US-20260126620-A1 - OPTICAL SYSTEM AND CAMERA MODULE COMPRISING SAME

US20260126620A1US 20260126620 A1US20260126620 A1US 20260126620A1US-20260126620-A1

Abstract

An optical system according to an embodiment includes first to third lenses disposed along an optical axis from an object side to a sensor side direction, wherein the first lens has a meniscus shape convex toward the object side, and satisfies 1.7≤nt_ 1 ≤2.3 and TTL≤6 mm. (nt_ 1 is the refractive index of the first lens with respect to the light of the t-line wavelength band, and TTL is the distance on the optical axis from the object-side surface of the first lens to the upper surface of the image sensor.)

Inventors

Chang Gyun Son
Ki Cheol Kim
Jun Young Lim

Assignees

LG INNOTEK CO., LTD.

Dates

Publication Date: 20260507
Application Date: 20251231
Priority Date: 20210209

Claims (20)

1 . An optical system consisting of: first to third lenses arranged along an optical axis from an object side toward an image side, wherein the first lens has a positive refractive power, wherein the second lens has a positive refractive power, wherein an object-side surface of the first lens has a convex shape toward the object side, wherein the first lens has a highest refractive index among the first to third lenses, wherein the first lens is made of glass material, and the second and third lenses are made of plastic material, and wherein an effective diameter of the object-side surface of the first lens is shorter than an effective diameter of an image-side surface of the third lens.
2 . An optical system consisting of: first to third lenses arranged along an optical axis from an object side toward a sensor side where an image sensor is disposed, wherein the first lens has a positive refractive power, wherein the second lens has a positive refractive power, wherein an object-side surface of the first lens has a convex shape toward the object side, wherein the first lens is made of glass material, and the second and third lenses are made of plastic material, and wherein an effective diameter of the object-side surface of the first lens is shorter than a diagonal length of the image sensor.
3 . The optical system of claim 1 , wherein an object-side surface of the third lens is convex toward the object side.
4 . The optical system of claim 2 , wherein a focal length of the first lens is shorter than a focal length of the second lens.
5 . The optical system of claim 1 , wherein an effective diameter of an image-side surface of the first lens is shorter than an effective diameter of an object-side surface of the second lens.
6 . The optical system of claim 2 , wherein an effective diameter of a sensor-side surface of the first lens is shorter than an effective diameter of an object-side surface of the second lens.
7 . The optical system of claim 1 , wherein a surface with the largest absolute value of a radius of curvature among object-side and image-side surfaces of the first to third lenses is the object-side surface of the second lens.
8 . The optical system of claim 1 , wherein a focal length of the first lens is shorter than a focal length of the second lens.
9 . The optical system of claim 1 , wherein a focal length of the first lens is the shortest among the first through third lenses.
10 . The optical system of claim 1 , wherein an effective diameter of an image-side surface of the first lens is CA_L 1 S 2 , wherein an effective diameter of an object-side surface of the second lens is CA_L 2 S 1 , wherein an effective diameter of an object-side surface of the third lens is CA_L 3 S 1 , and wherein the following condition is satisfied: CA_L 1 S 2 ≤CA_L 2 S 1 ≤CA_L 3 S 1 .
11 . The optical system of claim 2 , wherein an effective diameter of a sensor-side surface of the first lens is CA_L 1 S 2 , wherein an effective diameter of an object-side surface of the second lens is CA_L 2 S 1 , wherein an effective diameter of an object-side surface of the third lens is CA_L 3 S 1 , and wherein the following condition is satisfied: CA_L 1 S 2 ≤CA_L 2 S 1 ≤CA_L 3 S 1 .
12 . The optical system of claim 2 , wherein an effective diameter of a sensor-side surface of the first lens is CA_L 1 S 2 , wherein an effective diameter of an object-side surface of the second lens is CA_L 2 S 1 , wherein an effective diameter of a sensor-side surface of the second lens is CA_L 2 S 2 , wherein an effective diameter of an object-side surface of the third lens is CA_L 3 S 1 , wherein an effective diameter of a sensor-side surface of the third lens is CA_L 3 S 2 , wherein the diagonal length of the image sensor is ImgH, wherein the following condition is satisfied: CA_L 1 S 2 ≤CA_L 2 S 1 ≤CA_L 2 S 2 ≤CA_L 3 S 1 ≤CA_L 3 S 2 <ImgH.
13 . The optical system of claim 2 , wherein a surface with the smallest absolute radius of curvature among object-side and sensor-side surfaces of the first to third lens is the object-side surface of the third lens or the sensor-side surface of the third lens.
14 . The optical system of claim 1 , wherein a refractive power of the third lens is positive.
15 . The optical system of claim 1 , wherein the third lens has the longest focal length among focal lengths of the first through third lenses.
16 . A camera module comprising: an optical system; and an image sensor, wherein the optical system comprises first to third lenses arranged along an optical axis from an object side to a sensor side, wherein a refractive power of the first lens is positive, wherein a refractive power of the second lens is positive, wherein an object-side surface of the first lens is convex toward the object side, wherein the first lens has the highest refractive index among the first through third lenses, wherein the first lens is made of glass material, wherein an effective diameter of a sensor-side surface of the first lens is the shortest among effective diameters of object-side and sensor-side surfaces of the first to third lenses, and wherein a diagonal length of the sensor is greater than the effective diameters of the object-side and sensor-side surfaces of the first to third lenses.
