Bar code recognition lens

Abstract

The utility model discloses a bar code recognition lens. A first lens (L1), a second lens (L2), a diaphragm (STO), a third lens (L3), a fourth lens (L4), a fifth lens (L5) and an optical filter (L6) are sequentially arranged from an object plane to an image plane; the first lens (L1) is a negative lens, the object side surface is a convex surface, the image side surface is a concave surface, the second lens (L2) is a positive lens, the object side surface is a convex surface, the image side surface is a concave surface, the third lens (L3) is a positive lens, the object side surface is a convex surface, the image side surface is a convex surface, the fourth lens (L4) is a negative lens, the object side surface is a concave surface, the image side surface is a concave surface, and the fifth lens (L5) is a positive lens, the object side surface is a convex surface. The image side surface is a convex surface; the first lens to the fifth lens are made of plastic materials, so that the cost can be greatly reduced; the combination of the positive lens and the negative lens facilitates correction of field curvature and distortion and also facilitates reduction of the total length of the optical system.

Description

Technical Field

[0001] The present invention relates to a barcode recognition lens, which is particularly applicable to the field of industrial barcode recognition, and can quickly and accurately recognize barcode information, improving work efficiency and accuracy.

Background Art

[0002] In modern industrial production, barcode recognition technology is widely used in logistics, warehousing, production management and other links. Traditional barcode recognition lenses have various problems, such as low imaging quality, limited field of view angle, poor adaptability to different environments, etc. These problems limit the application scope and efficiency of barcode recognition systems. Therefore, developing a high-performance barcode recognition lens has important practical significance.

Summary of the Invention

[0003] In view of the above problems, the present invention proposes a barcode recognition lens based on a plastic aspherical lens, which realizes the technical effects of high resolution, low distortion and low cost by optimizing the lens focal power distribution, aspherical design and compact layout.

[0004] The technical solution adopted by the present invention is as follows:

[0005] A barcode recognition lens, characterized in that: along the optical axis from the object side to the imaging surface, a first lens (L1), a second lens (L2), an aperture stop (STO), a third lens (L3), a fourth lens (L4), a fifth lens (L5), and a filter (G6) are sequentially provided; the first lens (L1) is a negative lens, made of plastic material, and its focal length satisfies -3.0 < f1 / f < -1.5; the object side is a convex surface and is an aspherical surface, and the image side is a concave surface and is an aspherical surface;

[0006] The second lens (L2) is a positive lens, made of plastic material, and its focal length satisfies 7.5 < f2 / f < 9.0; the object side is a convex surface and is an aspherical surface, and the image side is a concave surface and is an aspherical surface;

[0007] The third lens (L3) is a positive lens, made of plastic material, and its focal length satisfies 1.7 < f3 / f < 2.0; the object side is a convex surface and is an aspherical surface, and the image side is a convex surface and is an aspherical surface;

[0008] The fourth lens (L4) is a negative lens, made of plastic material, and its focal length satisfies -2.9 < f4 / f < -2.0; the object side is a concave surface and is an aspherical surface, and the image side is a concave surface and is an aspherical surface;

[0009] The fifth lens (L5) is a positive lens, made of plastic material, and its focal length satisfies 1.3 < f5 / f < 1.9; the object side is a convex surface and is an aspherical surface, and the image side is a convex surface and is a spherical surface;

[0010] The barcode recognition camera satisfies the following relationship: 8.2 <TTL / f<9.1;

[0011] Where f1 is the effective focal length of the first lens, f2 is the effective focal length of the second lens, f3 is the effective focal length of the third lens, f4 is the effective focal length of the fourth lens, f5 is the effective focal length of the fifth lens, TTL is the on-axis distance from the object side of the first lens to the imaging plane, and f is the effective focal length of the barcode recognition lens.

[0012] Further preferably, the barcode recognition lens is characterized in that it satisfies the following relationship:

[0013] 1.1 <T12 / f<1.7;

[0014] 0.71 <T23 / f<0.82;

[0015] 0.02 <T34 / f<0.11;

[0016] 0.09 <T45 / f<0.17;

[0017] Wherein, T12 is the air gap between the first and second lenses on the optical axis, T23 is the air gap between the second and third lenses on the optical axis, T34 is the air gap between the third and fourth lenses on the optical axis, and T45 is the air gap between the fourth and fifth lenses on the optical axis.

[0018] Further preferably, the barcode recognition lens is characterized in that the aperture stop is located between the object-side surface of the second lens and the third lens, and satisfies the following relationship:

[0019] 0.1 <TDS / f34<0.5;

[0020] Where TDS is the aperture stop diameter, and f34 is the focal length of the lens group consisting of the third and fourth lenses.

