Lens device and camera device including same

Abstract

The present invention relates to a lens device comprising a front lens group, an aperture, and a rear lens group sequentially arranged in a direction from an object to an image sensor, wherein the front lens group has negative refractive power as a whole, the rear lens group has positive refractive power as a whole, the front lens group includes a first lens group having negative refractive power and a second lens group having positive refractive power and having a rear surface convex toward the image sensor, and when the entire focal distance of the entire including the front lens group, the aperture, and the rear lens group is f, and the focal distance of the second lens group is f2, f2 / f > 1.6 is satisfied, such that the refractive power and the focal distance are adjusted to clearly contain all images of a wide depth from a short distance to a long distance.

Description

Lens device and camera device equipped with the same

[0001] The present invention relates to a lens device for detecting objects at close range and a camera device equipped with the same. More specifically, the invention relates to a lens device equipped with a high-resolution near-field wide-angle lens having a wide depth of field and small distortion while achieving a compact size, and a camera device equipped with the same.

[0002]

[0003] The lens device is used within the camera device and transmits light from an object to the image sensor within the camera device.

[0004] Meanwhile, among camera devices, small camera devices are used, for example, in medical endoscopes.

[0005] Lens devices within camera units used in medical endoscopes are trending toward smaller size and higher resolution.

[0006] Currently, lens devices within camera units used in medical endoscopes provide approximately HD images. However, there is an increasing need to provide Full HD or higher resolution images to improve diagnostic accuracy and reduce reading times.

[0007] Accordingly, research is being conducted on camera devices and lens devices within camera devices to provide Full HD or higher quality video.

[0008] Meanwhile, there is a problem that the optical design difficulty for the lens device increases because the outer diameter of the lens device within the camera device used in medical endoscope devices must be small (e.g., about 5 mm or less) and high resolution must be achieved within a limited size.

[0009] To become a high-performance endoscopic optical system capable of accurately observing the condition of the stomach, it must simultaneously form images of nearby objects while clearly capturing images with a wide depth of field. However, due to the nature of wide-angle lenses, significant distortion can occur. If the distortion is severe, images at the edges of the field of view become difficult to see, causing difficulties when analyzing endoscopic images.

[0010] Therefore, it is necessary to implement an endoscopic optical system that achieves a wide angle at close range, possesses high-resolution images of wide depth of field, and has low distortion.

[0011] In addition, if the endoscope is to be used as a disposable item, there is a need to develop an optical system that can lower manufacturing costs and improve mass producibility.

[0012] In this regard, U.S. registered patent US8477436B2 discloses an objective lens for an endoscope composed of five lenses.

[0013] The rear surface of the second lens, which is positioned second from the front, is formed concavely in the above objective lens. Additionally, assuming f0 is the combined focal length of the front lens group and f1 is the focal length of the first lens, it is configured to satisfy |f0 / f1|<1.1.

[0014] However, the above-described lens has limitations in that it is too large for use in a miniaturized endoscope designed for insertion into the human body, and the low power of the first lens degrades performance when a wide angle is achieved, and places a power burden on the second lens, weakening the refractive power of the front lens group positioned in front of the aperture, resulting in severe distortion.

[0015] In addition, U.S. registered patent US8422150B2 discloses an objective wide-angle device.

[0016] The above objective wide-angle device satisfies 0 ≤ r2 / r1 < 0.24 when the radius of curvature of the front surface of the first lens is r1 and the radius of curvature of the rear surface of the first lens is r2.

[0017] However, when having r1 as described above, there are limitations such as low assemblability and difficulty in reducing distortion.

[0018] In addition, Japanese registered patent JP7285091B2 discloses an imaging optical system and an imaging device.

