TWI546566B - Wide-angle lens - Google Patents

Description

Wide-angle lens

The present invention relates to a wide-angle lens.

Digital cameras and mobile phones are constantly moving toward high-definition and lightweight, making the demand for miniaturization and high-resolution wide-angle lenses greatly increased. Most of the conventional three-lens imaging lenses use a low Abbe number lens combined with two high Abbe Number lenses, the lens closest to the image side has a low Abbe coefficient (Abbe Number), the other two lenses have a high Abbe Number and a front aperture for lens miniaturization and resolution. However, the conventional imaging lens described above has a small viewing angle, and its resolution deteriorates when the temperature reaches 60 degrees Celsius. When the distance between the subject and the lens is as close as 300 mm, the resolution is also deteriorated, so it is necessary to have Another architecture lens design can enhance the characteristics of the above imaging lens to meet today's needs.

In view of this, the main object of the present invention is to provide a wide-angle lens with a short total lens length and a large viewing angle, but still has good optical performance. When the temperature reaches 60 degrees Celsius or the shooting distance is 30 mm, the lens resolution can also be fulfil requirements.

The wide-angle lens of the present invention sequentially includes a first lens, a second lens, an aperture, and a third lens from the object side to the image side along the optical axis. The first lens is a biconcave lens having a negative refractive power. The second lens is a convex-concave lens having a positive refractive power, and the convex surface of the second lens faces the object side concave surface toward the image side. The third lens has a positive refractive power and includes a convex surface toward the image side. The wide-angle lens satisfies the following condition: 2.9 < D _L1 / D _L2 <3.1; wherein D _L1 is the effective diameter of the first lens, and D _L2 is the effective diameter of the second lens. The object side surface of the first lens has a concave surface near the optical axis, and the farther the concave surface is away from the optical axis, the weaker the refractive power of the concave surface.

The third lens may further include a convex surface facing the object side.

The object side of the first lens includes two inflection points.

The Abbe Number of the first lens and the third lens is greater than the Abbe Number of the second lens.

The wide-angle lens satisfies the following condition: 1.48 mm < TLT < 1.50 mm; wherein, the TLT is the sum of the thicknesses of all the refractive lenses on the optical axis in the wide-angle lens.

Wherein the wide-angle lens satisfies the following _{condition: Vd 1> 40, Vd 2} <40, Vd 3>40; wherein, Vd ₁ is the Abbe number of the first lens (Abbe Number), Vd ₂ is the Abbe number of the second lens (an Abbe Number), Vd ₃ is the Abbe Number of the third lens.

Wherein the first lens, the second lens and the third lens satisfy the following condition: -3<f/f ₂ +f/f ₃ -f/f ₁ <7; wherein f is an effective focal length of the wide-angle lens, and f ₁ is the first The effective focal length of the lens, f ₂ is the effective focal length of the second lens, and f ₃ is the effective focal length of the third lens.

Wherein the second lens and the third lens satisfy the following condition: 2<Vd ₃ -Vd ₂ <74; wherein Vd ₂ is an Abbe Number of the second lens, and Vd ₃ is an Abbe number of the third lens ( Abbe Number).

The third lens is made of a glass material.

The first lens and the second lens are made of a plastic material.

Wherein the first lens has at least one aspheric surface or both surfaces are aspheric The surface of the surface of the second lens is at least one aspherical surface or both surfaces are aspherical surfaces, and the third lens has at least one aspherical surface or both surfaces are aspherical surfaces.

The above described objects, features, and advantages of the invention will be apparent from the description and appended claims

1, 2‧‧‧ wide-angle lens

L11, L21‧‧‧ first lens

L12, L22‧‧‧ second lens

L13, L23‧‧‧ third lens

ST1, ST2‧‧ ‧ aperture

OF1, OF2‧‧‧ Filters

IMA1, IMA2‧‧‧ imaging surface

OA1, OA2‧‧‧ optical axis

S11, S12, S13, S14, S15, S16, S17‧‧

S18, S19‧‧‧

S21, S22, S23, S24, S25, S26, S27‧‧

S28, S29‧‧‧

1 is a schematic view showing a lens configuration and an optical path of a first embodiment of a wide-angle lens according to the present invention.

Fig. 2A is a field curvature diagram of the wide-angle lens of Fig. 1.

Figure 2B is a distortion diagram of the wide-angle lens of Figure 1.

Fig. 2C is a diagram of the modulation conversion function of the wide-angle lens of Fig. 1.

