fixed-focus lens

Abstract

The present invention relates to a fixed-focus lens, comprising: a first lens (L1) with negative optical power, a second lens (L2), a stop (STOP), a third lens (L3), a fourth lens (L4) with positive optical power, a fifth lens (L5) with negative optical power, a sixth lens (L6) with positive optical power, and a protective plate glass (CG), arranged in sequence along an optical axis from the object side to the image side. The optical power of the second lens (L2) is negative or positive, and the optical power of the third lens (L3) is positive or negative. The effective focal length (f3) of the third lens (L3) and the effective focal length (f4) of the fourth lens (L4) satisfy the relationship: 50≤f3 / f4≤13.3. The lens combines high pixel count, small size, and low cost. It does not experience defocusing within a temperature range of 40°C to 80°C and can be used both day and night. It has a resolution of 8 million pixels and can capture images with a maximum field of view of 136°.

Description

Technical Field

[0001] The present invention relates to the technical field of imaging optical systems, and in particular to a fixed-focus lens. Background Art

[0002] With the increasing popularity of security monitoring facilities, fixed-focus lenses are widely used in various fields due to their advantages of high-definition imaging, wide monitoring field of view, and clear imaging under low-light conditions.

[0003] The mainstream surveillance lenses on the market mostly have a resolution of 1080p and a pixel count of 1920*1080. However, with the development of 5G networks, 4K photosensitive chips, and 4K display systems, higher image quality image transmission has become possible. However, the existing high-pixel lenses are limited in variety and relatively expensive.

[0004] Chinese patent CN210142228U discloses a glass-plastic hybrid fixed-focus lens that achieves excellent imaging quality and a resolution of 5 megapixels. However, as the market places higher demands on the imaging performance of fixed-focus lenses, further improvement and continuous research are needed to expand their application range. Summary of the Invention

[0005] To overcome the above-mentioned deficiencies in the prior art, the present invention aims to provide a high-pixel, compact, low-cost, day / night fixed-focus lens that does not experience blur in the temperature range of -40°C to 80°C, has a resolution of eight million pixels, and can capture images with a maximum field of view of 136°.

[0006] To achieve the above-mentioned object, the present invention provides a fixed-focus lens, comprising: a first lens having negative optical power, a second lens, an aperture stop, a third lens, a fourth lens having positive optical power, a fifth lens having negative optical power, a sixth lens having positive optical power, and a protective plate glass, arranged in sequence along the optical axis from the object side to the image side, wherein the optical power of the second lens is negative or positive, and the optical power of the third lens is positive or negative;

[0007] The effective focal length f3 of the third lens and the effective focal length f4 of the fourth lens satisfy the relationship: -50≤f3 / f4≤13.3.

[0008] According to one aspect of the present invention, along the direction from the object side to the image side of the optical axis,

[0009] The second lens is a concave-convex lens;

[0010] The third lens is a convex-concave lens.

[0011] According to one aspect of the present invention, along the direction from the object side to the image side of the optical axis,

[0012] The first lens is a convex-concave aspheric lens;

[0013] The fourth lens is a convex-convex spherical lens;

[0014] The fifth lens is a concave-convex spherical lens;

[0015] The sixth lens is a convex-convex aspheric lens.

[0016] According to one aspect of the present invention, the effective focal length f of the fixed-focus lens and the effective focal length f1 of the first lens satisfy the relationship: -2≤f1 / f≤-1.75.

[0017] According to one aspect of the present invention, the effective focal length f of the fixed-focus lens and the effective focal length f2 of the second lens satisfy the relationship: -9≤f2 / f≤155.

[0018] According to one aspect of the present invention, the effective focal length f of the fixed-focus lens and the effective focal length f3 of the third lens satisfy the relationship: -65≤f3 / f≤17.4.

[0019] According to one aspect of the present invention, the fourth lens and the fifth lens are cemented together to form a doublet lens with positive optical power.

[0020] The effective focal length f of the fixed-focus lens and the effective focal length fb of the doublet lens satisfy the relationship: 1.8≤fb / f≤2.4.

[0021] According to one aspect of the present invention, the effective focal length f of the fixed-focus lens and the effective focal length f6 of the sixth lens satisfy the relationship: 3.5≤f6 / f≤4.

[0022] According to one aspect of the present invention, the first lens, the second lens, the third lens and the sixth lens are all plastic aspherical lenses.

[0023] According to one aspect of the present invention, a relative refractive index temperature coefficient dn / dt of at least one of the fourth lens, the fifth lens, and the sixth lens satisfies the relationship: dn / dt≤3.

[0024] According to one aspect of the present invention, the effective focal length f of the fixed-focus lens and the half-image height h of the fixed-focus lens satisfy the relationship: f / h≤1.2.