[0019] The above imaging optical system satisfies 1.10 ≤ f2 / f ≤ 1.60 when the focal length of the entire imaging optical system is f and the focal length of the second lens is f2, and satisfies 1.47 ≤ f3 / f ≤ 1.90 when the focal length of the third lens is f3. In addition, when the Abbe number of the second lens is V2, it satisfies 47.0 ≤ V2 ≤ 60.0. In addition, when the radius of curvature of the rear surface of the second lens is RG2R2, it satisfies -1.20 ≤ RG2R2 / f ≤ -0.40.

[0020] However, if the above conditions are satisfied, there is a limitation in that it is difficult to secure a wide depth of field because the positive refractive power of the second lens is strong, and the difference in Abbe number between the material of the first lens and the material of the second fswm is small, resulting in reduced resolution.

[0021] In addition, Korean registered patent KR10-1429890B1 discloses a compact wide-angle lens system.

[0022] The above wide-angle lens system satisfies -8 < F1 / F2 < -3, where the second to fourth lenses have positive refractive power and the fifth lens has negative refractive power, and the combined focal length of the first lens group positioned in front of the aperture is F1 and the combined focal length of the second lens group positioned behind the aperture is F2.

[0023] However, under the above conditions, positive refractive power is concentrated in the second to fourth lenses, resulting in a high power burden; therefore, strong negative refractive power must be applied to the first lens, and in this case, there is a limit in that the outer diameter of the first lens becomes large.

[0024]

[0025] The present invention was created to improve upon the problems of conventional lens devices as described above, and aims to provide a lens device capable of clearly capturing images with a wide depth of field ranging from near to far distances when an endoscope optical system forms an image of an object.

[0026] In addition, the purpose is to provide a lens device that is a wide-angle lens yet can minimize distortion.

[0027] In addition, the purpose is to provide a lens device that is a wide-angle lens and also miniaturized.

[0028] In addition, the purpose is to provide a lens device that is low-cost and mass-producible for disposable use.

[0029] In addition, the purpose is to provide a lens device capable of achieving high resolution so as to allow detailed observation of lesions, lumps, cells, etc.

[0030]

[0031] To achieve the above-mentioned purpose, the lens device according to the present invention comprises a front lens group, an aperture, and a rear lens group arranged sequentially from the direction of an object to the direction of an image sensor, wherein the front lens group has a negative refractive power overall and the rear lens group has a positive refractive power overall, and the front lens group comprises: a first lens group having a negative refractive power; and a second lens group having a positive refractive power, wherein the rear surface is convex toward the direction of the image sensor; and when the total focal length including the front lens group, the aperture, and the rear lens group is denoted as f and the focal length of the second lens group is denoted as f2, f2 / f > 1.6 is satisfied.

[0032] Preferably, f2 / f ≥ 3.0 can be satisfied.

[0033] At this time, at least a portion of the front surface of the first lens group may be concave.

[0034] In addition, the first lens group may be formed of a plastic material.

[0035] Meanwhile, in the lens device according to the present invention, the rear lens group is sequentially arranged with a third lens group, a fourth lens group, and a fifth lens group in the direction from the object to the image sensor, and the fourth lens group may have negative refractive power.

[0036] At this time, the third lens group and the fifth lens group may each have a positive refractive power.

[0037] In addition, the fifth lens group may be formed of plastic material.

[0038] In addition, at least one of the front and rear surfaces of the first to fifth lens groups may be aspherical.

[0039] Meanwhile, let H be the effective radius of the rear surface of the first lens group, and L1BS be the length in the optical axis direction from the center point of the rear surface of the first lens group to the effective aperture position, then L1BS / H < 0.8 can be satisfied.

[0040] In addition, when the distance from the front of the first lens group to the aperture is denoted as Ts and the distance from the front of the first lens group to the sensing surface of the image sensor is denoted as TTL, 0.25 < Ts / TTL < 0.7 can be satisfied.

[0041] In addition, when the distance from the front of the first lens group to the aperture is denoted as Ts and the distance from the front of the first lens group to the sensing surface of the image sensor is denoted as TTL, 0.4 < Ts / TTL < 0.6 can be satisfied.

