical axial spacing between the fourth to sixth lenses 114, 115, and 116. The first and second spacings may be, for example, 0.7 mm or more. The first spacing between the third lens 113 and the fourth lens 114 along the optical axis may be smaller than the second spacing between the eighth lens 118 and the ninth lens 119.

[0067] In embodiments of the present invention, when nine or more lenses 111 to 119 are stacked, in order to prevent an increase in the total distance TTL of the optical system, the stacked structure of lenses with relatively large effective diameters, such as the 7th, 8th, and 9th lenses 117, 118, and 119, can be set to the following conditions.

[0068] Referring to Figure 4, comparing the difference in distance (in the optical axis direction) between the edge sides of two adjacent lenses 117, 118, and 119 among the seventh, eighth, and ninth lenses, the condition (E81-E71)<(E91-E81) can be satisfied. E71 is a straight line extending from the edge of the thirteenth surface S13 of the seventh lens 117 in a direction perpendicular to the optical axis Lx, or a straight line connecting the edges of the side surface of the object; E81 is a straight line extending from the edge of the fifteenth surface S15 of the eighth lens 118 in a direction perpendicular to the optical axis Lx, or a straight line connecting the edges of the side surface of the object; and E91 is a straight line extending from the edge of the seventeenth surface S17 of the ninth lens 119 in a direction perpendicular to the optical axis Lx, or a straight line connecting the edges of the side surface of the object.

[0069] Here, looking at the distance in the optical axis direction, a straight line E81 extending in a direction orthogonal to the optical axis direction along the edge of the 15th surface S15 of the 8th lens 118 is closer to the straight line E71 than a straight line (for example, a straight line orthogonal to the optical axis) passing through the center C72 of the 14th surface S14 of the 7th lens 117, or protrudes toward the 1st lens 111 and is the same as a straight line passing through the midpoint C73 between the centers C71 and C72 on both sides of the 7th lens 117, or may be even closer to the straight line E71 or the 1st lens 111.

[0070] Here, the straight line E81 passing through the object-side edge of the 8th lens 118 is the first distance B1 from a straight line passing through the midpoint C73 between both sides of the 7th lens 117, and is the second distance B2 from a straight line passing through the sensor-side 14th surface S14 of the 7th lens 117. The distance between the straight line E91 on the edge side of the object-side 17th surface S17 of the 9th lens 119 and a straight line passing through the midpoint C83 between the centers C81 and C82 on both sides of the 8th lens 118 may be the third distance B3. The condition that the distance B3 < B1 < B2 is satisfied, and the B1 may be in the range of 80% or more of the thickness T7 of the 7th lens 17, for example, in the range of 80% to 120%. Thereby, the outer upper part of the 8th lens 118 is provided in a shape surrounding the object side of the 7th lens 117, and the incident-side 15th surface S15 of the 8th lens 118 allows the light refracted through the effective area of the exit-side 14th surface S14 of the 7th lens 117 to be effectively incident, reducing light loss, providing light up to the angular region of the image sensor 190, and preventing a decrease in resolution.

[0071] The optical systems according to the first to third embodiments of the present invention can satisfy at least one or two or more of the following mathematical formulas to be described. Thereby, the optical systems according to the first to third embodiments can have an optically improved effect.

[0072] Table 7 can satisfy the following conditions in the optical systems of the first to third embodiments.

[0073]

Table 7

[0074] In Table 7 above, F is the total focal length, f29 is the combined focal length from the second lens 112 to the ninth lens 119, f12 is the combined focal length of the first lens 111 and the second lens 112, f13 is the combined focal length of the first lens 111 and the third lens 113, L2R1 is the radius of curvature (mm) of the object side S3 of the second lens 112, L2R2 is the radius of curvature (mm) of the sensor side S4 of the second lens 112, and L3R1 is the radius of curvature (mm) of the object side S of the third lens 113. 5 is the radius of curvature (mm), L3R2 is the radius of curvature of the sensor side S6 of the third lens 113, G2 is the refractive index of the second lens 112 at 587nm, G3 is the refractive index of the third lens 113 at 587nm, T1, T2, T3 are the center thicknesses (mm) of the first lens 111, the second lens 112, and the third lens 113, and f1, f2, f3, f4, f5, f6, f7, f8, f9 are the focal lengths of the first to ninth lenses 111 to 119, respectively. From Table 7 above, by comparing each value with different values ​​based on that value, if there is a difference of 0.1 mm or less, it can be explained as being the same or larger or the same or smaller. Table 8 can be shown by equations 1 to 27, reflecting the characteristics of each lens in the optical system. The optical systems of the first to third embodiments can satisfy at least one, two or more, or all of the following equations 1 to 27.

[0075] [Table 8] TIFF0007869791000016.tif68157

[0076] Table 9 can be shown, based on Table 8, with detailed numerical ranges for each formula in the optical systems of the first to third embodiments.

