Optical system and camera module

Abstract

An optical system according to the present embodiment comprises first to eighth lenses disposed along the optical axis, wherein the first lens has negative (-) refractive power, the second lens has positive (+) refractive power, the third lens has positive (+) refractive power, the fourth lens has negative (-) refractive power, the sixth lens has positive (+) refractive power, and on the optical axis, the second lens has a meniscus shape that is concave toward the sensor side, and on the optical axis, the third lens have a biconvex shape.

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] ADAS (Advanced Driving Assistance System) is an advanced driver assistance system that assists the driver in driving. It consists of sensing the situation ahead, judging the situation based on the sensed results, and controlling the vehicle's behavior based on the situation judgment. For example, ADAS sensor devices detect a vehicle ahead and recognize lanes. After the target lane, target speed, and forward target are determined, the vehicle's ESC (Electrical Stability Control), EMS (Engine Management System), and MDPS (Motor Driven Power Steering) are controlled. Representative examples of ADAS can be implemented as automatic parking systems, low-speed city driving assistance systems, and blind spot warning systems.

[0003] Sensor devices for detecting the situation ahead in ADAS include GPS sensors, laser scanners, forward radar, Lidar, etc., and the most representative one is a camera for taking pictures of the front, rear, and sides of the vehicle.

[0004] These cameras can be placed outside or inside a vehicle to detect the vehicle's surroundings. Furthermore, the cameras can be placed inside the vehicle to detect the driver and passengers. For example, the camera can photograph the driver from a position adjacent to the driver and detect the driver's health, drowsiness, and drinking status. Furthermore, the camera can photograph the passenger from a position adjacent to the passenger and detect the passenger's sleepiness, health, and other conditions, and provide the driver with information about the passenger.

[0005] In particular, the most crucial element for capturing an image from a camera is the imaging lens that forms the image. Recently, interest in high-performance features such as high image quality and high resolution has been increasing, and research is being conducted on optical systems comprising multiple lenses to achieve these features. However, there is a problem in that the characteristics of the optical system change when the camera is exposed to harsh environments, such as high temperature, low temperature, moisture, or high humidity, either inside or outside the vehicle. In this case, the camera faces the problem of difficulty in uniformly achieving excellent optical and aberration characteristics.

[0006] Therefore, a new optical system and camera that can solve the above-described problems are required.

[0007] The present invention seeks to provide an optical system and camera module having improved optical characteristics.

[0008] The present invention seeks to provide an optical system and camera module having excellent optical performance in low-temperature to high-temperature environments.

[0009] The present invention seeks to provide an optical system and camera module capable of preventing or minimizing changes in optical properties over a wide temperature range.

[0010] In order to solve the above technical problem, an optical system according to the present embodiment includes first to eighth lenses arranged along an optical axis, wherein the first lens has negative (-) refractive power, the second lens has positive (+) refractive power, the third lens has positive (+) refractive power, the fourth lens has negative (-) refractive power, and the sixth lens has positive (+) refractive power, and the second lens has a concave meniscus shape toward the sensor on the optical axis, and the third lens has a convex shape on both sides on the optical axis.

[0011] The effective diameter may become smaller as you go from the first lens to the second lens, and the effective diameter may become larger as you go from the fourth lens to the fifth lens.

[0012] Among the first to eighth lenses, a plurality of lenses sequentially arranged are made of glass, the remaining lenses sequentially arranged are made of plastic, and the average of the effective diameters of the plurality of lenses having the plastic material may be larger than the effective diameter of the glass material lens arranged on the object side of the plastic material lens.

[0013] Among the first to eighth lenses, a plurality of lenses sequentially arranged are made of glass, the remaining lenses sequentially arranged are made of plastic, and among the first to eighth lenses, the effective diameter of the lens made of glass arranged on the object side of the lens made of plastic may be the largest.

[0014] The first to third lenses may be made of glass, and the fourth to eighth lenses may be made of plastic.

[0015] The fifth lens may have positive (+) refractive power, the seventh lens may have negative (-) refractive power, and the eighth lens may have positive (+) refractive power.

[0016] The following condition can be satisfied. <Condition> 0.4 < n2-n3 < 0.6 (In the above condition, n2 is the refractive index of the second lens, and n3 is the refractive index of the third lens.)

[0017] The following condition can be satisfied. <Condition> 20 < |L2R1| < 110 (In the above condition, L2R1 means the radius of curvature of the object-side surface of the second lens.)

[0018] In order to solve the above technical problem, an optical system according to another embodiment of the present invention includes first to eighth lenses arranged along an optical axis, wherein the first lens has negative (-) refractive power, the second lens has positive (+) refractive power, the third lens has positive (+) refractive power, the fourth lens has negative (-) refractive power, and the sixth lens has positive (+) refractive power, and among the first to eighth lenses, a plurality of lenses arranged sequentially are made of glass, and the remaining lenses arranged sequentially are made of plastic.

[0019] Among the first to eighth lenses, the effective diameter of the third lens may be the smallest.

[0020] The object-side and sensor-side surfaces of the seventh lens and the eighth lens may have inflection points.

[0021] In the above optical axis, the second lens may have a concave meniscus shape toward the sensor.

[0022] The following condition can be satisfied. <Condition> 0.4 < n_max-n_min < 0.6 (In the above condition, n_max is the refractive index of the lens with the largest refractive index in the optical system, and n_min is the refractive index of the lens with the largest refractive index in the optical system.)

[0023] The following condition can be satisfied. <Condition> 1.8 < n2 < 2 (In the above condition, n2 represents the refractive index of the second lens.)

[0024] The following conditions can be satisfied. <Conditional expression> L3R1 > 0, L3R2 < 0, 1.4 < n3 < 1.6 (In the above conditional expression, L3R1 is the radius of curvature of the object-side surface of the third lens, L3R2 is the radius of curvature of the sensor-side surface of the third lens, and n3 represents the refractive index of the third lens.)

[0025] An optical system and camera module according to an embodiment may have improved optical characteristics. Specifically, in the optical system according to an embodiment, a plurality of lenses may have set thicknesses, refractive powers, and spacings from adjacent lenses. Accordingly, the optical system and camera module according to the embodiment may have improved MTF characteristics, aberration control characteristics, resolution characteristics, etc. within a set field of view range, and may have good optical performance in the periphery of the field of view.

[0026] In addition, the optical system and camera module according to the embodiment can have good optical performance in a low temperature to high temperature range (-40℃ to 105℃). Specifically, a plurality of lenses included in the optical system can have set materials, refractive powers, and refractive indices. Accordingly, when the refractive index of each lens changes according to a temperature change and the focal length of each lens changes due to this, mutual compensation can be made by the plastic lens and the glass lens. That is, the optical system can effectively perform refractive power distribution in a low temperature to high temperature range, and can prevent or minimize changes in optical characteristics in a low temperature to high temperature range. Therefore, the optical system and camera module according to the embodiment can maintain improved optical characteristics in various temperature ranges.

[0027] Furthermore, the optical system and camera module according to the embodiment can satisfy the set angle of view and implement excellent optical characteristics through a combination of plastic and glass lenses. This allows the optical system to provide a slimmer vehicle camera module. Accordingly, the optical system and camera module can be used in various applications and devices, and can maintain excellent optical characteristics even in harsh temperature environments, such as when exposed to the exterior of a vehicle or in the high temperatures of a vehicle interior during the summer.

[0028] FIG. 1 is a side cross-sectional view of an optical system and a camera module having the same according to a first embodiment.

[0029] Figure 2 is a table showing the aspherical coefficient of the aspherical lens surface among the lenses in the optical system of Figure 1.

[0030] Fig. 3 is a table showing the Sag values ​​of the lens surfaces of the first to eighth lenses in the optical system of Fig. 1.

[0031] Fig. 4 is a graph showing data on the diffraction MTF (Modulation Transfer Function) of the optical system of Fig. 1 at room temperature.

[0032] Fig. 5 is a graph showing data on the aberration characteristics of the optical system of Fig. 1 at room temperature.

[0033] Fig. 6 is a side cross-sectional view of an optical system and a camera module having the same according to a second embodiment.

[0034] Fig. 7 is a table showing the aspherical coefficient of the aspherical lens surface among the lenses in the optical system of Fig. 6.

[0035] Fig. 8 is a table showing the Sag values ​​of the lens surfaces of the first to eighth lenses in the optical system of Fig. 6.

[0036] Figure 9 is a graph showing data on the diffraction MTF (Modulation Transfer Function) at low temperatures of the optical system of Figure 6.

[0037] Fig. 10 is a graph showing data on the diffraction MTF of the optical system of Fig. 6 at room temperature.

[0038] Figure 11 is a graph showing data on the diffraction MTF at high temperatures of the optical system of Figure 6.

[0039] Fig. 12 is a graph showing data on the aberration characteristics of the optical system of Fig. 6 at room temperature.

[0040] Fig. 13 is a side cross-sectional view of an optical system and a camera module having the same according to a third embodiment.

[0041] Fig. 14 is a table showing the aspherical coefficient of the aspherical lens surface among the lenses in the optical system of Fig. 13.

[0042] Fig. 15 is a table showing the Sag values ​​of the lens surfaces of the first to eighth lenses in the optical system of Fig. 13.

[0043] Figure 16 is a graph showing data on the diffraction MTF (Modulation Transfer Function) at low temperatures of the optical system of Figure 13.

[0044] Figure 17 is a graph showing data on the diffraction MTF of the optical system of Figure 13 at room temperature.

[0045] Figure 18 is a graph showing data on the diffraction MTF at high temperatures of the optical system of Figure 13.

[0046] Fig. 19 is a graph showing data on the aberration characteristics of the optical system of Fig. 13 at room temperature.

[0047] FIG. 20 is an example of a vehicle having an optical system according to an embodiment of the invention.

[0048] Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the attached drawings.

[0049] However, the technical idea of ​​the present invention is not limited to some of the embodiments described, but can be implemented in various different forms, and within the scope of the technical idea of ​​the present invention, one or more of the components between the embodiments can be selectively combined or substituted for use.

[0050] In addition, terms (including technical and scientific terms) used in this embodiment may be interpreted as having a meaning that can be generally understood by a person of ordinary skill in the technical field to which this embodiment belongs, unless explicitly and specifically defined and described, and terms that are commonly used, such as terms defined in a dictionary, may be interpreted in consideration of the contextual meaning of the relevant technology.

[0051] Additionally, the terms used in this embodiment are for the purpose of describing the embodiments and are not intended to limit the present invention.

[0052] In this specification, the singular may also include the plural unless specifically stated otherwise 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, C.

[0053] Additionally, in describing the components of this embodiment, terms such as first, second, A, B, (a), (b), etc. may be used. These terms are only intended to distinguish the components from other components, and are not intended to limit the nature, order, or sequence of the components.

[0054] And, when a component is described as being 'connected', 'coupled', or 'connected' to another component, it may include not only cases where the component is 'connected', 'coupled', or 'connected' directly to the other component, but also cases where the component is 'connected', 'coupled', or 'connected' by another component between the component and the other component.

[0055] Additionally, when 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 expressed as "above" or "below," the meaning may include not only the upward direction but also the downward direction based on one component.

[0056] In the description of the invention, the "object side" may mean a surface of the lens facing the object side with respect to the optical axis (OA), and the "sensor side" may mean a surface of the lens facing the imaging surface (image sensor) with respect to the optical axis. The "object side" may be the "object side," and the "sensor side" may be the "image side." A convex surface of a lens may mean a convex shape in the optical axis or the paraxial region, and a concave surface of a lens may mean a concave shape in the optical axis or the paraxial region. The radius of curvature, the center thickness, and the optical axis spacing between lenses described in the table for lens data may mean values ​​(unit: mm) in the optical axis. The vertical direction may mean a direction perpendicular to the optical axis, and the end of a lens or lens surface may mean the end of an effective area of ​​a lens through which incident light passes. The size of the effective diameter of the lens surface may have a measurement error of up to ±0.4 mm depending on the measurement method, etc. The above-mentioned near-axis region refers to a very narrow region near the optical axis, and is a region where the distance that a light ray falls from the optical axis (OA) is almost 0. Hereinafter, the meaning of the optical axis may include the center of each lens or a very narrow region near the optical axis.

[0057]

[0058] As shown in FIGS. 1, 6, and 13, the optical systems (1000, 1100, 1200) according to the first to third embodiments of the present invention may include seven or more lenses. The optical systems (1000, 1100, 1200) and the camera modules having the same may be mounted inside or outside a vehicle to monitor the driver or sense external objects or lanes. The material of the lenses may be selected from glass or plastic, and the coefficient of linear expansion of glass is lower than that of plastic. Accordingly, glass lenses are employed to suppress changes in the focal imaging position due to temperature changes. However, glass lenses are more expensive than plastic lenses, and there is a problem that it is difficult to meet the demand for low cost. Therefore, the lenses in the optical systems (1000, 1100, 1200) are required to have a mixed configuration of glass lenses and plastic lenses. By employing these plastic lenses, the optical system (1000, 1100, 1200) can be made lighter and cheaper by reducing the thickness of the plastic lenses, and the plastic lenses can provide excellent correction for various aberrations such as spherical aberration and chromatic aberration. In addition, since the plastic lenses can provide aspherical lenses, distortion in the peripheral areas can be minimized.

[0059] The optical system (1000, 1100, 1200) may include n lenses, where the n-th lens may be the last lens adjacent to the image sensor (400), and the (n-1)-th lens may be the lens closest to the last lens. n is an integer greater than or equal to 7, for example, 7 to 8. The n lenses may have a ratio of glass lenses to plastic lenses in the range of 2:5 to 3:5.

[0060] Within the optical system (1000, 1100, 1200), at least one lens closest to the object may be made of glass. One or more lenses, for example, one to three lenses, closest to the object may be made of glass. Since the rate of contraction and expansion of glass lenses due to temperature changes is smaller than that of plastic lenses, the glass lenses may be arranged in an area adjacent to the outside within the lens barrel.

[0061] At least one lens closest to the image sensor (400) within the optical system (1000, 1100, 1200) may be made of plastic. For example, at least one lens closest to the image sensor (400) may be made of plastic, and preferably, at least two lenses adjacent to the image sensor (400) may be made of plastic. That is, since the n-th and n-1-th lenses in the optical system (1000, 1100, 1200) are arranged as plastic lenses, various aberrations can be corrected for the light incident on the image sensor (400).

[0062] Within the optical system (1000, 1100, 1200), plastic lenses can be arranged in series, and glass lenses can be arranged in series. Within the optical system (1000, 1100, 1200), plastic lenses can be arranged between glass lenses. Within the optical system (1000, 1100, 1200), glass lenses can be arranged between plastic lenses.

[0063] The plurality of lenses arranged adjacent to the object side of the optical system (1000, 1100, 1200) may be sequentially arranged glass lenses, and the plurality of lenses arranged adjacent to the sensor side may be sequentially arranged plastic lenses. Specifically, the first to third lenses (101-103, 201-203, 301-301) may be made of glass, and the fourth to eighth lenses (104-108, 204-208, 304-308) may be made of plastic. In addition, the fourth lens (104, 204, 304) may be changed to a glass material and applied. Since the plastic material lens has a wide range of refractive indices, it is difficult to reduce chromatic aberration. Accordingly, the refractive index of the glass lens placed adjacent to the object side can be designed to have a high refractive index so that the chromatic aberration of the optical system (1000, 1100, 1200) is reduced.

[0064] In the optical system (1000, 1100, 1200), at least one of the lenses made of glass may have a biconvex shape, and the refractive index of the lens having the biconvex shape may be 1.4 to 1.6 or higher. In the first to third embodiments, both sides of the third lens (103, 203, 303) may have a convex shape, and the refractive index may satisfy 1.4 to 1.6. Through this, the glass lens arranged on the object side can effectively collect and input light to the plastic lens arranged on the sensor side.

[0065] By sequentially arranging lenses of the same material in the optical system (1000, 1100, 1200), an assembly structure in which the materials within the lens barrels are distinguished can be provided. For example, a single lens barrel having a partition wall protruding from the inner surface can have a glass lens assembled through one end of an opening, and a plastic lens assembled through the other end of an opening. Alternatively, a lens barrel that is double-injected with different materials can have a glass lens assembled in the direction of one end of an opening, and a plastic lens assembled through the other end of an opening. Alternatively, two lens barrels in which lenses of different materials are arranged can be assembled and joined through optical axis alignment. Alternatively, the lens barrel has an inner barrel arranged at a position spaced apart from the inner surface, and a glass lens can be assembled through one end of an opening, and a plastic lens can be assembled through the other end of an opening.

[0066] In other words, in a lens barrel having the above assembly structure, physical interference between a plastic lens, which undergoes shape change with temperature change, and a glass lens, which undergoes less shape change with temperature change, can be minimized, thereby minimizing changes in lens performance due to temperature change. Furthermore, the assembly process can be simplified by assembling lenses of the same material in the same direction.

[0067] Each lens (101-108, 201-208, 301-308) can have an object side surface and a sensor side surface. The optical system may have more lenses with aspherical sensor sides and aspherical object sides than the number of glass lenses. The optical system may have fewer lenses with spherical sensor sides and spherical object sides than lenses with aspherical surfaces on both sides. The optical system (1000, 1100, 1200) has more aspherical lenses than spherical lenses, so it can correct various aberrations.

[0068] Among the lenses of the optical system (1000, 1100, 1200), the lens with the highest refractive index can be positioned adjacent to the object. The highest refractive index can be 1.9 or higher. The chromatic dispersion of light incident on the lens with the highest refractive index can be increased, and the center thickness can be made thinner than the edge thickness. In addition, since the lens with the highest refractive index is positioned on the object side, the radius of curvature of the second and subsequent lenses can be easily changed, and the center thickness can be increased.

[0069]

[0070] The effective diameter may be the diameter of the effective area where effective light is incident on each lens. The effective diameter is the length in the direction (X, Y) orthogonal to the optical axis, and is the average of the effective diameter on the object side of each lens and the effective diameter on the sensor side. The "diameter of the lens surface" may mean the "effective diameter of the lens." The "diameter of the lens" may be the diameter of the entire lens including the flange portion of the lens in addition to the effective area of ​​the lens. Although the flanges of the lenses are not illustrated in FIGS. 1, 6, and 13, the flanges may be portions that protrude perpendicular to the optical axis from the side surfaces of the lenses so that the lenses are coupled to the barrel. The flanges may not receive effective light. A spacer may be additionally arranged between the flanges of different lenses so that the lenses are coupled to the barrel.

[0071] Each of the lenses (101-108, 201-208, 301-308) 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. In other words, the effective area may be defined as an effective area or effective diameter through which the incident light is refracted to implement optical characteristics. The ineffective area may be arranged around the periphery of the effective area. The ineffective area may be an area through which effective light is not incident from a plurality of lenses. In other words, the ineffective area may be an area unrelated to the optical characteristics. In addition, an end of the ineffective area may be an area fixed to a lens barrel or the like that accommodates the lens.

[0072]

[0073] Within the optical system (1000, 1100, 1200), the TTL (Total top length) may be more than 2.5 times, for example, more than 2.5 times and less than 3 times, than the Imgh. The TTL (Total track length) is the distance from the center of the object-side surface of the first lens to the top surface of the image sensor (400) on the optical axis (OA). Imgh is twice the distance from the optical axis (OA) to the diagonal end of the image sensor (400) or the maximum diagonal length. Within the optical system (1000, 1100, 1200), the effective focal length (EFL) is provided to be 6 mm or more and the field of view (FOV) is provided to be less than 120 degrees, so that the optical system can be provided as a standard optical system in a vehicle camera module. For example, the optical system and the camera module according to the embodiment can be applied to a camera for an ADAS (Advanced Driving Assistance System) installed inside or outside a vehicle.

[0074] The optical system (1000, 1100, 1200) may have a TTL / Imgh condition of 2 or more and 2.5 or more, for example, 2.5 or more and 3.0 or less. By setting the TTL / Imgh value to 2.5 or more and 3.0 or less in the optical system (1000, 1100, 1200), a vehicle lens optical system can be provided. Accordingly, the optical system (1000, 1100, 1200) can provide an image without exaggeration or distortion in the formed image.

[0075]

[0076] The effective diameter of at least one plastic lens within the optical system (1000, 1100, 1200) may be smaller than the length of the image sensor (400). The effective diameter is the diameter or length of the effective area into which light is incident. The length of the image sensor (400) is the maximum length of the diagonal in the direction orthogonal to the optical axis (OA). There may not be a number of lenses within the optical system (1000, 1100, 1200) having an effective diameter greater than the length of the image sensor (400).

