JP7185187B2 - Imaging optical system and imaging device - Google Patents

Description

The present invention relates to a compact image pickup optical system and an image pickup apparatus incorporating the same, and more particularly to an image pickup optical system and image pickup apparatus suitable for reducing the height.

In recent years, cameras for smartphones are equipped with a wide lens and a tele lens. Among these lenses, the tele lens has a long focal length, so the size in the thickness direction of the smartphone is very severely restricted in terms of design. For this reason, there has been proposed a bent type tele-lens in which the height is reduced by bending the optical path with a prism (see, for example, Patent Documents 1 and 2). In these lenses, the height of the bent type lens is further reduced, and some of the members constituting the tele lens are composed of non-circular diaphragms and lenses. Specifically, in Japanese Unexamined Patent Application Publication No. 2002-100002, in a bending imaging optical system, a large-diameter lens that maximizes the effective radius of an axial light beam is made non-circular. Further, in Patent Document 2, a non-circular aperture member is provided between an object and a lens or between the lens and an imaging surface.

However, in the lens of Patent Document 1, only the lens having the maximum effective radius of the on-axis light beam is non-circular, and the effective diameter of the lens including the off-axis light beam is not mentioned. Therefore, in the lens of Patent Document 1, a reduction in the height of the entire lens system has not been achieved. In addition, in the lens of Patent Document 2, only the shape of the aperture member is non-circular, and the overall height of the lens system has not been reduced.

JP 2015-79047 A U.S. Patent 2019/0041554

SUMMARY OF THE INVENTION It is an object of the present invention to provide an imaging optical system in which the height of the entire lens system is reduced.

Another object of the present invention is to provide an imaging apparatus incorporating the imaging optical system described above.

In order to achieve the above object, an imaging optical system according to the present invention includes an aperture stop and a plurality of lenses, wherein the aperture of the aperture stop and the optical surfaces of at least one or more lenses out of the plurality of lenses are non-uniform. is circular in shape,
the aperture stop is arranged on the object side of the lens closest to the object side among the plurality of lenses, and is provided independently from the lens closest to the object side;
The lens has a pair of linear edges extending in parallel, the direction parallel to the pair of parallel edges is the width direction, and the direction perpendicular to the pair of parallel edges is the height direction,
An aperture stop and all lenses having a non-circular shape among the plurality of lenses satisfy the following conditional expression.
0.5<Dyape/Dxape<1.0 (1)
Dylens/Dyepd<1.2 (2)
However, the value Dxape is the length in the width direction of the aperture of the aperture stop, the value Dyape is the length in the height direction of the aperture of the aperture stop, and the value Dylens is the upper limit of the total number of lenses having a non-circular shape. The optical surface diameter in the height direction of the i-th lens having a non-circular shape, where i is an arbitrary natural number , and the value Dyepd is the entrance pupil diameter in the height direction of the entire plurality of lenses . It should be noted that the aperture stop and lens having non-circular shapes also have non-circular outer shapes.

In the above imaging optical system, the opening of the aperture stop and the optical surface of at least one lens are formed in a non-circular shape, so that a predetermined direction (specifically, the height of the lens length) is shortened, and the length in the direction perpendicular to the predetermined direction (specifically, the width direction of the lens), which is the direction in which size restrictions are loose, is lengthened. As a result, even if the length in a predetermined direction is shorter than that of a circular optical system having a circular aperture diaphragm and a plurality of lenses, the circular optical system having a longer length in the height direction than an optical system having a non-circular shape can be obtained. An optical system that secures the same F-number as the system can be achieved. Here, the same F-number means that the entrance pupil areas are the same. When the aperture stop or the optical surface of the lens has a circular shape, matching the F-number with an optical system having a non-circular shape results in a diameter larger than the height of the optical system having a non-circular shape.

Conditional expression (1) is for appropriately setting the shape of the aperture stop. When the value Dyape/Dxape of conditional expression (1) is less than the upper limit, the length in a predetermined direction (specifically, the height direction of the lens) is reduced in the direction perpendicular to the predetermined direction (specifically, the width of the lens). direction), and an optical system having a short length in a predetermined direction can be configured. On the other hand, when the value Dyape/Dxape of conditional expression (1) exceeds the lower limit, the difference in resolving power between the predetermined direction and the direction orthogonal to the predetermined direction due to the difference in diffraction limit between the two directions does not become too large.

Conditional expression (2) is for appropriately setting the optical surface diameter of a lens having a non-circular shape. When the value Dylens/Dyepd of conditional expression (2) is below the upper limit, the optical surface diameter of the lens having a non-circular shape in a predetermined direction (specifically, the height direction of the lens) becomes larger than the entrance pupil diameter. In addition, the length in the predetermined direction can be shortened in the entire lens system from the object side to the image plane side.

According to a specific aspect of the present invention, the imaging optical system described above satisfies the following conditional expression.
0.3<LL/TTL<0.8 (3)
However, the value LL is the distance on the optical axis from the most object-side lens surface to the image-side lens surface among the plurality of lenses, and the value TTL is the distance from the most object-side lens surface to the image-side focal point among the plurality of lenses. is the distance on the optical axis to

Conditional expression (3) is for appropriately setting the lens length. When the value LL/TTL of conditional expression (3) is less than the upper limit, the optical surface diameter of the lens on the image side can be reduced while ensuring telecentricity, and an optical system with a small diameter can be achieved. On the other hand, when the value LL/TTL of conditional expression (3) exceeds the lower limit, it is possible to ensure an appropriate thickness and interval between the lenses, to ensure moldability and workability, and to facilitate manufacturing.

According to another aspect of the present invention, the aperture stop is arranged on the object side of the lens closest to the object side among the plurality of lenses. In this case, the diameter of the optical surface of the lens closest to the object side does not become too large with respect to the diameter of the entrance pupil, and an optical system with a small diameter can be achieved.

