Optical lens and imaging device
By designing three fixed-position optical lenses and infrared filters, the problem of high cost of lenses in traditional code scanning equipment is solved, and the effect of small number of lenses, low cost and good imaging effect is achieved. It is suitable for supermarkets and other scenarios.
Patent Information
- Application Number
- CN202422287384.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-18
- Publication Date
- 2025-07-01
- Estimated Expiration
- 2034-09-18
AI Technical Summary
Due to the large number of lenses and high cost of traditional code scanning equipment, it is difficult to meet the needs of low cost and not affect the imaging effect.
An optical lens including three fixed lenses and infrared filters is designed, the lenses are the first lens, the second lens and the third lens respectively. Through reasonable focal length and curvature configuration, the imaging performance of the lens is optimized.
It realizes optical lenses with small number of lenses, low cost and good imaging effects, and is suitable for supermarkets and other stores that require fixed scanning lenses.
Smart Images
Figure CN223051569U_ABST
Abstract
Description
Technical Field
[0001] This application relates to an optical lens and an imaging device, and particularly to an optical lens and an imaging device including three lenses. Background Art
[0002] In recent years, the use of two-dimensional codes has been increasing day by day. They are not only widely used in shopping malls, but also appear on intelligent products such as household appliances or remotely controllable products, enabling functions such as product information acquisition, product information recognition, mobile payment, wireless short-range or long-range control, etc. The lenses of traditional barcode scanning devices have a relatively high cost due to the large number of lenses. Therefore, there is an urgent need for a barcode scanning optical lens with a lower cost and no impact on the imaging effect. Summary of the Invention
[0003] The purpose of this application is to provide an optical lens and an imaging device including three lenses.
[0004] An optical lens includes three lenses with fixed positions and an infrared filter. The three lenses are the first lens, the second lens, and the third lens respectively. The first lens to the third lens and the infrared filter are arranged in sequence from the object side to the image side along the optical axis. Among them, the object-side surface of the first lens is convex near the optical axis, and the image-side surface is concave near the optical axis. The object-side surface of the second lens is convex near the optical axis, and the image-side surface is convex near the optical axis. The object-side surface of the third lens is concave near the optical axis, and the image-side surface is convex near the optical axis. Preferably, the three lenses do not contact each other or only contact at the edges, are immovable relative to each other, and the object-side surface and the image-side surface of each lens are aspherical surfaces, which can effectively reduce the lens thickness. At the same time, the optical lens satisfies -1.84 < f1 < -0.83, 0.29 < f2 < 0.51, where f1 is the focal length of the first lens and f2 is the focal length of the second lens. By controlling their magnitudes, the optical lens can be ensured to have good imaging performance characteristics. The configuration of the first lens enables it to effectively balance low-order aberrations. The configuration of the second lens enables it to facilitate the elimination of aberrations generated by the first lens. The configuration of the third lens helps to move the principal point of the optical imaging system away from the image-side end, thereby effectively shortening the overall length of the optical imaging system, effectively correcting paraxial spherical aberration, and reducing astigmatism field curvature at the periphery. The first lens cooperates with the second lens and the third lens, which can effectively correct paraxial spherical aberration, reduce astigmatism field curvature at the periphery, and effectively shorten the overall length of the optical imaging system, enabling the optical lens to have better light converging ability.
[0005] The optical lens also optionally satisfies 0.5 < CT3 / T34 < 4.7, where CT3 is the thickness of the third lens on the optical axis, and T34 is the distance between the third lens and the infrared filter on the optical axis. Controlling the ratio of CT3 / T34 can reduce the assembly difficulty of the camera lens.
[0006] The optical lens also optionally satisfies -2.7 < f1 / f < -1.3, 0.4 < f2 / f < 0.85, -56.1 < f3 / f < 2.6, where f is the total effective focal length of the optical lens and f3 is the focal length of the third lens. Controlling the ratio can avoid excessive optical powers of the first, second, and third lenses, resulting in a low-sensitivity and good-imaging-quality optical lens, while also giving the optical lens a short optical length.