[0025] According to one aspect of the present invention, the effective focal length f of the fixed-focus lens and the total length TTL of the fixed-focus lens satisfy the relationship: f / TTL≤0.16.

[0026] According to one aspect of the present invention, at least one of the fourth lens and the fifth lens is made of low-dispersion glass, and the Abbe number of the low-dispersion glass lens satisfies the relationship: VD≥60.

[0027] According to the present invention, by optimizing the positive and negative focal powers of six lenses, placing an aperture stop between the second lens L2 and the third lens L3, and adding a protective flat glass plate CG, this fixed-focus lens achieves a large aperture, an Fno ≤ 1.7, high pixel count, high light throughput, uniform overall illumination, excellent brightness, and no defocusing within a temperature range of -40°C to 80°C, making it suitable for diverse environments. By rationally matching and combining the focal lengths of individual lenses and cemented lenses, aberrations are effectively corrected, further improving system performance. The resolution can reach 8 megapixels, and image capture can be achieved with a maximum field of view of 136°. The lens's image plane height can reach 7.0mm, making it compatible with, but not limited to, 1 / 2.7" sensors. Furthermore, the lens's total optical length is ≤ 22.5mm, ensuring compact size, low cost, and good component and assembly tolerances for excellent manufacturability. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A schematic diagram schematically illustrates the structure of a fixed-focus lens according to Example 1 of the present invention;

[0029] Figure 2 Schematically showing the MTF diagram of the fixed-focus lens of Example 1 of the present invention;

[0030] Figure 3 Schematically showing a Through-Focus-MTF graph of the fixed-focus lens of Example 1 of the present invention at a frequency of 125 lp / mm;

[0031] Figure 4 Schematically showing a Through-Focus-MTF graph of the fixed-focus lens of Example 1 of the present invention at a high temperature of 80° C. and a frequency of 125 lp / mm;

[0032] Figure 5 Schematically showing a Through-Focus-MTF graph of the fixed-focus lens of Example 1 of the present invention at a low temperature of -40°C and a frequency of 125 lp / mm;

[0033] Figure 6 A schematic diagram schematically illustrates the structure of a fixed-focus lens according to Example 2 of the present invention;

[0034] Figure 7 Schematically showing the MTF diagram of the fixed-focus lens according to Example 2 of the present invention;

[0035] Figure 8 Schematically showing a Through-Focus-MTF graph of the fixed-focus lens of Example 2 of the present invention at a frequency of 125 lp / mm;

[0036] Figure 9 Schematically showing a Through-Focus-MTF graph of the fixed-focus lens of Example 2 of the present invention at a high temperature of 80° C. and a frequency of 125 lp / mm;

[0037] Figure 10 Schematically showing a Through-Focus-MTF graph of the fixed-focus lens of Example 2 of the present invention at a low temperature of -40°C and a frequency of 125 lp / mm;

[0038] Figure 11 A schematic diagram schematically illustrates the structure of a fixed-focus lens according to Example 3 of the present invention;

[0039] Figure 12 Schematically showing the MTF diagram of the fixed-focus lens of Example 3 of the present invention;

[0040] Figure 13 Schematically showing a Through-Focus-MTF graph of the fixed-focus lens of Example 3 of the present invention at a frequency of 125 lp / mm;

[0041] Figure 14 Schematically showing a Through-Focus-MTF graph of the fixed-focus lens of Example 3 of the present invention at a high temperature of 80° C. and a frequency of 125 lp / mm;

[0042] Figure 15 Schematically showing a Through-Focus-MTF graph of the fixed-focus lens of Example 3 of the present invention at a frequency of 125 lp / mm at a low temperature of -40°C;

[0043] Figure 16 A schematic diagram schematically illustrates the structure of a fixed-focus lens according to Example 4 of the present invention;

[0044] Figure 17 Schematically showing the MTF diagram of the fixed-focus lens according to Example 4 of the present invention;

[0045] Figure 18 Schematically showing a Through-Focus-MTF graph of the fixed-focus lens of Example 4 of the present invention at a frequency of 125 lp / mm;

[0046] Figure 19 Schematically showing a Through-Focus-MTF graph of the fixed-focus lens of Example 4 of the present invention at a high temperature of 80° C. and a frequency of 125 lp / mm;

[0047] Figure 20Schematically showing a Through-Focus-MTF graph of the fixed-focus lens of Example 4 of the present invention at a frequency of 125 lp / mm at a low temperature of -40°C;

[0048] Figure 21 A schematic diagram schematically illustrates the structure of a fixed-focus lens according to Example 5 of the present invention;

[0049] Figure 22 Schematically showing the MTF diagram of the fixed-focus lens of Example 5 of the present invention;

