Wide-angle lens and camera device including the lens

Abstract

The present invention discloses a wide-angle lens and a camera device including the lens. The wide-angle lens and the camera device including the lens sequentially include: a first spherical lens, a second spherical lens, a third spherical lens, a fourth spherical lens, a fifth spherical lens, a sixth spherical lens, a seventh spherical lens, an eighth spherical lens and a filter along the optical axis from the object plane to the image plane. The present invention effectively reduces the volume of the short-focus lens by reasonably using double-cemented lenses and limiting the optical focal length of each spherical lens, thereby obtaining an optical lens. The optical lens has the characteristics of compact structure, high resolution, matching chips with more than 8 million pixels, short focal length, large field angle, and strong resistance to environmental temperature changes.

Description

Technical Field

[0001] The present invention relates to the technical field of optical imaging, in particular to a wide-angle lens and a camera device comprising the lens. Background Art

[0002] A wide-angle lens is a photographic lens with a shorter focal length than a standard lens, a larger viewing angle than a standard lens, a longer focal length than a fisheye lens, and a smaller viewing angle than a fisheye lens. It is widely used in traffic monitoring, public place monitoring, security monitoring and other fields to protect people's lives and property. Traditional wide-angle lenses increase the total length and volume of the lens in order to improve the resolution of a large imaging field of view, which increases the cost of the lens, and the large volume affects the space and effect of use; if the total length and volume of the lens are kept small, the resolution of the lens will be greatly reduced. Wide-angle lenses, while taking into account the total length and small volume, bring about the demand for high resolution.

[0003] Chinese patent application number CN200710085652.X discloses a wide-angle lens, comprising a first spherical lens group and a second spherical lens group arranged in sequence from the object side to the image side. The first spherical lens group is composed of a first spherical lens, a second spherical lens and a third spherical lens arranged in sequence from the object side to the image side. The second spherical lens group is composed of a fourth spherical lens and a fifth spherical lens arranged in sequence from the object side to the image side. The refractive powers of the first spherical lens to the fifth spherical lens are negative, negative, positive, positive, and positive in sequence. This wide-angle lens satisfies the following two conditions: 1<D / FG1<3 and 4<D / FG2<6. Wherein, D is the distance from a surface of the first spherical lens facing the object side to the image side; FG1 is the effective focal length of the first spherical lens group; and FG2 is the effective focal length of the second spherical lens group. Since this wide-angle lens uses five spherical lenses and all the spherical lenses are spherical lenses, the cost can be reduced.

[0004] However, the above wide-angle lens still has the following disadvantages:

[0005] 1. The resolution is not high enough to match chips with more than 8 million pixels;

[0006] 2. The structure is not compact enough and requires the addition of multiple spacers for assembly, which increases the difficulty of assembly and the defective rate of the lens. Summary of the invention

[0007] The purpose of the present invention is to solve the deficiencies in the prior art and to provide a wide-angle lens and a camera device including the lens.

[0008] To achieve the above object, the present invention is implemented according to the following technical solutions:

[0009] A wide-angle lens, comprising, along the optical axis from the object plane to the image plane, a first spherical lens, a second spherical lens, a third spherical lens, a fourth spherical lens, a fifth spherical lens, a sixth spherical lens, a seventh spherical lens, an eighth spherical lens and a filter, wherein the first spherical lens, the second spherical lens, the third spherical lens, the fourth spherical lens, the fifth spherical lens, the sixth spherical lens, the seventh spherical lens and the eighth spherical lens are all glass lenses, the first spherical lens has a negative focal length, the object side is convex and the image side is concave, the second spherical lens has a negative focal length, the object side is convex and the image side is concave, the third spherical lens, the fifth spherical lens, the sixth spherical lens, the seventh spherical lens and the eighth spherical lens are all glass lenses, the first ... The focal power of the surface lens is positive, and the object side is convex and the image side is convex; the focal power of the fourth spherical lens is negative, and the object side is concave and the image side is concave; the focal power of the fifth spherical lens is negative, and the object side is concave and the image side is concave; the focal power of the sixth spherical lens is positive, and the object side is convex and the image side is convex; the focal power of the seventh spherical lens is positive, and the object side is convex and the image side is convex; the focal power of the eighth spherical lens is negative, and the object side is concave and the image side is convex; the filter is arranged on the image side of the eighth spherical lens; an aperture is arranged between the fourth spherical lens and the fifth spherical lens;

[0010] The overall focal length of the wide-angle lens is f, the focal length of the first spherical lens is f1, and the focal length of the second spherical lens is f2, which satisfies the relationship: -3.02 <f1 / f<-0.63,-5.82<f2 / f<-2.95。

[0011] As a preferred solution of the present invention, the refractive index of the third spherical lens is nd3, and satisfies the following relationship: 1.52≤nd3≤1.68.

