Image capturing lens, recognition 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 a recognition 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 to the image side, and an aperture stop S located on the most object side. The first lens L1 is a positive lens having a convex surface on the object side. The second lens L2 is a negative lens having an inflection point on at least one surface and a small thickness deviation ratio. 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 on the object side. 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, a recognition device, and an information processing device.

Background Art

[0002] In recent years, in society, the demand for information security has been increasing in order to prevent data from flowing out of information terminals. As a countermeasure for users, in order to prevent the outflow of information from information terminals or to limit the use of information terminals, passwords are made more complex. However, in conventional information security countermeasures, since it becomes difficult for users to use passwords when they are made more complex, security enhancement using devices such as fingerprint recognition or face authentication using near-infrared rays has also been progressing simultaneously.

[0003] Furthermore, in order to establish higher recognition such as motion sensing, the pixel count of those near-infrared devices has also been increasing.

[0004] In addition, in recent years, laptops have come to be equipped with recognition devices based on the user's face. For this reason, the recognition device is also being miniaturized in consideration of portability. The recognition device required in the market mainly combines functions such as face authentication at the time of login and motion sensing, and a technique is known in which not only the lens of the infrared camera has higher performance but also the number of lenses is reduced (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] Incidentally, in recent years, as infrared cameras, there have emerged those capable of imaging near-infrared bands with peak wavelengths of 850 nm or 940 nm, and those capable of imaging not only near-infrared bands but also monochrome (visible light) wavelength characteristics of 450 nm. For this reason, there has been a demand for an imaging lens that satisfies the optical performance in the visible light wavelength band as well as in the near-infrared band, is smaller in size than conventional imaging lenses for infrared rays, has a wide-angle field of view, is bright, and has high performance.

[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 field 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 a diaphragm disposed on the most object side, wherein the first lens is a positive lens having a convex surface facing the object side, the second lens is a negative lens having at least one inflection point on at least one surface and a small decentration ratio, the third lens is a positive lens having a convex surface facing the image plane side and an inflection point at the lens peripheral portion on the object side surface, the fourth lens is a negative lens having a concave surface facing the image plane side and 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) 0.50 < |f / f1| < 1.40 ···(1) 0.40 < |f4 / f1| < 2.0 ···(2) are satisfied.

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

[0010] Further, the information processing apparatus according to the third aspect of the present disclosure includes the 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 field of view, high brightness, high performance, and small size can be provided.

Brief Description of the Drawings

[0012]

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Embodiments for Carrying Out the Invention

[0013] Hereinafter, an imaging lens, a recognition apparatus, and an information processing apparatus according to the present disclosure will be described with reference to the drawings. Note that the present disclosure is not limited to the following embodiments. Also, each drawing 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 description thereof is omitted.

[0014] [Embodiment] FIGS. 1, 3, 5, 7, 9, and 11 are cross-sectional views showing lens configurations of the imaging lenses according to Embodiments 1 to 6, 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 that are arranged in order from the object side to the image side. Further, the imaging lens 100 includes a diaphragm S (STOP) that is arranged on the object side of the first lens L1.

[0016] In FIGS. 1, 3, 5, 7, 9, and 11, 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 the respective lenses or diaphragms. 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, and 11, the reference numeral CG represents an infrared 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 infrared 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 configured such that, in order from the object side, the aperture stop, the first lens L1, the second lens L2, the third lens L3, and the fourth lens L4 are arranged. The imaging lens 100 is composed of a positive lens for the first lens L1, a negative lens having a negative power for the second lens L2, a positive lens for the third lens L3, and a negative lens for the fourth lens, and has a lens configuration in which positive and negative lenses are arranged in order. In the case of this configuration, it is possible to easily correct spherical aberration and coma aberration, and good telecentricity can also be realized on the image side.

[0018] The first lens L1 is a positive lens with a convex surface facing the object side, and it can be a meniscus lens or a biconvex lens. As in the embodiments described later, there is no problem whether the material of the first lens L1 is plastic or glass.