[0050] Figure 23 Schematically showing a Through-Focus-MTF graph of the fixed-focus lens of Example 5 of the present invention at a frequency of 125 lp / mm;

[0051] Figure 24 Schematically showing a Through-Focus-MTF graph of the fixed-focus lens of Example 5 of the present invention at a high temperature of 80° C. and a frequency of 125 lp / mm;

[0052] Figure 25 The Through-Focus-MTF diagram of the fixed-focus lens according to Example 5 of the present invention at a low temperature of -140° C. and a frequency of 125 lp / mm is schematically shown. DETAILED DESCRIPTION

[0053] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be derived from these drawings without inventive effort.

[0054] When describing the embodiments of the present invention, the orientation or positional relationship expressed by the terms "longitudinal", "transverse", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" are based on the orientation or positional relationship shown in the relevant drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the above terms should not be understood as limiting the present invention.

[0055] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. The embodiments cannot be described one by one here, but the embodiments of the present invention are not limited to the following embodiments.

[0056] like Figure 1As shown, the fixed-focus lens of the present invention includes: a first lens element L1 with negative optical power, a second lens element L2, an aperture stop STOP, a third lens element L3, a fourth lens element L4 with positive optical power, a fifth lens element L5 with negative optical power, a sixth lens element L6 with positive optical power, and a cover glass plate CG, arranged in sequence along the optical axis from the object side to the image side. The second lens element L2 can have either negative or positive optical power, and the third lens element L3 can have either positive or negative optical power. The effective focal length f3 of the third lens element L3 and the effective focal length f4 of the fourth lens element L4 satisfy the relationship: -50 ≤ f3 / f4 ≤ 13.3.

[0057] Along the optical axis from the object side to the image side, the second lens L2 is a meniscus lens, and the third lens L3 is a convex-concave lens. The first lens L1 is a convex-concave aspheric lens; the fourth lens L4 is a convex-convex spherical lens; the fifth lens L5 is a meniscus spherical lens; and the sixth lens L6 is a convex-convex aspheric lens.

[0058] This lens utilizes an optical structure comprised of six lenses with focal powers ranging from negative, negative or positive, positive or negative, positive, negative, and positive. A stop (STOP) is positioned between the second lens element L2 and the third lens element L3, along with a protective flat glass plate CG. The object-side and image-side surfaces of these six lenses are specifically designed as described above, resulting in a large aperture, Fno ≤ 1.7, high light throughput, uniform overall illumination, excellent brightness, and high-pixel imaging. This lens maintains focus within a temperature range of -40°C to 80°C, and is suitable for both day and night use. By optimizing the positive and negative focal powers of each lens, aberrations are effectively corrected, further enhancing system performance. Resolution reaches 8 megapixels, while also enabling image capture with a maximum field of view of 136°.

[0059] The first lens L1, the second lens L2, the third lens L3, and the sixth lens L6 are all plastic aspherical lenses. This fixed-focus lens uses an optical structure consisting of six lenses, an aperture stop, and a protective flat glass plate CG. The four plastic aspherical lenses help reduce costs while also correcting for high and low-temperature imaging.

[0060] The effective focal length f of the fixed-focus lens and the effective focal length f1 of the first lens element L1 satisfy the relationship: -2 ≤ f1 / f ≤ -1.75. The effective focal length f of the fixed-focus lens and the effective focal length f2 of the second lens element L2 satisfy the relationship: -9 ≤ f2 / f ≤ 155. The effective focal length f of the fixed-focus lens and the effective focal length f3 of the third lens element L3 satisfy the relationship: -65 ≤ f3 / f ≤ 17.4. The fourth lens element L4 and the fifth lens element L5 are cemented together to form a positive doublet lens B. The effective focal length f of the fixed-focus lens and the effective focal length fb of the doublet lens B satisfy the relationship: 1.8 ≤ fb / f ≤ 2.4. The effective focal length f of the fixed-focus lens and the effective focal length f6 of the sixth lens element L6 satisfy the relationship: 3.5 ≤ f6 / f ≤ 4. By limiting the focal lengths of the individual lenses in the fixed-focus lens and combining them with the specific design of the cemented lens, chromatic aberration of the optical system can be corrected, thereby achieving higher image quality.

[0061] Furthermore, the effective focal length f of the fixed-focus lens and its half-image height h satisfy the relationship: f / h ≤ 1.2. The effective focal length f of the fixed-focus lens and its total length (TTL) satisfy the relationship: f / TTL ≤ 0.16. This facilitates achieving higher image quality while maintaining a smaller, lower-cost lens. With the protective flat glass CG, the total length of the fixed-focus lens is ≤ 22.5mm. Furthermore, the image plane height of the lens can reach Φ7.0mm, making it compatible with, but not limited to, 1 / 2.7" sensors. This presents broad application prospects and enhances the market competitiveness of the fixed-focus lens of this invention.

