CN117916644A

CN117916644A - Zoom lens optical system

Info

Publication number: CN117916644A
Application number: CN202180101047.5A
Authority: CN
Inventors: 宮谷崇太; 佟庆; 安泽卓也; 泉亮太郎; 热田一也
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2021-08-02
Filing date: 2021-08-02
Publication date: 2024-04-19
Also published as: WO2023010239A1

Abstract

There is provided a switching zoom lens, from an object side to an image side along an Optical Axis (OA), comprising: a reflective optical element (P) for bending an optical path from the object side to the image side; a front lens group (Gf) having a positive refractive index; a rear lens group (Gr) comprising three or more and five or less lens elements (L7-L10). The rear lens group (Gr) is interposed between the front lens group (Gf) and an imaging surface (IMG) when zooming from a wide-angle end to a telephoto end, and is moved out of the optical path of the switching zoom lens when zooming from the telephoto end to the wide-angle end.

Description

Zoom lens optical system

Technical Field

The present invention relates to an imaging lens that forms an object image for a solid-state image sensor such as a CCD or CMOS sensor, and more particularly, to a portable device typified by a smart phone, a game machine, a PC, a web camera, a home appliance, an automobile, or an unmanned aerial vehicle. The present invention relates to an imaging lens and an imaging apparatus mounted on a camera or the like.

Background

With the popularization of smart phones in recent years, the demand for imaging lenses has become diversified, and it has been desired to improve optical properties such as wider angle of view, higher tele performance, and larger diameter (NA) while maintaining the imaging module size directly affected by the product size. Nowadays, in view of the fact that a multi-camera system has become mainstream, a wide-angle lens plays an important role in the differentiation of smart phone products because it is often used for still image and moving image photographing of long-distance subjects such as sports events, landscapes, astronomical observations, and the like.

In view of the need to reduce the height of long lens modules, existing smartphones use periscopes with right angle prisms as the optical system for such modules. In most cases today, however, such tele periscopes have a fixed focus and a fixed viewing angle. Therefore, when long-focus shooting is required, digital images are often cropped and up-converted by digital zooming, which causes a problem of degradation in image quality.

The use of a zoom lens system may be considered to solve this problem. However, when a zoom optical system having a lens group (which moves along an optical axis to perform zooming) is used, as the zoom magnification increases, the moving distance of the lens group for zooming becomes longer, which is a major factor that causes an increase in the size and cost of a small lens module of a smart phone or the like. For example, in a periscope type zoom lens, there is a prior art of shifting an optical axis, however, when shifting the optical axis, doubling the magnification leads to a lens shift distance as long as about 6 mm.

In order to solve the above-described problems, the present invention provides an imaging lens capable of optically switching a view angle between a telephoto and a wide angle without changing a total track length (total TRACK LENGTH, TTL).

Disclosure of Invention

The present invention alleviates and/or eliminates the above disadvantages.

It is a primary object of the present invention to provide a lens that has a size mountable on a mobile device and optically switches a viewing angle between a telephoto and a wide-angle without changing TTL.

According to a first aspect, a switched zoom lens is provided. Switching the zoom lens from the object side to the image side along the optical axis includes: a reflective optical element for bending an optical path from the object side to the image side; a front lens group having a positive refractive index; a rear lens group including three or more and five or less lens elements. The rear lens group is interposed between the front lens group and the imaging surface upon zooming from the wide angle end to the telephoto end, and is moved out of the optical path of the switching zoom lens upon zooming from the telephoto end to the wide angle end.

The switching is actuated by a switching mechanism that is powered by a piezoelectric element, VCM, or the like.

Conventional zoom lenses require high precision in all positions on the optical axis from the wide-angle end to the telephoto end, and bifocal zoom lenses require high holding precision in a plurality of positions on the optical axis. Therefore, compared with such a conventional zoom lens and a bifocal zoom lens, the present invention only needs to ensure positional accuracy when the rear lens group Gr is inserted into the optical path, so it can be said that the amount of decrease in optical performance is smaller than that of the conventional lens, and rapid zooming is more easily performed.

