Optical system and camera module

Abstract

An optical system according to an embodiment of the present invention includes first to fourth lenses disposed along the optical axis, wherein the first lens has positive (+) refractive power, the second lens has positive (+) refractive power, the third lens has negative (-) refractive power, the fourth lens has negative (-) refractive power, and the thickness of the first lens is the largest among the first to fourth lenses on the optical axis.

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, when the camera is exposed to harsh environments, such as high temperature, low temperature, moisture, or high humidity, either inside or outside a vehicle, the characteristics of the optical system change. 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 fourth lenses arranged along an optical axis, wherein the first lens has positive (+) refractive power, the second lens has positive (+) refractive power, the third lens has negative (-) refractive power, and the fourth lens has negative (-) refractive power, and among the first to fourth lenses on the optical axis, the thickness of the first lens is the largest.

[0011] Among the first to fourth lenses on the optical axis, the thickness of the second lens may be the smallest.

[0012] In the above optical axis, the first lens may have a meniscus shape convex toward the object side.

[0013] In the optical axis, the third lens may have a meniscus shape convex toward the sensor side, and in the optical axis, the fourth lens may have a meniscus shape convex toward the object side.

[0014] The distance between the first lens and the second lens on the optical axis may be greater than the distance between the third lens and the fourth lens.

[0015] The following condition can be satisfied. <Condition> 0.5 < TTL / CA_max < 1.5 (In the above condition, TTL means the distance from the object side of the first lens to the upper surface of the image sensor on the optical axis, and CA_max represents the maximum effective diameter among the object side and sensor side of the lenses.)

[0016] The following condition can be satisfied. <Condition> 4.5 < TTL < 5.5 (In the above condition, TTL means the distance from the object side of the first lens to the upper surface of the image sensor on the optical axis.)

[0017] The following condition can be satisfied. <Condition> 2.5 < CA_max / CA_min < 3.5 (In the above condition, CA_max represents the maximum effective diameter among the object sides and sensor sides of the lenses, and CA_Min represents the minimum effective diameter among the object sides and sensor sides of the lenses.)

[0018] In order to solve the above technical problem, an optical system according to the present embodiment includes first to fourth lenses arranged along an optical axis, wherein the first lens has positive (+) refractive power, the second lens has positive (+) refractive power, the third lens has negative (-) refractive power, and the fourth lens has negative (-) refractive power, and among the first to fourth lenses, the effective diameter of the fourth lens is the largest, and among the first to fourth lenses, the effective diameter of the second lens is the smallest.

[0019] Among the first to fourth lenses on the optical axis, the thickness of the first lens may be the largest, and among the first to fourth lenses on the optical axis, the thickness of the second lens may be the smallest.

[0020] The distance between the third lens and the fourth lens on the optical axis may be smaller than the thickness of the fourth lens.

[0021] In the optical axis, the third lens may have a meniscus shape convex toward the sensor side, and in the optical axis, the fourth lens may have a meniscus shape convex toward the object side.

[0022] The following condition can be satisfied. <Condition> 0.1 < ΣCG / ΣCT < 1 (In the above condition, ΣCG is the sum of the spacing between adjacent lenses, and ΣCT is the sum of the central thicknesses of the lenses.)

[0023] The following condition can be satisfied. <Condition> 0.5 < F / TTL < 1 (In the above condition, F is the effective focal length of the optical system, and TTL means the distance on the optical axis from the object side of the first lens to the upper surface of the image sensor.)

[0024] The following condition can be satisfied. <Condition> 100 < FOV_H < 110 (In the above condition, FOV_H means the horizontal angle of view of the optical system.)

[0025]

[0026] In order to solve the above technical problem, an optical system according to the present embodiment includes first to fourth lenses arranged along an optical axis, wherein the first lens has positive (+) refractive power, the second lens has positive (+) refractive power, the third lens among the first to fourth lenses has the largest thickness on the optical axis, the second lens and the fourth lens have a meniscus shape convex toward the object side on the optical axis, the first lens is made of glass, and the second to fourth lenses are made of plastic.

[0027] Among the first to fourth lenses on the optical axis, the thickness of the second lens may be the smallest.

[0028] In the optical axis, the first lens may have a meniscus shape convex toward the object side, and in the optical axis, the third lens may have a meniscus shape convex toward the sensor side.

[0029] Among the first to fourth lenses, the effective diameter of the fourth lens may be the largest, and among the first to fourth lenses, the effective diameter of the second lens may be the smallest.

[0030] The distance between the first lens and the second lens on the optical axis may be smaller than the distance between the second lens and the third lens.

[0031] The Abbe numbers (v) of the second to fourth lenses may be the same, and the refractive indices (n) of the second to fourth lenses may be the same.

[0032] The distance between the second lens and the third lens on the optical axis may be smaller than the thickness of the third lens on the optical axis.

[0033] The distance between the third lens and the fourth lens on the optical axis may be smaller than the thickness of the third lens on the optical axis.

[0034]

[0035] In order to solve the above technical problem, an optical system according to the present embodiment includes first to fourth lenses arranged along an optical axis, wherein the first lens has positive (+) refractive power, the second lens has positive (+) refractive power, the first lens is made of glass, and the second to fourth lenses are made of plastic.

[0036] Among the first to fourth lenses, the effective diameter of the fourth lens may be the largest, and among the first to fourth lenses, the effective diameter of the second lens may be the smallest.

[0037] The distance between the third lens and the fourth lens on the optical axis may be smaller than the thickness of the fourth lens.

[0038] In the optical axis, the third lens may have a meniscus shape convex toward the sensor side, and in the optical axis, the fourth lens may have a meniscus shape convex toward the object side.

[0039] The following condition can be satisfied. <Condition> 0.1 < ΣCG / ΣCT < 1 (In the above condition, ΣCG is the sum of the spacing between adjacent lenses, and ΣCT is the sum of the central thicknesses of the lenses.)

[0040] The following condition can be satisfied. <Condition> 0.5 < F / TTL < 1 (In the above condition, F is the effective focal length of the optical system, and TTL means the distance on the optical axis from the object side of the first lens to the upper surface of the image sensor.)

[0041] The following condition can be satisfied. <Condition> 40 < FOV_H < 60 (In the above condition, FOV_H means the horizontal angle of view of the optical system.)

[0042] 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.

[0043] 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.

[0044] 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.

[0045] FIG. 1 is a side cross-sectional view of an optical system and a camera module having the same according to a first embodiment.

[0046] Figure 2 is a table showing the aspherical coefficients of lenses in the optical system of Figure 1.

[0047] Fig. 3 is a table showing the Sag values ​​of the lens surfaces of the first to fourth lenses in the optical system of Fig. 1.

[0048] Figure 4 is a graph showing data on the diffraction MTF (Modulation Transfer Function) at the IR wavelength of the optical system of Figure 1.

[0049] Fig. 5 is a graph showing data on aberration characteristics at IR wavelengths of the optical system of Fig. 1.

[0050] Fig. 6 is a side cross-sectional view of an optical system and a camera module having the same according to a second embodiment.

[0051] Fig. 7 is a table showing the aspherical coefficients of lenses in the optical system of Fig. 6.

[0052] Fig. 8 is a table showing the Sag values ​​of the lens surfaces of the first to fourth lenses in the optical system of Fig. 6.

[0053] Figure 9 is a graph showing data on the diffraction MTF (Modulation Transfer Function) at the IR wavelength of the optical system of Figure 6.

[0054] Fig. 10 is a graph showing data on aberration characteristics at the IR wavelength of the optical system of Fig. 6.

[0055] Fig. 11 is a side cross-sectional view of an optical system and a camera module having the same according to a third embodiment.

[0056] Fig. 12 is a table showing the aspherical coefficients of lenses in the optical system of Fig. 11.

[0057] Fig. 13 is a table showing the Sag values ​​of the lens surfaces of the first to fourth lenses in the optical system of Fig. 11.

[0058] Figure 14 is a graph showing data on the diffraction MTF (Modulation Transfer Function) at low temperatures of the optical system of Figure 11.

[0059] Figure 15 is a graph showing data on the diffraction MTF (Modulation Transfer Function) of the optical system of Figure 11 at room temperature.

[0060] Figure 16 is a graph showing data on the diffraction MTF (Modulation Transfer Function) at high temperatures of the optical system of Figure 11.

[0061] Fig. 17 is a graph showing data on the aberration characteristics of the optical system of Fig. 11 at room temperature.

[0062] Fig. 18 is a side cross-sectional view of an optical system and a camera module having the same according to the fourth embodiment.

[0063] Fig. 19 is a table showing the aspherical coefficients of lenses in the optical system of Fig. 17.

[0064] Fig. 20 is a table showing the Sag values ​​of the lens surfaces of the first to fourth lenses in the optical system of Fig. 17.

[0065] FIG. 21 is an example of a vehicle having an optical system according to an embodiment of the invention.

[0066] Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the attached drawings.

[0067] 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.

[0068] 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.

[0069] Additionally, the terms used in this embodiment are for the purpose of describing the embodiments and are not intended to limit the present invention.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] 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.

[0074] 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.

[0075] As shown in FIGS. 1, 6, 11, and 18, the optical systems (1000, 1100, 1200, and 1300) and camera modules having the same according to the first to fourth embodiments of the present invention can be mounted inside or outside a vehicle to monitor the driver or sense external objects or lanes. The material of the lenses can be selected from glass or plastic, and the coefficient of linear expansion of glass material is lower than that of plastic material. Accordingly, glass lenses are employed to suppress changes in the focus position due to temperature changes.

[0076] Glass lenses are more expensive than plastic lenses, and it is difficult to meet the demand for cost reduction. Therefore, the lenses in the optical system (1000, 1100, 1200, 1300) are required to have a mixed configuration of glass lenses and plastic lenses. By adopting these plastic lenses, the optical system (1000, 1100, 1200, 1300) can provide a lightweight and low-cost system by reducing the thickness of the plastic lenses. In addition, the plastic lenses can provide good correction for various aberrations such as spherical aberration and chromatic aberration. In addition, since the plastic lenses can provide aspherical lenses, the distortion in the peripheral area can be minimized.

[0077] Existing glass materials have high durability, making them difficult to physically mold, and there were limitations in manufacturing the lens surface as an aspherical surface. The lenses applied to the optical systems (1000, 1100, 1200, 1300) according to the first to fourth embodiments of the present invention can be composed of lenses made of glass having an aspherical surface. A glass injection mold (GIM) can be manufactured by using a DTM (Diamond Turning Machine) that is the same as a plastic injection process to manufacture a mold and produce a curved shape on the lens surface. When a curved shape is applied to the lens surface, it can be easy to control aberration in the peripheral field (off-axis) away from the optical axis, and the TTL can be reduced, thereby miniaturizing the entire optical system.

[0078] Conventional glass lenses require post-processing such as polishing, and glass molds (GM) are processed through raw material processing and molding processes, but glass injection molds (GIMs) can be manufactured solely through injection molding, which is advantageous as it requires fewer processes and saves on materials and manufacturing costs. In addition, GIM materials feature excellent tolerances because injection molding is performed using a mold manufactured to within 1 um. In addition, GIM materials can provide excellent compensation for various aberrations such as spherical and chromatic aberrations through their aspherical shape, and can minimize distortion in the peripheral area. In addition, because GIM materials are made of glass, their optical performance can be guaranteed even when temperature changes.

[0079]

[0080] The optical system (1000, 1100, 1200, 1300) may include n lenses, where the n-th lens may be the last lens adjacent to the image sensor (500), and the (n-1)-th lens may be the lens closest to the last lens. n is an integer greater than or equal to 3, for example, 3 to 5. The n lenses may have a ratio of glass lenses to plastic lenses in the range of 1:2 to 1:3.

[0081] Within the optical system (1000, 1100, 1200, 1300), at least one lens closest to the object may be made of glass. Three or more lenses, for example, three to five 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.

[0082] At least one lens closest to the image sensor (500) within the optical system (1000, 1100, 1200, 1300) may be made of glass. For example, at least two lenses closest to the image sensor (500) may be made of glass, and preferably, at least two lenses adjacent to the image sensor (500) may be made of glass. That is, since the n-th and n-1-th lenses in the optical system (1000, 1100, 1200, 1300) are arranged as glass lenses, various aberrations can be corrected for the light incident on the image sensor (500).

[0083]

[0084] Among the lenses of the optical system (1000, 1100, 1200, 1300), the lens with the highest refractive index can be positioned adjacent to the object. The highest refractive index can be 1.8 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.

[0085]

[0086] Within the optical system (1000, 1100, 1200, 1300), a lens having a maximum effective diameter can be placed at the center of the object side and the sensor side. The effective diameter of the lens can increase and then decrease as it moves from the object side to the sensor side. The effective diameter of the lens can decrease and then increase and then decrease again as it moves from the object side to the sensor side. Through this, since the light incident on the optical system (1000, 1100, 1200, 1300) is structured to move away from the optical axis and then return to the optical axis, the optical system (1000, 1100, 1200, 1300) can form a stable optical path.

[0087] 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. "Diameter of the lens surface" may mean "effective diameter of the lens." "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 flange of the lens is not shown, the flange may be a portion that protrudes perpendicular to the optical axis from the side of the lens so that the lens is coupled to the barrel. The flange 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.

[0088] Each of the lenses (101-104, 201-204, 301-304, 401-404) 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.

[0089]

[0090] Within the optical system (1000, 1100, 1200, 1300), the TTL (Total top length) may be more than 0.5 times, for example, more than 0.5 times and less than 1 time, of 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 (500) on the optical axis (OA). The Imgh is the maximum diagonal length of the image sensor (500) on the optical axis (OA). Within the optical system (1000, 1100, 1200, 1300), the effective focal length (EFL) is provided to be 3 mm or more and the diagonal field of view (DFOV) is provided to be less than 130 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.

[0091] The optical systems (1000, 1100) of the first and second embodiments may have a TTL / Imgh condition of 0.5 or more, for example, 0.5 or more and 1 or less. The optical systems (1200, 1300) of the third and fourth embodiments may have a TTL / Imgh condition of 1 or more and 1.05 or more, for example, 1.05 or more and 1.1 or less. By satisfying the above conditions, a vehicle lens optical system can be provided. Accordingly, the optical systems (1000, 1100, 1200, 1300) can provide an image without exaggeration or distortion with respect to the formed image.

[0092]

[0093] The effective diameter is the diameter or length of the effective area where light is incident. The length of the image sensor (500) is the maximum length of the diagonal in the direction orthogonal to the optical axis (OA). In the optical systems (1000, 1100) of the first and second embodiments, the number of lenses having an effective diameter smaller than the length of the image sensor (500) may be 90% or more. In the optical systems (1200, 1300) of the third and fourth embodiments, the effective diameter of at least one plastic lens may be smaller than the length of the image sensor (500).

[0094] The lens section of the optical system (1200, 1300) of the third and fourth embodiments 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 arranged within the camera module, the weight of the camera module can be reduced, and the plastic material makes it easy to polish and process, is resistant to external impacts, has high price competitiveness, and makes it easy to secure materials. In addition, various aberrations can be corrected by the plastic lenses, thereby preventing deterioration of optical performance.