[0007] The optical lens also optionally satisfies 0.8 < R32 / R31 < 1.31, where R31 is the curvature of the object-side surface of the third lens and R32 is the curvature of the image-side surface of the third lens. Controlling the ratio can effectively reduce chromatic aberration and prevent the image formed by the lens from being purple-shifted or red-shifted.
[0008] The optical lens also optionally satisfies 0.08 < CT1 / TTL < 0.15, 0.125 < CT2 / TTL < 0.19, where TTL is the distance from the object-side surface of the first lens at the near optical axis to the image plane of the optical lens, CT1 is the thickness of the first lens on the optical axis, and CT2 is the thickness of the second lens on the optical axis. Controlling the above ratios can appropriately distribute the spacing between the lenses, reduce the total length of the camera lens, and lower the assembly difficulty of the camera lens, enabling the assembly process to proceed smoothly and simply.
[0009] The optical lens also optionally satisfies -0.28 < (R21 + R22) / (R21 - R22) < 0.045, where R21 is the curvature of the object-side surface of the second lens and R22 is the curvature of the image-side surface of the second lens. Controlling the ratio can effectively reduce the stray light generated by the second lens.
[0010] The optical lens also optionally satisfies 0.2 < (CT2 + CT3) / TTL < 0.3, where CT2 is the thickness of the second lens on the optical axis. Controlling the above value can give the lens group a good optical imaging effect.
[0011] The optical lens also optionally satisfies 80 < FOV < 91, where FOV is the maximum field of view of the optical lens, that is, the lens group has a good field of view range.
[0012] The optical lens also optionally includes a diaphragm disposed near the object-side surface of the second lens. If the diaphragm is disposed on the object-side surface of the first lens, it is difficult to achieve a large field of view angle and wide-angle imaging; if the diaphragm is disposed on the object-side surface of the third lens, it is difficult to optimize aberrations such as spherical aberration, coma, and astigmatism, and it is difficult to achieve high image quality; if the diaphragm is disposed on the object-side surface of the second lens, it is easy to achieve wide-angle imaging and high image quality.
[0013] The imaging device of the present application includes the above optical lens and an imaging element for converting the optical image formed by the optical lens into an electrical signal. The imaging device has the advantages of fewer lens elements, being lightweight, and having a relatively low cost, while also having good light-gathering ability. The optical lens and imaging device of the present application are particularly suitable for stores such as supermarkets that require a fixed code-scanning lens to be installed. Description of the Drawings
[0014] Figure 1 It is a schematic structural diagram of the optical lens according to the first embodiment of the present application.
[0015] Figure 2 It is a graph of astigmatism and distortion of the optical lens according to the first embodiment of the present application.
[0016] Figure 3 It is a graph of lateral chromatic aberration of the optical lens according to the first embodiment of the present application.
[0017] Figure 4 It is a schematic structural diagram of the optical lens according to the second embodiment of the present application.
[0018] Figure 5 It is a graph of astigmatism and distortion of the optical lens according to the second embodiment of the present application.
[0019] Figure 6 It is a graph of lateral chromatic aberration of the optical lens according to the second embodiment of the present application.
[0020] Figure 7 It is a schematic structural diagram of the optical lens according to the third embodiment of the present application.
[0021] Figure 8 It is a graph of astigmatism and distortion of the optical lens according to the third embodiment of the present application.
[0022] Figure 9 It is a graph of lateral chromatic aberration of the optical lens according to the third embodiment of the present application.
[0023] Figure 10 It is a schematic structural diagram of the optical lens according to the fourth embodiment of the present application.
[0024] Figure 11 It is a graph of astigmatism and distortion of the optical lens according to the fourth embodiment of the present application.
[0025] Figure 12 It is a graph of lateral chromatic aberration of the optical lens according to the fourth embodiment of the present application.
[0026] Figure 13 It is a schematic structural diagram of the optical lens according to the fifth embodiment of the present application.