Another advantage is that in such a tele state, the holding accuracy of the rear lens group Gr can be achieved by a relatively low-cost method (e.g., an offset mechanism). The switching mechanism may include a mechanism that linearly repeats insertion and removal while maintaining the same posture of the rear lens group Gr, and a pendulum mechanism that actuates an angle of an optical axis of the rear lens group Gr when the rear lens group Gr is inserted and removed.

By using such a switched zoom lens module, high-speed optical magnification variation can be provided while avoiding the use of a mechanism and costly zoom motor to move the lens group for zooming widely.

The switching zoom lens may be configured as a periscope type by bending an optical path from an object using a reflective optical element. The periscope type is advantageous for reducing the height of the lens module. The reflective optical element may be omitted, but since the total length of the tele-type lens module is long, the thickness tends to increase in the direction in which the lens (camera) is directed.

If the number of lens elements of the rear lens group is less than 3, aberration correction power in the tele state is insufficient, and resolution performance is degraded. If the rear lens group has five or more lens elements, the weight and volume of the rear lens group increase, which results in an increase in load upon insertion and removal, which also has a problem that a large space is required for evacuation in the wide-angle state, and the like.

According to one aspect of the present switching zoom lens system, when ft is a focal length of the switching zoom lens in the telephoto state, fw is a focal length of the zoom lens in the wide-angle state, FOVw is a field angle of the switching zoom lens in the wide-angle state, the following condition is satisfied:

(i)1.2≤ft/fw≤3；

(ii)16.5°≤FOVw≤28.5°。

Condition (i) defines a zoom ratio between the wide-angle state and the telephoto state. If the zoom ratio is below the lower limit of the range, it is easier to design the shot, but the zoom ratio is too small to provide the desired user experience. If the zoom ratio exceeds the upper limit of the range, the user will understand a large zoom ratio, but the F-number becomes too large due to the characteristic of an optical system called a periscope type in which the aperture is limited, which results in degradation of resolution performance due to diffraction limitation. Further, when the zoom ratio becomes large, the movement amount of the front lens group required to change the magnification increases. This makes it difficult to solve the problems of keeping the moving distance of the lens group small at the time of zooming, and suppressing the motor size and cost of the present invention.

Alternatively, the following conditions are satisfied:

(i)-2 1.25≤ft/fw≤2.5；

(ii)-2 18.5°≤FOVw≤26.5°。

condition (ii) defines a viewing angle in the wide-angle state. If the angle of view is below the lower limit of the range, the angle of view in the wide-angle state becomes too narrow to be considered wide. In contrast, if the angle of view exceeds the upper limit of the range, the angle of view in the wide-angle state becomes too large to be a periscope type system. In particular, vignetting occurs at the peripheral viewing angle on the reflective optical element.

According to one aspect of the present switching zoom lens system, when X is a zoom ratio of the switching zoom lens (expressed by x=0.3X (ft/fw-1)), fgd is an absolute value of a movement amount of the front lens group along the optical axis when zooming from the wide-angle end to the telephoto end, the following condition is satisfied:

(iii)X–0.2≤Fgd/fw≤X+0.2。

Condition (iii) defines a movement range of the front lens group suitable for the zoom ratio. If the movement range is below the lower limit of the range, the movement distance of the front lens group during zooming is kept small, but zooming of the inserted rear lens group and aberration correction in the tele state cannot be performed at the same time, a desired zoom ratio cannot be obtained, or a desired imaging performance cannot be obtained. If the movement range exceeds the upper limit of the range, the zoom ratio and imaging performance are more easily obtained, but it is difficult to keep the movement distance of the lens longer at the time of zooming. This makes it difficult to solve the problems of keeping the moving distance of the lens group small at the time of zooming, and suppressing the motor size and cost of the present invention.