According to yet another aspect of the invention, there is a bending element between the object and the image plane position. In this case, a predetermined direction (specifically, the height direction of the lens) can be set in any direction by the bending element, and by shortening the length in the predetermined direction, the height can be reduced in any direction. becomes.

According to still another aspect of the present invention, the aperture stop and the non-circular lens among the plurality of lenses are perpendicular to the height direction of the lens so that the length of the circular lens in the height direction is short. It has a shape cut by the line drawn. In this case, the chipped shape based on a circular shape is more advantageous than the chipped shape based on an elliptical shape in securing the area of the incident light beam. It should be noted that it is easier and more accurate to manufacture by cutting a circle along a line than by directly manufacturing a chipped shape.

According to yet another aspect of the invention, all lenses of the plurality of lenses have non-circular shapes. In this case, the length of the entire lens system from the object side to the image plane side in a predetermined direction (for example, the height direction of the lens) can be minimized.

According to still another aspect of the present invention, the plurality of lenses are composed of 5 or more lenses. In the case of the same F-number, a non-circular aperture diaphragm has a shorter length in a predetermined direction (specifically, the height direction of the lens) and a direction perpendicular to the predetermined direction. (Specifically, the length in the width direction of the lens) is increased. In an optical system with a non-circular aperture stop, it is more difficult to correct aberrations in a direction perpendicular to a predetermined direction (specifically, in the width direction of the lens) than in an optical system with a circular aperture stop. Aberration correction is made efficient by adopting a lens configuration of

According to still another aspect of the present invention, a light shielding member arranged between an object and an image plane position and a frame member holding a plurality of lenses are provided, and an opening of the light shielding member and an opening of the frame member are provided. A section has a non-circular shape. To prevent the length in a predetermined direction (specifically, the height direction of the lens) from increasing due to members other than the aperture diaphragm and the lens by making the light shielding member and the frame member non-circular. can be done. The outer shapes of the light shielding member and the frame member having non-circular shapes are also non-circular.

In order to achieve the above object, an imaging apparatus according to the present invention includes the imaging optical system described above and an imaging device that detects an image obtained from the imaging optical system.

By using the imaging optical system described above, the above-described imaging apparatus can achieve a low profile.

It is a figure explaining an imaging device provided with the imaging optical system of one embodiment of the present invention. 2 is an exploded perspective view of the imaging optical system of FIG. 1; FIG. (A) is a cross-sectional view in the width direction of the lens of the imaging optical system in FIG. 1, (B) is a cross-sectional view in the height direction of the lens of the imaging optical system, and (C) is an aperture diaphragm. FIG. 4 is a plan view of an opening; (A) and (B) are front and rear perspective views of the mobile communication terminal, respectively. (A) is a conceptual diagram explaining the F-number of an imaging optical system as an embodiment, and (B) is a conceptual diagram explaining the F-number of an imaging optical system as a comparative example. (A) is a cross-sectional view in the width direction of the lens of the imaging optical system of Example 1; (B) is a cross-sectional view in the height direction of the lens of the imaging optical system of Example 1; 4] is a plan view of the aperture of the aperture stop of Example 1. [FIG. (A) is a cross-sectional view in the width direction of the lens of the imaging optical system of Example 2; (B) is a cross-sectional view in the height direction of the lens of the imaging optical system of Example 2; 10] is a plan view of the aperture of the aperture stop of Example 2. [FIG. (A) is a cross-sectional view in the width direction of the lens of the imaging optical system of Example 3; (B) is a cross-sectional view in the height direction of the lens of the imaging optical system of Example 3; 10] is a plan view of the aperture of the aperture stop of Example 3. [FIG. (A) is a cross-sectional view in the width direction of the lens of the imaging optical system of Example 4; (B) is a cross-sectional view in the height direction of the lens of the imaging optical system of Example 4; 10] is a plan view of the aperture of the aperture stop of Example 4. [FIG.

An imaging optical system and an imaging apparatus according to an embodiment of the present invention will be described below with reference to FIG. 1 and the like. The imaging optical system 10 illustrated in FIG. 1 has the same configuration as the imaging optical system 10A of Example 1, which will be described later. A mobile communication terminal, which will be described later, is equipped with a wide lens and a tele lens as an imaging optical system, but the following description will be given mainly assuming the tele lens. However, the imaging optical system 10 according to the present invention is not limited to a tele lens, and a wide lens may have a similar configuration.

FIG. 1 is a cross-sectional view showing an imaging device 100 that is one embodiment of the present invention. The imaging device 100 includes a camera module 30 for forming an image signal, and a processing unit 60 that functions as the imaging device 100 by operating the camera module 30 .

The camera module 30 includes a lens unit 40 that incorporates the imaging optical system 10, and a sensor section 50 that converts a subject image formed by the imaging optical system 10 into an image signal.

The lens unit 40 includes the imaging optical system 10 and a frame member 41 attached to the imaging optical system 10 . The imaging optical system 10 forms a subject image on an imaging plane (image plane) I of the imaging element 51 . Although details will be described later, the imaging optical system 10 includes, in order from the object side, an aperture diaphragm ST, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, and a fifth lens L5. and As shown in FIGS. 2, 3A, and 3B, light blocking members SH1 to SH3 are provided between the lenses. In addition, as shown in FIGS. 1, 3A, and 3B, the imaging optical system 10 includes a bending element PR that bends the optical path toward the object side. The bending element PR is positioned and fixed with respect to the optical axis AX by a fixing member (not shown). The frame member 41 accommodates and holds lenses and the like inside. The frame member 41 has an opening OP through which light from the object side is incident. The frame member 41 enables the focusing operation of the imaging optical system 10 by moving one or more lenses among the lenses L1 to L5 constituting the imaging optical system 10 along the optical axis AX. Therefore, it has a drive mechanism 42, for example. The drive mechanism 42 reciprocates a specific lens or all lenses along the optical axis AX. The drive mechanism 42 includes, for example, a voice coil motor and guides. The drive mechanism 42 can be configured by a stepping motor or the like instead of the voice coil motor or the like.

