Image capturing lens, image capturing device, and information processing device

Abstract

To provide an image capturing lens which can be configured to be bright, high-performing, and more compact with a wide angle of view, and to provide an image capturing device and information processing device.SOLUTION: An image capturing lens 100 provided herein comprises first through fourth lenses L1-L4 arranged in order from the object side, and an aperture stop S located on the most object side. The first lens L1 is a positive meniscus lens having a convex surface on the object side. The second lens L2 is a lens with a small thickness deviation ratio having an inflection point on at least one surface. The third lens L3 is a positive lens having a convex surface on the image side and an inflection point in a peripheral portion of the lens. The fourth lens L4 is a negative lens having a concave surface on the image side and an inflection point in a peripheral portion thereof.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to an imaging lens, an imaging device, and an information processing device.

Background Art

[0002] In recent years, imaging devices such as digital still cameras, digital camcorders, and smartphone cameras, which include individual image sensors such as CCD (Charge Coupled Device) and CMOS (Complementary Metal Oxide Semiconductor), and imaging lenses, have become widespread.

[0003] The individual image sensors used in these imaging devices are becoming higher in pixel count. Along with this increase in pixel count of the individual image sensors, higher optical performance is also required for the imaging lenses.

[0004] Also, in recent years, on personal computers (PCs) equipped with imaging devices, video distribution and communication are being carried out via the web. For this reason, the imaging devices are also being miniaturized in consideration of portability. The imaging devices demanded in the market are mainly those that achieve both high performance and miniaturization, and for the imaging lenses, not only high performance but also miniaturization is required. For this reason, imaging lenses that achieve both high performance and miniaturization are known (see, for example, Patent Document 1 and Patent Document 2).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] By the way, in recent years, when delivering or communicating videos through the Web, there has been a demand for an imaging lens that can capture images with a wider angle of view than conventional imaging lenses. For this reason, there has been a demand for an imaging lens that has a wider angle of view, is brighter, has high performance, and is small in size than conventional imaging lenses.

[0007] The present disclosure has been made in view of the above, and an object thereof is to provide an imaging lens, an imaging device, and an information processing device that have a wide angle of view, are bright, have high performance, and are small in size.

Means for Solving the Problems

[0008] In order to solve the above-described problems and achieve the object, an imaging lens according to a first aspect of the present disclosure includes a first lens to a fourth lens arranged in order from the object side, and an aperture stop on the most object side, wherein the first lens is a positive meniscus lens having a convex surface facing the object side, the second lens has an inflection point on at least one surface and is a lens having a small decentration ratio, the third lens is a positive lens having a convex surface facing the image plane side and having an inflection point at the lens peripheral portion, the fourth lens is a negative lens having a concave surface facing the image plane side and having an inflection point at the peripheral portion, and when the focal length of the first lens is f1, the focal length of the fourth lens is f4, and the focal length of the entire optical system is f, conditions (1) and (2) 0.45 < |f / f1| < 0.80 ···(1) 0.25 < |f4 / f1| < 0.50 ···(2) are satisfied.

[0009] Moreover, an imaging device according to a second aspect of the present disclosure includes the above-described imaging lens and an individual imaging element that receives an image formed by the imaging lens and generates an imaging signal.

[0010] Moreover, an information processing device according to a third aspect of the present disclosure includes the above-described imaging device and a display unit that displays an image corresponding to the imaging signal generated by the imaging device.

Advantages of the Invention

[0011] According to the present disclosure, there is an effect that an imaging lens with a wide angle of view, bright, high performance, and small size can be provided.

Brief Description of the Drawings

[0012]

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DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, the imaging lens, imaging device, and information processing device according to the present disclosure will be described with reference to the drawings. Note that the present disclosure is not limited by the following embodiments. Also, each of the drawings referred to in the following description only schematically shows the shape, size, and positional relationship to the extent that the content of the present disclosure can be understood. That is, the present disclosure is not limited only to the shape, size, and positional relationship illustrated in each drawing. Also, the same reference numerals are given to the same parts, and detailed descriptions thereof are omitted.

[0014] [Embodiment] FIG. 1, FIG. 3, FIG. 5, FIG. 7, FIG. 9, FIG. 11, FIG. 13, FIG. 15, FIG. 17, and FIG. 19 are cross-sectional views showing the lens configurations of the imaging lenses of Embodiments 1 to 10, respectively. In each cross-sectional view, the left side is the object side (front), and the right side is the image side (rear).

[0015] The imaging lens 100 of each embodiment includes a first lens L1, a second lens L2, a third lens L3, and a fourth lens L4 arranged in order from the object side to the image side. Further, the imaging lens 100 includes a diaphragm S (STOP) arranged on the object side of the first lens L1.