[0019] The second lens L2 is configured using a negative lens having at least one inflection point on one side and a small decentration ratio, but it can also have inflection points on both sides. Here, having an inflection point on one side means a region including a position from 60% to 80% from the optical axis toward the outer edge with respect to the aperture diameter of the second lens L2 on the surface 4 side or the surface 5 side.

[0020] The third lens L3 is configured using a positive lens with a convex surface facing the image side and having an inflection point at the lens peripheral portion on the object side surface. Here, having an inflection point at the lens peripheral portion means a region including a position from 80% to 90% from the optical axis toward the outer edge with respect to the aperture diameter of the third lens L3 on the surface 7 side.

[0021] The fourth lens L4 is configured using a negative lens with a concave surface facing the image side and having an inflection point at the peripheral portion. Here, having an inflection point at the peripheral portion means a region including a position from 60% to 80% from the optical axis toward the outer edge with respect to the aperture diameter of the fourth lens L4 on the surface 8 side.

[0022] The first lens L1 to the fourth lens L4 configured as described above may be an aspherical lens or a spherical lens, but the second lens L2, the third lens L3, and the fourth lens L4 are all aspherical lenses, each having a characteristic aspherical shape. Further, by forming the second lens L2, the third lens L3, and the fourth lens L4 into a shape having 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 material of the lens, as shown in the embodiments, an optical plastic material or a glass material is used.

[0024] Figures 2A to 2C, Figures 4A to 4C, Figures 6A to 6C, Figures 8A to 8C, Figures 10A to 10C, and Figures 12A to 12C are, respectively, the longitudinal aberration diagrams, MTFs, and distortion grids of the imaging lens 100 of Embodiments 1 to 6. 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), C-line (red: 653.3 nm), and near-infrared I940 (940 nm) are shown. 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 only for 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). 0.50 < |f / f1| < 1.40 ···(1) 0.40 < |f4 / f1| < 2.0 ···(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 be short, which is advantageous for achieving a wider angle of view. However, the aberration tends to be excessive and the distortion aberration also tends to increase, making it difficult to achieve the desired performance. Also, when f / f1 is equal to or greater than the upper limit of condition (1), the spherical aberration and the aberration tend to be improved, but the angle of view tends to be narrow, so the desired performance of the present invention cannot be achieved, which is not desirable. Therefore, by satisfying condition (1), the imaging lens 100 can achieve a balance between shortening (lower 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), the aberration tends to be excessive and the spherical aberration also occurs significantly, 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 aberration and making it difficult to achieve the desired performance.

[0030] That is, when the imaging lens 100 satisfies conditions (1) and (2), a balance between spherical aberration and astigmatism can be achieved, and a bright, high-performance, and small (compact) imaging lens 100 can be realized. 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, 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, the imaging lens 100 of each embodiment satisfies condition (3). 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, and the fourth lens L4 is a negative lens. In the embodiments of the present 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, when the refractive index of the material of the first lens L1 with respect to the d-line is N1, the imaging lens 100 of each embodiment 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 the cost increases, which is not preferable. Also, when the refractive index N1 is above the upper limit of condition (4), the optical performance is affected by chromatic aberration, which is not preferable. Therefore, when the imaging lens 100 satisfies 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, when the refractive index of the material of the fourth lens L4 with respect to the d-line is N5, the imaging lens 100 of each embodiment 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 compact imaging lens 100 can be realized.

[0038] Also, when the focal length of the entire optical system (imaging lens 100) is f and the overall length in the longitudinal direction of the optical system (imaging lens 100) is OAL, the imaging lens 100 of each embodiment satisfies condition (6). 0.60 < f / OAL < 0.90 ···(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 below 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 above the upper limit of condition (6), the overall length of the optical system is small, but it becomes difficult to widen the 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] Also, 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). 2.2 < OAL / EfD1 < 3.2 ···(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 below 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 above the upper limit of condition (7), the performance of the optical system is improved, but it becomes difficult to achieve miniaturization (shortening in the optical axis direction). By satisfying condition (7), the imaging lens 100 can achieve miniaturization (shortening in the optical axis direction) and high performance.