Fig. 3 is a view showing a lens configuration and an optical path of a second embodiment of the wide-angle lens according to the present invention.

Figure 4A is a field curvature diagram of the wide-angle lens of Figure 3.

Figure 4B is a distortion diagram of the wide-angle lens of Figure 3.

Fig. 4C is a diagram of the modulation conversion function of the wide-angle lens of Fig. 3.

Please refer to FIG. 1. FIG. 1 is a schematic diagram showing a lens configuration and an optical path of a first embodiment of a wide-angle lens according to the present invention. The wide-angle lens 1 sequentially includes a first lens L11, a second lens L12, an aperture ST1, a third lens L13, and a filter OF1 from the object side to the image side along the optical axis OA1. At the time of imaging, the light from the object side is finally imaged on an image plane IMA1. The first lens L11 has a negative refractive power made of a plastic material, and the object side surface S11 is a concave image side surface S12. For the concave surface, the object side surface S11 and the image side surface S12 are both aspherical surfaces and the object side surface S11 has two inflection points. The second lens L12 has a positive refractive power made of a plastic material, and the object side surface S13 has a convex image side surface S14 which is a concave surface, and the object side surface S13 and the image side surface S14 are aspherical surfaces. The third lens L13 has a positive refractive power made of a glass material, and the object side surface S16 has a convex image side surface S17 which is a convex surface, and the object side surface S16 and the image side surface S17 are both aspherical surfaces. Both the object side surface S18 and the image side surface S19 of the filter OF1 are flat. In the first embodiment, the Abbe coefficients of the first lens L11 and the third lens L13 are larger than the Abbe's coefficient of the second lens L12.

In addition, in order to maintain good optical performance of the wide-angle lens of the present invention, the wide-angle lens 1 of the first embodiment is required to satisfy the following seven conditions: 2.9 < D1 _L11 / D1 _L12 < 3.1 (1)

1.48mm<TLT1<1.50mm (2)

Vd1 ₁ >40 (3)

Vd1 ₂ <40 (4)

Vd1 ₃ >40 (5)

-3<f1/f1 ₂ +f1/f1 ₃ -f1/f1 ₁ <7 (6)

2<Vd1 ₃ -Vd1 ₂ <74 (7)

Wherein D1 _L11 is the effective diameter of the first lens L11, D1 _L12 is the effective diameter of the second lens L12, and the effective diameter D1 _L11 of the first lens L11 is from the edge of the first lens L11 through the first lens L11. straight length to the other edge of the center point, the effective diameter of the second lens L12 _L12 Dl is measured from an edge of the second lens L12 of the second lens L12 passing through the center to the other edge of straight length, wide angle lens 1 is TLT-I The sum of the thicknesses of all the refractive lenses on the optical axis OA1, Vd1 ₁ is the Abbe Number of the first lens L11, and Vd1 ₂ is the Abbe Number of the second lens L12, and Vd1 ₃ is Abbe Number of the third lens L13, f1 is the effective focal length of the wide-angle lens 1, f1 ₁ is the effective focal length of the first lens L11, f1 ₂ is the effective focal length of the second lens L12, and f1 ₃ is the third lens L13 Effective focal length.

By adopting the above-mentioned design of the lens and the aperture ST1, the wide-angle lens 1 can effectively shorten the total length of the lens, increase the viewing angle, effectively correct the aberration, and satisfy the lens resolution when the temperature reaches 60 degrees Celsius.

Table 1 is the relevant parameter table of each lens of the wide-angle lens 1 in Fig. 1. Table 1 shows that the effective focal length of the wide-angle lens 1 of the first embodiment is equal to 0.8074 mm, the aperture value is equal to 2.2, the total length of the lens is equal to 3.26 mm, and the viewing angle is equal to 120. °, the effective diameter of the first lens L11 is equal to 1.53 mm, the effective diameter of the second lens L12 is equal to 0.52 mm, the working environment temperature is equal to 60 degrees Celsius, and the distance between the subject 1 and the wide-angle lens 1 is equal to 2000 mm.

The aspherical surface depression z of each lens in Table 1 is obtained by the following formula: z = ch ² /{1 + [1 - (k + 1) c ² h ² ] ^1/2 } + Ah ⁴ + Bh ⁶ + Ch ⁸ +Dh ¹⁰ +Eh ¹² +Fh ¹⁴ +Gh ¹⁶

Where: c: curvature; h: vertical distance from any point on the lens surface to the optical axis; k: conic coefficient; A~G: aspheric coefficient.

