WO2020014918A1

WO2020014918A1 - Imaging lens, imaging apparatus, and mobile equipment

Info

Publication number: WO2020014918A1
Application number: PCT/CN2018/096247
Authority: WO
Inventors: Tateoka SUSUMU; Masahiko Koyanagi
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2018-07-19
Filing date: 2018-07-19
Publication date: 2020-01-23

Abstract

An imaging lens includes a first lens (L1) having positive refractive power and a convex surface (S1a) on an objective side, a second lens (L2) having negative refractive power, a third lens (L3) having positive refractive power and a convex surface (S3b) on an imaging side, a fourth lens (L4) having positive refractive power and a convex surface (S4a) on the objective side, a fifth lens (L5) having positive refractive power and a convex surface (S5a) on the objective side, a sixth lens (L6) having a convex surface (S6a) on the objective side, and a seventh lens (L7) having a convex surface (S7a) on the objective side. The first lens (L1), the second lens (L2), the third lens (L3), the fourth lens (L4), the fifth lens (L5), the sixth lens (L6) and the seventh lens (L7) are arranged in order from the objective side to the imaging side. At least one of the sixth lens (L6) and the seventh lens (L7) is an aspherical lens.

Description

IMAGING LENS, IMAGING APPARATUS, AND MOBILE EQUIPMENT

Technical Field

The present disclosure relates to an imaging lens, imaging apparatus, and mobile equipment.

Background Art

Recently, miniaturization of an image sensor such as a CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor) and increasing the quantity of pixels in the image sensor are advancing.

The miniaturization of the image sensor contributes to downsizing mobile equipment equipped with a camera capability, such as a smartphone, a mobile phone, a tablet and a drive recorder. The miniaturization of the image sensor also contributes to downsizing imaging apparatuses, such as a Web camera, an action camera, a monitoring camera, and a compact digital camera.

Increasing the quantity of pixels in the image sensor results in shorter pixel pitches. Thus, the increasing the quantity of pixels imposes higher resolution on the imaging lens. The resolution of the imaging lens depends on a F-number which is an indication of brightness. Smaller F-number may provide higher resolution. However, the smaller F-number may make aberration stand out, which may result in degradation of the quality of captured images. Therefore, a technique of using a plurality of lenses to correct the aberration is applied to the imaging lenses.

Summary of the present disclosure

Embodiments of the present disclosure provide an imaging lens, imaging apparatus, and mobile equipment , so as to provide a smaller F-number lens with less aberration.

To achieve the foregoing objective, the following technical solutions are used in the embodiments of the present disclosure.

A first aspect of an embodiment provides the following imaging lens.

The imaging lens according to the first aspect includes a first lens having positive refractive power and a convex surface on an objective side; a second lens having negative refractive power; a third lens having positive refractive power and a convex surface on an imaging side; a fourth lens having positive refractive power and a convex surface on the objective side; a fifth lens having positive refractive power and a convex surface on the objective side; a sixth lens having a convex surface on the objective side; and a seventh lens having a convex surface on the objective side. The first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens and the seventh lens are arranged in order from the objective side to the imaging side. At least one of the sixth lens and the seventh lens is an aspherical lens.

According to the first aspect, a downsized imaging lens having a large aperture may be provided. For example, a high-performance imaging lens such as a lens whose F-number is within 0.95-1.2 may be provided. Seven-lens configuration of the imaging lens is advantageous to correcting the aberration with good balance in comparison with a conventional six-or fewer-lens configuration. Furthermore, the aspherical lens of the imaging lens may correct aberration in a short optical path.

In a first possible implementation form of the imaging lens according to the first aspect, the sixth lens and the seventh lens may be aspherical lenses having a same shape. According to the first possible implementation form, the two-aspherical lens configuration of the imaging lens may further correct the aberration in the short optical path. In addition, the sixth lens and the seventh lens may be constituted by a same type of lens, so that production costs for the imaging lens may be reduced.

In a second possible implementation form of the imaging lens according to the first aspect, the fourth lens and the fifth lens may have a same shape, a surface of the third lens on the objective side may have a same shape as surfaces of the fourth lens and the fifth lens on the imaging side at least in a vicinity of an optical axis, the surface of the third lens on the imaging side may have a same shape as surfaces of the fourth lens and the fifth lens on the objective side at least in the vicinity of the optical axis, and a thickness of the third lens may be same as thicknesses of the fourth lens and the fifth lens along the optical axis. According to the second possible implementation form, the third lens, the fourth lens and the fifth lens may be constituted by a same type of lens, so that production costs for the imaging lens may be reduced.

In a third possible implementation form of the imaging lens according to the first aspect, the second lens may have a concave surface on the objective side and a concave surface on the imaging side, the third lens may have a concave surface on the objective side, and each of the fourth lens and the fifth lens may have a concave surface on the imaging side. According to the third possible implementation form, the imaging side of the fourth lens and the objective side of the fifth lens may be set closer to each other, and the imaging side of the fifth lens and the objective side of the sixth lens may be set closer to each other, so that an optical lens length of the imaging lens may be shortened. In addition, aberration such as chromatic aberration and spherical aberration may be corrected by the second lens and the third lens.

A second aspect of an embodiment provides the following imaging apparatus.

The imaging apparatus according to the second aspect includes an imaging lens, an imaging sensor, processing circuitry, and a memory. The imaging lens includes a first lens having positive refractive power and a convex surface on an objective side; a second lens having negative refractive power; a third lens having positive refractive power and a convex surface on an imaging side; a fourth lens having positive refractive power and a convex surface on the objective side; a fifth lens having positive refractive power and a convex surface on the objective side; a sixth lens having a convex surface on the objective side; and a seventh lens having a convex surface on the objective side. The first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens and the seventh lens are arranged in order from the objective side to the imaging side. At least one of the sixth lens and the seventh lens is an aspherical lens. The imaging sensor is configured to generate a signal from light passed through the imaging lens. The processing circuitry is configured to generate image data based on the signal, and stores the image data in the memory. In some examples, the processing circuitry may be implemented via processing unit (s) . Processing unit (s) may include application-specific integrated circuit (ASIC) logic, graphics processor (s) , general purpose processor (s) , or the like. In some examples, the processing circuitry may be implemented via hardware, imaging dedicated hardware, or the like.

According to the second aspect, a compact imaging apparatus equipped with a downsized imaging lens having a large aperture may be provided. For example, a compact imaging apparatus which is equipped with a high-performance imaging lens such as a lens whose F-number is within 0.95-1.2 and is capable of acquiring high-quality captured images may be implemented.

A third aspect of an embodiment provides the following mobile equipment.

The mobile equipment according to the third aspect includes an imaging lens, an imaging sensor, processing circuitry and a display device. The imaging lens includes a first lens having positive refractive power and a convex surface on an objective side; a second lens having negative refractive power; a third lens having positive refractive power and a convex surface on an imaging side; a fourth lens having positive refractive power and a convex surface on the objective side; a fifth lens having positive refractive power and a convex surface on the objective side; a sixth lens having a convex surface on the objective side; and a seventh lens having a convex surface on the objective side. The first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens and the seventh lens are arranged in order from the objective side to the imaging side. At least one of the sixth lens and the seventh lens is an aspherical lens. The imaging sensor is configured to generate a signal from light passed through the imaging lens. The processing circuitry is configured to generate image data based on the signal. The display device is configured to display the image data. In some examples, the processing circuitry may be implemented via processing unit (s) . Processing unit (s) may include application-specific integrated circuit (ASIC) logic, graphics processor (s) , general purpose processor (s) , or the like. In some examples, the processing circuitry may be implemented via hardware, imaging dedicated hardware, or the like.

