A low-distortion scanning lens

Abstract

This patent discloses a low-distortion scanning lens, belonging to the field of optical lenses. It includes a first lens element (L1), a second lens element (L2), a third lens element (L3), an aperture stop (STO), a fourth lens element (L4), a fifth lens element (L5), a sixth lens element (L6), and a seventh lens element (L7) arranged sequentially from the object plane to the image plane. The first lens element (L1), the second lens element (L2), the fifth lens element (L5), and the seventh lens element (L7) are negative lenses, while the third lens element (L3), the fourth lens element (L4), and the sixth lens element (L6) are positive lenses. This lens has high resolution, low distortion, high relative illumination, short total length, low tolerance sensitivity, and is suitable for mass production.

Description

Technical Field

[0001] This patent belongs to the field of optical lens technology, and more specifically, relates to consumer electronics lenses. Background Technology

[0002] With the continuous development of technology, scanning lenses are widely used in laser processing, 3D printing, barcode scanning, LiDAR, medical imaging, and other fields. However, they also face problems such as large optical distortion and high manufacturing and assembly precision, which affect scanning accuracy. Against this background, this patent proposes a low-distortion scanning lens to meet the needs of high-performance scanning technology. Summary of the Invention

[0003] To meet current market demands, this patent provides a low-distortion scanning lens, with the aim of obtaining a lens with high resolution, low distortion, and low tolerance sensitivity.

[0004] To achieve the above objectives, this patent provides a low-distortion scanning lens, which consists of seven lenses, including a first lens element (L1), a second lens element (L2), a third lens element (L3), an aperture stop (STO), a fourth lens element (L4), a fifth lens element (L5), a sixth lens element (L6), a seventh lens element (L7), an IR filter, and a chip protective glass (CG), arranged sequentially from the object plane to the image plane. The first lens element (L1) is a plastic aspherical negative lens with a convex object-side surface and a concave image-side surface. The second lens element (L2) is also a plastic aspherical negative lens with a convex object-side surface and a concave image-side surface. The first lens element (L3) is a plastic aspherical positive lens with a convex object-side surface and a convex image-side surface; the second lens element (L4) is a plastic aspherical positive lens with a convex object-side surface and a convex image-side surface; the third lens element (L3) is a plastic aspherical negative lens with a concave object-side surface and a concave image-side surface; the fourth lens element (L4) is a plastic aspherical positive lens with a convex object-side surface and a convex image-side surface; the fifth lens element (L5) is a plastic aspherical negative lens with a concave object-side surface and a concave image-side surface; the sixth lens element (L6) is a plastic aspherical positive lens with a convex object-side surface and a convex image-side surface; the seventh lens element (L7) is a plastic aspherical negative lens with a convex object-side surface and a concave image-side surface; and the focal length of each lens element satisfies the following relationship: -2.265 <f1 / f<-1.942;-2.156<f2 / f<-1.903;1.421<f3 / f<1.781;1.820<f4 / f<2.197;-1.658<f5 / f<-1.408;1.481<f6 / f<1.826;-8.9174<f7 / f<-8.230;

[0005] Wherein, f1 is the effective focal length of the first lens element (L1), f2 is the effective focal length of the second lens element (L2), f3 is the effective focal length of the third lens element (L3), f4 is the effective focal length of the fourth lens element (L4), f5 is the effective focal length of the fifth lens element (L5), f6 is the effective focal length of the sixth lens element (L6), f7 is the effective focal length of the seventh lens element (L7), and f is the effective focal length of a low-distortion scanning lens.

[0006] Preferably, the following relationship is satisfied: f / F < 0.16; where F is the aperture number of a low-distortion scanning lens.

[0007] Preferably, the following relationship is also satisfied: ;in This represents the average luminous flux in the image plane edge region. This represents the average luminous flux in the central region of the image plane.