[0062] The relative refractive index temperature coefficient dn / dt of at least one of the fourth lens element L4, the fifth lens element L5, and the sixth lens element L6 satisfies the relationship: dn / dt ≤ 3. Furthermore, the fixed-focus lens includes at least one low-dispersion glass lens, and this low-dispersion glass lens is at least one of the fourth lens element L4 and the fifth lens element L5. The Abbe number VD of the low-dispersion glass lens satisfies the relationship: VD ≥ 60. This facilitates the fixed-focus lens optical system to maintain defocus within a temperature range of -40°C to 80°C, making it suitable for various environments.

[0063] In addition, the fixed-focus lens of the present invention has good tolerances for individual components and assembly, and has good manufacturability.

[0064] The following five embodiments are used to specifically illustrate the fixed-focus lens of the present invention through figures and tables. In the following embodiments, the present invention refers to the stop STOP as one surface and the image plane IMAGE as one surface.

[0065] Parameters of various embodiments that specifically meet the above relationship are shown in Table 1 below:

[0066] Relational Example 1 Example 2 Example 3 Example 4 Example 5 -2≤f1 / f≤-1.75 -1.89 -1.77 -1.84 -1.85 -1.98 -9≤f2 / f≤155 -8.87 -8.16 154.1 -7.19 -6.46 -65≤f3 / f≤17.4 17.36 15.69 -64.24 14.92 14.19 -50≤f3 / f4≤13.3 13.29 13.28 -49.7 12.76 12.81 1.8≤fb / f≤2.4 2.38 2.1 2.29 1.99 1.82 3.5≤f6 / f≤4 3.55 3.94 3.71 3.86 3.66 f / h≤1.2 0.87 0.95 0.94 1 1.06 f / TTL≤0.16 0.128 0.141 0.138 0.147 0.156 Fno≤1.7 1.63 1.6 1.65 1.69 1.57

[0067] Table 1

[0068] In various embodiments of the present invention, the plastic aspheric lens of the fixed-focus lens satisfies the following formula:

[0069]

[0070] In the above formula, z is the axial distance from the surface to the vertex at a height h perpendicular to the optical axis along the optical axis; c represents the curvature at the vertex of the aspheric surface; k is the cone coefficient; A4, A6, A8, A 10 、A 12 、A 14 、A 16 ···represent the fourth-order, sixth-order, eighth-order, tenth-order, twelfth-order, fourteenth-order, sixteenth-order···aspheric coefficients respectively.

[0071] Example 1

[0072] See also Figure 1 In this embodiment, the parameters of the fixed-focus lens are as follows:

[0073] F#: 1.63; total lens length: 22.39mm; field of view: 135°.

[0074] The parameters of each lens in the fixed-focus lens of this embodiment include the surface type, curvature radius R value, thickness, refractive index of the material, and Abbe number. S1 to S14 represent each surface of each lens, aperture stop STOP, and protective flat glass CG in the fixed-focus lens, as shown in Table 2 below.

[0075]

[0076]

[0077] Table 2

[0078] The aspheric coefficients of the aspheric lenses of the fixed focus lens of this embodiment include the quadratic surface constant K value of the surface, the fourth-order aspheric coefficient A4, the sixth-order aspheric coefficient A6, the eighth-order aspheric coefficient A8, the tenth-order aspheric coefficient A 10 , 12th-order aspheric coefficient A 12 and the fourteenth-order aspheric coefficient A 14 , as shown in Table 3 below.

[0079] Surface number K <![CDATA[A4]]> <![CDATA[A6]]> <![CDATA[A8]]> <![CDATA[A 10 ]]> <![CDATA[A 12 ]]> <![CDATA[A 14 ]]> S1 -7.06 -5.29E-04 2.31E-05 -2.68E-07 0.00E+00 0.00E+00 0.00E+00 S2 -0.55 -4.00E-03 6.90E-04 -1.35E-04 6.51E-06 0.00E+00 0.00E+00 S3 0.32 2.86E-03 -1.52E-05 3.79E-05 -2.13E-06 0.00E+00 0.00E+00 S4 -50.00 -1.20E-03 5.69E-04 -4.91E-05 4.40E-06 0.00E+00 0.00E+00 S6 0.96 4.36E-03 -1.31E-03 2.62E-04 -2.95E-05 1.42E-06 0.00E+00 S7 2.05 -8.29E-04 1.31E-04 -6.73E-05 6.37E-06 -2.91E-07 0.00E+00 S11 -12.31 1.12E-03 -1.46E-05 6.40E-06 3.71E-07 -8.26E-09 0.00E+00 S12 -15.34 -1.38E-04 -1.27E-05 2.34E-05 -1.25E-06 6.14E-08 0.00E+00