[0042] In addition, when the focal length of the above-mentioned front lens group is GaF, GaF / F < -1 can be satisfied.

[0043] Meanwhile, when the radius of curvature of the front surface of the first lens group is denoted as R1 and the radius of curvature of the rear surface of the first lens group is denoted as R2, R2 / R1 < 0 can be satisfied.

[0044] In addition, when Y is the distance from the center of the image to the peak edge on the image plane, Y / F > 1 can be satisfied.

[0045] In addition, when the Abbe number of the lens of the second lens group is denoted as V2, 15 < V2 < 35 can be satisfied.

[0046] In addition, when the Abbe number of the lens of the first lens group is V1 and the Abbe number of the second lens group is V2, 20 < |V1-V2| can be satisfied.

[0047]

[0048] As explained above, the lens device according to the present invention has the effect of clearly capturing images of a wide depth of field from near distance to far distance by adjusting the refractive power and focal length.

[0049] In addition, by forming a concave portion of the front of the first lens group, it is possible to minimize distortion while maintaining the wide-angle lens effect.

[0050] In addition, by forming the rear surface of the second lens group convexly, it is possible to achieve the effect of being a wide-angle lens while still being compact.

[0051] In addition, by setting the first lens group to have negative refractive power and the second lens group to have positive refractive power, the front lens group is set to have negative refractive power and the rear lens group is set to have positive refractive power, thereby creating the effect of creating a focus at a short distance.

[0052] In addition, manufacturing the lens as a plastic aspherical injection-molded lens results in low production costs and the ability to mass-produce.

[0053] In addition, by adjusting the distance between the lenses, it is possible to achieve high resolution so that lesions, lumps, cells, etc. can be observed in detail.

[0054]

[0055] FIG. 1 is a schematic exploded view of a camera device according to one embodiment of the present invention.

[0056] FIG. 2 is a cross-sectional view in the optical axis direction of a lens device in a camera device according to one embodiment of the present invention.

[0057] Figures 3a to 5 show lens data according to Example 1 of the lens device of the present invention of Figure 2.

[0058] Figures 6a to 8 show lens data according to Example 2 of the lens device of the present invention of Figure 2.

[0059] Figures 9a to 11 show lens data according to Example 3 of the lens device of the present invention of Figure 2.

[0060]

[0061] Preferred embodiments of the present invention will be described in detail below with reference to the attached drawings.

[0062] The present invention is capable of various modifications and may have various embodiments, and specific embodiments are illustrated in the drawings and described in detail in the detailed description. This is not intended to limit the present invention to specific embodiments, and should be interpreted to include all modifications, equivalents, and substitutions that fall within the spirit and scope of the invention.

[0063] In describing the present invention, terms such as "first," "second," etc., may be used to describe various components, but said components may not be limited by said terms. Such terms are used solely for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be named the second component, and similarly, the second component may be named the first component.

[0064] The term "and / or" may include a combination of multiple related listed items or any of the multiple related listed items.

[0065] When it is stated that one component is "connected" or "connected" to another component, it can be understood that while it may be directly connected or connected to that other component, there may also be other components in between. On the other hand, when it is stated that one component is "directly connected" or "directly connected" to another component, it can be understood that there are no other components in between.

[0066] The terms used in this application are used merely to describe specific embodiments and are not intended to limit the invention. Singular expressions may include plural expressions unless the context clearly indicates otherwise.

[0067] In this application, terms such as “comprising” or “having” are intended to indicate the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not excluding in advance the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0068] Unless otherwise defined, all terms used herein, including technical or scientific terms, may have the same meaning as generally understood by those skilled in the art to which the present invention pertains. Terms such as those defined in commonly used dictionaries may be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and may not be interpreted in an ideal or overly formal sense unless explicitly defined in this application.

[0069] In addition, the following embodiments are provided to explain more completely to those with average knowledge in the industry, and the shapes and sizes of the elements in the drawings may be exaggerated for clearer explanation.

