A scanning lens with a simple structure

Abstract

The present invention provides a scanning lens with a simple structure, which successively includes five parts from the object surface to the image surface: a stop (STO), a first lens (L1), a second lens (L2), an infrared filter (IR), and a chip protection glass (CG); wherein the first lens (L1) is a positive lens, its object side is concave, and its image side is convex; the second lens (L2) is a negative lens, its object side is concave, and its image side is convex. A scanning lens with a simple structure provided by the present invention satisfies the following relationships: 0.52 < f1 / f < 0.77; -1.2 < f2 / f < -0.9; where f1 is the effective focal length of the first lens (L1), f2 is the effective focal length of the second lens (L2), and f is the effective focal length of the lens. The structure of the present invention is simple, only including two optical lenses, with low production cost, easy assembly, mass production feasibility, and high imaging quality.

Description

[Technical field]

[0001] The invention relates to a scanning lens with a simple structure. [Background technology]

[0002] In recent years, with the continuous increase in the amount of barcode information, more and more image scanning technologies have replaced the previous laser barcode scanning technology. In certain occasions, dedicated scanning equipment is often required to accurately and efficiently scan and identify information. The market has increasingly higher requirements for scanning lenses, including smaller size, higher imaging quality, and lower cost.

[0003] The present invention is made based on the above market demand. [Summary of the invention]

[0004] The present invention aims to provide a scanning lens with a simple structure, which has the advantages of simple structure, low cost, and easy production. At the same time, the lens has small distortion and high imaging quality.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A scanning lens with a simple structure, including five parts from the object plane to the image plane: aperture (STO), first lens (L1), second lens (L2), filter (IR), chip protection glass (CG); the first lens (L1) is a positive lens, its object side surface is concave, and the image side surface is convex; the second lens (L2) is a negative lens, its object side surface is concave, and the image side surface is convex.

[0007] The above-mentioned scanning lens with a simple structure satisfies the following relationship:

[0008] 0.52 <f1 / f<0.77;

[0009] -1.2 <f2 / f<-0.9;

[0010] Among them, f1 is the effective focal length of the first lens (L1), f2 is the effective focal length of the second lens (L2), and f is the effective focal length of the scanning lens with a simple structure.

[0011] The above-mentioned scanning lens with a simple structure satisfies the following relationship:

[0012] 10 <L / TTL<15;

[0013] Wherein, TTL is the distance from the object side of the first lens (L1) of the scanning lens with a simple structure to the image plane on the optical axis, and L is the optimal imaging object distance of the lens.

[0014] The above-mentioned scanning lens with a simple structure satisfies the following relationship:

[0015] 0.1 <D / f<0.5;

[0016] ILL>80%;

[0017] Wherein, D is the effective diameter of the scanning lens aperture (STO) of the present simple structure, f is the effective focal length of the lens, and ILL is the relative illumination of the lens.

[0018] The above-mentioned scanning lens with a simple structure satisfies the following relationship:

[0019] 0.72 <T1 / ∑T<0.93;

[0020] 0.1 <T2 / ∑T<0.33;

[0021] Wherein, T1 and T2 are respectively the thickness of the first lens (L1) and the second lens (L2) of the simple scanning lens on the optical axis, and ∑T is the total thickness of the first lens (L1) and the second lens (L2) of the lens on the optical axis.

[0022] The above-mentioned scanning lens with a simple structure satisfies the following relationship:

[0023] 30 <Vd1-Vd2<36;

[0024] Wherein, Vd1 and Vd2 are the Abbe numbers of the first lens (L1) and the second lens (L2) of the simple scanning lens of the present invention.

[0025] The above-mentioned scanning lens with a simple structure satisfies the following relationship:

[0026] 0.82 <f*tan(ω / 2) / ImgH<1.2;

[0027] Wherein, f is the effective focal length of the scanning lens with a simple structure, ω is the field angle of the lens, and ImgH is the maximum half image height of the lens.

Brief Description of the Drawings

[0028] Figure 1 This is a schematic diagram of the optical system structure of a scanning lens with a simple structure;

[0029] Figure 2 This is a distortion diagram of the optical system of a scanning lens with a simple structure;

[0030] Figure 3 This is the astigmatism curve of the optical system of a scanning lens with a simple structure. [Specific implementation method]

[0031] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the figures. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0032] like Figure 1 As shown, a scanning lens with a simple structure proposed by the present invention comprises five parts from the object plane to the image plane: an aperture (STO), a first lens (L1), a second lens (L2), a filter (IR), and a chip protection glass (CG); wherein the first lens (L1) is a positive lens, whose object side surface is a concave surface and whose image side surface is a convex surface; and the second lens (L2) is a negative lens, whose object side surface is a concave surface and whose image side surface is a convex surface.

[0033] The above-mentioned scanning lens with a simple structure satisfies the following relationship:

[0034] 0.52 <f1 / f<0.77;(1)

[0035] -1.2 <f2 / f<-0.9;(2)

[0036] Wherein, f1 is the effective focal length of the first lens (L1), f2 is the effective focal length of the second lens (L2), and f is the effective focal length of the scanning lens with a simple structure. A scanning lens with a simple structure, which contains only two optical lenses and uses a combination of positive and negative lenses, can effectively shorten the length of the lens and make the lens structure compact when equations (1) and (2) are met, and is also conducive to correcting astigmatism and controlling distortion.