[0080] Table 3

[0081] Depend on Figures 1 to 5Combining the relevant design parameters and specific data in Tables 1 to 3 above, this fixed-focus lens achieves a large aperture, Fno ≤ 1.7, high pixel count, high light throughput, uniform overall illumination, excellent brightness, and no defocusing within a temperature range of -40°C to 80°C, making it suitable for diverse environments. By rationally matching and combining the focal lengths of individual lenses and cemented lens pairs, aberrations are effectively corrected, further improving system performance. Resolution reaches 8 megapixels, while also enabling image capture with a maximum field of view of 136°. The lens's image plane height reaches Φ7.0mm, making it compatible with, but not limited to, 1 / 2.7" sensors. Furthermore, the lens's total optical length is ≤ 22.5mm (with protective flat glass), ensuring compact size, low cost, and excellent component and assembly tolerances for manufacturability.

[0082] Example 2

[0083] See also Figure 6 In this embodiment, the parameters of the fixed-focus lens are as follows:

[0084] F#: 1.6; total lens length: 22.29mm; field of view: 135°.

[0085] The parameters of each lens in the fixed-focus lens of this embodiment include the surface type, curvature radius R value, thickness, refractive index of the material, and Abbe number. S1 to S14 represent each surface of each lens, aperture stop STOP, and protective flat glass CG in the fixed-focus lens, as shown in Table 4 below.

[0086]

[0087]

[0088] Table 4

[0089] The aspheric coefficients of the aspheric lenses of the fixed focus lens of this embodiment include the quadratic surface constant K value of the surface, the fourth-order aspheric coefficient A4, the sixth-order aspheric coefficient A6, the eighth-order aspheric coefficient A8, the tenth-order aspheric coefficient A 10 , 12th-order aspheric coefficient A 12 and the fourteenth-order aspheric coefficient A 14 , as shown in Table 5 below.

[0090] Surface number K <![CDATA[A4]]> <![CDATA[A6]]> <![CDATA[A8]]> <![CDATA[A 10 ]]> <![CDATA[A 12 ]]> <![CDATA[A 14 ]]> S1 -14.993 -9.52E-04 2.47E-05 -2.29E-07 0.00E+00 0.00E+00 0.00E+00 S2 -0.470 -5.47E-03 7.08E-04 -1.23E-04 6.90E-06 0.00E+00 0.00E+00 S3 -0.073 4.92E-03 -1.88E-04 1.88E-05 -8.93E-07 0.00E+00 0.00E+00 S4 -49.998 -2.01E-03 5.72E-04 -4.92E-05 2.57E-06 0.00E+00 0.00E+00 S6 0.803 4.10E-03 -1.33E-03 2.67E-04 -2.87E-05 1.28E-06 0.00E+00 S7 1.898 -1.71E-03 2.19E-04 -5.85E-05 5.89E-06 -3.72E-07 0.00E+00 S11 -11.891 7.86E-04 -5.86E-05 4.81E-06 2.32E-07 1.66E-08 0.00E+00 S12 -21.965 1.91E-04 -7.79E-05 1.65E-05 -1.23E-06 1.01E-07 0.00E+00

[0091] Table 5

[0092] Depend on Figures 6 to 10Combining the relevant design parameters and specific data in Tables 1, 4, and 5 above, this fixed-focus lens achieves a large aperture, Fno ≤ 1.7, high pixel count, high light throughput, uniform overall illumination, excellent brightness, and no defocusing within a temperature range of -40°C to 80°C, making it suitable for diverse environments. By rationally matching and combining the focal lengths of individual lenses and cemented lens pairs, aberrations are effectively corrected, further improving system performance. Resolution reaches 8 megapixels, while also enabling image capture with a maximum field of view of 136°. The lens's image plane height reaches Φ7.0mm, making it compatible with, but not limited to, 1 / 2.7" sensors. Furthermore, the lens's total optical length is ≤ 22.5mm (with protective flat glass), ensuring compact size, low cost, and excellent component and assembly tolerances for manufacturability.

[0093] Example 3

[0094] See also Figure 11 In this embodiment, the parameters of the fixed-focus lens are as follows:

[0095] F#: 1.65; total lens length: 22.4mm; field of view: 134°.

[0096] The parameters of each lens in the fixed-focus lens of this embodiment include the surface type, curvature radius R value, thickness, refractive index of the material, and Abbe number. S1 to S14 represent each surface of each lens, aperture stop STOP, and protective flat glass CG in the fixed-focus lens, as shown in Table 6 below.

