CN112051660A

CN112051660A - Periscopic lens

Info

Publication number: CN112051660A
Application number: CN202011043321.1A
Authority: CN
Inventors: 王哲; 金兑映; 宋亮
Original assignee: Liaoning Zhonglan Photoelectric Technology Co Ltd
Current assignee: Liaoning Zhonglan Photoelectric Technology Co Ltd
Priority date: 2020-09-28
Filing date: 2020-09-28
Publication date: 2020-12-08

Abstract

The invention relates to a periscopic lens, which comprises the following components in sequence from an object side to an image side along an optical axis: a first lens element having a positive refractive power, and an object-side surface and an image-side surface both being convex at a paraxial region; a second lens having negative refractive power and a concave image-side surface; a third lens having refractive power and a convex object-side surface; a fourth lens having negative refractive power; the first lens, the second lens, the third lens and the fourth lens are all aspheric plastic lenses, the diaphragm is arranged between the second lens and the third lens, and the lenses on two sides of the diaphragm have different refractive powers. The invention satisfies the characteristics of periscope and long focus, has the characteristics of high illumination and clear imaging, realizes the miniaturization of the lens, is matched with the prism when in use, and has wide application range.

Description

Periscopic lens

Technical Field

The invention relates to an optical system, in particular to a periscopic lens.

Background

With the development of mobile phone camera shooting technology, the shooting function of mobile phones is gradually enriched, and optical lenses with different functions, such as a front-shooting small-head lens, a telescopic lens, a zoom lens, a wide-angle lens and the like, are gradually emerged. However, in response to market demands, the volume of the mobile phone is being reduced and the weight thereof is being reduced, so that the camera lens adopted in the mobile phone has to be improved adaptively.

Along with the lighter and thinner of cell-phone, several first lenses in the periscope camera lens in the past are thicker, and the camera lens needs increase lens cone thickness to the structural strength who adapts to the camera lens to influence the size of periscope, can't adapt to the frivolous design of cell-phone. The illumination of the lens is affected by using a lens with a small aperture, so that the use of the periscopic lens in the mobile phone lens is limited.

Disclosure of Invention

The invention aims to provide a periscopic lens which is reasonable in configuration and reliable in use, meets the characteristics of periscopic and telephoto, has the characteristics of high illumination and clear imaging, realizes miniaturization of the lens, is matched with a prism when in use, and has a wide application range.

The technical scheme of the invention is as follows:

a periscopic lens is provided, which comprises the following components in order from an object side to an image side along an optical axis: a first lens element having a positive refractive power, and an object-side surface and an image-side surface both being convex at a paraxial region; a second lens having negative refractive power and a concave image-side surface; a third lens having refractive power and a convex object-side surface; a fourth lens having negative refractive power; first lens, second lens, third lens and fourth lens all adopt aspheric surface plastic lens, and the diaphragm setting is between second lens and third lens and the lens of diaphragm both sides have different refractive power, the camera lens still satisfies following conditional expression:

0.15<CT2/CT3<0.8

0.1<CT12/TTL<0.2

wherein CT2 is the central thickness of the second lens element, CT3 is the central thickness of the third lens element, CT12 is the distance from the object-side surface of the first lens element to the image-side surface of the second lens element on the optical axis, and TTL is the total optical length of the lens assembly.

The periscopic lens further satisfies the following conditional expressions:

-0.9<(R1+R2)/(R1-R2)<-0.5

wherein, R1 is the curvature radius of the object side surface of the first lens, and R2 is the curvature radius of the image side surface of the first lens. After the lens meets the conditions, the influence of distortion on the lens is reduced, and therefore the shooting quality of the lens is improved.

The periscopic lens further satisfies the following conditional expressions:

F1/EFL<0.45

wherein F1 is the focal length of the first lens, and EFl is the effective focal length of the lens. After the lens meets the conditions, the miniaturization of the lens is realized, the shooting quality of the lens is improved, and if the shooting quality of the lens exceeds the limit range of the lens, the miniaturization of the lens cannot be realized if the shooting quality of the lens is met.