[0012] As a preferred solution of the present invention, the refractive index of the third spherical lens is nd4, and satisfies the following relationship: nd4>1.85.

[0013] As a preferred solution of the present invention, the refractive index of the fifth spherical lens is nd6, and satisfies the following relationship: nd6>1.85.

[0014] As a preferred solution of the present invention, the third spherical lens and the fourth spherical lens are a group of cemented spherical lenses.

[0015] As a preferred solution of the present invention, the fifth spherical lens and the sixth spherical lens are a group of cemented spherical lenses.

[0016] As a preferred solution of the present invention, the seventh spherical lens and the eighth spherical lens are a group of cemented spherical lenses.

[0017] As a preferred solution of the present invention, the absolute values ​​of the curvature radii of the concave surface on the object side and the concave surface on the image side of the fourth spherical lens are equal.

[0018] As a preferred solution of the present invention, the first spherical lens, the second spherical lens and the eighth spherical lens are all meniscus spherical lenses.

[0019] In addition, the present invention also provides a camera device, which includes the wide-angle lens mentioned above.

[0020] Compared with the prior art, the present invention effectively reduces the volume of the short-focus lens by reasonably using double-cemented lenses and limiting the optical focal length of each spherical lens, thereby obtaining an optical lens with compact structure, high resolution, matching chips with more than 8 million pixels, short focal length, large field of view, and strong resistance to environmental temperature changes. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 FIG. 4 is a schematic diagram of a spherical lens according to an embodiment of the present invention.

[0022] Figure 2 This is an MTF analysis diagram at 20 degrees according to an embodiment of the present invention.

[0023] Figure 3 FIG. 4 is a CRA emission angle curve diagram of an embodiment of the present invention.

[0024] Figure 4 4 is a field curvature diagram according to an embodiment of the present invention.

[0025] Figure 5 This is the MTF analysis diagram of the embodiment of the present invention at a low temperature of -20 degrees Celsius.

[0026] Figure 6 This is the MYF analysis diagram of the embodiment of the present invention at a high temperature of 75 degrees. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments. The specific embodiments described herein are only used to explain the present invention and are not used to limit the invention.

[0028] Example 1

[0029] like Figure 1As shown, this embodiment provides a wide-angle lens, which includes, along the optical axis from the object plane to the image plane, a first spherical lens E1, a second spherical lens E2, a third spherical lens E3, a fourth spherical lens E4, a fifth spherical lens E5, a sixth spherical lens E6, a seventh spherical lens E7, an eighth spherical lens E8 and a filter E9. The first spherical lens E1, the second spherical lens E2, the third spherical lens E3, the fourth spherical lens E4, the fifth spherical lens E5, the sixth spherical lens E6, the seventh spherical lens E7 and the eighth spherical lens E8 are all glass lenses. The first spherical lens E1 has a negative focal length, and its object plane side is convex and its image plane side is concave. The second spherical lens E2 has a negative focal length, and its object plane side is convex and its image plane side is concave. The third spherical lens E1 has a negative focal length, and its object plane side is convex and its image plane side is concave. The focal power of the fourth spherical lens E4 is negative, and the object side is concave, and the image side is concave; the focal power of the fifth spherical lens E5 is negative, and the object side is concave, and the image side is concave; the focal power of the sixth spherical lens E6 is positive, and the object side is convex, and the image side is convex; the focal power of the seventh spherical lens E7 is positive, and the object side is convex, and the image side is convex; the focal power of the eighth spherical lens E8 is negative, and the object side is concave, and the image side is convex; the filter E9 is arranged on the image side of the eighth spherical lens E8; an aperture ST is arranged between the fourth spherical lens E4 and the fifth spherical lens E5; the first spherical lens E1, the second spherical lens E2 and the eighth spherical lens E8 are all meniscus lenses;