According to the third aspect, compact mobile equipment equipped with a downsized imaging lens having a large aperture may be provided. For example, compact mobile equipment which is equipped with a high-performance imaging lens such as a lens whose F-number is within 0.95-1.2 and is capable of acquiring high-quality captured images may be implemented.

For the purpose of clarity, any one of the foregoing embodiments may be combined with any one or more of the other foregoing embodiments to create a new embodiment within the scope of the present disclosure.

These and other features will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings and claims.

Brief Description of Drawings

To describe the technical solutions according to embodiments more clearly, the following concisely describes the accompanying drawings required for describing the embodiments. Apparently, these accompanying drawings depict merely some of possible embodiments. A person of ordinary skill in the art may still derive other drawings, without creative efforts, from these accompanying drawings, in which:

[Fig. 1] Fig. 1 is a configurational diagram showing an example of an imaging lens according to a first embodiment;

[Fig. 2] Fig. 2 is a table showing examples of conditions for focus lengths of individual lenses constituting the imaging lens according to the first embodiment, and Abbe-number related parameters of the lenses;

[Fig. 3] Fig. 3 is a table showing lens parameters of the individual lenses constituting the imaging lens according to the first embodiment;

[Fig. 4] Fig. 4 is an MTF (Modular Transfer Function) chart showing focusing performance of the imaging lens according to the first embodiment;

[Fig. 5] Fig. 5 is a graph showing a field curvature characteristic of the imaging lens according to the first embodiment;

[Fig. 6] Fig. 6 is a graph showing a distortion characteristic of the imaging lens according to the first embodiment;

[Fig. 7] Fig. 7 is a table showing examples of conditions for focus lengths of individual lenses constituting an imaging lens according to a modification of the first embodiment, and Abbe-number related parameters of the lenses;

[Fig. 8] Fig. 8 is a table showing lens parameters of the individual lenses constituting the imaging lens according to the modification of the first embodiment;

[Fig. 9] Fig. 9 is a configurational diagram showing an example of an imaging lens according to a second embodiment;

[Fig. 10] Fig. 10 is a table showing examples of conditions for focus lengths of individual lenses constituting the imaging lens according to the second embodiment, and Abbe-number related parameters of the lenses;

[Fig. 11] Fig. 11 is a table showing lens parameters of the individual lenses constituting the imaging lens according to the second embodiment;

[Fig. 12] Fig. 12 is an MTF chart showing focusing performance of the imaging lens according to the second embodiment;

[Fig. 13] Fig. 13 is a graph showing a field curvature characteristic of the imaging lens according to the second embodiment;

[Fig. 14] Fig. 14 is a graph showing a distortion characteristic of the imaging lens according to the second embodiment;

[Fig. 15] Fig. 1 is a configurational diagram showing an example of an imaging lens according to a third embodiment;

[Fig. 16] Fig. 16 is a table showing examples of conditions for focus lengths of individual lenses constituting the imaging lens according to the third embodiment, and Abbe-number related parameters of the lenses;

[Fig. 17] Fig. 17 is a table showing lens parameters of the individual lenses constituting the imaging lens according to the third embodiment;

[Fig. 18] Fig. 18 is an MTF chart showing focusing performance of the imaging lens according to the third embodiment;

[Fig. 19] Fig. 19 is a graph showing a field curvature characteristic of the imaging lens according to the third embodiment;

[Fig. 20] Fig. 20 is a graph showing a distortion characteristic of the imaging lens according to the third embodiment;

[Fig. 21] Fig. 21 is a block diagram showing a hardware configurational example of an imaging apparatus which may be equipped with each of the imaging lenses according to the first to third embodiments; and

[Fig. 22] Fig. 22 is a block diagram showing a hardware configurational example of mobile equipment which may be equipped with each of the imaging lenses according to the first to third embodiments.

Description of Embodiments

The following describes technical solutions of the embodiments, referring to the accompanying drawings. Apparently, the embodiments described below are not all but just some of embodiments relating to the present disclosure. It is to be noted that all other embodiments which may be derived by a person skilled in the art based on the embodiments described below without creative efforts shall fall within the protection scope of the present disclosure.

The following describes configurational examples of imaging lenses according to the first embodiment, the second embodiment and the third embodiment, and a property of these imaging lenses in order, and lastly describes configurational examples of an imaging apparatus and mobile equipment which may be equipped with any one of those imaging lenses.

First Embodiment

The first embodiment will be described below.

With reference to Fig. 1, an imaging lens according to the first embodiment will be described. Fig. 1 is a configurational diagram showing an example of the imaging lens according to the first embodiment. The imaging lens 11 shown in Fig. 1 is an example of the imaging lens according to the first embodiment. The configuration of the imaging lens 11 corresponds to conditional examples in Fig. 2 and lens parameters in Fig. 3, both of which will be described later.

In Fig. 1, symbol "AX" denotes an optical axis, symbol "ST" denotes an aperture stop, and symbol "IMG" denotes an imaging surface of the imaging lens 11. An image sensor, such as a CCD or CMOS, is disposed at a position of the imaging surface IMG. Symbols "L1" , "L2" , "L3" , "L4" , "L5" , "L6" and "L7" represent lenses. Symbol "IR" denotes an optical member such as an infrared cutting filter and a cover glass for protection.

As shown in Fig. 1, the imaging lens 11 includes seven lenses (lenses L1, L2, L3, L4, L5, L6, and L7) . The lenses L1, L2, L3, L4, L5, L6, and L7 are arranged in order from an objective side (left side in Fig. 1) to an imaging side (right side in Fig. 1) . The lens L1 is positioned closest to the objective side, and the lens L7 is positioned closest to the imaging side.

The aperture stop ST may be disposed on the objective side of the lens L1. As a modification, the aperture stop ST may be disposed on the objective side of the lens L2.

The configurational diagram of Fig. 1 schematically shows the imaging lens 11 seen from a direction perpendicular to the optical axis AX. The surfaces or the like of the lenses that appear transparent are also indicated by solid lines.

As shown in Fig. 1, an objective-side surface S1a of the lens L1 has a convex shape on the objective side. An imaging-side surface S1b of the lens L1 has a shape determined so as to achieve a pre-determined optical property. For example, the imaging-side surface S1b of the lens L1 may have a convex shape on the imaging side. The shapes of the surfaces S1a and S1b provide the lens L1 with positive refractive power.

An objective-side surface S2a of the lens L2 has a concave shape on the objective side. An imaging-side surface S2b of the lens L2 has a concave shape on the imaging side. That is, the lens L2 is a biconcave lens. The shapes of the surfaces S2a and S2b provide the lens L2 with negative refractive power.

An imaging-side surface S3b of the lens L3 has a convex shape on the imaging side. An objective-side surface S3a of the lens L3 has a shape determined so as to achieve a pre-determined optical property. For example, the objective-side surface S3a of the lens L3 may have a concave shape on the objective side. In this case, the lens L3 has a meniscus shape. The shapes of the surfaces S3a and S3b provide the lens L3 with positive refractive power.

An objective-side surface S4a of the lens L4 has a convex shape on the objective side. An imaging-side surface S4b of the lens L4 has a shape determined so as to achieve a pre-determined optical property. For example, the imaging-side surface S4b of the lens L4 may have a concave shape on the imaging side. In this case, the lens L4 has a meniscus shape. The shapes of the surfaces S4a and S4b provide the lens L4 with positive refractive power.

An objective-side surface S5a of the lens L5 has a convex shape on the objective side. An imaging-side surface S5b of the lens L5 has a shape determined so as to achieve a pre-determined optical property. For example, the imaging-side surface S5b of the lens L5 may have a concave shape on the imaging side. In this case, the lens L5 has a meniscus shape. The shapes of the surfaces S5a and S5b provide the lens L5 with positive refractive power.