The periscopic lens further satisfies the following conditional expressions:

-1≤R4/F2＜0

wherein R4 is the curvature radius of the image side surface of the second lens, and F2 is the effective focal length of the second lens. After the lens meets the conditions, light rays entering the lens can be optimized, and the illumination of the lens is improved.

The periscopic lens further satisfies the following conditional expressions:

-1.1<R8/F4

wherein R8 is the curvature radius of the image side surface of the fourth lens, and F4 is the effective focal length of the fourth lens. After the lens meets the conditions, the influence of astigmatism on the lens can be improved, and therefore the shooting capability of the lens is improved.

The periscopic lens further satisfies the following conditional expressions:

1.0≤EFL/TTL

wherein EFl is the effective focal length of the lens, and TTL is the total optical length of the lens. After the lens meets the conditions, the lens has the telescopic function, and clear pictures can be shot.

The periscopic lens further satisfies the following conditional expressions:

0.8<SD1/HIMA<1.1

0.5<SD8/HIMA<0.8

wherein SD1 is the effective clear aperture of the object side surface of the first lens, SD8 is the effective clear aperture of the image side surface of the fourth lens, and HIMA is the half image height of the lens. When the condition of the lens is lower than the lower limit of the conditional expression requirement, the illuminance of the lens is seriously affected, and when the condition of the lens is higher than the upper limit of the conditional expression requirement, the volume of the lens is increased, so that the miniaturization of the lens is difficult to realize.

The invention has the beneficial effects that:

the size of the lens is reduced through reasonable configuration of the four lenses, including lens combination and distance collocation. Through satisfying the requirement of conditional expression, when realizing reducing the volume, guarantee that the camera lens can shoot clear image, promote the imaging quality of camera lens. The plastic lens is adopted to replace the glass lens, so that the weight of the lens is reduced on the premise of not influencing the shooting quality. The periscopic mode ensures that the lens has the telescopic function and simultaneously ensures the miniaturization of the lens. The optical system also has the characteristic of high illumination. When in use, the prism is matched, the assembly is simple, and the application range is wide.

Drawings

Fig. 1 is a schematic structural diagram of a lens barrel according to embodiment 1 of the present invention;

FIG. 2A is a distortion curve of a lens according to embodiment 1 of the present invention;

fig. 2B is an astigmatism curve of the lens according to embodiment 1 of the present invention;

fig. 2C is an illuminance curve of the lens according to embodiment 1 of the present invention;

fig. 3 is a schematic structural diagram of a lens barrel according to embodiment 2 of the present invention;

FIG. 4A is a distortion curve of the lens of embodiment 2 of the present invention;

fig. 4B is an astigmatism curve of the lens according to embodiment 2 of the present invention;

fig. 4C is an illuminance curve of the lens according to embodiment 2 of the present invention;

fig. 5 is a schematic structural diagram of a lens barrel according to embodiment 3 of the present invention;

FIG. 6A is a distortion curve of the lens according to embodiment 3 of the present invention;

fig. 6B is an astigmatism curve of the lens according to embodiment 3 of the present invention;

fig. 6C is an illuminance curve of the lens according to embodiment 3 of the present invention;

fig. 7 is a schematic structural diagram of a lens barrel according to embodiment 4 of the present invention;

FIG. 8A is a distortion curve of the lens of embodiment 4 of the present invention;

fig. 8B is an astigmatism curve of the lens according to embodiment 4 of the present invention;

fig. 8C is an illuminance curve of the lens according to embodiment 4 of the present invention.

In the figure: p1, a first lens, p2, a second lens, p3, a third lens, p4, a fourth lens, a stop, an IR-cut filter, an ima, an imaging surface;

1. the lens comprises a first lens, an object side surface, a second lens, an image side surface, a third lens, an object side surface, a fourth lens, an image side surface, a fourth lens, a fifth lens, a sixth lens, a seventh lens, a sixth.