The sensor unit 50 includes an imaging device (solid-state imaging device) 51 that photoelectrically converts a subject image formed by the imaging optical system 10 and a substrate 52 that supports the imaging device 51 . The imaging element 51 is, for example, a CMOS image sensor. The substrate 52 includes wiring, peripheral circuits, and the like for operating the imaging device 51 . The imaging device 51 is positioned and fixed with respect to the optical axis AX by a support member 53 . The support member 53 is fixed in a positioned state so as to fit into the frame member 41 of the lens unit 40 .

The imaging element 51 has a photoelectric conversion section 51a as an imaging surface I, and a signal processing circuit (not shown) is formed around it. Pixels, that is, photoelectric conversion elements are two-dimensionally arranged in the photoelectric conversion portion 51a. Note that the imaging element 51 is not limited to the CMOS type image sensor described above, and may incorporate another imaging element such as a CCD.

A parallel plate or the like can be arranged between the lens unit 40 and the sensor section 50 . The parallel flat plate is assumed to be an optical low-pass filter, an IR cut filter, a seal glass of the imaging element 51, or the like.

The processing unit 60 includes a lens driving unit 61 , an element driving unit 62 , an input unit 63 , a storage unit 64 , an image processing unit 65 , a display unit 66 and a control unit 67 . The lens drive unit 61 operates the drive mechanism 42 to move one or more of the first to fifth lenses L1 to L5 along the optical axis AX, thereby focusing the imaging optical system 10. and so on. The device drive unit 62 operates the image pickup device 51 by receiving voltages and clock signals for driving the image pickup device 51 from the control unit 67 and outputting them to circuits associated with the image pickup device 51 . Under the control of the control unit 67, the device driving unit 62 outputs YUV and other digital pixel signals from the imaging device 51 as they are or after processing them to the image processing unit 65 or an external circuit. The input unit 63 is a part that receives a user's operation or a command from an external device. The storage unit 64 is a part that stores information necessary for the operation of the imaging device 100, image data acquired by the camera module 30, lens correction data used for image processing, and the like. The image processing unit 65 performs image processing on the image signal output from the imaging device 51 . In the image processing unit 65, the image signal corresponds to, for example, a moving image, and the frame image forming the moving image is processed. The image processing unit 65 performs distortion correction processing on the image signal based on the lens correction data read out from the storage unit 64 in addition to normal image processing such as color correction, tone correction, and zooming. The display unit 66 is a part that displays information to be presented to the user, captured images, and the like. The display unit 66 can also function as the input unit 63 , and the mobile communication terminal 300 described later can be operated via the display unit 66 . The control unit 67 comprehensively controls operations of the lens driving unit 61, the element driving unit 62, the input unit 63, the storage unit 64, the image processing unit 65, the display unit 66, and the like. Various image processing can be performed on the image data.

Next, an example of a mobile communication terminal 300 such as a mobile phone equipped with the camera module 30 illustrated in FIG. 1 will be described with reference to FIGS. 4(A) and 4(B).

The mobile communication terminal 300 is a smartphone-type mobile terminal and includes an imaging device 100 having a camera module 30 . Although illustration is omitted, the mobile communication terminal 300 includes a tele lens 110A and a wide lens 110B as an imaging optical system. Of these, the tele lens 110A has the configuration of the imaging optical system 10 described above. Here, the thickness direction of the mobile communication terminal 300 and the height direction y of the lens of the imaging optical system 10 substantially match. In the imaging apparatus 100, when the imaging optical system 10 has the tele lens 110A and the wide lens 110B, the processing unit 60 may be shared by the tele lens 110A and the wide lens 110B. The mobile communication terminal 300 also includes a wireless communication unit for realizing various information communication with an external system or the like via an antenna (not shown), an operation unit including a power switch, a system program, various processing programs, and a terminal. It also has a storage unit (ROM) or the like that stores necessary data such as an ID. Note that the wide lens 110B may have a circular shape or a non-circular shape.

Note that the imaging device 100 described above is an example of an imaging device suitable for the present invention, and the present invention is not limited to this. That is, the imaging device 100 incorporating the camera module 30 or the imaging optical system 10 is not limited to being built in the smartphone-type mobile communication terminal 300, but is also built in a mobile phone, a PHS (Personal Handyphone System), or the like. It may be built in a PDA (Personal Digital Assistant), a tablet computer, a mobile computer, a digital still camera, a video camera, or the like.

Hereinafter, referring back to FIGS. 1, 2, and 3(A) to 3(C), the imaging optical system 10, which is one embodiment of the present invention, will be described in detail. The imaging optical system 10 includes, in order from the object side, a bending element PR, an aperture stop ST, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, and a fifth lens L5. becomes substantial from That is, the aperture stop ST is arranged on the object side of the first lens L1, which is the lens closest to the object side among the plurality of lenses. As a result, the optical surface diameter of the first lens L1 does not become too large with respect to the diameter of the entrance pupil, and an optical system with a small diameter can be achieved. As shown in FIG. 2, the first and fifth lenses L1 to L5 each have an optical portion 11 and a flange portion 12. As shown in FIG. The optical section 11 has optical surfaces on the object side and the image side, respectively. The optical surface diameter of a lens means the length in a specific direction (width direction x or height direction y) of an optical surface on which an on-axis light beam and an off-axis light beam are incident. The entrance pupil diameter also means the length in the same specific direction as the optical surface diameter.