Table 2 is a table of related parameters of the aspherical surface of each lens in Table 1, where k is a conical coefficient (Conic Constant) and A~G is an aspherical coefficient.

In the wide-angle lens 1 of the first embodiment, the effective diameter D1 _{L11 of} the first lens L11 is 1.53 mm, the effective diameter D1 _{L12 of the} second lens L12 is 0.52 mm, and the thickness of all the lenses having the refractive power on the optical axis OA1 in the wide-angle lens 1 The sum of TLT1 = 1.488 mm, the Abbe Number of the first lens L11 Vd1 ₁ = 55.71, the Abbe Number of the second lens L12 Vd1 ₂ = 23.9, and the Abbe's coefficient of the third lens L13 ( Abbe Number) Vd1 ₃ = 57.54, the effective focal length of the wide-angle lens 1 is f1=0.8074 mm, the effective focal length of the first lens L11 is f1 ₁ =-1.0781 mm, and the effective focal length of the second lens L12 is f1 ₂ =1.9537 mm, and the third lens L13 The effective focal length f1 ₃ =0.889495mm, from the above data, D1 _L11 /D1 _L12 = 2.94, TLT1 = 1.488mm, Vd1 ₁ = 55.71, Vd1 ₂ = 23.9, Vd1 ₃ = 57.54, f1/f1 ₂ + f1/f1 ₃ -f1/f1 ₁ =2.0698, Vd1 ₃ -Vd1 ₂ =33.64 can satisfy the requirements of the above conditions (1) to (7).

In addition, the optical performance of the wide-angle lens 1 of the first embodiment can also be achieved, which can be seen from the 2A to 2C drawings. Fig. 2A is a field curvature diagram of the wide-angle lens 1 of the first embodiment. Figure 2B shows the wide-angle lens 1 of the first embodiment. Distortion chart. 2C is a modulation transfer function diagram of the wide-angle lens 1 of the first embodiment.

As can be seen from FIG. 2A, the wide-angle lens 1 of the first embodiment has a field angle of about -0.05 mm in the direction of the Tangential and the Sagittal direction for the light having a wavelength of 0.471 μm, 0.555 μm, and 0.650 μm. Between 0.07mm. From Fig. 2B (the three lines in the figure are almost coincident, so that there seems to be only one line), it can be seen that the wide-angle lens 1 of the first embodiment is different for the distortion of the light having a wavelength of 0.471 μm, 0.555 μm, and 0.650 μm. Between -23% and 0%. As can be seen from FIG. 2C, the wide-angle lens 1 of the first embodiment has a wavelength range of 0.471 μm to 0.650 μm in the direction of the Tangential direction and the Sagittal direction, respectively, and the field of view angle is 0.000 degrees. 12.00 degrees, 24.00 degrees, 42.00 degrees, 60.00 degrees, the spatial frequency is between 0 lp/mm and 83 lp/mm, and the modulation conversion function value is between 0.51 and 1.0. It can be seen that the field curvature and distortion of the wide-angle lens 1 of the first embodiment can be effectively corrected. When the working environment temperature is equal to 60 degrees Celsius, the lens resolution can also meet the requirements, thereby obtaining better optical performance.

Please refer to FIG. 3, which is a schematic diagram of a lens configuration and an optical path of a second embodiment of the wide-angle lens according to the present invention. The wide-angle lens 2 includes a first lens L21, a second lens L22, an aperture ST2, a third lens L23, and a filter OF2 in this order from the object side to the image side along the optical axis OA2. At the time of imaging, the light from the object side is finally imaged on an image plane IMA2. The first lens L21 has a negative refractive power made of a plastic material, and the object side surface S21 has a concave image side surface S22 which is a concave surface, and the object side surface S21 and the image side surface S22 are both aspherical surfaces and the object side surface S21 has two inflection points. The second lens L22 has a positive refractive power made of a plastic material, and the object side surface S23 has a convex image side surface S24 which is a concave surface, and the object side surface S23 and the image side surface S24 are aspherical surfaces. The third lens L23 has a positive refractive power made of a glass material, and the object side surface S26 is convex on the convex image side surface S27. The object side surface S26 and the image side surface S27 are both aspherical surfaces. Both the object side surface S28 and the image side surface S29 of the filter OF2 are flat. In the second embodiment, the Abbe coefficients of the first lens L21 and the third lens L23 are larger than the Abbe's coefficient of the second lens L22.