Detailed Description

Example 1

As shown in fig. 1, the periscopic lens includes, in order from an object side to an image side along an optical axis: a first lens element having a positive refractive power, and an object-side surface and an image-side surface both being convex at a paraxial region; a second lens having negative refractive power, both the object-side surface and the image-side surface being concave; a third lens element having positive refractive power, a convex object-side surface and a concave image-side surface; and the fourth lens has negative refractive power, and the object side surface of the fourth lens is a convex surface while the image side surface of the fourth lens is a concave surface. The first lens, the second lens, the third lens and the fourth lens are all aspheric plastic lenses, and the diaphragm is arranged between the second lens and the third lens. The incident light sequentially passes through the surfaces of the lenses and the optical filter and is finally imaged on an imaging surface.

The periscopic lens simultaneously satisfies the following conditional expressions:

0.15<CT2/CT3<0.8

0.1<CT12/TTL<0.2

-0.9<(R1+R2)/(R1-R2)<-0.5

F1/EFL<0.45

-1≤R4/F2＜0

-1.1<R8/F4

1.0≤EFL/TTL

0.8<SD1/HIMA<1.1

0.5<SD8/HIMA<0.8

CT2 is the central thickness of the second lens (in mm), CT3 is the central thickness of the third lens, CT12 is the distance (in mm) from the object-side surface of the first lens to the image-side surface of the second lens on the optical axis, TTL is the total optical length (in mm) of the lens, R1 is the radius of curvature of the object-side surface of the first lens (in mm), R2 is the radius of curvature of the image-side surface of the first lens, R4 is the radius of curvature of the image-side surface of the second lens, R8 is the radius of curvature of the image-side surface of the fourth lens, EFl is the effective focal length (in mm) of the lens, F1 is the focal length of the first lens, F2 is the effective focal length of the second lens, F4 is the effective focal length of the fourth lens, SD1 is the effective clear aperture (in mm) of the object-side surface of the first lens, SD8 is the effective clear aperture of the image-side surface of the fourth lens, and HIMA is the half-height (in mm) of the lens.

The periscopic lens comprises a first lens, a second lens, a third lens and a fourth lens, wherein the object side surface and the image side surface of the first lens, the second lens, the third lens and the fourth lens are aspheric surfaces, and aspheric coefficients meet the following equation:

Z＝cy²/[1+{1－(1+k)c² y²}^+1/2]+A₄y⁴+A₆y⁶+A₈y⁸+A₁₀y¹⁰+A₁₂y¹²+A₁₄y¹⁴+A₁₆y¹⁶

wherein Z is aspheric sagittal height, c is aspheric paraxial curvature, y is lens caliber, k is cone coefficient, A₄Is a 4-order aspheric coefficient, A₆Is a 6-degree aspheric surface coefficient, A₈Is an 8 th order aspheric surface coefficient, A₁₀Is a 10 th order aspheric surface coefficient, A₁₂Is a 12 th order aspheric surface coefficient, A₁₄Is a 14 th order aspheric coefficient, A₁₆Is a 16-degree aspheric coefficient.

In this embodiment, the lens set design parameters refer to the following table:

table one (a) shows the surface type, radius of curvature, thickness and material of each lens of the lens barrel described in example 1. Wherein the unit of the radius of curvature and the thickness are both millimeters (mm).

Watch 1 (a)

Table one (b) shows the aspherical coefficients of the respective lenses.

Watch 1 (b)

In this embodiment, the lens meets the requirements of the conditional expressions, and the specific parameters are shown in table one (c):

watch 1 (c)

According to the table one (a), the table one (b) and fig. 1, the shape of the lens and the thickness of the material of the lens of the current embodiment are clearly shown, and the current embodiment realizes the periscope with small volume by adjusting the shape of the lens, the position of the lens and the material of the lens. And the light rays passing through the lens are converged on the image surface, which shows that the lens has good capability of shooting images.