[0030] Among them: Figure 1 As shown, the object side of the first spherical lens E1 is S1, and the image side is S2, the object side of the second spherical lens E2 is S3, and the image side is S4, the image side of the third spherical lens E3 is S5, the cemented surface of the third spherical lens E3 and the fourth spherical lens E4 is S7, the image side of the fourth spherical lens E4 is S8, the object side of the fifth spherical lens E5 is S9, the cemented surface of the fifth spherical lens E5 and the sixth spherical lens E6 is S10, the image side of the sixth spherical lens E6 is S11, the object side of the seventh spherical lens E7 is S12, the cemented surface of the seventh spherical lens E7 and the eighth spherical lens E8 is S13, and the image side of the eighth spherical lens E8 is S14.

[0031] The overall focal length of the wide-angle lens is f, the focal length of the first spherical lens is f1, and the focal length of the second spherical lens is f2, which satisfies the relationship: -3.02 <f1 / f<-0.63,-5.82<f2 / f<-2.95。

[0032] In this embodiment, the refractive index of the third spherical lens is nd3, and satisfies the following relationship: 1.52≤nd3≤1.68.

[0033] In this embodiment, the refractive index of the third spherical lens is nd4, and it satisfies the following relational expression: nd4 > 1.85.

[0034] In this embodiment, the refractive index of the fifth spherical lens is nd6, and it satisfies the following relational expression: nd6 > 1.85.

[0035] In this embodiment, the third spherical lens and the fourth spherical lens form a set of cemented spherical lenses.

[0036] In this embodiment, the fifth spherical lens and the sixth spherical lens form a set of cemented spherical lenses.

[0037] In this embodiment, the seventh spherical lens and the eighth spherical lens form a set of cemented spherical lenses.

[0038] In this embodiment, the absolute values of the curvature radii of the concave surface on the object side and the concave surface on the image side of the fourth spherical lens are equal.

[0039] In order to verify the optical performance of the wide-angle lens in this embodiment, in one embodiment, the optical system has a FOV of 123.6 degrees, the total focal length of the lens is 3.65 mm, and the lens TTL = 15.97 mm; the parameters of the lens group are listed in Table 1 in sequence.

[0040] Table 1

[0041]

[0042]

[0043] In Table 1: Surf is the surface number, Radius is the curvature radius, Thickness is the lens thickness, Index is the refractive index, ABB is the dispersion coefficient, and EFL-E is the focal length.

[0044] It can be obtained from Table 1 that f1 / f = -1.41, which satisfies the above design of -3.02 < f1 / f < -0.63; f2 / f = -4.46, which satisfies the above design of -5.82 < f2 / f < -2.95; Nd3 = 1.595512, which satisfies the above design of 1.52 ≤ nd3 ≤ 1.68; Nd4 = 2.000694, which satisfies the above design of nd4 > 1.85; Nd6 = 2.000694, which satisfies the above design of nd6 > 1.85.

[0045] As Figure 2As shown, it is the MTF (Modulation Transfer Function) value diagram of the embodiment at 20 degrees Celsius. The MTF value diagram is based on the parameters in Table 1. The measurement of the quality of the optical lens, such as resolution, is the most important. The MTF value must be greater than 0 and less than 1. In the technical field, the higher the MTF value, the better the performance of the lens, that is, the higher the resolution. The variable is the spatial frequency, which is measured by the number of lines that can be presented within a mm range, and its unit is lp / mm. The fixed high frequency (such as 160lp / mm) curve represents the lens resolution characteristic. The higher this curve is, the higher the lens resolution is. The ordinate is the MTF value. The abscissa is the spatial frequency. In addition, at a position deviating from the center of the image field, the MTF values ​​measured by the sinusoidal gratings along the tangent direction and the lines along the radial direction are different. The MTF curve generated by the lines parallel to the diameter is called the sagittal curve, marked as S (Sagittal), and the MTF curve generated by the lines parallel to the tangent is called the meridional curve, marked as T (Meridional). In this way, there are generally two MTF curves, namely the S curve and the T curve. Figure 2 There are multiple groups of MTF variation curves with spatial frequency as the horizontal axis, reflecting that this spherical lens system has a higher resolution and its optical performance is greatly improved compared with the current mainstream optical system.