[0077] The lens unit (100, 200, 300) may be a mixture of glass lenses and plastic lenses. The number of plastic lenses may be 60% or more of the total number of lenses, and may range from 40% to 85% or from 60% to 80%. Accordingly, when more plastic lenses are placed within the camera module, the weight of the camera module can be reduced, and the plastic material makes it easy to polish and process, resistant to external impacts, competitively priced, and easy to secure materials. In addition, various aberrations can be corrected by the plastic lenses, thereby preventing deterioration of optical performance.

[0078] An embodiment of the invention can reduce the weight of a camera module, provide a lower manufacturing cost, suppress deterioration of optical characteristics due to temperature change, and allow various types of plastic lenses to replace glass lenses by further mixing plastic lenses into the optical system (1000, 1100, 1200). In addition, the lens surface, such as an aspherical surface or a free-form surface, can be easily polished and processed.

[0079]

[0080] The lens unit (100, 200, 300) may include lenses of a first material and lenses of a second material arranged along the optical axis (OA). The first material may be glass, and the second material may be plastic. The lenses of the first material may be arranged between the lenses of the second material. The lenses of the second material may be arranged between the lenses of the first material.

[0081] The lens unit (100, 200, 300) may include lenses of a first material having a spherical surface along the optical axis (OA) and lenses of a second material having an aspherical surface. The first material may be a glass material, and the second material may be a plastic material. The lenses of the first material having a spherical surface may be arranged between the lenses of the second material having an aspherical surface. The lenses of the second material may be arranged between the lenses of the first material having an aspherical surface and the lenses of the first material having a spherical surface.

[0082]

[0083] The effective diameter of the lens closest to the object side within the lens unit (100, 200, 300) may be smaller than the effective diameter of the lens closest to the image sensor (400). Accordingly, the brightness of the optical system can be controlled. The effective diameter may be the average effective diameter of the object side and the sensor side of each lens. By controlling the effective diameter size of each lens, the optical system (1000, 1100, 1200) can control the incident light to compensate for the deterioration of optical characteristics due to resolution and temperature change, improve chromatic aberration control characteristics, and improve the vignetting characteristics of the optical system (1000, 1100, 1200).

[0084] The lens unit (100, 200, 300) may include first to eighth lenses (101-108, 201-208, 301-308) aligned from the object side toward the sensor side along the optical axis.

[0085]

[0086] Within the lens section (100, 200, 300), when the focal length is taken as an absolute value, the focal length of the lens closest to the object may be smaller than the focal length of the plastic lens.

[0087]

[0088] The lens unit (100, 200, 300) may be arranged in a camera module having an inner barrel on one side or the entire inner surface of a lens barrel. The lens unit (100, 200, 300) may be arranged in a camera module having a plurality of inner barrels around different lenses of the lens barrel. The lens unit (100, 200, 300) may be arranged in a camera module having a first inner barrel in contact with the outer surface of at least one lens of the lens barrel and a second inner barrel in contact with the outer surface of at least one lens. The lens unit (100, 200, 300) may be arranged in a camera module having a plurality of inner barrels each arranged between the outer surface of at least one or two or more lenses and the lens barrel. The lens unit (100, 200, 300) may be arranged in a camera module in which the plurality of inner barrels have a material different from the material of the lens barrel.

[0089] Among the lenses constituting the lens unit (100, 200, 300), at least some of the lenses made of glass may be placed in the lens barrel, and at least some of the lenses made of plastic may be placed in the inner barrel placed within the lens barrel. Through this, the optical system (1000, 1100, 1200) can maintain resolution according to temperature changes. The lens unit (100, 200, 300) may be placed in a camera module having different barrels to minimize decentering of lenses, such as plastic lenses, that expand according to temperature changes. The lens barrel in which the lens unit (100, 200, 300) is placed has a plurality of inner barrels within the lens barrel, thereby maintaining the resolution of the optical system according to temperature changes and suppressing deformation of the lenses. Therefore, the effective diameter of at least some of the glass lenses included in the lens unit (100, 200, 300) may be smaller than the effective diameter of at least some of the plastic lenses.

[0090]

[0091] The average effective diameter of the glass materials may be 5 mm or more, for example, in the range of 5 mm to 10 mm. The average effective diameter of the plastic material may be 5 mm or more, for example, in the range of 5 mm to 10 mm. The lens having the minimum effective diameter may be made of glass, and the lens having the maximum effective diameter may be made of plastic. The minimum effective diameter in the lens unit (100, 200, 300) may be in the range of 6 mm to 8 mm, and the maximum effective diameter may be in the range of 9 mm to 11 mm. In addition, the optical system (1000, 1100, 1200) may improve the resolution and chromatic aberration control characteristics by controlling the incident light, and may improve the vignetting characteristics of the optical system (1000, 1100, 1200).

[0092]

[0093] The optical system (1000, 1100, 1200) or camera module may include an image sensor (400). The image sensor (400) can detect light and convert it into an electrical signal. The image sensor (400) can detect light that has sequentially passed through the lens unit (100, 200, 300). The image sensor (400) may include an element capable of detecting incident light, such as a charge-coupled device (CCD) or a complementary metal oxide semiconductor (CMOS).

[0094] Here, the number of lenses having an effective diameter greater than the length of the image sensor (400) may be 0 to 2, and the number of lenses having an effective diameter less than the length of the image sensor (400) may be 7 to 8.

[0095]

[0096] The optical system (1000, 1100, 1200) or camera module may include a filter (500). The filter (500) may be positioned between the last lens and the image sensor (400). The filter (500) may be positioned between the lens closest to the sensor side among the lenses of the lens unit (100, 200, 300) and the image sensor (400). For example, the filter (500) may be positioned between the nth lens and the image sensor (400).

[0097] The cover glass is placed between the filter (500) and the image sensor (400), and protects the upper portion of the image sensor (400) and can prevent a decrease in the reliability of the image sensor (400). The cover glass can be removed. The cover glass may be a protective glass.

[0098] The filter (500) may include an infrared filter or an infrared cut-off filter (IR cut-off). The filter (500) may allow light of a set wavelength band to pass through and filter out light of a different wavelength band. When the filter (500) includes an infrared filter, it may block radiant heat emitted from external light from being transmitted to the image sensor (400). In addition, the filter (500) may transmit visible light and reflect infrared light.

[0099] The optical system (1000, 1100, 1200) according to the embodiment may include an aperture (Stop). The aperture may control the amount of light incident on the optical system (1000, 1100, 1200).

[0100] In the optical systems (1000, 1100, 1200) of the first to third embodiments, the sum of the refractive indices of the lenses of the lens units (100, 200, 300) may be 10 or more, for example, in the range of 10 to 15, and the average of the refractive indices may be 1.5 to 1.7. The sum of the Abbe numbers of each of the lenses may be 300 or more, for example, in the range of 350 to 400, and the average of the Abbe numbers may be 50 or less, for example, in the range of 40 to 50. The sum of the central thicknesses of the entire lens may be 15 mm or more, for example, in the range of 15 mm to 20 mm, and the average of the central thicknesses may be in the range of 2 mm to 3 mm. The sum of the central spacings between the lenses on the optical axis (OA) may be 5 mm or more, for example, in the range of 5 mm to 10 mm, and may be smaller than the sum of the central thicknesses of the lenses. Additionally, the average value of the effective diameter of each lens surface (S1-S16) of the lens unit (100, 200, 300) can be provided in the range of 5 mm or more, for example, 5 mm to 10 mm.

[0101]

[0102] In the optical system according to the first to third embodiments of the invention, the angle of view (diagonal) may be 120 degrees or less, for example, in the range of 100 degrees to 120 degrees. The F number of the optical system or the camera module may be 2.0 or less, for example, in the range of 1.5 to 2.0 or in the range of 1.6 to 1.8. The vehicle optical system may have a horizontal field of view (FOV_H) in the Y-axis direction that may be greater than 100 degrees and less than 120 degrees, for example, in the range of 100 degrees to 110 degrees. In addition, the vertical field of view may be provided at an angle smaller than the horizontal field of view. The horizontal field of view (FOV_H) is an angle of view based on the horizontal length of the sensor. Accordingly, it is possible to suppress a change in the focus imaging position due to temperature change, and provide a vehicle camera in which various aberrations are well corrected.

[0103] Because the optical systems used in vehicle cameras typically monitor road conditions, they can be designed based on the horizontal field of view, rather than the entire field of view. The optical system according to this embodiment is designed with a certain margin based on the inscribed circle of the image sensor. This ensures guaranteed optical performance within the range that satisfies the horizontal field of view (FOV_H).

[0104]

[0105] Since the embodiment is an optical system applied to a vehicle camera, the first lens (101, 201, 301) may be provided as a glass material, even though it is designed to use both a plastic lens and a glass lens. This is because glass has the advantage of being scratch-resistant and insensitive to external temperature compared to plastic. The first lens (101, 201, 301) may be a spherical lens made of glass.

[0106] In order to more effectively prevent scratches caused by foreign substances or by the interior of a vehicle, a glass lens may be used as the first lens (101, 201, 301), and the object-side surface of the first lens (101, 201, 301) may have a gently curved shape so as not to come into contact with external structures. This minimizes the occurrence of scratches due to contact with external structures. For driver monitoring, front / rear photography of the vehicle, lane detection, and detection of debris around the vehicle while the vehicle is being driven, the angle of view may be greater than 100 degrees and less than 120 degrees, for example, in the range of 100 degrees to 110 degrees. This horizontal angle of view may be a preset angle for an advanced driver assistance system (ADAS).

[0107] The optical system (1000, 1100, 1200) according to the embodiment may further include a reflective member for changing the path of light. The reflective member may be implemented as a prism that reflects incident light of the optical system (1000, 1100, 1200) toward the lenses. Hereinafter, the optical system according to the embodiment will be described in detail.

[0108]

[0109] An optical system according to a first embodiment of the invention will be described.

[0110] FIG. 1 is a side cross-sectional view of an optical system according to a first embodiment and a camera module having the same, FIG. 2 is a table showing aspherical coefficients of aspherical lens surfaces among lenses in the optical system of FIG. 1, FIG. 3 is a table showing Sag values ​​of lens surfaces of the first to eighth lenses in the optical system of FIG. 1, FIG. 4 is a graph showing data on diffraction MTF (Modulation Transfer Function) at room temperature of the optical system of FIG. 1, and FIG. 5 is a graph showing data on aberration characteristics at room temperature of the optical system of FIG. 1.

[0111] Referring to FIG. 1, the optical system (1000) includes a lens unit, and the lens unit may include a first lens (101) to an eighth lens (108). The first to eighth lenses (101 to 108) may be sequentially arranged along the optical axis (OA) of the optical system (1000). Light corresponding to information about an object may pass through the first lens (101) to the eighth lens (108) and a filter (500) and be incident on the image sensor (400).

[0112] The first lens (101) may be arranged closest to the object side. The first lens (101) may be arranged farthest from the sensor side. The first lens (101) may have negative (-) refractive power on the optical axis (OA). The first lens (101) may include a plastic material or a glass material, and may be made of glass, for example. The first lens (101) made of glass can reduce changes in the center position and radius of curvature due to temperature changes in the surrounding environment, and can protect the incident side surface of the optical system (1000).

[0113] The first surface (S1) on the object side of the first lens (101) with respect to the optical axis may be convex, and the second surface (S2) on the sensor side may be concave. The first lens (101) may have a convex meniscus shape toward the object side. The first lens (101) may have a concave meniscus shape toward the sensor side. The first lens (101) is made of glass and may have a spherical surface.

[0114] The refractive index (n1) of the first lens (101) can satisfy the condition of n1>1.6 or n1>1.7. When the refractive index (n1) of the first lens (101) satisfies the condition, the radius of curvature of the first and second lenses (101, 102) can be increased, and lens manufacturing can be facilitated. When the refractive index (n1) of the first lens (101) is smaller than the condition, the lens surface must be formed to be sharply concave or convex in order to increase the refractive power of the first and second lenses (101, 102), in which case lens manufacturing is not easy, the lens defect rate increases, and it may cause a decrease in yield. At least one or both of the first surface (S1) and the second surface (S2) can be provided without a critical point from the optical axis (OA) to the end of the effective area.

[0115]

[0116] The second lens (102) may be arranged second from the object side. The second lens (102) may be arranged seventh from the sensor side. The second lens (102) may be arranged between the first lens (101) and the third lens (103). The second lens (102) may have positive (+) refractive power in the optical axis (OA). The second lens (102) may include a plastic or glass material. For example, the second lens (102) may be provided as a glass material.

[0117] The third surface (S3) on the object side of the second lens (102) may be concave with respect to the optical axis (OA), and the fourth surface (S4) on the sensor side may be convex. The second lens (102) may have a meniscus shape that is convex toward the sensor side. The second lens (102) may have a meniscus shape that is concave toward the object side. The second lens (102) is made of glass and may have a spherical surface. At least one or both of the third surface (S3) and the fourth surface (S4) may be spherical. At least one or both of the third surface (S3) and the fourth surface (S4) may be provided without a critical point from the optical axis (OA) to the end of the effective area.

[0118] The aperture (Stop) may be arranged around the sensor-side fourth surface (S4) of the second lens (102). The aperture (Stop) may be arranged around the object-side fifth surface (S5) of the third lens (103). The aperture can reduce the TTL within the field of view range, and the optical system can be miniaturized. Accordingly, the yield by weight of the optical system can be prevented from decreasing, and production efficiency can be improved. In addition, the optical system can be miniaturized by reducing the TTL within the horizontal field of view (FOV_H) of 100 to 120 degrees.

[0119]

[0120] The third lens (103) may be arranged third from the object side. The third lens (103) may be arranged sixth from the sensor side. The third lens (103) may be arranged between the second lens (102) and the fourth lens (104). The third lens (103) may have positive (+) refractive power on the optical axis (OA). The third lens (103) may include a plastic or glass material. For example, the third lens (103) may be provided as a glass material.

[0121] The object-side fifth surface (S5) of the third lens (103) may be convex with respect to the optical axis, and the sensor-side sixth surface (S6) may be convex. The third lens (103) may have a convex shape on both sides. The third lens (103) may be made of glass and may be spherical. At least one or both of the fifth surface (S5) and the sixth surface (S6) may be spherical. At least one or both of the fifth surface (S5) and the sixth surface (S6) may be provided without a critical point from the optical axis (OA) to the end of the effective area.

[0122]

[0123] The fourth lens (104) may be arranged as the fourth lens from the object side. The fourth lens (104) may be arranged as the fifth lens from the sensor side. The fourth lens (104) may be arranged between the third lens (103) and the fifth lens (105). The fourth lens (104) may have negative (-) refractive power on the optical axis (OA). The fourth lens (104) may include a plastic or glass material. For example, the fourth lens (104) may be provided as a plastic material.

[0124] The object-side seventh surface (S7) of the fourth lens (104) with respect to the optical axis may be concave, and the sensor-side eighth surface (S8) may be concave. The fourth lens (104) may have a concave shape on both sides. The fourth lens (104) may be made of a plastic material and may be aspherical. At least one or both of the seventh surface (S7) and the eighth surface (S8) may be aspherical. At least one or both of the seventh surface (S7) and the eighth surface (S8) may be provided without a critical point from the optical axis (OA) to the end of the effective area.

[0125]

[0126] The fifth lens (105) may be arranged as the fifth lens from the object side. The fifth lens (105) may be arranged as the fourth lens from the sensor side. The fifth lens (105) may be arranged between the fourth lens (104) and the sixth lens (106). The fifth lens (105) may have positive (+) refractive power on the optical axis (OA). The fifth lens (105) may include a plastic or glass material. For example, the fifth lens (105) may be provided as a plastic material.

[0127] The ninth surface (S9) on the object side of the fifth lens (105) with respect to the optical axis may be convex, and the tenth surface (S10) on the sensor side may be convex. The fifth lens (105) may have a shape in which both sides are convex. The fifth lens (105) may be made of a plastic material and may be aspherical. At least one or both of the ninth surface (S9) and the tenth surface (S10) may be aspherical. At least one or both of the ninth surface (S9) and the tenth surface (S10) may be provided without a critical point from the optical axis (OA) to the end of the effective area.

[0128]

[0129] The sixth lens (106) may be arranged as the sixth lens from the object side. The sixth lens (106) may be arranged as the third lens from the sensor side. The sixth lens (106) may be arranged between the fifth lens (105) and the seventh lens (107). The sixth lens (106) may have positive refractive power on the optical axis (OA). The sixth lens (106) may include a plastic or glass material. For example, the sixth lens (106) may be provided as a plastic material.

[0130] The object-side eleventh surface (S11) of the sixth lens (106) with respect to the optical axis may be convex, and the sensor-side twelfth surface (S12) may be convex. The sixth lens (106) may have a convex shape on both sides. The sixth lens (106) may be made of a plastic material and may be aspherical. At least one or both of the eleventh surface (S11) and the twelfth surface (S12) may be aspherical. At least one or both of the eleventh surface (S11) and the twelfth surface (S12) may be provided without a critical point from the optical axis (OA) to the end of the effective area.

[0131]

[0132] The seventh lens (107) may be arranged as the seventh lens from the object side. The seventh lens (107) may be arranged as the second lens from the sensor side. The seventh lens (107) may be arranged between the sixth lens (106) and the eighth lens (108). The seventh lens (107) may have negative (-) refractive power on the optical axis (OA). The seventh lens (107) may include a plastic or glass material. For example, the seventh lens (107) may be provided as a plastic material.

[0133] The object-side 13th surface (S13) of the seventh lens (107) may be convex with respect to the optical axis, and the sensor-side 14th surface (S14) may be concave. The object-side 13th surface (S13) of the seventh lens (107) may be convex with respect to the optical axis, and the sensor-side 14th surface (S14) may be concave. The seventh lens (107) may have a concave meniscus shape on the sensor side. The seventh lens (107) may have a convex meniscus shape on the object side. The seventh lens (107) may be made of a plastic material and may be aspherical. At least one or both of the 13th surface (S13) and the 14th surface (S14) may be aspherical.

[0134] The thirteenth surface (S13) of the seventh lens (107) may have a critical point from the optical axis to the end of the effective area. When the thirteenth surface (S13) has a critical point, it may be located in a range of 30% to 50%, preferably 40% to 45%, of the effective radius from the optical axis. The critical point of the thirteenth surface (S13) may be located in a range of 1.5 mm to 2.5 mm, preferably 1.8 mm to 2.3 mm from the optical axis. The critical point of the thirteenth surface (S13) may be a point where the sign of the gradient value with respect to the optical axis and the direction perpendicular to the optical axis changes from positive (+) to negative (-) or from negative (-) to positive (+), and may mean a point where the gradient value is 0. In addition, the critical point of the thirteenth surface (S13) may be a point where the gradient value of a tangent passing through the lens surface increases and then decreases, or a point where the gradient value decreases and then increases. The 14th surface (S14) of the 7th lens (107) can be provided without a critical point from the optical axis to the end of the effective area.

[0135]

[0136] The eighth lens (108) may be arranged as the eighth lens from the object side. The eighth lens (108) may be arranged closest to the sensor side. The eighth lens (108) may have positive refractive power on the optical axis (OA). The eighth lens (108) may include a plastic or glass material. For example, the eighth lens (108) may be provided as a plastic material.

[0137] The object-side 15th surface (S15) of the eighth lens (108) with respect to the optical axis may be convex, and the sensor-side 16th surface (S16) may be concave. The eighth lens (108) may have a concave meniscus shape on the sensor side. The eighth lens (108) may have a convex meniscus shape on the object side. The eighth lens (108) may be made of a plastic material and may be aspherical. At least one or both of the 15th surface (S15) and the 16th surface (S16) may be aspherical. The 15th surface (S15) of the eighth lens (108) may be provided without a critical point from the optical axis to the end of the effective area.