[0095] By further mixing plastic lenses into the optical systems (1200, 1300) of the third and fourth embodiments, the weight of the camera module can be reduced, the manufacturing cost can be provided at a lower cost, the deterioration of optical characteristics due to temperature change can be suppressed, various types of plastic lenses can replace glass lenses, and the polishing and processing of lens surfaces such as aspherical or free-form surfaces can be facilitated.

[0096] The first lens (301, 401) may be made of glass, and the second to fourth lenses (302-304, 402-404) may be made of plastic. The lenses made of the same material may have the same Abbe number and the same refractive index. The second to fourth lenses (302-304, 402-404) made of plastic may have the same Abbe number and the same refractive index. This ensures optical performance according to temperature changes and reduces the cost of manufacturing the lenses.

[0097]

[0098] In the lens section of the optical system (1000, 1100) of the first and second embodiments, the effective diameter of the lens closest to the object side may be larger than the effective diameter of the lens closest to the image sensor (500). In the lens section of the optical system (1200, 1300) of the third and fourth embodiments, the effective diameter of the lens closest to the object side may be smaller than the effective diameter of the lens closest to the image sensor (500). 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, 1300) 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, 1300).

[0099] The lens unit may include a first lens (101, 201, 301, 401), a second lens (102, 202, 302, 402), a third lens (103, 203, 303, 403), and a fourth lens (104, 204, 304, 404) aligned from the object side toward the sensor side along the optical axis.

[0100] The lens unit 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 may be arranged in a camera module having a plurality of inner barrels around different lenses of the lens barrel. The lens unit may be arranged in a camera module having a first inner barrel in contact with an outer surface of at least one lens of the lens barrel and a second inner barrel in contact with an outer surface of at least one lens. The lens unit may be arranged in a camera module having a plurality of inner barrels each of which is arranged between the outer surface of at least one lens or two or more lenses and the lens barrel. The lens unit may be arranged in a camera module in which the plurality of inner barrels have a material different from a material of the lens barrel.

[0101] Among the lenses constituting the lens unit, some of the lenses may be arranged in the lens barrel, and at least some of the lenses may be arranged in an inner barrel arranged within the lens barrel. Through this, the optical system (1000, 1100, 1200, 1300) can maintain resolution according to temperature changes. The lens unit may be arranged in a camera module having different barrels to minimize decentering of the lenses that expand according to temperature changes. The lens barrel in which the lens unit is arranged 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.

[0102] The minimum effective diameter within the lens section of the optical system (1000, 1100) of the first and second embodiments may be in the range of 1 mm to 2 mm, and the maximum effective diameter may be in the range of 5 mm to 7 mm. In addition, the optical system (1000, 1100) 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).

[0103] The average effective diameter of the glass materials of the optical systems (1200, 1300) of the third and fourth embodiments may be 1 mm or more, for example, in the range of 2 mm to 3 mm. The average effective diameter of the plastic material may be 2 mm or more, for example, in the range of 3 mm to 4 mm. The lens having the minimum effective diameter may be made of plastic, and the lens having the maximum effective diameter may be made of plastic. The minimum effective diameter within the lens unit may be in the range of 2 mm to 2.3 mm, and the maximum effective diameter may be in the range of 4 mm to 5 mm. In addition, the optical systems (1200, 1300) may improve the resolution and chromatic aberration control characteristics by controlling the incident light, and may improve the vignetting characteristics of the optical systems (1200, 1300).

[0104]

[0105] The optical system (1000, 1100, 1200, 1300) or camera module may include an image sensor (500). The image sensor (500) can detect light and convert it into an electrical signal. The image sensor (500) can detect light that sequentially passes through the lens section. The image sensor (500) may include an element capable of detecting incident light, such as a charge-coupled device (CCD) or a complementary metal oxide semiconductor (CMOS).

[0106]

[0107] The optical system (1000, 1100, 1200, 1300) or camera module may include a filter (600). The filter (600) may be positioned between the last lens and the image sensor (500). The filter (600) may be positioned between the lens closest to the sensor side among the lenses of the lens unit (100, 200) and the image sensor (500). For example, the filter (600) may be positioned between the nth lens and the image sensor (500).

[0108] The cover glass is placed between the filter (600) and the image sensor (500), and protects the upper portion of the image sensor (500) and can prevent a decrease in the reliability of the image sensor (500). The cover glass can be removed. The cover glass may be a protective glass.

[0109] The filter (600) may include an infrared filter or an infrared cut-off filter (IR cut-off). The filter (600) may allow light of a set wavelength band to pass through and filter out light of a different wavelength band. When the filter (600) includes an infrared filter, it may block radiant heat emitted from external light from being transmitted to the image sensor (500). In addition, the filter (600) may transmit visible light and reflect infrared light.

[0110] The optical system (1000, 1100, 1200, 1300) according to the embodiment may include an aperture (Stop). The aperture can control the amount of light incident on the optical system (1000, 1100, 1200, 1300). In the lenses arranged between the object and the aperture, the effective diameter of the lens surface tends to increase from the object side to the aperture. In the lens surfaces arranged between the aperture and the sensor, the effective diameter of the lens surfaces tends to increase from the aperture to the sensor side. The tendency for the effective diameter of the lens surfaces to increase or decrease does not only mean the case where the effective diameter of the lens surfaces increases or decreases. For example, it also includes the case where the effective diameter of the lens surfaces increases and then decreases as it goes from the aperture to the sensor side.

[0111]

[0112] In the optical systems (1000, 1100, 1200, 1300) of the first to fourth embodiments, the sum of the refractive indices of the lenses of the lens unit (100, 200) may be 5 or more, for example, in the range of 6 to 10, and the average of the refractive indices may be in the range of 1.55 to 1.8. The sum of the Abbe numbers of each of the lenses may be 170 or more, for example, in the range of 180 to 250, and the average of the Abbe numbers may be 60 or less, for example, in the range of 40 to 60. The sum of the central thicknesses of the entire lens may be 1 mm or more, for example, in the range of 1.5 mm to 3 mm, and the average of the central thicknesses may be in the range of 0.3 mm to 1 mm. The sum of the central spacings between the lenses on the optical axis (OA) may be 1.5 mm or more, for example, in the range of 1.5 mm to 2.5 mm, and may be less than the sum of the central thicknesses of the lenses. Additionally, the average value of the effective diameter of each lens surface (S1-S8) of the lens unit (100, 200) can be provided in the range of 2 mm or more, for example, 2.5 mm to 4.5 mm.

[0113]

[0114] In the optical system according to the first to fourth embodiments of the invention, the angle of view (diagonal) may be 150 degrees or less, for example, in the range of 120 to 140 degrees. The F number of the optical system or the camera module may be 2.4 or less, for example, in the range of 1.4 to 2.5. The vehicle optical system may have a horizontal field of view (FOV_H) in the Y-axis direction that may be greater than 90 degrees and less than 120 degrees, for example, in the range of 100 to 110 degrees. In addition, the vertical field of view is provided at an angle smaller than the horizontal field of view, and may be 100 degrees or less, for example, in the range of 75 to 90 degrees. 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.

[0115] 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).

[0116]

[0117] In order to more effectively prevent scratches caused by foreign substances or when placed inside a vehicle, a glass lens may be used as the first lens (101, 201), and the object-side surface of the first lens (101, 201) may have a gently curved shape so as not to come into contact with external structures. This can minimize 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 horizontal angle of view may be greater than 90 degrees and less than 110 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).

[0118] The optical system (1000, 1100, 1200, 1300) 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, 1300) toward the lenses. Hereinafter, the optical system according to the embodiment will be described in detail.

[0119]

[0120] An optical system according to a first embodiment of the invention will be described.

[0121] 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 lenses in the optical system of FIG. 1, FIG. 3 is a table showing Sag values ​​of lens surfaces of first to fourth lenses in the optical system of FIG. 1, FIG. 4 is a graph showing data on diffraction MTF (Modulation Transfer Function) at an IR wavelength of the optical system of FIG. 1, and FIG. 5 is a graph showing data on aberration characteristics at an IR wavelength of the optical system of FIG. 1.

[0122] Referring to FIG. 1, the optical system (1000) includes a lens unit (100), and the lens unit (100) may include a first lens (101) to a fourth lens (104). The first to fourth lenses (101 to 104) 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 fourth lens (104) and a filter (600) and be incident on the image sensor (500).

[0123] 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 positive (+) refractive power on the optical axis (OA). The first lens (101) is made of glass and may have an aspherical surface. At least one or both of the first surface (S1) and the second surface (S2) may be aspherical. The aspherical coefficients of the first and second surfaces (S1, S2) may be provided as S1 and S2 of L1 in FIG. 2.

[0124] 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 concave meniscus shape toward the sensor side. The first lens (101) may have a convex meniscus shape toward the object side. The first lens (101) is made of glass and may have an aspherical surface.

[0125] The refractive index (n1) of the first lens (101) can satisfy the condition of n1>1.6 or n1>1.62. If 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. If 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 this case, lens manufacturing is not easy, the lens defect rate increases, and it may cause a decrease in yield.

[0126] The aperture (Stop) may be arranged around the sensor-side second surface (S2) of the first lens (101). The aperture (Stop) may be arranged around the object-side third surface (S3) of the second lens (102). 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 110 degrees.

[0127]

[0128] The second lens (102) may be arranged second from the object side. The second lens (102) may be arranged third 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 on the optical axis (OA).

[0129] The third surface (S3) on the object side of the second lens (102) may be convex with respect to the optical axis (OA), and the fourth surface (S4) on the sensor side may be concave. The second lens (102) may have a concave meniscus shape toward the sensor. The second lens (102) may have a convex meniscus shape toward the object side. The second lens (102) is made of glass and may have an aspherical surface. At least one or both of the third surface (S3) and the fourth surface (S4) may be aspherical. 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.

[0130]

[0131] The third lens (103) may be arranged third from the object side. The third lens (103) may be arranged second 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 negative (-) 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.

[0132] The fifth surface (S5) on the object side of the third lens (103) with respect to the optical axis may be concave, and the sixth surface (S6) on the sensor side may be convex. The third lens (103) may have a meniscus shape in which the sensor side is convex. The third lens (103) may have a meniscus shape in which the object side is concave. The third lens (103) is made of glass and may be aspherical. At least one or both of the fifth surface (S5) and the sixth surface (S6) may be aspherical. The aspherical coefficients of the fifth and sixth surfaces (S5, S6) may be provided as S1 and S2 of L3 in FIG. 2. 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.

[0133]

[0134] The fourth lens (104) may be arranged closest to the sensor side. The fourth lens (104) may be arranged farthest from the object side. The fourth lens (104) may have positive (+) or negative (-) refractive power on the optical axis (OA). The fourth lens (104) may have negative (-) refractive power. The fourth lens (104) may include a plastic or glass material. For example, the fourth lens (104) may be provided as a glass material.

[0135] The seventh surface (S7) on the object side of the fourth lens (104) with respect to the optical axis may be convex, and the eighth surface (S8) on the sensor side may be concave. The fourth lens (104) may have a meniscus shape in which the object side is convex. The fourth lens (104) may have a meniscus shape in which the sensor side is concave. The fourth lens (104) is made of glass and may be aspherical. At least one or both of the seventh surface (S7) and the eighth surface (S9) may be aspherical. The aspherical coefficients of the seventh and eighth surfaces (S7, S8) may be provided as S1 and S2 of L4 in FIG. 2. 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.

[0136]

[0137] LensSurfaceRadiusThicknessndvdSemiApertureFocal length1S11.5870.6451.6460.731.1264.238 S2(stop)3.3140.597 1.017 2S32.8340.3001.6460.710.900162.024 S42.7960.609 0.930 3S5-50.4461.9220.881.011-67.962 S6-5.3000.489 1.386 4S73.4770.6011.581.612.412-9.909 S81.9110.399 2.571 FilterS15Infinity0.400 2.589Infinity S16Infinity0.316 2.612 Image Infinity0.000 2.639

[0138] 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.

[0139]

[0140] Item ValueItem ValueF4.458ET10.347ΣIndex6.698ET20.309ΣAbbe223.929ET30.387ΣCT1.993ET40.405ΣCG2.094F-number1.981CA_max5.278FOV_D129 .000CA_min1.800FOV_V84.000CA_Aver3.490FOV_H107.000CT_max0.645ImgH5.278CT_min0.300SD3.441CT_Aver0.498TTL8.890EPD2.250 BFL1.116 TD4.086

[0141] 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 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, diagonal angle of view (FOV_D) (Degree), vertical angle of view (FOV_V) (Degree), horizontal angle of view (FOV_H) (Degree), edge thickness (ET), F number, etc. of the optical system (1000).

[0142]

[0143] The center thicknesses of the first to fourth lenses (101 to 104) are represented by CT1 to CT4, the edge thicknesses at the ends of the effective areas of each lens are represented by ET1 to ET4, the center gap between two adjacent lenses is represented by CG1 to CG4, and the edge gaps between the edges of each lens are represented by EG1 to EG4. The BFL (Back focal length) is the optical axis distance from the image sensor (500) 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 (500).

[0144] As shown in FIG. 2, among the lenses of the lens unit (100) in the first embodiment, the lens surfaces of the first, second, third, and fourth lenses (101, 102, 103, and 104) may include aspherical surfaces having a 30th-order aspherical surface coefficient. For example, the first, second, third, and fourth lenses (101, 102, 103, and 104) may include lens surfaces having a 30th-order aspherical surface coefficient. As described above, the aspherical surface having a 30th-order aspherical surface coefficient (a non-zero value) 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).

[0145] When comparing the absolute values ​​of the curvature radii of each lens, the curvature radii of the sixth surface (S6) of the third lens (103) on the optical axis (OA) may be the largest among the lenses, and the curvature radii of the first surface (S1) 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 at least 2 times, for example, in the range of 3 to 5 times.

[0146] Among the lenses, there may be three or more and five or fewer surfaces having an absolute value of a curvature radius of 3 mm or less on the object side and the sensor side. The curvature radii of the object side (first surface (S1)) of the first lens (101), the object side (third surface (S3)) of the second lens (102), the sensor side (fourth surface (S4)) of the second lens (102), and the sensor side (eighth surface (S8)) of the fourth lens (104) may be 3 mm or less in absolute value. Among the lenses, there may be two or more and four or fewer surfaces having an absolute value of a curvature radius of 3 mm or more and 5 mm or less on the object side and the sensor side.

[0147] The absolute value of the curvature radius of the sensor side (second surface (S2)) of the first lens (101), the object side (fifth surface (S5)) of the third lens (103), and the object side (seventh surface (S7)) of the fourth lens (104) may be 3 mm or more and 5 mm or less. Among the lenses, the number of surfaces having an absolute value of the curvature radius of 5 mm or more among the object side and the sensor side may be 1 or more and 2 or less. The absolute value of the curvature radius of the sensor side (sixth surface (S6)) of the third lens (103) may be 5 mm or more.