[0037] The above-mentioned scanning lens with a simple structure satisfies the following relationship:

[0038] 10 <L / TTL<15;(3)

[0039] Wherein, TTL is the distance from the object side of the first lens (L1) of the scanning lens with a simple structure to the image plane on the optical axis, and L is the optimal imaging object distance of the lens. The above formula (3) can balance the long-range and short-range resolutions of the lens optical system. When the ratio of the optimal object distance to the total length of the lens is lower than the lower limit, the long-range resolution deteriorates, and when the ratio is higher than the upper limit, the short-range resolution deteriorates.

[0040] The above-mentioned scanning lens with a simple structure satisfies the following relationship:

[0041] 0.1 <D / f<0.5;(4)

[0042] ILL>80%; (5)

[0043] Where D is the effective diameter of the simple scanning lens aperture (STO), f is the effective focal length of the lens, and ILL is the relative illumination of the lens. The lens aperture is a rectangular aperture with a small aperture diameter, which is conducive to controlling stray light and aberrations. When satisfying equations (4) and (5), the incident light flux is increased and the image brightness is improved.

[0044] The above-mentioned scanning lens with a simple structure satisfies the following relationship:

[0045] 0.72 <T1 / ∑T<0.93;(6)

[0046] 0.1 <T2 / ∑T<0.33;(7)

[0047] Wherein, T1 and T2 are respectively the thickness of the first lens (L1) and the second lens (L2) of the simple scanning lens on the optical axis, and ∑T is the total thickness of the first lens (L1) and the second lens (L2) of the lens on the optical axis.

[0048] The present invention contains only two optical lenses. When equations (6) and (7) are satisfied, the thickness of the first lens (L1) and the second lens (L2) are moderate, thereby reducing the tolerance sensitivity of the lens optical system and shortening the overall length.

[0049] The above-mentioned scanning lens with a simple structure satisfies the following relationship:

[0050] 30 <Vd1-Vd2<36;(8)

[0051] Wherein, Vd1 and Vd2 are the Abbe numbers of the first lens (L1) and the second lens (L2) of the simple scanning lens of the present invention. When the lens satisfies the above formula (8), it is helpful to correct chromatic aberration and image aberration, and effectively avoids the situation of large magnification chromatic aberration and image color distortion.

[0052] The above-mentioned scanning lens with a simple structure satisfies the following relationship:

[0053] 0.82 <f*tan(ω / 2) / ImgH<1.2;(9)

[0054] Wherein, f is the effective focal length of the scanning lens with a simple structure, ω is the field angle of the lens, and ImgH is the maximum half image height of the lens. The above formula (9) can be used to constrain the field size of the lens optical system to avoid the field angle being too large or too small, resulting in the object height not meeting the requirements and the optical system distortion being too serious.

[0055] In summary, the scanning lens with a simple structure provided by the present invention has the following advantages compared with the prior art:

[0056] The invention has a simple structure, low cost and mass production capability. Meanwhile, the lens design uses a rectangular aperture, which effectively restrains stray light and aberration of the lens optical system, so that the lens has higher imaging quality.

[0057] The following table is a lens data table of a specific embodiment.

[0058] Table 1 is a structural parameter table of a simple scanning lens

[0059] Surface Type Radius(mm) Thickness(mm) Glass Object Sphere Infinity 99 Stop Sphere Infinity 0.02 2 Asphere 168.178 2.365 1.54:56.2 3 Asphere -2.224 2.456 4 Asphere -3.881 0.430 1.63:23.4 5 Asphere 216.536 0.02 6 Sphere Infinity 0.21 1.52:61.2 7 Sphere Infinity 1.68 8 Sphere Infinity 0.3 1.52:61.2 9 Sphere Infinity 0.13 Image Sphere Infinity 0

[0060] Table 2 shows the ratio of the sag height to the radius R of the first lens (L1) of a simple scanning lens.

[0061]

[0062]

[0063] Table 3 shows the ratio of the sag height to the radius R of the second lens (L2) of a simple scanning lens.

[0064]

Claims

1. A scanning lens with a simple structure, characterized by The scanning lens includes five parts from the object plane to the image plane: an aperture (STO), a first lens (L1), a second lens (L2), a filter (IR), and a chip protection glass (CG); wherein the first lens (L1) is a positive lens, whose object side surface is concave and whose image side surface is convex; the second lens (L2) is a negative lens, whose object side surface is concave and whose image side surface is convex, and the scanning lens with a simple structure satisfies the following relationship: 0.52 <f1 / f<0.77; -1.2 <f2 / f<-0.9; 10 <L / TTL<15; 0.1 <D / f<0.5; ILL>80%; 0.72 <T1 / ∑T<0.93; 0.1 <T2 / ∑T<0.33; 30 <Vd1-Vd2<36; 0.82 <f*tan(ω / 2) / ImgH<1.2; Wherein, f is the effective focal length of the scanning lens with a simple structure, f1 is the effective focal length of the first lens (L1) of the lens, and f2 is the effective focal length of the second lens (L2) of the lens; TTL is the distance from the object side of the first lens (L1) of the lens to the image plane on the optical axis, and L is the optimal imaging object distance of the lens; D is the effective diameter of the lens aperture (STO), and ILL is the relative illumination of the lens; T1 and T2 are the thicknesses of the first lens (L1) and the second lens (L2) of the lens on the optical axis, respectively, and ∑T is the sum of the thicknesses of the first lens (L1) and the second lens (L2) of the lens on the optical axis; Vd1 and Vd2 are the Abbe numbers of the first lens (L1) and the second lens (L2) of the lens, respectively; ω is the field of view of the lens, and ImgH is the maximum half image height of the lens.

Images