Alternatively, the following conditions are satisfied:

(iii)X–0.1≤Fgd/fw≤X+0.1。

According to one aspect of the present switching zoom lens system, when fLo is the focal length of the most object side lens of the front lens group, the most object side lens in the front lens group satisfies the following condition:

(iv)0.5≤fLo/fw≤1.2。

The condition (iv) defines the refractive index of the most image side lens of the front lens group within an appropriate range. If the refractive index is lower than the lower limit, the refractive index of the most image side lens becomes too large, and it is difficult to correct aberrations in a tele state in which the rear group is inserted, and a desired resolution performance cannot be obtained. Still another problem is that in the wide-angle state, the distance from the most image side lens to the imaging surface tends to be too short with respect to the focal length, and the upper limit of condition (iii) is exceeded. If the refractive index exceeds the upper limit of the range, it is easier to obtain the desired resolution performance in the tele state and to satisfy the condition (iii), but there is a problem in that the total length of the lens module itself becomes too long.

Alternatively, the following conditions are satisfied:

(iii)-2 0.65≤fLo/fw≤1.05

according to one aspect of the present switched zoom lens system, focusing is performed by moving the front lens group along the optical axis in the wide-angle state and the telephoto state.

Therefore, focusing is possible regardless of whether there is a rear lens group, i.e., in the wide-angle state and in the telephoto state.

According to one aspect of the present switched zoom lens system, the most image side lens of the front lens group has a negative refractive index, and when fLi is the focal length of the most image side lens of the front lens group, the following condition is satisfied:

(v)fLi/fw≤–0.5。

The condition (v) defines an appropriate range of refractive indices of the most image side lenses in the front lens group. If the refractive index exceeds the upper limit, the angle of the light rays emitted from the front lens group to the rear lens group tends to increase, and there is a problem in that aberration correction in the tele state is not sufficiently achieved, and the desired resolution performance cannot be obtained.

Alternatively, the following conditions are satisfied:

(v)-2fLi/fw≤–0.7。

According to a second aspect, a camera is provided. The camera includes the wide-angle lens optical system and the image sensor provided in the first aspect. The wide-angle lens optical system is used to input light (for carrying image data) to an image sensor, which is used to display an image based on the image data.

According to a third aspect, a terminal is provided. The terminal comprises a camera (i.e. a camera provided in the second aspect) and a graphics processing unit (graphic processing unit, GPU). The GPU is connected to the camera. The camera is used for acquiring image data and inputting the image data into the GPU, and the GPU is used for processing the image data received from the camera. The terminal can be applied to small cameras of mobile equipment such as mobile phones and tablet computers.

The invention will be presented in more detail in accordance with the following description and the accompanying drawings, which show preferred embodiments in accordance with the invention for illustrative purposes only.

Drawings

The invention will be better understood from the following detailed description of non-limiting embodiments of the invention, when viewed in the accompanying drawings.

Fig. 1-1 shows a sectional view of a switched zoom lens according to a first embodiment of the present invention in a wide-angle state.

Fig. 1-2 show a sectional view of a switched zoom lens according to a first embodiment of the present invention in a tele state.

Fig. 1 to 3 show longitudinal spherical aberration, astigmatism field curve, and distortion of a switched zoom lens in a wide-angle state according to a first embodiment of the present invention.

Fig. 1 to 4 show longitudinal spherical aberration, astigmatism field curve, and distortion in a telephoto state of the switched zoom lens according to the first embodiment of the present invention.

Fig. 2-1 shows a sectional view of a switched zoom lens according to a second embodiment of the present invention in a wide-angle state.

Fig. 2-2 show a sectional view of a switched zoom lens according to a second embodiment of the present invention in a tele state.

Fig. 2 to 3 show longitudinal spherical aberration, astigmatism field curve, and distortion of the switched zoom lens in the wide-angle state according to the second embodiment of the present invention.

Fig. 2 to 4 show longitudinal spherical aberration, astigmatism field curve, and distortion in a telephoto state of the switched zoom lens according to the second embodiment of the present invention.

Fig. 3-1 shows a sectional view of a switched zoom lens according to a third embodiment of the present invention in a wide-angle state.

