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EP-4293407-B1 - IMAGING SYSTEM LENS ASSEMBLY, IMAGING APPARATUS AND ELECTRONIC DEVICE

EP4293407B1EP 4293407 B1EP4293407 B1EP 4293407B1EP-4293407-B1

Inventors

  • CHUANG, YI-HSIANG
  • HUANG, HSIN-HSUAN
  • TSAI, CHENG-YU

Dates

Publication Date
20260506
Application Date
20230228

Claims (11)

  1. An imaging system lens assembly, characterized in comprising four lens elements (E1, E2, E3, E4), the four lens elements (E1, E2, E3, E4) being, in order from an object side to an image side along an optical path: a first lens element (E1), a second lens element (E2), a third lens element (E3) and a fourth lens element (E4); each of the four lens elements (E1, E2, E3, E4) has an object-side surface towards the object side and an image-side surface towards the image side; wherein the second lens element (E2) has negative refractive power, the object-side surface of the second lens element (E2) is concave in a paraxial region thereof; the object-side surface of the third lens element (E3) is convex in a paraxial region thereof; wherein a total number of the lens elements of the imaging system lens assembly is four; the imaging system lens assembly further comprises an aperture stop (ST), an axial distance between the aperture stop (ST) and the image-side surface of the fourth lens element (E4) is SD, a curvature radius of the object-side surface of the second lens element (E2) is R3, a curvature radius of the image-side surface of the second lens element (E2) is R4, an axial distance between the object-side surface of the first lens element (E1) and the image-side surface of the fourth lens element (E4) is TD, an axial distance between the image-side surface of the fourth lens element (E4) and an image surface (IMG) is BL, a sum of all axial distances between adjacent lens elements of the imaging system lens assembly is ΣAT, a sum of all central thicknesses of the four lens elements (E1, E2, E3, E4) of the imaging system lens assembly is ΣCT, a focal length of the first lens element (E1) is f1, a focal length of the second lens element (E2) is f2, a focal length of the third lens element (E3) is f3, a focal length of the fourth lens element (E4) is f4, and the following conditions are satisfied: R 3 + R 4 / R 3 − R 4 < 0 ; 0.1 < SD / TD < 2.0 ; 0.1 < TD / BL < 1.0 ; 0.04 < ΣAT / ΣCT < 0.8 ; 0 < f 2 / f 4 < 1.4 ; and 0.18 < f 1 / f 3 + f 1 / f 4 < 1.75 ; characterized in that the image-side surface of the third lens element (E3) is concave in a paraxial region thereof.
  2. The imaging system lens assembly of claim 1, wherein the first lens element (E1) has positive refractive power, the object-side surface of the first lens element (E1) is convex in a paraxial region thereof.
  3. The imaging system lens assembly of claim 1 or claim 2, wherein half of a maximum field of view of the imaging system lens assembly is HFOV, and the following condition is satisfied: 5.0 degrees < HFOV < 20.5 degrees .
  4. The imaging system lens assembly of any one of claims 1-3, wherein there is an air gap between each of adjacent lens elements of the four lens elements (E1, E2, E3, E4) of the imaging system lens assembly, a central thickness of the first lens element (E1) is CT1, a central thickness of the fourth lens element (E4) is CT4, and the following condition is satisfied: 0.1 < CT 4 / CT 1 < 0.8 .
  5. The imaging system lens assembly of any one of claims 1-4, wherein a focal length of the imaging system lens assembly is f, the focal length of the second lens element (E2) is f2, and the following condition is satisfied: − 10.5 < f / f 2 < − 0.75 .
  6. The imaging system lens assembly of any one of claims 1-5, wherein an Abbe number of the second lens element (E2) is V2, an Abbe number of the fourth lens element (E4) is V4, and the following condition is satisfied: 0.01 < V 4 / V 2 < 2.5 .
  7. The imaging system lens assembly of any one of claims 1-6, wherein at least one of the object-side surface and the image-side surface of at least one of the four lens elements (E1, E2, E3, E4) comprises at least one inflection point.
  8. The imaging system lens assembly of any one of claims 1-7, further comprising: a reflective element disposed between an imaged object (206) and the image surface (IMG).
  9. The imaging system lens assembly of claim 8, wherein the reflective element is disposed at an object side of the object-side surface of the first lens element (E1) or at an image side of the image-side surface of the fourth lens element (E4).
  10. An imaging apparatus (1), characterized in comprising: the imaging system lens assembly of any one of claims 1-9; and an image sensor (IS) disposed on the image surface (IMG) of the imaging system lens assembly.
  11. An electronic device, characterized in comprising: the imaging apparatus (1) of claim 10.