[0070]

[0071] Referring to FIG. 1, a camera device (10) according to one embodiment of the present invention includes a lens device (100) and an image sensor (200) that converts light from the lens device (100) into an electrical signal.

[0072] The lens device (100) receives light from an object (or subject) in front, and the image sensor (200) can convert the light received by the lens device (100) into an electrical signal.

[0073] Meanwhile, when a camera device (10) according to one embodiment of the present invention is used in an endoscope, it is preferable that the diameter of the lens device (100) or the lens within the lens device (100) be 5mm or 5.5mm or less.

[0074] As such, if the lens within the lens device (100) is a micro-lens, processing the lens becomes difficult. Alternatively, even if processing the lens is possible, the difficulty of production increases, leading to a decrease in yield and an increase in manufacturing costs. This is especially true when using plastic-based materials.

[0075] The lens device (100) of the present invention can achieve high-resolution optical performance while reducing size even when using a plastic-based material as the lens material, and can secure a short manufacturing time and stable yield through an injection molding process.

[0076] A lens device (100) according to one embodiment of the present invention may be positioned between an object (or object surface) (OBJ) and an image sensor (or image sensing surface) (IMG). The lens device (100) may sequentially include a front lens group (FLG), an aperture (STO), and a rear lens group (RLG) in the direction from the object (OBJ) to the image sensor (IMG).

[0077] Meanwhile, according to the embodiment, a cover glass (A6) may be placed in front of the image sensor (IMG).

[0078] The front lens group (FLG) may sequentially include a first lens group (L1) and a second lens group (L2) from the object (OBJ) toward the image sensor (IMG).

[0079] The rear lens group (RLG) may include a third lens group (L3), a fourth lens group (L4), and a fifth lens group (L5) sequentially from the object (OBJ) toward the image sensor (IMG).

[0080] Each of the first lens group (L1) to the fifth lens group (L5) may be composed of a single element, but may also be composed of multiple elements. Accordingly, the term "group" may be used in the first lens group (L1) to the fifth lens group (L5).

[0081] Each of the first lens group (L1) to the fifth lens group (L5) may have mutually symmetric lens characteristics with respect to the optical axis (OX).

[0082] The front lens group (FLG) may have a negative refractive power overall, and the rear lens group (RLG) may have a positive refractive power overall. Individually, the first lens group (L1) and the fourth lens group (L4) may each have a negative refractive power, and the second lens group (L2), the third lens group (L3), and the fifth lens group (L5) may each have a positive refractive power.

[0083] Through this, performance can be improved by ensuring that positive and negative refractive forces are distributed so that positive refractive forces are not concentrated in the middle part of the optical axis (OX).

[0084] In addition, it has the effect of creating a focus at close range.

[0085]

[0086] In FIG. 2, the first to fourth lights (F1 to F4) are exemplified as light incident from the object (OBJ) to the lens device (100), extending from the center of the lens device (100) outward.

[0087] The front surface (A1) of the first lens group (L1) may be curved.

[0088] At this time, if the front surface (A1) of the first lens group (L1) is formed as a flat or gently convex shape, it is advantageous for a small size, but there are limitations in terms of mechanical assembly and mass production, and it is difficult to reduce distortion. On the other hand, if the front surface (A1) of the first lens group (L1) is excessively convex, there is a limitation in that the size increases.

[0089] To solve this, the front surface (A1) of the first lens group (L1) is formed to be generally convex toward the object (OBJ) but at least a portion is concave, and the rear surface (B) of the first lens group may be concave toward the object (OBJ). In the present disclosure, "front" means the direction toward the object (OBJ), and "rear" may mean the direction toward the image sensing surface (IMG).

[0090] Specifically, the front surface (A1) of the first lens group (L1) is formed to be closer to the object (OBJ) from the outermost edge to a predetermined position in the direction of the center, but is inflected at said predetermined position so that the radially inner side is implemented to be further from the object (OBJ). That is, the front surface (A1) of the first lens group (L1) can be formed in a shape where the center is concave and the periphery is convex toward the object (OBJ).