It should be noted that the plurality of lenses that constitute the imaging optical system 10 are preferably composed of five or more lenses as described above. In the case of the same F-number, the length in a predetermined direction (specifically, the height direction y or lateral direction of the lens) is shorter with a non-circular aperture diaphragm diameter than with a circular aperture diaphragm diameter. The length in the direction perpendicular to the direction (specifically, the width direction x or the longitudinal direction of the lens) increases. Here, although the details will be described later, the same F-number means that the entrance pupil areas are the same. In an optical system having a non-circular aperture stop ST, it is more difficult to correct aberrations in a direction perpendicular to a predetermined direction (specifically, the width direction x of the lens) than in an optical system having a circular aperture stop. Efficient correction of aberrations is achieved by using a lens configuration of at least one lens.

In the imaging optical system 10, the aperture 13 of the aperture stop ST and the optical surfaces of at least one lens among the plurality of lenses have a non-circular shape. It should be noted that the aperture stop ST and lens having non-circular shapes also have non-circular outer shapes. In the illustrated example, the optical surfaces of all of the plurality of lenses (first to fifth lenses L1 to L5) have non-circular shapes. This makes it possible to minimize the length of the entire lens system from the object side to the image plane side in a predetermined direction (specifically, the height direction y of the lens).

The aperture 13 of the aperture stop ST having a non-circular shape and the optical surface of the lens (specifically, the first to fifth lenses L1 to L5) have a shorter length in the height direction y of the circular lens. It has a chipped shape cut along a line perpendicular to the height direction y of the lens. As shown in FIG. 3C, the chipped shape has a straight line portion SL parallel to the width direction x. A chipped shape based on a circular shape is more advantageous than a chipped shape based on an elliptical shape in securing an area for an incident light beam. It should be noted that it is easier and more accurate to manufacture by cutting a circle along a line than by directly manufacturing a chipped shape.

Note that the ratio of the width direction x to the height direction y with respect to the optical surface of the lens having a non-circular shape approximates the ratio of the width direction x to the height direction y with respect to the aperture 13 of the aperture stop ST. is preferred. Further, it is more preferable that the aperture 13 of the aperture stop ST having a non-circular shape and the optical surface of the lens have similar dimensions in the width direction x and the height direction y.

As shown in FIG. 3B and the like, in the imaging optical system 10, the bending element PR that bends the optical path is formed of a prism, a plane reflecting mirror, or the like, and is provided between the object and the image plane position. . As a result, a predetermined direction (specifically, the height direction y of the lens) can be arbitrarily set by the bending element PR. becomes possible. In the illustrated example, the bending element PR is provided on the object side of the imaging optical system 10, bends light incident from the height direction y of the lens, and directs the imaging optical system perpendicular to the height direction y and the width direction x of the lens. 10 in the longitudinal direction z.

As shown in FIG. 2 and the like, in the imaging optical system 10, the light blocking members SH1 to SH3 are arranged between the object side and the image plane position. In the illustrated example, a first light shielding member SH1 is provided between the first lens L1 and the second lens L2, a second light shielding member SH2 is provided between the second lens L2 and the third lens L3, and a second light shielding member SH2 is provided between the second lens L2 and the third lens L3. A third light shielding member SH3 is provided between the third lens L3 and the fourth lens L4. The light shielding members SH1 to SH3 prevent ghosts and flares that may occur in the imaging optical system 10. FIG.

The openings 14 of the light shielding members SH1 to SH3 and the openings 15 of the frame member 41 have non-circular shapes. As a result, the length in a predetermined direction (specifically, the height direction y of the lens) increases due to members other than the aperture stop ST and the lens (that is, the light shielding members SH1 to SH3 and the frame member 41). can be prevented. The outer shapes of the light shielding members SH1 to SH3 and the frame member 41 having non-circular shapes are also non-circular.

The imaging optical system 10 satisfies the following conditional expressions.
0.5<Dyape/Dxape<1.0 (1)
Dylens/Dyepd<1.2 (2)
However, the value Dxape is the length of the aperture 13 of the aperture stop ST in the width direction x, the value Dyape is the length of the aperture 13 of the aperture stop ST in the height direction y, and the value Dylens is the length of the plurality of lenses. Among them, the lens having a non-circular shape (first to fifth lenses L1 to L5 in the illustrated example) is the optical surface diameter in the height direction y, and the value Dyepd is the entrance pupil diameter in the height direction y of the lens. . Note that the width direction x of the aperture stop ST and the width direction x of the lens match, and the height direction y of the aperture stop ST and the height direction y of the lens match.

Conditional expression (1) is for appropriately setting the shape of the aperture stop ST. When the value Dyape/Dxape of conditional expression (1) is less than the upper limit, the length in a predetermined direction (specifically, the height direction y of the lens) is reduced in a direction orthogonal to the predetermined direction (specifically, the length of the lens It is shorter than the length in the width direction x), and an optical system having a short length in a predetermined direction can be configured. On the other hand, when the value Dyape/Dxape of conditional expression (1) exceeds the lower limit, the difference in resolving power between the predetermined direction and the direction orthogonal to the predetermined direction due to the difference in diffraction limit between the two directions does not become too large.

Conditional expression (2) is for appropriately setting the optical surface diameter of a lens having a non-circular shape. When the value Dylens/Dyepd of conditional expression (2) is below the upper limit, the optical surface diameter of the lens having a non-circular shape in a predetermined direction (specifically, the height direction y of the lens) becomes larger than the entrance pupil diameter. The length in the predetermined direction can be shortened in the entire lens system from the object side to the image plane side.