[0138] The sixteenth surface (S16) of the eighth lens (108) may have a critical point from the optical axis to the end of the effective area. When the sixteenth surface (S16) has a critical point, it may be located in a range of 80% to 95%, preferably 85% to 90%, of the effective radius from the optical axis. The critical point of the sixteenth surface (S16) may be located in a range of 3.5 mm to 5.0 mm, preferably 4.0 mm to 4.5 mm from the optical axis. The critical point of the sixteenth surface (S16) may be a point where the sign of the gradient value with respect to the optical axis and the direction perpendicular to the optical axis changes from positive (+) to negative (-) or from negative (-) to positive (+), and may mean a point where the gradient value is 0. In addition, the critical point of the sixteenth surface (S16) may be a point where the gradient value of a tangent passing through the lens surface increases and then decreases, or a point where the gradient value decreases and then increases.

[0139]

[0140] LensSurfaceRadiusThicknessndvdSemiApertureFocal length1S1100.0000.8001.72954.6745.021-6.500 S24.5293.204 3.654 2S1-104.8653.0001.92320.8803.52322.500 S2-17.7370.586 3.426 3S110.3283.5931.43795.1003.81510.351 S2(STOP)-7.2280.918 3.871 4S1-8.4831.0001.61425.5853.530-11.097 S238.0170.875 3.600 5S118.3232.8611.53655.9814.45717.638 S2-18.6630.200 4.789 6S18.8952.8261.53655.9814.89512.925 S2-28.5100.596 4.863 7S119.6971.2001.61425.5854.698-14.934 S26.1511.054 4.731 8S15.7812.4861.53655.9814.88932.267 S27.3561.024 5.066 FilterS1Infinity0.900 5.075 S2Infinity2.509 5.087 ImageImageInfinity-0.009 5.161

[0141] Table 1 shows the surface number (Surface), radius of curvature (Radius), center thickness of each lens or distance between lens surfaces (Thickness), refractive index (Index,nd), Abbe number (Abbe,vd), effective radius (Semi Aperture), and focal length (Fcoal length) of the lens according to the first embodiment of the present invention. At this time, the unit of the radius of curvature and thickness or distance may be mm.

[0142] Item ValueItem ValueF6.210ET12.528ΣIndex12.927ET22.725ΣAbbe389.766ET31.739ΣCT17.767ET41.997ΣCG7.433ET51.121CA_max10.042ET61.185CA_min6.851ET72.51 0CA_Aver8.410ET82.167CT_max3.593F-number1.650CT_min0.800HFOV102.000CT_Aver2.221ImgH10.322EPD3.764SD19.220BFL4.424TTL29.62356TD26.224

[0143] Table 2 shows the items of the mathematical formulas described above in the optical system (1000) of the embodiment, including the total track length (TTL) (mm), back focal length (BFL), effective focal length (F) (mm), ImgH (mm), effective diameter (CA) (mm), thickness (mm), TTL (mm), the optical axis distance from the first surface (S1) to the eighth surface (S8) TD (mm), the optical axis distance from the stop (Stop) to the eighth surface (S8) SD (mm), the sum of refractive indices, the sum of Abbe numbers, the sum of thicknesses (mm), the sum of spacings between adjacent lenses, effective diameter characteristics, horizontal field of view (HFOV) (Degree), edge thickness (ET), F number, etc. of the optical system (1000).

[0144] The center thicknesses of the first to eighth lenses (101 to 108) are represented by CT1 to CT8, the edge thicknesses at the ends of the effective areas of each lens are represented by ET1 to ET8, the center gap between two adjacent lenses is represented by CG1 to CG7, and the edge gaps between the edges of each lens are represented by EG1 to EG8. The BFL (Back focal length) is the optical axis distance from the image sensor (400) to the center of the last lens. The TTL is the optical axis distance from the center of the first surface (S1) of the first lens (101) to the upper surface of the image sensor (400).

[0145] As shown in Fig. 2, among the lenses of the lens unit in the first embodiment, the lens surfaces of the fourth to eighth lenses (104 to 108) may include aspherical surfaces having a 30th aspherical coefficient. For example, the fourth to eighth lenses (104 to 108) may include lens surfaces having a 30th aspherical coefficient. As described above, since the aspherical surface having a 30th aspherical coefficient (a value other than "0") can significantly change the aspherical shape of the periphery, the optical performance of the periphery of the field of view (FOV) can be well corrected.

[0146] When comparing the absolute values ​​of the curvature radii of each lens, the curvature radii of the third surface (S3) of the second lens (102) on the optical axis (OA) may be the largest among the lenses, and the curvature radii of the second surface (S2) of the first lens (101) may be the smallest among the lenses. The difference between the maximum curvature radii and the minimum curvature radii may be 15 times or more, for example, 20 to 25 times. The curvature radii of the sensor-side surface of the first lens (101) arranged on the object side of the second lens (102) may be the smallest among the lenses.

[0147] In temperature-compensated designs that require maintaining resolution across temperatures ranging from -40 to 100 degrees Celsius, a larger radius of curvature can be advantageous. Aluminum lens barrels can be used for temperature compensation. Aluminum barrels have large manufacturing tolerances, which can significantly misalign the optical axes of individual lenses during assembly. Therefore, a larger radius of curvature can be used to reduce sensitivity to manufacturing tolerances.

[0148] The fourth to eighth lenses (104 to 108) having aspherical shapes can be designed to have gentle shapes. If the aspherical surface is positioned at the frontmost position in the optical system (1000), the performance of the lens is improved, but the assemblability may be reduced. To improve the assemblability, the shapes of the fourth to eighth lenses (104 to 108) must be designed to have gentle shapes. In order to minimize the influence on the lens placed on the sensor side when assembling the lens in the barrel, the lens can be designed to have almost no curvature.

[0149] Both the object-side and sensor-side surfaces of the seventh lens (107) and the eighth lens (108) may include inflection points and may have a gull-shaped shape (a shape including both concave and convex shapes). Accordingly, when a lens positioned adjacent to the image sensor (400) has an inflection point, the performance of aberrations relative to the axis (e.g., distortion aberration, coma aberration in the peripheral field, etc.) may be improved.

[0150] The second lens (102) may have a concave meniscus shape toward the sensor side, and the third lens (103) may have a biconvex shape. Since the second lens (102) has a meniscus shape, the effective diameter of the first lens (101) is reduced, and since the third lens (103) has a biconvex shape made of glass, temperature compensation is easy and aberration correction is effective. In order to correct aberration and form an appropriate focal length, the lens arranged adjacent to the aperture (STOP) may have a biconvex shape. For example, the third lens arranged on the sensor side of the aperture (STOP) may have a biconvex shape.

[0151] The absolute value of the curvature radius of the first surface (S1) of the first lens (101) may be greater than the absolute value of the curvature radius of the second surface (S2). The absolute value of the curvature radius of the third surface (S3) of the second lens (102) may be greater than the absolute value of the curvature radius of the fourth surface (S4). The absolute value of the curvature radius of the fifth surface (S5) of the third lens (103) may be greater than the absolute value of the curvature radius of the sixth surface (S6). The absolute value of the curvature radius of the seventh surface (S7) of the fourth lens (104) may be less than the absolute value of the curvature radius of the eighth surface (S8). The absolute value of the curvature radius of the ninth surface (S9) of the fifth lens (105) may be less than the absolute value of the curvature radius of the tenth surface (S10). The absolute value of the curvature radius of the eleventh surface (S11) of the sixth lens (106) may be smaller than the absolute value of the curvature radius of the twelfth surface (S12). The absolute value of the curvature radius of the thirteenth surface (S13) of the seventh lens (107) may be larger than the absolute value of the curvature radius of the fourteenth surface (S14). The absolute value of the curvature radius of the fifteenth surface (S15) of the eighth lens (108) may be smaller than the absolute value of the curvature radius of the sixteenth surface (S16).

[0152] When the curvature radius of the object-side surface and the sensor-side surface of the first lens (101) satisfy condition 1 below, the absolute value of the curvature radius on the optical axis of the object-side surface of the first lens (101) is formed into a shape of 60 or more (close to a plane), so that the refractive power of the first lens (101) can be designed to be large, and the curvature radius on the optical axis of the sensor-side surface of the first lens (101) is designed to be small, so that an appropriate angle of view can be set for the optical system.

[0153] The absolute value of the curvature radius of the object-side surface of the second lens (102) can satisfy a range of 60 to 110. Through this, damage to the entire optical system can be prevented by applying a UV coating to the object-side surface of the second lens (102).

[0154] The ratio of the radius of curvature of each lens can satisfy the following conditions.

[0155] Condition 1: 20 < |L1R1 / L1R2| < 25

[0156] Condition 2: 5 < |L2R1 / L2R2| < 10

[0157] Condition 3: 1 < |L3R1 / L3R2| < 1.5

[0158] Condition 4: 0.1 < |L4R1 / L4R2| < 0.5

[0159] Condition 5: 0.5 < |L5R1 / L5R2| < 1

[0160] Condition 6: 0.1 < |L6R1 / L6R2| < 0.5

[0161] Condition 7: 3 < |L7R1 / L7R2| < 5

[0162] Condition 8: 0.5 < |L8R1 / L8R2| < 1

[0163]

[0164] When describing the central thickness of the lenses based on the optical axis, the central thickness (CT3) of the third lens (103) is the largest among the lenses, and the central thickness (CT1) of the first lens (101) is the smallest among the lenses. The difference between the maximum and minimum central thicknesses among the lenses may be in the range of 2 mm or more and 3 mm or less.

[0165] The central thickness of each lens may satisfy any one of the following conditions:

[0166] Condition 1: CT2, CT3, CT4, CT5, CT6, CT7, CT8 > CT1

[0167] Condition 2: CT3 > CT2 > CT1, CT4, CT5, CT6, CT7, CT8

[0168] Condition 3: CT3 > CT1, CT2, CT4, CT5, CT6, CT7, CT8

[0169] Condition 4: CT2, CT3, CT5, CT6, CT7, CT8 > CT4 > CT1

[0170] Condition 5: CT2, CT3 > CT5 > CT1, CT4, CT6, CT7, CT8

[0171] Condition 6: CT2, CT3, CT5 > CT6 > CT1, CT4, CT7, CT8

[0172] Condition 7: CT2, CT3, CT5, CT6, CT8 > CT7 > CT1, CT4

[0173] Condition 8: CT2, CT3, CT5, CT6 > CT8 > CT1, CT4, CT7

[0174]

[0175] When describing the center spacing (CG) between the lenses, the center spacing (CG1) between the first lens (101) and the second lens (102) may be the maximum, and the center spacing (CG5) between the fifth and sixth lenses (105, 106) may be the minimum. The difference between the maximum center spacing and the minimum center spacing among the spaced lens spacings may be 2.5 mm or more, for example, in the range of 2.8 mm to 3.2 mm.

[0176] The center spacing between each lens can satisfy the conditions below.

[0177] Condition 1: CG1 > CG2, CG3, CG4, CG5, CG6, CG7

[0178] Condition 2: CG1, CG3, CG4, CG6, CG7 > CG2 > CG5

[0179] Condition 3: CG1, CG7 > CG3 > CG2, CG4, CG5, CG6

[0180] Condition 4: CG1, CG3, CG7 > CG4 > CG2, CG5, CG6

[0181] Condition 5: CG1, CG2, CG3, CG4, CG6, CG7 > CG5

[0182] Condition 6: CG1, CG3, CG4, CG7 > CG6 > CG2, CG5

[0183] Condition 7: CG1 > CG7 > CG2, CG3, CG4, CG5, CG6

[0184]

[0185] Regarding the effective diameter, the effective diameter of the 8th lens (108) closest to the sensor side is the maximum, and the lens with the maximum effective diameter may be a plastic lens. The lens with the maximum effective diameter may be the 8th lens (108). Here, the effective diameter is the average of the effective diameters of the object-side surface and the sensor-side surface of each lens. The lens surface with the maximum effective diameter may be the 16th surface (S16) of the 8th lens (108).

[0186] The lens having the minimum effective diameter may be any one of the glass material lenses, and for example, the effective diameter of the second lens (102) may be the minimum within the lens unit. The lens surface having the minimum effective diameter may be the fourth surface (S4) of the second lens (102).

[0187] The effective diameter may decrease from the first lens (101) to the second lens (102) and may increase from the fourth lens (104) to the fifth lens (105). Here, the effective diameter of each lens may mean the average of the effective diameter values ​​of the object-side surface of the lens and the effective diameter values ​​of the sensor-side surface of the lens. The average effective diameter values ​​of the object-side and sensor-side surfaces of each lens may decrease from the first lens (101) to the second lens (102) and may increase from the fourth lens (104) to the fifth lens (105). The position of the aperture (STOP) having a small effective diameter is arranged on the sensor side of the second lens (102), and the position of the aperture (STOP) is relatively closer to the object side than to the sensor side, so that the effective diameter of the first lens (101) may decrease.

[0188] The average effective diameter of the object-side and sensor-side surfaces of each glass lens positioned closer to the object than the plastic lens may be smaller than the average effective diameter of the object-side and sensor-side surfaces of each plastic lens. Alternatively, the effective diameter of the glass lens positioned on the object-side of the plastic lens may have the smallest effective diameter in the optical system (1000). For example, when the fourth to eighth lenses (104 to 108) are made of plastic and the third lens (103) is made of glass, the average effective diameter of the object-side and sensor-side surfaces of the third lens (103) may be smaller than the average of the effective diameters of the object-side and sensor-side surfaces of the fourth to eighth lenses (104 to 108). In addition, the average effective diameter of the object-side and sensor-side surfaces of the third lens (103) may have the smallest effective diameter in the optical system (1000). Among the first to eighth lenses (101-108), a plurality of lenses sequentially arranged may be made of glass, and the remaining lenses sequentially arranged may be made of plastic. Among the first to eighth lenses (101-108), the effective diameter of the glass lens arranged most adjacent to the lens made of plastic may be the smallest.

[0189] In relation to the above, an inner barrel may be additionally positioned between the plastic lens and the glass lens to minimize changes in optical performance due to changes in the shape of the plastic lens that expands at high temperatures. Alternatively, a partition wall protruding into the lens barrel may be formed between the plastic lens and the glass lens to prevent interference due to the high-temperature expansion of the plastic lens.

[0190] The effective diameter of each lens can satisfy any one of the conditions below.

[0191] Condition 1: CA_L5, CA_L6, CA_L7, CA_L8 > CA_L1 > CA_L2, CA_L3, CA_L4

[0192] Condition 2: CA_L1, CA_L3, CA_L4, CA_L5, CA_L6, CA_L7, CA_L8 > CA_L2

[0193] Condition 3: CA_L1, CA_L5, CA_L6, CA_L7, CA_L8 > CA_L3 > CA_L2, CA_L4

[0194] Condition 4: CA_L1, CA_L3, CA_L5, CA_L6, CA_L7, CA_L8 > CA_L4 > CA_L2

[0195] Condition 5: CA_L6, CA_L7, CA_L8 > CA_L5 > CA_L1, CA_L2, CA_L3, CA_L4

[0196] Condition 6: CA_L8 > CA_L6 > CA_L1, CA_L2, CA_L3, CA_L4, CA_L5, CA_L7

[0197] Condition 7: CA_L6, CA_L8 > CA_L7 > CA_L1, CA_L2, CA_L3, CA_L4, CA_L5

[0198] Condition 8: CA_L8 > CA_L1, CA_L2, CA_L3, CA_L4, CA_L5, CA_L6, CA_L7

[0199]

[0200] Regarding the refractive index, the refractive index of the second lens (102) may be the highest among the lenses and may be greater than 1.8, for example, greater than 1.9. The third lens (103) may have the lowest refractive index among the lenses. For example, the refractive index of the third lens (103) may be the lowest among the lenses and may be less than 1.5, for example, less than 1.45. The difference between the maximum refractive index and the minimum refractive index may be 0.4 or more.

[0201] The refractive index of each lens can satisfy any of the conditions below.

[0202] Condition 1: n2 > n1 > n3, n4, n5, n6, n7, n8

[0203] Condition 2: n2 > n1, n3, n4, n5, n6, n7, n8

[0204] Condition 3: n1, n2, n4, n5, n6, n7, n8 > n3

[0205] Condition 4: n1, n2 > n4 = n7 > n3, n5, n6, n8

[0206] Condition 5: n1, n2, n4, n7 > n5 = n6 = n8 > n3

[0207]

[0208] Comparing the Abbe numbers, the Abbe number of the third lens (103) is the largest among the lenses and may be 90 or greater. The Abbe number of the second lens (102) is the smallest among the lenses and may be 25 or less. The difference between the maximum Abbe number and the minimum Abbe number may be 70 or greater.

[0209] The Abbe number of each lens can satisfy any of the conditions below.

[0210] Condition 1: v3, v5, v6, v8 > v1 > v2, v4, v7

[0211] Condition 2: v1, v3, v4, v5, v6, v7, v8 > v2

[0212] Condition 3: v3 > v1, v2, v4, v5, v6, v7, v8

[0213] Condition 4: v1, v3, v5, v6, v8 > v4 = v7 > v2

[0214] Condition 5: v3 > v5 = v6 = v8 > v1, v2, v4, v7

[0215]

[0216] The focal lengths (F2, F3, F5, F6, F8) of the second, third, fifth, sixth, and eighth lenses (102, 103, 105, 106, and 108) may have positive (+) signs. The second, third, fifth, sixth, and eighth lenses (102, 103, 105, 106, and 108) may have positive (+) refractive power. The focal lengths (F1, F4, and F7) of the first, fourth, and seventh lenses (101, 104, and 107) may have negative (-) signs. The first, fourth, and seventh lenses (101, 104, and 107) may have negative (-) refractive power. A fourth lens (104) having negative (-) refractive power may be arranged on the sensor side of the third lens (103) having positive (+) refractive power. Through this, light incident from the object side can gather in the direction of the optical axis and then move away from the direction of the optical axis, thereby forming a stable optical path.

[0217]

[0218] When comparing the focal lengths in absolute values, the focal length of the eighth lens (108) is the largest among the lenses, and may be 20 or more and 50 or less. Among the lenses, the eighth lens (108) made of plastic may have the largest focal length and the smallest refractive power. The focal length of the first lens (101) is the smallest among the lenses, and the absolute value of the focal length of the first lens (101) may be 5 or more and 10 or less. Among the lenses, the first lens (101) made of glass may have the smallest focal length and the largest refractive power.

[0219] Among the lenses, the lens having the minimum focal length may be the first lens (101). The difference between the maximum focal length and the minimum focal length may be 10 or more or 20 or more. Accordingly, the optical system may have improved MTF characteristics, aberration control characteristics, resolution characteristics, etc. in the set field of view range, and may have good optical performance in the periphery of the field of view.

[0220] The absolute value of the focal length of each lens can satisfy any of the conditions below.

[0221] Condition 1: |f2|, |f3|, |f4|, |f5|, |f6|, |f7|, |f8| > |f1|

[0222] Condition 2: |f8| > |f2| > |f1|, |f3|, |f4|, |f5|, |f6|, |f7|

[0223] Condition 3: |f2|, |f4|, |f5|, |f6|, |f7|, |f8| > |f3| > |f1|

[0224] Condition 4: |f2|, |f5|, |f6|, |f7|, |f8| > |f4| > |f1|, |f3|

[0225] Condition 5: |f2|, |f8| > |f5| > |f1|, |f3|, |f4|, |f6|, |f7|

[0226] Condition 6: |f2|, |f5|, |f7|, |f8| > |f6| > |f1|, |f3|, |f4|

[0227] Condition 7: |f2|, |f5|, |f8| > |f7| > |f1|, |f3|, |f4|, |f6|

[0228] Condition 8: |f8| > |f1|, |f2|, |f3|, |f4|, |f5|, |f6|, |f7|

[0229]

[0230] The thickness (T1) of the first lens (101) may be maximum at the edge and minimum at the center, and the maximum thickness is in the range of 3 to 3.5 times the minimum thickness. The thickness (T2) of the second lens (102) may be minimum at the edge and maximum at the center, and the maximum thickness is in the range of 1 to 1.5 times the minimum thickness. The thickness (T3) of the third lens (103) may be maximum at the center and minimum at the edge, and the maximum thickness is in the range of 2 to 2.5 times the minimum thickness. The thickness (T4) of the fourth lens (104) may be minimum at the center and maximum at the edge, and the maximum thickness is in the range of 1.5 to 2 times the minimum thickness. The thickness (T5) of the fifth lens (105) may be maximum at the center and minimum at the edge, and the maximum thickness is in the range of 2.5 to 3 times the minimum thickness. The thickness (T6) of the sixth lens (106) may be maximum at the center and minimum at the edge, and the maximum thickness is in the range of 2 to 2.5 times the minimum thickness. The thickness (T7) of the seventh lens (107) may be minimum at the center and maximum at the edge, and the maximum thickness is in the range of 2 to 2.5 times the minimum thickness. The thickness (T8) of the eighth lens (108) may be maximum at the center and minimum at the edge, and the maximum thickness is in the range of 1 to 1.5 times the minimum thickness.