[0021] Further preferably, the barcode recognition lens is characterized in that it satisfies the following relationship:

[0022] TTL < 15;

[0023] 105° <FOV<120°;

[0024] TTL is the distance on the optical axis from the object side surface of the first lens to the image plane, and FOV is the maximum field of view of this barcode recognition lens.

[0025] Further preferably, the barcode recognition lens is characterized in that it satisfies the following relationship:

[0026] -1.20 <T3-T1<-0.80;

[0027] -2.50 <T4-T2<-1.97;

[0028] -0.81 <T5-T3<-0.42;

[0029] Wherein, T1 is the distance on the optical axis from the object side surface of the first lens to the image side surface of the first lens, T2 is the distance on the optical axis from the object side surface of the second lens to the image side surface of the second lens, T3 is the distance on the optical axis from the object side surface of the third lens to the image side surface of the third lens, T4 is the distance on the optical axis from the object side surface of the fourth lens to the image side surface of the fourth lens, and T5 is the distance on the optical axis from the object side surface of the fifth lens to the image side surface of the fifth lens.

[0030] Further preferably, the barcode recognition lens is characterized in that it satisfies the following relationship:

[0031] 0.9 <T3-SA6<1.1;

[0032] Where T3 is the distance on the optical axis from the object side surface of the third lens to the image side surface of the third lens, and SA6 is the distance on the optical axis from the center of the aspherical surface of the image side surface of the third lens to the maximum effective diameter.

[0033] Further preferably, the barcode recognition lens is characterized in that it satisfies the following relationship:

[0034] 0.28 <T1 / ∑T<0.35;

[0035] 0.29 <T2 / ∑T<0.34;

[0036] 0.17 <T3 / ∑T<0.23;

[0037] 0.03 <T4 / ∑T<0.08;

[0038] 0.09 <T5 / ∑T<0.15;

[0039] Where ∑T is the sum of the lens thicknesses of the first lens, second lens, third lens, fourth lens, and fifth lens on the optical axis, and T1, T2, T3, T4, and T5 are the lens thicknesses of the first lens, second lens, third lens, and fourth lens on the optical axis, respectively.

[0040] The barcode recognition lens of this invention achieves high resolution, a wide field of view, and a compact structure through optimized lens group design. Compared with the prior art, this invention has the following advantages:

[0041] High image quality: By precisely controlling the focal length and shape of each lens, the sharpness and accuracy of the image are improved.

[0042] Large field of view: It meets the design requirement of 105° < FOV < 120°, can cover a wider barcode area, and improve the recognition efficiency.

[0043] Compact structure: On the premise of meeting the imaging requirements, a compact structure design is achieved, which is convenient for integration into various devices.

[0044] Strong adaptability: It can adapt to different working environments and has good stability and reliability.

BRIEF DESCRIPTION OF THE DRAWINGS

[0045] The above and / or additional aspects and advantages of the present invention will become obvious and easy to understand from the description of the embodiments in conjunction with the following drawings, where:

[0046] Figure 1 is a schematic structural diagram of the barcode recognition lens.

[0047] Figure 2 is the field curvature diagram (%) of the barcode recognition lens.

[0048] Figure 3 is the distortion diagram (%) of the barcode recognition lens.

[0049] Figure 4 is the lateral chromatic aberration diagram (mm) of the barcode recognition lens.

DETAILED DESCRIPTION

[0050] To better understand the present application, more detailed descriptions of various aspects of the present application will be made with reference to the drawings. It should be understood that these detailed descriptions are only descriptions of the embodiments of the present application and do not limit the scope of the present application in any way. Throughout the specification, the same reference numerals refer to the same elements. The expression "and / or" includes any and all combinations of one or more of the associated listed items.

[0051] It should be noted that in this specification, the expressions such as first, second, third, etc. are only used to distinguish one feature from another feature and do not represent any limitation on the features. Therefore, without departing from the teachings of the present invention, the first lens discussed below may also be referred to as the second lens or the third lens.

[0052] In the drawings, for the sake of convenience of illustration, the thickness, size, and shape of the lens have been slightly exaggerated. Specifically, the spherical or aspherical shapes shown in the drawings are shown by way of example. That is, the spherical or aspherical shapes are not limited to the spherical or aspherical shapes shown in the drawings; the drawings are only examples and are not drawn strictly to scale.

[0053] In this text, the paraxial region refers to the region near the optical axis. If the lens surface is convex and the position of the convex surface is not defined, it means that the lens surface is convex at least in the paraxial region; if the lens surface is concave and the position of the concave surface is not defined, it means that the lens surface is concave at least in the paraxial region. The surface of each lens closest to the object to be photographed is called the object side surface of the lens, and the surface of each lens closest to the imaging surface is called the image side surface of the lens.