The lens L5 may have the same shape as the lens L4. In this case, the lenses L4 and L5 may be constituted by a same type of lens, so that production costs for the imaging lens 11 may be reduced. In addition, production sensitivity of the imaging lens 11 may be lowered because such configuration may reduce a fluctuation of the image surface which may be originated from misalignment of the lenses at the time of manufacture.

The lens L6 is an aspherical lens. An objective-side surface S6a of the lens L6 has a convex shape on the objective side in vicinity of the optical axis. An imaging-side surface S6b of the lens L6 has a shape determined so as to achieve a pre-determined optical property. The lens L6 has refractive power (positive or negative refractive power) corresponding to the shapes of the objective-side surface S6a and the imaging-side surface S6b.

For example, the objective-side surface S6a may be an aspherical surface having a convex shape in the vicinity of the optical axis, and a concave shape at a peripheral portion. Further, the imaging-side surface S6b may be an aspherical surface having a concave shape in the vicinity of the optical axis, and a convex shape at the peripheral portion. Configuring at least one of the surfaces S6a and S6b to an aspherical surface may allow an aberration such as a field curvature aberration to be corrected within a wide range from the center portion of the imaging surface IMG to the peripheral portion.

The lens L7 is an aspherical lens. An objective-side surface S7a of the lens L7 has a convex shape on the objective side in the vicinity of the optical axis. An imaging-side surface S7b of the lens L7 has a shape determined so as to achieve a pre-determined optical property. The lens L7 has refractive power (positive or negative refractive power) corresponding to the shapes of the objective-side surface S7a and the imaging-side surface S7b.

For example, the objective-side surface S7a may be an aspherical surface having a convex shape in the vicinity of the optical axis, and a concave shape at the peripheral portion. Further, the imaging-side surface S7b may be an aspherical surface having a concave shape in the vicinity of the optical axis, and a convex shape at the peripheral portion. Configuring at least one of the surfaces S7a and S7b to an aspherical surface may allow an aberration such as the field curvature aberration to be corrected within a wide range from the center portion of the imaging surface IMG to the peripheral portion.

The lens L7 may have the same shape as the lens L6. In this case, the lenses L6 and L7 may be constituted by a same type of lens, so that the production costs may be reduced. In addition, the production sensitivity of the imaging lens 11 may be lowered. The use of two aspherical lenses as in the example of Fig. 1 may correct an aberration in a short optical path.

When the surfaces S4b and S5b have concave shapes on the imaging side, the concave surface S4b and the convex surface S5a face each other, and the concave surface S5b and the convex surface S6a face each other. Such a lens structure contributes to shortening an inter-lens distance among the lenses L4, L5 and L6. Shortening the inter-lens distance contributes to shortening an entire lens length of the imaging lens 11.

Lines BL1, BL2, BL3 and BL4 represent an optical path of light coming from the objective side. As shown in Fig. 1, adaptation of the above-described structure of the imaging lens 11 causes the optical paths BL1 passing through the imaging lens 11 to reach a single specific point on the imaging surface IMG with a high accuracy. The optical paths BL2, BL3 and BL4 also reach different single specific points on the imaging surface IMG, respectively. In the example of Fig. 1, a high focusing accuracy may be obtained in the optical paths BL3 and BL4 that reach near the optical axis of the imaging surface IMG as well as in the optical paths BL1 and BL2 that reach the peripheral portion.

With reference to Fig. 2 now, examples of conditions for parameters that define the optical property of the individual lenses included in the imaging lens 11 are described. Fig. 2 is a table showing examples of conditions for parameters relating to a focus length and an Abbe-number of each lens constituting the imaging lens according to the first embodiment.

Fig. 2 shows, as a condition A, a condition relating to an upper limit and a lower limit of a parameter which is given in terms of a ratio of focus lengths. Fig. 2 also shows, as a condition B, a range of the Abbe number set for each lens. As a modification, numerical values given within parentheses in the columns corresponding to the upper limits and the lower limits in the condition A may be used. The numerical values given within the parentheses may provide an excellent optical property.

In Fig. 2, f represents a focus length in the imaging lens 11. f1, f2, f3, f4, f5, and f6 respectively represent focus lengths of the lenses L1, L2, L3, L4, L5, and L6. νd1, νd2, νd3, νd4, νd5, νd6, and νd7 respectively represent Abbe numbers of the lenses L1, L2, L3, L4, L5, L6, and L7.

When the imaging lens 11 meets the condition A in Fig. 2, f/f2 may take a value included in a range from 0.00 which is a lower limit to 1.10 which is an upper limit. When f/f2 is less than the upper limit, an axial chromatic aberration may be corrected. To enhance the correction effect, the upper limit of f/f2 may be set to 1.00. When f/f2 falls below the lower limit, a spherical aberration and coma aberration may be corrected. When f/f2 meets conditions for the upper limit and the lower limit, an optical path length in the imaging lens 11 may be shortened.

When the imaging lens 11 meets the condition A in Fig. 2, f/f3 may take a value included in a range from -1.35 which is a lower limit to -0.66 which is an upper limit. When f/f3 is less than the upper limit, the spherical aberration may be corrected. When f/f3 falls below the lower limit, an effect to weaken refractive power is obtained. In addition, the production sensitivity of the imaging lens 11 may be lowered.

When the imaging lens 11 meets the condition A in Fig. 2, f/f5 may take a value included in a range from -0.70 which is a lower limit to 0.35 which is an upper limit. When f/f5 is less than the upper limit, the optical path length may be shortened. When f/f5 falls below the lower limit, at least one of the coma aberration and astigmatism may be corrected.

When the imaging lens 11 meets the condition A in Fig. 2, f/f6 may take a value included in a range from -1.20 which is a lower limit to 0.20 which is an upper limit. When f/f6 meets at least one of the condition for the upper limit and the condition for the lower limit, the optical path length may be shortened. To enhance the optical-path length shortening effect, the lower limit of f/f6 may be set to -1.10 and the upper limit of f/f6 may be set to 0.10.

When the imaging lens 11 meets the condition A in Fig. 2, f2/f3 may take a value included in a range from -0.66 which is a lower limit to -0.10 which is an upper limit. When f2/f3 is less than the upper limit, the production sensitivity of the imaging lens 11 may be lowered. When f2/f3 falls below the lower limit, the spherical aberration and coma aberration may be corrected. When conditions for the upper limit and the lower limit of f2/f3 are met, the optical path length may be shortened.

When the imaging lens 11 meets the condition A in Fig. 2, f2/f1 may take a value included in a range from -2.50 which is a lower limit to -1.00 which is an upper limit. When f2/f1 is less than the upper limit, the spherical aberration and coma aberration may be corrected. When f2/f1 falls below the lower limit, the production sensitivity of the imaging lens 11 may be lowered. In addition, when conditions for the upper limit and the lower limit of f2/f1 are met, the optical path length may be shortened.

When the imaging lens 11 meets the condition A in Fig. 2, f5/f6 may take a value included in a range from 0.50 which is a lower limit to 0.80 which is an upper limit. When f5/f6 is less than the upper limit, the optical path length may be shortened. When f5/f6 falls below the lower limit, at least one of the coma aberration and astigmatism may be corrected.

When the imaging lens 11 meets the condition B in Fig. 2, the Abbe number νd1 may take a value greater than 19.3. Further, the Abbe number νd2 may take a value greater than 57.0, the Abbe number νd3 may take a value less than 30.0, and the Abbe number νd4 may take a value greater than 19.3. Also, the Abbe number νd5 may take a value greater than 20.0, the Abbe number νd6 may take a value greater than 19.3, and the Abbe number νd7 may take a value greater than 19.3.

When conditions for the Abbe numbers νd1, νd2, νd4, νd6 and νd7 in the condition B are met, the axial chromatic aberration and a chromatic aberration of magnification may be corrected in an excellent balance.