[0027] Figure 14 It is a graph of astigmatism and distortion of the optical lens according to the fifth embodiment of the present application.
[0028] Figure 15This is the lateral chromatic aberration diagram of the optical lens according to the fifth embodiment of the present application. Detailed implementation manners
[0029] In the description of the present application, the object side of the lens refers to the side of the lens facing the object to be photographed, and the image side refers to the side of the lens facing the imaging surface. When making a tangent plane at any point on the surface passing through the object side of the lens, the object side surface is always on the image side of the tangent plane, and its radius of curvature is positive, then the object side surface of the lens is a convex surface; otherwise, the object side surface of the lens is a concave surface. When making a tangent plane at any point on the surface passing through the image side of the lens, the image side surface is always on the object side of the tangent plane, and its radius of curvature is negative, then the image side surface of the lens is a convex surface; otherwise, the image side surface of the lens is a concave surface. If a tangent plane is made at any point on the surface passing through the object side or the image side of the lens, and the object side surface or the image side surface has parts on both the image side and the object side of the tangent plane, then there are inflection points on this surface. The judgment of the convexity and concavity of the object side and the image side surfaces near the optical axis still applies to the above method.
[0030] In addition, the aspheric curve equations of each aspheric lens are expressed as follows:
[0031]
[0032] Among them, Z is the distance sagitta from the origin of the aspheric surface when the aspheric surface is at a position with a height of r along the optical axis direction, c is the paraxial curvature of the aspheric surface (the radius of curvature R = 1 / c, that is, the reciprocal of the curvature); k is the conic coefficient; Ai is the i-th order coefficient of the aspheric surface. The high-order coefficients applied in the present application are A4, A6, A8, A 10 、A 12 、A 14 、A 16 .
[0033] The imaging device of the present application mainly includes a housing with a through hole, an optical lens assembled in the housing, and an imaging element for converting the optical image formed by the optical lens into an electrical signal. The imaging element is arranged on the imaging surface of the optical lens. The optical lens includes three lenses with optical powers fixed in sequence from the object side to the image side along the optical axis, namely the first lens, the second lens, and the third lens.
[0034] The first lens has a negative refractive power. Its object side surface is convex near the optical axis, and its image side surface is concave near the optical axis. The configuration of the first lens enables it to effectively balance low-order aberrations.
[0035] The second lens has a positive refractive power. Its object side surface is convex near the optical axis, and its image side surface is convex near the optical axis. The configuration of the second lens enables it to facilitate the elimination of the aberrations generated by the first lens.
[0036] The third lens has a positive refractive power. Its object-side surface is concave near the optical axis, and its image-side surface is convex near the optical axis. This configuration helps to move the principal point of the optical photography system away from the image-side end, thereby effectively shortening the overall length of the optical imaging system, effectively correcting the paraxial spherical aberration, and reducing the astigmatic field curvature at the periphery at the same time.
[0037] Preferably, the three lenses do not contact each other or only contact at the edges, are immovable relative to each other, and the object-side surface and the image-side surface of each lens are aspherical surfaces, which can effectively reduce the lens thickness. At the same time, the optical lens satisfies 0.83 < f1 < 1.84 and -0.51 < f2 < -0.29, where f1 is the focal length of the first lens and f2 is the focal length of the second lens. The values of f1 and f2 can ensure that the optical lens has good imaging characteristics.
[0038] The first lens, the second lens, and the third lens cooperate with each other to enable the optical lens to have better light converging ability.
[0039] The following further describes specific embodiments of the imaging device applicable to the above embodiments with reference to the accompanying drawings.
[0040] Embodiment 1:
[0041] The imaging device of Embodiment 1 mainly includes a housing having a through hole, an optical lens 10 assembled in the housing, and an imaging element for converting the optical image formed by the optical lens 10 into an electrical signal. Among them, as Figure 1 shown, the optical lens 10 mainly includes three lenses arranged at intervals. Specifically, in order from the object side to the image side, it includes: a first lens 101, a diaphragm 105, a second lens 102, a third lens 103, and a filter 104. The diaphragm 105 is disposed near the object-side surface of the second lens 102. Figure 1 The reference numeral 111 in the figure indicates the imaging surface of the optical lens 10, and the surface of the imaging element of the imaging device should be located on the imaging surface.