[0044] In addition, the imaging lens of each embodiment satisfies condition (9) when the exit pupil position is EXP and the image height is IH. -1.3 < EXP / IH < -0.90 ···(8)

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

[0046] When EXP / IH is below the lower limit of condition (8), the incident angle of light rays tends to be low, but it tends to be difficult to shorten the overall length of the optical system for miniaturization. When EXP / IH is above 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 achieve miniaturization.

[0047] In addition, the imaging lens of each embodiment satisfies condition (9) when the focal length of the first lens L1 is f1 and the focal length of the second lens L2 is f2. 0.40 < |f1 / f2| < 0.71 ···(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 equal to or less than the lower limit of condition (9), since the lens power of f2 with respect to f1 becomes weak, spherical aberration and distortion aberration tend to be insufficient for aberration correction, making it difficult to achieve high performance. Also, when |f1 / f2| is equal to or greater than the upper limit of condition (9), astigmatism tends to increase, which is not desirable. Therefore, the imaging lens 100 can achieve high performance by satisfying condition (9).

[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, condition (10) is satisfied. 0.3 < f3 / f1 < 2.8 ···(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 equal to or less than the lower limit of condition (10), astigmatism has an over tendency, and distortion aberration and coma aberration also occur significantly, making it difficult to realize the desired performance. Also, when f3 / f1 is equal to or greater than the upper limit of condition (10), spherical aberration has an under tendency, disrupting the balance with astigmatism and making it difficult to realize the desired performance.

[0053] Also, for the imaging lens 100 of each embodiment, when the focal length of the third lens L3 is f3 and the focal length of the fourth lens L4 is f4, condition (11) is satisfied. 0.5 < |f3 / f4| < 2.0···(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 equal to or less than 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 equal to or greater than the upper limit of condition (11), the overall focal length increases and the angle of view tends to become a clamping angle. Thus, 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] In addition, each of the imaging lenses 100 of the embodiments has a near-infrared region corresponding coating (laminated coating) corresponding to near-infrared rays, in which each of the first lens L1 to the fourth lens L4 is coated on the lens surface. This near-infrared region corresponding coating transmits light in the band of 450 to 940 nm and has a reflectance of 2% or less at least in the near-infrared region band of 850 to 940 nm.

[0057] FIG. 13 shows the reflectance characteristics of an example of the near-infrared region corresponding coating applied to at least one surface of each of the lens surfaces of the first lens L1 to the fourth lens L4 of the imaging lens 100 according to Embodiments 1 to 6. In FIG. 13, the horizontal axis represents the wavelength band and the vertical axis represents the reflectance. In FIG. 13, curve K1 shows the reflectance characteristics of a general multi-coating, and curve K2 shows the reflectance characteristics of the near-infrared region corresponding coating (near-infrared region corresponding multi-coating).

[0058] On the surface of each of the first lens L1 to the fourth lens L4 of the imaging lens 100, a near-infrared region corresponding coat (solid line) having the reflectance characteristics shown by the curve K1 in FIG. 13 is coated (coated or laminated) on the lens. By coating such a near-infrared region corresponding coat on the lens (coating or laminating), it becomes possible to realize an imaging lens corresponding to near-infrared rays and an imaging device including this imaging lens. Note that the near-infrared region corresponding coat on the surface of each of the first lens L1 to the fourth lens L4 is coated by being adhered and formed by a well-known technique. Of course, a sheet of the near-infrared region corresponding coat may be attached to the surface of each of the first lens L1 to the fourth lens L4.

[0059] The imaging lens 100 of the embodiment of the present disclosure is composed of four lenses, and has eight lens surfaces. The transmittance of the imaging lens 100 is also an important element as an imaging device and a recognition device.

[0060] Here, when simply calculating the transmittance of the four-lens configuration imaging lens 100 in Embodiments 1 to 6 of the present disclosure at a near-infrared ray of 940 nm, in the case of the four-lens configuration, since there are eight reflecting surfaces, it becomes the eighth power of (1 - reflectance). Therefore, when a general multi-coat (dotted line) shown by the curve K1 in FIG. 13 is coated, the transmittance at 940 nm is 4.1% when the reflectance at 940 nm is 33%, which is not preferable.