[0008] Preferably, the following relationship is also satisfied: ∑TC / ∑TE<1.15; where ∑TC is the sum of the lens thicknesses of the first lens element (L1), the second lens element (L2), the third lens element (L3), the fourth lens element (L4), the fifth lens element (L5), the sixth lens element (L6), and the seventh lens element (L7) on the optical axis, and ∑TE is the sum of the axial thicknesses of the first lens element (L1), the second lens element (L2), the third lens element (L3), the fourth lens element (L4), the fifth lens element (L5), the sixth lens element (L6), and the seventh lens element (L7) at their maximum aperture.

[0009] Preferably, the following relationship is also satisfied: 0.05 <T1 / ∑TC<0.08;0.05<T2 / ∑TC<0.07;0.19<T3 / ∑TC<0.21;0.14<T4 / ∑TC<0.16;0.05<T5 / ∑TC<0.07;0.27<T6 / ∑TC<0.29;0.18<T7 / ∑TC<0.20;

[0010] Where T1, T2, T3, T4, T5, T6, and T7 are the lens thicknesses on the optical axis of the first lens element (L1), the second lens element (L2), the third lens element (L3), the fourth lens element (L4), the fifth lens element (L5), the sixth lens element (L6), and the seventh lens element (L7), respectively.

[0011] Overall, the technical solutions conceived in this patent have the following advantages compared with existing technologies:

[0012] (1) The total length of the lens disclosed in this patent is short, which is conducive to miniaturization; (2) The lens of this patent has small distortion, which is conducive to improving scanning accuracy; (3) The lens of this patent has high relative illumination, which meets the requirements of scanning lens use; (4) The lens of this patent, through the combination of positive and negative lenses and reasonable lens thickness, is conducive to reducing tolerance sensitivity and mass production. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the structure of the first embodiment of this patent;

[0014] Figure 2 This is a distortion diagram of the first embodiment of this patent;

[0015] Figure 3 This is the MTF diagram of the first embodiment of this patent;

[0016] Figure 4 This is a schematic diagram of the structure of the second embodiment of this patent;

[0017] Figure 5 This is a distortion diagram of the second embodiment of this patent;

[0018] Figure 6 This is the MTF diagram of the second embodiment of this patent. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this patent clearer, the following detailed description, in conjunction with the accompanying drawings and embodiments, further clarifies the patent. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of the patent. Furthermore, the technical features involved in the various embodiments of this patent described below can be combined with each other as long as they do not conflict with each other.

[0020] 1. A low-distortion scanning lens, characterized in that it comprises, in sequence from the object plane to the image plane, a first lens element (L1), a second lens element (L2), a third lens element (L3), an aperture stop (STO), a fourth lens element (L4), a fifth lens element (L5), a sixth lens element (L6), a seventh lens element (L7), an IR filter, and a chip protective glass (CG); the first lens element (L1) is a plastic aspherical negative lens, with its object-side surface being convex and its image-side surface being concave; the second lens element (L2) is a plastic aspherical negative lens, with its object-side surface being convex and its image-side surface being concave; The object side is concave, and the image side is concave; the third lens element (L3) is a plastic aspherical positive lens with a convex object side and a convex image side; the fourth lens element (L4) is a plastic aspherical positive lens with a convex object side and a convex image side; the fifth lens element (L5) is a plastic aspherical negative lens with a concave object side and a concave image side; the sixth lens element (L6) is a plastic aspherical positive lens with a convex object side and a convex image side; the seventh lens element (L7) is a plastic aspherical negative lens with a convex object side and a concave image side.

[0021] Furthermore, the focal lengths of each lens element satisfy the following relationship:

[0022] -2.265 <f1 / f<-1.942;

[0023] -2.156 <f2 / f<-1.903;

[0024] 1.421 <f3 / f<1.781;

[0025] 1.820 <f4 / f<2.197;

[0026] -1.658 <f5 / f<-1.408;

[0027] 1.481 <f6 / f<1.826;

[0028] -8.9174 <f7 / f<-8.230;

[0029] Wherein, f1 is the effective focal length of the first lens element (L1), f2 is the effective focal length of the second lens element (L2), f3 is the effective focal length of the third lens element (L3), f4 is the effective focal length of the fourth lens element (L4), f5 is the effective focal length of the fifth lens element (L5), f6 is the effective focal length of the sixth lens element (L6), f7 is the effective focal length of the seventh lens element (L7), and f is the effective focal length of a low-distortion scanning lens.