[0016] In FIGS. 1, 3, 5, 7, 9, 11, 13, 15, 17, and 19, the reference numerals 1 to 9 attached to any of the first lens L1 to the fourth lens L4 and the diaphragm S represent the surfaces of each lens or diaphragm. Hereinafter, these surfaces will be sequentially referred to as surfaces 1 to 9 from the object side to the image side. Surface 1 is the surface of the diaphragm S. Further, in FIGS. 1, 3, 5, 7, 9, 11, 13, 15, 17, and 19, the reference numeral CG represents a transparent parallel plate equivalent to at least one or more of a cover glass of an individual imaging element and various filters. The incident side surface of the transparent parallel plate CG is referred to as surface 10, and the image side surface is referred to as surface 11.

[0017] The imaging lens 100 is arranged with an aperture stop S, and first to fourth lenses L1 to L4 in order from the object side. In the imaging lens 100, the first lens L1 is a positive lens, and the second lens is a lens with positive or negative power. Also, in the imaging lens 100, the third lens is a positive lens and the fourth lens is a negative lens. Furthermore, in the imaging lens 100, the lens on the object side is a positive lens and the lens on the image plane side is a negative lens. In the case of such a lens configuration, the incident angle of light rays tends to be low, and the exit angle of light rays increases with the negative lens of the fourth lens L4, the final lens. However, by appropriately balancing the lens powers, good telecentricity on the image side can be achieved.

[0018] The first lens L1 is a positive meniscus lens with a convex surface facing the object side, and the image plane side may have an inflection point at the lens peripheral portion. Here, the inflection point at the peripheral portion is a region including positions from 60% to 80% from the optical axis toward the outer edge with respect to the aperture diameter of the first lens L1 on the surface 2 side.

[0019] The second lens L2 is configured using a positive or negative lens having at least one inflection point on at least one surface and a small eccentricity ratio, and may have inflection points on both surfaces.

[0020] The third lens L3 is configured using a positive lens with a convex surface facing the image plane side and an inflection point at the lens peripheral portion of the surface on the object side.

[0021] The fourth lens L4 is configured using a negative lens with a concave surface facing the image plane side and an inflection point at the peripheral portion.

[0022] The first lens L1 to the fourth lens L4 configured as described above are all aspherical lenses, each having a characteristic aspherical shape. Furthermore, by making the first lens L1 and the fourth lens L4 have a shape with an inflection point, it is possible to highly correct aberrations in a state where the thickness (total length) in the optical direction of the imaging lens 100 is reduced.

[0023] Regarding the lens material, as shown in the embodiments described later, an optical plastic material or a glass material can be used.

[0024] Figures 2A to 2C, Figures 4A to 4C, Figures 6A to 6C, Figures 8A to 8C, Figures 10A to 10C, Figures 12A to 12C, Figures 14A to 14C, Figures 16A to 16C, Figures 18A to 18C, and Figures 20A to 20C are, respectively, the longitudinal aberration diagrams, MTFs, and distortion grids of the imaging lenses 100 of Embodiments 1 to 10. In the spherical aberration diagram, the spherical aberration amounts for the d-line (yellow: wavelength 587.6 nm), g-line (blue: wavelength 435.8 nm), and C-line (red: 653.3 nm) are shown respectively. In the astigmatism diagram, the solid line S indicates the astigmatism amount on the sagittal image plane, and the dashed line T indicates the astigmatism amount on the tangential image plane. Further, in the distortion diagram, the distortion amount for only the d-line is shown. Also, Angle (deg) indicates the imaging semi-field angle (°). In the MTF, the frequencies are at 1 / 4Ny and 1 / 2Ny. At 1 / 4Ny, the five-dot chain line indicates the MTF of the sagittal image plane, and the thick dashed line indicates the MTF of the tangential image plane. At 1 / 2Ny, the three-dot chain line indicates the MTF of the sagittal image plane, and the thin dashed line indicates the MTF of the tangential image plane. Regarding the distortion grid, the thin line indicates the paraxial (Paraxial FOV) (ideal) grid, and the thick line indicates the actual (Actual FOV) grid.

[0025] Next, the conditions of the imaging lens 100 of each embodiment will be described. When the focal length of the first lens L1 is f1, the focal length of the fourth lens L4 is f4, and the focal length of the entire optical system is f, the imaging lens 100 of each embodiment satisfies the following conditions (1) and (2). 0.45 < |f / f1| < 0.80 ···(1) 0.25 < |f4 / f1| < 0.50 ···(2)

[0026] Condition (1) is a conditional expression regarding the overall focal length of the imaging lens 100 and the lens power of the first lens L1.