[0046] Figure 3 This is the main ray angle diagram corresponding to the optical lens, that is, the output angle diagram of the lens. The horizontal coordinate is the field of view of the lens. The leftmost side is the center of the lens, and the rightmost side is the maximum field of view of this lens. The highest field of view angle corresponds to a CRA of about 16 degrees, which is less than 20 degrees. It has a good match with the chip and improves the stability of imaging quality.

[0047] The field curvature diagram corresponding to the visible light part of the spherical lens system. The closer the curve is to the y-axis, the smaller the field curvature. Figure 4 As shown, the field curvature is controlled within the range of -0.05% to 0.05%.

[0048] Figure 5 This is the analytical diagram at minus 20 degrees. Figure 6 This is the resolution diagram at 75 degrees above zero. It can be seen from the figure that the resolution of the optical system remains good at low and high temperatures.

[0049] In summary, the wide-angle lens of the present invention has the characteristics of compact structure, high resolution, matching chips with more than 8 million pixels, short focal length, large field of view, and strong resistance to ambient temperature changes.

[0050] Example 2

[0051] This embodiment provides a camera device, which includes the wide-angle lens mentioned above.

[0052] The technical solution of the present invention is not limited to the above-mentioned specific embodiments. All technical variations made according to the technical solution of the present invention fall within the protection scope of the present invention.

Claims

1. A wide-angle lens, comprising, in order from the object plane to the image plane along the optical axis: The wide-angle lens has a total of eight spherical lenses and a filter, which are the first spherical lens, the second spherical lens, the third spherical lens, the fourth spherical lens, the fifth spherical lens, the sixth spherical lens, the seventh spherical lens, the eighth spherical lens and the filter, characterized in that: the first spherical lens, the second spherical lens, the third spherical lens, the fourth spherical lens, the fifth spherical lens, the sixth spherical lens, the seventh spherical lens and the eighth spherical lens are all glass lenses; the optical focal length of the first spherical lens is negative, the object side is convex, and the image side is concave; the optical focal length of the second spherical lens is negative, the object side is convex, and the image side is concave; the optical focal length of the third spherical lens is positive, the object side is convex, and the image side is convex ; The focal power of the fourth spherical lens is negative, and the object side is concave and the image side is concave; the focal power of the fifth spherical lens is negative, and the object side is concave and the image side is concave; the focal power of the sixth spherical lens is positive, and the object side is convex and the image side is convex; the focal power of the seventh spherical lens is positive, and the object side is convex and the image side is convex; the focal power of the eighth spherical lens is negative, and the object side is concave and the image side is convex; the filter is arranged on the image side of the eighth spherical lens; an aperture is arranged between the fourth spherical lens and the fifth spherical lens; the overall focal length of the wide-angle lens is f, the focal length of the first spherical lens is f1, and the focal length of the second spherical lens is f2, which satisfies the relationship: -3.02 <f1 / f<-0.63,-5.82<f2 / f<-2.95; The first spherical lens, the second spherical lens and the eighth spherical lens are all meniscus lenses.

2. The wide-angle lens according to claim 1, characterized in that: The refractive index of the third spherical lens is nd3, and satisfies the following relationship: 1.52≤nd3≤1.

68.

3. The wide-angle lens according to claim 1, characterized in that: The refractive index of the third spherical lens is nd4, and satisfies the following relationship: nd4>1.

85.

4. The wide-angle lens according to claim 1, characterized in that: The refractive index of the fifth spherical lens is nd6, and satisfies the following relationship: nd6>1.

85.

5. The wide-angle lens according to claim 1, characterized in that: The third spherical lens and the fourth spherical lens are a group of cemented spherical lenses.

6. The wide-angle lens according to claim 1, characterized in that: The fifth spherical lens and the sixth spherical lens are a group of cemented spherical lenses.

7. The wide-angle lens according to claim 1, characterized in that: The seventh spherical lens and the eighth spherical lens form a group of cemented spherical lenses.

8. The wide-angle lens according to claim 1, characterized in that: The concave surface on the object side and the concave surface on the image side of the fourth spherical lens have the same absolute value of curvature radius.

9. A camera device, characterized in that: It comprises a wide-angle lens as described in any one of claims 1 to 8.

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