[0042] The structural settings of the optical lens 10 in Embodiment 1 enable it to satisfy the parameters listed in Table 1-1, Table 1-2, and Table 1-3.
[0043] Among them, Table 1-1 is the basic parameters of the optical lens in Embodiment 1, including the total effective focal length f of the optical lens, the relative aperture FNO of the optical lens, the maximum field of view FOV of the optical lens, the radius of curvature (unit: mm), the thickness (unit: mm), the lens material, the lens refractive index and dispersion coefficient, and the focal length of the lens (unit: mm). The surface numbers are numbered from the object side to the image side.
[0044] Table 1-2 is the aspherical coefficients of each lens in Embodiment 1, and these coefficients all satisfy the above aspherical formula (1).
[0045] Table 1-3 shows the values of the conditions satisfied by the optical lens in Embodiment 1.
[0046] Attached Figure 2 shows the astigmatism and distortion curves of the optical lens of Embodiment 1. Figure 3 shows the spherical aberration curve of the optical lens of Embodiment 1.
[0047]
[0048]
[0049] Embodiment 2:
[0050] The imaging device of Embodiment 2 mainly includes a housing with a through hole, an optical lens assembled in the housing, and an imaging element for converting the optical image formed by the optical lens into an electrical signal. Among them, as Figure 4 shown, the optical lens 20 mainly includes three lenses arranged at intervals. Specifically, from the object side to the image side, it sequentially includes: a first lens 201, a diaphragm 205, a second lens 202, a third lens 203, and a filter 204. The diaphragm 205 is arranged at a position close to the object side surface of the second lens 202. Figure 4 The reference numeral 211 in the figure indicates the imaging surface of the optical lens 20, and the surface of the imaging element of the imaging device should be located on the imaging surface.
[0051] The structural settings of the optical lens 20 in Embodiment 2 are such that it satisfies the parameters listed in Table 2-1, Table 2-2, and Table 2-3.
[0052] Among them, Table 2-1 shows the basic parameters of the optical lens in Embodiment 2, including the total effective focal length f of the optical lens, the relative aperture FNO of the optical lens, the maximum field of view FOV of the optical lens, the radius of curvature (unit: mm), the thickness (unit: mm), the refractive index and dispersion coefficient of the lens material, and the focal length of the lens (unit: mm). The surface numbers are numbered from the object side to the image side.
[0053] Table 2-2 shows the aspherical coefficients of each lens in Embodiment 2, and these coefficients all satisfy the above aspherical formula (1).
[0054] Table 2-3 shows the values of the conditions satisfied by the optical lens in Embodiment 2.
[0055] Attached Figure 5 shows the astigmatism and distortion curves of the optical lens of Embodiment 2. Figure 6 shows the spherical aberration curve of the optical lens of Embodiment 2.
[0056]
[0057]
[0058] Example 3:
[0059] The imaging device of Example 3 mainly includes a housing with a through hole, an optical lens assembled in the housing, and an imaging element for converting the optical image formed by the optical lens into an electrical signal. Among them, as Figure 7 shown, the optical lens 30 mainly includes three lenses arranged at intervals. Specifically, in order from the object side to the image side, it includes: a first lens 301, a diaphragm 305, a second lens 302, a third lens 303, and a filter 304. The diaphragm 305 is arranged at a position close to the object side surface of the second lens 302. Figure 7 The reference numeral 311 in the figure indicates the imaging surface of the optical lens 30, and the surface of the imaging element of the imaging device should be located on the imaging surface.
[0060] The structural settings of the optical lens 30 of Example 3 enable it to meet the parameters listed in Table 3-1, Table 3-2, and Table 3-3.