[0054] It should also be understood that the terms "comprising", "comprising of", "having", "containing" and / or "containing of", when used in this specification, indicate the presence of the stated features, elements and / or components, but do not exclude the presence or addition of one or more other features, elements, components and / or combinations thereof. In addition, when an expression such as "at least one of..." appears after a list of listed features, it modifies the entire list of listed features, rather than an individual element in the list. In addition, when describing the embodiments of the present application, the use of "may" means "one or more embodiments of the present application". And, the term "exemplary" is intended to refer to an example or illustration.

[0055] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It should also be understood that terms (such as those defined in a common dictionary) should be interpreted as having a meaning consistent with their meaning in the context of the relevant art, and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0056] The following provides a detailed description of the specific embodiments of the present invention.

[0057] As Figure 1 shown, the present invention provides a bar code recognition lens, which is characterized in that: along the optical axis from the object side surface to the imaging surface, a first lens (L1), a second lens (L2), an aperture (STO), a third lens (L3), a fourth lens (L4), a fifth lens (L5), and a filter (G6) are sequentially provided;

[0058] The first lens (L1) is a negative lens, the material is a plastic material, and the focal length satisfies -3.0 < f1 / f < -1.5; the object side surface is convex and is an aspherical surface, and the image side surface is concave and is an aspherical surface;

[0059] The second lens (L2) is a positive lens, the material is a plastic material, and the focal length satisfies 7.5 < f2 / f < 9.0; the object side surface is convex and is an aspherical surface, and the image side surface is concave and is an aspherical surface;

[0060] The third lens (L3) is a positive lens made of plastic, and its focal length satisfies 1.7 < f3 / f < 2.0; the object side is convex and aspherical, and the image side is convex and aspherical;

[0061] The fourth lens (L4) is a negative lens made of plastic, and its focal length satisfies -2.9 < f4 / f < -2.0; the object side is concave and aspherical, and the image side is concave and aspherical;

[0062] The fifth lens (L5) is a positive lens made of plastic, and its focal length satisfies 1.3 < f5 / f < 1.9; the object side is convex and aspherical, and the image side is convex and spherical;

[0063] This barcode recognition lens satisfies the following relationship: 8.2 < TTL / f < 9.1;

[0064] Where, f1 is the effective focal length of the first lens, f2 is the effective focal length of the second lens, f3 is the effective focal length of the third lens, f4 is the effective focal length of the fourth lens, f5 is the effective focal length of the fifth lens, and TTL is the axial distance from the object side of the first lens to the imaging surface; f is the effective focal length of the barcode recognition lens.

[0065] By designing the focal length of the first lens within the range of -3.0 < f1 / f < -1.5, the total focal length of the lens can be effectively controlled, and at the same time, the imaging clarity, field curvature, and distortion can be optimized. Designing the focal length of the second lens within the range of 7.5 < f2 / f < 9.0 helps to improve the imaging brightness and contrast while reducing chromatic aberration; in addition, the first lens to the fifth lens are all made of plastic, which can greatly reduce the cost.

[0066] Further preferably, the barcode recognition lens is characterized in that it satisfies the following relationships:

[0067] 1.1 < T12 / f < 1.7;

[0068] 0.71 < T23 / f < 0.82;

[0069] 0.02 < T34 / f < 0.11;

[0070] 0.09 < T45 / f < 0.17;

[0071] Where, T12 is the air spacing between the first lens and the second lens on the optical axis, T23 is the air spacing between the second lens and the third lens on the optical axis, T34 is the air spacing between the third lens and the fourth lens on the optical axis, and T45 is the air spacing between the fourth lens and the fifth lens on the optical axis.

[0072] Further preferably, the barcode recognition lens is characterized in that the aperture stop is located between the object-side surface of the second lens and the third lens, and satisfies the following relationship:

[0073] 0.1 <TDS / f34<0.5;

[0074] Where TDS is the aperture stop diameter, and f34 is the focal length of the lens group consisting of the third and fourth lenses.

[0075] Further preferably, the barcode recognition lens is characterized in that it satisfies the following relationship:

[0076] TTL < 15;

[0077] 105° <FOV<120°;

[0078] TTL is the distance on the optical axis from the object side surface of the first lens to the image plane, and FOV is the maximum field of view of this barcode recognition lens.