[0148] The absolute value of the curvature radius of the first surface (S1) of the first lens (101) may be smaller 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 larger 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 smaller 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 larger than the absolute value of the curvature radius of the eighth surface (S8).

[0149] The ratio of the radius of curvature of each lens can satisfy the following conditions.

[0150] Condition 1: 0.1 < |L1R1 / L1R2| < 0.5

[0151] Condition 2: 1 < |L2R1 / L2R2| < 1.5

[0152] Condition 3: 0.5 < |L3R1 / L3R2| < 1

[0153] Condition 4: 1.5 < |L4R1 / L4R2| < 2

[0154]

[0155] When describing the central thickness of the lenses based on the optical axis, the central thickness (CT1) of the first lens (101) is the largest among the lenses, and the central thickness (CT2) of the second lens (102) is the smallest among the lenses. The difference between the maximum and minimum central thicknesses among the lenses may be in the range of 0.1 mm or more and 0.5 mm or less.

[0156] The central thickness of each lens may satisfy any one of the conditions below.

[0157] Condition 1: CT1 > CT2, CT3, CT4

[0158] Condition 2: CT1, CT3, CT4 > CT2

[0159] Condition 3: CT1, CT4 > CT3 > CT2

[0160] Condition 4: CT1 > CT4 > CT2, CT3

[0161]

[0162] When describing the center spacing (CG) between the lenses, the center spacing (CG2) between the second lens (102) and the third lens (103) may be maximum, and the center spacing (CG3) between the third and fourth lenses (103, 104) may be minimum. The difference between the maximum center spacing and the minimum center spacing among the spaced lens spacings may be 0.1 mm or more, for example, in the range of 0.1 mm to 0.15 mm.

[0163] The center spacing between each lens can satisfy the conditions below.

[0164] Condition 1: CG2 > CG1 > CG3

[0165] Condition 2: CG2 > CG1, CG3

[0166] Condition 3: CG1, CG2 > CG3

[0167]

[0168] Regarding the effective diameter, the lens having the maximum effective diameter may be placed between the first lens (101) closest to the object and the fourth lens (104) closest to the image sensor (500). The lens having the maximum effective diameter may be a glass lens. The lens having the maximum effective diameter may be the fourth lens (104). 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 having the maximum effective diameter may be the eighth surface (S8) of the fourth lens (104).

[0169] 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 (100). The lens surface having the minimum effective diameter may be the third surface (S3) of the second lens (102).

[0170] The effective diameter of each lens can satisfy any one of the conditions below.

[0171] Condition 1: CA_L3, CA_L4 > CA_L1 > CA_L2

[0172] Condition 2: CA_L1, CA_L3, CA_L4 > CA_L2

[0173] Condition 3: CA_L4 > CA_L3 > CA_L1, CA_L2

[0174] Condition 4: CA_L4 > CA_L1, CA_L2, CA_L3

[0175]

[0176] Regarding the refractive index, the refractive index of the third lens (103) may be the highest among the lenses and may be greater than 1.8, for example, greater than 1.9. The fourth lens (104) may have the lowest refractive index among the lenses. For example, the refractive index of the fourth lens (104) may be the lowest among the lenses and may be less than 1.52, for example, less than 1.5. The difference between the maximum refractive index and the minimum refractive index may be 0.3 or more.

[0177] The refractive index of each lens can satisfy any of the conditions below.

[0178] Condition 1: n2, n3 > n1 > n4

[0179] Condition 2: n3 > n2 > n1, n4

[0180] Condition 3: n3 > n1, n2, n4

[0181] Condition 4: n1, n2, n3 > n4

[0182]

[0183] Comparing the Abbe numbers, the Abbe number of the fourth lens (104) is the largest among the lenses and may be 50 or more. The Abbe number of the third lens (103) 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 50 or more. By providing the Abbe number of the fourth lens (104) as the largest and the Abbe number of the third lens (103) as the smallest, the chromatic dispersion of light traveling between the glass lenses can be controlled, and the chromatic dispersion between the glass lenses can be increased to guide it to the image sensor (500).

[0184] The Abbe number of each lens can satisfy any of the conditions below.

[0185] Condition 1: v4 > v1 > v2, v3

[0186] Condition 2: v1, v4 > v2 > v3

[0187] Condition 3: v1, v2, v4 > v3

[0188] Condition 4: v4 > v1, v2, v3

[0189]

[0190] The focal lengths (F1, F2) of the first and second lenses (101, 102) may have positive (+) signs. The first and second lenses (101, 102) may have positive (+) refractive power. The focal lengths (F3, F4) of the third and fourth lenses (103, 104) may have negative (-) signs. The third and fourth lenses (103, 104) may have negative (-) refractive power. The third and fourth lenses (103, 104) having negative (-) refractive power may be arranged on the sensor side of the second lens (102) having positive (+) refractive power. Through this, light incident from the object side may be gathered in the direction of the optical axis and then diverged again from the direction of the optical axis, thereby forming a stable optical path.

[0191]

[0192] When comparing the focal lengths in absolute values, the focal length of the second lens (102) is the largest among the lenses, and may be 150 or more and 200 or less. Among the lenses, the second lens (102) made of glass 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 3 or more and 5 or less. Among the lenses, the first lens (101) made of glass may have the smallest focal length and the largest refractive power.

[0193] 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 120 or more or 150 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.

[0194] The absolute value of the focal length of each lens can satisfy any of the conditions below.

[0195] Condition 1: |f2|, |f3|, |f4| > |f1|

[0196] Condition 2: |f2| > |f1|, |f3|, |f4|

[0197] Condition 3: |f2| > |f3| > |f1|, |f4|

[0198] Condition 4: |f2|, |f3| > |f4| > |f1|

[0199]

[0200] The thickness (T1) of the first lens (101) may be minimum at the edge and maximum at the center, and the maximum thickness is in the range of 1.5 to 2 times the minimum thickness. The thickness (T2) of the second lens (102) may be maximum at the edge and minimum 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 1 to 1.5 times the minimum thickness. The thickness (T4) of the fourth lens (104) 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.

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

[0202] Condition 1: 1.5 < CT1 / ET1 < 2, 0.5 < ET1 / CT1 < 1

[0203] Condition 2: 0.5 < CT2 / ET2 < 1, 1 < ET2 / CT2 < 1.5

[0204] Condition 3: 1 < CT3 / ET3 < 1.5, 0.5 < ET3 / CT3 < 1

[0205] Condition 4: 1 < CT4 / ET4 < 1.5, 0.5 < ET4 / CT4 < 1

[0206] Condition 5: 1 < ΣCT / ΣET < 1.5, 0.5 < ΣET / ΣCT < 1

[0207]

[0208] Among the gaps (G1-G6) between the lenses, the first gap (G1) between the first and second lenses (101, 102) may have a minimum in the center and a maximum at the edge. The second gap (G2) between the second and third lenses (102, 103) may have a maximum in the center and a minimum at the edge. The third gap (G3) between the third and fourth lenses (103, 104) may have a maximum in the edge and a minimum at the center.

[0209]

[0210] Among the lenses, the difference between the maximum sag value and the minimum sag value of the lens surface can satisfy the conditions below. The sag (SAG) value of the lens surface means the distance to the lens surface at intervals of 0.2 mm based on the Y-axis perpendicular to the optical axis. If the difference between the maximum sag value and the minimum sag value of the lens surface is large, it may mean that the shape change of the lens surface is large. If the difference between the maximum sag value and the minimum sag value of the lens surface is small, it may mean that the shape change of the lens surface is small. The first to fourth lenses (101-104) are made of a glass injection mold (GIM) material and can refract light to the image sensor even if the shape change is large.

[0211] Condition 1: 0.1 < |max(L1S1_SAG)-min(L1S1_SAG)| < 0.4

[0212] Condition 2: 0.1 < |max(L1S2_SAG)-min(L1S2_SAG)| < 0.2

[0213] Condition 3: 0.01 < |max(L2S1_SAG)-min(L2S1_SAG)| < 0.1

[0214] Condition 4: 0.01 < |max(L2S2_SAG)-min(L2S2_SAG)| < 0.1

[0215] Condition 5: 0.1 < |max(L3S1_SAG)-min(L3S1_SAG)| < 0.3

[0216] Condition 6: 0.1 < |max(L3S2_SAG)-min(L3S2_SAG)| < 0.3

[0217] Condition 7: 0.1 < |max(L4S1_SAG)-min(L4S1_SAG)| < 0.4

[0218] Condition 8: 0.1 < |max(L4S2_SAG)-min(L4S2_SAG)| < 0.3

[0219]

[0220] Fig. 4 is a graph showing the diffraction MTF (Modulation Transfer Function) for IR wavelengths at room temperature in the optical system of Fig. 1, and is a graph showing the luminance ratio (modulation) according to spatial frequency. Here, the IR wavelength can satisfy a range of 820 nm to 980 nm or other regions.

[0221] 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 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.

[0222] 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.

[0223]

[0224] An optical system according to a second embodiment of the invention will be described.

[0225] 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 lenses in the optical system of FIG. 6, FIG. 8 is a table showing Sag values ​​of lens surfaces of the first to fourth lenses in the optical system of FIG. 6, FIG. 9 is a graph showing data on diffraction MTF (Modulation Transfer Function) at an IR wavelength of the optical system of FIG. 6, and FIG. 10 is a graph showing data on aberration characteristics at an IR wavelength of the optical system of FIG. 6.

[0226] Referring to FIG. 6, the optical system (1100) includes a lens unit (200), and the lens unit (200) may include a first lens (201) to a fourth lens (204). The first to fourth lenses (201 to 204) 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 fourth lens (204) and a filter (600) and be incident on the image sensor (500).

[0227] 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 positive (+) 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).

[0228] 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 concave meniscus shape toward the sensor side. The first lens (201) may have a convex meniscus shape toward the object side. The first lens (201) is made of glass and may have an aspherical surface. At least one or both of the first surface (S1) and the second surface (S2) may be aspherical. The aspherical coefficients of the first and second surfaces (S1, S2) may be provided as S1 and S2 of L1 in FIG. 7.

[0229] The refractive index (n1) of the first lens (201) can satisfy the condition of n1>1.6 or n1>1.62. If 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. If 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.

[0230] The aperture (Stop) may be arranged around the sensor-side second surface (S2) of the first lens (201). The aperture (Stop) may be arranged around the object-side third surface (S3) of the second lens (202). 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 110 degrees.

[0231]

[0232] The second lens (202) may be arranged second from the object side. The second lens (202) may be arranged third 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 negative (-) refractive power on the optical axis (OA).

[0233] The object-side third surface (S3) of the second lens (202) with respect to the optical axis (OA) may be concave, and the sensor-side fourth surface (S4) may be concave. The second lens (202) may have a concave shape on both sides. The second lens (202) may be made of glass and may be aspherical. At least one or both of the third surface (S3) and the fourth surface (S4) may be aspherical. The aspherical coefficients of the third and fourth surfaces (S3, S4) may be provided as S1 and S2 of L2 in FIG. 7.

[0234] The third surface (S3) of the second lens (102) may be provided without a critical point from the optical axis (OA) to the end of the effective area. The fourth surface (S4) of the second lens (102) may have a critical point from the optical axis (OA) to the end of the effective area. When the fourth surface (S4) has a critical point, it may be located in a range of 70% to 90%, preferably in a range of 75% to 85%, of the effective radius (r42) from the optical axis (OA). The critical point of the fourth surface (S4) may be located in a range of 0.5 mm to 1 mm, preferably in a range of 0.7 mm to 0.9 mm from the optical axis (OA).

[0235] The critical point of the fourth surface (S4) is a point where the sign of the slope value with respect to the optical axis (OA) and the direction perpendicular to the optical axis (OA) changes from positive (+) to negative (-) or from negative (-) to positive (+), and may mean a point where the slope value is 0. In addition, the critical point of the fourth surface (S4) may be a point where the slope value of the tangent line passing through the lens surface increases and then decreases, or a point where the slope value decreases and then increases.

[0236]

[0237] The third lens (203) may be arranged third from the object side. The third lens (203) may be arranged second 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 negative (-) 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.

[0238] The fifth surface (S5) on the object side of the third lens (203) with respect to the optical axis may be concave, and the sixth surface (S6) on the sensor side may be convex. The third lens (203) may have a meniscus shape in which the sensor side is convex. The third lens (203) may have a meniscus shape in which the object side is concave. The third lens (203) is made of glass and may be aspherical. At least one or both of the fifth surface (S5) and the sixth surface (S6) may be aspherical. Aspheric coefficients of the fifth and sixth surfaces (S5, S6) may be provided as S1 and S2 of L3 in FIG. 7. 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.

[0239]

[0240] The fourth lens (204) may be arranged closest to the sensor side. The fourth lens (204) may be arranged farthest from the object side. The fourth lens (204) may have positive (+) or negative (-) refractive power on the optical axis (OA). The fourth lens (204) may have negative (-) refractive power. The fourth lens (204) may include a plastic or glass material. For example, the fourth lens (204) may be provided as a glass material.

[0241] The seventh surface (S7) on the object side of the fourth lens (204) with respect to the optical axis may be convex, and the eighth surface (S8) on the sensor side may be concave. The fourth lens (204) may have a meniscus shape in which the object side is convex. The fourth lens (204) may have a meniscus shape in which the sensor side is concave. The fourth lens (204) is made of glass and may be aspherical. At least one or both of the seventh surface (S7) and the eighth surface (S9) may be aspherical. Aspherical coefficients of the seventh and eighth surfaces (S7, S8) may be provided as S1 and S2 of L4 in FIG. 7. 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.

[0242]

[0243] LensSurfaceRadiusThicknessndvdSemiApertureFocal length1S11.8070.8001.7354.831.2023.384 S2(stop)5.8730.481 0.916 2S3-291.0410.5161.5080.990.959-16.683 S48.4230.489 1.004 3S5-40.7861.9220.881.010-11.960 S6-7.9590.356 1.528 4S72.3190.5931.7924.292.467-108.651 S82.0060.345 2.596 FilterS15Infinity0.400 2.605Infinity S16Infinity0.234 2.623 Image Infinity0.000 2.638

[0244] 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.

[0245]

[0246] Item ValueItem ValueF4.231ET10.412ΣIndex6.941ET20.548ΣAbbe180.995ET30.767ΣCT2.695ET40.451ΣCG1.671F-number1.981CA_max5.276FOV_D129 .000CA_min1.832FOV_V84.000CA_Aver3.501FOV_H107.000CT_max0.800ImgH5.276CT_min0.516SD3.566CT_Aver0.674TTL5.000EPD2.136 BFL0.980 TD4.366

[0247] 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, the effective diameter characteristic, the diagonal angle of view (FOV_D) (Degree), the vertical angle of view (FOV_V) (Degree), the horizontal angle of view (FOV_H) (Degree), the edge thickness (ET), the F number, etc. of the optical system (1100).