[0091] With this configuration, the lens device (100) has the advantage of being able to be implemented in a small size and easy to manufacture.

[0092] In addition, the lens device (100) has the effect of being a wide-angle lens while minimizing distortion.

[0093] Meanwhile, the rear surface (B1) of the first lens group (L1) can be shaped such that the center area is closer to the object (OBJ) than the edge area. At this time, since the front surface (A1) and the rear surface (B1) are positioned on opposite sides of the first lens group (L1), the front surface (A1) of the first lens group (L1) can be described as "convex" toward the object (OBJ) and the rear surface (B1) of the first lens group (L1) can be described as "concave" toward the object (OBJ).

[0094]

[0095] Meanwhile, the front surface (A2) of the second lens group (L2) may be concave in the direction of the image sensing surface (IMG), and the rear surface (B2) of the second lens group (L2) may be convex in the direction of the image sensing surface (IMG).

[0096] That is, the front surface (A2) of the second lens group (L2) can be shaped such that the center area is closer to the image sensing surface (IMG) than the edge area. Additionally, the rear surface (B2) of the second lens group (L2) can also be shaped such that the center area is closer to the image sensing surface (IMG) than the edge area, just like the front surface (A2). At this time, since the front surface (A2) and the rear surface (B2) are positioned on opposite sides of the second lens group (L2), the front surface (A2) of the second lens group (L2) can be described as "concave" in the direction of the image sensing surface (IMG), and the rear surface (B2) of the second lens group (L2) can be described as "convex" in the direction of the image sensing surface (IMG).

[0097] Each front surface (A3, A5) of the third lens group (L3) and the fifth lens group (L5) may be convex toward the object, each rear surface (B3, B5) of the third lens group (L3) and the fifth lens group (L3) may be convex toward the image sensor, the front surface (A4) of the fourth lens group (L4) may be concave toward the image sensor, and the rear surface (B4) of the fourth lens group (L4) may be concave toward the object.

[0098] As described above, the first lens group (L1) to the fifth lens group (L5) can each be manufactured by injection molding using a plastic material. For example, the first lens group (L1), the third lens group (L3), and the fifth lens group (L5) can be manufactured using APEL APL5014CL (54620.560), and the second lens group (L2) and the fourth lens group (L4) can be manufactured using PANLITE SP-3810 (64610.230).

[0099] Below, before specifically describing the lens characteristics of the lens device (100), I will define the terms as follows.

[0100] - f: Compound focal length of the entire lens device (optical system)

[0101] - f0: Compound focal length of the front lens group

[0102] - f1: Focal length of the first lens group

[0103] - f2: Focal length of the second lens group

[0104] - GaF: Focal length of the front lens group

[0105] - H: Effective radius of the rear of the first lens group

[0106] - R1: Radius of curvature of the front surface of the first lens group

[0107] - R2: Radius of curvature of the rear surface of the first lens group

[0108] - Y: Distance on the image plane from the center of the formed image to the edge of the peak.

[0109] - L1BS: Length in the direction of the optical axis from the rear center point of the first lens group to the effective aperture position

[0110] - Ts: Distance from the front of the first lens group to the aperture

[0111] - TTL: Distance from the front of the first lens group to the sensing surface of the image sensor

[0112]

[0113] The lens device according to an embodiment of the present invention forms the rear surface of the second lens group (L2) in a convex shape so that the refractive power of the first lens group (L1) can be appropriately distributed, thereby improving performance while reducing distortion. In addition, it has the effect of enabling miniaturization suitable for endoscope lens devices.

[0114] To this end, the lens device of the present invention can satisfy the following Equation 1.

[0115] [Formula 1]

[0116] f2 / f > 1.6

[0117] When f2 / f is 1.6 or less, there is a limitation in that a wide depth of field cannot be secured.

[0118] In addition, preferably, a lens device according to one embodiment of the present invention can satisfy the following formula 1-1.

