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CN-121995605-A - Long-focus optical projection assembly

CN121995605ACN 121995605 ACN121995605 ACN 121995605ACN-121995605-A

Abstract

The invention provides a long-focal-length optical projection assembly, which consists of a diaphragm and a plurality of lenses from an object side to an image side, wherein the lenses are a first lens with positive focal power, a second lens with negative focal power, a third lens with positive focal power, a fourth lens with positive focal power and a fifth lens with negative focal power, the object side of the first lens is an aspheric surface, the second lens is a biconcave lens, the third lens is a meniscus lens with a concave surface facing the object side, the two side surfaces of the fourth lens and the fifth lens are aspheric surfaces, distortion is controlled to be at a minimum level (< 0.2%) through specific focal power distribution, the projection image and a real scene are ensured to be accurately fused, meanwhile, different material combinations are adopted in related lenses to realize full-band apochromatic aberration of visible light, color ghost images are eliminated, and the reduction degree of image display is improved.

Inventors

  • MAO HAOYANG
  • ZHANG LIZHI
  • Duan Fanlin
  • LU QIUPING
  • YAO MINGYAN
  • YU JUN

Assignees

  • 宁波永新光学股份有限公司

Dates

Publication Date
20260508
Application Date
20260409

Claims (8)

  1. 1. The utility model provides a long focal length optical projection subassembly, is constituteed by diaphragm and a plurality of lens from object side to image side, its characterized in that, a plurality of lenses be positive focal power's first lens, negative focal power's second lens, positive focal power's third lens, positive focal power's fourth lens and negative focal power's fifth lens, first lens's object side be the aspheric surface, second lens be biconcave lens, third lens be concave surface towards object side's meniscus lens, fourth lens and fifth lens's both sides surface be the aspheric surface, third lens's image side radius of curvature R32 and fourth lens's object side radius of curvature R41 satisfy: -1.3 < R32/R41 < 0.9, the focal length f of the long focal length optical projection assembly, the focal length f1 of the first lens, the focal length f2 of the second lens, the focal length f3 of the third lens, the focal length f4 of the fourth lens and the focal length f5 of the fifth lens satisfying 45mm < f <65mm,0.8< f1/f <1.0, -0.6< f2/f < 0.3,0.7< f3/f <2.1,0.5< f4/f <0.7, -0.8< f5/f < 0.5, the Abbe number Vd4 of the fourth lens and the Abbe number Vd5 of the fifth lens satisfying 30< Vd4-Vd5<45.
  2. 2. The long-focus optical projection assembly of claim 1 wherein both side surfaces of the second lens and the third lens are aspheric.
  3. 3. The long-focus optical projection assembly of claim 1 wherein the object-side radius of curvature R41 of the fourth lens element, the image-side radius of curvature R42 of the fourth lens element, the object-side radius of curvature R51 of the fifth lens element and the image-side radius of curvature R52 of the fifth lens element satisfy 0.3-1.0,0.1-0.5.
  4. 4. The long-focus optical projection assembly of claim 1 wherein the total optical length TTL of the long-focus optical projection assembly satisfies 90mm < TTL <120mm.
  5. 5. The long-focal length optical projection assembly according to any one of claims 1 to 4, wherein the first lens is a cemented lens composed of a first single lens of negative power, a second single lens of positive power, and a third single lens of negative power, and the focal length f11 of the first single lens, the focal length f12 of the second single lens, and the focal length f13 of the third single lens satisfy-16.5 < f11/f1< -11.5, 0.5< f12/f1<0.7, -2.0< f13/f1< -1.8.
  6. 6. The long-focus optical projection assembly of claim 5 wherein Abbe number Vd11 of said first single lens, abbe number Vd12 of said second single lens and Abbe number Vd13 of said third single lens satisfy 13< Vd11-Vd12<15,23< Vd12-Vd13<26.
  7. 7. The long-focal length optical projection assembly according to any one of claims 1 to 4, wherein the first lens is a cemented doublet lens composed of a fourth single lens of positive power and a fifth single lens of negative power, and a focal length f14 of the fourth single lens and a focal length f15 of the fifth single lens satisfy 0.5< f14/f1<0.7, -1.8< f15/f1< -1.3.
  8. 8. The long-focus optical projection assembly of claim 7 wherein the abbe number Vd14 of the fourth single lens and the abbe number Vd15 of the fifth single lens satisfy 19< vd14-Vd15<23.