[0077] [Table 9] TIFF0007869791000018.tif77159

[0078] For the formula 1, 0 < BFL / TTL < 0.3 can provide a high-resolution optical system by providing TTL with a length longer than that of BFL. For the formula 2, 0 < BFL / Img < 0.3 shows the relationship between the distance from the center of the image side 18th surface S18 of the 9th lens 119 to the image sensor 190 and the distance from the optical axis Lx to 1.0F, and can provide an image sensor 190 with high resolution and a large size satisfying (BFL × 2) < Img.

[0079] The relationship between the overall length of the optical system and the effective focal length is limited by 0.5 < F / TTL < 1.2 in formula 3. By 0.5 < TTL / (Img × 2) < 0.8 in formula 4, the overall length TTL can be provided within the range of 50% - 80% of the diagonal length of the image sensor 190.

[0080] In formula 14, |L2R2| represents the absolute value of the radius of curvature of the sensor side surface S4 of the 2nd lens 112, and it may be larger than the radius of curvature L2R1 of the object side surface S3 of the 2nd lens 112. In formula 15, |L3R1| represents the absolute value of the radius of curvature of the object side surface S5 of the 3rd lens 113, and it may be larger than the radius of curvature L3R2 of the sensor side surface S6 of the 3rd lens 113.

[0081] The optical performance can be improved by the relationship of the thicknesses of the central parts of the 1st, 2nd, and 3rd lenses 111, 112, and 113 in formulas 17 and 18. By formulas 19 and 20, the refractive power of the incident light can be improved through the relationship of the straight-line distance inf81 from the optical axis to the inflection point of the object side surface S15 of the 8th lens 118, the straight-line distance inf82 from the optical axis to the inflection point of the sensor side surface S16 of the 8th lens 118, and the straight-line distance inf92 from the optical axis to the inflection point of the sensor side surface S18 of the 9th lens 119.

[0082] According to equations 21-23, the straight-line distance D81 from the optical axis to the end of the effective area of ​​the object side S15 of the eighth lens 118, the straight-line distance D82 to the end of the effective area of ​​the sensor side S16 of the eighth lens 118, and the straight-line distance D92 to the end of the effective area of ​​the sensor side S18 of the ninth lens 119 can be made larger than the straight-line distances inf81, inf82, and inf92 to the inflection points of the eighth and ninth lenses 118 and 119. This allows the effective diameter to be provided further outward than the inflection points, thereby improving the refractive power of light.

[0083] According to equations 24-27, the refractive power of light in the eighth and ninth lenses 118 and 119 can be improved through the relationship between the optical axis distance from the center of the object side S15 and sensor side S16 of the eighth lens 118 to the end of the effective area, the distance from the center of the object side S17 and sensor side S18 of the ninth lens 9 to the end of the effective area, and the straight-line distance to the end of the effective area along the optical axis.

[0084] The optical systems according to the first to third embodiments of the present invention can satisfy at least one, two or more, five or more, or all of the equations 1 to 27. In this case, the optical system can embody a high-quality and high-resolution imaging lens system. Furthermore, at least one of the equations 1 to 27 can block unwanted light entering the optical system, correct aberrations, and improve the performance of the optical system.

[0085] Figure 15 is a perspective view showing an example of a mobile device to which an optical system according to an embodiment of the present invention is applied. As shown in Figure 15, the mobile terminal 1500 may include a camera module 1520, a flash module 1530, and an autofocus device 1510 provided on one or the back. Here, the autofocus device 1510 may include a surface-emitting laser element and a light-receiving unit as an emitting layer. The flash module 1530 may include an emitter that emits light inside. The flash module 1530 may be operated by the camera operation of the mobile terminal or by user control. The camera module 1520 may include an image capture function and an autofocus function. For example, the camera module 1520 may include an image-based autofocus function. The autofocus device 1510 may include a laser-based autofocus function. The autofocus device 1510 may be mainly used in conditions where the image-based autofocus function of the camera module 1520 is reduced, such as close proximity of 10m or less or in dark environments.

[0086] The features, structures, and effects described in the examples 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, and effects exemplified in each embodiment can be combined or modified and implemented in other embodiments by a person with ordinary skill in the art to which the embodiment belongs. Therefore, such combinations and modifications should be interpreted as being included within the scope of the embodiments of the present invention. In addition, although the above has focused on embodiments, these are merely examples and do not limit the present invention. A person with ordinary skill in the art to which the present invention belongs will understand that a variety of modifications and applications not exemplified above are possible without departing from the essential characteristics of these embodiments. For example, each component specifically shown in the embodiments can be modified and implemented. And the differences related to such modifications and applications should be interpreted as being included within the scope of the present invention as defined in the attached claims.