[0119] [Equation 1-1]

[0120] f2 / f ≥ 3.0

[0121] At this time, if f2 / f is below the lower limit, the distortion of the wide-angle lens increases and the focal length becomes longer, making it difficult to secure a wide depth of field.

[0122] In addition, a lens device according to one embodiment of the present invention can satisfy the following Equation 1-2.

[0123] [Equation 1-1]

[0124] 3 ≤ |f0 / f1| ≤ 5

[0125] If |f0 / f1| satisfies the range of Equation 1-2, the refractive power of the first lens is sufficiently distributed, enabling the realization of a wide angle while providing high performance.

[0126]

[0127] Meanwhile, since the lens device of the present invention is manufactured by an injection molding method, the rear surface (B1) of the first lens group (L1) can be formed in a curved shape. Accordingly, the aperture position of the wide-angle lens can be positioned in the middle of the optical axis direction to improve resolution, reduce distortion, and widen the depth of field.

[0128] Accordingly, the lens device of the present invention can satisfy the following Equation 2.

[0129] [Equation 2]

[0130] 0.25 < Ts / TTL < 0.7

[0131] Preferably, a lens device according to one embodiment of the present invention can satisfy the following Equation 2-1.

[0132] [Equation 2-1]

[0133] 0.4 < Ts / TTL < 0.6

[0134] If Ts / TTL is smaller than the lower limit, the aperture is positioned excessively forward, increasing the refractive power of the front lens group, which lowers resolution performance and increases distortion. Furthermore, if Ts / TTL exceeds the upper limit, the angle of the principal ray incident on the sensor increases, making application difficult; additionally, since the lens size of the front lens group must be increased, miniaturization is challenging.

[0135]

[0136] In addition, the lens device of the present invention can satisfy Equation 3.

[0137] [Equation 3]

[0138] L1BS / H < 1

[0139] Mass production is impossible if the shape angle (θ) exceeds 80 degrees at the effective diameter height of the rear surface (B1) of the first lens group (L1).

[0140] If L1BS / H exceeds the upper limit, the curvature shape of the rear surface (B) of the first lens group (L1) becomes close to a hemispherical shape, which reduces the injection moldability of the lens and causes the shape of the edge portion of the radius of curvature to deviate from the management standard, making it difficult to ensure quality.

[0141] When the lens device (100) is designed such that the above conditions (at least one of mathematical formulas 1 to 3) are satisfied, high-resolution optical performance can be achieved while reducing the lens size, even if the first lens group (L1) to the fifth lens group (L5) are each manufactured by injection molding with plastic material.

[0142]

[0143] In addition, the lens device of the present invention can satisfy Equation 4.

[0144] [Equation 4]

[0145] GaF / f < -1

[0146] When GaF / f exceeds the upper limit, the negative power (effective focal length, EFL) of the front lens group (FLG) becomes excessively large, placing a significant positive power burden on the rear lens group (RLG). The combination of strong negative power from the front lens group (FLG) and strong positive power from the rear lens group (RLG) increases the sensitivity of the optical system, which can reduce lens yield during mass production.

[0147]

[0148] In addition, the lens device of the present invention can satisfy Equation 5.

[0149] [Formula 5]

[0150] R2 / R1 < 0

[0151] If the front surface (A1) of the first lens group (L1) has a shape that is concave towards the center and convex towards the periphery, and the rear surface (B1) of the first lens group (L1) has a shape that is concave, then the above Equation 5 is satisfied.

[0152] Therefore, it has the effect of enabling miniaturization while simultaneously reducing distortion in wide-angle lenses.

[0153]

[0154] In addition, the lens device of the present invention can satisfy Equation 6.

[0155] [Equation 6]

[0156] Y / f > 1

[0157] When Y / f is less than 1, it is difficult to implement a wide-angle optical system, distortion increases, and depth of field becomes shallow, so it cannot function as an optical system.

[0158]

[0159] In addition, the lens device of the present invention can satisfy Equation 7 and Equation 8.