Fig. 3-2 illustrates a sectional view of a switched zoom lens according to a third embodiment of the present invention in a tele state.

Fig. 3 to 3 show longitudinal spherical aberration, an astigmatic field curve, and distortion of the switched zoom lens in the wide-angle state according to a third embodiment of the present invention.

Fig. 3 to 4 show longitudinal spherical aberration, an astigmatic field curve, and distortion of the switched zoom lens in a telephoto state according to a third embodiment of the present invention.

Fig. 4 shows an implementation of the invention.

Detailed Description

The following embodiments of the switched zoom lens system of the present invention are described with reference to the accompanying drawings and optical data. The zoom lens switching system can be applied to small cameras of mobile devices such as mobile phones and tablet computers.

According to the present invention, a switching zoom lens includes, in order from an object side: a reflective optical element for bending an optical path from an object side to an image side, a front lens group, and a rear lens group. The rear lens group is interposed between the front lens group and an imaging surface upon zooming from a wide-angle end to a telephoto end, and is moved out of an optical path of the switching zoom lens upon zooming from the telephoto end to the wide-angle end. The switching zoom lens may be mounted on a mobile device and optically switch the viewing angle between tele and wide without changing the TTL.

First embodiment

Fig. 1-1 shows a sectional view of a switched zoom lens system according to a first embodiment of the present invention in a wide-angle state.

The switching zoom lens system includes a reflective optical element P for bending an optical path from an object side to an image side, a front lens group Gf having a positive refractive index, and a rear lens group Gr. The front lens group Gf includes a first lens element L1, a second lens element L2, a third lens element L3, a fourth lens element L4, a fifth lens element L5, and a sixth lens element L6. The rear lens group Gr includes a seventh lens element L7, an eighth lens element L8, a ninth lens element L9, and a tenth lens element L10. A filter IR (e.g., an infrared cut filter or cover glass) may be disposed on the imaging surface IMG. The filter IR may be omitted.

Fig. 1-1 does not show the rear lens group Gr, because in the wide-angle state, the rear lens group Gr is removed in a direction perpendicular to the optical axis in the front/rear direction of fig. 1-1 and 1-2, so that the movement of the rear lens group Gr does not increase the thickness, i.e., in the upward/downward direction of the drawing. When switching to the telephoto state, the rear group Gr moves and stands still on the optical path, and the optical axis of the rear lens group Gr is aligned with the optical axis OA of the switching zoom lens.

Fig. 1-2 show a sectional view of a switched zoom lens system according to a first embodiment of the present invention in a tele state. For the tele state, the front lens group Gf is moved toward the object side along the optical axis OA, and the rear lens group Gr is moved perpendicularly to the optical axis OA into the optical path between the front lens group Gf and the imaging surface so that the front lens group Gr is arranged around the optical axis OA.

The rear lens group Gr is removed from the optical path perpendicularly to the optical axis OA, and the front lens group Gf is moved back to the wide-angle state along the optical axis OA toward the image side. In other words, the rear lens group Gr is not used in the wide-angle state.

Further, the movement when the rear lens group Gr is removed from the telephoto state to the wide-angle state does not have to be perpendicular to the optical axis of the switching zoom lens. Since the wide-angle rear lens group Gr does not participate in imaging in the wide-angle state, the rear lens group Gr may also be removed in any manner as long as the rear lens group Gr is completely out of the optical path.

The front lens group Gf is also used for focusing by moving along the optical path OA in the wide-angle state and the telephoto state.

In this way, the switched zoom lens of the present invention can be rapidly enlarged and reduced between the wide-angle state and the telephoto state, and the zoom mechanism can be easily designed.

Table 1-1 shows the radius of curvature of each lens element in the wide-angle state and the thickness or spacing of each optical surface, as well as the refractive index and abbe number with respect to the d-line, of the optical lens system according to the first embodiment. The opposite surfaces of each lens element are referred to as surface S1 and surface S2, respectively, in order from the object side to the image side. The symbol "×" indicates that the surface is aspherical. Note that the lens elements L7 to L10 are not on the table, because the rear lens group Gr is not used in the wide-angle state.