Referring now to Fig. 3, lens parameters of the individual lenses included in the imaging lens 11 are described. Fig. 3 is a table showing the lens parameters of the individual lenses constituting the imaging lens according to the first embodiment. Lens structural diagram shown in Fig. 1 is a schematic diagram of lens structure that is specified by the lens parameters shown in Fig. 3.

Column of "Lens" in the table shown in Fig. 3 shows symbols of corresponding lenses. Further, in the table, a column of "Surf. " shows symbols of corresponding lens surfaces, and a column of "Radius" shows radiuses of curvature of the corresponding lens surfaces. Moreover, in the table, a column of "Thick. " shows thicknesses of the individual lenses along the optical axis, a column of "Conic" shows conic constants of the corresponding lens surfaces, and the column of Aspherical Coefficients shows aspherical coefficients of corresponding orders.

Shape of an aspherical lens is given by an equation for an aspherical shape shown in the following equation Q, where Z indicates a depth of the aspherical surface, Y indicates a distance (height) from the optical axis to a lens surface, R indicates a paraxial radius of curvature, and K indicates a conic constant. C ₄, C ₆, C ₈, C ₁₀, C ₁₂, C ₁₄, and C ₁₆ respectively indicate aspherical coefficients of 4th order, 6th order, 8th order, 10th order, 12th order, 14th order, and 16th order.

Z= (Y ²/R) / [1- {1- (1+K) (Y ²/R ²) } ^1/2] +C ₄Y ⁴+C ₆Y ⁶+C ₈Y ⁸+C ₁₀Y ¹⁰+C ₁₂Y ¹²+C ₁₄Y ¹⁴+C ₁₆Y ¹⁶ (Q)

In the example of Fig. 3, the lenses L1, L6, and L7 are aspherical lenses, and the lenses L2, L3, L4, and L5 are spherical lenses. As a modification, the lens L1 may be a spherical lens. At least one of the lenses L1, L2, L3, L4, L5, L6, and L7 may be a resin lens. When each of the aspherical lenses is constituted by the resin lens which is easy to process, for example, production costs for the imaging lens 11 may be reduced.

In the table shown in Fig. 3, the lens parameters relating to the lenses L4 and L5 indicate that the lenses L4 and L5 have the same shape at least in the vicinity of the optical axis. That is, the thicknesses of the lenses L4 and L5 take the same value (0.62) , the radiuses of curvature of the surface S4b of the lens L4 and the surface S5b of the lens L5 take the same value (40.90) , and the radiuses of curvature of the surface S4a of the lens L4 and the surface S5a of the lens L5 take the same value (4.56) .

Further, in the table shown in Fig. 3, the lens parameters for the lenses L3 and L4 indicate that the surface S3a of the lens L3 and the surface S4b of the lens L4 have the same shape at least in the vicinity of the optical axis. The lens parameters for the lenses L3 and L4 also indicate that the surface S3b of the lens L3 and the surface S4a of the lens L4 have the same shape at least in the vicinity of the optical axis. Since the thicknesses of the lenses L3 and L4 take the same value (0.62) , the lens L3 has the same shape as the lens L4 at least in the vicinity of the optical axis.

When the lens parameters in Fig. 3 are used, lenses having the same shape (lenses of the same type which are produced in the same production process) may be used as the lenses L3, L4 and L5. The use of lenses of the same type may reduce production costs for the imaging lens 11. In addition, the production sensitivity of the imaging lens 11 may be lowered.

The lens parameters relating to the lenses L6 and L7 indicate that the lenses L6 and L7 have the same shape at least in the vicinity of the optical axis. That is, the thicknesses of the lenses L6 and L7 take the same value (0.95) , the radiuses of curvature of the surface S6b of the lens L6 and the surface S7b of the lens L7 take the same value (11.13) , and the radiuses of curvature of the surface S6a of the lens L6 and the surface S7a of the lens L7 take the same value (-31.10) .

When the lens parameters in Fig. 3 are used, lenses having the same shape (lenses of the same type) may be used as the lenses L6 and L7. The use of lenses of the same type may reduce production costs for the imaging lens 11. In addition, the production sensitivity of the imaging lens 11 may be lowered.

Figs. 4 to 6 show results of simulation on the imaging lens 11 that meet the conditional examples in Fig. 2 and has the lens parameters in Fig. 3, where F-number is 1.0, the focus length of the imaging lens is 2.65 (mm) , a half viewing angle ω is 35 (deg. ) , and a reference wavelength is the wavelength of the d-line (wavelength of 587.6 nm) .

Fig. 4 is an MTF chart showing focusing performance of the imaging lens according to the first embodiment. Fig. 5 is a graph showing field curvature characteristics of the imaging lens according to the first embodiment. Fig. 6 is a graph showing distortion characteristics of the imaging lens according to the first embodiment.

In Fig. 4, the horizontal axis represents a spatial frequency, and the longitudinal axis represents the MTF. MTF is an index for evaluating focusing performance of a lens, which represents, in terms of spatial frequency characteristics, how faithfully contrast of a subject may be reproduced. To evaluate an influence of the astigmatism, a plurality of MTF curves according to angles from a sagittal direction and angles from a tangential direction (meridional direction) are shown in Fig. 4. In Figs. 5 and 6, the longitudinal axis represents the image height Y (mm) .

As shown in Figs. 4 to 6, the lens structure of the first embodiment optimizes power distribution of the individual lenses in the imaging lens 11, thus implementing the high-performance imaging lens.

The lens structure shown in Figs. 1 to 3 may be modified. As a modification, the imaging lens 11 may be designed according to configuration of conditional examples shown in Fig. 7 and lens parameters shown in Fig. 8. Fig. 7 is a table showing examples of conditions for focus lengths of individual lenses constituting an imaging lens according to a modification of the first embodiment, and Abbe-number related parameters of the lenses. Fig. 8 is a table showing lens parameters of the individual lenses constituting the imaging lens according to the modification of the first embodiment.

Various aberrations may be corrected by configuring the focus lengths of the individual lenses according to, for example, condition A in Fig. 7. In addition, the chromatic aberration may be corrected by configuring the Abbe numbers of the individual lenses in such a way as to fall within a range shown in Example 1 of condition B in Fig. 7. As a modification, the Abbe numbers of the individual lenses may be configured in such a way as to fall within a range shown in Example 2 of the condition B. Example 2 of the condition B may provide an excellent effect of correction. Configuration examples shown in Fig. 7 show one example of the focus lengths and Abbe numbers of the individual lenses that meet the conditions A and B.

Although the surface S2a of the lens L2 has a shape close to a plane in the example of Fig. 8, this configuration may still allow the lens L2 to have the negative refractive power.

AR (Anti-reflection) coating may be applied to the lens surface. The AR coating is a technique of forming a coat material (e.g., a material having a refractive index of about 1.2 to 1.3) with a thickness equivalent to 1/4 of the wavelength on the lens surface to cancel out light which is reflected at the lens surface. Single-layer or multi-layer AR coating may be applied to the imaging lens 11. Furthermore, the AR coating may be applied not to all of the lens surfaces, but to the surfaces S4a, S4b, S6a, and S6b. The AR coating may suppress light loss inside the imaging lens 11.

Second Embodiment

The second embodiment will be described next. Details of redundant descriptions of the first embodiment will not be described below.

With reference to Fig. 9, an imaging lens according to the second embodiment will be described. Fig. 9 is a configurational diagram showing an example of the imaging lens according to the second embodiment. Imaging lens 11a shown in Fig. 9 is an example of the imaging lens according to the second embodiment. The configuration of the imaging lens 11a corresponds to conditional examples in Fig. 10 and lens parameters in Fig. 11, both of which will be described later.