[0061] Among them, Table 3-1 is the basic parameters of the optical lens of Example 3, including the total effective focal length f of the optical lens, the relative aperture FNO of the optical lens, the maximum field of view FOV of the optical lens, the radius of curvature (unit: mm), the thickness (unit: mm), the refractive index and dispersion coefficient of the lens material, and the focal length of the lens (unit: mm). The surface serial numbers are numbered from the object side to the image side.
[0062] Table 3-2 is the aspherical coefficients of each lens in Example 3, and these coefficients all satisfy the above aspherical formula (1).
[0063] Table 3-3 is the value of the conditions satisfied by the optical lens in Example 3.
[0064] Appendix Figure 8 shows the astigmatism and distortion curves of the optical lens of Example 3. Figure 9 shows the spherical aberration curve of the optical lens of Example 3.
[0065]
[0066]
[0067] Example 4:
[0068] The imaging device of Example 4 mainly includes a housing with a through hole, an optical lens assembled in the housing, and an imaging element for converting the optical image formed by the optical lens into an electrical signal. Among them, as Figure 10As shown in the figure, the optical lens 40 mainly includes three lenses arranged at intervals. Specifically, from the object side to the image side, it sequentially includes: the first lens 401, the aperture stop 405, the second lens 402, the third lens 403, and the filter 404. The aperture stop 405 is arranged at a position close to the object-side surface of the second lens 402. Figure 10 The imaging surface of the optical lens 40 is indicated by the reference numeral 311, and the surface of the imaging element of the imaging device should be located on the imaging surface.
[0069] The structural arrangement of the optical lens 40 in the fourth embodiment enables it to satisfy the parameters listed in Table 4-1, Table 4-2, and Table 4-3.
[0070] Among them, Table 4-1 shows the basic parameters of the optical lens in the fourth embodiment, including the total effective focal length f of the optical lens, the relative aperture FNO of the optical lens, the maximum field of view FOV of the optical lens, the radius of curvature (unit: mm), the thickness (unit: mm), the refractive index and dispersion coefficient of the lens material, and the focal length of the lens (unit: mm). The surface numbers are numbered from the object side to the image side.
[0071] Table 4-2 shows the aspherical coefficients of each lens in the fourth embodiment, and these coefficients all satisfy the above aspherical formula (1).
[0072] Table 4-3 shows the values of the conditions satisfied by the optical lens in the fourth embodiment.
[0073] Appendix Figure 11 Shows the astigmatism and distortion curves of the optical lens in the fourth embodiment. Figure 12 Shows the spherical aberration curve of the optical lens in the fourth embodiment.
[0074]
[0075] Embodiment Five:
[0076] The imaging device in the fifth embodiment mainly includes a housing with a through hole, an optical lens assembled in the housing, and an imaging element for converting the optical image formed by the optical lens into an electrical signal. Among them, as Figure 13 shown, the optical lens 50 mainly includes three lenses arranged at intervals. Specifically, from the object side to the image side, it sequentially includes: the first lens 501, the aperture stop 505, the second lens 502, the third lens 503, and the filter 504. The aperture stop 505 is arranged at a position close to the object-side surface of the second lens 502. Figure 13 The imaging surface of the optical lens 50 is indicated by the reference numeral 511, and the surface of the imaging element of the imaging device should be located on the imaging surface.
[0077] The structural arrangement of the optical lens 50 in the fifth embodiment enables it to satisfy the parameters listed in Table 5-1, Table 5-2, and Table 5-3.
[0078] Among them, Table 5-1 shows the basic parameters of the optical lens in Embodiment 5, including the total effective focal length f of the optical lens, the relative aperture FNO of the optical lens, the maximum field of view FOV of the optical lens, the radius of curvature (unit: mm), the thickness (unit: mm), the refractive index and dispersion coefficient of the lens material, and the focal length of the lens (unit: mm). The surface numbers are numbered from the object side to the image side.