According to the clear demonstration of the illumination conditions in table one (c) and fig. 2A, after the lens meets the requirements of the claims, the distortion of the lens is less than 1%, which indicates that the lens can effectively reduce the influence of the distortion on the lens shooting and realize the capability of the lens for clearly shooting images.

As shown clearly in table (c) and the distortion curve in fig. 2B, after the lens meets the requirements of the claims, the lens can effectively reduce the influence caused by astigmatism, and effectively improve the shooting capability of the lens.

According to the clear demonstration of the astigmatism curves in table i (C) and fig. 2C, the illuminance of the marginal field ray on the image plane reaches 90%, which indicates that the lens has less illuminance loss when passing through the lens, and the shot image is brighter.

It is explained from the above information that the embodiment of the periscope has the characteristics of miniaturization of the lens, high illumination of the lens, and taking of a clear image.

Example 2

As shown in fig. 3, the periscopic lens includes, in order from an object side to an image side along an optical axis: a first lens element having a positive refractive power, and an object-side surface and an image-side surface both being convex at a paraxial region; a second lens having negative refractive power, both the object-side surface and the image-side surface being concave; a third lens element having positive refractive power, a convex object-side surface and a concave image-side surface; and the fourth lens has negative refractive power, and both the object side surface and the image side surface are concave. The first lens, the second lens, the third lens and the fourth lens are all aspheric plastic lenses, and the diaphragm is arranged between the second lens and the third lens. The incident light sequentially passes through the surfaces of the lenses and the optical filter and is finally imaged on an imaging surface.

The design parameters of the lens assembly of the present embodiment refer to the following table: table two (a) shows the surface type, radius of curvature, thickness, and material of each lens of the optical lens of example 2.

Watch two (a)

Lens	Surface number	Surface type	Radius of curvature	Thickness of	Material Property (Nd: Vd)
							OBJ	Spherical surface	INF	INF
P1
		1	Aspherical surface	3.072	1.09	1.5445：55.99
							2	Aspherical surface	-27.012	0.17
	P2	3	Aspherical surface	-10.543	0.33	1.6397：23.53
							4	Aspherical surface	5.613	0.70
	Diaphragm	Stop	Spherical surface	INF	-0.24
P3							5	Aspherical surface	4.469	1.48	1.6397：23.53
		6	Aspherical surface	9.637	1.21
P4							7	Aspherical surface	-21.176	1.29	1.5352：56.12
		8	Aspherical surface	11.266	0.58
BK7							13	Spherical surface	INF	0.21	BK7_SCHOTT
		14	Spherical surface	INF	4.10
IMA

Watch two (b)

In this embodiment, the lens meets the requirements of the conditional expressions, and the specific parameters are shown in the following table:

watch two (c)

According to the second table (a), the second table (b) and fig. 3, the shape of the lens and the thickness of the material of the lens in the current embodiment are clearly shown, and the current embodiment realizes the periscope with small volume by adjusting the shape of the lens, the position of the lens and the material of the lens. And the light rays passing through the lens are converged on the image surface, which shows that the lens has good capability of shooting images.

According to the clear demonstration of the illumination conditions in table two (c) and fig. 4A, after the lens meets the requirements of the claims, the distortion of the lens is less than 0.5%, which indicates that the lens can effectively reduce the influence of the distortion on the lens shooting, and the ability of the lens to clearly shoot images is realized.

As shown clearly in table two (c) and the distortion curve in fig. 4B, after the lens meets the requirements of the claims, the lens can effectively reduce the influence caused by astigmatism, and effectively improve the shooting capability of the lens.

It is clearly shown in table two (C) and fig. 4C that the illuminance of the peripheral field ray on the image plane reaches 73%, which indicates that the lens has less illuminance loss when passing through the lens, and the shot image is brighter.