[0231] The thickness of each lens can satisfy any of the conditions below.

[0232] Condition 1: 0.1 < CT1 / ET1 < 0.5, 3 < ET1 / CT1 < 3.5

[0233]

[0234] Condition 2: 1 < CT2 / ET2 < 1.5, 0.5 < ET2 / CT2 < 1

[0235] Condition 3: 2 < CT3 / ET3 < 2.5, 0.1 < ET3 / CT3 < 0.5

[0236] Condition 4: 0.5 < CT4 / ET4 < 1, 1.5 < ET4 / CT4 < 2

[0237] Condition 5: 2.5 < CT5 / ET5 < 3, 0.1 < ET5 / CT5 < 0.5

[0238] Condition 6: 2 < CT6 / ET6 < 2.5, 0.1 < ET6 / CT6 < 0.5

[0239] Condition 7: 0.1 < CT7 / ET7 < 0.5, 2 < ET7 / CT7 < 2.5

[0240] Condition 8: 1 < CT8 / ET8 < 1.5, 0.5 < ET8 / CT8 < 1

[0241] Condition 9: 1 < ΣCT / ΣET < 1.5, 0.5 < ΣET / ΣCT < 1

[0242] Among the gaps (G1-G7) between the lenses, the first gap (G1) between the first and second lenses (101, 102) may have a maximum in the center and a minimum in the edge. The second gap (G2) between the second and third lenses (102, 103) may have a minimum in the center and a maximum in the edge. The third gap (G3) between the third and fourth lenses (103, 104) may have a maximum in the edge and a minimum in the center. The fourth gap (G4) between the fourth and fifth lenses (104, 105) may have a maximum in the edge and a minimum in the center. The fifth gap (G5) between the fifth and sixth lenses (105, 106) may have a maximum in the edge and a minimum in the center. The sixth gap (G6) between the sixth and seventh lenses (106, 107) may have a maximum in the edge and a minimum in the center. The seventh gap (G7) between the seventh and eighth lenses (107, 108) may be maximum at the edge and minimum at the center.

[0243]

[0244] Fig. 4 is a graph showing the diffraction MTF (Modulation Transfer Function) at room temperature in the optical system of Fig. 1, and is a graph showing the modulation ratio according to the spatial frequency. As shown in Fig. 4, in the first embodiment of the invention, the deviation of the MTF at low or high temperature based on room temperature may be less than 10%, that is, 7% or less.

[0245] Fig. 5 is a graph showing the aberration characteristics at room temperature in the optical system of Fig. 1. In the aberration graph of Fig. 5, spherical aberration (longitudinal spherical aberration), astigmatic field curves, and distortion are measured from left to right. In Fig. 5, 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. In addition, the graph for spherical aberration is a graph for light in wavelength bands of about 435 nm, about 486 nm, about 546 nm, about 587 nm, and about 656 nm, and the graphs for astigmatism and distortion are graphs for light in wavelength bands of about 546 nm. In the aberration diagram of Fig. 5, the closer each curve at room temperature is to the Y-axis, the better the aberration correction function can be interpreted. It can be seen that the optical system (1000) according to the first embodiment has measured values ​​close to the Y-axis in almost all areas. That is, the optical system (1000) according to the first embodiment 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. Here, the room temperature can be in the range of 22 degrees ± 5 degrees or in the range of 18 degrees to 27 degrees.

[0246] The optical system of the first embodiment disclosed above can effectively control aberration characteristics such as chromatic aberration and distortion aberration, and can have good optical performance not only at the center of the field of view (FOV) but also at the periphery.

[0247]

[0248] An optical system according to a second embodiment of the invention will be described.

[0249] FIG. 6 is a side cross-sectional view of an optical system according to a second embodiment and a camera module having the same, FIG. 7 is a table showing aspherical coefficients of aspherical lens surfaces among lenses in the optical system of FIG. 6, FIG. 8 is a table showing Sag values ​​of lens surfaces of first to eighth lenses in the optical system of FIG. 6, FIG. 9 is a graph showing data on diffraction MTF (Modulation Transfer Function) at low temperature of the optical system of FIG. 6, FIG. 10 is a graph showing data on diffraction MTF at room temperature of the optical system of FIG. 6, FIG. 11 is a graph showing data on diffraction MTF at high temperature of the optical system of FIG. 6, and FIG. 12 is a graph showing data on aberration characteristics at room temperature of the optical system of FIG. 6.

[0250] Referring to FIG. 6, the optical system (1100) includes a lens unit, and the lens unit may include a first lens (201) to an eighth lens (208). The first to eighth lenses (201 to 208) may be sequentially arranged along the optical axis (OA) of the optical system (1100). Light corresponding to information about an object may pass through the first lens (201) to the eighth lens (208) and a filter (500) and be incident on the image sensor (400).

[0251] The first lens (201) may be arranged closest to the object side. The first lens (201) may be arranged farthest from the sensor side. The first lens (201) may have negative (-) refractive power on the optical axis (OA). The first lens (201) may include a plastic material or a glass material, and may be made of glass, for example. The first lens (201) made of glass can reduce changes in the center position and radius of curvature due to temperature changes in the surrounding environment, and can protect the incident side surface of the optical system (1100).

[0252] The first surface (S1) on the object side of the first lens (201) with respect to the optical axis may be convex, and the second surface (S2) on the sensor side may be concave. The first lens (201) may have a convex meniscus shape toward the object side. The first lens (201) may have a concave meniscus shape toward the sensor side. The first lens (201) is made of glass and may have a spherical surface.

[0253] The refractive index (n1) of the first lens (201) can satisfy the condition of n1>1.6 or n1>1.7. When the refractive index (n1) of the first lens (201) satisfies the condition, the radius of curvature of the first and second lenses (201, 202) can be increased, and lens manufacturing can be facilitated. When the refractive index (n1) of the first lens (201) is smaller than the condition, the lens surface must be formed to be sharply concave or convex in order to increase the refractive power of the first and second lenses (201, 202). In this case, lens manufacturing is not easy, the lens defect rate increases, and it may cause a decrease in yield. The first surface (S1) of the first lens (201) may have a critical point from the optical axis to the end of the effective area. When the first surface (S1) has a critical point, it may be located in a range of 35% to 55%, preferably 40% to 50%, of the effective radius from the optical axis. The critical point of the first surface (S1) may be located in a range of 1.5 mm to 3.0 mm, preferably 2.0 mm to 2.5 mm from the optical axis. The critical point of the first surface (S1) is a point where the sign of the gradient value with respect to the optical axis and the direction perpendicular to the optical axis changes from positive (+) to negative (-) or from negative (-) to positive (+), and may mean a point where the gradient value is 0. In addition, the critical point of the first surface (S1) may be a point where the gradient value of the tangent line passing through the lens surface increases and then decreases, or a point where the gradient value decreases and then increases. The second surface (S2) of the first lens (201) may be provided without a critical point from the optical axis to the end of the effective area.

[0254]

[0255] The second lens (202) may be arranged second from the object side. The second lens (202) may be arranged seventh from the sensor side. The second lens (202) may be arranged between the first lens (201) and the third lens (203). The second lens (202) may have positive (+) refractive power in the optical axis (OA). The second lens (202) may include a plastic or glass material. For example, the second lens (202) may be provided as a glass material.

[0256] The third surface (S3) on the object side of the second lens (202) with respect to the optical axis (OA) may be concave, and the fourth surface (S4) on the sensor side may be convex. The second lens (202) may have a meniscus shape that is convex toward the sensor side. The second lens (202) may have a meniscus shape that is concave toward the object side. The second lens (202) is made of glass and may have a spherical surface. At least one or both of the third surface (S3) and the fourth surface (S4) may be spherical.

[0257] At least one or both of the third side (S3) and the fourth side (S4) can be provided without a critical point from the optical axis (OA) to the end of the effective area.

[0258] The aperture (Stop) may be arranged around the sensor-side fourth surface (S4) of the second lens (202). The aperture (Stop) may be arranged around the object-side fifth surface (S5) of the third lens (203). The aperture can reduce the TTL within the field of view range, and the optical system can be miniaturized. Accordingly, a decrease in the yield by weight of the optical system can be prevented, and production efficiency can be improved. In addition, the optical system can be miniaturized by reducing the TTL within the horizontal field of view (FOV_H) of 100 to 120 degrees.

[0259]

[0260] The third lens (203) may be arranged third from the object side. The third lens (203) may be arranged sixth from the sensor side. The third lens (203) may be arranged between the second lens (202) and the fourth lens (204). The third lens (203) may have positive (+) refractive power on the optical axis (OA). The third lens (203) may include a plastic or glass material. For example, the third lens (203) may be provided as a glass material.

[0261] The object-side fifth surface (S5) of the third lens (203) may be convex with respect to the optical axis, and the sensor-side sixth surface (S6) may be convex. The third lens (203) may have a convex shape on both sides. The third lens (203) may be made of glass and may be spherical. At least one or both of the fifth surface (S5) and the sixth surface (S6) may be spherical. At least one or both of the fifth surface (S5) and the sixth surface (S6) may be provided without a critical point from the optical axis (OA) to the end of the effective area.

[0262]

[0263] The fourth lens (204) may be arranged fourth from the object side. The fourth lens (204) may be arranged fifth from the sensor side. The fourth lens (204) may be arranged between the third lens (203) and the fifth lens (205). The fourth lens (204) may have negative (-) refractive power on the optical axis (OA). The fourth lens (204) may include a plastic or glass material. For example, the fourth lens (204) may be provided as a plastic material.

[0264] The object-side seventh surface (S7) of the fourth lens (204) with respect to the optical axis may be concave, and the sensor-side eighth surface (S8) may be concave. The fourth lens (204) may have a concave shape on both sides. The fourth lens (204) may be made of a plastic material and may be aspherical. At least one or both of the seventh surface (S7) and the eighth surface (S8) may be aspherical. At least one or both of the seventh surface (S7) and the eighth surface (S8) may be provided without a critical point from the optical axis (OA) to the end of the effective area.

[0265]

[0266] The fifth lens (205) may be arranged as the fifth lens from the object side. The fifth lens (205) may be arranged as the fourth lens from the sensor side. The fifth lens (205) may be arranged between the fourth lens (204) and the sixth lens (206). The fifth lens (205) may have positive (+) refractive power on the optical axis (OA). The fifth lens (205) may include a plastic or glass material. For example, the fifth lens (205) may be provided as a plastic material.

[0267] The ninth surface (S9) on the object side of the fifth lens (205) with respect to the optical axis may be convex, and the tenth surface (S10) on the sensor side may be convex. The fifth lens (205) may have a shape in which both sides are convex. The fifth lens (205) may be made of a plastic material and may be aspherical. At least one or both of the ninth surface (S9) and the tenth surface (S10) may be aspherical. At least one or both of the ninth surface (S9) and the tenth surface (S10) may be provided without a critical point from the optical axis (OA) to the end of the effective area.

[0268]

[0269] The sixth lens (206) may be arranged as the sixth lens from the object side. The sixth lens (206) may be arranged as the third lens from the sensor side. The sixth lens (206) may be arranged between the fifth lens (205) and the seventh lens (207). The sixth lens (206) may have positive refractive power on the optical axis (OA). The sixth lens (206) may include a plastic or glass material. For example, the sixth lens (206) may be provided as a plastic material.

[0270] The object-side eleventh surface (S11) of the sixth lens (206) with respect to the optical axis may be convex, and the sensor-side sixth surface (S12) may be convex. The sixth lens (206) may have a convex shape on both sides. The sixth lens (206) may be made of a plastic material and may be aspherical. At least one or both of the eleventh surface (S11) and the twelfth surface (S12) may be aspherical. At least one or both of the eleventh surface (S11) and the twelfth surface (S12) may be provided without a critical point from the optical axis (OA) to the end of the effective area.

[0271]

[0272] The seventh lens (207) may be arranged as the seventh lens from the object side. The seventh lens (207) may be arranged as the second lens from the sensor side. The seventh lens (207) may be arranged between the sixth lens (206) and the eighth lens (208). The seventh lens (207) may have negative (-) refractive power on the optical axis (OA). The seventh lens (207) may include a plastic or glass material. For example, the seventh lens (207) may be provided as a plastic material.

[0273] The object-side 13th surface (S13) of the seventh lens (207) may be convex with respect to the optical axis, and the sensor-side 14th surface (S14) may be concave. The object-side 13th surface (S13) of the seventh lens (207) may be convex with respect to the optical axis, and the sensor-side 14th surface (S14) may be concave. The seventh lens (207) may have a concave meniscus shape on the sensor side. The seventh lens (207) may have a convex meniscus shape on the object side. The seventh lens (207) may be made of a plastic material and may be aspherical. At least one or both of the 13th surface (S13) and the 14th surface (S14) may be aspherical.

[0274] The thirteenth surface (S13) of the seventh lens (207) may have a critical point from the optical axis to the end of the effective area. When the thirteenth surface (S13) has a critical point, it may be located in a range of 30% to 50%, preferably 35% to 40%, of the effective radius from the optical axis. The critical point of the thirteenth surface (S13) may be located in a range of 1.0 mm to 2.5 mm, preferably 1.5 mm to 2.0 mm, from the optical axis. The critical point of the thirteenth surface (S13) may be a point where the sign of the gradient value with respect to the optical axis and the direction perpendicular to the optical axis changes from positive (+) to negative (-) or from negative (-) to positive (+), and may mean a point where the gradient value is 0. In addition, the critical point of the thirteenth surface (S13) may be a point where the gradient value of a tangent passing through the lens surface increases and then decreases, or a point where the gradient value decreases and then increases.

[0275] The 14th surface (S14) of the 7th lens (207) can be provided without a critical point from the optical axis to the end of the effective area.

[0276]

[0277] The eighth lens (208) may be arranged as the eighth lens from the object side. The eighth lens (208) may be arranged closest to the sensor side. The eighth lens (208) may have positive refractive power on the optical axis (OA). The eighth lens (208) may include a plastic or glass material. For example, the eighth lens (208) may be provided as a plastic material.

[0278] The object-side 15th surface (S15) of the eighth lens (208) with respect to the optical axis may be convex, and the sensor-side 16th surface (S16) may be concave. The eighth lens (208) may have a concave meniscus shape on the sensor side. The eighth lens (208) may have a convex meniscus shape on the object side. The eighth lens (208) may be made of a plastic material and may be aspherical. At least one or both of the 15th surface (S15) and the 16th surface (S16) may be aspherical. The 15th surface (S15) of the eighth lens (208) may be provided without a critical point from the optical axis to the end of the effective area.

[0279] The sixteenth surface (S16) of the eighth lens (208) may have a critical point from the optical axis to the end of the effective area. When the sixteenth surface (S16) has a critical point, it may be located in a range of 75% to 90%, preferably in a range of 80% to 85%, of the effective radius from the optical axis. The critical point of the sixteenth surface (S16) may be located in a range of 3.5 mm to 5.0 mm, preferably in a range of 4.0 mm to 4.5 mm from the optical axis. The critical point of the sixteenth surface (S16) may be a point where the sign of the gradient value with respect to the optical axis and the direction perpendicular to the optical axis changes from positive (+) to negative (-) or from negative (-) to positive (+), and may mean a point where the gradient value is 0. In addition, the critical point of the sixteenth surface (S16) may be a point where the gradient value of a tangent passing through the lens surface increases and then decreases, or a point where the gradient value decreases and then increases.

[0280]

[0281] LensSurfaceRadiusThicknessndvdSemiApertureFocal length1S1100.0001.0001.69453.2015.124-6.651 S24.4052.765 3.732 2S1-30.4683.0001.94617.9423.69223.929 S2-13.6890.743 3.776 STOP(STOP) Infinity0.613 3.490 3S111.8173.2321.43795.1003.75510.669 S2-7.0820.579 3.831 4S1-10.4301.0001.61425.5803.600-11.913 S226.0310.654 3.900 5S115.4382.9841.53655.9814.34716.811 S2-20.3840.367 4.602 6S110.1453.0001.53655.9814.61413.677 S2-24.0540.129 4.600 7S128.9411.2001.61425.5804.427-18.350 S28.0242.031 4.415 8S15.9172.3001.53655.9814.75448.642 S26.6060.995 5.100 FilterS1Infinity0.900 5.063 S2Infinity2.498 5.078 ImageImageInfinity0.001 5.143

[0282] Table 3 shows the surface number (Surface), radius of curvature (Radius), center thickness of each lens or distance between lens surfaces (Thickness), refractive index (Index,nd), Abbe number (Abbe,vd), effective radius (Semi Aperture), and focal length (Fcoal length) of the lens according to the second embodiment of the present invention. At this time, the unit of the radius of curvature and thickness or distance may be mm.

[0283]

[0284] Item ValueItem ValueF6.210ET12.924ΣIndex12.914ET22.693ΣAbbe385.345ET31.494ΣCT17.716ET41.992ΣCG7.268ET51.482CA_max10.248ET61.469CA_min6.980ET72.29 6CA_Aver8.254ET82.074CT_max3.232F-number1.650CT_min1.000HFOV106.000CT_Aver2.215ImgH10.286EPD3.764SD19.086BFL4.395TTL29.99252TD26.593

[0285] Table 4 shows the items of the mathematical formulas described above in the optical system (1100) of the embodiment, including the total track length (TTL) (mm), back focal length (BFL), effective focal length (F) (mm), ImgH (mm), effective diameter (CA) (mm), thickness (mm), TTL (mm), the optical axis distance from the first surface (S1) to the eighth surface (S8) TD (mm), the optical axis distance from the aperture (Stop) to the eighth surface (S8) SD (mm), the sum of refractive indices, the sum of Abbe numbers, the sum of thicknesses (mm), the sum of spacings between adjacent lenses, effective diameter characteristics, horizontal field of view (HFOV) (Degree), edge thickness (ET), F number, etc. of the optical system (1100).

[0286] The center thicknesses of the first to eighth lenses (201 to 208) are represented by CT1 to CT8, the edge thicknesses at the ends of the effective areas of each lens are represented by ET1 to ET8, the center gap between two adjacent lenses is represented by CG1 to CG7, and the edge gaps between the edges of each lens are represented by EG1 to EG8. The BFL (Back focal length) is the optical axis distance from the image sensor (400) to the center of the last lens. The TTL is the optical axis distance from the center of the first surface (S1) of the first lens (201) to the upper surface of the image sensor (400).

[0287] As shown in FIG. 7, among the lenses of the lens unit of the second embodiment, the lens surfaces of the first lens (201), the fourth lens (204), the fifth lens (205), the sixth lens (206), the seventh lens (207), and the eighth lens (208) may include aspherical surfaces having a 30th-order aspherical coefficient. For example, the first lens (201), the fourth lens (204), the fifth lens (205), the sixth lens (206), the seventh lens (207), and the eighth lens (208) may include lens surfaces having a 30th-order aspherical coefficient. As described above, since the aspherical surface having a 30th-order aspherical coefficient (a value other than "0") can significantly change the aspherical shape of the periphery, the optical performance of the periphery of the field of view (FOV) can be well corrected.

[0288] When comparing the absolute values ​​of the curvature radii of each lens, the curvature radii of the first surface (S1) of the first lens (201) on the optical axis (OA) may be the largest among the lenses, and the curvature radii of the second surface (S2) of the first lens (201) may be the smallest among the lenses. The difference between the maximum curvature radii and the minimum curvature radii may be 15 times or more, for example, in the range of 20 to 25 times. The curvature radii of the sensor-side surface of the first lens (201) arranged on the object side of the second lens (202) may be the smallest among the lenses.

[0289] In temperature-compensated designs that require maintaining resolution across temperatures ranging from -40 to 100 degrees Celsius, a larger radius of curvature can be advantageous. Aluminum lens barrels can be used for temperature compensation. Aluminum barrels have large manufacturing tolerances, which can significantly misalign the optical axes of individual lenses during assembly. Therefore, a larger radius of curvature can be used to reduce sensitivity to manufacturing tolerances.