[0248]

[0249] The center thicknesses of the first to fourth lenses (201 to 204) are represented by CT1 to CT4, the edge thicknesses at the ends of the effective areas of each lens are represented by ET1 to ET4, the center gap between two adjacent lenses is represented by CG1 to CG4, and the edge gaps between the edges of each lens are represented by EG1 to EG4. The BFL (Back focal length) is the optical axis distance from the image sensor (500) 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 (500).

[0250] As shown in Fig. 7, among the lenses of the lens unit (200) in the second embodiment, the lens surfaces of the first, second, third, and fourth lenses (201, 202, 203, and 204) may include aspherical surfaces having a 30th-order aspherical surface coefficient. For example, the first, second, third, and fourth lenses (201, 202, 203, and 204) may include lens surfaces having a 30th-order aspherical surface coefficient. As described above, since the aspherical surface having a 30th-order aspherical surface coefficient (a value other than "0") can significantly change the aspherical surface shape of the periphery, the optical performance of the periphery of the field of view (FOV) can be well corrected.

[0251] When comparing the absolute values ​​of the curvature radii of each lens, the curvature radii of the third surface (S3) of the second lens (202) on the optical axis (OA) may be the largest among the lenses, and the curvature radii of the first surface (S1) 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 150 times or more, for example, in the range of 150 to 170 times.

[0252] Among the lenses, there may be two or more and four or less surfaces having an absolute value of a curvature radius of 3 mm or less on the object side and the sensor side. The curvature radii of the object side (first surface (S1)) of the first lens (201), the object side (seventh surface (S7)) of the fourth lens (204), and the sensor side (eighth surface (S8)) of the fourth lens (204) may be 3 mm or less in absolute value. Among the lenses, there may be three or more and five or less surfaces having an absolute value of a curvature radius of 3 mm or more and 10 mm or less on the object side and the sensor side.

[0253] The absolute value of the curvature radius of the sensor side (second surface (S2)) of the first lens (201), the sensor side (fourth surface (S4)) of the second lens (202), the object side (fifth surface (S5)) of the third lens (203), and the sensor side (sixth surface (S6)) of the third lens (203) may be 3 mm or more and 10 mm or less. Among the lenses, the number of surfaces having an absolute value of the curvature radius of 10 mm or more among the object side and the sensor side may be 1 or more and 2 or less. The absolute value of the curvature radius of the object side (third surface (S3)) of the second lens (202) may be 10 mm or more.

[0254] The absolute value of the curvature radius of the first surface (S1) of the first lens (201) may be smaller 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 larger 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 smaller 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 larger than the absolute value of the curvature radius of the eighth surface (S8).

[0255] The ratio of the radius of curvature of each lens can satisfy the following conditions.

[0256] Condition 1: 0.1 < |L1R1 / L1R2| < 0.5

[0257] Condition 2: 10 < |L2R1 / L2R2| < 50

[0258] Condition 3: 0.5 < |L3R1 / L3R2| < 1

[0259] Condition 4: 1 < |L4R1 / L4R2| < 1.5

[0260]

[0261] When describing the central thickness of the lenses based on the optical axis, the central thickness (CT1) of the first lens (201) is the largest among the lenses, and the central thickness (CT2) of the second lens (202) is the smallest among the lenses. The difference between the maximum and minimum central thicknesses among the lenses may be in the range of 0.1 mm or more and 0.5 mm or less.

[0262] The central thickness of each lens may satisfy any one of the conditions below.

[0263] Condition 1: CT1 > CT2, CT3, CT4

[0264] Condition 2: CT1, CT3, CT4 > CT2

[0265] Condition 3: CT1 > CT3 > CT2, CT4

[0266] Condition 4: CT1, CT3 > CT4 > CT2

[0267]

[0268] When describing the center spacing (CG) between the lenses, the center spacing (CG2) between the second lens (202) and the third lens (203) may be maximum, and the center spacing (CG3) between the third and fourth lenses (203, 204) may be minimum. The difference between the maximum center spacing and the minimum center spacing among the spaced lens spacings may be 0.1 mm or more, for example, in the range of 0.1 mm to 0.15 mm.

[0269] The center spacing between each lens can satisfy the conditions below.

[0270] Condition 1: CG2 > CG1 > CG3

[0271] Condition 2: CG2 > CG1, CG3

[0272] Condition 3: CG1, CG2 > CG3

[0273]

[0274] Regarding the effective diameter, the lens having the maximum effective diameter may be placed between the first lens (201) closest to the object and the fourth lens (204) closest to the image sensor (500). The lens having the maximum effective diameter may be a glass lens. The lens having the maximum effective diameter may be the fourth lens (204). Here, the effective diameter is the average of the effective diameters on the object-side surface and the sensor-side surface of each lens. The lens surface having the maximum effective diameter may be the eighth surface (S8) of the fourth lens (204).

[0275] 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 (200). The lens surface having the minimum effective diameter may be the second surface (S2) of the first lens (201).

[0276] The effective diameter of each lens can satisfy any one of the conditions below.

[0277] Condition 1: CA_L3, CA_L4 > CA_L1 > CA_L2

[0278] Condition 2: CA_L1, CA_L3, CA_L4 > CA_L2

[0279] Condition 3: CA_L4 > CA_L3 > CA_L1, CA_L2

[0280] Condition 4: CA_L4 > CA_L1, CA_L2, CA_L3

[0281]

[0282] Regarding the refractive index, the refractive index of the third lens (203) may be the highest among the lenses and may be greater than 1.8, for example, greater than 1.9. The second lens (202) may have the lowest refractive index among the lenses. For example, the refractive index of the second lens (202) may be the lowest among the lenses and may be less than 1.52, for example, less than 1.5. The difference between the maximum refractive index and the minimum refractive index may be 0.4 or more.

[0283] The refractive index of each lens can satisfy any of the conditions below.

[0284] Condition 1: n3, n4 > n1 > n2

[0285] Condition 2: n1, n3, n4 > n2

[0286] Condition 3: n3 > n1, n2, n4

[0287] Condition 4: n3 > n4 > n1, n2

[0288]

[0289] Comparing the Abbe numbers, the Abbe number of the second lens (202) is the largest among the lenses and may be 80 or more. The Abbe number of the third lens (203) 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 50 or more. By providing the Abbe number of the second lens (202) as the largest and the Abbe number of the third lens (203) as the smallest, the chromatic dispersion of light traveling between the glass lenses can be controlled, and the chromatic dispersion between the glass lenses can be increased to guide it to the image sensor (500).

[0290] The Abbe number of each lens can satisfy any of the conditions below.

[0291] Condition 1: v2 > v1 > v3, v4

[0292] Condition 2: v2 > v1, v3, v4

[0293] Condition 3: v1, v2, v4 > v3

[0294] Condition 4: v1, v2 > v4 > v3

[0295]

[0296] The focal length (F1) of the first lens (201) may have a positive (+) sign. The first lens (201) may have positive (+) refractive power. The focal lengths (F2, F3, F4) of the second, third, and fourth lenses (202, 203, and 204) may have negative (-) signs. The second, third, and fourth lenses (202, 203, and 204) may have negative (-) refractive power. The second, third, and fourth lenses (202, 203, and 204) having negative (-) refractive power may be arranged on the sensor side of the first lens (201) having positive (+) refractive power. Through this, light incident from the object side may be gathered in the direction of the optical axis and then moved away from the direction of the optical axis, thereby forming a stable optical path.

[0297]

[0298] When comparing the focal lengths in absolute values, the focal length of the fourth lens (204) is the largest among the lenses, and may be 100 or more and 150 or less. Among the lenses, the fourth lens (204) made of glass 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 3 or more and 5 or less. Among the lenses, the first lens (201) made of glass may have the smallest focal length and the largest refractive power.

[0299] 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 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.

[0300] The absolute value of the focal length of each lens can satisfy any of the conditions below.

[0301] Condition 1: |f2|, |f3|, |f4| > |f1|

[0302] Condition 2: |f4| > |f2| > |f1|, |f3|

[0303] Condition 3: |f2|, |f4| > |f3| > |f1|

[0304] Condition 4: |f4| > |f1|, |f2|, |f3|

[0305]

[0306] The thickness (T1) of the first lens (201) may be minimum at the edge and maximum at the center, and the maximum thickness is in the range of 1.5 to 2 times the minimum thickness. The thickness (T2) of the second lens (202) may be maximum at the edge and minimum 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 1 to 1.5 times the minimum thickness. The thickness (T4) of the fourth lens (204) 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.

[0307] The thickness of each lens can satisfy any of the conditions below.

[0308] Condition 1: 1.5 < CT1 / ET1 < 2, 0.5 < ET1 / CT1 < 1

[0309] Condition 2: 0.5 < CT2 / ET2 < 1, 1 < ET2 / CT2 < 1.5

[0310] Condition 3: 1 < CT3 / ET3 < 1.5, 0.5 < ET3 / CT3 < 1

[0311] Condition 4: 1 < CT4 / ET4 < 1.5, 0.5 < ET4 / CT4 < 1

[0312] Condition 5: 1 < ΣCT / ΣET < 1.5, 0.5 < ΣET / ΣCT < 1

[0313]

[0314] Among the gaps (G1-G6) 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 maximum in the center and a minimum 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.

[0315]

[0316] Among the lenses, the difference between the maximum sag value and the minimum sag value of the lens surface can satisfy the conditions below. The sag (SAG) value of the lens surface means the distance to the lens surface at intervals of 0.2 mm based on the Y-axis perpendicular to the optical axis. If the difference between the maximum sag value and the minimum sag value of the lens surface is large, it may mean that the shape change of the lens surface is large. If the difference between the maximum sag value and the minimum sag value of the lens surface is small, it may mean that the shape change of the lens surface is small. The first to fourth lenses (201 to 204) are made of a glass injection mold (GIM) material and can refract light to the image sensor even if the shape change is large.

[0317] Condition 1: 0.4 < |max(L1S1_SAG)-min(L1S1_SAG)| < 0.6

[0318] Condition 2: 0.01 < |max(L1S2_SAG)-min(L1S2_SAG)| < 0.08

[0319] Condition 3: 0.01 < |max(L2S1_SAG)-min(L2S1_SAG)| < 0.03

[0320] Condition 4: 0.01 < |max(L2S2_SAG)-min(L2S2_SAG)| < 0.03

[0321] Condition 5: 0.1 < |max(L3S1_SAG)-min(L3S1_SAG)| < 0.3

[0322] Condition 6: 0.1 < |max(L3S2_SAG)-min(L3S2_SAG)| < 0.3

[0323] Condition 7: 0.2 < |max(L4S1_SAG)-min(L4S1_SAG)| < 0.5

[0324] Condition 8: 0.1 < |max(L4S2_SAG)-min(L4S2_SAG)| < 0.3

[0325]

[0326] Fig. 9 is a graph showing the diffraction MTF (Modulation Transfer Function) for IR wavelengths at room temperature in the optical system of Fig. 6, and is a graph showing the modulation ratio according to spatial frequency. Here, the IR wavelength can satisfy a range of 820 nm to 980 nm or other regions.

[0327] Fig. 10 is a graph showing the aberration characteristics at room temperature in the optical system of Fig. 6. In the aberration graph of Fig. 10, spherical aberration (longitudinal spherical aberration), astigmatic field curves, and distortion are measured from left to right. In Fig. 10, 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. 10, the closer each curve is to the Y-axis, the better the aberration correction function can be interpreted. It can be seen that the optical system (1100) according to the second embodiment has measured values ​​close to the Y-axis in almost all areas. In other words, 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.

[0328] 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.

[0329]

[0330] An optical system according to a third embodiment of the invention will be described.

[0331] FIG. 11 is a side cross-sectional view of an optical system according to a third embodiment and a camera module having the same, FIG. 12 is a table showing aspherical coefficients of lenses in the optical system of FIG. 11, FIG. 13 is a table showing Sag values ​​of lens surfaces of the first to fourth lenses in the optical system of FIG. 11, FIG. 14 is a graph showing data on diffraction MTF (Modulation Transfer Function) at low temperature of the optical system of FIG. 11, FIG. 15 is a graph showing data on diffraction MTF (Modulation Transfer Function) at room temperature of the optical system of FIG. 11, FIG. 16 is a graph showing data on diffraction MTF (Modulation Transfer Function) at high temperature of the optical system of FIG. 11, and FIG. 17 is a graph showing data on aberration characteristics of the optical system of FIG. 11 at room temperature.

[0332] Referring to FIG. 1, the optical system (1200) includes a lens unit, and the lens unit may include a first lens (301) to a fourth lens (304). The first to fourth lenses (301 to 304) 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 fourth lens (304) and a filter (600) and be incident on the image sensor (500).

[0333] 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 positive (+) 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 may reduce changes in the center position and radius of curvature due to temperature changes in the surrounding environment, and may protect the incident side surface of the optical system (1200).

[0334] 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 concave meniscus shape toward the sensor side. The first lens (301) may have a convex meniscus shape toward the object side. The first lens (301) is made of glass and may have a spherical surface.

[0335] The refractive index (n1) of the first lens (301) can satisfy the condition of n1>1.7 or n1>1.8. If 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. If 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.

[0336] The aperture (Stop) may be arranged around the sensor-side second surface (S2) of the first lens (301). The aperture (Stop) may be arranged around the object-side third surface (S3) of the second lens (302). 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 30 to 60 degrees.

[0337] A field stop may be arranged on the object-side surface (first surface (S1)) of the first lens (301) or between the first lens (301) and the second lens (302). The field stop may be formed so that the surface facing the optical axis of the spacer has a protruding shape or a sharp surface. Therefore, in order to prevent ghosting due to diffuse reflection and to prevent the inflow of stray light, a field stop may be additionally arranged on the object-side surface (first surface (S1)) of the first lens (301) or between the first lens (301) and the second lens (302).

[0338]

[0339] The second lens (302) may be arranged second from the object side. The second lens (302) may be arranged third 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 in 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 plastic material.

[0340] The third surface (S3) on the object side of the second lens (302) with respect to the optical axis (OA) may be convex, and the fourth surface (S4) on the sensor side may be concave. The second lens (302) may have a concave meniscus shape toward the sensor side. The second lens (302) may have a convex meniscus shape toward the object side. The second lens (302) is made of a plastic material and may have an aspherical surface. At least one or both of the third surface (S3) and the fourth surface (S4) may be aspherical. The aspherical coefficients of the third and fourth surfaces (S3, S4) may be provided as S1 and S2 of L2 in FIG. 12. 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.

[0341]

[0342] The third lens (303) may be arranged third from the object side. The third lens (303) may be arranged second 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 negative (-) 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 plastic material.

[0343] The fifth surface (S5) on the object side of the third lens (303) with respect to the optical axis may be concave, and the sixth surface (S6) on the sensor side may be convex. The third lens (303) may have a meniscus shape in which the sensor side is convex. The third lens (303) may have a meniscus shape in which the object side is concave. The third lens (303) is made of a plastic material and may be aspherical. At least one or both of the fifth surface (S5) and the sixth surface (S6) may be aspherical. The aspherical coefficients of the fifth and sixth surfaces (S5, S6) may be provided as S1 and S2 of L3 in FIG. 12. 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.