Example 3

As shown in fig. 5, the periscopic lens includes, in order from an object side to an image side along an optical axis: a first lens element having a positive refractive power, and an object-side surface and an image-side surface both being convex at a paraxial region; a second lens having negative refractive power, both the object-side surface and the image-side surface being concave; a third lens element having positive refractive power, a convex object-side surface and a concave image-side surface; and the fourth lens has negative refractive power, and both the object side surface and the image side surface are concave. The first lens, the second lens, the third lens and the fourth lens are all aspheric plastic lenses, and the diaphragm is arranged between the second lens and the third lens. The incident light sequentially passes through the surfaces of the lenses and the optical filter and is finally imaged on an imaging surface.

The design parameters of the lens assembly of the present embodiment refer to the following table: table three (a) shows the surface type, radius of curvature, thickness, and material of each lens of the optical lens of example 3.

Watch III (a)

Lens	Surface number	Surface type	Radius of curvature	Thickness of	Material Property (Nd: Vd)
							OBJ	Spherical surface	INF	INF
P1
		1	Aspherical surface	2.996	1.49	544500.5599
							2	Aspherical surface	-14.004	0.10
	P2	3	Aspherical surface	-10.142	0.30	639700.2353
							4	Aspherical surface	4.409	0.95
	Diaphragm	Stop	Spherical surface	INF	-0.31
P3							5	Aspherical surface	5.780	0.50	661200.2035
		6	Aspherical surface	26.728	2.10
P4							7	Aspherical surface	-13.166	1.30	535200.5612
		8	Aspherical surface	10.695	0.58
BK7							13	Spherical surface	INF	0.21	BK7_SCHOTT
		14	Spherical surface	INF	3.67
IMA

Watch III (b)

watch III (c)

According to the third table (a), the third table (b) and fig. 5, the shape of the lens and the thickness of the material of the lens of the current embodiment are clearly shown, and the current embodiment realizes the periscope lens with small volume by adjusting the shape of the lens, the position of the lens and the material of the lens. And the light rays passing through the lens are converged on the image surface, which shows that the lens has good capability of shooting images.

According to the third table (c) and the clear display of the illumination condition in fig. 6A, after the lens meets the requirement of the claim item, the distortion of the lens is less than 1%, which shows that the lens can effectively reduce the influence of the distortion on the lens shooting and realize the clear image shooting capability of the lens.

According to the conditions of the distortion curves in table three (c) and fig. 6B, it is clearly shown that after the lens meets the requirements of the claims, the lens can effectively reduce the influence caused by astigmatism, and effectively improve the shooting capability of the lens.

According to the conditions of the astigmatism curves in the third table (C) and fig. 6C, it is clearly shown that the illuminance of the marginal field ray on the image plane reaches 90%, which indicates that the lens has less illuminance loss when passing through the lens, and the shot image is brighter.

Example 4

As shown in fig. 7, the periscopic lens includes, in order from an object side to an image side along an optical axis: a first lens element having a positive refractive power, and an object-side surface and an image-side surface both being convex at a paraxial region; a second lens element having negative refractive power, the object-side surface being convex and the image-side surface being concave; the third lens has positive refractive power, and both the object side surface and the image side surface are convex surfaces; and the fourth lens has negative refractive power, and the object side surface of the fourth lens is a convex surface while the image side surface of the fourth lens is a concave surface. The first lens, the second lens, the third lens and the fourth lens are all aspheric plastic lenses, and the diaphragm is arranged between the second lens and the third lens. The incident light sequentially passes through the surfaces of the lenses and the optical filter and is finally imaged on an imaging surface.

The design parameters of the lens assembly of the present embodiment refer to the following table:

table four (a) shows the surface type, radius of curvature, thickness, and material of each lens of the optical lens of example 4.

