Code scanning optical lens and imaging device

Abstract

The application belongs to the field of optical imaging, camera device and terminal imaging equipment, and specifically discloses a code scanning optical lens, which comprises, from the object side to the image side, an aperture stop STOP, a first lens L1 with negative focal length, a second lens L2 with positive focal length, a third lens L3 with positive focal length, a fourth lens L4 with negative focal length, and a fifth lens L5 with negative focal length, wherein the focal length of the fourth lens L4 is f4, the system focal length of the lens is f, and the field of view is FOV, and the following relationship is satisfied: f4 / f>1.8. The code scanning optical lens can support a 1 / 1.8 inch imaging target surface, and can effectively realize the miniaturization of the lens structure while ensuring high-resolution imaging.

Description

Technical Field

[0001] This invention belongs to the field of optical imaging, camera devices, and terminal imaging equipment, specifically a barcode scanning optical lens and imaging device. Background Technology

[0002] With technological advancements, barcodes and QR codes are becoming increasingly integrated into people's lives, leading to a surge in demand for scanning lenses across various applications. This is particularly true in mobile payments, product information recognition, and information retrieval, where the performance requirements for high-resolution optical lenses are constantly rising. For optical lenses, the use of aspherical lenses significantly reduces lens size and improves product performance, leading to a growing trend of mass-produced lenses incorporating aspherical elements. However, existing barcode scanning lenses still face the following challenges:

[0003] 1. Existing optical lenses have small imaging target sizes and low image resolution.

[0004] 2. The lens has low resolution and the image quality is average;

[0005] 3. The shallow depth of field makes it impossible to achieve clear imaging at different object distances;

[0006] 4. The large number of lenses and the large size of the lens, along with the overall length of the lens, make it impossible to design the entire camera in a miniaturized form.

[0007] Chinese utility model patent CN 218158516 U discloses a barcode scanning lens, which, along the optical axis from the object side to the image side, sequentially includes: a first lens with positive optical power, a second lens with negative optical power, a third lens with positive optical power, a fourth lens with positive optical power, and a protective flat glass. The first, second, third, and fourth lenses are all glass spherical lenses. The object sides of the first and fourth lenses are convex, the second lens is a concave-concave lens, and the third lens is a concave-convex lens. An aperture stop is located on the object side of the first lens. The focal length F4 of the fourth lens and the effective focal length F of the barcode scanning lens satisfy the following relationship: 0.99 ≤ F4 / F ≤ 1.72. This utility model's barcode scanning lens, equipped with only four glass spherical lenses, features a simple structure and low cost, achieving high resolution and low distortion while maintaining high image resolution. However, the overall lens surface area is small, resulting in a low MTF (Mean Transmission Frequency).

[0008] Therefore, there is an urgent need in the market for a barcode scanning lens that combines high resolution with features such as large target area, miniaturization, and low cost. Summary of the Invention

[0009] To address the aforementioned technical problems in the prior art, this invention provides a barcode scanning optical lens, comprising, from the object side to the image side: an aperture stop (STOP), a first lens L1 with negative optical power, a second lens L2 with positive optical power, a third lens L3 with positive optical power, a fourth lens L4 with negative optical power, and a fifth lens L5 with negative optical power. The focal length of the fourth lens L4 is f4, the system focal length of the lens is f, and the field of view is FOV, satisfying the following relationship:

[0010]

[0011] Furthermore, the image side of the fifth lens L5 is also provided with a color filter and an imaging surface.

[0012] Furthermore, the first lens L1 is a meniscus lens; the second lens L2 is a biconvex lens; the third lens L3 is a biconvex lens; the fourth lens L4 is a meniscus lens; and the fifth lens L5 is a meniscus lens.

[0013] Furthermore, the second lens L2 has a concave surface on the object side and a convex surface on the image side; the third lens L3 has a convex surface on both the object side and the image side.

[0014] Furthermore, the central radius of curvature R6 of the image side of the third lens L3 and the central radius of curvature R7 of the object side of the fourth lens L4 satisfy the following:

[0015]

[0016] Furthermore, the system focal length f of the scanning optical lens and the total optical length TTL of the optical lens satisfy the following relationship:

[0017] 2.0≤TTL / f≤2.2 (3).