[0344]

[0345] The fourth lens (304) may be arranged closest to the sensor side. The fourth lens (304) may be arranged farthest from the object side. The fourth lens (304) may have positive (+) or negative (-) refractive power on the optical axis (OA). The fourth lens (304) may have positive (+) refractive power. The fourth lens (304) may include a plastic or glass material. For example, the fourth lens (304) may be provided with a plastic material.

[0346] The seventh surface (S7) on the object side of the fourth lens (304) with respect to the optical axis may be convex, and the eighth surface (S8) on the sensor side may be concave. The fourth lens (304) may have a meniscus shape in which the object side is convex. The fourth lens (304) may have a meniscus shape in which the sensor side is concave. 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 (S9) may be aspherical. The aspherical coefficients of the seventh and eighth surfaces (S7, S8) may be provided as S1 and S2 of L4 in FIG. 12.

[0347] The seventh surface (S7) of the fourth lens (304) may have two or more critical points from the optical axis (OA) to the end of the effective area. When the seventh surface (S7) has critical points, the first critical point may be located in a range of 20% to 50%, preferably 30% to 40%, of the effective radius (r41) from the optical axis (OA). In addition, the second critical point may be located in a range of 60% to 90%, preferably 75% to 85%, of the effective radius (r42) from the optical axis (OA).

[0348] The first critical point of the seventh surface (S7) may be located in a range of 0.5 mm to 1 mm, preferably in a range of 0.7 mm to 0.9 mm, from the optical axis (OA). The second critical point of the seventh surface (S7) may be located in a range of 1 mm to 2 mm, preferably in a range of 1.5 mm to 1.9 mm, from the optical axis (OA).

[0349] The critical point of the seventh surface (S7) is a point where the sign of the slope value with respect to the optical axis (OA) and the direction perpendicular to the optical axis (OA) changes from positive (+) to negative (-) or from negative (-) to positive (+), and may mean a point where the slope value is 0. In addition, the critical point of the seventh surface (S7) may be a point where the slope value of the tangent line passing through the lens surface increases and then decreases, or a point where the slope value decreases and then increases.

[0350] The eighth surface (S8) of the fourth lens (304) may have a critical point from the optical axis (OA) to the end of the effective area. When the eighth surface (S8) has a critical point, it may be located in a range of 30% to 50%, preferably 35% to 45%, of the effective radius (r42) from the optical axis (OA). The critical point of the eighth surface (S8) may be located in a range of 0.5 mm to 1.5 mm, preferably 0.7 mm to 1.2 mm from the optical axis (OA). The critical point of the eighth surface (S8) may be a point where the sign of the gradient value with respect to the optical axis (OA) and the direction perpendicular to the optical axis (OA) changes from positive (+) to negative (-) or from negative (-) to positive (+), and may mean a point where the gradient value is 0. Additionally, the critical point of the 8th surface (S8) may be the point where the slope value of the tangent line passing through the lens surface increases and then decreases, or the point where the slope value decreases and then increases.

[0351]

[0352] LensSurfaceRadiusThicknessndvdSemiApertureFocal length1S11.8760.6511.8046.571.2406.432 S2(stop)2.5250.340 1.074 2S32.1660.5001.6719.001.10014.286 S42.5810.666 1.034 3S5-41.0721.6719.001.066-17.476 S6-8.1340.320 1.730 4S72.5070.7011.6719.002.332113.699 S82.3130.151 2.455 FilterS15Infinity0.700 2.504Infinity S16Infinity0.656 2.559 Image Infinity-0.004 2.638

[0353]

[0354] 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.

[0355]

[0356] Item ValueItem ValueF4.856ET10.423ΣIndex6.814ET20.447ΣAbbe303.575ET30.840ΣCT2.923ET40.407ΣCG1.325F-number1.981CA_max5.276FOV_D58 .000CA_min2.068FOV_V32.000CA_Aver3.587FOV_H48.000CT_max1.072ImgH5.276CT_min0.500SD3.749CT_Aver0.731TTL5.752EPD2.452 BFL1.503 TD4.400

[0357]

[0358] 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 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, the effective diameter characteristic, the diagonal angle of view (FOV_D) (Degree), the vertical angle of view (FOV_V) (Degree), the horizontal angle of view (FOV_H) (Degree), the edge thickness (ET), the F number, etc. of the optical system (1200).

[0359]

[0360] The center thicknesses of the first to fourth lenses (301 to 304) are represented by CT1 to CT4, the edge thicknesses at the ends of the effective areas of each lens are represented by ET1 to ET4, the center gap between two adjacent lenses is represented by CG1 to CG4, and the edge gaps between the edges of each lens are represented by EG1 to EG4. The BFL (Back focal length) is the optical axis distance from the image sensor (500) 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 (500).

[0361] As shown in Fig. 12, among the lenses of the lens unit in the third embodiment, the lens surfaces of the second, third, and fourth lenses (302, 303, and 304) may include aspherical surfaces having a 30th-order aspherical surface coefficient. For example, the second, third, and fourth lenses (302, 303, and 304) may include lens surfaces having a 30th-order aspherical surface coefficient. As described above, the aspherical surface having a 30th-order aspherical surface 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).

[0362] When comparing the absolute values ​​of the curvature radii of each lens, the curvature radii of the sixth surface (S6) of the third lens (303) on the optical axis (OA) may be the largest among the lenses, and the curvature radii of the first surface (S1) 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 3 times or more, for example, 3 to 5 times. The curvature radii of the object-side surface of the glass lens arranged on the object-side surface of the plastic lens may be the smallest among the lenses. The curvature radii of the object-side surface of the first lens (301) arranged on the object-side surface of the second lens (302) may be the smallest among the lenses.

[0363] Among the lenses, there may be 5 or more and 7 or less surfaces having an absolute value of a curvature radius of 3 mm or less on the object side and the sensor side. The curvature radius of the object side (first surface (S1)) of the first lens (301), the sensor side (second surface (S2)) of the first lens (301), the object side (third surface (S3)) of the second lens (302), the sensor side (fourth surface (S4)) of the second lens (302), the object side (seventh surface (S7)) of the fourth lens (304), and the sensor side (eighth surface (S8)) of the fourth lens (304) may be 3 mm or less in absolute value. Among the lenses, there may be 1 or more and 2 or less surfaces having an absolute value of a curvature radius of 3 mm or more and 5 mm or less on the object side and the sensor side.

[0364] The absolute value of the curvature radius of the object-side surface (the fifth surface (S5)) of the third lens (303) may be 3 mm or more and 5 mm or less. Among the lenses, there may be one or more and two or less surfaces of which the absolute value of the curvature radius is 5 mm or more, on the object-side surface and the sensor-side surface. The absolute value of the curvature radius of the sensor-side surface (the sixth surface (S6)) of the third lens (303) may be 5 mm or more.

[0365] 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.

[0366] The absolute value of the curvature radius of the first surface (S1) of the first lens (301) may be smaller 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 smaller 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 smaller 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 larger than the absolute value of the curvature radius of the eighth surface (S8).

[0367] The ratio of the radius of curvature of each lens can satisfy the following conditions.

[0368] Condition 1: 0.5 < |L1R1 / L1R2| < 1

[0369] Condition 2: 0.5 < |L2R1 / L2R2| < 1

[0370] Condition 3: 0.5 < |L3R1 / L3R2| < 1

[0371] Condition 4: 1 < |L4R1 / L4R2| < 1.5

[0372]

[0373] When describing the central thickness of the lenses based on the optical axis, the central thickness (CT3) of the third lens (303) is the largest among the lenses, and the central thickness (CT2) of the second lens (302) is the smallest among the lenses. The difference between the maximum and minimum central thicknesses among the lenses may be in the range of 0.5 mm or more and 0.8 mm or less.

[0374] The central thickness of each lens may satisfy any one of the conditions below.

[0375] Condition 1: CT3, CT4 > CT1 > CT2

[0376] Condition 2: CT1, CT3, CT4 > CT2

[0377] Condition 3: CT3 > CT1, CT2, CT4

[0378] Condition 4: CT3 > CT4 > CT1, CT2

[0379]

[0380] When describing the center spacing (CG) between the lenses, the center spacing (CG2) between the second lens (302) and the third lens (303) may be maximum, and the center spacing (CG3) between the third and fourth lenses (303, 304) may be minimum. The difference between the maximum center spacing and the minimum center spacing among the spaced lens spacings may be 0.1 mm or more, for example, in the range of 0.2 mm to 0.4 mm.

[0381] The center spacing between each lens can satisfy the conditions below.

[0382] Condition 1: CG2 > CG1 > CG3

[0383] Condition 2: CG2 > CG1, CG3

[0384] Condition 3: CG1, CG2 > CG3

[0385]

[0386] Regarding the effective diameter, the lens having the maximum effective diameter may be placed between the first lens (301) closest to the object and the fourth lens (304) closest to the image sensor (500). The lens having the maximum effective diameter may be a plastic lens. The lens having the maximum effective diameter may be the fourth lens (304). Here, the effective diameter is the average of the effective diameters on the object-side surface and the sensor-side surface of each lens. The lens surface having the maximum effective diameter may be the eighth surface (S8) of the fourth lens (304).

[0387] The lens having the minimum effective diameter may be any one of the plastic material lenses, and for example, the effective diameter of the second lens (302) 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 (302).

[0388] The effective diameter of each lens can satisfy any one of the conditions below.

[0389] Condition 1: CA_L3, CA_L4 > CA_L1 > CA_L2

[0390] Condition 2: CA_L1, CA_L3, CA_L4 > CA_L2

[0391] Condition 3: CA_L4 > CA_L3 > CA_L1, CA_L2

[0392] Condition 4: CA_L4 > CA_L1, CA_L2, CA_L3

[0393]

[0394] In terms of refractive index, the refractive index of the first lens (301) may be the largest among the lenses and may be greater than 1.7, for example, greater than 1.8. The second lens (302), the third lens (303), and the fourth lens (304) may have the smallest refractive index among the lenses. For example, the refractive indices of the second lens (302), the third lens (303), and the fourth lens (304) may be the smallest among the lenses and may be less than 1.52, for example, less than 1.5. The difference between the maximum refractive index and the minimum refractive index may be 0.3 or more. The glass material closest to the stop is provided as a high refractive index lens, and the lens adjacent to the glass material lens and the lens adjacent to the image sensor (500) are provided as low refractive index lenses made of plastic material, thereby increasing the incidence efficiency and adjusting the refractive power between the lenses made of glass material and plastic material to guide light to the image sensor (500).

[0395] The refractive index of each lens can satisfy any of the conditions below.

[0396] Condition 1: n1 > n2, n3, n4

[0397] Condition 2: n1 > n2 = n3 = n4

[0398]

[0399] Comparing the Abbe numbers, the Abbe number of the first lens (301) is the largest among the lenses and may be 40 or more. The Abbe numbers of the second lens (302), the third lens (303), and the fourth lens (304) are 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 20 or more. By providing the Abbe number of the first lens (301) as the largest and the Abbe numbers of the second lens (302), the third lens (303), and the fourth lens (304) as the smallest, the chromatic dispersion of light traveling between the lenses made of glass can be controlled, and the chromatic dispersion between the lenses made of glass and plastic can be increased to guide it to the image sensor (500).

[0400] The Abbe number of each lens can satisfy any of the conditions below.

[0401] Condition 1: v1 > v2, v3, v4

[0402] Condition 2: v1 > v2 = v3 = v4

[0403]

[0404] The focal lengths (F1, F2, F4) of the first, second, and fourth lenses (301, 302, and 304) may have positive (+) signs. The first, second, and fourth lenses (301, 302, and 304) may have positive (+) refractive power. The focal length (F3) of the third lens (303) may have negative (-) sign. The third lens (303) may have negative (-) refractive power. The third lens (303) having negative (-) refractive power may be arranged on the sensor side of the second lens (302) having positive (+) refractive power. Through this, light incident from the object side may be gathered in the direction of the optical axis and then moved away from the direction of the optical axis, thereby forming a stable optical path.

[0405]

[0406] When comparing the focal lengths in absolute values, the focal length of the fourth lens (304) is the largest among the lenses, and may be 100 or more and 150 or less. Among the lenses, the fourth lens (304) 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.

[0407] 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.

[0408] The absolute value of the focal length of each lens can satisfy any of the conditions below.

[0409] Condition 1: |f2|, |f3|, |f4| > |f1|

[0410] Condition 2: |f3|, |f4| > |f2| > |f1|

[0411] Condition 3: |f4| > |f3| > |f1|, |f2|

[0412] Condition 4: |f4| > |f1|, |f2|, |f3|

[0413]

[0414] The thickness (T1) of the first lens (301) may be minimum at the edge and maximum at the center, and the maximum thickness is in the range of 1.5 to 2 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 1.5 to 2 times the minimum thickness. The thickness (T4) of the fourth lens (304) 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.

[0415] The thickness of each lens can satisfy any of the conditions below.

[0416] Condition 1: 1.5 < CT1 / ET1 < 2, 0.5 < ET1 / CT1 < 1

[0417] Condition 2: 1 < CT2 / ET2 < 1.5, 0.5 < ET2 / CT2 < 1

[0418] Condition 3: 1 < CT3 / ET3 < 1.5, 0.5 < ET3 / CT3 < 1

[0419] Condition 4: 1.5 < CT4 / ET4 < 2, 0.5 < ET4 / CT4 < 1

[0420] Condition 5: 1 < ΣCT / ΣET < 1.5, 0.5 < ΣET / ΣCT < 1

[0421]

[0422] Among the gaps (G1-G6) between the lenses, the first gap (G1) between the first and second lenses (301, 302) may have a minimum in the center and a maximum at the edge. The second gap (G2) between the second and third lenses (302, 303) may have a maximum in the center and a minimum at the edge. The third gap (G3) between the third and fourth lenses (303, 304) may have a maximum in the edge and a minimum at the center.

[0423]

[0424] Figures 14 to 16 are graphs showing the diffraction MTF (Modulation Transfer Function) at room temperature, low temperature, and high temperature in the optical system of Figure 11, and are graphs showing the modulation ratio according to spatial frequency. As shown in Figures 14 to 16, 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.

[0425] Fig. 17 is a graph showing the aberration characteristics at room temperature in the optical system of Fig. 11. In the aberration graph of Fig. 17, spherical aberration (longitudinal spherical aberration), astigmatic field curves, and distortion are measured from left to right. In Fig. 17, 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. 17, the closer each curve is to the Y-axis, the better the aberration correction function can be interpreted. It can be seen that the optical system (1200) according to the third embodiment has measured values ​​close to the Y-axis in almost all areas. In other words, 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.