[0079] Table 5-2 shows the aspheric coefficients of each lens in Embodiment 5, and these coefficients all satisfy the above aspheric formula (1).
[0080] Table 5-3 shows the values of the conditions satisfied by the optical lens in Embodiment 5.
[0081] Appendix Figure 14 shows the astigmatism and distortion curves of the optical lens in Embodiment 5. Figure 15 shows the spherical aberration curve of the optical lens in Embodiment 5.
[0082]
[0083]
[0084] In summary, Embodiments 1 to 5 respectively satisfy the relationships shown in Table 6 below.
[0085] Table 6 Parameter comparison of the optical lenses of the imaging devices in five embodiments
[0086]
[0087] In summary, the above optical lens adopts a three-lens structure. Through reasonable material selection and refractive power matching, when specific conditions are met, the imaging device has the advantages of fewer lens elements, light weight, and lower cost, and at the same time has better light converging ability.
[0088] In addition, terms such as "first", "second",... are only used to distinguish one feature from another, and do not represent any limitation on the feature.
[0089] Although the description of the present application is made in combination with the above specific embodiments, it is obvious that those skilled in the art can make many substitutions, modifications and changes based on the above content. Therefore, all such substitutions, improvements and changes are included in the spirit and scope of the appended claims.
Claims
1. An optical lens, comprising three lenses with fixed positions, namely a first lens, a second lens and a third lens, and further comprising an infrared filter. The first lens to the third lens and the infrared filter are sequentially arranged along the optical axis from the object side to the image side. It is characterized in that: The object-side surface of the first lens is convex near the optical axis, and the image-side surface is concave near the optical axis. The image-side surface of the second lens is convex near the optical axis, and the image-side surface is convex near the optical axis. The object-side surface of the third lens is concave near the optical axis, and the image-side surface is convex near the optical axis. The object-side surface and the image-side surface of each of the first to third lenses are aspherical surfaces. The optical lens satisfies -1.84 < f1 < -0.83, 0.29 < f2 < 0.51, where f1 is the focal length of the first lens and f2 is the focal length of the second lens.
2. The optical lens according to claim 1, wherein: The imaging lens satisfies 0.5 < CT3 / T34 < 4.7, where CT3 is the thickness of the third lens on the optical axis and T34 is the distance between the third lens and the infrared filter on the optical axis.
3. The optical lens according to claim 1, wherein: The imaging lens satisfies -2.7 < f1 / f < -1.3, 0.4 < f2 / f < 0.85, -56.1 < f3 / f < 2.6, where f is the total effective focal length of the optical lens and f3 is the focal length of the third lens.
4. The optical lens according to claim 1, wherein: The imaging lens satisfies 0.8 < R32 / R31 < 1.31, where R31 is the curvature of the object-side surface of the third lens and R32 is the curvature of the image-side surface of the third lens.
5. The optical lens according to claim 1, wherein: The imaging lens satisfies 0.08 < CT1 / TTL < 0.
15. 0.125 < CT2 / TTL < 0.19, where TTL is the distance from the object-side surface of the first lens near the optical axis to the image plane of the optical lens, CT1 is the thickness of the first lens on the optical axis, and CT2 is the thickness of the second lens on the optical axis.
6. The optical lens according to claim 1, wherein: The imaging lens satisfies -0.28 < (R21 + R22) / (R21 - R22) < 0.045, where R21 is the curvature of the object-side surface of the second lens and R22 is the curvature of the image-side surface of the second lens.
7. The optical lens according to claim 1, wherein: The imaging lens satisfies 0.2 < (CT2 + CT3) / TTL < 0.3, where CT2 is the thickness of the second lens on the optical axis.
8. The optical lens according to claim 1, wherein: The imaging lens satisfies the following condition: 80 < FOV < 91, where FOV is the maximum field of view angle of the optical lens.
9. The optical lens according to claim 1, wherein: It further includes a diaphragm disposed near the object-side surface of the second lens.
10. An imaging device, characterized in that: It includes the optical lens according to any one of claims 1-9.