[0030] The optical system adopts a negative-negative-positive-negative-positive-negative structure, and the focal length of each lens is relatively close to the focal length ratio of the optical system. This is beneficial for balancing the optical power of each lens, making the light-reflecting ability of each lens comparable, and reducing the sensitivity of each lens to tolerance.

[0031] 2. The low-distortion scanning lens described above satisfies the following relationship:

[0032] f / F < 0.8;

[0033] Where F represents the aperture number of a low-distortion scanning lens.

[0034] 3. The low-distortion scanning lens described above satisfies the following relationship: ;in This represents the average luminous flux in the image plane edge region. This refers to the average luminous flux in the central region of the image plane. This patent optimizes the lens curvature to ensure that the luminous flux at the edge is no less than 60% of the luminous flux at the center.

[0035] 4. The aforementioned low-distortion scanning lens also satisfies the following relationship:

[0036] ∑TC / ∑TE<1.15;

[0037] Where ∑TC is the sum of the lens thicknesses of the first lens element (L1), the second lens element (L2), the third lens element (L3), the fourth lens element (L4), the fifth lens element (L5), the sixth lens element (L6), and the seventh lens element (L7) along the optical axis, and ∑TE is the sum of the axial thicknesses of the first lens element (L1), the second lens element (L2), the third lens element (L3), the fourth lens element (L4), the fifth lens element (L5), the sixth lens element (L6), and the seventh lens element (L7) at their maximum aperture.

[0038] The ratio of the sum of the center thickness to the sum of the edge thicknesses of all lenses is close to 1, indicating that the optical path traveled by the light rays in the central field of view and the edge field of view is similar, and no obvious curved image will be formed when they reach the image plane, which helps to reduce distortion.

[0039] 5. The low-distortion scanning lens has a field of view of over 110°, and a sufficiently large field of view is also beneficial for the scanning lens to acquire more information.

[0040] 6. The aforementioned low-distortion scanning lens also satisfies the following relationship:

[0041] 0.05 <T1 / ∑TC<0.08;

[0042] 0.05 <T2 / ∑TC<0.07;

[0043] 0.19 <T3 / ∑TC<0.21;

[0044] 0.14 <T4 / ∑TC<0.16;

[0045] 0.05 <T5 / ∑TC<0.07;

[0046] 0.27 <T6 / ∑TC<0.29;

[0047] 0.18 <T7 / ∑TC<0.20;

[0048] Where T1, T2, T3, T4, T5, T6, and T7 are the lens thicknesses on the optical axis of the first lens element (L1), the second lens element (L2), the third lens element (L3), the fourth lens element (L4), the fifth lens element (L5), the sixth lens element (L6), and the seventh lens element (L7), respectively.

[0049] The center thicknesses of each lens are relatively close and the distribution is reasonable, which helps to reduce aberrations while also reducing the tolerance sensitivity of the lenses.

[0050] Example 1

[0051] As a specific embodiment of this patent, the parameters of a low-distortion scanning lens are shown in Tables 1 and 2 below:

[0052] Table 1. Structural parameters of a low-distortion scanning lens

[0053]

[0054] Table 2. Surface coefficient of an aspherical lens for a low-distortion scanning lens.

[0055]

[0056]

[0057]

[0058]

[0059] Example 2

[0060] As a specific embodiment of this patent, the parameters of a low-distortion scanning lens are shown in Tables 3 and 4 below:

[0061] Table 3. Structural parameters of a low-distortion scanning lens

[0062]

[0063] Table 4. Surface coefficient of an aspherical lens for a low-distortion scanning lens.