[0061] On the other hand, as shown by the curve K2 in FIG. 13, when similarly calculating the transmittance at 940 nm of the near-infrared region corresponding multi-coat (curve K2), when the reflectance at 940 nm is 2% (refer to the straight line H1), the transmittance at 940 nm = (1 - 0.02)^8 = 85.1%, and a good transmittance can be realized, which is suitable as the imaging lens 100 of an imaging device capable of near-infrared imaging.

[0062] Therefore, in each of the imaging lenses 100 of Embodiments 1 to 6, a near-infrared region corresponding multi-coat for near-infrared correspondence is coated on the surface of each of the first lens L1 to the fourth lens L4, transmits light in the band of 450 to 940 nm, and has a reflectance of 2% or less at least in the band of the near-infrared region of 850 nm to 940 nm. As shown by the curve K2 in FIG. 13, in the near-infrared region corresponding multi-coat, the reflectance is also low in the visible light region band of 450 to 650 nm. However, considering the sensor characteristics (image sensor characteristics) of the near-infrared imaging device, the reflectance in the visible light region may be 2% or more.

[0063] Also, regarding the cover glass described in each of Embodiments 1 to 6, an infrared corresponding multi-coat with a reflectance of 2% or less in the band of nearly 850 to 940 nm as shown in FIG. 13 is coated, corresponding to the near-infrared imaging device.

[0064] 〔Imaging device〕 Next, an embodiment of an information processing device (PC) including a recognition device using the imaging lens 100 of each embodiment as an imaging optical system will be described.

[0065] FIG. 14 is a diagram showing a schematic configuration of an information processing device including a recognition device having the imaging lens 100 of each embodiment. FIG. 15 is a diagram showing a schematic configuration of the recognition device of FIG. 14. FIG. 16 is a block diagram showing a functional configuration of an information processing device including a recognition device having the imaging lens of each embodiment.

[0066] The information processing device 30 shown in FIGS. 14 to 16 includes at least a recognition 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, an audio input / output unit 39, and an imaging device 40.

[0067] The recognition 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. 15, the recognition device 31 includes at least a cover 311, the imaging lens 100 of each embodiment, and the individual imaging element 312. The recognition device 31 is disposed on the front side of the information processing device 30. Specifically, the recognition device 31 is disposed at a position parallel to the imaging device 40.

[0068] The cover 311 is configured using a cover glass or the like which is a member for preventing dirt and dust on the imaging lens 100.

[0069] 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 configured using a CCD sensor, a CMOS sensor, or the like. The individual imaging element 312 preferably has an effective pixel of 300,000 pixels or more, that is, a so-called VGA or higher (640×480 or higher), arranged in a two-dimensional matrix.

[0070] 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 configured using, for example, a DSP (Digital Signal Processor) or the like. Further, the signal processing unit 32 performs A / D conversion processing or the like on the imaging signal input from the imaging device 40 under the control of the control unit 34, converts it into a digital imaging signal, and outputs it to the image processing unit 33.

[0071] 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 it 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.

[0072] 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.

[0073] The display unit 35 displays, under the control of the control unit 34, a video during shooting in which the image processing unit 33 has performed image processing, a captured image, a still image corresponding to an image signal stored in the storage unit 36, and various types of information regarding the information processing apparatus 30.

[0074] The storage unit 36 stores various types of information regarding the information processing apparatus 30, programs executed by the information processing apparatus 30, and imaging signals (RAW data, JPEG data, etc.) captured by the imaging apparatus 40. 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.

[0075] The communication unit 37, under the control of the control unit 34, transmits, via a network, an imaging signal captured by the imaging apparatus 40 to the outside in accordance with a predetermined communication standard, and receives various types of information input from the outside. 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) established by the IEEE.

[0076] The input unit 38 receives a 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.

[0077] The audio input / output unit 39 receives the input of external sound, converts it into an audio signal under the control of the control unit 34, and outputs the audio signal to the storage unit 36 or the communication unit 37. Further, 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, and the like.