[0018] Furthermore, the focal lengths f1 of the first lens L1, f2 of the second lens L2, and f3 of the lens L3 of the scanning optical lens satisfy the following formula:

[0019] f1≤-9.5 (4)

[0020] f2≤-7.5 (5)

[0021] f3≤4.2 (6).

[0022] Furthermore, the Abbe number Vd1 of the glass material of the first lens L1, the Abbe number Vd3 of the glass material of the third lens L3, and the Abbe number Vd5 of the glass material of the fifth lens L5 of the scanning optical lens satisfy the following formula:

[0023] Vd1≤33.2 (7)

[0024] Vd3≤60.4 (8)

[0025] Vd5≤53.4 (9).

[0026] Furthermore, the refractive index Nd2 of the glass material of the second lens L2, the refractive index Nd3 of the glass material of the third lens L3, and the refractive index Nd5 of the glass material of the fifth lens L5 satisfy the following relationship:

[0027] Nd2≤1.7 (10)

[0028] Nd3≤1.7 (11)

[0029] Nd5≤1.7 (12).

[0030] An imaging device, the imaging device comprising the aforementioned barcode scanning optical lens.

[0031] Beneficial effects

[0032] The scanning optical lens of this invention can support an imaging target surface of up to 1 / 1.8 inches, effectively miniaturizing the lens structure while ensuring high-resolution imaging. It also has the following characteristics:

[0033] 1. The total mechanical length of the lens shall not exceed 13.4mm;

[0034] 2. The MTF value across the entire field of view reaches 0.5 or higher at 100 lp / mm.

[0035] 3. It has a large depth of field, which can meet the needs of different object distances.

[0036] 4. The lens has fewer elements and is easier to process, resulting in lower costs. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the structure of an optical lens in the prior art;

[0038] Figure 2 This is a schematic diagram of the structure of the optical lens of this application;

[0039] Figure 3 This is an optical transfer function (MTF) curve of Embodiment 1 of the optical lens provided in this application at room temperature in the visible light band;

[0040] Figure 4a and Figure 4b This is a field curvature and distortion diagram of Embodiment 1 of the optical lens provided in this application in the visible light band;

[0041] Figure 5This is a lateral fan pattern in the visible light band of Embodiment 1 of the optical lens provided in this application;

[0042] Figure 6 This is a dot plot of Embodiment 1 of the optical lens provided in this application in the visible light band;

[0043] Figure 7 This is an optical transfer function (MTF) curve of Embodiment 2 of the optical lens provided in this application at room temperature in the visible light band;

[0044] Figure 8a and Figure 8b This is a field curvature and distortion diagram in the visible light band of Embodiment 2 of the optical lens provided in this application;

[0045] Figure 9 This is a lateral fan pattern in the visible light band of Embodiment 2 of the optical lens provided in this application;

[0046] Figure 10 This is a dot plot of Embodiment 2 of the optical lens provided in this application in the visible light band;

[0047] Figure 11 This is a schematic diagram of a specific embodiment of the imaging device provided in this application. Detailed Implementation

[0048] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0049] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a particular order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of the application described herein can be implemented, for example, in orders other than those illustrated or described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0050] like Figure 2As shown, the scanning optical lens of the present invention includes, from the object side to the image side, the following components in sequence: aperture stop STOP, a first lens L1 with negative optical power, a second lens L2 with positive optical power, a third lens L3 with positive optical power, a fourth lens L4 with negative optical power, and a fifth lens L5 with negative optical power.

[0051] The image side of the fifth lens L5 is also equipped with a color filter and an imaging surface.

[0052] Optionally, the first lens L1 is a meniscus lens; the second lens L2 is a biconvex lens; the third lens L3 is a biconvex lens; the fourth lens L4 is a meniscus lens; and the fifth lens L5 is a meniscus lens.

[0053] The fourth lens L4 has a focal length of f4, the system focal length of the lens is f, and the field of view is FOV, satisfying the following relationship:

[0054]

[0055] The second lens L2 has a concave surface on the object side and a convex surface on the image side.

[0056] The third lens L3 has a convex surface on both the object side and the image side.

