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EP-4303636-B1 - LENS SYSTEM, OPTICAL FINGERPRINT RECOGNITION APPARATUS, AND TERMINAL DEVICE

EP4303636B1EP 4303636 B1EP4303636 B1EP 4303636B1EP-4303636-B1

Inventors

  • TSAI, FEI HSIN
  • XU, Baiwei
  • GE, Cong

Dates

Publication Date
20260506
Application Date
20210913

Claims (13)

  1. A lens system (10) for an optical fingerprint recognition apparatus, which is arrangable under a display screen to realize under-display optical fingerprint detection, the lens system comprising: a first lens (11), a stop, a second lens (12), and a third lens (13) sequentially arranged from an object side to an image side; wherein the first lens (11) is a biconcave lens having a negative refractive power; the second lens (12) is a biconvex lens having a positive refractive power; and the third lens (13) is a lens having a positive refractive power, wherein an object side surface of the third lens (13) is a convex surface, and parameters of the lens system (10) satisfy a first relationship: -0.7 mm < f1*f3/TTL < -0.15 mm, wherein f1 is a focal length of the first lens (11), f3 is a focal length of the third lens (13), and TTL is a distance from a lower surface of the display screen (20) to an upper surface of an image sensor (402) which is included in the optical fingerprint recognition apparatus and arranged under the lens system (10); the parameters of the lens system (10) satisfy fourth relationships, and the fourth relationships comprise: 0.4 < CT1/CT2 < 0.6 and 1.7 < CT2/CT3 < 2.0, wherein CT1 is a thickness of the first lens (11) along its optical axis direction, CT2 is a thickness of the second lens (12) along its optical axis direction, and CT3 is a thickness of the third lens (13) along its optical axis direction.
  2. The lens system according to claim 1, wherein the parameters of the lens system satisfy at least one relationship among second relationships, and the second relationships comprise: - 1.6<f1/f2<-0.6, 0.2<f2/f3<1.2, -1.7<f1/f12<-0.4, 0.5<f2/f12<1.2, 1.2<f2/f23<1.9, 1.5<f3/f23<3.7, 1.2<f12/f23<2.7, 1.5<f12/f<3.8, and 1<f23/f<1.6, wherein wherein f is a focal length of the lens system, f2 is a focal length of the second lens, f12 is a combined focal length of the first lens and the second lens, and f23 is a combined focal length of the second lens and the third lens.
  3. The lens system according to claim 1 or 2, wherein the parameters of the lens system satisfy at least one relationship among third relationships, and the third relationships comprise: -1.2<r1/r2<-0.2, -2.7<r3/r4<-1.9, and -0.2<r5/r6<0.5, wherein r1 is a curvature radius of an object side surface of the first lens, r2 is a curvature radius of an image side surface of the first lens, r3 is a curvature radius of an object side surface of the second lens, r4 is a curvature radius of an image side surface of the second lens, r5 is a curvature radius of the object side surface of the third lens, and r6 is a curvature radius of an image side surface of the third lens.
  4. The lens system according to any one of claims 1 to 3, wherein the first lens in the lens system satisfies: 0.7<f1/r1<1.4 and -1.1<f1/r2<-0.3, wherein f1 is the focal length of the first lens, r1 is the curvature radius of the object side surface of the first lens, and r2 is the curvature radius of the image side surface of the first lens.
  5. The lens system according to any one of claims 1 to 3, wherein the second lens in the lens system satisfies 0.4<f2/r3<0.8 and -1.6<f2/r4<-1.2, wherein f2 is the focal length of the second lens, r3 is the curvature radius of the object side surface of the second lens, and r4 is the curvature radius of the image side surface of the second lens.
  6. The lens system according to any one of claims 1 to 3, wherein the third lens in the lens system satisfies: 1.4<f3/r5<3.0 and -0.3<f3/r6<1.3, wherein f3 is the focal length of the third lens, r5 is the curvature radius of the object side surface of the third lens, and r6 is the curvature radius of the image side surface of the third lens.
  7. The lens system according to any one of claims 1 to 3, wherein the lens system has a FOV of greater than 100 degrees.
  8. The lens system according to any one of claims 1 to 3, wherein the lens system has an F-number of less than 2.0, and has a distortion of less than 5%.
  9. The lens system according to any one of claims 1 to 3, wherein the image side surface of the third lens is a convex surface or a concave surface.
  10. An optical fingerprint recognition apparatus, comprising: the lens system according to any one of claims 1 to 9.
  11. The optical fingerprint recognition apparatus according to claim 10, wherein the optical fingerprint recognition apparatus further comprises: a bracket, wherein the lens system is interference-fitted in the bracket; an image sensor arranged under the lens system for receiving a fingerprint light signal converged by the lens system, and processing the fingerprint light signal to acquire fingerprint information included in the fingerprint light signal; and an infrared filter arranged as a filter film layer formed on a surface of the image sensor.
  12. A terminal device, comprising: a display screen and the optical fingerprint recognition apparatus according to claim 10 or 11, wherein the optical fingerprint recognition apparatus is arranged under the display screen.
  13. The terminal device according to claim 12, wherein the terminal device further comprises: a foam and a copper foil arranged under the display screen, wherein the foam and the copper foil each have an opening, and the opening of the foam and the opening of the copper foil correspond to top of the lens system of the optical fingerprint recognition apparatus, such that a fingerprint light signal including fingerprint information enters the lens system.