The imaging lens 11a according to the second embodiment, like the imaging lens 11 according to the first embodiment, includes seven lenses (lenses L1, L2, L3, L4, L5, L6, and L7) . The lenses L1, L2, L3, L4, L5, L6, and L7 are arranged in order from an objective side (left side in Fig. 9) to an imaging side (right side in Fig. 9) . The lens L1 is positioned closest to the objective side, and the lens L7 is positioned closest to the imaging side. Aperture stop ST may be disposed on the objective side of the lens L1. As a modification, the aperture stop ST may be disposed on the objective side of the lens L2.

Shapes of the lenses L1, L2, L3, L4, L5, L6, and L7 are as shown in Fig. 9. In the imaging lens 11a, the lenses L1 and L2 have negative refractive power. The lenses L3 and L4 have positive refractive power. The lenses L6 and L7 are aspherical lenses. The shapes of the lenses L6 and L7 are determined so as to achieve a pre-determined optical property. For example, the lenses L6 and L7 may have convex surfaces on the objective side and the imaging side in the vicinity of the optical axis. Further, the lenses L6 and L7 may have the same shape.

The individual lenses of the imaging lens 11a meet the conditional examples shown in Fig. 10, and the lens parameters shown in Fig. 11 define the shapes of the lenses.

Fig. 10 is a table showing examples of conditions for focus lengths of individual lenses constituting the imaging lens according to the second embodiment, and Abbe-number related parameters of the lenses. Fig. 11 is a table showing lens parameters of the individual lenses constituting the imaging lens according to the second embodiment.

Various aberrations may be corrected by configuring focus lengths of the individual lenses according to condition A in Fig. 10. In addition, the chromatic aberration may be corrected by configuring Abbe numbers of the individual lenses in such a way as to fall within a range shown in Example 1 of condition B in Fig. 10. As a modification, the Abbe numbers of the individual lenses may be configured in such a way as to fall within a range shown in Example 2 of the condition B. Example 2 of the condition B may provide an excellent effect of correction. Configuration examples shown at the bottom of the table show one example of the focus lengths and Abbe numbers of the individual lenses that meet the conditions A and B.

As shown in Fig. 11, the lenses L4 and L5 have the same shape at least in the vicinity of the optical axis. The lens L3 has a shape which is the shape of the lens L4 on the objective side and on the imaging side inverted. Therefore, the lenses L3, L4, and L5 may be constituted by lenses of the same type. Likewise, the lenses L6 and L7 have the same shape at least in the vicinity of the optical axis. Therefore, the lenses L6 and L7 may be constituted by lenses of the same type. Making a plurality of lenses using lenses of the same type may reduce the production costs for the imaging lens 11a. In addition, the production sensitivity of the imaging lens 11 may be lowered.

Figs. 12 to 14 show results of simulation on the imaging lens 11a that meet the conditional examples in Fig. 10 and has the lens parameters in Fig. 11, where F-number is 1.0, the focus length of the imaging lens 11a is 2.65 (mm) , a half viewing angle ω is 35 (deg. ) , and a reference wavelength is the wavelength of the d-line (wavelength of 587.6 nm) . Fig. 12 is an MTF chart showing focusing performance of the imaging lens according to the second embodiment. Fig. 13 is a graph showing field curvature characteristics of the imaging lens according to the second embodiment. Fig. 14 is a graph showing the distortion characteristics of the imaging lens according to the second embodiment.

As shown in Figs. 12 to 14, lens structure of the second embodiment optimizes power distribution of the individual lenses in the imaging lens 11a, thus implementing the high-performance imaging lens.

Third Embodiment

The third embodiment will be described next. Details of redundant descriptions of the first embodiment will not be described below.

With reference to Fig. 15, an imaging lens according to the third embodiment will be described. Fig. 15 is a configurational diagram showing an example of the imaging lens according to the third embodiment. An imaging lens 11b shown in Fig. 15 is an example of the imaging lens according to the third embodiment. Configuration of the imaging lens 11b corresponds to conditional examples in Fig. 16 and lens parameters in Fig. 17, both of which will be described later.

The imaging lens 11b according to the third embodiment, like the imaging lens 11 according to the first embodiment, includes seven lenses (lenses L1, L2, L3, L4, L5, L6, and L7) . The lenses L1, L2, L3, L4, L5, L6, and L7 are arranged in order from an objective side (left side in Fig. 15) to an imaging side (right side in Fig. 15) . The lens L1 is positioned closest to the objective side, and the lens L7 is positioned closest to the imaging side. Aperture stop ST may be disposed on the objective side of the lens L1. As a modification, the aperture stop ST may be disposed on the objective side of the lens L2.

Shapes of the lenses L1, L2, L3, L4, L5, L6, and L7 are as shown in Fig. 15. In the imaging lens 11b, the lenses L1, L2, L3, L4, and L5 have positive refractive power. The lenses L6 and L7 are aspherical lenses. The shapes of the lenses L6 and L7 are determined so as to achieve a pre-determined optical property. For example, the lenses L6 and L7 may have convex surfaces on the objective side and the imaging side in the vicinity of the optical axis. Further, the lenses L6 and L7 may have the same shape.

The individual lenses of the imaging lens 11b meet the conditional examples shown in Fig. 16, and the lens parameters shown in Fig. 17 define the shapes of the lenses.

Fig. 16 is a table showing examples of conditions for focus lengths of individual lenses constituting the imaging lens according to the third embodiment, and Abbe-number related parameters of the lenses. Fig. 17 is a table showing lens parameters of the individual lenses constituting the imaging lens according to the third embodiment.

Various aberrations may be corrected by configuring focus lengths of the individual lenses according to condition A in Fig. 16. In addition, the chromatic aberration may be corrected by configuring the Abbe numbers of the individual lenses in such a way as to fall within a range shown in Example 1 of condition B in Fig. 16. As a modification, the Abbe numbers of the individual lenses may be configured in such a way as to fall within a range shown in Example 2 of the condition B. Example 2 of the condition B may provide an excellent effect of correction. Configuration examples shown at the bottom of the table show one example of the focus lengths and Abbe numbers of the individual lenses that meet the conditions A and B.

As shown in Fig. 17, the lenses L4 and L5 have the same shape at least in the vicinity of the optical axis. The lens L3 has a shape which is the shape of the lens L4 on the objective side and on the imaging side inverted. Therefore, the lenses L3, L4, and L5 may be constituted by lenses of the same type. Likewise, the lenses L6 and L7 have the same shape at least in the vicinity of the optical axis. Therefore, the lenses L6 and L7 may be constituted by lenses of the same type. Making a plurality of lenses using lenses of the same type may reduce the production costs for the imaging lens 11a. In addition, the production sensitivity of the imaging lens 11 may be lowered.

Figs. 18 to 20 show results of simulation on the imaging lens 11b that meet the conditional examples in Fig. 16 and has the lens parameters in Fig. 17, where F-number is 1.0, the focus length of the imaging lens 11b is 2.65 (mm) , a half viewing angle ω is 35 (deg. ) , and a reference wavelength is the wavelength of the d-line (wavelength of 587.6 nm) . Fig. 18 is an MTF chart showing focusing performance of the imaging lens according to the third embodiment. Fig. 19 is a graph showing field curvature characteristics of the imaging lens according to the third embodiment. Fig. 20 is a graph showing distortion characteristics of the imaging lens according to the third embodiment.

As shown in Figs. 18 to 20, lens structure of the third embodiment optimizes power distribution of the individual lenses in the imaging lens 11b, thus implementing the high-performance imaging lens.

Implementation to Imaging Apparatus

Referring to Fig. 21, the following describes an imaging apparatus 10A which may be equipped with each of the above-described

imaging lenses

11, 11a and 11b. The imaging apparatus 10A may be an apparatus such as a Web camera, an action camera, a monitoring camera, or a compact digital camera.