[0064]

[0065]

[0066]

[0067]

[0068] Those skilled in the art will readily understand that the above are merely preferred embodiments of this patent and are not intended to limit this patent. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this patent should be included within the scope of protection of this patent.

Claims

1. A low-distortion scanning lens, characterized in that, This lens consists of seven lenses, including a first lens element (L1), a second lens element (L2), a third lens element (L3), an aperture stop (STO), a fourth lens element (L4), a fifth lens element (L5), a sixth lens element (L6), a seventh lens element (L7), an IR filter, and a chip protection glass (CG), arranged sequentially from the object plane to the image plane. The first lens element (L1) is a plastic aspherical negative lens with a convex object-side surface and a concave image-side surface. The second lens element (L2) is also a plastic aspherical negative lens with a concave object-side surface. The object-side surface of the first lens element is concave; the third lens element (L3) is a plastic aspherical positive lens with a convex object-side surface and a convex image-side surface; the fourth lens element (L4) is a plastic aspherical positive lens with a convex object-side surface and a convex image-side surface; the fifth lens element (L5) is a plastic aspherical negative lens with a concave object-side surface and a concave image-side surface; the sixth lens element (L6) is a plastic aspherical positive lens with a convex object-side surface and a convex image-side surface; and the seventh lens element (L7) is a plastic aspherical negative lens with a convex object-side surface and a concave image-side surface. Furthermore, the focal lengths of each lens element satisfy the following relationship: -2.265 <f1 / f<-1.942; -2.156 <f2 / f<-1.903; 1.421 <f3 / f<1.781; 1.820 <f4 / f<2.197; -1.658 <f5 / f<-1.408; 1.481 <f6 / f<1.826; -8.9174 <f7 / f<-8.230; Wherein, f1 is the effective focal length of the first lens element (L1), f2 is the effective focal length of the second lens element (L2), f3 is the effective focal length of the third lens element (L3), f4 is the effective focal length of the fourth lens element (L4), f5 is the effective focal length of the fifth lens element (L5), f6 is the effective focal length of the sixth lens element (L6), f7 is the effective focal length of the seventh lens element (L7), and f is the effective focal length of a low-distortion scanning lens.

2. The low-distortion scanning lens as described in claim 1, characterized in that, The following relationship must be satisfied: f / F < 0.8; Where F represents the aperture number of a low-distortion scanning lens.

3. The low-distortion scanning lens as described in claim 1, characterized in that, The following relationship must be satisfied: ； in This represents the average luminous flux in the image plane edge region. This represents the average luminous flux in the central region of the image plane.

4. The low-distortion scanning lens as described in claim 1, characterized in that, It also satisfies the following relation: ∑TC / ∑TE<1.15; Where ∑TC is the sum of the lens thicknesses of the first lens element (L1), the second lens element (L2), the third lens element (L3), the fourth lens element (L4), the fifth lens element (L5), the sixth lens element (L6), and the seventh lens element (L7) along the optical axis, and ∑TE is the sum of the axial thicknesses of the first lens element (L1), the second lens element (L2), the third lens element (L3), the fourth lens element (L4), the fifth lens element (L5), the sixth lens element (L6), and the seventh lens element (L7) at their maximum aperture.

5. A low-distortion scanning lens as described in claim 1, characterized in that... It also satisfies the following relation: 0.05 <T1 / ∑TC<0.08; 0.05 <T2 / ∑TC<0.07; 0.19 <T3 / ∑TC<0.21; 0.14 <T4 / ∑TC<0.16; 0.05 <T5 / ∑TC<0.07; 0.27 <T6 / ∑TC<0.29; 0.18 <T7 / ∑TC<0.20; Where T1, T2, T3, T4, T5, T6, and T7 are the lens thicknesses on the optical axis of the first lens element (L1), the second lens element (L2), the third lens element (L3), the fourth lens element (L4), the fifth lens element (L5), the sixth lens element (L6), and the seventh lens element (L7), respectively.

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