The imaging optical system 10 satisfies the following conditional expressions.
0.3<LL/TTL<0.8 (3)
However, the value LL is from the most object-side lens surface (specifically, the object-side surface of the first lens L1) to the image-side lens surface (specifically, the image-side surface of the fifth lens) among the plurality of lenses. is the distance on the optical axis AX, and the value TTL is the distance on the optical axis AX from the lens surface closest to the object side of the plurality of lenses to the focal point on the image side.

Conditional expression (3) is for appropriately setting the lens length. When the value LL/TTL of conditional expression (3) is below the upper limit, it is possible to reduce the optical surface diameter of the image-side lens (specifically, the fifth lens L5) while ensuring telecentricity. An optical system with a small diameter can be used. On the other hand, when the value LL/TTL of conditional expression (3) exceeds the lower limit, it is possible to ensure an appropriate thickness and interval between the lenses, to ensure moldability and workability, and to facilitate manufacturing.

The F number of the imaging optical system will be described below with reference to FIGS. 5(A) and 5(B). FIG. 5A is a conceptual diagram explaining the F-number of the imaging optical system 10 as an embodiment, and FIG. 5B is a conceptual diagram explaining the F-number of the imaging optical system as a comparative example. . FIGS. 5(A) and 5(B) show the central incident beam at the opening of the aperture stop. In the case of an optical system having the same focal length, if the areas of the center incident light beams IL1 and IL2 of the aperture stop shown in the embodiment and the comparative example are made the same, the F numbers of both can be made the same. Specific examples are shown below.

In the imaging optical system 10 as an embodiment shown in FIG. 5A, the aperture 13 of the aperture stop ST and the optical surfaces of the plurality of lenses have a non-circular shape, and the circular shape extends in the height direction of the lens. It has a chipped shape cut by a line with respect to y. In FIG. 5A, the central incident light beam IL1 of the aperture stop ST has a length Wx (or a diameter in a circular shape) of 4.5 mm in the width direction x of the lens, and a length Wx of 4.5 mm in the height direction y of the lens. The length Hy is 3.6 mm. On the other hand, in the imaging optical system as a comparative example shown in FIG. 5B, the aperture of the aperture stop ST1 and the optical surfaces of the plurality of lenses have a circular shape. In FIG. 5B, the central incident light beam IL2 of the aperture stop ST1 of the comparative example has, for example, a length Wx in the width direction x of the lens and a length Hy in the height direction y of the lens (that is, the diameter of the circular shape). 4.3 mm. The focal lengths of the imaging optical systems shown in the embodiment and the comparative example are both 12 mm. Therefore, the central incident light beams IL1 and IL2 of the aperture stop shown in the embodiment and the comparative example have the same area and the same focal length, and as a result, the F-number of the imaging optical system shown in the embodiment and the comparative example is Both are the same 2.8. That is, even if the imaging optical system 10 according to the embodiment cuts a circular shape in a predetermined direction into a linear shape, the F You can secure your number.

In the imaging optical system described above, the aperture 13 of the aperture stop ST and the optical surface of at least one lens out of the plurality of lenses are formed in a non-circular shape, so that the (Specifically, the length in the height direction y of the lens) is shortened, and the length in the direction (specifically, the width direction x of the lens) perpendicular to a predetermined direction in which size restrictions are relaxed lengthening the As a result, the length in a predetermined direction (specifically, the height direction y of the lens) (that is, the length in the thickness direction of the mobile communication terminal 300) can be obtained from a circular optical system having a circular aperture diaphragm and a plurality of lenses. ) is shortened, it is possible to achieve an optical system that secures the same F-number as a circular optical system having a longer length in the height direction than an optical system having a non-circular shape. If the aperture of the aperture stop ST or the optical surface of the lens has a circular shape, matching the F-number with an optical system having a non-circular shape will make the diameter larger than the height of the optical system having a non-circular shape. .

〔Example〕
Examples of the imaging optical system of the present invention are shown below. The symbols used in each example are as follows.
f: Focal length of the entire imaging optical system F: F number 2Y: Diagonal length of imaging surface of imaging device R: Radius of curvature D: Distance between upper surfaces of axis Nd: Refractive index of lens material with respect to d-line νd: Abbe number OSx of lens material : Optical surface diameter OSy in the width direction (or longitudinal direction) of the lens : Optical surface diameter in the height direction (or lateral direction) of the lens

ただし、
Ａｉ：ｉ次の非球面係数
Ｒ ：曲率半径
Ｋ ：円錐定数 In each example, a surface with an asterisk (*) after each surface number has an aspherical shape. , and the height in the direction perpendicular to the optical axis AX is represented by the following "Equation 1".

however,
Ai: i-th order aspheric coefficient R: radius of curvature K: conic constant

(Example 1)
The overall specifications of the imaging optical system of Example 1 are shown below.
f=12.00(mm)
F=2.8
2Y=5.3(mm)
LL=8.00(mm)
TTL=13.19(mm)

Data for the lens surfaces of Example 1 are shown in Table 1 below. In addition, in Table 1 and the like below, infinity is represented as "INF", and aperture stop is represented as "ST".
[Table 1]
Surf.NR(mm) D(mm) Nd νd OSx(mm) OSy(mm)
1(ST)INF -0.44 4.50 3.60
2* 3.644 1.76 1.54470 56.2 4.90 3.81
3* 20.443 0.05 4.62 3.69
4* 5.116 0.89 1.63470 23.9 4.50 3.64
5* 2.420 0.61 3.90 3.23
6* 5.333 1.38 1.54470 56.2 4.03 3.31
7* 9.097 0.97 4.02 3.20
8* -3.210 1.46 1.63470 23.9 4.09 3.21
9* -3.966 0.05 4.99 3.72
10* 4.386 0.83 1.54470 56.2 5.40 3.81
11* 5.408 5.25 3.66