[0097] Surface number Surface type Curvature radius R value thickness Refractive index Abbe number S0(OBJ) spherical surface Infinity Infinity S1 Aspheric 18.142 1.13 1.54 55.99 S2 Aspheric 2.561 3.45 S3 Aspheric -4.735 3.00 1.54 55.99 S4 Aspheric -5.676 0.09 S5(STOP) spherical surface Infinity 0.00 S6 Aspheric 8.471 2.74 1.64 23.4 S7 Aspheric 6.942 0.10 S8 spherical surface 4.924 3.50 1.59 60.47 S9 spherical surface -3.375 0.60 1.74 28 S10 spherical surface -10.258 0.09 S11 Aspheric 44.458 1.80 1.54 55.99 S12 Aspheric -7.032 1.20 S13 spherical surface Infinity 0.80 1.52 64.2 S14 spherical surface Infinity 3.90 S15(IMAGE) spherical surface Infinity - - -

[0098] Table 6

[0099] The aspheric coefficients of the aspheric lenses of the fixed focus lens of this embodiment include the quadratic surface constant K value of the surface, the fourth-order aspheric coefficient A4, the sixth-order aspheric coefficient A6, the eighth-order aspheric coefficient A8, the tenth-order aspheric coefficient A 10 , 12th-order aspheric coefficient A 12 and the fourteenth-order aspheric coefficient A 14 ,Down

[0100] As shown in Table 7.

[0101] Surface number K <![CDATA[A4]]> <![CDATA[A6]]> <![CDATA[A8]]> <![CDATA[A 10 ]]> <![CDATA[A 12 ]]> <![CDATA[A 14 ]]> S1 -0.593 -1.00E-03 1.80E-05 -2.67E-07 0.00E+00 0.00E+00 0.00E+00 S2 -0.717 -4.31E-04 6.50E-04 -9.99E-05 7.82E-06 0.00E+00 0.00E+00 S3 0.382 5.87E-04 4.46E-04 -3.92E-06 -1.32E-07 0.00E+00 0.00E+00 S4 -18.912 -3.38E-03 7.07E-04 -5.18E-05 1.73E-06 0.00E+00 0.00E+00 S6 5.498 6.49E-03 -1.40E-03 2.52E-04 -2.86E-05 1.28E-06 0.00E+00 S7 3.728 5.85E-04 2.26E-04 -4.98E-05 5.51E-06 -4.02E-07 0.00E+00 S11 49.892 1.20E-03 6.75E-05 -4.42E-07 9.49E-07 -1.08E-07 0.00E+00 S12 -13.956 -7.08E-04 1.55E-04 2.82E-05 -3.02E-06 9.57E-08 0.00E+00

[0102] Table 7

[0103] Depend on Figures 11 to 15Combining the design parameters and specific data in Tables 1, 6, and 7 above, this fixed-focus lens achieves a large aperture, Fno ≤ 1.7, high pixel count, high light throughput, uniform overall illumination, excellent brightness, and no defocusing within a temperature range of -40°C to 80°C, making it suitable for diverse environments. By rationally matching and combining the focal lengths of individual lenses and cemented lens pairs, aberrations are effectively corrected, further improving system performance. Resolution reaches 8 megapixels, while also enabling image capture with a maximum field of view of 136°. The lens's image plane height reaches Φ7.0mm, making it compatible with, but not limited to, 1 / 2.7" sensors. Furthermore, the lens's total optical length is ≤ 22.5mm (with protective flat glass), ensuring compact size, low cost, and excellent component and assembly tolerances for manufacturability.

[0104] Example 4

[0105] See also Figure 16 In this embodiment, the parameters of the fixed-focus lens are as follows:

[0106] F#: 1.69; total lens length: 22.44mm; field of view: 132°.

[0107] The relevant parameters of each lens of the fixed-focus lens of this embodiment include the surface type, curvature radius R value, thickness, refractive index of the material, and Abbe number. S1 to S14 represent each surface of each lens, aperture stop STOP, and protective flat glass CG in the fixed-focus lens, as shown in Table 8 below.