[0290] The fourth to eighth lenses (204 to 208) having aspherical shapes can be designed to have gentle shapes. If the aspherical surface is positioned at the frontmost position in the optical system (1100), the performance of the lens is improved, but the assemblability may be reduced. To improve the assemblability, the shapes of the fourth to eighth lenses (204 to 208) should be designed to have gentle shapes. In order to minimize the influence on the lens placed on the sensor side when assembling the lens in the barrel, the lens can be designed to have almost no curvature.

[0291] Both the object-side and sensor-side surfaces of the seventh lens (207) and the eighth lens (208) may include inflection points and may have a gull-shaped shape (a shape including both concave and convex shapes). Accordingly, when a lens positioned adjacent to the image sensor (400) has an inflection point, the performance of aberrations (e.g., distortion aberration, coma aberration in the peripheral field, etc.) relative to the axis may be improved.

[0292] The second lens (202) may have a meniscus shape toward the sensor side, and the third lens (203) may have a biconvex shape. Since the second lens (202) has a meniscus shape, the effective diameter of the first lens (201) is reduced, and since the third lens (203) has a biconvex shape made of glass, temperature compensation is easy and aberration correction is effective. In order to correct aberration and form an appropriate focal length, the lens arranged adjacent to the aperture (STOP) may have a biconvex shape. For example, the third lens arranged on the sensor side of the aperture (STOP) may have a biconvex shape.

[0293] The absolute value of the curvature radius of the first surface (S1) of the first lens (201) may be greater than the absolute value of the curvature radius of the second surface (S2). The absolute value of the curvature radius of the third surface (S3) of the second lens (202) may be greater than the absolute value of the curvature radius of the fourth surface (S4). The absolute value of the curvature radius of the fifth surface (S5) of the third lens (203) may be greater than the absolute value of the curvature radius of the sixth surface (S6). The absolute value of the curvature radius of the seventh surface (S7) of the fourth lens (204) may be less than the absolute value of the curvature radius of the eighth surface (S8). The absolute value of the curvature radius of the ninth surface (S9) of the fifth lens (205) may be less than the absolute value of the curvature radius of the tenth surface (S10). The absolute value of the curvature radius of the eleventh surface (S11) of the sixth lens (206) may be smaller than the absolute value of the curvature radius of the twelfth surface (S12). The absolute value of the curvature radius of the thirteenth surface (S13) of the seventh lens (207) may be larger than the absolute value of the curvature radius of the fourteenth surface (S14). The absolute value of the curvature radius of the fifteenth surface (S15) of the eighth lens (208) may be smaller than the absolute value of the curvature radius of the sixteenth surface (S16).

[0294] When the curvature radius of the object-side surface and the sensor-side surface of the first lens (201) satisfy condition 1 below, the object-side surface of the first lens (201) can be formed into a shape close to a plane, so that the refractive power of the first lens (201) can be designed to be large, and the curvature of the sensor-side surface of the first lens (201) can be designed to be small, so that an appropriate angle of view can be set for the optical system.

[0295] The ratio of the radius of curvature of each lens can satisfy the following conditions.

[0296] Condition 1: 20 < |L1R1 / L1R2| < 25

[0297] Condition 2: 2 < |L2R1 / L2R2| < 2.5

[0298] Condition 3: 1.5 < |L3R1 / L3R2| < 2

[0299] Condition 4: 0.1 < |L4R1 / L4R2| < 0.5

[0300] Condition 5: 0.5 < |L5R1 / L5R2| < 1

[0301] Condition 6: 0.1 < |L6R1 / L6R2| < 0.5

[0302] Condition 7: 3 < |L7R1 / L7R2| < 5

[0303] Condition 8: 0.5 < |L8R1 / L8R2| < 1

[0304]

[0305] When describing the central thickness of the lenses based on the optical axis, the central thickness (CT3) of the third lens (203) is the largest among the lenses, and the central thickness (CT1) of the first lens (201) is the smallest among the lenses. The difference between the maximum and minimum central thicknesses among the lenses may be in the range of 2 mm or more and 3 mm or less.

[0306] The central thickness of each lens may satisfy any one of the following conditions:

[0307] Condition 1: CT2, CT3, CT4, CT5, CT6, CT7, CT8 > CT1

[0308] Condition 2: CT3 > CT2 > CT1, CT4, CT5, CT6, CT7, CT8

[0309] Condition 3: CT3 > CT1, CT2, CT4, CT5, CT6, CT7, CT8

[0310] Condition 4: CT2, CT3, CT5, CT6, CT7, CT8 > CT4 > CT1

[0311] Condition 5: CT2, CT3, CT6 > CT5 > CT1, CT4, CT7, CT8

[0312] Condition 6: CT2, CT3 > CT6 > CT1, CT4, CT5, CT7, CT8

[0313] Condition 7: CT2, CT3, CT5, CT6, CT8 > CT7 > CT1, CT4

[0314] Condition 8: CT2, CT3, CT5, CT6 > CT8 > CT1, CT4, CT7

[0315]

[0316] When describing the center spacing (CG) between the lenses, the center spacing (CG1) between the first lens (201) and the second lens (202) may be the maximum, and the center spacing (CG6) between the sixth and seventh lenses (206, 207) may be the minimum. The difference between the maximum center spacing and the minimum center spacing among the spaced lens spacings may be 2 mm or more, for example, in the range of 2.5 mm to 3.0 mm.

[0317] The center spacing between each lens can satisfy the conditions below.

[0318] Condition 1: CG1 > CG2, CG3, CG4, CG5, CG6, CG7

[0319] Condition 2: CG1, CG7 > CG2 > CG3, CG4, CG5, CG6

[0320] Condition 3: CG1, CG2, CG4, CG7 > CG3 > CG5, CG6

[0321] Condition 4: CG1, CG2, CG7 > CG4 > CG3, CG5, CG6

[0322] Condition 5: CG1, CG2, CG3, CG4, CG7 > CG5 > CG6

[0323] Condition 6: CG1, CG2, CG3, CG4, CG5, CG7 > CG6

[0324] Condition 7: CG1 > CG7 > CG2, CG3, CG4, CG5, CG6

[0325]

[0326] Regarding the effective diameter, the effective diameter of the eighth lens (208) closest to the sensor side is the maximum, and the lens with the maximum effective diameter may be a plastic lens. The lens with the maximum effective diameter may be the eighth lens (208). Here, the effective diameter is the average of the effective diameters of the object-side surface and the sensor-side surface of each lens. The lens surface with the maximum effective diameter may be the first surface (S1) of the first lens (201).

[0327] The lens having the minimum effective diameter may be any one of the glass material lenses, and for example, the effective diameter of the second lens (202) may be the minimum within the lens unit. The lens surface having the minimum effective diameter may be the seventh surface (S7) of the fourth lens (204).

[0328] The effective diameter may decrease from the first lens (201) to the second lens (202), and may increase from the fourth lens (204) to the fifth lens (205). Here, the effective diameter of each lens may mean the average of the effective diameter values ​​of the object-side surface of the lens and the effective diameter values ​​of the sensor-side surface of the lens. The average effective diameter values ​​of the object-side and sensor-side surfaces of each lens may decrease from the first lens (201) to the second lens (202), and may increase from the fourth lens (204) to the fifth lens (205). The position of the aperture (STOP) having a small effective diameter is arranged on the sensor side of the second lens (202), and the position of the aperture (STOP) is relatively closer to the object side than to the sensor side, so that the effective diameter of the first lens (201) may decrease.

[0329] The average effective diameter of the object-side and sensor-side surfaces of each glass lens positioned closer to the object side than the plastic lens may be smaller than the average effective diameter of the object-side and sensor-side surfaces of each plastic lens. Alternatively, the effective diameter of the glass lens positioned on the object side of the plastic lens may have the smallest effective diameter in the optical system (1100). For example, when the fourth to eighth lenses (204 to 208) are made of plastic and the third lens (203) is made of glass, the average effective diameter of the object-side and sensor-side surfaces of the third lens (203) may be smaller than the average of the effective diameters of the object-side and sensor-side surfaces of the fourth to eighth lenses (204 to 208). In addition, the average effective diameter of the object-side and sensor-side surfaces of the third lens (203) may have the smallest effective diameter in the optical system (1100). Among the first to eighth lenses (201-208), a plurality of lenses sequentially arranged may be made of glass, and the remaining lenses sequentially arranged may be made of plastic. Among the first to eighth lenses (201-208), the effective diameter of the glass lens arranged closest to the lens made of plastic may be the smallest.

[0330] In relation to the above, an inner barrel may be additionally positioned between the plastic lens and the glass lens to minimize changes in optical performance due to changes in the shape of the plastic lens that expands at high temperatures. Alternatively, a partition wall protruding into the lens barrel may be formed between the plastic lens and the glass lens to prevent interference due to the high-temperature expansion of the plastic lens.

[0331] The effective diameter of each lens can satisfy any one of the conditions below.

[0332] Condition 1: CA_L5, CA_L6, CA_L8 > CA_L1 > CA_L2, CA_L3, CA_L4, CA_L7

[0333] Condition 2: CA_L1, CA_L3, CA_L4, CA_L5, CA_L6, CA_L7, CA_L8 > CA_L2

[0334] Condition 3: CA_L1, CA_L5, CA_L6, CA_L7, CA_L8 > CA_L3 > CA_L2, CA_L4

[0335] Condition 4: CA_L1, CA_L3, CA_L5, CA_L6, CA_L7, CA_L8 > CA_L4 > CA_L2

[0336] Condition 5: CA_L6, CA_L8 > CA_L5 > CA_L1, CA_L2, CA_L3, CA_L4, CA_L7

[0337] Condition 6: CA_L8 > CA_L6 > CA_L1, CA_L2, CA_L3, CA_L4, CA_L5, CA_L7

[0338] Condition 7: CA_L1, CA_L5, CA_L6, CA_L8 > CA_L7 > CA_L2, CA_L3, CA_L4

[0339] Condition 8: CA_L8 > CA_L1, CA_L2, CA_L3, CA_L4, CA_L5, CA_L6, CA_L7

[0340]

[0341] Regarding the refractive index, the refractive index of the second lens (202) may be the highest among the lenses and may be greater than 1.8, for example, greater than 1.9. The third lens (203) may have the lowest refractive index among the lenses. For example, the refractive index of the third lens (203) may be the lowest among the lenses and may be less than 1.5, for example, less than 1.45. The difference between the maximum refractive index and the minimum refractive index may be 0.4 or more.

[0342] The refractive index of each lens can satisfy any of the conditions below.

[0343] Condition 1: n2 > n1 > n3, n4, n5, n6, n7, n8

[0344] Condition 2: n2 > n1, n3, n4, n5, n6, n7, n8

[0345] Condition 3: n1, n2, n4, n5, n6, n7, n8 > n3

[0346] Condition 4: n1, n2 > n4 = n7 > n3, n5, n6, n8

[0347] Condition 5: n1, n2, n4, n7 > n5 = n6 = n8 > n3

[0348]

[0349] Comparing the Abbe numbers, the Abbe number of the third lens (203) is the largest among the lenses and may be 90 or greater. The Abbe number of the second lens (202) is the smallest among the lenses and may be 20 or less. The difference between the maximum Abbe number and the minimum Abbe number may be 70 or greater.

[0350] The Abbe number of each lens can satisfy any of the conditions below.

[0351] Condition 1: v3, v5, v6, v8 > v1 > v2, v4, v7

[0352] Condition 2: v1, v3, v4, v5, v6, v7, v8 > v2

[0353] Condition 3: v3 > v1, v2, v4, v5, v6, v7, v8

[0354] Condition 4: v1, v3, v5, v6, v8 > v4 = v7 > v2

[0355] Condition 5: v3 > v5 = v6 = v8 > v1, v2, v4, v7

[0356]

[0357] The focal lengths (F2, F3, F5, F6, F8) of the second, third, fifth, sixth, and eighth lenses (202, 203, 205, 206, and 208) may have positive (+) signs. The second, third, fifth, sixth, and eighth lenses (202, 203, 205, 206, and 208) may have positive (+) refractive power. The focal lengths (F1, F4, and F7) of the first, fourth, and seventh lenses (201, 204, and 207) may have negative (-) signs. The first, fourth, and seventh lenses (201, 204, and 207) may have negative (-) refractive power. A fourth lens (204) having negative (-) refractive power may be arranged on the sensor side of the third lens (203) having positive (+) refractive power. Through this, light incident from the object side can gather in the direction of the optical axis and then move away from the direction of the optical axis, thereby forming a stable optical path.

[0358]

[0359] When comparing the focal lengths in absolute values, the focal length of the eighth lens (208) is the largest among the lenses, and may be 20 or more and 50 or less. Among the lenses, the eighth lens (208) made of plastic may have the largest focal length and the smallest refractive power. The focal length of the first lens (201) is the smallest among the lenses, and the absolute value of the focal length of the first lens (201) may be 5 or more and 10 or less. Among the lenses, the first lens (201) made of glass may have the smallest focal length and the largest refractive power.

[0360] Among the lenses, the lens having the minimum focal length may be the first lens (201). The difference between the maximum focal length and the minimum focal length may be 30 or more or 50 or more. Accordingly, the optical system may have improved MTF characteristics, aberration control characteristics, resolution characteristics, etc. in the set field of view range, and may have good optical performance in the periphery of the field of view.

[0361] The absolute value of the focal length of each lens can satisfy any of the conditions below.

[0362] Condition 1: |f2|, |f3|, |f4|, |f5|, |f6|, |f7|, |f8| > |f1|

[0363] Condition 2: |f8| > |f2| > |f1|, |f3|, |f4|, |f5|, |f6|, |f7|

[0364] Condition 3: |f2|, |f4|, |f5|, |f6|, |f7|, |f8| > |f3| > |f1|

[0365] Condition 4: |f2|, |f5|, |f6|, |f7|, |f8| > |f4| > |f1|, |f3|

[0366] Condition 5: |f2|, |f7|, |f8| > |f5| > |f1|, |f3|, |f4|, |f6|

[0367] Condition 6: |f2|, |f5|, |f7|, |f8| > |f6| > |f1|, |f3|, |f4|

[0368] Condition 7: |f2|, |f8| > |f7| > |f1|, |f3|, |f4|, |f5|, |f6|

[0369] Condition 8: |f8| > |f1|, |f2|, |f3|, |f4|, |f5|, |f6|, |f7|

[0370]

[0371] The thickness (T1) of the first lens (201) may be maximum at the edge and minimum at the center, and the maximum thickness is in the range of 2.5 to 3 times the minimum thickness. The thickness (T2) of the second lens (202) may be minimum at the edge and maximum at the center, and the maximum thickness is in the range of 1 to 1.5 times the minimum thickness. The thickness (T3) of the third lens (203) may be maximum at the center and minimum at the edge, and the maximum thickness is in the range of 2 to 2.5 times the minimum thickness. The thickness (T4) of the fourth lens (204) may be minimum at the center and maximum at the edge, and the maximum thickness is in the range of 1.5 to 2 times the minimum thickness. The thickness (T5) of the fifth lens (205) may be maximum at the center and minimum at the edge, and the maximum thickness is in the range of 2 to 2.5 times the minimum thickness. The thickness (T6) of the sixth lens (206) may be maximum at the center and minimum at the edge, and the maximum thickness is in the range of 2 to 2.5 times the minimum thickness. The thickness (T7) of the seventh lens (207) may be minimum at the center and maximum at the edge, and the maximum thickness is in the range of 1.5 to 2 times the minimum thickness. The thickness (T8) of the eighth lens (208) may be maximum at the center and minimum at the edge, and the maximum thickness is in the range of 1 to 1.5 times the minimum thickness.

[0372] The thickness of each lens can satisfy any of the conditions below.

[0373] Condition 1: 0.1 < CT1 / ET1 < 0.5, 2.5 < ET1 / CT1 < 3

[0374] Condition 2: 1 < CT2 / ET2 < 1.5, 0.5 < ET2 / CT2 < 1

[0375] Condition 3: 2 < CT3 / ET3 < 2.5, 0.1 < ET3 / CT3 < 0.5

[0376] Condition 4: 0.5 < CT4 / ET4 < 1, 1.5 < ET4 / CT4 < 2

[0377] Condition 5: 2 < CT5 / ET5 < 2.5, 0.1 < ET5 / CT5 < 0.5

[0378] Condition 6: 2 < CT6 / ET6 < 2.5, 0.1 < ET6 / CT6 < 0.5

[0379] Condition 7: 0.5 < CT7 / ET7 < 1, 1.5 < ET7 / CT7 < 2

[0380] Condition 8: 1 < CT8 / ET8 < 1.5, 0.5 < ET8 / CT8 < 1

[0381] Condition 9: 1 < ΣCT / ΣET < 1.5, 0.5 < ΣET / ΣCT < 1

[0382]

[0383] Among the gaps (G1-G7) between the lenses, the first gap (G1) between the first and second lenses (201, 202) may have a maximum in the center and a minimum in the edge. The second gap (G2) between the second and third lenses (202, 203) may have a minimum in the center and a maximum in the edge. The third gap (G3) between the third and fourth lenses (203, 204) may have a maximum in the edge and a minimum in the center. The fourth gap (G4) between the fourth and fifth lenses (204, 205) may have a maximum in the edge and a minimum in the center. The fifth gap (G5) between the fifth and sixth lenses (205, 206) may have a maximum in the edge and a minimum in the center. The sixth gap (G6) between the sixth and seventh lenses (206, 207) may have a maximum in the edge and a minimum in the center. The seventh gap (G7) between the seventh and eighth lenses (207, 208) may be maximum at the edge and minimum at the center.

[0384]

[0385] FIGS. 9, 10, and 11 are graphs showing the diffraction MTF (Modulation Transfer Function) at room temperature, low temperature, and high temperature in the optical system of FIG. 6, and are graphs showing the modulation ratio according to spatial frequency. As shown in FIGS. 9, 10, and 11, in the second embodiment of the invention, the deviation of the MTF at low temperature or high temperature based on room temperature may be less than 10%, that is, 7% or less.

[0386] Fig. 12 is a graph showing the aberration characteristics at room temperature in the optical system of Fig. 6. In the aberration graph of Fig. 12, spherical aberration (longitudinal spherical aberration), astigmatic field curves, and distortion are measured from left to right. In Fig. 12, 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. In addition, the graph for spherical aberration is a graph for light in wavelength bands of about 435 nm, about 486 nm, about 546 nm, about 587 nm, and about 656 nm, and the graphs for astigmatism and distortion are graphs for light in wavelength bands of about 546 nm. In the aberration diagram of Fig. 12, the closer each curve at room temperature is to the Y-axis, the better the aberration correction function can be interpreted. In the optical system (1100) according to the second embodiment, it can be seen that the measured values ​​are close to the Y-axis in almost all areas. That is, the optical system (1100) according to the second embodiment 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. Here, the room temperature can be in the range of 22 degrees ± 5 degrees or in the range of 18 degrees to 27 degrees.

[0387] The optical system of the second embodiment disclosed above can effectively control aberration characteristics such as chromatic aberration and distortion aberration, and can have good optical performance not only at the center of the field of view (FOV) but also at the periphery.

[0388]

[0389] An optical system according to a third embodiment of the invention will be described.

[0390] FIG. 13 is a side cross-sectional view of an optical system according to a third embodiment and a camera module having the same, FIG. 14 is a table showing aspherical coefficients of aspherical lens surfaces among lenses in the optical system of FIG. 13, FIG. 15 is a table showing Sag values ​​of lens surfaces of the first to eighth lenses in the optical system of FIG. 13, FIG. 16 is a graph showing data on diffraction MTF (Modulation Transfer Function) at low temperature of the optical system of FIG. 13, FIG. 17 is a graph showing data on diffraction MTF at room temperature of the optical system of FIG. 13, FIG. 18 is a graph showing data on diffraction MTF at high temperature of the optical system of FIG. 13, and FIG. 19 is a graph showing data on aberration characteristics at room temperature of the optical system of FIG. 13.

[0391] Referring to FIG. 13, the optical system (1200) includes a lens unit, and the lens unit may include a first lens (301) to an eighth lens (308). The first to eighth lenses (301 to 308) may be sequentially arranged along the optical axis (OA) of the optical system (1200). Light corresponding to information about an object may pass through the first lens (301) to the eighth lens (308) and a filter (500) and be incident on the image sensor (400).

[0392] The first lens (301) may be arranged closest to the object side. The first lens (301) may be arranged farthest from the sensor side. The first lens (301) may have negative (-) refractive power on the optical axis (OA). The first lens (301) may include a plastic material or a glass material, and may be made of glass, for example. The first lens (301) made of glass can reduce changes in the center position and radius of curvature due to temperature changes in the surrounding environment, and can protect the incident side surface of the optical system (1200).