The aspheric coefficients of the lens surfaces of Example 1 are shown in Table 2 below. In the following (including lens data in tables), powers of 10 (eg, 2.5×10 ⁻⁰² ) are represented by E (eg, 2.5E-02).
[Table 2]
2nd side
K=0.14051E+00, A3=0.33440E-03, A4=-0.14206E-02,
A5=0.81777E-03, A6=-0.37615E-03, A7=0.37986E-04,
A8=0.00000E+00
3rd side
K=0.49511E+02, A3=0.32581E-02, A4=0.17573E-02,
A5=-0.13966E-02, A6=0.44786E-04, A7=0.74697E-04,
A8=0.00000E+00
4th side
K=-0.11440E+01, A3=0.43708E-02, A4=-0.27774E-02,
A5=0.22491E-03, A6=0.14067E-03, A7=-0.21092E-04,
A8=0.00000E+00
5th side
K=-0.18645E+01, A3=0.32231E-02, A4=0.51637E-02,
A5=0.31578E-02, A6=0.21179E-03, A7=0.52540E-04,
A8=0.00000E+00
6th side
K=-0.59755E+01, A3=0.11748E-02, A4=0.22838E-02,
A5=0.10858E-02, A6=0.10413E-03, A7=0.37953E-03,
A8=-0.10779E-03
7th side
K=0.18102E+02, A3=0.23936E-03, A4=-0.74157E-02,
A5=0.13688E-02, A6=0.63209E-03, A7=-0.39317E-03,
A8=0.00000E+00
8th side
K=-0.38556E+01, A3=-0.14811E-02, A4=-0.71135E-02,
A5=0.30806E-03, A6=0.13718E-02, A7=-0.80066E-03,
A8=0.00000E+00
9th side
K=0.91775E+00, A3=-0.29230E-02, A4=0.13884E-01,
A5=-0.58928E-03, A6=-0.72003E-03, A7=-0.89032E-04,
A8=0.56625E-04
10th side
K=-0.24382E-01, A3=0.37457E-02, A4=-0.83241E-02,
A5=0.27108E-02, A6=0.48212E-03, A7=-0.25279E-03,
A8=0.00000E+00
11th side
K=-0.18328E+02, A3=0.89366E-02, A4=-0.52535E-02,
A5=0.11161E-02, A6=0.18117E-02, A7=-0.48885E-03,
A8=0.00000E+00

6A to 6C are diagrams for explaining the imaging optical system 10A and the like of Example 1. FIG. FIG. 6A is a cross-sectional view of the lenses of the imaging optical system 10A in the width direction x. FIG. 6B is a cross-sectional view of the lenses of the imaging optical system 10A in the height direction y. FIG. 6C is a plan view of the aperture 13 of the aperture stop ST, and a cross-sectional view at the position of the aperture 13 of the imaging optical system 10A. Illustrations of bending elements, light shielding members, etc. are omitted (the same applies to the following embodiments). The imaging optical system 10A includes, in order from the object side, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, and a fifth lens L5. An aperture stop ST is arranged on the object side of the first lens L1. The aperture 13 of the aperture stop ST and the optical surfaces of the first to fifth lenses L1 to L5 have non-circular shapes.

(Example 2)
The overall specifications of the imaging optical system of Example 2 are shown below.
f=14.03(mm)
F=3.3
2Y=4 (mm)
LL=6.68(mm)
TTL=12.70(mm)

Data for the lens surfaces of Example 2 are shown in Table 3 below.
[Table 3]
Surf.NR(mm) D(mm) Nd νd OSx(mm) OSy(mm)
1(ST)INF -0.40 4.30 4.00
2* 3.408 1.72 1.54470 56.2 4.63 4.26
3* -119.353 0.12 4.45 4.06
4* 29.900 0.96 1.63470 23.9 4.36 3.98
5* 3.728 0.39 3.81 3.50
6* 5.103 0.97 1.54470 56.2 3.82 3.49
7* 4.529 1.06 3.80 3.47
8* 13.630 0.49 1.63470 23.9 3.86 3.47
9* -17.918 0.45 3.85 3.45
10* -7.418 0.53 1.54470 56.2 3.80 3.38
11* 322.263 3.46 3.93 3.43
12INF 0.21 1.51630 64.1 4.00 3.60
13INF 4.00 3.60

The aspheric coefficients of the lens surfaces of Example 2 are shown in Table 4 below.
[Table 4]
2nd side
K=-0.81987E-01, A4=0.52448E-04, A6=0.15456E-04,
A8=0.49313E-05, A10=-0.75105E-06
3rd side
K=-0.80000E+02, A4=0.17368E-02, A6=0.11447E-03,
A8=-0.82653E-05, A10=0.81473E-06
4th side
K=0.53507E+02, A4=-0.99947E-03, A6=0.18554E-03,
A8=0.33217E-04, A10=-0.12425E-05
5th side
K=-0.15776E+01, A4=0.33690E-02, A6=0.91561E-04,
A8=0.55270E-04, A10=0.32801E-04
6th side
K=-0.20979E+01, A4=0.16168E-02, A6=-0.11973E-03,
A8=-0.27050E-04, A10=0.70555E-05
7th side
K=0.34853E+01, A4=-0.61989E-02, A6=0.12271E-03,
A8=-0.11390E-03, A10=-0.35124E-04
8th side
K=0.37381E+02, A4=-0.25804E-02, A6=0.42636E-04,
A8=-0.16786E-03, A10=0.13261E-04
9th side
K=0.65334E+02, A4=0.26252E-02, A6=0.54334E-04,
A8=-0.12455E-03, A10=0.43036E-04
10th side
K=0.89807E+01, A4=-0.93595E-02, A6=0.37463E-03,
A8=0.59061E-04, A10=0.13911E-04
11th side
K=0.80000E+02, A4=-0.10728E-01, A6=0.66780E-03,
A8=0.19875E-05, A10=-0.43844E-05