[0078] The imaging device 40 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. The imaging device 40 is disposed on the front side of the information processing device 30. Specifically, the imaging device 40 is disposed at a position where it can image the user of the information processing device 30. Of course, the arrangement position of the imaging device 40 can be appropriately changed according to the shape, size, and usage mode of the information processing device 30.

[0079] The information processing device 30 configured as described above can perform face recognition and the like with a high image quality of 300,000 pixels or more with an external device using the recognition device 31 having the imaging lens 100, and can also perform communication by Web communication via a network.

[0080] In the embodiment, a PC is described as an example of the information processing device 30, but the recognition device 31 can be applied to imaging devices such as tablet terminals and mobile phones. Of course, the recognition device 31 may be applied to a Web camera or the like that can communicate with a PC or the like by wire or wirelessly.

[0081] According to the embodiment described above, it is possible to realize a device with a wide-angle field of view, bright, high performance, and small size.

[0082] Further, according to the embodiment, a semi-field angle of about 38.5° can be realized with four lenses.

[0083] In addition, according to the embodiment, since the imaging lens 100 can have a wide angle of view, a small F-number, high performance, and a small size, in the case of video shooting, it can cope with shooting in various environments such as a dark environment and an increase in the shooting speed.

[0084] In addition, according to the embodiment, since it is possible to realize a wide angle of view, brightness, high performance, and a small size, 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 beam incident on the light receiving surface.

[0085] In addition, according to the embodiment, since it is possible to configure an approximately half angle of view of 38.5° with four lenses, which is bright, high performance, and small in size, for example, it can be used as a single-focus lens for mobile phones such as smartphones and PCs. Therefore, when high pixel number video shooting of VGA or higher (640×480 or higher) is required, sufficient aberration correction can be performed compared with conventional imaging lenses, and the required performance can be satisfied.

[0086] In addition, according to the embodiment, since it is possible to configure an approximately half angle of view of 38.5° with four lenses, which is bright, high performance, and small in size, 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.

[0087] 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.

[0088] In the information processing apparatus according to the embodiment of the present disclosure, the "section" described above 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.

[0089] The program to be executed by the information processing apparatus according to the embodiment of the present disclosure is provided as file data in a form that can be installed or executed and is 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.

[0090] 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

[0091] Examples 1 to 8 of the imaging lens 100 corresponding to Embodiments 1 to 6 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 with respect to the d-line Vd: Abbe number with respect to the d-line SD: Effective radius For an aspherical surface, when the depth in the optical axis direction is X, the height from the optical axis is H, the paraxial curvature radius is R, the conic constant is k, and the higher-order aspherical coefficient is 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 coefficient. X=(H 2 / R) / [1+{1-k(H / r) 2} 1 / 2 +Σ N=4:even CNHN ···(15) Here, Σ N≧4:even means the sum for even N of 4 or more.

[0092] [Example 1] f = 1.4 mm, FNo. = 2.0, HFOV = 40° The data of Example 1 are shown in Table 1.

[0093]

Table 1

[0094] The data of the aspherical surface are shown below.

Table 2

[0095] The values of the parameters for each condition are as follows. Note that Table 3 also describes EP: the entrance pupil position.

Table 3

[0096] In this table, in addition to the conditional expressions (1) to (11), (12) to (14) are also described for reference.

Table 4

[0097] 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.

[0098] 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.

[0099] [Example 2] f = 1.5 mm, FNo. = 2.0, HFOV = 38.5° The data of Example 2 are shown in Table 5.

[0100]

Table 5

[0101] The aspherical data are shown below.

Table 6

[0102] The values of the parameters for each condition are as follows.

Table 7

Table 8

[0103] These aberration diagrams, MTF, and distortion grids are shown in Figs. 4A to 4C. As is clear from each figure, the performance is good.

[0104] [Example 3] f = 1.5 mm, FNo. = 2.0, HFOV = 38.5° The data of Example 3 are shown in Table 9.

[0105]

Table 9

[0106] The aspherical data are shown below.

Table 10

[0107] The values of the parameters for each condition are as follows.

Table 11

[0108]

Table 12

[0109] These aberration diagrams, MTFs, and distortion grids are shown in FIGS. 6A to 6C. As is clear from each diagram, the performance is good.