[0027] When f / f1 is equal to or less than the lower limit of condition (1), the overall focal length tends to become shorter, which is advantageous for achieving a wider angle of view. However, since the astigmatism tends to be excessive and the distortion also tends to increase, it is difficult to achieve the desired performance. Also, when f / f1 is equal to or greater than the upper limit of condition (1), although the spherical aberration and astigmatism tend to be improved, the angle of view tends to become narrower, so it is not desirable because the desired performance in the embodiments of the present disclosure cannot be achieved. Therefore, by satisfying condition (1), the imaging lens 100 can achieve a balance between shortening (low-profile) and high performance.

[0028] Condition (2) is a conditional expression regarding the positive power of the first lens L1 and the negative power of the fourth lens L4.

[0029] When |f4 / f1| is equal to or less than the lower limit of condition (2), not only does the astigmatism tend to be excessive, but also significant spherical aberration occurs, making it difficult to achieve the desired performance. Also, when |f4 / f1| is equal to or greater than the upper limit of condition (2), the spherical aberration tends to be insufficient, disrupting the balance with the astigmatism and making it difficult to achieve the desired performance.

[0030] That is, by satisfying condition (1) and condition (2), the imaging lens 100 can achieve a balance between spherical aberration and astigmatism, realizing a bright, high-performance, and small (compact) imaging lens 100. Here, "small" means reducing the thickness by shortening the overall length of the imaging lens 100 in the optical axis direction, and reducing the aperture of the imaging lens 100.

[0031] Also, the imaging lens 100 of each embodiment satisfies condition (3) when the refractive index of the material of the first lens L1 with respect to the d-line is N1 and the refractive index of the material of the fourth lens L4 with respect to the d-line is N4. N1 < N4 ···(3)

[0032] Condition (3) is a condition that defines the relationship between the refractive index N1 of the material of the first lens L1 and the refractive index N4 of the material of the fourth lens L4.

[0033] The first lens L1 is a positive lens. Also, the fourth lens L4 is a negative lens. In the disclosure, in order to appropriately correct chromatic aberration and balance miniaturization, the refractive index N1 of the first lens L1 is formed of a material having a refractive index smaller than the refractive index N4 of the fourth lens L4, and by satisfying condition (3), a desired good chromatic aberration can be realized.

[0034] Also, in the imaging lens 100 of each embodiment, the refractive index N1 of the material of the first lens L1 with respect to the d-line satisfies condition (4). 1.49 < N1 < 1.55 ···(4)

[0035] When the refractive index N1 is below the lower limit of condition (4), the optical performance is further improved, but it is not preferable because the cost increases. Also, when the refractive index N1 is above the upper limit of condition (4), the optical performance is affected by chromatic aberration, so it is not preferable. Therefore, by the imaging lens 100 satisfying condition (4), a balance between cost and chromatic aberration can be achieved, and a bright, high-performance, and small (compact) imaging lens 100 can be realized.

[0036] Also, in the imaging lens 100 of each embodiment, the refractive index N5 of the material of the fourth lens L4 with respect to the d-line satisfies condition (5). 1.63 < N4 < 1.67 ···(5)

[0037] When the refractive index N4 is below the lower limit of condition (5), or when the refractive index N4 is above the upper limit of condition (5), the balance of chromatic aberration is disrupted. Considering the balance between cost and chromatic aberration, by satisfying condition (5), a bright, high-performance, and small imaging lens 100 can be realized.

[0038] In addition, when the focal length of the entire optical system (imaging lens 100) is f and the overall length of the optical system (in the longitudinal direction of the imaging lens 100) is OAL, the imaging lens 100 of each embodiment satisfies condition (6). 0.60 < f / OAL < 0.75 ···(6)

[0039] Condition (6) is a condition for balancing the focal length f and the overall length OAL of the entire optical system.

[0040] In the imaging lens 100 of each embodiment, when f / OAL is less than or equal to the lower limit of condition (6), further wide-angleization can be achieved, but the front lens diameter tends to increase, which may lead to an increase in size. Also, when f / OAL is greater than or equal to the upper limit of condition (6), the overall length of the optical system becomes smaller, but it becomes difficult to achieve a wide angle of view. The imaging lens 100 that satisfies condition (6) can achieve miniaturization of size and wide-angleization of the angle of view.

[0041] In addition, when the overall length of the optical system is OAL and the effective diameter of the lens (first lens L1) disposed closest to the object side is EfD1, the imaging lens 100 of each embodiment satisfies condition (7). 2.9 < OAL / EfD1 < 3.6 ···(7)

[0042] Condition (7) is a condition for balancing the overall length of the lens and the front lens diameter of the lens (first lens L1).