TABLE 1-1

Tables 1-2 show the radius of curvature of each lens element in the tele state and the thickness or spacing of each optical surface, as well as the refractive index and abbe number with respect to the d-line, of the optical lens system according to the first embodiment. The opposite surfaces of each lens element are referred to as surface S1 and surface S2, respectively, in order from the object side to the image side. The symbol "×" indicates that the surface is aspherical.

TABLE 1-2

Tables 1 to 3 show the aspherical coefficients of each lens element of the optical lens system according to the first embodiment, wherein numerals 2,4 … … denote higher-order aspherical coefficients. The equation for the aspherical surface profile is expressed as follows:

Wherein:

and z: a distance (sagging amount) from the vertex of the lens surface in the optical axis direction;

H: a height in a direction perpendicular to the optical axis direction;

c: paraxial curvature of the apex of the lens (inverse of the radius of curvature);

Y: a distance from a point on the curve of the aspheric surface to the optical axis;

k: a conic coefficient;

Ai: aspheric coefficients of the i-order.

Table 1-3 aspherical coefficients

FIGS. 1-3 show longitudinal spherical aberration for each wavelength; an astigmatic field curve in which the amount of d-ray aberration on the sagittal image plane S is represented by a solid line and the amount of d-ray aberration on the tangential image plane T is represented by a broken line; the switching zoom lens according to the first embodiment of the present invention is distorted in the wide-angle state, wherein the amount of aberration on the d-line is shown by a solid line.

As can be seen from the graph, each aberration is satisfactorily corrected.

Second embodiment

Fig. 2-1 shows a sectional view of a switched zoom lens system according to a second embodiment of the present invention in a wide-angle state.

Fig. 2-1 does not show the rear lens group Gr, because in the wide-angle state, the rear lens group Gr is removed in a direction perpendicular to the optical axis in the front/rear direction of fig. 2-1 and 2-2, so that the movement of the rear lens group Gr does not increase the thickness, i.e., in the upward/downward direction of the drawing. When switching to the telephoto state, the rear group Gr moves and stands still on the optical path, and the optical axis of the rear lens group Gr is aligned with the optical axis OA of the switching zoom lens.

Fig. 2-2 show a sectional view of a switched zoom lens system according to a second embodiment of the present invention in a tele state. For the tele state, the front lens group Gf is moved toward the object side along the optical axis OA, and the rear lens group Gr is moved perpendicularly to the optical axis OA into the optical path between the front lens group Gf and the imaging surface so that the front lens group Gr is arranged around the optical axis OA.

Table 2-1 shows the radius of curvature of each lens element in the wide-angle state and the thickness or spacing of each optical surface, as well as the refractive index and abbe number with respect to the d-line, of the optical lens system according to the second embodiment. The opposite surfaces of each lens element are referred to as surface S1 and surface S2, respectively, in order from the object side to the image side. The symbol "×" indicates that the surface is aspherical. Note that the lens elements L7 to L10 are not on the table, because the rear lens group Gr is not used in the wide-angle state.

TABLE 2-1

Table 2-2 shows the radius of curvature of each lens element in the tele state and the thickness or spacing of each optical surface, as well as the refractive index and abbe number with respect to the d-line of the optical lens system according to the second embodiment. The opposite surfaces of each lens element are referred to as surface S1 and surface S2, respectively, in order from the object side to the image side. The symbol "×" indicates that the surface is aspherical.

TABLE 2-2

Tables 2-3 show the aspherical coefficients of each lens element of the optical lens system according to the second embodiment, wherein numerals 2,4 … … denote higher-order aspherical coefficients.

Table 2-3 aspherical coefficients

FIGS. 2-3 show longitudinal spherical aberration for each wavelength; an astigmatic field curve in which the amount of d-ray aberration on the sagittal image plane S is represented by a solid line and the amount of d-ray aberration on the tangential image plane T is represented by a broken line; the switching zoom lens according to the second embodiment of the present invention is distorted in the wide-angle state, wherein the amount of aberration on the d-line is shown by a solid line.