[0057] The central radius of curvature R6 of the image side of the third lens L3 and the central radius of curvature R7 of the object side of the fourth lens L4 satisfy the following:

[0058]

[0059] The system focal length f of the scanning optical lens and the total optical length TTL of the optical lens satisfy the following relationship:

[0060] 2.0≤TTL / f≤2.2 (3).

[0061] The focal lengths f1 of the first lens L1, f2 of the second lens L2, and f3 of the lens L3 of the scanning optical lens satisfy the following formula:

[0062] f1≤-9.5 (4)

[0063] f2≤-7.5 (5)

[0064] f3≤4.2 (6).

[0065] The Abbe number Vd1 of the glass material of the first lens L1, the Abbe number Vd3 of the glass material of the third lens L3, and the Abbe number Vd5 of the glass material of the fifth lens L5 of the scanning optical lens satisfy the following formula:

[0066] Vd1≤33.2 (7)

[0067] Vd3≤60.4 (8)

[0068] Vd5≤53.4 (9).

[0069] The refractive index Nd2 of the glass material of the second lens L2, the refractive index Nd3 of the glass material of the third lens L3, and the refractive index Nd5 of the glass material of the fifth lens L5 satisfy the following relationship:

[0070] Nd2≤1.7 (10)

[0071] Nd3≤1.7 (11)

[0072] Nd5≤1.7 (12).

[0073] Example 1

[0074] The radius of curvature R, center thickness Tc, refractive index Nd, Abbe constant Vd, and conic coefficient k of each lens in the scanning optical lens of this embodiment 1 satisfy the conditions listed in Table 1:

[0075]

[0076]

[0077] Table 1 Lens Parameter Table

[0078] It should be noted that the mirror serial numbers in Table 1 are Figure 2 The diagram of the scanning optical lens structure shown shows the lens face numbers from left to right.

[0079] The third lens L3 is an aspherical lens, and the equation of an aspherical surface satisfies the following formula:

[0080]

[0081] The aspherical coefficients of the third lens L3 are as follows:

[0082]

[0083] Table 2. Aspherical coefficients.

[0084] The barcode scanning optical lens provided in Embodiment 1 has the following optical technical specifications:

[0085] Total optical length (TTL) ≤ 13.4 mm;

[0086] Lens focal length f: 6.14mm;

[0087] Lens field of view: 63.8°;

[0088] Lens optical distortion: -3.7%;

[0089] The lens system's aperture Fn. is 4.5.

[0090] Lens image size: 1 / 1.8".

[0091] In this embodiment 1, the focal length f4 of the fourth lens L4 of the barcode scanning optical lens, the system focal length f, and the field of view (FOV) satisfy the following: The central radius of curvature R6 of the image side of the third lens L3 and the central radius of curvature R7 of the object side of the fourth lens L4 satisfy the following: The system focal length f of the optical lens and the total optical length TTL of the optical lens satisfy the following relationship: The focal length of the first lens L1 is f1 = -10.31, the focal length of the second lens L2 is f2 = 7.44, and the focal length of the third lens L3 is f3 = 4.18. The Abbe number of the glass material of the first lens L1 is Vd1 = 33.15, the Abbe number of the glass material of the third lens L3 is Vd3 = 60.32, and the Abbe number of the glass material of the fifth lens L5 is Vd5 = 53.35. The refractive index of the glass material of the second lens L2 is Nd2 = 1.58, the refractive index of the glass material of the third lens L3 is Nd3 = 1.62, and the refractive index of the glass material of the fifth lens L5 is Nd5 = 1.53.

[0092] Example 2

[0093] The radius of curvature R, center thickness Tc, refractive index Nd, Abbe constant Vd, and conic coefficient k of each lens in the scanning optical lens of this embodiment 2 satisfy the conditions listed in Table 2:

[0094]

[0095] Table 3 Lens Parameter Table.

[0096] It should be noted that the mirror serial numbers in Table 3 are... Figure 2 The diagram of the optical lens structure shown has the lens face numbers from left to right.

[0097] The third lens L3 is an aspherical lens, and the equation of an aspherical surface satisfies the following formula:

[0098]

[0099] The aspherical coefficients of the third lens L3 are as follows:

[0100]

[0101] Table 4. Aspherical coefficients.