[0043] When OAL / EfD1 is less than or equal to the lower limit of condition (7), the optical system is miniaturized (shortened in the optical axis direction), but it becomes difficult to achieve a wide angle of view. When OAL / EfD1 is greater than or equal to the upper limit of condition (7), the performance of the optical system is improved, but it becomes difficult to achieve miniaturization (shortened in the optical axis direction). The imaging lens 100 can achieve miniaturization (shortened in the optical axis direction) and high performance by satisfying condition (7).

[0044] In addition, when the exit pupil position is EXP and the image height is IH, the imaging lens 100 of each embodiment satisfies condition (9). -0.94 < EXP / IH < -0.70 ···(8)

[0045] Condition (8) is a condition for optimizing the incident angle of light rays onto the image plane.

[0046] When EXP / IH is less than or equal to the lower limit of condition (8), the incident angle of light rays tends to be low, but it becomes difficult to shorten the overall length of the optical system and miniaturize it. Also, when EXP / IH is greater than or equal to the upper limit of condition (8), the incident angle of light rays tends to be high. Therefore, by satisfying condition (8), the imaging lens 100 can be miniaturized.

[0047] Also, for the imaging lens 100 of each embodiment, when the focal length of the first lens L1 is f1 and the focal length of the second lens is f2, it satisfies condition (9). 0.01 < |f1 / f2| < 0.40 ···(9)

[0048] Condition (9) is a condition regarding the balance of the focal lengths of the first lens L1 and the second lens L2.

[0049] When |f1 / f2| is less than or equal to the lower limit of condition (9), the lens power of f2 with respect to f1 becomes weak, so spherical aberration and distortion aberration tend to be insufficiently corrected, making it difficult to achieve high performance. Also, when |f1 / f2| is greater than or equal to the upper limit of condition (9), astigmatism tends to become large, which is not desirable. Therefore, by satisfying condition (9), the imaging lens 100 can achieve high performance.

[0050] Also, for the imaging lens 100 of each embodiment, when the focal length of the first lens L1 is f1 and the focal length of the third lens L3 is f3, it satisfies condition (10). 0.25 < f3 / f1 < 0.55 ···(10)

[0051] Condition (10) is a conditional expression regarding the positive power of the first lens L1 and the positive power of the third lens L3.

[0052] When f3 / f1 is less than or equal to the lower limit of condition (10), the astigmatism tends to be excessive, and significant distortion and coma aberrations also occur, making it difficult to achieve the desired performance. Also, when f3 / f1 is greater than or equal to the upper limit of condition (10), the spherical aberration tends to be insufficient, disrupting the balance with the astigmatism and making it difficult to achieve the desired performance.

[0053] Also, the imaging lens 100 of each embodiment satisfies condition (11) when the focal length of the third lens L3 is f3 and the focal length of the fourth lens L4 is f4. 0.7 < |f3 / f4| < 1.3 ···(11)

[0054] Condition (11) is a conditional expression regarding the lens power of the third lens L3 and the lens power of the fourth lens L4.

[0055] When f3 / f4 is less than or equal to the lower limit of condition (11), the astigmatism tends to be excessive, and the distortion also tends to increase, making it difficult to achieve the desired performance. Also, when f3 / f4 is greater than or equal to the upper limit of condition (11), the overall focal length increases and the angle of view tends to become a narrow angle. Although the astigmatism and distortion tend to be improved, the spherical aberration tends to increase, making it difficult to achieve the desired performance. Therefore, by satisfying condition (11), the imaging lens 100 can achieve a balance between shortening (low-profile) and high performance.

[0056] Also, in the imaging lenses 100 of Embodiments 1 to 5, the second lens L2 has a negative power and satisfies condition (16) when the focal length of the second lens L2 is f2 and the focal length of the entire optical system is f. -0.2 < f / f2 < -0.0 ···(16)

[0057] Condition (16) is a conditional expression regarding the focal length of the second lens L2 and the focal length of the entire optical system.

[0058] When it is below the lower limit of the f / f2 condition (16), the lens of f2 with respect to f becomes strong, and spherical aberration and distortion aberration tend to be insufficiently corrected, making it difficult to achieve high performance. Therefore, the imaging lens 100 can achieve high performance by satisfying the condition (16).

[0059] Also, in the imaging lens 100 of Embodiments 6 to 10, the second lens L2 has positive power, and when the focal length of the second lens L2 is f2 and the focal length of the entire optical system is f, it satisfies the condition (16). 0.0 < f / f2 < 0.25 ··· (17)

[0060] Condition (17) is a conditional expression regarding the focal length of the second lens L2 and the focal length of the entire optical system.