7A to 7C are diagrams for explaining the imaging optical system 10B and the like of Example 2. FIG. FIG. 7A is a cross-sectional view of the lenses of the imaging optical system 10B in the width direction x. FIG. 7B is a cross-sectional view of the lenses of the imaging optical system 10B in the height direction y. FIG. 7C is a plan view of the aperture 13 of the aperture stop ST. Note that the bending element, the light shielding member, and the like are omitted from the drawing. The imaging optical system 10B includes, in order from the object side, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, and a fifth lens L5. An aperture stop ST is arranged on the object side of the first lens L1. A parallel plate F is arranged between the light exit surface of the fifth lens L5 and the imaging surface (image surface) I. The parallel flat plate F is assumed to be an optical low-pass filter, an IR cut filter, a sealing glass of a solid-state imaging device, or the like (the same applies to the following embodiments). The aperture 13 of the aperture stop ST and the optical surfaces of the first to fifth lenses L1 to L5 have non-circular shapes.

(Example 3)
The overall specifications of the imaging optical system of Example 3 are shown below.
f = 20.80 (mm)
F=3.6
2Y=4 (mm)
LL=12.55(mm)
TTL=17.50(mm)

Data for the lens surfaces of Example 3 are shown in Table 5 below.
[Table 5]
Surf.NR(mm) D(mm) Nd νd OSx(mm) OSy(mm)
1(ST)INF -0.50 6.40 4.54
2* 4.858 2.41 1.54470 56.2 6.73 4.61
3* -30.917 0.23 6.40 4.27
4* 125.546 1.44 1.63470 23.9 6.11 4.13
5* 6.307 1.14 5.12 3.62
6* 8.711 1.42 1.54470 56.2 4.94 3.45
7* 6.053 3.21 4.52 3.14
8* 90.426 0.50 1.63470 23.9 4.23 2.85
9* -12.231 0.70 4.25 2.83
10* -5.031 1.49 1.54470 56.2 4.05 2.67
11* -26.426 4.00 4.21 2.70
12INF 0.21 1.51630 64.1 4.40 3.60
13INF 4.40 3.60

The aspheric coefficients of the lens surfaces of Example 3 are shown in Table 6 below.
[Table 6]
2nd side
K=-0.57301E-01, A4=0.33846E-04, A6=0.49638E-05,
A8=0.48466E-06, A10=0.22545E-08
3rd side
K=-0.45968E+02, A4=0.62247E-03, A6=0.29760E-04,
A8=-0.72790E-06, A10=-0.78220E-07
4th side
K=0.80000E+02, A4=-0.86463E-04, A6=0.47287E-04,
A8=0.37355E-05, A10=-0.35381E-06
5th side
K=-0.15724E+01, A4=0.10381E-02, A6=0.63967E-04,
A8=0.22762E-04, A10=0.78722E-06
6th side
K=-0.42601E+01, A4=0.56481E-04, A6=-0.62544E-04,
A8=0.27859E-05, A10=-0.22007E-06
7th side
K=0.40145E+01, A4=-0.26737E-02, A6=-0.13682E-03,
A8=-0.59560E-04, A10=-0.16643E-05
8th side
K=-0.26470E+01, A4=-0.14811E-03, A6=-0.10715E-03,
A8=-0.88273E-04, A10=-0.19739E-04
9th side
K=0.12736E+02, A4=0.20803E-03, A6=-0.71746E-04,
A8=-0.51391E-04, A10=-0.25692E-04
10th side
K=0.26415E+01, A4=0.38799E-03, A6=0.41321E-03,
A8=0.88190E-04, A10=-0.21288E-04
11th side
K=-0.66280E+02, A4=-0.19927E-02, A6=0.22422E-03,
A8=-0.14021E-04, A10=-0.18579E-05

8A to 8C are diagrams for explaining the imaging optical system 10C and the like of Example 3. FIG. FIG. 8A is a cross-sectional view of the lenses of the imaging optical system 10C in the width direction x. FIG. 8B is a cross-sectional view of the lens of the imaging optical system 10C in the height direction y. FIG. 8C is a plan view of the aperture 13 of the aperture stop ST. The imaging optical system 10C includes, in order from the object side, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, and a fifth lens L5. An aperture stop ST is arranged on the object side of the first lens L1. A parallel plate F is arranged between the light exit surface of the fifth lens L5 and the imaging surface (image surface) I. The aperture 13 of the aperture stop ST and the optical surfaces of the first to fifth lenses L1 to L5 have non-circular shapes.

(Example 4)
The overall specifications of the imaging optical system of Example 4 are shown below.
f = 16.90 (mm)
F=3.7
2Y=5 (mm)
LL=9.43(mm)
TTL=13.00(mm)

Data for the lens surfaces of Example 4 are shown in Table 7 below.
[Table 7]
Surf.NR(mm) D(mm) Nd νd OSx(mm) OSy(mm)
1(ST)INF -0.45 4.80 3.80
2* 3.996 2.12 1.54470 56.2 5.11 4.01
3* -11.920 0.31 4.93 3.82
4* -53.190 1.20 1.63470 23.9 4.64 3.62
5* 5.341 1.05 4.08 3.23
6* 5.721 0.86 1.54470 56.2 3.92 3.09
7* 3.716 2.67 3.63 3.06
8* -11.640 0.51 1.63470 23.9 3.50 3.08
9* -3.756 0.32 3.60 3.16
10* -4.748 0.40 1.54470 56.2 4.11 3.09
11* 7.323 1.16 4.34 3.16
12INF 0.21 1.51630 64.1 5.00 4.00
13INF 5.00 4.00