[0079] Further preferably, the barcode recognition lens is characterized in that it satisfies the following relationship:

[0080] -1.20 <T3-T1<-0.80;

[0081] -2.50 <T4-T2<-1.97;

[0082] -0.81 <T5-T3<-0.42;

[0083] Wherein, T1 is the distance on the optical axis from the object-side surface of the first lens to the image-side surface of the first lens, T2 is the distance on the optical axis from the object-side surface of the second lens to the image-side surface of the second lens, T3 is the distance on the optical axis from the object-side surface of the third lens to the image-side surface of the third lens, T4 is the distance on the optical axis from the object-side surface of the fourth lens to the image-side surface of the fourth lens, and T5 is the distance on the optical axis from the object-side surface of the fifth lens to the image-side surface of the fifth lens. These relationships help to optimize image quality and reduce aberrations.

[0084] Further preferably, the barcode recognition lens is characterized in that it satisfies the following relationship:

[0085] 0.9 <T3-SA6<1.1;

[0086] Where T3 is the distance on the optical axis from the object side surface of the third lens to the image side surface of the third lens, and SA6 is the distance on the optical axis from the center of the aspherical surface of the image side surface of the third lens to the maximum effective diameter.

[0087] Further preferably, the barcode recognition lens is characterized in that it satisfies the following relationship:

[0088] 0.28 <T1 / ∑T<0.35;

[0089] 0.29 <T2 / ∑T<0.34;

[0090] 0.17 <T3 / ∑T<0.23;

[0091] 0.03 <T4 / ∑T<0.08;

[0092] 0.09 <T5 / ∑T<0.15;

[0093] Where ∑T is the sum of the lens thicknesses of the first lens, second lens, third lens, fourth lens, and fifth lens on the optical axis, and T1, T2, T3, T4, and T5 are the lens thicknesses of the first lens, second lens, third lens, and fourth lens on the optical axis, respectively.

[0094] The barcode recognition lens in this embodiment meets the conditions in the table below:

[0095] Table 1 Lens Parameter Table

[0096] Surface name Surface type Y radius(mm) Thickness (mm) Refractive index Nd Abbe number Vd surface spherical endless 150.0000 S1 Q-type aspherical surface 3.5752 2.5000 1.544 56.0 S2 Q-type aspherical surface 0.9101 2.2498 S3 Q-type aspherical surface 4.1993 2.4871 1.661 20.4 S4 Q-type aspherical surface -4.1993 1.1145 aperture spherical endless 0.1460 S5 Q-type aspherical surface 2.9139 1.5543 1.544 56.0 S6 Q-type aspherical surface -2.9793 0.1000 S7 Q-type aspherical surface 6.3827 0.4201 1.661 20.4 S8 Q-type aspherical surface 1.9474 0.2380 S9 Q-type aspherical surface 1.9018 0.9207 1.544 56.0 S10 aspherical -6.7439 0.1057 S11 spherical endless 0.6100 1.517 64.2 S12 spherical endless 1.5252 Image spherical endless 0.0000

[0097] Table 2 Surface Parameter Table

[0098] Face number Normalized radius Conical constant 4th order coefficients 6th order coefficients 8th order coefficients 10th order coefficients S1 7.0707 -3.2649 -2.1939 0.6252 -0.1824 0.0291 S2 4.4502 -1.0954 -3.4909 0.2834 0.1733 0.0047 S3 3.4655 -0.2764 0.6954 -0.1576 -0.0452 0.0206 S4 1.0724 6.3540 0.0482 0.0018 8.3461E-05 -2.9356E-05 S5 1.2704 -0.7445 -0.0817 -0.0210 0.0099 0.0065 S6 1.7904 3.3526 -0.6793 0.1311 0.0163 0.0093 S7 1.6895 -124.1089 -1.0769 0.2114 -0.0017 -0.0061 S8 2.2470 -13.4682 -0.1361 0.1913 -0.1697 0.0361 S9 2.4730 -0.6249 -1.2411 0.3570 -0.0922 0.0322 S10 -2.1933 0.0302 -0.0399 0.0261 -0.0092 Face number 10th order coefficients 12th order coefficients 14th order coefficients 16th order coefficients 18th order coefficients 20th order coefficients S1 0.0291 0.0094 -0.0123 0.0107 -0.0038 0.0027 S2 0.0047 -0.1424 0.0614 0.0219 -0.0687 -0.0332 S3 0.0206 -0.0049 -0.0091 -0.0020 -9.223E-05 -0.0003 S4 -2.9356E-05 5.8234E-06 -6.1174E-08 1.3783E-06 -6.9313E-07 9.9074E-08 S5 0.0065 -0.0002 -0.0002 -0.0009 -7.4662E-05 6.9261E-05 S6 0.0093 -0.0128 0.0030 0.0028 0.0042 1.5225E-05 S7 -0.0061 -0.0135 0.0098 0.0035 0.0034 0.0007 S8 0.0361 0.0052 -0.0012 -0.0068 0.0010 -0.0005 S9 0.0322 -0.0197 -0.0025 -0.0015 0.0020 3.2783E-05 S10 -0.0092 0.0019 -0.0002 1.8467E-05 -7.3614E-07 1.2115E-08