As can be seen from the graph, each aberration is satisfactorily corrected.

Third embodiment

Fig. 3-1 shows a sectional view of a switched zoom lens system according to a third embodiment of the present invention in a wide-angle state.

The switching zoom lens system includes a reflective optical element P for bending an optical path from an object side to an image side, a front lens group Gf having a positive refractive index, and a rear lens group Gr. The front lens group Gf includes a first lens element L1, a third lens element L2, a third lens element L3, a fourth lens element L4, a fifth lens element L5, and a sixth lens element L6. The rear lens group Gr includes a seventh lens element L7, an eighth lens element L8, a ninth lens element L9, and a tenth lens element L10. A filter IR (e.g., an infrared cut filter or cover glass) may be disposed on the imaging surface IMG. The filter IR may be omitted.

Fig. 3-2 illustrates a sectional view of a switched zoom lens system according to a third embodiment of the present invention in a tele state. For the tele state, the front lens group Gf is moved toward the object side along the optical axis OA, and the rear lens group Gr is moved perpendicularly to the optical axis OA into the optical path between the front lens group Gf and the imaging surface so that the front lens group Gr is arranged around the optical axis OA.

Table 3-1 shows the radius of curvature of each lens element in the wide-angle state and the thickness or spacing of each optical surface, as well as the refractive index and abbe number with respect to the d-line, of the optical lens system according to the third embodiment. The opposite surfaces of each lens element are referred to as surface S1 and surface S2, respectively, in order from the object side to the image side. The symbol "×" indicates that the surface is aspherical. Note that the lens elements L7 to L10 are not on the table, because the rear lens group Gr is not used in the wide-angle state.

TABLE 3-1

Table 3-2 shows the radius of curvature of each lens element in the tele state and the thickness or spacing of each optical surface, as well as the refractive index and abbe number with respect to the d-line of the optical lens system according to the third embodiment. The opposite surfaces of each lens element are referred to as surface S1 and surface S2, respectively, in order from the object side to the image side. The symbol "×" indicates that the surface is aspherical.

TABLE 3-2

Table 3-3 shows the aspherical coefficients of each lens element of the optical lens system according to the third embodiment, wherein numerals 2,4 … … denote higher-order aspherical coefficients.

Table 3-3 aspherical coefficients

3-3 Show the longitudinal spherical aberration for each wavelength; an astigmatic field curve in which the amount of d-ray aberration on the sagittal image plane S is represented by a solid line and the amount of d-ray aberration on the tangential image plane T is represented by a broken line; the switching zoom lens according to the third embodiment of the present invention is distorted in the wide-angle state, wherein the amount of aberration on the d-line is shown by a solid line.

As can be seen from the graph, each aberration is satisfactorily corrected. Further, with respect to the term used in the present invention, the refractive index refers to the refractive index along the paraxial (near the optical axis).

As shown in the above optical data, the switched zoom lens system of the present invention can provide high-speed optical magnification variation while avoiding the use of a mechanism and a costly zoom motor to move a lens group for zooming largely along the optical axis, and also can achieve high image quality and compactness. The switching zoom lens in these embodiments achieves preferable effects by satisfying the following conditions:

(i)1.2≤ft/fw≤3，

where ft is the focal length of the switching zoom lens in the telephoto state, and fw is the focal length of the switching zoom lens in the wide-angle state.

(ii)16.5°≤FOVw≤28.5°，

Wherein FOVw is the angle of view of the switched zoom lens in the wide-angle state.

(iii)X–0.2≤Fgd/fw≤X+0.2，

Where X is a zoom ratio between the wide-angle state and the telephoto state, denoted by x=0.3X (ft/fw-1), fgd is an absolute value of a movement amount of the front lens group along the optical axis when zooming from the wide-angle end to the telephoto end.