The aspheric coefficients of the lens surfaces of Example 4 are shown in Table 8 below.
[Table 8]
2nd side
K=-0.11896E+00, A4=-0.16400E-04, A6=-0.10730E-04,
A8=0.32966E-05, A10=-0.38585E-06
3rd side
K=-0.29301E+02, A4=0.48017E-03, A6=0.11479E-04,
A8=-0.45798E-05, A10=0.49828E-06
4th side
K=0.77573E+02, A4=-0.83077E-03, A6=0.17620E-05,
A8=0.15061E-04, A10=0.58614E-06
5th side
K=-0.36489E+01, A4=0.37401E-03, A6=0.21608E-04,
A8=0.55233E-05, A10=0.12575E-04
6th side
K=-0.57597E+00, A4=0.46073E-03, A6=-0.37119E-04,
A8=-0.81743E-06, A10=-0.17927E-04
7th side
K=0.21276E+01, A4=-0.37758E-02, A6=-0.66670E-04,
A8=0.21843E-03, A10=-0.18131E-03
8th side
K=0.42818E+02, A4=-0.94434E-02, A6=0.87857E-04,
A8=-0.69294E-03, A10=0.24833E-03
9th side
K=0.16950E+00 A4=0.80164E-02, A6=-0.50472E-02,
A8=0.54725E-03, A10=0.59017E-04
10th side
K=0.22301E+01, A4=-0.12632E-01, A6=0.82113E-02,
A8=-0.24302E-02, A10=0.42126E-03
11th side
K=-0.36532E+02, A4=-0.27985E-01, A6=0.10467E-01,
A8=-0.22180E-02, A10=0.17917E-03

9A to 9C are diagrams for explaining the imaging optical system 10D and the like of Example 4. FIG. FIG. 9A is a cross-sectional view of the lenses of the imaging optical system 10D in the width direction x. FIG. 9B is a cross-sectional view of the lenses of the imaging optical system 10D in the height direction y. FIG. 9C is a plan view of the aperture 13 of the aperture stop ST. The imaging optical system 10D includes, in order from the object side, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, and a fifth lens L5. An aperture stop ST is arranged on the object side of the first lens L1. A parallel plate F is arranged between the light exit surface of the fifth lens L5 and the imaging surface (image surface) I. The aperture 13 of the aperture stop ST and the optical surfaces of the first to fifth lenses L1 to L5 have non-circular shapes.

Table 9 below summarizes the values of Examples 1 to 4 corresponding to each conditional expression (1) to (3).
[Table 9]

Although the present invention has been described with reference to the embodiments and examples, the present invention is not limited to the above-described embodiments and the like. For example, in the above embodiment, all of the plurality of lenses constituting the imaging optical system 10 are assumed to have a non-circular shape. good.

Further, in the above embodiment, the imaging optical system 10 is provided with the bending element PR, but the bending element PR may not be provided. In this case, the incident direction of light is along the major axis direction z of the imaging optical system 10 .

AX... Optical axis F... Parallel plate I... Imaging surface L1 to L5... Lens PR... Bending element SH1 to SH3 Light blocking member 10, 10A, 10B, 10C... Imaging optical system 30... Camera module 40 ...Lens unit 41...Frame member 50...Sensor unit 51...Imaging device 60...Processing unit 100...Imaging device 300...Mobile communication terminal

Claims (8)

Equipped with an aperture diaphragm and a plurality of lenses,
an aperture of the aperture stop and an optical surface of at least one lens among the plurality of lenses have a non-circular shape;
the aperture stop is arranged on the object side of the lens closest to the object side among the plurality of lenses, and is provided independently from the lens closest to the object side;
The lens has a pair of linear edges extending in parallel, the direction parallel to the pair of parallel edges is the width direction, and the direction perpendicular to the pair of parallel edges is the height direction,
An imaging optical system , wherein the aperture stop and all of the plurality of lenses having a non-circular shape satisfy the following conditional expression.
0.5<Dyape/Dxape<1.0 (1)
Dylens/Dyepd<1.2 (2)
however,
Dxape: length in the width direction of the aperture of the aperture stop Dyape: length in the height direction of the aperture of the aperture stop Dylens: an arbitrary natural number up to the total number of lenses having the non-circular shape where i is the optical surface diameter in the height direction of the i-th lens having the non-circular shape Dyepd: the entrance pupil diameter in the height direction of the entire plurality of lenses 2. The imaging optical system according to claim 1, wherein the following conditional expression is satisfied.
0.3<LL/TTL<0.8 (3)
however,
LL: distance on the optical axis from the most object-side lens surface to the image-side lens surface among the plurality of lenses TTL: the optical axis from the most object-side lens surface to the image-side focal point among the plurality of lenses distance above 3. The imaging optical system according to claim 1, further comprising a bending element between the object and the image plane position. Among the aperture diaphragm and the plurality of lenses, the lens having a non-circular shape has a shape cut along a line orthogonal to the height direction of the lens so that the length of the circular lens in the height direction is shortened. The imaging optical system according to any one of claims 1 to 3 , characterized in that: 5. The imaging optical system according to any one of claims 1 to 4 , wherein optical surfaces of all the lenses of the plurality of lenses have a non-circular shape. 6. The imaging optical system according to any one of claims 1 to 5 , wherein the plurality of lenses are composed of five or more lenses. A light shielding member arranged between an object and an image plane position, and a frame member holding the plurality of lenses,
The imaging optical system according to any one of claims 1 to 6 , wherein the opening of the light shielding member and the opening of the frame member have non-circular shapes. An imaging apparatus comprising: the imaging optical system according to any one of claims 1 to 7 ; and an imaging device for detecting an image obtained from the imaging optical system.

Images