[0393] The first surface (S1) on the object side of the first lens (301) with respect to the optical axis may be convex, and the second surface (S2) on the sensor side may be concave. The first lens (301) may have a convex meniscus shape toward the object side. The first lens (301) may have a concave meniscus shape toward the sensor side. The first lens (301) is made of glass and may have a spherical surface.

[0394] The refractive index (n1) of the first lens (301) can satisfy the condition of n1>1.6 or n1>1.65. When the refractive index (n1) of the first lens (301) satisfies the condition, the radius of curvature of the first and second lenses (301, 302) can be increased, and lens manufacturing can be facilitated. When the refractive index (n1) of the first lens (301) is smaller than the condition, the lens surface must be formed to be sharply concave or convex in order to increase the refractive power of the first and second lenses (301, 302). In this case, lens manufacturing is not easy, the lens defect rate increases, and it may cause a decrease in yield. The first surface (S1) of the first lens (301) may have a critical point from the optical axis to the end of the effective area. When the first surface (S1) has a critical point, it may be located in a range of 40% to 60%, preferably 50% to 55%, of the effective radius from the optical axis. The critical point of the first surface (S1) may be located in a range of 1.5 mm to 3.5 mm, preferably 2.5 mm to 3.0 mm from the optical axis. The critical point of the first surface (S1) is a point where the sign of the gradient value with respect to the optical axis and the direction perpendicular to the optical axis changes from positive (+) to negative (-) or from negative (-) to positive (+), and may mean a point where the gradient value is 0. In addition, the critical point of the first surface (S1) may be a point where the gradient value of a tangent line passing through the lens surface increases and then decreases, or a point where the gradient value decreases and then increases. The second surface (S2) of the first lens (301) may be provided without a critical point from the optical axis to the end of the effective area.

[0395]

[0396] The second lens (302) may be arranged second from the object side. The second lens (302) may be arranged seventh from the sensor side. The second lens (302) may be arranged between the first lens (301) and the third lens (303). The second lens (302) may have positive (+) refractive power on the optical axis (OA). The second lens (302) may include a plastic or glass material. For example, the second lens (302) may be provided as a glass material.

[0397] The third surface (S3) on the object side of the second lens (302) with respect to the optical axis (OA) may be concave, and the fourth surface (S4) on the sensor side may be convex. The second lens (302) may have a meniscus shape that is convex toward the sensor side. The second lens (302) may have a meniscus shape that is concave toward the object side. The second lens (302) is made of glass and may have a spherical surface. At least one or both of the third surface (S3) and the fourth surface (S4) may be spherical.

[0398] At least one or both of the third side (S3) and the fourth side (S4) can be provided without a critical point from the optical axis (OA) to the end of the effective area.

[0399] The aperture (Stop) may be arranged around the sensor-side fourth surface (S4) of the second lens (302). The aperture (Stop) may be arranged around the object-side fifth surface (S5) of the third lens (303). The aperture can reduce the TTL within the field of view range, and the optical system can be miniaturized. Accordingly, a decrease in the yield by weight of the optical system can be prevented, and production efficiency can be improved. In addition, the optical system can be miniaturized by reducing the TTL within the horizontal field of view (FOV_H) of 100 to 120 degrees.

[0400]

[0401] The third lens (303) may be arranged third from the object side. The third lens (303) may be arranged sixth from the sensor side. The third lens (303) may be arranged between the second lens (302) and the fourth lens (304). The third lens (303) may have positive (+) refractive power on the optical axis (OA). The third lens (303) may include a plastic or glass material. For example, the third lens (303) may be provided as a glass material.

[0402] The object-side fifth surface (S5) of the third lens (303) may be convex with respect to the optical axis, and the sensor-side sixth surface (S6) may be convex. The third lens (303) may have a convex shape on both sides. The third lens (303) may be made of glass and may be spherical. At least one or both of the fifth surface (S5) and the sixth surface (S6) may be spherical. At least one or both of the fifth surface (S5) and the sixth surface (S6) may be provided without a critical point from the optical axis (OA) to the end of the effective area.

[0403]

[0404] The fourth lens (304) may be arranged fourth from the object side. The fourth lens (304) may be arranged fifth from the sensor side. The fourth lens (304) may be arranged between the third lens (303) and the fifth lens (305). The fourth lens (304) may have negative refractive power on the optical axis (OA). The fourth lens (304) may include a plastic or glass material. For example, the fourth lens (304) may be provided as a plastic material.

[0405] The object-side seventh surface (S7) of the fourth lens (304) with respect to the optical axis may be concave, and the sensor-side eighth surface (S8) may be concave. The fourth lens (304) may have a concave shape on both sides. The fourth lens (304) may be made of a plastic material and may be aspherical. At least one or both of the seventh surface (S7) and the eighth surface (S8) may be aspherical. At least one or both of the seventh surface (S7) and the eighth surface (S8) may be provided without a critical point from the optical axis (OA) to the end of the effective area.

[0406]

[0407] The fifth lens (305) may be arranged as the fifth lens from the object side. The fifth lens (305) may be arranged as the fourth lens from the sensor side. The fifth lens (305) may be arranged between the fourth lens (304) and the sixth lens (306). The fifth lens (305) may have positive (+) refractive power on the optical axis (OA). The fifth lens (305) may include a plastic or glass material. For example, the fifth lens (305) may be provided as a plastic material.

[0408] The ninth surface (S9) on the object side of the fifth lens (305) with respect to the optical axis may be convex, and the tenth surface (S10) on the sensor side may be convex. The fifth lens (305) may have a shape in which both sides are convex. The fifth lens (305) may be made of a plastic material and may be aspherical. At least one or both of the ninth surface (S9) and the tenth surface (S10) may be aspherical. At least one or both of the ninth surface (S9) and the tenth surface (S10) may be provided without a critical point from the optical axis (OA) to the end of the effective area.

[0409]

[0410] The sixth lens (306) may be arranged as the sixth lens from the object side. The sixth lens (306) may be arranged as the third lens from the sensor side. The sixth lens (306) may be arranged between the fifth lens (305) and the seventh lens (307). The sixth lens (306) may have positive refractive power on the optical axis (OA). The sixth lens (306) may include a plastic or glass material. For example, the sixth lens (306) may be provided as a plastic material.

[0411] The object-side eleventh surface (S11) of the sixth lens (306) with respect to the optical axis may be convex, and the sensor-side sixth surface (S12) may be convex. The sixth lens (306) may have a convex shape on both sides. The sixth lens (306) may be made of a plastic material and may be aspherical. At least one or both of the eleventh surface (S11) and the twelfth surface (S12) may be aspherical. At least one or both of the eleventh surface (S11) and the twelfth surface (S12) may be provided without a critical point from the optical axis (OA) to the end of the effective area.

[0412]

[0413] The seventh lens (307) may be arranged as the seventh lens from the object side. The seventh lens (307) may be arranged as the second lens from the sensor side. The seventh lens (307) may be arranged between the sixth lens (306) and the eighth lens (308). The seventh lens (307) may have negative (-) refractive power on the optical axis (OA). The seventh lens (307) may include a plastic or glass material. For example, the seventh lens (307) may be provided as a plastic material.

[0414] The object-side 13th surface (S13) of the seventh lens (307) may be convex with respect to the optical axis, and the sensor-side 14th surface (S14) may be concave. The object-side 13th surface (S13) of the seventh lens (307) may be convex with respect to the optical axis, and the sensor-side 14th surface (S14) may be concave. The seventh lens (307) may have a concave meniscus shape on the sensor side. The seventh lens (307) may have a convex meniscus shape on the object side. The seventh lens (307) may be made of a plastic material and may be aspherical. At least one or both of the 13th surface (S13) and the 14th surface (S14) may be aspherical.

[0415] The thirteenth surface (S13) of the seventh lens (307) may have a critical point from the optical axis to the end of the effective area. When the thirteenth surface (S13) has a critical point, it may be located in a range of 50% to 65%, preferably 55% to 60%, of the effective radius from the optical axis. The critical point of the thirteenth surface (S13) may be located in a range of 2.0 mm to 3.5 mm, preferably 2.5 mm to 3.0 mm from the optical axis. The critical point of the thirteenth surface (S13) may be a point where the sign of the gradient value with respect to the optical axis and the direction perpendicular to the optical axis changes from positive (+) to negative (-) or from negative (-) to positive (+), and may mean a point where the gradient value is 0. In addition, the critical point of the thirteenth surface (S13) may be a point where the gradient value of a tangent passing through the lens surface increases and then decreases, or a point where the gradient value decreases and then increases.

[0416] The 14th surface (S14) of the 7th lens (307) can be provided without a critical point from the optical axis to the end of the effective area.

[0417]

[0418] The eighth lens (308) may be arranged as the eighth lens from the object side. The eighth lens (308) may be arranged closest to the sensor side. The eighth lens (308) may have positive refractive power on the optical axis (OA). The eighth lens (308) may include a plastic or glass material. For example, the eighth lens (308) may be provided as a plastic material.

[0419] The object-side 15th surface (S15) of the eighth lens (308) may be convex with respect to the optical axis, and the sensor-side 16th surface (S16) may be concave. The eighth lens (308) may have a concave meniscus shape on the sensor side. The eighth lens (308) may have a convex meniscus shape on the object side. The eighth lens (308) may be made of a plastic material and may be aspherical. At least one or both of the 15th surface (S15) and the 16th surface (S16) may be aspherical. The 15th surface (S15) of the 8th lens (308) may have a critical point from the optical axis to the end of the effective area. When the 15th surface (S15) has a critical point, it may be located in a range of 75% to 90%, preferably in a range of 80% to 85%, of the effective radius from the optical axis. The critical point of the fifteenth surface (S15) may be located in a range of 3.0 mm to 4.5 mm from the optical axis, preferably in a range of 3.5 mm to 4.0 mm. The critical point of the fifteenth surface (S15) may be a point where the sign of the gradient value with respect to the optical axis and the direction perpendicular to the optical axis changes from positive (+) to negative (-) or from negative (-) to positive (+), and may mean a point where the gradient value is 0. In addition, the critical point of the fifteenth surface (S15) may be a point where the gradient value of a tangent line passing through the lens surface increases and then decreases, or a point where the gradient value decreases and then increases.

[0420] The sixteenth surface (S16) of the eighth lens (308) may have a critical point from the optical axis to the end of the effective area. When the sixteenth surface (S16) has a critical point, it may be located in a range of 60% to 80%, preferably in a range of 65% to 75%, of the effective radius from the optical axis. The critical point of the sixteenth surface (S16) may be located in a range of 2.5 mm to 4.0 mm, preferably in a range of 3.0 mm to 3.5 mm from the optical axis. The critical point of the sixteenth surface (S16) may be a point where the sign of the gradient value with respect to the optical axis and the direction perpendicular to the optical axis changes from positive (+) to negative (-) or from negative (-) to positive (+), and may mean a point where the gradient value is 0. In addition, the critical point of the sixteenth surface (S16) may be a point where the gradient value of a tangent passing through the lens surface increases and then decreases, or a point where the gradient value decreases and then increases.

[0421]

[0422] LensSurfaceRadiusThicknessndvdSemiApertureFocal length1S162.6861.0001.69453.2015.144-7.194 S24.6012.744 3.829 2S1-25.2823.9981.94617.9423.78625.219 S2-13.1000.860 3.930 STOP(STOP) Infinity0.600 3.593 3S113.5573.0771.43795.1003.78611.706 S2-7.6940.587 3.830 4S1-12.6021.0001.61425.5803.770-13.977 S228.3780.405 4.267 5S114.3022.9421.53655.9814.88117.407 S2-25.2090.200 4.973 6S19.6883.0001.53655.9815.07613.411 S2-25.2560.148 5.042 7S127.1141.2001.61425.5804.745-17.301 S27.5442.097 4.300 8S16.7401.8751.53655.9814.44998.667 S26.9690.767 5.000 FilterS1Infinity0.900 5.020 S2Infinity2.498 5.042 ImageImageInfinity0.002 5.143

[0423] Table 5 shows the surface number (Surface), radius of curvature (Radius), center thickness of each lens or distance between lens surfaces (Thickness), refractive index (Index,nd), Abbe number (Abbe,vd), effective radius (Semi Aperture), and focal length (Fcoal length) of the lens according to the third embodiment of the present invention. At this time, the unit of the radius of curvature and thickness or distance may be mm.

[0424] Item ValueItem ValueF6.210ET12.924ΣIndex12.914ET22.693ΣAbbe385.345ET31.494ΣCT18.703ET41.992ΣCG7.041ET51.482CA_max10.288ET61.469CA_min7.186ET72.2 96CA_Aver8.660ET82.074CT_max3.998F-number1.650CT_min1.000HFOV106.000CT_Aver2.338ImgH10.286EPD3.764SD17.898BFL4.167TTL29.900TD26.500

[0425] Table 6 shows the items of the mathematical formulas described above in the optical system (1200) of the embodiment, including the total track length (TTL) (mm), back focal length (BFL), effective focal length (F) (mm), ImgH (mm), effective diameter (CA) (mm), thickness (mm), TTL (mm), the optical axis distance from the first surface (S1) to the eighth surface (S8) TD (mm), the optical axis distance from the stop (Stop) to the eighth surface (S8) SD (mm), the sum of refractive indices, the sum of Abbe numbers, the sum of thicknesses (mm), the sum of spacings between adjacent lenses, effective diameter characteristics, horizontal field of view (HFOV) (Degree), edge thickness (ET), F number, etc. of the optical system (1200).

[0426] The center thicknesses of the first to eighth lenses (301 to 308) are represented by CT1 to CT8, the edge thicknesses at the ends of the effective areas of each lens are represented by ET1 to ET8, the center gap between two adjacent lenses is represented by CG1 to CG7, and the edge gaps between the edges of each lens are represented by EG1 to EG8. The back focal length (BFL) is the optical axis distance from the image sensor (400) to the center of the last lens. The TTL is the optical axis distance from the center of the first surface (S1) of the first lens (301) to the upper surface of the image sensor (400).

[0427] As shown in FIG. 14, among the lenses of the lens unit of the third embodiment, the lens surfaces of the first lens (301), the fourth lens (304), the fifth lens (305), the sixth lens (306), the seventh lens (307), and the eighth lens (308) may include aspherical surfaces having a 30th-order aspherical coefficient. For example, the first lens (301), the fourth lens (304), the fifth lens (305), the sixth lens (306), the seventh lens (307), and the eighth lens (308) may include lens surfaces having a 30th-order aspherical coefficient. As described above, the aspherical surface having a 30th-order aspherical coefficient (a value other than "0") can significantly change the aspherical shape of the periphery, and thus can effectively correct the optical performance of the periphery of the field of view (FOV).

[0428] When comparing the absolute values ​​of the curvature radii of each lens, the curvature radii of the first surface (S1) of the first lens (301) on the optical axis (OA) may be the largest among the lenses, and the curvature radii of the second surface (S2) of the first lens (301) may be the smallest among the lenses. The difference between the maximum curvature radii and the minimum curvature radii may be 10 times or more, for example, 10 to 15 times. The curvature radii of the sensor-side surface of the first lens (301) arranged on the object side of the second lens (302) may be the smallest among the lenses.

[0429] In temperature-compensated designs that require maintaining resolution across temperatures ranging from -40 to 100 degrees Celsius, a larger radius of curvature can be advantageous. Aluminum lens barrels can be used for temperature compensation. Aluminum barrels have large manufacturing tolerances, which can significantly misalign the optical axes of individual lenses during assembly. Therefore, a larger radius of curvature can be used to reduce sensitivity to manufacturing tolerances.

[0430] The fourth to eighth lenses (304 to 308) having aspherical shapes can be designed to have gentle shapes. If the aspherical surface is positioned at the frontmost position in the optical system (1200), the performance of the lens is improved, but the assemblability may be reduced. To improve the assemblability, the shapes of the fourth to eighth lenses (304 to 308) should be designed to have gentle shapes. In order to minimize the influence on the lens positioned on the sensor side when assembling the lens in the barrel, the lenses can be designed to have almost no curvature.

[0431] Both the object-side and sensor-side surfaces of the seventh lens (307) and the eighth lens (308) may include inflection points and may have a gull-shaped shape (a shape including both concave and convex shapes). Accordingly, when a lens positioned adjacent to the image sensor (400) has an inflection point, the performance of aberrations (e.g., distortion aberration, coma aberration in the peripheral field, etc.) relative to the axis may be improved.

[0432] The second lens (302) may have a meniscus shape toward the sensor side, and the third lens (303) may have a biconvex shape. Since the third lens (302) has a meniscus shape, the effective diameter of the first lens (301) is reduced, and since the third lens (303) has a biconvex shape made of glass, temperature compensation is easy and aberration correction is effective. In order to correct aberration and form an appropriate focal length, the lens arranged adjacent to the aperture (STOP) may have a biconvex shape. For example, the third lens arranged on the sensor side of the aperture (STOP) may have a biconvex shape.

[0433] The absolute value of the curvature radius of the first surface (S1) of the first lens (301) may be greater than the absolute value of the curvature radius of the second surface (S2). The absolute value of the curvature radius of the third surface (S3) of the second lens (302) may be greater than the absolute value of the curvature radius of the fourth surface (S4). The absolute value of the curvature radius of the fifth surface (S5) of the third lens (303) may be greater than the absolute value of the curvature radius of the sixth surface (S6). The absolute value of the curvature radius of the seventh surface (S7) of the fourth lens (304) may be less than the absolute value of the curvature radius of the eighth surface (S8). The absolute value of the curvature radius of the ninth surface (S9) of the fifth lens (305) may be less than the absolute value of the curvature radius of the tenth surface (S10). The absolute value of the curvature radius of the eleventh surface (S11) of the sixth lens (306) may be smaller than the absolute value of the curvature radius of the twelfth surface (S12). The absolute value of the curvature radius of the thirteenth surface (S13) of the seventh lens (307) may be larger than the absolute value of the curvature radius of the fourteenth surface (S14). The absolute value of the curvature radius of the fifteenth surface (S15) of the eighth lens (308) may be smaller than the absolute value of the curvature radius of the sixteenth surface (S16).

[0434] When the curvature radius of the object-side surface and the sensor-side surface of the first lens (301) satisfy condition 1 below, the object-side surface of the first lens (301) can be formed into a shape close to a plane, so that the refractive power of the first lens (301) can be designed to be large, and the curvature of the sensor-side surface of the first lens (301) can be designed to be small, so that an appropriate angle of view can be set for the optical system.

[0435] The ratio of the radius of curvature of each lens can satisfy the following conditions.

[0436] Condition 1: 10 < |L1R1 / L1R2| < 15

[0437] Condition 2: 1.5 < |L2R1 / L2R2| < 2

[0438] Condition 3: 1.5 < |L3R1 / L3R2| < 2

[0439] Condition 4: 0.1 < |L4R1 / L4R2| < 0.5

[0440] Condition 5: 0.5 < |L5R1 / L5R2| < 1

[0441] Condition 6: 0.1 < |L6R1 / L6R2| < 0.5

[0442] Condition 7: 3 < |L7R1 / L7R2| < 5

[0443] Condition 8: 0.5 < |L8R1 / L8R2| < 1

[0444]

[0445] When describing the central thickness of the lenses based on the optical axis, the central thickness (CT2) of the second lens (302) is the largest among the lenses, and the central thicknesses (CT1, CT4) of the first lens (301) and the fourth lens (304) are the smallest among the lenses. The difference between the maximum central thickness and the minimum central thickness among the lenses may be in the range of 2 mm or more and 3 mm or less.

[0446] The central thickness of each lens may satisfy any one of the following conditions:

[0447] Condition 1: CT2, CT3, CT5, CT6, CT7, CT8 > CT1 = CT4

[0448] Condition 2: CT2 > CT1, CT3, CT4, CT5, CT6, CT7, CT8

[0449] Condition 3: CT2 > CT3 > CT1, CT4, CT5, CT6, CT7, CT8

[0450] Condition 4: CT2, CT3, CT6 > CT5 > CT1, CT4, CT7, CT8

[0451] Condition 5: CT2, CT3 > CT6 > CT1, CT4, CT5, CT7, CT8

[0452] Condition 6: CT2, CT3, CT5, CT6, CT8 > CT7 > CT1, CT4

[0453] Condition 7: CT2, CT3, CT5, CT6 > CT8 > CT1, CT4, CT7

[0454]

[0455] When describing the center spacing (CG) between the lenses, the center spacing (CG1) between the first lens (301) and the second lens (302) may be the maximum, and the center spacing (CG6) between the sixth and seventh lenses (306, 307) may be the minimum. The difference between the maximum center spacing and the minimum center spacing among the spaced lens spacings may be 2 mm or more, for example, in the range of 2.5 mm to 3.0 mm.