(iv)0.5≤fLo/fw≤1.2，

Where fLo is a focal length of the most object side lens of the front lens group.

(v)fLi/fw≤–0.5，

Wherein fLi is a focal length of the most image side lens of the front lens group.

Condition (i) defines a zoom ratio between the wide-angle state and the telephoto state. If the zoom ratio is below the lower limit of the range, it is easier to design the shot, but the zoom ratio is too small to provide the desired user experience. If the zoom ratio exceeds the upper limit of the range, the user will understand a large zoom ratio, but the F-number becomes too large due to the characteristic of an optical system called a periscope type in which the aperture is limited, which results in degradation of resolution performance due to diffraction limitation. Further, when the zoom ratio becomes large, the movement amount of the front lens group required to change the magnification increases. This makes it difficult to solve the problems of keeping the moving distance of the lens group small at the time of zooming and suppressing the motor size and cost of the present invention. From this point of view, the following condition can be selectively satisfied.

(i)-21.25≤ft/fw≤2.5

Condition (ii) defines a viewing angle in the wide-angle state. If the angle of view is below the lower limit of the range, the angle of view in the wide-angle state becomes too narrow to be considered wide. In contrast, if the angle of view exceeds the upper limit of the range, the angle of view in the wide-angle state becomes too large to be a periscope type system. In particular, vignetting occurs at the peripheral viewing angle on the reflective optical element. From this point of view, the following condition can be selectively satisfied.

(ii)-218.5°≤FOVw≤26.5°

Condition (iii) defines a movement range of the front lens group suitable for the zoom ratio. If the movement range is below the lower limit of the range, the movement distance of the front lens group during zooming is kept small, but zooming of the inserted rear lens group and aberration correction in the tele state cannot be performed at the same time, a desired zoom ratio cannot be obtained, or a desired imaging performance cannot be obtained. If the movement range exceeds the upper limit of the range, the zoom ratio and imaging performance are more easily obtained, but it is difficult to keep the movement distance of the lens longer at the time of zooming. This makes it difficult to solve the problems of keeping the moving distance of the lens group small at the time of zooming and suppressing the motor size and cost of the present invention. From this point of view, the following condition can be selectively satisfied.

(iii)-2X-0.1≤Fgd/fw≤X+0.1

The condition (iv) defines the refractive index of the most image side lens of the front lens group within an appropriate range. If the refractive index is lower than the lower limit, the refractive index of the most image side lens becomes too large, and it is difficult to correct aberrations in a tele state in which the rear group is inserted, and a desired resolution performance cannot be obtained. Still another problem is that in the wide-angle state, the distance from the most image side lens to the imaging surface tends to be too short with respect to the focal length, and the upper limit of condition (iii) is exceeded. If the refractive index exceeds the upper limit of the range, it is easier to obtain the desired resolution performance in the tele state and to satisfy the condition (iii), but there is a problem in that the total length of the lens module itself becomes too long. From this point of view, the following condition can be selectively satisfied.

(iv)-20.65≤fLo/fw≤1.05

The condition (v) defines an appropriate range of refractive indices of the most image side lenses in the front lens group. If the refractive index exceeds the upper limit, the angle of the light rays emitted from the front lens group to the rear lens group tends to increase, and there is a problem in that aberration correction in the tele state is not sufficiently achieved, and the desired resolution performance cannot be obtained. From this point of view, the following condition can be selectively satisfied.

(v)-2fLi/fw≤-0.7

Table 4 shows values of parameters used in the above conditions of the first, second, and third embodiments.

TABLE 4 Table 4

Parameters (parameters)	Ex.1	Ex.2	Ex.3
				ft/fw	1.600	1.300	2.000
FOVw(°)	22.509	22.503	22.517
				Fgd/fw	0.206	0.107	0.297
fLo/fw	0.766	0.962	0.853
				fLi/fw	-0.890	-1.664	-1.846

By satisfying these conditions, the size of the switching zoom lens of the present invention can be compact, can be mounted on a mobile device, and can optically switch a viewing angle between a telephoto and a wide angle without changing TTL. By using such a switched zoom lens module, high-speed optical magnification variation can be provided while avoiding the use of a mechanism and costly zoom motor to move the lens group for zooming substantially along the optical axis. The switching zoom lens may also be configured as a periscope type by bending the optical path from the object using a reflective optical element. The periscope type is advantageous for reducing the height of the lens module.