Description

Long-focus optical projection assembly Technical Field The present invention relates to an optical projection assembly, and more particularly, to a long focal length optical projection assembly. Background In order to realize the accurate fusion of the virtual image and the road environment, the optical projection assembly needs to be matched with a far-field vision adjusting mechanism of human eyes through virtual image remodelling, and the perception requirement of high-order automatic driving is met. On one hand, in order to avoid distraction and potential safety hazards caused by frequent switching of the sight focus of a driver due to too close virtual images, the optical projection assembly must have a longer focal length to project the virtual images to a far-field area outside the windshield, and on the other hand, in order to match the perception requirement of L3/L4 level automatic driving, the virtual image display distance must be extended from the vehicle state information in a traditional several meters to advanced driving assistance system (English: ADVANCED DRIVER ASSISTANCE SYSTEM, english: ADAS) early warning information at a position of tens of meters, and further extended to a position of hundreds of meters, so as to realize virtual-real fusion with long-distance road elements such as lane lines. The augmented reality head-up display system does not actually project an image to a remote road surface, but enables a driver to perceive a virtual image to be displayed on a road in front through precise optical design, so that fusion with a real scene is realized. The physical light path of the optical projection assembly is controlled within a limited range despite the relatively large virtual image distance. In order to achieve the functions, an optical projection assembly of an augmented reality head-up display system has strict optical requirements, namely, the optical projection assembly is required to have a long focal length to achieve virtual image distances of tens of meters or hundreds of meters and meet the projection requirements of far-field augmented reality information, secondly, chromatic aberration can be effectively corrected under a visible light broadband, halos generated at the edges of a color image are avoided, display quality is ensured, thirdly, the optical projection assembly is required to have high resolution, low aberration and low distortion to ensure that projection elements such as navigation arrows and early warning marks are accurately attached to real lane lines, fourthly, image space telecentricity is required to be strictly controlled to match the coupling efficiency of optical waveguides, and meanwhile, miniaturized design is achieved to adapt to limited space layout of an instrument desk. The Chinese patent publication No. CN116736533A discloses a projection lens and a display system applied to a waveguide type augmented reality head-up display system, which realize higher resolution (MTF0.5@125Lp/mm) and low aberration (field curvature + -0.05 mm and distortion 0.2%), realize small volume (caliber 10mm and total length 15 mm), but do not consider the influence of chromatic aberration under a visible light broadband on the effect of a projection image, have shorter focal length (f=6-10 mm), and are only suitable for a projection scene with a shorter working distance. The Chinese patent publication No. CN119335687A discloses a projection lens and a head-up display system, five single lenses are used, ultrathin and miniaturized lenses (caliber is 16mm, total length is 30 mm) are realized, a longer focal length (34 mm) can be realized, an imaging range from 2m to infinity can be realized, meanwhile, chromatic aberration is controlled to be 0.3 pixel (0.0015 mm), imaging resolution is high (MTF0.6@66Lp/mm), aberration distortion of an optical system is 0.4%, so that overlapping degree of a projection image and a real road background is insufficient under different view angles on a long distance, and accuracy of projection path guiding can be reduced. Disclosure of Invention The invention aims to provide a long-focus optical projection assembly with high resolution, long focus and low aberration and low chromatic aberration. The technical scheme adopted for solving the technical problems is as follows: the long-focal-length optical projection assembly consists of a diaphragm and a plurality of lenses from an object side to an image side, wherein the plurality of lenses are a first lens with positive focal power, a second lens with negative focal power, a third lens with positive focal power, a fourth lens with positive focal power and a fifth lens with negative focal power, the object side of the first lens is an aspheric surface, the second lens is a biconcave lens, the third lens is a meniscus lens with a concave surface facing the object side, both side surfaces of the fourth lens and the fifth lens are aspheric surfaces, the image side curvature radius R3