[0456] The center spacing between each lens can satisfy the conditions below.

[0457] Condition 1: CG1 > CG2, CG3, CG4, CG5, CG6, CG7

[0458] Condition 2: CG1, CG7 > CG2 > CG3, CG4, CG5, CG6

[0459] Condition 3: CG1, CG2, CG7 > CG3 > CG4, CG5, CG6

[0460] Condition 4: CG1, CG2, CG3, CG7 > CG4 > CG5, CG6

[0461] Condition 5: CG1, CG2, CG3, CG4, CG7 > CG5 > CG6

[0462] Condition 6: CG1, CG2, CG3, CG4, CG5, CG7 > CG6

[0463] Condition 7: CG1 > CG7 > CG2, CG3, CG4, CG5, CG6

[0464]

[0465] Regarding the effective diameter, the effective diameter of the sixth lens (306) is the maximum, and the lens with the maximum effective diameter may be a plastic lens. The lens with the maximum effective diameter may be the sixth lens (306). Here, the effective diameter is the average of the effective diameters of the object-side surface and the sensor-side surface of each lens. The lens surface with the maximum effective diameter may be the first surface (S1) of the first lens (301).

[0466] The lens having the minimum effective diameter may be any one of the glass material lenses, and for example, the effective diameter of the third lens (303) may be the minimum within the lens unit. The lens surface having the minimum effective diameter may be the seventh surface (S7) of the fourth lens (304).

[0467] The effective diameter may decrease from the first lens (301) to the second lens (303) and may increase from the fourth lens (304) to the fifth lens (305). Here, the effective diameter of each lens may mean the average of the effective diameter value of the object-side surface of the lens and the effective diameter value of the sensor-side surface of the lens. The average effective diameter value of the object-side and sensor-side surfaces of each lens may decrease from the first lens (301) to the second lens (302) and may increase from the fourth lens (304) to the fifth lens (305). The position of the aperture (STOP) having a small effective diameter is arranged on the sensor side of the second lens (303), and the position of the aperture (STOP) is relatively located on the object side rather than the sensor side, so that the effective diameter of the first lens (301) may decrease.

[0468] The average effective diameter of the object-side and sensor-side surfaces of each glass lens positioned closer to the object side than the plastic lens may be smaller than the average effective diameter of the object-side and sensor-side surfaces of each plastic lens. Alternatively, the effective diameter of the glass lens positioned on the object side of the plastic lens may have the smallest effective diameter in the optical system (1200). For example, when the fourth to eighth lenses (304 to 308) are made of plastic and the third lens (303) is made of glass, the average effective diameter of the object-side and sensor-side surfaces of the third lens (303) may be smaller than the average of the effective diameters of the object-side and sensor-side surfaces of the fourth to eighth lenses (304 to 308). In addition, the average effective diameter of the object-side and sensor-side surfaces of the third lens (303) may have the smallest effective diameter in the optical system (1200). Among the first to eighth lenses (301-308), a plurality of lenses sequentially arranged may be made of glass, and the remaining lenses sequentially arranged may be made of plastic. Among the first to eighth lenses (301-308), the effective diameter of the glass lens arranged closest to the lens made of plastic may be the smallest.

[0469] In relation to the above, an inner barrel may be additionally positioned between the plastic lens and the glass lens to minimize changes in optical performance due to changes in the shape of the plastic lens that expands at high temperatures. Alternatively, a partition wall protruding into the lens barrel may be formed between the plastic lens and the glass lens to prevent interference due to the high-temperature expansion of the plastic lens.

[0470] The effective diameter of each lens can satisfy any one of the conditions below.

[0471] Condition 1: CA_L5, CA_L6, CA_L7, CA_L8 > CA_L1 > CA_L2, CA_L3, CA_L4

[0472] Condition 2: CA_L1, CA_L4, CA_L5, CA_L6, CA_L7, CA_L8 > CA_L2 > CA_L3

[0473] Condition 3: CA_L1, CA_L2, CA_L4, CA_L5, CA_L6, CA_L7, CA_L8 > CA_L3

[0474] Condition 4: CA_L1, CA_L5, CA_L6, CA_L7, CA_L8 > CA_L4 > CA_L2, CA_L3

[0475] Condition 5: CA_L6 > CA_L5 > CA_L1, CA_L2, CA_L3, CA_L4, CA_L7, CA_L8

[0476] Condition 6: CA_L6 > CA_L1, CA_L2, CA_L3, CA_L4, CA_L5, CA_L7, CA_L8

[0477] Condition 7: CA_L5, CA_L6, CA_L8 > CA_L7 > CA_L1, CA_L2, CA_L3, CA_L4

[0478] Condition 8: CA_L5, CA_L6 > CA_L8 > CA_L1, CA_L2, CA_L3, CA_L4, CA_L7

[0479]

[0480] Regarding the refractive index, the refractive index of the second lens (302) may be the highest among the lenses and may be greater than 1.8, for example, greater than 1.9. The third lens (303) may have the lowest refractive index among the lenses. For example, the refractive index of the third lens (303) may be the lowest among the lenses and may be less than 1.5, for example, less than 1.45. The difference between the maximum refractive index and the minimum refractive index may be 0.4 or more.

[0481] The refractive index of each lens can satisfy any of the conditions below.

[0482] Condition 1: n2 > n1 > n3, n4, n5, n6, n7, n8

[0483] Condition 2: n2 > n1, n3, n4, n5, n6, n7, n8

[0484] Condition 3: n1, n2, n4, n5, n6, n7, n8 > n3

[0485] Condition 4: n1, n2 > n4 = n7 > n3, n5, n6, n8

[0486] Condition 5: n1, n2, n4, n7 > n5 = n6 = n8 > n3

[0487]

[0488] Comparing the Abbe numbers, the Abbe number of the third lens (303) is the largest among the lenses and may be 90 or greater. The Abbe number of the second lens (302) is the smallest among the lenses and may be 20 or less. The difference between the maximum Abbe number and the minimum Abbe number may be 70 or greater.

[0489] The Abbe number of each lens can satisfy any of the conditions below.

[0490] Condition 1: v3, v5, v6, v8 > v1 > v2, v4, v7

[0491] Condition 2: v1, v3, v4, v5, v6, v7, v8 > v2

[0492] Condition 3: v3 > v1, v2, v4, v5, v6, v7, v8

[0493] Condition 4: v1, v3, v5, v6, v8 > v4 = v7 > v2

[0494] Condition 5: v3 > v5 = v6 = v8 > v1, v2, v4, v7

[0495]

[0496] The focal lengths (F2, F3, F5, F6, F8) of the second, third, fifth, sixth, and eighth lenses (302, 303, 305, 306, and 308) may have positive (+) signs. The second, third, fifth, sixth, and eighth lenses (302, 303, 305, 306, and 308) may have positive (+) refractive power. The focal lengths (F1, F4, and F7) of the first, fourth, and seventh lenses (301, 304, and 307) may have negative (-) signs. The first, fourth, and seventh lenses (301, 304, and 307) may have negative (-) refractive power. A fourth lens (304) having negative (-) refractive power may be arranged on the sensor side of the third lens (303) having positive (+) refractive power. Through this, light incident from the object side can gather in the direction of the optical axis and then move away from the direction of the optical axis, thereby forming a stable optical path.

[0497]

[0498] When comparing the focal lengths in absolute values, the focal length of the eighth lens (308) is the largest among the lenses, and may be 80 or more and 100 or less. Among the lenses, the eighth lens (308) made of plastic may have the largest focal length and the smallest refractive power. The focal length of the first lens (301) is the smallest among the lenses, and the absolute value of the focal length of the first lens (301) may be 5 or more and 10 or less. Among the lenses, the first lens (301) made of glass may have the smallest focal length and the largest refractive power.

[0499] Among the lenses, the lens having the minimum focal length may be the first lens (301). The difference between the maximum focal length and the minimum focal length may be 80 or more or 100 or more. Accordingly, the optical system may have improved MTF characteristics, aberration control characteristics, resolution characteristics, etc. in the set field of view range, and may have good optical performance in the periphery of the field of view.

[0500] The absolute value of the focal length of each lens can satisfy any of the conditions below.

[0501] Condition 1: |f2|, |f3|, |f4|, |f5|, |f6|, |f7|, |f8| > |f1|

[0502] Condition 2: |f8| > |f2| > |f1|, |f3|, |f4|, |f5|, |f6|, |f7|

[0503] Condition 3: |f2|, |f4|, |f5|, |f6|, |f7|, |f8| > |f3| > |f1|

[0504] Condition 4: |f2|, |f5|, |f7|, |f8| > |f4| > |f1|, |f3|, |f6|

[0505] Condition 5: |f2|, |f8| > |f5| > |f1|, |f3|, |f4|, |f6|, |f7|

[0506] Condition 6: |f2|, |f4|, |f5|, |f7|, |f8| > |f6| > |f1|, |f3|

[0507] Condition 7: |f2|, |f5|, |f8| > |f7| > |f1|, |f3|, |f4|, |f6|

[0508] Condition 8: |f8| > |f1|, |f2|, |f3|, |f4|, |f5|, |f6|, |f7|

[0509]

[0510] The thickness (T1) of the first lens (301) may be maximum at the edge and minimum at the center, and the maximum thickness is in the range of 2.5 to 3 times the minimum thickness. The thickness (T2) of the second lens (302) may be minimum at the edge and maximum at the center, and the maximum thickness is in the range of 1 to 1.5 times the minimum thickness. The thickness (T3) of the third lens (303) may be maximum at the center and minimum at the edge, and the maximum thickness is in the range of 2 to 2.5 times the minimum thickness. The thickness (T4) of the fourth lens (304) may be minimum at the center and maximum at the edge, and the maximum thickness is in the range of 1.5 to 2 times the minimum thickness. The thickness (T5) of the fifth lens (305) may be maximum at the center and minimum at the edge, and the maximum thickness is in the range of 1.5 to 2 times the minimum thickness. The thickness (T6) of the sixth lens (306) may be maximum at the center and minimum at the edge, and the maximum thickness is in the range of 2 to 2.5 times the minimum thickness. The thickness (T7) of the seventh lens (307) may be minimum at the center and maximum at the edge, and the maximum thickness is in the range of 1.5 to 2 times the minimum thickness. The thickness (T8) of the eighth lens (308) may be maximum at the center and minimum at the edge, and the maximum thickness is in the range of 1 to 1.5 times the minimum thickness.

[0511] The thickness of each lens can satisfy any of the conditions below.

[0512] Condition 1: 0.1 < CT1 / ET1 < 0.5, 2.5 < ET1 / CT1 < 3

[0513] Condition 2: 1 < CT2 / ET2 < 1.5, 0.5 < ET2 / CT2 < 1

[0514] Condition 3: 2 < CT3 / ET3 < 2.5, 0.1 < ET3 / CT3 < 0.5

[0515] Condition 4: 0.5 < CT4 / ET4 < 1, 1.5 < ET4 / CT4 < 2

[0516] Condition 5: 1.5 < CT5 / ET5 < 2, 0.5 < ET5 / CT5 < 1

[0517] Condition 6: 2 < CT6 / ET6 < 2.5, 0.1 < ET6 / CT6 < 0.5

[0518] Condition 7: 0.5 < CT7 / ET7 < 1, 1.5 < ET7 / CT7 < 2

[0519] Condition 8: 1 < CT8 / ET8 < 1.5, 0.5 < ET8 / CT8 < 1

[0520] Condition 9: 1 < ΣCT / ΣET < 1.5, 0.5 < ΣET / ΣCT < 1

[0521]

[0522] Among the gaps (G1-G7) between the lenses, the first gap (G1) between the first and second lenses (301, 302) may have a maximum in the center and a minimum in the edge. The second gap (G2) between the second and third lenses (302, 303) may have a minimum in the center and a maximum in the edge. The third gap (G3) between the third and fourth lenses (303, 304) may have a maximum in the edge and a minimum in the center. The fourth gap (G4) between the fourth and fifth lenses (304, 305) may have a maximum in the edge and a minimum in the center. The fifth gap (G5) between the fifth and sixth lenses (305, 306) may have a maximum in the edge and a minimum in the center. The sixth gap (G6) between the sixth and seventh lenses (306, 307) may have a maximum in the edge and a minimum in the center. The seventh gap (G7) between the seventh and eighth lenses (307, 308) may be minimum at the edge and maximum at the center.

[0523]

[0524] FIGS. 16, 17, and 18 are graphs showing the diffraction MTF (Modulation Transfer Function) at room temperature, low temperature, and high temperature in the optical system of FIG. 13, and are graphs showing the modulation ratio according to spatial frequency. As shown in FIGS. 16, 17, and 18, in the third embodiment of the invention, the deviation of the MTF at low temperature or high temperature based on room temperature may be less than 10%, that is, 7% or less.

[0525] Fig. 19 is a graph showing the aberration characteristics at room temperature in the optical system of Fig. 13. In the aberration graph of Fig. 19, spherical aberration (longitudinal spherical aberration), astigmatic field curves, and distortion are measured from left to right. In Fig. 19, 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. In addition, the graph for spherical aberration is a graph for light in wavelength bands of about 435 nm, about 486 nm, about 546 nm, about 587 nm, and about 656 nm, and the graphs for astigmatism and distortion are graphs for light in wavelength bands of about 546 nm. In the aberration diagram of Fig. 19, the closer each curve at room temperature is to the Y-axis, the better the aberration correction function can be interpreted. In the optical system (1200) according to the third embodiment, it can be seen that the measured values ​​are close to the Y-axis in almost all areas. That is, the optical system (1200) according to the third embodiment 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. Here, the room temperature can be in the range of 22 degrees ± 5 degrees or in the range of 18 degrees to 27 degrees.

[0526] The optical system of the third embodiment disclosed above can effectively control aberration characteristics such as chromatic aberration and distortion aberration, and can have good optical performance not only at the center of the field of view (FOV) but also at the periphery.

[0527]

[0528] The optical systems (1000, 1100, 1200) according to the first to third embodiments disclosed above can satisfy at least one or two or more of the mathematical equations described below. Accordingly, the optical systems (1000, 1100, 1200) according to the first to third embodiments can have improved optical characteristics. For example, when the optical systems (1000, 1100, 1200) satisfy at least one mathematical equation, the optical systems (1000, 1100, 1200) can effectively control aberration characteristics such as chromatic aberration and distortion aberration, and can have good optical performance not only at the center of the field of view (FOV) but also at the periphery. In addition, the optical systems (1000, 1100, 1200) can have improved resolution. In addition, the thickness of the lens on the optical axis (OA) and the spacing between adjacent lenses on the optical axis (OA) described in the mathematical formulas may refer to the first to third embodiments disclosed above.

[0529]

[0530] The optical systems (1000, 1100, 1200) according to the first to third embodiments disclosed above can satisfy at least one or two or more of the mathematical equations described below. Accordingly, the optical systems (1000, 1100, 1200) according to the first to third embodiments can have improved optical characteristics. For example, when the optical systems (1000, 1100, 1200) satisfy at least one mathematical equation, the optical systems (1000, 1100, 1200) can effectively control aberration characteristics such as chromatic aberration and distortion aberration, and can have good optical performance not only at the center of the field of view (FOV) but also at the periphery. In addition, the optical systems (1000, 1100, 1200) can have improved resolution. In addition, the thickness of the lens on the optical axis (OA) and the spacing between adjacent lenses on the optical axis (OA) described in the mathematical formulas may refer to the first to third embodiments disclosed above.

[0531]

[0532] [Mathematical Formula 1]

[0533] 0.4 < n2-n3 < 0.6

[0534] In mathematical expression 1, n2 is the refractive index of the second lens (102, 202, 302), and n3 is the refractive index of the third lens (103, 303, 303). When mathematical expression 1 is satisfied, chromatic aberration occurring in the optical path within the optical system can be reduced. Since the range of the refractive index of plastic materials is limited, it is advantageous to reduce chromatic aberration in a lens made of glass. When it is below the lower limit of mathematical expression 1, the light passing through the lens cannot be properly refracted, which may deteriorate optical performance. When it exceeds the upper limit of mathematical expression 1, since the lens must be formed of a special material, there is a problem that the manufacturing cost increases during mass production. In the first to third embodiments, mathematical expression 1 can satisfy 0.45 < n2-n3 < 0.55.

[0535]

[0536] [Equation 2]

[0537] 20 < |L2R1| < 110

[0538] In mathematical expression 2, |L2R1| is the absolute value of the curvature radius of the object-side surface of the second lens (102, 202, 302). If mathematical expression 2 is satisfied, UV coating can be easily applied to the object-side surface of the second lens (102, 202, 302). If it is less than the lower limit of mathematical expression 2, the curvature of the object-side surface of the second lens (102, 202, 302) is designed to be large, making coating difficult. If it is more than the upper limit of mathematical expression 2, it can be difficult to appropriately set the light path incident in the entire optical system. In the first to third embodiments, mathematical expression 2 can satisfy 24 < |L2R1| < 105.

[0539]

[0540] [Equation 3]

[0541] L3R1 > 0, L3R2 < 0, 1.4 < n3 < 1.6

[0542] In mathematical expression 3, L3R1 is the radius of curvature of the object-side surface of the third lens (103, 203, 303), L3R2 is the radius of curvature of the sensor-side surface of the third lens (103, 203, 303), and n3 is the refractive index of the third lens (103, 203, 303). L3R1 > 0 means that the object-side surface of the third lens (103, 203, 303) is convex toward the object side on the optical axis, and L3R2 < 0 means that the sensor-side surface of the third lens (103, 203, 303) is convex toward the sensor side on the optical axis. When mathematical expression 3 is satisfied, by arranging a lens having a biconvex shape among the glass lenses, the optical path of light incident on the optical system can be set, and good optical performance can be achieved at the set angle of view and focal length.

[0543]

[0544] [Equation 4]

[0545] 1 < |F1| / F < 2

[0546] In mathematical expression 4, F1 is the focal length of the first lens (101, 201, 301), and F is the effective focal length of the optical system. When mathematical expression 4 is satisfied, the optical system (1000, 1100, 1200) can have a set angle of view and an appropriate focal length, and an optical system for a vehicle can be provided. In addition, the angle of view can be set to be large in an appropriate TTL range through the first lens (101, 201, 301) having negative (-) refractive power. When it is below the lower limit of mathematical expression 4, the effective diameter or TTL of the lenses may become long, which may cause a problem in that the imaging lens system becomes large. When it is above the upper limit of mathematical expression 4, the influence of the first lens (101, 201, 301) in the entire optical system becomes small, and the refractive power of the lenses needs to be increased, which causes a problem in that it is difficult to correct spherical aberration or distortion aberration. In the first to third embodiments, mathematical expression 4 preferably satisfies 1 < |F1| / F < 1.5.

[0547]

[0548] [Equation 5]

[0549] 1.8 < n2 < 2

[0550] In mathematical expression 5, n2 is the refractive index of the second lens (102, 202, 302). When mathematical expression 5 is satisfied, the second lens (102, 202, 302) can minimize chromatic aberration by having a high refractive index among glass lenses. In the first to third embodiments, mathematical expression 5 can preferably satisfy 1.9 < n2 < 2.

[0551]

[0552] [Equation 6]

[0553] 15 < v2 < 25

[0554] In mathematical expression 6, v2 is the Abbe number of the second lens (102, 202, 302). When mathematical expression 6 is satisfied, the second lens (102, 202, 302) can minimize chromatic aberration by having a high Abbe number among glass lenses. In the first to third embodiments, mathematical expression 6 can preferably satisfy 17 < v2 < 21.

[0555]

[0556] [Equation 7]

[0557] 90 < v3 < 100

[0558] In mathematical expression 7, v3 is the Abbe number of the third lens (103, 203, 303). When mathematical expression 7 is satisfied, the third lens (103, 203, 303) can minimize chromatic aberration by having a high Abbe number among glass lenses. In the first to third embodiments, mathematical expression 7 can preferably satisfy 93 < v3 < 96.