Claims

1. It consists of a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, and a ninth lens, which are sequentially arranged along the optical axis from the object side to the sensor side. The first lens has a positive refractive power and the side surface of the object is convex. The second lens has a positive refractive power, the object side is convex, and the sensor side is convex. The third lens has negative refractive power and the sensor side is concave. The fourth lens has a concave side surface, The fifth lens has a positive refractive power, The sixth lens has a negative refractive power, The seventh lens has a positive refractive power, The eighth lens has a positive refractive power, and at least one of the object side and the sensor side has at least one inflection point. The ninth lens has a negative refractive power, and the object side and the sensor side have at least one inflection point. The ninth lens has a convex side surface of the object and a concave side surface of the sensor. The central thickness of the second lens is thicker than the central thickness of the ninth lens. An optical system in which the refractive index of the third lens is greater than that of the fourth lens.

2. The optical system according to claim 1, wherein the central thickness of the second lens is greater than the central thicknesses of the first, third to sixth lenses, and so on.

3. The optical system according to claim 1, wherein the refractive indices of the third, sixth, and eighth lenses are greater than the refractive indices of the first, second, fifth, seventh, and ninth lenses.

4. The optical system according to any one of claims 1 to 3, wherein the Abbe numbers of the first, second, fourth, fifth, seventh, and ninth lenses are 50 or more, and the Abbe numbers of the third and sixth lenses are less than 30.

5. The optical system according to any one of claims 1 to 4, wherein the fourth lens has a negative refractive power.

6. The ninth lens includes an image sensor on the sensor side and an optical filter between the image sensor and the ninth lens. The optical system satisfies equations 1 and 2, [Math 1] 0<BFL / TTL<0.3 [Math 2] 0 < BFL / Img < 0.3 The optical system according to any one of claims 1 to 5, wherein BFL is the distance from the center of the ninth lens on the sensor side to the image sensor, TTL is the distance from the center of the object side of the first lens to the image sensor, and Img is the distance from the optical axis to the end of the diagonal in the image sensor.

7. The ninth lens includes an image sensor on the sensor side and an optical filter between the image sensor and the ninth lens. The optical system satisfies equations 3, 4, and 5. [Math 3] 0.5<F / TTL<1.2 [Math 4] 0.5<TTL / (Img×2)<0.8 [Math 5] 0.5<TTL / (D92×2)<1.2 The optical system according to any one of claims 1 to 6, wherein TTL is the distance from the center of the side surface of the first lens object to the image sensor, F is the total effective focal length of the optical system, Img is the distance from the optical axis to the end of the diagonal in the image sensor, and D92 is the distance from the center of the sensor side surface of the ninth lens to the end of the effective region in the optical axis.

8. The optical system according to any one of claims 1 to 7, wherein the radius of curvature of the object side surface of the second lens is L2R1, and when the absolute value of the radius of curvature of the sensor side surface of the second lens is defined as |L2R2|, the condition 0 < L2R1 / |L2R2| < 0.5 is satisfied.

9. When the absolute value of the radius of curvature of the object side of the third lens is |L3R1| and the radius of curvature of the sensor side of the third lens is L3R2, the relationship 0.2 < L3R2 / |L3R1| < 1 is satisfied. The optical system according to any one of claims 1 to 8, wherein the radius of curvature of the object side surface of the fifth lens is the largest of the absolute values ​​of the radii of curvature of the object side surfaces of the first to ninth lenses and the sensor side surfaces.

10. The optical system according to any one of claims 1 to 9, wherein when the refractive index of the second lens at 587 nm is G2 and the refractive index of the third lens at 587 nm is G3, the relationship 0.7 < G2 / G3 < 1.2 is satisfied.

11. The optical system according to any one of claims 1 to 10, wherein the central thickness of the first lens is T1, the central thickness of the second lens is T2, and the central thickness of the third lens is T3, satisfying the relationships 0.2 < T3 / T2 < 1 and 0.2 < T1 / T2 < 1.

12. The first lens has a concave side surface of the sensor, The eighth lens has a positive refractive power, the object side is convex, and the sensor side is concave. The edge of the object side of the eighth lens protrudes toward the first lens from the center of the optical axis of the object side of the eighth lens, The straight line connecting the edges of the object sides of the eighth lens is the same as, or even closer to, the straight line perpendicular to the optical axis midway between the object side and the sensor side of the seventh lens, The optical system according to any one of claims 1 to 11, wherein the central thickness of the second lens is greater than the central thickness of the ninth lens.

13. The optical system according to claim 12, wherein the straight line connecting the edges of the object side surface of the eighth lens is located closer to the first lens than the straight line perpendicular to the optical axis at the center of the object side surface of the seventh lens.

14. The distance between the fourth lens and the fifth lens along the optical axis is greater than the first distance between the first lens and the second lens. The optical system according to claim 12 or 13, wherein the second interval between the eighth lens and the ninth lens along the optical axis is greater than the first interval.

15. The optical system according to claim 14, wherein the first interval and the second interval are 0.4 mm or more.

16. The optical system according to any one of claims 13 to 15, wherein the central thickness of the second lens is in the range of 2 to 4 times the central thickness of the third lens.

Images