[0160] [Equation 7]

[0161] 15 < V2 <35

[0162] [Equation 8]

[0163] 20 < |V1-V2|

[0164] In this case, V1 may be the Abbe number (Vd) of the lens of the first lens group (L1), and V2 may be the Abbe number of the lens of the second lens group. The Abbe number is a measure of lens dispersion and can indicate the change in refractive index according to wavelength. In this case, the higher the Vd value, the lower the dispersion can be.

[0165] Meanwhile, in this embodiment, when |V1-V2| is 20 or less, the difference between the dispersion value of the first lens and the dispersion value of the second lens is small, so the resolution may be reduced.

[0166]

[0167] Meanwhile, embodiments applying the present invention are as shown in the following table.

[0168]

[0169] Figures 3a to 5 show lens data according to Example 1 of the lens device of the present invention of Figure 2, Figures 6a to 8 show lens data according to Example 2 of the lens device of the present invention of Figure 2, and Figures 9a to 11 show lens data according to Example 3 of the lens device of the present invention of Figure 2.

[0170] Hereinafter, with reference to FIGS. 3a to 11, lens data according to Example 1 of the lens device of the present invention satisfying Equations 1 to 8 will be described.

[0171] First, the description of Figs. 3a, 6a, and 9a is as follows.

[0172] The first column on the far left represents a plurality of surfaces related to the characteristics of the lens device (100). The plurality of surfaces may include an object surface (OBJ), a front surface (A1) and a rear surface (B1) of a first lens group (L1), a front surface (A2) and a rear surface (B2) of a second lens group (L2), an aperture surface (STO), a front surface (A3) and a rear surface (B3) of a third lens group (L3), a front surface (A4) and a rear surface (B4) of a fourth lens group (L4), a front surface (A5) and a rear surface (B5) of a fifth lens group (L5), and an image sensing surface (IMG).

[0173] The second column indicates the surface type, showing whether each face is spherical or aspherical.

[0174] The third column represents the radius of curvature on each face.

[0175] The fourth column indicates the thickness or interval from each surface to the next surface based on the above optical axis (OX). The unit is mm.

[0176] The fifth column indicates the refractive index of the lens corresponding to each face.

[0177] The sixth column represents the dispersion of the lens corresponding to each face.

[0178] Next, the description of Figs. 3b, 6b, and 9b is as follows.

[0179] The first column on the far left represents a plurality of surfaces related to the characteristics of the lens device (100). The plurality of surfaces may include a front surface (A1) and a rear surface (B1) of a first lens group (L1), a front surface (A2) and a rear surface (B2) of a second lens group (L2), an aperture surface (STO), a front surface (A3) and a rear surface (B3) of a third lens group (L3), a front surface (A4) and a rear surface (B4) of a fourth lens group (L4), and a front surface (A5) and a rear surface (B5) of a fifth lens group (L5).

[0180] In addition, the aspheric coefficients (K, A4, A6, A8, A10, A12, A14) for the aspheric equation are indicated in parentheses. The aspheric equation is as shown in Equation 9 below.

[0181] [Formula 9]

[0182]

[0183] Here, Z is the distance from the vertex of the lens in the direction of the optical axis, h is the distance perpendicular to the optical axis of the lens surface, C is the reciprocal of the radius of curvature at the vertex of the lens, K is the Conic constant, and A4, A6, A8, A10, A12, and A14 are the aspherical coefficients, respectively.

[0184]

[0185] FIGS. 4, FIGS. 7, and FIGS. 10 illustrate aberration diagrams of the first to fifth lights (F1 to F5) for Examples 1 to 3.

[0186] FIGS. 4, FIGS. 7, and FIGS. 10 show aberration diagrams for the tangential plane and sagittal plane of the first to fifth lights (F1 to F5) in each embodiment.

[0187] FIGS. 5, FIGS. 8, and FIGS. 11 illustrate spherical aberration, astigmatism, and distortion for Examples 1 to 3.