Description

BACKGROUND Technical Field The present disclosure relates to an imaging system lens assembly and an imaging apparatus. More particularly, the present disclosure relates to an imaging system lens assembly and an imaging apparatus with compact size applicable to electronic devices. Description of Related Art With recent technology of semiconductor process advances, performances of image sensors are enhanced, so that the smaller pixel size can be achieved. Therefore, optical lens assemblies with high image quality have become an indispensable part of many modern electronics. With rapid developments of technology, applications of the electronic devices equipped with optical lens assemblies become wider, and there is a bigger variety of requirements for the optical lens assemblies. However, in a conventional optical lens assembly, it is hard to balance among image quality, sensitivity, aperture size, volume or field of view. In recent years, with the demands of compact electronic devices, conventional photographing lens assembly is unable to satisfy both requirements of high-end specification and compactness, especially the micro lens assembly with a large aperture stop or a telephoto feature. Because the requirements of the optical zoom become higher (such as increasing the optical zoom ratio), the conventional telephoto lens assemblies cannot satisfy the requirements (due to the excessive total track length, the small aperture stop, the poor image quality or lacking of compactness), so that the arrangements with different optical properties or the ability to fold the optical axis are needed. In order to solve the aforementioned technical problems and demands, an optical lens assembly is provided in the present disclosure to meet the requirements. CN212229309U presents an optical imaging lens designed to work effectively with a liquid lens, aiming to overcome issues like difficult installation, low yield, and large size in existing designs. The lens structure consists of a stop followed by only four lenses (L1, L2, L3, L4) in sequence from the object side, where L1, L3, and L4 have positive refractive power and L2 has negative refractive power, with specific surface shapes and focal length ratios. SUMMARY According to the present disclosure, an imaging system lens assembly according to claim 1 is provided. Preferred embodiments are defined by the dependent claims. The remaining examples included in this section of the description up until the heading "BRIEF DESCRIPTION OF THE DRAWINGS" are not according to the claims. According to the present disclosure, an imaging system lens assembly includes four lens elements, the four lens elements are, in order from an object side to an image side along an optical path: a first lens element, a second lens element, a third lens element and a fourth lens element. Each of the four lens elements has an object-side surface towards the object side and an image-side surface towards the image side. The second lens element preferably has negative refractive power, the object-side surface of the second lens element preferably is concave in a paraxial region thereof. The object-side surface of the third lens element preferably is convex in a paraxial region thereof, the image-side surface of the third lens element preferably is concave in a paraxial region thereof. There preferably is an air gap between each of adjacent lens elements of the four lens elements of the imaging system lens assembly. The imaging system lens assembly preferably further includes an aperture stop. When an axial distance between the aperture stop and the image-side surface of the fourth lens element is SD, a curvature radius of the object-side surface of the second lens element is R3, a curvature radius of the image-side surface of the second lens element is R4, an axial distance between the object-side surface of the first lens element and the image-side surface of the fourth lens element is TD, an axial distance between the image-side surface of the fourth lens element and an image surface is BL, an axial distance between the first lens element and the second lens element is T12, an axial distance between the second lens element and the third lens element is T23, a focal length of the second lens element is f2, a focal length of the fourth lens element is f4, a central thickness of the first lens element is CT1, a central thickness of the third lens element is CT3, and a central thickness of the fourth lens element is CT4, the following conditions preferably are satisfied: (R3+R4)/(R3-R4) < 0; 0.1 < SD/TD < 2.0; 0.1 < TD/BL < 1.0; 0.01 < T23/T12 < 30.0; 0 < |f2/f4| < 0.95; and 0.1 < (CT3+CT4)/CT1 < 1.5. According to the aforementioned imaging system lens assembly, when half of a maximum field of view of the imaging system lens assembly is HFOV, the following condition can be satisfied: 5.0 degrees < HFOV < 20.5 degrees. According to the aforementioned imaging system lens assembly, when an f-number of the i