In addition, in order to maintain good optical performance of the wide-angle lens of the present invention, the wide-angle lens 2 of the second embodiment is required to satisfy the following seven conditions: 2.9 < D2 _L21 / D2 _L22 < 3.1 (8)

1.48mm<TLT2<1.50mm (9)

Vd2 ₁ >40 (10)

Vd2 ₂ <40 (11)

Vd2 ₃ >40 (12)

-3<f2/f2 ₂ +f2/f2 ₃ -f2/f2 ₁ <7 (13)

2<Vd2 ₃ -Vd2 ₂ <74 (14)

Wherein, D2 _L21 is the effective diameter of the first lens L21, D2 _L22 is the effective diameter of the second lens L22, and the effective diameter D2 _L21 of the first lens L21 is from the edge of the first lens L21 through the first lens L21. The length of the straight line from the center point to the other edge, the effective diameter D2 _L22 of the second lens L22 refers to the length of the line from one edge of the second lens L22 through the center point of the second lens L22 to the other edge, and the TLT 2 is the wide-angle lens 2 The sum of the thicknesses of all the refractive lenses on the optical axis OA2, Vd2 ₁ is the Abbe Number of the first lens L21, and Vd2 ₂ is the Abbe Number of the second lens L22, and Vd2 ₃ is Abbe Number of the third lens L23, f2 is the effective focal length of the wide-angle lens 2, f2 ₁ is the effective focal length of the first lens L21, f2 ₂ is the effective focal length of the second lens L22, and f2 ₃ is the third lens L23 Effective focal length.

With the design of the above lens and aperture ST2, the wide-angle lens 2 can be Effectively shorten the total length of the lens, increase the viewing angle, effectively correct the aberration, and the lens resolution can meet the requirements when the shooting distance is 300mm.

Table 3 is a table of related parameters of the lenses of the wide-angle lens 2 in FIG. 3, and Table 3 shows that the effective focal length of the wide-angle lens 2 of the second embodiment is equal to 0.7067 mm, the aperture value is equal to 2.2, the total length of the lens is equal to 3.27 mm, and the viewing angle is equal to 120. °, the effective diameter of the first lens L21 is equal to 1.5 mm, the effective diameter of the second lens L22 is equal to 0.49 mm, the working ambient temperature is equal to 40 degrees Celsius, and the distance between the subject 2 and the wide-angle lens 2 is equal to 300 mm.

The aspherical surface depression z of each lens in Table 3 is obtained by the following formula: z = ch ² /{1 + [1 - (k + 1) c ² h ² ] ^1/2 } + Ah ⁴ + Bh ⁶ + Ch ⁸ +Dh ¹⁰ +Eh ¹² +Fh ¹⁴ +Gh ¹⁶

Where: c: curvature; h: vertical distance from any point on the lens surface to the optical axis; k: conic coefficient; A~G: aspheric coefficient.

Table 4 is the relevant parameter table of the aspherical surface of each lens in Table 3, where k is the conical coefficient (Conic Constant) and A~G is the aspherical coefficient.

In the wide-angle lens 2 of the second embodiment, the effective diameter D2 _{L21 of} the first lens L21 is 1.5 mm, the effective diameter D2 _{L22 of the} second lens L22 is 0.49 mm, and the thickness of all the lenses having the refractive power on the optical axis OA2 in the wide-angle lens 2 The sum of TLT2 = 1.491 mm, the Abbe Number of the first lens L21 Vd2 ₁ = 55.71, the Abbe Number of the second lens L22 Vd2 ₂ = 23.9, and the Abbe's coefficient of the third lens L23 ( Abbe Number) Vd2 ₃ = 80, the effective focal length f2 of the wide-angle lens 2 is 0.7067 mm, the effective focal length of the first lens L21 is f2 ₁ = -1.2239 mm, and the effective focal length of the second lens L22 is f2 ₂ = 1.9537 mm, and the third lens L23 The effective focal length f2 ₃ =0.8384mm, from the above data, D2 _L21 /D2 _L22 =3.06, TLT2=1.491mm, Vd2 ₁ =55.71, Vd2 ₂ =23.9, Vd2 ₃ =80, f2/f2 ₂ +f2/f2 ₃ -f2/f2 ₁ = 1.782, Vd2 _{3 -} Vd2 ₂ = 56.1 can satisfy the requirements of the above conditions (8) to (14).

In addition, the optical performance of the wide-angle lens 2 of the second embodiment can also be achieved, which can be seen from Figs. 4A to 4C. Fig. 4A is a field curvature diagram of the wide-angle lens 2 of the second embodiment. Fig. 4B is a distortion diagram of the wide-angle lens 2 of the second embodiment. Fig. 4C is a modulation transfer function diagram of the wide-angle lens 2 of the second embodiment.