[0108] Surface number Surface type Curvature radius R value thickness Refractive index Abbe number S0(OBJ) spherical surface Infinity Infinity S1 Aspheric 11.395 0.97 1.51 56 S2 Aspheric 2.496 2.95 S3 Aspheric -4.233 3.00 1.51 56 S4 Aspheric -8.114 0.09 S5(STOP) spherical surface Infinity 0.00 S6 Aspheric 5.483 3.00 1.64 23.4 S7 Aspheric 5.251 0.10 S8 spherical surface 5.049 4.00 1.59 68.4 S9 spherical surface -2.923 0.60 1.75 28.7 S10 spherical surface -7.341 0.09 S11 Aspheric 9.807 1.74 1.51 56 S12 Aspheric -18.349 1.20 S13 spherical surface Infinity 0.80 1.52 64.2 S14 spherical surface Infinity 3.90 S15(IMAGE) spherical surface Infinity - - -

[0109] Table 8

[0110] The aspheric coefficients of the aspheric lenses of the fixed focus lens of this embodiment include the quadratic surface constant K value of the surface, the fourth-order aspheric coefficient A4, the sixth-order aspheric coefficient A6, the eighth-order aspheric coefficient A8, the tenth-order aspheric coefficient A 10 , 12th-order aspheric coefficient A 12 and the fourteenth-order aspheric coefficient A 14 ,Down

[0111] As shown in Table 9.

[0112] Surface number K <![CDATA[A4]]> <![CDATA[A6]]> <![CDATA[A8]]> <![CDATA[A 10 ]]> <![CDATA[A 12 ]]> <![CDATA[A 14 ]]> S1 -16.845 -9.46E-04 2.48E-05 -2.31E-07 0.00E+00 0.00E+00 0.00E+00 S2 -0.512 -2.27E-03 5.75E-04 -1.02E-04 7.58E-06 0.00E+00 0.00E+00 S3 -0.099 4.95E-03 -1.64E-04 1.82E-05 -1.21E-06 0.00E+00 0.00E+00 S4 -49.911 -5.98E-03 5.74E-04 -5.10E-05 2.07E-06 0.00E+00 0.00E+00 S6 0.789 4.09E-03 -1.34E-03 2.66E-04 -2.89E-05 1.28E-06 0.00E+00 S7 1.906 -1.63E-03 2.22E-04 -5.65E-05 6.19E-06 -4.93E-07 0.00E+00 S11 -11.080 7.67E-04 -5.90E-05 5.53E-06 2.95E-07 5.44E-09 0.00E+00 S12 -19.658 1.79E-04 -7.98E-05 1.68E-05 -1.21E-06 9.09E-08 0.00E+00

[0113] Table 9

[0114] Depend on Figures 16 to 20Combining the design parameters and specific data in Tables 1, 8, and 9 above, this fixed-focus lens achieves a large aperture, Fno ≤ 1.7, high pixel count, high light throughput, uniform overall illumination, excellent brightness, and no defocusing within a temperature range of -40°C to 80°C, making it suitable for diverse environments. By rationally matching and combining the focal lengths of individual lenses and cemented lens pairs, aberrations are effectively corrected, further improving system performance. Resolution reaches 8 megapixels, while also enabling image capture with a maximum field of view of 136°. The lens's image plane height reaches Φ7.0mm, making it compatible with, but not limited to, 1 / 2.7" sensors. Furthermore, the lens's total optical length is ≤ 22.5mm (with protective flat glass), ensuring compact size, low cost, and excellent component and assembly tolerances for manufacturability.

[0115] Example 5

[0116] See also Figure 21 In this embodiment, the parameters of the fixed-focus lens are as follows:

[0117] F#: 1.57; total lens length: 22.34mm; field of view: 136°.

[0118] The parameters of each lens in the fixed-focus lens of this embodiment include the surface type, curvature radius R value, thickness, refractive index of the material, and Abbe number. S1 to S14 represent each surface of each lens, aperture stop STOP, and protective flat glass CG in the fixed-focus lens, as shown in Table 10 below.

[0119] Surface number Surface type Curvature radius R value thickness Refractive index Abbe number S0(OBJ) spherical surface Infinity Infinity S1 Aspheric 9.034 0.95 1.53 55.99 S2 Aspheric 2.460 2.87 S3 Aspheric -4.213 2.99 1.53 55.99 S4 Aspheric -8.043 0.09 S5(STOP) spherical surface Infinity 0.00 S6 Aspheric 5.498 2.99 1.64 23.4 S7 Aspheric 5.234 0.10 S8 spherical surface 5.057 3.99 1.59 60.5 S9 spherical surface -2.959 0.60 1.78 25.5 S10 spherical surface -7.355 0.09 S11 Aspheric 9.259 1.77 1.53 55.99 S12 Aspheric -23.955 1.20 S13 spherical surface Infinity 0.80 1.52 64.2 S14 spherical surface Infinity 3.90 S15(IMAGE) spherical surface Infinity - - -

[0120] Table 10

[0121] The aspheric coefficients of the aspheric lenses of the fixed focus lens of this embodiment include the quadratic surface constant K value of the surface, the fourth-order aspheric coefficient A4, the sixth-order aspheric coefficient A6, the eighth-order aspheric coefficient A8, the tenth-order aspheric coefficient A 10 , 12th-order aspheric coefficient A 12 and the fourteenth-order aspheric coefficient A 14 , as shown in Table 11 below.