[0102] The barcode scanning optical lens provided in this embodiment 2 has the following optical technical specifications:

[0103] Total optical length TTL≤12.4mm;

[0104] Lens focal length f: 6.12mm;

[0105] Lens field of view: 71.4°;

[0106] Lens optical distortion: -6.0%;

[0107] The lens system's aperture Fn. is 5.0.

[0108] Lens image size: 1 / 1.8".

[0109] In this embodiment 2, the focal length f4 of the fourth lens L4 of the barcode scanning optical lens, the system focal length f, and the field of view (FOV) satisfy the following: The central radius of curvature R6 of the image side of the third lens L3 and the central radius of curvature R7 of the object side of the fourth lens L4 satisfy the following: The system focal length f of the optical lens and the total optical length TTL of the optical lens satisfy the following relationship: The focal length of the first lens L1 is f1 = -9.55, the focal length of the second lens L2 is f2 = 6.71, and the focal length of the third lens L3 is f3 = 3.68. The Abbe number of the glass material of the first lens L1 is Vd1 = 27.58, the Abbe number of the glass material of the third lens L3 is Vd3 = 49.74, and the Abbe number of the glass material of the fifth lens L5 is Vd5 = 34.40. The refractive index of the glass material of the second lens L2 is Nd2 = 1.62, the refractive index of the glass material of the third lens L3 is Nd3 = 1.69, and the refractive index of the glass material of the fifth lens L5 is Nd5 = 1.64.

[0110] In summary, Examples 1 to 2 satisfy the relationships shown in Table 5 below.

[0111]

[0112]

[0113] Table 5: Comprehensive Table of Parameter Relationships

[0114] The optical transfer function is a relatively accurate, intuitive, and common way to evaluate the imaging quality of an imaging system. The higher and smoother the curve, the better the imaging quality of the system and the better it corrects various aberrations (such as spherical aberration, coma, astigmatism, field curvature, axial chromatic aberration, and transverse chromatic aberration).

[0115] like Figure 3 As shown, the optical transfer function (MTF) curve of the scanning optical lens in the visible light region at room temperature is relatively smooth and concentrated, and the average MTF value of the entire field of view (half-image height Y' = 4.4 mm) reaches more than 0.50; it can be seen that the scanning optical lens provided in this embodiment can achieve high imaging requirements.

[0116] like Figure 7 As shown, the optical transfer function (MTF) curve of the target optical lens in the visible light region at room temperature is relatively smooth and concentrated, and the average MTF value of the entire field of view (half-image height Y' = 4.4 mm) reaches more than 0.50; it can be seen that the barcode scanning optical lens provided in this embodiment can achieve high imaging requirements.

[0117] like Figure 4a and Figure 8a As shown, the field curvature of this scanning optical lens is controlled within ±0.05mm. Field curvature is also known as "image field curvature." When a lens has field curvature, the intersection of the entire beam does not coincide with the ideal image point. Although a sharp image point can be obtained at each specific point, the entire image plane is a curved surface. T represents meridional field curvature, and S represents sagittal field curvature. The field curvature curve shows the distance from the current focal plane or image plane to the paraxial focal plane as a function of the field of view coordinates. The meridional field curvature data is the distance from the currently determined focal plane to the paraxial focal plane measured along the Z-axis, and is measured on the meridional (YZ plane). The sagittal field curvature data is the distance measured on a plane perpendicular to the meridional plane. The baseline in the schematic diagram is on the optical axis, and the top of the curve represents the maximum field of view (angle or height). No units are set on the vertical axis because the curve is always normalized using the maximum radial field of view.

[0118] like Figure 4b and Figure 8b As shown, the distortion control of the scanning optical lens is good, within -50%. Figure 4b The curves at multiple wavelengths (0.436 μm, 0.486 μm, 0.546 μm, 0.587 μm, and 0.656 μm) are referenced. Figure 4b The images overlapped. Generally speaking, lens distortion is actually a general term for the inherent perspective distortion of optical lenses, that is, distortion caused by perspective. This distortion is very detrimental to the image quality of a photograph, since the purpose of photography is reproduction, not exaggeration. However, because this is an inherent characteristic of lenses (convex lenses converge light rays, concave lenses diverge light rays), it cannot be eliminated, only improved. Figure 4b and Figure 8bAs can be seen, the distortion of the lens provided in Embodiment 1 of the present invention is -3.7%; the distortion of the lens provided in Embodiment 2 of the present invention is -6.0%. This distortion setting is to balance the focal length, field of view and the size of the corresponding camera target surface. The deformation caused by the distortion can be corrected by post-image processing.