[0188] The leftmost part of Fig. 5 is spherical aberration, which indicates the degree to which the focal positions of paraxial and pyraxial light traveling parallel to the optical axis, which is the center of the lens, differ.

[0189] The center of Figure 5 represents astigmatism, which indicates the degree of focus deviation between the tangential plane and the sagittal plane when light originating from the off-axis passes through the lens.

[0190] The right side of Fig. 5 shows distortion, indicating the degree of magnification that varies depending on the field of view (FOV) area.

[0191]

[0192] Although the present invention has been described in detail through specific embodiments, this is for the purpose of specifically explaining the invention and is not limited thereto. It is evident that modifications or improvements to the present invention are possible by those skilled in the art within the technical scope of the invention.

[0193] All simple variations or modifications of the present invention fall within the scope of the present invention, and the specific scope of protection of the present invention will be clarified by the appended claims.

Claims

1. Includes a front lens group, an aperture, and a rear lens group arranged sequentially from the object direction to the image sensor direction, and The above-mentioned front lens group has a negative refractive power overall, and The above rear lens group has a positive refractive power overall, and The above front lens group, A first group of lenses having negative refractive power; A second lens group having positive refractive power, with a rear surface convex toward the image sensor; Includes, Let f be the total focal length including the front lens group, the aperture, and the rear lens group, and let f2 be the focal length of the second lens group, Lens device satisfying f2 / f > 1.

6.

2. In Paragraph 1, A lens device characterized in that at least a portion of the front surface of the first lens group is concave.

3. In Paragraph 1, A lens device characterized in that the first lens group is formed of a plastic material.

4. In Paragraph 1, The above rear lens group has a third lens group, a fourth lens group, and a fifth lens group arranged sequentially in the direction from the object toward the image sensor, and A lens device characterized by the above-mentioned fourth lens group having negative refractive power.

5. In Paragraph 4, A lens device characterized in that the third lens group and the fifth lens group each have a positive refractive power.

6. In Paragraph 4, A lens device characterized in that the above-mentioned fifth lens group is formed of a plastic material.

7. In Paragraph 4, At least one of the front and rear surfaces of the first to fifth lens groups is, A lens device characterized by being aspherical.

8. In Paragraph 1, Let H be the effective radius of the rear surface of the first lens group, and L1BS be the length in the direction of the optical axis from the center point of the rear surface of the first lens group to the position of the effective aperture, Lens device satisfying L1BS / H < 0.

8.

9. In Paragraph 1, Let Ts be the distance from the front of the first lens group to the aperture, and TTL be the distance from the front of the first lens group to the sensing surface of the image sensor, A lens device characterized by satisfying 0.25 < Ts / TTL < 0.

7.

10. In Paragraph 1, Let Ts be the distance from the front of the first lens group to the aperture, and TTL be the distance from the front of the first lens group to the sensing surface of the image sensor, A lens device characterized by satisfying 0.4 < Ts / TTL < 0.

6.

11. In Paragraph 1, When the focal length of the above-mentioned front lens group is denoted as GaF, A lens device characterized by satisfying GaF / f < -1.

12. In Paragraph 1, When the radius of curvature of the front surface of the first lens group is denoted as R1 and the radius of curvature of the rear surface of the first lens group is denoted as R2, A lens device characterized by satisfying R2 / R1 < 0.

13. In Paragraph 1, When Y is the distance on the image plane from the center of the formed image to the edge of the peak, A lens device characterized by satisfying Y / f > 1.

14. In Paragraph 1, When the Abbe number of the lens of the second lens group above is denoted as V2, A lens device characterized by satisfying 15 < V2 < 35.

15. In Paragraph 1, When the Abbe number of the lens of the first lens group is V1 and the Abbe number of the second lens group is V2, A lens device characterized by satisfying 20 < |V1-V2|.

16. In Paragraph 1, Lens device satisfying f2 / f ≥ 3.0.

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