[0122]

[0123]

[0124] Table 11

[0125] Depend on Figures 21 to 25Combining the relevant design parameters and specific data in Tables 1, 10, and 11, this fixed-focus lens achieves a large aperture, Fno ≤ 1.7, high pixel count, high light throughput, uniform overall illumination, excellent brightness, and no defocusing within a temperature range of -40°C to 80°C, making it suitable for diverse environments. By rationally matching and combining the focal lengths of individual lenses and cemented lens pairs, aberrations are effectively corrected, further improving system performance. Resolution reaches 8 megapixels, while also enabling image capture with a maximum field of view of 136°. The lens's image plane height reaches Φ7.0mm, making it compatible with, but not limited to, 1 / 2.7" sensors. Furthermore, the lens's total optical length is ≤ 22.5mm (with protective flat glass), ensuring compact size, low cost, and excellent component and assembly tolerances for manufacturability.

[0126] The above description is merely one embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A fixed-focus lens, comprising: A total of six lenses are arranged in sequence along the optical axis from the object side to the image side: a first lens (L1) with negative optical power, a second lens (L2), a stop (STOP), a third lens (L3), a fourth lens (L4) with positive optical power, a fifth lens (L5) with negative optical power, a sixth lens (L6) with positive optical power, and a protective plate glass (CG), wherein the second lens (L2) has a negative optical power and the third lens (L3) has a positive optical power; The effective focal length (f3) of the third lens (L3) and the effective focal length (f4) of the fourth lens (L4) satisfy the relationship: 12.76≤f3 / f4≤13.

3.

2. The fixed-focus lens according to claim 1, wherein: Along the direction from the object side to the image side of the optical axis, The second lens (L2) is a meniscus lens; The third lens (L3) is a convex-concave lens.

3. The fixed-focus lens according to claim 1, wherein: Along the direction from the object side to the image side of the optical axis, The first lens (L1) is a convex-concave aspheric lens; The fourth lens (L4) is a convex-convex spherical lens; The fifth lens (L5) is a concave-convex spherical lens; The sixth lens (L6) is a convex-convex aspheric lens.

4. The fixed-focus lens according to claim 1, wherein: The effective focal length (f) of the fixed-focus lens and the effective focal length (f1) of the first lens (L1) satisfy the relationship: -2≤f1 / f≤-1.

75.

5. The fixed-focus lens according to claim 1, wherein: The effective focal length (f) of the fixed-focus lens and the effective focal length (f2) of the second lens (L2) satisfy the relationship: -9≤f2 / f≤-6.

46.

6. The fixed-focus lens according to claim 1, wherein: The effective focal length (f) of the fixed-focus lens and the effective focal length (f3) of the third lens (L3) satisfy the relationship: 14.19≤f3 / f≤17.

4.

7. The fixed-focus lens according to claim 1, wherein: The fourth lens (L4) and the fifth lens (L5) are cemented together to form a doublet lens (B) with positive optical power. The effective focal length (f) of the fixed-focus lens and the effective focal length (fb) of the doublet lens (B) satisfy the relationship: 1.8≤fb / f≤2.

4.

8. The fixed-focus lens according to claim 1, wherein: The effective focal length (f) of the fixed-focus lens and the effective focal length (f6) of the sixth lens (L6) satisfy the relationship: 3.5≤f6 / f≤4.

9. The fixed-focus lens according to claim 1, wherein: The first lens (L1), the second lens (L2), the third lens (L3) and the sixth lens (L6) are all plastic aspheric lenses.

10. The fixed-focus lens according to claim 1, wherein: The relative refractive index temperature coefficient (dn / dt) of at least one of the fourth lens (L4), the fifth lens (L5), and the sixth lens (L6) satisfies the relationship: dn / dt≤3.

11. The fixed-focus lens according to any one of claims 1 to 10, wherein: The effective focal length (f) of the fixed-focus lens and the half-image height (h) of the fixed-focus lens satisfy the relationship: f / h≤1.

2.

12. The fixed-focus lens according to any one of claims 1 to 10, wherein: The effective focal length (f) of the fixed-focus lens and the total length (TTL) of the fixed-focus lens satisfy the relationship: f / TTL≤0.

16.

13. The fixed-focus lens according to any one of claims 1 to 10, wherein: At least one of the fourth lens (L4) and the fifth lens (L5) is made of low-dispersion glass, and the Abbe number (VD) of the low-dispersion glass lens satisfies the relationship: VD≥60.

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