[0559]

[0560] [Equation 8]

[0561] 1.5 < F3 / F < 2

[0562] In mathematical expression 8, F3 is the focal length of the third lens (103, 203, 303), and F is the effective focal length of the optical system. When mathematical expression 8 is satisfied, the optical system (1000, 1100, 1200) can have a set angle of view and an appropriate focal length, and a vehicle optical system can be provided. When it is below the lower limit of mathematical expression 8, the effective diameter or TTL of the lenses may become long, which may cause a problem of the large size of the imaging lens system. When it is above the upper limit of mathematical expression 8, the influence of the third lens (103, 203, 303) in the entire optical system becomes small, and the refractive power of the lenses needs to be increased, which causes a problem of difficulty in correcting spherical aberration or distortion aberration. In the first to third embodiments, mathematical expression 8 may preferably satisfy 1.6 < F3 / F < 1.9.

[0563]

[0564] [Equation 9]

[0565] 2 < |F7| / F < 3

[0566] In mathematical expression 9, F7 is the focal length of the seventh lens (107, 207, 307), and F is the effective focal length of the optical system. When mathematical expression 9 is satisfied, the optical system (1000, 1100, 1200) can have a set angle of view and an appropriate focal length, and a vehicle optical system can be provided. When it is less than the lower limit of mathematical expression 9, the effective diameter or TTL of the lenses may become long, which may cause a problem of the large size of the imaging lens system. When it is more than the upper limit of mathematical expression 9, the influence of the seventh lens (107, 207, 307) in the entire optical system becomes small, and the refractive power of the lenses needs to be increased, which causes a problem of difficulty in correcting spherical aberration or distortion aberration. In the first to third embodiments, mathematical expression 9 may preferably satisfy 2.3 < |F7| / F < 3.

[0567]

[0568] [Equation 10]

[0569] 5 < F8 / F < 17

[0570] In mathematical expression 10, F8 is the focal length of the eighth lens (108, 208, 308), and F is the effective focal length of the optical system. When mathematical expression 10 is satisfied, the optical system (1000, 1100, 1200) can have a set angle of view and an appropriate focal length, and a vehicle optical system can be provided. When it is less than the lower limit of mathematical expression 10, the effective diameter or TTL of the lenses may become long, which may cause a problem of the large size of the imaging lens system. When it is more than the upper limit of mathematical expression 10, the influence of the eighth lens (108, 208, 308) in the entire optical system becomes small, and the refractive power of the lenses needs to be increased, which causes a problem of difficulty in correcting spherical aberration or distortion aberration. In the first embodiment, mathematical expression 10 may preferably satisfy 5 < |F8| / F < 6. In the second embodiment, mathematical expression 10 can preferably satisfy 7 < |F8| / F < 8. In the third embodiment, mathematical expression 10 can preferably satisfy 15 < |F8| / F < 16.

[0571]

[0572] [Equation 11]

[0573] 0.4 < n_max-n_min < 0.6

[0574] In mathematical expression 11, n_max is the refractive index of the lens with the highest refractive index in the optical system, and n_min is the refractive index of the lens with the lowest refractive index in the optical system. When mathematical expression 11 is satisfied, the optical path can be appropriately set within the optical system, and the imaging lens system can be miniaturized. Specifically, in the first to third embodiments, the lenses with the highest refractive index and the lenses with the lowest refractive index can be arranged most closely together, and the lenses with the highest and lowest refractive indices can be made of glass. Since the range of refractive indices of plastic materials is limited, it is advantageous to reduce chromatic aberration in lenses made of glass. When n_max is less than the lower limit of mathematical expression 11, the optical performance may deteriorate because the light passing through the lens cannot be appropriately refracted. When n_min is greater than the upper limit of mathematical expression 11, the lens must be formed of a special material, which increases the manufacturing cost during mass production. In the first to third embodiments, mathematical expression 11 can satisfy 0.45 < n_max-n_min < 0.55.

[0575]

[0576] [Equation 12]

[0577] 0.1 < F / TTL < 0.5

[0578] In mathematical expression 12, F is the effective focal length of the optical system, and TTL (Total track length) means the distance (mm) on the optical axis (OA) from the vertex of the first surface (S1) of the first lens (101, 201, 301) to the upper surface of the image sensor (400). Accordingly, an optical system for a driver assistance system can be provided. When mathematical expression 12 is satisfied, the optical system (1000, 1100, 1200) can have an appropriate focal length in the set TTL range, and provides an optical system that can form an image while maintaining an appropriate focal length even when the temperature changes from low to high temperature. When it is less than the lower limit of mathematical expression 12, the refractive power of the lenses needs to be increased, making it difficult to correct spherical aberration or distortion aberration, and when it exceeds the upper limit of mathematical expression 12, the effective diameter or TTL of the lenses may become long, which may cause a problem in that the imaging lens system becomes large. In the first to third embodiments, mathematical expression 12 can preferably satisfy 0.1 < F / TTL < 0.3.

[0579]

[0580] [Equation 13]

[0581] 2 < TTL / ImgH < 3

[0582] Mathematical expression 13 is TTL (Total track length), which means the distance (mm) from the vertex of the first surface (S1) of the first lens (101, 201, 301) to the upper surface of the image sensor (400) on the optical axis (OA), and ImgH means the maximum diagonal length of the image sensor (400). When Mathematical expression 13 is satisfied, the optical system (1000, 1100, 1200) can have TTL for application to the vehicle image sensor (400), and can provide more improved image quality. When it is less than the lower limit of Mathematical expression 13, the refractive power of the lenses needs to be increased, making it difficult to correct spherical aberration or distortion aberration, and when it is more than the upper limit of Mathematical expression 13, the effective diameter or TTL of the lenses becomes long, which may cause a problem of the imaging lens system becoming larger. In the first to third embodiments, mathematical expression 13 can preferably satisfy 2.5 < TTL / ImgH < 3.

[0583]

[0584] [Equation 14]

[0585] 5 < (F2 / F) + (F3 / F) < 6

[0586] In mathematical expression 14, F2 is the focal length of the second lens (102, 202, 302), F3 is the focal length of the third lens (103, 203, 303), and F is the effective focal length of the optical system. When mathematical expression 14 is satisfied, an optical system capable of forming an image while maintaining an appropriate focal length even when the temperature changes from low to high temperature is provided. When it is below the lower limit of mathematical expression 14, there is a problem that it is difficult to correct spherical aberration or distortion aberration because an appropriate optical path cannot be formed. When it exceeds the upper limit of mathematical expression 14, the temperature compensation effect of the optical performance of the optical system may be minimal. In the first to third embodiments, mathematical expression 14 may preferably satisfy 5.1 < (F2 / F) + (F3 / F) < 6.

[0587]

[0588] [Equation 15]

[0589] 1 < CT_Max / CG_Max < 2

[0590] In Equation 15, CT_Max is the maximum central thickness among the lenses, and CG_Max is the maximum gap between adjacent lenses. When Equation 15 is satisfied, the optical system can have good optical performance at a focal length at a set angle of view, and can reduce TTL. In the first to third embodiments, Equation 15 preferably satisfies 1 < CT_Max / CG_Max < 1.5.

[0591]

[0592] [Equation 16]

[0593] 1 < CA_max / CA_min < 2

[0594] In mathematical expression 16, CA_max represents the maximum effective diameter among the object-side and sensor-side surfaces of the lenses, and CA_Min represents the minimum effective diameter among the object-side and sensor-side surfaces of the lenses. When mathematical expression 16 is satisfied, the optical system can set a size for a slim and compact structure while maintaining optical performance. In the first to third embodiments, mathematical expression 16 can preferably satisfy 1.3 < CA_max / CA_min < 1.6.

[0595]

[0596] [Equation 17]

[0597] 0.1 < ΣCG / ΣCT < 0.5

[0598] In mathematical expression 17, ΣCT is the sum of the central thicknesses of the lenses, and ΣCG is the sum of the spacings between adjacent lenses. When mathematical expression 17 is satisfied, the optical system can have good optical performance at the focal length at the set angle of view, and can reduce the TTL. In the first to third embodiments, mathematical expression 17 can preferably satisfy 0.3 < ΣCG / ΣCT < 0.5.

[0599]

[0600] [Equation 18]

[0601] 1.5 < F / EPD < 2

[0602] In mathematical expression 18, F represents the effective focal length of the optical system, and EPD represents the diameter of the entrance pupil (effective aperture). When mathematical expression 18 is satisfied, an image with a brightness suitable for driver monitoring can be provided, and a large amount of light can be received by the image sensor. In the first to third embodiments, mathematical expression 18 preferably satisfies 1.5 < F / EPD < 1.7.

[0603]

[0604] [Equation 19]

[0605] 0.1 < BFL / TTL < 0.5

[0606] In mathematical expression 19, BFL means the optical axis distance from the image sensor (400) to the center of the sensor side of the last lens, and TTL (Total track length) means the distance (mm) on the optical axis (OA) from the vertex of the first surface (S1) of the first lens (101, 201, 301) to the upper surface of the image sensor (400). When mathematical expression 19 is satisfied, the optical system (1000, 1100, 1200) can have a set angle of view and an appropriate focal length, and a vehicle optical system can be provided. In addition, the optical system (1000, 1100, 1200) can minimize the gap between the last lens and the image sensor (400), and thus can have good optical characteristics at the periphery of the field of view (FOV). In the first to third embodiments, mathematical expression 19 can preferably satisfy 0.1 < BFL / TTL < 0.3.

[0607]

[0608] [Equation 20]

[0609] 0.1 < CG1 / ΣCG < 0.5

[0610] In mathematical expression 20, CG1 is the center spacing between the first lens (101, 201, 301) and the second lens (102, 202, 302), and ΣCG is the sum of the spacings between adjacent lenses. When mathematical expression 20 is satisfied, the light emitted from the first lens (101, 201, 301), which has a large influence in the entire optical system, sets an optical path for entering the remaining lenses, and the optical system can have good optical performance at the set angle of view and focal length. In the first to third embodiments, mathematical expression 20 can preferably satisfy 0.3 < CG1 / ΣCG < 0.5.

[0611]

[0612] [Equation 21]

[0613] 0.1 < CG1 / ΣCT < 0.5

[0614] In mathematical expression 21, CG1 is the center spacing between the first lens (101, 201, 301) and the second lens (102, 202, 302), and ΣCT is the sum of the center thicknesses of the lenses. When mathematical expression 21 is satisfied, the light emitted from the first lens (101, 201, 301), which has a large influence in the entire optical system, sets an optical path for entering the remaining lenses, and the optical system can have good optical performance at the set angle of view and focal length. In the first to third embodiments, mathematical expression 21 can preferably satisfy 0.1 < CG1 / ΣCT < 0.3.

[0615]

[0616] [Equation 22]

[0617] 100 < HFOV < 120

[0618] In mathematical expression 22, HFOV represents the horizontal angle of view (Degree) of the optical system (1000, 1100, 1200), and can provide an angle of view suitable for a vehicle optical system. In the first to third embodiments, preferably, 100 < HFOV < 110 can be satisfied.

[0619]

[0620] [Equation 23]

[0621] 2.5 < TTL / CA_max < 3

[0622] In mathematical expression 23, TTL (Total track length) means the distance (mm) from the vertex of the first surface (S1) of the first lens (101, 201, 301) to the upper surface of the image sensor (400) on the optical axis (OA), and CA_max represents the maximum effective diameter among the object-side surfaces and the sensor-side surfaces of the lenses. When mathematical expression 23 is satisfied, the optical system can maintain good optical performance and set a size for a slim and compact structure. In the first to third embodiments, mathematical expression 23 can preferably satisfy 2.8 < TTL / CA_max < 3.

[0623]

[0624] [Equation 24]

[0625] 25 < TTL < 30

[0626] In mathematical expression 24, TTL (Total track length) means the distance (mm) from the center of the first surface (S1) of the first lens (101, 201, 301) to the upper surface of the image sensor (400) on the optical axis (OA). When mathematical expression 24 is satisfied, a suitable vehicle optical system can be provided. In the first to third embodiments, mathematical expression 24 can preferably satisfy 28 < TTL < 30.

[0627]

[0628] [Equation 25]

[0629] 9 < ImgH < 12

[0630] Mathematical expression 25 indicates that ImgH represents the maximum diagonal length of the image sensor (400). Mathematical expression 25 can set the diagonal size of the image sensor (400) and provide an optical system having a sensor size for a vehicle. In the first to third embodiments, Mathematical expression 25 can preferably satisfy 10 < ImgH < 10.5.

[0631]

[0632] [Equation 26]

[0633] 3 < BFL < 5

[0634] In mathematical expression 26, BFL is the optical axis distance from the image sensor (400) to the center of the sensor side of the last lens. When mathematical expression 26 is satisfied, the installation space of the filter (500) and the cover glass can be secured, the assembling of the components can be improved through the gap between the image sensor (400) and the last lens, and the joint reliability can be improved. When BFL is less than the range of mathematical expression 26, some of the light traveling to the image sensor cannot be transmitted to the image sensor, which may cause a decrease in resolution. When BFL exceeds the range of mathematical expression 26, stray light may be introduced, which may deteriorate the aberration characteristics of the optical system. In the first to third embodiments, mathematical expression 26 may preferably satisfy 4 < BFL < 5.

[0635]

[0636] [Equation 27]

[0637] 5 < F < 7

[0638] Mathematical expression 27 can set the overall focal length (F) to suit the vehicle optical system. In the first to third embodiments, Mathematical expression 27 can satisfy 6 < F < 6.5.

[0639]

[0640] [Equation 28]

[0641]

[0642] In mathematical expression 28, Z can 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 can represent the distance from any position on the aspherical surface to the optical axis in the direction perpendicular to the optical axis. c can represent the curvature of the lens, and K can represent the conic constant. In addition, A, B, C, D, E, and F can represent aspheric constants.

[0643]

[0644] The optical system (1000, 1100, 1200) according to the first to third embodiments may satisfy at least one or two or more mathematical expressions from mathematical expressions 1 to 28. In this case, the optical system (1000, 1100, 1200) may have improved optical characteristics. Specifically, when the optical system (1000, 1100, 1200) satisfies at least one or two or more mathematical expressions from mathematical expressions 1 to 28, the optical system (1000, 1100, 1200) may have improved resolution and may improve aberration and distortion characteristics. In addition, the optical system (1000, 1100, 1200) can secure a BFL (Back focal length) for applying a vehicle image sensor (400), compensate for the deterioration of optical characteristics due to temperature change, and minimize the gap between the last lens and the image sensor (400), thereby providing good optical performance in the center and periphery of the field of view (FOV).

[0645]

[0646] Table 7 shows the result values ​​for the mathematical expressions 1 to 27 described above in the optical system (1000, 1100, 1200) of the embodiment. Referring to Table 7, it can be seen that the optical system (1000, 1100, 1200) satisfies at least one, two or more, or three or more of the mathematical expressions 1 to 27. In detail, it can be seen that the optical system (1000, 1100, 1200) according to the embodiment satisfies all of the mathematical expressions 1 to 27. Accordingly, the optical system (1000, 1100, 1200) can have good optical performance and excellent optical characteristics at the center and periphery of the field of view (FOV).

[0647]

[0648] Mathematical expression Example 1 Example 2 Example 3 Example 10.4 < n2-n3 < 0.6 0.486 0.509 0.509 220 < |L2R1| < 1 10 10 4.86 53 0.46 82 5.28 23 L3R1 > 0 , L3R2 < 0, 1.4 < n3 < 1.6 Satisfied Satisfied Satisfied 41 < |F1| / F < 21.0471.0711.15851.8 < n2 < 21.9231.9461.946615 < v2 < 2520.88017.94217.942790 < v3 < 10095.10095.10095.10081.5 < F3 / F < 21.6671.7181.88592 < |F7| / F < 32.4052.9552.786105 < F8 / F < 175.1967.83315.888110.4 < n_max-n_min < 0.60.4860.5090.509120.1 < F / TTL < 0.50.2100.2070.208132 < TTL / ImgH < 32.8702.9162.907145 < (F2 / F) + (F3 / F) < 65.2905.5715.946151 < CT_Max / CG_Max < 21.1221.1691.457161 < CA_max / CA_min < 21.4791.4681.432170.1 < ΣCG / ΣCT < 0.50.4180.4710.434181.5 < F / EPD < 21.6501.6501.650190.1 < BFL / TTL < 0.50.1490.1470.139200.1 < CG1 / ΣCG < 0.50.4310.3800.390210.1 < CG1 / ΣCT < 0.50.1800.1790.16922100 < HFOV < 120102.000106.000106.000232.5 < TTL / CA_max < 32.9242.9272.9062425 < TTL < 3029.62429.99329.900259 < ImgH < 1210.32210.28610.286263 < BFL < 54.4244.3954.167275 < F < 76.2106.2106.210

[0649] Fig. 20 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. 20, 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, 25, 26), and a control unit (14). The image generating unit (11) may include at least one camera module (31) 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 (31), 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 first detection information.

[0650] 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. 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, 25, 26) detects each side of the own vehicle 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), and generates second detection information. Specifically, the second information generating unit (21, 22, 23, 24, 25, 26) 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, 25, 26) can be placed at the front two corners, side mirrors, and rear center and rear two corners of the vehicle, respectively.

[0651] At least one information generating unit of these vehicle camera systems may be equipped with an optical system and a camera module having the same as described in the embodiments disclosed above, 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.

[0652] The optical system of the camera module according to an embodiment of the invention can be installed in multiple units within a vehicle to enhance safety regulations, autonomous driving functions, and convenience. Furthermore, the optical system of the camera module is used as a component for controlling systems such as the Lane Keeping Assistance System (LKAS), Lane Departure Warning System (LDWS), and Driver Monitoring System (DMS). These vehicle camera modules can achieve stable optical performance even under ambient temperature changes and offer competitive pricing, thereby ensuring the reliability of vehicle components.

[0653]

[0654] 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.

[0655] 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

Including first to eighth lenses arranged along the optical axis, The above first lens has a negative (-) refractive power, The above second lens has positive (+) refractive power, The above third lens has positive (+) refractive power, The above fourth lens has a negative (-) refractive power, The above sixth lens has positive (+) refractive power, In the above optical axis, the second lens has a concave meniscus shape toward the sensor, An optical system in which the third lens has a convex shape on both sides of the optical axis. In the first paragraph, As you go from the first lens to the second lens, the effective diameter becomes smaller. An optical system in which the effective diameter increases from the fourth lens to the fifth lens. In the first paragraph, Among the first to eighth lenses, a plurality of lenses arranged sequentially are made of glass, and the remaining lenses arranged sequentially are made of plastic. The average effective diameter of a plurality of lenses having the above plastic material is larger than the effective diameter of a glass material lens placed on the object side of the plastic material lens. The above effective diameter is an optical system in which the effective diameters on the object side and the sensor side of each lens are averaged. In the first paragraph, Among the first to eighth lenses, a plurality of lenses arranged sequentially are made of glass, and the remaining lenses arranged sequentially are made of plastic. An optical system in which the effective diameter of the glass lens placed most adjacent to the plastic lens among the first to eighth lenses is the smallest. In the first paragraph, The first to third lenses are made of glass, The above-mentioned fourth to eighth lenses are optical systems made of plastic material. In the first paragraph, The above fifth lens has positive (+) refractive power, The above seventh lens has a negative (-) refractive power, The above eighth lens is an optical system having positive (+) refractive power. In any one of claims 1 to 6, An optical system that satisfies the following conditions. <Conditional expression> 0.4 < n2-n3 < 0.6 (In the above conditional expression, n2 represents the refractive index of the second lens, and n3 represents the refractive index of the third lens.) In any one of claims 1 to 6, An optical system that satisfies the following conditions. <Conditional expression> 20 < |L2R1| < 110 (In the above conditional expression, L2R1 means the radius of curvature of the object-side surface of the second lens.) Including first to eighth lenses arranged along the optical axis, The above first lens has a negative (-) refractive power, The above second lens has positive (+) refractive power, The above third lens has positive (+) refractive power, The above fourth lens has a negative (-) refractive power, The above sixth lens has positive (+) refractive power, An optical system in which a plurality of sequentially arranged lenses among the first to eighth lenses are made of glass, and the remaining sequentially arranged lenses are made of plastic. In paragraph 9, An optical system in which the effective diameter of the third lens among the first to eighth lenses is the smallest.

Images