[0061] When it is above the upper limit of the f / f2 condition (17), the lens of f2 with respect to f becomes strong, and spherical aberration and distortion aberration tend to be insufficiently corrected, making it difficult to achieve high performance. Therefore, the imaging lens 100 can achieve high performance by satisfying the condition (17).

[0062] 〔Imaging Device〕 Next, an embodiment of an information processing apparatus (PC) including an imaging device using the imaging lens 100 of each embodiment as an imaging optical system will be described.

[0063] FIG. 21 is a diagram showing a schematic configuration of an information processing apparatus including an imaging device having the imaging lens 100 of each embodiment. FIG. 22 is a diagram showing a schematic configuration of the imaging device of FIG. 21. FIG. 23 is a block diagram showing a functional configuration of an information processing apparatus including an imaging device having the imaging lens of each embodiment.

[0064] The information processing apparatus 30 shown in FIGS. 21 to 23 includes at least an imaging device 31, a signal processing unit 32, an image processing unit 33, a control unit 34, a display unit 35, a storage unit 36, a communication unit 37, an input unit 38, and an audio input / output unit 39.

[0065] The imaging device 31 generates an imaging signal by imaging a predetermined visual field area under the control of the control unit 34, and outputs this imaging signal to the signal processing unit 32. As shown in FIG. 22, the imaging device 31 includes at least a cover 311, the imaging lens 100 of each embodiment, and the individual imaging element 312. The imaging device 31 is disposed on the front side of the information processing device 30. Specifically, the imaging device 31 is disposed at a position where it can image the user of the information processing device 30. Of course, the imaging device 31 can appropriately change the disposition position according to the shape, size, and usage mode of the information processing device 30.

[0066] The cover 311 is constituted by using a cover glass or the like which is a member for preventing dirt and dust on the imaging lens 100. Note that the information processing device 30 may further be provided with a lid or the like that opens and closes according to a user operation with respect to the cover 311.

[0067] The individual imaging element 312 receives the image of the imaging object imaged by the imaging lens 100, and generates an imaging signal by performing photoelectric conversion. The individual imaging element 312 is constituted by using a CCD sensor, a CMOS sensor, or the like. Preferably, the individual imaging element 312 has an effective pixel of 8 million pixels or more, that is, a so-called 4K or more (3840×2160 or more), and is arranged in a two-dimensional matrix.

[0068] The signal processing unit 32 performs A / D conversion processing or the like on the imaging signal input from the individual imaging element 312 under the control of the control unit 34, converts it into a digital imaging signal, and outputs it to the image processing unit 33. The signal processing unit 32 is constituted by using, for example, a DSP (Digital Signal Processor) or the like.

[0069] The image processing unit 33 performs predetermined image processing on the digital imaging signal input from the signal processing unit 32 under the control of the control unit 34, and outputs the processed signal to the display unit 35 or the storage unit 36. The image processing unit 33 is configured using, for example, a GPU (Graphics Processing Unit) or the like. Here, the predetermined image processing includes electrical correction processing for shading, white balance adjustment processing, trimming processing for the central part of the image, and noise reduction processing, etc.

[0070] The control unit 34 controls each part constituting the information processing apparatus 30. The control unit 34 includes a processor and a memory. The processor is configured using a CPU, an FPGA (Field-Programmable Gate Array), or the like. The memory is configured using a RAM (Random Access Memory), a ROM (Read Only Memory), or the like.

[0071] The display unit 35 displays the video during shooting on which the image processing unit 33 has performed image processing, the captured imaging image, the still image corresponding to the image signal stored in the storage unit 36, and various information regarding the information processing apparatus 30 under the control of the control unit 34.

[0072] The storage unit 36 stores various information regarding the information processing apparatus 30, programs executed by the information processing apparatus 30, and imaging signals (RAW data, JPEG data) captured by the imaging apparatus 31. The storage unit 36 is configured using a flash memory, an SSD (Solid State Drive), an HDD (Hard Disk Drive), a memory card, or the like.

[0073] The communication unit 37 transmits the imaging signal captured by the imaging apparatus 31 to the outside according to a predetermined communication standard via a network and receives various information input from the outside under the control of the control unit 34. The communication unit 37 uses a communication standard compliant with communication standards such as 3GPP (registered trademark), 4G, LTE, 5G, WiMAX, and Wi-Fi (registered trademark) formulated by the IEEE.

[0074] The input unit 38 receives the user's operation input and outputs operation information corresponding to the received operation to the control unit 34. The input unit 38 is configured using, for example, a touch panel, a keyboard, a mouse, or the like.