Fig. 21 is a block diagram showing a hardware configurational example of an imaging apparatus which may be equipped with each of the imaging lenses according to the first to third embodiments. Although the imaging apparatus 10A equipped with the imaging lens 11 is described below for the sake of convenience, the same description may be applied to the cases where the imaging apparatus 10A is equipped with the

imaging lens

11a or 11b.

As shown in Fig. 21, the imaging apparatus 10A includes an imaging lens 11, an imaging sensor 12A, and processing circuitry 13A. The imaging apparatus 10A may have a plurality of imaging lenses including at least one imaging lens 11. The imaging apparatus 10A may further include other elements. For example, the imaging apparatus 10A may include a memory 14A.

The imaging sensor 12A includes an image sensor such as a CCD or CMOS.

For example, the image sensor of the imaging sensor 12A is disposed at the position of the imaging surface IMG. The image sensor has a plurality of pixels. For example, the image sensor includes pixels which generate an electrical signal according to intensity of a red light component, pixels which generate an electrical signal according to intensity of a blue light component, and pixels which generate an electrical signal according to intensity of a green light component. As a modification, the image sensor may be an another image sensor for monochromatic imaging including a plurality of pixels which generate an electrical signal according to intensity of light.

The imaging sensor 12A includes an AD (Analog to Digital) converter that converts an analog electrical signal generated by the image sensor to a digital imaging signal. The imaging signal generated by the AD converter is output to the processing circuitry 13A. The imaging sensor 12A may include an element other than the image sensor and the AD converter.

In some examples, the processing circuitry 13A may be implemented via processing unit (s) . Processing unit (s) may include application-specific integrated circuit (ASIC) logic, graphics processor (s) , general purpose processor (s) , or the like. In some examples, the processing circuitry 13A may be implemented via hardware, imaging dedicated hardware, or the like. The memory 14A is a storage device such as a ROM (Read Only Memory) , RAM (Random Access Memory) , HDD (Hard Disk Drive) , SSD (Solid State Drive) or flash memory.

The processing circuitry 13A controls the operation of the imaging apparatus 10A. The processing circuitry 13A processes the imaging signal output from the imaging sensor 12A.

The processing circuitry 13A may store the imaging signal into the memory 14A. The processing circuitry 13A may also generate image data from the imaging signal. For example, the processing circuitry 13A may perform compression, decoding and the like to generate image data such as a JPEG (Joint Photographic Experts Group) image from RAW data which is one example of the imaging signal. The processing circuitry 13A may also store the image data into the memory 14A.

In addition, the processing circuitry 13A may read out a program from a storage medium (for example, a magnetic storage medium, optical disc, magneto optical disk, or semiconductor memory) connected to the imaging apparatus 10A and store the program into the memory 14A, and may control the operation of the imaging apparatus 10A according to the program read out from the memory 14A. The program for controlling the operation of the imaging apparatus 10A may be stored in advance in the memory 14A, or may be downloaded over a network such as a LAN (Local Area Network) or WAN (Wide Area Network) .

Implementation to Mobile Equipment

Referring to Fig. 22, the following describes mobile equipment 10B which may be equipped with at least one of the above-described

imaging lenses

11, 11a and 11b. The mobile equipment 10B may be a device such as a smartphone, a mobile phone, a tablet, or a drive recorder.

Fig. 22 is a block diagram showing a hardware configurational example of mobile equipment which may be equipped with each of the imaging lenses according to the first to third embodiments. Although the mobile equipment 10B equipped with the imaging lens 11 is described below for the sake of convenience, the same description may be applied to the cases where the mobile equipment 10B is equipped with the

imaging lens

11a or 11b.

As shown in Fig. 22, the mobile equipment 10B includes an imaging lens 11, an imaging sensor 12B, processing circuitry 13B, a display device 15B, and a communication interface 16B. The mobile equipment 10B may further include other elements, or may have some elements removed. For example, the mobile equipment 10B may include a memory 14B. In some examples, the processing circuitry 13B may be implemented via processing unit (s) . Processing unit (s) may include application-specific integrated circuit (ASIC) logic, graphics processor (s) , general purpose processor (s) , or the like. In some examples, the processing circuitry 13B may be implemented via hardware, imaging dedicated hardware, or the like.

The mobile equipment 10B may have a plurality of imaging lenses including at least one imaging lens 11. The imaging sensor 12B may be the same hardware as the above-described imaging sensor 12A. The processing circuitry 13B may be the same hardware as the above-described processing circuitry 13A. The memory 14B may be the same hardware as the above-described memory 14A.

The imaging sensor 12B includes an image sensor such as a CCD or CMOS, and an AD converter that converts an analog electrical signal output from the image sensor to a digital imaging signal. The processing circuitry 13B is a processing device such as a CPU, DSP, ASIC, or FPGA. The memory 14B is a storage device such as a ROM, RAM, HDD, SSD or flash memory.

The processing circuitry 13B controls the operation of the imaging apparatus 10B. The processing circuitry 13B processes the imaging signal output from the imaging sensor 12B.

The processing circuitry 13B may store the imaging signal into the memory 14B. The processing circuitry 13B may also generate image data from the imaging signal. For example, the processing circuitry 13B may perform compression, decoding and the like to generate image data such as a JPEG image from RAW data which is one example of the imaging signal. The processing circuitry 13B may also store the image data into the memory 14B.

In addition, the processing circuitry 13B may read out a program from a storage medium (for example, a magnetic storage medium, optical disc, magneto optical disk, or semiconductor memory) connected to the mobile equipment 10B and store the program into the memory 14B, and may control the operation of the mobile equipment 10B according to the program read out from the memory 14B. The program for controlling the operation of the mobile equipment 10B may be stored in advance in the memory 14B, or may be downloaded over a network such as a LAN or WAN.

The display device 15B is a device for display, such as an LCD (Liquid Crystal Display) or ELD (Electro-Luminescence Display) . For example, the processing circuitry 13B may display image data on the display device 15B directly or via a GPU (Graphic Processing Unit) of the mobile equipment 10B.

The communication interface 16B serves to connect to a network such as a LAN, WAN or cell phone network. The network may be a wireless network or may be a wired network. The processing circuitry 13B may transmit image data to the network via the communication interface 16B, and may download a program over the network via the communication interface 16B.

Implementation of the above-described

imaging lens

11, 11a or 11b into the imaging apparatus 10A and the mobile equipment 10B may make the imaging apparatus 10A and the mobile equipment 10B compact. In addition, the camera capability of the imaging apparatus 10A and the mobile equipment 10B may be enhanced. Also, the production costs for the imaging apparatus 10A and the mobile equipment 10B may be reduced.

The following gives additional notes on several aspects according to embodiments of the present disclosure and implementations of the aspects.

A first aspect of an embodiment provides the following imaging lens.

According to the first aspect, a downsized imaging lens having a large aperture is provided. For example, a high-performance imaging lens having a F-number of 0.95-1.2 is provided.

According to a first implementation according to the first aspect, the sixth lens and the seventh lens may be aspherical lenses having the same shape.

According to the first implementation according to the first aspect, the sixth lens and the seventh lens may be constituted by a same type of lens, so that the production costs may be reduced. In addition, production sensitivity that is sensitivity to production errors may be lowered in the imaging lens.

According to the first implement according to the first aspect, for example, the sixth lens and the seventh lens may be constituted by using an aspherical lens whose objective-side surface has a convex shape in the vicinity of the optical axis, and a concave shape at the peripheral portion. Therefore, an aberration such as a field curvature aberration may be corrected within a wide range from the center portion of the imaging surface to the peripheral portion. In addition, the use of two aspherical lenses may allow an aberration to be corrected in a short optical path.