[0119] like Figure 5 and Figure 9 As shown, the curves in the optical sector diagram are relatively concentrated, indicating that the spherical aberration and dispersion of this imaging system are well controlled.

[0120] like Figure 6 and Figure 10 As shown, the imaging system has a small and concentrated spot radius, and the corresponding aberrations and coma are also relatively good.

[0121] In summary, embodiments 1 and 2 of this invention provide a high-resolution barcode scanning lens with a large target area, short TTL, and low cost. By employing five optical lenses with specific structural shapes, arranged sequentially from the object side to the image side, and through the specific allocation and combination of the optical powers of each optical lens, the imaging system achieves excellent imaging characteristics.

[0122] like Figure 11 As shown, the imaging device 10 of this application embodiment includes at least one barcode scanning optical lens 11. Specifically, the barcode scanning optical lens 11 can be the barcode scanning optical lens of embodiments 1 and 2 above, and its specific structure will not be described in detail here.

[0123] The imaging device 10 in this embodiment can be applied to the field of QR code scanning, for example, it can be installed on a mobile phone for QR code payment, product information recognition, information acquisition, etc. In other embodiments, the imaging device 10 can also be applied to other devices, such as tablet computers, information terminals, bank customer terminals, etc.

Claims

1. A barcode scanning optical lens, comprising, from the object side to the image side: The system comprises an aperture stop (STOP), a first lens L1 with negative optical power, a second lens L2 with positive optical power, a third lens L3 with positive optical power, a fourth lens L4 with negative optical power, and a fifth lens L5 with negative optical power. The first lens L1 is a meniscus lens with its convex surface facing the image side; the second lens L2 is a biconvex lens; the third lens L3 is a biconvex lens; the fourth lens L4 is a lens with a concave object side; and the fifth lens L5 is a meniscus lens with its convex surface facing the image side. The feature is that the focal length of the fourth lens L4 is... The system focal length of the lens is The field of view is It satisfies the following relationship: （1）。 2. The scanning optical lens according to claim 1, characterized in that: The image side of the fifth lens L5 is also equipped with a color filter and an imaging surface.

3. The scanning optical lens according to claim 1, characterized in that: The central radius of curvature R6 of the image side of the third lens L3 and the central radius of curvature R7 of the object side of the fourth lens L4 satisfy the following: （2）。 4. The scanning optical lens according to claim 1, characterized in that: The system focal length of the scanning optical lens is: The following conditions must be met between the total optical length (TTL) of the optical lens and the total optical length (TTL) of the optical lens: （3）。 5. The scanning optical lens according to claim 1, characterized in that: The focal lengths f1 of the first lens L1, f2 of the second lens L2, and f3 of the lens L3 of the scanning optical lens satisfy the following formula: f1≤-9.5 （4） f2≤-7.5 （5） f3≤4.2 （6）。 6. The scanning optical lens according to claim 1, characterized in that: The Abbe number Vd1 of the glass material of the first lens L1, the Abbe number Vd3 of the glass material of the third lens L3, and the Abbe number Vd5 of the glass material of the fifth lens L5 of the scanning optical lens satisfy the following formula: Vd1≤33.2 (7) Vd3≤60.4 (8) Vd5≤53.4 (9).

7. The scanning optical lens according to claim 1, characterized in that: The refractive index Nd2 of the glass material of the second lens L2, the refractive index Nd3 of the glass material of the third lens L3, and the refractive index Nd5 of the glass material of the fifth lens L5 satisfy the following relationship: Nd2≤1.7 (10) Nd3≤1.7 (11) Nd5≤1.7 (12).

8. An imaging device, characterized in that, The imaging device includes the barcode scanning optical lens as described in any one of claims 1 to 7.

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