[0426] Table 7 shows changes in optical characteristics such as EFL at room temperature, low temperature, and high temperature in the optical system according to the third embodiment. It can be seen that the change rate of the optical characteristics at low temperature is 5% or less, for example, 3% or less, based on room temperature, and it can be seen that the change rate of the optical characteristics at low temperature is 5% or less, for example, 3% or less, based on room temperature. In addition, Table 3 compares the 0F MTF Peak shift amount in the optical system according to the third embodiment, and the MTF focus position shift at low and high temperatures can satisfy a range of 5 μm or less, for example, can satisfy a range of 3 μm or less, based on room temperature.

[0427]

[0428] Room temperature low temperature high temperature low temperature / Room temperature high temperature / Room temperature EFL (F) 4.85 16 4.83 17 4.88 5 29 9.59 % 100.69 % 0 F MTF Peak shift 0-1um-2um--

[0429]

[0430] Therefore, as shown in Table 7, it can be seen that the change in optical characteristics according to the temperature change from low temperature to high temperature, for example, the change rate of effective focal length (EFL) and the change rate of horizontal field of view (FOV_H), is 10% or less, that is, 5% or less, for example, in the range of 0 to 5%. This means that even if at least one or two or more plastic lenses are used, the design can enable temperature compensation for the plastic lenses, thereby preventing a decrease in the reliability of the optical characteristics.

[0431] 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.

[0432]

[0433] An optical system according to a fourth embodiment of the invention will be described.

[0434] Fig. 18 is a side cross-sectional view of an optical system and a camera module having the same according to the fourth embodiment, Fig. 19 is a table showing aspherical coefficients of lenses in the optical system of Fig. 17, and Fig. 20 is a table showing Sag values ​​of lens surfaces of the first to fourth lenses in the optical system of Fig. 17.

[0435] Referring to FIG. 18, the optical system (1300) includes a lens unit, and the lens unit may include a first lens (401) to a fourth lens (404). The first to fourth lenses (401 to 404) may be sequentially arranged along the optical axis (OA) of the optical system (1300). Light corresponding to information about an object may pass through the first lens (401) to the fourth lens (404) and the filter (600) and be incident on the image sensor (500).

[0436] The first lens (401) may be arranged closest to the object side. The first lens (401) may be arranged farthest from the sensor side. The first lens (401) may have positive (+) refractive power on the optical axis (OA). The first lens (401) may include a plastic material or a glass material, and may be made of glass, for example. The first lens (401) made of glass may reduce changes in the center position and radius of curvature due to temperature changes in the surrounding environment, and may protect the incident side surface of the optical system (1300).

[0437] The first surface (S1) on the object side of the first lens (401) with respect to the optical axis may be convex, and the second surface (S2) on the sensor side may be concave. The first lens (401) may have a concave meniscus shape toward the sensor side. The first lens (401) may have a convex meniscus shape toward the object side. The first lens (401) is made of glass and may have a spherical surface.

[0438] The refractive index (n1) of the first lens (401) can satisfy the condition of n1>1.7 or n1>1.8. If the refractive index (n1) of the first lens (401) satisfies the condition, the radius of curvature of the first and second lenses (401, 402) can be increased, and lens manufacturing can be facilitated. If the refractive index (n1) of the first lens (401) 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 (401, 402). In this case, lens manufacturing is not easy, the lens defect rate increases, and this may cause a decrease in yield.

[0439] An aperture (stop) may be arranged around the object-side first surface (S1) of the first lens (401). The aperture can reduce the TTL within the field of view range, enabling miniaturization of the optical system. 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 30 to 60 degrees.

[0440] A field stop may be arranged on the object-side surface (first surface (S1)) of the first lens (401) or between the first lens (401) and the second lens (402). The field stop may be formed so that the surface facing the optical axis of the spacer has a protruding shape or a sharp surface. Therefore, in order to prevent ghosting due to diffuse reflection and to prevent the inflow of stray light, a field stop may be additionally arranged on the object-side surface (first surface (S1)) of the first lens (401) or between the first lens (401) and the second lens (402).

[0441]

[0442] The second lens (402) may be arranged second from the object side. The second lens (402) may be arranged third from the sensor side. The second lens (402) may be arranged between the first lens (401) and the third lens (403). The second lens (402) may have positive (+) refractive power on the optical axis (OA). The second lens (402) may include a plastic or glass material. For example, the second lens (402) may be provided as a plastic material.

[0443] The third surface (S3) on the object side of the second lens (402) with respect to the optical axis (OA) may be convex, and the fourth surface (S4) on the sensor side may be concave. The second lens (402) may have a concave meniscus shape toward the sensor side. The second lens (402) may have a convex meniscus shape toward the object side. The second lens (402) is made of a plastic material and may have an aspherical surface. At least one or both of the third surface (S3) and the fourth surface (S4) may be aspherical. The aspherical coefficients of the third and fourth surfaces (S3, S4) may be provided as S1 and S2 of L2 in FIG. 19. 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.

[0444]

[0445] The third lens (403) may be arranged third from the object side. The third lens (403) may be arranged second from the sensor side. The third lens (403) may be arranged between the second lens (402) and the fourth lens (404). The third lens (403) may have positive (+) refractive power on the optical axis (OA). The third lens (403) may include a plastic or glass material. For example, the third lens (403) may be provided as a plastic material.

[0446] The fifth surface (S5) on the object side of the third lens (403) with respect to the optical axis may be concave, and the sixth surface (S6) on the sensor side may be convex. The third lens (403) may have a meniscus shape in which the sensor side is convex. The third lens (403) may have a meniscus shape in which the object side is concave. The third lens (403) is made of a plastic material and may be aspherical. At least one or both of the fifth surface (S5) and the sixth surface (S6) may be aspherical. The aspherical coefficients of the fifth and sixth surfaces (S5, S6) may be provided as S1 and S2 of L3 in FIG. 19. 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.

[0447]

[0448] The fourth lens (404) may be arranged closest to the sensor side. The fourth lens (404) may be arranged farthest from the object side. The fourth lens (404) may have positive (+) or negative (-) refractive power on the optical axis (OA). The fourth lens (404) may have negative (-) refractive power. The fourth lens (404) may include a plastic or glass material. For example, the fourth lens (404) may be provided with a plastic material.

[0449] The seventh surface (S7) on the object side of the fourth lens (404) with respect to the optical axis may be convex, and the eighth surface (S8) on the sensor side may be concave. The fourth lens (404) may have a meniscus shape in which the object side is convex. The fourth lens (404) may have a meniscus shape in which the sensor side is concave. The fourth lens (404) 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 (S9) may be aspherical. The aspherical coefficients of the seventh and eighth surfaces (S7, S8) may be provided as S1 and S2 of L4 in FIG. 19.

[0450] The seventh surface (S7) of the fourth lens (404) may have a critical point from the optical axis (OA) to the end of the effective area. When the seventh surface (S7) has a critical point, it may be located in a range of 20% to 50%, preferably 35% to 45%, of the effective radius (r42) from the optical axis (OA). The critical point of the seventh surface (S7) may be located in a range of 0.5 mm to 1 mm, preferably 0.7 mm to 0.9 mm from the optical axis (OA). The critical point of the seventh surface (S7) may be a point where the sign of the gradient value with respect to the optical axis (OA) and the direction perpendicular to the optical axis (OA) changes from positive (+) to negative (-) or from negative (-) to positive (+), and may mean a point where the gradient value is 0. Additionally, the critical point of the seventh surface (S7) may be the point where the slope value of the tangent line passing through the lens surface increases and then decreases, or the point where the slope value decreases and then increases.

[0451] The eighth surface (S8) of the fourth lens (404) may have a critical point from the optical axis (OA) to the end of the effective area. When the eighth surface (S8) has a critical point, it may be located in a range of 35% to 55%, preferably 40% to 50%, of the effective radius (r42) from the optical axis (OA). The critical point of the eighth surface (S8) may be located in a range of 0.5 mm to 1.5 mm, preferably 0.7 mm to 1.2 mm from the optical axis (OA). The critical point of the eighth surface (S8) may be a point where the sign of the gradient value with respect to the optical axis (OA) and the direction perpendicular to the optical axis (OA) changes from positive (+) to negative (-) or from negative (-) to positive (+), and may mean a point where the gradient value is 0. Additionally, the critical point of the 8th surface (S8) may be the point where the slope value of the tangent line passing through the lens surface increases and then decreases, or the point where the slope value decreases and then increases.

[0452]

[0453] LensSurfaceRadiusThicknessndvdSemiApertureFocal length1S1(stop)2.3130.6221.8046.571.2076.189 S23.8800.312 1.094 2S31.8250.5251.5356.001.00018.747 S42.0210.669 0.953 3S5-41.1211.6719.001.01955.933 S6-3.6970.4391.549 4S73.0020.7181.6520.502.187-17.371 S82.1350.159 2.346 FilterS15Infinity0.670 2.422Infinity S16Infinity0.613 2.468 Image Infinity0.002 2.541

[0454]

[0455] Table 8 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 fourth embodiment of the present invention. At this time, the unit of the radius of curvature and thickness or distance may be mm.

[0456]

[0457] Item ValueItem ValueF4.785ET10.439ΣIndex6.657ET20.487ΣAbbe142.072ET30.946ΣCT2.986ET40.362ΣCG1.419F-number1.952CA_max5.081FOV_D58 .000CA_min1.906FOV_V33.000CA_Aver3.416FOV_H48.000CT_max1.121ImgH5.081CT_min0.525SD4.564CT_Aver0.747TTL5.849EPD2.452 BFL1.444 TD4.564

[0458]

[0459] Table 9 shows the items of the mathematical formulas described above in the optical system (1300) 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, the effective diameter characteristic, the diagonal angle of view (FOV_D) (Degree), the vertical angle of view (FOV_V) (Degree), the horizontal angle of view (FOV_H) (Degree), the edge thickness (ET), the F number, etc. of the optical system (1300).

[0460]

[0461] The center thicknesses of the first to fourth lenses (401 to 404) are represented by CT1 to CT4, the edge thicknesses at the ends of the effective areas of each lens are represented by ET1 to ET4, the center gap between two adjacent lenses is represented by CG1 to CG4, and the edge gaps between the edges of each lens are represented by EG1 to EG4. The BFL (Back focal length) is the optical axis distance from the image sensor (500) 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 (401) to the upper surface of the image sensor (500).

[0462] As shown in Fig. 19, among the lenses of the lens unit in the fourth embodiment, the lens surfaces of the second, third, and fourth lenses (402, 403, and 404) may include aspherical surfaces having a 30th-order aspherical coefficient. For example, the second, third, and fourth lenses (402, 403, and 404) 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).

[0463] When comparing the absolute values ​​of the curvature radii of each lens, the curvature radii of the fifth surface (S5) of the third lens (403) on the optical axis (OA) may be the largest among the lenses, and the curvature radii of the third surface (S3) of the second lens (402) may be the smallest among the lenses. The difference between the maximum curvature radii and the minimum curvature radii may be 1.5 times or more, for example, 1.8 times to 2.5 times. The curvature radii of the object-side surface of the plastic lens arranged on the sensor side of the glass lens may be the smallest among the lenses. The curvature radii of the object-side surface of the second lens (402) arranged on the sensor side of the first lens (401) may be the smallest among the lenses.

[0464] Among the lenses, there may be three or more and five or fewer surfaces having an absolute value of a curvature radius of 3 mm or less on the object side and the sensor side. The curvature radii of the object side (first surface (S1)) of the first lens (401), the object side (third surface (S3)) of the second lens (402), the sensor side (fourth surface (S4)) of the second lens (402), and the sensor side (eighth surface (S8)) of the fourth lens (404) may be 3 or more and five or fewer surfaces having an absolute value of a curvature radius of 3 mm or more and 5 mm or less on the object side and the sensor side.

[0465] The absolute value of the radius of curvature of the sensor side (second surface (S2)) of the first lens (401), the object side (fifth surface (S5)) of the third lens (403), the sensor side (sixth surface (S6)) of the third lens (403), and the object side (seventh surface (S7)) of the fourth lens (404) may be 3 mm or more and 5 mm or less.

[0466] 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.

[0467] The absolute value of the curvature radius of the first surface (S1) of the first lens (401) may be smaller 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 (402) may be smaller 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 (403) may be larger 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 (404) may be larger than the absolute value of the curvature radius of the eighth surface (S8).

[0468] The ratio of the radius of curvature of each lens can satisfy the following conditions.

[0469] Condition 1: 0.5 < |L1R1 / L1R2| < 1

[0470] Condition 2: 0.5 < |L2R1 / L2R2| < 1

[0471] Condition 3: 0.5 < |L3R1 / L3R2| < 1

[0472] Condition 4: 1 < |L4R1 / L4R2| < 1.5

[0473]

[0474] When describing the central thickness of the lenses based on the optical axis, the central thickness (CT3) of the third lens (403) is the largest among the lenses, and the central thickness (CT2) of the second lens (402) is the smallest among the lenses. The difference between the maximum and minimum central thicknesses among the lenses may be in the range of 0.5 mm or more and 0.8 mm or less.

[0475] The central thickness of each lens may satisfy any one of the conditions below.

[0476] Condition 1: CT3, CT4 > CT1 > CT2

[0477] Condition 2: CT1, CT3, CT4 > CT2

[0478] Condition 3: CT3 > CT1, CT2, CT4

[0479] Condition 4: CT3 > CT4 > CT1, CT2

[0480]

[0481] When describing the center spacing (CG) between the lenses, the center spacing (CG2) between the second lens (402) and the third lens (403) may be the maximum, and the center spacing (CG1) between the first and second lenses (401, 402) may be the minimum. The difference between the maximum center spacing and the minimum center spacing among the spaced lens spacings may be 0.1 mm or more, for example, in the range of 0.2 mm to 0.4 mm.

[0482] The center spacing between each lens can satisfy the conditions below.

[0483] Condition 1: CG2, CG3 > CG1

[0484] Condition 2: CG2 > CG1, CG3

[0485] Condition 3: CG2 > CG3 > CG1

[0486]

[0487] Regarding the effective diameter, the lens having the maximum effective diameter may be placed between the first lens (401) closest to the object and the fourth lens (404) closest to the image sensor (500). The lens having the maximum effective diameter may be a plastic lens. The lens having the maximum effective diameter may be the fourth lens (404). 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 having the maximum effective diameter may be the eighth surface (S8) of the fourth lens (404).

[0488] The lens having the minimum effective diameter may be any one of the plastic material lenses, and for example, the effective diameter of the second lens (402) 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 (402).

[0489] The effective diameter of each lens can satisfy any one of the conditions below.