[0075] The audio input / output unit 39 receives an external sound input under the control of the control unit 34, converts it into an audio signal, and outputs it to the storage unit 36 or the communication unit 37. Also, the audio input / output unit 39 converts the audio signal input from the storage unit 36 or the communication unit 37 under the control of the control unit 34 and outputs it to the outside. The audio input / output unit 39 is configured using a microphone, a speaker, or the like.

[0076] The information processing apparatus 30 configured as described above can communicate with an external device in high definition of 4K via a network using the imaging apparatus 31 having the imaging lens 100 by means of Web communication.

[0077] In the embodiment, a PC is described as an example of the information processing apparatus 30, but the imaging apparatus 31 can be applied to imaging apparatuses such as tablet-type terminals and mobile phones. Of course, the imaging apparatus 31 may be applied to a Web camera or the like that can communicate with a PC or the like by wire or wirelessly.

[0078] According to the embodiment described above, it is possible to realize a wide-angle field of view, bright, high-performance, and small-sized one.

[0079] Also, according to the embodiment, a half field of view of about 50° can be realized with four lenses.

[0080] Also, according to the embodiment, since the imaging lens 100 can realize a wide-angle field of view, a small F-number, high performance, and small size, in the case of video shooting, it is possible to cope with shooting in various environments such as a dark environment and an increase in the shooting speed.

[0081] Moreover, according to the embodiment, since it is possible to realize a wide-angle field of view, bright, high-performance, and small-sized device, it is possible to enhance the matching between the incident angle in the light-receiving element of the solid-state imaging device on the image side and the light rays incident on the light-receiving surface.

[0082] Moreover, according to the embodiment, since it is possible to configure a bright, high-performance, and small-sized approximately half field of view of 50° with four lenses, it can be used as a single-focus lens for mobile phones such as smartphones and PCs. Therefore, in the case where video shooting with a high pixel count of 4K or more (3840×2160 or more) is required, sufficient aberration correction can be performed compared with conventional imaging lenses, and the required performance can be satisfied.

[0083] Moreover, according to the embodiment, since it is possible to configure a bright, high-performance, and small-sized half field of view of approximately 50° with four lenses, the overall length of the imaging lens 100 in the optical axis direction can be shortened, and the lens diameter can also be reduced, realizing miniaturization. As a result, the refractive power of the miniaturized lens is reduced, and the influence of manufacturing errors and assembly errors can be reduced. As a result, productivity can be improved and production costs can be suppressed.

[0084] Note that various inventions can be formed by appropriately combining a plurality of components disclosed in the information processing apparatus according to the embodiment of the present disclosure. For example, some components may be deleted from all the components described in the information processing apparatus according to the embodiment of the present disclosure described above. Furthermore, the components described in the information processing apparatus according to the embodiment of the present disclosure described above may be appropriately combined.

[0085] Moreover, in the information processing apparatus according to the embodiment of the present disclosure, the above-described "section" can be read as "means", "circuit", or the like. For example, the control section can be read as a control means or a control circuit.

[0086] In addition, the program to be executed by the information processing apparatus according to the embodiment of the present disclosure is provided by being recorded on a computer-readable recording medium such as a CD-ROM, a flexible disk (FD), a CD-R, a DVD (Digital Versatile Disk), a USB medium, or a flash memory in the form of file data that can be installed or executed.

[0087] Alternatively, the program to be executed by the information processing apparatus according to the embodiment of the present disclosure may be configured to be stored on a computer connected to a network such as the Internet and provided by being downloaded via the network.

Example

[0088] Examples 1 to 10 of the imaging lens 100 corresponding to each of Embodiments 1 to 10 are shown below. The meanings of the symbols in each example are as follows. f: Focal length of the entire lens system fl: Focal length of each lens FNo.: Aperture number (F-number) R: Curvature radius of the surface D: Interval between surfaces Nd: Refractive index for the d-line Vd: Abbe number for the d-line SD: Effective radius When the aspherical surface has a depth in the optical axis direction of X, a height from the optical axis of H, a paraxial curvature radius of R, a conic constant of k, and higher-order aspherical coefficients of CN (N is an even number of 4 or more), the aspherical surface is represented by the well-known following formula (15) using the aspherical coefficients. X = (H 2 / R) / [1 + {1 - k(H / r) 2} 1 / 2 + Σ N=4:even CNH N ···(15) Here, Σ N≧4:even means the sum for N being an even number of 4 or more.

[0089] [Example 1] f = 2.1 mm, FNo. = 2.2, HFOV = 45° The data of Example 1 are shown in Table 1.

[0090]

Table 1

[0091] The data of the aspherical surface are shown below.

Table 2

[0092] The values of the parameters for each condition are as follows. Table 3 also describes EP: the incident pupil position.

Table 3

[0093] In this table, in addition to the conditional expressions (1) to (11), (16), (12) to (14) are also described for reference.