According to a second implementation according to the first aspect, the fourth lens and the fifth lens may have the same shape, the objective-side surface of the third lens may have the same shape as the imaging-side surfaces of the fourth lens and the fifth lens at least in the vicinity of the optical axis, the imaging-side surface of the third lens may have the same shape as the objective-side surfaces of the fourth lens and the fifth lens at least in the vicinity of the optical axis, and the thickness of the third lens may be the same as the thicknesses of the fourth lens and the fifth lens along the optical axis.

According to the second implementation according to the first aspect, the third lens, the fourth lens and the fifth lens may be constituted by a same type of lens, so that the production costs may be reduced. In addition, the production sensitivity of the imaging lens may be lowered.

According to a third implementation according to the first aspect, the second lens may have a concave surface on the objective side and a concave surface on the imaging side, the third lens may have a concave surface on the objective side, and each of the fourth lens and the fifth lens may have a concave surface on the imaging side.

According to the third implementation according to the first aspect, the imaging side of the fourth lens and the objective side of the fifth lens may be set closer to each other, and the imaging side of the fifth lens and the objective side of the sixth lens may be set closer to each other, so that the entire lens length may be shortened. In addition, according to the third implementation according to the first aspect, aberrations such as the chromatic aberration and spherical aberration may be corrected by the second lens and the third lens.

In a fourth implement according to the first aspect, at least one of the following conditional expressions (1) to (7) may be met.

0.30<f/f3<0.50 (1)

0.30<f/f5<0.50 (2)

-0.55<f/f2<1.10 (3)

0.20<f/f6<0.50 (4)

-0.66<f2/f3<-0.10 (5)

-2.60<f2/f1<-1.00 (6)

0.50<f5/f6<0.80 (7)

where f is a focus length of the imaging lens, f1 is a focus length of the first lens, f2 is a focus length of the second lens, f3 is a focus length of the third lens, f4 is a focus length of the fourth lens, f5 is a focus length of the fifth lens, and f6 is a focus length of the sixth lens.

According to the fourth implementation according to the first aspect, at least one of correction of the chromatic aberration, correction of the spherical aberration, correction of the coma aberration, correction of the astigmatism, lowering of the production sensitivity, shortening of the entire lens length, and shortening of the optical path length may be achieved.

When the condition for the upper limit in the conditional expression (1) is met, for example, the spherical aberration may be corrected. When the condition for the lower limit in the conditional expression (1) is met, refractive power may be weakened, thus lowering the production sensitivity of the imaging lens.

When the condition for the upper limit in the conditional expression (2) is met, the optical path length may be shortened. When the condition for the lower limit in the conditional expression (2) is met, at least one of the coma aberration and the astigmatism may be corrected.

When the condition for the upper limit in the conditional expression (3) is met, the axial chromatic aberration may be corrected. When the condition for the lower limit in the conditional expression (3) is met, the spherical aberration and the coma aberration may be corrected. Further, as the conditional expression (3) is met, the optical path length may be shortened. When at least one of the condition for the upper limit and the condition for the lower limit in the conditional expression (4) is met, the optical path length may be shortened.

When the condition for the upper limit in the conditional expression (5) is met, the production sensitivity of the imaging lens may be lowered. When the condition for the lower limit in the conditional expression (5) is met, the spherical aberration and the coma aberration may be corrected. Further, as the conditional expression (5) is met, the optical path length may be shortened.

When the condition for the upper limit in the conditional expression (6) is met, the spherical aberration and the coma aberration may be corrected. When the condition for the lower limit in the conditional expression (6) is met, the production sensitivity of the imaging lens may be lowered. Further, as the conditional expression (3) is met, the optical path length may be shortened.

When the condition for the upper limit in the conditional expression (7) is met, the optical path length may be shortened. When the condition for the lower limit in the conditional expression (7) is met, at least one of the coma aberration and the astigmatism may be corrected. When the condition for the lower limit in the conditional expression (6) is met, the production sensitivity may be lowered. Further, as the conditional expression (3) is met, the optical path length may be shortened.

In a fifth implement according to the first aspect, at least one of the following conditional expressions (8) to (14) may be met.

νd1>56.0 (8)

νd2>56.0 (9)

νd4>19.3 (10)

νd6>19.3 (11)

νd7>19.3 (12)

νd3>30.0 (13)

νd5>20.0 (14)

where νd1 is an Abbe number of the first lens, νd2 is an Abbe number of the second lens, νd3 is an Abbe number of the third lens, νd4 is an Abbe number of the fourth lens, νd5 is an Abbe number of the fifth lens, νd6 is an Abbe number of the sixth lens, and νd7 is an Abbe number of the seventh lens.

According to the fifth implement according to the first aspect, the chromatic aberration is corrected. When the conditional expressions (8) to (12) are met, for example, the axial chromatic aberration and chromatic aberration of magnification may be corrected in an excellent balance. When the conditional expressions (13) and (14) are met, the axial chromatic aberration may be corrected.

A second aspect of an embodiment provides the following imaging apparatus.

The imaging apparatus according to the second aspect includes an imaging lens, an imaging sensor, processing circuitry, and a memory. The imaging lens includes a first lens having positive refractive power and a convex surface on an objective side; a second lens having negative refractive power; a third lens having positive refractive power and a convex surface on an imaging side; a fourth lens having positive refractive power and a convex surface on the objective side; a fifth lens having positive refractive power and a convex surface on the objective side; a sixth lens having a convex surface on the objective side; and a seventh lens having a convex surface on the objective side. The first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens and the seventh lens are arranged in order from the objective side to the imaging side. At least one of the sixth lens and the seventh lens is an aspherical lens. The imaging sensor generates a signal from light passed through the imaging lens. The processing circuitry generates image data based on the signal, and stores the image data in the memory.

According to the second aspect, a compact imaging apparatus equipped with a downsized imaging lens having a large aperture is provided. For example, a compact imaging apparatus which is equipped with a high-performance imaging lens such as a lens whose F-number is within 0.95-1.2 and is capable of acquiring high-quality captured images, may be implemented.

As one implementation according to the second aspect, an imaging apparatus equipped with an imaging lens according to at least one of the first to fifth implementations according to the second aspect may be provided. According to one implementation according to the second aspect, at least one of various aberrations, such as the spherical aberration, astigmatism, coma aberration, field curvature and chromatic aberration, may be corrected. In addition, one implementation according to the second aspect may provide effects such as shortening the entire lens length, shortening the optical path length, reducing the production cost, and lowering the production sensitivity.

A third aspect of an embodiment provides the following mobile equipment.

The mobile equipment according to the third aspect includes an imaging lens, an imaging sensor, processing circuitry, and a display device. The imaging lens includes a first lens having positive refractive power and a convex surface on an objective side; a second lens having negative refractive power; a third lens having positive refractive power and a convex surface on an imaging side; a fourth lens having positive refractive power and a convex surface on the objective side; a fifth lens having positive refractive power and a convex surface on the objective side; a sixth lens having a convex surface on the objective side; and a seventh lens having a convex surface on the objective side. The first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens and the seventh lens are arranged in order from the objective side to the imaging side. At least one of the sixth lens and the seventh lens is an aspherical lens. The imaging sensor generates a signal from light passed through the imaging lens. The processing circuitry generates image data based on the signal, and displays the image data on the display device. In some examples, the processing circuitry may be implemented via processing unit (s) . Processing unit (s) may include application-specific integrated circuit (ASIC) logic, graphics processor (s) , general purpose processor (s) , or the like. In some examples, the processing circuitry may be implemented via hardware, imaging dedicated hardware, or the like.

According to the third aspect, compact mobile equipment equipped with a downsized imaging lens having a large aperture is provided. For example, compact mobile equipment which is equipped with a high-performance imaging lens such as a lens whose F-number is within 0.95-1.2 and is capable of acquiring high-quality captured images, may be implemented.