17 . The optical system of claim 16 , wherein the object-side surface of the third lens is convex toward the object side.
18 . The optical system of claim 16 , wherein the effective diameter of the sensor-side surface of the first lens is shorter than the object-side effective diameter of the second lens.
19 . The optical system of claim 16 , wherein a surface with the largest absolute value of a radius of curvature among object-side and sensor-side surfaces of the first to third lens is the object-side surface of the second lens.
20 . The optical system of claim 16 , wherein a focal length of the first lens among focal lengths of the first to third lenses is the shortest.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation of U.S. Application No. Ser. No. 18/264,682, filed Aug. 8, 2023; which is the U.S. national stage application of International Patent Application No. PCT/KR2022/001987, filed Feb. 9, 2022, which claims the benefit under 35 U.S.C. § 119 of Korean Application Nos. 10-2021-0018549, filed Feb. 9, 2021; 10-2021-0091809, filed Jul. 13, 2021; 10-2021-0177903, filed Dec. 13, 2021; and 10-2021-0183195, filed Dec. 20, 2021; the disclosures of each of which are incorporated herein by reference in their entirety. TECHNICAL FIELD An embodiment relates to an optical system having improved optical performance and a camera module comprising the same. BACKGROUND ART ADAS (Advanced Driving Assistance System) is an advanced driver assistance system to assist drivers in driving. ADAS is configured to sense the situation in front, determine the situation based on the sensed result, and control the behavior of the vehicle based on the situation determination. For example, the ADAS sensor device detects a vehicle ahead and recognizes a lane. Then, when the target lane or target speed and the target in front are determined, the vehicle's ESC (Electrical Stability Control), EMS (Engine Management System), MDPS (Motor Driven Power Steering), etc. are controlled. Typically, ADAS may be implemented as an automatic parking system, a low-speed city driving assistance system, a blind spot warning system, or the like. Sensor devices for detecting the situation ahead in ADAS include a GPS sensor, a laser scanner, a front radar, and a lidar, and the most representative is a camera for photographing the front, rear and side of the vehicle. Such a camera may be disposed outside or inside the vehicle to sense surrounding conditions of the vehicle. In addition, the camera may be disposed inside the vehicle to detect the situation of the driver and the passenger. For example, the camera may photograph the driver at a position adjacent to the driver, and may detect the driver's health state, whether he is drowsy, whether he is drinking, or the like. In addition, the camera may photograph the passenger at a position adjacent to the passenger, detect whether the passenger is sleeping, health status, etc., and may provide information about the passenger to the driver. In particular, the most important element for obtaining an image in a camera is an imaging lens that forms an image. Recently, interest in high performance such as high image quality and high resolution is increasing, and research on an optical system including a plurality of lenses is being conducted in order to realize this. However, when the camera is exposed to a harsh environment, for example, high temperature, low temperature, moisture, high humidity, etc. outside or inside the vehicle, there is a problem in that the characteristics of the optical system change. In this case, the camera has a problem in that it is difficult to uniformly derive excellent optical characteristics and aberration characteristics. Therefore, a new optical system and a camera capable of solving the above problems are required. DISCLOSURE Technical Problem An embodiment is to provide an optical system and a camera module with improved optical properties. In addition, the embodiment is to provide an optical system and a camera module that can provide excellent optical properties in a low or high temperature environment. In addition, embodiment is to provide an optical system and a camera module capable of inhibiting or minimizing changes in optical properties in various temperature ranges. Technical Solution An optical system according to an embodiment includes first to third lenses disposed along an optical axis from an object side to a sensor side direction, wherein the first lens has a meniscus shape convex toward the object side, and satisfies 1.7≤nt_1≤2.3 and TTL≤6 mm. (nt_1 is the refractive index of the first lens with respect to the light of the t-line wavelength band, and TTL is the distance on the optical axis from the object-side surface of the first lens to the upper surface of the image sensor.) In addition, the object-side surface and the sensor-side surface of the first lens may be spherical. In addition, 1.4 mm≤D_1 may be satisfied. (D_1 is the thickness on the optical axis of the first lens.) Also, a difference between the Abbe numbers of the first to third lenses may be 10 or less. In addition, the F-number of the optical system may be 1.8 to 2.2. Also, nt_2<nt_1, nt_3<nt_1 may be satisfied, materials of the first lens and the second lens are different from each other, materials of the first lens and the third lens are different from each other, and materials of the second lens and the third lens may be the same. (nt_1 is the refractive index of the first lens with respect to the light of the t-line wavelength band, nt_2 is the refractive index of the second lens with respect to the light of the t-line wavelength