Description

TECHNICAL FIELD Embodiments of the present disclosure relate to the field of optical imaging, and more particularly relate to a lens system, an optical fingerprint recognition apparatus, and a terminal device. BACKGROUND In order to improve user experience, a high screen ratio has become a goal pursued by manufacturers of mobile phones or other terminal devices at present. Since fingerprint information is collected using an under-display optical fingerprint recognition technology based on an optical imaging principle, fingerprint recognition can be realized simply by arranging a fingerprint recognition module under a display screen of a terminal device without occupying a display region of the display screen, so that the under-display optical fingerprint recognition technology has become a mainstream technology. However, with the increasing diversification and specialization of mobile phone functions, various functional modules of a mobile phone have an increasing demand for an internal space of the mobile phone, and an existing optical fingerprint recognition module has a large size in a direction perpendicular to the display screen, thereby restricting the development of thin and light mobile phones. WO2021/128564A1 is directed to an optical lens, which sequentially comprises, along an optical axis from an object side to an image side: flat glass; a first lens having negative focal power; a stop ; a second lens having positive focal power; a third lens having positive focal power; and an infrared filter. The first lens has a convex object-side surface proximate to the optical axis, at least one inflection point, and a concave image-side surface; the second lens has a convex object-side surface, and a convex image-side surface; and the third lens has a convex image-side surface. The optical lens can improve fingerprint recognition rate of the user and reduce production costs, and are suitable for the design requirements of a mobile phone full screen. CN208888461U is directed to lens system. The system comprises a first lens and a second lens which are sequentially arranged from an object space to an image space, wherein the first lens is a meniscus lens with negative focal power, the object side of the meniscus lens is a concave surface, the second lens is a lens with positive focal power, the object side and the image plane side of the second lens are both convex surfaces, and the third lens is a lens with positive focal power, and the object side and the image plane side of the third lens are both convex surfaces; Moreover, the parameters of the lens system satisfy a first relationship such that a field angle FOV of the lens system is greater than a first threshold value. US20160205297A1 is a compact optical system includes, in order from an object side to an image side, a first lens element, a second lens element and a third lens element. The first lens element with negative refractive power has an image-side surface being concave in a paraxial region thereof. The second lens element has refractive power, wherein at least one of two surfaces of the second lens element is aspheric, and the second lens element is made of plastic material. The third lens element has positive refractive power, wherein at least one of two surfaces of the third lens element is aspheric, and the third lens element is made of plastic material. The compact optical system further comprises a stop located between the first lens element and the second lens element. The first, second, and third lens elements are all stationary relative to one another in a paraxial region. CN111694134A is directed to an image capturing lens comprising, in order from an object side to an image side: a first lens element with negative refractive power; a second lens element with positive refractive power; a third lens element with positive refractive power; the image capturing lens satisfies the following relational expressions: SD11/sin (ANG12) is greater than 2.50 mm and less than 5.20mm, wherein SD11 is the height of the maximum effective diameter of the object side surface of the first lens relative to the optical axis, and ANG12 is the included angle between the tangent line of the curved surface of the image side surface of the first lens at the maximum effective diameter and the vertical line of the optical axis. CN112782835A is directed to an optical imaging lens. The optical imaging lens includes, in order along an optical axis from an object side to an image side : a first lens having negative power, an object side being a concave surface and an image side being a concave surface; A second lens with positive focal power having a convex object side and a convex image side; And a third lens having a positive power, the object side of which is a convex surface. The total effective focal length f of the optical imaging lens and the entrance pupil diameter EPD of the optical imaging lens satisfy: f/EPD is less than 1.5; and the maximum field angle