As one implementation according to the third aspect, mobile equipment equipped with an imaging lens according to at least one of the first to fifth implementations according to the first aspect may be provided. According to one implementation according to the third aspect, at least one of various aberrations, such as the spherical aberration, astigmatism, coma aberration, field curvature and chromatic aberration, may be corrected. In addition, one implementation according to the third aspect may provide effects such as shortening the entire lens length, shortening the optical path length, reducing the production cost, and lowering the production sensitivity.

The foregoing disclosure merely discloses exemplary embodiments, and is not intended to limit the protection scope of the present invention. It will be appreciated by those skilled in the art that the foregoing embodiments and all or some of other embodiments and modifications which may be derived based on the scope of claims of the present invention will of course fall within the scope of the present invention.

Claims

An imaging lens comprising:

a first lens having positive refractive power and a convex surface on an objective side;

a second lens having negative refractive power;

a third lens having positive refractive power and a convex surface on an imaging side;

a fourth lens having positive refractive power and a convex surface on the objective side;

a fifth lens having positive refractive power and a convex surface on the objective side;

a sixth lens having a convex surface on the objective side; and

a seventh lens having a convex surface on the objective side, wherein:

the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens and the seventh lens are arranged in order from the objective side to the imaging side, and at least one of the sixth lens and the seventh lens is an aspherical lens.
The imaging lens according to claim 1, wherein

the sixth lens and the seventh lens are aspherical lenses having a same shape.
The imaging lens according to claim 1 or 2, wherein

the fourth lens and the fifth lens have a same shape,

a surface of the third lens on the objective side has a same shape as surfaces of the fourth lens and the fifth lens on the imaging side at least in a vicinity of an optical axis,

the surface of the third lens on the imaging side has a same shape as surfaces of the fourth lens and the fifth lens on the objective side at least in the vicinity of the optical axis, and

a thickness of the third lens is same as thicknesses of the fourth lens and the fifth lens along the optical axis.
The imaging lens according to any one of claims 1 to 3, wherein

the second lens has a concave surface on the objective side and a concave surface on the imaging side,

the third lens has a concave surface on the objective side, and

each of the fourth lens and the fifth lens has a concave surface on the imaging side.
The imaging lens according to any one of claims 1 to 4, wherein

a focus length f3 of the third lens and a focus length f of the imaging lens meet a following conditional expression (1) , and/or

a focus length f5 of the fifth lens and the focus length f of the imaging lens meet a following conditional expression (2) , wherein

0.30<f/f3<0.50 (1) ,

0.30<f/f5<0.50 (2) .
The imaging lens according to any one of claims 1 to 5, wherein

a focus length f2 of the second lens and the focus length f of the imaging lens meet a following conditional expression (3) , wherein

-0.55<f/f2<1.10 (3) .
The imaging lens according to any one of claims 1 to 6, wherein

a focus length f6 of the sixth lens and the focus length f of the imaging lens meet a following conditional expression (4) , wherein

0.20<f/f6<0.50 (4) .
The imaging lens according to any one of claims 1 to 7, wherein

a focus length f2 of the second lens and a focus length f3 of the third lens meet a following conditional expression (5) , wherein

-0.66<f2/f3<-0.10 (5) .
The imaging lens according to any one of claims 1 to 8, wherein

a focus length f2 of the second lens and a focus length f1 of the first lens meet a following conditional expression (6) , wherein

-2.60<f2/f1<-1.00 (6) .
The imaging lens according to any one of claims 1 to 9, wherein

a focus length f5 of the fifth lens and a focus length f6 of the sixth lens meet a following conditional expression (7) , wherein

0.50<f5/f6<0.80 (7) .
The imaging lens according to any one of claims 1 to 10, wherein

an Abbe number νd1 of the first lens meets a following conditional expression (8) ,

an Abbe number νd2 of the second lens meets a following conditional expression (9) ,

an Abbe number νd4 of the fourth lens meets a following conditional expression (10) ,

an Abbe number νd6 of the sixth lens meets a following conditional expression (11) , and/or

an Abbe number νd7 of the seventh lens meets a following conditional expression (12) , wherein

νd1>56.0     (8) ,

νd2>56.0     (9) ,

νd4>19.3     (10) ,

νd6>19.3     (11) ,

νd7>19.3     (12) .
The imaging lens according to any one of claims 1 to 11, wherein

an Abbe number νd3 of the third lens meets a following conditional expression (13) , wherein

νd3>30.0 (13) .
The imaging lens according to any one of claims 1 to 12, wherein

an Abbe number νd5 of the fifth lens meets a following conditional expression (14) , wherein

νd5>20.0 (14) .
An imaging apparatus comprising:

an imaging lens, an imaging sensor, and processing circuitry, the imaging lens including:

a first lens having positive refractive power and a convex surface on an objective side;

a second lens having negative refractive power;

a third lens having positive refractive power and a convex surface on an imaging side;

a fourth lens having positive refractive power and a convex surface on the objective side;

a fifth lens having positive refractive power and a convex surface on the objective side;

a sixth lens having a convex surface on the objective side;

a seventh lens having a convex surface on the objective side; and

wherein the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens and the seventh lens are arranged in order from the objective side to the imaging side, and at least one of the sixth lens and the seventh lens is an aspherical lens;

wherein the imaging sensor is configured to generate a signal from light passed through the imaging lens; and

the processing circuitry is configured to generate image data based on the signal.
The imaging apparatus according to claim 14, wherein

the sixth lens and the seventh lens are aspherical lenses having a same shape.
The imaging apparatus according to claim 14 or 15, wherein

the fourth lens and the fifth lens have a same shape,

a surface of the third lens on the objective side has a same shape as surfaces of the fourth lens and the fifth lens on the imaging side at least in a vicinity of an optical axis,

the surface of the third lens on the imaging side has a same shape as surfaces of the fourth lens and the fifth lens on the objective side at least in the vicinity of the optical axis, and

a thickness of the third lens is same as thicknesses of the fourth lens and the fifth lens along the optical axis.
The imaging apparatus according to any one of claims 14 to 16, wherein

the second lens has a concave surface on the objective side and a concave surface on the imaging side,

the third lens has a concave surface on the objective side, and

each of the fourth lens and the fifth lens has a concave surface on the imaging side.
Mobile equipment comprising:

an imaging lens, an imaging sensor, a processing circuitry, and a display device, the imaging lens including:

a first lens having positive refractive power and a convex surface on an objective side;

a second lens having negative refractive power;

a third lens having positive refractive power and a convex surface on an imaging side;

a fourth lens having positive refractive power and a convex surface on the objective side;

a fifth lens having positive refractive power and a convex surface on the objective side;

a sixth lens having a convex surface on the objective side; and

a seventh lens having a convex surface on the objective side, wherein

the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens and the seventh lens are arranged in order from the objective side to the imaging side, and at least one of the sixth lens and the seventh lens is an aspherical lens;

wherein the imaging sensor is configured to generate a signal from light passed through the imaging lens;

the processing circuitry is configured to generate image data based on the signal; and

the display device is configured to display the image data.
The mobile equipment according to claim 18, wherein

the sixth lens and the seventh lens are aspherical lenses having a same shape.
The mobile equipment according to claim 18 or 19, wherein

the fourth lens and the fifth lens have a same shape,

a surface of the third lens on the objective side has a same shape as surfaces of the fourth lens and the fifth lens on the imaging side at least in a vicinity of an optical axis,

the surface of the third lens on the imaging side has a same shape as surfaces of the fourth lens and the fifth lens on the objective side at least in the vicinity of the optical axis, and

a thickness of the third lens is same as thicknesses of the fourth lens and the fifth lens along the optical axis.
The mobile equipment according to any one of claims 18 to 20, wherein

the second lens has a concave surface on the objective side and a concave surface on the imaging side,

the third lens has a concave surface on the objective side, and

each of the fourth lens and the fifth lens has a concave surface on the imaging side.