As can be seen from FIG. 4A, the wide-angle lens 2 of the second embodiment has a wavelength of 0.471. The tangential direction and the sagittal direction field curvature produced by the light of μm, 0.555 μm, and 0.650 μm are between -0.04 mm and 0.07 mm. From Fig. 4B (the three lines in the figure are almost coincident, so that it seems that there is only one line), it can be seen that the wide-angle lens 2 of the second embodiment is different for the distortion of the light having a wavelength of 0.471 μm, 0.555 μm, and 0.650 μm. Between -24.5% and 0%. As can be seen from FIG. 4C, the wide-angle lens 2 of the second embodiment has a wavelength range of 0.471 μm to 0.650 μm in the direction of the Tangential direction and the Sagittal direction, respectively, and the field of view angle is 0.000 degrees. 12.00 degrees, 24.00 degrees, 42.00 degrees, 60.00 degrees, the spatial frequency is between 0 lp/mm and 83 lp/mm, and the modulation conversion function value is between 0.6 and 1.0. It can be seen that the field curvature and distortion of the wide-angle lens 2 of the second embodiment can be effectively corrected. When the distance between the subject 2 and the wide-angle lens 2 is equal to 300 mm, the lens resolution can also satisfy the requirements, thereby obtaining better optical performance.

1‧‧‧ wide-angle lens

L11‧‧‧ first lens

L12‧‧‧ second lens

L13‧‧‧ third lens

ST1‧‧‧ aperture

OF1‧‧‧Filter

OA1‧‧‧ optical axis

IMA1‧‧‧ imaging surface

S11, S12, S13, S14, S15‧‧

S16, S17, S18, S19‧‧‧

Claims (11)

A wide-angle lens includes, in order from the object side to the image side along the optical axis, a first lens, the first lens is a biconcave lens having a negative refractive power, and a second lens having a positive refractive power, the second lens having a positive refractive power. a convex surface of the second lens facing the object side concave surface toward the image side; an aperture; and a third lens having a positive refractive power and including a convex surface facing the image side; wherein the wide-angle lens satisfies the following condition: 2.9<D _L1 / D _L2 <3.1 wherein D _{L1 is} the effective diameter of the first lens, and D _{L2 is} the effective diameter of the second lens; wherein the object side of the first lens has a concave surface near the optical axis, the concave surface The farther away from the optical axis, the weaker the refractive power of the concave surface. The wide-angle lens of claim 1, wherein the third lens further comprises a convex surface facing the object side. The wide-angle lens of claim 1, wherein the object side of the first lens comprises two inflection points. The wide-angle lens of claim 1, wherein an Abbe Number of the first lens and the third lens is greater than an Abbe Number of the second lens. The wide-angle lens according to claim 1, wherein the wide-angle lens satisfies the following condition: 1.48 mm<TLT<1.50 mm Wherein, the TLT is the sum of the thicknesses of all the refractive lenses on the optical axis in the wide-angle lens. The wide-angle lens according to claim 1, wherein the wide-angle lens satisfies the following condition: Vd ₁ >40 Vd ₂ <40 Vd ₃ >40, wherein Vd _{1 is an} Abbe Number of the first lens, Vd _{2 is an} Abbe Number of the second lens, and Vd _{3 is an} Abbe Number of the third lens. The wide-angle lens of claim 1, wherein the first lens, the second lens, and the third lens satisfy the following condition: -3<f/f ₂ +f/f ₃ -f/f ₁ <7 Where f is the effective focal length of the wide-angle lens, f _{1 is} the effective focal length of the first lens, f _{2 is} the effective focal length of the second lens, and f _{3 is} the effective focal length of the third lens. The wide-angle lens of claim 1, wherein the second lens and the third lens satisfy the following condition: 2 < Vd ₃ - Vd ₂ < 74, wherein Vd ₂ is an Abbe coefficient of the second lens (Abbe Number), Vd _{3 is} the Abbe Number of the third lens. The wide-angle lens of claim 1, wherein the third lens is made of a glass material. The wide-angle lens of claim 1, wherein the first lens and the second lens are made of a plastic material. The wide-angle lens of claim 1, wherein the first lens has at least one aspherical surface or both surfaces are aspherical surfaces, and the second lens has at least one aspheric surface or both surfaces. For the aspherical surface, the third lens has at least one aspheric surface or both surfaces are aspherical surfaces.