[0490] Condition 1: CA_L3, CA_L4 > CA_L1 > CA_L2

[0491] Condition 2: CA_L1, CA_L3, CA_L4 > CA_L2

[0492] Condition 3: CA_L4 > CA_L3 > CA_L1, CA_L2

[0493] Condition 4: CA_L4 > CA_L1, CA_L2, CA_L3

[0494]

[0495] In terms of refractive index, the refractive index of the first lens (401) may be the largest among the lenses and may be greater than 1.7, for example, greater than 1.8. The second lens (402) may have the smallest refractive index among the lenses. For example, the refractive index of the second lens (402) may be the smallest among the lenses and may be less than 1.6, for example, less than 1.55. The difference between the maximum refractive index and the minimum refractive index may be 0.2 or more. The glass material closest to the stop is provided as a high refractive index lens, and the lens adjacent to the glass material lens and the lens adjacent to the image sensor (500) are provided as low refractive index lenses made of plastic material, thereby increasing the incidence efficiency and adjusting the refractive power between the glass material and the plastic material lenses to guide light to the image sensor (500).

[0496] The refractive index of each lens can satisfy any of the conditions below.

[0497] Condition 1: n1 > n2, n3, n4

[0498] Condition 2: n1, n3, n4 > n2

[0499] Condition 3: n1 > n3 > n2, n4

[0500] Condition 4: n1, n3 > n4 > n2

[0501]

[0502] Comparing the Abbe numbers, the Abbe number of the second lens (402) is the largest among the lenses and may be 50 or more. The Abbe number of the third lens (403) 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 30 or more. By providing the Abbe number of the second lens (402) as the largest and the Abbe number of the third lens (403) as the smallest, the color dispersion of light traveling between the glass lenses can be controlled, and the color dispersion between the glass and plastic lenses can be increased to guide it to the image sensor (500).

[0503] The Abbe number of each lens can satisfy any of the conditions below.

[0504] Condition 1: v2 > v1 > v3, v4

[0505] Condition 2: v2 > v1, v3, v4

[0506] Condition 3: v1, v2, v4 > v3

[0507] Condition 4: v1, v2 > v4 > v3

[0508]

[0509] The focal lengths (F1, F2, F3) of the first, second, and third lenses (401, 402, and 403) may have positive (+) signs. The first, second, and third lenses (401, 402, and 403) may have positive (+) refractive power. The focal length (F3) of the fourth lens (404) may have negative (-) sign. The fourth lens (404) may have negative (-) refractive power. The fourth lens (404) having negative (-) refractive power may be arranged on the sensor side of the third lens (403) having positive (+) refractive power. Through this, light incident from the object side may be gathered in the direction of the optical axis and then diverged again from the direction of the optical axis, thereby forming a stable optical path.

[0510]

[0511] When comparing the focal lengths in absolute values, the focal length of the third lens (403) is the largest among the lenses, and may be 50 or more and 100 or less. Among the lenses, the third lens (403) made of plastic may have the largest focal length and the smallest refractive power. The focal length of the first lens (401) is the smallest among the lenses, and the absolute value of the focal length of the first lens (401) may be 5 or more and 10 or less. Among the lenses, the first lens (401) made of glass may have the smallest focal length and the largest refractive power.

[0512] Among the lenses, the lens having the minimum focal length may be the first lens (401). The difference between the maximum focal length and the minimum focal length may be 40 or more or 45 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.

[0513] The absolute value of the focal length of each lens can satisfy any of the conditions below.

[0514] Condition 1: |f2|, |f3|, |f4| > |f1|

[0515] Condition 2: |f3| > |f2| > |f1|, |f4|

[0516] Condition 3: |f3| > |f1|, |f2|, |f4|

[0517] Condition 4: |f2|, |f3| > |f4| > |f1|

[0518]

[0519] The thickness (T1) of the first lens (401) 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 (T2) of the second lens (402) 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 (403) 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. The thickness (T4) of the fourth lens (404) 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.

[0520] The thickness of each lens can satisfy any of the conditions below.

[0521] Condition 1: 1 < CT1 / ET1 < 1.5, 0.5 < ET1 / CT1 < 1

[0522] Condition 2: 1 < CT2 / ET2 < 1.5, 0.5 < ET2 / CT2 < 1

[0523] Condition 3: 1 < CT3 / ET3 < 1.5, 0.5 < ET3 / CT3 < 1

[0524] Condition 4: 1.5 < CT4 / ET4 < 2, 0.5 < ET4 / CT4 < 1

[0525] Condition 5: 1 < ΣCT / ΣET < 1.5, 0.5 < ΣET / ΣCT < 1

[0526]

[0527] Among the gaps (G1-G6) between the lenses, the first gap (G1) between the first and second lenses (401, 402) may have a minimum in the center and a maximum at the edge. The second gap (G2) between the second and third lenses (402, 403) may have a maximum in the center and a minimum at the edge. The third gap (G3) between the third and fourth lenses (403, 404) may have a maximum in the edge and a minimum at the center.

[0528]

[0529] The optical systems (1000, 1100, 1200, 1300) according to the first to fourth 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, 1300) according to the first to fourth embodiments can have improved optical characteristics. For example, when the optical systems (1000, 1100, 1200, 1300) satisfy at least one mathematical equation, the optical systems (1000, 1100, 1200, 1300) 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, 1300) 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 fourth embodiments disclosed above.

[0530]

[0531] [Mathematical Formula 1]

[0532] 0.5 < F / TTL < 1

[0533] In mathematical expression 1, 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, 401) to the upper surface of the image sensor (500). Accordingly, an optical system for a driver assistance system can be provided. When the optical system (1000, 1100, 1200, 1300) according to the embodiment satisfies mathematical expression 1, the optical system (1000, 1100, 1200, 1300) 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 in an IR wavelength. If it is below the lower limit of mathematical expression 1, the refractive power of the lenses needs to be increased, making it difficult to correct spherical aberration or distortion aberration. If it is above the upper limit of mathematical expression 1, the effective diameter or TTL of the lenses may become longer, which may cause a problem of the imaging lens system becoming larger. In the first to fourth embodiments, mathematical expression 1 may preferably satisfy 0.7 < F / TTL < 1.

[0534]

[0535] [Equation 2]

[0536] 0.5 < TTL / ImgH < 1.5

[0537] In mathematical expression 2, TTL (Total track length) means the distance (mm) from the vertex of the first surface (S1) of the first lens (101, 201, 301, 401) to the upper surface of the image sensor (500) on the optical axis (OA), and ImgH means the maximum diagonal length of the image sensor (500). When mathematical expression 2 is satisfied, the optical system (1000, 1100, 1200, 1300) can have TTL for application to the vehicle image sensor (500), thereby providing improved image quality. When it is less than the lower limit of mathematical expression 2, 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 2, the effective diameter or TTL of the lenses may become longer, which may cause a problem in that the imaging lens system becomes larger. In the first and second embodiments, mathematical expression 2 can preferably satisfy 0.8 < TTL / ImgH < 1. In the third and fourth embodiments, mathematical expression 2 can preferably satisfy 1 < TTL / ImgH < 1.3.

[0538]

[0539] [Equation 3]

[0540] 0.5 < F1 / F < 1.5

[0541] In mathematical expression 3, F1 is the focal length of the first lens (101, 201, 301, 401), and F is the effective focal length of the optical system. When mathematical expression 3 is satisfied, the optical system (1000, 1100, 1200, 1300) 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 within an appropriate TTL range through the first lens (101, 201, 301, 401) having negative (-) refractive power. When it is less than the lower limit of mathematical expression 3, the effective diameter or TTL of the lenses may become long, which may cause a problem in that the imaging lens system becomes large. If the upper limit of mathematical expression 3 is exceeded, the influence of the first lens (101, 201, 301, 401) becomes small in the entire optical system, and the refractive power of the lenses needs to be increased, which causes a problem in that correction of spherical aberration or distortion aberration becomes difficult. In the first and second embodiments, mathematical expression 3 can preferably satisfy 0.7 < F1 / F < 1. In the third and fourth embodiments, mathematical expression 3 can preferably satisfy 1.1 < F1 / F < 1.4.

[0542]

[0543] [Equation 4]

[0544] 2 < |F2| / F < 40

[0545] In mathematical expression 4, F2 is the focal length of the second lens (102, 202, 302, 402), and F is the effective focal length of the optical system. When mathematical expression 4 is satisfied, the optical system (1000, 1100, 1200, 1300) can have a set angle of view and an appropriate focal length, and an optical system for a vehicle can be provided. When it is less than the lower limit of mathematical expression 4, 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 4, the influence of the second lens (102, 202, 302, 402) becomes small in the entire optical system, 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 4 may preferably satisfy 35 < |F2| / F < 40. In the second embodiment, mathematical expression 4 can preferably satisfy 3 < |F2| / F < 5. In the third and fourth embodiments, mathematical expression 4 can preferably satisfy 2.5 < F2 / F < 4.

[0546]

[0547] [Equation 5]

[0548] 1.4 < n2 < 1.7

[0549] In mathematical expression 5, n2 is the refractive index of the second lens (102, 202, 302, 402). When mathematical expression 5 is satisfied, the second lens (102, 202, 302, 402) can minimize chromatic aberration by having a high refractive index among glass lenses. In the first and second embodiments, mathematical expression 5 can preferably satisfy 1.45 < n5 < 1.8. In the third and fourth embodiments, mathematical expression 5 can preferably satisfy 1.5 < n2 < 1.7.

[0550]

[0551] [Equation 6]

[0552] 15 < v2 < 85

[0553] In mathematical expression 6, v2 is the Abbe number of the second lens (102, 202, 302, 402). When mathematical expression 6 is satisfied, the second lens (102, 202, 302, 402) can minimize chromatic aberration by having a high Abbe number among glass lenses. In the first and second embodiments, mathematical expression 6 can preferably satisfy 58 < v2 < 82. In the third and fourth embodiments, mathematical expression 6 can preferably satisfy 18 < v3 < 22.

[0554]

[0555] [Equation 7]

[0556] 1.5 < n3 < 2

[0557] In mathematical expression 7, n3 is the refractive index of the third lens (103, 203, 303, 403). When mathematical expression 7 is satisfied, the third lens (103, 203, 303, 403) can minimize chromatic aberration by having a high refractive index among glass lenses. In the first and second embodiments, mathematical expression 7 can preferably satisfy 1.5 < n3 < 2. In the third and fourth embodiments, mathematical expression 7 can preferably satisfy 1.6 < n3 < 1.7.

[0558]

[0559] [Equation 8]

[0560] (First and Second Embodiments) 1 < CAL4S1 / TTL < 1.5

[0561] (Third and Fourth Embodiments) 0.5 < CAL4S2 / TTL < 1

[0562] In mathematical expression 8, CA_L4S1 is the effective diameter of the object-side surface (seventh surface (S7)) of the fourth lens (104, 204), CA_L4S2 is the effective diameter of the sensor-side surface (eighth surface (S8)) of the fourth lens (304, 404), and TTL (Total track length) means the distance (mm) from the vertex of the first surface (S1) of the first lens (101, 201, 301, 401) to the upper surface of the image sensor (500) on the optical axis (OA). When it is less than the lower limit of mathematical expression 8, the effective diameter of the lens arranged in the optical system (1000, 1100, 1200, 1300) becomes the largest, which causes a problem in that the TTL becomes long. If the upper limit of mathematical expression 8 is exceeded, there is a problem that the angle of view becomes excessively large compared to that satisfied by the optical system (1000, 1100, 1200, 1300). In the first and second embodiments, mathematical expression 8 can preferably satisfy 1 < CAL4S1 / TTL < 1.2. In the third and fourth embodiments, mathematical expression 8 can preferably satisfy 0.7 < CAL4S2 / TTL < 0.9.

[0563]

[0564] [Equation 9]

[0565] 1.5 < F / EPD < 2

[0566] In mathematical expression 9, F represents the effective focal length of the optical system, and EPD represents the diameter of the entrance pupil (effective aperture). When mathematical expression 9 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 fourth embodiments, mathematical expression 9 preferably satisfies 1.8 < F / EPD < 2.

[0567]

[0568] [Equation 10]

[0569] 0.1 < BFL / TTL < 0.3

[0570] In mathematical expression 10, BFL means the optical axis distance from the image sensor (500) 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, 401) to the upper surface of the image sensor (500). When mathematical expression 10 is satisfied, the optical system (1000, 1100, 1200, 1300) 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 optical system (1000, 1100, 1200, 1300) can minimize the gap between the last lens and the image sensor (500), and thus can have good optical characteristics at the periphery of the field of view (FOV). In the first and second embodiments, mathematical expression 10 can preferably satisfy 0.1 < BFL / TTL < 0.3. In the third and fourth embodiments, mathematical expression 10 can preferably satisfy 0.2 < BFL / TTL < 0.3.

[0571]

[0572] [Equation 11]

[0573] 0.5 < ET2 / CT2 < 1.5

[0574] In mathematical expression 11, ET2 is the edge thickness of the second lens (102, 202, 302, 402), and CT2 is the center thickness of the second lens (102, 202, 302, 402). The ratio of the edge thickness to the center thickness may be referred to as a thickness ratio. When mathematical expression 11 is satisfied, even if the center thickness of the second lens (102, 202, 302, 402) is the smallest in the optical system (1000, 1100, 1200, 1300), lens manufacturability may be advantageous, and lens manufacturing yield may be secured. In the first and second embodiments, mathematical expression 11 may preferably satisfy 1 < ET2 / CT2 < 1.2. In the third and fourth embodiments, mathematical expression 11 may preferably satisfy 0.8 < ET2 / CT2 < 1.

[0575]

[0576] [Equation 12]

[0577] 0.4 < ET4 / CT4 < 1

[0578] In mathematical expression 12, ET4 is the edge thickness of the fourth lens (104, 204), and CT4 is the center thickness of the fourth lens (104, 204). The ratio of the edge thickness and the center thickness may be referred to as a thickness ratio. When mathematical expression 12 is satisfied, even if the center thickness of the fourth lens (104, 204) is the smallest in the optical system (1000, 1100, 1200, 1300), lens manufacturability may be advantageous, and lens manufacturing yield may be secured. In the first and second embodiments, mathematical expression 12 may preferably satisfy 0.5 < ET4 / CT4 < 0.8. In the third and fourth embodiments, mathematical expression 12 may preferably satisfy 0.4 < ET4 / CT4 < 0.6.

[0579]

[0580] [Equation 13]

[0581] 1 < CT1 / CT2 < 2.5

[0582] In mathematical expression 13, CT1 is the central thickness of the first lens (101, 201, 301, 401), and CT2 is the central thickness of the second lens (102, 202, 302, 402). When mathematical expression 13 is satisfied, the light emitted from the first lens (101, 201, 301, 401), 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 and second embodiments, mathematical expression 13 can preferably satisfy 1.5 < CT1 / CT2 < 2.2. In the third and fourth embodiments, mathematical expression 13 can preferably satisfy 1 < CT1 / CT2 < 1.5.

[0583]

[0584] [Equation 14]

[0585] 0.1 < CT2 / CT3 < 1

[0586] In mathematical expression 13, CT2 is the central thickness of the second lens (102, 202, 302, 402), and CT3 is the central thickness of the third lens (103, 203, 303, 403). When mathematical expression 13 is satisfied, the light path of the second lens (102, 202, 302, 402) and the third lens (103, 203, 303, 403) through which the light incident on the image sensor (500) is emitted is set, and the optical system can have good optical performance at the set angle of view and focal length. In the first and second embodiments, mathematical expression 13 can preferably satisfy 0.5 < CT2 / CT3 < 0.7. In the third and fourth embodiments, mathematical expression 13 can preferably satisfy 0.3 < CT2 / CT3 < 0.5.