Furthermore, a camera is provided. The camera in the invention comprises the switching zoom lens and the image sensor. The switching zoom lens is used to input light for projecting an image to an image sensor, which is used to convert the image into digital image data.

Fig. 4 shows a terminal 1000 as disclosed in the present invention. Terminal 1000 can include camera 100 and graphics processing unit (graphic processing unit, GPU) 200 provided in the implementations described above. The camera 100 is used to convert an image passing through the present invention's zoom lens and input the digital image data into the GPU 200, and the GPU 200 is used to process the image data received from the camera.

In fig. 4, terminal 1000 includes two cameras 100. The terminal may include a single camera or more than two cameras and it (or they) may be connected to a single GPU 200. One of the cameras 100 may be combined with the present invention's switched zoom lens, while the other camera 100 may be combined with a different type of lens (e.g., a single focus wide angle lens).

Although the lens system according to the present invention may be particularly applicable to a mobile phone camera, it may also be applicable to a camera in any mobile device (e.g. tablet device and wearable device).

Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims

1. A switched zoom lens, characterized by comprising, along an optical axis from an object side to an image side:

A reflective optical element for bending an optical path from the object side to the image side;

A front lens group having a positive refractive index;

a rear lens group including three or more and five or less lens elements;

Wherein the rear lens group is interposed between the front lens group and an imaging surface upon zooming from a wide-angle end to a telephoto end, the rear lens group being moved out of an optical path of the switching zoom lens upon zooming from the telephoto end to the wide-angle end,

The following conditions are satisfied:

(i)1.2≤ft/fw≤3；

(ii)16.5°≤FOVw≤28.5°，

Where ft is a focal length of the switching zoom lens in a telephoto state, fw is a focal length of the switching zoom lens in a wide-angle state, and FOVw is a field angle of the switching zoom lens in the wide-angle state.

2. The switched zoom lens of claim 1, wherein the following condition is satisfied:

(i)-2 1.25≤ft/fw≤2.5；

(ii)-2 18.5°≤FOVw≤26.5°。

3. the switched zoom lens according to claim 1 or 2, wherein upon zooming, the following condition is satisfied:

(iii)X–0.2≤Fgd/fw≤X+0.2，

4. A switched zoom lens according to claim 3, wherein upon zooming, the following conditions are satisfied:

(iii)-2X–0.1≤Fgd/fw≤X+0.1。

5. the switched zoom lens of any one of claims 1 to 4, wherein an object-side lens in the front lens group satisfies the following condition:

(iv)0.5≤fLo/fw≤1.2，

6. The switched zoom lens of claim 5, wherein the following condition is satisfied:

(iv)-2 0.65≤fLo/fw≤1.05。

7. the switched zoom lens of any one of claims 1 to 6, wherein focusing is performed by moving the front lens group along the optical axis at the wide angle end and the telephoto end.

8. The switching zoom lens according to any one of claims 1 to 7, wherein the most image side lens of the front lens group has a negative refractive index, and the following condition is satisfied:

(v)fLi/fw≤–0.5，

9. The switched zoom lens of claim 8, wherein the following condition is satisfied:

(v)-2fLi/fw≤–0.7。

10. a camera module comprising the switched zoom lens according to any one of claims 1 to 9, further comprising an image sensor, wherein the image sensor is provided on an image side of the switched zoom lens for forming an optical signal of a subject and reflecting the optical signal to the image sensor, the image sensor for converting the optical signal corresponding to the subject into an image signal.

11. A terminal comprising a camera module according to claim 10 and a graphics processing unit (graphic processing unit, GPU) connected with the camera module to receive and process the image signals.