[0110] [Example 4] f = 1.5 mm, FNo. = 2.0, HFOV = 38.5° The data of Example 4 are shown in Table 13.

Table 13

[0111] The data of the aspherical surface are shown below.

Table 14

[0112] The values of the parameters for each condition are as follows.

Table 15

[0113]

Table 16

[0114] These aberration diagrams, MTFs, and distortion grids are shown in FIGS. 8A to 8C. As is clear from each aberration diagram, the performance is good.

[0115] [Example 5] f = 1.4 mm, FNo. = 2.0, HFOV = 38.5° The data of Example 5 are shown in Table 17.

Table 17

[0116] The data of the aspherical surface is shown below.

Table 18

[0117] The values of the parameters for each condition are as follows.

Table 19

[0118]

Table 20

[0119] 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.

[0120] [Example 6] f = 1.9 mm, FNo. = 2.0, HFOV = 32.4° The data of Example 6 are shown in Table 21.

Table 21

[0121] The data of the aspherical surface is shown below.

Table 22

[0122] The values of the parameters for each condition are as follows.

Table 23

[0123]

Table 24

[0124] 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.

[0125] As described above with reference to Examples 1 to 6 and FIGS. 2A to 2C, FIGS. 4A to 4C, FIGS. 6A to 6C, FIGS. 8A to 8C, FIGS. 10A to 10C, and FIGS. 12A to 12C, the imaging lens 100 of the present disclosure is bright, high-performance, and miniaturized (shortened in the optical axis direction), and realizes a half field angle of about 50° with a five-lens configuration. It is also clear that it is suitable as an imaging device, particularly an imaging device for a laptop PC.

[0126] 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, including the aspects described in the disclosure column of the present invention.

[0127] 30 Information processing device 31 Recognition 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, An aperture stop arranged on the most object side, Comprising, The first lens is A positive lens with a convex surface facing the object side, The second lens is A negative lens having an inflection point on at least one side and a small eccentricity ratio, The third lens is A positive lens with a convex surface facing the image plane side and an inflection point at the lens peripheral part on the object side surface, The fourth lens is A negative lens with a concave surface on the image plane side and an inflection point at the peripheral part, 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), (2) 0.50 < |f / f1| < 1.40... (1) 0.40 < |f4 / f1| < 2.0... (2) An imaging lens that satisfies.

2. The imaging lens according to claim 1, Each of the first lens to the fourth lens is Coated on the lens surface, and at least one surface has a near-infrared region corresponding coat corresponding to near-infrared rays, The near-infrared region corresponding coat is Transmits light in the band of 450 to 940 nm, and has a reflectance of 2% or less in at least the band of 850 nm to 940 nm in the near-infrared region, An imaging lens.

3. The imaging lens according to claim 1, 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, condition (3) N1 < N4... (3) An imaging lens that satisfies.

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

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

6. The imaging lens according to claim 1, When the focal length of the entire optical system is f and the overall length of the optical system is OAL, condition (6) 0.60 < f / OAL < 0.90... (6) An imaging lens that satisfies.

7. The imaging lens according to claim 1, When the overall optical length is OAL and the effective diameter of the lens on the most object side is EfD1, condition (7) 2.2 < OAL / EfD1 < 3.2... (7) An imaging lens that satisfies.

8. The imaging lens according to claim 1, when the exit pupil position is EXP and the image height is IH, the condition (8) -1.3 < EXP / IH < -0.90... (8) An imaging lens that satisfies the above.

9. The imaging lens according to claim 1, when the focal length of the first lens is f1 and the focal length of the second lens is f2, the condition (9) 0.40 < |f1 / f2| < 0.71... (9) An imaging lens that satisfies the above.

10. 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) 0.3 < f3 / f1 < 2.8... (10) An imaging lens that satisfies the above.

11. 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) 0.5 < |f3 / f4| < 2.0... (11) An imaging lens that satisfies the above.

12. The imaging lens according to claim 2, An individual image sensor that receives the image formed by the imaging lens and generates an imaging signal, Comprising: Recognition device.

13. An information processing apparatus comprising the recognition device according to claim 12, Information processing device.

Images