[0587]

[0588] [Equation 15]

[0589] 1 < CT_Max / CG_Max < 2

[0590] In mathematical expression 15, CT_Max is the maximum center thickness among the lenses, and CG_Max is the maximum gap between adjacent lenses. When mathematical expression 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 embodiment, mathematical expression 15 can preferably satisfy 1.5 < CT_Max / CG_Max < 2. In the second embodiment, mathematical expression 15 can preferably satisfy 1 < CT_Max / CG_Max < 1.7. In the third and fourth embodiments, mathematical expression 15 can preferably satisfy 1.5 < CT_Max / CG_Max < 1.7.

[0591]

[0592] [Equation 16]

[0593] 2 < CA_max / CA_min < 3.5

[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 and second embodiments, mathematical expression 16 can preferably satisfy 2.5 < CA_max / CA_min < 3. In the third and fourth embodiments, mathematical expression 16 can preferably satisfy 2.4 < CA_max / CA_min < 2.7.

[0595]

[0596] [Equation 17]

[0597] 0.1 < ΣCG / ΣCT < 1

[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 and second embodiments, mathematical expression 17 can preferably satisfy 0.4 < ΣCG / ΣCT < 0.9. In the third and fourth embodiments, mathematical expression 17 can preferably satisfy 0.4 < ΣCG / ΣCT < 0.6.

[0599]

[0600] [Equation 18]

[0601] 0.1 < CG1 / ΣCG < 0.5

[0602] In mathematical expression 18, CG1 is the center spacing between the first lens (101, 201, 301, 401) and the second lens (102, 202, 302, 402), and ΣCG is the sum of the spacings between adjacent lenses. When mathematical expression 18 is satisfied, the light emitted from the first lens (101, 201, 301, 401), 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 and second embodiments, mathematical expression 18 can preferably satisfy 0.3 < CG1 / ΣCG < 0.4. In the third and fourth embodiments, mathematical expression 18 can preferably satisfy 0.2 < CG1 / ΣCG < 0.4.

[0603]

[0604] [Equation 19]

[0605] 0.1 < CG1 / ΣCT < 0.5

[0606] In mathematical expression 19, CG1 is the center spacing between the first lens (101, 201, 301, 401) and the second lens (102, 202, 302, 402), and ΣCT is the sum of the center thicknesses of the lenses. When mathematical expression 19 is satisfied, the light emitted from the first lens (101, 201, 301, 401), 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 and second embodiments, mathematical expression 19 can preferably satisfy 0.1 < CG1 / ΣCT < 0.4. In the third and fourth embodiments, mathematical expression 19 can preferably satisfy 0.1 < CG1 / ΣCT < 0.3.

[0607]

[0608] [Equation 20]

[0609] 40 < FOV_H < 110

[0610] In mathematical expression 20, FOV_H represents the horizontal angle of view (Degree) of the optical system (1000, 1100, 1200, 1300), and can provide an angle of view suitable for a vehicle optical system. In the first and second embodiments, it is preferable that 105 < FOV_H < 110 can be satisfied. In the third and fourth embodiments, it is preferable that 45 < FOV_H < 50 can be satisfied.

[0611]

[0612] [Equation 21]

[0613] 0.5 < TTL / CA_max < 1.5

[0614] In mathematical expression 21, TTL (Total track length) means the distance (mm) from the vertex of the first surface (S1) of the first lens (101, 201, 301, 401) to the upper surface of the image sensor (500) 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 21 is satisfied, the optical system can maintain good optical performance and set a size for a slim and compact structure. In the first and second embodiments, mathematical expression 21 can preferably satisfy 0.8 < TTL / CA_max < 1.2. In the third and fourth embodiments, mathematical expression 21 can preferably satisfy 1 < TTL / CA_max < 1.2.

[0615]

[0616] [Equation 22]

[0617] 4.5 < TTL < 6

[0618] In mathematical expression 22, TTL (Total track length) means the distance (mm) from the center of the first surface (S1) of the first lens (101, 201, 301, 401) to the upper surface of the image sensor (500) on the optical axis (OA). When mathematical expression 22 is satisfied, a suitable vehicle optical system can be provided. In the first and second embodiments, mathematical expression 22 can preferably satisfy 4.5 < TTL < 5.2. In the third and fourth embodiments, mathematical expression 22 can preferably satisfy 5 < TTL < 6.

[0619]

[0620] [Equation 23]

[0621] 4.5 < ImgH < 6

[0622] Mathematical expression 23 indicates that ImgH represents the maximum diagonal length of the image sensor (500). Mathematical expression 23 can set the diagonal size of the image sensor (500) and provide an optical system having a sensor size for a vehicle. In the first and second embodiments, Mathematical expression 23 can preferably satisfy 5 < ImgH < 5.5. In the third and fourth embodiments, Mathematical expression 23 can preferably satisfy 4.8 < ImgH < 5.3.

[0623]

[0624] [Equation 24]

[0625] 0.5 < BFL < 2

[0626] In mathematical expression 24, BFL is the optical axis distance from the image sensor (500) to the center of the sensor side of the last lens. When mathematical expression 24 is satisfied, the installation space of the filter (600) and the cover glass can be secured, the assembling of the components can be improved through the gap between the image sensor (500) and the last lens, and the joint reliability can be improved. When BFL is less than the range of mathematical expression 24, 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 24, stray light may be introduced, which may deteriorate the aberration characteristics of the optical system. In the first and second embodiments, mathematical expression 24 can preferably satisfy 0.8 < BFL < 1.2. In the third and fourth embodiments, mathematical expression 24 can preferably satisfy 1.3 < BFL < 1.6.

[0627]

[0628] [Equation 25]

[0629] 3 < F < 5

[0630] Mathematical expression 25 can set the overall focal length (F) to suit the vehicle optical system. In the first to fourth embodiments, mathematical expression 25 can satisfy 4 < F < 5.

[0631]

[0632] [Equation 26]

[0633] 0.1 < CAL1 / ImgH < 0.5

[0634] In mathematical expression 26, CAL1 is the effective diameter of the first lens (101, 201, 301, 401), and ImgH represents the maximum diagonal length of the image sensor (500). If it is less than the lower limit of mathematical expression 26, the effective diameter of the lens arranged in the optical system (1000, 1100, 1200, 1300) becomes larger, which causes a problem in that the TTL becomes longer. If it exceeds the upper limit of mathematical expression 26, there is a problem in that the angle of view becomes excessively larger than that satisfied by the optical system (1000, 1100, 1200, 1300). In the first to fourth embodiments, mathematical expression 26 can preferably satisfy 0.3 < CAL1 / ImgH < 0.5.

[0635]

[0636] [Equation 27]

[0637] 0.1 < CAL1 / TTL < 0.5

[0638] In mathematical expression 27, CAL1 is the effective diameter of the first lens (101, 201, 301, 401), and TTL (Total track length) means the distance (mm) from the vertex of the first surface (S1) of the first lens (101, 201, 301, 401) to the upper surface of the image sensor (500) on the optical axis (OA). When mathematical expression 27 is satisfied, the effective diameter of the first lens (101, 201, 301, 401) that has a short total length and is arranged closest to the object side can be designed to be small. In the first and second embodiments, mathematical expression 27 can preferably satisfy 0.2 < CAL1 / TTL < 0.5. In the third and fourth embodiments, mathematical expression 27 can preferably satisfy 0.3 < CAL1 / TTL < 0.5.

[0639]

[0640] [Equation 28]

[0641] 2 < CAL1 / CT1 < 5

[0642] In mathematical expression 28, CAL1 is the effective diameter of the first lens (101, 201, 301, 401), and CT1 is the central thickness of the first lens (101, 201, 301, 401). When mathematical expression 28 is satisfied, the effective diameter of the first lens (101, 201, 301, 401) arranged closest to the object side can be designed to be small, thereby reducing the feeling of being watched by the driver. In the first to fourth embodiments, mathematical expression 28 can preferably satisfy 2 < CAL1 / CT1 < 4.

[0643]

[0644] [Equation 29]

[0645]

[0646] In mathematical expression 29, Z can represent Sag, which is the distance from any position on the aspherical surface to the vertex of the aspherical surface along 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 coefficients.

[0647]

[0648] The optical systems (1000, 1100, 1200, 1300) according to the first to fourth embodiments may satisfy at least one or two or more mathematical expressions from mathematical expressions 1 to 29. In this case, the optical systems (1000, 1100, 1200, 1300) may have improved optical characteristics. Specifically, when the optical systems (1000, 1100, 1200, 1300) satisfy at least one or two or more mathematical expressions from mathematical expressions 1 to 29, the optical systems (1000, 1100, 1200, 1300) may have improved resolution and may improve aberration and distortion characteristics. In addition, the optical system (1000, 1100, 1200, 1300) can secure a BFL (Back focal length) for applying a vehicle image sensor (500), compensate for the deterioration of optical characteristics due to temperature change, and minimize the gap between the last lens and the image sensor (500), thereby providing good optical performance in the center and periphery of the field of view (FOV).

[0649]

[0650] Table 10 shows the result values ​​for the mathematical expressions 1 to 29 described above in the optical system (1000, 1100, 1200, 1300) of the embodiment. Referring to Table 10, it can be seen that the optical system (1000, 1100, 1200, 1300) satisfies at least one, two or more, or three or more of the mathematical expressions 1 to 29. In detail, it can be seen that the optical system (1000, 1100, 1200, 1300) according to the embodiment satisfies all of the mathematical expressions 1 to 29. Accordingly, the optical system (1000, 1100, 1200, 1300) can have good optical performance and excellent optical characteristics at the center and periphery of the field of view (FOV).

[0651]

[0652] Mathematical Formula Example 1 Example 2 Example 3 Example 4 Example 10.5 < F / TTL < 10.930.850.840.8220.5 < TTL / ImgH < 1.50.910.951.091.1530.5 < F1 / F < 1.50.950.801.321.2942 < |F2| / F < 4036.3463.9422.9413.91851.4 < n2 < 1.71.641.501.671.53615 < v2 < 8560.0081.00191971.5 < n3 < 21.921.921.671.678 (First and Second Embodiments) 1 < CAL4S1 / TTL < 1.5 (Third and Fourth Embodiments) 0.5 < CAL4S2 / TTL < 11.0701.0380.8540.80291.5 < F / EPD < 21.9811.9811.9811.952100.1 < BFL / TTL < 0.30.2320.1950.2610.246110.5 < ET2 / CT2 < 1.51.0301.0630.8940.927120.4 < ET4 / CT4 < 10.6740.7600.5810.504131 < CT1 / CT2 < 2.52.1501.5511.3021.183140.1 < CT2 / CT3 < 10.6720.6560.4660.469151 < CT_Max / CG_Max < 21.0591.6351.6091.675162 < CA_max / CA_min < 3.52.8572.8352.5522.665170.1 < ΣCG / ΣCT < 10.8510.4920.4530.475180.1 < CG1 / ΣCG < 0.50.3520.3630.2560.220190.1 < CG1 / ΣCT < 0.50.3000.1780.1160.3042040 < FOV_H < 110107.000107.00048.00048.000210.5 < TTL / CA_max < 1.50.9340.9631.0901.151224.5 < TTL < 64.8035.0005.7525.849234.5 < ImgH < 65.2785.2765.2765.081240.5 < BFL < 21.1160.9801.5031.444253 < F < 54.4584.2314.8564.785260.1 < CAL1 / ImgH < 0.50.4060.4010.4380.452270.1 < CAL1 / TTL < 0.50.2410.4240.4020.393282 < CAL1 / CT1 < 53.3222.6483.5523.702.

[0653]

[0654] Fig. 21 is an example of a plan view of a vehicle to which a camera module or optical system according to an embodiment of the invention is applied. Referring to Fig. 21, a vehicle camera system according to an embodiment of the invention includes an image generating unit (11), a first information generating unit (12), a second information generating unit (21, 22, 23, 24, 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.

[0655] 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.

[0656] 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.

[0657] 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.

[0658]

[0659] 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.

[0660] In addition, although the above description focuses on examples, these are merely examples and do not limit the present invention. Those skilled in the art to which the present invention pertains will appreciate that various modifications and applications not exemplified above are possible without departing from the essential characteristics of the present invention. For example, each component specifically shown in the examples can be modified and implemented. In addition, differences related to such modifications and applications should be interpreted as being included within the scope of the present invention defined in the appended claims.

Claims

1. Including first to fourth lenses arranged along the optical axis, The above first lens has positive (+) refractive power, The above second lens has positive (+) refractive power, The above third lens has a negative (-) refractive power, The above fourth lens has a negative (-) refractive power, An optical system in which the thickness of the first lens among the first to fourth lenses on the optical axis is the greatest.

2. In paragraph 1, An optical system in which the thickness of the second lens among the first to fourth lenses on the optical axis is the smallest.

3. In paragraph 1, An optical system in which the first lens has a meniscus shape convex toward the object side on the optical axis.

4. In paragraph 1, In the above optical axis, the third lens has a convex meniscus shape toward the sensor, An optical system in which the fourth lens has a meniscus shape convex toward the object side on the optical axis.

5. In paragraph 1, An optical system in which the distance between the first lens and the second lens on the optical axis is greater than the distance between the third lens and the fourth lens.

6. In any one of paragraphs 1 to 5, An optical system that satisfies the following conditions. <Conditional expression> 0.5 < TTL / CA_max < 1.5 (In the above conditional expression, TTL means the distance on the optical axis from the object side of the first lens to the upper surface of the image sensor, and CA_max represents the maximum effective diameter among the object side and sensor side of the lenses.) 7. In any one of paragraphs 1 to 5, An optical system that satisfies the following conditions. <Conditional expression> 4.5 < TTL < 5.5 (In the above conditional expression, TTL means the distance on the optical axis from the object side of the first lens to the upper surface of the image sensor.) 8. In any one of paragraphs 1 to 5, An optical system that satisfies the following conditions. <Conditional expression> 2.5 < CA_max / CA_min < 3.5 (In the above conditional expression, CA_max represents the maximum effective diameter among the object sides and sensor sides of the lenses, and CA_Min represents the minimum effective diameter among the object sides and sensor sides of the lenses.) 9. Including first to fourth lenses arranged along the optical axis, The above first lens has positive (+) refractive power, The above second lens has positive (+) refractive power, The above third lens has a negative (-) refractive power, The above fourth lens has a negative (-) refractive power, Among the first to fourth lenses, the effective diameter of the fourth lens is the largest, An optical system in which the effective diameter of the second lens among the first to fourth lenses is the smallest.

10. In paragraph 9, Among the first to fourth lenses on the optical axis, the thickness of the first lens is the largest, An optical system in which the thickness of the second lens among the first to fourth lenses on the optical axis is the smallest.

Images