Claims

1. A barcode recognition lens, comprising five lenses with optical power, characterized in that: Along the optical axis from the object side to the imaging surface, there are sequentially arranged a first lens (L1), a second lens (L2), an aperture stop (STO), a third lens (L3), a fourth lens (L4), a fifth lens (L5), and a filter (G6); The first lens (L1) is a negative lens made of plastic. The object side is convex and aspherical, and the image side is concave and aspherical. The second lens (L2) is a positive lens made of plastic. The object side is convex and aspherical, and the image side is concave and aspherical. The third lens (L3) is a positive lens made of plastic. The object side is convex and aspherical, and the image side is also convex and aspherical. The fourth lens (L4) is a negative lens made of plastic. The object side is concave and aspherical, and the image side is also concave and aspherical. The fifth lens (L5) is a positive lens made of plastic. Its object side is convex and aspherical, while its image side is convex and spherical. The aperture stop (STO) is located between the second lens and the third lens, and satisfies the following relationship: 0.1 <TDS / f34<0.5; The barcode recognition camera satisfies the following relationship: 8.2 <TTL / f<9.1; Where TDS is the aperture stop diameter, f34 is the focal length of the lens group consisting of the third and fourth lenses; TTL is the on-axis distance from the object side of the first lens to the imaging plane; and f is the effective focal length of the barcode recognition lens.

2. The barcode recognition lens according to claim 1, characterized in that, The following relationship must be satisfied: 1.1 <T12 / f<1.7; 0.71 <T23 / f<0.82; 0.02 <T34 / f<0.11; 0.09 <T45 / f<0.17; Wherein, T12 is the air gap between the first and second lenses on the optical axis, T23 is the air gap between the second and third lenses on the optical axis, T34 is the air gap between the third and fourth lenses on the optical axis, and T45 is the air gap between the fourth and fifth lenses on the optical axis.

3. The barcode recognition lens according to claim 1, characterized in that, The following relationship must be satisfied: -3.0 <f1 / f<-1.5; 7.5 <f2 / f<9.0; 1.7 <f3 / f<2.0; -2.9 <f4 / f<-2.0; 1.3 <f5 / f<1.9; TTL < 15; 105° <FOV<120°; Where f1 is the effective focal length of the first lens, f2 is the effective focal length of the second lens, f3 is the effective focal length of the third lens, f4 is the effective focal length of the fourth lens, f5 is the effective focal length of the fifth lens, TTL is the distance on the optical axis from the object side surface of the first lens to the image plane, and FOV is the maximum field of view of this barcode recognition lens.

4. The barcode recognition lens according to claim 1, characterized in that, The following relationship must be satisfied: 0.28 <T1 / ∑T<0.35; 0.29 <T2 / ∑T<0.34; 0.17 <T3 / ∑T<0.23; 0.03 <T4 / ∑T<0.08; 0.09 <T5 / ∑T<0.15; Where ∑T is the sum of the lens thicknesses of the first lens, second lens, third lens, fourth lens, and fifth lens on the optical axis, and T1, T2, T3, T4, and T5 are the lens thicknesses of the first lens, second lens, third lens, fourth lens, and fifth lens on the optical axis, respectively.

5. The barcode recognition lens according to claim 1, characterized in that, Satisfy the following relation: 0.9 <T3-SA6<1.1; Where T3 is the distance on the optical axis from the object side surface of the third lens to the image side surface of the third lens, and SA6 is the distance on the optical axis from the center of the aspherical surface of the image side surface of the third lens to the maximum effective diameter.

6. The barcode recognition lens according to claim 1, characterized in that, The following relationship must be satisfied: -1.20 <T3-T1<-0.80; -2.50 <T4-T2<-1.97; -0.81 <T5-T3<-0.42; Wherein, T1 is the distance on the optical axis from the object side surface of the first lens to the image side surface of the first lens, T2 is the distance on the optical axis from the object side surface of the second lens to the image side surface of the second lens, T3 is the distance on the optical axis from the object side surface of the third lens to the image side surface of the third lens, T4 is the distance on the optical axis from the object side surface of the fourth lens to the image side surface of the fourth lens, and T5 is the distance on the optical axis from the object side surface of the fifth lens to the image side surface of the fifth lens.

Images