Table 4

[0094] Also, in each example, aspherical surfaces are used for the first lens L1 to the fourth lens L4, and the aberrations are well corrected by the aspherical surfaces.

[0095] The aberration diagrams, MTF, and distortion grids for the above Example 1 are shown in FIGS. 2A to 2C. As is clear from each figure, the performance is good.

[0096] [Example 2] f = 1.9 mm, FNo. = 2.0, HFOV = 47° The data of Example 2 are shown in Table 5.

[0097]

Table 5

[0098] The data of the aspherical surface is shown below. [Table 6]

[0099] The values of the parameters for each condition are as follows. [Table 7] [Table 8]

[0100] These aberration diagrams, MTFs, and distortion grids are shown in FIGS. 4A to 4C. As is clear from each figure, the performance is good.

[0101] [Example 3] f = 1.8 mm, FNo. = 2.2, HFOV = 51° The data of Example 3 is shown in Table 9.

[0102] [Table 9]

[0103] The data of the aspherical surface is shown below. [Table 10]

[0104] The values of the parameters for each condition are as follows. [Table 11]

[0105] [Table 12]

[0106] These aberration diagrams, MTF, and distortion grids are shown in FIGS. 6A to 6C. As is clear from each figure, the performance is good.

[0107] [Example 4] f = 1.9 mm, FNo. = 2.0, HFOV = 48° The data of Example 4 are shown in Table 13.

Table 13

[0108] The data of the aspherical surface are shown below.

Table 14

[0109] The values of the parameters for each condition are as follows.

Table 15

[0110]

Table 16

[0111] These aberration diagrams, MTF, and distortion grids are shown in FIGS. 8A to 8C. As is clear from each aberration diagram, the performance is good.

[0112] [Example 5] f = 1.9 mm, FNo. = 2.0, HFOV = 48° The data of Example 4 are shown in Table 17.

Table 17

[0113] The data of the aspherical surface are shown below.

Table 18

[0114] The values of the parameters for each condition are as follows. [Table 19]

[0115] [Table 20]

[0116] These aberration diagrams, MTF, and distortion grids are shown in FIGS. 10A to 10C. As is clear from each aberration diagram, the performance is good.

[0117] [Example 6] f = 2.0 mm, FNo. = 2.2, HFOV = 48° The data of Example 6 are shown in Table 21. [Table 21]

[0118] The data of the aspherical surface are shown below. [Table 22]

[0119] The values of the parameters for each condition are as follows. [Table 23]

[0120] [Table 24]

[0121] These aberration diagrams, MTF, and distortion grids are shown in FIGS. 12A to 12C. As is clear from each aberration diagram, the performance is good.

[0122] [Example 7] f = 2.0 mm, FNo. = 2.2, HFOV = 48° The data of Example 7 are shown in Table 25.

Table 25

[0123] The aspherical data are shown below.

Table 26

[0124] The values of the parameters for each condition are as follows.

Table 27

[0125]

Table 28

[0126] These aberration diagrams, MTF, and distortion grids are shown in Figs. 14A to 14C. As is clear from each aberration diagram, the performance is good.

[0127] [Example 8] f = 2.1 mm, FNo. = 2.2, HFOV = 47° The data of Example 8 are shown in Table 29.

Table 29

[0128] The aspherical data are shown below.

Table 30

[0129] The values of the parameters for each condition are as follows.

Table 31

[0130]

Table 32

[0131] These aberration diagrams, MTFs, and distortion grids are shown in FIGS. 16A to 16C. As is clear from each aberration diagram, the performance is good.

[0132] [Example 9] f = 2.1 mm, FNo. = 2.2, HFOV = 46.5° The data of Example 9 are shown in Table 33.

Table 33

[0133] The data of the aspherical surface are shown below.

Table 34

[0134] The values of the parameters for each condition are as follows.

Table 35

[0135]

Table 36

[0136] These aberration diagrams, MTFs, and distortion grids are shown in FIGS. 18A to 18C. As is clear from each aberration diagram, the performance is good.

[0137] [Example 10] f = 2.1 mm, FNo. = 2.2, HFOV = 46.5° The data of Example 10 are shown in Table 37.

Table 37

[0138] The data of the aspherical surface is shown below.

Table 38

[0139] The values of the parameters for each condition are as follows.

Table 39

[0140]

Table 40

[0141] These aberration diagrams, MTF, and distortion grids are shown in FIGS. 20A to 20C. As is clear from each aberration diagram, the performance is good.