Watch four (a)

Lens	Surface number	Surface type	Radius of curvature	Thickness of	Material Property (Nd: Vd)
							OBJ	Spherical surface	INF	INF
P1
		1	Aspherical surface	2.798	1.17	1.5445：55.99
							2	Aspherical surface	-39.389	0.53
	P2	3	Aspherical surface	67.638	0.33	1.6397：23.53
							4	Aspherical surface	2.792	0.60
	Diaphragm	Stop	Spherical surface	INF	-0.03
P3							5	Aspherical surface	10.084	1.98	1.6397：23.53
		6	Aspherical surface	-18.122	0.65
P4							7	Aspherical surface	6.568	1.09	1.5352.56.12
		8	Aspherical surface	10.777	0.68
BK7							13	Spherical surface	INF	0.21	BK7_SCHOTT
		14	Spherical surface	INF	3.99
IMA

Watch four (b)

watch four (c)

According to the fourth table (a), the fourth table (b) and fig. 7, the shape of the lens and the thickness of the material of the lens of the current embodiment are clearly shown, and the current embodiment realizes a periscope lens with a small volume by adjusting the shape of the lens, the position of the lens and the material of the lens. And the light rays passing through the lens are converged on the image surface, which shows that the lens has good capability of shooting images.

According to the clear demonstration of the illumination conditions in table four (c) and fig. 8A, after the lens meets the requirements of the claims, the distortion of the lens is less than 1%, which indicates that the lens can effectively reduce the influence of the distortion on the lens shooting and realize the capability of the lens for clearly shooting images.

As shown clearly in table four (c) and the distortion curve in fig. 8B, after the lens meets the requirements of the claims, the lens can effectively reduce the influence caused by astigmatism, and effectively improve the shooting capability of the lens.

It is clearly shown from the astigmatism curves in table four (C) and fig. 8C that the illuminance of the marginal field ray on the image plane reaches 75%, which indicates that the lens has less illuminance loss when passing through the lens, and the shot image is brighter.

Claims

1. A periscopic lens, comprising, in order from an object side to an image side along an optical axis: a first lens element having a positive refractive power, and an object-side surface and an image-side surface both being convex at a paraxial region; a second lens having negative refractive power and a concave image-side surface; a third lens having refractive power and a convex object-side surface; a fourth lens having negative refractive power; first lens, second lens, third lens and fourth lens all adopt aspheric surface plastic lens, and the diaphragm setting is between second lens and third lens and the lens of diaphragm both sides have different refractive power, the camera lens still satisfies following conditional expression:

0.15<CT2/CT3<0.8

0.1<CT12/TTL<0.2

2. A periscopic lens according to claim 1, further satisfying the following conditional expressions:

-0.9<(R1+R2)/(R1-R2)<-0.5

wherein, R1 is the curvature radius of the object side surface of the first lens, and R2 is the curvature radius of the image side surface of the first lens.

3. A periscopic lens according to claim 1, further satisfying the following conditional expressions:

F1/EFL<0.45

wherein F1 is the focal length of the first lens, and EFl is the effective focal length of the lens.

4. A periscopic lens according to claim 1, further satisfying the following conditional expressions:

-1≤R4/F2＜0

wherein R4 is the curvature radius of the image side surface of the second lens, and F2 is the effective focal length of the second lens.

5. A periscopic lens according to claim 1, further satisfying the following conditional expressions:

-1.1<R8/F4

wherein R8 is the curvature radius of the image side surface of the fourth lens, and F4 is the effective focal length of the fourth lens.

6. A periscopic lens according to claim 1, further satisfying the following conditional expressions:

1.0≤EFL/TTL

wherein EFl is the effective focal length of the lens, and TTL is the total optical length of the lens.

7. A periscopic lens according to claim 1, further satisfying the following conditional expressions:

0.8<SD1/HIMA<1.1

0.5<SD8/HIMA<0.8

wherein SD1 is the effective clear aperture of the object side surface of the first lens, SD8 is the effective clear aperture of the image side surface of the fourth lens, and HIMA is the half image height of the lens.