[0142] As described above, in Examples 1 to 10 and FIGS. 2A to 2C, FIGS. 4A to 4C, FIGS. 6A to 6C, FIGS. 8A to 8C, FIGS. 10A to 10C, FIGS. 12A to 12C, FIGS. 14A to 14C, FIGS. 16A to 16C, FIGS. 18A to 18C, and FIGS. 20A to 20C, the imaging lens 100 of the present disclosure is bright, high-performance, and miniaturized (shortened in the optical axis direction), and the semi-field angle is realized with a four-lens configuration of about 50°. It is also clear that it is suitable as an imaging device, particularly an imaging device for a laptop PC.

[0143] As described above, some of the embodiments of the present application have been described in detail with reference to the drawings. However, these are examples, and the present invention can be implemented in other forms with various modifications and improvements based on the knowledge of those skilled in the art, starting from the aspects described in the disclosure column of the present invention.

[0144] 30 Information processing apparatus 31 Imaging device 100 Imaging lens L1 First lens L2 Second lens L3 Third lens L4 Fourth lens S Aperture stop CG Cover glass

Claims

1. A first lens to a fourth lens arranged in order from the object side, and an aperture stop on the object side most distant from the image plane, wherein: The first lens is a positive meniscus lens with a convex surface facing the object side, The second lens has at least one inflection point on at least one surface and is a lens with a small eccentricity ratio, The third lens is a positive lens with a convex surface facing the image plane side and having an inflection point in the peripheral portion of the lens, The fourth lens is a negative lens with a concave surface facing the image plane side and having an inflection point in the peripheral portion, When the focal length of the first lens is f1, the focal length of the fourth lens is f4, and the focal length of the entire optical system is f, the conditions (1), (2) 0.45 < |f / f1| < 0.80... (1) 0.25 < |f4 / f1| < 0.50... (2) An imaging lens that satisfies the above conditions.

2. The imaging lens according to claim 1, wherein when the refractive index of the material of the first lens with respect to the d-line is N1 and the refractive index of the material of the fourth lens with respect to the d-line is N4, the condition (3) N1 < N4... (3) An imaging lens that satisfies the above conditions.

3. The imaging lens according to claim 1, wherein when the refractive index of the material of the first lens with respect to the d-line is N1, the condition (4) 1.49 < N1 < 1.55... (4) An imaging lens that satisfies the above conditions.

4. The imaging lens according to claim 1, wherein when the refractive index of the material of the fourth lens with respect to the d-line is N4, the condition (5) 1.63 < N4 < 1.67... (5) An imaging lens that satisfies the above conditions.

5. The imaging lens according to claim 1, wherein when the focal length of the entire optical system is f and the overall length of the optical system is OAL, the condition (6) 0.60 < f / OAL < 0.75... (6) An imaging lens that satisfies the above conditions.

6. The imaging lens according to claim 1, wherein when the overall length of the optical system is OAL and the effective diameter of the lens on the object side most distant from the image plane is EfD1, the condition (7) 2.9 < OAL / EfD1 < 3.6... (7) An imaging lens that satisfies the above conditions.

7. The imaging lens according to claim 1, wherein when the exit pupil position is EXP and the image height is IH, the condition (9) -0.94 < EXP / IH < -0.70... (8) An imaging lens that satisfies the above conditions.

8. The imaging lens according to claim 1, wherein when the focal length of the first lens is f1 and the focal length of the second lens is f2, the condition (9) 0.01 < |f1 / f2| < 0.40...(9) An imaging lens that satisfies the above condition. **Claim 9** The imaging lens according to claim 1, when the focal length of the first lens is f1 and the focal length of the third lens is f3, the condition (10) 0.25 < f3 / f1 < 0.55...(10) An imaging lens that satisfies the above condition. **Claim 10** The imaging lens according to claim 1, when the focal length of the third lens is f3 and the focal length of the fourth lens is f4, the condition (11) 0.7 < |f3 / f4| < 1.3...(11) An imaging lens that satisfies the above condition. **Claim 11** The imaging lens according to claim 1, the second lens, has a negative power, and when the focal length of the second lens is f2 and the focal length of the entire optical system is f, the condition (16) -0.2 < f / f2 < -0.0...(16) An imaging lens that satisfies the above condition. **Claim 12** The imaging lens according to claim 1, the second lens, has a positive power, and when the focal length of the second lens is f2 and the focal length of the entire optical system is f, the condition (17) 0.0 < f / f2 < 0.25...(17) An imaging lens that satisfies the above condition. **Claim 13** The imaging lens according to claim 1, and an individual image sensor that receives the image formed by the imaging lens and generates an imaging signal, An imaging device comprising: an imaging device. **Claim 14** The imaging device according to claim 13, and a display unit that displays an image corresponding to the imaging signal generated by the imaging device, An information processing device comprising: an information processing device.

Images